Area Forecast Discussion
Issued by NWS Marquette, MI

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636
FXUS63 KMQT 042101
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
401 PM EST THU FEB 4 2016

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 400 PM EST THU FEB 4 2016

...LIGHT LAKE EFFECT SNOW TONIGHT INTO FRI MORNING...

DEEP TROUGH IS OVER THE CENTRAL CONUS TODAY WITH A RIDGE UPSTREAM
OVER WESTERN CONUS AND A SHARP RIDGE DOWNSTREAM OVER WESTERN
ATLANTIC OCEAN. ONE SHORTWAVE IS WORKING THROUGH IN THE NW FLOW
ALOFT WITH WEAK SFC TROUGH MOVING OVER WESTERN LK SUPERIOR INTO FAR
WESTERN UPR MICHIGAN. 12Z KINL RAOB SHOWED INCREASING H9-H8 MOISTURE
WITH SHARP LOW-LEVEL INVERISON BLO H85. THOUGH DEPTH OF MOISTURE IS
LIMITED...SCATTERED LGT SNOW/FLURRIES ARE MOVING OVER WESTERN UPR
MICHIGAN. AS THIS INITIAL SHORTWAVE MOVES ACROSS THIS EVENING YET
ANOTHER WAVE CURRENTLY MOVING OVER NW ONTARIO DIPS DOWN OVER LK
SUPERIOR/UPR MICHIGAN THIS EVENING...EXPECT THE SFC TROUGH TO SLIDE
ACROSS. WITH WEAK Q-VECTOR CONVERGENCE AND BRIEF MOISTURE AND LIFT
UP TO H7 MAY SEE LGT SNOW AND FLURRIES OVER WESTERN CWA SPREAD OVER
CENTRAL AND EAST CWA THIS EVENING...BEFORE EXITING BY MIDNIGHT.
SKIES MAY TRY TO CLEAR AWAY FM LK SUPERIOR SCNTRL...SO COULD SEE
LOWS DIP INTO THE SINGLE DIGITS. LOW TO MID TEENS EXPECTED ELSEWHERE.

MAIN IMPACT OF THE TROUGH WILL BE TO SWING WINDS MORE NW BY LATER
THIS EVENING ALLOWING FOR AN INCREASE TO LAKE EFFECT SNOW FOR NW
WIND SNOWBELTS AS H85 TEMPS FALL TO -14C TO -16C. STRONGEST
CONVERGENCE FOR MOST OF NIGHT IS PEGGED FOR WESTERN CWA OVER COPPER
COUNTRY...ROUGHLY BTWN ONTONAGON AND CALUMET...BUT LK EFFECT WILL
ALSO INCREASE LATE TONIGHT INTO FRI OVER NORTH AND EAST UPR
MICHIGAN...MOSTLY TO EAST OF MUNISING. FORECAST SOUNDINGS FOR LAKE
EFFECT AREAS SHOW MID-LEVEL MOISTURE EXITING LATER THIS EVENING BUT
MOIST LAYER LEFT OVER TO H8/5KFT IS SQUARELY IN THE DGZ AND WINDS IN
THAT LAYER ARE NOT STRONG. SO...EXPECT THE SNOW TO BE FLUFFY WITH
ISOLD AMOUNTS OVER 4 INCHES IN FAVORED SNOW BELTS. WILL NOT DO ANY
LAKE EFFECT HEADLINES AS MOST AREAS WILL JUST SEE A FEW INCHES OF
FLUFF SNOW AND SINCE BLSN WILL BE MINIMAL ISSUE. LATER ON FRI WINDS
BACK MORE WSW-SW AHEAD OF ANOTHER SHORTWAVE TROUGH/SFC TROUGH MOVING
TOWARD UPPER GREAT LAKES LATE IN THE DAY. KEPT SMALL POPS FOR LAKE
EFFECT UNTIL WINDS SHIFT OFFSHORE...WHICH COULD BE MID-LATE AFTN
OVER FAR EAST CWA. AWAY FM THE LAKE EFFECT AREAS...MAY SEE SOME
PARTIAL SUNSHINE TO START THE DAY WITH MID-HIGH CLOUDS MOVING IN
LATE. HIGHS ALL AREAS SHOULD REACH INTO THE 20S.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 535 AM EST THU FEB 4 2016

