![National Oceanic and Atmospheric Administration](/build/images/header/noaa.d87e0251.png)
![National Weather Service](/build/images/header/nws.4e6585d8.png)
![United States Department of Commerce](/build/images/header/doc.b38ba91a.png)
Area Forecast Discussion
Issued by NWS North Platte, NE
Issued by NWS North Platte, 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
43
371 FXUS63 KLBF 101743 AFDLBF Area Forecast Discussion National Weather Service North Platte NE 1243 PM CDT Sat Aug 10 2024 .KEY MESSAGES... - Cloudy and cooler again for Saturday with afternoon highs 5 to 15 degrees below normal. - Multiple rounds of rain and thunderstorms are expected over the next 48 hours, primarily late tonight into early Sunday morning and again Sunday afternoon and evening. Strong to severe thunderstorms are possible with each round of thunderstorms. - Temperatures look to return to climatological values early next week with continued southerly flow supporting daily rain and thunderstorm chances. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 340 AM CDT Sat Aug 10 2024 Morning satellite analysis shows broad troughing across the Great Lakes region as low-amplitude ridging settles across the Great Basin. A fairly notable plume of sub-tropical moisture was crossing the central and southern Rockies where low-level fog and scattered rain and thunderstorms are noted as of 0730z. Surface high pressure situated across northwest Kansas will continue to settle east and lead to increasing southerly flow later in the day. Saturday...Low-stratus remains prevalent across the area as surface high pressure maintains local influence. Areas of fog have been noted across far northeast Colorado but this activity should remain south and west of the local area. As the central high pressure continues to drift east, southerly flow will overspread the area. Modest WAA will support continued cloud cover for the bulk of the daytime which should help keep temperatures on the cooler side. Forecast soundings indicate stratus layer will be shallow, around 1 to perhaps 2km thick. With modest if any lift in the layer and a fairly strong inversion located immediately above this, believe precipitation prospects for the daytime are fairly low. This idea is supported by most NWP guidance including HREF and deterministic NAM/GFS/RAP solutions. Capped inherited PoPs at 16% with timing closely resembling SREF output. Again, expectation is for most if not all locations to remain dry. Regarding temperatures, confidence remains fairly low in magnitude of warming today. Latest statistical guidance ranges from 70 degF (MET), to 76 degF (ECS), up to 80 degF (MAV) for LBF. NBM percentile values reflect this split with 25th and 75th percentile values exhibiting a 9 degF split. Though skies will likely limit insolation greatly today, the modest WAA with the increasing southerly flow suggests at least a limited warm up across the area. Went ahead and utilized a CONSRaw/NBM 50th blend which closely lines up with latest short-term guidance. This paints low 70s near and just north of the I-80 corridor to near 80 along the Nebraska/South Dakota border and far southwest Nebraska. Attention quickly turns to the threat of convection as early as late afternoon in our western zones but more likely arriving in the mid to late evening hours from the west. Southeasterly surface flow interacting with the Laramie Range will lead to afternoon thunderstorm development. While strong mid-level flow will support adequate deep- layer shear for storm organization, limited low-level moisture will hamper instability magnitude as MUCAPE values appear limited to around 1000 j/kg in our far western zones. The greatest overlap of low-level moisture tongue and mid-level lapse rates will form a northwest to southeast instability axis stretching from near Chugwater, WY down through Yuma, CO. This will likely reinforce a northwest to southeast storm motion which should steer most activity around the area. Far southwest Nebraska will still be in the area of concern for strong to briefly severe thunderstorms and it is here where the Storm Prediction Center maintains a Marginal Risk (level 1 of 5). The main concern would be damaging wind gusts, however, storms are likely to lose intensity quickly as they outrun the greatest instability. While anomalous moisture will remain in place, quick storm motion and weakening convective elements should preclude a greater heavy rain threat. Even so, a few locations may still manage to see over a quarter inch of rainfall. Sunday...surface high pressure continues to slowly track east, further away from the local area. This will support south to southeasterly flow locally. Broad easterly flow across Kansas will inhibit WAA and moisture advection, at least initially, across the local area. Later in the day, low-level moisture advection will increase with model guidance suggesting surface dew points climbing into the upper 50s to low 60s. Temperatures at h85 will remain fairly stagnant from Saturday, so little in the way of a