000
FXUS63 KTOP 221138
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
638 AM CDT Tue Apr 22 2014

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 324 AM CDT TUE APR 22 2014

Surface high pressure ridge extending southward across the county
warning area (CWA) through early afternoon will gradually shift
east of the area by evening. The result will be fairly light
northeast breezes this morning becoming more east and southeast in
the afternoon. Wind speeds will also increase over the north
central from the southeast in the afternoon. Warmer temps aloft
and stronger mixing in the north central counties will support
highs in the middle 70s...with readings closer to the 70 degree
mark over the eastern counties. Although thin high clouds will
gradually increase west to east later in the day...a mostly sunny
sky will be the rule.

Tonight...the next shortwave trough over the western U.S. will begin
to approach the central high this evening which will aid the
strengthening of the nocturnal low level jet. Modified gulf moisture
return from the southern high plains will begin to advect
north/northeastward overnight into the far western counties of the
CWA. This will result in some weak elevated instability above 10 KFT
so have opted to leave in some low pops for convection after
09z...but not expecting coverage or intensity to be any more than
isolated and weak and primarily confined to the northwest 1/2 of the
the CWA. With increasing clouds/winds and sfc dewpoints over the
western counties overnight...increased lows slightly into the mid
50s with the cooler readings in the upper 40s over the far eastern
counties.

.LONG TERM...(Wednesday through Monday)
Issued at 324 AM CDT TUE APR 22 2014

Wednesday and Wednesday night, models are in pretty good agreement
with a shortwave trough moving from the inter-mountain west into
the northern and central plains. There has been good consistency
in models showing high based storms lingering into Wednesday
morning. Elevated instability appears to be pretty limited so do
not anticipate much more than a couple showers and thunderstorms.
However thunderstorm development during the late afternoon along
the dryline/cold front continues to show the potential for strong
to severe storms. As mentioned in the SWODY2 outlook, moisture
return is less than outstanding, but shear parameters look
favorable for organized convection. 0-1km and 0-3km bulk shear
ahead of the boundary is high with models forecasting a 60 to 70kt
low level jet nosing into the forecast area. So even if storms
evolve into a squall line, the magnitude of low level shear and
helicity suggests there may be a low end tornado threat with the
storms Wednesday evening with any embedded circulations along the
line of storms. In addition to the chances for thunderstorms,
Wednesday looks to be windy as the pressure gradient strengthens
ahead of the surface trough. Southerly winds gusting to around 40
mph could flirt with wind advisory. Deep mixing of the boundary
layer and modest warm air advection should help push highs into
the upper 70s and around 80.

Thursday could end up being an day to watch out for fire weather
as the precip exits to the east. The NAM and GFS show deep mixing
of the boundary layer with unidirectional westerly winds becoming
gusty in the 20 to 25 mph range through the afternoon. With dry
air moving in from the west, afternoon RH values could fall to 20
percent in the afternoon and any critical fuels that haven`t
started to green up could pose a risk. highs are expected to warm
into the lower 70s due to the deep mixing near 700 MB and
afternoon insolation.

Unsettled weather for the weekend and early next week continue to
look likely with the models still wanting to develop a cutoff low
somewhere over the plains. There remains differences in the small
scale details, but in general think a boundary will slide into the
forecast area late Friday night. This may lead to an over running
set up for a period of time as southerly 850 winds keep bringing
moisture north. Given the uncertainty in the deterministic
solutions and the overall trend of the synoptic patter becoming
less progressive, have chance POPs in the forecast for Saturday
through Monday. The ECMWF and GFS do not bring a surface low out
across the plains until Monday. This looks like the most likely
time cooler air will start to spill south into the forecast area.
Until then, the location of the surface boundary will have a large
impact on temperatures and the forecast shows a good gradient
across the forecast area with 60s north to 70s south both Saturday
and Sunday.

&&

.AVIATION...(For the 12Z TAFs through 12Z Wednesday Morning)
Issued at 631 AM CDT TUE APR 22 2014

VFR conditions will persist across the terminals through the fcst period.
light east to northeast winds will become southeast towards 21Z
and increase to around 10 kts. Only sct-bkn mid and high clouds
through the fcst period. The potential for convection at any of the TAF
sites thru 12z/23 remains too low to insert into any of the
terminal fcsts at this time.

&&

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

$$

SHORT TERM...63
LONG TERM...Wolters
AVIATION...63