Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 070346
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1146 PM EDT WED MAY 6 2015


.AVIATION...

MARINE FOG HAS BEGUN TO PUSH WESTWARD WITHIN PREVAILING EASTERLY
FLOW IN EXTREME SOUTHEAST MICHIGAN. THIS FOG WILL PUSH INTO THE
DETROIT METRO AREA WITHIN THE NEXT COUPLE OF HOURS BRINGING IFR VSBY
RESTRICTIONS. FURTHER INLAND...FOG WILL BE MORE STRONGLY DEPENDENT
ON RADIATING WHICH WILL NOT BE TERRIBLY STRONG. AS SUCH...EXPECT
MAINLY MVFR OR HIGH IFR VARIETY RADIATION FOG FOR KFNT/KMBS. VSBYS
WILL IMPROVE AFTER SUNRISE GIVING WAY TO VFR AND LIGHT WIND OUT OF
THE SOUTHERLY QUADRANT FOR THURSDAY. SUSPECT FOG MAY TRY TO HOLD ON
A BIT LONGER IN THE DETROIT AREA DUE TO REINFORCING FLOW OFF OF LAKE
ERIE.

FOR DTW...VSBY RESTRICTION WILL BE REINFORCED EARLY THURSDAY BY
SOUTHEAST FLOW OFF OF LAKE ERIE. CURRENT FORECAST CALLS FOR FOG TO
MIX OUT AT ESSENTIALLY THE CLIMATOLOGICALLY FAVORED TIME.
HOWEVER...IT IS NOT OUT THE QUESTION THAT FOG HANGS ON AN EXTRA HOUR
OR TWO.

//DTW THRESHOLD PROBABILITIES...

* LOW FOR VISBY TO FALL AOB 1/2 MILE.

&&

.PREV DISCUSSION...ISSUED 338 PM EDT WED MAY 6 2015

SHORT TERM...TONIGHT

A GROWING BOUNDARY LAYER THIS AFTERNOON HAS LED TO RISING CEILING
HEIGHTS AND DISSIPATION OF LOW CLOUD ACROSS SOUTHEASTERN MICHIGAN.
THUS FAR...SURFACE DEWPOINTS HAVE BEEN HOLDING ON IN THE UPPER 50S
ACROSS MOST OF THE AREA WHICH IS FAIRLY IMPRESSIVE GIVEN THE
BACKGROUND EASTERLY FLOW TRAJECTORY. THE MODELS ARE ADVERTISING A
COUPLE OF THINGS FOR THIS EVENING. THE FIRST IS A MUTED LAKE BREEZE
RELEASE TIMED WITH THE EARLY EVENING TRANSITION. THIS SHOULD KNOCK
SURFACE DEWPOINTS DOWN A FEW DEGREES WITH SURFACE STABILIZATION
ALONG WITH A MODEST WESTWARD EXPANSION OF SURFACE HIGH PRESSURE. THE
SECOND IS AN ANTICYCLONIC GYRE THAT IS EXPECTED TO LIFT
NORTHEASTWARD INTO SOUTHWESTERN LOWER MICHIGAN THAN ROLL EASTWARD
ACROSS THE CWA. MODELED RH/EQUIVALENT POTENTIAL TEMPERATURES
SUGGESTS A PERIOD OF DEEP DRY AIR ADVECTION OVERNIGHT COINCIDING
WITH THIS ANTICYCLONIC FEATURE. AS A RESULT...NOT EXPECTING ANYWHERE
NEAR THE SAME SETUP FOR TONIGHT AS LAST NIGHT AS SKIES ARE EXPECTED
TO CLEAR OUT. ALL INDICATIONS ARE FOR A FAVORABLE RADIATIVE COOLING
ENVIRONMENT. NAM IS FAIRLY BULLISH WITH NEAR SURFACE PROFILE
INDICATIVE OF FOG. FOR CONTINUITY...WILL MAINTAIN THE INHERITED
MENTION OF AREAS OF FOG IN THE PUBLIC FORECAST FOR TOMORROW MORNING
BUT NO DENSE FOG IS EXPECTED AT THIS TIME.

LONG TERM...THURSDAY THROUGH TUESDAY

ACTIVE WEATHER PATTERN SETTING UP FROM THE BEGINNING OF THE WEEKEND
THROUGH MONDAY AS A DEEP TROUGH OVER THE SW CONUS AND RIDGE OVER THE
EASTERN CONUS...AND INTO THE GREAT LAKES...ALIGNS A FRONTAL BOUNDARY
ACROSS THE REGION. THE UPPER LOW WILL EJECT SEVERAL SHORTWAVES
THROUGH THE SW FLOW WHICH WILL RIDE ALONG THE FRONT BRINGING
ENHANCED PERIODS OF SHOWERS AND TSTORMS TO THE AREA THIS WEEKEND.
TIMING THESE WAVES ALONG WITH FRONTAL TIMING WILL BE THE MAIN
CHALLENGE WHEN CONSIDERING POTENTIAL FOR STRONG THUNDERSTORMS.

