Area Forecast Discussion
Issued by NWS Omaha/Valley, NE
Issued by NWS Omaha/Valley, NE
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950 FXUS63 KOAX 180735 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 235 AM CDT Sat May 18 2024 .KEY MESSAGES... - A weak cold front moving through this morning will bring slightly cooler temperatures to the region. - Several rounds of strong to severe thunderstorms will be possible Sunday afternoon through Tuesday afternoon. All modes of severe weather will be possible including flash flooding. - There will be additional chances for storms (40%) Thursday into next weekend. && .DISCUSSION... Issued at 235 AM CDT Sat May 18 2024 Mostly clear skies across the area early this morning, but we do have a cold front approaching the area from the northwest. On satellite we see the cold front stretching from the surface low over eastern South Dakota down to southwestern Nebraska. This front will start to move into northeast Nebraska around 7 AM this morning and continue southeastward across our area through the morning bringing in cooler air for the afternoon. High temperatures today will mostly be in the upper 70s to low 80s, apart from far southeast Nebraska and southwest Iowa, areas which may see high temperatures reached in the mid-to-upper 80s before the cold front arrives. Sunday starts a pattern shift to much more active weather through early next week. We see a series of shortwaves bring chances for showers and storms, as well as the potential for flash flooding and severe weather. The trough train I guess actually started with the trough tonight, but with dry air in place, we don`t see any precipitation with this system. The next shortwave arrives late tonight which kicks the surface High off to the east. We see the development of a strong surface low over western Kansas which sets up a strong low-level jet across the Central Plains, advecting moisture into our region from the Gulf of Mexico. Models differ on the placement of the warm front from the surface low across western Kansas, with the GFS placing it farther south in northern Kansas while the NAM brings it north into southeastern Nebraska. Expect shower and storm activity to develop overnight late Saturday night north of the warm front through the morning hours Sunday morning associated with the passage of the shortwave. The Sunday afternoon/evening activity has become more conditional due to the morning storm activity. SPC has honed in on this by downgrading the severe potential across our area to Marginal. The concern is that lingering showers and cloud cover will struggle to clear in time to allow for the environment to recharge for a stronger second round during the evening as suggested in the models just yesterday. The NAM still shows this potential across southeast Nebraska south of the warm front, but the GFS with the warm front well south of our area keeps the severe weather potential to a narrow window right around 00Z and fairly low. Will continue to message that there is a conditional threat if we see clouds clear early enough for the environment to recover with a more northerly track of the surface low on Sunday. The next shortwave will bring another round of storms through Monday night into early Tuesday. We could potentially see another chance for severe weather again dependent on the track of the surface low, with a more northerly track bringing a greater potential for severe storms, while a more southerly track brings a greater potential for heavy rainfall with isolated large hail. Tuesday afternoon another trough will move through bringing more showers and storms and again, potential for a few strong to severe storms. This time, the greater potential will be for far southeast Nebraska and southwest Iowa, though models have been trending slower which would could potentially add in far eastern Nebraska to the potential for severe storms if this trend continues. Still the better chance for severe storms on Tuesday will probably be east of our area as storms may develop in our southwest Iowa counties but quickly move off to the east. Good news is it does look like at least right now we see a break in storm chances on Wednesday. Haven`t completely removed PoPs as ensembles have kept low PoPs in through the day. Right now though it does look like Wednesday should be mostly dry with highs in the upper 60s to low 70s. Toward the end of the week we see another system that will bring more storms on Thursday or Friday. We do see temperatures climb back up into the upper 70s toward the weekend though chances for showers and storms linger. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 946 PM CDT Fri May 17 2024 VFR conditions are expected through this TAF period with a low probability of a few showers and thunderstorms (<20%) overnight in association with a veered nocturnal low-level jet. In addition, low-level wind shear is expected through the overnight hours. A cold front will move south through the sites on Saturday turning winds to the northwest with gusts up to 20-25 kts through Saturday afternoon. Gusts should dissipate toward sunset Saturday. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...McCoy AVIATION...Kern