Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Fort Worth Texas
1144 am CST Friday Nov 27 2015
the terminal forecasts will be generally unchanged for the next 24
to 30 hours across north and central Texas. IFR to MVFR ceilings
will persist for the afternoon hours before conditions diminish
after 00z to generally IFR conditions with thunderstorms. Have
been watching West Texas and New Mexico this morning...where
lightning strikes have been ongoing...signifying an intense
shortwave moving through the southwest flow. Expect another round
of thunderstorms to develop after 00z...and last through much of
the overnight hours. Will be on the watch for additional updates
as the bands of thunderstorms or heavy rainfall move through.
cold front has made it through all but our extreme southeast
counties this morning with temperatures falling 25 to 30 degrees
behind the front. Widespread rainfall continues atop the shallow
cold air but rain rates have generally decreased. Heaviest rates
are around 1/2 inch per hour but many areas have picked up 4 to 6
inches of rain already...so flooding will continue to be a
significant concern. Activity is still scattered in nature with
breaks in the overall coverage but more persistent moderate
rainfall is expected to occur later this afternoon into tonight.
Water vapor imagery shows the upper low across the southwest U.S.
With strong southwest flow into the Southern Plains. In addition
the upper level influences of Hurricane Sandra are starting to
spread into Texas. We should see a gradual strengthening of the
upper level winds and increasing diffluence across North Texas
through tonight. This coincides well with increasing isentropic
ascent across the northwest half of the County Warning Area as the 850mb front
will be slowly moving into that area. Strong pressure advection on
the 295 and 300k potential temperature surfaces across the
northwest counties will persist into the overnight hours and
likely represents the area of heaviest rainfall over the next 24
No major changes to the current forecast...other than to tweak
hourly temperatures and make some minor adjustments to forecast rainfall
Previous discussion... /issued 432 am CST Friday Nov 27 2015/
today through Sunday...today is not going to be a pleasant day
across most of north and central Texas as cold and rainy
conditions persist. The cold front is ahead of schedule and
steadily advancing southeast across the region this morning. At
330 am the front was along a line from Bonham to near Dallas to
Goldthwaite. The front will slow its eastward progression some
today but should be entirely through our southeastern counties by
Temperatures behind the front are quickly falling into the 40s
while temperatures ahead of the front remain in the 60s and lower
70s. Temperatures will steadily fall throughout the day today and
it will feel much cooler with a strong north wind behind the front
resulting in lower wind chill values. High temperatures today are
a little misleading as most locations across the western and
northern halves of the County Warning Area will experience their high temperatures
early this morning with falling temperatures nearly all day.
The first main wave of precipitation has largely moved northeast
out of our County Warning Area but continued widely scattered activity will occur
this morning ahead of and behind the front. The precipitation
behind the front is due to warm moist air being lifted over the
shallow cold dome near the surface. Another widespread round of
precipitation is expected to traverse the area this afternoon.
Some of the models are developing this next round of moderate to
heavy rain this afternoon while about half of the models keep just
scattered activity in the region.
Closer analysis shows strong lift should occur near the 850-700
mb fronts across our northwestern counties as this region would
ideally be the forcing mechanism for the next round of rain.
Therefore...will keep high probability of precipitation across roughly the northwestern
half of the region this afternoon and also increase rain amounts
over the previous forecast. This next round of rain will push off
to the northeast this evening/tonight and then the next round of
rain looks to be right on its heels occurring late tonight.
The heaviest rains with the round of rain late tonight /technically
the third round/ will be across roughly the northwest half of the
Across the southeast half of the region...periods of moderate to
heavy rain are expected this afternoon and evening with a tapering
off of the overall activity tonight. Overnight the rain will
likely be more scattered in nature but just about everyone is
expected to receive rain today and tonight.
Temperatures tonight will fall close to 32 degrees in some
locations in our western and northwestern zones. We still do not
expect any freeing rain or winter precipitation in our area but it
is possible that if the rain stops and temperature do fall to 32
degrees...some water could freeze on elevated surfaces.
However...impacts to travel are not expected.
Latest guidance suggests we should start to see a decrease in the
rain activity late Saturday but there could be one final round of
more widespread rain late Saturday night/early Sunday. The rain
will end from west to east on Sunday but it isnt entirely over for
the week. More on that in a bit but no changes are needed to the
Flash Flood Watch. Additional rainfall totals are still forecast
to be highest within the watch area where an average of 4-7 inches
is expected with some higher amounts possible from the dfw area
to the north and northeast. Across our southern counties in
central Texas...rainfall totals of 2-4 inches can be expected with
isolated higher amounts.
Below normal temperatures will persist through the weekend with
small diurnal trends each day due to the rain...cold air
advection and dense cloud cover. Temperatures will finally start
to warm a little more significantly by Monday.
Monday through Friday...will keep low probability of precipitation mainly south of
Interstate 20 Monday through Wednesday. During this period we will
remain under the influence of southwest flow aloft as an upper
level trough develops to our west. The moisture across central
Texas and our southern counties will not be completely scoured out
and some weak large scale lift over the region from the
approaching trough may aid in the development of isolated to
scattered showers and possibly a few thunderstorms south of
Interstate 20. This rain activity is not expected to be heavy and
at this time is not expected to cause additional flooding
concerns. The upper level trough will swing through the state on
Wednesday and Thursday bringing an end to the rain chances through
at least Friday.
with the rain at dfw Airport yesterday and early this
morning...2015 is now the wettest year ever on record at dfw
Airport. The previous record was 53.54 inches set in 1991. As of
420 am CST...dfw/S yearly rainfall total is now 54.75 inches.
Also...dfw has already broken the daily rainfall record for
today...November 27th. The previous record was 0.76 inches in
1958. The daily total so far as of 425 am is 1.29 inches.
With the rain Waco received yesterday and so far this
morning as of 425 am...the yearly total at Waco Regional Airport
is now 47.63 inches. This makes it the sixth wettest year on
Preliminary point temps/pops...
Dallas-ft. Worth, Texas 48 39 41 39 46 / 100 100 100 100 80
Waco, Texas 69 40 42 40 46 / 100 80 80 90 80
Paris, Texas 66 42 45 41 49 / 100 100 100 100 80
Denton, Texas 44 38 39 38 44 / 100 100 100 90 70
McKinney, Texas 49 39 41 39 46 / 100 100 100 100 80
Dallas, Texas 50 40 42 39 46 / 100 100 100 100 80
Terrell, Texas 57 41 43 40 47 / 100 100 100 100 80
Corsicana, Texas 70 43 44 42 47 / 100 80 80 90 80
Temple, Texas 72 40 42 40 46 / 100 70 70 80 70
Mineral Wells, Texas 42 35 37 36 42 / 100 100 100 90 70
Flash Flood Watch through late Saturday night for txz091>095-