KOKX NWS Online Skywarn Class Scheduled Wednesday 7/22 at 7 pm

NWS Online Skywarn Class Scheduled Wednesday 7/22 at 7pm

Weather.gov > New York, NY > NWS Online Skywarn Class Scheduled Wednesday 7/22 at 7pm

Weather Service’s (NWS) voluntary Skywarn Spotter Team.

Learn all about severe weather. We will teach you to observe and report specific types of clouds that form “before” severe weather (hail, high winds, or even a tornado) develops. The information you provide will be used with our radar data to provide more accurate warning services for your and downstream communities that are in the path of thunderstorms. You will also be given safety tips to prepare for and respond to flash floods, severe thunderstorms, and lightning.

This free 2 ½ hour class is for the general public, including emergency managers, first responders, amateur radio operators, teachers, and students.

Registration URL: https://attendee.gotowebinar.com/register/5120854827844335361
Webinar ID: 112-779-483

You will receive email notification of How to Join the Webinar.

Please also visit our local Skywarn page for additional information on our Skywarn program.

Mark Kramer, Chair

New York City/Long Island AMS Chapter

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Stewartsville June 2015 Summary

Stewartsville Monthly Weather Observation Summary
Jun-15
DAY MAX MIN MEAN PRECIP COMMENTS
1 63.0 54.0 58.5 1.64
2 58.0 49.0 53.5 0.61 Storm total 3.11
3 71.0 52.0 61.5 0.00
4 69.0 54.0 61.5 0.00
5 73.0 55.0 64.0 0.01
6 82.0 57.0 69.5 0.04
7 77.0 48.0 62.5 0.00
8 84.0 62.0 73.0 0.46
9 82.0 64.0 73.0 0.18 shower around 10am. Maybe more?
10 83.0 57.0 70.0 0.00
11 89.0 66.0 77.5 0.02
12 92.0 67.0 79.5 0.00
13 84.0 70.0 77.0 0.00
14 88.0 62.0 75.0 0.80
15 87.0 69.0 78.0 0.23
16 85.0 65.0 75.0 0.30
17 82.0 60.0 71.0 0.00
18 69.0 63.0 66.0 0.05
19 85.0 67.0 76.0 0.01
20 70.0 63.0 66.5 0.31
21 88.0 69.0 78.5 0.34
22 89.0 67.0 78.0 0.00
23 87.0 68.0 77.5 0.00
24 83.0 62.0 72.5 0
25 80.0 56.0 68.0 0.01
26 82.0 63.0 72.5 0.04
27 69.0 57.0 63.0 1.07
28 73.0 58.0 65.5 0.66
29 78.0 57.0 67.5 0.00
30 84.0 60.0 72.0 0.00
6.78
Extreme High 92.0 Date: 6/12/2015
Extreme Low 48.0 Date: 6/7/2015
Mean Max: 79.5
Mean Low: 60.7
Mean: 70.1
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JUNE 2015 CLIMATOLOGICAL SUMMARY REISTERSTOWN CITY MARYLAND by Observer in charge/NJWO member Ray Muller

JUNE 2015 CLIMATOLOGICAL SUMMARY
REISTERSTOWN CITY MARYLAND
by Observer in charge/NJWO member Ray Muller

Average maximum temperature 82.0°
Average minimum temperature 65.5°
Average mean temperature 73.8°
High temperature 93° (23/1549)
Low temperature 54° (3/0654)
Max daily range in temperature 26° 92°-66° (11)
Min daily range in temperature 8° 62°-54° (3)
Number of 90° or more days 6
Min max temperature 62° (3)
Max min temperature 73° (23)
Heating degree days 13
Cooling degree days 300

Monthly precipitation 12.10″
Year-to-date precipitation (through 6/30) 26.63″
Max precipitation in 6 hours 0.86″ (1)
Max precipitation in 12 hours 1.21″ (1)
Max precipitation in 1 calendar day 2.46″ (1)
Number of precipitation days with .01″ or more 17
Number of precipitation days wth .10″ or more 11
Number of precipitation days with .50″ or more 9
Number of precipitation days with 1.00″or more 5
Number of precipitation days with 2.00″or more 1

