Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 211732
SWOMCD
SPC MCD 211731
VAZ000-MDZ000-DCZ000-211930-

MESOSCALE DISCUSSION 1573
NWS STORM PREDICTION CENTER NORMAN OK
1231 PM CDT SUN AUG 21 2016

AREAS AFFECTED...WASHINGTON DC...PARTS OF MD...NRN/CNTRL/ERN VA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 211731Z - 211930Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THE POTENTIAL FOR ISOLATED STRONG TO DMGG WIND GUSTS IS
EXPECTED TO INCREASE THROUGH MID-AFTERNOON ACROSS PARTS OF MD AND
VA...AND WASHINGTON DC. A WATCH IS POSSIBLE.

DISCUSSION...SATELLITE TRENDS SHOW AN INCREASING CU FIELD NEAR THE
BLUE RIDGE MTNS OF NRN VA ALONG THE ERN EDGE OF A CLOUD SHIELD
COVERING MOST OF THE CNTRL APPALACHIANS. OTHER SHOWERS ARE
DEVELOPING ACROSS ERN VA INTO NERN MD ALONG A WEAK CONVERGENCE LINE.
COLD FRONT/WIND SHIFT APPEARS TO BE LAGGING TO THE W...WITH RECENT
DEVELOPMENT LIKELY DRIVEN BY OROGRAPHIC EFFECTS/DIURNAL HEATING.
MEANWHILE...TEMPERATURES HAVE HEATED INTO THE MID-UPPER 80S ACROSS
NRN VA...AND IN THE UPPER 70S F ACROSS MD AMIDST THICKER CLOUDINESS.
VERY RICH TROPOSPHERIC MOISTURE...WITH PW VALUES ABOVE 2 INCHES AND
SFC DEWPOINTS IN THE LOW 70S F...IS SUPPORTING A CORRIDOR OF MLCAPE
VALUES NEAR 1500 J/KG ACROSS ERN PORTIONS OF VA INTO SRN
MD...DESPITE POOR LAPSE RATES ALOFT. WITH SLIGHTLY VEERED SSWLY
WINDS E OF THE HIGHER TERRAIN...LOW-LEVEL CONVERGENCE IS EXPECTED TO
GENERALLY BE WEAK WHICH MAY LIMIT THE POTENTIAL FOR A MORE
ORGANIZED/WIDESPREAD WIND THREAT. HOWEVER...MODERATE WLY FLOW ALOFT
IS YIELDING EFFECTIVE SHEAR VALUES AROUND 30 KT...FAVORABLE FOR A
FEW MULTICELL CLUSTERS CAPABLE OF ISOLATED STRONG TO DMGG WIND
GUSTS. DEEP-LAYER SHEAR GRADUALLY WEAKENS FARTHER SWD INTO VA...BUT
ISOLATED STRONG WIND GUSTS STILL REMAIN POSSIBLE GIVEN THE HOT/MOIST
BOUNDARY LAYER.

CONVECTIVE TRENDS WILL BE MONITORED FOR INCREASING DMGG WIND
POTENTIAL OVER THE NEXT 1-2 HRS...IN WHICH CASE A WATCH MAY BE
CONSIDERED FOR PARTS OF NRN/CNTRL/ERN VA AND MD...AND WASHINGTON DC.

..ROGERS/THOMPSON.. 08/21/2016

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...AKQ...LWX...RNK...

LAT...LON   39297656 38417648 37587642 36997702 36797772 37057819
            37947857 38667837 39607719 39527684 39297656




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