TO WRAP UP THE WORK WEEK THE MAIN STORY WILL BE WARMTH AS HIGH
TEMPERATURES REACH 80+ DEGREES BOTH THURSDAY AND FRIDAY. BY THE
START OF THE DAY THURSDAY...THE 900-950MB LAYER WILL BE APPROACHING
20C WHILE TEMPS AT 850MB WILL BE RESPECTABLY IN THE LOW TEENS. THE
MID/UPPER LEVEL RIDGE AXIS WILL LIFT UP AND THROUGH LOWER MI
ALLOWING THE WARM SECTOR INTO THE REGION. THIS AS THE FRONT LOSES
DEFINITION WITH DEEP MIXING COMMENCING. THIS COMBINED WITH A GOOD
DEAL OF MAY SUNSHINE SHOULD ALLOW TEMPS TO EARLY REACH 80 DEGREES.
WE WILL NOT BE WITHOUT MOISTURE AS SFC DEWPOINTS START OFF IN THE
MID 50S...BUT THERE WILL BE NO FORCING MECHANISM TO REALIZE THAT
MOISTURE. BEST LL DYNAMICS WILL RESIDE TO THE WEST CLOSER TO THE
APPROACHING COLD FRONT.

ON FRIDAY...WARM AIR ABOVE THE INVERSION WILL QUICKLY MIX BACK DOWN
TO THE SFC ALLOWING RAPID ASCENSION BACK INTO THE 80S. THIS AIDED BY
DEEPER AND STRONGER SW FLOW BRINGING IN INCREASINGLY WARMER AND
MOISTER AIR TO SOUTHERN MI...WITH DEWPOINTS RISING INTO THE LOW 60S.
MOST OF THE AREA WILL SEE A SLIGHT UPTICK IN TEMPERATURES OVER
THURSDAY...BUT INCREASING CLOUD FIELD MOVING IN FROM THE WEST WILL
LIMIT HIGH TEMPS IN THE AFTERNOON. AS MENTIONED PREVIOUSLY...TIMING
OF MID LEVEL SHORTWAVE ENERGY WILL BE IMPORTANT FRIDAY. MODELS
HINTING AT A WEAK PREFRONTAL WAVE ROUNDING THE RIDGE BUT WITH NO
SUPPORT TO CONVECT FRIDAY AFTERNOON. LOOKS LIKE THE STRONGER WAVE
HOLDS OFF TIL FRIDAY NIGHT AS THE FRONT WILL BE CLOSER TO THE AREA.
MAY SEE ACTIVITY OVER WESTERN LOWER MI WITH THE SLOW MOVING FRONT
DURING FRIDAY AFTERNOON WITH THE EDGE OF THE DEEPER MOISTURE AND
THETA E GRADIENT APPROACHING THE US23 CORRIDOR. WILL GO WITH A
SLIGHT CHANCE TO LOW CHANCE POP FRIDAY TO ACCOUNT FOR POSSIBLE STRAY
SHOWERS THAT SPREAD INTO THAT AREA. BETTER CHANCES COMING
LATE EVENING AND OVERNIGHT THOUGH AS THE FRONT DRAWS NEARER.

CURRENT TREND HAS THE COLD FRONT PUSHING INTO WESTERN SE MICHIGAN
FRIDAY AND GENERATING SHOWERS ACROSS THE AREA THROUGH THE WEEKEND.
EURO SHOWS A NICE BUMP IN THE CAPE FOR SATURDAY AFTERNOON THAT COULD
HELP PULL THE TRIGGER ON THUNDERSTORM DEVELOPMENT...PARTICULARLY
LATE MORNING THROUGH EVENING. HIGHER CAPE VALUES APPEAR TO SETTLE A
LITTLE FURTHER SOUTH ON SUNDAY...BUT THERE SHOULD STILL BE ENOUGH
ENERGY REMAINING OVER SE MI TO KEEP THE THUNDERSTORM POTENTIAL IN
THE MIX FOR SUNDAY. ON THE HEELS OF THE SLOW MOVING WEEKEND COLD
FRONT...A CUTOFF LOW EMERGES OUT OF THE DESERT SOUTHWEST MONDAY. IF
THIS PANS OUT...IT COULD KEEP SHOWER AND THUNDERSTORM ACTIVITY ALIVE
AND WELL IN THE FORECAST THROUGH TUESDAY...AND POSSIBLY INTO
WEDNESDAY.

MARINE...

HIGH PRESSURE OVER THE REGION WILL DRIFT EASTERLY OVERNIGHT ALLOWING
WINDS TO BECOME SOUTHWESTERLY THURSDAY AND FRIDAY. THE LIGHT WINDS
WILL INCREASE SOME BY FRIDAY AS GRADIENT INCREASES AHEAD OF AN
APPROACHING COLD FRONT. BOTH MOISTURE AND TEMPERATURES WILL
INCREASES IN THE PREFRONTAL AIRMASS WHICH WILL MAKE CONDITIONS MORE
FAVORABLE FOR SHOWERS AND THUNDERSTORMS BY FRIDAY EVENING. RISK FOR
THUNDERSTORMS WILL CONTINUE THROUGH AT LEAST THE FIRST HALF OF THE
WEEKEND. IN ADDITION...THE POTENTIAL WILL EXIST FOR MARINE FOG TO
DEVELOP AS THIS WARM/MOIST AIR MOVES ACROSS THE COLDER LAKE WATERS.

&&

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

$$

AVIATION.....JVC
SHORT TERM...CB
LONG TERM....DRK/DE
MARINE.......DRK


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