76°F
Updated:
5/17/2022
1:10:27pm

Forecast Discussion
NWS Omaha/Valley, NE
000 FXUS63 KOAX 171736 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1236 PM CDT Tue May 17 2022 ...Updated Aviation Forecast Discussion... .DISCUSSION... Issued at 400 AM CDT Tue May 17 2022 At 400 AM, delinquent anvils from overnight convection in western and central Nebraska were bringing mostly cloudy skies to our region. Radar indicated a couple echos over northeast Nebraska, most of which likely were not reaching the ground. Elsewhere dry conditions prevailed. WAA, from light southerly winds, was keeping temperatures warmer than recent mornings (mid to upper 60s for most). Thunderstorm Threat Today and Tonight: The main forecast concern through the next 24 hours is the potential for severe thunderstorms. Numerous forecast challenges exist, including the affects of any ongoing convection prior to the main event (before 3 PM), timing of convective initiation this evening and the evolution of hazards as storms progress southward overnight. A weak shortwave moving through Nebraska will produce widely scattered shower and thunderstorm activity across the region through 3 PM. This activity should be largely elevated and severe weather is not anticipated prior to 3 PM. This said, any convection in the time window could still modify the local environment and impact how convection develops later this evening. The main show should begin during the 4 PM to 7 PM window as a second shortwave approaches and convergence increases along a stationary boundary in northeast Nebraska. CAMs (HRRR, ARW, FV3 & NAM NEST) are in better agreement with the placement and timing of convective initiation (compared to previous runs), and this was reflected in the 40 dBZ paintball analysis from the 00Z HREF. As such confidence in convective initiation during the 4 PM to 7 PM window is high (70%). Environmental parameters suggest a 1 to 3 hour window for possible isolated supercell activity after storms initiate, then convection should grow upscale into an MCS with the potential for bowing segments or embedded supercells. Thus the initial hazards (4 PM to 9 PM time window) look to be a mix of large hail (to the size of ping pong balls) and downburst winds (gusts to 65 mph). As the likely MCS matures after 9 PM, the primary hazard should be damaging wind gusts of 60 to 75 mph. The hail threat could linger with any embedded supercells, and with better instability (CAPE >2500 j/kg) south of Interstate 80 there is a potential for golf ball or larger hail. An isolated flash flood risk may also develop across southeast Nebraska and southwest Iowa between 10 PM and 2 AM. HREF guidance indicates the potential for localized rain totals of 1.5 to 3 inches south of Interstate 80 during this window, which would be flirting with current 3 Hour Flash Flood Guidance (FFG). A couple tornadoes can`t be ruled out during this event if we can get a an isolated supercell going or a line segment favorably aligned with the 0-3 KM shear. Overall though the tornado potential is lower than the damaging hail or wind threat. The most likely time window for storm activity in the Omaha and Lincoln Metros is 8 PM to 11 PM Storms May Return Thursday Evening: A warm front should lift north across the region Thursday morning as the next significant trough advances into the Northern Plains. This should set the stage for warmer conditions Thursday afternoon (high temps in the upper 80s) and bring limited moisture return by the afternoon. Thunderstorms are possible Thursday evening as a well defined cold front surges through the region. Though the greatest risk for severe weather looks like it will be over southern Minnesota, Wisconsin and northern Iowa, there is some potential for severe weather in our region (see the SPC Day 3 Outlook). Cooler Over the Weekend: A broad area of surface high pressure should settle into the Northern and Central Plains over the weekend. As this occurs a noticeably cooler airmass will overspread the region, sending our temperatures back below seasonal averages. The coolest temperatures are expected Saturday, when afternoon highs may be limited to the lower 60s region wide and morning lows may dip into the 30s across northeast Nebraska. A few light rain showers are possible Saturday morning, but otherwise the weekend should be dry. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1230 PM CDT Tue May 17 2022 A messy aviation forecast is in place for the 18z TAF issuance, with ongoing convection just now exiting the KOFK area, and newer convection bubbling up west of KOMA and just north of KLNK. These current storms are expected to come before another set of storms later this evening after 02z from the northwest, with not a ton of confidence on the exact timing of storms this evening but they should push through rather than linger for long periods of time. After storms have pushed through the area, MVFR and potentially IFR ceilings could develop after midnight and persist through the morning. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Albright AVIATION...Petersen
NWS OAX Office Area Forecast Discussion
Forecast Discussion
NWS Hastings, NE
