Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 181159

Area Forecast Discussion
National Weather Service Hastings NE
659 AM CDT Wed Apr 18 2018

.SHORT TERM...(Today and tonight)
Issued at 410 AM CDT Wed Apr 18 2018

A few light showers...sprinkles or even flurries will be possible
over the next few hours as the responsible area of low pressure
continues to slowly push east of the local area. At the same
time...the pressure gradient will remain fairly tight across the
local area on the backside of this low...and the breezy
conditions we are experiencing this morning should only pick up
and become more windy as we approach late morning. With plenty of
cloud cover lingering across the local area along with these stiff
breezes...this will not make for the most pleasant day across the
local area.

With more cloud cover now forecast through the afternoon
hours...did ratchet down forecast high temperatures a couple of
degrees. Even so...temperatures across north central Kansas should
climb to near 60...resulting in RH values falling to near or below
30 percent this afternoon. While this is very marginal...winds
will be on the stronger side...and felt it was a good idea to
continue to mention fire weather concerns in the HWO given the
very breezy/winds conditions that will accompany the marginal RH
values along with the very dry antecedent conditions across north
central Kansas.

Winds will then begin to decrease late in the day as surface high
pressure sinks down across central Nebraska from the north. With
these light winds...clearing skies and falling temps...could
potentially see some patch fog formation across our north per SREF
guidance...but largely ignored this for now as confidence in cloud
cover late this afternoon through evening is on the lower end of
the spectrum. Either way...overnight lows should drop to very
near or below freezing given the cold airmass and light
winds...which is still about 10 degrees below seasonal norms.

.LONG TERM...(Thursday through Tuesday)
Issued at 410 AM CDT Wed Apr 18 2018

General overview of this 6-day period:
Overall, very little change will be noted with this forecast package
versus recent ones of the past 12-24 hours. Although the weather
pattern is not truly quiet, it`s worth noting that for probably the
first time in at least two weeks, we have no forecasted weather
elements worthy of formal inclusion in our Hazardous Weather Outlook
(HWOGID) for the Days 2-7 period (no thunder, no snow/ice, no strong
winds, no fire weather etc.). Here are the two main stories as we
see them:

1) There are two windows of opportunity for rainfall/precipitation
during these 6 days, the first one from Fri-Sat in association with a
slow-moving/large-scale upper level low passing mainly to our
south...and the second one a more progressive shortwave trough way
out in the Mon night/Tuesday time frame. On either side of these two
precip chances, days such as Thurs/Sun/Mon continue to carry pretty
high confidence of staying dry. Focusing mainly on the first system
for Fri-Sat, and as discussed here 24 hours ago, this continues to
not look like a "major" rain-maker for our coverage area (CWA), and
it certainly will not rain non-stop through these two days despite
the various chances (PoPs) in the forecast. While the actual chances
for SOME measurable rain have changed very little in the past 24
hours, the actual expected amounts continue to trend down somewhat.
Furthermore, the orientation of the highest rain potential/amounts
has started shifting a bit, looking less like north vs. south and
more like west-southwest (wetter) versus east-northeast (drier).
Even so, our latest stab at rain totals Fri-Sat only has a general
range from 0.05-0.25" across roughly our northeast half, and more so
0.25-0.75" in our southwest half. Yes, some beneficial rain for
sure, but not as much as especially our southern counties probably
want/need. As was the case 24 hours ago, snow continues to look like
a non-issue for a change, and although it`s hard to completely rule
out a few rogue lightning strikes with these rain chances (it is the
latter half of April after all!), instability values currently
appear too meager to justify a formal thunder mention.

2) Temperatures continue to average on the cooler side of normal.
It was so cold the first half of the month that many of us have
probably gotten "out of touch" with normal/average values, which
currently means highs in the mid 60s and lows in the mid 30s to
around 40. At least in terms of high temperatures, at least 5 of
these 6 days look to top out roughly/at least 5 degrees below
normal, meaning we will see mainly highs in the 50s in Nebraska
zones, and any lower 60s most favored in KS zones. At least for now,
only one day (Monday) looks to feature actual NORMAL (to perhaps
slightly above?) highs in the mid-upper 60s, but this is still 6
days away so it`s not "in the bag" yet by any means. As for low
temps, for the first time this spring, we look to put together a
pretty solid string of at least slightly ABOVE- freezing nights
(starting Thurs night). Re-stating what was written here last night,
we still deem it a bit too soon for formal Frost/Freeze headlines,
but these could start coming into play if-needed as we get closer
to/into early May, now that vegetation should start growing a bit
more aggressively without frequent sub-freezing temps to contend

With the main two stories covered, will finish up with some fairly
basic day-to-day specifics...

