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000
FXUS63 KTOP 251801
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
101 PM CDT WED MAY 25 2016

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 415 AM CDT WED MAY 25 2016

At 4 AM Wednesday morning, a large thunderstorm complex continued to
progress east out of the area. A well-developed MCV was present in
northern parts of this storm complex over far SE Nebraska while a
wake low has developed on the back side. This wake low has been
producing gusts up to 50 mph and will continue to do so as it moves
east although it would seem likely to be near its peak intensity
right now. Additional convective showers and storms were developing
in the convergence zone into east central KS, but this area has been
well worked over and do not anticipate anything more than a few
pockets of heavy rain in this area. Another area of thunderstorms
has been persistently developing in association with the LLJ near
the KS/NE border in north central KS. This area of development is
likely to gradually push a weak cold pool a bit south with
development progressively into northern and northeast KS. However,
it will also be making its way into an area of lesser instability
with the effective convective overturning from early this morning,
and expect the storm development to be sub-severe and any associated
outflow likely not very strong.

As the day goes on, the forecast will once again be complex but
there are at least a few moderate confidence elements to grasp on to
in making the forecast. The first is the outflow incoming from the
north which should set up east to west across the area and then wash
out by mid to late afternoon...although some semblance of it may
remain through late day. The second feature of interest has been
consistently forecast by models over the past few days, and that is a
slightly veered flow owing to the passage of a rather strong short
wave early this morning. This veered flow will cause the dryline to
surge east with a dryline bulge into eastern KS. Most indications
are that this dryline bulge will focus into the local forecast area,
probably over the Flint Hills region just west of Emporia and south
of Manhattan. An area of surface low pressure is also expected to
develop into this area. So, as the afternoon progresses, expect
effective heating to lead to a rather unstable airmass across the
forecast area. This instability is likely to be capped for much of
the day though as those veered winds aloft will bring a slightly
stronger EML into the local area.

What this all leads to is a conditional forecast for severe
thunderstorms. The main question will be if the cap can be broken
with only nebulous large scale lifting mechanisms (and even some
potential for weak subsidence aloft), and only modest convergence
along the dryline. IF thunderstorms are able to develop, it would be
in a very unstable environment with effective shear in the 35-40 kt
range which would be more than sufficient for supercells. It also
seems that if storms develop they would remain relatively discrete
owing to the convective inhibition, and would probably not develop
until peak heating. Thus, any storms that are able to develop can be
expected to become severe with very large hail and locally damaging
winds possible. Veered low level winds are not particularly
supportive of tornadoes, but the potential of a weak remnant outflow
boundary along with localized backing depending on the strength of
the surface meso-low in central KS means there is at least some
tornado potential with any long-lived supercell structures. The best
chance for initiation would be along the nose of that dryline bulge
with storm motion being almost due east.

Later tonight, convective coverage is in question, and it may focus
an area of development over far northeast KS where the LLJ
convergence maximizes in an unstable airmass. If this occurs, could
see areas of heavy rain as well as a continued severe weather threat
through the overnight hours.

.LONG TERM...(Thursday through Tuesday)
Issued at 415 AM CDT WED MAY 25 2016

Main focus for the period in terms of severe weather chances reside
on Thursday afternoon and then on Friday afternoon as the open
trough axis lifts through the central plains.  Exact details on
location and timing of convection is still uncertain and dependent
on Wednesday night convection and how quickly it clears which
currently appears during the morning hours. With the system becoming
more negatively tilted during the afternoon on Thursday, winds aloft
are expected to increase while sfc winds back towards the south and
southeast as the sfc low stretches across central KS. The dryline is
the likely trigger for convection to fire in
central KS by late afternoon. These storms are expected to track
eastward towards north central KS during the evening. Second area
for possible convection is along the expected outflow boundary
draped over the area from previous convection. With ample moisture
and available CAPE in excess of 4000 J/KG, it will not take much
forcing to initiate development. By the evening, LLJ increases with
a cluster of storms to center around the warm front near the KS and
NE border. These storms are likely to impact much of the area as the
low level jet veers overnight. Main threats are large hail and
damaging winds. Tornadoes are possible as well,
especially with any discrete cells or in vicinity to a boundary
through early evening. Localized flash flooding is likely given
the excessive rainfall these past few days.

By Friday, upper level dynamics increases as the trough lifts over
central KS, becoming more stacked with the sfc low and attendant
dryline. The dryline is expected to shift east into the CWA,
creating another a decent chance for thunderstorms to develop in the
late afternoon and evening. Shear profiles are sufficient to once
again see all modes of severe weather with decent low level shear
profiles in the early evening near the sfc low over north central
KS.

