Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 302026
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
426 PM EDT TUE SEP 30 2014

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 311 PM EDT TUE SEP 30 2014

12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A SHARP UPR RDG
EXTENDING FM THE MID MS RIVER VALLEY N INTO NW ONTARIO...SUPPORTING
SFC HI PRES JUST N OF LK SUP. ALTHOUGH THE MID TROP IS QUITE DRY...
WITH 12Z H5 DEWPT DEPRESSIONS AS HI AS 45C AT MPX AND QUAD CITIES...
LINGERING LLVL MSTR TO THE S OF THE HI CENTER AND BLO SHARP
SUBSIDENCE INVRN ARND H9-925 CAUSED QUITE A BIT OF LO CLD TO PERSIST
OVER THE UPR LKS THRU THE MRNG. DAYTIME HEATING THAT HAS CAUSED THE
LCL TO RISE THRU THE SLOWLY SINKING INVRN BASE PER FCST SDNGS IS
RESULTING IN STEADY BREAKUP OF THE LO CLD EARLY THIS AFTN. THE LO
CLDS HAVE BEEN MOST RESILIENT OVER THE CENTRAL...WHERE LLVL NE WIND
IS UPSLOPING. LOOKING UPSTREAM...A VIGOROUS NEGATIVELY TILTED SHRTWV
IS LIFTING NNEWD THRU THE NRN PLAINS. DESPITE THE MID LVL DRY AIR IN
PLACE...SOME SHOWERS/TS IN THE RATHER NARROW WARM CONVEYOR BELT
ASSOCIATED WITH THIS DISTURBANCE ARE MOVING INTO SW MN.

MAIN FCST CONCERNS IN THE SHORT TERM ARE FOCUSED ON CLD TRENDS. FCST
CONCERNS ON WED SHIFT TO THE POTENTIAL FOR SOME SHOWERS IN THE
INCRSG SLY FLOW/ISENTROPIC ASCENT TO THE E OF SHRTWV MOVING THRU THE
NRN PLAINS INTO SCENTRAL CANADA.

TNGT...ALTHOUGH THE LO CLDS WL CONTINUE TO DISSIPATE INTO THE EVNG
WITH THE IMPACTS OF DAYTIME HEATING/MIXING...NOCTURNAL COOLING AND
VEERING WINDS TO THE S THAT WL BRING A RETURN OF MOISTER H95-9 AIR
SHOULD RESULT IN MORE LO CLDS. NOT OUT OF THE QUESTION THERE COULD
BE SOME DRIZZLE OVER THE CENTRAL WHERE EXPECTED SSE WIND WL UPSLOPE
OFF LK MI. THE ONE EXCEPTION WL BE OVER THE W...WHERE THE S WIND WL
DOWNSLOPE AND PREVENT/LIMIT THE REFORMATION OF THE LO CLDS. OTRW...
SOME MID/HI CLDS ON THE ERN FLANK OF THE WARM CONVEYOR BELT MSTR
RIBBON MOVING E THRU WL INVADE THE W OVERNGT. THE COMBINATION OF
LINGERING LO CLDS AND/OR INCRSG SLY FLOW WITH H925 WINDS INCRSG UP
TO 20-30 KTS BY 12Z WED WL LIMIT THE DIURNAL TEMP FALL. BUT TEMPS
SHOULD STILL FALL INTO THE 30S AT SOME OF THE INTERIOR COLD SPOTS
THAT SEE MOCLR SKIES FOR A TIME.

