000
FXUS63 KDTX 131653
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1253 PM EDT THU JUN 13 2013

.AVIATION...

//DISCUSSION...

SURFACE HEATING ACTING ON COOLER AIR SPREADING INTO LOWER MICHIGAN
WILL RESULT IN GENEROUS COVERAGE AND DEPTH OF CUMULUS DURING THE MID
TO LATE AFTERNOON. THE RESULTING VFR CEILING COULD ALSO SUPPORT A
LIGHT RAIN SHOWER NEAR THE TERMINAL SITES BUT WITH NO REAL
CONSEQUENCE TO AVIATION OPERATIONS. NORTHERLY WIND IS THEN EXPECTED
TO DIMINISH DURING THE EVENING ALONG WITH A GRADUAL DECREASE IN HIGH
BASED CU/LOWER AC. THE MORE CHALLENGING ASPECT OF THE FORECAST IS
FOR THE POTENTIAL OF STRATOCU COVERAGE FROM JUST BEFORE SUNRISE
THROUGH FRIDAY MORNING. VEERING FLOW ABOVE THE SURFACE BASED
INVERSION TO ABOUT 850 MB IS EXPECTED TO KEEP LOW LEVEL MOISTURE
OBSERVED OVER THE NORTHERN LAKES TODAY IN PLAY OVER THE SOUTHERN
LAKES LATER TONIGHT. THE POTENTIAL FOR MVFR CEILING LOOKS GREATER
FROM PTK INTO THE DTW AREA FOR NOW.

//DTW THRESHOLD THREATS...

* MEDIUM CONFIDENCE IN CEILINGS AT OR BELOW 5000 FEET THROUGH 01Z.

&&

.PREV DISCUSSION...ISSUED 339 AM EDT THU JUN 13 2013

SHORT TERM...TODAY AND TONIGHT

LOW PRESSURE SYSTEM CONTINUES TO TRACK SLOWLY EAST ACROSS THE AREA
EARLY THIS MORNING. MESO-LOW ASSOCIATED WITH LARGE CONVECTIVE
COMPLEX TO THE SOUTH HAS WRAPPED NORTHERN IN ADVANCE OF SYNOPTIC LOW
CENTER OVER FAR SOUTHERN LOWER MICHIGAN. MID LEVEL DRY SLOT WILL
SCOUR OUT DEEP MOISTURE ALONG/SOUTH OF THIS LOW PRESSURE AXIS. JUST
NORTH OF THIS DEFORMATION AXIS HAS SET UP...ALIGNED ESSENTIALLY WITH
THE M 59 AND I 94 CORRIDORS...WITH LESSER RAINS SURROUNDING THIS
AREA OF MAXIMUM LIFT/CONVERGENCE. EXPECT A SLOW BUT STEADY DECREASE
IN THIS ACTIVITY INTO DAYBREAK WITH ANY REMAINING SHOWERS IN FAR
SOUTHEAST LOWER MICHIGAN ENDING IN THE 12Z-14Z PERIOD.

NORTHERLY WINDS WILL BECOME A BIT GUSTY IN THE WAKE OF THIS LOW
PRESSURE SYSTEM AS THE PRESSURE GRADIENT TIGHTENS BETWEEN THIS
EXITING...AND STILL INTENSIFYING LOW PRESSURE...AND HIGH PRESSURE
SETTLING INTO THE NORTHERN GREAT LAKES FROM THE CANADIAN PRAIRIES.
WHILE THIS NORTHERLY FLOW WILL HELP TO DRY OUT...AND EVENTUALLY
CLEAR OUT...THE AREA...TEMPERATURES WILL REMAIN RELATIVELY COOL
WITH LOWER/MID 70S COMMON FOR HIGHS THIS AFTERNOON.

