Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 07/17/07

AREA FORECAST DISCUSSION
NWS RENO NV
905 PM PDT MON JUL 16 2007 .UPDATE... A BUSY SWING SHIFT BETWEEN SEVERE THUNDERSTORMS AND FIRE WEATHER CONCERNS! CONVECTION IS GENERALLY WINDING DOWN WITH LOSS OF DAYTIME HEATING. EARLIER WE HAD REPORTS OF WIND DAMAGE NEAR FALLON ASSOCIATED WITH A SMALL LINE SEGMENT MOVING THROUGH WESTERN CHURCHILL COUNTY. TRAINING CELLS OVER PORTIONS OF MINERAL AND SOUTHERN LYON COUNTY LIKELY PRODUCED AT LEAST 1.5 INCHES OF RAIN BASED ON CALIBRATED RADAR ESTIMATES. WILL CONTINUE SLT CHCS OF -SHRA OVERNIGHT IN CAZ073 INTO NVZ001/004 WITH SHORTWAVE LIFTING NORTH INTO THE REGION COUPLED WITH REASONABLY MOIST AIRMASS. SOME ISLTD -SHRA HAVE RECENTLY DEVELOPED JUST EAST OF US 395 IN MONO COUNTY. PRIMARY FOCUS TONIGHT WILL BE DEALING WITH AREAS OF SMOKE... ESPECIALLY IN THE RENO METRO ASSOC WITH HAWKINS FIRE. WESTERLY LOW LEVEL WINDS ARE PUSHING A PLUME OF SMOKE ACROSS SRN SECTIONS OF THE CITY. BUT RECENT AIRCRAFT/MDCRS WIND REPORTS SHOWING SLY FLOW AOA 10KFT MSL...AND WE`RE ALSO SEEING SOME SMOKE DRIFT NORTHWARD ONCE IT HITS A HIGH ENOUGH ALTITUDE. WE ARE EXPECTING SMOKE TO SETTLE AND SPREAD OUT OVERNIGHT AS WINDS LIGHTEN BUT HIGHER ALTITUDE WINDS WILL LIKELY REMAIN UP OVERNIGHT AS SHORTWAVE MOVES THROUGH. WILL ADD AREAS OF SMOKE TONIGHT INTO EARLY TUESDAY MORNING TO THE FCST FOR THE RENO-SPARKS VICINITY AND OVER A SMALL PART OF MONO COUNTY NEAR THE CONWAY FIRE. HAVE ISSUED AN SPS FOR RESTRICTED VSBYS IN THE VICINITY OF RENO. WILL NEED TO EVALUATE LATER WHETHER A DENSE SMOKE ADVISORY IS WARRANTED. WILL LOWER TEMPS A COUPLE DEGREES IN THE ERN ZONES WHERE RAIN COOLED AIRMASS EXISTS. REST OF FCST UNCHANGED. UPDATE OUT BY 930 PM PDT. CS && .SHORT TERM... UPPER TROUGH CONTINUES TO APPROACH THE WEST COAST WITH S/W OVER THE SOUTHWEST U.S. BEGINNING TO EJECT NORTHEASTWARD TOWARD NEVADA. CUMULUS DEVELOPMENT HAS BEEN SLOW AND DISORGANIZED THUS FAR BASED ON AREA WEBCAMS WITH MOST OF THE CONVECTION THROUGH EARLY AFTERNOON RESIDING OVER THE NORTHEAST CORNER OF THE STATE. AS UPPER JET MOVES CLOSER GENERAL LARGE SCALE LIFT SHOULD INCREASE AND HELP TO FOCUS THUNDERSTORM DEVELOPMENT IN AREAS OF INSTABILITY. THE BEST COVERAGE WILL BE ALONG THE CONVERGENCE ZONE (MONO-MINERAL-EASTERN CHURCHILL COUNTIES) WITH MORE ISOLATED CELLS EXTENDING WESTWARD TO ALPINE COUNTY AND UP THE PINE NUT/VIRGINIA RANGES. CONVECTION MAY LINGER PAST MIDNIGHT SO ISOLATED POPS WERE MAINTAINED EASTERN ZONES. SOUTHWEST FLOW WILL INCREASE TUESDAY AND ESPECIALLY WEDNESDAY WITH PASSAGE OF COLD FRONT. LAKE WIND ADVISORIES WILL BE RAISED NORTHWEST AREAS TUESDAY AND WILL BE NEEDED MANY AREAS FOR WEDNESDAY. SEE FIRE DISCUSSION BELOW FOR FURTHER IMPACTS FROM THE WIND. THERE IS STILL SOME SUGGESTION THAT JET SUPPORT MAY BE SUFFICIENT TO PRODUCE SHOWERS ACROSS THE NORTHERN HALF OF AREA LATE WEDNESDAY. OTHERWISE COOLER TEMPERATURES ON TAP FOR WEDNESDAY WITH ONLY SLIGHT MODERATION THURSDAY AS TEMPERATURES HANG NEAR OR SLIGHTLY BELOW NORMAL. HOHMANN .LONG TERM...FRIDAY THROUGH MONDAY... RIDGE REBUILDS OVER THE FOUR CORNERS REGION WITH WARMER AIR MASS RETURNING TO WRN NV-ERN CA. MAX TEMPS LIKELY TO JUMP 8-10 DEGREES IN COMPARISON TO THURS AS 700 MB TEMPS RISE ABOUT 4 DEGREES C WITH NO CLOUD COVER. FURTHER WARMING IS LIKELY SATURDAY AS RIDGE STRENGTHENS OVER THE NRN-CNTRL ROCKIES AND EXPANDS IN EAST-WEST COVERAGE. MAX TEMPS WILL GET CLOSE TO 100 IN MOST WRN NV VALLEYS WITH LOWER 100S IN W-CNTRL NV. BY SUN-MON...THE GFS AND ECMWF BEGIN TO OFFER DIVERGING SOLUTIONS. THE GFS BUILDS THE RIDGE FARTHER NORTH WITH 600 DM CENTER IN MONTANA WHICH ALLOWS MONSOON MOISTURE TO SPREAD NORTH INTO CENTRAL NV-CA WHILE THE ECMWF BRINGS NEXT TROF TOWARD THE WEST COAST. THE CONTRASTS INCREASE ON MONDAY AS THE ECMWF DROPS 500 MB HEIGHTS BACK TO 585 DM WITH INCREASE IN STABLE SW FLOW...BUT GFS KEEPS HEIGHTS IN THE LOW 590S WHILE SPREADING MONSOON MOISTURE AND INSTBY ACROSS ALL OF THE FORECAST AREA. FOR THIS TIME OF YEAR...IT IS REASONABLE TO EXPECT THE MONSOON TO MAKE SOME NORTHWARD PROGRESS AND ALSO CONSIDERING THE EXPECTED STRENGTH OF THE RIDGE...THE NEXT APPROACHING TROF WILL HAVE A TOUGH TIME BREAKING IT DOWN QUICKLY. EVENTUAL WEAKENING OF THE RIDGE SHOULD OCCUR TOWARD THE MIDDLE OF NEXT WEEK...BUT UNTIL THEN ANOTHER 100 DEGREE DAY IS LIKELY IN THE VALLEYS ON SUNDAY WITH ONLY A SLIGHT DROP IN MAX TEMPS MONDAY DUE TO INCREASED CLOUD COVER AND POTENTIAL FOR TSTMS. THE PRESENCE OF MORE CLOUDS ALSO REQUIRED RAISING MIN TEMPS A FEW DEGREES STARTING SUN NIGHT. THE THREAT OF TSTMS WAS LIMITED TO AREAS SOUTH OF HIGHWAY 50 IN NV AND ALONG THE SIERRA CREST FROM TAHOE SOUTHWARD ON SUNDAY...THEN EXPANDED TO THE REMAINDER OF THE REGION FOR MONDAY. MJD && .AVIATION... ISOLD TO SCT -TSRA WITH BRIEF MVFR CONDS SOUTH AND EAST OF A KTVL-KLOL LINE THRU 04Z...WITH ISOLD -TSRA EAST OF HWY 95 OVERNIGHT. OTHERWISE VFR THRU TUESDAY WITH SW-W ZEPHYR WIND GUSTS TO 25 KT THRU 04Z THIS EVENING AND 25-30 KT GUSTS TUESDAY BTWN 22Z-04Z MJD && .FIRE WEATHER... ISOLATED TO SCATTERED THUNDERSTORMS MAINLY OVER MINERAL AND SRN LYON COUNTY WILL MOVE NORTHEAST 10-15 MPH. THESE THUNDERSTORMS WILL LIKELY SPARK SOME FIRES OUTSIDE OF THE WET CORES...HOWEVER THUNDERSTORMS WILL DEVELOP AND MOVE OVER THE SAME AREAS SO THERE IS A GOOD CHANCE THESE NEW FIRE STARTS MAY GET SOME RAIN OVER THEM THIS AFTERNOON. THE NEXT MAIN CONCERN WILL THE BE THE WIND AHEAD OF A COLD FRONT MOVING IN FROM THE PACIFIC. WINDS WILL STILL BE GUSTY TODAY...GENERALLY 25-30 MPH IN MOST AREAS WEST OF HIGHWAY 395. BY TOMORROW WINDS WILL REALLY PICK UP NORTH OF INTERSTATE 80 WHILE CONDITIONS REMAIN CRITICALLY DRY. GRADIENTS TIGHTEN AND 700 MB FLOW STARTS TO INCREASE TO 20-25KTS. THEREFORE RED FLAG WARNINGS WERE ISSUED FOR ZONES 272/271/278/270 AND 450/458. AREAS SOUTH AND EAST WILL SEE WIND GUSTS IN THE 25-30 MPH RANGE ON TUESDAY. BY WEDNESDAY THE FRONT MOVES CLOSER WITH A MUCH TIGHTER SURFACE GRADIENT AND 700 MB FLOW INCREASING TO 25-35 KTS. FIRE WEATHER WATCHES WERE ISSUED FOR NV ZONES 450/453/459 AND CA ZONE 273 FOR WEDNESDAY. THE MAIN QUESTION IN TAHOE AND AREAS NORTH WILL BE RH RECOVERY AND INCREASE. MOISTURE WILL MOVE IN AHEAD OF THE FRONT WITH INCREASING HUMIDITIES...HOWEVER ZONE 458 AND THE TAHOE BASIN WILL NEED TO BE WATCHED AS STRONG DOWNSLOPE WINDS IN 458 MAY COUNTERACT THE HUMIDITY INCREASE AND STILL DRY THINGS OUT. THE TAHOE BASIN MIGHT BE JUST FAR SOUTH ENOUGH TO NOT SEE THE HUMIDITY INCREASES THAT WILL MAKE MUCH DIFFERENCE. MID SHIFT CAN TAKE A LOOK AND ADD THOSE AREAS TO THE WATCH IF NEED BE. BENINATO .REV WATCHES/WARNINGS/ADVISORIES... NV...RED FLAG WARNING FROM 1 PM TO 9 PM PDT TUESDAY FOR NVZ450-458. FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY EVENING FOR NVZ450-453-459. CA...RED FLAG WARNING FROM 1 PM TO 9 PM PDT TUESDAY FOR CAZ270>272- 278. FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY EVENING FOR CAZ273. && $$ HTTP://WEATHER.GOV/RENO
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NWS LOS ANGELES/OXNARD CA
500 AM PDT SUN JUL 15 2007 ...UPDATED AVIATION SECTION... .SHORT TERM... AN EDDY IS JUST STARTING TO SPIN A 600 FOOT (PER ACARS) MARINE LAYER AROUND THE SO CAL COAST. ALONG THE CENTRAL COAST THE MARINE LAYER IS WELL ESTABLISHED AND HAS PUSHED DEEP INTO THE SANTA YNEZ VALLEY. PRESSURE GRADS ARE TRENDING MORE ONSHORE BOTH N/S AND W/E WHICH WILL HINDER BURN OFF...STILL THINK THERE WILL BE A COMPLETE BURN OFF BUT MAYBE NOT UNTIL MARINE LAYER SHOULD BE TOO SHALLOW TO ALLOW VLY PENETRATION BUT WITH EDDY LOOKING FAIRLY ROBUST THERE IS A CHANCE OF A SUNRISE SURPRISE. CONVECTION IS THE OTHER PROBLEM OF THE DAY. SOUTH FLOW WILL BRING SOME 600MB MOISTURE INTO THE AREA. BUFR SOUNDINGS SHOW SOME INSTABILITY BUT THE DRY SW FLOW AT 850 AND 700 MB SHOULD REALLY LIMIT THUNDER TO A SLIGHT CHANCE. A LITTLE DRIER MONDAY. EDDY AND THE MARINE LAYER WILL CONTINUE. STILL CONFINED TO THE COASTS. WITH DRIER FLOW ALOFT NO THREAT OF TSRA BUT THERE STILL MAY BE SOME BUILD UPS OVER THE VTA AND LA MTNS. A SUNDOWNER IS POSSIBLE TONIGHT AND MONDAY NIGHT. ALTHOUGH NOT SURE WHY NOTHING HAPPENED TODAY...THE GRADIENTS SEEM TO BE GOOD FOR A WEAK EVENT EACH NIGHT. BACK TO NIGHT AND MORNING CLOUD REGIME TUESDAY AS THE UPPER HIGHS SHIFTS EASTWARD AND ALLOWS THE SW FLOW ASSOC WITH A PAC NW LOW TO MOVE OVER SOCAL WHICH WILL PUT THE KIBOSH ON ANY CONVECTIVE THREAT. INCREASING ONSHORE FLOW AND LIFT ASSOC WITH THE CYCLONIC FLOW WILL BOOST THE MARINE LAYER INTO VALLEYS. .LONG TERM... A GENERAL MARINE LAYER PATTERN CONTINUES THROUGH THE REST OF THE PERIOD. A LITTLE NORTH PUSH WILL LESSEN THE MARINE CLOUDS WED NIGHT AND THU. HIGHER HGTS NEXT WEEKEND SHOULD SQUASH THE MARINE LAYER BACK TO THE COASTS AND WARM THINGS UP. && .AVIATION...15/1200Z. NW FLOW HAS BROUGHT LIFR CIGS TO KSBP AND KSMX. WEAK COASTAL EDDY WILL SOON BRING IFR CIGS TO KLAX AND KLGB. EXPECT A LATE ARRIVAL AT KOXR...BUT HIGH CLOUDS MAY PREVENT FORMATION KSBA SHOULD REMAIN CIG FREE. BURN OFF SHOULD OCCUR BY 17-19Z. SIMILAR ARRIVAL TIMES FOR MARINE LAYER EXPECTED TONIGHT. KLAX...IFR CIGS ARE ON THE BRINK OF THE AIRFIELD AND SHOULD ARRIVE SHORTLY. CLEARING EXPECTED BY 19Z...BUT NOT CONFIDENT IN TIMING FOR THE RETURN OF THE MARINE LAYER TONIGHT. KBUR...VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD....WITH A USUAL AFTERNOON SOUTH BREEZE NEAR 8 KT. $$ .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXCWFLOX). && $$ PUBLIC...RORKE AVIATION...MEIER WWW.WEATHER.GOV/LOSANGELES
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
