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New Orleans Local Weather thread - ROLLTIDE - 02-21-2008 09:43 AM

Area forecast discussion
National Weather Service New Orleans la
357 am CST Thursday Feb 21 2008


Short term...
warm frontal boundary and strong moisture convergence near shore
this morning will make for a long day. Moderate jet dynamics will
increase as the SW upper low approaches causing the linear
subtropical jet to dig southward. This will help a split flow
develop aloft today making conditions ripe for severe thunderstorm
development. Main concern through the day will be tornadic
activity but this will also be accompanied by strong damaging
winds...large hail...frequent to continuous lightning and very
heavy rainfall. These variables were updated in the severe weather potential statement already
this morning and will simply be sent out on the products normal
issuance time wtih the addition of Tornado Watch #69.


The cold front will be slow to move through as two upper troughs
will be slow to reach the area to lend more forcing to finally
push the front through by Saturday morning. The first upper trough
can be seen moving south out of Montana into Colorado while the
other is moving east through The Four Corners region. The northern
most upper trough will be the one to lend the forcing that will
finally kick the front away. But it will have to wait on The Four
Corners trough to move through first. This all just sets up a long
duration severe weather potential through most of Friday.


The other problem that may become evident is rainfall. Isolated
areas of very heavy rainfall are expected today through a portion
of Friday. Grounds are wet already from recent rains and wont take
much to cause some minor flooding of roadways and low lying areas.
With the slow movement of the cold front...a few areas may see
training of thunderstorm activity through Friday. 2 to 4 inches
over much of the area can be expected with some isolated higher
amounts through tonight. Friday will add to the rainfall tally but
will have to reasses numbers later today. If heavier amounts of
rainfall is recieved...a Flood Watch will be contemplated.


Long term...
a dry system is expected to move through Sunday but another potent
system will be moving into the area by middle to late next week.


New Orleans Local Weather thread - ROLLTIDE - 02-22-2008 09:46 AM

fxus64 klix 221020
afdlix


Area forecast discussion
National Weather Service New Orleans la
420 am CST Friday Feb 22 2008


Short term...
tornados watch #72 will be expiring at 4am and no other convective
watches are expected to go up as the southern end of the line of
ts is decaying. An isolated severe may be the only possibility as the
line enters Walthal County but all other locations should only see
a weak line of sh/ts move through. Another line of sh/ts is
beginning to develop well ahead of the primary line which will
continue to develop and steal moisture from the south end of the
primary line. Rainfall should become less of a concern with
respect to flooding since the line will become narrower.
Eventhough the line is moving very slowly...the width of the line
will keep areas from receiving enough rain to cause problems.


Sunday morning will see another surface low move through. The upper
level support for the surface low will be a strong short wave digging
southward. This will make the cloud shield and rain associated
with this system move in from the northwest. This upper level disturbance
is just getting started off the coast of northern cal this
morning as a very fast moving jet crashes into a strong stacked
high over the middle portion of the country. Eventually this will
cause the West Coast jet to buckle far north causing an inflection
downstream simply replacing the deep East Coast trough that has
been over the country for the past week.


Long term...
next system to move into the area by middle next week.


New Orleans Local Weather thread - ROLLTIDE - 02-25-2008 09:20 AM

Short term...


Areas of dense fog will linger through the morning rush across the
Mississippi coast and Northshore of Lake Pontchartrain...as light
boundary layer winds...a strong inversion...and dewpoint
temperatures near the water temperatures over the lake and
Mississippi Sound remain in place. Over coastal southeast
Louisiana and the southshore of Lake Pontchartrain patchy dense
fog will linger through the morning rush before burning off. Will
keep the dense fog advisory out for the Mississippi coast and
Northshore to reflect these expected conditions.


Beyond the immediate term concerns...a fast moving system will
impact the region over the next 24 hours. A strong trough of low
pressure currently over the northern rockies...combined with an
Arctic surge racing southward across the Canadian prairies will
allow for the formation of a fairly deep longwave trough across
the eastern two thirds of the nation tonight into tomorrow. Strong
Lee cyclogenesis over the Central Plains is currently taking
place...with a fairly potent surface low developing over western
Kansas. This low is expected to race eastward into the Midwest
today...and then into the northeast by tomorrow. As the low sweeps
to the east...the strong surge of Arctic air will plunge southward
across the plains states and into the lower Mississippi Valley. In
advance of this surge of Arctic air...and the associated cold
front...a fairly unstable airmass should be in place. A line of
convection should form along the front and push through the
forecast area overnight into early tomorrow morning. The strongest
dynamics will be well to the north of the region...but some speed
shear in place could lead to a few stronger thunderstorms
overnight.


