000
FXUS63 KDTX 160349
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1149 PM EDT WED MAY 15 2013


.AVIATION...

//DISCUSSION...

WEAK HIGH PRESSURE BUILDING ACROSS THE AREA AND VERY DRY LOW LEVEL
AIR WILL MAINTAIN LIGHT WINDS AND CLEAR SKIES BELOW 10K FT THROUGH
THE MORNING. A MODEST INCREASE IN THE WESTERLY WINDS WILL OCCUR BY
THURS AFTERNOON WITH THE ONSET OF DAYTIME HEATING.

//DTW THRESHOLD THREATS...

* NONE.

&&

.PREV DISCUSSION...ISSUED 549 PM EDT WED MAY 15 2013

UPDATE...

RECENT SATELLITE TRENDS SUPPORTED AN UPWARD ADJUSTMENT TO CLOUD
COVERAGE IN THE GRIDS THIS EVENING. THESE CLOUDS /NOW
OVERSPREADING THE SAGINAW VALLEY AND THUMB/ ARE ASSOCIATED WITH A
NARROW RIBBON OF MID LEVEL MOISTURE PRECEDING A WEAK MID LEVEL
IMPULSE TRACKING ACROSS CENTRAL LAKE MI. THIS WAVE WILL
WEAKEN/SHEAR APART AS IT TRACKS INTO LAKE HURON THIS
EVENING...WHICH SHOULD ALLOW SOME DIMINISHING TREND TO THESE MID
CLOUDS AS THEY EXIT TO THE EAST OF THE FORECAST AREA SHORTLY AFTER
MIDNIGHT. DESPITE THE RETURNS ON RADAR...AN ABUNDANCE OF LOW LEVEL
DRY AIR SHOULD INHIBIT ANY RAIN FROM REACHING THE GROUND OVER SE
MI.

PREV DISCUSSION...ISSUED 355 PM EDT WED MAY 15 2013

SHORT TERM...TONIGHT

GUSTY WINDS PRESENT ACROSS LOWER MICHIGAN WILL CONTINUE FOR THE REST
OF THE AFTERNOON AND INTO EARLY EVENING. WOULD NOT BE SURPRISED IF
MOST SITES SEE GUSTS BETWEEN 25 AND 30 MPH BEFORE THE WINDS DECREASE
AFTER SUNSET DUE TO THE LACK OF SURFACE HEATING. OTHERWISE...FAIRLY
QUIET CONDITIONS WILL EXIST TONIGHT AS HIGH PRESSURE BEGINS TO BUILD
INTO SOUTHEAST MICHIGAN. HIGH PRESSURE WILL KEEP THE STATIONARY
FRONT AND ALL PRECIPITATION TO OUR SOUTH ACROSS THE OHIO RIVER
VALLEY TONIGHT. A FEW LINGERING HIGH LEVEL CLOUDS MAY BE PRESENT
DURING THE OVERNIGHT HOURS...ESPECIALLY TOWARDS DAYBREAK AS THE
FRONT TO OUR SOUTH DRIFTS EASTWARD. MADE VERY MINIMAL CHANGES TO THE
PREVIOUS FORECAST IN REGARDS TO MINIMUM TEMPERATURES TONIGHT KEEPING
TEMPERATURES NEAR NORMAL FOR THIS TIME OF YEAR. THEREFORE...STILL
EXPECTING LOWS TO BE IN THE UPPER 40S /46 TO 49/ FOR MOST OF THE CWA
WITH THE EXCEPTION OF THE METRO DETROIT AREA WHICH WILL BE A FEW
DEGREES WARMER IN THE LOW 50S.

LONG TERM...THURSDAY THROUGH TUESDAY

SLIGHT HEIGHT FALLS ATTENDANT TO THE UPPER LOW NEAR JAMES BAY WILL
RESULT IN A SLIGHT SUPPRESSION OF THE THERMAL FIELD OVER SOUTHEAST
MICHIGAN FOR THURSDAY. HOWEVER, H85 TEMPS FALLING TO 10-12C UNDER
NEARLY FULL SUN WILL STILL FAVOR HIGHS APPROACHING 80 DEGREES, ABOUT
10 DEGREES ABOVE CLIMATOLOGICAL AVERAGE VALUES. SOUTHEAST
PROPAGATION OF LOW/MID LEVEL MOISTURE OVER NORTHERN MN THIS
AFTERNOON WILL RESULT IN A PARTIAL COVERAGE OF CU DURING PEAK
HEATING, BUT DRY LOW LEVELS WILL BE A SIGNIFICANT LIMITING FACTOR
FOR DIURNAL SHOWERS - WHICH SHOULD BE LIMITED TO JUST AN ISOLATED
SHOWER OR TWO WITHIN THE INLAND THERMAL TROUGH BUT NOTHING WORTH A
WX MENTION IN THE GRIDS.

