Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/19/13
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NWS LOS ANGELES/OXNARD CA
815 PM PDT SUN AUG 18 2013
.SYNOPSIS...
A SLIGHT CHANCE FOR THUNDERSTORMS ARE POSSIBLE IN THE SAN GABRIEL
MOUNTAINS AND ANTELOPE VALLEY AGAIN TOMORROW...WITH THE UPPER LOW
OFF THE CALIFORNIA COAST CONTINUING TO PULL SOME MONSOON MOISTURE
INTO THE AREA FROM THE SOUTHEAST. THE UPPER LOW WILL BEGIN TO LIFT
NORTHEAST ON THURSDAY...BUT WILL BE REPLACED BY ANOTHER TROUGH OF
LOW PRESSURE MOVING IN FROM THE NORTHWEST. THE RESULT WILL BE
CONTINUED NEAR OR SLIGHTLY BELOW NORMAL TEMPERATURES AND NIGHT
THROUGH MORNING LOW CLOUDS ALONG THE COAST.
&&
.SHORT TERM (TODAY-WED)...
A FEW VERY IMPRESSIVE THUNDERSTORMS DEVELOPED ACROSS THE NORTHEAST
PORTION OF LOS ANGELES COUNTY...MAINLY NORTH AND EAST OF PALMDALE
TODAY. A COUPLE STORM CELLS WERE RIGHT ON THE LOS ANGELES...SAN
BERNARDINO AND KERN COUNTY BORDER. CLOUD TOPS WERE AS HIGH AS 45000
FT WITH VERY IMPRESSIVE RAIN AND HAIL CORES EARLIER THIS AFTERNOON.
LATEST NWS RADAR WAS SHOWING MOST OF THE CONVECTIVE ACTIVITY
OCCURRING IN THE EASTERN PART OF SAN BERNARDINO COUNTY AND NORTH
INTO KERN COUNTY OVER THE LAST HOUR AND LIKELY SETTLING DOWN OVER
OUR AREA. MANY PARAMETERS CAME TOGETHER THIS AFTERNOON TO CAUSE
THESE EXPLOSIVE THUNDERSTORMS. ALTHOUGH PRECIPITABLE WATERS (PWAT)
VALUES WERE NOT THAT IMPRESSIVE AROUND 1.20" AND BEST MID LEVEL
MOISTURE WAS ABOVE 600 MB (ABOVE 12000 FT). THE INSTABILITY LOOKED
VERY IMPRESSIVE BY MID MORNING AS RAP SOUNDINGS OVER THE MOUNTAINS
INDICATED CAPE VALUES WELL OVER 1000 J/KG. SINCE STORMS WERE ABLE TO
INITIATE...THEY HAD NO PROBLEM GROWING VERTICALLY. RADAR RETURNS
INDICATED VERY HIGH VIL (VERTICAL INTEGRATED LIQUID) AVAILABLE WITH
THE STORM WHICH WAS A GOOD REASON WHY THERE WAS NICKEL SIZE HAIL
REPORTED IN SOME HIGH DESERT LOCATIONS THIS AFTERNOON.
BY LOOKING AT THE WATER VAPOR IMAGERY...IT IS EASY TO SPOT THE
DIFFLUENT REGION OVER EASTERN LA COUNTY AND POINTS EAST AND NORTH
BASED ON WHERE THE UPPER LOW WAS SITUATED TO HELP LIFT THESE STORMS
AND EXPLODE LIKE THEY DID. THERE WAS AN IMPRESSIVE LANDSPOUT
SPOTTED NEAR HELENDALE WHICH IS NORTH OF VICTORVILLE IN SAN
BERNARDINO COUNTY. AS THE UPPER LOW BEGINS TO PIVOT FARTHER OFFSHORE
THIS EVENING...THERE LOOKS TO BE SOME POTENTIAL FOR A FEW NOCTURNAL
SHOWERS OVER THE COASTAL WATERS N OF POINT CONCEPTION. I MIGHT ADD
SLIGHT CHANCE FOR THUNDERSTORMS FOR AREAS N OF POINT
CONCEPTION...BUT NOT VERY CONFIDENT. AS FAR AS THE LOWER AND MORE
STABLE PART OF THE ATMOSPHERE...(THE MARINE LAYER) WAS AROUND 1000
FT DEEP EARLY THIS EVENING...WHICH IS A BIT DEEPER THEN LAST NIGHT.
WITH THE UPPER LOW JUST OFF THE CENTRAL COAST...THERE WILL BE A
SLIGHT DEEPENING OF THE MARINE LAYER WHICH WILL ALLOW FOR SOME LOW
CLOUDS TO CREEP INTO THE SAN GABRIEL AND POSSIBLY THE SAN FERNANDO
VALLEY AFTER MIDNIGHT. TODAY`S HIGH TEMPS WERE OVERALL A TAD
LOWER...BUT A FEW INTERIOR AREAS WERE AROUND THE SAME AS YESTERDAY.
LONG BEACH WAS MUCH COOLER TODAY AT ONLY 74 COMPARED TO 86 ON
SATURDAY DUE TO A PERSISTENT SOUTHERLY FLOW AND LOW CLOUDS HANGING
AROUND.
FOR MONDAY...NOT MUCH MOVEMENT IS EXPECTED WITH CUTOFF LOW...BUT
THERE WILL CONTINUE TO BE SOME MODEST MID LEVEL MOISTURE ADVECTING
NORTH OVER EASTERN LA COUNTY AND AREAS TO THE EAST. BOTH THE NAM-WRF
AND GFS ARE INDICATING MORE INSTABILITY OVER THE LA COUNTY
MOUNTAINS...HAVE ADDED A SLIGHT CHANCE OF THUNDERSTORMS FOR THE
EASTERN PORTION OF THE SAN GABRIEL VALLEY AND ANTELOPE VALLEY ONCE
AGAIN. THERE WILL BE LESS MOISTURE TO WORK WITH...BUT A SLIGHT
CHANCE SEEMS REASONABLE FOR TOMORROW AFTERNOON AND EARLY EVENING. AT
THE LEAST EXPECT PARTLY CLOUDY SKIES WITH SOME CUMULUS BUILDUPS IN
THE MOUNTAINS AND OVER THE ANTELOPE VALLEY. LOOK FOR A MODEST
COOLING TREND FOR TOMORROW AS THE UPPER RIDGE WEAKENS A
BIT...ESPECIALLY ACROSS THE NORTHERN PORTION OF THE FORECAST AREA N
OF POINT CONCEPTION. THERE WILL LIKELY BE SOME HIGH CLOUDS MOVING
TO THE NORTH ACROSS THE SKY...BUT WILL CONTINUE WITH MOSTLY SUNNY
SKIES. THE MID SHIFT CAN ADJUST IF NEED BE.
***FROM PREVIOUS DISCUSSION***
VERY LITTLE CHANGE TUE/WED. POSSIBLY SOME HIGH CLOUDS MOVING THROUGH
AT TIMES TUESDAY AS MOISTURE WRAPS AROUND THE STILL STATIONARY UPPER
LOW. BUT AT THIS TIME NOT SEEING ANYTHING TO WARRANT POPS OR EVEN
PARTLY CLOUDY SKIES. DAYTIME HIGHS EXPECTED TO CHANGE LITTLE.
.LONG TERM (THU-SUN)...UPPER LOW FINALLY EXITING THE STATE ON
THURSDAY TO BE REPLACED BY A WEAK TROF THROUGH THE WEEKEND. THE
ECMWF IS DEEPER WITH THE TROF AND THUS COOLER AS WELL. FOR NOW WILL
JUST INDICATE LITTLE CHANGE THROUGH THE PERIOD WITH HIGHS NEAR TO
SLIGHTLY BELOW SEASONAL NORMS. ALL MODEL SOLUTIONS KEEP MONSOON
MOISTURE WELL EAST INTO EARLY NEXT WEEK.
&&
.FIRE...
A CUTOFF LOW PRESSURE SYSTEM OFF THE CENTRAL COAST WILL REMAIN
NEARLY STATIONARY THROUGH TUESDAY. THIS LOW PRESSURE SYSTEM IS
DRAWING SOME MOISTURE INTO SOUTHERN AND CENTRAL CALIFORNIA. AT THE
PRESENT TIME...THE MOISTURE AXIS IS FOCUSED ACROSS EASTERN LOS
ANGELES COUNTY AND POINTS EASTWARD. THIS INFLUX OF MOISTURE COMBINED
WITH AN UNSTABLE AIR MASS WILL CONTINUE TO GENERATE ISOLATED
THUNDERSTORMS ACROSS THE EASTERN PORTIONS OF THE SAN GABRIEL
MOUNTAINS AND ANTELOPE VALLEY THROUGH THIS EVENING. THESE STORMS
WILL HAVE THE POTENTIAL TO PRODUCE STRONG DOWNDRAFT
WINDS...HAIL...AND BRIEF HEAVY DOWNPOURS. AROUND THE PERIPHERY OF
STORMS...ISOLATED DRY LIGHTNING STRIKES WILL BE POSSIBLE. CLOSER TO
THE CLOSED LOW...THERE IS A VERY SLIGHT CHANCE OF STORMS TONIGHT
INTO MONDAY FOR AREAS NORTH OF POINT CONCEPTION.
THE LOW PRESSURE SYSTEM WILL BRING GUSTY SOUTHERLY WINDS TO INTERIOR
SECTIONS THROUGH MONDAY. WITH THE EXCEPTION OF EASTERN LOS ANGELES
COUNTY...REMAINING AREAS ARE FORECASTED TO BE QUITE DRY AT LOWER
ELEVATIONS. THIS COMBINATION OF GUSTY SOUTHERLY WINDS...LOW
HUMIDITIES...VERY WARM TEMPERATURES...AND VERY DRY FUELS WILL
CONTINUE TO BRING ELEVATED FIRE DANGER ACROSS INLAND AREAS THROUGH
MONDAY. BRIEF CRITICAL FIRE WEATHER CONDITIONS WILL BE LIKELY
THROUGH MONDAY ACROSS THE MOUNTAINS.
&&
.AVIATION...19/00Z.
WILL GO WITH PERSISTENCE ONCE AGAIN IN RESPECT TO STRATUS AND FOG
OVER THE NEXT 24 HOURS. HIGH CONFIDENCE WITH LIFR/IFR CIGS FOR
COASTAL AREAS...WITH SOME VLIFR CONDS FOR A FEW COASTAL SITES.
TIMING FOR LOW CLOUDS WILL BE MODERATE IN CONFIDENCE +/-2 HOURS AS
WELL AS SCOUR OUT TIMES MON MORNING. LATEST AMDAR SOUNDING NEAR KLAX
SHOWED A STRONG INVERSION AROUND 1200 FT DEEP. WITH THE MARINE LAYER
THIS DEEP...THERE WILL BE A 30 PERCENT CHANCE THAT KBUR AND KVNY
WILL EXPERIENCE IFR/LIFR CIGS AFTER 10Z TONIGHT.
KLAX...HIGH CONFIDENCE FOR IFR/MVFR CIGS TO PERSIST THROUGH THE
OVERNIGHT HOURS. 30 PERCENT CHANCE FOR CIGS TO SCOUR OUT +/- W HOURS
FROM 00Z TAF.
KBUR...HIGH CONFIDENCE WITH 00Z TAF THROUGH 10Z. THEN 30 PERCENT
CHANCE FOR LIFR/IFR CIGS AFTER 10Z THROUGH 15Z.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
PUBLIC...KAPLAN/MW
FIRE...GOMBERG
AVIATION...CK
SYNOPSIS...SUKUP
WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION...UPDATED
NWS RENO NV
802 PM PDT SUN AUG 18 2013
.UPDATE...SHORT TERM AND FIRE WEATHER
UPDATED FORECAST TO INCLUDE ISOLATED THUNDERSTORMS NORTHERN AREAS
THIS EVENING AS CONVECTION WAS DEVELOPING OVER FAR NORTHERN WASHOE
COUNTY. STORMS HAVE PRODUCED SIGNIFICANT AMOUNTS OF LIGHTNING MUCH
LIKE THEY DID SATURDAY. SATELLITE AND RADAR IMAGERY SHOWS
SHORTWAVE MOVING NORTHWEST INTO WESTERN NV THIS EVENING AND THIS
WILL LIKELY RESULT IN ANOTHER ROUND OF THUNDERSTORMS THIS EVENING
ESPECIALLY SOUTH OF HIGHWAY 50. ADDED THUNDERSTORMS OVERNIGHT AS
WELL GIVEN THE ELEVATED INSTABILITY AND LIFT, ALTHOUGH COVERAGE OF
LIGHTNING SHOULD DECREASE. THUNDERSTORMS WILL BE MORE ELEVATED
OVERNIGHT AND MORE CONDUCIVE TO DRY STRIKES.
THE OTHER PROBLEM WILL BE THE SMOKE AS OUTFLOW PUSHED SMOKE BACK
INTO THE RENO-CARSON CITY AREA. OUTFLOW WAS COLLIDING WITH GUST
FRONT AND ASSOCIATED DUST MOVING WESTWARD THROUGH PERSHING AND
CHURCHILL COUNTIES. VISIBILITY IN BOTH AREAS HAS BEEN AS LOW AS 2
MILES, POSSIBLY LOWER IN LOCALIZED AREAS. UNFORTUNATELY THE EAST
OUTFLOW WILL MOST LIKELY NOT MAKE IT FAR ENOUGH WEST TO PUSH THE
SMOKE BACK OUT OF THE AREA. SO WE WILL HAVE TO WAIT FOR MIXING AND
SOUTHEAST FLOW TO HELP THINGS IMPROVE ON MONDAY. SO UPDATED TO PUT
SMOKE ALONG THE SIERRA FRONT AND TAHOE BASIN THROUGH MONDAY
MORNING. HOHMANN
&&
.PREVIOUS DISCUSSION... /ISSUED 201 PM PDT SUN AUG 18 2013/
SYNOPSIS...
SHOWERS AND THUNDERSTORMS WILL INCREASE THIS AFTERNOON AND
CONTINUE THROUGH THURSDAY AS LOW PRESSURE OFF THE CENTRAL
CALIFORNIA COAST REMAINS IN PLACE BEFORE MOVING INLAND BY MIDWEEK.
THE STRONGER STORMS WILL PRODUCE HEAVY RAINFALL, HAIL AND FREQUENT
LIGHTNING. ABOVE NORMAL TEMPERATURES ARE EXPECTED ON MONDAY,
BEFORE COOLING BACK TO NEAR SEASONAL NORMALS FOR THE REMAINDER OF
THE UPCOMING WEEK.
SHORT TERM...
CURRENT WATER VAPOR IMAGERY SHOWS THE UPPER LOW PARKED JUST OFF
THE CALIFORNIA COASTLINE NEAR MONTEREY BAY. SOUTHERLY FLOW
BETWEEN THIS LOW AND HIGH PRESSURE ACROSS SOUTHERN NEW MEXICO HAS
ALLOWED MOISTURE TO SURGE NORTH ACROSS SOUTHERN CALIFORNIA AND
SOUTHERN NEVADA WITH THE 12Z RAOB AT LAS VEGAS REPORTING A
PRECIPITABLE WATER VALUE OF 1.17 INCHES.
MODEL GUIDANCE IS IN GOOD AGREEMENT THAT THE UPPER LOW WILL
REMAIN JUST OFF THE CENTRAL CALIFORNIA COASTLINE THROUGH
WEDNESDAY WITH MOISTURE INCREASING ACROSS THE SIERRA AND WESTERN
NEVADA. THE MAIN CHALLENGE IN THE SHORT TERM WILL BE TIMING THE
INDIVIDUAL SHORT WAVES THAT ROTATE AROUND THE UPPER LOW AND PROVIDE
FORCING FOR THUNDERSTORM ACTIVITY.
THE BEST CHANCE OF THUNDERSTORMS THIS AFTERNOON WILL BE NEAR THE
SIERRA CREST IN MONO AND ALPINE COUNTIES. RECENT RUNS OF THE SHORT
TERM HRRR MODEL SUGGEST A BROADER AREA OF CONVECTION WILL DEVELOP
ACROSS MONO AND MINERAL COUNTIES AND LIFT TO THE NORTHWEST TOWARDS
THE INTERSTATE 80 CORRIDOR THIS EVENING. THE 12Z NAM DEPICTS A
VERY WEAK SHORTWAVE ROTATING AROUND THE UPPER LOW ACROSS WESTERN
NEVADA THIS EVENING WHICH MAY ACT AS THE FORCING FOR THIS
CONVECTION. GIVEN THE RUN TO RUN CONSISTENCY OF THE HRRR THIS
MORNING...DECIDED TO INCREASE POPS ACROSS MONO AND MINERAL
COUNTIES THROUGH MIDNIGHT.
SCATTERED THUNDERSTORMS ARE POSSIBLE ACROSS THE ENTIRE FORECAST
AREA ON MONDAY AS MODEL PRECIPITABLE WATER VALUES INCREASE TO 0.75
INCHES NEAR RENO. WITH THE STORMS TURNING WETTER AND STORM MOTIONS
AROUND 10 KTS, THE MAIN CONCERN WILL BE LOCALLY HEAVY RAIN AND
THE POTENTIAL FOR FLASH FLOODING. MOISTURE WILL INCREASE FURTHER
ON TUESDAY WITH MODEL PRECIPITABLE WATER VALUES NEAR 0.95 INCHES
ACROSS WESTERN NEVADA. A FLASH FLOOD WATCH MAY BE NECESSARY ON
TUESDAY AS THE DEEP MOISTURE WILL BE WELL ESTABLISHED AND STORM
MOTIONS WILL REMAIN SLOW (AROUND 10 KTS).
AREAS OF SMOKE HAVE BEEN ADDED TO THE FORECAST GRIDS FOR THIS
AFTERNOON AND EVENING IN THE CARSON AND WASHOE VALLEYS DUE TO THE
BRUNSWICK FIRE LOCATED TO THE EAST OF CARSON CITY. ALSO INCLUDED
MENTION OF SMOKE ACROSS PORTIONS OF SOUTHERN LYON, WESTERN MINERAL
AND EAST CENTRAL MONO COUNTIES THANKS TO SPRING PEAK WILDFIRE
LOCATED TO THE EAST OF BODIE. MYRICK
LONG TERM...WEDNESDAY THROUGH SUNDAY...
THERE IS STILL GOOD AGREEMENT AMONG MEDIUM RANGE MODELS WITH THE LOW
LIFTING NORTH ACROSS NORTHERN CALIFORNIA WEDNESDAY INTO THURSDAY AND
MOVING INTO SOUTHERN OREGON AS AN OPEN WAVE BY THURSDAY NIGHT OR
FRIDAY MORNING. THUNDERSTORMS WILL CONTINUE TO BE A THREAT THROUGH
THURSDAY WITH THE BEST CHANCES IN NORTHEAST CALIFORNIA AND NORTHWEST
NEVADA NORTH OF HIGHWAY 50 WHERE THERE IS DIFLUENT FLOW ALOFT AND
THE BEST DYNAMICS AND LIFT. HEAVY RAIN IS THE GREATEST CONCERN
WEDNESDAY AND THURSDAY AS PRECIPITABLE WATER VALUES REMAIN AT
0.8-1.0 INCH. WHILE STORM MOTIONS DO INCREASE BY THURSDAY, TRAINING
AND/OR BACK BUILDING STORMS COULD STILL PRODUCE AREAS OF HEAVY RAIN.
HAIL AND GUSTY OUTFLOW WINDS ARE ALSO POSSIBLE.
DRY AND STABLE SOUTHWEST FLOW RESULTS ACROSS THE AREA BEHIND THE
EXITING LOW, ENDING ALL THUNDERSTORM CHANCES THROUGH THE WEEKEND AND
KEEPING SKIES MOSTLY CLEAR. BREEZY AFTERNOON WINDS ARE EXPECTED EACH
DAY, BUT GUSTS SHOULD BE AT OR BELOW 30 MPH. TEMPERATURES WILL BE
SLIGHTLY BELOW NORMAL WEDNESDAY AND THURSDAY, ESPECIALLY ACROSS
NORTHEAST CALIFORNIA CLOSER TO THE CORE OF THE LOW. HIGHS WILL
REBOUND TO NEAR NORMAL FOR THE WEEKEND. DJ
AVIATION...
CONVECTIVE TOWERS HAVE DEVELOPED THIS AFTERNOON ALONG THE SIERRA
CREST SOUTH OF LAKE TAHOE. THE BEST CHANCE OF STORMS THROUGH 00Z
WILL BE AT KMMH, KTRK AND KTVL. THE MAIN THREATS FROM ANY STORMS
THAT FORM WILL BE ERRATIC AND GUSTY WINDS, LOCALLY HEAVY RAIN AND
SMALL HAIL. A COMPLEX OF SHOWERS AND THUNDERSTORMS MAY LIFT
NORTHWEST ACROSS WESTERN NEVADA BETWEEN 00-09Z IMPACTING KCXP AND
KRNO, BUT CONFIDENCE IN TIMING AND LOCATION AT THIS TIME IS LOW.
SMOKE FROM THE BRUNSWICK FIRE TO THE EAST OF CARSON CITY MAY
REDUCE SLANTWISE VISIBILITIES AT KCXP AND KRNO THROUGH THIS
EVENING.
THUNDERSTORM CHANCES INCREASE AT ALL TERMINALS ON MONDAY AND
TUESDAY AS A SLOW MOVING AREA OF LOW PRESSURE REMAINS PARKED OFF
THE CENTRAL CALIFORNIA COAST WITH DEEP MOISTURE IN PLACE ACROSS
THE SIERRA AND WESTERN NEVADA. MYRICK
&&
.REV WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
CA...NONE.
&&
$$
FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/RENO (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1042 PM EDT SUN AUG 18 2013
.SYNOPSIS...
LOW PRESSURE WILL TRACK SOUTHEAST OF LONG ISLAND TONIGHT. A
SURFACE TROUGH ACROSS THE AREA ON MONDAY WILL WEAKEN MONDAY NIGHT
AND TUESDAY AS HIGH PRESSURE STARTS TO BUILD IN FROM THE WEST AND
SOUTH. THIS HIGH PRESSURE CENTERED TO OUR SOUTH WILL GRADUALLY
WEAKEN THROUGH THE MIDDLE OF THE WEEK. A COLD FRONT WILL MOVE
THROUGH THE AREA LATE THU NIGHT OR FRI MORNING WITH HIGH PRESSURE
RETURNING IN ITS WAKE.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A WEAK LOW PRESSURE SYSTEM REMAINS WELL EAST OF THE DELMARVA COAST
AND WILL CONTINUE TO TRACK NE OVERNIGHT. RAIN HAS MOVED OUT OF THE
AREA AND TOOK OUT ALL POPS EXCEPT FOR A SLIGHT CHANCE MENTION OVER
EASTERN LONG ISLAND AS THE RAIN IS STILL MOVING OUT IN THAT AREA.
THE NEXT THING THAT WILL NEED WATCHING IS AN AREA OF CONVECTION
CURRENTLY OVER SOUTHERN W VA...ASSOCIATED WITH AN UPPER LEVEL
SHORTWAVE. THE NAM/GFS AND HRRR ALL INDICATE THIS APPROACHES LATE
TONIGHT...BUT KEEP ANY MEASURABLE PRECIP TO OUR W (THE HRRR ENDS
AT 11Z WITH IT OVER ERN PA)
CLOUDS WILL DECREASE OVERNIGHT BUT HOW MUCH REMAINS QUESTIONABLE
DUE TO THE APPROACHING SHORTWAVE ENERGY/PRECIP. AS A
RESULT...RADIATIONAL COOLING MAY BE MORE LIMITED THAN PREVIOUSLY
THOUGHT.
LOWS ARE EXPECTED TO RANGE MOSTLY FROM THE LOWER 50S TO LOWER
60S...A FEW DEGREES WARMER IN THE NEW YORK CITY METRO
AREA. DID RAISE MIN TEMPS ON THIS UPDATE AS CLOUD COVER REMAINS
OVER THE AREA.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
FOR MONDAY...EXPECTING CONSIDERABLE MID AND UPPER LEVEL CLOUDS
AHEAD OF THE NEXT SHORTWAVE. THIS WILL MITIGATE DAYTIME WARMTH BUT
THE GREATER WESTERLY LOW LEVEL FLOW WILL ENABLE BETTER ADIABATIC
MIXING UP TO AROUND 900MB. IT WILL BE WARMEST ACROSS THE URBAN AND
VALLEY CORRIDORS AND A FEW DEGREES COOLER AT THE COAST WITH MORE
ONSHORE FLOW.
THE UPPER LEVEL JET MOVES ACROSS THE REGION WITH ITS ENTRANCE REGION
MOVING ACROSS LATE IN THE DAY INTO THE EVENING. WE ARE NOT NEAR THE
FAVORABLE RIGHT ENTRANCE REGION OF THIS JET BUT CONSIDERING THE
STRONGER SHORTWAVE AND ADDITION OF DAYTIME INSTABILITY...A SHOWER OR
THUNDERSTORM CANNOT BE RULED OUT. IN ADDITION...THE INDICATION OF
DAYTIME SURFACE TROUGH DEVELOPMENT COULD MEAN THAT WINDS COULD BE
MORE WEST OR NORTHWEST AWAY FROM THE COAST WITH MORE SOUTHERLY FLOW
AT THE COAST WITH SEA BREEZE POTENTIAL...THEREBY INCREASING THE
POTENTIAL FOR SURFACE CONVERGENCE.
FOR MONDAY NIGHT...THE UPPER LEVEL JET AND SHORTWAVE AXIS EXIT
SOUTHEAST OF THE REGION. THIS WILL ALLOW FOR HEIGHT RISES ALOFT
AND SURFACE HIGH PRESSURE WILL START TO BUILD IN FROM THE SOUTH
AND WEST. THIS WILL ALSO MARK A MODERATION OF THE AIRMASS TO ONE
MORE TYPICAL OF SUMMER AS TEMPS ALOFT INCREASE SLIGHTLY WITH THE
RIDGING. SO DESPITE THE LOWERING CLOUDS AND LIGHT WINDS...THE LOWS
WILL ACTUALLY BE A FEW DEGREES WARMER THAN THE PREVIOUS NIGHT.
FOR TUESDAY...A CONTINUED WARMING TREND WITH 850MB TEMPS
INCREASING 1-2 DEGREES C FROM THE DAY BEFORE WITH THE ADDED
SUPPORT OF CONTINUED SUBSIDENCE...ALLOWING FOR MORE SUNSHINE.
WINDS WILL BE SIMILAR TO THE DAY BEFORE BUT A FEW KNOTS LIGHTER IN
SPEED.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
LATEST MODELS/ENSEMBLES CONTINUE TO ADVERTISE A GRADUAL
AMPLIFICATION OF THE PATTERN DURING THE MEDIUM RANGE PERIOD...
WITH TROUGHS SETTLING OVER THE ERN PACIFIC AND CANADIAN
MARITIMES/EXTREME WRN ATLC. AT THE SAME TIME A MEAN RIDGE SHOULD
DRIFT SLOWLY EWD FROM THE PLAINS/SRN ROCKIES WHILE ANOTHER RIDGE
SHOULD REMAIN CENTERED OFF THE SERN COAST TO THE N OF THE BAHAMAS.
ALTHOUGH THERE IS GOOD AGREEMENT/CONTINUITY WITH THE FCST FOR
LARGE SCALE FLOW...SPREAD WITH THE TIMING AND AMPLITUDE OF
INDIVIDUAL SHRTWVS WITHIN THE FLOW FROM THE ERN PAC ACROSS SRN
CANADA/NRN TIER CONUS PRESENTS PROBLEMS FOR DETERMINING THE EXACT
POSITION OF THE MEAN SFC BOUNDARY EXPECTED TO SET UP FROM THE NRN
PLAINS INTO THE MID ATLC. SUCH DETAILS ARE TYPICALLY NOT EASILY
RESOLVED IN THE MEDIUM RANGE TIME FRAME SO HAVE LEANED TOWARDS WPC
GUIDANCE WHICH CONSISTS OF A BLEND OF THE 06Z GEFS/00Z ECMWF MEANS
WITH MINOR DETAIL ENHANCEMENTS. THIS SOLN PROVIDES BETTER
CONTINUITY THAN MOST OPERATIONAL MODELS AT THIS TIME.
WITH LEADING HGT FALLS CROSSING THE ERN HALF OF SRN CANADA DURING
THE FIRST HALF OF THE PERIOD THE 00Z ECMWF STARTS LEANING TOWARD THE
FASTER/AMPLIFIED SIDE OF THE SPREAD BY LATE THU-FRI...WHILE IN
VARYING WAYS THE 00Z GFS/CMC BECOME FAIRLY AMPLIFIED WITH THEIR ERN
NOAM TROUGH ALBEIT WITHIN THE ENSEMBLE SPREAD. THE PREFERRED
ENSEMBLE MEANS TONE DOWN TROUGH AMPLITUDE AND SEWD PROGRESSION OF
THE LEADING COLD FRONT SLIGHTLY.
UPSTREAM DIFFS AT THE SFC BECOME PRONOUNCED BY FRI AS RECENT ECMWF
RUNS HAVE BEEN TRYING TO BRING A WAVE INTO THE UPR MS VLY/UPR GRTLKS
WHILE GFS RUNS KEEP MUCH HIGHER PRESSURES IN PLACE OVER THE REGION.
THE 00Z UKMET HINTS AT AN ECMWF-TYPE WAVE BUT THE 00Z CMC AS WELL AS
LATEST GEFS/ECMWF/CMC MEANS ARE NOT VERY ENTHUSIASTIC ABOUT SUCH A
WAVE. ESPECIALLY GIVEN THE RELATIVELY FLAT NATURE OF THE MEAN FLOW
ALONG THE US-CANADIAN BORDER AT THAT TIME...WOULD PREFER TO SEE MORE
AGREEMENT FROM GUIDANCE BEFORE TRENDING TOWARD THE ECMWF SCENARIO.
THEREFORE LOCALLY...THE CONTINUATION OF BENIGN WEATHER IS EXPECTED
TO MOSTLY PREVAIL WITH MORE SUMMER LIKE TEMPERATURES DURING THE
MIDDLE OF THE WEEK. A FEW LOCATIONS IN METRO NY/NJ MAY REACH THE 90
DEGREE MARK BOTH WED AND THU...WHICH WILL BE THE FIRST TIME IN A
MONTH. HUMIDITY LEVELS WILL ALSO CREEP BACK UP WITH DEWPOINT
TEMPERATURES IN THE MID TO UPPER 60S. HEAT INDICES ARE EXPECTED TO
REMAIN BELOW 95 DEGREES. A PREFRONTAL TROUGH WILL SET UP W OF NYC ON
THU. ISOLD SHOWERS/POSSIBLE A TSTM MAY BE TRIGGERED N AND W OF
NYC...BUT HAVE KEPT THE FORECAST DRY AS PREDICTABILITY IS TOO LOW.
AS THE COLD FRONT WHICH IS PROGGED TO MOVE THROUGH LATE THU
NIGHT/FRI...THE CHC FOR SHOWERS/TSTMS WILL INCREASE ALTHOUGH HAVE
KEPT SCHC POPS AHEAD OF AND WITH ITS PASSAGE DUE TO THE
AFOREMENTIONED UNCERTAINTY. HAVE ALSO GONE WITH THE CONSENSUS NEXT
WEEKEND AND KEPT THE FORECAST DRY.
TEMPS WILL START OFF ABOVE NORMAL...THEN FALL BACK TO SEASONABLE
LEVELS AT THE END OF THE WEEK.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
LOW PRESSURE CONTINUE TO TRACK WELL TO THE SOUTHEAST TONIGHT. WEAK
HIGH PRESSURE RETURNS ON MONDAY
VFR. LIGHT AND VARIABLE THIS EVENING...THEN BECOMING LIGHT
WESTERLY TOWARDS DAYBREAK.
FOR MONDAY...WSW WINDS INCREASING TO AROUND 10 KT ACROSS WESTERN
TERMINALS...AND SW ACROSS COASTAL TERMINALS. SEABREEZE
DEVELOPMENT LIKELY ACROSS KJFK/KISP/KBDR/KGON. LOW PROBABILITY OF
SEABREEZE REACHING KLGA...AND NOT EXPECTED ELSEWHERE. BKN CIGS OF
AROUND 10-15 KFT LIKELY...WITH SCT 4-6 KFT CU.
OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY...
.MONDAY NIGHT-WEDNESDAY...VFR.
.THURS...CHC SUB-VFR AND TSTM.
.FRI...VFR.
&&
.MARINE...
SUB SCA CONDITIONS WILL PREVAIL ACROSS THE WATERS THROUGH TUESDAY.
THE PRESSURE GRADIENT WILL REMAIN WEAK ENOUGH TO LIMIT THE UPPER
EXTENT OF WIND SPEED TO AROUND 15 KT AND SEAS ON THE OCEAN WILL
STAY BETWEEN 2 AND 3 FT FOR MOST OF THE TIME. WAVEWATCH GUIDANCE
SEEMED TO BE AGREEING PRETTY WELL WITH CURRENT BUOY OBS IN TERMS
OF WAVE HEIGHT.
THE WINDS AND SEAS ARE FORECAST TO REMAIN BLO SCA LEVELS THROUGH
THE REST OF THE FORECAST PERIOD.
&&
.HYDROLOGY...
NO SIGNIFICANT WIDESPREAD RAIN IS EXPECTED. A FEW HUNDREDTHS OF AN
INCH OF ADDITIONAL QPF IS EXPECTED THIS EVE MAINLY ON EASTERN LONG
ISLAND AND SE CT.
&&
.EQUIPMENT...
THE NOAA ALL HAZARDS WEATHER RADIO TRANSMITTER IN NEW YORK CITY
HAS BEEN DE-ACTIVATED UNTIL FURTHER NOTICE.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...24/JM
NEAR TERM...JM/LN
SHORT TERM...JM
LONG TERM...24
AVIATION...NV
MARINE...24/JM
HYDROLOGY...24/JM
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
941 PM EDT SUN AUG 18 2013
.SYNOPSIS...
LOW PRESSURE WILL TRACK SOUTHEAST OF LONG ISLAND TONIGHT. A
SURFACE TROUGH ACROSS THE AREA ON MONDAY WILL WEAKEN MONDAY NIGHT
AND TUESDAY AS HIGH PRESSURE STARTS TO BUILD IN FROM THE WEST AND
SOUTH. THIS HIGH PRESSURE CENTERED TO OUR SOUTH WILL GRADUALLY
WEAKEN THROUGH THE MIDDLE OF THE WEEK. A COLD FRONT WILL MOVE
THROUGH THE AREA LATE THU NIGHT OR FRI MORNING WITH HIGH PRESSURE
RETURNING IN ITS WAKE.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A WEAK LOW PRESSURE SYSTEM REMAINS WELL EAST OF THE DELMARVA COAST
AND WILL CONTINUE TO TRACK NE OVERNIGHT. RAIN HAS MOVED OUT OF THE
AREA AND TOOK OUT ALL POPS EXCEPT FOR A SLIGHT CHANCE MENTION OVER
EASTERN LONG ISLAND AS THE RAIN IS STILL MOVING OUT IN THAT AREA.
THE NEXT THING THAT WILL NEED WATCHING IS AN AREA OF CONVECTION
CURRENTLY OVER SOUTHERN W VA...ASSOCIATED WITH AN UPPER LEVEL
SHORTWAVE. THE NAM/GFS AND HRRR ALL INDICATE THIS APPROACHES LATE
TONIGHT...BUT KEEP ANY MEASURABLE PRECIP TO OUR W (THE HRRR ENDS
AT 11Z WITH IT OVER ERN PA)
CLOUDS WILL DECREASE OVERNIGHT BUT HOW MUCH REMAINS QUESTIONABLE
DUE TO THE APPROACHING SHORTWAVE ENERGY/PRECIP. AS A
RESULT...RADIATIONAL COOLING MAY BE MORE LIMITED THAN PREVIOUSLY
THOUGHT.
LOWS ARE EXPECTED TO RANGE MOSTLY FROM THE LOWER 50S TO LOWER
60S...A FEW DEGREES WARMER IN THE NEW YORK CITY METRO
AREA. DID RAISE MIN TEMPS ON THIS UPDATE AS CLOUD COVER REMAINS
OVER THE AREA.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
FOR MONDAY...EXPECTING CONSIDERABLE MID AND UPPER LEVEL CLOUDS
AHEAD OF THE NEXT SHORTWAVE. THIS WILL MITIGATE DAYTIME WARMTH BUT
THE GREATER WESTERLY LOW LEVEL FLOW WILL ENABLE BETTER ADIABATIC
MIXING UP TO AROUND 900MB. IT WILL BE WARMEST ACROSS THE URBAN AND
VALLEY CORRIDORS AND A FEW DEGREES COOLER AT THE COAST WITH MORE
ONSHORE FLOW.
THE UPPER LEVEL JET MOVES ACROSS THE REGION WITH ITS ENTRANCE REGION
MOVING ACROSS LATE IN THE DAY INTO THE EVENING. WE ARE NOT NEAR THE
FAVORABLE RIGHT ENTRANCE REGION OF THIS JET BUT CONSIDERING THE
STRONGER SHORTWAVE AND ADDITION OF DAYTIME INSTABILITY...A SHOWER OR
THUNDERSTORM CANNOT BE RULED OUT. IN ADDITION...THE INDICATION OF
DAYTIME SURFACE TROUGH DEVELOPMENT COULD MEAN THAT WINDS COULD BE
MORE WEST OR NORTHWEST AWAY FROM THE COAST WITH MORE SOUTHERLY FLOW
AT THE COAST WITH SEA BREEZE POTENTIAL...THEREBY INCREASING THE
POTENTIAL FOR SURFACE CONVERGENCE.
FOR MONDAY NIGHT...THE UPPER LEVEL JET AND SHORTWAVE AXIS EXIT
SOUTHEAST OF THE REGION. THIS WILL ALLOW FOR HEIGHT RISES ALOFT
AND SURFACE HIGH PRESSURE WILL START TO BUILD IN FROM THE SOUTH
AND WEST. THIS WILL ALSO MARK A MODERATION OF THE AIRMASS TO ONE
MORE TYPICAL OF SUMMER AS TEMPS ALOFT INCREASE SLIGHTLY WITH THE
RIDGING. SO DESPITE THE LOWERING CLOUDS AND LIGHT WINDS...THE LOWS
WILL ACTUALLY BE A FEW DEGREES WARMER THAN THE PREVIOUS NIGHT.
FOR TUESDAY...A CONTINUED WARMING TREND WITH 850MB TEMPS
INCREASING 1-2 DEGREES C FROM THE DAY BEFORE WITH THE ADDED
SUPPORT OF CONTINUED SUBSIDENCE...ALLOWING FOR MORE SUNSHINE.
WINDS WILL BE SIMILAR TO THE DAY BEFORE BUT A FEW KNOTS LIGHTER IN
SPEED.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
LATEST MODELS/ENSEMBLES CONTINUE TO ADVERTISE A GRADUAL
AMPLIFICATION OF THE PATTERN DURING THE MEDIUM RANGE PERIOD...
WITH TROUGHS SETTLING OVER THE ERN PACIFIC AND CANADIAN
MARITIMES/EXTREME WRN ATLC. AT THE SAME TIME A MEAN RIDGE SHOULD
DRIFT SLOWLY EWD FROM THE PLAINS/SRN ROCKIES WHILE ANOTHER RIDGE
SHOULD REMAIN CENTERED OFF THE SERN COAST TO THE N OF THE BAHAMAS.
ALTHOUGH THERE IS GOOD AGREEMENT/CONTINUITY WITH THE FCST FOR
LARGE SCALE FLOW...SPREAD WITH THE TIMING AND AMPLITUDE OF
INDIVIDUAL SHRTWVS WITHIN THE FLOW FROM THE ERN PAC ACROSS SRN
CANADA/NRN TIER CONUS PRESENTS PROBLEMS FOR DETERMINING THE EXACT
POSITION OF THE MEAN SFC BOUNDARY EXPECTED TO SET UP FROM THE NRN
PLAINS INTO THE MID ATLC. SUCH DETAILS ARE TYPICALLY NOT EASILY
RESOLVED IN THE MEDIUM RANGE TIME FRAME SO HAVE LEANED TOWARDS WPC
GUIDANCE WHICH CONSISTS OF A BLEND OF THE 06Z GEFS/00Z ECMWF MEANS
WITH MINOR DETAIL ENHANCEMENTS. THIS SOLN PROVIDES BETTER
CONTINUITY THAN MOST OPERATIONAL MODELS AT THIS TIME.
WITH LEADING HGT FALLS CROSSING THE ERN HALF OF SRN CANADA DURING
THE FIRST HALF OF THE PERIOD THE 00Z ECMWF STARTS LEANING TOWARD THE
FASTER/AMPLIFIED SIDE OF THE SPREAD BY LATE THU-FRI...WHILE IN
VARYING WAYS THE 00Z GFS/CMC BECOME FAIRLY AMPLIFIED WITH THEIR ERN
NOAM TROUGH ALBEIT WITHIN THE ENSEMBLE SPREAD. THE PREFERRED
ENSEMBLE MEANS TONE DOWN TROUGH AMPLITUDE AND SEWD PROGRESSION OF
THE LEADING COLD FRONT SLIGHTLY.
UPSTREAM DIFFS AT THE SFC BECOME PRONOUNCED BY FRI AS RECENT ECMWF
RUNS HAVE BEEN TRYING TO BRING A WAVE INTO THE UPR MS VLY/UPR GRTLKS
WHILE GFS RUNS KEEP MUCH HIGHER PRESSURES IN PLACE OVER THE REGION.
THE 00Z UKMET HINTS AT AN ECMWF-TYPE WAVE BUT THE 00Z CMC AS WELL AS
LATEST GEFS/ECMWF/CMC MEANS ARE NOT VERY ENTHUSIASTIC ABOUT SUCH A
WAVE. ESPECIALLY GIVEN THE RELATIVELY FLAT NATURE OF THE MEAN FLOW
ALONG THE US-CANADIAN BORDER AT THAT TIME...WOULD PREFER TO SEE MORE
AGREEMENT FROM GUIDANCE BEFORE TRENDING TOWARD THE ECMWF SCENARIO.
THEREFORE LOCALLY...THE CONTINUATION OF BENIGN WEATHER IS EXPECTED
TO MOSTLY PREVAIL WITH MORE SUMMER LIKE TEMPERATURES DURING THE
MIDDLE OF THE WEEK. A FEW LOCATIONS IN METRO NY/NJ MAY REACH THE 90
DEGREE MARK BOTH WED AND THU...WHICH WILL BE THE FIRST TIME IN A
MONTH. HUMIDITY LEVELS WILL ALSO CREEP BACK UP WITH DEWPOINT
TEMPERATURES IN THE MID TO UPPER 60S. HEAT INDICES ARE EXPECTED TO
REMAIN BELOW 95 DEGREES. A PREFRONTAL TROUGH WILL SET UP W OF NYC ON
THU. ISOLD SHOWERS/POSSIBLE A TSTM MAY BE TRIGGERED N AND W OF
NYC...BUT HAVE KEPT THE FORECAST DRY AS PREDICTABILITY IS TOO LOW.
AS THE COLD FRONT WHICH IS PROGGED TO MOVE THROUGH LATE THU
NIGHT/FRI...THE CHC FOR SHOWERS/TSTMS WILL INCREASE ALTHOUGH HAVE
KEPT SCHC POPS AHEAD OF AND WITH ITS PASSAGE DUE TO THE
AFOREMENTIONED UNCERTAINTY. HAVE ALSO GONE WITH THE CONSENSUS NEXT
WEEKEND AND KEPT THE FORECAST DRY.
TEMPS WILL START OFF ABOVE NORMAL...THEN FALL BACK TO SEASONABLE
LEVELS AT THE END OF THE WEEK.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
LOW PRESSURE PASSES TO THE SOUTH TONIGHT. WEAK HIGH PRESSURE
RETURNS ON MONDAY.
VFR THROUGH THE TAF PERIOD. LINGERING LIGHT SHOWERS COME TO AN END
THIS EVENING.
E/NE WINDS BECOME LIGHT AND VARIABLE THIS EVENING...THEN BECOMING
LIGHT WESTERLY AFTER 06Z.
FOR MONDAY...WSW TO SW WINDS INCREASING TO AROUND 10 KT. BKN CIGS OF
AROUND 10-15 KFT LIKELY...WITH SCT 4-6 KFT CU. SEABREEZE DEVELOPMENT
LIKELY ACROSS KJFK/KISP/KBDR/KGON. LOW PROBABILITY OF SEABREEZE
REACHING KLGA...AND NOT EXPECTED ELSEWHERE.
OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY...
.MONDAY NIGHT-WEDNESDAY...VFR.
.THURS...CHC SUB-VFR AND TSTM.
.FRI...VFR.
&&
.MARINE...
SUB SCA CONDITIONS WILL PREVAIL ACROSS THE WATERS THROUGH TUESDAY.
THE PRESSURE GRADIENT WILL REMAIN WEAK ENOUGH TO LIMIT THE UPPER
EXTENT OF WIND SPEED TO AROUND 15 KT AND SEAS ON THE OCEAN WILL
STAY BETWEEN 2 AND 3 FT FOR MOST OF THE TIME. WAVEWATCH GUIDANCE
SEEMED TO BE AGREEING PRETTY WELL WITH CURRENT BUOY OBS IN TERMS
OF WAVE HEIGHT.
THE WINDS AND SEAS ARE FORECAST TO REMAIN BLO SCA LEVELS THROUGH
THE REST OF THE FORECAST PERIOD.
&&
.HYDROLOGY...
NO SIGNIFICANT WIDESPREAD RAIN IS EXPECTED. A FEW HUNDREDTHS OF AN
INCH OF ADDITIONAL QPF IS EXPECTED THIS EVE MAINLY ON EASTERN LONG
ISLAND AND SE CT.
&&
.EQUIPMENT...
THE NOAA ALL HAZARDS WEATHER RADIO TRANSMITTER IN NEW YORK CITY
HAS BEEN DE-ACTIVATED UNTIL FURTHER NOTICE.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...24/JM
NEAR TERM...JM/LN
SHORT TERM...JM
LONG TERM...24
AVIATION...JC
MARINE...24/JM
HYDROLOGY...24/JM
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
759 PM EDT SUN AUG 18 2013
.SYNOPSIS...
LOW PRESSURE WILL TRACK SOUTHEAST OF LONG ISLAND TONIGHT. A
SURFACE TROUGH ACROSS THE AREA ON MONDAY WILL WEAKEN MONDAY NIGHT
AND TUESDAY AS HIGH PRESSURE STARTS TO BUILD IN FROM THE WEST AND
SOUTH. THIS HIGH PRESSURE CENTERED TO OUR SOUTH WILL GRADUALLY
WEAKEN THROUGH THE MIDDLE OF THE WEEK. A COLD FRONT WILL MOVE
THROUGH THE AREA LATE THU NIGHT OR FRI MORNING WITH HIGH PRESSURE
RETURNING IN ITS WAKE.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A WEAK LOW OFF THE DELMARVA COAST WILL CONTINUE TO TRACK
NORTHEAST WHILE DEEPENING A BIT TONIGHT.
RAIN IS MOVING OUT QUICKER THAN EXPECTED...AND IS MAINLY CONFINED
TO LONG ISLAND AND SE CT...SO HAVE ADJUSTED THE POP FORECAST
ACCORDINGLY. RAIN SHOULD BE COMPLETELY OFFSHORE BY 3Z. THE NEXT
THING THAT WILL BEAR WATCHING IS AN AREA OF CONVECTION CURRENTLY
OVER SOUTHERN W VA...ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE. THE
NAM/GFS AND HRRR ALL INDICATE THIS APPROACHES LATE TONIGHT...BUT
KEEP ANY MEASURABLE PRECIP TO OUR W (THE HRRR ENDS AT 11Z WITH IT
OVER ERN PA)
CLOUDS WILL DECREASE OVERNIGHT BUT HOW MUCH REMAINS QUESTIONABLE
DUE TO THE APPROACHING SHORTWAVE ENERGY/PRECIP. AS A
RESULT...RADIATIONAL COOLING MAY BE MORE LIMITED THAN PREVIOUSLY
THOUGHT.
LOWS ARE EXPECTED TO RANGE MOSTLY FROM THE LOWER 50S TO LOWER
60S...A FEW DEGREES WARMER IN THE NEW YORK CITY METRO
AREA...ALTHOUGH MINS MAY NEED TO BE RAISED A FEW DEGREES IF THERE
ENDS UP BEING MORE CLOUD COVER. WILL MONITOR AND REEVALUATE WITH
THE NEXT UPDATE.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
FOR MONDAY...EXPECTING CONSIDERABLE MID AND UPPER LEVEL CLOUDS
AHEAD OF THE NEXT SHORTWAVE. THIS WILL MITIGATE DAYTIME WARMTH BUT
THE GREATER WESTERLY LOW LEVEL FLOW WILL ENABLE BETTER ADIABATIC
MIXING UP TO AROUND 900MB. IT WILL BE WARMEST ACROSS THE URBAN AND
VALLEY CORRIDORS AND A FEW DEGREES COOLER AT THE COAST WITH MORE
ONSHORE FLOW.
THE UPPER LEVEL JET MOVES ACROSS THE REGION WITH ITS ENTRANCE REGION
MOVING ACROSS LATE IN THE DAY INTO THE EVENING. WE ARE NOT NEAR THE
FAVORABLE RIGHT ENTRANCE REGION OF THIS JET BUT CONSIDERING THE
STRONGER SHORTWAVE AND ADDITION OF DAYTIME INSTABILITY...A SHOWER OR
THUNDERSTORM CANNOT BE RULED OUT. IN ADDITION...THE INDICATION OF
DAYTIME SURFACE TROUGH DEVELOPMENT COULD MEAN THAT WINDS COULD BE
MORE WEST OR NORTHWEST AWAY FROM THE COAST WITH MORE SOUTHERLY FLOW
AT THE COAST WITH SEA BREEZE POTENTIAL...THEREBY INCREASING THE
POTENTIAL FOR SURFACE CONVERGENCE.
FOR MONDAY NIGHT...THE UPPER LEVEL JET AND SHORTWAVE AXIS EXIT
SOUTHEAST OF THE REGION. THIS WILL ALLOW FOR HEIGHT RISES ALOFT
AND SURFACE HIGH PRESSURE WILL START TO BUILD IN FROM THE SOUTH
AND WEST. THIS WILL ALSO MARK A MODERATION OF THE AIRMASS TO ONE
MORE TYPICAL OF SUMMER AS TEMPS ALOFT INCREASE SLIGHTLY WITH THE
RIDGING. SO DESPITE THE LOWERING CLOUDS AND LIGHT WINDS...THE LOWS
WILL ACTUALLY BE A FEW DEGREES WARMER THAN THE PREVIOUS NIGHT.
FOR TUESDAY...A CONTINUED WARMING TREND WITH 850MB TEMPS
INCREASING 1-2 DEGREES C FROM THE DAY BEFORE WITH THE ADDED
SUPPORT OF CONTINUED SUBSIDENCE...ALLOWING FOR MORE SUNSHINE.
WINDS WILL BE SIMILAR TO THE DAY BEFORE BUT A FEW KNOTS LIGHTER IN
SPEED.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
LATEST MODELS/ENSEMBLES CONTINUE TO ADVERTISE A GRADUAL
AMPLIFICATION OF THE PATTERN DURING THE MEDIUM RANGE PERIOD...
WITH TROUGHS SETTLING OVER THE ERN PACIFIC AND CANADIAN
MARITIMES/EXTREME WRN ATLC. AT THE SAME TIME A MEAN RIDGE SHOULD
DRIFT SLOWLY EWD FROM THE PLAINS/SRN ROCKIES WHILE ANOTHER RIDGE
SHOULD REMAIN CENTERED OFF THE SERN COAST TO THE N OF THE BAHAMAS.
ALTHOUGH THERE IS GOOD AGREEMENT/CONTINUITY WITH THE FCST FOR
LARGE SCALE FLOW...SPREAD WITH THE TIMING AND AMPLITUDE OF
INDIVIDUAL SHRTWVS WITHIN THE FLOW FROM THE ERN PAC ACROSS SRN
CANADA/NRN TIER CONUS PRESENTS PROBLEMS FOR DETERMINING THE EXACT
POSITION OF THE MEAN SFC BOUNDARY EXPECTED TO SET UP FROM THE NRN
PLAINS INTO THE MID ATLC. SUCH DETAILS ARE TYPICALLY NOT EASILY
RESOLVED IN THE MEDIUM RANGE TIME FRAME SO HAVE LEANED TOWARDS WPC
GUIDANCE WHICH CONSISTS OF A BLEND OF THE 06Z GEFS/00Z ECMWF MEANS
WITH MINOR DETAIL ENHANCEMENTS. THIS SOLN PROVIDES BETTER
CONTINUITY THAN MOST OPERATIONAL MODELS AT THIS TIME.
WITH LEADING HGT FALLS CROSSING THE ERN HALF OF SRN CANADA DURING
THE FIRST HALF OF THE PERIOD THE 00Z ECMWF STARTS LEANING TOWARD THE
FASTER/AMPLIFIED SIDE OF THE SPREAD BY LATE THU-FRI...WHILE IN
VARYING WAYS THE 00Z GFS/CMC BECOME FAIRLY AMPLIFIED WITH THEIR ERN
NOAM TROUGH ALBEIT WITHIN THE ENSEMBLE SPREAD. THE PREFERRED
ENSEMBLE MEANS TONE DOWN TROUGH AMPLITUDE AND SEWD PROGRESSION OF
THE LEADING COLD FRONT SLIGHTLY.
UPSTREAM DIFFS AT THE SFC BECOME PRONOUNCED BY FRI AS RECENT ECMWF
RUNS HAVE BEEN TRYING TO BRING A WAVE INTO THE UPR MS VLY/UPR GRTLKS
WHILE GFS RUNS KEEP MUCH HIGHER PRESSURES IN PLACE OVER THE REGION.
THE 00Z UKMET HINTS AT AN ECMWF-TYPE WAVE BUT THE 00Z CMC AS WELL AS
LATEST GEFS/ECMWF/CMC MEANS ARE NOT VERY ENTHUSIASTIC ABOUT SUCH A
WAVE. ESPECIALLY GIVEN THE RELATIVELY FLAT NATURE OF THE MEAN FLOW
ALONG THE US-CANADIAN BORDER AT THAT TIME...WOULD PREFER TO SEE MORE
AGREEMENT FROM GUIDANCE BEFORE TRENDING TOWARD THE ECMWF SCENARIO.
THEREFORE LOCALLY...THE CONTINUATION OF BENIGN WEATHER IS EXPECTED
TO MOSTLY PREVAIL WITH MORE SUMMER LIKE TEMPERATURES DURING THE
MIDDLE OF THE WEEK. A FEW LOCATIONS IN METRO NY/NJ MAY REACH THE 90
DEGREE MARK BOTH WED AND THU...WHICH WILL BE THE FIRST TIME IN A
MONTH. HUMIDITY LEVELS WILL ALSO CREEP BACK UP WITH DEWPOINT
TEMPERATURES IN THE MID TO UPPER 60S. HEAT INDICES ARE EXPECTED TO
REMAIN BELOW 95 DEGREES. A PREFRONTAL TROUGH WILL SET UP W OF NYC ON
THU. ISOLD SHOWERS/POSSIBLE A TSTM MAY BE TRIGGERED N AND W OF
NYC...BUT HAVE KEPT THE FORECAST DRY AS PREDICTABILITY IS TOO LOW.
