Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 10/12/07

AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
830 PM PDT THU OCT 11 2007 .SYNOPSIS... A TROUGH WILL BRING COOL AND BREEZY CONDITIONS FRIDAY AND SATURDAY ALONG WITH A CHANCE OF RAIN WEST OF THE DESERTS EARLY FRIDAY EVENING THROUGH SATURDAY MORNING. WARMER SUNDAY...COOLER EARLY NEXT WEEK... THEN WARMER AFTER MIDWEEK. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES. A PROGRESSIVE PATTERN IS EXPECTED FRIDAY THROUGH WEDNESDAY WITH A COUPLE OF WEAK TROUGHS KEEPING CONDITIONS COOL AND THE MARINE LAYER DEEP. A CHANCE OF PRECIP MAINLY LATE FRIDAY NIGHT. A WARMING TREND UNDER WEAK OFFSHORE FLOW IS INDICATED FOR THURSDAY AND FRIDAY OF NEXT WEEK. DETAILS FOLLOW... TONIGHT...576 SW FLOW ALOFT WITH MODEST 5 MB ONSHORE FLOW SHOULD MAINTAIN A 1500 FT DEEP MARINE LAYER WITH PATCHY LOW CLOUDS AND FOG REACHING THE WESTERN VALLEYS. FRIDAY...COOLER AS A BROAD 560 UPPER LOW SWEEPS ACROSS CENTRAL CALIF BRINGING BRISK 573 CYCLONIC W FLOW ALOFT...AND MODERATE 10 MB ONSHORE FLOW TO A 1001 MB SURFACE LOW OVER VEGAS. SOME HIGH CLOUDS AS THE TROF AND COLD FRONT APPROACH FROM THE NW DURING THE AFTERNOON. RECENT MODELS BUMP UP THE QPF A BIT AND START PRECIP A BIT EARLIER...SO THE FRONT SHOULD BRING .05 TO .2 INCH OF RAIN FRI EVENING THROUGH SAT MORNING. THE MARINE LAYER WILL DEEPEN TO 10K FEET. COULD BE A BRIEF DUSTING OF SNOW DOWN TO 8000 FT IN THE SBD MTS. WIND ADVISORY IN EFFECT FOR MOUNTAINS FRIDAY AFTERNOON INTO SATURDAY AS A 115 KT WESTERLY JET MAX ROUNDS THE BOTTOM OF THE TROUGH AND PASSES OVERHEAD. BEING UNDER THE RIGHT REAR QUAD OF THE JET AND FAIR OROGRAPHICS FAVORS PRECIP. STRONG MOUNTAIN WAVE CONDITIONS OVER THE SAN DIEGO MTS. SATURDAY...THE 562 UPPER LOW PROGRESSES EASTWARD INTO UTAH LEAVING 573 CYCLONIC NW FLOW OVER US BY AFTERNOON. AFTER RESIDUAL SHOWERS IN THE MORNING...PARTLY CLOUDY AND CONTINUED COOL AND MOIST WITH 5 MB ONSHORE FLOW. A DEEP EXTENSIVE MARINE LAYER IS EXPECTED SAT NIGHT. SUNDAY...WARMER UNDER 580 UPPER RIDGE AND WEAK ONSHORE FLOW. DEEP MARINE LAYER IN THE MORNING WITH REVERSE CLEARING POSSIBLE. ANOTHER DEEP MARINE LAYER SUN NIGHT. MONDAY...BROAD...WEAK 573 TROUGH APPROACHES. MODELS CONTINUE TO TREND WEAKER WITH THIS SYSTEM. NOW ONLY A MODEST MODERATE 5 MB ONSHORE FLOW TO 1007 MB SURFACE LOW OVER NEVADA. NO PRECIP. 1500 FT DEEP MARINE LAYER MON NIGHT. TUESDAY...BRISK 578 WESTERLY FLOW ALOFT AND MODERATE 8 MB ONSHORE FLOW TO A 1005 MB LOW OVER NEVADA. DEEP MARINE LAYER MAY CAUSE DRIZZLE TUE NIGHT. POSSIBLE WIND ADVISORY FOR THE MOUNTAINS AS A 120 KT WESTERLY JET MAX SETS UP NORTH OF OUR AREA. WEDNESDAY...SLIGHTLY WARMER UNDER 582 WNW FLOW ALOFT AND WEAK ONSHORE FLOW. BREEZY MTS. SHALLOW PATCHY MARINE LAYER WED NIGHT DUE TO WEAK OFFSHORE FLOW COMPONENT FROM A 1020 MB HIGH OVER CEN CALIF. THURSDAY...590 UPPER HIGH DEVELOPS ABOUT 1000 MI SW OF SAN DIEGO CAUSING WEAK 586 W FLOW OVER US. TEMPS WARM TO SLIGHTLY ABOVE NORMAL UNDER WEAK 5 MB OFFSHORE FLOW FROM A 1022 MB HIGH OVER UTAH. FRIDAY...582 WEST FLOW AND INCREASING ONSHORE FLOW WILL CAUSE SLIGHT COOLING...AND COULD DRAG A REMNANT MARINE LAYER FRONT FOR INCREASING LOW CLOUDS FRI NIGHT. && && .SGX WATCHES/WARNINGS/ADVISORIES...NONE. && .AVIATION... 120305Z...ACARS SOUNDINGS SHOW THAT THE MARINE INVERSION HAS LOWERED A BIT FURTHER...TO ABOUT 1300 FEET. KOKB HAS A CIG AT THAT LEVEL ALREADY...AND THAT SHOULD SPREAD TO MOST OTHER PARTS OF THE COAST BY 06Z. CIGS WILL GENERALLY REMAIN AROUND 1300 FEET MSL OVERNIGHT AND MOSTLY CLEAR BY 17Z FRI. GUSTY WINDS WILL OCCUR FRI AFTERNOON/EVENING OVER THE MTNS AND DESERTS WITH ASSOCIATED UPDRAFTS/DOWNDRAFTS. OTHERWISE...ABOVE THE MARINE LAYER...VFR CONDITIONS WILL PREVAIL WITH UNLIMITED VSBYS AND INCREASING CLOUDS...BUT GENERALLY ABOVE 15000 FEET FRI...LOWERING TO 10000 FEET FRI EVENING AS A SYSTEM APPROACHES FROM THE NW. && $$ PUBLIC...MACKECHNIE AVIATION...MAXWELL
AREA FORECAST DISCUSSION
NWS GAYLORD MI
959 PM EDT THU OCT 11 2007 .UPDATE...(SECOND UPDATE)...NOT A LOT GOING ON IN THE LARGE SCALE SCHEME OF THINGS THIS EVENING...AS TWIN UPPER LOWS TO THE EAST CONTINUE THE PROCESS OF DUMBELLING AROUND ONE ANOTHER. WATER VAPOR IMAGERY DOES SHOW SOME DRYING/SUBSIDENCE ROTATING SOUTHWESTWARD TOWARD NORTHERN MI. 00Z APX SOUNDING INDICATED INVERSION HEIGHTS AROUND 800MB/-5C...850MB TEMPERATURE NEAR -3C WITH COLDER TEMPERATURES TO THE NORTH PER AIRCRAFT SOUNDINGS (-4 TO -5C ACROSS THE UPPER PENINSULA). SCATTERED SHOWERS CONTINUE NEAR LAKE HURON...SOME SHOWERS HAVE ALSO BLOSSOMED QUICKLY AROUND GRAND TRAVERSE BAY...LOOKS LIKE ALONG NORTH-SOUTH CONVERGENCE AXIS EVIDENT IN RADAR IMAGERY BACKING ITS WAY WESTWARD INTO THE BAY. MORE RAIN SHOWERS OCCURRING OVER LAKE SUPERIOR...WITH MONTREAL RIVER RADAR INDICATING SOME OF THIS ACTIVITY BRUSHING FAR WESTERN CHIPPEWA COUNTY. ACROSS EASTERN UPPER...WINDS INITIALLY NORTH/NORTHEAST ACROSS EASTERN UPPER...KEEPING LOW LEVEL TRAJECTORIES PRIMARILY OUT OF ONTARIO (AND DOWNSLOPING TO BOOT). THIS WILL SLOWLY CHANGE OVERNIGHT AS WINDS BACK TO NORTH-NORTHWEST LATE. WILL CARRY SOME EARLY SHOWERS ACROSS FAR WESTERN CHIPPEWA COUNTY...THEN SPREAD THIS ACTIVITY A BIT FARTHER INLAND TOWARD MORNING AS WINDS SHIFT. AREAS ALONG-EAST OF I-75 WILL PROBABLY SEE PARTLY CLOUDY SKIES FOR THE MOST PART OVERNIGHT. ACROSS NORTHERN LOWER...INVERSION HEIGHTS FORECAST TO POKE ABOVE 800MB OVERNIGHT AS LOW/MID LEVEL COLD ADVECTION WINS OUT OVER GENERAL ONGOING SUBSIDENCE. SO SHOWER ACTIVITY EXPECTED TO CONTINUE PREDOMINANTLY IN AREAS FAVORED BY NORTHERLY FLOW... THOUGH MEAN LOW LEVEL FLOW EXPECTED TO BACK MORE NORTHWEST LATE. WILL MAKE SOME TWEAKS TO THE TEMPERATURE GRIDS AS WELL GIVEN VARYING AMOUNTS OF CLOUD COVER ACROSS THE AREA OVERNIGHT. JPB && .PREV DISCUSSION... /ISSUED 800 PM EDT THU OCT 11 2007/ FIRST UPDATE...IN LIEU OF ISSUING AN AVIATION DISCUSSION THAT NO ONE IS GOING TO READ...WILL ISSUE AN EARLY UPDATE SINCE HAVE ALREADY MADE CHANGES TO THE GRIDS. SCATTERED SHOWERS HAVE BEEN DEVELOPING EAST OF I-75 THIS EVENING...AS OPPOSED TO WEST OF I-75 WHERE EARLIER SPOTTY PRECIPITATION HAS DISSIPATED. A LITTLE DRIER ALOFT OVER UPPER MI/NORTHWEST LOWER PER RECENT AIRCRAFT SOUNDINGS MAY BE A FACTOR IN THIS. THIS IS NOT LIKELY TO CHANGE OVERNIGHT... THOUGH IT IS GETTING COLDER ALOFT (EARLY PEEK AT INCOMING APX SOUNDING DATA INDICATES 850MB TEMPERATURES DOWN TO -2.5C). HAVE REMOVED SHOWER MENTION FOR NORTHWEST LOWER THIS EVENING...WILL KEEP IT IN OVERNIGHT FOR NOW GIVEN INCREASING OVER WATER INSTABILITY AND RE-EVALUATE THROUGH THE EVENING. HAVE ADDED SHOWERS TO NORTHEAST LOWER GIVEN CURRENT ACTIVITY. HAVE MESSED AROUND WITH CLOUD COVER A BIT AS WELL WITH BREAKS ACROSS PARTS OF EASTERN UPPER AND THE TIP OF THE MITT...COULD END UP BEING THAT AREAS AROUND THE ST. MARY`S RIVER STAY PARTLY CLOUDY OVERNIGHT. WILL BE ISSUING ANOTHER DISCUSSION AROUND 0215Z. NEW GRIDS ALREADY PUBLISHED. JPB DISCUSSION... /ISSUED 355 PM EDT THU OCT 11 2007/ WEAK SURFACE TROUGH REMAINS OVER THE WRN GREAT LAKES REGION LATE THIS AFTERNOON. DEPARTING UPPER LOW IS MOVING EAST THRU PENNSYLVANIA...WHILE ANOTHER UPPER LOW IS DROPPING SOUTH FROM JAMES BAY TOWARD LAKE HURON. SKIES REMAIN MOSTLY CLOUDY ACROSS OUR ENTIRE CWA. ERN UPR AND FAR NRN LWR MICHIGAN AWAY FROM PROMINENT LAKE INFLUENCES TRIED TO BREAK OUT OF THE CLOUDS...BUT TO NO AVAIL AS SELF-DESTRUCT SUNSHINE LEAD TO ONLY MORE CLOUD DEVELOPMENT WITH LIMITED LOW LEVEL MOISTURE TRAPPED BELOW THE INVERSION. LAKE EFFECT RAIN SHOWERS...ON THE OTHER HAND...HAVE TENDED TO DIMINISH OVER TIME THIS AFTERNOON AS REMAINING MOISTURE APPEARS TO BE TOO SHALLOW TO SUPPORT SIGNIFICANT PRECIP PRODUCTION DESPITE DELTA T`S IN THE MID TO UPPER TEENS. PRIMARY FORECAST QUESTION OVER THE NEXT 24 HOURS WILL BE POPS...AMOUNT AND COVERAGE...AS THE UPPER LOW TO THE NORTH PLUNGES SOUTH INTO SE ONTARIO. ADDITIONAL CONCERNS WILL BE TEMPS (SPECIFICALLY TEMP PROFILE) AND WINDS (SPEED AND DIRECTION) AS MORE COLD AIR ACCOMPANIES THIS UPPER LOW FEATURE. TONIGHT AND FRIDAY...JAMES BAY LOW WILL STEADILY DROP SOUTH ALONG THE ONTARIO/QUEBEC BORDER TONIGHT AND THEN INTO SE ONTARIO ON FRIDAY. A REINFORCING SHOT OF COLD AIR WILL ACCOMPANY THIS SYSTEM. 850 MB TEMPS DROP TO -3 C BY 12Z FRIDAY AND REMAIN UNCHANGED THROUGHOUT THE DAY. LOW LEVEL WINDS WILL GRADUALLY SHIFT FROM DUE NORTH THIS EVENING TO NORTHWEST BY MIDDAY FRIDAY. MAIN LIMITING FACTOR TO PRECIP PRODUCTION (SYNOPTIC OR LAKE EFFECT) WILL BE SHALLOW AND RATHER SPARSE LOW LEVEL MOISTURE. 900-700 MB RH WILL REMAIN AT AROUND 50-60 PCT THRU FRIDAY...ALTHOUGH A BIT HIGHER (NEAR 70 PCT) FOR NE SECTIONS OF OUR CWA CLOSER TO THE APPROACHING UPPER LOW. A LOOK AT UPSTREAM OBS DOES INDICATE LIGHT RAIN/SNOW SHOWERS OCCURRING ALONG THE SW SIDE OF THE UPPER LOW NORTH OF LAKE SUPERIOR AND SAULT STE MARIE AIDED BY A SHORT WAVE ROTATING AROUND THE UPPER LOW. HOWEVER...THESE AREAS ARE STILL NOT WITHIN THE AREA OF DEEP WRAP-AROUND MOISTURE ASSOCIATED WITH THE LOW CENTER. THIS MOISTURE WILL NOT REACH OUR CWA UNTIL FRIDAY NIGHT. THUS...ANY PRECIP OVER THE NEXT 24 HOURS WILL REMAIN LIGHT AND SPOTTY...WITH FOCUS OF CHANCE POPS SHIFTING FROM N FLOW LOCATIONS THIS EVENING (I.E. THE LEELANAU PENINSULA TO MANISTEE) TO N/NW FLOW LOCATIONS OVERNIGHT (I.E. WEST OF US-131) AND THEN TO NW FLOW AREAS ON FRIDAY (I.E. ALONG AND WEST OF US-131...PRESQUE ISLE TO THUNDER BAY...AND NRN SECTIONS OF CHIPPEWA COUNTY. MODELS SOUNDINGS SHOW ZERO ISOTHERM TRYING TO DROP BELOW 2500 FT...BUT JUST FALLING SHORT. THUS...EXPECT ALL PRECIP SHOULD REMAIN LIQUID. MOST OF OUR NEARSHORE AREAS WILL CONTINUE TO EXPERIENCE WIND GUSTS TO 25 KTS TONIGHT THRU FRIDAY (AT LEAST) AS SURFACE PRESSURE GRADIENT REMAINS TIGHT ON THE BACKSIDE OF THE APPROACHING UPPER LOW. WILL THEREFORE EXTEND SCA`S THRU 00Z SATURDAY. LONGER RANGE FORECAST (FRIDAY NIGHT THROUGH NEXT THURSDAY)...LOTS OF QUESTION MARKS DURING THIS PERIOD AS EXTENDED MODELS OFFER A VARIETY OF SOLUTIONS. IT DOES NOT APPEAR AS THOUGH IT WILL WARM UP THIS WEEKEND AS THE MODELS CONTINUE TO TREND ON THE COOLER SIDE. NEXT WEEK IS WHERE THE MAIN CONCERNS ARE AS MODELS VARY ON THE MOVEMENT/ STRENGTH OF A CUTOFF UPPER LOW PROGRESSING TO THE EAST OUT OF THE SOUTHERN STATES. THE INTERACTION OF THIS SYSTEM WITH AN OMEGA BLOCK HIGH WILL BE THE MAIN FOCUS OF THIS PORTION OF THE PACKAGE. FRIDAY NIGHT...MODELS BRING CUTOFF UPPER LOW CURRENTLY EVIDENT ON WATER VAPOR LOOP NEAR GEORGIAN BAY SOUTHWARD AND EVEN APPEAR TO RETROGRADE THIS FEATURE TO THE WEST JUST A TAD. MEANWHILE...OVER LAKE INSTABILITY CONTINUES WITH DELTA TS REMAINING IN THE MIDDLE TO UPPER TEENS. MOISTURE IS ON THE UPTICK WITH MEAN 900-700 MB RH INCREASING TO BETWEEN 90 AND 95 PERCENT NORTHEAST AND 60 TO 70 PERCENT FAR SOUTH. THEREFORE...CONTINUED CHANCE OF LAKE EFFECT RAIN SHOWERS ACROSS NORTHWEST FLOW AREAS AND ADDED A SLIGHT CHANCE OF SHOWERS ACROSS THE NORTHEAST DUE TO SOME LIMITED SYNOPTIC SUPPORT FROM THE UPPER LOW WHICH INCHES A LITTLE CLOSER. LOWS IN THE MIDDLE TO UPPER 30S. SATURDAY...MODEL SOUNDINGS/CROSS SECTIONS SHOW LOW LEVEL MOISTURE LINGERING IN THE MORNING (MEAN 900-700 MB RH STILL 85 TO 95 PERCENT) BUT SLOWLY DISSIPATING IN THE AFTERNOON (MEAN 900-700 MB RH FALLING TO NEAR 35 PERCENT FAR NORTHWEST AND 65 TO 75 PERCENT SOUTHEAST BY 00Z SUN). SO EXPECT MOSTLY CLOUDY SKIES IN THE MORNING TO PARTIALLY CLEAR FROM NORTHWEST TO SOUTHEAST IN THE AFTERNOON. HIGHS ONLY IN THE LOWER TO MIDDLE 50S. SATURDAY NIGHT...DRIER AIR CONTINUES TO OVERSPREAD THE FORECAST AREA WITH MEAN 900-700 MB RH FALLING TO BETWEEN 25 AND 35 PERCENT LEADING TO MOSTLY CLEAR TO PARTLY CLOUDY SKIES WITH LOWS IN THE LOWER TO MIDDLE 30S. SUNDAY...UPPER LEVEL RIDGING/HEIGHT RISES SHOULD LEAD TO THE DRY AIR HOLDING ON FOR MUCH OF THE DAY YIELDING PARTLY TO MOSTLY SUNNY SKIES. HIGHS A BIT MILDER WITH MIDDLE 50S TO NEAR 60 EXPECTED. MONDAY THROUGH THURSDAY...THIS TIME PERIOD IS WHERE THE MODELS ARE HAVING DIFFICULTY DECIPHERING THE DETAILS. THE CRUX OF THE PROBLEM LIES IN THE HANDLING OF AN UPPER LOW THAT MOVES OUT OF THE SOUTHWESTERN STATES AS THIS SYSTEM IS RUNNING INTO AN OMEGA BLOCK EXTENDING FROM THE EASTERN PLAINS INTO THE WESTERN GREAT LAKES. A MAJORITY OF THE EXTENDED MODELS DO WEAKEN THE UPPER LOW AS IT APPROACHES OUR FORECAST AREA. THE ECMWF IS THE MOST AGGRESSIVE IN THE WEAKENING WHICH APPEARS TO MAKE THE MOST SENSE WHILE THE GFS STILL BRINGS A DECENT AMOUNT OF MOISTURE SEEMINGLY THROUGH THE RIDGE. FOR NOW WILL CONTINUE WITH THE DRY FORECAST BUT CONFIDENCE IS ON THE LOWER SIDE. WILL TRIM BACK HIGHS BY A FEW DEGREES INTO THE SEASONABLE UPPER 50S TO LOWER 60S AS MORE CLOUD COVER IS EXPECTED AT A MINIMUM. SULLIVAN && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
