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Office: LBF
FXUS63 KLBF 222146
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
446 PM CDT Sat Jun 22 2024

.KEY MESSAGES...

- Some potential for isolated strong to severe thunderstorms
  late Sunday and again late Monday along/east of Highway 83.

- Hot on Monday with potential for hazardous heat index values
  across central and western Nebraska.

- Thunderstorms with increasing potential for locally heavy
  rainfall mid to late week.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 440 PM CDT Sat Jun 22 2024

High pressure building down into eastern Nebraska tonight will bring
quiet weather to the region with lows generally around 60. As
the high quickly moves off to our southeast return flow on the
back side of the high will allow southerly winds to usher hot
air back into central and western Nebraska by tomorrow as
afternoon readings peak well into the 90s but a bit cooler to
the northeast. As a dry line starts to push in from the west
during the afternoon unstable air will pool along and east of
Hwy 83. There is some capping in the core of the greatest
instability along the Hwy 183 corridor, lapse rates aloft are
not overly steep, and the synoptic environment is not
particularly robust in this conditional environment but forcing
from the dry line and a low level jet starting to nose into the
region from the south early Sunday evening look to be enough to
support at least isolated thunderstorm development despite most
mesoscale guidance showing reluctance to develop convection.
Storms that do manage to form will have 0-6km bulk shear around
30kt and modestly curved hodographs aid organization with enough
chunky CAPE aloft to support a large hail threat and DCAPE
values of 1500J/kg with steep low level lapse rates in a hot
boundary layer will aid efficient wind production for a damaging
wind threat. SPC Day 2 Marginal Risk centered on south central
Nebraska seems about right and will have to monitor outflow
boundaries capable of initiating convection as the propagate
away from this area. The convective threat will wane early
Sunday night with loss of diurnal heating, some dissipation of
elevated instability, and the dry line retreats westward. Lows
Sunday night will generally be in the middle 60s.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 440 PM CDT Sat Jun 22 2024

Monday is shaping up to be hot with EFI/SoT guidance showing a
trend for well above normal heat across central and western
Nebraska. Anticipate triple digit highs along and south of
Interstate 80 with readings well into the 90s further to the
north, potentially elevating heat index values to hazardous
levels. Will monitor heat potential closely to see if headlines
become warranted.

The convective environment remains conditional on Monday due to
some capping, though the dry line pushing eastward again during
the afternoon followed by a cold front moving through late may
provide enough forcing to trigger convection. There will be a
substantial pool of instability mainly east of Highway 183 with
CAPE values approaching 4000J/kg along with steep low level
lapse rates and substantial DCAPE values around 2000J/kg but
shear is not as robust with small hodographs and 0-6km bulk
shear generally in the 20 to 30kt range. Anticipate widely
scattered storms will develop with best potential for severe
storms east of Hwy 83 from south central up toward northeast
Nebraska with primarily a wind/hail threat with loss of diurnal
heating and passage of the cold front bringing an end to
convection overnight.

Thereafter, the High Plains will remain under a mean ridge with
a series of waves moving through the northern tier of states
periodically suppressing the amplitude of the ridge. Ensemble
guidance shows an increase in precipitable water values during
the latter portion of the workweek with values rising above the
90th percentile as moisture with a tropical connection streams
up from the southwest. This will continue our warm temperatures
and bring potential for diurnally biased showers/thunderstorms
each day from midweek onward, along with potential for excessive
rainfall working up form the southwest by the end of the week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1255 PM CDT Sat Jun 22 2024

VFR conditions expected to persist at TAF sites through this
valid period.

Earlier low CIGs have scattered out and expect scattered clouds
with a rising trend through this afternoon. Mid clouds increase
tonight but any hints for low clouds and/or fog are confined to
locations further to the southeast. Any isolated showers or
thunderstorms Sunday will hold off until after this valid
period.

