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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
914 AM EST WED MAR 4 2015

.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION TODAY AND TONIGHT. HIGH
PRESSURE BUILDS OVERHEAD FRIDAY...THEN PERSISTS THROUGH THE
WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SFC ANALY DEPICTS A CPL OF BNDRYS IN THE PRES FIELDS THIS MRNG.
THE FIRST ONE RUNS FM BALT/DC TO CHO...THEN HEADS WSWWD ACRS TN TO
ARKANSAS. THIS BNDRY HAS LLVL THERMAL SUPPORT. THE LATTER
STRETCHES ACRS NW PA AND NRN OH. THE UPR JET DYNAMICS LIE HERE. 

REGIONAL RADAR THIS MORNING ALREADY SHOWS THE DYNAMICAL...HIGH 
MOISTURE CONTENT FRONTAL ZONE SAGGING OUR WAY. THERES PLENTY OF
MSTR W OF THE APLCNS ATTM...AND WL NEED TO MONITOR HOW MUCH OF
THIS CAN HOP THE MTNS.

IN SHORT...TODAY WILL FEATURE OCCASIONAL ROUNDS OF RAIN...MOST 
PREVALENT ACROSS THE NORTHERN HALF OF THE CWA. WILL KEEP AN EYE ON 
RAIN TOTALS...ESPECIALLY IN THE HIGHLANDS WHERE TEMPERATURES HAVE 
WARMED AND THE HEAVIEST RAIN WILL FALL. 

IN-SITU WEDGE WILL HOLD TEMPERATURES IN THE 40S ACROSS MUCH OF
AREA. GOING FCST HAS GOOD LAMP SUPPORT. NO TEMP CHGS ANTICIPATED
ATTM.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
SYNOPTIC PTTN FM LTST GDNC RUNS SEEM TO BE SIMLR TO THOSE YDA.
ONLY ADJUSTMENTS BASED ON SUBTLE THERMAL DIFFS. KEY FACTORS ARE A
SLGTLY SLOWER TIMING AND HIER QPF VALUE. BASED ON THAT...THE
MIDNIGHT SHIFT TRANSITIONED THE WINTER STORM WATCH TO A WARNING
FOR MOST OF THE CWFA. THE SRN FRINGE OF THE AREA IS THE EXCEPTION
DUE TO A LONGER PD OF TIME IN RAIN AND SLEET.

THE BNDRYS /MDL GDNC DOESNT DO A GOOD JOB DISTINCTLY RESOLVING
BOTH OF THEM/ WL CONT SLIDE SWD TNGT...ALLOWING THE ARCTIC AMS FM
THE GRTLKS TO OVERSPREAD THE AREA. MEANWHILE...A SATD MSTR STREAM
WL CONT SPREADING ENEWD...OVERRIDING THE COLDER AMS. DYNAMICS WL
BE FUELED BY THE RRQ OF THE UPR JETMAX AS WELL AS LLVL
BAROCLINICITY. ALL OF THIS SUPPORTS A TRANSITION FM RA TO PL AND
THEN TO SNW. 

FCST BASED ON AN ENSEMBLE APPROACH...WHICH SUGGESTS A PD OF FVRBL
DENDRITIC GROWTH AS WELL AS FGEN FORCING IN A CORRIDOR BHD THE
SN/PL TRANSITION. THATS THE JUSTIFICATION FOR RAISING SNW TTLS
ACRS N-CENTRAL MD/ERN WVA/NRN SHEN VLY...AS THESE FEATURES WL
COINCIDE W/ SNWFL THE LONGEST. SUFFICIENT COLD AIR TO SUPPORT SNW
WL REACH THE SRN EDGE OF THE CWFA BY AFTN. WL BE MAKING THE
WRNG/ADVY DECISION FOR THE SRNMOST 5 CNTYS ONCE 12Z GDNC ARRIVES.

TAIL END OF SNOW THURSDAY EVENING IS A FEW MORE TENTHS INCH 
FOR SRN MD BEFORE TAPERING OFF. SKIES CLEAR LATE IN THE NIGHT WITH 
HIGH PRESSURE QUICKLY BUILDING OVERHEAD. GUSTY NW FLOW (AROUND 20 
MPH) FOLLOWS THE COLD FRONT. WIND CHILLS REACH ZERO ACROSS THE CWA 
WITH WIND CHILL ADVISORIES LIKELY OVER PORTIONS WEST OF INTERSTATE 
95. AREAS WEST OF INTERSTATE 95 SHOULD DECOUPLE BEFORE SUNRISE WHICH 
WILL ALLOW FOR SINGLE DIGIT MIN TEMPS...TEENS EAST.

