Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 010752
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
352 AM EDT SUN MAY 1 2016

.DISCUSSION...

MOISTURE LADEN ENVIRONMENT FIRMLY ENCOMPASSING SE MICHIGAN EARLY
THIS MORNING...THE REMNANT PROFILE LEFT IN THE WAKE OF A PERIOD OF
STRONG MID LEVEL FORCING/WAA AND CORRESPONDING REGION OF WIDESPREAD
RAINFALL.  TRANSITION PERIOD THROUGH THE LATTER HALF OF THE
MORNING...A PROGRESSIVE EXIT OF BOTH THE DEEPER LAYER MOISTURE AND
MID LEVEL FORCING WILL CONTINUE TO PROMOTE THE RAPID REDUCTION IN
BOTH COVERAGE AND INTENSITY OF RAINFALL. RESIDUAL MOIST LOWEST
3000 FT TUCKED BENEATH THE INBOUND DRY SLOT WILL CONTINUE TO
SUPPORT ADDITIONAL POCKETS OF LIGHT SHOWERS/DRIZZLE THROUGH THE
FIRST HALF OF THE DAY. THE EXISTING LOW LEVEL NORTHEAST GRADIENT
COMBINED WITH THE EXTENSIVE CLOUD COVER WILL AGAIN RESULT IN A
MUTED DIURNAL TEMPERATURE RESPONSE. SLOWER EVACUATION OF
PRECIPITATION WITH NORTHWARD EXTENT WILL LIKELY ESTABLISH A LARGER
TEMPERATURE GRADIENT FROM SOUTH TO NORTH. OUTGOING FORECAST CALLS
FOR HIGHS RANGING FROM NEAR 60 ALONG THE OHIO BORDER TO UPPER 40S
ACROSS THE NORTHERN TRI- CITIES/THUMB.

ATTENTION FOR TONIGHT TURNS TO THE MID LEVEL CIRCULATION CURRENTLY
PIVOTING ACROSS THE CENTRAL PLAINS.  THIS SYSTEM EXPECTED TO EJECT
EAST-NORTHEAST OVER THE NEXT 24 HOURS...THE MAIN VORTICITY AXIS
SWEEPING ACROSS THE NORTHERN OHIO VALLEY/LOWER MICHIGAN BY TONIGHT.
SOLID INCREASE IN MID LEVEL FORCING TIED TO THIS FEATURE...A PERIOD
OF STRONG DCVA AND DEFORMATION AUGMENTED BY FAVORABLE LEFT EXIT
REGION UPPER JET DYNAMICS.  THIS ALL POINTS TOWARD SEEING AN
AGGRESSIVE INCREASE IN RAINFALL COVERAGE AGAIN TONIGHT. POSITIONING/
TRACK OF THIS FORCING WILL LIKELY LEAVE A MORE DEFINED NORTHERN
EXTENT TO THIS PRECIPITATION SWATH.  CURRENT EXPECTATION BEING
ROUGHLY ALONG THE I-69 CORRIDOR...WITH PRECIPITATION CHANCES
CONSIDERABLY LOWER ACROSS THE TRI-CITIES/THUMB.  GIVEN THE DEGREE OF
FORCING AND EXISTING MOISTURE QUALITY...LOOKING AT A MORE SIZABLE
RESPONSE IN TERMS OF RAINFALL AMOUNTS...UPWARDS OF ONE HALF TO THREE
QUARTERS OF INCH /HIGHEST SOUTH OF I-96/.

TRAILING BROADER NORTHERN STREAM TROUGH WILL FILL IN BEHIND THIS
SYSTEM FOR MONDAY.  RESIDUAL LOW LEVEL THERMAL TROUGHING UNDER
NORTHEAST LOW LEVEL FLOW SUGGESTS THE CLEARING TREND WILL BE SLOW
PROCESS...ONE THAT LIKELY TAKES THE DURATION OF THE DIURNAL CYCLE
FOR SOUTHERN LOCATIONS.  A NEUTRAL TO SLIGHTLY COOLER TEMPERATURE
PROFILE ONCE AGAIN WILL TRANSLATE INTO BELOW NORMAL HIGHS...BUT MORE
UNIFORMLY IN THE VICINITY OF 60 DEGREES /OUTSIDE OF THE TYPICALLY
COOLER NEARSHORE LOCALES GIVEN THE ONSHORE FLOW/. YET ANOTHER WAVE
LIFTING OUT OF THE PLAINS WILL LARGELY PASS BY TO THE SOUTH MONDAY
NIGHT/EARLY TUESDAY. A PERIOD OF MINOR ASCENT WITH THE ELONGATED
TROUGH MAY RESULT IN RENEWED CLOUDINESS...BUT PRECIPITATION
CHANCES CURRENTLY APPEAR MINIMAL WITH THE GREATER FORCING FOCUSED
TO THE SOUTH.