CLEARING SKIES AND LIGHT WINDS WILL ALSO LEAD TO RELATIVELY COOL
OVERNIGHT LOW TEMPERATURES TONIGHT. WOULD EXPECT LOWS IN THE 50 TO
55 DEGREE RANGE FOR THE MOST PART WITH SOME LOCATIONS EDGING INTO
THE 40S...ESPECIALLY OVER THE INTERIOR THUMB AND SAGINAW VALLEY.

LONG TERM...

UPPER LEVEL RIDGE OVER CENTRAL NORTH AMERICA WILL BE SLIDING EAST
OVER THE NEXT COUPLE OF DAYS...BUT THE TOP OF THE RIDGE OVER
NORTHERN CONUS/SOUTHERN CANADA WILL QUICKLY BE FLATTING OUT...AS
STRONG UPPER LEVEL LOW/TROUGH OVER THE PACIFIC NORTHWEST TRACKS TO
THE NORTHEAST INTO SOUTH CENTRAL CANADA OVER THE WEEKEND.

FRIDAY LOOKS TO BE THE ABOUT 5 DEGREES BELOW NORMAL AS NORTHERLY
FLOW OVER LAKE HURON WILL HELP OFFSET THE FULL SUNSHINE EXPECTED.
LATEST GUIDANCE SUPPORTS HIGHS IN THE UPPER 60S THUMB REGION TO MID
70S FAR SOUTH. SPRAWLING HIGH PRESSURE OVER SOUTHEAST MICHIGAN
FRIDAY NIGHT WILL PROVIDE A FAVORABLE RADIATING NIGHT...WITH LATEST
GUIDANCE SUGGESTING MINS IN THE MID 40S TO LOWER 50S. JUST FOR
REFERENCE...RECORD LOWS FOR JUNE 15TH ARE IN THE LOW TO MID 40S.

EXPECTING THE UPPER LEVEL RIDGE AXIS TO HOLD OVER THE CENTRAL GREAT
LAKES DURING THE DAYTIME HOURS OF SATURDAY. ALTHOUGH...IT WILL BE A
CLOSE CALL AS 850-700 MB THETA-E RIDGE AXIS LOOKS TO BE ARRIVING
AROUND 00Z SUNDAY. THIS MOISTURE AXIS COUPLED WITH MODESTLY UNSTABLE
AIRMASS WILL LEAD TO CHANCE OF SHOWERS AND THUNDERSTORMS SATURDAY
NIGHT THROUGH MONDAY BEFORE HEIGHTS CRASH EARLY NEXT WEEK AND DRIER
AIR FILTERS BACK INTO THE REGION UNDER THE NORTHWEST FLOW.

MARINE...

SHOWERS WILL END OVER SOUTHERN LAKE HURON EARLY THIS MORNING WITH
WIDESPREAD RAIN AND EMBEDDED THUNDERSTORMS ENDING SEVERAL HOURS
LATER OVER LAKE ST CLAIR AND WESTERN LAKE ERIE AS LOW PRESSURE
SHIFTS TO THE EAST. WITH THE EXIT OF THIS LOW...DRIER NORTHERLY WILL
GRADUALLY ERODE REMAIN FOG TODAY...BUT WIND GUSTS TO 20 KNOTS WILL
BRING AN INCREASE IN WAVES OVER SOUTHERN LAKE HURON. WILL ISSUE A
SMALL CRAFT ADVISORY FOR THE SOUTHERN TWO NEARSHORE ZONES WHERE THE
FETCH WILL BE MAXIMIZED AND WAVES WILL BUILD TO 3 TO 5 FEET MUCH OF
THE DAY. CONDITIONS WILL THEN CALM CONSIDERABLY HEADING INTO THE
WEEKEND AS A LARGE HIGH PRESSURE SYSTEM BUILDS OVER THE GREAT LAKES.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...NONE.

LAKE HURON...
     SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM HARBOR BEACH TO PORT
     HURON...UNTIL 4 PM THURSDAY.

LAKE ST CLAIR...NONE.

MI WATERS OF LAKE ERIE...NONE.

&&

$$

AVIATION.....BT
SHORT TERM...DG
LONG TERM....SF
MARINE.......DG


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