Download Storm Prediction Center Aug 21, 2014 2000 UTC Day 1 Convective

Storm Prediction Center Aug 21, 2014 2000 UTC Day 1 Convective Outlook
12/12/14 12:36 PM
Aug 21, 2014 2000 UTC Day 1 Convective Outlook
Updated: Thu Aug 21 20:05:54 UTC 2014 (
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Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
Risk
SLIGHT
Area (sq. mi.)
241,344
Area Pop.
48,895,272
Some Larger Population Centers in Risk Area
Chicago, IL...Philadelphia, PA...Indianapolis, IN...Columbus, OH...Baltimore, MD...
Probabilistic Tornado Graphic
http://tornado.sfsu.edu/geosciences/classes/m302/ConvectiveOutlooks/SlightRisk/SlightRisk_August_21_2014.html
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Storm Prediction Center Aug 21, 2014 2000 UTC Day 1 Convective Outlook
12/12/14 12:36 PM
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Tornado Risk
2%
Area (sq. mi.)
106,089
Area Pop.
33,756,087
Some Larger Population Centers in Risk Area
Chicago, IL...Philadelphia, PA...Baltimore, MD...Milwaukee, WI...Washington, DC...
Probabilistic Damaging Wind Graphic
http://tornado.sfsu.edu/geosciences/classes/m302/ConvectiveOutlooks/SlightRisk/SlightRisk_August_21_2014.html
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Storm Prediction Center Aug 21, 2014 2000 UTC Day 1 Convective Outlook
12/12/14 12:36 PM
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Wind Risk
15 %
5%
Area (sq. mi.)
240,738
442,774
Area Pop.
48,757,210
53,749,928
Some Larger Population Centers in Risk Area
Chicago, IL...Philadelphia, PA...Indianapolis, IN...Columbus, OH...Baltimore, MD...
Phoenix, AZ...Atlanta, GA...Minneapolis, MN...Pittsburgh, PA...Toledo, OH...
Probabilistic Large Hail Graphic
http://tornado.sfsu.edu/geosciences/classes/m302/ConvectiveOutlooks/SlightRisk/SlightRisk_August_21_2014.html
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Storm Prediction Center Aug 21, 2014 2000 UTC Day 1 Convective Outlook
12/12/14 12:36 PM
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Hail Risk
15 %
5%
Area (sq. mi.)
179,964
365,724
Area Pop.
39,475,100
51,652,352
Some Larger Population Centers in Risk Area
Chicago, IL...Philadelphia, PA...Indianapolis, IN...Baltimore, MD...Washington, DC...
Phoenix, AZ...Columbus, OH...Milwaukee, WI...Mesa, AZ...Minneapolis, MN...
SPC AC 212005
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0305 PM CDT THU AUG 21 2014
VALID 212000Z - 221200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER MS VALLEY INTO
THE OH VALLEY...
...THERE IS A SLGT RISK OF SVR TSTMS OVER PART OF THE MID-ATLANTIC
STATES...
...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF SERN CA INTO
SWRN AZ...
...SUMMARY...
SCATTERED STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED FROM PORTIONS
OF THE UPPER MISSISSIPPI VALLEY INTO THE OHIO VALLEY AND CENTRAL
APPALACHIANS. DAMAGING WINDS AND LARGE HAIL ARE THE PRIMARY THREATS
WITH THIS ACTIVITY. STORMS WITH LARGE HAIL AND STRONG WINDS WILL
ALSO BE POSSIBLE ACROSS THE LOWER COLORADO RIVER VALLEY. SCATTERED
STRONG TO SEVERE STORMS WILL ALSO REMAIN POSSIBLE INTO THE EARLY
EVENING ACROSS PORTIONS OF THE MIDDLE ATLANTIC STATES FROM SOUTHEAST
PENNSYLVANIA INTO NORTHERN AND CENTRAL MARYLAND...WASHINGTON D.C. TO
DELAWARE AND SOUTHERN NEW JERSEY.
...MID-ATLANTIC STATES...
A SLIGHT RISK HAS BEEN INTRODUCED ACROSS THIS REGION AND INCLUDES
THE METRO AREAS OF PHILADELPHIA...BALTIMORE AND THE DISTRICT OF
COLUMBIA. VAD WINDS SHOWED SOME STRENGTHENING OF WLY 500 MB WINDS
/AT 35 KT/ ENHANCING BULK SHEAR FOR STORM ORGANIZATION EWD FROM AND
INCLUDING SRN PA AND NRN MD. MODERATE INSTABILITY ACROSS THIS
REGION COMBINED WITH THE STRONGER BULK SHEAR IS EXPECTED TO SUPPORT
ADDITIONAL STRONG TO SEVERE STORMS DEVELOPING AND SPREADING SEWD.
...SRN MN/WRN WI...
LOW-LEVEL STRATUS CLOUDS OVER PORTIONS OF CENTRAL MN INCLUDING THE
NRN TWIN CITIES METRO AND WEST CENTRAL WI WILL TEND TO INHIBIT
SURFACE HEATING/DESTABILIZATION THROUGH THE REST OF THE AFTERNOON.
TSTMS REMAIN POSSIBLE PER 4KM NAM AND 4KM NSSL MODELS WITHIN THE
WARM SECTOR IN SRN MN. THIS OUTLOOK HAS SHIFTED THE NRN PORTION OF
THE SLIGHT RISK IN SRN MN AND WRN WI SWD A FEW COUNTIES.
...ERN KY/FAR SWRN VA...
THE SLIGHT RISK HAS BEEN EXPANDED A LITTLE TO INCLUDE MORE OF SERN
KY AND FAR SWRN VA GIVEN CONVECTIVE TRENDS AND SIMILAR VALUES OF
MODERATE TO STRONG INSTABILITY PER OBJECTIVE ANALYSES.
