Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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313
FXUS63 KOAX 151709
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1209 PM CDT Thu Apr 15 2021

...Updated Aviation Forecast Discussion...

.DISCUSSION...
Issued at 347 AM CDT Thu Apr 15 2021

Really similar early morning analysis to yesterday, with cutoff
lows to both the west (centered over the NV/UT/ID border
intersection) and to the east (centered over MI/Lake Huron). In
between was some weak upper level ridging, with the ridge axis
basically right along the eastern CO border. Most of the area
remained clear, allowing temperatures to drop into the upper 20s
and lower 30s as of 3 AM, though some mid level clouds were
pushing in from the west and some lower level clouds were
approaching from the north. Still, latest HREF guidance keeps
areas under the freeze warning mostly clear through an hour or 2
beyond sunrise, so from a headline perspective, seemed to work out
pretty well.

For today, just expect a general increase in clouds as mentioned
above. This should keep temperatures on the cooler side, with
highs mainly in the lower to mid 50s, though some spots across
northeast Nebraska could struggle to get out of the 40s.
Meanwhile, the low and associated precip off to the west will be
moving toward the area during the day, with latest short term
guidance suggesting the more widespread precip moves into the
forecast area later in the evening. That said, several CAMs
suggest the potential for some very light showers/sprinkles during
the afternoon, with latest RAP soundings showing a tiny bit of
instability in the cloud layer. However, with the area remaining
under the influence of surface high pressure and upper level
ridging through the day, think it will be somewhat tough to get
any precip before the low gets closer. Once it does move in, vast
majority should be rain, though still can`t rule out a few
snowflakes mixing in across parts of northeast Nebraska toward low
temperature time early Friday morning. Rain will gradually
overspread the area on Friday, potentially lingering into Saturday
morning before the system exits the area. Still looks like the
heaviest precip will fall south and west of the area, which is
where guidance shows the best isentropic upglide and strongest PV
advection track.

We`ll see a break from precip on Sunday but then a surface cold
front and upper level trough axis will slide through the area
sometime Monday, bringing the next shot of precip. Still a fair
amount of spread on if/when/where the front produces precip, but
enough ensemble members and operational models suggest precip at
least somewhere along the front that it warranted adding at least
some slight chances Monday into Monday night. Pending exact
timing, could once again see some snow mix in at times given
continued low temperatures in the upper 20s to mid 30s. The cooler
air behind the front will remain in place well into next week, as
highs look like they could struggle to get out of the 50s through
at least Wednesday, though still plenty of time to (hopefully)
add a degree or 2.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1204 PM CDT Thu Apr 15 2021

MVFR to low VFR cigs will continue to overspread eastern Nebraska
TAF sites through the afternoon, with cloudy skies and MVFR cigs
forecast overnight. A low pressure system emerging from the
Rockies overnight will increase rain chances across eastern
Nebraska, with rain moving into KLNK before 12Z, then KOFK and
KOMA by 15Z. Lowering cigs to below FL015 will be common as the
rain begins, with cigs lowering to IFR all sites by the end of the
TAF period. Vsbys should remain in the MVFR category in the rain.
North winds near 10kt should prevail through the TAF period.

&&

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

$$

DISCUSSION...CA
AVIATION...Dergan



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