945 PM EDT THU OCT 11 2007 .UPDATE... FCST HAS BEEN UPDATED TO INCLUDE A MENTION OF SNOW OVER THE HIGHER TERRAIN OF NCNTRL UPPER MI. -SHRA HAVE BEEN MIXING WITH SNOW AT TIMES HERE AT THE OFFICE THIS EVENING (FIRST SNOWFLAKES OF THE SEASON OFFICIALLY AT THE OFFICE). IT IS SURPRISING TO SEE SNOW GIVEN EVENING TAMDAR SOUNDING FROM KSAW WHICH SHOWED SHALLOW MOIST LAYER EXTENDING ONLY TO AROUND 870MB OR 4KFT MSL (DWPT DEPRESSION REACHED 40C AT 775MB) WITH TEMP IN THE MOIST LAYER ONLY AS LOW AS -5C. TYPICALLY...THIS IS NOT COLD ENOUGH FOR ICE NUCLEATION TO OCCUR. APPARENTLY THIS IS ONE OF THE RARE CASES WHERE THERE ARE ICE NUCLEI AVBL THAT CAN BE ACTIVATED AT TEMPS MUCH HIGHER THAN -10C (-10C IS THE TEMP OFTEN CONSIDERED NEEDED FOR ACTIVATION OF ICE NUCLEI AND THUS THE GENERATION OF SNOWFLAKES). WILL TAKE ANOTHER LOOK AT MIN TEMPS WHICH MAY NEED TO BE LOWERED IN SOME PLACES AS MORE BREAKS ARE APPEARING IN THE CLOUD COVER. && .SHORT TERM (TONIGHT THROUGH 00Z SAT) ISSUED AT 352 PM EDT... NOT MUCH CHANGE FROM THE PREVIOUS FORECAST AND WILL CONTINUE WITH SOME UPSLOPE DRIZZLE/RAIN AS THE WIND STAYS FROM THE NORTH AND LAKE EFFECT CONTRIBUTIONS ARE SEEN WITH 850 MB TEMPERATURES OF -4C AND LAKE TEMPS FROM 8C TO 10C IS ENOUGH FOR LAKE EFFECT. THIS WILL CONTINUE AS CYCLONIC FLOW CONTINUES THROUGH TOMORROW MORNING AND THEN DRIER AIR FINALLY MOVES IN IN THE AFTERNOON. KEPT CLOSE TO GOING TEMPERATURES. OVERALL...NO REAL BIG CHANGES TO THE GOING FORECAST. .LONG TERM (FRI NIGHT THRU THU)... WILL FOLLOW THE ECMWF AND NCEP ENSEMBLE AS RECOMMENDED BY HPC. THUS THE CLOSED LOW OVER EAST CENTRAL ONTARIO WILL REMAIN STATIONARY AS THE LOW OVER THE OHIO RIVER VALLEY MOVES TO THE EAST COAST FRIDAY NIGHT AND SATURDAY. A SHORTWAVE WRAPPING AROUND THIS LOW WILL SWEEP ACROSS THE EASTERN U.P. THE RIDGE WILL PUSH INTO WESTERN ONTARIO. ANOTHER WEAK SHORTWAVE WORKING THROUGH THE RIDGE WILL SWEEP INTO THE FORECAST AREA SATURDAY AFTERNOON. THE SURFACE HIGH WILL LIKEWISE BE OVER THE AREA. WINDS WILL BE LIGHT. THE HIGH WILL PUSH OFF TO THE EAST ON SATURDAY NIGHT AND SUNDAY. THE SURFACE LOW WILL TRACK INTO KANSAS. AN ACCOMPANYING TROUGH WILL STRETCH INTO THE WESTERN U.P. LATE ON SATURDAY AS A SHORTWAVE MOVE INTO WESTERN U.P. LOW LEVEL MOISTURE WILL WORK INTO WISCONSIN. HOWEVER...THE FORECAST AREA WILL REMAIN DRY. THE SHORTWAVE OVER WESTERN ONTARIO WILL SLIDE INTO SOUTHEAST ONTARIO ON SUNDAY NIGHT WHILE THE RIDGE BUILDS OVER MANITOBA. THE HIGH WILL REMAIN IN PLACE AND BLANKET THE FORECAST AREA THROUGH WEDNESDAY. A CLOSED LOW WILL SHIFT INTO THE KANSAS. THE SURFACE HIGH WILL REMAIN OVER WESTERN ONTARIO AND EXPAND OVER THE FORECAST. MEANWHILE...THE LOW OVER THE TEXAS PANHANDLE WILL SHIFT EAST INTO OKLAHOMA BEFORE WASHING OUT. DEEP MOISTURE WILL SPREAD INTO WISCONSIN ON SUNDAY NIGHT. THE MOISTURE AIR WILL STAY WEST OF THE AREA. UNDER THE INFLUENCE OF THE STABLE HIGH...CONDITIONS SHOULD REMAIN DRY. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... MVFR CIGS WILL CONTINUE TO BE THE RULE THRU THE NIGHT AND INTO THE MORNING HOURS AT KCMX/KSAW. HOWEVER...EXPANSIVE LOW-LEVEL MOISTURE THAT HAS PERSISTED OVER THE UPPER LAKES INTO ONTARIO IS BEGINNING TO MIX OUT AS VIS SATELLITE IMAGERY THRU THE DAY HAS SHOWN CLOUD COVER THINNING OUT SOME...ESPECIALLY UPSTREAM IN ONTARIO. SO...THERE SHOULD BE SOME IMPROVEMENT IN CIGS WITH CONDITIONS GRADUALLY TRENDING TOWARD SCT CLOUD COVER FRI...FIRST AT KCMX EARLY AFTN THEN AT KSAW BY LATE AFTN. IN THE MEANTIME...AIRMASS REMAINS COLD ENOUGH FOR LAKE EFFECT PROCESSES TO CONTRIBUTE TO CLOUD COVER AND SOME LIGHT PCPN AT TIMES...MAINLY AT KSAW UNDER NRLY FLOW. PCPN SHOULD BE CONFINED TO THE EVENING HRS AT KCMX AS SLIGHTLY DRIER AIR IS MAKING INROADS OVER WRN AND NRN LAKE SUPERIOR. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... WINDS ARE COMING DOWN AND DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST. NO GALES FORESEEN. LIGHT WINDS EXPECTED THROUGH THE WEEKEND AS THE HIGH REMAINS OVER THE UPR GREAT LAKES. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...ROLFSON SHORT TERM...GM EXTENDED TERM...DLG AVIATION...ROLFSON MARINE...GM
AREA FORECAST DISCUSSION
NWS GAYLORD MI
800 PM EDT THU OCT 11 2007 .UPDATE...IN LIEU OF ISSUING AN AVIATION DISCUSSION THAT NO ONE IS GOING TO READ...WILL ISSUE AN EARLY UPDATE SINCE HAVE ALREADY MADE CHANGES TO THE GRIDS. SCATTERED SHOWERS HAVE BEEN DEVELOPING EAST OF I-75 THIS EVENING...AS OPPOSED TO WEST OF I-75 WHERE EARLIER SPOTTY PRECIPITATION HAS DISSIPATED. A LITTLE DRIER ALOFT OVER UPPER MI/NORTHWEST LOWER PER RECENT AIRCRAFT SOUNDINGS MAY BE A FACTOR IN THIS. THIS IS NOT LIKELY TO CHANGE OVERNIGHT...THOUGH IT IS GETTING COLDER ALOFT (EARLY PEEK AT INCOMING APX SOUNDING DATA INDICATES 850MB TEMPERATURES DOWN TO -2.5C). HAVE REMOVED SHOWER MENTION FOR NORTHWEST LOWER THIS EVENING...WILL KEEP IT IN OVERNIGHT FOR NOW GIVEN INCREASING OVER WATER INSTABILITY AND RE- EVALUATE THROUGH THE EVENING. HAVE ADDED SHOWERS TO NORTHEAST LOWER GIVEN CURRENT ACTIVITY. HAVE MESSED AROUND WITH CLOUD COVER A BIT AS WELL WITH BREAKS ACROSS PARTS OF EASTERN UPPER AND THE TIP OF THE MITT...COULD END UP BEING THAT AREAS AROUND THE ST. MARY`S RIVER STAY PARTLY CLOUDY OVERNIGHT. WILL BE ISSUING ANOTHER DISCUSSION AROUND 0215Z. NEW GRIDS ALREADY PUBLISHED. JPB && .PREV DISCUSSION... /ISSUED 355 PM EDT THU OCT 11 2007/ WEAK SURFACE TROUGH REMAINS OVER THE WRN GREAT LAKES REGION LATE THIS AFTERNOON. DEPARTING UPPER LOW IS MOVING EAST THRU PENNSYLVANIA...WHILE ANOTHER UPPER LOW IS DROPPING SOUTH FROM JAMES BAY TOWARD LAKE HURON. SKIES REMAIN MOSTLY CLOUDY ACROSS OUR ENTIRE CWA. ERN UPR AND FAR NRN LWR MICHIGAN AWAY FROM PROMINENT LAKE INFLUENCES TRIED TO BREAK OUT OF THE CLOUDS...BUT TO NO AVAIL AS SELF-DESTRUCT SUNSHINE LEAD TO ONLY MORE CLOUD DEVELOPMENT WITH LIMITED LOW LEVEL MOISTURE TRAPPED BELOW THE INVERSION. LAKE EFFECT RAIN SHOWERS...ON THE OTHER HAND...HAVE TENDED TO DIMINISH OVER TIME THIS AFTERNOON AS REMAINING MOISTURE APPEARS TO BE TOO SHALLOW TO SUPPORT SIGNIFICANT PRECIP PRODUCTION DESPITE DELTA T`S IN THE MID TO UPPER TEENS. PRIMARY FORECAST QUESTION OVER THE NEXT 24 HOURS WILL BE POPS...AMOUNT AND COVERAGE...AS THE UPPER LOW TO THE NORTH PLUNGES SOUTH INTO SE ONTARIO. ADDITIONAL CONCERNS WILL BE TEMPS (SPECIFICALLY TEMP PROFILE) AND WINDS (SPEED AND DIRECTION) AS MORE COLD AIR ACCOMPANIES THIS UPPER LOW FEATURE. TONIGHT AND FRIDAY...JAMES BAY LOW WILL STEADILY DROP SOUTH ALONG THE ONTARIO/QUEBEC BORDER TONIGHT AND THEN INTO SE ONTARIO ON FRIDAY. A REINFORCING SHOT OF COLD AIR WILL ACCOMPANY THIS SYSTEM. 850 MB TEMPS DROP TO -3 C BY 12Z FRIDAY AND REMAIN UNCHANGED THROUGHOUT THE DAY. LOW LEVEL WINDS WILL GRADUALLY SHIFT FROM DUE NORTH THIS EVENING TO NORTHWEST BY MIDDAY FRIDAY. MAIN LIMITING FACTOR TO PRECIP PRODUCTION (SYNOPTIC OR LAKE EFFECT) WILL BE SHALLOW AND RATHER SPARSE LOW LEVEL MOISTURE. 900-700 MB RH WILL REMAIN AT AROUND 50-60 PCT THRU FRIDAY...ALTHOUGH A BIT HIGHER (NEAR 70 PCT) FOR NE SECTIONS OF OUR CWA CLOSER TO THE APPROACHING UPPER LOW. A LOOK AT UPSTREAM OBS DOES INDICATE LIGHT RAIN/SNOW SHOWERS OCCURRING ALONG THE SW SIDE OF THE UPPER LOW NORTH OF LAKE SUPERIOR AND SAULT STE MARIE AIDED BY A SHORT WAVE ROTATING AROUND THE UPPER LOW. HOWEVER...THESE AREAS ARE STILL NOT WITHIN THE AREA OF DEEP WRAP-AROUND MOISTURE ASSOCIATED WITH THE LOW CENTER. THIS MOISTURE WILL NOT REACH OUR CWA UNTIL FRIDAY NIGHT. THUS...ANY PRECIP OVER THE NEXT 24 HOURS WILL REMAIN LIGHT AND SPOTTY...WITH FOCUS OF CHANCE POPS SHIFTING FROM N FLOW LOCATIONS THIS EVENING (I.E. THE LEELANAU PENINSULA TO MANISTEE) TO N/NW FLOW LOCATIONS OVERNIGHT (I.E. WEST OF US-131) AND THEN TO NW FLOW AREAS ON FRIDAY (I.E. ALONG AND WEST OF US-131...PRESQUE ISLE TO THUNDER BAY...AND NRN SECTIONS OF CHIPPEWA COUNTY. MODELS SOUNDINGS SHOW ZERO ISOTHERM TRYING TO DROP BELOW 2500 FT...BUT JUST FALLING SHORT. THUS...EXPECT ALL PRECIP SHOULD REMAIN LIQUID. MOST OF OUR NEARSHORE AREAS WILL CONTINUE TO EXPERIENCE WIND GUSTS TO 25 KTS TONIGHT THRU FRIDAY (AT LEAST) AS SURFACE PRESSURE GRADIENT REMAINS TIGHT ON THE BACKSIDE OF THE APPROACHING UPPER LOW. WILL THEREFORE EXTEND SCA`S THRU 00Z SATURDAY. LONGER RANGE FORECAST (FRIDAY NIGHT THROUGH NEXT THURSDAY)...LOTS OF QUESTION MARKS DURING THIS PERIOD AS EXTENDED MODELS OFFER A VARIETY OF SOLUTIONS. IT DOES NOT APPEAR AS THOUGH IT WILL WARM UP THIS WEEKEND AS THE MODELS CONTINUE TO TREND ON THE COOLER SIDE. NEXT WEEK IS WHERE THE MAIN CONCERNS ARE AS MODELS VARY ON THE MOVEMENT/ STRENGTH OF A CUTOFF UPPER LOW PROGRESSING TO THE EAST OUT OF THE SOUTHERN STATES. THE INTERACTION OF THIS SYSTEM WITH AN OMEGA BLOCK HIGH WILL BE THE MAIN FOCUS OF THIS PORTION OF THE PACKAGE. FRIDAY NIGHT...MODELS BRING CUTOFF UPPER LOW CURRENTLY EVIDENT ON WATER VAPOR LOOP NEAR GEORGIAN BAY SOUTHWARD AND EVEN APPEAR TO RETROGRADE THIS FEATURE TO THE WEST JUST A TAD. MEANWHILE...OVER LAKE INSTABILITY CONTINUES WITH DELTA TS REMAINING IN THE MIDDLE TO UPPER TEENS. MOISTURE IS ON THE UPTICK WITH MEAN 900-700 MB RH INCREASING TO BETWEEN 90 AND 95 PERCENT NORTHEAST AND 60 TO 70 PERCENT FAR SOUTH. THEREFORE...CONTINUED CHANCE OF LAKE EFFECT RAIN SHOWERS ACROSS NORTHWEST FLOW AREAS AND ADDED A SLIGHT CHANCE OF SHOWERS ACROSS THE NORTHEAST DUE TO SOME LIMITED SYNOPTIC SUPPORT FROM THE UPPER LOW WHICH INCHES A LITTLE CLOSER. LOWS IN THE MIDDLE TO UPPER 30S. SATURDAY...MODEL SOUNDINGS/CROSS SECTIONS SHOW LOW LEVEL MOISTURE LINGERING IN THE MORNING (MEAN 900-700 MB RH STILL 85 TO 95 PERCENT) BUT SLOWLY DISSIPATING IN THE AFTERNOON (MEAN 900-700 MB RH FALLING TO NEAR 35 PERCENT FAR NORTHWEST AND 65 TO 75 PERCENT SOUTHEAST BY 00Z SUN). SO EXPECT MOSTLY CLOUDY SKIES IN THE MORNING TO PARTIALLY CLEAR FROM NORTHWEST TO SOUTHEAST IN THE AFTERNOON. HIGHS ONLY IN THE LOWER TO MIDDLE 50S. SATURDAY NIGHT...DRIER AIR CONTINUES TO OVERSPREAD THE FORECAST AREA WITH MEAN 900-700 MB RH FALLING TO BETWEEN 25 AND 35 PERCENT LEADING TO MOSTLY CLEAR TO PARTLY CLOUDY SKIES WITH LOWS IN THE LOWER TO MIDDLE 30S. SUNDAY...UPPER LEVEL RIDGING/HEIGHT RISES SHOULD LEAD TO THE DRY AIR HOLDING ON FOR MUCH OF THE DAY YIELDING PARTLY TO MOSTLY SUNNY SKIES. HIGHS A BIT MILDER WITH MIDDLE 50S TO NEAR 60 EXPECTED. MONDAY THROUGH THURSDAY...THIS TIME PERIOD IS WHERE THE MODELS ARE HAVING DIFFICULTY DECIPHERING THE DETAILS. THE CRUX OF THE PROBLEM LIES IN THE HANDLING OF AN UPPER LOW THAT MOVES OUT OF THE SOUTHWESTERN STATES AS THIS SYSTEM IS RUNNING INTO AN OMEGA BLOCK EXTENDING FROM THE EASTERN PLAINS INTO THE WESTERN GREAT LAKES. A MAJORITY OF THE EXTENDED MODELS DO WEAKEN THE UPPER LOW AS IT APPROACHES OUR FORECAST AREA. THE ECMWF IS THE MOST AGGRESSIVE IN THE WEAKENING WHICH APPEARS TO MAKE THE MOST SENSE WHILE THE GFS STILL BRINGS A DECENT AMOUNT OF MOISTURE SEEMINGLY THROUGH THE RIDGE. FOR NOW WILL CONTINUE WITH THE DRY FORECAST BUT CONFIDENCE IS ON THE LOWER SIDE. WILL TRIM BACK HIGHS BY A FEW DEGREES INTO THE SEASONABLE UPPER 50S TO LOWER 60S AS MORE CLOUD COVER IS EXPECTED AT A MINIMUM. SULLIVAN && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
