Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 172320
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
715 PM EDT FRI APR 17 2015

.SYNOPSIS...
WEAK HIGH PRESSURE FOLLOWS TONIGHT AND SATURDAY. WARM FRONT
CROSSES SUNDAY EVENING. COLD FRONT CROSSING MONDAY MAY HERALD A
PERIOD OF COOLER WEATHER. ANOTHER COLD FRONT WEDNESDAY OR THURSDAY.

&&

.NEAR TERM /THROUGH SATURDAY/...
DEW POINTS HAVE FALLEN IN SOUTHEAST OHIO.  EVEN PKB WENT FROM 53 TO
50 FROM 21Z TO 23Z.  HOWEVER...IN WEAK FLOW...STILL THINKING HIGHER
DEW POINTS WILL HOLD FROM NEAR CKB ON SW TO CRW.  SO WE WILL HAVE
PATCHY FOG FORMING...THINKING FIRST IN THE CKB TO EKN CORRIDOR TOWARD
MIDNIGHT.  ALSO CONCERNED THE CIRRUS OF VARYING THICKNESS MAY
DELAY FOG IN THE SOUTH.

STILL HARD TO DETERMINE IF LOW STRATUS FORMS IN NE LOW LEVEL FLOW FOR
09Z TO 12Z SATURDAY IN CKB TO CRW TO WILLIAMSON CORRIDOR.


&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
VERY GOOD MODEL AGREEMENT THIS PERIOD...ESPECIALLY IN THE MASS
FIELDS.

UPPER LOW THAT HAS BEEN HANGING AROUND THE FOUR CORNERS AREA OVER
THE SOUTHWEST U.S. WILL BE RAPIDLY KICKED OUT BY A VIGOROUS NORTHERN
STREAM SHORT WAVE THAT COMES OVER THE WEST COAST UPPER RIDGE.
ASSOCIATED SURFACE LOW WILL DEVELOP OVER THE LOWER MISSISSIPPI
VALLEY SATURDAY NIGHT...AND LIFT RAPIDLY NORTHWARD WITH THE LEAD
UPPER SYSTEM INTO LAKE MICHIGAN BY MONDAY MORNING. THIS...IN
TURN...WILL DRIVE A WELL DEFINED FRONT OF PACIFIC ORIGIN NORTHEAST
ACROSS THE AREA SUNDAY. THE COMBINATION OF A WELL DEFINED NEGATIVE
TILT TO THE SYSTEM...GOOD LOW LEVEL CONVERGENCE...AND INCREASINGLY
MOIST BUT MARGINALLY UNSTABLE AIR...WILL RESULT IN A WIDESPREAD BAND
OF SHOWERS WITH PERHAPS AN EMBEDDED THUNDERSTORM SUNDAY...MUCH LIKE
A WARM FRONT SCENARIO. WHILE MODERATE SOUTHEAST FLOW AHEAD OF THE
FRONT WILL TEND TO CREATE SOME DOWNSLOPING AND A SHADOW AREA IN THE
RAIN BAND BETWEEN THE OHIO RIVER AND THE MOUNTAINS...THE UPPER
DYNAMICS LOOK TO BE STRONG ENOUGH TO PUT CAT POPS EVERYWHERE IN THIS
BAND...BUT SOMEWHAT LOWER QPF IN THE SHADOW ZONE. THIS FAST MOVING
FEATURE IS NOT EXPECTED TO BE A FLOODING ISSUE.

BEHIND THIS LEAD SYSTEM...A COLD FRONT ACCOMPANYING THE NORTHERN
STREAM SHORT WAVE WILL ALSO MOVE RAPIDLY ACROSS THE AREA MONDAY.
THIS TIME...ENOUGH INSTABILITY WILL BRING MORE THUNDER WITH THE
FRONT AS IT MOVES ACROSS MONDAY. THERE MAY BE A RELATIVE BREAK IN
SHOWERS SUNDAY NIGHT IN THE WARM SECTOR...BUT WILL CONTINUE CHANCE
POPS. EXPECT A BAND OF CONVECTION WITH THE FRONT MONDAY...SO GOING
LIKELY WITH SHOWERS AND THUNDERSTORMS. TOO EARLY TO TELL ABOUT
SEVERE THUNDERSTORM POTENTIAL WITH THE FRONT...BUT NO FLOODING
ISSUES ARE AGAIN EXPECTED DUE TO ITS PROGRESSIVE NATURE.

