Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 030423
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1223 AM EDT TUE MAY 3 2016

.AVIATION...

PERSISTENT UPPER RIDGING OVER EASTERN NORTH AMERICA WILL MAINTAIN A
RATHER SLUGGISH TREND TO DRY AIR ADVECTION AND EROSION OF
STRATUS/STRATOCU/ALTOSTRATUS. THERE HAS BEEN SLOW SOUTHERN MOVEMENT
TO THE EDGE OF THE CLOUD DECK THE PAST FEW HOURS...BUT SUSPECT THAT
SKC/SCT CIRRUS WILL DEVELOP EITHER BY 6Z OR AN HOUR OR TWO AFTER AT
THE START OF THE PERIOD. A WEAK PRESSURE GRADIENT HAS ALREADY LED TO
A VARIABLE WIND FIELD IN MANY AREAS...SHALLOW FOG WILL ALSO BE A
POSSIBILITY FOR MANY AREAS LATER TONIGHT. THE PERSISTENT TROUGH AND
HIGHER AMBIENT MOISTURE WILL LEAD TO CUMULUS DEVELOPMENT AT 4000-
5000 KFT AGL DURING THE LATE MORNING AND EARLY AFTERNOON.

//DTW THRESHOLD PROBABILITIES...

* HIGH CONFIDENCE ABOVE 5000 FT AGL CIGS AT THE START OF THE PERIOD.
  LOW CONFIDENCE FOR PERIOD OF 5000 FOOT CEILINGS TOMORROW AFTERNOON
  (BKN CIGS ABOVE 5000 FT AGL).

&&

.PREV DISCUSSION...ISSUED 343 PM EDT MON MAY 2 2016

DISCUSSION...

SURFACE HIGH PRESSURE CENTERED OVER THE NORTHERN GREAT LAKES WILL
CONTINUE TO EXPAND INTO SOUTHEAST MICHIGAN TODAY. SATELLITE IMAGERY
HAS BEEN SHOWING A GRADUAL EROSION OF STRATUS TODAY AS THIS OCCURS
AND AS DRIER AIR SLOWLY FILTERS INTO THE AREA. BEHIND THE
STRATUS...DIURNAL FLARE-UP OF CU OCCURRED AS DAYTIME HEATING WORKS
WITH MOISTURE TRAPPED UNDER AN INVERSION NEAR 6000 FEET. CU SHOULD
DISSIPATE WITH LOSS OF HEATING THIS EVENING...ALLOWING SKIES TO
CLEAR FOR THE NORTHERN PORTION OF THE FORECAST AREA. FURTHER
SOUTH...AN UPPER WAVE WILL SLIDE EAST FROM THE CENTRAL PLAINS AND
INTO THE OHIO VALLEY. THIS DOES NOT LOOK TO BE CAPABLE OF PRODUCING
ANY RAINFALL FOR THE AREA...BUT SHOULD SPREAD ADDITIONAL HIGH AND
MID LEVEL CLOUDS ACROSS SOUTHERN LOWER MICHIGAN. MOST OF THIS
MOISTURE LOOKS TO BE POSITIONED SOUTH OF THE M-59 CORRIDOR. FROST
WILL BE POSSIBLE TONIGHT NORTH OF THE M-59 CORRIDOR WHERE LESS CLOUD
COVER AND LIGHT WINDS WILL PROMOTE BETTER RADIATIONAL COOLING
CONDITIONS AND ALLOW TEMPERATURES TO FALL INTO THE MID 30S. NO
ADVISORY IS PLANNED AS THE GROWING SEASON HAS ONLY BEEN SUFFICIENTLY
LONG ENOUGH ALONG/SOUTH OF THE I-69 CORRIDOR...WHERE HIGH CLOUDS MAY
BRUSH THE AREA FOR THE FIRST PART OF THE NIGHT. OTHER CONCERN WILL
BE THE FORMATION OF PATCHY SHALLOW FOG TONIGHT ACROSS THE ENTIRE
AREA AS GROUND REMAINS SATURATED FROM RAINFALL LAST NIGHT.

