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Area forecast discussion 
National Weather Service New Orleans la
1027 am CDT Sat Aug 23 2014

Update...
temperatures in most areas were running warmer than this time
yesterday. Dewpoint temperatures were slightly lower west to
northwest of Lake Pontchartrain...but slightly higher to the east
and south. Given these trends and after evaluating our heat
product criteria and the warm low temperatures experienced this
morning...we felt it was prudent to convert the excessive heat
watch to a heat advisory effective today through Sunday evening
for the Mississippi Gulf Coast counties and southeast Louisiana
parishes south of Lake Pontchartrain. Highs in these areas will
reach the middle 90s with warmer urban locations possibly reaching
the upper 90s...with heat indices rising to 105 to 108. Remaining
areas /west and north of Lake Pontchartrain into southwest
Mississippi/ will also be oppressively hot...but not quite as
humid today to meet heat advisory criteria...however...that should
change on Sunday as highs will soar to the upper 90s with heat
indices expected to reach 105 to 110. 22/dew point

&&

Decision support...
dss code...yellow.
Deployed...none.
Activation...none.
Activities...heat advisory...slurry support.

Decision support services (dss) code legend
green = no weather impacts that require action
blue = long fused watch/warning/advisory in effect or high
visibility event
yellow = heightened impacts with short fused
watch/warning/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 to high risk severe
and/or direct tropical threats; events of National
significance.

&&

Previous discussion... /issued 805 am CDT Sat Aug 23 2014/

.Sounding discussion...

The low-levels are quite moist on this morning/S sounding and we noted
a few thin patches of ground fog around launch time. There is
drier air from 850 to about 650mb before the midlevels moisten up
through about 400mb. Precipitable water values remain just a bit
above normal for this time of year at 1.95 inches. There is plenty
of instability with MLCAPE values around 3110 j/kg. With a trigger
temperature of 90 and a forecast high temperature off the sounding
of 96...we should have a few isolated thunderstorms today. No
temperature inversions exist outside of the typical low-level
inversion. Throughout the column...temperatures have changed
little at any given level from 24 hours ago. As for winds...a peak
wind of 31 knots was found at 8.4 miles above the ground.

12z balloon info: a routine launch with no issues with the flight
this morning. The balloon went 33 miles downrange and burst
southeast of Ponchatoula and reached a height of 20.5 miles above
the ground.

Ansorge

Previous discussion... /issued 406 am CDT Sat Aug 23 2014/

Short term...
only real issue for today will be warm temperatures and heat index
values in the 105-110 range most locations this afternoon. Per
local guidance and policy of utilizing the synoptic health watch-
warning network...which accounts for cumulative effect of
excessive heat...today will make day one of a moist tropical+
/mt+/ air mass. Sunday's temperatures will be indicated to be a
degree or two warmer than today and also make day two of mt+
conditions...worthy of an excessive heat watch. The models are
suggesting...for various reasons...some nocturnal rainfall moving
from the east into the forecast area Sunday night that would
effectively end the string of mt+ conditions. The NAM is
indicating a well established easterly wave that may actually be an
emanation of energy from invest 96l...the GFS is showing an impulse
rounding the fringe of the ridge from Alabama...through coastal
Mississippi into eastern la prior to sunrise. The European model (ecmwf) is less
ambitious with the rain coverage...confined mainly over Jackson Colorado
MS. Have opted to go closer to GFS idea of impulse driven
convection developed in high Theta-E air with plenty of outgoing
longwave radiation to work with late evening and overnight Sunday
night.

Long term...
the center of the high is expected to become oriented along the
eastern Seaboard and extending into the Gulf states for a period
of deep easterly flow Tuesday...possibly tainted by some fringe
moisture tapped from invest 96l or eventual tropical system east
of the U.S. Coast. Otherwise...typical temperatures and rain
chances expected Tuesday through Friday. 24/rr

Aviation...
expect VFR conditions to continue through the forecast period. There
has been some light patchy fog this morning in a few spots but
widespread fog is not expected. Convective chances rather
small...have elected not to mention thunderstorms in the vicinity in this issuance since the
coverage yesterday was so limited. 13/mh

Marine...
high pressure remains in place over the coastal waters. This high
will remain in place through the weekend. Seabreeze/landbreeze cycle
will dominate. Expect offshore winds in the morning hours and
onshore winds developing during the afternoon hours. Winds and seas
should remain fairly benign. Winds will generally be 10 knots or
less and seas will generally be 2 feet or less. Winds will take on a
more persistent easterly flow early next week as the surface high
becomes centered north of the region. East winds of 10 to 20 knots
and seas of 3 to 5 feet can be expected late Monday night through
the middle of next week. 13/mh

&&

Preliminary point temps/pops...
mcb 96 73 98 74 / 20 20 10 20
btr 96 75 99 77 / 20 20 10 10
asd 95 75 97 77 / 20 20 20 20
msy 95 79 96 80 / 20 20 20 20
gpt 95 77 97 78 / 20 20 20 20
pql 96 74 98 75 / 20 20 20 20

&&

Lix watches/warnings/advisories...
la...heat advisory until midnight Monday for the following zones:
lower Jefferson...lower Lafourche...lower
Plaquemines...lower St. Bernard...lower
Terrebonne...Orleans...St. Charles...St. John The
Baptist...upper Jefferson...upper Lafourche...upper
Plaquemines...upper St. Bernard...and upper Terrebonne.

Heat advisory from 10 am Sunday to midnight Monday for the
following zones: Ascension...Assumption...East Baton
Rouge...East Feliciana...Iberville...Livingston...northern
Tangipahoa...Pointe Coupee...southern Tangipahoa...St.
Helena...St. James...St. Tammany...Washington...West Baton
Rouge...and West Feliciana.

GM...none.
MS...heat advisory from 10 am Sunday to midnight Monday for the
following zones: Amite...Pearl
River...Pike...Walthall...and Wilkinson.

Heat advisory until midnight Monday for the following zones:
Hancock...Harrison...and Jackson.

GM...none.
&&

$$

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