Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 020019
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
819 PM EDT FRI AUG 1 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 342 PM EDT FRI AUG 1 2014

A WELL DEFINED SHORTWAVE IS CURRENTLY SWIRLING OVER WRN LAKE
SUPERIOR/FAR WRN UPPER MI AS IT ROTATES AROUND AN UPPER LOW THAT IS
EAST OF JAMES BAY. THE SFC PATTERN IS VERY WEAK AS THE UPPER LEVEL
PATTERN REMAINS PRETTY STAGNANT. THESE WEAK WINDS HAVE ALLOWED FOR
GREAT LAKE BREEZE FORMATION TODAY WITH THE LAKE MICHIGAN AND LAKE
SUPERIOR BREEZE MEETING UP HALF WAY BETWEEN THE LAKES OVER THE ERN
HALF OF UPPER MI. ELSEWHERE...THE LAKE BREEZES ARE 20-30 MILES
INLAND. THE SHORTWAVE IS VERY EASY TO SEE EVEN ON VIS SAT SINCE
MOISTURE IS LIMITED ENOUGH TO ONLY HAVE SYNOPTIC CLOUDS DIRECTLY
ALONG THE FEATURE. IT ENDED UP BEING TOO DRY IN THE MID LEVELS THIS
AFTERNOON FOR CONVECTION TO DEVELOP /EXCEPT FOR A COUPLE SHOWERS
OVER MACKINAC COUNTY/...WHICH IS IMPRESSIVE GIVEN THE STRENGTH OF
THE SHORTWAVE AND LAKE BREEZES.

BEHIND THE SHORTWAVE TONIGHT...EXPECT ANOTHER QUIET NIGHT WITH
MOSTLY CLEAR SKIES. LIGHT WINDS DUE TO WEAK HIGH PRESSURE RIDGE
DEVELOPING OVER THE CWA WILL ALLOW LOWS TO ONCE AGAIN RANGE FROM
THE UPPER 40S TO LOWER 50S. WILL CONTINUE TO SHOW THE PATCHY GROUND
FOG.

PATTERN STARTS TO SHIFT A BIT TOMORROW AS A SHORTWAVE AND SFC COLD
FRONT MOVE TOWARD THE AREA...BUT WILL NOT BRING PRECIP TO THE CWA
PRIOR TO 00Z SUN. THE NAM SHOWS SOME QPF OVER INTERIOR W UPPER MI
SAT AFTERNOON...BUT GIVEN HOW DRY IT HAS BEEN AND THAT THE NAM HAS
BEEN SIGNIFICANTLY OVERDOING MOISTURE...CONTINUED TO LEAVE PRECIP
OUT OF THE FORECAST FOR SAT. 850MB TEMPS WILL BE A COUPLE OF DEGREES
WARMER ON SAT THAN THEY WERE TODAY...SO HAVE SFC TEMPS TOPPING OUT
IN THE UPPER 70S TO AROUND 80...EXCEPT COOLER ALONG THE SHORELINE
AREAS. DID LOWER DEW POINTS FROM PREVIOUS FORECAST TO A MINIMUM OF
AROUND 50F...WHICH RESULTS IN MID TO UPPER 30 PERCENT RH VALUES...AS
MODELS SHOW MIXING TO AROUND 750MB WHICH TAPS INTO A VERY DRY LAYER
BETWEEN 700MB AND 500MB /LAYER RH VALUES OF 10-15 PERCENT/. DEW
PT/RH VALUES MAY NEED TO BE LOWERED FURTHER.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 325 PM EDT FRI AUG 1 2014

THE LATTER PORTION OF THE WEEKEND BEGINS WITH AN UPPER LEVEL TROUGH
OVER THE GREAT LAKES REGION...AND A RIDGE ANCHORED FIRMLY OVER THE
WESTERN UNITED STATES. THIS PUTS UPPER MICHIGAN IN SOMEWHAT ZONAL
FLOW BEFORE A SHORTWAVE SWEEPS INTO ONTARIO SATURDAY AFTERNOON. THE
GFS/NAM ARE STILL PUSHING THE ASSOCIATED COLD FRONT THROUGH THE CWA
SLIGHTLY EARLIER THAN THE GEM/ECMWF. SHOULD THE FRONT COME IN
EARLIER AS THE GFS/NAM SUGGEST...EXPECT PRECIPITATION TO ENTER THE
WESTERN CWA BY ABOUT 9Z. SHOULD THE ECMWF/GEM SOLUTION BE
CORRECT...TIMING WILL BE SLIGHTLY LATER FOR PRECIPITATION...LIKELY
AROUND 12Z-15Z. WILL GO WITH A COMPROMISE FOR POPS TO RESOLVE THE
MINOR TIMING DIFFERENCES FOR NOW...THOUGH I LEAN MORE TOWARDS THE
SLOWER TIMING OF THE ECMWF/GEM.

