492 FXUS63 KGID 291718 AFDGID AREA FORECAST DISCUSSION National Weather Service Hastings NE 1218 PM CDT Mon Aug 29 2022 ...Aviation Update... .DISCUSSION...(Today through Sunday) Issued at 543 AM CDT Mon Aug 29 2022 -- General overview/highlights of the entire 7-day forecast (including all discussion of Days 3-7 Wed-Sun): 1) Above ALL else (and unfortunately for drought concerns): an overwhelmingly dry weather pattern looks to prevail through the 7-day (and probably beyond per latest CPC 8-14 day outlook): Although there will surely be some spotty/hit-or-miss shower/thunderstorm activity (including right away today and then perhaps again around Wed-Thurs, there is simply absolutely nothing on the foreseeable horizon to "latch onto" for meaningful, widespread rain. This is obviously directly tied to the fact that there are just no organized, large scale low pressure systems to be found. Very generally speaking, this next week will be characterized by our local area being "caught in the middle" of a somewhat blocky/disorganized upper air pattern. The one constant will be a persistent large scale western CONUS ridge, and while the first part of the week will feature a gradually departing large scale trough over the northeast CONUS, by late in the week/this weekend another upper ridge will gradually build into the southeast CONUS, effectively reinforcing the relatively stagnant, blocked-up pattern here in the Central Plains. Our only hope for rain will hinge upon very subtle, difficult to pin down upper disturbances, a few of which could maybe at least set off limited activity given that mid level temps should at least not be overly-warm (meaning capping not overly strong). All this being said, anybody in our CWA that measures more than a few hundredths of rain through this next week (especially beyond today) should consider themselves very fortunate. 2) Temperature overview: Those watching our forecast issuances closely the past several days may have noted that temperatures in especially the Days 4-7 range keep trending warmer as they get closer in time, and that trend continued with this latest forecast (highs for particularly Fri-Sun were just bumped up a good 2-4 degrees). The net result is that while nothing during the next week appears as downright hot as yesterday was, confidence is high in a rather persistent (and consistent) stretch of seasonably warm late summer weather (technically about to be early-meteorological fall). More specifically, each of the next 7 days look to feature highs at least mid-upper 80s, along with a smattering of at least low 90s (some mid 90s in typically warmer south-southwest zones). Overnight lows on most nights during this next week should bottom out in the low 60s, although a shot of seasonably-dry dewpoints arriving over these first 48 hours will allow for more in the way of 50s (especially tonight). 3) Focusing more shorter-term...cooler today but still seasonably- warm: For sure, highs today will average at least 6-10 degrees cooler than yesterday's downright hot readings, but we are still talking mid-upper 80s most areas and even some low-mid 90s in our KS zones (meaning most areas a good 3-5 degrees above normal for the date). 4) A somewhat cosmetic (but worth mentioning) change to today's forecast: While 24 hours ago our forecast for today mentioned nothing more than a "slight chance of sprinkles" (and for many areas this may still be the case), there now appears to be JUST ENOUGH elevated instability to justify a low-end chance for very spotty, almost certainly weak thunderstorm activity. These chances will gradually fade from north-to-south as the day wears on, and even our extreme southern KS zones should be void of any rain chances (PoPs) by around midnight. -- With the main takeaway messages covered, will finish up as usual with some shorter-term details solely focused on these first 48 hours/4 forecast periods: - Current/recent weather situation as of 430 AM: Although the majority of our coverage area (CWA) has (as expected) gotten through the last 12 hours dry, mainly parts of our KS zones (which actually had a rogue severe-warned storm last evening) and also our northern zones north of I-80 (which have seen scattered showers/weak storms much of the late night/early AM) have at least received a bit of needed rain (although most affected areas no more than a few tenths of an inch). As of this writing, the most concentrated cluster of pre-dawn convection has departed our far northeast counties, but a spotty ribbon of showers/few weak storms extends back to the west, while other very isolated activity is noted near/south of the state line. Although a glance at basic most-unstable CAPE fields would suggest halfway decent instability of at least 500-1000 J/kg across most of our CWA (and thus potential for stronger storms), upon closer inspection of soundings most of this potential instability is "capped off" by warm mid level temps (700 millibar temps generally 12-13C). As a result, most storms out there are VERY high based and rooted near to even above that 700mb level (generally 10K+ft.), where available CAPE is only averaging a few hundred J/kg at best (and thus keeping storms on the weaker side...small hail at the very most). In the big picture of the mid-upper levels, water vapor satellite and short term model data confirm that we are barely catching a glancing blow of forcing along the extreme south- southwest reach of influence from a vigorous trough/vort max centered just north of the MN/Canada border...while a broad upper ridge dominates the western CONUS to our west. At the surface, a