Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 300405
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1205 AM EDT THU OCT 30 2014

.AVIATION...

//DISCUSSION...

LATE EVENING OBSERVATIONS INDICATE SOME PATCHES OF MVFR STRATOCU
OVER NORTHERN LOWER THAT HAVE THE BEST CHANCE OF AFFECTING MBS AND
FNT DURING THE REST OF THE NIGHT. IT WILL BE DIFFICULT FOR THESE
CLOUDS TO DEVELOP TOWARD DTW BEFORE THE LOW LEVEL WIND BEGINS
BACKING TOWARD THE WEST. CLOUDS FROM LAKE MICHIGAN WILL THEN MAKE AN
EASTWARD MOVE...BUT THESE ARE EXPECTED TO REMAIN LOW END VFR THROUGH
THE MORNING. VFR CEILING WILL INCREASE COVERAGE DURING THE AFTERNOON
BEFORE LIGHT RAIN BECOMES POSSIBLE THURSDAY EVENING.

//DTW THRESHOLD THREATS...

* MODERATE CONFIDENCE IN CEILING BELOW 5000 FT PREVAILING FROM
  AROUND SUNRISE THROUGH THURSDAY EVENING.

&&

.PREV DISCUSSION...ISSUED 403 PM EDT WED OCT 29 2014

SHORT TERM...TONIGHT

LINGERING RAIN SHOWERS AND GUSTY WINDS ACROSS SOUTHEAST MICHIGAN
WILL BOTH COME TO AN END SHORTLY AFTER SUNSET. BRIEF RIDGING
OVERNIGHT WILL ALLOW WINDS TO BECOME MOSTLY CALM AND CLOUD COVER TO
DIMINISH SLIGHTLY AS DRY AIR FILTERS INTO THE REGION. WHILE THE DRY
AIR WILL KEEP LOW LEVEL CLOUDS FROM DEVELOPING...ENOUGH MID LEVEL
MOISTURE WILL STICK AROUND TO KEEP SOME MID CLOUDS IN THE FORECAST
GIVING WAY TO A PARTLY CLOUDY FORECAST OVERNIGHT. LOW TEMPERATURES
WILL BE MUCH COOLER THAN PREVIOUS NIGHTS...WITH LOWS DROPPING DOWN
INTO THE LOW TO MID 30S ACROSS SOUTHEAST MICHIGAN. THE METRO DETROIT
AREA HAS THE POTENTIAL TO BE SLIGHTLY WARMER WITH TEMPERATURES ONLY
DROPPING INTO THE UPPER 30S.

LONG TERM...THURSDAY THROUGH NEXT WEDNESDAY

SURFACE RIDGING WILL PERSIST THROUGH MUCH OF THURSDAY BEFORE
SHIFTING EAST. ALTHOUGH QUIET CONDITIONS ARE EXPECTED UNDER THE
RIDGE TOMORROW...CLOUDS WILL INCREASE THROUGH THE DAY AS MOISTURE
ARRIVES AHEAD OF A LOW PRESSURE SYSTEM DROPPING THROUGH CANADA...AND
AS THE UPPER WAVE OVER THE NORTHERN ROCKIES DIVES INTO MO/IL.
OVERALL...EXPECTING A MOISTLY CLOUDY DAY FROM THE AFTERNOON GOING
FORWARD. TEMPERATURES WILL REMAIN UNSEASONABLY COOL IN THE WAKE OF A
WEAK FRONT THAT PUSHED THROUGH EARLIER TODAY...WITH MAX TEMPERATURES
FROM THE MID 40S TO LOW 50S.

MAIN FOCUS IN THE EXTENDED WILL BE THE NEXT SYSTEM DROPPING THROUGH
AS IT WILL BRING WINDY CONDITIONS...EVEN COLDER TEMPERATURES...AND
OUR FIRST CHANCE FOR LIGHT SNOWFALL THIS SEASON. SEVERAL PIECES OF
ENERGY FROM WAY UP OVER THE NORTHWEST TERRITORIES AND NUNAVUT WILL
CONSOLIDATE AS THEY DIVE THROUGH CANADA AND AND THE WESTERN GREAT
LAKES LATE THURSDAY THROUGH FRIDAY. SURFACE LOW PRESSURE SYSTEM AND
COLD FRONT WILL DROP THROUGH LOWER MICHIGAN FRIDAY...WITH GFS/NAM
MODELS NOW TRENDING TOWARDS THE TIMING OF THE EURO/GEM. THIS LOOKS
TO PUSH THE COLD FRONT THROUGH EARLY IN THE DAY...MAINLY BETWEEN 14Z
AND 20Z. FGEN FORCING AND STRONG PVA WILL WORK WITH A MODEST THETA-E
PLUME SURGING UP AHEAD OF THE SYSTEM TO GENERATE WIDESPREAD SHOWERS.
MAIN ISSUE WILL BE THE VERY COLD AIR COMING IN WITH THE ARCTIC FRONT
AND HOW SOON PRECIPITATION WILL CHANGE FROM RAIN TO SNOW. CHANGEOVER
WILL OCCUR FROM NORTHWEST TO SOUTHEAST THROUGH THE DAY (MAX TEMPS
WILL BE REACHED EARLIER IN THE DAY FOR ALL BUT THE DETROIT AREA)
.LOOKING TO START BY MID-MORNING NEAR THE SAGINAW VALLEY AND
FINALLY SWITCH OVER NEAR THE CITY OF DETROIT DURING THE EARLY
EVENING. EXPECTING MOSTLY SNOW BY 800 PM...WITH POTENTIALLY AN
EXCEPTION IMMEDIATELY ALONG THE SHORE OF LAKE HURON WHERE WINDS WILL
BE OFF THE WARMER WATER.