320 AM PDT SUN JUL 15 2007 .SHORT TERM... AN EDDY IS JUST STARTING TO SPIN A 600 FOOT (PER ACARS) MARINE LAYER AROUND THE SO CAL COAST. ALONG THE CENTRAL COAST THE MARINE LAYER IS WELL ESTABLISHED AND HAS PUSHED DEEP INTO THE SANTA YNEZ VALLEY. PRESSURE GRADS ARE TRENDING MORE ONSHORE BOTH N/S AND W/E WHICH WILL HINDER BURN OFF...STILL THINK THERE WILL BE A COMPLETE BURN OFF BUT MAYBE NOT UNTIL MARINE LAYER SHOULD BE TOO SHALLOW TO ALLOW VLY PENETRATION BUT WITH EDDY LOOKING FAIRLY ROBUST THERE IS A CHANCE OF A SUNRISE SURPRISE. CONVECTION IS THE OTHER PROBLEM OF THE DAY. SOUTH FLOW WILL BRING SOME 600MB MOISTURE INTO THE AREA. BUFR SOUNDINGS SHOW SOME INSTABILITY BUT THE DRY SW FLOW AT 850 AND 700 MB SHOULD REALLY LIMIT THUNDER TO A SLIGHT CHANCE. A LITTLE DRIER MONDAY. EDDY AND THE MARINE LAYER WILL CONTINUE. STILL CONFINED TO THE COASTS. WITH DRIER FLOW ALOFT NO THREAT OF TSRA BUT THERE STILL MAY BE SOME BUILD UPS OVER THE VTA AND LA MTNS. A SUNDOWNER IS POSSIBLE TONIGHT AND MONDAY NIGHT. ALTHOUGH NOT SURE WHY NOTHING HAPPENED TODAY...THE GRADIENTS SEEM TO BE GOOD FOR A WEAK EVENT EACH NIGHT. BACK TO NIGHT AND MORNING CLOUD REGIME TUESDAY AS THE UPPER HIGHS SHIFTS EASTWARD AND ALLOWS THE SW FLOW ASSOC WITH A PAC NW LOW TO MOVE OVER SOCAL WHICH WILL PUT THE KIBOSH ON ANY CONVECTIVE THREAT. INCREASING ONSHORE FLOW AND LIFT ASSOC WITH THE CYCLONIC FLOW WILL BOOST THE MARINE LAYER INTO VALLEYS. .LONG TERM... A GENERAL MARINE LAYER PATTERN CONTINUES THROUGH THE REST OF THE PERIOD. A LITTLE NORTH PUSH WILL LESSEN THE MARINE CLOUDS WED NIGHT AND THU. HIGHER HGTS NEXT WEEKEND SHOULD SQUASH THE MARINE LAYER BACK TO THE COASTS AND WARM THINGS UP. && .AVIATION... 15/1030Z ...WILL BE UPDATED AROUND 1130Z WITH THE 12Z TAF PACKAGE... $$ .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXCWFLOX). && $$ PUBLIC...RORKE AVIATION...MEIER WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS MIAMI FL
240 PM EDT SUN JUL 15 2007 .DISCUSSION...SURFACE OBSERVATIONS SUGGEST THAT THE SURFACE RIDGE AXIS STRETCHES ACROSS THE KEYS AND SOUTHERN SECTIONS OF THE CWA. SEA BREEZES ARE OCCURRING ALONG THE COASTS...BUT C-MAN STATIONS AT THE KEYS AS WELL AS SETTLEMENT PT SHOW S TO SW FLOW. ACARS DATA CONTINUES TO SHOW A SW STEERING FLOW...THOUGH LIGHTER THAN THIS MORNING. SO THE EXPECTATION IS FOR CONVECTION TO CONTINUE TO INCREASE IN BOTH COVERAGE AND INTENSITY AS THE SEA BREEZES MOVE INLAND. STEERING FLOW FAVORS CONVECTION TO CONCENTRATE OVER THE EASTERN HALF OF THE AREA LATE THIS AFTERNOON INTO EARLY THIS EVENING...SO CONTINUED WITH THE HIGHEST POPS INTERIOR/EAST COAST...WITH LESSER POPS ALONG THE GULF COAST. ONCE ACTIVITY WANES TONIGHT...A TRANQUIL NIGHT IS EXPECTED ACROSS MOST OF THE AREA...WITH JUST A SLIGHT CHANCE OF ACTIVITY ALONG THE ATLANTIC COAST AS AN E-SE FLOW TRIES TO BUILD IN. GFS AND NAM ARE CONSISTENT IN LIFTING THE ATLANTIC RIDGE NORTH ON MONDAY...BUT LATELY THIS RIDGE SEEMS TO NOT WANT TO BUDGE. HOWEVER...WILL GO WITH THIS SCENARIO AS IT DOES LOOK LIKE THE UPPER TROUGH OVER THE LOWER MS VALLEY IS MOVING A LITTLE SW. SO WILL GO WITH A FCST OF PREVAILING WINDS BECOMING E-SE...WHICH WILL FOCUS AFTERNOON CONVECTION THE NEXT FEW DAYS OVER INTERIOR/GULF COASTAL LOCATIONS. THERE IS A LOW/MID LEVEL TROUGH APPROACHING THE BAHAMAS...AND THIS WILL MOVE ACROSS THE AREA ON MONDAY AFTERNOON. IF THERE WAS DEEPER MOISTURE MOVING IN ALONG WITH THIS FEATURE...THEN WOULD INCREASE POPS. HOWEVER...MOVING PWAT IMAGERY SHOWS DRIER AIR UPSTREAM OF OUR AREA AND THIS WILL MOVE IN TOMORROW. THUS...WILL KEEP LOW CHANCE POPS EAST COAST AND HIGH CHANCE INTERIOR AND GULF COAST. THE TROPICAL WAVE MOVING ACROSS THE WINDWARD ISLAND CHAIN WILL CONTINUE TO MOVE ALONG AT A BRISK PACE AND PASS SOUTH OF THE AREA LATER ON TUESDAY. HOWEVER...MOISTURE WILL INCREASE ACROSS THE AREA AS WINDS TURN SE MIDWEEK. NO MAJOR CHANGES IN THE WEATHER PATTERN ARE EXPECTED LOCALLY...WITH A CONTINUATION OF THE TYPICAL DIURNAL CONVECTIVE PATTERN AND FAVORING INTERIOR/GULF COASTAL LOCATIONS EACH AFTERNOON. MADE NO SIGNIFICANT CHANGES TO THE EXTENDED FCST. && .AVIATION...THE SEA BREEZE ALONG BOTH THE EAST AND WEST COASTS HAVE PUSHED INLAND ENOUGH TO GENERALLY KEEP ALL TAFS ON THE EAST COAST WITH A SOUTHEASTERLY WIND AND APF WITH A SOUTHWEST WIND, HOWEVER SLIGHTLY ABOVE THE SURFACE THERE REMAINS A SOUTHWEST FLOW. THIS WILL CONTINUE TO ALLOW THE WEST COAST SEA BREEZE TO PUSH WELL INLAND AND COLLIDE WITH THE EAST COAST SEA BREEZE. THIS WILL KEEP SHOWERS AND THUNDERSTORMS AROUND THE EAST COAST INTO THE EVENING, AND WITH STORMS PRESENT WIND DIRECTION AND SPEED IS ALSO DEPENDANT ON OUTFLOW BOUNDARIES. VCTS HAS BEEN LEFT IN THE TAFS DUE TO FORECAST TIMING DIFFICULTIES. AS THE EVENING PROGRESSES THE ACTIVITY WILL BEGIN TO DECREASE IN COVERAGE AND INTENSITY. && .MARINE...SURFACE RIDGE LOOKS TO FINALLY MOVE FAR ENOUGH NORTH TO ALLOW WINDS TO PREVAIL OUT OF THE SOUTHEAST...INCREASING INTO THE 10 TO 15 KT RANGE BY TUESDAY. NO HIGHLIGHTS NECESSARY. && .FIRE WEATHER...NO CONCERNS ASIDE FROM LIGHTNING STRIKES FROM THUNDERSTORMS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 79 89 81 89 / 40 30 30 50 FORT LAUDERDALE 80 88 80 89 / 40 30 30 50 MIAMI 79 90 80 89 / 40 30 30 50 NAPLES 75 92 75 92 / 30 50 20 50 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE WEATHER...57/DG AVIATION...04/AT
AREA FORECAST DISCUSSION
NWS MIAMI FL
938 AM EDT SUN JUL 15 2007 .UPDATE...SIGNIFICANT CHANGES WERE MADE TO THE FORECAST FOR THIS AFTERNOON BASED ON LATEST DATA. DESPITE ALL MODELS SHOWING THE RIDGE MOVING NORTH WITH A SE WIND FLOW PREVAILING...THAT IS JUST NOT HAPPENING. IN FACT...ACARS DATA OUT OF MIA AND FLL SHOWS WINDS OUT OF THE SOUTHWEST IN THE LOW/MID LEVELS...AND EVEN IN THE 10-15 KT RANGE AT NEAR 3K FT. THIS IS A DRASTIC DIFFERENCE IN ALL MODEL OUTPUT...SO MODELS WILL BE COMPLETELY IGNORED FOR WHAT IS EXPECTED THIS AFTERNOON. GIVEN THIS WIND FLOW PATTERN...HEATING THIS MORNING WILL ALLOW WINDS TO BECOME SOUTHWEST AT AROUND 10 KNOTS BEFORE A SEA BREEZE DEVELOPS ALONG THE ATLANTIC COAST. THE SEA BREEZE LIKELY WILL NOT PENETRATE TOO FAR INLAND THIS AFTERNOON GIVEN THE FLOW I SEE IN ACARS. THUS...BEST CONVERGENCE THIS AFTERNOON LOOKS TO SET UP ACROSS PALM BEACH...BROWARD...AND MIAMI- DADE COUNTIES...INCLUDING THE EAST COAST METROPOLITAN AREAS. SO ADJUSTED POPS ACCORDINGLY. THIS IS MORE OF A SIGNIFICANT CHANGE THAN NORMALLY DONE IN AN UPDATE...BUT THE CURRENT DATA SUPPORTS THIS. IT SHOULD BE NOTED THAT THE WINDS IN THE MIA SOUNDING THIS MORNING WERE UNAVAILABLE IN THE LOW LEVELS...AND SO THE LIGHTER WINDS IN THE LOW LEVELS THAT ONE MIGHT SEE DEPICTED IN THE SOUNDING ARE NOT REAL...THOSE WINDS DEPICTED APPARENTLY ARE JUST AN EXTRAPOLATION FROM THE SURFACE TO MID LEVELS. PWAT IS EXACTLY THE SAME AS YESTERDAY...AND NUMEROUS SHRA/TSRA AFFECTED THE LAKE OKEECHOBEE REGION YESTERDAY...AND SEE NO REASON THIS WILL NOT HAPPEN ACROSS THE EASTERN HALF OF THE AREA THIS AFTERNOON...GIVEN DECENT MOISTURE...HIGH CAPE...AND VERY GOOD CONVERGENCE ONCE THE SEA BREEZE FORMS. THERE IS A LESSER CHANCE OF STORMS ACROSS THE GREATER NAPLES AREA TODAY...BUT STILL KEPT POPS IN CHANCE RANGE AS STRONG HEATING COULD LEAD TO THE DEVELOPMENT OF SCT SHRA/TSRA THERE. SOME OF THE STORMS COULD BECOME STRONG...WITH STRONG WIND GUSTS BEING THE PRIMARY THREAT. SOME WARMING OCCURRED IN THE MID LEVELS...SO SMALL HAIL IS LESS OF A POTENTIAL...BUT STILL CANNOT BE RULED OUT. ALSO...WE ARE GOING TO SHOW A SLIGHT RISK OF TORNADOES ACROSS PALM BEACH...BROWARD...AND MIAMI-DADE COUNTIES FOR THIS AFTERNOON...BECAUSE ONCE THE ATLANTIC SEA BREEZE FORMS...SHOULD THE LOW LEVEL SW FLOW AT 10-15 KTS BE MAINTAINED THIS AFTERNOON...THIS WOULD RESULT IN DECENT HELICITY POSSIBLY LEADING TO A BRIEF SMALL TORNADO. /GREGORIA && .AVIATION...MOST OF THE DAY STILL EXPECTING VFR CONDITIONS, HOWEVER A MORE SOUTHWEST FLOW ACROSS THE AREA IS NOW ANTICIPATED. THIS MAY KEEP MORE SHOWERS AND THUNDERSTORMS ACROSS THE EAST COAST METRO AREAS AS THE SEA BREEZE WILL LIKELY NOT BE ABLE TO PUSH FAR INLAND. THESE SHOWERS AND STORMS MAY CAUSE MVFR AND POSSIBLY BRIEF PERIODS OF IFR CONDITIONS. THE WEST COAST THE SEA BREEZE WILL LIKELY DEVELOP AND PUSH INLAND RAPIDLY KEEPING MOST ACTIVITY AWAY FROM APF... WILL KEEP VCTS FOR NOW IN ALL TAFS DUE TO TIMING AND DURATION DIFFICULTIES. /TINGLER && .PREV DISCUSSION... /ISSUED 416 AM EDT SUN JUL 15 2007/ DISCUSSION...IN THE NEAR TERM...A WEAK LAND BREEZE HAS BEEN TRYING TO SET UP THIS MORNING ALONG THE EAST COAST...WITH MOST SITES REPORTING INTERMITTENT NW WINDS. THIS HAS LED TO CONVERGENCE ACROSS THE ATLANTIC WATERS AND THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS. A FEW CELLS HAVE APPROACHED THE IMMEDIATE COAST BUT MOST REMAIN OFFSHORE...AND WOULD EXPECT THIS TREND TO CONTINUE THROUGH SUNRISE AS LONG AS LAND BREEZE KEEPS BLOWING...BUT A FEW SHOWERS MAY CREEP ONSHORE AFTER SUNRISE AS SEA BREEZE DEVELOPS. DEEP LAYERED RIDGE AXIS REMAINS IN PLACE ACROSS CENTRAL/SOUTH FL BUT SLOWLY BEGINS A NORTHWARD SHIFT THE NEXT SEVERAL DAYS. THIS WILL ALLOW A GRADUAL INCREASE IN MOISTURE THROUGH THE MID WEEK PERIOD WITH THE EXCEPTION OF MONDAY...MORE ON THAT SHORTLY. GENERAL EAST/SOUTHEAST FLOW WILL CONTINUE. FOR TODAY...MODEL FORECAST SOUNDINGS INDICATE A FAIRLY DEEP/STRONG EASTERLY WIND FLOW AND THIS SHOULD ONCE AGAIN FAVOR INTERIOR AND WESTERN AREAS FOR CONVECTION AS THE EAST COAST SEA BREEZE SHOULD SCREAM INLAND ONCE THE MORNING LAND BREEZE DISSIPATES WITH THE ONSET OF DAYTIME HEATING. EXPECT ACTIVITY TO CONCENTRATE NEAR/SOUTH/SOUTHWEST OF LAKE OKEECHOBEE ONCE AGAIN TODAY AS INSTABILITY GRADUALLY INCREASES AND PWATS CLIMB TO 2 INCHES IN THIS FAVORABLE REGION OF SEA BREEZE CONVERGENCE FROM BOTH COASTS. THE TROPICAL WAVE CURRENTLY APPROACHING THE WINDWARD ISLANDS WILL PASS JUST SOUTH OF THE REGION ON TUESDAY...BUT THE WAVE APPEARS TO BE TILTED TO THE WEST WITH HEIGHT AND A MID LEVEL TROUGH WILL PASS SOUTH OF THE REGION MONDAY AS A RESULT...AND WILL BE ENHANCED BY AN UPPER LOW AHEAD OF THE WAVE IN THE VICINITY OF 20N/70W. WHILE THE APPROACH OF A MID LEVEL TROUGH WOULD NORMALLY ARGUE FOR HIGHER POPS...MIMIC PRECIPITABLE WATER LOOPS FROM THE UNIVERSITY OF WISCONSIN SHOW A LARGE RESERVOIR OF DRIER AIR PRECEDING THE TROPICAL WAVE ACROSS THE CENTRAL ATLANTIC...AND MODEL SOUNDINGS DRY OUT QUITE A BIT FROM TODAY ACROSS THE REGION AS A RESULT. THUS THINK MONDAY HAS THE POTENTIAL TO BE A BIT OF A DRIER DAY...ESPECIALLY ALONG THE EAST COAST AS SEA BREEZE SHOULD ONCE AGAIN SCREAM