Sunrise 6:35 AM   Sunset 8:24 PM Moonrise 7:24 PM   Moonset 5:19 AM

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LCZ422 /o.exp.kdtx.ma.w.0003.000000t0000z-240417t2115z/ 505 Pm Edt Wed Apr 17 2024
.the special marine warning will expire at 515 pm edt - .
the affected areas were - . Lake st. Clair open lake (u.s. Portion) - . St. Clair river - .
the Thunderstorms have moved out of the area and no longer pose a significant threat to boaters.
a severe Thunderstorm watch remains in effect until 700 pm edt for southeastern michigan - .the adjacent waters of lake huron - .and the adjacent waters of lake st. Clair.
&&
lat - .lon 4289 8247 4280 8248 4276 8247 4261 8252 4255 8259 4256 8264 4246 8274 4259 8285 4266 8285 4272 8269 4270 8261 4265 8259 4264 8256 4276 8251 4289 8252 4301 8247 4302 8243 4298 8241 time - .mot - .loc 2105z 242deg 52kt 4323 8228 4292 8200 4269 8178

LCZ400
No data

FXUS63 KDTX 231949 AFDDTX

Area Forecast Discussion National Weather Service Detroit/Pontiac MI 349 PM EDT Tue Apr 23 2024

KEY MESSAGES

- Shower and thunderstorm chances increase this evening ahead of a cold front. There is potential for hail with any thunderstorm activity.

- Breezy late tonight with gusts up to 30 mph in the Thumb.

- A Freeze Watch is in effect for all of southeast MI late Wednesday night through early Thursday morning as overnight lows dip into the upper 20s.

- Rain chances increase Friday night as a series of lows lift into the upper Midwest. There is low confidence in shower and thunderstorm potential Saturday and Sunday.

DISCUSSION

Frontal forcing has lifted into southern lower Michigan, with a band of steady rain filling into Lenawee and Monroe Counties as of issuance. This band is expected to hold along/south of I-94 before shearing southeast late this evening. Attention then turns to the cumulus field upstream across northern lower MI-WI-MN where convective cells have been developing over the past couple hours invof the mid-level wave and trailing cold front. Expectation is for these showers and thunderstorms to move into the Tri Cities and Thumb region between 22-00z (6-8pm local) and track southeast across the rest of the cwa tonight. Steep mid level lapse rates approach 8 C/km upstream, which will advect into northern portions of the cwa and be the main catalyst for a stronger updraft or two this evening.
Widespread strong storms are not expected, however, as low instability will struggle to maintain updrafts in such high shear.

The upper level trough and surface front will slide southeast into Lake Erie by daybreak Wednesday, ushering out any lingering showers.
Breezy conditions linger through the morning, especially around the Thumb region where gusts may approach 30 mph. Morning lows will reflect post-frontal cold advection, as some spots around the Tri Cities and Thumb will see temperatures near freezing and wind chills in the teens. Standard subsidence inversion settles between 3.0-5.0 kft agl, initially trapping leftover moisture and maintaining a thick stratus deck for the morning. A much drier low level airmass then advects south Wednesday afternoon, dropping PWAT values below 0.25" (below the 10th percentile per SPC climo) and quickly mixing out clouds by afternoon. H8 temperatures dropping into the single digits during the day leads to a range of temperatures from near 40 degrees in the Thumb to low 50s for inland and urban locations.

Dry weather persists through mid-day Friday as heights build and a roughly 1030 mb surface high stalls overhead. Opportunities for cloud cover remain limited, with just a glancing stream of high cloud moving in Thursday invof a low amplitude wave. Main concern during this time window is sub-freezing temperatures (upper 20s)
Thursday morning, in which a Freeze Watch has been issued overnight Wednesday through Thursday morning.

Benign conditions come to an end Friday afternoon as the next storm system ejects out of the Plains and into the Upper Midwest. The primary circulation will stay well to our west, but will push the warm conveyor and associated moist isentropic upglide right overhead by Friday evening. A strong low level jet, 40-45 knots at 850 mb, contributes to substantial warm advection and moisture transport into the area at this point, increasing confidence in a period of widespread rain Friday night and a gradual warm up through the weekend. Temperatures Saturday and Sunday look to climb comfortably into the 70s.

Precipitation prospects for the weekend offer much less certainty, beginning with a mid-level dry slot that arrives Saturday morning.
This creates a highly conditional convective setup in which available long-range guidance struggles with depth and magnitude of static stability within the dry slot. If the atmosphere is dry and capped (e.g. 00z Euro), convection would struggle to initiate and be reliant on a warm/moist boundary layer that may not come to fruition. On the other hand, favorable return flow and opportunity for the SE CONUS ridge to direct embedded shortwaves toward lower MI (e.g. 12z GFS) Saturday and Sunday will warrant monitoring for thunderstorm potential.

MARINE

A Small Craft Advisory will expire at 4 PM today as gusty winds and heightened waves diminish into the evening hours. Surface low pressure associated with an upper level disturbance crossing the Midwest has shifted south, becoming more diffuse over The Straits as a secondary surface low emerges further west. Expect some additional rounds of showers this evening, including the potential for a few thunderstorms that could result in locally higher winds/waves. Most of the convective activity should develop ahead of the system's cold front through before colder post-frontal air filters overnight. This leads to brisk northerly flow and low-end potential for gusts to gales while lapse rates steepen and forecast soundings are well- mixed once stronger LLJ winds clip central Lake Huron. Will likely issue another Small Craft Advisory for Saginaw Bay and The Thumb with the evening marine update. Gradient winds trend lower midday Wednesday before high pressure starts building into the Great Lakes.
More favorable marine conditions are expected Thursday with sustained ridging until Friday. Unsettled weather returns Saturday, dependent on trajectory of a large low pressure system ejecting from The Plains.

PREV DISCUSSION
Issued at 115 PM EDT Tue Apr 23 2024

AVIATION...

Light rain my work back into the I-94 corridor this afternoon, but trends suggest most of this will be a bit further south. Will adjust forecast to limit duration and increase cig/vsby restrictions. To the north of this, scattered showers will develop by early evening within pocket of marginal instability between light rain to the south and cold front to the north. A few thunderstorms will even be possible along front as it drops south through the area later in the evening. MVFR cigs should occur in the wake of the front. Southwest winds will gust to 25-30 kts this afternoon and then veer to north 06z-10z from north to south.

For DTW/D21 Convection...Confidence is low on occurrence of thunder this evening as a cold front encroaches on the region. Any activity would be isolated and likely weakening as it tracks into the more stable sector KPTK south after initially developing within an area of marginal instability from KFNT north.

DTW THRESHOLD PROBABILITIES...

* Medium confidence in ceilings aob 5 kft after 21z today, high late tonight into Wednesday morning.

* Low in thunderstorms impacting the terminal late this evening.



DTX WATCHES/WARNINGS/ADVISORIES
MI...Freeze Watch from late Wednesday night through Thursday morning for MIZ047>049-053>055-060>063-068>070-075-076-082-083.

Lake Huron...Small Craft Advisory until 4 PM EDT this afternoon for LHZ421-422- 441>443.

Lake St Clair...Small Craft Advisory until 4 PM EDT this afternoon for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 4 PM EDT this afternoon for LEZ444.

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