DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 231954
SWODY1
SPC AC 231952

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0252 PM CDT FRI AUG 23 2013

VALID 232000Z - 241200Z

...NO SVR TSTM AREAS FORECAST...

NO CHANGES ARE MADE TO THE OUTLOOK FOR THIS ISSUANCE.

..BROYLES.. 08/23/2013

.PREV DISCUSSION... /ISSUED 1119 AM CDT FRI AUG 23 2013/

...SYNOPSIS...
THE DOMINANT WEATHER FEATURE IS A MID-UPPER LEVEL HIGH OVER THE
CENTRAL STATES...WITH AN UPSTREAM TROUGH OVER THE PAC NW...AND A
DOWNSTREAM TROUGH OVER THE UPPER OH VALLEY AND CENTRAL APPALACHIANS.
THE APPALACHIANS WAVE WILL PROGRESS ESEWD TO THE MID ATLANTIC COAST
BY TONIGHT AS AN ASSOCIATED SURFACE COLD FRONT MOVES SWD ACROSS THE
OH VALLEY AND MID ATLANTIC STATES. MEANWHILE...THE MONSOONAL
MOISTURE PLUME WILL PERSIST FROM NW MEXICO TO THE ERN GREAT BASIN.
CONVECTION WILL BE MORE CONCENTRATED TODAY ACROSS CENTRAL UT...IN
ADVANCE OF A WELL-DEFINED MCV MOVING NNEWD FROM NW AZ TO SW UT THIS
MORNING.

...SE VA TO CENTRAL NC THIS AFTERNOON...
A BAND OF LOW-MIDLEVEL ASCENT AND ASSOCIATED CLOUDS/RAINFALL WILL
CONTINUE TO SPREAD ESEWD THIS AFTERNOON ACROSS VA...IN ADVANCE OF
THE MIDLEVEL TROUGH OVER WV. IMMEDIATELY SE OF THE THICKER CLOUDS
AND INVOF A DIFFUSE PRE-FRONTAL TROUGH...STRONGER SURFACE HEATING
WILL BOOST MLCAPE VALUES TO 1000-2000 J/KG...DESPITE POOR MIDLEVEL
LAPSE RATES SHOWN IN REGIONAL 12Z SOUNDINGS. THE MODERATE BUOYANCY
AND SOMEWHAT STRONGER DEEP-LAYER VERTICAL SHEAR ACROSS SE VA WILL
SUPPORT A RISK FOR ORGANIZED STORMS/CLUSTERS CAPABLE OF PRODUCING
ISOLATED STRONG DOWNBURST WINDS THIS AFTERNOON.
HOWEVER...WIDESPREAD AND/OR INTENSE SEVERE STORMS ARE NOT
ANTICIPATED.

...SW INTO CENTRAL MT AREA THIS AFTERNOON...
A WEAKENING SHORTWAVE TROUGH OVER THE ID PANHANDLE WILL PROGRESS
NEWD TODAY OVER NW MT...THEN ENEWD OVER SRN AB/SK OVERNIGHT ON THE
NWRN PERIPHERY OF THE CENTRAL US RIDGE. LOW-LEVEL MOISTURE AND
BUOYANCY WILL REMAIN RATHER MODEST ACROSS CENTRAL/WRN MT TODAY...BUT
DAYTIME HEATING WILL RESULT IN A DEEP BOUNDARY LAYER AND STEEP
LOW-LEVEL LAPSE RATES. THE NET RESULT SHOULD BE AN ENVIRONMENT
SUPPORTIVE OF THUNDERSTORM DEVELOPMENT THIS AFTERNOON OVER THE
HIGHER TERRAIN OF W/SW MT...AND THE HIGH-BASED STORMS WILL THEN
SPREAD NEWD TOWARD CENTRAL MT BY THIS EVENING. GIVEN A MODEST
INCREASE IN MIDLEVEL SWLY FLOW AND INVERTED-V THERMODYNAMIC
PROFILES...ISOLATED STRONG/DAMAGING GUSTS WILL BE POSSIBLE.

...WRN ND THIS AFTERNOON...
LEE CYCLOGENESIS WILL CONTINUE ACROSS ERN MT...ALLOWING AN AIR MASS
WITH 60S DEWPOINTS TO SPREAD NWD ACROSS THE DAKOTAS IN CONJUNCTION
WITH THE NWD PROGRESS OF A SURFACE WARM FRONT. A FEW STRONG STORMS
COULD OCCUR ACROSS WRN/CENTRAL ND WITHIN THE MOISTENING WAA
REGIME...BUT ONLY LOW WIND/HAIL PROBABILITIES ARE WARRANTED GIVEN
MODEST VERTICAL SHEAR AND UNCERTAINTY REGARDING STORM COVERAGE.

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