Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 071947
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
347 PM EDT MON JUL 7 2014

.SHORT TERM...TONIGHT

SURFACE COLD FRONT HAS LOST SOME DEFINITION WITH DIURNAL MIXING THIS
AFTERNOON, BUT STILL REMAINS EASILY MARKED IN A SURFACE ANALYSIS AS
A DEWPOINT GRADIENT AND WEAK SURFACE TROUGH GRADUALLY EASING
SOUTHEAST THROUGH THE AREA. LOW-LEVEL THETA-E PLUME IN ADVANCE OF
THE FRONT HAS SUPPORTED HEALTHY COVERAGE OF CU IN ADDITION TO A FEW
SHOWERS/TSTORMS WITHIN AXIS OF ENHANCED CONVERGENCE INVOF
I-94...BOTH OF WHICH WILL DISSIPATE WITH THE LOSS OF HEATING THIS
EVENING. THIS AFTERNOON`S GRIDS REQUIRED ONLY COSMETIC ADJUSTMENTS
TO ACCOUNT FOR LOCATION OF SHOWERS. NO SOONER WILL THE MOISTURE AXIS
SLIP EAST OF THE AREA WILL SOUTHEAST MICHIGAN COME UNDER THE
INFLUENCE OF HEIGHT FALLS ASSOCIATED WITH VIGOROUS SHORTWAVE ENERGY
PRESENTLY OVER THE NORTHERN PLAINS. CORRESPONDING DEVELOPMENT OF
SOUTHERLY FLOW WILL LIMIT OVERNIGHT LOWS TO THE MID TO UPPER 60S FOR
MOST SPOTS. A FEW SHOWERS OR THUNDERSTORMS WILL BE POSSIBLE WITHIN
THE NORTHWARD SURGING CORRIDOR OF LOW-LEVEL MOISTURE AROUND SUNRISE,
HOWEVER THE BULK OF PRECIP SHOULD HOLD OFF UNTIL THE ARRIVAL OF MORE
ORGANIZED FORCING ALONG THE FRONT LATER TUESDAY MORNING.

&&

.LONG TERM...

ANOTHER WET AND POSSIBLY STORMY MORNING IS ON TAP TUESDAY FOR SE
MICHIGAN AS THE NEXT LOW PRESSURE SYSTEM TRACKS THROUGH THE NORTHERN
GREAT LAKES. THIS SYSTEM WILL BRING GENEROUS COVERAGE OF SHOWERS AND
THUNDERSTORMS THROUGH OUR AREA ALONG AND AHEAD OF THE ASSOCIATED
COLD FRONT. THE STRONGEST SHORT WAVE AND UPPER JET DYNAMICS WILL
OCCUR FARTHER NORTH...ALONG AND NORTH OF THE SURFACE LOW TRACK...BUT
ENOUGH OF THE SOUTHERN FRINGES OF THAT SUPPORT WILL BRUSH SE
MICHIGAN FOR ADEQUATE AUGMENTATION OF LOW TO MID LEVEL MOISTURE
TRANSPORT THAT WILL BE ONGOING AFTER SUNRISE. PROGRESSION OF THE
SYSTEM STILL LOOKS TOO FAST TO DRAW THE DEEPEST PORTION OF THE
MOISTURE AXIS NORTHWARD ALONG THE FRONT FROM THE OHIO VALLEY...BUT
SURFACE TO 700 MB THETA-E ADVECTION DOES APPEAR STRONG ENOUGH IN
MODEL DATA TO PROMOTE CONTINUED ELEVATED DESTABILIZATION AHEAD OF
THE COLD FRONT. WEAK COLD ADVECTION ALOFT WILL ALSO CONTRIBUTE TO
STEEPER LAPSE RATES BUT MODEL SOUNDINGS INDICATE A SKINNY CAPE
PROFILE GENERALLY LESS THAN 1000 J/KG AND A STABLE BOUNDARY LAYER
THERMAL PROFILE. THIS WILL BE A NEGATIVE FACTOR FOR STORMS REACHING
SEVERE LIMITS ALTHOUGH THE WIND PROFILE REMAINS OUTSTANDING FOR
ORGANIZATION OF STRONGER UPDRAFTS AS 0-6KM SHEAR WILL BE DIMINISHING
FROM NEAR 50 KNOTS BUT STILL ABOVE 35 KNOTS. THIS WILL REQUIRE CLOSE
MONITORING FOR PARCELS THAT BECOME SURFACE BASED...WHICH COULD OCCUR
BEFORE THE FRONT EXITS SE MICHIGAN...AS THE RESULTING INCREASED CAPE
DENSITY IN THE LOW LEVELS COULD PROMOTE FURTHER UPDRAFT ORGANIZATION
OF DISCRETE CELLS OR THE FORMATION OF LINEAR STRUCTURES IN MATURE
CONVECTION. OTHERWISE...INTERACTION OF THE SHORT WAVE DYNAMICS...THE
LOW LEVEL MOISTURE ADVECTION...AND COLD FRONTAL FORCING WILL RESULT
IN NUMEROUS COVERAGE OF SHOWERS IN SUPPORT OF THE GOING HIGH END
LIKELY FORECAST UNTIL THE FRONT SWEEPS EASTWARD OUT OF THE AREA BY
MID AFTERNOON.

