Area Forecast Discussion
Issued by NWS Charleston, WV

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KRLX 240750 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 250 AM EST Fri Feb 24 2017 .SYNOPSIS... Unseasonably warm today. A strong cold front crosses pre-dawn Saturday morning, followed by cooler weather for the weekend. A couple systems next week with precipitation chances. && .NEAR TERM /THROUGH TONIGHT/... As of 245 AM Friday... Have some good operational model agreement with the timing of the cold front tonight that will bring showers and thunderstorms to the CWA, generally after 06Z. Plenty of dynamics with this system, with an increasing low level jet and tightening 500mb height gradient in the trailing upper level low, but thermodynamic parameters lack a bit with dewpoints in the low 50s and no appreciable advection of moisture at 850mb. That said, there should be enough going on, warranting the slight risk in the far western CWA for the Day 1 outlook. Given the time of day, QLCS formation to the west may be on the gradual wane heading into our area during the overnight, but strong flows could also be enough to keep a line of storms going. This is reflected in the outlook and the ending of the slight risk over the far western zones. Prior to the front, could be looking at some all time record highs for February today with low 80s in the forecast. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... As of 310 PM Thursday... Possible severe weather late Fri night into Sat morning... Strong cold front approaches the region late Friday night. Out ahead of the front a line of showers and thunderstorms will be likely, but there is still a bit of uncertainty on how strong this line of convection will be as it enters the Ohio Valley. Although an EML plume pushes over the area, with Mid-level lapse rates maxing out at 8.5C/km by 00Z Saturday, a strong cap will be in place. By the time the front pushes in several hours later, the plume shifts east, but lapse rates remain in the 7 to 7.5C/km range with colder air aloft moving in with the upper trough. Low level moisture is quite limited and CAPE values overnight only are in the 300 to 600 J/kg range. This will certainly be a limiting factor, however the concern for severe weather still remains because of the very strong 0-6km bulk shear of +50 knots out ahead of the front. The strong lapse rates and marginal instability should still be enough to keep an upstream QLCS intact as it crosses our region, however it is likely to weaken considerably as it pushes east. It will be likely that any line of convection will have strong wind gusts with it, and given the strong unidirectional shear it is possible that some damaging winds will be possible. The greatest threat will be in the Ohio Valley and a decreasing threat is expected as the system head east. The front will exit the region later Saturday morning and colder air pushes in behind it. There is potential that with the cold air advection and NW flow behind the front that we see a few upslope snow showers across the mountains. However, moisture is very limited so very little accumulation is expected. High pressure will build in Sunday and snow showers come to an end Sunday morning. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 320 PM Thursday... High pressure will be drifts eastward Sunday night. A southern stream driven system pushes into the area on Monday. GFS us still more robust and a bit earlier with this system than the ECMWF. Due to the uncertainty, I went with a blend of ensemble and operational guidance for this period which gives low chance PoP for now. The next system moves in midweek as a surface low comes out of the Rockies. Current guidance has this system passing to our north and dragging a cold through the region Wednesday night. With decent agreement between the overall guidance, have decided to go with likely PoP even being Day 6 of the forecast. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... As of 1235 AM Friday... VFR dominated forecast ahead of a cold front that will push towards the Ohio River Valley near the end of the forecast period. Ceilings to lower ahead of the system, but should stay well above any restriction thresholds. Expecting the flow to pick up through the period as well out ahead of the aforementioned cold front. Since the wind will exist at the surface, will forego any LLWS in the forecast, but it should be noted that low level wind speeds will increase fairly dramatically with height, into the 5000ft level with the low level jet. These low level winds will be strongest at the end of the forecast. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SATURDAY... FORECAST CONFIDENCE: High. ALTERNATE SCENARIOS: EKN may dip into IFR for vsby tonight with fog if low level flow is not strong enough. 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. DATE FRI 02/24/17 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EST 1HRLY 01 02 03 04 05 06 07 08 09 10 11 12 CRW CONSISTENCY H H H H H H H H H H H M HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY H H H H H H H H H H H M EKN CONSISTENCY H H H H H H H H H H H M PKB CONSISTENCY H H H H H H H H H H H M CKB CONSISTENCY H H H H H H H H H H H M AFTER 06Z SATURDAY... No widespread IFR conditions are expected at this time. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...MPK/26 NEAR TERM...26 SHORT TERM...MPK LONG TERM...MPK AVIATION...26 is the U.S. government's official web portal to all federal, state and local government web resources and services.