textproduct: Raleigh

WHAT HAS CHANGED

As of 1240 AM Thursday...

* Only a chance of light rain showers tonight and early Friday, mainly in the south and east. * Confidence in a significant weekend winter storm continues to increase. * Continued high confidence in bitterly cold temperatures from early Saturday through early next week.

KEY MESSAGES

As of 1240 AM Thursday...

1) Moderating temperatures today into Friday ahead of the arctic front Friday night. Only a chance of light showers night into Friday. Time to prepare for the winter storm expected this weekend.

2) A Winter Storm Watch has been issued for the Piedmont and portions of the central and northern Coastal Plain. This is due to confidence increasing in widespread snow, sleet, and freezing rain Saturday into Sunday.

3) Extremely cold temperatures and dry conditions are expected behind the front early next week.

DISCUSSION

As of 1240 AM Thursday...

KEY MESSAGE 1... Moderating temperatures today into Friday ahead of the arctic front Friday night. Only a chance of light showers tonight into Friday. The amounts will be light, only less than 0.10 and higher probabilities in the SE. .

Highs today will return to the 50s. Lows tonight will be in the mid 30s to around 40.

KEY MESSAGE 2... A Winter Storm Watch has been issued for the Piedmont and portions of the central and northern Coastal Plain. This is due to confidence increasing in widespread snow, sleet, and freezing rain Saturday into Sunday.

Confidence is increasing in a Miller B low track bringing widespread snow, sleet, and freezing rain to the region. All of the 12Z LREF clusters are showing precipitation across the region this weekend. With very cold high pressure moving into the region after the passage of an Arctic cold front, wintry precipitation types will be likely to occur. During the day on Saturday, an inverted trough will set up over the southeast US, with a CAD setup over central NC due to the high pressure funneling cold air into the region. By Sunday morning, low pressure will move northeast out of the Gulf, eventually dissipating over the Appalachian mountains. At the same time, a low will form off the coast of the Carolinas and move north, setting up the Miller B pattern.

During this type of pattern, multiple precipitation types are likely. While we will be cold at the surface, sleet and freezing rain are looking increasingly likely as warming trends are being shown at around 850mb. The latest cluster analysis from the 12Z LREF shows that the majority of the solutions indicate a warm nose making its way well inland, perhaps as far west as the NW Piedmont. The thickness and strength of this warm layer will determine what exact precipitation type will occur at any given location. While many locations may start off seeing snow on Saturday morning, a changeover from snow to sleet and/or freezing rain will remain possible everywhere Saturday afternoon through the day on Sunday. Precipitation is expected to move out of the region Monday morning. Regardless of type, whatever does fall/accrue could be significant and may have lingering effects well into the next work week. Thus, a Winter Storm Watch has been issued for Saturday afternoon through Monday afternoon for the Piedmont and portions of the central and northern Coastal Plain.

KEY MESSAGE 3... Extremely cold temperatures and dry conditions are expected behind the front early next week.

Extremely cold temperatures and dry weather are expected behind the exiting winter storm early next week. Arctic surface high pressure will build into the area early next week, then settle over the region. This will yield low temps bottoming out in the single digits to low teens by Tuesday morning with wind chill values near zero to the single digits. High temperatures are expected to be in the 30s early to mid next week as well. Thus, much below normal temperatures are expected for an extended time early to mid next week and a Cold Weather Advisory or Extreme Cold Watch and/or Warning may be needed during this time frame.

AVIATION /06Z THURSDAY THROUGH MONDAY/

As of 1240 AM Thursday...

There is high confidence in VFR through the 24-hour TAF period. Ceilings will lower somewhat to around 5 to 8 kft with an approaching weak cold front, but remain VFR. Winds will generally remain out of the WSW early then becoming WNW this morning ahead of a cold front that will push through today.

Outlook: A band of light rain may lead to sub-VFR conditions later tonight into Fri, with the highest probability at FAY/RWI. This weekend, confidence continues to increase in a potential winter storm, which will likely bring wintry precipitation and associated sub-VFR conditions late Sat and Sun, before VFR conditions return early next week.

CLIMATE

Record Low Maximum Temperatures:

January 25: KGSO: 23/1940 KRDU: 28/2013 KFAY: 30/2013

Record Low Temperatures:

January 27: KRDU: 8/1940 KFAY: 11/1940

RAH WATCHES/WARNINGS/ADVISORIES

Winter Storm Watch from Saturday afternoon through Monday afternoon for NCZ007>011-021>028-038>043-073>077-083-084.