Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 200716
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
316 AM EDT MON APR 20 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 316 AM EDT MON APR 20 2015

UPPER AIR PATTERN CONSISTS OF A ELONGATED 500 MB TROUGH WITH SEVERAL
SHORTWAVES EMBEDDED IN IT. THE SHORTWAVE OVER LOWER MICHIGAN WILL BE
SPREADING PCPN UP INTO THE CWA THIS MORNING WHILE ANOTHER SHORTWAVE
OVER THE RED RIVER VALLEY OF THE NORTH WILL PUT PCPN IN OVER THE FAR
WEST THIS MORNING. BOTH THESE SHORTWAVES WILL COMBINE OVER THE AREA
AND CAUSE SOME WIDESPREAD PCPN THIS MORNING OVER THE CWA. UPPER
TROUGH SLOWLY MOVES EAST WITH A 500 MB LOW MOVING OVER THE U.P. LATE
TONIGHT. NAM SHOWS DEEPER MOISTURE AND 850-500 MB Q-VECTOR
CONVERGENCE OVER THE CWA THIS MORNING. THE DEEPER MOISTURE REMAIN
OVER THE AREA THROUGH TONIGHT WHILE THE Q-VECTOR CONVERGENCE WEAKENS
AND MOVES OUT BY THIS EVENING BEFORE MOVING BACK IN LATE TONIGHT
WITH THE 500 MB LOW. GFS AND ECMWF SHOW ABOUT THE SAME THING AS
WELL.

HAD TO HANG ONTO THE DRIER AIR ACROSS THE CENTRAL CWA A BIT LONGER
THIS MORNING AND CUT THE QPF AMOUNTS BECAUSE OF THIS. DID GO WITH A
COMBO OF WET BULB HEIGHTS AND WARM TEMPERATURES ALOFT TO DETERMINE
SNOW FOR THIS FORECAST AND LOOKS LIKE THE ACCUMULATING SNOW WILL BE
TONIGHT WHERE UP TO 2 INCHES COULD FALL ACROSS THE WESTERN
HIGHLANDS. OTHERWISE...DID NOT MAKE TOO MANY CHANGES TO THE GOING
TEMPERATURE FORECAST AND WENT WITH CATEGORICAL POPS FOR TODAY FOR
THE CWA AND THEN LIKELY POPS IN NORTHWEST LAKE EFFECT BELTS TONIGHT
AND KEPT SOME SLIGHT CHANCE POPS IN THE FAR SOUTH DUE TO THE UPPER
LOW MOVING INTO THE AREA AND WRAPAROUND PCPN IN THE AREA.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 423 PM EDT SUN APR 19 2015

THE PATTERN WILL BE DOMINATED BY A MID/UPPER LEVEL LOW MOVING SLOWLY
THROUGH THE GREAT LAKES BRINGING UNSETTLED WEATHER ALONG WITH BELOW
NORMAL TEMPERATURES. THE LOW SHOULD FINALLY SHIFT TOWARD ERN CANADA
AND NEW ENGLAND BY THE WEEKEND LEAVING NW FLOW IN PLACE WITH
CONTINUED BELOW NORMAL TEMPERATURES.

MON NIGHT THROUGH TUE NIGHT...MODELS SUGGEST THAT THE MID LEVEL LOW
WILL SLOWLY WOBBLE INTO THE NRN GREAT LAKES. WITH THE COMBINATION OF
DEEP MOISTURE AND WEAK SHORTWAVES NEAR THE LOW...EXPECT INCREASING
PCPN CHANCES AS MAINLY SNOW...PER FCST SOUNDINGS. THERE MAY BE SOME
ADDITIONAL LAKE ENHANCED (850 MB TEMPS DROP TO AROUND -8C) INTO THE
HIGHER TERRAIN OVER THE WEST WITH UPSLOPE WNW FLOW. SNOW
ACCUMULATIONS OF A FEW INCHES ARE POSSIBLE...MAINLY ON GRASSY
SURFACES. HOWEVER...WITH THE ARRIVAL OF THE SNOW OVERNIGHT SOME
ACCUMULATION ON ROADS MAY ALSO CREATE HAZARDOUS TRAVEL TUE MORNING.
DAYTIME HEATING TUE MAY ENHANCE THE PCPN OVER INLAND AREAS WITH STEEP
SFC-700MB LAPSE RATES DEVELOPING. WITH TEMPS CLIMBING TO AROUND
40F...THE PCPN MAY MIX WITH RAIN OVER THE SE HALF OF THE CWA. 12Z NAM
FCST WET-BULB ZERO HEIGHTS WERE USED TO DELINEATE PCPN TYPE. ANOTHER
INCH OR TWO OF SNOW WILL BE POSSIBLE MAINLY OVER THE NW WIND
SNOWBELTS IN THE WEST TUE NIGHT AS 850 MB TEMPS DROP TO AROUND -12C
WHILE THE DEEP MOISTURE AND LOW LEVEL CYCLONIC FLOW REMAIN IN PLACE.

