Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 191118
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
718 AM EDT TUE MAY 19 2015

.AVIATION...

EXTENSIVE STRATUS/STRATOCU WILL ENCOMPASS SE MICHIGAN TODAY AS
COLDER AIR COMBINES WITH DAYTIME HEATING.  CEILING HEIGHTS WILL
LARGELY HOVER WITHIN THE 2500 TO 3500 FT RANGE...TENDING TO RISE BY
THE LATTER HALF OF THE DAY.  A GUSTY NORTHWEST THROUGH THE DAYLIGHT
PERIOD.  PEAK GUSTS INTO THE 25 KNOT RANGE.  SLOW REDUCTION IN CLOUD
COVERAGE THROUGH THE FIRST HALF OF THE NIGHT.  GUSTY CONDITIONS WILL
SUBSIDE WITH THE LOSS OF HEATING THIS EVENING.

//DTW THRESHOLD PROBABILITIES...

* HIGH FOR CEILING AOB 5000 FEET TODAY.

&&

.PREV DISCUSSION...ISSUED 343 AM EDT TUE MAY 19 2015

SHORT TERM...TODAY AND TONIGHT

MID LEVEL TROUGH NOW LIFTING THROUGH WISCONSIN WILL SWEEP ACROSS
LOWER MICHIGAN THROUGH THE FIRST HALF OF TODAY.  ONGOING SFC-925 MB
COLD AIR ADVECTION WILL DEEPEN THIS MORNING AS A TRAILING 850 MB
FRONT MOVES THROUGH...850 MB TEMPERATURES FALLING TO WITHIN A COUPLE
DEGREE OF 0C BY THIS EVENING.  EXTENSIVE PLUME OF LOW LEVEL MOISTURE
TIED TO THE ADVECTIVE PROCESS WILL LOCK INTO DAYTIME HEATING AND THE
INCREASING LAPSE RATES...RESULTING IN A BROAD STRATUS/STRATOCU FIELD
TODAY.  MOISTURE DEPTH APPEARS INADEQUATE TO SUPPORT LIGHT RAIN
DEVELOPMENT.  TEMPERATURE RECOVERY WILL BE CAPPED BY BOTH THE LACK
OF GREATER INSOLATION AND THE ONGOING CAA.  HIGH TEMPERATURE
DISTRIBUTION RANGING FROM MID 50S NORTH TO LOWER 60S SOUTH.  A FIRM
INCREASE IN NORTHWEST FLOW AS COLDER AIR SPILLS IN WILL PROVIDE A
NOTED UPTICK IN GUSTINESS AS GREATER MIXING EVOLVES THROUGH THE DAY.
LATEST SOUNDINGS SUGGEST SOME PEAK GUSTS INTO THE 25 TO 30 MPH
RANGE.

GRADUAL REDUCTION IN CLOUD COVERAGE THROUGH EARLY TONIGHT AS STEADY
MID LEVEL DRYING AND OVERALL SUBSIDENCE WORKS INTO THE SHRINKING
MOIST LAYER TUCKED BENEATH THE INVERSION.  NORTHWEST GRADIENT WILL
BE SLOWER TO DIMINISH...CASTING SOME DOUBT AS TO THE DEGREE OF
COOLING AND PROSPECTS FOR FROST OVERNIGHT.  STRENGTH OF THIS AIR
/925 MB TEMPS OF -2C/ WILL LARGELY SUPPORT LOW TEMPERATURE READINGS
OF MIDDLE AND UPPER 30S.  WILL CONTINUE TO HIGHLIGHT THE POTENTIAL
FOR PATCHY FROST...BUT MODEL PROJECTIONS OF A PERSISTENT 4-6 KNOT
NORTHWEST WIND WOULD SUGGEST A GREATER COVERAGE/IMPACT OF FROST
FORMATION IS CONSIDERABLY LOWER IN PROBABILITY.  THIS WILL PRECLUDE
A FROST HEADLINE ISSUANCE AT THIS TIME.

