Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 252247
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
647 PM EDT TUE AUG 25 2015


.AVIATION...

APPEARS TO BE SUFFICIENT DRY AIR NEAR THE SURFACE TO PREVENT
SIGNIFICANT LOWERING OF CIGS OVERNIGHT. INSTEAD EXPECT BORDERLINE
MVFR TO PERSIST WELL INTO WEDNESDAY WITH SOME IMPROVEMENT TO LOW VFR
BY WED AFTN. WITH NO STRONG SIGNAL FOR BACKING WINDS OR BUILDING
HIGH PRESSURE, STRATUS WILL PERSIST THROUGH THE FORECAST PERIOD.
WINDS WILL REMAIN 6-10KTS OUT OF THE NW QUADRANT.

FOR DTW...CEILINGS ARE EXPECTED TO REMAIN BKN-OVC BELOW 5KFT THROUGH
THE FORECAST PERIOD. SOME POTENTIAL FOR A BREAKOUT ON WED AFTN, BUT
APPEARS UNLIKELY GIVEN EXTENSIVE COVERAGE ON VISIBLE, AGGRESSIVE
MODEL PROGS, AND SIMPLE PATTERN RECOGNITION OF STRATUS BEHAVIOR
WITHIN COLD AIR. WILL MAINTAIN OVC UNTIL OBSERVATIONAL EVIDENCE
SUGGESTS OTHERWISE.


//DTW THRESHOLD PROBABILITIES...

* HIGH FOR CIGS AOB 5KFT UNTIL AT LEAST WEDNESDAY NIGHT

&&

.PREV DISCUSSION...ISSUED 344 PM EDT TUE AUG 25 2015

SHORT TERM...TONIGHT

LARGE CUT OFF LOW JUST SOUTH OF HUDSON BAY WILL CONTINUE THE FALL
LIKE WEATHER OVER THE GREAT LAKES.  PLENTY OF LOW LEVEL MOISTURE
WRAPPED AROUND THIS LOW IS PRODUCING LARGE STRATUS DECK OVER THE
GREAT LAKES.  LIGHT SHOWERS AND SPRINKLES DEVELOPED TODAY FROM
COMBINATION OF DIURNAL HEATING...WEAK MID LEVEL IMPULSES FALL LIKE
LAKE EFFECT FROM LAKE MICHIGAN AND SURFACE TROUGH.  MOST
CONCENTRATION OF PRECIP IS ALONG AND AHEAD OF THE SURFACE TROUGH NOW
PUSHING THROUGH FAR EASTERN METRO DETROIT. A FEW BRIEF VERY LIGHT
SHOWERS OR SPRINKLES ARE STILL POSSIBLE WITH WHAT LITTLE CAPE THERE
IS BEFORE SUNSET.  AFTER EXPECT A MOSTLY OVERCAST STRATUS DECK FOR
THE NIGHT.  HIGHS THIS AFTERNOON FELL ABOUT 15 DEGREES SHORT OF
THE AVERAGES WHICH FOR THIS TIME OF YEAR IS AROUND 80.  LOWS
TONIGHT MAINLY LOW TO MID 50S

LONG TERM...

UPPER LEVEL TROUGH AXIS WILL SLOWLY CLEAR THE CENTRAL GREAT LAKES
TOMORROW...BUT ONE MORE TRAILING SHORTWAVE COMING DOWN COUPLED WITH
THE LINGERING LOW LEVEL CYCLONIC COLD AIR (850 MB TEMPS OF 6 C) WILL
PROBABLY BE SUFFICIENT TO GENERATE ISOLATED SHOWERS. ABUNDANT CLOUD
COVER (PER 850 MB RH FIELDS) TO CAP MAXES AROUND 70 DEGREES.

UPPER LEVEL RIDING BUILDING INTO LOWER MICHIGAN WEDNESDAY NIGHT INTO
THURSDAY...WITH SURFACE 1020-1022 MB SURFACE HIGH ARRIVING ON
THURSDAY. HOWEVER...STILL CONCERN WITH SOME RESIDUAL LOW LEVEL
MOISTURE LINGERING...WITH POSSIBLE SUFFICIENT CU UP ON THURSDAY TO
SUPPORT PARTLY SUNNY FORECAST...PER 12Z NAM CU RULE. WEAK SURFACE
FLOW/LACK OF MIXING DEPTHS EXPECTED TO HOLD MAXES IN THE LOW TO MID
70S...AS 850 MB TEMPS REMAIN AT OR BELOW 10 C.

EXTENDED...UPPER LEVEL RIDGING IN PLACE WILL SLIDE OFF TO THE EAST
FRIDAY BEFORE TROUGHING BUILDS IN FOR THE START OF THE WEEKEND.
FRIDAY IS EXPECTED TO REMAIN DRY BEFORE A SHORTWAVE APPROACHES THE
CWA ON SATURDAY BRINGING THE NEXT CHANCE FOR PRECIPITATION.  BROAD
UPPER LEVEL RIDING THEN BUILDS IN OVER THE CENTRAL AND EASTERN CONUS
NEXT WEEK.  TEMPERATURES WILL SLOWLY WARM BACK INTO THE 80S AS
SOUTHERLY FLOW TAKES OVER.

MARINE...

WESTERLY WINDS BECOMING NORTHWEST AND HOLDING MOSTLY IN THE 15 TO 25
KNOT RANGE THROUGH TONIGHT. SURFACE HIGH PRESSURE WILL
GRADUALLY BUILD IN FROM THE WEST WEDNESDAY INTO THURSDAY...ALLOWING
WINDS TO BECOME LIGHT FOR WEDNESDAY NIGHT AND THURSDAY.

COLD AIR REMAINING OVER OVER THE WARMER LAKE WATERS WILL CREATE
UNSTABLE CONDITIONS AND CONTINUE TO PROVIDE A LOW CHANCE OF
WATERSPOUTS THROUGH EARLY THURSDAY MORNING.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
&&

$$

AVIATION.....JVC
SHORT TERM...DRC
LONG TERM....SF/SS
MARINE.......SF


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


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