Grayson, KY Weather

What Has Changed

A Frost Advisory is in effect until 9 AM this morning for portions of the central and northern lowlands of WV. Otherwise, the forecast generally remains consistent with the prior cycle, with the one exception being a slight reduction of low temperatures throughout the rest of 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 will continue to provide dry weather throughout the entirety of this forecast period (through Tuesday), as it continues to remain entrenched across the NE/SE CONUS. Near seasonable daytime temperatures are expected throughout the period amid near wall-to-wall sunshine. A weak and dry backdoor cold front will attempt to drop southward through the area on Thursday, potentially resulting in daytime highs a few degrees cooler Thursday/Friday, before a gradual warming trend begins on Saturday, with highs perhaps reaching into the low 70s on Monday across the lowlands (~ 5 degrees above normal).

Soundings continue to prog a very dry layer at ~H850, which will continue to translate down to the surface to an extent during the afternoons with diurnal mixing. Have continued the trend of lowering afternoon dew points from central guidance each afternoon, with minimum relative humidity values generally in the mid 20s and 30s, although lower remains possible in some locations, as fine fuels continue to dry out. Surface flow will however remain quite light, with occasional breezes of 10 mph or greater confined to mainly the mountains.

The persistent 'arid' low/mid levels across the region will continue to facilitate very efficient radiational cooling going forward given clear skies and generally light H925 flow. With this in mind, maintained the trend of undercutting overnight temperatures from that of central guidance through Saturday morning. A Frost Advisory remains in effect until 9 AM this morning across portions of the central/northern lowlands of WV, where temperatures are expected to dip into the low/mid 30s in the valleys away from lakes and rivers. Patchy frost remains possible across the rest of the lowlands where the growing season remains active, but should be more isolated and primarily confined to the typical cold spots. Additional frost potential is expected tonight and the following nights continuing into the weekend under this persistence pattern, with fairly widespread lows in the 30s generally expected most nights. No new frost headlines will be issued at this time for tonight, giving day/evening shift a chance to re-evaluate the potential need for a Frost Advisory tonight based on 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 Thursday) amid 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/HTS/PKB. 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 Thursday morning.

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

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

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.