FXUS61 KRLX 070526
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
1226 AM EST MON DEC 7 2009
.SYNOPSIS...
HIGH PRESSURE DRIFTS EAST OVERNIGHT. WEAK FRONT MONDAY AFTERNOON.
WARM FRONTAL PRECIPITATION TUESDAY NIGHT. STRENGTHENING LOW PRESSURE
LIFTS NORTHEAST INTO GREAT LAKES WEDNESDAY WITH FRONT PASSING HERE.
&&
.NEAR TERM /THROUGH MONDAY/...
MINOR UPDATE TO THE FORECAST THIS EVENING...IN THAT THERE ARE PLENTY
OF HIGH CLOUDS REQUIRING INCREASE IN SKY GRIDS. HOWEVER...VERY GOOD
RADIATIONAL COOLING HAS QUICKLY HAPPENED THIS EVENING...DESPITE THE
CLOUDS...SO SOME SLIGHT LOWERING WAS NEEDED IN SPOTS ON THE LOW
TEMPERATURES. REST OF FORECAST ON TRACK.
PREVIOUS DISCUSSION...
HIGH PRESSURE IN CONTROL. CIRRUS MOVING OVERHEAD IN ZONAL FLOW
ALOFT. EXPECT A SLOW LOWERING/THICKENING OF CLOUD COVER WITH SLOW
WARM ADVECTION COMMENCING ON THE BACK SIDE OF THE DEPARTING HIGH.
SHOULD NOT BE ENOUGH WARMING FOR A NONDIURNAL TRACE...BUT DID KEEP
LOW TEMPS AT OR A TOUCH ABOVE THE WARMER MOS GUIDANCE.
SHEARING H500 SHORTWAVE LIFTS FROM THE MID MISSISSIPPI VALLEY
OVERNIGHT INTO THE EASTERN GREAT LAKES BY 00Z TUESDAY. WEAK
ASSOCIATED FRONTAL BOUNDARY TRIES TO LEAK THROUGH DURING THE DAY.
PREFER THE FASTER GFS/ECMWF TIMING TO THE SLOWER NAM GIVEN THE ZONAL
FLOW PATTERN. WITH MIDLEVEL SUPPORT STAYING TO THE NORTH AND
MOISTURE FIELD SPLITTING AS IT MOVES ACROSS...DO NOT THINK THAT
ANYTHING MORE THAN SLIGHT CHANCE POPS ARE JUSTIFIED. ANY FLAKES WILL
BE CONFINED TO THE RIDGES WITH MODERATING SURFACE TEMPS AND H850
TEMPS OF AROUND -2 TO -3. MAIN EFFECT WILL BE AN INCREASE IN LOWER
CLOUDS...AS H850 MOISTURE LAGS BEHIND THE BOUNDARY. KEPT HIGHS AT OR
BELOW THE COOLER MOS VALUES...BUT HIGHS IN THE 40S ARE FORECAST MOST
EVERYWHERE.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
MOISTURE MAINLY AT 850 MB AND BELOW MONDAY NIGHT. THE MOISTURE
THINS EVEN BELOW 850 MB OVERNIGHT...SO PARTIAL CLEARING POSSIBLE
ESPECIALLY ACROSS OUR N-NW COUNTIES. THIS CLOUD ISSUE MAKES FOR A
HARD MINIMUM TEMPERATURE FORECAST.
HAVE LESS CLOUDS ACROSS OUR NORTH TUESDAY MORNING...BEFORE WARM
FRONTAL ACTION THICKENS CLOUDS S TO N. NO BIG CHANGE ON OUR
DETERMINISTIC HOURLY POP...INCREASING RAPIDLY LATE TUESDAY ACROSS
THE S. LEFT A SLIGHT CHANCE OF AN EMBEDDED T WITH THE LIFT TUESDAY
NIGHT ACROSS THE LOWLAND COUNTIES.
TRIMMED OUR WINTRY MIX PRECIPITATION TO ONLY POCAHONTAS AND EASTERN
RANDOLPH COUNTY OVERNIGHT TUESDAY NIGHT. CURRENTLY THINKING MAX ICE
WOULD BE NEAR A QUARTER OF AN INCH. ALSO TRY TO END THAT THREAT A
FEW HOURS EARLIER AROUND DAWN WEDNESDAY.
OVERALL...TRIED TO QUICKEN THE PACE OF THE SENSIBLE WEATHER WITH
THIS DEEPENING LOW PRESSURE. BROUGHT A BRIEF DRY SLOT UP INTO THE
WESTERN LOWLAND SOONER...WITH POPS DROPPING OFF BEFORE DAWN
WEDNESDAY ACROSS THE WESTERN LOWLANDS...BEFORE INCREASING AGAIN
DURING THE DAY ON WEDNESDAY WITH THE FRONTAL PASSAGE.
HAVE 2 NON DIURNAL HOURLY TEMPERATURE TRACES...WHICH IS ALWAYS FUN
TO FIGURE. HAVE MINIMUM TEMPERATURES TUESDAY NIGHT AROUND 04-05Z...
