Area Forecast Discussion
Issued by NWS Charleston, WV
Issued by NWS Charleston, WV
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485 FXUS61 KRLX 161400 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 1000 AM EDT Mon Sep 16 2024 .SYNOPSIS... Dry weather, and elevated fire danger, continues today under strong high pressure. An area of low pressure off the Atlantic coast brings the chance for beneficial rain mid-week. && .NEAR TERM /THROUGH TONIGHT/... As of 1000 AM Monday... Adjusted down hourly temperatures and dewpoints per latest surface observation trends. Used the 50th percentile dewpoints from the NBM to reflect lowering RHs down into the upper 20s this afternoon. Onset of light precipitation should occur overnight mainly along the eastern mountains. Rest of forecast remains on track. As of 240 AM Monday... Light easterly flow today picking up slightly by the afternoon with occasional gusty conditions expected along the higher terrain. Very dry conditions in the low levels courtesy of high pressure anchored to our north will likely mix down and keep the area dry and relatively cloud free other than mid to high clouds coming in off of the tropical system along the Atlantic coast. The afternoon mixing will drop RH values down into the 20s and 30s across the lowlands with slightly higher values along the mountains, however the mountains will have stronger gustier conditions. With the anticipation of a fairly solid deck of mid to high clouds spreading across from east to west throughout the area by this afternoon will likely suppress some daytime heating, therefore elected to use guidance with lower temperatures keeping temperatures slightly below central guidance which equated to a lot of the area not forecast to reach the 80 degree mark. Areas along and west of the Ohio will likely see higher temperatures due to having the longest time without dense cloud coverage. Slight chances for showers will appear in the forecast for the afternoon across southeastern WV and these chances will continue to spread inward and toward the northwest into the evening, eventually making it all the way across the area by early Tuesday morning. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 350 AM Monday... The remnants of a potentially tropical system bring some much needed rain this period, but uncertainty persists as to the amounts and distribution of the rain, owing to the track of the system, and how much moisture is able to spell over the central Appalachians, and back into the middle Ohio Valley. The system will lumber northwestward across the Carolinas and into the Appalachians before dissipating. This will keep most of the area in downslope flow at least up through the mid levels for most of the time. As such, the highest rainfall amounts will be in the mountains, and along the eastern slopes thereof. Even there, total forecast amounts are in the two thirds of an inch to one inch range, with a half inch or less farther west, even under a quarter of an inc over the middle Ohio valley. The DESI probability for at least a tenth of an inch rainfall, or wetting rain, ranges from around 90 percent in the mountains, to around 50 percent over the middle Ohio Valley. The first band of rain is likely to be rotating into the area from the east first thing Tuesday morning, with additional bands to follow. The rainfall will become less organized with time, with decreasing coverage and amounts. PW values will range from 1.5-1.75 inches much of the time, so rain can be occasionally heavy. However, with such dry antecedent conditions, and little if any instability, hydrology issues are not anticipated. Come Wednesday afternoon, we will likely be able to muster narrow CAPE beneath the swirling mid/upper-level low, so thunderstorms are possible, but will not be organized. The clouds will limit diurnal temperature ranges, with highs near to a little below normal, and lows near to a little above. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 350 AM Monday... Shower coverage will decrease further on Thursday as the mid/upper level system starts to pull away to the east, although afternoon thunderstorms are possible given a little thicker CAPE. Ridging surface and aloft will then allow for a return of mainly dry weather Thursday night through the weekend, although a weak, residual mid/upper-level low may be left behind over the southeastern states, in a Rex block with the mid/upper-level high over the northeastern states. The drier weather will allow diurnal temperature ranges to open up again, with highs climbing back above normal, and lows still near to a little below. Lowland highs will generally be in the mid 80s, with afternoon dew points settling into the 50s. Afternoon relative humidity percentages may settle into the 30s. && .AVIATION /14Z MONDAY THROUGH FRIDAY/... As of 630 AM Monday... For this TAF period expecting VFR to dominate. Flow will be easterly at around 5KT across the area with stronger flow along the mountains particularly at BKW where gusts up to 20KT can be expected during the day. That site will endure some llws this evening temporarily until surface winds pick back up. Mainly just high clouds today spreading across the sky which will become likely overcast by this late afternoon. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z TUESDAY... FORECAST CONFIDENCE: High. ALTERNATE SCENARIOS: None. 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. UTC 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01 EDT 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 12Z TUESDAY... Widespread IFR conditions are not expected at this time. && .FIRE WEATHER... As of 405 AM Monday... Dry weather persists at least through the afternoon. Very dry air aloft will mix down to the surface during daytime mixing hours today. Minimum relative humidity values expected into the 20 to 30 percent range across the lower elevations, with slightly higher values in the higher terrain. Easterly winds will continue to gust to between 15 and 25 mph at times across the ridges. Approaching clouds from the east-southeast may help to mitigate such a rise in afternoon high temperatures today. The next potential chance for rain is Tuesday into Thursday in association with a low pressure system originating in the Atlantic, and then any potential lingering tropical moisture associated with it. Confidence in amount and placement of precipitation is low at this time given model spread. The best chance of beneficial rainfall will be along and east of the higher terrain, but some beneficial rainfall farther west cannot be ruled out. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/JZ NEAR TERM...JZ SHORT TERM...TRM LONG TERM...TRM AVIATION...ARJ/JZ FIRE WEATHER...TRM/JZ