596
FXUS61 KALY 171040
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
640 AM EDT Mon Jun 17 2024

.SYNOPSIS...
Hot and humid weather arrives today, reaching dangerous levels
Tuesday through Thursday mainly for valley locales, before
slowly receding into the weekend. Isolated to widely scattered
diurnal showers and thunderstorms are possible Tuesday through
the end of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
.UPDATE...As of 0630 AM EDT, despite scattered high cloud
coverage, calm to light winds across the southeastern
Adirondacks and Upper Hudson Valley has allowed for efficient
radiative cooling to yield morning lows in the upper 40s to mid
50s, while other areas have remained in the mid 50s to low 60s.
Nonetheless, ample warming is expected beneath clearing skies
this afternoon, although a few showers may reach into the
southern Adirondacks as upstream radar returns show a coherent
area of rain tracking toward the St Lawrence Valley associated
with a passing upper shortwave. As such, forecast remains on
track; see previous discussion below...

.PREV DISCUSSION [0515 AM EDT]...Upper ridging amplifies over
the region today with a closed mid-level high building over the
Mid-Atlantic and Carolinas while surface high pressure remains
located southeast of Cape Cod. Low-level southerly flow about
the western flank of the surface high will aid in advecting
moist air northward into the region, while upper heights
steadily rise overhead as 850 hPa temps reach 16-18C. At the
surface, temperatures will rise around 10 degrees above normal,
reaching afternoon highs in the upper 70s to low 80s in high
terrain and mid 80s to around 90 degrees at lower elevations.
With dewpoints rising into the 60s across the region, heat
indices will reach the low to mid 80s above 1000 feet, with
upper 80s to low 90s at lower elevations.

A weak shortwave passing to the north may result in a few rain
showers across the southern Adirondacks, before the impulse
exits to the northeast this afternoon ahead of the developing
ridge. Scattered clouds this morning will thus give way to
mostly sunny skies through the afternoon and evening.
Conditions will remain muggy and mild tonight, as temperatures
only fall to lows in the 60s across the region.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
**Heat Advisories are now in effect noon Tuesday through 8 PM
 Thursday for all of eastern New York and western New England**

Dangerous levels of heat and humidity arrive across the region
Tuesday. Heights aloft will continue to rise through much of
Wednesday as the closed 500 hPa high amplifies to nearly 600 dam
while drifting north and east toward the region. Height
anomalies remain only a +2 to +3 sigma event per latest NAEFS
output, however the narrower historical distribution of high
pressure still renders this event outside the CFSR climatology,
indicating height anomalies of this magnitude have likely not
occurred at this time of year in the last three decades.

850 hPa forecast temperatures remain around 18-21C, which do
not represent as significant of an anomaly, only +1 to +2 sigma,
but may nonetheless result in surface temperatures which
challenge daily records across the region. Despite deep mixing,
it may be difficult for surface temperatures to reach 100
degrees given the lack of more substantial temperatures
anomalies aloft. Nonetheless, dangerously hot and humid
conditions are expected, as temperatures reach afternoon highs
in the mid 80s to low 90s in high terrain and mid to upper 90s
at lower elevations both Tuesday and Wednesday. Surface
dewpoints in the mid 60s to low 70s will yield heat indices in
the 90s above 1000 feet and 100-105 degrees for valley locales.
Conditions will remain mild and muggy through the overnight
hours, as overnight lows remain stuck in the mid 60s to low 70s
across the region.

Despite heat indices in high terrain areas of the southern
Adirondacks and eastern Catskills potentially remaining below 95
degrees, and in collaboration with neighboring forecast
offices, have opted to expand Heat Advisory coverage to include
the entire forecast area as potentially record-setting heat this
early in the summer season with little relief available
overnight may result in more significant impacts to the local
population. As such, Heat Advisories are now in effect from noon
Tuesday through 8 PM Wednesday for all of eastern New York and
western New England. There remains potential for the Capital
District, Hudson Valley, and Connecticut River Valley to see
heat indices in excess of 105 degrees, which would result in the
issuance of Excessive Heat Warnings if confidence in their
occurrence and coverage increases in future forecast updates.

Isolated to scattered diurnal showers and thunderstorms are
additionally possible both Tuesday and Wednesday afternoons,
most likely across the southern Adirondacks and southern
Greens. Forecast temperatures are admittedly on the higher end
of guidance, and any increase in coverage of these showers or
storms could result in temperatures underperforming current
forecast highs, as supported by short-range ensembles.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Heat Advisories continue until 8 PM Thursday for all of
eastern New York and western New England...

