AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
130 PM PDT FRI JUL 4 2008
.SYNOPSIS...
A SHALLOW MARINE LAYER WILL CONTINUE COASTAL LOW CLOUDS AND FOG
DURING THE NIGHTS AND MORNINGS. OTHERWISE...UPPER LEVEL HIGH
PRESSURE WILL KEEP THE WEATHER FAIR WITH WARM TO HOT DAYS INLAND.
A SMALL AMOUNT OF MID LEVEL MOISTURE WILL BRING SOME CLOUDS TO THE
MOUNTAINS THIS AFTERNOON WITH A SLIGHT CHANCE OF THUNDERSTORMS OVER
THE SAN DIEGO COUNTY MOUNTAINS.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
EARTH REACHED APHELION OR FARTHEST POINT FROM THE SUN IN ITS ORBIT
AROUND THE SUN...DISTANCE 94.5 MILLION MILES...AROUND 08Z TODAY.
MARINE LAYER REMAINS VERY SHALLOW THIS AFTERNOON WITH MDCRS
SOUNDINGS FROM KSAN AND KSNA INDICATING A DEPTH OF LESS THAN 300
FEET. STRATUS/FOG REMAINS CONFINED TO THE IMMEDIATE COAST.
MID AND HIGH LEVEL MOISTURE CONTINUE TO MOVE OVER THE MOUNTAINS AND
DESERTS FROM THE EAST AND SOUTHEAST BUT NO VERTICAL DEVELOPMENT AT
THIS TIME EXCEPT OVER THE MOUNTAINS OF NORTHERN BAJA SOUTH OF THE
BORDER.
LOW LEVEL MOISTURE FROM A GULF SURGE REMAINS OVER THE SOUTHERN
DESERTS WITH DEW POINTS NEAR 70 F OR GREATER.
12Z MODELS CONTINUE TO SHOW THE AREA UNDER A WEAK FLOW ASSOCIATED
WITH A CULL BETWEEN THE RIDGE OFFSHORE AND THE ONE TO THE EAST. THIS
CONTINUES THROUGH THE WEEKEND WHICH SHOULD LIMIT ANY CONVECTION OVER
THE MOUNTAINS. SHOULD THE SOUTHERLY FLOW PUSH WESTWARD OVER THE
MOUNTAINS...CONVECTION WOULD BE MORE WIDESPREAD. MODELS CONTINUE TO
SHOW A FAIRLY SIGNIFICANT AMOUNT OF MID LEVEL MOISTURE OVER THE AREA
TODAY THROUGH SATURDAY THEN FADING AWAY ON SUNDAY.
IN THE LONGER RANGE...ECMWF MODEL IS MORE BULLISH ON MOISTURE LATE
IN THE COMING WEEK INTO NEXT WEEKEND OVER THE AREA THAN THE GFS
MODEL. THE GFS MODEL DOES SHOW SOME MOISTURE BUT NOT AS DEEP. AT
THIS TIME WILL LEAN TOWARDS JUST PARTLY CLOUDY FOR THE MOUNTAINS FOR
THAT PERIOD. OTHERWISE CONTINUED DRY THROUGH THE PERIOD.
&&
.AVIATION...
042000Z...SHALLOW MARINE LAYER BELOW 1000 FT. LOW STRATUS AND FOG
PERSISTED EARLY THIS AFTERNOON NEAR THE IMMEDIATE COAST AND BEACHES
BUT SHOULD GENERALLY CLEAR OUT THRU 23Z. BASES WERE MAINLY BELOW 500
FT MSL WITH 3-5SM MVFR VISIBILITY IN FOG/HAZE...EXCEPT SOME BEACH
SITES AT 20Z REPORTED LOCAL 1SM OR LESS.
FOR TONIGHT AREAS OF STRATUS AND PATCHY FOG WILL START TO REFORM
MAINLY AFTER 06Z NEAR THE IMMEDIATE COAST AND BRIEFLY REACH 5-10
MILES INLAND FROM 12-15Z SAT. OTHERWISE LOW CLOUDS AND FOG WILL
STAY CONFINED ALONG THE IMMEDIATE COASTLINE AFTER 15Z SAT.
ABOVE THE MARINE LAYER...UNRESTRICTED VISIBILITIES WILL CONTINUE
THIS AFTERNOON THROUGH TONIGHT. SOME AFTERNOON CUMULUS OVER THE
MOUNTAINS AND OCCASIONALLY SOME BANDS OF ALTOCU WITH BASES AROUND
FL100.
MAX TEMPERATURES SATURDAY FOR KPSP/KTRM FROM 41-44C...KSNA 25-28C.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...HORTON
AVIATION/MARINE...LAVIS
NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
430 AM PDT THU JUL 3 2008
UPDATED AVIATION
.SHORT TERM (TODAY-SAT)...
LATEST ACARS SOUNDING NEAR KLAX INDICATED MARINE LAYER NEAR 1100 FT
DP THIS MORNING. HOWEVER...LAX-DGT SFC GRADS WERE TRENDING SLIGHTLY
OFFSHORE FROM 24-HOURS AGO. THEREFORE...EXPECTING STRATUS TO STAY
LIMITED TO SOUTHERN LA COUNTY COASTAL AREAS AND POSSIBLY NUDGING
INTO THE EASTERN SAN GABRIEL VALLEY JUST BEFORE DAWN. TEMPS SHOULD
BE A DEGREE OR TWO WARMER TODAY IN MOST LOCATIONS AS 950 MB TEMPS
AND THICKNESS LVLS INCREASE JUST SLIGHTLY. THE 592 DM UPPER LVL HIGH
WHICH IS CURRENTLY CENTERED OVER SE CAL AND AZ WILL BEGIN TO PHASE
SLIGHTLY TO THE NE NEAR THE FOUR CORNERS REGION TODAY.
GENERALLY...THIS PATTERN CAN BE CONDUCIVE TO DRAW UP SOME MONSOONAL
MOISTURE AROUND THE HIGH FROM AZ AND MEXICO INTO SOUTHEASTERN CAL.
BUT THIS WONT LAST BUT ONLY TWO DAYS AND WATER VAPOR IMAGERY SHOWS
NO MID LEVEL MOISTURE TO DRAW FROM. MEANWHILE A BROAD UPPER LVL TROF
WILL CONTINUE TO STAY PUT ACROSS THE EASTERN PAC INTO NO CAL THROUGH
FRIDAY AS UPPER RIDGE TO THE EAST KEEPS IT STATIONARY.
THEREFORE...FRIDAY SHOULD BE A REPEAT OF TODAYS TEMPS AND LOW CLOUD
REGIME NEAR THE COASTAL AREAS.
ON SAT...UPPER HIGH BEGINS TO BREAKDOWN AS UPPER TROF MOVES
EASTWARD. EXPECT SLIGHTLY COOLER CONDITIONS...ESPECIALLY ACROSS THE
COASTAL AREAS AS LOW CLOUDS SHOULD BE A BIT MORE WIDESPREAD. VALLEYS
AND INTERIOR AREAS WILL CONTINUE TO TO BE IN THE 90S TO NEAR 100 IN
SOME LOCATIONS.
.LONG TERM (SUN-WED)...
BOTH GFS AND ECMWF ARE IN PRETTY GOOD AGREEMENT THAT A STRONG UPPER
LVL HIGH WILL BEGIN TO BUILD IN FROM THE NORTHWEST ON SUNDAY. THE
HIGH STRENGTHENS TO 593DM BY MON COVERING A WIDE AREA OF THE
WESTERN US BY TUE AND HOLDS STRONG THRU WED. EXPECT SOME WARMING ON
SUNDAY WITH MANY INTERIOR LOCATIONS EASILY REACHING TRIPLE DIGITS.
WHILE THE COASTAL AREAS SHOULD SEE LESS IN STRATUS COVERAGE...TEMPS
WILL ALSO WARM A BIT. IT COULD BE DOWNRIGHT HOT BY TUE AND WED WITH
SOME INTERIOR LOCATIONS REACHING NEAR 110 IN THE WARMEST LOCATIONS.
CURRENT FORECAST PACKAGE DOES TREND TEMPS HIGHER BUT NOT QUITE THIS
HOT. SHOULD HAVE A BETTER ON NEXT WEEK`S HEAT BY THIS WEEKEND.
&&
.AVIATION...WILL BE UPDATED AFTER 12Z TAF PACKAGE.
KLAX...THERE IS A GOOD CHANCE (60-80 PERCENT) THAT IFR CIGS WILL
AFFECT THE AIRPORT BY 13Z. CIGS SHOULD CLEAR AROUND 16Z OR 17Z.
VSBYS SHOULD REMAIN VFR. TYPICAL AFTERNOON SEABREEZES OF 10 TO 14 KT
ARE EXPECTED.
KBUR...VFR CONDITIONS EXPECTED TO PERSIST THROUGHOUT THE PERIOD.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
GALE WARNING (SEE LAXCWFLOX).
SMALL CRAFT ADVISORY (SEE LAXCWFLOX).
&&
$$
PUBLIC...KAPLAN
AVIATION...BRUNO
WWW.WEATHER.GOV/LOSANGELES
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
401 AM PDT THU JUL 3 2008
.SHORT TERM (TODAY-SAT)...
LATEST ACARS SOUNDING NEAR KLAX INDICATED MARINE LAYER NEAR 1100 FT
DP THIS MORNING. HOWEVER...LAX-DGT SFC GRADS WERE TRENDING SLIGHTLY
OFFSHORE FROM 24-HOURS AGO. THEREFORE...EXPECTING STRATUS TO STAY
LIMITED TO SOUTHERN LA COUNTY COASTAL AREAS AND POSSIBLY NUDGING
INTO THE EASTERN SAN GABRIEL VALLEY JUST BEFORE DAWN. TEMPS SHOULD
BE A DEGREE OR TWO WARMER TODAY IN MOST LOCATIONS AS 950 MB TEMPS
AND THICKNESS LVLS INCREASE JUST SLIGHTLY. THE 592 DM UPPER LVL HIGH
WHICH IS CURRENTLY CENTERED OVER SE CAL AND AZ WILL BEGIN TO PHASE
SLIGHTLY TO THE NE NEAR THE FOUR CORNERS REGION TODAY.
GENERALLY...THIS PATTERN CAN BE CONDUCIVE TO DRAW UP SOME MONSOONAL
MOISTURE AROUND THE HIGH FROM AZ AND MEXICO INTO SOUTHEASTERN CAL.
BUT THIS WONT LAST BUT ONLY TWO DAYS AND WATER VAPOR IMAGERY SHOWS
NO MID LEVEL MOISTURE TO DRAW FROM. MEANWHILE A BROAD UPPER LVL TROF
WILL CONTINUE TO STAY PUT ACROSS THE EASTERN PAC INTO NO CAL THROUGH
FRIDAY AS UPPER RIDGE TO THE EAST KEEPS IT STATIONARY.
THEREFORE...FRIDAY SHOULD BE A REPEAT OF TODAYS TEMPS AND LOW CLOUD
REGIME NEAR THE COASTAL AREAS.
ON SAT...UPPER HIGH BEGINS TO BREAKDOWN AS UPPER TROF MOVES
EASTWARD. EXPECT SLIGHTLY COOLER CONDITIONS...ESPECIALLY ACROSS THE
COASTAL AREAS AS LOW CLOUDS SHOULD BE A BIT MORE WIDESPREAD. VALLEYS
AND INTERIOR AREAS WILL CONTINUE TO TO BE IN THE 90S TO NEAR 100 IN
SOME LOCATIONS.
.LONG TERM (SUN-WED)...
BOTH GFS AND ECMWF ARE IN PRETTY GOOD AGREEMENT THAT A STRONG UPPER
LVL HIGH WILL BEGIN TO BUILD IN FROM THE NORTHWEST ON SUNDAY. THE
HIGH STRENGTHENS TO 593DM BY MON COVERING A WIDE AREA OF THE
WESTERN US BY TUE AND HOLDS STRONG THRU WED. EXPECT SOME WARMING ON
SUNDAY WITH MANY INTERIOR LOCATIONS EASILY REACHING TRIPLE DIGITS.
WHILE THE COASTAL AREAS SHOULD SEE LESS IN STRATUS COVERAGE...TEMPS
WILL ALSO WARM A BIT. IT COULD BE DOWNRIGHT HOT BY TUE AND WED WITH
SOME INTERIOR LOCATIONS REACHING NEAR 110 IN THE WARMEST LOCATIONS.
CURRENT FORECAST PACKAGE DOES TREND TEMPS HIGHER BUT NOT QUITE THIS
HOT. SHOULD HAVE A BETTER ON NEXT WEEK`S HEAT BY THIS WEEKEND.
&&
.AVIATION...WILL BE UPDATED AFTER 12Z TAF PACKAGE.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
GALE WARNING (SEE LAXCWFLOX).
SMALL CRAFT ADVISORY (SEE LAXCWFLOX).
&&
$$
PUBLIC...KAPLAN
AVIATION...BRUNO
WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS MIAMI FL
210 PM EDT FRI JUL 4 2008
.AVIATION...
FOR IMMEDIATE CONCERNS...TERMINAL KPBI WILL CONTINUE TO HAVE
PERIODS OF IFR CONDITIONS THROUGH THE NEXT HOUR...AND IMPROVING
THEREAFTER BUT WITH VCTS FOR THE REMAINDER OF THE AFTERNOON AND
EARLY EVENING. ALTHOUGH THE REMAINING TERMINALS ARE NOT AFFECTED
BY THUNDERSTORMS AT THE MOMENT...AS THE AFTERNOON PROGRESSES THE
EFFECTS OF THE OUTFLOW BOUNDARIES FROM PREVIOUS THUNDERSTORMS AND
THE SEA BREEZES COMBINED WITH GOOD POTENTIAL FOR CONVECTION THIS
AFTERNOON WILL RESULT IN VCTS FOR THESE TERMINALS THE REMAINDER
OF THE AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 1035 AM EDT FRI JUL 4 2008/
UPDATE...12Z MIA SOUNDING TODAY SHOWS SLIGHTLY MORE STABLE
CONDITIONS THAN 24 HRS AGO (THURSDAY) WITH WARMER 500 MB TEMPS AND
LOWER CAPE (AFTER A MODIFIED SOUNDING FOR AFTERNOON CONDITIONS) BUT
STILL UNSTABLE ENOUGH TO RESULT IN SHWRS/TSTMS DEVELOPING OVER THE
AREA DURING AFTERNOON HOURS. IN FACT K INDEX IS HIGHER, WHICH COULD
INDICATE SCT TO NMRS DEVELOPMENT. HOWEVER, THE POTENTIAL FOR STRONG
MICROBURSTS IS SLIGHTLY LOWER THAN YESTERDAY`S AS THERE IS NO REAL
(ACTUALLY SMALLER AREA) ELEVATED SOURCE OF DRY AIR. LOCAL
CALCULATIONS SUGGEST MAX DOWNDRAFT POTENTIAL OF 30 TO 40 MPH, BUT
WILL STRETCH IT A LITTLE BIT AND KEEP THE MENTIONING OF GUSTS UP TO
50 TO 55 MPH IN THE HWO WITH THE STRONGEST STORMS THAT DEVELOP THIS
AFTERNOON. PW VALUE IS HIGHER TODAY (1.82 INCHES) AND EXPECTED STORM
MOTION SLIGHTLY SLOWER, SO WL EXPECT LOCALLY HEAVY DOWNPOURS WITH
ANY STORM. SINCE THE LOW LVL FLOW IS MAINLY ESE, THIS WILL TEND TO
KEEP INITIAL CONVECTIVE ACTIVITY AWAY FROM THE ERN METRO AREAS IN
BROWARD/MIAMI-DADE, BUT THE MEAN STEERING FLOW WILL STILL PUSH THE
STORMS SLOWLY NORTHEAST, ONCE THEY DEVELOP. WEST COAST SEA BREEZE
MAY DEVELOP AGAIN AND KEEP STORMS EAST OF NAPLES METRO AREA, THUS
LOWER POPS ARE INDICATED FOR NAPLES. CURRENT FORECAST PACKAGE CALLS
FOR SCT TO LIKELY POPS, ESPECIALLY ACROSS THE INTERIOR, AND THE
CURRENT HWO CALLS FOR A FEW STRONG STORMS, THEREFORE, CHANGES ARE
NOT NEEDED AT THIS TIME.
RGH
AVIATION...
THE CONTINUING PRESENCE OF THE UPPER LEVEL TROUGH IN THE GULF WILL
HELP TO ENHANCE CONVECTION THIS AFTERNOON. WEAK LOW LEVEL EASTERLY FLOW
WILL ALLOW SHOWERS/TSTORMS TO FORM INLAND ALONG THE EAST COAST IN THE EARLY
AFTERNOON...WITH WESTERLY STEERING FLOW BRINGING THE CONVECTION IN
THE VICINITY OF OR ACROSS THE EAST COAST TERMINALS LATER IN THE
AFTERNOON AND EARLY EVENING. TERMINAL KAPF SHOULD ALSO BE IMPACTED
BY THUNDERSTORM ACTIVITY THIS AFTERNOON. ALL TERMINALS MAY
EXPERIENCE PERIODS OF MVFR CONDITIONS...WITH IFR CONDITIONS
POSSIBLE IN BRIEF PERIODS.
PREV DISCUSSION... /ISSUED 451 AM EDT FRI JUL 4 2008/
DISCUSSION...THIS INDEPENDENCE DAY IS EXPECTED TO FEATURE VERY
SIMILAR WEATHER CONDITIONS AS WERE EXPERIENCED YESTERDAY. SURFACE
RIDGE OF HIGH PRESSURE OVER SOUTH CENTRAL FL WILL ALLOW FOR A
PREVAILING E-SE LOW LEVEL WIND FLOW...BUT SLIGHTLY VEERED CLOSER
TO THE RIDGE AXIS ACROSS THE LAKE REGION TO PALM BEACH COUNTY.
FLOW WILL BE LIGHT ENOUGH TO ALLOW FOR SEA BREEZES TO PUSH INLAND
AT BOTH COASTS. THE RESULT IS AN EXPECTATION OF CONVECTION
FOCUSING ACROSS INLAND AREAS THIS AFTERNOON. FOLLOWED VERY CLOSELY
TO THE WRF-NMM MODEL WHICH HAS HAD AN EXCELLENT HANDLE ON
GENERAL PLACEMENT OF CONVECTION LATELY. THIS MODEL SHOWS THE EAST
COAST SEA BREEZE BECOMING WELL ESTABLISHED LATE IN THE
DAY...LEAVING CONDITIONS DRY ACROSS THE EAST COAST METRO AREAS
FROM LATE AFTERNOON THROUGH THE NIGHT...BODING WELL FOR FIREWORK
DISPLAYS. CONVECTION WILL WANE THIS EVENING OVER THE WESTERN HALF
OF THE AREA...AND MUCH OF IT SHOULD BE DISSIPATED IN TIME FOR
FIREWORKS.
AN INCOMING SHORTWAVE TROUGH OVER THE NE GULF WILL MOVE ACROSS
THE AREA DURING PEAK HEATING. THESE CAN BE TROUBLE MAKERS IN FLA
IN THE SUMMERTIME. NO ACARS SOUNDINGS ARE CURRENTLY AVAILABLE
ACROSS FL EARLY THIS MORNING...BUT FCST SOUNDINGS FROM BOTH THE
GFS AND NAM SHOW WARMING MID LEVELS WITH WEAKER LAPSE RATES...AS
WELL AS AN ABSENT OF A GOOD DRY LAYER. THEREFORE...WILL DEPICT
ONLY STRONG STORMS IN THE HAZARDOUS WEATHER OUTLOOK ATTM. DAY
SHIFT CAN BETTER ASSESS IF THERE IS ANY SEVERE POTENTIAL WITH THE
12Z SOUNDINGS. AGAIN...FOCUS FOR STORMS IS EXPECTED TO BE INLAND
AWAY FROM BOTH COASTS.
THE RIDGE WILL MOVE INTO NORTH FLORIDA BY SUNDAY...THEN REMAIN
THERE THROUGH EARLY NEXT WEEK...POSSIBLY MOVING BACK SOUTH MID
WEEK...BUT STILL IT LOOKS TO RESIDE NORTH OF THE LOCAL AREA
THROUGH THE PERIOD. THIS WILL MAINTAIN A PREVAILING E-SE WIND
FLOW WITH FOCUS OF CONVECTION BEING ACROSS INTERIOR/GULF COASTAL
LOCALES. ONLY SIGNIFICANT CHANGES TO LATER PERIODS IN THE FCST WAS
TO INCREASE POPS FOR LATE SATURDAY NIGHT THROUGH SUNDAY NIGHT.
GFS...NAM...AND THE ECMWF ALL SHOW A LOW LEVEL TROUGH MOVING
ACROSS THE AREA ON SUNDAY FROM THE SOUTHEAST...WITH INCREASING
CONVERGENCE/MOISTURE...PWATS CLIMBING ABOVE 2 INCHES. GFS/NAM
SHOW LIKELY POPS...AND CANNOT ARGUE WITH THIS...SO INCREASED POPS
TO LIKELY ALL AREAS FOR SUNDAY. ALTHOUGH FLOW WILL BE
E-SE...EXPECT SHRA/TSRA TO MOVE ONSHORE THE EAST COAST...SO
ANYWHERE IS PRONE TO NUMEROUS SHRA/TSRA ON SUNDAY. REST OF PERIOD
SHOULD FEATURE A TYPICAL SUMMERTIME PATTERN OF MAINLY AFTERNOON
CONVECTION...WITH FOCUS INTERIOR/GULF COAST.
MARINE...WINDS LESS THAN 15 KT AND SEAS 4 FT OR LESS WILL PREVAIL
THROUGH THE PERIOD. PREVAILING WINDS WILL BE FROM THE E-SE.
FIRE WEATHER...NO CONCERNS DUE TO HIGH MOISTURE LEVELS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 74 89 76 88 / 20 50 40 60
FORT LAUDERDALE 78 87 77 86 / 20 50 50 60
MIAMI 78 88 76 88 / 20 50 50 60
NAPLES 73 90 73 90 / 30 60 40 60
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
LONG TERM...04/AT
SHORT TERM/AVIATION...04/AT
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
640 AM CDT THU JUL 3 2008
.DISCUSSION...
355 AM CDT
COLD FRONT HAS JUST ABOUT CLEARED THE SE CORNER OF THE FA AT 08Z
WITH ALL METARS NOW REPORTING N-NE WINDS. LINGERING SHRA EXTREME
SE FA SHOULD BE ENDING WITHIN THE NEXT HR OR TWO AS DRYING OF LOW
LEVELS PUSHES DEEPER INTO CENTRAL IL AND SUBSIDENCE IN WAKE OF
SHORT WAVE TROF MOVING E INTO THE CENTRAL GREAT LAKES OVERSPREADS
THE REGION.
COMPACT MID LEVEL LOW OVER KTAZ IN S CENTRAL IL EVIDENT IN
COMPOSITE RADAR LOOP WILL CONTINUE EASTWARD THIS MORNING ENDING
THE RA IN W CENTRAL IND. ANOTHER SHORT WAVE CURRENTLY MOVING SE
OVER SW IA AND NW MO GENERATING TS ALONG I70 ACROSS MO. FURTHER N
INTO S CENTRAL IA NO RA REPORTED FROM THE RADAR ECHOES THERE. ONLY
MID LEVEL CLOUDS AS FRONT HAS ALREADY PASSED THRU SOUTHERN IA AND
FAR NW MO WITH LOW LEVEL DRYING BECOMING DEEPER.
