Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 260417
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1217 AM EDT THU MAR 26 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 300 PM EDT WED MAR 25 2015

A NEGATIVELY TILTED SHORTWAVE TROUGH ALOFT HAS MOVED INTO THE CWA
AHEAD OF AN UPPER TROUGH OVER CENTRAL CANADA. THE SHORTWAVE AND
ASSOCAITED 1002MB SFC LOW JUST N OF THE MN ARROWHEAD ARE RESULTING
IN AN AREA OF SNOW FROM NCENTRAL UPPER MI TO FAR NW WI AND NE MN.
THE SHORTWAVE/SFC LOW WILL MOVE TO NE OF LAKE SUPERIOR BY 00Z THU
AND MORE QUICKLY OFF TO THE NE LATER WED NIGHT. AS THE SYSTEM MOVE
NE...A TROUGH/COLD FRONT WILL SWEEP ACROSS THE CWA FROM THE NW
BETWEEN 03Z AND 12Z THU. 850MB TEMPS WILL DROP TO -15C BEHIND THE
FRONT BY 12Z THU...FALLING ANOTHER 2-3 DEGREES ON THU AS ANOTHER
SHORTWAVE IMMEDIATLY FOLLOWS THE FRONT AND THE UPPER TROUGH MOVES
OVERHEAD BY 00Z FRI.

THESE FEATURES WILL BE SUFFICIENT TO KEEP PRECIP /MOSTLY SNOW/ IN
THE FORECAST THROUGH THIS EVENING. MORE OF A TRANSITION TO LAKE
ENHANCED/UPSLOPE SNOW LATER THIS EVENING AND TONIGHT...CONTINUING
THROUGH THU. WITH THE RATHER COMPLICATED LIST OF ENERGY SOURCES
/SHORTWAVES...COLD FRONT...UPPER TROUGH/...EXACT SNOWFALL AMOUNTS
ARE A BIT MORE UNCERTAIN. THAT BEING SAID...DO NOT SEE A REASON WHY
NWRN UPPER MI /GENERALLY IRONWOOD TO COPPER HARBOR AND IN THE HIGHER
TERRAIN OF BARAGA COUNTY AROUND HERMAN/ WILL NOT SEE THE 3 INCH
SNOWFALL CRITERIA FOR A WINTER WEATHER ADVISORY. IN ADDITION TO THE
SNOWFALL...WINDS WILL INCREASE TONIGHT WITH GUSTS TO 30-35MPH NEAR
LAKE SUPERIOR AND OVER THE KEWEENAW TONIGHT INTO THU...LEADING TO
BLOWING SNOW...ESPECIALLY OVER THE KEWEENAW WHERE SNOWFALL WILL BE
BETTER. 24 HOUR AMOUNTS WILL BE GREATEST OVER THE HIGHER TERRAIN
NEAR LAKE SUPERIOR...WITH AMOUNTS OF 4-8 INCHES IN THE
AFOREMENTIONED NWRN UPPER MI AREAS AND 2-5 INCHES EAST OF BIG BAY.
HIGH TEMPS WILL RANGE FROM THE LOW-MID 20S OVER NWRN UPPER MI TO THE
MID 30S OVER THE FAR SCENTRAL. ADDITIONAL LIGHT SNOWFALL AMOUNTS ARE
EXPECTED THU NIGHT...SEE LONG TERM DISCUSSION FOR MORE DETAILS.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 451 PM EDT WED MAR 25 2015

FAIRLY PROGRESSIVE WEATHER PATTERN SETTING UP OVER THE NRN CONUS IN
THE EXTENDED PERIOD. PERIOD WILL BE CHARACTERIZED BY COLDER THAN
NORMAL TEMPS THU NIGHT/FRI AS ERN CONUS TROF ALLOWS FOR CONTINUED
INTRUSION OF ARCTIC AIR INTO THE UPPER GREAT LAKES AND LINGERING LES
NEAR LAKE SUPERIOR IN NORTH FLOW. TEMPS WILL MODERATE BY THE WEEKEND
AS SHORTWAVE RIDGE MOVES ACROSS THE AREA. WEATHER FOR FIRST HALF OF
NEXT WEEK WL THEN BE HIGHLIGHTED BY WARMER PACIFIC FLOW AND ABOVE
NORMAL TEMPS WITH TWO MAIN SHORTWAVES FCST TO BRING PCPN INTO THE
UPPER GREAT LAKES SUN/SUN NIGHT AND THEN AGAIN TUE NIGHT/WED.