SUNNY FRIDAY UNDER HIGH PRESSURE WITH TRANQUIL CONDITIONS AND MAX 
TEMPS MID TO UPR 20S DUE TO LITTLE MIXING AND FRESH SNOW.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
ONE OF THE LONGEST CONSISTENT WARMING PATTERNS IN AWHILE 
SATURDAY THROUGH MIDDLE OF NEXT WEEK AS VERY BROAD EAST COAST TROUGH 
SLOWLY DEAMPLIFIES. WELCOME CALM WEATHER PATTERN AS THE SUBTROPICAL 
RIDGE BUILDS INTO THE SERN CONUS. A FEW DEGREES WARMER ON MAX TEMPS 
EACH DAY IN SWLY FLOW...LOW 40S FOR SATURDAY...50S BY 
MONDAY...60S...MAINLY SOUTH OF DC MONDAY THROUGH WEDNESDAY. 
UNCERTAINTY DUE TO CLOUD COVER IN THE MIDDLE OF NEXT WEEK PREVENTED 
A BOLDER FORECAST OF MID 60S SOUTH/MID 50S NORTH BY WEDNESDAY...AS 
OF NOW IT IS AROUND 60F SOUTH AND AROUND 50 NORTH.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
VFR CONDS PREVALENT ACRS THE TERMINALS ATTM...BUT W/ PATCHES OF
IFR. SOLID FLGT RESTRICTIONS WL ARRIVE FOR THE AFTN PUSH...W/
CONSISTENT AOB IFR COINCIENT W/ A TRANSITION TO SNW AFTR MIDNGT.
AOB IFR SHUD CONT THRU THE DAY THU.

CONDS QUICKLY IMPROVE TO VFR THURSDAY EVENING FROM NW TO SE 
WITH NW GUSTS AROUND 20 KT. SINGLE DIGITS MIN TEMPS THAT NIGHT FOR 
MOST OF THE AREA. HIGH PRESSURE BUILDS OVERHEAD FRIDAY WITH 
VFR/TRANQUIL CONDS. SWLY FLOW AND MORE HIGH PRESSURE THEN THROUGH 
THE WEEKEND.

&&

.MARINE...
ALL WNDS AOB 10 KT ATTM. A TRANSITION TO NNWLY FLOW WL OCCUR LATER
TDA OR TNGT. WNDS WL INCREASE THEREAFTR...W/ SCA CONDS FOER THE
LATTER PART OF THE NGT INTO THU NGT. 

SCA LIKELY TO EXTEND INTO FRIDAY BEFORE HIGH PRESSURE BUILDS
OVERHEAD. HIGH PRESSURE THEN THROUGH THE WEEKEND WITH SWLY FLOW
DEVELOPING FRIDAY NIGHT.

&&

.HYDROLOGY...
THERE HAS BEEN NOTEABLE SNOWMELT ACRS THE AREA THUS FAR. ADD IN
RAINFALL UP TO A HALF-INCH...AND RIVERS IN THE UPR PTMC BASIN HV
EXPERIENCED SGFNT W/IN BANK RISES. STILL DO NOT XPCT FLOODING...
BUT WL CONT TO MONITOR CLOSELY. AT THIS RATE...RAINFALL MAY REACH
1-2 INCHES.

SOME COMPLICATING FACTORS TO KEEP IN MIND...IF THE CHANGEOVER FROM 
RAIN TO WINTRY PRECIP THIS EVENING OCCURS LATER THAN EXPECTED...
CONCERNS MAY BECOME HEIGHTENED. TRENDS HV BEEN SUGGESTING A LATER
CHANGEOVER. ALSO MANY OF OUR AREA STREAMS ARE COVERED WITH ICE OR
EVEN PARTIALLY FROZEN. THESE EFFECTS WILL HAVE TO BE MONITORED FOR
A POTENTIAL ROLE IN AFFECTING RUNOFF.

LASTLY...AS WE SAW WITH THE RECENT RAIN/ICE/MINOR SNOWMELT...ANY 
AMOUNT OF LIQUID PRECIPITATION STANDS A GOOD CHANCE OF CAUSING MINOR 
POOR DRAINAGE FLOODING...AS NORMAL DRAINAGE PATTERNS MAY BE BLOCKED 
BY PLOWED SNOW.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 9 PM EST 
     THURSDAY FOR DCZ001.
MD...WINTER STORM WARNING FROM 7 PM THIS EVENING TO 7 PM EST 
     THURSDAY FOR MDZ003-501-502.
     WINTER STORM WARNING FROM 10 PM THIS EVENING TO 7 PM EST 
     THURSDAY FOR MDZ004>006-011-503>508.
     WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 9 PM EST 
     THURSDAY FOR MDZ013-014-016-018.
     WINTER STORM WATCH FROM LATE TONIGHT THROUGH THURSDAY EVENING 
     FOR MDZ017.
VA...WINTER STORM WARNING FROM 7 PM THIS EVENING TO 7 PM EST 
     THURSDAY FOR VAZ028-503-504.
     WINTER STORM WARNING FROM 10 PM THIS EVENING TO 7 PM EST 
     THURSDAY FOR VAZ025>027-029>031-040-501-505>508.
     WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 9 PM EST 
     THURSDAY FOR VAZ038-039-050>055-502.
     WINTER STORM WATCH FROM LATE TONIGHT THROUGH THURSDAY EVENING 
     FOR VAZ036-037-056-057.
WV...WINTER STORM WARNING FROM 7 PM THIS EVENING TO 7 PM EST 
     THURSDAY FOR WVZ050>052-055-501>506.
     WINTER STORM WARNING FROM 10 PM THIS EVENING TO 7 PM EST 
     THURSDAY FOR WVZ053.
MARINE...SMALL CRAFT ADVISORY FROM 1 AM THURSDAY TO 6 AM EST FRIDAY FOR 
     ANZ530>543.

&&

$$
SYNOPSIS...BAJ/ADS/HTS
NEAR TERM...ADS/HTS
SHORT TERM...HTS/BAJ
LONG TERM...BAJ
AVIATION...HTS/BAJ
MARINE...HTS/BAJ 
HYDROLOGY...HTS/JE

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