Post-Tropical Ida (Cat 4 hurricane @ Landfall @12:55pm EDT, 40 mph, 998 mb, 28 mph NE) - possible area flood impact, tornadoes, and severe weather

[Hurricane Agnes]

NWS MARFC following the latest models bullseying Central PA with heavier rain from Ida remnants -

I know that part of the state has had excessive rain give how many of the convective lines that have made it this far east, but also how many fizzled before getting here where they were dumped on.  Haven't looked at their stats but it definitely has to be above normal.

 

[The Iceman]

33 minutes ago, Hurricane Agnes said:

NWS MARFC following the latest models bullseying Central PA with heavier rain from Ida remnants -

I know that part of the state has had excessive rain give how many of the convective lines that have made it this far east, but also how many fizzled before getting here where they were dumped on.  Haven't looked at their stats but it definitely has to be above normal.

 

Much like our area, they are also running 150% - 200% above normal precip this month so far. 

[The Iceman]

So far with the 12z globals we have the GFS with the heaviest axis of rain N and W of 95, the CMC with the heaviest axis South and West of 95, and the UKMET with the heaviest axis right along 95(which also matches the NAM). It's summer's version of model roulette. 

[Voyager]

28 minutes ago, The Iceman said:

So far with the 12z globals we have the GFS with the heaviest axis of rain N and W of 95, the CMC with the heaviest axis South and West of 95, and the UKMET with the heaviest axis right along 95(which also matches the NAM). It's summer's version of model roulette. 

And whichever one gives me the least amount will probably verify... 

[Hurricane Agnes]

NHC 2 pm EDT update (still 40 mph, weakend to 997 mb, no change in speed but now moving to the NNE) -

Quote

000
WTNT34 KNHC 301750
TCPAT4

BULLETIN
Tropical Storm Ida Intermediate Advisory Number 18A
NWS National Hurricane Center Miami FL       AL092021
100 PM CDT Mon Aug 30 2021

...IDA MOVING NORTH-NORTHEASTWARD OVER WESTERN MISSISSIPPI...
...HEAVY RAINFALL AND FLASH FLOODING THREAT SPREADING OVER MUCH OF
MISSISSIPPI, ALABAMA, AND THE WESTERN FLORIDA PANHANDLE...


SUMMARY OF 100 PM CDT...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...32.2N 90.5W
ABOUT 20 MI...30 KM WSW OF JACKSON MISSISSIPPI
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...NNE OR 15 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...997 MB...29.45 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

None

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for...
* Mouth of the Pearl River to the Alabama/Florida border

A Tropical Storm Warning is in effect for...
* Mouth of the Pearl River to the Alabama/Florida border

A Storm Surge Warning means there is a danger of life-threatening
inundation from rising water moving inland from the coastline in
the indicated locations. For a depiction of areas at risk, please
see the National Weather Service Storm Surge Watch/Warning Graphic,
available at hurricanes.gov.

A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area.

For storm information specific to your area, including possible
inland watches and warnings, please monitor products issued by your
local National Weather Service forecast office.


DISCUSSION AND OUTLOOK
----------------------
At 100 PM CDT (1800 UTC), the center of Tropical Storm Ida was
located near latitude 32.2 North, longitude 90.5 West. Ida is moving
toward the north-northeast near 9 mph (15 km/h), and this general 
motion is forecast to continue today.  A faster northeastward motion 
is expected to begin by tonight and continue through Tuesday night. 
On the forecast track, the center of Ida will move farther inland 
over western and central Mississippi this afternoon. Ida is then 
forecast to move over northeastern Mississippi tonight, and move 
across the Tennessee Valley on Tuesday and near the central 
Appalachians on Wednesday.

Maximum sustained winds are near 40 mph (65 km/h) with higher
gusts. Weakening is forecast during the next day or so, and Ida is 
expected to become a tropical depression later this afternoon.

Tropical-storm-force winds extend outward up to 195 miles (315 km)
mainly to southeast of the center over water.

The estimated minimum central pressure from surface observations is 
997 mb (29.45 inches).


HAZARDS AFFECTING LAND
----------------------
Key messages for Ida can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT4, WMO header WTNT44 KNHC,
and on the web at hurricanes.gov/graphics_at4.shtml?key_messages.