SOUTHWARD PROGRESS OF THE COLD FRONT TO CONTINUE TODAY BUT MUCH
SLOWER AS IT IS STARTING TO BECOME PARALLEL WITH THE MID LEVEL
FLOW ACROSS CENTRAL IL AND IND. AS THE MO/IA SHORT WAVE MOVES
ACROSS CENTRAL IL AND IND TODAY IT MAY SPREAD SHRA AND TS BACK
ACROSS THOSE AREAS SO WILL MAINTAIN SLIGHT CHANCE POPS ACROSS
NEIGHBORING FAR S PORTION OF THE FA THRU 18Z.
MODELS ALL INDICATE MULTIPLE SHORT WAVES DROPPING ACROSS THE
REGION BUT BY LATE TODAY ANY THREAT OF RA WILL BE GRADUALLY
SINKING S FROM CENTRAL IL AND IND AS THE SURFACE RIDGE NOW CENTERED
OVER ND CONTINUES TO BUILD ACROSS THE UPPER MIDWEST AND FEEDS DRY
COOL AIR ACROSS THE FA. VERY COOL AIR FOR EARLY JULY AND LONG FETCH
DOWN 55-60F MID LAKE WATERS WILL KEEP LAKESIDE LOCATIONS IN THE
60S THRU THE DAY WHILE INLAND TEMPS ONLY TOP OUT IN THE LOWER AND
MID 70S...SOME 10-12 DEG BELOW NORMAL.
SURFACE RIDGE TO BE PARKED OVER THE GREAT LAKES FOR INDEPENDENCE
DAY KEEPING COOL AIR OVER REGION. UPPER TROF AXIS PROGGED TO
REMAIN ACROSS LOWER MI SOUTHWESTWARD ACROSS THE MID MS VALLEY TO
AR. GFS MODELS PERSISTS IN BRINGING A SIGNIFICANT MID LEVEL LOW
AND ACCOMPANYING LOW LEVEL CIRCULATION ACROSS SOUTHERN IL AND IND
FRI AND SPREADS RA BACK TO THE EXTREME SE PART OF THE FA. FEEL IT
IS OVERDOING THINGS AND THAT DEEP DRY LOW LEVEL AIRMASS IN PLACE
WILL PRECLUDE ANY RA THAT FAR N.
4TH TO STILL BE COOL/COMFORTABLE DEPENDING ON POINT OF VIEW BUT
WITH SYNOPTIC FLOW OUT OF THE ENE-E THE FETCH FOR LAKE COOLING
WILL BE GREATLY REDUCED SO ALL LOCATIONS EXCEPT RIGHT AT LAKESIDE
WILL BE IN THE 70S. TEMPS TO CLIMB BACK TO NORMALS BUY SUN AS
UPPER RIDGE BUILDS ACROSS THE UPPER MS VALLEY INTO THE UPPER
MIDWEST AND WARM AIR OVER THE PLAINS STARTS TO SPREAD ACROSS THE
REGION ON STRENGTHENING RETURN FLOW.
INCREASING LOW LEVEL MOISTURE WITH THIS RETURN FLOW AND ANOTHER
SHORT WAVE AND ACCOMPANYING COLD FRONT TO BE PUSHING INTO THE
UPPER MIDWEST SUN NIGHT. ANY TS THAT DEVELOP UPSTREAM MAY PERSIST
INTO INTO OVERNIGHT SUN NIGHT/MON MORNING AND REACH NW PORTION OF
FA BY DAYBREAK. UPPER TROF TO DROP FURTHER SE ACROSS THE UPPER
MIDWEST DURING THE DAY MON WITH THE COLD FRONT APPROACHING FROM
THE NW KEEPS CHANCES OF TS THRU MON NIGHT AS FRONT EVENTUALLY
MOVES INTO NORTHERN IL.
TRS
&&
.AVIATION...
12 UTC TAF...
THE SKY WILL HAVE SCATTERED CLOUDS THIS AFTERNOON. SATELLITE
IMAGERY WAS USED TO ESTIMATE THE MOVEMENT OF CLOUDS. THE WATER
VAPOR IMAGERY SHOWS THE UPPER LEVEL JET MOVING SOUTH INTO NORTHERN
ILLINOIS THIS MORNING. THE WOLCOTT INDIANA PROFILER SHOW A
PREDOMINATELY WEST WIND UP TO 8 KILOMETERS. THE WIND BECOMES 20
KNOTS ABOVE ONE KILOMETER. NORTH OF THE WOLCOTT THE ACARS SOUNDING
AT RFD SHOWS THE EFFECT OF THE DIFFERENT AIR MASS NORTH OF THE
FRONT. THE WIND IS FROM THE NORTHEAST UP TO 2 KILOMETERS AND HAS A
SPEED OF 20 TO 23 KNOTS. THE MIXING HAS BEGUN IN THE LOWER
ATMOSPHERE AS THE BOUNDARY LAYER BECOMES MORE MIXED DUE TO SOLAR
HEATING. WILL FORECAST WIND GUSTS OF UP TO 20 KNOTS THROUGH 20 UTC.
AFTER 20 UTC...THE FRONT WILL BE FARTHER SOUTH AND THE GRADIENT AND
HORIZONTAL DIFFERENCE IN THE WIND WILL NOT BE AS GREAT.
&&
.MARINE...
210 AM CDT
A LARGE HIGH WILL MOVE OVER LAKE MICHIGAN BY THIS EVENING. THE NORTH
WIND OF 15 TO 25 KNOTS WILL DIMINISH BY THIS EVENING. THE HIGH WILL
MOVE EAST INTO NEW YORK ND THE APPALACHIAN MOUNTAINS BY SUNDAY. A
LOW WILL MOVE INTO ONTARIO AND MANITOBA. ANOTHER LOW WILL DEVELOP
OVER KANSAS. THESE LOW WILL CAUSE THE WIND TO BECOME MORE SOUTHERLY
OVER LAKE MICHIGAN SUNDAY.
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 11 PM CDT THIS EVENING FOR LMZ740-
LMZ741-LMZ742-LMZ743-LMZ744-LMZ745.
&&
$$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
310 AM EDT THU JUL 3 2008
.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE THROUGH TONIGHT. A WEAK COLD FRONT WILL
STALL ACROSS THE AREA THROUGH THE HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WATER VAPOR LOOP SHOWS A SHORT WAVE LIFTING INTO THE CANADIAN
MARITIMES...AS THE NEXT TROUGH SLIDES TO THE SOUTHEAST OVER THE
GREAT LAKES. WEAK RIDGING WAS IN PLACE OVER THE GULF STATES. A RIDGE
OVER THE SOUTHWEST CONUS IS AMPLIFYING NORTHWARD ALONG THE ROCKIES.
ACARS 400-250MB WIND OBSERVATIONS REVEAL A SOUTHERLY 80-110KT JET
FROM THE MID ATLANTIC COAST NORTHWARD OVER NEW ENGLAND. A WESTERLY
80-110KT JET EXTENDED EAST ACROSS THE UPPER GREAT LAKES...PHASING
WITH THE AFOREMENTIONED JET OVER THE CANADIAN MARITIMES. 02Z SURFACE
ANALYSIS PLACED A 1018MB ANTICYCLONE ACROSS THE INTERIOR
CAROLINAS...WITH A TROUGH ALONG THE LEE OF THE CENTRAL APPALACHIANS.
A WARM FRONT EXTENDING FROM THE EASTERN GREAT LAKES SOUTH TO THE
SOUTHERN GULF STATES WAS BEGINNING TO LIFT NORTHEAST. THE COLD FRONT
STRETCHED FROM THE CENTRAL GREAT LAKES SOUTHWEST INTO THE PLAINS
WHERE IT WAS STALLING.
WEAK FLOW AND DRY CONDITIONS ALOFT HELPING TO KEEP CIRRUS FROM
UPSTREAM CONVECTION FROM MAKING INTO THE FORECAST AREA EARLY THIS
MORNING. A GRADUAL INCREASE IN CIRRUS EXPECTED TODAY AS THE
APPROACHING TROUGH INCREASES FLOW ALOFT. OTHERWISE SCATTERED HIGH
BASED CUMULUS EXPECTED TO DEVELOP DURING THE AFTERNOON.
WITH THE APPROACHING COLD FRONT SLOWING ACROSS THE OHIO VALLEY...AND
DEEP LAYER MOISTURE REMAINING TO THE NORTHWEST THROUGH THE DAY...DO
NOT ANTICIPATE CONVECTIVE DEVELOPMENT ACROSS THE AREA. HAVE RETAINED
A 20 PERCENT CHANCE FOR LATE AFTERNOON THUNDERSTORMS TO SNEAK INTO
THE NORTHWEST ZONES FROM PENNSYLVANIA AS STORM MOTIONS SHOULD BE
AROUND 290 DEGREES. THANKS FOR THE COLLABORATION SPC!
WITH THE THERMAL RIDGE AHEAD OF THE BAROCLINIC ZONE NEARING THE
REGION...HIGHS SHOULD BE NEAR 90F.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
SHORTWAVE TROUGH BEGINS LIFTING INTO NEW ENGLAND
TONIGHT...SUGGESTING BAROCLINIC ZONE SHOULD BE SLOW TO APPROACH FROM
THE NORTH.
MCV FROM ONGOING CENTRAL ILLINOIS CONVECTION IS THE WILD CARD. AT
THIS TIME ANTICIPATE THIS FEATURE TO GET CAUGHT UP IN THE MEAN FLOW
OF THE UPPER TROUGH...AND COULD IMPACT THE NORTHERN ZONES
TONIGHT...WHERE 21Z SREF INDICATE A CHANCE OF 250 J/KG OF MUCAPE.
LACK OF CONFIDENCE OF THE MCV TRACK AND AMOUNT OF ELEVATED
INSTABILITY HAS LEFT CHANCE POPS ACROSS THE NORTHERN ZONE FOR NOW.
OTHERWISE...EXPECT A WARMER NIGHT AND LIGHT SOUTHERLY FLOW AHEAD OF
THE COLD FRONT.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AN UPPER TROUGH WILL DEEPEN AS IT PUSHES EAST ACROSS THE OHIO
VALLEY TOWARDS THE EASTERN SEABOARD. A STALLED SURFACE FRONTAL
BOUNDARY ACROSS THE MID ATLANTIC WILL LEAD TO A WET HOLIDAY
WEEKEND. THE FRONT WILL ARRIVE OVER THE AREA BY FRIDAY AFTERNOON
AND TAKE RESIDENCE SOMEWHERE IN THE VICINITY OF THE MASON DIXON
LINE THROUGH SUNDAY BEFORE DISSIPATING ON MONDAY. SEVERAL WEAK AND
DIFFICULT TO TIME IMPULSES WILL DEVELOP AND RIDE EAST ALONG THE
FRONT. THIS WILL KEEP CHANCE TO LIKELY POPS THROUGH AT LEAST
MONDAY. SEVERE THREAT WILL HIGHLY DEPEND ON THE PLACEMENT OF THE
FRONT...WITH STRONGEST STORMS IN THE WARM SECTOR. FOR FRIDAY...THE
REGION REMAINS UNDER A DAY 2 SEE TEXT AREA WITH SPC. THERE IS SOME
SHEAR AND MINOR TO MODERATE INSTABILITY WHICH COULD STRENGTHEN
WITH ANY MORNING TO EARLY AFTERNOON SUN. STRONG TO SEVERE STORMS
ARE POSSIBLE...WITH DAMAGING WINDS AS THE PRIMARY THREAT.
SATURDAY AND SUNDAY WILL NOT BE MUCH BETTER...WITH HIGHEST POPS ON
SATURDAY. WILL NEED TO START WATCHING FOR MORE TRAINING STORMS WITH
HEAVY RAINFALL AND POSSIBLE FLOODING BEGINNING SATURDAY AS
PRECIPITABLE WATER VALUES INCREASE. HPC QPF 5 DAY GRAPHICS INDICATE
WIDESPREAD 2 TO 3 INCHES BY MONDAY EVENING.
THE FRONT WILL BE GONE LATE MONDAY...BUT HIGH PRESSURE OFF THE
SOUTHEAST COAST WILL FEED PLENTY OF WARM AND HUMID AIR ACROSS THE
REGION...MAINTAINING SLIGHT CHANCE TO CHANCE POPS THROUGH THE
REMAINDER OF THE FORECAST PERIOD.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
SOUTHWESTERLY WINDS AND INCREASING UPPER LEVEL CLOUDS ANTICIPATED
TODAY AHEAD OF A COLD FRONT. SCATTERED HIGH BASED CUMULUS SHOULD
ALSO DEVELOP FOR THE AFTERNOON MUCH LIKE YESTERDAY. THERE IS AN
OUTSIDE CHANCE THAT CONVECTION MAY IMPACT NORTHERN TERMINALS
TONIGHT...HOWEVER WITH THE TRACK OF THE UPPER LEVEL FEATURE...IT IS
MORE LIKELY TO AFFECT SITES TO THE NORTH. HAVE LEFT MENTION OF
CONVECTION OUT OF THE TAFS FOR NOW.
A WEAK COLD FRONT WILL STALL OVER THE MID ATLANTIC FRIDAY THROUGH
MONDAY...BRINGING PERIODS OF SHOWERS AND THUNDERSTORMS THROUGH THE
HOLIDAY WEEKEND. CEILINGS AND VISIBILITIES WILL OFTEN FALL TO MVFR
CRITERIA...WITH OCCASIONAL IFR POSSIBLE WITHIN STRONGER STORMS AND
HEAVY RAIN.
&&
.MARINE...
SOUTHERLY WINDS NEAR SMALL CRAFT CRITERIA HAVE DECREASED EARLY
THIS MORNING...ALLOWING THE ADVISORY TO BE CANCELLED. A BETTER
OPPORTUNITY FOR SOUTHERLY CHANNELING SMALL CRAFT ADVISORY CRITERIA
WINDS ANTICIPATED TONIGHT...AHEAD OF A COLD FRONT APPROACHING FROM
THE NORTH.
A WEAK COLD FRONT WILL STALL OVER THE MID ATLANTIC FRIDAY THROUGH
MONDAY...BRINGING PERIODS OF SHOWERS AND THUNDERSTORMS THROUGH THE
HOLIDAY WEEKEND. THE STRONGER STORMS WILL BE CAPABLE OF PRODUCING
WIND GUSTS IN EXCESS OF 30 KNOTS. WIND DIRECTION THROUGH THE WEEKEND
IS UNCERTAIN GIVEN THE SEMI-STATIONARY BOUNDARY SETTING UP SOMEWHERE
NEAR THE MASON DIXON LINE...THIS IS ESPECIALLY TRUE FOR THE NORTHERN
CHESAPEAKE BAY.
WHILE THE FRONT WILL DISSIPATE EARLY NEXT WEEK...SOUTHERLY WINDS
WILL BRING A WARM AND HUMID AIR AIRMASS TO THE REGION THROUGH THE
REMAINDER OF THE FORECAST PERIOD. THEREFORE...SLIGHT CHANCE TO
CHANCE POPS WILL REMAIN ESPECIALLY FOR AFTERNOON AND EVENING
CONVECTION.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM EDT
FRIDAY FOR ANZ531>534.
&&
$$
SYNOPSIS...SAR
NEAR TERM...ROGOWSKI
SHORT TERM...ROGOWSKI
LONG TERM...SAR
AVIATION...ROGOWSKI/SAR
MARINE...ROGOWSKI/SAR
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
815 PM EDT FRI JUL 4 2008
UPDATED FOR 00Z AVIATION DISCUSSION
.SHORT TERM (TONIGHT AND SATURDAY)...
DRY AND QUIET SHORT TERM PERIOD...AS RIDGE REMAINS OVER WRN NA AND
TROUGH CONTINUES OVER THE NE US. AT THE SFC...BROAD HIGH PRESSURE
IS PRESENTLY LOCATED OVER THE SOUTHERN GREAT LKS REGION. FARTHER
SOUTH...FRONTAL BOUNDARY IS STRETCHED ACROSS THE MID ATLANTIC
STATES AND ALONG THE OHIO RIVER VALLEY...WHICH IS KICKING OFF
SCATTERED SHOWERS AND THUNDERSTORMS. OVER THE CANADIAN
ROCKIES...LOW IS BEGINNING TO INTENSIFY AND DRAG A COLD FRONT
ACROSS WRN MONTANA...WHICH WILL BRING THE NEXT CHANCE OF RAIN TO
THE AREA NEAR THE BEGINNING OF THE WORK WEEK. CLOSER TO
HOME...CUMULUS DEVELOPED OVER MOST OF THE WRN GREAT LKS
REGION...AS DAYTIME HEATING TAPPED AN AREA OF LIMITED MOISTURE
BETWEEN H850-800 SEEN ON REGIONAL TAMDAR SOUNDINGS.
AREA WILL REMAIN UNDER THE INFLUENCE OF THE HIGH PUSHING INTO THE
SRN GREAT LKS TONIGHT...WHICH WILL PROVIDE ANOTHER PLEASANT NIGHT
FOR THE REGION. AS THE HIGH CONTINUES TO SLIDE TO THE ESE...LIGHT
SWLY WINDS WILL KEEP TEMPERATURES FROM DROPPING AS LOW AS LAST
NIGHT...WHERE A FEW INTERIOR COOP AND RAWS SITES REACHED THE UPPER
30S. EXISTING LOW FORECAST LOOKED GOOD...SO ONLY MADE MINOR
ADJUSTMENTS AND KEPT LOWS BELOW GUIDANCE.
ON SATURDAY...LOW IN SRN CANADA AND COLD FRONT WORKING INTO THE
NRN PLAINS WILL GRADUALLY STRENGTHEN THE PRESSURE GRADIENT OVER
THE WESTERN GREAT LAKES AND BRING A LITTLE STRONGER SW WINDS TO
THE AREA. THIS SHOULD LIMIT LAKE BREEZE DEVELOPMENT ALONG THE SERN
LK SUPERIOR SHORELINE. H850-800 TEMPS WILL ALSO BE ON THE INCREASE
TOMORROW...RISING FROM AROUND 10-11C TODAY TO AROUND 12-13C.
MIXING OUT TO THAT LEVEL WILL BRING HIGHS IN THE LOWER 80S ACROSS
MOST OF THE AREA. LK MI SHORELINE IS THE EXCEPTION...WHERE COOLER
WATER TEMPS...MID 50S OVER THE NRN PART OF THE LK...WILL KEEP THE
TEMPS AROUND 70. WITH THE WARMER TEMPS...THERE IS A SLIGHT CONCERN
FOR FIRE WEATHER...BUT WITH DEWPOINTS IN THE LOW 50S...RH VALUES
SHOULD REMAIN IN THE 30S. ALSO...DIURNAL CU WILL DEVELOP AGAIN
TOMORROW...WITH BEST COVERAGE OVER THE WRN PART OF UPPER MI...AS
MOISTURE STREAMS NWD.
&&
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
SAT NIGHT...SW WINDS SHOULD BE STRONG ENOUGH TO KEEP TEMPS FROM
FALLING OFF AS MUCH WITH MIN READINGS FROM THE MID 50S EAST TO MID
60S WEST...ESPECIALLY WHERE DOWNSLOPE FLOW PREVAILS.
SUN INTO SUN NIGHT...THE 12Z NAM AND GFS AND SREF MEAN WERE IN
REASONABLE AGREEMENT WITH THE STRENGTH/TIMING OF THE WEAK MID/UPPER
LEVEL SHORTWAVE TROUGH AND THE SURFACE FRONT MOVING THROUGH THE
UPPER GREAT LAKES. FCST POPS REFLECT THE TREND TOWARD FASTER
MOVEMENT OF THE SYSTEM THROUGH THE AREA AND MAY HAVE TO BE BUMPED UP
EVEN FURTHER IF LATER RUNS REMAIN CONSISTENT. FCST MAX TEMPS INTO
THE LOW TO MID 80S ALONG WITH DEWPOINTS CLIMBING TO THE LOWER 60S
OVER THE WEST HALF WOULD GIVE MLCAPE VALUES INTO THE 1000-1500 J/KG
RANGE. HOWEVER...0-6KM BULK SHEAR VALUES AROUND 30KT WOULD BE
MARGINAL TO SUPPORT ORGANIZED/SEVERE CONVECTION SUN AFTERNOON INTO
SUN EVENING.
MON AND INTO TUE...TIMING UNCERTAINTY REMAINS...BUT WEAK HIGH PRES
IN THE WAKE OF THE SHRTWV MAY BRING AN EARLY END TO THE SHRA/TSRA
MONDAY WITH POTENTIAL FOR DRYING BY AFTERNOON. ALTHOUGH THE 12Z GFS
WAS AFFECTED BY CONVECTIVE FEEDBACK WITH AN OVERDEVELOPED SHRTWV AND
SFC TROF...THE UKMET AND ECMWF ALSO SUGGEST ANOTHER SHORTWAVE AND
SFC WAVE WILL AFFECT THE WRN LAKES KEEPING SHRA/TSRA CHANCES
GOING...ESPECIALLY OVER THE SOUTH AND EAST...CLOSEST TO THE GREATER
INSTABILITY...PER 00Z ECMWF.
WED THROUGH FRI...UNCERTAINTY INCREASES WITH TRANSITION TO ZONAL
PATTERN AND DIFFICULTY RESOLVING WEAK SHRTWVS THAT MAY TRIGGER PCPN.
SO...LOWER END CHANCE POPS WERE MAINTAINED. TEMPS ARE EXPECTED TO
CLIMB FROM SEASONAL AVERAGES MIDWEEK TO WARMER THAN NORMAL BY FRI.
&&
.AVIATION (FOR THE 00Z TAF ISSUANCE)...
VFR CONDITIONS WILL CONTINUE AT BOTH SITES THROUGH THE TAF PERIOD.
EXPECT DIURNAL SCATTERED CUMULUS TO FORM AGAIN BY LATE SATURDAY
MORNING.
&&
.MARINE...
HIGH PRESSURE OVER THE CENTRAL GREAT LAKES WILL KEEP WINDS LESS
THAN 20 KNOTS TONIGHT AND SATURDAY. AS A LOW PRESSURE SYSTEM MOVES
EAST ACROSS SOUTHERN CANADA ON SATURDAY NIGHT AND
SUNDAY...SOUTHWEST WINDS WILL STRENGTHEN...BUT ONLY A FEW GUSTS TO
25 KNOTS ARE EXPECTED. WINDS WILL SHIFT TO THE NORTH BEHIND THE
FRONT ON SUNDAY NIGHT...THEN WEAKEN AS WEAK HIGH PRESSURE MOVES
OVER THE WESTERN GREAT LAKES THROUGH WEDNESDAY. OVERALL...WINDS
WILL BE LESS THAN 20 KNOTS FOR MOST OF THE PERIOD.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...JLB
AVIATION...JV
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
415 PM EDT FRI JUL 4 2008
.SHORT TERM (TONIGHT AND SATURDAY)...
DRY AND QUIET SHORT TERM PERIOD...AS RIDGE REMAINS OVER WRN NA AND
TROUGH CONTINUES OVER THE NE US. AT THE SFC...BROAD HIGH PRESSURE
IS PRESENTLY LOCATED OVER THE SOUTHERN GREAT LKS REGION. FARTHER
SOUTH...FRONTAL BOUNDARY IS STRETCHED ACROSS THE MID ATLANTIC
STATES AND ALONG THE OHIO RIVER VALLEY...WHICH IS KICKING OFF
SCATTERED SHOWERS AND THUNDERSTORMS. OVER THE CANADIAN
ROCKIES...LOW IS BEGINNING TO INTENSIFY AND DRAG A COLD FRONT
ACROSS WRN MONTANA...WHICH WILL BRING THE NEXT CHANCE OF RAIN TO
THE AREA NEAR THE BEGINNING OF THE WORK WEEK. CLOSER TO
HOME...CUMULUS DEVELOPED OVER MOST OF THE WRN GREAT LKS
REGION...AS DAYTIME HEATING TAPPED AN AREA OF LIMITED MOISTURE
BETWEEN H850-800 SEEN ON REGIONAL TAMDAR SOUNDINGS.
