SPC AC 062001
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0301 PM CDT THU AUG 06 2009
VALID 062000Z - 071200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE GREAT BASIN/NRN
INTERMOUNTAIN REGION ACROSS THE ROCKIES AND INTO THE NRN/CENTRAL
PLAINS...
...THERE IS A SLGT RISK OF SVR TSTMS OVER WRN LA INTO E/SE TX...
...THERE IS A SLGT RISK OF SVR TSTMS OVER ERN NC AND VA TIDEWATER...
...CENTRAL PLAINS TO THE OZARKS...
OBJECTIVE ANALYSES INDICATED A MORE STABLE BOUNDARY LAYER IS NOW IN
PLACE ACROSS PARTS OF CENTRAL KS IN THE WAKE OF THE MORNING TSTM
ACTIVITY. THIS COMBINED WITH MID LEVEL WARMING EXPECTED INTO
CENTRAL KS/NEB THROUGH TONIGHT/EARLY FRIDAY SHOULD TEND TO INHIBIT
NEW CONVECTIVE DEVELOPMENT ACROSS PARTS OF CENTRAL KS. THUS...THIS
OUTLOOK HAS REDUCED SEVERE WEATHER PROBABILITIES OVER KS.
FARTHER SE...A MODERATELY UNSTABLE AIR MASS HAS DEVELOPED FROM SERN
KS/SRN MO INTO FAR ERN OK AND MUCH OF AR. GIVEN THIS DEGREE OF
INSTABILITY DOWNSTREAM OF MCV LEFT OVER FROM MORNING KS TSTM
ACTIVITY...NOW APPROACHING SERN KS...MAY PROVE SUFFICIENT IN NEW
TSTM DEVELOPMENT. HOWEVER...WEAK DEEP LAYER SHEAR SUGGESTS THE
OVERALL SEVERE WEATHER THREAT SHOULD REMAIN LOW. OTHER THAN
EXTENDING LOW SEVERE PROBABILITIES EWD ACROSS SOUTH CENTRAL MO AND
NRN/CENTRAL AR...A SLIGHT RISK IS NOT NEEDED.
...PARTS OF E/SE TX AND WRN LA...
THIS OUTLOOK HAS REMOVED THE ERN EXTENT OF THE SLIGHT RISK AREA IN
ERN LA...AS THIS REGION IS IN THE WAKE OF THE ONGOING TSTM CLUSTER
TRACKING WWD THIS AFTERNOON THROUGH WRN LA. ISOLATED STORMS HAVE
DEVELOPED OVER SERN LA WHERE THE AIR MASS IS MODERATELY UNSTABLE...
BUT LACK OF STRONGER FORCING FOR ASCENT ALOFT SHOULD TEND TO LIMIT
THE TSTM COVERAGE AND OVERALL SEVERE WEATHER THREAT.
ELSEWHERE...CONVECTIVE/SEVERE WEATHER THREATS ARE ON TRACK PER THE
1630Z OUTLOOK. FOR ASSOCIATED MESOSCALE/SEVERE WEATHER DETAILS
PLEASE REFER TO RESPECTIVE WATCHES AND MESOSCALE DISCUSSIONS.
..PETERS.. 08/06/2009
.PREV DISCUSSION... /ISSUED 1131 AM CDT THU AUG 06 2009/
...LA/EAST CENTRAL/SERN TX...
BAND OF STRONG/SEVERE THUNDERSTORMS OVER NERN LA HAS SHOWN SIGNS OF
WEAKENING DURING THE LAST HOUR AS STORM CORES DECREASE IN INTENSITY
AND IR CLOUD TOPS EXHIBIT WARMING. THIS ACTIVITY MAY PRODUCE
LOCALIZED BRIEF STRONG WIND GUSTS OVER THE NEXT HOUR OR TWO AS IT
SPREADS SWWD. THE ENVIRONMENT AHEAD OF THE OUTFLOW IS VERY MOIST
AND UNSTABLE WITH SURFACE DEW POINTS IN THE MID/UPPER 70S AND MLCAPE
TO 3000 J/KG. CONTINUED DIABATIC HEATING WILL CONTRIBUTE TO
ADDITIONAL DESTABILIZATION THIS AFTERNOON. VAD AND WIND PROFILER
DATA SHOW STRONGER NORTHERLY WINDS ABOVE 6-7 KM WITH 50+ KT FLOW
ABOVE 300 MB...PROVIDING STRONG DEEP LAYER SHEAR THAT WILL ENHANCE
STORM ORGANIZATION AND INTENSITY. THERE IS POTENTIAL FOR NEW
UPDRAFTS TO DEVELOP ALONG THE LEADING EDGE OF THE OUTFLOW...AND THE
SWWD PROPAGATION OF STORMS WILL INCREASE GIVEN THE GRADUAL
DEVELOPMENT AND CONSOLIDATION OF A STRONGER COLD POOL. A SLIGHT
RISK HAS BEEN ADDED TO THIS REGION FOR THE THREAT OF PRIMARILY
DAMAGING WIND GUSTS THIS AFTERNOON AND EVENING.