STRONG UPPER WAVE NOW JUST WEST OF HUDSON BAY WILL DROP INTO THE
NORTHERN AND CENTRAL GREAT LAKES TUESDAY INTO WEDNESDAY. SURFACE
TROUGH AND COLD FRONT ASSOCIATED WITH THE SYSTEM LOOK TO PROGRESS
THROUGH THE U.P. OF MICHIGAN TUESDAY. APPROACH OF THESE FEATURES
WILL DRAW WARMER AIR UP INTO LOWER MICHIGAN TUESDAY...ALTHOUGH
THERMAL RIDGE AXIS WILL REMAIN TO OUR NORTH AND WEST DURING THE DAY.
THERMAL ADVECTION AND A GOOD AMOUNT OF SUN SHOULD BOOST TEMPERATURES
INTO THE 60S. DAYTIME HEATING AND EROSION OF THE INVERSION/CAP AS
THE UPPER TROUGH/COLD POOL STARTS TO DROP INTO MICHIGAN WILL PROMOTE
DESTABILIZATION THROUGH THE DAY. MODEL FORECAST SOUNDINGS CONTINUE
TO LOOK TOO DRY TO SUPPORT ANY SHOWER/TSTORM MENTION HOWEVER. COLD
FRONT WILL DROP THROUGH SOUTHEAST MICHIGAN TUESDAY NIGHT AND EARLY
WEDNESDAY. MOISTURE POOLING AHEAD OF THE FRONTAL BOUNDARY COMBINED
WITH STEEPENING LAPSE RATES (ESPECIALLY AT THE MID-LEVELS) WILL
SUPPORT A GOOD COVERAGE OF SHOWERS AND EVEN THUNDERSTORMS...AND POPS
REMAIN AT HIGH LIKELY. SHOWERS WILL CONTINUE BEHIND THE FRONT ON
WEDNESDAY AS THE LOW AND COLD POOL REMAIN OVERHEAD. WEDNESDAY SHOULD
BE A GRUNGY DAY WITH SOLID LOW CLOUDS...NUMEROUS RAIN SHOWERS...AND
HIGH ONLY IN THE 50S (MAINLY DUE TO MILD OVERNIGHT TEMPS).

HIGHLY AMPLIFIED AND PROGRESSIVE SPLIT FLOW PATTERN ACROSS THE CONUS
THROUGH THE REMAINDER OF THE FORECAST. UPPER LOW DRIFTS AWAY
THURSDAY WITH A SLOW CLEARING TREND EXPECTED. EXPANSIVE CENTRAL
CONUS RIDGE BUILDS IN FRIDAY/SATURDAY LEADING TO A SOLID WARMING
TREND...SOUTHWESTERLY FLOW AHEAD OF A NORTHERN STREAM WAVE POSSIBLY
PROPELLING HIGHS INTO THE 70S BY SATURDAY. TIMING ON AFOREMENTIONED
WAVE/SURFACE FRONT WILL TARGET SATURDAY NIGHT FOR ASSOCIATED
SHOWER/TSTORM CHANCES...NOT AS WARM FOR SUNDAY IN THE WAKE OF THE
FRONTAL PASSAGE.

MARINE...

A LIGHT AND VARIABLE WIND WILL EXIST TONIGHT AND TUESDAY
IN ADVANCE OF A COLD FRONT.  THIS COLD FRONT SHIFTS THROUGH ALL
WATERWAYS LATE TUESDAY NIGHT THROUGH EARLY WEDNESDAY.  WINDS WILL
BECOME NORTHWESTERLY AND STRENGTHEN WITH THIS FRONTAL PASSAGE ON
WEDNESDAY.  STRONGEST WINDS ACROSS NORTHERN AND CENTRAL SECTIONS OF
LAKE HURON...WHERE A PERIOD OF WINDS AROUND 25 KNOTS APPEARS LIKELY.

HYDROLOGY...

THE NEXT ROUND OF RAIN IS ON TRACK FOR LATE TUESDAY NIGHT THROUGH
THE DAY ON WEDNESDAY AS A DEEPENING STORM SYSTEM PASSES THROUGH
LOWER MICHIGAN. AT THIS TIME...RAINFALL TOTALS ARE EXPECTED TO BE A
QUARTER TO HALF AN INCH BY THE TIME THE RAIN TAPERS OFF WEDNESDAY
EVENING.

&&

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

$$

AVIATION.....MR
DISCUSSION...HLO/DT
MARINE.......SF
HYDROLOGY....SF

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



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