Key messages
- 1) A warm front brings showers early today, with a strong cold front
What Has Changed
No significant changes from the previous update.
Key Messages
bringing a line of heavier showers and a few strong, to possibly severe thunderstorms briefly during this evening. Any storms have the potential to bring strong, gusty winds. A few isolated damaging winds gusts are possible with any severe storms.
2) The coolest air mass of the season so far moves in this weekend along with Gusty NNW winds during Saturday.
Key Message 1
A warm front pushes in from the southwest through the morning and should exit northern and northeastern sections by early afternoon. The rain during the first half of the day will be a result of warm air advection at and just above the 850 mb level. The winds start out from the SE, then turn southerly, before going SW during the afternoon. Some gusty winds at times later today are expected closer to the water across eastern coastal sections. Dewpoints will be rather elevated for this time of year getting well into the 60s in many places, especially further east on a SW flow. If clouds can scatter out enough behind the departing warm front for roughly a 3 hr period or so later in the afternoon then instability would be a bit higher. This will be critical in supplying fuel to any storms attempting to initiate along the cold front late in the day. The region gets into the warm sector for about a 5-6 hr period, but any additional sunshine would lead to a touch more instability which is the question with regard to the convective / severe potential. Long hodographs with low-top convection and mid level lapse rates around 6 C/km may lead to strong gusty winds. If any storms can take advantage of any additional instability then a few isolated damaging wind gusts cannot be ruled out with the strongest of any storms. SPC has placed most of the region in a Slight risk of severe weather, with far northeastern sections in CT in a Marginal risk. Wind is the primarily threat with any storms in the low CAPE / high shear environment.
CAM guidance is in excellent agreement with regard to the timing of any convection along the cold front as the guidance is in lock step with regard to the timing of the frontal passage. Which now stands around 22z for far western sections, around 23-0z for the metro, and closer to 02z for far eastern sections. Thus, the front moves very quickly through the area in a span of about 4 hours from west to east. With the passage of the front the rain and any storms will end quickly as the winds switch quickly to the WNW, and more NW later at night. Drier air works in for western portions of the area, but will take longer to get into eastern sections. The upper trough axis lags behind the surface features quite a bit, thus lingering rain and showers is expected east of the metro and for the eastern third of the area towards and after 06z to about 12-13z Saturday morning for far eastern sections.
Key Message 2
The coolest air mass of the season so far moves in this weekend along with Gusty NNW to N winds developing towards mid to late Saturday morning and continuing through the afternoon. Winds may gust up to 35 mph in some locations. Thus a dry, blustery and much cooler day despite developing sunshine. Temperatures are only expected to reach the lower and middle 50s during the day. Widespread 30s to around 40 are expected for lows Saturday night. Some far northern sections may get down to freezing. Some temperature moderation is likely towards late in the day on Sunday with daytime temperatures recovering a little into the upper half of the 50s with much lighter winds as the pressure gradient relaxes and high pressure settles over the area during the afternoon.
Aviation /09Z Friday Through Tuesday/
Warm front lifts through later this morning, followed by a cold frontal passage late this afternoon into early evening.
MVFR cigs overspread the area early this morning, possibly lowering to IFR through 12Z. Scattered showers are also moving through, and may restrict vsbys at times. The showers taper by late morning, but conditions likely remain MVFR into the afternoon, before possibly improving to VFR for NYC and LoHud Valley terminals by 18Z. Eastern terminals may follow a short time later, but it also remains possible they remain MVFR through the day. A line of showers and thunderstorms moves through with the frontal passage from 21Z to 01Z Saturday.
SSE flow around 10 kt early this morning veers S then SW into late morning, with gusts toward 20 developing. Gusts continue into the afternoon 20-25 kt. After the frontal passage, winds shift W then NW Friday evening into the overnight.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of changing flight categories this morning and later today could vary by an hour or two. Amendments likely.
A few strong to severe thunderstorms are possible after 21Z. Isolated gusts 40 to 50 kt are possible with any thunderstorm.
Chance of MVFR in showers early Saturday AM.
Outlook For 06Z Saturday Through Tuesday
Late tonight: Mainly VFR, possible MVFR -SHRA. NW winds G25kt.
Saturday: Mainly VFR. NW winds G25-30kt, diminishing in the evening.
Sunday-Tuesday: VFR.
Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90
Marine
Conditions ramp up this morning with small craft conditions quickly developing for most waters in a southerly flow, especially for the afternoon when the winds turn more SW ahead of an approaching cold front. The western LI Sound and NY Harbor may only see a few occasional gusts of 20 to 25 kt today. The cold front passes through this evening with the winds becoming W, then NW late tonight and into Saturday morning. A period of gales remains possible across the ocean waters for the late morning and afternoon on Saturday. Small craft conditions will likely linger for Saturday night before sub advisory conditions return briefly for a good portion of Sunday. Seas however become somewhat elevated towards Monday morning with a prolonged period of small craft seas and gusts hovering near 25 kt at times out over the ocean with the potential for an offshore storm leading to gusty NE winds at times into the mid week.
Okx Watches/Warnings/Advisories
CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from 11 AM this morning to 6 PM EDT this evening for ANZ331. Small Craft Advisory from 8 AM this morning to 6 PM EDT this evening for ANZ332-340-345. Small Craft Advisory from 8 AM this morning to 6 AM EDT Saturday for ANZ350-353. Gale Watch from Saturday morning through Saturday afternoon for ANZ350-353-355-380-383-385. Small Craft Advisory from 11 AM this morning to 6 AM EDT Saturday for ANZ355.
DISCUSSION...JE AVIATION...DR MARINE...JE