Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 221136
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
636 AM EST THU JAN 22 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 429 AM EST THU JAN 22 2015

A CLOUDY SKY COVERS ALL OF UPPER MICHIGAN EARLY THIS MORNING...AS
ABUNDANT LOW LEVEL MOISTURE REMAINS TRAPPED BELOW THE STRENGTHENING
SUBSIDENCE INVERSION (SEEN ON 00Z KINL SOUNDING) FROM THE HIGH
PRESSURE RIDGE OVER NORTHERN MINNESOTA. RAP ANALYSIS SHOWS A -12C
850MB THERMAL TROUGH SLIDING ACROSS CENTRAL/EASTERN LAKE SUPERIOR
EARLY THIS MORNING (ASSOCIATED WITH A SHORTWAVE MOVING THROUGH
NORTHERN ONTARIO AND BRUSHING NORTHERN LAKE SUPERIOR) AND AIDING
WEAK LAKE EFFECT SNOW SHOWERS IN THE NORTHWEST WIND SNOW BELTS OVER
EASTERN UPPER MICHIGAN. OVERALL THESE ARE FAIRLY WEAK AND DISJOINTED
DUE TO THE MARGINAL DELTA-T VALUES AND WEAK LOW LEVEL LAPSE RATES.
THOSE MARGINAL FEATURES HAVE ALSO LEAD TO OCCASIONAL PERIODS OF
FREEZING DRIZZLE LAST EVENING OVER THE KEWEENAW AND ALSO OVER THE
NORTH CENTRAL THROUGH THE NIGHT. WILL INCLUDE A PATCHY FREEZING
DRIZZLE MENTION FOR THE NEXT COUPLE OF HOURS...BUT EXPECT THERE TO
BE LITTLE TO NO IMPACT WITH THE PRECIP BEING PREDOMINATELY SNOW.
UNDER THE CLOUDY SKIES...TEMPERATURES HAVE BEEN SLOW TO FALL THROUGH
THE NIGHT...WITH 3AM TEMPERATURES STILL IN THE LOWER 20S.

THE HIGH PRESSURE RIDGE OVER MINNESOTA WILL QUICKLY SLIDE EAST
ACROSS UPPER MICHIGAN TODAY...AS THE PARENT HIGH MOVES FROM THE
CENTRAL PLAINS TO THE OHIO RIVER VALLEY. THIS WILL LEAD TO STEADILY
BACKING LOW LEVEL WINDS THIS MORNING AND SHIFT ANY REMAINING LAKE
EFFECT SNOW OVER THE EAST OFFSHORE. THE BIGGEST QUESTION WITH THE
FORECAST TODAY IS WHAT WILL HAPPEN TO THE CLOUDS. MOST MODELS ARE
INDICATING THAT THE LOW CLOUDS WILL SCATTER OUT LATE THIS MORNING
AND INTO THE AFTERNOON. DO HAVE SOME CONCERN WITH THAT DUE TO THE
UPSTREAM OBS STILL INDICATING LOW CLOUDS INTO EASTERN MINNESOTA AND
WESTERN WISCONSIN...ALONG WITH THE STRENGTHENING SUBSIDENCE
INVERSION ASSOCIATED WITH THE HIGH PRESSURE RIDGE MOVING THROUGH.
BUT WITH THE SOUTHWESTERLY FLOW INCREASING MIXING AND THE MOISTURE
LAYER BECOMING THIN...DID TREND THE FORECAST TOWARDS PARTLY CLOUDY.
THIS SITUATIONS ARE TRICKY...AS SOME AREAS WILL LIKELY CLEAR OUT
COMPLETELY (AIDED BY DOWNSLOPING SOUTHWESTERLY WINDS) WHILE THERE
COULD STILL BE POCKETS OF CLOUDY SKIES. AS THE LOW CLOUDS SCATTER
OUT...HIGH CLOUDS WILL BE THICKENING OVER THE AREA THIS
AFTERNOON/EVENING ASSOCIATED WITH THE APPROACHING CLIPPER SYSTEM.
THUS...WILL GRADUALLY INCREASE THE CLOUDS FROM THE NORTHWEST LATE
THIS AFTERNOON AND CONTINUE THROUGH THE NIGHT. LOWS WILL OCCUR THIS
EVENING AND THEN GRADUALLY WARM OVERNIGHT WITH THE INCREASING
SOUTHWESTERLY FLOW. THAT SOUTHWEST FLOW...WHICH WILL PRODUCE GALES
OVER WESTERN/CENTRAL LAKE SUPERIOR...IS EXPECTED TO LEAD TO GUSTY
CONDITIONS DEVELOPING OVER THE FAR WEST THIS AFTERNOON AND ACROSS
THE AREA TONIGHT. THINK THE STRONGEST GUSTS WILL REMAIN TOWARDS ISLE
ROYALE WHERE THE BEST PRESSURE FALLS ARE LOCATED...BUT STILL SHOULD
SEE SOME GUSTS TO 20-25KTS (AND 30KTS OVER THE KEWEENAW) TONIGHT.