AS THE COLD FRONT WHICH IS PROGGED TO MOVE THROUGH LATE THU
NIGHT/FRI...THE CHC FOR SHOWERS/TSTMS WILL INCREASE ALTHOUGH HAVE
KEPT SCHC POPS AHEAD OF AND WITH ITS PASSAGE DUE TO THE
AFOREMENTIONED UNCERTAINTY. HAVE ALSO GONE WITH THE CONSENSUS NEXT
WEEKEND AND KEPT THE FORECAST DRY.
TEMPS WILL START OFF ABOVE NORMAL...THEN FALL BACK TO SEASONABLE
LEVELS AT THE END OF THE WEEK.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
LOW PRESSURE PASSES TO THE SOUTH TONIGHT. WEAK HIGH PRESSURE
RETURNS ON MONDAY.
VFR THROUGH THE TAF PERIOD. LINGERING LIGHT SHOWERS COME TO AN END
THIS EVENING.
E/NE WINDS BECOME LIGHT AND VARIABLE THIS EVENING...THEN BECOMING
LIGHT WESTERLY AFTER 06Z.
FOR MONDAY...WSW TO SW WINDS INCREASING TO AROUND 10 KT. BKN CIGS OF
AROUND 10-15 KFT LIKELY...WITH SCT 4-6 KFT CU. SEABREEZE DEVELOPMENT
LIKELY ACROSS KJFK/KISP/KBDR/KGON. LOW PROBABILITY OF SEABREEZE
REACHING KLGA...AND NOT EXPECTED ELSEWHERE.
OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY...
.MONDAY NIGHT-WEDNESDAY...VFR.
.THURS...CHC SUB-VFR AND TSTM.
.FRI...VFR.
&&
.MARINE...
SUB SCA CONDITIONS WILL PREVAIL ACROSS THE WATERS THROUGH TUESDAY.
THE PRESSURE GRADIENT WILL REMAIN WEAK ENOUGH TO LIMIT THE UPPER
EXTENT OF WIND SPEED TO AROUND 15 KT AND SEAS ON THE OCEAN WILL
STAY BETWEEN 2 AND 3 FT FOR MOST OF THE TIME. WAVEWATCH GUIDANCE
SEEMED TO BE AGREEING PRETTY WELL WITH CURRENT BUOY OBS IN TERMS
OF WAVE HEIGHT.
THE WINDS AND SEAS ARE FORECAST TO REMAIN BLO SCA LEVELS THROUGH
THE REST OF THE FORECAST PERIOD.
&&
.HYDROLOGY...
NO SIGNIFICANT WIDESPREAD RAIN IS EXPECTED. A FEW HUNDREDTHS OF AN
INCH OF ADDITIONAL QPF IS EXPECTED THIS EVE MAINLY ON EASTERN LONG
ISLAND AND SE CT.
&&
.EQUIPMENT...
THE NOAA ALL HAZARDS WEATHER RADIO TRANSMITTER IN NEW YORK CITY
HAS BEEN DE-ACTIVATED UNTIL FURTHER NOTICE.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
351 PM EDT SAT AUG 17 2013
.DISCUSSION...
THROUGH TONIGHT...EAST COAST SEA BREEZE WILL SPARK SCATTERED
STORMS OVER THE INTERIOR AND VOLUSIA NEXT FEW HOURS...THEN STORMS
SHOULD PUSH DIMINISH SHORTLY AFTER SUNSET. SUBSIDENCE ASSOCD WITH SEA
BREEZE CIRCULATION WILL KEEP COASTAL SECTIONS FROM BREVARD TO
MARTIN COUNTIES DRY THE REST OF THE AFTERNOON. THE LOW LEVEL RIDGE
WILL LIFT NORTH OF THE AREA TONIGHT AND PRODUCE A SYNOPTIC E/SE
FLOW OF 10-14 KNOTS. THIS SHOULD BE SUFFICIENT FLOW COMBINED WITH
HIGH MOISTURE TO PRODUCE A FEW ATLC SHOWERS THAT COULD REACH THE
COAST OVERNIGHT SO HAVE DRAWN A 20 POP ALONG THE COAST. A WARM
NIGHT WITH LOWS IN THE MID TO UPPER 70S...EVEN SOME LOWER 80S
BEACHSIDE.
SUN-MON...(PREVIOUS)
CENTRAL FL WILL UNDERGO A SHIFT TO A DRIER WX PATTERN AS THE LIFTING
H30-H20 JET OVER THE APPALACHIANS ALLOWS THE ATLC RIDGE AXIS TO
REPOSITION ITSELF OVER THE DEEP SOUTH BY DAYBREAK SUN. POSITION WILL
BE STABLE AS UPSTREAM JET ENERGY OVER THE SRN TIER STATES IS QUITE
WEAK AND WILL NOT BE ABLE DO DISLODGE IT.
POSITION OF THE RIDGE AXIS WILL GENERATE A DEEP AND STEADY E/SE FLOW
ACRS CENTRAL FL...A PATTERN THAT FAVORS THE WEST PENINSULA FOR
DIURNAL CONVECTION RATHER THAN THE EAST DUE LARGELY TO THE EARLY
FORMATION AND DIFFUSE NATURE OF THE RESULTING EAST COAST SEA BREEZE.
FURTHERMORE...LATEST RUC ANALYSIS SHOWS A NOTEWORTHY DROP IN DEEP
LYR RH APPROACHING THE SRN BAHAMAS THAT WILL WORK ITS WAY INTO THE
FL PENINSULA TO START THE UPCOMING WEEK.
GFS MODEL SOUNDINGS CONFIRM THE ANTICIPATED DRY TREND...DROPPING
PWAT VALUES FROM ARND 2.0" AT 12Z SUN TO ARND 1.7" BY 12Z MON. EVEN
THE HIGHER PWAT VALUES ARE SUN ARE SOMEWHAT DECEIVING AS GFS
INDICATES THE MOISTURE WILL BE EVENLY DISTRIBUTED THRU THE COLUMN...
NOT CONCENTRATED IN THE LOW/MID LVLS WHERE IT WOULD SUPPORT HIGHER
AMOUNTS OF DIURNAL CONVECTION.
STORM POTENTIAL WILL REMAIN LOW AS THE ERLY FLOW TAPS AN AIRMASS
WITH NEGLIGIBLE MID LVL VORTICITY OR OF UPR LVL JET SUPPORT.
THERMODYNAMIC PROFILE MAY PROVIDE SOME PUNCH AS UPSTREAM H50 TEMPS
DROP INTO THE -7C TO -8C RANGE AND H85-H50 LAPSE RATES STEEPEN TO
6.0-6.5C/KM. HOWEVER...ANY STRONG ACTIVITY WOULD TEND TO FORM W OF
THE FL TURNPIKE AS THE DEEP ERLY FLOW WILL PUSH THE SEA BREEZE
RAPIDLY INLAND.
PRECIP COVERAGE AOB 40PCT WITH HIGHEST COVERAGE OVER THE INTERIOR
SUN AFTN TO GIVE A NOD TO THE AFOREMENTIONED HIGHER PWAT VALUES.
ONSHORE FLOW WILL KEEP MAX TEMPS IN THE U80S/L90 ALONG THE COAST...
INTERIOR WARMING TO THE L/M90S. MIN TEMPS L/M70S.
TUE-FRI...
LITTLE CHANGE TO THE CURRENT PHILOSOPHY...STABLE POSITION OF THE
ATLC RIDGE AXIS WILL MAINTAIN A DEEP ERLY FLOW ACRS CENTRAL FL FOR
MUCH OF THE WEEK THAT WILL FOCUS DIURNAL CONVECTION OVER THE W
PENINSULA. POPS 30-40PCT...HIGHER OVER THE INTERIOR DUE TO THE EARLY
FORMATION OF THE EAST COAST SEA BREEZE. MAX TEMPS WITHIN A DEG OR
TWO OF CLIMO AVG...MIN TEMPS 3-5F ABV AVG DUE TO THE PERSISTENT
ONSHORE FLOW.
&&
.AVIATION...
SCT TSRA AT LEE/MCO/SFB THROUGH 23Z. ISOLD SHRA MAY APPROACH
COASTAL TAFS OVERNIGHT BUT COVERAGE DOES NOT WARRANT MENTION IN
TAFS. COULD SEE TEMPO MVFR CIGS 13Z-16Z SUN ALONG WITH ISOLD SHRA
AS DIFFUSE SEA BREEZE DEVELOPS...FOLLOWED BY SCATTERED SHRA/TSRA
FOCUSED ON THE INTERIOR AFT 16Z.
&&
.MARINE...
ATLC RIDGE WILL REPOSITION ITSELF NORTH OF THE WATERS TONIGHT WHERE
IT WILL REMAIN THRU MIDWEEK. THIS RIDGE POSITION WILL GENERATE A
STEADY STATE GENTLE TO MODERATE E/SE BREEZE. THESE WINDS WILL PUSH
A SMALL ERLY SWELL INTO THE LCL ATLC...BUILDING SEAS UP TO 4 FT
OFFSHORE SUN NIGHT AND MONDAY...3 FT NEARSHORE. SEAS WILL
GRADUALLY SUBSIDE TUE-WED AS THE SWELL DAMPENS. ISOLD SHRA/TSRA
THRU THE PD.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 76 89 77 90 / 20 40 20 30
MCO 76 93 75 93 / 20 40 10 30
MLB 78 90 78 91 / 20 30 20 30
VRB 77 91 76 90 / 20 20 20 30
LEE 76 94 76 94 / 20 50 20 40
SFB 77 93 76 93 / 20 40 10 30
ORL 77 93 77 93 / 20 40 10 30
FPR 76 90 76 90 / 20 20 20 30
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
PUBLIC/MARINE/FIRE WX/AVIATION...KELLY
IMPACT WX/RADAR...WEITLICH
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
320 PM EDT Sat Aug 17 2013
.NEAR TERM [This Evening and Tonight]...
A broken band of heavy rain showers and even a few thunderstorms
continues to slowly shift east with time this afternoon across the
forecast area (and our Florida zones in particular). The stronger
convective cells appear to be situated along a composite outflow
boundary / quasi-stationary front, with trailing light-moderate
stratiform rain behind that (encompassing much of the western half
of our forecast area). Therefore, high PoPs were maintained
through the evening hours, particularly in the western two-thirds
of our area. The high-resolution guidance including recent runs of
the HRRR and our local TAE-WRF appears to be doing a poor job
representing ongoing conditions. They dissipate the convection far
too fast and have generally dry conditions advertised over our
area around 19-20 UTC. Therefore, we expect that the ongoing rain
and storms will linger for at least another few hours. The
guidance (including global models) indicates that the rain and
storms will consolidate back to the west later this evening and
tonight. Therefore, the Flash Flood Watch was kept as is - which
expires for our GA and eastern FL zones at 03 UTC, with much of
the heavy rainfall after that time expected west of those areas.
This will have to be closely monitored this evening, though. Given
the environment (high PWATs, efficient rain processes), the threat
of flash flooding continues across the area wherever heavier rain
bands can set up.
&&
.SHORT TERM [Sunday through Monday Night]...
The quasi-stationary front may begin to slowly shift a bit further
west on Sunday and lose its character as a low-level ridge builds
into the Southeast from the Atlantic Ocean. Therefore, there
should be less of a large-scale focusing mechanism for convection
tomorrow (or it should be situated just north and west of our
area). However, guidance still shows relatively high PoPs with
continued high PWAT environment and southerly low-level flow.
Therefore, we maintained likely PoPs over much of the area. A
similar story exists for Monday, although with slightly more
uncertainty we opted for high chance (50%) PoPs instead - but it
could end up being another high coverage day for rain. Daytime
temperatures should continue to be a little cooler than normal.
&&
.LONG TERM [Tuesday through Saturday]...
Southeast low-level flow gradually backs to more of an easterly
direction as an upper level ridge builds into the region. This
should equate to more suppressed convective activity with time,
and overall PoPs show a decreasing trend through the extended
forecast. However, there should still be daily thunderstorm
chances. Temperatures will be closer to normal, perhaps warming to
slightly above normal by later in the week.
&&
.AVIATION [through 18 UTC Sunday]...
Low CIGS and showers with embedded convection will prevail with
MVFR-IFR conditions expected to continue this evening at ECP, DHN,
and ABY and develop later overnight and tomorrow at TLH and VLD.
Brief periods of LIFR CIGS and vsbys are expected in the heaviest
bouts of rain.
&&
.MARINE...
With some breezy southeast winds being observed over the western
waters at the moment (peak winds to near 20 knots), we have
inserted a SCEC headline through tonight west of AAF. The winds
will be slightly weaker in the eastern half of our coastal zones,
but could still approach 15 knots at times. Winds and seas will
lessen somewhat tomorrow morning, followed by a stretch of
easterly flow with winds around 10 knots and seas 3 feet or less.
&&
.FIRE WEATHER...
Abundant moisture and rainfall will prevent red flag conditions
from being met well into next week.
&&
.HYDROLOGY...
Widespread rain with some heavier bands continues this afternoon
across much of the area. A lot of the rain over the western half
of our area has been due to a band of heavier rain showers and a
few thunderstorms. This band has been producing rain rates of up
to 2-3 inches per hour, but has been showing steady eastward
progression. Therefore, flash flooding issues have been isolated
(so far) to urban areas around Panama City. The rain and storms
should continue into the evening - possibly affecting areas
further to the east - but then will eventually re-consolidate back
to the west after midnight and into tomorrow.
Given the widespread nature of the moderate to heavy rainfall,
many river systems around the area should see notable rises and
increased flows, except for perhaps the far southeast part of our
area in Taylor, Lafayette, and Dixie counties. The rivers, as of a
week ago, were running at lower levels than what we had seen for
most of July, so it has taken a considerable amount of rain to
move some to even a bankfull status. Flooding issues will be
determined by the location of the heaviest rainfall over the next
1-2 days, although a few rivers that may be particularly at risk
include: Choctawhatchee, Shoal, Apalachicola.
The most up to date, specific river forecast information can be
found on the AHPS web page at:
http:/water.weather.gov/ahps2/index.php?wfo=tae.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 72 90 73 91 73 / 60 60 30 50 30
Panama City 76 87 76 88 76 / 60 60 40 50 30
Dothan 71 86 72 89 72 / 70 70 30 50 30
Albany 71 88 72 90 72 / 70 60 30 50 30
Valdosta 71 90 72 91 72 / 60 50 30 50 30
Cross City 73 90 72 91 72 / 40 50 40 40 30
Apalachicola 78 87 77 86 77 / 50 50 40 50 30
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...FLASH FLOOD WATCH until 11 PM EDT this evening for all zones
east of the Apalachicola River.
FLASH FLOOD WATCH through Sunday evening for all zones west
of the Apalachicola River.
GA...FLASH FLOOD WATCH until 11 PM EDT this evening for all zones.
AL...FLASH FLOOD WATCH through Sunday evening for all zones.
GM...None.
&&
$$
Lamers/Moore
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
541 AM EDT Sat Aug 17 2013
...HEAVY RAINFALL AND FLOODING CONCERNS EXPECTED AGAIN TODAY...
.NEAR TERM [Thru TODAY]...
We continue in a very wet and unsettled pattern. During the
overnight hours, shortwave energy moving from the Cntrl/Srn Gulf of
Mex has energized another band of deep tropical moisture (PWATS
2.1-2.2 inches) with training cells and interacted with a stalled
front producing moderate to locally heavy rains across portions
of the local area, especially the Panhandle. This aggravated the
flooding situation which necessitated the issuance of a flood
warning for Jackson and Washington counties. RAP soundings imply
that low level steering flow was switching from SW to more sly
feeding more of this moisture Nwd into our AL/GA counties near the
front yielding rain rates of up to 2-3 inches per hour. By 3 AM
EDT, strong to severe storms began developing across the nearshore
waters and this will soon move over coastal counties. All this
reflected well in HRRR.
The large scale pattern continues to amplify with little change
in last 12 hrs providing all the ingredients necessary today for
a continued widespread heavy rain event further aggravating the
flooding situation. Aloft, ridge over Wrn 1/3d and deep trough
over Ern 2/3rd of Conus with axis down MS Valley. A deep 580DM
low will centered over MO/TN border with a trough axis extending
into the northwestern Gulf of Mex. A potent vortmax over AR/TN
border with 90kt upper jet round the base of the trough placing
the area in the favorable right entrance region. Several small
shortwaves riding down base of trough nudging it ewd. All this
increasing upper lift/diffluence over mainly WRN CWA. At the same
time, weal upper ridging exists over Srn FL and a low/tropical
wave was located in the SW Gulf on Mex (NW of Campeche). The
combination of these features has allowed for sfc-H4 SW
unidirectional flow providing a deep conveyor belt of tropical
moisture spreading Newd across our local area. At the surface,
front remains largely stalled from Srn Walton county Nwwd to
along I-10 into SE GA yielding SWLY flow. However the combination
of diurnal heating plus building H5 ridging across the Wrn Atlc
and FL Peninsula should lift front Nwd thru the day placing more
of area in warm sector. Convergence along this boundary should
continue to serve as the focus for low level lift and where
heaviest rains should occur (AL/GA). Model soundings show area
PWATS in excess of 2 inches.
Flash flooding will remain a serious concern as activity continues
to train over areas which have already received significant
rainfall. As the Gulf system moves further Wwd, guidance places the
highest QPF and highest PoPs over the NW third of our forecast area.
With many of these areas already saturated from a very wet summer,
flash flooding will continue to be closely monitored. Thus the flash
flood watch remains in effect for the entire area but Ern sections
should be dropped this aftn. Will have categorical PoPs for most
of the area with temperatures well below normal. See the hydrology
section of this product for more details on the potential. As far
as strong to severe storms, the existence of a very moist boundary
layer and weak lapse rates argue against these storms, however
with upper trough/jet/vort, cant discount wet microbursts with
gusty to damaging winds best bet. SPC keeps us in 5% severe prob.
Will go with CAT POPS west half and likely POPS east half with heavy
rain in grids. Under cloudy and rain conditions, Max temps to remain
well below normal, from around 80 SE AL to mid to upper 80s SE Big
Bend.
&&
.SHORT TERM [Tonight Through Monday]...
As the Gulf system continues to shift Wwd into Wrn Gulf, expect
corridor of heaviest rain progressively sliding west and out of
our forecast area as Atlc ridge progressively builds NWWD thru
period. However, the continued influence of the trough along the
MS Valley (even thought its deamplifying) and now SW-NE oriented
quasi-stnry front should combine for sct-likely POPs thru the
period. For tonight, the deep layer conveyor belt will diminish
as dry air spreads into Srn periphery of upper low but FL
Panhandle and SE AL will remain in a favorable position to receive
additional rain, possibly moderate to heavy, and thus lingering
flooding concerns. By Sun, the upper low will lift Newd towards OH
River Valley but trough and front will linger while the Gulf
system should be far enough west (S TX or Mex) for little impact.
However, latest guidance indicates that a piece of this feature
will shear Nwd strengthening H85 flow and keeping moisture in at
least our Wrn CWA even with the Atlc subtropical ridge building
Nwwd into our area. By Mon, upper ridge over Wrn Atlc will expand
into local area while front has moved further Nwd and weakened.
We will return to a more seasonal pattern of mainly aftn/eve sct
seabreeze driven convection as max temps return to near climo.
Will go with 60-40% NW-SE POPs tonight, 60-50% on Sun and 50-30% N-S
on Mon. Lows tonight around 70. Highs Sun Mid 80s NW to around 90 SE
rising on Mon to upper 80s NW to lower 90s SE.
&&
.LONG TERM [Monday Night through Friday]...
Upper trough over the Lower Mississippi Valley is forecast to
linger through the first half of next week keeping a moist and
unstable airmass in place over the tri-state area. This will keep
PoPs relatively high through at least Tuesday. By later in the
week, there is more uncertainty in the guidance as to how much
ridging will build back over the region, with the ECMWF keeping
the upper trough in tact and the GFS indicating a stronger ridge.
Being well into the extended, will keep conditions close to climo
as a compromise.
&&
.AVIATION...
[Through 06z Sunday] Low cigs and showers with embedded convection
will prevail with MVFR to IFR conditions expected.
&&
.MARINE...
Winds and seas will be on the increase through the weekend
especially around any convection and especially over the western
waters, as a trough of low pressure lingers to the north and west.
However conditions should remain below exercise caution levels
through Sunday. Winds and seas will diminish early next week.
&&
.FIRE WEATHER...
Abundant moisture and rainfall will prevent red flag conditions from
being met well into next week.
&&
.HYDROLOGY...
Up until this morning, except for the FL Panhandle, showers have been
progressive enough and not training which has kept the flood threat
low. However, this should change today as the heaviest rains of this
wet period are expected with widespread average rainfall amounts of
3 to 5 inches still anticipated mainly Wrn areas. Isolated higher
totals are expected, possibly upward of 5 to 8 inches in some
locations.
River flooding will become an increasing concern by late today
and into next week, especially depending on where the heaviest
rainfall ends up occurring. The current thinking is that much of
the heaviest rains will occur in the lower half of the basins.
Thus, if the latest forecast holds, the Choctawhatchee Basin from
Geneva through Bruce would easily return to minor flood stage late
in the weekend with the potential for moderate flooding from
Caryville southward to Bruce early next week. The Chipola has some
capacity for heavy rainfall, but if rainfall amounts trend higher
than expected, minor flooding would be a possibility at Marianna
and Altha early next week.
Into Southeast Alabama, soils are especially saturated and area
creeks and stream will quickly respond to any significant
rainfall. Minor flooding along the Choctawhatchee and Pea Rivers
could occur quickly in this scenario late this weekend.
In Southern Georgia and the Florida Big Bend, current projections
move the Apalachicola, Flint, and Ochlockonee River systems to
near flood stage with anticipated rainfall, though heavier amounts
would easily lead to minor flooding, especially in the lower
portions of these basins where heavier rains were received in
July.
Lighter rainfall amounts are anticipated further east into the
Withlacoochee and Suwannee River basins and the current
anticipation is for these rivers to remain below flood stage into
next week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 84 71 91 74 91 / 80 60 60 50 50
Panama City 83 75 88 77 86 / 90 60 60 50 50
Dothan 81 70 86 71 88 / 90 60 60 40 50
Albany 82 71 88 73 90 / 90 60 60 30 50
Valdosta 85 70 91 73 91 / 70 60 50 40 50
Cross City 88 73 91 72 91 / 50 40 50 40 50
Apalachicola 85 78 87 79 87 / 80 60 60 50 50
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...FLASH FLOOD WATCH through this evening for Coastal Dixie-
Coastal Franklin-Coastal Jefferson-Coastal Taylor-Coastal
Wakulla-Gadsden-Inland Dixie-Inland Franklin-Inland
Jefferson-Inland Taylor-Inland Wakulla-Lafayette-Leon-
Liberty-Madison.
FLASH FLOOD WATCH through Sunday evening for Calhoun-Central
Walton-Coastal Bay-Coastal Gulf-Holmes-Inland Bay-Inland
Gulf-Inland Walton-Jackson-South Walton-Washington.
GA...FLASH FLOOD WATCH through this evening for Baker-Ben Hill-
Berrien-Brooks-Calhoun-Clay-Colquitt-Cook-Decatur-
Dougherty-Early-Grady-Irwin-Lanier-Lee-Lowndes-Miller-
Mitchell-Quitman-Randolph-Seminole-Terrell-Thomas-Tift-
Turner-Worth.
AL...FLASH FLOOD WATCH through Sunday evening for Coffee-Dale-
Geneva-Henry-Houston.
GM...None.
&&
$$
Hydrology...Block/Godsey
LONG TERM...Camp
AVIATION/FIRE WX...DVD
REST OF DISCUSSION...BLOCK
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
530 AM EDT SAT AUG 17 2013
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN AMPLIFIED UPPER LEVEL
PATTERN IN PLACE OVER THE EASTERN HALF OF THE NATION...HIGHLIGHTED
BY A DEEP TROUGH AXIS ALONG AND JUST EAST OF THE MS VALLEY. CLOSER
TO HOME...WEAK UPPER LEVEL RIDGING EXISTS OVER THE SOUTHERN HALF OF
THE FLORIDA PENINSULA. FLOW BETWEEN THESE TWO FEATURES CONTINUES TO
PUMP UP ABUNDANT AND DEEP TROPICAL MOISTURE ACROSS THE EASTERN GULF
AND OVER THE FL PENINSULA. AT THE SURFACE...A WEAK PRESSURE GRADIENT
IS IN PLACE BETWEEN THE SUBTROPICAL RIDGE AXIS TO OUR EAST AND
NORTHEAST AND A WELL DEFINED SURFACE TROUGH/WEAK LOW ACROSS THE
CENTRAL/WESTERN GULF. THIS SURFACE TROUGH TURNS EAST FROM THE MS
DELTA AREA ALONG THE NE GULF COAST/I-10 CORRIDOR.
LOW LEVEL FOCUS JUST SOUTH OF THIS TROUGH AXIS COMBINED WITH UPPER
LEVEL SUPPORT AHEAD OF THE DIGGING MID/UPPER TROUGH IS FORCING A
LARGE AREA OF CONVECTION THIS MORNING ACROSS THE NE GULF/APALACHEE
BAY. TO BE HONEST...MOST OF THE RELIABLE GUIDANCE MODELS ARE NOT
HANDLING THIS CONVECTIVE BLOWUP WELL AT ALL. THE ONLY MODEL THAT IS
STARTING TO COME IN LINE WITH THIS FEATURE IS THE 3KM HRRR (HIGH
RESOLUTION RAPID REFRESH) DUE TO ITS SOPHISTICATED RADAR
INITIALIZATION METHODS. HAVE UPDATED THE FORECAST OVER THE NORTHERN
MARINE ZONES AND NORTHERN NATURE COAST ZONES TO INCREASE POPS
THROUGH MID-MORNING IN LINE WITH THIS LATEST HRRR FORECAST. LEVY
COUNTY LOOKS TO BE RIGHT ON THE BORDER OF THIS AXIS OF FOCUS FOR
CONVECTION...AND WILL HAVE A FAIRLY TIGHT GRADIENT IN THE RAIN
CHANCES FROM WEST TO EAST ACROSS THE COUNTY. ELSEWHERE...OVER LAND
CONDITIONS ARE RATHER QUIET IN THIS PRE-DAWN HOUR. STARTING TO SEE A
FEW SHOWERS DEVELOPING OVER THE WATER FURTHER SOUTH OFF THE COASTS
OF SARASOTA/CHARLOTTE AND LEE COUNTIES. THESE MORE SCT SHOWERS
SHOULD MAINLY STAY OFFSHORE THROUGH MID-MORNING.
&&
.SHORT TERM (TODAY THROUGH MONDAY)...
TODAY...AS DISCUSSED ABOVE...THE MOST DIFFICULT FORECAST ZONES THIS
MORNING WILL BE NORTH OF TAMPA BAY TOWARD CITRUS/LEVY COUNTY IN
CLOSEST PROXIMITY TO THE LOW LEVEL TROUGH FOCUS AND UPPER LEVEL
SUPPORT. BASED ON RADAR TRENDS AND LATEST HRRR FORECAST...THE
HEAVIEST RAINFALL SHOULD STAY JUST WEST OF LEVY COUNTY AND MOVE UP
THROUGH APALACHEE BAY...HOWEVER CERTAINLY EXPECTING SHOWERS TO BE
MOVING ACROSS THOSE COUNTY IN THE NEXT SEVERAL HOURS...AND HAVE
RAISED POPS FOR THIS AREA. THE HRRR DOES TRANSITION BACK TO
AGREEMENT WITH THE LARGER SCALE GUIDANCE FOR THE SECOND HALF OF THE
DAY AND REPOSITIONS THE HEAVIEST RAINFALL POTENTIAL BACK TOWARD THE
FL PANHANDLE. FURTHER SOUTH UNDER INCREASING INFLUENCE OF THE UPPER
RIDGE...THE FORECAST WILL TRANSITION TO ONE MORE REPRESENTATIVE OF A
MID AUGUST DAY. WEAK RIDGING IS IN PLACE BUT CERTAINLY IS NOT ENOUGH
TO SIGNIFICANTLY SUPPRESS CONVECTION. WITH A LIGHT SOUTHEAST LOW
LEVEL FLOW...WILL FOLLOW A RAINFALL FORECAST CONSISTENT WITH
PREFERRED ENHANCEMENT ALONG THE WEST COAST SEA-BREEZE. THIS PATTERN
GENERALLY FEATURES THE EARLIEST CONVECTION IN THE AFTERNOON BREAKING
OUT / MOVING INTO THE SOUTHERN /SOUTH-CENTRAL ZONES...AND THEN
RIPPLING NORTHWARD ALONG THE I-75 CORRIDOR TOWARD THE TAMPA BAY AREA
BY LATE AFTERNOON/EARLY EVENING. WE HAVE BEEN TRICKED THE PAST FEW
DAYS WITH A PATTERN THAT SHOULD HAVE SUPPORTED ABUNDANT DIURNAL
SHOWER ACTIVITY...AND COVERAGE HAS BEEN LESS THAN EXPECTED. ONCE
AGAIN...TODAY LOOKS AS IF THERE IS NOT MUCH TO HOLD BACK THE STORMS
DURING THE AFTERNOON. MID-LEVEL LAPSE RATES ARE NOT GREAT...BUT THIS
SHOULD HAVE MORE INFLUENCE HOLDING BACK STORM INTENSITY RATHER THAN
COVERAGE. ONLY OTHER CONCERN WOULD BE IF ENOUGH MID/HIGH LEVEL
CLOUDS HOLD ON TO KEEP ANY DEFINED SEA-BREEZE FROM FORMING. THIS
WOULD LESSEN THE OVERALL LATE DAY CONVERGENCE AND RESULTING
THUNDERSTORM COVERAGE. IT IS DIFFICULT AND RISKY TO PREDICT THAT NO
SEABREEZE WILL FORM THIS TIME OF YEAR...ESPECIALLY WITH LESS THAN 15
KNOTS OF BOUNDARY LAYER FLOW...WHICH IS USUALLY WHAT IT TAKES TO
START PREVENTING INLAND PENETRATION. WE SHALL SEE...BUT ITS HARD
BASED ON THE ENVIRONMENT NOT TO FORECAST AN ACTIVE (50-60%)
AFTERNOON/EVENING OF STORMS.
TONIGHT...EVENING STORMS ALONG THE I-75 CORRIDOR SHOULD PUSH
OFFSHORE...BUT MAY LINGER FOR AT LEAST A FEW HOURS AFTER
SUNSET...DEPENDING ON JUST HOW LATE IN THE DAY CONVECTION FIRES. IT
DOES LOOK LIKE BY MIDNIGHT MOST IF NOT ALL THE ACTIVITY WILL HAVE
TRANSITIONED OFFSHORE AND LEAVE MOST OF OUR LAND ZONES WITH A QUIET
OVERNIGHT PERIOD.
SUNDAY/MONDAY...UPPER PATTERN WILL DEAMPLIFY WITH TIME INTO THE
EARLY PORTION OF NEXT WEEK ALLOWING THE UPPER RIDGE TO BUILD NORTH
OVER THE ENTIRE FL PENINSULA. AT THE SAME TIME...THE SURFACE RIDGE
WILL ALSO SHIFT FURTHER NORTH KEEPING OUR AREA IN A STEADY EASTERLY
FLOW PATTERN. THE FORECAST FOR SUNDAY AND MONDAY WILL BE SIMILAR DUE
TO THE SIMILAR SYNOPTIC PATTERNS AND FEATURE GENERALLY QUIET MORNING
HOURS GIVING WAY TO INCREASING CHANCES FOR MAINLY LATE DAY/EVENING
STORMS. THE EASTERLY FLOW HAS BEEN A RECURRING THEME THIS SUMMER AND
IS ONE OF OUR MORE ACTIVE PATTERNS FOR THUNDERSTORMS. BOTH DAYS WILL
FEATURE ABOVE CLIMO POPS OF 50-60% FOR THESE STORMS. IT IS IMPORTANT
TO NOTE THAT NEITHER SUNDAY OR MONDAY WILL BE A WASHOUT AS MOST OF
THESE DAYS WILL BE DRY...HOWEVER THE CHANCES ARE JUST ON THE HIGHER
SIDE THAT THE PREDICTED THUNDERSTORM COVERAGE WILL PROVIDE A BRIEF
DOWNPOUR AT MANY LOCATIONS.
&&
.LONG TERM (TUESDAY THROUGH FRIDAY)...
AN U/L RIDGE OVER THE WESTERN ATLANTIC WILL HOLD ACROSS FLORIDA
TUESDAY...AND WILL WEAKEN WEDNESDAY AND THURSDAY AS A WEAK U/L
TROUGH SINKS OVER THE SOUTHEAST U.S. AND PERSISTS INTO FRIDAY WITH
SLIGHTLY LOWER HEIGHTS OVER THE FLORIDA PENINSULA. A STRONG U/L
RIDGE OVER THE SOUTHERN PLAINS WILL BEGIN TO PUSH EAST SATURDAY AND
WILL BUILD OVER WEST CENTRAL AND SOUTHWEST FLORIDA THROUGH THE
WEEKEND. AT THE SURFACE...HIGH PRESSURE OVER THE MID ATLANTIC
COAST WILL PRODUCE EASTERLY BOUNDARY LAYER FLOW ACROSS THE FLORIDA
PENINSULA THROUGH THE PERIOD. TYPICAL SUMMERTIME PATTERN EACH DAY
WITH THE WEST COAST SEA BREEZE BEING HELD OVER THE COASTAL COUNTIES
OF WEST CENTRAL AND SOUTHWEST FLORIDA...WITH THE EAST COAST SEA
BREEZE MOVING ACROSS THE PENINSULA AND COLLIDING WITH THE WEST COAST
SEA BREEZE DURING THE LATE AFTERNOON/EARLY EVENING EACH DAY.
SCATTERED TO NUMEROUS AFTERNOON THUNDERSTORMS EACH DAY WITH THE
HIGHEST POPS OVER THE COASTAL COUNTIES. BOUNDARY LAYER WINDS MAY
WEAKEN A BIT FRIDAY AND SATURDAY WHICH WOULD ALLOW THE WEST COAST
SEA BREEZE TO PUSH SLIGHTLY FURTHER INLAND. STRONG CONVERGENCE
ALONG THE WEST COAST SEA BREEZE BOUNDARY COMBINED WITH STRONG
DAYTIME HEATING MAY ALLOW AN ISOLATED PULSE SEVERE THUNDERSTORM TO
DEVELOP EACH AFTERNOON. TEMPERATURES WILL RUN A FEW DEGREES ABOVE
CLIMATIC NORMALS EACH DAY.
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL THROUGH EARLY THIS MORNING. SCT LCL BKN
020-030 WILL DEVELOP MID TO LATE MORNING LIFTING TO 030-035 THIS
AFTERNOON. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS VCNTY
ALL TERMINALS THIS AFTERNOON...WITH LCL MVFR CIGS AND IFR VSBYS.
&&
.MARINE...
THE FORECAST WATERS WILL RESIDE WITHIN A ZONE OF SOUTHEAST FLOW
BETWEEN THE SUBTROPICAL RIDGE AXIS TO OUR EAST AND NORTHEAST AND A
WEAK AREA OF LOW PRESSURE AND SURFACE TROUGH OVER THE CENTRAL GULF
OF MEXICO. BY THE EARLY PORTION OF NEXT WEEK...THE RIDGE AXIS WILL
MOVE EVEN FURTHER NORTH AND PLACE OUR REGION IN A ZONE OF MORE
CONSISTENT EASTERLY FLOW.
&&
.FIRE WEATHER...
TYPICAL SUMMER CONDITIONS ARE IN THE FORECAST
THROUGH THE WEEKEND. EASTERLY FLOW WILL RESULT IN AN ACTIVE
AFTERNOON AND EVENING THUNDERSTORM PATTERN THROUGH THE NEXT
SEVERAL DAYS. RELATIVE HUMIDITY VALUES ARE EXPECTED TO REMAIN WELL
ABOVE CRITICAL LEVELS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 92 79 92 78 / 50 40 50 40
FMY 93 77 93 77 / 60 30 50 30
GIF 94 75 93 75 / 50 30 50 20
SRQ 92 78 93 77 / 50 40 50 40
BKV 93 74 92 75 / 60 40 50 30
SPG 93 80 91 79 / 50 40 50 40
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...OGLESBY
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
351 AM EDT SAT AUG 17 2013
.DISCUSSION...
ATLC RIDGE AXIS CURRENTLY OVER CENTRAL FL WL TRANSITION NORTH OF
THE AREA DURING THE DAY...OPENING UP AN ONSHORE FLOW PATTERN THAT
WILL PERSIST WELL INTO NEXT WEEK. AMPLE MOISTURE REMAINS ACROSS
THE REGION WITH PWAT INVOF 2 INCHES. THE EARLY ONGOING SHRA AND
ISOLD TS ALONG THE INTERIOR AND WEST COAST APPEARS ASCD WITH
FORCED ASCENT ASCD WITH AN UPSTREAM WAVE ALONG THE NRN GULF
COAST. TODAYS FORECAST WL FAVOR INTERIOR FOR BEST RAIN CHCS DUE TO
DEEPENING ONSHORE PATTERN AND BEST BOUNDARY INTERACTION POTENTIAL.
MARGINAL INSTABILITY SHOULD BE AIDED BY PREVIOUSLY MENTIONED
UPSTREAM WAVE AND MID RANGE SCT COVERAGE OF STORMS CAN BE EXPECTED
INLAND TAPERING BACK TO ISOLD ALONG THE SPACE COAST SWD TO LAKE
OKEE AND THE TREASURE COAST...WHERE MARINE SOURCE PCPN MAY BE THE
MAIN MECHANISM FOR ANY MEASURABLE PRECIP. EXPECT HIGHS IN THE
LOWER TO MID 90S INLAND AND AROUND 90 AT THE COAST.
AS DUSK APPROACHES PRECIP POTENTIAL WL DIMINISH AND EVENTUALLY
TRANSITION TO THE COAST WHERE ONSHORE MOVING SHOWERS WL AFFECT
SOME AREAS INTO EARLY SUN. HIGHEST CHCS WL BE ALONG S CST WHERE
MOST FAVORABLE ONSHORE TRAJECTORY WL EXIST.
SUN-MON...
CENTRAL FL WILL UNDERGO A SHIFT TO A DRIER WX PATTERN AS THE LIFTING
H30-H20 JET OVER THE APPALACHIANS ALLOWS THE ATLC RIDGE AXIS TO
REPOSITION ITSELF OVER THE DEEP SOUTH BY DAYBREAK SUN. POSITION WILL
BE STABLE AS UPSTREAM JET ENERGY OVER THE SRN TIER STATES IS QUITE
WEAK AND WILL NOT BE ABLE DO DISLODGE IT.
POSITION OF THE RIDGE AXIS WILL GENERATE A DEEP AND STEADY E/SE FLOW
ACRS CENTRAL FL...A PATTERN THAT FAVORS THE WEST PENINSULA FOR
DIURNAL CONVECTION RATHER THAN THE EAST DUE LARGELY TO THE EARLY
FORMATION AND DIFFUSE NATURE OF THE RESULTING EAST COAST SEA BREEZE.
FURTHERMORE...LATEST RUC ANALYSIS SHOWS A NOTEWORTHY DROP IN DEEP
LYR RH APPROACHING THE SRN BAHAMAS THAT WILL WORK ITS WAY INTO THE
FL PENINSULA TO START THE UPCOMING WEEK.
GFS MODEL SOUNDINGS CONFIRM THE ANTICIPATED DRY TREND...DROPPING
PWAT VALUES FROM ARND 2.0" AT 12Z SUN TO ARND 1.7" BY 12Z MON. EVEN
THE HIGHER PWAT VALUES ARE SUN ARE SOMEWHAT DECEIVING AS GFS
INDICATES THE MOISTURE WILL BE EVENLY DISTRIBUTED THRU THE COLUMN...
NOT CONCENTRATED IN THE LOW/MID LVLS WHERE IT WOULD SUPPORT HIGHER
AMOUNTS OF DIURNAL CONVECTION.
STORM POTENTIAL WILL REMAIN LOW AS THE ERLY FLOW TAPS AN AIRMASS
WITH NEGLIGIBLE MID LVL VORTICITY OR OF UPR LVL JET SUPPORT.
THERMODYNAMIC PROFILE MAY PROVIDE SOME PUNCH AS UPSTREAM H50 TEMPS
DROP INTO THE -7C TO -8C RANGE AND H85-H50 LAPSE RATES STEEPEN TO
6.0-6.5C/KM. HOWEVER...ANY STRONG ACTIVITY WOULD TEND TO FORM W OF
THE FL TURNPIKE AS THE DEEP ERLY FLOW WILL PUSH THE SEA BREEZE
RAPIDLY INLAND.
PRECIP COVERAGE AOB 40PCT WITH HIGHEST COVERAGE OVER THE INTERIOR
SUN AFTN TO GIVE A NOD TO THE AFOREMENTIONED HIGHER PWAT VALUES.
ONSHORE FLOW WILL KEEP MAX TEMPS IN THE U80S/L90 ALONG THE COAST...
INTERIOR WARMING TO THE L/M90S. MIN TEMPS L/M70S.
TUE-FRI...
LITTLE CHANGE TO THE CURRENT PHILOSOPHY...STABLE POSITION OF THE
ATLC RIDGE AXIS WILL MAINTAIN A DEEP ERLY FLOW ACRS CENTRAL FL FOR
MUCH OF THE WEEK THAT WILL FOCUS DIURNAL CONVECTION OVER THE W
PENINSULA. POPS 30-40PCT...HIGHER OVER THE INTERIOR DUE TO THE EARLY
FORMATION OF THE EAST COAST SEA BREEZE. MAX TEMPS WITHIN A DEG OR
TWO OF CLIMO AVG...MIN TEMPS 3-5F ABV AVG DUE TO THE PERSISTENT
ONSHORE FLOW.
&&
.AVIATION...
ISOLD EARLY SHOWERS WITH ASCD CIGS NR 035-040FT NR ISM-LEE THROUGH
14Z TRANSITION TO ADTL SHOWERS WITH A FEW STORMS MOVING NWD FM
15Z THROUGH 18Z WILL FILL IN ACROSS PRIMARILY INTERIOR SECTIONS
AWAY FROM THE E COAST THE REGION THROUGH MID AFTN. BEST PERIOD FOR
SCT MVFR AND ISOLD IFR CONDS AT TAF SITES WL OCCUR FM 18Z-22Z AND INLAND.
OCNL CIGS FM 025-035 WL OCCUR IN SHOWERS ALONG WITH OCNL-FRQT LTG
AND WND G30-35KT IN ANY STRONGER TS.
&&
.MARINE...
FAVORABLE SEA HGHTS FOR SMALL CRAFT DURIN THE DAY WITH INDICATED SIG
WV CURRENTLY MEASURING 1-2 FT AND LIKELY 2-3 FT OVER THE OUTERMOST
WATERS. SLOWLY INCREASING HGHTS CAN BE EXPECTED INTO TONIGHT WITH
DEVELOPMENT OF ONSHORE GRADIENT WINDS AS HIGH PRESSURE LIFTS NORTH
OF THE REGION.
SUN-WED...ATLC RIDGE WILL REPOSITION ITSELF OVER THE DEEP SOUTH BY
DAYBREAK WHERE IT WILL REMAIN THRU MIDWEEK. RIDGE POSITION WILL
GENERATE A STEADY STATE GENTLE TO MODERATE E/SE BREEZE. THESE WINDS
WILL PUSH A SMALL ERLY SWELL INTO THE LCL ATLC...KEEPING SEAS 3-4FT
THRU MON. SEAS WILL SUBSIDING TO 2-3FT NEARSHORE AND 3-4FT OFFSHORE
TUE THE SWELL DAMPENS. ISOLD SHRAS/ TSRAS THRU THE PD.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 91 76 89 77 / 30 20 30 20
MCO 94 76 93 76 / 40 20 40 20
MLB 92 78 89 79 / 30 30 30 20
VRB 91 77 90 77 / 30 30 30 20
LEE 92 76 93 77 / 40 20 40 20
SFB 94 76 93 77 / 40 20 40 20
ORL 94 77 93 77 / 40 20 40 20
FPR 90 76 90 78 / 30 30 30 20
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM...PENDERGRAST
LONG TERM....BRAGAW
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
339 AM EDT Sat Aug 17 2013
...HEAVY RAINFALL AND FLOODING CONCERNS EXPECTED AGAIN TODAY...
.NEAR TERM [Thru TODAY]...
We continue in a very wet and unsettled pattern. During the
overnight hours, shortwave energy moving from the Cntrl/Srn Gulf of
Mex has energized another band of deep tropical moisture (PWATS
2.1-2.2 inches) with training cells and interacted with a stalled
front producing moderate to locally heavy rains across portions
of the local area, especially the Panhandle. This aggravated the
flooding situation which necessitated the issuance of a flood
warning for Jackson and Washington counties. RAP soundings imply
that low level steering flow was switching from SW to more sly
feeding more of this moisture Nwd into our AL/GA counties near the
front yielding rain rates of up to 2-3 inches per hour. By 3 AM
EDT, strong to severe storms began developing across the nearshore
waters and this will soon move over coastal counties.
The large scale pattern continues to amplify with little change
in last 12 hrs providing all the ingredients necessary today for
a continued widespread heavy rain event further aggravating the
flooding situation. Aloft, ridge over Wrn 1/3d and deep trough
over Ern 2/3rd of Conus with axis down MS Valley. A deep 580DM low
will centered over NE Missouri with a trough axis extending into
the northwestern Gulf of Mex. A potent vortmax over AR/TN border
with 90kt upper jet round the base of the trough placing the area
in the favorable right entrance region. Several small shortwaves
riding down base of trough nudging it ewd. All this increasing
upper lift/diffluence over mainly WRN CWA. At the same time, a
low/tropical wave was located in the SW Gulf on Mex (NW of
Campeche). The combination of these features has allowed for
sfc-H4 SW unidirectional flow providing a deep conveyor belt of
tropical moisture spreading Newd across our local area. At the
surface, front remains largely stalled from Srn Walton county Nwwd
to just south of Marianna/Bainbridge into SE GA yielding SWLY
flow. However the combination of diurnal heating plus building H5
ridging across the Wrn Atlc and FL Peninsula should lift front Nwd
thru the day placing more of area in warm sector. Convergence
along this boundary should continue to serve as the focus for low
level lift and where heaviest rains should occur. Model soundings
show area PWATS in excess of 2 inches.
Flash flooding will remain a serious concern as activity continues
to train over areas which have already received significant
rainfall. As the Gulf system moves further Wwd, guidance places the
highest QPF and highest PoPs over the NW third of our forecast area.
With many of these areas already saturated from a very wet summer,
flash flooding will continue to be closely monitored. Thus the flash
flood watch remains in effect for the entire area but Ern sections
should may be dropped by this aftn. Will have categorical PoPs
for most of the area with temperatures well below normal. See the
hydrology section of this product for more details on the potential.
As far as strong to severe storms, the existence of a very moist
boundary layer and weak lapse rates argue against these storms,
however with upper trough/jet/vort, cant discount wet microbursts
with gusty to damaging winds best bet. SPC keeps us in 5% severe
prob.
Will go with CAT POPS west half and likely POPS east half with heavy
rain in grids. Under cloudy and rain conditions, Max temps to remain
well below normal, from around 80 SE AL to mid to upper 80s SE Big
Bend.
&&
.SHORT TERM [Tonight Through Monday]...
As the Gulf system continues to shift Wwd into Wrn Gulf, expect
heavy rain to decrease from E-W with the corridor of heaviest rain
progressively sliding to west of our forecast area. However, the
continued influence of the trough along the MS Valley (even thought
its deamplifying) and now SW-NE oriented quasi-stnry front should
combine for sct-likely POPs thru the period. For tonight, the deep
layer conveyor belt will diminish but FL Panhandle and SE AL will
remain in a favorable position to receive additional heavy rain and
lingering flooding concerns. By Sun, the upper low will lift newd
towards OH River Valley but trough and front will linger while the
Gulf system should be far enough west for little impact. However,
latest guidance indicates that a piece of this feature will shear
Nwd strengthening H85 flow and keeping moisture in at least our Wrn
CWA even with the Atlc subtropical ridge building Nwwd into our
area. By Mon, upper ridge over Wrn Atlc will build into local area.
We will return to a more seasonal pattern of sct seabreeze driven
convection as POPs decrease and max temps will return to near
climo.
Will go with 60-40% NW-SE POPs tonight, 60-50% on Sun and 50-30% N-S
on Mon. Lows tonight around 70. Highs Sun Mid 80s NW to around 90 SE
rising on Mon to upper 80s NW to lower 90s SE.
&&
.LONG TERM [Monday Night through Friday]...
Upper trough over the Lower Mississippi Valley is forecast to
linger through the first half of next week keeping a moist and
unstable airmass in place over the tri-state area. This will keep
PoPs relatively high through at least Tuesday. By later in the
week, there is more uncertainty in the guidance as to how much
ridging will build back over the region, with the ECMWF keeping
the upper trough in tact and the GFS indicating a stronger ridge.
Being well into the extended, will keep conditions close to climo
as a compromise.
&&
.AVIATION...
[Through 06z Sunday] Low cigs and showers with embedded convection
will prevail with MVFR to IFR conditions expected.
&&
.MARINE...
Winds and seas will be on the increase through the weekend
especially around any convection and especially over the western
waters, as a trough of low pressure lingers to the north and west.
However conditions should remain below exercise caution levels
through Sunday. Winds and seas will diminish early next week.
&&
.FIRE WEATHER...
Abundant moisture and rainfall will prevent red flag conditions from
being met well into next week.
&&
.HYDROLOGY...
Up until this morning, except for the FL Panhandle, showers have been
progressive enough and not training which has kept the flood threat
low. However, this should change today as the heaviest rains of this
wet period are expected with widespread average rainfall amounts of
3 to 5 inches still anticipated mainly Wrn areas. Isolated higher
totals are expected, possibly upward of 5 to 8 inches in some
locations.
River flooding will become an increasing concern by late today
and into next week, especially depending on where the heaviest
rainfall ends up occurring. The current thinking is that much of
the heaviest rains will occur in the lower half of the basins.
Thus, if the latest forecast holds, the Choctawhatchee Basin from
Geneva through Bruce would easily return to minor flood stage late
in the weekend with the potential for moderate flooding from
Caryville southward to Bruce early next week. The Chipola has some
capacity for heavy rainfall, but if rainfall amounts trend higher
than expected, minor flooding would be a possibility at Marianna
and Altha early next week.
Into Southeast Alabama, soils are especially saturated and area
creeks and stream will quickly respond to any significant
rainfall. Minor flooding along the Choctawhatchee and Pea Rivers
could occur quickly in this scenario late this weekend.
In Southern Georgia and the Florida Big Bend, current projections
move the Apalachicola, Flint, and Ochlockonee River systems to
near flood stage with anticipated rainfall, though heavier amounts
would easily lead to minor flooding, especially in the lower
portions of these basins where heavier rains were received in
July.
Lighter rainfall amounts are anticipated further east into the
Withlacoochee and Suwannee River basins and the current
anticipation is for these rivers to remain below flood stage into
next week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 84 71 91 74 91 / 80 60 60 50 50
Panama City 83 75 88 77 86 / 90 60 60 50 50
Dothan 81 70 86 71 88 / 90 60 60 40 50
Albany 82 71 88 73 90 / 90 60 60 30 50
Valdosta 85 70 91 73 91 / 70 60 50 40 50
Cross City 88 73 91 72 91 / 50 40 50 40 50
Apalachicola 85 78 87 79 87 / 80 60 60 50 50
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...FLASH FLOOD WATCH through this evening for Coastal Dixie-
Coastal Franklin-Coastal Jefferson-Coastal Taylor-Coastal
Wakulla-Gadsden-Inland Dixie-Inland Franklin-Inland
Jefferson-Inland Taylor-Inland Wakulla-Lafayette-Leon-
Liberty-Madison.
FLASH FLOOD WATCH through Sunday evening for Calhoun-Central
Walton-Coastal Bay-Coastal Gulf-Holmes-Inland Bay-Inland
Gulf-Inland Walton-Jackson-South Walton-Washington.
GA...FLASH FLOOD WATCH through this evening for Baker-Ben Hill-
Berrien-Brooks-Calhoun-Clay-Colquitt-Cook-Decatur-
Dougherty-Early-Grady-Irwin-Lanier-Lee-Lowndes-Miller-
Mitchell-Quitman-Randolph-Seminole-Terrell-Thomas-Tift-
Turner-Worth.
AL...FLASH FLOOD WATCH through Sunday evening for Coffee-Dale-
Geneva-Henry-Houston.
GM...None.
&&
$$
Hydrology...Block/Godsey
LONG TERM...Camp
AVIATION/FIRE WX...DVD
REST OF DISCUSSION...BLOCK
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
940 PM EDT SUN AUG 18 2013
.UPDATE...
HAVE ADJUSTED POPS FOR A FEW HOURS BASED ON RADAR. SCATTERED
CONVECTION STILL MOSTLY ACROSS CENTRAL ZONES. WEDGE STILL HOLDING
JUST ABOUT ATLANTA TO ATHENS AND MAY NOT MUVE MUCH MORE OVERNIGHT.
WILL KEEP THE FLASH FLOOD WATCH UNTIL EXPIRATION.
41
.PREVIOUS...
.SHORT TERM /TONIGHT THROUGH MONDAY/...
PRIMARY CONCERNS FOR THE SHORT TERM PERIOD WILL BE WHERE MODERATE
TO HEAVY RAIN AXIS SETS UP AND WHAT NEEDS TO BE DONE WITH THE
FLASH FLOOD WATCH AS A RESULT. AFTER A WET START TO THE
DAY...ACTIVITY HAS DWINDLED FOR THE MOST PART WITH JUST SOME
PASSING SHOWERS THROUGH THE ATLANTA METRO NOW HEADING INTO
NORTHEAST GEORGIA. FOCUS NOW SHIFTS TO THE SOUTHEAST WHERE LOCAL
WRF AND HRRR HAVE BEEN BEEN HONING IN ON WITH THUNDERSTORMS
DEVELOPING NICELY OVER THE FAR SOUTHEAST AT THIS HOUR. SPC SREF
SHOWS INSTABILITY INCREASING AS WARM FRONT EASES NORTHWARD WITH
AREAS AROUND TOOMBS AND MONTGOMERY COUNTIES SHOWING IN EXCESS OF
1000 J/KG OF AVAILABLE CAPE. WOULD EXPECT A LINE OF SHOWERS AND
STORMS TO DEVELOP IN THIS AREA AND PROGRESS TOWARD MACON LATER THIS
AFTERNOON INTO THE EVENING. ADDITIONAL ACTIVITY COULD FORM AHEAD
OF THIS AS WELL IN THE MORE UNSTABLE SECTION FROM COLUMBUS TO JUST
SOUTH OF ATHENS.