BEGINNING THU NIGHT....850MB THERMAL TROF WITH TEMPS AROUND -20C
SAGS ACROSS THE AREA. PASSING WEAK SHORTWAVE COULD PROVIDE SOME WEAK
ENHANCEMENT TO LES THOUGH MODELS DON`T SHOW MUCH IMPACT ON MOISTURE
OR INVERSION HEIGHT WHICH REMAINS AROUND 5KFT. INVERSION HGTS LOWER
TO AOB 3FT BY LATE THU NIGHT WITH INCREASED SUBSIDENCE FM STRONG
HIGH PRES BUILDING IN FM NW OF LAKE SUPERIOR. EXPECT ANOTHER 1 OR 2
INCHES OF SNOW IN THE N WIND FAVORED AREAS. SINCE DGZ OCCUPIES A
GOOD PORTION OF THE CONVECTIVE LAYER...WOULDN`T BE TOO SURPRISED TO
SEE LOCALIZED HIGHER AMOUNTS.

AS MIDLEVEL TROF SHIFTS E ON FRI...CENTER OF ARCTIC HIGH PRES WILL
DRIFT SE OVER THE WESTERN GREAT LAKES REGION. INCREASED
DRYING/MODERATION OF AIR MASS AND THE DISRUPTIVE EFFECT OF LATE
MARCH SOLAR HEATING WILL BRING AN END TO LIGHT LES DURING THE DAY
FROM W TO E. WITH THE SFC HIGH DRIFTING ACROSS THE AREA FRI
NIGHT...EXPECT A VERY COLD LATE MARCH NIGHT UNDER CALM WIND AND DRY
AIR MASS (PRECIPITABLE WATER UNDER ONE-TENTH OF AN INCH). RECENT
ADDITION OF NEW SNOW ON THE GROUND IN MANY AREAS WILL FURTHER AID
RADIATIONAL COOLING. WL FAVOR THE COLDEST END OF AVBL MODEL GUIDANCE
WHICH SUGGESTS MANY INTERIOR LOCATIONS SHOULD FALL BLO ZERO. WOULD
THINK TEENS BLO ZERO CERTAINLY POSSIBLE IN THE TRADITIONAL COLDEST
SPOTS. A BLEND OF THE COLDER 12Z BIAS CORRECTED MODEL GUIDANCE
INDICATES A SMALL POCKET OF TEMPS NEAR -12F JUST NORTH OF NEWBERRY.

SAT WILL BE SUNNY AND WARMER WITH TEMPS MOVING CLOSER TO NORMAL
ESPECIALLY W AND SCNTRL. SOUTHERLY WINDS WILL BEGIN TO INCREASE
SAT...BUT MORE SO SAT NIGHT DUE TO TIGHTENING PRES GRADIENT BTWN
DEPARTING HIGH SLIDING TO THE SE AND SFC LOW PRES MOVING TO SRN
MANITOBA.

