FXUS63 KGID 021211 AFDGID Area Forecast Discussion National Weather Service Hastings NE 711 AM CDT Fri May 2 2025 ...Aviation Update... .KEY MESSAGES... - Although any location that picks up more than 0.10-0.15" should consider itself lucky, our entire forecast area (CWA) stands at least some chance for passing showers/non-severe thunderstorms today through around sunset today. - Although frost is not a "sure thing" everywhere due to some modest uncertainty in our temperature forecast, a Frost Advisory has nonetheless been hoisted for our entire CWA for early Saturday morning (the only frost potential in the entire 7-day forecast). - From sunset this evening through at least mid-afternoon Monday, our forecast is all-but-guaranteed DRY...paving the way for what will be an overall-spectacular weekend by early- May standards. - Mainly Monday evening-Thursday brings a return of various intermittent rain/thunderstorm chances. However, the severe weather risk currently appears seasonably-low. - Temperature-wise: overall these next 7-days very seasonable/typical for early-May, with highs on MOST days 60s-70s and lows on MOST nights 40s. && .DISCUSSION... Issued at 550 AM CDT Fri May 2 2025 -- PRIMARY 7-DAY FORECAST BIG PICTURE THOUGHTS, CHANGES, UNCERTAINTIES: - Up front note: Given that this was this forecaster's "first go-round"/deep-dive through these next 7 days, honestly don't have a great "feel"/history regarding how things have been trending. That being said, a quick side-by-side comparison between this latest "forecast package" and our previous one (issued Thurs afternoon) reveals no changes of any real significance. - From an outdoor activity/comfort standpoint, this weekend's weather (Sat-Sun) appears to be about as good as it gets for early-May (plentiful sun, comfortable temps, not overly- windy...although a little breezy Sunday). - Probably one of the biggest "pleasant surprises" to this forecaster coming off a few days off is the apparent LACK of severe weather potential with any of next week's intermittent thunderstorm chances. Obviously plenty of time for a "sneaky" strong to marginally-severe setup to sneak into the fray, but by May standards nothing looks all that concerning at this time (and accordingly SPC has nothing outlooked for severe even remotely close to our area on the latest Day 4-8 Severe Outlook). - Obviously the one thing we DO NEED (especially our central counties/ including the Tri Cities/ which have missed out more than other parts of our CWA during the last week) is RAIN. Other than today's limited potential (at least amount-wise), unfortunately the aforementioned Mon-Thurs chances don't currently appear promising for truly WIDESPREAD/SIGNIFICANT amounts either. In fact, very preliminarily, most of our CWA is only expected to realize cumulative Mon-Thurs totals between 0.20-0.80...not enough to really "move the needle" on the widespread Moderate (D1) to localized Severe (D2) Drought still blanketing the majority of our CWA. -- 7-DAY FORECAST CHRONOLOGICAL RUNDOWN: - CURRENT/RECENT WEATHER SCENE AS OF 5 AM: Rainfall-wise: although it wasn't much in most places (most places picked up no more than 0.05-0.15", nearly our entire CWA saw at least a touch of rain through the evening-overnight hours, mainly in the form of a fairly narrow, northeast- southwest oriented band of light showers that pushed through and has now all-but-departed our far southeast fringes. Meanwhile, a new batch of spottier light showers has started to brush down from the north into our far northern CWA. In between these "pushes" of precipitation, much of especially the southwestern 2/3rds of our CWA has temporarily seen clearing skies. In the mid-upper levels, water vapor satellite and short term model data reveal a highly-amplified pattern over the united States, with a large-scale ridge/high prevailing over roughly the west half of the nation while a large-scale trough dominates roughly the eastern half. On the smaller scale, our rain chances these next 16 hours or so will be driven by a shortwave trough tracking directly overhead as it travels along a south-southeast trajectory from SD/NE toward MO/AR/eastern OK. At the surface, a high pressure axis centered from the Northern Rockies into the western Dakotas is the main driver of our ongoing northwesterly breezes (most places currently sustained 5-15 MPH). Temperature-wise, most of our CWA appears on track to bottom out in the 40-48 range. -- TODAY-EARLY THIS EVENING (through around sunset): While most places will be dry MOST of the time, these next 16 hours or so will bring at least some chances for at least isolated-to-scattered rain showers and a few non-severe thunderstorms to our ENTIRE CWA, but with the overall-highest coverage of this activity likely favoring our eastern 2/3rds. This activity, which will gradually build southward into/across our CWA as the day wears on, will be driven by a combination of forcing from the aforementioned shortwave trough, enhanced from late morning through late afternoon from modest low-level heating and steepening of low-level lapse rates. Severe storms appear pretty unlikely (only "general thunder" from SPC), but we probably cannot rule out a few instances of small hail and/or wind gusts into the 40-50 MPH range given that the latest RAP13 calls for mixed-layer CAPE (instability) perhaps as high as 200-500 J/kg. One of the main changes from previous forecast is that slight (20%) chances for the last of this lingering activity have been extended into the first part of the evening "forecast block" (7-10 PM), mainly for several counties along/east of Hwy 281, which are most likely to see the last of this activity before it dies off completely with the setting sun and departure of the upper wave. In other departments today, even aside from any enhanced gusts from developing convection, it will be somewhat breezy with north-to-northwest winds commonly sustained 10-20 MPH/gusts 15-25 MPH). The high temperature forecast carries a bit of uncertainty depending on how widespread showers/storms become, but