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Area forecast discussion 
National Weather Service Topeka Kansas
626 PM CDT Thu Apr 24 2014

..update to aviation forecast discussion...

Short term...(this evening through friday)
issued at 230 PM CDT Thursday Apr 24 2014

Mid level shortwave is passing over the forecast area this
afternoon which has placed the large scale lift eastward over MO.
An area of elevated showers has developed along the trough axis in
central Kansas but low level dry air moving in from the northwest is
preventing most of the precip from reaching the ground. Clouds
will also be on the decrease this evening with the clearing line
moving from west to east. High temperatures this afternoon will
likely be cooler than previously expected. Winds will diminish
after sunset as high pressure builds into eastern Kansas. Light winds
and mostly clear skies will allow for low temperatures in the low
to mid 40s. Some low lying areas could develop fog or haze early
tomorrow morning but widespread dense fog is not expected.
Tomorrow winds will pick up out of the southwest as the next
system approaches and a Lee side trough forms in the High Plains.
These winds are expected to stay below advisory criteria. Mostly
clear skies prevail and high temperatures reach the upper 70s to
low 80s.

Long term...(friday night through thursday)
issued at 230 PM CDT Thursday Apr 24 2014

Severe weather potential for Saturday into Sunday is primary
forecast concern.

Friday night...brings a return to warm air advection with most
models bringing a round of showers and thunderstorms across the
northeast counties toward 12z on the nose of the low level jet.
NAM soundings suggest around 500-700 j/kg to work with so not
anticipating severe for the early morning hours. Overnight lows
expected to hold in the middle 50s most areas. Deep southerly flow
also brings a return flow off the Gulf and 60 degree dewpoints
back into Oklahoma by 12z and across eastern Kansas around 18z per
NAM with the GFS just a bit slower.

Saturday...dryline sets up across western Kansas with the NAM
slightly farther eastward, and instability pooling along the
boundary generally around 3200j/kg by 0z Sunday. Also has been
consistency in sending what appears to be a dryline surge eastward
across the Kansas/NE border by this time, perhaps as the result of a
shortwave moving over that area. Appears there is also a 500mb jet
streak moving over the dryline over central and south central
Kansas, and another weak shortwave. If these factors are enough
to initiate storms along the dryline, they will have the potential
to propagate eastward into central and north central Kansas in the
evening hours. Shear and instability diminish toward the east, and
cap strength continues to build in the warm sector as well, so
some uncertainty as to how far eastward these storms could
propagate in the absence of a strong lifting mechanism and with
strengthening cap to the east. At this time best chances for
storms are 0-6z. With storm motion off the dryline these storms
will have the ability to remain isolated, and produce all forms of
severe weather, including tornadoes if they can tap into the lower
local heights to the east of the dryline.

Sunday...dryline retreats back toward the west by the early
morning hours, before the upper low then moves into southeast
Colorado by 12z Sunday. As the base of the wave swings eastward
into central Kansas, wind along the dryline/front aligns itself
nearly parallel to the boundary. This will make for complications
in storm Mode as the whole system moves eastward through Sunday
late morning and into the afternoon. Axis of cape values around
2000j/kg remain just along the leading edge of the boundary. At
this time think most likely will see a line of storms move
eastward across the area, then stall over the eastern counties
late in the day Sunday. Wind would be primary concern, with hail a
secondary threat. Not sure if there will be enough turning in the
column for qlcs in the line, but will monitor forecast evolution
for the potential. Of other concern is individual storms in the
line developing and training to the north over the same areas, and
with precipitable water values at 1-1.5 inches will have to watch for locally
heavy rainfall. System stalls out as base of the wave gets slowed
by secondary piece of energy rotating into it from the northwest.
This could continue a strong to severe threat well into the
overnight hours for the far east counties.

Monday...a mid-latitude cyclone becomes the major meteorological
player in our County Warning Area for the next few days. Left over convection from
Sunday will begin to move out. At this time, the European model (ecmwf) is
resolving good instability with cape values ~1500 j/kg into
Monday, so additional strong convection cannot be ruled out. A
cold front associated with the mid-latitude cyclone should be the
primary forcing mechanism present. Storms could be severe.

Tuesday and Wednesday...the mid-latitude cyclone will translate to
the east, but conditions should remain miserable as the wrap-
around moisture from the low pressure center should affect our
region. By this time, winds will have veered to the northwest
bringing very gusty winds and cooler temperatures. Winds could
gust up to 30kts by Tuesday afternoon. Low temperatures should
trend cooler after the cold frontal passage, with temps around
40f. Precipitation should move out by late Thursday.


Aviation...(for the 00z tafs through 00z Friday evening)
issued at 626 PM CDT Thursday Apr 24 2014

VFR conditions expected for most if not all of the period. Clouds
exiting between 00z and 01z at top and foe. Winds will become
light after 01z-02z and with clear skies could see some light
mist/fog developing at top and mhk, but winds in lower boundary
layer may remain mixed enough for no fog to form. Will hold off
including for now and revisit at the 06z issuance.


Top watches/warnings/advisories...


Short term...Sanders
long term...67/js