AREA WILL REMAIN UNDER THE INFLUENCE OF THE HIGH PUSHING INTO THE
SRN GREAT LKS TONIGHT...WHICH WILL PROVIDE ANOTHER PLEASANT NIGHT
FOR THE REGION. AS THE HIGH CONTINUES TO SLIDE TO THE ESE...LIGHT
SWLY WINDS WILL KEEP TEMPERATURES FROM DROPPING AS LOW AS LAST
NIGHT...WHERE A FEW INTERIOR COOP AND RAWS SITES REACHED THE UPPER
30S. EXISTING LOW FORECAST LOOKED GOOD...SO ONLY MADE MINOR
ADJUSTMENTS AND KEPT LOWS BELOW GUIDANCE.
ON SATURDAY...LOW IN SRN CANADA AND COLD FRONT WORKING INTO THE
NRN PLAINS WILL GRADUALLY STRENGTHEN THE PRESSURE GRADIENT OVER
THE WESTERN GREAT LAKES AND BRING A LITTLE STRONGER SW WINDS TO
THE AREA. THIS SHOULD LIMIT LAKE BREEZE DEVELOPMENT ALONG THE SERN
LK SUPERIOR SHORELINE. H850-800 TEMPS WILL ALSO BE ON THE INCREASE
TOMORROW...RISING FROM AROUND 10-11C TODAY TO AROUND 12-13C.
MIXING OUT TO THAT LEVEL WILL BRING HIGHS IN THE LOWER 80S ACROSS
MOST OF THE AREA. LK MI SHORELINE IS THE EXCEPTION...WHERE COOLER
WATER TEMPS...MID 50S OVER THE NRN PART OF THE LK...WILL KEEP THE
TEMPS AROUND 70. WITH THE WARMER TEMPS...THERE IS A SLIGHT CONCERN
FOR FIRE WEATHER...BUT WITH DEWPOINTS IN THE LOW 50S...RH VALUES
SHOULD REMAIN IN THE 30S. ALSO...DIURNAL CU WILL DEVELOP AGAIN
TOMORROW...WITH BEST COVERAGE OVER THE WRN PART OF UPPER MI...AS
MOISTURE STREAMS NWD.
&&
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
SAT NIGHT...SW WINDS SHOULD BE STRONG ENOUGH TO KEEP TEMPS FROM
FALLING OFF AS MUCH WITH MIN READINGS FROM THE MID 50S EAST TO MID
60S WEST...ESPECIALLY WHERE DOWNSLOPE FLOW PREVAILS.
SUN INTO SUN NIGHT...THE 12Z NAM AND GFS AND SREF MEAN WERE IN
REASONABLE AGREEMENT WITH THE STRENGTH/TIMING OF THE WEAK MID/UPPER
LEVEL SHORTWAVE TROUGH AND THE SURFACE FRONT MOVING THROUGH THE
UPPER GREAT LAKES. FCST POPS REFLECT THE TREND TOWARD FASTER
MOVEMENT OF THE SYSTEM THROUGH THE AREA AND MAY HAVE TO BE BUMPED UP
EVEN FURTHER IF LATER RUNS REMAIN CONSISTENT. FCST MAX TEMPS INTO
THE LOW TO MID 80S ALONG WITH DEWPOINTS CLIMBING TO THE LOWER 60S
OVER THE WEST HALF WOULD GIVE MLCAPE VALUES INTO THE 1000-1500 J/KG
RANGE. HOWEVER...0-6KM BULK SHEAR VALUES AROUND 30KT WOULD BE
MARGINAL TO SUPPORT ORGANIZED/SEVERE CONVECTION SUN AFTERNOON INTO
SUN EVENING.
MON AND INTO TUE...TIMING UNCERTAINTY REMAINS...BUT WEAK HIGH PRES
IN THE WAKE OF THE SHRTWV MAY BRING AN EARLY END TO THE SHRA/TSRA
MONDAY WITH POTENTIAL FOR DRYING BY AFTERNOON. ALTHOUGH THE 12Z GFS
WAS AFFECTED BY CONVECTIVE FEEDBACK WITH AN OVERDEVELOPED SHRTWV AND
SFC TROF...THE UKMET AND ECMWF ALSO SUGGEST ANOTHER SHORTWAVE AND
SFC WAVE WILL AFFECT THE WRN LAKES KEEPING SHRA/TSRA CHANCES
GOING...ESPECIALLY OVER THE SOUTH AND EAST...CLOSEST TO THE GREATER
INSTABILITY...PER 00Z ECMWF.
WED THROUGH FRI...UNCERTAINTY INCREASES WITH TRANSITION TO ZONAL
PATTERN AND DIFFICULTY RESOLVING WEAK SHRTWVS THAT MAY TRIGGER PCPN.
SO...LOWER END CHANCE POPS WERE MAINTAINED. TEMPS ARE EXPECTED TO
CLIMB FROM SEASONAL AVERAGES MIDWEEK TO WARMER THAN NORMAL BY FRI.
&&
.AVIATION (FOR THE 18Z TAF ISSUANCE)...
VFR CONDITIONS WILL CONTINUE AT BOTH SITES THROUGH THE TAF PERIOD.
ONLY EXPECT FEW-SCT DIURNAL CUMULUS THIS AFTERNOON AND LATE
MORNING TOMORROW.
&&
.MARINE...
HIGH PRESSURE OVER THE CENTRAL GREAT LAKES WILL KEEP WINDS LESS
THAN 20 KNOTS TONIGHT AND SATURDAY. AS A LOW PRESSURE SYSTEM MOVES
EAST ACROSS SOUTHERN CANADA ON SATURDAY NIGHT AND
SUNDAY...SOUTHWEST WINDS WILL STRENGTHEN...BUT ONLY A FEW GUSTS TO
25 KNOTS ARE EXPECTED. WINDS WILL SHIFT TO THE NORTH BEHIND THE
FRONT ON SUNDAY NIGHT...THEN WEAKEN AS WEAK HIGH PRESSURE MOVES
OVER THE WESTERN GREAT LAKES THROUGH WEDNESDAY. OVERALL...WINDS
WILL BE LESS THAN 20 KNOTS FOR MOST OF THE PERIOD.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...JLB
AVIATION...SRF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
232 PM EDT FRI JUL 4 2008
LATEST UPDATE...LONG TERM...
.SYNOPSIS...(200 PM EDT FRI JUL 4 2008)
HIGH PRESSURE OVER THE GREAT LAKES WILL DRIFT SLOWLY EAST THROUGH
SUNDAY. AS A RESULT DRY WEATHER IS EXPECTED WITH MAINLY CLEAR SKIES
AND SEASONABLE TO SLIGHTLY BELOW NORMAL TEMPERATURES.
LOW PRESSURE WILL APPROACH THE REGION ON MONDAY AS A WARMER AND MORE
HUMID AIR MOVES INTO THE REGION. SCATTERED SHOWERS AND THUNDERSTORMS
ARE EXPECTED TO ACCOMPANY THE LOW PRESURE SYSTEM AS IT MOVES THROUGH
THE AREA MONDAY INTO TUESDAY.
&&
.SHORT TERM...(200 PM EDT FRI JUL 4 2008)
(TODAY THROUGH SUNDAY)
LOOKING AT THREAT FOR SOME RIVER/VALLEY FOG EARLY SAT. IDEAL
RADIATIONAL COOLING SCENARIO WITH VERY LIGHT WINDS TONIGHT. TEMPS
WILL FALL QUICKLY AT SUNSET AND WITH A VERY WET GROUND EXPECT TO SEE
AREAS OF FOG DEVELOP AT DAYBREAK. EXPECT ANY FOG WILL BE SHALLOW
AND WILL DISSIPATE BY 9 AM ON SATURDAY.
GOOD CONSENSUS ON WARMING TREND AS HIGH SLOWLY MOVES EAST OF THE
AREA. SATURDAY SHOULD BE ABOUT 5 DEGREES WARMER THAN TODAY WITH
SUNDAY ANOTHER FEW DEGREES WARMER YET. SUNDAY MORNING ALSO A
CHALLENGE CONCERNING AMOUNT OF RADIATIONAL COOLING WITH MODEST SOUTH
FLOW OFF SFC. ALSO ANOTHER FOG THREAT WITH MOISTURE ADVECTION ALSO
BEGINNING W INCREASING S FLOW.
&&
.LONG TERM...(232 PM EDT FRI JUL 4 2008)
(SUNDAY NIGHT THROUGH FRIDAY)
MID RANGE MODELS HAVE DECENT AGREEMENT WITH SOME MINOR DIFFERENCES
IN TIMING AND LOCATION OF PRECIPITATION. LEANING TOWARD THE ECMWF
SOLUTION AND INTRODUCED PRECIPITATION LATE SUNDAY NIGHT AHEAD OF A
COLD FRONT.
THE FRONT SLOWS AND ALMOST STALLS ON MONDAY WITH AN MCS FORECAST TO
FORM ACROSS THE NORTHERN IOWA/SOUTHERN MINNESOTA AREA ON MONDAY
EVENING AND MOVE EAST... ARRIVING ACROSS OUR FORECAST AREA OVERNIGHT.
SCATTERED OR ISOLATED SHOWERS AND THUNDERSTORMS LINGER FOR TUESDAY
INTO WEDNESDAY BEFORE THE FRONT FINALLY PUSHES SOUTH WITH SURFACE
HIGH AND DRIER WEATHER BUILDING IN ON THURSDAY. ADDED SLIGHT CHANCE
OF THUNDERSTORMS FRIDAY TO MATCH NEIGHBORS... THOUGH I AM FAR FROM
CONFIDENT OF ANYTHING HAPPENING.
&&
.MARINE...(200 PM EDT FRI JUL 4 2008)
LAND-LAKE BREEZE CIRCULATIONS WILL DOMINATE OVER THROUGH SUNDAY WITH
HIGH PRESSURE OVERHEAD. OFFSHORE WINDS AROUND 5 KTS OVERNIGHT WITH
ONSHORE WINDS LOCALLY 10 KTS THIS AFTERNOON AND SATURDAY.
&&
.AVIATION...(200 PM EDT FRI JUL 4 2008)
EXPECT MAINLY VFR CONDITIONS NEXT SEVERAL DAYS. EXCEPTION WILL BE
PERIOD OF RIVER/VALLEY FOG DEVELOPING ABOUT 09Z - DISSIPATING BY 13Z
SAT MORNING. WINDS WILL BE MAINLY ENE AND LESS THAN 10KTS THIS
AFTN...EXCEPT WITHIN 1 TO 5 MILES OF THE COAST WHERE THERE WILL BE A
LAKE BREEZE (ONSHORE WIND AT 05 KTS) WITH A DEPTH OF ABOUT 1000 FT.
SMALL AIRCRAFT MAY ENCOUNTER SOME WINDSHEAR IN THE VICINITY OF THE
LAKE BREEZE FRONT THROUGH 00Z. SAME SCENARIO SATURDAY WITH LIGHT
EAST WINDS EXCEPT FOR ONSHORE LAKE BREEZE PENETRATING 10 TO 20 MILES
INLAND BY LATE AFTERNOON.
&&
.HYDROLOGY...(1130 AM EDT FRI JUL 4 2008)
RISES ON STREAMS AND RIVERS ACROSS SOUTHERN LOWER MICHIGAN WILL
REMAIN WELL BELOW FLOOD STAGE. DRY WEATHER IS EXPECTED THROUGH EARLY
MONDAY AND THIS WILL ALLOW THE RIVERS TO FALL... AHEAD OF THE NEXT
POTENTIAL RAIN PRODUCER ARRIVING MONDAY AFTERNOON.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS: COBB
SHORT TERM: COBB
LONG TERM: IOD
MARINE: COBB
AVIATION: COBB
HYDROLOGY: IOD
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
200 PM EDT FRI JUL 4 2008
LATEST UPDATE...AVIATION...SYNOPIS...SHORTTERM...MARINE...
.SYNOPSIS...(200 PM EDT FRI JUL 4 2008)
HIGH PRESSURE OVER THE GREAT LAKES WILL DRIFT SLOWLY EAST THROUGH
SUNDAY. AS A RESULT DRY WEATHER IS EXPECTED WITH MAINLY CLEAR SKIES
AND SEASONABLE TO SLIGHTLY BELOW NORMAL TEMPERATURES.
LOW PRESSURE WILL APPROACH THE REGION ON MONDAY AS A WARMER AND MORE
HUMID AIR MOVES INTO THE REGION. SCATTERED SHOWERS AND THUNDERSTORMS
ARE EXPECTED TO ACCOMPANY THE LOW PRESURE SYSTEM AS IT MOVES THROUGH
THE AREA MONDAY INTO TUESDAY.
&&
.SHORT TERM...(200 PM EDT FRI JUL 4 2008)
(TODAY THROUGH SUNDAY)
LOOKING AT THREAT FOR SOME RIVER/VALLEY FOG EARLY SAT. IDEAL
RADIATIONAL COOLING SCENARIO WITH VERY LIGHT WINDS TONIGHT. TEMPS
WILL FALL QUICKLY AT SUNSET AND WITH A VERY WET GROUND EXPECT TO SEE
AREAS OF FOG DEVELOP AT DAYBREAK. EXPECT ANY FOG WILL BE SHALLOW
AND WILL DISSIPATE BY 9 AM ON SATURDAY.
GOOD CONSENSUS ON WARMING TREND AS HIGH SLOWLY MOVES EAST OF THE
AREA. SATURDAY SHOULD BE ABOUT 5 DEGREES WARMER THAN TODAY WITH
SUNDAY ANOTHER FEW DEGREES WARMER YET. SUNDAY MORNING ALSO A
CHALLENGE CONCERNING AMOUNT OF RADIATIONAL COOLING WITH MODEST SOUTH
FLOW OFF SFC. ALSO ANOTHER FOG THREAT WITH MOISTURE ADVECTION ALSO
BEGINNING W INCREASING S FLOW.
&&
.LONG TERM...(348 AM EDT FRI JUL 4 2008)
(SUNDAY NIGHT THROUGH THURSDAY)
WENT WITH THE GFS ENSEMBLE AND KEPT SUNDAY NIGHT DRY FOR NOW...BUT
THE ECWMF HINTS THAT SOME PRECIP COULD ARRIVE LATE SUNDAY NIGHT AS
FRONT MOVES INTO NORTHERN LOWER MICHIGAN. THE FRONT SLOWS AND ALMOST
STALLS ON MONDAY AS BOTH THE ECMWF AND GFS NOW IMPLY AN MCS WILL
FORM ACROSS NORTHERN IOWA/SOUTHERN MINNESOTA AREA ON MONDAY NIGHT
AND MOVE EAST...ARRIVING ACROSS OUR FORECAST AREA BY 12Z TUESDAY.
TWEAKED POPS UP FOR MONDAY NIGHT TO ACCOUNT FOR THIS.
SCATTERED OR ISOLATED SHOWERS AND THUNDERSTORMS LINGER FOR TUESDAY
AND WEDNESDAY BEFORE THE FRONT FINALLY PUSHES SOUTH WITH SFC HIGH
AND DRIER WEATHER BUILDING IN ON THURSDAY.
&&
.MARINE...(200 PM EDT FRI JUL 4 2008)
LAND-LAKE BREEZE CIRCULATIONS WILL DOMINATE OVER THROUGH SUNDAY WITH
HIGH PRESSURE OVERHEAD. OFFSHORE WINDS AROUND 5 KTS OVERNIGHT WITH
ONSHORE WINDS LOCALLY 10 KTS THIS AFTERNOON AND SATURDAY.
&&
.AVIATION...(200 PM EDT FRI JUL 4 2008)
EXPECT MAINLY VFR CONDITIONS NEXT SEVERAL DAYS. EXCEPTION WILL BE
PERIOD OF RIVER/VALLEY FOG DEVELOPING ABOUT 09Z - DISSIPATING BY 13Z
SAT MORNING. WINDS WILL BE MAINLY ENE AND LESS THAN 10KTS THIS
AFTN...EXCEPT WITHIN 1 TO 5 MILES OF THE COAST WHERE THERE WILL BE A
LAKE BREEZE (ONSHORE WIND AT 05 KTS) WITH A DEPTH OF ABOUT 1000 FT.
SMALL AIRCRAFT MAY ENCOUNTER SOME WINDSHEAR IN THE VICINITY OF THE
LAKE BREEZE FRONT THROUGH 00Z. SAME SCENARIO SATURDAY WITH LIGHT
EAST WINDS EXCEPT FOR ONSHORE LAKE BREEZE PENETRATING 10 TO 20 MILES
INLAND BY LATE AFTERNOON.
&&
.HYDROLOGY...(1130 AM EDT FRI JUL 4 2008)
RISES ON STREAMS AND RIVERS ACROSS SOUTHERN LOWER MICHIGAN WILL
REMAIN WELL BELOW FLOOD STAGE. DRY WEATHER IS EXPECTED THROUGH EARLY
MONDAY AND THIS WILL ALLOW THE RIVERS TO FALL... AHEAD OF THE NEXT
POTENTIAL RAIN PRODUCER ARRIVING MONDAY AFTERNOON.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS: COBB
SHORT TERM: COBB
LONG TERM: OSTUNO
MARINE: COBB
AVIATION: COBB
HYDROLOGY: IOD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
247 PM EDT FRI JUL 4 2008
.SYNOPSIS...
HIGH PRESSURE CENTERED OVER THE ATLANTIC WILL ALLOW MOISTURE TO
INCREASE ACROSS CENTRAL NORTH CAROLINA THIS WEEKEND. THE INCREASED
MOISTURE COMBINED WITH AN UPPER LEVEL TROUGH TO THE WEST WILL RESULT
IN AN INCREASED CHANCE OF SCATTERED SHOWERS AND THUNDERSTORMS
THROUGH THE END WEEKEND AND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 200 PM FRIDAY...
THERE ARE MIXED SIGNALS REGARDING CONVECTIVE CHANCES FOR THE REST OF
TODAY INTO TONIGHT. FIRST OFF... ISOLATED CONVECTION HAS DEVELOPED
IN THE FOOTHILLS AND AS FAR EAST AS THE SW PIEDMONT AS OF 2 PM. WEAK
LOW LEVEL CONVERGENCE ASSOCIATED WITH A LEE TROUGH AND MLCAPES OF
500-1000 J/KG APPEAR TO BE THE REASONS FOR THE CONVECTIVE
INITIATION. IT IS DIFFICULT TO ASCERTAIN THE EVOLUTION OF CONVECTION
THIS AFTERNOON AS DEWPOINTS BEGIN TO LOWER WITH DEEP MIXING
ESTABLISHED. DEWPOINTS WILL DROP INTO THE UPPER 50S AND LOWER 60S
THROUGH THE REST OF THE AFTERNOON...AND THIS WILL PREVENT CAPE
VALUES FROM INCREASING ANY MORE. WILL SHOW A 20 POP (ISOLATED
COVERAGE) FOR THE WESTERN PIEDMONT TO ACCOUNT FOR CURRENT ACTIVITY
ON RADAR. FURTHER EAST...WILL LEAVE THE REST OF THE AFTERNOON DRY AS
CAPPING EVIDENT THIS MORNING ON THE MHX SOUNDING SHOULD BE
SUFFICIENT TO PREVENT DEVELOPMENT AS MODELS DO NOT ERODE THE CAP
UNTIL LATER THIS EVENING.
THERE APPEARS TO BE A BETTER CHANCE AT CONVECTION...ESPECIALLY OVER
NORTHWEST PORTIONS OF THE CWA THIS EVENING. AS MIXING IS
LOST...BOUNDARY LAYER MOISTURE WILL INCREASE AS SFC DEWPOINTS CLIMB
BACK INTO THE UPPER 60S TO NEAR 70. IN ADDITION...A WEAK SHORT WAVE
OVER THE TN VALLEY... NOTED WITH THE COOL POOL OVER NASHVILLE THIS
MORNING...WILL SKIRT THE NW PIEDMONT THIS EVENING. THIS MAY PRODUCE
ADDITIONAL CONVECTION IN THE FOOTHILLS THAT COULD THEN WORK ITS WAY
INTO THE NW PIEDMONT. OUTFLOW BOUNDARIES WILL ALSO PLAY AN IMPORTANT
ROLE IN DETERMINING CONVECTIVE EVOLUTION THIS EVENING...AND THAT IS
VERY HARD TO DETAIL AT THIS JUNCTURE. WILL MAINTAIN THE THEME OF THE
PREVIOUS FORECAST... WITH POPS INCREASING TO LOW END CHANCE IN AREAS
NORTH AND WEST... ONLY SHOWING A SLIGHT CHANCE FURTHER SOUTHEAST
WHERE THERE APPEARS TO BE NO APPRECIABLE UPPER LEVEL LIFT. AREAS IN
THE SOUTHEAST WILL HAVE TO RELY ALMOST SOLELY ON OUTFLOW BOUNDARIES
MOVING INTO THE AREA. MOST CONVECTION SHOULD DIMINISH AFTER 06Z WITH
BOUNDARY LAYER STABILIZATION AND LACK OF SIGNIFICANT UPPER LEVEL
SUPPORT. LOWS VERY MILD TONIGHT WITH AT LEAST PARTLY CLOUDY SKIES
AND A PERSISTENT SW WIND. LOWS 69-73.
AN INCREASE IN CONVECTIVE COVERAGE IS EXPECTED FOR SATURDAY. A BROAD
MID AND UPPER LEVEL TROUGH OVER THE OHIO AND TN VALLEYS WILL KEEP A
SOUTHWEST FLOW OVER OUR REGION. PRECIPITABLE WATERS RESPOND WITH
VALUES CLIMBING TO NEAR 2 INCHES BY SATURDAY AFTERNOON. AT LEAST
SOME MODEST UPPER LEVEL DIVERGENCE SETS UP OVER NORTHWESTER PORTIONS
OF THE AREA SATURDAY AFTERNOON IN RESPONSE TO THE AREA BECOME
POSITIONED IN THE RIGHT ENTRANCE REGION OF AN UPPER JET. THE JET
POSITION IS MUCH MORE FAVORABLE ON THE NAM AS COMPARED TO THE GFS.
AT THIS JUNCTURE IT IS HARD TO PINPOINT ANY LOCATIONS MORE FAVORED
FOR CONVECTIVE COVERAGE. IF THE NAM IS CORRECT IN ITS JET
PLACEMENT...THEN THE NW PIEDMONT WOULD SEE A GREATER COVERAGE.
HOWEVER...THIS IS NOT CERTAIN AND WOULD PREFER TO SHOW A HIGH END
CHANCE (SCATTERED COVERAGE) ACROSS THE ENTIRE AREA. DEEP LAYER SHEAR
IS EXPECTED TO BE ONLY AROUND 20 KT... SO CONVECTIVE MODE SHOULD
REMAIN PULSE IN NATURE. THEREFORE...OUTFLOW BOUNDARY INTERACTIONS
WILL ONCE AGAIN GO A LONG WAY IN DETERMINING STORM COVERAGE AND
LOCATION. WITH LIGHT WIND FIELDS ALOFT AND STORM MOTIONS OF ONLY
AROUND 10 KT... THE STRONGER THUNDERSTORMS WILL BE EFFICIENT RAIN
PRODUCERS GIVEN THE HIGH PRECIPITABLE WATER VALUES. AN ISOLATED
SEVERE STORM CANNOT BE RULED OUT... BUT LACK OF SHEAR WILL PRECLUDE
A WIDESPREAD EVENT. GREATER CLOUD COVERAGE AND RAIN CHANCES WILL
HOLD TEMPS DOWN COMPARED TO TODAY. HIGHS 87-92.
HAVE A HAPPY AND SAFE FOURTH OF JULY!
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 230 PM FRIDAY...