630 AM CDT WED OCT 10 2007 ...UPDATED AVIATION... .DISCUSSION... ACTIVE FALL TRANSITION PATTERN MEANS A PLETHORA OF FORECAST CHALLENGES THIS MORNING. IN THE NEAR TERM...MUCH ADVERTISED BACKDOOR COLD FRONT WAS ANALYZED SOUTH OF THE CWA AT 08Z WITH AGGRESSIVE TEMPERATURE FALLS NOW MOVING INTO FAR NORTHERN MISSOURI WHERE READINGS WERE DROPPING QUICKLY THROUGH THE 40S. 00Z UPPER AIR ANALYSIS DEMONSTRATES THE NEED FOR A DENSER OBSERVATION NETWORK WITH 850MB TEMPS OF +12C AT OMAHA AND -2C AT MINNEAPOLIS. HOWEVER...SEVERAL AMDAR SOUNDINGS TAKEN FROM OMAHA SHOWED AN ELEVATED FRONTAL PASSAGE SHORTLY AFTER 02Z...WHICH AGREES WELL WITH THE PLACEMENT OF THE 850MB THERMAL GRADIENT OFFERED BY THE HI RESOLUTION NAM-WRF. THIS ELEVATED BOUNDARY WILL PROGRESS TO THE S/SW TODAY...CLEARING ALL BY THE FAR SW CWA BY AFTERNOON. ALTHOUGH THE TEMPERATURE FORECAST MAY ERR IN A GIVEN LOCATION...SAW LITTLE NEED TO CHANGE THE GRAPHICALLY DEPICTED GRADIENT OF MID 50S IN NE MO TO THE LOWER 70S FROM BUTLER TO MOUND CITY KS. CLOUD COVER HAS LARGELY BROKEN UP ALONG THE W/SW FRINGES OF THE UPPER LEVEL CIRCULATION ACROSS CENTRAL IA...BUT FEEL THIS IS LARGELY DIURNALLY DRIVEN. FORECAST SOUNDINGS CONTINUE TO SHOW COLD ADVECTION/MOISTENING MAXIMIZED AT 850MB ATOP AMPLE LOW LEVEL INSTABILITY. THEREFORE...THE SMALLER DIURNAL RISE FORECAST OVER NE MO IS BASED ON THE EXPECTATION THAT STRATO-CU WILL REDEVELOP BY MID-LATE MORNING WITH AT LEAST BROKEN COVERAGE. COLD ADVECTION WILL CONTINUE THROUGH MID MORNING THURSDAY BEFORE MID LEVEL INFLECTION POINT IN THE HEIGHT CONTOURS TURNS THE FLOW NEUTRAL. GIVEN COLD OVERNIGHT LOWS IN THE UPPER 30S TO LOWER 40S AND LIMITED MIXING DEPTHS WITHIN THE LOW LEVEL RIDGE AXIS...EVEN THE 20 DEGREE DIURNAL RISE FORECAST MAY BE OPTIMISTIC. STRATO-CU DEVELOPMENT COULD MEAN THE DIFFERENCE BETWEEN MID 50S AND MID 60S...AS SPREAD ACROSS THE OBJECTIVE GUIDANCE. GIVEN THESE UNCERTAINTIES...HAVE SPLIT THE DIFFERENCE FOR NOW. A WEAK SHORTWAVE RIDGE ALOFT WILL ATTEMPT TO PROGRESS TOWARD THE REGION ON FRIDAY...BUT LIGHT E/SE LOW LEVEL FLOW TRAJECTORIES OFFER LITTLE IN THE WAY OF A WARMUP...MAYBE ON THE ORDER OF 5 DEGREES OR SO. FOR THE WEEKEND...DISCUSSION AMONG SURROUNDING WFOS CONCLUDED THAT TRENDS WERE SUPPORTED ENOUGH TO WARRANT CHANGES TO THE DAY 4-5 PERIOD OF THE FORECAST. POWERFUL STORM SYSTEM RAPIDLY ADVANCING ACROSS THE NORTHERN PACIFIC TO 45N/150W WILL DIG TOWARD THE GREAT BASIN BY SATURDAY. ALTHOUGH LARGE SCALE BLOCK ESTABLISHED BY GREAT LAKES CUTOFF MAY CONTINUE TO SLOW THE EASTWARD EVOLUTION OF THIS SYSTEM LATER IN THE WEEKEND...SUFFICIENT PROGRESSION SHOULD OCCUR SUCH THAT WE`LL SEE THE UPPER SHORTWAVE RIDGE AXIS SLIDE EAST OF THE REGION ON SATURDAY MORNING. IN RESPONSE TO MODEST HEIGHT FALLS...SURFACE CYCLOGENESIS OVER THE WESTERN PLAINS WILL PROMOTE WARM FRONTOGENESIS OVER ERN KS/WRN MO. STRONGLY VEERING FLOW WITH HEIGHT...WITH MOIST SOUTHWEST FLOW ALOFT...WILL YIELD A BROAD WARM ADVECTION REGIME WITH AMPLE MID LEVEL ISENTROPIC ASCENT/ FRONTOGENETIC FORCING. THUS EXPECT A BROAD COVERAGE/LOW QPF EVENT TO UNFOLD FROM SW TO NE ON SATURDAY AS BAROCLINIC ZONE BECOMES ESTABLISHED AND SLOWLY RETREATS NORTHWARD. DID NOT MAKE ANY CHANGES FOR SUNDAY AND EARLY NEXT WEEK...BUT IT WOULD APPEAR THAT MOST OF THE CWA WILL SEE A BREAK IN THE PRECIP ON SUNDAY AS MILD/HUMID/BREEZY CONDITIONS ARE BROUGHT IN WITH THE SURFACE WARM SECTOR. WIDESPREAD PRECIP EVENT STILL LOOKS LIKELY SUNDAY NIGHT...POSSIBLY LASTING UP TO 48 HOURS AS UPPER TROUGH IS SLOWED BY EASTERN BLOCK. LOOKING FURTHER AHEAD...NORTHERN HEMISPHERIC WATER VAPOR SHOWS THIS SYSTEM AS THE FIRST IN A SERIES OF PACIFIC WAVES ONCE THE PATTERN CHANGE IS COMPLETED...SUGGESTING THAT WE MAY BE ENTERING A FAVORABLE PERIOD FOR PRECIPITATION CHANCES. BOOKBINDER && .AVIATION... COOL DRY AIR CONTINUES TO ADVECT OVER TERMINALS THIS MORNING UNDER CLR SKIES...YIELDING WIDESPREAD VFR CONDITIONS. WINDS WILL INCREASE OUT OF THE NW TOWARDS LATE MORNING...AND EXPECT CIGS OVR IOWA TO REMAIN NORTHEAST OF TERMINAL APPROACHES. WILL NEED TO WATCH FOR THE POSSIBILITY OF MORE EXTENSIVE MVFR VSBY EARLY THU MORNING...BUT FOR NOW HAVE ONLY INCLUDED REDUCTIONS AT THE FAVORED KSTJ RIVER VALLEY SITE. 21 && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
348 AM CDT WED OCT 10 2007 .DISCUSSION... ACTIVE FALL TRANSITION PATTERN MEANS A PLETHORA OF FORECAST CHALLENGES THIS MORNING. IN THE NEAR TERM...MUCH ADVERTISED BACKDOOR COLD FRONT WAS ANALYZED SOUTH OF THE CWA AT 08Z WITH AGGRESSIVE TEMPERATURE FALLS NOW MOVING INTO FAR NORTHERN MISSOURI WHERE READINGS WERE DROPPING QUICKLY THROUGH THE 40S. 00Z UPPER AIR ANALYSIS DEMONSTRATES THE NEED FOR A DENSER OBSERVATION NETWORK WITH 850MB TEMPS OF +12C AT OMAHA AND -2C AT MINNEAPOLIS. HOWEVER...SEVERAL AMDAR SOUNDINGS TAKEN FROM OMAHA SHOWED AN ELEVATED FRONTAL PASSAGE SHORTLY AFTER 02Z...WHICH AGREES WELL WITH THE PLACEMENT OF THE 850MB THERMAL GRADIENT OFFERED BY THE HI RESOLUTION NAM-WRF. THIS ELEVATED BOUNDARY WILL PROGRESS TO THE S/SW TODAY...CLEARING ALL BY THE FAR SW CWA BY AFTERNOON. ALTHOUGH THE TEMPERATURE FORECAST MAY ERR IN A GIVEN LOCATION...SAW LITTLE NEED TO CHANGE THE GRAPHICALLY DEPICTED GRADIENT OF MID 50S IN NE MO TO THE LOWER 70S FROM BUTLER TO MOUND CITY KS. CLOUD COVER HAS LARGELY BROKEN UP ALONG THE W/SW FRINGES OF THE UPPER LEVEL CIRCULATION ACROSS CENTRAL IA...BUT FEEL THIS IS LARGELY DIURNALLY DRIVEN. FORECAST SOUNDINGS CONTINUE TO SHOW COLD ADVECTION/MOISTENING MAXIMIZED AT 850MB ATOP AMPLE LOW LEVEL INSTABILITY. THEREFORE...THE SMALLER DIURNAL RISE FORECAST OVER NE MO IS BASED ON THE EXPECTATION THAT STRATO-CU WILL REDEVELOP BY MID-LATE MORNING WITH AT LEAST BROKEN COVERAGE. COLD ADVECTION WILL CONTINUE THROUGH MID MORNING THURSDAY BEFORE MID LEVEL INFLECTION POINT IN THE HEIGHT CONTOURS TURNS THE FLOW NEUTRAL. GIVEN COLD OVERNIGHT LOWS IN THE UPPER 30S TO LOWER 40S AND LIMITED MIXING DEPTHS WITHIN THE LOW LEVEL RIDGE AXIS...EVEN THE 20 DEGREE DIURNAL RISE FORECAST MAY BE OPTIMISTIC. STRATO-CU DEVELOPMENT COULD MEAN THE DIFFERENCE BETWEEN MID 50S AND MID 60S...AS SPREAD ACROSS THE OBJECTIVE GUIDANCE. GIVEN THESE UNCERTAINTIES...HAVE SPLIT THE DIFFERENCE FOR NOW. A WEAK SHORTWAVE RIDGE ALOFT WILL ATTEMPT TO PROGRESS TOWARD THE REGION ON FRIDAY...BUT LIGHT E/SE LOW LEVEL FLOW TRAJECTORIES OFFER LITTLE IN THE WAY OF A WARMUP...MAYBE ON THE ORDER OF 5 DEGREES OR SO. FOR THE WEEKEND...DISCUSSION AMONG SURROUNDING WFOS CONCLUDED THAT TRENDS WERE SUPPORTED ENOUGH TO WARRANT CHANGES TO THE DAY 4-5 PERIOD OF THE FORECAST. POWERFUL STORM SYSTEM RAPIDLY ADVANCING ACROSS THE NORTHERN PACIFIC TO 45N/150W WILL DIG TOWARD THE GREAT BASIN BY SATURDAY. ALTHOUGH LARGE SCALE BLOCK ESTABLISHED BY GREAT LAKES CUTOFF MAY CONTINUE TO SLOW THE EASTWARD EVOLUTION OF THIS SYSTEM LATER IN THE WEEKEND...SUFFICIENT PROGRESSION SHOULD OCCUR SUCH THAT WE`LL SEE THE UPPER SHORTWAVE RIDGE AXIS SLIDE EAST OF THE REGION ON SATURDAY MORNING. IN RESPONSE TO MODEST HEIGHT FALLS...SURFACE CYCLOGENESIS OVER THE WESTERN PLAINS WILL PROMOTE WARM FRONTOGENESIS OVER ERN KS/WRN MO. STRONGLY VEERING FLOW WITH HEIGHT...WITH MOIST SOUTHWEST FLOW ALOFT...WILL YIELD A BROAD WARM ADVECTION REGIME WITH AMPLE MID LEVEL ISENTROPIC ASCENT/ FRONTOGENETIC FORCING. THUS EXPECT A BROAD COVERAGE/LOW QPF EVENT TO UNFOLD FROM SW TO NE ON SATURDAY AS BAROCLINIC ZONE BECOMES ESTABLISHED AND SLOWLY RETREATS NORTHWARD. DID NOT MAKE ANY CHANGES FOR SUNDAY AND EARLY NEXT WEEK...BUT IT WOULD APPEAR THAT MOST OF THE CWA WILL SEE A BREAK IN THE PRECIP ON SUNDAY AS MILD/HUMID/BREEZY CONDITIONS ARE BROUGHT IN WITH THE SURFACE WARM SECTOR. WIDESPREAD PRECIP EVENT STILL LOOKS LIKELY SUNDAY NIGHT...POSSIBLY LASTING UP TO 48 HOURS AS UPPER TROUGH IS SLOWED BY EASTERN BLOCK. LOOKING FURTHER AHEAD...NORTHERN HEMISPHERIC WATER VAPOR SHOWS THIS SYSTEM AS THE FIRST IN A SERIES OF PACIFIC WAVES ONCE THE PATTERN CHANGE IS COMPLETED...SUGGESTING THAT WE MAY BE ENTERING A FAVORABLE PERIOD FOR PRECIPITATION CHANCES. BOOKBINDER && .AVIATION... FOR THE 06Z TAFS...CLEAR SKIES THROUGH WEDNESDAY EVENING AS A COOL AND DRY AIR MASS WILL BE FIRMLY ENTRENCHED ACROSS MISSOURI. NORTHERLY WINDS COULD BECOME A BIT GUSTY WEDNESDAY AFTERNOON BUT WILL QUICKLY SUBSIDE AN HOUR OR TWO PRIOR TO SUNSET. MJ && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
340 PM EDT WED OCT 10 2007 .SYNOPSIS... RELATIVELY CLOUDY BUT QUIET WEATHER IS EXPECTED TONIGHT. AREAS OF LOW CLOUDS AND DRIZZLE ARE EXPECTED TO DEVELOP ALONG AND EAST OF THE GREEN MOUNTAINS OVERNIGHT. THE WEATHER IS EXPECTED TO BEGIN TO DETERIORATE BEGINNING THURSDAY AS A STRONG AREA OF LOW PRESSURE MOVES CLOSER TO THE REGION. RAIN WILL DEVELOP FROM WEST TO EAST DURING THE DAY...WITH A WIDESPREAD SOAKING RAINFALL AREA WIDE THURSDAY NIGHT. AS THE LOW PRESSURE MOVES NORTHEAST OF THE AREA FRIDAY...THE RAINFALL WILL SLOWLY TAPER OFF...LINGERING LONGEST ACROSS NORTHERN AREAS. COLDER AIR WILL FILTER IN FRIDAY NIGHT AND SATURDAY. A SECONDARY LOW PRESSURE AREA WILL MOVE ACROSS THE REGION SATURDAY...BRINGING THE POTENTIAL FOR SOME SNOW SHOWERS AT HIGHER ELEVATIONS OF THE ADIRONDACKS AND GREEN MOUNTAINS. && .NEAR TERM /THROUGH TONIGHT/... UPDATED 340 PM WEDNESDAY REGION WILL BE BETWEEN A COUPLE OF SYSTEMS...ONE TO THE SOUTHEAST THE OTHER TO THE SOUTHWEST. CONSIDERABLE LOW LEVEL MOISTURE WE HAVE WONT GO ANYWHERE...AND WITH A LIGHT EASTERLY FLOW...ADDITIONAL ATLANTIC MOISTURE WILL WORK ITS WAY THIS-A-WAY. THIS SHOULD LEAD TO FAIRLY WIDESPREAD LOW CLOUDS AND DRIZZLE ALONG AND EAST OF THE GREEN MOUNTAINS LATER TONIGHT. OTHERWISE...WAY OUT WEST IN THE ST LAWERENCE VALLEY...WE COULD SEE SOME SHOWERS BREAKING OUT LATE TONIGHT AS THE NEXT STORM SYSTEM BEGINS TO APPROACH. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS THE EXTENSIVE CLOUD COVER WILL KEEP TEMPS ONLY BOTTOMING OUT IN THE MID 40S TO LOW 50S. && .SHORT TERM /THURSDAY THROUGH SATURDAY/... UPDATED 340 PM WEDNESDAY NO CHANGES IN THE OVERALL FORECAST PHILOSPHY AS WE ENTER A RATHER ACTIVE PERIOD WITH TWO SYSTEMS EXPECTED TO IMPACT THE AREA. THE FIRST SYSTEM IS THE BIG UPPER LOW CLEARLY VISIBLE OVER THE ERN GREAT LAKES. THIS LOW WILL TREK EAST AND INDUCE SURFACE CYCLOGENSIS JUST OFF THE MID ATLANTIC COAST LATE TONIGHT. AS THIS HAPPENS...LOW AND MID LEVEL SOUTH-SOUTHEAST FLOW WILL DEVELOP...HELPING TO ADVECT ADDITIONAL ATLANTIC MOISTURE OUR WAY. WITH STRONG UPPER LEVEL DYNAMICS AND DIFFLUENCE ALOFT...WE SHOULD SEE WIDESPREAD RAINFALL DEVELOP THURSDAY NIGHT...LASTING INTO THE FIRST PART OF FRIDAY. VERY COMPLEX SYNOPTIC SCENARIO WILL EVOLVE AS THE LOW PRESSURE OCCLUDES. THAT MEANS THERE WILL BE SOME SORT OF DRY SLOT THAT WILL FORM...BUT EXACTLY WHERE OR WHEN IS PRETTY DIFFICULT. ALTHOUGH THE MODELS ARE IN GENERAL ACREEMENT TO THE BIG PICTURE...ITS THE DETAILS THAT WILL BE THE KEYS. SO BEST GUESS RIGHT NOW FOR RAIN AMOUNTS ARE 1 TO 1.5 INCHES ACROSS THE DACKS AND NRN NY...WITH AMOUNTS OF .5 TO 1 INCH ACROSS VERMONT. OROGRAPHICS WILL ALSO LIKELY PLAY A ROLE. RIGHT NOW IT DOESNT APPEAR THAT THIS RAIN WILL CAUSE ANY FLOODING PROBLEMS...AS IT IS EXPECTED TO OCCUR OVER AN 18 HOUR PERIOD. THAT LOW WILL MOVE NORTHEAST AND AWAY FROM HERE ON FRIDAY. AS IT DOES SO...WINDS WILL SWITCH AROUND TO WESTERLY BRINGING IN SOME COOLER AND DRIER AIR. THERE MAY BE ENOUGH LOW LEVEL MOISTURE THAT A SCATTERED SHOWER COULD OCCUR FRIDAY NIGHT...ESPECIALLY ON THE WINDWARD OR UPSLOPE SIDES OF THE MOUNTAINS. GIVEN THE COOLER TEMPS...A STRAY SNOW FLAKE IS POSSIBLE...SO FOR CONTINUITY HAVE LEFT IN MENTION OF SNOW SHOWERS FRIDAY NIGHT FOR SOME OF THE HIGHER TERRAIN ALTHOUGH CONFIDENCE IS QUITE LOW ON THIS. A SECONDARY UPPER LEVEL LOW WILL BE FORMING OVER NRN QUEBEC IN THE LONGWAVE TROUGH AND DROPPING SOUTHWARD AND ACROSS THE AREA ON SATURDAY. THIS UPPER LOW WILL BE ACCOMPANIED BY SOME DECENT COLD AIR ALOFT AND PRETTY STRONG DYNAMICS...SO ALTHOUGH THE AIRMASS WILL INITIALLY BE DRY...WE SHOULD SEE PRECIP BREAK OUT DURING THE DAY. IF THE MODELS ARE CLOSE TO CORRECT...THIS COULD BE AN INTERESTING DAY WITH A FIRST COATING OF SNOW...PRIMARLY AT ELEVATIONS ABOVE 1500 TO 2000FT. ALTHOUGH WE WILL HAVE DAYTIME HEATING WORKING AGAINST ANY OF THE WHITE STUFF...EVAPORATIONAL COOLING FROM THE INITIALLY DRY AIR AND DYNAMIC COOLING DURING ANY HEAVIER PRECIP SHOULD RESULT IN A TURNOVER TO SOME SNOW...AGAIN MAINLY AT HIGHER ELEVATIONS. PROBABLY NOT ENOUGH TO BREAK OUT THE SKIS JUST YET THOUGH. TEMPERATURES ON SATURDAY WILL OBVIOUSLY BE BELOW NORMAL. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... UPDATED 1141 AM EDT WEDNESDAY SATURDAY NGT INTO MONDAY...CWA STILL UNDER INFLUENCE OF UPPER TROUGH. SYSTEM WILL CONTINUE TO PUSH EAST AWAY FROM THE AREA DURING THIS TIME AS SFC RIDGE BUILDS INTO THE REGION FOR TUES/WED. MAIN MOISTURE FOR THIS TIME FRAME WILL BE WRAP-AROUND RW...W/ A RW/SW MIX MAINLY AT NGT AND OVER HIR ELEV(NORTHERN CWA). REMNANTS OF PRECIP LINGER OVER NE VT BFR LIFTING E INTO THE CANADIAN MARITIMES. 