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

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FXUS63 KEAX 232118

418 PM CDT Wed Jul 23 2014

.SHORT TERM...(This Evening through Saturday Night)
Issued at 416 PM CDT WED JUL 23 2014

Broad area of high pressure extending from south central Canada
through the Mid MS and Mid MO River Valleys will maintain a steady
flow of below average temperatures and humidity levels for one more
day. Will likely see another convective complex form over SD and/or
NE tonight with NNW flow steering the activity towards northwest MO.
Best isentropic ascent on the 310K surface remains just north of the
CWA tomorrow and models have even trended further north. Seems
reasonable and have lowered/scaled back PoPs over northern MO.

Thursday night-Saturday night:
Large upper high centered over the Central Rockies will retrograde
some while its ridge axis extending through MT shifts east and
flattens in response to a strong/compact upper low tracking east
across southern Canada. At the surface high pressure over the Great
Lakes and OH Valleys retreats east. This will allow surface pressure
falls to occur across the Central/Southern Plains and allow a warm
front to lift northeast and through the CWA on Friday. Models have
been fairly consistent with this theme over the past several runs.
Increasing warm air advection/isentropic ascent should generate
elevated convection north of the warm front late Thursday and early
Friday with best chances for precipitation over the northeast 1/3 of
the CWA.

Expect the extreme heat and humidity we saw on Tuesday to return for
Friday and Saturday with heat indices over 100 a foregone conclusion.
Headlines will be needed eventually for this period. Also expecting
to see a pronounced elevated mixed layer with h7 temperatures of
+14C to spread back across KS/MO and effectively cap off any
convection until late Saturday afternoon or evening. By then a cold
front is expected to arrive form the northwest and increase the
threat for convection. Have sided with the more northern frontal
position of the GFS/ECMWF which have performed better than the NAM
past day 3. Moderate to extreme instability with modest 0-6km shear
of 30kt suggest severe storms may be possible near the front.

.LONG TERM...(Sunday through Wednesday)
Issued at 416 PM CDT WED JUL 23 2014

Major pattern change expected during this period with a very
amplified western ridge and eastern trough pattern. There is good
run-to-run continuity and model agreement on this scenario unfolding
so overall confidence is well above average. Mid level height
anomalies in excess of 2 standard deviations below normal over the
eastern U.S. sets us up for much below average temperatures on par
with what we experienced July 14-18. Model runs are trending cooler
than previous runs and have latched onto this idea by lowering
temperatures next Monday-Wednesday. Dry and very pleasant for late


.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 1237 PM CDT WED JUL 23 2014

VFR conditions will continue.

Convective complexes moving through NE and KS will pass well to the
west of the terminals. Could very well see another convective complex
or two form over SD and/or NE late tonight with the north-
northwesterly flow aloft steering them towards northwest MO Thursday
morning. The precipitation should remain north of the terminals,
possibly reaching far northwest MO, with only high level convective
cloud debris spreading across western MO/eastern KS Thursday morning.




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