STORM SURGE:  The combination of a dangerous storm surge and the
tide will cause normally dry areas near the coast to be flooded by
rising waters moving inland from the shoreline.  The water could
reach the following heights above ground somewhere in the indicated
areas if the peak surge occurs at the time of high tide...

Mouth of the Pearl River to AL/FL border including Mobile
Bay...2-4 ft
Morgan City, LA to the Mouth of the Pearl River including Lake
Borgne...1-3 ft
Lake Maurepas and Lake Pontchartrain...1-3 ft
AL/FL border to Okaloosa/Walton County Line including Pensacola
Bay...1-3 ft

Surge-related flooding depends on the relative timing of the surge
and the tidal cycle, and can vary greatly over short distances.
For information specific to your area, please see products issued
by your local National Weather Service forecast office.

WIND: Tropical storm conditions will continue over portions of
southern Mississippi and southern Alabama through this afternoon.

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 are 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 this morning 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
4 to 8 inches resulting in storm total accumulations of 6 to 12
inches with isolated maximum amounts of 15 inches, today through
Tuesday morning.

Central Mississippi into far western Alabama: 4 to 8 inches with
isolated maximum amounts of 12 inches, today through tonight.

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

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.

TORNADOES:  A few tornadoes are possible through tonight, mainly
across southeast Mississippi, southern 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.

SURF:  Swells will continue to affect portions of the northern Gulf
coast through today.  These swells are likely to cause life-
threatening surf and rip current conditions. Please consult
products from your local weather office.


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

$$
Forecaster Brown

 

[Hurricane Agnes]

NHC 5 pm update (Ida now downgraded to a tropical depression, 35 mph, 999 mb, movement unchanged 9 mph NNE) -

Quote

000
WTNT34 KNHC 302037
TCPAT4

BULLETIN
Tropical Depression Ida Advisory Number  19
NWS National Hurricane Center Miami FL       AL092021
400 PM CDT Mon Aug 30 2021

...IDA BECOMES A TROPICAL DEPRESSION OVER MISSISSIPPI...
...HEAVY RAINFALL AND FLASH FLOODING THREAT CONTINUES TO SPREAD 
INLAND...


SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...32.6N 90.3W
ABOUT 20 MI...35 KM NNW OF JACKSON MISSISSIPPI
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...NNE OR 20 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...999 MB...29.50 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

All Tropical Storm and Storm Surge Warnings have been discontinued.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

There are no coastal watches and warnings in effect.


DISCUSSION AND OUTLOOK
----------------------
At 400 PM CDT (2100 UTC), the center of Tropical Depression Ida was
located near latitude 32.6 North, longitude 90.3 West. The
depression is moving toward the north-northeast near 9 mph (15 
km/h).  A faster northeastward motion is expected tonight through 
Wednesday.  On the forecast track, the center of Ida will move 
farther inland over central and northeastern Mississippi tonight. 
Ida is then forecast to move across the Tennessee Valley on 
Tuesday and near the central Appalachians on Wednesday.

Maximum sustained winds have decreased to near 35 mph (55 km/h) 
with higher gusts. Additional weakening is forecast during the 
next day or so. 

The minimum central pressure estimated from surface observations is 
999 mb (29.50 inches).


HAZARDS AFFECTING LAND
----------------------
Key messages for Ida can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT4, WMO header WTNT44 KNHC,
and on the web at hurricanes.gov/graphics_at4.shtml?key_messages.

STORM SURGE:  Water levels along the northern Gulf coast should
continue to subside through this evening.

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 this evening 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. 

Central Mississippi into far western Alabama: 4 to 8 inches with 
isolated maximum amounts of 12 inches, today through tonight. 

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.

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. 

SURF:  Swells will continue to affect portions of the northern Gulf
coast through this evening.  These swells are likely to cause life-
threatening surf and rip current conditions. Please consult
products from your local weather office.


NEXT ADVISORY
-------------
This is the last public advisory issued by the National Hurricane 
Center on Ida.  Future information on Ida can be found in Public 
Advisories issued by the Weather Prediction Center beginning at 10 
PM CDT, under AWIPS header TCPAT4, WMO header WTNT34 KWNH, and on 
the web at http://www.wpc.ncep.noaa.gov. 

$$
Forecaster Brown

 

[The Iceman]

18z nam and GFS(along with the 12z euro) are very concerning in regard to river flooding. 4-6"+ in the headwaters of the Delaware and Schuylkill combined with 2-4" further south would be bad news for much of the area.

