Area Forecast Discussion

FXUS63 KOAX 201132
Area Forecast Discussion
National Weather Service Omaha/Valley NE
632 AM CDT Tue Mar 20 2018
.SHORT TERM...(Today through Thursday)
Issued at 318 AM CDT Tue Mar 20 2018
A weak mid-level vorticity lobe and attendant precipitation band 
will translate through the area this morning with light rain
temporarily mixing with or changing to light snow before ending or
transitioning to drizzle as the stronger forcing for ascent shifts
east. The radar presentation as of 0800z is rather unimpressive 
with highest precipitation rates (~0.02-0.05/hr) associated with 
rain per surface observations. Based on current radar trends and 
latest short-term model guidance, any snow accumulation should 
remain low and generally less than a half an inch.
Lingering cloud cover and light precipitation (especially across
the eastern part of the CWA) will once again limit daytime heating
with highs today mainly in the lower to mid 40s. However by 
Wednesday, decreasing clouds coupled with building mid-level
heights will yield warmer temperatures with afternoon readings in
the upper 40s to upper 50s.
Wednesday night into Thursday, model guidance suggests that warm 
advection and isentropic upglide within the exit region of a low-
level jet will foster a swath of light rain across portions of
western into central IA, to the immediate north/northeast of a
weak surface warm front. Our southwest IA counties will be on the
western periphery of that precipitation where we will indicate 
slight-chance PoPs. To the west of the front, south to southwest 
low-level winds will allow temperatures to warm into the 60s with 
mid to upper 50s forecast along and to the east/northeast of the 
boundary from northeast NE into west-central IA.
.LONG TERM...(Thursday night through Monday)
Issued at 318 AM CDT Tue Mar 20 2018
Latest medium-range guidance continues to indicate an active
pattern over the mid-MO Valley through much of the extended
forecast period. These data suggest that an amplified ridge will
overspread the Great Plains Thursday night into Friday ahead of a
low-amplitude perturbation moving from the Rockies into the High
Plains. Strengthening warm advection ahead of that disturbance
will support a chance of light rain on Friday. By Friday night
into Saturday, it appears that the High-Plains disturbance will
amplify as it moves through the region, driving the deepening of a
surface low which is forecast to track to our south. Nonetheless,
steepening lapse rates and increasing moisture content will
support scattered showers and a few thunderstorms as the synoptic
system moves through the area.
On Sunday, a short-wave trough will traverse the northern Plains
with an associated surface cold front focusing precipitation
chances over the mid-MO Valley. By early next week, the GFS
progresses a low-amplitude trough through the central U.S.,
whereas the ECMWF and Canadian models depict broader troughing
lagging west over the Rockies. As such, forecast confidence is low
during that time frame.
.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 626 AM CDT Tue Mar 20 2018
IFR conditions will start off the period this morning through 18Z
as band of mixed precip associated with a weak mid level trough
moves across the area. After 18Z further weakening of the trough
is indicated along with a secondary wave over the northern plains.
MVFR conditions are expected to develop during this time and with
further translation east after 00Z VFR conditions are expected to
develop after 06Z.