INLAND AND FOCUS CONVECTIVE CHANCES ACROSS THE WESTERN INTERIOR. AS THE TROPICAL WAVE PASSES SOUTH OF THE REGION ON TUESDAY...MODELS CONTINUE TO INDICATE THE NORTHERN END OF THE WAVE AXIS WILL BE CLOSE ENOUGH TO PROVIDE SOME ENHANCED CONVERGENCE AND THUS FAIRLY GOOD CHANCES FOR PRECIPITATION MOVING FROM WEST TO EAST DURING THE DAY WITH THE WAVE PASSAGE. THEREAFTER...A SECOND UPPER LOW CURRENTLY NEAR 30N/55W CONTINUES TO RETROGRADE SOUTHWEST TO SOUTH OF BERMUDA...OPENING A WEAKNESS IN THE MID/UPPER RIDGE ACROSS FL AND THE WESTERN ATLANTIC. IN RESPONSE, THE SURFACE RIDGE SHIFTS SLIGHTLY FURTHER EAST INTO THE ATLANTIC, ALLOWING FOR A MORE SOUTHERLY TO SOUTH SOUTH SOUTHEASTERLY SURFACE WIND FLOW WITH LIGHTER MID/UPPER LEVEL FLOW. THIS SHOULD CONTINUE TO FAVOR INTERIOR LOCATIONS FOR CONVECTION BUT COULD LEAD TO HIGHER CHANCES ACROSS THE EAST COAST METRO AREAS AS WINDS ARE MORE PARALLEL TO THE COAST AND STEERING FLOW IS WEAKER. THE WEST COAST SEA BREEZE SHOULD PUSH A GOOD DEAL INLAND TODAY AND AS SUCH CONVECTIVE CHANCES ALONG THE IMMEDIATE WEST COAST SHOULD BE LIMITED TO THE MIDDAY HOURS AS IT PUSHES INLAND AND THE EVENING HOURS AS STORMS MAY PROPAGATE BACK WESTWARD ALONG OUTFLOWS. AVIATION...MAINLY VFR CONDITIONS EXPECTED ALL TERMINALS THROUGH REST OF NIGHT AND MOST OF MORNING. ONLY POSSIBILITY OF LOWER THAN VFR IS FROM COASTAL SHOWER ACTIVITY EARLY THIS MORNING FROM KFLL NORTHWARD. SOME SHOWER ACTIVITY WILL MOVE NORTHWEST THROUGH THE MORNING HOURS EASTERN COASTAL AREAS AND MOVE INLAND AND INCREASE IN THE AFTERNOON AS THE SEABREEZES PUSH ACTIVITY INLAND. VCTS IN ALL TAFS AFT 16/17Z. MARINE...WINDS WILL REMAIN GENERALLY EAST/SOUTHEAST AROUND 10 KNOTS...THOUGH AN INCREASE TO NEAR 15 KNOTS IS POSSIBLE WITH PASSAGE OF TROPICAL WAVE AXIS MONDAY NIGHT-TUESDAY NIGHT. FIRE WEATHER...NO CONCERNS OUTSIDE OF LIGHTNING STRIKES FROM THUNDERSTORMS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 90 77 89 77 / 60 30 40 20 FORT LAUDERDALE 90 79 89 79 / 60 30 40 20 MIAMI 91 77 90 77 / 60 30 40 20 NAPLES 92 74 92 74 / 40 30 40 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1220 AM CDT SUN JUL 15 2007 .DISCUSSION... EVENING UPDATE 800 PM CDT TOOK OUT THE CHANCE FOR ANY STORM DEVELOPMENT THIS EVENING AS THE THE CURRENT CU FIELD IS FAIRLY WEAK...WITH HARDLY ANY TCU TO SPEAK OF. STORM DEVELOPMENT CURRENTLY ONGOING ACROSS NORTHERN MISSOURI INTO WEST CENTRAL ILLINOIS IN ASSOCIATION WITH A SFC WAVE PROPAGATING ALONG THE COLD FRONT IN NORTHERN MISSOURI. THIS WAVE IN TURN HAS SUPPLIED MOISTER AIR TO THAT REGION...WHILE DEW POINTS ACROSS NORTHERN ILLINOIS AND INDIANA ARE STRUGGLING TO GET ABOVE 60...WHICH IS MUCH LOWER THAN HAD BEEN ANTICIPATED. COLD FRONT IS ALMOST THROUGH THE ENTIRE CWA AND SUBSIDENCE BEHIND THIS FRONT SHOULD LEAD TO A MAINLY CLEAR NIGHT. HALBACH && 259 PM CDT MAIN SHORT TERM FOCUS IS ON DWINDLING PRECIP THREAT AHEAD OF SFC COLD FRONT. VAPOR IMAGERY SHOWS MID LVL S/WV ACROSS NRN LAKES/SRN ONTARIO THIS AFTERNOON WITH ASSOCIATED SFC LOW PRESSURE REFLECTION OVER NRN LAKE HURON AT 18Z. WEAK SFC COLD FRONT TRAILS THROUGH IL/WI BORDER REGION...WITH WIND SHIFT AT KRFD NOTED WITHIN PAST 30 MIN. SFC DWPTS IN UPPER 50S/LOW 60S ACROSS FCST AREA AHEAD OF FRONT...CONTINUE TO BE SOME 5-8 DEG F LOWER THAN WRF/RUC FCSTS RESULTING IN LITTLE INSTABILITY AND ONLY WEAK CONVERGENCE ALONG/AHEAD OF BOUNDARY THIS AFTN. SPC RUC MESOANALYSIS GRAPHICS INDICATE LESS THAN 500 J/KG MLCAPE...AND 19Z ACARS DESCENT SOUNDING FROM KRFD CONFIRMS THIS WITH LITTLE/NO CAPE AND RELATIVELY WARM TEMPS IN 750-800 HPA LAYER. MODIFIED ACARS SOUNDINGS FROM KORD/KMDW WHEN MODIFIED FOR LOW 80/LOW 60S T/TD COMBO SUGGESTS PERHAPS 500 J/KG SBCAPE WITH SKINNY PROFILE...SO AM HESITANT TO REMOVE POPS ALTOGETHER REMAINDER OF AFTN/EARLY EVE...THOUGH BASED ON STATED TRENDS WILL LIMIT TO ISOLATED MENTION MAINLY SOUTH OF I88/I80 CORRIDOR. WITH LOSS OF DIURNAL INSTABILITY SHOULD SEE ANY ISOLATED ACTIVITY FADE AFTER SUNSET. FRONT CONTINUES TO DRIFT SOUTH OVRNGT WITH WEAK HIGH PRESSURE BUILDING ACROSS MS VLY/WRN LAKES. PATTERN REMAINS MUCH THE SAME SUNDAY...AND IN FACT FOR NEXT SVRL DAYS AS FCST AREA REMAINS IN TRANSITION ZONE BETWEEN UPPER RIDGE OVER RCKYS/HIGH PLAINS AND LARGE SCALE UPPER TROUGH OVER EASTERN NOAM. ANOTHER IN THIS SEEMINGLY ENDLESS PARADE OF S/WV DISTURBANCES ALREADY VISIBLE IN SAT PICS OVER NRN MANITOBA THIS AFTN...SLIDES SOUTHEAST TOWARD THE GRTLKS REGION IN ASSOCIATION WITH 100+ KT UPPER JET STREAK. WRF/GFS BOTH INDICATE WEAK SFC TROF ASSOCIATED WITH THIS FEATURE WHICH DROPS THROUGH WI BY LATE AFTN...WITH WEAK SFC HIGH PRESSURE RIDGE SLIDING OFF TO THE SOUTHEAST. THIS ALLOWS LGT VRBL WINDS TO BECOME SOUTH...WITH MODELS APPEARING TO AGAIN EXAGGERATE MOISTURE RETURN AHEAD OF TROF AND RESULTING INSTABILITY AND CONVECTIVE POTENTIAL ACROSS SRN WI/NRN IL BY EVE. BASED ON CURRENT TRENDS AND WEAKER LLVL MOIST ADVECTION WILL MAINTAIN DRY FCST SUNDAY. TEMPS EXPECTED TO BE SIMILAR TO TODAY...WITH 850 HPA TEMPS NEAR +15C...RANGING FROM LOW 80S NORTH TO MID/UPPER 80S SOUTH. GUIDANCE TEMPS SEEM TO RANGE QUITE A BIT...AND HAVE GENERALLY GONE IN BETWEEN MAV/MET NUMBERS BASED MORE ON 950/850 HPA TEMPS. WITH PATTERN AS NOTED ABOVE...WEAK LLVL BAROCLINIC ZONE/FRONTAL BOUNDARY SETS UP FROM NRN HIGH PLAINS/MT SOUTHEAST THROUGH SRN GRTLKS AND OH VALLEY THROUGH MID/LATE WEEK. MEDIUM RANGE GUIDANCE TRENDS CONTINUE TO SLOW BREAKDOWN/EASTWARD PROPAGATION OF EASTERN NOAM UPPER TROUGH...AND BUILDING UPPER RIDGE INTO MS VLY REGION. WITH SERIES OF LOW AMPLITUDE S/WVS ALLOWING FRONTAL POSITION TO VACILLATE ACROSS CWA...POTENTIAL FOR LARGE TEMP BUSTS EXISTS AS WELL AS LOW CONFIDENCE IN TIMING OF BETTER PERIODS OF PCPN POTENTIAL. SOME AGREEMENT WITH YET ANOTHER S/WV DROPPING ACROSS UPR MIDWEST/LAKES WITH WEAK SFC WAVE RIPPLING ALONG SFC TROF WHICH SETTLES ACROSS NRN IL/IND SUNDAY NIGHT. AGAIN CONFIDENCE ESPECIALLY WITH RESPECT TO TIMING REMAIN FAIRLY LOW...WHILE MODEL POPS SUPPORT INCLUDING AT LEAST A LOW CHC MENTION FOR MON AFTN INTO TUESDAY. WITH BOUNDARY SOUTH OF LAKE...AT LEAST WEAK LLVL NELY FLOW/LAKE INFLUENCE EXPECTED AND HAVE BACKED OF SIGNIFICANTLY WARMER TEMPS. MODEL TRENDS LATE IN PERIOD CONTINUE TO TRY TO BUILD RIDGE EAST...THOUGH EVEN CONSECUTIVE GFS RUNS INCONSISTENT WITH MEX GUIDANCE NUMBERS FOR KRFD 82 OFF 00Z RUN AND 94 OFF 12Z RUN. HAVE CONTINUED TO STAY CONSERVATIVE ALONG HPC GUIDANCE NUMBERS UNTIL TREND STABILIZES. RATZER && .AVIATION... 1220 AM CDT FOR THE 0600Z TAFS...QUIET WEATHER IS EXPECTED TO PREVAIL ACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA THROUGH THE FORECAST PERIOD. SURFACE COLD FRONT IS NOW WELL SOUTH OF THE TERMINALS AND EXTENDS FROM WEST CENTRAL ILLINOIS TO NEAR CMI AT 05Z. SCATTERED THUNDERSTORMS CONTINUE TO DEVELOP ALONG THIS FRONT...BUT ALL PRECIP WILL REMAIN SOUTH OF THE TERMINALS THROUGH THE OVERNIGHT. SURFACE OBS/KLOT WSR-88D DATA DID PICK UP ON BOUNDARY TRACKING SOUTHWEST FROM LAKE MICHIGAN WHICH ALLOWED FOR A WIND SHIFT TO THE NORTHEAST FROM 040-060 DEGREES. INITIALLY SOME GUSTS UP TO 15 KNOTS WITH THIS WIND SHIFT LINE...BUT LATEST OBSERVATIONS INDICATE THAT GUSTS ARE BEGINNING TO SUBSIDE. WINDS SHOULD GO LIGHT AND VARIABLE OR CALM BY 09Z. ON SUNDAY...DRIER LOW LEVEL AIR WILL BE PLACE ACROSS THE AREA SO ANY AFTERNOON CU SHOULD BE RELATIVELY HIGH BASED AOA 5K FT. SFC PRESSURE GRADIENT WILL BE QUITE WEAK ACROSS THE SOUTHERN GREAT LAKES TODAY...ALTHOUGH COMBINATION OF DEPARTING SFC RIDGE AXIS AND A VERY WEAK SFC LOW ACROSS WI SHOULD MAINTAIN A WESTERLY GRADIENT. A WEAK LAKE BREEZE SHOULD FORM DESPITE RATHER MARGINAL LAKE/LAND TEMPERATURE DIFFERENCES AND WILL MAINTAIN IDEA OF PREVIOUS FORECAST IN NOT BRINGING THIS LAKE BREEZE AS FAR WEST AS ORD/MDW. WILL KEEP WEST WINDS 5 TO 10 KNOTS ACROSS RFD/DPA THIS AFTERNOON WITH WINDS GOING LIGHT AND VARIABLE AT ORD/MDW. MARSILI && .MARINE... 214 PM...SFC COLD FRONT PUSHING SOUTHEAST ACROSS SOUTHERN LAKE MICHIGAN THIS AFTERNOON AS SFC LOW MOVES EAST ACROSS THE NORTHERN LAKES. SFC FRONT REACHES THE OHIO VALLEY OVERNIGHT AS WEAK HIGH PRESSURE BUILDS ACROSS THE LAKES REGION LATE TONIGHT AND SUNDAY. WESTERLY FLOW 15-25KTS WILL TURN NORTHERLY THIS EVENING AND BEGIN TO DECREASE THRU THE EVENING TURNING LIGHT SOUTHERLY SUNDAY MORNING THEN AS THE HIGH BUILDS ACROSS THE REGION...FLOW BECOMES SOMEWHAT LIGHTER BY SUNDAY EVENING...THOUGH STILL SOUTHERLY. CONFIDENCE IN THE FORECAST DECLINES SUNDAY NIGHT INTO MONDAY AS MODELS DEVELOP ANOTHER FRONTAL BOUNDARY BUT POSITION/TIMING MAY RESULT IN SOME MAJOR DIFFERENCES IN WIND DIRECTION MONDAY. APPEARS WINDS WILL TURN NORTHEASTERLY ACROSS NORTHERN LAKE MICHIGAN MONDAY MORNING THEN ACROSS THE ENTIRE LAKE BY MONDAY EVENING AND HAVE FOLLOWED THIS TREND. WITH A WEAK HIGH ACROSS THE LAKES TUESDAY AND FRONT REMAINING SOUTH OF THE LAKES...SHOULD MAINTAIN SOME TYPE OF LIGHT EASTERLY FLOW INTO TUESDAY NIGHT. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS RENO NV