[Hurricane Agnes]

WPC 11 pm update (holding steady at 35 mph, pressure deepend a bit to 998, moving 10 mph to NE) -

Quote

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

Entire Mt. Holly CWA in WPC Day 2 "moderate risk" for excessive precipitation -

 

[Hurricane Agnes]

NWS MARFC (as of yesterday evening) calling for near to minor river flooding for locations within the CWA -

Mt. Holly event summary (posted last night) -

[Hurricane Agnes]

SPC has parts of the southern 1/3rd of the CWA in the "marginal" and "slight risk" for severe in SWD1 & SWD2 -

 

 

[Hurricane Agnes]

The 5 am WPC update (posted right after my last update - down to 30 mph, same heading but sped up to 12 mph) -

Quote

000
WTNT34 KWNH 310849
TCPAT4

BULLETIN
Tropical Depression Ida Advisory Number  21
NWS Weather Prediction Center College Park MD   AL092021
400 AM CDT Tue Aug 31 2021

...TROPICAL DEPRESSION IDA WAS OVER NORTHERN MISSISSIPPI..
...CONSIDERABLE HEAVY RAIN AND FLOOD THREAT WILL CONTINUE TO SPREAD 
FROM THE TENNESSEE AND OHIO VALLEYS INTO THE CENTRAL AND SOUTHERN 
APPALACHIANS AND MID ATLANTIC THROUGH WEDNESDAY...


SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...34.1N 88.9W
ABOUT 145 MI...235 KM NNE OF JACKSON MISSISSIPPI
ABOUT 185 MI...300 KM SW OF NASHVILLE TENNESSEE
MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H
PRESENT MOVEMENT...NE OR 55 DEGREES AT 12 MPH...19 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 Mid-Atlantic and southern New England.


DISCUSSION AND OUTLOOK
----------------------
At 400 AM CDT (0900 UTC), the center of Tropical Depression Ida was
located near latitude 34.1 North, longitude 88.9 West. The
depression is moving toward the northeast near 12 mph (19 km/h), and
Ida is expected to continue gradually accelerating to the northeast 
over the next couple days.

Maximum sustained winds are near 30 mph (45 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: Tropical Depression Ida will track across the Middle 
Tennessee Valley, Lower Ohio Valley, and northern Mid-Atlantic 
through Thursday, producing the following rainfall totals:

Portions of the Southeast, including the western Florida panhandle, 
eastern and northern Alabama, and northern Georgia: An additional 1 
to 3 inches through Wednesday morning. 

Middle Tennessee Valley, Ohio Valley, Central and Southern 
Appalachians into the Mid-Atlantic: 3 to 6 inches with isolated 
higher amounts through Thursday morning. 

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

Considerable flash flooding is possible from the Middle Tennessee 
Valley, Ohio Valley, Central and Southern Appalachians, into 
the Mid-Atlantic and southern New England, and is most likely from 
northern West Virginia and western Maryland into southern 
Pennsylvania. Widespread minor to isolated major riverine flooding 
is occurring or forecast from the Lower Mississippi Valley into far 
western Alabama, Allegheny Mountains, and Mid-Atlantic. 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: The threat for a few tornadoes will be centered today 
across eastern Alabama, western Georgia, and the Florida Panhandle. 
On Wednesday, the threat will shift into portions of the Mid 
Atlantic.


NEXT ADVISORY
-------------
Next complete advisory at 1000 AM CDT.

$$
Forecaster Lamers

FORECAST POSITIONS AND MAX WINDS

INIT  31/0900Z 34.1N  88.9W   25 KT  30 MPH...INLAND
 12H  31/1800Z 35.0N  87.5W   20 KT  25 MPH...INLAND
 24H  01/0600Z 36.3N  84.8W   20 KT  25 MPH...INLAND
 36H  01/1800Z 37.7N  81.3W   20 KT  25 MPH...INLAND
 48H  02/0600Z 38.8N  77.6W   25 KT  30 MPH...POST-TROP/INLAND
 60H  02/1800Z 39.5N  74.6W   30 KT  35 MPH...POST-TROP/EXTRATROP
 72H  03/0600Z 40.4N  70.4W   35 KT  40 MPH...POST-TROP/EXTRATROP

Still a swirling mass of precipitation and starting to send some cloud plumes up over PA.

