Area Forecast Discussion
Issued by NWS Gaylord, MI
Issued by NWS Gaylord, 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
48
49
50
241 FXUS63 KAPX 080345 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 1145 PM EDT Sun Jul 7 2024 .KEY MESSAGES... - Scattered showers and thunderstorms Monday and Tuesday - Uncertainty, in regards to rain, midweek. && .UPDATE... Issued at 1013 PM EDT Sun Jul 7 2024 Upstream cold front has reached the far Western Great Lakes region late this evening. Aside from a few isold pop-up showers that briefly develop along lake breeze boundaries during peak heating...our CWA has remained largely dry thru the day and this evening due to limited instability and weak wind fields. Near term models still point toward increasing low level moisture overnight thru Monday as the cold front edges closer to our CWA. Also expect some increase in instability along and ahead of the front. Thus...still expect a gradual increase in chances of showers and storms overnight and Monday...with the best chances developing Monday afternoon/evening as peak heating adds to an increasingly unstable airmass. Do not expect any strong/severe storms overnight due to weak wind fields and very limited instability. Overnight lows will cool into the upper 50s and lower 60s. && .SHORT TERM /THROUGH MONDAY/... Issued at 246 PM EDT Sun Jul 7 2024 Pattern Synopsis and Forecast: Upper level troughing currently resides over the northern plains, stretching down to the central plains. Cooler air near the surface is making its way southward over the Dakotas this afternoon, with the cold front moving over MN/IA. This results in SW winds aloft over MI, carrying the warm sector north. Satellite depicts storms forming along a weak boundary ahead of the front over SE WI, north of Chicago. This weak boundary will move up towards northern lower tonight, being carried by SW winds through the column ahead of the approaching trough. Chances for showers will spread out over northern lower tonight into early Monday morning with embedded thunder possible. Winds turn mostly south to southwest Monday morning skies remain mostly cloudy. Isolated to scattered showers and storms will be seen Monday midday through the evening hours. Primary Forecast Concerns: Soupy air will move into the region tonight ahead of an approaching upper trough. Surface dew points rise into the mid to high 60s with PW values around 1.5" by Monday morning. Soundings show much of the moisture being below 500mb. Instability is limited to around 1000 j/kg (MU & SB), and trailing off in the HGZ. Convective T is in the high 70s low 80s around the CWA, which we will likely reach in most places especially if the sun can poke through. Surface winds remain weaker as the front remains to the west. This results in 0-1km shear around 10 to 15kts, with ~ 30kts of 0-6km which sets up an environment capable of producing storms that can become organized, but limited shear exists for rotation near the surface. This all supports a scenario of scattered showers and storms Monday afternoon with a few being capable of producing torrential rainfall and damaging winds. Small hail could also be seen (and maybe a quarter could sneak by) with freezing levels around 10 - 11 kft. HREF guidance shows chances for LCL heights to drop to 1000ft (or even slightly below), which when paired with the possibilities of locally enhanced wind shear a tornado can`t be ruled out but chances remain low. Recent rains have left most places with saturated soils, leading to flashy responses of water with torrential rainfall. Sandy and saturated soils leave trees more vulnerable to downburst winds from thunderstorms. Storms Monday afternoon have the potential to produce these winds and heavy rain, which could lead to trees down and urban and small stream flooding. Make sure you stay up to date with the latest forecasts and warnings. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... Issued at 246 PM EDT Sun Jul 7 2024 Pattern Synopsis and Forecast: Very blocky, slow moving/evolving upper pattern across the CONUS- portions of North America this upcoming week. Large ridge across West Coast into western Canada (hence all the heat across CA-PAcNW), and ridging across eastern seaboard as well to an extent. Weak trough across the center of the county will eventually capture Beryl, or the remnants, mid week and slowly move northeast/wash out into the prevailing flow aloft. Where this happens, and subsequent sfc low actually tracks will be all the difference and is uncertain at this time. Heights are expected to rise thereafter in the extended range next weekend resulting in warming temperatures. Primary Forecast Concerns: Troughing/lowering heights will be hanging around Monday night, thus scattered showers and lingering thunderstorms likely early in the evening. Temperatures warm aloft/lapse rates (whatever the antonym of steepen here that flows well with the sentence), thus instability will be weaker on Tuesday compared to Monday. In addition, source of lift aloft largely weakens. Instability mainly remains confined to eastern shores near Lake Huron and vicinity-southeast of there, thus POPs reflect this in the forecast, with isolated to scattered afternoon general thunderstorms. Weak, skinny instability and modest shear will limit any appreciable severe threat. Attention turns to tropical remnants, and really just the low pressure and associated moisture, on Wednesday into Thursday. As kind of expected, uncertainty remains in regards to impacts from this feature, if any at all. Latest deterministic guidance seems to shove the low pressure largely to the east of the region as an upper trough "captures" this feature to the east of N MI. Ensembles show a wide range of solutions from little to no impact, to lots of rain (current GEFS 12Z guidance has a noticeable shift southeast). Perhaps joining the dark side a little bit here, ECMWF AI model bring this feature right up into MI, GFS AI farther southeast. Furthermore, the ICON model, which has handled this feature as Beryl exceptionally well to this point, skirts southeastern portions of northern lower Michigan at this time. All this to say, the exact interaction of the upper trough and the sfc feature will be key and thus we remain in monitoring phase at this point. Based on some shallow intuition here, think the most likely outcome will be the south and eastern portions of the area to have the best chance for seeing any appreciable rains Wednesday-Thursday, but confidence in any outcome is very low at this time. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1145 PM EDT Sun Jul 7 2024 Low level moisture and instability will gradually increase overnight thru Monday night in advance of an approaching cold front... resulting in increasing chances of showers and thunderstorms. Best chances of convection will develop Monday afternoon/evening as peak heating adds to an increasingly unstable airmass. Prevailing conditions will remain VFR but will occasionally drop to MVFR/possibly IFR within heavier showers/storms. SE winds under 10 kts overnight into Monday morning will shift to the S/SW Monday afternoon. && .APX WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ UPDATE...MLR SHORT TERM...ELD LONG TERM...JLD AVIATION...MLR