Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 220751
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
350 AM EDT WED OCT 22 2014

.SHORT TERM...TODAY AND TONIGHT

SOUTHEAST MICHIGAN HOLDING FIRM THIS MORNING WITHIN THE EXISTING MID
LEVEL CYCLONIC FLOW ATTENDANT TO THE OUTER PERIPHERY OF THE
SPRAWLING CLOSED MID LEVEL CIRCULATION POSITIONED OVER THE MID
ATLANTIC COASTLINE.  RETENTION OF A MODESTELY DEEP NORTH-NORTHEAST
GRADIENT UNDER THIS PATTERN SUSTAINING AT LEAST A WEAK COLD AIR
ADVECTIVE COMPONENT...AND LIKELY PROVIDING SOME DEGREE OF MOISTURE
FLUX CONTRIBUTION OFF LAKE HURON.  THE NET RESULT EARLY THIS MORNING
BEING THE SOLIDIFICATION AND RENEWED WESTWARD EXPANSION OF STRATUS
ACCOMPANYING THIS COOLING/MOISTENING OF THE SUB-INVERSION LAYER.
LATEST SOUNDING ANALYSIS AND LOW LEVEL RH FIELDS CONTINUE TO SUGGEST
THE EXTENSIVE DRY LAYER EXISTING AT THE EDGE OF BUILDING HIGH
PRESSURE JUST UPSTREAM WILL TAKE SOME TIME TO MAKE BETTER INROADS
LOCALLY TODAY.  THIS POINTS TO A MOSTLY CLOUDY FIRST HALF OF THE
DAY...BEFORE INCREASING SUBSIDENCE AND DRY AIR ADVECTION AIDES IN A
PROGRESSIVE CLEARING TREND DURING THE AFTERNOON.  HIGHS TODAY IN THE
LOWER AND MIDDLE 50S.

HIGH PRESSURE DOMINATED CONDITIONS EXPECTED TONIGHT.  A DIMINISHING
GRADIENT FLOW...CLEAR SKY...AND DRY MID LEVEL ENVIRONMENT CONTINUE
TO LEND CONFIDENCE TOWARD WITNESSING A STRONG RADIATIONAL COOLING
RESPONSE OVERNIGHT.  LOWS MAKING A RUN INTO THE UPPER 20S IN THE
COLDEST LOCALES.

&&

.LONG TERM...THURSDAY THROUGH TUESDAY

THURSDAY WILL START WITH RIDGING AT THE SURFACE AND ALOFT OVER
SOUTHEAST MICHIGAN. THIS SHOULD MAINTAIN QUIET AND DRY CONDITIONS
OVER THE AREA. SUNSHINE AND WEAK THERMAL ADVECTION (H850 TEMPS UP TO
8C) WILL HELP BOOST TEMPERATURES INTO THE MID 50S. MODELS THEN
CONTINUE TO SHOW SOME MINOR DIFFERENCES WITH HOW THEY HANDLE ENERGY
WITHIN THE UPPER TROUGH NOW SEEN ON WATER VAPOR STRETCHING FROM THE
CANADIAN ROCKIES DOWN TOWARDS THE FOUR CORNERS. NAM IS A FAST
OUTLIER WITH THE ENERGY INTO THE GREAT LAKES...WHILE THE EURO/GEM
NOW SPLIT THE ENERGY...TAKING THE BIGGER PIECE DOWN INTO THE
TENNESSEE VALLEY WHILE THE REST CROSSES MICHIGAN LATE THURSDAY NIGHT
AND FRIDAY. THESE SOLUTIONS CONTINUE TO SHOW MOST OF THE MOISTURE AT
THE MID AND UPPER LEVELS...AND SHOW LITTLE IN THE WAY OF A LOW-LEVEL
FORCING MECHANISM. THIS CONTINUES TO SUPPORT A DRY FORECAST WITH
JUST AN INCREASE IN CLOUDS...BUT WILL CONTINUE TO MONITOR MODEL
SOLUTIONS AND WATER VAPOR IMAGERY IN CASE CHANGES ARE WARRANTED.