Weather types
Fog 12
Dense Fog 2
Thunder 14
Haze 7
Smoke 2

Sky cover
Clear days 4
Partly cloudy days 14
Cloudy days 12
Mean sky cover (sunrise to sunset) 6.3
Estimated percent of possible sunshine 52

Pressure
Highest barometric pressure 30.24″ (3)
Lowest barometric pressure 29.64″ (28)

Winds
Daily prevailing direction West
Mean speed 11.3 MPH
Fastest mile 29 MPH from 280° (9)
Peak wind gust 42 MPH from the W (9)
Gale wind days 3
Damaging wind days 0

Relative Humidity
Mean relative humidity
0700 89%
1300 64%
1900 67%
Minimum relative humidity 41% (9/1500)
Maximum relative humidity 100% on 9 separate days, mostly AM

Minimum visibility 1/4 mile in dense fog (2)
Number of days with:
stratus clouds 5
fractostratus clouds 16
cumulus clouds 20
stratocumulus clouds 10
altocumulus clouds 14
altostratus clouds 10
cirrus clouds 14
cirrostratus clouds 7
cirrocumulus clouds 6
cumulonimbus clouds 5
mammatus clouds observed during a few special weather observations

Number of days with lightning: cloud-to-cloud (8 observed)
and cloud-to-ground (10 observed)
On the 1st and 9th cloud-to-ground lightning strikes were less than a minute apart at times according to my lightning detector.

Summary: Rainfall was over 8 inches above normal this month. Temperatures were slightly above normal.
Based on short term records back to June 2011, this is the wettest June on record for the Reisterstown Office location.


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June 2015 – Weather Station Highlights – Gaithersburg 2WNW Maryland by Kevin Shaw, Observer and NJWO contributing member

June 2015 was wetter and warmer than normal. It was much more extreme
on the precipitation side. Three daily precipitation records were set,
highlighted by the 3.10″ on the 27th which was the third wettest June
day ever. Coincidentally it remained mostly in the 60s all day, topping out
at 69.6° which rounds to 70°, but still set a daily record low max
temperature record for that date. The lawns and gardens in the community
are now quite green after a drier than normal spring. Other daily
precipitation records were set on the 20th (1.52″ – remnants of Tropical
Storm Bill) and 23rd (1.43″ – mostly from a very intense thunderstorm
with a 26.18”/hr max rain rate at 1809 EDT) which also coincidentally
was the day of the highest temperature for the month (93°) that tied
(with 2010) the daily record high temperature for the date. The minimum
temperature of 72° on the 14th also set a daily high min temperature
record. This reading occurred during our mid-month hot spell, when we
hit 90° a few times, and recorded several 70+ minimum temperatures,
tying record high minimum temperature records on three dates (12, 15, 21).
Both the beginning (especially) and end of the month were generally

cooler than normal. During the month 17 days of measurable rain were
recorded, well above normal. The 9.68″ monthly precipitation total is
now the 3rd largest ever for June.

The average maximum temperature for the month was 81.6° (-1.3°), the
average minimum temperature was 65.0°(+3.9°), the second highest
average minimum in my 37 year POR (period of record), only topped
by the 66.7° recorded in 2010. The resultant mean average temperature
for the month was 73.3° (+1.3°). Both the average max and average mean
temp values were in the middle of the “POR pack” as to the wormest/
coolest ever. The highest temperature recorded during the month was
the record-tying 93° on the 23rd. We had a modest 4 days with max
temperatures at or above 90° (normal is about 5.4), and an above normal
amount of minimum temperatures at or above 70° (10).

The month’s total precipitation amount of 9.68″ was 5.28″ above the
normal June amount of 4.40″. The 17 days of measurable precipitation
during the month was well above the long term average of 11.4 days. This

June ties 2006 for second place all-time in my POR, 1998 had 20 days
of measurable precipitation for the top spot in that category. The year
to date (YTD) precipitation total of 25.10″ now puts us 2.56″ above the

normal YTD average amount for this time of year of 22.54″.