100 AM PDT TUE JUL 17 2007 .UPDATE... SOME LIGHT SHOWERS ARE DEVELOPING NEAR MINDEN EARLY THIS MORNING AHEAD OF SHORT WAVE. STILL ENOUGH MID-LEVEL MOISTURE TO PRODUCE SOME LIGHT SHOWERS AND WILL ADD TO RENO ZONE THROUGH ABOUT SUNRISE AND CONTINUE MENTION EAST. DO NOT EXPECT THUNDERSTORMS AS INSTABILITY IS WEAK BUT A STRAY STRIKE OR TWO MAY STILL OCCUR. WALLMAN && .PREV UPDATE...ISSUED AT 905 PM A BUSY SWING SHIFT BETWEEN SEVERE THUNDERSTORMS AND FIRE WEATHER CONCERNS! CONVECTION IS GENERALLY WINDING DOWN WITH LOSS OF DAYTIME HEATING. EARLIER WE HAD REPORTS OF WIND DAMAGE NEAR FALLON ASSOCIATED WITH A SMALL LINE SEGMENT MOVING THROUGH WESTERN CHURCHILL COUNTY. TRAINING CELLS OVER PORTIONS OF MINERAL AND SOUTHERN LYON COUNTY LIKELY PRODUCED AT LEAST 1.5 INCHES OF RAIN BASED ON CALIBRATED RADAR ESTIMATES. WILL CONTINUE SLT CHCS OF -SHRA OVERNIGHT IN CAZ073 INTO NVZ001/004 WITH SHORTWAVE LIFTING NORTH INTO THE REGION COUPLED WITH REASONABLY MOIST AIRMASS. SOME ISLTD -SHRA HAVE RECENTLY DEVELOPED JUST EAST OF US 395 IN MONO COUNTY. PRIMARY FOCUS TONIGHT WILL BE DEALING WITH AREAS OF SMOKE... ESPECIALLY IN THE RENO METRO ASSOC WITH HAWKINS FIRE. WESTERLY LOW LEVEL WINDS ARE PUSHING A PLUME OF SMOKE ACROSS SRN SECTIONS OF THE CITY. BUT RECENT AIRCRAFT/MDCRS WIND REPORTS SHOWING SLY FLOW AOA 10KFT MSL...AND WE`RE ALSO SEEING SOME SMOKE DRIFT NORTHWARD ONCE IT HITS A HIGH ENOUGH ALTITUDE. WE ARE EXPECTING SMOKE TO SETTLE AND SPREAD OUT OVERNIGHT AS WINDS LIGHTEN BUT HIGHER ALTITUDE WINDS WILL LIKELY REMAIN UP OVERNIGHT AS SHORTWAVE MOVES THROUGH. WILL ADD AREAS OF SMOKE TONIGHT INTO EARLY TUESDAY MORNING TO THE FCST FOR THE RENO-SPARKS VICINITY AND OVER A SMALL PART OF MONO COUNTY NEAR THE CONWAY FIRE. HAVE ISSUED AN SPS FOR RESTRICTED VSBYS IN THE VICINITY OF RENO. WILL NEED TO EVALUATE LATER WHETHER A DENSE SMOKE ADVISORY IS WARRANTED. WILL LOWER TEMPS A COUPLE DEGREES IN THE ERN ZONES WHERE RAIN COOLED AIRMASS EXISTS. REST OF FCST UNCHANGED. UPDATE OUT BY 930 PM PDT. CS && .SHORT TERM... UPPER TROUGH CONTINUES TO APPROACH THE WEST COAST WITH S/W OVER THE SOUTHWEST U.S. BEGINNING TO EJECT NORTHEASTWARD TOWARD NEVADA. CUMULUS DEVELOPMENT HAS BEEN SLOW AND DISORGANIZED THUS FAR BASED ON AREA WEBCAMS WITH MOST OF THE CONVECTION THROUGH EARLY AFTERNOON RESIDING OVER THE NORTHEAST CORNER OF THE STATE. AS UPPER JET MOVES CLOSER GENERAL LARGE SCALE LIFT SHOULD INCREASE AND HELP TO FOCUS THUNDERSTORM DEVELOPMENT IN AREAS OF INSTABILITY. THE BEST COVERAGE WILL BE ALONG THE CONVERGENCE ZONE (MONO-MINERAL-EASTERN CHURCHILL COUNTIES) WITH MORE ISOLATED CELLS EXTENDING WESTWARD TO ALPINE COUNTY AND UP THE PINE NUT/VIRGINIA RANGES. CONVECTION MAY LINGER PAST MIDNIGHT SO ISOLATED POPS WERE MAINTAINED EASTERN ZONES. SOUTHWEST FLOW WILL INCREASE TUESDAY AND ESPECIALLY WEDNESDAY WITH PASSAGE OF COLD FRONT. LAKE WIND ADVISORIES WILL BE RAISED NORTHWEST AREAS TUESDAY AND WILL BE NEEDED MANY AREAS FOR WEDNESDAY. SEE FIRE DISCUSSION BELOW FOR FURTHER IMPACTS FROM THE WIND. THERE IS STILL SOME SUGGESTION THAT JET SUPPORT MAY BE SUFFICIENT TO PRODUCE SHOWERS ACROSS THE NORTHERN HALF OF AREA LATE WEDNESDAY. OTHERWISE COOLER TEMPERATURES ON TAP FOR WEDNESDAY WITH ONLY SLIGHT MODERATION THURSDAY AS TEMPERATURES HANG NEAR OR SLIGHTLY BELOW NORMAL. HOHMANN .LONG TERM...FRIDAY THROUGH MONDAY... RIDGE REBUILDS OVER THE FOUR CORNERS REGION WITH WARMER AIR MASS RETURNING TO WRN NV-ERN CA. MAX TEMPS LIKELY TO JUMP 8-10 DEGREES IN COMPARISON TO THURS AS 700 MB TEMPS RISE ABOUT 4 DEGREES C WITH NO CLOUD COVER. FURTHER WARMING IS LIKELY SATURDAY AS RIDGE STRENGTHENS OVER THE NRN-CNTRL ROCKIES AND EXPANDS IN EAST-WEST COVERAGE. MAX TEMPS WILL GET CLOSE TO 100 IN MOST WRN NV VALLEYS WITH LOWER 100S IN W-CNTRL NV. BY SUN-MON...THE GFS AND ECMWF BEGIN TO OFFER DIVERGING SOLUTIONS. THE GFS BUILDS THE RIDGE FARTHER NORTH WITH 600 DM CENTER IN MONTANA WHICH ALLOWS MONSOON MOISTURE TO SPREAD NORTH INTO CENTRAL NV-CA WHILE THE ECMWF BRINGS NEXT TROF TOWARD THE WEST COAST. THE CONTRASTS INCREASE ON MONDAY AS THE ECMWF DROPS 500 MB HEIGHTS BACK TO 585 DM WITH INCREASE IN STABLE SW FLOW...BUT GFS KEEPS HEIGHTS IN THE LOW 590S WHILE SPREADING MONSOON MOISTURE AND INSTBY ACROSS ALL OF THE FORECAST AREA. FOR THIS TIME OF YEAR...IT IS REASONABLE TO EXPECT THE MONSOON TO MAKE SOME NORTHWARD PROGRESS AND ALSO CONSIDERING THE EXPECTED STRENGTH OF THE RIDGE...THE NEXT APPROACHING TROF WILL HAVE A TOUGH TIME BREAKING IT DOWN QUICKLY. EVENTUAL WEAKENING OF THE RIDGE SHOULD OCCUR TOWARD THE MIDDLE OF NEXT WEEK...BUT UNTIL THEN ANOTHER 100 DEGREE DAY IS LIKELY IN THE VALLEYS ON SUNDAY WITH ONLY A SLIGHT DROP IN MAX TEMPS MONDAY DUE TO INCREASED CLOUD COVER AND POTENTIAL FOR TSTMS. THE PRESENCE OF MORE CLOUDS ALSO REQUIRED RAISING MIN TEMPS A FEW DEGREES STARTING SUN NIGHT. THE THREAT OF TSTMS WAS LIMITED TO AREAS SOUTH OF HIGHWAY 50 IN NV AND ALONG THE SIERRA CREST FROM TAHOE SOUTHWARD ON SUNDAY...THEN EXPANDED TO THE REMAINDER OF THE REGION FOR MONDAY. MJD && .AVIATION... ISOLD TO SCT -TSRA WITH BRIEF MVFR CONDS SOUTH AND EAST OF A KTVL-KLOL LINE THRU 04Z...WITH ISOLD -TSRA EAST OF HWY 95 OVERNIGHT. OTHERWISE VFR THRU TUESDAY WITH SW-W ZEPHYR WIND GUSTS TO 25 KT THRU 04Z THIS EVENING AND 25-30 KT GUSTS TUESDAY BTWN 22Z-04Z MJD && .FIRE WEATHER... ISOLATED TO SCATTERED THUNDERSTORMS MAINLY OVER MINERAL AND SRN LYON COUNTY WILL MOVE NORTHEAST 10-15 MPH. THESE THUNDERSTORMS WILL LIKELY SPARK SOME FIRES OUTSIDE OF THE WET CORES...HOWEVER THUNDERSTORMS WILL DEVELOP AND MOVE OVER THE SAME AREAS SO THERE IS A GOOD CHANCE THESE NEW FIRE STARTS MAY GET SOME RAIN OVER THEM THIS AFTERNOON. THE NEXT MAIN CONCERN WILL THE BE THE WIND AHEAD OF A COLD FRONT MOVING IN FROM THE PACIFIC. WINDS WILL STILL BE GUSTY TODAY...GENERALLY 25-30 MPH IN MOST AREAS WEST OF HIGHWAY 395. BY TOMORROW WINDS WILL REALLY PICK UP NORTH OF INTERSTATE 80 WHILE CONDITIONS REMAIN CRITICALLY DRY. GRADIENTS TIGHTEN AND 700 MB FLOW STARTS TO INCREASE TO 20-25KTS. THEREFORE RED FLAG WARNINGS WERE ISSUED FOR ZONES 272/271/278/270 AND 450/458. AREAS SOUTH AND EAST WILL SEE WIND GUSTS IN THE 25-30 MPH RANGE ON TUESDAY. BY WEDNESDAY THE FRONT MOVES CLOSER WITH A MUCH TIGHTER SURFACE GRADIENT AND 700 MB FLOW INCREASING TO 25-35 KTS. FIRE WEATHER WATCHES WERE ISSUED FOR NV ZONES 450/453/459 AND CA ZONE 273 FOR WEDNESDAY. THE MAIN QUESTION IN TAHOE AND AREAS NORTH WILL BE RH RECOVERY AND INCREASE. MOISTURE WILL MOVE IN AHEAD OF THE FRONT WITH INCREASING HUMIDITIES...HOWEVER ZONE 458 AND THE TAHOE BASIN WILL NEED TO BE WATCHED AS STRONG DOWNSLOPE WINDS IN 458 MAY COUNTERACT THE HUMIDITY INCREASE AND STILL DRY THINGS OUT. THE TAHOE BASIN MIGHT BE JUST FAR SOUTH ENOUGH TO NOT SEE THE HUMIDITY INCREASES THAT WILL MAKE MUCH DIFFERENCE. MID SHIFT CAN TAKE A LOOK AND ADD THOSE AREAS TO THE WATCH IF NEED BE. BENINATO .REV WATCHES/WARNINGS/ADVISORIES... NV...RED FLAG WARNING FROM 1 PM TO 9 PM PDT TUESDAY FOR NVZ450-458. FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY EVENING FOR NVZ450-453-459. CA...RED FLAG WARNING FROM 1 PM TO 9 PM PDT TUESDAY FOR CAZ270>272- 278. FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY EVENING FOR CAZ273. && $$ HTTP://WEATHER.GOV/RENO
AREA FORECAST DISCUSSION
NWS MISSOULA MT
329 AM MDT TUE JUL 17 2007 .DISCUSSION...A DEEP LOW PRESSURE SYSTEM DRIFTING CLOSER TO THE OREGON COAST HAS BEGUN TO PUMP SUB-TROPICAL MOISTURE NORTHWARD TOWARDS THE NORTHERN ROCKIES REGION. SATELLITE IMAGERY CLEARLY SHOWS A DISTURBANCE MAKING ITS WAY NORTH THROUGH NORTHEAST NEVADA/SOUTHERN IDAHO EARLY THIS MORNING. THE AIR MASS REMAINS WARM AND UNSTABLE WITH THE BIGGEST CHANGE FOCUSED AROUND INCREASED MOISTURE...EXPANDING THE SHOWER/THUNDERSTORM POTENTIAL THROUGHOUT NORTH-CENTRAL IDAHO AND WESTERN MONTANA. INCREASED CLOUD COVER AND SHOWERS WILL HELP HOLD TEMPERATURES DOWN IN INTO THE UPPER 80S AND 90S IN MOST LOCATIONS. NORTHWEST MONTANA WILL SEE SOME OF THE WARMER TEMPERATURES DUE TO THE LATER ARRIVAL OF CLOUDS AND SHOWERS. CONVECTION WILL CONTINUE INTO THE EVENING HOURS BEFORE TAPERING OFF AFTER MIDNIGHT. WEDNESDAY AND WEDNESDAY NIGHT...THE MODELS HAVE BEEN CONSISTENT WILL THE STRENGTHENING OF THE UPPER RIDGE AND MIGRATION OF DRIER AIR INTO THE AREA FROM THE SOUTH. SKIES ARE EXPECTED TO CLEAR BY MORNING. THE AIR MASS WILL REMAIN VERY WARM AND QUITE UNSTABLE. THUS...AFTERNOON BUILDUPS AND ISOLATED LATE-DAY THUNDERSTORMS ARE STILL IN THE FORECAST PICTURE...MAINLY ALONG THE CONTINENTAL DIVIDE AND NORTHWEST MONTANA. THURSDAY...THE AFOREMENTIONED LOW SYSTEM OFF THE OREGON COAST WILL KICK INLAND OVER THE PACIFIC NORTHWEST AS AN OPEN TROUGH AND SWEEP NORTHWARD BRUSHING BY OUR WESTERN ZONES. THIS WILL EFFECTIVELY SHOVE THE INVERTED SURFACE TROUGH ACROSS WESTERN MONTANA LATER IN THE DAY. THE COMBINATION OF WINDS ALOFT MIXING THE SURFACE AND AN INCREASED SURFACE PRESSURE GRADIENT WILL RESULT IN INCREASED WINDS. WINDS COUPLED WITH EXISTING HOT DRY CONDITIONS WILL RAISE FIRE WEATHER CONCERNS...ESPECIALLY AFTER A CONVECTIVELY ACTIVE PERIOD. THURSDAY NIGHT THROUGH MONDAY...AS THE SYSTEM MOVES QUICKLY TO THE NORTH INTO CANADA A STRONG SURFACE PRESSURE GRADIENT WILL KEEP BREEZY CONDITIONS INTO THE EVENING HOURS THURSDAY. THE HIGH PRESSURE RIDGE WILL BEGIN TO PUSH BACK TO THE NORTH AND ALLOW FOR ANOTHER WARMING TREND THROUGH THE WEEKEND. TEMPERATURES ARE EXPECTED TO BE NEAR THE CENTURY MARK AGAIN ON SATURDAY AND SUNDAY. FRIDAY SHOULD BE MOSTLY SUNNY AND DRY. ON SATURDAY A WAVE OF ENERGY WILL PASS THROUGH AND COUPLED WITH A RELATIVE INCREASE IN MOISTURE WILL BRING CHANCES FOR SHOWERS AND THUNDERSTORMS PARTICULARLY ALONG THE CONTINENTAL DIVIDE DURING THE AFTERNOON. A SIMILAR SETUP WILL FORM ON SUNDAY AND MONDAY AFTERNOONS AS WELL AND SLIGHT CHANCES FOR THUNDERSTORMS ARE EXPECTED AGAIN ALONG THE DIVIDE. && .AVIATION...WIDELY SCATTERED SHOWERS CONTINUE IN SOUTHWEST MONTANA THIS MORNING BUT WILL BE MOVING OUT OF THE AREA SHORTLY AFTER SUNRISE. AIRCRAFT FLYING THROUGH THIS AREA AND AROUND THE KBTM TERMINAL SHOULD BE AWARE OF POTENTIAL GUSTY WINDS ASSOCIATED WITH THESE STORM CELLS THIS MORNING. THIS AFTERNOON ANOTHER STORM SYSTEM PUSHES THROUGH AND WILL CAUSE WIDESPREAD CONVECTION WITH ELEVATED POTENTIAL FOR GUSTY WINDS AND TURBULENCE LATE MORNING THROUGH THIS EVENING THROUGHOUT WESTERN MONTANA AND NORTH CENTRAL IDAHO...SEE APPROPRIATE TAFS AND TWEBS. && .FIRE WEATHER...THUNDERSTORMS ACTIVITY WILL INCREASE TODAY AS WELL EXPAND INTO NORTHWEST MONTANA. THE AIR MASS IS EXPECTED TO DRY AND WARM...THUS RETURNING TEMPERATURE READINGS BACK TOWARDS NEAR RECORD LEVELS ON WEDNESDAY. THURSDAY...THERE IS A GROWING CONCERN THAT A COMBINATION OF INCREASED WINDS...HOT DRY CONDITIONS AND EVEN A POTENTIAL OF ISOLATED LATE AFTERNOON THUNDERSTORMS WILL PROVIDE AN ACTIVE BURNING PERIOD. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...NONE. ID...NONE. && $$ SHORT TERM...MSJ LONG TERM....FOSTER AVIATION...FOSTER
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
