Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 240733
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
333 AM EDT FRI OCT 24 2014

.SHORT TERM... TODAY AND TONIGHT

ONE BATCH OF ELGONATED SOUTH-NORTH MOISTURE (PW VALUES AROUND 0.75
INCHES) IS MOVING THROUGH LOWER MICHIGAN EARLY THIS MORNING...AS A
FORMIDABLE SHORTWAVE IS TRACKING THROUGH FAR SOUTHERN LAKE MICHIGAN
AND INTO THE OHIO VALLEY. SHORTWAVE RIDGING WILL BUILD IN BEHIND
THIS UPPER WAVE TODAY OVER SOUTHERN LOWER MICHIGAN. 925 MB TEMPS
FORECASTED TO RISE TO 10 C...PER BOTH 00Z GFS AND NAM. THIS SUGGESTS
TODAY WILL BE A BIT WARMER...LOWER 60S/AROUND 60...BUT THERE IS SOME
HESITATION WITH AMOUNT OF LOW LEVEL MOISTURE/CLOUDS AROUND.

NEXT SURGE OF MOISTURE WILL ARRIVE VERY LATE TONIGHT AHEAD OF
APPROACHING COLD FRONT...AS THE UPPER LEVEL ENERGY RACES ACROSS FAR
SOUTHERN CANADA TODAY. THERE IS LITTLE IF ANY HEIGHT FALLS OCCURRING
OVER THE SOUTHERN GREAT LAKES THROUGH 12Z SATURDAY...AND WITH 1000-
500 MB MEAN RH REMAINING LESS THAN 60 PERCENT...PLANNING ON
MAINTAINING THE DRY FORECAST. WITH THE INCREASING SOUTHWEST GRADIENT
AND CONTINUED MODEST LOW LEVEL WARM ADVECTION OVERNIGHT...PLANNING
ON HOLDING MINS IN THE MID 40S.

&&

.LONG TERM...SATURDAY THROUGH THURSDAY

A STRUNG OUT DRY LOW PRESSURE SYSTEM...CURRENTLY SEEN ON WATER VAPOR
IMAGERY OVER THE WESTERN US/CANADIAN BORDER...WILL CONTINUE TRACKING
EAST DURING THE NEXT COUPLE OF DAYS...EVENTUALLY TRACKING THROUGH
THE NORTHERN GREAT LAKES REGION ON SATURDAY. THIS SYSTEM WILL BRING
A WEAK COLD FRONT THROUGH THE AREA AS IT PASSES TO THE NORTH AND NOT
MUCH ELSE. DESPITE THE MODELS SPITTING OUT SOME QPF WITH THIS
SYSTEM...MODEL SOUNDINGS ARE VERY DRY WITH LITTLE IN THE WAY OF LIFT
AS THE MAIN SHORTWAVE WILL BE WELL TO THE NORTH. EXPECTATIONS WITH
THIS SYSTEM ARE FAIRLY LOW...WITH CLOUDS AND SOME GUSTY WINDS BEING
THE MAIN THREAT AS THE AFOREMENTIONED WEAK COLD FRONT PASSES THROUGH
ON SATURDAY.

RIDGING WILL BRING DRY...QUIET WEATHER TO THE CENTRAL GREAT LAKES ON
SUNDAY WITH SLIGHTLY COOLER TEMPERATURES BEHIND THE WEAK COLD FRONT
DESPITE ABUNDANT SUNSHINE. AN APPROACHING LOW WILL BRING INCREASING
CLOUDS SUNDAY NIGHT AND MONDAY AS A WARM FRONT LIFTING NORTH BRINGS
THE CHANCE FOR SHOWERS ACROSS THE SAGINAW VALLEY AND THUMB REGION ON
MONDAY.

A DEEPER MID LEVEL TROUGH AND ATTENDANT SHORTWAVE WILL BRING
INCREASED CHANCES FOR RAIN MONDAY NIGHT AND TUESDAY AS INCREASED
TOTAL TOTALS AND K-INDEX VALUES BRING THE THREAT FOR A FEW RUMBLES
OF THUNDER DURING THIS PERIOD WITH INCREASED INSTABILITY. THE NWP
MODELS HAVE COME INTO BETTER AGREEMENT REGARDING THE HIGHEST CHANCE
OF RAIN ON TUESDAY WITH THIS SYSTEM...THEREFORE HAVE RAISED POPS
DURING THIS PERIOD TO REFLECT THE GREATER DEGREE OF CONFIDENCE.

TEMPERATURES COOL DOWN SEVERAL DEGREES BEHIND THE FRONT WEDNESDAY
AND THURSDAY...AS RIDGING KEEPS THE WEATHER QUIET DURING THE MIDDLE
TO LATER PART OF THE WORK WEEK.

&&

.MARINE...

A TRANQUIL WIND REGIME WILL GIVE WAY TO DEVELOPING MODERATE
SOUTHWEST FLOW ON SATURDAY IN ADVANCE OF AN APPROACHING SYSTEM. THE
ASSOCIATED COLD FRONT WILL TRAVERSE AREA WATERS SATURDAY AFTERNOON
INTO SUNDAY EVENING. WINDS WILL QUICKLY TURN NORTHWEST AND BECOME
FRESH TO STRONG...ESPECIALLY OVER THE OPEN WATERS OF CENTRAL LAKE
HURON...WITH GUSTS TO NEAR 30 KNOTS LIKELY OVER THE NORTHERN HALF OF
LAKE HURON ON SATURDAY NIGHT. A GUSTY MODERATE TO FRESH NORTHWEST
BREEZE WILL THEN PERSIST ACROSS THE WATERS THROUGH SUNDAY.

&&

.AVIATION...ISSUED 1154 PM EDT THU OCT 23 2014

//DISCUSSION...

CLOUDS WILL GRADUALLY INCREASE IN COVERAGE AND LOWER IN HEIGHT
DURING THE COURSE OF THE MORNING AS HIGH PRESSURE EXITS TO THE EAST
AND A SURFACE TROUGH APPROACHES FROM THE WEST. GIVEN THE WEAKENING
FORCING ASSOCIATED WITH THE APPROACHING SYSTEM AND THE ABUNDANCE OF
LOW LEVEL DRY AIR STILL IN PLACE ACROSS SE MI...NO PRECIP IS
EXPECTED THROUGH THE TAF PERIOD AND DROP IN CEILINGS SHOULD BE A
VERY GRADUAL PROCESS...WITH MVFR CONDITIONS POSSIBLY NOT TRACKING
INTO THE AREA UNTIL AFTERNOON OR EVENING.

FOR DTW...GIVEN THE CLOSER PROXIMITY TO THE DRY AIRMASS AND BASED ON
THE 00Z MODEL SOUNDINGS...CLOUDS BASES MAY HOLD ABOVE 5000 FT RIGHT
THROUGH THE MORNING.

//DTW THRESHOLD THREATS...

* LOW CONFIDENCE ON CEILINGS BELOW 5000 FEET LATE THIS
  MORNING...MEDIUM CONFIDENCE THIS AFTERNOON.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.

&&

$$

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


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



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