Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 020755
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
355 AM EDT SAT AUG 2 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 354 AM EDT SAT AUG 2 2014

00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW NW FLOW ALF OVER
THE UPR LKS BTWN CLOSED LO IN QUEBEC AND MEAN RDG OVER THE ROCKIES.
SHRTWV EMBEDDED IN THIS FLOW THAT BROUGHT SOME ISOLD SHOWERS/TS TO
THE U.P. LAST EVNG HAS PASSED TO THE E NOW...GIVING WAY TO A SHRTWV
RDG STRETCHING FM NW ONTARIO THRU NRN MN. THERE IS QUITE A CONTRAST
IN AIRMASSES OVER THE UPR LKS WITH 00Z RAOB FM GRB SHOWING PWAT UP
TO 1.07 INCH AND FAIRLY UNSTABLE LAPSE RATES/KINX 31 WHICH SUPPORTED
LAST EVNG`S CONVECTION. ON THE OTHER HAND...THE 00Z INL RAOB
REPRESENTATIVE OF THE INCOMING AIRMASS IS QUITE DRY AND STABLE...
WITH PWAT 0.47 INCH AND KINX 1. CLDS AND EVEN AN ISOLD SHOWER OR TWO
ASSOCIATED WITH THE EXITING SHRTWV ARE STILL OVER ERN UPR MI...BUT
SKIES ARE NOW MOCLR OVER THE W AND THRU NRN MN AS THE DRIER AIR/DNVA
AHEAD OF THE SHRTWV RDG ARE DOMINATING. SOME FOG HAS FORMED AT SOME
OF THE COOLER INTERIOR LOCATIONS. BEHIND THE SHRTWV RDG...THERE IS
ANOTHER DISTURBANCE NEAR LK WINNIPEG DROPPING SEWD ACCOMPANIED BY
SOME SHOWERS/TS.

MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE TEMPS TODAY AND THEN
SHOWER/TS CHCS TNGT AS DISTURBANCE NOW NEAR LK WINNIPEG APRCHS.

TODAY...SHRTWV RDG AXIS/ACCOMPANYING MID LVL DRY AIR IS FCST TO
DRIFT ACRS THE UPR LKS TDAY. DESPITE THE LARGE SCALE SUBSIDENCE/DRY
AIR SHOWN ON THE 00Z INL RAOB...A FEW OF THE MODELS PERSIST IN
GENERATING SOME SHOWERS OVER PORTIONS OF THE CWA. THIS PCPN SEEMS
RELATED TO SOME RELATIVELY WEAK H85 THETA E ADVCTN THAT IS FCST TO
ARRIVE IN THE AFTN AS THE H85 FLOW BACKS TOWARD THE WSW FOLLOWING
THE PASSAGE OF THE HI CENTER TO THE E. BUT GIVEN THE MID LVL
INVRN/DRY AIR IN THE FCST SDNGS THAT IS CONSISTENT WITH THE OBSVD
INL RAOB...OPTED TO KEEP UPR MI DRY AND JUST FCST SOME INCRSG HI
BASED CU/AC ACCOMPANYING THE MARGINAL MSTR RETURN. FCST H85 TEMPS UP
TO 14C OVER THE W BY 00Z AND MIXING TO H8 AS OBSVD ON THE INL RAOB
WL SUPPORT HI TEMPS REACHING THE LO 80S OVER THE INTERIOR W. THIS
DEEP MIXING WL ALLOW SFC DEWPTS TO MIX OUT AS LO AS ARND 50...
DROPPING MIN RH TO AS LO AS ARND 30 PCT. BUT LGT WINDS WL RESTRICT
ANY FIRE WX CONCERNS.