The monthly barometric pressure extremes were a very modest 30.21″
on the 3rd and 4th in the middle of our coolest spell of the month and
a 29.66″ recorded in the early morning hours of the 28th when our
biggest rainstorm of the month was just exiting our area. Average
barometric pressure for the month was 29.96″, not the same value
you would get if you averaged the two extreme values (29.94″)
I had for the month but pretty darn close. So far with four months
study under my belt, this relationship has shown up as the same in
March, 0.06″ difference in April, and 0.02″ in May and June.
It looks promising for developing some sort of relationship there.
Further study needed at least through the rest of the year.

The distribution of 8 sunny, 13 partly cloudy and 9 cloudy days did
not align particularly well with the much above normal precipitation
pattern, nor the number of days with measurable precipitation, but
the great amount of warm, humid days during the middle of the month
did align somewhat.

There was 16 heating degree days and 266 cooling degree days.
There were 6 days with fog (close to long-term averages) and 8
days with thunder (a bit above the long-term average of 6).
The peak wind gust during June was a modest 20 MPH (WSW)
during a strong thunderstorm on the 23rd. I observed the storm
and I believe winds were actually gusting in much more exposed
locations to an estimated 35-40 MPH. The current anemometer
siting is about 23 feet off the ground in the back of the house,
and surrounded by trees and in the middle of our townhouse
cluster so the readings are significantly muted at times.

My maximum temperature frequencies included 4 days at or
above 90°, 16 days at or above 80°, 7 days between 70°and 79°,
and 3 days between 60° and 69°, On the minimum temperature
frequency side of things, there were 5 days between 50°-59°,
15 days between 60°-69°, and 10 days with mins of 70° or
greater.

The diurnal range average was a bit below normal (16.6° vs
the normal 21.8°). The max daily range of 25.5° occurred on
the 11th as we headed into our mid-month heat wave. The lowest
daily temperature range of 4.2° occurred on the 3rd during our
coolest day of the month with lots of clouds and a bit of light
rain. We had a total of 3 days during the month with a diurnal
range lower than 10° while there were only 7 days with ranges
of 20° or more.

The month of June had a nice cool beginning and ending to the
month, with a warm to hot middle. As has been the case the
past few years, the warm nights persisted and were the reason
for the above normal temperatures. Precipitation was fairly
evenly dispersed during the month, with significantly more the
last half (7.26″) than the first half (2.42″) though the
number of measurable precipitation days was about even
(8 first half, 9 second half). So far in July it appears that
this relatively cool and wet pattern will be carrying over,
at least through the first part of the month. The details for July
will be coming next, in a few short weeks. Have a great summer!
I am hoping for a cool, active summer. Let’s see what happens!

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New NWS graphic icons for forecasts starting 7-7-15

2015-07 FOR IMMEDIATE RELEASE: June 29, 2015

Picturing the forecast:
National Weather Service graphics developed with NCAR research

Note: Examples of the graphics can be viewed at these two sites:

· https://www2.ucar.edu/atmosnews/news/16094/picturing-forecast-national-weather-service-graphics-developed-ncar-research

· www.weather.gov (enter a forecast location)

BOULDER – New online graphics being rolled out this summer by the National Weather Service (NWS) are based on research by a team of risk communication experts at the National Center for Atmospheric Research (NCAR) who focused on how to better convey forecast information visually.

Beginning July 7 the NWS will use the redesigned icons for all weather.gov local forecasts. These point-and-click forecasts influence weather-related decisions by people across the country, drawing 2 to 4 million unique web views daily.

The new icons will feature split images and color-coded boxes to better communicate the existence, timing, and potential severity of upcoming weather threats. For example, instead of portraying a night as entirely rainy, a split image could show a 30 percent chance of rain in the early part of the evening, followed by partial clearing after midnight. Colored rectangles drawn around the images will also be used to call attention to weather threats, with yellow denoting a watch, orange denoting an advisory, and red denoting a warning.

