000 FXUS63 KMQT 040743 AFDMQT AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 345 AM EDT SAT JUL 4 2009 .SYNOPSIS... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW NW FLOW ALF BTWN PERSISTENT TROF FM HUDSON BAY TO SE ONTARIO AND RDG OVER TX/DESERT SW. THIS NW FLOW IS DRY AS 00Z INL/YPL RAOBS DEPICT A RELATIVELY DRY AIRMASS WITH PWAT 0.61 INCH/0.44 INCH RESPECTIVELY. AT THE SFC...HI PRES EXTENDS FM SCNTRL CAN INTO THE UPR GRT LKS. ALTHOUGH THE FA IS DOMINATED BY A DRY FLOW...SOME HI CLD TO THE NE OF WARM FNT IN THE NCNTRL PLAINS IS NOTED AS FAR N AS NRN MN/THE FA. NEXT SHRTWV OF INTEREST IS OVER SASKATCHEWAN AND BRINGING SOME SHRA/TSRA INTO ERN MONTANA/NW NDAKOTA. && .DISCUSSION... MAIN FCST CONCERNS THIS PACKAGE REVOLVE ARND TEMPS TDAY/TNGT WITH DRY HI PRES TO LINGER. FOCUS FOR LATER IN THE WEEKEND/EARLY NEXT WEEK SHIFTS TO TIMING/PCPN CHCS ASSOCIATED WITH SHRTWV NOW IN SASKATCHEWAN AND OTHER DISTURBANCES FCST TO MOVE THROUGH NW FLOW ALF ARND PERSISTENT TROFFING IN SE CAN. FOR TDAY...EXPECT A FANTASTIC DAY FOR JUL 4TH CELEBRATIONS WITH HI PRES/DRY AIRMASS LINGERING. ALTHOUGH THERE MAY BE SOME HI CLDS ARND THIS MRNG...THIS CLD SHOULD MOVE TO THE S IN THE AFTN AND GIVE WAY TO JUST SOME SCT DIURNAL CU INLAND FM LK STABILIZATION. MIXING TO H75 ON NAM FCST SDNGS YIELDS HI TEMPS IN THE MID/UPR 70S AWAY FM LK MODERATION NEAR THE WI BORDER. WITH LGT NNE H925 FLOW...MODERATION OFF LK SUP WL BE GREATEST. TNGT...SHRTWV NOW OVER SASKATCHEWAN IS PROGGED TO PASS OVER LK SUP. BOTH NAM/GFS GENERATE NO PCPN OVER UPR MI DESPITE SOME DPVA/MODEST MOISTENING IN THE H85-7 LYR WITH RETURN WSW FLOW/H85-5 QVECTOR CNVGC AS FCST SDNGS SHOW LLVLS REMAINING PROBHITIVELY DRY. CONSIDERING THE ABSENCE OF DIURNAL HTG...WL RETAIN GOING DRY FCST. BOTH MODELS SHOW MOST IMPRESSIVE MID LVL MOISTENING OVER THE NRN TIER CLOSER TO TRACK OF DISTURBANCE...SO EXPECT MORE CLD COVER THERE. PLAN ON LOWEST MINS OVER THE INTERIOR SCNTRL WHERE MID CLD WL BE LESS. ON SUN...SHRTWV TRACKING THRU LK SUP IS PROGGED TO SHARPEN UPR TROF OVER ONTARIO. COOLER AIR IS FCST TO SPILL INTO THE UPR GRT LKS... ESPECIALLY OVER THE ERN ZNS WHERE GFS/NAM SHOW H85 TEMP OF 7C AT ERY BY 00Z MON. THE W IS FCST TO BE JUST GLANCED BY THIS COOL SHOT WITH H85 TEMP AT IWD 11C AT THE END OF THE DAY. ALTHOUGH THE GFS IS COMPLETELY DRY...NAM GENERATES SOME LGT PCPN OVER THE SCNTRL AND E INLAND FM LK SUP STABILIZATION MODERATION...WHERE MODEL FCST SDNG FOR ISQ AT 18Z SHOWS SFC-H875 ML CAPE NEAR 250 J/KG. ALTHOUGH THE GFS ALSO HAS SOME MSTR IN THE H8-7 LYR...THE MAIN DIFFERENCE APPEARS TO BE HIER H6 TEMP VS THE NAM...