textproduct: Raleigh

WHAT HAS CHANGED

As of 755 PM Wednesday...

* Increased Fire danger has been issued for Thursday. The aviation discussion was also updated.

KEY MESSAGES

As of 330 PM Wednesday...

1) Isolated convection with strong wind gusts possible over the far nw Piedmont between mainly between 6P-9P.

2) Increased fire danger will continue through at least Thu. A statewide burn ban remains in place, which prohibits all open outdoor burning until further notice.

3) Isolated showers and storms are possible mainly in the western Piedmont on Friday and Saturday. More-widespread showers and storms are expected on Sunday/Sunday night with a cold frontal passage.

DISCUSSION

As of 330 PM Wednesday...

KEY MESSAGE 1... Isolated convection with strong wind gusts possible over the far nw Piedmont this evening, mainly between 6P-9P.

Already steep low-level (0-3km) lapse rates ~9 C/km, per 19Z SPC mesoanalysis data, will further steepen with continued strong surface heating into the lwr-mid 80s throughout the Carolinas and VA this afternoon. Related surface dewpoint depressions around 25F will favor strong diabatic cooling potential and outflow development and maintenance, as will DCAPE between 750-1000 J/kg. As such, convection that developed due to orographic circulations over the Blue Ridge will probably continue to propagate generally ewd along common, mulit-cell outflow and to near and especially just northwest of the Triad through this evening. It will do so despite a lack of large-scale forcing for ascent over NC, between a strong ridge over the cntl and wrn N. Atlantic and a shortwave trough that will pivot across the cntl Plains. Even in the absence of convection reaching the nw Piedmont with much needed rain, gusty outflow winds of up to 30-40 mph will be possible before convection wanes/dissipates with loss of heating.

KEY MESSAGE 2... Increased fire danger will continue through at least Thu. A statewide burn ban remains in place, which prohibits all open outdoor burning until further notice.

NC forestry officials remain concerned about the very dry fuel moisture, relative humidity values in the 35-45 percent range, and marginally strong and gusty surface winds - all of which are forecast to generally continue until the next cold front and accompanying convection move across the state on Sunday. After coordination with NCFS earlier this afternoon, it was agreed that the Fire Danger Statement should continue through at least Thursday, then assess the need for a continuation in subsequent days. RH may reach a relative minimum on Thu, when a pocket of dry air just off the NC coast this afternoon is forecast to be advected inland and cause surface dewpoints to "mix out"/vertically-advect into the lwr- mid 50s F, with related min RH between 35-40% Thu afternoon.

KEY MESSAGE 3... Isolated showers and storms are possible mainly in the western Piedmont on Friday and Saturday. More-widespread showers and storms are expected on Sunday/Sunday night with a cold frontal passage.

Isolated showers and storms will be possible on Friday and Saturday afternoons as the mid-level high begins migrating back east in response to a trough pushing east over the Central US, and as southerly flow around a Bermuda surface high advects moisture off the Atlantic. This chance will be mostly confined to the western Piedmont (west of the Triangle) which will be furthest removed from the high pressure and where some orographically-enhanced convection may trickle east from the Mountains and Foothills. Can't rule out isolated seabreeze convection moving into our SE zones as well. GEFS and GEPS mean QPF has trended drier on average, and WPC now has zero QPF across central NC, on both days. Despite high temperatures reaching the lower-80s Friday and lower-to-mid-80s Saturday, given poor mid-level lapse rates and surface dew points mixing out into the 50s, CAPE looks to be less than 500 J/kg both days and there will be a lack of forcing. Thus convective coverage is expected to be very limited. Also not expecting any organized severe threat with more pulse-type storms given the very weak mid-level flow.

More widespread showers and storms are expected on Sunday along and ahead of a strong cold frontal passage. Mid/upper troughing will move across the Eastern US with resulting moderate mid-level height falls across central NC. Mid-level flow will increase to the 40-50 kt range, so shear could be sufficient for isolated strong to severe storms, but confidence is still low at this time given timing differences in guidance. The 12z ECMWF looks more similar to the GFS with a late afternoon/evening frontal passage, but the 00z run had been slower. A delayed frontal passage compared to earlier in the day would give more time for daytime heating and instability to build up. POPs are now in the categorical range, but ensemble mean QPF is generally a quarter to half an inch, which should still provide only limited relief from the ongoing drought.

Conditions behind the front from Monday through Wednesday will turn much cooler with highs mostly in the 60s and lows mostly in the lower-to-mid-40s. The region should also be largely free of precipitation early next week.

AVIATION /00Z THURSDAY THROUGH MONDAY/

As of 755 PM Wednesday...

Scattered convection continues over the northern highlands and Blue Ridge of NC this evening. While we cannot rule out a storm near INT/GSO until 02-03z, confidence has lowered in the last few hours. Satellite and regional radar are showing most of the convection staying to the west and northwest of INT/GSO, such that with reasonable confidence VFR should prevail this evening. A mixture of IFR-MVFR ceilings are favored in the 11-15z period, mainly in the Piedmont at INT/GSO and RDU. Confidence was high enough to include a prevailing MVFR ceiling at INT/GSO with model guidance appearing to support the deeper low-level moisture over the northwest Piedmont. Sub-VFR ceilings should lift by 15z, with south-southwest winds at times gusting Thu afternoon in the 16-18 kt range.

Outlook: Low-level moisture will gradually deepen and support increasing probabilities of early morning IFR-MVFR stratus particularly Fri and Sat mornings, and possibly again Sun, ahead of a cold front and chance of convection and flight restrictions that will move across cntl NC on Sun.

CLIMATE

Record High Temperatures:

April 1: KGSO: 90/1910 KRDU: 89/1974 KFAY: 87/2010

April 2: KGSO: 87/2010 KFAY: 90/1974

April 3: KFAY: 90/1934

April 4: KGSO: 87/2025 KRDU: 90/2025

Record High Minimum Temperatures:

April 1: KGSO: 63/2016 KRDU: 67/2016

April 2: KGSO: 61/1979 KRDU: 66/2024 KFAY: 66/2024

April 5: KFAY: 67/2025

RAH WATCHES/WARNINGS/ADVISORIES

None.