SUMMARY:
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED
THROUGHOUT THE SHORT TERM FORECAST PERIOD (INCLUDING THE OVERNIGHT
HOURS)...ALTHOUGH ACTIVITY SHOULD BE MOST NUMEROUS DURING AFTERNOON
PEAK HEATING ON SUN/MON. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE
WITH ANY THUNDERSTORMS. ISOLATED SEVERE THUNDERSTORMS WILL BE
POSSIBLE PRIMARILY DURING THE AFTERNOON HOURS OF SUNDAY...ALTHOUGH A
FEW STRONG TO SEVERE STORMS WILL BE POSSIBLE MONDAY AFTERNOON AS
WELL.
SATURDAY NIGHT THROUGH SUNDAY NIGHT:
STILL EXPECT SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS DURING
THIS PERIOD WITH MID/UPPER LEVEL TROUGHING JUST TO OUR WEST OVER THE
OH/TN VALLEYS...KEEPING A MOIST SOUTHERLY/SW FLOW THROUGHOUT THE
COLUMN OVER THE CAROLINAS. FCST SOUNDINGS ACROSS CENTRAL NC SHOW
FAIRLY IMPRESSIVE PWAT VALUES IN THE 1.75-2.00" RANGE THROUGHOUT
THIS PERIOD. WITH PWAT VALUES THIS HIGH AND DEWPOINTS LIKELY IN THE
UPPER 60S TO LOWER 70S...INSTABILITY WILL MOST DEFINITELY BE PRESENT
AND ACCOUNTED FOR. AS FAR AS LIFT IS CONCERNED...BEING LOCATED JUST
DOWNSTREAM OF THE MID/UPPER TROUGH TO THE WEST...WE WILL BE IN A
FAVORABLE REGION FOR UPPER LEVEL DIVERGENCE...IN ADDITION TO
SHORTWAVE IMPULSES ROUNDING THE BASE OF THE TROUGH AND LIFTING
NE/ENE OVER THE CAROLINAS. TOUGH TO PICK OUT ANY AREA IN PARTICULAR
FOR AN ENHANCED CHANCE OF SHOWERS/STORMS SINCE THIS MAY DEPEND ON
THE EXACT TIMING/TRACK OF ANY SHORTWAVE IMPULSES AND/OR WHERE THE
BETTER UPPER LEVEL DIVERGENCE IS LOCATED. THEREFORE...HAVE DECIDED
TO ADVERTISE MID CHANCE POPS (40%) ACROSS THE ENTIRE FORECAST AREA
SAT NIGHT WHEN INSTABILITY WILL BE WEAKER...WITH 50% CHANCES DURING
THE DAY SUNDAY WHEN DIURNAL HEATING WILL ALLOW FOR BETTER
INSTABILITY...AND LOW CHANCE (30%) POPS SUNDAY NIGHT AS THE
MID/UPPER LEVEL TROUGH JUST TO OUR WEST BEGINS TO SHOW SIGNS OF
WEAKENING/DEAMPLIFYING. LOW TEMPS SAT/SUN NIGHT SHOULD BE IN THE
NORMAL TO SLIGHTLY ABOVE NORMAL RANGE IN THE UPPER 60S TO LOWER 70S.
HIGH TEMPS ON SUNDAY SHOULD HAVE NO PROBLEM MAKING IT INTO THE
MID/UPPER 80S...AND WHETHER OR NOT SOME LOCATIONS SEE LOWER 90S WILL
DEPEND ON HOW MUCH CLOUD COVER AND CONVECTION IS PRESENT.
GIVEN THE HIGH PWAT VALUES AND SCATTERED TO OCCASIONALLY NUMEROUS
SHOWERS AND THUNDERSTORMS EXPECTED...LOCALLY HEAVY RAINFALL CAN BE
EXPECTED...WITH A POTENTIAL FOR FLOODING...PARTICULARLY IN URBAN
AREAS. AS FAR AS SEVERE WEATHER IS CONCERNED...LOW/MID LEVEL FLOW IS
PROGGED TO GENERALLY BE AT OR BELOW 20 KNOTS THROUGH 700MB...
INCREASING TO MAYBE 25-30 KNOTS IN THE MID-LEVELS SUNDAY AFTERNOON.
THIS MAY MAKE IT DIFFICULT FOR AN ORGANIZED SEVERE WEATHER THREAT TO
DEVELOP...AND EXPECT THAT ANY SEVERE STORMS WOULD BE OF THE
PULSE/ISOLATED VARIETY...WITH A PRIMARY THREAT OF DAMAGING WINDS IN
THE FORM OF WET MICROBURSTS AND HAIL UP TO THE SIZE OF QUARTERS.
MONDAY AND MONDAY NIGHT:
THE MID/UPPER LEVEL TROUGH IS PROGGED TO CONTINUE TO WEAKEN AND
DEAMPLIFY DURING THE DAY MONDAY AS IT LIFTS ENE/NE ACROSS THE LOWER
MID-ATLANTIC. ALTHOUGH UPPER LEVEL LIFT WILL BE WEAKENING...FCST
SOUNDINGS CONTINUE TO SHOW VERY MOIST PWAT VALUES IN THE 1.75" TO
2.00" RANGE...WITH PLENTY OF AVAILABLE INSTABILITY. HAVE THEREFORE
DECIDED TO ADVERTISE MID-CHANCE (40%) POPS ACROSS THE ENTIRE
FORECAST AREA DURING THE DAYTIME PEAK-HEATING HOURS. A FEW STORMS
MAY BRIEFLY BECOME STRONG TO SEVERE DURING THE AFTERNOON...WITH A
PRIMARY THREAT OF DAMAGING WINDS AND LARGE HAIL. WILL KEEP A SLIGHT
CHANCE (20%) OF SHOWERS/STORMS MONDAY NIGHT GIVEN CONTINUED HIGH
PWAT VALUES AND THE LIKELY PRESENCE OF ELEVATED INSTABILITY. THE
UPPER LEVEL PATTERN BECOMES MORE UNIDIRECTIONAL BY THIS
TIME...HOWEVER...ANY ONGOING ACTIVITY MAY KEEP GOING WELL PAST
SUNSET WITH THE HELP OF MESOSCALE BOUNDARIES...AND THIS IS WHY THE
SLIGHT CHANCE WILL BE LEFT IN FOR MONDAY NIGHT. HIGH TEMPS ON MONDAY
SHOULD BE SIMILAR TO SUNDAY...GENERALLY IN THE MID/UPPER 80S WITH A
FEW LOCATIONS MAKING IT INTO THE LOWER 90S IF GIVEN ENOUGH SUNSHINE.
LOW TEMPS MONDAY NIGHT SIMILAR TO PREVIOUS NIGHTS...RANGING FROM THE
UPPER 60S TO LOWER 70S. -VINCENT
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 245 PM FRIDAY...
THE BERMUDA RIDGE ATTEMPTS TO RETROGRADE BACK TOWARD THE SOUTHEAST
COAST AND FL THROUGH MID WEEK...WHILE SHORTWAVE ENERGY MOVING ACROSS
THE US/CANADA BORDER ALLOWS THE WESTERLIES TO DIP A BIT SOUTHWARD
INTO THE NRN GREAT LAKES/ST LAWRENCE VALLEY/NORTHEAST. VERY LITTLE
CHANGES AT THE SURFACE...WITH THE ATLANTIC-CENTERED SURFACE HIGH
HOLDING IN PLACE AND EXTENDING WSW INTO THE SOUTHEAST COASTAL
SECTIONS...WITH A PERSISTENT PIEDMONT TROUGH OVER CENTRAL/WRN NC AND
PWAT VALUES REMAINING IN THE 120-140% OF NORMAL RANGE. AS MUCH AS I
WOULD LIKE TO BE ABLE TO DISCERN ONE DAY AS BEING BETTER THAN
ANOTHER FOR SCATTERED MAINLY AFTERNOON/EVENING SHOWERS AND
STORMS...AT THIS RANGE AND WITH MODEL VARIATION IN THE DETAILS...IT
REMAINS NEARLY IMPOSSIBLE. WILL CONTINUE WITH LOW CHANCE (30%)
POPS...MAINLY AFTERNOON AND EVENING...TUESDAY THROUGH FRIDAY.
GFS/ECMWF THICKNESSES REMAIN NEAR NORMAL AND TEMPERATURES SHOULD RUN
CLOSE TO NORMAL THROUGH THE PERIOD AS WELL. -GIH/VINCENT
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 2 PM FRIDAY...
IN GENERAL... VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD...WITH
THE EXCEPTION BEING THE POTENTIAL FOR ISOLATED TO SCATTERED
CONVECTION. FOR THE REST OF THE DAY THROUGH TONIGHT... BEST
POTENTIAL FOR CONVECTION WILL BE AT THE TRIAD TERMINALS. IN THIS
REGION...THE MID LEVEL CAP IS WEAKER AND LOW LEVEL CONVERGENCE
COMBINED WITH A WEAK UPPER LEVEL DISTURBANCE MOVING EAST FROM THE TN
VALLEY WILL SUPPORT THE DEVELOPMENT OF CONVECTION THROUGH LATE THIS
AFTERNOON AND INTO TONIGHT. RESULTANT OUTFLOW BOUNDARIES EMANATING
FROM CONVECTION OVER THE FOOTHILLS MAY ALSO BECOME A TRIGGER FOR
CONVECTIVE DEVELOPMENT. TOO MUCH UNCERTAINTY REMAINS REGARDING
COVERAGE AND TIMING OF CONVECTION...SO WILL INCLUDE A CB AT GSO/INT
AND AS FAR EAST AS RDU FOR THIS EVENING THROUGH LATE TONIGHT. ANY
CONVECTION ACROSS THE AREA SHOULD WANE DURING THE PREDAWN HOURS.
WINDS AT 2 KFT WILL INCREASE TO AROUND 25 KT OVERNIGHT. WHILE WE MAY
FALL SHORT OF EXACT LOW LEVEL WIND SHEAR CRITERIA...AT LEAST 15-20
KT OF LLWS WILL BE PRESENT AFTER MIDNIGHT WHICH COULD AFFECT SMALLER
AIRCRAFT AND GENERAL AVIATION INTERESTS.
AREAL EXTENT OF CONVECTION WILL INCREASE ON SATURDAY AS THERE WILL
BE NO MID LEVEL CAP AND DEEP LAYER MOISTURE AND INSTABILITY IS
PLENTIFUL. EXPECT SCATTERED TO NUMEROUS THUNDERSTORMS TO AFFECT
CENTRAL NC STARTING ROUGHLY AROUND 16Z TOMORROW AND THIS ACTIVITY
WILL LIKELY PERSIST INTO SATURDAY NIGHT. WILL INTRODUCE CB AT 16Z AT
ALL TERMINALS TO ACCOUNT FOR THE CONVECTIVE POTENTIAL. OTHERWISE...
VFR CONDITIONS EXPECTED OUTSIDE CONVECTION.
CHANCES FOR DIURNAL CONVECTION WILL PERSIST THROUGH AT LEAST TUESDAY
OF NEXT WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JFB
NEAR TERM...JFB
SHORT TERM...VINCENT
LONG TERM...GIH/VINCENT
AVIATION...JFB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
235 PM EDT FRI JUL 4 2008
.SYNOPSIS...
HIGH PRESSURE CENTERED OVER THE ATLANTIC WILL ALLOW MOISTURE TO
INCREASE ACROSS CENTRAL NORTH CAROLINA THIS WEEKEND. THE INCREASED
MOISTURE COMBINED WITH AN UPPER LEVEL TROUGH TO THE WEST WILL RESULT
IN AN INCREASED CHANCE OF SCATTERED SHOWERS AND THUNDERSTORMS
THROUGH THE END WEEKEND AND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 200 PM FRIDAY...
THERE ARE MIXED SIGNALS REGARDING CONVECTIVE CHANCES FOR THE REST OF
TODAY INTO TONIGHT. FIRST OFF... ISOLATED CONVECTION HAS DEVELOPED
IN THE FOOTHILLS AND AS FAR EAST AS THE SW PIEDMONT AS OF 2 PM. WEAK
LOW LEVEL CONVERGENCE ASSOCIATED WITH A LEE TROUGH AND MLCAPES OF
500-1000 J/KG APPEAR TO BE THE REASONS FOR THE CONVECTIVE
INITIATION. IT IS DIFFICULT TO ASCERTAIN THE EVOLUTION OF CONVECTION
THIS AFTERNOON AS DEWPOINTS BEGIN TO LOWER WITH DEEP MIXING
ESTABLISHED. DEWPOINTS WILL DROP INTO THE UPPER 50S AND LOWER 60S
THROUGH THE REST OF THE AFTERNOON...AND THIS WILL PREVENT CAPE
VALUES FROM INCREASING ANY MORE. WILL SHOW A 20 POP (ISOLATED
COVERAGE) FOR THE WESTERN PIEDMONT TO ACCOUNT FOR CURRENT ACTIVITY
ON RADAR. FURTHER EAST...WILL LEAVE THE REST OF THE AFTERNOON DRY AS
CAPPING EVIDENT THIS MORNING ON THE MHX SOUNDING SHOULD BE
SUFFICIENT TO PREVENT DEVELOPMENT AS MODELS DO NOT ERODE THE CAP
UNTIL LATER THIS EVENING.
THERE APPEARS TO BE A BETTER CHANCE AT CONVECTION...ESPECIALLY OVER
NORTHWEST PORTIONS OF THE CWA THIS EVENING. AS MIXING IS
LOST...BOUNDARY LAYER MOISTURE WILL INCREASE AS SFC DEWPOINTS CLIMB
BACK INTO THE UPPER 60S TO NEAR 70. IN ADDITION...A WEAK SHORT WAVE
OVER THE TN VALLEY... NOTED WITH THE COOL POOL OVER NASHVILLE THIS
MORNING...WILL SKIRT THE NW PIEDMONT THIS EVENING. THIS MAY PRODUCE
ADDITIONAL CONVECTION IN THE FOOTHILLS THAT COULD THEN WORK ITS WAY
INTO THE NW PIEDMONT. OUTFLOW BOUNDARIES WILL ALSO PLAY AN IMPORTANT
ROLE IN DETERMINING CONVECTIVE EVOLUTION THIS EVENING...AND THAT IS
VERY HARD TO DETAIL AT THIS JUNCTURE. WILL MAINTAIN THE THEME OF THE
PREVIOUS FORECAST... WITH POPS INCREASING TO LOW END CHANCE IN AREAS
NORTH AND WEST... ONLY SHOWING A SLIGHT CHANCE FURTHER SOUTHEAST
WHERE THERE APPEARS TO BE NO APPRECIABLE UPPER LEVEL LIFT. AREAS IN
THE SOUTHEAST WILL HAVE TO RELY ALMOST SOLELY ON OUTFLOW BOUNDARIES
MOVING INTO THE AREA. MOST CONVECTION SHOULD DIMINISH AFTER 06Z WITH
BOUNDARY LAYER STABILIZATION AND LACK OF SIGNIFICANT UPPER LEVEL
SUPPORT. LOWS VERY MILD TONIGHT WITH AT LEAST PARTLY CLOUDY SKIES
AND A PERSISTENT SW WIND. LOWS 69-73.
AN INCREASE IN CONVECTIVE COVERAGE IS EXPECTED FOR SATURDAY. A BROAD
MID AND UPPER LEVEL TROUGH OVER THE OHIO AND TN VALLEYS WILL KEEP A
SOUTHWEST FLOW OVER OUR REGION. PRECIPITABLE WATERS RESPOND WITH
VALUES CLIMBING TO NEAR 2 INCHES BY SATURDAY AFTERNOON. AT LEAST
SOME MODEST UPPER LEVEL DIVERGENCE SETS UP OVER NORTHWESTER PORTIONS
OF THE AREA SATURDAY AFTERNOON IN RESPONSE TO THE AREA BECOME
POSITIONED IN THE RIGHT ENTRANCE REGION OF AN UPPER JET. THE JET
POSITION IS MUCH MORE FAVORABLE ON THE NAM AS COMPARED TO THE GFS.
AT THIS JUNCTURE IT IS HARD TO PINPOINT ANY LOCATIONS MORE FAVORED
FOR CONVECTIVE COVERAGE. IF THE NAM IS CORRECT IN ITS JET
PLACEMENT...THEN THE NW PIEDMONT WOULD SEE A GREATER COVERAGE.
HOWEVER...THIS IS NOT CERTAIN AND WOULD PREFER TO SHOW A HIGH END
CHANCE (SCATTERED COVERAGE) ACROSS THE ENTIRE AREA. DEEP LAYER SHEAR
IS EXPECTED TO BE ONLY AROUND 20 KT... SO CONVECTIVE MODE SHOULD
REMAIN PULSE IN NATURE. THEREFORE...OUTFLOW BOUNDARY INTERACTIONS
WILL ONCE AGAIN GO A LONG WAY IN DETERMINING STORM COVERAGE AND
LOCATION. WITH LIGHT WIND FIELDS ALOFT AND STORM MOTIONS OF ONLY
AROUND 10 KT... THE STRONGER THUNDERSTORMS WILL BE EFFICIENT RAIN
PRODUCERS GIVEN THE HIGH PRECIPITABLE WATER VALUES. AN ISOLATED
SEVERE STORM CANNOT BE RULED OUT... BUT LACK OF SHEAR WILL PRECLUDE
A WIDESPREAD EVENT. GREATER CLOUD COVERAGE AND RAIN CHANCES WILL
HOLD TEMPS DOWN COMPARED TO TODAY. HIGHS 87-92.
HAVE A HAPPY AND SAFE FOURTH OF JULY!
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 230 PM FRIDAY...
SUMMARY:
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED
THROUGHOUT THE SHORT TERM FORECAST PERIOD (INCLUDING THE OVERNIGHT
HOURS)...ALTHOUGH ACTIVITY SHOULD BE MOST NUMEROUS DURING AFTERNOON
PEAK HEATING ON SUN/MON. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE
WITH ANY THUNDERSTORMS. ISOLATED SEVERE THUNDERSTORMS WILL BE
POSSIBLE PRIMARILY DURING THE AFTERNOON HOURS OF SUNDAY...ALTHOUGH A
FEW STRONG TO SEVERE STORMS WILL BE POSSIBLE MONDAY AFTERNOON AS
WELL.
SATURDAY NIGHT THROUGH SUNDAY NIGHT:
STILL EXPECT SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS DURING
THIS PERIOD WITH MID/UPPER LEVEL TROUGHING JUST TO OUR WEST OVER THE
OH/TN VALLEYS...KEEPING A MOIST SOUTHERLY/SW FLOW THROUGHOUT THE
COLUMN OVER THE CAROLINAS. FCST SOUNDINGS ACROSS CENTRAL NC SHOW
FAIRLY IMPRESSIVE PWAT VALUES IN THE 1.75-2.00" RANGE THROUGHOUT
THIS PERIOD. WITH PWAT VALUES THIS HIGH AND DEWPOINTS LIKELY IN THE
UPPER 60S TO LOWER 70S...INSTABILITY WILL MOST DEFINITELY BE PRESENT
AND ACCOUNTED FOR. AS FAR AS LIFT IS CONCERNED...BEING LOCATED JUST
DOWNSTREAM OF THE MID/UPPER TROUGH TO THE WEST...WE WILL BE IN A
FAVORABLE REGION FOR UPPER LEVEL DIVERGENCE...IN ADDITION TO
SHORTWAVE IMPULSES ROUNDING THE BASE OF THE TROUGH AND LIFTING
NE/ENE OVER THE CAROLINAS. TOUGH TO PICK OUT ANY AREA IN PARTICULAR
FOR AN ENHANCED CHANCE OF SHOWERS/STORMS SINCE THIS MAY DEPEND ON
THE EXACT TIMING/TRACK OF ANY SHORTWAVE IMPULSES AND/OR WHERE THE
BETTER UPPER LEVEL DIVERGENCE IS LOCATED. THEREFORE...HAVE DECIDED
TO ADVERTISE MID CHANCE POPS (40%) ACROSS THE ENTIRE FORECAST AREA
SAT NIGHT WHEN INSTABILITY WILL BE WEAKER...WITH 50% CHANCES DURING
THE DAY SUNDAY WHEN DIURNAL HEATING WILL ALLOW FOR BETTER
INSTABILITY...AND LOW CHANCE (30%) POPS SUNDAY NIGHT AS THE
MID/UPPER LEVEL TROUGH JUST TO OUR WEST BEGINS TO SHOW SIGNS OF
WEAKENING/DEAMPLIFYING. LOW TEMPS SAT/SUN NIGHT SHOULD BE IN THE
NORMAL TO SLIGHTLY ABOVE NORMAL RANGE IN THE UPPER 60S TO LOWER 70S.
HIGH TEMPS ON SUNDAY SHOULD HAVE NO PROBLEM MAKING IT INTO THE
MID/UPPER 80S...AND WHETHER OR NOT SOME LOCATIONS SEE LOWER 90S WILL
DEPEND ON HOW MUCH CLOUD COVER AND CONVECTION IS PRESENT.
GIVEN THE HIGH PWAT VALUES AND SCATTERED TO OCCASIONALLY NUMEROUS
SHOWERS AND THUNDERSTORMS EXPECTED...LOCALLY HEAVY RAINFALL CAN BE
EXPECTED...WITH A POTENTIAL FOR FLOODING...PARTICULARLY IN URBAN
AREAS. AS FAR AS SEVERE WEATHER IS CONCERNED...LOW/MID LEVEL FLOW IS
PROGGED TO GENERALLY BE AT OR BELOW 20 KNOTS THROUGH 700MB...
INCREASING TO MAYBE 25-30 KNOTS IN THE MID-LEVELS SUNDAY AFTERNOON.
THIS MAY MAKE IT DIFFICULT FOR AN ORGANIZED SEVERE WEATHER THREAT TO
DEVELOP...AND EXPECT THAT ANY SEVERE STORMS WOULD BE OF THE
PULSE/ISOLATED VARIETY...WITH A PRIMARY THREAT OF DAMAGING WINDS IN
THE FORM OF WET MICROBURSTS AND HAIL UP TO THE SIZE OF QUARTERS.
MONDAY AND MONDAY NIGHT:
THE MID/UPPER LEVEL TROUGH IS PROGGED TO CONTINUE TO WEAKEN AND
DEAMPLIFY DURING THE DAY MONDAY AS IT LIFTS ENE/NE ACROSS THE LOWER
MID-ATLANTIC. ALTHOUGH UPPER LEVEL LIFT WILL BE WEAKENING...FCST
SOUNDINGS CONTINUE TO SHOW VERY MOIST PWAT VALUES IN THE 1.75" TO
2.00" RANGE...WITH PLENTY OF AVAILABLE INSTABILITY. HAVE THEREFORE
DECIDED TO ADVERTISE MID-CHANCE (40%) POPS ACROSS THE ENTIRE
FORECAST AREA DURING THE DAYTIME PEAK-HEATING HOURS. A FEW STORMS
MAY BRIEFLY BECOME STRONG TO SEVERE DURING THE AFTERNOON...WITH A
PRIMARY THREAT OF DAMAGING WINDS AND LARGE HAIL. WILL KEEP A SLIGHT
CHANCE (20%) OF SHOWERS/STORMS MONDAY NIGHT GIVEN CONTINUED HIGH
PWAT VALUES AND THE LIKELY PRESENCE OF ELEVATED INSTABILITY. THE
UPPER LEVEL PATTERN BECOMES MORE UNIDIRECTIONAL BY THIS
TIME...HOWEVER...ANY ONGOING ACTIVITY MAY KEEP GOING WELL PAST
SUNSET WITH THE HELP OF MESOSCALE BOUNDARIES...AND THIS IS WHY THE
SLIGHT CHANCE WILL BE LEFT IN FOR MONDAY NIGHT. HIGH TEMPS ON MONDAY
SHOULD BE SIMILAR TO SUNDAY...GENERALLY IN THE MID/UPPER 80S WITH A
FEW LOCATIONS MAKING IT INTO THE LOWER 90S IF GIVEN ENOUGH SUNSHINE.
