Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Fort Worth Texas
552 PM CST Tuesday Dec 1 2015
No concerns...VFR with north flow.
As the cirrus plume shifts south...clearing skies at long last...
a cold front will invade from the north. Speeds will be primarily
under 12kts...but during the day Wednesday...some higher speeds
may mix to the surface.
a tranquil weather pattern can be expected through a majority of the
forecast period with temperatures slowly moderating each day into
the weekend. Low chances for light rain return late in the
weekend as the next upper level low moves through the region.
Thereafter...dry conditions appear likely.
Short term /tonight through Thursday/...
dry conditions can be expected through all of the short term
forecast period as middle and low level moisture will remain quite
scarce for any sort of precipitation. For tonight...a shortwave
trough will continue to dive southward around the main upper low
that is currently producing snowfall across the upper Midwest and
Great Lakes region. The shortwave trough will influence the
weather across north and central Texas in two ways. First...the
upper level trough will usher in northerly winds aloft which will
help to nudge the conveyor of middle/upper level moisture further to
the south. This should result in a gradual clearing of the dense
cirrus canopy from north to south through the day on Wednesday
morning. Second...this upper level trough will help to push a
cold front...albeit weak and dry...south into the area on
Wednesday morning. The winds associated with this feature may be
enough to prevent most areas from falling below freezing as
sufficient momentum Transfer occurs in the low levels to prevent
the boundary layer from completely decoupling. Of course...if
winds decrease behind the front...temperatures will fall below
current forecast values.
Wednesday through Thursday look to both be fantastic days with
regards to afternoon high temperatures as middle level height rises
in the wake of the aforementioned trough overspread the region.
The implied subsidence should also result in rain-free conditions
across all of north and central Texas. Light north winds can be
expected across much of the area as surface high pressure re-
builds across the region. Overnight low temperatures for Wednesday
evening into Thursday morning will be on the cold side as clear
skies and generally light winds will optimize the radiational
cooling potential. As a result...the current forecast undercuts
MOS guidance by a couple of degrees. In addition...the current
forecast will also mention the potential for patchy frost across
all of north and central Texas during this time period as grounds
remain wet from recent rainfall...winds become light and
temperatures are expected to fall into at least the middle 30s.
Thursday should be a tad warmer than Wednesday as surface high
pressure slides off to the east. Western zones will be the first
locations to see a slow wind shift to the south on Thursday and
thus will likely see the warmest conditions in the afternoon.
Temperatures will climb into the low to perhaps even middle 60s
across these areas. Light north to northeast winds elsewhere will
support temperatures in the middle to upper 50s and to near 60
degrees due to the weak cold air advection. Thursday night/Friday
morning temperatures should remain in the middle to upper 30s across
much of the area with a continued potential for patchy frost.
Long term /Friday through Monday/...
for Friday...a few high clouds may stream in from the northwest as a
weak perturbation ripples through the northerly flow aloft. While
some weak lift may be present with this feature...forecast profiles
across the region suggest that the atmosphere will be too dry to
support any precipitation chances. With the continued southerly
low level flow across all of north and central Texas...high
temperatures should continue to moderate such that most areas
climb into the upper 50s and low 60s....despite the cirrus clouds.
For Saturday...additional high clouds will filter in from the west ahead
of the next upper trough that is forecast to swing through the
region. High temperatures will be a few degrees cooler than the
previous days due to the thicker cirrus...but readings in the middle
to upper 50s can still be expected.
With regards to the rain chances Saturday evening into Sunday
morning...most of the 12 UTC model guidance has trended slightly
drier. Middle-level 12 hour height falls on the order of 50 meters are
expected to overspread central Oklahoma on Sunday and with North
Texas beneath the right rear quadrant of a 50-60 knots middle level
jet...lift should be aplenty. With the continued saturation of the
upper levels and slow moistening of the low levels in response to
low level warm air advection/moist advection...there should at least be an
increase in some low cloud cover. Closer examination of forecast
profiles however reveals that the middle-levels will remain quite
parched. As a result...have lowered probability of precipitation a bit during this time
period and will only carry a mention of sprinkles or very light
rain in the worded forecasts. At this time...it appears that rain
amounts will be quite light and the best chances for measurable
precipitation will initially be confined to areas north of the
Highway 380 corridor. The low rain chances will then shift to
areas along and east of the Interstate 35/35w corridors as a cold
front slides through the region on Sunday morning and afternoon.
Dry conditions appear likely towards the beginning of next week as
ridging in the wake of the aforementioned trough dominates.
Preliminary point temps/pops...
Dallas-ft. Worth, Texas 38 56 35 57 36 / 5 5 5 0 5
Waco, Texas 39 60 33 59 33 / 5 10 5 5 5
Paris, Texas 36 52 32 56 35 / 5 5 5 5 5
Denton, Texas 33 54 32 58 32 / 5 5 5 0 0
McKinney, Texas 35 53 32 56 33 / 5 5 5 0 5
Dallas, Texas 38 55 35 57 39 / 5 5 5 0 5
Terrell, Texas 38 55 33 56 35 / 5 5 5 5 5
Corsicana, Texas 40 57 35 57 37 / 5 10 5 5 5
Temple, Texas 39 60 35 59 34 / 5 10 5 5 5
Mineral Wells, Texas 34 56 32 59 33 / 5 5 5 0 5