textproduct: Charleston

WHAT HAS CHANGED

00Z Aviation Forecast Discussion update.

KEY MESSAGES

- 1) Warming trend continues with isolated showers and storms through midweek increasing late in the week due to cold frontal passage.

- 2) Drier weather with more seasonable temperatures follow the cold front for the weekend and into the new work week.

DISCUSSION

KEY MESSAGE 1...

Surface high pressure across the area will provide mostly dry conditions to the region. There will be some slight chances for diurnal showers and thunderstorms which will be isolated in nature for Today and Wednesday although this should be confined to the northern tiers of our County Warning Area. According to the National Blend of Models Wednesday looks to be dry although one cannot rule out a diurnal shower or thunderstorm activity during the maximum daytime heating as the area gets to anomalously high temperatures for this time of year. Confidence on PoPs is low as central guidance is having a hard time dealing with this type of solution and setup with a dirty high pressure system influencing the area. Had to increase PoPs for Thursday and thunderstorm coverage as guidance did not support much activity as well and we are in a slight risk for Severe thunderstorms for much of the area.

Also, the moisture flux from the Great Lakes driving around the periphery of the high pressure system will traverse into the area which will bring higher dew points, therefore humid conditions along with the heat will be the main theme through Thursday and even into Friday. A convective complex is forecast by convective allowing models for Wednesday morning and afternoon, however timing and position of this feature is not certain and could very well touch our northern most parts of the area. SPC has a marginal threat for severe thunderstorms just touching our northern border. Guidance did not include much in the away of PoPs but since confidence is low decided to accept guidance this time around due to model uncertainty.

Elsewhere will be mainly dry and, for much of the lowlands, hot enough to maintain the Heat Advisories through at least Wednesday. For Thursday, advisories or warnings will likely be needed as heat index values reach the 105 degree threshold of a warning. Will continue to monitor and issue as needed. The highest values will be centered across the Huntington Tri-state and Charleston Metro areas. Boundary layer temperatures will support these high temperatures until Friday when cold frontal passage is forecast later in the day.

KEY MESSAGE 2...

For Thursday, shower potential rises as a cold front swings down from the south and promotes shower and thunderstorm activity out ahead of the frontal boundary. SPC has us in a slight risk for possible severe thunderstorm potential with modest shear and instability to support this as well as anomalously high temperatures that will add to the unstable environment. For Friday, the cold frontal boundary slides through promoting more chances for thunderstorm activity as well as severe potential as SPC has us in a slight risk (15% probability) for the afternoon and evening. Models have the aforementioned feature slowing down, therefore it will likely affect Saturday as well during the morning and afternoon hours.

Models have surface high pressure building in behind the front which should suppress much in the way of shower or thunderstorm potential the rest of Saturday and Sunday. Drier weather is expected and cooler weather will break the warming trend for the end of the weekend. The area will likely become settled after Saturday as mid and upper level heights build slowly behind the aforementioned cold frontal boundary into Sunday. Mid to upper level high pressure will reinforce settled weather going into the new work week.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

Patchy fog is expected to develop under calm to light flow and mostly clear skies late tonight into early Wednesday. MVFR or worse conditions are likely to occur wherever fog develops. Once fog dissipates, area wide VFR should return for the remainder of the TAF period.

Winds will be light and generally out of the southwest during the day Wednesday.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z THURSDAY... FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: Extent of fog 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.

UTC 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06 EDT 1HRLY 15 16 17 18 19 20 21 22 23 00 01 02 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 M M 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 00Z THURSDAY... IFR conditions are possible with patchy river valley fog Thursday morning. IFR conditions and strong wind gusts also possible in thunderstorms late Thursday through Friday.

RLX WATCHES/WARNINGS/ADVISORIES

WV...Heat Advisory until 8 PM EDT Wednesday for WVZ005>010-013>019- 026>029. OH...Heat Advisory until 8 PM EDT Wednesday for OHZ066-067-075-076- 083>087. KY...Heat Advisory until 8 PM EDT Wednesday for KYZ101>103-105. VA...None.