Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 010732
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
332 AM EDT SAT NOV 1 2014

.SYNOPSIS...
LOW PRESSURE OVER EASTERN TENNESSEE WILL CROSS SOUTH CAROLINA
TODAY BEFORE STRENGTHENING OFFSHORE WHILE HEADING TOWARDS CAPE COD
TONIGHT AND SUNDAY. HIGH PRESSURE WILL BUILD OVER THE AREA INTO
MONDAY WITH THE NEXT COLD FRONT ARRIVING LATE WEDNESDAY.
&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
S/WV HAS PLUNGED SWD TO ERN TN ATTM PER WATER VAPOR LOOP.
MEANWHILE...A STALLED FRNTL BNDRY CN BE FOUND OFF THE ATLC CST. CWFA
MAINLY IN BTWN THESE TWO SYSTEMS. A FEW SPRINKLES CAN BE FOUND MVG
ONSHORE. OTRW...CLDY BUT DRY CONDS PREVAIL. XPCT THAT TO CHG LATER
TDA AS THE UPR LOW MVS OFF THE SC CST AND INDUCES CYCLOGENESIS.
CONCURRENTLY...A 2ND LOPRES CENTER WL MEANDER NEWD OFF THE DELMARVA
TWD LONG ISLAND/CAPE COD.

ATTM...THERES NOT A LOT OF COLD AIR PRESENT W/IN THE COLUMN...AND
THE TRACK OF THE UPR LOW WL BE KEEPING THE POLAR PLUNGE W OF THE
CWFA TDA. THAT WL BE FURTHER SUPPORTED BY WAA COMING IN FM THE NE
DUE TO THE INITIAL CSTL LOW. THEREFORE...FEEL THAT ALMOST ANY PCPN
WL BE IN THE FORM OF RA TIL THE UPR LOW/VORT HITS THE COAST. UVV WL
BE IMPRVG THRU THE DAY...AGN COURTESY OF THE INIT LOW AND THE
WAA/DEFORMATION IT PROVIDES. PCPN SHUD BE ADVCG FM NE TO SW. HV
PRESERVED AN INFLUENCE FM THE PASSING UPR SYSTEM IN THE SWRN CORNER
OF CWFA TOO...BUT MAY BE ADJUSTING THAT SHORTLY BASED ON LTST
RDR/MDL TRENDS.

ONCE CYCLOGENSIS OCCURS...WNDS WL PICK UP SIGNIFICANTLY. GFS HAS
CONSISTENTLY BEEN SUGGESTING AT 15-20 KT SUSTAINED FLOW BLURDG EWD
DVLPG DURING THE AFTN...AND MEAN MOMENTUM TRANSFER SUGGESTS G25KT.
HV INFUSED THAT DATA INTO GRIDS.

NO BIG CHG TO MAXT FCST. DAYTIME TEMPS WL BE STRUGGLING TO REACH
50F.
&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
THE SYNOPTIC FOCUS FOR THIS PD WL BE FOR A RAPIDLY DEEPENING CYCLONE
PASSING NE OFF HATTERAS. DRY AIR WL WRAP ARND THE BACK SIDE OF THE
STORM...MAKING THE WINDS THE BIG STORY TNGT-TMRW. LLJ 40-50 KT BHD
DEPARTING LOW. PROJECTED HGT FALLS SUGGEST THAT WE/LL HV MIXING IN
SPITE OF POOR DIURNAL THERMAL PROFILE. SNDGS WL PROVIDE DEEPER
MIXING AS THE JET DEPARTS. THUS...THE DAYTIME HRS SUNDAY WL BE THE
WINDIER TIMEFRAME. GDNC SUPPORTS NNW 20G30-35KT. IF TOP OF THE MIXED
LYR ACHIEVED...THEN CUD HV SOME G40KT MIDDAY SUNDAY. WL ADD TO HWO.

