676 
FXUS63 KOAX 150441
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1141 PM CDT Fri Aug 14 2020

...Updated Aviation Forecast Discussion...

.UPDATE...
Issued at 826 PM CDT Fri Aug 14 2020

Thunderstorms couldn't maintain themselves across most of eastern
Nebraska late this afternoon and early evening, with a storm just
west of our area becoming dominant and dropping south into north
central Kansas. Thus have cancelled all severe watches for our
area. Cold front was slipping southeast into the Omaha Metro area
as of 830 PM, with winds turning northwesterly. However surface 
dew points were slow to decrease. Latest few runs of hi-res model
output were still showing a signal that a few showers or isolated
thunderstorms could pop up as front slowly drifts southeast. No
severe expected, but maintained a small chance of occurrence
overnight.

&&

.DISCUSSION...
Issued at 213 PM CDT Fri Aug 14 2020

At 2 PM, there were two lines of thunderstorms draped over the 
region. The storms across the Omaha and Lincoln Metros were 
elevated prefrontal storms (no severe threat with these). The 
second line further north toward Norfolk was associated with the 
cold front, and consisted of more surface based convection. The 
main severe threat should be with this second line, hence the 
Severe Thunderstorms Watch issuance. 

This Evening & Tonight:

We will continue to monitor the potential for severe weather with a 
cold frontal passage this afternoon and evening. A perusal of CAM
data and current observations suggests ample instability ahead of
the front (Mixed layer CAPE > 3000 j/kg, DCAPE near 1200 j/kg, 
and 700-500 mb lapse rates > 8 C/km). Bulk shear profiles 
meanwhile should remain sufficient for a couple supercells (25 to 
35 kt of 0-6 km bulk shear), but lacking in the lowest 1-3 km. 
Thus the main expected hazards today remain hail and damaging 
downburst winds (tornados aren't expected). Generally thinking the
peak potential hail size would be ping pong balls, while an 
isolated wind gust to 70 mph can't be ruled out. The severe risk
in the Metros should be highest between 5 PM and 8 PM, and storms
should exit into Kansas/Missouri by midnight.

The Weekend:

Surface high pressure will settle over the region Saturday and 
Sunday, resulting in near to slightly below average temperatures, 
lighter winds and dry weather. Look for afternoon highs in the lower 
80s Saturday, then mid 80s Sunday. Light northeast winds Saturday 
should become southwest winds by Sunday afternoon. No hazardous 
weather is anticipated over the weekend.

Next week and beyond:

Guidance all continues to favor a bulbous ridge over the Western 
U.S. and a trough in the East next week. This places Nebraska and 
Iowa in a region of prevailing northwest flow aloft and likely 
sets us up for predominantly dry week with temperatures in the 
80s. If mother nature can see fit to send us rainfall, it would 
likely be associated with a weak shortwave riding over the apex of
the ridge. A scenario that suggests spotty rainfall at best. Thus
it isn't much of a surprise that WPC QPF for Days 4-7 suggests no
rainfall in our region. Toss in the CPC outlooks through Day 14 
and trends suggest few opportunities for drought relief over the 
next week or two.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1137 PM CDT Fri Aug 14 2020


VFR conitions are expected through the forecast period as surface
high pressure moves across the area.

&&

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

$$

UPDATE...Dergan
DISCUSSION...Albright
AVIATION...Smith