597
FXUS61 KBTV 040444
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
1244 AM EDT Sat May 4 2024

.SYNOPSIS...
Dry and seasonably warm weather will continue across the region to
start the weekend, with the exception of a few possible showers
across northern New York on Saturday before widespread precipitation
returns for Sunday. A period of warmer and sunnier conditions
are expected for the start of the week, with more unsettled
weather returning by the middle of next week.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 1238 AM EDT Saturday...Southerly flow is preventing
temperatures from falling quickly across the Champlain Valley
and parts of northern New York so had to bump them up a little.
Rain showers are trying to enter the St. Lawrence Valley but
most of them have not been able to reach the ground so trimmed
PoPs slightly. Clouds are slowly lowering from west to east and
this should continue for the rest of the night. Overall, the
forecast is mostly on track so all the edits were minor.
Previous discussion follows

Previous discussion...Surface high pressure and upper level
ridging across the region haver made for a pleasant Friday
afternoon, with dry conditions and seasonably warm temperatures.
As we head into the evening, the upper level ridge axis will
continue to shift eastward,although dry conditions will persist.
There will be increasing high clouds across the region
overnight associated with a frontal boundary to our west. Unlike
the last few nights, increased clouds and winds will inhibit
any fog development across the region. A light rain shower or
two may be possible across northern New York early Saturday
morning as the frontal boundary moves closer, but any measurable
precipitation would be minimal. Overnight low temperatures will
be mild, in the 40s to low 50s.

Saturday will be another pleasant day as we remain under the
influence of high pressure, with mostly dry weather. Temperatures
will warm into the 60s to near 70 in some of the broad valley
locations, with high clouds remaining overhead. Dry weather will
continue through most of Saturday night, with the latest guidance
continuing to trend on the drier side for Saturday night with a
strong ridge axis in place. Another mild night is expected, with
temperatures in the 40s to low 50s ahead of approaching widespread
precipitation on Sunday.

&&

.SHORT TERM /SUNDAY NIGHT/...
As of 303 PM EDT Friday...PWATs rise to around 1.5 standard
deviations above normal on Sunday as moisture with Gulf of Mexico
origin looks to overspread the region. Upper level pattern shows a
stout omega block shifting east of our area into Maine, increasing
shower chances and coverage on Sunday. However, organized convection
is not expected as the main jet energy associated with the shortwave
trough moving eastward from the Great Lakes is diverted into Quebec.
As a result, the main trough axis does not approach North Country
until sometime next Tuesday. This will be discussed in the long term
section of the forecast discussion. Indeed, forecast soundings show
a lack of surface-based instability, so showers with brief locally
heavy downpours look to be the main risk. While there could be
embedded thunder due to elevated instability, no organized
thunderstorms are anticipated.

PoPs do increase to the likely category with scattered to perhaps
numerous showers on Sunday. While there would likely be widespread
wetting rainfall, QPF amounts are quite manageable in the 0.1 to 0.3
inch range with locally higher amounts. Indeed, the MMEFS shows none
of our area rivers going into action stage. Sunday will be quite a
bit cooler than Saturday, with highs only in the 50s with low 60s
possible if there are breaks in the rain or clouds. In addition, a
40-50 kt 925mb southerly low level jet overspreads the region on
Sunday. NAEFS situational awareness ensemble table shows the v
vector wind rising to almost 2.5 standard deviations above normal,
so it will be breezy if not blustery. A mitigating factor is that
the waters of Lake Champlain is still quite cold with water
temperatures still in the low to mid 40s, which is almost isothermal
to the forecast 925mb temperatures in the +5 to +8C range. That
could reduce the mixing potential in the boundary layer. So have
mostly kept wind gusts in the 30 to 35 mph range across the
Champlain Valley despite the southerly wind component being
anomalously strong. Overall, no overall hazardous weather to speak
of but Sunday does look to be a less than ideal day for outdoor
activities. Heading into Sunday night, showers taper off and the
boundary layer looks well mixed enough to preclude widespread fog
development. Temperatures stay quite mild in the mid 40s to low 50s.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 303 PM EDT Friday...The overall weather pattern heading into
the first full week of May can be described as unsettled with no
real significant warm up or impactful weather. Unsurprisingly, the
CPC 8-14 day temperature outlook favors near normal temperatures and
leans towards above normal rainfall. For reference, typical highs
for North Country in early May are in the low to mid 60s, while
average overnight lows are in the mid 30s to low 40s. The upper
level pattern features a positively tilted omega block sandwiched
between an anomalously deep trough across the Rockies/northern Great
Plains and another trough over eastern Quebec/Newfoundland. H5
height anomalies favor a period of widespread showers and
thunderstorms in the Tuesday/Wednesday time frame, as positive H5
height anomalies give way to near normal values. Depending on the
timing of the associated surface cold front, ingredients may exist
for a few stronger storms. Taking a first look at ensemble guidance
probabilities, it does look like the better chance for organized
convection is across our southwestern zones, with more garden
variety thunderstorms towards Vermont and the Champlain Valley. This
makes sense from a synoptic perspective as the aforementioned
positively tilted omega block may not be that easy to dislodge. As a
result, our region only gets a piece of weak shortwave energy that
peels off from the base of the northern Great Plains upper low and
deamplifies as it tracks towards southern Ontario/Quebec. In simple
terms, our region gets a glancing blow in terms of dynamical forcing
and as a result, the odds for any stronger convective storms greatly
diminish. While we are still 4 days away, model trends are favoring
an unsettled but benign pattern for North Country in the upcoming
week.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
Through 00Z Sunday...VFR conditions will prevail through the
forecast period, with the possible exception of brief MVFR
conditions if scattered showers are sufficiently heavy at MSS
and SLK. The timeframe for precipitation is mainly in the 05Z to
11Z period for MSS and 07Z to 12Z period for SLK, with showers
expected to peter out as they move farther east. Terrain driven
flow at the start of the period, mainly 3 to 7 knots, will trend
southerly after 06Z, and then southeasterly after 18Z. Ceilings
will tend to lower with time but remain at VFR levels through
the period.


Outlook...

Saturday Night: VFR. Chance SHRA.
Sunday: Mainly MVFR, with areas VFR possible. Definite SHRA.
Sunday Night: Mainly MVFR, with areas IFR possible. Chance SHRA.
Monday: Mainly VFR, with local IFR possible. Slight chance SHRA.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. Slight chance SHRA.
Wednesday: VFR. Likely SHRA.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...Kremer
NEAR TERM...Kremer/Myskowski
SHORT TERM...Chai
LONG TERM...Chai
AVIATION...Kremer/Kutikoff