Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 211804
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
104 PM CDT Thu Aug 21 2014

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 245 AM CDT THU AUG 21 2014

Thunderstorms again not far from the local area and could skirt the
northwestern counties over the next few hours. This appears the
result of better moisture and moisture convergence via the low level
jet, with with southwest low-mid level flow likely keeping this
focused to the north. Some gustiness in surface winds has been
common overnight due to the stronger jet, helping keep temps in the
upper 70s to lower 80s.

Will keep small mention of precipitation very early in the far north
as decreasing mass flow occurs from the nocturnal jet mixing out
through the mid morning. Models are very similar with 850mb temps
rising another 1-2C with mixing well through this layer bringing
highs up in kind. Dewpoints should remain in the mid 60s to around
70 and bring apparent temps into the 101 to 105 range, but
confidence in the higher levels being widespread or more than brief
is too low for a Heat Advisory. For tonight, the low level jet,
though weaker, looks to be displaced a bit farther southeast, with
deep layer moisture increasing from the southwest. Setup doesn`t
appear as strong as that seen to the northwest this morning, but
small thunder chances seem in order for mainly northern and central
areas.

.LONG TERM...(Friday through Wednesday)
Issued at 245 AM CDT THU AUG 21 2014

Friday and through the weekend the heat continues, as upper ridge
remains solid to the east of the forecast area and noses northward
into the Great Lakes through this period. Shortwave lifts
northeast out of the desert southwest through the western
periphery of the upper high and into the northern plains by early
Sunday, bringing periodic chances for rain along our northern and
western borders. Eastern areas remain capped as influence of upper
ridge prevails. High temperatures may cool along the north if
clouds or rain chances can materialize, but mid to upper 90s
continue in the eastern counties. Heat indicies Friday near
100-105 and come down just a few degrees each day over the
weekend.

GFS and EC both lift leading shortwave trof into the northern
plains by late weekend. While both then lift the larger eastern
lobe of the upper trof into southern Canada, the EC is then deeper
and stronger with the next piece of energy to move into the back
side of the longwave trof over the Pacific Northwest. The GFS is
weaker and more progressive, and swings the trof across the plains
by the end of the forecast period Wednesday. The EC retrogrades
the energy, which boosts the upper high back northward into the
Central Plains. Mondays forecast would be influenced by how far
south the surface front can be pushed before southwesterly flow
aloft aids in pushing the front back northward. Unfortunately both
solutions would suggest even if Monday brings a cooler shot and a
chance for precipitation, that this push on Tuesday would make
short work of bringing the warm temperatures back north for
Tuesday. Progressive GFS would bring front through on Wednesday
while the EC holds in the heat another day. Later periods in the
forecast certainly reflect probabilistic chances for precipitation
and generally focus chances on the west and north where
perturbations in the flow have greater chances for influence.

&&

.AVIATION...(For the 18Z TAFs through 18Z Friday Afternoon)
Issued at 102 PM CDT THU AUG 21 2014

VFR conditions are likely through the TAF period. Will be
monitoring a weak front in north central KS as it may develop a few
thunderstorms with a small chance of impacting MHK...mainly
between 02Z and 07Z. TS seems unlikely at this point though.

&&

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

$$

SHORT TERM...65
LONG TERM...67
AVIATION...Barjenbruch






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