ragtop50
Member
RAH comments that they are putting more emphasis on the NAM solution
Saturday night through Sunday night: Winter Storm Watch in effect
from midnight Sunday through midnight Monday.
What has changed: Have slowed the arrival of the precipitation from
the south and thus a bit more cooler and drier air advects into the
area from the north ahead of the system. Also, have trended toward
the NAM solution given its consistency and tendency to better handle
these systems and CAD in general. As such and given the NAM
profiles, have trended a bit lower with snow totals (especially in
the west) and increased ice accum a bit due to a longer duration of
fzra and shorter duration of snow before the transition. There is
still some room for error and over performance of snow accumulations,
should the snow come down heavier in the northwestern Piedmont
and/or last longer before transitioning to fzra. Hopefully this will
get nailed down with subsequent forecast packages.
Aloft: A deepening closed low will swing eastward through the Deep
South and into the Southeast Saturday night through Sunday morning
then lift north into the mid-Atlantic along the Appalachians Sunday
aft/eve and continue lifting out of the area Sunday night.
At the surface: Cold high pressure will ridge south into the area
from a 1035 mb high sliding south from Quebec into the Northeast as
a strengthening low moves east through the Deep South and into the
Southeast Saturday night and early Sunday. The wedge over the
Piedmont will be quite strong, holding well into the day Sunday as
the low lifts into the Carolinas from the Southeast and the high
shifts off the New England coast on Sunday. The low should track
along and just inland of the NC coast Sunday evening and into the
DELMARVA by midnight or so Monday.
Confidence and Impacts: High confidence that a significant winter
storm will impact much of the NC Piedmont, though low confidence on
exactly where the p-type gradients will end up, as well as the
overall totals of snow, ice, and rain. Fairly high confidence on
timing, with precipitation beginning from the south after midnight
Sunday and exiting the area by midnight Monday. Regardless of the
totals, impacts are expected to be greatest along and west and north
of US-1, especially from Charlotte to the Triad to the Triangle,
with decreasing overall impacts with eastward/southeastward extent,
though overall precipitation totals should be highest over the
Coastal Plain.
Accumulations: Keeping in mind there will likely be a sharp gradient
in p-type accumulations across the area, generally expect highest
snow totals over the northern Piedmont (2-5 inches), highest ice
accumulations over the southern and western Piedmont (.1 to.3
inches), and overall liquid equivalent precipitation over the
Coastal Plain (1.8" or more).
Temperatures: Temperatures should decrease through Saturday night,
with lows bottoming out in the mid to upper 20s by Sunday morning.
Temperatures will slowly rise during the day and more so through the
evening as the low moves through the area, but highs will only rise
to around 30 degrees in the Triad, near 40 along US-1 and low to mid
40s across the Coastal Plain. Temperatures should hold steady or
drop only a couple/few degrees Sunday night.
Winds: The peak winds have increased and that trend may continue
with time as more hi-res data gets into the mix. Sustained winds of
15-20 kts with gusts of 25-30 kts are likely as the low moves
through the area on Sunday. -KCP
Saturday night through Sunday night: Winter Storm Watch in effect
from midnight Sunday through midnight Monday.
What has changed: Have slowed the arrival of the precipitation from
the south and thus a bit more cooler and drier air advects into the
area from the north ahead of the system. Also, have trended toward
the NAM solution given its consistency and tendency to better handle
these systems and CAD in general. As such and given the NAM
profiles, have trended a bit lower with snow totals (especially in
the west) and increased ice accum a bit due to a longer duration of
fzra and shorter duration of snow before the transition. There is
still some room for error and over performance of snow accumulations,
should the snow come down heavier in the northwestern Piedmont
and/or last longer before transitioning to fzra. Hopefully this will
get nailed down with subsequent forecast packages.
Aloft: A deepening closed low will swing eastward through the Deep
South and into the Southeast Saturday night through Sunday morning
then lift north into the mid-Atlantic along the Appalachians Sunday
aft/eve and continue lifting out of the area Sunday night.
At the surface: Cold high pressure will ridge south into the area
from a 1035 mb high sliding south from Quebec into the Northeast as
a strengthening low moves east through the Deep South and into the
Southeast Saturday night and early Sunday. The wedge over the
Piedmont will be quite strong, holding well into the day Sunday as
the low lifts into the Carolinas from the Southeast and the high
shifts off the New England coast on Sunday. The low should track
along and just inland of the NC coast Sunday evening and into the
DELMARVA by midnight or so Monday.
Confidence and Impacts: High confidence that a significant winter
storm will impact much of the NC Piedmont, though low confidence on
exactly where the p-type gradients will end up, as well as the
overall totals of snow, ice, and rain. Fairly high confidence on
timing, with precipitation beginning from the south after midnight
Sunday and exiting the area by midnight Monday. Regardless of the
totals, impacts are expected to be greatest along and west and north
of US-1, especially from Charlotte to the Triad to the Triangle,
with decreasing overall impacts with eastward/southeastward extent,
though overall precipitation totals should be highest over the
Coastal Plain.
Accumulations: Keeping in mind there will likely be a sharp gradient
in p-type accumulations across the area, generally expect highest
snow totals over the northern Piedmont (2-5 inches), highest ice
accumulations over the southern and western Piedmont (.1 to.3
inches), and overall liquid equivalent precipitation over the
Coastal Plain (1.8" or more).
Temperatures: Temperatures should decrease through Saturday night,
with lows bottoming out in the mid to upper 20s by Sunday morning.
Temperatures will slowly rise during the day and more so through the
evening as the low moves through the area, but highs will only rise
to around 30 degrees in the Triad, near 40 along US-1 and low to mid
40s across the Coastal Plain. Temperatures should hold steady or
drop only a couple/few degrees Sunday night.
Winds: The peak winds have increased and that trend may continue
with time as more hi-res data gets into the mix. Sustained winds of
15-20 kts with gusts of 25-30 kts are likely as the low moves
through the area on Sunday. -KCP
