textproduct: Wilmington

WHAT HAS CHANGED

Increased chances and amounts for snow, with some wintry mix possible, for Monday morning.

KEY MESSAGES

1) Mixed wintry precipitation expected Monday morning, with accumulating snow for some locations.

2) Warmer and wetter conditions expected from Tuesday through the rest of the week.

DISCUSSION

KEY MESSAGE 1) Mixed wintry precipitation expected Monday morning, with accumulating snow for some locations.

Light precipitation will move out of the area early this morning, as surface high pressure settles into the Great Lakes. Persistent northeasterly flow today will keep conditions dry, but also keep temperatures quite a bit cooler than on Saturday. By tonight into early Monday morning, the continued cold advection will help temperatures drop below freezing for the entire ILN forecast area.

As a shortwave moves east early Monday morning, precipitation is expected to develop and spread into the region. Models have been oscillating significantly on the behavior of this system, which is keeping forecast confidence on the lower end of the scale. While the trend was weaker and further south a day ago, most of the 00Z guidance has come in with a slightly more robust solution, particularly for the southern half of the ILN forecast area.

The main story is that it now appears a little more likely that a swath of wintry precipitation will work its way across the forecast area Monday morning, with up to an inch of snow for a decent part of the area, and some lower-probability potential that banding could produce up to two inches in isolated locations. In addition to this, some mix with sleet or freezing rain also appears possible. The surface will remain locked in ENE flow, but at 925mb-850mb, some southerly flow will bring overrunning theta-e advection. Model soundings look favorable for at least a brief period of sleet or freezing rain to occur. Confidence in where exactly the mix of precipitation types could set up is quite low, but has been included in the forecast for roughly the southern half of the ILN forecast area.

The main impact from this setup will be for some slushy snow or very minor ice accumulations during the Monday morning commute.

Eventually, any remaining precipitation Monday late morning / early afternoon will probably change to rain as temperatures warm, although it also appears possible that surface temps will not warm as fast as previously expected. If that occurs, some light snow or mixed precipitation could continue into the early afternoon hours.

KEY MESSAGE 2) Warmer and wetter conditions expected from Tuesday through the rest of the week.

A pronounced shift in the large-scale weather pattern is expected to begin on Tuesday. On the western periphery of the Bermuda high, deep-layer southerly / southwesterly flow will become established over the southeastern CONUS. A significant feed of warmth and moisture is expected to develop from the Gulf through the deep south, the lower and middle Mississippi Valley, and into the Tennessee and Ohio valley regions. For the ILN CWA, boundary layer flow is expected to switch to southerly at some point on Tuesday, and then more robustly in the warm sector by Wednesday. This theta-e advection will mark the start of both a warming and moistening trend. Max temps in the 50s to lower 60s are expected Tuesday, warming each day and getting into the lower to mid 70s by Friday.

On the periphery of the zone of higher theta-e, repeated rounds of precipitation are expected to develop. Initially on Tuesday, precipitation will be associated with the warm front moving north through the area. Precipitation chances later in the week will be determined by the timing of additional waves moving east / northeast across Mississippi Valley region and into the Ohio Valley and Great Lakes. Some embedded areas of heavy rain, and certainly some convection, will occur at times. From a synoptic pattern standpoint, this is a setup that provides the potential for heavy rain and possible flooding -- focused to the west and southwest of the ILN CWA, but extending into the ILN CWA to some degree as well. Still early to get into specifics about exactly where or when, but the overall potential would increase with additional rounds of precipitation going later in the week or even into next weekend.

Not out of the question that some strong storms could occur at some point next week, more likely in the later part of the week, but still too early to look at when or where that may occur.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

An area of MVFR stratocumulus clouds is moving south into the area this morning. A period of MVFR conditions is expected at the TAF sites for at least a few hours, but clouds are expected to lift and scatter out by early afternoon, leaving VFR conditions through the rest of the day. Winds will generally be out of the northeast, with some gusts of 15-20 knots this morning, before diminishing somewhat this afternoon.

Early Monday morning, snow will move into the area. This snow is likely to bring MVFR visibilities, and there may be a period of IFR conditions as well, though confidence is not yet high enough to include in the TAFs. Also not in the TAFs yet, but possible, is a brief period of sleet or freezing rain.

OUTLOOK...MVFR/IFR conditions will continue Monday morning, with snow in some locations. Occasional MVFR conditions, perhaps with rain, will then occur at times from later Monday through Thursday.

ILN WATCHES/WARNINGS/ADVISORIES

OH...None. KY...None. IN...None.