Highlights for the weekend into mid next week do not change much
from previous forecasts. As upper trough exits northeast Saturday
afternoon, could see additional storms in afternoon. Severe weather
is unlikely as effective shear is pretty weak, less than 20 kts.
Similar scenario is likely from Sunday onward as broad
southwest troughing continues to bring disturbances into the area.
Flash Flooding and River Flooding threats are very high through the
weekend. Rainfall totals through the weekend range from 1-4 inches
or more through Sunday. With little change in airmass, scattered
thunderstorms are possible for each period until perhaps Wednesday
when a cool front may finally bring a relief from the rainfall.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 1257 PM CDT WED MAY 25 2016

Outflow boundary from earlier thunderstorms along the Kansas river
at noon time, very near TAF sites. Ceilings should rise to VFR
shortly, while winds could be variable for the next 2 or 3 hours,
particularly at TOP and FOE before the boundary moves back north.
Isolated thunderstorms developing over central KS late this
afternoon may move through or near TAF sites by early evening so
have VCTS for a few hours during that time. Later tonight, moist
airmass could allow fog to form.

&&

.TOP Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Barjenbruch
LONG TERM...Prieto
AVIATION...GDP





000
FXUS63 KTOP 250548
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1248 AM CDT WED MAY 25 2016

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Wednesday)
Issued at 324 PM CDT TUE MAY 24 2016

A familiar synoptic pattern is seen in the 19Z water vapor imagery.
With a mean trough still over the west and northern Rockies,
southwesterly flow aloft remains over the central plains. A surface
low was again analyzed over the OK panhandle with a dryline
extending south through west TX. Outflow from morning storms has
muddled up the surface pattern over northeast KS and the better
moisture convergence is appears to be over southwest KS between the
surface low and the outflow boundary over southern KS.

A lot of this forecast is based on expected persistence of the
pattern and previous nights. Think that storms will once again
develop over southwestern KS and congeal into an MCS moving across
eastern KS tonight. The HRRR/ARW/NMM show a bowing MCS developing
this evening and move it across the forecast area by the late
evening. 0-6KM shear remains rather marginal around 30KT so the main
concerns with the storms will be damaging winds, hail and localized
flash flooding. Have likely POPs going tonight, but confidence is
only medium as some of the models still show various tracks to the
MCS. POPs taper down during the morning Wednesday as models move the
storms through earlier in the night. Although if an MCV is slow to
move east, there could be some lingering precip late in the morning.

Lows tonight should be in the lower to mid 60s with rain cooled air
helping to cool temps more so than they would be without precip.
Highs Wednesday are forecast to be in the lower and mid 80s as
models advect warmer air into eastern KS with 850MB temps warming to
around 22C and 700MB temps between 8 and 10C. Because of this,
forecast soundings show an elevated mixed layer capping the boundary
layer through much of the afternoon. So the question becomes whether
there is enough convergence along the dryline to force storms
because large scale forcing again appears to be weak at best. Most
guidance seems to keep the boundary layer capped as they do not
generate much QPF in the afternoon, so have kept some small POPs in
the forecast for Wednesday afternoon on the small chance a storm
develops.

.LONG TERM...(Wednesday Night through Tuesday)
Issued at 324 PM CDT TUE MAY 24 2016

Wednesday Night Friday...

Convective chances by early evening will be dependent on what
mesoscale boundaries will be present from any convection earlier in
the day. Otherwise the dryline and front will be located west of the
forecast area. There is not much in the way of upper support,
however the models suggest that there may be a weak wave moving out
of western Kansas into Nebraska Wednesday night. Instability,
moisture and shear will be sufficient for a few severe storms with
hail and wind the main hazards and a low probability for tornadoes.
Thursday may start out dry as models move off an MCS well east by
12Z Thursday. The models have slowed the ejection of the main energy
ejecting out of the western trough, but do eject a lead shortwave
out into the Plains Thursday afternoon and evening. Forecast
soundings show Steepening lapse rates and increasing shear around 30
to 35 kts toward 00Z Friday along with mlcape around 2500 J/kg.
Expect thunderstorms to develop along the front and dryline then
move northeast and east across the CWA during the evening and
overnight hours. Have maintained higher precipitation chances for
Thursday night and Friday as the upper level trough advances out
into the Plains. Forcing will also be aided by left exit region of
the upper jet across central and north central Kansas on Friday. Any
ongoing precipitation will likely leave mesoscale boundaries across
parts of the area by Friday afternoon.

Friday Night through Tuesday...

The active spring pattern will continue through the extended period.
Friday night an upper level trough across the four-corners region
will eject northeastward into the central plains. A strong vort-max
will will eject across the forecast area Friday evening into
Saturday morning, bringing likely chances for thunderstorms across
the entire area. Strong to severe thunderstorms will also be
possible as sufficient CAPE and shear will be in place. The
remainder of the period will consist of southwest flow aloft and
embedded weak upper-level waves. With the plentiful boundary layer
moisture that will be in place, have at least slight chance PoPs
through the remainder of the period.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 1247 AM CDT WED MAY 25 2016

Weakening TSRA complex moving through the terminals. Winds will be
a challenge over the next few hours but should become south to
southeast by 10Z. There continue to be signals of MVFR stratus
into the 18z period and will go along at this point. Too much
uncertainty for any late period TSRA at this point.

