Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 260354
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1154 PM EDT SAT JUL 25 2015

.AVIATION...

CLEAR SKIES AND NEARLY CALM WINDS TONIGHT COULD PRODUCE RADIATION
FOG...BUT ENOUGH URBAN HEAT ISLAND EFFECT AND DRY AIR IS EXPECTED TO
FILTER IN TO MIGITATE THE FOG POTENTIAL AT TAF SITES. HIGH PRESSURE
WILL REMAIN IN CONTROL TOMORROW...MAINTAINING LIGHT WINDS WITH JUST
A TOUCH OF CU (4-8 KFT) EXPECTED TOMORROW WITH DAYTIME HEATING.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

.PREV DISCUSSION...ISSUED 1007 PM EDT SAT JUL 25 2015

UPDATE...

WEAK COLD FRONT SHOULD REACH THE OHIO BORDER TOWARD
MIDNIGHT...EFFECTIVELY ENDING SHOWER/THUNDERSTORM THREAT.
THE ISSUE OVERNIGHT IS THE DRY AIR PUSH BEHIND THIS FRONT HAS
LOST MOMENTUM...AND ALTHOUGH MT PLEASANT DEW PT IS SITTING AT 54
DEGREES...SAGINAW REMAINS WITH A 71 DEW PT AT 10 PM. WITH CALM
WINDS TONIGHT...FOG IS BECOMING A CONCERN...ESPECIALLY ACROSS
THUMB REGION WHERE HEAVIER RAIN OCCURED. HOWEVER...STILL BANKING
ON THE DRIER AIR TO BLEED IN OVERNIGHT...MIGITATING THE FOG
THREAT...BUT WILL CONTINUE TO MONITOR TRENDS.

PREV DISCUSSION...ISSUED 308 PM EDT SAT JUL 25 2015

SHORT TERM...TONIGHT

DIFFUSE COLD FRONT WILL CONTINUE TO MOVE THROUGH SOUTHEAST MICHIGAN
DURING THE EVENING HOURS. DURING THE MID AFTERNOON THE FIRST FRONT
LIED FROM THE NW SIDE OF SAGINAW BAY TO MKG. SHOWERS AND STORMS WERE
DEVELOPING ALONG THIS FEATURE. THE MAIN PRESSURE TROF IS ASSOCIATED
WITH THIS SLIGHT WIND SHIFT TO THE WNW AND SLIGHTLY LOWER DEW
POINTS. THE DRIER AIR IS ASSOCIATED WITH SECOND FRONT AS WINDS TURN
TO THE NORTH FROM HARRISVILLE TO PENTWATER. ANALYSIS SUGGESTS THERE
IS SOME MOISTURE BEING ADVECTED AHEAD OF THESE FRONTAL SYSTEMS WITH
ML CAPES EXCEEDING 1000 J/KG. 0-6KM BULK SHEAR IS STILL ABOVE AROUND
35 KTS. THIS ALL SUGGESTS THAT THE CURRENT FORECAST THINKING OF
SCATTERED SHOWERS AND STORMS WITH AN ISOLATED THREAT OF A SEVERE
STORM IS STILL ON TARGET. HI RES RUNS ALSO STILL SUGGEST THAT BULK
OF THE ACTIVITY COULD BE DONE BY 22Z-00Z. THAT SECOND COLD FRONT MAY
BE ENOUGH TO TRIGGER A SHOWER OR STORM AND WILL ADD A SMALL CHANCE
POP FROM 00Z TO 03Z FOR AREAS SOUTH OF A PHN TO OZW LINE.

CLEARING TAKES PLACE FROM 00Z TO 06Z ACROSS THE FORECAST AREA AS THE
WINDS BECOMES LIGHT FROM THE NORTH.  GIVEN THE CLEAR SKIES AFTER
MIDNIGHT AND DEW POINTS BEHIND THE FRONT AROUND 60...WILL LOWER LOW
TEMPS A FEW DEGREES WHICH IS IN LINE WITH GUIDANCE NUMBERS TONIGHT.

LONG TERM... SUNDAY THROUGH MONDAY

PRETTY QUIET PERIOD AFTER FRONT PASSES THROUGH OVERNIGHT... WEAK
HIGH PRESSURE WILL CENTER ITSELF OVER THE GREAT LAKES WITH NEXT
PRECIP CHANCES HOLDING OFF UNTIL THE NEXT APPROACHING FRONT MID
WEEK. NOT MUCH IN THE WAY OF COLD ADVECTION BEHIND THE FRONT AND
WITH A LITTLE DRIER AIR MASS AND PLENTY OF SUN... EXPECTING GFS MAX
TEMPS NEAR 90 ARE LIKELY WITHIN REACH SUNDAY AND MONDAY. FAIRLY
LIGHT WINDS CONTINUING .. SFC DEW POINTS SHOULD NOT LOWER A HUGE
AMOUNT GIVEN THE HEALTHY STATE OF VEGETATION IN THE AREA.

UPPER RIDGE EXTENDING INTO THE WESTERN GREAT LAKES TUESDAY WILL GIVE
WAY TO LOWERING HEIGHTS WEDNESDAY AS AN UPPER LOW TRACKS ACROSS
SOUTHERN CANADA. THIS PROCESS WILL DRAG A COLD FRONT THROUGH
SOUTHEAST MICHIGAN IN THE WEDNESDAY/WED NIGHT TIME FRAME WHICH
RESULTS IN OUR NEXT CHANCE OF THUNDERSTORMS. VERY WARM AND HUMID
CONDITIONS WILL CONTINUE TUE/WED...WITH A COOLER/DRIER AIRMASS IN
THE OFFING FOR THE END OF THE WEEK IN THE WAKE OF THE COLD FRONT.

MARINE...

A FEW THUNDERSTORMS EARLY THIS EVENING ALONG THE COLD FRONT FROM FAR
SOUTHERN LAKE HURON AND POINTS SOUTHWARD. THIRTY KNOT WINDS NOT TOO
FAR OFF THE SURFACE ON THIS MORNINGS SOUNDING SO IT COULD GET A
LITTLE GUSTY ON THE LEAD EDGE OF THESE STORMS. AFTER THAT... LIGHT
WINDS AND NO PRECIP FOR THE NEXT 2-3 DAYS.  NEXT FRONT SHOULD
APPROACH THE AREA TUESDAY NIGHT BRINGING ANOTHER CHANCE OF
THUNDERSTORMS TO ALL OF THE LAKES.

&&

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

$$

AVIATION.....SF
UPDATE.......SF
SHORT TERM...RBP
LONG TERM....05/DT
MARINE.......05


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