textproduct: Raleigh

WHAT HAS CHANGED

As of 120 PM Tuesday...

* Prolonged increased fire danger risk is expected to continue through Wednesday and another fire danger statement will be officially issued later this evening for Wednesday.

KEY MESSAGES

As of 320 PM Tuesday...

1) Increased fire danger continues today. A statewide burn ban remains in place, which prohibits all open outdoor burning until further notice.

2) Scattered showers and isolated storms are possible across the western Piedmont late Wed afternoon.

3) After mainly dry conditions on Thursday, isolated to widely scattered 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 320 PM Tuesday...

KEY MESSAGE 1... Increased fire danger continues today. A statewide burn ban remains in place, which prohibits all open outdoor burning until further notice.

NC forestry officials remain very concerned about the high risk for dangerous fire weather conditions today and again on Wednesday. The ongoing drought and paucity of rainfall in the last 90 days is contributing to very dry fuels and tree litter, and minimum RH is expected to be around 35-45% across all of central NC today, with frequent gusts in the 15-25 mph range. These factors all suggest the potential for rapid fire growth and spread today, and a burn ban remains in effect until further notice.

Looking ahead to Tue, the increased fire danger may persist, although to a lesser degree, given that frequent gusts to up to 20 mph will occur again tomorrow. Although RH values will likely be about 5% higher, this will have negligible impact on risk for rapid fire growth. Another increased fire danger statement will be needed for Wed and will be officially issued this evening.

KEY MESSAGE 2... Scattered showers and isolated storms are possible across the western Piedmont late Wed afternoon.

Continued southwesterly moisture/thermal advection in the low- lvls will support unseasonably warm temperatures (mid 80s) and limited diurnal mixing/lowering of afternoon dew points (upper 50s to low 60s). This will likely result in seasonably high instability (500- 1500 MLCAPE) over a majority of the Piedmont to the NC Foothills by Wed afternoon. Although convective temperatures may be met anywhere in this area and result in isolated/scattered showers, most hi-res guidance suggests the bulk of the convective chances/coverage will initially develop over the high terrain (orographic circulation forcing) and spill slowly eastward into the western Piedmont through the late afternoon and early evening hours.

Kinematics through the depth of the profile will be relatively weak and erratic due to proximity with the sub-tropical ridge over the western Atlantic. Moderately steep low-lvl lapse rates (> 8.5 C/km) and moderate DCAPE (> 800 J/kg) could support locally strong wind gusts (30-50 mph) provided deep convection is able to develop and sustain itself into our forecast area, which based on latest 12z guidance, may be very limited in coverage and duration.

KEY MESSAGE 3... After mainly dry conditions on Thursday, isolated to widely scattered 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.

The mid-level high over the western Atlantic will retrograde back westward on Thursday, resulting in weak height rises and a relative minimum in precipitation chances across central NC, with mainly dry conditions expected. Thursday could be another day of fire weather concerns given RH values dropping to 35-45% in the afternoon, wind gusts up to 20 mph, and the very dry fuels in place.

Isolated to widely scattered pulse-type convection will then be possible again on Friday and Saturday afternoons as the mid-level high begins shifting back east in response to a trough pushing east over the Central US. This chance will be highest over the western Piedmont which will be furthest removed from the subtropical ridge and where some orographically-enhanced convection may trickle east from the Mountains and Foothills. PW values will increase back to 150-200% of normal, and with highs mostly in the lower-80s, CAPE of a few hundred J/kg will be possible in the west. Guidance is showing potential for some seabreeze convection moving into our SE zones on Saturday as well. Due to the fairly weak instability and ensemble mean and WPC QPF generally around a tenth of an inch or less on average, convective coverage is expected to be low.

On Sunday afternoon and evening, more widespread showers and storms are possible along and ahead of a strong cold frontal passage. With mid-level flow in the 40-60 kt range, shear could be sufficient for isolated strong to severe storms, but confidence is still low at this time especially with instability continuing to look limited in the guidance. 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 on Monday and Tuesday will turn much cooler with highs in the 60s and lows in the lower-to-mid-40s. The region should also be largely free of precipitation early next week.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

As of 120 PM Tuesday...

High confidence in VFR conditions through the critical initial 6-9 hr window of the 18z TAFs. SCT/BKN 5-7 kft fair-weather cu and gusty southwesterly winds will continue over the forecast area through the daylight hours. An isolated shower may drift towards INT this evening, but chances are very low (< 10%) After sunset, wind gusts will gradually weaken along with diminishing cloud cover. Marginal LLWS is expected at the northern TAF sites as a surface inversion develops around 1,500 ft and flow increases to 40 kts.

Outlook: Isolated to scattered convection developing over the high terrain over western NC and drifting eastward into the Piedmont will be possible late Wed afternoon (15-35% chance) and again Fri afternoon (15-40%). Patchy early-morning fog and/or low stratus can't be ruled out Wed- Fri.

CLIMATE

Record High Temperatures:

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

April 2: KGSO: 87/2010 KRDU: 90/1967 KFAY: 90/1974

Record High Minimum Temperatures:

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

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

RAH WATCHES/WARNINGS/ADVISORIES

None.