Area Forecast Discussion
Issued by NWS Omaha/Valley, NE
Issued by NWS Omaha/Valley, NE
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
951 FXUS63 KOAX 040910 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 410 AM CDT Sat May 4 2024 .KEY MESSAGES... - Cooler today and tomorrow, with highs in the 60s and dry weather expected. - There is a chance of severe thunderstorms (15 to 30 percent chance) Monday afternoon and evening. - Additional chances for showers and storms possible through the end of the week, but no organized threat for severe storms. && .DISCUSSION... Issued at 409 AM CDT Sat May 4 2024 Today and Tomorrow: Water vapor imagery this morning shows a modest troughing over the far north-central CONUS, with a shortwave extending southward, pivoting eastward through the largely zonal mid/upper flow that the base of the trough sits on. A recent surface analysis shows high pressure moving into northwestern Nebraska behind a cold front that has helped spark early morning convection moving to the southeast of the forecast area. KOAX radar imagery this morning features the continued departure of the MCS/bow that has brought widespread gusts of 35 to 45 mph, and has struggled to keep up with its own outflow. A cooler and drier airmass is set to move in behind this convection and make for a rather comfortable weekend, with highs in the low-to- mid 60s expected today before only slightly warmer highs settle in for Sunday in the upper 60s. Winds this afternoon will slowly diminish from the gusty northwesterly flow this morning and begin turning southeasterly in anticipation of a stronger storm system to kick off the work week. Monday and Beyond: The main focus of the forecast period comes Monday, when a high- amplitude and negatively-tilting trough pivots eastward from the Rockies, shooting a cutoff low northeastward just to the north of the forecast area. Robust forcing for ascent will be in full effect by the afternoon hours along a dryline, with convective initiation expected to occur in central Nebraska. By the time it reaches eastern Nebraska and western Iowa, a narrow corridor of surface- based CAPE ranging from 1000-2000 J/kg will provide ample instability to accompany 0-6 km bulk shear values of 40 to 50 kts or more to allow for an increased probability of severe storms (up to 30 percent for parts of southeast Nebraska. All hazards will be possible thanks to the favorable curvature in the low-level hodograph and combo of strong forcing/sufficient instability/strong shear, though will take the form of a line/cluster of storms. This activity is expected to quickly pivot through the forecast area Monday afternoon and evening, leaving the area dry by midnight as storms lift north and east. For Tuesday through the rest of the work week, we`ll continue to be under the influence of the Monday system, which at this point will be occluded and cut off over the far northern High Plains. The main mid/upper level jet will be laid over the southeastern edge of the forecast area, keeping highs from rising much above the mid-to-low 70s with increasing chances for showers and storms returning for Thursday continuing into the weekend as the occluded system to the north finally gets slowly pulled away in the mid/upper flow. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1132 PM CDT Fri May 3 2024 The main concern of the TAF period continues to be the line of storms moving into eastern Nebraska over the next few hours. Those storms have already moved into the KOFK vicinity with lightning and rain, though ceilings and visibilities have yet to take a hit into MVFR or lower. Gusts as strong as 40 kts appear likely at KLNK when the line arrives around 0530 to 0600z, while areas north near KOMA see less intense storms with gusts as strong as 30 kts from 0645 to 0800z. Ceilings and visibilities are expected to take a hit behind the main line, with low-end MVFR ceilings and visibilities forecast through around or just after sunrise, with the area seeing clouds move out by late afternoon. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Petersen AVIATION...Petersen