textproduct: La Crosse
This forecast discussion was created in the public domain by the National Weather Service. It can be found in its original form here.
KEY MESSAGES
- More rounds of rain expected to start the work week. Some areas could see a multi day total of 2 to 3 inches.
- After a dry end to the work week, another round of rain returns for next weekend. Otherwise, temperatures remain closer to seasonal for mid week into the weekend.
DISCUSSION
Issued at 237 PM CST Sun Nov 3 2024
Tonight - Tuesday Night: Periods of Showers Continue
Bulk of weather in the short term will be defined by short waves ejecting northward out of large western trough. While it may be difficult to determine exact timing between precipitation, there certainly appears to be periods with higher rain chances.
Forcing associated with first short wave has led to broad area of isentropic lift as abnormally moist air lifts north over a frontal boundary to the south. After one area of rain moved through overnight, a second is impacting the area this afternoon. Bigger question may be the extent of rain or showers tonight with hints of another short wave on the heels of the current one. Moisture advection and higher precipitable water axis seems to be peaking this afternoon though so rain tonight could be a bit more spotty. May hold rain threats down for a time this evening /30-40%/, would not be surprised if activity increases overnight or early Monday morning.
A parent upper level trough then moves in towards the region Monday night into Tuesday, with an accompanying surface cold front moving through and surface low lifting along the baroclinic zone. Attendant lift/forcing along with another surge of moisture looks to allow for additional rain chances through this period. However, as the previous discussion alluded to, the challenge is where the band of heaviest rainfall sets up. The 03.12 HREF ensemble probability matched-means would suggest that this band remains further south and east into Illinois and south/southeast WI. This trend has been reflected in the latest QPF forecast, and with some variability among models on overall rainfall coverage, expecting that there will continue to be refinements in the following forecasts. Models also suggest additional rainfall in the deformation zone early Tuesday, though there remain some differences between GEFS/ECMWF ens on amounts with the GEFS remaining the perkier of the guidance.
Overall, could see another storm total band in the 2 to 3 inch range across parts of northeast Iowa into southwest Wisconsin. Hydrologic models via the River Forecast Center have some of these basins possibly reaching action stages so will have to start monitoring this a bit closer.
Wednesday - Next Weekend: Dry mid to late week, then another round of rain for the weekend.
Surface high pressure builds into the region with dry conditions forecast for the mid to late work week. Ensemble guidance then shows an upper level trough/low shifting eastward from the Four Corners, eventually moving across the region next Sunday. The ECMWF ens seem to be fairly consistent with the progression of this system, whereas the GEFS has shown some variability among runs. This will have some implications on the onset timing of our next precipitation chances across the area. The latest NBM PoP field continues to reflect a slightly slower trend with chances overall increasing into the day Saturday. Unlike the preceding rainfall events, no strong moisture anomaly signals with this system. In turn, GEFS/ECMWF 24-hr QPF would suggest only 10-40% for greater than or equal to 0.5".
Otherwise, temperatures remain fairly consistent with highs in the 50s and lows in the 30s to low 40s from mid week through the weekend.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
Issued at 555 PM CST Sun Nov 3 2024
IFR/LIFR conditions are expected through the TAF period outside of ongoing MVFR conditions at KLSE for the next couple of hours. Generally, precipitation has exited the region although some light drizzle may accompany some low-level saturation over the next few hours. Heading into the overnight, the aforementioned low-level saturation coupled with recent rainfall will aid in fog/low-stratus formation with the 03.22z NBH having very high probabilities of IFR (70-90%) overnight at both KLSE and KRST. Will have to watch how low vsbys get as the 23.18z HREF has some lower probabilities (20-40%) of 1/4SM at KRST. However have opted to hold off on lower vsby mention for now. Additional showers will likely move through the region tomorrow however hard to pin down any shower activity outside of a wave that moves through during the morning hours. Towards the afternoon and evening hours a frontal passage will shift winds to northwesterly and instigate some showers along it as shown in recent CAMs guidance. As a result, have included a prob30 at KLSE for this potential during the late afternoon on Monday.
ARX WATCHES/WARNINGS/ADVISORIES
WI...None. MN...None. IA...None.
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