BOX issues Area Forecast Discussion (AFD) at Jul 26, 6:40 AM EDT262
FXUS61 KBOX 261040
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
640 AM EDT Fri Jul 26 2024
.SYNOPSIS...
Dry and seasonably warm conditions with comfortable humidity levels
are expected today and Saturday with a slight uptick in humidity on
Sunday. The weather pattern then turns unsettled for much of next
week with chances of showers and perhaps a few thunderstorms, along
with increasing humidity.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
640 AM update...
Mid level trough and pocket of cooler air aloft will allow some
diurnal cu to develop by late morning, but otherwise a mostly
sunny day. Some gusty NW winds this morning, then slackening
gradient and developing weak surface trough will lead to
afternoon sea-breezes developing. Current forecast on track.
Previous discussion...
Surface ridge/high pressure begins to build in today though mid
level trough/cold pool remains centered over northern New England
today. As a result, we'll see much sunnier skies compared to the
last several days, but cold pool driven diurnal cumulus is likely to
form, particularly across the eastern half of the CWA, late this
morning and early this afternoon given 700mb temps around 3C. Drying
NW flow will continue to pump dry Canadian air into the region with
PWATs falling below an inch this afternoon (with dewpoints in the
50s), thus, think it will be too dry for any brief, light showers to
fall from developing cumulus field. While temps aloft are chilly,
especially by July standards, steep low level lapse rates will yield
high temps in the upper 70s and low/mid 80s across the region.
NW flow remains gusty this morning but will decrease from ~15-20kt
to ~5-10kt thanks to height rises as ridging builds in. As a result,
coastal areas are likely to experience a late day seabreeze (after
18/19Z).
The most interesting phenomenon of the day will be a hazy appearance
to the sky as northwest flow will advect smoke from the Western
US/Canadian wildfires over the region. At this time, smoke appears
to be elevated, posing no threat to air quality.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
Low/mid level ridging and high pressure continues to push into
southern New England tonight and Saturday, though residual mid level
weak troughing will lead to another afternoon of diurnal cumulus on
Saturday. With a weaker pressure gradient in place, do expect
another afternoon seabreeze along the coast.
Temperatures will be, comparatively, chilly tonight with many
localities falling into the upper 50s. Urban heat islands and the
immediate coastline look to remain in the low to mid 60s. For
Saturday, gradually warming temperatures aloft will tack a few
degrees onto highs, which will generally range in the low to mid
80s.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Highlights...
* Pleasant weekend weather with warm temps and comfortable humidity
* Unsettled with chances for some showers/thunderstorms next week
* Increasing humidity developing through the week
Details...
Sunday into Monday...
Guidance has continued to trend stronger with mid level low
developing off the SNE coast, but should not have much if any impact
on sensible weather during Sunday. Some of the guidance is hinting
at a potential warm core system but low pres and assocd moisture
will remain far enough offshore so expecting plenty of sunshine
Sunday with warm temps. Highs will reach mid-upper 80s, but a bit
cooler along the immediate coast as onshore breezes develop. There
will be a slight increase in humidity as dewpoints climb into the
60s.
For Sunday night into Monday, trend in the deterministic and
ensemble guidance brings increasing risk for some showers as mid
level low backs in toward SNE with increasing moisture. Shower
chances Sun night will be highest near the coast, then there is
uncertainty with favored location of any showers and thunder
potential Monday which will depend on track and positioning of the
mid level low and cold pool. Will have 20-30% PoPs for Mon to
reflect this uncertainty. It looks cooler Mon with cooling temps
aloft, with highs low-mid 80s interior and upper 70s near the coast.
Tuesday through Thursday...
Unsettled pattern during the period. Mid level low weakens and opens
up as it moves to the north but overall troughiness from the Gt
Lakes to the NE with occasional shortwaves and increasing column
moisture supports increasing risk for showers and a few t-storms,
but low confidence on timing of showers. While it won't be raining
all the time, potential exists for locally heavy rainfall as PWATs
increase to 2+ inches. Highs will generally be in the 80s and it
will become rather humid as dewpoints climb above 70.
&&
.AVIATION /10Z FRIDAY THROUGH TUESDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
12Z TAF Update:
Through Saturday: High confidence
VFR through Saturday evening with some afternoon mid level
cumulus development both today and tomorrow around 5,000ft. NW
winds persist for interior terminals but an afternoon seabreeze
is likely this afternoon for coastal terminals as AM gusts to
20kt gradually subside through the day. Near calm conditions
overnight tonight and into Saturday. Another afternoon seabreeze
likely for coastal terminals Saturday PM.
KBOS TAF...High confidence. VFR. NW flow, with gusts to 20kt
this morning giving way to winds less than 10kt this afternoon.
Seabreeze likely after 19Z today. Seabreeze again likely
Saturday but earlier in the day due to lack of gusty morning
winds.
KBDL TAF...High confidence in TAF. W/WNW around 10-12 kt gusts
20kt. VFR with NW winds around 10 kt, decreasing during the day
today.
Outlook /Saturday Night through Tuesday/...High confidence.
Saturday Night through Sunday: VFR.
Sunday Night through Monday: VFR. Slight chance SHRA.
Monday Night through Tuesday: Mainly VFR, with local MVFR
possible. Slight chance SHRA, isolated TSRA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Friday and Friday Night: High confidence.
NW gusts 15-20 kt thru late morning, with decreasing speeds into
the afternoon and become 10 kt or less for the evening. Seas 3
ft or less all waters. Dry weather.
Outlook /Saturday Night through Tuesday/...High Confidence
Saturday Night through Sunday: Winds less than 25 kt.
Sunday Night: Winds less than 25 kt. Chance of rain showers.
Monday: Winds less than 25 kt. Slight chance of rain showers.
Monday Night through Tuesday: Winds less than 25 kt. Seas
locally approaching 5 ft. Slight chance of rain showers,
isolated thunderstorms.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.
&&
$$
SYNOPSIS...KJC/KS
NEAR TERM...KJC/KS
SHORT TERM...KS
LONG TERM...KJC
AVIATION...KJC/KS
MARINE...KJC/KS
Source:
BOX issues Area Forecast Discussion (AFD) at Jul 26, 6:40 AM EDT----------------
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