Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 281117
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
717 AM EDT FRI AUG 28 2015

.AVIATION...

QUIET PERIOD IN STORE AS PATCHY RADIATION FOG AND ISOLATED STRATUS
BURN OFF QUICKLY THIS MORNING GIVING WAY TO CLEAR SKIES BELOW 15KFT.
LIGHT SOUTHERLY WINDS WILL ACCOMPANY A DEVELOPING HIGH BASED CU
FIELD THAT IS FORECAST TO ACHIEVE BKN COVERAGE BY THIS AFTN.
GRADUALLY LOWERING CEILING WILL SIGNAL THE APPROACH OF A WAVE
PASSING OVER THE CENTRAL GREAT LAKES...BUT APPEARS TO BE OF LITTLE
CONSEQUENCE AT THIS TIME AS BEST MOISTURE REMAINS FAR TO THE NORTH
AND WEST. AS SUCH, UPON DISSIPATION OF DIURNAL CU, EXPECT CLEAR
SKIES BELOW 10KFT WILL BE THE RULE THROUGH TONIGHT AS WELL. LONE
EXCEPTION IS MBS WHICH MAY SEE A PERIOD OF LOWER VFR AND
POSSIBLY A STRAY SHOWER TOWARD SUNRISE SATURDAY.

//DTW THRESHOLD PROBABILITIES...

* MEDIUM IN CIGS AOB 5KFT 20-01Z TODAY.

&&

.PREV DISCUSSION...ISSUED 308 AM EDT FRI AUG 28 2015

SHORT TERM...TODAY AND TONIGHT

LOW AMPLITUDE SHORTWAVE RIDGING WILL DOMINATE THROUGH TODAY AS
SURFACE HIGH PRESSURE SLIDES EAST. DEVELOPING RETURN FLOW AND
REBOUNDING HEIGHTS SIGNAL GRADUAL WARMING OF THE COLUMN
CHARACTERIZED BY H85 TEMPS RISING TO AROUND 10C. INCREASED
INSOLATION COMPARED TO RECENT DAYS WILL FACILITATE DEEPER MIXING AND
SUBSEQUENTLY WARMER TEMPERATURES WHICH SHOULD EASILY REACH THE MID
70S. HIGH CLOUDS WILL GRADUALLY INCREASE THROUGH THE DAY FOLLOWED BY
A HEALTHY COVERAGE OF HIGH BASED CU BY THIS AFTN.

AT THE SAME TIME, THE WAVE OVER THE EASTERN GREAT PLAINS WILL LIFT
SLOWLY NORTHEAST, PRECIP LARGELY FOCUSED ALONG THE LLJ AXIS, BEFORE
SHEARING NORTHEAST MORE RAPIDLY ON FRIDAY NIGHT AS SYNOPTIC FLOW
RESPONDS TO CANADIAN ENERGY DIGGING INTO THE UPSTREAM SIDE OF THE
TROUGH. SUITE OF 00Z GUIDANCE OFFER HIGH CONFIDENCE THAT LLJ AXIS
WILL REMAIN SAFELY CONFINED TO THE WEST LIMITING CONCERNS TO WHAT
WILL PRESUMABLY BE LESS ORGANIZED SHOWER ACTIVITY ASSOCIATED WITH
THE SHEARING PV FILAMENT RACING ACROSS NORTHERN LOWER.
WEAK/TRANSIENT NATURE OF FORCING AND A DRY COLUMN DOES LITTLE TO
INSPIRE CONFIDENCE IN THE MORE AGGRESSIVE QPF OUTPUT IN SOME OF THE
GUIDANCE. TRENDED THE FORECAST POPS OVERNIGHT CONSIDERABLY DOWNWARD
IN ACCORDANCE WITH ARW/NMM/RGEM CONSENSUS. THETA-E ADVECTION WILL
SUPPORT DEWPOINTS HOVERING NEAR 60 TONIGHT, SERVING AS THE
APPROXIMATE FLOOR FOR LOW TEMPS.

