textproduct: Aberdeen

KEY MESSAGES

- Fog is expected to diminish some later today before returning again tonight into Friday morning. Some of the fog this morning could still become locally dense with visibility dropping to a quarter mile or less. A Dense Fog Advisory remains in effect for parts of east central South Dakota this morning.

- Very light precipitation (~20% chance for moisture) potential will move from west to east toward eastern SD/western MN late Friday. A mix of precipitation types (mainly either very light rain or very light freezing rain) is possible. If road surfaces fail to warm above freezing, travel may be impacted.

- Temperatures will run around 10 to 20 degrees above normal from today through Sunday, before cooling to something closer to normal at the beginning of next week, persisting into the new year.

- There is currently around a 40% chance of an inch of snow Monday across central South Dakota.

UPDATE

Issued at 521 AM CST Thu Dec 26 2024

See below for an aviation forecast discussion for the 12Z TAFs.

SHORT TERM /TODAY THROUGH FRIDAY AFTERNOON/

Issued at 329 AM CST Thu Dec 26 2024

At 3 AM CST, west of the James River valley, skies are generally partly to mostly clear with temperatures having cooled into the low to mid 20s for the most part, despite a west-component boundary layer wind direction (generally 5 to 10 mph). Across and east of the James River valley, skies are overcast, with some light fog ongoing over the Prairie Coteau/Sisseton Hills region of the CWA. Temperatures under the cloudy sky condition have remained in the upper 20s to lower 30s on south winds 10 to 20 mph with some occasionally higher gusts.

There is a pretty active polar jet stream happening out across the western CONUS this morning. Over this region, the upper flow remains rather weak and baggy. The surface trof that has worked about half- way through the CWA will fade away today, as upper level heights begin to rise a little bit. With no end in sight to the notable low- level thermal inversion and all the low level moisture trapped under it, expect stratus clouds and fog potential to persist. Continuing, for the moment, with a dense fog advisory over the southeast-most counties of the CWA, based on potential for vsbys to tank by sunrise this morning. Vsbys right now are not that bad across the southeastern zones. Collaborated the continuation of the advisory, though, in case vsbys do end up tanking within the next few hours. There may be some improvement in vsbys/fog and cloud-cover over the eastern half of the CWA during the day today, but with plenty of low level moisture around again tonight under a still quite strong low level thermal inversion (see 00Z KABR RAOB) on light south- southeasterly surface winds, there is yet another night of potential fog/low clouds to contend with.

Will have to wait and see if the energy that is progged to move over the region on Friday (and its associated surface trof) will be strong enough to force a west-component surface wind/surface trof all the way across the CWA into Minnesota. If this is able to happen, the low level moisture and thermal inversion should be thwarted, for awhile anyway. There are still some ensemble-based (mainly hi-res CAM) 20-ish PoPs hanging around heading into Friday morning, working from west to east over the CWA. P-type, should any precipitation be generated and able to reach the ground, is expected to either be rain or freezing rain. But, again, qpf guidance at this time is "non-measurable" for this potential event, meaning not all that concerned just now if an hour or two of very light freezing rain Friday morning happens, and is chased away by temperatures warming to above freezing.

The CWA is still forecast to reside on the warm air side of things through the short term, so both high and low temperatures today through Friday should continue to be about 10 to 20 degrees above normal.

LONG TERM /FRIDAY EVENING THROUGH WEDNESDAY/

Issued at 329 AM CST Thu Dec 26 2024

Chances for precipitation Friday night into Saturday currently look to stay to the east, and the ABR forecast area now has PoPs of less than 15% across the entire area. The bigger overnight impact will come in the form of the persistence of the low-level moisture that has been occupying the region the last few nights giving the area patchy fog. This low-level moisture should finally move out of the region on Saturday, taking away the fog and low cloud decks.

Temperatures Saturday and Sunday are forecasted to run 10-20 degrees above normal (with the exception of areas covered by fog on Saturday). Forecasted highs of upper 30s to upper 40s will most likely be in the top 10 on record, but still well shy of the top spot (upper 50s to low 60s at the five climate sites). Temperatures are set to return to normal or just above normal on Monday.

We continue to keep our eye on Monday's system, when precipitation on the north side of a low pressure center is set to impact southern South Dakota. A slight shift north in the track of the low pressure center has increased probabilities of measurable precipitation over central South Dakota to approximately 40-50%. Probabilities fall off traveling further north, but the entire forecast area will now have at least a 10% chance. QPF 25th-75th spread for this event is around 0-0.15" for central South Dakota, which while not particularly large, still offers some room for some decent variability. Moisture aloft looks to be enough to saturate a large portion of the profile from the DGZ and above. With temperatures below freezing through the profile and surface temperatures mainly set to be below freezing, snow is most likely the main precipitation type here. Given the 90th percentile QPF up to 0.25", a reasonable "worst case scenario" for this event is 2-3" over central South Dakota. However, ~1" is currently the most likely outcome.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 521 AM CST Thu Dec 26 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will prevail today at KPIR, KMBG and KABR. KATY is expected to experience IFR/LIFR condition from both low cigs and vsbys through 18Z today. Between 18Z and 00Z, KATY may see vsby improve, but the low cig is likely to remain. Later tonight, both KATY and KABR could see fog/low stratus forming at/near the terminal.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Dense Fog Advisory until noon CST today for SDZ019-020-022-023.

MN...None.