ACUS1 KMKC 290103 SWODY1 MKC AC 290059 STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWBC. VALID 290100Z - 291200Z NO SVR TSTMS FCST. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 50 S VCT 20 NW NIR 40 S SAT 15 WNW SAT 35 N SAT 35 NW AUS 20 WSW TPL 40 ENE ACT 35 WNW TYR 40 N TYR 35 W TXK 20 NE TXK 45 NNW ELD 35 SW PBF 45 S PBF 40 SW GLH 40 ENE MLU 35 NNW HEZ 30 ENE ESF 25 S ESF 35 ENE LCH 35 SSE LCH. ...ERN AND SERN TX THROUGH LOWER MS VALLEY... COLD FRONT FROM THE UPPER MS VALLEY SWWD THROUGH NWRN TX CONTINUES MOVING SEWD. BOUNDARY LAYER MOISTURE WITH SURFACE DEWPOINTS AROUND 60 HAS RETURNED NWD AND IS CONTRIBUTING TO MARGINAL INSTABILITY IN WARM SECTOR ACROSS NERN TX. RICHER MOISTURE AND STEEPER MID LEVEL LAPSE RATES ARE CONTRIBUTING TO MODERATE INSTABILITY ACROSS S AND SERN TX WITH SBCAPES FROM 1500 TO 2000 J/KG. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ASSOCIATED WITH WEAK WARM ADVECTION ARE DEVELOPING OVER PORTIONS OF NERN TX INTO NRN LA AND SRN AR. FURTHER S...ATMOSPHERE STILL APPEARS CAPPED THOUGH 00Z CRP AND BRO SOUNDINGS SHOW CAP HAS WEAKENED SINCE 12Z. ADDITIONAL STORMS MIGHT DEVELOP THIS EVENING AND BUILD SWD ALONG FRONT TOWARD GREATER INSTABILITY AS FRONT INTERCEPTS MOIST AXIS. STRONGER FLOW ALOFT REMAINS FARTHER N ACROSS NRN TX INTO SRN AR WHERE INSTABILITY IS MORE MARGINAL. HOWEVER...CRP SOUNDING SHOWS STRONG VEERING THROUGH THE BOUNDARY LAYER CONTRIBUTING TO DEEP LAYER SHEAR AROUND 40 KT DESPITE RELATIVELY WEAK LOW TO MID LEVEL WINDS. IF STORMS CAN DEVELOP SWD TOWARD STRONGER INSTABILITY...DEEP LAYER SHEAR MAY BE SUFFICIENT TO SUPPORT MID LEVEL ROTATION WHICH WOULD ENHANCE POTENTIAL FOR AN ISOLATED STORM OR TWO TO PRODUCE LARGE HAIL. HOWEVER...THREAT FOR AN ORGANIZED SEVERE EVENT APPEARS TOO MARGINAL TO WARRANT A SLIGHT RISK. ..DIAL.. 11/29/00  ACUS3 KMKC 290106 SWOMCD MKC MCD 290106 MNZ000-NDZ000-290600- SPC MESOSCALE DISCUSSION 2028 FOR NORTHERN MN / EXTREME SOUTHEASTERN ND CONCERNING...HEAVY SNOW... HEAVY SNOW WITH RATES OF 1-2 IN/HR ARE POSSIBLE ACROSS PORTIONS OF NORTHERN MN THOROUGH 29/06Z. RADAR AND SATELLITE TRENDS INDICATE DEFORMATION AXIS BEGINNING TO DEVELOP ACROSS NORTHERN MN JUST NORTH OF SURFACE LOW WHICH WAS LOCATED 25 W AXN AT 29/00Z. MPX RAOB SHOWS NEARLY SATURATED PROFILE CONSISTENT WITH 28/18Z ETA MODEL FORECAST OF GREATER THAN 80% MEAN SFC-700 MB RH OVER NORTHERN MN. ETA ALSO INDICATES THAT ISOTACH GRADIENT WILL INCREASE OVER NORTHERN MN IN ENTRANCE REGION OF DEVELOPING JET STREAK OVER SOUTHERN ONTARIO RESULTING IN INCREASING UPPER LEVEL