Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 160731
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
331 AM EDT THU APR 16 2015

.SHORT TERM... TODAY AND TONIGHT

ELONGATING MID LEVEL TROUGH CARRYING SEVERAL INDIVIDUAL SHORTWAVE
FILAMENTS WILL PROGRESS ACROSS SE MICHIGAN OVER THE NEXT 24 HOURS.
DRY EASTERLY FLOW HOLDING FIRM LOCALLY EARLY THIS MORNING...A NARROW
RIBBON OF HIGHER MOISTURE CONTENT RAPIDLY ADVECTING NORTHWARD WILL
SETTLE INTO WESTERN LOWER OVER THE COURSE OF THE MORNING.   THIS
PROCESS WILL PROVIDE A THICKER CANOPY OF MID CLOUD COVER THIS
MORNING...BUT RAINFALL CHANCES WILL REMAIN SLIM GIVEN THE LACK OF
AVAILABLE MOISTURE OR TANGIBLE FORCING.

PASSAGE OF THE MAIN VORTICITY CENTER ANCHORING THE MID LEVEL TROUGH
WILL PROVIDE A MORE FAVORABLE BACKGROUND FOR SOME DEGREE OF SHOWER
DEVELOPMENT THIS AFTERNOON AND EVENING.  ARRAY OF 00Z MODEL GUIDANCE
PROVIDING A MIXED SIGNAL ON POSSIBLE COVERAGE...HI RES SOLUTIONS
CARRYING A MORE MUTED RESPONSE NOW RELATIVE TO THE GFS/ECMWF.  THIS
TREND LIKELY OWING TO THE OVERALL RELATIVELY WEAK AND DISORGANIZED
FORCING FIELD.  AFOREMENTIONED HIGHER MOISTURE PLUME EXISTING JUST
UPSTREAM WILL ACCOMPANY THE LOWER HEIGHTS THROUGH DURING THIS
TIME...WARRANTING AT LEAST CHANCE POPS ACCOUNTING FOR SOME MINOR
DIURNAL ASSISTANCE TOWARD ANY SHOWER EXPANSION.  PERSISTENT
SOUTHEAST FLOW BENEATH THE EXTENSIVE CLOUD COVER WILL CAP THE
OVERALL DIURNAL TEMPERATURE RESPONSE...REGARDLESS OF THE SHOWER
COVERAGE.  HIGHS UPPER 50S TO LOWER 60S.

MID LEVEL TROUGH AXIS PIVOTS THROUGH TONIGHT.  EXTENSIVE LOW LEVEL
MOISTURE TIED TO THE THERMAL TROUGHING WILL KEEP SKIES CLOUDY WELL
INTO THE EARLY MORNING PERIOD.  A FEW LIGHT SHOWERS/SPRINKLES REMAIN
PLAUSIBLE THROUGH THE FIRST HALF OF THE NIGHT AS THIS PROCESS
UNFOLDS.  LOWS TONIGHT LOWER AND MIDDLE 40S.

&&

.LONG TERM...

UPPER LEVEL NORTHWEST FLOW IN PLACE ON FRIDAY WITH NEAR STEADY 500
MB HEIGHTS. LOW LEVEL WESTERLY FLOW SHOULD ALLOW FOR SUFFICIENT
DRYING TO SUPPORT MOSTLY SUNNY SKIES...AS 1000-500 MB MEAN RH DROPS
BELOW 50 PERCENT. CONFIDENCE REMAINS HIGH IN MAXES REACHING AROUND
70 DEGREES FOR MANY LOCATIONS WITH 850 MB TEMPS OF 7.5 TO 9 C
ADVERTISED AHEAD OF A WEAK COLD FRONT...WHICH WILL ONLY HELP ASSURE
MIXING DEPTHS EXTEND BEYOND 850 MB...AND THE DETROIT AREA AND POINTS
SOUTH WILL LIKELY SEE MAXES IN THE LOWER 70S.

