Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 041057
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
657 AM EDT SAT JUL 4 2015


.AVIATION...

MOSTLY CLEAR SKIES AND LIGHT WINDS WILL CONTINUE OVER THE NEXT 24
HOURS. SOME DIURNAL CU IS EXPECTED DURING THE DAY...ESPECIALLY OVER
FNT AND MBS WHERE A SURFACE TROUGH WILL BE IN CLOSE PROXIMITY. AN
ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE LATE TODAY AT MBS...WITH
ANY ACTIVITY QUICKLY DISSIPATING AROUND SUNSET...ALONG WITH CLOUDS.
SIMILAR TO THIS MORNING...PATCHES OF LIGHT FOG ARE POSSIBLE.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

.PREV DISCUSSION...ISSUED 315 AM EDT SAT JUL 4 2015

SHORT TERM...TODAY AND TONIGHT

UPPER LEVEL TROUGH AXIS PASSING THROUGH THE CENTRAL GREAT LAKES THIS
MORNING WILL BE REPLACED WITH UPPER LEVEL RIDGE BUILDING IN FOR
TONIGHT. THE MAIN QUESTION MARK IS WHETHER SUFFICIENT WARMING OF THE
MID LEVELS WILL OCCUR TO PREVENT ANY SHOWER/THUNDERSTORM ACTIVITY
FROM GOING UP THIS AFTERNOON...MAINLY JUST ACROSS FAR
NORTH...CLOSER TO 500 MB COLD POOL OF -15 TO -16 C OVER GEORGIAN
BAY. THE SURFACE TROUGH DID HAVE ACTIVITY OVER THE WESTERN GREAT
LAKES YESTERDAY EVENING...AND WITH 00Z REGIONAL GEM/NAM BOTH
INDICATING ACTIVITY OVER TRI-CITIES REGION/NEAR SAGINAW
BAY...SEEMS PRUDENT TO CARRY CHANCE POPS. HOWEVER...BOTH MODELS
SHOWING MOISTURE POOLING AND SURFACE DEW PTS INCREASING TO UPPER
60S...WHICH SEEMS A BIT EXCESSIVE...AND PREFER JUST A SLIGHT
CHANCE MENTION AS SBCAPES WILL PROBABLY PEAK OUT AROUND 1000 J/KG
WITH WEAK LOW LEVEL CAP IN PLACE. FURTHER MODIFICATION OF THE
AIRMASS TODAY UNDER A GOOD DEAL OF SUNSHINE...AS 850 MB TEMPS
ADVERTISED TO RISE BETWEEN 13 TO 14 C....WHICH SHOULD BE GOOD
ENOUGH FOR HIGHS AROUND 80 DEGREES. FAVORABLE RADIATING CONDITIONS
ONCE AGAIN TONIGHT...LIKELY ALLOWING MOST LOCATIONS TO DIP INTO
THE MID/UPPER 50S.

LONG TERM...SUNDAY THROUGH FRIDAY

LARGE SCALE SUBSIDENCE WILL PERSIST THROUGH THE DAY SUNDAY AS A MID
LEVEL RIDGE INFLUENCES LOWER MI. THIS WILL SUSTAIN A STRONG CAPPING
INVERSION...THUS INHIBITING ANY CONVECTIVE DEVELOPMENT. AMPLE MIXING
DEPTHS UNDER FULL INSOLATION WILL SUPPORT AFTERNOON HIGHS INTO THE
MID 80S. AMPLIFICATION OF A MID LEVEL TROUGH AXIS OVER THE DAKOTAS
SUN NIGHT AND MONDAY...ASSOCIATED WITH A NRN STREAM WAVE OVER
CANADA... WILL FORCE THE MID LEVEL RIDGE INTO THE ERN GREAT LAKES BY
MONDAY. THE 00Z MODEL SUITE ALSO SUGGESTS THE APPROACH OF THIS UPPER
TROUGH WILL HOLD DEEPER MOISTURE AND INSTABILITY ASSOCIATED WITH A
WEAK UPPER WAVE LIFTING UP FROM THE TN TO OH VALLEYS WELL SE OF THE
FORECAST AREA...THEREBY SUPPORTING ANOTHER DRY DAY OVER SE MI. THERE
WILL BE AN INCREASE IN THE S-SW GRADIENT OVER LOWER MI MON AHEAD OF
A COLD FRONT BEING DRIVEN INTO THE WESTERN GREAT LAKES. 850MB TEMPS
WILL RISE INTO THE UPPER TEENS IN RESPONSE. WITH FULL INSOLATION...
THIS WILL BOOST DAYTIME HIGHS INTO THE UPPER 80S/NEAR 90. THE
INCREASED GRADIENT WILL ALSO SUPPORT RELATIVELY MILD NIGHTTIME MINS
SUN AND MON NIGHTS IN COMPARISON TO THE LAST SEVERAL DAYS.

