Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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
727 FXUS63 KDLH 191006 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 506 AM CDT Sun May 19 2024 .KEY MESSAGES... - Our next chance of precipitation moves in tonight through Monday. A few mainly elevated thunderstorms may bring locally heavy rainfall. - Slight Risk >15% for severe storms on Tuesday as a rapidly deepening low pressure system moves toward and across the Northland Tuesday through Wednesday. - The active weather pattern continues through next weekend with precipitation chances returning for Friday through Saturday. && .DISCUSSION... Issued at 504 AM CDT Sun May 19 2024 Today should be a generally quiet and warm day, with high temperatures generally in the 70s. Cooler than yesterday, but we will have a gradual increase in clouds through the day, a cooler start this morning and shallower mixing. We will have some warm air advection that sets in aloft which is likely to help those clouds increase and bring some virga showers into the area this afternoon. However, the very dry low level RH values will help delay the arrival of precipitation that reaches the ground until much later this afternoon or even tonight. Have included some sprinkles for today in advance of the main wave of precipitation. This is being driven by a weak shortwave in combination with a surge of moisture and an inverted trough at the surface. This system should bring us at least some light precipitation over a large portion of the Northland, along with a 75% probability or greater of getting a quarter inch or more over northwest Wisconsin. Once this band of precipitation moves through on Monday, we should get a short break in the active weather Monday night. Tuesday into Wednesday is the time frame we are most concerned with, as a much stronger upper level shortwave pulls out of the Rockies and develops a surface low over western Kansas Monday night which drives northeast across the western Great Lakes Tuesday night. This much stronger system will combine with another surge of Gulf moisture to produce a period of very busy weather for the Northland Tuesday through Wednesday. Tuesday evening we should develop a narrow window of instability with sufficient shear to produce strong to severe storms Tuesday afternoon and evening, mainly over northwest Wisconsin. SPC has put us into a slight risk of severe weather on the day 3 outlook, which is well supported by what I see in the model guidance this morning. This system is also likely to generate generous rainfall amounts with that Gulf moisture feed, and the GFS is showing precipitable water values of over 1.25", which is over the 90th percentile, almost to the climatological max for this date. WPC has put us into a slight risk of excessive rainfall, and we will have to watch for localized flooding issues Tuesday night into Wednesday. This system exits the area Wendesday night, leaving us with some lingering shower activity into Thursday. We are also looking at some much cooler temperatures for Wednesday into Thursday, with highs both days down into the 50s to low 60s. We get only a short break in the active weather Thursday before it appears we get another upper level shortwave that moves across the Upper Midwest through the end of the work week into next weekend. Models are still showing some pretty large variations in timing, track and strength of this system, so can not say much more than we have precipitation chances through this time frame with warmer temperatures on Friday followed by a cool down into the weekend. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1244 AM CDT Sun May 19 2024 VFR conditions are expected this TAF period. southwest winds of less than 10 kts overnight will pick up to 10-15 kts in the 15z-21z time frame Sunday, then decrease again after 22z. A low pressure system will push high clouds into the area from the west on Sunday, with cloud bases slowly lowering through the day. Showers will begin to affect the terminals around 00z, but conditions will remain VFR. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 504 AM CDT Sun May 19 2024 Southwest winds will gradually increase over the lake today, with gusts of 25knots for several hours. This will cause conditions hazardous for Small Craft from late morning through the early evening for the North Shore north of Grand Marais. The winds will decrease once again this evening, then gradually back into the southeast overnight tonight. Monday winds will become northeast as a low pressure system approaches the area, but generally remain in the 10 to 15 knot range through Monday and Monday night. Winds begin a gradual increase on Tuesdsay as another low pressure system approaches and then moves across the area through Wednesday. It looks like we will need another Small Craft Advisory for much of the lake, with a small risk of gales Tuesday night into Wednesday. For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt. && .DLH WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. MARINE...Small Craft Advisory from 10 AM this morning to 6 PM CDT this evening for LSZ140. && $$ DISCUSSION...LE AVIATION...LE MARINE...LE