Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 250453
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1153 PM EST MON NOV 24 2014


.AVIATION...

//DISCUSSION...

EXTENSIVE MVFR STRATUS WILL HOLD FIRM TONIGHT AS COLD AIR CONTINUES
TO FILTER INTO SOUTHEAST MICHIGAN. GUSTY SOUTHWEST WINDS OF 25 TO
35 KNOTS WILL SLOWLY EASE WITH TIME DURING THE OVERNIGHT HOURS.
CEILINGS ARE EXPECTED TO EVENTUALLY LIFT TO VFR TUESDAY AFTERNOON AS
HIGH PRESSURE BUILDS IN ACROSS THE OHIO VALLEY.

FOR DTW...SOUTHWEST WINDS /230-250 DEGREES/ OF 30 TO 35 KNOTS
WILL CONTINUE TO SLOWLY DIMINISH DURING THE OVERNIGHT HOURS.

//DTW THRESHOLD THREATS...

* HIGH CONFIDENCE IN CEILING BELOW 5000 FEET TONIGHT THROUGH
  TUESDAY.

* HIGH CONFIDENCE IN STRONG CROSSWINDS FROM THE SOUTHWEST /230 TO
  250 DEGREES/ THROUGH EARLY TUESDAY MORNING.

&&

.PREV DISCUSSION...ISSUED 354 PM EST MON NOV 24 2014

SHORT TERM... THROUGH TONIGHT

WIND EVENT CONTINUES OVER SE MI THIS AFTERNOON. INITIAL WIND SURGE
ON THE COLD FRONT MOVED THROUGH THE DETROIT METRO/OHIO BORDER REGION
EARLIER THIS AFTERNOON WITH A QUICK POP OF 50 KT GUSTS TIED TO STEEP
INITIAL ISENTROPIC POST-FRONTAL DOWNGLIDE. BUBBLE OF SURFACE
PRESSURE FALLS OF 7-8 MB/3HR WORKING THROUGH THE REGION AT THIS
HOUR ALONG WITH CONTINUED AGRESSIVE LOW-LEVEL COLD AIR ADVECTION
MAINTAINING STEEP LAPSE RATES WILL CAUSE GUSTS OF 40-50 KT TO
CONTINUE INTO LATE AFTERNOON/EARLY EVENING. FEEL THAT 50 KT
GUSTS...WHILE STILL VERY POSSIBLE...WILL BE THE EXCEPTION FOR THE
REMAINDER OF THE PERIOD SO NO CHANGES TO ADVISORY/WARNING ARE
PLANNED AT THIS POINT...THOUGH WILL CONTINUE TO MONITOR TRENDS.
WINDS WILL DIMINISH SLOWLY DURING THE OVERNIGHT PERIOD AS STEEP LOW-
LEVEL LAPSE RATES ARE MAINTAINED...WITH 30 KT GUSTS STILL POSSIBLE
THROUGH AROUND MIDNIGHT.

