Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 310913
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
513 AM EDT FRI OCT 31 2014

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 424 PM EDT THU OCT 30 2014

WV IMAGERY AND RUC ANALYSIS INDICATED A STRONG SHORTWAVE TROUGH OVER
NW ONTARIO(N OF KINL) DIVING TO THE SE TOWARD WRN LAKE SUPERIOR. THE
SHRTWV SUPPORTED SCT/NMRS RAIN SHOWERS OVER NE MN AND SOME SNOW
SHOWERS OVER FAR NRN MN AND ADJOINING PORTIONS OF ONTARIO WHERE
VISIBILIITES HAD DROPPED AOB 1SM. A WEAK SHRTWV THROUGH CNTRL UPPER
MI ALSO WAS BRINGING SOME SCT LIGHT RAIN SHOWERS THROUGH NRN UPPER
MI. STRONG NRLY WINDS HAVE DEVELOPED INTO NRN MN BETWEEN 1015MB LOW
PRES OVER CNTRL UPPE R MI AND A 1036 MB HIGH OVER SASK INTO WRN
MANITOBA. WINDS WERE GUSTING INTO THE 30-35 KNOT RANGE INTO NW MN
WITH THE PRES RISE ASSOCIATED WITH THE FRONT/TROUGH.

TONIGHT...EXPECT THE PCPN COVERAGE TO INCREASE THIS EVENING FROM
WEST TO EAST AS THE ONTARIO SHRTWV MOVES INTO THE AREA. WET-BULB
ZERO HEIGHTS AND UPSTREAM OBS SUGGEST THAT THE RAIN WILL QUICKLY
CHANGE OVER TO SNOW THIS EVENING AS THE COLDER AIR MOVES IN BEHIND
THE COLD FRONT. THE COMBINATION OF STRONG 700-300 MB QVECTOR
CONV...850 MB TEMPS DROPPING INTO THE -8C TO -10C RANGE BY 06Z AND
TO -12C BY 12Z (LAKE WATER TEMPS NEAR 7C) AND STRONG CYCLONIC NRLY
WINDS WILL RESULT IN A PERIOD OF MODERATE TO BRIEFLY HEAVY LAKE
ENHANCED SNOW...MAINLY BTWN 03Z-09Z. ALTHOUGH SLR VALUES INTO THE
10/1-15/1 RANGE ARE EXPECTED ALONG WITH QPF IN THE 0.25 TO 0.50 INCH
RANGE...THERE IS LINGERING UNCERTAINTY WITH HOW MUCH SNOW WILL
ACCUMULATE OVER THE WARMER GROUND AND ROAD SURFACES THAT WERE STILL
NEAR 40F. LOCATIONS FAVORED BY THE STRONG UPSLOPE
FLOW IN WEST AND N CNTRL UPPER WILL SEE THE GREATEST SNOWFALL RATES
WITH ACCUMULATIONS IN THE 2 TO 4 INCH RANGE WEST AND POSSIBLY 3 TO 6
INCHES N CNTRL. A LATER CHANGEVER TO SNOW AND GREATER MARINE
INFLUENCE WILL LIMIT ACCUMULATIONS CLOSER TO THE SHORE TO AN INCH OR
TWO. OVER THE SOUTH...ACCUMULATIONS AROUND AN INCH ARE ALSO POSSIBLE.

GUSTY WINDS INTO THE 30 TO 40 MPH RANGE WILL ALSO DEVELOP AS THE
STRONG ISALLOBARIC WIND COMPONENT MOVES THROUGH BTWN 03Z-09Z WITH A
FST 5 MB 3 HOUR PRES RISE AND A VERY TIGHT GRADIENT DEVELOPS TOWARD
DAYBREAK. THE COMBINATION OF THE WINDS AND WAVES MAY LEAD TO SOME
MINOR LAKESHORE FLOODING.

