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Area forecast discussion 
National Weather Service Hastings NE
608 PM CST Friday Feb 12 2016

Short term...(this evening through saturday)
issued at 412 PM CST Friday Feb 12 2016

Want to make this very clear up front: for these next 24 hours not
featuring any "major" weather systems...this is a tricky forecast
with regard to several elements...most notably trying to figure
out whether (or not) light freezing drizzle and/or light snow will
be any kind of issue mainly within the western and northern County Warning Area.
At this point...unfortunately the level of uncertainty is still
high enough that this could one of several directions. On one
hand...any freezing drizzle over the western County Warning Area and light snow
over the northern County Warning Area could be minimal enough/light enough that it
essentially results in no impacts. On the other hand...some models
suggest that especially parts of the western County Warning Area could see enough
freezing drizzle to make untreated roads slick...and that there
could be a "sneaky inch" or so of snow tonight in northern
areas...mainly northeast of a Loup City-Fairmont line. Not
surprisingly...the official forecast follows a "middle ground"
between the "best" and "worst" case scenarios for now...so please
stay tuned for updates/adjustments from the upcoming
evening/overnight shifts. Fortunately...confidence is running
fairly high on at least one thing: Saturday will be the outright-
coldest day of the next week...with a pronounced warming- trend
arriving thereafter (see long term section below for the details).

Starting with a quick look at the here and now as of 330pm...the
majority of the County Warning Area remains under a fairly solid blanket of low
clouds that have been around all day...but parts of the northeast
1/3 to 1/2 of the County Warning Area have seen a greater-than-expected erosion of
this low cloud deck this afternoon...resulting in at least a few
hours of partial sunshine before clouds fill back in this
evening/tonight. In the middle-upper levels...water vapor imagery and
short term model data indicate broad northwest flow aloft over the
local area with no major disturbances of note nearby...as the
Central Plains remains a dividing line between a western Continental U.S.
Ridge and an eastern Continental U.S. Trough. At the surface...despite some
partial sun for some areas this afternoon...temperatures have remained
fairly steady to slowly-falling thanks to slow-but steady cold air
advection behind a cold front that is essentially backed up
against the higher terrain of the High Plains/Front Range to our
west. Current temperatures across the County Warning Area range from middle-upper 20s
northeast to middle-upper 30s southwest. Breezes are mainly out of
the east-northeast at 7-15 miles per hour. Also of note...and as mentioned
in an update discussion a few hours ago...a narrow/transient band
of fog is likely passing through parts of the southwestern 1/2 of
the County Warning Area at this time...reducing visibility to around 1 mile or
less as it passes...but only lasting a short time in any given
area.

Now looking ahead forecast-wise...

This evening/tonight: see the opening paragraph for some insight
on the uncertainties/caveats to this forecast. In the middle-upper
levels...west-northwest flow continues...with again little in the
way of noticeable disturbances/strong forcing. However...there
will be at least subtle forcing both in the low and middle levels. In
the low-levels...the low stratus deck is expected to hang tough at
least within the western 1/3 of the County Warning Area or so...and as flow in
those lowest levels becomes more southerly/southwesterly...this
could promote a favorable regime for light freezing
drizzle...especially per the NAM solution...which may be a bit
overdone. Meanwhile...in the middle levels...a northwest-southeast
oriented band of saturation/lift is expected to develop and pass
from west-to-east over the County Warning Area during the night in response to
isentropic lift within the entrance region of an upper jet over
the Midwest states. This could bring a quick dusting to maybe a
half-inch or more of snow to mainly the northeast 1/3 of the County Warning Area
after midnight. Whether or not freezing drizzle/snow becomes much
of an issue...both of these things are least favored within the
southeast quadrant of the County Warning Area...and more favored in the west and
north. At the surface...breezes overnight will become more
southeasterly with time and average generally 10-15 miles per hour. Raised
low temperatures roughly 3 degrees from previous due to the combo of
these breezes and also fairly extensive cloud cover...aiming from
around 10 degrees far northeast to around 20 far southwest.

