Issued by NWS Marquette, MI
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000 FXUS63 KMQT 211715 AAB AFDMQT AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1215 PM EST SAT NOV 21 2009 UPDATED FOR 18Z TAFS .SYNOPSIS... 00Z RAOBS SHOW RDG ALF BLDG INTO THE WRN GRT LKS DOWNSTREAM OF UPR TROFFING ALG THE W COAST. AIRMASS UNDER THIS RDG IS QUITE DRY ALF... WITH 00Z PWAT AS LO AS A MEAGER 0.11 INCH AT INL. SINCE NEAR SFC MSTR IS MORE ABUNDANT...FOG HAS DEVELOPED OVER THE FA WITH LGT WINDS ASSOCIATED WITH SFC HI PRES BLDG OVHD UNDER THE RDGING ALF. THE FOG HAS BECOME LOCALLY DENSE EARLY THIS MRNG. TO THE W...VERY WARM AIR IS FLOODING NWD INTO THE NRN PLAINS IN THE SLY FLOW BTWN THE HI PRES RDG NOW OVHD AND LOWER MSLP IN THE ROCKIES. THE 00Z H85 TEMP RANGED FM 4C AT GRB AND INL TO 9C AT BIS AND AN IMPRESSIVE 14C AT GLASGOW MT. && .DISCUSSION... MAIN FCST CONCERNS THIS FCST PD INCLUDE TEMPS THIS WEEKEND AND THEN PCPN CHCS LATE SUN INTO THE MIDDLE OF NEXT WEEK AS LO PRES BEGINS TO TAKE SHAPE IN THE PLAINS AND MOVES NE. TDAY...UPR RDG WILL CONT TO BLD OVER THE UPR LKS WITH FLOOD OF WARM AIR SURGING INTO CAN AHEAD OF DEEP WRN TROF. WITH DRYNESS OF AIRMASS MOVING OVHD...EXPECT A MOSUNNY DAY AFT MRNG FOG BURNS OFF. ISSUED SPS TO HILIGHT PATCHY DENSE FOG EARLY THIS MRNG. MIXING TO H9 ON FCST SDNGS YIELDS HI TEMPS TOPPING OUT AS HI AS THE LO 50S. GOING FCST MAX TEMPS SEEM ON TRACK. FOR TNGT...AS HI PRES RDG SHIFTS TO THE E...SHARPER PRES GRADIENT/ STRENGTHENING SLY FLOW WL DVLP OVER THE CWA...EARLIEST OVER THE W. WITH THIS STRONGER WIND...EXPECT RELATIVELY LTL DIURNAL FALL OF TEMP IN THE DOWNSLOPING AREAS NEAR LK SUP...ESPECIALLY OVER THE W FM IWD- P59. ALTHOUGH THE SHELTERED INTERIOR ECNTRL WL SEE LOWER TEMPS BLO MOS GUIDANCE WITH DRY MID LVLS AND WEAKER WINDS A BIT LONGER CLOSER TO DEPARTING SFC HI...BUMPED UP GOING FCST MIN TEMPS THERE A BIT WITH BOTH GFS/NAM SHOWING A QUICKER RETURN OF H95-9 SPECIFIC HUMIDITY THAT WL FAVOR FOG AND/OR ST DVLPMENT DURING TIME OF DIURNAL COOLING. GFS REMAINS THE MOST AGGRESSIVE MODEL AT GENERATING PCPN OVER THE W HALF OF THE FA ON SUN AFTN SHOWING MSTR RETURN THRU H7. ALTHOUGH THE NAM NOW SHOWS HIER SPECIFIC HUMIDITY RETURNING AT H7 AS WELL...THIS MODEL FOCUSES THE AXIS OF HIER MSTR FARTHER W OVER WRN LK SUP. CONSIDERING THE FAIRLY HI AMPLITUDE WRN TROF/ERN RDG PATTERN THAT WOULD FAVOR A SLOWER W-E PROGRESSION...TENDED TOWARD THE NAM AND GOING FCST. ALTHOUGH THE EXPLICIT GFS FCST SHOWS PCPN...THE GFS MOS FCST FOR IWD SHOWS ONLY A 10 POP FOR 18Z-24Z SUN...SUPPORTING THE DRIER