Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 290927
AFDMQT

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

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 524 AM EDT SUN MAR 29 2015

WV IMAGERY AND RUC ANALYSIS INDICATED A WELL A VIGOROUS WELL-DEFINED
SHORTWAVE TROUGH OVER THE DAKOTAS MOVING TOWARD THE WRN GREAT LAKES
AS THE MID/UPPER LEVEL PATTERN BECOMES MORE ZONAL. THE SHRTWV
SUPPORTED AN AREA OF RAIN ACROSS NW INTO ERNL MN. SOME TSRA HAD ALSO
DEVELOPED NEAR MSP AT THE NOSE OF A STRONG SRLY LOW LEVEL JET. AT
THE SFC...A 996 TROUGH EXTENDED ACROSS NORTHWEST ONTARIO INTO THE NW
CORNER OF MN. BRISK SRLY WINDS AND WAA PREVAILED FROM THE UPPER MS
VALLEY INTO THE WRN LAKES IN THE TIGHT PRES GRADIENT BETWEEN THE
TROUGH AND A 1030 MB HIGH OVER THE ERN OH VALLEY.

TODAY INTO THIS EVENING...300K-305K ISENTROPIC LIFT WITH THE
INTITIAL BAND OF PCPN AND 700-300 MB QVECTOR CONV AHEAD OF THE
SHRTWV WILL BE STRONG ENOUGH TO PRODUCE QPF AMOUNTS IN THE 0.15-0.40
INCH RANGE WITH THE GREATEST AMOUNTS OVER THE ERN CWA. ALTHOUGH THE
UPSTREAM PCPN IS MAINLY RAIN...FCST SOUNDINGS WET-BULB ZERO HEIGHTS
SUGGEST THAT THE PCPN SHOULD CHANGE OVER TO MAINLY SNOW OVER UPPER
MICHIGAN. THERE MAY BE A PERIOD OF RAIN OR SLEET UNTIL THE PCPN
INTENSITY IS GREAT ENOUGH TO LOWER 900-750 MB TEMPS BELOW FREEZING.
A QUICK INCH OR TWO WILL BE POSSIBLE OVER MUCH OF UPPER MICHIGAN
WITH SLIGHTLY GREATER AMOUNTS OF 3 TO 5 INCH POSSIBLE EAST OF ISQ-
SENEY WHERE THE WINTER WX ADVY REMAINS IN EFFECT. AS THE PCPN
INTENSITY DIMINISHES AND LOW LEVEL TEMPS CLIMB...THE LIGHTER PCPN BY
MID AFTERNOON SHOULD CHANGE OVER TO RAIN OR DRIZZLE OVER THE WEST
HALF.

IN ADDITION...GUSTY SSW WINDS ARE EXPECTED THIS MORNING AHEAD OF THE
TROUGH. EVEN THOUGH A 900 MB LOW LEVEL JET OVER AOA 60 KT IS FCST
DURING THE MORNING...LOW LEVEL STABILITY WILL BE STRONG ENOUGH SO
THAT MIXING TOWARD THE SFC RESULTS IN MORE MODERATE GUSTS IN THE 25-
30 MPH RANGE. HOWEVER...LOCATIONS NEAR THE LAKE MICHIGAN SHORELINE
MAY SEE GUSTS TO AROUND 40 MPH. A PERIOD OF GUSTY WRLY WINDS WILL
ALSO BE POSSIBLE DURING THE LATE AFTERNOON AND EVENING...ESPECIALLY
OVER THE HIGHER TERRAIN OF THE KEWEENAW...AS THE STRONGER
ISALLOBARIC COMPONENT MOVES THROUGH BEHIND THE TROUGH. WINDS VEERING
TO THE NW WILL ALSO BRING GUSTY WINDS TO 40 MPH NEAR LAKE SUPERIOR E
OF MARQUETTE BTWN 02Z-06Z.

LATE THIS EVENING AND OVERNIGHT...SOME ADDITIONAL LIGHT SNOW/RAIN
SHOWERS MAY BE POSSIBLE IN THE MOIST CYCLONIC NW FLOW AROUND THE
DEPARTING LOW AS A TRAILING SHORTWAVE MOVES THROUGH DURING THE
EVENING...ESPECIALLY IN NW UPSLOPE FLOW LOCATIONS. EXPECT LIGHT SNOW
SHOWERS TO DIMINISH OVERNIGHT AS THE DEEPER MOISTURE DEPARTS TO THE
EAST.

.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 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 524 AM EDT SUN MAR 29 2015

SOUTH SOUTHWEST GALES THIS MORNING VEERING TO WEST AND NORTHWEST
GALES LATE TODAY AND TONIGHT ARE EXPECTED AS A STRONG TROUGH AND
UPPER LEVEL DISTURBANCE MOVE THROUGH THE NRN LAKES. A 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 UNTIL 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...JLB
LONG TERM...TITUS
AVIATION...KC
MARINE...JLB



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