Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 171107

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

.SHORT TERM...(Today and tonight)
Issued at 420 AM CDT Tue Oct 17 2017

In the wake of a Monday that was every bit as breezy/windy as
expected (if not more so at times), we are now looking at a more
tranquil and almost "ideal" mid-October day, especially if you
enjoy solidly-above normal temps that probably will climb a few
degrees higher than yesterday most areas (mainly mid-upper 70s).
Our stretch of "guaranteed" dry weather just keeps rolling.

A quick look at recent/current weather:
As of 4AM/09Z, another very quiet night continues. In the mid-
upper levels, water vapor satellite and short term model data
depict broad northwesterly flow, with a couple of low-
amplitude/moisture starved waves noted, one over our local region
now and another one upstream over the WY/MT/ID border region.
These waves are generating nothing more than limited high clouds,
and with one batch departed off to our east-southeast we again
reside under very clear skies. At the surface, there has been a
bit more breeze than last night with steady speeds of 5-10 MPH in
many areas much of the night, although they are decreasing with
time as a very weak trough axis/front bisects our CWA from
northeast-southwest. At this time, temps are running generally
5-10 degrees warmer than 24 hours ago most places. With a few more
hours of temp drop potential, expect actual overnight lows to
bottom out in the 39-45 range for most.

As mentioned, considerably less afternoon wind and similar-to-
slightly warmer temps than yesterday are the main stories. In the
mid-upper levels, the aforementioned Northern Rockies disturbance
will approach from the northwest, but should generate nothing more
than limited high cirrus, meaning plentiful sunshine will again be
the rule. At the surface, breezes today should average near-to-below
10 MPH the entire time. This morning, direction will be rather
variable across the area as the trough axis gradually washes out,
but this afternoon a more consistent southerly direction should
take hold. Temp-wise, we have been under-shooting highs a few
degrees of late, and would not be surprised if that happens again
today. However, with this in mind did nudge up 1-2 degrees from
previous, aiming most areas 75-79 and probably tagging 80 mainly
in a few far southwestern counties.

Clear skies prevail much of the night, before at least a limited
amount of high clouds spill in from the northwest late. Compared
to the ongoing night, southerly breezes should hold up a touch
stronger, averaging at least 5-10 MPH throughout. The combo of
steady light breezes and a slightly warmer airmass should keep low
temps generally 2-4 degrees milder than this morning, and have
aimed most areas into the 42-48 range, generally cooler west and
warmer east.

.LONG TERM...(Wednesday daytime through Monday)
Issued at 420 AM CDT Tue Oct 17 2017

General overview of this 6-day period:
Overall, this forecast package is pretty similar to the last one,
albeit with lesser chances/coverage of rain Fri night-Saturday.
For most of this long term time frame though, we continue high
confidence of being dry and remaining seasonably-mild. For sure,
the majority of "excitement" and also inherent uncertainty resides
in that Friday night-Saturday daytime time frame as a potent upper
system/modestly-strong cold front enters/crosses the Central
Plains. For sure we can count on some fairly strong winds
(initially out of the south Fri-Fri night and then out of the
north-northwest Saturday), but it`s still highly uncertain whether
our particular CWA will see much in the way of rain/thunderstorm
activity. If anything, the latest models have trended drier.

The basic mid-upper air pattern through these 6 days:
While yesterdays`s 12Z runs of the primary ECMWF/GFS models
exhibited some noticeable differences mainly late in the longer
term, the latest 00Z solutions are again in pretty remarkable
agreement throughout the entire Day 2-7 range. Starting Wed-Thurs,
our region will reside under an area of broad ridging as the flow
aloft gradually turns southwesterly ahead of the primary upstream
trough just starting to approach the western CONUS. Then between
Friday daytime-Saturday night, the large-scale western trough
gradually moves toward us, amplifying/deepening as its central
axis passes overhead Saturday night. In its wake, Sunday should
feature at least brief shortwave ridging, but at least for now,
both the ECMWF/GFS show another, quick-moving disturbance diving
out of the Northern Plains across mainly IA/MO on Monday, with our
area along its southwestern fringes.

