Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 202317

Area Forecast Discussion
National Weather Service Raleigh NC
717 PM EDT Mon May 20 2019

A cold front will cross central NC tonight. High pressure will build
into the region from the north Tuesday and Wednesday, providing a
temporary break from the heat. Hot temperatures will return for the
later half of the work week as high pressure aloft builds over the


As of 257 PM Monday...
A mostly dry cold front moving into western TN will cross the
area late this evening and through the overnight hours. Regional
mosaic radars showers a pre-frontal band of convection forming
along a pre-frontal sfc trough and vorticity shear axis
extending across the western Carolinas. This band is forecast to
fill in as it advances east into the NC Piedmont this afternoon
and early evening, followed by gradual weakening as the
convection advances into the Sandhills and Coastal Plain during
the late evening/early overnight.

Greatly limited by marginal shear parameters of only 15 to 20 kts,
severe threat will be quite low this afternoon/early evening with
the best chance of an isolated strong storm or two occurring across
the NC Piedmont counties, prior to 00z before nocturnal
stabilization begins.

The cold front will cross the Triad region around midnight and will
exit our far southeastern counties around daybreak. Nly winds behind
the front will advect a "cooler" though notably less humid air mass
into the area.  Overnight temperatures will vary from the near-lower
60s across the NW to the upper 60s SE.


As of 257 PM Monday...

Downstream of the mature upper low lifting north through the Central
Plains, the Sub-tropical ridge quickly re-establishes itself across
our region by Tuesday night. This gives concern that the cold front
may not clear the far southern zones entirely on Tuesday. If that
does indeed occur, future forecast updates may have to include some
small Pops across the far SE zones. Otherwise, expect dry conditions
to prevail on Tuesday with noticeably less humid conditions.
Temperatures will feature a fairly sharp north-south gradient
ranging from upper 70s/near 80 NE to near 90s south.

The arrival of more prominent surface pressure rises from the north
Tuesday evening/night will prove the needed force to push the front
into SC overnight. NELY low-level maritime flow Tuesday could advect
an area of sub-VFR ceilings across much of the area.  Min
temperatures ranging from lower/mid 50s NE to lower/mid 60s SW.


As of 230 PM Monday...

Still hot and dry for much of the long term forecast but a few
shortwaves to look at with respect to possible precipitation this
week. The first will be on Thursday as a low pressure system moves
across southern Ontario and northern New York. Models are in fairly
good agreement with regards to the location and strength of this
features, but not with respect to moisture. The strength of the
upper ridge comes into play and the ECMWF solution is still in favor
of what is probably the more likely solution in that the ridge
remains strong and any adverse weather has trouble penetrating
southward into the CWA. Will carry slight chance pops across the
north with scattered thunderstorms possible Thursday afternoon and

The same can be said for a second low pressure system on a similar
track to the first that lays a frontal zone down from east to west
across the mid-Atlantic States. Again, the GFS is in favor of a more
southward solution, one that is perhaps ignorant of the strength of
the upper ridge. If the front does make way southward, there could
be another slight chance for showers Sunday night into Monday, and
again Monday afternoon if leftover boundaries remain over the area.
Not a washout by any means and certainly looking like mostly dry
weather for the Memorial Day Weekend but warmer than we are used to
this time of year.

Temperatures will start out cooler on Wednesday in the low to mid 80s
from NE to SW but as the ridge begins to strengthen, thickness
values increase allowing for low 90s across the area on Thursday
afternoon. Temperatures will continue to rise into the mid 90s for
the rest of the period. With dewpoints in the mid 60s, heat indices,
while uncomfortable should stay below advisory criteria with 95-100
degrees expected from Friday through Monday. We do recommend taking
precautions if outside for long periods of time this weekend,
especially for those particularly susceptible to the heat.


As of 720 PM Monday...

A mid-level shortwave is currently pushing across central North
Carolina this evening with showers and a thunderstorm or two
developing. Vertical temperature profiles on forecast soundings
though show a substantial mid-level isothermal layer which will
likely keep most development lightning and thunder free. Later
tonight the surface cold front will swing through the area with
winds turning from the west/northwest. Along the front only weak
scattered showers are expected at best as the saturated layer
remains thin. During the day Tuesday a cold front will clear the
TAF sites with VFR conditions expected.

Looking beyond 00z Wednesday: Wednesday morning IFR/ MVFR
stratus will quickly develop as low level winds veer around from
the southeast. Another round of ceiling and visibility
restrictions will be possible early Thursday morning. Otherwise,
strong upper level ridging will result in predominately VFR
parameters through the weekend.




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