Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 260801
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
401 AM EDT SUN APR 26 2015

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 145 PM EDT SAT APR 25 2015

THE SFC RIDGE OF HIGH PRESSURE EXTENDING DOWN FROM W HUDSON BAY AND
N CANADA WILL SHIFT ITS AXIS WESTWARD TONIGHT TO W ONTARIO AND
MN...BEFORE SLOWLY BUILDING BACK OVERHEAD SUNDAY. UNDER A MOSTLY
CLEAR SKY WITH LIGHT WINDS AND PW VALUES NEAR 0.25-0.3IN OVER THE W
HALF...WILL LOWER TEMPS SLIGHTLY IN THE TRADITIONAL COOL SPOTS.

AT 500MB...COINCIDING WITH THE RETROGRADING SFC RIDGE...WE/LL SEE
THE 500MB LOW SET UP ACROSS THE ME COAST SINK THE E-W ORIENTED
TROUGH SET UP THROUGH CENTRAL ONTARIO DOWN ACROSS MUCH OF THE UPPER
GREAT LAKES REGION THROUGH SUNDAY. THE MAIN THREAT WILL BE CLOUD
COVER...AS THE THICK CLOUDS TO THE NE NEAR. THE INITIAL QUICKLY
ADVANCING MVFR CEILINGS ARE MOVING SSW AROUND 16KTS. WILL CONTINUE
TO MONITOR THE SSE PROGRESSION...AS MODELS CONTINUE TO HINT AT SOME
OF THOSE CLOUDS MOVING ACROSS THE LAKE AND INTO THE N CENTRAL/E CWA
OVERNIGHT. ASSISTED BY UPSLOPE N WINDS...THE BEST CHANCE FOR THE
LOWER CLOUDS WILL BE FROM BARAGA THROUGH MQT AND ALGER COUNTIES.
WILL CONTINUE TO MONITOR FOR THIS POTENTIAL. OTHERWISE...DAYTIME
MIXING SHOULD LIFT/MIX OUT THE CLOUDS BACK TO SCATTERED OR
BORDERLINE BROKEN DURING THE EARLY AFTERNOON HOURS. LOOK FOR A
TEMPORARY BREAK FROM THE THICK CLOUDS AS MORE NEAR FROM ONTARIO.
HIGHS WILL BE SIMILAR TO TODAY..AND POSSIBLY A BIT COOLER TOMORROW
ALONG LAKE SUPERIOR GIVEN THE STEADY N WINDS.

.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 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 138 AM EDT SUN APR 26 2015

A RIDGE OF HIGH PRESSURE OVER CENTRAL LAKE SUPERIOR WILL SLOWLY
SHIFT WEST OVER THE MINNESOTA ARROWHEAD TODAY. THIS WILL LEAD TO
PERSISTENT NORTHERLY FLOW AT ALL THREE TAF SITES UNDER VFR
CONDITIONS. THE MAIN CONCERN IS THE POTENTIAL FOR MVFR CLOUDS TO
DEVELOP UNDER THE LOW LEVEL NORTH-NORTHEASTERLY FLOW EARLY THIS
MORNING AND INTO THE DAY AT KSAW AND MAYBE KCMX. SINCE THE LOW
CLOUDS IN NORTHERN ONTARIO HAVE STRUGGLED TO EXPAND THUS FAR AND
MODELS ARE TRENDING DRIER...OPTED TO BACK AWAY FROM THE MVFR CEILINGS
AT KSAW FOR EARLY THIS MORNING THROUGH EARLY AFTERNOON. HAVE STILL
KEPT SCT CLOUDS FOR THAT PERIOD...BUT CONFIDENCE IS LOW.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 145 PM EDT SAT APR 25 2015

THE LINGERING NE FLOW OVER FAR W LAKE SUPERIOR WILL KEEP SOME GUSTS
OF 20-30KTS THERE THIS AFTERNOON...OTHERWISE WINDS WILL BE GUSTING
TO 25KTS OR LESS THROUGH THE PERIOD. A RIDGE OF HIGH PRESSURE ACROSS
LAKE SUPERIOR WILL STRENGTHEN AND FOCUS JUST TO THE WEST
/ACROSS W ONTARIO AND MN/ SUNDAY MORNING THROUGH SUNDAY EVENING. THE
RIDGE WILL THEN AGAIN SLIDE MORE ACROSS LAKE SUPERIOR MONDAY INTO
TUESDAY. A WEAK TROUGH OF LOW PRESSURE SYSTEM CROSSING INTO W
ONTARIO AND MN TUESDAY MORNING WILL BRIEFLY WEAKEN THE RIDGE. HIGH
PRESSURE WILL RETURN FOR THE MIDDLE TO END OF THE WORK WEEK
WEEK...EXTENDING FROM MANITOBA THROUGH THE CENTRAL PLAINS TUESDAY
AFTERNOON...AND CROSSING INTO THE UPPER GREAT LAKES FROM WEDNESDAY
ON.
&&

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

$$

SHORT TERM...KF
LONG TERM...TITUS
AVIATION...SRF
MARINE...KF


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