-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 290821
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
421 AM EDT TUE JUL 29 2014

.SYNOPSIS...
DRIER AND COOLER AIR WILL SETTLE INTO THE REGION IN THE WAKE OF
AN UNUSUALLY STRONG COLD FRONT AS CANADIAN HIGH PRESSURE DROPS
INTO THE REGION. RAIN CHANCES WILL RETURN BY THE UPCOMING WEEKEND
AS HIGH PRESSURE OFFSHORE BUILDS WEST AND BRINGS A RETURN OF
MOISTURE TO THE EAST COAST.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM TUESDAY...STORY FOR THE NEAR TERM WILL BE THE INFLUX
OF LOWER TEMPS/DEWPOINTS AND RESULTANT HUMIDITY LEVELS. A NEARLY
FULL LATITUDE UPPER TROF TO AFFECT THE US...MAINLY EAST OF THE
MISSISSIPPI RIVER DURING THIS NEAR TERM PERIOD. THIS UPPER TROF
AXIS EXTENDS FROM HUDSON BAY OF CANADA SOUTHWARD TO FLORIDA. THIS
UNUSUAL WX PATTERN ALOFT IS REMINISCENT OF WHAT USUALLY OCCURS
DURING THE WINTER SEASON...NOT THE SUMMER SEASON. VARIOUS MODELS
INDICATE 5H TEMPS TO DROP TO AROUND -10...AND 8H TEMPS TO AROUND
+10. VARIOUS MODEL TIME HEIGHT DISPLAYS AND SOUNDINGS INDICATE A
DRY ATM ABOVE 7H...WITH A SHALLOW DEPTH OF MOISTURE IN THE LOW
LEVELS BASICALLY TRAPPED BELOW 7H. WITH THE DAYS HEATING
TODAY...WILL LIKELY OBSERVE SCATTERED TO BROKEN SC/CU/AC WITH
BASES BETWEEN 4K AND 12K FEET. MODELS INDICATE SOME CHANNELED 5H
VORTICITY TO MOVE ACROSS THE FA LATER THIS AFTERNOON AND EVENING
DURING THE TIME WHEN THE UPPER TROF AXIS IS NEARLY OVERHEAD. WILL
CONTINUE WITH LOW AND MID LEVEL CLOUDS INTO TONIGHT. IF ENOUGH
FORCING BECOMES AVBL...WOULD NOT BE SURPRISED TO OBSERVE LOW
CLOUD-TOPPED SHOWERS WITH LITTLE IN THE WAY OF ACCUMULATION.
WILL STAY CLOSER TO THE NAM MODEL MOS GUIDANCE FOR MAX/MIN
TEMPS...ESPECIALLY WHEN DEALING WITH TODAYS MAXES SINCE ITS NEARLY
A CATEGORY LOWER THAN THE GFS MOS GUIDANCE.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...DEEP DRY AIR WILL REMAIN IN PLACE FOR MUCH OF
THE PERIOD AS FLAT MID LEVEL TROUGH JUST WEST OF THE AREA MAINTAINS
WESTERLY FLOW ALOFT. SURFACE HIGH NORTHWEST OF THE AREA WED WILL
SLIDE EAST ACROSS THE SOUTHERN MID ATLANTIC STATES THU. GRADIENT
WILL REMAIN WEAK WITH LIGHT NORTHEAST FLOW BECOMING EASTERLY. HIGHS
CLOSE TO WATER TEMPS WILL PREVENT ANY REAL SEA BREEZE FROM
DEVELOPING DESPITE WEAK WIND FIELD. WEAK DOWNWARD MOTION AND
PRECIPITABLE WATER VALUES AROUND 1 INCH WOULD SUGGEST MOSTLY SUNNY
SKIES WED...THOUGH FILTERED THROUGH INCREASING CIRRUS SHIELD LATER
IN THE DAY. HOWEVER...GUIDANCE CONTINUES TO SHOW SOME WEAK
CONVERGENCE SHOWERS DEVELOPING IN THE AFTERNOON AS EASTERLY WINDS
SETUP. NOT READY TO BUY INTO THESE...ESPECIALLY WITH MOS POP IN THE
SINGLE DIGIT RANGE...SO WILL MAINTAIN A DRY FORECAST. DESPITE PLENTY
OF SUN MID LEVEL TROUGHING KEEPS HIGHS BELOW CLIMO...MID 80S. LOWS
BELOW CLIMO ARE EXPECTED WED NIGHT...MID 60S AWAY FROM THE COAST
WITH MID TO UPPER 60S ALONG THE COAST.

