Turner Downs Forecast Discussion

000
FXUS62 KRAH 161537
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1035 AM EST Sat Feb 16 2019

.SYNOPSIS...
A surface low will track east along a cold front that will push
south of the area later this morning. Chilly high pressure will
build south into the region tonight into Sunday. A series of upper
levels disturbances and fronts tracking through the region will
result in very wet and unsettled conditions Sunday through the
upcoming week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1030 AM Saturday...

...Rain tapering off to areas of drizzle this afternoon as
temperatures fall...

Overview: The low-amplitude shortwave trough across the area this
morning will move offshore later this morning. In the meantime, a
back-door cold front is making it`s way south through central NC.
The front`s southward progression is temporarily being slowed down
by the weak surface low that will ride east along the front-across
southern portions of the state. Once the surface wave moves east of
the area, the front will regain it`s southward momentum and will
push south into Georgia and southern SC overnight before stalling.

Once the surface low and upper support slides east and offshore,
drying aloft will lead to the widespread rain across the area this
morning tapering off to drizzle during the early(western NC) to
mid(eastern NC)afternoon.  So far today, we have seen observed
rainfall amounts range from just under 0.25" across the NW Piedmont
to little over 0.75" across the southern Piedmont. An additional
0.10 to 0.25" of an inch is expected across eastern portions of the
area. Otherwise, additional rainfall amounts across the central and
western Piedmont counties will be light.

Temperatures behind the front have already fallen into the mid to
upper 30s across Va bordering counties. This trend of falling
temperatures will filter south through the remainder of the day with
southern counties falling into the 40s during the afternoon.

Skies should remain cloudy tonight as the cold high builds in from
the north, and the low level NE flow continues to transport colder
and drier low level air into our damming region. The next in line of
shortwave disturbances and resultant overrunning lift and
precipitation will hold off until after 12z Sunday. Lows tonight
ranging from near 30 north to mid 30s across the south.

&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
As of 228 AM Saturday...

Rain and falling temperatures again Sunday.

CAD appears that it will linger into Sunday. It will get reinforced
as a 1025+ mb high is forecast to extend south into our Piedmont
damming region (even into northeast GA) Sunday. The high is
progressive to the north, cutting off our supply of cold and dry air
Sunday afternoon from the north. However, the next southern branch
wave will be moving in late Sunday morning through the afternoon,
with presumably another cold rain. This presumption is confirmed by
the forecast partial thicknesses that suggest the cold rain as well.
However, the coldest ensemble runs of the models suggest that the
surface wet bulb temperatures will be as low as 30 in the Triad to
Roxboro Sunday afternoon into the evening. There may be some light
icing on elevated surfaces (above the highway system) if this
verifies. Otherwise. evaporative cooling of the 20s (dry) dew points
in the NW and N Piedmont should again lead to falling temperatures
in the damming region again Sunday as the rain falls. Highs 40 NW to
some 50s SE, but falling into the lower 30s west and north and near
40 SE by late Sunday with the rain. POP near 100 percent, and QPF
storm totals for round 2 in the 0.5 to 0.75 range ending Sunday
night.

The cold rain should taper to areas of drizzle Sunday night. Lows in
the lower 30s NW and N ranging into the upper 30s SE. Too early to
forecast any freezing drizzle at the current time in the NW-N.
Otherwise, remaining cloudy and cold Sunday night.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 415 AM Saturday...

Monday through Tuesday morning: Aforementioned area of low pressure
will lift northeastward and away from the area on Monday, with
decreasing chances of rain and cloud cover. This will allow for
temps to recover on Monday, with highs on Monday in the 50s to 60s.
However, this will be temporary as yet another disturbance will
approach the region from the southwest in the southwesterly
mid/upper level flow. This will allow for mid and high clouds to
stream into the area on Monday night into Tuesday morning, with low
temps ranging from the mid 30s north to the lower 40s south.

Tuesday through Friday: Another CAD is expected to develop Tuesday
into Tuesday night continuing into Wednesday night, with lingering
affects into Thursday. This will result in widespread rain on
Tuesday night into Wednesday, with lingering chances for precip into
Thursday. This will yield generally cold high temps during this
period with fairly small diurnal range in temps, generally in the
upper 30s to 40s for highs. However, we could see the CAD boundary
retreat into far southeastern portions of central NC by Wednesday.
Medium range models continue to flirt with possibly some wintry mix
on Tuesday night across the Piedmont, though will keep the p-type as
all rain for now (low confidence). Otherwise, all rain is expected.
The complex low pressure configuration will lift off to the
northeast on Thursday, resulting in decreasing chances for precip
again, though models differ on how soon the next disturbance tries
to spread more precip into the area. For now will show temps
moderating some by the end of the week, with just a chance pops for
rain.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
As of 635 AM Saturday...

Areas of rain this morning, with widespread IFR to MVFR CIGS and
VSBYS. Rain to drizzle this afternoon, CIGS and VSBYS back to MVFR.

Outlook: Drier air will then spread swd from VA behind the area of
low pressure tonight, at which time ceilings may lift to MVFR
or even low VFR, particularly from Piedmont sites ewd to RWI.
However, another wave of low pressure will track across the
Carolinas and result in the redevelopment of rain and IFR-MVFR
conditions across cntl NC Sun and Sun night, followed by MVFR to VFR
conditions Mon through early Tue. Yet another wave of low pressure
will cross the Carolinas with another round of rain and sub-VFR
conditions late Tue and Tue night.

&&

.EQUIPMENT...
NWS radar engineers have discovered a problem with the lowest 2
radar elevation slices, particularly the 0.5 degree data is
seriously degraded. This will impact several radar products,
including rainfall estimates. Users should use the data with
caution. Sorry for the inconvenience. We appreciate your patience as
our engineers and technicians troubleshoot the problem.

&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...CBL/Badgett
NEAR TERM...CBL
SHORT TERM...Badgett
LONG TERM...BSD
AVIATION...BSD/PWB

NWS RAH Office Area Forecast Discussion