106 FXUS63 KDTX 161945 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 345 PM EDT Sun Oct 16 2022 .DISCUSSION... Robust pv anomaly cascading down the backside of the pervasive mean longwave trough on pace to expand across the great lakes over the next 24 hours. Substantial consolidation of the inbound height falls will establish a 531 dm closed low atop the region on Monday, ensuring an intermittently active pattern lasting throughout the early week period as temperatures spiral downward accordingly. Lead edge of these height falls infiltrate beginning this evening, offering an initial window for possible shower production along the attendant cold frontal passage. Conditions then likely to remain unsettled overnight and Monday morning, as ongoing strong dcva and cold air advection tap into an increasing supply of both synoptic and lake moisture within west-northwest flow. A steepening lapse rate environment will contribute to some heavier convective showers (and maybe a rumble of thunder) within a scattered to numerous coverage. Much colder conditions firmly entrenched Monday with 850 mb temperatures already at -3 to -4c by mid morning. Advent of daytime heating combined with the resident cold pool aloft establishes tremendous convective depth throughout the day. This will continue to offer a favorable environment for at least a chaotic coverage of showers at times. Potential for a more organized response during the afternoon and evening to anchor along a southward propagating mid level trough axis and low level frontal zone trailing the exiting upper low. A weakly unstable profile would support pockets of heavier showers with the possibility of embedded thunder, with the lower freezing levels perhaps affording some occurrences of graupel or snow showers within the heaviest cores. Very limited diurnal temp recovery as low level thermal troughing takes root during the day. Highs low to mid 40s, with a firm westerly gradient gusting 25 to 30 mph at times contributing to this downgrade in overall conditions. Conditions remain marked by deep layer cold northwest flow under high amplitude troughing Tuesday and Wednesday, as the closed mid level circulation lingers over southern Ontario and western Quebec during this time. A steady stream of vorticity working through the cold cyclonic flow will maintain potential for shower production through at least Tuesday evening, as organized ascent capitalizes on a moist, lake augmented profile and noted uptick in lapse rates during the daylight period. Thermal profile again supportive of a few snow showers or mix, particularly within any higher intensity rates. Blustery conditions with temperatures again parked in the 40s Tuesday. Low level thermal troughing holds tight through Wednesday, with the lack of meaningful advection effectively ensuring both minimal airmass recovery and maintenance of existing lake moisture cloud. Shower potential less definitive this period, but the underlying pattern would suggest at least a low end, diurnally driven opportunity given lingering vulnerability for additional shortwave energy to slide through. This may eventually necessitate an upward adjustment in precip chances should a greater signal emerge. Stubborn closed low now parked near Hudson Bay will maintain influence through Thursday. Coldest air within this pattern actually fixated locally at 12z Thursday, featuring 850 mb temperatures invof -7c. Some modest recovery possible as large scale heights build gradually, but still looking at temperatures solidly 10+ degrees below normal. Long range guidance even hints at yet another shortwave perhaps presenting one lingering shot of rain in this dismal fall pattern. Warming trend and increasingly insolation potential Friday into next weekend. && .MARINE... An upper-level low will continue to linger over the central Great Lakes into the midweek period before finally lifting northeastward towards Quebec towards the latter half of the week. Surface low pressure will develop and deepen across the Lake Huron basin tonight and through Tuesday allowing for another surge of colder air and strengthening winds across the local waters. The tightened pressure gradient and increase in over-water instability will result in an increasing potential for north/northwest gales across all of the Lake Huron basin, including nearshore waters and Saginaw Bay, and a Gale Watch is in effect late Monday afternoon through Tuesday evening. Strongest gusts are expected across northern and central portions of the open Lake Huron waters where gusts to 40 knots at times will be possible Monday night into Tuesday morning. Hazardous small craft conditions will also be likely across Lake St. Clair and western Lake Erie during this time. In addition to numerous to widespread showers at times during this period as well, waterspouts will also be possible mainly across the Lake Huron basin. As the upper-level low lifts towards Quebec into the latter half of the week, northwest flow will back more westerly and gradually wane with time as higher pressure builds in from the Midwest. Drier conditions will prevail during this time as well. && .PREV DISCUSSION... Issued at 159 PM EDT Sun Oct 16 2022 AVIATION... VFR conditions to start the period, and may well continue through the day into tonight. A cold front will finish passing east through the area in the next hour or so, which is bringing westerly flow and colder air into the region. This will initiate lake effect clouds and showers this afternoon. Dry air locally will make it tough for precipitation to reach southeast MI this afternoon, but chances increase around 00Z as low pressure sets up over the state and brings additional support for showers. Tough call on timing precip in the tafs as showers will be very scattered. Put a tempo in this evening for a better push of moisture, but widely scattered showers could go on throughout the night. MVFR cigs look to arrive later tonight with the secondary push of moisture. Another front pivoting around the low will bring additional shower chances on Monday. DTW THRESHOLD PROBABILITIES... * Moderate for ceiling 5000 feet tonight through Monday. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...Gale Watch from Monday afternoon through Tuesday evening for LHZ361>363-421-422-441>443-462>464. Lake St Clair...Small Craft Advisory from 4 PM Monday to 8 AM EDT Wednesday for LCZ460. Michigan waters of Lake Erie...Small Craft Advisory from 2 AM Monday to 8 AM EDT Wednesday for LEZ444. && $$ DISCUSSION...MR MARINE.......IRL AVIATION.....DRK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.