&&

.TOP Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Wolters
LONG TERM...Baerg/53
AVIATION...65





000
FXUS63 KTOP 240511
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1211 AM CDT TUE MAY 24 2016

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Tuesday)
Issued at 315 PM CDT MON MAY 23 2016

20Z water vapor imagery continues to show a mean trough over the
western U.S. with southwest flow persisting over the central plains.
A MCV is seen in the water vapor and profiler data near the KS/MO
state line and continues to slowly drift east. At the surface, an
area of low pressure was analyzed over the OK panhandle with an
inverted trough of low pressure extending through eastern NEB. Low
level trajectories remain favorable for low level moisture advection
north.

For tonight, the main question is where will the next round of
convection develop and where will the resulting MCS and/or MCV
track. High resolution models vary from storms over central NEB to
southwest KS. Overall, think convergence along the inverted trough
axis to the northwest of the forecast area should be the main focus
for redevelopment as low level moisture continues to advect north.
However given the uncertainty of where storms may track overnight,
the forecast only has POPs at 50 percent for the overnight hours and
into Tuesday morning. I think it may play out similar to today where
storms to the west generate an MCV and that causes showers and
storms to fester over the area for a good portion of the day.
Although there is low confidence in the location of the showers and
storms. Deep layer shear is progged to be somewhat better tonight
and Tuesday. So there should be a little better potential for severe
storms. If the MCS is able to form a good cold pool, There could be
strong winds and hail with the storms overnight. Lows tonight should
again be in the lower to mid 60s due to cloud cover and the moist
airmass remaining over the region. Highs Tuesday of around 80
degrees are based on mixing the boundary layer to around 875MB with
some insolation. This may be overdone though if an area of clouds and
precip linger for a long time over any location.

.LONG TERM...(Tuesday Night through Monday)
Issued at 315 PM CDT MON MAY 23 2016

Thunderstorm chances will continue to be the main concern through
the extended forecast. Initial concern will be convective chances
Tuesday evening and Tuesday night. Depending on the duration of any
thunderstorms during the day Tuesday and any mesoscale boundary
could focus convection in the evening if convergence is strong
enough. Otherwise convection firing off of the dryline in western
Kansas may move into parts of north central Kansas overnight into
early Wednesday morning as the low level jet veers across northeast
Kansas. Models show capping inversion across the area through the
day on Wednesday and most of the day may remain dry after initial
morning convection ends. Dryline is forecast to remain to the west
of the forecast area in the afternoon. The models hint at a weak
wave moving northeast out of Colorado in the late afternoon and may
help initiate storms in northwest and parts of north central Kansas.
Shear is favorable across north central Kansas for supercells where
0-6km shear of 45 to 50 kts is forecast along with an unstable
airmass. Additional energy may move out across western and central
Kansas Wednesday night, this along with convergence across southern
Nebraska and northern Kansas around 850 mb may also cause showers
and thunderstorms to train along the border overnight Wednesday into
early Thursday morning. On Thursday and Thursday night a more potent
upper level trough will move northeast across western and central
Kansas and should fire storms along the dryline that is forecast to
be just west of our CWA. Again shear and instability coupled along
with good forcing for ascent will likely lead to severe storms
across parts of north central and northeast Kansas. The dryline and
frontal boundary looks to remain just to the west of the forecast
area through Saturday before retreating westward on Sunday. This
will act as a focus each day for storms as weaker waves move out of
the western trough and out into the Plains. Shear is weaker over the
weekend and into next Monday across central and eastern Kansas and
there may be a few stronger storms across the area. Temperatures
through the period will remain in the upper 70s to mid 80s with lows
mainly in the 60s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday Night)
Issued at 1211 AM CDT TUE MAY 24 2016

MVFR cloud on the increase from the south and will be impacting
the terminals in the next few hours. Will be monitoring convective
trends but still appears a window around 11-14Z will be the main
window of potential.

&&

.TOP Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Wolters
LONG TERM...53
AVIATION...65





000
FXUS63 KTOP 232346
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
646 PM CDT MON MAY 23 2016

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Tuesday)
Issued at 315 PM CDT MON MAY 23 2016

20Z water vapor imagery continues to show a mean trough over the
western U.S. with southwest flow persisting over the central plains.
A MCV is seen in the water vapor and profiler data near the KS/MO
state line and continues to slowly drift east. At the surface, an
area of low pressure was analyzed over the OK panhandle with an
inverted trough of low pressure extending through eastern NEB. Low
level trajectories remain favorable for low level moisture advection
north.

