Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 270524
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
124 AM EDT WED AUG 27 2014

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 305 PM EDT TUE AUG 26 2014

WV LOOP AND 12Z RAOBS INDICATE WSW FLOW ALOFT OVER THE UPPER GREAT
LAKES DOWNSTREAM OF TROUGH OVER THE WESTERN CONUS. PRIMARY COLD
FRONT SETTLING TO THE SOUTH AND EAST OF CWA IS ALLOWING FOR A MUCH
COOLER CANADIAN AIRMASS TO ADVECT OVER THE UPPER GREAT LAKES. H85
THERMAL TROUGH WITH TEMPS DOWN TO +5C ALONG WITH GUSTY ONSHORE WINDS
ARE KEEPING TEMPS NEAR LK SUPERIOR AROUND 60 DEGREES THIS AFTN WITH
READINGS TO NEAR 70 DEGREES FARTHER INLAND AND TOWARD DOWNSLOPING
NEAR LK MICHIGAN. A LOT OF LOW-MID CLOUDS DUE TO THE THERMAL TROUGH
HAVE ALSO HELD DOWN DAYTIME TEMPS SOME 15-20 DEGREES LOWER THAN WHAT
WAS OBSERVED ON MONDAY AFTN. PLAN FOR A PERSISTENCE FORECAST INTO
EARLY THIS EVENING...WITH DIMINISHING TREND FOR BOTH WINDS AND
CLOUDS.

UPSTREAM...WV LOOP SHOWS SHORTWAVE WITH DECENT DRYING IN ITS WAKE
OVER SOUTHERN SASKATCHEWAN. AS THIS WAVE MOVES EAST ACROSS LK
SUPERIOR LATER TONIGHT IT SHOULD DEEPEN SLIGHTLY. THE LIFT FM THE
WAVE ALONG WITH AN AREA OF MID-LEVEL CLOUDS TIED TO RIGHT ENTRANCE
REGION OF H3 JET STREAK FM ND TO LK SUPERIOR ARE FORECAST TO SYNC UP
OVERNIGHT TO POSSIBLY PRODUCE A FEW SHOWERS. PRIME NEGATIVE FACTOR
AS HIGHLIGHTED BY PREVIOUS SHIFT WILL BE DRY AIR BLO H9 THANKS TO
SFC RIDGE CENTERED OVER MINNESOTA. NAM/GFS AND GEM-REGIONAL SHOW
BEST MID-LEVEL MOISTURE MAINLY OVER WEST HALF OF CWA 06Z-12Z. GIVEN
DECENT UVM IN THE MOIST LAYER ALOFT...PUT A MENTION OF SPRINKLES IN
OVERNIGHT. SIGNIFICANT DRYING BEHIND SHORTWAVE PUTS KABOSH ON ANY
MOISTURE AND WEAK LIFT TOWARD 12Z OVER NW CWA AND BY 15Z ACROSS REST
OF CWA SO REALLY DECREASED CLOUD COVER INTO WEDNESDAY MORNING.
DESPITE SUNSHINE...PERSISTENT THERMAL TROUGHING WITH H85 TEMPS AS
LOW AS +4C OVER LK SUPERIOR SHOULD KEEP TEMPS IN THE 60S NORTH HALF
AND INTO THE LOWER 70S OVER THE SOUTH. LOWEST TEMPS...AROUND THE 60
DEGREE MARK...NEAR LK SUPERIOR FROM MUNISING TO GRAND MARAIS WITH
NORTH TO NORTHWEST ONSHORE WINDS.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 352 PM EDT TUE AUG 26 2014

AS HAS BEEN THE CASE THE LAST SEVERAL DAYS...FCST CONCERNS IN THE
MIDDLE/LONGER TERM WL FOCUS ON THE INTERACTION BTWN A FAIRLY ZONAL
NRN BRANCH FLOW OVER SRN CANADA/A WEAKER SRN BRANCH FLOW OVER THE
CONUS AND POTENTIAL FOR PCPN ACRS UPR MI. THE BULK OF THE LATEST
MODEL GUIDANCE HINTS THE SE CWA WL BE IMPACTED MOST BY WAVES
REMAINING MAINLY IN THE SRN BRANCH. NEAR SEASONABLE TEMPS INTO THE
WEEKEND WL GIVE WAY TO WARMER WX EARLY NEXT WEEK AND SOME SHOWERS/TS
LATER ON LABOR DAY AS A STRONG COLD FNT APRCHS THE AREA.

WED NGT...SFC HI PRES IN ADVANCE OF SHRTWV RDG WITHIN NRN BRANCH
FLOW WL BRING MOCLR SKIES AND LGT WINDS. SOME HI CLDS MAY BEGIN TO
FILTER INTO THE SW CWA LATE AT NGT AS THE SFC HI SHIFTS TO THE E AND
A BIT OF A RETURN SLY FLOW BEGINS TO DVLP IN ADVANCE OF SHRTWV
EMBEDDED IN WEAKER SRN BRANCH THAT WL BE SHIFTING THRU THE NCENTRAL
PLAINS. EXPECT THE LOWEST MIN TEMPS OVER THE INTERIOR E AND CENTRAL
CLOSER TO THE CORE OF THE HI PRES/PWAT AS LO AS 0.50 INCH OR ABOUT
50 PCT OF NORMAL. PREVIOUS FCST TEMPS APPEAR ON TRACK. MAINTAINED
MENTION OF PATCHY FOG IN THIS AREA.