The front should race offshore into the central Gulf of Mexico by
tomorrow afternoon...with strong cold air and negative vorticity
advection taking hold of the region. Rapidly clearing skies and
falling temperatures are expected for Tuesday and Tuesday night in
the wake of the front. In addition...strong winds aloft will be
transported down to the surface Tuesday night due to the strong
subsidence expected by the front. By Wednesday...thicknesses
should be a full 2000 meters below what is expected for today.
Surface ridging will also be in place across the Gulf south as
deep northwest flow dominates the region aloft.


Long term...


Overall uncertainty in the forecast going beyond Wednesday remains
fairly high tonight...as the models are still showing some phase
discrepancies with the next two systems. After looking at both the
GFS and European model (ecmwf) and comparing to past runs for model
consistency...have decided to lean more toward the European model (ecmwf) for the
overall extended forecast package.


With this in mind...expect some recovery of temperatures on
Thursday...as a southerly flow redevelops across the region...due
to the surface ridge sliding to the east. Aloft...a fairly zonal
flow should be in place across the Gulf south...while a clipper
system dives from the Canadian plains into the Great Lakes. The
clipper system should drive a frontal boundary toward the region
Thursday night and stall the front over the area on Friday.
The front should stall...mainly due to a lack of dynamic forcing
as the upper level trough axis pulls to the northeast of the
region...and the airmass modifies considerably as it descends into
the mid-south. There should be just enough Omega...and some low
level instability to produce a few showers and thunderstorms on
Friday along and ahead of the frontal boundary. This boundary
should linger through Saturday and serve primarily as a focus for
a shower development. Have kept in slight chance probability of precipitation to reflect
the warm and moist airmass expected to be in place interacting
with the remnant boundary.


Going into Sunday...a very strong upper level trough should pull
through the West Coast and into The Four Corners region. Southerly
flow will increase off the Gulf across the region...which should
wash out the stalled frontal boundary. At the same time...a
developing jet streak across the plains states could lead to a
broad area of lift across the forecast area. A more moist airmass
along with this broad area of ascent could lead to a few showers
forming over the region Sunday into Sunday night. Temperatures
should be well above normal as warm Gulf air is transported into the
region. The trough should kick into Texas on Monday...as a low
develops over the arklamiss. This low and an associated cold front
should sweep through the Gulf south Monday night into Tuesday.


New Orleans Local Weather thread - ROLLTIDE - 02-29-2008 10:22 PM

Special Weather Statement[Image: SPE.gif]Statement as of 3:45 PM CST on February 29, 2008

... An upper level trough is expected to intensify over the
southeast Louisiana and southern Mississippi and bring the threat of
severe weather and very strong winds Monday through early Tuesday...

There is potential for a significant severe weather outbreak Monday
and Monday night across southeast Louisiana and southern Mississippi.
An upper level trough... approaching Oregon and Washington... is
expected to dive southeast over the central and Southern Plains late
Sunday and lower Mississippi Valley Monday through Tuesday. Wind
profiles... instability and the dynamic nature of this early Spring
storm will be conducive for the development of supercell storms with
large hail and a few tornadoes ahead of the associated cold front
Monday. Moreover... a squall line of strong to severe thunderstorms
with hail and damaging winds is expected along the cold front Monday
afternoon and evening.

Very strong winds ahead and behind the cold front will affect
southeast Louisiana... south Mississippi and adjacent coastal waters.
Strong south to southwest winds of 25 to 30 knots with gusts over
40 knots may start to impact coastal waters of southeast Louisiana
and south Mississippi Monday. South to southwest winds of 20 to 30
miles an hour with gusts up to 35 miles an hour Monday will affect
southeast Louisiana and southern Mississippi.

After the frontal passage... west to northwest winds 35 to 45 knots
with gusts up to 45 knots can be expected Tuesday. In addition... west
to northwest of 25 to 30 miles an hour... especially south of Lake
Pontchartrain... will occur late Monday night and Tuesday. As a
result... gale warnings and wind advisories will likely be issued for
part or all of southeast Louisiana... south Mississippi and adjacent
coastal waters Monday through Tuesday.

Residents and mariners of southeast Louisiana and south Mississippi
should monitor the latest statements and forecasts on this developing
weather system on Monday.


New Orleans Local Weather thread - ROLLTIDE - 03-06-2008 08:49 AM

Area forecast discussion
National Weather Service New Orleans la
429 am CST Thursday Mar 6 2008


Discussion...
GFS...NAM...ECMWF and NGM glaring differences were the position
of the surface low and the decrease in thickness values Friday off
the GFS. Moreover...GFS develops a jet maximum of 140 knots over
Mississippi and Alabama/ahead of the main trough axis and create
good divergence. In addition...GFS showed a 6 hourly quantitative precipitation forecast swath of
3 inches over southeast Louisiana coastal waters.


