textproduct: Raleigh

WHAT HAS CHANGED

As of 215 AM Friday...

updated with the latest TAF discussion and key messages.

KEY MESSAGES

As of 215 AM Friday...

1) Another strong cold front will shift across the region Monday and bring a risk for severe weather in the Coastal Plain.

DISCUSSION

As of 215 AM Friday...

KEY MESSAGE 1...Another strong cold front will shift across the region Monday and bring a risk for severe weather in the Coastal Plain.

Overall there is reasonably good confidence in the evolution of the mid/upper level pattern within the medium range. A more highly amplified system is expected to develop over the northern/central CONUS Sun and progress eastward into the Great Lakes into the TN Valley by Mon. At the surface this will result in a stationary boundary over the Carolinas to lift northward as a warm front Sun into Sun evening as surface high pressure strengthens off the Northeast coast while at the same time low pressure deepens over the OH Valley. Strengthening southwesterly flow will result in a narrow window of moisture return into the region ahead of yet another strong cold frontal passage.

The timing of the frontal passage continues to fluctuate by 3-6hrs with each cycle of deterministic guidance. We do appear to be narrowing in on a window from 18z to 06z from the fropa, with prefrontal convection as early as 15z until as late as 06z. An added complication appears to be a signal for a morning stratus layer, especially in the initially upslope region into the Piedmont. Instability still appears weak overall (500 J/kg or less and maximized over the Coastal Plain and Sandhills) and results in a highly conditional high-shear, low-cape setup. Mostly straight hodographs with 40-60 kts of deep layer shear oriented parallel to the cold front will favor strong to severe winds to be the primary severe hazard if a severe threat were to develop. Low-level shear of > 20 kts and 0-1 SRH of > 100 m2/s2 also suggests a low-end tornado threat can't be ruled out.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

As of 200 AM Friday...

VFR conditions will prevail across much of central NC through the 06Z TAF period, with the primary concern through early this morning with patchy dense fog across the Coastal Plain. Current 05z observations show fog developing from around Roanoke Rapids southward, and this may briefly impact eastern terminals, particularly KRWI and possibly KRDU through the early morning hours. Any fog that develops will lift and dissipate shortly after sunrise, returning conditions to widespread VFR by mid- morning. After sunrise, increasing south to southwest winds will develop as mixing strengthens. Winds will increase late morning into the afternoon with sustained speeds around 10-15 kt and gusts generally 20-30 kts, strongest across the Triad terminals (KGSO/KINT).

In addition, model soundings and guidance suggest a strengthening low-level jet tonight into early Saturday morning. This may result in a period of low-level wind shear possible at all terminals late tonight through early Saturday, as winds around 1.52 kft increase to around 3545 kt while surface winds remain lighter. Did not add to the 06z TAF package but will likely add to the 12z TAF package with more model data/consistency.

Outlook: VFR conditions are expected to dominate Saturday with sub-VFR conditions returning as early as Sunday evening. Gusty winds are also expected Sunday afternoon into Monday as the next weather system moves across the region.

RAH WATCHES/WARNINGS/ADVISORIES

None.