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 291747
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
147 PM EDT SAT AUG 29 2015

.AVIATION...

SHOWERS WILL BE A HINDRANCE TO AVIATION OPERATIONS FOR THE AFTERNOON
THROUGH THE EVENING. THE PATTERN WILL HAVE LOW END VFR CEILING AND
VISIBILITY WITH JUST A FEW POCKETS OF MVFR VISIBILITY RESTRICTION IN
A HEAVIER SHOWER. THUNDERSTORM POTENTIAL...IF ANY...REMAINS TOO LOW
TO INCLUDE IN THE TERMINAL FORECASTS. MVFR CEILING AND VISIBILITY
WILL THEN BECOME MORE WIDESPREAD OVERNIGHT THROUGH SUNDAY MORNING AS
THE SURFACE WARM FRONT DRIFTS NORTH OF THE INDIANA/OHIO BORDER. A
PERIOD OF IFR SHOULD ALSO BE EXPECTED AROUND SUNRISE BOTH IN TERMS
OF FOG AND STRATUS AT ALL TERMINALS.

FOR DTW... THUNDERSTORM POTENTIAL REMAINS LOW DURING THE AFTERNOON
AND EVENING. CEILING BELOW 5000 FT WILL BE INCONSISTENT EVEN WITHIN
SHOWERS DURING THE AFTERNOON AND THEN FILL IN MORE SOLIDLY DURING
THE EVENING. A STEADY TREND INTO MVFR OVERNIGHT AND INTO IFR TOWARD
SUNRISE IS LIKELY AS A WARM FRONT MOVES INTO THE REGION.

//DTW THRESHOLD PROBABILITIES...

* MEDIUM FOR CEILING 5000 FT OR LESS DURING AFTERNOON AND EVENING...
  HIGH OVERNIGHT THROUGH SUNDAY MORNING.

&&

.PREV DISCUSSION...ISSUED 1113 AM EDT SAT AUG 29 2015

UPDATE...

A WEAKENING MCV EMBEDDED WITHIN THE LARGER SCALE UPPER TROUGH IS
PROPPING UP A PATTERN OF SHOWERS OVER LOWER MICHIGAN HEADING INTO
THE AFTERNOON. A CONVINCING TREND IN WARMING CLOUD TOPS ALONG THE
LEADING EDGE...COMBINED WITH SUBSTANTIAL DRY AIR BELOW 600 MB IN
THE 12Z DTX SOUNDING...SUPPORTS MESOSCALE MODEL SUGGESTIONS OF A
DIMINISHING TREND AS THE RAIN PATTERN MOVES EASTWARD. THIS TREND
IS ONLY SYMPTOMATIC OF THE LEADING BAND OUTRUNNING THE SUPPORT OF
SEVERAL FAVORABLE INGREDIENTS THAT WILL REMAIN IN PLACE THROUGH
THE DAY. THE LARGER SCALE ENTRANCE REGION OF THE UPPER JET AND
UPPER TROUGH AXIS WILL CONTINUE TO SUPPORT LOW TO MID LEVEL
MOISTURE TRANSPORT/THETA-E ADVECTION THROUGH THE DAY OVER LOWER
MICHIGAN. WHILE NOT AS EFFECTIVE DURING THE DAY...THE RESULTING
ISENTROPIC LIFT WILL CONTINUE TO GENERATE ELEVATED INSTABILITY AND
CLUSTERS OF SHOWERS FROM CLOSER TO THE SURFACE WARM FRONT OVER
INDIANA/ILLINOIS NORTHEASTWARD OVER SE MICHIGAN. THIS WILL MAKE
SHOWERS LIKELY MOST AREAS THROUGH THE AFTERNOON AND LEAVE
THUNDERSTORM POTENTIAL LIMITED BY THE LACK OF SURFACE BASED
INSTABILITY DUE TO THE ONGOING CLOUDS AND SHOWERS...AND WHILE THE
SURFACE WARM FRONT REMAINS SOUTH OF THE MICHIGAN BORDER THROUGH
THE DAYTIME HEATING CYCLE. FOR NOW...THE MORNING FORECAST UPDATE
WILL NUDGE POPS INTO THE LIKELY CATEGORY ALL AREAS AND MAINTAIN
THE SUBDUED POSITION ON THUNDERSTORM POTENTIAL.