Winds will be northwesterly/northerly and a bit gusty under 20kt
early this afternoon, followed by light and variable conditions
through tonight. Winds then become southerly Sunday with some
low end gusts 15 to 20kt developing by late Sunday morning.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SHORT TERM...MBS
LONG TERM...MBS
AVIATION...MBS



Office: OAX FXUS63 KOAX 222059 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 359 PM CDT Sat Jun 22 2024 .KEY MESSAGES... - Flooding of the Missouri River tributaries in southeast South Dakota and northwest Iowa will lead to increased water flow into the Missouri River downstream of Sioux City. Flood warnings are in effect along the Missouri from Decatur to Rulo beginning early next week. - There is less than a 5% chance of severe thunderstorm development in southeast Nebraska through early evening, with damaging winds the primary hazards. - The hottest temperatures so far this year are expected Monday and possibly Tuesday, with heat index readings of 100 to 110. - There will be additional storm chances next week, with occasional severe weather and heavy rainfall possible, particularly on Tuesday and Friday. && .DISCUSSION... Issued at 358 PM CDT Sat Jun 22 2024 Quasi-zonal flow prevails across the northern plains this afternoon, with a short wave feature moving eastward into the Great Lakes region. An attendant frontal boundary is slowing moving through the forecast area, so far only marked by a windshift and slightly cooler temperatures. Diabatic heating will allow SB/MUCAPE to increase into the 1500-2500 J/kg range by late afternoon with bulk shear 30-35kt. Diabatic forcing combined with weak large scale forcing and low level convergence may be sufficient to develop isolated thundestorms late this afternoon, generally south and east of Harlan IA to Omaha- Council Bluffs to Pawnee City line. Given bulk shear values on the low side, it may be difficult to storms to sustain updrafts, thus any storm that reaches severe limits may collapse producing isolated damaging wind gusts. The front is expected to move south of the forecast area early this evening, effectively ending the severe weather threat. The rest of the evening will be characterized by clearing skies and light northwest winds, with temperatures falling into the 60s. Sunday through Tuesday: Upper level riding amplifies as aforementioned short wave feature carves a long wave trough across the eastern U.S. bisecting southern tier H5 dome. The sensible weather effect across the forecast area is a dramatic increase in temperatures, especially Monday. Temperatures on Sunday will be about 5 degrees above normal, with upper 80s and lower 90s expected, and heat indicies in the mid 90s. Monday will be the sizzler of the week, with high temperatures in the upper 90s to lower 100s and heat indicies 100 to 110. There still is some spread in the forecast guidance, with half the at least one of the ensemble clusters indicating less ridging. 75+% confidence in heat headlines being issued in the next 24 hours. Tuesday, the signal is a little mixed. A vortex moving across the central Canadian provinces has a slight reflection in the form of a diffuse upper level disturbance that moves across the central plains Monday night into Tuesday, dragging another weak cold front across the region. Synoptic models and medium range ensemble clusters indicate the development of a MCS that will move across the area, mainly affecting northeast Nebraska and western Iowa. Convective cloud debris and cooling from the passage of the front may impact the level of warming, except for southeast Nebraska and southwest Iowa. Still, NBM 25-75% temperatures near or above 90 in most locations. Redevelopment of storms along the front later in the afternoon appears possible, which could further limit temperatures. Rainfall amounts do not appear excessive at this time, with model QPF a quarter inch or less, thus would not expect flooding situation to be exacerbated. However, precipitable water values will be in the 75% of climatology, thus isolated heavy rainfall may be possible. Wednesday Through Saturday: A relatively quiet weather day on Wednesday, with slightly above average temperatures and no precipitation expected. A large scale trough develops across the western U.S. coast Thursday, with medium range deterministic and ensembles ejecting systems quickly eastward Friday and Saturday across the northern U.S. and southern central Canada. One or more convective complexes will affect the area, with the possibility of severe weather and heavy rainfall, with the grand ensemble indicating a 20 to 40% probability of sufficient CAPE and shear for severe weather on Friday. Temperatures will trend slightly above average Wednesday through Friday, with more seasonable temperatures on Saturday. Similarly the probability of 1 inch or greater rainfall occuring somewhere across the region is 30 to 50%. The additional rainfall could delay the recession of the Missouri river if realized. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1248 PM CDT Sat Jun 22 2024 MVFR ceilings at FL020-025 will linger until 19z-20z at KOFK, with diurnal mixing and frontal passage leading to VFR ceiling FL040, and gradually becoming scattered. VFR conditions will prevail at KLNK and KOMA with SCT to BKN clouds at FL040-060. Front moving across the forecast area will cause southwest to westerly winds 10 to 20 with gusts up to 25kt to veer to a northwesterly direction between 20z and 22z. Any remaining low clouds will dissipate by 00z-01z with northwest winds slackening below 10kts, then becoming light and variable after 08z. There is a 15 to 25% probability of MVFR visibilities 3SM to 5SM developing 10z-12z, but will leave out for now. && .HYDROLOGY... Issued at 358 PM CDT Sat Jun 22 2024 Flood warnings have been posted along the Missouri River downstream from Sioux City to Rulo. The successive river forecasts during the past 24-36 hours have lagged the onset of flooding and crests, forecasts are tracking with observations more closely. This will be the first time since 2020 that the Missouri has been in flood along its entire reach in the HSA. Additionally flooding is occurring along Ponca Creak from its headwaters to Verdel, with some indications that the river could recrest again based on the National Water Model. River levels also are above action stage along the Platte between Schuyler and North Bend, Loup upstream of Columbus and Clear Creek. Fortunately there will be no precipitation in the short-term to affect rivers in the next 24-48 hours, but precipitation Tuesday and onward could impact the recession of the Missouri, and cause other area rivers to rise from Wednesday onward. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Fortin AVIATION...Fortin HYDROLOGY...Fortin
Office: GID FXUS63 KGID 222054 AFDGID Area Forecast Discussion National Weather Service Hastings NE 354 PM CDT Sat Jun 22 2024 .KEY MESSAGES... - Flooding continues in some areas north of I-80 as a result of heavy rainfall Friday night. - Isolated to widely scattered thunderstorms expected Sunday afternoon/evening and again Monday evening. Marginal risk for severe weather both of these days. - Advisory-level heat (heat index 105+) is possible for portions of the area both Monday and Tuesday. - More widespread chances for rain and thunderstorms return mid to late next week. && .DISCUSSION... Issued at 330 PM CDT Sat Jun 22 2024 A cold front has moved through the forecast area, ushering in breezy northwest winds and some pesky cloud cover. Despite this, temperatures have still risen to near our climatological normals in most locations (90s and low 90s). Skies continue to clear this evening, and any thunderstorm development should stay to our south...which is good news for areas that are still experiencing runoff flooding from last night. A warning trend starts on Sunday as upper ridging builds in from the west. Southwestern portions of the area could push 100 degrees, and 90s are expected for most of the rest of the area. CAMs show a few thunderstorms developing mid to late afternoon over western portions of the area, but I expect coverage to remain pretty isolated due to capping/warm midlevel temperatures. Any storms that do develop would be able to tap into MLCAPE around 2000 J/kg and effective shear of 30-40kts and potentially produce some severe hail/wind. Monday still appears to be the warmest day of the week, with the entire area making a run into the upper 90s and low 100s. Heat index values may reach/exceed advisory criteria (105 degrees) in some spots. Again, there is a chance for a few spotty storms, some of which could be marginally severe, late Monday afternoon through the evening. A front moves into the region on Tuesday, but timing of this feature is still somewhat uncertain. The NBM has trended warmer compared to 24 hours ago, and parts of our area (especially KS) could see another day of 105+ heat indices. Wednesday through Friday will be "cooler" as a series of shortwave break down the upper ridge. That said, highs are still expected to reach/exceed climo for much of the area each of these days. These shortwaves will also bring us better chances for more widespread rain/thunderstorms, especially Thursday night through Friday night. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1231 PM CDT Sat Jun 22 2024 For KGRI/KEAR Airports: MVFR conditions are ongoing at both terminals as low level clouds continue to move into the region from the north. There are some mid-level clouds moving in from the southeast, as seen on visible satellite imagery. Ceilings will bounce around over the next couple of hours as a few waves of lower clouds continue to move through. Ceilings are expected to improve to VFR late this afternoon and into this evening. North winds remain around 10-15kts for the early part of this afternoon, falling under 12kts by mid-afternoon. Overnight, winds will become light and variable, before switching to the south around 5-10kts by sunrise. Expect the possibility of a few low to mid-level clouds around sunrise, as some patchy fog or low stratus may move in. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ DISCUSSION...Mangels AVIATION...Wekesser