Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 221955
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
355 PM EDT FRI MAY 22 2015

.SHORT TERM...TONIGHT

QUIET WEATHER CONDITIONS WILL REMAIN THROUGH TONIGHT AS A SURFACE
HIGH PRESSURE SYSTEM BUILDS INTO THE GREAT LAKES REGION. WINDS WILL
DECREASE OVERNIGHT WITH CLEAR SKIES REMAINING IN PLACE...RESULTING
IN FROSTY CONDITIONS ACROSS PARTS OF THE CWA /MAINLY NORTH OF M-59/.
BEST LOCATIONS TO SEE WIDESPREAD FROST DEVELOPMENT WILL BE ACROSS
THE CENTRAL THUMB REGION AS WELL AS MIDLAND AND BAY COUNTIES WHERE
TEMPERATURES ARE EXPECTED TO DROP DOWN TO NEAR 33 TO 34 DEGREES. ALL
OTHER AREAS NORTH OF M-59 WILL LIKELY ONLY SEE AREAS OF FROST WITH
PLACES SOUTH OF M-59 AND INTO NORTHERN WASHTENAW AND WAYNE COUNTIES
ONLY SEEING PATCHY FROST. THE METRO DETROIT AREA AND SOUTHERN
COUNTIES WILL EXPERIENCE TEMPERATURES DROPPING INTO THE 40S...WHICH
WILL BE TOO WARM FOR ANY FROST TO DEVELOP. THEREFORE HAVE GONE AHEAD
AND ISSUED A FROST ADVISORY FOR THE LIVINGSTON/OAKLAND/MACOMB
COUNTIES NORTHWARD.

&&

.LONG TERM... SATURDAY THROUGH FRIDAY

TEMPERATURES WILL BOUNCE OFF FROSTY MORNING LOWS SATURDAY MORNING
AS SURFACE HIGH PRESSURE BECOMES CENTERED OVER PENNSYLVANIA. THE
LOCATION OF THE HIGH WILL BE A GOOD MARKER FOR THE LOW LEVEL
THERMAL TROUGH EXTENDING FROM THERE INTO EASTERN CANADA DURING THE
DAY. THIS WILL RESULT IN WEAK WARM ADVECTION OVER SE MICHIGAN
SURFACE TO 850 MB...WHICH WILL BE ABOUT THE DEPTH OF THE MIXED
LAYER BY MID AFTERNOON ACCORDING TO MODEL SOUNDINGS. NO PROBLEM
WITH TEMPERATURE GUIDANCE ALLOWING HIGHS TO REACH THE LOWER 70S
INLAND FROM THE SHORELINES GIVEN SUNSHINE WILL BE PLENTIFUL ACROSS
THE REGION. THE MILD AFTERNOON TEMPERATURES WILL CARRY OVER INTO
SATURDAY NIGHT AS THICKENING HIGH CLOUDS AND LIGHT SOUTH WIND ONLY
ALLOW MIN TEMPS IN THE UPPER 40S TO LOWER 50S.

THE INCREASING HIGH CLOUDS SATURDAY NIGHT WILL BE THE FIRST SIGN OF
CONDITIONS BECOMING UNSETTLED IN TERMS OF SHOWERS AND THUNDERSTORMS
SUNDAY THROUGH MONDAY. THE 12Z MODEL PACKAGE IS IN GOOD AGREEMENT
REGARDING THE LARGE SCALE WEATHER FEATURES INVOLVED IN THE
TRANSITION FOR SE MICHIGAN. HIGH CLOUDS SATURDAY NIGHT WILL BE
INITIALLY ASSOCIATED WITH THE REMNANTS OF THE UPPER WAVE OVER THE
CENTRAL PLAINS TODAY. THESE CLOUDS WILL BE AUGMENTED BY DEEPER
SOUTHWEST FLOW AND MOISTURE TRANSPORT TOWARD SUNRISE SUNDAY AS THE
LONG WAVE PATTERN EVOLVES EASTWARD. THE UPPER LEVEL RIDGE AXIS WILL
REMAIN TO OUR WEST THROUGH THE DAY BUT AN ENTRANCE REGION OF THE
UPPER JET WILL ORGANIZE OVER THE NORTHERN GREAT LAKES THROUGH THE
DAY. THIS WILL ENHANCE A WING OF ISENTROPIC ASCENT OVER CENTRAL AND
NORTHERN LOWER MICHIGAN ASSOCIATED WITH THE MID LEVELS OF THE THE
WARM FRONT ORGANIZING FROM THE MIDWEST INTO THE OHIO VALLEY. THE
SOUTHWARD EXTENT OF THE ASSOCIATED RAINFALL PATTERN IS WHERE THE
MODELS DISAGREE THE MOST. EXPECT THE UPPER LEVEL RIDGE AXIS WILL
SHIELD ALL BUT THE TRI CITIES AND NORTHERN THUMB FROM A CHANCE OF
RAIN DURING THE DAY. EASTWARD PROGRESSION OF THE RIDGE SUNDAY NIGHT
WILL THEN OPEN THE DOOR ON INCREASED SHOWER PROBABILITY OVER ALL
AREAS AS MOISTURE TRANSPORT BECOMES MORE OPEN AND THE SURFACE WARM
FRONT CLOSES IN ON THE AREA.

