Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KRAH 090611
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
107 AM EST TUE FEB 9 2016

.SYNOPSIS... A SERIES OF DISTURBANCES WILL ROTATE ACROSS THE
CAROLINAS AND MIDDLE ATLANTIC STATES THROUGH TUE...IN CYCLONIC FLOW
ALOFT AROUND AN ANOMALOUSLY STRONG MID-UPPER LEVEL LOW OVER THE
LOWER GREAT LAKES AND OH VALLEY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1025 PM MONDAY...

A LEAD COLD FRONT AND BAND OF SHOWERS THAT PRODUCED PEAK WIND GUSTS
OF 34 KTS AT FAY; 35 KTS AT FBG; AND 37 KTS AT POB...HAS MOVED EAST
OF CENTRAL NC THIS EVENING. WHILE THE ASSOCIATED LEAD SHORTWAVE
TROUGH WILL LIFT NORTHEAST THROUGH EASTERN NC/VA AND MAINTAIN A
CHANCE OF SHOWERS THERE TONIGHT...THOSE ARE EXPECTED TO REMAIN EAST
OF CENTRAL NC. HOWEVER...WV SATELLITE IMAGERY DEPICTS ANOTHER
COMPACT CIRCULATION DIGGING ACROSS THE LOWER OH VALLEY THIS
EVENING...AND THIS FEATURE AND THE ACCOMPANYING SURFACE COLD FRONT
ARE FORECAST TO MOVE INTO THE CENTRAL APPALACHIANS BY 12Z TUE.
FORCING FOR ASCENT DOWNSTREAM OF THE MID-UPPER FEATURE...ACROSS VA
AND NC...IN CONJUNCTION WITH VERY STEEP LAPSE RATES IN EXCESS OF 7.5
C/KM THROUGH A VERY DEEP LAYER (FROM THE SURFACE TO 500 MB) SAMPLED
BY THE 00Z GSO RAOB...WILL RESULT IN SCATTERED SNOW SHOWERS AND
FLURRIES OVERNIGHT...PARTICULARLY ACROSS THE NORTHERN PIEDMONT/IN
CLOSEST PROXIMITY TO THE AFOREMENTIONED COMPACT DISTURBANCE
APPROACHING FROM THE WNW.

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 315 PM MONDAY...

THE DEEP UPPER TROUGH TO OUR WEST WILL MAKE ITS WAY OVERHEAD ON
TUESDAY...WITH A DISTURBANCE WITHIN THE TROUGH FORECAST TO SWING
ACROSS VA AND NORTHERN NC DURING THE AFTERNOON.  STEEP LAPSE RATES
ALOFT...ALONG WITH THE STRONG DCVA AND MOISTENING BETWEEN 5-10K
FEET(COINCIDENT WITH THE ICE NUCLEATION ZONE)...MAY LEAD SOME
ISOLATED SHOWERS NEAR THE NC/VA BORDER....ESPECIALLY LATER IN THE
DAY FROM ROXBORO TO ROANOKE RAPIDS. HOWEVER...MODELS CONTINUE TO
INDICATE MUCH BETTER COVERAGE NORTH OF THE BORDER AND THE ECMWF IS
THE ONLY MODEL TO INDICATE ANY QPF IN THE NORTHERN COASTAL PLAIN.
HIGHS WILL REACH THE UPPER 30S WEST TO MID 40S EAST...BUT DEWPOINTS
IN THE LOWER 20S WOULD PUSH WETBULB PROFILES COLD ENOUGH TO SUPPORT
SNOW SHOWERS OR FLURRIES.  COLD ADVECTION WILL CONTINUE TUESDAY
NIGHT BEHIND THE ARCTIC FRONT...WITH TEMPS FALLING INTO THE LOW/MID
20S.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 400 PM MONDAY...

COLD MID-LATE WEEK...AND EVEN COLDER --PERHAPS RECORD SO-- THIS
WEEKEND...WITH A COUPLE OF OPPORTUNITIES FOR PRECIPITATION (LATE FRI-
FRI NIGHT AND LATE MON-TUE).

