Monday, August 30, 2021

Ida Now A Tropical Depression Drifts Through the Deep South







































000
WTNT34 KWNH 310248
TCPAT4

BULLETIN
Tropical Depression Ida Advisory Number  20
NWS Weather Prediction Center College Park MD   AL092021
1000 PM CDT Mon Aug 30 2021

...TROPICAL DEPRESSION IDA WAS OVER CENTRAL MISSISSIPPI..
...HEAVY RAIN AND FLOOD THREAT WILL CONTINUE TO SPREAD ACROSS
PARTS OF THE TENNESSEE AND OHIO VALLEY OVERNIGHT INTO
TUESDAY...

SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...33.3N 89.5W
ABOUT 80 MI...130 KM NNE OF JACKSON MISSISSIPPI
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...NE OR 50 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...998 MB...29.47 INCHES


WATCHES AND WARNINGS
--------------------
Flood and Flash Flood Watches extend from the Gulf Coast
Region across the Tennessee and Ohio Valleys, central and southern
Appalachians, into the northern Mid-Atlantic and southern New
England.

DISCUSSION AND OUTLOOK
----------------------
At 1000 PM CDT (0300 UTC), the center of Tropical Depression Ida was
located near latitude 33.3 North, longitude 89.5 West. The
depression is moving toward the northeast near 10 mph (17 km/h) and
this motion is expected to continue overnight.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Little change in strength is forecast during the next 48 hours. 

The estimated minimum central pressure is 998 mb (29.47 inches).

HAZARDS AFFECTING LAND
----------------------
RAINFALL: Through Tuesday morning across portions of southeast
Louisiana into far southern Mississippi, Ida will produce additional
rainfall totals of 2 to 4 inches with localized higher amounts
possible. Storm total rainfall accumulations of 10 to 18 inches with
isolated maximum amounts of 24 inches is expected. Heavy rain
combined with storm surge has resulted in catastrophic impacts along
the southeast coast of Louisiana with considerable flash flooding
and riverine flooding continuing farther inland.

Ida will continue to turn northeast tonight and is forecast to
track across the Middle Tennessee Valley, Ohio Valley and
Mid-Atlantic through Wednesday, producing the following rainfall
totals:

Coastal Alabama to the far western Florida panhandle: An additional
3 to 6 inches resulting in storm total accumulations of 6 to 12
inches with isolated maximum amounts of 15 inches, today through
Tuesday morning.

Northern Mississippi, Middle Tennessee Valley, Ohio Valley,
Central/Southern Appalachians into the Mid-Atlantic: 3 to 6 inches
with isolated higher amounts, Tuesday into Wednesday.

Southern New England: 2 to 4 inches with isolated higher amounts,
Wednesday into Thursday.

Considerable flash flooding is possible from the Lower Mississippi
Valley through the Middle Tennessee Valley, Ohio Valley,
Central/Southern Appalachians, and into the Mid-Atlantic. Widespread
minor to isolated major riverine flooding is occurring or forecast
from the Lower Mississippi Valley into far western Alabama. Rivers
will remain elevated into next week.

For the latest rainfall reports and wind gusts associated with 
Tropical Depression Ida, see the companion storm summary at 
WBCSCCNS4 with the WMO header of ACUS44 KWBC or at the following 
link:

www.wpc.ncep.noaa.gov/discussions/nfdscc4.html

TORNADOES:  A few tornadoes are possible through tonight, mainly
across far southeast Mississippi, the southern half of Alabama, and
the western Florida Panhandle. The threat for a few tornadoes will
shift east on Tuesday and become centered across eastern Alabama,
western Georgia, and the Florida Panhandle.

NEXT ADVISORY
-------------
Next complete advisory at 400 AM CDT.

$$
Forecaster Bann

FORECAST POSITIONS AND MAX WINDS

INIT  31/0300Z 33.3N  89.5W   30 KT  35 MPH...INLAND
 12H  31/1200Z 34.2N  88.4W   25 KT  30 MPH...INLAND
 24H  01/0000Z 35.7N  85.7W   25 KT  30 MPH...INLAND
 36H  01/1200Z 37.0N  82.8W   25 KT  30 MPH...INLAND
 48H  02/0000Z 38.0N  79.7W   25 KT  30 MPH...POST-TROP/INLAND
 60H  02/1200Z 39.0N  75.9W   30 KT  35 MPH...POST-TROP/EXTRATROP
 72H  03/0000Z 39.6N  72.2W   30 KT  35 MPH...POST-TROP/EXTRATROP

000
FXUS61 KCAR 310158
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
958 PM EDT Mon Aug 30 2021

.SYNOPSIS...
A weak cold front will cross the area this afternoon
and evening. High pressure will build toward the region Tuesday
into Wednesday. The remnant low pressure of Ida is currently
expected move well south of the region Thursday into Friday....

......SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
Tuesday Night...Looking for a mostly clear, quiet night. Still a
bit of a pressure gradient over the area along with some low-
level cold advection, so some areas may not decouple despite
mostly clear skies. Think that central/northern valleys have the
best shot at decoupling, and went with lows as cool as the mid
to upper 40s for some northern valleys. Could be some patchy
valley fog in valleys that decouple.

Wednesday...Dry, mild westerly flow over the area with partly cloudy
skies. Highs ranging from the upper 60s to upper 70s, warmest
Downeast.

Wednesday Night...One more quiet night Wednesday night. Expect
increasing clouds Downeast ahead of the next system (remnants of
Ida), though Northern Maine should remain partly cloudy.
Temperatures ranging from the upper 30s to mid 40s in the north
to mid 50s Downeast.

Thursday...Forecast confidence remains low on the track of Ida`s
remnants. Models not in any better agreement than they were
yesterday. The question is how far north the rain makes it. If
it were to make it north into our area, rain would be developing
during the day. Some models keep Ida`s rain well offshore, while
others bring the rain well inland. And there`s everything in
between for model/ensemble solutions. The more northern
solution would involve a stronger surface low/Nor`easter in the
Northern Gulf of Maine, while the weaker/southern solution would
involve more of an open/flat wave. EC ensembles tend to be
wetter/further north than GFS ensembles, but each ensemble
system has large variability. This is all a concern because the
northern envelope of solutions could bring impactful rain
especially to Downeast (potential for over 2" in less than 12
hours) as well as decent wind. But there is also the very real
possibility of nothing. For now, stayed the course with PoPs,
with likely PoPs only south/east of Bangor.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Thursday Night through Saturday...Tentatively expect Ida`s
remnants/potential Nor`easter to move east with drying Thursday
night and Friday, that is, if Ida`s moisture even gets this far
north in the first place Thursday/Thursday evening. What`s
tricky is that some models, specifically the ECMWF and some of
its ensembles, stall out the Nor`easter over the Canadian
Maritimes potentially keeping rain into Saturday. But most
models kick it out enough to where Friday/Saturday would be dry
expect for perhaps a few afternoon showers.

Sunday/Monday...West/southwest flow over the area with seasonal
temperatures and a small chance of an afternoon storm.....

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