Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 290755
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
255 AM EST Tue Nov 29 2016

.DISCUSSION...

Dynamically forced convection oriented along the occluded front and
within the corridor of greatest height falls will lift out of the
area to the northeast prior to daybreak. Strong westerly wind field
will provide potential for wind gusts of 40 to 50 mph on an isolated
based on upstream observations so far this morning. Elevated dry
advection surged into the area hours ago and will continue to
descend through the column during the morning. Low-level moisture
axis supporting clouds as far west as Indiana should slowly erode as
clouds work through the southeast half of the CWA and dewpoints fall
into the low 40s by this aftn. Ongoing warm advection pushing 850mb
temps into the mid single digits and better insolation through a
partial coverage of aftn mid-level clouds will support highs in the
mid 50s...perhaps touching 60 in a best case scenario.

Uncertainty increases markedly by Wednesday as the large cyclone to
the west nudges east and an elongated shear max propagating through
the eastern periphery of the trough lifts through the area. Lower
static stability supports potential for deepening low pressure to
foster a blossoming precip shield overhead. SUNY Stony Brook PC
analysis suggests the bulk of variability among the ECMWF ensemble
members is due to intensity outcomes. An ever-so-slightly flatter
00z solution appears to limit PV advection and favor a weaker
solution. This also falls in line with the op GFS and the vast
majority of GEFS members. Although this increases confidence that
Wednesday will not be the washout that some NWP has suggested, there
remains plenty of potential for afternoon shower development. Will
retain the west-east pop gradient on Wednesday but will refrain from
making a call by raising or lowering pops until NWP spread shows
signs of collapsing toward a solution. With no airmass change from
Tuesday, increased clouds and potential for rain suggest max temps
in the low to mid 50s.

Maturing cold conveyor will finally push through the forecast area
Wednesday night as the low is shoved into Quebec by the continued
surge of Pacific jet energy. Moist cyclonic flow and embedded
shortwaves propagating overhead support a chc mention of ra/sn
showers on Thursday, but nothing impactful due to marginal lake
instability and borderline temperatures.

&&

.MARINE...

Ongoing south to southeast gales this morning will ease through the
day as winds become south-southwesterly.  Modest southerly breeze
will hold across all marine areas tonight and Wednesday, maintaining
more favorable wind and wave conditions through this time.  There
will be a period of stronger southwesterly flow Wednesday night and
Thursday as colder air funnels back into the region.  At this time,
gusts are expected to remain below gales.

&&

.PREV DISCUSSION...
Issued at 1158 PM EST Mon Nov 28 2016

AVIATION...

Excruciating mix of VFR to IFR ceilings have existed this evening
with height of widespread precipitation lifting northward through
the cwa. Pockets of moderate rainfall have developed over the past
hour, but back edge of the precipitation and dryslot is already
lifting into the far southern cwa. The NAM remains adamant that
ceiling heights will tank into IFR while the HRRR has backed off
considerably suggesting MVFR. Rolled back mention for
precipitation the remainder of the night based on trends and
shifted to -DZ. Deep, but not particularly strong or active,
subsidence will build into southeastern Michigan for Tuesday.
Potential does exist for some MVFR ceilings with moisture trapped
below inversion, however, clouds Tuesday may be more scattered in
nature.

For DTW...MVFR and IFR conditions have been slow to develop.
With back edge of the rain already lifting into the area, rolled
back the mention and shifted to -DZ. Cold front passage is timed
at DTW around 14Z with a minor change in wind direction from about
190 to 210. VFR cigs to develop by mid morning with return to MVFR
likely Tuesday evening.

//DTW Threshold Probabilities...

* High for ceilings AOB 5000 feet into Tuesday morning.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Gale Warning until 4 PM EST this afternoon FOR LHZ363-421-422-441-
     462.

     Gale Warning until 10 AM EST this morning FOR LHZ361-362-442-443-
     463-464.

Lake St Clair...Small Craft Advisory until 10 AM EST this morning FOR LCZ460.

Michigan waters of Lake Erie...Gale Warning until 7 AM EST this morning FOR LEZ444.

&&

$$

DISCUSSION...JVC
MARINE.......MR
AVIATION.....CB


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at www.weather.gov/detroit.



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