DIVERGENCE ACROSS THE AREA. THIS COUPLED WITH 850 MB CONVERGENCE NORTH OF THE SURFACE LOW SHOULD MAINTAIN STRONG VERTICAL MOTION IN A 60 MILE WIDE BAND FROM 20 S FAR TO 45 E BIJ FOR THE NEXT SEVERAL HOURS...RESULTING IN MODERATE TO HEAVY SNOW WITH RATES OF 1-2 IN/HR POSSIBLE. ALTHOUGH WATER VAPOR IMAGERY SUGGESTS SOME DRY AIR ADVECTING INTO SOUTHWESTERN MN AT 29/00Z...EAST-SOUTHEAST MOVEMENT OF UPPER TROUGH SHOULD KEEP NORTHERN MN IN NEARLY SATURATED THERMODYNAMIC PROFILE. SNOWFALL SHOULD DECREASE IN INTENSITY AFTER 29/06Z AS UPPER LEVEL SPEED MAX MOVES AWAY FROM THE AREA AND STRONGEST VERTICAL MOTION ASSOCIATED WITH UPPER LEVEL SHORT WAVE SHIFT EAST. ..JANISH.. 11/29/00 ...PLEASE SEE WWW.SPC.NOAA.GOV/ FOR GRAPHIC PRODUCT...  ACUS3 KMKC 290149 SWOMCD MKC MCD 290148 WIZ000-ILZ000-INZ000-290900- SPC MESOSCALE DISCUSSION 2029 FOR SOUTHEASTERN WI / NORTHEASTERN IL / NORTHWESTERN IN CONCERNING...FREEZING RAIN... RADAR AND SATELLITE TRENDS INDICATE WIDESPREAD PRECIPITATION DEVELOPING IN STRONG WARM ADVECTION ZONE OVER IA AND WESTERN IL AT 29/01Z. AS UPPER LEVEL SHORTWAVE TROUGH MOVES EAST-SOUTHEASTWARD ACROSS ALONG MN/IA BORDER...BAND OF PRECIPITATION IS EXPECTED TO MOVE INTO EASTERN WI/IL AND NORTHWESTERN IN. SURFACE WET BULB TEMPERATURES ARE BELOW FREEZING ACROSS MUCH OF NORTHEASTERN IL...SOUTHEASTERN WI...AND NORTHWESTERN IN AT THIS TIME AND ALTHOUGH TEMPERATURES ARE EXPECTED TO REMAIN NEARLY STEADY OVER THE NEXT FEW HOURS...PRECIPITATION IS EXPECTED TO FALL AS FREEZING RAIN WITH 3 HOUR ACCUMULATIONS UP TO 0.10 IN ACROSS THE AREA. SURFACE GROUND TEMPERATURES HAVE BEEN ABOVE TEMPERATURES DURING THE DAY...SO PRIMARY THREAT WILL BE TO ELEVATED SURFACES. ETA MODEL FORECAST SOUNDINGS AND PRECIPITATION TYPE ALGORITHMS SUPPORT THIS SCENARIO WITH FREEZING RAIN FORECAST THROUGH 29/09Z. PRECIPITATION WILL GRADUALLY CHANGE TO SNOW FROM NORTH TO SOUTH ACROSS THE AREA AFTER 29/09Z AS WARM ADVECTION DECREASES AND ADIABATIC COOLING LOWERS THE TEMPERATURE PROFILE BELOW 0 DEG C ABOVE THE SURFACE. ..JANISH.. 11/29/00 ...PLEASE SEE WWW.SPC.NOAA.GOV/ FOR GRAPHIC PRODUCT...  ACUS3 KMKC 290201 SWOMCD MKC MCD 290201 COR FOR WORDING WIZ000-ILZ000-INZ000-290900- SPC MESOSCALE DISCUSSION 2029 FOR SOUTHEASTERN WI / NORTHEASTERN IL / NORTHWESTERN IN CONCERNING...FREEZING RAIN... RADAR AND SATELLITE TRENDS INDICATE WIDESPREAD PRECIPITATION DEVELOPING IN STRONG WARM ADVECTION ZONE OVER IA AND WESTERN IL AT 29/01Z. AS UPPER LEVEL SHORTWAVE TROUGH MOVES EAST-SOUTHEASTWARD ALONG MN/IA BORDER...BAND OF PRECIPITATION IS EXPECTED TO MOVE