Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 132315
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
715 PM EDT SAT SEP 13 2014

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 409 PM EDT SAT SEP 13 2014

WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW THE VIGOROUS SHORTWAVE
THAT PRODUCED PCPN OVER MUCH OF UPPER MI LAST NIGHT NOW MOVING THRU
SRN ONTARIO INTO QUEBEC. UPSTREAM...A PAIR OF SHORTWAVES ARE
NOTED...ONE OVER ND/SRN MANITOBA AND THE OTHER OVER SRN
SASKATCHEWAN. THESE WAVES WILL BRING THE NEXT PCPN CHC TO UPPER MI
ON SUNDAY. IN THE WAKE OF LAST NIGHTS SYSTEM...850MB TEMPS ARE
CURRENTLY -1 TO -2C OVER LAKE SUPERIOR. TYPICALLY AT THIS TIME OF
YEAR...THIS WOULD BE MORE THAN SUFFICIENT FOR LAKE EFFECT CLOUDS AND
PCPN. HOWEVER...WITH A LARGE PORTION OF LAKE SUPERIOR HAVING SFC
WATER TEMPS PROBABLY ONLY AROUND 7-9C...THERE WAS NOT MUCH IN THE
WAY OF LAKE EFFECT CLOUDS EARLIER TODAY. IN FACT...THE LAKE HAS
BEHAVED MOSTLY AS STABILIZING INFLUENCE. ONE BAND WITH A FEW
SPRINKLES DID STREAM INTO ERN MARQUETTE COUNTY BRIEFLY THIS MORNING
DUE TO LAND BREEZE CONVERGENCE AND WARMER WATER TO THE S AND E OF
THE KEWEENAW. THIS AFTN...DAYTIME HEATING/LOW-LEVEL CONVERGENCE AND
MOISTURE FROM THE LAKE RESULTED IN ADDITIONAL SPRINKLES DEVELOPING
IN ERN MARQUETTE COUNTY. THESE SPRINKLES ARE DRIFTING SE THRU DELTA
AND WRN ALGER COUNTIES. WHILE LAKE EFFECT CLOUDS WERE AT A MINIMUM
EARLIER TODAY...850MB THERMAL TROF COMBINED WITH ADDED MOISTURE FROM
THE LAKE RESULTED IN WIDESPREAD CU/STRATOCU DEVELOPING OVER THE LAND
ONCE DAYTIME HEATING BEGAN.

TONIGHT...MAIN FCST CONCERN IS FROST POTENTIAL. WHILE CU/STRATOCU IS
STILL QUITE EXTENSIVE...THE DIURNAL NATURE OF THE CLOUD DEVELOPMENT
SUGGESTS THE CLOUDS WILL DISSIPATE THIS EVENING WITH THE LOSS OF
DAYTIME HEATING. MEANWHILE...LEAD SHORTWAVE TO THE W IS GENERATING A
FAIR AMOUNT OF HIGH CLOUDINESS WHICH WILL STREAM OVER THE FCST AREA
AS THE WAVE MOVES OVER THE UPPER LAKES. DISSIPATING STRATOCU THIS
EVENING BEING REPLACED BY HIGH CLOUDS WILL BE ONE FACTOR HELPING TO
KEEP TEMPS FROM CRASHING. OTHER FACTOR WILL BE DEPARTURE OF HIGH
PRES RIDGE CURRENTLY OVER THE AREA. AS PRES GRADIENT TIGHTENS BTWN
THE EXITING HIGH AND APPROACHING SFC TROF... THERE WILL BE SOME
INCREASE IN MIXING. THAT SAID...THE INITIAL DRY AIR MASS
(PRECIPITABLE WATER 45-55PCT OF NORMAL) AND LIGHT WINDS OVER THE
AREA WILL STILL ALLOW TEMPS TO FALL INTO THE MID 30S AND TO EVEN THE
LOWER 30S IN TRADITIONAL COLD SPOTS. SO...FCST WILL SHOW PATCHY
FROST OVER MUCH OF THE INTERIOR. AT THIS POINT...NOT EXPECTING
COVERAGE TO BE LARGE ENOUGH TO WARRANT A FROST ADVY. EVENING SHIFT
WILL NEED TO MONITOR CLOUD TRENDS AND TEMPS TO RE-EXAMINE THE NEED
FOR HEADLINE ISSUANCE BY LATE EVENING.