850MB TEMPS FROM SAT NGT INTO MON MORNING RANGE FROM -2C TO -5/-6C...WHICH WOULD BE CD ENOUGH TO SUPPORT AT LEAST A MIX OF RW/SW. CURRENT FORECAST CURRENTLY SHOWS THIS SO WILL STAY CLOSE TO THIS...W/ ADJUSTMENTS FROM THE LATEST HPC GUIDANCE. TEMPS CLOSE TO MDL GUIDANCE W/ CD POOL OF AIR REMAINING OVER THE REGION FOR THE WEEKEND. HAVE KEPT TUES INTO WED MAINLY PRECIP FREE AS RIDGE BUILDS OVER THE CWA. EXTREME NE VT COULD STILL SEE SOME LINGERING RW/SW IN THE MORNING...BFR RIDGE FULLY IN PLACE. EXPECTING CLDS TO LINGER SOMEWHAT INTO TUES FOR MUCH OF THE CWA W/ NNW FLOW AHEAD OF RIDGE. && .AVIATION /18Z WEDNESDAY THROUGH SUNDAY/... UPDATED 130 PM EDT WEDNESDAY THROUGH 18Z THURSDAY...CONDITIONS OVER NORTHERN NY...KSLK KPBG AND KMSS...IMPROVED THIS AFTERNOON AS DRIER AIR ADVECTING IN FROM SOUTHWEST AND WEAK RIDGING OVERHEAD. IN VT...MARINE LAYER INFLUENCE OFF THE ATLANTIC IN WEAK SOUTHEASTERLY FLOW FELT...WITH CONTINUED MVFR CIGS. LOW PRESSURE AREA MOVING UP COAST WILL CONTINUE TONIGHT AS GREATLAKES LOW DIVES SOUTHEAST. THIS WILL TURN MOST LOW LEVEL FLOW TO THE SOUTHEAST...AND EXPECT THE MARINE LAYER AIR TO PUSH WESTWARD. RESULT WILL BE LOWERING CEILINGS AND VISIBILITY TO IFR CATEGORY ALL TAF SITES. SOME -DZ POSSIBLE ESPECIALLY AT KMPV/KSLK. NOT EXPECTING LIFR FOR THE MOST PART AS THIS IS DUE MORE TO THE LOW LEVEL MOISTURE RATHER THAN TYPICAL RADIATIONAL FOG/VV SCENARIO. CONDITIONS TO IMPROVE TO MVFR 14-15Z. 18Z THURSDAY THROUGH MONDAY...MVFR CONDITIONS AT BEST EXPECTED THROUGH THE WEEKEND...THEN SLOWLY IMPROVING CONDITIONS BY SUNDAY. THE LARGE SLOW MOVING UPPER LOW PRESSURE SYSTEM OVER THE OHIO VALLEY AT MID WEEK WILL BEGIN TO INTERACT WITH A NORTHERN STREAM LOW PRESSURE SYSTEM...AND MOVE NORTHEAST OVER THE FORECAST AREA TOWARDS WEEKS END. VERY COLD POOL OF AIR ALOFT WILL CROSS THE AREA ON SATURDAY. AS THE LOW APPROACHES THU/FRI/SAT EXPECT WIDESPREAD LOWERING CIGS/VIS TO MVFR AND IFR. PRECIPITATION TO BECOME MORE SHOWERY SATURDAY INTO SUNDAY AS THE LOW CROSSES OVERHEAD AND MOVES ON NORTHEAST TO THE CANANDIAN MARITIMES. COLDER AIR WRAPPING AROUND BACK SIDE OF LOW WILL BRING -SHRASN TO HIGHER ELEVATIONS MAINLY SATURDAY NIGHT...AND LOW LEVEL AIRCRAFT ICING COULD BE A CONCERN AS WELL. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...NASH NEAR TERM...NASH SHORT TERM...NASH LONG TERM...JN AVIATION...HANSON
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
130 PM EDT WED OCT 10 2007 .SYNOPSIS... OTHER THAN DRIZZLE EAST OF THE GREEN MOUNTAINS...DRY WEATHER IS EXPECTED ACROSS THE NORTH COUNTRY TODAY THROUGH THE FIRST PART OF THE NIGHT. AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL DEVELOP OVER THE AREA ON THURSDAY WHILE A SURFACE LOW PRESSURE SYSTEM MOVES OF THE EASTERN SEABOARD. THESE FEATURES WILL HELP PRODUCE WIDESPREAD RAIN THURSDAY NIGHT AND FRIDAY. COLDER AIR WILL MOVE INTO THE REGION FRIDAY NIGHT AND SATURDAY...HELPING TO PRODUCE RAIN SHOWERS AT THE LOWER ELEVATIONS AND SNOW SHOWERS OVER THE MOUNTAINS. && .NEAR TERM /THROUGH TONIGHT/... THE NORTH COUNTRY WL MAINLY LIE BTWN SYSTEMS THRU THIS PERIOD WITH THE CLOSED GRT LAKES SYSTEM BEGINNING TO INFLUENCE A TAD TOWARD THU MRNG. MEANWHILE...SOME S/W RIDGING AND DRY SLOT WL ALLOW FOR SOME SS ACRS FA BUT INSTABILITY WL ALLOW FOR ANY DAYTIME HEATING TO QUICKLY REDEVLOP CLDS. LLVL INVERSION AND LIGHT ESE FLOW WL LKLY KEEP GREATEST CLDS ACRS ERN VT AND NRN ST LWRNC VLY. MEANWHILE...BEST SS ERLY AACRS ADRNDKS EXPANDING W AND E WITH DAYTIME HEATING/MIXING AS DEPTH OF LLVL MOISTURE DECREASES WITH TIME. AGAIN...ENUF LLVL INSTABILITY WL STL ALLOW FOR REDVLPG CU. AS PRVS FCST SUGGESTED...TMPS SMLR TO TUE BUT HV INCHED UPWARDS A TAD FM PRVS FCST FOR A FEW ZONES. ECONDARY UPPER LEVEL TROUGH MOVING TOWARD THE REGION FROM THE NORTHWEST COULD HELP TOUCH OFF A FEW SHOWERS AND HAVE MENTIONED A SLIGHT CHANCE AFTER MIDNIGHT. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... ACTIVE WEATHER IS EXPECTED DURING THIS PERIOD AS UPPER LEVEL TROUGH APPROACHES THE REGION FROM THE NORTHWEST AND FORCES UPPER LOW SOUTH OF THE REGION TO MOVE NORTHEAST. SURFACE CYCLOGENESIS TO TAKE PLACE AND COMBINED WITH UPPER TROUGH...SHOULD HELP GENERATE FAIRLY WIDESPREAD RAINS ACROSS THE AREA THURSDAY NIGHT AND FRIDAY. THE PRECIPITATION WILL BEGIN TO END FROM SOUTH TO NORTH FRIDAY NIGHT AS SURFACE LOW MOVES FAR ENOUGH AWAY FROM THE REGION. HOWEVER...UPPER TROUGH TO REMAIN OVER THE REGION AND COLD AIR ADVECTION WILL HELP TO LOWER THE SNOW LEVEL TO AROUND 1500 FEET. WILL MENTION A CHANCE OF RAIN OR SNOW SHOWERS ABOVE 1500 FEET...WHICH GOING FORECAST ALREADY HAS COVERED WELL. HIGH TEMPERATURES THROUGH THIS PERIOD WILL BE AT OR BELOW SEASONAL NORMALS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... UPDATED 1141 AM EDT WEDNESDAY SATURDAY NGT INTO MONDAY...CWA STILL UNDER INFLUENCE OF UPPER TROUGH. SYSTEM WILL CONTINUE TO PUSH EAST AWAY FROM THE AREA DURING THIS TIME AS SFC RIDGE BUILDS INTO THE REGION FOR TUES/WED. MAIN MOISTURE FOR THIS TIME FRAME WILL BE WRAP-AROUND RW...W/ A RW/SW MIX MAINLY AT NGT AND OVER HIR ELEV(NORTHERN CWA). REMNANTS OF PRECIP LINGER OVER NE VT BFR LIFTING E INTO THE CANADIAN MARITIMES. 850MB TEMPS FROM SAT NGT INTO MON MORNING RANGE FROM -2C TO -5/-6C...WHICH WOULD BE CD ENOUGH TO SUPPORT AT LEAST A MIX OF RW/SW. CURRENT FORECAST CURRENTLY SHOWS THIS SO WILL STAY CLOSE TO THIS...W/ ADJUSTMENTS FROM THE LATEST HPC GUIDANCE. TEMPS CLOSE TO MDL GUIDANCE W/ CD POOL OF AIR REMAINING OVER THE REGION FOR THE WEEKEND. HAVE KEPT TUES INTO WED MAINLY PRECIP FREE AS RIDGE BUILDS OVER THE CWA. EXTREME NE VT COULD STILL SEE SOME LINGERING RW/SW IN THE MORNING...BFR RIDGE FULLY IN PLACE. EXPECTING CLDS TO LINGER SOMEWHAT INTO TUES FOR MUCH OF THE CWA W/ NNW FLOW AHEAD OF RIDGE. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... UPDATED 130 PM EDT WEDNESDAY THROUGH 18Z THURSDAY...CONDITIONS OVER NORTHERN NY...KSLK KPBG AND KMSS...IMPROVED THIS AFTERNOON AS DRIER AIR ADVECTING IN FROM SOUTHWEST AND WEAK RIDGING OVERHEAD. IN VT...MARINE LAYER INFLUENCE OFF THE ATLANTIC IN WEAK SOUTHEASTERLY FLOW FELT...WITH CONTINUED MVFR CIGS. LOW PRESSURE AREA MOVING UP COAST WILL CONTINUE TONIGHT AS GREATLAKES LOW DIVES SOUTHEAST. THIS WILL TURN MOST LOW LEVEL FLOW TO THE SOUTHEAST...AND EXPECT THE MARINE LAYER AIR TO PUSH WESTWARD. RESULT WILL BE LOWERING CEILINGS AND VISIBILITY TO IFR CATEGORY ALL TAF SITES. SOME -DZ POSSIBLE ESPECIALLY AT KMPV/KSLK. NOT EXPECTING LIFR FOR THE MOST PART AS THIS IS DUE MORE TO THE LOW LEVEL MOISTURE RATHER THAN TYPICAL RADIATIONAL FOG/VV SCENARIO. CONDITIONS TO IMPROVE TO MVFR 14-15Z. 18Z THURSDAY THROUGH MONDAY...MVFR CONDITIONS AT BEST EXPECTED THROUGH THE WEEKEND...THEN SLOWLY IMPROVING CONDITIONS BY SUNDAY. THE LARGE SLOW MOVING UPPER LOW PRESSURE SYSTEM OVER THE OHIO VALLEY AT MID WEEK WILL BEGIN TO INTERACT WITH A NORTHERN STREAM LOW PRESSURE SYSTEM...AND MOVE NORTHEAST OVER THE FORECAST AREA TOWARDS WEEKS END. VERY COLD POOL OF AIR ALOFT WILL CROSS THE AREA ON SATURDAY. AS THE LOW APPROACHES THU/FRI/SAT EXPECT WIDESPREAD LOWERING CIGS/VIS TO MVFR AND IFR. PRECIPITATION TO BECOME MORE SHOWERY SATURDAY INTO SUNDAY AS THE LOW CROSSES OVERHEAD AND MOVES ON NORTHEAST TO THE CANANDIAN MARITIMES. COLDER AIR WRAPPING AROUND BACK SIDE OF LOW WILL BRING -SHRASN TO HIGHER ELEVATIONS MAINLY SATURDAY NIGHT...AND LOW LEVEL AIRCRAFT ICING COULD BE A CONCERN AS WELL. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...EVENSON NEAR TERM...SLW/EVENSON SHORT TERM...EVENSON LONG TERM...JN AVIATION...JAN
AREA FORECAST DISCUSSION...UPDATED
NWS MORRISTOWN TN
945 AM EDT WED OCT 10 2007 .DISCUSSION... DENSE FOG CONTINUES TO COVER MUCH OF SW VA...NE TN...AND THE CENTRAL TN VALLEY THIS MORNING. ACARS SOUNDING FROM TYS SHOWS THE INVERSION EXTENDS FROM THE SURFACE TO 1000 FT AGL...SO IT WILL TAKE SOME TIME FOR THE FOG TO COMPLETELY DISSIPATE. SOME FOG MAY REMAIN UNTIL NOON...BUT WILL ALLOW THE ADVISORY TO EXPIRE AT 10 AM AND COVER THE REMAINING FOG WITH NOWCASTS. THE REST OF THE FORECAST LOOKS GOOD...WITH HIGH TEMPS IN THE UPPER 70S TO LOWER 80S IN MOST SPOTS OUTSIDE THE MOUNTAINS. UPDATE WILL ONLY BE NEEDED TO REMOVE DENSE FOG ADVISORY. && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DGS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
400 AM EDT FRI OCT 12 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF OVER ERN CANADA WITH PAIR OF CLOSED LO CENTERS JUST S OF JAMES BAY MOVING SSW AND THE OTHER OVER THE MID ATLANTIC STATES MOVG E TENDING TO SPIN ARND EACH OTHER WITHIN THE AREA OF LOWER HGTS. THERE IS A SHARP GRADIENT OF H85-7 MSTR ON THE WRN FLANK OF THIS TROF AND TO THE E OF RDG AXIS EXTENDING FM WRN HUDSON BAY INTO THE UPR MS RIVER VALLEY. ALTHOUGH THE UPR LO NEAR JAMES BAY APPEARS TO BE MOVING JUST A BIT W OF DUE S...WV IMAGERY INDICATES DEEPER MSTR ON ITS NW FLANK IS TENDING TO PUSH MORE TO THE W ACRS NCNTRL ONTARIO. EVEN THOUGH THE DEEPER MSTR IS CURRENTLY TO THE E...QUITE A BIT OF SC NOTED IN THE LLVL NLY FLOW BTWN SFC RDG AXIS OVER WRN LK SUP AND LO PRES TO THE E. 00Z TAMDAR SDNG SHOWS QUITE A BIT OF LLVL MSTR TRAPPED BLO SHARP INVRN ARND H85...MARKING THE SUBSIDENCE INVRN ABV LLVL THERMAL TROFFING. SCT LK EFFECT SHRA ARE MOST PERSISTENT OVER THE NCNTRL ZNS WHERE LLVL NLY FLOW IS UPSLOPING. EVEN THOUGH THE LOWEST TEMP AT THE INVRN BASE IS ONLY -6C...NOT TYPICALLY LO ENUF TO SUPPORT ICE NUCLEATION...SOME SN HAS MIXED IN WITH THE RA SINCE LAST EVNG OVER THE HIER TERRAIN. MORE BRKS IN THE CLD NOTED OVER THE SCNTRL WHERE LLVL FLOW IS DOWNSLOPING AND OVER THE W...CLOSER TO THE RDG AXIS AND DRIER LLVL AIR SHOWN ON THE 00Z YPL/INL RAOBS. ANOTHER SHRTWV OVER SCNTRL CAN IS LIFTING NEWD OVER RDG AXIS JUST TO THE W OF THE CWA AND BRINGING A BAND OF CLD/SHRA AS FAR E AS WRN MN. MAIN FCST CONCERNS THIS PACKAGE ARE CLD TRENDS/SHRA CHCS IN NNW FLOW THAT IS FCST TO PERSIST BTWN RDG TO THE W AND AREA OF LOWER HGTS TO THE E. ONE CHALLENGE WL BE DETERMINING WHETHER ANY DEEPER MSTR TO THE E ASSOCIATED WITH UPR LO JUST S OF JAMES BAY CAN ROTATE FAR ENUF TO THE W TO BRING ANY ENHANCEMENT TO THE LK EFFECT SHRA OVER LK SUP. BOTH THE GFS/NAM HAVE TRENDED STEADILY WWD WITH TRACK/POSITION OF UPR LO S OF JAMES BAY MOVING TO THE SSW. THE 00Z NAM SHOWS THE HIER H7 RH BACKING INTO THE E HALF OF LK SUP BY 00Z THIS EVNG BUT REMAINING JUST TO THE NE OF THE LAND CWA THRU THAT TIME. AT THE SAME TIME...MODEL SHOWS THE LLVL FLOW BACKING MORE NW THRU THE DAY AS A SFC HI CENTER BLDS INTO WI. THIS CHANGE IN FLOW SHOULD ALLOW MORE CLRG OVER THE NCNTRL ZNS AS FLOW OFF LK SUP BECOMES LESS FVRBL BUT MORE CLD OVER THE E. HOWEVER...ANY PCPN SHOULD TEND TO DIMINISH WITH DIURNAL HTG TENDING TO DISRUPT ANY LK EFFECT PCPN AND LOWERING LLVL RH WITH INFUSION OF DRIER AIR FM THE NW/INSOLATION. MIXING TO H85 OR SO ON NAM FCST SDNGS YIELDS HI TEMPS ARND 45 OVER THE HIER TERRAIN OF THE NW TO THE LO 50S OVER THE SCNTRL ARND MNM. TNGT...NAM IS MORE AGGRESSIVE AT BACKING MORE SUBSTANTIAL MSTR SWWD THAN THE GFS. CONSIDERING RECENT MODEL TRENDS IN HI AMPLITUDE BLOCKING PATTERN AS WELL AS WV IMAGERY SHOWING DEEPER MSTR BACKING FARTHER W...WL TEND TOWARD THE NAM FCST SCENARIO. NAM EVEN GENERATES SOME LGT PCPN OVER THE ERN ZNS WHERE LLVL CYC NW FLOW WL HAVE A LONGER FETCH ACRS THE ERN LK IN PRESENCE OF H85 THERMAL TROFFING. ADDED CHC POPS FOR THESE LK EFFECT SHRA OVER AREAS NR LK SUP E OF MUNISING AFT MIDNGT WHEN DEEPER MSTR ARRIVES. TENDED TOWARD THE HIER ETA MOS FOR THE ERN ZNS BUT TOWARD THE LOWER GFS MOS FOR THE INTERIOR W...WHERE SKIES ARE LIKELY TO REMAIN MOCLR IN PRESENCE OF PWAT BTWN 0.25 AND 0.50 INCH. TENDED TOWARD THE SLOWER NAM AGAIN ON SAT WITH MORE MSTR/CLDS/CHC POPS LINGERING OVER THE ERN ZNS WITH PERSISTENT CYC NW LLVL FLOW UNDER DEEPER MSTR. THERE WL BE MORE SUNSHINE OVER THE W...AND MIXING TO H85 ON NAM FCST SDNGS SUPPORTS HI TEMPS IN THE MID-UPR 50S RANGE OVER THE W AND SCNTRL. NAM FINALLY SHOWS CLOSED LO PULLING FAR ENUF TO THE E ON SAT NGT THAT MID LVL MSTR BEGINS TO DEPART THE ERN ZNS. LOOKS LIKE A CHILLY NGT SETTING UP OVER THE INTERIOR W WITH LGT WINDS UNDER SFC RDG AXIS. WL GO NEAR THE LO END OF MOS GUIDANCE IN THESE AREAS BUT NOT TOO CHILLY AS NAM SHOWS PWAT NO LOWER THAN ABOUT 0.45 INCH. PER NCEP GUIDANCE...HAVE TRENDED TOWARD A 00Z CNDN/12Z ECMWF SCENARIO FOR SUN INTO MON. THESE MODELS SHOW A NRN BRANCH SHRTWV MOVING INTO THE UPR GRT LKS ON SUN AND SUPPRESSING POTENT SHRTWV IN THE SRN BRANCH FOR THE MOST PART TO THE S. THIS SCENARIO WOULD ALSO BE MORE CONSISTENT WITH THE MORE BLOCKY UPR PATTERN THAT HAS DVLPD OVER ERN CANADA. TO MESH BETTER WITH SURROUNDING OFFICES...BUMPED POPS UP TO 20 ALG THE WI BORDER AND EVEN TO 30 IN SRN MNM COUNTY ON SUN NGT WHEN CNDN MODEL SHOWS SHRTWV INTERACTING WITH SOMEWHAT HIER MSTR OVER WI. MAINTAINED DRY FCST FARTHER N WHERE DRY AIR WL BE MORE RESILIENT. TENDED TO DCRS CLD COVER ON MON WITH HI PRES UNDER UPR RDGING IN SCNTRL CAN BLDG INTO THE UPR LKS PER CNDN MODEL AND MOST RECENT NCEP MANUAL GUIDANCE. COORDINATED WITH APX/GRB/DLH. