Weather with Bill Evans

National Weather Service New York NY Friday June 13, 2025 Cold front south of the area will continue to move south today. However, a slight chance for showers and isolated thunderstorms are possible today, mainly for southern and western portions of the forecast area as they form along the cold frontal boundary aloft. This can be seen in recent radar imagery, where showers have been developing along a boundary that crossed eastern Long Island and the sound earlier last night. Despite an easterly flow developing, have mentioned isolated thunder with a few hundred J/kg of elevated CAPE noted in some of the forecast sounding across western Long Island, NYC, and northeast NJ this morning into the afternoon. Lower Hudson Valley looks to be in stable enough environment where just showers are expected there. There is a fair amount of uncertainty with exactly where precipitation occurs this morning into the afternoon given various CAMs solutions, but it seems the most likely areas are the aforementioned areas, due to their proximity to the surface cold front, but probably more importantly the front aloft. Temperatures will be closer to normal today, with highs ranging from the middle 70s to around 80. Low pressure is expected to form along the frontal boundary tonight over the mid-Atlantic states and track northeast along the boundary into Saturday morning, being located somewhere south of Long Island by late morning Saturday into Saturday afternoon. A period of moderate to briefly heavy rain is possible during this time frame, especially as PWAT values increase to 1.50" to 2.00". The ECMWF and NAM are the most bullish on rainfall, with over an inch expected during this 12 hour period, mainly across Long Island. Think that these values are too high and may be suffering from convective feedback issues. Tried to come to some sort of consensus among the models, and have a storm total ranging from a tenth of an inch (southwest CT) to just over half an inch (NYC and Long Island) from late tonight through the day Saturday. Localized amounts of inch are possible given aforementioned PWAT values, but flooding is not expected at this time. The most likely outcome would be minor nuisance and poor drainage flooding, mainly for Long Island. Rain tapers off Saturday afternoon and into Saturday night as high pressure from southern Canada builds in. Unsettled pattern continues for Sunday as another area of low pressure forms near the Ohio river Valley and heads east. As it heads east, the front edge of the precipitation field may affect western and souther portions of the forecast area late Sunday into Sunday night, however precipitation is not expected to be as widespread as compared to Saturday. With rain and clouds expected for Saturday and Sunday, temperatures are expected to run below normal for this time of year. Highs are not expected to climb out of the 60s. Lows will be in the 50s to around 60. Main upper level jet stays north of the region for the time period of next week Monday through Thursday night. The main upper level westerlies get relatively close, not that far north of the region Wednesday into Wednesday night with a shortwave trough passing north of the region. The westerlies increase again late in the week when a stronger shortwave approaches the region. At the surface, high pressure southeast of Nova Scotia gradually weakens Monday into Monday night. One wave of low pressure passes well south of the region along the stalled front Monday into Monday night. Another wave of low pressure passes south of the area along the front Tuesday night into early Wednesday. For Monday through early Wednesday, unsettled weather pattern remains with chances of showers and cooler than normal temperatures. Monday is forecast to be well below normal once again as highs only near 70 are expected for much of the region. Highs forecast on Tuesday warm up but are still a few degrees below normal, mostly mid to upper 70s. Surface winds transition from being more easterly Monday to more southerly Tuesday. Eventually by mid week, stronger trough in the Central US shifts the pattern for the local area downstream as a stronger low pressure system develops. The frontal boundary eventually lifts back north on Wednesday as a warm front. The warm front eventually lifts north of the region Wednesday night and then the local area will be fully in a warm sector Thursday. Meanwhile, an associated cold front will be approaching from the west. Increasing SE to S winds Wednesday and SW winds Thursday will increase low level warm air advection. Temperature continue on their rising trend Wednesday into Thursday. Dewpoints will be on the rise as well. Airmass will be getting more warm and humid. Max temperatures WEdnesday are upper 70s to lower 80s for most locations and 80s to near 90 for much of the region on Thursday. Those max temperatures near 90 Thursday are within parts of NYC and Northeast NJ as well as Lower Hudson Valley with corresponding heat indices reaching low to mid 90s. Chances for showers remain Wednesday through Thursday but thunderstorms will be possible as well with the increasing low level instability from the greater surface warmth. Some thunderstorms could be strong especially with the approach of the cold front when more shear with those greater westerlies could enable even for a few severe thunderstorms with enough shear and CAPE. There is uncertainty with model locations and fronts and even more uncertainty with timing of convection. Therefore exact and refined time windows for showers and thunderstorms will be difficult to determine at this time. Sub advisory conditions are anticipated for all waters through the first half of the weekend. Ocean seas generally hold at 2 to 4 ft with a relaxed pressure gradient and a light onshore flow. Marginal SCA seas are possible for the central and eastern ocean zones late Saturday night into Sunday morning. For the long term marine forecast, conditions are forecast to remain below SCA thresholds on all waters Monday through Tuesday night. The pressure gradient on average is expected to remain weak allowing for relatively less wind and thereby less amplitude waves. A tenth to just over a half inch of rainfall is expected from tonight through Saturday. Isolated amounts over an inch are possible, especially across Long Island. There is the potential for moderate to briefly heavy rain, but no flooding is expected at this time. The most likely outcome would be minor nuisance flooding. No hydrologic impacts expected Monday and Tuesday. Thunderstorms mid to late next week will be capable of producing locally heavy downpours and thereby minor flooding of low lying, poor drainage and urban areas. The rip current risk is low on Friday with a light easterly flow and limited swell. There is a moderate rip current risk on Saturday with increasing easterly flow and building seas 3 to 4 ft.