Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
1044 PM EDT Sat may 23 2015
high pressure will extend over the region today. The center of
the high will move off the middle Atlantic coast by Sunday. Moist
return flow around the high will interact with embedded disturbances
aloft to bring the threat for showers and thunderstorms to the
region next week.
Near term /until 2 am Sunday morning/...
highly amplified middle/upper level flow with ridge axis over the MS
valley building east into the Ohio Valley Sunday. Sprawling surface high
pressure builds a little east becoming centered off the East Coast
by Sunday morning.
Dry airmass at place...with iln/S 00z sounding showing a mixing up
to about 775 mb. This allowed maximum temperatures to top out in upper
70s to lower 80s.
In warm air advection pattern expect high clouds to increase with an increase in
middle level clouds late tonight into Sunday morning. These middle level
clouds will pivot north and thin out during the morning.
With an increase in clouds in warm air advection pattern lows will be 5 to 10
degrees warmer Sunday morning. Expect lows from the lower 50s to
the upper 50s.
Short term /2 am Sunday morning through Monday night/...
Sunday looks to be the last dry day before rain chances return
across the area. An upper level low currently over The Rockies
will remain quasi- stationary Sunday allowing 500 heights to rise
from 576 dm to near 586 dm by Sunday. Going through the forecast
soundings for Sunday it appears that there will be just not enough
moisture for rain yet. Precipitable waters are forecasted to be around 1.05" but
on both the GFS and NAM there is a dry slot still around 850 to
700 mb. Temperatures Sunday will be a couple of degrees warmer
than today as 850 temperatures are forecasted to rise from 9
degrees c to near 13 degrees c. Models are showing more clouds for
tomorrow than today but given the warmer start for Sunday am
keeping forecast warmer Sunday than today by a couple of degrees.
On Monday an area of positive vorticity rounds the base of the low
over The Rockies and helps to push the ridge axis further east
opening the way for the chance rain to return. The 850/700 dry
air from Sunday erodes with precipitable waters rising to around 1.50" on both
the NAM and GFS forecast soundings. Models are also showing
multiple upper level disturbances moving overhead Monday that are
embedded in the flow. Both GFS and NAM soundings also support
thunder with parcels being able to make it up through the freezing
Rain chances will then continue even through the night as rain
can't be ruled out due to continuing upper level disturbances
moving over the region. Low temperatures Monday morning will also
be much warmer with lows in the middle 60s forecasted.
Long term /Tuesday through Saturday/...
a ridge axis will remain in place across the eastern Seaboard
through the middle part of the upcoming week. On the back side of
this ridge...the middle Ohio Valley will be under the influence of
moist southwesterly flow Tuesday into Wednesday. The combination of
this and a series of short waves lifting northeast over the ridge
will lead to a decent chance of showers and thunderstorms through
middle week. The East Coast ridge will begin to break down through the
end of the week with the flow aloft becoming a bit more zonal. This
will allow for some additional short wave energy to progress east
across the region with a chance of precipitation persisting through the end
of the long term period. Seasonably warm temperatures are
expected...with highs mainly in the lower 80s and overnight lows in
Aviation /02z Sunday through Thursday/...
surface high pressure centered off the East Coast will keep a dry
southerly flow over the Ohio Valley through the weekend. Generally
expect VFR conditions through the taf forecast period. In warm air advection pattern
expect high clouds with an increase in middle level clouds late
tonight into Sunday morning. These middle level clouds will pivot
north and thin out during the morning. Only expect few to scattered
cumulus clouds around 5000 feet Sunday afternoon.
Light southeast winds at less than 10 kts overnight will veer to the south
around 10 kts Sunday.
Outlook...thunderstorms with MVFR ceilings/visibilities possible Monday