NWS Forecast Discussion

571
FXUS63 KDTX 240657
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
257 AM EDT Mon Jul 24 2017

.DISCUSSION...

Upper low spinning near Georgian Bay will open as it drops southeast
through Ontario today. Surface low pressure out ahead of it will
track away from the area, leaving cool northwest flow in its wake as
high pressure builds into the Upper Mississippi River Valley and
western Great Lakes. Cool flow off Lake Huron will supplement low-
level moisture lingering behind a cold front, while dry air remains
in place in the mid-levels. This will promote some low-topped
showers or drizzle early this morning and today, mainly over the
thumb. Otherwise, it will feel and look a little fall-like today
with low stratus lingering, locked under an inversion, and north
winds around 10-15 mph. Temperatures will run cool for late July
with max temps only in the mid/upper 60s over the thumb and low/mid
70s elsewhere. High pressure will expand into the area tonight and
last through late Tuesday, bringing dry and quiet weather. Tuesday`s
max temps will bounce back into the mid 70s to near 80 under
plentiful sunshine.

Upper low now over Alberta and shortwave energy diving down off the
west coast of Canada will move east through mid-week, breaking down
an upper ridge that will be positioned over the Great Lakes. This
will ultimately drive a cold front and an area of low pressure
across the region, with models still struggling to resolve placement
of the low track and timing of the front. Latest trends are for a
slower frontal passage through Lower Michigan, with solutions now
clustered more on Thursday as opposed to Wednesday night, and for a
low track to our south over the Ohio Valley. Showers and
thunderstorms look to develop over the area, but a low track to our
south may limit instability and keep deeper moisture from reaching
up into Michigan. Will hold shower/tstorm coverage only at scattered
and continue to monitor model solutions for changes as the upper
features become better sampled over the next 24 hours.

&&

.MARINE...

Low pressure will deepen over the eastern Great Lakes today with a
surface trough pivoting southeast from southern Lake Huron during
the morning around this low. A period of enhanced north-northeast
gradient flow will occur on the back side of this trough across Lake
Huron. Cooler air overspreading the relatively warm lake will also
boost mixing depths.

The result will be a push of stronger winds, 20 to 30 knot gusts,
across Lake Huron from early this morning into this afternoon. This
will bring a period of rather high wave action for July. In fact,
wave heights in excess of 6 feet have already been noted over the
northern portion of the lake where northeast wind gusts have already
approached 30 knots. These conditions will spread south and bring
rough conditions for small crafts. Hence, advisories are in effect
for the nearshore waters. Winds and waves will then decrease tonight
into Tuesday as high pressure builds in from the west.

&&

.PREV DISCUSSION...
Issued at 1152 PM EDT Sun Jul 23 2017

AVIATION...

Steady southward expansion of low stratus expected overnight as a
cold front effectively shifts the deep moisture plume out of the
state.  Upstream satellite and observational trends suggest ceiling
bases will arrive at IFR or lower MVFR during the early and mid
morning period.  A drying environment along with daytime mixing
will lift ceilings through the afternoon.  Modest northwest wind
becoming northerly on Monday.

For DTW...Timing on the cold front and arrival of MVFR ceiling
remains centered during the mid morning hours /10-11z/.  Cigs below
5000 ft likely thru early tomorrow afternoon.

//DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5000 feet late tonight through Monday
  afternoon


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement from 8 AM EDT this morning through this
     evening for MIZ048-049-055-063.

Lake Huron...Small Craft Advisory from 6 AM this morning to 4 AM EDT Tuesday for
     LHZ441.

     Small Craft Advisory from 8 AM this morning to 4 AM EDT Tuesday for
     LHZ442-443.

     Small Craft Advisory from 6 AM this morning to 8 PM EDT this
     evening for LHZ421-422.

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

$$

DISCUSSION...HLO
MARINE.......DG
AVIATION.....MR


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NWS DTX Office Area Forecast Discussion