FRIDAY...EXPECT THE SNOWFALL INTENSITY TO DIMINISH DURING THE
MORNING AS STRONG QVECTOR DIV AND SUBSIDENCE TAKE OVER WITH
INVERSION HEIGHTS FALLING TO AROUND 5K FT. IN ADDITION MORE ACYC
FLOW MOVES INTO THE WEST AS THE SFC RIDGE APPROACHES.
HOWEVER...INSTABILITY OVER THE LAKE COMBINED WITH THE UPSLOPE FLOW
WILL KEEP LES GOING THROUGH MUCH OF THE DAY ESPECIALLY OVER THE
HIGHER TERRAIN IN N CNTRL UPPER WITH LOWER AMOUNTS OF ONLY AN INCH
OR TWO. TEMPS WILL STRUGGLE INTO THE LOWER 30S.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 512 AM EDT FRI OCT 31 2014

AN INITIALLY AMPLIFIED PATTERN ACROSS NAMERICA...FEATURING A SHARP
CNTRL RIDGE AND DEEP ERN TROF...WILL DEAMPLIFY/BECOME MORE
PROGRESSIVE DURING THE LONG TERM. SOME AMPLIFICATION WILL OCCUR
AGAIN LATER NEXT WEEK AS AN ERN TROF REDEVELOPS...BUT PATTERN WILL
REMAIN PROGRESSIVE. THIS PATTERN EVOLUTION WILL MEAN BLO NORMAL
TEMPS INITIALLY WILL TRANSITION TO NORMAL TO ABOVE EARLY NEXT WEEK.
THERE WILL THEN BE A TREND BACK TO NEAR/BLO NORMAL TEMPS LATER NEXT
WEEK AS ERN TROF REDEVELOPS. AS FOR PCPN...AFTER DRY WEATHER OVER
THE WEEKEND...PCPN CHANCES WILL RETURN EARLY NEXT WEEK IN RESPONSE
TO ONE SHORTWAVE TROF SHIFTING ACROSS THE GREAT LAKES REGION AND
THEN A FOLLOWING SHORTWAVE TROF PASSING AROUND THE MIDWEEK PERIOD
THAT LEADS INTO THE ERN TROF AMPLIFICATION. LOOKING FARTHER AHEAD...
THE FIRST REALLY COLD AIR MASS OF THE SEASON FOR N AMERICA WILL BE
DEVELOPING IN NCNTRL CANADA IN THE 7-10 DAY TIME FRAME AS A POSITIVE
ANOMALY DEVELOPS IN THE VCNTY OF AK/NW CANADA AND THE ADJACENT
ARCTIC OCEAN. AT LOWER LATITUDES...A GENERAL ZONAL FLOW IS FCST
ACROSS THE CONUS...SO IT DOESN`T LOOK LIKE THIS COLD AIR WILL DUMP S
ANYTIME SOON. IN FACT...CFSV2 RUNS ARE INDICATING THAT ABOVE NORMAL
TEMPS WILL GENERALLY PREVAIL THRU EARLY AND MID NOV...AND THERE IS
SOME INDICATION FOR AN ABOVE NORMAL PCPN PATTERN TO DEVELOP AS WELL.

BEGINNING SAT...EXPECT MOSUNNY WX AS PRONOUNCED MID/UPPER RIDGE
DRIFTS ACROSS THE CNTRL CONUS WITH ASSOCIATED SFC HIGH PRES RIDGE
SHIFTING FROM WRN UPPER MI IN THE MORNING TO ERN UPPER MI BY
EVENING. ALTHOUGH SOME HIGH CLOUDS WILL SPREAD DOWNSTREAM OF THE
MID/UPPER RIDGE AXIS AND INTO THE UPPER LAKES...THICKER CLOUDS
SHOULD HOLD OFF UNTIL EVENING. UNDER A GOOD DISPLAY OF SUNSHINE AND
DEVELOPING RETURN SLY FLOW ON THE BACKSIDE OF SFC RIDGE...TEMPS OVER
THE W WILL REBOUND ABOVE 40F AFTER A VERY COLD START TO THE DAY.
TEMPS OVER THE E WON`T GET OUT OF THE 30S AS RETURN FLOW REALLY
DOESN`T GET UNDERWAY UNTIL EVENING.

