Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 280400
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1200 AM EDT SUN SEP 28 2014

.AVIATION...

//DISCUSSION...

TIMING ON THICKENING HIGH CLOUDS CONTINUES TO FAVOR A POSITIVE
INFLUENCE ON FOG SUPPRESSION IN THE DTW CORRIDOR UP TO ABOUT PTK
WITH LESS CONFIDENCE AT FNT AND MBS. MOS GUIDANCE IS BULLISH ON
IFR/LIFR VISIBILITY RESTRICTION AT ALL TERMINALS AND INCOMING MODEL
SOUNDINGS SHOW SLIGHTLY BETTER SURFACE BASED MOISTURE PROFILES...
STILL DEEPER IN THE MBS AREA WHERE THE FORECAST WILL CALL FOR A
PERIOD OF LIFR FROM JUST BEFORE SUNRISE THROUGH MID MORNING. THE
BULK OF OBSERVATIONAL EVIDENCE THEN POINTS TO IFR IN THE FNT AREA
IMPROVING TO MVFR AT DTW. AS THE EVENTUAL FOG PATTERN DISSIPATES
DURING THE MORNING...BROAD SURFACE HIGH PRESSURE RANGING FROM THE
MIDWEST...OVER LOWER MICHIGAN...TO THE NEW ENGLAND COAST WILL
PROVIDE YET ANOTHER DAY OF FAVORABLE AVIATION CONDITIONS. VFR UNDER
LINGERING HIGH CLOUDS AND LIGHT WIND WILL LAST THROUGH THE DAY
FOLLOWED BY A DECREASING HIGH CLOUDS SUNDAY NIGHT.

//DTW THRESHOLD THREATS...

* NONE.

&&

.PREV DISCUSSION...ISSUED 344 PM EDT SAT SEP 27 2014

SHORT TERM...TONIGHT

THE PERPETUATION OF A HIGH AMPLITUDE PATTERN FEATURING UPPER RIDGING
EXPANDING TOWARD THE EAST COAST AND A CLOSED UPPER LOW OVER IOWA
WILL AGAIN YIELD A QUIET EVENING LOCALLY WITH MOSTLY CLEAR SKIES
UNDER PREDOMINANT LOW AND MID LEVEL RIDGING. ENVIRONMENT WILL
AGAIN BE FAVORABLE LATE TONIGHT FOR SOME FORM OF FOG DEVELOPMENT
GIVEN THE LIGHT WIND FIELD. PREVAILING BOUNDARY LAYER WINDS OVER
THE LAKES WILL BECOME MORE EASTERLY/SOUTHEASTERLY RELATIVE TO LAST
NIGHT...SO THERE MAY BE A BETTER MOISTURE FLUX COMPONENT OFF LAKE
ERIE. SOME NORTHWARD EXPANSION OF THE CIRRUS CANOPY NOTED OVER THE
OHIO VALLEY MAY HOWEVER PROVIDE A LIMITATION TO THE DEGREE OF
DEVELOPMENT...ENOUGH AT THIS STAGE TO SIMPLY RETAIN A PATCHY
MENTION. VERY GRADUAL MODERATION OF THE RESIDENT AIRMASS WILL
LEAVE LOWS ROUGHLY IN THE SAME RANGE AS THIS MORNING...READINGS
RANGING FROM MID 40S TO LOWER 50S.

LONG TERM...SUNDAY THROUGH FRIDAY

A FEW STRONG JETS SURGING INTO THE NW CONUS WILL BREAK DOWN THE
DOMINATE LONGWAVE RIDGE ACROSS THE COUNTRY THROUGH THE COURSE OF THE
WEEK. THIS PROGRESSIVE PATTERN WILL FLIP THE SCRIPT OVER THE GREAT
LAKES BY THE END OF THE WEEK WITH A DEEP TROUGH SETTLING IN. THOUGH
A PAIR OF HIGH PRESSURE SYSTEMS WILL CONTROL THE BETTER PART OF THE
FORECAST...THERE WILL BE TWO OPPORTUNITIES FOR PRECIPITATION WITH A
SHORTWAVE/COLD FRONT ON MONDAY NIGHT INTO TUESDAY AND THEN THE MORE
POTENT DEEP TROUGH AND COLD FRONT ON FRIDAY.