[Hurricane Agnes]

Got a text about the Schuylkill possibly hitting minor flood stage at the mouth  and moderate at Norristown (that I saw earlier).  Mt. Holly also posted this -

I know it won't take much to send the Wissahickon out of its banks (and that feeds the Schuylkill from little creeklets in the watershed where I am).

[RedSky]

HREF pulls a Floyd 2.0 for the doom and destruction crowd

 

[Hurricane Agnes]

WPC update (deepened a bit to 996, sped up to 15 mph so getting caught in the flow, but steady motion to the NE) -

Quote

000
WTNT34 KWNH 311513 CCA
TCPAT4

BULLETIN
Tropical Depression Ida Advisory Number  22...Corrected
NWS Weather Prediction Center College Park MD   AL092021
1000 AM CDT Tue Aug 31 2021

Corrected for current system status (TD)

...TROPICAL DEPRESSION IDA IS MOVING ACROSS THE TENNESSEE VALLEY...
...CONSIDERABLE HEAVY RAIN AND FLOOD THREAT WILL CONTINUE TO SPREAD
FROM THE TENNESSEE AND OHIO VALLEYS INTO THE CENTRAL AND SOUTHERN
APPALACHIANS AND MID ATLANTIC THROUGH WEDNESDAY...


SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...35.0N 87.8W
ABOUT 60 MI...95 KM WNW OF HUNTSVILLE ALABAMA
ABOUT 100 MI...160 KM SW OF NASHVILLE TENNESSEE
MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H
PRESENT MOVEMENT...NE OR 50 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...996 MB...29.42 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 Mid-Atlantic and southern New England.


DISCUSSION AND OUTLOOK
----------------------
At 1000 AM CDT (1500 UTC), the center of Tropical Depression Ida was
located near latitude 35.0 North, longitude 87.8 West. The
depression is moving toward the northeast near 15 mph (24 km/h) and
this motion is expected to gradually accelerate over the next couple 
of days.

Maximum sustained winds are near 30 mph (45 km/h) with higher gusts.
Little change in strength is forecast during the next 48 hours. 

The estimated minimum central pressure is 996 mb (29.42 inches).


HAZARDS AFFECTING LAND
----------------------
RAINFALL: Tropical Depression Ida will produce the following
rainfall totals:

Portions of the Southeast, including the western Florida panhandle,
eastern and northern Alabama, and northern Georgia: An additional 1
to 3 inches through Wednesday morning.

Middle Tennessee Valley, Ohio Valley, Central and Southern
Appalachians into the Mid-Atlantic: 3 to 6 inches with isolated
higher amounts through Thursday morning.

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

Considerable flash flooding is possible from the Middle Tennessee
Valley, Ohio Valley, Central and Southern Appalachians, into the
Mid-Atlantic and southern New England, with additional widespread
moderate and isolated major river flooding impacts forecast from
northern West Virginia and western Maryland into southern
Pennsylvania and New Jersey.

Widespread minor to isolated major river 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: The threat for a couple of tornadoes will be centered
this evening across eastern Alabama, western Georgia, and the
Florida Panhandle. On Wednesday, the threat of a few tornadoes will
shift into portions of the Mid Atlantic.


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

$$
Forecaster Churchill

FORECAST POSITIONS AND MAX WINDS

INIT  31/1500Z 35.0N  87.8W   25 KT  30 MPH...INLAND
 12H  01/0000Z 36.0N  85.8W   25 KT  30 MPH...INLAND
 24H  01/1200Z 37.4N  82.7W   20 KT  25 MPH...INLAND
 36H  02/0000Z 38.6N  79.0W   20 KT  25 MPH...INLAND
 48H  02/1200Z 39.7N  75.6W   25 KT  30 MPH...POST-TROP/INLAND
 60H  03/0000Z 40.5N  72.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 72H  03/1200Z 41.3N  68.7W   35 KT  40 MPH...POST-TROP/EXTRATROP
 96H  04/1200Z...POST-TROP/EXTRATROP

 

[Hurricane Agnes]

1 minute ago, RedSky said:

HREF pulls a Floyd 2.0 for the doom and destruction crowd

 

LOL  I don't think I'll ever forget Floyd.  We were let out of work early and it took me 3 hours navigating around the flooded city streets to go the 12 miles to get home.

