Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 211230
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
730 AM CDT Sun Apr 21 2019

.SHORT TERM...(Today through Tuesday)
Issued at 333 AM CDT Sun Apr 21 2019

Chances for thunderstorms later today and tonight, then cooler
temperatures to start the work week, are the primary forecast
concerns.

Mid level ridging across the Plains Saturday night will breakdown
today as upper trough settles into the Southwest CONUS and ejects a
lead shortwave into Mid America through tonight. Surface cold front
extending from western Minnesota into southwest South Dakota is
forecast to drift southeast into northeast Nebraska later today,
then ushered through the rest of eastern Nebraska and southwest Iowa
by Monday morning as shortwave aloft swings northeast.

Southwest flow aloft today will continue to promote low level theta-
e advection from the Southern Plains into the Mid Missouri Valley.
Mid to upper 50s surface dew points are forecast to spread through
Kansas and into eastern Nebraska late today, and with
temperatures likely topping 80 over most of the CWA, SBCAPE
values over 1500 J/kg are expected by 00Z. However forecast
soundings are still showing nose of warm air above surface layer
which will effectively cap any convection over much of eastern
Nebraska through the afternoon. Parts of northeast Nebraska near
and north of cold front and nearer cooler mid level temps may see
convection this afternoon. Better chances for more widespread
convection should hold off until this evening when mid level lapse
rates steepen further and surface convergence is enhanced by
advancing cold front and ahead of surface low center propagating
along front into eastern Nebraska as per GFS and ECMWF. Degree of
instability and temperature profiles suggest some strong storms
with hail and damaging winds are possible, however widespread
severe is not expected given modest shear profiles.

Bulk of convection should be moving off to the northeast Monday
morning as shortwave and attendant surface low shift into Iowa and
beyond. Scattered showers may linger into the afternoon as mid level
flow overrides cooler surface air, but main weather story Monday is
cooler temperatures on gusty northwest winds. Surface high pressure
settles into the region Monday night and lingers through Tuesday
with cool northeast winds prevailing.

.LONG TERM...(Tuesday night through Saturday)
Issued at 333 AM CDT Sun Apr 21 2019

The rest of the work week looks relatively mild with only spotty
rain chances. Southwest CONUS upper trough is expected to drift
through the Southern Plains into the Southeast by Friday, leaving
our area under influence of zonal northern stream flow from the
Pacific Northwest into the Great Lakes. Only weak shortwaves
rippling through that flow may trigger isolated showers from
Wednesday night into Friday, but coverage should be minimal. A
chance for thunderstorms returns Friday night into Saturday when
warm advection associated with rising mid level heights promotes
elevated mainly nocturnal convection.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 710 AM CDT Sun Apr 21 2019

Low level wind shear continues for a few hours this morning at
KLNK and KOMA then south winds pick up to 15 to 30kts during the
day. One disturbance is passing to the northeast early this
morning with thunderstorms remaining northeast of KOMA. Through
the day and tonight clouds will increase fl100-150. Another
shortwave will bring the chance for a few sprinkles or elevated
showers then showers and thunderstorms with the stronger forcing
tonight. Included TS at KOFK, however more smaller chances at
KLNK/KOMA. MVFR ceilings possible at 08Z as winds turn around to
the northwest.

&&

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

$$

SHORT TERM...Dergan
LONG TERM...Dergan
AVIATION...Zapotocny


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