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... MVFR CIGS HAVE BEEN RISING OVER THE LAST FEW HRS...ESPECIALLY AT KCMX WHERE CIGS HAVE RISEN A BIT TO OCCASIONALLY VFR. IN GENERAL... EXPANSIVE LOW-LEVEL MOISTURE THAT HAS PERSISTED OVER THE UPPER LAKES INTO ONTARIO IS STILL SHOWING SIGNS OF THINNING OUT PER SATELLITE IMAGERY. SO...THERE SHOULD CONTINUE TO BE SOME IMPROVEMENT IN CIGS WITH CONDITIONS GRADUALLY TRENDING TOWARD SCT CLOUD COVER TODAY... FIRST AT KCMX EARLY AFTN THEN AT KSAW BY LATE AFTN. CIGS MAY MAY LIFT TO PREVAILING VFR BEFORE CLOUDS BECOME SCT. IN THE MEANTIME... AIRMASS REMAINS COLD ENOUGH FOR LAKE EFFECT PROCESSES TO CONTRIBUTE TO CLOUD COVER AND SOME LIGHT PCPN AT TIMES...MAINLY AT KSAW UNDER NRLY FLOW. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT THE PRES GRADIENT TO TIGHTEN TODAY INTO SATURDAY OVER ERN LAKE SUPERIOR AS A MID LEVEL AND SURFACE LOW DROP SOUTH THROUGH ERN ONTARIO AND THE SFC RDG FROM HUDSON BAY TO THE UPPER MISSISSIPPI VALLEY REMAINS IN PLACE. SO...NW WINDS WILL BACK NW AND INCREASE TO 15 TO 25 KT TODAY AND TO 30 KT LATE TONIGHT AND SATURDAY OVER THE EAST HALF PUSHING WAVE HEIGHTS INTO THE 5 TO 8 FT RANGE. WINDS WILL DIMINISH SAT NIGHT INTO SUN AS HIGH PRES BUILDS INTO THE REGION. E TO NE WINDS WILL DEVELOP FROM MON INTO TUE AS LOW PRES OVER THE CENTRAL PLAINS GRADUALLY SLIDES TO THE ENE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...KC AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS GAYLORD MI
139 AM EDT FRI OCT 12 2007 .AVIATION...INSTABILITY SHOWERS WILL BE THE RULE THROUGH THE DAY FRIDAY...AUGMENTED BY DEEPER MOISTURE ROTATING INTO NORTHERN MI FRIDAY NIGHT. EXPECTING MAINLY VFR CONDITIONS OUTSIDE OF RAIN SHOWERS WHERE OCCASIONAL MVFR CEILINGS ANTICIPATED. JPB && .PREV DISCUSSION... /ISSUED 959 PM EDT THU OCT 11 2007/ (SECOND UPDATE)...NOT A LOT GOING ON IN THE LARGE SCALE SCHEME OF THINGS THIS EVENING...AS TWIN UPPER LOWS TO THE EAST CONTINUE THE PROCESS OF DUMBELLING AROUND ONE ANOTHER. WATER VAPOR IMAGERY DOES SHOW SOME DRYING/SUBSIDENCE ROTATING SOUTHWESTWARD TOWARD NORTHERN MI. 00Z APX SOUNDING INDICATED INVERSION HEIGHTS AROUND 800MB/-5C... 850MB TEMPERATURE NEAR -3C WITH COLDER TEMPERATURES TO THE NORTH PER AIRCRAFT SOUNDINGS (-4 TO -5C ACROSS THE UPPER PENINSULA). SCATTERED SHOWERS CONTINUE NEAR LAKE HURON...SOME SHOWERS HAVE ALSO BLOSSOMED QUICKLY AROUND GRAND TRAVERSE BAY...LOOKS LIKE ALONG NORTH-SOUTH CONVERGENCE AXIS EVIDENT IN RADAR IMAGERY BACKING ITS WAY WESTWARD INTO THE BAY. MORE RAIN SHOWERS OCCURRING OVER LAKE SUPERIOR...WITH MONTREAL RIVER RADAR INDICATING SOME OF THIS ACTIVITY BRUSHING FAR WESTERN CHIPPEWA COUNTY. ACROSS EASTERN UPPER...WINDS INITIALLY NORTH/NORTHEAST ACROSS EASTERN UPPER...KEEPING LOW LEVEL TRAJECTORIES PRIMARILY OUT OF ONTARIO (AND DOWNSLOPING TO BOOT). THIS WILL SLOWLY CHANGE OVERNIGHT AS WINDS BACK TO NORTH-NORTHWEST LATE. WILL CARRY SOME EARLY SHOWERS ACROSS FAR WESTERN CHIPPEWA COUNTY...THEN SPREAD THIS ACTIVITY A BIT FARTHER INLAND TOWARD MORNING AS WINDS SHIFT. AREAS ALONG-EAST OF I-75 WILL PROBABLY SEE PARTLY CLOUDY SKIES FOR THE MOST PART OVERNIGHT. ACROSS NORTHERN LOWER...INVERSION HEIGHTS FORECAST TO POKE ABOVE 800MB OVERNIGHT AS LOW/MID LEVEL COLD ADVECTION WINS OUT OVER GENERAL ONGOING SUBSIDENCE. SO SHOWER ACTIVITY EXPECTED TO CONTINUE PREDOMINANTLY IN AREAS FAVORED BY NORTHERLY FLOW... THOUGH MEAN LOW LEVEL FLOW EXPECTED TO BACK MORE NORTHWEST LATE. WILL MAKE SOME TWEAKS TO THE TEMPERATURE GRIDS AS WELL GIVEN VARYING AMOUNTS OF CLOUD COVER ACROSS THE AREA OVERNIGHT. JPB FIRST UPDATE... /ISSUED 800 PM EDT THU OCT 11 2007/ IN LIEU OF ISSUING AN AVIATION DISCUSSION THAT NO ONE IS GOING TO READ...WILL ISSUE AN EARLY UPDATE SINCE HAVE ALREADY MADE CHANGES TO THE GRIDS. SCATTERED SHOWERS HAVE BEEN DEVELOPING EAST OF I-75 THIS EVENING...AS OPPOSED TO WEST OF I-75 WHERE EARLIER SPOTTY PRECIPITATION HAS DISSIPATED. A LITTLE DRIER ALOFT OVER UPPER MI/NORTHWEST LOWER PER RECENT AIRCRAFT SOUNDINGS MAY BE A FACTOR IN THIS. THIS IS NOT LIKELY TO CHANGE OVERNIGHT...THOUGH IT IS GETTING COLDER ALOFT (EARLY PEEK AT INCOMING APX SOUNDING DATA INDICATES 850MB TEMPERATURES DOWN TO -2.5C). HAVE REMOVED SHOWER MENTION FOR NORTHWEST LOWER THIS EVENING...WILL KEEP IT IN OVERNIGHT FOR NOW GIVEN INCREASING OVER WATER INSTABILITY AND RE-EVALUATE THROUGH THE EVENING. HAVE ADDED SHOWERS TO NORTHEAST LOWER GIVEN CURRENT ACTIVITY. HAVE MESSED AROUND WITH CLOUD COVER A BIT AS WELL WITH BREAKS ACROSS PARTS OF EASTERN UPPER AND THE TIP OF THE MITT...COULD END UP BEING THAT AREAS AROUND THE ST. MARY`S RIVER STAY PARTLY CLOUDY OVERNIGHT. WILL BE ISSUING ANOTHER DISCUSSION AROUND 0215Z. NEW GRIDS ALREADY PUBLISHED. JPB DISCUSSION... /ISSUED 355 PM EDT THU OCT 11 2007/ WEAK SURFACE TROUGH REMAINS OVER THE WRN GREAT LAKES REGION LATE THIS AFTERNOON. DEPARTING UPPER LOW IS MOVING EAST THRU PENNSYLVANIA...WHILE ANOTHER UPPER LOW IS DROPPING SOUTH FROM JAMES BAY TOWARD LAKE HURON. SKIES REMAIN MOSTLY CLOUDY ACROSS OUR ENTIRE CWA. ERN UPR AND FAR NRN LWR MICHIGAN AWAY FROM PROMINENT LAKE INFLUENCES TRIED TO BREAK OUT OF THE CLOUDS...BUT TO NO AVAIL AS SELF-DESTRUCT SUNSHINE LEAD TO ONLY MORE CLOUD DEVELOPMENT WITH LIMITED LOW LEVEL MOISTURE TRAPPED BELOW THE INVERSION. LAKE EFFECT RAIN SHOWERS...ON THE OTHER HAND...HAVE TENDED TO DIMINISH OVER TIME THIS AFTERNOON AS REMAINING MOISTURE APPEARS TO BE TOO SHALLOW TO SUPPORT SIGNIFICANT PRECIP PRODUCTION DESPITE DELTA T`S IN THE MID TO UPPER TEENS. PRIMARY FORECAST QUESTION OVER THE NEXT 24 HOURS WILL BE POPS...AMOUNT AND COVERAGE...AS THE UPPER LOW TO THE NORTH PLUNGES SOUTH INTO SE ONTARIO. ADDITIONAL CONCERNS WILL BE TEMPS (SPECIFICALLY TEMP PROFILE) AND WINDS (SPEED AND DIRECTION) AS MORE COLD AIR ACCOMPANIES THIS UPPER LOW FEATURE. TONIGHT AND FRIDAY...JAMES BAY LOW WILL STEADILY DROP SOUTH ALONG THE ONTARIO/QUEBEC BORDER TONIGHT AND THEN INTO SE ONTARIO ON FRIDAY. A REINFORCING SHOT OF COLD AIR WILL ACCOMPANY THIS SYSTEM. 850 MB TEMPS DROP TO -3 C BY 12Z FRIDAY AND REMAIN UNCHANGED THROUGHOUT THE DAY. LOW LEVEL WINDS WILL GRADUALLY SHIFT FROM DUE NORTH THIS EVENING TO NORTHWEST BY MIDDAY FRIDAY. MAIN LIMITING FACTOR TO PRECIP PRODUCTION (SYNOPTIC OR LAKE EFFECT) WILL BE SHALLOW AND RATHER SPARSE LOW LEVEL MOISTURE. 900-700 MB RH WILL REMAIN AT AROUND 50-60 PCT THRU FRIDAY...ALTHOUGH A BIT HIGHER (NEAR 70 PCT) FOR NE SECTIONS OF OUR CWA CLOSER TO THE APPROACHING UPPER LOW. A LOOK AT UPSTREAM OBS DOES INDICATE LIGHT RAIN/SNOW SHOWERS OCCURRING ALONG THE SW SIDE OF THE UPPER LOW NORTH OF LAKE SUPERIOR AND SAULT STE MARIE AIDED BY A SHORT WAVE ROTATING AROUND THE UPPER LOW. HOWEVER...THESE AREAS ARE STILL NOT WITHIN THE AREA OF DEEP WRAP-AROUND MOISTURE ASSOCIATED WITH THE LOW CENTER. THIS MOISTURE WILL NOT REACH OUR CWA UNTIL FRIDAY NIGHT. THUS...ANY PRECIP OVER THE NEXT 24 HOURS WILL REMAIN LIGHT AND SPOTTY...WITH FOCUS OF CHANCE POPS SHIFTING FROM N FLOW LOCATIONS THIS EVENING (I.E. THE LEELANAU PENINSULA TO MANISTEE) TO N/NW FLOW LOCATIONS OVERNIGHT (I.E. WEST OF US-131) AND THEN TO NW FLOW AREAS ON FRIDAY (I.E. ALONG AND WEST OF US-131...PRESQUE ISLE TO THUNDER BAY...AND NRN SECTIONS OF CHIPPEWA COUNTY. MODELS SOUNDINGS SHOW ZERO ISOTHERM TRYING TO DROP BELOW 2500 FT...BUT JUST FALLING SHORT. THUS...EXPECT ALL PRECIP SHOULD REMAIN LIQUID. MOST OF OUR NEARSHORE AREAS WILL CONTINUE TO EXPERIENCE WIND GUSTS TO 25 KTS TONIGHT THRU FRIDAY (AT LEAST) AS SURFACE PRESSURE GRADIENT REMAINS TIGHT ON THE BACKSIDE OF THE APPROACHING UPPER LOW. WILL THEREFORE EXTEND SCA`S THRU 00Z SATURDAY. LONGER RANGE FORECAST (FRIDAY NIGHT THROUGH NEXT THURSDAY)...LOTS OF QUESTION MARKS DURING THIS PERIOD AS EXTENDED MODELS OFFER A VARIETY OF SOLUTIONS. IT DOES NOT APPEAR AS THOUGH IT WILL WARM UP THIS WEEKEND AS THE MODELS CONTINUE TO TREND ON THE COOLER SIDE. NEXT WEEK IS WHERE THE MAIN CONCERNS ARE AS MODELS VARY ON THE MOVEMENT/ STRENGTH OF A CUTOFF UPPER LOW PROGRESSING TO THE EAST OUT OF THE SOUTHERN STATES. THE INTERACTION OF THIS SYSTEM WITH AN OMEGA BLOCK HIGH WILL BE THE MAIN FOCUS OF THIS PORTION OF THE PACKAGE. FRIDAY NIGHT...MODELS BRING CUTOFF UPPER LOW CURRENTLY EVIDENT ON WATER VAPOR LOOP NEAR GEORGIAN BAY SOUTHWARD AND EVEN APPEAR TO RETROGRADE THIS FEATURE TO THE WEST JUST A TAD. MEANWHILE...OVER LAKE INSTABILITY CONTINUES WITH DELTA TS REMAINING IN THE MIDDLE TO UPPER TEENS. MOISTURE IS ON THE UPTICK WITH MEAN 900-700 MB RH INCREASING TO BETWEEN 90 AND 95 PERCENT NORTHEAST AND 60 TO 70 PERCENT FAR SOUTH. THEREFORE...CONTINUED CHANCE OF LAKE EFFECT RAIN SHOWERS ACROSS NORTHWEST FLOW AREAS AND ADDED A SLIGHT CHANCE OF SHOWERS ACROSS THE NORTHEAST DUE TO SOME LIMITED SYNOPTIC SUPPORT FROM THE UPPER LOW WHICH INCHES A LITTLE CLOSER. LOWS IN THE MIDDLE TO UPPER 30S. SATURDAY...MODEL SOUNDINGS/CROSS SECTIONS SHOW LOW LEVEL MOISTURE LINGERING IN THE MORNING (MEAN 900-700 MB RH STILL 85 TO 95 PERCENT) BUT SLOWLY DISSIPATING IN THE AFTERNOON (MEAN 900-700 MB RH FALLING TO NEAR 35 PERCENT FAR NORTHWEST AND 65 TO 75 PERCENT SOUTHEAST BY 00Z SUN). SO EXPECT MOSTLY CLOUDY SKIES IN THE MORNING TO PARTIALLY CLEAR FROM NORTHWEST TO SOUTHEAST IN THE AFTERNOON. HIGHS ONLY IN THE LOWER TO MIDDLE 50S. SATURDAY NIGHT...DRIER AIR CONTINUES TO OVERSPREAD THE FORECAST AREA WITH MEAN 900-700 MB RH FALLING TO BETWEEN 25 AND 35 PERCENT LEADING TO MOSTLY CLEAR TO PARTLY CLOUDY SKIES WITH LOWS IN THE LOWER TO MIDDLE 30S. SUNDAY...UPPER LEVEL RIDGING/HEIGHT RISES SHOULD LEAD TO THE DRY AIR HOLDING ON FOR MUCH OF THE DAY YIELDING PARTLY TO MOSTLY SUNNY SKIES. HIGHS A BIT MILDER WITH MIDDLE 50S TO NEAR 60 EXPECTED. MONDAY THROUGH THURSDAY...THIS TIME PERIOD IS WHERE THE MODELS ARE HAVING DIFFICULTY DECIPHERING THE DETAILS. THE CRUX OF THE PROBLEM LIES IN THE HANDLING OF AN UPPER LOW THAT MOVES OUT OF THE SOUTHWESTERN STATES AS THIS SYSTEM IS RUNNING INTO AN OMEGA BLOCK EXTENDING FROM THE EASTERN PLAINS INTO THE WESTERN GREAT LAKES. A MAJORITY OF THE EXTENDED MODELS DO WEAKEN THE UPPER LOW AS IT APPROACHES OUR FORECAST AREA. THE ECMWF IS THE MOST AGGRESSIVE IN THE WEAKENING WHICH APPEARS TO MAKE THE MOST SENSE WHILE THE GFS STILL BRINGS A DECENT AMOUNT OF MOISTURE SEEMINGLY THROUGH THE RIDGE. FOR NOW WILL CONTINUE WITH THE DRY FORECAST BUT CONFIDENCE IS ON THE LOWER SIDE. WILL TRIM BACK HIGHS BY A FEW DEGREES INTO THE SEASONABLE UPPER 50S TO LOWER 60S AS MORE CLOUD COVER IS EXPECTED AT A MINIMUM. SULLIVAN && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