NOTABLY WARMER ON TUESDAY AS THE LOW LEVEL GRADIENT FLIPS TO
WEST/SOUTHWEST IN ADVANCE OF STRONGER WAVE AND ATTENDANT COLD FRONT
DIGGING TOWARD THE GREAT LAKES. A SEASONABLE LOOKING EARLY MAY
DAY...WITH READINGS REACHING INTO THE MIDDLE 60S.  LATEST TRENDS IN
MODEL GUIDANCE BRING THE LEAD EDGE OF THE MAIN HEIGHT FALLS
AND FRONTAL STRUCTURE INTO SE MICHIGAN LATE TUESDAY NIGHT
INTO WEDNESDAY. STRONG SIGNAL OF LINEAR FORCING WITH THESE
FEATURES SUGGESTS A SOLID WINDOW FOR SHOWER DEVELOPMENT DURING
THIS TIME.  ECMWF/GFS BOTH INDICATE THE PARENT MID LEVEL
CIRCULATION WILL CLOSE OFF AS IT ENTERS THE GREAT LAKES...THE
ASSOCIATED EXPANSIVE CYCLONICFLOW REMAINING PREVALENT OVER THE
REGION THROUGH AT LEAST THURSDAY. TRANSLATION WILL BE A SOMEWHAT
UNSETTLED PERIOD...COOLISH BYEARLY MAY STANDARDS WITH AT LEAST A
LOW END CHANCE FOR SHOWERS.

&&

.MARINE...

SMALL CRAFT ADVISORY FOR THE NEARSHORE ZONES OF LAKE HURON REMAINS
IN EFFECT AS FRESH ONSHORE FLOW BUILDS BUILDS WAVES TO HAZARDOUS
LEVELS THROUGH TODAY. A WEAK PRESSURE GRADIENT WILL THEN FAVOR LIGHT
TO MODERATE BREEZE ACROSS THE WATERS THROUGH MIDWEEK.

&&

.HYDROLOGY...

A COMPACT AND FAST-MOVING SYSTEM WILL MOVE THROUGH THE AREA TONIGHT.
A QUICK QUARTER OF AN INCH OF RAIN WILL BE POSSIBLE MAINLY SOUTH OF
THE M59 CORRIDOR WITH ONE HALF TO THREE QUARTERS OF AN INCH POSSIBLE
SOUTH OF 8 MILE ROAD. THE BULK OF RAINFALL IS FORECAST TO OCCUR
BETWEEN MIDNIGHT AND 5AM LOCAL TIME.

&&

.AVIATION...ISSUED 1229 AM EDT SUN MAY 1 2016

LATEST REGIONAL MOSAIC TRENDS SUGGESTS THE HEIGHT OF THE RAINFALL
EVENT IS NOW AT PRESS TIME. THE COMBINATION OF THE LOW LEVEL JET
AXIS VEERING ACROSS THE STATE AND RIGHT ENTRANCE REGION DYNAMICS
PULLING EASTWARD OUT OF ONTARIO WILL CAUSE THE MAIN SWATH OF RAIN TO
LIFT NORTH AND EAST OUT OF SOUTHEASTERN MICHIGAN WITH TIME. WILL SEE
A TRANSITION TO DRIZZLE WITH THE DRY SLOT LIFTING INTO THE STATE.
THERE IS NOW INCREASING CONCERNS FOR LIFR TO POSSIBLY EVEN VLIFR
CEILING HEIGHTS AS A POSSIBILITY. CONFIDENCE IS LOW ATTM ON CEILING
HEIGHTS BELOW 500 FT AGL. THE BAND WILL EVENTUALLY LIFT NORTH OF
SAGINAW BAY DURING THE MID MORNING HOURS. LACK OF ANY POSITIVE
SURFACE PRESSURE TENDENCIES WILL LIMIT ADVECTIONS ON SUNDAY. THIS
WILL KEEP A MVFR CEILING IN PLACE OVER THE STATE. TIMING FOR THE
ONSET OF THE NEXT RAINFALL EVENT IS EXPECTED TO BE DURING THE MID
EVENING HOURS SUNDAY.

FOR DTW...WATCHING FOR THE POSSIBILITY OF VLIFR CONDITIONS IN LOW
CIG HEIGHTS. ATTM...CONFDIENCE REMAINS LOW. BACK EDGE OF THE
PRECIPITATION SHIELD IS NOW WORKING TOWARDS DETROIT. EXPECTING A
TRANSITION TO DRIZZLE WITH THE DRY SLOT LIFTING OVERHEAD. MVFR CIGS
TO PERSIST ALL OF SUNDAY WITH RAINFALL LIFTING BACK TOWARDS DETROIT
BY/AROUND 05Z SUNDAY EVENING.

//DTW THRESHOLD PROBABILITIES...

* HIGH FOR CIGS BELOW 5000 FT AGL THROUGHOUT THE ENTIRE TAF
  FORECAST PERIOD.

* LOW FOR A CEILIGN HEIGHT OF AT/LESS THAN 200 FT AGL.

* VERY LOW FOR A THUNDERSTORM TO IMPACT DTW.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LHZ421-441-442.

LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
&&

$$

DISCUSSION...MR
MARINE.......JVC
HYDROLOGY....JVC
AVIATION.....JVC

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



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