Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 031917
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
317 PM EDT TUE MAY 3 2016

.DISCUSSION...

LATEST WATER VAPOR IMAGERY SHOWS HIGHLY AMPLIFIED UPPER LEVEL RIDGE
OVER THE ROCKIES OF NORTH AMERICA... WITH IMPRESSIVE UPPER LEVEL
LOW/CIRCULATION TRACKING THROUGH THROUGH WESTERN ONTARIO. THIS
SYSTEM WILL BE TENDING TO TAKE ON A NEGATIVE TILT AS IT DROPS SOUTH
THROUGH WESTERN/CENTRAL GREAT LAKES...WITH THE 500 MB COLD POOL OF
-28 C TRACKING THROUGH LAKE MICHIGAN...PER 12Z EURO. THIS IS
IMPORTANT...AS THE VARIOUS OTHER MODELS (GFS/NAM/REGIONAL GEM) HAVE
THE -25 TO -28 C COLD POOL TRACKING JUST WEST OF LAKE MICHIGAN.

LOW PRESSURE DEVELOPING ALONG THE FRONTAL BOUNDARY WILL TEND TO
STALL THE FRONT DURING THE DAY...WITH A GOOD DEFORMATION ZONE
SETTING UP...ALTHOUGH EXACT LOCATION OF LOW LEVEL CONVERGENCE
ZONE/CIRCULATION VARIES AMONGST 12Z GFS/NAM/REGIONAL GEM. BUT
AGAIN...IF ONE FAVORS THE FARTHER EAST SOLUTION OF THE EURO...AREAS
ALONG AND WEST OF U.S 23 STAND GOOD CHANCE TO BE EMBEDDED WITH THE
HEAVIER RAINFALL AXIS (IN EXCESS OF HALF AN INCH). PW VALUE WILL BE
RUNNING AROUND 0.75 INCHES...AND THERE DOES LOOK TO BE SOME
CONVECTIVE ELEMENTS/POSSIBLE THUNDERSTORMS WITH PRETTY GOOD MID
LEVEL LAPSE RATES (UP TO 7 C/KM FROM 700-500 MB). 12Z NAM SUGGEST
1000-850 MB CAPES UP TO 500 J/KG...BUT THAT IS LIKELY OVERDONE. IN
ADDITION...LOW LEVEL MOISTURE QUALITY IS NOT THAT GREAT WITH 850 MB
DEW PTS OF 3 C AND SURFACE DEW PTS ONLY IN THE 40S...LEADING TO
SOME UNCERTAINTY WITH AREAL COVERAGE OF ACTIVITY...AND BULK OF
ACTIVITY WILL PREDOMINATELY BE FOCUSED ALONG THE SHEAR/CONVERGENCE
AXIS DRAPED ACROSS THE WESTERN THIRD OF THE CWA.

THERE DOES LOOK TO BE SOME LOW LEVEL WARM ADVECTION OCCURRING OVER
THUMB REGION AND FAR EASTERN AREAS...WHERE TEMPERATURES WILL HAVE A
SHOT AT REACH OR EXCEED 60 DEGREES TOMORROW BEFORE SHOWERS/CONVECTION
PUSHES EAST.

FORTUNATELY...GOOD SOUTHWARD MOMENTUM SHOULD PUSH 500 MB LOW/COLD
CENTER OVER THE EASTERN TENNESSEE VALLEY THURSDAY MORNING
(ALLOWING SHOWERS TO TAPER OFF FROM NORTH TO SOUTH WEDNESDAY
EVENING ...WITH PRONOUNCED UPPER LEVEL RIDGING EXTENDING EASTERN
INTO THE GREAT LAKES REGION FOR END OF THE WORK WEEK...ALLOWING
FOR A WARMUP INTO FRIDAY WITH TEMPERATURES PUSHING TO 70 DEGREES
AS 850 MB TEMPS RISE INTO THE UPPER SINGLE NUMBERS BY DAY`S END.

12Z MODEL SUITE CONTINUES THE FASTER TREND FOR THE WAVE AND
ASSOCIATED FRONT FOR SATURDAY...NOW SUPPORTING A BETTER CHANCE OF
SHOWERS AND THUNDERSTORMS DURING THE DAY. MODELS HAVE BEEN
CONSISTENT IN AGGRESSIVELY EXPANDING HIGH PRESSURE INTO THE GREAT
LAKES IN THE WAKE OF THE FRONT. ASSUMING THIS SCENARIO PLAYS
OUT...SUNDAY WOULD BE DRY AND COOLER. RIDGING AT THE SURFACE AND
ALOFT WILL FAVOR DRY WEATHER INTO MONDAY...WITH HEIGHT FALLS AND
ASSOCIATED PRECIP CHANCES RETURNING BY TUESDAY.

