[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 041622
SWODY1
SPC AC 041620

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1120 AM CDT THU MAY 04 2006

VALID 041630Z - 051200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF CENTRAL AND
SOUTHWESTERN TEXAS...

...THERE IS A SLGT RISK OF SVR TSTMS FROM SRN TX TO ERN NM...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE ARKLATEX EWD TO THE
SRN APPALACHIANS...

...SRN PLAINS...
UPPER LOW OVER NRN INTERMOUNTAIN REGION DRIFTS SWD TODAY AS S/WV
TROUGH AND MID LEVEL WIND MAX MOVE EWD ACROSS AZ INTO NM TONIGHT. 
GRADUAL INCREASE IN MID LEVEL FLOW SPREADS EWD INTO SRN HIGH PLAINS
WITH APPROACH OF UPPER IMPULSE RESULTING IN IMPROVEMENT OF DEEP
LAYER SHEAR THIS AREA IN SUPPORT OF SUPERCELL DEVELOPMENT.

OVERNIGHT CONVECTION HAS CLEARED OUT OF W TX WHICH IS ALLOWING
RETURN OF LOW LEVEL MOISTURE N/NWWD  THRU THE TRANS PECOS REGION. 
SURFACE FRONTAL BOUNDARY EXTENDS WWD JUST TO S OF RED RIVER VALLEY
INTO SERN CORNER OF NM AND WILL MOVE ONLY SLOWLY SWD THRU THE
AFTERNOON.

WITH STEEP LAPSE RATES ABOVE THE MOIST BOUNDARY LAYER PERSISTING
ACROSS ALL OF SRN PLAINS EWD TO LOWER MS VALLEY...THERMODYNAMICS
WILL BE MORE THAN SUFFICIENT BY MID/LATE AFTERNOON FOR SEVERE
THUNDERSTORM DEVELOPMENT.

WHILE THE LOW LEVEL SHEAR WILL GENERALLY BE ONLY MARGINAL...AROUND
10 KTS...30-40KT OF DEEP LAYER SHEAR IN CONCERT WITH MLCAPES BETWEEN
2000-3000 J/KG BY MID AFTERNOON EXPECTED TO FAVOR DEVELOPMENT OF
SUPERCELLS.

MOST LIKELY INITIATION WILL BE IN AREA OF LOW LEVEL CONVERGENCE
VICINITY OF FRONTAL ZONE AND THE  HIGHER TERRAIN OF ERN NM/SWRN TX
WHERE HEATING WILL BE VERY STRONG.

WILL CONTINUE THE MDT RISK...AS THE SHEAR AND EXPECTED UNSTABLE AIR
MASS WILL RESULT IN LARGE HAIL WITH ANY SUPERCELL THAT FORMS.  IN
ADDITION TORNADOS ARE MORE OF A THREAT IN SRN HI PLAINS THAN ON WED
WHEN DEEP LAYER SHEAR WAS NOT QUITE AS STRONG AND MOISTURE PROFILES
TOOK LONGER TO RECOVER FROM OVERNIGHT CONVECTION.

...MID MS VALLEY AND GULF COAST STATES...
OUTFLOW BOUNDARIES FROM OVERNIGHT STORMS STRETCH WWD FROM NRN AL/MS
INTO SRN AR.  WHILE LAPSE RATES AND SHEAR NOT QUITE AS FAVORABLE AS
OVER SRN PLAINS...THE AIR MASS IS MOIST AND WITH AFTERNOON HEATING
EXPECTED TO BECOME MODERATELY UNSTABLE. BY MID AFTERNOON WITH
SURFACE TEMPERATURES RISING THRU THE 80S...SURFACE BASED
THUNDERSTORMS SHOULD DEVELOP...MOST LIKELY IN CONVERGENCE VICINITY
OF THE OLD OUTFLOW BOUNDARIES.  STORM MODE SHOULD BE MULTI-CELL
WITH PRIMARY SEVERE THREAT OF MARGINALLY SEVERE HAIL AND LOCAL
DAMAGING DOWNBURSTS.

...INTERMOUNTAIN REGION...
BAND OF CONVERGENCE/BAROCLINIC ZONE ON E SIDE OF UPPER TROUGH
EXTENDS FROM SWRN WY TO CENTRAL NV.  STRONG HEATING AND EXISTING
STEEP LAPSE RATES ON S SIDE OF THIS ZONE WILL LEAD TO SCATTERED
THUNDERSTORMS BY MID AFTERNOON.  WHILE LOW LEVEL MOISTURE IS ON THE
LOW SIDE...SUFFICIENT CAPE...GIVEN THE VERY STEEP LAPSE RATES AND
30-40 KT OF DEEP LAYER SHEAR WILL SUPPORT A FEW STRONG
THUNDERSTORMS. MARGINALLY SEVERE HAIL AND BRIEF DAMAGING DOWNBURST
WINDS WILL BE THE LIMIT OF THE THREAT FROM MID-AFTERNOON THRU THE
EVENING.

...OH VLY TO THE LWR GRT LKS...
MOISTURE RETURN WILL BE SCANT AHEAD OF TRAILING COLD FRONT
ASSOCIATED WITH NRN STREAM IMPULSE IN ONTARIO. THIS WILL LIMIT 
CAPE TO AOB 500 J/KG.  BUT FRONTAL UPLIFT AND FORCING FOR ASCENT ON
SRN EDGE OF ONTARIO TROUGH MAY BE SUFFICIENT FOR SCATTERED AFTERNOON
TSTMS ACROSS NY/PA.  DEEPLY MIXED BOUNDARY LAYER WITH SIZABLE
TEMPERATURE/DEW POINT SPREADS COULD SUPPORT LOCALLY DAMAGING GUSTS. 


FARTHER SW ALONG THE FRONT...UVV SHOULD BE WEAKER.  BUT WIDELY
SCATTERED STORMS SHOULD DEVELOP SW INTO THE LWR OH VLY BY EARLY
EVENING...WHERE THERMODYNAMIC SETUP COULD SUPPORT A COUPLE CELLS
WITH MARGINALLY SEVERE HAIL.

..HALES/GUYER.. 05/04/2006