INTO EASTERN WI/IL AND NORTHWESTERN IN. SURFACE WET BULB TEMPERATURES ARE BELOW FREEZING ACROSS MUCH OF NORTHEASTERN IL...SOUTHEASTERN WI...AND NORTHWESTERN IN AT THIS TIME AND SINCE TEMPERATURES ARE EXPECTED TO REMAIN NEARLY STEADY OVER THE NEXT FEW HOURS...PRECIPITATION IS EXPECTED TO FALL AS FREEZING RAIN WITH 3 HOUR ACCUMULATIONS UP TO 0.10 IN ACROSS THE AREA. SURFACE GROUND TEMPERATURES HAVE BEEN ABOVE FREEZING DURING THE DAY...SO PRIMARY THREAT WILL BE TO ELEVATED SURFACES. ETA MODEL FORECAST SOUNDINGS AND PRECIPITATION TYPE ALGORITHMS SUPPORT THIS SCENARIO WITH FREEZING RAIN FORECAST THROUGH 29/09Z. PRECIPITATION WILL GRADUALLY CHANGE TO SNOW FROM NORTH TO SOUTH ACROSS THE AREA AFTER 29/09Z AS WARM ADVECTION DECREASES AND ADIABATIC COOLING LOWERS THE TEMPERATURE PROFILE BELOW 0 DEG C ABOVE THE SURFACE. ..JANISH.. 11/29/00 ...PLEASE SEE WWW.SPC.NOAA.GOV/ FOR GRAPHIC PRODUCT...  ACUS1 KMKC 290556 SWODY1 MKC AC 290555 STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWBC. VALID 291200Z - 301200Z NO SVR TSTMS FCST. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 SSE SRQ 15 N MLB. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 50 N BRO 30 SW ALI 45 SE SAT 60 SSW TYR 10 N SHV 40 ENE MLU 35 N MCB 25 E BTR 45 SE 7R4. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 S AST 10 SSW EUG 40 N MFR 30 SW LMT 25 S SVE 30 WSW TVL 10 S SCK SFO. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 40 SE PSB 35 E HGR 25 W DCA 10 E CHO 25 NNW LYH 20 NE BLF 10 E 5I3 20 NNE JKL 50 ENE LEX 35 SE LUK 55 SW CMH 10 SSE CMH 25 N ZZV 25 SE CAK 35 S FKL 25 W PSB 40 SE PSB. ...UPPER OH VALLEY... STEEP LAPSE RATES WILL ACCOMPANY SHORTWAVE TROUGH THROUGH THE OH VALLEY WEDNESDAY. SOME BOUNDARY LAYER MOISTURE WILL SPREAD NEWD ALONG SWLY 850 MB JET AND MAY CONTRIBUTE TO MARGINAL INSTABILITY AS IT IS ADVECTED UNDERNEATH STEEP MID LEVEL LAPSE RATES. SHALLOW CONVECTION DEVELOPING ALONG SRN END OF COMMA HEAD MAY EVENTUALLY BECOME VIGOROUS ENOUGH TO PRODUCE ISOLATED LIGHTING STRIKES AS ATMOSPHERE DESTABILIZES DURING THE DAY. ...SERN TX THROUGH LOWER MS VALLEY... SHOWERS AND ISOLATED THUNDERSTORMS ASSOCIATED WITH WARM ADVECTION SHOULD BE ONGOING AT START OF THE PERIOD ACROSS PORTIONS OF ERN TX AND THE LOWER MS VALLEY. HOWEVER...THIS ACTIVITY SHOULD GRADUALLY DECREASE AS LOW LEVEL JET VEERS AND WEAKENS. OTHER ACTIVITY MAY DEVELOP ALONG FRONT ACROSS COASTAL TX AS ATMOSPHERE DESTABILIZES DURING THE DAY. ...SRN FL... EVENING SOUNDINGS SHOW SUBSTANTIAL CAPPING INVERSION BETWEEN 2 AND 3 KM AGL ACROSS MUCH OF S FL. LARGE