LONG TERM...WEDNESDAY THROUGH MONDAY

QUIET WEATHER IS EXPECTED INTO THE FIRST HALF OF THE WEEKEND. A LOW
PRESSURE SYSTEM WILL THEN BRING A CHANCE FOR RAIN AND THUNDERSTORMS
SUNDAY AND MONDAY.

A WEAK UPPER TROUGH IS FORECAST BY MODELS TO WORK ACROSS THE OHIO
VALLEY WEDNESDAY NIGHT. NAM/EURO SHOW MID-LEVEL DEFORMATION AXIS AND
MOISTURE JUST BRUSHING THE SOUTHERN PORTION OF THE FORECAST AREA
(SOUTH OF I-94)...WHILE OTHER MODELS KEEP FORCING/MOISTURE FURTHER
TO OUR SOUTH. EVEN IF THE MOISTURE DOES MAKE IT UP INTO
MICHIGAN...IT WILL ENCOUNTER A VERY DRY AIRMASS PUT IN PLACE BY THE
PASSAGE OF A STRONG COLD FRONT LAST NIGHT. WILL RETAIN ONLY VERY LOW
POPS CLOSE TO THE OHIO BORDER.

ENERGY OFF THE NORTHWEST COAST OF GREENLAND WILL THEN DROP INTO
HUDSON BAY ON WEDNESDAY...AND INTO NORTHWEST QUEBEC THURSDAY. THIS
WILL PUSH A WEAK SURFACE TROUGH DOWN INTO THE CENTRAL GREAT LAKES
WEDNESDAY NIGHT INTO THURSDAY...AND PUSH A WEAK COLD FRONT DOWN INTO
MICHIGAN THURSDAY/THURSDAY NIGHT. FORECAST REMAINS DRY FOR THIS AS
MOISTURE WILL BE LACKING.

SURFACE HIGH PRESSURE WILL THEN SETTLE IN FOR THE END OF THE
WEEK...KEEPING THE FORECAST DRY FRIDAY AND SATURDAY. EURO/GFS TRACK
AN AREA OF LOW PRESSURE UP TOWARDS THE GREAT LAKES FOR THE BEGINNING
OF NEXT WEEK. THEY HAVE BEEN SHOWING THIS FOR SEVERAL DAYS NOW...BUT
SOLUTIONS HAVE DIFFERED WIDELY WITH THE EVOLUTION OF THE LOW. THIS
LEADS TO LOW CONFIDENCE WITH THE DETAILS AND WILL OPT TO KEEP POPS
ONLY IN THE CHANCE CATEGORY.

TEMPERATURES THROUGH THE EXTENDED WILL REMAIN BELOW NORMAL WEDNESDAY
INTO THURSDAY...BEFORE MODERATING FOR THE END OF THE WEEK.

MARINE...

NORTHWEST FLOW WILL STRENGTHEN TODAY AND TONIGHT AS COLDER AIR POURS
INTO THE REGION BEHIND A COLD FRONT. SPEEDS WILL BE STRONGEST OVER
LAKE HURON WHERE GUSTS TO 30 KNOTS ARE POSSIBLE THROUGH TONIGHT. THE
PERSISTENCE OF STRONG NORTHWEST WINDS WILL CAUSE WAVE HEIGHTS TO
BUILD IN EXCESS OF 4 FEET TONIGHT OVER THE NEARSHORE WATERS OF LAKE
HURON BETWEEN PORT AUSTIN AND PORT SANILAC...AND OVER OUTER SAGINAW
BAY. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THESE AREAS. WIND
SPEEDS WILL DECREASE ON WEDNESDAY AS HIGH PRESSURE BUILDS INTO THE
AREA.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 10 AM EDT WEDNESDAY
     FOR LHZ421-441-442.

LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
&&

$$

AVIATION.....MR
SHORT TERM...MR
LONG TERM....HLO
MARINE.......HLO


YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).



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