Bermuda Weather Service Forecast Discussion

For Tuesday, June 25, 2019  21:00 UTC

FORECASTER - Eric Drewitz 

NOWCAST (Tuesday evening-Tuesday night):
Current GOES16 VIS imagery shows cloud associated with a weak trough 
approaching from the west. Due to this I expect mostly cloudy skies 
tonight with isolated showers in the W’rn marine area. Observations 
showed more cloud than sun today with having a BKN layer during the 
majority of the afternoon. Observations show SW’ly winds at 8-12kts 
which is in slightly better agreement with the UKMO than GFS. Winds 
are expected to back S’ly overnight. OPC analysis shows 2-3’ seas 
which is consistent with the UKMO wave model. Seas will remain 2-3’ 
tonight. No watches, warnings or advisories are in effect or are 
expected at this time. I have a high confidence in the nowcast portion 
of the forecast period. 

AVIATION: VFR conditions are expected as ceilings will remain above 
3000’ AGL and visibility unrestricted. 

SHORT TERM FORECAST (Wednesday-Thursday):
Guidance has now shifted towards the ECMWF solution in the past 
24 hours, hence now I am expecting more cloud and showers compared 
to yesterday’s model runs. Due to this latest trend between guidance 
I have now weighted the ECMWF and UKMO more than the GFS. ECMWF is 
the most “pessimistic” solution while the GFS is the most “optimistic” 
and the UKMO is in between. GFS keeps Bermuda under high pressure 
ridging, allowing Bermuda to remain sunny and dry. UKMO shows a weak 
slow moving trough stalling over the area, bringing cloud and showers 
which is consistent with the ECMWF, except the ECMWF shows a broader 
trough than the UKMO. Due to this I am expecting periods of hazy 
sunshine with a shower or two possible. Stability indices are not 
in favor of thunderstorm development as there are only marginal 30-35 
K-Index values with nothing else to support thunderstorm development. 
Winds will also remain at 10-15kts as this will be a weak trough, 
thus no strong pressure gradients between the trough and the Bermuda-Azores 
high to the east. UKMO wave model suggests seas to abate from 2-3’ 
on Wednesday to 1-3’ on Thursday. No watches, warnings or advisories 
are expected at this time. Due to the recent inconsistencies between 
models with weak pressure gradients being expected, I am only moderately 
confident at best in the forecast as models have a harder time at 
resolving weather patterns with weak pressure gradients. 

LONG TERM FORECAST (Friday-Saturday):
Guidance shows a cold front moving through the region during this 
time period, though major inconsistencies exist on the timing of 
this front as it will be a weak front with no significant pressure 
gradients. UKMO has the front move through the earliest around 06z 
on Friday while the ECMWF leans more toward 12z Friday and GFS not 
until 03z Saturday. My confidence is very low at the moment, though 
I weighted the UKMO and ECMWF more in my wind forecast as these models 
are more consistent with timing while the GFS appears to be the major 
outlier. The one consistency is less cloud on Saturday as a second 
ridge builds in behind the front which is shown in all models. No 
watches, warnings or advisories are expected during this time. 

TROPICAL OUTLOOK: 
Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Tue Jun 25 2019

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Tropical cyclone formation is not expected during the next 5 days.