textproduct: Raleigh

WHAT HAS CHANGED

As of 248 PM Wednesday...

* Nothing appreciable.

KEY MESSAGES

As of 248 PM Wednesday...

1) Dry fuels combined with lower humidity and near record heat will promote fire weather concerns through the weekend.

2) An early-season heat wave will result in near record high temperatures through Saturday.

3) A late-weekend pattern transition is expected with a cold frontal passage. Low-end rain chances are expected on Sunday, followed by much cooler temperatures early next week.

DISCUSSION

As of 248 PM Wednesday...

KEY MESSAGE 1... Dry fuels combined with lower humidity and near record heat will promote fire weather concerns through the weekend.

The anomalous mid-level ridge will amplify along the eastern seaboard through the end of the week. Associated subsidence over the southeast will promote continued dry conditions at least through Saturday. Precipitation as a percentage of normal over the past 30 days is as low as 5 to 25% for portions of our area worsening the elevated drought conditions. As such, fuels have been anomalously dry for some time.

Deep mixing on Thursday will promote a bit gustier sfc flow upwards of 20 kts or so in the afternoon. PWAT will remain below an inch, and given deep mixing, expect afternoon relative humidity to bottom out in the mid to upper 20s. While the combined expected min RH and max gusts will be sub IFD criteria, the aforementioned fire risk due to anomalously dry fuels has prompted a request for another IFD for our entire CWA on Thursday (to be issued by the evening shift). A few CAMs are hinting at late night isolated showers possibly reaching the western/central Piedmont. However, limited moisture would only allow for trace to maybe a few hundreds of an inch of rain, if any at all.

Winds will be lighter on Friday and Saturday but dry conditions will persist. As such, expect Increased Fire Danger Statements to likely be issued daily until things change significantly.

Light rain will be possible Sunday, but QPF should be generally pretty low. As such, fire weather concerns will likely persist late weekend (isolated lightning on Sunday would be concerning) into early next week.

Key Message 2: An early-season heat wave is expected to bring near- record high temperatures through Saturday.

A strong and persistent area of subtropical high pressure will remain over the Southeast U.S. through most of this period, with only a brief interruption from a weak, dry disturbance on Friday. At the surface, a Bermuda High will promote warm southwesterly winds into central North Carolina.

Atmospheric thickness values (1000850 mb) are forecast to be near the 95th percentile for this time of year, supporting unusually warm conditions. Daily high and low temperatures may approach or even break records. Expect afternoon highs mainly in the lower 90s and overnight lows in the lower to mid-60sabout 15 to 20 degrees above normal. Saturday is likely to be the hottest day, with some locations possibly reaching the mid-90s, which would be close to the warmest temperatures ever recorded in April.

Humidity levels should remain relatively manageable, with dew points generally in the lower to mid-50s, and even dipping into the 40s at times, especially in western areas. As a result, heat index values will be slightly lower than the actual air temperatures by a few degrees. Even so, several consecutive days of lower-90s temperatures could pose a risk of heat stress, particularly for sensitive individuals and anyone spending extended time outdoors.

Key Message 3: A shift in the weather pattern is expected late this weekend as a cold front moves through. This will bring a slight chance of rain on Sunday, followed by much cooler temperatures early next week.

A broad upper-level trough will move eastward from the Plains into the eastern United States over the weekend. Its associated cold front is forecast to pass through central North Carolina on Sunday. This could bring a few showers and possibly an isolated thunderstorm. However, current model guidance (including the GFS and ECMWF) suggests the front will move through relatively early in the day, limiting atmospheric instability. Forecast instability values remain low, with only a few hundred J/kg of CAPE expected. In addition, the strongest lift and deepest moisture are expected to stay north of the area, which should keep rainfall amounts light. Ensemble averages indicate totals of around a tenth of an inch or less, meaning little to no improvement in ongoing drought conditions.

Behind the front, a noticeably cooler air mass will settle in for Monday and Tuesday. Temperatures are expected to fall below normal, with daytime highs mainly in the upper 60s to lower 70s and overnight lows dropping into the 40s (some 30s are possible Tuesday morning according to some of the latest guidance in the Piedmont).

AVIATION /18Z WEDNESDAY THROUGH MONDAY

As of 115 PM Wednesday...

VFR conditions will persist through the 24 hr TAF period with light swly sfc flow diminishing overnight. Sswly sfc flow will pick back up on Thursday gusting upwards of 15 to 20 kts in the afternoon.

Outlook: Sub-tropical high pressure will favor warm, dry, and VFR conditions in cntl NC through Sat. Light, probably VFR rain will be possible along and behind a cold front that will move across cntl NC early Sunday.

CLIMATE

All-Time Records for April

KGSO: 95 on 4/28/1915 KRDU: 95 on 4/23/1980 and 4/28/1896 KFAY: 96 on 4/12/1930

Record High Temperatures:

April 15: KGSO: 90/2006 KRDU: 92/1941 KFAY: 95/2006

April 16: KGSO: 88/2002 KRDU: 92/1941 KFAY: 94/2006

April 17: KGSO: 90/1967 KRDU: 93/1896 KFAY: 92/1941

April 18: KGSO: 90/1976 KRDU: 95/1896 KFAY: 93/1941

April 19: KFAY: 94/1941

Record High Minimum Temperatures:

April 15: KGSO: 65/2006 KRDU: 64/1993

April 16: KGSO: 66/2006 KRDU: 64/1912 KFAY: 69/1934

April 17: KGSO: 63/2002 KRDU: 67/1896 KFAY: 66/1921

April 18: KGSO: 66/1909 KRDU: 63/1941 KFAY: 67/2002

April 19: KRDU: 67/1896 KFAY: 67/2002

RAH WATCHES/WARNINGS/ADVISORIES

None.