Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 010756
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
356 AM EDT WED JUL 1 2015

.SHORT TERM...THIS EVENING AND TONIGHT

LOW LEVEL CYCLONIC FLOW WILL FINALLY LOOSEN ITS GRIP ON SOUTHEASTERN
MICHIGAN TODAY AS THE DEEP EASTERN NOAM TROUGH FADES EASTWARD AND
SURFACE HIGH PRESSURE BEGINS TO IMPINGE UPON THE GREAT LAKES REGION.
A RIBBON OF ANTICYCLONIC VORTICITY...ACCOMPANIED BY A SOLID SIGNAL
IN MIDLEVEL ANTICYCLONIC FLOW TRAJECTORIES...WILL FORCE ENOUGH
ACTIVE SUBSIDENCE TO BRING HIGH CONFIDENCE IN DEEP DRY AIR ADVECTION
TO SOUTHEASTERN MICHIGAN TODAY. THIS WILL SUBSTANTIALLY LOWER THE
POP CHANCES FOR THE AREA. THERE APPEARS TO BE ENOUGH MOMENTUM BEHIND
AN OLD WASHED OUT FRONTAL BOUNDARY TO COAST SOUTHWARD DOWN LAKE
HURON...ONE LAST ARTIFACT CAST OFF FROM THE CLOSED LOW LAST WEEKEND.
THE MIDLEVEL CONVERGENCE AXIS IS SHOWN TO HARBOR ENOUGH 850MB RH
WITHIN IT TO BRING A SLIGHT/ISOLATED CHANCE OF A HIGH BASED SHOWER
POST 20Z TODAY. THERE ALSO APPEARS TO BE SOME DEPENDENCE ON LOWER
COLUMN EQUIVALENT POTENTIAL TEMPERATURE POOLING OFF OF LAKESHORE
CONVERGENCE NEAR SAGINAW BAY AND THE NORTHERN THUMB. BOUNDARY LAYER
MATURATION PROCESSES WILL BE AT PLAY AND SUSPECT THAT SOME
CONDITIONAL PERSISTENCE OF PRECIPITATION WOULD OCCUR SOUTHEASTWARD
INTO THE EARLY EVENING HOURS. HIGH TEMPERATURES TODAY WILL BE COOL
FOR JULY 1ST...WITH READINGS TOPPING OUT IN THE LOWER 70S FOR MOST
AREAS.

&&

.LONG TERM...THURSDAY THROUGH TUESDAY

SURFACE HIGH PRESSURE AND SHORTWAVE RIDGING ALOFT WILL SLIDE ACROSS
THE AREA THURSDAY. SHOULD BE A VERY QUIET DAY WITH JUST SOME CU
FORMING BENEATH AN INVERSION IN THE AFTERNOON AS DAYTIME HEATING
COMBINES WITH LINGERING MOISTURE. EAST FLOW...ALTHOUGH LIGHT...ON
THE EAST FLANK OF THE HIGH WILL KEEP WINDS OFF THE LAKES...LIMITING
MAX TEMPERATURES TO THE LOW AND MID 70S. GOOD RADIATIONAL COOLING
CONDITIONS AND DEWPOINTS FALLING BACK INTO THE 40S ACROSS MUCH OF THE
AREA THURSDAY NIGHT SHOULD MAKE FOR A CHILLY NIGHT WITH LOWS FROM
THE MID 40S TO MID 50S.

MODELS REMAIN IN GOOD CONSENSUS WITH AN UPPER TROUGH DROPPING
THROUGH ONTARIO FRIDAY INTO FRIDAY NIGHT...AND CONTINUE TO SHOW THIS
ENERGY REMAINING UN-PHASED WITH ENERGY PASSING THROUGH THE OHIO
VALLEY. SOLUTIONS DO HOWEVER LOOK A LITTLE MORE AMPLIFIED THAN OVER
THE PAST 24 HOURS. THIS IS DUE TO A TREND TO A MORE AMPLIFIED
PATTERN OVERALL ACROSS CANADA...BOTH WITH AN UPSTREAM RIDGE AND THEN
WITH AN UPPER LOW/TROUGH DROPPING INTO BRITISH COLUMBIA AND ALBERTA.
LATEST GFS AND EURO DROP A COLD FRONT AS FAR A NORTHERN MICHIGAN
FRIDAY NIGHT AND EARLY SATURDAY AS THE FIRST TROUGH CLIPS ACROSS
ONTARIO...BEFORE WASHING IT OUT. WILL HAVE TO WATCH TRENDS WITH
THIS...BUT STILL THINK A DRY FORECAST IS WARRANTED.

