ACUS02 KWNS 010551
SWODY2
SPC AC 010550
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1250 AM CDT SUN JUN 01 2008
VALID 021200Z - 031200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS OF THE CNTRL PLAINS
INTO THE MID MS AND LOWER OH VALLEYS...
...SYNOPSIS...
A PROGRESSIVE LARGE-SCALE PATTERN WILL CONTINUE THROUGH THE DAY TWO
PERIOD WITH THE MOST SIGNIFICANT HEIGHT FALLS OCCURRING OVER THE
N-CNTRL STATES. MORE SPECIFICALLY...A LEAD SHORT WAVE TROUGH /OR
PERHAPS SEVERAL SMALLER PERTURBATIONS/ WILL TRANSLATE EWD FROM THE
NRN HIGH PLAINS INTO UPPER GREAT LAKES BY TUESDAY MORNING. A MORE
SIGNIFICANT UPSTREAM LOW OVER THE PACIFIC NW WILL SLOWLY OPEN WHILE
MOVING EWD INTO THE NRN HIGH PLAINS.
IN THE LOW LEVELS...SURFACE PATTERN WILL REMAIN SOMEWHAT COMPLEX.
QUASI-STATIONARY BOUNDARY INITIALLY FROM LEE LOW OVER THE SRN HIGH
PLAINS EWD ACROSS OK AND THEN SEWD INTO THE LOWER MS VALLEY WILL
LIFT NEWD THROUGH THE PERIOD INTO THE MID MS VALLEY. WHILE PRIMARY
SURFACE LOW WILL GENERALLY DEVELOP NEWD INTO N-CNTRL OK...A
WEAKER...SECONDARY LOW WILL DEVELOP THROUGH ERN KS INTO NRN OR CNTRL
MO. MEANWHILE...ANOTHER WEAK SURFACE WAVE MAY DEVELOP EWD ALONG A
NRN QUASI-STATIONARY BOUNDARY ACROSS THE DAKOTAS WITH A TRAILING
COLD FRONT PUSHING SEWD FROM THE NRN HIGH PLAINS.
...CNTRL LOW PLAINS INTO THE MID MS/OH VALLEYS...
LOW-LEVEL MASS RESPONSE TO LEAD SHORT WAVE TROUGH MOVING ACROSS THE
NRN PLAINS WILL MAINTAIN A LLJ THROUGH THE PERIOD INITIALLY ACROSS
THE SRN/CNTRL PLAINS...WITH THIS FEATURE VEERING AND INTENSIFYING
OVER THE MID MS AND OH VALLEYS MONDAY NIGHT. THIS WILL ENHANCE THE
NWD/NEWD FLUX OF AN INCREASINGLY MOIST AIR MASS CURRENTLY RESIDING
ACROSS THE SRN PLAINS. THIS INCREASING MOISTURE COUPLED WITH STEEP
MIDLEVEL LAPSE RATE PLUME SPREADING EWD ACROSS THE CNTRL/SRN PLAINS
INTO MID/LOWER MS VALLEYS WILL CONTRIBUTE TO A MODERATE TO STRONGLY
UNSTABLE AIR MASS /MLCAPES OF 2000-3500 J PER KG/ MONDAY AFTERNOON
ALONG RETREATING WARM FRONT.
CLUSTERS OF ELEVATED TSTMS ARE EXPECTED TO BE ONGOING MONDAY MORNING
N OF SURFACE WARM FRONT FROM PORTIONS OF KS/NEB PERHAPS INTO
MO...DRIVEN LARGELY BY WARM THERMAL AND MOISTURE ADVECTIONS
OCCURRING ALONG NOSE OF LLJ. ELEVATED TSTMS SHOULD CONTINUE THROUGH
THE DAY WITHIN EXPANDING WAA REGIME WITH ACTIVITY SPREADING NEWD/EWD
EVENTUALLY INTO THE OH VALLEY MONDAY NIGHT. THE MOST INTENSE STORMS
WILL BE CAPABLE OF SEVERE HAIL GIVEN THE STEEP LAPSE RATES AND
MODERATELY STRONG CLOUD-BEARING SHEAR.
A POTENTIALLY MORE SIGNIFICANT SEVERE WEATHER THREAT MAY DEVELOP
MONDAY AFTERNOON INTO EVENING ALONG WARM FRONT LIFTING NEWD THROUGH
THE CNTRL LOW PLAINS AND OZARK PLATEAU. UNCERTAINTIES STILL EXIST
IN DIURNAL STORM INITIATION/EVOLUTION ALONG FRONT GIVEN: 1) THE
TENDENCY FOR A STRENGTHENING CAP FROM THE W...AND 2) THAT THE
STRONGER LARGE-SCALE FORCING FOR ASCENT WILL BE QUICKLY SHIFTING
EWD/NEWD OF THE REGION.
STILL IT DOES APPEAR THAT ISOLATED TO SCATTERED SURFACE-BASED STORM
DEVELOPMENT IS POSSIBLE WITHIN A THERMODYNAMIC AND KINEMATIC
ENVIRONMENT QUITE FAVORABLE FOR SUPERCELLS CAPABLE OF VERY LARGE
HAIL...DAMAGING WINDS AND TORNADOES. AN UPGRADE TO MODERATE RISK
MAY BECOME NECESSARY IN LATER OUTLOOKS ONCE FINER-SCALE DETAILS
BECOME MORE CERTAIN.
...NRN/CNTRL HIGH PLAINS INTO NRN PLAINS...
CONCERNS ABOUT THE DEGREE OF AIR MASS DESTABILIZATION PRECLUDE
HIGHER SEVERE PROBABILITIES AND A CATEGORICAL SLIGHT RISK INVOF OF
LEAD IMPULSE AND SURFACE FRONTAL SYSTEM OVER THE DAKOTAS...AND IN
ADVANCE OF PRIMARY UPPER LOW OVER THE NRN PLAINS. NONETHELESS...THE
PRESENCE OF STEEP MIDLEVEL LAPSE RATES AND MODEST VERTICAL SHEAR
SUGGEST A THREAT OF ISOLATED SEVERE STORMS CAPABLE OF SOME HAIL AND
LOCALLY STRONG WIND GUSTS.
ISOLATED SEVERE STORMS WILL ALSO BE POSSIBLE ALONG FRONT MOVING SWD
THROUGH THE CNTRL HIGH PLAINS OR WITHIN POST-FRONTAL UPSLOPE REGIME
MONDAY AFTERNOON AND EVENING.
...CNTRL/ERN GULF STATES...
A MOIST AND MODERATELY UNSTABLE AIR MASS WILL EXIST MONDAY AHEAD OF
SYNOPTIC FRONT AND ANY RESIDUAL OUTFLOW BOUNDARIES. LARGE-SCALE
FORCING FOR ASCENT IS FORECAST TO REMAIN RATHER WEAK AS MIDLEVEL
TROUGH SHIFTS EWD INTO THE WRN ATLANTIC. HOWEVER...SUSTAINED
CONVERGENCE ALONG THE PRE-EXISTING BOUNDARIES SHOULD FOSTER
SCATTERED DIURNAL STORMS...A FEW OF WHICH COULD CONTAIN SOME HAIL
AND STRONG WIND GUSTS GIVEN THE MODERATE INSTABILITY AND MODEST
VERTICAL SHEAR.
..MEAD.. 06/01/2008
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