TROWAL AREA/DEFORMATION AXIS CURRENTLY RESPONSIBLE FOR WIDESPREAD
PRECIPITATION OVER NORTHWEST HALF OF OUR CWA. THIS WILL CONTINUE TO
LIFT SLOWLY NORTH WHILE COLDER AIR CONTINUES TO FILTER IN FROM THE
WEST AND SOUTHWEST. THE COLDER AIR WILL CAUSE A RATHER QUICK
CHANGEOVER TO SNOW FROM ABOUT 00Z-03Z FROM WEST TO EAST OVER THE
CWA. BY THAT TIME THE PRECIP SHIELD WILL BE LOCATED OVER THE SAGINAW
VALLEY AND CONTINUING TO LIFT NORTH. IT IS A CLOSE CALL FOR
ACCUMULATING SNOW...BUT 12Z MODEL SUITE IS IN AGREEMENT THAT MOST OF
THE PRECIPITATION SHOULD BE TO THE NORTH OF OUR CWA BY THE TIME
CHANGEOVER HAPPENS. WHAT SNOW DOES FALL WILL LIKELY TAKE A
FEW HOURS TO ACCUMULATE GIVEN RELATIVELY WARM GROUND AND
SURFACE TEMPS. CURRENT GRIDS REFLECT THIS WITH JUST AROUND A
HALF INCH TO AN INCH EXPECTED OVER MIDLAND AND BAY COUNTIES.
SOUTHEAST HALF OF THE CWA SHOULD REMAIN MOSTLY DRY OVERNIGHT...BUT
GRADUAL VEERING OF THE LOW/MIDLEVEL WINDS WITH TIME SHOULD ALLOW
SOME LIGHT LAKE-ENHANCED SHOWERS TO EXPAND BACK SOUTHWARD TOWARD THE
I-69 CORRIDOR BY LATE TONIGHT. TEMPERATURES WILL CONTINUE TO
PLUMMET FROM THEIR HIGHS IN THE 50S TO NEAR 60 EARLIER TODAY...ON
THEIR WAY TO LOWS AROUND 30 BY 12Z TUESDAY.

LONG TERM...TUESDAY THROUGH SUNDAY

A NORTHERN STREAM SHORTWAVE TROUGH WILL DROP INTO THE NORTHERN GREAT
LAKES TUESDAY HELPING TO STALL THE EXIT OF THE SFC TROUGH LAID OUT
BY MONDAYS STRONG LOW PRESSURE SYSTEM. COLD AIR WILL BE FILL IN
QUICKLY BEHIND THE DEPARTING LOW WITH A THERMAL TROUGH AROUND -11C
AT 850MB AND -6C AT 925MB BY 12Z TUESDAY. MOISTURE WILL STILL BE
LINGERING OVER CENTRAL MI FROM THE DEPARTING LOW...WITH MODEL
SOUNDINGS SHOWING MOISTURE THROUGHOUT THE COLUMN UP TO 700MB. IN
ADDITION...THE THERMAL PROFILE MAY BE ENOUGH TO KICK UP A FEW LAKE
ENHANCED SNOW SHOWERS OFF LAKE MI...BUT SHOULD STRUGGLE TO REACH SE
MI AS THE FORCING IS ON THE WEAK SIDE. WITH THE ADDITIONAL BROAD
LIFT FROM THE SHORTWAVE TROUGH...AND A THERMAL PROFILE WORTHY OF AT
LEAST A MENTION OF LAKE EFFECT GENERATION OFF LAKE MI...WILL
CONTINUE WITH LIKELY POPS ACROSS THE SAGINAW VALLEY...TAPERING OFF
TO THE SOUTH. HIGHEST CHANCE OF SHOWERS WILL BE IN THE
MORNING...DECREASING THROUGH THE DAY AS THE FORCING AND MOISTURE
THIN OUT AS HIGH PRESSURE BUILDS INTO THE AREA.

WEDNESDAY SHOULD END UP BEING A FAIRLY QUIET DAY WITH THE
AFOREMENTIONED HIGH SLIDING OVERHEAD. THE BROAD VIEW SHOWS SEVERAL
FEATURES THAT WE MAY DODGE WITH A POTENTIAL NOR`EASTER TRACKING ON
THE ATLANTIC COAST...A WEAK CLIPPER TRACKING SOUTH THROUGH THE OHIO
VALLEY...AND RESIDUAL TROUGHING TO OUR NORTH. THIS HIGH WILL DRY OUT
THE COLUMN ABOVE 900MB...BRING LIGHT WINDS...AND TRY TO ERODE THE
LOW LEVEL CLOUD DECK. UNFORTUNATELY...THE PEAKS OF SUN WILL DO
LITTLE TO THE THERMAL FIELD RESULTING IN HIGH TEMPS IN THE LOW/MID
30S.

