Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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
46
47
231 FXUS63 KDTX 282240 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 640 PM EDT Sun Apr 28 2024 .KEY MESSAGES... - Another round of showers and scattered thunderstorms tomorrow, some of which could be strong. - Well above normal temperatures expected continue through the week. && .AVIATION... Although the depth of the front is shallow, there is a very tight thermal gradient along a nearly stationary front located between KFNT and KPTK. Therefore ample post frontal low level moisture capped by a deep low level frontal inversion is supporting IFR clouds along the cool side of this front. Some slight southward movement of this front is expected this evening, likely driving it across KPTK and possibly KDET. Strengthening south flow in the warm sector overnight will then gradually lift the front back north as a warm front. There is likely to be some LIFR and VLIFR conditions on the cool side of the front overnight under additional boundary layer cooling. The best chance for convective development looks to be Monday afternoon, driven by forced ascent along a pre cold frontal trough axis within an unstable environment. For DTW/D21 Convection...Any nighttime convection is expected to remain well west of D21 airspace tonight. A scattered to broken line of thunderstorms is then expected to traverse the airspace from west to east late in the day Monday, 19Z to 01Z. DTW THRESHOLD PROBABILITIES... * Moderate in thunderstorms late Monday. * Low in ceilings at or below 5000 feet tonight. Moderate on Monday. && .PREV DISCUSSION... Issued at 322 PM EDT Sun Apr 28 2024 DISCUSSION... Moist airmass in place over southeast Michigan, as the 12z DTX raob came in with a near record high PW value of 1.35 inches or 221 percent of normal. Short lived, modest mid level dry slot, is moving in for the rest of the afternoon over the Central Great Lakes, which has allowed the widespread showers this morning to taper off. Still have warm frontal boundary hanging around, with enough instability (MLcapes 400-800 J/kg) to potentially trigger convection through the evening hours, mainly north of the boundary (north of M-59). 0-1 KM bulk shear values 30+ knots along/near the front draws concern for cells to rotate, but limited cape and modest mid level lapse rates expected to keep storms non-severe, with 700-500 MB upper level ridging also tending to suppress activity. Large, well developed, mid-upper level low/circulation over the Plains will be slowly lifting northeast into Ontario Tuesday morning. Better large scale support arrives Monday with height falls and surface cold front tracking through during the day. Favorable timing of the front during/near peak heating draws concerns for severe storms, but once again, instability is expected to be limited with MLcapes mainly under 1000 j/kg. Wind fields are elevated, with 850 MB winds (30-40 knots) and favorable 0-6 KM bulk shear around 40 knots. Would not rule out storms approaching severe limits with more substantial cloud breaks developing during the day than currently anticipated. Muddled forecast for next week as strong upper level low and energy comes out of the Gulf of Alaska moves through the northern Rockies early next week and mostly loses it`s eastern push/momentum. Southeast Michigan loses to be caught in between the building upper level trough over the southeastern U.S. and the series of height falls tracking through the Midwest and upper Mississippi River Valley. Higher confidence in temperatures ending up solidly above normal. Low confidence in rain and thunderstorm chances. MARINE... A low pressure system will travel north across the western Midwest today, settling over western Lake Superior by tomorrow night. This will push a stalled frontal boundary, which is currently draped over central Michigan, north into the northern Great Lakes. Rain and some rumbles of thunder remain likely along this frontal boundary through early tomorrow morning. The position of the low will also reinforce northeast flow across the Great Lakes through tomorrow morning, bringing elevated wave heights across the Saginaw Bay to Harbor Beach, where Small Craft Advisories are in effect. A very shallow mixing layer is expected to develop tomorrow morning across north to north-central Lake Huron which will allow for some localized higher wind gust potential with flow coming from the northeast. Gusts around 30 to 35 knots will be likely, centered between 10Z to 20Z. Was on the fence with the issuance of a Gale Warning, but confidence remains low whether gale potential will persist in any given three hour window, especially if the marine layer is more stable relative to modeled sounding projections. A short fused Gale Warning will still be considered for future updates if model trends suggest higher probabilities for gale potential. Otherwise, shower and storm potential will increase for all locations tomorrow afternoon and evening, ahead of a cold front. Thunderstorms will have the potential to produce isolated gusts to or above 30 knots. HYDROLOGY... Scattered-numerous showers and thunderstorms will remain mainly north of M-59 through tonight as a frontal boundary holds steady through this evening before lifting north by Monday morning. Another round of numerous showers and scattered thunderstorms are expected across all of southeast Michigan Monday afternoon as cold front tracks through. Additional rainfall this evening through tomorrow evening looks to average around half an inch across most locations, but any stronger thunderstorms will push totals to at or above 1 inch. While significant flooding is not expected at this time, minor flooding in prone urban and poor drainage areas is possible, with notable rises in area rivers. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...Small Craft Advisory from 11 PM this evening to 4 PM EDT Monday for LHZ421-441. Small Craft Advisory until 10 AM EDT Monday for LHZ422. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....SC DISCUSSION...SF MARINE.......SF HYDROLOGY....SF You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.