Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 301318
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
918 AM EDT THU APR 30 2015

.SYNOPSIS...
VIGOROUS MID/UPPER LOW PRESSURE DIGS SOUTH FROM LOWER GREAT LAKES
THIS MORNING...PASSES TONIGHT. INSTABILITY SHOWERS THEN LINGERING
LOWER CLOUDS/SHOWERS OVERNIGHT. WEAK HIGH PRESSURE FOR WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
ADJUSTED UP HOURLY POPS TO BETTER REFLECT ECHOES ON RADAR MOVING
INTO SOUTHEAST OH...EXPECTED TO SPREAD INTO PORTIONS OF WV THIS
AFTERNOON AND EVENING. REST OF FORECAST REMAINS REPRESENTATIVE.

PREVIOUS DISCUSSION BELOW...
AT THE EARLY HOUR OF 08Z THIS MORNING...THE MID LEVEL CIRCULATION
ON SATELLITE IMAGERY WAS BETWEEN TVC AND GRR IN WESTERN LOWER
MICHIGAN. OUR STEERING FLOW IS CURRENTLY SW OR W AHEAD OF THIS
FEATURE. SHOWERS OVER THE MOUNTAIN COUNTIES HAVE BEEN STRUGGLING
TO FORM ALL NIGHT. CLOUDS AT 6 TO 10 THSD FT AGL ARE FORMING PAST
FEW HOURS IN THE RELATIVE DRIER SLOT FROM 6L4 TO CRW TO PKB-CKB.

MID LEVEL CIRCULATION STILL PROJECTED TO DROP SSE ACROSS EASTERN
KENTUCKY AROUND 00Z FRIDAY...THEN THROUGH SW VIRGINIA 03-06Z FRIDAY.

AS A RESULT...THE COLDEST POCKET OF AIR SHOULD BE OVER OUR SOUTHERN
COUNTIES 21Z TODAY TO 00Z FRIDAY. FOR EXAMPLE...THE 00Z NAM DROPS
THE 500 MB TEMPERATURE ABOUT 3 TO 4 DEGS C THERE...BUT HARDLY DROPS
THE 500 MB TEMPERATURE AT ALL IN THE PKB TO CKB VCNTY. AS A
RESULT...MORE INSTABILITY FIGURED FOR AREAS FROM EXTREME SOUTHERN
OHIO TO HTS-CRW AND BKW ON SOUTH TO INCLUDE OUR 2 VIRGINIA
COUNTIES...COMPARED TO FURTHER NORTH.  MODEL SOUNDINGS SHOWING VERY
NARROW CAPE WITH EQUILIBRIUM LEVEL AROUND 15 THSD FT IN THE NORTH TO
OVER 20 THSD FT IN THE SOUTH. WITH THE FREEZING LEVEL SO
LOW...AROUND 6 TO 7 THSD FT...SOME ICE COULD REACH THE GROUND EVEN
WITHOUT T.  WILL INCLUDE THAT SMALL HAIL POSSIBILITY IN THE WEATHER
GRIDS FOR THOSE SOUTHERN COUNTIES...WITH POSSIBLE T ANYWHERE.  OF
COURSE...WITH SUB SEVERE HAIL FIGURED...THIS WILL NOT BE HIGHLIGHTED
IN OUR HAZARDOUS WEATHER POTENTIAL.

HARD TO PAINT EXACTLY HOW THE SHOWERS WILL EVOLVE AND SPIN AROUND
THE MID LEVEL CIRCULATION LATE TODAY AND INTO THIS EVENING FOR EACH
HOUR.  AS THE MID LEVEL LOW DROPS TOWARD OUR SOUTHERN COUNTIES BY
00Z FRIDAY...SHOWERS NORTH OF IT WILL SHOW LITTLE MOVEMENT. DESPITE
PRECIPITABLE WATER ONLY AROUND 0.75 INCHES...WILL STILL NEED TO
MONITOR RAIN AMOUNTS TONIGHT IN THAT WRAP AROUND ON NORTH SIDE OF
THE MID LEVEL LOW.

TRIED TO HAVE A MAXIMUM TEMPERATURE AROUND MIDDAY...BUT AFTERNOON
TEMPERATURES MAY BE HIGHLY VARIABLE IN AND OUT OF THE SHOWERS.

CEILINGS LOWER 03Z TO 06Z FRIDAY. LINGERING LIGHT SHOWERS THROUGH
THE NIGHT WITH LIKELY POPS STILL AFTER MIDNIGHT CKB-CRW ON E-SE.

