Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 261732
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
132 PM EDT SUN APR 26 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 507 AM EDT SUN APR 26 2015

WATER VAPOR IMAGERY AND RAP ANALYSIS SHOW MID LEVEL RIDGE EXTENDING
FROM THE NRN PLAINS TO SRN HUDSON BAY. TO THE SE...A MID LEVEL LOW
IS CENTERED OFF THE CANADIAN MARITIMES WITH ITS BROAD CIRCULATION
EXTENDING BACK TO THE UPPER LAKES. TWO SHORTWAVES OF NOTE ARE
SWINGING W IN THE MID LEVEL LOW CIRCULATION ACROSS SE CANADA. THE
FIRST IS S OF JAMES BAY AND THE SECOND IS N OF MAINE. AT THE SFC...
THE MID LEVEL RIDGE IS SUPPORTING HIGH PRES RIDGING S FROM HUDSON
BAY INTO THE UPPER MISSISSIPPI VALLEY. UNDER DRY AIR MASS PER 00Z
REGIONAL SOUNDINGS...CLEAR SKIES CONTINUE TO PREVAIL ACROSS THE FCST
AREA EARLY THIS MORNING. TO THE NE...FIRST SHORTWAVE S OF JAMES IS
HELPING TO SPREAD SCT-BKN CLOUDS TOWARD LAKE SUPERIOR.

THE FIRST SHORTWAVE S OF JAMES BAY WILL ROTATE INTO NRN LWR MI THIS
AFTN/EVENING...SPREADING SOME CLOUDINESS INTO THE ERN FCST AREA
TODAY. TRENDS IN THE MODELS SHOW A BACKING OFF ON THE POTENTIAL
CLOUD COVER WHICH SEEMS REASONABLE BASED ON OVERNIGHT SATELLITE
IMAGERY. FCST THUS REFLECTS A MORE OPTIMISTIC SKY CONDITION FOR
CNTRL UPPER MI TODAY. MAY STILL SEE SOME PERIODS OF MOSTLY CLOUDY
CONDITIONS OVER THE ERN FCST AREA THIS AFTN...ESPECIALLY LATE. AS
FOR TEMPS...RATHER BRISK GRADIENT FLOW OFF LAKE SUPERIOR WILL HOLD
TEMPS TO THE LOWER 40S NEAR LAKE SUPERIOR TODAY. MOST LAKESIDE
LOCATIONS FROM THE KEWEENAW EASTWARD WILL NOT GET OUT OF THE 30S.
WELL INLAND...NAM/GFS FCST SOUNDINGS AND PROJECTED MIXING HEIGHTS
SUGGEST HIGH TEMPS MAY STRUGGLE TO REACH 50F. THERE MAY BE SOME LWR
50S TOWARD THE MI/WI BORDER FROM MENOMINEE COUNTY TO IRON COUNTY.

TONIGHT...SECOND SHORTWAVE NOW N OF MAINE WILL FOLLOW THE SAME TRACK
AS THE FIRST AND SHOULD REACH NRN LWR MI LATE TONIGHT. MODELS ARE
AGGRESSIVE IN SWINGING MOISTURE BACK INTO UPPER MI TONIGHT WITH THIS
FEATURE. OF PARTICULAR NOTE IS THE LOW-LEVEL MOISTURE THE NAM/GFS
SHOW. LOOKING TO THE NE...LOW CIGS ARE NOTED IN AND AROUND JAMES BAY
AND EASTWARD EARLY THIS MORNING. WITH THIS MOISTURE PUSHING SW INTO
THE AREA DURING THE NIGHT WHEN DAYTIME HEATING IS ABSENT TO HELP
LIFT OR MIX MOISTURE OUT...IT LOOKS FAIRLY LIKELY THAT LOW CLOUDS
WILL DEVELOP/EXPAND TONIGHT...ESPECIALLY LATE...OVER AT LEAST THE
NCNTRL AND E...AIDED BY UPSLOPE FLOW. NAM FCST SOUNDINGS EVEN
SUGGEST THE POTENTIAL FOR SOME -DZ/-FZDZ WHERE STRONGEST UPSLOPE
OCCURS. WILL BE SOMETHING TO TAKE A LOOK AT AGAIN IN LATER MODEL
RUNS.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 400 AM EDT SUN APR 26 2015

LINGERING LOW LEVEL MOISTURE AND COOLER AIRMASS BEHIND A SHORTWAVE
TROUGH THAT MOVED THROUGH SUN NIGHT WILL LEAD TO CLOUD COVER EARLY
MON OVER ESPECIALLY THE CENTRAL AND ERN CWA. THE CLOUD COVER WILL
SLOWLY DIMINISH AS THE SFC RIDGE MOVES BACK IN FROM THE W AS WELL AS
THE APPROACH OF AN UPPER RIDGE. CAN NOT COMPLETELY RULE OUT SOME
LIGHT DRIZZLE IN UPSLOPE AREAS OF NCENTRAL UPPER MI...BUT NOT ENOUGH
CONFIDENCE TO INCLUDE IN THE FORECAST. INTERIOR W SHOULD SEE HIGHS
APPROACH 60F ON MON...WHILE LAKESHORE AND ERN AREAS ARE QUITE A BIT
COOLER WITH HIGHS IN THE UPPER 30S TO THE UPPER 40S.