AS THE COLD FRONT ASSOCIATED WITH THE CLIPPER SYSTEM APPROACHES LAKE
SUPERIOR TONIGHT...SHOULD SEE PRECIPITATION DROPPING SOUTHEAST
ACROSS WESTERN/CENTRAL LAKE SUPERIOR OVERNIGHT. SHOULD SEE IT
IMPACTING THE KEWEENAW PENINSULA BETWEEN 9-12Z. HAVE KEPT
PRECIPITATION AS SNOW FOR MOST LAND LOCATIONS THROUGH 12Z...BUT WITH
THE NAM INDICATING A WARM NOSE MOVING INTO WESTERN LAKE SUPERIOR
TOWARDS 12Z...DID ADD A MENTION OF FREEZING RAIN AND SLEET TO THAT
AREA.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 524 AM EST THU JAN 22 2015

A PERSISTENT RIDGE OVER THE WRN CONUS WILL MAINTAIN NW MID/UPPER
LEVEL FLOW ACROSS THE NRN GREAT LAKES THROUGH THE MIDDLE OF NEXT
WEEK. THIS WILL BRING A SERIES OF CLIPPERS INTO THE REGION. IT
APPEARS AT THIS TIME ANY LES FROM THESE CLIPPERS WOULD BE LIGHT AS
ONLY MARGINAL INSTABILITY IS EXPECTED WITH THE COLDEST AIR
REMAINING OVER NE CANADA.

FRIDAY...MODELS FCST QVECTOR CONV AHEAD OF A SHORTWAVE TROUGH ALONG
WITH 280K-290K ISENTROPIC LIFT SHOULD BE STRONG ENOUGH TO SQUEEZE
OUT SOME LIGHT PCPN INTO PORTIONS OF UPPER MI. THERE IS STILL SOME
UNCERTAINTY WITH THE PCPN AMOUNTS/PLACEMENT. HOWEVER...THE STRONGER
FORCING IS EXPECTED TO MOVE THROUGH DURING THE MORNING WITH DRYING
DURING THE AFTERNOON. THE NAM...WHICH OFTEN PERFORMS BETTER WITH
DEVELOPING WARM LAYERS ALOFT...SUGGESTS THAT THE PCPN OVER THE WEST
HALF COULD BE MIXED WITH FREEZING RAIN OR SLEET AS THE MAX TEMP
ALOFT CLIMBS TO AROUND 3C(NEAR 900 MB). THE POSITION OF THE WARM
NOSE WOULD BRING THE BEST CHANCE FOR ANY ICING OVER MAINLY JUST THE
FAR WEST. OTHERWISE...TEMPS WILL CLIMB WELL ABOVE NORMAL WITH MAX
READINGS INTO THE MID 30S.

FRI NIGHT... COLDER AIR WILL ONLY GRADUALLY MOVE IN FRI NIGHT WITH
NW WINDS BEHIND A SFC TROUGH AS 850 MB TEMPS DROP TO -6C TO -8C BY
12Z/SAT. SOME LIGHT LAKE ENHANCED SNOW IS POSSIBLE FOR NW FLOW
FAVORED LOCATIONS AS A WEAK SHORTWAVE MOVES THROUGH WITH DEEPER
MOISTURE OVER THE AREA. OTHERWISE...WRLY FLOW OF PACIFIC AIR BEHIND
THE SFC TROUGH WILL KEEP TEMPS FROM DROPPING OFF MUCH WITH MANY
LOCATIONS NOT DROPPING MUCH BELOW 30F...ESPECIALLY FOR DOWNSLOPE
FLOW LOCATIONS.

SAT...MARGINALLY COLD AIR WITH 850 MB TEMPS FALLING TO -10C TO
-12C WILL MOVE IN AS A RIDGE BUILDS INTO THE WRN LAKES. DIMINISHING
LOW LEVEL WINDS BECOMING MORE ANTICYCLONIC AND NRLY WITH TIME WILL
ALSO LIMIT POTENTIAL FOR LES ACCUMULATIONS CONSISTENT WITH ONLY
CHANCE POPS.

SAT NIGHT AND SUN...THERE IS STILL SOME MODEL UNCERTAINTY WITH THE
TRACK OF THE NEXT CLIPPER SYSTEM. THE ECMWF REMAINS FARTHEST TO THE
WEST AND SOUTH WITH LITTLE PCPN INTO UPPER MICHIGAN WHILE THE
CANADIAN BRINGS THE HEAVIER PCPN THROUGH THE CWA. SOME AREAS IN THE
REGION COULD SEE SNOWFALL INTO THE 1 TO 4 INCH RANGE WITH THE SYSTEM.
THE GFS REPRESENTS A COMPROMISE KEEPING THEPCPN OVER WEST UPPER
MICHIGAN. WILL CONTINUE ALONG WITH CONSENSUS FCST WHICH KEEPS CHANCE
POPS ACROSS THE WEST.

