Forecast Discussion for Dallas/Ft. Worth, Texas

FXUS64 KFWD 170347 AAC

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
947 PM CST Sun Dec 16 2018

The forecast is in good shape with just a minor addition to the
weather grids needed tonight.

The plume of dense mid and upper level clouds continues to
infiltrate the region ahead of an upper trough situated across
Sonora and Chihuahua. Short term guidance has a good handle on
this and it`s likely that most of the area will stay socked in
beneath cloud cover through the overnight hours into Monday
keeping temperatures a few degrees warmer than the previous night.
Cloud cover may think some along the immediate Red River Valley
and this has implications for the fog forecast tonight. A very
diffuse boundary continues to slide southward through North Texas
at this hour. Outside of a subtle wind shift to the
north/northwest, the only real impact from this boundary will be
to help generate a reservoir of low level moisture that could lead
to some fog development. The most likely area where fog will
develop will be across the Ark-La-Tex where surface dewpoints are
a little higher with values in the upper 30s and low 40s. Forecast
profiles from the 3km NAM and RAP near Paris do support a good
chance for radiation fog and experimental visibility products
indicate that some of the fog may become dense. I`ve only added a
small sliver of patchy dense fog wording to parts of Fannin,
Lamar, Delta and Hopkins counties given that the lingering cloud
deck---though thinning---may keep T/Td spreads up a little higher
than I`d like to see for widespread dense fog. Nevertheless,
there still remains a chance that visibility reductions of 1/4
mile may occur...mainly in low-lying and sheltered
well as near bodies of water.

The rest of the forecast is in fantastic shape and updated
products have been sent.



.AVIATION... /Issued 605 PM CST Sun Dec 16 2018/
00 UTC TAF Cycle

Concerns---None major. Low MVFR vsby potential at DAL and GKY.

Dense mid and upper level cloud cover will continue to obscure the
Texas sky through the 00 UTC TAF cycle with cigs between FL150
and FL200. Across North Texas, light southerly breezes will become
westerly with a weak FROPA around 0300 UTC and this may
necessitate a flow change at D10 airports. Winds will turn more
northerly just after midnight with northerly breezes expected
through Monday evening. Across Central Texas, winds will be a
little slower to turn westerly and northerly with the windshift
likely closer to midnight. A sufficient reservoir of moisture is
expected to develop ahead of the front and may result in some
reductions in visibility. All indications at this juncture,
however, indicate that the probability of this occurring in the
Metroplex is NOT very high and I`ve refrained from including BR in
the TAFs. IF BR does occur at Metroplex TAF sites... DAL and GKY
would stand the best chances to see reductions in vsby given
their closer proximity to the near-surface moisture reservoir.



.SHORT TERM... /Issued 252 PM CST Sun Dec 16 2018/
/Through Tonight/

Widespread high clouds have streamed over the area today ahead of
a deepening southern stream upper low. Despite nearly overcast
skies through much of the day, temperatures have still managed to
climb into the mid 60s in most areas thanks to the return of
southerly winds.

Meanwhile, a slow-moving cold front lies to our north through the
Texas Panhandle and southern Oklahoma. Later this evening, a
shortwave swinging southward through the Central Plains will send
this very weak cold front into North Texas. This feature is
essentially just a surface trough, as there is little in the way
of cooler or drier air behind it. The only noticeable effect it
will have on sensible weather will be to turn winds to the west
and eventually to the northwest late tonight, but wind speeds will
remain fairly light. One side effect of this front will be the
potential for patchy fog to develop across portions of northeast
Texas Monday morning, likely just northeast of the DFW Metroplex.
Nearly calm winds and some pooled moisture should contribute to
at least some patchy fog development, although widespread fog may
be hindered by the presence of mid/high clouds which would inhibit
optimal radiation fog conditions. have included patchy fog in the
forecast for the time being, but localized dense fog is certainly
a possibility that will need to be monitored overnight.



.LONG TERM... /Issued 252 PM CST Sun Dec 16 2018/
/Monday through Next Weekend/

The disturbance currently over northern Mexico will lift northeast
across Texas on Monday, generating little more than increasing mid
and high level clouds along with the possibility of a few
sprinkles. It will also be accompanied by a weak cold front,
which will bring light northwest winds and knock a degree of two
off tomorrow`s high temperatures.

Return flow will quickly resume Monday night and Tuesday as a more
robust shortwave crosses the Four Corners region on its way east
towards the Plains. Between the two systems, light southeast winds
and mostly clear skies may allow for fog development during the
Monday night / Tuesday morning period. Patchy fog has hence been
added for the central and southeastern counties where the lesser
dewpoint depressions will be.

Scattered showers should begin to develop Tuesday late afternoon
or evening as the shortwave trough axis approaches from the west
and forcing for ascent increases over North and Central Texas.
The "evening" seems more likely due to the atmosphere being
initially starved of moisture as lift first arrives. PWATs will
eventually climb into the 0.85-1.0 inch range overnight Tuesday
night into Wednesday with the higher values east of the I-35
corridor. POPs will likewise be oriented with the highest in the
east. Instability will be limited, with surface-based CAPE values
of only a hundred or so forecast at this time, but mid level lapse
rates will be steep enough to warrant the mention of isolated

Precipitation will end across the western counties early
Wednesday, then move east of the entire forecast area by
Wednesday evening as the shortwave continues east.

The upper air pattern will amplify Wednesday night and Thursday
as another disturbance drops southeast through the Plains and
merges with the initial shortwave. The result will be a rapidly
deepening upper low over the Mississippi Valley on Thursday. This
will draw cool continental air farther south, and have sided with
the cooler end of guidance for the extended forecast temperatures.
At this time, it looks like all precipitation associated with the
upper low will remain east of the forecast area, and a dry
forecast will remain in place for late week into next weekend.



Dallas-Ft. Worth    42  59  42  65  50 /   0   0   0   5  50
Waco                43  62  39  65  49 /   0   0   0   5  40
Paris               40  58  42  61  47 /   0   0   0   0  50
Denton              38  57  39  65  48 /   0   0   0   5  40
McKinney            38  58  40  62  50 /   0   0   0   5  50
Dallas              43  59  43  65  50 /   0   0   0   0  50
Terrell             41  58  41  64  50 /   0   0   0   0  50
Corsicana           44  60  43  62  51 /   0   0   0   0  50
Temple              43  63  41  65  48 /   0   0   0   5  40
Mineral Wells       38  58  39  64  46 /   0   0   0  10  40





NWS FWD Office Area Forecast Discussion