[SWODY1] SWODY1

[SWODY1 at goshenarc.org]

ACUS01 KWNS 100553
SWODY1
SPC AC 100551

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1251 AM CDT SAT JUL 10 2004

VALID 101200Z - 111200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 40 NE
HVR 30 WSW GGW 40 W MLS 25 SE 3HT HLN 10 NW 3DU 35 SSW FCA 55 NW
CTB.

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM CDR 10
N RAP 10 N REJ 10 SSW DIK DVL GFK FAR 55 W AXN SPW 40 SSW FOD 15 NNE
FNB 45 SSW HSI MCK IML AIA CDR.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 E PSM 35 ENE ALB
25 SSW ART ...CONT... 80 W CAR 20 NE CAR.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 65 WSW TUS 40 ESE PHX
35 NNE PHX 55 SSE IGM 15 SSW IGM IGM 20 S PGA 15 NNE U17 25 N U28 15
SE EVW 30 NNW OGD 50 S TWF 15 W TWF 20 SE BOI 45 WNW BOI 60 S BNO 30
NNE 4LW 65 NNW 4LW 55 ESE RDM 55 SSW PDT 10 WSW PDT 10 S PUW 45 ENE
GEG 35 WSW 63S 20 W YKM 15 SSW HQM ...CONT... 35 N CMX IWD 55 NE EAU
20 W VOK 20 S MSN 20 SE MKE 35 NNE MKG 50 NNE MTC ...CONT... 45 WSW
ERI 20 N PSB 10 S ACY ...CONT... 15 NW DRT 45 NNE JCT 35 WNW SEP 40
NNE ABI 30 ENE BGS 25 SE INK 30 SW P07.

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE
NORTHERN/CENTRAL PLAINS....

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS WESTERN/CENTRAL
MONTANA....

STRONGER WESTERLIES WILL REMAIN GENERALLY CONFINED TO THE CANADIAN/
U.S. BORDER REGION THROUGH THIS FORECAST PERIOD.  THIS FLOW REGIME
WILL REMAIN BROADLY ANTICYCLONIC ON NORTHERN PERIPHERY OF
SUBTROPICAL RIDGE...DOWNSTREAM OF VIGOROUS SHORT WAVE TROUGH PROGGED
TO LIFT FROM THE PACIFIC NORTHWEST COAST INTO THE NORTHERN
ROCKIES...UPSTREAM OF PERSISTENT TROUGH ACROSS NORTHERN NEW ENGLAND
AND THE NORTHERN ATLANTIC COAST.

...NORTHERN PLAINS...
CONSIDERABLE UNCERTAINTY EXISTS WITH REGARD TO FORECAST EVOLUTION OF
CONVECTIVE ACTIVITY TODAY...WITH LOW PROBABILITY SEVERE THREAT
OUTLOOKED OVER FAIRLY BROAD AREA OF THE NORTHERN/CENTRAL PLAINS.  AT
THE PRESENT TIME...HIGHEST PROBABILITIES OF THUNDERSTORM DEVELOPMENT
AND ATTENDANT SEVERE THREAT APPEAR TO EXIST ACROSS SOUTH DAKOTA...
AND MAY BEGIN AS EARLY AS MID DAY NEAR THE SOUTH DAKOTA/NORTH DAKOTA
BORDER.

SHORT WAVE TROUGH EMBEDDED WITHIN SUBTROPICAL WESTERLIES IS READILY
EVIDENT IN WATER VAPOR LOOPS MIGRATING INTO THE NORTH CENTRAL
ROCKIES.  THIS FEATURE IS FORECAST TO PROGRESS EAST OF THE ROCKIES
EARLY IN THE DAY...AS UPSTREAM SHORT WAVE TROUGH BEGINS TO LIFT OUT
OF THE PACIFIC NORTHWEST COAST.  WHILE MOIST BOUNDARY LAYER WILL
LIKELY STILL BE CAPPED AT MIDDAY...INCREASING LOWER/MID TROPOSPHERIC
WARM ADVECTION ABOVE CAPPING INVERSION IS EXPECTED TO SUPPORT
CONVECTIVE INITIATION BY 18Z.  BEST CHANCE FOR THIS APPEARS TO BE
WEST/NORTHWEST OF THE MOBRIDGE SD AREA...WITH MODELS SUGGESTING
FORCING SUFFICIENT FOR CLUSTER OF STORMS SPREADING EASTWARD ACROSS
SOUTHERN NORTH DAKOTA/NORTHERN SOUTH DAKOTA.  

EMBEDDED WITHIN STEEP MID-LEVEL LAPSE RATE ENVIRONMENT...LARGE HAIL
WILL BE POSSIBLE WITH INITIAL DEVELOPMENT...BUT TENDENCY SHOULD BE
FOR THIS THREAT TO DIMINISH AS ACTIVITY DEVELOPS EASTWARD.  STEEPER
LOW/MID-LEVEL LAPSE RATES WILL REMAIN CONFINED TO THE WESTERN
PLAINS...WHERE POTENTIAL FOR STRONGEST NEW CONVECTIVE DEVELOPMENT
APPEARS TO EXIST.  FOCUSED LOW-LEVEL CONVERGENCE/WARM ADVECTION ON
NOSE OF SOUTHERLY LOW-LEVEL JET...EAST OF SURFACE LOW OVER CENTRAL
SOUTH DAKOTA...IS EXPECTED TO PROVIDE FORCING FOR ACTIVITY...WHICH
SHOULD OCCUR NEAR/SHORTLY AFTER PEAK HEATING IN THE 21-23Z TIME
FRAME. 