SUNDAY...THE LOW APPROACHING FM SCNTRL CANADA WILL BE ASSOCIATED
WITH A STRONG SHORTWAVE THAT WILL BE MOVING INTO THE UPPER LAKES.
MODELS FCST VIGOROUS DYNAMICS LATE SAT NIGHT INTO SUN WITH 12HR
500MB HEIGHT FALLS OF 180-200M. THIS ALONG WITH DEEP LAYER Q-VECT
CONV AND MODERATE TO STRONG ISENTROPIC ASCENT WILL SUPPORT PCPN
POSSIBLY AS EARLY AS LATE SAT NIGHT FOR WEST BUT MORE LIKELY SUNDAY
INTO SUNDAY NIGHT FOR MOST OF THE FCST AREA. GFS IS STILL A GOOD
6HRS FASTER THAN THE ECMWF/CANADIAN AND WOULD SPREAD PCPN ACROSS THE
ENTIRE FCST AREA OVERNIGHT SAT NIGHT WHEREAS THE ECMWF/CANADIAN HOLD
PCPN OFF UNTIL AFTER 12Z SUN. MIXING RATIOS OF 4G/KG ARE AVBL ON THE
295K SFC (725-750MB)...SO THERE COULD BE A QUICK BURST OF DECENT
SNOWFALL DURING THE SHORT-LIVED PEAK ISENTROPIC ASCENT (1-2 INCHES
OF SNOW). WHILE THERE IS SOME CONCERN FOR ENOUGH WARMING TO CAUSE
MIXED PTYPES...BELIEVE STRENGTH OF UPWARD MOTION AND TIME OF DAY
(ARRIVING LATE SAT NIGHT OR SUN MORNING) WILL MAKE THE INITIAL
PERIOD OF PCPN ALL SNOW. SYSTEM IS STILL FAR ENOUGH OUT THAT IT MAY
TAKE MODELS SEVERAL MORE RUNS TO SORT OUT ALL THE DETAILS. SFC LOW
TRACK OF ECMWF AND GFS GENERALLY IS ACROSS LAKE SUPERIOR WHILE THE
GEM-NH IS FARTHER NORTH OVER ONTARIO. WILL KEEP PCPN IN THE FCST
THRU SUN AND EVEN SUN NIGHT AS THERE ARE HINTS OF A SECONDARY WAVE
SWEEPING THROUGH THE AREA. AFTER THE INTIAL BURST OF SNOW WITH THE
STRONG ISENTROPIC ASCENT...ANY LIGHTER SNOW ESPECIALLY BY SUN
AFTERNOON SHOULD MIX WITH OR EVEN CHANGE TO RAIN FOR A TIME UNDER
DAYTIME HEATING...THEN CHANGE BACK TO SNOW UNDER CAA SUN NIGHT.
VIGOROUS SYSTEM SHOULD RESULT IN WINDY CONDITIONS FOR MUCH OF THE
AREA SUN INTO SUN NIGHT.

MAINLY DRY WEATHER WILL FOLLOW FOR MON...THEN WAA PATTERN AHEAD OF
THE NEXT SHORTWAVE APPROACHING THE NRN PLAINS MAY RESULT IN MIXED
PCPN EVENT TUE INTO WED. MODEL CONFIDENCE AT THIS TIME IS POOR AS
12Z ECMWF IS QUICKER AND DEEPER WITH SHORTWAVE SHOWING A GREATER
POTENTIAL FOR WIDESPREAD PCPN WHILE THE 12Z GFS AND GEM-NH SHOW A
WEAKER SHORTWAVE WITH ONLY LIGHT SCT PCPN FCST. AT THIS TIME GIVEN
LOW MODEL CONFIDENCE WL STICK WITH GENERALLY LOW CHC POPS.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1217 AM EDT THU MAR 26 2015

EXPECT GUSTY W VEERING NW WINDS ACCOMPANYING A COLD FROPA AS WELL AS
SOME DYNAMIC FORCING THAT MAINTAINS DEEP MSTR TO RESULT IN SHSN/BLSN
AND PREDOMINANT LIFR CONDITIONS AT CMX THRU ABOUT SUNRISE. GRADUALLY
DIMINISHING WINDS/BLSN WL CAUSE THESE AUSTERE CONDITIONS TO EASE ON
THU MRNG...BUT IFR CONDITIONS SHOULD REMAIN THE RULE UNTIL LARGER
SCALE SUBSIDENCE/DRYING/A DIMINISHING AND LESS FAVORABLE N WIND TO
BRING ABOUT MVFR CONDITIONS IN THE AFTN AND VFR CONDITIONS IN THE
EVNG.

