Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 171735
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
1135 AM CST Fri Feb 17 2017

.UPDATE...
Issued at 920 AM CST Fri Feb 17 2017

Just published a fairly "cosmetic" forecast update for the rest of
today, with the main impact regarding fire weather concerns...

Kudos to preceding night shift for at least introducing "near-
critical" fire weather concerns to the Hazardous Weather Outlook
(HWOGID) for our northwestern CWA. However, after updating this
afternoon`s wind/dewpoint/relative humidity (RH) expectations
with some of the latest data, it now appears that a greater
coverage of near-critical conditions should materialize this
afternoon, especially 1-4 PM. The most "solid" area for near-
critical concerns should be roughly northwest of a Beaver City-
Fullerton line, where although RH could be just a touch higher
than other areas, wind gusts are most likely to reach at least
20-25 MPH out of the northwest behind weak cold front. Meanwhile,
in our far southeast zones, a separate area of near-critical is
now expected with RH falling to around 20 percent and southwest
winds gusting to around 20 MPH ahead of the invading boundary. In
theory, the "safest" area from fire weather concerns today should
favor a northeast-southwest oriented stripe across the heart of
the CWA where winds should be lightest, but even here, RH falling
to around 20 percent makes fire danger "non-zero" as well. All of
this taken into consideration, we have/will be updating the HWO
and also the Fire Weather Forecast (FWFGID) products to at least
expand/hit the "near-critical" fire potential a little harder.
Fortunately, outright critical conditions that would require
potential Warning issuance are still not expected, but it could be
a fairly close call especially in our extreme west Nebraska zones.

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

&&

.SHORT TERM...(Today and tonight)
Issued at 250 AM CST Fri Feb 17 2017

Warm February weather continues today with record or near record
high temperatures. A dry, warm airmass was in place across the
central plains early this morning under the influence of upper
ridging across the northern and central plains. The upper ridge
axis will translate east through the day as a shortwave trough
tracks across the northern plains, dragging an associated cold
front south through our region. The front is progged to reach our
western zones this morning and our southeast zones toward
evening. Have followed closer to the rap for highs today with
readings ranging from the mid/upper 60s in our northwest zones to
the low/mid 70s in our southeast zones. These readings are a solid
30 degrees above normal for this time of year and will be in
record territory with records standing 71 degrees for KGRI and 74
degrees for KHSI.

Forecast soundings indicate post frontal mixing in our western
counties near h85 with winds at the top of the layer around 20kts
and cannot rule out a couple of hours with wind gusts near 20 mph or
so and combined with low relative humidity values in the low 20th
percentile, will mention near critical fire weather conditions in
the HWO for locations west of a line from Elwood/Lexington to
Ord.

.LONG TERM...(Saturday through Thursday)
Issued at 250 AM CST Fri Feb 17 2017

Saturday will be only slightly cooler than yesterday and today, but
still very mild for this time of year. Ridging and southerly flow is
expected to increase again on Sunday. Because of this, we will have
to monitor the  potential for fog as low level moisture advects into
the area Sunday morning. Given some uncertainty on coverage/location
I opted to leave it out of the forecast for now, but I wouldn`t be
surprised if we at least have some lower visibilities during that
timeframe.

An upper-level trough will swing into the area Sunday night. Rain
showers will be possible starting Sunday night into Monday. While
there is some instability, thunderstorms continue to look unlikely.
Some uncertainty remains on how quickly rain moves out of the area.
For now, I kept a slight chance of rain for the eastern half of CWA
into Monday afternoon, but if the GFS verifies, the entire area
would be dry by midday at the latest. Tuesday will likely be the
warmest day next week, as high temperatures reach the 70s before a
front pushes through the area Wednesday morning.

Another storm system may impact the area starting next Thursday.
There is a growing consensus that a low will track across western
Kansas into Nebraska Thursday into Friday. Impacts to our area will
be very dependent on the specific track of the system. Of course
there is still considerable uncertainty given the timeframe. Even
though details are likely to change, it currently looks like it will
be primarily rain, possibly changing over to some snow for Friday.

&&

.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Saturday afternoon)
Issued at 1135 AM CST Fri Feb 17 2017

Confidence remains extremely high in VFR ceiling/visibility
through the period, with only limited passing high clouds mainly
during the latter half. That leaves surface winds as the main
issue. The strongest breezes, sustained around 12kt from the
north-northwest with gust potential closer to 20kt will occur
right away this afternoon behind a passing, weak cold front. By
late afternoon, sustained speeds will ease back 10kt-or-lower and
remain northerly through the night. Late in the period on Saturday
morning, have indicated more of a light/variable regime as
direction transitions from northerly to easterly.

&&

.CLIMATE...
Issued at 315 AM CST Wed Feb 16 2017

Records for February 17th for Grand Island and Hastings

February 17th Record Highs
Grand Island.....71 degrees in 1981 & 1970
Hastings.........74 degrees in 1981

&&

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

$$

UPDATE...Pfannkuch
SHORT TERM...Fay
LONG TERM...Mangels
AVIATION...Pfannkuch



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