Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
444
FXUS61 KLWX 182355
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
755 PM EDT Tue Jun 18 2024
.SYNOPSIS...
High pressure will remain anchored offshore through the week,
resulting in a prolonged period of heat. The hottest days will
be Friday, Saturday, and Sunday.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
The few lingering afternoon showers dissipated very early this
evening. The cu field has mostly collapsed as diurnal heating
abates, and with that the Heat Advisory has also been cancelled.
Dry conditions overnight as the center of an upper high drifts
north and settles overhead. Lows tonight settle into the 60s for
most, with 70s metros and immediate shoreline.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
Center of upper high will be overhead Wednesday and Thursday
promoting large scale subsidence/sinking motion and inhibiting
t-storm development everywhere. Guidance indicates slightly
lower temps and dewpoints Wednesday likely as a result of low-
level flow coming off of the Atlantic Ocean and not from a
continental trajectory. Moderating a few degrees Thursday as the
ridge shifts back south.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
Upper level ridging along the East Coast will flatten out as we head
into the weekend. As this occurs, the 850 hPa high will shift to our
south, which will cause 850 hPa flow to turn southwesterly. This
will result in a more continental source region for the airmass and
even hotter temperatures. High temperatures in the mid-upper 90s
appear likely Friday through Sunday, with 100 degrees not entirely
out of the question. Dewpoints will also increase into the upper 60s
to lower 70s during that time, causing it to feel more humid than
preceding days. Heat indices in excess of 100 appear likely during
that time for much of the forecast area. There will be lesser relief
at night as well, as overnight lows increase into the middle to
upper 70s by the weekend to the east of the Blue Ridge (upper 60s to
lower 70s further west).
The combination of rising surface temperatures and dewpoints, along
with decreasing temperatures aloft as the upper ridge breaks down
will lead to an increase in instability, decrease in capping, and a
return to thunderstorm chances each afternoon and evening.
Thunderstorm activity is expected to remain relatively isolated on
Friday, and primarily confined to locations west of the Blue Ridge.
Thunderstorms coverage should increase slightly on Saturday as mid-
level heights continue to slowly fall. Most model guidance shows a
well defined upper trough tracking through the Great Lakes sometime
during the Sunday-Monday timeframe, but there`s variance in timing
between the individual models. As large scale ascent associated with
that trough increases, so will the coverage of afternoon and evening
thunderstorms.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions tonight through the end of the week. SE winds
around 10kt during the day becoming S around 5kt at night.
Prevailing VFR conditions and southerly winds are expected at the
terminals on Friday and Saturday. A stray afternoon or evening
thunderstorm can`t be ruled out either day.
&&
.MARINE...
SCA conditions continue through very late evening in the middle
to lower Chesapeake Bay and Lower Tidal Potomac, where frequent
gusts to 20 knots are expected. Elsewhere, occasional gusts to
20 knots are possible this evening.
South to southeast winds prevail through much of the week. Winds
may near low-end SCA levels in channeled southerly flow during
the afternoon/evening hours on both Friday and Saturday.
&&
.TIDES/COASTAL FLOODING...
Persistent southerly flow continues, and tidal anomalies are
hovering near one foot above normal. Sensitive areas will reach
action stage around times of high tide.
&&
.CLIMATE...
Hot temperatures are expected much of this week and especially
this coming weekend. The hottest days appear to be Friday through
Sunday when several records could be in jeopardy. Below is a list
of record high temperatures for today Jun the, 21st, 22nd, and
the 23rd and the year the record was set, and the current
forecast high temperatures for those days. RERs are only issued
for DCA, IAD, BWI, and MRB, but other sites are shown for
reference.
Tuesday Jun 18th
Climate Site Record High Forecast High
Washington-National (DCA) 97F (1944) 91F
Washington-Dulles (IAD) 94F (2018+) 93F
Baltimore (BWI) 97F (1957+) 92F
Martinsburg (MRB) 99F (1943) 92F
Charlottesville (CHO) 96F (2014+) 93F
Annapolis (NAK) 96F (1957) 87F
Hagerstown (HGR) 95F (1957) 94F
Friday Jun 21st
Climate Site Record High Forecast High
Washington-National (DCA) 99F (2012) 97F
Washington-Dulles (IAD) 98F (1988) 98F
Baltimore (BWI) 100F (2012+) 96F
Martinsburg (MRB) 102F (1931) 95F
Charlottesville (CHO) 99F (1933) 97F
Annapolis (NAK) 100F (1988) 91F
Hagerstown (HGR) 97F (1923) 97F
Saturday Jun 22nd
Climate Site Record High Forecast High
Washington-National (DCA) 101F (1988) 99F
Washington-Dulles (IAD) 99F (1988) 99F
Baltimore (BWI) 100F (1988) 98F
Martinsburg (MRB) 102F (1933) 96F
Charlottesville (CHO) 101F (1933) 99F
Annapolis (NAK) 101F (1988) 93F
Hagerstown (HGR) 100F (1988) 97F
Sunday Jun 23nd
Climate Site Record High Forecast High
Washington-National (DCA) 98F (1988) 96F
Washington-Dulles (IAD) 96F (1988) 97F
Baltimore (BWI) 97F (2010) 95F
Martinsburg (MRB) 100F (1934) 92F
Charlottesville (CHO) 100F (1894) 97F
Annapolis (NAK) 98F (1988) 91F
Hagerstown (HGR) 98F (1988) 94F
+ indicates that value has been reached on multiple years, with
the year displayed being the most recent.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 1 AM EDT Wednesday for ANZ532>534-
537-540-541-543.
&&
$$
SYNOPSIS...CPB
NEAR TERM...KRR/CPB
SHORT TERM...CPB
LONG TERM...KJP
AVIATION...KRR/CPB/KJP
MARINE...KRR/CPB/KJP
TIDES/COASTAL FLOODING...CPB
CLIMATE...LWX