FXUS63 KDTX 101822
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
122 PM EST THU DEC 10 2009

.AVIATION...

STRONG WESTERLIES WILL CONTINUE THROUGHOUT THE PERIOD AS THE
TIGHT PRESSURE GRADIENT IS MAINTAINED BETWEEN THE LARGE LOW
PRESSURE SYSTEM NEAR THE CANADIAN MARITIMES AND THE SPRAWLING HIGH
CRAWLING ACROSS THE SOUTHERN CONUS. COLD CYCLONIC FLOW ACROSS THE
RELATIVELY WARM GREAT LAKES WILL KEEP SNOW SHOWERS A VIABLE
POSSIBILITY ACROSS THE AREA. GENERALLY...CONFIDENCE REMAINS LOW
IN TIMING ANY ORGANIZED ACTIVITY AND HAVE KEPT THE MENTION LARGELY
OUT OF TAFS. THE ONE EXCEPTION IS THE HIGHLY LOCALIZED AND PESKY SNOW
BAND DIRECTLY OVER KMBS. UPSTREAM KGRR RADAR IS SHOWING A
DISSIPATION OF THIS FEATURE OFF OF LAKE MICHIGAN...AND FEEL ANY
LIFR VISIBILITIES/CEILINGS WILL LIMITED TO THE NEXT COUPLE OF HOURS.
OTHERWISE...A VERY DRY AIRMASS WILL BLANKET THE STATE AND KEEP A
WIDESPREAD SCT TO BKN CEILING OF 030-040KFT.

&&

.PREV DISCUSSION...ISSUED 612 AM EST THU DEC 10 2009 

UPDATE...

LAKE EFFECT SNOW BANDS HAVE WEAKENED CONSIDERABLY IN INTENSITY 
ACROSS SOUTHEASTERN MICHIGAN. THE PREVIOUSLY SINGLE INTENSE BAND 
FROM HOWELL TO WHITE LAKE HAS BECOME MORE DIFFUSE WITH MUCH LOWER 
SNOWFALL RATES AND INTENSITY. IN ADDITION THE INLAND EXTENT OF 
FURTHER BANDS FROM LAKE MICHIGAN APPEARS LIMITED TO SOUTHWESTERN 
MICHIGAN AS THE CONVECTIVE DEPTH CONTINUES TO SHRINK DURING THE 
MORNING HOURS. GIVEN THE BULK OF THE SNOWFALL APPEARS TO BE OVER 
ACROSS THE ADVISORY AREA...WILL CANCEL THE WINTER WEATHER ADVISORIES 
ACROSS THE CWA.

SCATTERED SNOW SHOWERS ACROSS THESE AREAS WILL PRODUCE AN ADDITIONAL 
INCH OF ACCUMULATION TODAY AS LAKE EFFECT SNOW BANDS OCCASIONALLY 
MAKE IT FAR ENOUGH EASTWARD.

PREV DISCUSSION...ISSUED 611 AM EST THU DEC 10 2009 

SHORT TERM...TODAY

THE INTENSE LOW RESPONSIBLE FOR THE BLUSTERY WINTRY WEATHER 
YESTERDAY IS CURRENTLY OVER WESTERN QUEBEC AND WILL HEAD FOR THE 
CANADIAN MARITIMES TODAY. DESPITE THE DEPARTURE OF THE LOW...SNOW 
SHOWERS AND WINDY CONDITIONS WILL CONTINUE TO PLAGUE THE CENTRAL 
GREAT LAKES. A VERY TIGHT PRESSURE GRADIENT WILL BRING WINDY 
CONDITIONS TO THE CWA TODAY. HOWEVER 925 WINDS WILL BE MUCH LIGHTER 
TODAY...ONLY REACHING 35 TO 40 KNOTS. THEREFORE WIND GUSTS ARE ONLY 
EXPECTED TO TOP OUT AT 40 MPH AT TIMES TODAY AND STAY BELOW WIND 
ADVISORY CRITERIA WITH NO WIND HEADLINES ANTICIPATED.

CONTINUED COLD AIR ADVECTION WILL AGAIN MEAN HIGH TEMPERATURES TODAY 
SHOULD OCCUR DURING THE MORNING HOURS AS 850 MB TEMPERATURES PLUMMET 
TO THE UPPER TEENS BELOW ZERO...WITH -20 SNEAKING IN ACROSS THE 
EXTREME SOUTHERN CWA NEAR THE OHIO BORDER. OVERNIGHT TEMPERATURES 
HAVE STAYED A BIT HIGHER THAN EXPECTED...ESPECIALLY NORTH OF 
INTERSTATE 69 WITH THE ABUNDANT CLOUD COVER. THEREFORE WILL RAISE 
HIGHS TODAY A FEW DEGREES ACROSS THESE AREAS TO ACCOUNT FOR THE 
WARMER MORNING START AND LOWER TEMPERATURES AS THE DAY WEARS ON. THE 
COOLER AFTERNOON TEMPERATURES AND HIGH WINDS WILL BRING WIND CHILL 
VALUES TO AROUND ZERO DEGREES.

