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000
FXUS63 KDTX 181956
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
356 PM EDT Thu Apr 18 2024

.KEY MESSAGES...

- Rain tonight as a cold front tracks through the region.  A few
  rumbles of thunder cannot be ruled out.

- Showers exit Friday morning with drier and cooler weather heading
  into the weekend.

&&

.DISCUSSION...

Low and mid level ridging entrenched locally late this afternoon,
immediately downstream of a broadening corridor of height falls
emanating off a closed mid level circulation pivoting into western
Ontario. Active southern stream pv and upper jet energy undercutting
this height fall gradient will prompt a respectable low and mid
level response offering an axis of meaningful northward moisture
transport within the background ongoing warm air advection. This
process occurs as the associated surface reflection and attendant
frontal boundary migrate across lower Michigan tonight. Ongoing
higher based isentropic ascent currently offering some thicker
cirrus with a representative signal of virga/sprinkles across the
Saginaw valley, but limited moisture quality or supportive ascent
lends to otherwise dry conditions holding this evening. Peak in both
upward vertical motion and theta-e quality occurs over roughly a 6
hour window from 04z to 10z as fgen strengthens along the northwest
flank of the passing surface low. This will support a high coverage
of rain within this window, with some elevated thunder potential
given the magnitude of theta-e advection. Rainfall totals from one
quarter to one half inch remain on track.

Aforementioned closed low remains a fixture Friday and Saturday as
it slowly migrates across central Ontario. Modest height falls
within the post-frontal environment nets an associated cooling trend
this period. Weak advective process initially leaves highs solidly
in the 50s Friday. A secondary frontal passage Friday night offers a
reinforcing shot of colder air with a more noteworthy downward
adjustment for Saturday with highs upper 40s/lower 50s. Firm
pressure gradient with sufficient wind magnitude affords a standard
increase in gustiness of west winds with daytime heating both days.
Dry conditions hold this period as moisture depth remains too
limited to generate anything outside of a broader stratocu field
within weakly cyclonic mid level flow. Dry and seasonable conditions
remain through the end of the weekend. Brief recovery of mid level
heights then brings a modest warming trend heading into early next
week.

&&

.MARINE...

A cold front sags south through the central Great Lakes tonight into
Friday morning bringing widespread showers as well as a slight
chance for a couple nonsevere thunderstorms over the southern lakes.
Upper level troughing expands over the Great Lakes following the
frontal passage allowing a cooler airmass to settle over the region
through this weekend. A destabilizing overlake thermal profile
supports moderate west to northwest flow for this timeframe as peak
gusts over northern Lake Huron top out in the 25-30kt range, with 20-
25kts generally favored over the remainder of the area.

&&

.PREV DISCUSSION...
Issued at Issued by National Weather Service Grand Rapids MI

AVIATION...

Increasing cirrus this afternoon will become obscured by a return to MVFR
cigs overnight tonight as an area of showers accompany a cold front.
IFR ceiling restrictions after 06Z are not high probability but certainly
possible. As noted before, wind direction will fluctuate substantially
between now and 12Z Friday as the cold front traverses the area.
There is a couple hour window centered around 06Z tonight where
there will be a low probability for thunder across extreme southeast
Lower Michigan and this could brush KYIP. However, this remains too
improbable at this time to warrant mentioning in the terminals.

DTW THRESHOLD PROBABILITIES...

* High for ceiling aob 5000 ft after 04z-06z tonight.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

DISCUSSION...MR
MARINE.......KDK
AVIATION.....TJT


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