Bermuda Weather Service Forecast Discussion

For Friday, December 09, 2022  10:00 UTC

FORECASTER - Alex Young 

NOWCAST: (Today and tonight)
The night was mostly cloudy and dry initially and became overcast 
with showers, rain and low ceilings after 08Z/04L as a cold front 
passed over the island. Latest satellite imagery shows cloudy to 
overcast skies slowly exiting to south and east while partly cloudy 
to cloudy skies is seen upstream on the area. Latest radar imagery 
shows scattered to widespread showers exiting the marine area while 
isolated showers and patchy rain linger behind the front. An upper 
ridge southeast of the subtropical jet remains over the region as 
upper troughing is seen east of northeastern CONUS as evident on 
WV imagery. Latest surface analysis shows a 971mb broad area of low 
pressure now to the distant east-northeast, a cold front just west 
of the island connected to two low centres to the north-northeast 
and high pressure over northeastern and southeastern CONUS. This 
has initialized really well with global models and there is high 
confidence in the synoptic set up for today. Global models are in 
good agreement that the upper trough to our northwest will continue 
to dig southwards towards the area bringing weak cyclonic flow. A 
cutoff upper-low forms by this afternoon would aid the rapid development 
of a surface low to the north. In addition, global models agree that 
the cold front will soon clear the island and marine area with lingering 
showers and rain soon clearing by mid-morning with brighter skies 
returning for a brief time. Cloud cover then increases towards the 
evening as a developing low to the north, sends a series of troughs 
through the area with blustery showers. The high for the day was 
likely reached overnight and cooler temperatures are expected today 
into tonight in the wake of the front. Winds overnight at the airport 
and our AWOS, steadily increased from 10-15 knots to 12-18 knots 
and then 16-22 knots whilst gradually veering northerly from west-northwesterly. 
As the front passed, gustier winds were observed with a peak wind 
of 31 knots and a peak gust of 40 knots recorded at the Crescent 
with similar values observed at NMB.  Currently, winds have settled 
near northerly around 16-22 knots and have initialized well with 
the global models giving high confidence. Expect winds to continue 
to gradually increase through the day to 20-25 knots and then 20-30 
knots overnight whilst backing northwesterly. Latest OPC has seas 
near 10-12ft which is in agreement with model initialization. Seas 
are forecast to remain rough to very rough

Warning Strategy: A small craft warning is in effect for this morning 
through tonight.

AVIATION: Runway 30 will likely be the active runway for the day 
as a near northerly wind backs northwesterly. Winds 16-22 knots will 
increase 20-25 knots towards the afternoon and then 20-30 knots overnight 
which will prompt the issuance of multiple Airfield Warnings for 
Strong Winds and Gusts. There is also the potential that Wind Shear 
Warnings may be needed as well.  Early MVFR to possibly IFR conditions 
will give way to VFR conditions and would occasionally become MVFR 
overnight as blustery showers move through the area which may result 
in a wet runway. No other aviation hazards are anticipated. For more 
information visit: http://weather.bm/aviation/


SHORT TERM FORECAST (Saturday through Sunday)
Upper cyclonic flow becomes more pronounced on Saturday and will 
provide upper-level enhancement for a developing low pressure system. 
Upper ridging then gradually builds into the area on Sunday with 
weak anticyclonic flow. At the surface, another low will steer occasional 
passing showers through the area as a broad trough associated with 
the low passes between Saturday afternoon and Saturday night. The 
low begins to exit the area on Sunday, though trailing troughs and 
bands of convergence will likely bring additional blustery showers 
on Sunday though a drier trend begins from Sunday. Wind data remains 
in fairly good alignment and suggest windy conditions on Saturday 
with northwesterly winds of 20-30 knots increasing 30-35 knots from 
early Saturday morning to Saturday evening with gusts to 40-45 knots 
as per boundary layer winds. Winds then ease moderate to strong overnight 
and continue to ease through Sunday, becoming light to moderate by 
Sunday night. QPFs do not look overly impressive ranging between 
0.1-0.5 of rainfall over both days. Cooler temperatures return post 
fropa on Friday with MOS suggesting lows near 62F and highs in the 
upper 60s F. Rough to very rough seas build high through the short-term 
period with a peak near 16-20ft forecast on the latest model run.

Warning Strategy: A small craft warning Is in effect until Saturday 
morning and then again from Saturday night through Sunday night. 
A gale warning has been issued for Saturday morning to Saturday evening.

LONG TERM FORECAST (Monday through Tuesday)
Anticyclonic flow becomes more pronounced on Monday along the upper 
ridge and then gradually weakens on Tuesday. At the surface, transient 
high pressure brings sunnier skies expected during the day on Monday, 
before yet another low and front approaches Monday night with developing 
showers. The front clears early Tuesday with weak flow settling over 
the area in its wake. Light to moderate winds early on Monday increases 
moderate to strong once more on Monday night through Tuesday whilst 
varying (veering and then backing) between west-southwesterly and 
northerly. Rough to very rough seas persist through the long-term 
period as well.

Warning Strategy: The small craft warning will likely be extended 
through both Monday and Tuesday.