SCALE ASCENT ACCOMPANYING SHORTWAVE TROUGH AND MOISTENING BOUNDARY LAYER SHOULD WEAKEN CAP. SUFFICIENT BOUNDARY LAYER MOISTURE SHOULD BE IN PLACE TO RESULT IN MARGINAL INSTABILITY ONCE CAP IS REMOVED...ESPECIALLY IN AREAS THAT CAN RECEIVE SOME DIABATIC HEATING. SEABREEZE BOUNDARIES MAY ENHANCE CONVECTIVE DEVELOPMENT AS ATMOSPHERE DESTABILIZES DURING THE AFTERNOON. ...NRN CA AND PACIFIC NW... ISOLATED THUNDERSTORMS ARE CURRENTLY OCCURING IN WARM CONVEYOR BELT APPROACHING THE COAST. STEEP LAPSE RATES ASSOCIATED WITH COLD AIR ALOFT N OF CYCLONICALLY CURVED JET WILL CONTRIBUTE TO MARGINAL INSTABILITY. OTHER MORE CELLULAR ACTIVITY MAY DEVELOP BEHIND WARM ADVECTION BAND BY AFTERNOON. ATMOSPHERE SHOULD UNDERGO FURTHER DESTABLIZATION DURING THE DAY AS DIABATIC HEATING OCCURS IN DRY SLOT OF SHORTWAVE TROUGH. MUCAPES COULD APPROACH 500 J/KG. STRONG FLOW ALOFT ASSOCIATED WITH MID LEVEL JET WILL CONTRIBUTE TO STRONG SHEAR PROFILES...ESPECIALLY OVER THE VALLEYS OF NRN CA WHERE LOW LEVEL FLOW MAY REMAIN BACKED. GIVEN POTENTIAL FOR UPDRAFT ROTATION...STEEP LAPSE RATES AND LOW WET BULB ZERO LEVELS...ISOLATED LOW TOPPED STORMS COULD PRODUCE MARGINAL HAIL DURING THE AFTERNOON. HOWEVER...DEGREE OF INSTABILITY IS NOT EXPECTED TO BE SUFFICIENT FOR AN ORGANIZED SEVERE THREAT. ..DIAL.. 11/29/00  ACUS2 KMKC 290831 SWODY2 MKC AC 290823 STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 2 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWI47 KWBC. VALID 301200Z - 011200Z NO TSTMS FCST. ...SYNOPSIS/FORECAST... THE FLOW WILL BECOME MORE ZONAL ACROSS THE LOWER 48 ON THURSDAY AS DEEP BUT PROGRESSIVE UPPER LOW CONTINUES E OFF THE MID ATLANTIC COAST. SOME AMPLIFICATION IS...HOWEVER...EXPECTED LATER IN THE PERIOD AS HEIGHTS RISE OVER THE WRN STATES IN ADVANCE OF NEXT STRONG SHORTWAVE ROUNDING BASE OF LONG-WAVE TROUGH POSITION OVER THE ERN GULF OF AK. A RESIDUAL AREA OF MOIST BOUNDARY LAYER AIR WILL LINGER ALONG THE TX GULF COAST AS FRONT APPROACHING REGION TODAY DISSIPATES JUST OFFSHORE. NEITHER SATELLITE NOR MODEL GUIDANCE...HOWEVER... INDICATE PRESENCE OF A SUFFICIENTLY STRONG SRN STREAM IMPULSE TO ACT ON THIS AIR MASS TO RESULT IN THUNDERSTORM DEVELOPMENT. ..CORFIDI.. 11/29/00  ACUS1 KMKC 291300 SWODY1 MKC AC 291258 STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWBC. VALID 291300Z - 301200Z NO SVR TSTMS FCST. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 N AOO HGR 15 NNE ROA 15 SE 5I3 LUK 10 WNW DAY 30 SW MFD 20 SE CAK 30 NE PIT 20 N AOO. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 40 E PSX 35 N PSX 40 S CLL 10 W LFK 45 SE SHV 35 SW MLU 25 NW HEZ 40 N LFT 20 SW 7R4. