FXUS63 KDTX 011730
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1230 PM EST TUE DEC 1 2009
.AVIATION...
MVFR STRATUS WILL CONTINUE TO LIFT NORTHWARD WHILE ERODING THIS
AFTERNOON DUE TO THE DRY SOUTHWESTERLY FLOW. DEEP COLUMN RIDGING
WILL BRIEFLY SWEEP THROUGH SOUTHEASTERN MICHIGAN TONIGHT IN
ADVANCE OF THE NEXT LOW PRESSURE SYSTEM. THEREFORE...SOME
TRANSIENT HIGH CLOUDS MAY PASS OVERHEAD TONIGHT...BUT SKY FRACTION
WILL LARGELY BE NIL. VERY SHALLOW GROUND FOG IS POSSIBLE TOWARDS
DAYBREAK TOMORROW BUT CONFIDENCE IN THIS IS EXTREMELY LOW. HIGH
CLOUDS WILL INFILTRATE THE REGION BEGINNING TOMORROW DURING THE
DAY...BUT ONLY SLOWLY LOWER. AT THIS TIME...RAIN IS EXPECTED TO
HOLD OFF UNTIL VERY LATE TOMORROW AFTERNOON/TOMORROW EVENING.
&&
.PREV DISCUSSION...ISSUED 329 AM EST TUE DEC 1 2009
SHORT TERM...TODAY
LATEST UPPER AIR AND WATER VAPOR ANALYSIS SHOWING THE CLIPPER
SYSTEM RAPIDLY LIFTING ACROSS NORTHERN LAKE HURON EARLY THIS
MORNING. NARROW RIBBON OF MODEST ISENTROPIC ASCENT ACCOMPANYING
THIS SYSTEM NOW EXITING THE REGION. MOISTURE AND FORCING PROVED
TOO LIMITED THIS FAR SOUTH TO GENERATE MUCH MORE THAN A FEW BRIEF
SNOW SHOWERS/FLURRIES/SPRINKLES. MOISTURE DEPTH LACKING NOW TO
EVEN SUSTAIN A STRATUS DECK ACROSS SOUTHERN AREAS WITHIN A
PREDOMINANT SOUTHWEST LOW LEVEL FLOW.
WEAK SURFACE RIDGING WILL TAKE CONTROL TODAY AS THE UPPER LEVEL
FLOW BRIEFLY BECOMES ZONAL. RESIDUAL LOW LEVEL THERMAL GRADIENT
WILL REMAIN IN THE WAKE OF A SFC TROUGH PASSAGE THIS MORNING. THIS
'WARM' FRONTAL FEATURE WILL SHIFT NORTHEAST AS THE SOUTHWEST FLOW
REDEVELOPS INTO THE AFTERNOON. MODEST RESPONSE NOTED IN THE LATEST
MODEL THERMAL FIELDS...WITH MIXING SUFFICIENT ENOUGH TO TAP INTO THE
+2-3C WARMING AT 925MB. THIS WILL TRANSLATE INTO HIGHS RANGING FROM
LOWER 40S FAR NORTH TO UPPER 40S NEAR THE OHIO BORDER. WEAK ASCENT
OVER THE FRONTAL ZONE MAY PROMOTE POCKETS OF STRATUS...AIDED BY
BETTER MORNING INSOLATION.
LONG TERM...