AS FAR AS THUNDERSTORM POTENTIAL...BEST CHANCES LOOK TO BE EARLY
SUNDAY AFTERNOON WITH DAYTIME HEATING AS THE FRONT ROLLS THROUGH.
THE BEST INSTABILITY...AROUND 1500-2000 J/KG...LINGERS ALONG THE WI
BORDER. OTHERWISE...MOST OF THE WESTERN AND NORTH CENTRAL CWA SEES
AROUND 500 J/KG. THE ECMWF/GEM KEEP LOWER INSTABILITY ACROSS THE
EAST...LESS THAN 100 J/KG....BUT THE GFS BRINGS THE HIGHER
INSTABILITY OF AROUND 1500 J/KG INTO THE INLAND EAST...AND GENERATES
CONVECTION ALONG THE LAKE BREEZE BOUNDARY. WILL KEEP SCHC THUNDER IN
THAT AREA FOR NOW GIVEN THE DISCREPENCY. AS FAR AS SHEAR
GOES...0-6KM FOR MOST OF THE CWA IS AROUND 15-20 KNOTS...SO WOULD
NOT BE SURPRISED TO SEE A COUPLE STRONGER STORMS DEVELOP IF THE
FRONT PASSES THROUGH WHEN THE BEST INSTABILITY IS IN PLACE.
THUNDERSTORM POSSIBILITY ENDS WITH DAYTIME HEATING...BUT WILL KEEP
CHANCES FOR PRECIPITATION IN THE EAST WITH THE PASSING FRONT...AGAIN
GOING WITH THE CONSENSUS FOR POPS GIVEN THE DISCREPANCIES BETWEEN
NAM/GFS AND THE ECMWF/GEM.

MONDAY THE RIDGE BUILDING ACROSS THE WESTERN CONUS AND CANADIAN
PRAIRIE WILL EXPAND INTO THE WESTERN CWA...WITH SURFACE HIGH
PRESSURE FORCING ITS WAY INTO UPPER MI. MODELS ALSO DEVELOP A LOW
PRESSURE SYSTEM OVER NEBRASKA/SOUTH DAKOTA THAT DRAPES A WARM FRONT
ACROSS WI AND IOWA. MODEL DIFFERENCES AGAIN BRING COMPLICATION TO
THE FORECAST...WITH THE GFS/GEM HAVING STRONGER SURFACE HIGH
PRESSURE THAT KEEPS THE LOW/WARM FRONT FURTHER SOUTH...AND ALL
PRECIPITATION ONLY UP TO THE WI BORDER. THE ECMWF BRINGS THE LOW AND
WARM FRONT FURTHER NORTH...AND GENERATES CONVECTION MONDAY AFTERNOON
INTO SOUTHERN UPPER MI. WILL KEEP GOING SLIGHT CHANCE POPS/CONSENSUS
FORECAST NEAR THE WI BORDER/SOUTH CENTRAL U.P. FOR NOW.

STRONG SFC HIGH PRESSURE CENTERS ITSELF OVER THE GREAT LAKES FOR
TUESDAY AND LINGERS OVER THROUGH WEDNESDAY...THOUGH AT UPPER LEVELS
THE TROUGH STILL LINGERS AND KEEPS 850MB TEMPS AROUND 10-12C. THIS
WILL KEEP THINGS A BIT COOLER THAN NORMAL...ESPECIALLY WITH LIGHT
WINDS ALLOWING FOR LAKE BREEZE DEVELOPMENT. OVERALL...EXPECT A DRY
FORECAST FOR THESE DAYS WITH HIGHS IN THE UPPER 60S NEAR THE
LAKE...AND THE LOW TO MID 70S INLAND.

IN THE MEANTIME...A POTENT 500MB SHORTWAVE DEVELOPS OVER THE
CANADIAN PRAIRIES WEDNESDAY MORNING DIGS DEEPER INTO THE NORTHERN
PLAINS BY WEDNESDAY EVENING. THIS AMPLIFIES THE RIDGE AND SHIFTS IT
EASTWARD FROM THE UPPER MISSISSIPPI VALLEY WEDNESDAY INTO UPPER
MICHIGAN FOR THURSDAY. SFC LOW PRESSURE DEVELOPS WITH THIS
SHORTWAVE...THOUGH THE ECMWF/GFS ONCE AGAIN DIFFER ON THE PLACEMENT
AND MOVEMENT OF THIS LOW. THE GFS DEVELOPS IT OVER THE NORTHERN
PLAINS AND MOVES IT INTO ONTARIO...AND THE ECMWF DEVELOPS IT OVER
IOWA AND MOVES IT INTO WISCONSIN. WILL STICK WITH CONSENSUS POPS YET
AGAIN THURSDAY INTO FRIDAY DUE TO THE LARGE DIFFERENCES.
&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 818 PM EDT FRI AUG 1 2014

VFR CONDITIONS ARE EXPECTED TO PREVAIL AT ALL THREE TAF SITES OVER
THE NEXT 24 HOURS.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 342 PM EDT FRI AUG 1 2014

WITH A WEAK PRESSURE GRADIENT TYPICAL OF SUMMER DOMINATING THIS
FORECAST PERIOD...EXPECT WINDS UNDER 15 KTS THROUGH TUE. ALTHOUGH
THERE WILL BE PATCHY FOG WITH RELATIVELY HUMID AIR OVER THE CHILLY
LAKE WATERS INTO MON...NO WIDESPREAD DENSE FOG IS LIKELY.
&&

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

$$

SHORT TERM...TITUS
LONG TERM...MCD
AVIATION...VOSS
MARINE...TITUS






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