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Office: LBF

FXUS63 KLBF 231807
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
107 PM CDT Wed May 23 2018

.SYNOPSIS...
Issued at 345 AM CDT Wed May 23 2018

H5 analysis from tonight had a closed low along the Utah/Nevada
border, with a trough extending south into northern portions of
Baja California. North of the low and trough, a ridge of high
pressure was present across western Canada. This ridge extended
north into northern portions of the NW Territories of Canada. East
of these features, a low amplitude trough of low pressure was
present across Quebec, south into the Mid Atlantic states. East of
this trough, high pressure was anchored over the western
Atlantic. At the surface, a trough of low pressure extended from
northeastern Wyoming, south into eastern Colorado. A warm front
extended across southern South Dakota. A secondary area of low
pressure was noted over southeastern Colorado. Winds were from the
south overnight, and with partly to mostly cloudy skies, readings
as of 3 AM CDT ranged from the middle 60s to around 70 degrees.

&&

.SHORT TERM...(Today and tonight)
Issued at 345 AM CDT Wed May 23 2018

Thunderstorm chances and the threat for severe storms will be the
main forecast challenges over the next 24 hours. The previously
mentioned upper level low, will lift northeast into southern
Montana today, deepening the surface trough along the front range
of Wyoming and Colorado. East of the trough, southerly winds will
increase with breezy conditions expected this afternoon. Good
mixing will facilitate highs well into the middle and upper 80s
this afternoon. By late afternoon, a decent shortwave will lift
across the central Rockies, emerging onto the northeastern
Colorado Plains. Strong southerly winds crossing the Palmer
Divide, will result in subsidence on the north side of the divide,
enhancing a dryline bulge over nern Colorado by 21z this
afternoon. The latest NAM12, WARW, and HREF products, initiate
convection on the nose of this dryline bulge, then lift this
activity north northeast into the Nebraska panhandle through mid
evening. Additional convection is expected to develop from mid
evening into the overnight hours east of the panhandle into North
Central Nebraska. The best chances for storms overnight will be
across northern portions of the forecast area where the nose of an
H85 jet streak sets up overnight. As for the threat for severe
storms, the greatest threat will be over the northwestern forecast
area INVOF the surface trough. Modest deep layer shear of 30 to
40 KTS in the northwestern forecast area, should support some
strong to severe storms with the main threat being from large hail
and damaging winds. The severe threat will diminish east of the
panhandle, as deep layer shear weakens east of highway 83.

.LONG TERM...(Thursday through Tuesday)
Issued at 345 AM CDT Wed May 23 2018

As an upper low comes onshore in California and the main trough digs
across the Desert Southwest, a ridge builds over the Great Plains.
The pattern of amplifying southwest flow aloft helps lead to the
warmest stretch of the season so far for western Neb. Meanwhile, a
weak cool front crosses the forecast area Thursday, setting the
stage for additional thunderstorm development before high pressure
takes over. The next lee side low lines up for late in the holiday
weekend.

Thursday... Continued chc TSRA east of Hwy 83, along/ahead of the
front. Can't rule out a strong or briefly severe storm on the
account of good surface moisture (dew points near 60F) and
instability (MUCAPE 1500+ j/kg, LI near -7). However, shear is
meager (0-6km up to 30 kts) and the wind profile is primarily
unidirectional. Made little change to max temps in the mid/upper
80s, which is close to a MAV/MET blend. H85 temps approach 25C
across the Sandhills as there is little CAA post fropa.

Friday and Saturday... The building upper ridge and surface high
leads to consistent southerly flow, fair skies, and deep mixing
(above H7). The result is widespread highs near 90F, almost 20
degrees above normal and nearing record heat for late May. NAEFS
ensembles indicate H85 temps near the 99%ile, supportive of the warm
forecast. However, hedged toward the slightly cooler end of guidance
Saturday due to dew points rising to 60F again. If return flow of
moisture is delayed and dry air sticks around longer, could be
within reach of record highs.

Sunday and beyond... Temps stay seasonably warm but are tempered a
bit as precip chances increase. Confidence is greater for strong
moisture advection ahead of the slowly approaching upper low and
developing sfc trough.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 106 PM CDT Wed May 23 2018

The main aviation concern for the next day will be the chance of
some rain showers and thunderstorms again tonight. Thunderstorms
could develop as early as late afternoon, however, the best chance
will be between 8pm CDT and 2am CDT. Low level wind shear is also
expected at both sites as the low level jet intensifies overnight.
VFR conditions return on Thursday morning as ceilings remain well
above 5000 feet and visibilities stay above 6 SM.

