Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 220930
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
430 AM EST MON DEC 22 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 425 AM EST MON DEC 22 2014

12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SW FLOW ALOFT OVER
THE WRN GREAT LKS TO THE E OF A DEEPENING UPR TROF IN THE CENTRAL
CONUS CAUSED BY SHRTWVS DIGGING SEWD IN NW FLOW ALOFT E OF UPR RDG
ALONG THE W COAST. SHRTWV RESPONSIBLE FOR THE SN ON SUN EVNG IS
LIFTING NEWD THRU NW ONTARIO. AS THE ACCOMPANYING STRONGER DYNAMIC
FORCING SHIFTS TO THE NE...IR STLT IMAGERY SHOWS WARMING CLD TOP
TEMPS AS THE COMMA TAIL MSTR BAND SHIFTS TO THE E. ALTHOUGH RADAR
SHOWS THE HEAVIER PCPN IS FOLLOWING OFF TO THE NE...SOME PATCHY
ECHOES REMAIN OVER MUCH OF THE CWA. COMPOSITE RADAR INDICATES
GENERALLY LIGHT MIXED PCPN STRETCHES OFF TO THE SW THRU MUCH OF THE
NW HALF OF WI...WHERE MODELS SHOW AN AXIS OF WEAKER DEEP LYR QVECTOR
CNVGC. SFC OBS INDICATE LOWER SFC DEWPTS OVER NRN LOWER MI...UPWIND
OF THE E HALF OF THE CWA.

MAIN FCST CONCERNS TODAY FOCUS ON DIMINISHING PCPN TRENDS. FOCUS FOR
TNGT SHIFTS TO TIMING THE ARRIVAL OF ANOTHER AREA OF SN/MIXED PCPN
AS ANOTHER SHRTWV LIFTS NEWD OUT OF DEEPENING UPR TROF THAT CAUSES A
CLOSED H5 LO TO DEVELOP IN THE CENTRAL PLAINS.

TODAY...EXPECT SOME GENERALLY LGT SN/MIXED WITH RA TO IMPACT MAINLY
THE W HALF OF THE CWA THRU THIS MRNG AWAY FM THE DRIER NEAR SFC AIR
ADVECTING INTO THE ERN ZNS AND UNDER LINGERING BUT SLOWLY FADING
DEEP LYR QVECTOR CNVGC AS SHRTWV RDG APRCHS FM THE SW. DURING THE
AFTN...ARRIVAL OF DRIER AIR ALOFT FM THE S WITHIN THE NVA SHOULD END
ANY LINGERNING LARGE SCALE PCPN. BUT CONCERNED SOME SN GRAINS/
FREEZING DZ/DZ WL LINGER OVER MAINLY THE CENTRAL CWA WITH UPSLOPE SE
FLOW OFF LK MI. THIS POTENTIAL WL BE LIMITED BY ADVECTION OF LOWER
H95-9 SPECIFIC HUMIDITY NOW OVER NRN LOWER MI...ESPECIALLY OVER THE
E HALF AND BY LATE AFTN EVEN OVER THE CENTRAL. EXPECT TEMPS TO TOP
OUT ABOVE FREEZING EVERYWHERE...SO ANY FREEZING DZ SHOULD END BY
NOON OR SO.

TNGT...AS AREA OF SGNFT DEEP LYR QVECTOR CNVGC/DEEP ISENTROPIC
ASCENT/UPR DVGC IN ADVANCE OF SHRTWV LIFTING NE TOWARD THE GREAT LKS
OVERSPREADS THE AREA...EXPECT PCPN TO DEVELOP OVER THE SCENTRAL BY
MIDNGT AND THEN SPREAD TO OVER ALL THE KEWEENAW BY 12Z TUE. PER NCEP
PREFERENCE...TENDED TOWARD THE 00Z NAM FOR FCST DETAILS. THIS MODEL
GENERATES ABOUT 0.25 INCH OF TOTAL QPF AT MENOMINEE BY 12Z TUE.
PTYPE IS A CONCERN. WHILE THE NAM FCST SDNG FOR MENOMINEE INDICATES
MAINLY RA FOR THAT LOCATION...MODEL SDNGS/H100-85 THKNS INDICATE
AREAS AWAY FM LK MI WL SEE MAINLY SN THRU 12Z TUE. ARRIVAL OF LLVL
DRY AIR TODAY THAT WL ENHANCE NEAR SFC EVAPORATIVE COOLING AND
BACKING NEAR SFC FLOW TOWARD THE ENE THAT WL CUTOFF THE ARRIVAL OF
WARMER AIR APPEAR TO BE THE REASON THE LLVL TEMPS TREND COLD ENUF
FOR MAINLY SN EXCEPT NEAR LK MI. SN/WATER RATIOS WL BE LIMITED BY
RELATIVELY HI/THIN DGZ...SO AN INCH OR TWO OF SN WL LIKELY
ACCUMULATE BY SUNRISE OVER MUCH OF THE SE HALF OF THE CWA TO THE NW
OF THE RA/SN LINE.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 303 PM EST SUN DEC 21 2014

