Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 180809
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
309 AM EST Sat Feb 18 2017

.DISCUSSION...

A spring-like weekend is in the offing for Southeast Michigan. As of
08Z this morning, the sfc warm front was approaching the thumb
region. Temps to the southwest of the front are already in the upper
40s and low 50s. The warm front will clear the forecast area early
this morning. Sfc low pressure tracking across nrn Ontario will drag
a weak cold front into nrn Mi today, which will largely remain
northwest of the Saginaw valley. The degree of low to mid level warm
air now advecting across srn Lower Mi is quite impressive for
February (925mb temps around +15C and 850mb temps around +12C, both
records for DTX upper air climatology on this date). While the core
of warmest low level air will slide southeast of the area this
morning, daytime mixing will still support mild and breezy
conditions today. Aside from the nrn Saginaw Valley and thumb
region, afternoon temps should easily surpass 60 (some mid 60
readings seam possible in Metro Detroit and points south). The
abundance of dry air and mid level confluent flow overhead will
support ample sunshine today. Clear skies tonight will support some
degree of decoupling in the boundary layer. This will offset the
gradient enough to allow min temps to drop into the 30s (actually
near seasonal average daily highs).

Mid level ridge amplification will occur across the upper midwest
into the Great Lakes region Sunday into Monday as mid level
troughing overspreads the srn and cntl Rockies. This will support
strengthening sfc high pressure from nrn Ontario into the ern Great
Lakes by Monday, forcing a lake modified sfc cold front to be forced
across Lake Huron on Sunday and across Se Mi Sunday night. This
front will actually work into the thumb region on Sunday, supporting
much cooler temps. Highs may still make a run at 60 across Metro
Detroit prior to the arrival of this back door cold front. Building
mid level heights will sustain dry weather on Sunday, although mid
and high clouds may be more prevalent. The mid level ridge will be
overhead on Monday, supporting another dry day. Low level easterly
flow off the lakes will however support cooler readings compared to
this weekend (40s and 50s)

Mid level short wave energy is forecast to eject out of the central
Rockies and traverse lower Mi on Tuesday, bringing the next chance
for rain. This system will be followed by another surge of mild air
promising to hold temps well above normal through the end of the
week. The medium range model suite are suggesting the development of
a strong storm system over the upper Midwest and Great Lakes Friday
into Saturday. This will be one to watch over the next several days
and has the potential to bring rain and windy conditions to the
area, with a return of colder air in its wake.

&&

.CLIMATE...

Record highs for today, Feb 18th are as follows: DTW 62 (1976);
FNT 56 (2011); MBS 53 (1981). These are all likely to be broken.
Record high temps for Sunday, Feb 19th are: DTW 64 (1884); FNT 59
(1994); MBS 57 (1930). Sunday highs may come close to these records.

&&

.MARINE...

Moderate westerly flow will persist through late tonight before
turning light northerly as high pressure builds in from the west by
the end of the weekend. Wind gusts below 25 kts over most areas
throughout this time.

&&

.PREV DISCUSSION...
Issued at 1157 PM EST Fri Feb 17 2017

AVIATION...

The surface warm front is on the way through Lower Michigan during
the early morning. The passage of the front will be marked by
veering wind to the southwest with a modest increase in speed.
Temperatures rising back into the 40s will be met with dewpoint
rising into the mid 30s as well which still could produce some MVFR
fog or haze while flowing over the cold ground. Otherwise, only a
few patches of high clouds are associated with the front. Assuming
the warm sector remains decoupled, then low level wind shear will be
associated with faster flow above the surface based inversion
reaching around 40 kts at the top of the shear layer. This will lead
to breezy conditions by afternoon as boundary layer growth builds
into the faster wind aloft. Gusts around 20 knots are reachable
across the area based on upstream observations from Friday afternoon
and considering the low level jet will be weakening through the
morning.

//DTW THRESHOLD PROBABILITIES...

* None.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

DISCUSSION...SC
CLIMATE......SC
MARINE.......JVC
AVIATION.....BT


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