Area Forecast Discussion
Issued by NWS Hastings, NE
Issued by NWS Hastings, NE
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539 FXUS63 KGID 151156 AFDGID Area Forecast Discussion National Weather Service Hastings NE 656 AM CDT Sat Jun 15 2024 ...Aviation Update... .KEY MESSAGES... - Mainly between 5 PM-Midnight this afternoon-evening, primarily the southeast half of our coverage area (CWA) stands a small/somewhat conditional threat of popping off a few strong to perhaps severe thunderstorms. This threat would likely be fairly localized in our CWA, with better chances for potential severe focusing slightly to our east (eastern NE into western IA). - Although mainly northern parts of our CWA have small/"iffy" chances for storms Sunday evening into Monday, the MAIN STORY Sunday-Monday turns to heat, as both days look to feature highs well into the 90s, with mainly Sunday also featuring heat index readings as high as 100-105 especially in southern/eastern areas (flirting with Advisory criteria). - In addition to being hot, Monday will be rather windy by mid- June standards, with southerly gusts up around 40 MPH likely. - Record-warm LOW TEMPERATURES possible for Monday (June 17) at Grand Island/Hastings airports (see separate CLIMATE section below). - Sunday evening onward, each and every day/night forecast period features at least small rain/thunderstorm chances, with the overall-most widespread activity currently anticipated Tues-Wed when the next weak cold front sags southward into our area (which also could give us at least one somewhat-cool day for Wednesday). && .DISCUSSION... Issued at 545 AM CDT Sat Jun 15 2024 -- PRIMARY CHANGES TO THIS 7-DAY FORECAST VERSUS THE PREVIOUS ONE (issued Fri afternoon): - Honestly, nothing particularly noteworthy, as overall the basic expectations/highlights remain intact (as covered in KEY MESSAGES above). That being said, it is worth nothing that high temps for Wed continue to trend downward (down a solid 5-10 degrees versus 2 days ago), as confidence grows that this will be the coolest day of the next week. -- 7-DAY FORECAST OVERVIEW/HIGHLIGHTS: - CURRENT/RECENT WEATHER SCENE AS OF 5 AM: Although there is always a chance that daylight could bring a "surprise" report or two, our initial overall impression of our later evening-overnight thunderstorm complex (MCS) was that it turned out about as ideal as could be hoped: 1) it was an overall "dud" in terms of truly severe weather (the vast majority of known wind gusts were only 45-55 MPH tops) and there was no sizable hail...tough to pin down a specific reason why it was a weaker event, but lack of strong deep-layer shear probably contributed. 2) Although there were limited drier/wetter exceptions, a good majority of our CWA picked up at least 0.50-1.50" of rain overnight...much needed from the perspective that the preceding 6 days had been very dry and that we have a few hot/windy days ahead of us. As of this writing, the main linear complex has pushed well off to our east into the NE/KS/MO/IA border region, leaving our CWA mainly dry, but interspersed with spotty/isolated showers and perhaps an occasional weak thunderstorm. In the big picture of the mid-upper levels, water vapor imagery and short term model data confirm that a shortwave trough is centered over western NE/KS early this morning (slowly trudging east). At the surface, breezes in most areas are mainly out of the southeast at 5-15 MPH, having "recovered" in the wake of convective outflow. Overnight temps are on track to bottom out between 64-69 most areas. --TODAY INTO THIS EVENING (through midnight): In the big picture aloft, the aforementioned shortwave trough will continue tracking due eastward and directly overhead, with its axis crossing over our CWA this afternoon-early evening before it reaches a line from IA to eastern KS by midnight. Meanwhile, at the surface, deepening low pressure mainly over the Dakotas will allow our winds to become breezy out of the south and southwest...effectively allowing a warm front to surge off to our north and east this afternoon. Prior to this warm front making its surge, the day will likely start with considerable cloud cover (including low stratus many areas). However, this should steadily burn off/vacate from south-to- north with time, aided by southerly winds sustained at least 15-20 MPH/gusts at least 25-30 MPH this afternoon. High temps will be a bit tricky depending on how quickly skies become at least partly cloudy/mostly sunny, but most areas should be near- to-slightly warmer than yesterday, with highs aimed a few degrees either side of 90 most places. The million dollar question is: will we see at least spotty strong to severe thunderstorm development later this afternoon- evening? Backing up this morning-early afternoon, expect MOST places to be dry with only spotty showers/sprinkles mixed with a FEW weaker thunderstorms here or there. By mid-late afternoon, the aforementioned upper wave will be passing overhead, BUT the main lift out ahead of it, along with the primary surface warm front convergence, should be at least slightly off to our east by then, focusing a better chance for severe storms into far eastern NE/western IA. That being said, there is at least a small chance for a few strong to severe storms to develop mainly within our KS and southeastern Nebraska counties (south and east of the Tri Cities), which could go severe in a moderately- unstable environment featuring mixed-layer CAPE up around 2000 J/kg. However, deep-layer shear appears seasonably-weak through this time frame (mainly only 20-30KT), which in theory should limit the threat. So in summary, we have a conditional threat for a few severe storms mainly between 5 PM-midnight, and mainly