The changes are based on several years of work by a multidisciplinary team at NCAR that worked closely with the NWS, an agency within the National Oceanic and Atmospheric Administration. The team developed prototype graphics and surveyed tens of thousands of weather.gov local forecast users, finding that specific improvements to the graphics could greatly improve public understanding of the forecasts.

“We want to help people better understand when there’s a major weather threat and when it’s likely to occur,” said NCAR’s Julie Demuth, a researcher who specializes in communicating weather risks to the public. “The main goal is to better convey information that’s critical for protecting lives and protecting property.”

Eli Jacks, acting chief of the NWS’s Forecast Services Division, said the changes are an important step toward helping people make better use of NWS forecasts.

“Just putting out the forecast is no longer enough,” he said. “This helps users interpret the forecast more easily and use it to make informed decisions.”

NWS director Louis Uccellini said the new project demonstrates the importance of research in communicating forecasts to the public.

“Research provides the essential backbone to any effective operational product used by the National Weather Service to protect lives and property,” Uccellini said. “Not only must we have advancements in atmospheric science to improve forecasts and services, we must also infuse social science to ensure we are communicating forecast information in a way that is clear and understandable so people can take appropriate action.”

The work was primarily funded by the NWS, with additional support from NOAA and the National Science Foundation, which sponsors NCAR.

Forecasts at a glance

Demuth and her colleagues began looking into the issue several years ago when the NWS wanted to determine if the icons could communicate weather information more clearly. An icon depicting rain, for example, might prompt people to cancel outdoor plans even if there was just a 10 percent chance of showers for a few hours.

The research team, working with the NWS, focused on better transmitting two aspects of a forecast that are crucial for helping people understand their risk: the existence of a hazardous weather threat and the timing of that threat. They developed experimental graphics and text with the goal of conveying sometimes complex information in a way that is easy to interpret.

“This is supposed to be a forecast at a glance, so we adapted the approach using NCAR’s work as a basis.” Jacks said. “Ideally a user will look at it and get a pretty good idea of what is expected.”

Demuth and her colleagues conducted two rounds of surveys with more than 13,000 users of NWS forecasts, asking them to evaluate designs to see which one was best at communicating a severe thunderstorm warning and a flood watch.

The surveys showed that users were significantly better at identifying the timing and nature of the weather threat when the information was presented with new graphics and reinforced with wording that stated the start and stop times of the threat. For example, more than 97 percent of survey respondents correctly identified the start and end time of the flood watch with the revamped graphics and text, compared to less than 4 percent in a control group using the existing NWS presentation.

The research team summarized its findings in a 2013 paper in Weather and Forecasting, an American Meteorological Society journal.

Building on this work, the NWS further refined the icons and began to test them last year, asking for input from thousands of users. The agency is now previewing the new graphical approach on its website as it prepares to launch the new version across the nation next month.

“This work illustrates the importance of evaluating how people interpret information about risks, particularly when it’s a matter of public safety,” Demuth said. “Making improvements in how we communicate hazardous weather information—even seemingly small improvements—can translate into very large benefits for society.”

“It’s gratifying to be part of a collaboration where NCAR research is being used to help the National Weather Service alert people across the U.S. about potentially dangerous weather," said Thomas Bogdan, president of the University Corporation for Atmospheric Research. "This is a great example of how investments in science lead to substantial benefits for society.”

The University Corporation for Atmospheric Research manages NCAR under sponsorship by the National Science Foundation.

Any opinions, findings and conclusions, or recommendations expressed in this release do not necessarily reflect the views of the National Science Foundation.

Happy 4th of July!

