Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 260352

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1152 PM EDT TUE OCT 25 2016


Low level winds will weaken as they veer easterly during the
morning. This should largely hold the lake strato cu (based in the
3500 to 5000 ft range) close to the shores of Lake Huron and Saginaw
Bay. Light rain will then overspread the region from Southwest to
northeast from late morning into the afternoon. Ceilings will trend
downward during the afternoon under the persistent light rain.

For DTW...There remains at least a low chance that some low clouds
may duct off Lake Huron and brush metro Detroit in the 08 to 11Z
time frame before the flow turns more easterly. There will be a
better chance of a sub 5k ft cloud layer later in the morning as the
winds veer toward the southeast, resulting in a trajectory off Lake
Erie. These clouds will expand during the course of the day as a
region of widespread light rain slowly overspreads the area from
southwest to northeast.

//DTW Threshold Probabilities...

*  Low in ceilings below 5000 ft tonight through daybreak Wednesday.
   Moderate late Wednesday morning through afternoon. High Wed night.


Issued at 928 PM EDT Tue OCT 25 2016


There has been some redevelopment of clouds across the northern
Thumb and portions of the Saginaw Valley this evening. The 00Z DTX
showed a deep inversion based near 840mb. Steep lapse rates below
the inversion with nocturnal decoupling in the boundary layer will
allow some continued ducting of the lake clouds into Se Mi. The
low level flow will however veer to the east overnight and will
weaken. This will likely suppress the distance the lake clouds
will be able to move inland overnight. So while high clouds are
temporarily decreasing over the area, the occasional low clouds
off Lake Huron across the north will support an update to the
forecast to nudge sky cover up a little.

Issued at 346 PM EDT Tue OCT 25 2016

Weak shortwave energy emerging over the front range of the Rockies
this afternoon will encounter a weak static stability environment
favorable for a self-deepening scenario driven by latent heat
release over the Lower Missouri and Upper MS River Valleys tonight.
Strong deep layer isentropic ascent will overspread the area late
Wednesday morning through the afternoon as the surface low
translates from eastern Nebraska to north-central Illinois.
Development overcast skies from south to north will be followed by
widespread virga as precipitation works to overcome dry air
reinforced by stout easterly flow. Expect a band of rain to lift
from south during the late morning through the early afternoon in
advance of stronger forcing.

Noteworthy model spread exists with regard to the position of the
surface low by Wednesday evening. This appears to be due, initially,
to tonight`s convection pulling the height falls in the higher
resolution runs further north while synoptic-scale forcing dominates
the low track in the global models. As strong isentropic ascent
ramps up within the classic right entrance region over SE Michigan
and system relative fgen becomes increasingly focused in the lower
portion of the troposphere, the exact position of the attendant warm
front will be important as it will largely dictate how wet/dry our
southern counties are during Wednesday afternoon. Trailing energy
currently over the Pacific Northwest coast at 18z this afternoon is
initialized reasonably well by the GFS and especially the ECMWF -
which made a strong move toward the 12z GFS in allowing the energy
to make a faster entrance into the Great Lakes, forcing the surface
low toward a more northeasterly track by late Wednesday night into
Thursday morning. It is worth noting that the GFS/EC now handle the
timing of this energy in quite similar fashion, but the low track of
the EC seems unexpectedly further south. The forecast is largely
biased toward GFS solution which is essentially a suppressed version
of the convective response observed in the high res along with a
dynamically (and climatologically) preferred track toward the tip of
Lake Erie. Widespread stratiform rain can be expected by late Wed
evening into the overnight period to go along with strong east winds
gusting toward 20 kts and temperatures in the mid 40s falling as low
as the upper 30s. Cyclonic flow and lingering moisture within the
thermal trough will ensure skies remain cloudy after lingering
precip departs early Thursday. Highs will struggle out of the mid
40s Thurs as h85 temps stay solidly in the negative single digits
beneath plenty of clouds.

A broad area of high pressure situated over the eastern half of the
US will bring dry conditions to our area throughout Friday
afternoon. The next chance for rain will enter Friday night into
Saturday, mainly north of I-69, as low pressure travels eastward
across Ontario. Additional chances for precipitation will return on
Sunday as a second low from the Great Plains pushes over MI
throughout the day. Confidence for the early half of next week is
increasing regarding a possible warming trend. A broad area of high
pressure centered over the western Atlantic and low pressure
situated over the northern Great Plains will allow S/SW winds to
usher in warmer temperatures, with 850 mb temps sitting at 14C in
the GFS and 8C in the ECMWF models at 18Z. Temperatures returning
into the 60s will not be out of the question Monday - Tuesday.


Northwesterly flow will continue to decrease through the remainder
of the afternoon and evening as high pressure slides over the
region. Current small craft advisories in effect for Lake Huron
nearshore zones will be cancelled as decreased winds have allowed
wave heights to subside below criteria. Wind will turn easterly
Wednesday as we reside on the north side of a warm front that will
lift into the northern Ohio Valley. The associated low will then
track east along the front Wednesday night. The easterly winds will
increase through the day tomorrow peaking Wednesday night and
Thursday before turning northerly Thursday evening. Winds are
currently expected to remain below gale force but will likely
necessitate small craft advisories once again as winds gust to 25 to
30 knots.


A low pressure system developing over the central Plains will track
through the northern Ohio Valley Wednesday night, resulting in a
widespread rainfall event locally Wednesday through Thursday. The
heaviest rainfall will occur late Wednesday into Wednesday night
before tapering off Thursday. This system will result in a broad
area of rainfall with amounts around three quarters of an inch
through expected.


Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.



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