Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 191150

Area Forecast Discussion
National Weather Service Hastings NE
650 AM CDT Wed Oct 19 2016

.SHORT TERM...(Today and tonight)
Issued at 459 AM CDT Wed Oct 19 2016

For not being "high impact" weather, these next 24 hours are
deceptively tricky, especially with trying to pin down/refine the
very short term details regarding rain chances. While nearly
everybody stands at least "some" chance of a little rain by
sunrise Thursday, the exact likelihood of it falling at any given
location, along with exact timing and amount carry below-average
confidence. As a result of this uncertainty, the official forecast
keeps official rain chances (PoPs) at pretty low percentages
(20-30 percent tops) at any given location, but there is little
doubt that parts of the CWA will almost certainly see some rain,
so these low PoPs are a bit deceiving from a larger-scale
viewpoint. The main points to emphasize are probably 1) It
certainly won`t rain for hours straight anywhere...for some
places it might just be one or two brief showers while others may
barely even catch a sprinkle 2) Because of this, actual rain
amounts over the next 24 hours are unlikely to average more than a
few hundredths of an inch in most areas, if even that, but as
always, a few isolated spots will almost surely see a bit more.
Before moving on to the main meteorological discussion, want to
also mention that thunderstorms have been kept out of the official
forecast (and Hazardous Weather Outlook), as instability levels
appear to be quite meager overall. That being said, the risk of a
few isolated lightning strikes/rumbles of thunder is not
necessarily "zero" either, so this is something upcoming shifts
may have to consider inserting on short notice if a few weak/non-
severe storms do in fact show their hand.

Turning to the current scene as of 09z/4AM:
So far, the night/early morning shaking out pretty much as
expected 24 hours ago. In the big picture of the mid-upper levels,
water vapor imagery and short term models confirm seasonably-
strong west-southwest flow aloft over the Central Plains, as a low
amplitude/progressive shortwave trough continues approaching the
local area from its current position roughly centered over the WY/CO/NE
border area. At the surface, a very light/variable wind regime
remains in place locally thanks to broad high pressure. As was
expected, the vast majority of the CWA has remained dry overnight
despite a considerable amount of mid level cloud cover mainly over
the northwest half of the CWA, while southern areas have averaged
clearer. However, radar trends and a few airport obs suggested
that parts of our far north (mainly Valley/Greeley counties) may
have seen a brief sprinkle earlier in the night. Steadier light
rain though has clearly been focused over the northwest Nebraska
area. Also as suspected as a possibility 24 hours ago, the
variable cloud cover across the CWA has resulted in some tricky
temp trends, with cloudier northern areas steadying out or even
rising a bit during the night (most of these areas currently in
the upper 40s/lower 50s) while clearer southern areas have
continued to drop (mainly in the mid 40s at this time). See no
reason why these temp trends won`t continue through daybreak.

Now looking ahead forecast-wise through roughly sunrise

Early this morning through roughly sunset today:
Obviously the opening paragraph highlights the challenges in
messaging this forecast, as it`s tempting to completely downplay
rain chances altogether, but there is just enough forcing that at
least a few rogue sprinkles cannot be ruled out almost anywhere.
In the mid-upper levels, the aforementioned disturbance will
continue shifting east into the local area as the day goes on.
However, several deterministic models such as the latest
NAM/GFS/RAP suggest that except for maybe the far northern/west-
central fringes of the CWA, rain chances during the daylight hours
could be extremely minimal. This is due in part to the currently
halfway-organized zone of mid level saturation/frontogenesis over
the Sandhills falling apart/disorganizing as it shift
east/southeast today. That being said, higher res solutions from
models such as the NSSL WRF and 4km WRFs suggest that there
could be just enough forcing/cooling aloft along with meager
instability to possibly pop some "random" showers/sprinkles almost
anywhere in the CWA, especially in southern zones. As a result,
have at least introduced a "slight chance of sprinkles" this
afternoon to those areas that previously carried no mention of
rain whatsoever. At the surface, the passing wave will drive a
weak cold front southward across the CWA during the day, promoting
slightly breezy north-northwest winds of at least 10-15 MPH for
much of the day and higher gusts possible (this reflects a slight
increase from previous forecast). Temp-wise, made very little
change from previous, aiming for a modest range from upper 50s far
north (where it should average cloudiest) to upper 60s south
(where much of the day should be partly cloudy at worst).

This evening/tonight:
In theory, the night hours will probably feature a slightly
better (but still small PoP-wise) chance of passing showers than
the daytime will. Like the day though, there is enough variability
between various model solutions that it`s hard to really pin down
expectations, even at this short time range. In the mid-upper
levels, a secondary shortwave trough initially trailing the
leading one more or less phases together into one modestly
strengthening/amplifying disturbance over the heart of the local
area overnight. Despite scant low level moisture/instability, this
increasing forcing favors at least isolated, if not scattered
light rain showers almost anywhere within the CWA, and thus 20-30
PoPs are blanketed throughout the night. Again though, we are
likely talking very minimal rain amounts and not everybody will
even see any. In other departments, breezes through most of the
night should average only 5-10 MPH from a northerly direction.
These light but steady breezes, in combination with what should be
generally mostly cloudy skies, should preclude a significant temp
drop barring any unexpected areas of more solid clearing. Again
made very little change here from previous and stuck close to a
model blend consensus, aiming from upper 30s in most
northern/western counties and low 40s in most eastern/southern

.LONG TERM...(Thursday daytime through Tuesday)
Issued at 406 AM CDT Wed Oct 19 2016

The main weather concern is in the first half of Thursday.
The NAM and GFS hint that Lingering precipitation Thursday morning is
possible from the system today as the upper energy moves overhead
early Thursday morning. Only included a slight chance, because
confidence in how widespread this precip may be is low. Again, do
not expect much in way of accumulation. Clouds and the passage of
the weak cold front will keep Thursday temperatures slightly
cooler. Highs in the upper 50s and low 60 are expected.

Other than this system. Upper level ridging will build in and
persist through the weekend. The next upper system that may impact
the region will be Tuesday into Wednesday. Medium Range Guidance
has been struggling with this the past couple of days, so
confidence is low on how this will evolve at this time. A few weak wind
shift boundaries will move through the area for the end of the
work week and through the weekend from systems over southern
Canada. Temperatures will be above normal with highs in the 70s
through much of the period Friday - Tuesday next week. Lows will
be in the upper 30s and 40s.


.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Thursday morning)
Issued at 650 AM CDT Wed Oct 19 2016

General overview:
Despite plentiful mid-level clouds through nearly the entire
period, confidence actually remains pretty high in VFR
ceiling/visibility. There are small chances for passing rain
showers at either terminal mainly during the evening/overnight
hours and have introduced a generic "vicinity" (VCSH) to the
latter 12 hours to cover this possibility. There are some hints
that ceilings could try lowering closer to MVFR levels especially
during the final 3 hours or so of the period, but this is far
enough out in time was not willing to go this pessimistic yet. As
for surface winds, the majority of the period looks to feature a
northerly breeze at/below 10kt. However, a steadier north-
northeast breeze around 12kt with higher gusts is likely
especially in the 18-23z time frame this afternoon.




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