Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO

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FXUS63 KEAX 222033

333 PM CDT Tue Jul 22 2014

Issued at 333 PM CDT TUE JUL 22 2014

Mid to upper 90s prevailing across much of the region this afternoon
as the warmest airmass of the season continues to grip the area.
Latest 850-mb analysis from the SPC meso site showing the 28C temp
contour directly over the fcst region this afternoon. This combined
with steep low-level lapse rates and dewpoints largely in the lower
to middle 70s has resulted in a very hot and oppressive day across
the area. Current heat advisory for the entire fcst area needs no
adjustments and is set to expire at 7 PM this evening.

In addition to the heat...the other main concern remains focused on
possible severe convection later this evening as main cold front now
found over southwestern IA and eastern NE continues to slowly track
south with time. For what its worth...high-res convection allowing
models struggled mightily with this mornings convection across
our northeastern zones...and very little guidance from these models
appears to be in the offering for activity later this evening as
well. Not surprisingly...overall confidence for tonight/s fcst is
less than desired as some models show developing convection...while
others such as the HRRR continue to backtrack towards a drier and
drier fcst with each successive run. So here/s what we know so far...

Sfc boundary set to arrive towards the IA/MO state line around 00z
this evening. Out ahead of this feature...airmass remains capped with
a significant amount of inhibition thanks that 700-mb temps ranging
in the 12-14C range. Additionally...northerly 925-850-mb winds will
provide little if any low-level convergence into the arriving
frontal boundary as we continue into the evening hrs. Despite
this...quick look at latest water vapor imagery does show an inbound
shortwave trough now seen over south-central NE and north-central
KS. This feature combined with very modest frontal convergence may be
enough to get this going...however concerns for widespread severe
remain marginal as of this writing. Latest SPC day 1 outlook has
trimmed the SLGT risk mention further to the southeast...which is
more in line with where convection may develop as front continues to
drop south. That said...main severe threat with any activity that
forms will likely be strong wind gusts as nearly dry adiabatic lapse
rates will support favorable low-level and boundary layer mixing.
High wet-bulb zero heights (>16 kft) will likely negate the threat
for very large hail until later on when any lingering activity begins
to go elevated with due to loss of daytime heating. Overall concerns
for hail though remain the lowest of the two forms of severe outlined
above however. In general...severe threat this evening looks to be
isolated with the most likely areas to possibly see a rogue storm or
two residing in our northeastern zones where better potential exists
to break the cap thanks to slightly cooler temps aloft. If activity gets
going...severe threat should transition south of the I-70 corridor as
front continues to make progress through the area. As mentioned above
through...a widespread severe event does not look to be in the
offering this evening.

Region should largely reside in a post frontal airmass
tomorrow...with weak dry air advection allowing for cooler and less
humid conditions. In fact...fcst models suggest dewpoints anywhere
between 5-10 degrees cooler than today...which should be a welcomed
relief following today/s oppressive conditions. High temps should
round out in the middle to upper 80s.

Large scale pattern shift expected from Thursday into Friday as southern
Plains ridge retrograde west as northern stream energy traverses the
northern Rockies/Plains. As this occurs...upper flow will become
decidedly more northwesterly which will set the stage for unsettled
conditions heading into the upcoming weekend. Closer to the
surface...fcst models still paint a northward retreating warm front
by late week as return flow reestablishes itself across the Great
Plains in advance of leeside troughing along the Front Range. Several
upper shortwaves embedded in northwest flow will allow for continued
chances for showers and storms through at least Saturday...if not
Sunday. As is the case with convection this time of year...hard to
pin your hat on any one feature of interest as long range models to
include both the ECMWF and GFS normally suffer from convective
feedback issues to some degree. As a result...have maintained Chc
pops through the weekend before high pressure arrives by early next
week following the passage of a cold front on Sunday. Temps early
next week look to fall below normal with highs possibly only reaching
into the lower to middle 80s come Monday and Tuesday.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1244 PM CDT TUE JUL 22 2014

Main concern heading into the fcst period remains focused on
convection as weak cold front sinks south across the area. Latest
model trends show the best potential east of all terminal sites but
given the amount of uncertainty with the fcst...VCTS mention was
maintained for all locations after 00z this evening. After 6z...any
convection that does form should be south with weak northeast flow
expected through the remainder of the overnight. Some potential for
developing VSBY restrictions at STJ after 09z as front fails to scour
out abundant low-level moisture.


KS...HEAT ADVISORY until 7 PM CDT this evening FOR KSZ025-057-060-

MO...HEAT ADVISORY until 7 PM CDT this evening FOR MOZ001>008-011>017-



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