Tornado, WV Weather

What Has Changed

A Frost Advisory is in effect until 9 AM this morning for much of southeast Ohio and the central/northern lowlands of WV, with a SPS elsewhere where the growing season is still active. Otherwise, the forecast generally remains consistent with the prior cycle, with the one exception being the reduction of low temperatures throughout the work week, and the inclusion of patchy frost in some areas. Updated 12Z Aviation Discussion.

Key Messages

1) High pressure ruling the roost through the weekend will continue to provide extended dry weather, with near seasonable daytime temperatures, while chilly overnights with patchy frost potential and river valley steam fog.

Discussion

KEY MESSAGE 1...

Sprawling surface high pressure anchored just north of the Great Lakes has resulted in another morning of clear skies amid a very dry lower to middle atmosphere. In fact, 00Z regional RAOBs resemble something more typical of that seen across the high plains than the central Appalachians. This has allowed temperatures once again to quickly fall into the 30s and low 40s across much of the area, amid some developing river valley steam fog along the Ohio River and points south. Expect a slow increase in fog coverage through dawn, quite similar to that of yesterday, perhaps slightly more widespread given current trends, with locally dense fog expected in the 'typical' areas. Lows this morning will range from the mid 20s across the mountain valley cold spots, with 30s expected most elsewhere. A Frost Advisory remains in effect until 9 AM this morning across much of southeast Ohio and the central/northern lowlands of WV. A SPS is in effect for our remaining zones where the growing season is still active, but overall, coverage is expected to be much more patchy here given more river valley fog and dew points that didn't mix down as low Monday afternoon compared to locations further north.

A persistence pattern remains in place over the next few days as high pressure prevails across the region. Soundings continue to depict a very dry layer near H850, which will likely mix down to an extent during the afternoons, with dew point drops Monday afternoon nearing a very impressive 15 degrees is some locations. Given such, have lowered afternoon dew points over the next few days, with minimum afternoon RH values generally in the 20s/30s, but amid very light surface flow. Near seasonable daytime temperatures are expected, with mid 60s to 70 or so across the lowlands amid mostly sunny skies. A weak and dry backdoor cold front will attempt to slide through the region sometime on Thursday, potentially resulting in temperatures a few degrees cooler through Saturday. Return downsloping flow will result in a gradual warming trend on Sunday/Monday.

The very dry low/mid levels will continue to facilitate efficient radiational cooling throughout the work week. Given such, have continued the trend of lowering overnight temperatures from central guidance a fair amount towards COOP MOS, with fairly widespread low temperatures in the 30s expected through Thursday morning. Patchy frost will once again be possible tonight, and perhaps more so Wednesday night. Given anticipated lower coverage tonight, will not issue any headlines at this point and will allow day/evening shift to re-evaluate given afternoon and evening T/Td trends.

Overnight and early morning river valley steam fog is expected to persist throughout the work week and weekend given a continued large air / water temperature difference, with fog locally dense in spots.

Aviation

Dry weather continues through this TAF period (until 12Z Wednesday) amid mainly clear skies. The only aviation concern during this period is with river valley steam fog this morning, and again tonight, with IFR or worse restrictions expected at CRW/EKN/PKB, and potentially at HTS. Fog this morning will slowly lift / scatter from ~ 12-1400Z, with widespread VFR thereafter. River valley fog will then begin developing once again at ~6-9Z Wednesday morning.

Calm flow this morning will give way to very light NNE/N surface flow during the day today. Flow goes calm after sunset.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY...

FORECAST CONFIDENCE: Medium with fog, otherwise high.

ALTERNATE SCENARIOS: Restrictions with fog this morning and tonight may vary from the forecast.

EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.