TNGT...AS SHRTWV NEAR LK WINNIPEG TRACKS ESEWD THRU NW ONTARIO...
COMMA TAIL FEATURE/AXIS OF H85-5 QVECTOR CNVGC/SOME MID LVL MOISTER
AIR IS FCST TO TRACK ACRS UPR MI. BUT SINCE THE SHARPER FORCING IS
FCST TO REMAIN TO THE N IN ONTARIO CLOSER TO THE SHRTWV TRACK... THE
INFLUX OF H85 THETA E IN ADVANCE OF THE ATTENDANT COLD FNT IS RATHER
WEAK/SSI FCST NO LOWER THAN ZERO TO -1C AND THESE DYNAMICS WL BE
ARRIVING DURING NOCTURNAL COOLING...SUSPECT THERE WL BE ONLY SOME
SCT SHOWERS MAINLY LATE OVER THE W CLOSER TO THE APRCHG COLD FNT.
GOING FCST APPEARS TO HAVE A GOOD HANDLE ON THE EXPECTED TRENDS AND
WL NEED LTL MODIFICATION.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 325 PM EDT FRI AUG 1 2014

THE LATTER PORTION OF THE WEEKEND BEGINS WITH AN UPPER LEVEL TROUGH
OVER THE GREAT LAKES REGION...AND A RIDGE ANCHORED FIRMLY OVER THE
WESTERN UNITED STATES. THIS PUTS UPPER MICHIGAN IN SOMEWHAT ZONAL
FLOW BEFORE A SHORTWAVE SWEEPS INTO ONTARIO SATURDAY AFTERNOON. THE
GFS/NAM ARE STILL PUSHING THE ASSOCIATED COLD FRONT THROUGH THE CWA
SLIGHTLY EARLIER THAN THE GEM/ECMWF. SHOULD THE FRONT COME IN
EARLIER AS THE GFS/NAM SUGGEST...EXPECT PRECIPITATION TO ENTER THE
WESTERN CWA BY ABOUT 9Z. SHOULD THE ECMWF/GEM SOLUTION BE
CORRECT...TIMING WILL BE SLIGHTLY LATER FOR PRECIPITATION...LIKELY
AROUND 12Z-15Z. WILL GO WITH A COMPROMISE FOR POPS TO RESOLVE THE
MINOR TIMING DIFFERENCES FOR NOW...THOUGH I LEAN MORE TOWARDS THE
SLOWER TIMING OF THE ECMWF/GEM.

AS FAR AS THUNDERSTORM POTENTIAL...BEST CHANCES LOOK TO BE EARLY
SUNDAY AFTERNOON WITH DAYTIME HEATING AS THE FRONT ROLLS THROUGH.
THE BEST INSTABILITY...AROUND 1500-2000 J/KG...LINGERS ALONG THE WI
BORDER. OTHERWISE...MOST OF THE WESTERN AND NORTH CENTRAL CWA SEES
AROUND 500 J/KG. THE ECMWF/GEM KEEP LOWER INSTABILITY ACROSS THE
EAST...LESS THAN 100 J/KG....BUT THE GFS BRINGS THE HIGHER
INSTABILITY OF AROUND 1500 J/KG INTO THE INLAND EAST...AND GENERATES
CONVECTION ALONG THE LAKE BREEZE BOUNDARY. WILL KEEP SCHC THUNDER IN
THAT AREA FOR NOW GIVEN THE DISCREPENCY. AS FAR AS SHEAR
GOES...0-6KM FOR MOST OF THE CWA IS AROUND 15-20 KNOTS...SO WOULD
NOT BE SURPRISED TO SEE A COUPLE STRONGER STORMS DEVELOP IF THE
FRONT PASSES THROUGH WHEN THE BEST INSTABILITY IS IN PLACE.
THUNDERSTORM POSSIBILITY ENDS WITH DAYTIME HEATING...BUT WILL KEEP
CHANCES FOR PRECIPITATION IN THE EAST WITH THE PASSING FRONT...AGAIN
GOING WITH THE CONSENSUS FOR POPS GIVEN THE DISCREPANCIES BETWEEN
NAM/GFS AND THE ECMWF/GEM.

