Area Forecast Discussion
Issued by NWS Springfield, MO
FXUS63 KSGF 300757
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
257 AM CDT Tue Jun 30 2015
.SHORT TERM...(Today and Tonight)
Issued at 257 AM CDT TUE JUN 30 2015
Northwest flow remains in place across the region this morning, with
a strong ridge centered over the Great Basin, and a large scale
trough over Hudson Bay into the Great Lakes. Numerous shortwaves
will continue to move across the Nation`s midsection through the
week, resulting in a rather unsettled forecast with low
confidence/predictability regarding exact details, especially PoPs
and temperatures for much of the week.
The daytime hours today look to be generally warm and dry, with
highs topping out in mid to upper 80s east and low 90s west.
Despite warm temperatures and ample low level moisture, mid level
dry air and rising heights aloft (along with a general lack of
forcing) should keep convection at bay through this afternoon. I
suppose a very isolated thunderstorm couldn`t be entirely ruled out
along some of the more complex terrain of southern Missouri, but
overall chances look to be less than 10 percent.
That will change going into tonight, however, as convection is
expected form along a frontal boundary over Nebraska/Iowa/northern
Missouri and move southeast as a convective complex. Initial
surface based convective initiation should be late afternoon or
early evening, with upscale growth then expected as the low level
jet strengthens through the late evening into the overnight. The
biggest forecast challenge at this juncture is 1.) where exactly
this complex will track and 2.) severe weather potential associated
with it. Concerning the track, assuming that convection develops
where expected, Corfidi vectors suggest a track more or less along
the Missouri River, with the potential for a turn a bit more to the
south over the eastern Ozarks, following the low level theta-e
gradient. This would suggest that areas along/east of a Warsaw to
Lebanon to West Plains line will have the highest potential of
seeing this complex, though much will depend on where exactly the
southward turn takes place. Additional elevated convection may
develop back to the west (toward the U.S. 65/ Hwy 13 corridors), as
the LLJ overrides any outflow.
The severe weather potential remains in question at this point.
Much will depend on the quality of the low level airmass along the
track of the MCS, especially the ability of any portion of the MCS
to be surface based during the late night hours. If portions of the
line can become/remain at least quasi-surface based, then some stronger
wind gusts will certainly be possible, if not likely. However,
assuming the system remains generally elevated, it`s questionable
just how much wind will be able to make it to the surface. Freezing
heights should generally be high enough to preclude any significant
hail. The severe weather potential will certainly be a short term
forecast focus through the day today, with the potential for
significant changes to expectations on short notice.
In addition to the severe weather threat, hydro/flooding will also
be a concern. Soils across the region are relatively saturated,
with six hour flash flood guidance at or below 3 inches in many
areas across central Missouri and the eastern Ozarks. Strongly
considered a Flash Flood Watch for portions of the area, but after
coordination with surrounding offices, will give the day shift a
chance to evaluate the latest forecast information later today and
hopefully fine tune the details a bit more. Given the chance for
fairly heavy rain not only tonight but over the next few nights, I
suspect a Watch will eventually be needed for central Missouri and
the eastern Ozarks.
.LONG TERM...(Wednesday through Monday)
Issued at 257 AM CDT TUE JUN 30 2015
Heading into the day Wednesday, convection will remain possible over
much of the area, as remnant outflow serves as a focus for
development. Right now the highest chances look to occur east of
U.S. 65, though much will depend on where outflow sets up. It`s not
entirely clear right now just how widespread convection will be
Wednesday, and this will have significant impacts on high
temperatures. Over southeastern Kansas, where PoPs are lowest,
temperatures will likely warm into the low 90s. Where convection is
most widespread over the eastern Ozarks, highs may have trouble
reaching 80. Certainly a high bust potential Wednesday.
More convection/another MCS then looks to develop Wednesday night,
possibly right over the forecast area, as the low level jet
interacts with the low level baroclinic zone. Right now this looks
most likely to be over the eastern Ozarks and south central
Missouri, though confidence is low in the exact areas. Wherever
this convection does develop, another round of heavy rain and
potential flooding will be possible, especially if it affects any
locations also affected by tonight`s MCS.
Model guidance is then in general agreement in pushing the low level
frontal zone a bit more south and west Thursday. Depending on how
far south and west the front makes it, this may give at least
central Missouri a little bit of a break from the "ring of fire".
For southern and western portions of the forecast area, the front
could remain close enough for result in decent rain chances.
That front will then remain in the general area through the weekend,
with numerous shortwaves embedded within northwest flow interacting
with it to produce scattered thunderstorms. It doesn`t appear that
the holiday weekend will necessarily be a washout, though it may be
necessary to dodge showers and storms at times. Temperatures will
be highly dependent on convective coverage, but overall look to be
at or just above normal.
.AVIATION...(For the 06Z TAFS through 06Z Tuesday Night)
Issued at 1203 AM CDT TUE JUN 30 2015
VFR conditions are expected over the next 24 hours. Light winds
are expected tonight and then again Tuesday evening. During the
day Tuesday expected westerly winds.