[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 131631
SWODY1
SPC AC 131629

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CDT THU APR 13 2006

VALID 131630Z - 141200Z

...THERE IS A SLGT RISK OF SVR TSTMS PARTS OF THE MID AND UPPER MS
VALLEY...

...SYNOPSIS...
BROAD RIDGING ACROSS MUCH OF CONUS WITH FAST WESTERLIES EXTENDING
EWD ACROSS NRN US INTO WRN GREAT LAKES. FLOW THEN BECOMES WNWLY INTO
TROUGH OFF E COAST.

MID LEVEL TROUGH ERN GREAT LAKES WILL MOVE ESEWD TO BE OFFSHORE BY
THIS EVENING. UPSTREAM...S/WV TROUGH AND MIDLEVEL WIND MAX CURRENTLY
NRN PLAINS/CANADIAN BORDER REGION MOVES ACROSS FLAT RIDGE TO WRN
GREAT LAKES TONIGHT.

CURRENTLY ACTIVE PRESSURE FALLS UPPER MS VALLEY WILL LEAD TO SURFACE
LOW DEVELOPMENT ACROSS SRN MN THIS AFTERNOON. WARM FRONTAL ZONE WILL
EXTEND FROM SURFACE LOW ESEWD ACROSS WI INTO SRN LWR MI BY THIS
EVENING WITH A DRY LINE FROM THE LOW SSWWD THRU ERN NEB INTO CENTRAL
KS.

SLY LOW LEVEL FLOW IS SPREADING MOISTURE AND INSTABILITY NWD THRU
ERN PLAINS AND LOWER MO VALLEY IN ADVANCE OF THIS SYSTEM WITH AIR
MASS BECOMING VERY UNSTABLE BY MID AFTERNOON.

...SRN MN/IA ACROSS SRN WI/NRN IL INTO WRN OH...
LOW LEVEL MOISTURE SPREADING NEWD THRU ERN PLAINS AND LOWER MO
VALLEY COUPLED WITH STEEP LAPSE RATES IN PLACE AND NEARLY FULL
HEATING WILL RESULT IN MLCAPES IN EXCESS OF 3000 J/KG DEVELOPING IN
WARM SECTOR THIS AFTERNOON. OBSERVED MOISTURE ADVECTION SUPPORTS LOW
60 DEWPOINTS INTO IA THIS AFTERNOON...NOT QUITE AS HIGH AS THE
NAM...HOWEVER SUFFICIENT TO DEVELOP THE VERY UNSTABLE AIR MASS.  CAP
WILL HOLD MUCH OF AFTERNOON IN THE WARM SECTOR...HOWEVER WARM
FRONTAL LIFT COULD INITIATE STORMS ACROSS SRN MN INTO WI.  STRONG
VEERING SHEAR PROFILES AND AVAILABLE THERMODYNAMICS SUPPORT
SUPERCELL POTENTIAL...AND WITH SURFACE BASED STORMS...TORNADOES WILL
BE POSSIBLE.  IN ADDITION VERY LARGE HAIL IS QUITE LIKELY PER SPC
HAIL MODEL OUTPUT.

DRY LINE WILL ALSO BECOME AN INCREASING CONCERN FOR INITIATION BY
EVENING IA SWD INTO NRN MO. AGAIN VERY LARGE HAIL WOULD BE THE
PRIMARY THREAT WHILE STORM MODE REMAIN MORE CELLULAR.

OVERNIGHT THE CONTINUED AVAILABILITY OF MDT TO VERY UNSTABLE AIR
ALONG WITH THE INCREASE AND VEERING LOW LEVEL JET SHOULD FUEL THE
DEVELOPMENT OF ONE OR MORE SEVERE MCS'S.  INCREASING THREAT OF
DAMAGING WINDS ALONG WITH THE LARGE HAIL POTENTIAL WILL SPREAD EWD
OVERNIGHT INTO THE OH VALLEY AS THE UPPER WIND MAX/S/WV TROUGH MOVES
EWD INTO WRN LAKES.

...NY SWD TO VA...
STEEP LAPSE RATES AND STRONG HEATING COUPLED WITH ADEQUATE MOISTURE
AND COLD AIR ALOFT WILL SUPPORT SCATTERED THUNDERSTORMS THIS
AFTERNOON.  LARGE HAIL WOULD BE POSSIBLE WITH THE STRONGEST UPDRAFTS
GIVEN THE COLD AIR ALOFT AND STEEP LAPSE RATES.  WITH ACTIVITY NOT
EXPECTED TO BECOME VERY ORGANIZED AS LOW LEVEL SHEAR GENERALLY
WEAK...WILL CONTINUE A LOW SEVERE HAIL AND WIND RISK  THRU THE
AFTERNOON.

..HALES/JEWELL.. 04/13/2006