A COUPLE OF ROUNDS OF SHORTWAVE ENERGY WILL BREAK DOWN THE RIDGE TUE
EVENING AND AGAIN ON WED...WITH MODELS CURRENTLY SHOWING THE
STRONGER SHORTWAVE ON WED. MODELS HAVE NOT SHOWN GOOD CONTINUITY
WITH THESE FEATURES...SO CONFIDENCE IN EXACT DETAILS IS LOW.
HOWEVER...MODEL DO GENERALLY AGREE THAT MOISTURE WILL BE LIMITED
ENOUGH TO KEEP ANY SIGNIFICANT PRECIP FROM OCCURING. TUE WILL BE
WARMER THAN MON WITH HIGHS IN THE 50S AND 60S AS THE AIRMASS WILL BE
WARMER AND THE SHORTWAVE/CLOUD COVER DOES NOT ARRIVE UNTIL LATER IN
THE DAY. WED COULD SEE A SIGNIFICANT COOLER AIRMASS DEPENDING ON
DETAILS WITH THE SHORTWAVE...POSSIBLY RESULTING IN HIGH TEMPS IN THE
40S TO MID 50S.

UPPER RIDGING REPLACES THE SHORTWAVE ENERGY THU INTO FRI. MODELS
HAVE BEEN STRUGGLING WITH CONTINUITY IN THE STRENGTH OF THE
RIDGE...LIMITED CONFIDENCE SOME. HIGHS ON THU WILL BE IN THE 50S TO
MID 60S...WITH SIGNIFICANTLY WARMER HIGHS IN THE 60S TO LOW 70S ON
FRI. MODEL DISAGREEMENT AND DISCONTINUITY CERTAINLY CONTINUE AND
INCREASE ON SAT AS MODELS VARY VASTLY IN THE STRENGTH AND PLACEMENT
OF UPPER LEVEL ENERGY OVER CENTRAL CANADA. MODELS SHOW SOME
SHORTWAVE ENERGY MOVING ACROSS THE CWA WITH A WEAK SFC TROUGH LATE
FRI AND FRI NIGHT...WHICH COULD PRODUCE CONVECTION ACROSS THE CWA.
WILL CONTINUE SHOWING SLIGHT CHANCE POPS GIVEN UNCERTAINTY.
ADDITIONAL DIFFERENCE BETWEEN MODELS /ALSO TIED TO UNCERTAINTIES
WITH THE CENTRAL CANADA ENERGY/ WITH TEMPS ON SAT. THE 12Z/25 ECMWF
BRINGS AN AMPLIFIED UPPER RIDGE TO JUST W OF THE CWA BY 00Z SUN
WHILE THE 00Z/26 GFS HAS AN UPPER TROUGH WHERE THE ECMWF HAS THE
RIDGE. AIRMASS WILL BE A LOT WARMER UNDER THE ECMWF SOLUTION WITH
850MB TEMPS OF 12C BY 00Z SUN WHILE THE GFS IS AT 8C. WHILE
POTENTIAL FOR MUCH WARMER TEMPS EXISTS...CONFIDENCE IS LOW SO WILL
CONTINUE WITH A CONSENSUS APPROACH WITH HIGHS INT HE 60S AND 70S
AWAY FROM THE IMMEDIATE LAKESHORE.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 132 PM EDT SUN APR 26 2015

AS MORE LLVL MSTR ARRIVES FM THE NE TNGT IN THE PRESENCE OF
NOCTURNAL COOLING...EXPECT LO CLDS TO IMPACT MAINLY CMX AND
ESPECIALLY SAW...WHERE THE EXPECTED NNE WIND WL HAVE THE SHARPER
UPSLOPE COMPONENT. IFR CIGS SHOULD OCCUR AT SAW FOR A NUMBER OF HRS
LATE TNGT THRU MUCH OF MON MRNG. IFR CONDITIONS AT CMX WL ALSO BE
PSBL...BUT MAINTAINED PREVIOUS FCST LO MVFR RANGE CONDITIONS FOR
NOW. IWD MAY ALSO SEE SOME LO CLDS/MVFR CIGS...BUT DOWNSLOPE WIND
COMPONENT AND LOCATION OF WRN EDGE OF THE MORE SGNFT MSTR JUSTIFY
ONLY A SCT SKY FCST ATTM. SAW WL SEE THE SLOWEST IMPROVEMENT ON
MON...WITH VFR CONDITIONS NOT LIKELY THERE UNTIL AFTER THE END OF
THIS FCST PERIOD.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 507 AM EDT SUN APR 26 2015

WITH SFC HIGH PRES RIDGING S THRU WRN LAKE SUPERIOR TODAY THRU
MON...WINDS WILL BE LIGHTEST OVER WRN LAKE SUPERIOR...MOSTLY UNDER
15KT. OVER THE E...WINDS WILL OCCASIONALLY GUST TO 20-25KT. THE
RIDGE WILL WEAKEN TUE AND GIVE WAY TO LOW PRES TROF PASSAGE TUE
NIGHT. IN ITS WAKE...ANOTHER HIGH PRES WILL RIDGE S FROM HUDSON BAY
INTO THE UPPER GREAT LAKES WED/THU. WITH PRES GRADIENT ON THE WEAK
SIDE...WINDS TUE THRU THU SHOULD BE UNDER 15KT ACROSS LAKE SUPERIOR
THOUGH THERE MAY BE SOME STRONGER WINDS ON WED AS THE HIGH BEGINS
RIDGING S INTO THE UPPER LAKES.
&&

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

$$

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


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