MONDAY THROUGH FRIDAY: THE WARM AND INCREASINGLY MOIST PATTERN IS
EXPECTED TO MAINTAIN THROUGH THE MIDDLE OF NEXT WEEK AND POSSIBLY
INTO FRIDAY. THIS WILL OCCUR AS SOUTH TO NORTH FLOW CONTINUES ON THE
BACK SIDE OF THE EASTWARD-MOVING HIGH. THE BROAD AREA OF LOWER
PRESSURE OVER THE GREAT PLAINS LIFTS NORTH OVER DAKOTAS MONDAY. THE
PATTERN APPEARS SOMEWHAT ENTRENCHED IN TERMS OF WARM AIR ADVECTION
AND WILL BE PERSISTENT WITH THE INFLUX OF GULF MOISTURE INTO THE
GREAT LAKES REGION THROUGH THE PERIOD. IT IS DIFFICULT TO PINPOINT
PRECIP TIMING FOR EARLY NEXT WEEK...HOWEVER WITH A VERY MOIST
AIRMASS IN PLACE AND PERIODIC SHORTWAVES EMBEDDED IN UPPER SOUTHWEST
FLOW...CHANCE POPS SHOULD BE SUFFICIENT TO COVER AT THIS TIME.

&&

.MARINE...

SURFACE HIGH PRESSURE OVER THE GREAT LAKES TONIGHT WILL SLIDE TOWARD
THE ATLANTIC COAST SATURDAY BUT REMAIN IN CONTROL OF THE WEATHER
OVER LAKE HURON AND LOWER MICHIGAN. THIS WILL PROVIDE FAVORABLE
MARINE CONDITIONS IN TERMS OF LIGHT WIND AND LOW WAVES SATURDAY INTO
SUNDAY...AND THE TEMPERATURE WILL RISE EACH DAY. THE POTENTIAL FOR
SHOWERS AND THUNDERSTORMS WILL THEN STEADILY INCREASE SUNDAY THROUGH
THE BEGINNING OF NEXT WEEK AS THE WARMER AND MORE HUMID AIR ARRIVES
IN THE GREAT LAKES.

&&

.AVIATION...ISSUED 118 PM EDT FRI MAY 22 2015

SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION THROUGH
TOMORROW. CLEAR SKIES AND LIGHT WINDS WILL BE EXPECTED AT ALL TAFS
THROUGH THIS PERIOD. ONLY MAJOR CONCERN WILL BE THE DEVELOPMENT OF A
LAKE BREEZE OFF OF LAKE HURON MOVING ONSHORE LATE FRIDAY AFTERNOON
AND EARLY EVENING. INTENSITY OF THIS BOUNDARY IS STILL UNCERTAIN
HOWEVER...THERE SHOULD BE A NOTABLE WIND SHIFT REGARDLESS OF HOW
STRONG THE BOUNDARY BECOMES.

FOR DTW...UNCERTAINTY REMAINS IN HOW FAR SOUTH THE LAKE BREEZE OFF
LAKE HURON WILL TRAVEL. FOR NOW...HAVE JUST INCLUDED A SLIGHT SHIFT
IN WIND IN THE LATE AFTERNOON HOURS...HOWEVER...WILL HAVE TO KEEP AN
EYE ON THIS AS THE LAKE BREEZE DEVELOPS.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...FROST ADVISORY FROM 2 AM TO 8 AM EDT SATURDAY FOR MIZ047>049-
     053>055-060>063-068>070.

LAKE HURON...NONE.

LAKE ST CLAIR...NONE.

MICHIGAN WATERS OF LAKE ERIE...NONE.

&&

$$

SHORT TERM...RK
LONG TERM....BT/DE
MARINE.......BT
AVIATION.....RK


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



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