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Click here to view the Day 1 Probabilistic Outlook for tornadoes, large hail,
and damaging wind gusts at 1227 UTC.
SPC AC 151227
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0727 AM CDT SAT MAR 15 2008
VALID 151300Z - 161200Z
...THERE IS A MDT RISK OF SVR TSTMS FROM EXTREME EASTERN
ALABAMA...ACROSS MUCH OF NORTHERN AND CENTRAL GEORGIA...INTO
WESTERN...CENTRAL...AND PARTS OF NORTHERN SOUTH CAROLINA...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE TN VALLEY EAST TO NC
AND SOUTH TO ERN SC AND SOME OF SRN GA...
...SYNOPSIS...
A LOW AMPLITUDE SHORT WAVE TROUGH ACCOMPANIED BY 500MB WINDS OF UP
TO 90KT WILL CONTINUE TO SPREAD RAPIDLY EAST OVER THE TN VALLEY AND
SOUTHEAST U.S. TODAY. SURFACE LOW PRESSURE HAS DEVELOPED IN RESPONSE
TO THE MID/UPPER LEVEL WAVE AND WAS LOCATED OVER THE LOWER MS VALLEY
THIS MORNING. A WARM FRONT EXTENDS EAST FROM THE SURFACE LOW TO A
WEAK QUASI-STATIONARY PIEDMONT FRONT FROM NRN GEORGIA INTO THE
CAROLINAS.
THE SURFACE LOW IS FORECAST TO TRACK/DEVELOP ENEWD ACROSS THE TN
VALLEY TO A POSITION NEAR THE SOUTHERN APPALACHIANS THROUGH LATE
TODAY. THE WARM SECTOR ASSOCIATED WITH THIS LOW WILL CONTINUE TO
OVERSPREAD THE TN VALLEY AND SOUTHEAST DURING THE DAY IN THE WAKE OF
STRONG STORMS THIS MORNING. A SMALLER-SCALE/SECONDARY LOW MAY TAKE
FORM ALONG THE PIEDMONT FRONT AMIDST WARM MOIST AND INCREASINGLY
UNSTABLE AIR MASS. STRONG DEEP-LAYER SHEAR AND ORGANIZING INFLUENCE
OF THIS LOW PRESSURE AREA COULD RESULT IN A ZONE OF ENHANCED TORNADO
POTENTIAL FROM PARTS OF ERN AL ACROSS GA AND INTO SC LATER THIS
AFTERNOON AND EARLY EVENING.
...TN VALLEY/SOUTHEAST...
LONG-LIVED BOWING STORM COMPLEX NOW APPEARS TO BE OUTRUNNING
STRONGER INSTABILITY AND DYNAMIC SUPPORT EARLY THIS MORNING ACROSS
NWRN SC. THIS MESOSCALE COMPLEX DEVELOPED LAST NIGHT IN RESPONSE TO
STRENGTHENING WARM ADVECTION AHEAD OF THE PLAINS SURFACE CYCLONE AND
APPEARS TO HAVE BEEN SUPPORTED OVERNIGHT BY FAVORABLE JUXTAPOSITION
OF LOW LEVEL JET AND WARM/QUASI-STATIONARY BOUNDARY BISECTING AL/GA.
WHILE THE CONVECTION CONTINUES TO SHOW SOME STRUCTURE...THE
INCREASINGLY STABLE DOWNSTREAM ENVIRONMENT EAST OF THE GA/SC BORDER
SHOULD LIMIT SEVERE POTENTIAL WITH THE DECAYING COMPLEX EARLY.
BUT...THE RESIDUAL/OUTFLOW EFFECTS OF THIS SYSTEM COULD PLAY A ROLE
IN ENHANCING TORNADO POTENTIAL LATER TODAY.
STRONGER THUNDERSTORMS ROOTED ABOVE THE BOUNDARY LAYER ON ELEVATED
FRONTAL SURFACE CONTINUE TO MOVE QUICKLY EAST ACROSS NRN AL ATTM.
