Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 290936
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
536 AM EDT MON SEP 29 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 535 AM EDT MON SEP 29 2014

WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A SHORTWAVE TROF DROPPING
SE ACROSS NRN ONTARIO AND NRN MN. AT THE SFC...ASSOCIATED SHARP COLD
FRONT EXTENDS FROM SCNTRL MN THRU WI AND THEN ACROSS SCNTRL AND ERN
UPPER MI. IT APPEARS A WEAK SFC WAVE MAY BE LOCATED ALONG THE TROF
IN UPPER MI. AS EXPECTED...NEARLY ALL PCPN IS OCCURRING ON THE COLD
SIDE OF THE SFC FRONTAL BOUNDARY WHERE A NICE RIBBON OF LOW-MID
LEVEL FRONTOGENESIS FORCING IS LOCATED UNDERNEATH RIGHT ENTRANCE OF
UPPER JET.

INHERITED FCST HAD A GOOD HANDLE ON THE SITUATION TODAY.
WELL-DEFINED UPPER JET STREAK BEGINS TO LOSE DEFINITION TODAY.
THUS...UPPER JET FORCING AND CORRESPONDING LOW-MID LEVEL
FRONTOGENESIS ALSO BEGIN TO WEAKEN. SHOULDN`T HAVE AN IMMEDIATE
IMPACT ON BAND OF PCPN PUSHING ACROSS THE AREA...BUT THERE MAY BE
SOME TENDENCY FOR PCPN TO BECOME A LITTLE LESS ORGANIZED AND LIGHTER
WITH TIME AS THE PCPN MOVES ACROSS THE SRN FCST AREA. OVERALL...
MINOR CHANGES WERE MADE TO PCPN TIMING THIS MORNING TO ACCOUNT FOR
RADAR TRENDS OVER THE LAST SEVERAL HOURS. BIGGER CHANGE WAS TO
DIMINISH POPS MORE SIGNIFICANTLY FROM W TO E DURING THE DAY AS
FAIRLY IMPRESSIVE DEEP LAYER QVECTOR DIVERGENCE/SUBSIDENCE ARRIVES.
CYCLONIC FLOW/ABUNDANT LOW-LEVEL MOISTURE AND LAKE-850MB DELTA T
NEARING THE MARGINAL THRESHOLD FOR LAKE EFFECT PCPN SHOULD WORK TO
HOLD IN SOME -RA/-SHRA NEAR LAKE SUPERIOR...ESPECIALLY NCNTRL UPPER
MI WHERE UPSLOPE FLOW WILL BE BEST. WITH CAA AND CLOUD COVER LIKELY
HOLDING TOUGH THRU THE DAY...TEMPS WILL REMAIN NEARLY STEADY IN THE
40S ACROSS THE W AND NCNTRL AND SHOULD SLOWLY FALL FOR MUCH OF THE
DAY ELSEWHERE.

ANY LINGERING PCPN (-SHRA/-DZ) MAINLY NEAR LAKE SUPERIOR WILL END
TONIGHT AS GRADUALLY DRIER AIR FILTERS INTO THE AREA AND AS
LOW-LEVEL AIR MASS MODERATES...ENDING ANY LAKE COMPONENT TO PCPN.
TEMPS POSE A CHALLENGE AS CLOUD COVER WILL DICTATE HOW LOW TEMPS
FALL. AT THIS POINT...IT APPEARS QUITE A BIT OF LOW CLOUDINESS WILL
LINGER TONIGHT. BEST CHC FOR SOME PARTIAL CLEARING...PROBABLY LATE
IN THE NIGHT...WILL BE OVER THE W WHERE LOW-LEVEL FLOW BECOMES
ANTICYCLONIC OVERNIGHT. TEMPS IN THAT AREA MAY FALL TOWARD
FREEZING.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 426 AM EDT MON SEP 29 2014

FIRST 24 HOURS OF THE FORECAST STARTING 12Z TUE LOOKS PRETTY QUIET
AS A SHARP UPPER RIDGE AND SFC RIDGE PASS THROUGH THE CWA. THE
AIRMASS WARMS A BIT ON TUE AS THE UPPER RIDGE MOVES IN...WITH 850MB
TEMPS INCREASING FROM 7-11C AT 12Z TUE TO 8-14C AT 00Z WED. WILL NOT
SEE FULL SFC WARMING POTENTIAL OF THE AIRMASS DUE TO A CLOUDY START
TO THE DAY AND SLOW CLEARING...BUT HIGH TEMPS LOOK TO MAINLY BE IN
THE 50S.