Mark Kramer, Chair

New York City/Long Island AMS Chapter

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Stewartsville May 2015 Summary

Stewartsville Monthly Weather Observation Summary
May-15
DAY MAX MIN MEAN PRECIP COMMENTS
1 66.0 40.0 53.0 0.00
2 74.0 44.0 59.0 0.00
3 81.0 43.0 62.0 0.00
4 85.0 47.0 66.0 0.00
5 83.0 56.0 69.5 0.00
6 71.0 55.0 63.0 0.00
7 82.0 50.0 66.0 0.00
8 86.0 52.0 69.0 0.00
9 73.0 56.0 64.5 0.00
10 84.0 60.0 72.0 0.00
11 86.0 68.0 77.0 0.00
12 85.0 63.0 74.0 0.00
13 69.0 49.0 59.0 0.00
14 73.0 42.0 57.5 0
15 76.0 44.0 60.0 0.00
16 83.0 54.0 68.5 0.00
17 83.0 62.0 72.5 0.00
18 80.0 55.0 67.5 0.00
19 83.0 55.0 69.0 0.03
20 68.0 48.0 58.0 0.00
21 61.0 45.0 53.0 0.00
22 74.0 47.0 60.5 0.02
23 71.0 43.0 57.0 0.00
24 82.0 39.0 60.5 0.00
25 87.0 58.0 72.5 0.00
26 90.0 64.0 77.0 0.00
27 87.0 67.0 77.0 0.03
28 88.0 65.0 76.5 0.00
29 87.0 56.0 71.5 0.00
30 88.0 65.0 76.5 0.00
31 85.0 58.0 71.5 0.86
0.94
Extreme High 90.0 Date: 26-May
Extreme Low 39.0 Date: 24-May
Mean Max: 79.7
Mean Low: 53.2
Mean: 66.5
dabour
Days > 90 1.0
Days > 85 11.0
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REISTERSTOWN MARYLAND – MAY 2015 – MONTHLY CLIMATOLOGICAL SUMMARY

MAY 2015 CLIMATOLOGICAL SUMMARY
REISTERSTOWN MARYLAND CITY OFFICE
by Observer in charge/NJWO member Ray Muller

Average maximum temperature 81.0°
Average minimum temperature 59.3°
Average mean temperature 70.2°
High temperature 88° (18/1632 and 31/1551)
Low temperature 44° (14/0605)
Max daily range in temperature 32° 82°-50° (13)
Min daily range in temperature 9° 58°-49° (21)
Min max temperature 58° (21)
Max min temperature 70° (12)
Heating degree days 43
Cooling degree days 211

Monthly precipitation 1.23″
Year-to-date precipitation (through 5/31) 14.38″
Max precipitation in 12 hours 0.46″ (19)
Max precipitation in 24 hours 1.02″ (19)
Number of precipitation days with .01″ or more 4
Number of precipitation days wth .10″ or more 2
Number of precipitation days with .50″ or more 1
Number of precipitation days with 1.00″or more 1

Weather types
Fog 8
Dense Fog 1
Thunder 4
Haze 10

Sky cover
Clear days 8
Partly cloudy days 17
Cloudy days 6
Mean sky cover (sunrise to sunset) 4.8
Estimated percent of possible sunshine 65

Pressure
Highest barometric pressure 30.43″ (23)
Lowest barometric pressure 29.83″ (1)

Winds
Daily prevailing direction West
Mean speed 7.9 MPH
Fastest mile 23 MPH from 280° (31)
Peak wind gust 34 MPH from the W (31/2003) Gale wind days 1
Damaging wind days 0

Relative Humidity
Mean relative humidity
0700 83%
1300 51%
1900 54%
Minimum relative humidity 22% (24/1400)
Maximum relative humidity 100% on 8 separate days, mostly AM

Number of days with cumulonimbus clouds 3
No mammatus clouds observed
Number of days with cloud-to-cloud and cloud-to-ground lightning 3 On the 31st cloud-to-ground lightning strikes were less than a minute apart at times according to my lightning detector.

Summary: another consecutive dry month with very warm,
above normal temperatures.
Record driest month of May for this Reisterstown City Office location.


