textproduct: Raleigh

WHAT HAS CHANGED

As of 310 AM Wednesday...

* Highs today continue to trend upward, setting additional records.

KEY MESSAGES

As of 310 AM Wednesday...

1) Record warmth again today with an air mass more typical of early July.

2) A strong cold front will bring widespread showers Thursday, with a few strong storms possible, mainly SE of the Triangle.

3) Another strong cold front will shift across the region late Sunday night into Monday and bring a low-end risk for severe weather in the Coastal Plain.

DISCUSSION

As of 310 AM Wednesday...

KEY MESSAGE 1... Record warmth again today with an air mass more typical of early July.

The earliest 90 degree high for so early in the season is possible at Raleigh (current earliest 90 degree high record is March 12, 1990).

The big weather story around central NC continues to revolve around record temperatures. Low level thicknesses are still expected to reach around 1410m, which is more typical of early July.

Some increase in high cloudiness in the afternoon may keep temperatures down a degree or two from current projections in the mid 80s NW and upper 80s to near 90 from Fayetteville to Raleigh.

These temperatures are likely to break additional warm records (see climate section).

SW winds will increase to 15-20 mph with gusts to 25 mph this afternoon. Peak winds around 30 are expected.

KEY MESSAGE 2... A strong cold front will bring widespread showers Thursday, with a few strong storms possible, mainly SE of the Triangle.

Confidence remains high in the timing of a strong cold front that will move NW to SE through central NC Thu, entering the Triad in the early morning hours and exiting our southeast during the mid to late afternoon. This cold front will be associated with a deep phasing mid level trough, currently unphased over the High Plains/Front Range down to far N Mexico. Moisture will be plentiful ahead of and with the front throughout the low levels (as the Gulf will be well tapped within a stout SW prefrontal flow starting late today) as well as the mid and upper levels (widespread deep convective debris clouds are evident ahead of the trough on WV imagery over the S Plains). Height falls and strong kinematics will contribute to robust forcing for ascent ahead of the front, but the degree of instability is less certain. Our NW half should see too many clouds and too early a frontal passage for much CAPE, but if our SE half can manage a little insolation, we could see several hundred J/kg of SBCAPE by the afternoon hours, as corroborated by the latest HREF. With high confidence in 40-50 kts of deep layer bulk shear, a few strong storms producing enhanced wind gusts are possible, mainly SE of the Triangle area, but overall the unfavorable timing of the front and the abundant prefrontal clouds yielding a limited window of insolation should keep both storm strength and number limited. Even outside of any storms, though, surface gusts up to 25-30 mph are likely Thu. Around a half to two-thirds of an inch of rain is expected from very late tonight through Thu, and this rain will be beneficial given the ongoing drought conditions. After very mild daybreak temps in the upper 50s to mid 60s across the area, temps will drop from NW to SE with frontal passage, into the 50s and 40s by mid to late afternoon.

KEY MESSAGE 3... Another strong cold front will shift across the region late Sunday night into Monday and bring a low-end 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.

Timing of the fropa remains a point of uncertainty, but based on cluster analysis, it appears to be sometime Mon morning to Mon afternoon. Although this will be slightly more diurnally favored to give time for the boundary layer to destabilize, instability still appears to weak overall (500 J/kg or less). Mostly straight hodographs with 40-50 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.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

As of 600 AM Wednesday...

VFR conditions are expected to prevail across central NC through 06z/Thursday. Light SW winds will increase late morning into the afternoon with gusts of 25kt.

Outlook: A 40-50 kt SW low-level jet may bring low-level wind shear conditions this evening. This may be offset by mixing that could keep SSW surface up at 15-20kt overnight. Thus, confidence in the LLWS is low.

A strong cold front will bring a period showers and possibly a few thunderstorms after 10z/Thursday morning in the NW, and during the mid to late morning into the afternoon east. Sub-VFR conditions and gusty/shifting winds are expected Thursday. VFR returns Fri into Sat. Increasing moisture return may bring a return to sub-VFR conditions and rain chances on Sunday.

CLIMATE

Record High Temperatures:

March 11: KGSO: 86/1967 KRDU: 85/1925 KFAY: 87/1925

Record High Minimum Temperatures:

March 11: KGSO: 62/2016 KRDU: 63/2016 KFAY: 63/2016

RAH WATCHES/WARNINGS/ADVISORIES

None.