A MEAN TROF IS CURRENTLY IN THE PROCESS OF BECOMING ESTABLISHED OVER
THE E HALF OF N AMERICA DONWSTREAM OF A MEAN RIDGE POSITION
BASICALLY ALONG THE W COAST OF N AMERICA. ONE SHORTWAVE TROF WILL
SHIFT ACROSS THE MISSISSIPPI VALLEY/GREAT LAKES EARLY IN THE
WEEKEND. RAPID BUILDING OF POSITIVE HEIGHT ANOMALIES IN THE WRN
RIDGE LATE IN THE WEEKEND WILL THEN LEAD TO SHARP AMPLIFICATION OF
THE TROF OVER THE ERN CONUS EARLY NEXT WEEK. THIS WILL SPELL THE
ONSET OF A COLD/BLO NORMAL TEMP REGIME FOR THE UPPER GREAT LAKES.
THERE ARE STILL SOME INDICATIONS OF A BITTERLY COLD AIR MASS DIVING
INTO THE UPPER LAKES IN THE FEB 11 TO FEB 13 TIME FRAME. HOWEVER...
HOW FAR S THE BUILDING BITTER COLD AIR MASS SPREADS WILL DEPEND ON
THE AMPLITUDE OF THE WRN RIDGE. INCLUDING RECENT OPERATIONAL GFS
RUNS...THERE ARE STILL SOME CANADIAN ENSEMBLES MAINTAINING A STRONG
WRN RIDGE WHICH WOULD FORCE THE BITTER COLD AIR INTO THE UPPER GREAT
LAKES. ON THE OTHER HAND...THERE APPEARS TO SOME OVERALL TRENDING
TOWARD A LESS AMPLIFIED WRN RIDGE WHICH DIMINISHES THE POTENTIAL FOR
AN UNUSUALLY COLD AIR MASS TO DESCEND INTO THE UPPER GREAT LAKES.
WILL BE SOMETHING TO MONITOR OVER THE COMING WEEK. WHATEVER
HAPPENS...THE UPCOMING COLD PATTERN SHOULD BE FAIRLY SHORT LIVED
WITH INDICATIONS OF A RETURN TO ABOVE NORMAL TEMPS DURING THE LAST
HALF OF FEB. AS FOR PCPN...THE DEVELOPING COLD PATTERN WILL
OBVIOUSLY MEAN NEXT WEEK WILL BE AN ACTIVE PERIOD FOR LAKE EFFECT
SNOW OFF LAKE SUPERIOR. PRIOR TO THAT...THERE WILL BE SOME LIGHTER
LES INTO THE EARLY PART OF THE WEEKEND THAT WILL BRIEFLY BE ENHANCED
BY PASSING SHORTWAVE TROF FRI NIGHT/SAT MORNING. SHARP TROF
AMPLIFICATION EARLY NEXT WEEK SHOULD YIELD AT LEAST A WIDESPREAD -SN
ACROSS UPPER MI AS WELL AS LAKE ENHANCEMENT. THERE HAS BEEN A FAIRLY
STRONG SIGNAL FOR MDT TO PERHAPS HVY LES OFF LAKE SUPERIOR TO FOLLOW
THIS SYSTEM INTO TUE AND PERHAPS WED.

BEGINNING FRI...IN THE WAKE OF THE SHORTWAVE THAT PASSES TONIGHT...
LINGERING LES IN THE NW WIND FAVORED SNOW BELTS E OF MARQUETTE FRI
MORNING WILL DIMINISH AS INVERSION FALLS FROM 7-8KFT EARLY TO 4KFT
IN THE AFTN. INITIAL HIGH INVERSION MAY SUPPORT A COUPLE OF INCHES
OF SNOW LOCALLY. WITH INVERSION ALREADY FALLING OUT W BY 12Z...LES
WILL BE LIGHTER. SFC HIGH PRES RIDGE WILL DRIFT ACROSS THE AREA
DURING THE DAY...RESULTING IN THE LINGERING/DIMINISHING LES SHIFTING
OFFSHORE FROM W TO E. WILL BE CLOSE TO 00Z SAT BEFORE ENDING E OF
GRAND MARAIS. WITH THE BACKING WINDS...SHOULD SEE SOME SUNSHINE
WHERE LAKE CLOUDS DEPART...THOUGH INCREASING HIGH CLOUDS AHEAD OF
NEXT SHORTWAVE TROF WILL PREVENT THE DAY FROM BECOMING SUNNY.

AFOREMENTIONED SHORTWAVE TROF AND ASSOCIATED COLD FRONT WILL CROSS
THE UPPER GREAT LAKES LATE FRI NIGHT/SAT MORNING. WHILE MOISTURE
INFLOW WILL BE LACKING...MODELS INDICATE DEEP MOISTENING OF THE
COLUMN/MODEST DEEP LAYER FORCING PER QVECTORS AND WEAK ISENTROPIC
ASCENT THAT SHOULD LEAD TO RELATIVELY HIGH POPS...BUT LOW QPF FRI
NIGHT. WITH 850MB TEMPS AROUND -12C ALONG COLD FRONT WHEN IT PASSES
ACROSS LAKE SUPERIOR...EXPECT A BRIEF BURST OF LAKE ENHANCED SNOW TO
ACCOMPANY ITS ARRIVAL IN UPPER MI LATE FRI NIGHT/SAT MORNING...
ESPECIALLY ACROSS THE NW FCST AREA AND ALSO MOSTLY E OF KMQT AS
WINDS SHIFT NNW. MIGHT SEE 2-3 INCHES OF SNOW WITH THE LAKE
ENHANCEMENT. LES WILL THEN DIMINISH DURING THE DAY SAT UNDER FALLING
INVERSION AND ARRIVAL OF SOME LOW-LEVEL DRYING.

