Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 251948
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
248 PM EST THU DEC 25 2014

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 248 PM EST THU DEC 25 2014

A FAIRLY QUIET WEATHER PATTERN OVER THE UPPER GREAT LAKES REGION
FOR THE SHORT TERM FORECAST...WITH JUST SOME LIGHT SNOW POSSIBLE
OVER WESTERN/CENTRAL UPPER MICHIGAN TONIGHT INTO FRIDAY. A SURFACE
RIDGE HAS BEEN SHIFTING ACROSS UPPER MICHIGAN TODAY...BUT WITH
ABUNDANT MOISTURE BELOW THE SUBSIDENCE INVERSION AROUND 850MB ON
THE 12Z KGRB SOUNDING...MUCH OF THE CWA HAS SEEN LOW CLOUDS TODAY.
THERE IS AN EXCEPTION TO THE LOW CLOUDS...GENERALLY OVER CENTRAL
UPPER MICHIGAN WHERE THESE LOW CLOUDS HAVE SCATTERED OUT AND LEAVE
MID CLOUDS. THAT SCATTERING OUT WAS AIDED BY THE INCREASING
SOUTHWESTERLY FLOW AHEAD OF THE ELONGATED SURFACE TROUGH STRETCHING
FROM NORTHERN ONTARIO THROUGH MINNESOTA AND TO A LOW IN EASTERN
COLORADO. THIS TROUGH...ALONG WITH PIECES OF SHORTWAVE ENERGY SEEN
ON WATER VAPOR IMAGERY THIS AFTERNOON LIFTING NORTHEAST OUT OF
COLORADO...WILL BE THE PRIMARY FOCUS FOR THE FORECAST.

INITIAL VERY WEAK SHORTWAVE OVER MINNESOTA AND WEST CENTRAL
WISCONSIN WILL SHIFT NORTHEAST ACROSS CENTRAL/EASTERN UPPER
MICHIGAN THIS EVENING. THERE HAS BEEN PRECIPITATION ASSOCIATED WITH
THIS WAVE IN EASTERN SOUTH DAKOTA AND MINNESOTA EARLIER TODAY (TIED
IN WITH THE 800-600MB FGEN IN THAT AREA) AND IT HAS BEEN SPREADING
INTO WEST CENTRAL WISCONSIN OVER THE LAST COUPLE HOURS. BASED OF
THE ORIENTATION OF THE MID LEVEL WINDS AND FORECASTED TRACK OF THE
FGEN...WOULD EXPECT THE PRECIPITATION TO SHIFT EAST-NORTHEAST
ACROSS THE WISCONSIN BORDER EARLY THIS EVENING AND THEN MOVE ACROSS
PORTIONS OF CENTRAL/EASTERN UPPER MICHIGAN. THE SNOW WILL BE
FIGHTING A DRY LAYER BETWEEN 900-800MB THIS EVENING...WHICH WILL
KEEP SNOW ACCUMULATIONS LIGHT AND GENERALLY JUST A DUSTING. BUT
DEPENDING ON WHERE THE HEAVIEST BAND TRACKS...THERE COULD BE A FEW
LOCATIONS THAT SEE AMOUNTS UP TO A HALF INCH.

