Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 300735
AFDDTX

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

.SHORT TERM...TODAY AND TONIGHT

SHORTWAVE RIDGING WILL TRACK EAST THROUGH THE CENTRAL GREAT LAKES
THIS MORNING...KEEPING WINDS CALM AND CONDITIONS RELATIVELY DRY
DURING THE DAYTIME HOURS. DESPITE MORNING SUNSHINE...CLOUDS WILL
INCREASE THROUGH THE DAY AS MOISTURE ADVECTS IN FROM THE WEST AHEAD
OF A DEVELOPING LOW PRESSURE SYSTEM DIVING SOUTH FROM CANADA TOWARDS
THE NORTHWESTERN GREAT LAKES THIS AFTERNOON. GIVEN THE MID AND UPPER
LEVEL WAVE WILL STILL BE FAR TO THE NORTHWEST...RAIN WITH THIS
SYSTEM IS NOT EXPECTED TO AFFECT THE AREA TODAY. WITH COLD AIR STILL
IN PLACE AND INCREASING CLOUDS...HIGHS WILL GENERALLY BE AROUND 50
DEGREES...WITH SOME MID 40S POSSIBLE OVER THE NORTHERN THUMB REGION.

THE POSITIVELY TILTED MID LEVEL TROUGH OVER THE NORTHWESTERN GREAT
LAKES WILL DIVE SOUTH OVER LAKE MICHIGAN TONIGHT AS THE SURFACE LOW
TRACKS FROM THE SOO TO CENTRAL LAKE HURON. THIS WILL DRAG A SURFACE
COLD FRONT THROUGH THE MIDDLE OF THE CWA LATE TONIGHT...BRINGING A
RENEWED CHANCE FOR RAIN TO THE AREA. THE REAL COLD AIR WITH THIS
FRONT WILL HOLD OFF A BIT...WITH ALL LIQUID PRECIPITATION EXPECTED
THROUGH THE OVERNIGHT HOURS AS SOUNDINGS SHOW A FAIRLY WARM BOUNDARY
LAYER THROUGH 12Z FRIDAY. THEREFORE WILL KEEP OUT MENTION OF SNOW
MIXING IN WITH THE RAIN THROUGH THE OVERNIGHT HOURS. ALTHOUGH THE
SURFACE FRONT WILL MAKE IT OVER THE WESTERN CWA LATE TONIGHT...THE
MAIN MID AND UPPER LEVEL DYNAMICS WILL LAG BEHIND THE FRONT A
BIT...AS EVIDENCED BY THE ABUNDANT AMOUNT OF POST FRONTAL
PRECIPITATION. GIVEN THESE FACTORS WILL CONTINUE WITH THE HIGH
LIKELY POPS ACROSS THE WEST TONIGHT AND NOT RAISE POPS TO
CATEGORICAL WITH THIS ISSUANCE. THE ABUNDANT CLOUD COVER AND RAIN
SHOWERS WILL KEEP THE DIURNAL RANGE TO A MINIMUM WITH LOWS AROUND 40
DEGREES TONIGHT GIVEN THE LAG OF COLD AIR BEHIND THE SURFACE COLD
FRONT.

&&

.LONG TERM...

