FXUS61 KLWX 230216 AAB
AFDLWX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
916 PM EST SUN NOV 22 2009

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO RETREAT TO THE NORTH TONIGHT WHILE AN 
AREA OF LOW PRESSURE DEVELOPS OFF THE SOUTHEAST COAST. THIS LOW WILL 
TRACK UP THE MID-ATLANTIC COAST MONDAY AND TOWARDS NEW ENGLAND 
MONDAY NIGHT INTO TUESDAY. HIGH PRESSURE WILL BUILD IN BEHIND THIS 
SYSTEM LATER TUESDAY AND WEDNESDAY. A COLD FRONT WILL PASS THROUGH 
THURSDAY BRINGING UNSETTLED CONDITIONS. AN UPPER-LEVEL LOW WILL 
CONTINUE TO IMPACT THE REGION LATE IN THE WEEK.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
OVERALL SYNOPTIC EVOLUTION STILL ON TRACK FROM PREV FCST.
ISENTROPIC LIFT INCRS TNGT...WITH LOW-LVL CLD CVR XPCD TO SPREAD
ACRS FCST AREA LATE. RAIN WILL CONT TO SPREAD NWD AS MID-LVL
SHRTWV TROF APRCHS...BUT WILL ONLY ENCROACH UPON SRN ZONES THRU
TNGT. MODEL TRENDS HAVE BEEN TO SLOW ARRIVAL OF PCPN...AND THIS
TREND WAS FOLLOWED FOR THE EVE UPDATE. HAVE TRIMMED NRN EDGE OF
POPS DOWNWARD THRU TNGT. PREV DISCUSSION FOLLOWS...

CURRENT ANALYSIS SHOWS HIGH PRESSURE CENTERED OVER NEW ENGLAND THIS 
AFTERNOON. A SURFACE LOW CONTINUES TO TRACK ALONG THE GULF COAST 
STATES. THE UPPER-LEVEL LOW ASSOCIATED WITH THE SURFACE LOW IS 
TRACKING TOWARD THE TENNESSEE VALLEY.  

SURFACE HIGH WILL CONTINUE TO RETREAT TO THE NORTHEAST TONIGHT WHILE 
THE SURFACE LOW REDEVELOPS ALONG THE SOUTHEAST COAST. THE 
UPPER-LEVEL LOW ASSOCIATED WITH THIS SYSTEM WILL TRACK THROUGH THE 
TENNESSEE VALLEY TONIGHT AND TOWARD SOUTHWESTERN VIRGINIA BY MONDAY 
MORNING. 

A LOW-LEVEL EAST-SOUTHEAST FLOW AROUND THE DEPARTING HIGH AND THE 
LOW PRESSURE SYSTEM WILL BRING INCREASING AMOUNTS OF MOISTURE OFF 
THE ATLANTIC OCEAN. THE MOISTURE INCREASE COMBINED WITH ISENTROPIC 
LIFT WILL RESULT IN INCREASING LOW CLOUDS LATER THIS EVENING INTO 
THE OVERNIGHT HOURS. WITH THE ACTUAL STORM SYSTEM REMAINING WELL TO 
THE SOUTH...DRY CONDITIONS ARE EXPECTED THROUGH THIS EVENING. 
HOWEVER...RAIN AHEAD OF THE STORM SYSTEM WILL BEGIN TO OVERSPREAD 
THE REGION FROM SOUTH TO NORTH LATE.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
RAIN WILL SPREAD NWD THRU FCST AREA DURG MID-LATE MRNG.
CATEGORICAL POPS LOOK REASONABLE STILL FOR TMW AFTN AND WERE
RETAINED...ALTHO IT APPEARS THAT ACCUMULATIONS WILL BE SLGTLY
HIGHER WITH EWD EXTENT CLOSER TO XPCD PATH OF SHRTWV TROF. PREV
DISCUSSION FOLLOWS...