WITH READINGS INCREASING DURING THE PREDAWN HOURS. HAVE MAXIMUM
TEMPERATURE ON WEDNESDAY AROUND 15/16Z...THEN FALLING DURING THE
AFTERNOON. HAVE TRANSITION TO SNOW SHOWERS AROUND 21Z.
HAVE 2 HAZARDS MENTIONED IN OUR HAZARDOUS WEATHER POTENTIAL. WIND
GUSTS TUESDAY NIGHT INTO WEDNESDAY NIGHT IS FOR THE WHOLE CWA.
FIRST STARTING WITH THE SE FLOW INTO THE HIGHER TERRAIN OF OUR
MOUNTAINOUS COUNTIES TUESDAY NIGHT...THEN ENDING WITH THE SW AND W
FLOW IN WAKE OF FRONT. THE SECOND HAZARD WOULD BE A MUCH MORE
LIMITED AREA IN OUR CWA...THAT BEING THE WINTRY MIX INCLUDING
FREEZING RAIN TUESDAY NIGHT TO AROUND DAWN WEDNESDAY IN THE
AFOREMENTIONED 2 COUNTIES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
STRONG LOW PRESSURE LIFTS RAPIDLY THRU THE GREAT LAKES AND NEW
ENGLAND AT THE START OF THE PERIOD. STRONG COLD ADVECTION RAPIDLY
OVERSPREADS THE ENTIRE AREA WEDNESDAY EVENING...WITH ANY RAIN
SHOWERS CHANGING TO SNOW SHOWERS. DO NOT EXPECT MUCH OF A POST
FRONTAL WRAPAROUND SNOW EVENT OR EVEN A SIGNIFICANT UPSLOPE EVENT
WEDNESDAY NIGHT. FLOW AROUND THE DEPARTING LOW REMAINS MORE WESTERLY
WITH DEEPER MOISTURE REMAINING TO OUR NORTH. THUS...EXPECT LITTLE OR
NO SNOW ACCUMULATION IN MOST OF THE LOWLANDS...WHILE GENERALLY
LIGHT SNOW ACCUMULATIONS ARE EXPECTED IN THE NORTHERN AND CENTRAL
MOUNTAINS. THE BIGGER FACTOR WEDNESDAY NIGHT MAY BE THE GUSTY WEST
WINDS IN THE TIGHT PRESSURE GRADIENT AROUND THE LOW...ESPECIALLY
OVER SOUTHEAST OHIO AND THE HIGHER ELEVATIONS OF THE NORTHERN
MOUNTAINS. GOING A BIT COLDER THAN MOS GUIDANCE...GIVEN THE STRONG
850/950MB COLD ADVECTION.
FOR THURSDAY...HIGH PRESSURE BUILDS IN WITH LINGERING MOUNTAIN SNOW
SHOWERS RAPIDLY ENDING...WITH DECREASING CLOUDS IN THE WEST. HIGH
PRESSURE OVER THE AREA THURSDAY NIGHT WITH IDEAL RADIATIONAL
COOLING...AGAIN GOING BELOW GUIDANCE TEMP MINS.
ANOTHER MUCH WEAKER SYSTEM IN THE STRONG WESTERLY FLOW IS PROGGED TO
PASS SOUTH OF OUR AREA AROUND THE BEGINNING OF THE WEEKEND. GOING
WITH THE FASTER AND MORE SUPPRESSED GFS...WHICH MAY GIVE THE AREA A
LIGHT RAIN OR SNOW EVENT LATER FRIDAY NIGHT INTO SATURDAY
MORNING.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
06Z MONDAY THROUGH 06Z TUESDAY...
MAINLY VFR CONDITIONS EXPECTED TONIGHT WITH ONLY SCATTERED TO BROKEN
HIGH CLOUDS. SOME PATCHY MVFR FOG IS POSSIBLE...ESPECIALLY NEAR
KEKN...BUT NO WIDESPREAD RESTRICTIONS TO VSBY ARE EXPECTED. VFR
CONDITIONS WILL CONTINUE ON MONDAY...ALTHOUGH CEILINGS WILL THICKEN
AND LOWER AS A WEAK FRONT APPROACHES THE REGION. THIS WILL GENERATE
LIGHT RAIN SHOWERS ON MONDAY...CHANGING TO SNOW OR A RAIN/SNOW MIX
AFTER 21Z...MAINLY OVER THE HIGHER TERRAIN. LIGHT SE SURFACE WINDS
WILL VEER DURING THE DAY MONDAY AS THE WEAK FRONTAL BOUNDARY
APPROACHES THE REGION. MODERATE TO STRONG WESTERLY WINDS ALOFT.
AFTER 06Z TUESDAY...
IFR IN MOSTLY RAIN LATE TUESDAY INTO WEDNESDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...KTB/CL/JMV
NEAR TERM...CL/MDP
SHORT TERM...KTB
LONG TERM...JMV
AVIATION...SL
