Area Forecast Discussion
Issued by NWS Aberdeen, SD
Issued by NWS Aberdeen, SD
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467 FXUS63 KABR 101736 AAC AFDABR Area Forecast Discussion...UPDATED National Weather Service Aberdeen SD 1236 PM CDT Sat Aug 10 2024 .KEY MESSAGES... - Temperatures will continue from 5 to 15 degrees below average through the weekend. - There is a 40-65% chance of showers and thunderstorms Sunday through early Monday, with the highest chances of precipitation over central South Dakota. - A general warming trend is expected with seasonal/near average temperatures for the later half of next week. Weak systems next week will provide for off and on chances for moisture. && .UPDATE... Issued at 1234 PM CDT Sat Aug 10 2024 See below for an aviation forecast discussion for the 18Z TAFs. UPDATE Issued at 1013 AM CDT Sat Aug 10 2024 No changes planned to the today period forecast. && .SHORT TERM /TODAY THROUGH SUNDAY AFTERNOON/... Issued at 233 AM CDT Sat Aug 10 2024 As of 2am overall skies remain clear with some mid to high clouds passing over central SD. Temps are ranging in the upper 40s to the lower 50s. Short term models indicate northwest flow over the Northern Plains as the large low continues to push east/northeast. The center of the low is forecasted be over eastern Ontario/western Quebec by early Sunday morning. The low amplitude ridge out west will also break down Sunday, with winds turning more zonal/northwest, as shortwaves move in over the Northern Rockies Sunday morning. These waves will push east and over the Northern Plains through the day. At the surface, a high pressure still remains dominant which will keep the area dry for today. This high shifts a bit east for Sunday with the incoming waves. 850mb winds become southeasterly early Sunday morning, ushering in WAA and an increase in moisture, seen on RAP 1000-500mb RH over north to south central SD. With aid from the shortwaves, HREF/RAP indicates elevated showers and thunderstorms moving into this area during this time. CAMs seem to show this but there are some differences between the models on timing/location as they enter our western CWA. Precipitation will spread eastward through Sunday afternoon over central and parts of northeastern SD. Pops range from 30-65%, highest over south central SD. Instability looks to remain low as MUCAPE values will be under 1000 j/kg over central SD, however, 2-5km UH>75m2s2 indicates the possibility of some stronger cells skirting our southwestern CWA Sunday afternoon as shear will increase to 30-40kts in this area. Lapse rates will be marginal and these are the HRW models showing this and may be a bit aggressive. With east to southeast flow over central SD today, temps will be warmer at 850mb, around 15-16C in this area, with cooler temps (from high) over our eastern CWA ranging from 9-13C. Surface highs are forecasted to range in the 70s to possibly 80, warmest around and west river. With WAA continuing tonight, lows will not get as chilly, ranging in the 50s (few upper 40 readings possible along ND/SD border). Highs for Sunday will again range in the 70s but will be cooler over the western CWA than today due to cloud cover. && .LONG TERM /SUNDAY EVENING THROUGH FRIDAY/... Issued at 233 AM CDT Sat Aug 10 2024 Upper flow pattern has us in between two weak troughs through most of the extended. Late week, deterministic members diverge in handling how the upper trough to the west migrates into the center of the country, so will focus in the interim. Monday through Thursday we will have a ridge aloft, though with several weak waves migrating through the flow. In the low levels, the broad expanse of the high pressure continues to dominate the Midwest with easterly low level flow off that high keeping us mild with relatively/seasonally low dewpoints. We do see a weak low level jet slowly pulling 850mb moisture northwards, but this round of the GFS shows a much less organized plume with a low to the south disrupting this moisture feed until mid-week. So for temperatures, its a slow steady incline to seasonal normals. No major blobs of low level warm air, and even the GFS`s temporary depiction of an elevated mixed layer late Tuesday is not depicted as nearly as strong in the EC/Canadian. For precipitation, NBM is producing rather continuous POPs though the extended with few breaks. This is more a representation of a low confidence forecast as after Sunday, numerous GEFS members also show on and off low QPF values smattered across the course of the week. The NBM`s probabilities for 0.01" 24 hour QPF is roughly 30 percent just about every day, though with higher probabilities for higher values of QPF for the Wed/Thurs timeframe when the upper wave over the Pacific Northwest begins to migrate into the Rockies. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1234 PM CDT Sat Aug 10 2024 Terminals KABR,KATY,KPIR,KMBG Good VFR conditions are forecast for all terminals with light winds. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Dorn SHORT TERM...MMM LONG TERM...Connelly AVIATION...Dorn