textproduct: Raleigh

WHAT HAS CHANGED

As of 936 AM Sunday...

KEY MESSAGES

As of 333 AM Sunday...

1) A cold front will surge south through the region very late today and this evening. There is a chance of a brief shower with the frontal passage. Winds will be gusty from the NE to 25 mph just behind the front for a few hours.

2) A chilly light rain is expected Monday afternoon through Tuesday morning. Low overcast, light rain/drizzle and miserable mid 30s return.

3) Well-above normal temperatures and near record breaking warmth expected late week into the weekend.

DISCUSSION

As of 333 AM Sunday...

KEY MESSAGE 1... A cold front will surge south through the region very late today and this evening. There is a chance of a brief shower with the frontal passage. Winds will be gusty from the NE to 25 mph just behind the front for a few hours.

The fog this morning is expected to be rather localized to low-lying and fog prone areas. It is clear and the winds are light. Radiational cooling will lead to some localized fog, some may be less than 1/4 mile for a few hours. Otherwise, any fog will burn off quickly this morning with plenty of warm sunshine expected this afternoon. Highs will warm quickly and reach the upper 60s NE and well into the 70s elsewhere. The warming will be aided by a drying downslope breeze from the west this afternoon. There may be a brief light shower associated with the backdoor cold front late this afternoon, especially in the north and east.

The backdoor cold front will surge south through the area late this afternoon and this evening. It will be pushed by a 1035+ mb surface high pressure that will be traversing the Great Lakes states east to NY tonight. CAA with the NE flow tonight will send temperatures tumbling back into the upper 30s to lower 40s by daybreak Monday.

KEY MESSAGE 2... A chilly light rain is expected Monday afternoon through Tuesday morning. Low overcast, light rain/drizzle and miserable mid 30s return.

The large and strong (nearly 1040 mb) surface high pressure will be very progressive in moving off the New England coast Monday night. It will extend SW across our Piedmont damming region into Tuesday.

However, the coldest and driest part of the low level air mass will be delivered during the day Monday with the progressive nature of the high. A mid-level disturbance is expected to reach the central Appalachians from the OH Valley early Monday, then weaken as it moves across VA and northern NC Monday afternoon.

Developing isentropic lift a top the shallow sloped low/mid-level frontal boundary is expected to support light stratiform rain over the Mid-Atlantic. The majority of the guidance continues to suggest a general light (0.01 to 0.15) of rainfall during Monday into Monday night (highest to the north). The GFS has been leading the way with a persistent signal of some QPF, with the NAM just catching on. Therefore, POP has come up somewhat from the previous forecasts along with confidence in some light rain.

As for the P-Type, the general model consensus depicts partial thicknesses in the cold nose centered from Roxboro to Greensboro (of 1555+ m in the 850-700 layer and 1300-1310+ in the 1000/850 layer by 00z/Tue. The 1000/850 thicknesses rise into the 1310-1320 by 00z- 06z/Tue, then 1320s Tuesday). Just a bit too warm aloft, and potentially marginal (1300-1305m) for some rain/icing mix - around dusk Monday - but trending warmer overnight -

Referring to the wet bulb zero forecasts, not surprisingly most guidance with a few exceptions depict surface wet bulb temperatures 33-35 north and 35-38 south during the critical time of late Monday and Monday night, when we should be precipitating lightly.

All this data essentially supports rain with a low probability of some very light freezing rain mix near the VA border area early Monday night. And, that really is if the wet bulbs can fall to below 32, which if it occurs should be very limited to our far north and to the Monday night period. It should be pointed out that road and ground temperatures will rise with the heat today (and will likely remain well above freezing during the light rain and chilly temperatures Monday night.

Thus, the most likely scenario for this event will likely be periods of light rain and drizzle with temperatures falling into the mid 30s north and lower 40s south by late Monday, bottoming out 33 to 40 north to south Monday night. QPF generally 0.10 to 0.25 north of the Triad to less only a few hundredths south. No hazardous weather or impacts to travel expected.

Worst-case scenario (10% chance): The surface wet bulb temperatures fall into the 31-32 range over the far northern Piedmont Monday night with the light rain, allowing for some very light icing (freezing rain/drizzle) on elevated surfaces A slick bridge or overpass could then result.

KEY MESSAGE 3... Well-above normal temperatures and near record breaking warmth expected late week into the weekend.

An unseasonably strong and deep ridge is expected to develop over the East Coast by midweek, but will become more amplified as a trough dives south through the Four Corners Region late week into the weekend. The mid/upper level pattern along with a deep layer of unseasonably warm temperatures in the lowest 500mb of the troposphere will favor well above normal temperatures to near record breaking warmth Fri into the weekend. During this time, highs eclipsing 80 degrees become likely, especially from the Triangle south and east. Temperatures in the mid 70s to around 80 would likely result in minor heat-related impacts primarily to individuals extremely sensitive to heat and without cooling/hydration. Please see climate section below for daily records.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

As of 1236 PM Sunday...

VFR conditions will persist through much of the early 24 HR TAF period. Near sunset, scattered showers along a backdoor cold front may briefly hit KRWI/KRDU around ~23 to 03Z. A crack of thunder may accompany these showers, but overall they should not be overly impactful. Immediately behind the backdoor cold front, nely sfc gusts of 20 to 25 kts will be possible, persisting through sunrise. Additionally, immediately following the front expect MVFR ceilings to spread across western/southern areas before filling in at all airports Monday morning.

A low pressure system will bring mostly rain to central NC Monday into Tuesday morning. At the onset of precipitation, a brief period of sleet may mix in with cold rain at KINT/KGSO. Confidence isn't entirely high wrt to mixed ptype, but wanted to at least mention the potential for ice pellets from ~15 to 18Z.

Outlook: Cold rain and further socked in conditions (lowered ceilings and perhaps some fog/reduced visbys) will develop Monday night into Tuesday. Conditions should improve on Tuesday and persist through end of the week. Some showers and storms may be possible on Friday.

CLIMATE

Record High Temperatures:

March 6: KGSO: 78/2022 KRDU: 82/1967 KFAY: 86/1918

Record High Minimum Temperatures:

March 6: KGSO: 64/1967 KRDU: 64/1967 KFAY: 65/1961

RAH WATCHES/WARNINGS/ADVISORIES