THANKSGIVING WILL START WITH H85 TEMPS IN THE -10 TO -15C RANGE AS A
500 MB TROUGH AXIS SWINGS THROUGH. A LOBE OF POTENTIAL VORTICITY
COINCIDENT WITH PEAK DIURNAL EFFECTS WILL HELP KICK UP A LAKE EFFECT
SNOW RESPONSE. FLOW GENERALLY FROM THE NORTHWEST WILL KEEP ALL OF
SOUTHEAST MICHIGAN GAME FOR BANDING TO SETUP. HAVE A BROAD BRUSH
HALF INCH OF ACCUMULATIONS ACROSS THE AREA...BUT AS WE APPROACH
THURSDAY WILL BE ABLE TO PIN DOWN LOCATION OF LOW LEVEL CONVERGENCE
AND STEERING FLOW A BIT BETTER. AS OF NOW, BETTER ACCUMS SHOULD STAY
NW OF THE GLACIAL RIDGE. THE REMAINDER OF THE EXTENDED FORECAST WILL
BE WELL BELOW NORMAL FOR TEMPS /SAVE SATURDAY/ WITH LOW CONFIDENCE
ON ANY PARTICULAR SNOW CHANCE.

MARINE...

A STRONG LOW PRESSURE SYSTEM THAT PASSED THROUGH NORTHERN MICHIGAN
IS NOW ENTERING WESTERN QUEBEC. COMBINATION OF COLD AIR ENTERING THE
REGION AND A TIGHT PRESSURE GRADIENT IS RESULTING IN A WIDESPREAD
WIND EVENT ACROSS THE GREAT LAKES. MOST MARINE ZONES ARE
EXPERIENCING HIGH END GALE FORCE WINDS WITH THE EXCEPTION OF LAKE
ERIE WHICH HAS STORM FORCE. THIS PATTERN WILL CONTINUE THROUGH THE
OVERNIGHT...ESPECIALLY OVER CENTRAL LAKE HURON...AS TROUGHING WILL
LINGER EVEN AS THE LOW CONTINUES TO LIFT NORTHEAST. CURRENT
HEADLINES WILL REMAIN UNCHANGED AS THE EVENT IS UNDERWAY AND THE
FORECAST IS ON TARGET. LOW WATER ADVISORY ALSO REMAINS IN EFFECT FOR
LAKE ERIE AS SOUTHWEST FLOW WILL DROP WATER LEVELS SEVERAL FEET BELOW
DATUM. DESPITE THE SOUTHWEST GALES OVER SAGINAW BAY...THE FORECASTED
WATER LEVEL IS PROGGED TO REMAIN JUST ABOVE CHART DATUM...BOTTOMING
OUT LATE THIS EVENING. WINDS WILL DIMINISH RATHER QUICKLY OVERNIGHT
WITH ONLY OPEN WATERS OF LAKE HURON STILL HOLDING ON TO GALES. HIGH
PRESSURE WILL START TO BUILD INTO THE REGION TUESDAY FROM THE SOUTH
WHICH WILL RESULT IN DECREASING WINDS THROUGH MID WEEK.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...GALE WARNING UNTIL 4 PM EST TUESDAY FOR LHZ462>464.

     GALE WARNING UNTIL 5 AM EST TUESDAY FOR LHZ362-421-422-441>443.

     GALE WARNING UNTIL 11 AM EST TUESDAY FOR LHZ363.

LAKE ST CLAIR...GALE WARNING UNTIL MIDNIGHT EST TONIGHT FOR LCZ460.

MICHIGAN WATERS OF LAKE ERIE...GALE WARNING UNTIL MIDNIGHT EST TONIGHT FOR LEZ444.

     LOW WATER ADVISORY UNTIL 4 PM EST TUESDAY FOR LEZ444.

&&

$$

AVIATION.....KURIMSKI
SHORT TERM...DT
LONG TERM....DRK/MM
MARINE.......DRK


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