WED-THU...THE LARGE COLD MID-LEVEL LOW WILL ONLY SLOWLY SHIFT TO THE
ESE TO THE ERN LAKES BY LATE THU. COLD AIR ALOFT/SPRING DAYTIME
HEATING AND POTENTIAL OF SHORTWAVES ROTATING THROUGH THE AREA WITHIN
THE LARGE MID-LEVEL LOW CIRCULATION FAVORS AT LEAST SCT SHOWERY
PCPN... MOSTLY AS SNOW BUT POSSIBLY MIXING WITH RAIN SOUTH DURING
PEAK HEATING. ALTHOUGH THERE WILL BE SOME LAKE CONTRIBUTION AS 850
MB TEMPS RANGE FROM -10C TO -13C...THE BEST COVERAGE DURING THE
DAYTIME SHOULD BE IN THE AFTERNOON INLAND FROM LAKE SUPERIOR WHERE
HEATING WILL BE STRONGEST. HIGH TEMPS BOTH DAYS SHOULD BE WELL BELOW
NORMAL...IN THE MID 30S TO LOWER 40S...WARMEST S CNTRL.

FRI-SUN...FCST UNCERTAINTY IS GREATER AS THE GFS/GEFS/GEM MAINTAIN
TROUGHING INTO NRN ONTARIO AND THE NRN LAKES THROUGH THE WEEKEND
WHILE THE ECMWF BRINGS A RIDGE TOWARD THE WRN LAKES WITH DRIER AND
WARMER CONDITIONS. WITH EITHER SCENARIO...TEMPS ARE EXPECTED TO
REMAIN BELOW NORMAL WITH ONLY MINIMAL PCPN CHANCES.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 106 AM EDT MON APR 20 2015

LOW PRES OVER SW MI WILL LIFT N TODAY WHILE A LOW PRES TROF MOVES E
AND MERGES WITH THE LOW. THESE 2 FEATURES WILL SPREAD SHRA ACROSS
THE AREA OVERNIGHT...BRINGING DETERIORATING CONDITIONS.

SFC TROF HAS ALREADY PASSED KIWD. WITH RAIN OVER THE COLD LAKE
WATERS AND AN UPSLOPE NW WIND...LIFR CONDITIONS WILL LIKELY PREVAIL
THRU THE MORNING HRS. THE -SHRA WILL MIX WITH OR CHANGE TO -SHSN
AROUND MID MORNING. PCPN WILL THEN DIMINISH IN THE AFTN WITH
CONDITIONS IMPROVING TO MVFR UNDER GUSTY WNW WINDS. MIGHT EVEN SEE A
PERIOD OF VFR CONDITIONS. ANOTHER DISTURBANCE MAY BRING
DETERIORATING CONDITIONS AGAIN LATE THIS EVENING.

AT KCMX...WITH MAIN AREA OF PCPN AND SFC TROF NOT ARRIVING UNTIL
AROUND DAYBREAK...VFR CONDITIONS SHOULD PREVAIL UNTIL AROUND 10Z.
EXPECT A QUICK DROP TO LIFR DURING THE MORNING UNDER INCREASING
UPSLOPE NW WINDS...THEN ONLY GRADUAL IMPROVEMENT TO IFR IN THE AFTN
AS -SHRA CONTINUE. NW WIND WILL LIKELY GUST TO AROUND 30KT DURING
THE AFTN.

AT KSAW...UNTIL ARRIVAL OF SHRA FROM THE S...VFR CONDITIONS WILL
PREVAIL FOR THE NEXT FEW HRS. ARRIVAL OF SHRA AND WINDS BACKING
AROUND TO AN UPSLOPE NE TO N DIRECTION OFF LAKE SUPERIOR WILL RESULT
IN CONDITIONS QUICKLY FALLING TO LIFR BEFORE 12Z. AS WINDS BACK TO
THE NW AND THEN W IN THE AFTN AND PCPN DIMINISHES...EXPECT
IMPROVEMENT TO MVFR. MIGHT EVEN SEE A PERIOD OF VFR LATE AFTN/EARLY
EVENING.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 316 AM EDT MON APR 20 2015

AS A LOW LIFTS THROUGH THE SOO THIS AFTERNOON...WINDS WILL BACK TO
THE WEST-NORTHWEST THIS AFTERNOON. WITH THE LOW BECOMING STATIONARY
JUST TO THE SOUTHWEST OF JAMES BAY TONIGHT THROUGH
WEDNESDAY...PERSISTENT NORTHWESTERLY WINDS OF 20-30KTS ARE EXPECTED.
ALTHOUGH THE LOW WILL WEAKEN AND MOVE EAST ACROSS QUEBEC WEDNESDAY
NIGHT INTO THURSDAY...THE NORTHWEST WINDS UP TO 25KTS WILL PERSIST
AS A RIDGE MOVES INTO THE NORTHERN PLAINS. THE WINDS DIMINISH THEN
BELOW 20 KNOTS BY THURSDAY NIGHT.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...07
LONG TERM...JLB
AVIATION...ROLFSON
MARINE...07



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