&&

.MARINE...

A LIGHT SOUTHERLY WIND WILL EXIST THIS EVENING IN ADVANCE OF A COLD
FRONT. AN AREA OF LOW PRESSURE WILL DEVELOP OVER LOWER MI ALONG THIS
THIS COLD FRONT AS IT MOVES THROUGH ALL WATERWAYS LATE TONIGHT AND
WEDNESDAY. WINDS WILL BECOME NORTHERLY AND STRENGTHEN WITH THIS
FRONTAL PASSAGE BY WEDNESDAY NIGHT. STRONGEST WINDS WILL BE ACROSS
SOUTHERN SECTIONS OF LAKE HURON...WHERE A PERIOD OF WINDS UP TO 20
KNOTS APPEARS LIKELY. THE ONSHORE FLOW WILL LEAD TO A PERIOD OF
ELEVATED WAVE CONDITIONS ALONG THE THUMB WEDNESDAY NIGHT AND
THURSDAY. HIGH PRESSURE WILL THEN BRING TRANQUIL MARINE CONDITIONS
FOR THE LATE WEEK PERIOD.

&&

.HYDROLOGY...

THE NEXT SYSTEM WAS DIVING SOUTH AND WILL STRENGTHEN AS IT MOVES
OVER LOWER MI.  SHOULD BE STRONG FORCING ON THE NORTHWEST FLANK OF
THE SYSTEM SETTING UP A 9 TO 12 HOUR WINDOW THAT WILL FOCUS SOME
HEAVIER RAINFALL DURING THE DAY ON WEDNESDAY. STILL SOME UNCERTAINTY
ON THE PLACEMENT OF HEAVY RAINFALL AXIS...BUT AREAS AROUND LAN TO
MBS TO HTL LOOK MOST LIKELY TO GET UP TO AN INCH. AREAS SOUTH AND
EAST WILL HAVE A MORE SHOWERY PATTERN WITH SOME THUNDERSTORMS. THESE
MAY PRODUCE SOME HEAVIER RAINFALL BUT A BASIN AVERAGE SHOULD BE A
QUARTER TO A HALF INCH. ALL OF THIS PULLS AWAY AS THE SYSTEM MOVES
SOUTHEAST WEDNESDAY NIGHT WITH GENERALLY DRY WEATHER THURSDAY AND
FRIDAY.

&&

.AVIATION...ISSUED 1255 PM EDT TUE MAY 3 2016

THE REST OF THE AFTERNOON WILL BE HIGHLIGHTED WITH DIURNAL CU
ABOVE 5000 FEET AND LIGHT WEST WINDS. TONIGHT WILL HAVE INCREASING
CLOUDS FROM NORTH TO SOUTH AHEAD OF THE NEXT SYSTEM AS THEY LOWER
TO AROUND 3000-5000 FEET. ALL INDICATIONS OF THE NEXT SYSTEM
WRAPPING UP OVER SOUTH CENTRAL LOWER MICHIGAN. THIS WILL KEEP THE
NORTHERN TAF SITES OF FNT AND MBS IN LOWER CEILINGS AND
VISIBILITIES WITH A STEADY RAIN ON WEDNESDAY MORNING. EXPECT MVFR
TO NEAR IFR CEILINGS AND VISIBILITIES FOR THESE TWO SITES. A MORE
OPTIMISTIC FORECAST IS LIKELY FOR THE MORNING FOR THE METRO
DETROIT TAFS AS IT WILL TAKE MORE TIME FOR THE DEEPER AND LOW
LEVEL MOISTURE TO MOVE OVER THE AREA.

FOR DTW...JUST HIGHER BASED...ABOVE 5000 FEET...BROKEN CEILING
DIURNAL CUMULUS FOR THE REST OF THE AFTERNOON. THE FIRST HALF OF
THE NIGHT SHOULD HAVE JUST SCATTERED CLOUDS...BEFORE SOME
ALTOCUMULUS AROUND 8000 FEET MOVES IN FROM 07Z TO 14Z.

//DTW THRESHOLD PROBABILITIES...

* NONE

&&

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

$$

DISCUSSION...SF/DT
MARINE.......RBP
HYDROLOGY....RBP
AVIATION.....RBP


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


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