THEN THE SECOND SHORTWAVE WILL LIFT NORTHEAST OVER THE SURFACE
TROUGH AND THROUGH WESTERN LAKE SUPERIOR AND WESTERN UPPER MICHIGAN
LATER TONIGHT AND FRIDAY. LIKE THE INITIAL WAVE OF
PRECIPITATION...MID LEVEL (800-600MB) FGEN WILL REDEVELOP OVER THE
WESTERN CWA AND SHIFT THE FOCUS OF THE SNOW TO THE NORTHWEST THROUGH
THE NIGHT...AS THE MID LEVEL WINDS BACK AND REMAIN OVER THE WESTERN
CWA DURING THE MORNING HOURS ON FRIDAY BEFORE DIMINISHING AS THE
SHORTWAVE (AND ASSOCIATED DEEPER MOISTURE) DEPARTS. HIGHER
RESOLUTION MODELS FAIRLY CONSISTENT IN A STRIPE OF 0.05-0.10IN OF
QPF OVER THE WESTERN THIRD OF UPPER MICHIGAN LATE TONIGHT THROUGH
FRIDAY MORNING. WITH MUCH OF THE FORCING WITHIN AND AROUND THE
DGZ...COULD SEE SNOW RATIOS A LITTLE HIGHER IN THE BETTER FGEN
AREAS (TOWARDS 13-15 TO 1). THIS LEADS TO SNOWFALL AMOUNTS FROM A
HALF INCH TO A LITTLE OVER AN INCH IN THOSE AREAS. THERE COULD BE A
LITTLE ADDED SNOWFALL FROM LAKE ENHANCEMENT BEHIND THE SURFACE
TROUGH. INITIALLY...THERE WILL BE A POCKET OF DRIER AIR AT AND ABOVE
850MB OVER WESTERN LAKE SUPERIOR...ALONG WITH GENERALLY LIGHT
WEST-NORTHWEST FLOW AT THAT LEVEL...WHICH WILL LIMIT THE POTENTIAL
FOR LAKE ENHANCEMENT TONIGHT. BUT AS THE DEEPER MOISTURE PIVOTS
NORTHWEST TOWARDS THAT AREA LATE TONIGHT AND CONTINUES INTO FRIDAY
MORNING...THERE COULD BE SOME LIGHT ENHANCEMENT FOR AREAS FAVORED BY
NORTHERLY WINDS (BOUNDARY LAYER WIND DIRECTION) AFTER THE SURFACE
TROUGH MOVES THROUGH. WITH THE INVERSION STAYING AROUND
3-4KFT...THERE SHOULDN/T BE MUCH ADDITIONAL HELP BUT IT MAY GIVE
ANOTHER COUPLE TENTHS OF AN INCH OF SNOW.

THE SHORTWAVE WILL LIFT OUT OF THE AREA DURING THE AFTERNOON AND
PULL MUCH OF THE DEEPER MOISTURE OUT OF THE AREA. THIS LEADS TO
SOME CONCERNS OF ICE CRYSTAL PRESENCE OVER THE CENTRAL/EASTERN CWA.
ALTHOUGH THE POTENTIAL FOR PRECIPITATION IS LOW...WILL ADD A
MENTION OF DRIZZLE WITH THE SLIGHT CHANCE POPS FOR THAT AREA.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 427 AM EST THU DEC 25 2014

LONGER RANGE MODELS INDICATE A SPLIT FLOW PATTERN WILL DOMINATE
NAMERICA INTO EARLY NEXT WEEK WITH AN UPR TROF IN BOTH BRANCHES
CENTERED OVER THE PLAINS. SINCE THE MODELS INDICATE THERE WL NO
PHASING BTWN THE SRN AND NRN BRANCH FLOWS...LOOKS LIKE THERE WL BE
NO MAJOR WINTER STORMS FOR UPR MI DURING THIS TIME. INITIAL FCST
CONCERN WL BE ON POTENTIAL FOR SOME WIDESPREAD LIGHT SN MAINLY LATE
ON FRI NGT INTO SAT IN ADVANCE OF A SRN BRANCH SHRTWV LIFTING NEWD
INTO THE GREAT LKS. FOCUS THEN SHIFTS ON INFLUX OF COLDER AIR AND
THE POTENTIAL FOR LES AS THE NRN BRANCH FLOW BECOMES THE DOMINANT
INFLUENCE OVER THE UPR LKS. ABOVE NORMAL TEMPS INTO SAT WL TREND BLO
NORMAL EARLY NEXT WEEK AS MANY OF THE LONGER RANGE MODELS SHOW H85
TEMPS FALLING AT LEAST NEAR -20C NEXT TUE.

FRI...A STATIONARY FNT UNDER THE SW FLOW ALOFT IN THE CONFLUENCE ZN
BTWN THE NRN AND SRN BRANCH FLOWS WL BE THE FOCUS FOR SOME LIGHT SN
OVER MAINLY THE NW HALF OF THE CWA INTO EARLY AFTN...WHERE AND WHEN
THE MODELS SHOW A PERIOD WHERE A POCKET OF SOME DEEP LYR QVECTOR
CNVGC WL BE IN PLACE OVER AXIS OF HIER MID LVL RH ASSOCIATED WITH
THE WAA PCPN CHCS ON THU NGT. A WEAK COLD FNT ASSOCIATED WITH A NRN
BRANCH SHRTWV MOVING ACROSS ONTARIO WL ALSO PUSH W TO E ACRS THE CWA
DURING THE DAY AND PUSH THE STNRY FNT TO THE E. DEEP LYR QVECTOR
DVGC ARRIVING IN THE WAKE OF THE ONTARIO DISTURBNANCE/SFC COLD FROPA
WL TEND TO DIMINISH PCPN CHCS LATER IN THE DAY. SINCE H85 TEMPS ARE
PROGGED TO FALL TO ONLY -9C TO -10C OVER THE FAR W TOWARD 00Z SAT
AND THE H925 NNW FLOW BEHIND THE FROPA IS FCST TO BE NEUTRAL TO
SLIGHTLY ACYC...EXPECT ONLY LO CHC POPS FOR LES EVEN IN THE FAVORED
SN BELTS.