LATEST WATER VAPOR IMAGERY SHOWS A GOOD SOUTHWARD PUSH OVER
WESTERN CANADA...WITH THE GOOD HEIGHT FALLS OCCURRING OF THE
NORTHERN ROCKIES...THIS SHOULD ALL BUT SEAL THE DEAL FOR WEDNESDAY
NIGHTS SYSTEM...AS CUTOFF LOW/STORM SYSTEM PUSHING INTO TEXAS
TRACKS WEST OF THE APPALACHIANS. ALTHOUGH...THE 00Z GFS IS STILL
INDICATING A COLDER TRACK THROUGH PITTSBURGH PA. WITH CONVECTION
OVER THE WESTERN GULF COAST STATES BEING A KEY COMPONENT...AM
LEARY OF THE GFS SOLUTION (AS LOCAL WRF-HEMI GIVES CREDENCE TO
THIS)...AND HAVE A PREFERENCE TO THE STRONGER AND FARTHER WEST
TRACK THROUGH NORTH CENTRAL/NORTHEAST OHIO...A BLEND OF THE 00Z
UKMET/NAM. EVEN THOUGH THIS TRACK IS STILL EAST OF THE AREA...IT
LOOKS LIKE WE WILL BE DEALING WITH A MOSTLY RAIN EVENT OR WET SNOW
WHICH STRUGGLES TO ACCUMULATE. WITH THE WARM ORIGINS OF THE
SOUTHERN SYSTEM...LACK OF INITIAL COLD AIR TO START OUT WITH
(MAXES IN THE MID TO UPPER 40S WEDNESDAY)...AND WARM GROUND
(FOLLOWING TOP 10 WARMEST NOVEMBERS ON RECORD)...CHANGEOVER TO
SNOW LOOKS TO BE OCCURRING A BIT TOO LATE TO EXPECT ANY
SIGNIFICANT SNOWFALL (ESPECIALLY ON THE ROADS). IN FACT...THE 00Z
NAM HOLDS SFC-925 MB TEMPS ABOVE FREEZING THROUGH THE ENTIRE
NIGHT. EVEN WITH THE COLDER AND FARTHER EAST SOLUTION OF THE
GFS...SURFACE WET BULB TEMPERATURES FAIL TO DROP TO 32 DEGREES
EVERYWHERE. THINKING THE EAST HALF OF THE CWA WILL BE HARD PRESSED
TO SEE MUCH ACCUMULATION...WITH THE WEST HALF (TRI-CITIES) OF THE
CWA SEEING ABOUT 2 INCHES OF WET SNOW.
STRONG SUBSIDENCE/MID LEVEL DRY SLOT PUNCHING INTO SOUTHEAST
MICHIGAN RIGHT AROUND OR JUST AFTER 12Z THURSDAY WILL QUICKLY END
PRECIPITATION (AT LEAST FOR A PERIOD) BEFORE LAKE MICHIGAN ACTIVITY
GETS GOING WITH 850 MB TEMPS FALLING TO -14 C THURSDAY NIGHT.
THERE WILL BE OPPORTUNITIES FOR LAKE ENHANCED SNOW SHOWERS FRIDAY
AND SATURDAY AS CYCLONIC FLOW/UPPER LEVEL TROUGH AXIS PERSISTS OVER
THE GREAT LAKES REGION...WITH SEVERAL EMBEDDED SHORTWAVES. THE FLOW
IS THEN FORECASTED TO BECOME A BIT MORE ZONAL AS WE HEAD INTO
SUNDAY...ALLOWING A MODEST WARMUP...AS ENSEMBLE MEAN INDICATING 850
MB TEMPS RISING TO AROUND -10 C. IN ANY EVENT...PROBABLY LOOKING AT
MAXES IN THE 30S WITH MINS IN THE LOW/MID 20S THURSDAY AND
BEYOND...WITH POTENTIAL FOR MINS IN THE TEENS IF WE CLEAR OUT ANY
PARTICULAR NIGHT.
MARINE...
GUSTY SOUTHWEST WILL CONTINUE FOR SEVERAL MORE HOURS THIS MORNING
AS BETTER MIXING ACCOMPANIES THE PASSAGE OF A SURFACE TROUGH.
CURRENT ADVISORY/WARNING HEADLINES WILL REMAIN UNCHANGED...WITH
WINDS ACROSS THE LAKE HURON OPEN WATERS EXPECTED TO DROP BELOW
GALES AFTER 12Z.
A BRIEF PERIOD OF QUIET WEATHER WILL EVOLVE LATER TODAY INTO
WEDNESDAY WITH SURFACE RIDGING IN PLACE. THAT WILL BE SHORT
LIVED...HOWEVER...AS A STRONG LOW PRESSURE LIFTS FROM THE GULF COAST
THROUGH THE OHIO RIVER VALLEY WEDNESDAY NIGHT AND THURSDAY. EXACT
POSITIONING OF THIS STORM SYSTEM REMAINS IN QUESTION...BUT THE
POTENTIAL FOR GALE FORCE WINDS EXISTS LATE WEDNESDAY NIGHT AND ON
THURSDAY.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....CB
SHORT TERM...MR
LONG TERM....SF
MARINE.......MR
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