LARGE SCALE DYNAMICS WILL BE FAIRLY STRONG ACROSS THE FRONTAL
BOUNDARY MOVING THROUGH THE UPPER MIDWEST/WRN GREAT LAKES MON/MON
NIGHT DUE TO STRONG BAROCLINICITY FOR JULY. STRONG PREFRONTAL
SOUTHERLY FLOW WILL AID IN TRANSPORTING AMPLE DEEP LAYER MOISTURE
/PWATS POSSIBLY UP TO 2 IN/ INTO WI AND UPPER MI AHEAD OF THIS COLD
FRONT. THE 00Z MODEL SUITE SUGGEST THE UPPER JET AXIS AND BETTER MID
LEVEL HEIGHT FALLS WILL LIFT NORTH OF THE GREAT LAKES LATE MON NIGHT
INTO TUESDAY...WHICH SHOULD CAUSE THE FORWARD SPEED OF THE
ASSOCIATED SURFACE FRONT TO SLOW. IN TERMS OF THE 00Z MODEL
SUITE...THE GFS IS ALMOST 12 HOURS FASTER THAN THE
ECMWF/CANADIAN/NAM SOLUTIONS IN BRINGING THE SURFACE FRONT AND DEEP
LAYER MOIST AXIS ACROSS SE MI. THE GFS LOOKS TO HAVE SOME CONVECTIVE
FEEDBACK ISSUES. THIS AND IN LIGHT OF RECENT TRENDS...THE SLOWER
SOLUTIONS ARE PREFERRED ATTM...ALL OF WHICH INDICATE THE BETTER
CHANCES FOR CONVECTION WILL BE ON TUESDAY. COVERAGE OF SHOWERS AND
THUNDERSTORMS WILL BE SOMEWHAT DEPENDENT UPON THE DEGREE OF
DESTABILIZATION ON TUESDAY AS THE LARGE SCALE FORCING IS EXPECTED TO
WEAKEN AS THE FRONT PUSHES EAST. THE LATER FROPA OFFERED BY THE
ECMWF AND CANADIAN SUGGEST THERE WILL BE SOME DAYTIME
DESTABILIZATION AHEAD OF THE FRONT...SUPPORTING HIGH CHANCE TO
LIKELY POPS TUESDAY. A COOLER AND DRIER POST FRONTAL AIRMASS WILL
FILTER INTO THE AREA BY MIDWEEK AND MAY PERSIST THROUGH THE END OF
THE FORECAST PERIOD.

MARINE...

IDEAL BOATING CONDITIONS CAN BE EXPECTED THIS WEEKEND AS A WEAK
PRESSURE GRADIENT WILL PERSIST ACROSS THE GREAT LAKES. SOUTHERLY
WINDS WILL GRADUAL INCREASE SUN NIGHT INTO MONDAY AHEAD OF A COLD
FRONT APPROACHING THE WESTERN GREAT LAKES. STRONG OVER LAKE
STABILITY SHOULD HOLD GUSTS BELOW 20 KNOTS OVER THE LAKES. THE FRONT
IS FORECAST TO TRAVERSE THE REGION LATE MONDAY NIGHT INTO
TUESDAY...LEADING TO A VEERING OF THE WINDS TOWARD THE W-NW AND A
GOOD CHANCE OF SHOWERS AND THUNDERSTORMS.

&&

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

$$

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


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


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