Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 241133
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
633 AM EST TUE FEB 24 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 504 AM EST TUE FEB 24 2015

WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL FLOW FROM N
CNTRL CANADA INTO THE WRN LAKES BETWEEN A TROUGH OVER HUDSON BAY AND
A RIDGE FROM THE ERN PACIFIC INTO THE NW CONUS. WAA AND ISENTROPIC
LIFT AHEAD OF A SHORTWAVE TROUGH FROM NW ONTARIO INTO FAR NRN MN
SUPPORTED LIGHT SNOW ACROSS UPPER MICHIGAN WITH VSBY GENERALLY IN
THE 1-3SM RANGE. ANOTHER COMPACT UPSTREAM SHRTWV OR PV ANOMALY WAS
LOCATED OVER NRN MANITOBA. AT THE SFC...GUSTY SOUTHWEST WINDS AHEAD
OF TROUGH FROM NW ONTARIO INTO ERN MN WERE GRADUALLY DIMINISHING
EARLY THIS MORNING.

TODAY...EXPECT THAT THE WAA/ISENTROPIC LIFT WILL PRODUCE SNOW
AMOUNTS OF AN INCH OR TWO...GREATEST FROM THE KEWEENAW INTO THE ERN
CWA...IN LINE WITH THE STRONGEST LIFT. SNOW MAY ALSO INCREASE THIS
MORNING OVER THE WEST AS THE TROUGH AND SHRTWV MOVE THROUGH WITH A
PERIOD OF ENHANCED LOW LEVEL CONV. ALTHOUGH THE WRN LAKE IS MOSTLY
FROZEN THERE MAY BE ENOUGH GAPS IN THE ICE COVER FOR SOME ADDITIONAL
HEAT/MOISTURE TO BOOST THE SNOW. 230 SW FLOW OFF OF NRN LAKE
MICHIGAN WILL KEEP ADDITIONAL LES MAINLY E OF THE CWA. BY THIS
AFTERNON...THE NRN MANITOBA SHRTWV COULD SUPPORT A PERIOD OF HEAVIER
SNOW INTO CNTRL UPPER MI FOR A FEW HOURS GIVEN THE FORCING WITH THIS
FEATURE AND STEEP SFC-700 MB LAPSE RATES AS A -30C 700 MB COLD POOL
MOVES THROUGH. THIS COULD PRODUCE LOCAL ACCUMULATIONS OF AN INCH OR
TWO.

TONIGHT...ANOTHER BATCH OF COLD AIR WILL FOLLOW THE SHRTWV AS WINDS
VEER TO THE NW AND CAA DROPS 850 MB TEMPS INTO THE -23C TO -27C
RANGE. THE EXTENSIVE ICE COVER WILL SIGNFICANTLY REDUCE ANY LES
POTENTIAL BUT WITH THE RECENT STRONG WINDS A FEW MORE GAPS COULD
ALLOW SOME BANDS TO DEVELOP WITH LIGHT ACCUMULATIONS OF AN INCH OR
LESS...ESPECIALLY WITH THE LONGER FETCH INTO THE ERN CWA. ALTHOUGH
SOME LINGERING CLOUD COVER WILL LIMIT TEMP FALL...EXPECT MIN TEMPS
DOWN TO -7F TO -14F WITH WIND CHILL VALUES TO NEAR ADVISORY LEVELS
OF -25. HOWEVER...WINDS ARE ALSO EXPECTED TO DIMINISH TO NEAR 5 MPH
IN THE COLDEST AREAS.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 446 AM EST TUE FEB 24 2015

WITH AN OVERALL DIMINISHING TREND IN THE LES...WITH THE
MOVING/BREAKING ICE HAVING A SIGNIFICANT IMPACT ON WHAT WE AREA ABLE
TO GET IN OUR NW TO W FLOW THAT WILL REMAIN THROUGH FRIDAY. EXPECT A
FEW STREAMERS OF LES OFF OPEN AREAS...IMPACTING PRIMARILY ALGER AND
N LUCE COUNTIES.

THE MAIN STORY FOR THIS PERIOD WILL BE LOW TEMPS AND THE POTENTIAL
FOR NEAR ADVISORY WIND CHILLS AGAIN. INCLUDED IN THE HWO THE MENTION
OF WIND CHILL READINGS OF 20 BELOW TO NEAR 30 BELOW ZERO THROUGH MID
MORNING WEDNESDAY...AND AGAIN WEDNESDAY NIGHT INTO THURSDAY MORNING.
THE TIME OF NEAR CRITICAL WIND CHILL VALUES WILL LIKELY BE SHORTER
THURSDAY NIGHT INTO EARLY FRIDAY MORNING. MAY NOT HOIST WIND CHILL
ADVISORIES FOR THESE PERIODS OVER THE ENTIRE CWA AS WINDS MAY NOT
GET TO THE 10MPH OR GREATER THRESHOLD. GENERALLY WE HAVE BEEN TOO
STRINGENT ON THE WIND SIDE OF THE CRITERIA WHEN WIND CHILLS HAVE
BEEN GETTING CLOSER TO WARNING LEVELS.