DID LOWER MINIMUM TEMPERATURE TONIGHT OVER THE HIGH TERRAIN OF THE
SOUTH FROM BKW TO NORA...850 COOL POCKET THERE...COMPARED TO FURTHER
NORTH.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
TO START THE PERIOD...AN UPPER LEVEL LOW WILL BE SPINNING OVER THE
CAROLINAS. WRAPAROUND MOISTURE WILL BE FLOWING INTO THE NORTHEASTERN
QUADRANT OF THE CWA...AND HAVE HIGH CHANCE POPS THERE ON
FRIDAY...TAPERING OFF TO SLIGHT CHANCE ACROSS WESTERN WV AND DRYING
WEST OF THE OHIO RIVER BY AFTERNOON. SEVERAL WEAK IMPULSES ROTATE IN
FROM THE NORTH AS THE UPPER LOW HEADS OUT TO SEA. THE STRONGEST OF
WHICH WILL CROSS ON SATURDAY. STILL ENOUGH MOISTURE IN THE NORTHERN
MOUNTAINS TO INCLUDE A SLIGHT CHANCE POP PER THE NAM/ECMWF. THE NAM
AND THE ECMWF ALSO SHOW A WEAK SHORTWAVE TROUGH AND VORT MAX SLIDING
IN FROM THE NORTHER PLAINS ON SATURDAY...BUT ARE NOT PRINTING OUT
ANY QPF WITH THIS FEATURE. THE GFS ON THE OTHER HAND...ALMOST TRIES
TO COMBINE THE TWO AFOREMENTIONED FEATURES OVER THE GREAT
LAKES...AND IS MORE ROBUST WITH PRECIP ON SATURDAY. FOR NOW STUCK
CLOSER TO THE NAM/ECMWF. WITH HIGH PRESSURE NOSING IN AT THE
SURFACE...THINK WE SHOULD BE TO STABLE ACROSS THE LOWLANDS FOR
SHOWERS. FRIDAY WILL STILL BE A COOL DAY WITH PLENTY OF
CLOUDS...ALTHOUGH SOME SUN PEAKING OUT LATE IN THE WEST. SATURDAY
SHOULD BE A GOOD DEAL WARMER IF WE DO INDEED STAY DRY AND SEE MORE
OF SUNSHINE. MAY BE TOO WARM ON SATURDAY IF GFS IS RIGHT AND WE SEE
SCATTERED SHOWERS.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
USED A BLEND OF THE NAEFS MEAN AND THE ECENS MEAN. THIS WOULD HAVE
HIGH PRESSURE IN CONTROL FOR SATURDAY NIGHT AND SUNDAY. AS THE HIGH
SLIDES EASTWARD EARLY IN THE NEXT WORK WEEK...MOISTURE INCREASES.
THIS MAY ALLOW FOR SOME AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS. BY MID WEEK...A FRONTAL BOUNDARY SLIDE DOWN INTO
SOUTHEAST OHIO AND NORTHERN WEST VIRGINIA.

&&

.AVIATION /13Z THURSDAY THROUGH MONDAY/...
CONFIDENCE LOWERED TO MEDIUM IN TRYING TO TIME INSTABILITY CLUSTERS
OF SHOWERS ASSOCIATED WITH THE STRONG MID/UPPER LEVEL DISTURBANCE.
ALSO...CONFIDENCE LOWERED IN TRYING TO TIME LOWERING CEILINGS 03Z TO
06Z FRIDAY IN THE WAKE OF THIS SYSTEM.

SCATTERED LIGHT SHOWERS POSSIBLE THRU 17Z. CLOUDS MOSTLY 4 TO 8 THSD
FT AGL THIS MORNING.

COLD POCKET IN THE MID LEVELS MOVES TOWARD EASTERN KENTUCKY AND
SOUTHERN OHIO 18Z TO 21Z...THEN ACROSS SOUTHERN WEST VIRGINIA LATE
TODAY...REACHING SOUTHWEST 00Z TO 03Z FRIDAY. THIS SHOULD PROVIDE
HIGHLY VARIABLE CONDITIONS IN SCATTERED SHOWERS DURING THE AFTERNOON
AND EARLY EVENING HOURS...WITH EMBEDDED THUNDER IN THE STRONGEST
CELLS.  SMALL HAIL POSSIBLE UNDER THE COLD POCKET ALOFT...MAINLY
SOUTHERN COUNTIES. IT WOULD NOT EVEN TAKE THUNDER FOR SOME ICE TO
REACH THE GROUND IN A SHOWER. IN TAFS WILL INCLUDE CATEGORICAL
SHOWERS FOR A TIME FRAME WITH MVFR VSBY...BUT DID NOT INCLUDE
THUNDER SINCE COVERAGE EXPECTED TO BE LIMITED.

BETWEEN 03Z TO 06Z FRIDAY...CEILINGS LOWERING INTO WIDESPREAD 2
THSD FT AND VSBY 3 TO 5 MILES IN LINGERING LIGHTER SHOWERS.

AFTER 06Z...IFR IN CEILINGS AND VSBY MAY DEVELOP OVER THE MOUNTAIN
COUNTIES INCLUDING BKW.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY...

FORECAST CONFIDENCE: MEDIUM.

ALTERNATE SCENARIOS: TIMING OF -SHRA AND -TSRA MAY VARY FROM
FORECAST. LOWERING CEILING TONIGHT MAY TAKE LONGER TO DEVELOP THAN
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       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    M    M    M    H    M    M    M    M
HTS CONSISTENCY  H    H    M    M    M    M    M    M    M    H    H    H
BKW CONSISTENCY  H    H    H    H    H    H    M    H    M    M    M    M
EKN CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
PKB CONSISTENCY  H    H    H    H    H    H    H    M    M    M    M    M
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    M    M    H

AFTER 12Z FRIDAY...
IFR CEILINGS AND LIGHT RAIN SHOWERS/EVEN DRIZZLE MAY LINGER TO 18Z
FRIDAY AFTERNOON OVER SOUTHERN MOUNTAIN COUNTIES.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.

&&

$$
SYNOPSIS...KTB/MZ
NEAR TERM...KTB/ARJ
SHORT TERM...MZ
LONG TERM...RPY
AVIATION...KTB








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