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Showing results for tags 'flooding potential'.
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Periods of rain, some of it heavy at times is destined for most of the NYC subforum Friday-Saturday as low pressure develops off the mid Atlantic coast into a vertically deep slow moving cyclone. PW increases at times to near 1.7" in warm advection along the inverted trough Friday then the pinwheeling PWAT circles back around our area Saturday. Gusty northeast-east winds Friday morning to 35 MPH and the constancy of northeast flow this week at the time of the highest tides in Sept should yield at least minor coastal Flooding within 2 hours of high tides Friday and possibly moderate coastal flooding at the highest tide cycle Saturday or Sunday as the backwash of the offshore storm shoots some 45 MPH north-northeast winds down the NJ coast by Sunday morning. The previous 3-4 day rains are attached, and the numbers for this coming one may exceed 6" again in parts of the NYC subforum. If so, where? It's possible, despite all this projected rain, that flooding might be imited to a few small areas. Too early to be sure as of 447PM/27. The EPS has been most aggressive with this system since 9/24 cycles and the 12z/27 EPS mean rainfall is attached. These values are quite high and much higher than the GEFS 12z/27 cycle with the GEPS midway between. If it causes fresh water flooding---where? Not sure this will be very much freshwater flooding except possibly NJ/CT/urban LI. This topic should serve also for the rainfall reports. at 505PM added the tag power outages. If this rainfall develops per the more aggressive 12z/27 EPS mean, rain softened ground from this past weekend combined with new 2+" rainfall may allow spotty power outages due to tree uproots of still fully leaved trees.- 884 replies
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The above hopefully encapsulates the likelihood of two upcoming significant east coast storms. Changes will occur from the some of the attached supporting graphics but we're in line for more significant weather and I'm sort of concerned about flood potential. This time maybe wet snowfall NYC.? Please consider limiting NYC snow enthusiasm with the stats attached from Don, at least until we get Jan 4-5 (if snow is still in the possibilities). It is hoped the Bluewave produced lack of 2" snowfall at CP can be put to bed, but it's possible that next Sundays probable wintry event will shift a little more inland with rain dominating along the coast. The event for the 10th could be brief snow or ice to heavy rain and snow melt, presuming we accumulate anywhere close to the attached 00z/31 EPS prob of 4" axis. Wind damage graphic via the EPS for the 10th... expectations are more of an e-ne wind (nor'easter we hope) for the 7th with gust potential 40-50 MPH along the coast and maybe minor coastal flooding (tide cycles are LOW for this storm). The event around the 10th "may" have stronger winds gusts vicinity 60MPH along the coast and a better chance of coastal flooding (tide cycles 10" higher to start). Power outages possible but impossible to predict without 24 hour confidence on wind gusts/qpf amounts/ptype/temp if and when it snows. This thread was started since I think there is general interest in snow, also flood potential for this weather interested forum. I may comment once/day but it's all yours. OBS for the 6th-7th will go in here. For whatever occurs the 10th...may have to separate out the OBS in a supplemental thread late 9th, but that's 10 days away and at least a portion of these ensemble expectations may be less than out looked through the 00z/31 cycle and therefore less impact and more routine. No guarantees here but definitely worth monitoring. Edited title 1156AM-Jan 6 to include obs and tags added obs and sleet. Edited title 645 AM Jan 8 iso include OBS for Jan 9-10 and removed the ? behind damaging wind.
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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.
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Record daily rainfall values in the POR at POU 2.51-1972 and NYC CP 4.09-1972. Add on as deemed useful Above normal small stream flows from ne NJ into extreme se NYS and w CT, plus multiple small scale modeling of 3-5" and worst case maximum 7+ prompts this topic. WPC has marginal to slight risk excessive and a watch was just issued for the primary concern area at 312PM. It's possible the small scale models have gone overboard, especially the attached FV3 HRW but the SPC MAX amount axis of over 7" and other 12z/6 max axis modeling suggests the primary area of Turn around Don't Drown concern Saturday, if any roads are inundated. Support from PW near 1.6", a 12 hour nearly stationary inflow axis Saturday morning and modeled embedded lightning. The NYC-vicinity max axis may already be forming mid afternoon Friday (monitor radar). Awareness of potential assists mitigating unexpected impacts, planning your day. Again, we'll see what the tallies are but we should not expect as an expansive area of 5+ rainfall as last Friday, though isolated amounts of 5" seem to be within reach somewhere in a 20 miles radius of NYS northward to about 30 miles either side of CT-NYS border. Axis may vary. but multi cycle modeling suggests this is one of primary areas of concern. Self explanatory 12z/6 modeling amounts by 00z/Sunday 8 Oct 2023. There we(RE NO-corrected 10/8) SPC HREF Probs of 1,2,3" in this 12z/6 cycle which suggests modeling errors. Caution but worthy of monitoring.