WED...ALTHOUGH THE PASSAGE OF SHRTWV/ACCOMPANYING DPVA AND DEEP LYR
QVECTOR CNVGC WELL TO THE W THRU MANITOBA WL LIMIT THE PCPN
POTENTIAL OVER UPR MI...RATHER NARROW WARM CONVEYOR BELT MSTR RIBBON
AND AREA OF H85-5 QVECTOR CNVGC/UPR DVGC AND BAND OF H85-7 FGEN IN
RRQ OF 80KT H3 JET MAX LIFTING NNEWD THRU NW ONTARIO WL BRING THE
THREAT OF SHOWERS TO THE W IN THE AFTN. CONSIDERING THE STRONG
DYNAMIC SUPPORT AND APPRECIABLE DEEP MOISTENING THAT IS FCST TO
RAISE PWAT NEAR 1.5 INCHES /UP TO 200 PCT OF NORMAL/ BY 00Z THU...HI
LIKELY POPS SEEM APPROPRIATE OVER THE FAR W. ALTHOUGH THE MID LVLS
OVER THE E WL REMAIN DRY...FCST SDNGS INDICATE LO CLDS WL PERSIST
MOST OF THE DAY IN THAT AREA AND LIMIT THE DAYTIME TEMP RECOVERY.
BUT WITH STRENGTHENING SLY FLOW BRINGING A RETURN OF H85 TEMPS AS HI
AS 12-13C...MAX TEMPS WL RISE ABV NORMAL...ESPECIALLY IN THE
DOWNSLOPE AREAS NEAR LK SUP.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 425 PM EDT TUE SEP 30 2014

BY 00Z THURSDAY THE AREA WILL BE DOMINATED BY SW FLOW ALOFT...WITH
MOISTURE STREAMING N FROM THE OPEN GULF OF MEXICO. THE INITIAL
SHORTWAVE WILL BE CROSSING THE CWA. WITH STEADY S WINDS AND 850MB
TEMPS NEAR 11C...EXPECT THE FCST LOWS IN THE UPPER 40S TO MID 50S TO
HOLD. WHILE THIS INITIAL BAND OF SHOWERS WILL PRODUCE A QUARTER TO
HALF AN INCH OF LIQUID...THE BEST CHANCE OF WIDESPREAD PRECIP WILL
HOLD OFF UNTIL THURSDAY NIGHT.

THIS WILL BE WHEN THE 500MB LOW SET UP ACROSS MAINLY ONTARIO DIVES
ACROSS MN...AND THE SFC LOW ACROSS MO/IA QUICKLY DEEPENS TO AROUND
998MB ACROSS THE W HALF OF UPPER MI LATE THURSDAY EVENING...AND TO
AROUND 988MB BY DAYBREAK FRIDAY OVER N LAKE SUPERIOR. LOOK FOR WINDS
TO RAPIDLY INCREASE OVER W LAKE SUPERIOR AND FAR W UPPER MI
OVERNIGHT.

THE SFC LOW WILL SHIFT UP ACROSS JAMES BY FRIDAY AFTERNOON AND
EVENING...ALLOWING MUCH COOLER AIR TO SURGE INTO THE REGION. THE GFS
LOOKS TO BE THE STRONGEST WIND WISE BY FRIDAY AFTERNOON...WITH GALE
FORCE GUSTS ACROSS THE KEWEENAW PENINSULA THROUGH THE E HALF OF LAKE
SUPERIOR TO GRAND MARAIS. WHILE THIS MAY BE POSSIBLE...LESS
FAVORABLE WIND DIRECTIONS OFF THE ECMWF AND NAM ARE NOT BACKING THIS
UP QUITE YET. GALES WILL BE STILL BE POSSIBLE SOMETIME THIS
PERIOD...BUT WILL KEEP MORE OF A BLENDED SOLUTION FOR THE TIME BEING
UNTIL MODELS COME MORE IN LINE. WILL KEEP THE TS POTENTIAL IN
THROUGH FRIDAY NIGHT...NO HIGHER THAN SLIGHT CHANCE...AND STILL
MAINLY KEEPING IT OVER UPPER MI/LAKE MI.

