Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 240946
AFDMQT

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

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 233 PM EST MON FEB 23 2015

UPPER AIR PATTERN CONSISTS OF A CLOSED 500 MB LOW OVER THE GREAT
BASIN WITH AN ASSOCIATED TROUGH...A CLOSED LOW OVER QUEBEC WITH A
DEEP TROUGH OVER THE ERN U.S. THIS MORNING. THERE IS ALSO SOME UPPER
LEVEL ENERGY ACROSS CENTRAL CANADA THAT IS MOVING SOUTH AND IS
POISED TO CARVE OUT A DEEP UPPER TROUGH OVER THE AREA AGAIN WITH
COLDER AIR RETURNING.

NAM BRINGS IN SOME DEEPER MOISTURE AND 850-500 MB Q-VECTOR
CONVERGENCE TONIGHT BEFORE BOTH DEPART THE AREA TUE MORNING. DID NOT
MAKE TOO MANY CHANGES TO THE GOING FORECAST OVERALL FOR TEMPERATURES
OR WEATHER WITH THE ONLY CHANGE OF BACKING THE TIMING OF POPS UP
TONIGHT A BIT. TEMPERATURES WILL BE TRICKY AND LOWERED THEM ABOUT 2
DEGREES FOR TONIGHT BASED ON THE DRYNESS OF THE COLD AIR...BUT KEPT
THE TEMPERATURE CURVE THE SAME WITH A NON-DIURNAL WARMING TREND
TONIGHT AND THEN NON-DIURNAL TREND FOR TEMPERATURES ON TUE AS COLD
AIR ARRIVES IN THE AFTERNOON WHICH SHOULD HAVE TEMPERATURES FALLING.
NOT REAL CONFIDENT ABOUT LAKE EFFECT SNOW BEHIND THIS SYSTEM TONIGHT
AS THERE IS A LOT OF ICE COVER ON LAKE SUPERIOR NOW...CLOSE TO 95
PERCENT AND HARD TO SAY WHERE HEAT WILL BREAK THROUGH THE ICE TO
CAUSE LAKE EFFECT SNOW BANDS AND HOW MUCH HEAT FROM THE ICE IS
AVAILABLE. WE DO GET CLOSE TO ADVISORY SNOW IN A FEW PLACES IN THE
KEWEENAW AND ALSO IN THE EAST BETWEEN 06Z AND 18Z ON TUE...BUT
TAKING THE MID AMOUNTS GETS JUST UNDERNEATH CRITERIA AND WILL NOT
ISSUE ADVISORIES FOR THIS. OVERALL...GOING FORECAST WAS GOOD AND
MADE VERY FEW CHANGES TO IT.

.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 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1237 AM EST TUE FEB 24 2015

AN AREA OF -SN IN ADVANCE OF AN APRCHG COLD FNT WL OVERSPREAD UPR MI
EARLY THIS MRNG...BRINGING A PERIOD OF MVFR AND PERHAPS IFR
CONDITIONS. THE BEST CHC FOR PERSISTENT IFR VSBYS DUE TO THE FALLING
-SN AND SOME BLSN WHIPPED UP BY GUSTY SW WINDS WL BE AT CMX...CLOSER
TO THE TRACK OF THE ASSOCIATED SHRTWV AND DEEPER MSTR. ALTHOUGH
THERE MAY BE SOME IMPROVEMENT IMMEDIATELY FOLLOWING THE FROPA AND
STRONGER DYNAMIC FORCING AFTER SUNRISE THIS MRNG...A REINFORCING
DISTURBANCE AND ATTENDANT ARCTIC COLD FROPA WL BRING MORE SHSN/GUSTY
NW WINDS/BLSN IN THE AFTN IN THE PRESENCE OF DIURNAL HEATING AND CAA
THAT SHARPEN LLVL LAPSE RATES. ALTHOUGH EXTENSIVE ICE COVER WL LIMIT
THE INTENSITY OF THE LES...THE BLSN AT THE MORE EXPOSED CMX LOCATION
WL 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 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 233 PM EST MON FEB 23 2015

SOUTHWEST GALES AROUND 35 KTS OVER PORTIONS OF LAKE SUPERIOR WILL
CONTINUE LATE THIS AFTERNOON THROUGH TONIGHT. A COLD FRONT WILL MOVE
ACROSS LAKE SUPERIOR LATE TONIGHT INTO TUESDAY MORNING AND SHIFT
WINDS TO THE NORTHWEST...THERE MAY BE A FEW GALE FORCE GUSTS TO 35
KNOTS BEHIND THE FRONT ON TUESDAY OVER EASTERN LAKE SUPERIOR. 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...07
LONG TERM...KF
AVIATION...KC
MARINE...07


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