Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 042255
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
655 PM EDT FRI SEP 4 2015

.AVIATION...

PREDOMINATELY VFR CEILINGS EXPECTED TO PERSIST TONIGHT AND SATURDAY
AS MOISTURE CONTENT SLOWLY DECREASES WITHIN THE LINGERING LOW
PRESSURE SWIRL OVER LOWER MICHIGAN. LIGHT FOG /MAINLY MVFR -
POSSIBLE IFR AT THE FAVORED TERMINALS LIKE YIP.PTK.MBS/ IS EXPECTED
ONCE AGAIN TOWARD DAYBREAK. OTHERWISE...DIURNAL DEVELOPMENT OF
CUMULUS IS AGAIN ANTICIPATED WITH ONLY A LOW CHANCE FOR A SHOWER OR
STORM AT THE TERMINALS. WINDS WILL REMAIN LIGHT THROUGH THE PERIOD.

FOR DTW...CEILINGS BELOW 5KFT ARE POSSIBLE OVERNIGHT...AS ANOTHER
SPOKE OF ENHANCED CLOUDS SLINGS THROUGH FROM THE WEST. THE PRESENCE
OF CLOUDS SHOULD HELP KEEP FOG FORMATION IN CHECK...EXPECTING
REDUCTIONS TO REMAIN MVFR.

//DTW THRESHOLD PROBABILITIES...

* MEDIUM FOR CIG AT OR BELOW 5000 FEET TONIGHT.

* LOW FOR THUNDERSTORMS SATURDAY.

&&

.PREV DISCUSSION...ISSUED 343 PM EDT FRI SEP 4 2015

SHORT TERM...TODAY AND TONIGHT

WITH LOW PRESSURE PIVOTING TO THE NORTH NORTHWEST AND SLOWLY AWAY
FROM THE AREA...EXPECT THE THICK CLOUD COVER OVER MOST OF THE
NORTHERN 2/3 OF THE FORECAST AREA TO BREAK UP TO SOME DEGREE THROUGH
THE MID AFTERNOON AND EVENING. SCATTERED SHOWER ACTIVITY ALSO
LARGELY DISSIPATE EARLY THIS EVENING WITH THE LOSS OF DAYTIME
HEATING EARLY. WITH LOW LEVEL TROUGH AXIS STILL DRAPED BACK SOUTH
OVER LOWER MICHIGAN TONIGHT FROM THIS LOW...WEAK FLOW AND PARTLY
CLOUDY SKIES MAY LEAD TO SOME FOG DEVELOPMENT LATE TONIGHT AS
RESIDUAL LOW LEVEL MOISTURE REMAINS IN PLACE FROM HEAVY RAINS ON
THURSDAY. THIS AXIS WILL ALSO MAINTAIN AT LEAST AN ISOLATED CHANCE
OF SHOWERS ON THROUGH THE OVERNIGHT. MEANWHILE...TEMPERATURES WILL
REMAIN ABOVE AVERAGE WITH THIS HIGHER MOISTURE CONTENT...WITH
MINIMUM TEMPERATURES OVERNIGHT TONIGHT FALLING INTO THE MIDDLE 60S
MOST LOCATIONS...OR ABOUT 5 DEGREES ABOVE AVERAGE.

LONG TERM...

THE LETHARGIC LOWER LEVEL PV ANOMALY SPINNING OVER SOUTHERN LOWER
MICHIGAN WILL REMAIN OVERHEAD ON SATURDAY. A LOSS OF THE CYCLONIC
TRAJECTORY IN THE FORECASTED MIDLEVEL WIND FIELD SUGGESTS THE
FEATURE WILL BE ON ITS LAST LEGS. STILL SOME QUESTION ON LOW LEVEL
STRATUS...BUT OWING TO ITS SHELF LIFE...A GREATER ENTRAINMENT OF DRY
AIR IS EXPECTED INTO THE SYSTEM. THIS WILL LEAD TO AREAS OF SUNSHINE
OVER THE FORECAST AREA WHICH WITH WEAKLY CAPPED INSTABILITY A CHANCE
OF SHOWERS AND THUNDERSTORMS IS REQUIRED. OUT OF RESPECT FOR THE
RIDGE...KEPT WITH A WARM FORECAST WITH TEMPERATURES REACHING THE
MIDDLE TO UPPER 80S. HEAT INDICES ARE FORECASTED TO REACH 90 DEGREES
ACROSS THE SOUTEHRN CWA.

WEAK AND DIFFUSE CYCLONIC VORTICITY RIBBON OVER THE CWA WILL BE
SHEARED EASTWARD OUT OF THE STATE ON SUNDAY. LOCALIZED AVA SET FOR
THE DAYLIGHT HOURS ON SUNDAY WILL BOLSTER THE RIDGE LOCALLY UNDER
INCREASED DEEP COLUMN SUBSIDENCE. CONDITIONS ARE EXPECTED TO BECOME
DOWNRIGHT COMFORTABLE WITH TEMPERATUERS PUSHING 10 TO 12 DEGREES
ABOVE EARLY SEPTEMBER AVERAGES. HEAT INDICES SUNDAY WILL INCREMENT
UPWARD INTO THE LOWER TO MIDDLE 90S.

A TRANSITION FROM UPPER RIDGING AND A TROPICAL AIRMASS WILL
TRANSITION TO GRADUALLY LOWERING UPPER HEIGHTS AND TEMPERATURES FROM
LABOR DAY INTO THE NEXT WORK WEEK. UNSETTLED WEATHER WILL ACCOMPANY
THIS PROCESS WITH RAIN CHANCES IN THE FORECAST FROM MONDAY NIGHT
INTO AT LEAST MIDWEEK. LABOR DAY ITSELF APPEARS TO BE ONE MORE
HOT...HUMID...AND MAINLY DRY DAY AS UPPER RIDGING LOOKS TO HOLD AND
WARM MID-LEVEL TEMPS SHOULD LIMIT INSTABILITY.

MARINE...

SURFACE AND UPPER LEVEL HIGH PRESSURE WILL LEAD TO PREDOMINATLY
QUIET HOLIDAY WEEKEND MARINE WEATHER OVER THE REGION. STILL LOOKING
AT A LOW CHANCE FOR A SHOWER OR THUNDERSTORM DURING THE DAY ON
SATURDAY...ALTHOUGH THE GREATEST POTENTIAL APPEARS TO BE FOR THE
INLAND AREAS. LIGHT SOUTHERLY WINDS WILL BE COMMONPLACE...BEFORE
SOUTHWEST WINDS EVENTUALLY INCREASE INTO THE 10 TO 20 KNOT RANGE
AHEAD OF AN APPROACHING FRONTAL BOUNDARY SUNDAY NIGHT AND MONDAY.

&&

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

$$

AVIATION.....MANN
SHORT TERM...DG
LONG TERM....CB/DT
MARINE.......CB


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


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