WITH SURFACE DEW POINTS NEAR 70F...POINT FORECAST SOUNDINGS SUGGEST
MEAN MIXED LAYER CAPE IN EXCESS OF 3000 J/KG...SUPPORTIVE OF INTENSE
UPDRAFTS.  THOUGH FLOW WILL GENERALLY BE WEAK TO MODERATE IN
STRENGTH...VEERING WITH HEIGHT IN LOWER TO MID-LEVELS WILL
CONTRIBUTE TO SUFFICIENT SHEAR FOR SUPERCELLS...BEFORE LARGER
CONVECTIVE CLUSTER EVOLVES/SPREADS EASTWARD BY EARLY EVENING. 
THERMODYNAMIC ENVIRONMENT WILL BE SUPPORTIVE OF DOWNBURSTS...AND
EVENTUAL EVOLUTION OF STRONG COLD POOL WITH BROADER SCALE DAMAGING
WIND THREAT ACROSS CENTRAL/EASTERN SOUTH DAKOTA.  

STRENGTHENING/ VEERING LOW-LEVEL JET DURING THE LATE EVENING HOURS
WILL ALLOW ACTIVITY TO SPREAD INTO PARTS OF THE UPPER MISSISSIPPI
VALLEY... BUT POTENTIAL FOR DESTABILIZATION APPEARS WEAKER THIS
AREA...LIKELY LIMITING SEVERE THREAT.

...MONTANA...
THOUGH BOUNDARY LAYER DEW POINTS WILL REMAIN RELATIVELY MARGINAL FOR
VIGOROUS CONVECTIVE DEVELOPMENT...MOIST UPSLOPE FLOW REGIME WILL
DEVELOP INTO SURFACE LOW DEVELOPING IN THE LEE OF THE MONTANA
ROCKIES.  THIS WILL OCCUR WITH APPROACH OF STRONG SHORT WAVE TROUGH
LATE THIS AFTERNOON AND EVENING...AND FORCING WILL BE SUFFICIENT FOR
CONVECTIVE DEVELOPMENT.  DEEP MIXED BOUNDARY LAYER WITH CAPE
EXCEEDING 1000 J/KG IS EXPECTED BY 11/00Z...LIKELY SUPPORTING
EVOLUTION OF AT LEAST SMALL ORGANIZED CONVECTIVE CLUSTER.  MID/UPPER
FLOW IS NOT PROGGED TO BE PARTICULARLY STRONG...BUT LOW-LEVEL
EASTERLIES VEERING TO MODERATE MID-LEVEL WESTERLIES WILL CONTRIBUTE
TO STRONG VERTICAL SHEAR.

WHILE ISOLATED LARGE HAIL IS POSSIBLE...PRIMARY SEVERE THREAT
APPEARS TO BE DAMAGING DOWNBURST AND EVOLUTION OF SMALL VIGOROUS
COLD POOL ACCOMPANIED BY POTENTIALLY DAMAGING WINDS ALONG GUST FRONT
ACROSS WESTERN/CENTRAL MONTANA.  SEVERE THREAT IS EXPECTED TO
DIMINISH AFTER 11/06Z...IN MORE STABLE/STABILIZING BOUNDARY LAYER
ACROSS EASTERN MONTANA.

...OHIO VALLEY...
LINGERING LOW-LEVEL CONFLUENT ZONE/OUTFLOW BOUNDARIES ARE EXPECTED
TO BECOME FOCUS FOR THUNDERSTORM ACTIVITY TODAY.  MID-LEVEL CAPPING
APPEARS LIKELY TO BE RELATIVELY WEAK...AND ACTIVITY MAY BECOME
FAIRLY WIDESPREAD BY EARLY AFTERNOON.  THIS WILL LIMIT OVERALL
SURFACE HEATING...BUT MEAN MIXED LAYER CAPE IN EXCESS OF 2000 J/KG
IS POSSIBLE...SUPPORTIVE OF VIGOROUS UPDRAFTS WITH HEAVY
RAIN...PERHAPS SOME HAIL.  SOUTH OF WESTERLIES...SHEAR WILL REMAIN
QUITE WEAK...BUT ISOLATED DOWNBURSTS WILL BE POSSIBLE.

..KERR/JEWELL.. 07/10/2004

...NOTICE...
FOR USERS DECODING THE POINTS PARAGRAPH HEREIN...LATITUDE AND
LONGITUDE POINTS FOR THE CATEGORICAL AND PROBABILISTIC OUTLOOK
GRAPHICS ALSO ARE LOCATED IN A SEPARATE PRODUCT UNDER THE WMO
HEADINGS WUUS01 PTSDY1...WUUS02 PTSDY2...AND WUUS03 PTSDY3.  THE
INCLUSION OF POINTS IN THIS PRODUCT WILL EVENTUALLY BE DISCONTINUED.