Scientific Forecaster Discussion
fxus64 klix 131002
Area forecast discussion
National Weather Service New Orleans la
402 am CST Wed Dec 13 2017
an upper level trough that dove into the southeastern conus
yesterday will gradually lift east over the next couple days. This
will allow for zonal flow to devlop over the local area. Continental
airmass thats already in place from cold front that moved through
yesterday will be slow to modify. Temperatures today will not be
much different from yesterday...still below normal. Its not until
Thursday, when 500mb heights increase from zonal flow developing,
that highs moderate into the mid/upper 60s.
A cold front will be moving through Friday morning as a somewhat
weak upper trough swings across the Mississippi Valley. The sub-
tropical jet will be carriing Pacific moisture across Mexico to the
northern Gulf Coast as this front moves into the Gulf. It appears
the timing of this moisture will be such that showers don't develop
along the front until it reaches the coast. So, have kept pops
mainly restricted to areas from New Orleans southward.
Models show a cutoff stuck over the baja of California late this
week, getting pickup and racing northeast this weekend as another
trough drops into The Rockies. Numerous showers and a few
thunderstorms are likely to develop as frontogenesis takes place.
The European model (ecmwf) is faster than the GFS in regards to rainfall beginning
and ending, but otherwise models are in fairly good agreement. Model
soundings indicate quite a saturated column but with ample winds
aloft. This would suggest minimal instability for severe storms but
a few may be strong with downbursts possible.
The boundary will likely stall along the northern Gulf Coast as
troughing is maintained west of the County Warning Area. This will lead to bouts of
rain moving across the area. Its not until the middle of next week
that the base of the trough finally shifts east and flushes the
VFR through taf cycle.
Winds will lower further this morning but rise once again by late
this afternoon mainly for the open Gulf waters ahead of the next
front expected in the area Friday morning. Winds could get up to
around 15kt ahead of the front and 15 to 20kt behind the front
Friday morning. This front will stall over the central Gulf Friday
night becoming a warm front then rapidly move north inland Saturday.
The next cold front will advance to the central Gulf Sunday and
should move through by that evening. This front may stall for a
short time over the Gulf before a reinforcing surge of high pressure
forces the front farther away. This progressive pattern will set up
a fast paced roller coaster with wind speeds and directions. Onshore
flow will get up to 15 to 20kt ahead of each front while northerly
winds behind each front will do the same.
dss code: green.
Decision support services (dss) code legend
green = no weather impacts that require action.
Blue = long-fused watch, warning, or advisory in effect or
high visibility event.
Yellow = heightened impacts with short-fused watch, warning or
advisory issuances; radar support.
Orange = high impacts; slight to moderate risk severe; nearby tropical
events; hazmat or other large episodes.
Red = full engagement for moderate risk of severe and/or
direct tropical threats; events of National significance.
Preliminary point temps/pops...
mcb 60 40 63 36 / 0 0 0 10
btr 62 41 65 38 / 0 0 0 10
asd 61 43 66 40 / 0 0 0 10
msy 63 47 66 44 / 0 0 0 10
gpt 60 45 64 42 / 0 0 0 10
pql 61 42 66 40 / 0 0 0 10