BUCKLING OF THE UPPER FLOW AHEAD OF PAC ENERGY APPROACHING THE WEST
COAST WILL LEAD TO DOWNSTREAM RIDGE AMPLIFICATION OVER THE CENTRAL
CONUS BEGINNING ON THURSDAY. THE RESULTING SURFACE HIGH PRESSURE
WILL TRANSLATE NORTH OF THE CWA DURING THE PERIOD ENCOMPASSING
THURSDAY NIGHT THROUGH SATURDAY. THIS HELP WILL ENSURE COOL/STABLE
EASTERLY FLOW WITH HIGH TEMPERATURES MAXING OUT AROUND 70 FRI-SAT
AND LOWS FALLING INTO THE 40S OVERNIGHT. THIS WILL ALSO BE GENERALLY
FAVORABLE FOR A DRY FORECAST, BUT THERE DOES REMAIN SOME UNCERTAINTY
FOR FRI NIGHT/SATURDAY AS THE HIGHER RESOLUTION GUIDANCE IS FAVORING
MORE VIGOROUS/CONVECTIVELY ENHANCED ENERGY DAMPENING THE UPPER RIDGE
AND ULTIMATELY PRODUCING SHOWERS FRIDAY NIGHT INTO SATURDAY. IN
PARTICULAR, THE MORE AGGRESSIVE NAM (GFS TO A LESSER EXTENT) IS
KEYING IN ON ENHANCED NORTHWARD MOISTURE TRANSPORT INTO THE LOWER
PENINSULA AFTER THE LOSS OF CONVECTION TO OUR SOUTH LATE ON FRI
EVENING THEREBY ALLOWING ITS MORE AGGRESSIVELY MODELED UPPER WAVE TO
MAKE THE MOST OF A PERIOD OF MODERATE SYSTEM RELATIVE ISENTROPIC
ASCENT. GIVEN THESE SOLUTIONS` DEPENDENCE ON CONVECTIVE EVOLUTION,
CONFIDENCE IS NOT PARTICULARLY HIGH. IN ADDITION, GIVEN THE
UNFAVORABLE NOCTURNAL TIMING FOR WHAT WOULD BE THE STRONGEST
FORCING, GROUND RELATIVE FLOW REMAINING OUT OF THE EAST, AND A
SYNOPTIC SCALE ENVIRONMENT GENERALLY FAVORING DRIER WX, ELECTED TO
LEAN MORE HEAVILY TOWARD A DRY FORECAST FOR THE WEEKEND.

FORECAST UNCERTAINTY INCREASES A GREAT DEAL INTO EARLY NEXT WEEK
WHEN A PAC JET CURRENTLY ENERGY ALONG 40N SOUTH OF THE ALEUTIANS IS
PROGGED TO EVOLVE INTO A CLOSED LOW SOMEWHERE EAST OF THE ROCKY
MOUNTAINS. AT THE SAME TIME, POTENT HIGH-LATITUDE ENERGY SEEN
WRAPPING SOUTHEASTWARD TOWARD THE BERING STRAIGHT THIS AFTERNOON
WILL FOSTER THE DEVELOPMENT OF A SECOND CLOSED LOW JUST UPSTREAM OF
THE ROCKY MOUNTAINS. THE RESULTANT HIGH AMPLITUDE/OMEGA BLOCK TYPE
OF EVOLUTION CENTERED OVER CENTRAL NORTH AMERICA WILL RESULT IN A
BETTER AND MORE FREQUENT CHANCES FOR SHOWERS AND THUNDERSTORMS BY
THE END OF THE LONG TERM PERIOD.

MARINE...

GUSTY WINDS OF 20 TO 25 KNOTS WILL CONTINUE THROUGH THE REST OF THE
AFTERNOON. WINDS WILL DIMINISH IN THE EVENING AS HIGH PRESSURE
BUILDS INTO THE GREAT LAKES TONIGHT. THIS WILL ALLOW THE SMALL CRAFT
ADVISORY TO EXPIRE. A STRONGER HIGH PRESSURE MOVING OUT OF SOUTHERN
CANADA WILL MAINTAIN WEAK NORTHEAST WIND ALONG WITH DRY CONDITIONS
THROUGH THE END OF THE WEEK.

&&

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

&&

$$

AVIATION.....SC
UPDATE.......SC
SHORT TERM...RK
LONG TERM....JVC
MARINE.......RK


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