1030 AM CDT TUE JUL 17 2007 .UPDATED DISCUSSION 1030AM...EBBING MCS MOVING THROUGH CENTRAL ILL WITH STRATOFORM RAIN AREA MAINLY CHI SWD. AIRMASS HAS STABILIZED NOW AND TEMPS WILL RISE SLOWLY UNDER PERSISTENT CLOUD COVER. AS CLOUDS THIN TEMPS WILL PUSH THROUGH THE 70S BUT ACARS DATA SUGGESTS NEAR 80 WILL BE ABOUT IT MOST PLACES. HAVE TRIMMED BACK MAX TEMPS TDA TO REFLECT CONDS. OVERALL PATTERN STILL FAVORS ADDITIONAL TSTMS CLUSTER DEVELOPMENT UPSTREAM LATER TODAY AND EARLY TONIGHT. A BIT DIFFICULT TO PIN POINT WHERE THIS WILL OCCUR NOW BUT THAT MAY BECOME MORE EVIDENT LATER TODAY. CURRENT FLOOD WATCH WILL BE CONTD ALTHOUGH PRIME TIME OF CONCERN IS TONIGHT IN EARLY WED. IF TEMPS APPROACH 80 A FEW SHOWERS OR TSTMS COULD BUILD SO POPS THIS AFTN WILL BE HELD IN CHC CATAGORY. THIS PATTERN WILL BREAK BY FRIDAY AS HIGH PRESSURE BUILDS SWD INTO REGION BUT THE THREAT FOR LOCAL R+ MAY PERSIST INTO THURSDAY. KML PREVIOUS DISCUSSION...FOCUS CONTINUES TO BE ON THREAT OF REPEATED ROUNDS OF THUNDERSTORMS UNTIL CFP LATE WED NIGHT AND POTENTIAL FOR HEAVY RAINFALL PRODUCTION. MCS THAT WAS OVER NORTH CENTRAL IA EARLY MON EVE HAS CONTINUED TO MOVE SOUTHEAST WITH MEAN MID LEVEL FLOW AND ALONG THE SFC BOUNDARY THROUGH THE NIGHT. MCS CURRENTLY INTO EAST CENTRAL IL AND EXTRAPOLATION PUTS VORT CENTER ON THE IND BORDER BY 11Z WITH LINGERING -SHRA IN NW IND COUNTIES OF FA ENDING QUICKLY THEREAFTER. A LITTLE FURTHER NORTH MORE TSRA DEVELOPED OVERNIGHT FM SOUTHEAST MN INTO NORTHEAST IA AND FM SOUTHEAST WI INTO SOUTHWEST LOWER MI. THIS ACTIVITY RIGHT ALONG AXIS OF WHERE MODELS INDICATING QG FRONTOGENESIS OCCURRING. THIS AXIS IS FORECAST BY MODELS TO LIE FM SOUTHWEST WI ACROSS FAR NORTH CENTRAL IL AND FAR SOUTHERN LK MI AT 18Z THEN SHIFT A BIT NORTHWARD BY 00Z WED. MODELS INDICATED THAT LOWER LEVEL WINDS WOULD VEER TO MORE WESTERLY OVERNIGHT AND PROFILER AND VAD WINDS TO THE WEST SHOW THAT THIS IS VERIFYING SO ACTIVITY APPROACHING FROM NORTHEAST IA EXPECTED TO WANE SOMEWHAT AS IT MOVES INTO NORTHERN IL LATER THIS MORNING. WATER VAPOR SATELLITE SHOWS A FAST MOVING SPEED MAX/SHORT WAVE DROPPING SOUTHEASTWARD FM FAR SOUTHERN MANITOBA INTO FAR NORTHWEST MN. TRACKING ACROSS THE UPPER MIDWEST IT SHOULD BE APPROACHING NORTHERN IL BY LATE MORNING. WITH STRONGER WAA IN LOWER LEVELS THAN MID LEVELS LAPSE RATES HAVE STEEPENED A BIT. EXPECT A BREAK IN CLOUDS LATER THIS MORNING AFTER NORTHEAST IA TSRA PASS BY. THIS TO ALLOW A PERIOD OF SURFACE HEATING AHEAD OF SHORT WAVE DROPPING ACROSS THE UPPER MIDWEST AND EXPECT MORE TSRA DEVELOPMENT ACROSS THE AREA. 00Z RAOBS MEASURED AROUND 1.5 INCHES OF PRECIPITABLE WATER IN THE AIRMASS AND SATELLITE SOUNDER ESTIMATES SIMILAR. WHILE BULK OF OVERNIGHT MCS MOVES INTO CENTRAL IL AND DID NOT DEPOSIT LARGE AMOUNTS OF WATER IN THE FA THE NEXT AREA OF TSRA EXPECTED TO TRACK A BIT FURTHER NORTH AS EFFECTIVE SFC BOUNDARY APPEARS TO HAVE SHIFTED INTO NORTHERN IL. AS MENTIONED ABOVE THIS AREA EXPECTED TO DECREASE IN INTENSITY WITH TIME THIS MORNING BUT WITH RENEWED DEVELOPMENT FROM UPSTREAM SHORT WAVE THERE STILL EXISTS THE POTENTIAL FOR AREAS OF HEAVY RAINFALL SO WATCH MAINTAINED AND EXTENDED THROUGH THE NIGHT AS MODELS DEPICTING AXIS OF QPF STILL ACROSS NORTH CENTRAL AND NORTHEAST IL INTO NORTHWEST IND DURING 06Z-12Z WED TIME FRAME. MODEL SOLUTIONS DIFFER ON WHERE BOUNDARY ENDS UP FOR DAYTIME WED WITH SOLUTIONS ACROSS NORTHERN IL OR SOUTHERN WI SO CONTINUED CHANCES OF TSRA FOR WED. BOUNDARY TO BE CLEARED OUT OF AREA BY LATER THU AS STRONG UPPER WAVE CURRENTLY IN FAR NORTH CENTRAL CANADA EVENTUALLY DROPS SOUTHEAST ACROSS WESTERN ONTARIO AND THROUGH THE GREAT LAKES ESCORTING A LARGE SURFACE ANTICYCLONE INTO THE UPPER MIDWEST AND WESTERN GREAT LAKES THU NIGHT AND FRI. HIGH PRES REMAINS ACROSS THE GREAT LAKES INTO THE WEEKEND WITH DRY WX AND COMFORTABLE TEMPS AND DEW POINTS. TRS && .AVIATION DISCUSSION REGARDING 00Z TAFS... 639 AM CDT THERE IS ANOTHER MESOSCALE CONVECTIVE SYSTEM MOVING ACROSS NORTH CENTRAL ILLINOIS AT 1130 UTC. THIS IS SEEN ON THE SATELLITE IR IMAGE. USING THE WRF 40 KM MODEL AND THE WATER VAPOR WE SEE THAT THE MCS LINES UP WITH VORTICITY MAXIMUM AT 500 MB. THE NEXT VORTICITY MAXIMUM MOVE INTO THE REGION AROUND 18 UTC AND THEN A THIRD MOVES THROUGH AROUND 09 UTC. WILL PUT THE THUNDERSTORMS IN THE FORECASTS AT THOSE TIMES. THESE VORTICITY MAXIMUMS ARE SEEN ON THE WATER VAPOR IMAGERY EXTENDING AS FAR NORTHWEST AS MANITOBA. THE LONG WAVE TROUGH WILL BE SLOW MOVING IN THE EASTERN NORTH AMERICA. THE TAF AREA WILL BE IN NORTHWEST FLOW FOR THE NEXT 24 HOURS. THE FRONT WILL MOVE THROUGH TOWARDS WISCONSIN THIS AFTERNOON. WE EXPECT THE WIND WILL BECOME SOUTH THIS EVENING. && .MARINE DISCUSSION... 229 AM CDT A STATIONARY FRONT WILL BECOME A WARM FRONT TONIGHT AND MOVE NORTH TO THE ILLINOIS WISCONSIN BORDER. WE WILL USE THE GFS MODEL FOR BEYOND 36 HOURS AND WRF MODEL FOR NOW TO 36 HOURS FOR THE WIND FORECAST. THE WIND WILL BE LIGHT TODAY AND WEDNESDAY AS A LOW DEVELOPS ALONG THE FRONT IN IOWA AND MOVES INTO ILLINOIS BY WEDNESDAY EVENING. BY THURSDAY MORNING THE WIND WILL BE FROM THE NORTH OVER THE NORTHERN TWO THIRDS OF LAKE MICHIGAN. && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FA.A TIL 11Z 0718 IN...FA.A TIL 11Z 0718 LM...NONE &&
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1030 AM EDT TUE JUL 17 2007 .MORNING UPDATE... A CHALLENGING FORECAST IN TERMS OF HOW AFTERNOON CONVECTION WILL EVOLVE. MORNING FORECAST AND ACARS SOUNDINGS SHOW WEAKLY UNSTABLE LAPSE RATES WITH LITTLE OR NO CAP. THERE SHOULD BE LITTLE INHIBITION TO CONVECTION LATER TODAY. THE PROBLEM RESIDES IN THE THE INITIAL TRIGGERING OF STORMS IN THE FIRST PLACE. PRECIPITATION FROM THE REMNENTS OF AN EARLIER MCS ACROSS INDIANA IS ERODING AS IT APPROACHES OUR CWA ACROSS SOUTHERN INDIANA. IS POSSIBLE THAT SOME LIGHT SHOWERS WILL MAKE IT INTO OUR NORTHERN TIER OF COUNTIES BY LATE MORNING. INITIALLY...THESE SHOWERS WILL BE QUITE LIGHT...BUT HAVE AMENDED FORECAST TO INCREASE POPS TO 50% ACROSS OUR NORTH. INCREASED CLOUDINESS WILL LOWER HIGHS ACROSS THE NORTH INTO THE MID 80S. CONVECTIVE INITIATION THIS AFTERNOON MAY OCCUR IN TWO LOCATIONS. THE FIRST MAY BEGIN ACROSS OUR SOUTHEASTERN COUNTIES AND THE HIGHER TERRAIN OF EASTERN KENTUCKY. DEEPER MOISTURE RESIDES THERE...AND THERE HAS BEEN SOME RECENT MID-LEVEL CU DEVELOPMENT. THE OTHER MAY INVOLVE SOME SORT OF A BOUNDARY LEFT BY THE DECAYING MCS. HAVE AMENDED FORECAST TO MENTION SCATTERED CONVECTION THIS AFTERNOON. JSD .SHORT TERM (TODAY AND TONIGHT)... A BROAD UPPER LEVEL TROUGH WILL REMAIN PARKED ACROSS THE GREAT LAKES AND UPPER OHIO VALLEY FOR THIS FORECAST PERIOD. WE WILL SEE RISING HEIGHTS TODAY (WARMER TEMPERATURES) AS A JET MAX MOVES UP THE EAST SIDE OF THE TROUGH. THE SHORT RANGE MODELS ARE IN GOOD AGREEMENT ON THE LARGE SCALE SYNOPTIC PATTERN BUT DIFFER ON SHORT WAVE ENERGY MOVING THROUGH THE UPPER LEVEL FLOW. 00Z BUFKIT SOUNDINGS INDICATE A MARGINALLY UNSTABLE LATE AFTERNOON ATMOSPHERE SO I DON`T SEE ANY AREA WHERE THUNDERSTORMS WILL BE MORE LIKELY THAN OTHERS SO WE WILL GO WITH LOW CHANCE POPS THIS AFTERNOON ACROSS ALL THE FORECAST AREA. WE WILL HOLD ONTO LOW CHANCE OR ISOLATED POPS TONIGHT OVER THE NORTH... CLOSER TO A STATIONARY FRONT LOCATED ACROSS CENTRAL ILLINOIS AND INDIANA. CONVECTIVE COMPLEX MOVING THROUGH CENTRAL AND NORTHERN ILLINOIS THIS MORNING SHOULD REMAIN NORTH OF THE FORECAST AREA BASED ON MID LEVEL FLOW FORECASTS. --JA .LONG TERM (WEDNESDAY THROUGH MONDAY)... SOME MODEL DIFFERENCES IN PRECIP TIMING AND LOCATION...SO FOLLOWED A BLEND OF THE ENSEMBLES AND OPERATIONAL GFS FOR THE EXTENDED. WEDNESDAY-THURSDAY... THE ROCKY MOUNTAIN RIDGE AND HUDSON BAY TROUGH PATTERN AMPLIFIES DURING THIS TIME FRAME...PUTTING THE CWA UNDER A GOOD NWRLY FLOW ALOFT. A QUASI-STATIONARY FRONT EXTENDS EASTWARD FROM LOW PRESSURE OVER THE DAKOTAS...AND THIS BOUNDARY WILL COME INCREASING CLOSER DURING THIS TIME FRAME. WITH A SFC HIGH OFF THE SERN CONUS...GULF MOISTURE WILL POOL NORTHWARD AND PULSE CONVECTION SHOULD BE THE RULE WEDNESDAY AFTN-EVE AND PERHAPS AGAIN ON THURSDAY. GIVEN THE PRECIP COVERAGE OVER THE PAST COUPLE OF DAYS...BUMPED UP POPS TO 40 FOR THE BEST CHANCE OF PRECIP. SINCE NO FORCING MECHANISM IS AROUND WED...WENT WITH HIGHEST POPS OVER THE EAST. FOR THURSDAY...WENT WITH THE HIGHEST POPS NORTH CLOSER TO APPROACHING COLD FRONT. MOST OF THE PRECIP WILL BE DIURNAL...HOWEVER UNDER THE NW FLOW...MAY HAVE AN MCS DIVE SEWD TOWARD THE REGION EARLY WED MORNING. BEST CHANCE OF THIS WOULD BE ACROSS OUR INDIANA COUNTIES AND NRN BLUEGRASS COUNTIES WITH DAMAGING WINDS BEING POSSIBLE IF IT REACHES THE CWA. TEMPS DURING THIS PERIOD WILL BE HOT...WITH LOW 90S POSSIBLE FOR HIGHS BOTH DAYS...AND THE OVERNIGHT PERIODS FEELING MUGGY WITH LOWS AROUND 70 AND DEWPOINTS IN THE 60S. GUSTY SOUTHWEST WINDS WILL BE POSSIBLE ON THURSDAY AHEAD OF THE FRONT. THURSDAY NIGHT-FRIDAY NIGHT... BY THURSDAY EVENING...THE COLD FRONT SHOULD BE NEARING OUR NRN CWA BORDER. WITH HIGH LIKELY POPS IN THE MEX GUIDANCE...AND LOW LIKELY POPS IN THE ENSEMBLES...BUMPED UP POPS THURSDAY NIGHT TO LOW LIKELY POPS. NAM IS MUCH SLOWER ON FRONTAL BOUNDARY MOVEMENT...SO DELAYED THE FROPA A BIT...BUT STILL TRENDED TOWARD THE FASTER GFS...WHICH HAS THE FRONT THROUGH AND ALL PRECIP ENDING BY FRIDAY EVENING. SOME OF THE STORMS WITH THE FRONT COULD BE STRONG-SEVERE WITH MORE DYNAMICS INVOLVED. ALSO BUMPED UP POPS ON FRIDAY TO HIGH CHANCE SOUTH...AND JUST A SLIGHT CHANCE NORTH. HAVE ALL PRECIP ENDING BY 00Z SATURDAY. AL SATURDAY-MONDAY... SURFACE HIGH PRESSURE WILL DIVE SOUTH FROM THE GREAT LAKES LATE FRIDAY AND WILL DOMINATE THE REGION THRU EARLY NEXT WEEK...AS THE UPPER LEVEL TROUGH/CUT-OFF WILL START TO DRIFT OFF TO THE EAST BY MONDAY. TEMPS WILL BE BELOW NORMAL FRIDAY AND SATURDAY WITH THE NW FLOW...AND MUCH DRIER AIR WILL BE IN PLACE. A SLOW RETURN TO MORE SEASONAL DEWPOINTS AND TEMPS LATE INTO THE WEEKEND AND EARLY NEXT WEEK IS EXPECTED. SCHOTT && .AVIATION (12Z TAFS)... THE CONCERN THIS MORNING ARE THE BIG CONVECTIVE SYSTEMS DROPPING THROUGH IOWA AND ILLINOIS. THE MID LEVEL FLOW WOULD INDICATE THAT THEY WILL STAY JUST NORTH OF THE SDF AND LEX TAF SITES AND THIS IS HOW WE WILL PLAN THE CURRENT FORECASTS. WE EXPECT AFTERNOON CONVECTION TO BE 30% OR LESS AND AT THIS TIME WILL MENTION ONLY CB IN THE TAFS. --JA && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1250 PM CDT TUE JUL 17 2007 .UPDATE... 