Bermuda Weather Service Forecast Discussion
For Friday, December 01, 2023
22:00 UTC
FORECASTER - Kimberley Zuill
NOWCAST: This Evening through Tonight
Although high pressure ridging remained in charge today, there was
a small area of SC that just wouldn’t burn off or drift away while
Ci streamed overhead. Light N winds veered to the NE early morning
and have gradually veered to become more ENE. Through tonight they
will continue to gradually veer and the ridging lifts away to the
NE. Models indicate that skies will become partly cloudy at times.
In the cool air flow, temperatures struggled to rise very much today
reaching the highest temp of 69F around noon before cloud cover moderated
it. The humidity remained comfortably in the 60’s making today feel
cool, cloudy and crisp. OPC pegs our offshore seas around 4-5ft,
which aligns well with global wave models. Seas will continue to
ease, becoming mainly slight. No watches/warnings are expected.
AVIATION: VFR conditions RWY12 with ENE 05-08kts winds gradually
veering ESE. No hazards expected. For current airfield information
please visit: http://www.weather.bm/Aviation
SHORT TERM FORECAST: Saturday through Sunday
Upper ridging amplifies over us through Saturday while troughing
advances from the west.
A ridge of high pressure on the surface stretches out beyond Bermuda
past Florida and into the Gulf of Mexico. As it weakens later on
Sunday light SE wind gradually veer SW and increase moderate to strong
during Sunday evening. The veering flow helps further WAA to develop,
with temperatures recovering to near average. Provided the cloud
that lingered nearby today scoots away, Saturday should see plenty
of sunshine then clouds thicken on Sunday as per forecast vertical
profiles, and a couple of pre-frontal/convergent showers are expected
to develop by Sunday evening. Slight seas gradually build slight
to moderate.
WARNINGS: A small craft warning is valid for late Sunday evening
through the night.
LONG TERM FORECAST: Monday through Tuesday
Deep upper troughing moves into the area during the period, with
an upper trough axis passing by early on Tuesday morning. This corresponds
to a deepening area of low pressure to the distant N which gradually
steers a front across the local area. Winds ahead of the front will
increase and based on the last couple of model runs, the forecast
has been nudged up to 20-30 gusting 40 knots in the early hours of
Tuesday, these higher gusts are expected in and around showers especially.
There is still some discrepancy as to how quickly the winds will
veer NW, as some models indicate a slight sympathetic ridging followed
by a secondary trough. Others have a broader boundary and some even
suggest fragmentation to our south (the creation of the “Bermuda
Gap”!) regardless at some point during mid Tuesday meaning winds
will veer NW and ease to moderate. Showers are expected to break
out later Monday, mainly overnight into Tuesday morning, when they
clear out rapidly with FROPA. QPFs are quite wide ranging as some
of the model guidance brings deep convection overhead. However, a
good middle ground appears to be around 0.5” for the moment. Instability
indices show a marginal risk of thunder Monday night. Although this
is not yet stated in the detailed forecast products, this will need
to be monitored closely with further model guidance as not only will
it need to be incorporated into the forecast, but a thunderstorm
advisory may also be required. Temperatures ahead of the front may
peak as high as 24C/75F, before cooling off thereafter. All models
indicate a rapid transition of a small region of high pressure during
the remainder of Tuesday and overnight, however the synoptic pattern
becomes quite messy for Wednesday as subsequent forecasts will detail.
Seas build moderate to rough on Monday and only begin to abate later
Tuesday, but only briefly.
WARNINGS: A small craft warning will be needed for the long term
period.