For tonight, the main question is where will the next round of
convection develop and where will the resulting MCS and/or MCV
track. High resolution models vary from storms over central NEB to
southwest KS. Overall, think convergence along the inverted trough
axis to the northwest of the forecast area should be the main focus
for redevelopment as low level moisture continues to advect north.
However given the uncertainty of where storms may track overnight,
the forecast only has POPs at 50 percent for the overnight hours and
into Tuesday morning. I think it may play out similar to today where
storms to the west generate an MCV and that causes showers and
storms to fester over the area for a good portion of the day.
Although there is low confidence in the location of the showers and
storms. Deep layer shear is progged to be somewhat better tonight
and Tuesday. So there should be a little better potential for severe
storms. If the MCS is able to form a good cold pool, There could be
strong winds and hail with the storms overnight. Lows tonight should
again be in the lower to mid 60s due to cloud cover and the moist
airmass remaining over the region. Highs Tuesday of around 80
degrees are based on mixing the boundary layer to around 875MB with
some insolation. This may be overdone though if an area of clouds and
precip linger for a long time over any location.

.LONG TERM...(Tuesday Night through Monday)
Issued at 315 PM CDT MON MAY 23 2016

Thunderstorm chances will continue to be the main concern through
the extended forecast. Initial concern will be convective chances
Tuesday evening and Tuesday night. Depending on the duration of any
thunderstorms during the day Tuesday and any mesoscale boundary
could focus convection in the evening if convergence is strong
enough. Otherwise convection firing off of the dryline in western
Kansas may move into parts of north central Kansas overnight into
early Wednesday morning as the low level jet veers across northeast
Kansas. Models show capping inversion across the area through the
day on Wednesday and most of the day may remain dry after initial
morning convection ends. Dryline is forecast to remain to the west
of the forecast area in the afternoon. The models hint at a weak
wave moving northeast out of Colorado in the late afternoon and may
help initiate storms in northwest and parts of north central Kansas.
Shear is favorable across north central Kansas for supercells where
0-6km shear of 45 to 50 kts is forecast along with an unstable
airmass. Additional energy may move out across western and central
Kansas Wednesday night, this along with convergence across southern
Nebraska and northern Kansas around 850 mb may also cause showers
and thunderstorms to train along the border overnight Wednesday into
early Thursday morning. On Thursday and Thursday night a more potent
upper level trough will move northeast across western and central
Kansas and should fire storms along the dryline that is forecast to
be just west of our CWA. Again shear and instability coupled along
with good forcing for ascent will likely lead to severe storms
across parts of north central and northeast Kansas. The dryline and
frontal boundary looks to remain just to the west of the forecast
area through Saturday before retreating westward on Sunday. This
will act as a focus each day for storms as weaker waves move out of
the western trough and out into the Plains. Shear is weaker over the
weekend and into next Monday across central and eastern Kansas and
there may be a few stronger storms across the area. Temperatures
through the period will remain in the upper 70s to mid 80s with lows
mainly in the 60s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 646 PM CDT MON MAY 23 2016

VFR conditions should persist for the next several hours but
chances for limitations in clouds and/or precip seem to be
increasing for the 06Z-18Z window. Models showing some
consistency in cumulus field in west central Kansas developing
into convective cluster that moves east with time, aided by a
possible weak wave moving out of Colorado. Have gone ahead with
prevailing SHRA in most likely time of passage of this MCS.
Forecast soundings are also similar in rather moist lower levels
during this period bringing some potential for MVFR cigs in a
similar window.

&&

.TOP Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Wolters
LONG TERM...53
AVIATION...65





000
FXUS63 KTOP 231725
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1225 PM CDT MON MAY 23 2016

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 355 AM CDT MON MAY 23 2016

At 3 AM on Monday, a complex of thunderstorms was pushing east
across Nebraska with the southern flank and associated outflow
boundary extending into northern KS. This outflow seems to be pretty
shallow on the southern flank but is intersecting the low level jet
to create rather strong low level convergence. North central KS has
around 1000 J/kg of MUCAPE according to SPC mesoanalysis but RAP
forecast soundings indicate that those MU parcels rooted near or
just above the surface are being suppressed at the moment by a
capping inversion around 6000 feet. However, over the next few
hours, a weak short wave and associated upper cooling/height falls
will influence the region and all expectations are for this cap to
erode with a focus for thunderstorm development in north central KS
between 10Z and 12Z...and gradually shifting east into less unstable
air over eastern KS through the day. Effective shear is quite weak
this morning, and while a few severe storms are not out of the
question this AM, they would probably be limited to areas west of
HWY 77 in the first 1-3 hours of convective development...and see a
better chance for this activity to remain sub-severe with a further
weakening trend with eastward progression.

The morning/early afternoon convective overturning should do a
pretty good job of keeping much of the area stable through the day
and into the afternoon. However, expect at least some recharge into
north central KS by late afternoon where most guidance suggests a
band of 1000-2000 J/kg of MLCAPE to develop with limited inhibition
by late afternoon. Deep layer shear will also improve slightly in
this area with 30-40 kts of 0-6 shear. Do expect thunderstorm
development in this region between 4-7 PM, but unsure at this time
how far east the development will occur and it will depend on the
evolution of early day convection. For now, see at least some
conditional severe potential, again mainly focused west of an
Abilene to Manhattan to Marysville line.