STRONG DYNAMIC ASCENT WITHIN/BENEATH LEFT EXIT REGION OF MID LEVEL
JET STREAK SHOULD SUPPORT THIS ACTIVITY CONTINUING EAST FROM NRN AL
INTO NRN GA THROUGH THE MORNING. A THREAT FOR HAIL AND/OR ISOLATED
DAMAGING WINDS MAY ACCOMPANY THIS ACTIVITY AS IT MOVES EAST.
WARM/MOIST ADVECTION IS STRENGTHENING FROM THE LOWER MS VALLEY TO
THE TN VALLEY...AND 40-50KT LOW LEVEL JET WILL SPREAD EAST FROM MS
TO GA. SURFACE DEWPOINTS IN THE MIDDLE 60S F... STEEPENING LAPSE
RATES AND STRONG DYNAMIC ASCENT ACROSS THE REGION SHOULD PROMOTE
ADDITIONAL TSTM DEVELOPMENT COINCIDENT WITH DIURNAL DESTABILIZATION
AND MLCAPE VALUES CLIMBING TO AT LEAST 1500 J/KG.
DISCRETE STORMS MAY DEVELOP OR CONTINUE INTENSIFYING WITHIN THE LOW
LEVEL CONFLUENT FLOW ACROSS WARM SECTOR THROUGH THE DAY. THIS
ACTIVITY WILL ENCOUNTER SUFFICIENT LOW LEVEL AND DEEP-LAYER BULK
SHEAR TO BECOME SUPERCELLULAR. FORECAST WIND PROFILES FROM ERN AL TO
SERN TN...NRN GA...AND SC ALL SHOW PRONOUNCED LOW LEVEL HODOGRAPH
CURVATURE WITH EFFECTIVE SRH ON THE ORDER OF 200-400 M2/S2. THESE
VALUES COULD BE LOCALLY GREATER NEAR PIEDMONT FRONT...POSSIBLE
SECONDARY LOW...AND ANY RESIDUAL OUTFLOW BOUNDARIES IN THE WAKE OF
THE MORNING STORMS.
TSTMS IN THIS ENVIRONMENT WILL BE CAPABLE OF GENERATING STRONG
TORNADOES AND VERY LARGE HAIL. SOME CELLS MAY REMAIN ANCHORED ALONG
PIEDMONT BOUNDARY AND COULD TRACK FOR SOME DISTANCE ACROSS PARTS OF
GA/SC...AND PERHAPS EVEN INTO NC THROUGH THE EVENING. AN MCS COULD
EVOLVE FROM INITIALLY DISCRETE CONVECTION DUE TO ORGANIZING
INFLUENCE OF INTENSIFYING SYNOPTIC SCALE LOW EXPECTED TO DEVELOP
ACROSS ERN NC THROUGH LATE EVENING. WIND FIELDS AND FORCING WITH
THIS DEVELOPMENT WOULD FURTHER SUPPORT TORNADO POTENTIAL INTO THE
NIGHT ACROSS PARTS OF ERN/SERN NC. HOWEVER... UNCERTAINTIES
REGARDING RESIDUAL EFFECTS OF DECAYING MORNING MCS AND AIR MASS
QUALITY/RECOVERY ACROSS ERN NC PRECLUDE INCREASING THE TORNADO
PROBABILITIES TO SUPPORT A MDT RISK AT THIS TIME. DEPENDING ON
MESOSCALE EVOLUTION LATER TODAY...THE MDT RISK AREA MAY NEED TO BE
EXPANDED INTO NC.
ADDITIONAL SEVERE STORMS...PRIMARILY CAPABLE OF DAMAGING WINDS AND
HAIL COULD ACCOMPANY THE PRIMARY SYNOPTIC LOW PRESSURE SYSTEM AS IT
MOVES FROM TN ACROSS THE APPALACHIANS THROUGH THIS AFTERNOON.
..CARBIN/GRAMS.. 03/15/2008
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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