MONDAY THE RIDGE BUILDING ACROSS THE WESTERN CONUS AND CANADIAN
PRAIRIE WILL EXPAND INTO THE WESTERN CWA...WITH SURFACE HIGH
PRESSURE FORCING ITS WAY INTO UPPER MI. MODELS ALSO DEVELOP A LOW
PRESSURE SYSTEM OVER NEBRASKA/SOUTH DAKOTA THAT DRAPES A WARM FRONT
ACROSS WI AND IOWA. MODEL DIFFERENCES AGAIN BRING COMPLICATION TO
THE FORECAST...WITH THE GFS/GEM HAVING STRONGER SURFACE HIGH
PRESSURE THAT KEEPS THE LOW/WARM FRONT FURTHER SOUTH...AND ALL
PRECIPITATION ONLY UP TO THE WI BORDER. THE ECMWF BRINGS THE LOW AND
WARM FRONT FURTHER NORTH...AND GENERATES CONVECTION MONDAY AFTERNOON
INTO SOUTHERN UPPER MI. WILL KEEP GOING SLIGHT CHANCE POPS/CONSENSUS
FORECAST NEAR THE WI BORDER/SOUTH CENTRAL U.P. FOR NOW.

STRONG SFC HIGH PRESSURE CENTERS ITSELF OVER THE GREAT LAKES FOR
TUESDAY AND LINGERS OVER THROUGH WEDNESDAY...THOUGH AT UPPER LEVELS
THE TROUGH STILL LINGERS AND KEEPS 850MB TEMPS AROUND 10-12C. THIS
WILL KEEP THINGS A BIT COOLER THAN NORMAL...ESPECIALLY WITH LIGHT
WINDS ALLOWING FOR LAKE BREEZE DEVELOPMENT. OVERALL...EXPECT A DRY
FORECAST FOR THESE DAYS WITH HIGHS IN THE UPPER 60S NEAR THE
LAKE...AND THE LOW TO MID 70S INLAND.

IN THE MEANTIME...A POTENT 500MB SHORTWAVE DEVELOPS OVER THE
CANADIAN PRAIRIES WEDNESDAY MORNING DIGS DEEPER INTO THE NORTHERN
PLAINS BY WEDNESDAY EVENING. THIS AMPLIFIES THE RIDGE AND SHIFTS IT
EASTWARD FROM THE UPPER MISSISSIPPI VALLEY WEDNESDAY INTO UPPER
MICHIGAN FOR THURSDAY. SFC LOW PRESSURE DEVELOPS WITH THIS
SHORTWAVE...THOUGH THE ECMWF/GFS ONCE AGAIN DIFFER ON THE PLACEMENT
AND MOVEMENT OF THIS LOW. THE GFS DEVELOPS IT OVER THE NORTHERN
PLAINS AND MOVES IT INTO ONTARIO...AND THE ECMWF DEVELOPS IT OVER
IOWA AND MOVES IT INTO WISCONSIN. WILL STICK WITH CONSENSUS POPS YET
AGAIN THURSDAY INTO FRIDAY DUE TO THE LARGE DIFFERENCES.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 122 AM EDT SAT AUG 2 2014

VFR CONDITIONS ARE EXPECTED TO PREVAIL AT ALL THREE TAF SITES OVER
THE NEXT 24 HOURS. THERE WILL BE SOME INCREASE IN SOME MID CLOUDS
OVER THE WRN TAF SITES TOWARD SAT EVENING.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 354 AM EDT SAT AUG 2 2014

WITH A WEAK PRESSURE GRADIENT TYPICAL OF SUMMER DOMINATING THIS
FORECAST PERIOD...EXPECT WINDS UNDER 15 KTS THROUGH WED. ALTHOUGH
THERE WILL BE PATCHY FOG WITH RELATIVELY HUMID AIR OVER THE CHILLY
LAKE WATERS INTO MON...NO WIDESPREAD DENSE FOG IS LIKELY.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...KC
LONG TERM...MCD
AVIATION...VOSS
MARINE...KC





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