Area Forecast Discussion
Issued by NWS Hastings, NE
Issued by NWS Hastings, NE
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846 FXUS63 KGID 281149 AFDGID Area Forecast Discussion National Weather Service Hastings NE 649 AM CDT Fri Jun 28 2024 .KEY MESSAGES... - Warmer today with isolated to scattered storms possible (20-50% chance, highest W of the Tri-Cities) once again this evening into the overnight. There is a Slight risk (level 2 of 5) that some of these storms could be severe. - Very pleasant temperatures behind a cold front for the weekend along with low-end (20-30%), mainly overnight, thunderstorm chances. - Warmer with continued storm chances next week, with highs in the 80s and 90s and mainly small chances for thunderstorms (20-40%) each day. Heat Index values could climb to 100-105F in spots both Monday and Tuesday afternoons. - Early look at Independence Day is for rather seasonable conditions - warm temperatures in the 80s-90s and 30-40% chances for showers/storms. && .DISCUSSION... Issued at 505 AM CDT Fri Jun 28 2024 After a few storms in the Hebron area early this morning, skies have turned clear to partly cloudy. Scattered elevated convection has shifted E/SE of the forecast area in response to a veering 45-50kt low level jet. Can`t completely rule out a few more elevated storms from Beloit to Hebron next few hrs, but this is only a 20% chance. A cold front will shift WNE to ESE across the area this morning and this could also be a source for some elevated, weak convection - as is currently noted over extreme NE Colorado. Forecast soundings suggest this activity is rooted around 10-12K ft with some dry air beneath it. So any rain amounts during the day today would likely remain very light. Winds will shift from S to NW with passage of the front, but despite this, full aftn sunshine should still allow for warm highs in the upper 80s to mid 90s for most spots. In fact, far S zones (Rooks to Mitchell Cos) could make a run into the upper 90s and heat indices 100-105F. Opted against heat headlines given largely marginal criteria and short-lived nature (today only). Worth noting that far S/SE areas could see elevated Wet Bulb Globe readings, though, given closer proximity to sfc front and likely lighter winds, along with pooling moisture. Expect two main areas for convective development late this aftn and eve, both of which will likely - at least initially - be outside of the local forecast area. One area will be along the sfc cold front, which by the time the cap is eroded (21-23Z), should be roughly along a line from OMA to SLN and only moving further E/SE away from the area. Another area will be over the High Plains (WY/CO/NE border area) within steep low level lapse rate environment and sufficiently moist/unstable post-frontal airmass, perhaps aided by slight upslope component. Capping will likely be an issue with time and eastward extent, but appears favorable post-frontal deep layer shear 35-45kt, consisting of long, straight hodographs, and moderate 1000-1500 J/kg of MUCAPE will be sufficient for at least some convective organization (splitting supercells and/or multicell clusters) and opportunity for activity to make it into W 1/3rd of CWA in the 00-03Z time frame. Large hail and damaging wind gusts look to be the primary threats. Activity will likely weaken after 03Z given lack of LLJ and incr inhibition/nocturnal cooling, but the rate of weakening will likely depend on storm scale processes. Given the recent model trends, wouldn`t be surprised to see the Slight risk (level 2 of 5) area trimmed a bit, esp. in our NE. Cooler, quite pleasant, conditions filter in behind another cold front tonight, setting the stage for an excellent late June weekend with highs in the 70s-80s. Refreshing Nrly breezes on Sat will help usher in seasonably low humidity which looks to stick around even on Sun, despite a turn in winds to the SE. Thunderstorm chances this weekend aren`t zero, but they`re not all that high, either, at only 20-40% Saturday night into Sunday. Slightly higher chances (30-50%) arrive Sun night. Continued return flow will lead to another round of hot, humid conditions for the start of the new work week as highs soar into the 90s to low 100s on Monday, and upper 80s to upper 90s on Tuesday. Off and on convection could throw a wrench into these numbers, but assuming some breaks late AM into the aftn, pooling low level moisture near a slow moving front could lead to elevated heat indices in the 100-105F for at least southern parts of the area each aftn. Elevated, warm air advection driven thunderstorms could present our next severe risk as early as early Mon AM (mainly large hail), but overall-highest chcs should come with arrival of aforementioned slow-moving front Mon aftn-eve. Portions of south central NE remains within 15% risk area on latest Day 4 SPC convective outlook. Of course, some refinements are likely as we get closer. Some models hint at the front hanging up W to E somewhere over the central Plains Tue into Wed - which if that pans out, could support a localized hydro threat given pooling moisture and PWATs around +2 standard deviations. Far too early to opine on specific areas at more risk than others. Rest of the forecast appears fairly seasonable in terms of highs in the 80s-90s and more off and on chances for storms - including on Independence Day. Will have to keep an eye on the specific timing of a potential upper disturbance and associated cold front hinted at in some of the model data - both deterministic and ensemble - as it pertains to holiday celebrations. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 645 AM CDT Fri Jun 28 2024 For KGRI/KEAR Airports: VFR through the period: Today: Sfc winds will veer through the day along and behind a weak cold front, from SSW this morning to NW this aftn, to NE this evening. Speeds will be mainly 8-12kt. Can`t rule out a few sprinkles this morning, but should be mainly mid to high level cloud cover. Confidence: High. Tonight: Main issue will be potential for iso-scat tstms to move in from the W around 01Z-04Z. Will probably need a VCTS with the next TAF cycle, but held off on this one given a possible track mostly S of the terminals. Winds may go lgt and variable late in the period. Confidence: Low to medium. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ DISCUSSION...Thies AVIATION...Thies