Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 081047
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
547 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 DENDRITE 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/...
A DEEP LOW PRESSURE/TROUGH BRINGS A SERIES OF SHORT WAVES ACROSS THE
AREA THROUGH THE PERIOD. THIS WILL CONTRIBUTE TO BELOW NORMAL
TEMPERATURES AND PERIODS OF SNOW SHOWERS.

THE GFS/ECMWF/NAM ARE IN AGREEMENT WITH THE TIMING AND INTENSITY
OF THE PCPN. THE GFS/NAM SOLUTIONS SUGGEST SIGNIFICANT SNOWFALL
TUESDAY AND WEDNESDAY...CONTINUING INTO THURSDAY. 2 TO 4 INCHES OF
SNOW WILL BE COMMON...DEPENDING ON WHERE A SNOW BAND SET UP.

OUTSIDE WIDESPREAD UPSLOPE SNOW SHOWERS...MODELS DEPICT A LAKE MI
TRAJECTORY COMING ACROSS THE NRN TIER OF THE FCST AREA BY TUESDAY...ENHANCING
LOWLAND SNOW AMOUNTS THERE VS. AREAS FARTHER S.

WITH H85 TEMPERATURES DROPPING INTO THE TEENS BELOW ZERO C TUE
AND SLOWLY DROPPING FURTHER BEYOND THAT...BELIEVE ALL PCPN WILL BE
IN FORM OF SNOW. DESCENT OMEGA WITHIN THE DENDRITE SUGGEST LOCALIZED
BURSTS OF SNOW ARE POSSIBLE WHERE OMEGA REACH 15 TO 20 MICRO BARS
PER SECOND. 3 TO 5 INCHES OF SNOW CAN BE EXPECTED IN A TIME PERIOD
OF 24 TO 36 HOURS. ISSUED WINTER WEATHER ADVISORY FOR MOST PLACES
FOR SNOW WITH THE MODEL CONSENSUS.

WENT GENERALLY WITH THE ALLBLEND AND SUPERBLEND FOR TEMPERATURES
THROUGH THE PERIOD.

&&

.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 DENDRITE 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 /12Z MONDAY THROUGH FRIDAY/...
STILL EXPECTING DETERIORATING CONDITIONS TODAY WITH A COLD FRONT
AND POST FRONTAL RAIN TURNING TO SNOW BY THIS EVENING/TONIGHT.
PREVAILING MVFR TO IFR LIKELY FOR ALL SITES...ESPECIALLY ONCE THE
LOWEST LEVELS SATURATED AFTER A FEW HOURS OF PRECIPITATION. THIS
APPLIES TO BOTH CEILINGS AND VISIBILITIES. SNOW SHOWERS TONIGHT
WILL ALSO CARRY PREVAILING IFR VISIBILITIES FOR ALL TERMINALS.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z 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. MAY
NEED A COUPLE HOURS OF IMPROVED FLIGHT CATEGORIES LATER TODAY.

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       10   11   12   13   14   15   16   17   18   19   20   21
EST 1HRLY       05   06   07   08   09   10   11   12   13   14   15   16
CRW CONSISTENCY  H    H    M    M    M    L    L    L    L    L    M    M
HTS CONSISTENCY  H    M    M    L    L    L    L    M    M    M    M    M
BKW CONSISTENCY  H    H    H    M    M    L    L    L    L    L    L    L
EKN CONSISTENCY  H    H    H    H    H    H    H    M    M    L    L    L
PKB CONSISTENCY  H    H    H    M    M    L    L    L    L    M    M    M
CKB CONSISTENCY  H    H    H    H    H    H    M    M    M    M    L    L

AFTER 12Z 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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