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Forecast Discussion
NWS Omaha/Valley, NE

FXUS63 KOAX 151119

Area Forecast Discussion
National Weather Service Omaha/Valley NE
519 AM CST Thu Nov 15 2018

.SHORT TERM...(Today through Saturday)
Issued at 314 AM CST Thu Nov 15 2018

Temperatures fell into the mid and upper 20s early this morning.
Skies remained clear across eastern Nebraska and southwest Iowa,
with light southerly winds.

Weak upper level ridging will build over the region this morning, as
a vigorous cutoff low drifts northeast from southeast Missouri into
southern Indiana. A weak cold front will move into the forecast area
today, bringing winds around to the north. Some locations could get
a little breezy, especially across far northeast Nebraska, where
gusts of 25-35 mph will be possible. Despite the northerly winds,
still expect highs to mix into the upper 40s in southwest Iowa
and mid to upper 50s across eastern Nebraska. Dry weather will
continue into Friday with southerly low level flow returning.
Highs will once again reach the mid 40s and 50s.

A stronger, arctic front will surge through the forecast area Friday
night and Saturday. Winds will whip around to the north once again
and become gusty.  Precipitation will move into the the area with
the frontal passage.  For now, it appears that rain will quickly
change over to snow as cold air rushes in.  There is a small
potential for some light freezing drizzle with this system, given
model soundings indicating dry midlevel air.  However, with
excessively dry air possible in the lower levels, it appears it
will be difficult to generate much QPF at all over our forecast
area. In fact the most recent run of the NAM leaves our CWA
completely dry. On the wetter end of the spectrum, the ECMWF
appears to indicate a rapid transition to all snow, but continues
to keep the best forcing just to the west and east of the forecast
area, similar to the GFS. Therefore, after collaborating with
neighboring offices, opted for a quick transition from light rain
to snow, with only a tenth or two of snow accumulation expected,
at most, in southeast Nebraska and southwest Iowa.

.LONG TERM...(Saturday night through Wednesday)
Issued at 314 AM CST Thu Nov 15 2018

Dry weather returns on Sunday, with a ridge building into the
central CONUS by midweek. Temperatures will rebound into the 30s
Sunday, rising to the 40s and 50s by Wednesday. Dry conditions
will prevail through the extended period.


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 515 AM CST Thu Nov 15 2018

Expect VFR conditions through the period. Southerly winds will
turn to the northwest as a weak front pushes through the region





NWS OAX Office Area Forecast Discussion

Forecast Discussion
NWS Hastings, NE

FXUS63 KGID 151146

Area Forecast Discussion
National Weather Service Hastings NE
546 AM CST Thu Nov 15 2018

Issued at 409 AM CST Thu Nov 15 2018

Upper air and water vapor analysis shows a vigorous low pressure
system over the Mid MS River Valley. This system will get kicked
NE due to the next upper level disturbance currently along
US/Canada. Locally, the upper level flow is transitioning from N
to NW. At the sfc, a trough extends from the northern U.S. system
SSW into central High Plains, including the western CWA. Current
temperatures are fairly uniform in the mid 20s to low 30s, with
lgt srly winds keeping temps steady despite clr skies.


.SHORT TERM...(Today through Friday)
Issued at 409 AM CST Thu Nov 15 2018

Generally quiet and mild with plentiful sunshine expected through

We managed to meet or even exceed the warmest guidance yesterday,
and with that mind, bumped up highs today to once again closely
match the warmest guidance. This may still be a deg or two too low
given depth of mixing per forecast soundings. The biggest change
in the short term, however, was raising winds this aftn. Think
RAP/GFS have a better handle on mixing (NAM far too low - perhaps
due to how its handling snow melt to S and resultant impacts on BL
mixing), and both models suggest the potential for wind gusts
35-40 mph this aftn. This seems reasonable given mixing to H85 and
the greatest (albeit relatively modest) pressure rises rolling
thru during peak heating. Strongest winds should be along/N of
I-80, particularly in the ODX area. Clear skies and lgt winds are
expected tonight.

Should see one more nice day on Fri before sharp changes arrive
with a cold front Fri eve and overnight.

.LONG TERM...(Friday night through Wednesday)
Issued at 409 AM CST Thu Nov 15 2018

The main story for the extended will be sudden return to wintry
conditions on Sat then moderating temps early next week.

Fri night thru Sat night continues to look like the most
impactful weather over the next 7 days. An upper level ridge will
build over the Pac NW, resulting in amplification of the flow
downstream over NA. This will result in a shortwave trof and
strong surge of cold air to stream S out of Canada Fri night into
Sat. The main issue, initially, will be the surge of winds. After
collaboration with neighboring offices, have raised winds for Fri
night/early Sat as models show pressure rises on the order of
6-7mb/3hr. This should lead to gusts around 35mph, perhaps higher
for a few hrs.

The initial cold frontal passage appears mainly dry attm.
Forecast soundings show good saturation above H6 and below H85,
but have a significant dry air in the H85-H7 layer Sat AM. The
lowest saturation layer does not appear deep enough to produce
freezing drzl with only 1-2hrs showing cld bases below 1K ft. With
time, some forecast models show increasing saturation in the
previously dry H85-H7 layer, but not until later in the day
(mainly 18Z Sat to 06Z Sun) and mainly for areas along and S of
Hwy 6. There is still some model uncertainty in this, however, as
the NAM is completely dry whereas the operational EC is on the
higher end of QPF. Tend to favor the drier solutions given the
source of disturbance as well as open, fast-moving nature of the
wave. Also, to op EC is on the high end of its own ensemble
members. So, after coordinating with surrounding offices, have
opted to exclude any freezing rain/drizzle at this time and go
with primarily lgt sn. The best chc for lgt snw and lgt
accumulations appears to be over the S/SW CWA, mainly along and S
of Hwy 6. This should be a sub-advisory level event.

Daytime highs on Sat likely remain in the 20s for most with cold
wind chill readings in the single digits and teens. Should see a
modest incr in temps Sun, though will still be well below normal.
Will see temps continue to moderate early next week and may even
see above normal temps return for Tue-Wed with highs returning to
the 50s.

Peeking ahead to Thanksgiving Day, there is good ensemble
agreement in at least near normal temps near 50. Latest EPS is
even warmer in the mid 50s. Plenty of time to refine specific
temps, but NOT expecting any significant travel impacts from cold,
wintry weather leading up to the holiday.


.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Friday)
Issued at 543 AM CST Thu Nov 15 2018

Significant wx: gusty NW winds this aftn.

VFR. Have increased winds for this afternoon in latest forecast
package. Models now indicate winds may gust up to 30 kts this
afternoon, mainly in the 19Z-22Z time frame. Speeds are forecast
to fall below 10kt this eve. SW winds now will veer to W mid-
morning then NW around midday. Should be clr other than a few
high clds this morning. Confidence: High.





NWS GID Office Area Forecast Discussion