KEPT WITH VERY COLD AIR SETTLING IN WEDNESDAY NIGHT/THURSDAY
MORNING...WITH THE TRADITIONAL COLD SPOTS FALLING -20 TO -25F. THE
LONGWAVE TROUGH IS BASICALLY OVERHEAD...AND 850MB TEMPS -23 TO
-25C...AND THE SFC RIDGE EXPANDING ACROSS THE UPPER GREAT LAKES FROM
CENTRAL CANADA AND THE N PLAINS STATES.

OFFSHORE WINDS FRIDAY THROUGH SATURDAY SHOULD RESULT IN DRY WEATHER
FOR ALL OF UPPER MI. OPTED FOR A MODEL BLEND FOR SATURDAY NIGHT
THROUGH THE REST OF THE PERIOD...ONCE AGAIN LIMITED THE LES
POTENTIAL TO CHANCE AT MOST GIVEN THE ICE COVER OVER MUCH OF LAKE
SUPERIOR. THE SNOW POTENTIAL IS BECOMING LESS IMPRESSIVE
SUNDAY...WITH MUCH OF THE MOISTURE UNABLE TO RISE MUCH FARTHER N
THAN S WI.

AS NOTED FROM PREVIOUS LONG TERM DISCUSSION... FEBRUARY 2015 IS A
LOCK TO BREAK LAST YEAR/S RECORD COLD FEBRUARY. THROUGH THE
22ND...THE AVERAGE TEMP THIS MONTH HAS BEEN 2.9 DEGREES. PERFORMING
A ROUGH CALCULATION BASED OFF THE FORECAST DATA...WE SHOULD END UP
RIGHT AROUND 2.5 DEGREES FOR THE AVERAGE TEMPERATURE THIS MONTH AT
NWS MARQUETTE. THAT WOULD BEAT THE RECORD OF 5.6 DEGREES SET JUST
LAST YEAR. AT OTHER SITES WITH LONGER PERIODS OF RECORD...THIS
FEBRUARY WILL LIKELY END UP AS A TOP 5 OR TOP 10 COLDEST FEBRUARY.
MANY SITES HAVE 1936 AS THE COLDEST FEBRUARY ON RECORD...WHICH AT
IRONWOOD EVEN ENDED UP WITH AN AVERAGE TEMPERATURE BELOW ZERO
(ALMOST 4 DEGREES COLDER THAN WHAT HAS OCCURRED THIS MONTH).
&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 630 AM EST TUE FEB 24 2015

AN AREA OF -SN IN ADVANCE OF AN APPROACHING COLD FRONT WILL
BRING A PERIOD OF MVFR CONDIITONS FOR SAW/IWD AND IFR AT CMX.
THE PERSISTENT IFR VSBYS WITH FALLING -SN AND SOME BLSN WHIPPED UP
BY GUSTY SW WINDS AT CMX WILL IS DUE TO THE CLOSER TRACK OF THE
ASSOCIATED SHRTWV AND DEEPER MOISTURE. ALTHOUGH THERE MAY BE SOME
IMPROVEMENT IMMEDIATELY FOLLOWING THE FRONTAL PASSAGE AND STRONGER
DYNAMIC FORCING THIS MORNING...A REINFORCING DISTURBANCE AND
ATTENDANT ARCTIC COLD FRONT WILL BRING MORE SHSN/GUSTY NW WINDS/BLSN
IN THE AFTERNOON IN THE PRESENCE OF DIURNAL HEATING AND CAA THAT
SHARPEN LOW LEVEL LAPSE RATES. ALTHOUGH EXTENSIVE ICE COVER WILL
LIMIT THE INTENSITY OF THE LES...THE BLSN AT THE MORE EXPOSED CMX
LOCATION WILL LIKELY RESULT IN IFR VSBYS AT LEAST PART OF THE TIME
UNTIL THE EVNG...WHEN LARGER SCALE STRONG SUBSIDENCE IN THE WAKE OF
THIS DISTURBANCE SUPPRESSES THE LES OVER THE ENTIRE AREA.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 504 AM EST TUE FEB 24 2015

SOUTHWEST GALES AROUND 35 KTS WILL DIMINISH EARLY THIS MORNING AS A
TROUGH MOVES INTO THE AREA. A COLD FRONT WILL MOVE ACROSS LAKE
SUPERIOR TODAY AND SHIFT WINDS TO THE NORTHWEST...BRINGING THE
POTENTIAL FOR A FEW GALE FORCE GUSTS TO 35 KNOTS BEHIND THE FRONT
OVER THE EASTERN LAKE. A HIGH PRESSURE RIDGE WILL BUILD BACK INTO
THE AREA WEDNESDAY AND REMAIN INTO SATURDAY...LEADING TO GENERALLY
LIGHT WINDS BELOW 20KTS. ICE COVER IS EXTENSIVE...SO FREEZING SPRAY
IS NOT A PROBLEM.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
  GALE WARNING UNTIL 7 AM EST /6 AM CST/ THIS MORNING FOR LSZ162-
     263-264-266.

LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...JLB
LONG TERM...KF
AVIATION...JLB
MARINE...JLB



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