855 
FXUS61 KRLX 090541
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
1241 AM EST TUE MAR 9 2010

.SYNOPSIS...
HIGH PRESSURE INTO TUESDAY. WARM FRONT ALOFT PASSES TUESDAY NIGHT. 
UPPER SYSTEM BRINGS RAIN CHANCES LATER THIS WEEK...WHICH ALONG WITH 
MELTING SNOW MAY LEAD TO FLOODING PROBLEMS IN THE WV MOUNTAINS.

&&

.NEAR TERM /THROUGH TODAY/...
A QUIET PERIOD AS HIGH PRESSURE MOVES ACROSS TONIGHT. ALTHOUGH 
MODELS KEEP SOME LOW LEVEL MOISTURE AROUND TONIGHT...LACK OF AN 
INVERSION ALOFT ON FORECAST ATMOSPHERIC SOUNDINGS SUGGEST NO CLOUD 
LAYER FORMING IN MIXING LAYER BENEATH AN INVERSION. ON THE OTHER 
HAND...IDEAL RADIATIONAL COOLING CONDITIONS WITH MOSTLY CLEAR 
SKIES...LIGHT WINDS AND DRY AIR...SUGGEST A WIDE RANGE IN 
TEMPERATURES FROM PROTECTED VALLEYS TO RIDGETOPS...ESPECIALLY IN THE 
NORTHERN WEST VIRGINIA MOUNTAINS. PLAYING DOWN FOG FORMATION IN MOST 
AREAS TONIGHT GIVEN THAT THE AIR IS STILL QUITE DRY. LEANING TO THE 
MAV TEMPERATURE GUIDANCE TONIGHT...FEELING THIS BEST SHOWS THE 
DIURNAL FACTOR.

FOR TUESDAY...THE FIRST IMPULSE FROM THE LARGE CLOSED SYSTEM IN THE 
PLAINS APPROACHES OUR REGION. THIS WILL BRING HIGH AND MID CLOUDS 
QUITE RAPIDLY ACROSS THE REGION FROM THE SOUTHWEST TUESDAY 
AFTERNOON. HOWEVER...WILL KEEP POPS ON THE LOW SIDE AND CONFINED 
MAINLY TO OUR FAR WESTERN ZONES OF NORTHEAST KENTUCKY AND SOUTHEAST 
OHIO QUITE LATE IN THE DAY AS THIS IMPULSE WILL MAINLY GO INTO 
SATURATING THE COLUMN OF AIR. INCREASING CLOUDS AND STILL WEAK 
SOUTHERLY FLOW WILL TEND TO HOLD TEMPS DOWN A BIT...BUT STILL A BIT 
MILDER THAN TODAY.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
WARM FRONT PUSHES IN EARLY TUESDAY NIGHT WITH SHOWERS ALONG THE 
BOUNDARY. WARM SECTOR BRINGS DEWPOINTS UP TO THE 40S BY THURSDAY 
WITH SOME INCREASES IN THE SOUTHEAST SURFACE WIND AS THE PRESSURE 
GRADIENT TIGHTENS UP AND FLOW ALOFT INCREASES. THIS WILL SPEED UP 
THE MELT ACROSS THE MOUNTAINS...AND WILL BE EXACERBATED BY THE RAIN 
IN THE WARM SECTOR AND WITH THE SECONDARY WARM FRONT WITH A NEW 
SURFACE LOW ROTATING INTO THE UPPER MIDWEST. WILL BE PAYING VERY 
CLOSE ATTENTION TO THE RATE OF THE SNOW MELT AND THE REACTION OF THE 
AREA STREAMS...CREEKS...AND RIVERS IN THE HIGHER ELEVATIONS.

CHANCES FOR SHOWERS WILL EXIST BEHIND THE FIRST WARM FRONT IN 
SOUTHWESTERLY FLOW ALOFT. INSTABILITY LOOKS TO BE VERY LIMITED...IF 
EXISTENT AT ALL...AND DESPITE 500HPA TEMPERATURES BEING VERY 
COLD...LIFTED INDICES DO NOT SUPPORT THUNDER WITH THESE BOUNDARIES. 
BREAKS IN THE CLOUDS WILL BE HARD TO COME BY IN THIS SYNOPTIC SETUP. 

THICKNESSES INCREASING BEYOND 500DKM WILL ALLOW FOR ABOVE NORMAL 
HIGH TEMPERATURES ACROSS THE LOWLANDS. AS STATED YESTERDAY...WILL 
NOT GET TOO MUCH IN THE WAY OF CONTRIBUTION FROM SOLAR 
INSOLATION...AND WARM AIR ADVECTION WILL NOT BE OVERLY STRONG. 
TEMPERATURE RISES WILL BE MORE OF THE RESULT OF UPPER LEVEL RIDGING 
AHEAD OF THE DEEP LOW ENCOMPASSING THE MAJORITY OF THE GREAT PLAINS.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
MAIN CONCERN DURING THIS PERIOD IS FOR FLOODING POTENTIAL IN THE 
CENTRAL TO ESPECIALLY NORTHERN WV MOUNTAINS THURSDAY-FRIDAY...WITH 
RAMIFICATIONS BEYOND THEN AS THE WATER DRAINS INTO MAIN STEM RIVERS. 
SEE DETAILS IN THE HYDROLOGY SECTION.

