Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 131701

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1201 PM EST Tue Feb 13 2018


Dry airmass in place with surface ridge extending from strong
departing high pressure will hold through the daylight hours with
just mid/high clouds around. Low level moisture advection this
evening may support an MVFR deck of clouds across southern TAF sites
by Midnight. These low clouds are currently observed along the Ohio
River, but confidence is still not high they will survive the entire
trip northward. Winds shifting to the southwest late tonight will
likely push the clouds to the east by sunrise, even if they do make
inroads into the State. Otherwise, warm advection southwest flow
tomorrow will lead to steepening low level inversion, which brings a
low risk of low clouds, but models likely showing snowpack bias and
too cold and moist in the boundary layer.


* Moderate for ceiling 5000 ft 4-8Z tonight, low after.


Issued at 311 AM EST Tue Feb 13 2018


The week ahead will be characterized by the occasional shearing of
energy from the southwest US closed low along the periphery of the
broad, flat upper ridge anchored over the southeast US. Resident
thermal field during this time will be mild, characterized by 850mb
temps rising toward 0C today and remaining in the single digits
until late this week. Surface temps will likewise be on the warmer
side of normal, particularly given emerging southwest return flow
around this morning`s departing Canadian high. As such, today`s
chilly start will rebound moderately toward 30 degrees by late this
aftn , the response ultimately tempered by the delay in warm
advection and incoming mid/high cloud noted on satellite over the
northern Great Plains and Upper MS Valley. The first in the
aforementioned series waves will transit the region late tonight
through Wednesday. The corresponding response in the momentum field
will either hold temperatures steady tonight or force them to rise
back into the upper 20s after a potential late eve/early night drop
prior to more concerted uptick in PGF. Further upstream, the expanse
of low clouds noted over TX/OK this morning will continue to lift
toward the Lower Pensinula, arriving by late Wednesday. Highs
solidly in the 40s, there is high confidence that precip will take
the form of weakly forced rain showers or drizzle by late Wed,
though the near-surface moisture signal from the usual suspects in
the model suite is likely too aggressive owing to the erroneous
snapping the temperature to the dewpoint over melting snowpack.
Arrival of the next wave in the sequence on Thursday will force
another modest jump in temps and moisture and renewed rain
shower/drizzle threat for Thursday. Some potential for a mixed ptype
by Thursday night as a progressive height fall corridor associated
with a more robust northern stream wave ushers in colder air as
moisture axis exits east.


Favorable marine conditions in terms of wind and waves will continue
through mid week as high pressure exits eastward and mild south wind
develops over the Great Lakes. The mild air will produce very high
stability over marine areas which will limit wind gusts to less than
25 knots and limit wave growth on what little open water remains on
Lake Huron. Fog and drizzle will also increase steadily Wednesday
into Thursday as higher dewpoint air flows over snow and ice cover.
Mostly rain is expected Thursday mixing with and changing to snow as
the next cold front moves through the region. Early projections
indicate wind near gales for a short time in the northwest flow
behind the front Friday morning.


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



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