STRONG UPPER WAVE TRACKING THROUGH ONTARIO ON FRIDAY AND INTO
NORTHERN NEW ENGLAND ON SATURDAY. THIS REMAINS FAR ENOUGH NORTH TO
SUPPORT JUST A GLANCING BLOW OF COOLER AIR TO SOUTHEAST
MICHIGAN...AS THE COLD FRONT DROPPING SOUTH THROUGH THE CENTRAL
GREAT LAKES MORE OR LESS WASHES OUT WITH 500 MB HEIGHTS REBOUNDING
ON SATURDAY. INCREASING NORTHEAST WINDS OFF LAKE HURON DURING
SATURDAY WILL BE A SIGNIFICANT FACTOR LATE IN THE DAY...BUT NOT
BEFORE TEMPERATURES MAKE ANOTHER RUN TOWARD 70 DEGREES TOWARD THE
OHIO BORDER...AS 850 MB TEMPS PROGGED TO HOVER AROUND 8 C THROUGH
18Z SATURDAY PER 00Z EURO/GFS.

STILL LOOKING AT MERGER/PHASING OF THE NORTHERN AND SOUTHERN STREAMS
OVER THE CENTRAL CONUS DURING THE SECOND HALF OF THE WEEKEND...AND
RAIN APPEARS LIKELY SUNDAY AND SUNDAY NIGHT AS LOW LEVEL JET RAMPS
UP (50+ KNOTS)...ALLOWING FOR 850 MB DEW PTS RISING TO AROUND 10 C
(BLEND OF GFS/EURO). ADDED A THUNDER MENTION WITH THE GOOD
DYNAMICS...AS SFC-850 MB LIS ALSO LOOK TO BECOME SLIGHTLY NEGATIVE.

&&

.MARINE...

SOUTHEAST WINDS TODAY WILL REMAIN LIGHT...UNDER 20 KNOTS AS WEAK LOW
PRESSURE MOVES INTO SOUTHERN LOWER MICHIGAN LATER TODAY. WEAK WIND
FIELD WILL PERSIST ON FRIDAY...AHEAD OF A COLD FRONT WHICH WILL
SWING THROUGH THE CENTRAL GREAT LAKES FRIDAY NIGHT. THE COLD PUSH
BEHIND THE FRONT LOOKS VERY WEAK...AND THUS WINDS ARE EXPECTED TO
REMAIN GENERALLY UNDER 20 KNOTS. THE STRONGEST WINDS MAY ACTUALLY
OCCURS SATURDAY AFTERNOON OVER SAGINAW BAY AS THE LAND/LAKE
DIFFERENTIAL HEATING/TEMPERATURE GRADIENT RAMPS UP...AND MARINE
LAYER LIKELY SURGES INLAND LATE IN THE DAY. LOSS OF DAYTIME HEATING
AND SURFACE RIDGE IN PLACE WILL QUICKLY ALLOW FOR RETURN TO THE
LIGHT WINDS SATURDAY EVENING/NIGHT.

&&

.AVIATION...ISSUED 1152 PM EDT WED APR 15 2015

VERY DRY LOW LEVEL AIR ASSOCIATED WITH HIGH PRESSURE DEPARTING TO
THE EAST WILL KEEP CLEAR SKIES BELOW 10K FEET AT THE TERMINALS
THROUGH DAYBREAK. AN INFLUX OF MOISTURE WILL ARRIVE FROM THE
SOUTHWEST THIS MORNING AND IS ASSOCIATED WITH THE PASSAGE OF A WEAK
UPPER LEVEL DISTURBANCE LIFTING UP FROM THE OH/MS VALLEY. THIS WILL
LEAD TO A STEADY DECREASE IN CEILINGS HEIGHTS DURING THE COURSE OF
THE DAY ON THURS AND A CHANCE OF LIGHT RAIN IN THE AFTERNOON.

FOR DTW...THE 00Z MODEL GUIDANCE WITH SOME SUPPORT OF UPSTREAM
OBSERVATIONS SUGGEST CEILINGS WILL DROP TO 5K FT LATE IN THE
MORNING.

//DTW THRESHOLD PROBABILITIES...

* HIGH IN CEILINGS DROPPING AT OR BELOW 5000 FT AFTER 14Z THURSDAY.

&&

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

$$

SHORT TERM...MR
LONG TERM....SF
MARINE.......SF
AVIATION.....SC


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



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