Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Juan PR
1056 PM AST Wednesday Apr 1 2015
Update...satellite images are indicating that an area of
cloudiness with shower activity is moving towards the forecast
area across the Leeward Islands. Therefore...scattered showers are
expected across the usvi's and the eastern half of Puerto Rico
during the overnight and early morning hours. At least for the
next few days a wetter pattern is expected across the forecast
area. Cloudiness with periods of showers and thunderstorms are on
tap at least through Saturday. No changes made to previous forecast
Aviation...VFR conditions tonight through middle-morning Thursday.
T-storms possible Thursday especially at jbq and jmz. Inclement weather
possible Friday and especially Sat at eastern PR...USVI and Leeward
Marine...no changes made to previous discussion.
Previous discussion... /issued 257 PM AST Wednesday Apr 1 2015/
Synopsis...a series of middle-upper level disturbances will move
across the area Thursday through Saturday. Ridge of high pressure
will build over the region early next week.
Discussion...active weather appears on tap Thursday through Sat as height
falls in response to a series of middle-upper level disturbances
moving across the area. First disturbance will move across the
area Thursday with heavy showers and T-storms over western PR. Possible lull
in activity Friday however middle-level dry air intrusion and cold
advection aloft could result in some strong T-storms over SW PR.
A second fairly strong disturbance will be deepening as it crosses
the area and provide large scale forcing for upward vertical
motion. Best moisture is over eastern PR with steering motion
toward the southeast. 500 mb temperatures cool down to -11c with
potential for hail. Flooding not likely due to very dry antecedent
conditions but severe weather not out of the question Friday and
especially Sat. Conditions begin to improve on Sunday under
Marine...winds 15 knots and seas 3-5 feet through Thursday. Winds and seas
build on Friday. T-storms likely Thu-Sat.
Preliminary point temps/pops...
sju 75 85 75 85 / 40 40 30 20
stt 75 83 74 82 / 40 40 20 10