ALSO WATCHING GULF INITIATED STORMS AS THESE LOOK TO AFFECT THE
SOUTH AS WELL TONIGHT WITH STORMS ALREADY PUSHING INTO THE GEORGIA
PORTION FROM THE FLORIDA PANHANDLE. THERE IS SOME DISPARITY IN
SHORT TERM MODELS ON HOW THIS WILL EVENTUALLY EVOLVE THIS EVENING
WITH NAM12 INDICATING MORE DEVELOPMENT ON THE WESTERN SIDE OF THE
AREA VERSUS THE SOUTH. THIS UNCERTAINTY IS PROBLEMATIC GIVEN THE
FLOOD WATCH ORIENTATION WHICH IS CURRENTLY OVER THE WEST. IF
CURRENT TRENDS HOLD HOWEVER...THE SOUTHERN SECTIONS WOULD BE MORE
UNDER THE GUN. WITH THE UNCERTAINTY INVOLVED...WILL LET THE
EVENING SHIFT TAKE ANOTHER LOOK AT THIS DEVELOPING EVENT TO SEE
IF FLOOD WATCH NEEDS TO CONTINUE AND FOR WHAT AREAS.
FOR MONDAY...PRETTY MUCH THE SAME PATTERN BUT WITH WEDGE
CONTINUING TO WEAKEN AND MORE MOISTURE AVAILABLE FOR THE NORTHERN
ZONES AS WELL AS INSTABILITY. WENT LIKELY FOR MOST
AREAS...FAVORING THE SOUTH ONCE AGAIN...CLOSER TO THE VICINITY OF
STALLED OUT BOUNDARY. STILL USED SOME SLIGHT CAD INFLUENCES FOR
THE HIGH TEMPS MONDAY BUT SHOULD WARM NICELY TO UPPER 70S NORTH TO
LOWER 80S SOUTH.
DEESE
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
BUMPED POPS UP SOME INTO THURSDAY TO ACCOUNT FOR THE VERY MOIST
AIRMASS OVER THE AREA. OTHERWISE NO MAJOR CHANGES.
BDL
PREVIOUS DISCUSSION...
THE WET PATTERN CONTINUES INTO THE EXTENDED. THE STATIONARY FRONT
OVER SOUTH GA TODAY WILL MOVE SLOWLY NORTHWARD THROUGH MONDAY AND
SHOULD BE SOME WHERE BETWEEN ATL AND MCN BY TUE MORNING. THIS FRONT
WILL WEAKEN SOME BUT IT WILL STILL ACT AS A GUIDE FOR GULF MOISTURE
TO MOVE NORTHWARD ACROSS THE REGION THROUGH THE MIDDLE OF THE WEEK.
THE WEDGE LOOKS TO FINALLY BREAK DOWN SOMETIME MONDAY WHICH WILL
ALSO ALLOW FOR A MORE DIURNALLY DRIVEN PRECIP PATTERN THROUGH DAY 7.
BEST TIMING FOR THE HEAVIEST RAIN WILL BE IN THE SHORT TERM BUT DEEP
TROPICAL MOISTURE REMAINS OVER THE REGION THROUGH WED/THU WITH
PRECIPITABLE WATERS IN THE 1.5 TO 2.0 INCH RANGE THROUGH THU. THE
DEEPER MOISTURE MOVES NORTH AND EAST OF THE STATE BY THU NIGHT BUT
THE DIURNAL CONVECTIVE TREND WILL CONTINUE INTO NEXT WEEKEND. TEMPS
WILL BEGIN TO REBOUND BY TUE AND BE BACK TO NEAR SEASONAL NORMS BY
THU/FRI.
01
&&
.AVIATION...
00Z UPDATE...
FRONTAL BOUNDARY JUST SOUTH OF ATL SHOULD REMAIN NEARLY STATIONARY
THROUGH THE NIGHT. LIGHT EAST WINDS WILL PERSIST OVERNIGHT AND
CONTINUE AROUND 10KT AFTER 14Z MONDAY. ALL SITES WILL GO IFR BY LATE
THIS EVENING AND THEN LIFR FOR THE EARLY MORNING HOURS. PREVAILING
SHOWERS CONTINUING WITH SOME SCATTERED THUNDERSTORMS. A FEW STORMS
POSSIBLY SEVERE.
//ATL CONFIDENCE...00Z UPDATE...
MEDIUM ON ALL ELEMENTS
41
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 69 81 69 79 / 50 60 50 70
ATLANTA 69 79 70 79 / 70 50 40 60
BLAIRSVILLE 65 76 66 78 / 70 50 50 60
CARTERSVILLE 69 79 69 78 / 70 50 50 60
COLUMBUS 71 83 72 85 / 50 60 40 70
GAINESVILLE 68 78 69 76 / 70 50 50 70
MACON 70 82 70 82 / 40 60 40 60
ROME 69 80 70 80 / 70 50 50 60
PEACHTREE CITY 70 80 71 79 / 60 50 40 60
VIDALIA 72 86 72 86 / 40 60 40 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING
ZONES: BARTOW...BIBB...BLECKLEY...BUTTS...CARROLL...CATOOSA...
CHATTAHOOCHEE...CHATTOOGA...CHEROKEE...CLAYTON...COBB...COWETA...
CRAWFORD...CRISP...DADE...DEKALB...DODGE...DOOLY...DOUGLAS...
FANNIN...FAYETTE...FLOYD...GILMER...GORDON...HARALSON...HARRIS...
HEARD...HENRY...HOUSTON...LAMAR...MACON...MARION...MERIWETHER...
MONROE...MURRAY...MUSCOGEE...NORTH FULTON...PAULDING...PEACH...
PICKENS...PIKE...POLK...PULASKI...ROCKDALE...SCHLEY...SOUTH
FULTON...SPALDING...STEWART...SUMTER...TALBOT...TAYLOR...
TELFAIR...TROUP...TWIGGS...UPSON...WALKER...WEBSTER...
WHITFIELD...WILCOX.
&&
$$
SHORT TERM...DEESE
LONG TERM....BDL
AVIATION...41
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
800 PM EDT SUN AUG 18 2013
.SHORT TERM /TONIGHT THROUGH MONDAY/...
PRIMARY CONCERNS FOR THE SHORT TERM PERIOD WILL BE WHERE MODERATE
TO HEAVY RAIN AXIS SETS UP AND WHAT NEEDS TO BE DONE WITH THE
FLASH FLOOD WATCH AS A RESULT. AFTER A WET START TO THE
DAY...ACTIVITY HAS DWINDLED FOR THE MOST PART WITH JUST SOME
PASSING SHOWERS THROUGH THE ATLANTA METRO NOW HEADING INTO
NORTHEAST GEORGIA. FOCUS NOW SHIFTS TO THE SOUTHEAST WHERE LOCAL
WRF AND HRRR HAVE BEEN BEEN HONING IN ON WITH THUNDERSTORMS
DEVELOPING NICELY OVER THE FAR SOUTHEAST AT THIS HOUR. SPC SREF
SHOWS INSTABILITY INCREASING AS WARM FRONT EASES NORTHWARD WITH
AREAS AROUND TOOMBS AND MONTGOMERY COUNTIES SHOWING IN EXCESS OF
1000 J/KG OF AVAILABLE CAPE. WOULD EXPECT A LINE OF SHOWERS AND
STORMS TO DEVELOP IN THIS AREA AND PROGRESS TOWARD MACON LATER THIS
AFTERNOON INTO THE EVENING. ADDITIONAL ACTIVITY COULD FORM AHEAD
OF THIS AS WELL IN THE MORE UNSTABLE SECTION FROM COLUMBUS TO JUST
SOUTH OF ATHENS.
ALSO WATCHING GULF INITIATED STORMS AS THESE LOOK TO AFFECT THE
SOUTH AS WELL TONIGHT WITH STORMS ALREADY PUSHING INTO THE GEORGIA
PORTION FROM THE FLORIDA PANHANDLE. THERE IS SOME DISPARITY IN
SHORT TERM MODELS ON HOW THIS WILL EVENTUALLY EVOLVE THIS EVENING
WITH NAM12 INDICATING MORE DEVELOPMENT ON THE WESTERN SIDE OF THE
AREA VERSUS THE SOUTH. THIS UNCERTAINTY IS PROBLEMATIC GIVEN THE
FLOOD WATCH ORIENTATION WHICH IS CURRENTLY OVER THE WEST. IF
CURRENT TRENDS HOLD HOWEVER...THE SOUTHERN SECTIONS WOULD BE MORE
UNDER THE GUN. WITH THE UNCERTAINTY INVOLVED...WILL LET THE
EVENING SHIFT TAKE ANOTHER LOOK AT THIS DEVELOPING EVENT TO SEE
IF FLOOD WATCH NEEDS TO CONTINUE AND FOR WHAT AREAS.
FOR MONDAY...PRETTY MUCH THE SAME PATTERN BUT WITH WEDGE
CONTINUING TO WEAKEN AND MORE MOISTURE AVAILABLE FOR THE NORTHERN
ZONES AS WELL AS INSTABILITY. WENT LIKELY FOR MOST
AREAS...FAVORING THE SOUTH ONCE AGAIN...CLOSER TO THE VICINITY OF
STALLED OUT BOUNDARY. STILL USED SOME SLIGHT CAD INFLUENCES FOR
THE HIGH TEMPS MONDAY BUT SHOULD WARM NICELY TO UPPER 70S NORTH TO
LOWER 80S SOUTH.
DEESE
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
BUMPED POPS UP SOME INTO THURSDAY TO ACCOUNT FOR THE VERY MOIST
AIRMASS OVER THE AREA. OTHERWISE NO MAJOR CHANGES.
BDL
PREVIOUS DISCUSSION...
THE WET PATTERN CONTINUES INTO THE EXTENDED. THE STATIONARY FRONT
OVER SOUTH GA TODAY WILL MOVE SLOWLY NORTHWARD THROUGH MONDAY AND
SHOULD BE SOME WHERE BETWEEN ATL AND MCN BY TUE MORNING. THIS FRONT
WILL WEAKEN SOME BUT IT WILL STILL ACT AS A GUIDE FOR GULF MOISTURE
TO MOVE NORTHWARD ACROSS THE REGION THROUGH THE MIDDLE OF THE WEEK.
THE WEDGE LOOKS TO FINALLY BREAK DOWN SOMETIME MONDAY WHICH WILL
ALSO ALLOW FOR A MORE DIURNALLY DRIVEN PRECIP PATTERN THROUGH DAY 7.
BEST TIMING FOR THE HEAVIEST RAIN WILL BE IN THE SHORT TERM BUT DEEP
TROPICAL MOISTURE REMAINS OVER THE REGION THROUGH WED/THU WITH
PRECIPITABLE WATERS IN THE 1.5 TO 2.0 INCH RANGE THROUGH THU. THE
DEEPER MOISTURE MOVES NORTH AND EAST OF THE STATE BY THU NIGHT BUT
THE DIURNAL CONVECTIVE TREND WILL CONTINUE INTO NEXT WEEKEND. TEMPS
WILL BEGIN TO REBOUND BY TUE AND BE BACK TO NEAR SEASONAL NORMS BY
THU/FRI.
01
&&
.AVIATION...
00Z UPDATE...
FRONTAL BOUNDARY JUST SOUTH OF ATL SHOULD REMAIN NEARLY STATIONARY
THROUGH THE NIGHT. LIGHT EAST WINDS WILL PERSIST OVERNIGHT AND
CONTINUE AROUND 10KT AFTER 14Z MONDAY. ALL SITES WILL GO IFR BY LATE
THIS EVENING AND THEN LIFR FOR THE EARLY MORNING HOURS. PREVAILING
SHOWERS CONTINUING WITH SOME SCATTERED THUNDERSTORMS. A FEW STORMS
POSSIBLY SEVERE.
//ATL CONFIDENCE...00Z UPDATE...
MEDIUM ON ALL ELEMENTS
41
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 69 81 69 79 / 50 60 50 70
ATLANTA 69 79 70 79 / 70 50 40 60
BLAIRSVILLE 65 76 66 78 / 70 50 50 60
CARTERSVILLE 69 79 69 78 / 70 50 50 60
COLUMBUS 71 83 72 85 / 50 60 40 70
GAINESVILLE 68 78 69 76 / 70 50 50 70
MACON 70 82 70 82 / 40 60 40 60
ROME 69 80 70 80 / 70 50 50 60
PEACHTREE CITY 70 80 71 79 / 60 50 40 60
VIDALIA 72 86 72 86 / 40 60 40 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING
ZONES: BARTOW...BIBB...BLECKLEY...BUTTS...CARROLL...CATOOSA...
CHATTAHOOCHEE...CHATTOOGA...CHEROKEE...CLAYTON...COBB...COWETA...
CRAWFORD...CRISP...DADE...DEKALB...DODGE...DOOLY...DOUGLAS...
FANNIN...FAYETTE...FLOYD...GILMER...GORDON...HARALSON...HARRIS...
HEARD...HENRY...HOUSTON...LAMAR...MACON...MARION...MERIWETHER...
MONROE...MURRAY...MUSCOGEE...NORTH FULTON...PAULDING...PEACH...
PICKENS...PIKE...POLK...PULASKI...ROCKDALE...SCHLEY...SOUTH
FULTON...SPALDING...STEWART...SUMTER...TALBOT...TAYLOR...
TELFAIR...TROUP...TWIGGS...UPSON...WALKER...WEBSTER...
WHITFIELD...WILCOX.
&&
$$
SHORT TERM...DEESE
LONG TERM....BDL
AVIATION...41
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
346 PM EDT SAT AUG 17 2013
...WET PATTERN TO CONTINUE FOR THE REMAINDER OF THE WEEKEND...
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
LOW LEVEL FLOW OVER 300K ISENTROPIC SURFACE HAS BECOME MORE
SOUTHERLY AND CROSS FLOW ALLOWING FOR ENHANCED LIFT NORTH OF
FRONTAL BOUNDARY OVER SOUTH GEORGIA. ENTRENCHED WEDGE ALSO
PROVIDING FOR ADDITIONAL FOCUS FOR THE DEVELOPMENT OF WIDESPREAD
LIGHT TO MODERATE RAIN OVER THE AREA. IN SITU CONDITIONS WITHIN
WEDGE ONLY HELPING TO STRENGTHEN ITS GRIP ON THE LOCAL AREA WITH
TEMPS REMAINING IN THE 60S FOR ALL OF NORTH GEORGIA. HAVE PRETTY
MUCH KEPT STEADY TEMPS IN THE FORECAST FOR THE SHORT TERM PERIOD
WHICH IS SOME 3 TO 6 DEGREES BELOW MODEL GUIDANCE WHICH IS NOT
PERFORMING WELL WITH THIS SUMMER WEDGE SCENARIO.
FOR TONIGHT...AXIS OF PRECIP SHOULD REMAIN IN ROUGHLY THE SAME
LOCATION AS MAIN FEATURES ARE STEADY STATE THROUGH THE OVERNIGHT
HOURS. EXPECT AT LEAST SOME DIURNAL INFLUENCES TO PRECIP COVERAGE
AND WILL GRADUALLY DECREASE...BUT KEEP A LARGE AREA OF LIKELY
THROUGH SUNDAY MORNING. GFS AS WELL AS SHORT TERM HRRR AND WRF IN
AGREEMENT IN DEPICTING A STRONG SHORTWAVE PUSHING OUT OF THE GULF
TOWARD DAYBREAK SUNDAY IN CONJUNCTION WITH A POSSIBLE BREAKDOWN OF
WEDGE FOR THE EXTREME SOUTHERN SECTIONS. SHOULD SEE REDEVELOPMENT
OF SHOWERS ON THE WEST SIDE OF THE FORECAST AREA WITH CONVECTIVE
ELEMENTS INCREASING AS WELL WHICH WILL LEAD TO HIGHER RAINFALL
RATES FROM COLUMBUS TO MACON. UPPER LEVEL FEATURE WILL LIFT NORTH
THROUGH LA GRANGE AND ATLANTA INTO THE AFTERNOON WITH CATEGORICAL
POPS EXPECTED ONCE AGAIN. BEST CAPE REMAINS TO THE SOUTH BUT THE
ADDITION OF SHORTWAVE ENERGY COULD HELP OVERCOME A LACK OF
INSTABILITY FOR THE NORTH AND WILL NEED TO BE MONITORED CLOSELY.
AT THE VERY LEAST...POTENTIAL FOR HEAVIER SUSTAINED SHOWERS WILL
INCREASE SUNDAY. WILL LET MID SHIFT TAKE ANOTHER LOOK BUT MAY NEED
TO EXTEND FLOOD WATCH THROUGH THE REMAINDER OF SUNDAY.
PRETTY MUCH THE SAME INTO SUNDAY NIGHT WITH FOCUS SHIFTING TO
NORTHWEST GA WITH SHORTWAVE. HAVE BACKED OFF OF CATEGORICAL AS
DIURNAL INFLUENCES SHOULD STILL BE IN PLAY BUT STILL PAINTING
LIKELY FOR THE FIRST PART OF THE OVERNIGHT PERIOD.
DEESE
.LONG TERM /MONDAY THROUGH SATURDAY/...
CHANGES TO THE LONG TERM ARE MINOR. HAVE TWEAKED POPS BASED OFF
THE LATEST MODELS. OTHER THAN THAT...ADJUSTED TEMPERATURES DOWN
A DEGREE OR SO FROM GUIDANCE FOR MONDAY. PREVIOUS DISCUSSION
FOLLOWS.
11
/ISSUED AT 452 AM EDT SAT AUG 17 2013/
THE GFS AND ECMWF MODELS REMAIN CONSISTENT IN CONTINUING THIS WET
PATTERN THROUGH THE WEEKEND AND INTO NEXT WEEK. THE STATIONARY
FRONT OVER SOUTH GA WILL MOVE SLOWLY NORTHWARD THROUGH MONDAY/TUE
THEN GRADUALLY DISSIPATE. AN EASTERLY LOW LEVEL FLOW WITH
ATLANTIC MOISTURE AND OVERRUNNING TROPICAL MOISTURE FROM THE GULF
WILL COMBINE WITH A SERIES OF UPPER LEVEL DISTURBANCES TO PRODUCE
WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS THROUGH WED/THU. BEST
TIMING FOR HEAVY RAIN WILL BE IN THE SHORT TERM BUT DEEP TROPICAL
MOISTURE REMAIN OVER THE REGION THROUGH DAY 6/7. PRECIPITABLE
WATERS REMAIN IN THE 1.5 TO 2.0 INCH RANGE THROUGH THU. THE
MODELS ARE TRYING TO ERODE THE WEDGE A BIT TO FAST ALLOWING
INSTABILITIES TO INCREASE ACROSS THE AREA MONDAY. THERE APPEARS TO
BE NO EROSION MECHANISM AND REINFORCEMENT OF THE COLD AIR DAMMING
IS LIKELY TO CONTINUE WITH SOLAR SHELTERING FROM OVERRUNNING
MOISTURE AND ANY EVAPORATIONAL COOLING. THIS WEDGE SHOULD CONTINUE
AT LEAST INTO EARLY NEXT WEEK ALLOWING INSTABILITY INDICES TO STAY
LOW FOR THIS TIME OF YEAR. WILL DEFINITELY NEED TO WATCH THIS AS IT
WILL PLAY A BIG ROLE IN OUR WEATHER PATTERN. TEMPS SHOULD BEGIN TO
REBOUND BY TUE BUT STILL STAY A BIT BELOW SEASONAL NORMS.
01
&&
.HYDROLOGY...
WITH CHANGING MODEL DEPICTIONS OF PRECIP PATTERN COMES CHANGES IN
ANTICIPATED HEAVIEST PRECIP CORE. EXPECTING CONVECTIVE ELEMENTS TO
EMANATE OUT OF THE GULF TONIGHT AND TRANSITION ON THE WESTERN SIDE
OF THE FORECAST AREA SUNDAY. THIS WILL PUT US SLIGHTLY OUT OF
PHASE WITH CURRENT FLOOD WATCH BUT FEELING IS THAT EVEN AREAS OVER
THE SOUTH THAT RECEIVE LESS RAINFALL COULD STILL REALIZE FLOODING
GIVEN EXTREMELY LOW FLASH FLOOD GUIDANCE VALUES. HAVE FLOOD WATCH
GOING THROUGH 12Z SUNDAY NIGHT WITH POSSIBLE EXPANSION BY MID
SHIFT IN BOTH TIME AND AREA.
&&
.CLIMATE...
RECORDS FOR 08-17
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAHN 105 1954 73 1939 76 2010 60 1967
2007 1948
1995
KATL 101 2007 74 1939 76 2010 62 1948
1954 1892 2000 1892
1995
KCSG 102 2000 82 1979 78 2001 66 1961
KMCN 103 2000 76 1939 77 2010 60 1967
1954 1952
RECORDS FOR 08-18
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAHN 103 1995 70 1905 76 1946 62 1979
1976
1964
KATL 101 2000 70 1981 80 2000 62 1964
1995 1905 1879
KCSG 104 2000 78 1981 78 2000 62 1948
1995
KMCN 104 2000 75 1981 77 2000 63 1948
1905 1995
1951
RECORDS FOR 08-19
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAHN 105 1925 75 1981 75 1934 61 1976
KATL 99 1925 69 1897 76 2010 63 1879
2007
1993
KCSG 100 2000 78 1992 78 2010 64 1958
1977
KMCN 101 1983 77 1977 77 1999 64 2006
1925 1976
RECORDS FOR 08-20
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAHN 107 1925 75 1976 77 1983 59 1943
1953
KATL 100 1925 77 1953 80 1925 59 1927
1927
KCSG 102 1983 78 1981 77 2010 66 1961
1948
KMCN 105 1925 74 1897 76 2010 62 1943
1983
1936
&&
.AVIATION...
18Z UPDATE...
PRECIPITATION SHIELD WHICH NOW ENCOMPASSES ALL THE AREA TAF SITES
HAS RESULTED IN LOWER CIGS AND VSBYS MAINTAINING THEMSELVES THIS
AFTERNOON. MOST SITES ARE IN THE IFR RANGE WITH BRIEF DIPS INTO
LIFR AS HEAVIER SHRA PASS THROUGH. LOOKS LIKE A PERSISTENCE
FORECAST THIS CYCLE WITH IFR TO CONTINUE INTO THE EVENING
HOURS...TRANSITIONING TO A LONG PERIOD OF LIFR INTO THE OVERNIGHT
PERIOD. SHRA SHOULD EASE BY LATE THIS EVENING BUT ADDITIONAL SHRA
EXPECT BY MID MORNING SUNDAY.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM ON CIGS.
HIGH ON REMAINING ELEMENTS.
DEESE
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 64 71 68 82 / 100 70 50 40
ATLANTA 64 72 69 81 / 80 100 70 50
BLAIRSVILLE 61 69 64 78 / 80 100 70 40
CARTERSVILLE 64 71 68 82 / 70 100 70 40
COLUMBUS 69 81 72 85 / 80 80 60 50
GAINESVILLE 63 71 68 79 / 80 100 70 40
MACON 68 79 71 85 / 100 60 50 50
ROME 66 71 69 84 / 60 100 70 40
PEACHTREE CITY 66 73 69 82 / 80 100 70 50
VIDALIA 69 82 72 87 / 100 40 30 50
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH SUNDAY MORNING FOR THE FOLLOWING
ZONES: BALDWIN...BIBB...BLECKLEY...BUTTS...CHATTAHOOCHEE...
CRAWFORD...CRISP...DODGE...DOOLY...EMANUEL...GLASCOCK...GREENE...
HANCOCK...HARRIS...HOUSTON...JASPER...JEFFERSON...JOHNSON...
JONES...LAMAR...LAURENS...MACON...MARION...MERIWETHER...MONROE...
MONTGOMERY...MORGAN...MUSCOGEE...PEACH...PIKE...PULASKI...
PUTNAM...SCHLEY...STEWART...SUMTER...TALBOT...TALIAFERRO...
TAYLOR...TELFAIR...TOOMBS...TREUTLEN...TROUP...TWIGGS...UPSON...
WARREN...WASHINGTON...WEBSTER...WHEELER...WILCOX...WILKES...
WILKINSON.
&&
$$
SHORT TERM...DEESE
LONG TERM....11
AVIATION...DEESE
AREA FORECAST DISCUSSION
NWS JACKSON KY
942 PM EDT SUN AUG 18 2013
.UPDATE...
ISSUED AT 942 PM EDT SUN AUG 18 2013
THE WIDELY SCATTERED SHOWERS AFFECTING THE AREA DURING THE EVENING
HAVE DECREASED IN COVERAGE AT THIS TIME ON THIS SIDE OF THE KY/VA
BORDER. TO THE EAST OF THE BORDER...A BAND OF SHOWERS CONTINUES TO
ADVANCE NORTHEASTWARD. THESE SHOWERS WILL SKIRT OUR VA BORDER
COUNTIES THROUGH THE NIGHT INTO TOMORROW MORNING AND WILL MAINTAIN
HIGHEST POPS IN THAT AREA...WITH DIMINISHING RAIN CHANCES TO THE
WEST. LATEST HRRR RUN SHOWS SOME SHOWERS DEVELOPING BACK FURTHER TO
THE WEST TOWARDS DAWN AND WITH THE FILLING UPPER LOW NEARBY...WILL
MAINTAIN AT LEAST A 20 POP EVERYWHERE THROUGH THE NIGHT INTO THE DAY
TOMORROW.
OTHERWISE...ADDED PATCHY FOG INTO THE FORECAST AS ANY BREAKS IN THE
CLOUDS WILL ALLOW IT TO FORM RATHER QUICKLY OVERNIGHT BUT NO OTHER
CHANGES WERE NEEDED AT THIS TIME.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 220 PM EDT SUN AUG 18 2013
UPPER LOW SPINNING OVER WRN KY WILL CONTINUE TO EASE TO THE EAST AS
HIGH PRESSURE SLOWLY RELEASES IT/S HOLD ON THE REGION AND SLIPS TO
THE MID ATLANTIC COAST. MEANWHILE A SFC LOW COMING ONSHORE NEAR THE
MID GULF COAST CONTINUES TO PUSH MOISTURE AND A BLANKET OF CLOUDS
INTO ERN KY. EXPECT THE RAIN TO CONTINUE OVER ERN KY FOR THE NEXT
24-30 HRS AS THE UPPER LOW EDGES ACROSS THE STATE AND FINALLY MOVES
NE TOWARDS THE NEW ENG COAST. THE GULF COAST LOW WILL SLOWLY TRACK NE
AND LINK UP WITH THE UPPER LEVEL SYSTEM BEFORE SWEEPING INTO THE
POCONOS. HIGH PRESSURE WILL THEN BUILD BACK INTO THE AREA AND GIVE
THE REGION A SMALL WINDOW TO DRY OUT ON MON NIGHT. BUT THE MOISTURE
SPLAYED ACROSS THE AREA TODAY AND TONIGHT WILL SET THE STAGE FOR FOG
MON NIGHT AS A FEW BREAKS IN THE CLOUD COVER WILL ALLOW TEMPS TO
DROP FROM A MON HIGH AROUND 80 TO LOWS AT OR NEAR THE DEWPOINT TEMPS
IN THE LOWER 60S FOR MON NIGHT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 231 PM EDT SUN AUG 18 2013
MODELS HAVE CHANGED COURSE A BIT GOING INTO TUESDAY AND WEDNESDAY AS
ANOTHER MID/UPPER LEVEL LOW WILL DEVELOP OVERHEAD. ON
TUESDAY...MOISTURE WILL BE ON THE INCREASE FROM THE SOUTH. MUCH LIKE
ON SATURDAY...DOWNSLOPING SOUTHEAST WINDS WILL HAMPER THE NORTHWARD
PROGRESS OF ANY PRECIPITATION AND KEEP INSTABILITY AT BAY.
THUS...GOING TO CONFINE POPS TO MAINLY THE SOUTHERN 2 ROWS OF
COUNTIES IN KENTUCKY WITH ONLY A SLIGHT CHANCE. AREAS FURTHER NORTH
WILL LIKELY BE AFFECTED BY THE DOWNSLOPING CONDITIONS. BY TUESDAY
NIGHT...AS THE UPPER LEVEL LOW PUSHES SLIGHTLY EAST...WINDS WILL
VEER AROUND TO THE SOUTH OR SOUTHWEST ALLOWING MOISTURE TO SURGE
NORTHWARD. CLOUDS AND SHOWERS WILL OVERSPREAD THE AREA FROM LATE
TUESDAY NIGHT INTO WEDNESDAY. A MID LEVEL VORTICITY MAXIMUM WILL
PUSH EAST DURING THE DAY TO AID IN MORE VIGOROUS SHOWER ACTIVITY.
STILL SOME QUESTION AS TO INSTABILITY DURING THE DAY...AND MUCH LIKE
TODAY...CLOUD COVER COULD LIMIT INSTABILITY KEEPING ANY THUNDER AT
BAY. GOING TO CARRY A SLIGHT CHANCE FOR NOW...BUT FEEL THIS THUNDER
PROBABLY WILL NOT PAN OUT. THIS SYSTEM WILL FINALLY BE ON THE WAY
OUT BY THURSDAY WITH THE EXPECTED RIDGING FINALLY BUILDING ACROSS
THE REGION. THIS WILL SET UP THE SUMMER-LIKE PATTERN BY THURSDAY AND
THROUGH NEXT WEEKEND. THIS WILL YIELD A MINIMAL CHANCE FOR SHOWERS
OR STORMS EACH AFTERNOON...BUT ANTICIPATING THAT MOST AREAS WILL
REMAIN DRY FROM WEDNESDAY NIGHT ONWARD. TEMPERATURES WILL REMAIN A
TOUCH BELOW NORMAL INTO WEDNESDAY WITH THE CLOUD COVER AND
PRECIPITATION...BUT WILL WARM TO NEAR NORMAL FOR THE SECOND HALF OF
THE WEEK...AND AT THIS POINT...LOOKING FOR SLIGHTLY ABOVE NORMAL
READINGS BY NEXT WEEKEND.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 721 PM EDT SUN AUG 18 2013
BELOW AVERAGE CONFIDENCE IN FORECAST DETAILS FOR AREA AIRPORTS
TONIGHT AS CLOUDS ARE EXPECTED TO BREAK UP ENOUGH TO ALLOW FURTHER
LOW CLOUD AND FOG DEVELOPMENT LATER TONIGHT WITH AMPLE LOW LEVEL
MOISTURE IN PLACE. WILL FORECAST DETERIORATING CONDITIONS AT ALL 3
TAF SITES WITH A PERIOD OF LIFR CIGS/VSBYS AROUND DAWN. SHOULD MID
LEVEL CLOUDS HOLD IN THROUGH THE NIGHT...THIS WILL BE TOO
PESSIMISTIC. OTHERWISE...A FEW STRAY SHOWERS WILL BE POSSIBLE THIS
EVENING AND THEN AGAIN TOMORROW AND WILL HANDLE WITH A VCSH MENTION
AT THIS TIME.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...ABE
SHORT TERM...DUSTY
LONG TERM...KAS
AVIATION...ABE
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
207 AM EDT SAT AUG 17 2013
.SYNOPSIS...
LOW PRESSURE WILL SLOWLY MOVE NORTHEAST ALONG THE MID ATLANTIC
COAST THIS WEEKEND. HIGH PRESSURE RETURNS EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
WILL BE MAKING SIGNIFICANT CHANGES TO THE GRIDS THROUGH 00Z SUN
WITH THE 1 AM UPDATE. MAIN CHANGE WILL TO LWR RAIN CHANCES ACROSS
THE NRN HALF OF FA AND LIMITING IT TO SAT AFTRN. IT MAY NOT RAIN
AT ALL ACROSS THE LW MD ERN SHORE UNTIL SAT EVE. RAIN CHANCES
SLOWLY INCRS THROUGH THE DAY ACROSS THE SOUTH. THIS ALL BASED ON
LATEST DATA WHERE THE MODELS ARE SHOWING DRYER AIR FROM THE HIGH
PRS OVR THE AREA WINNING OUT ACROSS THE FA THRU AT LEAST 18Z.
PVS DSCN:
UPDATE AS OF 1045 PM EDT...ANOTHER STRANGE EVENING WHERE WX
HAS BEEN TRENDING DRIER THAN EXPECTED. A BAND OF CLOUDS IS
CURRENTLY MOVING OFF THE COAST AND A BATCH OF RAIN HAS DEVELOPED
OVER THE VA TIDEWATER AND NE NC. WILL CONTINUE TO CARRY LIKELY
POPS IN THIS AREA THRU EARLY AM AS PCPN EXITS.
ELSEWHERE...CLEARING HAS WORKED INTO CENTRAL VA AND WILL CONTINUE
TO ADVANCE EAST THRU EARLY AM. THIS CLEARING HAS ALLOWED TEMPS TO
FALL A LITTLE LOWER THAN EXPECTED AND THUS HAVE LOWERED OVN LOWS A
FEW DEGREES. LOWS IN THE UPR 50S NW TO THE MID 60S SE. THERE IS
SOME INDICATION IN THE LATEST IR SATELLITE IMAGERY AND SFC OBS
THAT CLOUDS MOVING NORTHWARD THRU CENTRAL NC WILL SPREAD OVER OUR
AREA DURING THE PRE-DAWN HOURS SO WILL HAVE CLOUDS RETURNING
OVERNIGHT. HOWEVER..QUESTIONS REMAIN AS TO JUST HOW MUCH PCPN WILL
PUSH NORTHWARD BY DAYBREAK. LATEST NAM AND HRRR ARE NOT THAT
EXCITED ABOUT RAIN GETTING NORTH OF THE HWY 58 IN SOUTHERN VA TIL
AFTER 15Z SAT...SO NEXT SHIFT WILL LIKELY BE TRIMMING POPS BACK
EVEN FARTHER FOR SAT MORN.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
UPPER LEVEL HIGH PRESSURE OVER THE CTRL ATLANTIC SHIFTS TWD THE SE
COAST OVER THE WEEKEND. MEANWHILE...AN UPPER TROUGH WILL STAY WELL
ROOTED IN THE OH/TN VALLEYS DUE TO AN AMPLIFYING RIDGE OVER THE
GREAT BASIN. THE COMBINATION OF THESE UPPER LEVEL FEATURES WITH
THE STALLED SFC BOUNDARY ALONG THE CAROLINA COAST WILL CAUSE
MOISTURE AND SHORTWAVE ENERGY TO STREAM ACROSS THE MID ATLANTIC
REGION SATURDAY THROUGH SUNDAY NIGHT. A CONTINUATION OF FAVORABLE
ISENTROPIC LIFT MOVING INTO THE AREA FROM THE SOUTHWEST ON
SATURDAY WILL QUICKLY SATURATE THE LOWER ATMOSPHERE AND ACT TO
ENHANCE STEADY PRECIPITATION/RAINFALL. PWATS WILL GRADUALLY
INCREASE THROUGH THE WEEKEND FROM ROUGHLY 0.75 INCHES NORTH TO
1.50 INCHES SOUTH FOR TONIGHT...TO AROUND 2.00 INCHES NORTH TO
2.35 INCHES SOUTH BY SUNDAY. THE BEST POTENTIAL FOR WIDESPREAD
STEADY RAIN IS SATURDAY NIGHT. HOWEVER THE WEEKEND WILL NOT BE A
COMPLETE WASHOUT...BUT DO EXPECT PERIODS OF RAIN THAT WILL BE
MODERATE TO HEAVY AT TIMES AND MOSTLY CLOUDY TO CLOUDY SKIES. FOR
SUNDAY...FORECAST MODELS ARE HINTING AT A DRY SLOT MOVING INTO
NE NC AND SE VA DURING THE DAY AS THE ATLANTIC HIGH PUSHES CLOSER
TO THE SOUTHEAST COAST. IF THIS OCCURS...THEN THERE COULD BE A
NICE REPRIEVE FROM THE RATHER WET WEEKEND RAINS IN THE
AFOREMENTIONED AREAS. AT THIS TIME...IT IS DIFFICULT TO PINPOINT
EXACTLY WHERE THE DRIER CONDITIONS MAY SET UP AND HAVE THEREFORE
KEPT A CHANCE OF PRECIP IN THE ONGOING FORECAST FOR SUNDAY
AFTN/EVENING. DUE TO EXTENSIVE CLOUD COVER AND COOLER AMBIENT AIR
DUE TO EVAPORATIVE COOLING PROCESSES...TEMPERATURES WILL BE ON THE
COOL SIDE WITH HIGHS SAT/SUN GENERALLY IN THE 70S (NEAR 80 NE
NC/FAR SE VA ON SUN DUE TO POTENTIAL DRY SLOT/CLEARING). THE LOWS
ON SATURDAY NIGHT WILL GENERALLY BE IN THE 60S (NEAR 70 COASTAL
NE NC/FAR SE VA).
THE OH/TN VALLEY TROUGH AND GREAT BASIN HIGH BOTH BEGIN TO WASH
OUT ON MONDAY AND APPEAR TO RESULT IN A PSEUDO-WESTERLY (OR ZONAL)
FLOW. AT THIS TIME...IT SHOULD BE ENOUGH TO START PUSHING THE
PERSISTENTLY RAINY WX PATTERN OUT OF THE AREA BUT NOT UNTIL
TUESDAY/TUESDAY NIGHT. HIGH TEMPERATURES REBOUND INTO THE LOWER
80S SINCE A COMBINATION OF SUN AND CLOUDS ARE ANTICIPATED DURING
THE DAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
STRONG UPPER-LEVEL WESTERLY FLOW PREVAILS OVER SOUTHERN CANADA
THROUGH THE MIDDLE AND LATER PORTIONS OF NEXT WEEK. UNDERNEATH
THIS ZONAL FLOW...MID-LEVEL ANTICYCLONES WILL REMAIN NEARLY
STATIONARY OVER THE SOUTHERN PLAINS AND WESTERN ATLANTIC. AN AREA
OF (SOMEWHAT) LOWER HEIGHTS IS PROGGED OVER THE APPALACHIAN
PLATEAU. HOWEVER...THE MID ATLANTIC REGION SHOULD LARGELY REMAIN
UNDER THE INFLUENCE OF THE WESTERN ATLANTIC RIDGE. HENCE...
PRECIPITATION POTENTIAL SHOULD BE MINIMAL (NEAR OR BELOW CLIMO)
DUE TO A LACK OF LARGE SCALE FORCING FOR STORM ORGANIZATION...
DESPITE A WARM AND INCREASINGLY HUMID AIRMASS. HIGH TEMPERATURES
SHOULD AVERAGE AROUND SEASONAL NORMALS TUESDAY THROUGH FRIDAY
(MID/UPPER 80S)...WITH A FEW 90 DEGREE HIGHS POSSIBLE IN FAVORED
HOT SPOTS. LOWS SHOULD PRIMARILY RANGE FROM THE UPPER 60S TO LOW 70S.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
A NEARLY STATIONARY COASTAL FRONT HAS ORIENTED ALONG THE SE
COAST AS HIGH PRESSURE REMAINS OVER THE NE STATES. THE RESULT IS
CONTINUED NELY ONSHORE FLOW OVER THE LOCAL AREA. VISIBLE ON IR
SATELLITE AND SFC OBS...IS A WAVE OF LOW PRESSURE LIFTING ALONG
THE FRONT. INCREASING MOISTURE AND THE LIFTING WAVE WILL PROVIDE A
BETTER FOCUS FOR SHOWERS BEGINNING THIS MORNING OVER NC AND
SPREADING NWD DURING THE DAY. FOR THIS MORNING...MID/HIGH LEVEL
CLOUDS WILL CONTINUE TO STREAM IN FROM THE SOUTH. LOW CLOUDS WILL ALSO
LIFT FROM NC INTO SE VA/NE NC...RESULTING IN MVFR/LOCALLY IFR CIGS
THROUGH 12Z (KECG EXPECTED TO REMAIN IFR THROUGH 12Z).
THEREAFTER...EXPECT MIXING TO LIFT LOCALIZED IFR CIGS TO
MVFR...WITH MVFR CIGS (1500-2500 FT AGL) THROUGH MUCH OF THE DAY
WITH PRECIP. ELSEWHERE ...BKN-OVC SKIES WITH DECKS 4-7K FT AGL
EXPECTED IN ADVANCE OF THE LIFTING WAVE. AS PRECIP MOVES IN...CIGS
WILL LIKELY FALL TO MVFR (1500-2500 FT AGL) AND REMAIN THROUGH THE
TAF PERIOD. EXACT TIMING OF THE PRECIP REMAINS TRICKY ATTM...SO
WILL ADJUST TAFS BASED ON LATEST GUIDANCE/TRENDS. WINDS WILL
REMAIN OUT OF THE NE-E GENERALLY 10 TO 15 KT.
UNSETTLED CONDITIONS WILL CONTINUE THROUGH THE WEEKEND AS THE
COASTAL FRONT REMAINS NEARLY STATIONARY. HIGH PRESSURE WILL REMAIN
TO THE NORTH WITH NE-E FLOW OVER THE LOCAL AREA.
&&
.MARINE...
THE LATEST MSAS SURFACE ANALYSIS SHOWS A 1017MB LOW ~110NM ENE OF
CAPE HATTERAS TRACKING NE ALONG A COASTAL FRONT ALIGNED PARALLEL
TO THE SOUTHEAST COAST. A NE WIND (STRONGEST OFF THE CURRITUCK
OUTER BANKS) IS GRADUALLY DIMINISHING AS THE LOW PULLS AWAY AND
HIGH PRESSURE RETURNS FROM THE N. ANOTHER LOW (PRESENTLY OVER
SOUTHERN GA) IS PROGGED TO LIFT NE ALONG THE SOUTHEAST COAST
TONIGHT THROUGH SATURDAY...EVENTUALLY REACHING THE MID ATLANTIC
SATURDAY NIGHT AND SUNDAY...BEFORE PULLING TO THE NE SUNDAY NIGHT.
THIS PATTERN WILL MAINTAIN A PERSISTENT NE FLOW OVER THE REGION
THROUGH SATURDAY NIGHT FOR THE ENTIRE AREA...AND INTO SUNDAY FOR
THE NORTHERN PORTION OF THE MARINE AREA. WIND SPEEDS REMAIN CAPPED
AROUND 15KT ALONG WITH SEAS/WAVES CAPPED AT 4FT/3FT. CONFIDENCE ON
SCA HEADLINES REMAINS LOW...SO NO FLAGS WILL BE ISSUED. ALTHOUGH A
FEW BRIEF PERIODS OF SCA WIND ARE POSSIBLE ACROSS THE LOWER BAY
(4FT WAVES MOUTH OF THE BAY)...AND 5FT SEAS ARE POSSIBLE OUT NEAR
20NM IN THE OCEAN. HIGH PRESSURE RETURNS EARLY NEXT WEEK WITH
LIGHT SSW FLOW RETURNING...ALONG WITH 2-3FT SEAS.
PERSISTENT ONSHORE FLOW WILL RESULT IN AN ELEVATED RIP CURRENT RISK
SATURDAY AND POSSIBLY INTO SUNDAY AS WELL.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...MODERATE RIP CURRENT RISK FROM 8 AM EDT THIS MORNING THROUGH
THIS EVENING FOR MDZ025.
NC...MODERATE RIP CURRENT RISK FROM 8 AM EDT THIS MORNING THROUGH
THIS EVENING FOR NCZ102.
VA...MODERATE RIP CURRENT RISK FROM 8 AM EDT THIS MORNING THROUGH
THIS EVENING FOR VAZ098>100.
MARINE...NONE.
&&
$$
SYNOPSIS...BMD
NEAR TERM...JDM/MPR
SHORT TERM...BMD
LONG TERM...AJZ
AVIATION...SAM
MARINE...AJZ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
739 PM EDT SUN AUG 18 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 409 PM EDT SUN AUG 18 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE OVER THE SRN U.S.
ROCKIES WITH A TROF LINGERING OVER THE LWR MISSISSIPPI VALLEY. TO
THE N...ZONAL FLOW DOMINATES SRN CANADA. THERE ARE A COUPLE OF
SHORTWAVES OF INTEREST UPSTREAM IN THIS ZONAL FLOW. THE FIRST IS
OVER SE MANITOBA...AND THE SECOND IS OVER SRN SASKATCHEWAN/ERN MT.
THE FIRST WAVE IS GENERATING CONVECTION OVER FAR SE MANITOBA INTO
ADJACENT NRN ONTARIO. THE SECOND WAVE IS GENERATING SCT SHRA/TSRA
OVER THE WRN DAKOTAS INTO SRN SASKATCHEWAN. CLOSER TO HOME...12Z
SOUNDINGS FROM KGRB/KMPX SHOWED VERY DRY MID LEVELS AND A HEALTHY
CAP...AND THUS NO PCPN IS OCCURRING OVER THE FCST AREA THIS AFTN.
SOME CI AND A RATHER THICK ELEVATED SMOKE LAYER HAS HELD TEMPS DOWN
A BIT FROM EXPECTATIONS WITH READINGS MOSTLY IN THE UPPER 70S TO LOW
80S AS OF 19Z. NEAR LAKE MICHIGAN...SOUTHERLY WINDS OFF THE LAKE ARE
HOLDING TEMPS TO THE LOW/MID 70S.
AFTER A DRY START TO THE SHORT TERM...ATTENTION TURNS TO THE
POTENTIAL OF SHRA/TSRA LATE TONIGHT/MON AS THE PAIR OF SHORTWAVES
CURRENTLY OVER SE MANITOBA AND OVER SRN SASKATCHEWAN/ERN MT MOVES
EASTWARD. INITIAL DRY/CAPPED AIR MASS WILL ENSURE DRY WEATHER ACROSS
THE FCST AREA THIS EVENING. THEN...SW FLOW AHEAD OF SHORTWAVES WILL
TRANSPORT INTO THE UPPER LAKES THE MORE HUMID AIR MASS EVIDENT OVER
THE CNTRL PLAINS THIS MORNING PER 12Z RAOBS. WHILE THE ANTECEDENT
DRY AIR WILL WORK TO DELAY SHRA...DEGREE OF MOISTENING/MAGNITUDE OF
THETA-E ADVECTION SUGGESTS THERE WILL BE SOME RISK OF PCPN. THERE MAY
BE 2 RATHER DISTINCT CLUSTERS OF SCT SHRA/TSRA. THE FIRST ASSOCIATED
WITH THE SE MANITOBA SHORTWAVE COULD REACH NW LAKE SUPERIOR/ISLE
ROYALE AREA EARLY IN THE OVERNIGHT. 850-300MB THICKNESS FIELD
SUGGESTS SOME OF THE CURRENT SHRA/TSRA ASSOCIATED WITH THE WAVE MAY
TAKE A SHARP TURN TO THE RIGHT AS THEY APPROACH THE LAKE...SO IT
REMAINS TO BE SEEN WHERE THESE SHRA MAY END UP. THE SECOND AREA OF
CONVECTION MAY DEVELOP ACROSS NRN MN TOWARD WRN LAKE SUPERIOR LATE
IN THE NIGHT OR MON MORNING WITH THE FOLLOWING SHORTWAVE. IN BOTH
CASES...THERE IS AN INDICATION OF WEAKENING MOISTURE TRANSPORT
EASTWARD WITH TIME...SO SHRA WILL PROBABLY BE ON A DIMINISHING TREND
AS THEY MOVE TOWARD LAKE SUPERIOR/UPPER MI. AT THIS POINT...SEE NO
REASON TO DEVIATE MUCH FROM INHERITED FCST WHICH BROUGHT CHC POPS TO
WRN LAKE SUPERIOR OVERNIGHT AND SCHC POPS TO WRN UPPER MI LATE.
INCREASING COLUMN MOISTURE AND STIRRING S TO SW WINDS WILL WORK TO
KEEP TEMPS HIGHER THAN LAST NIGHT. EXPECT MINS IN THE MID 60S IN THE
DOWNSLOPE AREAS NEAR LAKE SUPERIOR. MINS IN THE MID 50S TO PERHAPS
AS LOW AS 50F IN TRADITIONAL COLD SPOTS SHOULD BE THE RULE INLAND.
ON MON...SHORTWAVE TROF MOVES ACROSS THE UPPER LAKES...BUT WILL BE
WEAKENING AS EVIDENT IN HEIGHT FIELD AND DEEP LAYER FORCING PER
QVECTORS. IF ANY SHRA/TSRA REACH THE W LATE TONIGHT...THEY WILL
LIKELY WEAKEN IN THE MORNING. DURING THE AFTN...MLCAPE IS FCST TO
INCREASE TO POSSSIBLY AS MUCH AS 800-1000J/KG. HOWEVER...WITH
DIMINISHING FORCING AND POTENTIALLY LITTLE IN THE WAY OF LAKE BREEZE
CONVERGENCE...COVERAGE OF ANY DIURNALLY DRIVEN CONVECTION WILL
PROBABLY BE QUITE LIMITED. WILL MAINTAIN JUST SCHC POPS FOR THE AFTN
HRS. MAX TEMPS SHOULD GENERALLY BE IN THE MID 80S PER FCST
SOUNDINGS. OF COURSE...SOUTHERLY WINDS WILL KEEP AREAS NEAR LAKE
MICHIGAN A LITTLE COOLER.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 409 PM EDT SUN AUG 18 2013
STARTING OUT ON MONDAY EVENING THE UPPER AIR PATTERN LOOKS ZONAL
WITH WEAK TROUGHING OVER THE GREAT LAKES AND A RIDGE CENTERED OVER
THE SOUTHWEST CONUS. RIDGE WILL HAVE HARD TIME AMPLIFYING FARTHER
NORTH INTO CANADA THIS WEEK THOUGH AS STRONGER WESTERLIES H5-H3
STREAM ACROSS SOUTHERN TIER OF CANADA OUT OF A MORE OR LESS
PERSISTENT TROUGH SET UP OVER GULF OF ALASKA. EVENTUALLY...WEDNESDAY
NIGHT INTO THURSDAY...LARGER SCALE HEIGHTS FALL SOME AS STRONGER
SHORTWAVE/JET MAX...PART OF WHICH IS STREAMING TOWARD WESTERN SHORE
OF BRITISH COLUMBIA TODAY...DIGS ACROSS NORTHERN ONTARIO TO WESTERN
QUEBEC. SFC COLD FRONT CROSSES UPPER LAKES WEDNESDAY AFTN INTO
WEDNESDAY NIGHT JUST AHEAD OF BETTER HEIGHT FALLS BEGIN LATE
WEDNESDAY. FRONT REPRESENTS BEST CHANCE OF SHRA/TSRA THIS WEEK. HIGH
PRESSURE BUILDS IN BEHIND THE FRONT...BUT QUESTION OF THE DAY IS FOR
HOW LONG. THIS WILL HAVE IMPACT ON FORECAST FOR FRIDAY THROUGH NEXT
WEEKEND.
INITIAL SHORTWAVE THAT ROLLS ACROSS UPPER LAKES ON MONDAY WILL
MAINLY BE EAST OF CWA MONDAY EVENING. SOUNDINGS SHOW PERHAPS MID
CLOUDS THROUGH THE NIGHT BUT WITH SUBSIDENCE IN WAKE OF WAVE...NOT
EXPECTING ANY SHRA/TSRA. ANOTHER WARM NIGHT IN THE 60S WITH STEADY
SW SFC WINDS BENEATH STRONGER WINDS AT 950-925MB. STRONGER WINDS
ALOFT FADE BY TUESDAY AFTN WHICH MAY RESULT IN LOCALIZED BACKING OF
WINDS/LAKE BREEZE ALONG LK SUPERIOR NCNTRL. LAKE MODIFICATION ONLY
ALONG LK MICHIGAN ELSEWHERE. MID CLOUDS MAY DAMPEN SUN INITIALLY...
BUT SHOULD SEE FULL SUN FOR A WHILE BTWN MID MORNING AND MID AFTN
ALLOWING TEMPS TO WARM WELL INTO THE 80S AND PROBABLY TO THE LOWER
90S IN SOME WESTERN CWA LOCATIONS. WILL HAVE TO REACH AT LEAST MID
80S BEFORE CU BEGINS TO FORM AND CONVECTIVE TEMPS ARE ON THE HIGH
SIDE IN THE LOWER 90S. SUPPOSE ALONG THE CONVERGENCE OF LAKE BREEZE
THERE COULD BE AN ISOLD STORM GIVEN MLCAPES OVER 2000J/KG. MOISTURE
THAT IS AROUND PER SOUNDINGS IS VERY SHALLOW SO WITHOUT MUCH
ADDITIONAL LARGE SCALE SUPPORT...THINK CHANCES ARE VERY MINIMAL. IF
A STORM CAN FORM...WOULD HAVE POTENTIAL FOR GUSTY WINDS AS DCAPE
VALUES ARE OVER 1000J/KG. SOUNDINGS POINT TO QUIET...WARM AND HUMID
CONDITIONS TUESDAY NIGHT IN THE WARM SECTOR. MAY SEE A TOUCH OF
FOG...THOUGH SOME WIND JUST OFF THE SFC WILL LIMIT THE EXTENT.
MOIST ONSHORE FLOW MAY LEAD TO MORE FOG CLOSER TO LK MICHIGAN SHORE.
WARM WEATHER CONTINUES ON WEDNESDAY. AFTER A WARM START NEAR 70
DEGREES IN SOME SPOTS IT WILL NOT TAKE MUCH TO SEE READINGS REACH
THOSE SIMILAR TO TUESDAY. COLD FRONT MAKES IT TO MN ARROWHEAD JUST
TO WEST OF DLH BY MIDDAY SO A LOT OF TIME FOR WARMING IN A CAPPED
AIRMASS WITH WARM NOSE AROUND 800MB. SOUNDINGS THROUGH 00Z THURSDAY
LOOK PRETTY DRY WHICH MAKES SENSE AS PRIMARY SHORTWAVE AND MOISTURE
ADVECTION IS NORTH OVR ONTARIO. SW WINDS COULD INCREASE THROUGH THE
DAY AS 950-925MB WINDS INCREASE. STILL THINK TEMPS ON WEDNESDAY MAY
END UP A BIT WARMER THAN TUESDAY WITH LATER ARRIVAL TO FRONT AND AS
H85 TEMPS ARE NEAR +20C TO START THE DAY. DOWNSLOPE MAY LEAD TO
FURTHER WARMING ALONG LK SUPERIOR FROM ONTONAGON TO MUNISING. WILL
BUMP TEMPS INTO UPR 80S ON AVERAGE AND PUSH DOWNSLOPE AREAS TO
AROUND 90. INSTABILITY OBVIOUSLY PRESENT AHEAD OF FRONT WITH THE
VERY WARM TEMPERATURES AND INCREASE IN BLYR MOISTURE /DWPNTS ARE WELL
INTO THE 60S/. RESULT IS MLCAPES 1500-2000J/KG JUST AHEAD OF THE
FRONT. THINK QUALITY OF MOISTURE ULTIMATELY WILL LIMIT CONVECTION
COVERAGE WITH THE FROPA. GIVEN THE INSTABILITY AND DEEP LAYER SHEAR
UP TO 30 KTS THERE IS AT LEAST A MARGINAL POTENTIAL FOR ISOLD SVR
STORMS THROUGH WEDNESDAY EVENING. HIGHER FREEZING LEVEL OVER 14KFT
AND DRY AIR ALOFT /DCAPE OVER 1000J/KG/ POINTS TO STRONG WIND GUSTS
AS MAIN HAZARD.
GOOD AGREEMENT THAT STRONG DRYING/SUBSIDENCE ENDS ANY SHRA/TSRA
OVERNIGHT WEDNESDAY NIGHT WITH THURSDAY STILL LOOKING MUCH COOLER
AND MAINLY DRY AS HIGH PRESSURE BUILDS ACROSS UPPER GREAT LAKES.