FRI NGT/SAT...A STRONGER SHRTWV EMERGING OUT OF THE SRN BRANCH TROF
IN THE SCENTRAL PLAINS IS FCST TO MOVE NE TOWARD THE WESTERN GREAT
LKS ON FRI NGT...CAUSING THE DEPARTING SFC FNT TO STALL NOT TOO FAR
SE OF UPR MI. ALTHOUGH A WEAK LO PRES IS FCST TO ACCOMPANY THE
SHRTWV TO THE NE AND RIDE ALONG THE STNRY FNT...THE TRACK OF THE
SHRTWV THRU THE CONFLUENCE ZN BTWN THE SEPARATE BRANCHES SHOULD
CAUSE THIS DISTURBANCE TO SHEAR OUT/WEAKEN WITH TIME. THE 00Z CNDN
MODEL SHOWS THE MOST VIGOROUS SHRTWV/DYNAMIC SUPPORT...WITH SOME
MODERATE PCPN FALLING OVER MAINLY THE SCENTRAL ON SAT MRNG. BUT THIS
MODEL HAS SHOWN VERY POOR RUN-TO-RUN CONTINUITY. IN FACT...PAST RUNS
SHOWED THE MOST SHEARED OUT/WEAKER/DRIER SCENARIO. ALTHOUGH THE 00Z
ECMWF HAS TRENDED IN THIS DIRECTION AS WELL...OPTED TO FOLLOW THE
WEAKER 00Z NAM/12Z ECMWF SOLUTIONS. THE QPF FM THESE MODELS IS ABOUT
0.15 INCH OVER THE SCENTRAL CWA LATE FRI NGT INTO SAT AFTN...
CONSISTENT WITH H7 SPECIFIC HUMIDITY NEAR 2 G/KG. SINCE THE NAM FCST
SDNGS SHOW SOME SHARP UVV WITHIN AN EXPANDING DGZ...THERE COULD BE
2-3 INCHES OF SN IN SOME LOCATIONS IN THAT AREA. OPTED TO BUMP UP
POPS INTO THE LIKELY RANGE OVER ABOUT THE SE HALF OF THE CWA WHERE
THE MSTR IS DEEPEST AND AN AXIS OF H85-7 FGEN PASSES ON SAT MRNG.
THE ARRIVAL OF DEEP LYR QVECTOR DVGC IN THE WAKE OF THE DEPARTING
SHRTWV LATER IN THE DAY WL CAUSE THE SYNOPTIC SCALE SN TO DIMINISH
W-E. ARRIVAL OF H85 TEMPS AS LO AS -12 TO -13C TOWARD 00Z SUN IN THE
WNW FLOW LEFT IN THE WAKE OF THE DEPARTING SHRTWV WL BRING A RETURN
OF MORE LES.

SAT NGT/SUN...LARGER SCALE DNVA/DEEP LYR QVECTOR DVGC IN THE WAKE OF
THE DEPARTING SHRTWV WL DOMINATE MOST OF SAT NGT...BUT THE MEDIUM
RANGE MODELS SHOW A NRN BRANCH SHRTWV ARRIVING LATE SAT NGT AND SUN
WITH SOME DEEP LYR QVECTOR CNVGC/DEEPER MSTR. THIS SETUP COULD
SUPPORT SOME LK ENHANCED SN OVER THE NRN TIER COUNTIES...ESPECIALLY
ALONG LK INDUCED TROF AND WHERE THE LLVL NW FLOW IS MOST FAVORABLE.
GFS FCST SDNGS INDICATE FAVORABLE UVV PROFILE WITHIN A FAIRLY DEEP
DGZ AS WELL.