GFS AND ECMWF AGREE THAT AREA IS FIRMLY IN THE WARM SECTOR BY 
THURSDAY NIGHT...WITH COLD FRONT SET TO PASS THROUGH SOMETIME LATER 
FRIDAY/FRIDAY NIGHT. AHEAD OF THAT FRONT...A DECENT LOW LEVEL JET 
MAINTAINS A WARM AND MOIST SOUTHERLY FLOW. FOR THIS TIME OF YEAR...A 
FAIR AMOUNT OF INSTABILITY APPEARS TO DEVELOP BEFORE THE COLD FRONT 
MOVES THROUGH. CHANCE OF THUNDERSTORMS WAS THUS ADDED TO ACCOMPANY 
LIKELIHOOD OF RAINFALL. BEHIND FRONT OVER THE WEEKEND...UPPER LOW 
SLOWLY TRUDGES OVER THE REGION...KEEPING SHOWERY WEATHER IN THE 
AREA. HOWEVER...THIS UPPER LOW IS NOT VERY COLD COMPARED TO OTHERS 
OF RECENT WEEKS...SO AFTER OUR WARM FRIDAY...TEMPERATURES WILL 
REMAIN AT LEAST NEAR NORMAL OVER THE WEEKEND. HPC FORECAST FOLLOWS 
THESE IDEAS AND WAS USED AS THE BASIS FOR OUR FORECAST GRIDS.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
06Z TUESDAY THROUGH 06Z WEDNESDAY...
VFR CONDITIONS THE RULE FOR MOST THROUGH THIS AFTN. EXCEPTION
BEING SOME OF THE MORE PROTECTED VALLEYS WHERE MVFR VIS IN FG
POSSIBLE ARND DAWN THIS MORNING...INCLUDING KEKN...WHERE BRIEF IFR
VIS POSSIBLE. WARM FRNT WILL DEVELOP ACROSS LOWER OH VALLEY INTO
TN VALLEY THIS AFTN. CEILINGS WILL GRADUALLY LOWER HEADING INTO THE
EVE HRS. WARM FRNT WILL CROSS FROM SW TO NE FRM 03Z-09Z WED WITH
BKN LINE OF SHRA...PRODUCING MVFR CONDITIONS FOR MOST.

AFTER 06Z WEDNESDAY...
NO WIDESPREAD IFR CONDITIONS EXPECTED.

&&

.HYDROLOGY...
DURING RECENT DAYS...MELTING SNOW BY DAY HAS BEEN BALANCED BY BELOW 
FREEZING TEMPERATURES AT NIGHT FOR THE MOUNTAINS. HOWEVER...FROM 
TUESDAY ONWARD...WATER WILL BE RELEASED FROM THE SNOWPACK AROUND THE 
CLOCK THROUGH THE END OF THE WEEK...WITH TEMPERATURES STAYING ABOVE 
FREEZING EVEN AT NIGHT. A MILD SOUTHEAST WIND WILL SET UP AGAINST 
THE MOUNTAINS BY THURSDAY...WITH DEWPOINTS MAINLY IN THE LOWER TO 
MID 40S IN THE MOUNTAINS THROUGH FRIDAY. THUS...THE MOUNTAIN 
SNOWPACK THAT IS LEFT THEN WILL UNDERGO RAPID MELTING DURING THE 
THURSDAY-FRIDAY PERIOD. AT THE SAME TIME...A LARGE LOW PRESSURE 
SYSTEM TO OUR WEST...WILL CAUSE INCREASING RAIN CHANCES. THIS 
COMBINATION OF FACTORS POSES A POTENTIALLY SIGNIFICANT RISK OF 
FLOODING IN THE CENTRAL AND ESPECIALLY NORTHERN WV MOUNTAINS. THIS 
POTENTIAL WILL CONTINUED TO BE ASSESSED...AND MAY RESULT IN FLOOD 
WATCHES FOR THE MOST PRONE AREAS. UNTIL THEN...WATER LEVELS CAN BE 
EXPECTED TO BE GRADUALLY RISING WITH TIME FROM SNOWMELT. AT THIS 
TIME...THE FOLLOWING RIVERS APPEAR TO BE THE MOST VULNERABLE TO 
FLOODING FROM THURSDAY ONWARD...TYGART...CHEAT...GREENBRIER...UPPER 
ELK...AND UPPER GAULEY. GETTING INTO NEXT WEEKEND AND BEYOND...WE 
WILL HAVE TO MONITOR POTENTIAL IMPACT OF THE SNOWMELT AND RAIN 
EVENTUALLY DRAINING INTO THE OHIO RIVER.

&&

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

&&

$$
SYNOPSIS...26/MDP/JMV
NEAR TERM...JMV
SHORT TERM...26
LONG TERM...MDP
AVIATION...30
HYDROLOGY...MDP