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fxus64 kshv 181747 

Area forecast discussion
National Weather Service Shreveport la
1147 am CST Mon Dec 18 2017

foggy conditions have slowly improved at the terminals late this
morning, with metar reports of VFR-IFR vis, though IFR-LIFR ceilings
continued to plague the terminals. Visible is anticipated to continue
to improve throughout the afternoon though patchy fog may linger,
whereas the ceilings will remain low. Shortly after sunset, visible will
deteriorate back to IFR to possibly LIFR criteria whilst chances
for -shra commences to near klfk /perhaps as early as late this
aftn/. -Shra will spread northward to the remaining terminals this
evening into tonight, with increasing instability leading to the
potential for thunderstorms in the vicinity. Have tried to insert the correct time-frame at
each terminal for the onset of precipitation. Otherwise, light
east-southeast winds will veer a bit to the south-southeast
throughout the taf cycle.


Previous discussion... /issued 1044 am CST Mon Dec 18 2017/

the dense fog advisory was allowed to expire at 16z as
visibilities have improved considerably, but patchy fog still
remains. Pops were tweaked a bit as the latest regional radar
loops show most of the rain is still well south of the region.
Based on latest hi-res guidance, the higher rain chances were
shifted back to the west into our far southwest zones in deep East
Texas. The best vertical ascent should be closer to the developing
surface low and warm front. Temperatures for today were also
raised by a few degrees. The fog has dissipated earlier today
compared to yesterday, and temperatures are already warming into
the 50s in many locations. However, guidance was still undercut by
several degrees.

Updated text products have been sent.


Previous discussion... /issued 514 am CST Mon Dec 18 2017/

dense fog continuing across most of the area along and south of
I-20. Low clouds and patchy fog will likely continue into the aftn
under a stg low lvl inversion. A warm front near the coast with
dewpoints in the lower 70s over the Gulf waters will begin pulling
rich moisture onshore with pcpn water values nearing 2 inches,
very unseasonally high. This slow movg warm front will reach near
the Interstate 20 corridor by Tue aftn with very heavy rain near
this frontal boundary. Two to four inches of rain may occur where
this boundary begins to stall. Very stg low lvl shear may also
cause a few tstm cells to become stg and produce gusty winds.
The vigorous upper low will pass east of the area durg the day
Wednesday with quiet wx expected under the approach of deep long
wave trough bringing continued southerly flow and fairly warm
temps. Convection will likely remain scattered in the warm sector.
Models still have not come into agreement with either the arrival
of the much colder Arctic airmass, or the amount of moisture as
the colder air arrives. A wintry mix is possible across the
northern edge of the area in the stratiform rain behind the front
although will keep pops isold for now with no accumulations
expected. Finally, the GFS suggests a brief period of light snow
movg across OK well into the cold air mass with the entire column
of air sub freezing late Sat night into sun mrng.



Preliminary point temps/pops...
shv 56 53 68 57 / 10 50 90 90
mlu 57 50 71 60 / 10 20 70 90
deq 56 48 65 53 / 0 30 90 90
txk 55 50 65 56 / 10 40 90 90
eld 55 49 67 55 / 10 40 80 90
tyr 58 55 65 54 / 20 50 100 80
ggg 57 54 68 55 / 20 50 100 90
lfk 62 59 71 56 / 30 50 80 70


Shv watches/warnings/advisories...

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