Bermuda Weather Service Forecast Discussion

For Saturday, April 21, 2018  07:00 UTC

FORECASTER - Michelle Pitcher 

FORECAST DISCUSSION	Michelle Pitcher	Saturday, April 21, 2018
NOWCAST (Saturday)
Surface high pressure builds from the west today with cooler temperatures 
and lower humidity.  Winds gradually decrease from 12-18 knots this 
morning to 8-12 knots towards evening.  Models indicate that the 
current cloud cover will thin during the day, providing long sunny 
periods to partly cloudy skies at times.  There is some evidence 
of this in the latest infra-red satellite imagery as it shows the 
edge of the thicker clouds moving closer to Bermuda.  Skies are expected 
to remain partly cloudy tonight as the high continues to strengthen. 
 The latest NOAA OPC Wind/Wave analysis has seas about 6 in our 
area.  Wave models indicate that seas will diminish today, becoming 
closer to 4-5 tonight.  Models have initialized well as they are 
in excellent agreement with current conditions as well as each other. 
 No watches or warnings are valid at this time.
AVIATION:  VFR conditions are expected today as winds generally 
remain 360 degrees and decrease slightly from 12-15 knots to 8-10 
knots by evening.
SHORT TERM (Sunday & Monday)
Upper level flow remains zonal through Sunday and then becomes cyclonically 
curved Monday morning.  A trough axis is expected to pass over the 
area Monday evening.  Upper ridging then begins to amplify over the 
area late Monday night.   The surface ridge slowly retreats to the 
west during the day Sunday.  More sun than cloud is expected as the 
cool dry air continues to dominate the area.  Winds veer from the 
north to the northeast later on Sunday and continue to remain 8-12 
knots; at times lighter.  The ridge remains fairly steady over the 
area on Monday as the high center begins to move to the distant north. 
 Winds increase to 12-18 knots on Monday as a low pressure system 
traveling north along the southern US East Coast creates a pressure 
squeeze.  The distant warm front also increases clouds in the area 
and there may be a couple of morning showers due to moisture flowing 
around the high.  Wave models decrease seas to 4 Sunday afternoon 
and then seas remain 2-4 through Monday.  Temperatures remain on 
the cool side for both days and lower humidity is expected.  Models 
are in good agreement on conditions for both days.  No watches or 
warnings are anticipated for these days at this time. 
LONG TERM (Tuesday & Wednesday)
Upper ridging continues to amplify over the area on Tuesday and 
the upper ridge axis is expected to pass early Wednesday morning. 
 A broad upper trough will then drift slightly east, off the southern 
US East Coast, and then the upper level flow changes late Wednesday 
night into Thursday.  The center of the surface high slowly moves 
northeasterly during these days as the low pressure center to the 
west continues to crawl up the US East Coast.  Winds increase to 
strong by Tuesday evening and remain mainly strong through Wednesday 
as they veer to the southeast.  Part of the warm front may enter 
the area later Wednesday night with the GFS bringing it in then and 
the UK holding off until later Thursday.  I have left Wednesday dry 
for now as the models have such very different timings.  Other than 
the precipitation, models are in fairly good agreement with each 
other on these conditions.  Wave models increase seas to 5 on Tuesday 
and 6 on Wednesday.  A small craft warning will be needed by Tuesday 
morning for the winds.  No other watches or warnings are anticipated 
for these days at this time.