Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 060452
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1152 PM CDT Sat Jul 5 2014

...Updated for 06Z Aviation Forecast...

.UPDATE...
Issued at 950 PM CDT SAT JUL 5 2014

Short term models (HRRR, RAP13) continue to try to develop
convection over eastern Kansas this evening, and it continues to
not develop to this point. New NAM not as aggressive as previous
two runs, but still has spotty precip and more persistent precip
in east central KS through tonight. Water vapor imagery showing
one mid- level shortwave trough move southeastward across central
and eastern KS, and weak subsidence behind it may be helping to
suppress evening convection in KS. Models do have postive theta-e
advection in the 850 to 700 mb layer for later this evening
through 1 AM, so have not removed POPs from eastern KS, but have
dropped them for north central KS for tonight. Any thunderstorms
that do form will obviously have the potential for heavy rain with
precipitable water values near 2" and decent moisture transport
evident at 850 mb.

&&

.SHORT TERM...(This Evening through Sunday)
Issued at 244 PM CDT SAT JUL 5 2014

Forecast today quickly challenged with mesoscale conditions as
convective complex moved across eastern Nebraska in the early
morning hours. An outflow boundary then moved southwest into
northeast Kansas, through about Topeka to just east of Marysville.
As southwesterly surface winds have strengthened through the day,
they have worked to counter slightly reinforced outflow and push
this boundary back to the north. Little progress was made on the
east end, and appears as though the incoming upper shortwave
evident on WV imagery will move across this boundary for the
remainder of the afternoon and evening hours.

While shear is not ideal, and high surface dewpoints not conducive
for a high end wind threat, there is enough instability
(2000-3000J/kg range) to consider hail and possibly locally heavy
rainfall a threat if these storms develop and move through.
Forecast is certainly probabilistic - GFS confines convection more
east, as does the EC, although the EC is slower with its exit
through the morning on Sunday.  The HRRR and NAM extend area of
convection farther westward from NE KS and drop cluster of precip
south southeast across the area through the evening hours. Have
played the forecast toward the latter, although kept coverage
isolated in nature as it passes through.  Can`t rule out a bust with
precip, especially as you go west, but do think the far eastern
counties will see hit and miss showers and thunderstorms as the
evening goes on.

Heat returns on Sunday as mid level temperatures climb under the
shortwave ridge behind the departing shortwave trof.  Have highs in
the 90s with heat indices coming out in the 99-103 range as the
dewpoints hold around 70 east to the 60s west...however western
counties are hotter so in the end heat index differences are subtle
at best.

.LONG TERM...(Sunday Night through Saturday)
Issued at 244 PM CDT SAT JUL 5 2014

By Sunday evening the cold front dips southward from central NE,
straddling the KS and NE border near 00Z. The main upper trough
positioned to our north and east at this time has given guidance
lower confidence in precip developing near the weakly convergent
frontal boundary until after midnight. Northern areas of the CWA
have a slight chance for thunderstorms while most of the CWA
remains dry.

Monday afternoon will be another hot and humid day as the surface
trough over western KS deepens, increasing southwesterly flow and
mixing of warmer air aloft. Highs once again in the mid to upper 90s
are likely with heat indices between 100 and 103 degrees. A more
potent shortwave trough digs southward through the plains on Monday
evening, shunting the cold front through the CWA by 18Z Tuesday.
Showers and thunderstorms are likely across the Nebraska and
northwest MO border, decreasing to a chance further south as the
heavier precip bands follow the upper trough axis centered over
central/northern MO. Wind shear through 6 KM increases overnight
with the passing wave between 30 and 40 kts while MLCAPE is around
1500 J/KG. A few stronger storms cannot be ruled out, especially if
they redevelop or are able to become sfc based in the afternoon.

Winds shift back towards the south with another incoming upper wave
expected Wednesday evening. Trends show the heavier precip bands to
impact mainly north central and portions of central KS where highest
pops were placed. Precipitation will wane as it lifts northeast
through Thursday, replaced by temporary ridging on Friday. Saturday
begins the unsettled pattern once again as northwest flow begins
to bring another series of weak disturbances through the region.

Highs behind the boundary Tuesday through Thursday will cool back to
the 80s with lows in the upper 60s. Increased warm advection Friday
and Saturday, raise temps once again to the 90s accompanied by lows
in the 70s.

&&

.AVIATION...(For the 06Z TAFs through 06Z Sunday Night)
Issued at 1148 PM CDT SAT JUL 5 2014

Expect VFR conditions through Sunday. With high pressure over Gulf
Coast and low pressure over western KS, expect southerly flow to
continue. Winds on Sunday should be weaker/less gusty than those
on Saturday. Cannot completely rule out an isolated thunderstorm
in eastern KS the rest of tonight, but confidence is low and
chances of occurring at FOE or TOP also low. Thus, have not added
to TAF.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...GDP
SHORT TERM...67
LONG TERM...Bowen
AVIATION...GDP






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