SWODY3
SPC AC 150707
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0207 AM CDT WED AUG 15 2007
VALID 171200Z - 181200Z
..THERE IS A SLGT RISK OF SVR TSTMS OVER THE MID
ATLANTIC/CAROLINAS...
..SYNOPSIS...
MODESTLY AMPLIFIED AND PROGRESSIVE FLOW ACROSS THE NRN HALF OF THE
CONUS IS FORECAST INTO THE WEEKEND. WHILE CENTER OF UPPER RIDGE IS
FORECAST TO PERSIST ACROSS THE CNTRL/SRN U.S...THE RIDGE MAY BEGIN
TO WEAKEN AND GRADUALLY SHRINK IN AREAL COVERAGE WITH TIME. THIS
PROCESS UNFOLDS AS IMPULSES EMANATE OUT OF PACIFIC NORTHWEST MEAN
TROUGH AND DAMPEN THE UPPER RIDGE AXIS ACROSS THE ROCKIES/NRN PLAINS
THROUGH THE PERIOD. MEANWHILE...SRN PERIPHERY OF THE RIDGE MAY BE
ERODED/WEAKENED AS DECAYING TROPICAL WAVE TRANSLATES WWD/NWWD OVER
TX.
DEEP TROUGH PRODUCING STRONG HEIGHT FALLS WILL MOVE ACROSS NEW
ENGLAND THROUGH SATURDAY AS REFRESHING CONTINENTAL POLAR AIR MASS
SPREADS SEWD OUT OF CANADA AND ACROSS THE GREAT LAKES AND NORTHEAST.
COLD FRONT MARKING THE LEADING EDGE OF THIS AIR MASS SHOULD SETTLE
SOUTH FROM THE MID ATLANTIC AND INTO THE CAROLINAS DURING THE
PERIOD. LATEST SREF MEAN PROGS INDICATE THIS FRONT WILL BE SITUATED
FROM SC WNWWD ACROSS THE LOWER MS VALLEY...AND THEN NWWD TO THE MO
VALLEY TO SD BY SATURDAY MORNING.
..MID ATLANTIC/CAROLINAS...
LIFT ALONG THE ADVANCING COLD FRONT....AND WITHIN DEVELOPING
THERMAL/LEE TROUGH...WILL PROVE SUFFICIENT FOR SCATTERED TSTMS FROM
DELMARVA SWD ACROSS THE CAROLINAS. GIVEN POTENTIAL FOR STRONG
DIURNAL DESTABILIZATION ACROSS THESE AREAS...AND INCREASINGLY STRONG
DEEP-LAYER WIND FIELDS...EXPECT PRIMARILY ORGANIZED MULTICELL
CONVECTION WITH A FEW TO SEVERAL DAMAGING WIND/HAIL EVENTS POSSIBLE.
..ROCKIES TO NRN PLAINS...
POTENTIAL FOR TSTMS SHOULD INCREASE FROM THE ROCKIES EWD ACROSS THE
PLAINS AS WEAK HEIGHT FALLS/ASCENT SPREAD EWD/NEWD OUT OF
LARGER-SCALE TROUGH DEVELOPING INLAND ACROSS THE PACIFIC NORTHWEST.
HEATING ACROSS THE HIGHER TERRAIN WILL AID IN OVERCOMING STRONG
CAP/INHIBITION ACROSS THESE REGIONS WITH ISOLATED HAIL/WIND
POSSIBLE. FARTHER EAST...ACROSS THE NRN HIGH PLAINS/DAKOTAS/MO
VALLEY...STORM INITIATION WILL BE TIED TO EITHER 1) EWD PROPAGATION
AND UPSCALE EVOLUTION OF CONVECTION COMING OFF THE HIGH TERRAIN...OR
2) DEVELOPMENT ALONG/NORTH OF FRONTAL ZONE BEING SUSTAINED BY
NOCTURNAL LLJ....OR A COMBINATION OF 1 AND 2. GIVEN STRENGTH OF THE
CAP ANTICIPATED ACROSS THESE AREAS NEAR/BENEATH STRONG UPPER RIDGE
AXIS...AND ONLY WEAK FORCING FROM LOW-AMPLITUDE AND POORLY RESOLVED
SHORT WAVE FEATURES...ONLY A LOW SEVERE PROBABILITY WILL BE FORECAST
AT THIS TIME. STRONG SHEAR WILL LIKELY EXIST ACROSS THE FRONTAL ZONE
AND IT IS QUITE POSSIBLE THAT LATER FORECASTS DEPICTING THE FRONTAL
LOCATION AND EDGE OF THE CAP WITH GREATER ACCURACY WILL ALLOW FOR
THE ADDITION OF HIGHER SEVERE STORM PROBABILITIES OVER THE NRN
PLAINS AREA.
..TX...
EVENTUAL TRACK OF TROPICAL LOW IS HIGHLY UNCERTAIN WITH A NUMBER OF
POTENTIAL OUTCOMES DEPICTED IN LATEST GUIDANCE. MOST MODELS DO
INDICATE A SIGNIFICANT INCREASE IN MOISTURE AND LOW LEVEL SLY FLOW
ACROSS THE SRN PLAINS THROUGH DAY 3. GIVEN THE POTENTIAL FOR A
DECAYING TROPICAL CYCLONE OVER TX...AND A CONSISTENT SIGNAL OF
RELATIVELY STRONG LOW LEVEL FLOW/SHEAR IN A NUMBER OF MODELS...A LOW
PROBABILITY SEVERE WEATHER AREA SEEMS WARRANTED OVER THE CENTER OF
TX FOR FRIDAY INTO EARLY SATURDAY.
.CARBIN.. 08/15/2007
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