RIDGING AT THE SURFACE AND ALOFT WILL THEN BUILD BACK INTO THE AREA
LATE SATURDAY THROUGH SUNDAY NIGHT BEFORE THE NEXT SYSTEM SLIDES
THROUGH CENTRAL CANADA. MORE AMPLIFIED AND SLOWER SOLUTIONS FOR THE
UPPER LOW/TROUGH OVER CANADA OFFERED BY THE 00Z GFS/EURO/GEM SUPPORT
TRENDING POPS DOWN FOR SUNDAY NIGHT/MONDAY AND UP FOR MONDAY NIGHT
AND TUESDAY WHEN A COLD FRONT IS FORECAST TO SWEEP ACROSS THE AREA.

TEMPERATURES SHOULD GRADUALLY WARM THROUGH THE END OF THE WEEK AND
THE WEEKEND UNDER PREDOMINANTLY HIGH PRESSURE. THIS SHOULD BOOST
SOUTHEAST MICHIGAN MAX TEMPS TO THE UPPER 70S TO LOW 80S BY THE
WEEKEND.

&&

.MARINE...

A WEAK COLD FRONT DROPPING THROUGH THE CENTRAL GREAT LAKES WILL
BRING AN INCREASE IN NORTHWEST WINDS TODAY. SPEEDS SHOULD REMAIN
AROUND 15 KNOTS OR LESS. HIGH PRESSURE WILL THEN BEGIN TO EXPAND
INTO THE AREA...TAKING HOLD THROUGH FRIDAY AND PROVIDING FAIRLY
LIGHT WINDS AND QUIET WEATHER. A QUICK TROUGH WILL WORK THROUGH THE
AREA FRIDAY NIGHT...WITH LITTLE IMPACT EXPECTED. HIGH PRESSURE WILL
THEN REBUILD FOR THE HOLIDAY WEEKEND.

&&

.AVIATION...ISSUED 1207 AM EDT WED JUL 1 2015

THE MOST RECENT SURFACE ANALYSIS AND SATELLITE IMAGERY INDICATES A
BROAD AREA OF IFR/LIFR CEILING AND VISIBILITY OVER NORTHWEST LOWER
MICHIGAN. THESE CONDITIONS ARE SET TO SLIDE ACROSS THE REST OF THE
AREA IN NW LOW LEVEL FLOW TRAILING THE LOW PRESSURE SYSTEM OVER
SOUTHERN ONTARIO. THE PROCESS WILL BE ENHANCED BY THE CLEARING OF
MID LEVEL CLOUDS OVER WET GROUND WITHIN THE TERMINAL CORRIDOR.
DOWNSLOPE FLOW INTO MBS AND LINGERING GRADIENT SURFACE WIND WILL BE
FACTORS COMPLICATING COVERAGE AND POTENTIAL COMPONENT OF FOG VERSUS
STRATUS. THE FORECAST SIDES WITH MAINLY STRATUS FOR NOW. DAYTIME
HEATING WILL THEN HELP LIFT CEILING INTO VFR DURING THE AFTERNOON
INTO WEDNESDAY EVENING.

FOR DTW... CONFIDENCE HAS INCREASED ON TIMING AND COVERAGE MVFR/IFR
TRANSITION DURING THE NIGHT THEN LASTING THROUGH THE MORNING. PLAN
TO MONITOR CEILING TRENDS THAT COULD BRING THE FORECAST DOWN INTO
LIFR BY SUNRISE.

//DTW THRESHOLD PROBABILITIES...

* HIGH FOR CEILING 5000 FT OR LESS.

* LOW FOR CEILING LESS THAN 200 FT.

&&

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

$$

SHORT TERM...CB
LONG TERM....HLO
MARINE.......HLO
AVIATION.....BT


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


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