ACUS02 KWNS 240553 SWODY2 SPC AC 240551 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1251 AM CDT FRI MAY 24 2013 VALID 251200Z - 261200Z ...THERE IS A SLGT RISK OF SVR TSTMS FOR A PORTION OF ERN MT / FAR NERN WY / WRN DAKOTAS... ...SYNOPSIS... THE UPPER AIR PATTERN WILL FEATURE A WRN U.S. TROUGH/CNTRL U.S. RIDGE/ERN U.S. TROUGH. DOWNSTREAM OF THE WRN STATES TROUGH...A BROAD BELT OF MODERATE SWLY MID-LEVEL FLOW WILL OVERSPREAD THE NRN HIGH PLAINS. A LEE SURFACE TROUGH OVER MUCH OF THE HIGH PLAINS WILL SERVE AS A FOCUS FOR AFTERNOON/EVENING STORM DEVELOPMENT. FARTHER E...A FRONTAL ZONE WILL EXTEND FROM THE ERN DAKOTAS TO THE MID MS VALLEY TO THE WEST OF SURFACE HIGH PRESSURE CENTERED OVER THE GREAT LAKES. ...NRN HIGH PLAINS INTO THE MID MO VALLEY... NWD MOISTURE RETURN INTO THE CNTRL-NRN PLAINS ON THE BACKSIDE OF THE MIDWEST SURFACE HIGH WILL BE ONGOING AT THE START OF THE DAY 2 PERIOD AS A CLOSED MID-LEVEL LOW REMAINS CENTERED OVER SRN BRITISH COLUMBIA. THE LEE TROUGH LOCATED OVER CNTRL MT WILL ACT TO DRAW 50S DEWPOINTS WESTWARD INTO ERN MT AND UPPER 50S DEWPOINTS INVOF THE BLACK HILLS...CONTRIBUTING TO MARGINAL-MODERATE INSTABILITY. STRONG DIURNAL HEATING WILL SEEMINGLY LEAD TO ISOLD TO WIDELY SCTD STORMS IN THE LATE AFTERNOON-MID EVENING. DEEPLY VEERING WIND PROFILES /40+ KT EFFECTIVE SHEAR/ WOULD SUPPORT STORM ORGANIZATION...INCLUDING SUPERCELLS WITH ISOLD LARGE HAIL/WIND GUSTS BEING THE PRIMARY HAZARDS. FARTHER SE OVER THE MID MO VALLEY...THE TERMINUS OF A CNTRL PLAINS 30 KT LLJ WILL FOCUS OVER THE MID MO VALLEY THROUGHOUT THE DAY. ALTHOUGH THIS REGION IS BENEATH THE UPPER RIDGE AXIS...AT LEAST A LOW RISK FOR STORMS IS SUPPORTED BY VARIOUS OPERATIONAL MODELS. GIVEN MODERATE INSTABILITY DEPICTED BY MODEL FORECAST SOUNDINGS...A CONDITIONAL SEVERE AREA HAS BEEN INCLUDED THIS FORECAST UPDATE. ...PORTION OF THE SRN HIGH PLAINS... A SELY LOW LEVEL FETCH OF MOISTURE LOCATED OVER THE SRN PLAINS IS FORECAST TO MOVE WESTWARD INTO THE SRN HIGH PLAINS IN CONCERT WITH THE LEE TROUGH...ABUTTING NEXT TO THE HIGHER TERRAIN IN W TX AND THE ERN PLAINS OF NM. STEEP MID LEVEL LAPSE RATES EMANATING FROM THE W AND STRONG DAYTIME HEATING WILL ACT TO FAVOR ISOLD STORM DEVELOPMENT BY AFTERNOON...INITIALLY FAVORING HIGHER TERRAIN. DESPITE ONLY 20 KT WLY H5 FLOW...STRONGLY VEERING WIND PROFILES WOULD SUPPORT SOME STORM ORGANIZATION FEATURING MAINLY HIGHER-BASED MULTICELLULAR STORMS CAPABLE OF PERHAPS A FEW SEVERE WIND GUSTS AND MARGINALLY SEVERE HAIL. THIS ACTIVITY SHOULD WEAKEN DURING THE EVENING HOURS COINCIDENT WITH A STABILIZING BOUNDARY LAYER.. ..SMITH.. 05/24/2013
