SWODY1
SPC AC 040052
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0752 PM CDT SUN AUG 03 2008
VALID 040100Z - 041200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF THE NRN AND
CNTRL HIGH PLAINS INTO THE UPPER MIDWEST...
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE LOWER MS
VALLEY INTO ERN TX...
...ERN TX INTO LOWER MS VALLEY...
CLUSTERS OF TSTMS ARE ONGOING AS OF 00Z OVER NWRN MS/E-CNTRL AND
SERN AR AND ERN TX WITH ACTIVITY MOVING/PROPAGATING WWD/SWWD INTO A
HOT AND MODERATELY UNSTABLE BOUNDARY LAYER WITH MLCAPES OF 1500-2500
J/KG. RUC OBJECTIVE FIELDS AND AREA PROFILERS/VWPS INDICATE THAT A
BELT OF 20-35 KT ENELY MIDLEVEL FLOW EXISTS ACROSS THE REGION ON SRN
PERIPHERY OF HIGH CENTERED OVER THE OZARK PLATEAU. GIVEN THE
MODESTLY STRONG DEEP-LAYER...UNIDIRECTIONAL WIND PROFILES AND
MODERATELY UNSTABLE AIR MASS...ENVIRONMENT WILL REMAIN SUPPORTIVE OF
DOWNSHEAR COLD POOL ELONGATION/FORWARD STORM PROPAGATION WITH A
CONTINUED THREAT OF DAMAGING WINDS AND PERHAPS SOME HAIL.
...UPPER MIDWEST...
LATEST MESOANALYSIS INDICATES SURFACE LOW PRESSURE OVER FAR NERN NEB
WITH ATTENDANT WARM FRONT ARCING NEWD INTO S-CNTRL MN AND THEN SSEWD
THROUGH ERN IA INTO FAR WRN IL. A WEAK FRONT OR INVERTED TROUGH WAS
SLOWLY PUSHING EWD THROUGH WRN MN. ALOFT...A WELL-DEFINED SHORT
WAVE TROUGH FROM ERN ND ACROSS NRN MN WILL CONTINUE EWD INTO THE
UPPER GREAT LAKES TONIGHT.
A BAND OF ELEVATED TSTMS HAS PERSISTED TODAY ACROSS MN AND WI ALONG
NOSE OF 20-30 KT SWLY LLJ WHICH HAS BEEN MAINTAINED IN ADVANCE OF
MIGRATORY SHORT WAVE TROUGH. THUS FAR...ANY SURFACE-BASED TSTM
DEVELOPMENT HAS BEEN INHIBITED BY A WELL-DEFINED EML/CAP OBSERVED ON
00Z MPX SOUNDING. OF INTEREST...OVERLAYING 00Z OAX AND MPX
SOUNDINGS SUGGESTS THAT SIMILAR BOUNDARY LAYER CONDITIONS OVER ERN
NEB WOULD BE CLOSE TO ERODING CAP ALONG WARM FRONT OVER SRN MN.
HOWEVER...A PERSISTENT BAND OF MIDLEVEL CLOUDS HAS KEPT TEMPERATURES
NOTABLY COOLER. THEREFORE...THERE IS SOME QUESTION AS TO WHETHER
SURFACE-BASED STORM INITIATION WILL OCCUR.
LATEST SHORT TERM MODEL GUIDANCE REMAINS CONSISTENT IN SUGGESTING
THAT TSTMS WILL BECOME INCREASINGLY LIKELY NEAR OR N OF WARM FRONT
BETWEEN 04/00-03Z AS NOCTURNAL LLJ INTENSIFIES. CURRENT THINKING IS
THAT ANY STORMS THAT DEVELOP WILL BE SLIGHTLY ELEVATED WITH THE
POTENTIAL FOR SUPERCELLS CAPABLE OF MAINLY VERY LARGE HAIL AND
ISOLATED DAMAGING WINDS. HOWEVER...A TORNADO THREAT WILL EXIST WITH
ANY SURFACE-BASED SUPERCELL THAT CAN FORM NEAR THE BAROCLINIC ZONE
WHERE BUOYANCY AND LOW-LEVEL SHEAR WILL BE ENHANCED.
