Area Forecast Discussion
Issued by NWS North Platte, NE
Issued by NWS North Platte, NE
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053 FXUS63 KLBF 082018 AFDLBF Area Forecast Discussion National Weather Service North Platte NE 318 PM CDT Sat Jun 8 2024 .KEY MESSAGES... - Limited threat for strong to severe thunderstorms across southwest Nebraska this evening. Primary threat will be damaging wind gusts but isolated severe hail and heavy rain are also possible. - The next system to bring rain and thunderstorms arrives late Monday into early Tuesday as a cool front drops through the area. A few storms may be strong to briefly severe across the Panhandle. - Strengthening ridge towards the middle and late part of the week will support increasing temperatures. Signals continue to increase for hot days Wednesday and Thursday as highs climb into the middle to upper 90s across the southwest. && .SHORT TERM /THROUGH TONIGHT/... Issued at 317 PM CDT Sat Jun 8 2024 Scattered rain with a few embedded thunderstorms continue to track west to east across the Sandhills into central Nebraska. This activity will continue through late afternoon as a weak shortwave moves out of eastern Wyoming. Rainfall amounts have been light with the heavier cores being limited to rural areas of the Sandhills. A few locations may surpass a tenth of an inch but this should remain on a fairly isolated bases. Surface frontal boundary from Friday has shifted south into Kansas and with approaching high pressure from the north, surface flow has gradually shifted from northeasterly to easterly. This will set us up for another round of strong to potentially severe weather as upslope forcing should allow for scattered to widespread thunderstorms to develop off the Front Range and gradually shift east/southeast with time this afternoon and evening. With the ongoing activity largely north of Interstate 80, cloud cover has remained heavy and greatly limited diurnal warming. Further south to the I-80 corridor and points south, more clearing has occurred which has allowed afternoon temperatures to reach the middle 70s to near 80 degF by 18z (1pm). Mesoanalysis guidance depicts a sharp gradient in instability with the bulk of the greatest values (> 1500 j/kg MLCAPE) remaining south of the Nebraska/Kansas state line. Though a slight northward shift is expected with this later this afternoon as low level flow continues to veer to the east-southeast, the more favorable environment should remain south as MLCAPE values will likely only climb to around 1000-1250 j/kg versus 1500-2500 j/kg further south. Deep-layer shear is more than adequate for storm organization as 0-6km BWD will easily surpass 40 knots. Storms currently developing near the I-25 corridor of northern Colorado/southeastern Wyoming should quickly grow upscale as cold pools congeal and activity moves off the higher terrain. Storm track will generally follow the instability gradient which will likely steer it into far southwest Nebraska and northwest Kansas. The environment locally is supportive of at least an isolated severe threat...MLCAPE ~1000 j/kg, strong deep-layer shear, steep mid-level lapse rates of 7+ C/km, and PWAT values of 1.00"+ which nears the 99th percentile for early June. Given all this, believe a few reports of damaging wind and severe hail are probable. Am also concerned in a threat for briefly heavy rain though quick progression of storms should limit any flooding threat. Can`t rule out a few locations seeing up to 1.5" of rain before activity departs. They say the "trend is your friend" and it`s interesting to note that the HRRR signal for damaging wind gusts locally has decreased with concurrent runs of the model. This is noteworthy but likely not enough to suggest the severe threat is no more. For now, will continue to monitor upstream evolution of convection and adjust the forcast as necessary. Timing would favor after 4pm CDT and likely be closer to a 6-9pm CDT window for our far southwest. Activity should quickly exit with the bulk of short-term models depicting dry conditions in the local area by Midnight. Will maintain a low-end PoP through the overnight hours for our west and southwest zones, however, as modest low-level lift remains in an anomalously moist environment though most locations will likely remain dry. With encroaching high pressure, cooler temperatures are likely with upper 40s to low 50s outside the lingering stratus and middle 50s in. && .LONG TERM /SUNDAY THROUGH SATURDAY/... Issued at 317 PM CDT Sat Jun 8 2024 Sunday...Mid-level heights begin to rise as ridging noses into the central and southern Plains. Modest high pressure will drift through the middle Missouri River valley. With the local area on the western periphery of this feature, southerly flow will remain prevalent. This will continue to paint a narrow ribbon of greater moisture across the High Plains to include lingering low-level cloud cover. This will likely inhibit afternoon temperatures somewhat with forecast highs ranging from near 80 degF in the far east to low 70s in the west. Monday and Tuesday...broad ridging will center across the Plains by early Monday morning. Flow will flatten as a northern stream system translates east across southern Canada. This will drag a cool front south into the area. Ahead of this, the persistent southerly flow will maintain anomlaous moisture with PWATS exceeding 1" generally for areas west of Highway 83. These values will surpass the 90th percentile in NAEFS climatology. With fairly strong frontal forcing, scattered to widespread thunderstorms are likely to develop for the late afternoon and evening hours favoring the Sandhills north into South Dakota. NBM probabilities of exceeding 0.25" QPF for the period are roughly 50/50 for the far northwestern Sandhills and around 25% for exceeding 0.50". This is fairly modest considering deterministic solutions depict more widespread 0.50" or greater rainfall. Given discrepancies between ensemble soultions, however, will defer to later forecasts for more precise details. Latest SPC Day 3 outlook shows a Marginal Risk for the eastern Panhandle. For now believe this is adequate though both shear and instability are somewhat limited. Highs both Monday and Tuesday will climb into the upper 70s to lower 80s. Wednesday and beyond...signals for a couple days of more summer-like weather continue to strengthen in the local area. Broad ridging will again strengthen over the southern half of the CONUS. Meanwhile, a system will sit off the Baja of California as modest troughing slides east along the Gulf Coast. High pressure will strengthen across the southwest behind the departing trough which will again enhance southerly flow in the region as broad low pressure settles in the Great Basin. This will promote steady southerly flow advecting in richer low-level moisture. At the same time, ridging will continue to build north with h5 heights exceeding the 90th percentile. This will bring with it anomalous warmth in the mid- levels as h5 and h7 temperatures surpass the 90th percentile by late Wednesday, Thursday, and possibly lingering into Friday. All this to say it`ll be a couple of hot and humid days. NBM ensemble guidance shows fairly reasonable 25th to 75th percentile spread at only 6 and 9 degF respectively and the 50th percentile values pushing in the low to middle 90s. Combined with dew points climbing into the upper 50s to lower 60s, will be monitoring for heat indices climbing into the upper 90s. For now, no headlines are expected though with these first hot days of the season, messaging will be increased to keep people adequately aware. Precipitation chances look to linger through the period as well, particularly Friday into Saturday as NBM highlights 30-40% probabilities of seeing > 0.25" QPF. This is tied to an approaching shortwave interacting with the moist and hot airmass on the northern periphery of the upper ridge. Overall though, our days of high heat should be brief during the forecast period as ridging wanes by the following weekend. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1246 PM CDT Sat Jun 8 2024 Showers with some embedded thunderstorms will continue through the afternoon across much of north central Nebraska. These showers should diminish by early to mid-evening with overcast skies through the remainder of the TAF period. Stronger winds present this afternoon will gradually diminish by early evening as well with winds under 10 knots through Sunday morning. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...NMJ LONG TERM...NMJ AVIATION...Kulik