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000
FXUS63 KDTX 052309
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
609 PM EST THU DEC 5 2013


.AVIATION...

//DISCUSSION...

W-SW WINDS WILL CONTINUE TO DIMINISH THIS EVENING WITH A WEAKENING
GRADIENT AND ONSET OF NOCTURNAL COOLING. THE POST FRONTAL MVFR
STRATO CU FIELD HAS CLEARED OUT...LEAVING ONLY HIGH CLOUDS AT THE
TAF SITES. LOW PRESSURE MOVING THROUGH THE OHIO VALLEY WILL BRING
LOWER CLOUDS INTO THE SOUTHERN GREAT LAKES...MAINLY AFFECTING THE
METRO AIRPORTS FRIDAY AFTERNOON. THESE CLOUDS ARE ONLY EXPECTED TO
LOWER BASES TO 4K FEET.

//DTW THRESHOLD THREATS...

* NONE.

&&

.PREV DISCUSSION...ISSUED 350 PM EST THU DEC 5 2013

SHORT TERM...TONIGHT

THE ARCTIC AIRMASS RESIDING OVER THE UPPER MIDWEST WILL CONTINUE TO
GRADUALLY ADVANCE INTO SE MI THIS EVENING THROUGH TONIGHT. DESPITE
THE WESTERLY FLOW...THE DEGREE OF DRY AIR IS LIMITING THE MOISTURE
FLUX OFF LAKE MI. THIS HAS BEEN ALLOWING A FAIR AMOUNT OF
CLEARING...ESPECIALLY ACROSS THE SAGINAW VALLEY. ALTHOUGH CLEARING
OF THE LOW CLOUDS WILL CONTINUE THROUGH THE EVENING GIVEN THE
PERSISTENT LOW LEVEL DRY AIR ADVECTION...THERE IS A CONSIDERABLE
AMOUNT OF MID/HIGH CLOUDS TO THE SOUTHWEST. THESE CLOUDS ARE
OCCURRING WITHIN A REGION OF MID LEVEL FRONTOGENSIS WHICH WILL
OVERSPREAD LOWER MI THIS EVENING AND PERSIST INTO FRI MORNING. THE
MORE ACTIVE PORTION OF THIS FRONTAL ZONE WILL REMAIN WELL TO THE
SOUTH TONIGHT...KEEPING SE MI DRY. THE MID/HIGH LEVEL CLOUDS WILL
HOWEVER ADVANCE INTO THE AREA DURING THE COURSE OF THE NIGHT.
ALTHOUGH THE CLOUD COVER AND WESTERLY GRADIENT WILL LIMIT THE DEGREE
OF RADIATIONAL COOLING TONIGHT...THE LOW LEVEL COLD AIR ADVECTION
WILL BE STRONG ENOUGH TO DROP TEMPS WELL DOWN INTO THE 20S. WIND
CHILL READINGS WILL DROP INTO THE TEENS.

LONG TERM...FRIDAY THROUGH NEXT THURSDAY

FIRST ISSUE IN THE EXTENDED WILL BE TO DETERMINE IF A LOW PRESSURE
SYSTEM TRACKING UP THROUGH THE TENNESSEE VALLEY WILL SPREAD SNOW AS
FAR NORTH AS SOUTHEAST MICHIGAN FRIDAY AFTERNOON AND EVENING.
EURO/GFS/NAM ALL SHOW THE 850 MB FRONT ON THE NORTH SIDE OF THE
SYSTEM JUST BARELY CLIPPING EXTREME SOUTHEAST MICHIGAN...AND SHOW
THE 700MB FRONT BECOMING SITUATED OVERHEAD. ISENTROPIC ASCENT WITHIN
THESE LAYERS (290K AND 295K) LOOKS RELATIVELY WEAK AND THETA-E
ADVECTION IS PRETTY MUCH NON-EXISTENT THIS FAR NORTH. BY
COMPARISON...ASCENT AND MOISTURE ADVECTION LOOK VERY STRONG TO OUR
SOUTH ALONG THE LOW-LEVEL FRONT...PARTICULAR FROM SOUTHERN
INDIANA/OHIO INTO KENTUCKY/WEST VIRGINIA. SITUATION LOOKS MORE
PROMISING FOR LOWER-LEVELS OF THE FRONT TO ACTIVATE AND THINK WE
WILL SEE LITTLE SNOW IF ANY OVER FAR SOUTHEAST MICHIGAN FROM THIS
SYSTEM. BEST POTENTIAL FOR A DUSTING OF SNOW WILL BE OVER MONROE
COUNTY. LOW POPS DO REMAIN IN THE FORECAST FROM DETROIT SOUTHWARD TO
COVER THE POTENTIAL FOR SOME LIGHT SNOW TO SPILL INTO
MICHIGAN...FURTHER SHIFTS IN THE STORM TRACK...AND TO ACCOUNT FOR
ANY EFFECT A WEAK UPPER WAVE TRACKING THROUGH MICHIGAN COULD HAVE.
MODELS ALL SHOW THIS WAVE TRACKING THROUGH LOWER MICHIGAN DURING THE
AFTERNOON AND EVENING. FRONTOGENTIC RESPONSE COULD BE JUST STRONG
ENOUGH TO SQUEEZE OUT SOME LIGHT SNOW OVER FAR SOUTHERN MICHIGAN AND
FLURRIES FOR THE REMAINDER OF THE AREA. OVERALL...EXPECT PLENTY OF
CLOUD COVER AROUND WITH THE INCREASE IN MID/HIGH LEVEL MOISTURE.
COOL AIRMASS WILL ALSO REMAIN IN PLACE CONFINING HIGH TEMPERATURES
IN THE MID 20S TO LOW 30S.

