Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 220702
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
302 AM EDT WED APR 22 2015

.UPDATE...
ISSUED AT 1114 PM EDT TUE APR 21 2015

PREVIOUS SHORT TERM DISCUSSION SPELLED OUT THE SITUATION QUITE WELL
FOR OVERNIGHT INTO WED. AFTER CONSIDERING THE DEEP MOISTURE ON 00Z
KINL/CWPL SOUNDINGS...850MB TEMPS FALLING AT LEAST ANOTHER 2C
OVERNIGHT AND CONTINUED CYCLONIC FLOW...FEEL ADVY ACCUMULATIONS ARE
LIKELY TO OCCUR OVER A DECENT AREA OF GOGEBIC/ONTONAGON COUNTIES...
IN PARTICULAR THE HIGH TERRAIN. WOULD NOT BE SURPRISED TO SEE A FEW
SPOTS IN THE HIGH TERRAIN TOP 5 INCHES BY NOON WED. PROBABLY COULD
HAVE EXTENDED ADVY N AND E THRU THE KEWEENAW AND INTO BARAGA COUNTY
AS AIR MASS PASSING OVER THE LAKE WILL BE A LITTLE COLDER THAN DOWN
TOWARD KIWD. RECENT RADAR TRENDS ARE ALSO A CONCERN WITH INCREASING
COVERAGE AND INTENSITY OF SNOW IN THAT AREA. ALSO BUMPED UP SNOW
ACCUMLATIONS INTO THE ERN FCST AREA...E OF MARQUETTE AS 850MB
THERMAL TROF WITH TEMPS AS LOW AS -14C WILL BE AIMING SE ACROSS THE
LAKE AND INTO THAT AREA WED MORNING. HAVE AMOUNTS UP TO AROUND 3
INCHES IN THAT AREA BY LATE WED MORNING...BUT THAT COULD END UP
BEING TOO CONSERVATIVE.
&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 352 PM EDT TUE APR 21 2015

12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW CLOSED UPR LO OVER
THE UPR LKS DOWNSTREAM OF HI AMPLITUDE UPR RDG OVER WRN NAMERICA.
COMBINATION OF DEEP CYC FLOW W TO NW FLOW AND INSTABILITY ENHANCED
BY DAYTIME HEATING UNDER ACCOMAPANYING THERMAL TROF /12Z H5 TEMP AT
GRB WAS -31C/ AND DEEP MSTR SHOWN ON THE 12Z RAOBS IS RESULTING IN
SCT-NMRS SN SHOWERS THAT ARE MIXED WITH RA IN THE WARMER LOCATIONS.
BUT COLDER CLD TOP TEMPS/MORE WIDESRPEAD SN SHOWERS ARE CONFINED
MAINLY TO NW ONTARIO/FAR NRN MN IN AREA WHERE MODELS INDICATE DEEP
QVECTOR CNVGC.

MAIN FCST CONCERNS IN THE SHORT TERM FOCUS ON POPS AND POTENTIAL SN
ACCUMS ASSOCIATED WITH DEEP CYC...MOIST NW FLOW ARND SLOW MOVING
CLOSED LO TO THE NE OF UPR MI.

CLOSED LO CENTERED OVER ERN LK SUP THIS AFTN IS FCST TO DRIFT SLOWLY
TO THE NE AND TO JUST S OF JAMES BAY ON WED. ALTHOUGH ACCOMPANYING
DEEP LYR QVECTOR CNVGC THAT IS SUPPORTING COLDER CLD TOPS TO THE NW
IS FCST TO REMAIN TO THE N OF UPR MI...PERSISTENT MOIST...CYC NW
FLOW ARND THIS FEATURE WL MAINTAIN AT LEAST CHC POPS OVER THE CWA
THRU WED...WITH THE LOWER POPS GENERALLY OVER THE SCENTRAL AND THE
HIER POPS OVER THE HIER TERRAIN OF THE NW WITH UPSLOPE WIND
COMPONENT. BUT LOSS OF DAYTIME HEATING TNGT WL CAUSE THE
CHARACTER OF THE SHOWER PATTERN TO TRANSITIONS FM ONE THAT SUPPORTS
THE HIER POPS OVER THE INTERIOR THIS AFTN TO A MORE WINTRY LES
LOOK TNGT. IN FACT...THE NW FLOW IS PROGGED TO ADVECT H85 TEMPS AS
LO AS -13 TO -14C OVER THE KEWEENAW BY 12Z WED...TEMPS LO ENUF TO
SUPPORT LES AND INCRS SN/WATER RATIOS ONCE THE EFFECT OF DAYTIME
INSOLATION HAS FADED. OVER THE HIER TERRAIN OF THE W...THERE WL
LIKELY BE SEVERAL INCHES OF WET SN ACCUM TNGT INTO WED MRNG EVEN IN
THE ABSENCE OF SGNFT LARGER SCALE FORCING. OPTED TO ISSUE AN SPS
TO ALERT THE PUBLIC TO THE POTENTIAL OF SOME SLUSHY SN ACCUMS ON
ROADS LATER THIS EVNG INTO WED MRNG. DAYTIME HEATING ON WED WL
BRING ABOUT A RETURN TO A MORE LAND BASED INSTABILITY SHOWER
PATTERN. BUT SOMEWHAT HIER HGTS/SHARPENING MID LVL INVRN FARTHER FM
THE SLOWLY DEPARTING CLOSED LO THAT RESTRICTS DESTABILIZATION WL
TEND TO LIMIT COVERAGE/INTENSITY OF THE SHOWERS AS COMPARED TO TODAY.
ALTHOUGH H85 TEMPS ARE FCST TO MODERATE TO -10C TO -12C...MAX TEMPS
ON WED WL HOLD IN THE 30S EXPECT WHERE SOME DOWNSLOPE WARMING AIDS
DIURNAL TEMP RECOVERY INTO THE LO 40S OVER THE SCENTRAL. THERE COULD
BE SOME RECORD LO MAX TEMPS ON WED.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 302 AM EDT WED APR 22 2015