Saturday daytime: again the precipitation uncertainties continue...but
any accumulating snow in north/northeast zones should be largely
coming to an end sometime in the morning as the aforementioned
band of middle level saturation/lift departs slightly to the north
and east. However...with low level stratus expected to remain
abundant over most of the County Warning Area during the day and with at least
weak lift/warm-air advection into the stratus layer...models such
as the NAM remain quite aggressive on light freezing drizzle
remaining an issue through the day mainly within the northwest
half of the County Warning Area. Again...the NAM sometimes ends up being overdone
with freezing drizzle potential...so for now have kept chances
well-below "likely" 60+ percent territory...but at least a slight
chance is there and cannot be ignored. Otherwise...winds will
become a bit breezy during the day averaging 15-20 miles per hour with some
higher gusts out of the south-southeast. Despite these southerly
breezes...the cold start and what should be fairly extensive
clouds will result in one more day of below-normal cold. Made very
little change to previous forecast here...aiming for a range from
low-middle 20s northeast to low-middle 30s southwest.

Long term...(saturday night through friday)
issued at 412 PM CST Friday Feb 12 2016

Primary concern in the extended period should be
temperatures...specifically the degree of warmup as the work week
progresses.

By Saturday evening...the upper air pattern should look a bit
different from what is currently going on as the Hudson Bay low is
prognosticated to slide east...allowing the ridge over The Rockies to break
down as a short wave approaches from the Pacific northwest. By
sunset Saturday that wave should be sliding across the northern
plains with the trough axis located over eastern Montana/northeast
Wyoming. Better forcing associated with the wave should remain
north/northeast of the County Warning Area...so we should stay mainly dry overnight.
The NAM does bring the wave just far enough south to give the
northwest quarter of the County Warning Area a shot at light precipitation Sat
night...but this looks to be an outlier amongst the models.

Starting Sunday and continuing for most of the workweek a broad
upper ridge is forecast to move over the western half of the Continental U.S..
this puts the middle of the country in northwest flow early on and
we may have to deal with a clipper-type of wave or two through
Wednesday. Precipitation chances appear low but not completely out of the
question. However will keep out of the forecast for now except for a
slight chance south Sunday night.

The larger factor will be how do these waves influence temperatures.
There will be several wind shifts with the first one starting late
Saturday night as winds turn from south to west-northwest. More of a warm
frontal passage as warmer air in the low levels moves in for Sunday
and highs should be some 15-20 degrees warmer than Sat. After that
temperatures should climb ever so slowly Monday through Wednesday. Could be
a weak back door cold front in the vicinity Wednesday with highs 10-15
degrees cooler in the northeast vs the southwest County Warning Area...but the front
should lift out later on Wednesday as the upper ridge continues to slide
east with the axis overhead by Thursday. Ec and GFS have next
upstream trough moving towards US Friday but they differ in the
timing with the GFS a bit faster. Neither model generating much
precipitation ahead of the trough at this time but that will most likely
change in future runs.

Regarding temperatures...forecasts for 850 mb show a steady warmup
through the extended. Looking at a random point in the middle of the
County Warning Area...850 mb temperatures are slated to increase from the current value of
-4c to +15 or 20c by next Thursday or Friday. This alone would warrant a
large increase in temperatures but will temper those somewhat for now based
on a couple of factors. I would think we will see plenty of
sunshine late next week but a couple of the time height sections are
showing the possibility of an ample cirrus shield. Also...even if we
melt most of this snowpack...the soil is going to remain saturated
for awhile...slowly the warmup just a little. Still...the extended
looks quite nice as compared to the first few days of Feb.

&&

Aviation...(for the 00z kgri/kear tafs through 00z Saturday evening)
issued at 603 PM CST Friday Feb 12 2016

This is a difficult taf forecast with low clouds likely to
eventually move in and the possibility of lower ceilings
especially further west. Kear and kgri should both have periods of
MVFR ceilings through the night and into Saturday morning before
ceilings more consistently rise back to VFR Saturday afternoon.
In addition...there is at least a slight chance of freezing
drizzle after midnight tonight through Saturday morning primarily
from Kearney west...but can not rule it out in the kgri area.

&&

Gid watches/warnings/advisories...
NE...none.
Kansas...none.
&&

$$

Short term...pfannkuch
long term...ewald
aviation...wesely

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