LOW TEMPS MONDAY NIGHT SIMILAR TO PREVIOUS NIGHTS...RANGING FROM THE
UPPER 60S TO LOWER 70S. -VINCENT
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 340 AM FRIDAY...
THE BERMUDA RIDGE ATTEMPTS TO RETROGRADE BACK TOWARD THE SOUTHEAST
COAST AND FL THROUGH MID WEEK... WHILE SHORTWAVE ENERGY MOVING
ACROSS THE US/CANADA BORDER ALLOWS THE WESTERLIES TO DIP A BIT
SOUTHWARD INTO THE NRN GREAT LAKES/ST LAWRENCE VALLEY/NORTHEAST.
VERY LITTLE CHANGES AT THE SURFACE... WITH THE ATLANTIC-CENTERED
SURFACE HIGH HOLDING IN PLACE AND EXTENDING WSW INTO THE SOUTHEAST
COASTAL SECTIONS... WITH A PERSISTENT PIEDMONT TROUGH OVER
CENTRAL/WRN NC AND PRECIPITABLE WATER REMAINING IN THE 120-140% OF
NORMAL RANGE. INASMUCH AS I WOULD LIKE TO BE ABLE TO DISCERN ONE DAY
AS BEING BETTER THAN ANOTHER FOR SCATTERED MAINLY AFTERNOON/EVENING
SHOWERS AND STORMS... AT THIS RANGE AND WITH MODEL VARIATION IN THE
DETAILS... IT REMAINS NEARLY IMPOSSIBLE. WILL CONTINUE WITH CHANCE
POPS... MAINLY AFTERNOON AND EVENING... TUESDAY THROUGH THURSDAY.
GFS/ECMWF THICKNESSES REMAIN NEAR NORMAL AND TEMPERATURES SHOULD RUN
CLOSE TO NORMAL THROUGH THE PERIOD AS WELL. -GIH
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 2 PM FRIDAY...
IN GENERAL... VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD...WITH
THE EXCEPTION BEING THE POTENTIAL FOR ISOLATED TO SCATTERED
CONVECTION. FOR THE REST OF THE DAY THROUGH TONIGHT... BEST
POTENTIAL FOR CONVECTION WILL BE AT THE TRIAD TERMINALS. IN THIS
REGION...THE MID LEVEL CAP IS WEAKER AND LOW LEVEL CONVERGENCE
COMBINED WITH A WEAK UPPER LEVEL DISTURBANCE MOVING EAST FROM THE TN
VALLEY WILL SUPPORT THE DEVELOPMENT OF CONVECTION THROUGH LATE THIS
AFTERNOON AND INTO TONIGHT. RESULTANT OUTFLOW BOUNDARIES EMANATING
FROM CONVECTION OVER THE FOOTHILLS MAY ALSO BECOME A TRIGGER FOR
CONVECTIVE DEVELOPMENT. TOO MUCH UNCERTAINTY REMAINS REGARDING
COVERAGE AND TIMING OF CONVECTION...SO WILL INCLUDE A CB AT GSO/INT
AND AS FAR EAST AS RDU FOR THIS EVENING THROUGH LATE TONIGHT. ANY
CONVECTION ACROSS THE AREA SHOULD WANE DURING THE PREDAWN HOURS.
WINDS AT 2 KFT WILL INCREASE TO AROUND 25 KT OVERNIGHT. WHILE WE MAY
FALL SHORT OF EXACT LOW LEVEL WIND SHEAR CRITERIA...AT LEAST 15-20
KT OF LLWS WILL BE PRESENT AFTER MIDNIGHT WHICH COULD AFFECT SMALLER
AIRCRAFT AND GENERAL AVIATION INTERESTS.
AREAL EXTENT OF CONVECTION WILL INCREASE ON SATURDAY AS THERE WILL
BE NO MID LEVEL CAP AND DEEP LAYER MOISTURE AND INSTABILITY IS
PLENTIFUL. EXPECT SCATTERED TO NUMEROUS THUNDERSTORMS TO AFFECT
CENTRAL NC STARTING ROUGHLY AROUND 16Z TOMORROW AND THIS ACTIVITY
WILL LIKELY PERSIST INTO SATURDAY NIGHT. WILL INTRODUCE CB AT 16Z AT
ALL TERMINALS TO ACCOUNT FOR THE CONVECTIVE POTENTIAL. OTHERWISE...
VFR CONDITIONS EXPECTED OUTSIDE CONVECTION.
CHANCES FOR DIURNAL CONVECTION WILL PERSIST THROUGH AT LEAST TUESDAY
OF NEXT WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JFB
NEAR TERM...JFB
SHORT TERM...VINCENT
LONG TERM...HARTFIELD
AVIATION...JFB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
226 PM EDT FRI JUL 4 2008
.SYNOPSIS...
HIGH PRESSURE CENTERED OVER THE ATLANTIC WILL ALLOW MOISTURE TO
INCREASE ACROSS CENTRAL NORTH CAROLINA THIS WEEKEND. THE INCREASED
MOISTURE COMBINED WITH AN UPPER LEVEL TROUGH TO THE WEST WILL RESULT
IN AN INCREASED CHANCE OF SCATTERED SHOWERS AND THUNDERSTORMS
THROUGH THE END WEEKEND AND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 2 PM FRIDAY...
THERE ARE MIXED SIGNALS REGARDING CONVECTIVE CHANCES FOR THE REST OF
TODAY INTO TONIGHT. FIRST OFF... ISOLATED CONVECTION HAS DEVELOPED
IN THE FOOTHILLS AND AS FAR EAST AS THE SW PIEDMONT AS OF 2 PM. WEAK
LOW LEVEL CONVERGENCE ASSOCIATED WITH A LEE TROUGH AND MLCAPES OF
500-1000 J/KG APPEAR TO BE THE REASONS FOR THE CONVECTIVE
INITIATION. IT IS DIFFICULT TO ASCERTAIN THE EVOLUTION OF CONVECTION
THIS AFTERNOON AS DEWPOINTS BEGIN TO LOWER WITH DEEP MIXING
ESTABLISHED. DEWPOINTS WILL DROP INTO THE UPPER 50S AND LOWER 60S
THROUGH THE REST OF THE AFTERNOON...AND THIS WILL PREVENT CAPE
VALUES FROM INCREASING ANY MORE. WILL SHOW A 20 POP (ISOLATED
COVERAGE) FOR THE WESTERN PIEDMONT TO ACCOUNT FOR CURRENT ACTIVITY
ON RADAR. FURTHER EAST...WILL LEAVE THE REST OF THE AFTERNOON DRY AS
CAPPING EVIDENT THIS MORNING ON THE MHX SOUNDING SHOULD BE
SUFFICIENT TO PREVENT DEVELOPMENT AS MODELS DO NOT ERODE THE CAP
UNTIL LATER THIS EVENING.
THERE APPEARS TO BE A BETTER CHANCE AT CONVECTION...ESPECIALLY OVER
NORTHWEST PORTIONS OF THE CWA THIS EVENING. AS MIXING IS
LOST...BOUNDARY LAYER MOISTURE WILL INCREASE AS SFC DEWPOINTS CLIMB
BACK INTO THE UPPER 60S TO NEAR 70. IN ADDITION...A WEAK SHORT WAVE
OVER THE TN VALLEY... NOTED WITH THE COOL POOL OVER NASHVILLE THIS
MORNING...WILL SKIRT THE NW PIEDMONT THIS EVENING. THIS MAY PRODUCE
ADDITIONAL CONVECTION IN THE FOOTHILLS THAT COULD THEN WORK ITS WAY
INTO THE NW PIEDMONT. OUTFLOW BOUNDARIES WILL ALSO PLAY AN IMPORTANT
ROLE IN DETERMINING CONVECTIVE EVOLUTION THIS EVENING...AND THAT IS
VERY HARD TO DETAIL AT THIS JUNCTURE. WILL MAINTAIN THE THEME OF THE
PREVIOUS FORECAST... WITH POPS INCREASING TO LOW END CHANCE IN AREAS
NORTH AND WEST... ONLY SHOWING A SLIGHT CHANCE FURTHER SOUTHEAST
WHERE THERE APPEARS TO BE NO APPRECIABLE UPPER LEVEL LIFT. AREAS IN
THE SOUTHEAST WILL HAVE TO RELY ALMOST SOLELY ON OUTFLOW BOUNDARIES
MOVING INTO THE AREA. MOST CONVECTION SHOULD DIMINISH AFTER 06Z WITH
BOUNDARY LAYER STABILIZATION AND LACK OF SIGNIFICANT UPPER LEVEL
SUPPORT. LOWS VERY MILD TONIGHT WITH AT LEAST PARTLY CLOUDY SKIES
AND A PERSISTENT SW WIND. LOWS 69-73.
AN INCREASE IN CONVECTIVE COVERAGE IS EXPECTED FOR SATURDAY. A BROAD
MID AND UPPER LEVEL TROUGH OVER THE OHIO AND TN VALLEYS WILL KEEP A
SOUTHWEST FLOW OVER OUR REGION. PRECIPITABLE WATERS RESPOND WITH
VALUES CLIMBING TO NEAR 2 INCHES BY SATURDAY AFTERNOON. AT LEAST
SOME MODEST UPPER LEVEL DIVERGENCE SETS UP OVER NORTHWESTER PORTIONS
OF THE AREA SATURDAY AFTERNOON IN RESPONSE TO THE AREA BECOME
POSITIONED IN THE RIGHT ENTRANCE REGION OF AN UPPER JET. THE JET
POSITION IS MUCH MORE FAVORABLE ON THE NAM AS COMPARED TO THE GFS.
AT THIS JUNCTURE IT IS HARD TO PINPOINT ANY LOCATIONS MORE FAVORED
FOR CONVECTIVE COVERAGE. IF THE NAM IS CORRECT IN ITS JET
PLACEMENT...THEN THE NW PIEDMONT WOULD SEE A GREATER COVERAGE.
HOWEVER...THIS IS NOT CERTAIN AND WOULD PREFER TO SHOW A HIGH END
CHANCE (SCATTERED COVERAGE) ACROSS THE ENTIRE AREA. DEEP LAYER SHEAR
IS EXPECTED TO BE ONLY AROUND 20 KT... SO CONVECTIVE MODE SHOULD
REMAIN PULSE IN NATURE. THEREFORE...OUTFLOW BOUNDARY INTERACTIONS
WILL ONCE AGAIN GO A LONG WAY IN DETERMINING STORM COVERAGE AND
LOCATION. WITH LIGHT WIND FIELDS ALOFT AND STORM MOTIONS OF ONLY
AROUND 10 KT... THE STRONGER THUNDERSTORMS WILL BE EFFICIENT RAIN
PRODUCERS GIVEN THE HIGH PRECIPITABLE WATER VALUES. AN ISOLATED
SEVERE STORM CANNOT BE RULED OUT... BUT LACK OF SHEAR WILL PRECLUDE
A WIDESPREAD EVENT. GREATER CLOUD COVERAGE AND RAIN CHANCES WILL
HOLD TEMPS DOWN COMPARED TO TODAY. HIGHS 87-92.
HAVE A HAPPY AND SAFE FOURTH OF JULY!
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
AS OF 255 AM FRIDAY...
FOR SATURDAY NIGHT THROUGH SUNDAY NIGHT: IN SHORT... EXPECT
ON-AND-OFF SCATTERED TO NUMEROUS SHOWERS AND STORMS THROUGH THE
LATTER HALF OF THE WEEKEND... WITH PRECIPITABLE WATER REMAINING NEAR
150% OF NORMAL... BOUNDARY LAYER FLOW REMAINING CONFLUENT OUT OF THE
S AND SW KEEPING LOW LEVEL MOISTURE ELEVATED... AND THE MID LEVEL
TROUGH AXIS HOLDING TO OUR WEST. THE LIFTED CONDENSATION LEVEL
ACROSS THE AREA DROPS EARLY SATURDAY NIGHT AND REMAINS IN THE
900-970 MB RANGE THROUGH SUNDAY NIGHT. THIS YIELDS A DEEPENING
LCL-TO-FREEZING-LEVEL LAYER TO 3.5-3.8 KM WHICH FAVORS WARM RAIN
PROCESSES... AND SOME BANDS OF HEAVIER SHOWERS ARE POSSIBLE.
FORECAST SOUNDINGS SHOW MODERATE INSTABILITY PERSISTING... ALTHOUGH
THE DEEP LAYER SHEAR WILL BE MARGINAL AT AROUND 15-20 KTS... AND A
TIGHT LOW LEVEL JET APPEARS TO BE LACKING... SO THE POTENTIAL FOR
STRONG STORMS STILL LOOKS LIMITED BUT THIS WILL NEED TO BE WATCHED.
FURTHER COMPLICATING MATTERS STARTING SUNDAY IS THE DIVERGENT
SOLUTIONS OF THE NAM AND GFS... WITH THE FORMER CLOSING OFF A MID
LEVEL LOW NEAR MEMPHIS BY LATE SUNDAY WHILE THE LATTER HAS THE WEAK
TROUGH SLOWLY LIFTING OUT TO OUR NW. WHILE THE GFS IS INDEED
TRENDING SLOWLY WITH THE EJECTION OF THIS TROUGH... WHICH IS
REASONABLE CONSIDERING THE NORTHWARD RETREAT OF THE WESTERLIES...
THE NAM LOOKS TOO OVERDONE TOO FAR SOUTH. EITHER WAY... NC REMAINS
ON THE WET SIDE OF THIS TROUGH. HIGHS SUNDAY SHOULD BE JUST UNDER
CLIMATOLOGY WITH ABUNDANT CLOUD COVER. LOWS A CATEGORY ABOVE NORMAL
BOTH NIGHTS. -GIH
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 340 AM FRIDAY...
FOR MONDAY: IF THE GFS/ECMWF SOLUTION OF THE SLOW-MOVING YET
PROGRESSIVE TROUGH AXIS SHIFTING THROUGH THE CENTRAL APPALACHIANS
AND NW NC INTO THE NORTHEAST STATES LATE SUNDAY NIGHT THROUGH MONDAY
ENDS UP CORRECT... WE`RE STILL LIKELY TO SEE SCATTERED TO NUMEROUS
SHOWERS AND STORMS THROUGH MONDAY MORNING. THE GFS SHOWS CONTINUED
MODERATE INSTABILITY AND NORMALIZED CAPE (CAPE FROM LCL TO THE
EQUILIBRIUM LEVEL) EXCEEDS 0.2... FAVORING STRONG UPDRAFTS. WITH
DEEP LAYER SHEAR NEARING 30 KTS AS THE TROUGH AXIS SWEEPS BY TO OUR
NW AND WITH THE MID LEVELS DRYING OUT SOMEWHAT IN THE AFTERNOON...
WE COULD SEE A RISK OF A FEW STRONG STORMS IF THE EXPECTED MORNING
PRECIP AND CLOUDS DON`T HINDER AFTERNOON DESTABILIZATION. HIGHS
SHOULD BE NEAR NORMAL... IN THE UPPER 80S TO NEAR 90.
FOR THE REMAINDER OF THE PERIOD: THE BERMUDA RIDGE ATTEMPTS TO
RETROGRADE BACK TOWARD THE SOUTHEAST COAST AND FL THROUGH MID
WEEK... WHILE SHORTWAVE ENERGY MOVING ACROSS THE US/CANADA BORDER
ALLOWS THE WESTERLIES TO DIP A BIT SOUTHWARD INTO THE NRN GREAT
LAKES/ST LAWRENCE VALLEY/NORTHEAST. VERY LITTLE CHANGES AT THE
SURFACE... WITH THE ATLANTIC-CENTERED SURFACE HIGH HOLDING IN PLACE
AND EXTENDING WSW INTO THE SOUTHEAST COASTAL SECTIONS... WITH A
PERSISTENT PIEDMONT TROUGH OVER CENTRAL/WRN NC AND PRECIPITABLE
WATER REMAINING IN THE 120-140% OF NORMAL RANGE. INASMUCH AS I WOULD
LIKE TO BE ABLE TO DISCERN ONE DAY AS BEING BETTER THAN ANOTHER FOR
SCATTERED MAINLY AFTERNOON/EVENING SHOWERS AND STORMS... AT THIS
RANGE AND WITH MODEL VARIATION IN THE DETAILS... IT REMAINS NEARLY
IMPOSSIBLE. WILL CONTINUE WITH CHANCE POPS... MAINLY AFTERNOON AND
EVENING... TUESDAY THROUGH THURSDAY. GFS/ECMWF THICKNESSES REMAIN
NEAR NORMAL AND TEMPERATURES SHOULD RUN CLOSE TO NORMAL THROUGH THE
PERIOD AS WELL. -GIH
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 2 PM FRIDAY...
IN GENERAL... VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD...WITH
THE EXCEPTION BEING THE POTENTIAL FOR ISOLATED TO SCATTERED
CONVECTION. FOR THE REST OF THE DAY THROUGH TONIGHT... BEST
POTENTIAL FOR CONVECTION WILL BE AT THE TRIAD TERMINALS. IN THIS
REGION...THE MID LEVEL CAP IS WEAKER AND LOW LEVEL CONVERGENCE
COMBINED WITH A WEAK UPPER LEVEL DISTURBANCE MOVING EAST FROM THE TN
VALLEY WILL SUPPORT THE DEVELOPMENT OF CONVECTION THROUGH LATE THIS
AFTERNOON AND INTO TONIGHT. RESULTANT OUTFLOW BOUNDARIES EMANATING
FROM CONVECTION OVER THE FOOTHILLS MAY ALSO BECOME A TRIGGER FOR
CONVECTIVE DEVELOPMENT. TOO MUCH UNCERTAINTY REMAINS REGARDING
COVERAGE AND TIMING OF CONVECTION...SO WILL INCLUDE A CB AT GSO/INT
AND AS FAR EAST AS RDU FOR THIS EVENING THROUGH LATE TONIGHT. ANY
CONVECTION ACROSS THE AREA SHOULD WANE DURING THE PREDAWN HOURS.
WINDS AT 2 KFT WILL INCREASE TO AROUND 25 KT OVERNIGHT. WHILE WE MAY
FALL SHORT OF EXACT LOW LEVEL WIND SHEAR CRITERIA...AT LEAST 15-20
KT OF LLWS WILL BE PRESENT AFTER MIDNIGHT WHICH COULD AFFECT SMALLER
AIRCRAFT AND GENERAL AVIATION INTERESTS.
AREAL EXTENT OF CONVECTION WILL INCREASE ON SATURDAY AS THERE WILL
BE NO MID LEVEL CAP AND DEEP LAYER MOISTURE AND INSTABILITY IS
PLENTIFUL. EXPECT SCATTERED TO NUMEROUS THUNDERSTORMS TO AFFECT
CENTRAL NC STARTING ROUGHLY AROUND 16Z TOMORROW AND THIS ACTIVITY
WILL LIKELY PERSIST INTO SATURDAY NIGHT. WILL INTRODUCE CB AT 16Z AT
ALL TERMINALS TO ACCOUNT FOR THE CONVECTIVE POTENTIAL. OTHERWISE...
VFR CONDITIONS EXPECTED OUTSIDE CONVECTION.
CHANCES FOR DIURNAL CONVECTION WILL PERSIST THROUGH AT LEAST TUESDAY
OF NEXT WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JFB
NEAR TERM...JFB
SHORT TERM...HARTFIELD
LONG TERM...HARTFIELD
AVIATION...JFB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
135 PM EDT FRI JUL 4 2008
.SYNOPSIS...
HIGH PRESSURE CENTERED OVER THE ATLANTIC WILL CONTINUE TO EXTEND
WESTWARD INTO THE REGION THROUGH THE FOURTH OF JULY. MOISTURE WILL
CONTINUE TO INCREASE OVER THE AREA HEADING INTO THE WEEKEND...
LEADING TO AN INCREASING CHANCE OF SHOWERS AND STORMS.
&&
.NEAR TERM /THROUGH EARLY TONIGHT/...
AS OF 1045 AM FRIDAY...
12Z SOUNDING FROM GSO SHOWS THAT PRECIPITABLE WATERS CONTINUE TO
STEADILY RISE THIS MORNING WITH 1.14 INCHES PRESENT...ABOUT 90
PERCENT OF NORMAL. LAPSE RATES ARE ALSO VERY STEEP THROUGH 700
MB...BUT THEN WARM IN THE MID LEVELS WITH A BIT OF A CAP STILL
PRESENT. THE MHX SOUNDING FROM THIS MORNING SHOWS A MUCH STRONGER
CAP ABOVE 700 MB...WHILE THERE IS ESSENTIALLY NO CAP PRESENT AT RNK.
CLOUD COVER HAS BEEN MINIMAL THIS MORNING WITH JUST SOME MID AND
HIGH LEVEL CLOUDS PASSING BY. WITH ALL OF THE CONVECTION ASSOCIATED
WITH THE FRONT WELL TO OUR NORTH AND A MEAN SW FLOW... EXPECT MOST
DEBRIS CLOUDS TO REMAIN NORTH OF US THROUGH THIS AFTERNOON. WHILE WE
WILL SEE DIURNAL CUMULUS THIS AFTERNOON...HAVE A ADDED A DEGREE OR
TWO TO MAX TEMPS TO ACCOUNT FOR LESS CONVECTIVE DEBRIS AND LOW LEVEL
THICKNESSES REACHING ABOUT 10-15 M HIGHER THAN YESTERDAY. THIS
SHOULD GIVE LOW 90S NW PIEDMONT TO MID 90S ELSEWHERE THIS AFTERNOON.
ALTHOUGH DEWPOINTS ARE CURRENTLY IN THE UPPER 60S TO NEAR 70... THE
PRESENCE OF A DEEP MIXED LAYER THROUGH 700 MB WITH DRY AIR
PRESENT...SHOULD HELP DEWPOINTS TO MIX OUT TO THE UPPER 50S NW TO
LOW 60S IN THE COASTAL PLAIN. SO...ALTHOUGH IT WILL BE HOT...LOWER
HUMIDITY VALUES WILL KEEP IT FROM FEELING OPPRESSIVE.
REGARDING CONVECTIVE POTENTIAL... LOWERING DEWPOINTS THIS AFTERNOON
ALONG WITH THE PRESENCE OF A MID LEVEL CAP EFFECTIVELY LIMIT THE
AMOUNT OF MIXED LAYER CAPE TODAY... GENERALLY WELL UNDER A 1000
J/KG. THUS...EXPECT MOST OF THE DAY TO BE CONVECTION FREE. AGREE
WITH THE PREVIOUS FORECAST THAT PRECIP CHANCES WILL BEGIN TO
INCREASE IN THE NW EARLY THIS EVENING AS MASS LOW LEVEL CONVERGENCE
INCREASES AND THE MID LEVEL CAP IS REMOVED. ALSO...OUTFLOW
BOUNDARIES WILL LIKELY PLAY A ROLE THIS EVENING...AS THEY EMANATE
FROM CONVECTION OVER THE MOUNTAINS AND FOOTHILLS... WHICH WILL BE IN
A BETTER REGIME FOR CONVECTION THIS AFTERNOON. A WEAK 500 MB WAVE
OVER NASHVILLE (-12C THERE COMPARED TO TEMPS 2-3C WARMER ELSEWHERE)
WILL ALSO MOVE EAST TODAY AND HELP CONVECTION INITIATE IN THE
MOUNTAINS. WILL MAINTAIN THE PREVIOUS FORECAST OF CHANCE POPS
ENTERING THE NORTHWEST PIEDMONT THIS EVENING. IF WE CAN REALIZE
CONVECTION OVER THE NW THIS EVENING...THEN A FEW STORMS COULD BE
STRONG WITH GUSTY WINDS...AS THE STEEP LAPSE RATES EVIDENT ON THE
GSO SOUNDING WILL ALLOW FOR EXCELLENT EVAPORATIVE COOLING. THIS IS
HANDLED WELL IN THE CURRENT HAZARDOUS WEATHER OUTLOOK.
