Area Forecast Discussion
Issued by NWS Hastings, NE
Issued by NWS Hastings, NE
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354 FXUS63 KGID 290034 AFDGID Area Forecast Discussion National Weather Service Hastings NE 734 PM CDT Fri Jun 28 2024 ...Short Term and Aviation Update... .KEY MESSAGES... - There is a Marginal (1/5) to Slight (2/5) Risk for severe thunderstorms this evening for the area, with wind being the main threat with any storms that are able to develop. A Marginal Risk for Excessive Rainfall has also been put out for the area. - The weekend is looking pleasant with cooler temperatures and periodic chances (20-50%) for showers and thunderstorms mainly Saturday night through Sunday. - The weekend is looking pleasant with cooler temperatures and periodic chances (20-50%) for showers and thunderstorms mainly Saturday night through Sunday. - Areas north of Interstate 80 have been outlooked in a Day 4 risk area for severe weather by the Storm Prediction Center. This will be something to keep an eye on as we get closer to the event. - Independence Day will be hot with highs ranging from the mid-80s to low 90s. There is a 20-30% chance of showers and thunderstorms. && .UPDATE... Issued at 734 PM CDT Fri Jun 28 2024 -- Various thoughts on thunderstorm/severe potential through the rest of the evening-overnight: - As largely expected, we have remained storm-free SO FAR this evening, with robust severe storms along the very leading edges of the synoptic cold front firing up "safely" southeast of our coverage area (CWA) over northeast KS. Meanwhile, any (so far weak) storms developing off the High Plains of the NE/CO/KS border area have remained well to our west. -- Between now and roughly 2 AM: - Obviously the MILLION DOLLAR QUESTION is whether (and to what degree) storms and possible severe weather will impact our CWA? - Unlike last evening (when by now it was becoming quite clear that we were not going to see much mainly due to stronger capping), tonight`s capping situation is perhaps a LITTLE weaker (but with 700 millibar temps still a good 12-13C). Otherwise, the environment is certainly supportive of at least isolated severe, with mixed-layer CAPE solidly 1500-2500 J/kg and deep-layer/effective shear 40+KT (these parameters would support east-southeast tracking supercells. - Leaning on the last few HRRR runs as much as anything (usually a reasonable bet in the very short-term), it has trended a bit more aggressive with its depiction of isolated to perhaps scattered storms (a few severe?) invading our western counties 9-11 PM, and then gradually weakening as they slide farther east into our CWA between 11 PM-2 AM. Interestingly, the HRRR focuses on two separate areas for greatest storm potential: 1) one near/south of the KS border (which seems most reasonable based on upstream radar trends)...2) another mainly north of I-80, which seems a bit more questionable but also plausible, as RAP forecast soundings suggest our northern zones will be most prone to realizing elevated instability release around 1000 J/kg with storms based up around 750 millibars (these would likely be more of a hail threat with perhaps penny to quarter size potential). The former area near/south of the KS border would (in theory) pose more of a damaging wind threat...particularly if they organize a surging cold pool. - PLEASE NOTE: because of residual capping/weak forcing aloft, it is also quite possible that storm coverage/intensity again "underachieves" this evening, which is why chances/PoPs have been intentionally held UNDER 50% at this time. -- After roughly 2 AM: - In one change from previous forecast, have lingered/added at least slight PoPs (20%) to the entire CWA through the late night/early-AM hours, as both HRRR/NAMNest are now more suggestive that at least isolated storms (possibly marginally- severe?) could persist especially within counties along/north of I-80 even through around sunrise. - It is possible that small shower/thunderstorm chances may even need lingered into the official Saturday daytime forecast period (which starts at 7 AM) mainly in our northern zones, but with higher-res models suggesting that even elevated instability should be on a downward trend by then, will likely defer to overnight forecaster to decide whether this is warranted. && .DISCUSSION... Issued at 401 PM CDT Fri Jun 28 2024 The heat continues this afternoon across portions of south central Nebraska and north central Kansas. Current temperatures are primarily in the 80s to low 90s, with a cold front pushing through the state. The front has moved through the Tri-Cities, with winds mainly out of the north to northwest. A few showers moved through the area earlier today, with additional chances mainly after 7PM. Thunderstorms will start across the western portions of the