Sunrise 6:41 AM   Sunset 8:19 PM Moonrise 3:15 PM   Moonset 4:07 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 191906 AFDDTX

Area Forecast Discussion National Weather Service Detroit/Pontiac MI 306 PM EDT Fri Apr 19 2024

KEY MESSAGES

- Cool and quiet weather this weekend. Frost is possible Saturday night and Sunday night.

- Next chance of showers and thunderstorms arrives Tuesday.

DISCUSSION

Mid level subsidence has fostered a period of respectable post frontal drying which has led to a sunny albeit cool afternoon across Se Mi. A region of high based clouds now over IL/IN will lift northeast across potions of Se Mi this evening. These are the result of some weak mid level isentropic ascent within the entrance region of a mid level jet streak. A decrease in the clouds overnight and a very dry boundary layer will support enough radiational cooling to drop overnight temps into the 30s. A mid level short wave trough axis now over the Dakotas and Minnesota will rotate across Se Mi during the morning on Saturday. Despite the mid level height falls and differential vorticity advection, the column will remain very dry and not supportive of precip. The passage of this wave will drive colder air into Se Mi (850mb temps of -6 to -8c) by afternoon.
Model soundings also indicate steep low level lapse rates with enough moisture to support a healthy cu field during the afternoon.
This will keep afternoon temps in the mid 40s to near 50. With 20 to 25 knot westerly winds in the mixed layer, it will be a rather brisk spring day. The gradient flow will persist through Sat night. Given the degree of cold air, Sat night mins still are forecast to drop into the low to mid 30s.

A polar low is forecast to slide across James Bay into northern Quebec Sunday into Monday. Lower Mi will be within the mid level confluence between this feature and an upstream ridge. This will sustain broad large scale subsidence and dry conditions across the region. The upper low is forecast to a drive a shallow cold front across Lake Huron Sunday afternoon/evening. This front will likely weaken Sun night before lifting north as a warm front on Monday as developing southwest flow begins to drive slightly warmer air across Lower Mi.

Forecast amplification of a mid level wave emerging from the northern Rockies and traversing the Great Lakes Tues/Tues night will support the next chance for rain. Moisture transport into this system along with good large scale ascent will support a 60-70 percent of showers. Weak elevated instability will also warrant a chance for a thunderstorm. Model solutions diverge in their handling of a secondary upper wave forecast to advance across southern Hudson Bay Tues night/Wed. The GFS camp drives this wave south into the Great Lakes region on Wednesday, while the ECMWF/UKMEt/Canadian all shear this wave eastward into northern Quebec. These differences will impact the degree of cold air advection (if any) Wed into Thursday with the GFS being quite a bit colder. The current ensemble blend forecast will feature late week temps just slightly below seasonal averages attm.

MARINE

Cooler post-frontal westerly flow continues through the evening as gusts generally top out in the 20-25kt range, though near 30kts possible over the Saginaw Bay. An upper level trough currently settling over the Great Lakes holds overhead through the weekend leading to fairly consistent day-to-day conditions for the central Great Lakes. Some variability in wind direction (between west and northwest) is likely as disturbances embedded within the trough swing across northern Ontario. The cooler airmass maintains unstable overlake thermal profiles to support efficient mixing of winds down to the surface resulting in moderate winds through this timeframe with peak gusts for the majority of the region between 20-25kts. The exception will be northern Lake Huron where winds have the best potential to reach 30kts. Small craft advisories remain in effect for the Saginaw Bay and tip of the Thumb nearshore waters through Saturday afternoon due to a combination of winds and waves. These waters likely will require another advisory daytime Sunday as rougher conditions look to redevelop.

PREV DISCUSSION
Issued at 151 PM EDT Fri Apr 19 2024

AVIATION...

Ridge of high pressure and ongoing deep layer subsidence will promote clear skies through the remainder of the afternoon and evening. Sustained winds of 10 to 15 knots with gusts around 25 knots remain probable with the continued daytime mixing. Some development of clouds around 6kft will be possible late tonight and overnight as low-level moisture filters in along a frontal boundary, but confidence regarding the materialization and coverage of this potential cloud coverage is low for the overnight period. By late tomorrow morning and into the afternoon, cold air advection will induce steep low level lapse rates, promoting robust strato-cu development around 6kft.

DTW THRESHOLD PROBABILITIES...

* None



DTX WATCHES/WARNINGS/ADVISORIES
MI...None.
Lake Huron...Small Craft Advisory until 4 PM EDT Saturday for LHZ421-422-441.

Lake St Clair...None.
Michigan waters of Lake Erie...None.

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