Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 272305
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
705 PM EDT MON JUL 27 2015


.AVIATION...

CLEAR SKIES (BELOW 25 KFT) WITH CALM/NEARLY CALM WINDS
TONIGHT...GIVING WAY TO VERY LIGHT EAST-SOUTHEAST WINDS TOMORROW.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

.PREV DISCUSSION...ISSUED 248 PM EDT MON JUL 27 2015

SHORT TERM...TONIGHT

STEADY RIDGE AMPLIFICATION DOWNSTREAM OF WEST COAST HEIGHT FALLS
WILL LOCK SURFACE HIGH PRESSURE INTO PLACE FOR THE BALANCE OF THE
NIGHT. CLEAR SKIES SAVE FOR SOME STRAY HIGH CLOUD ACROSS THE SOUTH
IN CONJUNCTION WITH A VERY LIGHT GRADIENT WILL SET THE STAGE FOR
DECOUPLING AND A GOOD NIGHT FOR RADIATING. PER 12Z MET GUIDANCE,
LOWERED OVERNIGHT LOWS JUST A COUPLE OF DEGREES INTO THE LOWER 60S
OUTSIDE THE METRO AREA.

LONG TERM... TUESDAY THROUGH NEXT MONDAY

HIGH PRESSURE AT THE SURFACE AND ALOFT MAINTAIN THEIR CONTROL OF
LOWER MI WEATHER ON TUESDAY. ONLY A FEW CU EXPECTED FROM MID
AFTERNOON WITH MAYBE SOME CI APPROACHING LATE IN THE DAY. NEARLY
FULL SUNSHINE AGAIN ON TUESDAY WILL ALLOW TEMPERATURES TO PUSH TO
AROUND 90 CLOSER TO THE MAV/GFS GUIDANCE.

ONE CHANGE FOR THE UPCOMING FORECAST IS TO BACK OFF THE CLOUDS AND
CHANCE POPS FOR LATER TUESDAY NIGHT. MODELS ARE ALL QUITE A BIT
SLOWER WITH THE ADVANCING/LEADING MOISTURE ASSOCIATED WITH THE NEXT
FRONT AND UPPER SYSTEM.  WITH MORE CLEAR SKIES FOR A LONGER TIME ON
TUESDAY NIGHT AND DRIER DEW POINTS WILL LEAN TOWARD THE COOLER
MET/NAM GUIDANCE VALUES.

CLOUDS QUICKLY INVADE ON WEDNESDAY MORNING AS THAT MOISTURE FINALLY
PUSHES OVER THE FORECAST AREA. GOOD RIBBON OF MOISTURE WITH THE
SURFACE FRONT MOVING THROUGH THE REGION AND A LEAD SHORTWAVE
ASSOCIATED WITH THE MAIN TROF TO THE NW OF THE REGION WILL BE GOOD
ENOUGH TO BRING IN HIGH CHANCE POPS...50 PERCENT...FOR MUCH OF THE
NORTHERN CWA WHILE THE POPS WILL DECREASE FARTHER ACROSS THE
SOUTHERN PART OF THE FORECAST AREA. ML CAPES BUILD QUICKLY TO 1000
TO AROUND 1500 J/KG BY WEDNESDAY AFTERNOON. MID LEVEL LAPSE RATES
ARE MODEST FROM 5 TO 6C/KM WITH WEAK FLOW ALOFT. 0-6KM SHEAR IS IN
THE 20-30 KNOT RANGE. THIS SHOULD BE ENOUGH FOR SOME THUNDERSTORM
DEVELOPMENT AND ORGANIZATION...BUT NO MORE OF A SEVERE THREAT THAN
WHAT IS OUTLINED IN THE SPC DAY3 OUTLOOK.  THAT MARGINAL MAY BE ON
THE HIGH END GIVEN THE WEAKENING NATURE OF THE SURFACE
FRONT...WARMING TEMPS THROUGH THE DAY FROM 700 TO 500 MBS...WEAK
WINDS THROUGH THE COLUMN AND A JET AXIS TOO FAR TO THE NORTHWEST OF
THE GREAT LAKES REGION.

BEHIND THE FRONT...DRYING TAKES PLACE AFTER ABOUT 03Z WEDNESDAY
NIGHT. SHOULD HAVE MOSTLY CLEAR SKIES BY DAYBREAK THURSDAY.  THAT
DRY AIR SHOULD BRING ANOTHER DAY OF NEARLY FULL SUNSHINE ON THURSDAY
WITH JUST SLIGHTLY COOLER TEMPERATURES AND NOTICEABLY DRIER DEW
POINTS.

BROAD UPPER TROUGH SITUATED OVER THE NORTHERN TIER OF THE
CENTRAL/EASTERN US FRI/SAT...THOUGH MAIN JET ENERGY STAYS NORTH OF
THE INTERNATIONAL BORDER. WILL KEEP POPS OUT OF THE FORECAST UNTIL
SATURDAY NIGHT DUE TO LACK OF FORCING DEPICTED BY 12Z MODEL SUITE.
MORE CONCERTED HEIGHT FALLS ALONG WITH A SURFACE WAVE ADVERTISED FOR
SUNDAY/SUN NIGHT COULD PROVIDE NEXT CHANCE FOR MEANINGFUL PRECIP.
TEMPS EXPECTED TO BE SLIGHTLY ABOVE NORMAL FRI/SAT...EASING TO
SLIGHTLY BELOW NORMAL SUN INTO EARLY NEXT WEEK.

MARINE...

SURFACE HIGH PRESSURE WILL MAINTAIN LIGHT WIND CONDITIONS THROUGH
TUESDAY TONIGHT. SOUTHWEST WINDS WILL INCREASE MODESTLY ON WEDNESDAY
AS A COLD FRONT APPROACHES FROM THE WEST. THOSE MODESTLY STRONG
WINDS WILL TURN TO THE WEST FOR THURSDAY BEHIND THE COLD FRONT.

&&

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

$$

AVIATION.....SF
SHORT TERM...JVC
LONG TERM....RBP/DT
MARINE.......RBP


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



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