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

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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.....