A REINFORCING SURGE OF HEIGHT FALLS REMAINS ON TRACK FOR LATER
TUESDAY NIGHT THROUGH WEDNESDAY AS UPPER LEVEL JET ENERGY WITH POLAR
ORIGINS DIVES INTO THE DEEPENING LONG WAVE TROUGH OVER THE GREAT
LAKES. THE RESULTING SHORT WAVE ALOFT LOOKS PLENTY STRONG IN MODEL
DATA BUT WILL BE MOISTURE STARVED IN THE LOW LEVELS AFTER THE
TUESDAY FRONTAL PASSAGE. HOWEVER...STRONG COLD ADVECTION THE THE
UPPER LEVEL COLD POOL WILL HELP STEEPEN LAPSE RATES ENOUGH TO
COMPENSATE FOR THE LACK OF LOW LEVEL MOISTURE. THERE IS REASONABLE
MODEL AGREEMENT ON 500 MB TEMPS DROPPING DOWN TO NEAR -18C WHICH IS
PUSHING THE RECORD LOW FOR THE 10TH OF JULY IN THE DTX UPPER AIR
DATABASE. DAYTIME SURFACE HEATING WITHIN THE COOLER THAN NORMAL AIR
MASS WILL LIKELY ONLY BE ABLE TO LIFT TEMPERATURES INTO THE 70S BUT
THIS WILL RESULT IN ENOUGH DESTABILIZATION FOR AT LEAST SCATTERED
COVERAGE OF SHOWERS WITH A LONGER SHOT AT STORMS BY WEDNESDAY
AFTERNOON.

WEAK LOW PRESSURE WILL BEGIN MOVING INTO THE REGION BY LATE FRIDAY.
WARMING TEMPERATURES CAN BE EXPECTED AS THE SOUTHERLY FLOW RETURNS
AHEAD OF THE FRONT. EXPECT HIGH TEMPS TO BE IN THE LOW TO MID 80`S
FOR SATURDAY THROUGH MONDAY...ESPECIALLY OVER SOUTHERN SOUTHEAST
MICHIGAN. THE WARM UNSTABLE AIRMASS WILL KEEP CHANCES OF SHOWERS AND
THUNDERSTORMS IN THE FORECAST DURING THAT TIME FRAME AS WELL.

&&

.MARINE...

THUNDERSTORMS ALONG THE REMAINS OF THE MORNING FRONT WILL PROGRESS
TO THE SOUTH OF LAKE ERIE DURING THE EVENING WITH LITTLE MORE THAN A
STRAY SHOWER ELSEWHERE UNTIL AFTER MIDNIGHT. THAT IS WHEN A NEW
ROUND OF SHOWERS AND THUNDERSTORMS WILL DEVELOP AHEAD OF THE NEXT
LOW PRESSURE SYSTEM. INCREASING SOUTHWEST WIND AHEAD OF THE
ASSOCIATED COLD FRONT WILL LIFT WIND GUSTS TO NEAR 25 KNOTS OVER
SAGINAW BAY FOR A FEW HOURS BEFORE THE FRONT MOVES THROUGH THAT
AREA. EXPECT THE FRONT TO EXIT ALL MARINE AREAS BY MID AFTERNOON
TUESDAY. THE WEATHER WILL REMAIN UNSETTLED THROUGH WEDNESDAY WITH
SCATTERED SHOWERS AND A SMALL CHANCE OF THUNDERSTORMS BUT THE WIND
WILL BE LIGHT AND GENERALLY FROM THE NORTHWEST UNTIL HIGH PRESSURE
SETTLES IN BY THURSDAY. THE HIGH WILL REMAIN IN CONTROL OF MARINE
WEATHER BEFORE GETTING NUDGED OUT OF THE AREA BY THE NEXT FRONT DUE
SATURDAY.

&&

.AVIATION...ISSUED 1244 PM EDT MON JUL 7 2014

//DISCUSSION...

LOW VFR CLOUDS WITHIN THE LOW-LEVEL MOISTURE PLUME WILL SCATTER OUT
FROM NORTHWEST TO SOUTHEAST LATE THIS AFTERNOON INTO THIS EVENING AS
A WEAK COLD FRONT MOVES THROUGH THE AREA. IN THE MEANTIME...
LINGERING MVFR PORTION OF THE CLOUD DECK IS EXPECTED TO EITHER MIX
OUT COMPLETELY OR AT LEAST LIFT OUT OF THE MVFR CATEGORY WITHIN THE
NEXT COUPLE OF HOURS. WESTERLY WINDS WILL GUST TO 20-25KTS UNTIL THE
ONSET OF NOCTURNAL STABILIZATION THIS EVENING. MOSTLY CLEAR SKIES
THROUGH THE FIRST HALF OF THE NIGHT WILL ONCE AGAIN GIVE WAY TO
LOWERING CEILINGS AND A SHOWER/TSTORM THREAT IN ADVANCE OF ANOTHER
COLD FRONT 12-18Z TUESDAY.

//DTW THRESHOLD THREATS...

* HIGH CONFIDENCE IN CEILINGS BELOW 5KFT

* LOW CONFIDENCE THAT A THUNDERSTORM WILL IMPACT KDTW

&&

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

&&

$$

SHORT TERM...JVC
LONG TERM....BT/DE
MARINE.......BT
AVIATION.....JVC


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






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