textproduct: Raleigh

WHAT HAS CHANGED

* While rainfall amounts are still expected to be low, the chance for rain has gone up tonight, particularly across western counties.

* A Marginal Risk (Level 1 out of 5) for strong to locally severe wind gusts on Friday along and east of the I-95 corridor and as far west as the Triangle.

KEY MESSAGES

As of 210 PM Wednesday...

1) Although substantial rainfall is not expected tonight, the chance for showers will increase after midnight.

2) Shallow and isolated convection brings negligible rain amounts through Thurs with shower and storm chances maximizing ahead of and along a cold front on Fri.

DISCUSSION

As of 210 PM Wednesday...

KEY MESSAGE 1... Although substantial rainfall is not expected tonight, the chance for showers will increase after midnight.

There have been a few sprinkles through the late morning and early afternoon hours, but nothing that would accumulate. Although the primary round of accumulating rainfall will occur Thursday night into Friday, an upper level shortwave is expected to bring some rain to the area tonight. While rainfall amounts will not be terribly high (expect less than a quarter inch), models have trended upward with the chance for rain tonight, especially in the Triad. The coverage of showers should be rather isolated by sunrise on Thursday.

KEY MESSAGE 2... Shallow and isolated convection brings negligible rain amounts through Thurs with shower and storm chances maximizing ahead of and along a cold front on Fri.

Multiple lobes of mid/upper-lvl low pressure will make up a positively tilted trough axis stretching from Quebec into the Ohio Valley and back into the Southern Plains Thurs morning. Several pieces of vorticity will ripple through the broad cyclonic flow, slowly shifting the trough eastward, while additional northern stream waves reinforce the backside of the trough through Thurs night. Lack of mid/upper level forcing within broad neutral H5 height tendencies will keep convective coverage/intensity very limited despite increasing afternoon instability as low-lvl theta-e advection results in around 1000 SBCAPE, primarily across the Piedmont. Instability maximized in the lowest 3 km and a considerable amount of dry air in 3-8 km layer on the backside of a departing upper-lvl wave, will likely keep any afternoon convection shallow and limited to a quick burst of light rain and mostly isolated sprinkles through the afternoon and early overnight period.

A disturbance in the basal portion of the positively-tilted trough axis is expected to swing across the southern Plains and into the OH and TN Valley's early Fri morning the pivot across the Appalachians and Mid-Atlantic on Fri. Central NC will likely be glanced by 50-60m H5 height falls with deeper scale forcing 60-80m height falls and DPVA expected to remain to our north across the Mid-Atlantic through Fri afternoon/evening. A pre-frontal trough is expected to shift generally eastward across the Mid-Atlantic and Carolinas on Fri, preceding the cold front which will likely be bottled up against the windward side of the Appalachians until late Fri afternoon and evening.

Considerable cloudiness from stratus and perhaps some fog in the Coastal Plain and eastern-NC is expected Fri morning in addition to waves of elevated showers focused around upstream small-scale disturbances with better rain chances across the eastern Piedmont, Coastal Plain and Sandhills through the afternoon. Global numerical guidance varies quite significantly from the hi-res guidance with rainfall totals and there location through Fri evening; the former paints greater coverage of beneficial rainfall (1-3") across the area, while the latter favors mostly around or less than 0.5" for most locations with narrow swaths of enhanced rainfall (0.75-2") along the track of these upstream disturbances. This forecast package leans more heavily into the hi-res guidance and overall lower-end totals for most locations given limited coverage of instability > 1000 J/kg, glancing influences from better deep-layer forcing, questions on persistence of low overcast into the afternoon hours, and worsening drought over the Carolinas. The severe threat remains non-zero with low-predictability for Fri. Upper 60s dew points lifting into the area and overlapping 30-40 kts of 0-6 km shear will be favorable for providing instability and organization to any deepening convection. Gradually veering wind profiles, mainly in the mid/upper-lvls, with a steadily increase in magnitude with height will be favorable for multicell to transient supercell characteristics, but limited instability and potential storm interactions along the track of upstream disturbances may limit widespread storm longevity and associated severe threat. Primary risk would be localized strong wind gusts (30-50 mph) around and east of the I-95 corridor, although infrequent and brief severe wind gusts of 60 mph can't be ruled out given the uncertainty expressed above.

AVIATION /00Z THURSDAY THROUGH MONDAY/

As of 700 PM Wednesday...

Flight restrictions look probable at all TAF sites again tonight and into Thursday afternoon. Some light rain is currently moving through the western Piedmont. This may bring periods of MVFR ceilings and lowered visibilities if a shower moves over a terminal. Rain should continue overnight, mostly in the western Piedmont. Along with this, another round of low stratus/fog looks to develop over central NC tonight. Thus, IFR to LIFR ceilings will be possible at all sites. The existing cloud cover in the Triad may help keep these restrictions further to the east, with best confidence at RWI/FAY/RDU. Ceilings look to be slow to improve tomorrow, with RWI and FAY looking to return to VFR late afternoon, with RDU potentially staying MVFR until around 00Z, and INT/GSO remaining MVFR until after 00z.

Outlook: Another round of IFR/LIFR ceilings is forecast Thursday night into Friday. A cold front will bring rain to all terminals, primarily on Friday. Once rain comes to an end Friday night, dry VFR conditions are forecast for the rest of the time period.

CLIMATE

Record High Temperatures:

November 4: KGSO: 83/1946 KRDU: 84/1946 KFAY: 86/1974

November 5: KGSO: 82/1914 KRDU: 85/2003 KFAY: 86/2003

Record High Minimum Temperatures:

November 5: KGSO: 65/2003 KRDU: 66/1977 KFAY: 67/2003

RAH WATCHES/WARNINGS/ADVISORIES

None.