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MAY 2015 – WEATHER STATION HIGHLIGHTS – GAITHERSBURG 2 WNW MARYLAND

MAY 2015 – WEATHER STATION HIGHLIGHTS – GAITHERSBURG 2 WNW MARYLAND

by Kevin Shaw, Observer-in-charge/NJWO member

This May was a very warm and significantly dry month. But daily records were sparse, except for several
record high minimum temperatures, mostly in the middle third of the month. Despite being one of the
warmest Mays ever, no record high temperatures were set, and I did not hit 90 all month, which has now
happened during 19 Mays in my 37 year period of record. The mean temperature of 69.6 is now the
second warmest May mean temperature ever in my POR (period of record), just missing the 69.7 record
set back in 2004. The average max temperature of 80.3 came in third place, only surpassed by the record
80.5 (2004) and 80.4 (1991). The average min temperature of 58.8 came in a tie with 2004 for second
place, only topped by 59.2 in 2012. One renegade, non-pattern-fitting record was set on a very cool, damp
day towards the end of the month with a 57 high temperature on the 21st, a daily record low maximum
temperature for the date. The 1.54″ of precipitation during the month was the fourth driest ever May in my
37 year POR. With only 8 measurable days of rain this May which was more than 4 days below normal and
fit in well with the much below normal rainfall total. One last bit of information – May 2015’s lowest temp
(46) was the highest monthly May low temperature ever.

The average maximum temperature for the month was 80.3° (+6.0°), the average minimum temperature
was 58.8°(+7.4°) with the resultant mean average temperature for the month of 69.6°(+6.7°). The highest
temperature recorded during the month was a modest 88° on both the 19th and 28th, which did not come
very close to setting or tying a daily record. While we had no days with max temperatures at or above 90,
we had a lot of 80° or over readings (22). Unfortunately I don’t keep track of that particular statistic through
my POR, so I don’t know where it ranks historically, but I am sure it is very close if not at the top of the heap
of the 37 Mays in my POR.

The month’s total precipitation amount of 1.54″ was 2.92″ below the normal May amount of 4.46″. The 8
days of measurable precipitation during the month was well below the long term average of 12.3 days. The
year to date (YTD) precipitation total of 15.42″ now puts us 2.72″ below the normal YTD average amount for
this time of year of 18.14″. No snow fell in May, so the final seasonal snowfall total of 35.8″ was 7.3″ above
the normal total seasonal snowfall amount of 28.5″.

The monthly barometric pressure extremes were a modest 30.48″ on the 23rd and 29.82″ just a few days
before on the 19th. Average barometric pressure for the month was 30.13″, not the same value you would
get if you averaged the two extreme values (30.15″) I had for the month but pretty close. So far with three
months study under my belt, this relationship has shown up as the same in March, 0.06″ difference in April,
and 0.02″ in May. It looks promising for developing some sort of relationship there. Further study needed
the rest of the year (at least).

The distribution of 9 sunny, 14 partly cloudy and 8 cloudy days did not align with the below normal
precipitation pattern, nor the number of days with measurable precipitation, but the preponderance of
warm, humid days during this May did align somewhat.

There was 40 heating degree days and 182 cooling degree days. There were 3 days with fog (below
long-term average) and 4 days with thunder (about average).

My maximum temperature frequencies included 22 days at or above 80°, 6 days between 70°and 79°,
2 days between 60° and 69°, and 1 day from 50°- 59°. On the minimum temperature frequency side of
things, there were 5 days between 40°and 49°, 10 days between 50°-59°, 14 days between 60°-69°,
and 2 days with a 70° min.

The diurnal range average was a bit below normal (21.5° vs the normal 22.9°). The max daily range
of 36.3° occurred on the 4th as headed into our first May heat wave. The lowest daily temperature
range of 6.8° occurred on the 21st during that renegade, isolated cloudy, cool day in between hot
periods discussed earlier. This was the only day of the month with a diurnal range lower than 10°
while there were just 3 days with ranges of 30° or more.

The month of May had persistent warmth and dryness that reflected in the monthly averages but not
in the records, save for the large amount of record high mins as mentioned above. Precipitation deficits
were starting to be of concern by the end of May, but a comparatively wet beginning to the month of
June so far has alleviated that worry for the time being. When will I hit my first 90 maximum temperature?
Hopefully it won’t be for a while. I don’t see it for the foreseeable future as of June 4. My personal
preference would be not to hit 90 all summer. But unfortunately that is not very likely. Details on June
coming in about a month!

