Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 251908
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
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.

&&

.AVIATION...ISSUED 1255 PM EDT SAT JUL 25 2015

A COLD FRONT WAS LOCATED FROM OSC TO MKG AND WILL MOVE THROUGH
SOUTHEAST MICHIGAN THIS AFTERNOON AND EVENING. SHOULD GET THROUGH
MBS BY 20Z...FNT BY 21-22Z AND DTW BY 00Z THIS FRONT WILL BRING A
WINDOW OF LOWER CIGS AND POSSIBLE TSTORMS. VFR CONDITIONS WILL
PREVAIL BOTH BEFORE AND AFTER THIS NARROW WINDOW OF THE FRONTAL
PASSAGE IN WHICH MVFR CIGS/VSBYS MAY OCCUR. CONFIDENCE IS LOW WITH
COVERAGE OF POTENTIAL TSTORMS AS SIGNALS ARE POINTING TO
ISOLATED/SCATTERED COVERAGE. WILL INCLUDE A BRIEF 2 HOUR TEMPO TO
ACCOUNT FOR THIS NARROW WINDOW OF POTENTIAL FOR PTK SOUTHWARD WITH
JUST SHOWERS FOR FNT/MBS DUE TO EARLIER TIMING AND LESS INSTABILITY.
NORTHERLY WINDS BEHIND THE FRONT WILL BRING DRIER AIR BACK TO THE
AREA ERODING THE CLOUDS THIS EVENING INTO THE OVERNIGHT FROM NORTH
TO SOUTH. WINDS HAVE BRIEFLY INCREASED FROM THE SW AHEAD OF THE
FRONT BUT WILL RELAX SOME OVERNIGHT AS WIND SWITCH TO NORTHERLY WITH
THE NEXT HIGH SETTLING IN.

FOR DTW...COLD FRONT LOOKS TO BE MOVING THROUGH DURING PEAK
HEATING...WARRANTING THE TEMPO FOR TSTORMS FROM 21-23Z. UPSTREAM OBS
AND FORECAST SOUNDINGS SUGGEST CIGS WILL HOVER NEAR THE VFR/MVFR
THRESHOLD BUT THINKING IS VFR WILL DOMINATE WITH MVFR BEING MORE
SCATTERED SO WILL FAVOR VFR WITH THE TAFS.

//DTW THRESHOLD PROBABILITIES...

* MEDIUM FOR CIGS AOB 5KFT THIS AFTERNOON AND EVENING.

* LOW FOR THUNDERSTORMS THIS AFTERNOON.

&&

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

$$

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


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


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