HIGH AND MID CLOUDS WILL THICKEN SOME SAT NIGHT UNDER STRENGTHENING
WAA/ISENTROPIC ASCENT. AT THIS TIME...IT APPEARS AIR MASS WILL BE
MUCH TOO DRY AT LOWER LEVELS TO SUPPORT ANY PCPN. COMBINATION OF
INCREASING SOUTHERLY FLOW ON THE WRN FLANK OF DEPARTING SFC RIDGE
AND THICKER CLOUDS WILL WORK TO LIMIT THE DIURNAL TEMP FALL. THE
LOWEST TEMPS TOWARD 20F WILL OCCUR OVER THE INTERIOR E AS THERE WILL
BE LIGHT/CALM WINDS IN THE EVENING...CLOSER TO THE DEPARTING RIDGE.
DOWNSLOPE AREAS NEAR LAKE SUPERIOR WILL SEE HIGHER TEMPS AOA 30F.
UNDER SOME HIGH/MID CLOUDS...TEMPS ON SUN SHOULD RISE INTO THE 40S
EVERYWHERE WITH MIXING TO 900-875MB. HOWEVER...GUSTY S WINDS UNDER
SHARPENING PRES GRADIENT BTWN DEPARTING RIDGE AND LOW PRES TROF
MOVING OUT OVER THE PLAINS WILL MAKE THE DAY FEEL COOLER. ALTHOUGH
WAA/ISENTROPIC ASCENT CONTINUES...LOW-LEVELS REMAIN TOO DRY TO
SUPPORT ANY PCPN CONCERN.

ONE SHORTWAVE WILL SHIFT OUT OVER THE NRN PLAINS SUN NIGHT WHILE
ANOTHER MOVES INTO THE SRN ROCKIES. AHEAD OF THESE SHORTWAVES...SW
FLOW WILL CONTINUE THRU THE CNTRL CONUS INTO THE GREAT LAKES.
DESPITE THE CONTINUED SW FLOW...MOISTENING OF THE LOW-LEVELS REMAINS
SLOW PER FCST SOUNDINGS. COMBINED WITH THE LACK OF MEANINGFUL
FORCING...SUN NIGHT WILL REMAIN DRY. MIN TEMPS SHOULD BE MOSTLY IN
THE 30S.

MON THRU TUE NIGHT...NRN SHORTWAVE WILL PROGRESS DOWNSTREAM FASTER
THAN THE SRN WAVE. AS A RESULT...THE MAIN TAP OF GULF MOISTURE WILL
LIKELY GET SHUNTED E BEFORE REACHING THE UPPER LAKES. THUS...AS COLD
FRONT SWEEPS ACROSS THE AREA MON NIGHT...MEDIUM RANGE MODELS ARE IN
FAIRLY GOOD AGREEMENT INDICATING THAT THE NORTHEASTWARD DEVELOPING
RIBBON OF PCPN WILL PASS MOSTLY E OF THE FCST AREA MON NIGHT AND TUE
MORNING. SO...BEST CHC OF PCPN SHOULD BE OVER ERN PORTIONS OF THE
FCST AREA. HOWEVER...FORCING FROM UPPER JET STREAK MAY WORK TO
SPREAD/DEVELOP PCPN BACK BEHIND THE COLD FRONT TUE. IN THE END...
THIS MAY RESULT IN THE BEST CHC OF PCPN OCCURRING AT THAT TIME. WITH
850MB TEMPS FALLING TO -3 TO -5C BEHIND FRONT...SOME SNOW MAY MIX
WITH ANY LINGERING -SHRA OVER THE FAR W LATE MON NIGHT/TUE MORNING.