&&

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

$$

SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Snively
AVIATION...Kulik



Office: OAX FXUS63 KOAX 231714 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1214 PM CDT Wed May 23 2018 .UPDATE... Issued at 1210 PM CDT Wed May 23 2018 Boosted highs about 1 degree from previous forecast. This brings us to 90 at Omaha and Lincoln, which we haven't hit at these two locations since September 23, 2017. && .SHORT TERM...(Today through Friday) Issued at 230 AM CDT Wed May 23 2018 The summer-like pattern over the next several days will mean above normal temperatures, but also the risk for hard to pin down storms. The h5 low over the Nevada/Utah border will lift northward toward Montana through Wednesday night. Stronger areas of convection are north of the low level jet and extend from South Dakota into southwest Minnesota and northern Iowa. A shortwave near the Colorado/Kansas border will lift north this morning with isolated thunderstorms over central Nebraska. Not sure if any of these will make it into northeast Nebraska. There is an ill-defined boundary near the NE/SD border and did keep the small pops in there. Over the next few days, temperatures heat up into the upper 80s and lower 90s and forecast soundings predict instability of 2500-3500J/kg with little or no CIN and very steep lapse rates. The environment will be primed, it will just need something to get storms going. As discussed, we don't have real strong signals until Thursday night when there is lift with the shortwave trough breaking down the ridge with a cold front. This afternoon, weak lift does move into the region and the CAMS increase thunderstorm chances in eastern Kansas. The NAM is dry locally, however several of the other models indicate isolated storms possible this afternoon in southeast Nebraska and southwest Iowa. Tonight some of the storms over central Nebraska may make it into northeast Nebraska. Thursday there is stronger warm air thus spotty storms continue. Thursday night, the coverage increases with the shortwave trough passage and some of the storms in Iowa could linger Friday morning. The precipitable water values are around and inch and these increase to 1.5 inches by thursday morning and continue Friday. These high pwats combined with storms motions of 10 to 20kts mean that locally heavy rain will be possible. Related to severe weather, the instability is moderate, however the shear is on the weaker side. Locally heavy rain and marginal severe hail seem to be the biggest risks. Even though it will be warmer and more muggy, a south breeze each day should help. .LONG TERM...(Friday night through Tuesday) Issued at 230 AM CDT Wed May 23 2018 The extended forecast Saturday through Monday still looks mainly dry with above normal temperatures in the upper 80s to lower 90s. A storm system will be over parts of California and Nevada and affecting the Gulf and Atlantic coasts and we are in-between. That being said, with moisture in place, heating and a weak cap or no cap at times, it would not be unreasonable to see a few storms over the weekend. && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) Issued at 1210 PM CDT Wed May 23 2018 VFR conditions through the period. Gusty south southeast winds 12 to 21 knots this afternoon, with gusts diminishing by 00-02z. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ UPDATE...DeWald SHORT TERM...Zapotocny LONG TERM...Zapotocny AVIATION...DeWald
Office: GID FXUS63 KGID 231114 AFDGID Area Forecast Discussion National Weather Service Hastings NE 614 AM CDT Wed May 23 2018 .SHORT TERM...(Today and tonight) Issued at 249 AM CDT Wed May 23 2018 Warm air has arrived in southwest flow aloft across the Central Plains while an closed upper low pressure system lifts through the northern Rockies today. Southerly low level flow will be on the increase in a tightening pressure gradient as surface low pressure deepens along the high plains, with south wind speeds ramping up to 15-25 mph with gusts around 30 mph. Temperatures will be very similar to yesterday with highs well into the 80s to around 90 degrees. Thunderstorm chances today are not overly favorable and the SPC marginal severe weather risk has shifted west, just clipping our western zones. The instability axis is primarily oriented across western Neb/KS and west of Hwy 281 in our area. Short term models suggest the potential for a storm or two to develop west of Hwy 281 mid/to late afternoon or early evening, then convection focuses to our west along the high plains in the vicinity of the surface low while a shortwave lifts out of the Rockies. The western convection may edge towards our western zones late tonight, with an overall expected weakening trend. .LONG TERM...(Thursday through Tuesday) Issued at 249 AM CDT Wed May 23 2018 On Thursday, thunderstorm chances are trending up for the evening/night while the upper waves lifts to the Northern Plains and the attendant trough crosses the Central Plains. The dry line mixing eastward, focusing showers and thunderstorms and bringing the potential for strong/severe storms due to an unstable atmosphere with CAPES around 2500 j/kg and effective shear near 30kts. Hail/wind will be the primary storm hazards. The convection looks to wind down by Friday with only minimal chances for storms in northwest flow before upper ridging builds onto the plains Memorial Day weekend with dry/hot weather expected with highs in the low 90s. Thunderstorm chances return Sunday night as the ridge axis migrates east and flow transitions southwest again as another upstream upper low reaches the central Rockies. Memorial Day could see some showers/storms around, but the better precip chances look to hold off til Monday night or Tuesday as the western system begins to fill and lift out. && .AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Thursday) Issued at 610 AM CDT Wed May 23 2018 VFR is forecast through the period. Added some LLWS for EAR tonight as the LLJ looks to be stronger out west. Low probs for TS this afternoon and evening so did not put a mention in the TAFS at this time. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...Fay LONG TERM...Fay AVIATION...Beda