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Area forecast discussion 
National Weather Service Hastings NE
318 PM CDT Wednesday Jul 1 2015

Short term...(this evening through thursday)
issued at 318 PM CDT Wednesday Jul 1 2015

Map analysis indicates upper tropospheric ridging over the
western Continental U.S. And a trough over the east. An upper tropospheric
short wave is also noted over southern Alberta and southern
Saskatchewan. Enhanced upper tropospheric flow extends from
southwestern Canada...southeast into the northern and Central
Plains...and then into the Ohio River valley. Upper tropospheric
flow over our area maxes out at around 60kts near 40000ft above ground level per
12z sounding data from klbf and koax. At the surface...an area of
low barometric pressure is noted over eastern Kansas and as a
result...boundary- layer flow across the area remains from the
east/northeast.

Guidance suggests the upper tropospheric short wave...currently
over portions of southwestern Canada...will move southeast through
the next 24 hours...likely moving over the northern High Plains by
12z Thursday...and into portions of the Missouri River valley by
00z Friday. The area of low barometric pressure across eastern
Kansas is also expected to move southeast through the next 24
hours as weak surface ridging infiltrates the Central Plains. This
should promote a continued east/northeasterly boundary-layer wind
field across our area to start the forecast period...with this
wind expected to become light and variable tonight into the day
Friday.

Lingering cloud cover over our northeastern County Warning Area has kept
temperature readings down somewhat today...but early afternoon
satellite image indicates this cloud cover is diminishing somewhat
and if this trend continues...increased diabatic heating should
allow late afternoon / early evening temperature readings to climb
into the middle 80s across our northeast. Forecast proximity
soundings from across our northeast...per the NAM and operational
GFS...suggest isolated convection could result should sufficient
diabatic heating be realized. Although there has been plenty of
sunshine across our southwest today...warmer lower to middle
tropospheric temperature readings have provided a strong capping
inversion and as a result...the probability of convective
initiation across our southwest seems next to none. Given all
this...went ahead with 20% probability of precipitation...generally along and northeast of
a line from Ord to Geneva...during the 22-02z time frame. Although
this is a very low probability...if convection is realized across
our northeast late this afternoon into early this evening...then
potential energy of 1000-1500j/kg and deep-layer bulk shear values
of ~40kts could promote hail production. Given this...will go
ahead and mention a strong storm in the severe weather potential statement with nickel-size hail
and brief wind gusts to around 50 miles per hour.

Dry conditions are then expected across the entire County Warning Area once
diabatic heating is lost Post-sunset. But guidance suggests
chances for precipitation will increase across the region as the
aforementioned upper stratospheric short wave approaches from the
northwest. In fact...the NAM...operational GFS and ec all suggest
precipitation will be possible and as a result...went ahead with
40-60% probability of precipitation across the County Warning Area during the day Thursday. Increased
cloud cover should hinder diabatic heating across much of the County Warning Area
on Thursday and as a result...a strong capping inversion should
keep any convection elevated and sub-severe. In fact...at this
time it does not appear that potential energy values will exceed
1000j/kg at most locations and given this...will only mention a
few strong storms with nickel-size hail and wind gusts to around
50 miles per hour on Thursday.

Long term...(thursday night through wednesday)
issued at 318 PM CDT Wednesday Jul 1 2015

Precipitation chances remain in the forecast for the start of the
long term period Thursday night...as an upper level disturbances
continues shifting southeast out of plains and into the Midwest
region. At the surface...the accompanying frontal boundary which had
been sagging south starts to lose its push as the disturbance
moves further away...with models showing it stalling out and
becoming fairly diffuse in nature. Model quantitative precipitation forecast fields continue to
show some variation...but the better precipitation chances should be
drifting south with time...and look to be more scattered...so kept
probability of precipitation confined to the 20-30 percent range. Cant rule out additional
scattered thunderstorm chances as we get into the daytime hours on
Friday...with the potential for another weaker upper level
disturbance moving in...and some lift from the exit region of a
jet streak in the area. The surface pattern across the area on Friday
remains pretty weak...and light/variable winds are expected across
the County Warning Area. High temperatures are forecast to range from near 80 in
the east /which would have best chance of being affected by more
cloud cover/precip/ to the middle/upper 80s in the southwest. The
forecast for Friday night is currently dry.

Looking ahead to the upcoming July fourth Holiday...first thing
to state is that in regard to precipitation chances...confidence
in the models and thus the forecast is low and subject to change
in the coming days as models hopefully tune into a common theme.
Saturday morning...expecting to see a continuation of the upper
level northwesterly flow across the central Continental U.S.. models are in
decent agreement showing yet another upper level disturbance
making its way into the region...with the trough axis sitting
across portions of the County Warning Area during the daytime hours on Saturday.
Although forcing is on the weak side...as is the exit region of
the upper level jet in the area...it is there...and certainly cant
rule out at least a few showers/thunderstorms later in the
day...possibly lingering into the evening. Models also show late
day High Plains thunderstorm development...which could drift far
enough east overnight to affect the County Warning Area. Because overall
confidence in these chances is low...didnt go higher than 20
probability of precipitation...so odds are most will see dry conditions for the 4th...just
cant completely rule chances out at this point. High temperatures
are expected to be around average for this time of year...and are
forecast to range from the lower 80s east to near 90 in the SW.

As we get into Sunday...depending on how things pan out Saturday
night...could see some lingering activity across portions of the
County Warning Area...but better chances look to move in Sunday night and into the
first part of the work week. Models are in decent agreement
showing the upper level flow across the area transitioning to a
more zonal pattern...thanks to energy associated with an expansive
low pressure system over far north/central Canada. The initial piece
of energy looks to swing through Sunday night/Monday...with an
accompanying surface front pushing through much of/if not all of the
County Warning Area by Monday evening. Where this front ends up
settling/meandering getting into Tuesday will determine how much
of the County Warning Area is affected by precipitation chances as another disturbance
moves in. Following highs on Sunday in the middle 80s to lower
90s...this front is currently forecast to drop highs by Tuesday into
the middle/upper 70s.

&&

Aviation...(for the 18z kgri/kear tafs through 18z Thursday afternoon)
issued at 1249 PM CDT Wednesday Jul 1 2015

VFR conditions at kear until 09z...with MVFR 09z Onward. MVFR
conditions expected at kgri until 19z...followed by VFR until
09z...and then MVFR to finish the taf period.

A small area of stratus...with a ceiling generally in the
1000-1500ft above ground level range...persists over portions of eastern and
central Nebraska as of this writing. At this time...a resultant
MVFR ceiling is expected to persist at kgri until 19z...with VFR
conditions then expected this afternoon into tonight. There is a
chance MVFR conditions could persist for a time beyond 19z at
kgri...but this will be handled with amendments if necessary. Kear
is currently far enough west of the stratus...thus the VFR
condition which are forecast this afternoon into this evening.
Another period of MVFR conditions are then expected at both taf
sites starting 09z as a low ceiling and perhaps restricted
visibility infiltrates the area. Chances for the showers and
thunderstorms also exist in the forecast for both sites starting
early Thursday morning and given this...went ahead with thunderstorms in the vicinity 09z
Onward. The surface wind will start the taf period from the
east/northeast at around 08kts...but become light and variable
tonight into the day Thursday.



&&

Gid watches/warnings/advisories...
NE...none.
Kansas...none.
&&

$$

Short term...Bryant
long term...adp
aviation...Bryant/petr

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