Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KDTX 011844
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
244 PM EDT MON SEP 1 2014

.SHORT TERM...THIS EVENING AND TONIGHT

18Z SPECIAL CONFIRMS THE WARMER COLUMN DEPICTED BY THE RAP AND THEN
SOME. 900MB INVERSION IS QUITE A BIT MORE ROBUST THAN DEPICTED BY
THE GUIDANCE AS IS THE 600MB CAP. THUS, EVEN THE MOST TAME
DEPICTIONS OF CONVECTION IN THE NWP ARE LIKELY TOO AGGRESSIVE AND
CONCERNS REGARDING CAPPING NOTED IN THE MORNING UPDATE ARE
CONFIRMED. UPDRAFTS WILL STRUGGLE ACROSS MOST OF THE CWA WITH THE
EXCEPTION OF LOCATIONS NORTH OF I-69 AND ESPECIALLY WEST OF US-23
WHERE MID-LEVEL COOLING AND FORCING WILL BE MAXIMIZED. WITH THE LINE
ALREADY MARCHING TOWARD THIS AREA, EXPECT THAT THE ABUNDANCE OF
MID-LEVEL DRY AIR AND UNIDIRECTIONAL FLOW ABOVE 1.5KM WILL SUPPORT
BOWING SEGMENTS CARRYING A LOW-END SEVERE WIND THREAT. IN ADDITION,
ISOLATED TORNADO THREAT OUTLINED IN THE EARLIER UPDATE REMAINS IN
TACT. FOR REMAINING AREAS, EXPECT NOTHING MORE THAN A GUST TO 40
MPH. IN ADDITION, BACKED OFF ON POPS AS EARLIER SUSPICIONS REGARDING
COVERAGE POTENTIAL STILL LOOM.

A WEAK COLD FRONT WILL SAG THROUGH THE AREA TONIGHT. FRONTAL
INVERSION WILL PROMOTE EXPANSION OF STRATUS LATE TONIGHT, BUT EXPECT
THAT MOISTURE WILL BE TOO SHALLOW AND FORCING TOO WEAK TO SUPPORT
ANY LEGITIMATE COVERAGE OR INTENSITY OF SHOWERS. WITH UPPER SUPPORT
IN THE FORM OF A SHEARING SHORTWAVE NOT SCHEDULED TO ARRIVE UNTIL
TUESDAY MORNING PER 12Z GUIDANCE, AND MAINLY SOUTH OF THE AREA AT
THAT, NOTHING MORE THAN A CHC POP IS WARRANTED ATTM.

&&

.LONG TERM...TUESDAY THROUGH NEXT MONDAY

A COLD FRONT WILL BE SOUTHEAST OF THE CWA TO START OUT TUESDAY
MORNING. HOWEVER A MID LEVEL SHORTWAVE RIDING NORTHEAST ALONG THE
FRONT WILL BRING THE CHANCE FOR SHOWERS AND THUNDERSTORMS TO THE
AREA TUESDAY MORNING. AFTER THE SHORTWAVE TRACKS OFF TO THE
NORTHEAST SIGNIFICANT DRYING WILL TAKE PLACE AS A SLUG OF 30 PERCENT
RELATIVE HUMIDITY AT 700 MB ADVECTS IN FROM THE WEST...ENDING RAIN
CHANCES QUICKLY EARLY TUESDAY AFTERNOON. WHILE THERE IS STILL SOME
UNCERTAINTY REGARDING HOW FAR WEST THE RAIN WILL FALL GIVEN THE PUSH
OF DRY AIR ADVECTING IN...THE LATEST SUITE OF MODELS HAS THE DRIER
AIR PUSHING IN A BIT SOONER THAN THE 00Z RUNS. THEREFORE WILL NUDGE
THE FORECAST A BIT DRIER TUESDAY AFTERNOON FROM THE PREVIOUS
FORECAST. DESPITE THE PASSAGE OF A COLD FRONT THERE ISN`T A LARGE
PUSH OF COLD AIR ASSOCIATED WITH IT...MEANING DAYTIME HIGHS ARE
EXPECTED TO GET AROUND 80 TUESDAY AFTERNOON BEHIND THE FRONT.
RIDGING WILL KEEP THE FORECAST DRY THROUGH WEDNESDAY AS REBOUNDING
HEIGHTS ALLOW DAYTIME HIGHS TO GET BACK INTO THE LOWER 80S BY
WEDNESDAY AFTERNOON.