HAVE A HAPPY AND SAFE FOURTH OF JULY!
&&
.SHORT TERM /LATE TONIGHT THROUGH SUNDAY NIGHT/...
AS OF 255 AM FRIDAY...
FOR LATE TONIGHT THROUGH SATURDAY: THE UPPER JET CORE NOW STRETCHING
FROM THE DAKOTAS DOWN TO NRN MO WILL ROUND THE TROUGH BASE TONIGHT
INTO SATURDAY MORNING... PLACING NC IN ITS RIGHT ENTRANCE REGION.
MEANWHILE THE DEEP LAYER SHEAR BEGINS TO INCREASE... RISING TO 20-25
KTS FROM 06Z-12Z TONIGHT... SO A FEW STORMS EVEN LATER TONIGHT COULD
BECOME STRONG. GIVEN MODEL CONSENSUS THAT PRECIPITABLE WATER WILL
APPROACH 1.9-2.0 INCHES BY SATURDAY MORNING AS WE TAP INTO THE
HIGHER GULF-SOURCE MOISTURE... THE PRESENCE OF AN 850 MB THETA-E
RIDGE FROM AL/GA THROUGH NC... AND WITH THE INCOMING FORCING FOR
ASCENT DUE TO THE INCREASING UPPER LEVEL DIVERGENCE... RISING POPS
INTO THE HIGH CHANCE/LOW LIKELY RANGE SATURDAY STILL LOOKS GOOD AND
REASONABLE... ALTHOUGH I DON`T FORESEE A NONSTOP SOAKING LASTING ALL
DAY... BUT RATHER PERIODS OF SHOWERS AND SCATTERED STORMS. FORECAST
SOUNDINGS INDICATE LAYERS OF DRY AIR UPSTAIRS DURING THE DAY... SUCH
THAT WE SHOULD SEE SOME BREAKS IN THE CLOUDS ESPECIALLY ACROSS THE
SOUTHERN AND EASTERN CWA. LOW LEVEL THICKNESSES WITH A LITTLE BIT OF
SUNSHINE SUPPORT HIGHS OF 87-92.
FOR SATURDAY NIGHT THROUGH SUNDAY NIGHT: IN SHORT... EXPECT
ON-AND-OFF SCATTERED TO NUMEROUS SHOWERS AND STORMS THROUGH THE
LATTER HALF OF THE WEEKEND... WITH PRECIPITABLE WATER REMAINING NEAR
150% OF NORMAL... BOUNDARY LAYER FLOW REMAINING CONFLUENT OUT OF THE
S AND SW KEEPING LOW LEVEL MOISTURE ELEVATED... AND THE MID LEVEL
TROUGH AXIS HOLDING TO OUR WEST. THE LIFTED CONDENSATION LEVEL
ACROSS THE AREA DROPS EARLY SATURDAY NIGHT AND REMAINS IN THE
900-970 MB RANGE THROUGH SUNDAY NIGHT. THIS YIELDS A DEEPENING
LCL-TO-FREEZING-LEVEL LAYER TO 3.5-3.8 KM WHICH FAVORS WARM RAIN
PROCESSES... AND SOME BANDS OF HEAVIER SHOWERS ARE POSSIBLE.
FORECAST SOUNDINGS SHOW MODERATE INSTABILITY PERSISTING... ALTHOUGH
THE DEEP LAYER SHEAR WILL BE MARGINAL AT AROUND 15-20 KTS... AND A
TIGHT LOW LEVEL JET APPEARS TO BE LACKING... SO THE POTENTIAL FOR
STRONG STORMS STILL LOOKS LIMITED BUT THIS WILL NEED TO BE WATCHED.
FURTHER COMPLICATING MATTERS STARTING SUNDAY IS THE DIVERGENT
SOLUTIONS OF THE NAM AND GFS... WITH THE FORMER CLOSING OFF A MID
LEVEL LOW NEAR MEMPHIS BY LATE SUNDAY WHILE THE LATTER HAS THE WEAK
TROUGH SLOWLY LIFTING OUT TO OUR NW. WHILE THE GFS IS INDEED
TRENDING SLOWLY WITH THE EJECTION OF THIS TROUGH... WHICH IS
REASONABLE CONSIDERING THE NORTHWARD RETREAT OF THE WESTERLIES...
THE NAM LOOKS TOO OVERDONE TOO FAR SOUTH. EITHER WAY... NC REMAINS
ON THE WET SIDE OF THIS TROUGH. HIGHS SUNDAY SHOULD BE JUST UNDER
CLIMATOLOGY WITH ABUNDANT CLOUD COVER. LOWS A CATEGORY ABOVE NORMAL
BOTH NIGHTS. -GIH
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 340 AM FRIDAY...
FOR MONDAY: IF THE GFS/ECMWF SOLUTION OF THE SLOW-MOVING YET
PROGRESSIVE TROUGH AXIS SHIFTING THROUGH THE CENTRAL APPALACHIANS
AND NW NC INTO THE NORTHEAST STATES LATE SUNDAY NIGHT THROUGH MONDAY
ENDS UP CORRECT... WE`RE STILL LIKELY TO SEE SCATTERED TO NUMEROUS
SHOWERS AND STORMS THROUGH MONDAY MORNING. THE GFS SHOWS CONTINUED
MODERATE INSTABILITY AND NORMALIZED CAPE (CAPE FROM LCL TO THE
EQUILIBRIUM LEVEL) EXCEEDS 0.2... FAVORING STRONG UPDRAFTS. WITH
DEEP LAYER SHEAR NEARING 30 KTS AS THE TROUGH AXIS SWEEPS BY TO OUR
NW AND WITH THE MID LEVELS DRYING OUT SOMEWHAT IN THE AFTERNOON...
WE COULD SEE A RISK OF A FEW STRONG STORMS IF THE EXPECTED MORNING
PRECIP AND CLOUDS DON`T HINDER AFTERNOON DESTABILIZATION. HIGHS
SHOULD BE NEAR NORMAL... IN THE UPPER 80S TO NEAR 90.
FOR THE REMAINDER OF THE PERIOD: THE BERMUDA RIDGE ATTEMPTS TO
RETROGRADE BACK TOWARD THE SOUTHEAST COAST AND FL THROUGH MID
WEEK... WHILE SHORTWAVE ENERGY MOVING ACROSS THE US/CANADA BORDER
ALLOWS THE WESTERLIES TO DIP A BIT SOUTHWARD INTO THE NRN GREAT
LAKES/ST LAWRENCE VALLEY/NORTHEAST. VERY LITTLE CHANGES AT THE
SURFACE... WITH THE ATLANTIC-CENTERED SURFACE HIGH HOLDING IN PLACE
AND EXTENDING WSW INTO THE SOUTHEAST COASTAL SECTIONS... WITH A
PERSISTENT PIEDMONT TROUGH OVER CENTRAL/WRN NC AND PRECIPITABLE
WATER REMAINING IN THE 120-140% OF NORMAL RANGE. INASMUCH AS I WOULD
LIKE TO BE ABLE TO DISCERN ONE DAY AS BEING BETTER THAN ANOTHER FOR
SCATTERED MAINLY AFTERNOON/EVENING SHOWERS AND STORMS... AT THIS
RANGE AND WITH MODEL VARIATION IN THE DETAILS... IT REMAINS NEARLY
IMPOSSIBLE. WILL CONTINUE WITH CHANCE POPS... MAINLY AFTERNOON AND
EVENING... TUESDAY THROUGH THURSDAY. GFS/ECMWF THICKNESSES REMAIN
NEAR NORMAL AND TEMPERATURES SHOULD RUN CLOSE TO NORMAL THROUGH THE
PERIOD AS WELL. -GIH
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 2 PM FRIDAY...
IN GENERAL... VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD...WITH
THE EXCEPTION BEING THE POTENTIAL FOR ISOLATED TO SCATTERED
CONVECTION. FOR THE REST OF THE DAY THROUGH TONIGHT... BEST
POTENTIAL FOR CONVECTION WILL BE AT THE TRIAD TERMINALS. IN THIS
REGION...THE MID LEVEL CAP IS WEAKER AND LOW LEVEL CONVERGENCE
COMBINED WITH A WEAK UPPER LEVEL DISTURBANCE MOVING EAST FROM THE TN
VALLEY WILL SUPPORT THE DEVELOPMENT OF CONVECTION THROUGH LATE THIS
AFTERNOON AND INTO TONIGHT. RESULTANT OUTFLOW BOUNDARIES EMANATING
FROM CONVECTION OVER THE FOOTHILLS MAY ALSO BECOME A TRIGGER FOR
CONVECTIVE DEVELOPMENT. TOO MUCH UNCERTAINTY REMAINS REGARDING
COVERAGE AND TIMING OF CONVECTION...SO WILL INCLUDE A CB AT GSO/INT
AND AS FAR EAST AS RDU FOR THIS EVENING THROUGH LATE TONIGHT. ANY
CONVECTION ACROSS THE AREA SHOULD WANE DURING THE PREDAWN HOURS.
WINDS AT 2 KFT WILL INCREASE TO AROUND 25 KT OVERNIGHT. WHILE WE MAY
FALL SHORT OF EXACT LOW LEVEL WIND SHEAR CRITERIA...AT LEAST 15-20
KT OF LLWS WILL BE PRESENT AFTER MIDNIGHT WHICH COULD AFFECT SMALLER
AIRCRAFT AND GENERAL AVIATION INTERESTS.
AREAL EXTENT OF CONVECTION WILL INCREASE ON SATURDAY AS THERE WILL
BE NO MID LEVEL CAP AND DEEP LAYER MOISTURE AND INSTABILITY IS
PLENTIFUL. EXPECT SCATTERED TO NUMEROUS THUNDERSTORMS TO AFFECT
CENTRAL NC STARTING ROUGHLY AROUND 16Z TOMORROW AND THIS ACTIVITY
WILL LIKELY PERSIST INTO SATURDAY NIGHT. WILL INTRODUCE CB AT 16Z AT
ALL TERMINALS TO ACCOUNT FOR THE CONVECTIVE POTENTIAL. OTHERWISE...
VFR CONDITIONS EXPECTED OUTSIDE CONVECTION.
CHANCES FOR DIURNAL CONVECTION WILL PERSIST THROUGH AT LEAST TUESDAY
OF NEXT WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...JFB
SHORT TERM...HARTFIELD
LONG TERM...HARTFIELD
AVIATION...JFB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1005 AM EDT THU JUL 3 2008
.SYNOPSIS...
HIGH PRESSURE CENTERED OUT OVER THE ATLANTIC WILL CONTINUE TO EXTEND
WESTWARD INTO THE REGION THROUGH FRIDAY. MOISTURE WILL SLOWLY
INCREASE OVER THE AREA FRIDAY THROUGH FRIDAY NIGHT... LEADING TO AN
INCREASING CHANCE OF SHOWERS AND STORMS OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 10 AM THURSDAY... ANOTHER QUITE DAY IS ON TAP FOR CENTRAL
NORTH CAROLINA. WITH NO FOCUS FOR CONVECTION AND THE MID LEVEL
INVERSION CAPPING THE ATMOSPHERE... CONDITIONS WILL REMAIN DRY
ACROSS THE CWA. THE PREVIOUS FORECAST LOOKS TO BE IN EXCELLENT SHAPE.
THUS... PLAN ONLY TO TWEAK HOURLY TEMP AND DEWPOINT TEMPS TODAY...
AS LOW TEMPS THIS MORNING WERE A BIT WARMER THAN EXPECTED AS WINDS
STAYED UP A BIT MORE THAN EXPECTED OVERNIGHT.
FOR TODAY... EXPECT ONLY A SCATTERING OF FLAT CUMULUS AND HIGH
LEVEL DEBRIS CLOUDINESS FROM CONVECTION OVER THE MIDWEST TRANSLATING
SOUTH AND EAST INTO OUR AREA. HOWEVER... THE THIN HIGH CLOUDS SHOULD
NOT PREVENT US FROM REACHING FULL SUN HIGHS TODAY. HAVE OPTED ONCE
AGAIN TO USE THE LOCAL DRY ADIABATIC HIGH TEMPERATURE SCHEME...
WHICH YIELDS HIGHS AROUND 90 IN THE NORTHWEST TO LOWER 90S ELSEWHERE
ACROSS CENTRAL NC. THIS IS A FEW DEGREES AT MOST LOCATIONS BELOW MAV
GUIDANCE... AS MAV GUIDANCE HAS BEEN RUNNING A BIT WARM FOR HIGH
OVER THE LAST SEVERAL DAYS. -BSD
FOR TONIGHT: LIGHT SOUTHERLY TO SOUTHWESTERLY BOUNDARY LAYER FLOW
WILL HOLD THROUGH THE NIGHT AHEAD OF THE COLD FRONT THAT IS SLOWLY
APPROACHING FROM THE NORTHWEST. FORECAST SOUNDINGS THROUGH THE
OVERNIGHT HOURS SHOW A LINGERING LAYER OF NEAR SATURATION JUST
BENEATH THE SUBSIDENCE INVERSION ALOFT... AND USING NAM TRAJECTORIES
WE CAN TRACE THIS BACK TO HIGHER MOISTURE IN THE 2-3 KM LAYER
UPSTREAM OVER SRN GA... DEPICTED WELL ON THE 00Z/03 TLH SOUNDING.
THESE CLOUDS SHOULD BE MOSTLY SCATTERED... BUT WITH THE MODELS
SHOWING A COL AREA NEARBY AT 700 MB... THIS MOISTURE MAY POOL ENOUGH
TO PRODUCE PATCHES OF BROKEN CLOUDS OVERNIGHT... ESPECIALLY OVER THE
SOUTHERN COUNTIES OF CENTRAL NC. OTHERWISE... HIGH CLOUDINESS
PRODUCED BY THE PREFRONTAL MCS ACTIVITY SHOULD THICKEN OVER NC
DURING THE NIGHT. AS A RESULT THE LOWS SHOULD BE NOTICEABLY MILDER
THAN PREVIOUS NIGHTS... IN THE 65-70 RANGE. -GIH
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 315 AM THURSDAY...
FOR JULY FOURTH: THE LATEST MODEL OUTPUT INDICATES THE FRONT WILL
HANG UP ACROSS CENTRAL VA TO THE KY/TN BORDER... WITH A LIKELY LOW
PRESSURE AREA RIDING ALONG THE FRONT... AND THE WEAK LEE SURFACE
TROUGH IN PLACE THROUGH NC. AFTERNOON SURFACE DEW POINTS WILL BE
INCREASING INTO THE LOWER-MID 60S... HOWEVER THERE WILL STILL BE
PLENTY OF DRY AIR IN THE SUBCLOUD LAYER AS WELL AS IN THE MID
LEVELS... AND WITH A LINGERING (ALBEIT WEAKER) CAP ALOFT... IT MAY
BE DIFFICULT TO GET ENOUGH BUOYANCY FOR THUNDERSTORM DEVELOPMENT.
INDEED... SREF PROBABILITIES OF CAPE GREATER THAN 1000 J/KG IS VERY
SMALL OVER ALL BUT THE NE BORDER COUNTIES ON FRIDAY. WITH THE MID
LEVEL TROUGH BEGINNING TO SHARPEN FROM MI THROUGH WRN KY/TN DURING
FRIDAY... ANY MCV RESULTING FROM MCS ACTIVITY IS LIKELY TO SKIRT
JUST TO OUR NORTH... ALONG WITH THE BETTER UPPER DIVERGENCE
ASSOCIATED WITH THE WEAK UPPER JET TO OUR NORTH. THE MEAN STEERING
FLOW FROM THE WSW ALSO DOES NOT FAVOR ANY HIGHER-TERRAIN CONVECTION
MOVING INTO THE TRIAD AREA. WILL HOLD POPS AT LESS THAN 15% FOR
NOW... BUT WOULD NOT BE SURPRISED TO SEE AN ISOLATED STORM WORK INTO
THE EXTREME NORTHERN CWA... FROM THE TRIAD EASTWARD THROUGH LAKE
GASTON... LATE FRIDAY AFTERNOON. THICKNESSES ARE PROJECTED TO RISE
TO AROUND 20 M ABOVE NORMAL... AND UPSTREAM HIGHS YESTERDAY WERE IN
THE 90-95 RANGE... REASONABLE FOR OUR AREA GIVEN THE DRY ADIABATIC
LOW LEVEL THERMAL PROFILE.
FOR FRIDAY NIGHT THROUGH SATURDAY NIGHT: PRECIPITABLE WATER FINALLY
JUMPS UP TO NEARLY 150% OF NORMAL FRIDAY NIGHT... AND WITH
INCREASING CYCLONIC MID LEVEL FLOW AS THE TROUGH AXIS ALOFT SHIFTS
SLOWLY EASTWARD AND INDICATIONS OF RISING LOW LEVEL MASS CONVERGENCE
OVER NC... WILL INCLUDE THE POSSIBILITY OF AN ISOLATED SHOWER FRIDAY
NIGHT. EXPECT LOWS OF 69-73... JUST ABOVE MOS GUIDANCE LOWS. THE 850
MB THETA-E RIDGE PERSIST FROM THE GULF STATES INTO NC THROUGH
SATURDAY NIGHT... AND INSTABILITY IS EXPECTED TO INCREASE
MARKEDLY... ESPECIALLY SATURDAY AFTERNOON WHEN THE SREF
PROBABILITIES OF MODERATE CAPE EXCEED 65%. GFS FORECAST SOUNDINGS
SHOW SURFACE CAPE EXCEEDING 2000 J/KG OVER MUCH OF THE AREA... AND
BOTH THE NAM AND GFS SHOW INCREASING UPPER DIVERGENCE OVER CENTRAL
NC LATE SATURDAY INTO SATURDAY NIGHT. WILL RAISE POPS UP INTO THE
HIGH CHANCE RANGE... HIGHEST IN THE NORTHWEST. THE INCREASED CLOUD
COVER SHOULD TIGHTEN UP THE DIURNAL RANGE... AND HIGHS SATURDAY
SHOULD BE 85-91 FOLLOWED BY LOWS OF 69-73. -GIH
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 330 AM THURSDAY...
THE SURFACE FRONT TO OUR NORTH DISSIPATES SUNDAY WHILE THE MID LEVEL
TROUGH HOLDS JUST TO OUR WEST... AND MAY CLOSE OFF A LOW OVER THE
OHIO VALLEY. THE LATEST ECMWF/GFS SHOW CONSIDERABLE MOISTURE
ADVECTION AT ALL LEVELS INTO NC... ALTHOUGH THE GFS APPEARS OVERDONE
WITH ITS PRECIPITABLE WATER APPROACHING 2 INCHES. WILL HOLD ONTO
HIGH CHANCE POPS THROUGH SUNDAY GIVEN THE MOISTURE IN PLACE... THE
MID LEVEL CYCLONIC FLOW AND THE GLANCING BLOW OF SHORTWAVE ENERGY TO
OUR WEST AND NORTH. LITTLE CHANGE IS NEEDED TO EXISTING FORECAST
TEMPERATURES... WITH HIGHS IN THE MID TO UPPER 80S SUNDAY WITH
PLENTY OF CLOUDS.
THE CORE OF THE MID LEVEL TROUGH MOVES NORTHEASTWARD THROUGH NEW
ENGLAND SUNDAY NIGHT THROUGH MONDAY WITH A MODEST RISE IN HEIGHTS
OVER NC AS THE ATLANTIC RIDGE ATTEMPTS TO PUSH BACK WESTWARD INTO
NC. A SHORTWAVE TROUGH THAT SHIFTS ACROSS SOUTH CENTRAL CANADA
SUNDAY-MONDAY LEADS TO MORE MEAN TROUGHING FROM THE GREAT LAKES DOWN
INTO THE SOUTHERN PLAINS MONDAY INTO WEDNESDAY. WITH CONTINUED MOIST
LOW LEVEL FLOW AROUND THE OFFSHORE HIGH AND THE NEW COLD FRONT
HOLDING WELL TO OUR NORTHWEST... WILL NEED TO HOLD ONTO A RISK OF
TYPICAL LATE DAY SHOWERS AND STORMS... PERHAPS BETTER IN THE EAST
HALF... EAST OF THE PIEDMONT TROUGH. NEAR NORMAL HIGHS AND SLIGHTLY
ABOVE NORMAL LOWS STILL LOOK GOOD FOR MONDAY... AND A SLIGHTLY
INCREASE IN TEMPS THROUGH WEDNESDAY IS REASONABLE AND FOLLOWS THE
LOW LEVEL THICKNESS TREND. -GIH
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
AS OF 655 AM THURSDAY...
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD... AS DEEP LAYER
ATMOSPHERIC MOISTURE OVER NC IS EXCEPTIONALLY LOW FOR EARLY JULY...
AND FORECAST TO ONLY MARGINALLY INCREASE THROUGH TONIGHT. THE
DIVISION OF AIR QUALITY AND THE NWS RADAR DERIVED WIND PROFILE DATA
INDICATE THAT THE 30 KT LOW LEVEL JET THAT DEVELOPED OVER CENTRAL NC
LAST NIGHT HAS WEAKENED. THE POTENTIAL EXISTS FOR NOCTURNAL LOW
LEVEL JET DEVELOPMENT BETWEEN 1500 AND 2000 FT AGAIN TONIGHT AND
FRIDAY NIGHT... BUT LOW LEVEL WIND SHEAR CRITERIA IS NOT EXPECTED TO
BE MET. NONETHELESS... THE ASSOCIATED WIND SHEAR MAY PROVIDE FOR
A LITTLE TURBULENCE EACH NIGHT... ESPECIALLY FOR SMALLER AIRCRAFT.
LOOKING AHEAD... BRIEF MVFR CONDITIONS IN SHOWERS AND THUNDERSTORMS
ARE EXPECTED SATURDAY THROUGH MONDAY... AS AN UPPER LEVEL TROUGH
AMPLIFIES OVER THE OHIO VALLEY. -MWS
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...BSD/HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...HARTFIELD
AVIATION...MWS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
712 AM EDT THU JUL 3 2008
.SYNOPSIS...
HIGH PRESSURE CENTERED OUT OVER THE ATLANTIC WILL CONTINUE TO EXTEND
WESTWARD INTO THE REGION THROUGH FRIDAY. MOISTURE WILL SLOWLY
INCREASE OVER THE AREA FRIDAY THROUGH FRIDAY NIGHT... LEADING TO AN
INCREASING CHANCE OF SHOWERS AND STORMS OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 110 AM THURSDAY...
WE`LL SEE A CONTINUATION OF QUIET AND SEASONABLY DRY CONDITIONS
TODAY AS BERMUDA HIGH PRESSURE EXTENDS WESTWARD THROUGH THE
CAROLINAS. PRECIPITABLE WATER VALUES REMAIN AROUND 0.7 INCH
ACCORDING TO NOAA GPS MEASUREMENTS... WHICH IS JUST 60% OF NORMAL...
AND BOTH OBSERVED 00Z PROXIMITY SOUNDINGS AND FORECAST SOUNDINGS
SHOW A WARM MID LEVEL CAP... WHICH COMBINED WITH LOW SURFACE DEW
POINTS AND THE LACK OF ANY FORCING FEATURES WILL PUT THE KIBOSH ON
ANY CONVECTIVE POTENTIAL. WE SHOULD HOWEVER SEE SCATTERED FLAT
CUMULUS THIS AFTERNOON... PLUS UPPER LEVEL TRAJECTORIES SUGGEST THAT
BLOWOFF HIGH CLOUDINESS FROM WIDESPREAD MCS ACTIVITY UPSTREAM...
