[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 172322
SWODY1
SPC AC 172320

DAY 1 CONVECTIVE OUTLOOK AMEND 1
NWS STORM PREDICTION CENTER NORMAN OK
0620 PM CDT MON JUL 17 2006

VALID 172000Z - 181200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE GREAT LAKES INTO THE
MIDDLE MS VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS OVER ERN TX INTO WRN/SRN LA...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE SWRN
DESERTS/LWR CO RVR VLY...

AMENDED FOR SLGT RISK ACROSS THE LAS VEGAS AREA

***AMENDED PORTION***
...LWR CO RVR VLY AND THE SWRN DESERTS...
STRONGEST TSTMS HAVE DEVELOPED ALONG THE HIGH COUNTRY ACROSS NWRN AZ
NWD INTO AREAS N-E OF KLAS.  THESE STORMS WILL PROPAGATE WWD TOWARD
THE LWR CO RVR VLY AREA...INCLUDING THE LAS VEGAS VLY LATER THIS
EVENING WITH RISKS OF DAMAGING WINDS AND PERHAPS HAIL.

FARTHER S...ACTIVITY HAS BEEN SUPPRESSED THIS AFTN.  BUT...AN MCV
CONTINUES TO MOVE WNWWD THROUGH PIMA COUNTY AND MAY BE THE IMPETUS
FOR INCREASING TSTMS LATER THIS EVENING.  THESE STORMS WILL ALSO
HAVE A RISK OF DAMAGING WINDS.

***REMAINDER UNCHANGED***

...GREAT LAKES/MIDDLE MS VALLEY...
WATER VAPOR IMAGERY SHOWS A STRONG SHORT WAVE TROUGH MOVING EWD
ACROSS ONTARIO/LAKE SUPERIOR...ACCOMPANIED BY A 50-60 KT MID LEVEL
JET STREAK OVER LAKE SUPERIOR AND NRN WI/UPR MI.  SURFACE COLD FRONT
IS CURRENTLY EXTENDING FROM ERN LAKE SUPERIOR ACROSS CENTRAL WI INTO
SWRN IA...AND THIS BOUNDARY IS EXPECTED TO REACH A ST LAWRENCE
VALLEY/CENTRAL INDIANA/CENTRAL MO LINE BY 18/12Z.  VERY MOIST AND
WARM AIR MASS IS LOCATED AHEAD OF THE FRONT WITH SURFACE
TEMPERATURES IN THE 90S AND DEW POINTS IN THE 70S.

12Z SOUNDINGS INDICATED ELEVATED MIXED LAYER/STEEP MID LEVEL LAPSE
RATES EXTENDED EWD INTO THE GREAT LAKES REGION...ENHANCING POTENTIAL
INSTABILITY /MLCAPE OF 3000-4000 J/KG/ BUT ALSO LIMITING CONVECTIVE
DEVELOPMENT IN THE WARM SECTOR AHEAD OF THE COLD FRONT.  SEVERAL
CLUSTERS OF STRONG/SEVERE THUNDERSTORMS HAVE FORMED FROM NRN LOWER
MI SWWD INTO EAST CENTRAL WI AND NERN IA...AND A WEAKENING CAP
IMMEDIATELY ALONG/AHEAD OF THE FRONT SHOULD PERMIT ADDITIONAL STORMS
TO DEVELOP THIS AFTERNOON AND EVENING. PRESENCE OF VERY UNSTABLE
ENVIRONMENT COUPLED WITH 30-40 KT DEEP LAYER VERTICAL SHEAR WILL
SUPPORT ADDITIONAL SEVERE STORMS TO DEVELOP THROUGH THE EVENING
HOURS...WITH STRONGEST UPDRAFTS CAPABLE OF PRODUCING VERY LARGE HAIL
AND DAMAGING WIND GUSTS.  STRONG/SEVERE CONVECTION MOVING FROM WI
INTO LOWER MI AND TOWARD THE LOWER GREAT LAKES IS EXPECTED TO
CONTINUE THROUGH THE OVERNIGHT HOURS AS STRONG DYNAMIC FORCING
ASSOCIATED WITH THE SHORT WAVE OVERSPREADS THE AREA FROM THE WEST
AND PROVIDES FAVORABLE FORCING FOR LARGE SCALE ASCENT.

A FEW SEVERE STORMS MAY ALSO DEVELOP SWWD ALONG THE FRONT INTO PARTS
OF CENTRAL/SWRN IA LATER THIS AFTERNOON WHERE VISIBLE IMAGERY SHOWS
CU FIELD BECOMING ENHANCED...WITH THIS ACTIVITY GRADUALLY SPREADING
SEWD INTO NRN MO.  THIS ACTIVITY IS LIKELY TO WEAKEN AFTER SUNSET.

...ARKLATEX INTO SRN LA...
WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL CYCLONIC CIRCULATION MOVING
SLOWLY SWD ACROSS SERN LA...WITH STRONG MID/UPPER LEVEL DRYING
SPREADING SWD ACROSS THE REGION.  THERMODYNAMIC PROFILES ARE
CHARACTERIZED BY INCREASING TEMPERATURE/DEW POINT SPREADS AS A LOW
LEVEL INVERTED-V SOUNDING STRUCTURE DEVELOPS IN THE LOWEST 1-2
KM...WITH THETA-E DECREASING RAPIDLY ABOVE THE VERY MOIST PBL. 20
KT NELY WINDS ALOFT WILL FAVOR SWWD PROPAGATION OF STORMS WITH
POTENTIAL FOR WET MICROBURSTS TO DEVELOP.  SEE MESOSCALE DISCUSSION
1537 FOR MORE DETAILS.

..JPR/WEISS.. 07/17/2006