Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 172300
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
700 PM EDT FRI APR 17 2015


.AVIATION...

WEAK HIGH PRESSURE OVER THE AREA WILL LEAD TO A DECREASE IN WIND
SPEEDS SHORTLY AFTER 00Z AND A LOSS OF THE ALTO CU FIELD. A COLD
FRONT NOW APPROACHING LAKE SUPERIOR FROM THE NORTHWEST WILL TRACK
ACROSS SE MI TOWARD DAYBREAK SAT. DRY LOW LEVEL AIR IN THE VICINITY
OF THIS FRONT WILL INHIBIT LOW CLOUD FORMATION. THERE WILL BE AN
ABRUPT WIND SHIFT TO THE NORTHEAST AND INCREASE IN WIND SPEEDS IN
THE WAKE OF THE FRONT...EXPECTED TO IMPACT THE TERMINALS LATE SAT
MORNING...WITH NE WINDS PERSISTING THROUGH THE AFTERNOON.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

.PREV DISCUSSION...ISSUED 340 PM EDT FRI APR 17 2015

SHORT TERM...THIS AFTERNOON THROUGH TONIGHT

SCATTERED DIURNALLY DRIVEN CUMULUS WILL ERODE QUICKLY THIS EVENING
WITH THE LOSS OF DAYTIME HEATING...LEADING TO CLEAR SKIES TONIGHT.
IN TURN...WITH LIGHT WINDS...THESE CLEAR SKIES WILL ALLOW MINIMUM
TEMPERATURES TO DROP BACK WELL INTO THE 40S IN MOST LOCATIONS...EVEN
AFTER TOPPING OUT IN THE LOWER TO MID 70S LATE THIS AFTERNOON. ONLY
THE INNER HEAT ISLAND OF METRO DETROIT WILL HOLD CLOSER TO 50F.

LONG TERM...SATURDAY THROUGH NEXT FRIDAY

COLD FRONT TRAILING LOW PRESSURE MOVING FROM ONTARIO INTO QUEBEC
WILL DROP THROUGH SOUTHEAST MICHIGAN EARLY IN THE DAY...BEFORE
SETTLING TO OUR SOUTH AND WEST. THIS WILL BRING GUSTY NORTHEAST
WINDS FOR THE FIRST PART OF THE DAY...AND USHER COOLER LAKE-MODIFIED
AIR FROM LAKE HURON WELL INLAND. TEMPERATURES WILL VARY WIDELY
ACROSS SOUTHEAST MICHIGAN...WITH HIGHS NEAR 50 ALONG THE SHORELINE
OF THE NORTHERN THUMB RANGING TO NEAR 70 ALONG THE I-94 CORRIDOR.
AIRMASS ALSO LOOKS VERY DRY AS DEWPOINTS FALL INTO AND THROUGH THE
30S ON THE NORTHEAST SIDE OF THE FRONT. THIS SHOULD DROP RH DOWN
INTO THE 25 TO 30 PERCENT RANGE FOR MOST OF THE AREA. HIGH PRESSURE
WILL QUICKLY BUILD IN BEHIND THE FRONTAL PASSAGE DURING THE AFTERNOON
AND EVENING...AND WILL LEAD TO A QUIET AND MOSTLY SUNNY DAY OVERALL.