THE COLD 850 MB TEMPS WILL ALSO MEAN MORE FAVORABLE CONDITIONS FOR 
LAKE EFFECT SNOW AS DELTA T VALUES RISE FROM THE UPPER TEENS TO THE 
LOWER TO MIDDLE 20S. LAKE INDUCED CAPE VALUES WILL ALSO STAY 
FAVORABLE AT 700 TO 900 J/KG. HOWEVER THE CONVECTIVE DEPTH ACROSS 
LAKE MICHIGAN WILL SHRINK FROM 5K FT TO 3K FT BY THE AFTERNOON 
HOURS. THE MODELS ARE INDICATING THE CURRENT LAKE EFFECT SNOW BAND 
ACROSS THE INTERSTATE 96 CORRIDOR WILL SHIFT NORTHWARD AND DISSIPATE 
LATE THIS MORNING. WITH THE LESS FAVORABLE DEPTH AND TRANSIENT 
NATURE OF THE LES BANDS THE MODELS ARE SUGGESTING WILL LEAVE THE 
CURRENT WINTER WEATHER ADVISORY UP AS IS AND HOLD OFF ON ANY FURTHER 
HEADLINES...IF NEEDED...IF ADDITIONAL STATIONARY BANDS DEVELOP.

SNOWFALL AMOUNTS IN THE CURRENT ADVISORY LOOK DESCENT AS THE DTX 
OFFICE IS UNDER THE HEAVIEST BAND AND CRANKING OUT ABOUT AN INCH OF 
SNOW EVERY 2 HOURS WITH A STORM TOTAL CURRENTLY AT 3 INCHES. WILL 
TWEAK THE ADVISORY TO RAISE AMOUNTS AN INCH WITH 3 TO 5 INCHES OF 
STORM TOTAL EXPECTED...WITH THE HIGHEST AMOUNTS IN THE MOST 
PERSISTENT STATIONARY BAND LOCATED FROM HOWELL TO WHITE LAKE.

LONG TERM...TONIGHT THROUGH WEDNESDAY

LAKE EFFECT SNOW SHOWERS WILL CONTINUE TONIGHT AND INTO FRIDAY AS 
COLD AIR AND WESTERLY FLOW CONTINUE TO STREAM ACROSS LAKE MICHIGAN. 
MOST ACCUMULATIONS LOOK TO FALL BETWEEN I-94 AND I-69...AS MODEL 
LOW-LEVEL WIND FIELDS LOOK TO HAVE A SLIGHT SOUTH OF WEST COMPONENT. 
EXPECT INTENSITY TO CONTINUE TO DECREASE THROUGH THIS PERIOD AS 
MOISTURE DEPTH DECREASES...HOWEVER LAKE-850 TEMPERATURE 
DIFFERENTIALS WILL REMAIN QUITE HIGH AND THE SNOW GROWTH REGION WILL 
REMAIN SATURATED. ACCUMULATIONS ARE A BIT UNCERTAIN...BUT CURRENT 
FORECAST CALLS FOR JUST SLIGHTLY OVER AN INCH WITHIN THE LAKE EFFECT 
BAND TONIGHT AND UP TO ANOTHER HALF INCH FOR FRIDAY. WESTERLY WINDS 
WILL ALSO REMAIN GUSTY DURING THIS PERIOD...AS SOUTHEAST MICHIGAN IS 
PLACED WITHIN THE RETREATING AREA OF STRONG LOW PRESSURE OVER 
NORTHEAST CANADA AND A BUILDING SURFACE RIDGE OVER THE TENNESSEE 
VALLEY. THE GUSTY WINDS AND TEMPERATURES IN TEENS AND TWENTIES WILL 
ALLOW WIND CHILL VALUES TO REMAIN BETWEEN THE SINGLE DIGITS AND 
ABOUT 5 BELOW ZERO THROUGH TONIGHT THROUGH FRIDAY.