UPPER WAVE NOW OVER SASKATCHEWAN WILL TRACK ACROSS THE NORTHERN
GREAT LAKES SATURDAY INTO SATURDAY NIGHT...WHILE STRONG SURFACE HIGH
PRESSURE BUILDS IN FROM THE WEST. GFS/NAM FORECAST SOUNDINGS SHOW
MUCH DRIER AIR PUSHING INTO THE REGION SATURDAY AND ESPECIALLY
SATURDAY NIGHT...WITH ONLY A LITTLE MOISTURE TRAPPED UNDER A FALLING
INVERSION (ALL BELOW 850MB) BY SATURDAY MORNING. A LITTLE HESITANT
TO ACCEPT THE ATMOSPHERE WILL BE THIS DRY GIVEN CONTINUED WESTERLY
FLOW OFF LAKE MICHIGAN. KEPT SOME CLOUDS AROUND FOR SATURDAY WITH
CLEARING OVERNIGHT AS MOISTURE WANES FURTHER AND HIGH PRESSURE DROPS
INVERSIONS QUITE LOW OVER THE LAKE. OVERNIGHT MIN TEMPS FOR THE
WEEKEND WILL BE QUITE COLD...WITH MOST AREAS IN THE TEENS BOTH
FRIDAY NIGHT AND SATURDAY NIGHT.

A LOW PRESSURE SYSTEM WILL BE APPROACHING THE GREAT LAKES REGION
LATE SUNDAY WITH MODELS CURRENTLY SHOWING THE LOW TRACKING ACROSS
THE CENTRAL GREAT LAKES. SOUTHEAST MICHIGAN LOOKS TO BE IN THE COLD
SECTOR...SO SNOW WILL BE THE MAIN PRECIP TYPE.  ONE CAVEAT WITH THIS
SYSTEM HOWEVER IS THE LIMITED MOISTURE AS THE BETTER MOISTURE
APPEARS TO STAY TO THE SOUTH.  THIS SYSTEM WILL CONTINUE TO PUSH OFF
TO THE NORTHEAST ON MONDAY BRINGING CAA TO THE AREA.  RIDGE OF HIGH
PRESSURE THEN BUILDS IN BEHIND THE DEPARTING SYSTEM JUST AS A WEAK
DISTURBANCE LOOKS TO DIG DOWN ACROSS THE NORTHERN MIDWEST AND GREAT
LAKES. WITH WESTERLY FLOW ONGOING...POTENTIAL WILL EXIST FOR SNOW
SHOWERS GIVEN ENOUGH MOISTURE. A REINFORCING SHOT OF ARCTIC AIR IS
THEN SET TO OVERTAKE THE GREAT LAKES REGION TUESDAY/WEDNESDAY...WITH
HIGHS ONLY REACHING INTO THE UPPER TEENS TO LOWER 20S.

MARINE...

STRONG WESTERLY WINDS WILL CONTINUE OVER LAKE HURON INTO TONIGHT AS
A LOW PRESSURE SYSTEM DEEPENS OVER ST JAMES BAY. GALE FORCE WIND
GUSTS TO AROUND 35 KNOTS WILL CONTINUE NORTH OF ALABASTER BEFORE
WINDS GRADUALLY SUBSIDE FROM SOUTH TO NORTH TONIGHT AS THE AREA OF
LOW PRESSURE STARTS TO WEAKEN AND MOVE INTO QUEBEC. WIND GUSTS
BETWEEN 25 AND 30 KNOTS ARE EXPECTED OVER THE REMAINDER OF LAKE
HURON TONIGHT...AND SMALL CRAFT ADVISORIES REMAIN IN EFFECT FOR THE
NEARSHORE WATERS.

HIGH PRESSURE WILL BRING CALMER CONDITIONS TO MOST
OF THE AREA FOR FRIDAY AND INTO THE WEEKEND. SEVERAL UPPER LEVEL
DISTURBANCES MOVING THROUGH ONTARIO AND QUEBEC WILL KEEP WINDS MORE
ELEVATED OVER LAKE HURON HOWEVER. THE STRONGEST WINDS ARE EXPECTED
ON SATURDAY...BUT LOOK TO REMAIN JUST SHY OF GALE FORCE.

&&

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

LAKE HURON...
     GALE WARNING...LHZ361-LHZ362...UNTIL 5 AM FRIDAY.

     GALE WARNING...LHZ363...UNTIL 10 PM THURSDAY.

     SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS
     FROM PORT AUSTIN TO HARBOR BEACH...UNTIL 5 AM FRIDAY.

     SMALL CRAFT ADVISORY...INNER SAGINAW BAY...UNTIL 10 PM THURSDAY.

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

&&

$$

AVIATION.....KURIMSKI
SHORT TERM...SC
LONG TERM....HLO/SS
MARINE.......HLO


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