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000
FXUS63 KDTX 171700
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
100 PM EDT MON JUN 17 2013


.AVIATION...

//DISCUSSION...

COLD FRONT DRAPED NEAR MBS TO LDM HAS STALLED OUT SOME WITH -TSRA
ORIENTED ALONG AND AHEAD OF THE FRONT. SURFACE OBS IN NORTHERN MI
HAVE CONFIRMED THAT INDICATE THE ACTIVITY IS HIGH-BASED WITH CLOUD
BASES NEAR 5-7.5K FEET. THIS WILL KEEP THE TAFS IN VFR MODE THROUGH
THE FORECAST...DESPITE THE POSSIBILITY FOR SHORT PERIODS OF VIS
DROPPING TO 5SM OR LESS WITHIN STRONGER STORMS. COLD AND DRY
ADVECTION COUPLED WITH A TIGHT PRES GRADIENT INTO TUES WILL BRING
WIND GUSTS OVER 20KT.

FOR DTW...THE PROBABILITY FOR THUNDERSTORMS TO IMPACT THE TERMINAL
WITH THE COLD FRONTAL PASSAGE CURRENTLY REMAINS TOO LOW TO INCLUDE
IN THE TAFS. FROPA LOOKS TO OCCUR AROUND 01-03Z.

//DTW THRESHOLD THREATS...

* LOW CONFIDENCE IN CEILINGS BELOW 5000 FT THIS AFTERNOON THROUGH
TONIGHT.

* LOW CONFIDENCE IN THUNDERSTORM POTENTIAL LATE THIS AFTERNOON
THROUGH TONIGHT.

&&

.PREV DISCUSSION...ISSUED 343 AM EDT MON JUN 17 2013

SHORT TERM...TODAY AND TONIGHT

GRADUAL HEIGHT FALLS SPREADING ACROSS THE UPPER GREAT LAKES EARLY
THIS MORNING...PROMPTED BY NUMEROUS WEAK PV FILAMENTS SHREDDING OFF
A PRIMARY SHORTWAVE NOTED ON WATER VAPOR EJECTING INTO NORTHERN
MINNESOTA.  THIS PROCESS WILL ALLOW A COLD FRONTAL BOUNDARY
CURRENTLY ANALYZED DRIFTING ACROSS NORTHERN LOWER MICHIGAN TO
PROGRESSIVELY SETTLE SOUTHWARD ACROSS SE MICHIGAN OVER THE NEXT 24
HOURS.  THESE WEAKER IMPULSES WORKING ACROSS A STEEPER MID LEVEL
LAPSE RATE ENVIRONMENT SEEMINGLY DRIVING THE ONGOING WIDELY
SCATTERED SHOWER ACTIVITY TRANSLATING FROM THE UPPER MS VALLEY INTO
NORTHERN/CENTRAL LOWER...AND WILL PROVIDE A LOWER END POTENTIAL FOR
POCKETS OF LIGHT PRECIPITATION TO IMPACT THE CORRIDOR NORTH OF I-69
DURING THE EARLY PART OF THE DAY.

GREATER PROSPECTS FOR SHOWER AND THUNDERSTORM DEVELOPMENT WILL FOCUS
INTO THE AFTERNOON AND EVENING PERIOD...AS THE ADVANCING FRONTAL
SLOPE ENTERS THE FORECAST AREA COINCIDENT WITH THE PEAK HEATING
CYCLE.  SOLID WINDOW WILL EXIST TO CAPITALIZE ON DAYTIME HEATING
GIVEN THE FRONTAL TIMING...A HIGH DEGREE OF PRE-FRONTAL INSOLATION
WORKING INTO A WELL MIXED WEST-SOUTHWEST FLOW AND RELATIVELY DRY
BOUNDARY LAYER WILL BRING HIGHS INTO THE 80 TO 85 DEGREE RANGE
ACROSS ALL BUT THE FAR NORTH.  THIS DEGREE OF WARMTH APPEARS
NECESSARY TO OVERCOME THE APPARENT LACK OF BETTER LOW LEVEL
MOISTURE /DEWPOINTS MID-UPPER 50S/.  THIS SUGGESTS CONVECTIVE
INITIATION WILL REQUIRE A GOOD PORTION OF THE DAY...DEVELOPMENT/
EXPANSION MOST FAVORED AFTER 20Z AS MLCAPE VALUES APPROACH 1500 J/KG
INVOF INCREASING FRONTAL CONVERGENCE ACROSS NORTHERN SECTIONS OF THE
AREA.  A SUPPRESSED HEIGHT FIELD WILL MAINTAIN STEEP MID LEVEL LAPSE
RATES THROUGH THIS TIME...PROVIDING A FAVORABLE ENVIRONMENT FOR
CONVECTION TO QUICKLY ATTAIN BETTER UPDRAFT STRENGTH WHERE THE LOW
LEVEL THERMODYNAMICS BECOME SUPPORTIVE.  A STRONG AND LARGELY
UNIDIRECTIONAL MID LEVEL WIND FIELD WILL BE IN PLACE...YIELDING 0-6
KM BULK SHEAR PUSHING 45 KNOTS.  AT THE VERY LEAST...GIVEN THIS WIND
FIELD AND LOWER FREEZING LEVELS...AN ISOLATED RISK FOR SEVERE WIND
GUSTS AND HAIL WILL EXIST.  THERE IS CERTAINLY THE POTENTIAL WITHIN
THIS SETUP FOR A MORE ORGANIZED CONVECTIVE EPISODE TO EVOLVE AND
EXPAND SOUTH/EAST WITH TIME THROUGH THE LATE EVENING HOURS.

