000
FXUS63 KDTX 152001
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
401 PM EDT SAT JUN 15 2013

.SHORT TERM...THE REST OF TODAY AND TONIGHT

THE UPPER LEVEL PATTERN IS IN THE PROCESS OF DEAMPLIFYING THIS
AFTERNOON WHICH WILL ALLOW MOISTURE INITIALLY HELD UP ON THE
GEOPOTENTIAL RIDGE AXIS TO RELEASE EASTWARD. THIS WILL INITIALLY
OCCUR AS THE OLD MCV FROM YESTERDAYS CONVECTION PASSES TO THE SOUTH
OF THE FORECAST AREA. THE CIRCULATIONS NORTHERN SEMICIRCLE WILL PASS
OVER SOUTHERN SECTIONS OF THE FORECAST AREA PRIOR TO 00Z. LOW LEVEL
DRY AIR REMAINS IN PLACE...WHEN COMBINED WITH MEAGER CONVECTIVE
DEPTH/VIGOR WILL MAKE IT DIFFICULT TO ALLOW MUCH MORE THAN A CHANCE
POTENTIAL FOR LIGHT QPF THIS AFTERNOON.

SHORTWAVE ENERGY THAT IS NOW LIFTING INTO PORTIONS OF IOWA AND
SOUTHERN MINNESOTA WHICH IS RESPONSIBLE FOR THE UPSTREAM
THUNDERSTORM ACTIVITY WILL ROLL OVER ANTICYCLONICALLY AND ARRIVE
OVER SOUTHEASTERN MICHIGAN THE LATTER HALF OF THE NIGHT. THE
BREAKDOWN OF THE RIDGE WILL REALLY GET THINGS MOVING...EVEN
SUPPORTING SOME RIGHT ENTRANCE REGION DYNAMICS OF AN UPPER LEVEL JET
STREAK THAT WILL BE CRESTING THE RIDGE TOP. DEEP COLUMN DEFORMATION
IS SHOWN TO INCREASE SUBSTANTIALLY AFTER 5-6Z TONIGHT. THERE STILL
REMAINS QUITE A BIT OF UNCERTAINTY AS THE MEMBERS OF THE NWP SUITE
ARE ALL OFFERING THERE DIFFERENT FLAVORS FOR THE OVERNIGHT PERIOD.
FROM THIS VANTAGE POINT THERE IS QUITE A BIT OF HESITATION GIVEN TO
THE NAM WHICH IS SHOWING BULK OF THE PRECIPITATION EVENT OCCURRING
THIS EVENING. PREFERENCE HERE IS TO WAIT FOR THE UPPER LEVEL FORCING
AND ADVECTION OF DEEPER THETA E TONIGHT TO CALL FOR THE MAIN
PRECIPITATION WINDOW. NAM IS AGAIN QUESTIONABLE ON
INSTABILITY...SUGGESTING MUCAPES TONIGHT OF SOME 500 TO 1000 J/KG BY
15.12Z. THE GFS SOLUTION IS SHOWING CONSIDERABLY LESS CAPE AT LESS
THAN 500 J/KG. MIDLEVEL LATENT HEATING CONSIDERATIONS SUPPORT THE
LESS/GFS SOLUTION SO STRONG STORMS ARE NOT EXPECTED. HOWEVER...THE
ITEM OF NOTE IS HODOGRAPH LENGTH AND THE AMOUNT OF WESTERLY SHEAR
LATE WITH RETURN OF ZONAL WESTERLIES. A GOOD COMBINATION OF DEEP
MOISTURE AND COLUMN DEFORMATION SUGGESTS A GOOD POTENTIAL FOR
OBSERVED LIQUID...PERHAPS .25 TO .5 INCH BY THE END OF THE PERIOD.