LONG TERM SHIFT CONTINUES TO BE BUSY THROUGHOUT...BUT IT DOES APPEAR
THAT THE WED-THU STORM IS LESS LIKELY.

A SERIES OF SHORTWAVE TROUGHS WILL MOVE INTO THE CENTRAL CONUS THIS
WEEK...INTENSIFYING AN UPPER TROUGH ALSO OVER THE CENTRAL CONUS
THROUGH MID-WEEK. BY 00Z TUE...MODELS SHOW THAT THE TROUGH HAS
STRENGTHENED TO A CLOSED LOW OVER ERN IA. A LARGE AREA OF PRECIP
WILL EXIST JUST SW OF THE CWA ALONG AND AHEAD OF A SHORTWAVE TROUGH
ROTATING AROUND THE UPPER LOW AND IN AN AREA OF UPPER LEVEL
DIFFLUENCE. LIGHT PRECIP WILL MOVE IN MON NIGHT...WITH THE HEAVIEST
PRECIP EXPECTED TUE MORNING AS YET ANOTHER SHORTWAVE ROTATES AROUND
THE LOW. MODELS VARY IN THE AMOUNT OF QPF...THE 12Z/21 GFS IS ON THE
HIGH SIDE SHOWING WIDESPREAD AMOUNTS AROUND 0.45 INCHES TUE
MORNING...THE 12Z/21 NAM IS 6 HOURS FASTER AND SHOWS SLIGHTLY LESS
QPF...AND THE 00Z/21 ECMWF SHOWS ABOUT HALF THE QPF OF THE GFS. WARM
AIR BEING PULLED FROM THE SE WILL KEEP PRECIP MOSTLY AS RAIN OVER
THE ERN CWA AND MOSTLY SNOW OVER THE WRN CWA. IN BETWEEN...VERTICAL
WET BULB TEMP PROFILES RIGHT AROUND 0C MAKES FOR A MORE DIFFICULT
PTYPE FORECAST...ESPECIALLY WITH UNCERTAINTY. COULD END UP WITH
ADVISORY LEVEL SNOWFALL...BUT UNCERTAINTY REMAINS TOO HIGH TO GET
SPECIFIC WITH SNOWFALL AMOUNTS. FOR THE REST OF TUE AND TUE
NIGHT...THE LOW OVER IA SHOULD WEAKEN AND TRAVERSE ACROSS THE
CWA...WITH ONLY MINOR PRECIP AMOUNTS DURING THIS PERIOD. TUE LOOKS
TO BE THE WARMEST DAY WITH HIGHS IN THE MID TO UPPER 30S.