NAM AND UKMET. OVER THE E...THERE WL LIKELY BE SOME SUNSHINE AFT MRNG FOG/ST BURNS OFF WITH MID LVL DRY AIR THRU THE DAY. MORE PERSISTENT CLD COVER OVER THE W WL LIMIT THE DIURNAL TEMP REBOUND... BUT BUMPED UP FCST HI TEMPS FARTHER E AWAY FM THE MODERATING INFLUENCE OF LK MI WITH EXPECTATION FOR MORE AFTN SUNSHINE. TENDED TO FOLLOW THE LESS PROGRESSIVE NAM/UKMET/12Z ECMWF AGAIN ON SUN NGT AND CUT BACK ON EWD PROGRESSION OF POPS IN PREVIOUS FCST GIVEN STRENGTH OF RDG TO THE E AND LINGERING MID LVL DRY AIR. WENT WITH HIEST POPS OVER WRN LK SUP WHERE NAM SHOWS AXIS OF HIER H85-7 SPECIFIC HUMIDITY AND SOME WEAK UPR DVGC FOR A TIME IN RRQ OF H3 JET MAX LIFTING NEWD THRU NW ONTARIO. OVER THE E...LOWERED GOING FCST MIN TEMPS BLO MOS GUIDANCE GIVEN PERSISTENCE OF DRY AIR ALF AND WHERE NAM SHOWS RISING MSLP/WEAKER GRADIENT FLOW. ALSO ADDED SOME FOG IN THESE AREAS WHERE DRIER AIR/LIGHTER WINDS WOULD FAVOR THE SHARPER DIURNAL TEMP FALL. RAISED FCST MIN TEMPS OVER THE W WITH MORE CLDS/STRONGER WINDS/DOWNSLOPING SLY FLOW. WITH RDG/ACYC FLOW TENDING TO STRENGTHEN ON MON DOWNSTREAM OF DEEPENING TROF IN THE PLAINS...TRIMMED GOING POPS TO FCST SCHC POPS ONLY OVER THE FAR W CLOSER TO LO PRES TROF IN NE MN ON MON AND MON NGT. WITH TENDENCY FOR DRIER AIR...INCRSD MAX TEMPS ON MON AND LOWERED FCST FOR MON NGT MINS. ADDED FOG AGAIN OVER THE INTERIOR ECNTRL WHERE LOWEST TEMPS ARE FAVORED UNDER HIER MSLP. TENDED TO CUT POPS OVER ESPECIALLY THE NE FA ON TUE AS WELL WITH FAVORED 00Z ECMWF STILL SHOWING TENACIOUS DRY AIR THERE THRU 00Z WED CLOSER TO SFC HI IN QUEBEC. COORDINATED WITH GRB. && .AVIATION /FOR THE 18Z TAF ISSUANCE/... MORNING FOG HAS DISSIPATED WITH VFR CONDITIONS EXPECTED AT SAW AND CMX THROUGH THE EVENING HOURS. WITH SFC RIDGE MOVING EAST OF THE AREA AND PRESSURE GRADIENT TIGHTENING...SOUTHERLY WINDS SHOULD PREVENT FOG FROM GETTING AS DENSE AS LAST NIGHT. HOWEVER...WITH LOW LEVEL MOISTURE REMAINING...DO EXPECT SOME FOG TO REDEVELOP AFTER MIDNIGHT...ESPECIALLY UNTIL SOUTHERLY WINDS BEGIN TO INCREASE TOWARDS DAYBREAK. IN ADDITION..EXPECT MVFR STRATUS CIGS TO DEVELOP AT BOTH SITES LATE TONIGHT AND PERSIST THROUGH SUNDAY MORNING. && .MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/... WINDS WILL REMAIN BELOW 25 KNOTS THROUGH THIS FORECAST PERIOD AS HIGH PRESSURE REMAINS OVER THE UPPER GREAT LAKES AND KEEPS SYSTEMS OUT OF THE AREA. WINDS WILL START TO INCREASE WED...POSSIBLY TO GALE FORCE...AS A STORM SYSTEM COMES UP FROM THE SOUTH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...KC AVIATION...MZ MARINE...PEARSON