FOR TEMPERATURES...LOOK FOR NEAR SEASONAL READINGS.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
COLD FRONT WILL BE EAST OF THE CWA TO START THE LONG TERM...AND HAVE
DECREASING POPS MONDAY NIGHT. SLOW MOVING UPPER LEVEL LOW PASSES TO
OUR NORTH THROUGH THE WEEK WITH SEVERAL IMPULSES IN THE WEST TO
NORTHWESTERLY FLOW...AND HAVE SOME PERIODS OF CHANCE POPS. MODELS
ALSO SHOWING A COLD FRONT WEDNESDAY INTO THURSDAY. WITH SOME TIMING
DIFFERENCES...BLENDED IN WPC GUIDANCE.

&&

.AVIATION /23Z FRIDAY THROUGH WEDNESDAY/...
DESPITE RELATIVELY DRY PEACEFUL PATTERN LOWERED CONFIDENCE TO LOW.
THIS IS BASED ON TRYING TO FIGURE FOG FORMATION...COVERAGE AND ITS
THICKNESS IN WEST VIRGINIA FOR 04Z TO 12Z SATURDAY.

DEW POINTS HAVE LOWERED IN SOUTHEAST OHIO.  PKB HAS FALLEN FROM 53
TO 50 FROM 21Z TO 23Z FRIDAY. YET...STILL THINKING THE HIGHER
SURFACE DEW POINTS WILL LINGER FROM CKB ON TO CRW OVERNIGHT.  WITH
THE SPOTTY SHOWERS THIS AFTERNOON...THINKING CKB TO EKN VCNTY MAY BE
THE FIRST TO SEE THE FOG FORMATION FROM 04Z TO 06Z.  THE CIRRUS IN
THE SOUTH MAY DELAY THE FOG. SOME MODEL SOLUTIONS...LIKE THE 18Z
NAM...STILL TRY TO FORM STRATOCUMULUS AT 2 TO 3 THSD FT IN SRN WV BY
06Z.  THINKING IF CLOUDS REFORM IT WOULD BE MOSTLY THE STRATUS
VARIETY AOB 1 THSD FT IN THE CKB-CRW TO WILLIAMSON CORRIDOR.

HTS AND BKW ARE ESPECIALLY TOUGH TO FIGURE.  WENT INTO MVFR IN FOG
FOR HTS DURING THE PREDAWN HOURS SINCE DEW POINTS STILL STRUGGLING
TO FALL BEFORE SUNSET.  BKW ON THE SOUTHERN PLATEAU MAY GET CLOUDS
INSTEAD OF THICKER FOG.

ALL IN ALL...THE FOG AND LOW CLOUD DILEMMA SHOULD BE GONE AFTER 13Z.
VFR 14Z SATURDAY TO 00Z SUNDAY.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SUNDAY...

FORECAST CONFIDENCE: LOW.

ALTERNATE SCENARIOS: FOG AND LOW STRATUS TIMING/COVERAGE/THICKNESS
MOSTLY 06Z TO 12Z SATURDAY COULD VARY GREATLY IN WEST VIRGINIA FROM
DETERMINISTIC 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       20   21   22   23   00   01   02   03   04   05   06   07
EDT 1HRLY       16   17   18   19   20   21   22   23   00   01   02   03
CRW CONSISTENCY  H    M    M    M    M    M    M    M    M    M    M    M
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    M    H    M    M    M    M    H    M    M
PKB CONSISTENCY  M    M    M    H    H    M    M    M    H    H    H    H
CKB CONSISTENCY  H    H    M    M    M    M    M    M    M    M    M    M

AFTER 00Z SUNDAY...
IFR POSSIBLE IN MOSTLY SHOWERS SUNDAY AFTERNOON INTO SUNDAY
NIGHT...AND SHOWERS OR THUNDERSTORMS MONDAY INTO MONDAY EVENING.

&&

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

&&

$$
SYNOPSIS...JMV/MZ/26
NEAR TERM...KTB
SHORT TERM...JMV
LONG TERM...MZ
AVIATION...KTB









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