GUSTY NORTH TO NORTHWEST WINDS ALONG WITH COLD AIR ADVECTION SHOULD
KICK UP WINDS AND WAVES ON LK SUPERIOR LEADING TO ELEVATED SWIM
RISK. TEMPS WILL STRUGGLE TO 70 DEGREES NEAR LK SUPERIOR AND COULD
REACH LOWER 80S FAR SOUTH.
EVEN THOUGH THURSDAY IS AGREED UPON FOR COOLER AND MAINLY DRY
WEATHER THE FORECAST FOR THURSDAY NIGHT INTO FRIDAY NOT NEARLY AS
CLEAR CUT. GFS MAINTAINS CONTINUITY WITH RECENT RUNS BY SHOWING
SPRAWLING HIGH SHUNTING MAIN FRONTAL BOUNDARY AND FOCUS FOR RETURN
FLOW SHRA/TSRA OVER THE NORTHERN PLAINS AND OHIO VALLEY UNTIL AT
LEAST SATURDAY NIGHT. MEANWHILE...ECMWF UP TO 12Z RUN TODAY WAS
CONSISTENT SINCE 00Z RUN ON 17 AUG INDICATING ONLY A BRIEF HIGH
PRESSURE INTRUSION. ECMWF THEN SHOWS NEXT SHORTWAVE IN WESTERLY FLOW
FORMING A STRONGER SFC-H85 LOW OVER THE NORTHERN PLAINS THURSDAY
WITH ASSOCIATED WARM AIR ADVECTION SHRA/TSRA IMPACTING UPPER LAKES
AS EARLY AS THURSDAY NIGHT AND FRIDAY. ECMWF CERTAINLY ON THE
AMPLIFIED SIDE COMPARED TO ECMWF ENSEMBLE WHICH LOOKS MORE LIKE THE
OPERATIONAL GFS. LATEST ECMWF HAS BACKED AWAY FROM THIS IDEA THOUGH
JUST ADDING MORE UNCERTAINTY TO THIS TIME FRAME. DROPPED POPS FOR
THU NIGHT AND FRIDAY TO SLIGHT CHANCE...BUT WANTED TO KEEP SOME POPS
IN THERE IN CASE MODELS SHIFT BACK TO WETTER IDEA. MUDDLED FORECAST
CONTINUES THROUGH NEXT WEEKEND AS TIMING FOR SYSTEMS MOVING
THROUGH REST OF THE WEEKEND IS STILL OUT OF WHACK BTWN THE GFS AND
ECMWF. CONSENSUS APPROACH WORKS FOR NOW UNTIL THESE DETAILS CAN BE
BETTER SORTED OUT. AFTER THE COOLER TEMPS THURSDAY AND FRIDAY...SEEMS
THAT TEMPS WILL REACH BACK TOWARD NORMAL AND MAYBE EVEN ABOVE NORMAL
IF THERE IS NOT MUCH IN WAY OF CLOUDS OR PRECIPITATION.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 737 PM EDT SUN AUG 18 2013
WITH SW FLOW OF RELATIVELY DRY AIR...EXPECT VFR CONDITIONS TO
PREVAIL THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. INCREASING SW WINDS
ABOVE NOCTURNAL INVERSION TONIGHT WILL APPROACH LLWS CRITERIA.
ALSO A DISTURBANCE APPROACHING FROM THE W MAY BRING ISOLD/SCT
CONVECTION INTO UPPER MI LATE TONIGHT THRU MON MORNING. HOWEVER...AT
THIS POINT...CONFIDENCE IS VERY LOW ON ACTUAL OCCURRENCE OF
CONVECTION LET ALONG LOCATION/COVERAGE. THUS...NO MENTION OF
SHRA/TSRA WAS INCLUDED IN THIS FCST ISSUANCE. &&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 409 PM EDT SUN AUG 18 2013
OVERALL...EXPECT WINDS LESS THAN 20 KTS THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. SOME STRONGER SW WIND GUSTS UP TO 20-25KT MAY
OCCUR TONIGHT UNDER A SHARPER PRES GRADIENT AHEAD OF AN APPROACHING
DISTURBANCE. THE ARRIVAL OF MORE HUMID AIR FOR TUE/WED MAY RESULT IN
SOME FOG FORMATION OVER THE COOLER LAKE WATERS. HOWEVER...FOG WILL
BE MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS OCCUR OVER THE LAKE.
ANY FOG WILL DISSIPATE THU FOLLOWING A COLD FRONTAL PASSAGE AND THE
ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1040 PM MDT Fri Aug 16 2013
AVIATION SECTION UPDATED
.DISCUSSION...
Update forthcoming. Have made minor changes to the sky grids. Have
also expanded pop area over the extreme northwest portion of the
county warning area. HRRR analysis brings very light precipitation
to the area toward daybreak, likely associated with area of clouds
moving through the Idaho panhandle at this time. Temperatures look
reasonable. Emanuel
&&
.AVIATION...
UPDATED 0440Z.
Current satellite imagery shows weak upper level trough stretching
from southeast Alberta to the ID Panhandle moving faster and
bringing greater cloud coverage than forecast models had been
indicating. Not a big impact given that ceilings should remain above
10000 ft, but enough to adjust cloud timing and coverage in latest
KCTB/KGTF/KHVR TAFs. Have also added mention of VCTS vcnty KCTB
tomorrow aftn. Elsewhere, smoke from wildland fires in the western
portion of Montana and from eastern Idaho will keep thin layers of
high clouds over central and southwest MT overnight and much of
tomorrow. Surface winds remaining light through the overnight hours.
Waranauskas
&&
.PREV DISCUSSION...Issued 230 PM MDT Fri Aug 16 2013
Tonight through Sunday...Warm and dry conditions will continue
Friday afternoon into Saturday. High pressure slowly begins to
shift east in response to a weak mid level boundary passing
through the region early Saturday. There will be a slight chance
of some afternoon shower development over portions Central
Montana Saturday and Sunday but dry lower level conditions may
prevent most precipitation reaching the ground. Elevated terrain
will likely have a better chance of seeing any precipitation from
anything that does develop. Any storms that do develop will likely
only produce gusty winds near their vicinity. Fire weather
conditions are marginal at this time but very low relative
humidity and afternoon breeziness add to the danger level. For
additional fire weather concerns please see the Fire Weather
Discussion. Temperatures look to moderate slightly over the
weekend with highs dropping to the upper 80s and low 90s.
Sunday night through Friday...The zones will be underneath a flat
upper level high pressure ridge Sunday night and the airmass will
be quite dry. The next low pressure weather system will be well
west over the Eastern Pacific. The upper level ridge will move
east of the zones by Tuesday afternoon and flow aloft will switch
to the southwest. Moisture will again be able to move underneath
the ridge and the airmass will become unstable again Wednesday
afternoon, mainly over the southwest zones. Later in the week
latest model runs indicate that the upper ridge will rebuild and
affect the forecast area. Therefore have updated the forecast to
go with warmer temperatures. There is the possibility that high
temperatures could return to near 90 by late in the week for the
lower elevations. Even with this change to a rebuilding upper
ridge it still looks like there could be some instability so will
continue with the mention of a slight chance of thunderstorms even
though some guidance from the models indicates Thursday and Friday
could be dry. Blank
&&
.FIRE WEATHER...
UPDATED 2030Z. Critical fire weather conditions remain possible
into Friday evening before returning Saturday afternoon over
Southwest and South Central Montana. Afternoon humidity will drop
to very low values of 5 to 10 percent across the lower elevations
with slightly higher values of 10 to 15 percent Saturday. A weak
mid- level boundary passing through the region Saturday afternoon
could bring somewhat breezy westerly winds, mainly along and near
the Continental Divide. Not expecting a major wind shift or strong
winds from these boundaries though. Breezy winds combined with low
humidity could result in critical fire weather conditions Saturday
afternoon. Confidence remains high for humidity less than 20
percent and around 50 percent for winds over 15 mph Saturday. As a
result, will hold off on fire weather highlights at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 57 91 57 89 / 10 10 30 10
CTB 56 85 53 83 / 10 10 10 0
HLN 59 90 58 89 / 0 20 20 10
BZN 51 90 51 88 / 0 10 20 10
WEY 39 83 42 81 / 0 10 10 20
DLN 51 87 50 86 / 0 10 10 10
HVR 60 89 59 88 / 10 10 30 20
LWT 55 87 56 85 / 0 10 30 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING until 9 PM MDT this evening Beaverhead...
Central and Southern Lewis and Clark...Jefferson...Madison.
&&
$$
weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1230 PM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 555 AM CDT SAT AUG 17 2013
HELD OFF AS LONG AS WE COULD...BUT KUEX NOW INDICATES ISOLATED
SHOWER ACTIVITY DEVELOPING OVER ROOKS COUNTY. MEAGER ELEVATED
POTENTIAL INSTABILITY IS ALSO SUGGESTED BY RAP ANALYSIS PROXIMITY
SOUNDINGS AND THUS...OCCASIONAL LIGHTNING/THUNDER ALSO CANNOT BE
RULED OUT. WENT AHEAD WITH 20% POPS UNTIL 13Z FOR OUR EXTREME
SOUTHWESTERN CWA. THE LOW LEVEL JET SHOULD QUICKLY DIMINISH POST-
SUNRISE THUS ALLOWING FOR DIMINISHING SHOWER AND THUNDERSTORM
ACTIVITY. REMAINDER OF THE FORECAST WAS LEFT UNCHANGED.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 346 AM CDT SAT AUG 17 2013
OVERNIGHT MAP ANALYSIS INDICATES MID TO UPPER LEVEL LONGWAVE
RIDGING OVER THE WESTERN CONUS...WITH A TROUGH OVER THE EAST. MID
TO UPPER LEVEL JET ENERGY EXTENDS FROM THE WEST-CENTRAL
CONUS...NORTHEAST INTO SOUTHWEST AND SOUTH CENTRAL CANADA...AND
THEN SOUTHEAST ACROSS THE PLAINS...AND FINALLY EAST/NORTHEAST
ACROSS THE SOUTHEASTERN CONUS AND ON INTO THE EASTERN CONUS. MID
TO UPPER LEVEL FLOW OVER THE CENTRAL PLAINS REMAINS FROM THE
NORTH/NORTHWEST AS A RESULT...BUT IS NOT PARTICULARLY STRONG ONLY
MAXING OUT AT AROUND 45KTS NEAR 200MB PER 00Z SOUNDING DATA FROM
KLBF AND KOAX. WATER VAPOR IMAGERY ALSO SHOWS THE AFOREMENTIONED
LONGWAVE RIDGE AND TROUGH...WITH INCREASED VALUES OF MID LEVEL
MOISTURE FLOWING ALONG THE MID LEVEL JET AXIS. AT THE SURFACE A
LARGE AREA OF HIGH BAROMETRIC PRESSURE EXISTS OVER THE MISSOURI
AND MID MISSISSIPPI RIVER VALLEYS. LOW LEVEL FLOW ACROSS OUR AREA
REMAINS FROM THE SOUTHEAST AS A RESULT.
LOW LEVEL THERMAL ADVECTION ALONG THE AXIS OF A ~30KT 850MB JET
AXIS IS HELPING PROMOTE ISOLATED SHOWER AND THUNDERSTORM ACTIVITY
OVER PORTIONS OF WESTERN KANSAS THIS MORNING. ALTHOUGH THIS
ACTIVITY HAS REMAINED SOUTHWEST OF OUR CWA SO FAR
TONIGHT...GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...AND SREF-
MEAN ALL SUGGEST THE LOW LEVEL JET STREAK AXIS WILL VEER MORE INTO
OUR AREA TOWARDS 12Z. THE NAM AND EC BOTH SUGGEST LIGHT
PRECIPITATION WILL BE REALIZED OVER EXTREME SOUTHWESTERN PORTIONS
OF OUR CWA...A SOLUTION ALSO SUPPORTED TO AN EXTENT BY THE HRRR
AND 1KM WRF-NMM. ALL THAT BEING SAID...CONFIDENCE OF ANY ONE
LOCATION ACROSS OUR CWA...INCLUDING OUR SOUTHWESTERN
CWA...ACTUALLY OBSERVING MEASURABLE RAINFALL REMAINS VERY LOW AND
AS A RESULT...WILL CONTINUE WITH THE DRY FORECAST FOR EARLY THIS
MORNING AND CONTINUE TO MONITOR.
FOR THE REST OF TODAY AND TONIGHT...AN OVERALL LACK IN KINEMATIC
FORCING SHOULD PRESENT DRY CONDITIONS TO OUR AREA THROUGH TONIGHT.
MUCH LIKE THIS MORNING HOWEVER...THE ONLY EXCEPTION COULD BE
ACROSS OUR WEST/SOUTHWEST 06-12Z SUNDAY AS THE AXIS OF ~30KT 850MB
JET STREAK ONCE AGAIN DEVELOPS OVER PORTIONS OF THE CENTRAL HIGH
PLAINS. THAT BEING SAID...QPF FIELDS FROM VARIOUS MODELS DO NOT
SUGGEST MEASURABLE PRECIPITATION WILL BE REALIZED ANYWHERE ACROSS
OUR CWA AND GIVEN THIS...WILL GO AHEAD AND MAINTAIN A DRY FORECAST
THROUGH 12Z SUNDAY AND LET FUTURE SHIFTS REEVALUATE THE POTENTIAL
NEED FOR LOW POPS DURING THE EARLY MORNING HOURS ON SUNDAY.
CLOUD COVER REALLY KEPT TEMPERATURES ACROSS OUR CWA ON THE COOL
SIDE DURING THE DAY FRIDAY. THE STRATUS DECK HAS NOT BEEN NEARLY
AS DENSE AS EXPECTED TONIGHT HOWEVER AND THE CURRENT THINKING IS
THIS STRATUS SHOULD DISSIPATE AND LIFT BY MID TO LATE MORNING
WHICH SHOULD ALLOW FOR WARMER AFTERNOON HIGHS. GUIDANCE FROM THE
MET...MAV...AND ECS SEEMS TO HAVE A GOOD HANDLE ON THIS AND TAKING
AN EVEN AVERAGE OF THE THREE PROVIDES AFTERNOON HIGH TEMPERATURES
IN THE UPPER 70S TO NEAR 80 ACROSS MUCH OF THE CWA. CLEARER SKIES
SHOULD ALLOW FOR A SLIGHTLY COOLER OVERNIGHT LOWS TONIGHT WHEN
COMPARED TO EARLY THIS MORNING...WITH OVERNIGHT LOWS IN THE UPPER
50S TO NEAR 60 CURRENTLY FORECAST FOR MOST LOCATIONS TONIGHT.
FINALLY...NEAR-ZERO LOW LEVEL DEW POINT DEPRESSIONS AND A FAIRLY
LIGHT SOUTH/SOUTHEAST LOW LEVEL WIND FIELD COULD PROMOTE PATCHY
FOG ACROSS THE AREA TOWARDS SUNRISE SUNDAY. VISIBILITY RESTRICTION
IS NOT EXPECTED TO BE SIGNIFICANT...BUT WILL GO AHEAD WITH PATCHY
FOG IN THE GRIDS BEGINNING 09Z SUNDAY.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 346 AM CDT SAT AUG 17 2013
A RELATIVELY QUIET WEATHER PATTERN WILL BECOME EVIDENT BEGINNING
SUNDAY AS HIGH PRESSURE CONTINUES TO SLIDE OVER THE REGION FROM
THE INTERMOUNTAIN WEST.
WATER VAPOR IMAGERY DEPICTS A 500MB TROUGH OVER THE EASTERN PART
OF THE CONUS...WHILE HIGH PRESSURE IS BUILDING IN OVER MOST OF THE
WESTERN CONUS. THERE IS A SHORT WAVE TROUGH EVIDENT OVER THE
PACIFIC NORTHWEST AS WELL. MODELS ARE IN GOOD AGREEMENT WITH
REGARDS TO HIGH PRESSURE BUILDING IN FROM THE WEST TO CONTINUE.
THIS PATTERN WILL MAKE FOR WARMER DAYS AHEAD WITH TEMPERATURES
FORECAST TO BE MORE SEASONABLE THAN THE PREVIOUS WEEK. THE PATTERN
OVER THE NEXT WEEK IS SHOWING UNFAVORABLE CONDITIONS FOR ANY
PRECIPITATION AND HENCE A DRY FORECAST THROUGH MOST OF THE
EXTENDED AS HIGH PRESSURE DOMINATES THE REGION. THURSDAY NIGHT
INTO FRIDAY APPEARS TO BE THE ONLY DAY SHOWING ANY CHANCE FOR
PRECIPITATION...BUT THE LATEST RUNS OF THE GFS AND EC ARE BOTH
BEGINNING TO SHOW DRY CONDITIONS IN THE EXTENDED. SINCE THIS IS
THE FIRST RUN OF THE EC AND GFS AGREEING IN FAVOR OF DRIER
CONDITIONS...I WILL LEAVE THE SLIGHT CHANCES IN THERE FOR THURSDAY
NIGHT INTO FRIDAY UNTIL SOME CONSISTENCY EVOLVES. DONT WANT A FLIP
FLOP SCENARIO DEVELOPING. I CAN SEE THESE POPS GETTING YANKED IF
THIS TREND CONTINUES INTO DAY SHIFT THOUGH. SEEMS VERY REASONABLE
TO HAVE THE DRY FORECAST BASED ON THE HIGH PRESSURE STILL PROGGED
TO BE NEARLY CENTERED OVER THE CENTRAL PLAINS REGION COME FRIDAY.
WITH THE HELP OF HIGH PRESSURE BUILDING IN OVER THE
REGION...TEMPERATURES WILL BE MORE SEASONABLE THROUGH THE
EXTENDED. SUNDAY WILL BE THE COOLEST DAY OVER THE FORECAST
PERIOD...WITH HIGHS RANGING FROM THE LOWER 80S TO UPPER 80S.
MONDAY WILL BE SLIGHTLY WARMER. BUT BY TUESDAY...HIGH TEMPERATURES
NEAR 90 DEGREES WILL BE THE NORM THROUGH AT LEAST FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1221 PM CDT SAT AUG 17 2013
WILL CONTINUE TO SEE THE POTENTIAL FOR SOME LOWER LEVEL/MVFR CLOUD
COVER TO AFFECT THE TERMINAL AREA THROUGH THE AFTERNOON
HOURS...BUT IT DOESNT LOOK TO BE A SOLID DECK SO WILL KEEP AS A
TEMPO MENTION...AND CEILINGS SHOULD LIFT AS WE GET TOWARD LATER
THIS AFTERNOON. MODELS SHOWING THE REDEVELOPMENT OF STRATUS
TONIGHT BEING WEST OF THE TERMINAL...SO HAVE THE OVERNIGHT HOURS
INTO TOMORROW VFR AT THIS POINT. WINDS THROUGH THE TAF PERIOD WILL
REMAIN SOUTHERLY...AS THE AREA SITS BETWEEN HIGH PRESSURE FROM ERN
NEB UP INTO THE NERN CONUS...AND LOW PRESSURE OVER THE
ROCKIES/HIGH PLAINS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...BRYANT
SHORT TERM...BRYANT
LONG TERM...GUERRERO
AVIATION...ADO
AREA FORECAST DISCUSSION
NWS HASTINGS NE
555 AM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 555 AM CDT SAT AUG 17 2013
HELD OFF AS LONG AS WE COULD...BUT KUEX NOW INDICATES ISOLATED
SHOWER ACTIVITY DEVELOPING OVER ROOKS COUNTY. MEAGER ELEVATED
POTENTIAL INSTABILITY IS ALSO SUGGESTED BY RAP ANALYSIS PROXIMITY
SOUNDINGS AND THUS...OCCASIONAL LIGHTNING/THUNDER ALSO CANNOT BE
RULED OUT. WENT AHEAD WITH 20% POPS UNTIL 13Z FOR OUR EXTREME
SOUTHWESTERN CWA. THE LOW LEVEL JET SHOULD QUICKLY DIMINISH POST-
SUNRISE THUS ALLOWING FOR DIMINISHING SHOWER AND THUNDERSTORM
ACTIVITY. REMAINDER OF THE FORECAST WAS LEFT UNCHANGED.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 346 AM CDT SAT AUG 17 2013
OVERNIGHT MAP ANALYSIS INDICATES MID TO UPPER LEVEL LONGWAVE
RIDGING OVER THE WESTERN CONUS...WITH A TROUGH OVER THE EAST. MID
TO UPPER LEVEL JET ENERGY EXTENDS FROM THE WEST-CENTRAL
CONUS...NORTHEAST INTO SOUTHWEST AND SOUTH CENTRAL CANADA...AND
THEN SOUTHEAST ACROSS THE PLAINS...AND FINALLY EAST/NORTHEAST
ACROSS THE SOUTHEASTERN CONUS AND ON INTO THE EASTERN CONUS. MID
TO UPPER LEVEL FLOW OVER THE CENTRAL PLAINS REMAINS FROM THE
NORTH/NORTHWEST AS A RESULT...BUT IS NOT PARTICULARLY STRONG ONLY
MAXING OUT AT AROUND 45KTS NEAR 200MB PER 00Z SOUNDING DATA FROM
KLBF AND KOAX. WATER VAPOR IMAGERY ALSO SHOWS THE AFOREMENTIONED
LONGWAVE RIDGE AND TROUGH...WITH INCREASED VALUES OF MID LEVEL
MOISTURE FLOWING ALONG THE MID LEVEL JET AXIS. AT THE SURFACE A
LARGE AREA OF HIGH BAROMETRIC PRESSURE EXISTS OVER THE MISSOURI
AND MID MISSISSIPPI RIVER VALLEYS. LOW LEVEL FLOW ACROSS OUR AREA
REMAINS FROM THE SOUTHEAST AS A RESULT.
LOW LEVEL THERMAL ADVECTION ALONG THE AXIS OF A ~30KT 850MB JET
AXIS IS HELPING PROMOTE ISOLATED SHOWER AND THUNDERSTORM ACTIVITY
OVER PORTIONS OF WESTERN KANSAS THIS MORNING. ALTHOUGH THIS
ACTIVITY HAS REMAINED SOUTHWEST OF OUR CWA SO FAR
TONIGHT...GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...AND SREF-
MEAN ALL SUGGEST THE LOW LEVEL JET STREAK AXIS WILL VEER MORE INTO
OUR AREA TOWARDS 12Z. THE NAM AND EC BOTH SUGGEST LIGHT
PRECIPITATION WILL BE REALIZED OVER EXTREME SOUTHWESTERN PORTIONS
OF OUR CWA...A SOLUTION ALSO SUPPORTED TO AN EXTENT BY THE HRRR
AND 1KM WRF-NMM. ALL THAT BEING SAID...CONFIDENCE OF ANY ONE
LOCATION ACROSS OUR CWA...INCLUDING OUR SOUTHWESTERN
CWA...ACTUALLY OBSERVING MEASURABLE RAINFALL REMAINS VERY LOW AND
AS A RESULT...WILL CONTINUE WITH THE DRY FORECAST FOR EARLY THIS
MORNING AND CONTINUE TO MONITOR.
FOR THE REST OF TODAY AND TONIGHT...AN OVERALL LACK IN KINEMATIC
FORCING SHOULD PRESENT DRY CONDITIONS TO OUR AREA THROUGH TONIGHT.
MUCH LIKE THIS MORNING HOWEVER...THE ONLY EXCEPTION COULD BE
ACROSS OUR WEST/SOUTHWEST 06-12Z SUNDAY AS THE AXIS OF ~30KT 850MB
JET STREAK ONCE AGAIN DEVELOPS OVER PORTIONS OF THE CENTRAL HIGH
PLAINS. THAT BEING SAID...QPF FIELDS FROM VARIOUS MODELS DO NOT
SUGGEST MEASURABLE PRECIPITATION WILL BE REALIZED ANYWHERE ACROSS
OUR CWA AND GIVEN THIS...WILL GO AHEAD AND MAINTAIN A DRY FORECAST
THROUGH 12Z SUNDAY AND LET FUTURE SHIFTS REEVALUATE THE POTENTIAL
NEED FOR LOW POPS DURING THE EARLY MORNING HOURS ON SUNDAY.
CLOUD COVER REALLY KEPT TEMPERATURES ACROSS OUR CWA ON THE COOL
SIDE DURING THE DAY FRIDAY. THE STRATUS DECK HAS NOT BEEN NEARLY
AS DENSE AS EXPECTED TONIGHT HOWEVER AND THE CURRENT THINKING IS
THIS STRATUS SHOULD DISSIPATE AND LIFT BY MID TO LATE MORNING
WHICH SHOULD ALLOW FOR WARMER AFTERNOON HIGHS. GUIDANCE FROM THE
MET...MAV...AND ECS SEEMS TO HAVE A GOOD HANDLE ON THIS AND TAKING
AN EVEN AVERAGE OF THE THREE PROVIDES AFTERNOON HIGH TEMPERATURES
IN THE UPPER 70S TO NEAR 80 ACROSS MUCH OF THE CWA. CLEARER SKIES
SHOULD ALLOW FOR A SLIGHTLY COOLER OVERNIGHT LOWS TONIGHT WHEN
COMPARED TO EARLY THIS MORNING...WITH OVERNIGHT LOWS IN THE UPPER
50S TO NEAR 60 CURRENTLY FORECAST FOR MOST LOCATIONS TONIGHT.
FINALLY...NEAR-ZERO LOW LEVEL DEW POINT DEPRESSIONS AND A FAIRLY
LIGHT SOUTH/SOUTHEAST LOW LEVEL WIND FIELD COULD PROMOTE PATCHY
FOG ACROSS THE AREA TOWARDS SUNRISE SUNDAY. VISIBILITY RESTRICTION
IS NOT EXPECTED TO BE SIGNIFICANT...BUT WILL GO AHEAD WITH PATCHY
FOG IN THE GRIDS BEGINNING 09Z SUNDAY.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 346 AM CDT SAT AUG 17 2013
A RELATIVELY QUIET WEATHER PATTERN WILL BECOME EVIDENT BEGINNING
SUNDAY AS HIGH PRESSURE CONTINUES TO SLIDE OVER THE REGION FROM
THE INTERMOUNTAIN WEST.
WATER VAPOR IMAGERY DEPICTS A 500MB TROUGH OVER THE EASTERN PART
OF THE CONUS...WHILE HIGH PRESSURE IS BUILDING IN OVER MOST OF THE
WESTERN CONUS. THERE IS A SHORT WAVE TROUGH EVIDENT OVER THE
PACIFIC NORTHWEST AS WELL. MODELS ARE IN GOOD AGREEMENT WITH
REGARDS TO HIGH PRESSURE BUILDING IN FROM THE WEST TO CONTINUE.
THIS PATTERN WILL MAKE FOR WARMER DAYS AHEAD WITH TEMPERATURES
FORECAST TO BE MORE SEASONABLE THAN THE PREVIOUS WEEK. THE PATTERN
OVER THE NEXT WEEK IS SHOWING UNFAVORABLE CONDITIONS FOR ANY
PRECIPITATION AND HENCE A DRY FORECAST THROUGH MOST OF THE
EXTENDED AS HIGH PRESSURE DOMINATES THE REGION. THURSDAY NIGHT
INTO FRIDAY APPEARS TO BE THE ONLY DAY SHOWING ANY CHANCE FOR
PRECIPITATION...BUT THE LATEST RUNS OF THE GFS AND EC ARE BOTH
BEGINNING TO SHOW DRY CONDITIONS IN THE EXTENDED. SINCE THIS IS
THE FIRST RUN OF THE EC AND GFS AGREEING IN FAVOR OF DRIER
CONDITIONS...I WILL LEAVE THE SLIGHT CHANCES IN THERE FOR THURSDAY
NIGHT INTO FRIDAY UNTIL SOME CONSISTENCY EVOLVES. DONT WANT A FLIP
FLOP SCENARIO DEVELOPING. I CAN SEE THESE POPS GETTING YANKED IF
THIS TREND CONTINUES INTO DAY SHIFT THOUGH. SEEMS VERY REASONABLE
TO HAVE THE DRY FORECAST BASED ON THE HIGH PRESSURE STILL PROGGED
TO BE NEARLY CENTERED OVER THE CENTRAL PLAINS REGION COME FRIDAY.
WITH THE HELP OF HIGH PRESSURE BUILDING IN OVER THE
REGION...TEMPERATURES WILL BE MORE SEASONABLE THROUGH THE
EXTENDED. SUNDAY WILL BE THE COOLEST DAY OVER THE FORECAST
PERIOD...WITH HIGHS RANGING FROM THE LOWER 80S TO UPPER 80S.
MONDAY WILL BE SLIGHTLY WARMER. BUT BY TUESDAY...HIGH TEMPERATURES
NEAR 90 DEGREES WILL BE THE NORM THROUGH AT LEAST FRIDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 555 AM CDT SAT AUG 17 2013
VFR CONDITIONS FORECAST THROUGH THE NEXT 24 HOURS.
STRATUS...WHICH WAS EXPECTED TO PERSIST OVER PORTIONS OF SOUTH
CENTRAL NEBRASKA...HAS MATERIALIZED MORE OVER WESTERN NEBRASKA.
LATEST GUIDANCE SUGGESTS THIS STRATUS WILL REMAIN TO THE WEST OF
GRI BEFORE DISSIPATING LATER THIS MORNING. GIVEN THE LATEST
OBSERVATIONS FROM ACROSS THE REGION...AS WELL AS MODEL
GUIDANCE...OPTED TO GO WITH VFR CONDITIONS THROUGH THE TAF PERIOD.
THIS WILL NEED TO BE CLOSELY MONITORED THROUGH THE NEXT 3-6 HOURS
TO ENSURE THE STRATUS OUT WEST DOES NOT PUSH EAST CLOSER TO
GRI...BUT OTHERWISE VFR CONDITIONS SHOULD PERSIST AT GRI. THE
SURFACE WIND WILL REMAIN FROM THE SOUTHEAST DURING THE TAF
PERIOD...GENERALLY IN THE 6-10KT RANGE. PATCHY FOG WILL BE
POSSIBLE TOWARDS SUNRISE SUNDAY...BUT AT THIS TIME SIGNIFICANT
VISIBILITY RESTRICTION IS NOT EXPECTED AT KGRI...THUS THE P6SM
VISIBILITY FORECAST THROUGHOUT THE TAF.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...BRYANT
SHORT TERM...BRYANT
LONG TERM...GUERRERO
AVIATION...BRYANT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
230 PM EDT SAT AUG 17 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC WILL EXTEND
SOUTHWARD INTO THE PIEDMONT OF CAROLINAS THROUGH SUNDAY. MEANWHILE
WEAK WAVES OF LOW PRESSURE WILL DEVELOP AND MOVE ALONG A STALLED
FRONT ACROSS GEORGIA AND COASTAL CAROLINA.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1055 AM SATURDAY...
...CHILLY AND UNSETTLED WEATHER TODAY...
SCATTERED TO NUMEROUS PATCHES OF LIGHT RAIN AND DRIZZLE ARE NOTED ON
THE KRAX WSR-88D THIS MORNING. THE PRECIPITATION IS LARGELY BEING
DRIVEN BY MODEST LOW LEVEL ISENTROPIC LIFT WITH A FAIRLY STRONG
SOUTHWESTERLY FLOW ALOFT. THE ISENTROPIC LIFT CAN BE SEEN IN THE 12
UTC KGSO RAOB AND IN THE HMT-SEPS PROJECT VERTICAL PROFILER NEAR NEW
BERN. NWP DATA AND TRENDS IN THE NEW BERN PROFILER SUGGEST THAT THE
BEST LOW LEVEL FORCING FOR ASCENT WILL SHIFT INTO THE EASTERN
PIEDMONT AND COASTAL PLAIN DURING THE NEXT 6 HOURS AND HAVE
ACCORDINGLY INCREASED AND FOCUSED NEAR TERM POPS THERE. AFTER THIS
PERIOD THERE WILL LIKELY BE A DECREASE IN PRECIP COVERAGE ACROSS THE
SOUTHEASTERN AND EASTERN PORTIONS OF THE RAH CWA AS HIGH RES NWP
GUIDANCE...PRIMARILY RECENT RUNS OF THE HRRR AND THE 00UTC NSSL
WRF-ARW INDICATE. ANOTHER BATCH OF PRECIPITATION IS LIKELY TO PUSH
INTO THE SOUTHWESTERN AND WESTERN PIEDMONT LATE THIS AFTERNOON AND
EVENING AS ANOTHER PERTURBATION IN THE SOUTHWEST FLOW ALOFT
APPROACHES AND ENHANCES THE LOW LOW/MID-LEVEL ASCENT. WHILE RAINFALL
AMOUNTS HAVE BEEN SOMEWHAT LIGHT...THEY APPEAR SUFFICIENT TO SUSTAIN
AND LOCK IN THE COLD AIR DAMMING AIR MASS ACROSS THE PIEDMONT. BASED
ON RECENT OBSERVATIONS HAVE ADJUSTED TEMPS UP A DEGREE OR SO INTO
THE 66 TO 76 DEGREE RANGE WHICH IS MORE THAN 10 DEGREES BELOW
NORMAL. HAVE REDUCED QPF AMOUNTS A BIT TODAY GIVEN THE ISENTROPIC
LIFT APPEARS WEAKER THAN PROGGED 12 TO 36 HOURS AGO AND RADAR
AMOUNTS HAVE IN GENERAL BEEN LESS THAN EXPECT. STILL RAIN TOTALS FOR
THIS EVENT BEGINNING AT MIDNIGHT WILL LIKELY RANGE BETWEEN A QUARTER
AND A HALF INCH. -BLAES
TONIGHT...BULK OF RAIN EARLY IN THE EVENING SHOULD OCCUR ACROSS THE
NORTHERN AND WESTERN PIEDMONT AS 850MB WARM FRONT GRADUALLY PIVOTS
NORTHWEST THROUGH THIS REGION. THE WARMER AIR ALOFT OVER THE
RELATIVELY COOL SFC AIR MASS SHOULD RESULT IN AREAS OF FOG ACROSS
THE PIEDMONT OVERNIGHT ALONG WITH PATCHES OF LIGHT RAIN. RAIN
COVERAGE SHOULD BE LESS OVER THE COASTAL PLAIN AND SANDHILLS. MIN
TEMPS IN THE MID 60S NW TO NEAR 70 SE. -WSS
&&
.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
AS OF 310 AM SATURDAY...
SUNDAY AND SUNDAY NIGHT...MAIN SHEAR AXIS ALOFT MIGRATES WESTWARD TO
A POSITION OVER THE FOOTHILLS INTO THE WESTERN PIEDMONT. AIR MASS
PLENTY MOIST ENOUGH TO SUPPORT THE DEVELOPMENT OF SCATTERED-NUMEROUS
SHOWERS. FARTHER EAST...MODEL GUIDANCE HINTING AT SOME MID-UPPER
LEVEL DRYING TAKING PLACE. IF THIS WERE TO OCCUR...BREAKS IN
OVERCAST MAY DESTABILIZE THE LOW LEVEL AIR MASS ENOUGH TO GENERATE
SCATTERED SHOWERS AND A FEW THUNDERSTORMS. MODEL GUIDANCE CURRENTLY
SUGGEST INSTABILITY AS MARGINAL AT BEST THOUGH BULK SHEAR VALUES
SUFFICIENT (30-40KTS) FOR THE DEVELOPMENT OF ORGANIZED CONVECTION.
MODEL SFC DATA ALSO DEPICT A WEAK SURFACE BOUNDARY IN VICINITY OF
THE COASTAL PLAIN SUNDAY AFTERNOON-EVENING. ANY STORMS THAT FORM AND
MOVE ALONG THIS FEATURE MAY EXHIBIT SOME ROTATION. LACK OF
SUFFICIENT WIND SPEED SHOULD LIMIT SEVERE POTENTIAL.
TEMPS SUNDAY HIGHLY DEPENDENT ON ANY BREAKS IN THE OVERCAST AND
EXTENT OF SHOWER ACTIVITY. MOS GUIDANCE HINTING AT SOME RECOVERY OF
THE AIR MASS ESPECIALLY IN THE COASTAL PLAIN. FAVOR WAITING TO SEE
THE EXTENT OF RAIN COVERAGE TODAY AND DEVELOPMENT OF CAD BEFORE
RAISING TEMPS TOO MUCH ON SUNDAY. PLAN TO MAINTAIN MAX TEMPS FROM
PREVIOUS FORECAST WITH LOWER 70S NW TO THE LOWER 80S SE.
SHOWER CHANCES DWINDLE SUNDAY NIGHT AS SHEAR AXIS WEAKENS IN
RESPONSE TO RISING HEIGHTS FROM THE BUILDING SUBTROPICAL RIDGE TO
OUR EAST AND AIR MASS NOT AS SATURATED. PLAN TO MAINTAIN A CHANCE TO
SLIGHT CHANCE POPS ACROSS THE REGION (HIGHEST IN THE WEST-NW). MIN
TEMPS MID-UPPER 60S.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 310 AM SATURDAY...
MONDAY THROUGH TUESDAY NIGHT:
THE CLOSED LOW CURRENTLY OVER THE LOWER MS RIVER VALLEY IS FORECAST
TO OPEN AND LIFT TOWARDS OUR REGION THIS WEEKEND AND SLOWLY MOVE
ACROSS OUR AREA MONDAY INTO TUESDAY. THIS FEATURE ALONG WITH
ABUNDANT MOISTURE (PW`S OF AROUND 2") IN ADVANCE OF THE SYSTEM
SHOULD SET THE STAGE FOR AT LEAST SCATTERED AFTERNOON AND EVENING
SHOWERS AND STORMS ACROSS CENTRAL NC ON MONDAY AREAWIDE. TUESDAY THE
HIGHEST CONCENTRATION OF SHOWERS AND STORMS IS EXPECTED ACROSS THE
SOUTHERN/SOUTHEASTERN HALF OF CENTRAL NC AS THE SHEAR SLOWLY MOVES
ACROSS THE AREA. THUS... WE KEEP CHANCE AFTERNOON AND EVENING POPS
FOR ALL LOCATIONS MONDAY. TUESDAY WILL DO THE SAME... BUT WILL
ADVERTISE LOW CHANCE POPS ACROSS THE NORTH/NORTHWEST AS THE SHEAR
AXIS SLOWLY SHIFTS SOUTH/SOUTHEASTWARD ACROSS THE AREA ON TUESDAY...
USHERING DRY AIR ALOFT.
TEMPERATURES DURING THIS TIME FRAME WILL REBOUND AS ANY LINGERING
SURFACE BOUNDARIES ACROSS THE REGION BEGIN TO WASHOUT. HOWEVER... WE
MAY SEE THE FAR NORTHWEST PIEDMONT HANG ONTO A RESIDUAL CAD AIRMASS
FOR MOST OF THE DAY MONDAY. THUS... WILL SHOW TEMPS RANGING FROM THE
UPPER 70S TO NEAR 80 FAR NW TO UPPER 80S SE. TUESDAY EXPECTED WE
WILL SEE MID TO UPPER 80S ACROSS THE AREA. LOW TEMPS DURING THIS
TIMEFRAME WILL BE NEAR NORMAL... IN THE UPPER 60S TO LOWER 70S.
WEDNESDAY THROUGH FRIDAY:
THE LINGERING SHEAR AXIS IS EXPECTED TO EITHER REMAIN ACROSS OUR
SOUTHERN COUNTIES OR PUSH JUST TO THE SOUTH OF OUR REGION WHILE
WEAKENING ON WEDNESDAY INTO THURSDAY. THROUGH 84 HOURS BOTH THE NAM
AND GFS SHOW THIS AFOREMENTIONED SHEAR AXIS ACROSS OUR REGION IN A
ENE TO WSW FASHION... WHILE THE ECMWF IS SLOWER AND HAS THE FEATURE
BACK ACROSS THE HIGHER TERRAIN AT THIS TIME... BEFORE SETTLING THIS
FEATURE SOUTH/SOUTHEASTWARD INTO OUR AREA ON TUESDAY AFTERNOON INTO
TUESDAY NIGHT THEN LINGERING THE FEATURE ACROSS SOUTHERN PORTIONS OF
THE AREA ON WEDNESDAY. THUS... EXPECT THE BEST CHANCE OF SEEING ANY
SHOWERS AND STORMS ON WEDNESDAY WILL BE ACROSS SOUTHERN PORTIONS OF
THE AREA.
THE FORECAST BECOMES MORE UNCLEAR ON THURSDAY INTO FRIDAY... FIRST
WITH THE TRACK AN EVOLUTION OF TWO SEPARATE S/W FEATURES. THE GFS
ATTEMPTS TO BRING SOME FORM OF S/W ENERGY (POSSIBLY FROM THE
REMNANTS OF THE SYSTEM CURRENTLY LOCATION IN THE GULF OF MEXICO)
AROUND THE EXPANDING SUB-TROPICAL RIDGE ACROSS THE DEEP SOUTH AND
INTO OUR AREA ON THURSDAY INTO THURSDAY NIGHT... WHILE THE LATEST
ECMWF (12Z/16TH) HAS A WEAK S/W DROPPING SOUTHWARD OUT OF THE GREAT
LAKES ON WEDNESDAY AND MOVING ACROSS THE MID-ATLANTIC REGION LATE
THURSDAY INTO FRIDAY. GIVEN THIS AND WPC IS ADVERTISING A BETTER
CHANCE OF SHOWERS AND STORMS THAT DAY ACROSS OUR AREA WILL HOLD ONTO
CHANCE POPS FOR THURSDAY. ON FRIDAY... THE GFS AND ECMWF DIFFER WITH
REGARD TO THE NEXT APPROACHING COLD FRONT... WITH THE GFS BRINGING A
FRONT INTO THE AREA BY LATE FRIDAY... WITH THE ECMWF MUCH SLOWER.
FOR NOW WILL KEEP POPS AS IS FOR FRIDAY LOW END CHANCE/SLIGHT CHANCE
ACROSS THE AREA. TEMPS DURING THIS TIME SHOULD BE NEAR NORMAL...
UPPER 80S TO NEAR 90 FOR HIGHS WITH LOWS IN THE UPPER 60S TO LOWER
70S.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 230 PM SATURDAY...
HIGH CONFIDENCE OF ADVERSE AVIATION CONDITIONS THROUGH MOST OF THE
24 HOUR TAF PERIOD.
MULTIPLE AREAS OF RAIN AND AN ASSOCIATED COOL AND MOIST AIR MASS
WILL RESULT IN LOW CEILINGS AND REDUCED VISIBILITIES DURING THE NEXT
24 HOURS. IFR TO LIFR CONDITIONS AT THE TAF LOCATIONS THIS AFTERNOON
AREA ASSOCIATED WITH AREAS OF LIGHT TO BRIEFLY HEAVIER RAIN THAT
WILL PERSIST INTO THE EVENING. THE LARGE AREA OF SHOWERS ACROSS THE
COASTAL PLAIN AND SANDHILLS WILL GRADUALLY MOVE AWAY FROM THE AREA
THIS EVENING WITH ANOTHER BATCH OF SHOWERS MOVING INTO THE WESTERN
PIEDMONT FROM THE SOUTHWEST THIS EVENING AND PERSISTING INTO THE
OVERNIGHT HOURS. OUTSIDE OF THE LARGE AREAS OF RAIN...MORE SCATTERED
SHOWERS OR PATCHY DRIZZLE WITH AREAS OF FOG CAN BE EXPECTED.
SUNDAY WILL START OFF WITH LOW CEILINGS IN THE LIFR/IFR RANGE. BUT
SOME IMPROVEMENT IS POSSIBLE...ESPECIALLY ACROSS THE COASTAL PLAIN
NEAR KFAY AND KRWI WHERE BASES MAY LIFT TO THE HIGH END MVFR/LOW END
VFR RANGE DURING THE MID TO LATE AFTERNOON. FARTHER WEST IN THE
WESTERN PIEDMONT...LOW CEILINGS AND AREAS OF FOG/MIST WILL PERSIST
THROUGH MUCH OF THE DAY WITH IFR CONDITIONS DURING THE MORNING
SLOWLY IMPROVING TO MVFR BY AFTERNOON.
LOOKING FURTHER AHEAD...LINGERING LOW CLOUDS AND SHOWERS ARE
EXPECTED LATE SUNDAY THROUGH MONDAY...ESPECIALLY ACROSS THE INTERIOR
PIEDMONT. CONDITIONS ARE EXPECTED TO GENERALLY IMPROVE DURING THE
MID TO LATE WEEK PERIOD. MAINLY SCATTERED AFTERNOON OR EVENING
CONVECTION IS POSSIBLE...ESPECIALLY ACROSS THE SOUTHERN PORTIONS OF
THE FORECAST AREA. -BLAES
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...BLAES/WSS
SHORT TERM...WSS
LONG TERM...BSD
AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1055 AM EDT SAT AUG 17 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC WILL EXTEND
SOUTHWARD INTO THE PIEDMONT OF CAROLINAS THROUGH SUNDAY. MEANWHILE
WEAK WAVES OF LOW PRESSURE WILL DEVELOP AND MOVE ALONG A STALLED
FRONT ACROSS GEORGIA AND COASTAL CAROLINA.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1055 AM SATURDAY...
...CHILLY AND UNSETTLED WEATHER TODAY...
SCATTERED TO NUMEROUS PATCHES OF LIGHT RAIN AND DRIZZLE ARE NOTED ON
THE KRAX WSR-88D THIS MORNING. THE PRECIPITATION IS LARGELY BEING
DRIVEN BY MODEST LOW LEVEL ISENTROPIC LIFT WITH A FAIRLY STRONG
SOUTHWESTERLY FLOW ALOFT. THE ISENTROPIC LIFT CAN BE SEEN IN THE 12
UTC KGSO RAOB AND IN THE HMT-SEPS PROJECT VERTICAL PROFILER NEAR NEW
BERN. NWP DATA AND TRENDS IN THE NEW BERN PROFILER SUGGEST THAT THE
BEST LOW LEVEL FORCING FOR ASCENT WILL SHIFT INTO THE EASTERN
PIEDMONT AND COASTAL PLAIN DURING THE NEXT 6 HOURS AND HAVE
ACCORDINGLY INCREASED AND FOCUSED NEAR TERM POPS THERE. AFTER THIS
PERIOD THERE WILL LIKELY BE A DECREASE IN PRECIP COVERAGE ACROSS THE
SOUTHEASTERN AND EASTERN PORTIONS OF THE RAH CWA AS HIGH RES NWP
GUIDANCE...PRIMARILY RECENT RUNS OF THE HRRR AND THE 00UTC NSSL
WRF-ARW INDICATE. ANOTHER BATCH OF PRECIPITATION IS LIKELY TO PUSH
INTO THE SOUTHWESTERN AND WESTERN PIEDMONT LATE THIS AFTERNOON AND
EVENING AS ANOTHER PERTURBATION IN THE SOUTHWEST FLOW ALOFT
APPROACHES AND ENHANCES THE LOW LOW/MID-LEVEL ASCENT. WHILE RAINFALL
AMOUNTS HAVE BEEN SOMEWHAT LIGHT...THEY APPEAR SUFFICIENT TO SUSTAIN
AND LOCK IN THE COLD AIR DAMMING AIR MASS ACROSS THE PIEDMONT. BASED
ON RECENT OBSERVATIONS HAVE ADJUSTED TEMPS UP A DEGREE OR SO INTO
THE 66 TO 76 DEGREE RANGE WHICH IS MORE THAN 10 DEGREES BELOW
NORMAL. HAVE REDUCED QPF AMOUNTS A BIT TODAY GIVEN THE ISENTROPIC
LIFT APPEARS WEAKER THAN PROGGED 12 TO 36 HOURS AGO AND RADAR
AMOUNTS HAVE IN GENERAL BEEN LESS THAN EXPECT. STILL RAIN TOTALS FOR
THIS EVENT BEGINNING AT MIDNIGHT WILL LIKELY RANGE BETWEEN A QUARTER
AND A HALF INCH. -BLAES
TONIGHT...BULK OF RAIN EARLY IN THE EVENING SHOULD OCCUR ACROSS THE
NORTHERN AND WESTERN PIEDMONT AS 850MB WARM FRONT GRADUALLY PIVOTS
NORTHWEST THROUGH THIS REGION. THE WARMER AIR ALOFT OVER THE
RELATIVELY COOL SFC AIR MASS SHOULD RESULT IN AREAS OF FOG ACROSS
THE PIEDMONT OVERNIGHT ALONG WITH PATCHES OF LIGHT RAIN. RAIN
COVERAGE SHOULD BE LESS OVER THE COASTAL PLAIN AND SANDHILLS. MIN
TEMPS IN THE MID 60S NW TO NEAR 70 SE. -WSS
&&
.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
AS OF 310 AM SATURDAY...
SUNDAY AND SUNDAY NIGHT...MAIN SHEAR AXIS ALOFT MIGRATES WESTWARD TO
A POSITION OVER THE FOOTHILLS INTO THE WESTERN PIEDMONT. AIR MASS
PLENTY MOIST ENOUGH TO SUPPORT THE DEVELOPMENT OF SCATTERED-NUMEROUS
SHOWERS. FARTHER EAST...MODEL GUIDANCE HINTING AT SOME MID-UPPER
LEVEL DRYING TAKING PLACE. IF THIS WERE TO OCCUR...BREAKS IN
OVERCAST MAY DESTABILIZE THE LOW LEVEL AIR MASS ENOUGH TO GENERATE
SCATTERED SHOWERS AND A FEW THUNDERSTORMS. MODEL GUIDANCE CURRENTLY
SUGGEST INSTABILITY AS MARGINAL AT BEST THOUGH BULK SHEAR VALUES
SUFFICIENT (30-40KTS) FOR THE DEVELOPMENT OF ORGANIZED CONVECTION.
MODEL SFC DATA ALSO DEPICT A WEAK SURFACE BOUNDARY IN VICINITY OF
THE COASTAL PLAIN SUNDAY AFTERNOON-EVENING. ANY STORMS THAT FORM AND
MOVE ALONG THIS FEATURE MAY EXHIBIT SOME ROTATION. LACK OF
SUFFICIENT WIND SPEED SHOULD LIMIT SEVERE POTENTIAL.
TEMPS SUNDAY HIGHLY DEPENDENT ON ANY BREAKS IN THE OVERCAST AND
EXTENT OF SHOWER ACTIVITY. MOS GUIDANCE HINTING AT SOME RECOVERY OF
THE AIR MASS ESPECIALLY IN THE COASTAL PLAIN. FAVOR WAITING TO SEE
THE EXTENT OF RAIN COVERAGE TODAY AND DEVELOPMENT OF CAD BEFORE
RAISING TEMPS TOO MUCH ON SUNDAY. PLAN TO MAINTAIN MAX TEMPS FROM
PREVIOUS FORECAST WITH LOWER 70S NW TO THE LOWER 80S SE.
SHOWER CHANCES DWINDLE SUNDAY NIGHT AS SHEAR AXIS WEAKENS IN
RESPONSE TO RISING HEIGHTS FROM THE BUILDING SUBTROPICAL RIDGE TO
OUR EAST AND AIR MASS NOT AS SATURATED. PLAN TO MAINTAIN A CHANCE TO
SLIGHT CHANCE POPS ACROSS THE REGION (HIGHEST IN THE WEST-NW). MIN
TEMPS MID-UPPER 60S.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 310 AM SATURDAY...
MONDAY THROUGH TUESDAY NIGHT:
THE CLOSED LOW CURRENTLY OVER THE LOWER MS RIVER VALLEY IS FORECAST
TO OPEN AND LIFT TOWARDS OUR REGION THIS WEEKEND AND SLOWLY MOVE
ACROSS OUR AREA MONDAY INTO TUESDAY. THIS FEATURE ALONG WITH
ABUNDANT MOISTURE (PW`S OF AROUND 2") IN ADVANCE OF THE SYSTEM
SHOULD SET THE STAGE FOR AT LEAST SCATTERED AFTERNOON AND EVENING
SHOWERS AND STORMS ACROSS CENTRAL NC ON MONDAY AREAWIDE. TUESDAY THE
HIGHEST CONCENTRATION OF SHOWERS AND STORMS IS EXPECTED ACROSS THE
SOUTHERN/SOUTHEASTERN HALF OF CENTRAL NC AS THE SHEAR SLOWLY MOVES
ACROSS THE AREA. THUS... WE KEEP CHANCE AFTERNOON AND EVENING POPS
FOR ALL LOCATIONS MONDAY. TUESDAY WILL DO THE SAME... BUT WILL
ADVERTISE LOW CHANCE POPS ACROSS THE NORTH/NORTHWEST AS THE SHEAR
AXIS SLOWLY SHIFTS SOUTH/SOUTHEASTWARD ACROSS THE AREA ON TUESDAY...
USHERING DRY AIR ALOFT.
TEMPERATURES DURING THIS TIME FRAME WILL REBOUND AS ANY LINGERING
SURFACE BOUNDARIES ACROSS THE REGION BEGIN TO WASHOUT. HOWEVER... WE
MAY SEE THE FAR NORTHWEST PIEDMONT HANG ONTO A RESIDUAL CAD AIRMASS
FOR MOST OF THE DAY MONDAY. THUS... WILL SHOW TEMPS RANGING FROM THE
UPPER 70S TO NEAR 80 FAR NW TO UPPER 80S SE. TUESDAY EXPECTED WE
WILL SEE MID TO UPPER 80S ACROSS THE AREA. LOW TEMPS DURING THIS
TIMEFRAME WILL BE NEAR NORMAL... IN THE UPPER 60S TO LOWER 70S.
WEDNESDAY THROUGH FRIDAY:
THE LINGERING SHEAR AXIS IS EXPECTED TO EITHER REMAIN ACROSS OUR
SOUTHERN COUNTIES OR PUSH JUST TO THE SOUTH OF OUR REGION WHILE
WEAKENING ON WEDNESDAY INTO THURSDAY. THROUGH 84 HOURS BOTH THE NAM
AND GFS SHOW THIS AFOREMENTIONED SHEAR AXIS ACROSS OUR REGION IN A
ENE TO WSW FASHION... WHILE THE ECMWF IS SLOWER AND HAS THE FEATURE
BACK ACROSS THE HIGHER TERRAIN AT THIS TIME... BEFORE SETTLING THIS
FEATURE SOUTH/SOUTHEASTWARD INTO OUR AREA ON TUESDAY AFTERNOON INTO
TUESDAY NIGHT THEN LINGERING THE FEATURE ACROSS SOUTHERN PORTIONS OF
THE AREA ON WEDNESDAY. THUS... EXPECT THE BEST CHANCE OF SEEING ANY
SHOWERS AND STORMS ON WEDNESDAY WILL BE ACROSS SOUTHERN PORTIONS OF
THE AREA.
THE FORECAST BECOMES MORE UNCLEAR ON THURSDAY INTO FRIDAY... FIRST
WITH THE TRACK AN EVOLUTION OF TWO SEPARATE S/W FEATURES. THE GFS
ATTEMPTS TO BRING SOME FORM OF S/W ENERGY (POSSIBLY FROM THE
REMNANTS OF THE SYSTEM CURRENTLY LOCATION IN THE GULF OF MEXICO)
AROUND THE EXPANDING SUB-TROPICAL RIDGE ACROSS THE DEEP SOUTH AND
INTO OUR AREA ON THURSDAY INTO THURSDAY NIGHT... WHILE THE LATEST
ECMWF (12Z/16TH) HAS A WEAK S/W DROPPING SOUTHWARD OUT OF THE GREAT
LAKES ON WEDNESDAY AND MOVING ACROSS THE MID-ATLANTIC REGION LATE
THURSDAY INTO FRIDAY. GIVEN THIS AND WPC IS ADVERTISING A BETTER
CHANCE OF SHOWERS AND STORMS THAT DAY ACROSS OUR AREA WILL HOLD ONTO
CHANCE POPS FOR THURSDAY. ON FRIDAY... THE GFS AND ECMWF DIFFER WITH
REGARD TO THE NEXT APPROACHING COLD FRONT... WITH THE GFS BRINGING A
FRONT INTO THE AREA BY LATE FRIDAY... WITH THE ECMWF MUCH SLOWER.