MOISTURE WILL START TO PULL AWAY AS THE LOW EXITS EAST
HOWEVER...KEEPING SNOW AMOUNTS FAIRLY LIGHT. WILL HAVE TO
CONTINUALLY REASSESS THIS WITH EACH RUN OF NEW MODEL DATA HOWEVER.
STILL SOME UNCERTAINTY AS TO HOW MUCH WILL ACTUALLY STICK ON THE
GROUND WITH WARM ROAD TEMPERATURES AND PAVEMENT. BEST CHANCE FOR
LIGHT ACCUMULATIONS (A FEW TENTHS LOOK BEST RIGHT NOW) WILL BE ON
ELEVATED AND GRASSY SURFACES. STRONG WINDS WILL ALSO ACCOMPANY THE
FRONT AS THE ARRIVAL OF COLDER AIR STEEPENS LAPSE RATES AND DEEPENS
THE BOUNDARY LAYER. FORECAST SOUNDINGS SUGGEST GUSTS TO 40 MPH...BUT
WILL NEED TO WATCH THE STRONGER EURO MODEL...WHICH HAS A CORE OF 40-
50 KNOTS AS LOW AS 925 MB. TEMPERATURES WILL BECOME QUITE CHILLY BY
FRIDAY EVENING...ESPECIALLY WHEN THE GUSTY WINDS ARE FACTORED IN.
EVENING WIND CHILLS LOOK TO RUN BETWEEN THE MID 20S TO LOW 30S. THIS
IS IN ADDITION TO LINGERING RAIN AND SNOW SHOWERS.

LAKE EFFECT RAIN/SNOW SHOWERS WILL BE POSSIBLE DURING THE EVENING
AND OVERNIGHT OFF LAKE HURON AFTER THE LOW PULLS AWAY...WITH STEEP
LAPSE RATES OVER THE WATER AND PERSISTENT NORTHERLY FLOW OFF THE
LAKE. THIS MAY BRING ADDITIONAL LIGHT ACCUMULATIONS.

THE WEEKEND REMAINS VERY COLD IN THE EXTENDED FORECAST. COLD AIR
ADVECTION DOES SLOW DOWN...BUT THE 0-1KM LAPSE RATES OVER LAKE HURON
WILL BE IN THE 3 TO 5 K/KM RANGE WHICH WILL SPARK SOME LAKE EFFECT
SNOW SHOWERS. THE DELTA T WILL SHRINK AS THE DAY WEARS ON AND
SURFACE HIGH PRESSURE ENTERING FROM THE WEST WILL SHUT DOWN ANY LAKE
EFFECT PROCESSES AFTER NOON. AN UPPER RIDGE WILL START TO BUILD IN
SUN-MON AND PROVIDE A WARMING TREND. THIS TREND SHOULD SURVIVE THE
NEXT LOW PRESSURE AND COLD FRONT EARLY NEXT WEEK AS 500 MB HEIGHTS
ONLY BRIEFLY DROP BELOW 560 DAM.

MARINE...
GUSTY WEST WINDS WILL CONTINUE TO SUBSIDE THIS EVENING AS LOW
PRESSURE OVER NORTHERN QUEBEC CONTINUES TO LIFT NORTHEAST AND A
RIDGE OF HIGH PRESSURE BUILDS INTO THE AREA. THE RIDGE WILL KEEP
WINDS FAIRLY LIGHT AND WAVE HEIGHTS FAIRLY LOW THROUGH THURSDAY
EVENING. A LOW PRESSURE SYSTEM AND ARCTIC COLD FRONT WILL THEN DROP
SOUTHEAST THROUGH THE CENTRAL GREAT LAKES VERY LATE THURSDAY NIGHT
THROUGH FRIDAY. NORTHERLY WINDS WILL BECOME STRONG BEHIND THE FRONT
FRIDAY AND FRIDAY NIGHT...WITH GUSTS LIKELY REACHING GALE FORCE OVER
MUCH OF LAKE HURON. A GALE WATCH MAY ALSO BE NEEDED FOR LAKE ST
CLAIR AND WESTERN LAKE ERIE. THE STRONG PERSISTENT NORTHERLY WINDS
WILL ALLOW WAVE HEIGHTS TO BUILD AS HIGH AS 14 FEET OVER THE
SOUTHERN PORTION OF LAKE HURON. WINDS WILL GRADUALLY DIMINISH ON
SATURDAY AS THE LOW MOVES EAST AND HIGH PRESSURE BUILDS INTO THE
AREA...HOWEVER LARGE WAVES WILL PERSIST OVER THE SOUTHERN PORTION OF
LAKE HURON THROUGH SATURDAY.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...NONE.

LAKE HURON...GALE WATCH FROM FRIDAY MORNING THROUGH SATURDAY MORNING FOR LHZ362-
     363-421-422-441-462.

     GALE WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY MORNING FOR
     LHZ442-443-463-464.

LAKE ST CLAIR...NONE.

MICHIGAN WATERS OF LAKE ERIE...NONE.
&&

$$

AVIATION.....BT
SHORT TERM...RK
LONG TERM....HLO/MM
MARINE.......HLO


YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).



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