Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 282022

Area Forecast Discussion
National Weather Service Hastings NE
322 PM CDT Fri Oct 28 2016

.SHORT TERM...(This evening through Saturday daytime)
Issued at 322 PM CDT Fri Oct 28 2016

Overall, this continues to look like a rather quiet 24 hours as we
see a transition from a much-above normal temperature regime today
to a slightly cooler (but still above normal) one Saturday in the
wake of a passing cold front. While the official forecast remains
a dry one (meaning rain chances/PoPs are less than 15 percent),
chances may not truly be "zero" during the day Saturday especially
in our far northern counties where a few models hint at passing
sprinkles/brief light showers. Something later shifts will want to
take a look at just in case.

Taking a look at the current/recent scene as of 1930z/230 PM, as
outlined in the "update" discussion earlier today, the biggest
deviation from overnight forecast expectations have been the
fairly-plentiful high cirrus clouds streaming overhead. Although
not a solid overcast by any means, this has greatly filtered full
sunshine potential and resulted in more in the way of partly
cloudy skies than truly sunny. Even with the high clouds though,
temps have climbed pretty efficiently as of this writing, ranging
anywhere from mid-70s to low 80s so far (and even 84 at
Lexington). Will wait until after 3 PM to make final tweaks to
highs for today, but most areas will probably fall at least a few
degrees short of early morning expectations, with most places
likely topping out somewhere in the 79-84 range. In the mid- upper
levels, water vapor satellite and short term model data confirm
broad quasi-zonal flow over the local area, as we reside near the
general interface between a southern CONUS ridge and the more
active flow/jet stream core near the Canada border. Off to the
west, a low-amplitude shortwave trough is tracking through the
Intermountain West. At the surface, a broad pre-frontal trough
continues tracking east across the CWA, with gusty south-southwest
winds ahead of it gradually decreasing in speed and turning more
westerly as it passes. As outlined in previous discussions, this
trough axis has "saved" us from near-critical fire weather issues
this afternoon, as the lower RH values near/below 25 percent in
the west are not juxtaposed with the higher wind speeds in the
east/southeast counties. The "true" cold front remains off the
north over SD at this time.

Now looking ahead forecast wise through tonight and Saturday...

This evening/tonight:
For those with evening activities, it just doesn`t get much more
pleasant for late October. This evening, breezes in most of the
CWA should be down at/below 10 MPH, although some slightly
stronger speeds up around 15 MPH will likely stick around much of
the night in far southeast zones (especially around Mitchell
County KS) where the pressure gradient will remain a bit tighter.
Late tonight, the leading edges of a cold front will start
invading our northern zones, turning light breezes more out of the
east-northeast. Although it`s not completely out of the question
that some localized patchy fog could try developing toward sunrise
in the very light wind axis just ahead of this front, especially
in the far northeast CWA, the likelihood of this looks low enough
to leave out of the official fcst. Sky-cover wise, the night will
continue to feature partly cloudy skies due to continued plentiful
thin high cirrus, although this high level cloud cover is usually
less noticeable at night than it is during the day. Low temps are
a little tricky as the light winds argue for a decent drop while
the high clouds argue for holding things a bit warmer. In the end,
stuck pretty close to previous forecast, aiming for a modest
gradient from mid-upper 40s far northwest, low 50s central and
upper 50s/near 60 far southeast. During the night, the
aforementioned western disturbance will reach the CO/WY area.

Saturday daytime:
As mentioned in the opener, not as warm as today (although
probably pretty close in KS zones), but the vast majority of the
CWA should stay dry. In the mid-upper levels, the Central Rockies
shortwave trough will slide eastward into the Central/Northern
Plains states as the day wears on. However, the main zone of
lift/mid level saturation should focus 100+ miles north of our
northern CWA, focusing the best chances for rain showers near the
NE/SD border area. That being said, a few higher res models
suggest that a rogue sprinkle may not be out of the question in
our far northern zones especially during the afternoon and this
will need monitored. Otherwise, at the surface, the main feature
of the day will be the invading cold front driven southward by the
upper system. Other than in northern counties, much of the CWA
should see fairly light/variable breezes in the morning, before
steadier north-northeast breezes of at least 10-15 MPH with higher
gusts overtake most all of the local area during the afternoon.
With this daytime frontal passage, we are looking at a solid 10+
degree gradient in high temps. If anything, nudged up most areas
1-3 degrees from previous, shooting for mid-upper 60s far north,
low- mid 70s central to low 80s in KS zones. However, some areas
could see highs around mid-day with slowly falling temps as the
afternoon wears on. Sky cover should generally average partly
cloudy, but likely a bit more sun in the south and probably mostly
cloudy north for at least part of the day.

