Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 131734
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1234 PM EST Mon Feb 13 2017

.AVIATION...

Existence of weak surface ridging within a warming and dry low level
environment will continue to favor plenty of clear sky across the
lowest 10k ft late today into tonight.  Moderate northwest flow
early this afternoon will ease while backing with time through the
early evening period.  Weak mid level wave lifting across northern
lower Mi overnight may result in some increase in higher level cloud
/mainly MBS/ Tuesday morning.  Development of lower stratus will
likely await the arrival of a stronger push of colder air later in
the day.

For DTW...Brief window thru late afternoon for winds to hover near
crosswind thresholds out of the northwest, but with the flow
expected to back through the afternoon the duration will remain
limited.

//DTW THRESHOLD PROBABILITIES...

* None

&&

.PREV DISCUSSION...
Issued at 305 AM EST Mon Feb 13 2017

DISCUSSION...

Once last wind pop (37-40 knots) occurred around Midnight across the
southern half of the cwa, but cold advection has been tapped out and
winds are diminishing quickly as surface high over the western Ohio
Valley slides East.

Back edge of low clouds already have made inroads into southeast
Michigan early this morning. Continued erosion and eastward
progression expected as inversion heights lower further with upper
level ridge axis moving overhead. With the good deal of sunshine
developing during the day, temperatures rising to around 40/lower
40s, in line with guidance and 925 mb temps warning toward -1 C.

Continued low level warm advection this evening and tonight, but
there is room for winds to attempt to decouple in the evening before
the low level jet (40 knots at 925 mb) arrives overnight. Still,
with some possible transient mid clouds around, thinking upper 20s
to around 30 degrees for mins should hold.

Highly amplified upper level ridge along the west coast of North
America building into the Rockies Tuesday-Wednesday, allowing for
another strengthening upper wave coming out of the Yukon
Territory/Northwest Territories, with the 700 MB cold core of -20 to
-22 C arriving Tuesday night over Lower Michigan, just slightly
colder than last nights system which moved through. Lean moisture to
work with, with 850-700 mb specific humidity around 1.5 g/KG. None-
the-less, pretty good 925-700 mb lapse rates of 7-7.5 C/KM, per 00z
NAM, worthy of scattered snow showers. Cold cyclonic flow on
Wednesday with 850 mb temps in the mid negative teens will support
at least clouds, with flurries or isolated light snow showers likely
around into the Evening hours.

Big warm up then expected to end the work week into the Weekend, as
previously mentioned upper level ridge over the Rockies moves into
the Great Lakes region by Saturday morning. Good low level southwest
flow developing, with the 00z Euro indicating 925 mb temps up to 9 C
Saturday afternoon, which would support high temps well into the
50s, potentially 60 degrees. Still, more conservative approach will
be taken at this time (lower 50s), as fog/low cloud development is a
concern. Surface dew pts forecasted to rise above 40 degrees by end
of the day on Saturday, with 3-5 C dew pts at 925 MB. Continued mild
on Sunday as 1000-500 mb thicknesses still progged to reside around
555 DAM.

MARINE...

Ridge of high pressure off of mid Mississippi River Valley surface
high pressure system will build aggressively through the central
Great Lakes today. Surface winds in the wake of yesterdays cold
front have been diminishing rapidly the past couple of hours. Will
cancel the Gale Warning that had been in effect for Lake Huron.
Northwest to west winds today will be modest, averaging in the 10 to
20 knot range. The next surface low pressure system will drop
straight south southeastward from west of Hudson Bay this afternoon
to eventually the vicinity of Georgian Bay and Lake Ontario by
Wednesday morning. This particularly low pressure system will remain
relatively weak during the next 48 to 60 hours before an eventual
merger with a Noreaster by the latter half of the week.

There are a couple of marine periods to focus on. The first period to
watch for will be winds to increase again this evening as gradient
southwesterly flow increases very rapidly in response to this low
pressure system. Neutral stability conditions will exist for brief
time this evening with solid 25 knot flow over much of Lake Huron.
Stability is then forecasted to increase later tonight and into
Tuesday as warm advection increases. The event to focus on for this
system will be the cold advection that will blast into the region
Tuesday evening and early Wednesday morning. The overall dynamical
support for a cold front is excellent and at this vantage point
model data appears to be behind the curve. Given the overall setup
future gale headlines appear likely for at least Lake Huron.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Gale Watch from late Tuesday night through Wednesday afternoon FOR
     LHZ361>363-421-441-442-462-463.

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

$$

AVIATION.....MR
DISCUSSION...SF
MARINE.......CB

You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.



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