Bermuda Weather Service Forecast Discussion

For Saturday, February 24, 2018  10:00 UTC

FORECASTER - Levi Blanchette 

NOWCAST (Today)
Upper ridging from the west slowly retreats while weakening as an 
upper trough sinks S over the central Natl today. Meanwhile, the 
surface high remains centered to our west as a backdoor trough draws 
in from the NE. The latter could introduce some isolated light showers 
across the region, nut most likely just in the marine area. 12Z vertical 
sounding showed very dry air above a thin saturated layer around 
920hPa. Winds remain light and variable this morning, but settle 
NW’ly and increase a bit this afternoon. Satellite imagery has been 
showing patches of broken stratocumulus drifting S across the area 
among clearer spells. Some trace precipitation has affected us early 
this morning and produced by the latest model runs for tonight as 
well, suggesting skies remain on the cloudy side as the trough approaches 
from the NE with the aforementioned chance of precipitation. Expect 
a steady temperature trend but with humidity increasing overnight. 
The OPC analyzes Bermuda in a 2-3ft significant wave height, closely 
matching wave model guidance. Calm to smooth seas inside the reef 
and smooth to slight seas outside slowly increase to smooth to slight 
inside and moderate outside the reef come dawn mainly due to building 
swells. No watches, warnings or advisories are expected.

AVIATION (TXKF TAF) 
VFR conditions…Light and mainly variable winds become 330 deg around 
noon LT. FEW to SCT lower clouds overnight will burn off after sunrise 
and should not cause any low CIGS through the period. 

SHORT TERM FORECAST (Sunday-Monday)
The upper ridge continues slowly to erode through the period while 
remaining the dominant feature aloft, blocking the Jetstream well 
to the N and NE as a cut-off upper low forms in the central NAtl 
on Sunday. The filling trough on Saturday leaves room for the high 
to our W to broaden into the area while slowly weakening throughout 
the period, causing pressure to slowly but steadily fall. However, 
the high is still strong enough to block a trailing cold front to 
NE on Sunday and ensure mainly fair weather throughout the weekend. 
Skies significantly brighten up and prolonged sunny intervals develop 
Sunday and for much of Monday. Persistent light to moderate winds 
from the NW are expected throughout the period, beginning to increase 
moderate to near-strong late Monday while backing more W’ly, Seas 
remain slight to moderate, however small craft warning may need to 
be initialized as early as Monday night late due to winds nearing 
strong.

LONG TERM FORECAST (Tuesday-Wednesday)
Upper levels return more zonal for the period as an upper trough 
amplifies W over the NAtl. At the surface, high pressure gradually 
sinks S on Monday as a frontal trough is driven SE into the region 
Tuesday morning. Fair skies earlier on Monday gradually become more 
cloudy by evening and further overcast on Tuesday as a band of showers 
arrive from the NW, clearing during the afternoon with conditions 
drying up behind the front from the evening. Models have begun to 
come into alignment that the front should pass around noon on Tuesday. 
On Wednesday, veer NE’ly then E’ly and ease a bit. With the weaker 
NE’ly flow, it’s likely bands of StratoCU will persist through Wednesday, 
although models aren’t going for any precipitation. Good confidence 
that seas will quickly build to rough on Tuesday under the boost 
in the winds and remain rough through Wednesday due to increased 
northerly swell. A Small Craft warning will most likely be needed 
for this period due to winds on Tuesday, then seas through Wednesday.