Bermuda Weather Service Forecast Discussion

For Tuesday, August 09, 2022  21:00 UTC

FORECASTER - Anton Wiltshire 

Forecast Discussion
Tuesday August 09th, 2022, 21UTC
Forecaster – Anton Wiltshire 

Nowcast: Tonight
Today was predominantly bright and sunny despite clusters of thunderstorms 
associated with an area of convergence remaining to the distant NW-N 
and continuing to move in a NE’ly direction.  At the surface, ridging 
is the dominant feature in the area and is skewed NE to SW with the 
ridge axis passing south of the island. The orientation of the high 
has brought light SE’ly winds over the area becoming variable at 
times and is expected to veer SSW’ly overnight. Upper level lows 
to the SE and NE are expected to merge and become an elongated trough 
which has started to erode the upper ridge producing cyclonic flow 
aloft.  As the day progressed, the latest satellite imagery shows 
some island streamers to the NNE, small patches of fair weather cumulus 
and clusters of thunderstorms to the distant NW-N, some pushing into 
the marine area.  RADAR imagery shows mainly weak to isolated moderate 
echoes within the marine area and stronger echoes to the NW-N. Few 
lightning strikes recorded by AWOS to the west between 19-55km away. 
Tonight models forecast the convergence band to come closer to the 
island but remaining in the marine area and not affecting the island 
too much. OPC currently has 2-3 ft seas for the area and this has 
initialized well with global models.     No watches or warning expected 
for the nowcast period

Aviation: VFR conditions continue tonight with mainly light and 
variable winds up to 8 knots, generally from the SSW with no aviation 
hazards expected for the period. For more information please see 
Short-Term: (Wednesday – Thursday)
The short-term weather will be characterized by settled weather 
with plenty of sunshine.  As the surface ridge stick around, winds 
at the surface are expected to be light and variable at times with 
speeds up 9 knots.  It is possible that winds may even drop to calm 
overnight.   On Thursday the surface ridge breaks down slightly and 
a weak perturbations to the north brushes the area with minimal moisture, 
hence a shower or two cannot be ruled out.  With weak winds and plenty 
of daytime heating, provided a steady direction can be maintained, 
the development of homegrown cloud/island streamers is possible. 
  This will have to be a nowcast situation though. By Wednesday, 
that elongated upper trough shift S and the ridge can shift southward 
and regain its hold over the area.  Global models keep temperatures 
quite warm in the short term with highs between 85-87F and lows of 
79-80F.  Model data keeps sea states smooth to slight.  No watches 
or warning are anticipated for the short term forecast.

Long term: Friday through Saturday
On Friday the wind regime changes where the wind speeds increase 
up to 12 knots from the SSW-SW.  During Friday, as the surface ridge 
is eroded a bit, an inverted trough makes its way into the area and 
a frontal boundary to the northwest.  The UKMO has quite a bit more 
moisture and heavier showers over the area associated with the frontal 
boundary to the northwest compared to the GFS, that is keeping the 
bulk of the weather further away. Both models are not in agreement 
with an inverted trough moving south of the area as the UKMO has 
it moving west on Friday but the boundary to the NW having a greater 
influence on local weather.  The GFS has a more ridging flow with 
S’ly-SSW’ly flow.   Depending on which model used, there is the possibility 
for increased moisture and cloudiness later Friday into Saturday 
with light to moderate winds.  Seas expected to remain smooth to 
slight for the long term period.  No watches or warning are anticipated 
for the short term forecast.

TROPICAL:  Please refer to the latest Tropical Weather Outlook (TWO) 

courtesy of the National Hurricane Center (NHC) for more details