Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
FXUS64 KLIX 290052
Area Forecast Discussion
National Weather Service New Orleans LA
752 PM CDT WED SEP 28 2016
Drier air has been slowly moving southward over the area today and
this has caused our precipitable water (PW) value to drop from
1.95 inches this morning to 1.32 inches this evening. Based off of
19z NUCAPS data and latest water vapor imagery, it`s likely that
not everywhere has had a drop in their PW just yet. 19z NUCAPS
near Slidell had a PW of 1.16 inches while near Galliano the PW
was 1.74 inches. The drier air will eventually make it to all
coastal areas as the water vapor imagery shows the drier air
roughly from a Baton Rouge-New Orleans-Boothville line continuing
to slowly drift southward. Otherwise, the boundary layer is well
mixed and extends to almost 4000 feet. Winds throughout much of
the troposphere are from the northwest with the exception of some
winds from the west in the low levels. A peak wind speed of 85
knots was at 35000 feet.
00z balloon info: A successful flight ascending for 105 minutes
reaching a height of 20.5 miles above the ground bursting over
Lake Borgne 28 miles downrange from the office.
.PREV DISCUSSION... /issued 314 PM CDT WED SEP 28 2016/
Through Saturday, deep layer northwest flow and strong subsidence
throughout the atmospheric column will dominate the Gulf South.
This pattern will keep a very benign weather pattern in place
across the region with clear skies, low humidity, and below normal
temperatures expected. Continued cold air advection should peak
out on Friday when the heart of a 925mb cold pool will be directly
over the region. This will result in the coldest temperatures
occurring on Friday with overnight lows dipping into the 50s and
lower 60s and daytime highs only rising to around 80 degrees.
Both Thursday and Saturday will also see below normal
temperatures, but temperatures should be 3 to 5 degrees higher
than on Friday.
Heading into the first half of next week, both models agree that
an elongated and weak upper level trough should be in place
across the eastern Gulf of Mexico with some ridging positioned over
the Southern Plains. This overall pattern is expected to keep a
moisture gradient in place across the forecast area with higher
mixing ratios and precipitable water values over the eastern
coastal waters, coastal Louisiana, and coastal Mississippi. The
forecast has isolated to widely scattered showers and
thunderstorms in place for these areas beginning on Sunday and
then persisting through Tuesday. Increased subsidence and drier
air across Southwest Mississippi and the remainder of Southeast
Louisiana should keep rain chances below 10 percent through
Tuesday. At most, an increase in cloud cover is expected for these
areas early next week. Temperatures will also gradually modify as
moisture begins to advect in from the central Gulf. Overall,
expect temperatures to rise back to what is normally seen this
time of year with lows in the 60s and highs in the middle 80s.
A negatively tilted trough moving through the Plains states is
forecast drive a weak frontal boundary toward the area on
Wednesday. This front should serve as a focus for scattered shower
and thunderstorm activity especially over northwest zones
Wednesday afternoon. Temperatures should also continue to warm as
southerly flow increases in advance of the front. Daytime highs
should rise back into the upper 80s and lows should climb closer
to 70 degrees.
VFR conditions will persist at all terminals through the forecast
Moderate offshore flow as continental airmass continues to
slowly but steadily build into the north gulf through Friday.
General NE to E flow to maintain through Tuesday. 24/RR
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 61 81 54 79 / 0 0 0 0
BTR 63 83 55 80 / 0 0 0 0
ASD 63 84 54 80 / 0 0 0 0
MSY 71 84 64 80 / 0 0 0 0
GPT 65 85 59 80 / 0 0 0 0
PQL 63 85 55 80 / 0 0 0 0