Area Forecast Discussion
Issued by NWS Marquette, MI

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497
FXUS63 KMQT 170810
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
410 AM EDT SUN MAY 17 2015

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 306 PM EDT SAT MAY 16 2015

UPPER AIR PATTERN CONSISTS OF A CLOSED 500 MB LOW OVER CENTRAL
ROCKIES WITH A DEEP TROUGH OVER THE ROCKIES AND A SHORTWAVE RIDGE
OVER THE UPPER MISSISSIPPI RIVER VALLEY. THE RIDGE MOVES INTO THE
UPPER GREAT LAKES BY THIS EVENING WITH THE TROUGH MOVING INTO THE
WESTERN HIGH PLAINS. THE TROUGH MOVES INTO THE UPPER MISSISSIPPI
RIVER VALLEY ON SUNDAY WITH THE RIDGE MOVING INTO THE LOWER GREAT
LAKES.

NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE INTO THE AREA
LATE TONIGHT WITH SOME DEEPER MOISTURE ARRIVING SUNDAY MORNING WHICH
REMAINS THROUGH ALL OF SUNDAY. GFS AND ECMWF SHOW ABOUT THE SAME
THING AS WELL.

FORECAST HINGES ON HOW MUCH LOW LEVEL MOISTURE IS AROUND LATE
TONIGHT AND HOW MUCH INSTABILITY AND SUNSHINE THAT WE WILL SEE ON
SUNDAY. THERE IS PLENTY OF LOW LEVEL MOISTURE AROUND AS THERE WAS
FOG THIS MORNING OVER PARTS OF THE AREA AND FOG ON LAKE MICHIGAN AND
LAKE SUPERIOR WHICH DOES PROVIDE A LOCAL MOISTURE SOURCE. WITH
SOUTHEAST TO EAST LOW LEVEL FLOW TONIGHT...STRATUS AND FOG WILL
DEVELOP AGAIN LATER TONIGHT. WITH HIGHER CLOUDS COMING IN SUNDAY
MORNING FROM CONVECTION OFF TO THE WEST AND SOUTH OF THE AREA...THE
STRATUS WILL HAVE A HARDER TIME BURNING OFF SUN MORNING AND THERE
WILL BE MORE CLOUD COVER AROUND WHICH SHOULD DECREASE THE
INSTABILITY A BIT. DIURNAL HEATING OCCURS SUNDAY AFTERNOON AND
INCREASE POPS LATER IN THE AFTERNOON AS UPPER TROUGH GETS CLOSER AND
HAVE LIKELY POPS IN THE WEST HALF AND CHANCE POPS ACROSS THE EAST
HALF. AGREE WITH MARGINAL SEVERE RISK FOR CWA WITH SLIGHT TO THE
SOUTHWEST OF THE AREA FOR SUNDAY. OVERALL...DID NOT MAKE TOO MANY
CHANGES TO THE GOING FORECAST AND KEPT IT DRY UNTIL LATE TONIGHT IN
THE WEST WHERE HAVE SLIGHT CHANCE POPS LATE.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 407 AM EDT SUN MAY 17 2015

AS HAS BEEN TALKED ABOUT FOR SEVERAL DAYS...SPLIT FLOW WILL PERSIST
ACROSS THE CONTINENT FOR THE FORESEEABLE FUTURE...WITH STRONG
POSITIVE HEIGHT ANOMALIES ACROSS NW CANADA. THIS SHOULD KEEP THE
UPPER GREAT LAKES IN STRONGLY CONFLUENT FLOW FOR MUCH OF THE
FORECAST PERIOD BEYOND TUESDAY...YIELDING A DRY FORECAST INTO
MEMORIAL DAY WEEKEND.

