Area Forecast Discussion
Issued by NWS San Juan, PR
Issued by NWS San Juan, PR
726 FXCA62 TJSJ 202015 AFDSJU Area Forecast Discussion National Weather Service San Juan PR 415 PM AST Thu Jun 20 2024 .SYNOPSIS... Passing showers dragged by the trade winds will continue to move into the islands during the overnight hours. For the next few days, a very typical weather pattern will establish with active afternoon convection over the interior and western Puerto Rico. A series of tropical waves will approach the area starting early next week. && .SHORT TERM...Tonight through Saturday... Variable weather conditions prevailed today throughout the region. An increase in the trade winds resulted in fast moving showers during the morning hours, leaving minor accumulations across the area. Today, remarks the beginning of the astronomical summer and with that a very typical weather pattern prevailed over the islands. Easterly winds in combination with daytime heating and local effects resulted in afternoon convective activity over western Puerto Rico. Moderate to heavy showers and isolated thunderstorms affected portions from Adjuntas to Mayaguez, leaving accumulations of up to 2.0 inches over Hormigueros. In terms of heat, daytime temperatures remained in the range between the upper 80s to lower 90s along the coastal and urban sectors, and in the low to mid 80s in the mountains. Heat indices were observed in the mid 100s mainly over the coastal and urban sectors. A broad surface high pressure in the central Atlantic will continue to promote moderate to locally fresh winds through the rest of the short-term period. Patches of moisture will continue to approach the area, promoting shower and thunderstorm activity during the afternoon hours mainly over the interior to western Puerto Rico and downwind of the local islands. By the weekend, low concentrations of Saharan dust particles could reach the local area as drier air filters in. The next tropical wave is expected to reach the islands by early next week. Overall, at 925 mb warm temperatures will continue to persist with heat indices over the mid 100 degrees Fahrenheit. Therefore, the risk for excessive heat will stay from limited to elevated for the next several days. .LONG TERM...Sunday through Thursday... ./FROM PREV DISCUSSION...Issued at 420 AM AST Thu Jun 20 2024/ A surface high stretched across the central Atlantic will bring a pattern of trade wind showers followed by afternoon convection across the islands on Sunday into the early of next week. Plenty of moisture remains over the area with consistent high precipitable water values which will yield in an abundance of showers at times. By Tuesday, a tropical wave begins to move across the area, bringing unstable conditions across the the lower levels and continuing the trend of moist conditions. Generally relatively high pressure will remain across the mid to upper-levels during this time, however with the instability caused by the tropical wave and a continued east to southeasterly flow, rain may be persistent and heavy a few time throughout this period. Afternoon convection due to local effects and diurnal heating will play a big role in allowing thunderstorms to form, with western Puerto Rico most likely to receive the bulk of rain and the greatest risk of excessive rainfall. && .AVIATION... Mainly VFR conditions are expected to prevail across all terminals during the next 24 hours. However, trade wind SHRA en route fm the Leeward Islands will move at times across the USVI and eastern PR terminals through the overnight. Afternoon convection is expected once again aft 21/16z across western PR, which may cause VCTS at TJBQ/TJPS. VCSH expected across the rest of the terminals thru most of the fcst period. East winds at 15-25 kt will continue blo FL160. && .MARINE... A surface high pressure over the central Atlantic will promote moderate to locally fresh easterly winds through the rest of the week. Trade wind showers will move across the regional waters from time to time. The next tropical wave will approach the local islands by the beginning of the next workweek. && .BEACH FORECAST... A moderate risk of rip currents is in effect for the northern, eastern and southwestern exposed beaches of Puerto Rico, Vieques, Culebra and St. Croix. Remember, life-threatening rip currents are possible in the surf zone. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. && $$ SHORT TERM...CAM LONG TERM....GRS AVIATION...DSR PUBLIC DESK...MRR