Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus64 klix 142107 
afdlix

Area forecast discussion
National Weather Service New Orleans la
407 PM CDT Mon Oct 14 2019

Synopsis...

Current wind fields would indicate frontal boundary is just off
the coast, but moisture fields and radar returns would argue for
very close to the Interstate 10-12 corridor. Little in the way of
lightning currently over the cwa, and the main area of
precipitation appears to be shifting north somewhat. Areas where
the rain has been a little more widespread, such as Hammond,
McComb and Baton Rouge, have had trouble getting much past 70
degrees, while most other areas have been in the upper 70s and
lower 80s.

&&

Short term...

Precipitable water values remain high, around 2 inches, until
frontal system moves through the area around midday Wednesday. As
impulses move through the somewhat zonal flow across the Gulf
Coast, periods of rain and embedded thunderstorms will be
possible. Question will be where the heaviest rain focuses. With
the boundary expected to shift somewhat northward over the next 24
hours, threat of heaviest rain should primarily be to the north of
the local area. Can't rule out southwest Mississippi seeing a
couple inches of rain, though. With forecast cape values near
2000 j/kg tomorrow, a few strong storms are possible, but shear
and lapse rates weaker than one would like for severe weather.
Likely to categorical pops near and north of the boundary tonight
through tomorrow night and chance pops Wednesday morning. Dry and
cooler on Thursday.

Expect most or all of County Warning Area to be in the warm sector tomorrow, with
highs well into the 80s for most. Cooler air will arrive during
the morning Wednesday, with some southern locations reaching the
lower 80s for highs. Will go with a blend for lows Wednesday
night/highs Thursday, with most areas in the lower to middle 70s
for highs Thursday.

&&

Long term...

Front remains south of the area through Friday before returning
northward for the weekend. Biggest question for the weekend will
be the development of low pressure in the western Gulf of Mexico
in response to an upper wave moving eastward out of Texas Friday
night. European model (ecmwf) is somewhat more bullish on low pressure development,
and accordingly has higher rain chances and a stronger wind field
for Friday night and Saturday. Have undercut European model (ecmwf) pops somewhat,
but not as dry as GFS solution for those periods. Next frontal
passage just beyond the forecast period, late Monday night or
Tuesday.

Once boundary moves back northward Friday or Friday night,
augtober returns for late Saturday through Monday, with highs well
into the 80s Sunday and Monday.

&&

Aviation...

Currently, IFR to LIFR at kmcb, khdc and kbtr, where terminals
definitely north of the front. South of the front, conditions
trending toward MVFR ceilings, although there are occasional
improvements to VFR. Any thunder this afternoon should be limited
to khum, knew and kmsy, with threat diminishing after sunset.

While front is expected to get pulled north somewhat, terminals
north of the front should see ceilings and visibilities lower to,
or remain low end MVFR to IFR overnight. Should then see an
improvement in ceilings beyond 15z Tuesday. Redevelopment of
precipitation during the late morning and early afternoon on
Tuesday, with somewhat better chances for thunderstorms and rain during the
afternoon

&&

Marine...

Onshore flow should return to coastal waters this evening where it
isn't already occurring as boundary moves northward. Flow will
remain onshore until frontal passage on Wednesday, with exercise
caution headlines likely to be necessary as cold advection kicks
in Wednesday night. Should just be a brief period into early
Thursday. Question then becomes strength of low pressure mentioned
in long term portion of the discussion. For now, will paint winds
in the 15 to 20 knot range, but if current European model (ecmwf) solution
verifies, wind forecast will need to be bumped up later.

&&

Decision support...

Dss code: blue.
Deployed: brief deployments to support city of New Orleans for
building collapse.
Activation: none.
Activities: forecast support to city of New Orleans for building
collapse.

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; marginal risk severe or excessive rain.
Yellow = heightened impacts with short-fused watch, warning or
advisory issuances; radar support for slight risk severe
or excessive rain.
Orange = high impacts; enhanced risk severe; nearby tropical events;
hazmat or other large episodes.
Red = full engagement for moderate to high risk of severe and/or
excessive rainfall, or direct tropical threats; events of
National significance.



&&

Preliminary point temps/pops...
mcb 66 82 66 74 / 60 80 80 40
btr 71 84 69 75 / 60 70 70 40
asd 69 86 68 81 / 40 60 70 50
msy 75 87 74 81 / 30 50 50 50
gpt 71 83 71 79 / 30 60 70 50
pql 69 85 69 81 / 30 60 70 50

&&

Lix watches/warnings/advisories...
la...none.
GM...none.

National Weather Service Glossary of Abbreviations