930 AM PDT FRI OCT 12 2007 .SYNOPSIS... UPPER LEVEL LOW PRESSURE APPROACHING FROM THE NORTHWEST WILL BRING VARIABLE CLOUDINESS TODAY. CHANCE OF SHOWERS THIS EVENING THROUGH SATURDAY MORNING...ALONG WITH LOCAL STRONG GUSTY WEST WINDS IN THE MOUNTAINS AND DESERTS. FAIR AND WARMER SUNDAY UNDER HIGH PRESSURE. PARTLY CLOUDY AND COOLER EARLY NEXT WEEK THEN FAIR AND WARMER TOWARD THE END OF THE WEEK. && .DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO... ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES. .SHORT TERM (TODAY-MON)... LOW CLOUDS AND PATCHY FOG WERE INTO THE COASTAL MOUNTAIN SLOPES THIS MORNING. THERE WERE ALSO HIGH CLOUDS IN THE NRN AREAS. THE 12Z NKX SOUNDING HAD AN INVERSION BASED NEAR 3500 FT AND SHOWED THE HIGH LEVEL MOISTURE IN SW WINDS ALOFT. ONSHORE GRADIENTS AND TRENDS WITH ABOUT 7 MB SAN-IPL. THE DEEP MARINE LAYER WILL RESULT IN A PARTIAL AND REVERSE CLEARING PATTERN TODAY. THE UPPER LOW CURRENTLY CENTERED OFF THE NRN CA COAST WILL DIG SW ACROSS SRN CA TONIGHT. THIS WILL BRING A CHANCE OF SHOWERS...MAINLY OVER AND W OF THE MOUNTAINS. IF PRECIP DEVELOPS THEN RAINFALL TOTALS SHOULD GENERALLY BE LESS THAN A TENTH OF AN INCH...BUT THERE COULD BE LOCAL AMOUNTS TO NEAR A QUARTER INCH ON W FACING LOWER MOUNTAIN SLOPES. THE CHANCE OF SHOWERS WILL TAPER OFF SAT MORNING AND MOSTLY END BY AFTERNOON...EXCEPT FOR A FEW SHOWERS POSSIBLY LINGERING IN THE MOUNTAINS. INCREASING WINDS ALOFT AND ONSHORE GRADIENTS WILL CAUSE LOCAL GUSTY WINDS...MAINLY IN THE MOUNTAINS AND DESERTS THIS AFTERNOON THROUGH SAT AND WIND ADVISORIES ARE IN EFFECT. THERE COULD BE A RETURN OF MARINE LAYER CLOUDS SAT NIGHT AND SUN MORNING AND AGAIN SUN NIGHT INTO M0N SINCE THE LOW LEVELS REMAIN MOIST. OTHERWISE...FAIR AND WARMER WITH A SHORT WAVE RIDGE SUN...WEAKENING MON FOR A LITTLE COOLING. && .LONG TERM (TUE-FRI)... A FAST MOVING SHORT WAVE TROUGH WILL MOVE THROUGH MON NIGHT WITH BRIEF WEAK RIDGING TUE AND THEN ANOTHER BROADER TROUGH WILL MOVE THROUGH TUE NIGHT. THIS WILL MAINTAIN A MODERATELY DEEP MARINE LAYER WITH PARTLY CLOUDY SKIES IN MOST AREAS DURING THE AFTERNOONS AND BELOW SEASONAL TEMPS THROUGH WED. FAIR AND WARMER TOWARD THE END OF NEXT WEEK UNDER HIGH PRESSURE WITH WEAK OFFSHORE FLOW. && .AVIATION... 121430Z...MDCRS SOUNDINGS AND EARLY MORNING TOP REPORTS INDICATE THE MARINE LAYER HAD DEEPENED TO AROUND 4000 FEET. STRATOCU WITH BASES AROUND 3000 TO 3500 FEET MSL EXTENDS FROM THE COASTAL WATERS TO THE COASTAL SLOPES OF THE MOUNTAINS. DEPTH OF THE MARINE LAYER AND CONTINUED ONSHORE FLOW SHOULD KEEP A STRATOCU LAYER OVER THE AREA THROUGH THE AFTERNOON WITH SOME SCATTERING POSSIBLE ALONG THE COAST UNDER A REVERSE CLEARING PATTERN. HOWEVER...ANY CLEARING SHOULD BE BRIEF. CLOUDS SHOULD LOWER AND THICKEN THIS EVENING AND TONIGHT AS A COLD FRONT APPROACHES FROM THE NORTHWEST. THIS COLD FRONT IS EXPECTED TO MOVE THROUGH SOUTHERN CALIFORNIA BETWEEN 12Z AND 15Z ON SATURDAY. THIS FRONT SHOULD BRING SOME SHOWERS LATE TONIGHT INTO SATURDAY MORNING. CLOUDS SHOULD BREAK UP BEHIND THE FRONT ON SATURDAY. GUSTY SOUTHWEST TO WEST WINDS ACROSS THE MOUNTAINS SHOULD BRING SOME MOUNTAIN WAVE/ROTOR ACTIVITY TO THE ADJACENT DESERT AREAS ESPECIALLY NEAR KPSP TODAY AND TONIGHT. HORTON && .SGX WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FOR THE HIGHER MOUNTAINS AND FOR THE DESERTS FROM 2 PM THIS AFTERNOON UNTIL 8 PM SATURDAY. SEE LAXNPWSGX. && $$ PUBLIC...DVA AVIATION...HORTON
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS MARQUETTE MI
740 AM EDT FRI OCT 12 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF OVER ERN CANADA WITH PAIR OF CLOSED LO CENTERS JUST S OF JAMES BAY MOVING SSW AND THE OTHER OVER THE MID ATLANTIC STATES MOVG E TENDING TO SPIN ARND EACH OTHER WITHIN THE AREA OF LOWER HGTS. THERE IS A SHARP GRADIENT OF H85-7 MSTR ON THE WRN FLANK OF THIS TROF AND TO THE E OF RDG AXIS EXTENDING FM WRN HUDSON BAY INTO THE UPR MS RIVER VALLEY. ALTHOUGH THE UPR LO NEAR JAMES BAY APPEARS TO BE MOVING JUST A BIT W OF DUE S...WV IMAGERY INDICATES DEEPER MSTR ON ITS NW FLANK IS TENDING TO PUSH MORE TO THE W ACRS NCNTRL ONTARIO. EVEN THOUGH THE DEEPER MSTR IS CURRENTLY TO THE E...QUITE A BIT OF SC NOTED IN THE LLVL NLY FLOW BTWN SFC RDG AXIS OVER WRN LK SUP AND LO PRES TO THE E. 00Z TAMDAR SDNG SHOWS QUITE A BIT OF LLVL MSTR TRAPPED BLO SHARP INVRN ARND H85...MARKING THE SUBSIDENCE INVRN ABV LLVL THERMAL TROFFING. SCT LK EFFECT SHRA ARE MOST PERSISTENT OVER THE NCNTRL ZNS WHERE LLVL NLY FLOW IS UPSLOPING. EVEN THOUGH THE LOWEST TEMP AT THE INVRN BASE IS ONLY -6C...NOT TYPICALLY LO ENUF TO SUPPORT ICE NUCLEATION...SOME SN HAS MIXED IN WITH THE RA SINCE LAST EVNG OVER THE HIER TERRAIN. MORE BRKS IN THE CLD NOTED OVER THE SCNTRL WHERE LLVL FLOW IS DOWNSLOPING AND OVER THE W...CLOSER TO THE RDG AXIS AND DRIER LLVL AIR SHOWN ON THE 00Z YPL/INL RAOBS. ANOTHER SHRTWV OVER SCNTRL CAN IS LIFTING NEWD OVER RDG AXIS JUST TO THE W OF THE CWA AND BRINGING A BAND OF CLD/SHRA AS FAR E AS WRN MN. MAIN FCST CONCERNS THIS PACKAGE ARE CLD TRENDS/SHRA CHCS IN NNW FLOW THAT IS FCST TO PERSIST BTWN RDG TO THE W AND AREA OF LOWER HGTS TO THE E. ONE CHALLENGE WL BE DETERMINING WHETHER ANY DEEPER MSTR TO THE E ASSOCIATED WITH UPR LO JUST S OF JAMES BAY CAN ROTATE FAR ENUF TO THE W TO BRING ANY ENHANCEMENT TO THE LK EFFECT SHRA OVER LK SUP. BOTH THE GFS/NAM HAVE TRENDED STEADILY WWD WITH TRACK/POSITION OF UPR LO S OF JAMES BAY MOVING TO THE SSW. THE 00Z NAM SHOWS THE HIER H7 RH BACKING INTO THE E HALF OF LK SUP BY 00Z THIS EVNG BUT REMAINING JUST TO THE NE OF THE LAND CWA THRU THAT TIME. AT THE SAME TIME...MODEL SHOWS THE LLVL FLOW BACKING MORE NW THRU THE DAY AS A SFC HI CENTER BLDS INTO WI. THIS CHANGE IN FLOW SHOULD ALLOW MORE CLRG OVER THE NCNTRL ZNS AS FLOW OFF LK SUP BECOMES LESS FVRBL BUT MORE CLD OVER THE E. HOWEVER...ANY PCPN SHOULD TEND TO DIMINISH WITH DIURNAL HTG TENDING TO DISRUPT ANY LK EFFECT PCPN AND LOWERING LLVL RH WITH INFUSION OF DRIER AIR FM THE NW/INSOLATION. MIXING TO H85 OR SO ON NAM FCST SDNGS YIELDS HI TEMPS ARND 45 OVER THE HIER TERRAIN OF THE NW TO THE LO 50S OVER THE SCNTRL ARND MNM. TNGT...NAM IS MORE AGGRESSIVE AT BACKING MORE SUBSTANTIAL MSTR SWWD THAN THE GFS. CONSIDERING RECENT MODEL TRENDS IN HI AMPLITUDE BLOCKING PATTERN AS WELL AS WV IMAGERY SHOWING DEEPER MSTR BACKING FARTHER W...WL TEND TOWARD THE NAM FCST SCENARIO. NAM EVEN GENERATES SOME LGT PCPN OVER THE ERN ZNS WHERE LLVL CYC NW FLOW WL HAVE A LONGER FETCH ACRS THE ERN LK IN PRESENCE OF H85 THERMAL TROFFING. ADDED CHC POPS FOR THESE LK EFFECT SHRA OVER AREAS NR LK SUP E OF MUNISING AFT MIDNGT WHEN DEEPER MSTR ARRIVES. TENDED TOWARD THE HIER ETA MOS FOR THE ERN ZNS BUT TOWARD THE LOWER GFS MOS FOR THE INTERIOR W...WHERE SKIES ARE LIKELY TO REMAIN MOCLR IN PRESENCE OF PWAT BTWN 0.25 AND 0.50 INCH. TENDED TOWARD THE SLOWER NAM AGAIN ON SAT WITH MORE MSTR/CLDS/CHC POPS LINGERING OVER THE ERN ZNS WITH PERSISTENT CYC NW LLVL FLOW UNDER DEEPER MSTR. THERE WL BE MORE SUNSHINE OVER THE W...AND MIXING TO H85 ON NAM FCST SDNGS SUPPORTS HI TEMPS IN THE MID-UPR 50S RANGE OVER THE W AND SCNTRL. NAM FINALLY SHOWS CLOSED LO PULLING FAR ENUF TO THE E ON SAT NGT THAT MID LVL MSTR BEGINS TO DEPART THE ERN ZNS. LOOKS LIKE A CHILLY NGT SETTING UP OVER THE INTERIOR W WITH LGT WINDS UNDER SFC RDG AXIS. WL GO NEAR THE LO END OF MOS GUIDANCE IN THESE AREAS BUT NOT TOO CHILLY AS NAM SHOWS PWAT NO LOWER THAN ABOUT 0.45 INCH. PER NCEP GUIDANCE...HAVE TRENDED TOWARD A 00Z CNDN/12Z ECMWF SCENARIO FOR SUN INTO MON. THESE MODELS SHOW A NRN BRANCH SHRTWV MOVING INTO THE UPR GRT LKS ON SUN AND SUPPRESSING POTENT SHRTWV IN THE SRN BRANCH FOR THE MOST PART TO THE S. THIS SCENARIO WOULD ALSO BE MORE CONSISTENT WITH THE MORE BLOCKY UPR PATTERN THAT HAS DVLPD OVER ERN CANADA. TO MESH BETTER WITH SURROUNDING OFFICES...BUMPED POPS UP TO 20 ALG THE WI BORDER AND EVEN TO 30 IN SRN MNM COUNTY ON SUN NGT WHEN CNDN MODEL SHOWS SHRTWV INTERACTING WITH SOMEWHAT HIER MSTR OVER WI. MAINTAINED DRY FCST FARTHER N WHERE DRY AIR WL BE MORE RESILIENT. TENDED TO DCRS CLD COVER ON MON WITH HI PRES UNDER UPR RDGING IN SCNTRL CAN BLDG INTO THE UPR LKS PER CNDN MODEL AND MOST RECENT NCEP MANUAL GUIDANCE. COORDINATED WITH APX/GRB/DLH. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... VFR CIGS ARE EXPECTED AT KCMX WITH OCNL MVFR CIGS AT KSAW WITH PERSISTENT LAKE EFFECT CLOUDS AND A FEW LIGHT SHOWERS DOWNWIND FROM NRLY FLOW ACROSS LAKE SUPERIOR. CLOUD COVER IS EXPECTED TO THIN OUT TODAY WITH CONDITIONS TRENDING TOWARD SCT CLOUD COVER FIRST AT KCMX EARLY AFTN THEN AT KSAW BY LATE AFTN AS WINDS GRADUALLY BACK TO NW. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT THE PRES GRADIENT TO TIGHTEN TODAY INTO SATURDAY OVER ERN LAKE SUPERIOR AS A MID LEVEL AND SURFACE LOW DROP SOUTH THROUGH ERN ONTARIO AND THE SFC RDG FROM HUDSON BAY TO THE UPPER MISSISSIPPI VALLEY REMAINS IN PLACE. SO...NW WINDS WILL BACK NW AND INCREASE TO 15 TO 25 KT TODAY AND TO 30 KT LATE TONIGHT AND SATURDAY OVER THE EAST HALF PUSHING WAVE HEIGHTS INTO THE 5 TO 8 FT RANGE. WINDS WILL DIMINISH SAT NIGHT INTO SUN AS HIGH PRES BUILDS INTO THE REGION. E TO NE WINDS WILL DEVELOP FROM MON INTO TUE AS LOW PRES OVER THE CENTRAL PLAINS GRADUALLY SLIDES TO THE ENE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...KC AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1000 AM EDT FRI OCT 12 2007 .SYNOPSIS... LOW PRESSURE ALONG THE MID ATLANTIC COAST WILL MOVE NORTHEAST TO MAINE TODAY. A RIDGE OF HIGH PRESSURE OVER THE WESTERN GREAT LAKES WILL BUILD EAST ACROSS THE OHIO VALLEY OVER THE WEEKEND. LOW PRESSURE WILL RAPIDLY APPROACH FROM THE WEST ON MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... TAMDAR DATA INDICATING LOW LEVEL MOISTURE STILL HANGING ON...DRIER AIR WILL TRY TO WORK INTO WESTERN AREAS THIS AFTERNOON AND SO WENT BECOMING PARTLY SUNNY. EASTERN AREAS MAY SEE SOME BREAKS SO WENT WITH MOSTLY CLOUDY WITH SOME SHOWERS. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... NEUTRAL TEMP ADVECTION WILL CONTINUE TONIGHT WITH 850 MB TEMPS AROUND 0 DEG. W TO NW FLOW EXPECTED TONIGHT SO WILL MAINTAIN SMALL CHANCE POPS FOR NE OH AND NW PA INTO SAT. REALISTICALLY...BEST CHANCES FOR ADDITIONAL PRECIP WILL BE BEFORE MID AS 850 MB FLOW ACTUALLY TRIES TO BECOME ANTICYCLONIC SATURDAY MORNING. 850 MB TEMPS SHOULD MANAGE A GOOD 2 TO 3 DEG RISE BY 00Z SUN SO IT SHOULD BE A LITTLE WARMER ON SAT THAN TODAY. MORE SUN ALSO EXPECTED. CANNOT RULE OUT A FEW SPRINKLES OR LIGHT SHRA IN NW PA BUT PRECIP AMOUNTS WILL BE MINIMAL. THE NEXT COUPLE OF NIGHTS WILL BE CHILLY AND MAY HAVE TO WORRY ABOUT SOME FROST LATER TONIGHT IF WINDS DIE DOWN. WILL LET DAY CREW TAKE A GOOD LOOK AT THAT. WILL UNDERCUT GUID TEMPS FOR SUN AM AS WELL AND MOS FORECASTS IN THE LOWER 40S SEEM A TAD WARM GIVEN AIRMASS. && .LONG TERM /SUNDAY THROUGH THURSDAY/... MODELS CONTINUE TO DEVELOP SPLIT FLOW ALOFT ACROSS THE CONUS...BUT DIFFER SIGNIFICANTLY ON EXACT LOCATION AND MOVEMENT OF SFC FEATURES. GFS AND DGEX DIFFER FROM YDY...BUT ARE IN CLOSE AGREEMENT. BOTH MOVE A LOW PRESSURE SYSTEM ACROSS NORTHERN ILLINOIS TUESDAY...AND THEN WEAKENS AS IT MOVES ACROSS OHIO ON WEDNESDAY. HPC PREFERS ECMWF SOLUTION WHICH IS SIMILAR TO THE GFS ENSEMBLE SOLUTION. LARGE AREA OF HIGH PRESSURE REMAINS INTACT ACROSS GREAT LAKES. SFC LOW FROM MISSOURI ON TUESDAY...ACROSS LOWER MISSISSIPPI VALLEY AS A TROUGH ON WEDNESDAY. DO PUT IN CHC POPS ON WEDNESDAY. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... LAKE EFFECT RAIN SHOWERS WILL CONTINUE AS A BAND SET UP THIS MORNING FROM LAKE HURON ACROSS LAKE ERIE INTO NORTHEAST OHIO. WILL CONTINUE TO MENTION SHOWERS ACROSS NORTHEAST OHIO THROUGH THE MORNING HOURS. FLOW IS EXPECTED TO SHIFT TO A MORE WESTERLY DIRECTION AND SHIFT THE SHOWER ACTIVITY UP TO ERIE THIS AFTERNOON. TOLEDO AND FINDLAY SHOULD REMAIN DRY THROUGH THE PERIOD. STILL SOME OCCASIONAL MVFR CEILINGS TO DEAL WITH BUT IT WILL ALTERNATE BETWEEN MVFR AND VFR THROUGH THE AFTERNOON. SHOULD GO VFR ALL AREAS AFTER 00Z THIS EVENING. OUTLOOK... INSTABILITY CLOUDS WILL CONTINUE INTO EARLY IN THE WEEKEND WITH THE SHOWERS MAINLY CLOSE TO LAKE ERIE. FOR THE MOST PART VFR EXCEPT MVFR IN SHOWERS. SUNDAY THROUGH MONDAY SHOULD BE VFR AS A SOUTHWEST FLOW RETURNS. && .MARINE... SURFACE LOW PULLING OUT WELL TO THE EAST OF THE AREA WILL ALLOW WINDS TO SUBSIDE DURING THE DAY TODAY. CYCLONIC FLOW WILL CONTINUE WITH NORTHWEST FLOW THROUGH THE DAY. WINDS SHOULD BE STRONG ENOUGH TO PRODUCE SMALL CRAFT ADVISORY WAVES ON THE LAKE SO WILL CONTINUE THE ADVISORY TODAY. AS HIGH PRESSURE BUILDS SOUTH OF THE AREA...LOW PRESSURE WILL SLIDE SOUTH TOWARD THE LAKE FROM CENTRAL QUEBEC. THE COMBINATION OF THE TWO WEATHER FEATURES WILL TIGHTEN UP THE GRADIENT ACROSS THE LAKE ONCE AGAIN ON SATURDAY. WINDS WILL ONCE AGAIN DIMINISH AS THE HIGH PRESSURE CENTER TRIES TO BUILD BACK NORTH ACROSS THE LAKE SATURDAY NIGHT INTO SUNDAY. WARM FRONT LIFTS NORTH OF THE LAKE SUNDAY NIGHT AND SOUTH TO SOUTHWEST FLOW DEVELOPS AND INCREASES INTO TUESDAY WITH CYCLONIC FLOW IN ADVANCE OF DEEP LOW MOVING NORTHEAST INTO THE CENTRAL GREAT LAKES. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LEZ142>149. && $$ SYNOPSIS...THOMPSON NEAR TERM...THOMPSON SHORT TERM...KUBINA LONG TERM...DJB AVIATION...LOMBARDY MARINE...LOMBARDY
AREA FORECAST DISCUSSION...UPDATED
NWS MORRISTOWN TN