SUN/MON...DOWNSTREAM OF THE AMPLIFYING WRN RIDGE...NEXT SHORTWAVE
WILL DROP MORE SHARPLY INTO THE CNTRL CONUS. RECENT ENSEMBLE AND
OPERATIONAL MEDIUM RANGE MODEL TRENDS ARE FOR THE LOW PRES RESPONSE
AT THE SFC TO BE FARTHER N WHICH WOULD PUSH THE MORE PERSISTENT
SYNOPTIC SNOW SHIELD MOSTLY N OF THE AREA...BUT THAT REMAINS TO BE
SEEN WITH SYSTEM STILL SEVERAL DAYS OUT IN THE MODEL RUNS. IN ANY
EVENT...STILL EXPECT ALL AREAS TO SEE SOME -SN AT TIMES SUN/MON.
LAKE ENHANCEMENT WILL ALSO OCCUR NEAR LAKE SUPERIOR...BUT
TIMING/LOCATION WILL REMAIN UNCERTAIN UNTIL MODELS NARROW IN ON THE
SFC LOW PRES/WIND FIELDS. RIGHT NOW...IT APPEARS SNOW WILL REALLY
BEGIN TO PICK UP NEAR LAKE SUPERIOR OVER THE W ON MON AS WINDS BACK
NORTHERLY AND CAA BEGINS. SNOW WILL THEN INCREASE EASTWARD ACROSS
NCNTRL UPPER MI MON NIGHT/TUE. GFS CONTINUES BE MOST PERSISTENT
HANGING ON TO DEEP MOISTURE ACROSS THE AREA THRU TUE AND THUS IS
MUCH MORE SUPPORTIVE OF A MDT/HVY LES REGIME ACROSS THE N WIND
FAVORED SNOW BELTS THRU TUE. EVEN IF THE DEEP MOISTURE THINS
OUT...850MB TEMPS FALLING INTO THE -15 TO -20C RANGE SUPPORTS GOING
WELL ABOVE CONSENSUS POPS NEAR LAKE SUPERIOR. POPS WERE BUMPED UP
INTO THE CATEGORICAL RANGE W ON MON...THEN ACROSS MOST AREAS NEAR
LAKE SUPERIOR MON NIGHT/TUE. CONTINUED HIGHER THAN CONSENSUS POPS
INTO WED AS WELL.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1239 PM EST THU FEB 4 2016

A WEAK UPPER DISURBANCE AND SURFACE LOW WILL MOVE THROUGH THE AREA
THIS EVENING. SOME LIGHT SNOW IS POSSIBLE WITH MVFR CIGS/VSBYS AT
ALL SITES THIS AFTN INTO THIS EVENING. BEHIND THE LOW...THE WINDS
WILL TURN W-NW WITH SOME LIGHT LAKE EFFECT SNOW POSSIBLE MAINLY AT
CMX/IWD. VSBYS COULD TURN IFR AT CMX FOR A PERIOD OVERNIGHT...BUT AM
NOT EXPECTING ANY LIFR CONDITIONS AT THIS TIME. IMPROVING CONDITIONS
ON FRIDAY WITH HIGH PRES BUILDING INTO THE AREA.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 400 PM EST THU FEB 4 2016

A LOW PRESSURE TROUGH MOVING ACROSS LK SUPERIOR THIS EVENING COULD
RESULT IN NW WINDS TO 30 KTS LATER THIS EVENING AND OVERNIGHT ON
EASTERN LK SUPERIOR. WINDS DIMINISH TO 25 KTS OR LESS ON FRI THEN
INCREASE TO W-SW TO 30 KTS FRI NIGHT AHEAD OF ANOTHER LOW PRESSURE
TROUGH. NW WINDS 20-30 KTS EXPECTED ON SAT BEHIND THE TROUGH. WINDS
BECOME SE TO 30 KTS ON SUN AHEAD OF A STRONGER CLIPPER LOW PRESSURE
SYSTEM MOVING TOWARD THE UPPER GREAT LAKES FM SCNTRL CANADA. GALES
MAY OCCUR OVER THE EAST HALF SUN AND SUN NIGHT. STRONGER N WINDS
COULD THEN REACH GALE FORCE ONCE THIS LOW MOVES BY NEXT MON INTO
TUE.
&&

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

$$

SHORT TERM...JLA
LONG TERM...ROLFSON
AVIATION...MRD
MARINE...JLA



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