[RedSky]

2 minutes ago, Hurricane Agnes said:

LOL  I don't think I'll ever forget Floyd.  We were let out of work early and it took me 3 hours navigating around the flooded city streets to go the 12 miles to get home.

I watched a neanderthal pinhead walk across park creek with water at mid chest level. I still can't believe he didn't get swept away 

[Hurricane Agnes]

Mt. Holly retweeted the SWD2 from SPC that just put some of Philly metro into the "enhanced risk" category for severe (which tends to be rare for them to do for our area) -

 

[dssbss]

What are we thinking time window wise for the heaviest/flash flooding risk? Specifically near Reading? Asking as I work for a school district.


.

[Kevin Reilly]

10 minutes ago, dssbss said:

What are we thinking time window wise for the heaviest/flash flooding risk? Specifically near Reading? Asking as I work for a school district.


.

Brittany Ship says the flooding and severe thunderstorms start tonight???????  Does she even look at the models??????  I am very confused??

[CoolHandMike]

10 minutes ago, dssbss said:

What are we thinking time window wise for the heaviest/flash flooding risk? Specifically near Reading? Asking as I work for a school district.


.

WU says the rates really pick up in the afternoon but as much as an inch might have already fallen by then. Tomorrow's evening rush is going to be a mess.

[Hurricane Agnes]

WPC 5 pm update (winds have dropped, pressure has risen, and movement has increased to 17 mph as it gets drawn to the NE as a huge rainstorm) -

Quote

054 
WTNT34 KWNH 312059
TCPAT4

BULLETIN
Tropical Depression Ida Advisory Number  23
NWS Weather Prediction Center College Park MD   AL092021
400 PM CDT Tue Aug 31 2021

...TROPICAL DEPRESSION IDA IS MOVING ACROSS THE TENNESSEE VALLEY...
...WIDESPREAD HEAVY RAIN AND AREAS OF POTENTIALLY LIFE THREATENING 
FLASH FLOODING ARE POSSIBLE BEGINNING WEDNESDAY ACROSS PORTIONS OF 
THE MID ATLANTIC AND SOUTHERN NEW ENGLAND...


SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...35.5N 86.2W
ABOUT 65 MI...105 KM NNE OF HUNTSVILLE ALABAMA
ABOUT 125 MI...200 KM W OF KNOXVILLE TENNESSEE
MAXIMUM SUSTAINED WINDS...25 MPH...35 KM/H
PRESENT MOVEMENT...NE OR 55 DEGREES AT 17 MPH...28 KM/H
MINIMUM CENTRAL PRESSURE...999 MB...29.50 INCHES


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


DISCUSSION AND OUTLOOK
----------------------
At 400 PM CDT (2100 UTC), the center of Tropical Depression Ida was
located near latitude 35.5 North, longitude 86.2 West. The
depression is moving toward the northeast near 17 mph (28 km/h) and
this motion is expected to gradually accelerate through Wednesday. 

Maximum sustained winds are near 25 mph (35 km/h) with higher gusts.
Some strengthening is forecast during the next 48 hours as Ida 
becomes extratropical and moves offshore by early Thursday.

The estimated minimum central pressure is 999 mb (29.50 inches).


HAZARDS AFFECTING LAND
----------------------
RAINFALL: Tropical Depression Ida will produce the following
rainfall totals:

Portions of the Southeast, including the western Florida panhandle,
eastern and northern Alabama, and northern Georgia: An additional 1
to 3 inches through Wednesday morning.

Middle Tennessee Valley, Ohio Valley, Central and Southern
Appalachians: 3 to 6 inches with isolated higher amounts through
Wednesday morning.

Mid Atlantic to Southern New England: 3 to 8 inches with isolated
higher amounts, Wednesday into Thursday.