Any diurnally driven afternoon storms will weaken by mid evening,
but see potential for another round of overnight storms probably
after 2 AM as the LLJ intensifies and focuses convergence into
central and northern KS. Unsure just how this will evolve, but given
very steep lapse rates and instability rooted just off the surface,
see a situation for which a forward propagating MCS could develop
with some associated wind and hail potential during the early
morning hours.  Obviously there is plenty of uncertainty throughout
this forecast, with each round of storms and its outflow having an
effect on subsequent storms.

.LONG TERM...(Tuesday through Sunday)
Issued at 355 AM CDT MON MAY 23 2016

The region looks to remain under an active weather pattern this week
and even through next weekend, with chances for showers and
thunderstorms essentially every day.  Models continue to show the
surface and mid-level features remaining fairly persistent through
the entire extended forecast period, noted by steady southwest flow
aloft and southerly surface flow that will contribute to ongoing
warm-air advection and moisture advection into the region. These
advection features will help to support sufficient instability
essentially every day this week.  While model soundings show a cap
developing almost daily, these caps appear to be weak enough to be
easily broken most days, thus supporting the development of surface-
based storms.

On Tuesday, an early morning MCS may be progressing eastward across
the CWA through the morning and cannot rule out a few isolated
strong storms embedded within this morning activity.  Precipitation
may clear out during the afternoon with several models suggesting
the development of additional storms late afternoon/early evening
across north central Kansas in the vicinity of the stationary
boundary. This additional thunderstorm development may also be
enhanced by an embedded mid-level shortwave near this boundary. If
storms are able to develop, they would likely advance into north
central Kansas during the evening hours and continue to spread
eastward overnight.  These storms should be moving out of eastern
Kansas Wednesday morning. Some model soundings suggest that a
slightly stronger cap may build in on Wednesday, however some models
have also been consistently showing a bulge in the dewpoints
possibly extending into central Kansas, which would likely be enough
to help break the cap and thus support strong to severe
thunderstorms once again late Wednesday afternoon and evening.

Thursday is increasingly looking like the best day for potential
severe thunderstorm development across the CWA.  There may not be
much in the way of morning convection, with model soundings showing
the cap quickly weakening through the afternoon hours as the dryline
advances into central Kansas.  Models are in good agreement with the
stationary boundary becoming more southwest-to-northeast oriented,
extending into north central and possibly even northeast Kansas
during the day. Models continue to show sufficient instability in
place, and it`s worth noting that the 0-6km bulk shear values have
increased in the 00z model runs to upwards of 40-50+kts by late
Thursday afternoon/early evening, especially across north central
and far northern Kansas.  With these conditions in place, there is
increasing concern for severe thunderstorms Thursday afternoon and
evening.  The stationary boundary will likely continue to linger
across north central Kansas Friday through the weekend, which will
help to support ongoing thunderstorm chances across the outlook
area.  While some strong to severe thunderstorms may be possible,
shear values look to diminish some into the weekend.

Here`s the bottom line: some strong to severe thunderstorms will be
possible across the outlook area every day this week, with all
severe threats possible: large hail, damaging winds, and possibly a
few tornadoes. Additionally, since several rounds of storms are
possible, there will be an increasing concern for flooding through
the week, especially if storms end up tracking over a particular
location from day to day.  There are still plenty of uncertainties
in the exact details of thunderstorm potential each day due to small
scale features such as potential lingering outflow boundaries.

As for temperatures, conditions will remain fairly steady through
the week and into the weekend with highs ranging from the upper 70s
to upper 80s and low temperatures staying in the 60s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 1220 PM CDT MON MAY 23 2016

VFR conditions are expected to continue into the overnight hours.
Showers and thunderstorms will continue to push eastward out the
Topeka terminals near 20Z. The big question mark through the
period is the development of an MCS across the area. Currently
have VCTS and MVFR cigs mentioned at MHK beginning at 09Z and 10Z
at the Topeka terminals. Later outlooks will continue to refine
timing of possible thunderstorms overnight.

&&

.TOP Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Barjenbruch
LONG TERM...Hennecke
AVIATION...Baerg





000
FXUS63 KTOP 231127
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
627 AM CDT MON MAY 23 2016

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 355 AM CDT MON MAY 23 2016

At 3 AM on Monday, a complex of thunderstorms was pushing east
across Nebraska with the southern flank and associated outflow
boundary extending into northern KS. This outflow seems to be pretty
shallow on the southern flank but is intersecting the low level jet
to create rather strong low level convergence. North central KS has
around 1000 J/kg of MUCAPE according to SPC mesoanalysis but RAP
forecast soundings indicate that those MU parcels rooted near or
just above the surface are being suppressed at the moment by a
capping inversion around 6000 feet. However, over the next few
hours, a weak short wave and associated upper cooling/height falls
will influence the region and all expectations are for this cap to
erode with a focus for thunderstorm development in north central KS
between 10Z and 12Z...and gradually shifting east into less unstable
air over eastern KS through the day. Effective shear is quite weak
this morning, and while a few severe storms are not out of the
question this AM, they would probably be limited to areas west of
HWY 77 in the first 1-3 hours of convective development...and see a
better chance for this activity to remain sub-severe with a further
weakening trend with eastward progression.

