textproduct: New York

WHAT HAS CHANGED

The threat for flash flooding continues today, although the exact location of the heaviest rainfall/greatest flooding still remains somewhat uncertain.

KEY MESSAGES

1) Multiple rounds of heavy rain and thunderstorms through late Monday could lead to scattered to numerous instances of flash flooding. Flooding may be locally significant.

KEY MESSAGE 1

Flood Watch remains in effect through tonight.

A stationary front will remain south of Long Island today. Multiple rounds of heavy rain, along with embedded thunderstorms are expected as a series of shortwaves ride along the boundary through tonight.

Showers along with embedded thunderstorms are expected to continue through much of the day today as better upper level support/jet energy moves into the region. Conditions remain favorable for torrential rainfall rates/flooding today due to a humid air mass over the region. PWATs remain around 2 inches areawide today, although PWATs of 2+ inches may periodically advect into the southern portion of the area, which is higher than daily max sounding climatology values. Some of the 00z forecast models have indicated PWATs maxing out closer to 2.4 inches.

With an easterly flow, mainly parallel to the frontal boundary, training of storms will be likely with potential for backbuilding. 00Z HREF probabilities for 3 inches of rain or more in 3 hours highlights portions of the NE NJ, NYC and Long Island in a 30 percent contour for this evening into tonight, which is typically a good indication of flash flooding potential for this area.

As a result, WPC has placed NYC, Long Island and southern CT in a moderate risk for excessive rainfall today.

In terms of rainfall amounts, storm total QPF through Tuesday will likely range between 2 and 3 inches with locally higher amounts of 4+ inches. Rainfall rates will likely be 1-2 inches per hour with locally higher rates possible. The main area of uncertainty with the forecast is where the highest rainfall totals and resulting flooding will occur and will depend on the exact placement of the frontal boundary.

Flooding impacts would be highest in urban and poor drainage areas in addition to the most responsive rivers/creeks/streams.

OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY

Tuesday: IFR and showers, mainly early. Slight chance of thunder. Improving to MVFR in the afternoon with lower chances of showers. VFR eventually returns at night.

Wednesday: VFR.

Thursday: Possible showers and thunderstorms, mainly at night. Brief MVFR to IFR possible, otherwise mainly VFR.

Friday: Chance of SHRA/TSRA with MVFR to IFR possible. Otherwise, mainly VFR.

MARINE

A Small Craft Advisory remains in effect for Long Island Sound, Fire Island Inlet to Montauk Point, and the South Shore Bays from Jones Inlet through Shinnecock Bay today and tonight. East to east-northeast wind gusts to 25 to as high as near 30 knots and waves of 4 to periodically 5 feet are expected during this time. Waves may remain elevated into Tuesday.

Rip Currents: Increasing E flow should increase the risk back to moderate today. Flow continues to shift out of the NE but given persisting E/SE swell a moderate is maintained for Tuesday.

OKX WATCHES/WARNINGS/ADVISORIES

CT...Flood Watch through late tonight for CTZ005>012. NY...Flood Watch through late tonight for NYZ067>075-078>081- 176>179. NJ...Flood Watch through late tonight for NJZ002-004-006-103>108. MARINE...Small Craft Advisory until 6 AM EDT Tuesday for ANZ331-332-335- 340-345-350-353.