Thursday/Thursday night: While confidence always was high in a dry
day, the entire CWA is now also void of any precip chances Thurs
night as well, as the majority of models keep any activity at least
slightly off to our west or south through sunrise Friday. In the mid-
upper levels, a brief period of shortwave ridging passes overhead,
while at the surface, the wind regime strongly resembles that of two
days ago (Monday), with light morning breezes generally northerly in
the presence of surface high pressure, then turning more east-
southeasterly at 10-15 MPH (higher gusts west) during the afternoon.
Starting right away early Thurs AM, some models/guidance suggest
that especially some of our northern counties could at least patchy
fog potential. Although this cannot be completely ruled out,
especially given the moist ground from our departing light precip
event, have coordinated with the short term forecaster handling the
Wed night period to forego a formal mention for now and let the next
few shifts take a closer look. Even if the morning does start with
some fog in spots, most of the day should feature plenty of sun.
High temps were changed little, ranging from low-mid 50s north to
low 60s south. Thurs night, breezes will continue averaging 5-15 MPH
from the east-southeast, and low temps should hold just at to
slightly above freezing, with most areas aimed 31-36.

Friday daytime-Saturday evening: See #1 above for more details on
rainfall expectations. In the big picture of the mid-upper levels,
both the ECMWF/GFS have come into slightly better agreement on the
eventual track of the primary mid level low, tracking it out of the
central/southern Rockies Friday, and generally along the KS/OK
border area (mainly favoring OK) on Saturday. If anything, the ECMWF
may have nudged north a bit since 24 hours ago, but still far enough
south that the heaviest/steadiest rain should still focus to our
south. Again, the basic message is that while nearly the entire CWA
should see at least a LITTLE rain at some point Fri-Sat, our
southwest half is most favored for somewhat more. As for the timing
of the best rain chances, it`s worth noting that Friday daytime
keeps trending drier (in fact the latest NAM is dry CWA-wide), so
the overall- highest PoPs are focused Fri night-Saturday daytime
before precip largely departs by midnight Saturday night. Likely
very related to the slower onset of precip, high temps Friday were
nudged up a few degrees, with upper 50s to near 60 most areas, and
then a bit cooler Saturday with more clouds/rain potential.

Sunday daytime-Monday daytime: These two days remain dry in the
forecast, as at least low-amplitude shortwave ridging should prevail
in the wake of the departing upper low that gradually departs into
the southeast CONUS. While not truly warm by April standards by any
means, these currently appear to be the warmest two days of the
current 7-day forecast, with highs climbing from the low 60s Sunday
to mid-upper 60s Monday.

Monday night-Tuesday: Right at the Day 7 range, the next possible
precipitation chance enters the picture as the southern portion of a
shortwave trough centered over Canada brushes by. Although
confidence in the details is obviously very low this far out, like
the Fri-Sat precip chances, this looks like mainly a cool rain and
little more. Timing-wise, PoPs are in the forecast for both Mon
night and Tues daytime, but as is often the case, the GFS is faster
bringing in rain chances Mon night, while the ECWMF favors Tuesday
daytime. Tons of time left to sort out the finer points of this


.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Thursday)
Issued at 630 AM CDT Wed Apr 18 2018

Low level stratus continues to wrap around the departing low
pressure system bringing MVFR CIGS to both terminals. Expect CIGS
to slowly improve from west to east later in the day...but for
some mid level clouds to persist through at least the late
afternoon through early evening hours. Winds...however...will be
the focus...with increasing winds throughout the morning hours as
the pressure gradient remains strong on the backside of the
departing system. Late in the day...winds should begin to decrease
to around 10 KTS or lower after dark as an area of surface high
pressure sinks south across the local area.




LONG TERM...Pfannkuch
AVIATION...Rossi is the U.S. government's official web portal to all federal, state and local government web resources and services.