Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 121840 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 140 PM EST Fri Jan 12 2018 .SYNOPSIS... A southern stream low pressure system moves northeast across the region today into Saturday. Arctic air returns for the weekend. Low pressure crosses Monday into Tuesday. Still cold. && .NEAR TERM /THROUGH TONIGHT/... As of 915 AM Friday... Break in the action this morning with lingering high water across parts of the northern Lowlands where up to 2.5 inches of rain fell overnight. Generally 1 to 1.5 inches fell elsewhere in the axis of concern. Not much change in reasoning from the mid shift so far this morning. Reworked the hourly grids using the latest HRRR/NAM which essentially resulted in little change with changeover time thru 00Z. Current headlines start at 21Z everywhere and is probably a bit soon across southeast Ohio and at least 6 hours too soon with the start time east of the Ohio River. I elected to push back start time across WV zones to 00Z and this may even be a bit too soon. The 12Z NAM is rolling in and has backed off on the eastward extent of warning criteria snow, which had it spilling over into the northern Lowlands much like the 00Z Euro. I`ll wait to see the new GFS before any decision on expansion. If nothing changes, the current extent of warnings look good. Elsewhere, not sure the eastward extent of the advisory is going to meet criteria, but given the travel impacts expected with a strong flash freeze potential Saturday morning...I will hold and and expand the advisory into the mountains for impact. As of 435 AM Friday... Details for upcoming winter storm in a little better agreement this shift. Band of moderate to heavy rain across the Ohio Valley overnight will gradually exit to the north later this morning. Expecting a brief lull in the heavier precipitation to start today, however, this will quickly change, as an upper low/shortwave trough across the southern U.S. moves north and east towards the area, along with deepening/strengthening surface low, which will move northeast along the eastern edge of the CWA. Strong jet dynamics and good moisture feed will create moderate to heavy precipitation at times, particularly across parts of southeast Ohio and counties near to the Ohio River where shortwave trough will aid in greater lift. Precipitation is expected to start out as rain area wide, but will change over to a period of sleet and freezing rain, before transitioning to all snow, as a strong cold front pushes east through the region. This will result in quite the sharp temperature drop later this evening and tonight, along with gusty winds in the strong CAA. Front will enter southeast Ohio by 18 to 21Z, and exit the CWA by around 09Z Saturday. This will be a heavy wet snow, with snow to liquid ratios averaging around 11:1. In addition, expecting up to a tenth of ice, mainly across southeast Ohio zones. Generally east of the Ohio River, will still see a wintry mix, but am expecting a much quicker change over to snow. Based on aforementioned features and forcing expected, particularly across the north, have elected to upgrade the advisory across parts of southeast Ohio to a winter storm warning. At this point, not seeing a greater expansion of the advisory, but possible future shifts will have to reevaluate this. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 435 AM Friday... The cold is back. The near term system pulls out quickly on Saturday. Upslope snow showers quit by afternoon, with less than an inch additional accumulation. The arctic air returns, with arctic high pressure building in for the balance of the weekend, beneath short wave ridging within an upper level long wave trough. Within the long wave, the upper level short wave trough associated with the near term system lifts out early in the weekend, and the next short wave trough digs in from the northwest late in the weekend. A southern stream feature, it seems to slip harmlessly south of the area Sunday night. A northern stream short wave trough digs into the midwest Sunday night, and begins to close off. Warm advection low level southerly flow ensues ahead of the associated surface low and cold front, resulting in increasing cloudiness Sunday night, and the chance for light snow knocking on the doorstep from the west toward dawn Monday. Went below central guidance temperatures Saturday morning, as cold advection keeps temperatures dropping in the morning, before level off and recovering slightly in the afternoon. Lows Saturday night were also adjusted down a bit, per arctic high pressure overhead. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 435 AM Friday... A positively tilted upper level short wave trough, nearly closed off early on over the upper midwest, crosses Monday into Wednesday. Warm advection light snow is possible Monday, followed by snow showers with the cold front Monday night, and then upslope snow showers Tuesday into Wednesday. The cessation of the upslope snow showers later Wednesday or early Thursday will depend upon how quickly the upper level trough lifts out, and a large high pressure center of arctic origin builds in from the southwest. That high ensures a dry end to the period. With the exodus of the short wave trough comes the exodus of long wave troughing in the east, and this deep freeze looks like a one week or less event, compared with its two week long predecessor. Central guidance temperatures accepted, except lowered lows a bit in cold advection Tuesday night. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
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18Z Friday thru 18Z Saturday... As of 130 PM Friday... A strong cold front will cross thru the afternoon with gusty nw winds and deteriorating conditions along and behind the front in rain. Rain will change to a brief period of freezing rain/sleet before changing to snow as the night progresses, with widespread IFR or worse conditions settling in. Snow will taper off from sw to ne early Saturday morning with improving conditions. MVFR stratus may linger into midday or early afternoon. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SATURDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing of category and precipitation changes may vary from 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 18 19 20 21 22 23 00 01 02 03 04 05 EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00 CRW CONSISTENCY M M H H H H H H H H M M HTS CONSISTENCY L H H H H H M L H M M M BKW CONSISTENCY H H H H H M H M L M M L EKN CONSISTENCY H H L L L L M M H M H L PKB CONSISTENCY L H H H H M M H H H H L CKB CONSISTENCY M M M L H H H H H H H M AFTER 18Z SATURDAY... IFR possible in wintry precipitation and low ceilings into Saturday.
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WV...Winter Weather Advisory from 7 PM this evening to 10 AM EST Saturday for WVZ005>011-013>020-024>034-039-040-515>526. OH...Winter Storm Warning until 10 AM EST Saturday for OHZ066-067- 075-076-083-084. Winter Weather Advisory until 10 AM EST Saturday for OHZ085>087. KY...Winter Weather Advisory until 10 AM EST Saturday for KYZ101>103-105. VA...Winter Weather Advisory from 7 PM this evening to 10 AM EST Saturday for VAZ003-004.
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&& $$ SYNOPSIS...RPY/30 NEAR TERM...SL/30 SHORT TERM...TRM LONG TERM...TRM AVIATION...30 is the U.S. government's official web portal to all federal, state and local government web resources and services.