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]

WPC just got real -

From NWS MARFC -

 

[The Iceman]

Looking at guidance, it seems se pa should be dry for the remainder of the day. Then we get a 6 hour blast of heavy rain sometime this evening as the low approaches. The further n and w guidance definitely seems to be verifying, heaviest amounts will be LV into the Poconos.

[Hurricane Agnes]

7 minutes ago, The Iceman said:

Looking at guidance, it seems se pa should be dry for the remainder of the day. Then we get a 6 hour blast of heavy rain sometime this evening as the low approaches. The further n and w guidance definitely seems to be verifying, heaviest amounts will be LV into the Poconos.

There are some blobs of convection associated with the storm that have been cutting across VA and MD and generally going to the NE, along with the wider band that is funneling to the NW, so we might get something out of the southern blobs.

[The Iceman]

I haven't seen the 06z euro but 00z is pretty much only 1-2" for much of SE PA. GFS is trending that way as well. We'll have to see how the day unfolds. Latest HRRR is still on track for 2-4" but SE PA stays dry until around 00z tonight then 2-4" falls in a 6 hour time period. At .5" for the event so far but rain has stopped and sun is even poking through the clouds at times.

[JTA66]

5 minutes ago, The Iceman said:

I haven't seen the 06z euro but 00z is pretty much only 1-2" for much of SE PA. GFS is trending that way as well. We'll have to see how the day unfolds. Latest HRRR is still on track for 2-4" but SE PA stays dry until around 00z tonight then 2-4" falls in a 6 hour time period. At .5" for the event so far but rain has stopped and sun is even poking through the clouds at times.

Maybe the Al-tuna guy will get flooded out of his parents' basement.

Another heavy shower moved through, up to .40".

[The Iceman]

New 12z NAM is north like the euro. Only 1-1.5" for much of SE PA. 3Km NAM is even less than that. Tornado threat now looking like the more concerning issue for Philly and Burbs as opposed to flooding. N and W burbs get crushed though.

 

[LVLion77]

New 12z NAM is north like the euro. Only 1-1.5" for much of SE PA. 3Km NAM is even less than that. Severe threat now looking like the more concerning issue for Philly and Burbs as opposed to flooding. N and W burbs get crushed though.

This is why I questioned earlier if the forecasts for several inches actually verify. I think the cutoff will be sharp. You can already see that nowcasting.

[The Iceman]

9 minutes ago, LVLion77 said:

This is why I questioned earlier if the forecasts for several inches actually verify. I think the cutoff will be sharp. You can already see that nowcasting.

Agreed, I think the high risk flood outlook needs to be shifted further N and W with their next update. Models are now converging that the bulk of the heaviest precip will be N and W of 95. The TOR threat has increased significantly though for the 95 area especially if we destabilize this afternoon. If the low does track as far N as the NAM/EURO project, we could have a repeat of the 7/28 tornado outbreak. Pretty impressive parameters depicted on the NAM.

 

[The Iceman]

I will add that the risk of Delaware River flooding has increased with this shift north. If large area's of NE PA and NW NJ receive 4-8" of rain, the river will most likely go above flood stage even if area's further south only see an inch of rain. Right now the forecast is only for the river to hit action stage but I don't think it was based on those area's further upstream receiving that much rain. 

[The Iceman]

HREF tor threat is very impressive around 00z tonight. SE PA and central/south NJ have sig tor means between 3 and 4+. Very impressive for this area:

 

[hazwoper]

47 minutes ago, The Iceman said:

Agreed, I think the high risk flood outlook needs to be shifted further N and W with their next update. Models are now converging that the bulk of the heaviest precip will be N and W of 95. The TOR threat has increased significantly though for the 95 area especially if we destabilize this afternoon. If the low does track as far N as the NAM/EURO project, we could have a repeat of the 7/28 tornado outbreak. Pretty impressive parameters depicted on the NAM.

 

The "high risk" is for excessive rainfall that can lead to flash flooding.  While the areas north look to receive a bit more in the way of total precip, the precip rates in SEPA will be MUCH higher as they occur over a much shorter time frame.  Thus....high risk for flash flooding

[The Iceman]

7 minutes ago, hazwoper said:

The "high risk" is for excessive rainfall that can lead to flash flooding.  While the areas north look to receive a bit more in the way of total precip, the precip rates in SEPA will be MUCH higher as they occur over a much shorter time frame.  Thus....high risk for flash flooding

 Latest HREF also following other guidance showing the heaviest rates will be N and W of 95. The flash flooding threat has significantly decreased this morning for the 95 corridor.

