Area forecast discussion
National Weather Service Fort Worth Texas
347 am CDT Sat may 25 2013
Discussion...
radar/satellite loop indicates that the weak middle level low is
likely located near Abilene and 00z 500mb analysis confirms it is
warm-core in nature. As is often the case with warm-core
lows...convection is firing before sunrise across The Hill
Country within a weak low level jet axis where Theta-E advection
and orographic lift are occurring. Short-term models such as the
hrrr and RUC suggest that scattered convection will continue to
expand northward from central Texas into the western zones during
the morning hours. The GFS appears to be suffering from grid scale
convective feedback which is resulting in very high quantitative precipitation forecast and
contaminated mass fields...thus the GFS will not be used in the
short-term. The NAM seems to be matching current trends and short-
term models well and therefore it gives confidence to raise probability of precipitation
today. We expect the best coverage of convection in the western
zones this morning. Scattered convection will build/expand
eastward into the eastern zones during the midday/afternoon hours.
The airmass over the eastern zones will be a bit more unstable due
to better insolation and a couple of strong storms with gusty
winds will be possible...but due to weak shear the severe threat
is low. Highs today in the western zones will only be in the upper
70s to low 80s due to clouds/rain...with highs in the eastern
zones reaching the middle 80s. Scattered convection will continue
into the evening hours before dissipating with loss of heating.
The warm core middle level low will be exiting the region to the
northeast tonight...and therefore the rain chances will come to an
end. Expect a dry Sunday with temperatures rebounding into the
middle-upper 80s area wide. As an upper level trough develops across
the inter-mountain west...a surface low will deepen in the High
Plains Monday. This will bring breezy south winds to the region
Monday which will likely persist through the week. Low temperatures will
warm into the 70s area wide by midweek with highs generally in the
middle 80s east to low 90s west. The southwest flow above the
surface will bring a thermal inversion into the area. Thus the
forecast looks dry unless/until forcing arrives to weaken the cap.
Model guidance remains in poor to fair agreement regarding the
evolution/ejection of the West Coast upper trough middle-late week.
The European model (ecmwf) continues to show a very negatively tilted trough
swinging through the region late Wednesday and Thursday which
would Bode well for rain. But it continues to be the only model
that shows the trough ejection like this...and frankly the 500mb
pattern it presents just does not look realistic. If it were not
for the European model (ecmwf) being the better of the long range models...I would
discount it altogether and show a dry forecast on Thursday...but
for now have retained the slight chance probability of precipitation. The GFS/UKMET/Gem
forecasts show that the upper energy needed to break the cap will
likely remain well northwest of the region. Furthermore...the
dryline also looks like it will remain too far to the west...with
the GFS showing it as far west as the Texas Panhandle. Storm motions
will generally be northeast and this means storms would not even
have a chance to propagate into the County Warning Area either. So in summary the
rain chances on Thursday at this point are hinging on the European model (ecmwf)
being correct...and this may be a bit of a long shot.
Tr.92
&&
Preliminary point temps/pops...
Dallas-ft. Worth, Texas 84 69 87 69 87 / 40 30 10 5 0
Waco, Texas 83 68 87 68 89 / 50 30 10 5 0
Paris, Texas 83 67 85 66 85 / 30 30 10 5 0
Denton, Texas 85 67 86 68 87 / 40 30 10 5 0
McKinney, Texas 84 67 85 68 87 / 30 30 10 5 0
Dallas, Texas 85 71 87 70 89 / 30 30 10 5 0
Terrell, Texas 84 67 86 68 88 / 30 30 10 5 0
Corsicana, Texas 84 67 88 68 89 / 30 30 10 5 0
Temple, Texas 82 67 87 68 88 / 50 20 10 5 0
Mineral Wells, Texas 81 66 87 67 89 / 40 20 10 5 0
&&
Forward watches/warnings/advisories...
none.
&&
$$