ON SUN...SECOND SHORTWAVE WILL SWING ACROSS THE UPPER GREAT LAKES.
AS IN PREVIOUS DAYS...MODELS CONTINUE TO INDICATE BEST
MOISTURE/FORCING PASSING JUST N OF THE AREA...ALONG AND N OF
PROJECTED VORT TRACK. SEE NO REASON TO DEVIATE MUCH FROM PREVIOUS
FCST WITH MAINLY CHC POPS SPREADING INTO WRN UPPER MI IN THE MID TO
LATE MORNING AND THEN REACHING THE E MID TO LATE AFTN. EXPECT HIGH
TEMPS GENERALLY IN THE UPPER 50S TO LWR 60S.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 350 PM EDT SAT SEP 13 2014

SPLIT FLOW PATTERN ALOFT TO START THE LONG TERM PERIOD BUT NORTHERN
BRANCH IS BY FAR STRONGER AND MORE INFLUENTIAL ON THE WEATHER OVER
MUCH OF NORTH AMERICA. TROUGHING CENTERED OVER NUNAVUT CANADA TO THE
NORTH OF HUDSON BAY WILL KEEP A TROUGH/BELOW NORMAL TEMPS OVER MOST
OF CANADA AND INTO THE GREAT LAKES AND REST OF THE EASTERN CONUS
THIS WEEK. RIDGING OVER THE WESTERN CONUS AND WESTERN CANADA SHOULD
SLOWLY SLIDE EAST BY THE END OF THE WEEK AS DEEP TROUGH CURRENTLY
OVER ALASKA RE-ORIENTS OVER THE GULF OF ALASKA WHILE SLIGHTLY
OPENING UP. MAY SEE A WARM UP LATE THIS WEEK AND BEYOND AS
RIDGING...OR AT LEAST LESS TROUGHING...AFFECTS THE PLAINS AND GREAT
LAKES. PATTERN DOES NOT LOOK TO PROVIDE MUCH IN WAY OF RAIN THE NEXT
WEEK. PRIMARY CHANCES WOULD BE WITH COLD FRONT MOVING THROUGH ON
TUESDAY NIGHT AND AGAIN BY NEXT WEEKEND AS WARM AIR ADVECTION STARTS
TO SPREAD IN FROM THE WEST.

SUNDAY NIGHT INTO MONDAY...SHORTWAVE AND ASSOCIATED COLD FRONT MOVES
OUT OF EASTERN CWA AFTER MIDNIGHT ON SUNDAY NIGHT. WILL LINGER SLIGHT
CHANCE POPS OVER THE EAST AFTER MIDNIGHT. THERMAL TROUGH WITH LOWER
H7 TEMPS AND A POCKET OF H85-H7 RH ALONG WITH DAYTIME HEATING MAY
RESULT IN ISOLD SHRA VCNTY OF LAKE BREEZES OVER EASTERN CWA ON
MONDAY AFTN. DRYING AND SUBSIDENCE IN WAKE OF THE SUNDAY NIGHT
SHORTWAVE SHOULD LIMIT COVERAGE AND WILL ONLY KEEP SLIGHT CHANCES.
LI/S ARE A BIT BLO 0C BUT THINK THAT WITH FROPA WITHIN PREVIOUS 12
HR...THERE WILL ONLY BE ENOUGH INSTABILITY FOR SHRA SO DID NOT
MENTION ANY THUNDER.

SFC RIDGE SETTLES FROM THE NORTHERN PLAINS TO THE OHIO VALLEY BY
TUESDAY MORNING. COULD BE HIGH CLOUDS ON MONDAY NIGHT...BUT PWATS
ARE BLO 50 PCT OF NORMAL SO IT COULD BE CHILLY NIGHT WITH SOME FROST
POSSIBLE. WINDS LIGHT NEAR THE RIDGE AND THERE IS LIMITED ONSHORE
COMPONENT ANYWHERE IN CWA...SEEMS THAT ALL INTERIOR WOULD BE AT RISK
FOR THE COLD TEMPS/FROST. TUESDAY SHOULD BE DRY AS UPPER LAKES IS
BTWN THE RIDGE AND AN APPROACHING COLD FRONT. WSW WINDS AHEAD OF
FRONT AND H85 TEMPS UP TO 4-6C SHOULD RESULT IN TEMPS INTO THE 60S
WHICH IS AT LEAST CLOSER TO NORMAL. FRONT DROPS NORTH TO SOUTH OVER
THE AREA ON TUESDAY NIGHT OR WEDNESDAY MORNING. A BRIEF INTERLUDE OF
INCREASING H8-H6 MOISTURE AND WEAK LIFT JUST IN WAKE OF THE FRONT
MAY BE ENOUGH TO KICK OFF SOME SHOWERS TUESDAY NIGHT. COVERAGE OF
ANY SHOWERS WILL BE HELD BACK AS STRONGER FORCING FOR LIFT REMAINS
OVER NORTHERN ONTARIO CLOSER TO TRACK OF UPPER LEVEL JET DIGGING
INTO THE PERSISTENT TROUGH. INTO WEDNESDAY...COULD BE A LOT OF LOW
CLOUDS LINGERING BENEATH SUBSIDENCE ALOFT AS SUB H85 IT REMAINS COOL
AND MOIST WITH EASTERLY FLOW. ADDITIONAL MID CLOUDS MAY STREAM ACROSS
IN THE AFTN AS WELL. TEMPS WILL BE MUCH COOLER THAN THE DAY BEFORE
AND IT WILL ESPECIALLY FEEL THAT WAY WITH THE CLOUDS AND EAST WIND.
TEMPS IN THE LOW 50S NEAR LK SUPERIOR AND NEAR 60 OVER THE SCNTRL.

