Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

345
FXUS63 KOAX 221952
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
252 PM CDT Sat Jul 22 2017

.SHORT TERM...(Tonight through Monday)
Issued at 224 PM CDT Sat Jul 22 2017

Northerly winds have taken over the forecast area as of mid
Saturday afternoon. Cooler temperatures have been filtering in as
well, but have been slow to do so in southeast NE and southwest IA
where heat indices in the 100-112 range persist. The good news is
that the cool air advection will be persistent and eventually win
out with lower dewpoints and temperatures gradually building into
the area this evening. Widespread cloud cover has also overtaken
most areas north of I-80 as the mid level moisture plume streams
overhead. There have been a few showers and even a couple rumbles
of thunder associated with this moisture but much of the
precipitation evident in radar reflectivity imagery has not been
reaching the ground as the airmass between 1000-12000 feet remains
hot and quite dry. The potential for a few showers and even a
thunderstorm will continue over western and southern parts of the
forecast area.

At this time, it appears that stronger surface based convection
will be focused very near or more likely south of the NE/KS border
as the surface-based cap strengthens quickly with northward
extent. With that said, if surface based storms do develop within
the forecast area, there is ample instability (on the order of
6000 J/kg) available and 20 to perhaps 30 kts of effective shear
which could support periods of storm organization with an
attendant damaging wind and hail threat. Should note that while
the surface front and cumulus field extends across the northern
tier of KS counties at 245 PM, the impressive instability field
does extend north of the front and this low-end severe potential
also extends about 80 miles to the "cool" side of the surface
front.

Any precipitation chances will gradually diminish and shift
farther south overnight with low temperatures ranging from the mid
60s north to the low 70s south. Sunday, while cooler, will still
be a few degrees warmer than normal with highs in the upper 80s to
lower 90s. Heat indices will hold in the 90s though as the airmass
will have much lower dewpoints. Monday will be near normal for
temperatures with dry conditions expected both Sunday and Monday.

.LONG TERM...(Monday night through Saturday)
Issued at 224 PM CDT Sat Jul 22 2017

Tuesday into Wednesday are now looking to be the hottest days of
the coming week but still with a consistent signal for conditions
to NOT be as hot as this past week with maximum heat indices
probably in the 100 degree range at times but unlikely to approach
110. Will also have some rain potential Monday night into
Wednesday. First a small chance for showers or a few thunderstorms
over primarily northeast Nebraska Monday night as a compact
vorticity maximum is forecast by all large scale models to track
near the NE/SD border on Monday evening. The main limiting factors
with this system seem to be cap strength and presence of enough
moisture for widespread convection. The better precipitation
chances come late Tuesday into Wednesday as a strong short wave
trough moves across the Great Lakes. This trough appears likely to
be strong enough to have its effects felt well southwest
circulation center where associated vertical motion will interact
with the modified monsoonal moisture plume over the local area.
This should result in one of the better chances for widespread
thunderstorms this week...although far from a slam dunk at this
point.

The cold front associated with the Great Lakes short wave trough
looks to be fairly strong and should push all the way through the
forecast area. This will set up a good chance for a period with
highs in the mid 80s and lows in the 60s, but also increases the
likelihood for a dry end to the week and first half of the
weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1211 PM CDT Sat Jul 22 2017

Low clouds and some patchy fog were slow to burn off this morning
but VFR conditions will prevail through this TAF cycle. Northwest
surface winds will become light and variable through the overnight
hours as a weak are of high pressure moves overhead.


&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Heat Advisory until 7 PM CDT this evening for NEZ045-052-053-
     065>068-078-088>090.

     Excessive Heat Warning until 7 PM CDT this evening for
     NEZ091>093.

IA...Heat Advisory until 7 PM CDT this evening for IAZ055-056-069-079.

     Excessive Heat Warning until 7 PM CDT this evening for IAZ080-
     090-091.

&&

$$

SHORT TERM...Barjenbruch
LONG TERM...Barjenbruch
AVIATION...Kern



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.