FXUS63 KDTX 251738
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1238 PM EST FRI DEC 25 2009
.AVIATION...
THE FIRST BAND OF RAIN IS ALMOST THROUGH THE TAF SITES...IT WILL
LINGER OVER MBS UNTIL ABOUT 19Z. BEHIND THIS LINE...SHOWERS WILL
FILL BACK IN THROUGH MUCH OF THE DAY BEFORE ENDING AROUND 03Z. IFR
CEILINGS NEAR 700FT WILL DOMINATE THIS EVENING WITH PERIODIC BREAKS
TO MVFR UNTIL LIFTING TONIGHT UP TO 2500FT. VISIBILITIES WILL REMAIN
AROUND 4-5SM UNTIL THE RAIN ENDS...THOUGH THEY MAY DROP BRIEFLY TO
3SM IN AREAS OF HEAVIER SHOWERS. EASTERLY WINDS GUSTING TO NEAR
25KTS WILL GRADUALLY DIMINISH THROUGH THE DAY AND THEN TURN
SOUTHERLY AROUND 06Z.
&&
.PREV DISCUSSION...ISSUED 1006 AM EST FRI DEC 25 2009
UPDATE...
TEMPERATURES CONTINUE TO WARM ACROSS SOUTHEAST MICHIGAN THIS
MORNING. WITH THE NEXT TIER OF COUNTIES ACROSS THE CENTRAL PORTION
OF THE CWA WARMING INTO THE MIDDLE 30S...ALLOWED THIS ROW TO
EXPIRE AT 10 AM. THE NEXT ROW NORTH...INCLUDING COUNTIES ALONG AND
NORTH OF INTERSTATE 69...IS SET TO EXPIRE AT NOON. SINCE
TEMPERATURES ARE STILL AROUND FREEZING AT A GOOD NUMBER OF
LOCATIONS WILL ALLOW THE ADVISORY TO RUN ITS COURSE WITH AN
EXPECTED EXPIRATION AT NOON WHEN TEMPERATURES SHOULD REACH THE
MIDDLE 30S. NO ADDITIONAL UPDATES TO THE FORECAST WITH THIS ISSUANCE.
PREV DISCUSSION...ISSUED 301 AM EST FRI DEC 25 2009
SHORT TERM...TODAY
LARGE SURGE OF MOISTURE WILL SPREAD INTO THE AREA ALONG/IN ADVANCE
OF A WARM FRONT WHICH IS LIFTING STEADILY NORTH AS VERY STRONG LOW
SPINS UP OVER THE MID MISSOURI VALLEY. MOST LOCATIONS FROM THE CITY
OF DETROIT SOUTH TO THE OHIO BORDER HAVE ALREADY CLIMBED ABOVE THE
FREEZING MARK...SO PRECIPITATION WILL START AS RAIN...AND DO NOT
EXPECT ANY ICING. WITH THIS IN MIND...WITH REMOVE WASHTENAW COUNTY
FROM THE WINTER WEATHER ADVISORY. FROM THE NORTHERN SUBURBS INTO THE
THUMB AND SAGINAW VALLEY...TEMPERATURES WILL BE IN THE UPPER 20S TO
LOWER 30S AT THE ONSET OF PRECIPITATION...SO A SEVERAL HOUR WINDOW
OF MINOR ICING IS POSSIBLE BEFORE TEMPERATURES CLIMB TOWARDS 35 BY
MIDDAY AND ON TO NEAR 40 DURING THE AFTERNOON. WILL LEAVE THE WINTER
WEATHER ADVISORY IN PLACE FOR THIS POTENTIAL DURING THE MORNING.
LONG TERM...
TODAY LOOKS TO BE THE WARMEST DAY OF THE WEEK...WITH TEMPERATURES
THEN FALLING THROUGH EARLY NEXT WEEK.
THE EXPANSIVE STORM SYSTEM CENTERED OVER THE MIDWEST (IOWA) WILL
BEGIN TO FILL...AS IT WOBBLES OFF TO THE NORTHEAST. THE
CIRCULATION/COLD POOL WILL NOT MOVE THROUGH THE CENTRAL GREAT LAKES
UNTIL LATE IN THE WEEKEND. THIS SYSTEM WILL BE BOOTED OUT OF THE
AREA AS A STRONG UPPER WAVE/TROUGH DROPS SOUTHEAST THROUGH THE
EASTERN GREAT LAKES MONDAY NIGHT.