JUST AHEAD OF THE COLD FRONT FROM THE LOWER GREAT LAKES THROUGH THE
CENTRAL MISSISSIPPI VALLEY... WILL LEAD TO INCREASING HIGH CLOUDS
OVER NC LATER TODAY. THIS SHOULD HAVE MINIMAL IMPACT ON TEMPERATURES
THOUGH... WHICH ARE STILL EXPECTED TO PEAK NEAR 90 TO THE MID 90S...
VERY CLOSE TO OUTPUT FROM THE LOCAL DRY ADIABATIC HIGH TEMPERATURE
SCHEME... AND JUST UNDER MOS GUIDANCE HIGHS WHICH HAVE SHOWN A WARM
BIAS FOR THE LAST FEW DAYS. -GIH
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
AS OF 315 AM THURSDAY...
FOR TONIGHT: LIGHT SOUTHERLY TO SOUTHWESTERLY BOUNDARY LAYER FLOW
WILL HOLD THROUGH THE NIGHT AHEAD OF THE COLD FRONT THAT IS SLOWLY
APPROACHING FROM THE NORTHWEST. FORECAST SOUNDINGS THROUGH THE
OVERNIGHT HOURS SHOW A LINGERING LAYER OF NEAR SATURATION JUST
BENEATH THE SUBSIDENCE INVERSION ALOFT... AND USING NAM TRAJECTORIES
WE CAN TRACE THIS BACK TO HIGHER MOISTURE IN THE 2-3 KM LAYER
UPSTREAM OVER SRN GA... DEPICTED WELL ON THE 00Z/03 TLH SOUNDING.
THESE CLOUDS SHOULD BE MOSTLY SCATTERED... BUT WITH THE MODELS
SHOWING A COL AREA NEARBY AT 700 MB... THIS MOISTURE MAY POOL ENOUGH
TO PRODUCE PATCHES OF BROKEN CLOUDS OVERNIGHT... ESPECIALLY OVER THE
SOUTHERN COUNTIES OF CENTRAL NC. OTHERWISE... HIGH CLOUDINESS
PRODUCED BY THE PREFRONTAL MCS ACTIVITY SHOULD THICKEN OVER NC
DURING THE NIGHT. AS A RESULT THE LOWS SHOULD BE NOTICEABLY MILDER
THAN PREVIOUS NIGHTS... IN THE 65-70 RANGE.
FOR JULY FOURTH: THE LATEST MODEL OUTPUT INDICATES THE FRONT WILL
HANG UP ACROSS CENTRAL VA TO THE KY/TN BORDER... WITH A LIKELY LOW
PRESSURE AREA RIDING ALONG THE FRONT... AND THE WEAK LEE SURFACE
TROUGH IN PLACE THROUGH NC. AFTERNOON SURFACE DEW POINTS WILL BE
INCREASING INTO THE LOWER-MID 60S... HOWEVER THERE WILL STILL BE
PLENTY OF DRY AIR IN THE SUBCLOUD LAYER AS WELL AS IN THE MID
LEVELS... AND WITH A LINGERING (ALBEIT WEAKER) CAP ALOFT... IT MAY
BE DIFFICULT TO GET ENOUGH BUOYANCY FOR THUNDERSTORM DEVELOPMENT.
INDEED... SREF PROBABILITIES OF CAPE GREATER THAN 1000 J/KG IS VERY
SMALL OVER ALL BUT THE NE BORDER COUNTIES ON FRIDAY. WITH THE MID
LEVEL TROUGH BEGINNING TO SHARPEN FROM MI THROUGH WRN KY/TN DURING
FRIDAY... ANY MCV RESULTING FROM MCS ACTIVITY IS LIKELY TO SKIRT
JUST TO OUR NORTH... ALONG WITH THE BETTER UPPER DIVERGENCE
ASSOCIATED WITH THE WEAK UPPER JET TO OUR NORTH. THE MEAN STEERING
FLOW FROM THE WSW ALSO DOES NOT FAVOR ANY HIGHER-TERRAIN CONVECTION
MOVING INTO THE TRIAD AREA. WILL HOLD POPS AT LESS THAN 15% FOR
NOW... BUT WOULD NOT BE SURPRISED TO SEE AN ISOLATED STORM WORK INTO
THE EXTREME NORTHERN CWA... FROM THE TRIAD EASTWARD THROUGH LAKE
GASTON... LATE FRIDAY AFTERNOON. THICKNESSES ARE PROJECTED TO RISE
TO AROUND 20 M ABOVE NORMAL... AND UPSTREAM HIGHS YESTERDAY WERE IN
THE 90-95 RANGE... REASONABLE FOR OUR AREA GIVEN THE DRY ADIABATIC
LOW LEVEL THERMAL PROFILE.
FOR FRIDAY NIGHT THROUGH SATURDAY NIGHT: PRECIPITABLE WATER FINALLY
JUMPS UP TO NEARLY 150% OF NORMAL FRIDAY NIGHT... AND WITH
INCREASING CYCLONIC MID LEVEL FLOW AS THE TROUGH AXIS ALOFT SHIFTS
SLOWLY EASTWARD AND INDICATIONS OF RISING LOW LEVEL MASS CONVERGENCE
OVER NC... WILL INCLUDE THE POSSIBILITY OF AN ISOLATED SHOWER FRIDAY
NIGHT. EXPECT LOWS OF 69-73... JUST ABOVE MOS GUIDANCE LOWS. THE 850
MB THETA-E RIDGE PERSIST FROM THE GULF STATES INTO NC THROUGH
SATURDAY NIGHT... AND INSTABILITY IS EXPECTED TO INCREASE
MARKEDLY... ESPECIALLY SATURDAY AFTERNOON WHEN THE SREF
PROBABILITIES OF MODERATE CAPE EXCEED 65%. GFS FORECAST SOUNDINGS
SHOW SURFACE CAPE EXCEEDING 2000 J/KG OVER MUCH OF THE AREA... AND
BOTH THE NAM AND GFS SHOW INCREASING UPPER DIVERGENCE OVER CENTRAL
NC LATE SATURDAY INTO SATURDAY NIGHT. WILL RAISE POPS UP INTO THE
HIGH CHANCE RANGE... HIGHEST IN THE NORTHWEST. THE INCREASED CLOUD
COVER SHOULD TIGHTEN UP THE DIURNAL RANGE... AND HIGHS SATURDAY
SHOULD BE 85-91 FOLLOWED BY LOWS OF 69-73. -GIH
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 330 AM THURSDAY...
THE SURFACE FRONT TO OUR NORTH DISSIPATES SUNDAY WHILE THE MID LEVEL
TROUGH HOLDS JUST TO OUR WEST... AND MAY CLOSE OFF A LOW OVER THE
OHIO VALLEY. THE LATEST ECMWF/GFS SHOW CONSIDERABLE MOISTURE
ADVECTION AT ALL LEVELS INTO NC... ALTHOUGH THE GFS APPEARS OVERDONE
WITH ITS PRECIPITABLE WATER APPROACHING 2 INCHES. WILL HOLD ONTO
HIGH CHANCE POPS THROUGH SUNDAY GIVEN THE MOISTURE IN PLACE... THE
MID LEVEL CYCLONIC FLOW AND THE GLANCING BLOW OF SHORTWAVE ENERGY TO
OUR WEST AND NORTH. LITTLE CHANGE IS NEEDED TO EXISTING FORECAST
TEMPERATURES... WITH HIGHS IN THE MID TO UPPER 80S SUNDAY WITH
PLENTY OF CLOUDS.
THE CORE OF THE MID LEVEL TROUGH MOVES NORTHEASTWARD THROUGH NEW
ENGLAND SUNDAY NIGHT THROUGH MONDAY WITH A MODEST RISE IN HEIGHTS
OVER NC AS THE ATLANTIC RIDGE ATTEMPTS TO PUSH BACK WESTWARD INTO
NC. A SHORTWAVE TROUGH THAT SHIFTS ACROSS SOUTH CENTRAL CANADA
SUNDAY-MONDAY LEADS TO MORE MEAN TROUGHING FROM THE GREAT LAKES DOWN
INTO THE SOUTHERN PLAINS MONDAY INTO WEDNESDAY. WITH CONTINUED MOIST
LOW LEVEL FLOW AROUND THE OFFSHORE HIGH AND THE NEW COLD FRONT
HOLDING WELL TO OUR NORTHWEST... WILL NEED TO HOLD ONTO A RISK OF
TYPICAL LATE DAY SHOWERS AND STORMS... PERHAPS BETTER IN THE EAST
HALF... EAST OF THE PIEDMONT TROUGH. NEAR NORMAL HIGHS AND SLIGHTLY
ABOVE NORMAL LOWS STILL LOOK GOOD FOR MONDAY... AND A SLIGHTLY
INCREASE IN TEMPS THROUGH WEDNESDAY IS REASONABLE AND FOLLOWS THE
LOW LEVEL THICKNESS TREND. -GIH
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 655 AM THURSDAY...
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD... AS DEEP LAYER
ATMOSPHERIC MOISTURE OVER NC IS EXCEPTIONALLY LOW FOR EARLY JULY...
AND FORECAST TO ONLY MARGINALLY INCREASE THROUGH TONIGHT. THE
DIVISION OF AIR QUALITY AND THE NWS RADAR DERIVED WIND PROFILE DATA
INDICATE THAT THE 30 KT LOW LEVEL JET THAT DEVELOPED OVER CENTRAL NC
LAST NIGHT HAS WEAKENED. THE POTENTIAL EXISTS FOR NOCTURNAL LOW
LEVEL JET DEVELOPMENT BETWEEN 1500 AND 2000 FT AGAIN TONIGHT AND
FRIDAY NIGHT... BUT LOW LEVEL WIND SHEAR CRITERIA IS NOT EXPECTED TO
BE MET. NONETHELESS... THE ASSOCIATED WIND SHEAR MAY PROVIDE FOR
A LITTLE TURBULENCE EACH NIGHT... ESPECIALLY FOR SMALLER AIRCRAFT.
LOOKING AHEAD... BRIEF MVFR CONDITIONS IN SHOWERS AND THUNDERSTORMS
ARE EXPECTED SATURDAY THROUGH MONDAY... AS AN UPPER LEVEL TROUGH
AMPLIFIES OVER THE OHIO VALLEY. -MWS
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...HARTFIELD
AVIATION...MWS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
335 AM EDT THU JUL 3 2008
.SYNOPSIS...
HIGH PRESSURE CENTERED OUT OVER THE ATLANTIC WILL CONTINUE TO EXTEND
WESTWARD INTO THE REGION THROUGH FRIDAY. MOISTURE WILL SLOWLY
INCREASE OVER THE AREA FRIDAY THROUGH FRIDAY NIGHT... LEADING TO AN
INCREASING CHANCE OF SHOWERS AND STORMS OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 110 AM THURSDAY...
WE`LL SEE A CONTINUATION OF QUIET AND SEASONABLY DRY CONDITIONS
TODAY AS BERMUDA HIGH PRESSURE EXTENDS WESTWARD THROUGH THE
CAROLINAS. PRECIPITABLE WATER VALUES REMAIN AROUND 0.7 INCH
ACCORDING TO NOAA GPS MEASUREMENTS... WHICH IS JUST 60% OF NORMAL...
AND BOTH OBSERVED 00Z PROXIMITY SOUNDINGS AND FORECAST SOUNDINGS
SHOW A WARM MID LEVEL CAP... WHICH COMBINED WITH LOW SURFACE DEW
POINTS AND THE LACK OF ANY FORCING FEATURES WILL PUT THE KIBOSH ON
ANY CONVECTIVE POTENTIAL. WE SHOULD HOWEVER SEE SCATTERED FLAT
CUMULUS THIS AFTERNOON... PLUS UPPER LEVEL TRAJECTORIES SUGGEST THAT
BLOWOFF HIGH CLOUDINESS FROM WIDESPREAD MCS ACTIVITY UPSTREAM...
JUST AHEAD OF THE COLD FRONT FROM THE LOWER GREAT LAKES THROUGH THE
CENTRAL MISSISSIPPI VALLEY... WILL LEAD TO INCREASING HIGH CLOUDS
OVER NC LATER TODAY. THIS SHOULD HAVE MINIMAL IMPACT ON TEMPERATURES
THOUGH... WHICH ARE STILL EXPECTED TO PEAK NEAR 90 TO THE MID 90S...
VERY CLOSE TO OUTPUT FROM THE LOCAL DRY ADIABATIC HIGH TEMPERATURE
SCHEME... AND JUST UNDER MOS GUIDANCE HIGHS WHICH HAVE SHOWN A WARM
BIAS FOR THE LAST FEW DAYS. -GIH
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
AS OF 315 AM THURSDAY...
FOR TONIGHT: LIGHT SOUTHERLY TO SOUTHWESTERLY BOUNDARY LAYER FLOW
WILL HOLD THROUGH THE NIGHT AHEAD OF THE COLD FRONT THAT IS SLOWLY
APPROACHING FROM THE NORTHWEST. FORECAST SOUNDINGS THROUGH THE
OVERNIGHT HOURS SHOW A LINGERING LAYER OF NEAR SATURATION JUST
BENEATH THE SUBSIDENCE INVERSION ALOFT... AND USING NAM TRAJECTORIES
WE CAN TRACE THIS BACK TO HIGHER MOISTURE IN THE 2-3 KM LAYER
UPSTREAM OVER SRN GA... DEPICTED WELL ON THE 00Z/03 TLH SOUNDING.
THESE CLOUDS SHOULD BE MOSTLY SCATTERED... BUT WITH THE MODELS
SHOWING A COL AREA NEARBY AT 700 MB... THIS MOISTURE MAY POOL ENOUGH
TO PRODUCE PATCHES OF BROKEN CLOUDS OVERNIGHT... ESPECIALLY OVER THE
SOUTHERN COUNTIES OF CENTRAL NC. OTHERWISE... HIGH CLOUDINESS
PRODUCED BY THE PREFRONTAL MCS ACTIVITY SHOULD THICKEN OVER NC
DURING THE NIGHT. AS A RESULT THE LOWS SHOULD BE NOTICEABLY MILDER
THAN PREVIOUS NIGHTS... IN THE 65-70 RANGE.
FOR JULY FOURTH: THE LATEST MODEL OUTPUT INDICATES THE FRONT WILL
HANG UP ACROSS CENTRAL VA TO THE KY/TN BORDER... WITH A LIKELY LOW
PRESSURE AREA RIDING ALONG THE FRONT... AND THE WEAK LEE SURFACE
TROUGH IN PLACE THROUGH NC. AFTERNOON SURFACE DEW POINTS WILL BE
INCREASING INTO THE LOWER-MID 60S... HOWEVER THERE WILL STILL BE
PLENTY OF DRY AIR IN THE SUBCLOUD LAYER AS WELL AS IN THE MID
LEVELS... AND WITH A LINGERING (ALBEIT WEAKER) CAP ALOFT... IT MAY
BE DIFFICULT TO GET ENOUGH BUOYANCY FOR THUNDERSTORM DEVELOPMENT.
INDEED... SREF PROBABILITIES OF CAPE GREATER THAN 1000 J/KG IS VERY
SMALL OVER ALL BUT THE NE BORDER COUNTIES ON FRIDAY. WITH THE MID
LEVEL TROUGH BEGINNING TO SHARPEN FROM MI THROUGH WRN KY/TN DURING
FRIDAY... ANY MCV RESULTING FROM MCS ACTIVITY IS LIKELY TO SKIRT
JUST TO OUR NORTH... ALONG WITH THE BETTER UPPER DIVERGENCE
ASSOCIATED WITH THE WEAK UPPER JET TO OUR NORTH. THE MEAN STEERING
FLOW FROM THE WSW ALSO DOES NOT FAVOR ANY HIGHER-TERRAIN CONVECTION
MOVING INTO THE TRIAD AREA. WILL HOLD POPS AT LESS THAN 15% FOR
NOW... BUT WOULD NOT BE SURPRISED TO SEE AN ISOLATED STORM WORK INTO
THE EXTREME NORTHERN CWA... FROM THE TRIAD EASTWARD THROUGH LAKE
GASTON... LATE FRIDAY AFTERNOON. THICKNESSES ARE PROJECTED TO RISE
TO AROUND 20 M ABOVE NORMAL... AND UPSTREAM HIGHS YESTERDAY WERE IN
THE 90-95 RANGE... REASONABLE FOR OUR AREA GIVEN THE DRY ADIABATIC
LOW LEVEL THERMAL PROFILE.
FOR FRIDAY NIGHT THROUGH SATURDAY NIGHT: PRECIPITABLE WATER FINALLY
JUMPS UP TO NEARLY 150% OF NORMAL FRIDAY NIGHT... AND WITH
INCREASING CYCLONIC MID LEVEL FLOW AS THE TROUGH AXIS ALOFT SHIFTS
SLOWLY EASTWARD AND INDICATIONS OF RISING LOW LEVEL MASS CONVERGENCE
OVER NC... WILL INCLUDE THE POSSIBILITY OF AN ISOLATED SHOWER FRIDAY
NIGHT. EXPECT LOWS OF 69-73... JUST ABOVE MOS GUIDANCE LOWS. THE 850
MB THETA-E RIDGE PERSIST FROM THE GULF STATES INTO NC THROUGH
SATURDAY NIGHT... AND INSTABILITY IS EXPECTED TO INCREASE
MARKEDLY... ESPECIALLY SATURDAY AFTERNOON WHEN THE SREF
PROBABILITIES OF MODERATE CAPE EXCEED 65%. GFS FORECAST SOUNDINGS
SHOW SURFACE CAPE EXCEEDING 2000 J/KG OVER MUCH OF THE AREA... AND
BOTH THE NAM AND GFS SHOW INCREASING UPPER DIVERGENCE OVER CENTRAL
NC LATE SATURDAY INTO SATURDAY NIGHT. WILL RAISE POPS UP INTO THE
HIGH CHANCE RANGE... HIGHEST IN THE NORTHWEST. THE INCREASED CLOUD
COVER SHOULD TIGHTEN UP THE DIURNAL RANGE... AND HIGHS SATURDAY
SHOULD BE 85-91 FOLLOWED BY LOWS OF 69-73. -GIH
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 330 AM THURSDAY...
THE SURFACE FRONT TO OUR NORTH DISSIPATES SUNDAY WHILE THE MID LEVEL
TROUGH HOLDS JUST TO OUR WEST... AND MAY CLOSE OFF A LOW OVER THE
OHIO VALLEY. THE LATEST ECMWF/GFS SHOW CONSIDERABLE MOISTURE
ADVECTION AT ALL LEVELS INTO NC... ALTHOUGH THE GFS APPEARS OVERDONE
WITH ITS PRECIPITABLE WATER APPROACHING 2 INCHES. WILL HOLD ONTO
HIGH CHANCE POPS THROUGH SUNDAY GIVEN THE MOISTURE IN PLACE... THE
MID LEVEL CYCLONIC FLOW AND THE GLANCING BLOW OF SHORTWAVE ENERGY TO
OUR WEST AND NORTH. LITTLE CHANGE IS NEEDED TO EXISTING FORECAST
TEMPERATURES... WITH HIGHS IN THE MID TO UPPER 80S SUNDAY WITH
PLENTY OF CLOUDS.
THE CORE OF THE MID LEVEL TROUGH MOVES NORTHEASTWARD THROUGH NEW
ENGLAND SUNDAY NIGHT THROUGH MONDAY WITH A MODEST RISE IN HEIGHTS
OVER NC AS THE ATLANTIC RIDGE ATTEMPTS TO PUSH BACK WESTWARD INTO
NC. A SHORTWAVE TROUGH THAT SHIFTS ACROSS SOUTH CENTRAL CANADA
SUNDAY-MONDAY LEADS TO MORE MEAN TROUGHING FROM THE GREAT LAKES DOWN
INTO THE SOUTHERN PLAINS MONDAY INTO WEDNESDAY. WITH CONTINUED MOIST
LOW LEVEL FLOW AROUND THE OFFSHORE HIGH AND THE NEW COLD FRONT
HOLDING WELL TO OUR NORTHWEST... WILL NEED TO HOLD ONTO A RISK OF
TYPICAL LATE DAY SHOWERS AND STORMS... PERHAPS BETTER IN THE EAST
HALF... EAST OF THE PIEDMONT TROUGH. NEAR NORMAL HIGHS AND SLIGHTLY
ABOVE NORMAL LOWS STILL LOOK GOOD FOR MONDAY... AND A SLIGHTLY
INCREASE IN TEMPS THROUGH WEDNESDAY IS REASONABLE AND FOLLOWS THE
LOW LEVEL THICKNESS TREND. -GIH
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 145 AM THURSDAY...
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD... AS DEEP LAYER
ATMOSPHERIC MOISTURE IS EXCEPTIONALLY LOW FOR EARLY JULY... AND
FORECAST TO ONLY MARGINALLY INCREASE ON THURSDAY. OF MORE CONCERN...
WILL BE THE DEVELOPMENT OF A NOCTURNAL LOW LEVEL JET BETWEEN 1500
AND 2000 FT THIS MORNING AND AGAIN THURSDAY AND FRIDAY NIGHTS. IN
FACT... BOTH THE DIVISION OF AIR QUALITY AND THE NWS RADAR DERIVED
WIND PROFILE DATA INDICATE THAT A 220 DEGREE... 30 KT LLJ HAS
DEVELOPED OVER CENTRAL NC THIS MORNING. WHILE THE LLJ IS NOT
EXPECTED TO STRENGTHEN BEYOND ITS CURRENT SUB-CRITERIA 30 KT
STRENGTH... THE ASSOCIATED WIND SHEAR MAY PROVIDE FOR A LITTLE
TURBULENCE... NONETHELESS... ESPECIALLY FOR SMALLER AIRCRAFT. -MWS
VFR CONDITIONS THROUGH THE BALANCE OF THE WORK WEEK. UNSETTLED
WEATHER FOR THE HOLIDAY WEEKEND AS SOUTHERLY FLOW STRENGTHENS OVER
THE REGION...WITH THE APPROACH OF THE UPPER TROUGH FROM THE NW.
THIS WILL BRING THE CHANCE OF WIDESPREAD SHOWERS AND THUNDER...LATE
SATURDAY THROUGH MONDAY...POSSIBLY RESULTING IN A PERIOD OF MVFR
CONDITIONS IN HEAVIER PRECIPITATION. -CBL
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...HARTFIELD
AVIATION...MWS/CBL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
315 AM EDT THU JUL 3 2008
.SYNOPSIS...
HIGH PRESSURE CENTERED OUT OVER THE ATLANTIC WILL CONTINUE TO EXTEND
WESTWARD INTO THE REGION THROUGH FRIDAY. MOISTURE WILL SLOWLY
INCREASE OVER THE AREA FRIDAY THROUGH FRIDAY NIGHT... LEADING TO AN
INCREASING CHANCE OF SHOWERS AND STORMS OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 110 AM THURSDAY...
WE`LL SEE A CONTINUATION OF QUIET AND SEASONABLY DRY CONDITIONS
TODAY AS BERMUDA HIGH PRESSURE EXTENDS WESTWARD THROUGH THE
CAROLINAS. PRECIPITABLE WATER VALUES REMAIN AROUND 0.7 INCH
ACCORDING TO NOAA GPS MEASUREMENTS... WHICH IS JUST 60% OF NORMAL...
AND BOTH OBSERVED 00Z PROXIMITY SOUNDINGS AND FORECAST SOUNDINGS
SHOW A WARM MID LEVEL CAP... WHICH COMBINED WITH LOW SURFACE DEW
POINTS AND THE LACK OF ANY FORCING FEATURES WILL PUT THE KIBOSH ON
ANY CONVECTIVE POTENTIAL. WE SHOULD HOWEVER SEE SCATTERED FLAT
CUMULUS THIS AFTERNOON... PLUS UPPER LEVEL TRAJECTORIES SUGGEST THAT
BLOWOFF HIGH CLOUDINESS FROM WIDESPREAD MCS ACTIVITY UPSTREAM...