FOR NOW WILL KEEP POPS AS IS FOR FRIDAY LOW END CHANCE/SLIGHT CHANCE
ACROSS THE AREA. TEMPS DURING THIS TIME SHOULD BE NEAR NORMAL...
UPPER 80S TO NEAR 90 FOR HIGHS WITH LOWS IN THE UPPER 60S TO LOWER
70S.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 655 AM SATURDAY...
WARM MOIST AIR BEING LIFTED OVER THE COOL DRY STABLE AIR MASS AT THE
SURFACE HAS CAUSED LOW CLOUDS AND AREAS OF RAIN TO DEVELOP ACROSS
CENTRAL NC SINCE 09Z. WIDESPREAD MVFR CEILINGS EXPECTED BY MID-LATE
MORNING ACROSS ALL OF CENTRAL NC WITH POCKETS OF IFR CEILING
PROBABLE THIS AFTERNOON. THE LIKELIHOOD OF IFR CEILINGS BY DUSK
APPEARS TO BE A GOOD BET WITH PATCHES OF RAIN PERSISTING WELL INTO
THE EVENING HOURS BEFORE AREAS OF DRIZZLE AND FOG LIMIT THE
VISIBILITY.
SUNDAY WILL START OUT WITH LOW CEILINGS IN THE LIFR/IFR RANGE. BY
AFTERNOON...COULD SEE SOME IMPROVEMENT...ESPECIALLY IN VICINITY OF
KFAY AND KRWI WHERE BASES MAY LIFT TO THE HIGH END MVFR/LOW END VFR
BY MID-LATE AFTERNOON. FARTHER WEST...CEILINGS WILL LIKELY BE IN THE
MVFR CATEGORY ALL DAY ALONG WITH SPOTTY LIGHT RAIN OR RAIN SHOWERS.
AFTERNOON HEATING MAY TRIGGER AN ISOLATED THUNDERSTORM OR TWO IN THE
COASTAL PLAIN.
MVFR CONDITIONS DUE TO CEILINGS WILL PERSIST SUNDAY NIGHT INTO EARLY
MONDAY WITH A PERIOD OF IFR CEILINGS HIGHLY PROBABLY. HEATING SHOULD
RAISE CLOUD BASES TO THE HIGH END MVFR IN THE TRIAD WITH LOW END VFR
BASES ANTICIPATED ELSEWHERE. ADDITIONAL HEATING OF THE MOIST AIR
MASS SHOULD TRIGGER SCATTERED CONVECTION...MAINLY IN THE SANDHILLS
AND COASTAL PLAIN MONDAY AFTERNOON...DIMINISHING MONDAY EVENING.
AVIATION WEATHER CONDITIONS WILL GRADUALLY IMPROVE TUESDAY AND
WEDNESDAY. WHILE PERIODS OF MVFR CEILINGS STILL ANTICIPATED DURING
THE OVERNIGHT INTO THE EARLY MORNING HOURS...PERIODS OF VFR
CONDITIONS WILL LENGTHEN IN DURATION. SCATTERED AFTERNOON-EARLY
EVENING CONVECTION IS ALSO PROBABLE.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...BLAES/WSS
SHORT TERM...WSS
LONG TERM...BSD
AVIATION...WSS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1007 AM EDT SAT AUG 17 2013
.SYNOPSIS...
COOL AND WET WEATHER WILL CONTINUE FOR MUCH OF THE WEEKEND AS DEEP
TROPICAL MOISTURE STREAMS NORTHWARD ALONG A FRONTAL BOUNDARY.
CONDITIONS MORE TYPICAL OF LATE AUGUST WILL DEVELOP NEXT WEEK
AS THE FRONT SLOWLY DISSIPATES AND BERMUDA HIGH PRESSURE BECOMES THE
MAIN INFLUENCE ON OUR WEATHER.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 10 AM SATURDAY...A FRONT REMAINS POSITIONED OFFSHORE.
UNSEASONABLY COOL TEMPERATURES ARE EXPECTED AGAIN TODAY AS CLOUDS
BLANKET THE FORECAST AREA FOR MOST OF THE DAY. HIGHS ARE ONLY
EXPECTED TO REACH THE MID AND UPPER 70S.
A LARGE AREA OF SHOWERS AND A FEW THUNDERSTORMS...COINCIDENT WITH A
WAVE OF LOW PRESSURE MOVING UP A STALLED OFFSHORE FRONT...WAS
PROGRESSING TO THE NORTHEAST LATE THIS MORNING. THE BRUNT OF THIS
CONVECTION WILL MOVE ACROSS THE WATERS AND OFFSHORE THROUGH THE
AFTERNOON. HOWEVER...THE WESTERN FRINGES OF THIS ACTIVITY WILL SKIRT
THE COAST AS THE AREA EXPANDS...ESPECIALLY THE CAPE FEAR AREA.
THUS...FOR THE NEXT SEVERAL HOURS...EXPECT THE COVERAGE OF SHOWERS
TO INCREASE...ESPECIALLY ALONG AND EAST OF A LINE FROM CRE TO CPC
AND EYF. A THUNDERSTORM CAN NOT BE RULED OUT ALTHOUGH MOST OF THE
THUNDERSTORM ACTIVITY IS EXPECTED TO REMAIN ON THE WARM SIDE OF THE
OFFSHORE FRONT. DEVELOPING SUBSIDENCE DOWNSTREAM OF THIS ACTIVITY IS
EXPECTED TO HELP SQUELCH CONVECTION WEST OF THE AFOREMENTIONED LINE
FOR THE NEXT SEVERAL HOURS. WILL SHOW POPS EVENTUALLY TRENDING
HIGHER IN THESE AREAS DURING THE AFTERNOON.
A SERIES OF WAVES MOVING ALONG THE FRONT AND INDUCED BY UPPER LEVEL
DISTURBANCES RIDING UP THE LEADING EDGE OF AN UNSEASONABLY DEEP H/5
EAST COAST TROUGH WILL KEEP THE WEATHER UNSETTLED. OVERRUNNING
PATTERN IN PLACE FOR THE PAST FEW DAYS STILL VERY EVIDENT...WITH A
DEEP TROPICALLY-SOURCED AIRMASS OVERRIDING A RELATIVELY COOL AND
MOIST EASTERLY FLOW CLOSER TO THE SURFACE.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 315 AM SATURDAY...THE FA WILL LIE IN BETWEEN THE WESTERN
ATLANTIC RIDGE AND THE CUTOFF LOW ACROSS THE CENTRAL MISSISSIPPI
VALLEY. AMPLE SUPPLY OF MOISTURE ACROSS THE FA...AS FEEDS FROM BOTH
THE ATLANTIC AT THE LOW LEVELS...AND THE GULF OF MEXICO MID AND
UPPER LEVELS...ADVECT ACROSS THE FA. WEAK AREA OF LOW PRESSURE IS
PROGGED BY THE MODELS TO TRAVEL ALONG A COASTAL TROF/FRONT ORIENTED
NE-SW OVER THE ATLANTIC WATERS..AND PARALLEL TO THE CAROLINA COASTS.
THE LOW DEPARTS TO THE NE OFF THE DELMARVA COAST BY DAYBREAK MONDAY.
UPSTAIRS...THE CUTOFF LOW ACROSS THE CENTRAL PART OF THE U.S. OPENS
UP INTO A PROGRESSIVE POSITIVELY TILTED S/W TROF WHICH REACHES THE
NE AND MID-ATLANTIC STATES LATE MONDAY NIGHT. AT THE SFC ON
SUNDAY...WEAK HIGH PRESSURE IS PROGGED TO AFFECT THE FA. ONE WOULD
THINK THAT WE ARE SAFE FROM ANY PCPN OCCURRENCE ON MONDAY.
HOWEVER...MOISTURE REMAINS IN ABUNDANCE ACROSS THE FA. WEAK 5H
VORTICIES ARE PROGGED TO PUSH ACROSS THE FA MONDAY INTO MONDAY
NIGHT. IN ADDITION...ANY AMOUNT OF INSOLATION EITHER DAY WILL RESULT
IN FURTHER DESTABILIZATION OF THE ATM LOCALLY. AS A RESULT OF ALL
THIS SAID...POPS SUNDAY AND MONDAY WILL BE IN THE MODERATE TO HIGH
CHANCE CATEGORY. THIS IS IN GOOD AGREEMENT WITH BOTH THE NAM AND GFS
MOS GUIDANCE. FOR MAX TEMPS...LEANED TOWARD THE SLIGHTLY HIGHER NAM
MOS GUIDANCE WHEN COMPARED TO THE GFS. AS FOR LOWS...BOTH MODEL MOS
GUIDANCE QUITE SIMILAR AND SEE NO REASON TO DETOUR FROM THEIR
OUTPUT. THE LATEST HPC 48 HR GUIDANCE FOR RAINFALL ACROSS THE ILM
CWA...INDICATES BETWEEN 1 TO 2 INCHES POSSIBLE. AT THIS POINT A
FLOOD WATCH IS NOT RECOMMENDED...BUT AS GROUNDS FURTHER BECOME
SATURATED...WILL HAVE TO RE-VISIT THIS ISSUE ONCE AGAIN IF HPC
FUTURE PCPN FORECASTS COME IN AT MODEST TO HIGH LEVELS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 315 AM SATURDAY...THE OPENED UP UPPER TROF WILL JUST BECOME A
MEMORY AS ITS IS ABSORBED WITHIN THE MAIN BELT OF THE UPPER
WESTERLIES. WITH NW FLOW ALOFT...THIN BAND OF MOISTURE...HAVING BEEN
STRETCHED APART WILL DROP SE-WARD...AND CROSS THE FA DURING
WEDNESDAY. BEWARE THE NW FLOW...AN ADAGE THAT HAS COME TO LIGHT WHEN
DEALING WITH CONVECTION DROPPING SE-WARD FROM UPSTREAM. A MCC OR MCS
USUALLY IS THE CULPRIT WITH THIS TYPE MID/UPPER LEVEL FLOW. CHANCE
POPS WILL CONTINUE FOR TUE AND WED. BY THU AND FRI...MODELS DIVERGE
FROM ONE ANOTHER WITH THEIR OWN RESPECTIVE SOLUTIONS DEALING WITH
THE RE-TURN OF MOISTURE AND INCREASING POPS. REMAINED RATHER
SOMEWHAT LOW-KEY WITH POPS THIS LATE IN THE TIME PERIOD DUE TO THE
UNCERTAINTY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 12Z...CEILINGS THIS MORNING WILL BE PREDOMINATELY IFR...
HOWEVER THEY WILL PROBABLY BOUNCE IN AND OUT OF MVFR...PARTICULARLY
AFTER 15Z. THE HRRR MODEL HAS A SURFACE LOW OFFSHORE THAT WILL MOVE
SLOWLY NORTHEAST THROUGH THE DAY. THE MODEL IS NOT ALL THAT ENTHUSED
WITH THE PRECIP TODAY...WITH MAINLY ONLY SCATTERED ACTIVITY. BASED
ON THE CURRENT RADAR...THIS SCENARIO SEEMS REASONABLE. VISIBILITIES
IN THE RAIN COULD LOWER TO IFR...BUT PREDOMINATELY MVFR. WINDS ARE A
BIT MORE NORTHERLY THAN PREVIOUSLY THOUGHT...PARTICULARLY INLAND ON
THE BACK SIDE OF THE SURFACE LOW. LOOK FOR THE WINDS TO SHIFT MORE
NORTHWESTERLY AS THE LOW EXITS THE REGION THIS AFTERNOON.
EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 10 AM SATURDAY...A FRONT REMAINS STALLED OFFSHORE LATE THIS
MORNING. THIS FRONT IS EXPECTED TO MOVE BACK ACROSS THE WATERS AS
WAVES OF LOW PRESSURE MOVE UP ALONG THE BOUNDARY. THUS EASTERLY
WINDS ARE EXPECTED TO VEER TO A MORE SOUTHERLY DIRECTION THROUGH THE
AFTERNOON AND THEN TO SOUTHWEST FOR A TIME. WINDS WILL VEER TO W OR
NW TONIGHT AS A WAVE OF LOW PRESSURE CLOSES OFF AND MOVES TO OUR N.
WIND SPEEDS WILL GENERALLY BE AROUND 10 KT OR LESS. SEAS OF 2 TO 3
FT WILL PERSIST. NUMEROUS TO WIDESPREAD SHOWERS AND ISOLATED
THUNDERSTORMS WILL RESULT IN POOR VISIBILITIES INTO TONIGHT.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE WESTERN ATLANTIC UPPER RIDGE AXIS IS
PROGGED TO EXTEND FURTHER WESTWARD...PUSHING THE MAIN MOISTURE
PLUME ORIENTED NE-SW FURTHER INLAND. THIS WILL POSSIBLY
PROVIDE SOME DRYING CONDITIONS FOR MARINERS TRAVERSING THE LOCAL
AND OFFSHORE WATERS LATER SUNDAY INTO MONDAY. AN EXITING SFC LOW
TO THE NE ALONG A COASTAL FRONT WILL HIGHLIGHT SUNDAY...FOLLOWED
BY WEAK HIGH PRESSURE ACROSS THE AREA FOR MONDAY. THE SFC PRESSURE
GRADIENT WILL TIGHTEST AT THE BEGINNING OF THE SHORT TERM
RELATIVELY SPEAKING...THEN RELAX THROUGH MONDAY AS HIGH PRESSURE
BECOMES DOMINATE WX FEATURE. FOR SIGNIFICANT SEAS...AN ESE GROUND
SWELL AT 9 SECOND PERIODS TO APPROACH THE LOCAL WATERS
SUNDAY...AND AFFECT THE WATERS LATE SUNDAY NIGHT THROUGH MONDAY.
EXPECT WIND DRIVEN WAVES AT 4 TO 6 SECOND PERIODS WILL DOMINATE AT
THE START...BUT EVEN OUT ONCE THE SWELL TRAVERSES THE WATERS. 2 TO
3 FT...LIKELY HIGHER ONCE THE SWELL PUSHES ACROSS THE WATERS. LATEST
WAVEWATCH3 ILLUSTRATES THIS OCCURRENCE.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 330 AM SATURDAY...THIS PERIOD WILL BE HIGHLIGHTED BY
SUPPRESSED UPPER RIDGING TO THE SOUTH WITH WEAK HIGH PRESSURE
SPORADICALLY COVERING THE SE STATES. OVERALL WINDS WILL BE
LIGHT...LESS THAN 10 KT. PREVAILING WIND DIRECTION WILL BE
SOMEWHAT DIFFICULT TO FORECAST...COULD ALMOST GO WITH A VARIABLE
DIRECTION AT TIMES. SIGNIFICANT SEAS WILL DROP TO AROUND 2 FT BY
WED AS THE DECAYING ESE SWELL GIVES WAY TO LOCALLY PRODUCED WIND
DRIVEN WAVES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...RJD
SHORT TERM...DCH
LONG TERM...DCH
AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1059 AM EDT SAT AUG 17 2013
.SYNOPSIS...
COOL AND WET WEATHER WILL CONTINUE FOR MUCH OF THE WEEKEND AS DEEP
TROPICAL MOISTURE STREAMS NORTHWARD ALONG A FRONTAL BOUNDARY.
CONDITIONS MORE TYPICAL OF LATE AUGUST WILL DEVELOP NEXT WEEK
AS THE FRONT SLOWLY DISSIPATES AND BERMUDA HIGH PRESSURE BECOMES THE
MAIN INFLUENCE ON OUR WEATHER.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 10 AM SATURDAY...A FRONT REMAINS POSITIONED OFFSHORE.
UNSEASONABLY COOL TEMPERATURES ARE EXPECTED AGAIN TODAY AS CLOUDS
BLANKET THE FORECAST AREA FOR MOST OF THE DAY. HIGHS ARE ONLY
EXPECTED TO REACH THE MID AND UPPER 70S.
A LARGE AREA OF SHOWERS AND A FEW THUNDERSTORMS...COINCIDENT WITH A
WAVE OF LOW PRESSURE MOVING UP A STALLED OFFSHORE FRONT...WAS
PROGRESSING TO THE NORTHEAST LATE THIS MORNING. THE BRUNT OF THIS
CONVECTION WILL MOVE ACROSS THE WATERS AND OFFSHORE THROUGH THE
AFTERNOON. HOWEVER...THE WESTERN FRINGES OF THIS ACTIVITY WILL SKIRT
THE COAST AS THE AREA EXPANDS...ESPECIALLY THE CAPE FEAR AREA.
THUS...FOR THE NEXT SEVERAL HOURS...EXPECT THE COVERAGE OF SHOWERS
TO INCREASE...ESPECIALLY ALONG AND EAST OF A LINE FROM CRE TO CPC
AND EYF. A THUNDERSTORM CAN NOT BE RULED OUT ALTHOUGH MOST OF THE
THUNDERSTORM ACTIVITY IS EXPECTED TO REMAIN ON THE WARM SIDE OF THE
OFFSHORE FRONT. DEVELOPING SUBSIDENCE DOWNSTREAM OF THIS ACTIVITY IS
EXPECTED TO HELP SQUELCH CONVECTION WEST OF THE AFOREMENTIONED LINE
FOR THE NEXT SEVERAL HOURS. WILL SHOW POPS EVENTUALLY TRENDING
HIGHER IN THESE AREAS DURING THE AFTERNOON.
A SERIES OF WAVES MOVING ALONG THE FRONT AND INDUCED BY UPPER LEVEL
DISTURBANCES RIDING UP THE LEADING EDGE OF AN UNSEASONABLY DEEP H/5
EAST COAST TROUGH WILL KEEP THE WEATHER UNSETTLED. OVERRUNNING
PATTERN IN PLACE FOR THE PAST FEW DAYS STILL VERY EVIDENT...WITH A
DEEP TROPICALLY-SOURCED AIRMASS OVERRIDING A RELATIVELY COOL AND
MOIST EASTERLY FLOW CLOSER TO THE SURFACE.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 315 AM SATURDAY...THE FA WILL LIE IN BETWEEN THE WESTERN
ATLANTIC RIDGE AND THE CUTOFF LOW ACROSS THE CENTRAL MISSISSIPPI
VALLEY. AMPLE SUPPLY OF MOISTURE ACROSS THE FA...AS FEEDS FROM BOTH
THE ATLANTIC AT THE LOW LEVELS...AND THE GULF OF MEXICO MID AND
UPPER LEVELS...ADVECT ACROSS THE FA. WEAK AREA OF LOW PRESSURE IS
PROGGED BY THE MODELS TO TRAVEL ALONG A COASTAL TROF/FRONT ORIENTED
NE-SW OVER THE ATLANTIC WATERS..AND PARALLEL TO THE CAROLINA COASTS.
THE LOW DEPARTS TO THE NE OFF THE DELMARVA COAST BY DAYBREAK MONDAY.
UPSTAIRS...THE CUTOFF LOW ACROSS THE CENTRAL PART OF THE U.S. OPENS
UP INTO A PROGRESSIVE POSITIVELY TILTED S/W TROF WHICH REACHES THE
NE AND MID-ATLANTIC STATES LATE MONDAY NIGHT. AT THE SFC ON
SUNDAY...WEAK HIGH PRESSURE IS PROGGED TO AFFECT THE FA. ONE WOULD
THINK THAT WE ARE SAFE FROM ANY PCPN OCCURRENCE ON MONDAY.
HOWEVER...MOISTURE REMAINS IN ABUNDANCE ACROSS THE FA. WEAK 5H
VORTICIES ARE PROGGED TO PUSH ACROSS THE FA MONDAY INTO MONDAY
NIGHT. IN ADDITION...ANY AMOUNT OF INSOLATION EITHER DAY WILL RESULT
IN FURTHER DESTABILIZATION OF THE ATM LOCALLY. AS A RESULT OF ALL
THIS SAID...POPS SUNDAY AND MONDAY WILL BE IN THE MODERATE TO HIGH
CHANCE CATEGORY. THIS IS IN GOOD AGREEMENT WITH BOTH THE NAM AND GFS
MOS GUIDANCE. FOR MAX TEMPS...LEANED TOWARD THE SLIGHTLY HIGHER NAM
MOS GUIDANCE WHEN COMPARED TO THE GFS. AS FOR LOWS...BOTH MODEL MOS
GUIDANCE QUITE SIMILAR AND SEE NO REASON TO DETOUR FROM THEIR
OUTPUT. THE LATEST HPC 48 HR GUIDANCE FOR RAINFALL ACROSS THE ILM
CWA...INDICATES BETWEEN 1 TO 2 INCHES POSSIBLE. AT THIS POINT A
FLOOD WATCH IS NOT RECOMMENDED...BUT AS GROUNDS FURTHER BECOME
SATURATED...WILL HAVE TO RE-VISIT THIS ISSUE ONCE AGAIN IF HPC
FUTURE PCPN FORECASTS COME IN AT MODEST TO HIGH LEVELS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 315 AM SATURDAY...THE OPENED UP UPPER TROF WILL JUST BECOME A
MEMORY AS ITS IS ABSORBED WITHIN THE MAIN BELT OF THE UPPER
WESTERLIES. WITH NW FLOW ALOFT...THIN BAND OF MOISTURE...HAVING BEEN
STRETCHED APART WILL DROP SE-WARD...AND CROSS THE FA DURING
WEDNESDAY. BEWARE THE NW FLOW...AN ADAGE THAT HAS COME TO LIGHT WHEN
DEALING WITH CONVECTION DROPPING SE-WARD FROM UPSTREAM. A MCC OR MCS
USUALLY IS THE CULPRIT WITH THIS TYPE MID/UPPER LEVEL FLOW. CHANCE
POPS WILL CONTINUE FOR TUE AND WED. BY THU AND FRI...MODELS DIVERGE
FROM ONE ANOTHER WITH THEIR OWN RESPECTIVE SOLUTIONS DEALING WITH
THE RE-TURN OF MOISTURE AND INCREASING POPS. REMAINED RATHER
SOMEWHAT LOW-KEY WITH POPS THIS LATE IN THE TIME PERIOD DUE TO THE
UNCERTAINTY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 12Z...CEILINGS THIS MORNING WILL BE PREDOMINATELY IFR...
HOWEVER THEY WILL PROBABLY BOUNCE IN AND OUT OF MVFR...PARTICULARLY
AFTER 15Z. THE HRRR MODEL HAS A SURFACE LOW OFFSHORE THAT WILL MOVE
SLOWLY NORTHEAST THROUGH THE DAY. THE MODEL IS NOT ALL THAT ENTHUSED
WITH THE PRECIP TODAY...WITH MAINLY ONLY SCATTERED ACTIVITY. BASED
ON THE CURRENT RADAR...THIS SCENARIO SEEMS REASONABLE. VISIBILITIES
IN THE RAIN COULD LOWER TO IFR...BUT PREDOMINATELY MVFR. WINDS ARE A
BIT MORE NORTHERLY THAN PREVIOUSLY THOUGHT...PARTICULARLY INLAND ON
THE BACK SIDE OF THE SURFACE LOW. LOOK FOR THE WINDS TO SHIFT MORE
NORTHWESTERLY AS THE LOW EXITS THE REGION THIS AFTERNOON.
EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 10 AM SATURDAY...A FRONT REMAINS STALLED OFFSHORE LATE THIS
MORNING. THIS FRONT IS EXPECTED TO MOVE BACK ACROSS THE WATERS AS
WAVES OF LOW PRESSURE MOVE UP ALONG THE BOUNDARY. THUS EASTERLY
WINDS ARE EXPECTED TO VEER TO A MORE SOUTHERLY DIRECTION THROUGH THE
AFTERNOON AND THEN TO SOUTHWEST FOR A TIME. WINDS WILL VEER TO W OR
NW TONIGHT AS A WAVE OF LOW PRESSURE CLOSES OFF AND MOVES TO OUR N.
WIND SPEEDS WILL GENERALLY BE AROUND 10 KT OR LESS. SEAS OF 2 TO 3
FT WILL PERSIST. NUMEROUS TO WIDESPREAD SHOWERS AND ISOLATED
THUNDERSTORMS WILL RESULT IN POOR VISIBILITIES INTO TONIGHT.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE WESTERN ATLANTIC UPPER RIDGE AXIS IS
PROGGED TO EXTEND FURTHER WESTWARD...PUSHING THE MAIN MOISTURE
PLUME ORIENTED NE-SW FURTHER INLAND. THIS WILL POSSIBLY
PROVIDE SOME DRYING CONDITIONS FOR MARINERS TRAVERSING THE LOCAL
AND OFFSHORE WATERS LATER SUNDAY INTO MONDAY. AN EXITING SFC LOW
TO THE NE ALONG A COASTAL FRONT WILL HIGHLIGHT SUNDAY...FOLLOWED
BY WEAK HIGH PRESSURE ACROSS THE AREA FOR MONDAY. THE SFC PRESSURE
GRADIENT WILL TIGHTEST AT THE BEGINNING OF THE SHORT TERM
RELATIVELY SPEAKING...THEN RELAX THROUGH MONDAY AS HIGH PRESSURE
BECOMES DOMINATE WX FEATURE. FOR SIGNIFICANT SEAS...AN ESE GROUND
SWELL AT 9 SECOND PERIODS TO APPROACH THE LOCAL WATERS
SUNDAY...AND AFFECT THE WATERS LATE SUNDAY NIGHT THROUGH MONDAY.
EXPECT WIND DRIVEN WAVES AT 4 TO 6 SECOND PERIODS WILL DOMINATE AT
THE START...BUT EVEN OUT ONCE THE SWELL TRAVERSES THE WATERS. 2 TO
3 FT...LIKELY HIGHER ONCE THE SWELL PUSHES ACROSS THE WATERS. LATEST
WAVEWATCH3 ILLUSTRATES THIS OCCURRENCE.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 330 AM SATURDAY...THIS PERIOD WILL BE HIGHLIGHTED BY
SUPPRESSED UPPER RIDGING TO THE SOUTH WITH WEAK HIGH PRESSURE
SPORADICALLY COVERING THE SE STATES. OVERALL WINDS WILL BE
LIGHT...LESS THAN 10 KT. PREVAILING WIND DIRECTION WILL BE
SOMEWHAT DIFFICULT TO FORECAST...COULD ALMOST GO WITH A VARIABLE
DIRECTION AT TIMES. SIGNIFICANT SEAS WILL DROP TO AROUND 2 FT BY
WED AS THE DECAYING ESE SWELL GIVES WAY TO LOCALLY PRODUCED WIND
DRIVEN WAVES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...RJD
SHORT TERM...DCH
LONG TERM...DCH
AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
716 AM EDT SAT AUG 17 2013
.SYNOPSIS...
A WARM FRONT EXTENDING FROM EASTERN GEORGIA TO JUST OFF THE
CAROLINA COAST WILL LIFT NORTH AND THROUGH THE EASTERN CAROLINAS
TODAY...AND BE ACCOMPANIED BY HEAVY RAIN AND THUNDERSTORMS. THE
FRONT OR TROF OF LOW PRESSURE WILL STALL OVER THE CAROLINAS...THEN
GRADUALLY DISSIPATE BY WEDNESDAY AS BERMUDA HIGH PRESSURE OFFSHORE
BECOMES THE MAIN INFLUENCE ON OUR WEATHER. BELOW-NORMAL
TEMPERATURES THIS WEEKEND SHOULD RETURN TO NORMAL BY TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 6:30 AM SATURDAY...NO CHANGES TO THE FORECAST WITH THE
LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS:
UNSEASONABLY COOL TEMPERATURES WITH CLOUDY SKIES AND THE CERTAINTY
OF PRECIPITATION WILL BE THE RULE FOR TODAY AS A QUASI-STATIONARY
FRONT WAVERS OVER THE COASTAL PLAIN.
AT THE SURFACE THIS MORNING THE QUASI-STATIONARY FRONT EXTENDS ALONG
THE COAST FROM THE OUTER BANKS TO NEAR SAVANNAH...THEN INLAND ACROSS
SOUTHERN GEORGIA. A SERIES OF WAVES MOVING ALONG THE FRONT ARE
INDUCED BY UPPER DISTURBANCES RIDING UP THE LEADING EDGE OF AN
UNSEASONABLY DEEP H/5 TROUGH NOW DOMINATING EASTERN CONUS.
OVERRUNNING PATTERN IN PLACE PAST FEW DAYS STILL VERY EVIDENT...WITH
A DEEP TROPICALLY-SOURCED AIRMASS OVERRIDING A RELATIVELY COOL AND
MOIST EASTERLY FLOW CLOSER TO THE SURFACE. A WEDGE OF HIGH PRESSURE
WILL CONTINUE TO EXTEND SW ALONG THE APPALACHIANS THROUGH THE
PERIOD. CONSENSUS OF GUIDANCE HAS A CLOSED LOW FORMING FROM AN OPEN
WAVE ALONG THE FRONT TODAY...ULTIMATELY LIFTING THE NORTHERN PORTION
OF THE FRONT NORTH AND EFFECTIVELY PUTTING THE COASTAL CAROLINAS IN
THE WARM SECTOR OF THE SYSTEM FOR A BRIEF TIME.
MODEL SOUNDINGS CONTINUE TO SHOW A VERY MOIST AIRMASS WITH P/W
VALUES IN THE 2.25 INCH RANGE. COMBINATION OF A SATURATED
COLUMN...FAVORABLE DYNAMICS AND THE FRONTAL BOUNDARY WILL MAKE FOR A
VERY RAINY DAY. GIVEN THIS SCENARIO...100 POPS ARE CERTAINLY
WARRANTED. HAVE MAINTAINED THE POSSIBILITY THAT THUNDERSTORMS COULD
PRODUCE HEAVY RAIN TODAY AND TONIGHT.
TEMPERATURES WILL CONTINUE TO RUN WELL BELOW NORMAL...WITH HIGHS
RANGING FROM THE LOWER AND MID 70S INLAND TO THE UPPER 70S AT THE
COAST...AND LOWS RANGING FROM THE MID 60S TO AROUND 70.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 315 AM...FOR SUNDAY THE FA WILL LIE IN BETWEEN THE WESTERN
ATLANTIC RIDGE AND THE CUTOFF LOW ACROSS THE CENTRAL MISSISSIPPI
VALLEY. AMPLE SUPPLY OF MOISTURE ACROSS THE FA...AS FEEDS FROM
BOTH THE ATLANTIC AT THE LOW LEVELS...AND THE GULF OF MEXICO MID
AND UPPER LEVELS...ADVECT ACROSS THE FA. WEAK AREA OF LOW
PRESSURE IS PROGGED BY THE MODELS TO TRAVEL ALONG A COASTAL
TROF/FRONT ORIENTED NE-SW OVER THE ATLANTIC WATERS..AND PARALLEL
TO THE CAROLINA COASTS. THE LOW DEPARTS TO THE NE OFF THE DELMARVA
COAST BY DAYBREAK MONDAY. UPSTAIRS...THE CUTOFF LOW ACROSS THE
CENTRAL PART OF THE U.S. OPENS UP INTO A PROGRESSIVE POSITIVELY
TILTED S/W TROF WHICH REACHES THE NE AND MID-ATLANTIC STATES LATE
MONDAY NIGHT. AT THE SFC ON SUNDAY...WEAK HIGH PRESSURE IS PROGGED
TO AFFECT THE FA. ONE WOULD THINK THAT WE ARE SAFE FROM ANY PCPN
OCCURRENCE ON MONDAY. HOWEVER...MOISTURE REMAINS IN ABUNDANCE
ACROSS THE FA. WEAK 5H VORTICIES ARE PROGGED TO PUSH ACROSS THE FA
MONDAY INTO MONDAY NIGHT. IN ADDITION...ANY AMOUNT OF INSOLATION
EITHER DAY WILL RESULT IN FURTHER DESTABILIZATION OF THE ATM
LOCALLY. AS A RESULT OF ALL THIS SAID...POPS SUNDAY AND MONDAY
WILL BE IN THE MODERATE TO HIGH CHANCE CATEGORY. THIS IS IN GOOD
AGREEMENT WITH BOTH THE NAM AND GFS MOS GUIDANCE. FOR MAX
TEMPS...LEANED TOWARD THE SLIGHTLY HIGHER NAM MOS GUIDANCE WHEN
COMPARED TO THE GFS. AS FOR LOWS...BOTH MODEL MOS GUIDANCE QUITE
SIMILAR AND SEE NO REASON TO DETOUR FROM THEIR OUTPUT. THE LATEST
HPC 48 HR GUIDANCE FOR RAINFALL ACROSS THE ILM CWA...INDICATES
BETWEEN 1 TO 2 INCHES POSSIBLE. AT THIS POINT A FLOOD WATCH IS NOT
RECOMMENDED...BUT AS GROUNDS FURTHER BECOME SATURATED...WILL HAVE
TO RE-VISIT THIS ISSUE ONCE AGAIN IF HPC FUTURE PCPN FORECASTS
COME IN AT MODEST TO HIGH LEVELS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 315 AM SATURDAY...FOR TUESDAY...THE OPENED UP UPPER TROF
WILL JUST BECOME A MEMORY AS ITS IS ABSORBED WITHIN THE MAIN BELT
OF THE UPPER WESTERLIES. WITH NW FLOW ALOFT...THIN BAND OF
MOISTURE...HAVING BEEN STRETCHED APART WILL DROP SE-
WARD...AND CROSS THE FA DURING WEDNESDAY. BEWARE THE NW FLOW...AN
ADAGE THAT HAS COME TO LIGHT WHEN DEALING WITH CONVECTION DROPPING
SE-WARD FROM UPSTREAM. A MCC OR MCS USUALLY IS THE CULPRIT WITH
THIS TYPE MID/UPPER LEVEL FLOW. CHANCE POPS WILL CONTINUE FOR TUE
AND WED. BY THU AND FRI...MODELS DIVERGE FROM ONE ANOTHER WITH
THEIR OWN RESPECTIVE SOLUTIONS DEALING WITH THE RE-TURN OF
MOISTURE AND INCREASING POPS. REMAINED RATHER SOMEWHAT LOW-KEY
WITH POPS THIS LATE IN THE TIME PERIOD DUE TO THE UNCERTAINTY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 12Z...CEILINGS THIS MORNING WILL BE PREDOMINATELY
IFR...HOWEVER THEY WILL PROBABLY BOUNCE IN AND OUT OF
MVFR...PARTICULARLY AFTER 15Z. THE HRRR MODEL HAS A SURFACE LOW
OFFSHORE THAT WILL MOVE SLOWLY NORTHEAST THROUGH THE DAY. THE MODEL
IS NOT ALL THAT ENTHUSED WITH THE PRECIP TODAY...WITH MAINLY ONLY
SCATTERED ACTIVITY. BASED ON THE CURRENT RADAR...THIS SCENARIO SEEMS
REASONABLE. VISIBILITIES IN THE RAIN COULD LOWER TO IFR...BUT
PREDOMINATELY MVFR. WINDS ARE A BIT MORE NORTHERLY THAN PREVIOUSLY
THOUGHT...PARTICULARLY INLAND ON THE BACK SIDE OF THE SURFACE LOW.
LOOK FOR THE WINDS TO SHIFT MORE NORTHWESTERLY AS THE LOW EXITS THE
REGION THIS AFTERNOON.
EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 6:30 AM SATURDAY...NO CHANGES TO THE FORECAST WITH THE
LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS:
THE PRESENCE OF A QUASI-STATIONARY FRONT OVER THE COASTAL PLAN OF
THE EASTERN CAROLINAS WILL KEEP WINDS GENERALLY LIGHT THROUGH THE
PERIOD. WINDS WILL BE IN THE 10 KT RANGE...WITH SEAS OF 2 TO 3 FT.
BIGGEST THREAT OVER THE COASTAL WATERS TODAY WILL BE FROM HEAVY
RAIN AND ISOLATED THUNDERSTORMS...ESPECIALLY DURING THE DAYLIGHT
HOURS.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE WESTERN ATLANTIC UPPER RIDGE AXIS IS
PROGGED TO EXTEND FURTHER WESTWARD...PUSHING THE MAIN MOISTURE
PLUME ORIENTED NE-SW FURTHER INLAND. THIS WILL POSSIBLY
PROVIDE SOME DRYING CONDITIONS FOR MARINERS TRAVERSING THE LOCAL
AND OFFSHORE WATERS LATER SUNDAY INTO MONDAY. AN EXITING SFC LOW
TO THE NE ALONG A COASTAL FRONT WILL HIGHLIGHT SUNDAY...FOLLOWED
BY WEAK HIGH PRESSURE ACROSS THE AREA FOR MONDAY. THE SFC PRESSURE
GRADIENT WILL TIGHTEST AT THE BEGINNING OF THE SHORT TERM
RELATIVELY SPEAKING...THEN RELAX THROUGH MONDAY AS HIGH PRESSURE
BECOMES DOMINATE WX FEATURE. FOR SIGNIFICANT SEAS...AN ESE GROUND
SWELL AT 9 SECOND PERIODS TO APPROACH THE LOCAL WATERS
SUNDAY...AND AFFECT THE WATERS LATE SUNDAY NIGHT THROUGH MONDAY.
EXPECT WIND DRIVEN WAVES AT 4 TO 6 SECOND PERIODS WILL DOMINATE AT
THE START...BUT EVEN OUT ONCE THE SWELL TRAVERSES THE WATERS. 2 TO
3 FT...LIKELY HIGHER ONCE THE SWELL PUSHES ACROSS THE WATERS. LATEST
WAVEWATCH3 ILLUSTRATES THIS OCCURRENCE.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 330 AM SATURDAY...THIS PERIOD WILL BE HIGHLIGHTED BY
SUPPRESSED UPPER RIDGING TO THE SOUTH WITH WEAK HIGH PRESSURE
SPORADICALLY COVERING THE SE STATES. OVERALL WINDS WILL BE
LIGHT...LESS THAN 10 KT. PREVAILING WIND DIRECTION WILL BE
SOMEWHAT DIFFICULT TO FORECAST...COULD ALMOST GO WITH A VARIABLE
DIRECTION AT TIMES. SIGNIFICANT SEAS WILL DROP TO AROUND 2 FT BY
WED AS THE DECAYING ESE SWELL GIVES WAY TO LOCALLY PRODUCED WIND
DRIVEN WAVES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DCH
NEAR TERM...REK
SHORT TERM...DCH
LONG TERM...DCH
AVIATION...43
MARINE...DCH/REK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
349 PM CDT SAT AUG 17 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 343 PM CDT SAT AUG 17 2013
THE MAIN FORECAST CHALLENGE FOR THE PERIOD WILL BE THE PRECIP CHANCES
LATER THIS EVENING AND AGAIN ON SUNDAY.
A WEAK SURFACE BOUNDARY IS BEGINNING TO ENTER WESTERN NORTH DAKOTA
THIS AFTERNOON. A STRONG CAP IN PLACE SHOULD INHIBIT AFTERNOON
CONVECTION ALONG THE BOUNDARY. HOWEVER...AS THIS BOUNDARY PUSHES
INTO CENTRAL NORTH DAKOTA THIS EVENING...THUNDERSTORMS COULD DEVELOP
OVER NORTH CENTRAL NORTH DAKOTA PROXIMATE TO THE BEST UPPER LEVEL
DYNAMICS AND WEAKEST CAP. THE 12Z ECMWF/NAM AND 17Z HRRR PROG THIS
SCENARIO SO DECIDED TO KEEP SLIGHT CHANCE POPS IN THE GRIDS NORTH
CENTRAL TONIGHT. SOME STORMS COULD BECOME STRONG SO WILL HIGHLIGHT
THIS THREAT IN THE HWO FOR NOW.
AS THE BOUNDARY MOVES INTO EASTERN NORTH DAKOTA SUNDAY...IT IS
PROGGED TO BECOME STALLED ACROSS CENTRAL NORTH DAKOTA. AN UPPER WAVE
IS FORECAST TO MOVE OVER NORTH DAKOTA THROUGH THE DAY SUNDAY. AS IT
DOES...THE CHANCES FOR THUNDERSTORMS WILL GRADUALLY OVERSPREAD THE
STATE FROM WEST TO EAST. STORMS SHOULD REMAIN BELOW SEVERE CRITERIA
THROUGH SUNDAY AFTERNOON...BUT COULD STRENGTHEN TO SEVERE SUNDAY
EVENING. SEE LONG TERM DISCUSSION BELOW FOR MORE DETAILS.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 343 PM CDT SAT AUG 17 2013
THE MAIN FORECAST HIGHLIGHT FOR THE EXTENDED PERIOD WILL BE THE
POTENTIAL FOR SEVERE THUNDERSTORMS SUNDAY EVENING.
THEREAFTER...PROGRESSIVE WEST TO SOUTHWEST FLOW WITH MULTIPLE
EMBEDDED UPPER LEVEL IMPULSES IS FORECAST THROUGH THE REMAINDER OF
THE PERIOD. 12Z MODEL DETERMINISTIC MODEL GUIDANCE IS IN GOOD
AGREEMENT THROUGH MID BEFORE SOLUTIONS DIVERGE LATE WEEK.
THE POTENTIAL FOR SEVERE THUNDERSTORMS WILL INCREASE SUNDAY
EVENING AS THE COMBINED FORCING FROM THE SURFACE FRONTAL BOUNDARY
AND UPPER LEVEL WAVE ERODES THE CAP. THIS FORCING SHOULD BE
SUFFICIENT ENOUGH TO BREAK THE CAP BY EARLY SUNDAY EVENING AND ALLOW
CONVECTION TO FIRE ALONG THE SURFACE FRONTAL BOUNDARY. THE
ANTECEDENT ENVIRONMENT WILL BE FAVORABLE FOR THE DEVELOPMENT OF
SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL AND MOST OF EASTERN
NORTH DAKOTA...WITH ML CAPE FORECAST TO BE NEAR 2000 J/KG BY LATE
SUNDAY AFTERNOON/EVENING...INCREASING BOUNDARY LAYER MOISTURE
(DEWPOINTS INCREASING INTO THE 60S)...AND 0-6 KM BULK SHEAR TO BE
IN THE 25 TO 35 M/S RANGE. FURTHERMORE...THE LATEST DAY 2 OUTLOOK
FROM SPC HAS PARTS OF CENTRAL AND MOST OF EASTERN NORTH DAKOTA IN
THE SLIGHT RISK. HAIL AND DAMAGING WINDS LOOK TO BE THE MAIN
THREATS AND AT THIS TIME WILL HIGHLIGHT THE POSSIBILITY OF SEVERE
THUNDERSTORMS IN THE HWO AND STATE FORECAST.
FOLLOWING THE FRONTAL PASSAGE/SHORTWAVE MONDAY...DAYTIME UPPER
LEVEL RIDGING WILL GIVE WAY TO WESTERLY FLOW ALOFT. THIS WILL
CONTINUE THROUGH TUESDAY EVENING AHEAD OF THE EXPECTED COLD FRONT
WEDNESDAY AND THURSDAY. CANNOT RULE OUT THE POSSIBILITY OF
THUNDERSTORMS/SHOWERS ACROSS THE AREA...AS SEVERAL WEAK IMPULSES
MOVE OVER THE STATE. PRECIPITATION CHANCES WILL THEN INCREASE AS
A COLD FRONT AND AN UPPER LEVEL SHORT WAVE APPROACH NORTHERN
NORTH DAKOTA LATE TUESDAY NIGHT/EARLY WEDNESDAY MORNING...AND AS THEY
MOVE OVER THE AREA WEDNESDAY. SIMILAR TO PREVIOUS RUNS...THE 12Z
ECWMF CONTINUES TO PAINT A DECENT AREA OF SHOWERS/THUNDERSTORMS
OVER THE WEST AND CENTRAL. HOWEVER...THE 12Z GFS CONTINUES TO KEEP
NORTH DAKOTA DRY AS IT FORECASTS UPPER LEVEL RIDGING TAKING PLACE.
WILL KEEP THE ALLBLEND SOLUTION...TO SPLIT THE DIFFERENCE BETWEEN
THE ECWMF AND GFS. FOR FRIDAY AND SATURDAY...PRECIPITATION CHANCES
WILL CONTINUE AS SOUTHWESTERLY FLOW TAKES HOLD.
MEANWHILE...H850 TEMPERATURES WILL INCREASE TO BETWEEN +26 AND +30 C
ON TUESDAY. THIS WILL TRANSLATE TO SURFACE TEMPERATURES IN THE
90S...WITH NEAR 100 DEGREE READING FOR FAR SOUTHERN NORTH DAKOTA.
COOLER TEMPERATURES ARE FORECAST ONCE THE COLD FRONT PASSES
THROUGH THE AREA WEDNESDAY...WHERE TEMPERATURES ARE EXPECTED TO BE
MAINLY IN THE 80S DURING THE DAY AND UPPER 50S/LOWER 60S AT NIGHT
THROUGH SATURDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 103 PM CDT SAT AUG 17 2013
VFR CONDITIONS WILL PREVAIL ACROSS NORTH DAKOTA THROUGH THE TAF
PERIOD. THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS NEAR KMOT THIS
EVENING. CONFIDENCE IS LOW REGARDING AVIATION IMPACTS.
THEREFORE...ONLY INCLUDED VCTS IN THE KMOT TAF BETWEEN 00Z-05Z.
FURTHERMORE...IFR CIGS/VSBYS COULD DEVELOP NEAR KJMS BETWEEN 11Z-
13Z. CONFIDENCE IS LOW IN THIS MATERIALIZING AND WILL THEREFORE
LEAVE OUT OF THE KJMS TAF FOR NOW.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...TM
LONG TERM...LTH
AVIATION...AC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
103 PM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 103 PM CDT SAT AUG 17 2013
STRATUS DECK OVER THE JAMES RIVER BASIN IS BEGINNING TO ERODE AWAY
WITH THE ONSET OF DAYTIME HEATING. THE LOW CLOUDS SHOULD DISSIPATE BY
2 PM CDT.
OTHERWISE...ONLY MODIFIED THE HOURLY SENSIBLE WEATHER GRIDS BASED
ON CURRENT OBS/TRENDS. THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 1041 AM CDT SAT AUG 17 2013
LOW CLOUDS AND PATCHY FOG ARE LINGERING OVER SOUTH CENTRAL AND
SOUTHEASTERN NORTH DAKOTA LONGER THAN ANTICIPATED. AS A
RESULT...UPDATED THE FORECAST TO CONTINUE THE CLOUDY AND PATCHY
FOG CONDITIONS PRIMARILY ACROSS THE JAMES RIVER BASIN THROUGH THE
MID-DAY HOURS. THIS SHOULD ALSO HAMPER MORNING TEMPERATURE WARMING
TRENDS. HOWEVER...ONCE THE LOW CLOUDS AND FOG BURN
OFF...TEMPERATURES SHOULD RAPIDLY INCREASE THIS AFTERNOON.
UPDATE ISSUED AT 830 AM CDT SAT AUG 17 2013
SENT OUT A QUICK UPDATE TO INCREASE FOG COVERAGE OVER THE JAMES
RIVER BASIN THROUGH THE MID-MORNING HOURS. EVEN THOUGH SURFACE
WINDS ARE AROUND 10 KNOTS...AREAS OF FOG...DENSE AT
TIMES...CONTINUE TO DEVELOP OVER PORTIONS OF SOUTHCENTRAL AND
SOUTHEASTERN NORTH DAKOTA.
THE FOG SHOULD BEGIN TO DISSIPATE BY THE MID TO LATE MORNING HOURS
AS VERTICAL MIXING COMMENCES.
UPDATE ISSUED AT 636 AM CDT SAT AUG 17 2013
THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS
THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE
SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN
AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR
CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z
FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED
SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST.
REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT AUG 17 2013
THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS
MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS
AFTERNOON AND TONIGHT.
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG
EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS
THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND
INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN
LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO
COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE
THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST.
THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL
BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700
TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS
AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING
LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE
BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE
LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN
NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT
LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND
NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER
FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS
THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE
TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES
SHOULD MINIMIZE THE HAIL THREAT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT AUG 17 2013
POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE
MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE
WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A
LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING
DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE
GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN
LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW.
FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED
COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA.
ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A
CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE
FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND
00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH
STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN
2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER
VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE
ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG
THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL
NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON
BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST
WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND
CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES
ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A
CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK
EVOLVE IN FUTURE FORECASTS.
FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD
RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT.
EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM
OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND
THE APPROACH OF A WEAK SHORTWAVE.
FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM
CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT
WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA
TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY
WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS
HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH.
THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR
WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN
EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA
FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL
NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE
IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING
THE ECMWF.
BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST
TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO
WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN
THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN
THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 103 PM CDT SAT AUG 17 2013
VFR CONDITIONS WILL PREVAIL ACROSS NORTH DAKOTA THROUGH THE TAF
PERIOD. THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS NEAR KMOT THIS
EVENING. CONFIDENCE IS LOW REGARDING AVIATION IMPACTS.
THEREFORE...ONLY INCLUDED VCTS IN THE KMOT TAF BETWEEN 00Z-05Z.
FURTHERMORE...IFR CIGS/VSBYS COULD DEVELOP NEAR KJMS BETWEEN 11Z-
13Z. CONFIDENCE IS LOW IN THIS MATERIALIZING AND WILL THEREFORE
LEAVE OUT OF THE KJMS TAF FOR NOW.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...CK
LONG TERM...KS
AVIATION...AC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1041 AM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 1041 AM CDT SAT AUG 17 2013
LOW CLOUDS AND PATCHY FOG ARE LINGERING OVER SOUTH CENTRAL AND
SOUTHEASTERN NORTH DAKOTA LONGER THAN ANTICIPATED. AS A
RESULT...UPDATED THE FORECAST TO CONTINUE THE CLOUDY AND PATCHY
FOG CONDITIONS PRIMARILY ACROSS THE JAMES RIVER BASIN THROUGH THE
MID-DAY HOURS. THIS SHOULD ALSO HAMPER MORNING TEMPERATURE WARMING
TRENDS. HOWEVER...ONCE THE LOW CLOUDS AND FOG BURN
OFF...TEMPERATURES SHOULD RAPIDLY INCREASE THIS AFTERNOON.
UPDATE ISSUED AT 830 AM CDT SAT AUG 17 2013
SENT OUT A QUICK UPDATE TO INCREASE FOG COVERAGE OVER THE JAMES
RIVER BASIN THROUGH THE MID-MORNING HOURS. EVEN THOUGH SURFACE
WINDS ARE AROUND 10 KNOTS...AREAS OF FOG...DENSE AT
TIMES...CONTINUE TO DEVELOP OVER PORTIONS OF SOUTHCENTRAL AND
SOUTHEASTERN NORTH DAKOTA.
THE FOG SHOULD BEGIN TO DISSIPATE BY THE MID TO LATE MORNING HOURS
AS VERTICAL MIXING COMMENCES.
UPDATE ISSUED AT 636 AM CDT SAT AUG 17 2013
THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS
THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE
SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN
AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR
CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z
FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED
SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST.
REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT AUG 17 2013
THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS
MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS
AFTERNOON AND TONIGHT.
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG
EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS
THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND
INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN
LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO
COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE
THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST.
THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL
BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700
TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS
AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING
LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE
BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE
LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN
NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT
LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND
NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER
FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS
THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE
TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES
SHOULD MINIMIZE THE HAIL THREAT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT AUG 17 2013
POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE
MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE
WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A
LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING
DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE
GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN
LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW.
FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED
COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA.
ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A
CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE
FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND
00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH
STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN
2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER
VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE
ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG
THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL
NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON
BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST
WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND
CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES
ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A
CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK
EVOLVE IN FUTURE FORECASTS.
FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD
RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT.
EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM
OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND
THE APPROACH OF A WEAK SHORTWAVE.
FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM
CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT
WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA
TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY
WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS
HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH.
THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR
WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN
EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA
FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL
NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE
IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING
THE ECMWF.
BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST
TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO
WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN
THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN
THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 636 AM CDT SAT AUG 17 2013
IFR/LIFR CONDITIONS IN LOW CLOUDS OVER KBIS-KJMS WILL GRADUALLY
IMPROVE TO VFR BY MIDDAY. ONCE THE FOG AND STRATUS EXIT...WILL
CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME CONCERN AN
ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK TONIGHT...BUT AM
NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE FORECAST. WINDS WILL BE
FROM A SOUTHERLY DIRECTION THIS MORNING...BUT WESTERN LOCATIONS
WILL TURN NORTHERLY AS A FRONTAL BOUNDARY CROSSES THE AREA.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...CK
LONG TERM...KS
AVIATION...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
830 AM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 830 AM CDT SAT AUG 17 2013
SENT OUT A QUICK UPDATE TO INCREASE FOG COVERAGE OVER THE JAMES
RIVER BASIN THROUGH THE MID-MORNING HOURS. EVEN THOUGH SURFACE
WINDS ARE AROUND 10 KNOTS...AREAS OF FOG...DENSE AT
TIMES...CONTINUE TO DEVELOP OVER PORTIONS OF SOUTHCENTRAL AND
SOUTHEASTERN NORTH DAKOTA.
THE FOG SHOULD BEGIN TO DISSIPATE BY THE MID TO LATE MORNING HOURS
AS VERTICAL MIXING COMMENCES.
UPDATE ISSUED AT 636 AM CDT SAT AUG 17 2013
THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS
THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE
SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN
AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR
CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z
FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED
SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST.
REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT AUG 17 2013
THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS
MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS
AFTERNOON AND TONIGHT.
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG
EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS
THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND
INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN
LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO
COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE
THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST.
THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL
BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700
TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS
AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING
LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE
BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE
LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN
NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT
LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND
NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER
FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS
THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE
TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES
SHOULD MINIMIZE THE HAIL THREAT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT AUG 17 2013
POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE
MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE
WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A
LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING
DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE
GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN
LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW.
FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED
COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA.
ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A
CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE
FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND
00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH
STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN
2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER
VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE
ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG
THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL
NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON
BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST
WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND
CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES
ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A
CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK
EVOLVE IN FUTURE FORECASTS.
FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD
RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT.
EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM
OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND
THE APPROACH OF A WEAK SHORTWAVE.
FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM
CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT
WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA
TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY
WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS
HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH.
THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR
WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN
EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA
FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL
NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE
IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING
THE ECMWF.
BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST
TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO
WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN
THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN
THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 636 AM CDT SAT AUG 17 2013
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS AND FOG
APPROACHING KJMS. EXPECT A CEILING AT KJMS TO ARRIVE SOON AND BE
BELOW 1KFT. WILL NOT GO TOO LOW WITH VISIBILITIES SINCE MOST SPOTS
ACROSS SOUTH DAKOTA IN THE STRATUS HAVE BEEN IN THE 3-5SM RANGE.
