Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 300836
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
436 AM EDT TUE SEP 30 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 247 PM EDT MON SEP 29 2014

UPPER AIR PATTERN CONSISTS OF A CLOSED 500 MB LOW OVER THE CENTRAL
ROCKIES WITH AN ASSOCIATED TROUGH...A TROUGH OVER THE UPPER GREAT
LAKES AND A RIDGE OVER THE PLAINS. THE TROUGH OVER THE UPPER GREAT
LAKES MOVES SOUTHEAST TODAY AND THE RIDGE IS POISED TO BUILD INTO
THE AREA ON TUE.

GOING FORECAST HAS THINGS PRETTY WELL IN HAND. LOOKS LIKE LOW LEVEL
MOISTURE AND UPSLOPE FLOW WILL LINGER NEAR LAKE SUPERIOR AND HUNG
ONTO DRIZZLE RATHER THAN SHOWERS AS RAIN BAND CONTINUES TO MOVE OUT.
TEMPERATURES WILL NOT REALLY GO ANYWHERE TONIGHT AND WILL CONTINUE A
SLOW FALL WHICH WAS ALREADY COVERED IN THE FORECAST. DID HANG ONTO
CLOUDS LONGER TONIGHT AND ALSO FOR TUE AS SATELLITE SHOWS A LOT OF
CLOUDS TO STILL GO THROUGH TONIGHT AND 850 MB TEMPERATURES DROPPING
DOWN TO 2C BEFORE WARMING LATE TONIGHT. WITH LAKE SUPERIOR
TEMPERATURES RANGING FROM 7C TO 10C...THIS IS BORDERLINE FOR LAKE
ENHANCED PCPN...BUT ENOUGH FOR LAKE EFFECT CLOUDS COVER AND SOME
UPSLOPE DRIZZLE POSSIBLE WITH BORDERLINE LAKE-850MB DELTA-T. WILL
ALSO HANG ONTO AREAS OF UPSLOPE FOG FOR TONIGHT AS WELL AND HAVE
THIS INTO TUE MORNING.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 433 AM EDT TUE SEP 30 2014

ATTENTION IN THE LONG TERM WILL BE ON THE UPPER TROUGH THAT WILL
MOVE FROM THE INTERMOUNTAIN WEST AT 12Z WED INTO THE CWA AT 00Z SAT
WHILE DEEPENING AND BECOMING NEGATIVELY TILTED...AS IS GENERALLY
AGREED ON BY NWP. THE UPPER TROUGH THEN LOOKS TO CLOSE OFF INTO A
LOW AS IT MOVES THROUGH THE REGION FRI NIGHT...BUT MODEL
DISAGREEMENT INCREASES SIGNIFICANTLY AT THIS POINT WITH THE STRENGTH
AND TRACK OF THE SYSTEM. GENERAL MODEL AGREEMENT DOES INCREASE SUN
NIGHT INTO MON WITH MODELS SHOWING A DEEP TROUGH OVER THE ERN CONUS.
ONE THING THAT CAN BE SAID WITH CERTAINTY IS THAT THE PATTERN WILL
BE MORE ACTIVE THAN LAST WEEK.

SHOWERS /POSSIBLY WITH SOME THUNDER/ IS STILL EXPECTED TO VERY
GRADUALLY MOVE W TO E ACROSS THE CWA WED THROUGH THU DUE TO
WAA/ISENTROPIC ASCENT AHEAD OF A SFC TROUGH/COLD FRONT. MAIN ISSUE
TO POINT OUT FROM A CONFIDENCE STANDPOINT IS THAT SHORTWAVE ENERGY
WILL PROBABLY EJECT FROM THE UPPER TROUGH TO THE W /AS SHOWN BY
NWP/...BUT THE MODELS DO NO AGREE ON THE STRENGTH/TIMING/TRACK OF
ANY ENERGY AND ASSOCIATED SFC CYCLOGENESIS. THERE WILL PROBABLY BE
PERIODS OF HEAVIER PRECIP AND/OR GREATER PRECIP COVERAGE...BUT
ACCURATELY TIMING THOSE OUT IS NOT POSSIBLE AT THIS TIME. HIGH TEMPS
IN THE 60S LOOK TO MAKE A RETURN ON WED AND THU DUE TO THE WAA AND
RESULTING WARM AIRMASS /850MB TEMPS OF 10-13C/.

