Area Forecast Discussion
Issued by NWS Hastings, NE
Issued by NWS Hastings, NE
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533 FXUS63 KGID 150641 AFDGID Area Forecast Discussion National Weather Service Hastings NE 141 AM CDT Sat Jun 15 2024 ...Aviation Update... .KEY MESSAGES... - A complex of thunderstorms is expected to move across the area late this evening and overnight. Storms will be strong to marginally severe, especially W/SW of the Tri-Cities, with damaging wind gusts the main threat. - Thunderstorm chances of some degree continue off and on nearly every day/night over the next week, which is not uncommon for this time of year. Beyond tonight, mid to late next week currently appears to be most favored time for more frequent and/or widespread rainfall. - Storms may be strong to severe from time to time, but any decent amount of forecast confidence in specifics will be limited to only 1-2 days out. Rain may be heavy next week. - Very warm LOW temps in the 70s most areas both Sun night and Mon night COULD at least approach record-warm values for June 17-18. Sun and Mon also look to be the warmest highs of the next week with widespread 90s and even some low 100s. && .UPDATE... Issued at 653 PM CDT Fri Jun 14 2024 Thunderstorm chances increase heading into this evening and tonight. A Severe Thunderstorm Watch has been issued for counties along and west of Highway 281 through 2AM Saturday. For additional details, please see the watch product. && .DISCUSSION... Issued at 445 PM CDT Fri Jun 14 2024 Temperatures have warmed well into the 80s across most of the area this afternoon, with even some low 90s noted over portions of north central KS. Easterly surface flow kept humidity levels seasonably low for most this AM, but a shift to SErly winds this afternoon has allowed for some moisture return - dew points into the mid to upper 60s, especially over the S/SW third of the forecast area. Outside of a stray, generally weak, shower or storm, think most areas will remain dry through around sunset. Latest forecast expectations are largely unchanged from the previous forecast in that thunderstorms that are currently developing along the Front Range of the Rockies will organize into an MCS over the High Plains this evening, then roll E/NE into our W/SW zones around 9-10PM. Strong to severe storms will be possible with this activity, particularly W of Hwy 281 where instability will be strongest, with damaging wind gusts 60-65 MPH the main threat given expected linear storm mode. Perhaps some marginally severe hail, too, in the strongest cores. Instability has trended higher in the models for more of our area overnight, so storms may not dissipate quite as quickly, though I do think the severe risk will still dissipate with time and eastward extent given lack of strong LLJ convergence and modest deep layer shear only 25-30kt. This should be good news for most as latest HREF produces a fairly broad swath of 0.25-0.75" of rain - which will be much appreciated given the upcoming hot/windy conditions Sun-Mon. Of course, some locally heavier amounts are likely, but don`t think flooding will be an issue given the progressive nature of the broader complex. Finally, want to mention that 0-3km shear values 30-35kt, oriented favorably (perpendicular) to the expected line, along with sufficient 0-3km CAPE, could present a non-zero risk for a couple/few QLCS tornadoes overnight, as well. Saturday: Most, if not all, of the rain should be out of the area by around sunrise, with mainly dry conditions expected rest of the morning and most of the afternoon. Anytime after 4-5pm, isolated to widely scattered thunderstorms may develop over mainly E 1/3 of the CWA within the departing mid level trough axis and along a sfc moisture gradient. Upper height changes will be neutral or slightly rising and sfc convergence is weak, so coverage should be pretty limited. Models that do generate convection have generally trended most E/NE, now mostly along and E of Hwy 81. This is depicted well in the SPC Day 2 outlook, though the western extent of the Marginal may be generous. Otherwise, expect a typical warm and somewhat muggy mid-June day with highs in the mid 80s to low 90s. If any storms develop they will shift E by late evening, leaving dry wx for rest of the night. Sunday - Monday: Main story for these days will be increasing heat - with afternoon high temps in the 90s to even low 100s each day. There will be some humidity present, so heat indices may approach 105F in spots, particularly near and S of the state line. However, moisture doesn`t look to be too oppressive and there will be at least breezy conditions each day. In fact, Monday could be outright windy and feel like a furnace with winds gusting 30-40 