![National Oceanic and Atmospheric Administration](/build/images/header/noaa.d87e0251.png)
![National Weather Service](/build/images/header/nws.4e6585d8.png)
![United States Department of Commerce](/build/images/header/doc.b38ba91a.png)
Area Forecast Discussion
Issued by NWS Twin Cities, MN
Issued by NWS Twin Cities, 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
679 FXUS63 KMPX 132314 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 614 PM CDT Tue Aug 13 2024 .KEY MESSAGES... - Our dry period ends tomorrow with widespread showers expected to gradually spread west to east tomorrow. The heaviest rain is expected tomorrow evening through early Thursday morning. - Lingering showers are possible Friday & Saturday before we resume our dry and mild stretch by Sunday. && .DISCUSSION... Issued at 252 PM CDT Tue Aug 13 2024 A broad cumulus field has blossomed over the northern plains this afternoon with cumulus evident from southern Canada all the way south through Illinois, Indiana, and Ohio including most of Minnesota & Wisconsin. There are some high clouds moving through southwestern Minnesota as well evident on GOES satellite imagery, with a small chance for a few pop showers much like yesterday in southwestern Minnesota. Light southerly to southeasterly winds continue ahead of the incoming system which will bring showers back to the region tomorrow, alongside a northwesterly wind shift that looks to persist through the next several days. The impetus for initial showers arriving in western Minnesota as early as sunrise tomorrow is a strengthening low level jet bringing an influx of moisture and warmth to force showers as the leading edge of a trough begins to slide eastwards over the northern CONUS Rockies. This jet will continue to pump gulf stream moisture northwards allowing for increasing PWATS into the 1.7-1.9 range which is already a couple tenths of an inch above the 90th percentile for August 14th. A series of shortwave impulses are expected to spread eastwards from the approaching trough which should couple with the jet forcing to produce a large swath of showers and potential storms which will gradually move west to east across Minnesota and into Wisconsin tomorrow. Model guidance has a bit of spread in regards to timing and amount of precipitation with the CAMs favoring a slower onset time and less overall precipitation compared to the medium to long range global models, with significant spread in the GEFS in regards to both total amount of rainfall and the timing. The GEFS mean for MSP would produce an inch and a half of rainfall through 7pm Thursday with a lack of consensus within guidance as most membership spreads from a few tenths to as much as 2 inches. The higher amounts would be possible during the heaviest rainfall which looks to be late tomorrow through around 5-6am Thursday as the low level jet once again strengthens and amplifies the forcing from the trough. The surface response is fairly muted with a surface low only forming as the trough axis swings through by midday Thursday. Overall, expect most of the area to pick up anywhere from 3/4 of an inch to around an inch and a half of rain over a 36 hour period from when precipitation enters the region tomorrow through Thursday. Taking a deeper dive into severe weather parameters, there is also quite a bit of spread in potential as the higher pwats and fairly saturated moisture profile would support heavy rain but only weak storms, especially overnight. As CAM guidance has trended slower than global guidance, the best chance for stronger storms would be near sunrise Thursday with a strong low level jet present alongside increasing instability. As of right now, the main threat would be heavy rain producing outflow or micro-burst type winds, with that threat looking on the lower end of things for now. As the upper level system rotates over the Great Lakes heading into the weekend, further light showers are possible as both aloft and surface winds shift northwesterly, with cold air advection showers possible until the system rotates out further by Sunday. Once we get through Saturday, the rest of the forecast looks dry and a return to what we have been seeing the last week or so, which is mild temperatures and dry weather. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 614 PM CDT Tue Aug 13 2024 Continued VFR and light winds tonight. Fog will again be possible, but should not be as widespread as the previous morning. Confidence in the fog is low enough that no fog was included in the TAFs. It however is possible and we will be monitoring trends tonight for possible TAF updates. The main focus of these TAFs will be the rain tomorrow. This rain will move in from southwest to northeast. As rain starts, a drop to MVFR is expected and eventually some IFR is expected as well. The coverage of IFR is still uncertain, so did not include IFR in the TAFs at this point. Rain chances will continue past the end of the current TAFs. As we get closer additional details will be added with additional timing adjustments and details on flight categories. KMSP...Continued light winds and VFR into tonight. Tomorrow will be a different story. Still uncertainty on when the rain will arrive so opted to go for a PROB30 when the earliest time the rain could start with the prevailing group going to showers when it is most likely to start. Winds will also become gusty in the afternoon before calming some by the evening. /OUTLOOK FOR KMSP/ THU...MVFR/IFR, -SHRA/-TSRA. Wind E to NW 10-15 kts. FRI...VFR, chc MVFR/-SHRA. Wind NW 10-20 kts. SAT...VFR, chc MVFR/-SHRA. Wind NW 5-15 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ DISCUSSION...TDH AVIATION...NDC