The morning/early afternoon convective overturning should do a
pretty good job of keeping much of the area stable through the day
and into the afternoon. However, expect at least some recharge into
north central KS by late afternoon where most guidance suggests a
band of 1000-2000 J/kg of MLCAPE to develop with limited inhibition
by late afternoon. Deep layer shear will also improve slightly in
this area with 30-40 kts of 0-6 shear. Do expect thunderstorm
development in this region between 4-7 PM, but unsure at this time
how far east the development will occur and it will depend on the
evolution of early day convection. For now, see at least some
conditional severe potential, again mainly focused west of an
Abilene to Manhattan to Marysville line.

Any diurnally driven afternoon storms will weaken by mid evening,
but see potential for another round of overnight storms probably
after 2 AM as the LLJ intensifies and focuses convergence into
central and northern KS. Unsure just how this will evolve, but given
very steep lapse rates and instability rooted just off the surface,
see a situation for which a forward propagating MCS could develop
with some associated wind and hail potential during the early
morning hours.  Obviously there is plenty of uncertainty throughout
this forecast, with each round of storms and its outflow having an
effect on subsequent storms.

.LONG TERM...(Tuesday through Sunday)
Issued at 355 AM CDT MON MAY 23 2016

The region looks to remain under an active weather pattern this week
and even through next weekend, with chances for showers and
thunderstorms essentially every day.  Models continue to show the
surface and mid-level features remaining fairly persistent through
the entire extended forecast period, noted by steady southwest flow
aloft and southerly surface flow that will contribute to ongoing
warm-air advection and moisture advection into the region. These
advection features will help to support sufficient instability
essentially every day this week.  While model soundings show a cap
developing almost daily, these caps appear to be weak enough to be
easily broken most days, thus supporting the development of surface-
based storms.

On Tuesday, an early morning MCS may be progressing eastward across
the CWA through the morning and cannot rule out a few isolated
strong storms embedded within this morning activity.  Precipitation
may clear out during the afternoon with several models suggesting
the development of additional storms late afternoon/early evening
across north central Kansas in the vicinity of the stationary
boundary. This additional thunderstorm development may also be
enhanced by an embedded mid-level shortwave near this boundary. If
storms are able to develop, they would likely advance into north
central Kansas during the evening hours and continue to spread
eastward overnight.  These storms should be moving out of eastern
Kansas Wednesday morning. Some model soundings suggest that a
slightly stronger cap may build in on Wednesday, however some models
have also been consistently showing a bulge in the dewpoints
possibly extending into central Kansas, which would likely be enough
to help break the cap and thus support strong to severe
thunderstorms once again late Wednesday afternoon and evening.

Thursday is increasingly looking like the best day for potential
severe thunderstorm development across the CWA.  There may not be
much in the way of morning convection, with model soundings showing
the cap quickly weakening through the afternoon hours as the dryline
advances into central Kansas.  Models are in good agreement with the
stationary boundary becoming more southwest-to-northeast oriented,
extending into north central and possibly even northeast Kansas
during the day. Models continue to show sufficient instability in
place, and it`s worth noting that the 0-6km bulk shear values have
increased in the 00z model runs to upwards of 40-50+kts by late
Thursday afternoon/early evening, especially across north central
and far northern Kansas.  With these conditions in place, there is
increasing concern for severe thunderstorms Thursday afternoon and
evening.  The stationary boundary will likely continue to linger
across north central Kansas Friday through the weekend, which will
help to support ongoing thunderstorm chances across the outlook
area.  While some strong to severe thunderstorms may be possible,
shear values look to diminish some into the weekend.

Here`s the bottom line: some strong to severe thunderstorms will be
possible across the outlook area every day this week, with all
severe threats possible: large hail, damaging winds, and possibly a
few tornadoes. Additionally, since several rounds of storms are
possible, there will be an increasing concern for flooding through
the week, especially if storms end up tracking over a particular
location from day to day.  There are still plenty of uncertainties
in the exact details of thunderstorm potential each day due to small
scale features such as potential lingering outflow boundaries.

As for temperatures, conditions will remain fairly steady through
the week and into the weekend with highs ranging from the upper 70s
to upper 80s and low temperatures staying in the 60s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
Issued at 621 AM CDT MON MAY 23 2016

Difficult and relatively low confidence TAF through the day today.
Many models are suggesting that MVFR cigs will build into TAF
sites for a prolonged period, but see the best chance for MVFR
cigs to be later this morning into early afternoon as an upper
storm system brings rain and storms across TAF sites. Expect some
mixing as rain ends with cigs likely scattering and lifting a
bit. Another round of storms possible after 06Z but exact timing
remains in question.

