Bermuda Weather Service Forecast Discussion

For Wednesday, July 17, 2019  20:00 UTC

FORECASTER - Andrew Bufalino 

NOWCAST (Wednesday)
GOES-16 satellite imagery in conjunction with ASCAT shows that the 
front to our north, which has recently been quasi-stationary for 
the past 3-5 days, has started to retreat northeast. In addition, 
the prefrontal trough that's responsible for the majority of showers 
reaching Bermudian latitudes has also shifted north, however only 
slightly. This has caused a reduction in showers across the forecast 
area with the focal point for deep convection being well north of 
the island. ASCAT 01-03UTC did indicate a small-scale circulation 
to our north, resulting in a bulging ridge over Bermuda. This is 
most likely the reason why showers never really became active and 
extensive today, or even last night. Observations show that winds 
are currently between 250-270 degrees, notably inconsistent from 
all global models. Since winds have varied from the expected 240 
degrees, Morganís Cloud is now not expected to develop for the remainder 
of today. 

AVIATION: A recent amendment was transmitted to exclude potential 
TEMPO conditions for TXKF. This was largely due to the lack of Morganís 
Cloud, wind regime and development upstream. Although itís below 
30%, SHRA with 3200 visibility and BKN014 ceilings cannot be ruled 
out overnight and into Thursday morning. While dew points remain 
high, low ceilings are once again not expected, however scattered, 
low cloud cover may develop at times.

SHORT TERM (Thursday and Friday)
Upper level ridging will strengthen over Bermuda on Thursday, reaching 
heights  around 594gpm during the day. The centre will initially 
be located over the forecast area, however overnight Thursday and 
into Friday, the centre will retrograde west and continue to promote 
broad-scale subsidence. On the surface, the stationary front that 
has been toying with our local weather conditions will begin to weaken 
and shift further northeast, subsequently diminishing our only source 
of synoptic lift. In wake of this system, surface ridging will continue 
to move in from the south, further stabilizing the atmosphere. Expect 
light to moderate southwesterly winds, tending south-southwesterly 
at times. Due to lingering instability with sufficient low-level 
moisture, an odd shower or two remains possible across the area. 
Seas are expected to continue in the 2-3í range. No watches, warnings 
or advisories are expected during the short term forecast time frame. 
 

LONG TERM (Saturday and Sunday)
Upper level ridging will remain in place across Bermudian latitudes 
during the outlook period. Due to an upper trough rotating east across 
the northwest Atlantic, the upper ridge does temporarily weaken in 
response. However, mid-level temperatures do not alter and cool, 
therefore it will not support parcel ascent. The surface ridge will 
be located in close proximity to Bermuda, perhaps to our direct south. 
Lingering elevated moisture content in combination with instability 
will continue to provide the potential for some isolated shower activity, 
though the nearby ridge will contain the majority of convection. 
Morganís Cloud seems possible however the strength of the southwesterly 
regime may be too light. No watches, warnings or advisories are expected 
during the long term forecast time frame.


TROPICAL WEATHER OUTLOOK
NWS National Hurricane Center Miami FL
200 PM EDT Wed Jul 17 2019

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:
The Weather Prediction Center is issuing advisories on Post-Tropical 
Cyclone Barry, located over Ohio.
Tropical cyclone formation is not expected during the next 5 days.