made very little change with most places aimed right around 60, any mid-60s most favored far south-southwest. - LATE THIS EVENING-OVERNIGHT (after 10 PM): As the upper shortwave departs southeastward and a high pressure axis settles in at the surface, the stage will be set for what will almost certainly be the coldest night of the next week, with the "million dollar question" being just how cold it gets and the resultant magnitude of a frost threat? Overall, it should be a fairly ideal radiational cooling night, with light winds decreasing to 5 MPH or less and what should be clear/mostly clear skies (assuming no pesky patches of low stratus materialize). Given that this overall setup appears to more strongly favor a "colder than expected" versus "warmer than expected" temperature outcome, if anything nudged down low temps very slightly from previous (but overall little change). The net result is lows in most places aimed 33-37 degrees. While at least limited frost development seems pretty likely especially in some of our far northern/western counties, one of the big question marks is how much frost is able to form within especially our eastern half to 2/3rds of the CWA. Although considered kicking any potential Advisory decision to day shift, ultimately decided to issue a CWA-wide Frost Advisory valid 1-9 AM for our ENTIRE CWA to give folks some heightened/earlier awareness of tonight's frost potential (and more time to potentially cover plants, take them indoors, etc.). This Frost Advisory is best described as "medium confidence" as if it happens to stay even a couple degrees warmer than expected, then little-to-no frost will develop. However, after seeing at least one night with a similarly-ideal cooling potential "overachieve" a few weeks ago and get colder than expected (the morning of April 19th), opted to err on the side of caution and go with the CWA-wide Frost Advisory (uncertainty and all), given that early-spring flowers/early gardens are becoming increasingly- prone to frost impacts. We might also have to watch for some patchy fog development (not currently in our forecast). - SATURDAY-SUNDAY (the weekend): In short, this is a pretty much guaranteed DRY, mostly sunny and seasonably-comfortable weekend as our Central Plains region resides under a pronounced north-south axis of upper level ridging...putting us "safely" well to the west and east of upper level lows centered over both over the eastern and southwestern United States. Temperature-wise, both days look pretty similar with highs mainly low-mid 70s (Saturday night lows in the low 40s most places...too warm for a frost threat). The main difference between the two days are winds. Saturday will feature unusually light speeds (mainly 10 MPH or less) from varying directions as the surface ridge axis passes through. Sunday is then a touch breezier (especially afternoon) with southeasterly sustained speeds around 15 MPH/gusts 20-25 MPH. - MONDAY-THURSDAY: No time for anything resembling "finer details" regarding these four days at this time, and that is probably just fine considering that there remain at least modest differences between the latest ECMWF/GFS regarding the evolution/track of a very slow-moving/lumbering upper low that gradually drifts into the Southern/Central Plains out of the Desert Southwest. As covered above, nothing stands out as an "obvious" severe storm threat for our area at this time, despite our forecast being littered with several (mainly less than likely...less than 60%) chances from Monday afternoon-evening onward. These rain chances will clearly need plenty of fine-tuning as they get closer. Temperature-wise, not looking at any big swings, with highs mainly aimed mid 60s to mid 70s, and lows mainly mid 40s to around 50. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 711 AM CDT Fri May 2 2025 For KGRI/KEAR Airports: - General overview: High confidence the majority of the period features VFR ceiling and the vast majority of the period features dry weather and VFR visibility. That being said, sporadic MVFR ceiling is likely (especially KGRI), and both sites stand a chance of seeing a few passing showers/weak thunderstorms mainly between mid-morning and early evening. Winds should not be a major issue, although the heart of the daytime hours are most favored to feature several hours of gusts 20-25KT (perhaps enhanced by the passing weak convection). More element-specific details follow. - Ceiling/visibility/precipitation potential: At least the first half of the period (daylight hours) period will feature at least a lower VFR ceiling mainly in the 3,500-8,000 ft. range. However, at least a few (perhaps several?) hours of sporadic MVFR also appears fairly likely...especially at KGRI with KEAR perhaps SLIGHTLY less favored for this. Although confidence in the "exacts" of MVFR are still somewhat uncertain, the highest potential should concentrate 15-20Z during which time prevailing MVFR groups are included. During the latter half of the period (this evening- overnight), there is high confidence in VFR, but question marks about whether it is mostly clear or perhaps features a lower-VFR ceiling at times around 5K ft. As for precip potential, these first 9-12 hours feature chances for isolated/scattered rain showers and perhaps a few weak thunderstorms (these chances remain handled with PROB30 groups). Any shower potential should rapidly diminish by/shortly after 00Z. - Winds: The strongest winds will clearly occur during these first 12 hours today...with most of the day featuring northwest-to- northerly sustained speeds 12-17KT/gusts 18-24KT (higher gusts certainly possible in the vicinity of weak convection). During the latter 12 hours this evening-overnight, speeds will rapidly drop off to more than 03-06KT especially 02Z onward. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Frost Advisory from 1 AM to 9 AM CDT Saturday for NEZ039>041- 046>049-060>064-072>077-082>087. KS...Frost Advisory from 1 AM to 9 AM CDT Saturday for KSZ005>007- 017>019. && $$ DISCUSSION...Pfannkuch AVIATION...Pfannkuch