SUN NGT THRU WED...LONGER RANGE 00Z MODELS SHOW COLDER CANADIAN AIR
STEADILY SURGING INTO THE AREA IN THE NNW FLOW E OF ARCTIC HI PRES
BLDG FM WRN CANADA INTO THE NRN PLAINS. MOST OF THE GUIDANCE SHOWS
THE H85 TEMP FALLING TO AROUND -20C BY 00Z TUE...SO TEMPS WL FALL
BLO NORMAL. THIS SETUP IS A FVRBL ONE FOR LES. ALTHOUGH THE GFS FCST
SNDGS SHOW THE INVRN SINKING AS LO AS 4K FT AGL DURING THIS TIME
FOLLOWING THE DEPARTURE OF THE SHRTWV SUN NGT...OPTED TO BUMP POPS
ABOVE THE CONENSUS FCST INTO THE LIKELY RANGE IN AREAS FAVORED BY
THE EXPECTED LLVL WINDS. AS ANOTHER SHRTWV APRCHS TOWARD NEXT WED...
THE LLVL FLOW MAY BACK SUFFICIENTLY TO SHIFT THE LES OVER MAINLY THE
KEWEENAW AND THE OPEN WATERS OF LK SUP AT THAT TIME.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1242 PM EST THU DEC 25 2014

MOIST SOUTHWESTERLY FLOW BETWEEN A DEPARTING RIDGE AND A TROUGH
LOCATED IN MINNESOTA CONTINUES TO LEAD TO MVFR CEILINGS AT THE TAF
SITES. THERE HAVE BEEN TIMES WHERE THE SOUTHWESTERLY DOWNSLOPE FLOW
AT KIWD/KSAW LED TO THE LOW CLOUDS SCATTERING OUT. BELIEVE THAT
BETTER MOISTURE ARRIVING AT KIWD WILL KEEP THEM IN MVFR CONDITIONS
FOR THE REST OF THE AFTERNOON. CONFIDENCE IS LOWER AT KSAW BASED
OFF THE EDGE OF THE CLOUDS BEING LOCATED JUST TO THE NORTHEAST OF
THE SITE. IN ADDITION...KIMT UPSTREAM DID HAVE CEILINGS RISE TO
VFR OVER THE LAST COUPLE HOURS AND COULD BE AN INDICATION OF A
BRIEF PERIOD OF VFR. OPTED TO GO WITH LOW END MVFR FOR NOW AND
TREND TOWARDS HIGHER MVFR LATER THIS AFTERNOON...BUT WOULD NOT BE
SURPRISED IF THERE ARE A FEW PERIODS OF VFR.

FOR TONIGHT...A COUPLE WEAK DISTURBANCES WILL SHIFT NORTHEAST
THROUGH UPPER MICHIGAN. THE FIRST WAVE WILL LARGELY AFFECT CENTRAL
UPPER MICHIGAN AND HAVE SHOWN A PERIOD OF MVFR VISIBILITIES AS THE
SNOW MOVES THROUGH KSAW. AS THE SECOND WAVE ARRIVES OVERNIGHT...THE
BETTER SNOWFALL WILL SHIFT TO THE NORTHWEST AND AFFECT KCMX/KIWD.
EXPECT VISIBILITIES TO LARGELY STAY MVFR...BUT DID BRING KIWD DOWN
TO IFR FOR A PERIOD LATE TONIGHT INTO FRIDAY MORNING AS WINDS SHIFT
TO THE NORTH AND LAKE ENHANCEMENT INCREASES THE SNOWFALL INTENSITY.
THIS SNOW WILL SHIFT OUT OF THE WESTERN U.P. DURING THE AFTERNOON
ON FRIDAY.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 248 PM EST THU DEC 25 2014

SOUTHWESTERLY WINDS HAVE INCREASED OVER LAKE SUPERIOR (UP TO 25KTS)
BETWEEN A DEPARTING HIGH PRESSURE RIDGE AND A TROUGH IN MINNESOTA.
THIS TROUGH WILL WEAKEN AS IT MOVES OVER LAKE SUPERIOR TONIGHT AND
THEN STALLS OVER FAR EASTERN LAKE SUPERIOR FRIDAY INTO FRIDAY
NIGHT. THIS WEAK PRESSURE GRADIENT WILL ALLOW WINDS TO SHIFT TO THE
NORTH AND FALL BELOW 15KTS TONIGHT AND REMAIN INTO FRIDAY NIGHT. A
LOW MOVING NORTHEAST ALONG THE TROUGH ON SATURDAY WILL INCREASE
THE NORTH AND EVENTUALLY NORTHWEST WINDS ON SATURDAY AFTERNOON AND
SATURDAY NIGHT...WITH GUSTS UP TO 30KTS OVER THE EASTERN LAKE. THE
REST OF THE PERIOD WILL EXPERIENCE NORTHWEST TO NORTHERLY WINDS
UNDER 25KTS AS A STRONG HIGH BUILDS INTO THE NORTHERN/CENTRAL
PLAINS.
&&

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

$$

SHORT TERM...SRF
LONG TERM...KC
AVIATION...SRF
MARINE...SRF





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