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One-3" of rain expected NYC sub forum 1P Wed-1P Thu 12/29/23 and may result in minor small stream flooding Thursday, especially Northern NJ near NYC. Isolated 4" possible.


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Added 12z/26 Blend of models rainfall, the WPC 22z/26 three day rainfall forecast, and a sample from the 18z/26 HRRRX ending 18z/Thursday, which in my mind shows the potential narrow axis of 2-3"+ of rain. If that ends up over the Passaic River Basin,  then minor flooding would resume on parts of the Passaic.  We'll have to wait for reality to know what will result.  There should be an axis of 2-3" rainfall near I95 and it could result in moderate impact for travel Thursday morning. 

This in addition to the overnight-Wednesday morning dense fog impact will mean some difficulties for air and surface travel.  

An additional 0.2-0.6" could fall in the NYC subforum 1P Thu-7P Friday with bands of rain/drizzle in the convergent surface trough region west from the departing low pressure system off New England, and to the north of the weakening upper low moving eastward off the mid-Alantic coast. 

 If 2 inches occurs in Central Park by Friday night, that would push December into the top 5 rainfall (7.12"), and the year to #11 (59.23"). Central Park rainfall seems to have a pretty good chance of exceeding 1.5" but there is always uncertainty on qpf.  

So, another significant rain event is on the way.  The 48 hour qpf from the SPC HREF, HRRR, RRFS from 00z/27 and 12z/27 cycles could be helpful perspectives if and where the potential exists for 3" of rain from this event. 

This thread headline and/or tags may update if the NWS issues flood watches. 

Screen Shot 2023-12-26 at 6.20.03 PM.png

Screen Shot 2023-12-26 at 6.43.10 PM.png

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Flood watch issued by Mt holly 

.FLOOD WATCH IN EFFECT FROM 7 PM EST THIS EVENING THROUGH THURSDAY

EVENING...

 

* WHAT...Flooding caused by excessive rainfall is possible.

* WHERE...Portions of northern Delaware, including the following area, New Castle, New Jersey, including the following areas, Atlantic, Atlantic Coastal Cape May, Camden, Cape May, Coastal Atlantic, Coastal Ocean, Cumberland, Eastern Monmouth, Gloucester,  Hunterdon, Mercer, Middlesex, Morris, Northwestern Burlington, Ocean, Salem, Somerset, Southeastern Burlington, Sussex, Warren and Western Monmouth, and southeast Pennsylvania, including the following areas, Delaware, Eastern Chester, Eastern Montgomery, Lower Bucks, Philadelphia, Upper Bucks, Western Chester and Western Montgomery.

* WHEN...From 7 PM EST this evening through Thursday evening.

* IMPACTS...Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations.

* ADDITIONAL DETAILS...

  - Rainfall totals of 1.5 to 2.0 inches are forecast across the watched area tonight and Thursday with the heaviest rainfall  expected during the evening and overnight hours tonight. Some  areas may see locally higher totals near 3.0 inches. Soils remain saturated due to recent rainfall events and rivers streamflows remain elevated, especially in the Passaic basin.

  - http://www.weather.gov/safety/flood

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2 hours ago, forkyfork said:

it's been pretty much locked into this outcome

qpf_acc-imp.us_ne.png

The system appears to be bypassing NYC.

Rain forecasts have fallen from 2.12" four hours ago to 1.05 " as of now. and may decline further,.Radar suggests much higher rain totals west of the city. 

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8 minutes ago, etudiant said:

The system appears to be bypassing NYC.

Rain forecasts have fallen from 2.12" four hours ago to 1.05 " as of now. and may decline further,.Radar suggests much higher rain totals west of the city. 

Based on? Here's the latest HRRR which actually went up for MBY. It may very well be that the most rain happens west of the city but I don't see a model or prediction that dropped way off. 

image.thumb.png.00b7bb01c474302894412bb57642251a.png

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49 minutes ago, jm1220 said:

Based on? Here's the latest HRRR which actually went up for MBY. It may very well be that the most rain happens west of the city but I don't see a model or prediction that dropped way off. 

image.thumb.png.00b7bb01c474302894412bb57642251a.png

WU now projects 0.77 ' for their day, with another 0.32 " forecast for tomorrow. Thus far no sign of the 'heavy rain' that was anticipated.

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Rainfall totals for December 27th through 11:25 pm include:

Allentown: 1.87" (old record: 1.55", 1930)
Baltimore: 1.63" (old record: 1.21", 1894)
Philadelphia: 1.23"
Washington, DC: 1.20" (old record: 1.16", 1894)
Wilmington, DE: 1.79" (old record: 1.76", 1930)

Guidance and the upstream rainfall totals above suggest that the New York City area remains on track for a general 1.00"-2.00" rainfall with locally higher amounts.

 

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