1019 AM EDT FRI OCT 12 2007 .DISCUSSION... ACARS SOUNDINGS AND AREA RAOBS SHOW A VERY STRONG INVERSION FROM AROUND 800 MB UP TO ABOUT 720 MB. PLENTY OF MOISTURE IS TRAPPED BELOW THIS INVERION WITH ADDITIONAL UPSTREAM MOISTURE MOVING IN FROM THE NORTHWEST. WITH SURFACE HEATING IN THE CENTRAL AND SOUTHERN VALLEY...EXPECT SOME EROSION OF THE CLOUDS NEAR THE EDGES...BUT CLOUDS WILL BE BROKEN TO OVERCAST THROUGH MOST OF THE DAY IN THE NORTHERN SECTIONS AND THE MOUNTAINS. THE CURRENT FORECAST CAPTURES THESE TRENDS FAIRLY WELL...AND TEMPERATURES ARE ON TRACK...SO NO UPDATE WILL BE NEEDED. && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DGS
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
230 PM PDT FRI OCT 12 2007 .SYNOPSIS... UPPER LEVEL LOW PRESSURE APPROACHING FROM THE NORTHWEST WILL BRING A CHANCE OF SHOWERS THIS EVENING THROUGH SATURDAY MORNING...ALONG WITH LOCAL STRONG GUSTY WEST WINDS IN THE MOUNTAINS AND DESERTS. FAIR AND WARMER SUNDAY UNDER HIGH PRESSURE. PARTLY CLOUDY AND COOLER EARLY NEXT WEEK THEN FAIR AND WARMER TOWARD THE END OF THE WEEK. && .DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO... ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES. .SHORT TERM (TODAY-MON)... LOW CLOUDS AND PATCHY FOG WERE INTO THE COASTAL MOUNTAIN SLOPES THIS MORNING. SC BROKE UP IN A REVERSE CLEARING PATTERN BY NOON. EARLY AFTERNOON ACARS SOUNDINGS INDICATED AN INVERSION BASED NEAR 3800 FT WITH STRONG WSW WINDS ALOFT. ONSHORE GRADIENTS AND TRENDS WITH 7-8 MB SAN-IPL. THE UPPER LOW CURRENTLY CENTERED OFF THE CENTRAL CA COAST WILL DIG SW ACROSS SRN CA TONIGHT. THIS WILL BRING A CHANCE OF SHOWERS...MAINLY OVER AND W OF THE MOUNTAINS. IF PRECIP DEVELOPS THEN RAINFALL TOTALS SHOULD GENERALLY BE LESS THAN A TENTH OF AN INCH...BUT THERE COULD BE LOCAL AMOUNTS TO NEAR A QUARTER INCH ON W FACING LOWER MOUNTAIN SLOPES. THE CHANCE OF SHOWERS WILL TAPER OFF SAT MORNING AND MOSTLY END BY AFTERNOON...EXCEPT FOR A FEW SHOWERS POSSIBLY LINGERING IN THE MOUNTAINS. INCREASING WINDS ALOFT AND ONSHORE GRADIENTS WILL CAUSE LOCAL GUSTY WINDS...MAINLY IN THE MOUNTAINS AND DESERTS THIS AFTERNOON THROUGH SAT AND WIND ADVISORIES ARE IN EFFECT. THERE COULD BE A RETURN OF MARINE LAYER CLOUDS SAT NIGHT AND SUN MORNING AND AGAIN SUN NIGHT INTO M0N SINCE THE LOW LEVELS REMAIN MOIST. OTHERWISE...FAIR AND WARMER WITH A SHORT WAVE RIDGE SUN...WEAKENING MON FOR A LITTLE COOLING. && .LONG TERM (TUE-FRI)... A FAST MOVING SHORT WAVE TROUGH WILL MOVE THROUGH MON NIGHT WITH BRIEF WEAK RIDGING TUE AND THEN ANOTHER BROADER TROUGH WILL MOVE THROUGH TUE NIGHT. THIS WILL MAINTAIN A MODERATELY DEEP MARINE LAYER WITH PARTLY CLOUDY SKIES IN MOST AREAS DURING THE AFTERNOONS AND BELOW SEASONAL TEMPS THROUGH WED. FAIR AND WARMER TOWARD THE END OF NEXT WEEK UNDER HIGH PRESSURE WITH WEAK OFFSHORE FLOW. && .AVIATION... 121930Z...MARINE LAYER DEPTH REMAINS AROUND 4000 FEET BUT SHOULD DEEPEN TO AROUND 6000 FEET TONIGHT. BROKEN STRATOCU WITH BASES AROUND 3500 FEET MSL EXTENDS FROM THE COAST WATERS TO THE COASTAL SLOPES OF THE MOUNTAINS. CLOUDS SHOULD LOWER TO AROUND 1500 TO 2000 FEET MSL THIS EVENING AND TONIGHT AS A COLD FRONT APPROACHES FROM THE NORTHWEST. THIS COLD FRONT WILL WEAKEN AS IT MOVES THROUGH SOUTHERN CALIFORNIA BETWEEN 12Z AND 16Z ON SATURDAY. THIS FRONT SHOULD BRING SCATTERED SHOWERS LATE TONIGHT INTO SATURDAY MORNING. CLOUDS SHOULD BECOME SCATTERED TO BROKEN DURING THE AFTERNOON ON SATURDAY. GUSTY SOUTHWEST TO WEST WINDS ACROSS THE MOUNTAINS SHOULD BRING SOME MOUNTAIN WAVE/ROTOR ACTIVITY TO THE ADJACENT DESERT AREAS ESPECIALLY NEAR KPSP THROUGH TONIGHT. HORTON && .SGX WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FOR THE HIGHER MOUNTAINS AND FOR THE DESERTS UNTIL 8 PM SATURDAY. SEE LAXNPWSGX. && $$ PUBLIC...DVA AVIATION...HORTON
AREA FORECAST DISCUSSION...CORRECTED TIME
NWS NORTHERN INDIANA
420 PM EDT FRI OCT 12 2007 .SHORT TERM... TONIGHT AND SATURDAY...THE MAIN CONCERNS ARE HOW COLD TEMPERATURES WILL BE TONIGHT AND HOW MUCH FROST WILL OCCUR. TEMPERATURES WERE STARTING OUT VERY CHILLY...WITH ONLY 48F AT HILLSDALE. MOST OTHER LOCATIONS WERE IN THE LOWER TO MID 50S. THE BASE OF A LARGE SUBSIDENCE INVERSION HAS BEEN LOWERING TODAY OVER THE REGION..HOWEVER...MOISTURE WAS INCREASING UPSTREAM. ACARS SOUNDINGS INDICATED PLENTY OF MOISTURE UPSTREAM FROM CENTRAL WI BACK INTO MN. BELIEVE CLOUD COVER OVER THE FORECAST AREA FRIDAY AFTERNOON IS MORE DIURNAL IN NATURE...BUT UPSTREAM CLOUDS ARE MORE SYNOPTICALLY DRIVEN. SKIES SHOULD TRY TO CLEAR THIS EVENING...BUT MORE CLOUDS SHOULD ATTEMPT TO MOVE IN LATER. FOR THIS PACKAGE...LOWERED TEMPS 1 TO 3 DEGREES AND EXPANDED THE CHANCE FOR FROST ACROSS THE ENTIRE AREA EXPECT FOR AREAS IMMEDIATELY DOWNSTREAM OF LAKE MICHIGAN. MAV MOS TEMPS PROBABLY A LITTLE TOO COLD PER COLD BIAS. && .LONG TERM... DRY AND WARMER CONDITIONS ARE EXPECTED SATURDAY NIGHT INTO SUNDAY AS SHRTWV RIDGE WILL SWING INTO THE OH VALLEY AND GREAT LAKES. INCREASED THE CLOUD COVER FOR LATE SATURDAY NIGHT AND SUNDAY MORNING DUE TO THETA-E ADVECTION AND A WEAK WARM FRONT THAT WILL PUSH INTO THE SRN LAKES. BOTH THE GFS AND NAM DO PRINT OFF SOME LIGHT QPF ACROSS THE FAR WESTERN CWA DURING THIS TIME. BEST DYNAMICS/ISENTROPIC LIFT WILL BE WELL WEST OF THE CWA...SO WILL NOT INTRODUCE ANY POPS/WX SUNDAY MORNING. DRY CONDITIONS AND ABOVE NORMAL TEMPS WILL PREVAIL SUNDAY NIGHT INTO MONDAY AS LLV WINDS WILL VEER MORE SOUTHERLY IN RESPONSE TO AN UPPER LEVEL LOW THAT WILL EJECT INTO THE IA AREA...ALLOWING THE WARM FRONT TO STALL OUT ACROSS SRN MI. THE MAIN FCST ISSUE IS THE EVOLUTION OF THIS UPPER LEVEL LOW MONDAY AFTERNOON THROUGH WEDNESDAY. THE 00Z ECMWF AND 00Z GFS PHASE THIS ENERGY WITH THE NRN STREAM ENERGY THAT WILL BE DIGGING INTO SOUTHWEST ONTARIO...THUS CLOSING OFF AN INTENSE CLOSED UPPER LOW THAT TRACKS SLOWLY EAST THROUGH THE UPPER MIDWEST AND NRN GREAT LAKES. THE 00/12Z GEM...GFS ENSEMBLE MEAN...AND 12Z GFS KEEP THESE WAVES SEPARATE...TRACKING A WEAKER SYSTEM THRU THE SRN GREAT LAKES AND NRN OH VALLEY. REGARDLESS...WILL MAINTAIN 30/40 POPS MONDAY NIGHT AND TUESDAY WITH SOME RESEMBLANCE OF A SFC REFLECTION AND UPPER TROUGH IN THE VICINITY. NOT ANY CAA OR DRY PUSH BEHIND THIS SYSTEM TO CLEAR OUT LLV MOISTURE...SO EXPECT PLENTY OF LINGERING LOW CLOUDS TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...ESPECIALLY WITH PROBABLE SUBSIDENCE INVERSION TRAPPING LLV MOISTURE IN. ONLY LOWERED TUE AND WED MAXES A FEW DEGREES...BUT WILL PROBABLY NEED TO LOWER FURTHER AS CONFIDENCE INCREASES. THERE IS A WIDE RANGE OF MODEL SOLUTIONS FOR DAY 6 AND 7 AS IT WILL ONCE AGAIN COME DOWN TO THE POTENTIAL PHASING OF THE NEXT WESTERN TROUGH AS IT EJECTS INTO THE CENTRAL/NORTHERN PLAINS. WILL SIDE WITH THE SLOWER ECMWF AND CLIMO...AND KEEP DAY 6/7 DRY AT THIS TIME. && .AVIATION/UPDATE... LAKE EFFECT SHOWERS HAVE DIMINISHED AHEAD OF A WEAK UPPER LEVEL SYSTEM THAT WAS OVER THE UPPER MIDWEST. HAVE ADDED SCATTERED SHOWERS OVER NORTHEAST AREAS AS THIS WEAK SYSTEM MOVES OVER FAR SOUTHERN LOWER MICHIGAN TOWARD NW OHIO. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM/AVIATION...SKIPPER LONG TERM...STEINWEDEL/FISHER
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
420 AM EDT FRI OCT 12 2007 .SHORT TERM... TONIGHT AND SATURDAY...THE MAIN CONCERNS ARE HOW COLD TEMPERATURES WILL BE TONIGHT AND HOW MUCH FROST WILL OCCUR. TEMPERATURES WERE STARTING OUT VERY CHILLY...WITH ONLY 48F AT HILLSDALE. MOST OTHER LOCATIONS WERE IN THE LOWER TO MID 50S. THE BASE OF A LARGE SUBSIDENCE INVERSION HAS BEEN LOWERING TODAY OVER THE REGION..HOWEVER...MOISTURE WAS INCREASING UPSTREAM. ACARS SOUNDINGS INDICATED PLENTY OF MOISTURE UPSTREAM FROM CENTRAL WI BACK INTO MN. BELIEVE CLOUD COVER OVER THE FORECAST AREA FRIDAY AFTERNOON IS MORE DIURNAL IN NATURE...BUT UPSTREAM CLOUDS ARE MORE SYNOPTICALLY DRIVEN. SKIES SHOULD TRY TO CLEAR THIS EVENING...BUT MORE CLOUDS SHOULD ATTEMPT TO MOVE IN LATER. FOR THIS PACKAGE...LOWERED TEMPS 1 TO 3 DEGREES AND EXPANDED THE CHANCE FOR FROST ACROSS THE ENTIRE AREA EXPECT FOR AREAS IMMEDIATELY DOWNSTREAM OF LAKE MICHIGAN. MAV MOS TEMPS PROBABLY A LITTLE TOO COLD PER COLD BIAS. && .LONG TERM... DRY AND WARMER CONDITIONS ARE EXPECTED SATURDAY NIGHT INTO SUNDAY AS SHRTWV RIDGE WILL SWING INTO THE OH VALLEY AND GREAT LAKES. INCREASED THE CLOUD COVER FOR LATE SATURDAY NIGHT AND SUNDAY MORNING DUE TO THETA-E ADVECTION AND A WEAK WARM FRONT THAT WILL PUSH INTO THE SRN LAKES. BOTH THE GFS AND NAM DO PRINT OFF SOME LIGHT QPF ACROSS THE FAR WESTERN CWA DURING THIS TIME. BEST DYNAMICS/ISENTROPIC LIFT WILL BE WELL WEST OF THE CWA...SO WILL NOT INTRODUCE ANY POPS/WX SUNDAY MORNING. DRY CONDITIONS AND ABOVE NORMAL TEMPS WILL PREVAIL SUNDAY NIGHT INTO MONDAY AS LLV WINDS WILL VEER MORE SOUTHERLY IN RESPONSE TO AN UPPER LEVEL LOW THAT WILL EJECT INTO THE IA AREA...ALLOWING THE WARM FRONT TO STALL OUT ACROSS SRN MI. THE MAIN FCST ISSUE IS THE EVOLUTION OF THIS UPPER LEVEL LOW MONDAY AFTERNOON THROUGH WEDNESDAY. THE 00Z ECMWF AND 00Z GFS PHASE THIS ENERGY WITH THE NRN STREAM ENERGY THAT WILL BE DIGGING INTO SOUTHWEST ONTARIO...THUS CLOSING OFF AN INTENSE CLOSED UPPER LOW THAT TRACKS SLOWLY EAST THROUGH THE UPPER MIDWEST AND NRN GREAT LAKES. THE 00/12Z GEM...GFS ENSEMBLE MEAN...AND 12Z GFS KEEP THESE WAVES SEPARATE...TRACKING A WEAKER SYSTEM THRU THE SRN GREAT LAKES AND NRN OH VALLEY. REGARDLESS...WILL MAINTAIN 30/40 POPS MONDAY NIGHT AND TUESDAY WITH SOME RESEMBLANCE OF A SFC REFLECTION AND UPPER TROUGH IN THE VICINITY. NOT ANY CAA OR DRY PUSH BEHIND THIS SYSTEM TO CLEAR OUT LLV MOISTURE...SO EXPECT PLENTY OF LINGERING LOW CLOUDS TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...ESPECIALLY WITH PROBABLE SUBSIDENCE INVERSION TRAPPING LLV MOISTURE IN. ONLY LOWERED TUE AND WED MAXES A FEW DEGREES...BUT WILL PROBABLY NEED TO LOWER FURTHER AS CONFIDENCE INCREASES. THERE IS A WIDE RANGE OF MODEL SOLUTIONS FOR DAY 6 AND 7 AS IT WILL ONCE AGAIN COME DOWN TO THE POTENTIAL PHASING OF THE NEXT WESTERN TROUGH AS IT EJECTS INTO THE CENTRAL/NORTHERN PLAINS. WILL SIDE WITH THE SLOWER ECMWF AND CLIMO...AND KEEP DAY 6/7 DRY AT THIS TIME. && .AVIATION/UPDATE... LAKE EFFECT SHOWERS HAVE DIMINISHED AHEAD OF A WEAK UPPER LEVEL SYSTEM THAT WAS OVER THE UPPER MIDWEST. HAVE ADDED SCATTERED SHOWERS OVER NORTHEAST AREAS AS THIS WEAK SYSTEM MOVES OVER FAR SOUTHERN LOWER MICHIGAN TOWARD NW OHIO. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM/AVIATION...SKIPPER LONG TERM...STEINWEDEL/FISHER
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
359 PM EDT FRI OCT 12 2007 .SHORT TERM...UP TO 00Z SUN UPPER AIR PATTERN CONSISTS OF A CLOSED 500 MB LOW EAST OF LAKE SUPERIOR ON THE QUE/ONT BORDER AND ANOTHER IN NEW ENGLAND. THE 500 MB LOW EAST OF LAKE SUPERIOR WILL RETROGRADE A BIT WESTWARD TONIGHT AND THEN HEAD EAST ON SUN AS BOTH LOWS KIND OF DUMBBELL AROUND EACH OTHER. FOR TONIGHT...DIURNAL SHOWERS WITH A BIT OF LAKE ENHANCEMENT SHOULD COME TO AN END THIS EVENING WITH THE LOSS OF HEATING WHICH HAS BEEN AIDING THE SHOWERS THIS AFTERNOON. THE SHOWERS ORIGINALLY LOOKED LIKE PURE LAKE EFFECT AS TAMDAR SOUNDINGS FROM KSAW WERE SHOWING 850 MB TEMPERATURES OF -6C AND GFS INITIALIZED BEST WITH THIS AT 12Z. NAM WAS WAY TOO WARM. ANYWAY...-6C IS ENOUGH FOR LAKE EFFECT WITH LAKE SUPERIOR TEMPERATURES BEING AROUND 8C TO 10C. GFS GFS HAS THE 850 MB TEMPERATURES WARM TO -2C BY 00Z. THIS GETS BORDERLINE FOR LAKE EFFECT...BUT WITH THE UPPER LOW GETTING CLOSER...WRAPAROUND MOISTURE WILL TRY TO HEAD BACK IN ESPECIALLY ACROSS THE EASTERN CWA. GFS IS SHOWING SOME WEAK 850-500 MB Q-VECTOR CONVERGENCE AS WELL...SO CHANCE POPS AFTER MIDNIGHT WITH SOME LAKE ENHANCEMENT THROWN IN LOOKS GOOD. LOOKS TOO WARM FOR SNOW...SO WILL KEEP PCPN AS RAIN AND KEEP IT CONFINED FROM KP59 EASTWARD. FOR SAT...AS THE LOW STARTS TO PULL BACK TO THE EAST...850 MB TEMPERATURES WARM AND THE WRAPAROUND MOVES BACK OUT...SO SHOWERS SHOULD COME TO AN END IN THE AFTERNOON EAST OF MUNISING. OVERALL...FOR TEMPERATURES...