 

 

 

 

 

[The Iceman]

This is the highest 1 hr rates on the HREF as well: heaviest rates up into upper bucks and lehigh valley

 

[Hurricane Agnes]

1 minute ago, The Iceman said:

This is the highest 1 hr rates on the HREF as well: heaviest up into upper bucks and lehigh valley

 

Here's what Mt. Holly had to say about that -

It's gonna probably depend on the position of the front (whether or how far north it lifts as a warm front) and any other dynamics going on in the area that might not be directly related to Ida itself, that I expect is more on the mesoscale level with localized pop-ups that rain themselves out over certain spots.

[RedSky]

Boat rides and life preservers at the Allentown Fair today?

 

[Birds~69]

Pretty much the stagnant cutoff line has been upper mont/bucks. Further W has been raining for a while. I think Reading/Berks will be the sweet spot...

[The Iceman]

who knows, maybe the RGEM scores a coup, but I trust the HREF over any single mesoscale model. 

 

[JTA66]

If nothing else, the RGEM and CMC have been consistent with the heavy rain threat over I-95. But I bet the RGEM is already busting on totals to our NW. 

[Blizzard-on-GFS]

How is no one talking about the tornado threat? Parameters are through the roof 

[JTA66]

12Z GSF also less than 2" for much of the immediate Philly area & surrounding counties.

[The Iceman]

7 minutes ago, JTA66 said:

If nothing else, the RGEM and CMC have been consistent with the heavy rain threat over I-95. But I bet the RGEM is already busting on totals to our NW. 

Considering Scranton is already closing in on 2", it's pretty safe to say it's going to bust low up there. 

[hazwoper]

22 minutes ago, The Iceman said:

who knows, maybe the RGEM scores a coup, but I trust the HREF over any single mesoscale model. 

 

The flash flood threat in SEPA has NOT diminished.  My god what are you looking at?

 

[The Iceman]

19 minutes ago, hazwoper said:

The flash flood threat in SEPA has NOT diminished.  My god what are you looking at?

 

No offense, but can you read? Please quote me where I said it has diminished for all of SE PA? I specifically said the 95 corridor. 1-2" of rain over 3 hours isn't going to cause widespread flash flooding. I posted the HREF maps above, the heaviest rates at 1 hour, 3 hours, and 6 hours are all N and W of the 95 corridor. 

[Kevin Reilly]

• It has not rained a drop since 7:30 this morning in Media Delaware County.  I would think it is pretty simple right now where ever it is not raining right now has the severe thunderstorm and tornado threat.  Heaviest rain clearly stays well north and west of Philadelphia until it collapses down with the severe threat and possible tornadoes towards 2:30 pm or so beyond.  

Currently in Media Delaware County Cloudy 71 

Wildwood is Sunny and 84 with a 77 degree dew point that is high octane stuff.

I am surprised there is no Tornado Watch yet. 

[Birds~69]

31 minutes ago, Blizzard-on-GFS said:

How is no one talking about the tornado threat? Parameters are through the roof 

What is there really to talk about till it happens? Same goes w/T-storms. We all know there's a good chance.

Tornado watch has already been issued for Balt/MD areas and they'll probably extend it into NJ...

A Tornado Watch has been issued for Anne Arundel, Howard, Montgomery, Prince Georges, Carroll, Frederick, Cecil, Baltimore, Harford, Calvert, Charles and St. Marys counties and Baltimore City lasting through 7 p.m.

[Hurricane Agnes]

WPC 11 am update (now extratropical, moving ENE at 25 mph, winds and pressure steady) -

Quote

000
WTNT34 KWNH 011448
TCPAT4

BULLETIN
Post-Tropical Cyclone Ida Advisory Number  26
NWS Weather Prediction Center College Park MD   AL092021
1100 AM EDT Wed Sep 01 2021

...IDA NOW EXTRATROPICAL WITH WIDESPREAD HEAVY RAIN AND AREAS OF
LIFE THREATENING FLASH FLOODING TODAY AND TONIGHT NEAR THE TRACK...
...AN ENHANCED RISK FOR SEVERAL TORNADOES ACROSS PARTS OF THE
MID-ATLANTIC THIS AFTERNOON AND EVENING...


SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...38.3N 80.2W
ABOUT 45 MI...70 KM SSW OF ELKINS WEST VIRGINIA
ABOUT 70 MI...110 KM N OF ROANOKE VIRGINIA
MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H
PRESENT MOVEMENT...ENE OR 60 DEGREES AT 25 MPH...41 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.


DISCUSSION AND OUTLOOK
----------------------
At 1100 AM EDT (1500 UTC), the center of Post-Tropical Cyclone Ida
was located near latitude 38.3 North, longitude 80.2 West. The
post-tropical cyclone is moving toward the east-northeast near 25
mph (41 km/h) and this motion is expected to continue. 

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

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


HAZARDS AFFECTING LAND
----------------------
RAINFALL: Post-Tropical Cyclone 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, lower Hudson and Coastal Connecticut 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
Post-Tropical Cyclone 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 500 PM EDT.

$$
Forecaster Churchill

FORECAST POSITIONS AND MAX WINDS

INIT  01/1500Z 38.3N  80.2W   25 KT  30 MPH...POST-TROP/EXTRATROP
 12H  02/0000Z 40.0N  76.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 24H  02/1200Z 42.5N  70.3W   35 KT  40 MPH...POST-TROP/EXTRATROP
 36H  03/0000Z 44.9N  65.8W   35 KT  40 MPH...POST-TROP/EXTRATROP

 

[RedSky]

Peeps arguing over H2O like snow is hilarious

[Hurricane Agnes]

3 minutes ago, Birds~69 said:

What is there really to talk about till it happens? Same goes w/T-storms. We all know there's a good chance.

Tornado watch has already been issued for Balt/MD areas and they'll probably extend it into NJ...

A Tornado Watch has been issued for Anne Arundel, Howard, Montgomery, Prince Georges, Carroll, Frederick, Cecil, Baltimore, Harford, Calvert, Charles and St. Marys counties and Baltimore City lasting through 7 p.m.

LOL Someone was reading the thread.

SPC is up with TOR Watches.

 

[Hurricane Agnes]

Quote

 

Tornado Watch

TORNADO WATCH OUTLINE UPDATE FOR WT 483
NWS STORM PREDICTION CENTER NORMAN OK
1240 PM EDT WED SEP 1 2021

TORNADO WATCH 483 IS IN EFFECT UNTIL 1000 PM EDT FOR THE
 FOLLOWING LOCATIONS

PAC001-011-017-029-045-071-077-091-095-101-133-020200-
/O.NEW.KWNS.TO.A.0483.210901T1640Z-210902T0200Z/

PA
.    PENNSYLVANIA COUNTIES INCLUDED ARE

ADAMS                BERKS               BUCKS
CHESTER              DELAWARE            LANCASTER
LEHIGH               MONTGOMERY          NORTHAMPTON
PHILADELPHIA         YORK
$$

Quote

Tornado Watch

TORNADO WATCH OUTLINE UPDATE FOR WT 483
NWS STORM PREDICTION CENTER NORMAN OK
1240 PM EDT WED SEP 1 2021

TORNADO WATCH 483 IS IN EFFECT UNTIL 1000 PM EDT FOR THE
 FOLLOWING LOCATIONS

NJC001-005-007-009-011-015-019-021-023-025-027-029-033-035-041-
020200-
/O.NEW.KWNS.TO.A.0483.210901T1640Z-210902T0200Z/

NJ
.    NEW JERSEY COUNTIES INCLUDED ARE

ATLANTIC             BURLINGTON          CAMDEN
CAPE MAY             CUMBERLAND          GLOUCESTER
HUNTERDON            MERCER              MIDDLESEX
MONMOUTH             MORRIS              OCEAN
SALEM                SOMERSET            WARREN
$$

Quote

 

Tornado Watch

TORNADO WATCH OUTLINE UPDATE FOR WT 483
NWS STORM PREDICTION CENTER NORMAN OK
1240 PM EDT WED SEP 1 2021

TORNADO WATCH 483 IS IN EFFECT UNTIL 1000 PM EDT FOR THE
 FOLLOWING LOCATIONS

DEC001-003-005-020200-
/O.NEW.KWNS.TO.A.0483.210901T1640Z-210902T0200Z/

DE
.    DELAWARE COUNTIES INCLUDED ARE

KENT                 NEW CASTLE          SUSSEX
$$

 

[Birds~69]

4 minutes ago, RedSky said:

Peeps arguing over H2O like snow is hilarious

For me it's 6+", flooding, fishing off my front porch, floating cars or bust. I care less about 1-2"...