W OF THE UPPER RIDGE TRANSITING THE REGION IS A AN AMPLIFIED UPPER
TROUGH COVERING THE WRN HALF OF THE CONUS WITH EMBEDDED SHORTWAVES.
WHILE THE UPPER TROUGH IS SLOW TO MOVE E...SOUTHERLY FLOW WILL LEAD
TO WAA/ISENTROPIC ASCENT MOVING IN TUE NIGHT AHEAD OF A COLD FRONT
SET TO MOVES ACROSS THE AREA ON THU. THIS LEADS TO RAIN MOVING
ACROSS THE WRN HALF OF THE CWA FRI MORNING THROUGH FRIDAY
EVENING...EVENTUALLY COVERING THE ERN CWA ON THU. THE RAIN MAY HAVE
SOME ADDITIONAL FORCING FROM SHORTWAVE ENERGY EJECTING OUT OF THE
UPPER TROUGH...BUT THAT IS FAR FROM CERTAIN. EVEN SO...MODEL
AGREEMENT DOES ALLOW FOR ENOUGH CONFIDENCE TO HAVE LIKELY POPS
REMAINING IN THE FORECAST FOR THIS TIME PERIOD. THE 8-14C 850MB
TEMPS WILL REMAIN THROUGH WED...ALLOWING MAX TEMPS TO BE IN THE 60S.
HIGH FOR THU WILL BE SIMILAR SINCE THE FRONT MOVES THROUGH LATER IN
THE DAY AND IS RELATIVELY WEAK.

REAL SIGNIFICANT PORTION OF THE LONG TERM IS LATE IN THE WEEK INTO
THE WEEKEND AS THE UPPER TROUGH OVER THE WRN CONUS GETS REINFORCED
BY ENERGY MOVING OUT OF CANADA. THE TROUGH SHARPENS UP AND MOVES
INTO THE CWA LATE THU NIGHT INTO SAT...BEFORE MOVING E BY SUN. WHILE
MODELS DO AGREE WELL ON THE OVERALL UPPER PATTERN...THERE ARE MANY
UNCERTAINTIES ON A SMALLER SCALE WITH EMBEDDED ENERGY AND
CYCLOGENESIS/SFC FEATURE DEVELOPMENT. CAN SAY WITH GOOD CERTAINTY
THAT IT WILL BE COLDER AS 850MB TEMPS FALL TO BELOW 2C BY FRI
EVENING AND AS LOW AS -5C ON SAT. TEMPS WILL LIKELY NOT RISE ABOVE
50 DEGREES IN SOME SPOTS ON SAT...WITH THE WARMER LOCATIONS JUST
BARELY GETTING ABOVE 50 DEGREES. WIDESPREAD PRECIP IS UNCERTAIN DUE
TO MODEL DISAGREEMENT WITH UPPER LEVEL ENERGY AND ASSOCIATED LOW
LEVEL FEATURES...BUT LAKE EFFECT RAIN /AND MAYBE SOME SNOW
FLAKES...BUT NO ACCUMULATING SNOW/ NEAR LAKE SUPERIOR IS MORE
CERTAIN JUST DUE TO THE COLD AIRMASS AND N TO NW LOW LEVEL WINDS.

SUN DOES LOOK DRIER AND WARMER...BUT CAN NOT RULE OUT OF LIGHT
PRECIP.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 126 AM EDT MON SEP 29 2014

LIFR AT KCMX AND KIWD HAS SPREAD INTO KSAW AS A COLD FRONT DROPS ACROSS
THE AREA WITH ABUNDANT LOW LEVEL MOISTURE AND LIGHT RAIN IN ITS WAKE.
SOME IMPROVEMENT IS EXPECTED AT KCMX THIS AFTN AS THE NE WIND WILL BE
LESS FAVORABLE FOR UPSLOPE FLOW...BUT KIWD AND KSAW ARE NOT EXPECTED
TO SEE MUCH IMPROVEMENT UNTIL LATE THIS AFTERNOON. MVFR CONDITIONS
ARE THEN EXPECTED BY EVENING.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 535 AM EDT MON SEP 29 2014

IN THE WAKE OF A SHARP COLD FRONT PASSING THRU THE UPPER GREAT
LAKES...N TO NE WINDS HAVE INCREASED TO 20-30KT OVER MUCH OF LAKE
SUPERIOR DURING THE NIGHT. WINDS SHOULD REMAIN IN THAT RANGE TODAY...
BUT THERE WILL BE SOME DIMINISHING OF WINDS OVER WRN LAKE SUPERIOR
THIS AFTN AS PRES GRADIENT WEAKENS WITH COLD FRONT MOVING FARTHER
FROM THE AREA. DURING THE MORNING...THERE MAY BE A FEW GALE FORCE
GUSTS OVER NCNTRL LAKE SUPERIOR. WINDS WILL DIMINISH FROM W TO E
TONIGHT AS HIGH PRES OVER NRN ONTARIO MOVES CLOSER. WINDS UNDER 20KT
WILL BE THE RULE TUE THRU THU. HOWEVER...AS PRES GRADIENT TIGHTENS
SOME ON WED BTWN DEPARTING HIGH PRES AND AN APPROACHING COLD
FRONT...SOUTHERLY WINDS MAY BE A LITTLE STRONGER ON WED...MAINLY
OVER ERN LAKE SUPERIOR. 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...ROLFSON
LONG TERM...TITUS
AVIATION...JLB
MARINE...ROLFSON





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