National Weather Service New York NY
732am EDT Fri Jun 14 2024
Synopsis
A cold front will move through the area this evening with high pressure building in from the northwest behind it. High pressure becomes centered over the area Sunday morning and moves offshore by Sunday evening. The high remains in control through late next week.
Near Term - Through Tonight
The forecast remains on track this morning. A few isolated showers have popped up just south of Long Island, so have continued the slight chance of showers for early this morning. This activity will likely be confined to Long Island.
High pressure has now shifted well offshore as a cold front approaches from the west. The front is currently over the Great Lakes and approaching western NY as the associated surface low tracks through southeast Canada. Aloft, multiple shortwave troughs are rotating around the broader trough over the northeast US.
We are still on track to potentially see strong to severe thunderstorms this afternoon and evening. The latest Storm Prediction Center outlook remains similar to the previous outlook. NYC north and west are in a slight risk and the rest of the area is in a marginal risk.
Before any potential severe weather, showers will be possible early this morning, mainly across Long Island. This looks to be associated with weak warm advection ahead of a midlevel shortwave. Then, multiple CAMs show some convective activity entering the Lower Hudson Valley by mid morning. This activity looks to spark up north and west of our area associated with a weak shortwave that will pass north of us and a pre-frontal trough. Not too confident in this activity and although thunder is possible, any storms will likely stay below severe limits.
Later this afternoon into the evening is the most likely timing of any severe weather as a stronger shortwave approaches aloft as well as a cold front at the surface. A moist southerly flow will bring dewpoints into the upper 60s by the afternoon and mostly sunny skies will help bring surface temperatures up to the mid to upper 80s for most. This will result in SBCAPE values around 1000-1500 J/kg for NYC north and west. 0-6 km shear is expected to max out around 35 to 40 kt, also for NYC north and west. This environment can support severe thunderstorms capable of producing damaging winds and large hail. While discrete convection cannot be ruled out, the most likely form will be clusters or a broken line. Given the moist environment and skinny CAPE profile, heavy rain is also possible in any showers or thunderstorms. See hydrology section below. It is possible the severe threat becomes limited by any activity that happens earlier in the day and will depend on if/when that occurs and if we can destabilize after that. The severe threat is also lower across eastern areas as the storms will likely weaken as they reach the marine environment as is usual this time of the year.
The area will likely be dry by the early morning hours on Saturday.
Short Term - Saturday Through Sunday Night
After an active Friday, the weekend is expected to feature plenty of sunshine and quiet weather. High pressure slowly builds in behind the departing cold front as heigheights rise aloft with an upper level ridge building over the eastern US. The airmass that will build in will be cooler and drier. Dewpoints will be in the 40s and 50s both days, withs highs in the 70s to low 80s. This will give the air a comfortable feel. We could actually drop to the upper 40s at the usual cool spots Saturday night as radiational cooling conditions look ideal.
The center of the high moves offshore by Sunday evening and a return flow sets up.
Long Term - Monday Through Thursday
**Key Points**
* Increasing confidence in a prolonged heat wave mid to late next week. Heat indices may approach or exceed 100F at times, especially Wednesday through Friday.
* Heat indices greater than 90 are expected as early as Tuesday, gradually expanding and increasing through the end of the week.
Surface high pressure gradually shifts overhead and offshore on late Sunday as a large mid and upper level ridge continues to build over the Eastern CONUS. The surface high pressure positions itself over the Western Atlantic, allowing for a persistent southwest to south flow over the area, advecting both lower level moisture and warm air into the area.
The building ridge amplifies further into the middle to end of the week, allowing for the development of a close to 600dm ridge over the Northeast US and SE Canada. A ridge of this strength for mid- late June over the area would be highly anomalous, though there still remains uncertainty as to how strong it becomes. Temperatures at 850mb from Tuesday through at least Friday will be 18-21C allowing for surface temperatures to reach into the 90s and possibly approaching 100 degrees toward the end of the week for western portions of the area away from the immediate coastline. Heat indices may be slightly higher given a SW/S flow advecting higher moisture into the area. While details as to the extent of the heat will come into focus as we approach early next week, this will very likely be the first heat wave of the season with heat headlines eventually being needed for at least a portion of the area.
Given the potential duration of the heat, it'll be important to take precautions to protect one's health, particularly those without effective cooling and/or adequate hydration. Some heat-sensitive industries and infrastructure will likely be impacted by the extent of this heat as well.
Marine
A southerly flow will occasionally gust up to 25 kt this afternoon, otherwise winds and waves are expected to remain below SCA (Small Craft Advisory) conditions through early next week.
There is potential for showers and thunderstorms this afternoon and evening, with the possibility of some being strong to severe.
Hydrology
The entire area is now in a marginal risk of excessive rainfall. Expecting mostly minor urban poor drainage flooding, but localized flash flooding cannot be ruled out. Although rain will be heavy at times, the progressive nature of the thunderstorms is expected to keep flooding more minor. Probabilities of seeing 1 inch in 1 hour remain low. Average storm total rainfall amounts will be between half an inch and 1 inch, with locally higher amounts possible.
Tides / Coastal Flooding
There is a high risk for rip current development along Atlantic facing beaches today with southerly flow 15 to 20 kt along the shoreline and surf up to 4 ft expected.
Conditions begin to improve by Saturday, with a moderate risk forecast as winds shift offshore.
NOAA New York NY Office: Watches - Warnings - Advisories
CT...None. NY...High Risk for Rip Currents through this evening for NYZ075-080-081- 178-179. NJ...None.
Marine
None.
