Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Fort Worth Texas
551 am CST sun Nov 23 2014
the clearing line was oriented from just east of Waco to dfw as of
530 am. Ftw...afw...gky and act should remain clear through the
morning with VFR conditions...except for some temporary visibility
restrictions at act through 13z. Dfw and Dal will see temporary
vlifr conditions through about 13z before clearing. Have opted to
handle the IFR conditions with a tempo group at dfw since IFR
conditions should most likely be gone by 1230z. Dal should clear
around 13z based on linear extrapolation of the clearing line. VFR
conditions will prevail through the remainder of the taf period at
all North Texas terminals.
The only other concern today/tonight will be a strong and gusty
west to northwest wind behind a cold front. Initially winds will
be south to southwest at speeds generally less than 12 knots. Once
the boundary layer fully mixes by midday some higher momentum air
will mix down and wind speeds should increase between 14 and 18
knots sustained from the west/southwest. Cross winds on
north/south runways should become an issue when the cold front
moves across the region between 21 and 23z. Frontal passage will turn the
wind to the west/northwest (around 310 degrees) and increase wind speeds
between 20 and 25 knots sustained with gusts to near 35 knots.
These strong and gusty winds will most likely continue beyond
sunset due to a tight surface pressure gradient behind the cold front.
Wind speeds should gradually decrease through the evening and fall
below 15 knots sustained around 06z.
Previous discussion... /issued 330 am CST sun Nov 23 2014/
the deep upper trough that was responsible for widespread rainfall
across North Texas yesterday is currently located south of the
area along the Texas coast. All of the rainfall has moved east of
North Texas this morning with some remnant cloud cover persisting.
Some patchy fog is also occurring in areas where winds have gone
calm and where there is a lack of high cloudiness. Otherwise...
partly to mostly cloudy skies prevail across North Texas with
temperatures in the middle 50s.
Water vapor imagery shows another upstream shortwave which is
moving through the intermountain west this morning. This feature
has already induced a Lee side cyclone over far southeast
Colorado. This is important for todays weather in North Texas
because as the upper trough digs into the Southern Plains...the
surface low will continue to deepen and move across central
Oklahoma. As it does...surface pressures will continue to fall
across North Texas...resulting in a tight gradient across the
region. These winds will primarily be westerly through middle
afternoon before becoming northwest as a cold front moves into
North Texas. The most significant concern today will be exactly
how high the winds get. With strong wind fields aloft associated
with the upper trough...any deep mixing could result in gusts
approaching 40 miles per hour. The latest GFS lamp guidance suggests that
this might happen...forecasting winds of 30g40kt at dfw late this
afternoon. This would cause some issues at area airports if it
pans out. The remainder of the guidance is not quite as aggressive
on winds...so will tone things down just a bit. Thinking is that
the highest winds will occur middle/late afternoon with the arrival
of the cold front. This is when lapse rates are steepest and there
is a good push of cold advection into the region. Current forecast
will show gusts approaching 40 miles per hour but this should be of short
duration as a surface inversion starts to develop after dark. We
will have a Wind Advisory for the northern half of North Texas
starting at 2 PM and continuing until 8 PM.
With westerly winds initially this afternoon...temperatures are
likely to warm considerably under mostly sunny skies. Will have
highs in the middle 70s across much of North Texas. Temperatures will be a
little cooler near the Red River.
Colder air will filter in behind the front this evening...so highs
on Monday will be 10 to 15 degrees cooler. A secondary front moves
in Tuesday with highs right around 60 degrees which is a little
below normal for this time of year.
Medium range guidance is in good agreement with a dry week ahead
and there is some indication that we will warm up rather nicely by
the end of the week. Broad ridging dominates the western U.S.
Wednesday through Friday with southwest flow aloft to about 700mb.
This suggests that temperatures will steadily climb through the
end of the week. GFS MOS numbers show highs reaching the middle 70s
by the end of the week. We wont go quite that warm yet but will
show highs warming into the upper 60s for Thanksgiving into Friday.
Preliminary point temps/pops...
Dallas-ft. Worth, Texas 77 41 63 39 62 / 5 0 0 0 0
Waco, Texas 77 43 64 35 61 / 0 0 0 0 0
Paris, Texas 74 40 59 34 58 / 10 0 0 0 0
Denton, Texas 75 38 61 35 60 / 5 0 0 0 0
McKinney, Texas 75 38 61 34 60 / 5 0 0 0 0
Dallas, Texas 77 41 63 39 62 / 5 0 0 0 0
Terrell, Texas 74 41 62 35 62 / 5 0 0 0 0
Corsicana, Texas 77 42 64 37 63 / 5 0 0 0 0
Temple, Texas 78 41 64 35 62 / 0 0 0 0 0
Mineral Wells, Texas 73 37 62 35 58 / 0 0 0 0 0
Wind Advisory from 2 PM this afternoon to 8 PM CST this evening