warm up is expected. Afternoon highs, again under partly to mostly cloudy skies, will likely remain in the 70s and 80s. A warm front will sharpen across our northwest zones late in the day as a shortwave approaches from the west. With continued strong mid-level flow, deep layer shear will once again be favorable for storm organization and the threat for strong to severe thunderstorms. The greatest overlap of shear and instability will favor invof this warm front and immediately north where more easterly surface flow will elongate hodographs. Even so, forecast shear profiles show limited low-level curvature outside a 20 mile buffer from the main surface boundary and limited low-level lapse rates which inhibits both SBCAPE and 3CAPE values. Above 1km, hodographs are fairly long and straight which generally support splitting supercells and a greater threat for large hail and damaging winds as opposed to tornadoes. Even so, non-negligible overlap of surface vorticity along the boundary in a localized pool of richer moisture suggest the threat for a brief tornado cannot be ruled out. The latest SPC Day 2 outlook highlights most of western Nebraska in a Marginal Risk (level 1 of 5) for Sunday. Generally have no qualms with this, however, latest hi-res guidance have indicated more scattered coverage with fairly high concentration of moderate updraft helicity tracks. Should this idea continue, wouldn`t be surprised to see a necessary upgrade to the Severe Weather Outlook. As mentioned before, low-level moisture will increase in the warm sector. Though instability response to this appears fairly limited, increasing moisture quality suggests a greater threat for locally heavy rain. HREF probability-matched mean values for the 24 hour period ending Sunday evening suggests rainfall amounts exceeding a half inch for much of north central Nebraska and even some locations approaching 2.0" total rain for the day. This generally matches individual NAM Nest/RAP/HRRR output with multiple swaths of 1-2". This partly explains the latest Day 2 Excessive Rainfall Outlook which highlights these areas in a Marginal Risk. While the threat for Flash Flooding appears limited, locally heavy rain could introduce low-land flooding so this threat will need monitored with subsequent forecasts. Precipitation chances should diminish late Sunday into early Monday as the main shortwave trough clears the area and heights begin to build immediately behind the mid-level disturbance. && .LONG TERM /MONDAY THROUGH FRIDAY/... Issued at 340 AM CDT Sat Aug 10 2024 Overall, a fairly active pattern will remain in place for the first half of next week. Upstream ridging will amplify slightly, with the ridge axis approaching the area by early Monday. This ridge axis looks to settle into the area by late Monday. This support warming temperatures with highs returning to the upper 70s to low 80s for Monday and climbing further into the middle 80s to lower 90s by Wednesday and Thursday. Even with increasing mid-level heights, rain and thunderstorm chances will persist as southeasterly surface flow drives rain and thunderstorms off the mountains to the west with a track moving through western Nebraska. Ensemble guidance varies on more precise timing next week, but near daily chances will exist. Utilizing the NBM 90th percentile values, the main windows appear to be late Monday into early Tuesday and again to a lesser degree late Tuesday into early Wednesday. This output closely aligns with the latest EPS solution with locally heavy rainfall amounts suggested by this modest suite. Temperatures will continue to increase with NBM 25th and 75th percentile values settling low 80s to near 90 degF respectively each day Tuesday through the following weekend. This suggests limited concerns for excessive heat but a quick return to more seasonable values in the extended periods. Latest Climate Prediction Center outlooks for the 6-10 and 8-14 day periods both favor above normal temperatures but a flip from above normal precipitation to below normal precipitation. This looks to coincide with a return to amplified ridging along the spine of the Rockies around the middle of the month. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1242 PM CDT Sat Aug 10 2024 Stratus continues to be present across western and north central Nebraska. Model guidance is struggling to catch on to the redevelopment of lower ceilings, which is being observed on satellite. Tended to the more aggressive solutions on ceilings, as MVFR to VFR conditions persist this afternoon and evening. Overnight ceilings should remain VFR, with a drop to IFR and LIFR ceilings along and south of Highway 2 tomorrow morning. As thunderstorms track in from the west this evening and overnight, they are expected to weaken and bring periods of showers around both terminals. Though the winds are expected to remain fairly light, decaying thunderstorms and showers may introduce some briefly erratic winds. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...NMJ LONG TERM...NMJ AVIATION...Richie