MPH. Worth noting, though, that the experimental Heat Risk index will be in the RED (level 3 on scale of 0 to 4) for areas around the Tri-Cities S and E both days - likely owing to the warm overnight lows and it being pre-July/August. In fact, overnight lows in the 70s most areas both Sun night and Mon night COULD at least approach record-warm values for June 17-18. Convective potential is highly uncertain, though probably not zero. Mid to upper height rises and H7 temps 12-15C will be fairly hostile to convective development in a broad sense...but locally intense heating/low level mixing/lapse rates and convergence along a gradually southward sinking boundary could both be potential triggers for iso storms during the late aftn/eve. This type of setup makes storm development at all HIGHLY conditional, but IF something develops, then strong instability and modest shear could support hail and gusty winds. Some model guidance suggests scattered storms developing SW of the area where those two triggers overlap the most, then some sort of MCS moving NE along the boundary Sun eve/night - but confidence in this specific scenario is low. Rest of the forecast: Generally speaking, the upper level pattern looks to become one that favors frequent chances for showers/storms - featuring broad/persistent troughing over the Rockies and strong upper ridging over the NE CONUS. This would keep our area in SW upper flow amidst increasingly cool mid level temps and less capping. Also, there is multi-ensemble agreement that a persistent fetch of moisture-rich Gulf of Mexico air will arc it`s way into the Plains and upper Midwest in a "ring of fire" type fashion, with multiple days of PWAT values 125-150% of normal. Combine this with weaker capping, "dirty"/active SW upper flow, and perhaps a quasi-stationary surface front and there could be a setup for heavy rain. Obviously, specifics on day-to-day details is still very low, but would say that I`m becoming increasingly confidence in this type of general pattern setting up for mid to late next week given the model-to-model and run-to-run consistency. Unsure of severe weather potential, but probabilities already north of 50% for at least 2" of rain on a global ensemble argues that heavy rain will be a threat worth monitoring over the coming days, though an even stronger signal lies over the Upper MS Valley region. Temperatures, in general, should cool off some from the HOT Sun/Mon, but specifics will likely be highly tied to clouds/rain and any stalled front(s). && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 140 AM CDT Sat Jun 15 2024 For KGRI/KEAR Airports: - General overview: Very high confidence that the vast majority of the period features VFR ceiling/visibility and rain/thunderstorm-free weather, with the overall-main feature of the period being moderately-breezy south winds especially during the day Saturday. That being said, these first 2-3 hours right away this morning will feature lingering light rain and possibly a few weak thunderstorms, and there is a roughly 4-hour window of opportunity for possible MVFR/IFR ceiling in the wake of the departing rain. - Ceiling/visibility/rain and thunderstorm details: Right out of the gate early this morning, both KGRI/KEAR are down to no more than 2-3 more hours of steady light rain (visibility mainly VFR) and perhaps a rogue/weak thunderstorm, but any threat of 40+KT gusts or possible hail has clearly passed for the night. In the wake of departing rain, have assigned a TEMPO BKN015 group to the 10-14Z time frame to handle possible low ceiling development, as still hinted at by various models/guidance. IF this low ceiling does form, MVFR is most probable, but brief IFR probably cannot be ruled out. Once any possible low ceiling scatters out, the remainder of the period is high-confidence VFR, although at least a lower-VFR scattered cumulus field is possible during the day. There is also the slightest possibility for a late afternoon thunderstorm, but with most models suggesting this activity would focus at least 50-75 miles to the east-southeast, have left out of TAFs. - Winds: Once short-term convective influences ease up over these next few hours, the general expectation is for early morning breezes to become established out of the southeast at generally 10-15KT. Then, during the daylight hours and particularly between 17-23Z, moderately breezy south winds will kick in...mainly sustained 15-20KT/gusts 25-30KT. Following a brief lull in speeds late afternoon/early evening, another modest increase is likely very late in the period (mainly after 03Z), with gust potential back up around 20KT. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ UPDATE...Wekesser DISCUSSION...Thies AVIATION...Pfannkuch