Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 161132

632 AM CDT Thu Apr 16 2015

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 314 AM CDT THU APR 16 2015

Current water vapor imagery shows the main mid/upper low spinning
over the four corners region. It also shows smaller scale shortwaves
and speed maxes progressing through the SW flow aloft out over the
plains. One moving over the high plains this morning tracks
northward along with the ongoing convection in SW NE that appears to
be focused on the nose of the low level jet. The low level jet is
forecast to veer over central KS later this morning and weaken in
the process. Some of the models are suggesting isentropic lift with
elevated instability could support scattered showers and
thunderstorms in central and northern KS through the daytime hours.
Forecast soundings show that better moisture as well as steeper
lapse rates will continue to spread northward ahead of the main low
especially western and central KS. Low level moisture remains across
NE KS through most of the morning and is forecast to mix with
slightly drier air aloft and scatter out. Expect the low stratus and
some fog will stick around until daytime mixing can intensify. The
main uncertainty today will be the coverage of showers and
thunderstorms during the day. Not sure how far east the precip will
spread, so the better chances remain across NC KS. This is where low
level convergence is maximized and instability is forecast to
increase. Although the deep layer shear is relatively weak, so do
not expect much in the way of any organized convection. Small hail
would be the main threat and possibly some gusty winds. The other
concern will be how much clouds clear out later today and how far
west, which could affect the temps and mixing. As of now high temps
are forecast to reach the low to mid 70`s. Tonight the mid/upper low
creeps eastward and so does the low level jet. Storms should develop
in western KS this evening and move into central KS overnight. How
far east the storms progress is uncertain since the better forcing
and low level jet focus more over central KS.

.LONG TERM...(Friday through Wednesday)
Issued at 314 AM CDT THU APR 16 2015

A cut-off amplified upper low over northern NM early Friday morning
will slowly drift east-northeast into southeast CO by Saturday
afternoon. An upper level trough embedded in the northern stream of
the mid and upper level jet will move east across western Canada
into the northern high plains by 00 SUN. The northern stream H5
trough will begin to phase with the closed upper low across
southeast CO as it moves east into the northern high plains. Both
upper troughs will move across the plains on Sunday and into the
Midwest and MS river valley by Monday, where further amplification
will occur. The amplified upper low will slowly track east across
the northern Great Lakes, this will keep the plains in northwesterly
flow at mid and upper levels from Monday through the middle of
next week.

Friday, thunderstorms that developed along the dryline and warm
front from western KS southward through the TX PNHDL Thursday
afternoon and evening may form into one or two complexes of
thunderstorms that will move north-northeast across the western half
of the CWA during the morning hours. Both the NAM and ARW show that
the morning storm may stabilize the environment and MLCAPES through
the afternoon may only recover to 500 to 1000 J/JKG. The best
destabilization may occur across west-central KS where insolation
may occur. The upper low will continue across southeast CO and the
main mid level jet max will curve cyclonically northward across west
TX into western KS. The mid level flow looks fairly weak across the
CWA with only 20 KTS of south-southwesterly 500mb winds Friday
Afternoon. If thunderstorms develop across the area the sfc to 6KM
effective shear will only be 20 to 30 KTS. I`m not expecting the
environment to support severe thunderstorms on Friday due to weak
vertical wind shear and marginal instability. However, a few storms
may pulse up and produce gusty winds and small hail. If more
insolation occurs Friday afternoon, then MLCAPES may be higher than
what the NAM is forecasting, and perhaps there will be a better
chance for pulse severe storms. Friday`s highs will be dependent on
the amount of insolation we will see. The better chance for at least
partly cloudy skies will be across the eastern counties of the CWA
where Highs will reach the lower to mid 70s. The western counties
may only see upper 60s to lower 70s.

Friday night, storms that develop along the dryline Friday afternoon
and evening across western OK and southwest KS will move northeast
across the area. MUCAPES will only be around 500 J/KG, thus any
thunderstorms will not be severe.

Saturday and Saturday night, After the showers and thunderstorms
during the morning hours shift northeast, the cloud cover will break
up across west central KS. A surface dryline will push east into
central KS. If we see enough insolation, MLCAPES will increase to
around 2,000 J/kg and the vertical winds shear will increase as the
upper low across southeast CO begins to lift east-northeast across
western KS. Strong to possibly severe thunderstorms will develop
across central and north central KS Saturday afternoon and push
northeast across the remainder of the CWA during the late afternoon
and evening hours. The NAM model never builds the instability east
across northeast and east central KS. Therefore, any strong to
severe thunderstorms across north central and central KS that push
northeast across the remainder of the CWA may weaken through the
evening hours.

Sunday, the southern stream upper low will begin to fill as it lifts
east-northeast across KS. A surface cold front will push southeast
across the CWA during the morning hours. There looks be enough
ascent ahead of the H5 trough combined with isentropic lift north of
the boundary to produce widespread showers and isolated
thunderstorms through the day. High temperatures may occur in the
late morning and early afternoon hours with steady or slowly
falling temperatures as stronger low-level CAA develops behind the
front. Northwest winds of 15 to 25 MPH with gusts to 35 MPH will
make it feel even colder during the afternoon hours.

Sunday night, The showers should rapidly end from west to east
across the CWA as the phased upper level trough moves east into the
upper Midwest and MS river valley.

Monday through Wednesday, northwest flow at mid and upper levels
will continue across the plains as the the amplified upper low over
the upper Midwest slowly shifts east into the northern Great lakes.
Highs will only reach into the 60s. Clear skies and light winds
Monday night will allow low temperatures to drop into the mid to
upper 30s across much of the CWA. Frost may be possible by sunrise
on Tuesday across much of the western and northern counties of the
CWA. Some areas may get close to freezing.


.AVIATION...(For the 12Z TAFs through 12Z Friday Morning)
Issued at 627 AM CDT THU APR 16 2015

MVFR/IFR conditions should improve through out the morning hours.
Expecting VFR conditions by the early afternoon rather it be
through lifting of the ceilings or scattering out of current cloud
cover. Later tonight storms are forecast to develop over central
KS and move eastward. Have low confidence on how far eastward the
storm coverage will be, so have MHK with VCTS for now.




SHORT TERM...Sanders
LONG TERM...Gargan
AVIATION...Sanders is the U.S. government's official web portal to all federal, state and local government web resources and services.