BULLETIN
Post-Tropical Cyclone Ida Advisory Number  27
NWS Weather Prediction Center College Park MD   AL092021
500 PM EDT Wed Sep 01 2021

...POST-TROPICAL CYCLONE IDA BRINGING WIDESPREAD HEAVY RAIN AND
AREAS OF LIFE THREATENING FLASH FLOODING ALONG AND NEAR TRACK...
...AN ENHANCED RISK FOR TORNADOES ACROSS THE NORTHERN MID-ATLANTIC
AND FAR SOUTHERN NEW ENGLAND THROUGH THIS EVENING...


SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...39.7N 77.0W
ABOUT 35 MI...60 KM E OF HAGERSTOWN MARYLAND
ABOUT 35 MI...55 KM S OF HARRISBURG PENNSYLVANIA
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...ENE OR 65 DEGREES AT 25 MPH...41 KM/H
MINIMUM CENTRAL PRESSURE...999 MB...29.50 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 New England.

Tornado Watches are in effect for much of the Mid-Atlantic,
including portions of Delaware, Maryland, New Jersey, southeastern
Pennsylvania, Washington D.C., Virginia, and far northeastern North
Carolina.


DISCUSSION AND OUTLOOK
----------------------
At 500 PM EDT (2100 UTC), the center of Post-Tropical Cyclone Ida
was located near latitude 39.7 North, longitude 77.0 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 35 mph (55 km/h) with higher gusts.
Little change in strength is forecast during the next 36 hours.

The estimated minimum central pressure is 999 mb (29.50 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 eastern
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. Some 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:

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

TORNADOES: A few tornadoes are likely across portions of the
northern Mid-Atlantic into far southern New England through this
evening.


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


Forecaster Churchill

FORECAST POSITIONS AND MAX WINDS

INIT  01/2100Z 39.7N  77.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 12H  02/0600Z 41.2N  72.9W   35 KT  40 MPH...POST-TROP/EXTRATROP
 24H  02/1800Z 44.2N  67.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 36H  03/0600Z 46.5N  62.9W   35 KT  40 MPH...POST-TROP/EXTRATROP