NAM SHOWS A TROUGH OVER THE EASTERN U.S. 12Z THU WITH MORE TROUGHING
ACROSS THE WEST COAST AND A SHORTWAVE RIDGE OVER THE PLAINS. NAM
SHOWS SOME WEAK 850-500 MB Q-VECTOR CONVERGENCE MOVING THROUGH THE
CWA ON THU WITH MOISTURE MOVING OUT IN THE AFTERNOON. AS THE
SHORTWAVE RIDGE MOVES TOWARDS THE AREA AND A TROUGH OVER THE EASTERN
U.S. MOVES AWAY...THE WRAPAROUND LAKE ENHANCED PCPN WILL SLOWLY WIND
DOWN AND HAVE IT DRYING OUT FRI AND FRI NIGHT WITH SLOWLY
DIMINISHING POPS IN THE CENTRAL AND EAST ON THU INTO THU NIGHT.
OVERALL...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST FOR
TEMPERATURES OR POPS.

IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB LOW OVER THE CENTRAL
PLAINS 12Z SAT WITH MORE TROUGHING IN THE WESTERN U.S. THE 500 MB
LOW AND TROUGH IN THE CENTRAL PLAINS GETS SHEARED OUT BY 12Z SUN AND
IS REPLACED BY A SHORTWAVE RIDGE THAT MOVES INTO THE UPPER GREAT
LAKES. THE RIDGE REMAINS OVER THE UPPER GREAT LAKES ON MON WITH
TROUGHING MOVING INTO THE NORTHERN PLAINS. THIS TROUGHING MOVES INTO
THE UPPER GREAT LAKES 12Z TUE. TEMPERATURES WILL STAY BELOW NORMAL
THIS FORECAST PERIOD. WILL CONTINUE WITH DRY WEATHER SAT THROUGH SUN
NIGHT AND THEN GO WITH SLIGHT CHANCE POPS MON THROUGH TUE AS A SFC
FRONT IS WELL OFF TO THE WEST AT THAT TIME AND PRODUCES SOME OVER
RUNNING PCPN THAT IS OFF TO THE WEST MOSTLY.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1231 AM EDT WED APR 22 2015

AS DEEP MOISTURE LINGERS AND COLDER AIR ARRIVES OVERNIGHT...SHSN
WILL INCREASE IN FREQUENCY AND INTENSITY AT KIWD/KCMX UNDER USPLOPE
NW WIND OFF LAKE SUPERIOR. EXPECT PREVAILING IFR CONDITIONS AT BOTH
TERMINALS THRU MID MORNING. TYPICAL FOR SHSN...THERE WILL BE
FLUCTUATION WITH SOME BRIEF PERIODS OF LIFR AND MVFR...THOUGH LIFR
MAY BE MORE FREQUENT IN THE FEW HRS EITHER SIDE OF SUNRISE. INTO THE
AFTN...EXPECT IMPROVEMENT TO MVFR AS SHSN INTENSITY DIMINISHES.
DOWNSLOPE NATURE OF THE NW FLOW WILL WORK TO LIMIT THE POTENTIAL FOR
LOWER VIS/CIG AT KSAW. WHILE MVFR CONDITIONS SHOULD PREVAIL...THERE
MAY BE BRIEF PERIODS OF IFR THRU MID MORNING. MVFR CONDITIONS WILL
PERSIST AT ALL TERMINALS THRU THIS EVENING.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 305 PM EDT TUE APR 21 2015

NORTHWESTERLY WINDS UP TO 30 KNOTS WILL CONTINUE OVER LAKE SUPERIOR
THROUGH THURSDAY MORNING. THERE COULD BE A FEW PERIODS OF GALE
FORCE GUSTS TO 35KTS LATE TONIGHT INTO WEDNESDAY...BUT THEY
SHOULDN/T BE WIDESPREAD. HIGH PRESSURE WILL BEGIN TO BUILD INTO
WESTERN LAKE SUPERIOR THURSDAY AFTERNOON/NIGHT AND LEAD TO
GRADUALLY DIMINISHING WINDS INTO FRIDAY. LIGHT NORTHERLY WINDS UP
TO 15KTS ARE EXPECTED THIS WEEKEND.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
  WINTER WEATHER ADVISORY UNTIL NOON EDT /11 AM CDT/ TODAY FOR
     MIZ002-009.

LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

UPDATE...ROLFSON
SHORT TERM...KC
LONG TERM...07
AVIATION...ROLFSON
MARINE...SRF



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