Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 241124
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
624 AM CDT Sun Jun 24 2018

...Sct Tstms thru Tonight Some of Which Could be Svr then Dryness
and Heat Returns thru the End of the Month...

.SHORT TERM...(Today and tonight)
Issued at 343 AM CDT Sun Jun 24 2018

Aloft: Split flow was over N America with a broad trof over the
CONUS between the two branches of the Westerlies. RAP analyses and
00Z RAOBs showed a low over WY with a 70-80 kt jet streak
wrapping around its Srn side. The NAM suggests mesoscale jet
streak was forming over Neb/IA in response to the KS/OK MCS. The
RRQ/LFQ of these jet streaks appear to be coupled over the rgn
today.

The low will slowly move into the Neb Panhandle by 00Z and then
take all the way until Tue AM to inch E along the SD/Neb border.

Surface: A weak low was over SD with a subtle/weak cool front
extending SW thru the Sandhills to near DEN and a subtle/weak warm
front extending SE to MCI. The cool front will move into the CWA
today and slowly inch its way to near Hwy 81 by 12Z/Mon.

First thing to say is there is tremendous uncertainty in the fcst
thru today with respect to timing and location of rain and the
associated threat of svr wx.

The models did not do well depicting what happened last eve and
are not doing well with what has been going on overnight. That
gives us little to no confidence in what transpires today. It`s
really just a waiting game to see how this evolves.

Today: P-M/cldy. While it could rain at any time...much of the
CWA may end up dry most of the day. Sat imagery shows a small
conveyor belt from Wrn CO into Ern WY...a belt of isentropic
ascent. This feature should gradually migrate E into Neb/KS today
and tonight...increasing the risk of shwrs/tstms.

As for the svr risk today and tonight...we`ll just have to wait
and see. There is so much debris cloudiness from on-going tstms
and clds associated with synoptic lift as well that will be moving
in. It really depends on how much this cloudiness thins/
dissipates and how much sun occurs. This could put our high temps
in jeopardy as well.

03Z SREF MLCAPE is fcst 1500-2500 J/kg from N-S. Strong wind
fields will result in more than sufficient 0-6 km shear (40 kt).

The other issue with svr wx is discerning convective mode. Given
the strength of the forcing...lots of storms are likely to
initiate (wherever that occurs) and that should lead to numerous
merges and quick upscale growth into lines. This would favor
damaging winds.

I could be way off on this...but my current impression is that
the tstms maturing over Ern CO will slide SE into KS. Not sure if
they`ll survive during the day given that an MCS occurred over Wrn
KS already. Not much will happen over S-cntrl Neb/N-cntrl KS
today until late this afternoon and eve when tstms blow up over
the E half of the CWA (E of Hwy 281).

Unfortunately...everyone W of Hwy 281 better be prepared for
disappointment as far as rain goes. I desperately hope I`m wrong
on this. It`s sad because this is the most potent system we`ve had
move thru here in a couple months. It could end up a huge waste
because of bad timing for the W 1/2 of the CWA.

There will probably be big changes to fcst POPs later today as we
see how things evolve.


.LONG TERM...(Monday through Saturday)
Issued at 343 AM CDT Sun Jun 24 2018

Aloft: The low will cont inching along the SD/Neb border Mon and
will lift into MN/WI Tue. After wks of split flow it appears the
Westerlies will finally consolidate once again in its wake. The
global models cont to fcst a broad Wrn trof/Ern ridge to develop
by Thu and cont into early July. This will put the Cntrl Plns in
SW flow.

Surface: The cool front will exit the CWA Mon AM leaving a small
area of weak high pres over the rgn Tue. High pres will then park
itself over the W Atlc. The CWA will become divided by return flow
around this high with occasional frontal intrusions from the N. A
weak cool front will move in Wed and then lift back N as a warm
front Thu before the next front arrives Fri. This front should
stall from SW-NE across or very close to the CWA.

Precip: If you don`t get much rain with this current
system...it`s going to be a while. The fronts that move in late
week will largely be unproductive at least thru Fri due to very
warm H7 temps of 15- 17C. Some mid-lvl cooling could occur by Sat
with the approach of a shortwave trof.

In the meantime...Mon the dry slot will wrap into the CWA. There
could be a few small/isolated shwrs/tstms that develop with
daytime heating in the afternoon/eve over S-cntrl Neb. Can`t rule
out an isolated svr tstm with MLCAPE up to 1500 J/kg along Hwy 81
and 30 kt of 0-6 km shear. Then dry until a slight chance for some
very isolated tstms Fri night into Sat.

Temps: Comfortable and near normal Tue...then the heat blasts
back in Tue-Sat with widespread 90s...with even a couple low 100s
over N-cntrl KS.

&&

.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Monday)
Issued at 624 AM CDT Sun Jun 24 2018

Significant Wx: Potential for IFR tstms.

Today: Predominantly VFR for most of the day. There is a some -RA
moving in from the W. Confidence is high it will survive to impact
EAR along with a WSHFT...but GRI is less certain. Sct IFR
shwrs/tstms could develop at any time...but most likely will wait
til after 21Z. Winds from the E-SE 10 kt or less...but they could
be vrbl due to the effects of tstms or tstm remnants. Confidence:
Low

Tonight: VFR will decay to periods of IFR in +TSRA with the
highest probability at GRI. It`s too early to indicate IFR in the
TAFs due to uncertainty on when and where tstms develop. CIGs
could decay to MVFR after 09Z. NE winds become NW under 10 kt...
except near tstms. Confidence: Low

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&

$$

SHORT TERM...Kelley
LONG TERM...Kelley
AVIATION...Kelley



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