PREV DISCUSSION...ISSUED 314 AM EDT SAT AUG 29 2015

SHORT TERM...TODAY AND TONIGHT

MERGING UPPER WAVES (NORTHERN MINNESOTA/IOWA) EARLY THIS
MORNING...WITH MAX HEIGHT FALL CENTER/RIGHT ENTRANCE REGION FORCING
OF UPPER LEVEL JET LOOKING TO TRACK THROUGH CENTRAL LOWER
MICHIGAN/LAKE HURON...SUPPORTING HIGHER BASED SHOWER ACTIVITY THIS
MORNING...MAINLY NORTH OF M-59. CONTINUED MOISTURE TRANSPORT THROUGH
THE DAY AND SHEARED OUT UPPER LEVEL PV FILAMENT/500 MB TROUGH AXIS
DRIFTING THROUGH THE AREA WILL SUPPORT CHANCE POPS FARTHER SOUTH
TOWARD THE OHIO BORDER THROUGH TONIGHT AS MAIN MOISTURE AXIS (PW
VALUES 1.5+ INCHES) ALSO FOLDS OVER INTO EAST-WEST ALIGNMENT. TEPID
DIURNAL INSTABILITY PERHAPS LEADING TO AN ISOLATED THUNDERSTORM.
SURFACE RIDGE AXIS RELUCTANT TO BUDGE DURING THE DAY...WITH WEAK
SURFACE TROUGH/WARM FRONT ATTEMPTING TO EXPAND EAST ALONG THE
SOUTHERN MICHIGAN BORDER TONIGHT...PROVIDING FOCUS FOR POSSIBLE
ACTIVITY...WITH MODEST INSTABILITY IN PLACE AS SHOWALTER INDEX
HOVERS AROUND ZERO. CLOUDS EXPECTED TO LIMIT DIURNAL SWING...HOLDING
MAXES IN THE 70S DURING THE DAY...AND LOW TO MID 60S TONIGHT.

LONG TERM...SUNDAY THROUGH FRIDAY

MID LEVEL TROUGH AXIS ANCHORED OVERHEAD SUNDAY MORNING WILL SLOWLY
EXIT TO THE EAST THROUGH THE DAY...THE LEAD EDGE OF THE INBOUND
INCREASING UPPER HEIGHT FIELD LOOMING ACROSS THE PLAINS TAKING A
PROGRESSIVE HOLD LOCALLY OVER THE NEXT 24-36 HOURS.  MOIST RESIDUAL
BOUNDARY LAYER/NEAR SURFACE CONDITIONS IN COMBINATION WITH DAYTIME
HEATING WILL YIELD A WEAKLY UNSTABLE ENVIRONMENT DURING THE DAYLIGHT
PERIOD.  MID LEVEL TROUGH POSITIONING SUGGESTS THERE MAY BE A NARROW
WINDOW FOR SOME RENEWED CONVECTIVE DEVELOPMENT WITHIN THE TRAILING
SHEAR AXIS/CYCLONIC FLOW...ALTHOUGH MOST RECENT MODEL GUIDANCE
TEMPERING THIS RESPONSE PARTICULARLY ACROSS NORTHERN SECTIONS.  WITH
PROJECTED HIGHS /80 DEGREES/ AT THE CUSP OF CONVECTIVE
TEMPERATURES...THIS POINTS TOWARD SIMPLY A LOW END
POTENTIAL/COVERAGE OF SHOWERS AND THUNDERSTORMS FOR SUNDAY.

CONDITIONS THROUGHOUT THE UPCOMING WORK WEEK WILL LARGELY BE DEFINED
BY LIGHT SOUTHWEST LOW LEVEL FLOW TUCKED BENEATH QUASI-STATIONARY
UPPER RIDGING.  THIS PATTERN WILL FAVOR A TRANSITION BACK TOWARD
ABOVE NORMAL WARMTH...WITH DAYTIME READINGS CLIMBING WELL INTO 80S
THROUGH THE WEEK.  LIMITED POTENTIAL FOR CONVECTIVE DEVELOPMENT
THROUGH THIS TIME GIVEN THE ILL-DEFINED/NEGLIGIBLE FORCING AND
WARM MID LEVEL TEMPERATURES. MID RANGE GUIDANCE DOES CENTER AN
OPPORTUNITY ON WEDNESDAY AS A WEAK IMPULSE BRIEFLY WORKS THROUGH
THE EXISTING RIDGE CENTER.

MARINE...

GENERALLY LIGHT WINDS WILL EXIST ACROSS ALL MARINE AREAS THROUGH
THE WEEKEND AS BROAD HIGH PRESSURE REMAINS IN PLACE. A LIGHT
SOUTHWEST WIND WILL CONTINUE INTO EARLY NEXT WEEK WITH HIGH
PRESSURE CENTERED OVER THE EASTERN OHIO VALLEY.

&&

.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.