Area forecast discussion
National Weather Service North Platte NE
235 PM CDT Sat may 18 2013
Mesoscale discussion...
issued at 235 PM CDT Sat may 18 2013
Severe thunderstorm potential still on track this afternoon and
evening. Latest surface analysis has a surface low pressure center located
in eastern Colorado...with a dry line extending south from the
low center through the Texas Panhandle and warm front east northeast
across northern Kansas. Surface low should continue to lift slowly
northward to near Goodland by late afternoon a warm front will
arc northeast into southwest Nebraska from the low center.
Thunderstorms should initiate around Imperial and Hayes Center
around 400 PM CDT on the nose of very steep low level lapse
rates/dry line which will be punching into far southwest Nebraska.
Storms likely to become supercells quickly as they move northeast
into a very to extremely unstable and favorable sheared
atmosphere. Backed surface winds to the southeast are expected across
most of southwest Nebraska...with speeds increasing just off the
surface early this evening. The time frame from 600 PM CDT to 900 PM
CDT looks to be the most favorable for tornado development across
southwest Nebraska. In addition to the tornado threat...very large
hail...possible baseball size or larger...is expected. Storms will
likely merge early this evening into a complex as they advance
northeast toward central and north central Nebraska. Large hail
and damaging winds will be the main threats from the complex.
&&
Synopsis...
issued at 235 PM CDT Sat may 18 2013
At 500 mb upper trough over The Rockies and ridging into Great Lakes.
At the surface surface low over northwest Kansas with inverted
trough into central South Dakota and dry line from eastern Colorado
through the Texas Panhandle.
&&
Short term...(this evening through sunday)
issued at 235 PM CDT Sat may 18 2013 thunderstorms expected through much of the
night across western and north central Nebraska. Initial round of
storms expected to develop/move northeast from southwest
Nebraska...through central and into north central Nebraska. Backed
surface winds to the southeast are expected across most of southwest
Nebraska...with speeds increasing just off the surface early this
evening. The time frame from 600 PM CDT to 900 PM CDT looks to be
the most favorable for tornado development across southwest
Nebraska. In addition to the tornado threat...very large
hail...possible baseball size or larger...is expected. Storms will
likely merge early this evening into a complex as they advance
northeast toward central and north central Nebraska. Large hail
and damaging winds will be the main threats from the complex.
After this initial round...additional elevated thunderstorms are possible
just about anywhere across western and north central Nebraska. These
will be the result of a strengthening low level jet and continued
large scale ascent.
Models not in very good agreement Sunday...and this is not a
surprise due to the large amount of convection expected tonight.
Basically a large upper level low will slowly migrate east across
the Central Plains Sunday and beyond. Convection will likely dictate
the actual location of the feature. For now it appears it may be in
or very near the forecast area Sunday...so higher probability of precipitation will be
maintained. There could be some stronger storms along the cold front
that will be located in central Nebraska during the late
afternoon.
Long term...(sunday night through saturday)
issued at 235 PM CDT Sat may 18 2013
Models have some problems with handling of 500 mb low for the next
several days but still all in all with Suttle differences wide
spread precipitation expected for most of western and north
central Nebraska through Wednesday. This will bring concerns for
hydrology. Severe weather focus over north central Nebraska on
Sunday east of a line from Ainsworth to Broken Bow. NAM fastest
and driest model and outlier from ec and GFS. Have trended more
towards the ec and GFS slower solution. Models have warmed some in
the extended with +6c at 850mb by 12z Wednesday and then a
gradual increase through the end of the period. Next system moves
into western Nebraska Thursday into Saturday. Have retained slight
chances.
&&
Aviation...(for the 18z tafs through 18z Sunday afternoon)
issued at 235 PM CDT Sat may 18 2013
MVFR conditions will continue to be possible across portions of
western and north central Nebraska this afternoon in areas of
lower stratus clouds.
Thunderstorms...some severe...will develop across southwest Nebraska late this
afternoon...and spread northeast across the entire area through
the evening. Winds will be southeast...but variable and gusty near
any storm.
&&
Lbf watches/warnings/advisories...
none.
&&
$$
Mesoscale...Taylor
synopsis...power
short term...Taylor
long term...power
aviation...Taylor