MORE CHALLENGING FORECAST SCENARIO THEN DEVELOPING BY SUNDAY/SUNDAY
NIGHT. NORTHERN STREAM ENERGY NOW PUSHING THROUGH BRITISH COLUMBIA
WILL DROP INTO CENTRAL CANADA AND THE NORTHERN PLAINS BY SUNDAY
MORNING. THE CUT-OFF LOW OVER THE FOUR CORNERS IS SHOWN BY MODELS TO
PHASE WITH THIS WAVE...WHILE ANOTHER SHORTWAVE NOW ENTERING
CHIHUAHUA (MEXICO) IS FORECAST TO LIFT UP AHEAD OF THESE MERGING
FEATURES...AND INTO MICHIGAN SUNDAY AFTERNOON INTO SUNDAY NIGHT.
THIS SHOULD RESULT IN A DOUBLE-BARRELED SURFACE LOW DEVELOPING OVER
THE UPPER MIDWEST AND CENTRAL GREAT LAKES...WITH A DEEPENING SYSTEM
EXPECTED AS HEIGHTS FALL WITH ALL THE MERGING ENERGY AND AS THE
RIGHT ENTRANCE REGION OF AN UPPER JET BECOMES POSITIONED OVERHEAD.
CURRENT SURFACE LOW TRACK FORECAST IS UP THROUGH WESTERN MICHIGAN
SUNDAY NIGHT...BUT CONFIDENCE IN MODEL SOLUTIONS WITH THE TRACK AND
STRENGTH IS NOT HIGH. THIS IS DUE IN PART TO LOW CONFIDENCE WITH CUT-
OFF FEATURES OVERALL. STRONG SOUTHERLY FLOW PRECEDING THE APPROACH
OF THIS SYSTEM SHOULD FEED GOOD MOISTURE UP INTO MICHIGAN...WITH
H850 DEWPOINTS RISING BETWEEN 6-8C AND OVERALL PW RISING TO ABOVE AN
INCH. THIS SHOULD PROVIDE A GOOD AREA OF RAINFALL SUNDAY AFTERNOON
INTO SUNDAY NIGHT AS A WARM FRONT LIFTS THROUGH THE AREA. KEPT POPS
IN THE HIGH LIKELY CATEGORY JUST DUE TO UNCERTAINTY...BUT EXPECTING
A WET AND BREEZY DAY OVERALL.

THE LOW PRESSURE ASSOCIATED AFFECTING THE GREAT LAKES REGION WILL BE
CONTINUING TO MOVE NORTH OVER THE NORTHERN GREAT LAKES DURING THE
DAY ON MONDAY.  THIS WILL BRING UNSETTLED WEATHER TO THE AREA FOR
THE START OF NEXT WEEK WITH RAIN AND THUNDERSTORMS POSSIBLE MONDAY
AS A COLD FRONT SLIDES ACROSS THE AREA MONDAY.  AHEAD OF THE
FRONT...TEMPERATURES ARE EXPECTED TO RISE UP INTO THE LOWER 60S.
TEMPERATURES THEN COOL OFF BACK INTO THE UPPER 40S TO LOWER 50S FOR
HIGHS THROUGH THE MIDDLE OF THE WEEK AS SOUTHEAST MICHIGAN RESIDES
IN A LONG WAVE TROUGH.  THIS PERSISTENT TROUGHING STICKS AROUND
THROUGH THE MAJORITY OF THE WEEK

MARINE...

QUIET CONDITIONS ARE EXPECTED FOR THE REMAINDER OF TODAY AND MOST OF
TONIGHT. A LOW PRESSURE SYSTEM TRACKING FROM ONTARIO INTO QUEBEC
WILL PUSH A COLD FRONT DOWN ACROSS THE CENTRAL GREAT LAKES VERY LATE
TONIGHT AND EARLY SATURDAY. THIS WILL CAUSE WINDS TO SHIFT TO A
NORTHERLY DIRECTION AND INCREASE IN SPEED...WITH GUSTS NEAR 20
KNOTS. WAVES ARE ALSO EXPECTED TO BUILD NEAR 3 FEET OVER THE
NEARSHORE AREAS OF LAKE HURON LATE EARLY SATURDAY. WINDS AND WAVE
HEIGHTS WILL DECREASE IN THE AFTERNOON AS STRONG HIGH PRESSURE
BUILDS INTO MICHIGAN AND ONTARIO.

A LOW PRESSURE SYSTEM WILL LIFT ACROSS THE AREA SUNDAY AND
MONDAY...BRINGING A PERIOD OF WET WEATHER AND GUSTY WINDS. WINDS ARE
EXPECTED TO INCREASE FROM THE EAST AND THEN SOUTHEAST ON
SUNDAY...WITH SUSTAINED SPEEDS EXPECTED TO REACH 20 KNOTS OR GREATER
SUNDAY EVENING. THIS WILL LIKELY NECESSITATE AT LEAST SMALL CRAFT
ADVISORIES FOR THE NEARSHORE AREAS SUNDAY INTO MONDAY. GALE FORCE
WINDS ARE POSSIBLE BUT NOT LIKELY AT THIS TIME. THERE IS STILL
HOWEVER SOME UNCERTAINTY WITH THE STRENGTH AND TRACK OF THE LOW
PRESSURE SYSTEM...AND CHANGES TO THE FORECAST ARE POSSIBLE.

&&

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

$$

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


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


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