area, expanding in coverage to the east as the evening progresses. SBCAPE of 2000+ J/kg, and MLCAPE of 1000+ J/kg are expected along with DCAPE values of 1100+ J/kg, ML lapse rates around 7 C/km, and steep low-level lapse rates in the west. The main concern for any severe weather this evening will be wind. Some hail, an isolated tornado, and localized flooding may also be a concern. The Storm Prediction Center has outlooked portions of the area for either a Marginal Risk (1 of 5) or Slight Risk (2 of 5) for tonight. The main areas of concern for severe weather will be along and ahead of the front (which includes the southern and western portions of the area. Additionally, the Weather Prediction Center has outlooked us in a Marginal Risk for Excessive Rainfall for this evening. Heading into the overnight hours, thunderstorm chances (20-30%) persist, with strong to severe storms not expected. The cold front will bring in some cooler air for the weekend, making conditions very pleasant. Expected high temperatures will range from the mid- 70s to low 80s for Nebraska and the upper 70s to low 80s for Kansas. Lows will be primarily in the 50s and 60s on Sunday morning, and the 60s on Monday morning. As far as precipitation chances are concerned for the weekend, a few showers and thunderstorms may linger into the morning on Saturday. The rest of the day is looking dry, with additional showers and thunderstorms late. Showers and thunderstorms will be possible again on Sunday. Monday, an upper ridge moves to the east, with southwest flow in place over the High Plains. Temperatures are expected to climb with warm air advecting into the region. The current forecast as most areas in Nebraska in the 90s and north central Kansas in the 90s to around 100 degrees. Heat index values may approach or exceed 105 degrees, which may result in heat headlines needing to be considered. The heat is expected to continue into Tuesday, although, slightly cooler temperatures are expected. Periodic shower and thunderstorm activity is expected through mid- week. Any one area may not see shower and thunderstorm activity each day. The Storm Prediction Center has put out a Day 4 Outlook for severe weather for areas along and north of Interstate 80. The Weather Prediction Center has outlook the northeastern portion of the Hastings CWA with a Marginal Risk for Excessive Rainfall. For those planning on outdoor activities for Independence Day, there is a 20-30% chance of showers and thunderstorms through the day. Daytime highs are currently forecast for the mid-80s (north) to low 90s (south). Continue to monitor the forecast for the latest updates. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 734 PM CDT Fri Jun 28 2024 For KGRI/KEAR Airports: - General overview: Odds strongly favor VFR ceiling/visibility and rain/thunderstorm-free conditions through the vast majority of the period. That being said, there will be at least a 3-4 hour "window of opportunity" for thunderstorms later this evening (perhaps strong to severe?), and there is also a low chance for at least a brief MVFR ceiling late tonight behind a passing cold front. Wind-wise, aside from any possible thunderstorm-induced outflow, the overall-strongest breezes with gusts 20-25KT will occur out of the north during the day Saturday. - Ceiling/visibility/rain/thunderstorm details: Although far from a "sure thing", there is just enough support for the possibility of a broken line or cluster of thunderstorms to pass through from west-to-east this evening, that have opted to introduce a generic "vicinity thunderstorm" (VCTS) 02-06Z KEAR/03-06Z KGRI. IF storms occur, there is a low probability that they could be strong to marginally-severe, with the main issue being strong outflow winds 40-50KT. Will closely monitor this possibility and amend for possible TEMPO and/or prevailing thunderstorm inclusion as needed. Beyond 06Z, there is still a very low (around 10%) chance of spotty shower/weaker thunderstorm activity through around 12Z, but this chance is low enough to omit from TAFs at this time. The other possible "wrench" in things are at least minor hints of at least 1-2 hours of possible MVFR ceiling late tonight in some (but not all) model data. Have "hinted" at this with a SCT015 group 06-12Z, but far from enough confidence to go prevailing MVFR at this time. - Wind details: Aside from any possible much stronger thunderstorm-related outflow this evening, winds during these first 12-hours will be fairly light (under 10KT out and mainly northerly). However, the latter half of the period will be a bit breezy out of the north, with the majority of Saturday daytime featuring sustained speeds around 15KT/gusts 20-25KT. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ UPDATE...Pfannkuch DISCUSSION...Wekesser AVIATION...Pfannkuch