SWODY2
SPC AC 230544
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1244 AM CDT FRI MAY 23 2008
VALID 241200Z - 251200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NRN AND CNTRL
PLAINS...
...SYNOPSIS...
NRN EXTENSION OF AMPLIFIED RIDGE FROM THE MS RIVER VALLEY NWD INTO
CNTRL CANADA WILL BREAK DOWN DURING THE DAY TWO PERIOD AS STRONG
SHORT WAVE TROUGH LIFTS NEWD FROM THE CNTRL HIGH PLAINS THROUGH THE
UPPER MS VALLEY. ELSEWHERE...SHORT WAVE TROUGH INITIALLY FROM THE
MID ATLANTIC COAST WWD INTO THE CNTRL APPALACHIANS WILL TRANSLATE
SEWD TO OFF THE SERN ATLANTIC COAST BY SATURDAY NIGHT.
IN THE LOW LEVELS...LEE CYCLONE OVER NERN WY/SE MT WILL SLOWLY
DEVELOP NWD THROUGH THE PERIOD WITH ATTENDANT WARM FRONT LIFTING NWD
THROUGH THE CNTRL INTO NRN PLAINS. THE SERN EXTENSION OF THIS
BAROCLINIC ZONE WILL ASSUME MORE OF A QUASI-STATIONARY
CHARACTER...STRETCHING SEWD THROUGH SWRN MO INTO THE LOWER MS
VALLEY. A DRYLINE WILL SLOWLY MIX EWD THROUGH THE DAY...LIKELY
EXTENDING FROM INTERSECTION WITH WARM FRONT OVER CNTRL NEB SWD
THROUGH CNTRL KS...WRN OR CNTRL OK INTO NWRN TX. IN THE SE...A WEAK
COLD FRONT WILL PUSH SEWD THROUGH SC AND GA INTO FL.
...NRN/CNTRL PLAINS...
LLJ AXIS INITIALLY FROM THE CNTRL PLAINS INTO NRN HIGH PLAINS WILL
SLOWLY PIVOT EWD ACROSS THE NRN PLAINS AND EVENTUALLY INTO THE UPPER
GREAT LAKES IN RESPONSE TO THE NEWD TRANSLATION OF ABOVEMENTIONED
SHORT WAVE TROUGH. THIS WILL SERVE TO ENHANCE THE NWD TRANSPORT OF
A VERY MOIST BOUNDARY LAYER THROUGH THE CNTRL PLAINS INTO MID MO
VALLEY...ALONG AND S OF RETREATING WARM FRONT. THIS MOISTURE IN
CONJUCTION WITH A STEEP LAPSE RATE PLUME ATTENDANT TO SHORT WAVE
TROUGH WILL CONTRIBUTE TO A MODERATE TO STRONGLY UNSTABLE AIR MASS
BY AFTERNOON WITH MLCAPES RANGING FROM 1000-1500 J/KG NEAR
INTERSECTION OF WARM FRONT AND DRYLINE/LEE TROUGH OVER CNTRL
NEB...TO AS HIGH AS 2500-3500 J/KG OVER ERN KS. THIS SURFACE-BASED
INSTABILITY AXIS /MLCAPES AOB 500-1000 J PER KG/ WILL EXTEND NWWD
ALONG WARM OR OCCLUDING FRONT THROUGH S-CNTRL INTO WRN SD AND SERN
MT.
TSTMS /LIKELY ELEVATED/ ARE EXPECTED TO BE ONGOING SATURDAY MORNING
ALONG LLJ AXIS FROM PORTIONS OF KS/NEB INTO THE DAKOTAS. THIS
ELEVATED TSTM ACTIVITY IS EXPECTED TO SPREAD EWD ACROSS THE DAKOTAS
INTO THE UPPER MS VALLEY AND EVENTUALLY UPPER GREAT LAKES SATURDAY
INTO SATURDAY NIGHT. THE PRESENCE OF STEEP MIDLEVEL LAPSE RATES AND
RESULTANT MUCAPES OF 1000-1500 J/KG WILL SUPPORT LARGE HAIL IN THE
MOST INTENSE STORMS.