SHORTWAVE DROPPING SOUTHEAST ACROSS THE PLAINS WED INTO THU WILL
CAUSE THE 5H TROUGH TO DIG DURING THU. SOUTHWEST FLOW DEVELOPS AS A
RESULT COMMENCING A SLOW BUT STEADY INCREASE IN DEEP MOISTURE. THIS
WILL LIKELY BE TOO LITTLE TOO LATE AS FAR AS MEASURABLE PRECIP IS
CONCERNED FOR THU...BUT THERE WILL BE POTENTIAL FOR AN ISOLATED
SHOWER ACROSS SC COUNTIES LATE THU NIGHT. CLOUD COVER WILL INCREASE
DURING THE DAY THU WITH SKIES ULTIMATELY BECOMING MOSTLY CLOUD THU
NIGHT. COMBINATION OF CLOUD COVER AND INCREASED DEEP MOISTURE WILL
KEEP LOWS A BIT WARMER. MOST AREAS ARE LIKELY TO REMAIN BELOW CLIMO
BUT ONLY BY A FEW DEGREES.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...DIGGING MID LEVEL TROUGH AND EXPANDING WESTERN
ATLANTIC 5H RIDGE WILL RESULT IN DEEP SOUTHWEST FLOW OVER THE
SOUTHEAST THROUGH THE PERIOD. ABUNDANT DEEP MOISTURE AND PERIODIC
SHORTWAVE ROUNDING THE BASE OF THE TROUGH WILL KEEP THE WEATHER
UNSETTLED THROUGH INTO NEXT WEEK. DIURNAL SHOWERS AND THUNDERSTORMS
ARE EXPECTED EACH DAY BUT THERE WILL ALSO BE THE REMAINS OF A
SURFACE BOUNDARY STALLED OFF THE SOUTHEAST COAST WHICH WILL MOVE
ONSHORE AT SOME POINT OVER THE WEEKEND. MEDIUM RANGE GUIDANCE
CONTINUES TO SUGGEST POSSIBILITY OF WEAK SUB TROPICAL DEVELOPMENT
ALONG THIS BOUNDARY AT SOME POINT...BUT WITH EACH SUBSEQUENT MODEL
RUN THE FEATURE BECOMES WEAKER/MORE DIFFUSE. NOT READY TO COUNT ON IT
YET BUT DO THINK THE PRESENCE OF THE FRONT WILL INCREASE COVERAGE
SAT/SUN. WILL BUMP WEEKEND POP TO HIGH CHC WHILE MAINTAINING LOW/MID
CHC POP FRI/MON. CLOUD COVER AND [PRECIP ALONG WITH MID LEVEL
TROUGHING WILL KEEP HIGHS BELOW CLIMO THROUGH THE PERIOD. LOWS WILL
RUN NEAR TO ABOVE CLIMO AIDED BY CLOUD COVER.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
AS OF 06Z...FRONT HAS DROPPED ACROSS MUCH OF THE REGION WITH THE
STRONG CONVECTION NOW WELL OFFSHORE. EXPECT CONVECTIVE DEBRIS
CLOUDS TO DISSIPATE AS THEY MOVE OFF THE COAST EARLY ON. LOOKING
AT FAIR WEATHER SC/CU DURING THE DAY TUE...AS COOLER AND DRIER
AIR CONTINUE TO PUMP ACROSS THE REGION UNDER NW-NE FLOW. THE
COASTAL TERMS MAY VEER TO THE E BRIEFLY THIS AFTN. SPEEDS AT 5 TO
15 KT...DROPPING TO LESS THAN 5 KT AFTER SUNSET TUE. OVERALL...
LOOKING AT VFR CONDITIONS THRUOUT THE 06Z ISSUANCE PERIOD.

EXTENDED OUTLOOK...MVFR DUE TO MORNING FOG POSSIBLE THURSDAY AND
FRIDAY. OTHERWISE EXPECT VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 330 AM TUESDAY...COLD FRONT IS SLOWLY SNAKING ESE ACROSS THE
LOCAL WATERS...AND SHOULD BE ENTIRELY OFFSHORE AROUND DAYBREAK
TUE. SFC PG BEHIND THE COLD FRONT HAS RELAXED CONSIDERABLY PRIOR
TO ITS PASSAGE. THE POST COLD FRONTAL SURGE ASSOCIATED WITH THE
COOLER AIR AND INFLUX OF DRIER AIR IE. LOWER DEWPOINTS...WILL
PRODUCE AN ACTIVE NNW-NE WIND AT 10-15 KTS TODAY INTO
TONIGHT. IF THE SFC PG ENDS UP BEING TIGHTER THAN PREVIOUSLY
THOUGHT...THEN HIER WIND SPEEDS WILL NEED TO BE APPLIED.
SIGNIFICANT SEAS HAVING SUBSIDED FROM THEIR RECENT HIGHS
YESTERDAY...WILL HOLD IN A 2 TO 4 FOOT RANGE. THE 4 FOOTERS ARE
RESERVED FOR THE OUTER WATERS OFF CAPE FEAR. DOMINANT PERIODS WILL
RANGE BETWEEN 6 TO 7 SECONDS.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...HIGH PRESSURE NORTHWEST OF THE WATERS WILL
DRIFT EAST WED INTO THU. GRADIENT WILL REMAIN LIGHT THROUGH THE
PERIOD WITH EASTERLY WINDS GENERALLY 10 KT OR LESS. LACK OF
SIGNIFICANT TEMP DIFFERENCE BETWEEN LAND/WATER RULES OUT A SEA
BREEZE EITHER DAY BUT A LAND BREEZE WILL BE POSSIBLE...ESPECIALLY
WED NIGHT WITH LOWS DIPPING INTO THE MID TO UPPER 60S. SEAS WILL
RUN 2 TO 3 FT THROUGH THE PERIOD.

LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...STALLED FRONT OFFSHORE ON FRI WILL BE PUSHED
WEST FRI NIGHT INTO SAT...ACCOMPANIED BY UNSETTLED WEATHER. GRADIENT
OVER THE WATERS WILL REMAIN WEAK THROUGH THE PERIOD GIVEN THE
PROXIMITY TO THE FRONT...BUT DIRECTION WILL BE DEPENDENT ON LOCATION
OF THE BOUNDARY. WINDS WILL GENERALLY HAVE AN EASTERLY COMPONENT BUT
COULD RANGE FROM SOUTHEAST TO NORTHEAST AT ANY GIVEN MOMENT INTO SAT
BEFORE BECOMING SOUTHEAST AS THE BOUNDARY MOVES ONSHORE. LIGHT WINDS
AND CHANGEABLE DIRECTION WILL KEEP SEAS IN THE 2 TO 3 FT RANGE.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...III
NEAR TERM...DCH
SHORT TERM...III
LONG TERM...III
AVIATION...DCH