National Weather Service New York NY
440am EDT Thu Jun 13 2024
Synopsis
High pressure remains in control today, followed by a cold front approaching Friday and moving through Friday night. High pressure returns for the weekend before sliding offshore early next week.
Near Term - Through Tonight
A semi-zonal upper level pattern will be in place today. A southwest flow will become more southerly with localized hybrid sea breeze interaction further east towards afternoon. Look for a good deal of sunshine with just some scattered cumulus likely at 5 to 8 kft as indicated by BUFKIT forecast soundings. A SW flow at 850 mb gets 5kft temperatures climb to about 14 to 16 C. This will yield warmer temperatures region wide, with the warmer temperatures muted slightly further east across the CWA (County Warning Area) due to sea breeze development during the afternoon. Daytime max temperatures will be in the 80s for the most part CWA wide. Expect some middle and upper 80s across the NE NJ metro, with just some middle and upper 70s across SE coastal communities. The winds likely get gusty in the 20 to 25 mph range later in the afternoon for portions of southern Nassau, Queens, and Brooklyn as an Ambrose jet feature attempts to get going.
For Thursday night high pressure will still be in control as it begins to weaken and get further east. Look for partly cloudy to mostly clear skies. A SW synoptic flow regime should keep temperatures above normal at night for the first time in awhile as dewpoints inch a touch higher. Lows should range primarily from the middle 60s to lower 70s.
Short Term - Friday Through Friday Night
Even warmer with a subtle climb in humidity as a S to SW flow increases overall as a cold front approaches from the west. Expect lots of sunshine through the early afternoon, with clouds increasing from west to east with the approach of a cold front. Temperatures are expected to reach the upper 80s to 90 for the NE NJ metro, with mainly 80s elsewhere, and middle and upper 70s across far eastern coastal sections. Convection ahead of the cold front is expected to initiate towards 18 to 20z for the northwestern portions of the CWA, with the activity moving ESE through the late afternoon and evening. Storm Prediction Center has placed the area in a marginal to slight risk of severe thunderstorms, with the slight risk roughly for the western half of the CWA. The main threat with any storms at this time appears to be gusty to damaging wind gusts in any stronger storms. Storm mode appears to be multi-cell clusters with perhaps the storms becoming more of a broken organized line as it gets closer to the metro during the evening. MLCAPE values are expected to exceed 1000 J/kg for far western areas, with bulk shear values in the 35 kt vicinity as this has the chance to be the first widespread thunderstorm activity of the season for a good portion of the CWA. A general weakening trend in any storms is expected as the storms encounter more of a marine environment as they move across the eastern third of the CWA.
The showers and storms should slide to the east by midnight for far eastern sections. A Drier NW flow moves in quickly in the wake of the FROPA, with noticeably lower humidity into Satam with clearing skies.
Long Term - Saturday Through Wednesday
Surface high pressure builds in from the NW behind the exiting cold front on Saturday, centering itself over the area on Sunday as an upper-level ridge begins to build into the area. This ridge remains over the Northeast on Monday before amplifying Tuesday into Wednesday, remaining highly amplified into Thursday.
HEAT! That pretty much sums up the concerns for the long-term forecast. Our first heat wave of the season could be a possibility with multiple days expected to reach the mid-90s with upper-90s possible. The hottest days are expected to be Tuesday through Thursday. Heat index values are projected to be between 95 and 100 at their peak due to higher dewpoints being advected in from onshore flow. This onshore flow, however, could lead to subtle relief for Long Island and parts of coastal Connecticut where winds blowing in from cooler ocean waters may allow their temperatures to be slightly cooler than the rest of the CWA. Heat Advisories may need to be issued as the event nears, if the forecast does not change too much.
850mb warm air advection starts aloft on Monday, but doesn't really become anomalously strong until Tuesday. Its important to note that there is uncertainty with regards to the maximum temperatures. All global model guidance agrees on a highly-amplified ridge over the northeast with warm air advection aloft, but they still differ in magnitude. Expect the forecasted temperatures to change somewhat until the model guidance comes into better agreement. For now, went with a blend of NBM deterministic and NBM 50th percentile. Even the NBM 25th percentile was warmer than the deterministic NBM, so by blending the two together, it has increased forecasted temperatures next week.
A few weak shortwaves embedded within the longwave ridge on Sunday and Monday will help forestall strong heat until Tuesday. The shortwaves will increase cloud coverage somewhat and prevent the ridge from amplifying until Tuesday. This will leave temperatures near normal for the weekend and only slightly above average on Monday.
Marine
A return flow gets established with a south to southwest flow regime today with 2 ft ocean seas getting closer to 3 ft by this evening. With an Ambrose jet attempting to get going late today some occasional small craft gusts cannot be ruled out for the western ocean and towards the Harbor entrance later this afternoon. Overall the S to SW flow results in marginal small craft gusts into Friday ahead of an approaching cold front, especially out on the ocean. The winds then shift to the NW and N Friday night into Saturday with sub small craft conditions prevailing through early next week.
Hydrology
Showers and thunderstorms are expected to bring a round of brief, but locally heavy rain late Friday and Friday evening. Rainfall amounts are expected to average from around a half inch to one inch. Instantaneous rainfall rates will be rather high, but the storms are expected to progress along. Therefore impacts will most likely be limited to minor urban and poor drainage flooding due to the quick movement of this system, with flash flooding appearing unlikely at this time.
Tides / Coastal Flooding
There remains a moderate rip current risk this afternoon for the ocean beaches, and a high risk for most ocean beaches Friday. Eastern Suffolk beaches are expected to have a moderate rip current risk on Friday.
NOAA New York NY Office: Watches - Warnings - Advisories
CT...None. NY...None. NJ...None.
Marine
None.