1030 AM CDT EBBING MCS MOVING THROUGH CENTRAL ILL WITH STRATIFORM RAIN AREA MAINLY CHI SWD. AIRMASS HAS STABILIZED NOW AND TEMPS WILL RISE SLOWLY UNDER PERSISTENT CLOUD COVER. AS CLOUDS THIN TEMPS WILL PUSH THROUGH THE 70S BUT ACARS DATA SUGGESTS NEAR 80 WILL BE ABOUT IT MOST PLACES. HAVE TRIMMED BACK MAX TEMPS TDA TO REFLECT CONDS. OVERALL PATTERN STILL FAVORS ADDITIONAL TSTMS CLUSTER DEVELOPMENT UPSTREAM LATER TODAY AND EARLY TONIGHT. A BIT DIFFICULT TO PIN POINT WHERE THIS WILL OCCUR NOW BUT THAT MAY BECOME MORE EVIDENT LATER TODAY. CURRENT FLOOD WATCH WILL BE CONTD ALTHOUGH PRIME TIME OF CONCERN IS TONIGHT IN EARLY WED. IF TEMPS APPROACH 80 A FEW SHOWERS OR TSTMS COULD BUILD SO POPS THIS AFTN WILL BE HELD IN CHC CATEGORY. THIS PATTERN WILL BREAK BY FRIDAY AS HIGH PRESSURE BUILDS SD INTO REGION BUT THE THREAT FOR LOCAL R+ MAY PERSIST INTO THURSDAY. KML && .PREV DISCUSSION... FOCUS CONTINUES TO BE ON THREAT OF REPEATED ROUNDS OF THUNDERSTORMS UNTIL CFP LATE WED NIGHT AND POTENTIAL FOR HEAVY RAINFALL PRODUCTION. MCS THAT WAS OVER NORTH CENTRAL IA EARLY MON EVE HAS CONTINUED TO MOVE SOUTHEAST WITH MEAN MID LEVEL FLOW AND ALONG THE SFC BOUNDARY THROUGH THE NIGHT. MCS CURRENTLY INTO EAST CENTRAL IL AND EXTRAPOLATION PUTS VORT CENTER ON THE IND BORDER BY 11Z WITH LINGERING -SHRA IN NW IND COUNTIES OF FA ENDING QUICKLY THEREAFTER. A LITTLE FURTHER NORTH MORE TSRA DEVELOPED OVERNIGHT FM SOUTHEAST MN INTO NORTHEAST IA AND FM SOUTHEAST WI INTO SOUTHWEST LOWER MI. THIS ACTIVITY RIGHT ALONG AXIS OF WHERE MODELS INDICATING QG FRONTOGENESIS OCCURRING. THIS AXIS IS FORECAST BY MODELS TO LIE FM SOUTHWEST WI ACROSS FAR NORTH CENTRAL IL AND FAR SOUTHERN LK MI AT 18Z THEN SHIFT A BIT NORTHWARD BY 00Z WED. MODELS INDICATED THAT LOWER LEVEL WINDS WOULD VEER TO MORE WESTERLY OVERNIGHT AND PROFILER AND VAD WINDS TO THE WEST SHOW THAT THIS IS VERIFYING SO ACTIVITY APPROACHING FROM NORTHEAST IA EXPECTED TO WANE SOMEWHAT AS IT MOVES INTO NORTHERN IL LATER THIS MORNING. WATER VAPOR SATELLITE SHOWS A FAST MOVING SPEED MAX/SHORT WAVE DROPPING SOUTHEASTWARD FM FAR SOUTHERN MANITOBA INTO FAR NORTHWEST MN. TRACKING ACROSS THE UPPER MIDWEST IT SHOULD BE APPROACHING NORTHERN IL BY LATE MORNING. WITH STRONGER WAA IN LOWER LEVELS THAN MID LEVELS LAPSE RATES HAVE STEEPENED A BIT. EXPECT A BREAK IN CLOUDS LATER THIS MORNING AFTER NORTHEAST IA TSRA PASS BY. THIS TO ALLOW A PERIOD OF SURFACE HEATING AHEAD OF SHORT WAVE DROPPING ACROSS THE UPPER MIDWEST AND EXPECT MORE TSRA DEVELOPMENT ACROSS THE AREA. 00Z RAOBS MEASURED AROUND 1.5 INCHES OF PRECIPITABLE WATER IN THE AIRMASS AND SATELLITE SOUNDER ESTIMATES SIMILAR. WHILE BULK OF OVERNIGHT MCS MOVES INTO CENTRAL IL AND DID NOT DEPOSIT LARGE AMOUNTS OF WATER IN THE FA THE NEXT AREA OF TSRA EXPECTED TO TRACK A BIT FURTHER NORTH AS EFFECTIVE SFC BOUNDARY APPEARS TO HAVE SHIFTED INTO NORTHERN IL. AS MENTIONED ABOVE THIS AREA EXPECTED TO DECREASE IN INTENSITY WITH TIME THIS MORNING BUT WITH RENEWED DEVELOPMENT FROM UPSTREAM SHORT WAVE THERE STILL EXISTS THE POTENTIAL FOR AREAS OF HEAVY RAINFALL SO WATCH MAINTAINED AND EXTENDED THROUGH THE NIGHT AS MODELS DEPICTING AXIS OF QPF STILL ACROSS NORTH CENTRAL AND NORTHEAST IL INTO NORTHWEST IND DURING 06Z-12Z WED TIME FRAME. MODEL SOLUTIONS DIFFER ON WHERE BOUNDARY ENDS UP FOR DAYTIME WED WITH SOLUTIONS ACROSS NORTHERN IL OR SOUTHERN WI SO CONTINUED CHANCES OF TSRA FOR WED. BOUNDARY TO BE CLEARED OUT OF AREA BY LATER THU AS STRONG UPPER WAVE CURRENTLY IN FAR NORTH CENTRAL CANADA EVENTUALLY DROPS SOUTHEAST ACROSS WESTERN ONTARIO AND THROUGH THE GREAT LAKES ESCORTING A LARGE SURFACE ANTICYCLONE INTO THE UPPER MIDWEST AND WESTERN GREAT LAKES THU NIGHT AND FRI. HIGH PRES REMAINS ACROSS THE GREAT LAKES INTO THE WEEKEND WITH DRY WX AND COMFORTABLE TEMPS AND DEW POINTS. TRS && .AVIATION... FOR THE 1800 UTC TAFS...FIRST 9 HOURS OR SO OF THIS TAF CYCLE APPEARS FAIRLY STRAIGHT FORWARD AS MCS THAT SKIRTED THE REGION THIS MORNING HAS LEFT CONDITIONS MORE STABLE WITH WEAK BUBBLE HIGH AT THE SURFACE LEADING A LARGELY DIVERGENT SURFACE FLOW. BY LATE EVENING OR MORE SO OVERNIGHT THE THREAT OF SHRA/TSRA WILL INCREASE AS CONVECTION THATS EXPECTED TO FIRE LATER THIS AFTERNOON IN/NEAR KFSD AREA CONSOLIDATES INTO ANOTHER MCS AND ROLLS ESE TOWARD THE AREA. CHANCE IS CERTAINLY THERE THAT TONIGHTS MCS COULD ONCE AGAIN SKIRT BY TO THE SW AND WITH THE WORST OF IT LARGELY MISSING THE TERMINALS. GIVEN THE INHERENT UNCERTAINTIES THIS FAR OUT DECIDED TO NOT LOWER CONDITIONS BELOW VFR AND TO JUST INTRODUCE VCTS OVERNIGHT AND THROUGH WED MORNING. ONCE STORMS DEVELOP THIS AFTERNOON...EVENING SHIFT MAY BE ABLE TO MAKE AN ATTEMPT AT BETTER PINPOINTING TIMING/LOCATION OF HIGHEST TSRA CHANCES IN SUBSEQUENT TAF ISSUANCE. IZZI && .MARINE... RELATIVELY LIGHT WINDS/WAVES EXPECTED ON THE LAKE THROUGH WEDNESDAY EVENING WITH WHAT WIND THERE IS GENERALLY FROM THE SOUTH OR SOUTHEAST. LATE WEDNESDAY NIGHT AND ESPECIALLY INTO THURSDAY LOOK FOR WINDS TO VEER TO THE NORTH AND BEGIN TO INCREASE AS A RATHER STRONG (AT LEAST FOR THIS TIME OF YEAR) CANADIAN HIGH BUILDS SOUTHWARD INTO THE UPPER MIDWEST. WINDS COULD POKE UP TO AROUND 30KT FOR A TIME THURSDAY...PARTICULARLY OVER THE SOUTH HALF OF THE LAKE WHERE WIND WILL HAVE A BASICALLY UNOBSTRUCTED PATH. MODERATELY STRONG NORTHERLY FLOW DOWN THE FULL FETCH OF THE LAKE SHOULD ALLOW WAVES TO BUILD TO 6 TO 9 FEET OVER THE SOUTH END OF THE LAKE BY THURSDAY AFTERNOON. SMALL CRAFT ADVISORY WILL NO DOUBT BE NEEDED BY THURSDAY WITH RIP CURRENTS ALSO LIKELY TO BECOME A PROBLEM ALONG THE INDIANA SHORELINE. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FA.A TIL 11Z 0718 IN...FA.A TIL 11Z 0718 LM...NONE &&
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
450 PM EDT TUE JUL 17 2007 .MESO UPDATE (THRU 6 PM EDT) GUST FRONT APPROACHING OHIO RIVER AND PACKING 30-40 MPH WINDS...WITH BOWING SEGMENT NOTED OVER MADISON COUNTY INDIANA. THIS DECAYING MCS HAS BEEN WEAKENING AS IT MOVES SOUTH AND WE EXPECT THIS TREND TO CONTINUE. UPDATED THE SDF TAF TO ACCOUNT FOR GUST FRONT WITH NO PRECIP AND THEN TSRA 20 MINUTES LATER. WATCHING FOR INTERSECTION OF GUST FRONT MOVING WEST OUT OF LARUE COUNTY AND MOVING WEST INTO HARDIN COUNTY...AND SEE IF ADDITIONAL CONVECTIVE DEVELOPMENT OCCURS IN THIS VERY SULTRY AIRMASS. NO CAP NOTED ON THE LATEST ACARS SOUNDING. STORMS WITH GREATEST PUNCH WILL BE STORMS NEAR BWG MOVING E-NE WHERE MOST UNSTABLE AIRMASS IS. JDG/SLD .SHORT TERM (TONIGHT AND WEDNESDAY)... PRIMARY FOCUS WILL BE ON CONVECTIVE CHANCES FOR THE REST OF THE AFTERNOON AND EVENING. AT 2 PM EDT...WIDESPREAD CONVECTION WAS LOCATED ACROSS THE KENTUCKY BLUEGRASS REGION AND ALONG AN OUTFLOW BOUNDARY THAT STRETCHED FROM SOUTHERN ILLINOIS THROUGH SOUTHWEST INDIANA. CELLS HAVE BEEN MORE SUPPRESSED ACROSS SOUTH CENTRAL KENTUCKY...WHERE SLIGHTLY GREATER INHIBITION AND LESS CONVERGENCE HAS RESTRICTED COVERAGE TO JUST ISOLATED SHOWERS. FEEL THAT THIS OUTFLOW BOUNDARY WILL BE THE FOCUS OF STORMS LATER THIS AFTERNOON...WHILE CONVECTION WILL DIMINISH BY 6 PM ACROSS SOUTH CENTRAL KENTUCKY AND THE BLUEGRASS REGION. THIS LINE WILL MOVE SOUTHEAST ACROSS SOUTHERN INDIANA THROUGH 5 PM AND...SHOULD IT HOLD TOGETHER...CROSS THE OHIO RIVER BY LATE AFTERNOON OR EARLY EVENING. WILL MAINTAIN SCATTERED WORDING THIS EVENING...AS REMNANTS OF OUTFLOW BOUNDARY WILL AT THIS TIME MOVE INTO CENTRAL KENTUCKY. AT SOME POINT...STORMS WILL DIMINISH LATER THIS EVENING EVERYWHERE AS DAYTIME INSTABILITY IS LOST. UPPER AIR PATTERN ACROSS THE CONUS FEATURES A STABLE REGIME WITH RIDGING ACROSS THE NORTHERN ROCKIES...A BROAD TROUGH ACROSS THE GREAT LAKES...AND NORTHWEST FLOW ACROSS THE UPPER MIDWEST. LATER TONIGHT...THE LATEST IN A SERIES OF DISTURBANCES WILL GENERATE A CONVECTIVE CLUSTER OF STORMS NEAR NORTHERN ILLINOIS. HOWEVER...THIS ONE IS EXPECTED TO MOVE FARTHER NORTH ACROSS NORTHERN INDIANA. THE SOUTHERN EDGE OF THIS MAY APPROACH SOUTHERN INDIANA TOWARDS MORNING...AND WILL PLACE AREAS NORTH OF THE OHIO RIVER IN 20% POPS. EXPECT WARM HUMID WEATHER AGAIN TOMORROW. SOUTHWEST FLOW WILL KEEP DEWPOINTS IN THE UPPER 60S AND HIGH PRECIPITABLE WATER VALUES NEAR 2 INCHES. EXPECT SOME AFTERNOON DEVELOPMENT OF CONVECTION...BUT NOT AS WIDESPREAD AS TODAY`S. JSD .LONG TERM (WEDNESDAY NIGHT THROUGH TUESDAY)... WEDNESDAY NIGHT AND THURSDAY... NEARLY STATIONARY BOUNDARY STARTS THE PERIOD TO THE NORTH OF THE REGION ACROSS THE SOUTHERN GREAT LAKES. UPPER LEVEL PATTERN REMAINS NEARLY UNCHANGED...WITH AMPLIFIED RIDGING ACROSS THE MTN WEST...AND EASTERN TROUGH...WITH A SLIGHT FAR SE RIDGE SITTING IN THE NORTHERN GULF AND OVER FLORIDA. ANY CONVECTION WED AFTN SHOULD DISSIPATE WITH LOSS OF HEATING WEDNESDAY...AND NO OTHER TRIGGER. WILL KEEP THE NIGHTTIME HOURS DRY. VERY MOIST AIR IN PLACE AND WSW LOW LEVEL FLOW WILL KEEP OVERNIGHT TEMPS ABOVE NORMAL MID-JULY LOWS...STRUGGLE TO DROP BELOW THE LOWER 70S AREAWIDE. COLD FRONT WILL START TO DRIVE SOUTH TOWARDS THE OHIO VALLEY THURSDAY...INCREASING CLOUDS DURING THE DAY. PWATS WILL SURGE TOWARDS 2 INCHES...AND WITH MODELS SHOWING THE PRECIP EFFICIENCY SHOULD BE HIGH ALONG WITH DEEP WARM CLOUD LAYER...LOCALLY HEAVY RAINFALL AMOUNTS WILL BE POSSIBLE THURSDAY AFTERNOON INTO EARLY FRIDAY MORNING UNTIL THE FRONT PUSHES SOUTH OF THE REGION TOWARDS THE TN VALLEY. DYNAMICS ARE NOT OVERLY STRONG...BUT A FEW STRONGER STORMS WITH GUSTY WINDS AND SMALL HAIL CAN NOT BE RULED OUT. THE COLD FRONT WILL PUSH SOUTH AND OUT OF THE AREA EARLY FRIDAY...WITH SOME CLEARING POSSIBLE INTO SOUTHERN INDIANA AND NORTH CENTRAL KY BY EARLY FRIDAY MORNING. OVERNIGHT LOWS SHOULD HAVE A DECENT GRADIENT FOR SUMMER...WITH LOWER 60S NORTH TO AROUND 70 SOUTH NEAR THE TN BORDER. FRIDAY THROUGH TUESDAY... EXTENDED PORTION OF THE FORECAST HAS BASICALLY REMAINED AS