Our long duration heat event continues into Thursday as our
impressive closed high featuring near 595 - 600dam heights (which is
+2 to +3 standard deviations above normal) centered over the mid-
Atlantic slowly pushes southward. Strong west-southwesterly winds
around it will continue to advect in an anomalously warm air mass
into the Northeast with 850hPa isotherms reaching +19C to +20C (also
+2 to +2.5 standard deviations above normal). This should support
afternoon high temperatures once again soaring into the mid to
possibly upper 90s for valley areas with upper 80s to low 90s in the
hill towns and high terrain. With dew points again reaching into the
60s to around 70, heat index values are expected to reach 100 -
104F. These values support the heat advisory we already issued and
if confidence for heat index values reaching or exceeding 105F
increase, excessive heat warnings may need to be issued for valley
areas. Considering this will be the third day of the oppressive
heat/humidity, heat impacts likely be become more noticeably.
Overnight low temperatures also will not provide much relief as
overnight lows only drop into the 60s to low 70s.

A wind shift boundary from the international border will be slowly
sinking southward on Thursday and looks to reach our southern
Adirondack and Upper Hudson Valley areas. Therefore, we continue to
show light chance and chance POPs spreading south into these zones
by Thursday afternoon. While the overall forcing and moisture is
rather lackluster, instability will be quite high given the
heat/humidity so if the boundary can provide enough forcing for
ascent, thunderstorms will easily develop.

Chances for showers and thunderstorms continue each day (especially
during the afternoon hours) Friday and Saturday as our boundary
continues to slowly push southward but again the overall thermal
gradient and available moisture along the boundary appears rather
weak. Even still, given how unstable to environment will be, it will
not take much lift to result in thunderstorms, especially the peak
heating hours. Given the increase cloud coverage from the incoming
boundary plus chances for showers/storm, temperatures Friday and
Saturday show a slight drop with highs "only" topping out in the
upper 80s to low 90s Friday and mid to upper 80s to around 90 in
valley areas on Saturday. Given this will be day 4 and 5 of the
hot/humid weather, heat impacts likely will be still be felt given
the lack of relief, especially for those populations without air
conditioning, even if some areas technically fall below the 95F heat
index threshold.

By Sunday, the wind shift boundary over the Northeast looks to lift
northward as a warm front and temperatures could turn hot once again
ahead of an incoming and stronger cold front. Still uncertainty on
exactly how and when this cold front occurs but the heat/humidity
looks to linger into a 6th day on Sunday with more organized area of
rain and thunderstorms possible later in the day Sunday or Sunday
night. Luckily, there are signs that relief from the heat/humidity
should finally arrive by the beginning of the new work week.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
VFR conditions expected to prevail for the majority of the time
through 12 UTC Tuesday. Cirrus clouds this morning will gradually
lower to a mid-level deck this afternoon by 18 - 20 UTC mainly
at ALB, GFL, and PSF as an area of showers from northern/western
New York weakens and dissipates on its tracks eastward. Then,
clouds clear mid to late this afternoon.

Southerly winds increase at all terminals by 13-15 UTC becoming
sustained 5-10kts with gusts up to 15kts. Winds turn light and
variable by 02-03 UTC/18 at all terminals.

Outlook...

Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: Low Operational Impact. Slight Chance of SHRA...TSRA.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: Low Operational Impact. Slight Chance of SHRA...TSRA.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: Moderate Operational Impact. Chance of SHRA...TSRA.
Friday Night: Low Operational Impact. Slight Chance of SHRA...TSRA.
Saturday: Moderate Operational Impact. Chance of SHRA...TSRA.

&&

.CLIMATE...
Record High Temperatures:

Tuesday June 18:
Albany - 97 (1957, 2018)
Glens Falls - 95 (1907)
Poughkeepsie - 94 (2018)

Wednesday June 19:
Albany - 94 (1995)
Glens Falls - 97 (1995)
Poughkeepsie - 92 (1941, 1943, 1993, 2016)

Thursday June 20:
Albany - 97 (1953)
Glens Falls - 97 (1923)
Poughkeepsie - 96 (2012)

Friday June 21:
Albany - 97 (1938)
Glens Falls - 96 (2012)
Poughkeepsie - 97 (1949)

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory from noon Tuesday to 8 PM EDT Thursday for
     CTZ001-013.
NY...Heat Advisory from noon Tuesday to 8 PM EDT Thursday for
     NYZ032-033-038>043-047>054-058>061-063>066-082>084.
MA...Heat Advisory from noon Tuesday to 8 PM EDT Thursday for
     MAZ001-025.
VT...Heat Advisory from noon Tuesday to 8 PM EDT Thursday for
     VTZ013>015.

&&

$$

SYNOPSIS...Picard
NEAR TERM...Picard
SHORT TERM...Picard
LONG TERM...Speciale
AVIATION...Speciale
CLIMATE...Rathbun