FXUS63 KDTX 171850
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
250 PM EDT Tue Jul 17 2018
Dry weather will continue over the next couple of days with
temperatures just slightly below normal (mainly mins).
Upper level trough axis sliding through the Central Great Lakes this
afternoon/evening, with large anticyclone building in behind for
Wednesday. Decent CU development today, especially over northern
Lower Michigan, and NAM/Regional Gem CU rules paint equal or even
slightly better coverage over southeast Michigan tomorrow, as winds
come off Lake Huron tonight. Marine influence/inland heat low
developing should favor clouds mainly along and west of U.S. 23 by
late afternoon hours.
Afternoon dew pts have fallen into the 50s, with even a few upper
40s popping up, which looks good for mins tonight and supported by
latest MAV guidance.
Similar to slightly cooler high temperatures expected tomorrow
(upper 70s to lower 80s) with the cooler start and surface high
Return flow around the high begins to kick in on Thursday with
increasing low level southeast winds, favoring warmest locations
across Tri-Cities and Flint Vicinity. 850 MB temps progged to reach
16 C (per 12z Euro), supportive of highs reaching into the low to
mid 80s, even with some additional cu development.
Upper level energy currently over the Pacific Northwest is still on
track to move into the Great Lakes by Friday as a closed upper low,
bringing an end to the streak of dry and quiet weather. Ample
moisture (PWAT values in excess of 1.5 inches) will move into the
area ahead of this and will result in numerous rounds of scattered
showers and thunderstorms for Friday through Monday as the upper low
stalls over the region. Temperatures during this period will be the
warmest on Friday in the lower to mid 80s, cooling to the upper 70s
to lower 80s for the remainder of the weekend and into early next
week. Weak ridging returning to the area looks to keep next Tuesday
quiet as the upper low disperses and moves east.
NNW flow gusting up to 20 knots throughout the daylight hours will
help produce max wave heights ranging between 3 - 5 feet late
tonight into the early morning hours of Wednesday, resulting in a
small craft advisory during this time frame along the tip of the
thumb. Winds and thus wave heights will start to relax overnight as
a high pressure system settles in across the Great Lakes. This high
will result in tranquil marine conditions through Thursday.
Issued at 1244 PM EDT Tue Jul 17 2018
Diurnal heating has helped produce a scattered deck of cumulus
between 4-5 kft across most terminals during the late morning and
early afternoon. Mixing and entrainment of drier air aloft should
minimize expansion of cumulus deck throughout the afternoon and
evening. Otherwise, anticyclonic flow around an approaching high
pressure system in conjunction with a weak lake breeze will help veer
winds from the northwest to northeast between 00-02Z. The brief
switch in wind direction will help advect some moisture off of Lake
Huron which will act to hold a SCT deck of cu across the terminals
overnight. Went with optimistic TAFs, holding onto this SCT deck as
high pressure should help suppress expansive cloud cover, however,
latest hi-res models hint at the possibility of seeing a BKN deck
between 4 - 5 kft, mainly over MBS, FNT, PTK. Wind direction is then
expected to shift back to the northwest late tonight as lake breeze
dynamics weaken, which will then again bring dry air into the region
as high pressure settles across SE MI.
DTW THRESHOLD PROBABILITIES...
* Low for ceilings at or below 5kft overnight.
Lake Huron...Small Craft Advisory from 8 PM this evening to 4 AM EDT Wednesday
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
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