OCCLUSION WILL WORK NORTH OF THE CWA AROUND OR JUST
AFTER MIDNIGHT (THUS RAIN DURING THE EVENING POSSIBLY CHANGING TO
SNOW)...WITH IMPRESSIVE 700 MB DRY SLOT (RH 20 PERCENT) MOVING
IN OVERNIGHT...LIKELY ENDING OUR PRECIPITATION CHANCES TEMPORALLY.
LOW LEVEL COLD ADVECTION IS ALSO IMPRESSIVE LATE TONIGHT AS 850 MB
TEMPS PLUMMET INTO THE NEGATIVE LOWER TEENS SATURDAY MORNING. WITH
THE FLOW REMAINING SOUTH-SOUTHWEST DURING SATURDAY...LAKE MICHIGAN
WILL NOT BE MUCH OF A CONTRIBUTOR. NONE-THE-LESS...ALL MODELS
SHOWING INCREASING 850-700 MB RH (IN EXCESS OFF 75 PERCENT) BY
DAYS END WITH STEEP LOW LEVEL LAPSE RATES...AND THINKING WE SHOULD
AT LEAST SEE SCATTERED SNOW SHOWERS...CONCENTRATED THE MOST THE
FARTHER WEST ONE TRAVELS.
BETTER CHANCE FOR SNOW SHOWERS AS 500 MB LOW OVER THE WESTERN GREAT
LAKES IS FORECASTED TO SWING INTO SOUTHERN LOWER MICHIGAN DURING
SUNDAY....PER 00Z UKMET/GFS/CANADIAN GLOBAL. PLANNING ON CARRYING
SCATTERED 50 POPS SATURDAY NIGHT-SUNDAY.
IT LOOKS TO BE A REAL CLOSE CALL EARLY NEXT WEEK...BUT APPEARS THE
ARCTIC EXPRESS WILL ONLY PROVIDE A GLANCING BLOW (SHORT LIVED) AS
UPPER LEVEL RIDGE BUILDS OVER THE WESTERN GREAT LAKES ON TUESDAY
(PER 00Z EUROPEAN). EVEN SO...EXPECTING MAXES TO HOLD IN THE 20S ON
TUESDAY BASED ON FORECASTED 925 MB TEMPS AROUND -10 C...AS MINS
CLIMB OUT OF THE TEENS MONDAY NIGHT (SINGLE NUMBERS IF WINDS
DECOUPLE).
MARINE...
STRONG EASTERLY WINDS WILL DEVELOP ACROSS THE CENTRAL GREAT LAKES AS
A STRONG LOW PRESSURE SYSTEM TRACKS NORTHWARD THROUGH THE CENTRAL
PLAINS THROUGH TODAY. GALE FORCE WIND GUSTS ARE EXPECTED ACROSS THE
NORTHERN HALF OF LAKE HURON...WITH GUSTS TO 30 KNOTS EXPECTED ACROSS
THE REMAINDER OF THE LAKE. WINDS ARE EXPECTED TO DECREASE OVERNIGHT
FRIDAY NIGHT AS THE LOW PRESSURE SYSTEM STALLS AND BEGINS TO WEAKEN.
IN ADDITION TO THE WINDS...PRECIPITATION WILL OCCUR ACROSS THE
CENTRAL GREAT LAKES AS THIS SYSTEM LIFTS TO OUR WEST. A WINTRY MIX
OF FREEZING RAIN AND SLEET WILL OCCUR EARLY THIS MORNING BEFORE
CHANGING OVER TO ALL RAIN BY AFTERNOON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
GALE WARNING...LHZ361-LHZ362...UNTIL 4 AM SATURDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON INCLUDING OUTER SAGINAW BAY...UNTIL 4 AM SATURDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....DRK
UPDATE.......KURIMSKI
SHORT TERM...DG
LONG TERM....SF
MARINE.......DG
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