THE SURFACE LOW WILL CONTINUE TO TRACK UP THE MID-
ATLANTIC COAST WHILE THE UPPER-LEVEL LOW SHEARS APART AS IT TRACKS
ACROSS OUR REGION. A LOW-LEVEL EASTERLY FLOW COMBINED WITH
ISENTROPIC LIFT WILL RESULT IN LOW CLOUDS ALONG WITH OCCASIONAL
RAIN. RAINFALL AMOUNTS SHOULD BE ON THE LIGHT SIDE DUE TO THE LACK
OF STRONG DYNAMICS WITH THIS SYSTEM. MAX TEMPS WILL BE SEVERAL
DEGREES COOLER THAN RECENT DAYS DUE TO THE RAINFALL...RANGING FROM
THE MID AND UPPER 40S ACROSS THE POTOMAC HIGHLANDS INTO THE
SHENANDOAH VALLEY...TO NEAR 50 IN WASHINGTON AND BALTIMORE...TO
THE LOWER AND MIDDLE 50S ACROSS LOWER SOUTHERN MARYLAND.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
ANY PCPN LINGERING MON NGT WUD BE AS A RSLT OF THE DEF AXIS ACRS 
CWFA. HWVR...LOPRES RATHER WEAK...AND FAR OFFSHORE...SO DONT THINK 
THAT PCPN WUD BE PLENTIFUL. WUD BE MORE CONCERNED ABT DZ...BUT SFC 
WNDS NLY NOT NE/ELY.

HIPRES BRIEFLY BLDS TUE-TUE NGT. BUT IT SHUD BE A DIRTY RDG AS AMPLE 
LLVL MSTR STILL LINGERS. SUNSHN SHUD BE LMTD...ASSUMING IT CAN BRK 
THRU MARINE STRATUS. BASED ON TKNS OF MARINE DECK ON MDL 
TIME-HGTS...THAT/LL BE A BIG ASSUMPTION. SUSPECT LLVL CLDS WL BE 
SUFFICIENT FOR DZ TO DVLP TUE NGT...SPCLY SINCE SFC HIGH WEDGED A LA 
CAD AND H9-8 FLOW BCMG SLY.

CMPLX SCENARIO SETTING UP FOR MID WK...AS S/WV ENERGY DROPS INTO 
CNTRL PLAINS...CUTTING OFF H5 LOW BY TUE. ADDTL VORTS CARVE OUT A 
2ND LOW...WHICH WL DEEPEN LOW OVR GRTLKS BY THU. LCLLY...CWFA WL 
RECEIVE ISENT LIFT...THEN GLANCING BLOW OF PVA WED. THUS...CLDS 
GOING NOWHERE...AND CHC SHRA RETURNS. SOME MIXING CUD PUNCH HOLES IN 
THE CLD DECK BHD VORT LT WED-WED NGT. 

TEMPS FAIRLY TEMPERATE THRU THE PD. NOT MUCH SPREAD IN MOS TEMPS 
TMRW NGT-TUE...AND A SLGTLY LRGR SPREAD TUE NGT. CONSIDERING 
CLDS...STAYED AWAY FM BIG DIURNAL SWINGS-- WARM SIDE OF MEAN FOR 
MIN-T BUT COOLER SIDE FOR MAXT.

XTNDD...DP H5 TROF AXIS/CUTOFF LOW TO PIVOT ACRS CWFA THU-FRI. THIS 
CYCLE...GDNC - SPCLY GFS - NOW TRANSFERRING ENERGY TO DVLPG CSTL 
SYSTM LT THU NGT-ELY FRI MRNG. BUT EVEN THE MORE STBL ECMWF TRENDING 
TWD GFS. EITHER WAY THE END RSLT WL BE SIMLR...FVRBL SUPPORT FOR 
PCPN...AND SIGNALS THAT HIER ELEVS CUD RECEIVE SNW. WL INCR POPS 
THU-THU NGT...AND STICK W/ MTN SNW/MIX ONCE CAA UPON US THU PM. NW 
FLOW PTTN THRU SAT. WL ENHANCE UPSPL PCPN THRU THAT TIME.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
CIGS AOB 1.0 KFT XPCD TNGT AS ISENTROPIC LIFT INCRS ACRS RGN.
VSBYS ALSO XPCD TO DROP TO IFR-MVFR THRESHOLDS AS FOG DVLPS THIS
EVE. ONSET OF DRZL XPCD LATE TNGT...WITH RAIN MOVG NWD INTO SRN
PORTIONS OF FCST AREA BY 08-10 UTC. DRZL CONTS ACRS NRN TERMINALS
THRU MRNG UNTIL RAIN ARRIVES AT ALL TERMINALS DURG LATE MRNG.
RESTRICTIONS XPCD TO CONT THRU AT LEAST MON EVE.
 