THE SFC LOW WILL NOT EXIT FAST...AND WILL KEEP A TROUGH ACROSS THE
UPPER GREAT LAKES THROUGH SUNDAY. THE 500MB LOW WILL SWING ACROSS
UPPER MI FRIDAY NIGHT THROUGH SATURDAY...WITH THE COLDEST AIR OF -23
TO -29C AT 500MB ROTATING ACROSS UPPER MI AND WI. WE ARE BACK TO
THAT TIME OF YEAR WHERE COOL NIGHTS...LOW LEVEL MOISTURE...AND
FAVORABLE UPSLOPE CONDITIONS OFF OF THE WARM LAKES WILL HELP PRODUCE
A FEW SNOW SHOWERS. THIS SHOULD BE THE CASE FRIDAY NIGHT AND AGAIN
SATURDAY NIGHT INLAND FROM THE GREAT LAKES.

THE SFC RIDGE WILL ATTEMPT TO BUILD BACK ACROSS THE UPPER GREAT
LAKES MONDAY INTO MONDAY EVENING. WITH A LESS FAVORABLE WIND
DIRECTION...THIS SHOULD BE THE DRIEST PERIOD DURING THE LONG TERM.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 132 PM EDT TUE SEP 30 2014

DAYTIME HEATING/MIXING WL ALLOW LO CLDS AT SAW AND IWD TO BREAK UP
THIS AFTN WITH A PERIOD OF VFR CONDITIONS INTO AT LEAST THIS EVNG.
ALTHOUGH CMX MAY SEE SOME SC/LOWER CIGS EARLY THIS AFTN ON THE NRN
FRINGE OF SLOWLY DISSIPATING MAIN LO CLD AREA TO THE S...EXPECT VFR
CONDITIONS TO PREDOMINATE THERE INTO AT LEAST THIS EVNG. ONCE HI
PRES IN ONTARIO SHIFTS FARTHER TO THE E TNGT AND A LO PRES TROF
APRCHS FM THE W...THE LLVL WINDS WL SHIFT TO A MORE S DIRECTION. IN
THE PRESENCE OF NOCTURNAL COOLING AND THE RETURN OF MOISTER LLVL
AIR...EXPECT LO CLDS/IFR CONDITIONS TO DVLP AT SAW. DOWNSLOPE NATURE
OF THIS LLVL FLOW MAKES THE FCST AN ESPECIALLY TRICKY ONE FOR CMX
AND IWD...SO INCLUDED JUST A SCT DECK FOR NOW. ANY LO CLDS THAT DVLP
TNGT SHOULD DISSIPATE ON WED AT CMX/IWD WITH DAYTIME HEATING...BUT
THESE CLDS WL BE MORE RESILIENT AT SAW EVEN IF THE CIG HGT DOES LIFT
ABV 1K FT INTO THE MVFR RANGE BY NOON.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 353 PM EDT TUE SEP 30 2014

HIGH PRESSURE OF OVER N ONTARIO WILL MOVE E TO THE CANADIAN
MARITIMES BY WEDNESDAY EVENING. MEANWHILE...LOW PRESSURE OVER
WESTERN NE WILL LIFT ACROSS S MANITOBA WEDNESDAY MORNING...AND
TO HUDSON BAY THURSDAY MORNING. A TROUGH ASSOCIATED WITH THE LOW
WILL MOVE E...REACHING LAKE SUPERIOR ON THURSDAY. A LOW WILL FORM
ALONG THIS TROUGH OVER THE UPPER MS VALLEY THURSDAY EVENING AND THEN
DEEPEN AS IT LIFTS INTO N ONTARIO FRIDAY...AND TO HUDSON BAY FRIDAY
NIGHT. IN ITS WAKE...HIGH PRESSURE OVER THE W PLAINS FRIDAY
AFTERNOON WILL SETTLE OVER THE LOWER MS VALLEY SATURDAY INTO
SUNDAY...AS A TROUGH EXTENDING FROM THE HUDSON BAY LOW LINGERS OVER
N ONTARIO. A PERIOD OF NEAR GALES OUT OF THE W-NW WILL BE POSSIBLE
FROM LATE FRIDAY AFTERNOON THROUGH THE DAY SATURDAY.
&&

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

$$

SHORT TERM...KC
LONG TERM...KF
AVIATION...KC
MARINE...KF






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