Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 272351
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
651 PM CDT Tue Jun 27 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 356 PM CDT Tue Jun 27 2017

Upper level flow has become more progressive as a mid to upper
perturbation heads toward our area tonight. Storms should develop
along a trough, ahead of a cold front, in the lee of the Rocky
Mountains this afternoon as heights lower.

A stubborn area of clouds in our southwest is slowly advancing
northeastward near a warm front. Expect the warm front to continue
moving northeast and be through most of the CWA by midnight.

The convection that develops to the west will hold quite a threat of
large hail at initialization as lapse rates will be steep to the
west. The convection is expected to eventually outrun any large
scale ascent as the convection moves east, but convection will enter
a regime of increased moisture near the surface as a cold pool will
likely enhance elevated convection. Storms should aggregate into
a squall line well before convection reaches our area. A potent
low- level jet will develop this evening that will help enhance
any ongoing convection that comes our way. So by the time
convection arrives, our main threat will transition more to wind
rather than large hail with good bulk shear, although some large
hail cannot be ruled out, especially in our west. Storm relative
helicity would indicate at least a small chance of a quick spinup
along the leading edge of the squall line.

The trailing cold front may be problematic for Wednesday as it will
probably stall just to the southeast of our CWA, and potential
will be close enough for some afternoon convection in our
southeast. As a perturbation moves in Wednesday night along with
an increasing low- level jet. The nose of the jet will likely be
somewhere in the southern CWA, but looking less likely that the
stronger low-level convergence will hang over our CWA for too
long. However, it would not be out of the question to get enough
rain to cause some localized flooding Wednesday night, and even
some severe weather along the stalled boundary that will make its
way north. I may be too low with current chances of precip for
part of the CWA as areas just north of the boundary could get a
good rain. Hard to tell where exactly this boundary will be
Wednesday night, however. Severe parameters indicate we could get
some large hail, and possibly even some wind.

Muggy conditions come back through Wednesday night with increasing
dewpoints and more typical summertime temperatures.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 356 PM CDT Tue Jun 27 2017

Lingering convection from Wednesday night is possible heading into
the morning on Thursday. With a shortwave tracking across northern
Nebraska and South Dakota during the day and low pressure
approaching from western Kansas, precipitation appears likely across
much of the area. Depending on where any residual boundaries set up,
a few strong to severe thunderstorms could be possible. Models are
hinting that this could end up being just to our south and east, but
there are also signs of lingering elevated instability behind the
front helping promote additional thunderstorm development into the
evening.

The northwest flow pattern returns Friday as the upper level trough
shifts to the east. Am generally expecting most places to remain dry
the next two days but with a couple weak waves moving through Friday
and Saturday, a few scattered showers and thunderstorms are possible
so have kept some low pops across portions of the area both days.

Surface winds become southerly heading into Sunday drawing up warm
humid air back into the central plains. Models are suggesting we
will have a decent chance for precipitation across the area Sunday
afternoon and evening as a more vigorous shortwave moves into the
area. It is still too far out to narrow down specifics on timing and
severity, but will continue to monitor this for any possible MCS
development.

Models begin to diverge on how fast this shortwave exits the area on
Monday lowering confidence on precip chances. The ECMWF is a bit
slower with things and has QPF across our northern counties, while
the GFS is much faster and has it exiting the region leaving things
mainly dry.

Although temps the next 7 days look quite seasonal with highs in the
80s and low 90s, looking a few more days out, the Climate Prediction
Center has our northeastern zones outlooked for excessive heat July
6th and 7th as an upper level ridge is expected to build in
across the area. This will be something to keep an eye on as it
approaches.

&&

.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 626 PM CDT Tue Jun 27 2017

A large cluster of thunderstorms is forming to the west of the
terminals and is expected to continue to expand in coverage as it
approaches the local area over the next several hours. Doing a
very simple timing of this cluster...it looks like it should begin
affecting KEAR by 28/02Z...and maybe KGRI an hour or less
afterwards. While CIGS will remain high and likely in VFR
categories...depending on the intensity of the rain...could
briefly see MVFR VSBYS or less. While VSBYS are somewhat in
question...of more certainty are the strong winds that should
accompany these storms...and introduced a variable wind group to
45 KTS at both terminals with this activity. Once the MCS tracks
east overnight...expect clearing skies and LLWS to develop at both
sites. Winds will eventually relax out of the west around
daybreak...with mostly sunny skies anticipated through the daytime
hours.

&&

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

$$

SHORT TERM...Heinlein
LONG TERM...Petr
AVIATION...Rossi


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