FLOW DIRECTION NOT TOO FVRBL FOR SGNFT UPSLP PCPN. IT CERTAINLY WL
BE COLD ENUF THO FOR ANY PCPN IN THE MTNS TO BE IN THE FORM OF SNW.
CITING STRONG CAA AND CHANNELED PVA...BELIEVE THAT WE/LL HV A PD OF
LGT PCPN TNGT...LINGERING INTO SUN MRNG. AM KEEPING CAT/LKLY POPS
TNGT...FAVORING WRN PENDLETON/HIGHLAND CNTYS. CHC POPS LINGER TO
MIDDAY SUN. ACCUMS WL BE ON THE LWR SIDE...UNDER ADVY CRIT. DAYSHIFT
WL HV THE OPPORTUNITY TO REASSESS SITUATION.

SHUD HV AMPLE CLDCVR TIL THE TROF AXIS CROSSES. THAT MEANS MOCLDY
SKIES TNGT. ANY TEMP DROP WL BE PURELY ADVECTIVE. FOR THAT REASON AM
NOT GOING SUPER COLD...RELATIVELY SPEAKING. MIN-T FCST IN THE 30S WL
BE CHILLY...ENHANCED BY WIND CHILLS. THE ONLY PLACES WHERE SUBFRZG
TEMPS FCSTD ARE SAME LOCATIONS WHERE GROWING SEASON HAS ENDED.

CLDS WL HANG TOUGH IN THE MTNS SUN. HWVR...DUE TO THE AMPLITUDE
OF THE FLOW...THE RDG BLDS IN QUITE QUICKLY...THE SUBSIDENCE OF
WHICH SHUD ERODE CLDS DURING THE AFTN. WE/RE UNDER THE COLD POOL
THO...SO CLDS WONT COMPLETELY DSPT. DUE TO THAT THERMAL STRUCTURE...
AM ON COLD SIDE OF MAXT GDNC.
&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
BY SUNDAY NIGHT...SFC HIGH PRESSURE WILL BE ANCHORED ALONG THE
SOUTHERN APPALACHIANS. THE FORECAST PROBLEM IN THIS TIMEFRAME IS
WHETHER THE HIGH WILL BE CLOSE ENOUGH TO ALLOW DECOUPLING TO OCCUR
AND THUS TEMPS TO BOTTOM OUT. THIS IS MORE LIKELY IN THE SW HALF OF
THE FORECAST AREA...AND LESS LIKELY TOWARD THE MASON-DIXON LINE. THE
FORECAST GRID REFLECTS THIS ACCORDINGLY...AND IN MANY AREAS IS AN
INCREASE IN TEMPERATURE FROM THE PREVIOUS FORECAST. GIVEN THIS
TREND...WILL HOLD OFF ON ISSUING A FREEZE WATCH JUST YET.

RETURN FLOW BEGINS ON MONDAY AS THE UPPER RIDGE AXIS PROGRADES OVER
THE AREA AND THE SFC HIGH SHIFTS TO THE CAROLINA COAST. EXPECT HIGHS
TO REBOUND TO BETWEEN 55 AND 60 IN MOST AREAS. MONDAY NIGHT LOOKS
QUIET. SHELTERED VALLEYS MAY DROP TO THE MID 30S...BUT HIGHER
ELEVATIONS AND URBAN AREAS STAY 40 OR HIGHER.

THE RIDGE AXIS IS SHUNTED SOUTHWARD TUESDAY NIGHT AS THE NEXT UPPER
TROUGH AND ASSOCIATED COLD FRONT APPROACH. THE RETURN MOISTURE FLOW
IS FORECAST TO GET CUT OFF AHEAD OF THE FRONT...AND THE FRONT ITSELF
DOES NOT HAVE PARTICULARLY STRONG UPPER SUPPORT...SO POPS THROUGH
WEDNESDAY WERE CONFINED TO AREAS WEST OF THE I-81 CORRIDOR.

A STRONGER SHORTWAVE AND COLD FRONT MOVE THROUGH WEDNESDAY NIGHT
INTO THURSDAY...AND THIS SHOULD BRING A CHANCE OF SHOWERS. TEMPS
LOOK WARM ENOUGH FOR ALL RAIN. BEHIND THE FRONT THURSDAY NIGHT...
THERE IS POTENTIAL FOR LIGHT UPSLOPE RAIN OR SNOW SHOWERS ALONG/WEST
OF THE DIVIDE. THESE MAY LAST INTO FRIDAY. IT THEN LOOKS COOL AGAIN
FOR NEXT FRIDAY INTO THE FOLLOWING WEEKEND.
&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDS ATTM WL DETERIORATE THRU THE MRNG AS LOPRES STRENGTHENS IN
THE ATLC. THAT PROCESS ALREADY OCCURRING INVOF BWI/MTN...WHICH IS A
LTL FASTER THAN GDNC. HV FCST NO LWR THAN MVFR...DUE MAINLY TO CIGS.
FLGT CATEGORIES WL IMPRV MID-LT AFTN. MRB LKLY THE LAST TO SEE SUCH
PROGRESS. VFR THRU THE NGT.

