Area Forecast Discussion
Issued by NWS Boston, MA

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185 FXUS61 KBOX 262300 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 700 PM EDT THU MAY 26 2016 .SYNOPSIS... Warm weather will continue through Saturday, except at times along the immediate coast. A backdoor cold front will bring cooler weather to eastern MA Sunday with warm weather continuing elsewhere. Dry weather dominates through Sunday other than isolated showers/thunderstorms at times, then a period of more widespread showers are possible Monday. Above normal temperatures continue through midweek then turning cooler toward the end of the week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... 7 pm update... A few showers developed along the sea breeze boundary from southern NH into northeast MA but this activity is diminishing. HRRR is indicating a few showers tonight across northern MA as weak shortwave moves through. Current forecast on track. Previous Discussion... Mid level ridge sinks south a bit but overall conditions remain the same as previous couple of days. Winds will keep an onshore direction overnight so with sea surface temperatures in the mid to upper 50s, expect low temperatures in the same range along the coast. Temperatures will be warmer farther inland, with lows in the low 60s expected. A very weak shortwave will move through the westerly mid-level flow. This could result in a few showers occurring during the night. Think this will be very spotty and while there is enough instability for thunder to be possible, don`t think it will be frequent or common. Continued slight chance to very low end chance pops mainly for the western zones. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Friday...Mid level ridge continues to be the main influence of our weather. It will be another warm day for much of the area with southerly winds. The pressure gradient is a little tighter, so we may get away without a sea breeze developing on the east coast. The south coast will be the larger concern with southerly winds keeping temperatures along the coast cool. Expect high temperatures into the mid to upper 80s for most locations away from the south coast. A pre-frontal trough will move into southern New England during the day which could result in some convection. However, there are some limiting factors, including rising heights, that will limit this potential somewhat. There will be enough instability generated during the day as well as elevated instability for thunder to develop. Again, think this will be rather spotty and isolated for the most part. Friday night...Any isolated convection that does occur will diminish during the evening hours. Then dry weather is expected. Low temperatures are expected to be in the 60s. With dewpoints in the upper 50s to lower 60s, patchy ground fog will likely develop in the typically prone locations. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Highlights... * Hot Sat w/highs mainly 90-95 in the interior, cooler coast * Cooler Sun east coastal MA but continued very warm further in the interior * Mainly dry Sat/Sun other than iso showers/t-storms in the interior * More widespread showers may affect the region Mon then mainly dry for the rest of the week * Above normal temperatures through midweek then turning cooler Details... Saturday... Hot and increasingly humid conditions as anomalous mid level ridge builds across New Eng. 850 temps up to 17C will result in highs 90- 95 degrees in the interior, mainly west of I-95 corridor. SW flow off cooler SST will yield cooler temps in the SE coastal plain and especially along the south coast as mixing is more shallow and cooler 925 mb temps noted. Expect highs in the 80s coastal plain with 70s along the immediate south coast and Cape/Islands. The hot temps and increasing dewpoints will destabilize the atmosphere with CAPEs 1000-2000 J/kg developing in the interior. However, there are limiting factors with building mid level ridge and anticyclonic flow which will serve to suppress activity in the absence of notable synoptic forcing. And mid levels will be fairly dry. Most of SNE should remain dry but can`t rule out a few showers/t-storms across northern and western MA into western CT late in the day into Sat evening. Severe threat is low given weakly sheared environment, but if any convection develops there is potential for gusty winds with decent instability and inverted V sounding profile. Sunday... Timing of a backdoor cold front remains very uncertain which will significantly impact temps. GFS is most aggressive moving the front through much of SNE by morning while NAM/ECMWF are much slower and keep much of the region in the very warm air. Will continue the theme of the previous forecast indicating cooler air moving into eastern MA with temps mostly in the 70s, but warmer 80s further west and especially CT Valley where temps may approach 90 again if front is delayed. This is not a high confidence temp forecast as a 6 hour change in timing will make a big difference. Models generating 1000-2000 J/kg of SBCAPE west of the boundary so a few showers/t-storms possible ahead of the front, mainly central/W New Eng but this will be dependent on the timing and location of the front. Deep layer shear remains weak so severe threat is low. Monday... Models indicate a mid level shortwave moving through as a plume of tropical moisture surges northward ahead of possible tropical disturbance to the south. Models indicate PWATs increasing to near 2 inches with marginal instability developing, depending on extent of cloud cover. This may lead to more widespread showers and sct t- storms with locally heavy rainfall possible. Confidence on how this plays out is not high but the potential exists for wet weather. Temps will be dependent on extent of clouds/showers but a cooler day is likely. Tuesday through Thursday... Deep moisture plume will be exiting the region by Tue as a cold front moves offshore with significant decrease in PWATs. Looks mainly dry Tue although if front is slower, shower threat could linger. Then mainly dry Wed/Thu as high pres builds in from the N. Temps cooling mid to late week as easterly flow develops. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight...High confidence. VFR conditions likely for much of the period. Low probability of brief MVFR conditions in SCT -SHRA/-TSRA mainly across W MA/N CT. Friday...High confidence. Mainly VFR. Low probability of brief MVFR conditions in SCT -SHRA/-TSRA mainly across the interior. Friday night...High confidence. Mainly VFR. Patchy ground fog develops resulting in patchy MVFR/IFR conditions. KBOS TAF...High confidence in TAF. KBDL TAF...High confidence in TAF. Outlook /Saturday through Tuesday/... Saturday...High confidence. Mainly VFR other than a few hours of patchy ground fog toward daybreak Sat in the typically prone locations. Isolated late day/evening showers/t-storms possible distant interior. Sunday...Moderate confidence. Mostly VFR but patchy MVFR cigs possible eastern MA depending on location of backdoor front. Widely scattered showers/t-storms possible interior. Monday...Low confidence. Potential for a period of MVFR-IFR conditions in low clouds and showers/t-storms. Tuesday...Moderate confidence. Mainly VFR, but lower conditions possible in the morning especially near the coast. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Friday Night/...High confidence. High confidence. Quiet boating weather is expected through the short term. There is a low probability of seas reaching 5 feet on the outer waters Friday night. Winds will generally be out of the south. Fog may develop over the waters Friday night, limiting visibilities. Outlook /Saturday through Tuesday/...High confidence. Winds and seas will generally remain below small craft advisory thresholds through the period, but there may be a period of SW gusts approaching 25 kt on Monday over nearshore waters. && .CLIMATE... Warmest day of the week appears to be Saturday and some record highs may be challenged. Record highs for Saturday May 28... Boston...92 set in 1931 Providence...91 set in 1931 Hartford...93 set in 1977 Worcester...88 set in 1911 and 1929 Milton/Blue Hill...90 set in 1929 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Air Quality Alert until 11 PM EDT this evening for CTZ002>004. Air Quality Alert from 11 AM to 11 PM EDT Friday for CTZ002>004. MA...Air Quality Alert until 11 PM EDT this evening for MAZ002>005- 008>014-017-018-020-021-023-026. RI...Air Quality Alert until 11 PM EDT this evening for RIZ001>008. MARINE...None. && $$ SYNOPSIS...KJC/RLG NEAR TERM...KJC/RLG SHORT TERM...RLG LONG TERM...KJC AVIATION...KJC/RLG MARINE...KJC/RLG CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.