Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 290812
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
412 AM EDT SUN MAR 29 2015

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 337 PM EDT SAT MAR 28 2015

UPPER AIR PATTERN CONSISTS OF A DEEP 500 MB TROUGH OVER THE ERN U.S.
THIS MORNING WITH A SHORTWAVE RIDGE ACROSS THE ROCKIES AND A
SHORTWAVE IN THE PACIFIC NW. THIS RIDGE MOVES INTO THE UPPER GREAT
LAKES TONIGHT WHILE THE SHORTWAVE MOVES INTO THE NORTHERN PLAINS AND
THEN THE SHORTWAVE MOVES THROUGH THE UPPER GREAT LAKES ON SUN.

NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE TONIGHT WITH
DEEPER MOISTURE COMING IN LATE TONIGHT. THE MOISTURE STARTS TO HEAD
OUT LATE SUN AFTERNOON WITH Q-VECTOR DIVERGENCE MOVING IN BY SUN
EVENING. GFS AND ECMWF SHOW ABOUT THE SAME THING AS WELL.

QUIET FORECAST FOR TONIGHT AS PCPN HOLDS OFF UNTIL SUNDAY AND THEN
FORECAST BECOMES COMPLICATED IN A HURRY. WILL HAVE VERY DRY AIR
ALOFT TO WORK THROUGH FIRST AND HELD OFF ON THE PCPN UNTIL 12Z
SUNDAY OVER THE WEST AND INCREASED POPS  SUNDAY MORNING TO
CATEGORICAL. LOOKED AT NUMEROUS SOUNDINGS FOR MIXED PCPN AND LOOKED
TO ME LIKE THE MAJORITY OF THE PCPN WOULD STAY AS SNOW ESPECIALLY
ACROSS THE EAST HALF OF THE CWA AS WET BULB ZERO HEIGHTS STAY LOW
WITH PLENTY OF EVAPORATION TO COOL THE SOUNDINGS ALL BELOW ZERO.
EVEN IF THERE IS SOME WARM AIR ALOFT WHICH THE NAM IS THE MOST
AGGRESSIVE WITH...FEELING IS THAT WITH THE DRY AIR TONIGHT...WOULD
COOL THIS BACK BELOW WET BULB ZERO.

THE WARM AIR TRIES TO MAKE IT INTO THE WEST IN THE AFTERNOON...BUT
BY THAT TIME...THE DEEPER MOISTURE IS MOVING OUT AND THERE COULD BE
A RAIN/SNOW MIX IN THE WEST IN THE AFTERNOON. OVER THE EAST...THE
PCPN WILL STAY AS ALL SNOW AND COULD SEE A QUICK 3-6 INCHES OF SNOW
OVER SCHOOLCRAFT AND LUCE COUNTIES AND FOR THAT REASON WENT WITH A
WINTER WEATHER ADVISORY FOR THEM FROM LATE SUNDAY MORNING INTO
SUNDAY EVENING. TOTAL QPF FOR THIS EVENT LOOKS TO BE FROM 0.20 TO
0.35 INCH WITH SNOW RATIOS FAIRLY LOW IN A WET AND HEAVY SNOW. FOR
TEMPERATURES...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST.
USED A NON DUIRNAL TEMPERATURE CURVE FOR TONIGHT WITH LOWS SHORTLY
AFTER MIDNIGHT...THEN TEMPS SLOWLY WARMING AND HIGHS ON SUNDAY WILL
BE LATE IN THE DAY.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 411 AM EDT SUN MAR 29 2015

SYNOPTIC PRECIP ASSOCIATED WITH THE SYSTEM THAT WILL MOVE THROUGH
TODAY WILL BE E OF THE CWA BY 12Z MON. THERMAL TROUGH OVER THE CWA
WILL ALLOW FOR SOME LIGHT SNOW SHOWERS ON MON...BUT DRY AIR WILL
KEEP THOSE ISOLATED TO SCATTERED. LOTS OF UNCERTAINTY WITH DETAILS
OF A SHORTWAVE THAT LOOKS TO MOVE NEARBY LATE MON/MON NIGHT. MODELS
VARY IN TIMING...STRENGTH AND TRACK OF THE SHORTWAVE AND ASSOCIATED
SFC LOW...AND EVEN SMALL DIFFERENCES IN THESE CHARACTERISTICS MAKES
FOR SIGNIFICANT FORECAST DIFFERENCES. THE 00Z/29 NAM IS ON THE
FASTER...STRONGER AND FARTHER N END OF GUIDANCE...WHICH MEANS
GREATER QPF AMOUNTS BUT ALSO MORE MIXED PRECIP. ON THE OTHER
HAND...THE 00Z/29 ECMWF IS WEAKER AND ON THE SRN SIDE OF
GUIDANCE...MEANING ONLY MINOR PRECIP AMOUNTS. CERTAINLY POTENTIAL
FOR ADVISORY LEVEL SNOWFALL IN A NARROW BAND...BUT NOT AT ALL
CONFIDENT WITH WHERE...EXACTLY WHEN AND AMOUNT OF SNOW.

SHOULD BE ABLE TO SEE SOME LIGHT SNOW SHOWERS IN NLY FLOW OF LAKE
SUPERIOR ON TUE...MAINLY OVER NCENTRAL UPPER MI...BUT ONLY MINOR
AMOUNTS.