weak cold front that passed through most of our CWA late yesterday afternoon-evening has temporarily stalled out near the state line. To its north, our Neb zones feature light northerly-to- easterly breezes (5-10 MPH tops), while most of our KS zones are hanging on to a light southerly breeze. Skies are mix of clear skies and mid- high level clouds, and overnight low temps are on track to bottom out mainly in the mid-upper 60s (but ranging from low 60s far north to low 70s especially far southeast). - Today (through around 7 PM): Clearly the main stories are the modestly-cooler temperatures compared to yesterday (albeit still quite warm), and also the very spotty, low-end (for any given location) chance for a shower/weak thunderstorm (but the vast majority of the CWA unlikely to see much more than a sprinkle at best). In the mid-upper levels, a reinforcing disturbance will drop down the back side of the aforementioned Upper Great Lakes region trough, which here at the surface locally will effectively give the aforementioned front currently near the state line more of a southward nudge. Meanwhile, the axis of fairly weak uncapped/available instability that currently resides over nearly our entire CWA to start the day will gradually diminish southward with time. However, until it does so, the slight chances for spotty showers/weak storms (small hail potential at most) will continue. Generally though, have a dry forecast returning to most of the northern half of our Neb zones by early afternoon, most of our southern Neb zones by mid- late afternoon, and to most of our KS zones by early evening. As the meager rain chances diminish, so will batches of passing mid- upper clouds, with increasing sunshine taking over from north-to- south as the day wears on. Getting back to the surface situation, the stalled front should finally clear our KS zones by around mid- day, meaning that our entire CWA will see mainly northeasterly breezes averaging generally 10-15 MPH (some gusts to around 20 MPH especially south). Temperature-wise, made the slightest upward nudge to highs most areas, aiming mid-upper 80s most areas but low to even mid 90s especially in our southern-most 3 KS counties. Fortunately though, even there heat index should hold under 100. Also at the surface, we'll see a gradual invasion of increasingly- dry air from north to south, with dewpoints by mid- late afternoon in the 50s most area, but ranging from 40s far north to some more humid 60s far south. - This evening-overnight (beyond 7 PM): For the vast majority of the CWA, this is truly a guaranteed dry period, especially given that the main surface frontal zone should reside 1-2 counties south of our far southern CWA by early evening. Immediately along this front just to our south, a fairly robust, at least broken line of strong to severe storms will likely unzip across parts of central-eastern KS. While our far southern zones should be "safe" from this surface-based activity (albeit a rather close call), models suggest that there will be just enough of a northward push of elevated instability mainly between around sunset-midnight to MAYBE allow a few weak storms to clip southern parts of our southern-most 3 KS zones and thus have slight PoPs hanging on there through the evening. Post- midnight, however, have fairly high confidence in our going CWA- wide dry forecast. Once any convection finally fully departs, the rest of the night will be marked by a good surface high pressure radiational cooling setup featuring clear skies, light northerly breezes and increasingly dry air filtering in from the north (most of our Neb zones should have dewpoints in 40s/low 50s by sunrise Tues). As a result, tonight's low temps should be the overall- coolest of the next week, aimed mid-upper 50s most areas, but ranging low 50s far north to around 60 far south. All in all, a very pleasant start to Tuesday. - Tuesday daytime: Quite possibly the most straightforward forecast period of the entire week. In short, high confidence in a very sunny and guaranteed dry day, and although it will again be seasonably warm (highs mid 80s to low 90s), the airmass will be seasonably dry with dewpoints only topping out upper 40s-low 50s for most of the day...so fairly comfortable despite the slightly above average warmth. Winds will also be fairly light as surface high pressure slides through, with sustained speeds averaging around to below 10 MPH out of a northerly to easterly direction. - Tuesday evening-night: Almost assuredly dry conditions continue under clear skies. Although light breezes will flip around to southerly in the wake of departing surface high pressure, the presence of a continued seasonably-dry airmass will again allow low temps to drop into the upper 50s to around 60 all areas (similar to Monday night's lows in our southern zones but at least a few degrees warmer than tonight in our central/especially northern zones). && .AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Tuesday) Issued at 1215 PM CDT Mon Aug 29 2022 VFR conditions are forecast for this TAF period. Main area of any lingering isolated showers/storms has shifted to the south of the terminal areas, and any redevelopment later today is expected to remain to the south. Winds this afternoon look to remain northeasterly, can't rule out a gust near 20 MPH over the next hour or so, but overall speeds look to be around 10 MPH. This evening/overnight, lighter and more variable winds are expected, then turning to the north after sunrise Tuesday. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ DISCUSSION...Pfannkuch AVIATION...ADP