Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 140801
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
401 AM EDT SUN SEP 14 2014

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 409 PM EDT SAT SEP 13 2014

WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW THE VIGOROUS SHORTWAVE
THAT PRODUCED PCPN OVER MUCH OF UPPER MI LAST NIGHT NOW MOVING THRU
SRN ONTARIO INTO QUEBEC. UPSTREAM...A PAIR OF SHORTWAVES ARE
NOTED...ONE OVER ND/SRN MANITOBA AND THE OTHER OVER SRN
SASKATCHEWAN. THESE WAVES WILL BRING THE NEXT PCPN CHC TO UPPER MI
ON SUNDAY. IN THE WAKE OF LAST NIGHTS SYSTEM...850MB TEMPS ARE
CURRENTLY -1 TO -2C OVER LAKE SUPERIOR. TYPICALLY AT THIS TIME OF
YEAR...THIS WOULD BE MORE THAN SUFFICIENT FOR LAKE EFFECT CLOUDS AND
PCPN. HOWEVER...WITH A LARGE PORTION OF LAKE SUPERIOR HAVING SFC
WATER TEMPS PROBABLY ONLY AROUND 7-9C...THERE WAS NOT MUCH IN THE
WAY OF LAKE EFFECT CLOUDS EARLIER TODAY. IN FACT...THE LAKE HAS
BEHAVED MOSTLY AS STABILIZING INFLUENCE. ONE BAND WITH A FEW
SPRINKLES DID STREAM INTO ERN MARQUETTE COUNTY BRIEFLY THIS MORNING
DUE TO LAND BREEZE CONVERGENCE AND WARMER WATER TO THE S AND E OF
THE KEWEENAW. THIS AFTN...DAYTIME HEATING/LOW-LEVEL CONVERGENCE AND
MOISTURE FROM THE LAKE RESULTED IN ADDITIONAL SPRINKLES DEVELOPING
IN ERN MARQUETTE COUNTY. THESE SPRINKLES ARE DRIFTING SE THRU DELTA
AND WRN ALGER COUNTIES. WHILE LAKE EFFECT CLOUDS WERE AT A MINIMUM
EARLIER TODAY...850MB THERMAL TROF COMBINED WITH ADDED MOISTURE FROM
THE LAKE RESULTED IN WIDESPREAD CU/STRATOCU DEVELOPING OVER THE LAND
ONCE DAYTIME HEATING BEGAN.

TONIGHT...MAIN FCST CONCERN IS FROST POTENTIAL. WHILE CU/STRATOCU IS
STILL QUITE EXTENSIVE...THE DIURNAL NATURE OF THE CLOUD DEVELOPMENT
SUGGESTS THE CLOUDS WILL DISSIPATE THIS EVENING WITH THE LOSS OF
DAYTIME HEATING. MEANWHILE...LEAD SHORTWAVE TO THE W IS GENERATING A
FAIR AMOUNT OF HIGH CLOUDINESS WHICH WILL STREAM OVER THE FCST AREA
AS THE WAVE MOVES OVER THE UPPER LAKES. DISSIPATING STRATOCU THIS
EVENING BEING REPLACED BY HIGH CLOUDS WILL BE ONE FACTOR HELPING TO
KEEP TEMPS FROM CRASHING. OTHER FACTOR WILL BE DEPARTURE OF HIGH
PRES RIDGE CURRENTLY OVER THE AREA. AS PRES GRADIENT TIGHTENS BTWN
THE EXITING HIGH AND APPROACHING SFC TROF... THERE WILL BE SOME
INCREASE IN MIXING. THAT SAID...THE INITIAL DRY AIR MASS
(PRECIPITABLE WATER 45-55PCT OF NORMAL) AND LIGHT WINDS OVER THE
AREA WILL STILL ALLOW TEMPS TO FALL INTO THE MID 30S AND TO EVEN THE
LOWER 30S IN TRADITIONAL COLD SPOTS. SO...FCST WILL SHOW PATCHY
FROST OVER MUCH OF THE INTERIOR. AT THIS POINT...NOT EXPECTING
COVERAGE TO BE LARGE ENOUGH TO WARRANT A FROST ADVY. EVENING SHIFT
WILL NEED TO MONITOR CLOUD TRENDS AND TEMPS TO RE-EXAMINE THE NEED
FOR HEADLINE ISSUANCE BY LATE EVENING.