AS PREVIOUSLY MENTIONED...THE UPPER TROUGH TEARS INTO THE AREA THU
NIGHT AND FRI...BRINGING A MUCH COLDER AIRMASS WITH IT. AT LEAST
PORTIONS OF THE CWA SHOULD SEE 850MB TEMPS BELOW 0C BY THE END OF
THE DAY FRI. GIVEN THE STRENGTH OF THE TROUGH AND MAGNITUDE OF
RESULTING HEIGHT FALLS AS IT MOVES IN...PERIODS OF PRECIP DOES LOOK
LIKE A GOOD BET THU NIGHT INTO FRI...ALTHOUGH AMOUNTS WILL BE
DEPENDENT ON THE HIGHLY UNCERTAIN SFC LOW LEVEL FEATURES. SOME
MODELS /MAINLY THE GFS AND NAM/ SHOW A DEEPER SFC LOW TRANSITING THE
CWA THU NIGHT INTO FRI /AS THE GFS HAS SHOWN VARIOUS ITERATIONS OF
FOR THE LAST SEVERAL RUNS/. IF THIS DOES OCCUR...GALES WOULD LIKELY
OCCUR ACROSS PORTIONS OF THE GREAT LAKES...ALONG WITH MORE
SUBSTANTIAL RAINFALL AMOUNTS. WHILE THIS IS NOT OUT OF THE
QUESTION...THERE IS JUST TOO MUCH UNCERTAINTY AT THIS POINT TO ADD
THIS SCENARIO TO THE FORECAST. PRECIP FRI NIGHT INTO SAT IS A BIT
MORE CERTAIN SINCE IT WILL BE LESS DUE TO A SYNOPTIC SYSTEM AND MORE
TO SUB ZERO 850MB TEMPS AND WNW-NW LOW LEVEL WINDS LEADING TO LAKE
EFFECT PRECIP NEAR LAKE SUPERIOR. IN FACT...DEPENDING ON EXACTLY HOW
COLD THE AIRMASS IS...SNOW IS CERTAINLY NOT OUT OF THE PICTURE FRI
NIGHT INTO SAT NIGHT...BUT ACCUMULATING SNOW IS UNLIKELY /ESPECIALLY
SIGNIFICANT ACCUMULATIONS/. DID ADD SNOW CHANCES TO THE FORECAST
OVER HIGHER TERRAIN OF WRN UPPER MI FRI NIGHT INTO EARLY SAT AND FOR
PORTIONS OF NWRN AND NERN UPPER MI SAT NIGHT. HIGH TEMPS BY SATURDAY
LOOK TO BE IN THE UPPER 40S TO LOW 50S....WITH LOW TEMPS SAT NIGHT
FROM THE UPPER 20S TO MID 30S.

GOING COMPLETELY WITH MODEL CONSENSUS IDEA SUN AND MON GIVEN
UNCERTAINTY.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 133 AM EDT TUE SEP 30 2014

CONSIDERABLE LOW-LEVEL MOISTURE WILL LINGER OVERNIGHT WITH CIGS NEAR
IFR/MVFR THRESHOLD AT KIWD/KCMX/KSAW. HOWEVER...SOME DRYING WILL PUSH
INTO UPPER MI...AND THIS SHOULD RESULT IN CIGS CLIMBING TO AT OR
ABOVE 2K FT THIS MORNING. DAYTIME MIXING AND ADDITIONAL DRY ADVECTION
WILL RESULT IN ENOUGH CLEARING FOR VFR CONDITIONS AT KCMX BY LATE
MORNING...AT IWD BY AFTN AND AT KSAW BY LATE AFTN WHERE MORE
PERSISTENT UPSLOPE FLOW PREVAILS.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 247 PM EDT MON SEP 29 2014

IN THE WAKE OF A SHARP COLD FRONT...N TO NE WINDS WILL SLOWLY
DIMINISH FROM BELOW 20KT TONIGHT AS HIGH PRESSURE OVER NRN ONTARIO
MOVES CLOSER. WINDS UNDER 20KT WILL BE THE RULE TUE THRU THU NIGHT.
FRI INTO SAT...COLDER AIR SWEEPING INTO THE UPPER LAKES BEHIND A
COLD FRONT AND LOW PRES SYSTEM WILL LEAD TO STRENGTHENING NW WINDS
AND POTENTIALLY GALES.
&&

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

$$

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






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