MEDIUM-RANGE MODELS THEN CONTINUE TO SHOW STRONG CONTINUITY WITH A
LARGER UPPER LOW OVER THE GULF OF ALASKA DIVING THROUGH ONTARIO
FRIDAY NIGHT THROUGH SATURDAY NIGHT. INCREASED MIXING AHEAD OF A
COLD FRONT ASSOCIATED WITH THIS FEATURE SHOULD BOOST TEMPERATURES
CLOSER TO 60 ON SATURDAY...AS WE MIX INTO WARMER AIR ALOFT THAT
SHOULD ARRIVE LATE FRIDAY. DRY COLD FRONT IS THEN PROGGED TO DROP
THROUGH SATURDAY EVENING...BRINGING AN INCREASE IN WINDS AND
DROPPING TEMPERATURES BACK DOWN INTO THE 50S FOR SUNDAY.

GFS/EURO THEN IN STRONG AGREEMENT WITH UPPER RIDGING SLIDING OVER
THE AREA SUNDAY INTO MONDAY...CONTINUING THE STRETCH OF DRY WEATHER.
AN APPROACHING TROUGH SHOULD HOWEVER BOOST WIND SPEEDS ON
MONDAY...THEN BRING A CHANCE FOR SHOWERS ON TUESDAY.

&&

.MARINE...SHORELINE CONVERGENCE IS ADDING LOCAL EFFECTS TO THE
STRONG NORTHERLY WINDS IMPACTING THE SHORE ALONG SOUTHERN BASIN OF
LAKE HURON. FORT GRATIOT OBSERVATIONS HAVE SHOWN A SHORT DURATION OF
GALE FORCE WINDS THIS AFTERNOON. SUSPECT THERE IS NOT WIDESPREAD
GALE CRITERIA BEING REACHING GIVEN THE FACT THIS IS AN ELEVATED
SITING. WILL NOT BE MAKING ANY CHANGES TO THE HEADLINES FOR THE
NEARSHORE WATERS OF LAKE HURON INCLUDING SAGINAW BAY. PER LATEST
SURFACE OBSERVATIONS...DID INCLUDE SMALL CRAFT ADVISORIES FOR LAKE
ST CLAIR AND THE MICHIGAN WATERS OF LAKE ERIE THROUGH THIS EVENING.
WINDS AND LARGE WAVES WILL GRADUALLY DECREASE OVERNIGHT AS LOW
PRESSURE OVER THE EASTERN GREAT LAKES TRACKS EAST AND A RIDGE OF
HIGH PRESSURE BUILDS INTO THE WESTERN GREAT LAKES. THIS HIGH WILL
REMAIN OVERHEAD DURING THE MID-WEEK PERIOD...ALLOWING FOR CALMER
CONDITIONS.

FURTHER TO THE SOUTH...SLIGHTLY LOWER WIND SPEEDS ARE EXPECTED OVER
LAKE ST CLAIR AND FAR WESTERN LAKE ERIE TODAY...WITH GUSTS EXPECTED
TO TOP OUT BELOW 25 KNOTS.

&&

.AVIATION...ISSUED 1225 PM EDT TUE OCT 21 2014

COLD/MOIST CYCLONIC FLOW ACROSS THE LOWER PENINSULA WILL SUPPORT
CONTINUED EXTENSIVE MVFR STRATOCU FOR THE REMAINDER OF THE DAY. AS
DIURNAL MIXING INCREASES...PATCHY DRIZZLE WILL BE REPLACED BY WIND
GUSTS TO 20 KNOTS. DESPITE THE GRADUAL DEPARTURE OF THE BETTER
MOISTURE TO THE EAST TONIGHT...CONTINUED FLOW OFF OF LAKE HURON
SHOULD BE SUFFICIENT TO SUPPORT CONTINUED LOW CLOUDS THROUGH THE
NIGHT. THE DETROIT AREA AIRFIELDS WILL BE FURTHER REMOVED FROM THE
LAKE HURON INFLUENCE SO ALLOWED SOME CLEARING TOWARD 12Z.

//DTW THRESHOLD THREATS...

* HIGH CONFIDENCE IN CEILINGS BELOW 5000 FT.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.

LAKE HURON...
     SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
     HURON INCLUDING OUTER SAGINAW BAY...UNTIL 6 AM WEDNESDAY.

LAKE ST CLAIR...NONE.

MI WATERS OF LAKE ERIE...NONE

&&

$$

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

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



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