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Scientists tackle mystery of thunderstorms that strike at night (PECAN) & No NWS Open House this summer

NWS has informed the NYC/LI Chapter of the AMS that there will be NO NWS Open House this summer. The entire BNL Summer Sundays schedule is listed below.

2015-06 FOR IMMEDIATE RELEASE: May 20, 2015

Scientists tackle mystery of thunderstorms that strike at night
Researchers armed with more than 100 scientific instruments will spend six weeks this summer probing nocturnal thunderstorms on the Great Plains.

Contacts:

David Hosansky, NCAR/UCAR Media Relations
hosansky
303-497-8611

Laura Snider, NCAR/UCAR Media Relations
lsnider
303-497-8605

For additional media contacts, visit http://www2.ucar.edu/atmosnews/news/15575/scientists-tackle-mystery-thunderstorms-strike-night.

BOULDER – Thunderstorms that form at night, without a prod from the Sun’s heat, are a mysterious phenomenon. This summer scientists will be staying up late in search of some answers.

From June 1 through July 15, researchers from across North America will fan out each evening across the Great Plains, where storms are more common at night than during the day. The research effort, co-organized by the National Center for Atmospheric Research (NCAR) and several collaborating institutions, will use lab-equipped aircraft, ground-based instruments, and weather balloons to better understand the atmospheric conditions that lead to storm formation and evolution after sunset.

Their results may ultimately help improve forecasts of these sometimes damaging storms.

The Plains Elevated Convection at Night (PECAN) field campaign will involve scientists, students, and support staff from eight research laboratories and 14 universities. The $13.5 million project is largely funded by the National Science Foundation (NSF), NCAR’s sponsor, which contributed $10.6 million. Additional support is provided by NASA, the National Oceanic and Atmospheric Administration (NOAA), and the U.S. Department of Energy.

Aloft in the night

Thunderstorms that form during the day are less puzzling than nighttime storms. The Sun heats the Earth’s surface, which in turn, warms the air directly above the ground. When that warm air is forced to rise, it causes convection—a circulation of warm updrafts and cool downdrafts—and sometimes creates a storm.

The formation of thunderstorms at night, however, when the Sun is not baking the land, is less well understood.

"At night, the entire storm circulation is elevated higher off the ground," said NCAR scientist Tammy Weckwerth, a PECAN principal investigator. "This makes observations of the conditions leading to nighttime thunderstorms much more challenging because that part of the atmosphere is not well covered by the network of instruments we normally rely on."

The vast array of instruments available to PECAN researchers will allow them to collect data higher in the atmosphere. This data will help scientists characterize the conditions that lead both to individual storm formation as well as to the clustering and organizing of these storms into large-scale systems, which can drop significant precipitation.

"Nighttime thunderstorms are an essential source of summer rain for crops but are also a potential hazard through excessive rainfall, flash flooding, and dangerous cloud-to-ground lightning," says Ed Bensman, program director in NSF’s Division of Atmospheric and Geospace Sciences. "Weather forecast models often struggle to accurately account for this critical element of summer rainfall on the Great Plains. The PECAN field campaign will provide researchers and operational forecasters with valuable insights into thunderstorms at night—and improve our ability to model them more accurately."

Deploying in the dark

The campaign, based in Hays, Kansas, will begin each day at 8 a.m., when a crew of forecasters starts developing a nightly forecast. At 3 p.m. the scientists will use the forecast to determine where across northern Oklahoma, central Kansas, or south-central Nebraska to deploy their mobile resources. Moving dozens of people around the Great Plains each night will be a challenge for PECAN, but it’s also what distinguishes it from past field projects.

"Previous severe weather campaigns have focused mostly on daytime storms, for largely practical reasons, as it is more difficult to set up instruments in the dark," said Bart Geerts, a professor of atmospheric science at the University of Wyoming and a PECAN principal investigator. "But the large thunderstorm complexes travelling across the Great Plains at night really are a different beast."

Scientists believe that several interacting factors may contribute to nocturnal storm formation and maintenance: a stable layer of air at the surface; a strong wind current above that layer, known as a low-level jet; and atmospheric waves, some of which are called "bores," that ripple out from the storms themselves.

