658
FXUS63 KOAX 181030
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
530 AM CDT Tue Jun 18 2024

.KEY MESSAGES...

- Strong thunderstorms are expected Tuesday into Wednesday with
  severe weather possible. Locally heavy rains and flooding
  accompany the convection.

- Rain chances continue every day Tuesday through Saturday.

&&

.DISCUSSION...
Issued at 400 AM CDT Tue Jun 18 2024

Quick southerly winds are gusting 20 to 30 mph at times and are
helping to prop up overnight temperatures. Most locations are
still holding upper 70s with plenty of lower-80s mixed in.
Lincoln and Omaha have lost 1-2 degrees over the past five
hours (11p to 4a). A non- diurnal temperature curve has been
forecast with high temps in northeast Nebraska happening before
noon as the meridional flow pushes a cold front through the CWA.
Numbers will slip after frontal passage. The front should
arrive at Lincoln and Omaha by 6pm as it`s equatorward push
begins to slow.

Believe convection will wait til the afternoon when convective
temperatures will be met with 2000-3000 J/kg of CAPE available
just ahead of the front. Temperatures at 850/700 hPa will slip
through the morning as surface temps warm and dewpoints hold
near 70. Low-level lapse rates will quickly grow as a result.
Kinematics are best behind the front, despite the slower
northerly surface winds behind the sinking front. Still
expecting a line of convection with some supercells possible
along the front, especially in the afternoon and evening with
maximum buoyancy and broad forcing for ascent with the area
under the 500 hPa jet`s right rear quadrant. Widespread severe
weather seems less likely than the need for a few warnings for a
couple of the strongest cells. Maybe flood warnings will
outnumber convective warnings.

Flash flooding will be a legitimate concern. Forecast PWAT
values of 2" are in the 99th percentile for mid- June (NAEFS)
and storm motion should be slow, especially prior to the cold
pool development. QPF of 1.5-2" will be common with the HREF`s
LPMM product producing some 4-5" values (currently a bullseye
near Omaha and two others near Fairbury, NE and Falls City,
NE). With mean winds of 850-250 hPa nearly parallel to the
front, expect to see training storms and little front
propagation.

QPF accumulation should slow overnight and into Wednesday
morning, though flooding concerns will linger as the totals add
up.

.WEDNESDAY and THURSDAY...

With the front still draped across the area busy southwesterly
flow with weak disturbances will set the stage for additional
PoPs. Best chances will be with the day`s maximum heat. Severe
weather isn`t anticipated. Wednesday`s QPF has slipped as has
WPC`s category for the day (Slight excessive rainfall outlook
is now a "marginal").


.THE WEEKEND...

The surface ridge on the East Coast becomes less amplified and
grows elongated from west to east. Still expect to see some
moisture return through TX and KS and the ridge`s western edge
and with continued southwesterly flow from SoCal through the OAX
CWA, chance PoPs are warranted for Friday and Saturday with best
forcing in the northern half of the area. Sunday`s pattern
change brings a weak and transitive ridge through the central
CONUS and a break in the chances for precip.

June`s temperatures are already above 1991-2020 norms. Highs
near 90 from Friday through next week will help drive the
month`s averages even higher. (They`ll eventually influence
2001-2030 norms, too!)

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 527 AM CDT Tue Jun 18 2024

An active TAF period coming up. Southerly winds 20-32 knots at
TAF issuance, with scattered to broken clouds 2500-3500 feet. A
cold front approaching from the west will bring a chance of
strong thunderstorms to all of the TAF locations, at KOFK
18-20z, KLNK 23-03z, and KOMA 00-04z. The arrival of storms will
also relaize a wind shift to the northwest to lower speeds
closer to 12 knots or less through the remainder of the TAF
period.

&&

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

&&

$$

DISCUSSION...Nicolaisen
AVIATION...DeWald