WED/THU...A CLIPPER-TYPE SHORTWAVE IS FCST TO TRACK SE THRU THE
GREAT LAKES. SINCE SPREAD IN THE MODEL SOLUTIONS ON TRACK/INTENSITY
OF THE WAVE IS RATHER SIGNIFICANT...DIDN`T DEVIATE MUCH FROM
CONSENSUS FCST. SOME LIGHT RAIN AND SNOW WILL BE POSSIBLE.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1134 PM EDT THU OCT 30 2014

FIRST WIDESPREAD WINTER EVENT OF THE SEASON HAS BEGUN...AS LOW
PRESSURE EXITING ACROSS LOWER MI AND LAKE HURON THIS MORNING USHERS
IN MUCH COOLER MOIST AIR FROM THE NORTH. ALL 3 TAF SITES TURNED OVER
TO ALL SNOW BY 0230Z. THE STRONGEST PART OF THE SYSTEM SNOW WISE
WILL EXIT E BY 10Z...WITH SLOWLY IMPROVING CONDITIONS.
HOWEVER...FAVORABLE N UPSLOPE FLOW AT SAW WILL KEEP LAKE EFFECT SNOW
GOING THROUGH THE DAY FRIDAY. OTHER THAN LOWER CEILINGS HOVERING
AROUND IFR-MVFR...BLOWING SNOW FROM STRONG WINDS WILL BE THE MAIN
THREAT...REDUCING VIS TO AROUND 1SM OR LESS AT TIMES /PRIMARILY
BEFORE 09Z/. GUSTY N WINDS WILL DIMINISH TO LESS THAN 20KTS AFTER
18Z FRIDAY...WHILE STILL GUSTING IN THE 25KT RANGE AT SAW THROUGH
LATE AFTERNOON. AS DRIER HIGH PRESSURE ROLLS IN FROM THE W...DRIER
AIR WILL PUSH IN WITH VFR CEILINGS RETURNING BY MID AFTERNOON AT IWD
AND CMX...AND BY 06Z SATURDAY AT SAW.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 342 PM EDT THU OCT 30 2014

EXPECT N TO NW GALES TO 35-45 KTS TO DEVELOP OVER LAKE SUPERIOR
TONIGHT AS A STRONG DISTURBANCE SHIFTS SE THROUGH THE UPPER LAKES
AND THE PRES GRADIENT SHARPENS BETWEEN ACCOMPANYING LO PRES OVER
LOWER MI AND HI PRES IN THE NORTHERN PLAINS. STRONG SURGE OF COLD
AIR ACROSS THE RELATIVELY WARM LAKE WATERS WILL DESTABILIZE THE
LOWER LEVELS AND ENHANCE MIXING OF STRONGER N WINDS TO THE LAKE
SURFACE. THESE WINDS WILL THEN DIMINISH W-E LATE FRI INTO SAT AS THE
HI PRES RIDGE/WEAKER GRADIENT OVERSPREAD THE LAKE W-E. ONCE THE HI
SHIFTS TO THE E AND THE PRES GRADIENT SHARPENS AGAIN TO THE E OF LO
PRES DEVELOPING IN THE NORTHERN PLAINS...LOOK FOR S WINDS UP TO
20-25 KTS TO DEVELOP AND PERSIST INTO MON. AS THE LO SHIFTS ACROSS
ONTARIO LATER ON MON INTO TUE...A COLD FRONT WILL PASS OVER LAKE
SUPERIOR...WITH WINDS VEERING TO THE W-NW UP TO 25 KTS ON TUE IN ITS
WAKE.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
  LAKE EFFECT SNOW ADVISORY UNTIL NOON EDT /11 AM CDT/ TODAY FOR
     MIZ001>003-009-084.

  LAKESHORE FLOOD ADVISORY UNTIL 2 PM EDT /1 PM CDT/ THIS
     AFTERNOON FOR MIZ001>006-009.

  LAKE EFFECT SNOW ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR
     MIZ004>006.

LAKE SUPERIOR...
  GALE WARNING UNTIL 2 PM EDT THIS AFTERNOON FOR LSZ249>251-266-
     267.

  GALE WARNING UNTIL NOON EDT TODAY FOR LSZ248-265.

  GALE WARNING UNTIL 11 AM EDT THIS MORNING FOR LSZ243>247-264.

  GALE WARNING UNTIL 8 AM EDT /7 AM CDT/ THIS MORNING FOR LSZ162-
     240>242-263.

LAKE MICHIGAN...
  GALE WARNING UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ221-248-250.

&&

$$

SHORT TERM...JLB
LONG TERM...ROLFSON
AVIATION...KF
MARINE...KC






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