textproduct: Raleigh

WHAT HAS CHANGED

As of 230 AM Wednesday...

* Rain chances have decreased on Friday and generally remained the same for Saturday and Sunday.

KEY MESSAGES

As of 230 AM Wednesday...

1) Despite multi-layered cloudiness and somewhat shallow boundary layer mixing, today will be unseasonably mild and windy.

2) While uncertainty remains over the weekend, best rain chances appear focused Saturday into Sunday.

3) Temperatures warmest on Fri, falling below normal next week in the 40s. Brisk winds possible Sun and Mon.

DISCUSSION

As of 230 AM Wednesday...

KEY MESSAGE 1...Despite multi-layered cloudiness and somewhat shallow boundary layer mixing, today will be unseasonably mild and windy.

Latest sfc analysis depicted sswly flow across central NC along the western ridge of the offshore sfc high. Despite multi-layered cloudiness expected today, sswly gusts of 20 to 25 kts are likely later this morning and afternoon. Sites further east may see occasional gusts of 30 to 35 kts later this afternoon. Gustiness should largely subside by the early evening. Given the strong sswly flow, temperatures today should be quite mild in the upper 60s to around 70 in the south.

Expect cloudiness to persist into the overnight hours as a weak vorticity lobe shifts south across the mid-Atlantic. This feature may generate light rain across the north later tonight, but generally trace to maybe a few hundreds of an inch of QPF is expected through 12Z Thursday.

KEY MESSAGE 2...While uncertainty remains over the weekend, best rain chances appear focused Saturday into Sunday.

A cold front is still forecast to move through the region between Fri night and Sat morning. As the front settles along and south of the area Sat through Sun, model and ensemble guidance continues to favor the development of a trough at mid-levels that tracks from the Central Plains late Sat into the Carolinas and SE US late Sat into Sun, before tracking east of the region early next week Mon.

It is difficult to say how much rain we may get on Fri ahead of the cold front. Some guidance is fairly dry, while other ensembles and operational models are wetter. At best, a tenth of an inch or less is possible. The pattern does not really support a wet passage with the ridge in place. The drier pattern seems favored by the AI-GFS as well. Overall, lowered PoPs for Friday as more models/ensembles trended on the drier side.

The better chance of rain will likely come Sat into midday Sun with the aforementioned trough. The majority of ensemble cluster solutions show the highest rain chances during this time period. There remain some timing differences, mainly driven by the timing and orientation of the trough. The majority of solutions also bring precipitation to an end by early afternoon Sun, while one outlier scenario starts rain later Sat night and continues it through most of Sun, before exiting the region Sun evening. The EC-AIFS and AI- GFS appear to also support the earlier end to the rain by midday Sun. The guidance continues to support a surface low tracking across the Carolinas late Sat into Sun, before exiting off the Mid-Atlantic coast Sun night. Dry conditions should prevail Mon and Tue.

Given the continued uncertainty, there still is a decent bit of spread in expected rainfall totals. The low end amounts range from a quarter to one half inch of rain, while the higher end amounts range from 0.75 to 1.25 inches. We would expect better agreement as we get closer to the event.

KEY MESSAGE 3...Temperatures warmest on Fri, falling below normal next week in the 40s. Brisk winds possible Sun and Mon.

Our warmest temperatures are still expected to be on Fri, in fact well above normal of about 20 degrees, despite clouds and a chance of showers. Highs could get into the 70s most areas, and maybe briefly 80 degrees across portions of the Sandhills and southern Coastal Plain. We still expect a gradual downward trend in forecast highs Sat through Tue, with the coldest temperatures expected behind a strong cold front by Mon and Tue with highs in the mid/upper 40s. Low temperatures Mon/Tues night under cold high pressure could easily dip into the 20s for most locations. Depending on the pattern, brisk WNW winds are possible Sun and Mon afternoon, with gusts possibly over 30 mph. Forecast guidance shows a rather tight pressure gradient coupled to strong cold advection.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

As of 1251 AM Wednesday...

06Z Update: VFR conditions persist this morning while multi-layered mid to high level cloudiness spills across central NC. Think we could still see some visby restrictions at KRWI between now and ~10Z, but perhaps not as pessimistic as previous forecasts. Otherwise, expect MVFR clouds to develop and linger across the Piedmont sometime after sunrise and into the mid afternoon time period. Otherwise, the previous discussion below remains valid at this time.

Will likely need to add some MVFR/IFR ceilings that looks to re- develop tonight into Thursday morning in the next TAF update. Additionally, some very light rain may be possible from 6-12Z across northern terminals.

Previous discussion:

While a chance of radiation fog will exist at RWI due to local effects tonight, areas of SCT/BKN MVFR cloud-layer, to possibly IFR ones at FAY, RWI and INT, are expected to overspread cntl NC Wed morning, as will a 40-45 kt swly low-level jet and related risk of low-level wind shear. MVFR ceilings may linger into the afternoon over the Piedmont on Wed, while they will likely scatter to VFR more quickly at FAY and RWI. Swly surface winds will also strengthen and become strongly gusty through the day Wed, particularly in areas where scattering and deeper mixing materialize most quickly (ie. FAY and RWI).

Outlook: Flight restrictions and rain will accompany a deepening area of low pressure across the region this weekend.

RAH WATCHES/WARNINGS/ADVISORIES

None.

CLIMATE

Record High Temperatures:

February 19: KGSO: 74/1939 KRDU: 76/1939

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

Record High Minimum Temperatures:

February 18: KGSO: 54/1981

February 19: KGSO: 55/1961 KRDU: 62/1938 KFAY: 62/1938

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