Area Forecast Discussion
Issued by NWS Hastings, NE
Issued by NWS Hastings, NE
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142 FXUS63 KGID 281744 AFDGID Area Forecast Discussion National Weather Service Hastings NE 1244 PM CDT Tue May 28 2024 .KEY MESSAGES... - Low end (20-30%), light precipitation chances mainly SW of the Tri-Cities next couple of days. Otherwise, quiet and mild. - Better chances (30-60%) arrive late Wednesday night, and especially Thursday into Thursday night (50-80%) with the arrival of a weak front. - Off and on thunderstorm chances (generally 20-50%) continue through the weekend owing to "dirty" zonal flow and perhaps a couple sfc boundaries in the area. - Overall severe weather threat days 4-7 remains uncertain, though probably not completely zero. Locally heavy rain could also be an issue, particularly Thursday-Friday. - Ensemble guidance is in general agreement for stronger upper ridging and warmer and drier weather arriving next week. && .DISCUSSION... Issued at 445 AM CDT Tue May 28 2024 Today - Wednesday: Not much change to the general forecast thoughts for the next couple of days - mainly dry and seasonably warm. Areas mainly SW of the Tri-Cities will be on the fringes of better mid level warm air advection and isentropic ascent over the next 24-36 hrs, but models remain consistent in keeping the highest chances/amounts from E CO into SW KS. Areas along and SW of a line from Arapahoe to Beloit have fairly persistent 20-30% chances of rain to account for this, with a mention of sprinkles to the north for a buffer. Temperatures look to remain very consistent (and pleasant) in the upper 70s to lower 80s. Winds will be lgt today, then incr out of the SE for Wednesday. Late Wednesday Night through Friday: Also not much change to the forecast thoughts from the past few days for Wednesday night. Still expect a swath of scattered thunderstorms to develop N-S along the Front Range/High Plains region Wednesday afternoon, then gradually shift E during the evening and overnight. Mid to upper flow is modest, so the E movement will be slow, but aided to some extent by broad and increasing low level jet. Some of this activity to make it to W zones after midnight, then further E towards Hwy 281 corridor around dawn Thu AM. Shear looks to be too weak, and primary instability axis remains W/SW of the area, so not expecting anything severe. What exactly happens the rest of the day and into Thursday night remains something of a mystery, but general consensus is that convection will redevelop at some point during the aftn/eve, either along lingering outflow boundaries, or along an advancing front from the NW in what otherwise looks to be an increasingly moist and uncapped environment. There will likely be at least a slight uptick in shear (locally enhanced by outflow boundaries) to around 30kt sfc-6km, but the primary plume of steep lapse rates remains over W/S KS, so instability will still be weak by late May standards. Severe weather threat is probably not completely zero, but looks to be more of a Marginal (level 1 of 5) type threat at this time, thus below the 15% minimum threshold for a day 4+ outlook. Of potential greater concern could be locally heavy rain given aforementioned weak flow and slow storm motion vectors. PWATs, while not tremendously high, will incr to around 1.5 sigma per latest EPS, and "tall/skinny" CAPE profiles will incr efficiency. It`s nearly impossible to pin down location of heaviest rainfall, but some of the most recent deterministic guidance gives localized 2-3+", which seems reasonable. Suspect this will be supported by hi-res CAMs once we get within their forecast range. Friday could see some lingering activity in the morning, but should generally trend drier through the day. Official forecast continues some 20-40% PoPs into Friday afternoon and night, but slowly rising heights and lack of coherent ascent mechanism makes me think this is overdone. Model guidance spread increases over the weekend with respect to handling of a few low amplitude shortwave troughs, but agree that general upper flow will be zonal or slightly SWrly. Am confident there will be off and on thunderstorms rolling through the region over the weekend, but there`s simply too much uncertainty and weak forcing to discuss possible specific outcomes. Severe risk could be greater than Thu-Fri given slightly higher mid level flow/shear and instability, but again, a lot will depend on features that are too unpredictable this far out. Temperatures should remain in the 70s or 80s, depending on cloud cover and rain coverage. Ensemble guidance is in better agreement that ridging will strengthen over the W 2/3rds of the CONUS by middle of next week, which should support and increasingly drier and hotter pattern locally. Core of highest temperatures anomalies should tend to focus W of the area, but latest EPS still gives better than 50/50 chances for highs breaching 90 deg for portions of the forecast area several days next week. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1235 PM CDT Tue May 28 2024 VFR Conditions expected through TAF period. Skies should remain clear this afternoon. FEW-SCT Mid level cloud coverage will move into the area this evening and continue overnight. MVFR conditions are possible at the end of the taf period, though confidence is not high in this scenario at this time. Have used SCT050 to indicate the potential. Northerly winds will decrease and become southeasterly overnight. Winds will increase after sunrise with sustained winds approaching 15KTs by the end of the TAF period. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ DISCUSSION...Thies AVIATION...Davis