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Area forecast discussion...updated 
National Weather Service Fort Worth Texas
1013 am CST Tuesday Dec 1 2015

there are no major changes for the update this morning other than
to formally remove the mention of light rain showers across far
southeastern zones. 12 UTC upper air analysis revealed that drier
air in the wake of the 925-850 mb front has already surged
southward through much of the County Warning Area this morning. Areas of patchy fog
continue to dissipate this morning and the only semblance of
sufficient moisture for any type of sensible weather has been confined
to the middle/upper levels of the atmosphere. This moisture will
continue to stream in from the southwest courtesy of the
subtropical jet as seen on water vapor imagery. A shortwave
trough...noted across The Four Corners region...will dive
southward towards north and central Texas later today and through
the overnight hours. This should help nudge the plume of upper
level moisture southward later this afternoon and into tonight.

Afternoon high temperatures appear reasonable and only adjustments to a
few of the hourly grids were necessary. Otherwise...the forecast
remains in good shape. All associated products have been updated
and sent.



/issued 539 am CST Tuesday Dec 1 2015/
/12z tafs/

VFR conditions expected to prevail through the period although
some thick cirrus will continue to stream in across the area
today. Skies will clear out later tonight as a weak front moves
into the area. Light northwest winds will prevail and strengthen a
bit early Wednesday morning.

Otherwise...some patchy dense fog is occurring across parts of
North Texas mainly west of the major airports. Visibilities may be
reduced to less than 1/2 mile at times but as of now it does not
appear that these lower visibilities will impact any of the major
airports. Will have a tempo for 4sm br at Alliance which tends to
cool off a little more than surrounding sites.



Previous discussion... /issued 342 am CST Tuesday Dec 1 2015/

Early morning water vapor satellite imagery showed a large upper
level low pressure system in place over the northern and Central
Plains. To the south and southwest of this upper low...a strong
upper level sub-tropical jet stream was observed from 00z radiosonde observations.
Water vapor and infrared satellite imagery shows that this strong
jet was transporting a steady stream of tropical moisture
northeast over the region from the subtropical Pacific Ocean.
Because of the high terrain of Mexico...this moisture was only
observed above the 400 mb level over the Southern Plains. This
resulted in a thick band of cirrus over the region early this
morning. At the surface...subjective analysis showed an
anticyclone centered just south of Wichita Falls early this
morning. Across north and central Texas...dew point depressions
were on the order of 0 to 3 degrees f.

Today...the surface high/anticyclone is expected to move slowly
east across the County Warning Area today. Light and variable winds were primarily
relegated to locations along and north of Interstate 20 and west
of Interstate 35 as of 3 am. Light northerly winds were observed
across the remainder of north and central Texas...a bit farther
away from the surface high. Despite the high low-level humidity
and light winds...only patchy fog was observed across the region
so far this morning. The thick cirrus over the region is likely
helping to keep temperatures from falling by radiating infrared
radiation/heat back to the surface.

Because we were already very close to saturation at many
locations along and west of Interstate 35 already this
morning...we may still see more fog development before sunrise.
Went ahead and kept patchy fog in the forecast along and west of
Interstate 35 this morning to account for this. Will monitor the
fog development this morning and if fog becomes more prevalent...
will update the forecast to include dense fog and may issue a
dense fog advisory if needed. As it is think that with the cirrus
holding in place all morning...any dense fog will remain
patchy/isolated in nature.

A shortwave trough over the northwestern Continental U.S. Is expected to move
southeast today and help kick the upper low east from the northern
and Central Plains towards the Great Lakes region. This will send
a band of lift over north central Texas today and tonight. Early
this morning...regional radars showed a band of isolated rain
showers extending just northwest of Houston off to the northeast
over northern Louisiana and across Mississippi. This band of
showers appears to be associated with lift in the 850 to 700 mb
layer. This band of lift will likely continue today...and may even
be enhanced by the upper level support provided by the large upper
low moving east this afternoon and evening.

At this time kept rain showers out of the forecast for locations
along a Palestine to Temple line as it looks like dry air has
already worked its way southeast across these areas in the wake of
yesterday's rain shower and thunderstorm activity. Think that we
will see some relatively strong lift over these areas later
today...but forecast soundings indicate that the air is so dry in
the middle troposphere that the development of rain showers is
unlikely. Left a 10 pop in place with no mention of showers at
this time. Will monitor this region for rain showers this
afternoon and evening just in case the middle-levels are not as dry
as forecast soundings indicate. However all available model
guidance is in line with dry middle-levels across central
confidence in a dry forecast is fairly high at this time.

Wednesday through the upper low continues east is expected to send another cold front southeast
across north and central Texas on Wednesday. This will send a
reinforcing shot of dry air across the region...and will nudge the
subtropical jet south and east. The end result will be at least a
few days of mostly clear/sunny skies across the region. Overnight
temperatures may fall below freezing Wednesday and Thursday
mornings as clear skies allow for ideal radiational cooling with
dry air in place. Have most of the urban areas holding above
freezing at this time...but this may change depending on how cool
we get behind wednesday's cold front. Upper level ridging is
expected to hold over the region through Saturday which should
allow enough sunshine for highs to climb into the upper 50s by the
end of the week.

Another upper level storm system is expected to move over the
Southern Plains on Sunday. Confidence is fairly high that this
system will spread strong lift over parts of north or central
Texas...however moisture return and availability is the biggest
source of uncertainty. Wednesday's front is expected to advect dry
air over much of the Gulf of Mexico. A persistent surface ridge
over the eastern Continental U.S. Will keep low-level winds over the Gulf out
of the east or northeast. This will limit the potential for deep
moisture to return to North Texas out ahead of sunday's upper
level trough/storm system. Kept 20-30 probability of precipitation in place for now
assuming that the strong lift will be sufficient for at least some
isolated rain showers as it moves across the region. Will continue
to watch how models treat the winds over the Gulf in the week
ahead as this appears to be the main factor inhibiting more
widespread rainfall chances.

Shortwave ridging is expected over the region on Monday...
followed by another compact upper low moving over the region on
Tuesday. Moisture looks even more limited out ahead of the Tuesday
upper even if models are correct on the strength and
timing of this feature...rainfall appears to be unlikely at this



Preliminary point temps/pops...
Dallas-ft. Worth, Texas 55 38 56 36 57 / 5 5 5 5 0
Waco, Texas 57 39 58 33 59 / 10 5 10 5 5
Paris, Texas 55 36 52 34 56 / 10 5 5 5 5
Denton, Texas 54 33 55 31 56 / 5 5 5 5 0
McKinney, Texas 55 35 54 33 56 / 5 5 5 5 0
Dallas, Texas 56 38 56 37 57 / 10 5 5 5 0
Terrell, Texas 56 38 55 34 56 / 10 5 5 5 5
Corsicana, Texas 56 42 57 36 57 / 10 5 10 5 5
Temple, Texas 57 39 59 35 59 / 10 5 10 5 5
Mineral Wells, Texas 55 34 56 30 58 / 5 5 5 5 0


Forward watches/warnings/advisories...



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