Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 251719
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1219 PM CDT Mon Aug 25 2014

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 346 AM CDT MON AUG 25 2014

Precipitation in last few hours seems to be tied to area of moisture
convergence around 700mb. NAM and GFS are consistent in this
convergence weakening over the next several hours and have played
the forecast in this manner but not a high confidence forecast.
Another area of thunderstorms was making its way ENE across northwest
Kansas and may enter the western counties later this morning with
modest flow over the stationary front, draped from northeast Kansas
into southeast Colorado. May see some uptick in activity later this
afternoon with again modest convergence along the front, though most
guidance generates little convection. Strong downburst winds and
marginally severe hail should again be the main concerns with deep
layer shear limited, even just behind the front. Low level temp
fields suggest air temps may be a bit cooler than yesterday in the
warm sector and temps shouldn`t be much cooler behind the front.
With dewpoints along it a bit higher, keeping the Heat Advisory
seems in order. With the Northern Plains anticyclone moving east,
moisture advection over the front in western Kansas looks to be
stronger than that of recent hours and support convection reaching
the northern counties tonight.

.LONG TERM...(Tuesday through Sunday)
Issued at 346 AM CDT MON AUG 25 2014

Thunderstorms may be ongoing mainly north of Interstate 70 Tuesday
morning north of the frontal boundary. Outflow from the storms along
the border may reinforce the front in the morning. The front is
forecast to lift northward during the day to near the Nebraska
border by evening. The synoptic boundary along with any outflow
boundaries left over boundaries from morning convection will be a
focus for afternoon convection. CAPE forecast to be in the 2000-2500
J/kg range and bulk shear of 20 to 25 kts along with conditional
lapse rates. A few storms may be strong to severe with strong wind
gusts and hail the main hazards. Will continue with best chances
across the north Tuesday. Increasing low level jet Tuesday night
will lead to an increase of convection north of I-70 with the best
chances along and north of the Nebraska border. Locally heavy
rainfall will also be possible as well as precipitable water
averages between 1.50 and 2.00 inches. Temperatures Tuesday will be
somewhat dependent on precipitation and cloud cover. Areas that have
the best insolation will see temps in the upper 90s while other
areas may see lower 90s. Given uncertainty will not extend the heat
advisory for now and see how things evolve to zero in on the
counties most likely to rise above 100 degrees in the afternoon.

Models are in decent agreement with the overall speed of the upper
trough as it is cut off from the main westerlies and slowly meanders
across the Central Plains through Saturday. Upper trough axis looks
to move through along with a cold front by Saturday evening with
Sunday looking dry. Temperatures will also be cooler with clouds
from nightly MCS`s across Nebraska and far northern Kansas. Could
also see diurnal convection develop along any left over outflow
boundaries in the afternoon hours.

&&

.AVIATION...(For the 18Z TAFs through 18Z Tuesday Afternoon)
Issued at 1211 PM CDT MON AUG 25 2014

VFR conditions are again expected through the TAF period with two
potential exceptions. This morning`s rainfall at all TAF sites may
allow for vis restrictions around sunrise if winds become light
overnight. The other potential is for isolated TS to develop again
near all sites between 23Z and 02Z...and possibly again during the
overnight hours. Due to the low probability of these events,
currently have a VFR forecast through the period.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY until 8 PM CDT this evening FOR KSZ010>012-021>024-
026-034>040-054>056-058-059.

&&

$$

SHORT TERM...65
LONG TERM...53
AVIATION...Barjenbruch





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