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 10 NW AST SLE 30 NNW MFR 35 SSW MFR 25 WSW MHS 35 NE RBL 50 SE RBL 45 S UKI. ...SYNOPSIS... VIGOROUS UPPER LOW NOW OVER THE UPPER MS VLY WILL RAPIDLY TRANSLATE EWD ACROSS THE MIDWEST TODAY AND TO THE MIDDLE ATLANTIC SEABOARD OVERNIGHT. MEANWHILE...STRONG VERTICALLY STACKED LOW NEAR 47N/139W IS EXPECTED TO MOVE EWD TO NEAR BC TONIGHT. NEGATIVELY TILTED TROUGH TRAILING THE UPPER LOW WILL MOVE NEWD INTO THE PACIFIC NW THIS MORNING AND INTO THE NRN GREAT BASIN/INTERMOUNTAIN WEST BY THU MORNING. AT THE SURFACE...A WEAK COLD FRONT WORKING SWD THROUGH LA AND ERN TX THIS MORNING...WILL REACH THE SRN LA AND THE TX GULF COAST BY LATE THIS AFTERNOON. OTHERWISE...A STRONG BAROCLINIC ZONE SITUATED ALONG THE OR AND NRN CA COASTS WILL MOVE INLAND INTO ERN PARTS OF WA...ORE AND NRN CA BY EVENING. ...PACIFIC NW AND NRN CA... LEADING EDGE OF COLDER AIR ALOFT IS BEGINNING TO MOVE INTO THE COASTAL AREAS OF OR AND NRN CA ATTM AS EVIDENT BY CELLULAR CUMULUS ON SATELLITE. CORE OF MINUS 26C MIDLEVEL TEMPERATURES IS EXPECTED TO MOVE ACROSS NRN CA AND THE PACIFIC NW LATER THIS MORNING. THUS...TSTMS ARE LIKELY TO DEVELOP...PRIMARILY ALONG COASTAL AREAS. HOWEVER...EXTRAPOLATING BACK EDGE OF FRONTAL BAND CLOUDINESS TO THE NRN SIERRA BY 18 UTC ARGUES THAT SOME INSOLATION WILL LIKELY OCCUR AS FAR EAST AS THE NRN SACRAMENTO VALLEY WHERE MUCAPES COULD APPROACH 500 J/KG. GIVEN FALLING WBZ LEVELS AND STRONG 6KM SHEAR NEAR 30 KTS...ISOLATED MARGINALLY SEVERE HAILSTONES ARE POSSIBLE WITHIN STRONGER STORMS. ...TX/LA GULF COASTAL AREA... COMBINATION OF GRADUALLY VEERING LOW LEVEL FLOW AND NEGATIVE VORTICITY ADVECTION OCCURING OVER THE REGION WILL TEND TO LESSEN THE TSTM THREAT ACROSS THE UPPER TX AND LA GULF COASTAL REGIONS THROUGH THE MORNING. CURRENT TSTMS SEEM TO BE TIED TO WAA OCCURRING WITH THE LOW LEVEL JET...AND SHOULD WEAKEN BY MID- MORNING. ADDITIONAL CONVECTION COULD DEVELOP JUST OFFSHORE THIS AFTERNOON IN SLIGHTLY MORE UNSTABLE AIRMASS AS THE WEAK FRONT MOVES TO THE COAST. ...UPPER OH VLY REGION INTO THE CNTRL APPALACHIANS... LAPSE RATES WILL STEEPEN CONSIDERABLY WITH THE APPROACH OF THE SHORTWAVE TROUGH /700-500 MB LAPSE RATES OF NEAR 8 C/KM/. BOUNDARY LAYER MOISTURE...REPRESENTED BY MID TO UPPER 40S DEW POINTS IN SRN KY ATTM...IS PROGGED TO ADVECT NEWD INTO THE MID OH VLY THIS AFTERNOON AND WILL LIKELY CONTRIBUTE TO MARGINAL INSTABILITY AS IT BECOME JUXTAPOSED WITH THE STEEPER LAPSE RATES. CONVECTION MAY