A HIGHLY AMPLIFIED PATTERN CHARACTERIZED BY A STRONG WESTERN NOAM
RIDGE AND EASTERN NOAM TROUGH WILL UNDERGO A BRIEF RELAXATION LATE
IN THE WEEK...IN ADVANCE OF A POLAR VORTEX THAT WILL SETTLE ACROSS
SOUTHEAST CANADA AND NEW ENGLAND...AND EFFECTIVELY RE-AMPLIFY THE
FLOW...THIS WEEKEND. A PROGRESSIVE PACIFIC TROUGH WILL THEN FLATTEN
THE WESTERN NOAM RIDGE SUN-MON.

WITHIN THE NW FLOW ALOFT...SHEAR VORTICITY AND ASSOCIATED LOW
AMPLITUDE TROUGHS WILL AMPLIFY INTO THE BASE OF THE TROUGH OVER THE
EASTERN STATES MID-LATE WEEK...WITH EACH SUPPORTING AN AREA OF LIGHT
PRECIPITATION STREAKING SOUTHEASTWARD FROM THE NORTHERN PLAINS TO
THE CENTRAL-SOUTHERN APPALACHIANS. THE MODELS SUGGEST THE LEAD
DISTURBANCE WILL HAVE A MORE LIMITED MOISTURE SUPPLY AND LITTLE LOW
LEVEL SUPPORT FOR THE MAINTENANCE OF PRECIPITATION EAST OF THE
APPALACHIANS ON THU...WHILE THE SECOND WILL BE ACCOMPANIED BY A LOW-
MID LEVEL WAA REGIME AND CONSEQUENTLY HAVE A BETTER CHANCE OF
SUPPORTING A BRIEF PERIOD OF LIGHT PRECIPITATION...MOST LIKELY IN
THE FORM OF SNOW...OR A RAIN/SNOW MIX ACROSS THE SOUTHERN
COUNTIES...CENTERED AROUND FRI EVENING.

A POTENTIALLY MORE SIGNIFICANT SYSTEM WILL ACCOMPANY THE
AFOREMENTIONED PACIFIC TROUGH...AS THE AFOREMENTIONED POLAR VORTEX
SUPPRESSES THE NORTHERN STREAM/PROMOTES CONFLUENT FLOW ALOFT...WHICH
WOULD SUPPORT THE SOUTHEASTWARD MAINTENANCE OF A 1040-1045 MB HIGH
FROM THE ARCTIC. WHILE THIS WOULD YIELD INITIALLY JUST NEAR RECORD
COLD CONDITIONS FOR THE WEEKEND...THE EASTWARD MIGRATION OF THE
PACIFIC TROUGH AND AN INCREASINGLY ACTIVE SOUTHERN STREAM WOULD
RAISE THE PROBABILITY OF STREAM INTERACTION...AND STORMINESS AND
APPALACHIAN COLD AIR DAMMING...MON-TUE.

&&

.AVIATION /06Z FRIDAY THROUGH SATURDAY/...
AS OF 1230 AM TUESDAY...

AREAS OF FOG WITH LIFR TO IFR CIGS/VSBYS AROUND KRDU AND KRWI
THROUGH 09Z SHOULD GET SCOURED OUT BY THE INCREASING MIXED LAYER
ALOFT BEFORE 12Z. SURFACE WINDS SHOULD INCREASE TO 5-10KT BY 12Z.
OTHERWISE... THE WESTERLY WINDS AND DEEP MIXING WILL INCREASE TO 10-
15KT WITH GUSTS TO 20 TO 25KTS ON TUESDAY... WITH POSSIBLY SOME CIGS
AT AROUND 4 TO 5 KFT ALONG WITH MAYBE A FEW SPRINKLES OR FLURRIES.

OUTLOOK...WEDNESDAY AND THURSDAY WILL FEATURE VFR CONDITIONS WITH
GUSTY NORTHWEST WINDS OF 20-25 KTS.  THE NEXT CHANCE OF SUB-VFR
CONDITIONS WILL COME FRIDAY AS A WEAK LOW PRESSURE SYSTEM CROSSES
THE AREA.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.


&&

$$

SYNOPSIS...2
NEAR TERM...2
SHORT TERM...SMITH
LONG TERM...2
AVIATION...BADGETT/SMITH


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.