167
FXUS63 KOAX 160855
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
355 AM CDT Sun Jun 16 2024

.KEY MESSAGES...

- Hot temperatures expected today with afternoon highs in the
  middle 90s and afternoon heat index values 98 to 102.

- A chance storms remains in the forecast tonight through Monday
  night for northeast Nebraska. Severe storms will be possible,
  along with locally heavy rainfall.

- Hot temperatures continue Monday with highs in the lower 90s
  and afternoon heat index values 95 to 100.

- Strong and possibly severe thunderstorms are expected Tuesday
  into Wednesday, along with locally heavy and possible flooding
  rains. Rain chances continue every day Thursday through Saturday.

&&

.DISCUSSION...
Issued at 355 AM CDT Sun Jun 16 2024

Scattered thunderstorms continue early this morning across southeast
NE and southwest IA. Other than a storm or two lingering near
Falls City 6-7 am, the remainder of the day will be dry with hot
temperatures developing. Highs are forecast to mostly reach the
lower to middle 90s with southerly breezes at 15 to 25 mph,
with dewpoints rising into the upper 60s to lower 70s. This does
create afternoon heat index values from 98 to 102, which also
creates elevated heat risk, but heat index values remain just
below our official advisory criteria of 105. The southerly
winds will help mitigate the heat at least a little. There is
cold front that is forecast to move into northeast Nebraska this
afternoon, so areas north of a line from Albion to Wayne should
only reach the middle to upper 80s.

This frontal boundary will be the focus for potential
thunderstorm development tonight for areas north of Interstate
80. However, there remains some question whether any
precipitation will develop at all. Some of the CAMs do not
generate any precipitation, but some do, as does the GFS and
ECWMF. If storms develop, SPC has placed much of the area north
of I80 in a marginal risk for severe storms, with a slight risk
for severe storms near the SD border. And given that some of
northeast NE received 3-5 inches of rain yesterday evening,
there could be an additional flood threat with another 1-2
inches of rain expected. Given the uncertainties of whether it
would even rain or not, will hold off on a flood watch for now,
but will pass on to the next shift about the concern.

If the storms develop, then they could continue through the day
Monday for northeast NE, with a continued marginal risk for
severe storms. The other concern for Monday will be continued
hot temperatures, with highs in the lower 90s, dewpoints still
in the upper 60s, and afternoon heat index values 95 to 100.
Southerly winds Monday continue to strengthen to 20 to 35 mph
with gusts up to 40 mph possible. And the strong winds continue
Monday night. Believe most of the area Monday night should be
dry, but the NBM blend would maintain a slight chance of
thunderstorms in northeast NE as indicated by the ECMWF, but all
other models remain dry.

Tuesday will be another active weather day as a strong front
moves into the region. This front will likely trigger
thunderstorms by the afternoon, with Pops increasing to 60 to
90% Tuesday night, with storm chances continuing into Wednesday
at the front stalls across southeast NE and southwest Iowa. SPC
has placed the region in a day 3 marginal risk for severe
storms, but realistically, it will probably need to be upgraded
to a slight. And WPC has the entire area in a slight risk for
excessive heavy rainfall, with a widespread 1-2" forecast by
Wednesday morning. Again, given the recent heavy rains in
northeast NE, there will likely be a few counties that could be
especially susceptible to flooding.

That same stalled frontal boundary then lifts northward as a
warm front Wednesday night into Thursday, which brings
additional thunderstorms, and possibly a severe weather risk
along with the potential for heavy rains.

Rain chances do remain in the forecast for Friday and Saturday,
but confidence remains low in the details that far out. The
aforementioned frontal boundary could very well lift north of
the region and the area could remain dry per the ECMWF, but the
GFS has another shortwave which pushes the frontal boundary back
into the area and brings another chance of rain. Bottom line,
the blends maintain a 20-30% chance of storms both days.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1030 PM CDT Sat Jun 15 2024

Strong low-level wind shear will be in place across eastern
Nebraska and western Iowa (all TAF sites) through 12 UTC.
Afterwards, VFR conditions and southerly winds at 12 to 20 knots
will prevail at all TAF sites. Sporadic gusts up to 30 knots
will be possible, though the low frequency of these gusts
precludes their inclusion in the TAFs as prevailing conditions. There
is the potential for isolated thunderstorms across northeast
Nebraska after 00Z (KOFK), however probabilities are not high
enough to include in TAFs at this time.

&&

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

&&

$$

DISCUSSION...DeWald
AVIATION...Darrah