FLGT RESTRICTIONS PSBL THRU MUCH OF WK AS UNSTTLD CONDS ABOUND. IF 
THERE WERE A BRK IT WUD COME TUE AFTN/EVE...BUT LOW CLDS/DZ LKLY TO 
RTN TUE NGT.

&&

.MARINE...
PRESSURE GRADIENT APPEARS TO BE SHARPENING SLGTLY EARLIER THAN
DEPICTED IN PREV GRIDS...MAINLY LWR PORTIONS OF MD CHSPK BAY AND
LWR TIDAL POTOMAC. HAVE ADJUSTED START TIME OF SMALL CRAFT ADZY TO
PRESENT TIME FOR THESE ZONES..WHERE 17-20 KT GUSTS COMMON AND XPCD
TO PERSIST. RMNDR OF ADZY WILL BGN AT MIDNIGHT AS PREVLY ISSUED.
PREV DISCUSSION FOLLOWS...

LOW PRESSURE WILL DEVELOP OFF THE SOUTHEAST COAST TONIGHT. A
STRENGTHENING PRESSURE GRADIENT DUE TO THE LOW WILL BRING SCA WIND
GUSTS ACROSS THE CHESAPEAKE BAY AND LOWER TIDAL POTOMAC OVERNIGHT.
AS LOW PRESSURE TRACKS UP THE MID- ATLANTIC COAST MONDAY...MORE
SCA CONDITIONS ARE EXPECTED ACROSS THE LOWER TIDAL POTOMAC AND
CHESAPEAKE BAY. HAVE CAPPED WIND GUSTS MONDAY AROUND 15 KNOTS
ACROSS THE UPPER TIDAL POTOMAC...BUT WITH FASTER WINDS LESS THAN A
THOUSAND FEET FROM THE SURFACE...ANY MIXING WOULD BRING STRONGER
WIND GUSTS LATER MONDAY MORNING/AFTERNOON. THIS WILL HAVE TO BE
MONITORED BY LATER SHIFTS.

G20KT LKLY TO CONT INTO TMRW NGT DUE TO NLY FLOW...SPCLY FOR MAIN 
CHANNEL BAY BLO POOLES ISL AND FOR LWR PTMC. WL INCL BIG INLETS BUT 
NOT BALT HARBOR/PAX RIVER. HIPRES RDG SHUD DECR WNDS TUE-WED...ALTHO 
LOW CLDS SHUD BE PLENTIFUL AND RA A PSBLTY BY WED.

&&

.TIDES/COASTAL FLOODING...
WITH HIGH PRESSURE WELL TO OUR NORTH...AN ONSHORE FLOW HAS DEVELOPED 
THIS AFTERNOON. THE FLOW IS WEAK AND TIDAL ANOMALIES RANGE FROM NEAR 
NORMAL TO ABOUT ONE HALF FOOT ABOVE NORMAL. LOW PRESSURE IS EXPECTED 
TO DEVELOP OFF THE SOUTHEAST COAST TONIGHT AND THE GRADIENT IS 
EXPECTED TO TIGHTEN BETWEEN THESE TWO SYSTEMS OVERNIGHT AND MONDAY. 

AS THE LOW TRACKS UP THE MID-ATLANTIC COAST MONDAY INTO MONDAY 
NIGHT...THIS WILL CAUSE TIDAL ANOMALIES TO INCREASE DURING THIS 
TIME. LATEST CBOFS AND EXTRATROPICAL MODELS CONTINUE TO INDICATE 
THAT WATER LEVELS WILL REMAIN BELOW THRESHOLDS FOR MINOR COASTAL 
FLOODING. THE ASTRONOMICAL NORMS FOR WATER LEVELS ARE ALSO ON THE 
LOWER SIDE DUE TO THE LUNAR CYCLE APPROACHING THE FIRST QUARTER 
PHASE. HAVE NOT ISSUED AN ADVISORY FOR THESE TWO REASONS...BUT THIS  
WILL HAVE TO BE MONITORED BY LATER SHIFTS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 5 AM EST TUESDAY 
     FOR ANZ531>533-539>541.
     SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 8 PM EST MONDAY 
     FOR ANZ530-538-542.
     SMALL CRAFT ADVISORY UNTIL 5 AM EST TUESDAY FOR ANZ534-537-543.

&&

$$

UPDATE...KRAMAR
PREV DISCUSSION...KRAMAR/LASORSA/HTS