Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 250522
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
122 AM EDT SAT APR 25 2015

.SYNOPSIS...
A WARM FRONT BECOMES STATIONARY ACROSS THE AREA SATURDAY. LOW
PRESSURE RIDES EAST ALONG THE FRONT AND PASSES WV BY SATURDAY NIGHT.
CHILLY NORTH FLOW SUNDAY NIGHT THROUGH MONDAY BEHIND THE LOW.

&&

.NEAR TERM /THROUGH TODAY/...
8 PM UPDATE. INCREASED CLOUDS FASTER OVERNIGHT WITH SHOWERS RAPIDLY
SPREADING NORTHWARD ON SATURDAY.

PREVIOUS DISCUSSION...
CHANGEABLE WX IN THE NEAR TERM...RESULTING IN AN UNSETTLED
SATURDAY. CIRRUS WILL BE ON THE INCREASE THIS EVENING...WITH MID
LEVEL CLOUDS TO FOLLOW OVERNIGHT. GIVEN THE VERY DRY AIR NEAR THE
SURFACE...THINK A QUICK DROP IN TEMPS THIS EVENING ONCE THE WIND
SLACKENS...ESPECIALLY OFF THE HILLTOPS. THIS MAY ALLOW FOR SOME
MID 30S AFTER MIDNIGHT...ESPECIALLY N ZONES. THERE COULD BE SOME
BRIEF PATCHY FROST BEFORE CLOUDS BECOME THE RULE UP THAT WAY.

FOR SATURDAY...WILL BE FOLLOWING A DEVELOPING BAROCLINIC ZONE/WARM
FRONT EXTENDING FROM MS VALLEY LOW PRESSURE INTO OUR REGION. QUITE
A BIT OF LIFT AND LOW LEVEL CONVERGENCE WILL BE BATTLING
INITIALLY DRY LOW LEVELS FOR BANDS OF SHRA TO ROLL THRU SATURDAY
MORNING FROM SW TO NE. THIS MAY BREAK UP A BIT AS IT HEADS INTO N
WV AND E OH. NOT EXPECTING MUCH QPF WITH THIS AS IT WORKS
THRU...GENERALLY A QUARTER INCH OR LESS.

THINK A LULL WILL BE IN THE CARDS FOR THE AFTERNOON AS FORCING
SHIFT N OF CWA AND AREA AWAITS ARRIVAL OF LOW PRESSURE FROM THE W.
THERE PROBABLY WILL BE A GOOD TEMP GRADIENT FROM S TO N WITH S
AREAS REACHING LOW TO MID 60S...WHILE E OH AND N WV STRUGGLE TO
SURPASS LOW 50S.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
STRONG BAROCLINIC ZONE SETS UP FROM WNW TO ESE ACROSS CWA ON
SATURDAY. EXAMPLE...00Z GFS HAS 18Z SAT 850 TEMPS FROM +5C CKB TO
+10 NEAR GRUNDY.

WITH SOUTHEAST FLOW AND INCREASING POPS...ON NORTH SIDE OF THE
FRONTAL BOUNDARY...HAD TO LOWER MAXIMUM TEMPERATURES ESPECIALLY ON
THE SOUTHEAST UPSLOPE AREAS.

SOME RENEGADE LIGHT RAIN SHOWERS OR SPRINKLES MAY TRY TO REACH THE
GROUND OVER NRN COUNTIES 12Z TO 16Z SATURDAY...BUT OVERALL WAS
SLOWER INCREASING THE POPS NORTH OF THE ROUTE 50 CORRIDOR SATURDAY.

WILL TRY TO PAINT A LULL OR DECREASE IN THE POPS LATER SATURDAY
AFTERNOON IN THE SOUTHERN LOWLANDS AFTER THE INITIAL SHOWERS PULL
NORTH AND EAST.

