000
FXUS61 KLWX 150751
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
351 AM EDT WED MAY 15 2013

.SYNOPSIS...
A FRONTAL BOUNDARY WILL APPROACH FROM PENNSYLVANIA LATE TODAY AND
STALL OUT OVER THE SOUTHERN MID-ATLANTIC THROUGH THE END OF THE
WEEK AND INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
THE CONVEYOR BELT OF ISOLATED SHOWERS CONTINUES OVER THE NERN
QUADRANT OF THE CWA...A STEADY STREAM OF SPRINKLES COMING OUT OF MID
CLOUD DECKS. BUT THE MAIN STORY OF THE NEAR TERM IS THE
TEMPERATURES. WE`RE NOW A SOLID 10-15 DEG ABOVE CONDITIONS AT THIS
TIME 24 HRS AGO. THIS DIFFERENCE WILL CARRY OVER AND EVEN MORE SO
INTO THE AFTN HRS TODAY...AS WE PEAK WELL INTO THE 80S ACROSS MUCH
OF THE REGION.

A RELATIVELY SMALL BUT VERY STRONG UPPER RIDGE CENTERED OVER THE NRN
PLAINS DEVELOPED A LOCALIZED AREA OF TEMPS IN THE UPPER 90S/L100S
YESTERDAY AFTN. AT THE SAME TIME NEAR TRIPLE-DIGIT HEAT WAS
OCCURRING...ONLY A FEW HUNDRED MILES TO THE EAST - OVER THE GREAT
LAKES - TEMPS WERE ONLY THE 50S. IN BETWEEN THESE AREAS RESIDES A
HIGHWAY OF FAST UPPER FLOW CREATED BY THESE STRONG OPPOSING FORCES.
A PIECE OF THIS ENERGY FROM THE WEST WILL BE FORCED TOWARD THE AREA
TODAY.

A COMPLEX SFC SCENARIO W/ ALL THESE POTENT BUT SMALL SCALE FEATURES
MOVING ABOUT THE NRN HALF OF THE COUNTRY TODAY. A WARM FRONT HAS
BEEN FORMING ALONG THE I-70 CORRIDOR OF THE UPPER MIDWEST...
STRETCHING HUNDREDS OF MILES AND WILL EVENTUALLY BECOME A WX-MAKER
FOR THE AREA BEGINNING LATE TONIGHT AND INTO EARLY FRI. FOR
TODAY...A COLD FRONT DRIFTING DOWN FROM THE SYSTEM THAT BROUGHT COOL
TEMPS TO THE GREAT LAKES YESTERDAY WILL STAY WELL TO THE NORTH BUT
JOIN UP W/ THE WARM FRONT AND BECOME A PSEUDO-STATIONARY BOUNDARY
NEAR THE MASON-DIXON LINE OVERNIGHT.

LOCAL GUIDANCE LIKE THE HRRR AND GFS-BASED WRF MODELS TAKING THE
ACTIVITY CURRENTLY OVER THE LAKE ERIE REGION...SPILLING IT OVER INTO
THE ERN HALF OF THE CWA LATER THIS MRNG AND EARLY AFTN. PLACED AN
ISOLATED/SCATTERED POP FOR THESE AREAS...DRYING OUT AND CLEARING OUT
DURING THE AFTN. A QUICK RETURN TO THE CLOUDS AND PRECIP ALONG THE
MASON-DIXON LINE LATE THIS AFTN THOUGH...AS HI-RES MODELS CONTINUING
TO DEPICT A DEVELOPMENT OF CONVECTION JUST TO OUR NORTH -
POTENTIALLY DRIFTING ESE INTO THE NRN TIER COUNTIES TOWARD LATE
EVE...DISSIPATING OVERNIGHT BEFORE HEADING TOO FAR SOUTH.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
FRONTAL BOUNDARY IS FORECAST TO SINK SOUTHWARD ACROSS THE SOUTHERN
MID-ATLANTIC THROUGH THE END OF THE WEEK...POSSIBLY SNAKING BACK UP
THE APPALACHIANS ON FRIDAY. WITH FRONTAL BOUNDARY OVER THE CWA ON
THURSDAY...WILL CONTINUE WITH CHANCE POPS MAINLY IN THE
AFTERNOON/EVENING WITH MAXIMA IN THE LOWER TO MID 80S.