DESPITE THE GRADUAL EROSION OF THE INSTABILITY RESERVOIR UNDER
NOCTURNAL COOLING INFLUENCES...INFUSION OF SLIGHTLY BETTER MID LEVEL
DYNAMICS AS THE MAIN SHORTWAVE SHEARS ACROSS THE FRONTAL BOUNDARY
WILL MAINTAIN A CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS SOUTHERN
SECTIONS INTO TONIGHT.  MODERATE POST-FRONTAL COOLING WITHIN
DEVELOPING NORTHEAST LOW LEVEL FLOW WILL PROVIDE A NOTICEABLE
DOWNWARD ADJUSTMENT TO TEMPERATURES TOWARD THE NORTH.  LOWS RANGING
FROM LOWER 50S NORTH TO NEAR 60 NEAR THE OHIO BORDER.

LONG TERM...TUESDAY THROUGH SUNDAY

LONGWAVE FEEDBACK ASSOCIATED WITH THE LARGE CLOSED LOW ENCROACHING
ON THE PAC NW WILL RESULT IN A GENERAL PATTERN OF LARGE SCALE HEIGHT
RISES OVER THE CENTRAL US/GREAT LAKES THROUGH THE FIRST HALF OF THE
WEEK. THIS WILL MAINTAIN SURFACE HIGH PRESSURE AND NORMAL LATE JUNE
TEMPERATURES OF 75-80 DEGREES FOR A DECENT STRETCH OF WARM/DRY SE MI
SUMMER WEATHER. THE SHEAR MAX CURRENTLY NOTED OVER SOUTHERN
SASKATCHEWAN DIVING INTO THE NORTHERN PLAINS THIS MORNING WILL PASS
JUST SOUTH OF THE AREA ON TUESDAY, BUT SHOULD BE OF LITTLE
CONSEQUENCE, ASIDE FROM SOME MODULATION OF LOCAL CLOUD COVER, SINCE
MONDAY`S SFC BAROCLINIC ZONE WILL HAVE ALREADY EASED WELL SOUTH OF
THE AREA. LONGWAVE RIDGING ENTRENCHED OVER THE CENTRAL CONUS IS THEN
PROGGED TO GET A NOTEWORTHY BOOST FOR THE LATTER HALF OF THE WEEK AS
BROAD ANTICYLONIC NOTED INVOF 25N/130W EAST OF HAWAII IS ENTRAINED
INTO PREVAILING SW UPPER FLOW. H5 HEIGHTS ARE PROGGED BY THE 00Z
ECMWF TO BUILD TO 595DM OVER TX BY FRIDAY AFTERNOON AS A RESULT.
LOCALLY, CONTINUED NORTHWEST FLOW ALOFT AND DOMINANCE OF SURFACE
HIGH PRESSURE IS FORECAST TO MAINTAIN NEAR NORMAL TEMPERATURES INTO
THE WEEKEND, WHEN THE PATTERN WILL POTENTIALLY BECOME RIPE WITH
CONVECTIVE POTENTIAL GIVEN SOUTHEAST MICHIGAN`S FAVORABLE LOCATION
ALONG THE EDGE OF THE CAP & ALONG THE LOW-LEVEL INSTABILITY GRADIENT.
THEREFORE, NO CHANGES NECESSARY TO INHERITED CHANCE POPS SAT-MON.

MARINE...

FAVORABLE MARINE CONDITIONS WILL PERSIST ACROSS AREA WATERWAYS
THROUGH THE EARLY PORTION OF THE DAY.  THE APPROACH OF A COLD FRONT
WILL BRING A CHANCE OF THUNDERSTORMS FROM MID AFTERNOON THROUGH
TONIGHT.  WINDS WILL TURN TO NORTHEASTERLY WITH THE FRONTAL
PASSAGE.  DRY AND STABLE CONDITIONS WITH HIGH PRESSURE TAKING
CONTROL TUESDAY AND WEDNESDAY.

&&

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

&&

$$

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


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