Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 171741
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1141 AM CST Fri Feb 17 2017

.SHORT TERM...(today through Sunday)
Issued at 241 AM CST Fri Feb 17 2017

A temporary rex block will continue over the Plains into the
weekend with a cutoff cyclone moving slowly across the Gulf Coast
and an upper-level ridge over the central and northern Plains.
This will continue to provide record setting warmth to the area.
Surface low pressure, the reflection of a shortwave trough moving
into southern Canada, will move across the Dakotas today with a
surface trough dropping through the CWA. Along and ahead of the
trough the surface to 850 mb flow will turn southwest allowing for
good mixing within the 850 mb thermal ridge. This should allow
for highs today to be 3 to 6 degrees warmer than we saw on Thu
with record highs likely at KOMA/KLNK. The trough will pass
tonight with a surface ridge over the area on Sat. With full
sunshine and a very dry atmosphere in place we should again see
good mixing with highs still making it into the 60s.

Height falls moving into the west coast tonight will eventually
emerge onto the Plains Sunday into Monday. Deep southerly flow
ahead of the trough will likely lead to some increase in clouds on
Sunday. Nevertheless with a very warm atmosphere in place we
should still see highs reach the mid 60s most areas.

.LONG TERM...(Sunday night through Thursday)
Issued at 241 AM CST Fri Feb 17 2017

Moisture will continue to increase on Sunday night associated
with a 40-50 kt low-level jet. Isentropic upglide within this jet
may lead to a few showers overnight /although the moisture depth
is pretty marginal/. Lapse rates do steepen overnight Sunday and
thus isolated thunder was added to the forecast. The better lapse
rates do shift east during the day on Monday, but the synoptic-
scale forcing does increase during the day with the passage of the
front and upper level trough. Thus we removed the thunder mention
during the day on Monday, but scattered showers, especially in the
eastern CWA appear possible.

Behind this system we will likely see record highs again on
Tuesday. The 850 mb flow becomes west, which should lead to great
mixing yielding highs in the lower 70s. Warm temperatures appear
to continue into Wednesday although highs are likely to be a touch
cooler after another weak boundary on Tuesday night. The upper
level flow then becomes southwest toward the end of the period
with the chance for rain increasing toward next Thursday with some
cooler temperatures.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1140 AM CST Fri Feb 17 2017

VFR conditions expected at all three TAF sites through the
forecast period. H5 ridge axis moving east, allowing broad area
of southwest flow to expand into the forecast area. Surface cold
front moving into northwest corner for forecast area, and will
cause winds to shift from southwest to northwest as the front
moves southward across the region. Surface pressure gradient is
modest, thus expected windspeeds only in the 5-10kt range with
some potential for occasinal gust up to 20kt due to diurnal
mixing. Frontal passage will be dry, as such no restrictions to
visibility and little or no cloud cover.

&&

.FIRE WEATHER...
Issued at 241 AM CST Fri Feb 17 2017

Very high fire danger is expected today. The most critical area
will be just ahead of an advancing surface trough over southeast
Nebraska. Here afternoon dewpoints will likely drop into the
upper 20s, and with highs in the lower to mid 70s we will see
minimum RH values of <=20% for a couple of hours. The limiting
factor for the issuance of a RFW is the wind. Southwest winds of
10 to 20 mph are expected, but we should generally not see the
wind speeds of 25+ mph in this area of minimum RH. Nevertheless
given the fuels and very low RH, any fires that occur will have
the potential to be difficult to control. Low RH is again expected
on Saturday with some improvement on Sunday. Tuesday is another
potential very high fire weather period day as well.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

SHORT TERM...Boustead
LONG TERM...Boustead
AVIATION...Fortin
FIRE WEATHER...Boustead



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