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000 
FXUS62 KRAH 261147
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
747 AM EDT Tue Sep 26 2017

.SYNOPSIS...
A narrow ridge of high pressure will remain centered over the 
Appalachians through Wed, while Hurricane Maria tracks northward, 
offshore the coast of the Carolinas. Meanwhile, a dry cold front 
will approach from the northwest, then cross NC late Thu and Thu 
night.   

&&

.NEAR TERM /THROUGH TONIGHT/... 
As of 340 AM Tuesday...

A mid level ridge now centered over the nrn middle Atlantic states, 
and underlying surface ridge extending from New England swwd along 
the Appalachians, will both weaken during the next 24 hours, as 
height falls aloft from Hurricane Maria and a shortwave trough 
lifting across the nrn Plains both converge upon the ridge. This 
development will ultimately cause Maria to turn ewd and away from 
the NC/VA coast later Wed and Wed night. Until that time, however, 
the MSL pressure gradient between Maria and the (weakening) ridge 
will result in both the continued wwd expansion of a low overcast 
this morning, and the development of breezy conditions with diurnal 
heating over the ern half of the forecast area (from the ern 
Piedmont and Sandhills to the Coastal Plain). Resultant partly sunny 
conditions over the wrn Piedmont, to mostly cloudy ones over the 
Coastal Plain, will result in an atypical temperature distribution 
characterized by middle to upper 80s west to upper 70s to lower 80s 
east. 

Initially partly to mostly clear skies this evening will become 
cloudy or mostly so over portions of the Coastal Plain and ne 
Piedmont, as moist nely flow will favor the wwd expansion of low 
overcast there once again overnight. Lows will range from the middle 
60s to lower 70s, mildest east owing to both the aforementioned low 
clouds and a continued nly breeze. 

&&

.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... 
As of 355 AM Tuesday...

Based on the official NHC forecast track, by-then Tropical Storm 
Maria will be ~150 nm east of HSE by 12Z Wed, after which time a 
turn to the east and an increase in forward speed will occur. The 
low level flow will consequently back to a (drier) nwly to nnwly 
direction and result in partly to mostly sunny conditions on Wed. 
Projected low level thickness values around 1425 meters at GSO will 
favor well above average temperatures in the upper 80s to lower 90s. 
Lows in the 60s. 

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 325 AM Tuesday...

Thursday will be our final unseasonably warm day as Maria 
accelerates eastward and a dry cold front pushes south down the 
Atlantic coast. Highs Thursday will reach the mid and upper 80s, 
with some lower 90s possible along the southern tier of central NC. 
Strong cold air advection will be getting underway Thursday night as 
high pressure builds east across the Mid Atlantic. This high 
pressure will then surge south down the Atlantic seaboard over the 
weekend, with highs falling to mostly upper 70s on Friday, and even 
further to mostly the mid to upper 70s though Monday. Mins will 
similarly fall from 60 to 65 Friday morning to the low and mid 50s 
Saturday through Monday.  

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/ 
As of 745 AM Tuesday...

A shield of IFR-MVFR ceilings, in moist nely low level flow on the 
nwrn periphery of Hurricane Maria, will lift and scatter to VFR by 
this afternoon, though they may persist in the 2000-3000 ft range 
all day at RWI. The low clouds will then edge wwd once again 
tonight, in a similar fashion as right now, though they will likely 
not make it much farther wwd than RWI (to perhaps near or just east 
of RDU) at that time. It will also become breezy with diurnal 
heating today, mainly at RWI/FAY/RDU, owing to the MSL pressure 
gradient between Maria and high pressure centered over the 
Appalachians. Lastly, an isolated shower will be possible this 
afternoon, mainly at RWI.

Outlook: Any lingering IFR-MVFR ceilings Wed morning at ern TAF 
sites will quickly lift and scatter to VFR, as Maria accelerates ewd 
and loses influence (Ie. the flow will assume a drier nwly 
component), with a subsequent long stretch of mainly VFR conditions 
for the next several days. 

&&

.CLIMATE...

Record high temperatures across central NC for September 27 and 
28.

        RECORD MAX (9/27)       RECORD MAX (9/28)
RDU         94 / 1998               95 / 1998
GSO         90 / 2007               92 / 1939
FAY         94 / 1986               95 / 1933

&&

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


$$

SYNOPSIS...MWS

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