textproduct: Raleigh

WHAT HAS CHANGED

* Updated Aviation discussion.

KEY MESSAGES

As of 250 AM Wednesday...

1) A broken line of decaying showers is expected to move across the area this evening into tonight.

2) Hot, seasonably moist/humid, and with limited (slight chances of) diurnal convection this weekend through the middle of next week

DISCUSSION

As of 250 AM Wednesday...

KEY MESSAGE 1... A broken line of decaying showers is expected to move across the area this evening into tonight.

A srn stream s/w will shift off the Southeast US coast this morning then lift newd off the East Coast through tonight. Meanwhile, a nrn stream s/w will track across the region, helping to amplify/sharpen the parent trough as a low closes off within it over srn Ontario. The trough will generally remain over the East Coast on Thu while the low drops sewd across the nrn mid-Atlantic, both shifting offshore Thu night/Fri. At the surface, as the high shifts farther offshore today, the ridge extending wwd into the region between a low moving off the Southeast US coast and a cold front approaching from the NW will gradually weaken. Low-level moisture recovery still appears to be limited ahead of the cold front arrival this evening, which will greatly limit instability across the area. With that in mind, as noted in the previous discussion, the line of convection along and ahead of the front to weaken/decay as it moves into and across the area this evening and tonight and maintenance of deep convection appears unlikely. Cannot completely rule out a rumble of thunder over the NW Piedmont this eve, but chances continue to decrease. Rainfall totals will generally be a tenth of an inch or less across the area. High temperatures should top out in the upper 70s to low 80s. The cold front will move across the area this eve/tonight and be off the Carolina coast by Thu morn. Cool high pressure will gradually build ewd into the region in Thu/Thu night.

KEY MESSAGE 2... Hot, seasonably moist/humid, and with limited (slight chances of) diurnal convection this weekend through the middle of next week

A sub-tropical anticyclone in the mid-levels over nrn MX and wrn TX will progress across the srn US through the weekend, then amplify along or just off the South Atlantic coast early next week. Low amplitude, quasi-zonal flow, which will probably include both an EML plume and convectively-amplified disturbances, will prevail around it from the srn and cntl Plains to the Carolinas and Middle Atlantic this weekend.

Surface high pressure beneath and downstream of the associated ridge will extend from near Bermuda to the South Atlantic coast, while a trough will extend in the lee of the srn and cntl Appalachians and a sea breeze will move through the entirety of cntl NC each late afternoon-evening. Warm and seasonably moist sswly flow around the Bermuda high and across cntl NC will favor afternoon temperatures mostly in the lwr 90s and mixed dewpoints in the mid 50s-lwr 60s by Sun, with similarly hot and slightly more-humid conditions likely to continue through the middle of next week. An associated weakly unstable and weakly capped environment (with pockets of moderate instability possible) will become supportive of isolated/widely scattered convection - favored along the lee trough (nw Piedmont) and also along the sea breeze (Sampson Co.) through mid-evening, when nocturnal cooling and boundary layer stabilization should cause convective inhibition to become prohibitive to development.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

As of 648 AM Wednesday...

24 hour TAF period: VFR conditions should largely prevail the TAF period. There may be some clouds with bases in the 4-8 kft range across the south and east this morn/aft, but the better chance for 5- 8 kft cigs will be with the showers moving in from the NW this evening. Sly-sswly winds will increase this morning to 5-10 kts. There may be a general lull in winds after sunset before they become nwly and increase behind the front late. Expect a 20-25 kt LLJ to develop tonight, but for now it remains below LLWS criteria. Some guidance shows development of sub-VFR fog near KFAY and possibly KRWI tonight/early Thu morn, but confidence is not high on whether it will develop or impact the terminals.

Outlook: Any sub-VFR conditions that do materialize should return to VFR Thu morn and remain largely VFR through Sun, although some early morning sub-VFR fog is possible by Sun morn. Expect some gusty winds to around 20 kts on Thu, abating after sunset.

CLIMATE

Record High Temperatures:

May 17: KGSO: 94/1915 KRDU: 92/1947 KFAY: 97/1941

May 18: KGSO: 95/1911 KRDU: 95/1906 KFAY: 96/1911

Record High Minimum Temperatures:

May 17: KGSO: 69/1991 KRDU: 71/2025

May 18: KGSO: 70/2015 KRDU: 72/1896 KFAY: 71/2018

RAH WATCHES/WARNINGS/ADVISORIES

None.