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Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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069 FXUS63 KDTX 191650 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 1250 PM EDT Fri Jul 19 2024 .KEY MESSAGES... * Seasonably cool and dry conditions today and most of the weekend. High temperatures warm gradually into the mid 80s by Sunday. * Low chance for showers Sunday and Monday afternoon north of I-69, with more widespread precipitation possible middle of next week. && .AVIATION... High pressure drifts overhead through the period maintaining light winds and VFR cloud. SCT-BKN cumulus that developed late morning dissipates with the loss of diurnal heating this evening setting up another clear night. For DTW/D21 Convection...No convection is expected through the TAF period. DTW THRESHOLD PROBABILITIES... * Medium for ceilings aob 5000ft early this afternoon. Low by late afternoon. && .PREV DISCUSSION... Issued at 326 AM EDT Fri Jul 19 2024 DISCUSSION... Surface high pressure slowly inches eastward into the Great Lakes today, affording another day of deep static stability and corresponding dry weather. Observed 850mb temperature of 9 C, per the 00z KDTX sounding, is in the 10th percentile for this time of year (NAEFS/SPC climo) as daytime highs fall a few degrees short of normal around 80 degrees. Forecast soundings are notably drier in the boundary layer than yesterday, so expecting a muted diurnal cumulus response in comparison, yielding mostly sunny skies. The semi-permanent high over the Four Corners region and column winds under 15 knots in the lowest 20.0 kft agl create little opportunity for thermal advection. This equates to a gradual warmup through the weekend as temperatures climb a couple degrees each day due to airmass modification. Daytime highs by this weekend settle in the low to mid 80s, which hold through middle of next week. The weak flow pattern aloft allows a cutoff low to develop and stall over the upper Mississippi Valley by Saturday morning. Precipitation from this system will stay to our southwest, but its presence will halt southward advancement of a Canadian cold front this weekend. The stalled front acts as a deformation axis, most notable in the 850-700mb layer, which will engage existing frontal moisture and weak instability (~500 J/kg MLCAPE) to create isolated showers and perhaps a thunderstorm for the Tri Cities/Thumb both Sunday and Monday afternoon. The low dislodges by mid-week in response to an inbound northern stream shortwave, increasing chances for widespread precipitation toward the end of the forecast period. MARINE... Expansive high pressure over the Midwest into the Great Lakes region will lead to light winds (under 20 knots) right into early next week. The next chance of showers and thunderstorms does not look to arrive until Tuesday, with a low chance continuing through Thursday. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....KDK DISCUSSION...MV MARINE.......sf You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.