DEVELOP ALONG THE ERN EDGE OF THE COMMA HEAD...NOW APPROACHING NRN IL...THIS MORNING...AND COULD BECOME VIGOROUS ENOUGH TO PRODUCE LIGHTNING AS IT MOVE EWD INTO THE MORE UNSTABLE AIRMASS. ...NRN FL... WEAK SURFACE TROUGH WILL CONTINUE OVER THE SERN FL COASTAL WATERS TODAY. LACK OF LARGE SCALE UVV AND MOIST ADIABATIC LAPSE RATES WILL LIMIT THE THREAT FOR TSTMS...ALTHOUGH AN ISOLATED LIGHTNING STRIKE IS NOT OUT OF THE QUESTION. ..RACY.. 11/29/00  ACUS3 KMKC 291350 SWOMCD MKC MCD 291349 ORZ000-WAZ000-291800- SPC MESOSCALE DISCUSSION 2030 FOR NORTH CENTRAL OR / EXTREME SOUTH CENTRAL WA CONCERNING...FREEZING RAIN... FREEZING RAIN AT A RATE OF AT LEAST 0.05 INCHES PER 3 HOURS IS EXPECTED TO DEVELOP OVER PORTIONS OF CENTRAL INTO NORTH CENTRAL ORE AND INTO EXTREME SOUTH CENTRAL WA DURING THE NEXT 1-2 HOURS. THE FREEZING RAIN IS THEN EXPECTED TO PERSIST THROUGH AT LEAST 29/18Z. REGIONAL 12Z SOUNDINGS OVER THE PACIFIC NORTHWEST SHOW A DRY LAYER IN THE LOW-MID LEVELS OVER THE AREA OF CONCERN. HOWEVER...THIS LAYER IS EXPECTED TO SATURATE AS PRECIPITATION OVER NRN CA INTO SWRN ORE TRACKS NEWD OVER THIS REGION DURING THE NEXT 1-2 HOURS. HOURLY SURFACE ANALYSES HAVE SHOWN A SHALLOW LAYER OF SUB-FREEZING AIR AT/NEAR THE SURFACE OVER CENTRAL ORE INTO SRN WA. THESE SURFACE TEMPERATURES ARE EXPECTED TO REMAIN BELOW 32 F THROUGH THE MORNING...RESULTING IN FREEZING RAIN. THERMODYNAMIC PROFILES FROM THE 06Z ETA POINT FORECAST SOUNDINGS SUPPORT THIS SCENARIO WITH FREEZING PRECIPITATION THROUGH AT LEAST 18Z. ..PETERS.. 11/29/00 ...PLEASE SEE WWW.SPC.NOAA.GOV/ FOR GRAPHIC PRODUCT...  ACUS1 KMKC 291629 SWODY1 MKC AC 291625 STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWBC. VALID 291630Z - 301200Z NO SVR TSTMS FCST. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 N AOO HGR 15 NNE ROA 25 N 5I3 60 E LUK DAY 30 SE FDY 20 SE CAK 30 NE PIT 20 N AOO. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 SSW HQM PDX 40 ESE EUG MFR MHS 35 NE RBL 50 SE RBL 45 S UKI. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 40 E PSX 35 N PSX 25 WNW HOU 40 NNW BPT POE 40 SSW HEZ 40 WSW HUM. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM EYW 15 SSE MIA. PROGRESSIVE UPPER FLOW PATTERN IS EVIDENT IN SATELLITE IMAGERY AS SERIES OF VORTICITY MAXIMA/SHORT WAVE TROUGHS MOVE EWD ACROSS THE ERN PACIFIC AND UPPER MS/OH VALLEYS. COMPLEX SYSTEM MOVING TOWARD THE PACIFIC NW IS FORECAST TO WEAKEN AS IT TRANSLATES INLAND LATER TODAY...WITH RIDGING ALOFT EXPECTED OVER WA/OREGON/NRN CA BY TONIGHT. DOWNSTREAM...NEGATIVE TILT TROUGH OVER