WITH A WEAKER UPSLOPE WIND AT IWD AND PASSAGE OF THE DYNAMIC FORCING
FARTHER TO THE N...MVFR CONDITIONS SHOULD PREDOMINATE AT THIS SITE
UNTIL ABOUT SUNRISE WHEN THE WSHFT TO A MORE FAVORABLE NNW DIRECTION
FOLLOWING THE FROPA IS LIKELY TO BRING ABOUT SOME HEAVIER SHSN AND
IFR VSBYS. ALTHOUGH THE LARGER SCALE SUBSIDENCE/DRYING WL IMPACT
THIS LOCATION DURING THE AFTN AS AT CMX...THE DIMINISHING N WIND WL
PRESENT A MORE UPSLOPE WIND COMPONENT THAT MAINTAINS MVFR WX THRU
THE EVNG.

AT SAW...DOWNSLOPE NATURE OF THE W WIND WL BRING ABOUT VFR TO OCNL
MVFR CIGS EARLY THIS MRNG. BUT THE WSHFT TO A FAVORABLE NNW
DIRECTION FOLLOWING THE FROPA NEAR SUNRISE IN THE PRESENCE OF SOME
DYNAMIC FORCING/DEEP MSTR IS LIKELY TO BRING A PERIOD OF HEAVIER
SHSN/IFR VSBYS INTO THE AFTN BEFORE THE LARGER SCALE DRYING AND
SUBSIDENCE BRING ABOUT MVFR CONDITIONS IN THE MID/LATE AFTN TIME. AS
AT IWD...THE UPSLOPE N WIND SHOULD MAINTAIN MVFR CIGS AT SAW.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 300 PM EDT WED MAR 25 2015

AN AREA OF LOW PRESSURE ACROSS N MN WILL SHIFT E ACROSS ONTARIO BY
THE END OF THE DAY WHILE DEEPENING. A LINGERING TROUGH ACROSS LAKE
SUPERIOR WILL EXIT TO THE SE THURSDAY MORNING. A FEW N GALE FORCE
GUSTS TO 35KTS WILL BE POSSIBLE OVER MAINLY N AND CENTRAL LAKE
SUPERIOR THURSDAY MORNING...BEFORE SLOWLY DIMINISHING THROUGH THE
DAY.

EXPECT A LOW OVER MANITOBA ON THURSDAY TO BRIEFLY SETTLE ACROSS THE
UPPER GREAT LAKES FRIDAY INTO EARLY SATURDAY...AND CONTINUE TO THE
OHIO VALLEY SATURDAY NIGHT. LOW PRESSURE STRETCHING FROM HUDSON BAY
TO S MANITOBA SATURDAY NIGHT WILL THEN SWING ACROSS CENTRAL ONTARIO
AND LAKE SUPERIOR SUNDAY AFTERNOON...AND INTO QUEBEC SUNDAY NIGHT.
ANOTHER PERIOD OF GUSTS OF 35 KTS TO NEAR 40KT GUSTS OF THE SW TO W
WILL BE POSSIBLE LATE SATURDAY NIGHT THROUGH SUNDAY...AND LINGER
OVER THE E HALF OF LAKE SUPERIOR OUT OF THE NW AT 35KTS SUNDAY NIGHT.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
  WINTER WEATHER ADVISORY UNTIL 2 PM EDT /1 PM CDT/ THIS AFTERNOON
     FOR MIZ001>004-009.

LAKE SUPERIOR...
  GALE WARNING FROM 4 AM EARLY THIS MORNING TO 2 PM EDT THIS
     AFTERNOON FOR LSZ248-249-265-266.

LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...TITUS
LONG TERM...VOSS
AVIATION...KC
MARINE...TITUS



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