Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 091635
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1235 PM EDT WED JUL 9 2014


.AVIATION...

//DISCUSSION...

WIDESPREAD LOW VFR CLOUDS WILL REMAIN PREVALENT THROUGH THE DAY
BEFORE DISSIPATING WITH THE LOSS OF HEATING THIS EVENING. WEAK UPPER
WAVE ROTATING ACROSS LAKE MICHIGAN WILL RESULT IN AN UPTICK IN
SHOWER COVERAGE ACROSS THE LOWER PENINSULA OVER THE NEXT COUPLE OF
HOURS, WITH THE MOST NORTHERLY LOCATIONS OF KMBS AND KFNT THE MOST
LIKELY TO BE DIRECTLY AFFECTED. WILL GO SO FAR AS TO INTRODUCE A
TEMPO FOR -SHRA AT KMBS BUT PREFER TO WAIT FOR FURTHER EVIDENCE AT
REMAINING LOCATIONS. HIGH PRESSURE WILL BRING CALM TO VARIABLE WINDS
ALONG WITH MOSTLY CLEAR SKIES FOR TONIGHT.

//DTW THRESHOLD THREATS...

* HIGH CONFIDENCE IN CEILINGS BELOW 5KFT

&&

.PREV DISCUSSION...ISSUED 339 AM EDT WED JUL 9 2014

SHORT TERM... TODAY AND TONIGHT

CONSOLIDATED SHORTWAVE ENERGY WORKING THROUGH THE EXISTING BROADER
MID LEVEL TROUGHING WILL SHIFT THE MAIN HEIGHT FALL CENTER/TROUGH
AXIS ACROSS THE STATE TODAY.  COOLER RESIDENT AIR MASS ALREADY IN
PLACE WITH 850 MB TEMPERATURES NOW EASING INTO THE UPPER SINGLE
DIGITS.  UNDER PARTIAL INSOLATION THIS WILL TRANSLATE INTO HIGHS OF
LOWER TO MIDDLE 70S...OR AROUND 10 DEGREE BELOW NORMAL.  BEST MID
LEVEL ASCENT TIED TO BOTH AN UPTICK IN CVA AND WITH THE PASSAGE OF
THE MAIN ATTENDANT COLD POOL WILL LARGELY TRANSLATE ACROSS NORTHERN
LOWER MI THIS MORNING.  GIVEN THE OVERALL POSITIONING AND LESS
SUPPORTIVE TIMING...THIS CONTINUES TO SUGGEST VERY LIMITED POTENTIAL
FOR SHOWER PRODUCTION PRIOR TO 18Z.  A GENERAL INCREASE IN CYCLONIC
FLOW ALONG THE SOUTHERN PERIPHERY...PERHAPS INDUCING SOME FORM OF
WEAK SURFACE TROUGHING/CONVERGENCE...WILL BEGIN TO FAVORABLY AUGMENT
THE STEEPENING LAPSE RATE ENVIRONMENT THROUGH PEAK HEATING.
GREATEST POTENTIAL FOR SCATTERED SHOWER DEVELOPMENT REMAINS FOCUSED
FROM THE TRI-CITIES SOUTHEAST DOWN THROUGH THE THUMB/PORT HURON
CORRIDOR.

LOSS OF HEATING WILL BRING A QUICK END TO ANY LINGERING SHOWERS THIS
EVENING.  HIGH PRESSURE THEN TAKES HOLD INTO TONIGHT AS THE EXISTING
MID LEVEL CYCLONIC FLOW EASES.  LOWS IN THE LOWER TO MIDDLE 50S
CERTAINABLE GIVEN THE OVERALL THERMAL PROFILE AND THE GENERAL LOSS
OF GRADIENT FLOW.

LONG TERM...

BROAD UPPER LEVEL TROUGH AXIS WILL BE DRIFTING EAST ON
THURSDAY...WITH LARGE SURFACE HIGH PRESSURE (1022 MB) IN CONTROL OF
LOWER MICHIGAN. JUST A REAL SMALL AREA OF CAPE IN BETWEEN 5000-8000
FOOT LAYER PER NAM SOUNDINGS...SO ALTHOUGH IT SHOULD END UP
DRY...EXPECTING A DECENT CU UP WITH AREAS OF MODEST LOW LEVEL
CONVERGENCE. 925 MB TEMPS OF 16 TO 18 C (PER 00Z EURO) SUPPORT
TEMPERATURES IN THE MID TO UPPER 70S...AS LIGHT FLOW AT THE SURFACE
WILL SUPPORT SUPERADIABATIC LAPSE RATES WITH THE EARLY JULY
INSOLATION.

UPPER LEVEL SHORTWAVE RIDGING FOR FRIDAY AS HIGH PRESSURE AT THE
SURFACE SLIDES OFF TO THE EAST...ALLOWING FOR SOME MODEST RETURN
FLOW/WARM ADVECTION...WHICH SHOULD HELP PUSH MAXES TO 80 DEGREES OR
SLIGHTLY BETTER...AS 850 MB TEMPS CLIMB INTO THE LOWER TEENS.

850 MB TEMPS WILL CONTINUE TO RISE INTO THE WEEKEND...BUT MOISTURE
WILL BE ON THE INCREASES AS WELL...WITH ENOUGH DESTABILIZATION TO
SUPPORT A CHANCE OF SHOWERS AND THUNDERSTORMS...AS A FEW SHORTWAVES
EJECT OUT OF THE CENTRAL/NORTHERN PLAINS...OUT AHEAD OF THE
DESCENDING POLAR VORTEX WHICH WILL BE TAKING RESIDENCE OVER ONTARIO
EARLY NEXT WEEK...RESULTING IN EXTENDING PERIOD OF BELOW NORMAL
TEMPERATURES. THE EXTREME TEMPERATURE GRADIENT/WIND FIELD (0-6 KM
SHEAR OF 55 KNOTS) WITH THE UNUSUALLY DEEP 500 MB LOW FOR JULY
COULD MAKE FOR AN INTERESTING MONDAY AS COLD FRONT TRACKS THROUGH
THE AREA...BUT TIMING WILL BE EVERYTHING.

MARINE...

A COOLER AND DRIER AIRMASS WILL CONTINUE TO MAKE INROADS INTO THE
CENTRAL GREAT LAKES...AS WINDS WILL CONTINUE OUT OF THE WEST
TODAY...BUT GENERALLY UNDER 15 KNOTS. THE EXCEPTION BEING OVER THE
NORTHERN THIRD OF LAKE HURON WHERE SOME CHANNELING WILL SUPPORT
WINDS TO AROUND 20 KNOTS. HIGH PRESSURE OVER THE REGION THURSDAY
WILL ASSURE THE LIGHT WINDS AND LOW WAVES EVERYWHERE...RIGHT INTO
FRIDAY. WARMER TEMPERATURES AND INCREASING MOISTURE WILL ARRIVE FOR
THE WEEKEND...SUPPORTING A CHANCE OF SHOWERS AND
THUNDERSTORMS...OTHERWISE EXPECT LIGHT SOUTHERLY WINDS.

&&

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

&&

$$

AVIATION.....JVC
SHORT TERM...MR
LONG TERM....SF
MARINE.......SF


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





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