Area Forecast Discussion
Issued by NWS Hastings, NE

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669
FXUS63 KGID 261044
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
444 AM CST Sun Feb 26 2017

.SHORT TERM...(Today and tonight)
Issued at 417 AM CST Sun Feb 26 2017

Main forecast challenge will be temperatures today and potential for
fog tonight.

Stuck some brief chance of flurries this morning in the pre-first
period over parts of Osborne and Mitchell Counties as some radar
returns near there are showing up. Model soundings indicate that we
are quite dry in lower levels, so most of any precip will be virga.
The lift will be brief as the subtle wave largely responsible
scuttles quickly east. Any mid-high level cloudiness early this
morning should move off quickly as subsidence takes over, giving us
a sunny day. Wind should be light, so the forecast relative humidity
of less than 25 percent in our southwest should not be a huge worry,
as long as the wind stays light. Superblend temperatures were too
cold and I suspect that the input included too much influence of
snow on the ground. Much of the snow already melted yesterday, and
judging by highs yesterday and with plenty of sunshine today, most
locations should have no problem making at least 40s for highs.

For tonight, the development of fog/stratus looked like it could be
an issue with increased moisture return, but the SREF and other
models seem to be backing off, with fog/stratus remaining
east/southeast of the CWA tonight with lows near 20 to the mid
20s, with the exception of Ord, where cold air should sink into
the valley and I expect a low closer to 12 in Ord. Still looks dry
for tonight.

.LONG TERM...(Monday daytime through Saturday)
Issued at 444 AM CST Sun Feb 26 2017

General overview of this 6-day period:
All things considered, little in the way of noticeable change is
evident in this forecast package versus the previous one 12 hours
ago. Very basically, this means that the majority of pesky forecast
"issues" (some of which may or not be much of an issue at all) are
still expected to focus during the Monday-Tuesday night time
frame, with a dry forecast and seemingly more-straightforward
weather then taking over Wednesday into the weekend.

Precipitation-wise (also fog potential):
There are still a few opportunities for what should (for the most
part) be light/pesky precip chances during the Monday-Tuesday
night time frame. Unfortunately, like 24 hours ago, there remain
some issues with precip type, and although the overall chances do
not appear as good as they previously did, have maintained a low-
confidence mention for a light wintry mix (freezing rain/maybe
sleet) for far northern counties late Monday night, which was
introduced by previous day shift. Overall though, the "main"
opportunity for measurable precipitation (probably favoring snow
as predominant type) still looks to focus Tuesday night, with the
best chances favoring our KS zones with lesser chances northward
into Neb. That being said, our official snow accumulation forecast
still calls for little-to-no accumulation, and admittedly this may
need beefed up at least a touch over the next few days especially
if some recent runs of the NAM/GFS are onto anything depicting a
narrow, quick-hitting band of at least 1" possible. Fortunately,
there is still ample time to make necessary adjustments here. From
Wednesday onward, confidence in the going dry forecast remains
rather high, although suppose there could be a non-zero chance for
a rogue flurry/sprinkle here or there. As for fog potential, the
SREF/NAM plan-view visibility progs along with 00z MET numerical
guidance continues to suggest that at least "some" fog could
materialize Monday night into Tuesday morning, and with this
possibility now within 48 hours felt it would be prudent to at
least introduce a generic "patchy fog" mention to the majority of
the CWA.

Temperature-wise:
Very little change was made here to any of these 6 days/nights.
This means that especially Monday-Thursday are expected to average
near to only slightly above late-February normals, with highs
mainly somewhere in the 40s in Neb zones and low-mid 50s more
common in KS zones, with overnight lows mainly in the 20s except
for slightly milder readings mainly in the 30s right away Monday
night. Then by time we get to Friday-Saturday, a nice little
warming trend is still evident, with highs aimed into the low-mid
50s for most of the CWA Friday and then 60s on Saturday (perhaps
pushing 70 in far southwestern counties).

Potential for fire weather issues:
Despite the fact that the ground is still rather damp across much
of the CWA (and even partially snow-covered north), it won`t take
more than a few decent days of drying/breeziness to quickly dry
out grasses and potentially bring fire weather issues back into
play. Fortunately, at least for now, there are no afternoons that
look particularly-favorable for breaching critical fire weather
parameters that might require headline issuance. That being said,
especially the southern/southwestern 1/4 or so of the CWA still
appears likely to meet "near-critical" combinations of wind/low RH
on one or more days especially between Wednesday-Saturday. With
this time frame still being out in the Days 4-7 range, will forego
any mention of fire weather for now in the Hazardous Weather
Outlook (HWOGID) until things get a little closer/confidence
increases, but it will be something to keep an eye on.

With all the main points of the long-term forecast covered, will
finish up as usual with more in the way of day-to-day details...

