textproduct: Raleigh

WHAT HAS CHANGED

As of 215 PM Friday...

* Increasing confidence in a period of rain from early Sun morning into Sun night, with brisk and gusty winds expected Sun/Sun night.

KEY MESSAGES

As of 230 PM Friday...

1) Record warmth is possible to the south this afternoon with winter- like temperatures across the north.

2) Chance of rain Sat, highest from the Triangle S and E, then rain is likely to definite areawide late Sat night through Sun evening, with brisk/gusty winds Sun/Sun night. Chance of a light coating of wet snow in the far NE Sun night.

3) A rollercoaster in temperatures is expected next week. Temperatures will be below normal early in the week, turning above normal on Wednesday and Thursday, then cooling back down on Friday behind a cold front that may provide some rain to the area.

DISCUSSION

As of 230 PM Friday...

KEY MESSAGE 1... Record warmth is possible to the south this afternoon with winter-like temperatures across the north.

As of 12pm, the temperature in Henderson and Roanoke Rapids was only 45 degrees, while Maxton and Fayetteville were both 79 degrees. The cold front in the forecast area is clearly between these two pairs of stations, and a band of showers along the front should bring a round of rain lasting around an hour to the rest of the forecast area. Within a couple hours of the frontal passage, skies are clearing out and temperatures are warming up, with the Triad now into the mid 50s. Another round of gusty wind is expected this afternoon behind the front at all locations, although the gusts would likely be less this afternoon behind the front than they were in advance of the front this morning.

KEY MESSAGE 2... Chance of rain Sat, highest from the Triangle S and E, then rain is likely to definite areawide late Sat night through Sun evening, with brisk/gusty winds Sun/Sun night. Chance of a light coating of wet snow in the far NE Sun night.

Overview: A mid level shortwave trough digging over the High Plains early Sat will dig and amplify over the Great Lakes/Ohio Valley into the Mid South through Sat night, before taking on a negative tilt and deepening further as it swings through NC and closes off a low off the Mid Atlantic coast Sun through Sun night. At the surface, today's front will settle just to our S, across N GA, SC, and SE NC, with surface lows tracking E along the front, most notably late Sat through early Sun, culminating in what could be a bombing low off the N Outer Banks, VA Tidewater, and S Delmarva Sun night.

Lift/precip chances: Mostly light and elevated moist isentropic upglide Sat will bring light rain chances through the evening, with the highest chances S and SE of the Triangle where low level moisture including surface dewpoints will be higher, and where SW low level jetting will focus the stronger upglide. As earlier shifts noted, this results in lower confidence in high temps Sat, as more rain further north into the cooler and more stable air will hold down the diurnal temp range, possibly keeping temps down in the low- mid 50s in our far N. Strengthening DPVA and high height falls of 200-250 m Sun into Sun evening will deepen and intensify overall lift over central NC as the cooling aloft raises lapse rates a bit, so the higher rain chances will be early Sun morning through early- mid Sun evening. Confidence is fairly high in rainfall amounts of one-third to one half inch, with isolated higher totals, esp E.

Snow potential: With steepening lapse rates through the column corresponding to the deepening lift and resultant saturation in the mixed phase region aloft, the chance for a brief period of snow near the end of the precip event remains possible in the NE CWA. Ensemble guidance indicates a non-zero but low risk for accumulating snow, likely due to the short duration, warm ground, and expected borderline surface wet bulb temps. But the LREF probability of a tenth of an inch of accumulation (dusting) mainly Sun evening through Sun night is 33%-50% in spots like Henderson, Enfield, Norlina, and Roanoke Rapids. The chance for a quarter inch of snow is about 33% in northern Warren/Halifax counties, and the chance for a half inch there is around 20%. So the highest potential for some briefly slick roads is in this far NE corner and near the VA border. Will continue to monitor trends in duration and amount of snow esp given the warm ground, but overall impacts should be minor.

Wind: As the low strengthens just off the coast of NE NC and SE VA and leads to a quickly tightening MSLP gradient, this along with the increasing surface-based lapse rates fostering the potential mixing- down of stronger winds aloft is likely to result in brisk and gusty winds Sun/Sun night. The confidence in these stronger winds is high enough such that the official forecast is a lean toward the higher NBM percentiles, and even this may not be strong enough if some ensemble members and deterministic models are correct in showing mean BL winds of 30-40 kts late Sun.

KEY MESSAGE 3... A rollercoaster in temperatures is expected next week. Temperatures will be below normal early in the week, turning above normal on Wednesday and Thursday, then cooling back down on Friday behind a cold front that may provide some rain to the area.

Strong NW flow on the backside of the departing coastal low will result in cool conditions early next week across central NC. Monday's high temperatures will only reach the lower-40s to upper- 40s, which is 10 to 15 degrees below normal. Momentum transfer from GFS BUFKIT soundings indicates wind gusts of 25-35 mph will be possible during the day, so it will be quite brisk with apparent temperatures largely staying in the 30s. Lows will drop into the mid- to-upper-20s on Monday night, and while the pressure gradient will start to relax and winds will lessen, some wind chills in the teens will still be possible. Temperatures will moderate a bit on Tuesday with highs in the mid-40s to lower-50s and lows in the lower-to-mid- 30s. By Wednesday, the surface high will push east to around Bermuda which will turn the low-level flow SW and aid a rebound in temperatures to back above normal. Forecast highs are upper-50s to lower-60s, with lower-to-mid-60s on Thursday.

As a shortwave becomes negatively tilted over the Lower Great Lakes and Northeast US and induces a surface low, a cold front will move through central NC sometime late Thursday or early Friday. Some rain is possible along and ahead of the front, but there is still plenty of uncertainty on timing and amounts, with the GFS and CMC much slower compared to the ECMWF. Regardless of which model, ensemble probabilities of rainfall exceeding an inch are virtually non- existent, with a quarter to half inch appearing more likely. There is also a lack of instability, and the best upper forcing goes well to our north. So heavy rain that puts a significant dent in the ongoing drought appears unlikely at this time. Temperatures will drop back to near or possibly below normal on Friday behind the front.

AVIATION /18Z FRIDAY THROUGH TUESDAY/

As of 1210 PM Friday...

TAF period: High confidence in VFR conditions through much of the TAF period. Cannot rule out some brief lingering restrictions at RWI/FAY with the line of showers along the passing cold front, but within a few hours of the frontal passage, skies should become clear. Wind gusts out of the west-southwest are expected up to 30 kt, but the gusts will likely be slightly lower this afternoon than the gusts ahead of the front that occurred this morning. Expect light wind out of the west this evening with increasing high clouds, then a wave of low pressure along the front will approach the region late tonight into Saturday. This should bring scattered showers to all sites, with the lowest chances at INT/GSO and the highest chances at FAY (but not enough confidence to go prevailing at this time). If rain moves in to FAY before 18Z Saturday, there could be MVFR ceilings as well.

Outlook: Widespread MVFR/IFR rain is expected at all terminals Saturday night and continuing at RDU/FAY/RWI Sunday morning. As rain comes to an end Sunday afternoon/evening, cannot rule out a few flakes mixing in with rain drops. Dry VFR conditions are then forecast through Wednesday.

CLIMATE

Record High Temperatures:

February 20: KGSO: 74/1922 KRDU: 75/1939 KFAY: 82/2014

Record High Minimum Temperatures:

February 20: KGSO: 56/1939 KRDU: 62/1939 KFAY: 60/1939

RAH WATCHES/WARNINGS/ADVISORIES

None.