within SPC`s current Slight Risk area focused within our eastern zones. - LATE EVENING-OVERNIGHT: Once any possible storms vacate our far southeast zones this evening (and assuming that no additional weak activity drifting eastward off the High Plains is able to infiltrate our CWA before it dies off), we are expecting a dry overnight with steady southerly breezes holding low temps from dropping any lower than 66-72 most areas. - SUNDAY-SUNDAY NIGHT: A return to legitimate HEAT is the number one story here, as at least for now our daytime forecast remains void of any thunderstorm chances as lack of forcing and warmer air aloft should effectively cap us off. Although southerly breezes will average 10-20 MPH in most areas (except lighter in our north- northwest near a weak/stalling front), providing some relief from the heat, we are looking at widespread highs in the mid- upper 90s most areas, which combined with dewpoints in the 60s (perhaps near 70 mainly northeast) will drive heat index readings well into the 98-103 range most areas. This is technically just short of our 105+ Advisory criteria, but obviously plenty close. Sunday evening-overnight, it will remain very warm, with overnight lows mainly up in the 70-75 range providing only limited relief. Rain/thunderstorm-wise, the vast majority of regional thunderstorm activity should remain at least slightly off to our west-through-north Sunday evening, overnight, but our forecast does carry some small PoPs especially north of I-80, just in case. - MONDAY-MONDAY NIGHT: Like the previous 24 hours, the vast majority of rain/storm potential should focus to our north, but mainly our northern zones do carry some small PoPs for now. Overall though, we are looking at another hot and actually rather windy day by mid-June standards. In fact, much of the day should feature sustained winds at least 25-30 MPH, gusts to around (possibly slightly more than ) 40 MPH. While these winds will provide a bit of relief from the heat and likely allow dewpoints to mix down a bit and not be quite as high as Sunday, actual high temps should still reach well into the 90s most places. - TUESDAY-WEDNESDAY NIGHT: An upper trough passing well to our north will drive a decent cold front southward into our region, sparking what will likely be our most widespread rainfall/thunderstorm chances of the week. Although details are still plenty uncertain, at least limited severe storms and localized heavy rainfall are quite possible. This front should keep Tuesday at least slightly cooler than Monday, but the REAL cooler air takes center stage Wednesday, which currently has highs ranging near-70 far northwest to near-80 far southeast. - THURSDAY-FRIDAY: Obviously plenty of uncertainty out at this range, but early model suggestions call for the front to start lifting back north, allowing temps to climb back into the 80s area-wide Thurs and mid 80s to low 90s Friday. Various, mainly low/uncertain thunderstorm chances also continue. && .AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 654 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 (and a round of low level wind shear late tonight). That being said, mainly these first 2-3 hours right away this morning will feature MVFR/IFR ceiling and perhaps a few more showers/weak thunderstorms. - Ceiling/visibility/rain and thunderstorm details: Right out of the gate early this morning, both KGRI/KEAR could see around 2-3 hours of continued MVFR/IFR ceiling, along with a few passing showers/weak thunderstorms (with coverage spotty have assigned a generic "vicinity thunderstorm"/VCTS for this). By around 15Z, ceiling should scatter out/and/or lift to VFR territory, with nothing more than a "fair weather" low-VFR cumulus field expected this afternoon. Any late afternoon- evening thunderstorm activity is expected to focus mainly 75+ miles to the east-southeast, so have left out of TAFs. - Winds: -Surface winds: While winds are starting off southeasterly right away this morning, they will soon turn more southerly today into tonight as a warm front lifts north, with the majority of the period featuring sustained speeds 15-20KT/gusts 20-30KT (overall- strongest this afternoon). - Low level wind shear (LLWS): As a strong southwesterly low level jet kicks in late tonight, a period of moderately-strong low level wind shear will commence around 05Z. More specifically, winds within roughly the lowest 1,500 ft. AGL will accelerate to around 45KT out of the south- southwest, setting up a solid 30-35KT of shear magnitude between the surface and this level. && .CLIMATE... Issued at 545 AM CDT Sat Jun 15 2024 -- Regarding possible RECORD WARM LOW TEMPS on Monday (June 17th): Both Sunday night-Monday morning and Monday night-Tues morning are expected to remain very warm, with most of our CWA not dropping below the low-mid 70s. As a result, calendar day (midnight-to-midnight) records for warmest low temperature could be threatened at Grand Island/Hastings airports (the 2 sites for which we issue formal Record Event Reports/RERs). Any such records are most likely to be threatened on Monday the 17th, because a cold front arriving Tuesday the 18th is currently expected to drop temps safely below record territory by midnight that night. - GRAND ISLAND Record Warm Low Latest Forecast Monday June 17th 74 (1906) 73 - HASTINGS Record Warm Low Latest Forecast Monday June 17th 72 (2020/2014/1946) 73 NOTE/REMINDER: in order for a new record warm low/minimum temperature to become official it has to "survive" the entire 24-hour calendar day (in other words, it is not always based solely on the early-AM low temp). && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ DISCUSSION...Pfannkuch AVIATION...Pfannkuch CLIMATE...Pfannkuch