000 FXUS63 KGID 171751 AFDGID AREA FORECAST DISCUSSION National Weather Service Hastings NE 1251 PM CDT Tue May 17 2022 .DISCUSSION...(Today through Monday) Issued at 343 AM CDT Tue May 17 2022 Overview... The primary forecast concern will center around the enhanced risk for severe weather this evening, which currently appears to be our best chance at precipitation through the week ahead. Our next chance for precipitation will be with a strong cold front late Thursday afternoon and evening, but the better chances with this next system should be northeast of our forecast area. Most areas should be dry Friday through the weekend, with just a slight chance for showers Friday night. Temperatures will be warmer than normal through Thursday with the warmest day being 90s on Thursday. Then a cold front will send highs back down into the 60s for the weekend before we climb back into the lower 70s early next week. Today and Tonight... At just before 4 AM we have a few showers and thunderstorms trying to develop and forecast models indicate this activity may increase over the next several hours before sliding east of our area by mid to late morning. There should then be a prolonged lull in precipitation with mostly sunny skies from late morning through late afternoon for most locations. This will allow the atmosphere to destabilize and then thunderstorms will form along a northeast to southwest oriented cold front this evening primarily after 6 PM. Thunderstorms should really increase across the coverage area this evening between 6-10 PM and then slide east southeast. Forecast models have been coming into better agreement in that this will likely be a fairly widespread and appreciable precipitation event across our forecast area with many locations having a shot at 0.50 to 1.5 inches of rainfall. Would not be surprised in a few isolated 2 to 3 inch rainfall amounts where stronger storms train over the same area. Severe thunderstorms could impact the area through 1 AM before most of them pass southeast of our forecast area. MUCAPE values based on several different models will likely average between 2500-3500 J/KG with 0-6km deep layer shear values of 30-40 kts, which would support higher end severe weather. At this time large hail to golf ball size, maybe larger, and wind gusts to 70 mph seem likely in at least some of the stronger storms. The storms will likely quickly form into a line and can not rule out a weak QLCS tornado or two, but the low level wind shear is not very impressive until well after dark when storms will probably begin to become more elevated by that point. Wednesday... This will be a quiet weather day between systems with zonal flow to perhaps a slight upper ridge leading to dry conditions and highs around 80. Thursday... The large upper trough will take a far northern track across the northern plains. This is not a good track for us to see a lot of precipitation as most of the dynamic energy with this system will be well to our north. However, the strong cold front and plenty of instability just ahead of the front could be enough to generate a strong line of thunderstorms primarily during the evening hours, but hard to tell how far southwest along the front the storms will form this far out. Right now the best chance for thunderstorms will be across our northeastern zones and points northeast from there, but this could change. It will certainly be warm and moist ahead of the front with highs in generally in the 90s. The SPC slight risk area is northeast of our forecast area where the coverage of storms should be greater. Confidence in storms across our area is still fairly low. Friday through Sunday... For the most part we`ll dry out as we get into dry and cooler northwesterly upper level flow on the back side of the departing storm system. However, we do have just a slight chance for some light rain Friday night in association with the upper trough, but most folks will probably see little to no precipitation. This will send highs back down into the 60s for Friday and Saturday, possibly getting back close to 70 again by Sunday. We may have to watch out for a slight chance of a light frost Saturday morning May 21st across our northwestern zones, right now our lows are forecast to be in the mid to upper 30s in Ord and lexington so it could be close. Monday... We have a slight chance for precipitation with a weak passing shortwave. Highs should begin to warm back up and possibly into the 70s for most areas. && .AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Wednesday) Issued at 1240 PM CDT Tue May 17 2022 VFR conditions persist at both terminals through the rest of this afternoon. Southerly winds are expected to continue, becoming slightly south-southwest by mid-afternoon as the remnants of decaying thunderstorms move through the area. Heading into late this afternoon into evening, a cold front is expected to cross the region, kicking off showers and thunderstorms. A few of these may become strong to severe with hail and strong winds being the main threats. Have put vicinity storms in the forecast for now as there remains some uncertainty on where the front will be located this evening. Conditions are expected to be VFR/MVFR through this time with thunderstorms bringing short periods of reduced visibility. Conditions improve after midnight with northerly winds 5-10kts expected through the remainder of the forecast period. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ DISCUSSION...Wesely AVIATION...Wekesser
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