THE ONLY MODEL CONTINUITY FOR THE FORMER...AND POSSIBLY COULD STILL
BE...CHRISTMAS EVE/DAY STORM IS THAT THERE HAS BEEN NO MODEL
CONTINUITY...AT LEAST OVER THE LAST FEW RUNS. MODELS DID HAVE AT
LEAST SOME DECENT CONTINUITY ABOUT 24 HOURS AGO...BUT AS IS FAIRLY
TYPICAL...ONCE THE FIRST SHORTWAVE MOVED CLOSE/INTO THE BETTER
OBSERVING NETWORK...MODELS DIVERGED FROM THEIR PREVIOUS SOLUTIONS
AND FROM OTHER MODEL SOLUTIONS. HAVE SEEN MODELS RECOVER FROM THE
SWING IN SOLUTIONS FOR SIMILAR STORMS IN THE PAST AND RETURN TO A
SOLUTION MUCH LIKE WAS SHOWED BEFORE THE MODELS SWING. THIS IS THE
CASE WITH THE NEWEST GFS (12Z/21) AS THE PREVIOUS RUN SHOWED THE
SYSTEM MUCH WEAKER AND FARTHER E...BUT THE NEW RUN SHOWS THE UPPER
TROUGH BEING SHARPER AND MORE NEGATIVELY TILTED...RESULTING IN A
CLOSED SFC LOW MOVING N TO LAKE SUPERIOR AT 987MB AT 00Z THU THEN
RAPIDLY MOVING TO ERN QUEBEC NEAR JAMES BAY AT 970MB AT 12Z THU.
WHILE THE GFS IS STILL AN OUTLIER SOLUTION...AND CONFIDENCE IS LOWER
WITH THE GFS DUE TO POOR ENSEMBLE CLUSTERING...THE SOLUTION SHOWN IS
STILL IN THE REALM OF POSSIBILITY. THE 00Z/21 ECMWF IS SIMILAR TO
THE 06Z GFS RUN IN SHOWING THE SYSTEM MUCH WEAKER AND FARTHER E.
EVEN IF THE FARTHEST W GFS VERIFIES...ONLY THE EXTREME ERN CWA WOULD
BE GRAZED BY THE GREATER SYNOPTIC PRECIP. WITH THE MORE BETTER
CONFIDENCE IN THE MORE ERN/WEAKER SOLUTION...PRECIP BEING ALL OR
MOSTLY SNOW BY WED IS FAVORED. STILL WILL SEE SOME SYNOPTIC
SNOW...BUT ONLY MINOR AMOUNTS...AS THE UPPER TROUGH SHIFTS ACROSS
THE AREA. WILL CONTINUE MONITORING CLOSELY...BUT CHANCES FOR A MAJOR
WINTER STORM APPEAR TO BE DWINDLING.

WITH 850MB TEMPS FALLING TO AROUND -8C BY THU AND W-WNW LOW LEVEL
WINDS...COULD SEE SOME LAKE ENHANCED/UPSLOPE SNOW OVER THE
W/KEWEENAW FROM WED NIGHT...WEAKENING THROUGH THE DAY THU AS THE
SYNOPTIC FORCING MOVES E. MODELS THEN BRING ANOTHER SHORTWAVE JUST
SW OF THE CWA ON FRI AHEAD OF AN UPPER TROUGH. OF COURSE...LOTS OF
UNCERTAINTY WITH THE SHORTWAVE...BUT COULD SEE SNOW FRI AS A RESULT.
LAKE EFFECT SNOW AND MUCH COLDER TEMPS ARE THE FOCUS WITH THE UPPER
TROUGH MOVING IN AS 850MB TEMPS FALL TO -20C TO -25C BY SAT MORNING
AND REMAIN OVER THE AREA INTO SUN. IF THIS OCCURS...WILL SEE A GOOD
LES EVEN IN WNW-NW WIND SNOWBELTS LATE FRI INTO AT LEAST SUN.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1236 AM EST MON DEC 22 2014

LIGHT/MODERATE SNOW CONTINUES ACROSS THE AREA UNDER A SOUTH FLOW OF
MOIST LLVL AIR WITH CONDITIONS RANGING FROM LIFR/VLIFR AT KCMX TO
MVFR AT KIWD. EXPECT IMPROVING CONDITIONS AT KCMX AND KSAW TO HIGH
END IFR LATE TONIGHT AND THEN TO MVFR LATE MON MORNING AS DRIER AIR
MOVES IN FM THE SOUTH. CONDITIONS WILL REMAIN MVFR THROUGH THE PD AT
KIWD AS DOWNSLOPE SOUTH WINDS SHOULD LIMIT LOWER CIGS AND VSBY
RESTRICTIONS.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 425 AM EST MON DEC 22 2014

SSE WINDS UP TO 25-30 KTS OVER MAINLY THE E HALF OF LK SUPERIOR WILL
PERSIST THRU TODAY BUT THEN BACK TO THE E TONIGHT AND THEN THE NE ON
TUE AS A LO PRES SYSTEM MOVES NE FROM THE CENTRAL PLAINS TO OVER
LAKE MICHIGAN BY LATE IN THE DAY ON TUE. SINCE THIS LO WILL SLOWLY
WEAKEN AS IT MOVES TO THE NE...THE NE WINDS WILL FALL UNDER 20 KTS
ON TUE NIGHT. SINCE THE LATEST GUIDANCE INDICATES THE NEXT DEEPER LO
WILL TRACK N FARTHER TO THE E ON WED...A WEAKER PRES GRADIENT/N WIND
UNDER 20 KTS WILL DOMINATE ON WED. YET ANOTHER LO PRES MAY MOVE NE
FROM THE CENTRAL PLAINS LATE IN THE WEEK. AT THIS TIME...WINDS UNDER
25 KTS ARE EXPECTED.
&&

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

$$

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



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