&&

.LONG TERM... SUNDAY THROUGH SATURDAY

RAPID PROGRESSION OF THE UPPER LEVEL JET AXIS WILL CARRY THE
OVERNIGHT PATTERN OF SHOWERS AND THUNDERSTORMS OUT OF SE MICHIGAN
DURING SUNDAY MORNING. THE REGION OF MID LEVEL SUBSIDENCE TRAILING
THE JET AXIS OVER THE NORTHERN PLAINS TODAY IS WELL INITIALIZED IN
THE NEW 12Z MODEL RUNS, JUDGING FROM LAYER RH FIELDS, AND IS SHOWN
TO SETTLE OVER LOWER MICHIGAN DURING SUNDAY AFTERNOON. THIS NORMALLY
LENDS ENOUGH CONFIDENCE TO THE DRYING TREND TO REMOVE POPS WITH THE
PASSAGE OF THE MID LEVEL THETA-E MINIMUM OVER THE AREA. HOWEVER, IN
THIS CASE, EVIDENCE OF STRONG SURFACE BASED INSTABILITY AND LITTLE
OR NO MID LEVEL CAP REMAINS EVIDENT IN MODEL DATA THROUGH SUNDAY
AFTERNOON. MODEL SOUNDINGS INDICATE FAMILIAR QUESTIONS AND
DIFFERENCES IN THE DEPICTION OF BOUNDARY LAYER MOISTURE QUALITY WITH
THE NAM INDICATING DEEPER MOISTURE/SLOWER DRYING COMPARED TO THE
OTHER MODELS, ALTHOUGH ALL HAVE TRENDED TOWARD MAINTAINING SURFACE
DEWPOINT IN THE 60S WELL INTO THE AFTERNOON. THE MAIN CAUSE FOR
CONCERN IS THE LACK OF ANY SUBSTANTIAL SUBSIDENCE INVERSION IN THE
SOUNDINGS THAT WOULD REFLECT EFFECTIVE SUPPRESSION OF CONVECTION
GIVEN SURFACE HEATING IS EXPECTED TO LIFT CAPE UP AROUND 1700 J/KG
BY LATE AFTERNOON. THIS IS ALL SUFFICIENT EVIDENCE FOR A LOW END
CHANCE POP, MAINLY SOUTH OF THE INTERSTATE 69 CORRIDOR, WHERE THE
BEST COMBINATION OF HEATING/DIFFERENTIAL HEATING AND RESIDUAL
SURFACE TROUGHING WILL WORK AGAINST MIXING OF BOUNDARY LAYER
MOISTURE AND MID LEVEL NEGATIVE THETA-E ADVECTION.

A SNEAKY WARM SUNDAY AFTERNOON WILL LEAD TO A MILD BUT DRY SUNDAY
NIGHT AS RETURN FLOW CONSOLIDATES AHEAD OF THE NEXT WAVE OVER THE
NORTHERN GREAT LAKES. THE WAVE WILL SHEAR EASTWARD INTO THE BASE OF
THE LONG WAVE UPPER LOW OVER EASTERN CANADA AND MAINTAIN DEEP ZONAL
WESTERLY FLOW TO THE SOUTH OVER LOWER MICHIGAN. THE ASSOCIATED
SURFACE LOW WILL PULL A RESPECTABLE COLD FRONT FOR THIS TIME OF YEAR
INTO SE MICHIGAN DURING MONDAY AFTERNOON INTO MONDAY EVENING AND
PRESENT THE NEXT BEST CHANCE OF SHOWERS AND STORMS. THE SCENARIO
WILL PRESENT A SOLID COMBINATION OF DAYTIME CONVECTIVE POTENTIAL
WITH GOOD FRONTAL DYNAMICS LINGERING WELL INTO MONDAY NIGHT. TODAY`S
12Z SOLUTIONS INDICATE A BIT LESS TENDENCY FOR THE FRONT TO STALL OR
FOR A WAVE TO DEVELOP BEFORE THE FRONT EXITS LOWER MICHIGAN BY
TUESDAY MORNING. THIS ADDS CONFIDENCE TO A DRY FORECAST FOR TUESDAY
WITH FRESH CANADIAN HIGH PRESSURE BUILDING INTO THE REGION THROUGH
WEDNESDAY THAT WILL PROVIDE IDEAL MID JUNE CONDITIONS. MAX TEMPS ON
THE LOW END OF THE NORMAL RANGE IN THE LOWER 70S WILL BE ACCOMPANIED
BY LOW HUMIDITY THROUGH THE MID WEEK PERIOD.