.LONG TERM...(Saturday evening through Friday)
Issued at 322 PM CDT Fri Oct 28 2016

General overview of this 6-day period:
Overall, our incredibly dry and seasonably-mild stretch of mid-
fall weather continues. By far the most noticeable change from the
previous forecast package is that small rain chances were removed
from the Wednesday night-Thursday time frame. As a result, the
official forecast is completely dry (at least for now). Otherwise,
the main "impactful" weather concern involves the likelihood of at
least "near-critical" fire weather issues for Monday afternoon.
See the separate "fire weather" section below for any further
discussion on this topic. Temperature-wise, we are looking at
fairly uniform/consistent daily highs in the 60s to near-70 on
most days, with the one notable exception of Monday (Halloween),
which is essentially a one-day "spike" into the upper 70s-mid 80s
range ahead of the next cold front. As for lows, although a few
nights will probably dip into the 30s (especially north and west)
we continue a remarkable stretch void of a true hard freeze.

With the basics covered, will end with some fairly brief day-to-
day details including a mention of a few caveats to the seemingly
extremely quiet forecast...

Saturday night:
The disturbance mentioned in the "short term" section above passes
to the east. Again, suppose a few sprinkles cannot be 100 percent
ruled out, but will keep it dry with any weak shower/thunderstorm
activity focusing well to the east over IA. A decent batch of low
clouds could invade from the north, and suppose some patchy fog
cannot be ruled out mainly in our far west toward sunrise in the
surface ridge axis but will leave this out for now.

Sunday/Sunday night:
Cooler than Saturday with a more uniform high temperature field
mainly in the 62-67 range. Winds fairly light/variable much of the
day but becoming more established from the south in the afternoon
and remaining steady southerly overnight. In this southerly flow,
dewpoints/low level moisture will be on the rise and a batch of
low clouds and perhaps light fog is likely. The NAM is even
suggesting some spotty drizzle a few hours either side of daybreak
Monday, but this looks a little over-done given such a shallow
moist layer.

Monday/Monday night:
Clearly the warmest day of the long term periods. Possibly a very
cloudy/gloomy start but sun should break out in full force during
the afternoon as surface winds increase/turn westerly, with gusts
of 20-30 MPH likely in western zones but lighter east. High temps
well into 70s in Nebraska with low-mid 80s more common in KS. Once
again, fire weather likely an issue, especially west.

Tuesday/Tuesday night:
High temps return back down into the upper 60s/low 70s behind the
passing front. There are some hints that some shower/weak
thunderstorm activity could flirt with especially our far
southeast zones late in the night, but confidence is still too
low for a formal mention.

Wednesday/Wed night:
The latest GFS/ECMWF are in good agreement with a shortwave trough
traversing the central CONUS, but as with recent systems our
timing for appreciable rain appears to be "off", with better
shower/storm chances focusing east and as a result rain chances
have been removed from our CWA and instead focused slightly east.
High temps aimed almost identical to Tuesday.

A generally "ridgy" mid-upper pattern returns to the local area,
as we are "split" around by the main jet energy to the north and a
small-scale upper low to the southwest. As a result, things
currently look quiet and dry with high temps mid-upper 60s.


.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Saturday afternoon)
Issued at 1228 PM CDT Fri Oct 28 2016

General overview:
Confidence remains rather high in VFR ceiling/visibility and
rain-free conditions through the period, with only fairly
appreciable high level cloud cover continuing to stream overhead
the majority of the time. As for surface winds, the strongest
southwesterly speeds of the period will occur right away this
afternoon with gust potential to around 20kt. By mid-late
afternoon, speeds will start dropping off as the pressure gradient
relaxes, and for the evening/overnight hours speeds will average
well under 10kt and trend toward variable direction. Very late in
the period toward mid-day Saturday, a steadier northeast wind will
just start becoming established behind a passing cold front, but
with the more pronounced increase in speeds holding off until just
barely after this valid period, will defer to next TAF cycle to
address this with another FM group.


Issued at 322 PM CDT Fri Oct 28 2016

Regarding Monday afternoon:
Although it`s still 3 days away and obviously subject to at least
minor adjustments, this still looks like the primary "fire weather
day" in the 7-day forecast, and it follows suit that it`s also the
warmest day. For now, will maintain a "near-critical" mention in
the Hazardous Weather Outlook (HWOGID) mainly targeting counties
west of the Highway 281 corridor, but would not be surprised to
see forecasted fire weather parameters in our eastern zones also
trend this way with time. At least for now though, the most
concentrated overlap of low-RH and gusty winds (20-30 MPH gusts)
looks to be in our western half. Cannot rule out especially our
far western counties eventually trending worse into "critical"
territory that might require Watch/Warning issuance, but these
headlines would likely not come out until later in the weekend at
the earliest.

Closing with a quick review of our local fire weather
definitions: "Critical" in our CWA is defined as the 3+ hour
overlap of relative humidity (RH) of 20-percent-or-lower and
sustained winds/gusts of 20+ MPH/25+ MPH. "Near-critical" is
defined as the overlap of 25 percent-or-lower RH and sustained
winds/gusts of 15+ MPH/20+ MPH (in the presence of sufficiently
dry vegetation).




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