IS COMPARED TO THE PREVIOUS FORECAST...LITTLE ADJUSTMENT NEEDED. THE LONG RANGE MODELS ARE HAVING PROBLEMS WITH THE MID AND UPPER LEVEL PATTERN MUCH OF THE NORTH PACIFIC EAST INTO NORTH AMERICA...DEALING WITH A POSSIBLE DEEP TROUGH OR CUT-OFF LOW SCENARIO OVER THE EASTERN PORTIONS OF NORTH AMERICA. OVERALL THE ENSEMBLES HAVE BEEN FAIRLY CONSISTENT WITH THE PERIOD...AND WILL CONTINUE THE USE OF THE ENSEMBLE MEAN AS THE OPERATIONAL MODELS HAVE BEEN VERY JUMPY AND SOMEWHAT UNRELIABLE. LITTLE WEATHER EXPECTED THOUGH THROUGH THIS PERIOD...MAIN ISSUE IS THE TEMPS AND THE PLACEMENT OF THE UPPER LEVEL TROUGH AND COOLER AIR. SURFACE HIGH PRESSURE LOOKS TO DOMINATE THE PERIOD AS IT PUSHES INTO THE OHIO VALLEY FRIDAY INTO THE WEEKEND. COOLER THAN NORMAL TEMPERATURES WILL BE LIKELY THROUGH THE WEEKEND WITH A SLOW WARMING TOWARDS NORMAL FOR THE START OF THE WORK WEEK. PLENTY OF SUNSHINE AND DRY THROUGH THE PERIOD. LOWER THAN SEASONAL DEWPOINTS WILL BE FOUND THROUGH SUNDAY BEFORE PUSHING BACK INTO THE 60S ON MONDAY. MAIN QUESTION AFTER THAT IS IF THE RIDGING WILL SLIDE EAST OR HOLD ACROSS THE WEST...MUCH UNCERTAINTY REMAINS AFTER DAY 7. --SCHOTT .AVIATION (18Z TAFS)... SCATTERED THUNDERSTORMS WILL CONTINUE THROUGH THE LATE AFTERNOON HOURS AT BWG...LEX AND SDF. SOME OF THESE STORMS MAY BE STRONG WITH LOCALIZED WIND GUSTS UP TO 35-40 MPH. COVERAGE OF THESE STORMS WILL BE 40 TO 50%. WILL COVER THEM IN THE TAFS WITH TEMPO DURING THE PEAK PERIOD OF THUNDERSTORM COVERAGE. THUNDERSTORMS WILL CONTINUE THROUGH THE EVENING HOURS AS AN OUTFLOW BOUNDARY FROM STORMS IN ILLINOIS APPROACH BY LATE AFTERNOON. EXPECT STORMS TO DIMINISH BY LATE EVENING. HAZE OR LIGHT FOG MAY AFFECT THE TAF SITES THROUGH THE EARLY MORNING HOURS. JSD && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
110 PM EDT TUE JUL 17 2007 .AVIATION (18Z TAFS)... SCATTERED THUNDERSTORMS WILL CONTINUE THROUGH THE LATE AFTERNOON HOURS AT BWG...LEX AND SDF. SOME OF THESE STORMS MAY BE STRONG WITH LOCALIZED WIND GUSTS UP TO 35-40 MPH. COVERAGE OF THESE STORMS WILL BE 40 TO 50%. WILL COVER THEM IN THE TAFS WITH TEMPO DURING THE PEAK PERIOD OF THUNDERSTORM COVERAGE. THUNDERSTORMS WILL CONTINUE THROUGH THE EVENING HOURS AS AN OUTFLOW BOUNDARY FROM STORMS IN ILLINOIS APPROACH BY LATE AFTERNOON. EXPECT STORMS TO DIMINISH BY LATE EVENING. HAZE OR LIGHT FOG MAY AFFECT THE TAF SITES THROUGH THE EARLY MORNING HOURS. JSD && .MORNING UPDATE... A CHALLENGING FORECAST IN TERMS OF HOW AFTERNOON CONVECTION WILL EVOLVE. MORNING FORECAST AND ACARS SOUNDINGS SHOW WEAKLY UNSTABLE LAPSE RATES WITH LITTLE OR NO CAP. THERE SHOULD BE LITTLE INHIBITION TO CONVECTION LATER TODAY. THE PROBLEM RESIDES IN THE THE INITIAL TRIGGERING OF STORMS IN THE FIRST PLACE. PRECIPITATION FROM THE REMNENTS OF AN EARLIER MCS ACROSS INDIANA IS ERODING AS IT APPROACHES OUR CWA ACROSS SOUTHERN INDIANA. IS POSSIBLE THAT SOME LIGHT SHOWERS WILL MAKE IT INTO OUR NORTHERN TIER OF COUNTIES BY LATE MORNING. INITIALLY...THESE SHOWERS WILL BE QUITE LIGHT...BUT HAVE AMENDED FORECAST TO INCREASE POPS TO 50% ACROSS OUR NORTH. INCREASED CLOUDINESS WILL LOWER HIGHS ACROSS THE NORTH INTO THE MID 80S. CONVECTIVE INITIATION THIS AFTERNOON MAY OCCUR IN TWO LOCATIONS. THE FIRST MAY BEGIN ACROSS OUR SOUTHEASTERN COUNTIES AND THE HIGHER TERRAIN OF EASTERN KENTUCKY. DEEPER MOISTURE RESIDES THERE...AND THERE HAS BEEN SOME RECENT MID-LEVEL CU DEVELOPMENT. THE OTHER MAY INVOLVE SOME SORT OF A BOUNDARY LEFT BY THE DECAYING MCS. HAVE AMENDED FORECAST TO MENTION SCATTERED CONVECTION THIS AFTERNOON. JSD .SHORT TERM (TODAY AND TONIGHT)... A BROAD UPPER LEVEL TROUGH WILL REMAIN PARKED ACROSS THE GREAT LAKES AND UPPER OHIO VALLEY FOR THIS FORECAST PERIOD. WE WILL SEE RISING HEIGHTS TODAY (WARMER TEMPERATURES) AS A JET MAX MOVES UP THE EAST SIDE OF THE TROUGH. THE SHORT RANGE MODELS ARE IN GOOD AGREEMENT ON THE LARGE SCALE SYNOPTIC PATTERN BUT DIFFER ON SHORT WAVE ENERGY MOVING THROUGH THE UPPER LEVEL FLOW. 00Z BUFKIT SOUNDINGS INDICATE A MARGINALLY UNSTABLE LATE AFTERNOON ATMOSPHERE SO I DON`T SEE ANY AREA WHERE THUNDERSTORMS WILL BE MORE LIKELY THAN OTHERS SO WE WILL GO WITH LOW CHANCE POPS THIS AFTERNOON ACROSS ALL THE FORECAST AREA. WE WILL HOLD ONTO LOW CHANCE OR ISOLATED POPS TONIGHT OVER THE NORTH... CLOSER TO A STATIONARY FRONT LOCATED ACROSS CENTRAL ILLINOIS AND INDIANA. CONVECTIVE COMPLEX MOVING THROUGH CENTRAL AND NORTHERN ILLINOIS THIS MORNING SHOULD REMAIN NORTH OF THE FORECAST AREA BASED ON MID LEVEL FLOW FORECASTS. --JA .LONG TERM (WEDNESDAY THROUGH MONDAY)... SOME MODEL DIFFERENCES IN PRECIP TIMING AND LOCATION...SO FOLLOWED A BLEND OF THE ENSEMBLES AND OPERATIONAL GFS FOR THE EXTENDED. WEDNESDAY-THURSDAY... THE ROCKY MOUNTAIN RIDGE AND HUDSON BAY TROUGH PATTERN AMPLIFIES DURING THIS TIME FRAME...PUTTING THE CWA UNDER A GOOD NWRLY FLOW ALOFT. A QUASI-STATIONARY FRONT EXTENDS EASTWARD FROM LOW PRESSURE OVER THE DAKOTAS...AND THIS BOUNDARY WILL COME INCREASING CLOSER DURING THIS TIME FRAME. WITH A SFC HIGH OFF THE SERN CONUS...GULF MOISTURE WILL POOL NORTHWARD AND PULSE CONVECTION SHOULD BE THE RULE WEDNESDAY AFTN-EVE AND PERHAPS AGAIN ON THURSDAY. GIVEN THE PRECIP COVERAGE OVER THE PAST COUPLE OF DAYS...BUMPED UP POPS TO 40 FOR THE BEST CHANCE OF PRECIP. SINCE NO FORCING MECHANISM IS AROUND WED...WENT WITH HIGHEST POPS OVER THE EAST. FOR THURSDAY...WENT WITH THE HIGHEST POPS NORTH CLOSER TO APPROACHING COLD FRONT. MOST OF THE PRECIP WILL BE DIURNAL...HOWEVER UNDER THE NW FLOW...MAY HAVE AN MCS DIVE SEWD TOWARD THE REGION EARLY WED MORNING. BEST CHANCE OF THIS WOULD BE ACROSS OUR INDIANA COUNTIES AND NRN BLUEGRASS COUNTIES WITH DAMAGING WINDS BEING POSSIBLE IF IT REACHES THE CWA. TEMPS DURING THIS PERIOD WILL BE HOT...WITH LOW 90S POSSIBLE FOR HIGHS BOTH DAYS...AND THE OVERNIGHT PERIODS FEELING MUGGY WITH LOWS AROUND 70 AND DEWPOINTS IN THE 60S. GUSTY SOUTHWEST WINDS WILL BE POSSIBLE ON THURSDAY AHEAD OF THE FRONT. THURSDAY NIGHT-FRIDAY NIGHT... BY THURSDAY EVENING...THE COLD FRONT SHOULD BE NEARING OUR NRN CWA BORDER. WITH HIGH LIKELY POPS IN THE MEX GUIDANCE...AND LOW LIKELY POPS IN THE ENSEMBLES...BUMPED UP POPS THURSDAY NIGHT TO LOW LIKELY POPS. NAM IS MUCH SLOWER ON FRONTAL BOUNDARY MOVEMENT...SO DELAYED THE FROPA A BIT...BUT STILL TRENDED TOWARD THE FASTER GFS...WHICH HAS THE FRONT THROUGH AND ALL PRECIP ENDING BY FRIDAY EVENING. SOME OF THE STORMS WITH THE FRONT COULD BE STRONG-SEVERE WITH MORE DYNAMICS INVOLVED. ALSO BUMPED UP POPS ON FRIDAY TO HIGH CHANCE SOUTH...AND JUST A SLIGHT CHANCE NORTH. HAVE ALL PRECIP ENDING BY 00Z SATURDAY. AL SATURDAY-MONDAY... SURFACE HIGH PRESSURE WILL DIVE SOUTH FROM THE GREAT LAKES LATE FRIDAY AND WILL DOMINATE THE REGION THRU EARLY NEXT WEEK...AS THE UPPER LEVEL TROUGH/CUT-OFF WILL START TO DRIFT OFF TO THE EAST BY MONDAY. TEMPS WILL BE BELOW NORMAL FRIDAY AND SATURDAY WITH THE NW FLOW...AND MUCH DRIER AIR WILL BE IN PLACE. A SLOW RETURN TO MORE SEASONAL DEWPOINTS AND TEMPS LATE INTO THE WEEKEND AND EARLY NEXT WEEK IS EXPECTED. SCHOTT && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
408 PM EDT TUE JUL 17 2007 .SYNOPSIS... 19Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED AN UPPER TROUGH COVERING MUCH OF EASTERN CANADA INTO THE GREAT LAKES WHILE RIDGING EXTENDING FROM THE FOUR CORNERS NORTHWARD INTO ALBERTA. THE MAIN FEATURE WITHIN THE UPPER TROUGH OF CONCERN IS A SHRTWV/UPPER LOW JUST TO THE NW OF CHURCHILL MANITOBA. BANDS OF CLOUDS...AND POSSIBLY A FEW SHOWERS BASED ON THE CLOUD TOPS...EXIST ACROSS NORTHERN MANITOBA INTO SE NUNAVUT ASSOCIATED WITH THE SHRTWV. FAIRLY COLD 500MB TEMPS EXIST TOO...WITH A READING ON THE 12Z RAOB AT CHURCHILL OF -21C. CLOSER TO HOME...CONDITIONS ARE QUITE A BIT WARMER THANKS TO QUITE A BIT OF SUN AND 850MB TEMPS OF 12C PER 12Z RAOBS. READINGS HAVE CLIMBED WELL INTO THE 70S AND EVEN A FEW 80S PRESENT. IN ADDITION...THE HEATING HAS DEVELOPED SOME CUMULUS... THOUGH THESE HAVE BEEN HARD PRESSED TO GET MUCH VERTICAL EXTENT DUE TO THE DEWPOINTS MIXING INLAND INTO THE UPPER 40S F (ALMOST A 10F DROP SINCE THIS MORNING). 17Z TAMDAR SOUNDING FROM SAW SHOWS THAT WITH THESE LOW DEWPOINTS...A CAP EXISTS AROUND 700MB. DIFFERENT SCENARIO EXISTS ACROSS THE WISCONSIN STATE LINE...WHERE DEEPER LOW LEVEL MOISTURE WITH DEWPOINTS IN THE LOW TO MID 60S F HAVE ALLOWED SOME SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP. FARTHER TO THE NW...SOME DIURNAL CUMULUS AND A WEAK SHRTWV INDUCED CLOUDS HAVE DEVELOPED ACROSS SOUTHERN MANITOBA...AND THE RADAR FROM WINNIPEG DEPICTS SOME SCATTERED SHOWERS UNDER THESE CLOUDS. && .SHORT TERM (TONIGHT AND WED)... AS THE SHORTWV/UPPER LOW NEAR CHURCHILL MANITOBA APPROACHES OUR CWA...MODELS DIFFER IN THE GENERATION OF PCPN. LOCAL WRF-ARW 06Z RUN AND SUBSEQUENT 12Z HI-RES RUN PRODUCE A STRONGER SHORTWAVE THAT GENERATES SHOWERS OVERNIGHT TONIGHT THROUGH WED MORNING. THE LATEST 12Z RUN HAS THE SHOWERS DISSIPATING BEFORE THEY REACH OUR CWA. 13 KM RUC/NAM ALSO HINT AT A CHANCE OF PCPN 12Z-18Z WED. BECAUSE OF THIS UNCERTAINTY...WENT WITH A CHANCE OF PCPN ALL DAY RATHER THAN JUST IN THE AFTERNOON. KEPT WED AFTERNOON CHANCE OF SHOWERS AND THUNDERSTORMS OVER LAND...BUT DIMINISHED POPS OVER MARINE AREAS. DIURNAL HEATING AND ADDITIONAL WEAK SHORTWAVES OSCILLATING AROUND CLOSED 500MB LOW NEAR HUDSON BAY WILL GIVE THE OPPORTUNITY FOR WED AFTERNOON SHOWERS AND/OR THUNDERSTORMS...MAINLY OVER THE WEST HALF AND INTERIOR EAST HALF...ALONG LAKE BREEZE CONVERGENT ZONES. .LONG TERM (WED NIGHT THROUGH NEXT TUE)... MAIN FORECAST CONCERN IS PCPN CHANCES WITH UPPER LOW/SHRTWV DIVING INTO THE AREA WED NIGHT. WED NIGHT...UPPER LOW/SHRTWV SHOULD BE LOCATED UP IN FAR NW ONTARIO AT 00Z THU. MODELS PROG THIS FEATURE DROPPING SE TO THE NE END OF LAKE SUPERIOR BY 12Z. WILL MAINTAIN A CHANCE FOR SHOWERS AND THUNDERSTORMS IN THE EVENING...EITHER FROM A COMBINATION OF LEFTOVER DIURNAL CONVECTION ON WED OR FROM PCPN DEVELOPING IN THE STRONG MID LEVEL FRONTOGENESIS AND 700-300MB Q-VECTOR CONVERGENCE THAT OCCURS DOWNSTREAM OF THE SHRTWV. IT