&&

.TOP Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Barjenbruch
LONG TERM...Hennecke
AVIATION...Barjenbruch





000
FXUS63 KTOP 230453
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1153 PM CDT SUN MAY 22 2016

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Monday)
Issued at 334 PM CDT SUN MAY 22 2016

20Z water vapor imagery shows a shortwave ridge from the Red River
valley into MN and WI with the upper trough over the western states.
A closed low was noted north of MT and another shortwave seen moving
across northern UT into WY. At the surface, a trough of low pressure
along the lee of the Rockies and ridging over the central MS river
valley have combined to funnel low level moisture north with mid 60s
dewpoints now in central KS.

Objective analysis suggests there remains some weak convective
inhibition across north central KS while the best low level
convergence remains over the TX panhandle and western KS. Since
there isn`t much indication of a shortwave or other forcing imminent
across central KS, think the afternoon and evening hours are likely
to remain dry. And really the biggest unknown is what will actually
force convection late tonight and Monday as there remains no real
obvious synoptic scale forcing from the models. At best there may
be inferred a subtle wave in the 500MB pattern by Monday morning, but
this is far from a clear forcing mechanism. Nevertheless most if not
all guidance is showing convection developing through the pre dawn
hours and continuing through the morning. Think that it should not
take much forcing for storm development given the potential
instability and the models lake of inhibition to convection. Maybe
all it will take is a weak MCV from the convection out west. Have
trended POPs down slightly given the lack of an obvious forcing
mechanism and to better collaborate with neighboring offices, but do
not feel comfortable lowering POPs much more since models have shown
a consistent signal for precip Through the day Monday.

Regarding severe potential, 0-6KM shear is progged to improve to
between 30 and 40 KT by Monday afternoon and a weak surface trough
is expected to set up just to the west of the forecast area. So
given the moist airmass and improving shear profile, there remains
the potential for severe storms. Thinking is that there may be
elevated storms through the morning and then the better chances for
severe storms could be late in the afternoon with potential
development along the surface trough axis if the airmass is able to
recover. Low level veering of winds with height favor a reasonable
curved hodograph with low LCL heights so there is some potential for
a tornado if storms redevelop. Large hail will likely be the most
likely hazard with any storms.

Given the uncertainty in how convection evolves over the next 24
hours, think that there could be some reasonable insolation
tomorrow. Because of this have adjusted highs up into the upper 70s
and around 80. Lows tonight should be mild due to continued
southerly flow and moisture advection. The forecast has lows in the
lower and middle 60s.

.LONG TERM...(Monday Night through Sunday)
Issued at 334 PM CDT SUN MAY 22 2016

Thunderstorm potential remains the main challenge through the
extended periods. Southwest flow aloft with southerly low level flow
continues to dominate much of these periods. There is also little if
any suggestion of strong capping building over the warm and moist
low levels, keeping unstable conditions intact. Forcing for
convection is the primary issue, and there are not many obvious
features for when chances will considerable greater or lesser. Weak
front should be laying up to the northwest of the area Monday night
into Tuesday, though precip could be ongoing Monday evening with
some moisture convergence allowing for continuation into these
periods. Models vary with push of dryline east across Kansas Tuesday
but tend to keep it well west. The 850-925mb layer also stays rather
moist all day and may keep destabilization in check. There is a
fairly consistent suggestion of a weak mid-level wave passing
through Tuesday night for somewhat greater storm potential. Drier
air moves in aloft behind this wave Wednesday with dryline possibly
having more luck moving this way, but capping potential with the
drier air loft does keep precip chances/coverage somewhat more
limited Wednesday and Wednesday night. The main upper trough finally
rotates into the area Thursday into Friday night, with timing
differences and the potential for multiple larger-scale waves in
this trough bringing questions on when the best storm potential will
be. Precip chances still look to linger into the weekend with
instability remaining and southwest flow/moisture returning.

Severe weather potential for much of these periods remains, largely
based on moderate to high instability as shear parameters are not
very impressive. Winds do look to increase aloft with the main trof
in the late week and could present the strongest overall potential
depending on timing of the waves. Heavy rainfall and flooding
chances continue with some chance of multiple rounds of convection,
though exactly where and when remains well uncertain.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1152 PM CDT SUN MAY 22 2016

Challenging forecast with timing of ceilings and convection this
period.  With the low level jet moving east over the area tonight,
model soundings have been hinting at LLWS at all terminals. Believe
this may be more on the marginal side, but have kept persistence
with previous forecasts to leave in this potential.  Overnight,
storms are expected to move in from the west impacting terminals
between 13-14Z.  Along with storms, ceilings will also deteriorate
to MVFR at the same time.  From here, lingering storms could be seen
through early afternoon before a brief break is seen in
precipitation.  Exact timing is still being worked out, but a
clearing from roughly 22-23Z to 01-02Z is possible before storms
move through again tomorrow night.

