Tornado Warning 42, NWS New Orleans, LA

Area Forecast Discussion
National Weather Service New Orleans LA
519 AM CDT Mon Jul 27 2020

.SHORT TERM...

Unsettled pattern will persist through at least Tuesday with PW
values continuing to be well over 2 inches as weak disturbances
rotate around Bermuda high in the northern Gulf. This along with
an upper level Low over central and western portions of LA will
bring increased lift and instability into the area with locally
heavy rainfall possible throughout the daytime hours today. The
heaviest rainfall is expected to occur during the morning and
afternoon hours with another day of drying conditions expected by
late afternoon and evening as atmosphere gets worked over with
little to no sunshine for recovery afterward. With that in
mind...temperatures will remain very pleasant again today with
highs only in the low to mid 80s. An expected repeat scenario
possible on Tuesday as little change in overall pattern expected.
Meanwhile...upper level trough will begin to drop into the western
Great Lakes beginning today. This will be the key to a break in
the current pattern. Upper level trough will move eastward towards
the northeastern USA by the middle and latter part of the week.
Upper level high pressure will expand and slowly drift westward
through the Gulf during the middle and latter part of the week
bringing a drying trend with conditions returning to more typical
summer conditions. Highs are expected to return to the lower 90s
by Thursday with increased sunshine and scattered afternoon and
evening thunderstorms.

.LONG TERM...
High pressure will remain in place over the central Gulf through
the end of the week. An upper level trough will drop out of
Canada near the upper Mississippi Valley and swing across the
Great Lakes region Wednesday, then shift east towards the
Atlantic. This will first push the upper ridge centered in the
western Atlantic southward. The CWA will be in an area of weakness
between that high pressure and another near the US Desert
Southwest. Towards the W/Th time frame, the far western side of
that Atlantic ridge will break off and become centered over the
eastern GOM. Depending on how strong that smaller ridge is will
determine home far it extends north and shields the local area
from rainfall. The current forecast does still contain chance POPs
as models haven't been particularly consistent with how much
subsidence develops locally. An unseasonably low latitude sharp
shortwave trough digs through the Arklatex and into the southern
Mississippi River Valley by the weekend. This will bring an
increased chance of thunderstorms into the area. A few storms
could be strong to severe over the weekend if this pattern hold
true.

&&

.AVIATION...
Heavy showers and isolated thunderstorms will continue to move
inland affecting all terminals by mid morning. A repeat of Sunday
will occur on Monday with prevailing light showers after 14z and
continuing through 23z. Winds have not been much of an impact but
IFR to LIFR ceilings can be expected as well as temporary
visibilities down to 1sm or less on Monday.

&&

.MARINE...
High pressure will remain over the eastern Gulf bringing a
continued onshore flow to the coastal waters through the period.
Winds will remain fairly light through the period with seas
remaining 3 feet or less through the remainder of the week.
Unsettled pattern to persist through the first half the week with
showers and thunderstorms...returning to more typical summer
weather pattern by late week with mainly nocturnal convection in
the offshore waters.

&&

.DECISION SUPPORT...

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  83  73  84  74 /  90  50  90  20
BTR  83  74  85  74 /  90  40  90  20
ASD  83  73  85  74 /  90  40  90  30
MSY  83  75  85  76 /  90  40  90  40
GPT  82  75  84  76 /  90  40  90  30
PQL  85  73  86  73 /  90  40  90  40

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&

Special Weather Statement
National Weather Service New Orleans LA
550 AM CDT Mon Jul 27 2020

LAZ046-049-056-057-271115-
Iberville-Ascension-Assumption-St. James-
550 AM CDT Mon Jul 27 2020

...A STRONG THUNDERSTORM WILL AFFECT ASCENSION...NORTHWESTERN ST.
JAMES...EAST CENTRAL IBERVILLE AND NORTHEASTERN ASSUMPTION
PARISHES...

At 548 AM CDT, a strong thunderstorm was located near Sorrento, or
near Gonzales, moving north at 15 mph.

Winds in excess of 30 mph are possible with this storm.

This storm is exhibiting some rotation and watching closely to see
if a tornado warning is needed. However, this storm doesn't appear
to have much of a wind risk outside of the 30 mph already mentioned
thus why a severe thunderstorm warning is not out right now.

Locations impacted include...
Gonzales, Donaldsonville, St. Gabriel, Sorrento, Port Vincent,
Prairieville, Geismar and Carville.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 3032 9117 3032 9114 3031 9112 3032 9110
      3032 9102 3033 9084 3006 9080 3004 9100
TIME...MOT...LOC 1048Z 174DEG 12KT 3014 9091

CAB

Special Weather Statement
National Weather Service New Orleans LA
624 AM CDT Mon Jul 27 2020

LAZ059-065>067-271200-
Lower Terrebonne-Upper Terrebonne-Lower Lafourche-Upper Lafourche-
624 AM CDT Mon Jul 27 2020

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN TERREBONNE AND
NORTHWESTERN LAFOURCHE PARISHES...

At 623 AM CDT, a strong thunderstorm was located near Houma, moving
northeast at 10 mph.

Winds in excess of 30 mph are possible with this storm.

This storm is exhibiting some rotation and watching closely to see
if a tornado warning is needed. However, this storm doesn't appear
to have much of a wind risk outside of the 30 mph already mentioned
thus why a severe thunderstorm warning is not out right now.

Locations impacted include...
Houma, Gray, Bayou Cane, Schriever and Raceland.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 2939 9084 2950 9092 2978 9078 2956 9046
TIME...MOT...LOC 1123Z 231DEG 9KT 2950 9074