Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 182101
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
401 PM CDT Fri Apr 18 2014

.SHORT TERM...(This Evening through Saturday)
Issued at 400 PM CDT FRI APR 18 2014

An upper level ridge across the central plains this afternoon will
slowly move east across the mid and lower MS river valley by
Saturday Afternoon. An upper level trough off the southern CA
coast...embedded in the southern branch of the upper level
jet...will lift northeast into NM by late Saturday afternoon. During
the day on Saturday, A lee surface trough will deepen across western
KS as a weak cold front moves southeast into northwest KS. A dryline
will develop across extreme southwestern KS and the OK and TX
Panhandles.

The southerly low-level winds on Saturday will advect deeper
moisture northward from west central TX...north across western OK
into west central and central KS. There may be enough moisture and
surface convergence along the dryline and surface cold front for
scattered showers and thunderstorms to develop during the afternoon
hours of Saturday. At this time the cold front will remain west of
the CWA Saturday afternoon...thus thunderstorms will develop across
west central and the western portions of north central Kansas north
into south central NE.

High and mid level clouds will increase through the day Saturday.
The pressure gradient will increase across central and eastern KS
will increase during the day Saturday, and will cause
south-southeast winds to increase to 20 to 30 MPH with gusts of 30
to 35 MPH during the late morning and afternoon hours.

Minimum RH`s will only decrease to 40 to 45 percent Saturday
afternoon due to the advection of deeper moisture through the
afternoon hours. So the rangeland fire danger may only be in the
high category.

Lows tonight will only drop into the mid 40s to lower 50s. Highs on
Saturday will warm into the upper 70s to lower 80s.


.LONG TERM...(Saturday Night through Friday)
Issued at 400 PM CDT FRI APR 18 2014

Models still show a split mid-level flow across the CONUS Saturday
night into Sunday with the trough currently situated over southern
California expected to progress eastward across the southwestern
U.S. before gradually lifting into the northern stream Sunday and
Sunday night. The forecast area will be wedged between high pressure
to the east and low pressure to the west, with a cold front progged
to stretch from northwest Kansas to south central Nebraska Saturday
night. The best forcing and low-level convergence looks to be
focused just north and west of the area near the front, but cannot
rule out a few scattered showers and thunderstorms skimming across
far north central and far northern Kansas. Shear looks to be very
weak across that area but should have some elevated instability
present through the overnight hours. Have trimmed Saturday night
PoPs back some with low-end chance PoPs near the KS/NE border. This
elevated instability will still be in place into Sunday with better
forcing expected by Sunday night as the southern stream wave lifts
northward across the area to merge with the northern stream. With a
few weak embedded shortwaves moving over the area through the day on
Sunday, there may just be some periods of scattered showers and
thunderstorms with better chances across central Kansas during the
afternoon hours as the main mid-level wave approaches the area. As a
result, split the PoPs for Sunday between the morning and afternoon
to reflect this pattern. Have likely PoPs across much of the area
for Sunday night with this passing wave. MUCAPE values upwards of
1000-1500 J/kg may be present over central Kansas early in the
evening but will quickly diminish through the evening hours with
wind shear remaining very weak, so do not anticipate any severe
weather. The cold front associated with this system will finally
track eastward over the area late Sunday night through Monday
morning with the showers and thunderstorms diminishing from west to
east through the day on Monday. With southerly winds and increased
cloud cover Saturday night, low temperatures should only drop into
the mid/upper 50s. With a warm start and breezy southerly winds,
expect Sunday temperatures to rise into the mid (and possibly even
upper) 70s with lows Sunday night once again in the mid/upper 50s.
There doesn`t look to be much cold air associated with this frontal
passage so highs for Monday should only cool into the low 70s.

Surface high pressure will build in across the central U.S. Monday
night into Tuesday behind this system with a mid-level ridge moving
toward the Rockies. This will keep conditions dry with highs in the
70s once again for Tuesday. This ridge quickly shifts into the
central U.S. Tuesday night into Wednesday as the next mid-level
trough surges into the Pacific northwest. Models are showing a few
weak embedded shortwaves developing the mid-level flow along the
southeastern edge of the trough, which could bring some
precipitation chances to the area on Wednesday. However, soundings
show very dry conditions in the low-levels, up to at least 700mb, so
it may be difficult to get anything to develop. But, with some model
consistency present, still kept low PoPs in the forecast. As this
trough sweeps into the Northern and Central Plains Wednesday night
through Thursday, it will push a cold front through the area.
However, there are still model discrepancies with regards to the
exact timing of this frontal passage and the resultant chance for
precipitation across the forecast area. The ECMWF remains the most
progressive in pushing the front east of the area by Thursday
afternoon, limiting the area of thunderstorm development to Missouri
and possibly far eastern Kansas. The GFS on the other hand has the
front bisecting the area from north to south early Thursday
afternoon, which would be more favorable for thunderstorm
development, especially across eastern Kansas. Have trended more
toward the ECMWF at this time, and went with slight to low-end
chance PoPs for Thursday and Thursday night.

&&

.AVIATION...(For the 18Z TAFs through 18Z Saturday Afternoon)
Issued at 1217 PM CDT FRI APR 18 2014

Expect VFR conditions for the next 24 hours. Southeast winds will
increase to 8 to 12 KTS this afternoon with some gusts. Southerly
winds will increase to 14 to 16 KTS with gusts 23 to 25 KTS by 15Z SAT.


&&

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

$$

SHORT TERM...Gargan
LONG TERM...Hennecke
AVIATION...Gargan





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