Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 162303
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
603 PM CDT Sun Jul 16 2017

.SHORT TERM...(Tonight through Wednesday)
Issued at 330 PM CDT Sun Jul 16 2017

The main forecast issues in the short term will be chance for
thunderstorms...temperatures...and heat headlines.

The latest surface map had temperatures again in the 90s with a
weak surface boundary near Norfolk to Harlan where readings were
closer to 90. Heat index values are mostly 95 to 100...however
local conditions has them variable with some high and some lower.
Visible satellite imagery had a few cumulus in our area with a
few thunderstorms in southeast Iowa and west central Iowa closer
to where a shortwave is passing through the region. WSR-88D radar
reflectivity shows thunderstorms in the upslope region in
northeast CO and near Ottumwa and southeast Iowa.

The main storm track for the short term will be over the Northern
Plains, however a pesky area of low pressure in the mid levels
currently over eastern Colorado is forecast to drift eastward
during that time. Water vapor satellite imagery does a nice job
depicting the ridging across the central U.S. into Canada and
shows the moisture over parts of the southwest U.S. into
CO/western Kansas.

The 12Z OAX sounding this morning had 1.13 PWAT. PWAT values in a
narrow area into to 1.25" then drop for Monday ahead of the
moisture with the pesky low.

The RAP has been overdoing the precip today and the HRRR/RAP try
to build echoes back toward southwest Iowa late this afternoon.
The satellite shows a few cumulus from Pottawattamie Co. eastward
and could see something isolated develop. For now will leave dry
and pass on to the evening shift to metwatch.

As the H5 trough breaks down the ridge over the Northern
Plains...the H5 low press drifts into western Nebraska Monday
morning and central/parts of northeast and east central Nebraska
Monday afternoon. Outside of the clouds...southwest flow and very
warm h85 temperatures should keep highs in the 90s. Isolated
thunderstorm chances will spread into northeast Nebraska by 00Z
with chance pops overnight for all but southeast Nebraska and
southwest Iowa. Rain chances linger for Tuesday and Tuesday night,
however the coverage appears better to the north of the area. The
lingering clouds could hold temperatures back, however with the
main front still to the north...have highs again in the 90s.

Hot temperatures return for Wednesday and highest heat index
values from 100 to 110. Considered an excessive heat watch,
however with isolated to scattered showers and thunderstorms in
the forecast Monday night through Tuesday night and this
convective activity could affect boundaries and where the highest
heat would be later in the week, decided to hold off.

.LONG TERM...(Wednesday night through Sunday)
Issued at 330 PM CDT Sun Jul 16 2017

A large area of low pressure is forecast to encompass Hudson Bay
with a faster flow across the Northern Plains and a large area of
h5 pressure over the central and southern U.S. Hot temperatures
are forecast for Thursday and there is still some timing issues
related to ripples in the flow across the Northern Plains which is
forecast to bring some relief from the heat this weekend along
with spotty chances for rain.

Highs Thursday and Friday 89 to 100 and 85 to 95 for the weekend.
Highest heat index values could range from 100 to 105 Thursday and
Friday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 602 PM CDT Sun Jul 16 2017

VFR conditions are forecast through Monday evening with only
scattered high clouds and light southeast to south winds under
10kt.

&&

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

$$

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



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