Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 051028
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
628 AM EDT WED AUG 5 2015

.AVIATION...

HIGH PRESSURE WILL SUPPORT FAVORABLE AVIATION CONDITIONS THROUGH THE
TAF PERIOD. MOSTLY CLEAR SKIES AND LIGHT WINDS ARE EXPECTED...WITH
JUST SOME PASSING 6000-8000 FOOT CLOUDS. THERE IS ALSO A LOW CHANCE
OF SHALLOW RADIATION FOG LATE TONIGHT.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

.PREV DISCUSSION...ISSUED 358 AM EDT WED AUG 5 2015

SHORT TERM...TODAY AND TONIGHT

UPPER LEVEL NEGATIVE PV ADVECTION TODAY WITH UPPER LEVEL RIDGE AXIS
CRESTING OVER THE CENTRAL GREAT LAKES TONIGHT. THUS...LITTLE RISK
OF SHOWERS TODAY AS MID LEVEL DRY AIR IS ALSO BETTER ESTABLISHED
AS WELL. 850 MB TEMPS JUST SLIGHTLY COOLER TODAY COMPARED TO
YESTERDAY...RESULTING IN HIGHS IN THE UPPER 70S TO AROUND 80
DEGREES UNDER MOSTLY SUNNY SKIES. ANOTHER FAVORABLE RADIATING
NIGHT WITH MINS FALLING INTO THE 50S.

LONG TERM...

THE INFLUENCE OF SURFACE HIGH PRESSURE WILL CONTINUE OVER
SOUTHEASTERN MICHIGAN THURSDAY AND THURSDAY NIGHT. ENTRANCE REGION
OF A COHERENT UPPER LEVEL JET MAXIMUM WILL PUSH EASTWARD PLACING
UPPER LEVEL CONFLUENCE DIRECTLY OVER LOWER MICHIGAN. AN INCREMENTAL
INCREASE IN LOWER TROPOSPHERIC MOISTURE MAY LEAD TO AN UPTICK IN SKY
FRACTION...HOWEVER SREF HAS ITS DOUBT ON QUALITY OF BOUNDARY LAYER
MOISTURE. DAMPENING MIDLEVEL RIDGE AND ASSOCIATED ANTICYCLONIC
VORTICITY MINIMUM WILL BE FLUSHED THROUGH THE REGION THURSDAY NIGHT
AND EARLY FRIDAY.

THE FORECAST FOR PRECIPITATION BECOMES MUDDLED AND UNCERTAIN FOR
FRIDAY AFTERNOON IN ADVANCE OF AN APPROACHING SHORTWAVE AND LOW
PRESSURE SYSTEM. ORIGINS OF THE SHORTWAVE IN QUESTION ARE FROM THE
ENERGY NOW OVER NORTHERN CALIFORNIA. IT APPEARS THE PRECIPITATION
FORECAST HINGES ON THE AMOUNT OF PRE-EXISTING CONVECTION/RAIN THAT
WILL PUSH INTO THE CWA FROM UPSTREAM OVER MN AND WI. ECMWF IS
BULLISH IN A RELATIVE SENSE COMPARED TO THE NCEP SOLUTIONS. AT THE
SYNOPTIC SCALE SOUTHEASTERN MICHIGAN WILL RESIDE IN A ZONE OF
FAVORABLE MIDLEVEL DEFORMATION WHICH AT THIS TIME SUPPORTS AN ENTRY
LEVEL LOW CHANCE POP FOR THE AREA.

A REESTABLISHMENT OF THE WESTERLY JET AXIS OVERHEAD INCREASES TIMING
UNCERTAINTIES WITH REGARDS TO INDIVIDUAL SHORTWAVE ELEMENTS FOR THE
WEEKEND.

MARINE...

NORTHWESTERLY WINDS OF 10 TO 20 KNOTS THAT ARE IN PLACE OVER THE
CENTRAL GREAT LAKES WILL SLOWLY DECREASE TODAY AS SURFACE HIGH
PRESSURE BUILDS INTO THE REGION. THE SURFACE WIND FIELD WILL THEN
BECOME VARIABLE FOR THURSDAY AND EARLY FRIDAY AS THE CENTER OF THE
SURFACE HIGH BECOMES ANCHORED OVER PORTIONS OF SOUTHERN LAKE HURON.
ATTM...THE CURRENT FORECAST SUPPORTS AN EASTERLY FLOW TRAJECTORY
DEVELOPING FOR A GREATER PORTION OF THE AREA ON THURSDAY.

&&

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

$$

AVIATION.....SF
SHORT TERM...SF
LONG TERM....CB
MARINE.......CB


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



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