ADDITIONAL SURFACE-BASED TSTMS ARE EXPECTED TO DEVELOP BY AFTERNOON
ALONG WARM OR OCCLUDED FRONT OVER WRN SD INTO ERN MT. WHILE SEVERE
HAIL WILL BE THE PRIMARY SEVERE WEATHER THREAT GIVEN THE STEEP LAPSE
RATES AND COOL THERMODYNAMIC PROFILES...A COUPLE TORNADOES WILL BE
POSSIBLE OWING TO THE BACKED SURFACE WINDS AND STRONG AMBIENT
LOW-LEVEL VORTICITY RESIDING ALONG BAROCLINIC ZONE.
POTENTIALLY MORE SIGNIFICANT TSTMS ARE EXPECTED TO DEVELOP BY
AFTERNOON ALONG THE WARM FRONT AND/OR DRYLINE OVER CNTRL/ERN NEB SWD
INTO N-CNTRL/NERN KS. HERE...MODERATE TO STRONG INSTABILITY WILL BE
COLOCATED WITH STRONG LOW AND DEEP-LAYER SHEAR WITH THE POTENTIAL
FOR INTENSE SUPERCELLS CAPABLE OF VERY LARGE HAIL...DAMAGING WINDS
AND TORNADOES. THE GREATER CONCENTRATION OF STORMS WILL LIKELY
RESIDE N OF THE KS/NEB BORDER ALONG THE SRN FRINGE OF HEIGHT FALLS
ATTENDANT TO UPPER TROUGH...WITH MORE ISOLATED TSTM DEVELOPMENT TO
THE S.
...SRN PLAINS...
A VERY MOIST BOUNDARY LAYER /DEWPOINTS IN THE 60S TO LOWER 70S/ WILL
EXIST BENEATH MIDLEVEL LAPSE RATES...CONTRIBUTING TO MODERATE TO
STRONG INSTABILITY /MLCAPES OF 2000-4000 J PER KG/ E OF DRYLINE.
LATEST MODEL GUIDANCE SUGGESTS THAT WEAK HEIGHT RISES WILL SPREAD
EWD OUT OF THE SRN HIGH PLAINS IN WAKE OF SHORT WAVE TROUGH LIFTING
NEWD INTO THE UPPER MS VALLEY. THUS...THERE IS SOME UNCERTAINTY AS
TO WHETHER ANY DIURNAL TSTM DEVELOPMENT WILL OCCUR. SHOULD AN
ISOLATED STORM DEVELOP AND BECOME SUSTAINED...THE POTENTIAL WILL
EXIST FOR DAMAGING WINDS AND HAIL GIVEN THE DEGREE OF INSTABILITY.
...OZARK PLATEAU INTO LOWER MS VALLEY...
REGION WILL RESIDE ALONG ERN EDGE OF STEEPER MIDLEVEL LAPSE RATE
PLUME BUT WITHIN A VERY MOIST LOW-LEVEL AIR MASS ALONG
QUASI-STATIONARY BOUNDARY WITH DEWPOINTS IN THE 60S TO LOWER/MID
70S...CONTRIBUTING TO MODERATE TO STRONG INSTABILITY. LARGE-SCALE
FORCING FOR ASCENT WILL REMAIN NEGLIGIBLE GIVEN PROXIMITY OF UPPER
RIDGE AXIS...HOWEVER THE PRESENCE OF THE LOW-LEVEL BAROCLINIC ZONE
SHOULD FOCUS DIURNAL STORM DEVELOPMENT WITH A THREAT OF LOCALLY
DAMAGING WINDS AND PERHAPS SOME HAIL.
...SERN GA INTO ERN FL...
HERE TOO...A VERY MOIST LOW-LEVEL AIR MASS WILL EXIST AHEAD OF
SWD-MOVING FRONT WITH DEWPOINTS IN THE 60S TO LOWER 70S. WHILE
MIDLEVEL LAPSE RATES WILL BE WEAKER THAN POINTS TO THE W...THIS
MOISTURE WILL LARGELY CONTRIBUTE TO POCKETS OF MODERATE INSTABILITY
WITH MLCAPES APPROACHING 1000-1500 J/KG. THIS INSTABILITY IN
CONJUNCTION WITH AROUND 30 KT OF DEEP LAYER FLOW MAY BE SUFFICIENT
TO SUPPORT A FEW ORGANIZED TSTMS ALONG THE FRONT WITH A THREAT OF
MAINLY STRONG WIND GUSTS. THIS THREAT MAY EXTEND SWD ACROSS THE ERN
FL PENINSULA IN ASSOCIATION WITH SCATTERED...DIURNAL STORMS
DEVELOPING ALONG THE SEA BREEZE BOUNDARY.
..MEAD.. 05/23/2008
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