Considerable flash flooding is possible from the Middle Tennessee
Valley, Ohio Valley, Central and Southern Appalachians.

Significant and life-threatening flash flooding is possible from the
Mid-Atlantic into southern New England, especially across highly
urbanized metropolitan areas and areas of steep terrain. Widespread
moderate and major river flooding impacts are forecast from northern
West Virginia and western Maryland into southern Pennsylvania and
New Jersey, particularly in the Monongahela, Potomac, Susquehanna,
Delaware, and lower Hudson river basins.

Widespread minor to isolated major river 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: The threat for an isolated tornado will continue this
evening across portions of the Southeast, shifting towards portions
of the Mid Atlantic overnight. On Wednesday, several tornadoes are
probable across portions of the Mid Atlantic, mainly during the
afternoon and evening hours.


NEXT ADVISORY
-------------
Next complete advisory at 1000 PM CDT.

$$
Forecaster Churchill

FORECAST POSITIONS AND MAX WINDS

INIT  31/2100Z 35.5N  86.2W   20 KT  25 MPH...INLAND
 12H  01/0600Z 37.0N  83.5W   20 KT  25 MPH...INLAND
 24H  01/1800Z 39.0N  79.0W   25 KT  30 MPH...INLAND
 36H  02/0600Z 40.4N  73.6W   35 KT  40 MPH...POST-TROP/EXTRATROP
 48H  02/1800Z 43.8N  67.4W   35 KT  40 MPH...POST-TROP/EXTRATROP

I did see some mention about the conditions possibly causing it to strengthen a bit as it moves closer to the area...  I also saw that TD-12 has formed and if it gets named, it will be "Larry".  It's way way over just south of Cape Verde.

[RedSky]

2 hours ago, Kevin Reilly said:

Brittany Ship says the flooding and severe thunderstorms start tonight???????  Does she even look at the models??????  I am very confused??

Storms are organizing in south central PA already, I could see heavy showers and storms in the overnight. 

 

[Hurricane Agnes]

Now this is cool - the Schuylkill has a new gauge at 30th St (retweeted by Mt. Holly)!

I usually like looking at USGS's page, which for this new gauge is here - https://waterdata.usgs.gov/nwis/uv?site_no=01474501

Kinda cool to see the gauge readings and it was looking like it was actually tidal (the one on the Schuylkill across from the Waterworks doesn't do that) and wasn't sure if that was what I was actually seeing until I looked at the Delaware River one (the deeper one at Penn's Landing) and saw a matching pattern, and I know the Delaware is tidal. 

[Eskimo Joe]

1 hour ago, Hurricane Agnes said:

Now this is cool - the Schuylkill has a new gauge at 30th St (retweeted by Mt. Holly)!

I usually like looking at USGS's page, which for this new gauge is here - https://waterdata.usgs.gov/nwis/uv?site_no=01474501

Kinda cool to see the gauge readings and it was looking like it was actually tidal (the one on the Schuylkill across from the Waterworks doesn't do that) and wasn't sure if that was what I was actually seeing until I looked at the Delaware River one (the deeper one at Penn's Landing) and saw a matching pattern, and I know the Delaware is tidal. 

The Schuylkill River is tidal from the Art Museum dam and below. Grew up in Roxborough and know the river and Wissahickon Creek well.

[Hurricane Agnes]

7 hours ago, Eskimo Joe said:

The Schuylkill River is tidal from the Art Museum dam and below. Grew up in Roxborough and know the river and Wissahickon Creek well.

That's just fascinating!!!!

I'm glad a new gauge was put there.  Since they have developing all around that area from 25th St. down to the 30th St. corridor (e.g., "Schuylkill Banks" and the pedestrian walkways, etc. running along the river), I expect that monitoring flooding right around there is critical.

[Hurricane Agnes]

WPC 5 am update (strengthened a bit to 30 mph but now a more weak low at 1000 mb, and has now been officially caught in the flow and rolling at 24 mph to the NE) -

Quote

000
WTNT34 KWNH 010839
TCPAT4

BULLETIN
Tropical Depression Ida Advisory Number  25
NWS Weather Prediction Center College Park MD   AL092021
500 AM EDT Wed Sep 01 2021

...TROPICAL DEPRESSION IDA IS MOVING INTO THE CENTRAL
APPALACHIANS AND SHOULD BECOME POST-TROPICAL TODAY...
...WIDESPREAD HEAVY RAIN AND AREAS OF LIFE THREATENING FLASH
FLOODING ARE LIKELY TODAY AND TONIGHT NEAR THE TRACK OF IDA...
...ENHANCED RISK FOR SEVERAL TORNADOES ACROSS PARTS OF THE
MID-ATLANTIC ON WEDNESDAY...