...NRN HIGH PLAINS...
WATER VAPOR IMAGERY SHOWS NEXT UPSTREAM IMPULSE MOVING THROUGH THE
NRN INTERMOUNTAIN REGION...WITH THIS FEATURE CONTINUING EWD ACROSS
MT OVERNIGHT. 00Z TFX/GGW SOUNDINGS INDICATE THAT VERTICAL SHEAR
REMAINS RELATIVELY STRONG WITH LOW-LEVEL ELY WINDS BENEATH 40-50 KT
WLY FLOW IN THE MIDLEVELS. WHILE BOUNDARY LAYER MOISTURE REMAINS
SOMEWHAT MARGINAL...LAPSE RATES ARE STEEP WHICH IS LARGELY
CONTRIBUTING TO POCKETS OF WEAK CONVECTIVE INSTABILITY. MODEL
GUIDANCE SUGGESTS THE POTENTIAL FOR ANOTHER MCS TO DEVELOP TONIGHT
OVER NRN WY OR SRN MT AS THE FORCING FOR ASCENT ASSOCIATED WITH
SHORT WAVE TROUGH ACTS ON THE STEEP LAPSE RATE ENVIRONMENT. SHOULD
THIS SCENARIO UNFOLD...THE POTENTIAL WILL EXIST FOR DAMAGING WINDS
AND HAIL WITH EVOLVING MCS. ACTIVITY WOULD THEN SPREAD EWD INTO THE
WRN DAKOTAS BY MONDAY MORNING.
...CNTRL HIGH PLAINS...
A LOW-AMPLITUDE IMPULSE TRANSLATING NEWD THROUGH SERN WY/N-CNTRL CO
APPEARS TO BE CONTRIBUTING TO AN INCREASE IN STORM COVERAGE OVER THE
NEB PNHDL AND NERN CO THIS EVENING. THIS ACTIVITY IS DEVELOPING TO
THE N OF A SURFACE FRONT WHICH EXTENDS FROM NERN NEB INTO E-CNTRL
CO. 00Z LBF SOUNDING EXHIBITED STEEP LAPSE RATES AND MODEST
BOUNDARY LAYER MOISTURE WHICH WERE CONTRIBUTING TO MLCAPES OF AROUND
1500 J/KG. GIVEN THE PRESENCE OF THE MIDLEVEL IMPULSE...MODEST
VERTICAL SHEAR AND MODERATE AMOUNTS OF POSITIVE AND NEGATIVE
BUOYANCY...THE POTENTIAL WILL EXIST FOR MCS EVOLUTION OVER WRN NEB
WITH THE PRIMARY SEVERE THREATS BEING DAMAGING WINDS AND HAIL.
FOR ADDITIONAL NEAR TERM GUIDANCE...PLEASE SEE MCD 2018.
...AZ...
SCATTERED TSTMS HAVE DEVELOPED ALONG THE MOGOLLON RIM AND ADJACENT
LOWER ELEVATIONS SW OF TUS WITHIN A STEEP LAPSE RATE ENVIRONMENT
WITH SBCAPES OF 300-500 J/KG. 00Z TUS SOUNDING SHOWED THAT WIND
FIELDS HAVE REMAINED RATHER LIGHT...THOUGH MODEL GUIDANCE DOES
SUGGEST SOME INCREASE IN ELY MIDLEVEL WINDS TONIGHT. AS
SUCH...ENVIRONMENT WILL REMAIN SUPPORTIVE OF ISOLATED DAMAGING WIND
GUSTS...ESPECIALLY IF STORM MERGERS CAN ORGANIZE A COLD POOL.
FOR ADDITIONAL NEAR TERM GUIDANCE...PLEASE SEE MCD 2017.
..MEAD.. 08/04/2008
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