LATEST WATER VAPOR IMAGERY SHOWS CENTER OF UPPER LEVEL CIRCULATION/
PV ANOMALY OVER NORTHERN MANITOBA...ADVANCING SOUTHEAST.
UNFORTUNATELY...THE 00Z MODELS (GFS/NAM/CANADIAN/EURO) STILL ARE NOT
IN GOOD AGREEMENT WITH THE TRACK AND CLOSING OFF OF THE 500 MB LOW.
NAM/GFS ARE CLOSING THE 500 MB OFF FASTER AND ARE FARTHER
EAST...OVER WESTERN HALF OF LOWER MICHIGAN...WHILE EURO REMAINS OPEN
A BIT LONGER AND IS MUCH FARTHER WEST...WITH THE CANADIAN BEING THE
FARTHER EAST...TRACKING IN BETWEEN THE CENTRAL/EASTERN GREAT LAKES.
REGARDLESS OF THE SOLUTION...A VERY TIGHT LOW LEVEL (925-850 MB)
BAROCLINIC ZONE OVER SOUTHEAST MICHIGAN SETTING UP...WITH THE
INCREASING NORTHEAST FLOW OFF THE WARM WATERS (LOWER 50S) OF LAKE
HURON FURTHERING STRENGTHENING OR AT THE VERY LEAST MAINTAINING
FRONTAL ZONE INTO FRIDAY NIGHT. SKEWING THE FORECAST A BIT TOWARD
THE NAM...WHICH HOPEFULLY CAN FACTOR IN THE MESOSCALE INFLUENCE OF
LAKE HURON A BIT BETTER...IT CONTINUES TO LOOK LIKE PREDOMINATELY
RAIN/NON-ACCUMULATING WET SNOW THROUGH THE DAY ON FRIDAY...AS NAM
MAINTAINS SURFACE DEW PTS COMFORTABLY ABOVE FREEZING THROUGH
21Z...WITH SIGNIFICANT DRYING THEN ATTEMPTING TO MAKE INROADS TOWARD
THE U.S. 23 CORRIDOR. EXPECTING PRECIPITATION TO CONTINUE EAST OF
U.S. 23 THROUGH FRIDAY NIGHT AS 850-700 MB MOISTURE/THETA-E RIDGE
SEEN ARCHING BACK FRIDAY EVENING WITH CONTINUED LAKE HURON
ENHANCEMENT TAKING PLACE BASED ON 850 MB TEMPS OF -5 TO -10 C. THE
STRONG INFLUENCE/FLOW OFF LAKE HURON LOOKS TO BE THE OVERRIDING
FACTOR IN THE EQUATION KEEPING SURFACE/NEAR SURFACE LAYER JUST WARM
ENOUGH TO PREVENT MUCH IN THE WAY OF SNOW ACCUMULATION AS BOTH
GFS/NAM INDICATING 925 MB TEMPS REMAINING ABOVE -3 C EAST OF U.S
23...WITH SURFACE DEW PTS STILL HOVERING AT OR ABOVE FREEZING. ALONG
AND WEST OF U.S. 23...DRY AIR WILL PROBABLY WIN OUT...ESPECIALLY IF
ONE IS TO BELIEVE THE EURO...BUT IF ANY PRECIPITATION DOES MAKE IT
THIS FAR WEST...LIGHT SNOW ACCUMULATIONS WILL BE POSSIBLE.

NORTHERLY WINDS WILL BE STRONG FRIDAY AFTERNOON/EVENING...BUT THERE
IS LITTLE IN THE WAY OF DOWNWARD MOMENTUM (PREDOMINATELY CONTINUED
POSITIVE LOW LEVEL ASCENT)...AND PRECIPITATION DRAG ISSUES TO
CONTEND WITH. RISE/FALL COUPLET WORKING THROUGH IS ALSO NOTHING
SPECIAL 10-12 MB...AND THUS EXPECTING GUSTS TO TOP OUT IN THE 35 TO
40 MPH RANGE...THE EXCEPTION WOULD BE RIGHT NEAR THE LAKE HURON
LAKESHORE WHERE HIGHER GUSTS ARE POSSIBLE.

AMPLIFIED UPPER LEVEL RIDGE WILL GRADUALLY BUILD INTO THE GREAT
LAKES REGION OVER THE WEEKEND....SHUTTING OFF THE LAKE EFFECT AND
ALLOWING TEMPERATURES TO ATTEMPT TO MODERATE. THE PROBLEM IS SURFACE
HIGH BUILD IN WILL ALLOW FOR SURFACE TEMPERATURES TO CRATER (20S)
SATURDAY NIGHT AS SKIES ARE EXPECTED TO BE MOSTLY CLEAR...AND
BOUNDARY LAYER MIXING ON SUNDAY WILL BE LIMITED...AS SUN
ANGLE/OVERALL INSOLATION DECLINES AS WE HEAD INTO NOVEMBER. 925 MB
FORECASTED (EURO)TEMPS TO CLIMB TO SLIGHTLY POSITIVE...SUPPORTIVE OF
MID 40S FOR HIGHS.

&&

.MARINE...
A RIDGE OF HIGH PRESSURE WILL MAINTAIN FAIRLY LIGHT WINDS AND LOW
WAVES TODAY. A STRONG LOW PRESSURE SYSTEM AND ARCTIC FRONT REMAINS
ON TRACK TO SWING INTO THE CENTRAL GREAT LAKES LATE TONIGHT.
NORTHERLY WINDS WILL BECOME STRONG BEHIND THE FRONT
FRIDAY AND FRIDAY NIGHT...WITH GUSTS LIKELY REACHING GALE FORCE OVER
MUCH OF LAKE HURON. THE STRONG PERSISTENT NORTHERLY WINDS
WILL ALLOW WAVE HEIGHTS TO BUILD IN EXCESS OF 10 FEET OVER
SOUTHERN LAKE HURON. WINDS WILL GRADUALLY DIMINISH ON SATURDAY AS
THE LOW MOVES EAST AND HIGH PRESSURE BUILDS INTO THE
AREA. HOWEVER...THE WAVES WILL BE SLOWER TO DECREASE...AND WILL
LIKELY NOT DROP BELOW 4 FEET UNTIL SATURDAY NIGHT.

&&

.AVIATION...ISSUED 1205 AM EDT THU OCT 30 2014

//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.

&&

.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.
&&

$$

SHORT TERM...KURIMSKI
LONG TERM....SF
MARINE.......SF
AVIATION.....BT


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



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