STILL APPEARS THAT THE BULK OF THE PCPN WILL END OVER THE WESTERN AND NORTH CENTRAL U.P. AFTER 06Z. HOWEVER...AM HIGHLY CONCERNED THAT WITH THE COLD ADVECTION COMING IN (850MB TEMPS FALL TO +6C OVER THE KEWEENAW BY 12Z)...THAT SOME STRATUS MAY DEVELOP. IF IT DOES...AS IT DID LAST SAT MORNING...WE MAY HAVE SOME DRIZZLE TO CONTEND WITH. THIS IS DEPICTED IN THE 12Z GFS QPF FIELD OVER BARAGA COUNTY WITH 0.01 BTWN 06-12Z. SINCE THIS SEEMS REASONABLE...HAVE DECIDED TO MENTION DRIZZLE IN THE FORECAST FOR UPSLOPE AREAS. COOLER TEMPS THAN LAST NIGHT...THOUGH STILL IN THE 50S...ARE EXPECTED. THU...UPPER LOW/SHRTWV IS PROGGED TO CONTINUE DROPPING SE DOWN THE EAST SIDE OF THE ROCKIES RIDGE...THOUGH THERE IS SOME SPREAD ON ITS INTENSITY. THE UKMET SHOWS A GENERAL TROUGH...WITH THE STRONGEST SHRTWV LOCATED OVER GEORGIAN BAY. THE GFS HAS A STRONG SHRTWV/UPPER LOW IN NORTHERN LOWER MI. THE 00Z ECMWF WAS NOT FAR OFF THE GFS. THE NAM IS AN OUTLIER WITH AN OVER DEVELOPED TROUGH COMPARED TO THE OTHER MODELS. THEREFORE PLAN ON FOLLOWING THE GFS/ECMWF IDEA. NO MATTER WHAT HAPPENS...BREEZY...NORTHERLY COLD ADVECTION WILL RESULT IN STRATUS DEVELOPMENT OVER MUCH OF THE CWA IN THE MORNING...WITH DRIZZLE OVER UPSLOPE AREAS. AFTER 18Z...THE COMBINATION OF DRY AIR ADVECTION OUT OF CANADA AND LAKE STABILIZATION SHOULD HELP CLEAR THINGS OUT. GIVEN COOLER 850MB TEMPS...AROUND 6C ACROSS MUCH OF UPPER MI AT 18Z...TEMPS WILL BE QUITE A BIT COOLER THAN WED...WITH READINGS ACROSS THE NORTHERN U.P. REACHING NO HIGHER THAN THE LOW TO MID 60S. NORTH WINDS DOWNSLOPE IN THE SOUTHERN U.P....AND SINCE THIS DOWNSLOPING MAY ALSO HELP IN GETTING THE AREA MORE SUN COMPARED TO THE NORTH...THOSE AREAS SHOULD CLIMB INTO THE LOW 70S. THU NIGHT INTO FRI...1020MB HIGH PRESSURE IS EXPECTED TO BE LOCATED NEAR THE INTERSECTION OF MANITOBA...NORTHERN ONTARIO AND NORTHERN MN AT 00Z FRI. THIS HIGH WILL BUILD INTO THE AREA AS THE SHRTWV/UPPER LOW CONTINUES OFF TO TOWARDS THE APPALACHIANS. DRY AIR ADVECTING IN WITH THIS HIGH (PRECIPITABLE WATER DOWN TO 0.50 INCH BY 06Z FRI) ALONG WITH UPPER LEVEL SUBSIDENCE SHOULD KEEP THINGS DRY THROUGH THE PERIOD. GIVEN THE DRY AIR AND COOL TEMPS ON THU...READINGS MAY GET QUITE CHILLY THU NIGHT...ESPECIALLY IN THE INTERIOR WHERE SKIES CLEAR OUT AND WINDS DECOUPLE. 00Z MAV COOP GUIDANCE FOR CHAMPION IS 42...WHICH SEEMS REASONABLE AT THIS POINT IN TIME. PLENTY OF SUNSHINE ON FRI COMBINED WITH 850MB TEMPS AT 18Z AROUND 8C AND DRY AIR SHOULD ALLOW DEEP MIXING...THUS RESULTING IN HIGHS INLAND AND ALONG LAKE MICHIGAN INTO THE MID TO UPPER 70S. NORTHERLY FLOW PERSISTING ALONG LAKE SUPERIOR WILL KEEP TEMPS A BIT COOLER...ESPECIALLY RIGHT AT THE SHORE. FRI NIGHT THROUGH NEXT TUE...THERE REMAINS CONSIDERABLE UNCERTAINTY ON WHAT HAPPENS TO THE EASTERN TROUGH AT THE BEGINNING OF THE PERIOD...WHICH IMPACTS TEMPERATURES THROUGH THIS PERIOD AND WHETHER OR NOT A COLD FRONT WILL DROP DOWN INTO THE CWA AROUND MON. MODELS ARE IN GOOD AGREEMENT SUGGESTING A STRONGER FLOW COMING OUT OF THE PACIFIC...WHICH HELPS TO PUSH THE RIDGE THAT HAS PERSISTED OVER WESTERN NORTH AMERICA TOWARDS THE WESTERN GREAT LAKES. IF THE FLOW IS SLOW ENOUGH...THE ENTIRE EASTERN TROUGH SHOULD LIFT OUT AND ALLOW RIDGING TO BUILD IN QUICKER...AS SUGGESTED BY THE 16/12Z ECMWF AND 17/00Z AND 12Z UKMET/CANADIAN. HOWEVER...IF THIS FLOW IS TOO FAST...THEN THE EASTERN TROUGH WILL CUT-OFF INTO TWO AND FORCE THE RIDGING INTO NW ONTARIO...AS SUGGESTED BY THE 06Z/12Z GFS AND 16/00Z...17/00Z AND 17/12Z ECMWF RUNS. WHERE THIS CUT-OFF TAKES PLACE IS ALSO IN QUESTION...WITH THE 17/00Z ECMWF AND 12Z GFS HAVING IT MUCH FARTHER WEST THAN ANY OF THE OTHER MODELS (OVER INDIANA AT 00Z TUE). FOR NOW WILL FOLLOW THE ASSUMPTION FROM YESTERDAY THAT A CUT-OFF WILL DEVELOP...BUT LOCATED SOMEWHERE BETWEEN THE 17/00Z ECMWF AND 06Z GFS. FOR FRI NIGHT THROUGH SUN NIGHT...DRY CONDITIONS ARE STILL PLANNED...WITH BOTH DRY AIR AND INCREASED CAPPING THROUGH THE PERIOD. ON MON...A COLD FRONT OR WEAKENING TROUGH WILL DROP DOWN INTO THE CWA...THOUGH IT APPEARS THERE IS TOO MUCH CAPPING AND DRY AIR AROUND TO ALLOW FOR ANY CONVECTION TO DEVELOP ALONG IT...EVEN WITH LAKE BREEZE CONVERGENCE. AFTER THE PASSAGE OF THE TROUGH...EVEN WARMER AIR SHOULD ENTER THE AREA...MAINTAINING DRY CONDITIONS. HOWEVER...UNTIL THE ECMWF BACKS OFF THE IDEA OF THE CUT-OFF EASTERN TROUGH LOW ROTATING WESTWARD...WILL HOLD OFF ON GOING TOO HIGH WITH TEMPERATURES. IT SHOULD BE NOTED THAT IF THE CUT-OFF IS FARTHER EAST AS THE 06Z GFS INDICATES...850MB TEMPS OF 20-24C ADVECTING INTO THE CWA LATE SUN WILL STAY AROUND THROUGH MUCH OF NEXT WEEK...THUS RESULTING IN AN EXTENDED PERIOD OF HEAT FOR UPPER MICHIGAN. COOLER CONDITIONS WOULD OCCUR THOUGH NEAR THE LAKESHORES AS THE PRESSURE GRADIENT IS NEVER STRONG ENOUGH TO PREVENT AFTERNOON LAKE BREEZES. CHANGES WILL LIKELY BE MADE FOR MONDAY AND TUESDAY...EITHER IN TEMPERATURES OR PRECIPITATION CHANCES...WHEN THE MODELS AGREE MORE ON WHAT HAPPENS WITH THE EASTERN TROUGH FROM FRI. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. AN UPPER LEVEL DISTURBANCE APPROACHING THE UPPER GREAT LAKES WILL BRING MID CLOUD COVER OVERNIGHT. THERE IS A CHANCE THAT MVFR CONDITIONS MAY EXIST (LOWER CLOUDS) BY WED AFTERNOON IF PCPN STARTS EARLIER THAN GOING FCST. && .MARINE (FOR 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... WINDS WILL BE LESS THAN 20 KNOTS THROUGH THE FORECAST PERIOD. HIGH PRESSURE OVER SOUTHERN MANITOBA AND LOW PRESSURE OVER THE LOWER GREAT LAKES WILL CREATE A STRONGER PRESSURE GRADIENT ON THURSDAY...RESULTING IN 15 TO 20 KT WINDS ON LAKE SUPERIOR. FROM THEN ON...HIGH PRESSURE WILL DOMINATE THE UPPER GREAT LAKES AND LIGHT WINDS WILL PREVAIL. && $$ SHORT TERM/AVIATION/MARINE...MRC SYNOPSIS/LONG TERM...AJ
AREA FORECAST DISCUSSION
NWS MISSOULA MT
1032 AM MDT TUE JUL 17 2007 .DISCUSSION...MID AND HIGH LEVEL MOISTURE HAS BEGAN TO STREAM INTO THE NORTHERN ROCKIES THIS MORNING. THE INCREASED CLOUD COVER WILL KEEP TEMPERATURES SLIGHTLY COOLER THAN YESTERDAY...BUT STILL WELL ABOVE NORMAL FOR THIS TIME OF YEAR. CURRENTLY A DISTURBANCE IS MOVING THROUGH EASTERN OREGON AND CENTRAL IDAHO. THIS DISTURBANCE WILL MAKE ITS WAY INTO WESTERN MONTANA AND NORTH CENTRAL IDAHO BY THIS AFTERNOON BRINGING WIDESPREAD CONVECTION...SO HAVE ADJUSTED THE CHANCE OF PRECIPITATION. THE FORECAST WILL HAVE TO BE MONITORED FOR FURTHER UPDATES. && .AVIATION...WIDELY SCATTERED SHOWERS CONTINUE IN SOUTHWEST MONTANA THIS MORNING. AIRCRAFT FLYING THROUGH THIS AREA AND AROUND THE KBTM TERMINAL SHOULD BE AWARE OF POTENTIAL GUSTY WINDS ASSOCIATED WITH THESE STORM CELLS THIS MORNING. THIS AFTERNOON ANOTHER STORM SYSTEM PUSHES THROUGH AND WILL CAUSE WIDESPREAD CONVECTION WITH ELEVATED POTENTIAL FOR GUSTY WINDS AND TURBULENCE LATE MORNING THROUGH THIS EVENING THROUGHOUT WESTERN MONTANA AND NORTH CENTRAL IDAHO...PLEASE SEE APPROPRIATE TAFS AND TWEBS. && .PREV DISCUSSION... /ISSUED 329 AM MDT TUE JUL 17 2007/ DISCUSSION...A DEEP LOW PRESSURE SYSTEM DRIFTING CLOSER TO THE OREGON COAST HAS BEGUN TO PUMP SUB-TROPICAL MOISTURE NORTHWARD TOWARDS THE NORTHERN ROCKIES REGION. SATELLITE IMAGERY CLEARLY SHOWS A DISTURBANCE MAKING ITS WAY NORTH THROUGH NORTHEAST NEVADA/SOUTHERN IDAHO EARLY THIS MORNING. THE AIR MASS REMAINS WARM AND UNSTABLE WITH THE BIGGEST CHANGE FOCUSED AROUND INCREASED MOISTURE...EXPANDING THE SHOWER/THUNDERSTORM POTENTIAL THROUGHOUT NORTH-CENTRAL IDAHO AND WESTERN MONTANA. INCREASED CLOUD COVER AND SHOWERS WILL HELP HOLD TEMPERATURES DOWN IN INTO THE UPPER 80S AND 90S IN MOST LOCATIONS. NORTHWEST MONTANA WILL SEE SOME OF THE WARMER TEMPERATURES DUE TO THE LATER ARRIVAL OF CLOUDS AND SHOWERS. CONVECTION WILL CONTINUE INTO THE EVENING HOURS BEFORE TAPERING OFF AFTER MIDNIGHT. WEDNESDAY AND WEDNESDAY NIGHT...THE MODELS HAVE BEEN CONSISTENT WILL THE STRENGTHENING OF THE UPPER RIDGE AND MIGRATION OF DRIER AIR INTO THE AREA FROM THE SOUTH. SKIES ARE EXPECTED TO CLEAR BY MORNING. THE AIR MASS WILL REMAIN VERY WARM AND QUITE UNSTABLE. THUS...AFTERNOON BUILDUPS AND ISOLATED LATE-DAY THUNDERSTORMS ARE STILL IN THE FORECAST PICTURE...MAINLY ALONG THE CONTINENTAL DIVIDE AND NORTHWEST MONTANA. THURSDAY...THE AFOREMENTIONED LOW SYSTEM OFF THE OREGON COAST WILL KICK INLAND OVER THE PACIFIC NORTHWEST AS AN OPEN TROUGH AND SWEEP NORTHWARD BRUSHING BY OUR WESTERN ZONES. THIS WILL EFFECTIVELY SHOVE THE INVERTED SURFACE TROUGH ACROSS WESTERN MONTANA LATER IN THE DAY. THE COMBINATION OF WINDS ALOFT MIXING THE SURFACE AND AN INCREASED SURFACE PRESSURE GRADIENT WILL RESULT IN INCREASED WINDS. WINDS COUPLED WITH EXISTING HOT DRY CONDITIONS WILL RAISE FIRE WEATHER CONCERNS...ESPECIALLY AFTER A CONVECTIVELY ACTIVE PERIOD. THURSDAY NIGHT THROUGH MONDAY...AS THE SYSTEM MOVES QUICKLY TO THE NORTH INTO CANADA A STRONG SURFACE PRESSURE GRADIENT WILL KEEP BREEZY CONDITIONS INTO THE EVENING HOURS THURSDAY. THE HIGH PRESSURE RIDGE WILL BEGIN TO PUSH BACK TO THE NORTH AND ALLOW FOR ANOTHER WARMING TREND THROUGH THE WEEKEND. TEMPERATURES ARE EXPECTED TO BE NEAR THE CENTURY MARK AGAIN ON SATURDAY AND SUNDAY. FRIDAY SHOULD BE MOSTLY SUNNY AND DRY. ON SATURDAY A WAVE OF ENERGY WILL PASS THROUGH AND COUPLED WITH A RELATIVE INCREASE IN MOISTURE WILL BRING CHANCES FOR SHOWERS AND THUNDERSTORMS PARTICULARLY ALONG THE CONTINENTAL DIVIDE DURING THE AFTERNOON. A SIMILAR SETUP WILL FORM ON SUNDAY AND MONDAY AFTERNOONS AS WELL AND SLIGHT CHANCES FOR THUNDERSTORMS ARE EXPECTED AGAIN ALONG THE DIVIDE. FIRE WEATHER...THUNDERSTORMS ACTIVITY WILL INCREASE TODAY AS WELL EXPAND INTO NORTHWEST MONTANA. THE AIR MASS IS EXPECTED TO DRY AND WARM...THUS RETURNING TEMPERATURE READINGS BACK TOWARDS NEAR RECORD LEVELS ON WEDNESDAY. THURSDAY...THERE IS A GROWING CONCERN THAT A COMBINATION OF INCREASED WINDS...HOT DRY CONDITIONS AND EVEN A POTENTIAL OF ISOLATED LATE AFTERNOON THUNDERSTORMS WILL PROVIDE AN ACTIVE BURNING PERIOD. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...NONE. ID...NONE. && $$ SHORT TERM...SMITH PREV DISCUSSION....MSJ/FOSTER AVIATION...FOSTER