WILL ALSO SHOW A VISIBILITY REDUCTION AT KBIS THIS MORNING WITH
SCATTERED CLOUDS AROUND 500 FT. ONCE THE FOG AND STRATUS
EXIT...WILL CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME
CONCERN AN ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK
TONIGHT...BUT AM NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE
FORECAST. WINDS WILL BE FROM A SOUTHERLY DIRECTION THIS
MORNING...BUT WESTERN LOCATIONS WILL TURN NORTHERLY AS A FRONTAL
BOUNDARY CROSSES THE AREA.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION...CORRECTED
NWS BISMARCK ND
645 AM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 636 AM CDT SAT AUG 17 2013
THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS
THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE
SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN
AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR
CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z
FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED
SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST.
REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT AUG 17 2013
THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS
MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS
AFTERNOON AND TONIGHT.
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG
EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS
THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND
INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN
LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO
COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE
THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST.
THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL
BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700
TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS
AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING
LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE
BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE
LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN
NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT
LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND
NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER
FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS
THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE
TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES
SHOULD MINIMIZE THE HAIL THREAT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT AUG 17 2013
POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE
MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE
WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A
LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING
DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE
GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN
LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW.
FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED
COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA.
ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A
CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE
FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND
00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH
STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN
2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER
VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE
ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG
THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL
NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON
BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST
WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND
CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES
ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A
CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK
EVOLVE IN FUTURE FORECASTS.
FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD
RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT.
EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM
OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND
THE APPROACH OF A WEAK SHORTWAVE.
FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM
CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT
WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA
TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY
WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS
HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH.
THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR
WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN
EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA
FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL
NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE
IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING
THE ECMWF.
BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST
TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO
WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN
THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN
THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 636 AM CDT SAT AUG 17 2013
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS AND FOG
APPROACHING KJMS. EXPECT A CEILING AT KJMS TO ARRIVE SOON AND BE
BELOW 1KFT. WILL NOT GO TOO LOW WITH VISIBILITIES SINCE MOST SPOTS
ACROSS SOUTH DAKOTA IN THE STRATUS HAVE BEEN IN THE 3-5SM RANGE.
WILL ALSO SHOW A VISIBILITY REDUCTION AT KBIS THIS MORNING WITH
SCATTERED CLOUDS AROUND 500 FT. ONCE THE FOG AND STRATUS
EXIT...WILL CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME
CONCERN AN ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK
TONIGHT...BUT AM NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE
FORECAST. WINDS WILL BE FROM A SOUTHERLY DIRECTION THIS
MORNING...BUT WESTERN LOCATIONS WILL TURN NORTHERLY AS A FRONTAL
BOUNDARY CROSSES THE AREA.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
636 AM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 636 AM CDT SAT AUG 17 2013
THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS
THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE
SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN
AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR
CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 13Z
THEN BEGINNING TO DISSIPATED THROUGH 18Z. THUS HAVE ADJUSTED SKY
GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST. REST
OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT AUG 17 2013
THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS
MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS
AFTERNOON AND TONIGHT.
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG
EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS
THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND
INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN
LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO
COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE
THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST.
THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL
BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700
TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS
AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING
LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE
BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE
LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN
NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT
LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND
NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER
FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS
THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE
TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES
SHOULD MINIMIZE THE HAIL THREAT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT AUG 17 2013
POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE
MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE
WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A
LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING
DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE
GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN
LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW.
FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED
COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA.
ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A
CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE
FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND
00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH
STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN
2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER
VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE
ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG
THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL
NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON
BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST
WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND
CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES
ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A
CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK
EVOLVE IN FUTURE FORECASTS.
FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD
RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT.
EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM
OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND
THE APPROACH OF A WEAK SHORTWAVE.
FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM
CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT
WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA
TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY
WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS
HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH.
THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR
WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN
EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA
FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL
NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE
IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING
THE ECMWF.
BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST
TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO
WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN
THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN
THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 636 AM CDT SAT AUG 17 2013
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS AND FOG
APPROACHING KJMS. EXPECT A CEILING AT KJMS TO ARRIVE SOON AND BE
BELOW 1KFT. WILL NOT GO TOO LOW WITH VISIBILITIES SINCE MOST SPOTS
ACROSS SOUTH DAKOTA IN THE STRATUS HAVE BEEN IN THE 3-5SM RANGE.
WILL ALSO SHOW A VISIBILITY REDUCTION AT KBIS THIS MORNING WITH
SCATTERED CLOUDS AROUND 500 FT. ONCE THE FOG AND STRATUS
EXIT...WILL CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME
CONCERN AN ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK
TONIGHT...BUT AM NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE
FORECAST. WINDS WILL BE FROM A SOUTHERLY DIRECTION THIS
MORNING...BUT WESTERN LOCATIONS WILL TURN NORTHERLY AS A FRONTAL
BOUNDARY CROSSES THE AREA.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
324 AM CDT SAT AUG 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT AUG 17 2013
THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS
MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS
AFTERNOON AND TONIGHT.
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG
EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS
THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND
INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN
LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO
COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE
THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST.
THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL
BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700
TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS
AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING
LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE
BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE
LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN
NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT
LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND
NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER
FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS
THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE
TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES
SHOULD MINIMIZE THE HAIL THREAT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT AUG 17 2013
POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE
MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE
WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A
LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING
DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE
GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN
LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW.
FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED
COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA.
ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A
CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE
FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND
00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH
STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN
2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER
VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE
ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG
THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL
NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON
BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST
WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND
CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES
ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A
CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK
EVOLVE IN FUTURE FORECASTS.
FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD
RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT.
EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM
OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND
THE APPROACH OF A WEAK SHORTWAVE.
FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM
CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT
WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA
TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY
WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS
HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH.
THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR
WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN
EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA
FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL
NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE
IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING
THE ECMWF.
BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST
TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO
WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN
THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN
THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 324 AM CDT SAT AUG 17 2013
THE POTENTIAL FOR FOG AND LOW CLOUDS AT KJMS AND KBIS ARE THE
PRIMARY CONCERNS FOR THE 06Z FORECAST. AREAS JUST EAST OF KJMS
HAVE BECOME NEARLY SATURATED AT THE SURFACE WITH LOW TEMPERATURE /
DEWPOINT SPREADS EARLY THIS MORNING. THE LATEST HRRR AND NAM
NUMERICAL GUIDANCE SUGGESTS THERE COULD BE FOG DEVELOPMENT AT
KJMS...AND WILL SHOW THAT IN THE LATEST TAF. LESSER CHANCES FOR
VISIBILITY REDUCTIONS ARE SHOWN AT KBIS...AND WILL CARRY VCFG TO
SUGGEST FOG COULD BE IN THE AREA EARLY THIS MORNING. THE REMAINDER
OF THE FORECASTS WILL BE VFR. WINDS WILL BE FROM A SOUTHERLY
DIRECTION TO START...BUT WESTERN AERODROMES WILL SEE A SHIFT TO
THE NORTHWEST LATER IN THE PERIOD AS A FRONTAL BOUNDARY MOVES INTO
THE REGION.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1225 AM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 1225 AM CDT SAT AUG 17 2013
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS PATCHY STRATUS
IN EASTERN SOUTH DAKOTA HAS DIMINISHED OVER THE PAST FEW HOURS.
THE LATEST HOURLY TEMPERATURE / DEWPOINT PLOT SHOWS AREAS JUST EAST
OF THE FORECAST AREA HAVE BECOME NEARLY SATURATED...AND WOULD
EXPECT ADJACENT AREAS IN THE JAMES RIVER VALLEY TO SHOW A SIMILAR
TREND EARLY THIS MORNING. THE GOING FORECAST ALREADY HAS PATCHY
FOG IN THAT AREA...AND AFTER LOOKING AT THE HRRR DECIDED TO EXPAND
THE FOG A LITTLE FARTHER WEST. WILL ADJUST THE TEMPERATURE /
DEWPOINT SPREADS ACCORDINGLY...OTHERWISE MADE ONLY MINOR
ADJUSTMENTS TO THE GRIDS.
UPDATE ISSUED AT 924 PM CDT FRI AUG 16 2013
MINOR CHANGES IN HOURLY TEMPERATURES TO REFLECT CURRENT TRENDS.
OTHERWISE ONGOING FORECAST FOR TONIGHT IS ON TRACK. CLEAR SKIES
AND SOUTH WINDS EXPECTED FOR THE REST OF TONIGHT...EXCEPT THE
POSSIBILITY OF SOME FOG AND PERHAPS LOW CLOUDS MOVING INTO THE
JAMES RIVER VALLEY LATE TONIGHT. LATER SHIFTS WILL MONITOR ANY FOG
OR LOW CLOUDS FORMING AND MOVING NORTHWARD FROM EASTERN SOUTH
DAKOTA AND NEBRASKA.
UPDATE ISSUED AT 629 PM CDT FRI AUG 16 2013
SURFACE HIGH PRESSURE OVER IOWA AND LOW PRESSURE IN THE LEE OF THE
ROCKIES WAS KEEPING A SOUTHERLY WIND FLOW ACROSS THE DAKOTAS. DRY
AIR ALOFT WITH THE UPPER LEVEL RIDGE BUILDING WILL KEEP SKIES MOSTLY
CLEAR THIS EVENING. CURRENT FORECAST ON TRACK WITH NO CHANGES.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 337 PM CDT FRI AUG 16 2013
MID/UPPER LEVEL RIDGING OVER THE WESTERN GREAT PLAINS WILL
CONTINUE TO GENERATE A DRY AND TRANQUIL WEATHER PATTERN OVER
WESTERN AND CENTRAL NORTH DAKOTA THROUGH THE PERIOD.
WEAK GRADIENT FLOW COMBINED WITH ABUNDANT LOW-LEVEL MOISTURE
SHOULD ALLOW FOR PATCHY FOG DEVELOPMENT ACROSS THE JAMES RIVER
BASIN AFTER MIDNIGHT TONIGHT. IT SHOULD BE QUICK TO BURN OFF AFTER
SUNRISE SATURDAY MORNING.
ABOVE NORMAL TEMPERATURES ARE EXPECTED SATURDAY AS WAA DEVELOPS
AHEAD OF A SURFACE TROUGH. THE SURFACE TROUGH AXIS/BOUNDARY IS
PROGGED TO ENTER NORTHWESTERN NORTH DAKOTA BY SATURDAY AFTERNOON.
EVEN THOUGH THERE IS ENOUGH INSTABILITY AND DEEP LAYER SHEAR FOR
CONVECTIVE DEVELOPMENT...A DRY PUSH ALOFT SHOULD INHIBIT AFTERNOON
CONVECTION. THEREFORE...KEPT THE FORECAST DRY NORTHWEST FOR
SATURDAY AFTERNOON. HOWEVER...WOULD NOT BE SURPRISED IF A
THUNDERSTORM DEVELOPED ALONG THE BOUNDARY DURING THE LATE SATURDAY
AFTERNOON/EARLY EVENING HOURS. WILL CONTINUE TO MONITOR THE CAP
STRENGTH AS THE TIME GETS CLOSER.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 337 PM CDT FRI AUG 16 2013
WESTERLY ZONAL FLOW WILL ESTABLISH ITSELF EARLY IN THE PERIOD...AS
THE UPPER LEVEL RIDGE CONTINUES TO FLATTEN. SEVERAL EMBEDDED WEAK
IMPULSES...DEPICTED BY BOTH THE 12Z ECWMF AND GFS...WILL MOVE ACROSS
THE AREA SATURDAY NIGHT INTO SUNDAY. EVEN THOUGH THERE WILL BE AMPLE
CAPE...SUFFICIENT DEEP LAYER SHEAR AND MODEST BOUNDARY LAYER
MOISTURE...12Z NAM/GFS BUFR SOUNDINGS CONTINUE TO SUGGEST THAT A
WARM LAYER WILL BE PRESENT ALOFT...ENOUGH TO SUPPRESS CONVECTION
FROM FIRING ACROSS THE NORTHWEST BETWEEN 00Z AND 06Z SUNDAY. THE
WARM LAYER ALOFT/CAPPING INVERSION MAY BE OVERCOME ONCE THE
AFOREMENTIONED IMPULSES TRAVERSE THE AREA SUNDAY AND EARLY
MONDAY...ALLOWING CONVECTION TO FIRE ALONG AND AHEAD OF A WEAK COLD
FRONT FORECAST TO MOVE SOUTH. HAVE OPTED TO LEAVE SLIGHT CHANCE POPS
IN FOR NOW AND WILL CONTINUE TO MONITOR OVER THE NEXT FEW MODEL
RUNS.
MONDAY AND TUESDAY...WESTERLY ZONAL FLOW CONTINUES. EVEN WITH THE
WEAK COLD FRONTAL PASSAGE...H850 TEMPERATURES WILL REMAIN WARM
BETWEEN 20 TO 22 C...WARMING TO BETWEEN 24 AND 26 C TUESDAY WHILE
THE UPPER LEVEL RIDGE NUDGES NORTH. THIS WILL TRANSLATE TO SURFACE
TEMPERATURES IN THE 90S.
SIGNIFICANT DIFFERENCES DEVELOP BETWEEN THE 12Z GFS AND ECWMF
WEDNESDAY AND CONTINUES THROUGH THE REMAINDER OF THE PERIOD
REGARDING A STRONG COLD FRONTAL PASSAGE. THE 12Z ECWMF IS MORE
AGGRESSIVE PROPAGATING THIS FEATURE SOUTH WEDNESDAY...SUGGESTING
THAT SURFACE HIGH PRESSURE FROM CANADA WILL BUILD SOUTH IN ITS WAKE
AND COOLING H850 TEMPS BY OVER TEN DEGREES C. HOWEVER...THE 12Z GFS
DELAYS THE PASSAGE OF THE COLD FRONT UNTIL THURSDAY
MORNING/AFTERNOON. AS A CONSEQUENCE...THERE IS A 10C DIFFERENCE
BETWEEN THESE MODELS WEDNESDAY...AND THURSDAY ACROSS THE
SOUTH...WITH THE GFS CONTINUING 20 TO 22 C H850 TEMPS (MID TO UPPER
90S AND ISOLATED 100 DEGREE READINGS AT THE SURFACE)...WHILE THE
ECWMF SUGGESTS AN END TO THE HEAT...COOLING H850 TEMPS TO BETWEEN 14
TO 17 C (80S AT THE SURFACE WEDNESDAY AND COOLING TO THE 70S ON
THURSDAY). THUS HAVE STUCK WITH THE ALLBLEND SOLUTION GIVEN THE
SIGNIFICANT DISAGREEMENT BETWEEN THE GFS AND ECWMF.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1225 AM CDT SAT AUG 17 2013
THE POTENTIAL FOR FOG AND LOW CLOUDS AT KJMS AND KBIS ARE THE
PRIMARY CONCERNS FOR THE 06Z FORECAST. AREAS JUST EAST OF KJMS
HAVE BECOME NEARLY SATURATED AT THE SURFACE WITH LOW TEMPERATURE /
DEWPOINT SPREADS EARLY THIS MORNING. THE LATEST HRRR AND NAM
NUMERICAL GUIDANCE SUGGESTS THERE COULD BE FOG DEVELOPMENT AT
KJMS...AND WILL SHOW THAT IN THE LATEST TAF. LESSER CHANCES FOR
VISIBILITY REDUCTIONS ARE SHOWN AT KBIS...AND WILL CARRY VCFG TO
SUGGEST FOG COULD BE IN THE AREA EARLY THIS MORNING. THE REMAINDER
OF THE FORECASTS WILL BE VFR. WINDS WILL BE FROM A SOUTHERLY
DIRECTION TO START...BUT WESTERN AERODROMES WILL SEE A SHIFT TO
THE NORTHWEST LATER IN THE PERIOD AS A FRONTAL BOUNDARY MOVES INTO
THE REGION.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CK
SHORT TERM...TM
LONG TERM...LTH
AVIATION...CK
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1135 PM CDT FRI AUG 16 2013
.UPDATE...
ISSUED AT 1135 PM CDT FRI AUG 16 2013
TEMPS HAVE BEEN FALLING A BIT FASTER THAN EXPECTED IN THE
NORTHWESTERN COUNTIES...SO CUT LOWS A FEW DEGREES IN THAT AREA.
WINDS CONTINUE TO BE SOUTHERLY IN DIRECTION...AND THERE HAS BEEN
SOME DECENT MIXING. DEW POINT DEPRESSIONS HAVE BEEN CLOSE TO ZERO
AROUND VALLEY CITY AND COOPERSTOWN. STILL THINK THAT THE BEST
CHANCE FOR FOG WILL BE IN THE JAMES RIVER VALLEY...BUT SOME IN OUR
SOUTHWESTERN COUNTIES IS NOT OUT OF THE QUESTION. INCLUDED A BRIEF
PATCHY MENTION DURING THE EARLY MORNING HOURS.
UPDATE ISSUED AT 932 PM CDT FRI AUG 16 2013
NO MAJOR CHANGES TO THE CURRENT FORECAST. TEMPS STILL SEEM ON
TRACK TO DROP INTO THE 50S IN THE EAST TO LOW 60S OVERNIGHT. SOME
OF THE MODELS SUCH AS THE HRRR AND NAM ARE SHOWING SOME FOG
FORMATION OVER THE JAMES VALLEY WHICH THEN MOVES INTO OUR
SOUTHWESTERN COUNTIES BRIEFLY LATER TONIGHT. SOUTHWESTERLY WINDS
WILL BE PICKING UP AND THINK THAT MIXING WILL KEEP MUCH FOG FROM
FORMING AND WILL LEAVE OUT OF GRIDS FOR NOW. THINK THERE COULD BE
SOME STRATUS THROUGH SO KEPT SOME CLOUDS IN THE FAR SOUTH.
UPDATE ISSUED AT 627 PM CDT FRI AUG 16 2013
ONLY CHANGES WERE TO TWEAK CLOUD COVER A BIT AS SOUTHERN COUNTIES
HAVE HAD A BIT MORE CU THAN EXPECTED THIS EVENING. THINK THAT
SKIES WILL BECOME MOSTLY CLEAR AFTER SUNSET...BUT WILL HAVE TO
WATCH THE SOUTH FOR ANY STRATUS MOVING UP OUT OF SD.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 242 PM CDT FRI AUG 16 2013
CURRENT VIS IMAGERY SHOWING SCT CU DECK HAS EXPANDED WESTWARD INTO
SOUTHEASTERN ND. MOSTLY CLEAR ELSEWHERE. THERE IS MORE EXTENSIVE
SKY COVER OVER EASTERN SD AND FAR SW MINNESOTA....HOWEVER THE
NORTHERN EDGE CONTINUES TO BECOME MORE CELLULAR. MAIN CHALLENGE
TONIGHT WILL BE TEMPERATURES AND WHETHER OR NOT THE LOW LEVEL SW
FLOW WILL ADVECT ANY OF THIS MOISTURE INTO MY SOUTHEASTERN ZONES.
MODELED RH IN GENERAL AGREEMENT WITH BRINGING CLOUD COVER
NORTHWARD BUT NO SIGNS OF CLOUDS ON GFS/NAM MOS GUIDANCE.
LATE AFTERNOON AND TONIGHT...FOR CLOUD SITUATION...THINK LAST
COUPLE HOURS OF HEATING THIS AFTN WILL CONTINUE TO BREAK CLOUDS UP
ENOUGH OVER SD THAT THEY WILL DISSIPATE IN THE EARLY EVENING AND
WE WILL BE CLEAR TONIGHT ACROSS THE AREA. OVERNIGHT LOWS WILL BE A
BIT WARMER THAN LAST NIGHT WITH SOUTHERLY FLOW EXPECTED THROUGH
THE NIGHT.
SATURDAY AND SATURDAY NIGHT...FULL SOLAR...BREEZY SOUTHWEST WINDS AND
INCREASED MIXING AS WELL AS RISING H850 TEMPS WILL RESULT IN THE
FIRST ABOVE NORMAL TEMPS FOR AUGUST 2013. COULD EVEN HIT 90 IN
WARM AREAS AROUND THE VALLEY. MODELS ARE SHOWING A CHANCE FOR SOME
SHOWERS OR A STORM TO DEVELOP MAINLY ACROSS THE NORTH AND AFTER
09Z. HOWEVER MAIN ENERGY WITH UPPER WAVE SHOULD BE ACROSS SOUTHERN
MANITOBA AND WILL KEEP CWA DRY TONIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 242 PM CDT FRI AUG 16 2013
SUNDAY AND MONDAY...ANOTHER WARM DAY IS EXPECTED WITH
INSTABILITY INCREASING IN THE AFTERNOON BUT A SOLID CAP IN PLACE.
MERIDIONAL FLOW WILL BRING SEVERAL MINOR WAVES ACROSS THE
AREA...HOWEVER TIMING NOT CONSISTENT ENOUGH AMONGST THE MODELS TO
ADD ANY POPS THROUGH 00Z MON. BEST CHANCE WILL BE IN THE EVENING
IF AND WHEN THE CAP ERODES. WITH MAIN H850 FLOW OVER THE WKND OUT
OF WESTERN TX/NM VS AN OPEN GULF OF MEXICO...NOT SURE DEW POINTS
WILL GET HIGH ENOUGH DRG DAY SUNDAY TO GIVE US A SIGNIFICANT
CHANCE OF CONVECTION SUN EVENING HOWEVER WITH GFS SHOWING A STRONG
VORT MOVING ACROSS (BUT OVERDOING CONVECTION)...WILL STICK WITH
CONTINUITY AND MAINTAIN CHANCE POPS MAINLY ACROSS THE SOUTH. ONCE
AGAIN CONFIDENCE FOR ANYTHING SIGNIFICANT IS LOW ATTM. EXPECT
MONDAY TO BE DRY.
MONDAY THROUGH FRIDAY...MODELS ARE DECENT WITH OVERALL FEATURES WITH
SOME DIFFERENCES TO TIMING OF CONVECTIVE CHANCES. THE GFS/ECMWF
WANTS TO DEVELOP SOME STORMS BY WED/THU...WITH THE GEM REMAINING
DRY THROUGH THE PERIOD. THERE WILL BE VERY WARM TEMPS ALOFT AND
TEMPS WILL REMAIN WELL ABOVE NORMAL. IF THE ATMOSPHERE REMAINS
CAPPED...THEN THIS WOULD LIMIT CONVECTIVE CHANCES. WE HAVE ALSO
BEEN DRY FOR SOME TIME...AND OVERALL EVAPOTRANSPIRATION WILL BE
QUITE LOW. IN ADDITION...THE GULF OF MEXICO REMAINS SHUT OFF...SO
THIS COULD ALSO LIMIT SHOWER/STORMS UNTIL A STRONGER WAVE MOVES
OVER THE AREA. WILL CONTINUE WITH LOWER CHANCES FOR STORMS BY MID
WEEK...ALTHOUGH CONFIDENCE IS NOT VERY HIGH FOR WIDESPREAD
RAINFALL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1135 PM CDT FRI AUG 16 2013
ANY LOWER CIGS AND VIS SHOULD STAY SOUTH OF THE TAF SITES WITH VFR
CONDITIONS PREVAILING AND SOME MID AND HIGH CLOUDS. SOUTH WINDS
AROUND 10 KTS WILL PICK UP BY MID MORNING WITH GUSTS UP TO 25 KTS
POSSIBLE. WINDS SHOULD DIMINISH AGAIN TOMORROW EVENING.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...JR
SHORT TERM...SPEICHER
LONG TERM...DK/SPEICHER
AVIATION...JR
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1013 PM EDT SUN AUG 18 2013
.SYNOPSIS...
SEVERAL WEAK WEATHER SYSTEMS WILL DRIFT SLOWLY THROUGH THE GREAT
LAKES FROM TONIGHT THROUGH MID-WEEK...AS TEMPERATURES AND
HUMIDITY CONTINUE TO SLOWLY INCREASE AT THE SAME TIME. NEITHER OF
THE DISTURBANCES IS EXPECTED TO BRING MUCH COVERAGE OF RAIN...BUT
THREATS FOR SHOWERS OR A FEW THUNDERSTORMS ON A LIMITED BASIS WILL
BE PRESENT TONIGHT INTO MONDAY MAINLY EAST OF I-71...AND ON
WEDNESDAY ESPECIALLY SOUTH OF I-70. IN BOTH CASES...MOST AREAS
WILL STAY DRY...WITH MUGGY AND WARM AFTERNOONS AND MILD NIGHTS WITH
LIGHT WINDS. ABOVE NORMAL TEMPERATURES WILL REMAIN ENTRENCHED
THROUGH THE WEEK INTO NEXT WEEKEND...AS A VERY TYPICAL LATE SUMMER
PATTERN REMAINS IN PLACE.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
UPDATED TONIGHT TO REMOVE ALL PRECIPITATION FOR THE OVERNIGHT
HOURS. WITH LOSS OF HEATING OF THE DAY AND WEAK FORCING
REMAINING...THERE IS ONLY SMALL CHANCE OF SHOWERS. ALSO ADJUSTED
SKY COVER FOR CURRENT TRENDS. NO OTHER SIGNIFICANT CHANGES WERE
MADE WITH THIS UPDATE.
AFTERNOON DISCUSSION FOLLOWS BELOW....
DISORGANIZED SHIELD OF VERY LIGHT
RAIN/SPRINKLES HAS BEEN PUSHING STEADILY NORTHEAST THROUGH THE
AFTERNOON UP THE SCIOTO RIVER VALLEY...IMMEDIATELY IN ADVANCE OF A
MID-LEVEL VORTICITY MAX SEEN SWIRLING BOTH ON VISIBLE SATELLITE
IMAGERY AND ON RADAR MOSAICS OVER NRN KENTUCKY. THIS IS NEAR THE
NOSE OF A NARROW 250MB JETLET /115KT/ THAT IS SHIFTING NORTHEAST
AND ALLOWING THE OPENING/SHEARING OF THE OLD CLOSED LOW THAT HAD
BEEN SPINNING WELL SOUTHWEST OF THE AREA THE PAST FEW DAYS. THE
MID/UPPER LEVEL SHORTWAVE TROUGH IS POSITIVELY TILTED...AND
WEAKENING WITH TIME...WITH DECREASING LARGE SCALE ASCENT AND VERY
WEAK SURFACE FEATURES UNDERNEATH. THE 18.18Z RAP HAD A NICE HANDLE
ON THE MID LEVEL VORT MAX DRIVING NORTHEAST THROUGH SCNTL OH...AND
CONTINUES TO LIFT THIS FEATURE OUT OF THE AREA THROUGH MID
EVENING...WITH THE SHIELD OF LIGHT RAIN/SPRINKLES LIKELY EXITING
THE AREA BY 00Z OR SO...IF IT DOESN/T FALL APART COMPLETELY BEFORE
THEN. MESOANALYSIS CURRENTLY /19Z/ SHOWS A FAIRLY NICE
DIFFERENTIAL HEATING ZONE /CAPE AXIS/ ON THE IMMEDIATE WEST SIDE
OF THE RAIN SHIELD...RUNNING FROM OWEN/GRANT COUNTIES UP THROUGH
THE WILMINGTON AREA TOWARDS CMH. VARIOUS AND SUNDRY CONVECTION
ALLOWING MODEL RUNS /3-4KM RESOLUTION/ HAVE TRIED TO DEVELOP
ISOLATED STORMS IN THIS CORRIDOR IN THE NEXT FEW HOURS UP THROUGH
ABOUT 02Z...SO WE ARE IN NO HURRY TO DECREASE/SHRINK RAIN CHANCES
WEST OR SOUTHWEST OF CURRENT RAIN SHIELD OVER SCNTL OH. WHILE
MLCAPE IS LARGELY WEAK /300-700 J/KG/...THE PASSING OF THE
MID/UPPER LEVEL PV ANOMALY ACROSS THIS AREA THROUGH THE NEXT FEW
HOURS MAY AGITATE THE WEAK BAROCLINIC ZONE FOR A STORM OR TWO.
LATER THIS EVENING/OVERNIGHT...ONE MORE SURGE /IF YOU CAN CALL IT
THAT - IT IS QUITE WEAK/ OF MOISTURE ADVECTION RIDES FROM ERN
TN/KY INTO CNTL/ERN OH AND MAY PROMOTE SOME -SHRA REGENERATION
OVER THE SCIOTO VALLEY AND UP TOWARD/EAST OF CMH...SO WE HOLD ON
TO HIGHER RAIN CHANCES HERE LATER THIS EVENING AND OVERNIGHT. NOT
SURE IF THIS WILL LEAD TO MUCH ACTIVITY OR NOT...CONFIDENCE IS
LOW...BUT THE SIGNAL HAS BEEN PRESENT FOR A FEW DAYS THUS DON/T
WANT TO BACK AWAY YET. KEPT MIN TEMP FORECAST RIGHT WHERE IT WAS
FOR THE MOST PART...WELL TRENDED IN THE LOWER 60S MOST
AREAS...THOUGH MIXED OUT DEW POINTS IN WCNTL OHIO/ERN IND SUGGEST
SOME MID TO UPPER 50S IN THAT AREA WHERE PRECIPITABLE WATER
MINIMUM EXISTS.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
THE LAST WEAK SURGE OF MOISTURE MAY LINGER SHOWER CHANCES IN THE
EAST IN THE MORNING...AND THERE MAY BE JUST ENOUGH DIURNAL INSTBY
FOR A SHOWER/STORM IN THE FAR EAST/SOUTH IN THE AFTERNOON...BUT
MONDAY IS LARGELY A DRY DAY FOR THE FORECAST AREA WITH INCREASING
SUBSIDENCE IN THE WAKE OF THE DEPARTING SHORTWAVE TROUGH WHICH
WILL BE SHEARING DOWNSTREAM THROUGH PA/NY. DESPITE ITS
DEPARTURE...THERE REMAINS A WEAKNESS IN THE LARGER SCALE HEIGHT
FIELD BETWEEN TWO LARGE ANTICYCLONES OFF THE SOUTHEAST CONUS AND
OVER THE CNTL CONUS. THIS WEAKNESS IS A SOURCE OF LINGERING WEAK
SHORTWAVE ENERGY...AND WITH THIS AXIS LINGERING IN THE FAR
SOUTH/EAST...THUS THE SMALL RAIN CHANCES LINGERING UNTIL THAT AXIS
CAN CLEAR IN THE MID AFTERNOON HOURS. MOST AREAS WILL SEE A FAIR
AMOUNT OF SUNSHINE ON MONDAY...WITH TEMPS ADDING A FEW MORE
DEGREES TO PUT MOST AREAS IN THE LOW-MID 80S.
BRIEF SHORTWAVE RIDGING SLIDES IN FOR MONDAY NIGHT...WITH SKIES
GOING CLEAR. THIS SHOULD ALLOW A LITTLE BETTER TEMP DROP WITH
PWAT DROPPING OFF BACK TOWARD 1 INCH /BELOW SEASONAL NORMS/.
THUS...SIDED WITH SOME OF THE MOS DATASETS THAT ALLOWED COOL SPOTS
TO DROP OFF PRETTY DECENTLY MON NIGHT INTO THE UPPER 50S. WITH
SUCH LIGHT WINDS OVER THE NEXT COUPLE NIGHTS...ALMOST CERTAIN TO
BE COMMON SUMMER NIGHT FOG IN LOW LYING AREAS...BUT NOT SEEING A
GREAT SIGNAL FOR SOMETHING WIDESPREAD TO INCLUDE IN THE FORECAST
AS OF YET.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
SURFACE HIGH PRESSURE WILL ESTABLISH ITSELF TO OUR SE ON TUESDAY IN
WAKE OF DEPARTING UPR LVL SYSTEM. WE SHOULD SEE A MOSTLY SUNNY TO
PARTLY SUNNY DAY. MODELS HAD BEEN SUGGESTING THAT PERHAPS A POP OF
SHOWER OR STORM COULD OCCUR IN THE FAR SOUTH DURING THE HEAT OF THE
DAY. THIS STILL MAY OCCUR...BUT DO NOT FEEL IT WARRANTS A 20 POP
MENTION SO HAVE ALLOW THE FORECAST TO REMAIN DRY. HIGHS WILL BE A
LITTLE WARMER...GENERALLY IN THE MID 80S.
FOR THE PERIOD TUESDAY NIGHT INTO WEDNESDAY NIGHT...MAJORITY OF
MODELS HAVE COME MORE IN LINE ON WHAT WILL HAPPEN TO EMBEDDED S/WV
ENERGY WITHIN THE NW FLOW ALOFT. IT APPEARS THIS ENERGY WILL DEVELOP
INTO A CLOSED LOW TO OUR WEST...THEN WILL SLOWLY PROGRESS EAST THROUGH
THE REGION WEDNESDAY INTO WEDNESDAY NIGHT. ECMWF/GFS SUGGEST THAT
SOME EMBEDDED S/WV ENERGY MOVING NE AROUND DEVELOPING CLOSED LOW
COULD SPARK A FEW SHOWERS AND THUNDERSTORMS BEGINNING ACRS OUR SW
TUESDAY NIGHT. HAVE GIVEN ALL LOCATIONS AT LEAST A THREAT FOR
SHOWERS AND STORMS ON WEDNESDAY WITH THE HIGHER CHANCES FAVORING THE
SRN ZONES DUE TO HIGHER INSTABILITY AND MOISTURE. HAVE ALLOWED POPS
TO FALL OFF OVERNIGHT WEDNESDAY NIGHT AS SYSTEM HEADS EAST. HIGHS ON
WEDNESDAY WILL BE SLIGHTLY COOLER...ESPECIALLY SOUTHWEST CLOSER TO
THE UPR LVL LOW.
FOR THE PERIOD THURSDAY INTO FRIDAY NIGHT...MODELS CONTINUE TO
STRUGGLE ON HOW LONG WAVE TROUGH ENERGY WILL DIG SE INTO SE CANADA
AND NEW ENGLAND DURING THE PERIOD. AS SUCH...ASSOCIATED COLD FRONT
AND WHERE IT WILL END UP...I.E. WILL IT PUSH THROUGH...STALL OUT
OVER OUR AREA...OR PERHAPS FALL APART...IS STILL IN QUESTION. HAVE
TAKEN A BLEND OF WPC AND THE LATEST 18.12Z ECMWF...WHICH ALLOWS THE
FRONT TO APPROACH THE REGION FROM THE NORTH THURSDAY NIGHT...SLOW IT
UP AS IT PUSHES INTO THE REMAINDER OF THE AREA ON FRIDAY...THEN
WASHES IT OUT FRIDAY NIGHT INTO SATURDAY AS ANOTHER HIGH PRESSURE
RIDGE BUILDS IN FROM THE NORTH. GIVEN LACK OF STRONG UPR
SUPPORT...AS IT IS FCST TO REMAIN WELL OFF TO THE NE...ALONG WITH
WEAK LOW LEVEL FORCING...HAVE KEPT POPS LOW THURSDAY NIGHT INTO
FRIDAY. HAVE THEN ALLOWED CONDITIONS TO DRY OUT BY FRIDAY NIGHT.
TEMPERATURES WILL BE CLOUD DEPENDENT BUT SHOULD SEE A SLIGHT BUMP UP
AHEAD OF THE FRONT ON THURSDAY WITH SIMILAR OR SLIGHTLY COOLER
CONDITIONS POSSIBLE ON FRIDAY.
SURFACE HIGH PRESSURE WILL MOVE EAST THROUGH THE UPCOMING WEEKEND AS
A MID LVL RIDGE BEGINS TO NUDGE INTO FROM THE CNTRL PLAINS.
CONDITIONS SHOULD REMAIN DRY. TEMPERATURES WILL BE SEASONABLY WARM
FOR LATE AUGUST.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
SHOWERS HAVE DISSIPATED ACROSS MUCH OF CENTRAL OHIO THIS EVENING.
EARLY THIS EVENING AN AREA OF SCATTERED SHOWERS AND THUNDERSTORMS
WAS MOVING NE TOWARD ILN/S NORTHERN KY COUNTIES...HOWEVER THIS
CONVECTION SHOULD MISS ANY TAF SITES BEFORE DISSIPATING. THE
CLOSED LOW THAT HAS BEEN SPINNING WELL SW OF THE AREA THE PAST FEW
DAYS WILL CONTINUE TO OPEN AND SHEAR OVER THE NEXT 12 TO 18 HOURS.
THE MID/UPPER LEVEL SHORTWAVE TROUGH IS POSITIVELY TILTED AND
WEAKENING WITH TIME AS IT MOVES EAST...PROVIDING LESS SUPPORT FOR
ANY SHOWERS/THUNDERSTORMS FOR THE REMAINDER OF THE TAF PERIOD. WHILE
THERE IS A SLIGHT CHANCE OF SEEING A SHOWER IN THE EAST LATER
TONIGHT...OPTED TO KEEP ALL TAFS DRY THROUGH THE FORECAST PERIOD.
WITH THE LOSS OF DAYTIME HEATING...THE CU FIELD DIMINISHED. CLEARING
AND LIGHT WINDS ARE EXPECTED AT TAF SITES OVERNIGHT AND THIS WILL
BRING THE POSSIBILITY OF MVFR VSBYS IN FOG FROM 19/09Z TO 19/13Z.
KLUK AND KILN MAY DEVELOP IFR VSBYS IN FOG BUT NOT CONFIDENT
ENOUGH TO INCLUDE IN FORECAST AT THIS TIME.
VFR CONDITIONS EXPECTED AFTER 19/13Z WITH SCATTERED CU DEVELOPING.
OUTLOOK...NO SIGNIFICANT WEATHER EXPECTED.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...BINAU
NEAR TERM...BINAU/PARKER
SHORT TERM...BINAU
LONG TERM...HICKMAN
AVIATION...PARKER
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
953 PM EDT SUN AUG 18 2013
.SYNOPSIS...
UPPER LEVEL TROUGH...AND ASSOCIATED MID LEVEL SHORT WAVES CROSS
THROUGH MONDAY. SFC HIGH PRESSURE REMAINS THROUGH MID WEEK. COLD
FRONT STALLS NORTH BY LATE WEEK. HIGH PRESSURE FOR NEXT WEEKEND.
&&
.NEAR TERM /THROUGH MONDAY/...
UPDATED SKIES...POPS...TEMPS...DEWPOINTS...AND WEATHER PER LATEST
RADAR...SATELLITE AND SFC OBSERVATIONS. MODELS CONTINUE TO SHOW
VORT MAXES PASSING FROM SOUTHWEST TO NORTHEAST ACROSS THE AREA
OVERNIGHT. AN UPPER LEVEL JET STREAK EXCEEDING 80 KNOTS IS EVIDENT
IN MODELS AND WATER VAPOR IMAGES...EXPECTED TO MOVE OVERHEAD
OVERNIGHT. HOWEVER...WITH THE LACK OF HEATING...EXPECT ISOLATED
TO SCATTERED SHOWERS THROUGH THE EARLY MORNING HOURS. DEWPOINT
DEPRESSION WILL BE 1 OR 2 DEGREES APART...MEANWHILE...POCKETS OF
CLEAR SKIES OR VERY HIGH LEVEL CLOUDS DEVELOP. BOUNDARY LAYER FLOW
REMAINS NEAR 10 KNOTS PER THE NAM...AND AT OR BELOW 5 KNOTS PER
THE RUC13. THIS SCENARIO COULD RESULT IN WIDESPREAD DENSE
FOG...ESPECIALLY OVER AREAS THAT RECEIVED RAIN.
DEPENDING ON CLOUD COVER EARLY MONDAY MORNING...FOG MAY HANG
LONGER ACROSS PROTECTED VALLEYS.
INTERPOLATED LATEST SFC OBS WITH THE 23Z RUN RUC13 FOR
TEMPERATURES THROUGH 12Z MONDAY.
PREVIOUS DISCUSSION BELOW...
UPPER LEVEL S/W TROUGH APPROACHES TONIGHT AND THEN CROSSES MON.
DISTURBANCE RIDING UP ALONG THE SW FLOW AHEAD OF THE TOUGH CROSSING
THE AREA THIS AFTERNOON EXITS NE TONIGHT...RESULTING IN A DECREASE
OF AREA COVERAGE OF RAIN. ABUNDANT CLOUD AND THE RAIN PRECLUDED SFC
HEATING TODAY. STILL HAVE THE SMALL CHANCE FOR A LATE THUNDERSTORM
TODAY...BUT THE POTENTIAL IS MUCH LOWER NOW.
A SMALL PORTION OF N CENTRAL WV GOT HIT HARD WITH RAIN LAST NIGHT.
GRANTSVILLE IN CALHOUN COUNTY CAME IN WITH 2.56 INCHES IN 24 HRS
ENDING 12Z THIS MORNING. THIS WAS CLOSE TO IN MAGNITUDE BUT S OF
THE DP STORM TOTAL BULLSEYE...WITH VALUES CLOSER TO 1.50 AT
GRANTSVILLE. LEGACY STORM TOTAL WAS ABOUT 60 PERCENT OF DP. THE
AREA WILL NEED WATCHED FOR A HEAVIER THUNDERSTORM INTO THIS EVENING.
A SECOND WAVE RIDES UP THE MOUNTAINS MON MORNING. MODEST
INSTABILITY THROUGHOUT THE AREA WITH BREAKS OF SUNSHINE UNDER THE
PASSING S/W TROUGH MON AFTERNOON GIVES RISE TO THE THUNDERSTORM
CHANCE.
TEMPERATURES TODAY NEEDED LOWERED. LOWS TONIGHT WERE IN LINE WITH
THE MET WHICH LOOKED REASONABLE. BLENDED IN THE MET TO RAISE HIGHS
A BIT MON...MAINLY W.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
QUIETER WEATHER IN THE SHORT TERM PERIOD. WARMER...AND MORE HUMID
WEATHER WILL BE THE RULE ON TUESDAY...WITH SURFACE HIGH OVER THE
REGION...AND BUILDING UPPER HEIGHTS OUT AHEAD OF AN UPPER SHORTWAVE
TROUGH WHICH WILL MOVE INTO THE AREA IN THE WEDNESDAY NIGHT/THURSDAY
TIME FRAME. WITH A CLEARING SKY MONDAY NIGHT...AND SURFACE HIGH OVER
THE AREA...EXPECT RIVER VALLEY FOG DEVELOPMENT TUESDAY
MORNING...PARTICULARLY ACROSS SOUTHEAST OHIO...EASTERN KY...AND
ADJACENT WV COUNTIES WHERE BETTER CLEARING IS LIKELY TO TAKE PLACE.
WITH THE INCREASED HEAT AND HUMIDITY ON TUESDAY...EXPECT ISOLD
DIURNAL THUNDERSTORMS...MAINLY ACROSS SOUTHERN ZONES...BUT MUCH OF
AREA WILL REMAIN DRY. KEPT POPS AT SLIGHT CHANCE ON TUESDAY.
UPPER SHORTWAVE TROUGH TRIES TO NUDGE EAST TOWARDS THE CWA ON
WEDNESDAY. THIS WILL ALLOW FOR A GREATER CHANCE OF POPS AS COMPARED
TO TUESDAY...AND SLIGHTLY COOLER TEMPERATURES THAN TUESDAY. FLOW
WILL REMAIN RELATIVELY LIGHT...AND WITH PW VALUES EXPECTED TO ONCE
AGAIN CLIMB TO AROUND 1.6 INCHES...COULD SEE ISOLD SPOTS OF HEAVY
RAIN/POTENTIAL WATER ISSUES IN PRONE AREAS. WILL ALSO KEEP MENTION
OUT OF THE HWO FOR NOW AS DONT FEEL THE THREAT IS ENOUGH TO WARRANT
A FFA ON WEDNESDAY.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
PROGRESSIVELY MORE UNCERTAIN MODEL SOLUTIONS THROUGH THE PERIOD LED
TO A MODEL BLEND...GIVING SLIGHTLY MORE FAVOR TO THE ECMWF...UPPER
TROUGH WEDNESDAY NIGHT MOVES OFF SHORE BY FRI MORNING WITH NORTHWEST
FLOW AND EMBEDDED SHORTWAVES IN ITS WAKE...AMPLIFIED UPPER RIDGE
BUILDS OVER THE EASTERN US BY SUNDAY EVENING...BEST CHANCE FOR
PRECIP IS ACROSS NORTH/CENTRAL WV LATE WED/EARLY THUR WITH EXITING
TROUGH RESULTING IN MARGINAL UPPER LEVEL FORCING...OTHERWISE SLIGHT
CHANCE OF DIURNAL/OROGRAPHIC FORCED PRECIP IN THE EASTERN MTN AREAS
LATER THURS AND FRI AFTERNOON...APPEAR TO DRY OUT NICELY FOR NEXT
WEEKEND IN INCREASINGLY STABLE AIR MASS.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
MVFR/IFR CONDITIONS EXPECTED ALONG THE EASTERN MOUNTAIN TONIGHT AS
ISOLATED TO SCATTERED SHOWERS CONTINUE TO MOVE NORTH NORTHEAST...TO
IMPACT BKW...EKN AND CKB WITH LIGHT RAIN OVERNIGHT.
POCKETS OF CLEAR SKIES...OR VERY HIGH CIRRUS COULD ALLOW FOR FOG
FORMATION AS TEMPERATURES DROP TO THEIR DEWPOINTS EARLY TONIGHT.
NAM AND RUN MODELS SHOW LIGHT LIGHT TO CALM FLOW IN THE BOUNDARY
LAYER AND DEWPOINTS OVERNIGHT SHOULD STAY IN THE MID TO UPPER 60S.
EXPECT IFR/LIFR CONDITIONS UNDER DENSE FOG AT CRW...HTS...AND PKB
OVERNIGHT.
IFR LOW STRATUS IS ALSO POSSIBLE IF UPPER TO MIDDLE LEVEL CLOUDS
DEVELOP IN RESPONSE OF VORTICITY MAX AT H5 PASSING THROUGH...AND
AN A H3 JET STREAK OVERHEAD THROUGH 12Z MONDAY.
FOG AND LOW STRATUS WILL BE SLOWER TO BURN OFF OR MIX OUT MONDAY
MORNING ON ACCOUNT OF THE ABUNDANT LOW LEVEL MOISTURE.
SFC FLOW WILL BE LIGHT AND VARIABLE...MAINLY SOUTHWEST MONDAY...AS
A SURFACE HIGH PRESSURE SYSTEM DOMINATES THE LOWER LEVELS.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z TUESDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING AND LOCATION OF FOG OR LOW STRATUS...WILL
VARY DEPENDING OF UPPER TO MID LEVEL CLOUDS.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE MON 08/19/13
UTC 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13
EDT 1HRLY 22 23 00 01 02 03 04 05 06 07 08 09
CRW CONSISTENCY H M H L L L L L L L L L
HTS CONSISTENCY H M H L L L L L L L L L
BKW CONSISTENCY M M M M H H H H H H H H
EKN CONSISTENCY M L L L L L L L L H H M
PKB CONSISTENCY M L L L L L L L L L L L
CKB CONSISTENCY M M M H H H H M M H H H
AFTER 00Z TUESDAY...
AREAS OF IFR IN DENSE FOG MOST MORNINGS THIS WEEK...ESPECIALLY ALONG
THE RIVERS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...ARJ/TRM/SL
NEAR TERM...ARJ/TRM
SHORT TERM...SL
LONG TERM...JM
AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
758 PM EDT SUN AUG 18 2013
.SYNOPSIS...
SEVERAL WEAK WEATHER SYSTEMS WILL DRIFT SLOWLY THROUGH THE GREAT
LAKES FROM TONIGHT THROUGH MID-WEEK...AS TEMPERATURES AND
HUMIDITY CONTINUE TO SLOWLY INCREASE AT THE SAME TIME. NEITHER OF
THE DISTURBANCES IS EXPECTED TO BRING MUCH COVERAGE OF RAIN...BUT
THREATS FOR SHOWERS OR A FEW THUNDERSTORMS ON A LIMITED BASIS WILL
BE PRESENT TONIGHT INTO MONDAY MAINLY EAST OF I-71...AND ON
WEDNESDAY ESPECIALLY SOUTH OF I-70. IN BOTH CASES...MOST AREAS
WILL STAY DRY...WITH MUGGY AND WARM AFTERNOONS AND MILD NIGHTS WITH
LIGHT WINDS. ABOVE NORMAL TEMPERATURES WILL REMAIN ENTRENCHED
THROUGH THE WEEK INTO NEXT WEEKEND...AS A VERY TYPICAL LATE SUMMER
PATTERN REMAINS IN PLACE.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A QUICK UPDATE EARLY THIS EVE TO CLEAN UP SKY/RAIN CHANCE IN
ACCORDANCE WITH SATELLITE/RADAR TRENDS. PREVIOUS SCNTL OHIO RAIN
AREA HAS FIZZLED QUICKLY SO LOWERED EARLY-MID EVENING RAIN CHANCES
THERE. ALSO ACCOUNTED FOR POSSIBILITY THAT PULSEY/DISORGANIZED
UPDRAFTS OVER CNTL KY MAY WANDER INTO OWEN/GRANT COUNTIES THROUGH
01Z. RECENT HRRR RUNS HAVE BACKED AWAY FROM ISOLD CONVECTION ALONG
THE DIFFERENTIAL HEATING ZONE ON THE EDGE OF THE AFTN THICKER
CLOUD SHIELD FROM OWEN/GRANT UP THROUGH CLINTON COUNTY...THOUGH
LOW LEVEL MOISTURE IS POOLED HERE...WITH DWPT AT KILN AT 66F. CHCS
FOR DIURNALLY TIED CONVECTION HAVE WANED CONSIDERABLY GIVEN
SATELLITE TRENDS...SO RAIN CHANCES REDUCED HERE FOR THE EVENING.
ALSO...BASED ON LATEST DATA...THE LATE EVE/OVERNIGHT RAIN CHANCES
IN THE SCIOTO VALLEY AND UP TOWARD LICKING COUNTY MAY NEED TO BE
PULLED ALTOGETHER. WILL MONITOR.
PREVIOUS DISCUSSION FOLLOWS BELOW....
DISORGANIZED SHIELD OF VERY LIGHT
RAIN/SPRINKLES HAS BEEN PUSHING STEADILY NORTHEAST THROUGH THE
AFTERNOON UP THE SCIOTO RIVER VALLEY...IMMEDIATELY IN ADVANCE OF A
MID-LEVEL VORTICITY MAX SEEN SWIRLING BOTH ON VISIBLE SATELLITE
IMAGERY AND ON RADAR MOSAICS OVER NRN KENTUCKY. THIS IS NEAR THE
NOSE OF A NARROW 250MB JETLET /115KT/ THAT IS SHIFTING NORTHEAST
AND ALLOWING THE OPENING/SHEARING OF THE OLD CLOSED LOW THAT HAD
BEEN SPINNING WELL SOUTHWEST OF THE AREA THE PAST FEW DAYS. THE
MID/UPPER LEVEL SHORTWAVE TROUGH IS POSITIVELY TILTED...AND
WEAKENING WITH TIME...WITH DECREASING LARGE SCALE ASCENT AND VERY
WEAK SURFACE FEATURES UNDERNEATH. THE 18.18Z RAP HAD A NICE HANDLE
ON THE MID LEVEL VORT MAX DRIVING NORTHEAST THROUGH SCNTL OH...AND
CONTINUES TO LIFT THIS FEATURE OUT OF THE AREA THROUGH MID
EVENING...WITH THE SHIELD OF LIGHT RAIN/SPRINKLES LIKELY EXITING
THE AREA BY 00Z OR SO...IF IT DOESN/T FALL APART COMPLETELY BEFORE
THEN. MESOANALYSIS CURRENTLY /19Z/ SHOWS A FAIRLY NICE
DIFFERENTIAL HEATING ZONE /CAPE AXIS/ ON THE IMMEDIATE WEST SIDE
OF THE RAIN SHIELD...RUNNING FROM OWEN/GRANT COUNTIES UP THROUGH
THE WILMINGTON AREA TOWARDS CMH. VARIOUS AND SUNDRY CONVECTION
ALLOWING MODEL RUNS /3-4KM RESOLUTION/ HAVE TRIED TO DEVELOP
ISOLATED STORMS IN THIS CORRIDOR IN THE NEXT FEW HOURS UP THROUGH
ABOUT 02Z...SO WE ARE IN NO HURRY TO DECREASE/SHRINK RAIN CHANCES
WEST OR SOUTHWEST OF CURRENT RAIN SHIELD OVER SCNTL OH. WHILE
MLCAPE IS LARGELY WEAK /300-700 J/KG/...THE PASSING OF THE
MID/UPPER LEVEL PV ANOMALY ACROSS THIS AREA THROUGH THE NEXT FEW
HOURS MAY AGITATE THE WEAK BAROCLINIC ZONE FOR A STORM OR TWO.
LATER THIS EVENING/OVERNIGHT...ONE MORE SURGE /IF YOU CAN CALL IT
THAT - IT IS QUITE WEAK/ OF MOISTURE ADVECTION RIDES FROM ERN
TN/KY INTO CNTL/ERN OH AND MAY PROMOTE SOME -SHRA REGENERATION
OVER THE SCIOTO VALLEY AND UP TOWARD/EAST OF CMH...SO WE HOLD ON
TO HIGHER RAIN CHANCES HERE LATER THIS EVENING AND OVERNIGHT. NOT
SURE IF THIS WILL LEAD TO MUCH ACTIVITY OR NOT...CONFIDENCE IS
LOW...BUT THE SIGNAL HAS BEEN PRESENT FOR A FEW DAYS THUS DON/T
WANT TO BACK AWAY YET. KEPT MIN TEMP FORECAST RIGHT WHERE IT WAS
FOR THE MOST PART...WELL TRENDED IN THE LOWER 60S MOST
AREAS...THOUGH MIXED OUT DEW POINTS IN WCNTL OHIO/ERN IND SUGGEST
SOME MID TO UPPER 50S IN THAT AREA WHERE PRECIPITABLE WATER
MINIMUM EXISTS.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
THE LAST WEAK SURGE OF MOISTURE MAY LINGER SHOWER CHANCES IN THE
EAST IN THE MORNING...AND THERE MAY BE JUST ENOUGH DIURNAL INSTBY
FOR A SHOWER/STORM IN THE FAR EAST/SOUTH IN THE AFTERNOON...BUT
MONDAY IS LARGELY A DRY DAY FOR THE FORECAST AREA WITH INCREASING
SUBSIDENCE IN THE WAKE OF THE DEPARTING SHORTWAVE TROUGH WHICH
WILL BE SHEARING DOWNSTREAM THROUGH PA/NY. DESPITE ITS
DEPARTURE...THERE REMAINS A WEAKNESS IN THE LARGER SCALE HEIGHT
FIELD BETWEEN TWO LARGE ANTICYCLONES OFF THE SOUTHEAST CONUS AND
OVER THE CNTL CONUS. THIS WEAKNESS IS A SOURCE OF LINGERING WEAK
SHORTWAVE ENERGY...AND WITH THIS AXIS LINGERING IN THE FAR
SOUTH/EAST...THUS THE SMALL RAIN CHANCES LINGERING UNTIL THAT AXIS
CAN CLEAR IN THE MID AFTERNOON HOURS. MOST AREAS WILL SEE A FAIR
AMOUNT OF SUNSHINE ON MONDAY...WITH TEMPS ADDING A FEW MORE
DEGREES TO PUT MOST AREAS IN THE LOW-MID 80S.
BRIEF SHORTWAVE RIDGING SLIDES IN FOR MONDAY NIGHT...WITH SKIES
GOING CLEAR. THIS SHOULD ALLOW A LITTLE BETTER TEMP DROP WITH
PWAT DROPPING OFF BACK TOWARD 1 INCH /BELOW SEASONAL NORMS/.
