Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

Home | Current Version | Previous Version | Graphics & Text | 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 301717
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
117 PM EDT SUN AUG 30 2015

.AVIATION...

STUBBORN MVFR CEILING...MOSTLY FROM PTK NORTHWARD...IS ASSOCIATED
WITH A FILLING WARM FRONT/TROUGH THAT IS MOVING SLOWLY EASTWARD
DURING THE AFTERNOON. THE DEPARTURE OF THE FRONTAL REMNANTS WILL
ALLOW LOW END VFR CEILING TO DEVELOP AT ALL LOCATIONS AS SURFACE
HEATING HELPS LIFT THE CLOUD BASE. THAT WILL LEAVE COVERAGE OF
SHOWERS OR ISOLATED THUNDERSTORMS TO BE MONITORED THROUGH MID
EVENING. EXPECTATION REMAINS THAT COVERAGE WILL BE TOO LOW TO
PINPOINT AT A TERMINAL LOCATION DEFERRING TO LATER UPDATES AS RADAR
TRENDS BECOME MORE CLEAR. DIMINISHING CLOUDS DURING THE EVENING WILL
LIKELY LEAD TO FOG AGAIN LATE TONIGHT. THERE WAS QUITE A BIT OF
IFR/LIFR COVERAGE OVER WISCONSIN/IOWA/ILLINOIS TO GUIDE POTENTIAL AS
THE NORTHERN FRINGES OF HIGH PRESSURE SETTLES OVER SE MICHIGAN
THROUGH MONDAY MORNING.

FOR DTW... LINGERING WARMTH AND HUMIDITY WILL PROMOTE LIFTING AND
PERSISTENCE OF CEILING AROUND 4500 FT THROUGH THE AFTERNOON FOLLOWED
BY A GRADUAL CLEARING TREND DURING THE EVENING. CLEAR SKY AND LIGHT
WIND WILL MAKE IFR FOG LIKELY AROUND SUNRISE MONDAY.

//DTW THRESHOLD PROBABILITIES...

* HIGH FOR CEILING 5000 FT OR LESS DURING THE AFTERNOON.

&&

.PREV DISCUSSION...ISSUED 1123 AM EDT SUN AUG 30 2015

UPDATE...

HELD THE LINE FROM THE MORNING FORECAST PACKAGE ON THUNDERSTORM
POTENTIAL FOR THIS AFTERNOON. THE SUBDUED/ISOLATED MENTION REMAINS
ON TARGET MAINLY AS DAYTIME HEATING ACTS ON LINGERING LOW LEVEL
MOISTURE. THE 12Z DTX SOUNDING INDICATES THE BEGINNING OF CAP
DEVELOPMENT UNDER INFLUENCE OF SUBSIDENCE TRAILING THE UPPER LEVEL
TROUGH AXIS AS IT EXITS LOWER MICHIGAN. THE RACE IS ALSO ON
BETWEEN SURFACE HEATING AND NEGATIVE THETA-E ADVECTION AROUND 850
MB. THIS PROCESS WILL GRADUALLY REDUCE THE DEPTH OF MOISTURE
INDICATED IN THE SOUNDING. MAINTENANCE OF ISOLATED THUNDERSTORM
COVERAGE ALONG AND SOUTH OF INTERSTATE 69 IS THEN A NOD TO CONTINUED
DEPICTION OF DEVELOPMENT IN EVEN THE MOST RECENT MESOSCALE MODEL
RUNS. THE LATEST RAP SUGGESTS SURFACE BASED CAPE RISING TO ABOUT
1200 J/KG AS LONG AS DEWPOINT CAN HOLD IN THE MID 60S. CONVECTION
MAY END UP BEING MORE OF A MODERATE DEPTH SHOWER RATHER THAN A
THUNDERSTORM ASSUMING MID LEVEL SUBSIDENCE CONTINUES TO EVOLVE. IF
CONVECTION CAN BREACH THE WARM LAYER AND REACH -20C/THUNDER THEN
SOME POTENTIAL FOR PRECIP LOADED WIND GUSTS WILL EXIST DUE TO
ENTRAINMENT OF MID TO UPPER LEVEL DRY AIR INDICATED IN THE
SOUNDING AND WV IMAGERY. OTHERWISE...JUST A LOCALLY HEAVY DOWNPOUR
EXPECTED THROUGH THE PEAK HEATING CYCLE INTO EARLY EVENING.

PREV DISCUSSION...ISSUED 302 AM EDT SUN AUG 30 2015

SHORT TERM... TODAY AND TONIGHT

MOIST AIRMASS IN PLACE OVER SOUTHEAST MICHIGAN EARLY THIS
MORNING...AS 00Z DTX SOUNDING REVEALED A 700 MB DEW PT OF 4
C...850 MB DEW PT OF 12 C...ALONG WITH A PW VALUE OF 1.6 INCHES.

