WHAT HAS CHANGED
Patchy shallow fog has been developing early this morning, and
may expand a bit before lifting quickly after daybreak.
KEY MESSAGES
- 1) Dry through the end of October.
- 2) Precipitation chances return in early November.
DISCUSSION
KEY MESSAGE 1...Dry through the end of October.
Large scale ridging persists at the surface and aloft through
the end of the week. This results in dry weather and above
normal temperatures through the end of October.
Surface high pressure of Canadian origin that built over the
Mid-Atlantic this past weekend will drift South and West across
the Central Appalachians and Tennessee Valley through tonight.
This continues a gradual warming trend that began on Sunday.
A weakening cold front will approach from the North tonight,
tied to low pressure over the Canadian Maritimes. But without
much forcing or moisture, no precipitation is expected. The
front will cross the region Tuesday morning, then stall and
weaken, or perhaps lift Northward as a weak warm front, through
mid week. Warmer than normal temperatures will continue during
this time as a result.
Another large area of high pressure will build to the North for
the second half of the week. The position of the high should
allow for SouthEast to SouthWest winds and continued warm
temperatures by late October standards. The warmest day
currently appears to be Friday when highs in the mid to upper
70s are possible.
Saturday may be a few degrees cooler as clouds begin to increase
from the West ahead of a trough developing over the middle of
the country. Highs will likely still be above normal into the
lower 70s, however.
KEY MESSAGE 2...Precipitation chances return in early November.
Troughing developing over the Western CONUS late this week looks
to eject one or more pieces of shortwave energy this weekend.
This results in lowering heights and an approaching surface
frontal system as the calendar flips to November. There is a lot
of timing spread in the guidance on when these waves approach
our area, but some low precipitation chances do return to the
forecast by the end of the upcoming weekend.
AVIATION /06Z MONDAY THROUGH FRIDAY/
It`s a bit of a tricky forecast this morning due to a number of
competing factors surrounding potential fog. Low-level flow is
light out of the West, which typically inhibits fog, and the
background airmass isn`t terribly moist. However, very sharp
surface temperature inversions are evident early this morning,
resulting in shallow saturation. Whether this results in shallow
fog or just dew is the big question, with the greatest potential
for fog and IFR occurring right around daybreak when surface
inversions are at their sharpest. Confidence is modest, but
given IFR fog already developing in some sheltered piedmont
locations and widespread T/Td spreads of less than 2 degrees as
of 06Z, have inserted 1-3 hour TEMPOs around daybreak for IFR.
The notion of at lEast brief IFR fog is supported by the RAP,
HRRR, GLAMP, RRFS, and NAM/NAMNest...But not so much by the
MAV/MET or WRF-ARW/HRW-FV3.
Otherwise, VFR conditions are expected to prevail through the
upcoming week. Some light onshore flow Tuesday night through
Thursday could result in some late night/early morning sub-VFR
potential. Dry weather is anticipated with winds shifting from W
today, to NE Tuesday, then SE to SW Wednesday through Friday.
The next chance of precipitation does not arrive until the
second half of the upcoming weekend, but uncertainty is high at
this time.
MARINE
Light West to NorthWest winds are expected through this evening,
with a shift to the North and NorthEast and an increase behind a
dry cold front late tonight into Tuesday morning. Brief SCA
conditions are possible Tuesday morning, but whether it`s long
enough in duration to justify a Small Craft Advisory (versus a
Marine Weather Statement) is in question.
SouthEast to SouthWest winds are expected mid to late week as
high pressure builds to the North and NorthEast. Some channeling
is possible at times, though overall gradients look weak.
TIDES/COASTAL FLOODING
Tide levels remain a bit elevated, but anomalies continue to
slowly decrease overall. Further minor flooding is not expected
through the first half of this week.
LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...Frost Advisory until 9 AM EDT this morning for MDZ005-006-008-
503>508.
VA...Frost Advisory until 9 AM EDT this morning for VAZ037>040-050-
051-053-055-056-501-502-506-526-527.
WV...None.
MARINE...None.