...ERN NC/VA TIDEWATER REGION...
THE ENVIRONMENT OVER ERN NC IS DESTABILIZING AS SURFACE TEMPERATURES
WARM INTO THE MID 80S...WITH MLCAPE OF 1500-2000 J/KG ACROSS THE
REGION. LATEST VAD WINDS FROM AKQ SHOW 30 KT SWLY FLOW ABOVE 3 KM
AGL...SUGGESTING THAT STRONGER WINDS ALOFT ARE ALONG THE NWRN EDGE
OF THE LOW LEVEL MOISTURE/INSTABILITY AXIS. THUNDERSTORMS ARE
STARTING TO DEVELOP OVER NERN NC AND ADDITIONAL DEVELOPMENT IS
LIKELY ACROSS MORE OF ERN NC THIS AFTERNOON AS THE UPPER TROUGH
APPROACHES FROM THR WEST AND THE WEAK CAP CONTINUES TO WEAKEN. A
FEW SEVERE STORMS WILL BE POSSIBLE THIS AFTERNOON WITH PRIMARY
THREAT FOR WET MICROBURSTS AND ISOLATED HAIL.
...NRN GREAT BASIN INTO NRN INTERMOUNTAIN REGION AND NRN ROCKIES...
VIGOROUS UPPER LOW OVER NRN CA IS MOVING NEWD TOWARD THE NRN GREAT
BASIN AND NRN INTERMOUNTAIN REGION...ACCOMPANIED BY A STRONG SWLY
MID/UPPER LEVEL JET ON THE ERN PERIPHERY OF THE LOW. STRONG DYNAMIC
FORCING FOR LARGE SCALE ASCENT IS ALREADY UNDERWAY WITHIN THE LEFT
EXIT OF THE JET ALOFT...WITH ISOLATED STRONG/SEVERE STORMS OVER NRN
NV INTO SWRN ID. VISIBLE IMAGERY INDICATES CLEAR SKIES FROM NERN NV
INTO SOUTH CENTRAL/SERN ID AND SWRN MT IMMEDIATELY TO THE EAST OF
THE CURRENT CONVECTION...WITH STRONG DIABATIC HEATING AND
DESTABILIZATION LIKELY TO OCCUR IN THIS REGION DURING THE AFTERNOON.
ADDITIONAL THUNDERSTORMS ARE EXPECTED TO DEVELOP THROUGH THE
AFTERNOON AND EVENING IN ADVANCE OF THE PROGRESSIVE UPPER LOW...AND
STRONG DEEP LAYER SHEAR ASSOCIATED WITH THE JET ALOFT WILL INCREASE
THE THREAT FOR SEVERE STORMS INCLUDING A FEW SUPERCELLS AS WELL AS
BOWING LINE SEGMENTS. DRY ADIABATIC LOW LEVEL LAPSE RATES WILL
ENHANCE POTENTIAL FOR DAMAGING WIND GUSTS...WITH AN ADDITIONAL
THREAT FOR LARGE HAIL WITH STRONGER CELLS.
...NRN/CENTRAL PLAINS...
ONGOING ELEVATED STORMS OVER SD ARE LIKELY TO CONTINUE SLOWLY EWD
THIS AFTERNOON WITH ISOLATED CELLS CAPABLE OF MARGINALLY SEVERE
HAIL. A GREATER SEVERE THREAT IS LIKELY TO DEVELOP LATE THIS
AFTERNOON AND EVENING OVER THE HIGH PLAINS FROM SERN MT INTO NERN
CO/SWRN NEB WHERE STRONGER HEATING AND DESTABILIZATION IS EXPECTED
WITHIN AREAS OF MORE LIMITED CLOUD COVER. MODERATELY STRONG
WESTERLY FLOW ALOFT AND VEERING WIND PROFILES WITH HEIGHT WILL
PROVIDE SUFFICIENT VERTICAL SHEAR TO ENHANCE SEVERE STORM THREAT
INCLUDING POTENTIAL FOR SUPERCELL DEVELOPMENT. ACTIVITY IS LIKELY
TO SPREAD EWD ACROSS THE PLAINS DURING THE OVERNIGHT HOURS AS THE
LOW LEVEL JET STRENGTHENS AFTER DARK...WITH A CONTINUING THREAT FOR
LARGE HAIL AND STRONG/SEVERE WIND GUSTS.
...PARTS OF NM...
WELL-DEFINED VORTICITY MAX IS EVIDENT IN SATELLITE IMAGERY MOVING
NEWD OVER SWRN NM. THIS FEATURE IS EXPECTED TO MOVE SLOWLY ACROSS
CENTRAL TOWARD ERN NM THIS AFTERNOON INTO TONIGHT AND ENHANCE
THUNDERSTORMS DEVELOPMENT ALONG/AHEAD OF ITS TRACK. ISOLATED SEVERE
STORMS WILL BE POSSIBLE.
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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