textproduct: Burlington

WHAT HAS CHANGED

As of 234 PM EDT Saturday...

No significant changes were made with this forecast package.

KEY MESSAGES

As of 234 PM EDT Saturday...

1. This afternoon's rain moves out this evening, but additional showers are expected tonight into Sunday morning.

2. Brief ridging combined with an upper trough will keep Monday and Tuesday chilly but mainly dry.

3. Gradual warming through mid to late next week to near normal temperatures with a few chance for light rain showers.

DISCUSSION

As of 234 PM EDT Saturday...

KEY MESSAGE 1: Rain has spread across mainly central and southern VT this afternoon, with a few showers lifting into the eastern Adirondacks and portions of the Champlain Valley. This precipitation will continue to shift eastward through the day, with any additional rainfall less than a quarter of an inch. Our next round of showers arrives this evening into the overnight with a prefrontal trough and cold frontal passage. This activity can be seen on upstream radars, moving across lower Michigan and into Ontario. These showers will arrive into the St Lawrence Valley before midnight, and there could still be enough elevated instability for a rumble of thunder or two. Showers should wane in coverage as they move eastward into Vermont late tonight/early Sunday. However, the cold front will quickly follow Sunday morning, bringing a renewed chance for additional showers, especially across central and eastern VT. Much drier air follows the cold front, and precipitation should quickly end by late morning/early afternoon, so Mother's Day won't be a complete washout. However, expect good mixing behind the front as well due to cold air advection and clearing skies, allowing winds to become gusty during the afternoon. Dewpoints will fall as well, with minimum relative humidity values dropping into the 25 to 35 percent range. Winds will be gusting to around 20 mph, though the highest gusts will be in northern NY, which will also see the highest relative humidity values due to cooler daytime temperatures. Highs will range from the mid/upper 50s in west of the Champlain Valley, while 60s will be much more common from the Champlain Valley eastward.

KEY MESSAGE 2: Surface high pressure will edge into the area Monday and Tuesday, ushering in a cool and dry airmass. However, an upper shortwave trough will swing overhead on Monday. Much like what we saw on Friday, the cold pool aloft combined with daytime heating will lead to steep low level lapse rates. While this should generally lead to daytime clouds, there could be just enough moisture and instability to allow afternoon showers to develop, particularly over northern NY. This upper trough will give way to ridging by Tuesday though, so no precipitation is expected. Both days will be chilly, with highs around 10 degrees below normal; most spots should top out in the 50s. Sunday night and Monday night will feature frosty conditions as lows dip into the low to mid 30s. Frost Advisories may need to be issued, especially since the growing season for the St Lawrence Valley and all of Vermont except the Northeast Kingdom officially starts on May 11.

KEY MESSAGE 3: Early week surface ridging accompanied by upper level troughing will start the extended on a cooler note, before more persistent ridging under southwest flow gradually warms the region to near normal temperatures by late next week. Cool and dry conditions will start off the extended Tuesday night with chances for Frost across eastern Vermont as surface high pressure aided by 540mb thickness lines will drop temperatures into the low to mid 30s in eastern Vermont. The climatological growing season for eastern Vermont (outside of the NEK), begins Monday May 11th, so Frost headlines may be needed if cloud cover becomes conducive for radiational cooling.

Into the middle and late portions of next week, strong ridging across the western CONUS will trend our flow pattern towards troughiness with an upper level low still in place across the Hudson Bay. There is good agreement in a long wave ejecting out of the Great Lakes which should help dislodge the upper low, however, the evolution of the surface system remains somewhat uncertain. Models are not handling the deepening of the long wave trough well, with the duration of any shower activity in question. A blocking high in the north central Atlantic will delay the propagation of a surface low Wednesday into Thursday, however, models such as the EPS keep cyclonic flow and shower activity into Friday as the low stalls and becomes embedded in a baroclinic zone off the New England coast. The GEFS/GEPS are a bit more progressive with the low also a bit north which would reduce the chances of the system occluding over New England. Behind the mid to late week system, ridging should make its return for the weekend with warming temperatures to at or perhaps above normal with GEFS 925mb temperatures to 15C, supporting temperatures in the 70s. The one caveat would be if the mid to late week system becomes blocked, temperatures may be cooler than currently forecast due to shower activity, northeast cyclonic flow and clouds for the weekend. For now, we can hope for a warm, and drying weekend.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

Through 00Z Monday...MVFR CIGs have become more pervasive than expected. The result will be to keep CIGs lower through the overnight hours, until the frontal boundary moves into the region to increase mixing disrupting current low level stability. Added some LLWS to MSS and SLK 03-08Z as the front moves in and through. The boundary is favored to weaken as it tracks eastward mainly due to its passage through the night time hours. Widespread prob30 for light rain showers is favored 05-12Z with more showers possible 12-18Z as CIGs become increasingly VFR. VFR conditions will prevail after 18Z behind the front as drier air moves in. Flow will increase after 12Z with gusts 20-30kts possible for MSS where terrain and prevailing direction align. Elsewhere, gusts 15-20kts are expected.

Outlook...

Sunday Night: VFR. NO SIG WX. Monday: VFR. Slight chance SHRA. Monday Night: VFR. Patchy frost. Tuesday: VFR. NO SIG WX. Tuesday Night: VFR. NO SIG WX. Wednesday: Mainly VFR, with local MVFR possible. Chance SHRA. Wednesday Night: MVFR. Chance SHRA. Thursday: Mainly MVFR, with local IFR possible. Chance SHRA.

MARINE

A Lake Wind Advisory is in effect this afternoon and overnight. South winds of 15 to 25 kt will continue through the remainder of this afternoon. They will briefly subside this evening, then pick back up overnight. Waves of 2 to 4 feet can be expected.

BTV WATCHES/WARNINGS/ADVISORIES

VT...None. NY...None.