Will stay somewhat clear of GFS and go with European model (ecmwf) and NAM blend
with surface wind direction forecast but increase wind speeds
through Friday. The main trough over the central rockies is expected to
sharpen over the plains but remain positively tilted. Surface low
is expected develop over southeast Texas and southwest Louisiana
this afternoon...then sweeps east. Surface flow will become east
to southeast over the area. Dewpoints were around 50f over northeast
Gulf...thus increase surface moisture will occur tonight. Deep
moisture should remain over coastal waters as land deep readings
should remain below 60f. The approach of the main trough will
strengthen SW flow in the middle layers and south flow in the lower
levels. This will increase moisture and middle layer instability.
Will keep thunder in forecast after 06z Friday and hold highest
chance of rain after 06z Friday. With sharp trough passage...cold
air advection is expected Friday with strong winds over the
coastal waters through Saturday. Lowering thickness values will keep
temperatures below norms through the weekend and keep the azaleas from
blooming fully. Another southern track storm will bring a chance of
rain across the area late Wednesday into Thursday.


&&


Aviation...
VFR conditions are expected to prevail at all taf sites through the
period. There will be a chance of some MVFR visibilities due to light fog
during the early morning hours at mcb and gpt. A strengthening
southwest flow by noon will create a ceiling of 4 to 5kft at the
taf sites 18z to 00z Friday. These ceilings will likely lower to
3kft by 06z Friday with light rain and mist restricting visibility
down to 3 to 5sm at times 00z to 06z Friday.


New Orleans Local Weather thread - Southernbelle - 03-13-2008 07:06 AM

N.O.: forgotten and neglected.


New Orleans Local Weather thread - dkmac - 03-13-2008 07:19 AM

Don't know where Roll went, but here ya go Belle:

Area Forecast Discussion
000
FXUS64 KLIX 130845
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
345 AM CDT THU MAR 13 2008

.DISCUSSION...

EARLY THIS MORNING SURFACE HIGH PRESSURE WAS CENTERED OVER THE
NORTHEASTERN GULF OF MEXICO AND A LOW PRESSURE SYSTEM WAS
DEVELOPING OVER NORTHWESTERN TEXAS. AN UPPER-LEVEL TROUGH WAS
OVER THE WESTERN STATES. THE UPPER TROUGH IS EXPECTED TO PUSH
EASTWARD THROUGH THE LOWER MISSISSIPPI VALLEY THURSDAY NIGHT AS
THE LOW MOVES INTO ARKANSAS. THIS WILL BRING SHOWERS/THUNDERSTORMS
TO OUR AREA TONIGHT THROUGH EARLY FRIDAY. THIS IS A LITTLE FASTER
THAN PREVIOUS MODEL RUNS. HIGH PRESSURE WILL BUILD INTO THE LOWER
MISSISSIPPI VALLEY SATURDAY AND SUNDAY AS A DEEP UPPER TROUGH
DROPS INTO THE SOUTHWESTERN STATES. AS THIS TROUGH PROGRESSES
EASTWARD INTO THE CENTRAL PLAINS STATES...A SURFACE LOW WILL
DEVELOP AROUND OKLAHOMA AND KANSAS MONDAY NIGHT. BY TUESDAY
AFTERNOON...THE SHARP UPPER TROUGH WILL BE MOVING INTO EASTERN
TEXAS AS THE SURFACE LOW PUSHES TOWARD THE WESTERN GREAT LAKES AND
ASSOCIATED COLD FRONT PUSHES INTO LOUISIANA. THIS SYSTEM WILL HAVE
STRONG DYNAMICS AND AMPLE MOISTURE WITH IT. THEREFORE...IF THIS
GFS SOLUTION IS CORRECT...WE COULD HAVE SOME STRONG TO SEVERE
STORMS ON TUESDAY. THE ECMWF CONTINUES TO BE SLOWER WITH THIS
SYSTEM.

.AVIATION...

VFR CONDITIONS ARE EXPECTED TODAY. 5000 FOOT CEILINGS WILL BEGIN
TO AFFECT THE AREA AFTER SUNSET...WITH THE PRIMARY THREAT OF
THUNDERSTORMS GENERALLY AFTER MIDNIGHT.

.MARINE...

SMALL CRAFT CONDITIONS ARE BRIEFLY POSSIBLE BEFORE THE FRONTAL
PASSAGE FRIDAY NIGHT/SATURDAY MORNING...THEN MORE LIKELY BEHIND
THE FRONT SATURDAY NIGHT INTO SUNDAY.


New Orleans Local Weather thread - Southernbelle - 03-14-2008 08:48 AM

thank you


New Orleans Local Weather thread - Southernbelle - 03-18-2008 06:29 AM

southernbelle Wrote:N.O.: forgotten and neglected.

once again?


New Orleans Local Weather thread - Windwatcher - 03-18-2008 06:39 AM

Be aware of the possibility of falling pine trees in this wind. There are so many weak ones out there; it doesn't take much to push them down.