AS FOR MONDAY...THE NWP ARE IN GOOD AGREEMENT IN SHOWING THE
OCCLUDED FRONT MOVING ACROSS THE AREA DURING THE MORNING HOURS. WITH
THE AREA BEING IN THE DRY SLOT IN THE MORNING AND STRONG
MID LEVEL Q-VECTOR DIVERGENCE...EXPECT ANY PRECIPITATION TO BE
CONFINED TO NEAR LAKE MICHIGAN WHERE MOIST ONSHORE FLOW WILL KEEP
CHANCES OF DRIZZLE/FOG IN THE MORNING HOURS BEFORE THE WINDS TURN
WESTERLY. BEHIND THE FRONT...COMMA HEAD MOISTURE WILL ATTEMPT TO
WRAP INTO THE AREA...BUT THE DEEPER MOISTURE WILL REMAIN OVER FAR
WESTERN LAKE SUPERIOR INTO MINNESOTA UNTIL LATE IN THE DAY INTO THE
OVERNIGHT HOURS. COULD BE A PASSING SHOWER MONDAY AFTERNOON ACROSS
THE WEST AND KEWEENAW AS THE DEEPER MOISTURE WRAPS IN BEHIND THE
FILLING AREA OF LOW PRESSURE AND INCREASING UPSLOPE FLOW DUE TO NW
WINDS. STRONG COLD ADVECTION AS THE UPPER TROUGH MOVES EAST OF THE
AREA WILL ALLOW FOR 850MB TEMPS TO DROP TO -9C ACROSS MUCH OF THE
AREA. THIS COMBINED WITH NW FLOW WILL ALLOW FOR ANY RAIN SHOWERS TO
CHANGE TO SNOW AND PERHAPS INCREASE IN AREAL COVERAGE ACROSS THE
WESTERN PART OF UPPER MICHIGAN. DUE TO THE COLD TEMPERATURES AND
PRECIPITATION OCCURING DURING THE OVERNIGHT HOURS...COULD NOT
TOTALLY RULE OUT A DUSTING TO LOCALLY AN INCH OVER GRASSY AREAS
MONDAY NIGHT INTO TUESDAY MORNING BUT GIVEN THE LACK OF SIGNIFICANT
SYNOPTIC SUPPORT DUE TO THE BEST UPPER ENERGY REMAINING WEST AND
NORTH OF THE AREA...DO NOT EXPECT ANY MORE THAN THAT AT THIS TIME.
COLD AND WINDY DAY ON TUESDAY WITH DRYING ACROSS THE ENTIRE AREA
LIKELY CAUSING ANY PRECIPITATION NEAR LAKE SUPERIOR TO SUBSIDE
DURING THE AFTERNOON HOURS.  STILL...IT WILL BE QUITE RAW WITH
TEMPERATURES 15-20 DEGREES BELOW NORMAL.

HEIGHTS BEGIN TO RISE ON WEDNESDAY AS THE UPPER RIDGE OVER THE
WRN ATLC BREAKS DOWN SLIGHTLY...ALLOWING THE LONG WAVE TROUGH OVER
THE REGION TO SHIFT EAST. THIS WILL ALLOW FOR SOME MODEST WARMING AT
850MB TO +4C BY WED EVENING ...WHICH COMBINED WITH THE SUNSHINE
SHOULD ALLOW FOR TEMPS TO GET AT LEAST INTO THE 50S OR LOWER 60S ON
WEDNESDAY....BUT STILL BELOW NORMAL FOR THIS TIME OF YEAR. CONTINUED
WARMING ON THURSDAY AHEAD OF AN UPPER DISTURBANCE ROTATING AROUND
THE UPPER LOW OVER NW QUEBEC. THE GFS AND ECMWF SUGGEST THIS UPPER
DISTURBANCE WILL CLIP THE UPPER GREAT LAKES THU NIGHT...HOWEVER
GIVEN THE VERY DRY AIRMASS IN PLACE ACROSS THE REGION NO
PRECIPITATION IS EXPECTED. WILL GO WITH SLIGHTLY COOLER TEMPS FRIDAY
AS 850MB TEMPS DROP BACK TO -1C. WARMER ON SATURDAY AND STILL DRY AS
HEIGHTS RISE ONCE AGAIN.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 135 AM EDT SUN MAY 17 2015

ALL SITES ARE CURRENTLY VFR...BUT A TRICKY FORECAST FOR
THE OVERNIGHT AND SUNDAY TIME PERIODS. STRATUS AND SOME FOG WILL
DEVELOP OVERNIGHT TONIGHT...ESPECIALLY AT SAW WITH UPSLOPE FLOW OFF
LAKE MICHIGAN AT SAW AND POSSIBLY AT KCMX WITH UPSLOPE EASTERLY FLOW
OFF LAKE SUPERIOR. STRATUS SHOULD EVEN MAKE IT TO IWD LATE TONIGHT.
LOW CEILINGS SHOULD MIX OUT AT CMX AND MAYBE EVEN IWD DURING THE DAY
TOMORROW BUT PERSISTENT UPSLOPE FLOW WILL KEEP LOW CLOUDS AT SAW FOR
MUCH OF THE DAY. SHOWER AND ISOLATED THUNDER CHANCES WILL INCREASE
FROM WEST TO EAST THROUGH THE DAY.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 306 PM EDT SAT MAY 16 2015

AREAS OF FOG WILL CONTINUE INTO SUNDAY NIGHT ACROSS THE GREAT LAKES
AS HUMID AIR MOVES ACROSS THE COLDER WATER AND WILL CONTINUE WITH
THE DENSE FOG ADVISORY FOR THE LAKE MICHIGAN ZONES THROUGH SUNDAY
NIGHT BEFORE COLDER AND DRIER AIR MOVES IN MON MORNING. AS FOR LAKE
SUPERIOR...FOG WILL EXPAND AGAIN TONIGHT WITH LOSS OF HEATING AND
HAVE AREAS OF FOG DEVELOPING IN THE LAKE. WIND GUSTS UP TO 30 KNOTS
ARE POSSIBLE MON NIGHT INTO TUE WITH COLD AIR MOVING ACROSS THE LAKE
AND COULD SEE A FEW GALE FORCE GUSTS WITH THAT...OTHERWISE NO GALES
SEEN.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
  DENSE FOG ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR LMZ248-
     250.

&&

$$

SHORT TERM...07
LONG TERM...MRD
AVIATION...MZ
MARINE...07



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