JUST AHEAD OF THE COLD FRONT FROM THE LOWER GREAT LAKES THROUGH THE
CENTRAL MISSISSIPPI VALLEY... WILL LEAD TO INCREASING HIGH CLOUDS
OVER NC LATER TODAY. THIS SHOULD HAVE MINIMAL IMPACT ON TEMPERATURES
THOUGH... WHICH ARE STILL EXPECTED TO PEAK NEAR 90 TO THE MID 90S...
VERY CLOSE TO OUTPUT FROM THE LOCAL DRY ADIABATIC HIGH TEMPERATURE
SCHEME... AND JUST UNDER MOS GUIDANCE HIGHS WHICH HAVE SHOWN A WARM
BIAS FOR THE LAST FEW DAYS. -GIH
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
AS OF 315 AM THURSDAY...
FOR TONIGHT: LIGHT SOUTHERLY TO SOUTHWESTERLY BOUNDARY LAYER FLOW
WILL HOLD THROUGH THE NIGHT AHEAD OF THE COLD FRONT THAT IS SLOWLY
APPROACHING FROM THE NORTHWEST. FORECAST SOUNDINGS THROUGH THE
OVERNIGHT HOURS SHOW A LINGERING LAYER OF NEAR SATURATION JUST
BENEATH THE SUBSIDENCE INVERSION ALOFT... AND USING NAM TRAJECTORIES
WE CAN TRACE THIS BACK TO HIGHER MOISTURE IN THE 2-3 KM LAYER
UPSTREAM OVER SRN GA... DEPICTED WELL ON THE 00Z/03 TLH SOUNDING.
THESE CLOUDS SHOULD BE MOSTLY SCATTERED... BUT WITH THE MODELS
SHOWING A COL AREA NEARBY AT 700 MB... THIS MOISTURE MAY POOL ENOUGH
TO PRODUCE PATCHES OF BROKEN CLOUDS OVERNIGHT... ESPECIALLY OVER THE
SOUTHERN COUNTIES OF CENTRAL NC. OTHERWISE... HIGH CLOUDINESS
PRODUCED BY THE PREFRONTAL MCS ACTIVITY SHOULD THICKEN OVER NC
DURING THE NIGHT. AS A RESULT THE LOWS SHOULD BE NOTICEABLY MILDER
THAN PREVIOUS NIGHTS... IN THE 65-70 RANGE.
FOR JULY FOURTH: THE LATEST MODEL OUTPUT INDICATES THE FRONT WILL
HANG UP ACROSS CENTRAL VA TO THE KY/TN BORDER... WITH A LIKELY LOW
PRESSURE AREA RIDING ALONG THE FRONT... AND THE WEAK LEE SURFACE
TROUGH IN PLACE THROUGH NC. AFTERNOON SURFACE DEW POINTS WILL BE
INCREASING INTO THE LOWER-MID 60S... HOWEVER THERE WILL STILL BE
PLENTY OF DRY AIR IN THE SUBCLOUD LAYER AS WELL AS IN THE MID
LEVELS... AND WITH A LINGERING (ALBEIT WEAKER) CAP ALOFT... IT MAY
BE DIFFICULT TO GET ENOUGH BUOYANCY FOR THUNDERSTORM DEVELOPMENT.
INDEED... SREF PROBABILITIES OF CAPE GREATER THAN 1000 J/KG IS VERY
SMALL OVER ALL BUT THE NE BORDER COUNTIES ON FRIDAY. WITH THE MID
LEVEL TROUGH BEGINNING TO SHARPEN FROM MI THROUGH WRN KY/TN DURING
FRIDAY... ANY MCV RESULTING FROM MCS ACTIVITY IS LIKELY TO SKIRT
JUST TO OUR NORTH... ALONG WITH THE BETTER UPPER DIVERGENCE
ASSOCIATED WITH THE WEAK UPPER JET TO OUR NORTH. THE MEAN STEERING
FLOW FROM THE WSW ALSO DOES NOT FAVOR ANY HIGHER-TERRAIN CONVECTION
MOVING INTO THE TRIAD AREA. WILL HOLD POPS AT LESS THAN 15% FOR
NOW... BUT WOULD NOT BE SURPRISED TO SEE AN ISOLATED STORM WORK INTO
THE EXTREME NORTHERN CWA... FROM THE TRIAD EASTWARD THROUGH LAKE
GASTON... LATE FRIDAY AFTERNOON. THICKNESSES ARE PROJECTED TO RISE
TO AROUND 20 M ABOVE NORMAL... AND UPSTREAM HIGHS YESTERDAY WERE IN
THE 90-95 RANGE... REASONABLE FOR OUR AREA GIVEN THE DRY ADIABATIC
LOW LEVEL THERMAL PROFILE.
FOR FRIDAY NIGHT THROUGH SATURDAY NIGHT: PRECIPITABLE WATER FINALLY
JUMPS UP TO NEARLY 150% OF NORMAL FRIDAY NIGHT... AND WITH
INCREASING CYCLONIC MID LEVEL FLOW AS THE TROUGH AXIS ALOFT SHIFTS
SLOWLY EASTWARD AND INDICATIONS OF RISING LOW LEVEL MASS CONVERGENCE
OVER NC... WILL INCLUDE THE POSSIBILITY OF AN ISOLATED SHOWER FRIDAY
NIGHT. EXPECT LOWS OF 69-73... JUST ABOVE MOS GUIDANCE LOWS. THE 850
MB THETA-E RIDGE PERSIST FROM THE GULF STATES INTO NC THROUGH
SATURDAY NIGHT... AND INSTABILITY IS EXPECTED TO INCREASE
MARKEDLY... ESPECIALLY SATURDAY AFTERNOON WHEN THE SREF
PROBABILITIES OF MODERATE CAPE EXCEED 65%. GFS FORECAST SOUNDINGS
SHOW SURFACE CAPE EXCEEDING 2000 J/KG OVER MUCH OF THE AREA... AND
BOTH THE NAM AND GFS SHOW INCREASING UPPER DIVERGENCE OVER CENTRAL
NC LATE SATURDAY INTO SATURDAY NIGHT. WILL RAISE POPS UP INTO THE
HIGH CHANCE RANGE... HIGHEST IN THE NORTHWEST. THE INCREASED CLOUD
COVER SHOULD TIGHTEN UP THE DIURNAL RANGE... AND HIGHS SATURDAY
SHOULD BE 85-91 FOLLOWED BY LOWS OF 69-73. -GIH
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 200 PM WEDNESDAY...
MID LEVEL TROUGH WILL LIFT EAST NORTHEAST OUT OF THE LOWER OHIO
VALLEY SATURDAY NIGHT AND SUNDAY...BRINGING THE BEST CHANCE FOR
WIDESPREAD RAINS TO CENTRAL NORTH CAROLINA IN SEVERAL DAYS.
AS THE TROUGH FLATTENS AND LIFTS NORTH MONDAY. ENOUGH ATMOSPHERIC
MOISTURE WILL REMAIN TO CONTINUE RAIN CHANCES...WITH THE BETTER
CHANCES IN THE EAST.
BROAD TROUGH PERSISTS OVER THE EAST COAST INTO WEDNESDAY. TIMING OF
ANY SHORT WAVE ENERGY THROUGH THE BASE OF THIS TROUGH IS SUSPECT
AT BEST. IT SAFE AT THIS TIME TO KEEP AFTERNOON RAIN CHANCES ABOVE
NORMAL TUESDAY AND WEDNESDAY...KNOWING THAT SHORT WAVE ENERGY WILL
EVENTUALLY BE RESOLVED BY THE MODELS TO FAVOR ONE PERIOD OVER THE
OTHER.
LOW TEMPERATURES SHOULD BE MOSTLY IN THE 69 TO 74 DEGREE RANGE
WITH ATMOSPHERIC MOISTURE AND CLOUDS GENERALLY ABOVE NORMAL.
AFTERNOON HIGHS NOT FAR FROM NORMAL AT 88 TO 93.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 145 AM THURSDAY...
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD... AS DEEP LAYER
ATMOSPHERIC MOISTURE IS EXCEPTIONALLY LOW FOR EARLY JULY... AND
FORECAST TO ONLY MARGINALLY INCREASE ON THURSDAY. OF MORE CONCERN...
WILL BE THE DEVELOPMENT OF A NOCTURNAL LOW LEVEL JET BETWEEN 1500
AND 2000 FT THIS MORNING AND AGAIN THURSDAY AND FRIDAY NIGHTS. IN
FACT... BOTH THE DIVISION OF AIR QUALITY AND THE NWS RADAR DERIVED
WIND PROFILE DATA INDICATE THAT A 220 DEGREE... 30 KT LLJ HAS
DEVELOPED OVER CENTRAL NC THIS MORNING. WHILE THE LLJ IS NOT
EXPECTED TO STRENGTHEN BEYOND ITS CURRENT SUB-CRITERIA 30 KT
STRENGTH... THE ASSOCIATED WIND SHEAR MAY PROVIDE FOR A LITTLE
TURBULENCE... NONETHELESS... ESPECIALLY FOR SMALLER AIRCRAFT. -MWS
VFR CONDITIONS THROUGH THE BALANCE OF THE WORK WEEK. UNSETTLED
WEATHER FOR THE HOLIDAY WEEKEND AS SOUTHERLY FLOW STRENGTHENS OVER
THE REGION...WITH THE APPROACH OF THE UPPER TROUGH FROM THE NW.
THIS WILL BRING THE CHANCE OF WIDESPREAD SHOWERS AND THUNDER...LATE
SATURDAY THROUGH MONDAY...POSSIBLY RESULTING IN A PERIOD OF MVFR
CONDITIONS IN HEAVIER PRECIPITATION. -CBL
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...RLH
AVIATION...MWS/CBL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
155 AM EDT THU JUL 3 2008
.SYNOPSIS...
HIGH PRESSURE CENTERED OUT OVER THE ATLANTIC WILL CONTINUE TO EXTEND
WESTWARD INTO THE REGION THROUGH FRIDAY. MOISTURE WILL SLOWLY
INCREASE OVER THE AREA FRIDAY THROUGH FRIDAY NIGHT... LEADING TO AN
INCREASING CHANCE OF SHOWERS AND STORMS OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 110 AM THURSDAY...
WE`LL SEE A CONTINUATION OF QUIET AND SEASONABLY DRY CONDITIONS
TODAY AS BERMUDA HIGH PRESSURE EXTENDS WESTWARD THROUGH THE
CAROLINAS. PRECIPITABLE WATER VALUES REMAIN AROUND 0.7 INCH
ACCORDING TO NOAA GPS MEASUREMENTS... WHICH IS JUST 60% OF NORMAL...
AND BOTH OBSERVED 00Z PROXIMITY SOUNDINGS AND FORECAST SOUNDINGS
SHOW A WARM MID LEVEL CAP... WHICH COMBINED WITH LOW SURFACE DEW
POINTS AND THE LACK OF ANY FORCING FEATURES WILL PUT THE KIBOSH ON
ANY CONVECTIVE POTENTIAL. WE SHOULD HOWEVER SEE SCATTERED FLAT
CUMULUS THIS AFTERNOON... PLUS UPPER LEVEL TRAJECTORIES SUGGEST THAT
BLOWOFF HIGH CLOUDINESS FROM WIDESPREAD MCS ACTIVITY UPSTREAM...
JUST AHEAD OF THE COLD FRONT FROM THE LOWER GREAT LAKES THROUGH THE
CENTRAL MISSISSIPPI VALLEY... WILL LEAD TO INCREASING HIGH CLOUDS
OVER NC LATER TODAY. THIS SHOULD HAVE MINIMAL IMPACT ON TEMPERATURES
THOUGH... WHICH ARE STILL EXPECTED TO PEAK NEAR 90 TO THE MID 90S...
VERY CLOSE TO OUTPUT FROM THE LOCAL DRY ADIABATIC HIGH TEMPERATURE
SCHEME... AND JUST UNDER MOS GUIDANCE HIGHS WHICH HAVE SHOWN A WARM
BIAS FOR THE LAST FEW DAYS. -GIH
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
AS OF 245 PM WEDNESDAY...
THURSDAY NIGHT: LOW TEMPS THU NIGHT SHOULD BE NEAR NORMAL...IN THE
MID/UPPER 60S ACROSS MOST OF THE AREA.
FRIDAY AND FRIDAY NIGHT:
THE SFC FRONT IN THE OHIO VALLEY AND MIDWEST THU EVENING IS PROGGED
TO STALL ACROSS KENTUCKY AND WEST VIRGINIA BY FRIDAY MORNING...WITH
BROAD TROUGHING ALOFT OVER THE OHIO VALLEY AND MIDWEST. THE 12Z GFS
IS GENERATING A SFC LOW ALONG THE STALLED FRONT IN MISSOURI...MOVING
EAST INTO THE OHIO VALLEY BY FRIDAY EVENING...WHILE THE 12Z NAM ONLY
KEEPS WEAK TROUGHING ALONG THE FRONT. THE DIFFERENCE IS THE RESULT
OF WHAT APPEARS TO BE CONVECTIVE FEEDBACK BY THE GFS IN ASSOC/W
HEAVY PRECIP BEING GENERATED THU EVENING THROUGH FRIDAY MORNING OVER
NE/KS/MO. WILL TREND MORE TOWARDS THE 12Z NAM SOLUTION WHICH SEEMS
MUCH MORE REASONABLE. EITHER WAY...THERE DOES NOT APPEAR TO BE MUCH
IN THE WAY OF LIFT ACROSS CENTRAL NC ON FRIDAY...OTHER THAN
WEAK/SHALLOW CONVERGENCE ASSOC/W SFC TROUGHING. ALTHOUGH THE AIRMASS
IS PROGGED TO MOISTEN ACROSS CENTRAL NC DURING THE DAY FRIDAY...FCST
SOUNDINGS STILL SHOW ABNORMALLY DRY LOW LEVELS (FOR EARLY JULY) AND
A MID-LEVEL SUBSIDENCE INVERSION. DUE TO THE MARGINAL OR ABSENT
THERMODYNAMICS AND LIFT NECESSARY FOR CONVECTION TO DEVELOP...WILL
CONTINUE A DRY FORECAST ON FRIDAY. ANY CONVECTION THAT DEVELOPS
SHOULD REMAIN ALONG/WEST OF THE MOUNTAIN RIDGES OVER THE OH/TN
VALLEYS IN VICINITY OF THE STALLED FRONT WHERE BETTER MOISTURE IS
LOCATED AND WHERE THERE IS BROAD TROUGHING ALOFT. HIGH TEMPS ON
FRIDAY ARE EXPECTED TO BE SIMILAR TO THURSDAY...RANGING FROM
90-95F...WITH PARTLY CLOUDY SKIES ASSOC/W MORE DIURNAL CU AND
PERHAPS SOME MID/UPPER LEVEL CONVECTIVE DEBRIS CLOUD COVER BLOWING
DOWNSTREAM OF THE STALLED FRONT TOWARD NC/VA. WILL CONTINUE THE DRY
FORECAST INTO FRIDAY NIGHT AS ANY INSTABILITY WILL BE ELEVATED/WEAK
AND THE ONLY DECENT FORCING/LIFT REMAINS ALONG/WEST OF THE MOUNTAINS
IN THE TN/OH VALLEYS. LOW TEMPS WILL DEPEND ON THE AMOUNT OF
MID/UPPER LEVEL CONVECTIVE DEBRIS CLOUD COVER ACROSS THE AREA...BUT
OTHERWISE NEAR NORMAL TEMPS IN THE MID/UPPER 60S ARE EXPECTED.
SATURDAY:
FINALLY SEE SOME DECENT MOISTURE RETURNING TO THE AREA ON SAT...
WITH FCST SOUNDINGS SHOWING PWAT VALUES CLIMBING INTO THE 1.25-1.50"
RANGE BY SAT AFTERNOON...WITH THE HIGHEST VALUES IN THE WESTERN
PIEDMONT AND LOWEST IN THE COASTAL PLAIN. THE 12Z GFS/NAM SHOW THE
BROAD UPPER TROUGH OVER THE OHIO VALLEY AND MIDWEST SHARPENING OVER
THE OH/TN VALLEYS SAT AFTERNOON...ALTHOUGH THE GFS IS MUCH STRONGER
AND ACTUALLY SHOWS AN UPPER LOW DEVELOPING. EITHER WAY...BOTH MODELS
SEEM TO KEEP THE BETTER UPPER LEVEL LIFT FAR ENOUGH WEST OF CENTRAL
NC THAT WE SHOULD SEE ONLY SMALL CHANCES FOR CONVECTION SAT
AFTERNOON (LOW CHANCE WEST AND SLIGHT CHANCE EAST)...WITH THE
PRIMARY CONVECTIVE TRIGGERS LIKELY TO BE DIURNAL HEATING IN
COMBINATION WITH LOW LEVEL CONVERGENCE ASSOC/W SFC TROUGHING ACROSS
THE AREA. ADDITIONALLY...ANY ACTIVITY IN THE MOUNTAINS COULD
CONCEIVABLY PROPAGATE EAST INTO THE FOOTHILLS AND WESTERN PIEDMONT
DURING THE AFTERNOON GIVEN WEST/WSW FLOW IN THE MID/UPPER LEVELS.
THIS IS WHY THE BETTER CHANCE OF CONVECTION IS BEING FORECAST IN THE
WESTERN PIEDMONT SAT AFTERNOON. HIGH TEMPS ON SAT SHOULD BE A FEW
DEGREES LOWER THAN ON FRIDAY GIVEN INCREASED CLOUD COVER EXPECTED.
THIS SHOULD YIELD A RANGE FROM THE UPPER 80S TO LOWER 90S. -VINCENT
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 200 PM WEDNESDAY...
MID LEVEL TROUGH WILL LIFT EAST NORTHEAST OUT OF THE LOWER OHIO
VALLEY SATURDAY NIGHT AND SUNDAY...BRINGING THE BEST CHANCE FOR
WIDESPREAD RAINS TO CENTRAL NORTH CAROLINA IN SEVERAL DAYS.
AS THE TROUGH FLATTENS AND LIFTS NORTH MONDAY. ENOUGH ATMOSPHERIC
MOISTURE WILL REMAIN TO CONTINUE RAIN CHANCES...WITH THE BETTER
CHANCES IN THE EAST.
BROAD TROUGH PERSISTS OVER THE EAST COAST INTO WEDNESDAY. TIMING OF
ANY SHORT WAVE ENERGY THROUGH THE BASE OF THIS TROUGH IS SUSPECT
AT BEST. IT SAFE AT THIS TIME TO KEEP AFTERNOON RAIN CHANCES ABOVE
NORMAL TUESDAY AND WEDNESDAY...KNOWING THAT SHORT WAVE ENERGY WILL
EVENTUALLY BE RESOLVED BY THE MODELS TO FAVOR ONE PERIOD OVER THE
OTHER.
LOW TEMPERATURES SHOULD BE MOSTLY IN THE 69 TO 74 DEGREE RANGE
WITH ATMOSPHERIC MOISTURE AND CLOUDS GENERALLY ABOVE NORMAL.
AFTERNOON HIGHS NOT FAR FROM NORMAL AT 88 TO 93.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 145 AM THURSDAY...
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD... AS DEEP LAYER
ATMOSPHERIC MOISTURE IS EXCEPTIONALLY LOW FOR EARLY JULY... AND
FORECAST TO ONLY MARGINALLY INCREASE ON THURSDAY. OF MORE CONCERN...
WILL BE THE DEVELOPMENT OF A NOCTURNAL LOW LEVEL JET BETWEEN 1500
AND 2000 FT THIS MORNING AND AGAIN THURSDAY AND FRIDAY NIGHTS. IN
FACT... BOTH THE DIVISION OF AIR QUALITY AND THE NWS RADAR DERIVED
WIND PROFILE DATA INDICATE THAT A 220 DEGREE... 30 KT LLJ HAS
DEVELOPED OVER CENTRAL NC THIS MORNING. WHILE THE LLJ IS NOT
EXPECTED TO STRENGTHEN BEYOND ITS CURRENT SUB-CRITERIA 30 KT
STRENGTH... THE ASSOCIATED WIND SHEAR MAY PROVIDE FOR A LITTLE
TURBULENCE... NONETHELESS... ESPECIALLY FOR SMALLER AIRCRAFT. -MWS
VFR CONDITIONS THROUGH THE BALANCE OF THE WORK WEEK. UNSETTLED
WEATHER FOR THE HOLIDAY WEEKEND AS SOUTHERLY FLOW STRENGTHENS OVER
THE REGION...WITH THE APPROACH OF THE UPPER TROUGH FROM THE NW.
THIS WILL BRING THE CHANCE OF WIDESPREAD SHOWERS AND THUNDER...LATE
SATURDAY THROUGH MONDAY...POSSIBLY RESULTING IN A PERIOD OF MVFR
CONDITIONS IN HEAVIER PRECIPITATION. -CBL
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...VINCENT
LONG TERM...RLH
AVIATION...MWS/CBL
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
1003 AM EDT THU JUL 3 2008
.DISCUSSION...
RIDGE OF HIGH PRESSURE REMAINS OVER THE SOUTHERN APPALACHIANS. DEWPOINTS
HAVE RECOVERED SOME THIS MORNING...BUT THIS MORNING`S BNA SOUNDING
AND MDCRS PLOTS SHOWS BOUNDARY LAYER STILL DRY. STILL A WEAK CAP
NOTED AROUND 700MB AS WELL...SO DRY CONDITIONS WILL PREVAIL THIS
AFTERNOON AND EVENING.
CURRENT TEMPERATURE FORECAST LOOKS GOOD.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 91 64 88 70 84 / 10 10 40 40 60
KNOXVILLE MCGHEE TYSON AIRPORT, TN 90 65 88 68 83 / 10 10 50 50 60
OAK RIDGE, TN 91 64 87 67 84 / 10 10 50 50 60
TRI CITIES AIRPORT, TN 86 57 87 64 82 / 10 10 50 70 60
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
DH
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
736 AM EDT THU JUL 3 2008
.AVIATION...
MAIN FEATURES ARE LARGE BERMUDA HIGH PRESSURE OUT IN ATLANTIC AND
COLD FRONT THAT STRETCHES FROM CENTRAL MICHIGAN SW INTO SERN KS.
BETWEEN THESE TWO FEATURES...GENERALLY SOUTH OR SOUTHWEST FLOW
ACROSS MOST OF THE SOUTHEAST U.S. THE COLD FRONT HEADS
SOUTHEAST...AND GETS INTO KENTUCKY BY 12Z FRIDAY. PATTERN SOMEWHAT
AFFECTED BY DEVELOPMENT OF SURFACE LEE TROUGH...EAST OF THE
APPALACHIANS TODAY THAT LOOSENS PRESSURE GRADIENT...AND THEREFORE
LIGHTENS THE WINDS...ESPECIALLY NORTHEAST.
FOR THIS MORNING...AIRCRAFT SOUNDING AT KTRI CONFIRMS DRY AIR JUST
OFF THE GROUND...SFC DEW POINT = 53...BUT AT 850 MB...OR FL050 DEW
POINT WAS 38 DEGREES. SAME AIR MASS GENERALLY DOWN THROUGH
KCHA...ALTHOUGH A LITTLE MORE MOISTE WHERE PATCHY FOG IS REPORTED.
THIS FOG SHOULD NOT LAST LONG AS DRY AIR GETS MIXED DOWN QUICKLY
AND DISSIPATES FOG...WILL NOT INCLUDE IN TAF. THINK THERE WILL BE
ENOUGH MOISTURE RETURN TONIGHT TO ALLOW SOME LIGHT FOG AT KTRI.
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
GM
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