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST...JUST A FEW TWEAKS HERE AND THERE. .LONG TERM (SAT NIGHT THROUGH NEXT FRI)... FOLLOWED NCEP PREFERRED GFS/UMKET SOLUTIONS FOR EARLY TO MIDWEEK WHICH INDICATES MORE OF A SPLIT FLOW OVER THE UPR GREAT LAKES. THIS SOLUTION WAS FAVORED OVER THE NAM/CANADIAN MODELS WHICH SHOWS PHASING OF THE WRN CONUS MID/UPR TROF WITH A NRN BRANCH SHORTWAVE... FORMING A DEEPER CLOSED LOW OVER THE CENTRAL PLAINS. .SAT NIGHT INTO SUN...MODELS INDICATE NORTHERN PLAINS RIDGE WILL BECOME CENTERED OVER THE UPPER GREAT LAKES AS THE CLOSED LOW OVER NRN ONTARIO PULLS WELL E OF THE AREA. ASSOCIATED SUBSIDENCE WITH RIDGE AND LOSS OF CYCLONIC FLOW SHOULD ALLOW LAKE CLOUDS TO ERODE OVER ERN COUNTIES SAT NIGHT. PRECIP WATER MIN AXIS OF .25 INCH OVER THE WRN HALF OF THE CWA ALONG WITH CLEAR SKIES WILL ALLOW MIN TEMPS TO RADIATE DOWN TO THE UPR 20S OVER THE WRN INTERIOR...PER GFS MOS GUIDANCE. TEMPS WILL REBOUND UNDER NEARLY FULL SUNSHINE ON SUNDAY. WITH 850 MB TEMPS FCST AROUND 2C...EXPECT HIGHS IN THE MID-UPR 50S SOUTH BUT LIGHT NRLY ONSHORE FLOW WILL KEEP READINGS IN THE LOW-MID 50S NORTH. SUN NIGHT...EXPECT NRN BRANCH SHRTWV MOVING INTO THE UPR GRT LKS TO GENERALLY SUPPRESS ENERGY FROM SRN BRANCH/CENTRAL PLAINS SHORTWAVE TO THE SOUTH....IN LINE WITH GFS/UMKET SOLNS. THERE IS SOME WEAK WAA/INCREASED MOISTURE FROM SHORTWAVE RIPPLING THROUGH MID-UPR RDG WHICH MAY STILL BRING SOME ISOLD TO SCNTRL PORTIONS SUN NIGHT. SO WILL KEEP GOING SLIGHT CHC TO LOW CHC POPS OVER THESE COUNTIES WITH A DRY FCST ELSEWHERE UNDER INFLUENCE OF ONTARIO SFC HIGH. FOLLOWING SPLIT FLOW IDEA OF 12Z UKMET AND ECMWF KEPT FCST DRY MON THROUGH WED. ALTHOUGH WITH PREVAILING SFC FLOW EXPECTED TO BE NORTHEAST...DO NOT EXPECT ANY BIG WARMUP IN TEMPS. FOLLOWED PRETTY CLOSE TO GFS MOS GUIDANCE...WITH HIGHS GENERALLY IN THE 50S. KEPT N LOW CHC POPS FOR RAIN LATE NEXT WEEK (THU-FRI) AS THE GFS AND TO A LESSER EXTENT THE ECMWF ADVERTISE ANOTHER SHORTWAVE MOVING UP FROM THE PLAINS IN SW FLOW. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... CIGS WILL CONTINUE MVFR/VFR AT KCMX AND KSAW WHILE LONGER INTO THIS EVENING WITH LAKE EFFECT CLOUDS CONTINUING TO AFFECT THE SITE THROUGH THEN UNTIL THE WIND TURNS WEST AND STARTS BRINGING A BIT OF DRIER AIR IN. WITH DIURNAL HEATING AGAIN SAT MORNING...VFR/MVFR DECK WILL REFORM AGAIN WITH SOME LAKE CONTRIBUTION TO HELP FORM THE CLOUDS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... WITH HIGH PRESSURE REMAINING CLOSE BY THROUGH THE FORECAST PERIOD...DO NOT EXPECT GALES ANYTIME SOON AS THE PRESSURE GRADIENT IS NOT ALL THAT TIGHT. HIGHEST WINDS WILL BE TONIGHT AT 10 TO 20 KT AND NOTHING HIGHER IS FORESEEN ANYTIME SOON. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...MICHELS LONG TERM...VOSS AVIATION/MARINE...MICHELS
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS MARQUETTE MI
120 PM EDT FRI OCT 12 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF OVER ERN CANADA WITH PAIR OF CLOSED LO CENTERS JUST S OF JAMES BAY MOVING SSW AND THE OTHER OVER THE MID ATLANTIC STATES MOVG E TENDING TO SPIN ARND EACH OTHER WITHIN THE AREA OF LOWER HGTS. THERE IS A SHARP GRADIENT OF H85-7 MSTR ON THE WRN FLANK OF THIS TROF AND TO THE E OF RDG AXIS EXTENDING FM WRN HUDSON BAY INTO THE UPR MS RIVER VALLEY. ALTHOUGH THE UPR LO NEAR JAMES BAY APPEARS TO BE MOVING JUST A BIT W OF DUE S...WV IMAGERY INDICATES DEEPER MSTR ON ITS NW FLANK IS TENDING TO PUSH MORE TO THE W ACRS NCNTRL ONTARIO. EVEN THOUGH THE DEEPER MSTR IS CURRENTLY TO THE E...QUITE A BIT OF SC NOTED IN THE LLVL NLY FLOW BTWN SFC RDG AXIS OVER WRN LK SUP AND LO PRES TO THE E. 00Z TAMDAR SDNG SHOWS QUITE A BIT OF LLVL MSTR TRAPPED BLO SHARP INVRN ARND H85...MARKING THE SUBSIDENCE INVRN ABV LLVL THERMAL TROFFING. SCT LK EFFECT SHRA ARE MOST PERSISTENT OVER THE NCNTRL ZNS WHERE LLVL NLY FLOW IS UPSLOPING. EVEN THOUGH THE LOWEST TEMP AT THE INVRN BASE IS ONLY -6C...NOT TYPICALLY LO ENUF TO SUPPORT ICE NUCLEATION...SOME SN HAS MIXED IN WITH THE RA SINCE LAST EVNG OVER THE HIER TERRAIN. MORE BRKS IN THE CLD NOTED OVER THE SCNTRL WHERE LLVL FLOW IS DOWNSLOPING AND OVER THE W...CLOSER TO THE RDG AXIS AND DRIER LLVL AIR SHOWN ON THE 00Z YPL/INL RAOBS. ANOTHER SHRTWV OVER SCNTRL CAN IS LIFTING NEWD OVER RDG AXIS JUST TO THE W OF THE CWA AND BRINGING A BAND OF CLD/SHRA AS FAR E AS WRN MN. MAIN FCST CONCERNS THIS PACKAGE ARE CLD TRENDS/SHRA CHCS IN NNW FLOW THAT IS FCST TO PERSIST BTWN RDG TO THE W AND AREA OF LOWER HGTS TO THE E. ONE CHALLENGE WL BE DETERMINING WHETHER ANY DEEPER MSTR TO THE E ASSOCIATED WITH UPR LO JUST S OF JAMES BAY CAN ROTATE FAR ENUF TO THE W TO BRING ANY ENHANCEMENT TO THE LK EFFECT SHRA OVER LK SUP. BOTH THE GFS/NAM HAVE TRENDED STEADILY WWD WITH TRACK/POSITION OF UPR LO S OF JAMES BAY MOVING TO THE SSW. THE 00Z NAM SHOWS THE HIER H7 RH BACKING INTO THE E HALF OF LK SUP BY 00Z THIS EVNG BUT REMAINING JUST TO THE NE OF THE LAND CWA THRU THAT TIME. AT THE SAME TIME...MODEL SHOWS THE LLVL FLOW BACKING MORE NW THRU THE DAY AS A SFC HI CENTER BLDS INTO WI. THIS CHANGE IN FLOW SHOULD ALLOW MORE CLRG OVER THE NCNTRL ZNS AS FLOW OFF LK SUP BECOMES LESS FVRBL BUT MORE CLD OVER THE E. HOWEVER...ANY PCPN SHOULD TEND TO DIMINISH WITH DIURNAL HTG TENDING TO DISRUPT ANY LK EFFECT PCPN AND LOWERING LLVL RH WITH INFUSION OF DRIER AIR FM THE NW/INSOLATION. MIXING TO H85 OR SO ON NAM FCST SDNGS YIELDS HI TEMPS ARND 45 OVER THE HIER TERRAIN OF THE NW TO THE LO 50S OVER THE SCNTRL ARND MNM. TNGT...NAM IS MORE AGGRESSIVE AT BACKING MORE SUBSTANTIAL MSTR SWWD THAN THE GFS. CONSIDERING RECENT MODEL TRENDS IN HI AMPLITUDE BLOCKING PATTERN AS WELL AS WV IMAGERY SHOWING DEEPER MSTR BACKING FARTHER W...WL TEND TOWARD THE NAM FCST SCENARIO. NAM EVEN GENERATES SOME LGT PCPN OVER THE ERN ZNS WHERE LLVL CYC NW FLOW WL HAVE A LONGER FETCH ACRS THE ERN LK IN PRESENCE OF H85 THERMAL TROFFING. ADDED CHC POPS FOR THESE LK EFFECT SHRA OVER AREAS NR LK SUP E OF MUNISING AFT MIDNGT WHEN DEEPER MSTR ARRIVES. TENDED TOWARD THE HIER ETA MOS FOR THE ERN ZNS BUT TOWARD THE LOWER GFS MOS FOR THE INTERIOR W...WHERE SKIES ARE LIKELY TO REMAIN MOCLR IN PRESENCE OF PWAT BTWN 0.25 AND 0.50 INCH. TENDED TOWARD THE SLOWER NAM AGAIN ON SAT WITH MORE MSTR/CLDS/CHC POPS LINGERING OVER THE ERN ZNS WITH PERSISTENT CYC NW LLVL FLOW UNDER DEEPER MSTR. THERE WL BE MORE SUNSHINE OVER THE W...AND MIXING TO H85 ON NAM FCST SDNGS SUPPORTS HI TEMPS IN THE MID-UPR 50S RANGE OVER THE W AND SCNTRL. NAM FINALLY SHOWS CLOSED LO PULLING FAR ENUF TO THE E ON SAT NGT THAT MID LVL MSTR BEGINS TO DEPART THE ERN ZNS. LOOKS LIKE A CHILLY NGT SETTING UP OVER THE INTERIOR W WITH LGT WINDS UNDER SFC RDG AXIS. WL GO NEAR THE LO END OF MOS GUIDANCE IN THESE AREAS BUT NOT TOO CHILLY AS NAM SHOWS PWAT NO LOWER THAN ABOUT 0.45 INCH. PER NCEP GUIDANCE...HAVE TRENDED TOWARD A 00Z CNDN/12Z ECMWF SCENARIO FOR SUN INTO MON. THESE MODELS SHOW A NRN BRANCH SHRTWV MOVING INTO THE UPR GRT LKS ON SUN AND SUPPRESSING POTENT SHRTWV IN THE SRN BRANCH FOR THE MOST PART TO THE S. THIS SCENARIO WOULD ALSO BE MORE CONSISTENT WITH THE MORE BLOCKY UPR PATTERN THAT HAS DVLPD OVER ERN CANADA. TO MESH BETTER WITH SURROUNDING OFFICES...BUMPED POPS UP TO 20 ALG THE WI BORDER AND EVEN TO 30 IN SRN MNM COUNTY ON SUN NGT WHEN CNDN MODEL SHOWS SHRTWV INTERACTING WITH SOMEWHAT HIER MSTR OVER WI. MAINTAINED DRY FCST FARTHER N WHERE DRY AIR WL BE MORE RESILIENT. TENDED TO DCRS CLD COVER ON MON WITH HI PRES UNDER UPR RDGING IN SCNTRL CAN BLDG INTO THE UPR LKS PER CNDN MODEL AND MOST RECENT NCEP MANUAL GUIDANCE. COORDINATED WITH APX/GRB/DLH. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... CIGS WILL CONTINUE MVFR/VFR AT KCMX AND KSAW WHILE LONGER INTO THIS EVENING WITH LAKE EFFECT CLOUDS CONTINUING TO AFFECT THE SITE THROUGH THEN UNTIL THE WIND TURNS WEST AND STARTS BRINGING A BIT OF DRIER AIR IN. WITH DIURNAL HEATING AGAIN SAT MORNING...VFR/MVFR DECK WILL REFORM AGAIN WITH SOME LAKE CONTRIBUTION TO HELP FORM THE CLOUDS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT THE PRES GRADIENT TO TIGHTEN TODAY INTO SATURDAY OVER ERN LAKE SUPERIOR AS A MID LEVEL AND SURFACE LOW DROP SOUTH THROUGH ERN ONTARIO AND THE SFC RDG FROM HUDSON BAY TO THE UPPER MISSISSIPPI VALLEY REMAINS IN PLACE. SO...NW WINDS WILL BACK NW AND INCREASE TO 15 TO 25 KT TODAY AND TO 30 KT LATE TONIGHT AND SATURDAY OVER THE EAST HALF PUSHING WAVE HEIGHTS INTO THE 5 TO 8 FT RANGE. WINDS WILL DIMINISH SAT NIGHT INTO SUN AS HIGH PRES BUILDS INTO THE REGION. E TO NE WINDS WILL DEVELOP FROM MON INTO TUE AS LOW PRES OVER THE CENTRAL PLAINS GRADUALLY SLIDES TO THE ENE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...KC AVIATION...MICHELS MARINE...JLB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
111 PM EDT FRI OCT 12 2007 .SYNOPSIS... LOW PRESSURE ALONG THE MID ATLANTIC COAST WILL MOVE NORTHEAST TO MAINE TODAY. A RIDGE OF HIGH PRESSURE OVER THE WESTERN GREAT LAKES WILL BUILD EAST ACROSS THE OHIO VALLEY OVER THE WEEKEND. LOW PRESSURE WILL RAPIDLY APPROACH FROM THE WEST ON MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... TAMDAR DATA INDICATING LOW LEVEL MOISTURE STILL HANGING ON...DRIER AIR WILL TRY TO WORK INTO WESTERN AREAS THIS AFTERNOON AND SO WENT BECOMING PARTLY SUNNY. EASTERN AREAS MAY SEE SOME BREAKS SO WENT WITH MOSTLY CLOUDY WITH SOME SHOWERS. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... NEUTRAL TEMP ADVECTION WILL CONTINUE TONIGHT WITH 850 MB TEMPS AROUND 0 DEG. W TO NW FLOW EXPECTED TONIGHT SO WILL MAINTAIN SMALL CHANCE POPS FOR NE OH AND NW PA INTO SAT. REALISTICALLY...BEST CHANCES FOR ADDITIONAL PRECIP WILL BE BEFORE MID AS 850 MB FLOW ACTUALLY TRIES TO BECOME ANTICYCLONIC SATURDAY MORNING. 850 MB TEMPS SHOULD MANAGE A GOOD 2 TO 3 DEG RISE BY 00Z SUN SO IT SHOULD BE A LITTLE WARMER ON SAT THAN TODAY. MORE SUN ALSO EXPECTED. CANNOT RULE OUT A FEW SPRINKLES OR LIGHT SHRA IN NW PA BUT PRECIP AMOUNTS WILL BE MINIMAL. THE NEXT COUPLE OF NIGHTS WILL BE CHILLY AND MAY HAVE TO WORRY ABOUT SOME FROST LATER TONIGHT IF WINDS DIE DOWN. WILL LET DAY CREW TAKE A GOOD LOOK AT THAT. WILL UNDERCUT GUID TEMPS FOR SUN AM AS WELL AND MOS FORECASTS IN THE LOWER 40S SEEM A TAD WARM GIVEN AIRMASS. && .LONG TERM /SUNDAY THROUGH FRIDAY/... MODELS CONTINUE TO DEVELOP SPLIT FLOW ALOFT ACROSS THE CONUS...BUT DIFFER SIGNIFICANTLY ON EXACT LOCATION AND MOVEMENT OF SFC FEATURES. GFS AND DGEX DIFFER FROM YDY...BUT ARE IN CLOSE AGREEMENT. BOTH MOVE A LOW PRESSURE SYSTEM ACROSS NORTHERN ILLINOIS TUESDAY...AND THEN WEAKENS AS IT MOVES ACROSS OHIO ON WEDNESDAY. HPC PREFERS ECMWF SOLUTION WHICH IS SIMILAR TO THE GFS ENSEMBLE SOLUTION. LARGE AREA OF HIGH PRESSURE REMAINS INTACT ACROSS GREAT LAKES. SFC LOW FROM MISSOURI ON TUESDAY...ACROSS LOWER MISSISSIPPI VALLEY AS A TROUGH ON WEDNESDAY. DO PUT IN CHC POPS ON WEDNESDAY. && .AVIATION /18Z FRIDAY THROUGH TUESDAY/... LAKE EFFECT CLOUDS CONTINUE THIS AFTERNOON AS 850MB COLD AIR ADVECTION OCCURS ACROSS THE LAKE. 12Z MODEL SOUNDING DATA SHOWS STRONG INVERSION AROUND 5-6KFT WITH LCL AROUND 3-4KFT. CLOUD BASE 5-6KFT FOR MOST OF THE AFTERNOON AND EVENING. WITH A FEW PEEKS OF SUN A FEW DIURNAL CLOUDS AROUND 3-4KFT WL FORM. CEILINGS IN THE EAST COULD BECOME BKN 2-3KFT WITH LAKE EFFECT RAIN SHOWERS AND CLOUDS. AREAS TO THE WEST MAY HAVE BRIEF BKN SKIES 3-4KFT WITH DIURNAL CU. CYCLONIC FLOW TO BECOME MORE WESTERLY OVERNIGHT. A GRADUAL CLEARING TREND WILL OCCUR FROM W TO E ACROSS THE AREA. I WILL HOLD ON TO CLOUDS MOST OF THE NIGHT IN THE EAST. OUTLOOK... INSTABILITY CLOUDS WILL CONTINUE INTO EARLY SATURDAY. VFR CONDITIONS WILL BUILD OVER THE REGION SUNDAY THROUGH TUESDAY AS SOUTHWEST FLOW RETURNS AND HIGH PRESSURE BUILDS. && .MARINE... SURFACE LOW PULLING OUT WELL TO THE EAST OF THE AREA WILL ALLOW WINDS TO SUBSIDE DURING THE DAY TODAY. CYCLONIC FLOW WILL CONTINUE WITH NORTHWEST FLOW THROUGH THE DAY. WINDS SHOULD BE STRONG ENOUGH TO PRODUCE SMALL CRAFT ADVISORY WAVES ON THE LAKE SO WILL CONTINUE THE ADVISORY TODAY. AS HIGH PRESSURE BUILDS SOUTH OF THE AREA...LOW PRESSURE WILL SLIDE SOUTH TOWARD THE LAKE FROM CENTRAL QUEBEC. THE COMBINATION OF THE TWO WEATHER FEATURES WILL TIGHTEN UP THE GRADIENT ACROSS THE LAKE ONCE AGAIN ON SATURDAY. WINDS WILL ONCE AGAIN DIMINISH AS THE HIGH PRESSURE CENTER TRIES TO BUILD BACK NORTH ACROSS THE LAKE SATURDAY NIGHT INTO SUNDAY. WARM FRONT LIFTS NORTH OF THE LAKE SUNDAY NIGHT AND SOUTH TO SOUTHWEST FLOW DEVELOPS AND INCREASES INTO TUESDAY WITH CYCLONIC FLOW IN ADVANCE OF DEEP LOW MOVING NORTHEAST INTO THE CENTRAL GREAT LAKES. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LEZ142>149. && $$ SYNOPSIS...THOMPSON NEAR TERM...THOMPSON SHORT TERM...KUBINA LONG TERM...DJB AVIATION...GARNET MARINE...LOMBARDY