Monday daytime:
While the official forecast is again void of any rain mention
CWA-wide (and this should hold true for at least the vast majority
of the area), the latest models suggest that the next few shifts
may need to consider adding at least a light drizzle/sprinkle
mention to especially the far southeastern fringes of the CWA
during the afternoon. Even if it does stay dry area-wide, cloud
cover should generally be on the increase as a series of low-
amplitude disturbances take aim on the Central Plains in
strengthening west-southwest flow aloft, downstream from a
larger-scale trough slowly approaching from the western states. At
the surface, sustained breezes will top out around 15 MPH from
the south as a lee trough develops to our west, allowing slightly
higher moisture/dewpoint in the 30s to advect northward. Temps are
a bit tricky, as it will be a battle between low-level warm air
advection versus increasing clouds, some of which could be lower
stratus. The going forecast is a decent middle ground of the
possibilities, aiming highs from mid-40s north to mid 50s-south.

Monday night:
Like the day, the majority of the CWA should stay dry, and the
official forecast reflects this. However, some models (including
NAM/ECMWF) are still hinting that especially our far northern
zones could see a period of light precip mainly between midnight-
sunrise. Preceding shift opted to introduce a low-confidence
mention of a light wintry mix to this northern area that could
range anywhere from rain, freezing rain or perhaps even light
sleet/snow based on low-level thermal profiles, and will keep
this going for now. However, model trends seem to be trending
downward with measurable precip potential with this disturbance,
and would not be surprised to see later forecasts trend more
toward light drizzle than anything. As mentioned above, although
not a sure thing, there seems to be enough evidence for at least
light fog development in the light southerly flow to justify the
introduction of "patchy fog" to the forecast for most of the CWA
through most of the night, with any fog in theory starting to
scour out from west-to-east toward sunrise as stronger west-
northwest breezes arrive behind a passing weak cold front. Low
temps were nudged up 1-3 degrees from previous, and perhaps not
enough, as plentiful clouds/southerly flow should keep most areas
into the 30s with any 20s most favored in far northern/western
counties such as Valley/Dawson.

Tuesday daytime-night:
Much the same theme as the preceding 24 hours, as while the
majority of the CWA probably stays dry, there are still some
halfway decent chances for a quick hit of rain/snow but this time
mainly favoring southern zones. Focusing first on the daytime
hours, lingered a patchy fog mention into the first part of the
morning mainly eastern half of the CWA, with the expectation that
any reduced visibility will steadily improve as northerly breezes
of at least 10-15 MPH arrive behind the aforementioned weak
front. High temps are expected to be similar to Monday (40s
north/50s south). By late afternoon, some models are suggesting
that light precip could begin breaking out in southern zones, and
while the default model blend tried to outright-remove small rain
chances previously introduced to our far southern zones in KS,
opted to at least maintain a sprinkle mention here. By the
evening/overnight hours, mid-upper forcing increases as the
primary, large-scale trough axis enters the Central Plains. While
models are still struggling with various details here, including
how much of the CWA really stands to see measurable precip, most
are consistently focusing the highest chances across our KS zones
with lower chances the farther north one goes into Nebraska, and
our forecasted PoPs reflect this. As earlier mentioned, some
models suggest our southern zones could see a quick burst of at
least light measurable snow, likely in a narrow band, and thus our
snow accumulation grids may need some fine-tuning.

Wednesday daytime-Thursday:
Confidence in the going dry forecast is fairly high, as all
primary models shift the trough axis east and out of our region
with time, with the mid-upper air pattern transitioning to
northwesterly. Probably cannot rule out some brief passing
sprinkles/flurries, but nothing that carries enough confidence to
"ruin" the dry forecast yet. At least for now, Wednesday looks
like the overall-windiest day of the week behind the departing
wave, and expect sustained northwest speeds at least 20-25 MPH
with gusts 30+ MPH much of the day. Temps look to be roughly 5
degrees cooler than Tuesday most areas (low-mid 40s most areas),
which should help keep RH levels down and keep the fire weather
threat from getting too out of hand despite the healthy breezes.
Thursday looks similar to Wednesday, but perhaps not quite as
windy and with temps a little warmer with 50s back into southern
zones.

Friday-Saturday:
Despite hints of a moisture-starved little wave passing through,
the forecast remains dry as the predominant mid-upper level
pattern transitions from northwesterly to more zonal. The bigger
story lies in the lower levels, where fairly strong warm air
advection is anticipated as surface winds turn
southerly/southwesterly. As a result, high temps are expected to
reach the 50s most areas Friday and 60s most areas Saturday
(pushing 70 far southwest). Unfortunately, while the details of
wind speeds/RH levels are still a little murky at this Day 6-7
range, both of these days may ultimately end up having at least
"near-critical" fire weather issues.

&&

.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Sunday night)
Issued at 1151 PM CST Sat Feb 25 2017

VFR conditions are expected. Low-level wind shear should keep
east.

&&

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

$$

SHORT TERM...Heinlein
LONG TERM...Pfannkuch
AVIATION...Heinlein



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