000
FXUS63 KDTX 180657
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
257 AM EDT TUE JUN 18 2013

.SHORT TERM...TODAY AND TONIGHT

WEAK MID LEVEL SUBSIDENCE WILL GRADUALLY TAKE HOLD THROUGH THE
LATTER HALF OF THE MORNING IN THE WAKE OF A SHEARING MID LEVEL WAVE
AND ATTENDANT ENTRANCE REGION UPPER JET DYNAMICS EXPECTED TO SLIDE
TO THE SOUTH.  THIS WILL COMMENCE OVER INCREASING ANTICYCLONIC LOW
LEVEL FLOW DOWNSTREAM OF AN EXPANDING HIGH PRESSURE SYSTEM FILLING
INTO THE WESTERN GREAT LAKES.  STEADY BUT WEAK COLD AIR ADVECTION
COMMENCING WITHIN A NORTHEAST POST-FRONTAL GRADIENT WILL LEAD TO
NOTICEABLY COOLER CONDITIONS FOR TODAY.  SOME LINGERING EARLY DAY
CLOUD COVER WILL CONTRIBUTE TO THIS DOWNWARD THERMAL ADJUSTMENT.
A MODERATELY MIXED PROFILE INTO ROUGHLY 10C AT 850 MB TRANSLATES
INTO HIGHS OF MAINLY LOWER 70S...BUT WITH READINGS HELD MORE IN
CHECK /MID 60S/ ACROSS THE THUMB GIVEN THE COOLER LAKE INFLUENCE.

HIGH PRESSURE SETTLES INTO NORTHERN LOWER MI TONIGHT.  DEEP
DRY MID LEVELS AND A CLEAR SKY WILL CERTAINLY ENHANCE THE
RADIATIONAL COOLING...ALTHOUGH THE NORTHEAST WIND MAY NOT COMPLETELY
DECOUPLE ESPECIALLY ACROSS THE SOUTH WITH THE HIGH CENTER TO THE
NORTH.  REGARDLESS...THE STRENGTH OF THIS AIRMASS WILL SUPPORT
OVERNIGHT TEMPERATURES DROPPING INTO THE MIDDLE AND UPPER 40S
OUTSIDE OF THE DETROIT URBAN HEAT ISLAND.  THIS WILL LIKELY LEAVE
LOWS A COUPLE DEGREES SHY OF RECORD VALUES FOR THE DATE AT BOTH MBS
AND FNT /RECORD AT FNT 44...MBS 42/.

&&

.LONG TERM...WEDNESDAY THROUGH MONDAY

CANADIAN HIGH PRESSURE ENHANCED BY A LAKE AGGREGATE COMPONENT WILL
REMAIN IN PLACE THROUGH THURSDAY AS LONGWAVE RIDGING BUILDS
UPSTREAM. DEEP LAYER SUBSIDENCE ACROSS THE GREAT LAKES REGION WILL
FAVOR MOSTLY CLEAR SKIES WITH LITTLE MORE THAN A PARTIAL COVERAGE OF
HIGH-BASED CU EXPECTED ON BOTH WED AND THURS. HOWEVER, LIGHT
SOUTHEAST FLOW BENEATH THE NOCTURNAL INVERSION DOES RAISE SOME
CONCERN FOR LAKE-ENHANCED CLOUD COVER OFF OF LAKE ERIE FOR SOUTHEAST
AREAS WEDNESDAY NIGHT INTO THE FIRST PART OF THURSDAY.
TEMPERATURE-WISE, ONLY SLIGHT AIRMASS MODIFICATION IS EXPECTED FOR
WEDNESDAY AS BOUNDARY LAYER FLOW REMAINS WEAK TO VARIABLE WITH
ADVECTIONS VIRTUALLY NIL. HOWEVER, AS THE UPPER PATTERN FORCES THE
SURFACE HIGH EAST BY THURSDAY, ORGANIZING SOUTHERLY RETURN FLOW WILL
ALLOW TEMPERATURES TO REBOUND INTO THE UPPER 70S ON THURS AFTERNOON
AND LOW 80S BY FRIDAY. ATTENTION THEN TURNS TO THE WEEKEND WHEN
ENERGY EMANATING FROM THE LARGE PAC NW LOW WILL TRIGGER CONVECTION
ACROSS THE HIGH PLAINS AROUND THE NORTHERN PERIPHERY OF THE RIDGE. A
DEVELOPING LOW-LEVEL JET WILL HELP MAINTAIN THIS ACTIVITY AS IT
PROPAGATES ALONG THE INSTABILITY GRADIENT NEAR THE EDGE OF THE
MID-LEVEL CAP AND POTENTIALLY INTO SOUTHEAST MICHIGAN BY LATE FRIDAY
NIGHT OR EARLY SATURDAY MORNING.

&&

.MARINE...

STEADY NORTHEAST FLOW IN THE 10 TO 15 KNOT RANGE TODAY IN THE WAKE
OF A COLD FRONT.  THE ONSHORE FLOW WILL ALLOW WAVES TO BUILD ACROSS
SAGINAW BAY AND THE NEARSHORE WATERS OF LAKE HURON...BUT WITH WAVE
HEIGHTS LARGELY HOLDING WITHIN THE 2 TO 4 FOOT RANGE.  THIS WILL
PRECLUDE THE ISSUANCE OF A SMALL CRAFT ADVISORY FOR TODAY.  WINDS
WILL SLACKEN TONIGHT AS HIGH PRESSURE BUILDS INTO THE GREAT LAKES.
THIS HIGH WILL BRING A STRETCH OF FAVORABLE MARINE CONDITIONS WITH
LIGHT WINDS THROUGH THURSDAY.

&&

.AVIATION...ISSUED 1145 PM EDT MON JUN 17 2013

//DISCUSSION...

SEVERAL THUNDERSTORMS HAVE PUSHED THE SURFACE COLD FRONT SOUTH OF
THE TAF SITES...HOWEVER THE MID LEVEL COLD FRONT CONTINUES TO
GENERATE SHOWERS AS IT SLOWLY SINKS SOUTH. SHOWERS MAY CONTINUE FOR
ANOTHER HOUR OR TWO BEFORE INSTABILITY COMPLETELY WANES AS THE FRONT
HEADS SOUTH. IT APPEARS INSTABILITY HAS FALLEN ENOUGH TO CREATE A
NEAR NIL THREAT FOR THUNDER AS THE REMAINING ACTIVITY TRACKS THROUGH
FROM FNT SOUTHWARD...WITH MBS CLEAR OF ANY SHOWER THREAT. COLD AND
DRY ADVECTION COUPLED WITH A TIGHT PRES GRADIENT LATER ON TUESDAY
WILL BRING WIND GUSTS OVER 20KT WITH VFR CONDITIONS EXPECTED.

FOR DTW...THE PROBABILITY FOR THUNDERSTORMS TO IMPACT THE TERMINAL
WITH THE COLD FRONTAL PASSAGE CONTINUES TO BE VERY LOW...WITH A
CONTINUED THREAT FOR SHOWERS THROUGH 09Z.

//DTW THRESHOLD THREATS...

* LOW CONFIDENCE IN CEILINGS BELOW 5000 FT THROUGH 09Z.

* LOW CONFIDENCE IN THUNDERSTORM POTENTIAL THROUGH 09Z.

&&

.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.....KURIMSKI


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