Bermuda Weather Service Forecast Discussion

For Saturday, June 24, 2017  09:00 UTC

FORECASTER - Jennifer Smith 

NOWCAST (Today-Tonight) 
Satellite imagery shows several cloud layers across the region. 
While the 00z sounding indicated sufficient instability for elevated 
convection, Saturday sees a return to stable, dry weather with some 
sunny breaks as surface high pressure reasserts itself over our area 
and upper level ridging builds through the day. A weak inversion 
just above the boundary layer should also prevent any significant 
Morgan’s cloud development. Temperatures are above seasonal, peaking 
at around 29C/83-84F with overnight lows at 26C/77-78F. 

Marine:  Seas are presently analysed around 3-5’according to OPC 
analysis and surrounding buoy reports, which is slightly higher than 
what the latest model guidance is suggesting but as the low-levels 
of the atmosphere stabilize today, surface winds will weaken to be 
in line with forecast model guidance. Seas will are expected to fall 
slightly in the response to the winds.

Aviation: few-to-scattered MVFR cloud with brief ceilings possible 
and several cloud layers above 10000 ft overspreading through the 
day.  Winds will be 230-260 deg near 10kt.  Winds favour Morgan’s 
cloud development but stable conditions should prevent significant 
vertical growth in clouds.

Through Sunday, surface ridging holds strong across the Bermuda 
area lending to a fine day. Monday, the ridge gradually erodes away 
to the east and is slowly replaced by a deepening long wave upper 
trough. Winds are generally light but pick up a southerly component 
drawing low-level moisture into the region and increasing low cloud 
development for Monday. As another frontal wave emerges from the 
US coast, supported by the aforementioned broad long-wave trough 
that sharpens and deepens over eastern North America, spotty showers 
will begin to develop across the region in the convergent surface 
flow ahead.  While the front itself holds to the northwest throughout 
the forecast period cloud cover will trend up and showers are likely 
later on Monday. Seas maintain slight as light to moderate winds 
back from southwesterly to southerly over the course of the two days.

LONG TERM FORECAST (Tuesday-Wednesday)
Tuesday and Wednesday Bermuda is under the influence of a deep upper 
level trough. Isolated showers are likely to become scattered over 
the course of Tuesday in the continued low-level convergence between 
the ridge southwest of Bermuda and the front dragging in from the 
northwest. Southwest winds also strengthen to low-end moderate as 
the gradient tightens. Overnight and through mid-afternoon Wednesday 
the active front brings scattered to widespread showers to the region 
with a chance for heavy showers and/or thunder as it passes. Expect 
southerly winds to rapidly shift to be from the north with the frontal 
passage, presently progged for mid-afternoon Wednesday. Both the 
GFS and UK solutions have indicated an uptick in shower potential 
for Tuesday and organized showers through much of Wednesday, with 
the UK being more aggressive both days. The forecast reflects the 
trend but recognizes the wetter solution remains the outlier at this 
time. Post front, showers taper and a clearing trend is anticipated 
under north/northeasterly flow. Seas will become slight to moderate 
in response to the stronger winds both days, and a sharp winds shift 
is expected mid-afternoon Wednesday.

The National Hurricane Center in Miami, FL is issuing advisories 
on Post-Tropical Cyclone Cindy, located over the central Appalachian 
Mountains in the USA, and will be no threat to Bermuda as it further 
decays. No new tropical cyclone formation is expected during the 
next 5 days.