Post by SKYSUMMIT on Mar 31, 2008 6:33:41 GMT -6
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1257 AM CDT MON MAR 31 2008
VALID 011200Z - 021200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF EAST TX ACROSS
THE LOWER MS VALLEY...
...SYNOPSIS...
STRONG AND PROGRESSIVE SHORT WAVE TROUGH NOW CROSSING THE FOUR
CORNERS REGION WILL SUPPORT A DEEPENING SURFACE CYCLONE TRACKING
FROM THE GREAT LAKES INTO ERN CANADA ON TUESDAY. IN THE WAKE OF THIS
SYSTEM...MID LEVEL FLOW ACROSS THE CONUS IS FORECAST TO DEAMPLIFY
BUT REMAIN MODERATELY STRONG IN MAGNITUDE OVER MOST AREAS FROM COAST
TO COAST.
A COLD FRONT WILL EXTEND SWWD FROM THE SURFACE LOW NEAR LAKE HURON
EARLY TUESDAY. GIVEN POTENT AND STRENGTHENING DEEP-LAYER WIND FIELDS
WITH UP TO 120KT AT 500MB...THE FRONT WILL SPREAD RAPIDLY EAST
ACROSS THE ERN GREAT LAKES AND CNTRL APPALACHIANS THROUGH THE DAY
BEFORE MOVING ACROSS THE NORTHEAST AND MID ATLANTIC AREAS AFTER
DARK. THE TRAILING PORTION OF THE DEEP-LAYER FRONTAL ZONE WILL
SETTLE MORE SLOWLY SEWD TOWARD THE TN AND LOWER MS VALLEYS...AND
SHOULD BE SITUATED ALONG A WRN NC TO EAST TX LINE BY TUESDAY
EVENING.
...ERN TX/LOWER MS VALLEY/SOUTH...
AREAS OF POTENTIALLY STRONG DESTABILIZATION ARE LIKELY TO DEVELOP
WITHIN VERY MOIST AND WARM SPRINGTIME AIRMASS FROM THE TN VALLEY
SWWD TO TX DURING THE DAY. DESPITE POCKETS OF MUCAPE OF 1000-2000 J
PER KG ACROSS THESE AREAS...MID LEVEL LAPSE RATES ARE NOT FORECAST
TO BE PARTICULARLY STEEP AND SYNOPTIC SCALE ASCENT WILL BE WANING.
HOWEVER...MODEL GUIDANCE INDICATES THAT A SMALL MCS MAY BE SUSTAINED
FROM LATE MONDAY INTO EARLY TUESDAY NEAR FRONT/LLJ INTERSECTION
ACROSS PARTS OF THE LOWER MS VALLEY. THIS EARLY/LEADING CONVECTION
MAY WEAKEN OR DECAY BEFORE BEING FOLLOWED BY ADDITIONAL DEVELOPMENT
ALONG THE SLOWLY ADVANCING FRONTAL CIRCULATION AND OUTFLOW AS
DIURNAL DESTABILIZATION IS MAXIMIZED THROUGH THE AFTERNOON.
GENERALLY WEAK EFFECTIVE BULK SHEAR AND LACK OF LARGE SCALE ASCENT
SHOULD BE OFFSET BY MAGNITUDE OF INSTABILITY AND LOCALLY ENHANCED
SHEAR/FORCING ON THE FRONT...AND NEAR FRONT/BOUNDARY
INTERSECTIONS...FROM TX ACROSS THE LOWER MS VALLEY INTO EARLY
EVENING. DAMAGING WINDS AND PERHAPS MARGINALLY SEVERE HAIL WILL BE
POSSIBLE WITH THIS ACTIVITY.
...ERN GREAT LAKES/NORTHEAST...
AS INTENSIFYING LOW PRESSURE MOVES FROM LAKE HURON TO THE ST.
