652 FXUS63 KMQT 261740 AFDMQT AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1240 PM EST TUE FEB 26 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 357 AM EST TUE FEB 26 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW PATTERN ACRS NAMERICA...WITH THE UPR GRT LKS UNDER A POLAR JET STREAM WELL S OF ARCTIC BRANCH IN CENTRL CANADA THAT HAS CONFINED THE BITTERLY COLD ARCTIC AIR TO FAR NRN CANADA. AN ACTIVE SUBTROPICAL BRANCH DOMINATES THE S HALF OF THE CONUS...WITH A POTENT DISTURBANCE MOVING INTO THE LOWER-MID MS RIVER VALLEY. A DISTURBANCE WITHIN THE POLAR BRANCH IS MOVING ACRS UPR MI EARLY THIS MRNG...BUT LIMITED MSTR DEPTH PER 00Z GRB/APX RAOBS AND GENERAL LARGER SCALE ACYC FLOW RELATED TO RDG AXIS EXTENDING WWD FM HI CENTER IN SE CANADA HAS RESTRICTED ANY IMPACT TO AN AREA OF SC. THE BACK EDGE OF THIS CLD AREA IS JUST INLAND FM THE W SHORE OF UPR MI CLOSER TO INCOMING AREA OF DRY AIR DEPICTED ON THE 00Z INL/MPX RAOBS AND WHICH IS UNDER DNVA/LARGE SCALE QVECTOR DVGC BEHIND THE SHRTWV. SKIES OVER FAR NW WI/WRN LK SUP AND THE MN ARROWHEAD OF MOCLR...WHICH HAS ALLOWED SOME FOG TO FORM WITH LGT WINDS. HI CLDS ON THE NRN EDGE OF THE SUBTROPICAL BRANCH DISTURBANCE TO THE S ARE SPREADING SLOWLY NWD THRU WI. MAIN FCST CONCERNS TODAY ARE CLD TRENDS/IMPACT ON TEMPS. FOCUS FOR TNGT SHIFTS TO WHETHER ANY PCPN ASSOCIATED WITH SRN BRANCH DISTURBANCE WL IMPACT THE SRN CWA. TODAY...POLAR BRANCH UPR RDG/DNVA/LARGE SCALE QVECTOR DVGC WL DOMINATE UPR MI TODAY. AS THE SUBTROPICAL BRANCH SFC LO MOVES INTO THE LOWER OH RIVER VALLEY BY 00Z WED...THE PRES GRADIENT WL TIGHTEN OVER UPR MI TO THE WSW OF HI CENTERED IN SE CANADA...WITH AN INCRSG ENE FLOW. ALTHOUGH THE LARGER SCALE NEGATIVE DYNAMICS WOULD INDICATE A SLOW BREAKUP OF THE SC DOMINATAING MUCH OF THE CWA NOW...THIS LO CLD IS WIDESPREAD TO THE E OF UPR MI THIS MRNG...THE SOURCE AIRMASS FOR THE DVLPG E WIND. ON THE OTHER HAND...THE DIFFLUENT NATURE OF THE LLVL FLOW AS WELL AS STRONG SUBSIDENCE FCST AT H925 SHOULD TEND TO BREAK UP THE LO CLD. RECENT TRENDS SHOWN ON STLT IMAGERY/SFC OBS CONFIRM THIS EXPECTATION. DIURNAL HEATING WITH INCRSG LATE FEB SUN ANGLE WL ALSO TEND TO DISSIPATE THE SC OVER THE LAKES AS H85 TEMPS ARE FCST TO BE ABOUT -4C...A TYPICAL EARLY SPRING SCENARIO. IN THIS SCENARIO...SOME DIURNAL CU/SC WOULD TEND TO FORM OVER THE INTERIOR FOLLOWING INITIAL CLRG. THE COVERAGE OF THIS CLD SHOULD BE LIMITED BY THE RATHER LO INVRN BASE SHOWN ON NAM/GFS FCST SDNGS. MAINTAINED OVERALL FLAVOR OF GOING FCST SHOWING A TERND FOR DECREASING