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Area forecast discussion...updated aviation 
National Weather Service Saint Louis MO
700 PM CDT Thursday Jul 28 2016

Short term... (through friday)
issued at 257 PM CDT Thu Jul 28 2016

(tonight)

Three items are the principle focusing mechanisms for convection
this afternoon. The first is the main cold front now located
southeast of stl Metro, draped from southern Illinois thru southeast MO.
The second is an upper level disturbance located over stl Metro.
The third is a weaker, secondary trough located from northwest Illinois
thru northeast MO. With a weakly sheared, moderately unstable
environment with little-no cinh, showers and storms are popping up
all over, but mainly in those three areas.

Convection is being greatly enhanced with diurnal influences and
should lessen with loss of heating early this evening and into the
overnight, with an overall trend towards areas south of I-70 as it
does so. Many areas should be dry overnight, with models now taking
a mesoscale convective system track well to the west.

Generally favored the higher min temps on the met MOS, yielding
upper 60s to around 70.

(Friday)

While mesoscale convective system should miss our area to the west, it appears the secondary
trough should be in the southern County Warning Area once diurnal influences kick into
gear again, and it is in this area where the highest pops will be,
beginning just before midday and continuing thru the afternoon
hours. Lesser chances for showers and storms will exist elsewhere.
Otherwise, look for Max temps to be a few degrees less than
persistence, thanks to cooler air filtering in behind that secondary
trough.

Tes

Long term... (friday night through next thursday)
issued at 257 PM CDT Thu Jul 28 2016

(this weekend)

NAM and GFS are still showing west northwesterly flow setting up
over the area this weekend with a series of weak vort maxes that
will move southeast through it. There will still be a wavy frontal
boundary beneath this upper flow that will continue to act as a
focus for scattered thunderstorm development, particularly during
the daytime when instability will be maximized and cinh will be the
lowest.

Temperatures over the weekend will stay in the 80s, with 850mb
temperatures in the 15-18c range.

(Monday through thursday)

Forecast for next week is not as clear as it was yesterday as global
models are not as in as good agreement. It still looks like the
upper trough will move east and off the East Coast by early-mid
week. This will keep a stalled front over the region into Tuesday
keeping showers and thunderstorms in the forecast. However, the GFS
and European model (ecmwf) now differ on how strong the upper high will build into
Midwest by the middle of next week. The GFS is more robust next week
in building the upper ridge over the area on Wednesday and Thursday.
Still expect temperatures will warm up quickly next week though once
the upper trough moves to the east of the area as 850mb temperatures
warm into the lower 20sc.

Britt
&&

Aviation... (for the 00z tafs through 00z Friday evening)
issued at 656 PM CDT Thu Jul 28 2016

Isolated storms continue to pop up as weak trof sinks south
through forecast area. For now just have vicinity thunderstorms
for KUIN and Metro area tafs through 01z Friday, as they should
diminish as sun sets. Otherwise, dry VFR conditions to persist
with northwest to north winds backing to the west by mid morning
on Friday.

Specifics for kstl:
isolated storms continue to pop up as weak trof sinks south
through forecast area. For now just have vicinity thunderstorms
for Metro area tafs through 01z Friday, as they should diminish
as sun sets. Otherwise, dry VFR conditions to persist with
northwest to north winds backing to the west by 15z Friday.

Byrd
&&

Lsx watches/warnings/advisories...
MO...none.
Illinois...none.
&&

$$
Weather forecast office lsx

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