IT IS EXPECTED THE INFLUENCE OF CANADIAN HIGH PRESSURE WILL LINGER
INTO THE END OF THE WEEK AS WELL. THIS WILL BE MAINLY DUE TO A
MATURE BLOCK IN THE LONG WAVE UPPER AIR PATTERN EVOLVING FROM THE
NORTH PACIFIC INTO WESTERN CANADA THAT WILL MAINTAIN A RIDGE JUST
EAST OF THE ROCKIES AND NORTHWEST FLOW OVER THE GREAT LAKES. ANY
POTENTIAL FOR RAIN WILL BE TIED TO WAVES AND ASSOCIATED SURFACE
FRONTS WITHIN THIS NORTHWEST FLOW. GIVEN THE LOW PREDICTABILITY IN
THE SMALL SCALE AND SLOWLY EVOLVING LARGE SCALE PATTERN PREFER TO
PUSH ANY MEANINGFUL CHANCE OF RAIN OFF UNTIL NEXT SATURDAY.

&&

.MARINE...

FAVORABLE MARINE CONDITIONS WILL PERSIST ACROSS AREA WATERWAYS WITH
A BENIGN PATTERN IN PLACE. SOME DISRUPTION OF MARINE CONDITIONS IS
POSSIBLE TONIGHT DUE TO SHOWERS AND THUNDERSTORMS. WIND AND WAVE
CONDITIONS WILL OTHERWISE REMAIN FAVORABLE PERHAPS THROUGH LATE
MONDAY WHEN THE NEXT COLD FRONT IS DUE THROUGH THE REGION.

&&

.AVIATION...ISSUED 221 PM EDT SAT JUN 15 2013

//DISCUSSION...

THE UPPER LEVEL PATTERN IS IN THE PROCESS OF DEAMPLIFYING THIS
AFTERNOON. WITH WINDS ALOFT BECOMING MORE ZONAL...MOISTURE
ADVECTION WILL OCCUR RATHER QUICKLY MOVING FORWARD. THERE APPEARS
TO BE TWO ROUNDS OF PRECIPITATION POTENTIAL THROUGH TONIGHT. THE
FIRST WILL BE WITH INITIAL WARM AIR AND MOISTURE ADVECTION VERY
LATE THIS AFTERNOON...AFTER 21Z. THE SECOND FAVORABLE TIME PERIOD
WILL BE AFTER 6Z TONIGHT AS CONVECTIVE WAVE AND BETTER UPPER LEVEL
DYNAMICS SLIDE OVERHEAD.

AT DTW...THE NORTH EDGE OF THE OLD MCV WILL SLIDE OVER FAR
SOUTHEASTERN MICHIGAN DURING THE LATE AFTERNOON. THIS ACTIVITY IS
OUTPACING BETTER LOW LEVEL MOISTURE AT THIS TIME. THIS SUGGESTS
THAT PRECIPITATION WILL REMAIN LIGHT WITH VFR CONDITIONS HOLDING.

//DTW THRESHOLD THREATS...

* HIGH CONFIDENCE IN CEILINGS FALLING BELOW 5KFT THIS EVENING.

* LOW CONFIDENCE THAT A THUNDERSTORM WILL IMPACT KDTW AIRSPACE

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.

&&

$$

SHORT TERM...CB
LONG TERM....BT
MARINE.......CB
AVIATION.....CB


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