THUS...SIDED WITH SOME OF THE MOS DATASETS THAT ALLOWED COOL SPOTS
TO DROP OFF PRETTY DECENTLY MON NIGHT INTO THE UPPER 50S. WITH
SUCH LIGHT WINDS OVER THE NEXT COUPLE NIGHTS...ALMOST CERTAIN TO
BE COMMON SUMMER NIGHT FOG IN LOW LYING AREAS...BUT NOT SEEING A
GREAT SIGNAL FOR SOMETHING WIDESPREAD TO INCLUDE IN THE FORECAST
AS OF YET.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
SURFACE HIGH PRESSURE WILL ESTABLISH ITSELF TO OUR SE ON TUESDAY IN
WAKE OF DEPARTING UPR LVL SYSTEM. WE SHOULD SEE A MOSTLY SUNNY TO
PARTLY SUNNY DAY. MODELS HAD BEEN SUGGESTING THAT PERHAPS A POP OF
SHOWER OR STORM COULD OCCUR IN THE FAR SOUTH DURING THE HEAT OF THE
DAY. THIS STILL MAY OCCUR...BUT DO NOT FEEL IT WARRANTS A 20 POP
MENTION SO HAVE ALLOW THE FORECAST TO REMAIN DRY. HIGHS WILL BE A
LITTLE WARMER...GENERALLY IN THE MID 80S.
FOR THE PERIOD TUESDAY NIGHT INTO WEDNESDAY NIGHT...MAJORITY OF
MODELS HAVE COME MORE IN LINE ON WHAT WILL HAPPEN TO EMBEDDED S/WV
ENERGY WITHIN THE NW FLOW ALOFT. IT APPEARS THIS ENERGY WILL DEVELOP
INTO A CLOSED LOW TO OUR WEST...THEN WILL SLOWLY PROGRESS EAST THROUGH
THE REGION WEDNESDAY INTO WEDNESDAY NIGHT. ECMWF/GFS SUGGEST THAT
SOME EMBEDDED S/WV ENERGY MOVING NE AROUND DEVELOPING CLOSED LOW
COULD SPARK A FEW SHOWERS AND THUNDERSTORMS BEGINNING ACRS OUR SW
TUESDAY NIGHT. HAVE GIVEN ALL LOCATIONS AT LEAST A THREAT FOR
SHOWERS AND STORMS ON WEDNESDAY WITH THE HIGHER CHANCES FAVORING THE
SRN ZONES DUE TO HIGHER INSTABILITY AND MOISTURE. HAVE ALLOWED POPS
TO FALL OFF OVERNIGHT WEDNESDAY NIGHT AS SYSTEM HEADS EAST. HIGHS ON
WEDNESDAY WILL BE SLIGHTLY COOLER...ESPECIALLY SOUTHWEST CLOSER TO
THE UPR LVL LOW.
FOR THE PERIOD THURSDAY INTO FRIDAY NIGHT...MODELS CONTINUE TO
STRUGGLE ON HOW LONG WAVE TROUGH ENERGY WILL DIG SE INTO SE CANADA
AND NEW ENGLAND DURING THE PERIOD. AS SUCH...ASSOCIATED COLD FRONT
AND WHERE IT WILL END UP...I.E. WILL IT PUSH THROUGH...STALL OUT
OVER OUR AREA...OR PERHAPS FALL APART...IS STILL IN QUESTION. HAVE
TAKEN A BLEND OF WPC AND THE LATEST 18.12Z ECMWF...WHICH ALLOWS THE
FRONT TO APPROACH THE REGION FROM THE NORTH THURSDAY NIGHT...SLOW IT
UP AS IT PUSHES INTO THE REMAINDER OF THE AREA ON FRIDAY...THEN
WASHES IT OUT FRIDAY NIGHT INTO SATURDAY AS ANOTHER HIGH PRESSURE
RIDGE BUILDS IN FROM THE NORTH. GIVEN LACK OF STRONG UPR
SUPPORT...AS IT IS FCST TO REMAIN WELL OFF TO THE NE...ALONG WITH
WEAK LOW LEVEL FORCING...HAVE KEPT POPS LOW THURSDAY NIGHT INTO
FRIDAY. HAVE THEN ALLOWED CONDITIONS TO DRY OUT BY FRIDAY NIGHT.
TEMPERATURES WILL BE CLOUD DEPENDENT BUT SHOULD SEE A SLIGHT BUMP UP
AHEAD OF THE FRONT ON THURSDAY WITH SIMILAR OR SLIGHTLY COOLER
CONDITIONS POSSIBLE ON FRIDAY.
SURFACE HIGH PRESSURE WILL MOVE EAST THROUGH THE UPCOMING WEEKEND AS
A MID LVL RIDGE BEGINS TO NUDGE INTO FROM THE CNTRL PLAINS.
CONDITIONS SHOULD REMAIN DRY. TEMPERATURES WILL BE SEASONABLY WARM
FOR LATE AUGUST.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
SHOWERS HAVE DISSIPATED ACROSS MUCH OF CENTRAL OHIO THIS EVENING.
EARLY THIS EVENING AN AREA OF SCATTERED SHOWERS AND THUNDERSTORMS
WAS MOVING NE TOWARD ILN/S NORTHERN KY COUNTIES...HOWEVER THIS
CONVECTION SHOULD MISS ANY TAF SITES BEFORE DISSIPATING. THE
CLOSED LOW THAT HAS BEEN SPINNING WELL SW OF THE AREA THE PAST FEW
DAYS WILL CONTINUE TO OPEN AND SHEAR OVER THE NEXT 12 TO 18 HOURS.
THE MID/UPPER LEVEL SHORTWAVE TROUGH IS POSITIVELY TILTED AND
WEAKENING WITH TIME AS IT MOVES EAST...PROVIDING LESS SUPPORT FOR
ANY SHOWERS/THUNDERSTORMS FOR THE REMAINDER OF THE TAF PERIOD. WHILE
THERE IS A SLIGHT CHANCE OF SEEING A SHOWER IN THE EAST LATER
TONIGHT...OPTED TO KEEP ALL TAFS DRY THROUGH THE FORECAST PERIOD.
WITH THE LOSS OF DAYTIME HEATING...THE CU FIELD DIMINISHED. CLEARING
AND LIGHT WINDS ARE EXPECTED AT TAF SITES OVERNIGHT AND THIS WILL
BRING THE POSSIBILITY OF MVFR VSBYS IN FOG FROM 19/09Z TO 19/13Z.
KLUK AND KILN MAY DEVELOP IFR VSBYS IN FOG BUT NOT CONFIDENT
ENOUGH TO INCLUDE IN FORECAST AT THIS TIME.
VFR CONDITIONS EXPECTED AFTER 19/13Z WITH SCATTERED CU DEVELOPING.
OUTLOOK...NO SIGNIFICANT WEATHER EXPECTED.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...BINAU
NEAR TERM...BINAU
SHORT TERM...BINAU
LONG TERM...HICKMAN
AVIATION...PARKER
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1140 PM EDT SUN AUG 18 2013
.SYNOPSIS...
A WEAK DISTURBANCE WILL PASS ACROSS PA ON MONDAY...BRINGING CLOUDS
AND SOME RAIN. HIGH PRESSURE CENTERED NEAR BERMUDA WILL CONTROL
THE WEATHER ACROSS PA DURING MIDWEEK...DELIVERING WARMER AND MORE
HUMID CONDITIONS BEFORE A COLD FRONT ARRIVES AROUND FRIDAY.
&&
.NEAR TERM /UNTIL 8 AM MONDAY MORNING/...
VERY LIGHT RAIN OVER WRN PA IS JUST NOT HOLDING TOGETHER DUE TO
LACK OF SFC FEATURE TO CONCENTRATE/FOCUS LIFT. WIDESPREAD LIFT
ALOFT WILL CONTINUE TO MAKE SOME LIGHT RAIN AND IT SHOULD SPREAD
SLOWLY TO THE EAST AS THE UPPER TROUGH OPENS UP AND SLIDES EAST.
&&
.SHORT TERM /8 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
SLOW MOVING UPPER TROF WILL TAP 1.5" PW FOR MORE WIDESPREAD CHC
OF SHOWERS AND TSTORMS ACROSS MOST AREAS ON MONDAY. INCREASED POPS
SUBSTANTIALLY FOR THE DAYTIME HOURS...DESPITE ONLY WEAK BOUNDARY
LAYER FORCING. GIVEN CLOUD COVER...CAPES WILL BE LIMITED... SO
SEVERE WEATHER IS NOT EXPECTED. HIGHS WILL BE MILDER THAN TODAY
WITH TEMPS REACHING THE MID 70S NORTH TO THE LOWER 80S SOUTH.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
INTERESTING LOW OFF NORFOLK VA THIS AFT...STARTING TO PULL AREA
OF SHOWERS EAST OF THE AREA THIS AFT...BUT MORE SHOWERS ACROSS
THE OH VLY WITH THE UPPER LVL LOW.
EXPECT SHOWERS TO LINGER INTO MONDAY...BEFORE CONDITIONS IMPROVE
LATE. AFTER THIS...MAINLY DRY EXPECT FOR LATER THU INTO FRIDAY...
WHEN A COLD FRONT MOVES ACROSS PA. SOME RISK OF SHOWERS ON WED
ACROSS THE SE LIKE TODAY...BUT LEFT OUT FOR NOW. OVERALL A
COMPLEX PATTERN...WITH THE TENDENCY FOR MORE STABLE AND LESS
HUMID AIR TO TRY TO BUILD SOUTHWARD EAST OF THE MOUNTAINS...
GIVEN HIGH OVER EASTERN CANADA AND NEW ENGLAND THIS WEEK. AT
THE SAME TIME...WARMER AND MORE HUMID AIR WORKS NORTHWARD
WEST OF THE MOUNTAINS. FOR NOW...LEFT MAX TEMPS CLOSE TO WHAT
WAS IN THE GRIDS. REAL STRONG WARM ADVECTION WITH STRONG
WESTERLY FLOW WILL BE WELL NORTH OF THE US...CANADIAN BORDER
FROM LATE TUE INTO EARLY THU.
MAIN CHANGE WAS TO UP MIN TEMPS MONDAY NIGHT AND TUE NIGHT...GIVEN
GUIDANCE AND OTHER OFFICES.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
VERY SUBTLE FEATURES DRIVING THE FORECAST FOR THE NEXT 24
HOURS...AND THEREFORE FORECAST IS OF SOMEWHAT LOWER CONFIDENCE.
VERY LITTLE PRECIPITATION REMAINS ON RADAR...AS WESTERN PA
ACTIVITY HAS DWINDLED TO JUST A FEW SCATTERED SHOWERS. SHORT RANGE
MODELS CONTINUE TO SUPPORT THE IDEA OF SHOWERS REDEVELOPING
OVERNIGHT ACROSS THE WEST...AND SPREADING INTO CENTRAL PA BY
MORNING. RUC ALSO CONTINUES THE THINKING OF DEVELOPING SCATTERED
CONVECTION ACROSS CENTRAL AREAS TOMORROW AFTERNOON...PROPAGATING
TO THE SOUTH AND EAST.
HOWEVER...BASED ON RADAR TRENDS...HAVE CUT BACK ON PRECIPITATION
IN MOST TAFS OVERNIGHT. FOG AND LOWER STRATUS FORECAST BY MODELS
ALSO SLOWER THAN EXPECTED IN PREVIOUS FORECAST...WITH ALL
LOCATIONS AT 03Z STILL VFR. WILL CONTINUE THE THINKING ALONG THE
LINES OF LOWER CLOUDS AND FOG FORMATION...BUT HAVE BACKED OFF A
BIT ON LOWER LIMITS OF RESTRICTIONS.
UPPER TROF AXIS LIFTS NORTHEAST MONDAY. RESULT WILL BE SLIGHT
SURFACE RIDGING DEVELOPING DURING THE DAY AND A SUBTLE/GRADUAL
WIND SHIFT TO THE WEST DURING THE AFTERNOON. HOWEVER...REMNANTS OF
UPPER TROF MOVING THROUGH THE REGION COULD DEVELOP SOME CONVECTION.
WITHOUT A REAL PUSH OF DRIER AIR...EXPECT MORE FOG FORMATION
MONDAY NIGHT INTO TUESDAY...BEFORE A RETURN TO VFR BY MID WEEK.
OUTLOOK...
MON...AM MVFR/IFR...WITH IMPROVEMENTS DURING THE AFTERNOON MOST
LOCATIONS. ADDITIONALLY...SCATTERED SHOWERS AND ISOLATED TSRA.
TUE...AM FOG POSS. THEN MAINLY VFR.
WED-THU...VFR.
FRI...MVFR WITH SCT SHRA/TSRA.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...DANGELO
SHORT TERM...DEVOIR
LONG TERM...MARTIN
AVIATION...JUNG
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1237 PM CDT SAT AUG 17 2013
.UPDATE...FOR 18Z AVIATION.
&&
.AVIATION...18Z TAF DISCUSSION.
A WEAK INVERTED TROUGH IS PROVIDING DECENT LOW LEVEL MOISTURE
TRANSPORT INTO THE STATE TODAY. THIS MEANS MOSTLY CLOUDY SKIES
WILL CONTINUE FOR MOST OF...IF NOT ALL...OF THIS PERIOD. IN
ADDITION...THERE SHOULD BE JUST ENOUGH HEATING TO HELP SPARK A FEW
SHOWERS THIS AFTERNOON. THE MAJORITY OF THIS ACTIVITY SHOULD
REMAIN ALONG AND WEST OF INTERSTATE 65 AS AN UPPER LEVEL LOW
CENTERED OVER THE MISSISSIPPI RIVER WILL BE THE PROVIDER OF THE
LIFT. LATER TONIGHT...WIDESPREAD SHOWERS ARE EXPECTED TO START
MOVING INTO THE EASTERN HALF OF THE STATE FROM THE SOUTHEAST. WILL
GO AHEAD AND PREVAIL NOT ONLY THIS RAIN...BUT ASSOCIATED FLIGHT
CATEGORY DEGRADATION STARTING BY 03Z THIS EVENING AT KCSV.
KCKV/KBNA WILL ALSO SEE REDUCED FLIGHT CATEGORIES...WITH SOME LIFR
POSSIBLE AROUND DAYBREAK AT KCKV. WINDS WILL REMAIN LIGHT...MAINLY
OUT OF THE SOUTHEAST.
UNGER
&&
.PREV DISCUSSION... /ISSUED 905 AM CDT SAT AUG 17 2013/
UPDATE...
EARLIER SHOWER AND TSTM ACTIVITY HAS LIFTED OFF TO THE NORTH. A
BAND OF VERY LIGHT SHOWER ACTIVITY APPEARS TO BE WORKING NORTHWARD
ACROSS CENTRAL AREAS. OVERALL HOWEVER...MODELS ARE ZONING IN ON A
PERIOD OF SUBSIDENCE THROUGH THE MORNING HOURS. HOWEVER...BY
AFTERNOON SUBSIDENCE WILL BEGIN TO GIVE WAY TO A SLIGHTLY UPWARD
OMEGA FIELD AND THUS...SHOULD STILL SEE CONVECTIVE ACTIVITY
INCREASE. HRRR IN SUPPORT OF REDEVELOPMENT AS WELL.
FOR THE GRID UPDATE...WILL TWEAK POPS DOWN FOR THE PRE 18Z PERIOD.
OTW...LITTLE ADJUSTMENTS NEEDED. MOSTLY CLOUDY SKIES SHOULD
PREVAIL AND THUS THE EXPECTED HIGH TEMPS IN THE LOWER 80S STILL
LOOKS REASONABLE.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
27
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
905 AM CDT SAT AUG 17 2013
.UPDATE...
EARLIER SHOWER AND TSTM ACTIVITY HAS LIFTED OFF TO THE NORTH. A
BAND OF VERY LIGHT SHOWER ACTIVITY APPEARS TO BE WORKING NORTHWARD
ACROSS CENTRAL AREAS. OVERALL HOWEVER...MODELS ARE ZONING IN ON A
PERIOD OF SUBSIDENCE THROUGH THE MORNING HOURS. HOWEVER...BY
AFTERNOON SUBSIDENCE WILL BEGIN TO GIVE WAY TO A SLIGHTLY UPWARD
OMEGA FIELD AND THUS...SHOULD STILL SEE CONVECTIVE ACTIVITY
INCREASE. HRRR IN SUPPORT OF REDEVELOPMENT AS WELL.
FOR THE GRID UPDATE...WILL TWEAK POPS DOWN FOR THE PRE 18Z PERIOD.
OTW...LITTLE ADJUSTMENTS NEEDED. MOSTLY CLOUDY SKIES SHOULD
PREVAIL AND THUS THE EXPECTED HIGH TEMPS IN THE LOWER 80S STILL
LOOKS REASONABLE.
&&
.PREV DISCUSSION... /ISSUED 649 AM CDT SAT AUG 17 2013/
UPDATE...FOR 12Z AVIATION FORECASTS.
AVIATION...CKV AND BNA RECEIVED LOCALLY HEAVY RAINFALL LAST NIGHT
AND MAY SEE A BRIEF PERIOD OF SOME RAG TAG IFR OR MVFR CIGS EARLY
THIS MORNING. OTHERWISE, EXPECT VFR CIGS THROUGHOUT THE TAF
PERIOD.
SOME BRIEF VIS RESTRICTIONS ARE LIKELY WITH ANY SHRA OR ISOLATED
TSRA THAT MIGHT PASS OVER A MID STATE TERMINAL.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
21
AREA FORECAST DISCUSSION
NWS MIDLAND/ODESSA TX
1222 AM CDT Sat Aug 17 2013
.DISCUSSION...
See Aviation Discussion below.
&&
.AVIATION...
VFR conditions will prevail next 24 hours. Latest radar loop shows
convection N of KHOB diminishing, and remnants look to pass NE of
the terminal. Otherwise, another widespread CU field is expected
to develop today 16-19Z, w/bases 7-8 kft agl.
&&
.PREV DISCUSSION... /ISSUED 633 PM CDT Fri Aug 16 2013/
AVIATION...
00Z TAF issuance...
No major aviation concerns for the next 24...VFR conditions are
expected at all TAF sites. There is currently come thunderstorm
activity just west of CNM this evening but NM terminals do not look
to be affected in the immediate future. Will need to keep an eye on
any convection moving south out of Chaves county and send an update
to include mention of TSRA if needed. Generally light east
southeasterly winds this evening should persist overnight and into
Saturday.
PREV DISCUSSION... /ISSUED 154 PM CDT Fri Aug 16 2013/
DISCUSSION...
The Mesoscale Convective Complex which clipped the western Low
Rolling Plains this morning generated quite the bubble surface high
and sent an outflow boundary westward across the CWA. The modified
airmass behind this boundary will result in high temperatures
several degrees lower than what was previously expected, especially
over the eastern half of the forecast area, and will affect
convection this afternoon, and more than likely, tonight. The
latest RUC bears this out with a higher theta e axis at H7 shunted
west of the 16/12Z operational models. Think we will still see
widely scattered thunderstorms over the higher terrain through max
heating, but think convection will drop into southeast New Mexico
along the theta e axis overnight. Instability around 1000 J/Kg, mid
level lapse rates of 7.5-8 C/Km and 0-6 Km Bulk Shear Vectors around
35kt could yield a few strong to severe storms. Since the overall
threat is limited, will make a mention in the HWO.
Think convection Saturday and Sunday will mainly occur over the
higher terrain as an upper ridge over Arizona repositions further
north over the Four Corners region, with the flow aloft over the CWA
becoming more northeasterly. Storms will likely develop over the
higher terrain of New Mexico each afternoon, then spread south/
southwestward under the eastern fringe of the upper ridge.
Temperatures will stay near to above normal through the weekend.
Models are still undecided on whether an inverted upper trough will
trek westward into the area from the Gulf of Mexico next week. Will
not add any rain chances at this time, but some could be added mid
to late next week for such a feature if the upper ridge does not
remain too strong for it to impinge upon the area. Temperatures
should be near normal next week, especially the second half.
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...NONE.
TX...NONE.
&&
$$
44
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1140 PM CDT FRI AUG 16 2013
.DISCUSSION...
See aviation discussion below.
&&
.AVIATION...
VFR will prevail the next 24 hours with light winds through the
period.
&&
.PREV DISCUSSION... /ISSUED 723 PM CDT FRI AUG 16 2013/
DISCUSSION...
Expect VFR conditions to prevail over west central Texas through the
next 24 hours.
AVIATION...
Early morning convection has stabilized the atmosphere today.
Soundings do hint at the possibility of FEW150 during the overnight
hours, but given the lack of any evidence of this upstream on
satellite imagery, will opt to maintain SKC at all terminals. Winds
are expected to become light and variable overnight.
PREV DISCUSSION... /ISSUED 336 PM CDT FRI AUG 16 2013/
SHORT TERM...
/Tonight and Tomorrow/
Visible satellite imagery shows sunny skies across West Central
Texas this afternoon. The latest mesoanalysis indicates a stable
environment over our area, with an instability axis across South and
far West Texas.
The models, including the 3KM HRRR model develop scattered
thunderstorms over Eastern New Mexico and far West Texas in the
instability axis during the late afternoon and evening. Upper level
northerly flow will keep this activity west of our area for tonight.
Lows will be in the mid 60s to lower 70s.
Going with a dry forecast for Saturday across the area. Isolated
thunderstorms will probably fire to our west during the afternoon
hours. The upper level northerly flow should keep the storms west of
our area. Highs will be in the lower to mid 90s.
LONG TERM...
/Saturday Night through Friday/
The upper level flow will be north to northeast next week as a high
pressure ridge sets up from the Southern Rockies into the Central
Plains. Basically a normal summertime pattern with little upper
level and mesoscale forcing. Temperatures will be near or slightly
above seasonable normals. Highs will be in the 90s with lows in the
upper 60s to lower 70s. Going with a dry forecast through the
extended period.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 66 92 67 94 68 / 10 10 5 5 5
San Angelo 67 93 68 95 68 / 10 10 5 5 5
Junction 68 94 69 97 66 / 10 10 5 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
24
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
247 PM EDT SAT AUG 17 2013
.SYNOPSIS...
A RIDGE OF HIGH PRESSURE WILL REMAIN SITUATED ALONG THE LEE OF THE
CENTRAL APPALACHIANS. AN AREA OF LOW PRESSURE WILL PROGRESS
NORTHEAST ALONG THE STALLED FRONTAL BOUNDARY THAT EXTENDED FROM
GEORGIA TO THE COAST OF THE CAROLINAS. AN ACTIVE WEATHER PATTERN
WILL CONTINUE INTO THE EARLY PART OF NEXT WEEK AS A TROUGH OF LOW
PRESSURE APPROACHES THE REGION FROM THE WEST.
&&
.NEAR TERM /THROUGH SUNDAY/...
AS OF 230 PM EDT SATURDAY...
EARLY THIS AFTERNOON...AREAS OF RAIN WERE EXPANDING IN COVERAGE IN
RESPONSE TO THE NEXT UPPER LEVEL WAVE APPROACHING IN THE UPPER LEVEL
SOUTHWEST FLOW. MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT THAT
ISENTROPIC LIFT ON THE 305K SFC SIGNIFICANTLY INCREASES BETWEEN NOW
AND EARLY TONIGHT. AS A RESULT...HAVE RAMPED UP POPS THROUGH THE
EVENING HOURS...WITH PRECIPITATION ARRIVING LAST IN THE GREENBRIER
VALLEY.
WITH ABUNDANT CLOUDS AND WIDESPREAD PRECIP...EXPECT A SMALL DROP IN
TEMPS TONIGHT AND GENERALLY WENT ABV GUIDANCE FOR LOWS.
ON SUNDAY...WE BEGIN TO BECOME UNDER THE INFLUENCE OF THE WEAKENING
UPPER LEVEL WAVE IN THE OHIO VALLEY. THE 850-700MB FLOW VEERS TO THE
WEST WHICH REDUCES THE MOISTURE DEPTH. HOWEVER...WITH A SHALLOW
WEDGE STILL EXPECTED TO BE IN PLACE...AREAS OF DRIZZLE/LIGHT RAIN
WILL CONTINUE SUNDAY. A FEW BREAKS IN THE CLOUDS MAY BE SEEN IN THE
FAR SOUTHWEST AND THE FAR SOUTHERN PORTION OF THE FORECAST
AREA...BUT ONLY A SMALL RISE IN TEMPS IS ANTICIPATED AND WENT BELOW
GUIDANCE AT MOST LOCATIONS FOR HIGHS SUNDAY.
FORECAST HIGHS ARE A FEW DEGREES ABOVE THE RECORD MINIMUM HIGH TEMPS
FOR AUGUST 18TH (SEE CLIMATE SECTION)
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM EDT SATURDAY...
THE UPPER TROUGH THAT HAS BEEN LINGERING OVER THE MID-MISSISSIPPI
VALLEY WILL MAKE GRADUAL PROGRESSION EASTWARD DURING THIS PART OF
THE FORECAST. AS IT DOES...THE FLOW AND THE AIRMASS IN ADVANCE OF IT
WILL HAVE PLENTIFUL GULF OF MEXICO MOISTURE AND LINGERING OUTFLOW
BOUNDARIES FROM PRIOR CONVECTION. THE RESULT IS EXPECTED TO BE
SCATTERED SHOWERS AND A FEW THUNDERSTORMS THROUGH AT LEAST MONDAY.
ON TUESDAY...WE WILL NOT HAVE A DRY FORECAST...BUT ONE THAT IS
STARTING TO TREND TOWARDS LESS COVERAGE OF SHOWERS AND STORMS. A
WEAKENING OF THE UPPER TROUGH AND TRANSITION TO A MORE ZONAL FLOW IS
TO BLAME. TEMPERATURES WILL ALSO START TO MODERATE A BIT DURING THIS
TIME PERIOD.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 1245 PM EDT SATURDAY...
DURING THIS PORTION OF THE FORECAST...MODEL GUIDANCE TRANSITIONS
FROM A NEAR ZONAL FLOW ACROSS THE AREA...TO ONE THAT HAS SOME DEGREE
OF A NORTHWEST FLOW ORIENTATION. THIS COMES WITH DIFFERENCES IN THE
POSITION OF A BUILDING UPPER HIGH/RIDGE. THE GFS SOLUTION IS FARTHER
WEST WITH THE HIGH...KS/MO...AND AS SUCH HAS A STEEPER ANGLE OF THE
NORTHWEST FLOW OVER THE REGION...AND A BETTER SHOT FOR UPSTREAM
DISTURBANCES TO HEAD INTO OR NEAR THE REGION. THE ECWMF OFFERS A
SOLUTION WITH THE CENTER OF THE UPPER HIGH OVER THE LOWER OHIO
VALLEY...WITH STEEPER NORTHWEST FLOW ON ITS EASTERN SIDE MORE OVER
NY/PA THAN OVER OUR REGION. THE OPERATIONAL GFS SOLUTION OFFERS A
COOLER AND POTENTIALLY WETTER SOLUTION AS COMPARED TO THE
OPERATIONAL ECMWF.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
AS OF 120 PM EDT SATURDAY...
RATHER CHAOTIC PATTERN IN THE SHORT TERM. SHALLOW WEDGE IN PLACE
ALONG THE ERN SEABOARD AS PIECES OF ENERGY MOVE OVER THE AREA IN
SWLY FLOW AHEAD OF CLOSED LOW OVER THE MID MISSISSIPPI VALLEY. MODEL
PCPN FIELDS HAVE BEEN OVERDONE WITH THIS SYSTEM AND CURRENTLY ONLY
SEEING PATCHY LIGHT PCPN NEAR KDAN. WITH SUCH A DIFFUSE PATTERN WILL
NOT TRY TO GET FANCY WITH TIMING OF ELEMENTS BUT LIKING THE LATEST
GFS AND HRRR RUNS FOR OVERALL TRENDS.
EXPECTING PCPN TO BE ON THE INCREASE FROM THE SOUTHWEST...MAINLY FROM
00Z ON THOUGH IT LOOKS TO TAKE A BIT LONGER TO WORK INTO KLWB. AS PCPN
GETS GOING CIGS AND VSBYS WILL BE COMING DOWN OVERNIGHT.
EXPECTING IFR TO DEVELOP AFTER ABOUT 06ZAT ALL LOCATIONS...BUT
MAINLY DUE TO CIGS AT KDAN...KLYH...AND KROA. LOOKS LIKE PCPN WILL
BE TAPERING OFF TOWARD 12Z AS SFC LOW ALONG THE COAST STARTS TO
PULL OFF TO THE NORTHEAST. NOT EXPECTING SIGNIFICANT WINDS THROUGH
THE TAF PERIOD.
AVIATION EXTENDED...
WEATHER WILL REMAIN UNSETTLED THROUGH THE START OF NEXT WEEK AS
AFOREMENTIONED CLOSED LOW OPENS UP AND LIFTS OUT...ALLOWING FOR
SOME FLAT RIDGING BY MIDWEEK. HOWEVER...EASTERN TROF WANTS TO
REDEVELOP TOWARD THE END OF THE WEEK WHICH BRINGS UNSETTLED
CONDITIONS BACK TO THE AREA. EXPECT SOME LOW CIGS/VSBYS WITH
NOCTURNAL FOG AND SOME DIURNAL CONVECTIVE PCPN THROUGH THE
PERIOD...WITH TUESDAY AND WEDNESDAY LOOKING MOST FAVORABLE FOR
AVIATORS.
&&
.CLIMATE...
AS OF 240 PM EDT SATURDAY...
RECORD MINIMUM HIGH TEMPERATURES FOR AUGUST 18.
CITY........RECORD/YEAR
BLUEFIELD WV....70/1981
DANVILLE VA.....70/1992
LYNCHBURG VA....65/1957
BLACKSBURG VA...69/1992
ROANOKE VA......65/1957
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...DS
NEAR TERM...PH
SHORT TERM...DS
LONG TERM...DS
AVIATION...MBS
CLIMATE...PH
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
125 PM EDT SAT AUG 17 2013
.SYNOPSIS...
HIGH PRESSURE ALONG THE MID ATLANTIC COAST WILL REMAIN WEDGED
ALONG THE EASTERN SLOPES OF THE APPALACHIANS THROUGH THIS
EVENING...MAINTAINING AN EASTERLY WIND ACROSS THE AREA. SEVERAL
DISTURBANCES PASSING ALONG A STALLED FRONTAL BOUNDARY TO OUR
SOUTH AND EAST WILL BRING PERIODS OF RAIN TO THE AREA THROUGH
THE WEEKEND. SCATTERED SHOWERS MAY PERSIST EARLY NEXT WEEK AS A
TROUGH OF LOW PRESSURE MOVES EASTWARD FROM THE OHIO VALLEY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 935 AM EDT SATURDAY...
DRY AIR CONTINUES TO HOLD IN PLACE...ESPECIALLY ACROSS THE
MOUNTAINS WITH DEWPOINTS STILL IN THE LOW TO MID 50S. THE 12Z RNK
SOUNDING INDICATED A LARGE AREA OF DRY AIR...ESPECIALLY BELOW
700MB. IN THE UPPER LEVELS OF THE ATMOSHPERE...WATER VAPOR
SATELLITE IMAGERY HINTS AT A WEAK WAVE EMBEDDED EMBEDDED IN THE
SOUTHWEST FLOW MOVING ACROSS EASTERN NC HELPING TO GENERATE LIGHT
RAIN SOUTH OF LYH INTO THE VA SOUTHSIDE AND NORTHERN NC PIEDMONT.
THE BLENDED TOTAL PRECIP WATER IMAGE SHOWS HIGHEST PWAT AIR
REMAINS IN THE FAR SOUTHEAST PORTION OF THE FORECAST AREA THIS
MORNING.
AS THE WEAK WAVE IN NC DRIFTS NORTHEAST THIS AFTERNOON...LIGHT
PRECIP OCCURRING THIS MORNING SHOULD WANE BY MIDDAY. SHOWERS MAY
RE-DEVEVLOP EARLY THIS AFTERNOON UNDER AXIS OF HIGHER PWAT AIR IN
THE EAST...BUT FOR THE MOUNTAINS...PRECIP MAY NOT ARRIVE UNTIL
THIS EVENING/TONIGHT WHEN THE NEXT UPPER LEVEL SHORTWAVE
APPROACHES FROM THE SOUTHWEST.
AS A RESULT...PUSHED UP HIGH TEMPS IN THE MOUNTAINS WHERE CLOUDS
WILL BE SLOWER TO ARRIVE AND DELAYED THE ARRIVAL OF PRECIP. IN THE
EAST...LITTLE CHANGES WERE MADE TO THE FORECAST...BUT DID INCREASE
HIGHS AT LYH WHERE READINGS ARE ALREADY A FEW DEGREES ABV THE
FORECAST.
SHOULD BE UNDER DEEPER MOISTURE TONIGHT WITH A COMBO OF THE
UPPER SYSTEM HEADING INTO THE WEST AND BETTER ONSHORE FLOW OUT
EAST WITH THE SURFACE WAVE. ALSO BETTER DIFFLUENCE ALOFT AHEAD OF
A SPEED MAX PASSING PASSING JUST WEST SHOULD COINCIDE WITH THE
LINGERING THETA-E GRADIENT TO SUPPORT MORE WIDESPREAD -RA AND
PERHAPS SOME ELEVATED HEAVIER SHRA OVER THE COOL POOL. THUS
MOSTLY LIKELY/CAT POPS OVERALL. ONLY SMALL DIURNAL TEMP CHANGES
UNDER THE CLOUD CANOPY/-RA WITH LOWS UPPER 50S/LOW 60S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 332 AM EDT SATURDAY...
AN UPPER LEVEL BLOCKING RIDGE IN THE WESTERN ATLANTIC IS
EXPECTED TO JOG TO THE SOUTHWEST ON SUNDAY. THIS WILL ALLOW A
COASTAL LOW TO TRACK NORTHEAST ALONG THE MID ATLANTIC COAST.
MOISTURE ACROSS THE REGION SHOULD BECOME SHALLOWER AS THE FOCUS
WILL BE WITH THE DEPARTING SURFACE LOW. DESPITE THE REDUCTION IN
MOISTURE...GRAY/DAMP CONDITIONS WILL REMAIN AS THE SURFACE WEDGE
WILL STILL BE IN PLACE SUNDAY MORNING. WITH THE BLOCKING HIGH
JOGGING TO THE SOUTHWEST...THE CLOSED LOW OVER THE MID MISSISSIPPI
VALLEY WILL OPEN INTO A TROUGH WHILE TRACKING TO THE OHIO VALLEY
SUNDAY. PRESSURE FALLS OVER THE OHIO VALLEY AND WARM AIR ADVECTION
FROM THE SOUTHWEST WILL ERODE THE WEDGE THROUGH THE DAY SUNDAY.
RAIN AND DRIZZLE WILL THEN GET REPLACED BY SCATTERED SHOWERS AS
THE UPPER LEVEL TROUGH AND ASSOCIATED SHORT WAVES APPROACH THE
REGION SUNDAY AFTERNOON AND CROSS OVER THE AREA SUNDAY NIGHT. THE
TROUGH AXIS IS OVERHEAD ON MONDAY TO KEEP SCATTERED SHOWERS AND
THUNDERSTORMS IN THE FORECAST...BUT THE FOCUS OF AREAL COVERAGE
WILL BE ALONG THE COAST.
AS WITH ALL ERODING WEDGES...TEMPERATURES WILL BE TRICKY TO
FORECAST. AREAS BREAKING OUT OF THE WEDGE SHOULD SEE TEMPERATURES
JUMP INTO THE MID TO UPPER 70S DURING THE AFTERNOON. AREAS
REMAINING IN THE WEDGE MAY STAY IN THE 60S. LOOKING AT THE LIFTED
INDEX AND LOW LEVEL FLOW...THE NAM KEEPS THE WEDGE OVER RNK
NORTHEAST CORNER DEEP INTO SUNDAY NIGHT. THE GFS HAS THE WEDGE
CLEARING THE PIEDMONT SOMETIME SUNDAY EVENING. IF THIS IS THE
CASE...THE CITY OF LYNCHBURG AND THE CENTRAL PIEDMONT OF VIRGINIA
MAY AGAIN HAVE TEMPERATURES 20F COOLER THAN NORMAL. THE WEDGE WILL
BE GONE MONDAY AND TEMPERATURES WILL APPROACH NORMAL BY THE
AFTERNOON.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 330 PM EDT FRIDAY...
A GENERAL WEAKNESS...IN AN OTHERWISE STAGNANT...UPPER LEVEL FLOW
WILL COVER THE EASTERN U.S. THROUGH MOST OF THE LONG TERM PERIOD.
THE 00Z ECMWF AND CANADIAN MODELS DEPICT AN UPPER LEVEL LOW ACROSS
THE OHIO VALLEY...THEN DRIFTING SOUTHEAST THROUGH THE PERIOD. THE
12Z GFS IS NOW COMING AROUND TO THIS SOLUTION WHICH WOULD RESULT IN
A MORE UNSETTLED PERIOD.
WITH PWATS FORECAST TO REMAIN AROUND 1.5 INCHES AND WEAK LOW LEVEL
SOUTH OR SOUTHEAST FLOW IN PLACE...WOULD EXPECT A TYPICAL SUMMER
PATTERN OF DAILY (MAINLY DIURNALLY DRIVEN) SHOWERS AND STORMS DRIVEN
BY LOCALIZED AREAS OF LOW LEVEL CONVERGENCE EACH DAY.
TEMPERATURES THROUGH THE PERIOD SHOULD BE NEAR NORMAL TO SLIGHTLY
ABOVE NORMAL...ESPECIALLY LATE IN THE PERIOD WITH GEFS SHOWS 850MB
TEMPS RISING 1-2 STANDARD DEVIATIONS ABV NORMAL.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 120 PM EDT SATURDAY...
RATHER CHAOTIC PATTERN IN THE SHORT TERM. SHALLOW WEDGE IN PLACE
ALONG THE ERN SEABOARD AS PIECES OF ENERGY MOVE OEVR THE AREA IN
SWLY FLOW AHEAD OF CLOSED LOW OVER THE MID MISSISSIPPI VALLEY. MODEL
PCPN FIELDS HAVE BEEN OVERDONE WITH THIS SYSTEM AND CURRENTLY ONLY
SEEING PATCHY LIGHT PCPN NEAR KDAN. WITH SUCH A DIFFUSE PATTERN WILL
NOT TRY TO GET FANCY WITH TIMING OF ELEMENTS BUT LIKING THE LATEST
GFS AND HRRR RUNS FOR OVERALL TRENDS.
EXPECTING PCPN TO BE ON THE INCREASE FROM THE SOUTHWEST...MAINLY FROM
00Z ON THOUGH IT LOOKS TO TAKE A BIT LONGER TO WORK INTO KLWB. AS PCPN
GETS GOING CIGSAND VSBYS WILL BE COMING DOWN OVERNIGHT. EXPECTING IFR
TO DEVELOP AFTER ABOUT 06ZAT ALL LOCATIONS...BUT MAINLY DUE TO CIGS AT
KDAN...KLYH...AND KROA. LOOKS LIKE PCPN WILL BE TAPERING OFF TOWARD 12Z
AS SFC LOW ALONG THE COAST STARTS TO PULL OFF TO THE NORTHEAST. NOT
EXPECTING SIGNIFICANT WINDS THROUGH THE TAF PERIOD.
...AVIATION EXTENDED...
WEATHER WILL REMAIN UNSETTLED THROUGH THE START OF NEXT WEEK AS
AFOREMENTIONEDCLOSED LOW OPENS UP AND LIFTS OUT...ALLOWING FOR SOME
FLAT RIDGING BY MIDWEEK. HOWEVER...EASTERN TROF WANTS TO REDEVELOP
TOWARD THE END OF THE WEEK WHICH BRINGS UNSETTLED CONDITIONS BACK TO
THE AREA. EXPECT SOME LOW CIGS/VSBYS WITH NOCTURNAL FOG AND SOME DIURNAL
CONVECTIVE PCPN THROUGH THE PERIOD...WITH TUESDAY AND WEDNESDAY LOOKING
MOST FAVORABLE FOR AVIATORS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/NF
NEAR TERM...JH/PH
SHORT TERM...RCS
LONG TERM...PH
AVIATION...MBS
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1202 AM EDT SAT AUG 17 2013
.SYNOPSIS...
LOW PRESSURE WILL SLOWLY MOVE NORTHEAST ALONG THE MID ATLANTIC
COAST THIS WEEKEND. HIGH PRESSURE RETURNS EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
WILL BE MAKING SIGNIFICANT CHANGES TO THE GRIDS THROUGH 00Z SUN
WITH THE 1 AM UPDATE. MAIN CHANGE WILL TO LWR RAIN CHANCES ACROSS
THE NRN HALF OF FA AND LIMITING IT TO SAT AFTRN. IT MAY NOT RAIN
AT ALL ACROSS THE LW MD ERN SHORE UNTIL SAT EVE. RAIN CHANCES
SLOWLY INCRS THROUGH THE DAY ACROSS THE SOUTH. THIS ALL BASED ON
LATEST DATA WHERE THE MODELS ARE SHOWING DRYER AIR FROM THE HIGH
PRS OVR THE AREA WINNING OUT ACROSS THE FA THRU AT LEAST 18Z.
PVS DSCN:
UPDATE AS OF 1045 PM EDT...ANOTHER STRANGE EVENING WHERE WX
HAS BEEN TRENDING DRIER THAN EXPECTED. A BAND OF CLOUDS IS
CURRENTLY MOVING OFF THE COAST AND A BATCH OF RAIN HAS DEVELOPED
OVER THE VA TIDEWATER AND NE NC. WILL CONTINUE TO CARRY LIKELY
POPS IN THIS AREA THRU EARLY AM AS PCPN EXITS.
ELSEWHERE...CLEARING HAS WORKED INTO CENTRAL VA AND WILL CONTINUE
TO ADVANCE EAST THRU EARLY AM. THIS CLEARING HAS ALLOWED TEMPS TO
FALL A LITTLE LOWER THAN EXPECTED AND THUS HAVE LOWERED OVN LOWS A
FEW DEGREES. LOWS IN THE UPR 50S NW TO THE MID 60S SE. THERE IS
SOME INDICATION IN THE LATEST IR SATELLITE IMAGERY AND SFC OBS
THAT CLOUDS MOVING NORTHWARD THRU CENTRAL NC WILL SPREAD OVER OUR
AREA DURING THE PRE-DAWN HOURS SO WILL HAVE CLOUDS RETURNING
OVERNIGHT. HOWEVER..QUESTIONS REMAIN AS TO JUST HOW MUCH PCPN WILL
PUSH NORTHWARD BY DAYBREAK. LATEST NAM AND HRRR ARE NOT THAT
EXCITED ABOUT RAIN GETTING NORTH OF THE HWY 58 IN SOUTHERN VA TIL
AFTER 15Z SAT...SO NEXT SHIFT WILL LIKELY BE TRIMMING POPS BACK
EVEN FARTHER FOR SAT MORN.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
UPPER LEVEL HIGH PRESSURE OVER THE CTRL ATLANTIC SHIFTS TWD THE SE
COAST OVER THE WEEKEND. MEANWHILE...AN UPPER TROUGH WILL STAY WELL
ROOTED IN THE OH/TN VALLEYS DUE TO AN AMPLIFYING RIDGE OVER THE
GREAT BASIN. THE COMBINATION OF THESE UPPER LEVEL FEATURES WITH
THE STALLED SFC BOUNDARY ALONG THE CAROLINA COAST WILL CAUSE
MOISTURE AND SHORTWAVE ENERGY TO STREAM ACROSS THE MID ATLANTIC
REGION SATURDAY THROUGH SUNDAY NIGHT. A CONTINUATION OF FAVORABLE
ISENTROPIC LIFT MOVING INTO THE AREA FROM THE SOUTHWEST ON
SATURDAY WILL QUICKLY SATURATE THE LOWER ATMOSPHERE AND ACT TO
ENHANCE STEADY PRECIPITATION/RAINFALL. PWATS WILL GRADUALLY
INCREASE THROUGH THE WEEKEND FROM ROUGHLY 0.75 INCHES NORTH TO
1.50 INCHES SOUTH FOR TONIGHT...TO AROUND 2.00 INCHES NORTH TO
2.35 INCHES SOUTH BY SUNDAY. THE BEST POTENTIAL FOR WIDESPREAD
STEADY RAIN IS SATURDAY NIGHT. HOWEVER THE WEEKEND WILL NOT BE A
COMPLETE WASHOUT...BUT DO EXPECT PERIODS OF RAIN THAT WILL BE
MODERATE TO HEAVY AT TIMES AND MOSTLY CLOUDY TO CLOUDY SKIES. FOR
SUNDAY...FORECAST MODELS ARE HINTING AT A DRY SLOT MOVING INTO
NE NC AND SE VA DURING THE DAY AS THE ATLANTIC HIGH PUSHES CLOSER
TO THE SOUTHEAST COAST. IF THIS OCCURS...THEN THERE COULD BE A
NICE REPRIEVE FROM THE RATHER WET WEEKEND RAINS IN THE
AFOREMENTIONED AREAS. AT THIS TIME...IT IS DIFFICULT TO PINPOINT
EXACTLY WHERE THE DRIER CONDITIONS MAY SET UP AND HAVE THEREFORE
KEPT A CHANCE OF PRECIP IN THE ONGOING FORECAST FOR SUNDAY
AFTN/EVENING. DUE TO EXTENSIVE CLOUD COVER AND COOLER AMBIENT AIR
DUE TO EVAPORATIVE COOLING PROCESSES...TEMPERATURES WILL BE ON THE
COOL SIDE WITH HIGHS SAT/SUN GENERALLY IN THE 70S (NEAR 80 NE
NC/FAR SE VA ON SUN DUE TO POTENTIAL DRY SLOT/CLEARING). THE LOWS
ON SATURDAY NIGHT WILL GENERALLY BE IN THE 60S (NEAR 70 COASTAL
NE NC/FAR SE VA).
THE OH/TN VALLEY TROUGH AND GREAT BASIN HIGH BOTH BEGIN TO WASH
OUT ON MONDAY AND APPEAR TO RESULT IN A PSEUDO-WESTERLY (OR ZONAL)
FLOW. AT THIS TIME...IT SHOULD BE ENOUGH TO START PUSHING THE
PERSISTENTLY RAINY WX PATTERN OUT OF THE AREA BUT NOT UNTIL
TUESDAY/TUESDAY NIGHT. HIGH TEMPERATURES REBOUND INTO THE LOWER
80S SINCE A COMBINATION OF SUN AND CLOUDS ARE ANTICIPATED DURING
THE DAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
STRONG UPPER-LEVEL WESTERLY FLOW PREVAILS OVER SOUTHERN CANADA
THROUGH THE MIDDLE AND LATER PORTIONS OF NEXT WEEK. UNDERNEATH
THIS ZONAL FLOW...MID-LEVEL ANTICYCLONES WILL REMAIN NEARLY
STATIONARY OVER THE SOUTHERN PLAINS AND WESTERN ATLANTIC. AN AREA
OF (SOMEWHAT) LOWER HEIGHTS IS PROGGED OVER THE APPALACHIAN
PLATEAU. HOWEVER...THE MID ATLANTIC REGION SHOULD LARGELY REMAIN
UNDER THE INFLUENCE OF THE WESTERN ATLANTIC RIDGE. HENCE...
PRECIPITATION POTENTIAL SHOULD BE MINIMAL (NEAR OR BELOW CLIMO)
DUE TO A LACK OF LARGE SCALE FORCING FOR STORM ORGANIZATION...
DESPITE A WARM AND INCREASINGLY HUMID AIRMASS. HIGH TEMPERATURES
SHOULD AVERAGE AROUND SEASONAL NORMALS TUESDAY THROUGH FRIDAY
(MID/UPPER 80S)...WITH A FEW 90 DEGREE HIGHS POSSIBLE IN FAVORED
HOT SPOTS. LOWS SHOULD PRIMARILY RANGE FROM THE UPPER 60S TO LOW 70S.
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
A TROUGH OF LOW PRES ALONG THE MID AND SOUTH ATL COAST CONTINUES
TO MOVE NE AND AWAY FROM LAND...RESULTING IN NE FLOW ACROSS THE
REGION IN THE LOW LEVELS. ALOFT...SWLY FLOW WILL GRADUALLY
INCREASE AND RESULT IN OVERRUNNING MOISTURE THAT WILL GRADUALLY
SPREAD NORTH LIKELY STARTING OVERNIGHT INTO SAT MORNING. EXACT
TIMING OF THE PRECIP WILL BE TRICKY. CIGS AND VSBY WITH THE RAIN
WILL START OUT AS MVFR FOR SOME TIME INITIALLY BUT TRANSITION TO
IFR LATER SATURDAY MORNING AND EARLY AFTERNOON AS A WAVE OF LOW
PRESSURE MOVES ALONG THE COASTAL FRONT. ONCE CONDITIONS BECOME IFR
SATURDAY...THEY WILL LIKELY REMAIN IFR FOR A PERIOD OF TIME WHILE
THE OVERRUNNING CONTINUES INTO THE AFTERNOON.
&&
.MARINE...
THE LATEST MSAS SURFACE ANALYSIS SHOWS A 1017MB LOW ~110NM ENE OF
CAPE HATTERAS TRACKING NE ALONG A COASTAL FRONT ALIGNED PARALLEL
TO THE SOUTHEAST COAST. A NE WIND (STRONGEST OFF THE CURRITUCK
OUTER BANKS) IS GRADUALLY DIMINISHING AS THE LOW PULLS AWAY AND
HIGH PRESSURE RETURNS FROM THE N. ANOTHER LOW (PRESENTLY OVER
SOUTHERN GA) IS PROGGED TO LIFT NE ALONG THE SOUTHEAST COAST
TONIGHT THROUGH SATURDAY...EVENTUALLY REACHING THE MID ATLANTIC
SATURDAY NIGHT AND SUNDAY...BEFORE PULLING TO THE NE SUNDAY NIGHT.
THIS PATTERN WILL MAINTAIN A PERSISTENT NE FLOW OVER THE REGION
THROUGH SATURDAY NIGHT FOR THE ENTIRE AREA...AND INTO SUNDAY FOR
THE NORTHERN PORTION OF THE MARINE AREA. WIND SPEEDS REMAIN CAPPED
AROUND 15KT ALONG WITH SEAS/WAVES CAPPED AT 4FT/3FT. CONFIDENCE ON
SCA HEADLINES REMAINS LOW...SO NO FLAGS WILL BE ISSUED. ALTHOUGH A
FEW BRIEF PERIODS OF SCA WIND ARE POSSIBLE ACROSS THE LOWER BAY
(4FT WAVES MOUTH OF THE BAY)...AND 5FT SEAS ARE POSSIBLE OUT NEAR
20NM IN THE OCEAN. HIGH PRESSURE RETURNS EARLY NEXT WEEK WITH
LIGHT SSW FLOW RETURNING...ALONG WITH 2-3FT SEAS.
PERSISTENT ONSHORE FLOW WILL RESULT IN AN ELEVATED RIP CURRENT RISK
SATURDAY AND POSSIBLY INTO SUNDAY AS WELL.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH
SATURDAY EVENING FOR MDZ025.
NC...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH
SATURDAY EVENING FOR NCZ102.
VA...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH
SATURDAY EVENING FOR VAZ098>100.
MARINE...NONE.
&&
$$
SYNOPSIS...MPR
NEAR TERM...JDM/MPR
SHORT TERM...BMD
LONG TERM...AJZ
AVIATION...JEF
MARINE...AJZ
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1003 PM PDT Fri Aug 16 2013
.SYNOPSIS...
A slow moving upper level trough will keep unsettled conditions
over the Inland Northwest through Saturday. The trough will pass
all areas by Saturday evening and Sunday delivering locally breezy
winds. Westerly flow will build over the region through the middle
of the week bringing dry weather and seasonable temperatures. The
weather will turn more unsettled toward the end of the next work
week with a return of some thunderstorms possible.
&&
.DISCUSSION...
Evening update: widely scattered to isolated showers and
thunderstorms have been found across northeast Oregon and portions
of the lower Idaho Panhandle this evening. In the past hour or so
more activity has been developing and moving into parts of
southeast WA, including Whitman county. The current trajectory
suggest some may also slip as far north as southern Spokane and
Kootenai county. I`m not thinking they will reach to the Spokane
Metro at this time, but there is the a small potential they
could clip the Post Falls or Coeur d`Alene area. Timing suggests
entering southern Spokane county around 11 pm. These are quick
movers, so may produce some brief heavy rain and gusty winds, maybe
a little bit of hail.
Much of this activity has been found under a ribbon of modest
instability and jet streak and subtle mid-level disturbance moving
along the slowly-advancing cold front. The RUC13 (and other
guidance) continues to show some elevated CAPE and a ribbon of
favorable high level total totals across the southeast through the
night. Hence the continuing isolated shower and thunder threat
through the night. /J. Cote`
&&
.AVIATION...
06Z TAFS: A front will continue to push across the Inland Northwest,
bringing some middle and high clouds, as well as the risk for some
widely sct to isolated -shra/-tsra. The highest threat among TAF
sites will be around KLWS/KPUW...and perhaps KCOE but some may
also be found in the vcnty of KGEG/KSFF through the overnight. The
main threat, aside from lightning, will be possible gusty winds.
Otherwise look for VFR conditions, locally breezy after 18-21Z
Saturday, subsiding again late. /J. Cote`
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 63 84 60 83 60 83 / 10 10 10 0 0 0
Coeur d`Alene 59 84 58 83 56 83 / 10 10 10 0 0 0
Pullman 55 84 52 83 50 86 / 20 10 10 0 0 0
Lewiston 66 92 64 93 62 94 / 20 10 10 0 0 0
Colville 57 88 54 87 53 89 / 10 20 10 0 0 0
Sandpoint 55 82 53 83 50 82 / 10 10 10 0 0 0
Kellogg 58 82 57 81 56 83 / 20 10 10 0 0 0
Moses Lake 61 89 60 88 60 88 / 10 0 0 0 0 0
Wenatchee 66 87 64 88 64 88 / 10 0 0 0 0 0
Omak 61 89 61 89 61 89 / 0 10 10 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
637 PM CDT SUN AUG 18 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND MONDAY
ISSUED AT 256 PM CDT SUN AUG 18 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
CENTERED OVER THE NE U.S...BUT WITH A RIDGE AXIS THAT EXTENDS WEST
INTO THE GREAT LAKES. THE MAIN STORM TRACK REMAINS NORTH OF THE
REGION OVER SOUTHERN CANADA...BUT IS GRADUALLY SINKING TO THE
SOUTH. AS THIS OCCURS...A SHORTWAVE OVER EASTERN MONTANA IS MOVING
EAST AND PRODUCING THUNDERSTORMS...WHICH WILL TRACK TOWARDS THE
REGION TOMORROW. BESIDES TEMPERATURES...SMALL THUNDERSTORM CHANCES
REMAIN THE MAIN FORECAST CONCERNS.
