Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 221737
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1237 PM CDT Wed Apr 22 2015

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 247 AM CDT WED APR 22 2015

Northwest flow continues to dominate the Central Plains with upper
low still over the Great Lakes and cutoff low south of ridge in the
western states. A stronger wave was rotating around the southern edge
of the low and brought a cold front through all but southeastern
corner of Kansas as of 08Z. Some mid level moisture remains with
isentropic upglide around 300K allowing a few sprinkles to fall in
eastern Kansas.

Models are consistent in this enhanced lift weakening this morning,
though some shallow moisture remains around 600mb. Surface ridge
knifing into eastern Kansas leads to light east winds and combine
with 850mb temps around 8C cooler than Tuesday for highs in the mid
50s to around 60. Some increase in mid cloud is anticipated tonight
as the upper ridge pushes into the High Plains, but forcing is
lacking for precip potential. Models do vary considerably in how far
northeast this cloud will reach, and with light winds this will
likely be key in how far temps fall with SREF T spreads rather large
for the second period. Temps on the west side of the ridge have
reached the upper 20s to lower 30s, so feel fairly confident in mid
30 lows as the bottom end for northeast locations given some
modification and slightly stronger low level wind fields. Will leave
any mention of frost out at this point but at least minor potential
exists the farther northeast one gets.

.LONG TERM...(Thursday through Tuesday)
Issued at 247 AM CDT WED APR 22 2015

For Thursday the area remains between systems, with cooler high
pressure sliding east and south and a mid level ridge over the
state. Highs in the 60s followed by lows in the upper 40s near 50.
Start to see the influence of the low level jet late Thursday
night, with a slight chance becoming a chance for a thunderstorm
toward sunrise on Friday.

Potential for severe weather makes its return on Friday afternoon
into Friday evening. There are still some model differences in
amount of instability that makes it back northeast over the
forecast area, and how far northward the warm sector makes it into
northeast Kansas. With advancing shortwave trof comes around 40-60
kts of 0-6km bulk shear however, and even in a low cape
environment would be favorable for low topped supercells and
severe weather. Cells could also remain severe as they develop
and are lifted northeast over the front for a county or so. It
will remain to be seen how the mesoscale is influenced by
potential morning and early afternoon convection, how far north
the warm sector ends up migrating through the day, the amount of
insolation, and the track of the surface low and the triple point.
At this time have likely PoPs for Friday and Friday night with
best chances late afternoon through the midnight hour.

Northwesterly winds behind the departing trof move through most of
the area by sunrise Saturday, with some wrap around showers still
possible in the colder air. Highs are forecast in the 60s, but
these will likely occur early and fall as the colder air moves in.
Mostly a dry forecast for the following Sunday with highs again in
the 60s, and may see late day showers return west as the next
shortwave approaches. This next incoming system is driven across
Kansas in the GFS and across Texas and Oklahoma in the EC, and
would bode for considerable differences in precipitation
potential. Forecast is a blended probability. Both solutions clear
out by later Tuesday. Sensible temperature forecast remains
similar as previous days with highs in the 60s and lows in the
40s.

&&

.AVIATION...(For the 18Z TAFs through 18Z Thursday Afternoon)
Issued at 1230 PM CDT WED APR 22 2015

VFR conditions will still be the result of high pressure influence
over the region through tomorrow noon. Winds shift to the
East/southeast by the end of the period. Some showers may develop
West of KMHK but should remain there this period. The biggest impact
will be scattered to possibly broken mid to high clouds.

&&

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

$$

SHORT TERM...65
LONG TERM...67
AVIATION...Drake






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