Precipitation/thunderstorm potential:
As already mentioned, the latest model blends that initialize our
long term forecasts have backed off on the likelihood/coverage of
rain chances Friday night-Saturday, and this appears reasonable.
Technically speaking, only a small part of our far
eastern/northern CWA carries any mention for Friday night now, as
even the GFS shows warm-sector convection mainly focusing to our
east and north. Then during the day Saturday, while the speed of
the invading cold front is obviously a critical factor, the latest
consensus is that this front will pass through most, potentially
all of our CWA mainly dry, before a more organized line of
convection (and probably some strong-severe thunderstorms)
blossoms generally along an axis from IA southwestward through
central KS and into the Southern Plains. For now though, we are at
least showing some limited rain chances (PoPs) mainly within the
eastern 1/4 of the CWA, as our domain could still be on the
western/northern edges of active weather, especially if timing
slows as it gets closer. Almost certainly, any rain that does
potentially fall in our area should be vacated south/east by
sunset Saturday.

Little in the way of noticeable change here, although there
continue to be a few particular periods that probably could trend
warmer (such as Friday night) and cooler (such as Saturday night).
Focusing first on highs, Wednesday-Friday are clearly the warmest
of these 6 days with relatively consistent highs mainly mid-upper
70s. Saturday is then a bit of a tricky day with the cold front
slicing through, and our latest rendition has a modest gradient
from mid 60s northwest to low 70s southeast, but this is very
dependent on frontal timing. Temperature-wise, this does not look
to be a "major" front, however, and highs Sunday-Monday still are
aimed well into the 60s. That being said, if this latest model
depiction of another cold front passing through Monday occurs,
then some downward trending may be needed here. As for low temps,
it will be a bit of roller-coaster. Wednesday night will be
coolish with mainly low 40s, but then persistent southerly flow
and increasing dewpoints/moisture will give us very mild readings
on both Thursday and Friday nights, with at least mid-upper 50s
common, and suspect as it gets closer that it could trend up more
into the low 60s especially in our southeast half. These will
likely be at least near-record warm lows both nights (although the
Saturday morning lows may not survive the entire calendar day to
become official). Behind the cold front, Saturday night will feel
more like fall with mainly upper 30s/low 40s, and this could trend
colder depending on how light winds go around sunrise Sunday. Even
so, not expecting any sub-freezing temps at this point. Sunday
night is then preliminary aimed into the 40s area-wide.

Other weather concerns worth mentioning:
- Strong winds:
Have already touched on this, but Friday and Saturday will almost
surely be the windiest days of the next week. Fully expect that
our official forecast speeds will continue trending upward, as
based on the latest models Friday will probably feature sustained
southerly speeds at least 20-25 MPH/gusts 30+ MPH, with Saturday
then featuring a similar surge of strong north-northwest winds
behind the cold front. Speeds currently aren`t strong enough to
trigger a formal mention in our Hazardous Weather Outlook, but
eventually it may trend upward enough to get there.

- Near-critical fire weather conditions:
Now that we are considering vegetation (fuels) to be dry enough to
support active fire growth through the remainder of the fall, we
only need to consider meteorological factors such as wind/relative
humidity (RH) for fire danger. While no afternoons during the next
week currently look to feature a particularly-concerning combo of
strong wind AND low RH, at least in the nearer-term, we may have
to keep an eye on mainly the northwestern 1/3 of the CWA for some
near-critical conditions Wednesday afternoon. Considered
introducing this to the Hazardous Weather Outlook, but with it
being so marginal have held off for now and will let next few
forecasts take a closer look.


.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Wednesday)
Issued at 606 AM CDT Tue Oct 17 2017

General overview:
Extremely high confidence in VFR ceiling/visibility, zero chance
of precip and only limited passing high clouds. Furthermore,
unlike during the preceding 24 hours, sustained wind speeds look
to average near-to-below 10kt the entire time, with a
light/variable regime dominating the first 6-9 hours before a
generally southerly direction becomes established thereafter.

LLWS late tonight?:
Late in the period (mainly 06Z and after), there is a chance that
low level wind shear (LLWS) could reach mentionable thresholds
(30+kt), but given it currently looks rather marginal and is still
well-beyond 12 hours, will forego inclusion for now.




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