FIGURING THE SURFACE LOW WILL BE A BIT SLOWER THAN THE 00Z NAM
SOLUTION...MORE TOWARD THE GFS AND ECMWF SOLUTIONS.  HAVE WEAKENING
SURFACE LOW PASSING THROUGH SOUTHERN WEST VIRGINIA 06Z TO 12Z
SUNDAY.  BEST SUPPORT AND INSTABILITY FOR TALLER THUNDERSTORMS
SHOULD BE TO OUR WEST AND SOUTHWEST AT 00Z SUNDAY...SAY OVER CENTRAL
KENTUCKY...BUT MAY CARRY EAST INTO OUR SOUTHERN COUNTIES SATURDAY
EVENING. WILL INCLUDE BOTH THE WATER AND SEVERE CONCERNS IN OUR
HAZARDOUS WEATHER OUTLOOK.  SHOWERS COULD BECOME ALIGNED WEST TO
EAST ALONG THE FLOW. THINKING 1.5 INCHES OF RAIN OR MORE WOULD BE
NEEDED IN 3 HOURS FOR CONCERNS ALONG SMALL STREAMS.

A COOLER NORTH FLOW TAKES OVER FOR SUNDAY NIGHT INTO MONDAY.  WILL
KEEP SOME 20 TO 30 POPS FOR LIGHT RAIN AND SNOW SHOWERS OVER NORTHERN
WEST VIRGINIA COUNTIES.

ENOUGH CONFIDENCE TO REMOVE POPS FOR TUESDAY AS WE REMAIN IN THE
CIRCULATION OFF THE EAST COAST.  WILL HOLD THE MOISTURE INCREASING
FROM THE SOUTHWEST UNTIL WEDNESDAY.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AFTER THE MID ATLANTIC LOW EXITS...UPPER LOW RETROGRADES FROM
ATLANTIC CANADA SOUTHWESTWARD INTO NEW YORK STATE...DROPPING A WEAK
TROUGH AXIS IN FROM THE NORTH. CARRY LOW END MOUNTAIN POPS FOR THIS
FEATURE FOR MONDAY...WITH HIGH PRESSURE MOVING IN FOR TUESDAY.
OPERATIONAL MODELS DIVERGE SIGNIFICANTLY AFTER MONDAY...WITH THE GFS
BRINGING A LOW PRESSURE SYSTEM ACROSS THE SOUTH AGAIN...WHILE THE
00Z ECMWF KEEPS THE CWA DRY THROUGH THE EXTENDED. GOING CLOSER TO
THE GFS FOR THIS ISSUANCE WITH SOME BELOW AVERAGE CONFIDENCE WITH
THE POPS THROUGH THE MIDDLE OF THE WEEK.

&&

.AVIATION /05Z SATURDAY THROUGH WEDNESDAY/...
VFR SHOULD REMAIN IN PLACE THROUGH THE EARLY MORNING
HOURS...ALTHOUGH CLOUDS WILL BE INCREASING AND LOWERING. A WARM
FRONT SETS UP ACROSS THE SOUTHERN CWA...WITH SHOWERS SPREADING
NORTH TODAY. EXPECT MVFR WITH THESE...AND COULD EVEN GET BRIEF
PERIODS OF IFR VISIBILITY. DID NOT INCLUDE THIS IN THE TAF DUE TO
LOW CONFIDENCE...BUT BEST CHANCE WOULD BE ACROSS THE SOUTH. LOW
PRESSURE PASSES JUST TO OUR SOUTH TONIGHT...WITH ANOTHER BATCH OF
SHOWERS...MAINLY ACROSS THE SOUTH. COULD GET A RUMBLE OF THUNDER
WITH THIS BUT AGAIN LEFT OUT DUE TO UNCERTAINTY.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY...

FORECAST CONFIDENCE: MEDIUM.

ALTERNATE SCENARIOS: CONDITIONS MAY LOWER TO IFR TODAY AND TONIGHT IN
THE HEAVIER RAIN SHOWERS SOUTH.

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                              SAT 04/25/15
UTC 1HRLY       06   07   08   09   10   11   12   13   14   15   16   17
EDT 1HRLY       02   03   04   05   06   07   08   09   10   11   12   13
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    M    M    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    H    H
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 06Z SUNDAY...
IFR POSSIBLE IN STRATUS LATE SATURDAY NIGHT INTO SUNDAY AS RAIN
DIMINISHES...MAINLY IN THE MOUNTAINS.

&&

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

&&

$$
SYNOPSIS...RPY/JMV/30/26
NEAR TERM...JMV/30
SHORT TERM...RPY
LONG TERM...26
AVIATION...MZ







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