Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 311743
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
143 PM EDT MON AUG 31 2015


.AVIATION...

REMNANTS OF MORNING STRATUS DECK OVER SOUTH-CENTRAL LOWER MICHIGAN
WILL MIX OUT BY OR JUST SHORTLY AFTER 18Z. UPPER LEVEL HIGH PRESSURE
WILL THEN PROVIDE QUIET WEATHER AND WESTERLY WINDS UNDER 10 KNOTS
TODAY. CLEAR SKIES AND LIGHT WINDS OVERNIGHT WILL AGAIN BRING
POTENTIAL FOR FOG TO FORM. COVERAGE IS A LITTLE MORE UNCERTAIN TODAY
AS SOME OF THE MOISTURE SHOULD BE MIXING OUT OF THE AREA...AND NO
PRECIPITATION IS EXPECTED TODAY. WILL CONTINUE TO LEAN TAFS TOWARDS
MVFR REDUCTIONS AROUND 08-09Z...WITH SOME IFR FILLING IN JUST BEFORE
SUNRISE AND LASTING FOR A FEW HOURS BEFORE FOG MIXES OUT ONCE AGAIN
IN THE LATE MORNING.

//DTW THRESHOLD PROBABILITIES...

* LOW FOR VISIBILITY BELOW 1/2 MILE OR CEILINGS BELOW 200 FEET AFTER
  08Z TONIGHT.

&&

.PREV DISCUSSION...ISSUED 337 AM EDT MON AUG 31 2015

SHORT TERM...TODAY AND TONIGHT

SOLID LATE SUMMER UPPER RIDGE AMPLIFICATION /590 DM HEIGHTS AT 500 MB/
WILL STEADILY TAKE HOLD ACROSS SE MICHIGAN OVER THE NEXT 24 HOURS.
LOW LEVEL RIDGING ELONGATED ACROSS THE APPALACHIANS WILL ENSURE
LIGHT SOUTHWEST FLOW EXISTS...TUCKED BENEATH STABLE MID LEVEL
ANTICYCLONIC FLOW AND AN ACCOMPANYING MINIMUM IN THETA-E.  LACK OF
FLOW AND RESIDUAL MOIST NEAR SURFACE CONDITIONS YIELDING A FAVORABLE
ENVIRONMENT FOR FOG DEVELOPMENT EARLY THIS MORNING.  DENSE FOG
ADVISORY ALREADY IN PLACE TO HIGHLIGHT THE POTENTIAL FOR AREAS OF
DENSE FOG AND ACCOMPANYING RAPID REDUCTION IN VISIBILITY THROUGH THE
MORNING COMMUTE.  WILL CONTINUE TO MONITOR TRENDS AND ADJUST
HEADLINE NEEDS ACCORDINGLY MOVING FORWARD INTO THE MID MORNING
PERIOD.

OTHERWISE...CONDITIONS TODAY CHARACTERIZED BY A NOTEWORTHY UPWARD
TREND IN TEMPERATURES RELATIVE TO RECENT DAYS...WITH THE EMERGING
HIGH DEGREE OF SUNSHINE ONCE THE FOG LIFTS AND A GENERAL INCREASE IN
MEAN THICKNESSES SUPPORTING HIGHS OF MIDDLE AND UPPER 80S.  POCKET
OF COOLER MID LEVEL TEMPERATURES ASSOCIATED WITH A DISORGANIZED AND
WEAK DISTURBANCE MEANDERING ACROSS THE OHIO VALLEY WILL REMAIN SOUTH
OF THE LOCAL AREA THROUGH TONIGHT.  GENERAL SUBSIDENCE THROUGH THE
COLUMN WILL TRANSLATE INTO A DRY PERIOD.  ENVIRONMENT WILL REMAIN
FAVORABLE FOR SOME DEGREE OF FOG DEVELOPMENT AGAIN TONIGHT...LIKELY
OF LESS COVERAGE/MAGNITUDE GIVEN A FULL DAY SUNSHINE TO MIX OUT THE
BOUNDARY LAYER.  THEREFORE WILL SIMPLY INTRODUCE A PATCHY MENTION
FOR THE EARLY MORNING PERIOD.

LONG TERM...