WITH FRONT SAGGING A LITTLE FURTHER SOUTH INTO FRIDAY...WILL FOCUS
POPS ACROSS THE SOUTHERN HALF ON THE CWA WITH MAXIMA POSSIBLY A
COUPLE OF DEGREES LOWER.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
FRONTAL BOUNDARY IS FORECAST TO REMAIN SOUTH OF THE AREA OVER THE
WEEKEND...THEN LIFTS BACK NORTH AS A WARM FRONT EARLY NEXT WEEK IN
ADVANCE OF THE NEXT SHORTWAVE. FEW ADJUSTMENTS WERE MADE TO THE
FORECAST WHICH INCLUDE CHANCE POPS THROUGH MUCH OF THE PERIOD.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
LITTLE HAS CHANGED IN TERMS OF THE SOLID 7-8KFT DECK OVER THE METRO
DC/BALT AREAS AND EVEN A FEW INTERMITTENT SPRINKLES ALONG THE WAY.
THIS WILL CONTINUE THRU DAWN AND POSSIBLY INTO THE LATE MRNG HRS
ACROSS A PORTION OF NERN MD. THIS ACTIVITY IS EXPECTED TO DISSIPATE
AND RECEDE TO THE NORTH DURING THE AFTN HRS...AS SLY WINDS PICK UP
INTO THE G20-25KT RANGE. MID DECKS WILL RETURN FROM THE NORTH LATE
THIS EVE...BUT MAINLY TO THE NORTH OF THE I-66 CORRIDOR W/ SOLID VFR
CONDITIONS THRU THE TAF PERIOD.

FRONTAL BOUNDARY IS FORECAST TO STALL OUT TO THE SOUTH OF THE AREA
DURING THE LATE WEEK-WEEKEND PERIOD. WITH BOUNDARY FAIRLY
CLOSE...CONVECTION IS POSSIBLE MAINLY IN THE AFTERNOON/EVENING EACH
DAY.

&&

.MARINE...
SLY CHANNELING CONTINUES OVERNIGHT AND WILL CONTINUE TO SLOWLY BUILD
W/ OBS HOVERING IN THE LOW-END SCA RANGE. THESE CONDITIONS WILL
SPREAD FURTHER NORTH INTO THE MRNG HRS...AND OVER THE TP RVR BY LATE
MRNG. THE AFTN HRS WILL SEE THE HIGHER SYNOPTIC GUSTS THIS AFTN...W/
MOST AREAS IN SOLID SCA RANGE AND A FEW GUSTS IN THE U20KT RANGE
BEFORE SUNSET. A FEW ISOLATED SHOWERS WILL ALSO CONTINUE THIS
MRNG...AND AGAIN ANOTHER ROUND OVER THE NRN BAY LATE TONIGHT.

FRONTAL BOUNDARY SLIPS SOUTH OF THE WATERS LATE WEEK AND REMAINS
SOUTH THROUGH THE WEEKEND. GRADIENT IS EXPECTED TO REMAIN FAIRLY
WEAK THROUGH THE PERIOD. AS WINDS BECOME SOUTHEAST OVER THE
WEEKEND...WINDS MAY CREEP UP CLOSE TO SCA LEVELS OVER PORTIONS OF
THE WATERS.

&&

.TIDES/COASTAL FLOODING...
THE SLY CHANNELING OF WINDS UP THE MAIN STEM OF THE BAY HAS
INCREASED POSITIVE TIDAL ANOMALIES TOWARD THE 1 FT ABOVE MARK BUT
STILL CLOSER TO 3/4FT ATTM. WATER LEVEL MODEL GUIDANCE KEEPING
ANNAPOLIS UNDER MINOR THRESHOLDS FOR THE UPCOMING H.T. CYCLE WHICH
WILL BE THE MOST SENSITIVE AND BEST CHANCE FOR MINOR TIDAL
FLOODING IN THE NEAR TERM. WINDS WILL CONTINUE TO GUST OUT OF THE
SOUTH FOR MUCH OF THE DAY...BEFORE A COLD FRONT ARRIVES LATE
TONIGHT AND BEGINS TO TAPER OFF THESE WINDS AND CHANGE DIRECTIONS
TO MORE WLY AND CAUSE LEVELS TO DROP AGAIN.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ531>534-
     537-539>541-543.
     SMALL CRAFT ADVISORY FROM NOON TODAY TO 8 PM EDT THIS EVENING
     FOR ANZ530-535-536-538-542.

&&

$$
SYNOPSIS...GMS/BPP
NEAR TERM...GMS
SHORT TERM...BPP
LONG TERM...BPP
AVIATION...GMS/BPP
MARINE...GMS/BPP
TIDES/COASTAL FLOODING...GMS