Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 231004
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
604 AM EDT Sun Apr 23 2017
The persistent ridge of high pressure will hold over southern MI
through the afternoon. Strong subsidence and deep dry layer will
keep skies clear through most of the period. Winds will be weak and
westerly until a cold front drops through SE MI this evening (MBS)
and overnight (Detroit area) switching winds from westerly to
northeasterly. A few clouds may arrive with the front but the very
dry resident airmass will likely prevail, keeping skies clear.
//DTW THRESHOLD PROBABILITIES...
Issued at 355 AM EDT Sun Apr 23 2017
Deep midlevel trough and dynamic shortwave energy is now pivoting
through much of western Ontario this morning. Cold air advection was
already well underway last evening with 23.00Z raob out of Pickle
Lake, ON reporting an 850mb temperature down to -13C. This system
has effectively laid out a zonal cold frontal boundary across the
northern shore of Lake Superior. Been monitoring surface
observations in and around Lake Superior and it appears the surface
boundary has pushed into the central basin of the Lake. Model data
suggests the surface front will push into the northern U.P. within
the next 3 hours. This front will be the feature of interest today
as it backdoors down the long axis lakes of Lake Michigan and Lake
Huron with quiet surface ridging preceding its arrival over
southeastern Michigan. Pattern recognition supports and model data
suggests an optimal setup for a pneumonia front surge later today
for both far eastern Wisconsin and southeastern Michigan. In fact,
model data is more bullish for a Pneumonia Front event here in
southeastern Michigan, primarily for the northern and eastern
sections of the cwa.
Sifting through raw surface output suggests a frontal passage that
will have the potential to result in 1 hr temperature drops of 15 to
17 degrees in 1 hour. High temperatures preceding the front are
expected to be in the mid to upper 60s, dropping to approximately 50
degrees rapidly after passage. Timing of the front is expected to be
through Huron County between 19 and 21Z, Bay and Saginaw Counties
between 21 and 23Z, and Port Huron between 22 and 23Z. The coldest
of the marine air is forecasted to surge into the Port Huron area
where it is certainly possible that temperatures could drop at least
20 degrees in a couple of hours, down into the lower 40s before 00Z.
A short duration of gusty winds will be supported directly behind
the frontal passage. At this time, it appears that winds will gust
between 15 and 25 knots, with highest winds probably in Bay and
Saginaw Counties because of a long fetch down Saginaw Bay. The lake
modified air mass is then expected to backdooor across all of the
area this evening. Once nocturnal cooling begins to take off this
will dampen the effects of the frontal passage for the most of
The main baroclinic zone will remain well north of the state
overnight which will allow temperatures to warm again with daytime
heating on Monday. Very little advection will occur with the mean
lower tropospheric air mass which suggests daytime highs Monday very
similar to Sunday, middle to upper 60s most areas.
Geopotential height rebound as well as, a shortwave ridge will push
through the region Monday night and Tuesday. This will set the
stages for an amplifying ridge over much of far eastern North America
for the middle to end of the week. Expecting temperatures pushing 70
degrees Tuesday with temperatures climbing into the middle 70s for
Wednesday. All signs suggest a sharp edge will be set for the
western periphery of the ridge. Alot of uncertainly remains as to
when precipitation chances will increase. At this time, it appears
the best potential for showers and thunderstorms could be anywhere
from Wednesday afternoon to Thursday morning.
High pressure remains in place across but will slowly get pushed
southward by a weakening cold front dropping through the region
today and tonight. The front will do little more than shift winds to
the north and produce some clouds as it passes. Winds will turn to
the east Sunday night into Monday behind this front. Gusts will once
again increase and range between 20 and 25 knots on Monday, mainly
over far northern Lake Huron.
MI...Frost Advisory until 8 AM EDT this morning for MIZ060>063-068>070-
Lake Huron...Small Craft Advisory from 2 PM this afternoon to 10 PM EDT this
evening for LHZ421-422.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
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