Sunrise 5:55 AM   Sunset 7:57 PM Moonrise 8:09 PM   Moonset 5:04 AM

  Print   HELP   Reset   Save   Recall

FXUS63 KGRB 240325 AFDGRB

Area Forecast Discussion National Weather Service Green Bay WI 1025 PM CDT Tue Apr 23 2024

Updated aviation portion for 06Z TAF issuance

KEY MESSAGES

- Elevated fire weather conditions are likely Wednesday and Thursday due to relative humidities ranging from 15 to 25 percent. However, relatively light winds and cool temperatures will keep conditions below critical levels.

- Two systems will bring periods of showers and thunderstorms to the forecast area Friday through Monday. Watching the potential for severe weather on Saturday, although it is still too soon to tell.

DISCUSSION
Issued at 224 PM CDT Tue Apr 23 2024

Short Term...Tonight and Wednesday

The latest RAP analysis and satellite/radar imagery show a dynamic upper trough moving across the western Great Lakes early this afternoon. The trailing cold front is entering far northern Wisconsin. Showers and thunderstorms developed by late morning across north-central and far northeast Wisconsin and continued to expand in coverage into the early afternoon hours as temps reached their convective temps. Due to deep mixing (estimated at up to 600mb!!), the showers were high based and produced gusty winds upwards of 40 mph. Have not received any reports of hail, but storms in the Upper Peninsula produced three quarters inch hail.

The showers and storms will continue to move southeast for the rest of the afternoon. Even light showers will be capable of producing gusty winds to 40 mph as the lower atmosphere will be supportive of evaporative cooling. Small hail will also be possible in the strongest storms, but this threat is will be more confined to central and east-central WI where precip has been more widely scattered.

Clouds and precipitation: Showers and a few storms will rapidly exit east- central Wisconsin this evening. Gusty winds and small hail will be possible but the threat should wane rapidly as nocturnal cooling sets in. Most showers will exit by the 8-9 pm hour.

Then a very dry airmass (pwats 20-30% of normal) will move into the region from the north for the rest of the night. After a period of mostly cloudy skies behind the front, skies should rapidly clear late this evening into overnight. Clear skies are then expected for Wednesday.

Temperatures: No significant changes to the previous forecast.
Don't think winds will fully decouple tonight, so remained close the NBM. On Wednesday, low level temps are colder over eastern WI due to north winds and the previous forecast already showed this well.

Long Term...Wednesday Night Through Tuesday

An active pattern is expected to set up toward the end of the work week and persist through early next week. Multiple chances for rain and thunderstorms will accompany several systems that are progged to track from the central Plains into the upper Midwest through Monday. Watching potential for severe weather on Saturday, although currently too far out in the forecast period to discern any details. Temperatures will begin a steady incline through the end of the week before peaking in the mid 70s (~15 degrees above average) on Saturday given favorable placement in the warm sector.

Friday/Saturday precip... Main focus for the extended is an end of week system that will bring rain and storm chances to the forecast area, including potential for some severe weather on Saturday. A robust upper-level shortwave will spin up a surface low over the central Plains before trekking into the upper Mississippi Valley Saturday morning. Current model guidance seems to be targeting portions of northeast Wisconsin to receive the bulk of the QPF (~0.6 to 1") from this system, although there is still some disagreement about when precip arrives on Friday. Suspect that QPF may trend on the higher end of what ensembles are currently showing given deep Gulf moisture placing around 1.3" PWATs across most of eastern Wisconsin. Some elevated storms would be possible Friday afternoon/evening out ahead of the warm front, although most convective elements look to come together on Saturday. A trailing cold front is progged to move east across the warm sector during peak heating Saturday afternoon, providing a source of lift for surface-based convection. Additional ingredients (CAPE, lapse rates, shear) also look to be in relatively good shape for Saturday, although it is still too soon to tell for certain.
Southeast winds will begin to ramp up Friday afternoon as the pressure gradient tightens between the leading edge of the approaching surface low and departing high pressure to the east.

Sunday/Monday precip... A brief lull in precip is expected to set in Saturday night to Sunday morning before a second system trails from the Four Corners region into the upper Midwest by Monday morning. There are still timing issues this far out in the forecast period, although there is a strong signal for periods of moderate to heavy rainfall across northeast Wisconsin.
Thunderstorms look to be possible across eastern Wisconsin Monday afternoon, although this could change as models hone in on timing.

AVIATION
for 06Z TAF Issuance Issued at 1018 PM CDT Tue Apr 23 2024

MVFR ceilings still covered a large portion of the forecast area late this evening. The low clouds should erode early in the TAF period, except along the lakeshore, where they may persist until daybreak.

Canadian high pressure will bring clear skies and light and variable winds to the region for most of Wednesday and Wednesday evening.

FIRE WEATHER
Issued at 224 PM CDT Tue Apr 23 2024

Another period of elevated fire weather conditions is likely on Wednesday and Thursday due to a very dry airmass that will move into the region. Afternoon RH values of 15 to 30 percent are likely on Wednesday, but cooler temps are anticipated in the lower 40s lakeside to the low 50s inland. On Thursday, RH values will be slightly higher between 25 to 35 percent, but temps and winds will both be slightly higher. While RH's will be near to below critical criteria, winds and temps should remain below criteria each day.

GRB WATCHES/WARNINGS/ADVISORIES
None.

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

Green Bay, WI,