&&

.TOP Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Wolters
LONG TERM...65
AVIATION...Heller





000
FXUS63 KTOP 222336
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
636 PM CDT SUN MAY 22 2016

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Monday)
Issued at 334 PM CDT SUN MAY 22 2016

20Z water vapor imagery shows a shortwave ridge from the Red River
valley into MN and WI with the upper trough over the western states.
A closed low was noted north of MT and another shortwave seen moving
across northern UT into WY. At the surface, a trough of low pressure
along the lee of the Rockies and ridging over the central MS river
valley have combined to funnel low level moisture north with mid 60s
dewpoints now in central KS.

Objective analysis suggests there remains some weak convective
inhibition across north central KS while the best low level
convergence remains over the TX panhandle and western KS. Since
there isn`t much indication of a shortwave or other forcing imminent
across central KS, think the afternoon and evening hours are likely
to remain dry. And really the biggest unknown is what will actually
force convection late tonight and Monday as there remains no real
obvious synoptic scale forcing from the models. At best there may
be inferred a subtle wave in the 500MB pattern by Monday morning, but
this is far from a clear forcing mechanism. Nevertheless most if not
all guidance is showing convection developing through the pre dawn
hours and continuing through the morning. Think that it should not
take much forcing for storm development given the potential
instability and the models lake of inhibition to convection. Maybe
all it will take is a weak MCV from the convection out west. Have
trended POPs down slightly given the lack of an obvious forcing
mechanism and to better collaborate with neighboring offices, but do
not feel comfortable lowering POPs much more since models have shown
a consistent signal for precip Through the day Monday.

Regarding severe potential, 0-6KM shear is progged to improve to
between 30 and 40 KT by Monday afternoon and a weak surface trough
is expected to set up just to the west of the forecast area. So
given the moist airmass and improving shear profile, there remains
the potential for severe storms. Thinking is that there may be
elevated storms through the morning and then the better chances for
severe storms could be late in the afternoon with potential
development along the surface trough axis if the airmass is able to
recover. Low level veering of winds with height favor a reasonable
curved hodograph with low LCL heights so there is some potential for
a tornado if storms redevelop. Large hail will likely be the most
likely hazard with any storms.

Given the uncertainty in how convection evolves over the next 24
hours, think that there could be some reasonable insolation
tomorrow. Because of this have adjusted highs up into the upper 70s
and around 80. Lows tonight should be mild due to continued
southerly flow and moisture advection. The forecast has lows in the
lower and middle 60s.

.LONG TERM...(Monday Night through Sunday)
Issued at 334 PM CDT SUN MAY 22 2016

Thunderstorm potential remains the main challenge through the
extended periods. Southwest flow aloft with southerly low level flow
continues to dominate much of these periods. There is also little if
any suggestion of strong capping building over the warm and moist
low levels, keeping unstable conditions intact. Forcing for
convection is the primary issue, and there are not many obvious
features for when chances will considerable greater or lesser. Weak
front should be laying up to the northwest of the area Monday night
into Tuesday, though precip could be ongoing Monday evening with
some moisture convergence allowing for continuation into these
periods. Models vary with push of dryline east across Kansas Tuesday
but tend to keep it well west. The 850-925mb layer also stays rather
moist all day and may keep destabilization in check. There is a
fairly consistent suggestion of a weak mid-level wave passing
through Tuesday night for somewhat greater storm potential. Drier
air moves in aloft behind this wave Wednesday with dryline possibly
having more luck moving this way, but capping potential with the
drier air loft does keep precip chances/coverage somewhat more
limited Wednesday and Wednesday night. The main upper trough finally
rotates into the area Thursday into Friday night, with timing
differences and the potential for multiple larger-scale waves in
this trough bringing questions on when the best storm potential will
be. Precip chances still look to linger into the weekend with
instability remaining and southwest flow/moisture returning.

Severe weather potential for much of these periods remains, largely
based on moderate to high instability as shear parameters are not
very impressive. Winds do look to increase aloft with the main trof
in the late week and could present the strongest overall potential
depending on timing of the waves. Heavy rainfall and flooding
chances continue with some chance of multiple rounds of convection,
though exactly where and when remains well uncertain.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 636 PM CDT SUN MAY 22 2016

Main forecast concerns of the period will be LLWS, timing for
convection, and when low ceilings move in tomorrow.  Have kept
previous forecast for LLWS tonight through early morning due to
model soundings indicating this potential.  Hires models are still
showing signals for storms to move through between 11-14Z for all
terminals and have included VCTS from this time through the end of
the period as storms may redevelop in the afternoon.  With abundant
low level moisture, MVFR cigs are expected to move in tomorrow from
west to east.  IFR ceilings are possible, but with uncertainties in
storm coverage and timing which play a role in this, have not
mentioned lower than MVFR ceilings in this TAF issuance.

&&

.TOP Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Wolters
LONG TERM...65
AVIATION...Heller





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