SURFACE RIDGE CENTERED TO OUR SOUTHEAST WILL EXTEND ACROSS LOWER 
MICHIGAN ON SATURDAY. THIS WILL BRING QUIETER WEATHER AS LAKE EFFECT 
IS CUT OFF BY A MORE SOUTHERLY WIND COMPONENT AND ALLOW FOR LIGHTER 
WINDS. MODELS SOLUTIONS CONTINUE TO STRUGGLE WITH HOW STRONG AN 
UPSTREAM WAVE PUSHING ACROSS CENTRAL CANADA WILL BE BY SATURDAY 
AFTERNOON...MAKING HIGH TEMPERATURES FOR SATURDAY A CHALLENGE. 
MODELS HAD PREVIOUSLY SHOWN WEAK SURFACE TROUGHING PUSHING INTO THE 
NORTHERN GREAT LAKES BY SATURDAY EVENING...BUT THIS SOLUTIONS IS NOW 
ONLY FAVORED BY THE GFS AND NAM. GEM/UK/EURO LIFT THIS SYSTEM NORTH 
BEFORE IT REACHES THE GREAT LAKES. WILL LEAN AWAY FROM THE WAVE 
PUSHING INTO THE LAKES AT THIS TIME...PREVENTING WARMER AIR FROM 
BEING PULLED UP INTO THE STATE...AND KEEP TEMPERATURES MORE IN LINE 
WITH PREVIOUS FORECAST THAN WITH 00Z MEX MOS.

NEXT LOW PRESSURE SYSTEM LOOKS TO IMPACT THE GREAT LAKES FOR THE 
BEGINNING OF NEXT WEEK. UPPER WAVE OR LOW OVER FAR NORTHWEST CANADA 
LOOKS TO PHASE WITH A WEAKER SHORTWAVE DIVING ACROSS 
CALIFORNIA...BUILDING A BROAD TROUGH OVER THE WEST. MEDIUM RANGE 
MODELS ARE IN LINE WITH EJECTING LEAD ENERGY OUT OF THIS TROUGH AND 
UP TOWARDS THE GREAT LAKES...WITH THE RESULTING SURFACE LOW 
CURRENTLY FORECAST TO PUSH ACROSS MICHIGAN ON MONDAY/MONDAY NIGHT. 
THIS SYSTEM LOOKS TO BE MUCH MUCH WEAKER THAN THE ONE WE DEALT WITH 
ON WEDNESDAY...BUT THE TRACK MAY PROVE SIMILAR. LATEST CONSENSUS 
FROM THE 00Z RUNS TAKES THE CENTER JUST NORTH OF A LINE FROM CHICAGO 
TO SAGINAW BAY...BUT THERE IS STILL A LOT OF ROOM BETWEEN NOW AND 
THEN TO SEE ADJUSTMENTS. GFS AND EURO AGREE THAT WARMER AIR WILL 
PRECEDE THE SYSTEM ON MONDAY...AND HAVE ADDED A RAIN/SNOW MENTION 
FROM THE I-69 CORRIDOR SOUTH AND BUMPED TEMPERATURES UP SEVERAL 
DEGREES. NOT WILLING TO GO AS HIGH AS MEX GUIDANCE WITH MAXES IN THE 
40S JUST YET THOUGH. GOOD MOISTURE AT THIS TIME LOOKS TO BE CONFINED 
TO THE LOWEST LEVELS (BELOW H800)...AND WILL NOT BE HIGHLIGHTING ANY 
BIG SNOW ACCUMULATIONS IN THE HAZARDOUS WEATHER OUTLOOK.

MARINE...

INTENSE LOW PRESSURE SYSTEM WILL MOVE EAST FROM WESTERN QUEBEC TO 
THE CANADIAN MARITIMES TODAY. STRONG WESTERLY WINDS WILL CONTINUE IN 
THE WAKE OF THIS SYSTEM AIDED BY AMPLE INSTABILITY GENERATED BY MUCH 
COLDER AIR MOVING ACROSS THE MARINE AREAS.  THIS WILL ENSURE GALES 
WILL CONTINUE ACROSS THE OPEN AND NEARSHORE WATERS TODAY AND FRIDAY. 
   
THE GRADIENT WILL BEGIN TO RELAX THIS WEEKEND AS A RIDGE OF HIGH 
PRESSURE BUILDS INTO THE REGION.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.

LAKE HURON...
     GALE WARNING...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-LHZ464...UNTIL 10 
     PM FRIDAY.

     GALE WARNING...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON 
     INCLUDING SAGINAW BAY...UNTIL 4 AM FRIDAY.

LAKE ST CLAIR...
     GALE WARNING...UNTIL 4 AM FRIDAY.

MI WATERS OF LAKE ERIE...
     GALE WARNING...UNTIL 4 AM FRIDAY.

     LOW WATER ADVISORY...UNTIL 10 PM THURSDAY.

&&

$$

AVIATION.....CB
UPDATE.......KURIMSKI
SHORT TERM...KURIMSKI
LONG TERM....HLO
MARINE.......KURIMSKI

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