Bermuda Weather Service Forecast Discussion
For Tuesday, March 28, 2023
09:00 UTC
FORECASTER - Anton Wiltshire
Nowcast: Today through Tonight
Upper level cloud continued to stream over the area as low cloud
occasionally moved in overhead. Cloud bases generally were in the
800-1000ft range with ceilings dropping to 800ft at times during
the night. Moderate westerly winds backed west southwesterly through
the night increasing 15-20 knots while maintaining its direction.
A warm front is currently just to the north of the area which brings
the increased cloudy conditions through the area. Despite clouds
rolling through, no showers were reported at the airfield. As the
low pressure system moves to the northeast, the warm front will lift
away from BDA and the island will slip into the warm sector for a
while before the cold front comes barreling towards us. This will
bring an ease to the cloudiness for a while and allow temperatures
to climb into the low 70s F. In the upper levels, a near zonal flow
is dominant aloft which keeps the neutral pattern. Most of the sferics
to the northwest gradually diminished during the night with only
a couple strikes observed during the morning. As the cold front moves
overhead later, GFS model QPFs are still in the 2-2.5mm range, EC
near 5mm and UK near 4mm. A look at the latest satellite GOES IR
imagery shows mostly cloudy skies across the area as cloud continue
to drift in from the west/northwest with thicker cloud passing within
150-200km to the north. The latest radar imagery shows the area echo
free within 100km and a few moderate echoes further north of the
island. The surface analysis at 0600Z shows a low pressure system
to our north extending a frontal boundary to the northeast and high
pressure holding to the south. West southwesterly to southwesterly
winds 16-22 knots will decrease later this afternoon then veering
west 10-15 knots by evening. Winds may become variable overnight
for a while. The latest OPC analysis indicates seas near 6-7ft, which
aligns well with global models and seas will maintain that moderate
state.
WARNINGS: A Small Craft Warning is valid this morning through this
afternoon for winds in the 15-20 knot range.
Aviation: VFR conditions will occasionally drop MVFR or possibly
IFR as cloud move through later today with lower ceilings and weather
that may wet the runway. Moderate to strong winds 16-22 knots from
230-250 degrees will diminish 10-15 knots later and then possibly
variable during the night. For more information, please visit www.weather.bm/aviation
Short Term Forecast: Wednesday – Thursday
On Wednesday as the upper trough further descends into the area,
zonal flow swings into cyclonic flow aloft with BDA on the front
side of the upper trough but as the trough moves out to the east
Bermuda then moves to the backside of the trough by Thursday afternoon.
At the surface, as a frontal boundary sinks into the area, fragmentation
occurs along the boundary as it drifts overhead which may allow a
few settled gaps interspersed with cloudy conditions and showers.
As the boundary lingers, a low to the west is dragged through the
area into early Thursday. GFS and ECMWF QPFs hint at near 1.25” of
accumulated rainfall expected on Wednesday while the UK model solution
is just above 0.5”, either way Wednesday sees a bit of rainfall.
As the boundary slips out to the southeast, high pressure builds
in from the west bringing settled weather into the area though a
few showers may linger. With a northerly flow, cooler and drier air
is pushed into the area allowing temperatures to drop near average.
With the favorable upper support, influx of moisture, and development
of the low on our doorstep, the potential for thunderstorm development
increases to a moderate level, especially on Wednesday. Wind data
within the model suite differs quite a bit with a 15-20 knot difference
between the GFS and the UK and EC. Both European models are hinting
at a southwesterly wind 20-30 knots while the GFS has winds light
to moderate at 6-12 knots. Seas remain moderate during the short
term.
Warnings: No watches or warnings are currently expected, though
if the UK/EC models are right then a Small Craft Warning may be needed
on Wednesday. A Thunderstorm Advisory may become warranted on Wednesday.
Long Term Forecast: Friday – Saturday
On Friday as surface ridging takes hold, an early shower or two
is possible as moisture moves around the edges of the high. On Saturday
things remain quite bright and sunny. Light to moderate near northerly
winds veer to the east then to the south by Saturday. Winds then
ramp up overnight on Saturday into the moderate to strong range which
would trigger the issuance of a small craft warning. Upper level
ridging amplifies on Friday into Saturday which will provide suppression
from aloft. Temperatures slightly warm going into Saturday with a
maximum in the low 70s F. Seas are expected to remain in a moderate
state during the long term forecast period.
WARNINGS: A Small Craft Warning may be required Saturday night for
strong winds. No other watches or warning are currently anticipated
during the long term period.