-7C GFS VS -9C NAM. CONSIDERING THE PERSISTENT ERN TROF AND RATHER VIGOROUS APPEARANCE OF SHRTWV NOW OVER SASKATCHEWAN...THE LOWER H6 TEMP SEEMS MOST RSNBL. SINCE PREVIOUS FCST HAD SCHC POPS DURING PD OF DAYTIME HTG...WL RETAIN THESE LO POPS OVER THE E HALF OF THE FA INLAND FM LK SUP. OVER THE W...EVEN THE NAM SHOWS A HI ENUF H6 TEMP/LESS IMPRESSIVE LAPSE RATES TO STUNT SHRA DVLPMNT. OPTED TO BUMP POPS UP A BIT SUN NGT TO 40 OVER THE E AS GFS/NAM SHOW DEEPER MSTR ON WRN FLANK OF CUTOFF LO TO THE E IMPACTING AREAS MAINLY E OF MQT-ESC. THE CONTRAST IN FCST SDNGS TO THE W HOWEVER IS QUITE STRIKING IN TERMS OF MSTR AND STABILITY WITH NAM SHOWING PWAT RANGING FM 1.00 INCH AT ERY TO 0.46 INCH AT IWD AT 06Z MON. ALTHOUGH H85 TEMPS AT ERY ARE PROGGED TO BE LOWER THAN OVER THE W...FVRBL CONDITIONS FOR RADIATIONAL COOLING SUG THE LOWER MIN TEMPS WL BE OVER THE INTERIOR W. NOT SURPRISINGLY WITH FAST NW FLOW ALF...NAM AND GFS BEGIN TO DIFFER ON MON CONCERNING STRENGTH AND IMPACT OF ANOTHER SHRTWV THAT IS FCST TO DIVE SEWD IN NW FLOW ALF TOWARD THE UPR GRT LKS. THE GFS DEPICTS A SOMEWHAT SHARPER SHRTWV THAT DIGS FARTHER W AND GENERATES SOME LGT PCPN OVER THE W HALF OF UPR MI. THE NAM ON THE OTHER HAND SHOWS LARGER SCALE HGT RISES DOMINATING UPR MI ON MON IN THE WAKE OF DEEPER TROF RESPONSIBLE FOR THE PCPN CHCS ON SUN NGT THAT WL BE SLOWLY DEPARTING TO THE E ON MON. SINCE THE 00Z UKMET/CNDN MODELS SHOW A SCENARIO MORE SIMILAR TO THE NAM FCST...WL TEND IN THIS DIRECTION. SO AFT SOME LO CHC POPS OVER THE E IN THE MRNG ASSOCIATED WITH TROF IN SE ONTARIO...WL GO DRY IN THE AFTN. ONLY CHG MADE BEYOND MON NGT WAS TO INTRODUCE CHC POPS LATE TUE NGT AND WED OVER THE W AS GFS MODEL IS FASTER BRINGING A RETURN OF WAD PCPN INTO THE UPR GRT LKS. BUT 0Z GFS APPEARS TO SUFFER CONVECTIVE FEEDBACK WITH DEEP LO PRES IT DRIVES TOWARD UPR MI...SO WAS MUCH LESS AGGRESSIVE PUSHING POPS EWD AS FAST AS THAT EXPLICIT MODEL GUIDANCE WOULD SUG. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... DRY AIR OVER THE AREA WILL ENSURE VFR CONDITIONS AT KCMX/KSAW THRU THIS FCST PERIOD AND WELL BEYOND AS HIGH PRESSURE BUILDS IN. CALM/LIGHT WINDS OVERNIGHT WILL BECOME LAKE BREEZE INFLUENCED AT AROUND 10KT BY LATE MORNING/EARLY AFTN. && .MARINE (FOR THE 4 AM LAKE SUPERIOR ISSUANCE)... HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE UPPER GREAT LAKES REGION THROUGH MONDAY...AND THEN WILL SLOWLY DRIFT EAST AS A LOW PRESSURE AREA APPROACHES LAKE SUPERIOR FROM THE WEST MID WEEK. UNDER THE INFLUENCE OF THE HIGH PRESSURE SYSTEM...WINDS ARE TO REMAIN AT SPEEDS LESS THAN 20 KNOTS WITH WAVES CALM TO THREE FEET. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...KC AVIATION...ROLFSON MARINE...RJT