THU THRU SAT...NOT SURPRISINGLY...MODEL FCST DIFFERENCES BECOME MORE
APRNT REGARDING THE POTENTIAL INTERACTION BTWN THE STRONGER NRN
BRANCH FLOW IN SRN CANADA/WEAKER FLOW OVER THE CONUS AND HOW QUICKLY
AND HOW FAR N PCPN WL SPREAD IN ADVANCE OF A DISTURBANCE RIPPLING
THRU THE SRN BRANCH FM THE NCENTRAL PLAINS TOWARD THE UPR MIDWEST/
GREAT LKS AND WHEN/HOW QUICKLY ANY PCPN WOULD EXIT THE AREA. FOR
INSTANCE...THE 00Z CNDN MODEL WAS MUCH FASTER AT BRINGING PCPN INTO
THE WRN CWA ON THU...BUT THIS MODEL SHOWED MORE PHASING BTWN THE
BRANCHES/A DEEPER SFC LO LIFTING NEWD THRU MN/SSW H85 WINDS UP TO 50
KTS AGGRESSIVELY RETURNING MSTR/HIER INSTABILITY INTO THE UPR LKS.
THIS MODEL THEN SHOWED MORE RAPID DRYING/SUBSIDENCE ON SAT BEHIND
THE STRONGER/MORE PHASED DISTURBANCE. GIVEN THE LACK OF MEANINGFUL
INTERACTION APRNT ON THE SEPARATE FCST H5 FLOWS AND THE SHIFT OF THE
12Z CNDN MODEL TOWARD THE OTHER MORE SUPPRESSED GUIDANCE...WL TEND
TOWARD A CONSENSUS OF THE 12Z GFS AND 00Z ECMWF THAT SHOW A RIBBON
OF HIER QPF OVER MAINLY THE SE CWA ON THE SE EDGE OF FCST CONFLUENCE
ZN IN THE H5 FLOW AND CLOSER TO MORE PERSISTENT SFC LO PRES TROF...
WHERE THE FCST PWAT REMAINS AS HI AS 1.50-2.00 INCHES. ON SAT...A
SHRTWV IN THE NRN BRANCH IS FCST TO SWING THRU NW ONTARIO...WITH
ATTENDANT COLD FNT CROSSING THE UPR LKS. BUT SINCE THE BULK OF THE
MSTR IS LIKELY TO REMAIN TO THE SE CLOSER TO SRN BRANCH DISTURBANCE
TRACK/SFC LO PRES TROF...SUSPECT THE FROPA WL BE RELATIVELY DRY.
HIER POPS WL REMAIN OVER THE SE CWA.

EXTENDED...BEST CHC FOR A DRY DAY APPEARS TO BE ON SUN...WHEN SFC HI
PRES IS FCST TO PASS THRU ONTARIO UNDER A SHRTWV RDG IN THE NRN
BRANCH. BUT SOME OF THE EXTENDED MODELS SHOWED A SLOWER SRN BRANCH
SHRTWV MOVING THRU LOWER MI BRINGING SOME PCPN INTO AT LEAST THE SE
CWA. SO FCST WL SHOW SOME LO CHC POPS OVER MAINLY THAT AREA. ON
LABOR DAY/TUE...STRENGTHENING SSW FLOW BTWN THE HI SHIFTING INTO
QUEBEC AND A FAIRLY STRONG DISTURBANCE/ATTENDANT COLD FNT MOVING
ACRS SRN CANADA WL BRING A RETURN OF WARMER...MOISTER AIR/GREATER
SHOWER AND TS CHCS. WL RELY ON THE MODEL CONSENSUS FOR FCST
PREPARATION.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 122 AM EDT WED AUG 27 2014

MID-LEVEL CLOUDS WILL INCREASE FOR A TIME OVERNIGHT UNTIL AROUND
DAYBREAK ON WEDNESDAY AS A DISTURBANCE CROSSES THE REGION. ALTHOUGH
A FEW SPRINKLES MAY BE POSSIBLE...ESPECIALLY AT IWD...LOW LEVELS
WILL REMAIN DRY ENOUGH SO THAT VFR CONDITIONS WILL PREVAIL. THE MID
CLOUDS ARE EXPECTED TO MOVE OUT BY LATE MORNING INTO THE AFTERNOON
IN THE WAKE OF THE DISTURBANCE.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 352 PM EDT TUE AUG 26 2014

W TO NW WINDS UP TO 25 KTS INTO WED UNDER SHARPER PRES GRADIENT IN
ADVANCE OF SFC HI PRES APPROACHING FROM THE W WILL DIMINISH TO UNDER
20 KTS AS WEAKER PRES GRADIENT DOMINATES THE UPPER GREAT LAKES THRU
THE WEEKEND.
&&

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

$$

SHORT TERM...JLA
LONG TERM...KC
AVIATION...JLB
MARINE...KC






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