CLDS INTO THIS AFTN...WITH A BIT MORE CLD COVER OVER THE INTERIOR... ESPECIALLY IN USPLOPE AREAS. MIXING TO H875 ON FCST SDNGS YIELDS HI TEMPS CLOSE TO 40...MOST LIKELY IN AREAS OVER THE W THAT SEE MORE SUNSHINE AND DOWNSLOPE IN LLVL ENE FLOW AWAY FM THE COOLING INFLUENCE OF THE LKS. GOING FCST NEEDS ONLY MINOR ADJUSTMENTS. TNGT...SUBTROPICAL BRANCH LO IS PROGGED TO MOVE NE INTO OH BY 12Z WED. THE BULK OF THE NUMERICAL GUIDANCE SHOWS LGT QPF ON THE NW FLANK OF THIS LO PRES BRUSHING JUST THE SE COUNTIES WITH SOME LGT PCPN TOWARD 12Z WED...CONSISTENT WITH THE PASSAGE OF THE DEEP LYR QVECTOR THRU LWR MI. DESPITE CYC NATURE OF THE INCRSG LLVL NE FLOW...H85 TEMPS NO LOWER THAN ABOUT -5C AS WELL AS FCST DRY H85-7 LYR INDICATE THERE WL BE NO LK EFFECT/ENHANCED PCPN EVEN IF MORE SC DVLPS IN THE UPSLOPE AREAS. OPTED TO RETAIN GOING SCHC POPS ONLY CLOSE TO LK MI/BAY OF GREEN BAY. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 357 AM EST TUE FEB 26 2013 NOT MUCH IN THE WAY OF PRECIPITATION EXPECTED THROUGH THIS LONG TERM PERIOD...WITH MARCH LIKELY COMING IN LIKE A LAMB /AS NOTED ON THE PREVIOUS DISCUSSION/. BY WEDNESDAY THE 500MB LOW WILL BE THE CLOSEST IT WILL GET TO THE CWA...TRACKING FROM OHIO TO NE PENNSYLVANIA...SQUEEZING THE RIDGE NORTH INTO ONTARIO. EXPECT NE FLOW AT THE SFC AND ALOFT WEDNESDAY. THE 25/12Z CONTINUES TO SHOW A SOUTHERLY TREND TO THE TRACK...WITH A DOUBLE BARREL LOW SPLITTING THE APPALACHIANS MERGING ACROSS THE NEW ENGLAND STATES WEDNESDAY NIGHT. A MEER 24 HOURS AGO THE NAM SOLUTION WAS FOR THE SURFACE LOW TO SWING ACROSS CENTRAL LOWER MICHIGAN...NOW IT LOOKS TO BE MORE IN LINE IF NOT SLIGHTLY SLOWER THAN THE ECMWF/GFS ON WEDNESDAY. STRONG HIGH PRESSURE STRETCHING ACROSS NORTH CENTRAL CANADA ON TUESDAY WILL PUSH INTO HUDSON BAY AND MANITOBA/ONTARIO WEDNESDAY/WEDNESDAY NIGHT...WITH THE RIDGE EDGING ACROSS LAKE SUPERIOR THURSDAY NIGHT THROUGH AT LEAST SUNDAY MORNING. WE STILL EXPECT SOME BREEZY CONDITIONS NEAR THE LAKE SUPERIOR SHORELINE WEDNESDAY THROUGH THURSDAY /PUSHING ACROSS MUCH OF CENTRAL UPPER MICHIGAN DURING THE DAY THURSDAY/. WINDS WILL SLOWLY DIMINISH AS THE LOW CONTINUES TO EXIT EAST AND THE SURFACE HIGH PUSHES OVERHEAD. AS FOR THE CHANCE OF PRECIPITATION THROUGH THE PERIOD...IT IS PRETTY MINIMAL. THE SYNOPTIC SNOW WILL ONLY CLIP AREAS NEAR LAKE MICHIGAN WEDNESDAY INTO WEDNESDAY EVENING. EVEN WITH THE FAVORABLE UPSLOPE WINDS OFF LAKE SUPERIOR...TEMPERATURES AT AND ABOVE THE SURFACE WILL BE MARGINAL TO SUPPORT ANY ACCUMULATING SNOW SHOWERS. COLDER AIR WILL