000
FXUS63 KTOP 311158 AAA
AFDTOP

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TOPEKA KS
558 AM CST Sat Jan 31 2015

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 330 AM CST SAT JAN 31 2015

Radar and surface obs showing light rain occurring across most of
the county warning area (cwa) at 3 am...with some snow mixing in at
the surface to the west. Freeze levels across the southeast half of
the cwa should remain the highest...with lower freeze levels to the
northwest through mid morning before rising there as well. Will keep
a mention of the possible mixture until mid morning north and west
of Herington to Hiawatha line. As the initial shortwave over the
central high plains lifts out...will carry categorical light rain
all areas through the remainder of the day as warmer air in the low
levels will be well established all areas through the afternoon.
Still...with total cloud cover and frequent periods of light rain
and dewpoints in the 30s...not expecting much of a rise in temps
today...from the middle 30s near the Nebraska border to the
lower 40s along and south of I 70.

As the first wave lifts eastward across the area this evening and
the upstream trough approaches from the northwest the southward
advance of the colder air from Nebraska back into the far northern
cwa appears delayed until no early than mid evening in the far
north/northwest portions of the cwa. Will introduce a mixture of
rain and snow again...then snow likely after midnight. Further
south...will not introduce a mix along I 70 corridor until after
midnight and an all snow potential here until after 09z. Any mix in
the far east central looks to be after 3 am. In summary...as the
colder air necessary for an all snow changeover arrives...the forcing
is on the decline and sfc temps are also at or slightly above
freezing at the time of a complete changeover. This is especially the
case across the southern half of the cwa...with much colder temps
overnight to the north. This will result in the highest
accumulations through 6 am (near an inch closer to the Nebraska
border...steadily decreasing southward to little or none south and
east of the Turnpike.

.LONG TERM...(Sunday through Friday)
Issued at 330 AM CST SAT JAN 31 2015

Sunday, An upper level trough will be moving east across NE and KS
into IA and MO. Strong low-level CAA will change any rain or
rain-mixed with snow over to snow across east central KS during the
mid morning hours. The northeast counties will continue with light
snow through most of the morning hours with an additional half inch
of snow possible across Nemaha, Brown and Jackson counties.
The light snow will diminish to snow showers or flurries across the
extreme eastern counties after 12 noon.

As the upper trough amplifies across IA and MO the surface/850mb low
will deepen across the mid MS river valley. The stronger pressure
gradient across eastern KS will cause north winds to increase to 20
to 30 MPH with gusts to 45 MPH during the mid and late morning hours
and continue through the afternoon. A wind advisory may be needed
for the CWA on Sunday, especially if the next model runs come in
more amplified. The strong low-level CAA will cause high
temperatures to occur across the CWA during the mid morning hours
with temperatures falling through the day through the 20s into the
teens.

Sunday night and Monday, a surface ridge of high pressure will build
southeast across the central and southern plains. The northwest winds
will diminish through the evening hours. Clear skies and light winds
will allow overnight lows to drop into the single digits across the
northern half of the CWA with lower teens across the southern
counties. Light winds will become southerly as the surface ridge
shifts southeast across the mid and lower MS river valley. Highs
will continue to be cold in the upper 20s northeast to mid 30s
southwest.

Monday Night and Tuesday, The upper flow will become slightly more
zonal, thus a lee surface trough will deepen across western NE and
eastern CO. The surface trough will shift east through the day and
southwesterly winds ahead of the surface trough will warm
temperatures back into the lower to mid 50s across much of the CWA.
The northeast counties may only see highs in the mid 40s.

Tuesday night through Thursday, An upper level trough across central
Canada will dig southeast across the northern plains into the
Midwest and Great Lakes States. This will cause another surge of
cold air to move southward across Kansas. Highs on Wednesday may
occur in the morning with temperatures falling through the 30s into
the 20s through the day. North winds of 15 to 25 MPH will make it
even feel colder. There may be a chance for snow showers or flurries
Tuesday night and Wednesday. Lows Wednesday night will drop into the
single digits and teens as the center of a surface ridge builds
southeast across eastern KS. During the day on Thursday the surface
ridge will shift east-southeast into the mid and lower MS river
valley. Surface winds will become southerly by Thursday Afternoon.
High temperatures on Thursday will only reach the mid 20s to lower
30s.

Thursday night through Friday, an upper level ridge across the
southwestern US will slowly build east across the southern high
plains. Highs will warm into the lower to mid 40s by Friday Afternoon.

&&

.AVIATION...(For the 12Z TAFs through 12Z Sunday Morning)
Issued at 552 AM CST SAT JAN 31 2015

Mvfr cigs 1500-2500 feet and vsbys 3-5sm in rain at KTOP/KFOE will
be the rule through 00Z before lowering to IFR in rain and snow
beyond 00z. MVFR conditons in rain at KMHK will lower to IFR aft
17z then LIFR aft 08z in rain and snow.

&&

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

$$

SHORT TERM...63
LONG TERM...Gargan
AVIATION...63