"But we just don’t really know how they interact," Geerts said. "That’s what PECAN is about."

A better understanding of these storms will have relevance for areas beyond the Great Plains. Clustered nighttime thunderstorms are common in various regions scattered across the globe.

A fleet of instruments

PECAN will use three research aircraft, two of which—a University of Wyoming King Air and a NASA DC-8—will fly in the clear air away from the storms. Only the third, a NOAA P-3, which is widely used in hurricane research and reconnaissance, will be able to fly into the trailing region of storms.

The researchers will also rely on a number of ground-based instrument suites, known as PECAN Integrated Sounding Arrays, or PISAs. Six of the PISAs will operate from fixed locations around the study area, and four will be mobile, allowing them to be repositioned each night depending on where storms are expected to form.

The instruments within each PISA vary, but collectively they will give each array the ability to measure temperature, moisture, and wind profiles, as well as launch weather balloons. Among the instruments are several newly developed at NCAR’s Earth Observing Laboratory (EOL), including one that uses an innovative laser-based technique to remotely measure water vapor and an advanced wind profiler.

Finally, the scientists will have a fleet of mobile and fixed radars, including the NCAR S-Pol. In all, PECAN researchers will have access to more than 100 instruments brought to the effort by partner institutions from across North America.

"The sheer number of instruments being coordinated is unprecedented," said Weckwerth, who has participated in more than 15 other field expeditions.

The planning necessary to manage this large collection of instruments—from finding property suitable for a fixed radar to making sure the mobile instruments are out of harm’s way while tracking a storm—is being taken on by EOL’s Project Management Office. That team is also responsible for housing, food and other logistics for the scientists and students who are participating in the campaign.

On the Web

PECAN
www.eol.ucar.edu/field_projects/pecan

Mark Kramer, Chair

New York City/Long Island AMS Chapter

nycliams

http://www.nws.bnl.org/meetings.html

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July 12 – August 2, 2015

For several weeks each summer, Brookhaven Lab welcomes members of the public to its site. We plan days that include visits to our facilities, opportunities to speak with our researchers, special activities for adults and children, and much more—and it’s all free!

July 12

Exploring the Ultra Small

Visit the Center for Functional Nanomaterials, where Brookhaven researchers probe structures as tiny as a billionth of a meter. Learn about scientists’ latest discoveries in innovative energy technologies. Be amazed by "Atoms, Molecules, Matter and More!"

July 19

Brilliant Light, Dazzling Discoveries

Tour the National Synchrotron Light Source II, the world’s brightest synchrotron light source! Learn how scientists will illuminate the inner workings of batteries and seek answers to some of the nation’s toughest energy challenges. Be enlightened by the "Science Laser Light Spectacular."

July 26

Family Fun Day

A fabulous day of hands-on family fun! Use the basic scientific method to explore magnets, mirrors, and more! Hop aboard a fire truck and learn all about the Laboratory’s protective services. Be mystified by the "The Mystery & History of Magic."

August 2

Atom-Smashing Fun*

Visit the Relativistic Heavy Ion Collider, a world-class particle accelerator where physicists recreate the conditions of the universe as they believe it existed microseconds after the Big Bang! Stump a physicist and meet "Einstein" alive.

* Facility tour appropriate for ages 10 and over.

FREE! No reservations needed.

  • Gates open 10 a.m.—3 p.m.
  • All activities are available on a first-come, first-served basis.
  • Visitors age 16 and over must bring a photo ID.
  • Handicapped accessible
  • 1-1/2 miles north of LIE Exit 68
    Maps & Directions to Brookhaven Lab
  • Call (631) 344-2651
  • Visit the Summer Sundays Facebook page to receive monthly updates.
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NJWO Blog submission — Jeff Permuy

Hi, Dave…

Enclosed is the WS article I submitted for the March edition. Also attached is the photo I used for the article (embedded in the Word doc). I can submit the article used in the WS May edition later.

Thanks,
Jeff

WS article_02-23-15 (Jeff Permuy).docx

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