MAJOR CHANGES COMING ON WED AS A STRONGER SYSTEM MARCHES ALONG THE
US/CANADIAN BORDER...PULLING PLENTY OF WARMER AIR N INTO THE CWA.
850MB TEMPS INCREASE TO AROUND 10C AHEAD OF A SFC TROUGH/COLD FRONT
THAT WILL MOVE THROUGH LATE WED THROUGH WED NIGHT. RAIN WILL BE
POSSIBLE IN THE WAA REGIME AHEAD OF THE COLD FRONT AND ALSO ALONG
THE COLD FRONT. WINDS WILL ALSO BE AN ISSUE AS S-SW 925MB WINDS
INCREASE UP TO 50KTS JUST AHEAD OF THE COLD FRONT...CREATING GUSTY
SFC WINDS. SHOULD BE ABLE TO GET HIGH TEMPS INTO THE 50S OVER THE W
HALF AND IN THE 40S OVER THE E HALF DOWN WIND OF LAKE MICHIGAN. LOW
WED NIGHT WILL BE IN THE 30S TO AROUND 40. RAIN...WARMER
TEMPS...GREATER LOW LEVEL MOISTURE AND WINDS WILL MAKE FOR INCREASED
SNOWPACK MELTING WED/WED NIGHT...BUT NO FLOODING ISSUES ARE
ANTICIPATED AS RIVERS/STREAMS ARE NOT ELEVATED.

THU THROUGH SAT IS VERY UNCERTAIN AS MODELS ARE ALL OVER THE PLACE
WITH SOLUTIONS. THE ECMWF WAIT TO MOVE COLDER AIR IN UNTIL A
SIGNIFICANT SYSTEM MOVES WELL SE OF THE AREA FRI. THE GFS BRINGS A
MUCH COLDER AIRMASS IN ON THU WITH SOME TEMP MODERATE ON SAT AND NO
SIGNIFICANT SYSTEMS. WILL LEAN HEAVILY ON CONSENSUS GUIDANCE THU
THROUGH SAT.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 120 AM EDT SUN MAR 29 2015

STRONG S WINDS ABOVE A SHALLOW INVRN CAUSED BY NOCTURNAL COOLING AND
UNDER THE TIGHTENING PRES GRADIENT BTWN SFC HI PRES OVER THE MID
ATLANTIC STATES/LO PRES IN SCENTRAL CANADA SLIDING SE TOWARD THE UPR
LKS WL CAUSE LLWS AT ALL THE TAF SITES EARLY THIS MRNG. WITH
LINGERING LLVL DRY AIR...VFR CONDITIONS WL PERSIST DESPITE INCRSG HI
CLDS. AS THE LO MOVES THRU ONTARIO TODAY...SOME MIXED PCPN...MAINLY
SN...WL OVERSPREAD UPR MI. THE BEST CHC FOR ACCOMPANYING LOWER IFR
CONDITIONS FOR AT LEAST A COUPLE OF HRS WL BE AT CMX AND SAW...
WHICH WL BE CLOSER TO THE SHARPER DYNAMIC FORCING ASSOCIATED WITH
THE LO. IWD WL ALSO BE IMPACTED BY A STRONGER DOWNSLOPE SSW WIND
COMPONENT THAT WL LOWER THE CHC FOR IFR CONDITIONS. THE ONSET OF THE
PCPN WL CAUSE THE STRONG WINDS ALOFT TO REACH THE SFC...WITH WIND
GUSTS AS HI AS 25-30KTS DVLPG AFTER SUNRISE. LOOK FOR THE PCPN TO
DIMINISH BY MID/LATE AFTN WITH THE ARRIVAL OF LARGER SCALE
SUBSIDENCE AND THE PASSAGE OF A COLD FNT...ALLOWING CONDITIONS TO
IMPROVE. BUT GUSTY WNW WINDS WL ALSO FOLLOW THE FROPA AS THE LLVL
INSTABILITY INCREASES. THE ARRIVAL OF DRIER LLVL AIR WL CAUSE A
GRADUAL IMPROVEMENT TO VFR BY LATE IN THE TAF PERIOD...WITH THE
UPSLOPE NATURE OF THESE STRONG WINDS AT IWD AND ESPECIALLY CMX
SLOWING THIS PROGRESSION AT THOSE SITES.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 337 PM EDT SAT MAR 28 2015

STRONG SOUTHWEST WINDS EXPECTED LATE TONIGHT THROUGH SUNDAY NIGHT AS
LOW PRESSURE SYSTEM CROSSES MANITOBA AND NORTHERN ONTARIO. SOUTHWEST
GALES POSSIBLE WITH THIS SYSTEM ON SUN...ESPECIALLY ON THE EAST
HALF. NORTHWEST GALES POSSIBLE SUNDAY NIGHT INTO MONDAY IN WAKE OF
THE LOW PRESSURE SYSTEM AND TROUGH. SERIES OF LOW PRESSURE TROUGHS
CROSS LAKE SUPERIOR THROUGH THE REST OF NEXT WEEK...BUT WINDS ARE
EXPECTED TO STAY MAINLY BELOW 20 KTS.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
  WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO 11 PM EDT
     THIS EVENING FOR MIZ007-014-085.

LAKE SUPERIOR...
  GALE WARNING FROM 8 AM THIS MORNING TO 5 AM EDT MONDAY FOR
     LSZ249>251-266-267.

  GALE WARNING UNTIL 11 AM EDT /10 AM CDT/ THIS MORNING FOR LSZ162-
     263.

  GALE WARNING FROM 5 PM THIS AFTERNOON TO 2 AM EDT MONDAY FOR
     LSZ264-265.

LAKE MICHIGAN...
  GALE WARNING UNTIL 8 PM EDT THIS EVENING FOR LMZ221-248-250.

&&

$$

SHORT TERM...07
LONG TERM...TITUS
AVIATION...KC
MARINE...07



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