AS TROUGH ALOFT OVER EASTERN CANADA AND THE NORTHEAST CONUS SLOWLY
MOVES EAST AND RIDGE OVER WESTERN CONUS ALSO MOVES EAST...CONFLUENT
FLOW RESULTS IN SFC RIDGE MOVING FROM CNTRL CANADA ACROSS THE GREAT
LAKES AND EVENTUALLY TO THE EASTERN SEABOARD BY SATURDAY. DRY WEATHER
SHOULD HOLD OVER UPPER LAKES THROUGH THU NIGHT...WITH CHANCES
FOR RAIN INCREASING BY NEXT WEEKEND AS SHORTWAVE TROUGH MOVES TO THE
CNTRL PLAINS AND SFC FRONT SLIDES EASTWARD. LATEST GFS WHICH HAD
BEEN VERY AGRESSIVE IN PREVIOUS MODEL RUNS BRINGING QPF TO THE
UPPER GREAT LAKES BY FRIDAY NOW LOOKS SIMILAR TO THE SLOWER 00Z
ECMWF. ON THE FLIP SIDE...THE LATEST ECMWF IS MUCH MORE BULLISH
BRINGING QPF ACROSS ALL OF UPR MICHIGAN BY FRIDAY AFTN AS WHERE IT
HAD BEEN INSISTENT ON A RIDGE...IT HAS A STRONGER SHORTWAVE TROUGH.
MODEL CONSISTENCY IS LACKING AND WILL GO WITH A CONSENSUS OF ALL THE
MODELS WITH LOW CHANCES FOR SHRA/TSRA BEGINNING ON FRIDAY AND
LASTING INTO NEXT WEEKEND. GENERALLY...TEMPS WILL RUN BELOW NORMAL
THE UPCOMING WEEK...THOUGH IT DOES APPEAR THAT IN ADDITION TO THE
WARMER TEMPS ON TUESDAY AHEAD OF A COLD FRONT...READINGS ON FRIDAY
AND SATURDAY MAY TRY TO PUSH TO AROUND NORMAL. WILL ALL DEPEND ON
EXTENT OF CLOUDS AND SHRA/TSRA. COUPLE OF CHILLY NIGHTS POSSIBLE
WEDNESDAY NIGHT AND THURSDAY NIGHT AS THE HIGH IS IN THE VCNTY AND
PWATS ARE WELL BLO 50 PCT OF NORMAL. IF SKIES ARE MAINLY CLEAR
EITHER NIGHT...TEMPS COULD BE AROUND FREEZING AND THERE WOULD BE
FROST. ATTM...BEST CHANCE FOR IDEAL RADIATIONAL COOLING CONDITIONS
WOULD BE ON WEDNESDAY NIGHT.
&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 715 PM EDT SAT SEP 13 2014

UNDER RELATIVELY DRY LOW LEVELS...VFR CONDITIONS WILL PREVAIL THRU
THE FCST PERIOD AT KIWD/KCMX/KSAW. ON SUN...AN APPROACHING LOW PRES
TROF SHOULD BRING SCT -SHRA INTO NW UPPER MI BY AFTN. HAVE INCLUDED
A VCSH MENTION AT KCMX.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 409 PM EDT SAT SEP 13 2014

APPROACHING LOW PRES TROF WILL RESULT IN INCREASING S TO SW WINDS
TONIGHT INTO SUN. WHILE LOWER OBS PLATFORMS SHOULDN`T SEE WINDS
GREATER THAN THE 10-20KT RANGE...HIGH OBS PLATFORMS WILL PROBABLY
SEE GUSTS TO AROUND 25KT. WINDS SHOULD FALL BACK TO MOSTLY 10-20KT
SUN NIGHT THRU MON. THERE MAY BE SOMEWHAT HIGHER WINDS AGAIN LATE
MON NIGHT THRU EARLY WED AHEAD OF AND BEHIND A COLD FRONT THAT WILL
DROP S ACROSS LAKE SUPERIOR TUE. LIGHTER WINDS WILL THEN BE THE RULE
LATER WED THRU THU HAS HIGH PRES MOVE SE ACROSS NRN ONTARIO TOWARD
THE LOWER LAKES.
&&

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

$$

SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...07
MARINE...ROLFSON






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