Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 201725
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1225 PM CDT Sun May 20 2018

.UPDATE...
Issued at 1222 PM CDT Sun May 20 2018

Updated the forecast earlier in the morning to lower temps a
couple of degrees from previous forecast. Not much diurnal rise
today with cloudy gray skies and scattered showers. Highs running
about 15 degrees below normal. Clouds should break from west to
east Monday morning.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 315 AM CDT Sun May 20 2018

Precipitation chances today and tonight, then from Monday night
into Wednesday will provide the main forecast challenges in the
short term. Temperatures are also a concern.

Large scale mid level pattern featured a weakly closed low over
north central NE and a general southwest to northeast flow from
the southwest US into the central and southern parts of the
Plains. Several weak disturbances were embedded in that flow. At
the surface, a nearly stationary front extended westward into a
low pressure center over western IL, the southwest into another
low in southeast KS. High pressure stretched from ND into western
SD and western NE. Our area was in northerly low level flow.
Regional radar loop early this morning showed some scattered
showers and isolated thunder working eastward.

High pressure at the surface to our west will gradually move east
today and tonight, with precipitation chances slowly decreasing
through that period. Highs today will be held down due to cloud
cover and intermittent precipitation. Spotty showers should
develop during the afternoon, as highs reach around 60 in
northeast NE and then 62 to 69 in southeast NE and southwest IA.

Monday should be dry with at least partial sunshine and highs from
around 73 to 78. High pressure will continue to move eastward late
Monday into Monday night with return flow strengthening. Models
show isentropic upglide increasing Tuesday night in the 300-310 K
layer. Of the 00Z models, the GFS was the most aggressive with
development of precipitation Monday night. Generally followed the
GFS pattern but with lower POPs and lower QPF into Tuesday.

.LONG TERM...(Tuesday night through Saturday)
Issued at 315 AM CDT Sun May 20 2018

By Tuesday evening, models are in good agreement showing a Rex
block from southwest Canada into the western US. Closed low at
500 mb should be back over NV, with a shortwave ridge from MO into
SD. That low will track northeast toward western ND through
Thursday night, keeping our area in southwest mid level flow.
Several disturbances will track through the region with chances
for showers and thunderstorms. Temperatures from Wednesday into
Saturday should be above normal, with highs in the 80s and lows
from around 60 to the mid 60s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1222 PM CDT Sun May 20 2018

MVFR conditions with scattered showers for the first half of the
TAF period. Could even go back down to IFR for a time, and
possibly even LIFR at KOMA late in the night. Clouds scatter out
to VFR from west to east Monday morning.

&&

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

$$

UPDATE...DeWald
SHORT TERM...Miller
LONG TERM...Miller
AVIATION...DeWald


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