Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 291144

Area Forecast Discussion
National Weather Service Raleigh NC
745 AM EDT THU SEP 29 2016

A potent upper level low will stall over the Cumberland Plateau in
eastern Tennessee and Kentucky today and Friday, then retrograde north
through the Ohio valley and lower Great Lakes this weekend.


As of 445 AM Thursday...

A busy midnight shift here in central NC, one which began with a
severe thunderstorm watch and transitioned into a 100-year rainfall
event (ongoing at ~09Z) across portions of the Sandhills (i.e.
Hoke/Cumberland/Harnett counties) where as much as 5-8" of rain has
fallen over the past 8-12 hours. As such, the forecast discussion
this morning will be brief. Several SW-NE oriented lines of
convection developed over central NC yesterday afternoon/evening in
assoc/w moderate diurnal destabilization, low-level convergence
attendant a pre-frontal trough, and diffluent flow aloft downstream
of a potent upper level low. During the overnight period, rich low-
level moisture assoc/w southerly flow in advance of the approaching
cold front has maintained sufficient nocturnal instability for
convection to persist, resulting in significant rainfall and
/potentially life-threatening/ flooding across portions of Harnett,
Hoke and Cumberland counties this morning.

Although the cold front may make some slow eastward progress into
the area today, the parent upper level low will cut-off /stall/ over
the TN valley this aft/eve, and additional eastward progress of the
front is unlikely thereafter. As a result, expect a good chance of
convection again this aft/eve into tonight. A few severe storms
cannot be ruled out, and an isolated flash flood potential will
persist. -Vincent


As of 445 AM Thursday...

On Friday, expect conditions similar to Thursday with the upper
level low stalled over the Cumberland Plateau and the attendant cold
front stalled over central NC. -Vincent


As of 440 AM Thursday...

Stubborn upper level low over the Southern Ohio valley will lift
slowly north,  back over the Great Lakes through the weekend. At the
surface, the lingering orphaned surface front will dissipate across
the area.

With Central NC on the eastern periphery of the deep cyclonic flow
and the back-edge of the deeper moisture plume (PWATS
~1.5")lingering over the coastal plain of NC, we`ll continue to see
a threat of mainly diurnal isolated to widely scattered showers
Saturday and Sunday, diminishing in coverage with each passing day.
Temperatures will continue to run slightly above normal with highs
ranging from upper 70s north to lower 80s south.

The closed low over the Great Lakes will finally open up and weaken
as it finally ejects eastward, moving off the New England Coast
Monday and into Tuesday. In it`s wake, sfc high pressure building
east and south down the Atlantic Seaboard will bring cooler, more
seasonable temperatures to the area by Tuesday/Wednesday.

Large uncertainty looms for the latter half of the upcoming work
week with respect to Tropical Storm Matthew. The NHC official
forecast has Matthew near Eastern Cuba Monday evening, with
questions as to whether Matthew will get picked up and directed
northward by an upper level trough over the Gulf of Mexico. Stay
tune and check with the National Hurricane Center for the latest on
Matthew. Users are reminded that the average NHC track errors at
days 4 and 5 are on the order of 180 and 240 miles, respectively.


As of 745 AM Thursday...

Slow moving band of showers and thunderstorms will continue to move
east this morning and will impact KFAY and KRWI with Sub-VFR
conditions in heavy rain. Convective coverage and intensity should
gradually decrease this morning. In addition, the low (LIFR) stratus
is expected to lift and scatter to VFR with diurnal heating between
15-18z Thu.

That heating, in conjunction with lift supplied by a slow-moving
wave of low pressure and associated frontal zone, will also cause
showers and storms to re-develop by mid afternoon and linger into
the evening.

Outlook: Moist low-level air will continue to support early morning stratus/fog
Friday morning and possibly again Saturday morning. Otherwise,
Drier air is finally expected to filter into the region on
Friday, leading to improved aviation conditions through the weekend.





NEAR TERM...Vincent
SHORT TERM...Vincent
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