Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 080906
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
406 AM EST MON FEB 8 2016

.SYNOPSIS...
COLD FRONT TODAY. UNSETTLED/COLDER TUESDAY AND WEDNESDAY UNDER
LARGE MID/UPPER LEVEL LOW...WITH ROUNDS OF SNOW SHOWERS THAT
LINGER THROUGH MUCH OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
UPPER LEVEL LOW CONTINUES ITS SLOW TREK...DROPPING INTO THE GREAT
LAKES AND MIDDLE OHIO VALLEY. SURFACE FRONTAL SYSTEM COUNTERPART
WILL TAKE A COLD FRONT THROUGH THE AREA TODAY...FOLLOWED BY A SERIES
OF UPPER LEVEL VORTICITY LOBES AND TROUGH AXES WELL INTO THE SHORT
TERM FORECAST PERIOD. EXPECTING A SIGNIFICANT CHANGE IN AIRMASS IN
TERMS OF TEMPERATURE WITH A PROLONGED PERIOD OF BELOW FREEZING
WEATHER BEGINNING TONIGHT.

SHOULD SEE A SLIGHTLY UNUSUAL PATTERN FOR THE TEMPERATURES AND
PRECIPITATION TYPE AS THE DAY EVOLVES. MAY SEE A LITTLE LIGHT SNOW
AT FIRST GIVEN THE POTENTIAL TO WET BULB...AS DEWPOINTS RESIDE IN
THE LOW TO MID 20S CURRENTLY WHILE TEMPERATURES ARE IN THE UPPER
20S TO MID 30S. SHOULD TRANSITION TO RAIN AS TEMPERATURES CLIMB
TO THE UPPER 30S AND LOWER 40S OVER THE LOWLANDS...AND FALL OFF
BEHIND THE FRONT THIS EVENING AND TONIGHT...CHANGING BACK TO SNOW.
THE HIGHER ELEVATIONS SHOULD NOT GET ABOVE FREEZING...SO THIS
SHOULD BE AN ALL SNOW EVENT FRONT THE GET GO...AND HENCE...THE
ADVISORY BEGINNING AT 18Z FOR RANDOLPH AND POCAHONTAS COUNTIES.

850MB TEMPERATURES DROP HARD TONIGHT IN THE TRANSITION TO A MUCH
COLDER ENVIRONMENT THAT WILL SUPPORT THE OFF AND ON SNOW
SHOWERS...BRIEFLY HEAVY AT TIMES. SHOULD NOT HAVE ANY ISSUES AT THE
ONSET WITH SATURATION IN THE DENDRITIC GROWTH LAYER...AND WILL SEE
MODEST ACCUMULATIONS BEGINNING TONIGHT...ESPECIALLY OVER THE
NORTHERN ZONES...AND IN THE NORTHEAST MOUNTAINS.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
DEEP L/W TROUGH OVER THE ERN U.S. THIS ENTIRE PERIOD SPELLS BELOW
NORMAL TEMPERATURES AND SNOW SHOWERS.

THE PARTY BEGINS RIGHT AT THE START OF THE PERIOD MON NT...WITH
COLD ADVECTION OVERSPREADING THE AREA FROM SW TO NE...BEHIND A NW
TO SE ORIENTED SFC LOW PRESSURE TROUGH EXTENDING FROM THE ERN
GREAT LAKES TO THE DELMARVA PENINSULA BY 12Z TUE. OUTSIDE
WIDESPREAD UPSLOPE SNOW SHOWERS...MODELS DEPICT A LAKE MI
TRAJECTORY COMING ACROSS THE NRN TIER OF THE FCST AREA MON NT INTO
TUE...ENHANCING LOWLAND SNOW AMOUNTS THERE VS. AREAS FARTHER S.

BEYOND THAT...TOUGH TO TIME THE SMALLER SCALE FEATURES ROTATING
AROUND THE EVOLVING UPPER LOW NEARBY TO THE N...BUT IT LOOKS LIKE
THE GENERAL TRAJECTORIES MAY NOT CHANGE MUCH. WITH H85
TEMPERATURES DROPPING INTO THE TEENS BELOW ZERO C TUE AND SLOWLY
DROPPING FURTHER BEYOND THAT...DENDRITIC CRYSTAL GROWTH IS
FAVORED...RESULTING IN HIGH SNOW TO LIQUID RATIOS.

FOR STARTERS...SNOW TOTALS FOR MON NT THROUGH TUE ARE CLOSE TO 12
HOUR ADVISORY CRITERIA BUT 3-5 INCHES SHORT OF WARNING CRITERIA ON
A COUNTY AVERAGE BASIS THROUGHOUT THE FCST AREA. THUS NOT
INTRODUCING ANY HEADLINES AT THIS TIME ALTHOUGH IT IS PLAUSIBLE
ADVISORIES WILL BE NEEDED FOR THAT PERIOD...AND THEN TUE NT INTO
WED LOOK TO BE NEARLY AS SNOWY WITH THE UPPER LEVEL LOW AND L/W
TROUGH AXIS STILL OVER THE UPPER AND MIDDLE OHIO VALLEYS. THE LAKE
MI TRAJECTORY INTO NRN PORTIONS OF THE FCST AREA MAY STILL BE
THERE OR MAY BE BECOMING REESTABLISHED WED AFTERNOON.