MON INTO WED...ANOTHER CLIPPER SYSTEM IS EXPECTED TO MOVE INTO THE
REGION BY LATE MON OR MON NIGHT BUT THE MODELS HAVE TRENDED WEAKER
WITH THIS SHRTWV WITH ONLY LIGHT PCPN REMAINING WEST OF UPPER MI.
SFC RIDGING INTO THE AREA WITH LIGHT WINDS WILL ALSO NOT BE
FAVORABLE FOR LES.
&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 635 AM EST THU JAN 22 2015

MVFR CLOUDS WILL CONTINUE THROUGH THE MORNING FOR THE TAF
SITES...AS A HIGH PRESSURE RIDGE QUICKLY SHIFTS EAST ACROSS UPPER
MICHIGAN. BEHIND THE RIDGE...WINDS WILL BACK TO THE SOUTHWEST AND
GRADUALLY INCREASE THIS AFTERNOON AND EVENING AHEAD OF A CLIPPER
SYSTEM THAT WILL AFFECT KCMX LATE TONIGHT AND THE OTHER SITES ON
FRIDAY. AS THE WINDS BACK TO THE SOUTHWEST AND THE CLOUDS BECOME
PINCHED BY DRY AIR ALOFT...EXPECT CLOUDS TO BEGIN SCATTERING OUT
THIS AFTERNOON. THIS SHOULD OCCUR FIRST AT KIWD/KSAW WITH THE
DOWNSLOPING FLOW AND THEN AT KCMX. WITH THE ABUNDANT MOISTURE TO
THE SOUTHWEST OF THE AREA...THERE IS THE POTENTIAL THE MVFR CLOUDS
BECOME TRAPPED BELOW THE INVERSION AND DELAY THE DEPARTURE A FEW
HOURS.

FOR TONIGHT...EXPECT GUSTY SOUTHWEST WINDS AND WITH THE STRONG
WINDS JUST ABOVE THE SURFACE...DID INCLUDE WIND SHEAR FOR ALL THREE
SITES. SNOW FROM THE CLIPPER SYSTEM WILL ARRIVE LATE TONIGHT AT
KCMX AND HAVE BROUGHT CONDITIONS BACK DOWN TO MVFR.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 429 AM EST THU JAN 22 2015

A HIGH PRESSURE RIDGE WILL QUICKLY SLIDE EAST ACROSS THE UPPER
GREAT LAKES REGION THIS MORNING...STEADILY BACKING WINDS TO THE
SOUTHWEST. AS THE PRESSURE GRADIENT TIGHTENS THIS AFTERNOON AND
TONIGHT AHEAD OF A LOW PRESSURE SYSTEM MOVING THROUGH NORTHERN
MANITOBA AND NORTHERN ONTARIO...EXPECT SOUTHWESTERLY GALES OF
35-40KTS OVER PORTIONS OF WESTERN AND CENTRAL UPPER MICHIGAN. BASED
OFF THE STRENGTH OF THE WINDS JUST ABOVE THE SURFACE...WOULDN/T BE
SURPRISED TO SEE SOME 45KT GUSTS AT THE HIGHER PLATFORMS AROUND
ISLE ROYALE. THE GALE WARNING THAT IS IN PLACE LOOKS TO BE IN DECENT
SHAPE...ALTHOUGH DID EXPAND IT SOUTHWEST TO LSZ162. A COLD FRONT
ASSOCIATED WITH THE LOW WILL SWEEP SOUTHEAST ACROSS LAKE SUPERIOR
ON FRIDAY...SHIFTING THE WINDS TO THE NORTHWEST AND BRINGING AN END
TO THE GALES. BEHIND THE FRONT...EXPECT WINDS TO 25-30KTS BEFORE
SHIFTING MORE NORTHERLY BEHIND A SECONDARY TROUGH ON MOVING ACROSS
LAKE SUPERIOR ON SATURDAY. WINDS WILL DIMINISH BEHIND THE SECONDARY
TROUGH AS A HIGH PRESSURE RIDGE SHIFTS SOUTH INTO THE AREA
SATURDAY NIGHT. ANOTHER CLIPPER SYSTEM WILL MOVE OUT OF CANADA AND
THROUGH THE UPPER MISSISSIPPI VALLEY ON SATURDAY NIGHT AND THEN
SLIDE THROUGH WISCONSIN SUNDAY MORNING. THIS WILL KEEP WINDS UP TO
20KTS OUT OF THE NORTH-NORTHEAST. ANOTHER RIDGE WILL BUILD IN
BEHIND THIS CLIPPER AND KEEP WINDS 15KTS OR BELOW SUNDAY NIGHT INTO
MONDAY.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
  GALE WARNING FROM 6 PM THIS EVENING TO 9 AM EST FRIDAY FOR
     LSZ263-264.

LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...SRF
LONG TERM...JLB
AVIATION...SRF
MARINE...SRF


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