SUMMARY OF 500 AM EDT...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...37.3N 82.5W
ABOUT 135 MI...220 KM W OF ROANOKE VIRGINIA
ABOUT 135 MI...215 KM NE OF KNOXVILLE TENNESSEE
MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H
PRESENT MOVEMENT...NE OR 55 DEGREES AT 24 MPH...39 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES


WATCHES AND WARNINGS
--------------------
Flood and Flash Flood Watches are in effect for portions of the
central Appalachians, Mid-Atlantic, and into southern New York and
southern New England.

A Tornado Watch is in effect until 8 AM EDT Wednesday across
the District of Columbia, central and northern Maryland, and
northeastern Virginia. For the latest severe weather outlooks and
status of watches, including Tornado Watches, please refer to the
Storm Prediction Center.


DISCUSSION AND OUTLOOK
----------------------
At 500 AM EDT (0900 UTC), the center of Tropical Depression Ida was
located near latitude 37.3 North, longitude 82.5 West. The
depression is moving toward the northeast near 24 mph (39 km/h) and
this motion is expected to continue over the next couple days.

Maximum sustained winds are near 30 mph (45 km/h) with higher gusts.
Some strengthening is forecast later today and tonight as Ida 
becomes extratropical.

The estimated minimum central pressure is 1000 mb (29.53 inches).


HAZARDS AFFECTING LAND
----------------------
RAINFALL: Tropical Depression Ida will produce the following
rainfall totals:

Mid Atlantic to Southern New England: 3 to 8 inches with isolated
higher amounts through Thursday.

Significant and life-threatening flash flooding is likely from the
Mid-Atlantic into southern New England, especially across highly
urbanized metropolitan areas and areas of steep terrain. Widespread
moderate and major river flooding impacts are forecast from northern
West Virginia and western Maryland into southern Pennsylvania and
New Jersey, particularly in the Monongahela, Potomac, Susquehanna,
Delaware, and lower Hudson river basins.

Widespread minor to isolated major river flooding is occurring or
forecast from the Lower Mississippi Valley into far western Alabama
and northeast Georgia. 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: Several tornadoes are probable across portions of the
Mid Atlantic today, mainly during the afternoon and evening hours.


NEXT ADVISORY
-------------
Next complete advisory at 1100 AM EDT.

$$
Forecaster Lamers

FORECAST POSITIONS AND MAX WINDS

INIT  01/0900Z 37.3N  82.5W   25 KT  30 MPH...INLAND
 12H  01/1800Z 38.9N  79.1W   30 KT  35 MPH...POST-TROP/INLAND
 24H  02/0600Z 41.2N  73.7W   35 KT  40 MPH...POST-TROP/INLAND
 36H  02/1800Z 43.8N  68.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
 48H  03/0600Z 46.1N  65.1W   35 KT  40 MPH...POST-TROP/EXTRATROP

 

[LVLion77]

Does anyone see the eastern PA several inch rainfall forecasts materializing today? There is a decent batch of moisture but not looking that dire at this point.

[hazwoper]

3 minutes ago, LVLion77 said:

Does anyone see the eastern PA several inch rainfall forecasts materializing today? There is a decent batch of moisture but not looking that dire at this point.

Ahhh….yeah!

[Hurricane Agnes]

2 minutes ago, LVLion77 said:

Does anyone see the eastern PA several inch rainfall forecasts materializing today? There is a decent batch of moisture but not looking that dire at this point.

I've been getting some light rain since before 4:30 am and am already up to 0.49" here in NW Philly.  It's just getting started

[Hurricane Agnes]

Just tweeted from Mt. Holly -

I was hopping around literally a pile of radar sites and they are all solid with returns (KRLX, KPBZ, KLWX, KCCX, KDOX, and of course KDIX).