textproduct: Hastings

KEY MESSAGES

- Areas of dense fog and patchy drizzle/freezing drizzle this morning.

- At least one more round of dense fog possible tonight, though perhaps not as widespread as recent nights.

- Warmer, mainly dry, and sunnier this weekend.

- Colder and next chance for snow (light accumulations?) Monday into Monday night.

DISCUSSION

Issued at 430 AM CST Thu Dec 26 2024

It took a bit longer than expected...and it's not quite as widespread as previous nights...but dense fog has steadily returned early this morning. Most sites are now reporting 1/4-1/2 mi visibility, with a few sites on mainly the far NW and SE edges reporting higher values. Very weak warm air advection and persistent cloud cover (limiting outgoing longwave radiation) has allowed for warmer temperatures early this morning compared to 24 hours ago, with all but the NW 1/4 of the CWA reporting temps above freezing. And even the "colder" areas have experienced steady or slowly rising temps recently. This is important bc radar trends and observations show patchy/scattered areas of light drizzle have floated through the area...and model soundings suggest this potential will continue through at least the AM hrs today. Fortunately, I think the persistent wet conditions have spared us greater impacts as drizzle on top of wet surfaces at 32F is far different than new drizzle occurring on dry surfaces at temps 28-30F (Thank you specific heat content of H2O!) Given lack of reported impacts thus far, think it's unlikely we'll see a significant deterioration over the coming hours as temps should continue to slowly rise. Thus, think the ongoing Dense Fog Advisory with mention of localized slick spots will be sufficient messaging. Whatever weak boundary layer lift is out there should shift off to the E this aftn with the weak inverted trough axis, so suspect we'll transition back to mainly mist/fog for the evening and overnight hrs.

Speaking of fog, 06Z HRRR and latest SREF both indicate high potential for dense fog to return once again this evening around/shortly after sunset. Heck, some localized spots of dense fog may never dissipate at all today, esp. from around Alma to GI. Nonetheless, appears yet another Dense Fog Advisory will be needed again tonight, but this COULD be the last one of this stretch. Models graze the far S/SE/E portions of the area with more lgt drizzle and/or lgt shwrs on Fri, but after that, and swing in direction to more of a Wrly component within the boundary layer should make dense fog formation more difficult Fri night into Sat AM...esp. W 2/3rds of forecast area. Will have to watch Hwy 81 corridor for perhaps patchy fog early in the evening.

The Wrly low level flow, combined with much more sunshine, should allow for temps to warm nicely this weekend. Guidance remains consistent that highs should climb into the 50s area wide Saturday and Sunday. May even see some low 60s from around Beaver City to Osborne Sun aftn.

Shortwave ridging from the weekend will transition to fast NWrly flow for early next week, lead by a potent, but quick-moving clipper system. Timing is still largely in the Mon-Mon eve time frame, and the general track and magnitude of preceding warmth suggests initial activity will probably be more liquid than frozen. However, as colder air filters in throughout the day, should see the rain changeover to snow, particularly for areas of south central Nebraska N of Hwy 6/I-80. Still some model differences regarding exact track, which will be key in determining location of main axis of lgt snow accums, but ensemble output seems to indicate we may be converging towards idea that primary swath will focus across N portions of Nebraska. Obviously, this would present greatest risks for light accums locally to be mainly N of I-80...with much lesser risks for north central KS. Still some time for the system to nudge N or S, but main message at this point is that wintry travel impacts may return to particularly N half of the forecast area on Mon, with the brunt of travel impacts focusing more towards Mon eve/night as opposed to Mon AM.

Cooler NW upper flow looks to persist much of next week, but the magnitude of cold is still to be determined - partly by the location of any new snow cover, but also by the location/orientation of the primary trough/ridge axis within gradually amplifying upper flow. Could be a pattern that exhibits sharp temp gradients from E IA to the High Plains. Latest TRENDS have been for the extended periods to be not as cold as once indicated - which has kind of been the pattern of this winter thus far, and is a classic "calling card" of a broader La Nina winter. With Monday's system seemingly more of narrow and one and done for the week type of snow event, and some downsloping component to low level flow possible by late in the week, the possibilities for near to above normal temps by late week have some merit.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 538 AM CST Thu Dec 26 2024

For KGRI/KEAR Airports:

Significant weather: LIFR CIGs all period, IFR to LIFR most of the period.

Today: LIFR CIGs/VSBYs, at or below airport mins, will persist most of the morning. VSBYs should see some improvement back to IFR or MVFR (MAYBE briefly VFR 20-22Z) this aftn, but CIGs are likely to remain LIFR at 300-500ft all day. Winds will be vrbl or Srly at 4-7kt. Confidence: High.

Tonight: LIFR CIGs near airport mins again tonight. VSBYs are likely to drop again this evening around sunset, back to IFR or LIFR by ~02Z, and continue all night. Winds will be Srly 5-8kt. Confidence: CIGs - high, VSBYs - medium.

GID WATCHES/WARNINGS/ADVISORIES

NE...Dense Fog Advisory until noon CST today for NEZ039>041-046>049- 060>064-072>077-082>087. KS...Dense Fog Advisory until noon CST today for KSZ005>007-017>019.