LAWRENCE SEAWAY...INTENSE DYNAMIC FORCING FOR ASCENT WILL ACCOMPANY
THE COLD FRONT DEVELOPING RAPIDLY EAST FROM OH...ACROSS PA/NY...AND
INTO NEW ENGLAND. LOW-TOPPED CONVECTION WITH LITTLE IN THE WAY OF
LIGHTNING COULD PRODUCE DAMAGING WINDS WITHIN THE HIGHLY SHEARED/LOW
INSTABILITY REGIME. DYNAMIC SITUATION HAS SIMILARITIES TO THE LATE
NIGHT SEVERE WEATHER/WIND EPISODE OF JAN. 8-9, 2008...ONLY OFFSET BY
ABOUT 12H. IN THAT EPISODE...SURFACE TEMPERATURES IN THE 60S AND
DEWPOINTS OF 45-50F PRECEEDED THE APPROACHING FRONT.
THERE ARE STILL DISCREPANCIES AMONGST LATEST GUIDANCE IN TERMS OF
INSTABILITY AND QPF ASSOCIATED WITH FROPA ACROSS THE REGION. IT DOES
APPEAR POSSIBLE THAT A NARROW CORRIDOR OF WARMER SURFACE
TEMPERATURES /AROUND 60F/ AND MUCAPE OF 100-300 J PER KG MAY DEVELOP
IMMEDIATELY AHEAD OF THE FRONT ACROSS NY/PA. IF THIS CAN OCCUR AS
INDICATED IN LATEST NAM-WRF...NEAR SURFACE-BASED LOW-TOP CONVECTION
ASSOCIATED WITH THE SQUALL LINE COULD PRODUCE DAMAGING WINDS GIVEN
RAPID EWD MOTION AND INTENSE SHEAR.
OVERALL PROBABILITY OF ORGANIZED SEVERE STORMS REMAINS RELATIVELY
LOW AT THIS TIME BASED ON THE ARRAY OF DIFFERENT MODEL INSTABILITY
AND QPF FORECASTS. HOWEVER...IF QPF CONSENSUS AND STRONGER
INSTABILITY FORECASTS SHOW UP IN LATER MODEL GUIDANCE ACROSS THESE
AREAS...A SLGT RISK AREA MAY BE NEEDED FOR PARTS OF OH/PA/NY IN
SUBSEQUENT OUTLOOKS.
...SOUTHEAST/FL...
WEAK TO MODEST SURFACE-BASED INSTABILITY /MUCAPE 500-1000 J PER KG/
IS FORECAST TO DEVELOP FROM THE PIEDMONT ACROSS THE COASTAL PLAINS
OF NC/SC AND SOUTH TO FL THROUGH THE DAY. THIS WILL OCCUR WELL AHEAD
OF THE COLD FRONT WHERE SYNOPTIC SCALE LIFT AND EFFECTIVE BULK SHEAR
ARE EXPECTED TO BE WEAK/MARGINAL ON THE SRN FRINGE OF THE POTENT
SHORT WAVE TROUGH MOVING INTO CANADA. WHILE AN ISOLATED DIURNAL
STORM OR TWO COULD BRIEFLY ACHIEVE SEVERE LEVELS IN TERMS OF
HAIL/WIND...SITUATION DOES NOT APPEAR TO WARRANT HIGHER SEVERE
PROBABILITIES AT THIS TIME.
COLD FRONT WILL EVENTUALLY MOVE INTO PARTS OF THE REGION LATE WITH
SOME STRONGER CONVECTION POSSIBLE ALONG THIS FEATURE. TIME OF DAY
AND LACK OF STRONGER FORCING ON THE FRONT PRECLUDES WIDESPREAD
ORGANIZED SEVERE STORM POTENTIAL.
..CARBIN.. 03/31/2008
It'll be good to know BEFORE I spent a couple of hours organizing everything, though. We have some folks (me included!) who have a hard time driving at night when it's raining.
