Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 191006
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
506 AM CDT Sat May 19 2018

.SHORT TERM...(Today through Monday)
Issued at 320 AM CDT Sat May 19 2018

Main concerns again are thunderstorm coverage and intensity today
into tonight and potential for severe storms. SPC Day 1 Outlook
seems on track.

Mid level pattern had one shortwave off to our east and several
ripples moving out of trough to the west. Main low appeared to be
back over southern CO according to water vapor satellite imagery
early this morning. MCS that formed to our west and southwest last
evening continued to lift northeast, with a couple of MCVs noted
in the regional radar loop. Some showers and isolated thunder have
also been over parts of northeast NE early this morning. Much of
the short range high resolution model guidance lifts the remnants
of the MCS across our area this morning, which seems reasonable.
Have used recent runs of the experimental HRRR and SPC HRRR to
time the precipitation this morning.

High pressure building southeast across the Northern Plains will
bring colder air south over the area. Have adjusted highs down a
bit especially for northeast NE, to a few degrees either side of
60. The far southeast corner of NE could still reach near 80.
Coverage of showers/storms should start to increase again in the
3 to 5 pm window. Storms should then linger into the evening.
Initially, storms may be somewhat discrete with potential for
large hail and possibly a few tornadoes. Convective mode then
should turn more linear with time. Details on just how warm it
gets at the surface in southeast NE and southwest IA will depend
on the frontal location. Those things will be important in
regards to how much severe weather occurs. Shear should be
adequate for rotating updrafts and current 0-1 km ML CAPE values
could reach 2000-3000 J/kg.

Generally felt the 00Z GFS solution seemed reasonable in regards
to precipitation potential for later tonight into Sunday and
Sunday night. Sunday will be cool with highs mainly in the 60s for
our area. Monday looks mainly dry at this time, and warmer
with highs in the 70s.

.LONG TERM...(Monday night through Friday)
Issued at 320 AM CDT Sat May 19 2018

At the start of this period, will will be in fairly zonal flow
locally, but a closed low will be back across the southern parts
of CA and NV. That low should slowly open up and lift out toward
MT and WY by Thursday.

Several shortwave troughs are expected to affect the nations mid
section next week with chances for showers and storms. Although
the operational GFS and ECMWF are in fair agreement with the
pattern, then differ on timing and details. Expect highs to
average in the lower and mid 80s with lows in the 60s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 505 AM CDT Sat May 19 2018

Bands of showers and thunderstorms will lift northward today,
however their duration and coverage will be very transient. The
trend is for the bands to lift and weaken over much of the area
then re-invigorate this afternoon. VFR conditions with some MVFR
vsbys/cigs associated with the heavier rain/tstorms. MVFR/IFR
conditions at near KOFK today expand southeastward to KLNK and
KOMA tonight. Northeast surface flow continues through the day.

&&

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

$$

SHORT TERM...Miller
LONG TERM...Miller
AVIATION...Zapotocny



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