Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 170524
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
1224 AM CDT Tue Oct 17 2017

.SHORT TERM...(This evening through Tuesday Night)
Issued at 328 PM CDT Mon Oct 16 2017

Upper level flow remains northwesterly across the region today,
set up between broad high pressure extending north from the
western US/Mexico border and a trough axis sliding toward the East
Coast. A weak shortwave disturbance continues to slide in from
the northwest, but outside of a few clouds (also accompanying an
upper level jet streak) in our mostly clear skies, there hasn`t
been a notable impact. At the surface, gusty southwesterly winds
remain in place, thanks to a tightened pressure gradient between a
trough over western NE/KS and high pressure to our SSE and mixing
into some stronger winds aloft. Sustained speeds have generally
been in the 15 to 20 MPH range, with gusts mostly 20-25 MPH, but
there has been an occasional gust over 30 MPH. Good call by mid
shift expanding the mention of near critical fire weather
conditions, as all automated sites have RH values in the 17-27% at
3 pm. For the few sites closest to both critical wind and RH
criteria, will be close whether or not they hit the 3 hrs needed.
At this point, will hold off on any headlines and keep the mention
going in the HWO.

Dry conditions remain in the forecast tonight through tomorrow
night. Models are in good agreement showing the upper level flow
continuing to be northwesterly, and while another disturbance
looks to push through Tues evening/night, similar to today there`s
a lack of moisture to work with. At the surface, that trough axis
currently sitting off to our west gets pushed further east
tonight, but stalls/weakens as its upper level push moves away.
This will bring diminishing winds, turning more northwesterly with
time, with many areas likely light/variable late tonight and into
part of tomorrow. As we get through the afternoon hours tomorrow
and into tomorrow night, southerly winds look to return as another
trough axis develops over the High Plains. Speeds will be notably
lower than they have been this afternoon. Made little change to
forecast highs for tomorrow, with mid 70s expected CWA-wide. It`ll
be a really nice day.

.LONG TERM...(Wednesday through Monday)
Issued at 328 PM CDT Mon Oct 16 2017

At 12Z Wednesday, models are in good agreement showing more zonal
flow in place in the upper levels, thanks to an area of low
pressure sliding east across central Canada. Again, no
precipitation is expected, but this system will push a front
southward through the region. Timing between models isn`t bad, by
around midday Wednesday the front is 1/3-1/2 way through the CWA,
pushing just outside of the SE corner of the CWA during the early
evening hours. It will bring a switch in winds to the NNW, though
it`s not a strong push, so winds don`t look to be strong. As far
as temperatures go, with the timing of the frontal passage being
during the afternoon, though temps aloft may be a touch cooler,
increased mixing ahead of it looks to keep temps in the mid-upper
70s.

Models show shortwave ridging developing for Wed night and
Thursday, keeping the dry forecast intact. The ridge axis passes
through the CWA before becoming more amplified, as a shortwave
disturbance is crossing the four corners region, turning upper
level flow south- southwesterly through the afternoon. Also kept
the forecast dry for Friday, though late in the day (and more into
the evening hours), more uncertainty arises, as lift starts to
increase between the above mentioned disturbance as well as energy
moving out of the Pac NW. Southerly winds start picking up some
on Thursday, but Friday is currently looking like the windier day.
Pressure gradient tightens up across the region thanks to
deepening low pressure along the High Plains, and sustained speeds
of 20-25 MPH will be possible. Highs both Thursday and Friday
look to top out in the mid 70s.

Friday night into Saturday, while there are some slight timing
differences, model agreement is pretty good showing this being the
time frame the system swings through. Thunderstorms are expected
to develop as the trough axis/surface cold front swings through,
and with models showing instability being pushed east of the CWA
by around midday, decided to remove thunder mention from 18-00Z
Sat. We`ll see if the models keep that trend. Once this all swings
through, the dry forecast returns for Sun-Mon. Highs for Saturday
are tricky due to the timing of the front/precip chances, but Sun
is currently forecast to top out in the mid 60s, with mid 60s-
lower 70s for Mon.

&&

.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Wednesday)
Issued at 1224 AM CDT Tue Oct 17 2017

General overview:
Extremely "quiet" aviation weather on tap...extremely high
confidence in VFR ceiling/visibility, zero chance of precip and
only limited high level cloud cover at times. Unlike during the
preceding 24 hours, sustained windspeeds look to remain near-to-
below 10kt the entire time, with a southerly direction prevailing
the majority of the time.

Low level wind shear (LLWS) these first few hours:
About the only real issue to speak of is 1-2 hours of lingering
LLWS right away early this morning, as southwesterly winds roughly
35-40kt within the lowest 1000 ft are resulting in roughly 30kt of
overall shear magnitude between the surface and this level.
Already by 08Z (perhaps 07Z at KEAR), this corridor of stronger
low level winds will have departed off to the southeast, allowing
LLWS to drop below mentionable thresholds.

&&

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

$$

SHORT TERM...ADP
LONG TERM...ADP
AVIATION...Pfannkuch



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