TEMPERATURES WERE LOWER THAN GUIDANCE BUT GENERALLY STAYED CLOSE
TO PREVIOUS PACKAGE AND RAW GUIDANCE IN THIS ANOMALOUS PNA
PATTERN...PERHAPS JUST SLOWING DOWN THE COOLING A BIT MON NT.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
STILL EXPECTING SCT SNOW SHOWERS OVER THE AREA WEDNESDAY NIGHT.
STREAMLINE ANALYSIS AND HYSPLIT BACKWARDS TRAJECTORY PARCELS ALONG
WITH OMEGA/RH IN THE DENDRITIC GROWTH ZONE DO INDICATE SOME
ENHANCEMENT FROM LAKE MICHIGAN FOR A TIME IN THE EVENING...AFFECTING
SE OH AND ESPECIALLY N WV. THIS IS ENHANCED FURTHER WITH A SUBTLE
VORT MAX ROUNDING THE BASE OF THE UPPER TROF.
SO...HAVE KEPT SOME FAIRLY HEALTHY POPS OVER THE N DURING THE NIGHT.
HOWEVER...EXPECT THIS TO BE A LOW QPF/HIGH POP SCENARIO WITH
GREATEST ACCUMULATIONS WEDNESDAY NIGHT OVER THE N WV MOUNTAINS WHERE
AN INCH OR TWO OF ADDITIONAL SNOW MAY FALL. THURSDAY MORNING WILL
FEATURE SOME LINGERING SNOW SHOWERS AND FLURRIES...PRIMARILY WITHIN
ANY LAKE MICHIGAN PLUME AS SHOWN ON GFS. H85 THERMAL TROF LINGERS IN
THE VICINITY SO HARD TO SEE MUCH IN THE WAY OF IMPROVEMENT WITH THE
EROSION OF THE STRATOCU AND ANY TEMPERATURE MODERATION.

WE FINALLY GET SOME WAA GOING THURSDAY NIGHT WHICH SHOULD BE ENOUGH
FOR SOME CLEARING AREAWIDE. AT THE SURFACE HIGH PRESSURE WILL BE
BUILDING IN WHICH WILL MAKE FOR A VERY COLD NIGHT SHOULD WE INDEED
LOSE THE CLOUDS AMID A FRESH SNOW PACK. SOME BELOW ZERO READINGS ARE
POSSIBLE IN THE IN THE TYPICAL COLD SPOTS OF THE MOUNTAIN VALLEYS.
CONFIDENCE BEGINS TO DECREASE HEADING INTO THE WEEKEND. THE GLOBAL
MODELS ARE HAVING SOME ISSUES RESOLVING FEATURES AND THE OVERALL
MEAN TROF OVER THE EASTERN CONUS. THUS HAVE STAYED CLOSE TO WPC
WHICH FAVORED A COLDER ECMWF SOLUTION FOR THE WEEKEND AMID ANOTHER
ARCTIC HAMMER DROP. NO BIG SYSTEM IS ENVISIONED OVER THE WEEKEND
THOUGH.

&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
EXPECTING OVERALL DETERIORATING AVIATION CONDITIONS THROUGH THE
TAF PERIOD...WITH A STRONG COLD FRONT PASSING THROUGH
TODAY...BRINGING RAIN CHANGING TO SNOW...LOWERING CEILING...AND
VISIBILITIES THAT WILL LIKELY BOUNCE IN AND OUT OF PRECIPITATION.

FOR THE CEILINGS...INTRODUCE MVFR NEAR THE ONSET...BUT HAVE IFR AT
SOME LOCATIONS AS THE LOWEST LEVELS SATURATE IN THE POST FRONTAL
ENVIRONMENT. WITH THE VISIBILITIES...GENERALLY USE MVFR WITH THE
ONSET AND IN RAIN...BUT IFR LIKELY AFTER SEVERAL HOURS OF LIGHT
RAIN...AND ESPECIALLY ONCE THE TRANSITION TO LIGHT SNOW OCCURS.

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

FORECAST CONFIDENCE...HIGH IN THE DETERIORATING TRENDS...AND MEDIUM
IN THE DETAILS AND TIMING.

ALTERNATE SCENARIOS: TIMING OF IFR WILL VARY. LOW LEVEL SATURATION
MAY REQUIRE EARLIER ONSET OF IFR ONCE THE COLD FRONT PASSES.

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                    MON 02/08/16
UTC 1HRLY       09   10   11   12   13   14   15   16   17   18   19   20
EST 1HRLY       04   05   06   07   08   09   10   11   12   13   14   15
CRW CONSISTENCY  H    H    M    M    M    L    L    M    M    M    M    M
HTS CONSISTENCY  H    H    M    L    L    M    M    M    M    M    M    M
BKW CONSISTENCY  H    H    H    M    M    M    L    L    L    L    L    M
EKN CONSISTENCY  H    H    H    H    H    H    H    M    H    H    H    M
PKB CONSISTENCY  H    H    M    L    L    L    L    M    M    M    M    M
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    M    M

AFTER 06Z TUESDAY...
PERIODS OF IFR CONDITIONS POSSIBLE IN RAIN/SNOW SHOWERS ALL THE
WAY THROUGH WEDNESDAY NIGHT...WITH THE WORST CONDITIONS EXPECTED
TUESDAY MORNING THROUGH WEDNESDAY MORNING.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST
     WEDNESDAY FOR WVZ005>011-013>020-024>040.
     WINTER WEATHER ADVISORY FROM NOON TODAY TO 7 AM EST WEDNESDAY
     FOR WVZ046-047.
OH...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST
     WEDNESDAY FOR OHZ066-067-075-076-083>087.
KY...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST
     WEDNESDAY FOR KYZ101>103-105.
VA...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST
     WEDNESDAY FOR VAZ003-004.

&&

$$
SYNOPSIS...ARJ/26
NEAR TERM...26
SHORT TERM...ARJ
LONG TERM...30
AVIATION...26


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