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Mar 12, 2014 0600 UTC Day 1 Convective Outlook

March 12, 2014

Mar 12, 2014 0600 UTC Day 1 Convective Outlook

day1otlk

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1253 AM CDT WED MAR 12 2014

VALID 121200Z – 131200Z

…THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF CNTRL APPALACHIAN MTNS AND MID-ATLANTIC STATES…

…CNTRL APPALACHIAN MTNS/MID-ATLANTIC…
AN UPPER-LEVEL TROUGH EXTENDING FROM THE UPPER GREAT LAKES SWD INTO THE MID MS VALLEY WILL MOVE EWD ACROSS THE OH AND TN VALLEYS TODAY. A 90 TO 100 KT MID-LEVEL JET IN THE BASE OF THE UPPER-LEVEL TROUGH WILL MOVE EWD ACROSS THE SRN APPALACHIAN MTNS. AT THE SFC…A DEEPENING LOW WILL TRACK INTO THE MID-ATLANTIC AS A TRAILING COLD FRONT ADVANCES EWD ACROSS THE SRN AND CNTRL APPALACHIAN MTNS. CONVECTION SHOULD BE ONGOING AT THE START OF THE PERIOD ALONG AND JUST AHEAD OF THE COLD FRONT FROM SRN OH SSWWD ACROSS ERN KY AND ERN TN. THIS CONVECTION IS FORECAST BY THE HI-RES MODELS TO MOVE EWD AND ORGANIZE INTO A LINE…AFFECTING THE HIGHEST ELEVATIONS OF THE CNTRL APPALACHIAN MTNS IN THE EARLY AFTERNOON AND AFFECTING THE APPALACHIAN FOOTHILLS TO THE EAST OF THE CREST BY THE MID AFTERNOON. IT APPEARS THAT THE LINE OF THUNDERSTORMS WILL MOVE QUICKLY EWD INTO THE MID-ATLANTIC BY LATE AFTERNOON.

NAM FORECAST SOUNDINGS AT 21Z FROM NEAR HAGERSTOWN MD SSWWD TO NEAR CHARLOTTESVILLE VA SHOW A STRONG WIND SHEAR ENVIRONMENT WITH VEERED WINDS AT THE SFC AND 50 KT OF WSWLY FLOW ABOVE 850 MB. THIS ALONG WITH A UNIDIRECTIONAL COMPONENT ABOVE THE BOUNDARY LAYER SHOULD BE FAVORABLE FOR STRONG OUTFLOW GUSTS AS THE CONVECTIVE LINE MOVES ACROSS THE REGION THIS AFTERNOON. THE MAIN CONCERN FOR SEVERE THREAT COVERAGE IS DESTABILIZATION. THE WRF-HRRR DEVELOPS SOME FAIRLY WIDESPREAD RAINFALL ACROSS CNTRL AND NRN VA EXTENDING NWD INTO SRN PA WHICH COULD LIMIT DESTABILIZATION IN SOME AREAS. THE NAM HAS TWO POCKETS OF INSTABILITY…THE FIRST IN WRN MD AND THE SECOND IN NRN NC SUGGESTING LOCALIZED HEATING SHOULD BE A FACTOR IN CREATING THE GREATEST SEVERE THREAT WITH THE LINE. AS THE LINE MOVES INTO MD AND CNTRL VA…ENHANCEMENT FROM THE LEFT EXIT REGION OF THE MID-LEVEL JET…STRONG LARGE-SCALE ASCENT AND IMPRESSIVE WIND FIELDS SHOULD CREATE A WELL-DEVELOPED FINE LINE. ALTHOUGH THE MAIN THREAT SHOULD BE DAMAGING WIND GUSTS…A FEW TORNADOES CAN NOT BE RULED OUT WITH ROTATING CELL ELEMENTS ASSOCIATED WITH BOWING LINE SEGMENTS. THE WIND DAMAGE THREAT MAY CONTINUE AS FAR EAST AS THE COAST OF VA AND NJ BY EARLY EVENING. THE SRN EXTENT OF THE SEVERE THREAT IS QUESTIONABLE AND MAY DEPEND UPON HOW MUCH LOW-LEVEL CONVERGENCE DEVELOPS ALONG THE FRONT. A FEW DAMAGING WIND GUSTS MAY OCCUR ACROSS NCNTRL NC IF THE LINE CAN ORGANIZE THAT FAR SOUTH.

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