textproduct: Raleigh

WHAT HAS CHANGED

As of 250 PM Wednesday...

* Marginal risk (level 1 of 5) introduced across southern half of the forecast area for damaging wind potential Thursday

KEY MESSAGES

As of 250 PM Wednesday...

1) A strong cold front will bring widespread showers Thursday, with the possibility of a few strong to severe thunderstorms.

2) There will be a drastic change in temperatures between Wednesday afternoon and Friday morning.

3) A second cold front will bring showers Sunday night into Monday, with another chance for thunderstorms.

DISCUSSION

As of 250 PM Wednesday...

KEY MESSAGE 1... A strong cold front will bring widespread showers Thursday, with the possibility of a few strong to severe thunderstorms.

Low pressure is currently near the Great Lakes and will continue to move northeast along the United States/Canada border over the next 48 hours. The cold front that extends to the south of the low will sweep across North Carolina late tonight into Thursday. Showers are likely to begin in the Triad for the morning commute, while moving into the Triangle towards the end of the morning commute and reaching the I-95 corridor by noon. Although not a drought-buster, it should bring about half an inch of rainfall to all locations. Considering the primary period for rainfall will be in the morning and early afternoon, this is not ideal for the development of widespread thunderstorm activity. With the bulk of the precipitation occurring behind the front and falling temperatures through the day, this will likely require elevated instability to generate thunderstorms. However, effective shear will increase through the day, particularly to the south and east of the Triangle. Similarly, instability will be highest south and east of the Triangle. With the Wednesday afternoon update to the Thursday convective outlook, SPC has introduced a marginal (level 1 of 5) risk generally across the southern half of the forecast area, with the primary threat being damaging winds.

KEY MESSAGE 2... There will be a drastic change in temperatures between Wednesday afternoon and Friday morning.

Highs today are forecast to range from the mid 80s in the northwest to 90 degrees in the southeast. 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) and Fayetteville (March 17, 1945). Calendar day highs for Thursday are likely to occur at midnight (in the low to mid 70s) with temperatures falling through the entire calendar day all the way to dawn Friday morning. Friday morning lows are expected to be within a few degrees on either side of the freezing mark, resulting in a 60 degree drop in temperatures in 36 hours.

KEY MESSAGE 3... A second cold front will bring showers Sunday night into Monday, with another chance for thunderstorms.

A chance of showers will develop as early as Sunday afternoon with southerly flow bringing Gulf and Atlantic moisture into the region. However, the bulk of the rain is not expected to arrive until Monday with the arrival of a cold front, with another low pressure system that is expected to move northeast across the Great Lakes and follow the United States/Canada border. Considering this is five days out, it's hard to have high confidence in any severe weather potential, although the SPC extended outlook states that 'any severe potential along the East Coast appears low at this time as the primary forcing for ascent lags behind the surface front.' AI convective forecasts do show a slight risk potential across eastern North Carolina on Monday, but these forecasts usually depict the ceiling for forecast possibilities.

AVIATION /00Z THURSDAY THROUGH MONDAY/

As of 745 PM Wednesday...

VFR conditions are expected to start the TAF period. South to southwest winds continue to prevail across the terminals this evening and this is expected to continue prior to a cold frontal passage Thursday morning. Once the front moves through, gusts will remain, but switch to be out of the northwest between 25 and 30 kt, with an infrequent gust to 35 kt certainly possible as well. With the front approaching, restrictions with showers will promote MVFR conditions. The heaviest period of showers looks to move through between 14 and 21z, earliest in the west at GSO/INT and latest at RWI in the east. Associated with these heavier pockets of rain will be the potential for IFR and perhaps brief LIFR. Instability may favor a low-end storm threat, most favored at FAY, where a TEMPO for TSRA was introduced. VFR should return by the tail end of the TAF period, though gusts should continue from the NW before diminishing Thu night.

VFR returns Fri into Sat. Increasing moisture return followed by another cold front will bring a return to sub-VFR conditions and showers on Sunday and Monday.

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.