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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KDTX 190739
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
339 AM EDT WED JUN 19 2013

.SHORT TERM...
-- Changed Discussion --
TODAY AND TONIGHT

SPRAWLING HIGH PRESSURE SYSTEM EXTENDING FROM THE UPPER MS VALLEY TO
WESTERN QUEBEC WILL MAINTAIN CONTROL ACROSS THE REGION OVER THE NEXT
24 HOURS.  THIS WILL RETAIN A SEASONABLY COOLER AND MORE STABLE
ENVIRONMENT AS WEAK LOW LEVEL EASTERLY FLOW TUCKED BENEATH BROAD MID
LEVEL NORTHWESTERLIES LIMIT THE DIURNAL RECOVERY TO SIMPLE DIABATIC
HEATING PROVIDED BY STRONG MID JUNE SUNSHINE.  THIS WILL TRANSLATE
INTO HIGHS OF LOWER TO MIDDLE 70S...AGAIN SLIGHTLY COOLER ALONG THE
THUMB WITH THE ONSHORE WIND OFF THE COOLER WATERS CUTTING SLIGHTLY
INTO THE THERMAL RESPONSE.   A CLEAR SKY...WEAKENING GRADIENT AND
DRY PROFILE WILL AGAIN PROMOTE GOOD RADIATIONAL COOLING.  COLDEST
LOCALES AGAIN DIPPING INTO THE 40S.
-- End Changed Discussion --

&&

.LONG TERM...
-- Changed Discussion --
THURSDAY THROUGH TUESDAY

THE UPPER PATTERN ACROSS THE NORTHERN UNITED STATES WILL DEAMPLIFY
OVER THE NEXT COUPLE OF DAYS AS THE LARGE PAC NW LOW SHIFTS INLAND
AND EMBEDDED MID-LEVEL IMPULSES TRIGGER EPISODIC CONVECTION ACROSS
THE NORTHERN PLAINS. THE SIMULTANEOUS EASTWARD MIGRATION AND
DAMPENING OF THE DOWNSTREAM RIDGE OVER THE CENTRAL CONUS WILL FORCE
CANADIAN HIGH PRESSURE TO EXIT TO THE EAST AND FORCE SOUTHERLY
RETURN FLOW TO SPREAD INTO THE LOWER PENINSULA BEGINNING ON
THURSDAY. A NOTEWORTHY MODERATION OF TEMPERATURES WILL BE THE RESULT
AS DAYTIME HIGHS RISE TO 80 FOR THURSDAY AND SOLIDLY INTO THE
MID-80S ON FRIDAY, PARTICULARLY FOR WESTERN PORTIONS OF THE CWA AWAY
FROM POTENTIAL LAKE SHADOW IMPACTS.

A SIGNIFICANT TRANSITION IN THE LOCAL WX WILL THEN COMMENCE FROM
SATURDAY ONWARD AS MID-LEVEL WESTERLIES EMERGE ACROSS THE
NORTHERN TIER IN RESPONSE TO THE COLLAPSE OF THE MID-LEVEL RIDGE.
THIS WILL ALLOW A MOIST AND HUMID AIRMASS TO SPILL INTO THE REGION
WHICH SHOULD HAVE NO PROBLEM YIELDING HIGH TEMPERATURES NEAR 90
DEGREES ALONG WITH UPPER 60S/LOW 70S DEWPOINTS. GIVEN SOUTHEAST
MICHIGAN`S PROGGED FAVORABLE LOCATION ALONG THE INSTABILITY
GRADIENT AND NOSE OF THE VEERING LOW-LEVEL JET ON SATURDAY, HAVE
NO ARGUMENT WITH THE ECMWF`S SUGGESTION OF A CONVECTIVE COMPLEX
IMPACTING THE AREA ON SAT, PARTICULARLY GIVEN THE EXCELLENT
CONTINUITY OBSERVED IN RECENT CYCLES. WITH THIS IN MIND, LEANED
HEAVILY TOWARD A CONSERVATIVE HIGH TEMPERATURE FORECAST, AROUND 80
DEGREES, FOR SATURDAY.

THE RESERVOIR OF INSTABILITY AND ASSOCIATED SEVERE POTENTIAL WILL
CONTINUE TO BUILD SUNDAY INTO TUESDAY AS A ROBUST ZONALLY-ORIENTED
EML RIBBON BECOMES INCREASINGLY WELL-ESTABLISHED ACROSS THE GREAT
LAKES. PER THE USUAL, THIS WILL ALSO INTRODUCE STOUT MID-LEVEL
CAPPING AS EVIDENCED BY 00Z ECMWF 850MB TEMPS EXCEEDING 20C BY 00Z
MONDAY EVENING. AS A RESULT, BOTH HOT TEMPERATURES AND SEVERE
CONVECTIVE POTENTIAL WILL BE IN PLAY FOR SOUTHEAST MICHIGAN FROM
SUNDAY ONWARD. ALSO WORTH NOTING IS THAT MOIST BOUNDARY LAYER
CONDITIONS WILL LIMIT OVERNIGHT LOWS TO THE 70S.
-- End Changed Discussion --

&&

.MARINE...

-- Changed Discussion --
CANADIAN HIGH PRESSURE WILL MAINTAIN CONTROL ACROSS THE REGION
THROUGH THURSDAY.  THIS WILL PROVIDE A STRETCH OF FAVORABLE
MARINE CONDITIONS THROUGH THE END OF THE WEEK.
-- End Changed Discussion --

&&

.AVIATION...
-- Changed Discussion --
ISSUED 1234 AM EDT WED JUN 19 2013

//DISCUSSION...

VFR CONDITIONS EXPECTED THROUGH THE NEXT 24 HOURS AND BEYOND. HIGH
PRESSURE LOCKED OVER THE GREAT LAKES WILL PRODUCE FAVORABLE AVIATION
CONDITIONS THROUGH WEDNESDAY. CLEAR SKIES EXCEPT FOR A PATCH OF CI
TONIGHT AND THEN FEW TO SCT CU WEDNESDAY AFTERNOON. WINDS WILL
CONTINUE TO SLOWLY DIMINISH OVERNIGHT AND THEN VEER TO THE EAST.
LIGHT EAST WIND WILL CONTINUE ON WEDNESDAY AS THE HIGH DROPS FURTHER
SOUTH.

//DTW THRESHOLD THREATS...

* NONE
-- End Changed Discussion --

&&

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

&&

$$

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


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