LONG TERM...SATURDAY THROUGH THURSDAY

CLOSED MID LEVEL LOW CURRENTLY LIFTING EAST INTO THE MID MISSISSIPPI
VALLEY WILL GRADUALLY ELONGATE INTO A LONGER WAVE TROUGH OVER THE
NEXT SEVERAL DAYS...WITH ADDITIONAL SHORTWAVE ENERGY FUNNELING INTO
THE EXISTING LOWER HEIGHT FIELD SUSTAINING SOME DEPTH TO THIS
FEATURE AS IT WORKS ACROSS THE GREAT LAKES BY THIS WEEKEND.  INITIAL
CORRIDOR OF GREATER MOISTURE ADVECTION IMMEDIATELY DOWNSTREAM WILL
TEND TO FOCUS WITHIN A REGION OF WEAK ISENTROPIC ASCENT POSITIONED
FROM NORTHERN IL/SOUTHERN WI INTO CENTRAL AND NORTHERN LOWER MI FROM
LATE TONIGHT INTO EARLY SATURDAY.  THIS LEAVES THE TRI-CITES/THUMB
REGION MORE FAVORABLY POSITIONED TO SEE SOME EARLY DAY SHOWER
DEVELOPMENT ON SATURDAY.  STEADY IMPROVEMENT IN MOISTURE QUALITY
/PW EXCEEDING 1.4/ ARRIVING IN CONJUCTION WITH INCREASING DCVA AND
SOME DEGREE OF MID LEVEL DEFORMATION AS THE FRONTFACE OF THE TROUGH
ENTERS THE REGION WILL THEN BRING AN INCREASING CHANCE FOR SHOWERS
AREAWIDE FROM MID-LATE AFTERNOON INTO THE EVENING HOURS.  MINIMAL
INSTABILTY THROUGH THE COLUMN POINTS TO SIMPLY AN ISOLATED POTENTIAL
FOR EMBEDDED THUNDER.  A THICKER MID/HIGH CLOUD CANOPY IN ADVANCE OF
PRECIPITATION ONSET WILL CAP THE DIURNAL HEATING POTENTIAL...
AFTERNOON HIGHS TOPPING OUT IN THE 70S.

EXISTING MID LEVEL FORCING WILL PERSIST THROUGH SATURDAY NIGHT AS
THE MEAN TROUGH BASE SLOW PROGRESSES THROUGH THE REGION.  GIVEN THE
HIGHER MOISTURE CONTENT...THIS WILL CONTINUE TO SUPPORT A SCATTERED
TO NUMEROUS COVERAGE OF SHOWERS THROUGH THE NIGHT.  THIS PROCESS MAY
LAG INTO SUNDAY...WITH THE TRAILING CYCLONIC FLOW COMBINING WITH
DAYTIME HEATING TO PROVIDE A FAVORABLE ENVIRONMENT FOR SOME RENEWED
DEVELOPMENT.  GREATER PROSPECTS FOR AT LEAST PARTIAL SUNSHINE INTO
AN ALREADY SLIGHTLY WARMER LOW LEVEL THERMAL PROFILE WILL SUPPORT
HIGHS CLOSER TO 80 DEGREES.

CENTER OF THE MID LEVEL TROUGH/SHEAR AXIS WILL SETTLE INTO THE LAKE
ERIE/NORTHERN OHIO CORRIDOR EARLY NEXT WEEK.  UPPER RIDGE AXIS
BUILDING OVER THE TOP OF THIS FEATURE WILL SEEMINGLY PROVIDE A
RELATIVELY BENIGN STRETCH OF WEATHER ACROSS SE MICHIGAN.  THERE DOES
REMAIN THE POTENTIAL FOR A LINGERING COMPONENT OF CVA WITHIN THE
PERIPHERY OF THE EXITING TROUGH TO PROVIDE A LOW END OPPORTUNITY FOR
DIURNAL PRECIPITATION DURING THE EARLY WEEK PERIOD.  OTHERWISE...THE
INCREASING UPPER HEIGHTS WILL FAVOR A STRETCH OF ABOVE NORMAL WARMTH
BY THE MIDDLE AND END OF NEXT WEEK.

MARINE...

SURFACE HIGH PRESSURE WILL MAINTAIN RELATIVELY LIGHT WINDS OVER THE
CENTRAL GREAT LAKES TODAY. THE APPROACH OF A LOW PRESSURE SYSTEM
WILL THEN BRING AN INCREASE IN SOUTHEAST WINDS FOR SATURDAY...SPEEDS
AT 20 KNOTS OR LESS. THIS SYSTEM WILL ALSO PROVIDE A CHANCE FOR
SHOWERS WITH ISOLATED THUNDERSTORMS OVER THE WEEKEND.

&&

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

$$

AVIATION.....JVC
SHORT TERM...JVC
LONG TERM....MR
MARINE.......MR

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



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