WINDS LKLY TO BE THE BIGGER FACTOR TAFTN THRU TNGT INTO SUNDAY. NLY
FLOW 15G25KT TO DVLP BY MID AFTN. WL HV A 40-50 KT CORE OF WINDS
2000-3000 FT OFF THE DECK TNGT. WL HV SFC WNDS 20G30-35KT...SO WE
WONT QUITE ACHIEVE LLWS BY DEFINITION. WNDS WL BACK NWLY ON
SUNDAY...W/ 35 KT GUSTS LKLY.

SFC WINDS SHOULD LESSEN SUNDAY NIGHT. GENERALLY VFR WITH NO
SIGNIFICANT HAZARDS THROUGH THE EXTENDED...THOUGH COLD FRONTS WILL
SHIFT WINDS ON TUESDAY NIGHT AND THURSDAY...AND PERHAPS BRING
SCATTERED SHOWERS.
&&

.MARINE...
NLY FLOW ON WATERS INCRSG...AND SITES HV ACHIEVED SCA CRIT BY 2AM.
WINDS WL ONLY INCREASE THRU THE DAY AS LOPRES DVLPS OFF THE CAROLINA
COAST. HV ADDED GLW TO THE BAY S OF SANDY PT INCL MOUTH OF THE PTMC
BASED ON MDL GDNC STRONGLY SUGGESTING G35 KT LKLY. AFTN GUSTS 25-30
KT ELSW. ALL MARINE ZONES FCST TO HV 35-40 KT GUSTS TNGT INTO SUN AS
LOPRES DEEPENS IN THE WRN ATLC AND EJECTS NEWD.

WINDS SHOULD BEGIN TO DECREASE ON THE WATERS SUNDAY EVENING. EXACTLY
HOW FAST REMAINS IN QUESTION...BUT IT IS LIKELY THAT SCA-LEVEL GUSTS
CONTINUE THROUGH SUNDAY NIGHT AND PERHAPS EVEN INTO MONDAY MORNING.

SCA-LEVEL WINDS ARE ALSO POSSIBLE TUESDAY AHEAD OF AN APPROACHING
COLD FRONT...AND AGAIN THURSDAY AND FRIDAY WITH A STRONGER STORM
SYSTEM.
&&

.TIDES/COASTAL FLOODING...
TIDAL DEPARTURES ALL UNDER A FT ABOVE NORMAL...AND SHUDNT INCREASE
MUCH FURTHER. BLOWOUT FLOW DVLPS DURING THE DAYLIGHT HRS...
CONTINUING INTO SUNDAY. BY MIDDAY SUNDAY...DEPARTURES ON THE BAY
SHUD REACH 2 FT -BELOW- NORMAL...ESPECIALLY ANNAPOLIS NORTHWARD. THE
BLOWOUT SHUD BE LESS IN THE POTOMAC.
&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ531-
     539.
     GALE WARNING FROM 8 PM EDT THIS EVENING TO 6 PM EST SUNDAY FOR
     ANZ530-531-535-536-538-539.
     SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ530-
     536-538.
     SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR ANZ542.
     GALE WARNING FROM 3 PM EDT THIS AFTERNOON TO 6 PM EST SUNDAY
     FOR ANZ532>534-537-540>543.
     SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR
     ANZ532>534-537-540-541-543.
     SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 8 PM EDT THIS
     EVENING FOR ANZ535.

&&

$$
SYNOPSIS...HTS
NEAR TERM...HTS
SHORT TERM...HTS
LONG TERM...JE
AVIATION...HTS/JE
MARINE...HTS/JE
TIDES/COASTAL FLOODING...HTS







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