Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 231132
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
732 AM EDT Sat Mar 23 2019


.AVIATION...

Differential 1000-500mb height rises will force the surface high
pressure ridge to build across Southeast Michigan today. An
extremely dry air mass coupled with strong static stability between
4.0 and 12.0 kft agl will ensure clear skies.

.DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 417 AM EDT Sat Mar 23 2019

DISCUSSION...

MSAS analyses this morning depict the center of a 1025mb surface
anticyclone anchored along the western shoreline of Lake Michigan.
The surface high is an artifact of upper level confluent flow and
high midlevel stability. While temporarily blocked, the surface
anticyclone will expand more aggressively into Southeast Michigan
today in response to differential 1000-500mb height rises as the
anomalous midlevel cold pool migrates eastward. The area is all but
assured of cloud free skies given the dewpoint depressions
throughout the entire column in the forecast soundings. With full
insolation, light westerly wind trajectory, and mixing heights that
are forecasted to reach approximately 3300 ft agl, wanted to go a
degree or two higher than MOS for max temperatures today. Forecasted
highs are expected to reach the upper 40s during the late afternoon.

Quiescent weather conditions tonight with surface ridging in place.
Virtually no gradient will result in a surface based inversion.
Given no tangible near surface moisture not expecting much of
an impact.

Vertically stacked low pressure disturbance will be in the process
of pushing eastward as a southern jet max develops a linkage to the
southern periphery of the cyclonic circulation. Current model data
suggests less organization and slower timing to the development of a
weak baroclinic zone immediately south of Lower Michigan on Sunday.
This results in a slight slowing of the impact to the passing wave
for Sunday evening. Differences exist with the system, primarily
with the likelihood and potential duration of low-midlevel
deformation. Meanwhile, models have been absolutely steadfast in
showing an inertially unstable setup that will result in a rapid
transition to anticyclonic flow trajectories over the Great Lakes
and a hyper aggressive backdoor cold front right out of Canada.
Precipitation type will be dependent upon the timing of this
backdoor cold front. Earlier timing of the front will likely
suppress the frontal wave to the south and east, while optimal
timing of the low level cold air advection may result in a
changeover to snow and a minor accumulation before precipitation
ends. The ECMWF is the most bearish of solutions, and generally used
the output to direct timing of precipitation type. Otherwise, the
main edit to the forecast was to increase PoPs Sunday afternoon and
evening.

Aggressive surface high pressure will build into the Great Lakes
region for the beginning to middle of next week. Below normal
temperatures are anticipated both Monday and Tuesday.

MARINE...

There will be a steady decrease in the winds and waves across the
lakes this morning into the afternoon as the gradient weakens with
high pressure expanding across the Ohio Valley. Winds will back
toward the southwest during the afternoon and there will be a modest
uptick in the speeds as a cold front advances into the northern
Great Lakes from the north Saturday night. This front will push
south across Lake Huron on Sunday and will be marked by a rapid wind
shift to the north-northeast. Strong high pressure forecast to
expand across northern Ontario and low pressure traversing the Ohio
Valley will result in an increasing northeasterly gradient across
the area Sunday night and into Monday, with wind gusts possibly
reaching 30 knots on southern Lake Huron. This will likely result in
small craft advisory conditions on Lake Huron. Winds and waves will
then decrease Monday night into Tuesday as high pressure becomes
centered over the region.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory until 11 AM EDT this morning for LHZ421-
     441>443.

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

$$

AVIATION.....CB
DISCUSSION...CB
MARINE.......CB


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