Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS63 KDTX 221739 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 139 PM EDT Fri Mar 22 2024 .KEY MESSAGES...
-- Changed Discussion --
- A Winter Weather Advisory remains in effect Friday for a greater portion of SE MI. New accumulation totals of 1-4 inches will be possible for counties that remain within the Winter Weather Advisory, with higher end totals favored along or north of M-59. Highly localized snowfall totals will be possible with any snow banding. - Dry weather but below average temperatures return this weekend. - Warmer temperatures and rain showers return for early next week.
-- End Changed Discussion --
&& .AVIATION...
-- Changed Discussion --
A shallow dry slot has temporarily ceased snowfall production across the Metro terminals while multiple elevated frontal boundaries continue to produce widely varying snow intensity across the remaining terminals. The forcing from the elevated boundary across the Tri-Cities will initially intensify through this afternoon which will result in periodic heavy snowfall rates which will likely reduce visibilities down to LIFR at times. This frontal boundary will then sweep southeast through the evening hours, sustaining snow across KFNT and KPTK, and bringing the return of snow to the Metro terminals. Cigs are expected to periodically range between MVFR-IFR along the front, where visibilities to or below 1SM will be possible. Snow will abruptly come to an end after the passage of the front, where MVFR/IFR cigs will likely sustain in the wake of the front. For DTW... A lull in snowfall is expected to last through the early evening hours. A cold front will bring a window of snow tonight, roughly between 01Z to 05Z. There may be a brief hour window within this time frame with moderate to heavy snowfall that can quickly produce an inch of snow accumulation. .DTW THRESHOLD PROBABILITIES... * High for snow as precipitation type. * Low in ceilings aob 5000 feet this afternoon, high late tonight with snowfall.
-- End Changed Discussion --
&& .PREV DISCUSSION... Issued at 319 AM EDT Fri Mar 22 2024 DISCUSSION... Lead arm of elevated warm advection tied to a partially sheared Plains shortwave is on the doorstep of SE MI at time of discussion. Upstream observations have shown a cellular/convective component to associated snow showers with this expected to continue as it works into our area as elevated instability (between 500-700mb) creeps in from the south. Forecast soundings nearly all advertise impressive strengthening frontogenetic forcing/ascent along the ~700-550mb frontal slope as snow expands between the I-69 to I-94 corridors this morning, which also coincides with the region of the column where the DGZ is residing. Combination of these factors is increasing concern for an area of overachievement in snow rates exceeding 1 inch per hour somewhere across the southern advisory counties (Livingston, Oakland, Macomb) as well as the northernmost portions of Washtenaw/Wayne counties. While the more mesoscale nature of this potential band carries low spatial predictability, there is enough confidence/concern that we have added the I-94 corridor counties into the advisory given the window for enhanced rates occurs at least partially within the morning rush hour period. Overall, areas south of I-69 have the potential to pick up a quick 2- 4" this morning, though if higher rates are realized, can`t completely rule out a localized area approaching 5". For areas north of I-69, the higher active frontal slope, aoa 500mb, both prevents a convective component like areas to the south as well as places best saturation/ascent above the DGZ limiting potential accumulations to the 1-3" range through the morning. Warm frontal slope slides further north by midday as the arrival of the main mid-level shortwave over the western Great Lakes results in its reorientation towards SW-NE over the Thumb/Saginaw Valley. Shift allows a modest 800-900mb dry slot to expand over areas south of I- 96/696 (and potentially as far north as M-59) during the afternoon leading to a lull in precip. Conversely, the northern CWA not only continues to see persistent snow but likely increasing intensities as a jet streak develops over Lake Huron/Ontario increasing the fgen response as the right entrance region sets up directly overhead. Additionally with the aforementioned northerly trend in the front, the active frontal slope shifts lower towards the 600-700mb layer. Soundings hint at weak elevated instability being available within this region of the column further strengthening the frontogenetic forcing. Similar to the morning activity over the southern CWA, result is that areas along/north of the I-69 could see a quick 2-4" through this afternoon-early evening. Attendant mid-level cold front works across the region this evening into the first half of tonight as the parent shortwave pushes into southern Ontario. This brings snow back into the southern portions of the CWA as the lingering fgen band is pulled southeast. Some weakening of this banding is possible as it works into the Metro area due to the accompanying jet streak looking to likewise shift further southeast toward Ohio, however CAM guidance remains in disagreement wrt the speed this occurs at. Should this trend occur slow enough, there will be a secondary window for areas south of I- 69 to see a brief heavier burst of snow with rates between 0.5-1"/hr late evening-early tonight (~22-04Z). Potential accumulations will be limited by the bands residence time as it rapidly moves east with 0.5-2" currently expected- lowest amounts towards the state line. High pressure dropping out of the Canadian Prairie expands over the central Great Lakes for Saturday ushering in colder but drier air for the weekend. 850mb temps fall to around -10C for both days resulting in another period of highs holding below normal in the 30s. Active weather looks to make its return early next work week as a potent Pacific mid-upper trough ejects out of the Desert Southwest and into the Midwest/Great Lakes. MARINE... Southeast to east wind increases to between 15 and 20 knots today with some gusts to 25 knots as low pressure tracks from the Plains into the Ohio Valley tonight. This low brings widespread snow across the central Great Lakes with some rain and wintry mix possible across western Lake Erie and Lake St. Clair. Small Craft Advisories are in effect along the Lake Huron shoreline from Port Austin to Port Sanilac where wave heights will build to around 4 to 5 feet today. The system departs late tonight with winds shifting to north/northwest by Saturday morning. Colder air works back into the area with winds becoming gusty to around 20 to 25 knots Saturday. A ridge of high pressure then builds in Saturday night into Sunday with weaker winds expected. The next low pressure system lifting out of the Plains will force a warm front across the region Monday into Tuesday with increasing southeast winds during this period. && .DTX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
MI...Winter Weather Advisory until midnight EDT tonight for MIZ047>049- 053>055-060>063-068>070. Winter Weather Advisory until 2 PM EDT this afternoon for MIZ075- 076. Lake Huron...Small Craft Advisory until 7 PM EDT this evening for LHZ441-442. Lake St Clair...None. Michigan waters of Lake Erie...None.
-- End Changed Discussion --
&& $$ AVIATION.....AM DISCUSSION...KDK MARINE.......TF You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.