...ERN AL AND WRN/CENTRAL GA...
STORMS WILL CONTINUE TO DEVELOP ACROSS THESE REGIONS THROUGH THE
AFTERNOON TO EARLY EVENING WHERE THE ENVIRONMENT HAS BECOME VERY
UNSTABLE /MLCAPE EXCEEDING 3000 J PER KG/. WEAK DEEP LAYER SHEAR
WILL TEND TO LIMIT STORM ORGANIZATION...WITH STRONG WIND GUSTS BEING
THE PRIMARY THREATS.
http://tornado.sfsu.edu/geosciences/classes/m302/ConvectiveOutlooks/SlightRisk/SlightRisk_August_21_2014.html
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Storm Prediction Center Aug 21, 2014 2000 UTC Day 1 Convective Outlook
12/12/14 12:36 PM
THE PRIMARY THREATS.
...REST OF THE FORECAST...
NO OTHER SIGNIFICANT CHANGES HAVE BEEN MADE TO THIS OUTLOOK.
..PETERS.. 08/21/2014
.PREV DISCUSSION... /ISSUED 1129 AM CDT THU AUG 21 2014/
...UPPER MS VALLEY THROUGH THE GREAT LAKES AND OH VALLEY...
HEIGHTS WILL RISE AND SHORTWAVE RIDGING WILL BUILD EWD TOWARD THE
GREAT LAKES. HOWEVER...SATELLITE DATA AND RUC ANALYSIS SHOW A COUPLE
OF VORTICITY MAXIMA...ONE LOCATED OVER WI AND ANOTHER OVER WRN IA.
WIDESPREAD CLOUDS AND THUNDERSTORMS DEVELOPING WITHIN ZONE OF WARM
ADVECTION CONTINUES FROM IA AND WI THROUGH NRN IL AND SEWD THROUGH
OH. CLOUD COVER IS MUCH MORE LIMITED IN WARM SECTOR TO THE SOUTH OF
THIS ACTIVITY WHERE DEWPOINTS ARE AROUND 70F. DIABATIC WARMING WILL
DESTABILIZE THE BOUNDARY LAYER THIS AFTERNOON WITH MLCAPE FROM
2000-3000 J/KG LIKELY. POTENTIAL EXISTS FOR STORMS TO REDEVELOP AND
INTENSIFY LATER OVER THE OH VALLEY TODAY AS MOIST SWLY INFLOW FROM
THE DESTABILIZING WARM SECTOR INTERACTS WITH THE NW-SE ORIENTED
CONVECTIVELY REINFORCED BAROCLINIC ZONE. STORMS MAY SUBSEQUENTLY
EVOLVE INTO CLUSTERS AS THEY DEVELOP SEWD WITH A THREAT FOR ISOLATED
DAMAGING WIND AND HAIL. OTHER STRONG TO SEVERE STORMS MAY DEVELOP
FARTHER NORTH IN MN NEAR THE WARM FRONT-COLD FRONT INTERSECTION.
...EXTREME SERN CA AND SWRN AZ...
PER SATELLITE IMAGERY AND GPS PW DATA...A MOISTURE PLUME ORIGINATING
FROM T.S. LOWELL HAS BEEN ENTRAINED INTO THE EASTERN FLANK OF A
CLOSED LOW MOVING SLOWLY EAST TOWARD THE LOWER CO RIVER VALLEY. LIFT
AND COLDER AIR ALOFT ACCOMPANYING THE MID/UPPER LOW...IN CONCERT
WITH DIURNAL HEATING...WILL LIKELY RESULT IN A CORRIDOR OF GREATER
DESTABILIZATION AND THUNDERSTORM DEVELOPMENT ACROSS THE LOWER CO
RIVER VALLEY LATER TODAY. IN ADDITION TO LOCALLY STRONG WIND GUSTS
GIVEN HIGH DCAPE...SPC HAIL MODEL APPLIED TO FORECAST SOUNDINGS FROM
THE NAM AND WRF-ARW INDICATE THE POSSIBILITY OF SEVERE HAIL TO AT
LEAST 1 INCH IN DIAMETER. WHILE THE AREAL EXTENT OF THE SEVERE STORM
THREAT MAY REMAIN CONFINED...ENVIRONMENT APPEARS SUFFICIENT ENOUGH
TO WARRANT SLGT RISK 15 PERCENT HAIL/WIND PROBABILITIES.
...MID ATLANTIC AREA...
BACKGROUND CYCLONIC FLOW AND WEAK DPVA AMIDST A PLUME OF RELATIVELY
HIGH PW SHOULD FOSTER SCATTERED LOOSELY-ORGANIZED THUNDERSTORMS OVER
NY/PA AND DELMARVA THIS AFTERNOON. A BELT OF SOMEWHAT STRONGER
MID-LEVEL FLOW FORECAST FROM SOUTHEAST NY ACROSS PA/NJ MAY
CONTRIBUTE TO SLIGHTLY MORE ORGANIZED/PERSISTENT STORMS IN THESE
AREAS. WHILE A COUPLE OF STRONGER CONVECTIVE WIND GUSTS WILL BE
POSSIBLE AROUND THE TIME OF PEAK HEATING...WEAK LAPSE RATES AND
MODEST INSTABILITY SUGGEST THE SEVERE WIND GUST POTENTIAL SHOULD
REMAIN LIMITED.
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
http://tornado.sfsu.edu/geosciences/classes/m302/ConvectiveOutlooks/SlightRisk/SlightRisk_August_21_2014.html
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