ON SUN...SECOND SHORTWAVE WILL SWING ACROSS THE UPPER GREAT LAKES.
AS IN PREVIOUS DAYS...MODELS CONTINUE TO INDICATE BEST
MOISTURE/FORCING PASSING JUST N OF THE AREA...ALONG AND N OF
PROJECTED VORT TRACK. SEE NO REASON TO DEVIATE MUCH FROM PREVIOUS
FCST WITH MAINLY CHC POPS SPREADING INTO WRN UPPER MI IN THE MID TO
LATE MORNING AND THEN REACHING THE E MID TO LATE AFTN. EXPECT HIGH
TEMPS GENERALLY IN THE UPPER 50S TO LWR 60S.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 401 AM EDT SUN SEP 14 2014

FOR MON...A SHORTWAVE LOOKS TO MOVE INTO THE UPPER TROUGH POSITIONED
OVER THE GREAT LAKES REGION...BUT THE SHORTWAVE WILL BE BEHIND A SFC
COLD FRONT THAT WILL MOVE THROUGH ABOUT 12 HOURS AHEAD ON SUN NIGHT.
GIVEN THAT THE BEST MOISTURE WILL BE ALONG AND AHEAD OF THE FRONT AS
A 1022MB SFC HIGH OVER THE PLAINS NOSES INTO THE REGION BEHIND THE
FRONT...WIDESPREAD PRECIP IS NOT EXPECTED ON MON. COULD SEE
SCATTERED SHOWERS AS THE SHORTWAVE PASSES OR RIGHT BEHIND THE
SHORTWAVE AS THE 850MB THERMAL TROUGH PASSES...WHICH MAY PROVIDE
SOME ADDITIONAL WEAK INSTABILITY. HIGH TEMPS WILL BE IN THE 50S.

THE UPPER TROUGH INTENSIFIES AND MOVES SLOWLY E THROUGH MID WEEK AS
THE UPPER RIDGE OVER THE WRN CONUS MOVES OVER THE ROCKIES. UPPER
LEVEL ENERGY TUE THROUGH THU WILL BE MAINLY N/NE OF THE CWA...BUT
SOME LOWER LEVEL FEATURES MAY LEAD TO SOME RAIN. MODELS GENERALLY
AGREE THAT A WEAK COLD FRONT WILL MOVE IN FROM THE N/NNE TUE NIGHT
AND THEN STALL OVER THE AREA WHILE DIMINISHING WED INTO THU. BEST
CHANCES FOR PRECIP DURING THIS TIME IS TUE NIGHT INTO WED SINCE A
SFC HIGH MOVES JUST N/NE OF THE CWA WED NIGHT INTO THU...RESULTING
IN A DRIER AIRMASS. ADDITIONALLY...THERE IS POTENTIAL FOR FRONT MON
NIGHT AND WED NIGHT.

THE PATTERN BECOMES MORE PROGRESSIVE FRI INTO SAT...WHICH MAY LEAD
TO A LOW PRESSURE SYSTEM OR JUST A TROUGH MOVING IN FROM THE W ON
SAT. THERE IS DISAGREEMENT BETWEEN MODELS FOR FRI AND SAT...WHICH IS
TO BE EXPECTED GIVEN THE MORE PROGRESSIVE/TRANSITIONAL FLOW. GENERAL
CONSENSUS DOES SHOW WAA FRI INTO EARLY SAT...BRINGING A WARMER
AIRMASS WITH 850MB TEMPS OF 13C-15C. PRECIP WILL BE POSSIBLE DURING
THIS TIME GIVEN THE WAA...POSSIBLE SHORTWAVE ENERGY HINTED AT BY
MODELS...AND THE ARRIVAL OF A SFC LOW OR TROUGH. DEPENDING ON AMOUNT
OF CLEARING...MAY SEE TEMPS TOP OUT IN THE 70S IN SPOTS BOTH
DAYS...BUT WILL LEAN MORE TOWARD COOLER CONSENSUS GUIDANCE GIVEN THE
CHANCES FOR PRECIP/CLOUD COVER...WHICH HAS HIGHS IN THE MID 60S TO
70.
&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 715 PM EDT SAT SEP 13 2014

UNDER RELATIVELY DRY LOW LEVELS...VFR CONDITIONS WILL PREVAIL THRU
THE FCST PERIOD AT KIWD/KCMX/KSAW. ON SUN...AN APPROACHING LOW PRES
TROF SHOULD BRING SCT -SHRA INTO NW UPPER MI BY AFTN. HAVE INCLUDED
A VCSH MENTION AT KCMX.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 409 PM EDT SAT SEP 13 2014

APPROACHING LOW PRES TROF WILL RESULT IN INCREASING S TO SW WINDS
TONIGHT INTO SUN. WHILE LOWER OBS PLATFORMS SHOULDN`T SEE WINDS
GREATER THAN THE 10-20KT RANGE...HIGH OBS PLATFORMS WILL PROBABLY
SEE GUSTS TO AROUND 25KT. WINDS SHOULD FALL BACK TO MOSTLY 10-20KT
SUN NIGHT THRU MON. THERE MAY BE SOMEWHAT HIGHER WINDS AGAIN LATE
MON NIGHT THRU EARLY WED AHEAD OF AND BEHIND A COLD FRONT THAT WILL
DROP S ACROSS LAKE SUPERIOR TUE. LIGHTER WINDS WILL THEN BE THE RULE
LATER WED THRU THU HAS HIGH PRES MOVE SE ACROSS NRN ONTARIO TOWARD
THE LOWER LAKES.
&&

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

$$

SHORT TERM...ROLFSON
LONG TERM...TITUS
AVIATION...07
MARINE...ROLFSON






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