MOISTURE SURGE FROM THE GULF OF MEXICO COMMENCES ON THURSDAY AS A
LOW CHANCE FOR CONVECTION EXISTS WITHIN THE WARM SECTOR OF A
REGION-WIDE LOW PRESSURE SYSTEM. BEST CHANCE FOR THUNDERSTORMS
/POSSIBLY SEVERE/ WILL BE FRIDAY AS WARM AND MOIST AIRMASS (85/70
T/TD) IS IN PLACE ALONG WITH FORECASTED CAPE OF 3000 J/KG. BULK
SHEAR INCREASES TO NEAR 30 KT IN THE 1-6 KM LAYER AS WELL. THESE
INGREDIENTS WILL BE IN PLACE AS A RAGGED COLD FRONT CROSSES THE
STATE. THIS BRINGS A TRIPLE THREAT OF SEVERE WEATHER WITH
WIND...HAIL...AND ISOLATED TORNADOES ALL POSSIBLE

&&

.MARINE...

SHOWERS AND THUNDERSTORMS WILL TRACK THROUGH THE CENTRAL GREAT LAKES
TONIGHT AS A COLD FRONT MOVES THROUGH LAKE HURON AND LOWER MICHIGAN.
SOME OF THESE STORMS MAY BE SEVERE...MAINLY ACROSS THE NORTHERN
PORTION OF LAKE HURON. HIGH PRESSURE WILL BUILD INTO THE REGION
BEHIND THIS FRONT ON TUESDAY...WHICH WILL REMAIN IN CONTROL OF THE
WEATHER THROUGH THURSDAY...PROVIDING FAVORABLE BOATING CONDITIONS.

&&

.AVIATION...ISSUED 114 PM EDT MON SEP 1 2014

//DISCUSSION...

LOW STRATUS CONTINUES TO MIX UP TO LOW VFR DIURNALLY FORCED CU.
EXPECT THIS TREND TO CONTINUE THROUGH THE NEAR TERM. ATTENTION
THEN TURNS TOWARD TSTORM CHANCES THIS AFTERNOON. CAPPING WILL
LIMIT POTENTIAL SOUTH OF KPTK SO TSHRA WAS REMOVED FOR THESE
LOCATIONS AS THE PROBABILITY IS NOW TOO LOW TO WARRANT A MENTION
IN THE TAFS. EXPECTATIONS REMAIN UNCHANGED FROM KFNT NORTH
UPSTREAM ACTIVITY IS MORE CERTAIN TO MOVE IN THIS AFTERNOON. LOW CLOUDS AND
PERHAPS A VISIBILITY RESTRICTION WILL BE POSSIBLE BEHIND THE FRONT
LATE TONIGHT BUT ONCE AGAIN EXPECT PRECIP POTENTIAL TO REMAIN
RATHER LOW WITH THE BULK OF 12Z GUIDANCE HOLDING ACTIVITY SOUTH OF
THE MICHIGAN BORDER.

FOR DTW...ALTHOUGH CONFIDENCE IN TSTORMS HAS DECREASED...IT AT LEAST
REMAINS PLAUSIBLE. THE BEST TIME FOR A THUNDERSTORM TO IMPACT THE
AIRPORT WILL BE 21Z-23Z THIS AFTERNOON. CONFIDENCE IN SHOWER
COVERAGE TOWARD MORNING IS ALSO QUITE LOW. ELECTED TO ELIMINATE
SPECIFIC MENTION FROM THE TAF UNTIL POTENTIALLY IMPACTED AREA BECOMES
MORE CLEAR.

//DTW THRESHOLD THREATS...

* MEDIUM CONFIDENCE IN CEILINGS BELOW 5KFT THIS AFTERNOON AND LATE TONIGHT

* LOW CONFIDENCE THAT A TSTORM WILL IMPACT KDTW

&&

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

&&

$$

SHORT TERM...JVC
LONG TERM....KURIMSKI/MM
MARINE.......KURIMSKI
AVIATION.....JVC


YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.