Bermuda Weather Service Forecast Discussion

For Tuesday, January 23, 2018  20:00 UTC

FORECASTER - Jennifer Smith 

NOWCAST (Tonight) 
Surface high pressure situated E of Bermuda extends a ridge westward 
to encompass the Island. Satellite imagery and local observations 
indicate fair weather cumulus clouds and some wisps of cirrus which 
will make for a relatively clear night. Temperatures continue to 
be slightly above seasonal with a moderate breeze from the S. Seas 
are presently analysed around 3’ according to OPC analysis and surrounding 
buoys and with a very slight increasing trend through the night.

Aviation: VFR…no hazards

SHORT TERM FORECAST (Wednesday & Thursday)
Surface high pressure continues to shield Bermuda through much of 
Wednesday although cirrus will overspread to dim the sun, and gradually 
lower clouds will move from the W to cover the sky by evening.  South-southwesterly 
winds ramp up in speed and flirt with the 20 knots mark as a cold 
front slowly approaches. Overall a warm, fairly sunny day is in store 
as most of the cloud cover moves in toward sunset. The energy associated 
with this system remains well to the N with a cold front dragging 
along and fragmenting as it tracks E. Expect a few showers starting 
late Wednesday due to convection popping up ahead of the main frontal 
boundary, which is progged to pass over the Island with more organized 
shower activity during the day Thursday.  The GFS continues to run 
about 3-6 hours quicker with the front than the UKMO, but overall 
decent agreement on showers developing and maybe the off-chance for 
a clap of thunder.  CAPE and all other indices continue to be borderline 
with regard to deep convection but the forecast soundings remain 
modestly unstable/saturated and suggestive of a couple of thunderstorms 
developing along the front. No mention in the forecast for now, but 
if the environment turns more favourable, it may be introduced.  
Temperatures are likely to remain steady through the morning with 
a cooling trend going forward as winds shift W and later NW behind 
the front. Strong NW flow on the order of 25 knots will advect a 
markedly cooler airmass into the region overnight into Friday, plummeting 
850mb temps to around 0C. A small craft warning is valid for Wednesday 
and much of Thursday for winds, followed by seas rising to the 9’ 
mark later on Thursday. 

LONG TERM FORECAST (Friday & Saturday)
As high pressure begins nosing in from the W and the exiting cold 
front & parent slow stalls to the E, a tight NW gradient will continue 
to produce strong winds over Bermuda. Typical wintertime stratocumulus 
cloud cover will set up post front with a chance for a couple of 
very light showers to be around Friday. That, combined with the windy 
condition will make for a noticeably cool start to the day. 850mb 
temps hover in the low single digits which will both maintain a shallow 
unstable environment and keep surface temperatures from climbing 
much above 60-62F. This cool regime continues into the weekend but 
with gradually more breaks of sun and declining winds as high pressure 
builds from the W. Seas build moderate Thursday and later become 
rough on Friday in response to the stronger winds. Both winds and 
seas will warrant a small craft warning through Friday, and then 
for seas through Saturday as they slowly fall.