005 
FXUS62 KRAH 140234
AFDRAH

AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
1033 PM EDT Tue Jul 13 2021

.SYNOPSIS...
On the western periphery of a sub-tropical ridge centered between 
Bermuda and the middle Atlantic coast, a series of mid to upper 
level disturbances will track northeastward across the southern 
middle Atlantic through Wednesday night.  

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1000 PM Tuesday...

Water vapor satellite showed a strong upper ridge just off the NC 
coast, and an upper trough digging across the Ohio Valley. Scattered 
showers and isolated thunderstorms have diminished this evening due 
to loss of diurnal heating. Conditions should remain stable enough 
to prevent any additional convection overnight. Moist, southerly 
flow will help develop another round of stratus tonight, mainly 
across the Sandhills and Coastal Plain. Lows: upper 60s to low 70s.

&&

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

On the wrn periphery of a persistent sub-tropical ridge centered 
between Bermuda and the middle Atlantic coast, a mid/upr-level 
vorticity max centered about 50 miles east of SAV this afternoon 
will likely have reached sern NC by 12Z Wed, after which time it 
will lift newd across ern NC and offshore the Outer Banks by late 
Wed afternoon-evening. Meanwhile, a shortwave trough over the ern 
Dakotas and nern NE this afternoon will amplify across the OH Valley 
and into the cntl Appalachians by Wed evening, then to the srn 
middle Atlantic coast by 12Z Thu. The divergent, right entrance 
region of an associated upr-lvl jet will glance cntl NC during the 
afternoon and early nighttime hours. 

At the surface, a persistent pattern of high pressure centered 
offshore the sern US coast and an Appalachian-lee trough will 
remain, with the latter forecast to again drift into/across the NC 
Piedmont through Wed evening. 

With persistence high temperatures of upr 80s-lwr 90s, and an 
associated moderately unstable airmass in place with heating Wed, 
the synoptic pattern described above should support the relative 
best coverage of showers/storms so far this week --focused first 
over ern NC and then across the wrn and nrn NC Piedmont, and with 
the highest probability of being maintained as they propagate esewd 
into the vicinity of Highway 64 through the first half of the night. 
Despite the modest forcing for ascent noted above, shear will remain 
too weak for anything more than multi-cell modes capable of 
producing strong wind gusts. 

Aside from that lingering nighttime convection, a persistence night 
of lows in the lwr-mid 70s and late night-early morning stratus/fog 
favored across the Sandhills and srn Coastal Plain will be followed.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
As of 300 PM Tuesday... 

The persistent weather pattern will largely continue through the 
weekend and into early next week. Relatively high pressure aloft 
will sit over the Carolinas through at least Saturday while a 
sheared out upper trough sits to the northwest (extending from the 
Northeast to the mid-MS Valley). This trough will slowly amplify and 
move eastward through the weekend, possibly into the mid-Atlantic 
late weekend/early next week. Similarly at the surface, high 
pressure will sit just off the Carolina coast through Friday before 
dissipating and getting absorbed into the larger Bermuda. However 
the latter will continue ridging westward into the Southeast US 
through the weekend. A piedmont/lee trough will be a daily feature 
over central NC, providing a focus for diurnally-driven convective 
activity (primarily over the foothills and Piedmont). A cold front 
will approach from the northwest as the upper trough moves into the 
region. There is still too much uncertainty with respect to when/if 
the front will make it into the area. If it does, it would be the 
best shot for an airmass change in the extended forecast period. 
Otherwise the warm, humid weather will persist. Highs in the upper 
80s to low 90s and lows in the upper 60s to low 70s will persist 
through Saturday, with the possibility of a slight downward trend 
thereafter.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 745 PM Tuesday... 

Isolated SHRA near KRDU this evening will diminish shortly after 
sunset. VFR conditions are expected for most locations tonight, with 
IFR-MVFR stratus/VIS possible near KFAY and KRWI by late tonight. 
Conditions will quickly improve across the region Wed morning, then 
Iso/Sct SHRA/TSRA will develop in the afternoon and early evening. 

Outlook: Stratus will likely develop each morning, with SHRA/TSRA 
developing in the afternoon-evening through Sunday.

&&

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

&&

$$ 
SYNOPSIS...MWS
NEAR TERM...JJT
SHORT TERM...MWS
LONG TERM...KC
AVIATION...JJT