SWODY2
SPC AC 290552
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1252 AM CDT SUN APR 29 2007
VALID 301200Z - 011200Z
..THERE IS A SLGT RISK OF SVR TSTMS MONDAY AFTERNOON AND EARLY
MONDAY NIGHT ACROSS PARTS OF SRN MN...NRN IA AND SWRN WI....
..THERE IS A SLGT RISK OF SVR TSTMS MONDAY AFTERNOON AND EVENING
ACROSS S TX....
..SYNOPSIS...
MAIN BAND OF WESTERLIES WILL EXTEND ALONG THE NRN TIER OF STATES AS
MID/UPPER LEVEL TROUGH MOVES ACROSS NEW ENGLAND THEN OFFSHORE MONDAY
NIGHT. MID LEVEL SHORTWAVE TROUGH WILL TRACK ACROSS THE NRN PLAINS
INTO THE UPPER MIDWEST LATE MONDAY MORNING INTO TUESDAY MORNING.
LOOKS LIKE THE GFS HANDLES THIS FEATURE A BIT BETTER AND SLOWER THAN
THE NAM. MEANWHILE...MID/UPPER LEVEL LOW OVER CENTRAL MEXICO AT
THIS TIME WILL BE OVER THE SRN PLAINS BY THIS PERIOD.
..PARTS OF MN/IA/WI AND NWRN IL...
GFS TAKES SURFACE LOW ASSOCIATED WITH MID LEVEL SHORTWAVE FROM
CENTRAL SD INTO NWRN IA MONDAY AFTERNOON. A WARM FRONT IS FORECAST
TO EXTEND FROM THE LOW EWD ALONG THE MN/IA BORDER THEN SEWD THRU
CENTRAL OH. A COLD FRONT WILL TRAIL THE LOW THRU THE NEB PANHANDLE
INTO NWRN WY. THE NAM IS A BIT MORE CONSERVATIVE WITH SURFACE DEW
POINTS THAN THE GFS...AND GIVEN THE PRESENCE OF THE MID/UPPER LEVEL
LOW OVER THE S CENTRAL U.S. LOOKS A BIT MORE REALISTIC. LOW LEVEL
JET OF 30-40 KT IS FORECAST TO EXTEND FROM NERN KS INTO CENTRAL IA
AND SWRN WI BY 21-00Z ENHANCING LOW LEVEL WARM ADVECTION AND LIFT IN
THE VICINITY OF THE WARM FRONT. THIS WILL BE COUPLED WITH 30-50 KT
WNWLY MID LEVEL FLOW CREATING DEEP LAYER SHEAR OF 40-60 KT ACROSS
THE AREA. ANALYSIS OF NAM SOUNDINGS SHOW STRONG VERTICAL SHEAR
PROFILES ABOVE THE BOUNDARY LAYER ACROSS MN INTO CENTRAL WI...BUT
WEAKER PROFILES IN THE WARM SECTOR ACROSS CENTRAL IA.
AIR MASS ALONG AND SOUTH OF THE WARM FRONT BOUNDARY IS EXPECTED TO
BE MODERATELY UNSTABLE WITH BOTH MODELS PRODUCING MUCAPE OF
1000-2000 J/KG WITH LOW/MID LEVEL LAPSE RATES AROUND 8C/KM. NAM
FORECASTS T/TD VALUES OF 88/65 AROUND KALO AT 22Z WITH A MLCAPE JUST
UNDER 2800 J/KG AND INDICATING LARGE HAIL WITH THE PROFILE.
THUS...EXPECT SCATTERED STRONG/SEVERE THUNDERSTORMS TO DEVELOP JUST
AHEAD OF THE ADVANCING SHORTWAVE IN THE VICINITY OF THE WARM FRONT
JUST E OF THE LOW. LARGE HAIL AND DAMAGING WINDS LOOK TO BE THE
MAIN THREATS AT THIS TIME. BUT...GIVEN THE STRONG SHEAR PROFILES
AROUND NERN IA/SWRN WI...SOME ISOLATED TORNADOES COULD OCCUR.
..RIO GRANDE VALLEY AND S CENTRAL TX...
REMNANTS OF A DAY1 MCS SHOULD EFFECT MUCH OF THE ENVIRONMENT ACROSS
THIS REGION DURING THE PERIOD. BOTH MODELS STILL PROJECT A
MODERATELY UNSTABLE AIR MASS DURING THE AFTERNOON MOSTLY FROM
AVAILABLE HEATING. BOTH MODELS ARE GENERALLY IN THE 1000-1500 J/KG
RANGE FOR MUCAPE CORRESPONDING WITH DEEP LAYER SHEAR OF AROUND 40
KT. THUS...LOOK FOR REGENERATION OF WIDESPREAD THUNDERSTORMS ACROSS
THE SOUTHERN PLAINS WITH A FEW STRONG/SEVERE THUNDERSTORMS WITH HAIL
AND DAMAGING WINDS ACROSS PARTS OF S CENTRAL TX.
.MCCARTHY.. 04/29/2007
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