FINALLY COME IN FOR THE END OF THE WORK WEEK...WITH 850MB TEMPERATURES FALLING TO AROUND -11C FRIDAY AFTERNOON...AND -12 TO -14C FRIDAY NIGHT THROUGH AT LEAST SUNDAY /WITH N-NE WINDS CONTINUING THROUGH SATURDAY/. THE 25/12Z ECMWF KEEPS THE RIDGE IN PLACE THROUGH TUESDAY...BECOMING OUT OF PHASE WITH THE 25/18Z GFS BY MONDAY NIGHT /STRONG 1044MB HIGH OVER NORTHERN MANITOBA AND ONTARIO...COMPARED TO THE 1005MB LOW ACROSS ONTARIO/. WHILE THE 26/00Z GFS DID COME IT SLIGHTLY BETTER AGREEMENT...IT JUST CAN NOT BEAT THE RUN TO RUN CONSISTENCY BEING SHOWN BY THE ECMWF. CUT BACK THE SLIGHT CHANCE POPS GIVEN WITH A CONSENSUS OF THE MODELS FOR DAY 6/MONDAY TO RIGHT ALONG THE WISCONSIN BORDER...MINIMIZING THE INFLUENCE OF THE 26/00Z GFS RUN ON THE POPS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1240 PM EST TUE FEB 26 2013 AT KIWD...EXPECT VFR CONDITIONS THRU THE AFTN. HOWEVER...DAYTIME HEATING HAS LEAD TO OCNL BKN CIGS DEVELOPING OVER WRN UPPER MI PER SATELLITE IMAGERY. SO THERE MAY BE A FEW PERIODS OF MVFR CIGS THIS AFTN AT KIWD. KCMX HAS A SIMILAR SETUP TO KIWD...BUT WILL KEY ON LARGE AREA OF STRATOCU OVER ERN LAKE SUPERIOR WHICH IS MAKING STEADY PROGRESS WESTWARD. SIMPLE EXTRAPOLATION SUGGESTS MVFR CIGS MAY REACH KCMX AROUND 22Z. AT KSAW...EXPECT HIGH MVFR CIGS TO RISE SLIGHTLY TO VFR DURING THE AFTN HRS. TONIGHT INTO WED MORNING...LOW PRES MOVING TOWARD THE LOWER LAKES WILL CAUSE A CYCLONIC NE FLOW TO STRENGTHEN. THIS SHOULD RESULT IN MVFR CIGS DEVELOPING WHERE THIS FLOW MOISTENED BY LAKE SUPERIOR WILL UPSLOPE AT KIWD/KSAW. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 357 AM EST TUE FEB 26 2013 A RIDGE OF HIGH PRESSURE ACROSS LAKE SUPERIOR WILL PUSH NORTHWARD TODAY...IN ADVANCE OF WEAKENING LOW PRESSURE SLIDING FROM SOUTHERN MISSOURI THIS MORNING TO FAR SOUTHEASTERN LOWER MICHIGAN AND OHIO WEDNESDAY MORNING...AND EXITING ACROSS NEW YORK WEDNESDAY NIGHT. AS A RESULT...EXPECT A TROUGH OVER LAKE SUPERIOR WITH STEADY N-NE WINDS FROM MID AFTERNOON THROUGH THE REST OF THE WORK WEEK. THE STRONGEST WINDS...WITH A FEW GUSTS NEARING 35KTS CAN BE EXPECTED WEDNESDAY INTO THURSDAY AS LAKE SUPERIOR BECOMES PINNED BETWEEN THE LOW PRESSURE SYSTEM TO OUR SOUTHEAST AND STRONG HIGH PRESSURE EDGING IN FROM THE NORTHWEST. GIVEN THE STRONGER WINDS AND COOLER AIR SLIDING IN...FREEZING SPRAY WILL BE POSSIBLE. HIGH PRESSURE WILL WIN OUT FRIDAY...WITH A RIDGE RESIDING ACROSS LAKE SUPERIOR THROUGH AT LEAST SATURDAY NIGHT. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...KF AVIATION...ROLFSON MARINE...KF