Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 220502
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1202 AM CDT FRI APR 22 2016
...Update to aviation forecast discussion...
.SHORT TERM...(This Evening through Friday)
Issued at 335 PM CDT THU APR 21 2016
Latest water vapor satellite loop shows the center of the upper
level low over south central Iowa at 19Z. Lobes of vorticity were
rotating around the upper low with one dropping south across eastern
Nebraska. Isolated showers continue to pop up across northeast
Kansas and short term models, while overdone, show isolated showers
continuing through 00Z across northeast Kansas. The upper low will
gradually move eastward and widespread cumulus clouds should
dissipate with the loss of heating this evening allowing skies to
clear. Northwest winds will decrease tonight as high pressure builds
into the area overnight. Enough mixing in the low levels is expected
to keep any fog development to sheltered areas. Lows tonight will
cool into the lower to upper 40s.
Highs pressure will reside over eastern Kansas on Friday with light
winds expected for much of the day. With plenty of sunshine
temperatures will warm to the upper 60s to mid 70s with the warmer
temperatures near central Kansas where southerly return flow starts
up in the afternoon.
.LONG TERM...(Friday Night through Thursday)
Issued at 335 PM CDT THU APR 21 2016
Saturday and Saturday night, an upper level trough will dig east-
southeast across NV and UT, then east across CO and northern NM by
12Z SUN. A lee surface trough will deepen across the high plains of
eastern CO and eastern NM. Deeper gulf moisture will begin to be
transported north and northeast across central KS Saturday night.
There may be enough lift as the LLJ increased to 40 to 50 KTS for a
few elevated thunderstorms may develop in the early morning hours of
12Z Saturday, a downstream upper level ridge will amplify across the
southern and central plains and shift eastward into the mid and
lower MS river valley Saturday night. Saturday will be warmer as
southerly winds increase to 15 to 25 MPH with gusts to 35 MPH during
the afternoon hours. Highs will be in the upper 70s to lower 80s.
Sunday and Sunday night, The upper level trough across northern NM
and CO will lift northeast into western NE and western KS. A surface
dryline will push east into central KS during the afternoon hours.
Showers and thunderstorms will develop along and ahead of the
surface dryline from eastern NE, south-southwest across central KS.
The 850mb winds will veer a bit to the south-southwest through the
mid afternoon hours. There should be sufficient deep moisture return
across eastern KS with steep lapse rates from the surface to 800 mb
for about 1500-2200 J/KG of MLCAPE during the afternoon hours. 0-6KM
effective shear is forecasted to increase to 40 to 50 KTS during the
afternoon hours. Initially the 0-1KM SRH will be under a 100 j/kg but
may increase during the evening hours to near 200 j/kg as 850mb and
surface winds back a bit at or just after 00Z MON. The mode of
convection may start out as isolated to scattered supercells with
the primary hazard being damaging winds and large hail. Most models
show the scattered storm merging into a squall line. If a squall
line were to develop then the tornado threat would diminish even
though the low-level vertical windshear may increase towards 00Z MON.
If Isolated storms develop ahead of the squall line then there could
be an increased risk from tornadoes with any isolated supercells
late this afternoon. There may be a chance for mesovorticies within
a squall line if there is no isolated thunderstorms ahead of the
squall line. Highs Sunday afternoon should reach the mid to upper
70s with some breaks in the cloud cover during the early afternoon
hours. The line of storms should move east of the CWA during the mid
and late evening hours.
We may see a break in the active weather pattern Monday into Monday
night, as the surface cold front pushes south of the CWA. An intense
upper level trough will dig southeast into the southwestern US.
Tuesday, the intense upper level trough across southwestern US will
lift northeast as negative tilt trough into western KS during the
afternoon hours. The surface warm front across southern KS will lift
northward through the day. There will be strong vertical windshear
and and moderate instability as the 75-90 KT h5 jet lifting northeast
across eastern KS during the afternoon hours. The latest 12Z ECMWF
shows the warm front lifting to or just north of I-70. The dryline
will push northeast into east central KS by 00Z WED. Surface based
supercell will develop ahead of the dryline and move northeast. A
lot could change on the timing of the H5 trough lifting northeast
and the progression of the dryline and warm front. If the forecast
models continue to show this type of environment developing across
the eastern half the the CWA then there is a potential for a severe
weather outbreak Tuesday afternoon. The hazards from supercells on
Tuesday afternoon would include large hail, damaging winds and
possible tornadoes. The upper trough will lift northeast into the
upper midwest and the dryline and cold front will move east of the
area during the late evening hours of Tuesday.
Wednesday through Thursday, we will be between upper level troughs.
Expect dry conditions with a chance for showers and thunderstorms
late Thursday afternoon and Thursday night.
.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
Issued at 1201 AM CDT FRI APR 22 2016
Only issue at TOP/MHK will be potential for BR development,
although soundings indicate saturated layer is rather shallow and
wind speeds as high comes in still around 10kts near the NE
border. Will carry MVFR tempo visby at this time and monitor for