SHEARED OUT SHORTWAVE/PV WILL SLOWLY BE EXITING THE CENTRAL GREAT
LAKES...BUT LAST VESTIGE OF 850-700 MB THETA-E AXIS STILL PROVE
SUFFICIENT FOR ISOLATED-SCATTERED LIGHT SHOWERS THIS MORNING BEFORE
DRIER AIR ATTEMPTS TO SLOWLY FILTER INTO SOUTHERN LOWER MICHIGAN
THROUGH THE DAY...BUT UNCERTAIN WE WILL BE ABLE TO SCOUR OUT THE LOW
LEVEL MOISTURE...AS 00Z NAM MAINTAINS HIGHER RH VALUES IN THE 925-
850 MB LAYER. WITH 500 MB TEMPS FALLING UP TO 2 C DEGREES...SURFACE
BASED INSTABILITY/CAPE IS PROGGED TO RISE TO AROUND 750 J/G...PER
00Z GFS...BUT 1000-2000 J/KG PER 00Z NAM...AS SURFACE DEW PTS REMAIN
SOLIDLY IN THE 60S. HOWEVER...700 MB TEMPS WILL BE RISING TO AROUND
9 C NORTH OF I-69...WHICH SHOULD ULTIMATELY PROVIDE A SUFFICIENT
CAP. SOUTH OF I-69 IS WHERE COOLER MID LEVELS PERSIST LONGER AND
WHERE A SLIGHT/LOW CHANCE OF SHOWERS/THUNDERSTORMS WILL BE CARRIED
FOR THE AFTERNOON HOURS. MINIMAL CONCERNS FOR SEVERE WEATHER WITH
WEAK WIND FIELDS...IF IN FACT A CELL IS EVEN ABLE TO GO UP.

BASED ON PESKY CLOUDS EXPECTED TODAY...WILL HOLD MAXES AROUND 80
DEGREES...BUT POTENTIAL FOR WARMER TEMPS IS THERE WITH 850 MB TEMPS
OF 16 C. LOW LEVEL MOISTURE/ELEVATED DEW PTS HOLDING IN THE LOWER
60S TONIGHT SHOULD SET THE STAGE FOR SOME FOG AS SKIES BECOME MAINLY
CLEAR WITH LIGHT/CALM WINDS IN PLACE.

LONG TERM...MONDAY THROUGH SATURDAY

SOUTHERN PLAINS UPPER RIDGE WILL UNDERGO STEADY DOWNSTREAM
AMPLIFICATION OVER THE NEXT 48 HOURS...IN RESPONSE TO SUBSTANTIAL
HEIGHT FALLS WORKING INTO THE WESTERN CONUS.  THIS PROCESS WILL
EFFECTIVELY CENTER AN UPPER LEVEL ANTICYCLONE OVER SE MICHIGAN BY
MONDAY.  A HIGH DEGREE OF STABILITY UNDER THE ATTENDANT MINIMUM IN
THETA-E AND AN ELEVATED MID LEVEL TEMPERATURE PROFILE WILL YIELD
PLENTY OF SUNSHINE...AND NO REAL OPPORTUNITY FOR CONVECTIVE
DEVELOPMENT.  THE INCREASE IN THICKNESSES AND GENERALLY LIGHT
SOUTHWEST FLOW WILL PROVIDE A NOTED UPTICK IN TEMPERATURES RELATIVE
TO TODAY...WITH DAYTIME READINGS REACHING THE MID 80S.

UPPER RIDGING TO REMAIN THE PRIMARY GOVERNING FEATURE THROUGH THE
REMAINDER OF THE UPCOMING WORK WEEK.  THIS WILL TRANSLATE INTO A
RELATIVELY BENIGN STRETCH OF WEATHER CONDITIONS...WITH ABOVE NORMAL
WARMTH AND LIMITED /IF ANY/ POTENTIAL FOR CONVECTION.  THE RIDGE
AXIS MAY LOSE SOME DEFINITION BY MIDWEEK AS A WEAK HEIGHT FALL
CENTER DRIFTS THROUGH THE OHIO VALLEY...WITH A CORRESPONDING GRADUAL
INCREASE IN THETA-E DURING THIS TIME.  PLAUSIBLE SCENARIO THAT WEAK
CVA WORKING THROUGH ALONG THE NORTH END OF THIS FEATURE PROVIDES A
LOCALIZED/BRIEF WINDOW FOR ASCENT...MEDIUM RANGE GUIDANCE STILL
CENTERING ON WEDNESDAY.  LOW END POTENTIAL AT THIS STAGE GIVEN AN
OTHERWISE LACKLUSTER LOOKING FORCING/WIND FIELD.

MARINE...

BENIGN MARINE WEATHER WILL CONTINUE ACROSS THE GREAT LAKES REGION
THROUGH MUCH OF THE UPCOMING WEEK. A STRONG RIDGE OF UPPER LEVEL
HIGH PRESSURE WILL MAINTAIN LIGHT FLOW AND A GENERAL SOUTHWEST WIND
DIRECTION.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

AVIATION.....BT
UPDATE.......BT
SHORT TERM...SF
LONG TERM....MR
MARINE.......MR


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.