AN EXTENDED STRETCH OF WARM WEATHER AS 1000-500 MB THICKNESSES LOOK
TO REMAIN ABOVE 570 DAM THROUGH THE ENTIRE FORECAST PERIOD.

STRONG UPPER LEVEL RIDGE (588+ DAM AT 500 MB) LOOKS TO BE IN PLACE
OVER LOWER MICHIGAN ON TUESDAY...FOR THE MOST PART.
HOWEVER...CLOSED CIRCULATION/CONSOLIDATED UPPER LEVEL PV OVER THE
WESTERN OHIO VALLEY WILL BE TRACKING OFF TO THE EAST-NORTHEAST. THIS
WEAKNESS/MOISTURE ADVECTION CROSSING JUST PAST THE SOUTHERN MICHIGAN
BORDER COULD PROVE SUFFICIENT TO GENERATE ISOLATED THUNDERSTORM
ACTIVITY...AS INSTABILITY/CAPE LOOKS TO BE LOW TO MODERATE.
WIND FIELDS WILL BE VERY WEAK HOWEVER...AS 500 MB WINDS LOOK TO BE
10 KNOTS OR LESS. 00Z ILX SOUNDING OVER CENTRAL ILLINOIS STILL
SHOWING A GOOD DEAL OF MOISTURE...WITH 15 C DEW PT AT 850 MB AND 6 C
DEW PT AT 700 MB. 00Z NAM INITIALIZATION AT THIS LOCATION IS GROSSLY
UNDERDONE WITH THE MOISTURE. EVEN SO...NAM SOUNDINGS ON TUESDAY
SHOWING NO CAP TO SPEAK OFF NEAR THE OHIO BORDER...AND HAVE
INTRODUCED SLIGHT CHANCE POPS ACROSS SOUTHERN FOUR COUNTIES FOR
AFTERNOON HOURS. EXPECTING MAXES IN THE MID TO UPPER 80S BASED ON
850 MB TEMPS OF 17 TO 18 C.

THE 500 MB LOW IS FORECASTED TO PUSH EAST ON WEDNESDAY...WITH SLIGHT
REINFORCING UPPER LEVEL RIDGE ATTEMPTING TO BUILD BACK ACROSS LOWER
MICHIGAN. HOWEVER...THERE IS A SHORTWAVE PROGGED TO TRACK THROUGH
THE STRAIGHTS/NORTHERN LAKE HURON...WHICH WILL DRAG A WEAK COLD
FRONT INTO THE AREA...WHICH COULD PROVE SUFFICIENT TO GENERATE
AFTERNOON CONVECTION (MAINTAINED SLIGHT CHANCE) WITH 1000-850 MB
CAPES IN THE 1000-1500 J/KG RANGE. HOWEVER...THE 00Z GFS SHOWS 700
MB RISING TO 10 C...WHICH WOULD LIKELY CAP ACTIVITY...WHILE 00Z EURO
SHOWS SLIGHT COOLING DOWN TO AROUND 8 C BY 00Z THURSDAY. 850 MB
TEMPS OF 18 TO 20 C SUGGEST HIGHS NEAR 90 DEGREES.

MODEST HEIGHT FALLS/COOLING (500 MB TEMP OF -10 C) ON THURSDAY WILL
PROMOTE MODERATE INSTABILITY (1000-850 MB CAPE OF 1500+ J/KG PER
EURO) AND SLIGHT CHANCE POPS ONCE AGAIN...ESPECIALLY WESTERN AREAS
AS DRIER AIR (850-700 MB THETA-E TROUGHING) WORKS SOUTH THROUGH LAKE
HURON.

MARINE...

QUIET MARINE WEATHER WILL PERSIST OVER THE CENTRAL GREAT LAKES
THROUGH MUCH OF THE UPCOMING WEEK. A STRONG UPPER LEVEL RIDGE AND
GENERALLY A WEAK PRESSURE GRADIENT AT THE SURFACE WILL MAINTAIN
LIGHT WINDS AND LOW WAVES. HOWEVER...THERE WILL BE A SLIGHT CHANCE
OF THUNDERSTORMS DURING MOST AFTERNOONS.

&&

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

$$

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


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AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).


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