THE UPPER MS/OH VALLEY REGION IS FORECAST TO MOVE RAPIDLY EWD IN ASSOCIATION WITH 100 KT MIDDLE LEVEL JET STREAK MOVING INTO THE BASE OF THE TROUGH. FARTHER SOUTH...SATELLITE IMAGERY SHOWS A WEAKENING POSITIVELY TILTED TROUGH MOVING EWD ACROSS THE CENTRAL GULF OF MEXICO. ...NRN PACIFIC COAST... APPROACHING UPPER TROUGH IS ASSOCIATED WITH COLD AIR ALOFT CONTRIBUTING TO STEEPENING LAPSE RATES IN THE POST-FRONTAL AIR MASS. SATELLITE IMAGERY SHOWS SEVERAL BANDS OF CONVECTIVE CLOUDS APPROACHING THE NRN CA AND OREGON COASTS...AND LIGHTNING DETECTION NETWORK HAS INDICATED ISOLATED THUNDERSTORMS DURING THE MORNING. A THREAT FOR A FEW THUNDERSTORMS SPREADING ONSHORE WILL CONTINUE THROUGH THE AFTERNOON WITH CONVECTIVE POTENTIAL DIMINISHING TONIGHT AS HEIGHTS RISE OVER THE AREA. ...OH VALLEY TO THE APPALACHIANS... VERY COLD AIR ALOFT /-32C AT 500 MB/ ACCOMPANYING THE VIGOROUS TROUGH OVER THE MS/OH VALLEY IS RESULTING IN STEEP LAPSE RATES AND MARGINALLY UNSTABLE ENVIRONMENT. STRONG DYNAMIC FORCING FOR UPWARD MOTION WITHIN LEFT EXIT REGION OF UPPER LEVEL JET STREAK HAS AIDED DEVELOPMENT OF LOW-TOPPED THUNDERSTORMS OVER PARTS OF OH THIS MORNING. A FEW THUNDERSTORMS ARE EXPECTED TO SPREAD EWD INTO PARTS OF SWRN PA AND WV THIS AFTERNOON AS THE UPPER TROUGH CONTINUES EWD. ...SERN TX/SWRN LA... BAND OF CONVECTION IS MOVING SEWD ALONG FRONTAL BOUNDARY INTO MARGINALLY UNSTABLE ENVIRONMENT. AN ISOLATED THUNDERSTORM MAY DEVELOP ALONG THE BAND AS IT MOVES TOWARD THE GULF COAST THIS AFTERNOON...BUT OVERALL THREAT APPEARS TO BE DIMINISHING AS UPPER LEVEL SUPPORT CONTINUES TO WEAKEN. ...EXTREME SRN FL... BAND OF THUNDERSTORMS HAS BEEN DEVELOPING SLOWLY NWWD ACROSS PARTS OF THE KEYS...AND ACTIVITY IS EXPECTED TO CONTINUE AS UPPER TROUGH APPROACHES FROM THE WEST AND INTERACTS WITH MOIST LOW LEVEL AIR MASS ACROSS EXTREME SRN FL. ..WEISS.. 11/29/00  ACUS2 KMKC 291723 SWODY2 MKC AC 291715 STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 2 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWI47 KWBC. VALID 301200Z - 011200Z NO TSTMS FCST. THE MID/UPPER PATTERN WILL REMAIN PROGRESSIVE THROUGH THE PERIOD ...AS A STRONG TROUGH NOW MOVING INTO NRN CA SHIFTS ACROSS THE CENTRAL U.S. HOWEVER...SURFACE ANTICYCLONE WILL MAINTAIN A MODIFIED CONTINENTAL AIRMASS WELL INTO THE GULF OF MEXICO AND LIMIT THE AVAILABILITY OF MOISTURE FOR DEEP CONVECTION. CONVECTION IS EXPECTED TO DEVELOP INVOF SURFACE COLD FRONT MOVING INTO ERN/CENTRAL TX FRIDAY MORNING...THOUGH ACTIVITY MAY HOLD OFF UNTIL JUST AFTER THIS FORECAST PERIOD. ..EVANS.. 11/29/00