SUNDAY WILL REMAIN VERY PLEASANT ACROSS SE MI AS WEAKENING SFC HIGH
REMAINS IN PLACE AS A W/E ORIENTATED COLD FRONT SLOWLY DROPS OVER
LAKE SUPERIOR. LOOKING ALOFT...THE WEAK CUTOFF LOW MEANDERING OVER
THE CENTRAL PLAINS WILL PASS OVER THE REGION AS AN OPEN WAVE STAYING
HAVING LITTLE EFFECT AT THE SFC DUE TO THE RIDGE IN PLACE. WITH
HEIGHTS LOWERING SLIGHTLY EXPECT THE COLUMN TO RESPOND WITH
DECREASING TEMPS AS WELL ABOVE THE BL. MODELS SOUNDING SHOW THIS
COOLING GENERALLY ABOVE 800 MB BUT WITH MIXING HEIGHTS REMAINING
NEAR 900MB...THINK BL SHOULD RECOVER TO ONLY A DEGREE OR SO SHY OF
SATURDAYS MAX TEMPS IN THE MID 70S.

THE COLD FRONT TO THE NORTH WILL BEGIN DROPPING SOUTHWARD ON MONDAY
AS A SHORTWAVE DIVES THROUGH THE MIDWEST. THE PARENT LOW FOR THE
FRONT WILL BE WELL OFF TO THE EAST SO THE FRONT WILL NOT HAVE MUCH
POTENCY TO IT BUT MODELS ARE HINTING AT THE SHORTWAVE DEEPENING
OVER LOWER MI ADDING FAVORABLE HEIGHT FALLS TO THE MIX WHICH SHOULD
BE ENOUGH TO GENERATE SOME SHOWERS. THE ECMWF REMAINS THE STRONGEST
WITH THE WAVE...INTENSIFYING IT WHILE IT STALLS SLIGHTLY OVER
SOUTHERN MI. GFS KEEPS IT MORE SHEARED AND PROGRESSIVE WITH THE NAM
KIND OF IN THE MIDDLE GROUND DEVELOPING A STRONGER WAVE BUT SLIGHTLY
EAST OF THE AREA. WILL CONTINUE TO LEAN TOWARD THE ECMWF WHICH IS
GIVING GOOD RUN TO RUN CONSISTENCY.

HIGH PRESSURE OVER CANADA WILL THEN BUILD INTO THE AREA WITH THE
CENTER STAYING OFF TO THE NORTH PRESENTING US WILL COOLER EASTERLY
FLOW THROUGH THE MID WEEK. SHOULD BUILD BACK INTO THE LOW 70S BY
LATE IN THE WEEK AS FLOW BECOMES MORE SOUTHWESTERLY AHEAD OF THE
DEEPENING TROUGH. EXTENDED MODELS STACKING UP NICELY WITH THE TIMING
OF A COLD FRONTAL PASSAGE FRIDAY AFTERNOON WITH A SFC LOW TRACKING
UP FRONT. ITS A WAYS OUT BUT THIS WILL BE THE NEXT OPPORTUNITY FOR
RAIN.

MARINE...

HIGH PRESSURE WILL REMAIN IN CONTROL OF THE WEATHER OVER THE GREAT
LAKES THROUGH THE WEEKEND YIELDING FAVORABLE MARINE CONDITIONS. A
WEAKENING COLD FRONT WILL THEN DROP SOUTHWARD THROUGH THE REGION
MONDAY NIGHT WITH INCREASING NORTHEASTERLY WINDS BEHIND IT WHICH
WILL PERSIST INTO TUESDAY.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.

&&

$$

AVIATION.....BT
SHORT TERM...MR
LONG TERM....DRK
MARINE.......DRK


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