TONIGHT...THE SHORTWAVE TROUGH OVER EASTERN MONTANA WILL MOVE EAST
INTO THE NORTHERN MISSISSIPPI VALLEY BY 12Z MONDAY. THE 850MB
MOISTURE AND INSTABILITY AXES WILL SHIFT INTO NORTHEAST MINNESOTA BY
THIS TIME...WHICH LOOKS TOO FAR WEST FOR MUCH OF AN IMPACT ON THE
FORECAST AREA. OTHERWISE...SCATTERED HIGH CLOUDS WILL BE PASSING
OVERHEAD FOR MUCH OF NIGHT...AND THEN SEE THE HIGH CLOUDS THICKEN
AND LOWER A BIT LATE AS THE SHORTWAVE DRAWS CLOSER. THE PRESSURE
GRADIENT WILL BE TIGHTENING TONIGHT...WHICH SHOULD ALLOW A LIGHT SW
WIND TO PERSIST AND KEEP ANY FOG FROM FORMING. LOWS WILL CONTINUE
THEIR WARMING TREND...AND RESIDE IN THE 50S.
MONDAY...THE SHORTWAVE TROUGH WILL MOVE INTO WISCONSIN. FORCING
WITH THE WAVE APPEARS TO SUBTLY WEAKEN...SO WILL LIKELY NEED THE
HELP OF DIURNAL INSTABILITY TO GET CONVECTION GOING. THE MOISTURE
AXIS WILL BE SNEAKING INTO NORTH-CENTRAL WISCONSIN IN THE
AFTERNOON...BUT PROGGED NAM SOUNDINGS AT 21Z NEAR EAGLE RIVER SHOW
DECENT CAPPING CENTERED AT ABOUT 800 MB. USING A PARCEL OF
82/62...ML CAPES WILL REACH AROUND 1000 J/KG...WHILE CINS REMAIN A
ROBUST 70-80 J/KG. UNLESS THE CAP IS ADVERTISED TOO
STRONGLY...CANNOT SEE MORE THAN ISOLATED STORM DEVELOPMENT GIVEN THE
WEAK FORCING. IF STORMS DO DEVELOP...WEAK SHEAR ALOFT WILL KEEP THE
SEVERE THREAT RATHER LOW. MADE ONLY MINOR TWEAKS TO TIMING AND
COVERAGE OF POPS. DESPITE AN INCREASE IN CLOUD COVER...LOW LEVEL
TEMPS WILL ALSO BE WARMING...AND PUSH HIGHS INTO THE MIDDLE 80S.
.LONG TERM...MONDAY NIGHT THROUGH SUNDAY
ISSUED AT 256 PM CDT SUN AUG 18 2013
TUESDAY THROUGH NEXT WEEKEND WILL BE HIGHLIGHTED WITH ABOVE
NORMAL TEMPERATURES. THE NEXT MAIN CHANCE FOR WIDESPREAD
PRECIPITATION WILL BE STARTING WEDNESDAY AFTERNOON OVER NORTHWEST
WISCONSIN THEN OVER THE REST OF THE STATE WEDNESDAY NIGHT INTO
THURSDAY WITH THE PASSAGE OF A COLD FRONT.
THERE IS A SMALLER CHANCE OF CONVECTION ON TUESDAY OVER THE
NORTHWEST HALF OF THE STATE DUE TO CONTINUED WAA...AND IN A REGION
OF UPPER DIVERGENCE AHEAD OF THE WESTERLIES OVER THE NORTHERN
PLAINS. CONVECTION MAY BE CONFINED TOWARD WESTERN PORTION OF THE
STATE BUT WILL LEAVE PARTS OF NC WI WITH SMALL CHANCE DUE TO TOTAL
TOTALS INCREASE IN THE AFTERNOON.
THE WESTERLY FLOW OVER THE NORTHERN PLAINS BEGINS TO BUCKLE
WEDNESDAY AS A SHORT WAVE TROUGH DEVELOPS OVER SOUTHERN CANADA
AND A COLD FRONT SAGS INTO THE NORTHERN GREAT LAKES REGION
INCLUDING NORTHWEST WISCONSIN. MEDIUM RANGE MODELS ARE IN GOOD
AGREEMENT WITH THE TIMING OFF THIS FRONT AND CONVECTION UNTIL
WEDNESDAY NIGHT FOR MOST LOCATIONS EXCEPT NORTH CENTRAL WISCONSIN.
SEVERE POTENTIAL REMAINS FOR WEDNESDAY AFTERNOON INTO WEDNESDAY
NIGHT. TOTAL TOTALS CLIMB INTO THE LOWER 50S WITH THE FRONT WHILE
PWATS INCREASE TO NEAR 2.00
GFS...GEM DROP THE CONVECTION AND FRONT WELL SOUTH ON THURSDAY
FOR A DRIER TREND WHICH COULD LAST INTO FRIDAY. BUT THE ECMWF
SLOWS THIS FRONT DOWN WHILE A HIGH PRESSURE SYSTEM DRIFTS OVER
THE NORTHERN GREAT LAKES REGION THURSDAY THROUGH FRIDAY.
THE UPPER RIDGE CONTINUES TO BUILD INTO THE WEEKEND FOR MORE HEAT
ALONG WITH CHANCES OF CONVECTION ON THE PERIPHERY OF THE RIDGE OR
MAINLY THE NORTHERN GREAT LAKES REGION.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 635 PM CDT SUN AUG 18 2013
VFR CONDITIONS EXPECTED AS ANTICYCLONE SLOWLY SHIFTS SE OF THE
AREA. ADDED SOME GUSTINESS TO THE TAFS FOR TOMORROW WHEN FAIRLY
DEEP MIXING IS EXPECTED TO OCCUR.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
536 PM CDT SAT AUG 17 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 230 PM CDT SAT AUG 17 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
STRETCHING FROM NEW ENGLAND TO THE WESTERN GREAT LAKES. SHOWERS AND
STORMS ARE OCCURRING OVER SOUTHERN CANADA WITHIN THE MAIN BELT OF
WESTERLIES AND ALSO OVER THE OHIO VALLEY THANKS TO AN UPPER LEVEL
LOW PRESSURE SYSTEM. CONDITIONS ARE QUIET ACROSS WISCONSIN WITH
ONLY DIURNAL CU POPPING. CHANGES ARE MINIMAL OVER THE NEXT 24
HOURS...SO TEMPS AND CLOUDS REMAIN THE MAIN FORECAST CONCERNS.
TONIGHT...AN UPPER LEVEL RIDGE AXIS WILL BE EXTENDING ACROSS THE
NORTHERN GREAT LAKES WHILE THE SURFACE RIDGE AXIS WILL BE OVER
SOUTHERN WISCONSIN. THE CENTER OF THE SURFACE HIGH WILL BE A LITTLE
FARTHER TO THE EAST COMPARED TO LAST NIGHT...WHICH MAY ALLOW A
SLIGHT SW WIND TO STICK AROUND. THE MAIN BELT OF WESTERLIES WILL REMAIN
POSITIONED TO OUR NORTH OVER MANITOBA AND ONTARIO AND SOME HIGH
CLOUDS MAY DRIFT ACROSS NORTHERN WISCONSIN. NEITHER THE WIND NOR
HIGH CLOUDS SHOULD IMPACT TEMPS MUCH WHICH WILL BE A COUPLE
DEGREES WARMER THAN LAST NIGHT. PATCHY GROUND FOG SHOULD ALSO
DEVELOP LATE...THAT WILL BE A LITTLE MORE WIDESPREAD OVER N-C
WISCONSIN COMPARED TO ELSEWHERE.
SUNDAY...THOUGH RIDGING IN THE UPPER LEVELS WILL BE
OVERHEAD...SURFACE HIGH PRESSURE WILL DRIFT A LITTLE FARTHER EAST IN
RESPONSE TO HEIGHT FALLS OCCURRING OVER THE FAR NORTHERN PLAINS AND
LAKE SUPERIOR REGION. SHOULD SEE A LITTLE MORE HIGH CLOUDS IN
ADDITION TO THE DIURNAL CU THAT WILL POP MIDDAYISH. MIXING HEIGHTS
ARE PROJECTED TO BE A LITTLE LOWER TOMORROW AFTERNOON...BUT LOWS WILL
BE A LITTLE WARMER...SO WILL GO WITH HIGHS ABOUT A DEGREE WARMER
THAN TODAY.
.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 230 PM CDT SAT AUG 17 2013
UPPER RIDGING ACROSS THE WESTERN TWO THIRDS OF THE COUNTRY WILL
LEAD TO WARMER TEMPERATURES BUT MINIMAL PRECIPITATION CHANCES FOR
MUCH OF THE NEW WORK WEEK. THE NORTHERN STREAM ACROSS CANADA WILL
BE THE PRIMARY SOURCE OF SYSTEMS WHICH MAY BRUSH OVER THE NORTHERN
GREAT LAKES REGION AT TIMES.
THE NAM AND GFS CONTINUE TO FOLLOW THE TREND OF A FEW WEAK SHORT
WAVES GLANCING OVER NORTHERN WISCONSIN IN THE SUBTLE WAA FLOW FOR
LATE TONIGHT INTO MONDAY WITH ANOTHER TOWARD TUESDAY AFTERNOON.
PROGS CONTINUE TO INDICATE A STRONGER SHORT WAVE TROUGH WITH COLD
FRONT SLIDING OVER THE GREAT LAKES REGION WEDNESDAY AFTERNOON
INTO WEDNESDAY NIGHT. TOTAL TOTALS CLIMB TO NEAR 50 ALONG AND NEAR
THE FRONT...SO NO NEED TO CHANGE THE GOING THOUGHTS OF SVR
POTENTIAL IN THE HWO AT THIS TIME.
PCPN MAY END THURSDAY INTO THURSDAY NIGHT DEPENDING ON THE SOUTHWARD
EXTENT OF THE FRONT BUT RETURN FLOW SETTING UP IN THE WAKE OF A
SUBTLE HIGH PRESSURE SYSTEM WILL BRING THE POTENTIAL OF MORE
SHOWERS AND STORMS BACK INTO THE AREA BY NEXT WEEKEND.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 533 PM CDT SAT AUG 17 2013
SFC HIGH WILL BE A LITTLE FARTHER OFF TO THE SE TNGT...SO THERE WL
BE A BIT OF A SFC PRESSURE GRADIENT ACRS THE AREA...BUT PROBABLY
NOT ENOUGH TO PREVENT DECOUPLING AND WINDS GOING CALM AT MOST
LOCATIONS. EXPECT SOME MIFG TO DEVELOP AGAIN TNGT. GIVEN CHGS
DESCRIBED ABV...CONDITIONS ACRS N-C WI WL BE A BIT LESS FAVORABLE
THAN YDA.
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......SKOWRONSKI
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 230 PM CDT SAT AUG 17 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
STRETCHING FROM NEW ENGLAND TO THE WESTERN GREAT LAKES. SHOWERS AND
STORMS ARE OCCURRING OVER SOUTHERN CANADA WITHIN THE MAIN BELT OF
WESTERLIES AND ALSO OVER THE OHIO VALLEY THANKS TO AN UPPER LEVEL
LOW PRESSURE SYSTEM. CONDITIONS ARE QUIET ACROSS WISCONSIN WITH
ONLY DIURNAL CU POPPING. CHANGES ARE MINIMAL OVER THE NEXT 24
HOURS...SO TEMPS AND CLOUDS REMAIN THE MAIN FORECAST CONCERNS.
TONIGHT...AN UPPER LEVEL RIDGE AXIS WILL BE EXTENDING ACROSS THE
NORTHERN GREAT LAKES WHILE THE SURFACE RIDGE AXIS WILL BE OVER
SOUTHERN WISCONSIN. THE CENTER OF THE SURFACE HIGH WILL BE A LITTLE
FARTHER TO THE EAST COMPARED TO LAST NIGHT...WHICH MAY ALLOW A
SLIGHT SW WIND TO STICK AROUND. THE MAIN BELT OF WESTERLIES WILL REMAIN
POSITIONED TO OUR NORTH OVER MANITOBA AND ONTARIO AND SOME HIGH
CLOUDS MAY DRIFT ACROSS NORTHERN WISCONSIN. NEITHER THE WIND NOR
HIGH CLOUDS SHOULD IMPACT TEMPS MUCH WHICH WILL BE A COUPLE
DEGREES WARMER THAN LAST NIGHT. PATCHY GROUND FOG SHOULD ALSO
DEVELOP LATE...THAT WILL BE A LITTLE MORE WIDESPREAD OVER N-C
WISCONSIN COMPARED TO ELSEWHERE.
SUNDAY...THOUGH RIDGING IN THE UPPER LEVELS WILL BE
OVERHEAD...SURFACE HIGH PRESSURE WILL DRIFT A LITTLE FARTHER EAST IN
RESPONSE TO HEIGHT FALLS OCCURRING OVER THE FAR NORTHERN PLAINS AND
LAKE SUPERIOR REGION. SHOULD SEE A LITTLE MORE HIGH CLOUDS IN
ADDITION TO THE DIURNAL CU THAT WILL POP MIDDAYISH. MIXING HEIGHTS
ARE PROJECTED TO BE A LITTLE LOWER TOMORROW AFTERNOON...BUT LOWS WILL
BE A LITTLE WARMER...SO WILL GO WITH HIGHS ABOUT A DEGREE WARMER
THAN TODAY.
.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 230 PM CDT SAT AUG 17 2013
UPPER RIDGING ACROSS THE WESTERN TWO THIRDS OF THE COUNTRY WILL
LEAD TO WARMER TEMPERATURES BUT MINIMAL PRECIPITATION CHANCES FOR
MUCH OF THE NEW WORK WEEK. THE NORTHERN STREAM ACROSS CANADA WILL
BE THE PRIMARY SOURCE OF SYSTEMS WHICH MAY BRUSH OVER THE NORTHERN
GREAT LAKES REGION AT TIMES.
THE NAM AND GFS CONTINUE TO FOLLOW THE TREND OF A FEW WEAK SHORT
WAVES GLANCING OVER NORTHERN WISCONSIN IN THE SUBTLE WAA FLOW FOR
LATE TONIGHT INTO MONDAY WITH ANOTHER TOWARD TUESDAY AFTERNOON.
PROGS CONTINUE TO INDICATE A STRONGER SHORT WAVE TROUGH WITH COLD
FRONT SLIDING OVER THE GREAT LAKES REGION WEDNESDAY AFTERNOON
INTO WEDNESDAY NIGHT. TOTAL TOTALS CLIMB TO NEAR 50 ALONG AND NEAR
THE FRONT...SO NO NEED TO CHANGE THE GOING THOUGHTS OF SVR
POTENTIAL IN THE HWO AT THIS TIME.
PCPN MAY END THURSDAY INTO THURSDAY NIGHT DEPENDING ON THE SOUTHWARD
EXTENT OF THE FRONT BUT RETURN FLOW SETTING UP IN THE WAKE OF A
SUBTLE HIGH PRESSURE SYSTEM WILL BRING THE POTENTIAL OF MORE
SHOWERS AND STORMS BACK INTO THE AREA BY NEXT WEEKEND.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1228 PM CDT SAT AUG 17 2013
VFR CONDITIONS WILL PROVIDE GOOD FLYING WEATHER OVER THE
TAF PERIOD. MOS GUIDANCE SHOWS THAT PATCHY GROUND FOG DOES NOT LOOK
TO BE AS DENSE OR WIDESPREAD BETWEEN 08-12Z SUNDAY MORNING COMPARED
TO THIS MORNING. STILL EXPECT MORE FOG OVER NORTH-CENTRAL WISCONSIN
COMPARED TO ELSEWHERE THOUGH.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......MPC
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1048 AM CDT SAT AUG 17 2013
.UPDATE...ANOTHER QUIET DAY IN STORE FOR SOUTHERN WISCONSIN.
CHANGES IN THE TODAY PERIOD WERE LIMITED TO ADJUSTING FOR TRENDS.
SKY COVER WAS BUMPED UP A BIT...WITH AT LEAST SCATTERED CUMULUS
EXPECTED GIVEN PROXIMITY SOUNDINGS AND RESIDUAL LOW-LEVEL
MOISTURE...CU RULE...AND GOES-R PG WRF ABI SYNTHETIC IMAGERY.
GIVEN HIGHS YESTERDAY AND RAP PROXIMITY SOUNDINGS...NEAR GROUND
SUPERADIABATIC LAPSE RATES ARE ANTICIPATED. THIS WILL RESULT IN
FORECAST HIGHS REMAINING AROUND 80/LOW 80S AWAY FROM THE LAKESHORE
COUNTIES...TO MID/UPPER 70S FAR EAST.
ET
&&
.AVIATION/18Z TAFS/...VFR CONDITIONS ARE EXPECTED THIS AFTERNOON
AND THIS EVENING ACROSS TAF SITES...AND AGAIN FOR MOST OF SUNDAY.
HIGH PRESSURE WILL REMAIN SOUTHEAST OF THE REGION THROUGH THE
WEEKEND. THE HIGH WILL BRING QUIET WEATHER. SCATTERED DIURNAL
CUMULUS CLOUDS ARE EXPECTED THIS AFTERNOON AND AGAIN SUNDAY
AFTERNOON.
LIGHT SOUTHEAST WINDS ARE EXPECTED THIS AFTERNOON INTO THE EARLY
EVENING...THEN BECOMING LIGHT/CALM TONIGHT INTO EARLY SUNDAY.
LIGHT SOUTH WINDS ARE EXPECTED AT MADISON ON SUNDAY...WITH LIGHT
SOUTHEAST WINDS AT THE EASTERN SITES.
FOG WITH VISIBILITIES DOWN TO OR BELOW AIRPORT MINIMUMS ARE
EXPECTED AT KENOSHA BY 05Z SUNDAY...LINGERING UNTIL AROUND 13Z
SUNDAY. MAY SEE FOG WITH VISIBILITIES DOWN TO ALTERNATE MINIMUMS
AT TIMES AT WAUKESHA FROM 09Z UNTIL 12Z SUNDAY. MADISON AND
MILWAUKEE MAY SEE VFR FOG DURING THIS TIME.
WOOD
&&
.PREV DISCUSSION... /ISSUED 326 AM CDT SAT AUG 17 2013/
SHORT TERM...
TODAY AND TONIGHT...FORECAST CONFIDENCE HIGH
AT THE SFC...HIGH PRESSURE WILL CONTINUE TO PREVAIL FROM NEW ENGLAND
WWD INTO PORTIONS OF THE UPPER MS RIVER VALLEY...INCLUDING SRN WI.
ALOFT...AN UPPER LOW WILL REMAIN OVER THE MID MS RIVER VALLEY WITH
SOME RIDGING AND WARMING ALOFT THAT WILL OVERSPREAD SRN WI FROM THE
NRN PLAINS. THIS WILL RESULT IN LESS CU DEVELOPMENT THAN RECENT DAYS
WITH A CONTINUED DRY AND WARMING AIRMASS IN PLACE. NEAR GROUND
SUPERADIABATIC LAPSE RATES WITH 925 MB TEMPS AROUND 19C YIELDS LOWER
80S FOR TODAY INLAND FROM THE LAKE BREEZE. LAKE BREEZE WILL DEVELOP
BY 15Z SIMILAR TO YESTERDAY. GOOD RADIATIONAL COOLING CONDITIONS
ONCE AGAIN TNT BUT AIRMASS IS FAIRLY DRY SO EXPECT GROUND FOG ONLY
IN THE TYPICAL LOW LYING AREAS.
SUNDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE HIGH.
SURFACE HIGH PRESSURE WILL CONTINUE TO HOLD STRONG OVER THE GREAT
LAKES REGION THROUGH EARLY NEXT WEEK BRINGING MOSTLY CLEAR SKIES AND
DRY WEATHER. MEANWHILE...A WEAK MID LEVEL LOW WILL DRIFT ACROSS THE
OHIO RIVER VALLEY AND ALLOW FOR THAT STRONG AND WARM RIDGE OVER THE
WESTERN U.S. TO NOSE INTO SOUTHERN WISCONSIN. LOOK FOR A GRADUAL
WARMING TREND THROUGH THIS PERIOD...FROM AROUND 80 SUNDAY TO THE
UPPER 80S/90 ON WEDNESDAY.
A FEW WEAK UPPER TROUGHS ARE FORECAST BY THE MODELS TO RIDE OVER THE
RIDGE AND PASS ACROSS THE GREAT LAKES NEXT WEEK. THE FIRST WAVE
MONDAY NIGHT WILL BE DRY WITH PLENTY OF AGREEMENT BETWEEN THE MODELS
WHERE THEY ALL SHOW A STRONG CAP AROUND 750MB.
LONG TERM...
WEDNESDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM TO LOW.
THERE IS A STRONG UPPER TROUGH THAT WILL RIDE OVER THE RIDGE THROUGH
SOUTHERN CANADA MID WEEK. THIS WILL BE OUR NEXT WEATHER MAKER AS IT
REACHES LAKE SUPERIOR WED NIGHT. THERE ARE SOME SIGNIFICANT
DIFFERENCES BETWEEN THE MODELS FOR WED NIGHT/THU NOW. THE GFS PHASES
THAT UPPER TROUGH WITH A WEAKER SHORTWAVE MOVING THROUGH THE
NORTHERN PLAINS/UPPER MIDWEST AND DROPS A COLD FRONT ALL THE WAY
DOWN THROUGH WI INTO IA AND IL. THE LATEST 00Z ECMWF DOES NOT PHASE
THOSE TWO FEATURES SO THE FRONT SAGS INTO SOUTHERN WI ON THU AND
THEN GETS PUSHED BACK NORTH FOR FRI. THE CANADIAN MODEL IS SOMEWHERE
IN BETWEEN.
THE ECMWF WOULD SUGGEST THAT AT LEAST THE SOUTHERN HALF OF THE MKX
FORECAST AREA WOULD STAY DRY AND VERY WARM THROUGH THE LATTER HALF
OF NEXT WEEK...HIGHS IN THE LOWER 90S. THE GFS SUGGESTS A PERIOD OF
THUNDERSTORMS ALONG THE FRONT AND THEN COOLING BACK OFF INTO THE
UPPER 70S ON FRI. STAY TUNED.
AVIATION/12Z TAFS/...DENSE FOG AT KENW WILL CONTINUE UNTIL
SUNRISE...THEN QUICKLY BURN OFF. POSSIBLY BRIEF MVFR VSBYS MAY OCCUR
AT KMSN AND KUES AROUND SUNRISE. OTHERWISE FEW-SCT FAIR WX CU AROUND
6-8 KFT DURING THE AFTERNOON. ANOTHER CLEAR NIGHT WITH HIGH PRESSURE
IN CONTROL. FOG EXPECTED IN THE TYPICAL LOW LYING AREAS SO EXPECT
KENW TO HAVE DENSE FOG AT TIMES LATE AT NIGHT WITH MVFR VSBYS
POSSIBLY AROUND SUNRISE SUNDAY AT KMSN AND KUES.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...ET/WOOD
TODAY/TONIGHT AND AVIATION/MARINE...GEHRING
SUNDAY THROUGH FRIDAY...MRC
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1110 PM CDT FRI AUG 16 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND SATURDAY
ISSUED AT 241 PM CDT FRI AUG 16 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOWS A SPRAWLING
HIGH PRESSURE SYSTEM STRETCHING FROM THE NORTHERN MISSISSIPPI VALLEY
TO NEW ENGLAND. AS ONE SHORTWAVE DIGS OVER THE SOUTHERN PLAINS
WHILE ANOTHER SHIFTS EAST OVER MANITOBA...MID-LEVEL RIDGING IS
GRADUALLY BUILDING EAST OVER THE NORTHERN PLAINS. THIS PATTERN WILL
CONTINUE TO LEAD TO QUIET WEATHER OVER THE NEXT SEVERAL
DAYS...MAKING CLOUDS AND TEMPS THE MAIN FORECAST CONCERN IN THE
SHORT TERM.
TONIGHT...HIGH PRESSURE WILL REMAIN OVER THE REGION BENEATH BUILDING
HEIGHTS IN THE MID AND UPPER LEVELS. WISCONSIN WILL BE POSITIONED
BETWEEN WEATHER SYSTEMS NORTH AND SOUTH OF THE REGION. WITH LOW
PWATS AND MOSTLY CLEAR CONDITIONS...WILL LIKELY SEE PATCHY GROUND
FOG FORM LATE TONIGHT ACROSS THE SANDY SOIL AREAS AND RIVER VALLEYS.
WENT BELOW MOS GUIDANCE FOR LOWS...WHICH SHOULD BE A FEW DEGREES
WARMER THAN LAST NIGHT.
SATURDAY...HIGH PRESSURE THROUGH THE COLUMN WILL PROVIDE ANOTHER
QUIET AND SUNNY DAY. START TO GET A LITTLE MORE RETURN FLOW ACROSS
THE REGION...WHICH SHOULD LEAD TO SLIGHTLY WARMER HIGH TEMPS AND
MORE HUMIDITY. HIGHS MAINLY IN THE LOW TO MID 80S...EXCEPT COOLER
NEAR THE LAKE.
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
ISSUED AT 241 PM CDT FRI AUG 16 2013
MODELS ARE NOW IN GOOD AGREEMENT WITH OVERALL PATTERN.
THEY BRING UPPER RIDGING INTO THE NORTHERN PLAINS AND WESTERN
GREAT LAKES THROUGH MIDWEEK. A SHORT WAVE TROUGH MOVING ALONG THE
CANADIAN BORDER WILL SUPPRESS THE RIDGING A BIT SUNDAY NIGHT AND
MONDAY AND COULD PRODUCE SCATTERED THUNDERSTORMS IN THE FAR NORTH.
PROLONGED SOUTHERLY FLOW AND WARMER TEMPERATURES ALOFT WILL
COMBINE TO PRODUCE VERY WARM AND MORE HUMID CONDITIONS DURING THE
MIDDLE OF THE WEEK WITH THE WARMEST WEATHER SINCE MID JULY. THE
HEAT SHOULD SUBSIDE AS A COLD FRONT MOVES THROUGH THURSDAY AND
THURSDAY NIGHT. COOLER AND DRIER AIR EXPECTED FRIDAY THROUGH
SUNDAY.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1107 PM CDT FRI AUG 16 2013
HIGH PRESSURE AND VFR CONDITIONS WILL PROVIDE GOOD FLYING
WEATHER THROUGH MOST OF THIS TAF PERIOD. THE EXCEPTION WILL BE
OVERNIGHT...WHEN SOME SOME PATCHY GROUND FOG WILL IMPACT THE
REGION THROUGH ABOUT 12Z/SAT. THE FOG SHOULD BE MOST WIDESPREAD
AND DENSE OVER NORTH CENTRAL WISCONSIN.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......RDM
AVIATION.......KIECKBUSCH
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
412 PM MDT SAT AUG 17 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 412 PM MDT SAT AUG 17 2013
VISIBLE SATELLITE IMAGERY SHOWS A HIGH LAYER OF SMOKE CONTINUING TO
MOVE SOUTHEAST OVER MUCH OF THE FORECAST AREA TODAY...WITH SOME CU
DEVELOPING OVER THE MOUNTAINS ON THE WESTERN PERIPHERY OF THE SMOKE
LAYER. LLVL INSTABILITY LOOKS WEAK OUT WEST BUT LAPSE RATES
ARE QUITE STEEP WITH SFC TEMPERATURES WARMING INTO THE MID TO UPPER
80S. WITH AN UPPER LEVEL SHORTWAVE MOVING UP FROM UTAH...COULD SEE
SOME MORE VIGOROUS CU TOWERS DEVELOP INTO ISOLATED SHOWERS AND
THUNDERSTORMS LATE THIS AFTERNOON AND EARLY EVENING MAINLY ALONG AND
WEST OF THE LARAMIE RANGE. RUC MODEL HINTS AT A FEW TRYING TO
DEVELOP ACROSS THE EASTERN PLAINS AS WELL IN MOIST UPSLOPE
FLOW...BUT AM NOT CONFIDENT THE CAP WILL BREAK IN THIS AREA TO
DEVELOP MUCH MORE THAN VERY LIGHT SHOWERS. 12Z UPSTREAM RAOBS AND
NAM FORECAST OBS SUGGEST A VERY DEEP MIXING LAYER UP TO 500 MB OR
SO THIS AFTERNOON...HOWEVER WINDS ALOFT REMAIN WEAK. CURRENTLY
SEEING A FEW LOCATIONS ACROSS THE REGION GUSTING 20 TO 25 MPH OR
SO...AND THINK THAT WILL CONTINUE TO BE THE TREND THROUGH THE REST
OF THE AFTERNOON. HUMIDITIES HAVE DROPPED TO THE UPPER SINGLE
DIGITS TO LOW TEENS WITHIN THE LEESIDE TROUGH AND POINTS FURTHER
WEST IN THE ZONE OF GUSTY WINDS...BUT AGAIN WINDS SHOULD REMAIN
BELOW CRITICAL FIRE WEATHER THRESHOLDS SO WILL JUST CONTINUE TO
MENTION HEIGHTENED FIRE WEATHER CONCERNS FOR LATE THIS AFTERNOON.
THE LEESIDE PRESSURE TROUGH WILL REMAIN OVER THE CWA TONIGHT...WITH
MOIST SOUTH TO SOUTHEAST FLOW TO CONTINUE OVER THE EASTERN PLAINS.
WILL GO WITH THE A PERSISTENCE FORECAST WHICH MEANS THE LOW
STRATUS DECK AND FOG WILL RETURN FOR EASTERN PORTIONS OF THE
NEBRASKA PANHANDLE EARLY SUNDAY MORNING. SIMILAR TO THE PREVIOUS
COUPLE OF NIGHTS...THE FOG COULD BE DENSE AT TIMES WITH
VISIBILITIES DROPPING TO ONE HALF MILE OR LESS. THE STRATUS WILL
STEADILY MIX OUT AFTER SUNRISE.
A STRONGER SHORTWAVE WILL MOVE EAST ACROSS THE NORTHERN ROCKIES AND
PLAINS ON SUNDAY AND WILL DROP A WEAK COOL FRONT ACROSS THE FORECAST
AREA LATE SUNDAY AFTERNOON AND EVENING. AHEAD OF THE FRONT...WILL
SEE BREEZY CONDITIONS RETURN TO THE FORECAST AREA IN THE AFTERNOON.
GUIDANCE SUGGESTS THE RETURN OF THE MONSOONAL PLUME TOMORROW AS
WELL SO AFTERNOON HUMIDITIES WILL NOT DRY OUT AS MUCH AS TODAY.
HOWEVER...CONDITIONS WILL REMAIN DRY AND BREEZY ALONG AND WEST OF
THE LARAMIE RANGE SO FIRE WEATHER CONCERNS WILL REMAIN ELEVATED
THROUGH EARLY SUNDAY AFTERNOON. THE INCREASE IN MOISTURE AND FRONT
MOVING SOUTH ACROSS THE REGION WILL BRING A BROADER COVERAGE OF
SHOWERS AND TSTORMS TO THE FORECAST AREA LATE IN THE AFTERNOON AND
EVENING. LOOKING AT MODERATE RAINFALL ALONG WITH GUSTY WINDS FROM
THIS ACTIVITY.
WINDS BEHIND THE FRONT WILL QUICKLY VEER FROM THE NORTH BACK TO THE
SOUTHEAST ON MONDAY BUT WILL REMAIN RELATIVELY LIGHT UNDER WEAK FLOW
ALOFT WITH MINIMAL ENERGY MOVING OVERHEAD. SO COULD SEE A FEW
AFTERNOON SHOWERS AND THUNDERSTORMS ONCE AGAIN IN THIS WEAK UPSLOPE
REGIME...BUT COVERAGE WILL BE LESS THAN SUNDAY DUE TO LACK OF
SIGNIFICANT FORCING.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 412 PM MDT SAT AUG 17 2013
LOOKS LIKE A TRANSITION TO A MORE MOIST AND WETTER PATTERN COULD BE
IN STORE FOR THE EXTENDED ESPECIALLY WEDNESDAY INTO FRIDAY. RIDGE
WILL BE CENTERED AROUND COLORADO ON TUESDAY WITH THE BEST MONSOONAL
MOISTURE TO THE SOUTHWEST ACROSS WESTERN COLORADO AND UTAH. BOTH
THE GFS AND ECMWF HAVE THE RIDGE SHIFTING EASTWARD TOWARD THE
CENTRAL PLAINS BY LATE WEDNESDAY AND INTO THURSDAY. THIS CAUSES
MIDLEVEL FLOW TO GO SOUTHERLY WITH 700-500MB MOISTURE ON THE
INCREASE. AT THE SAME TIME...A SFC HIGH WILL BE POSITIONED OVER THE
DAKOTAS BY WEDNESDAY NIGHT WITH EAST WINDS TRANSPORTING HIGHER SFC
DEWPOINTS UP ALONG THE LARAMIE RANGE. HAVE CHANCE TO SLIGHT CHANCE
POPS OVER MUCH OF SOUTHEAST WY ON WEDNESDAY AND THURSDAY AFTNS AND
EVENINGS WITH PW VALUES RISING UP TO AROUND 1 INCH. WHILE CAPE
VALUES ARE NOT PARTICULARLY HIGH (LESS THAN 1000 J/KG)...STEERING
FLOW IS WEAK (AROUND 10-15 KTS) SO HEAVY RAIN WILL BE THE PRIMARY
THREAT. TUESDAY WILL LIKELY BE THE WARMEST AND DRIEST DAY BEFORE
INCREASING MOISTURE AND CLOUD COVER CAUSE HIGHS TO FALL AROUND 5-10
DEGREES FOR WEDNESDAY THROUGH FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY MORNING)
ISSUED AT 412 PM MDT SAT AUG 17 2013
VFR CONDITIONS WILL OCCUR OVER THE REGION TODAY AND MUCH OF
TONIGHT...WITH A FEW ISOLATED THUNDERSTORMS POSSIBLE OVER THE
MOUNTAINS LATE THIS AFTERNOON AND EARLY EVENING. WIND GUSTS TO
AROUND 20 KTS ARE LIKELY THIS AFTERNOON AT MOST TERMINALS AND WILL
EASE THROUGH THE EARLY EVENING. FOR LATE TONIGHT...PATCHY FOG AND
LOW CIGS WILL MAKE A RETURN TO THE NEBRASKA PANHANDLE WITH MVFR TO
IFR CONDITIONS EXPECTED IN THIS AREA. CONDITIONS WILL IMPROVE LATE
SUNDAY MORNING...WITH A BROADER COVERAGE OF SHOWERS AND
THUNDERSTORMS EXPECTED LATE SUNDAY AFTERNOON OVER MUCH OF THE
FORECAST AREA.
&&
.FIRE WEATHER...
ISSUED AT 412 PM MDT SAT AUG 17 2013
AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL REMAIN OVERHEAD THROUGH
EARLY NEXT WEEK AND WILL MAINTAIN ABOVE NORMAL TEMPERATURES
THROUGH THIS TIME. MOSTLY DRY CONDITIONS WILL CONTINUE FOR THE
REST OF THIS EVENING OUTSIDE OF AN ISOLATED THUNDERSTORM OR TWO
DEVELOPING OVER THE MOUNTAINS. AFTERNOON HUMIDITIES HAVE DROPPED TO
BETWEEN 5 AND 15 PERCENT ALONG AND WEST OF THE LARAMIE RANGE
WITHIN A DRY AND WELL MIXED ENVIRONMENT. IN ADDITION...WINDS IN
THIS AREA ARE GUSTING BETWEEN 20 AND 25 MPH AT TIMES. DRY
CONDITIONS WILL PERSIST THROUGH LATE THIS AFTERNOON BUT WINDS
SHOULD STEADILY EASE. THEREFORE...THESE HEIGHTENED FIRE WEATHER
CONDITIONS ARE EXPECTED TO IMPROVE THROUGH THE REMAINDER OF TODAY.
FOR SUNDAY...MORE MIDLEVEL MOISTURE WILL MOVE OVERHEAD WHICH WILL
KEEP AFTERNOON HUMIDITIES BETWEEN 15 AND 20 PERCENT. GUSTS WILL
ONCE AGAIN BE AROUND 20 TO 25 MPH AND WILL BECOME MORE WIDESPREAD
OVER AND NEAR THE MOUNTAINS IN THE AFTERNOON. IN ADDITION...A WEAK
FRONT MOVING SOUTH ACROSS THE DISTRICT WILL BRING A BETTER
COVERAGE OF SHOWERS AND THUNDERSTORMS IN THE LATE AFTERNOON AND
EVENING.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM...RJM
LONG TERM...FINCH
AVIATION...RJM
FIRE WEATHER...RJM
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
955 PM MST SUN AUG 18 2013
.SYNOPSIS...
VERY WARM DAYS WITH A RELATIVELY HIGH DEGREE OF MONSOON MOISTURE
WILL CONTINUE THE THREAT OF AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS THIS WEEK OVER SOUTHWEST AND SOUTH CENTRAL ARIZONA.
SHOWER INTENSITY AND COVERAGE WILL VARY FROM DAY TO DAY. A VERY WARM
AIRMASS OVER THE REGION HAS THE POTENTIAL TO RESULT IN DESERT HIGH
TEMPERATURES NEAR THE 110 DEGREE MARK THROUGH THURSDAY.
&&
.DISCUSSION...
UPPER LEVEL LOW CENTERED JUST OFF THE CENTRAL CALIFORNIA COAST
HELPED ADVECT MOISTURE INTO THE MOHAVE DESERT REGION TODAY ALONG
WITH UPPER LEVEL DIFFLUENCE TO AID STORM DEVELOPMENT. IT ALSO
PROVIDED SOME VERTICAL WIND SHEAR TO AID IN STORM INTENSITY. MOST OF
THE ACTIVITY WAS OUTSIDE OF OUR FORECAST AREA IN VEF CWA.
HOWEVER...ON THE EASTERN PERIPHERY OF THE INFLUENCE FROM THE UPPER
LOW...SOUTHERN ARIZONA HAD ANOTHER FAIRLY ACTIVE NIGHT. WHILE
OUTFLOWS DID MAKE THEIR WAY THROUGH THE PHOENIX METRO AREA...ONLY
ISOLATED STORMS HAVE MANAGED TO FORM...THIS TIME OVER THE WEST
VALLEY. IR IMAGERY SHOWS A LARGE AREA OF COLD CLOUD TOPS...FROM
DECAYING CONVECTION ALONG AND NEAR THE MEXICO BORDER. THIS
MAY HAVE BEEN AIDED BY AN APPROACHING WAVE NEAR CENTRAL AND SOUTHERN
BAJA MEXICO. BOTH THE 00Z GFS AND NAM FORECAST THE WAVE TO MOVE
SLOWLY NORTHWARD ACROSS BAJA...NORTHWEST MEXICO...AND ARIZONA
TONIGHT AND MONDAY. IN THE PROCESS...THE MODELS DEPICT VARYING
AMOUNTS OF UPPER LEVEL DIVERGENCE AHEAD OF THE WAVE AXIS. THIS MAY
HELP KEEP PESKY STORM ACTIVITY GOING OVERNIGHT INTO THE MORNING
HOURS. THERE ARE ALSO SOME INDICATIONS IN RADAR DATA OF AN MCV
ASSOCIATED WITH THE THE SOUTHERN ARIZONA STORM REMNANTS. EARLIER
RUNS OF HRRR MODEL FORECAST THE BORDERLAND CONVECTION PRETTY WELL.
IT ALSO DID A PRETTY GOOD JOB OF NOT SHOWING WIDESPREAD STORM
ACTIVITY OVER THE SOUTH-CENTRAL DESERTS THIS EVENING. THE LATEST RUN
IS NOT THAT OPTIMISTIC WITH LATE NIGHT SHOWERS...NOR ARE THE GFS AND
NAM...BUT WILL HOLD ON TO SLIGHT CHANCE POPS FOR THE AFOREMENTIONED
REASONS. WITH LINGERING CLOUD COVER...OVERNIGHT TEMPS WILL REMAIN
WARM AND THUS WILL ALLOW EXCESSIVE HEAT WARNING TO EXPIRE EARLY
MONDAY.
&&
.PREVIOUS DISCUSSION ISSUED 255 PM...
TONIGHT...
AN UNSCHEDULED MORNING YUMA PROVING GROUNDS (YPG) WEATHER BALLOON
SOUNDING SHOWED A PLUME OF RELATIVELY HIGH LOW LEVEL MOISTURE MOVING
NORTH UP THE COLORADO RIVER. AFTERNOON WATER VAPOR IMAGERY ALSO
SHOWED A NOTICEABLE DEGREE OF UPPER LEVEL DIFLUENCE ACROSS SOUTHEAST
CA...SOUTHERN NEVADA...AND NORTHWEST MEXICO RELATED TO THE PACIFIC
TROF ALONG THE CENTRAL CA COAST. THEREFORE THE CHANCE OF SHOWERS AND
THUNDERSTORMS WILL CONTINUE ACROSS PARTS SOUTHEAST CA AND THE
COLORADO RIVER VALLEY THROUGH THIS EVENING. A BROAD BRUSH THREAT FOR
SHOWERS AND THUNDERSTORMS WILL CONTINUE ELSEWHERE IN SOUTHWEST AND
SOUTH CENTRAL AZ THE REMAINDER OF THE AFTERNOON AND EVENING...WITH A
HINT THAT CONVECTIVE ACTIVITY MAY LAST INTO THE NIGHT DUE TO A
DISTURBANCE MOVING INTO THE REGION FROM THE BAJA.
MONDAY THROUGH FRIDAY...
SOME DRYING IS EXPECTED OVER PORTIONS OF SOUTHEAST CA AND THE
COLORADO RIVER RELATED TO THE CA TROF MONDAY AND TUESDAY. OTHERWISE
THE REMAINDER OF AZ WILL BE UNSEASONABLY WARM AND MARGINALLY MOIST.
A THREAT OF AFTERNOON AND EVENING SHOWER AND THUNDERSTORM ACTIVITY
WILL CONTINUE THIS WEEK...WITH STORM INTENSITY AND COVERAGE VARYING
FROM DAY TO DAY. LITTLE CHANGE IN ATMOSPHERIC HEIGHTS AND THICKNESS
VALUES PORTEND A CONTINUATION OF UNSEASONABLY WARM DAYS...WITH
DESERT HIGHS POTENTIALLY HITTING THE 110 DEGREE MARK THROUGH
THURSDAY. HOWEVER...HIGH TEMPERATURE VARIABILITY WILL OF COURSE
RESULT FROM NEARBY CLOUD AND SHOWER DEVELOPMENT.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
STORM ACTIVITY OVER THE LOWER DESERTS IS WINDING DOWN THIS EVENING.
SPOTTY LIGHT SHOWERS AND ISOLATED THUNDERSTORMS WILL REMAIN A
POSSIBILITY DURING THE OVERNIGHT HOURS AS AN UPPER LEVEL WAVE
APPROACHES FROM BAJA MEXICO BUT NOT ENOUGH TO PUT PREVAILING SHOWERS
OR TEMPO SHWRS IN THE TAFS. SURFACE WINDS WILL BE VARIABLE ACROSS
THE METRO AREA OVERNIGHT BEFORE SLOWLY TRENDING TO WESTERLY
DIRECTIONS MONDAY AFTERNOON. DEBRIS CLOUDS WILL DECREASE TOWARD
MORNING.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
CLOUDINESS WILL INCREASE OVERNIGHT...MAINLY ABOVE 10 KFT MSL...AHEAD
OF AN APPROACHING UPPER LEVEL WAVE CURRENTLY NEAR BAJA MEXICO.
ISOLATED SHWRS/TSTMS WILL BE POSSIBLE OVER THE REGION BUT
PROBABILITY TO LOW TO SHOW PREVAILING OR TEMPO SHWRS/TSTMS IN THE
TAFS. SURFACE WINDS WILL FAVOR SOUTHERLY DIRECTIONS THROUGH THE DAY
MONDAY.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
WEDNESDAY THROUGH SUNDAY...
THROUGH MIDWEEK...STRONG RIDGING ALOFT OVER THE DESERT SOUTHWEST
WILL KEEP TEMPERATURES ABOVE NORMAL...AND MONSOON THUNDERSTORM
ACTIVITY CONFINED MAINLY TO THE HIGHER TERRAIN OF SOUTH-CENTRAL
ARIZONA WITH ISOLATED THUNDERSTORMS POSSIBLE OVER THE DESERTS OF
SOUTH-CENTRAL ARIZONA. A DEEPER MONSOON MOISTURE PROFILE IS EXPECTED
TO WORK BACK INTO THE REGION LATER IN THE WEEK AS THE RIDGING
WEAKENS AND SOUTHERLY FLOW ALOFT STRENGTHENS...HELPING INCREASE
THUNDERSTORM ACTIVITY WHILE ALSO ALLOWING FOR COOLER TEMPERATURES.
MINIMUM HUMIDITIES WILL GENERALLY REMAIN IN THE TEENS ACROSS THE
LOWER DESERTS...AND IN THE 20-30 PERCENT RANGE ACROSS THE HIGHER
TERRAIN...WITH GOOD TO EXCELLENT OVERNIGHT RECOVERIES THROUGH THE
PERIOD. WINDS TO REMAIN MAINLY ON THE LIGHT SIDE...WITH THE USUAL
DIURNAL TRENDS IN DIRECTION AND SPEED...EXCEPT NEAR THUNDERSTORMS.
$$
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...EXCESSIVE HEAT WARNING ACROSS THE SOUTH CENTRAL DESERTS...
AZZ022...AZ023...AZZ027...AZZ028...THROUGH 5 AM MONDAY.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...AJ
PREVIOUS DISCUSSION...VASQUEZ
AVIATION...AJ
FIRE WEATHER...CB/NOLTE
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NWS LOS ANGELES/OXNARD CA
1100 PM PDT SUN AUG 18 2013
.SYNOPSIS...
A SLIGHT CHANCE FOR THUNDERSTORMS ARE POSSIBLE IN THE SAN GABRIEL
MOUNTAINS AND ANTELOPE VALLEY AGAIN TOMORROW...WITH THE UPPER LOW
OFF THE CALIFORNIA COAST CONTINUING TO PULL SOME MONSOON MOISTURE
INTO THE AREA FROM THE SOUTHEAST. THE UPPER LOW WILL BEGIN TO LIFT
NORTHEAST ON THURSDAY...BUT WILL BE REPLACED BY ANOTHER TROUGH OF
LOW PRESSURE MOVING IN FROM THE NORTHWEST. THE RESULT WILL BE
CONTINUED NEAR OR SLIGHTLY BELOW NORMAL TEMPERATURES AND NIGHT
THROUGH MORNING LOW CLOUDS ALONG THE COAST.
&&
.SHORT TERM (TODAY-WED)...
A FEW VERY IMPRESSIVE THUNDERSTORMS DEVELOPED ACROSS THE NORTHEAST
PORTION OF LOS ANGELES COUNTY THIS AFTERNOON...MAINLY NORTH AND EAST
OF PALMDALE TODAY. A COUPLE STORM CELLS WERE RIGHT ON THE LOS
ANGELES...SAN BERNARDINO AND KERN COUNTY BORDER. CLOUD TOPS WERE AS
HIGH AS 45000 FT WITH VERY IMPRESSIVE RAIN AND HAIL CORES. LATEST
NWS RADAR WAS SHOWING MOST OF THE CONVECTIVE ACTIVITY OCCURRING IN
THE EASTERN PART OF SAN BERNARDINO COUNTY AND NORTH INTO KERN COUNTY
OVER THE LAST HOUR AND LIKELY SETTLING DOWN OVER OUR AREA. MANY
PARAMETERS CAME TOGETHER THIS AFTERNOON TO CAUSE THESE EXPLOSIVE
THUNDERSTORMS. ALTHOUGH PRECIPITABLE WATERS (PWAT) VALUES WERE NOT
THAT IMPRESSIVE AROUND 1.20" AND BEST MID LEVEL MOISTURE WAS ABOVE
600 MB (ABOVE 12000 FT). THE INSTABILITY LOOKED VERY IMPRESSIVE BY
MID MORNING AS RAP SOUNDINGS OVER THE MOUNTAINS INDICATED CAPE
VALUES WELL OVER 1000 J/KG. SINCE STORMS WERE ABLE TO
INITIATE...THEY HAD NO PROBLEM GROWING VERTICALLY. RADAR RETURNS
INDICATED VERY HIGH VIL (VERTICAL INTEGRATED LIQUID) AVAILABLE WITH
THE STORM WHICH WAS A GOOD REASON WHY THERE WAS NICKEL SIZE HAIL
REPORTED IN SOME HIGH DESERT LOCATIONS THIS AFTERNOON.
BY LOOKING AT THE WATER VAPOR IMAGERY...IT IS EASY TO SPOT THE
DIFFLUENT REGION OVER EASTERN LA COUNTY AND POINTS EAST AND NORTH
BASED ON WHERE THE UPPER LOW WAS SITUATED TO HELP LIFT THESE STORMS
AND EXPLODE LIKE THEY DID. THERE WAS AN IMPRESSIVE LANDSPOUT SPOTTED
NEAR HELENDALE WHICH IS NORTH OF VICTORVILLE IN SAN BERNARDINO
COUNTY. AS THE UPPER LOW BEGINS TO PIVOT FARTHER OFFSHORE THIS
EVENING...THERE LOOKS TO BE SOME POTENTIAL FOR A FEW NOCTURNAL
SHOWERS OVER THE COASTAL WATERS N OF POINT CONCEPTION. I DID ADD
SLIGHT CHANCE FOR THUNDERSTORMS FOR AREAS N OF POINT CONCEPTION FROM
THE COAST TO SLO INTERIOR VALLEYS AFTER MIDNIGHT THROUGH THE
OVERNIGHT HOURS...BUT NOT VERY CONFIDENT. AS FAR AS THE LOWER AND
MORE STABLE PART OF THE ATMOSPHERE...(THE MARINE LAYER) WAS AROUND
1000 FT DEEP EARLY THIS EVENING...WHICH IS A BIT DEEPER THEN LAST
NIGHT. WITH THE UPPER LOW JUST OFF THE CENTRAL COAST...THERE WILL BE
A SLIGHT DEEPENING OF THE MARINE LAYER WHICH WILL ALLOW FOR SOME LOW
CLOUDS TO CREEP INTO THE SAN GABRIEL AND POSSIBLY THE SAN FERNANDO
VALLEY AFTER MIDNIGHT. TODAY`S HIGH TEMPS WERE OVERALL A TAD
LOWER...BUT A FEW INTERIOR AREAS WERE AROUND THE SAME AS YESTERDAY.
LONG BEACH WAS MUCH COOLER TODAY AT ONLY 74 COMPARED TO 86 ON
SATURDAY DUE TO A PERSISTENT SOUTHERLY FLOW AND LOW CLOUDS HANGING
AROUND.
FOR MONDAY...NOT MUCH MOVEMENT IS EXPECTED WITH CUTOFF LOW...BUT
THERE WILL CONTINUE TO BE SOME MODEST MID LEVEL MOISTURE ADVECTING
NORTH OVER EASTERN LA COUNTY AND AREAS TO THE EAST. BOTH THE NAM-WRF
AND GFS ARE INDICATING MORE INSTABILITY OVER THE LA COUNTY
MOUNTAINS...HAVE ADDED A SLIGHT CHANCE OF THUNDERSTORMS FOR THE
EASTERN PORTION OF THE SAN GABRIEL VALLEY AND ANTELOPE VALLEY ONCE
AGAIN. THERE WILL BE LESS MOISTURE TO WORK WITH...BUT A SLIGHT
CHANCE SEEMS REASONABLE FOR TOMORROW AFTERNOON AND EARLY EVENING. AT
THE LEAST EXPECT PARTLY CLOUDY SKIES WITH SOME CUMULUS BUILDUPS IN
THE MOUNTAINS AND OVER THE ANTELOPE VALLEY. LOOK FOR A MODEST
COOLING TREND FOR TOMORROW AS THE UPPER RIDGE WEAKENS A
BIT...ESPECIALLY ACROSS THE NORTHERN PORTION OF THE FORECAST AREA N
OF POINT CONCEPTION. THERE WILL LIKELY BE SOME HIGH CLOUDS MOVING
TO THE NORTH ACROSS THE SKY...BUT WILL CONTINUE WITH MOSTLY SUNNY
SKIES. THE MID SHIFT CAN ADJUST IF NEED BE.
***FROM PREVIOUS DISCUSSION***
VERY LITTLE CHANGE TUE/WED. POSSIBLY SOME HIGH CLOUDS MOVING THROUGH
AT TIMES TUESDAY AS MOISTURE WRAPS AROUND THE STILL STATIONARY UPPER
LOW. BUT AT THIS TIME NOT SEEING ANYTHING TO WARRANT POPS OR EVEN
PARTLY CLOUDY SKIES. DAYTIME HIGHS EXPECTED TO CHANGE LITTLE.
.LONG TERM (THU-SUN)...UPPER LOW FINALLY EXITING THE STATE ON
THURSDAY TO BE REPLACED BY A WEAK TROF THROUGH THE WEEKEND. THE
ECMWF IS DEEPER WITH THE TROF AND THUS COOLER AS WELL. FOR NOW WILL
JUST INDICATE LITTLE CHANGE THROUGH THE PERIOD WITH HIGHS NEAR TO
SLIGHTLY BELOW SEASONAL NORMS. ALL MODEL SOLUTIONS KEEP MONSOON
MOISTURE WELL EAST INTO EARLY NEXT WEEK.
&&
.AVIATION...
19/0600Z.
VERY LOW CONFIDENCE FORECAST OVERNIGHT AS A GUST FRONT FROM THE
DESERT CONVECTION COULD WREAK HAVOC WITH THE MARINE LAYER. THERE IS
A SLIGHT CHC OF TSTMS OVER THE DESERT AND MTNS AS WELL AS ALL OF SLO
COUNTY OVERNIGHT.
KLAX...LOW CONFIDENCE IN TAF THERE IS A 30 PERCENT CHANCE OF A BRIEF
EAST WIND ALONG WITH A TOTAL DISRUPTION OF THE MARINE LAYER.
KBUR...LOW CONFIDENCE IN TAF THERE IS A 40 PERCENT CHANCE OF LIFR
CIGS 13Z-16Z.
&&
.FIRE...
A CUTOFF LOW PRESSURE SYSTEM OFF THE CENTRAL COAST WILL REMAIN
NEARLY STATIONARY THROUGH TUESDAY. THIS LOW PRESSURE SYSTEM IS
DRAWING SOME MOISTURE INTO SOUTHERN AND CENTRAL CALIFORNIA. AT THE
PRESENT TIME...THE MOISTURE AXIS IS FOCUSED ACROSS EASTERN LOS
ANGELES COUNTY AND POINTS EASTWARD. THIS INFLUX OF MOISTURE COMBINED
WITH AN UNSTABLE AIR MASS WILL CONTINUE TO GENERATE ISOLATED
THUNDERSTORMS ACROSS THE EASTERN PORTIONS OF THE SAN GABRIEL
MOUNTAINS AND ANTELOPE VALLEY THROUGH THIS EVENING. THESE STORMS
WILL HAVE THE POTENTIAL TO PRODUCE STRONG DOWNDRAFT
WINDS...HAIL...AND BRIEF HEAVY DOWNPOURS. AROUND THE PERIPHERY OF
STORMS...ISOLATED DRY LIGHTNING STRIKES WILL BE POSSIBLE. CLOSER TO
THE CLOSED LOW...THERE IS A VERY SLIGHT CHANCE OF STORMS TONIGHT
INTO MONDAY FOR AREAS NORTH OF POINT CONCEPTION.
THE LOW PRESSURE SYSTEM WILL BRING GUSTY SOUTHERLY WINDS TO INTERIOR
SECTIONS THROUGH MONDAY. WITH THE EXCEPTION OF EASTERN LOS ANGELES
COUNTY...REMAINING AREAS ARE FORECASTED TO BE QUITE DRY AT LOWER
ELEVATIONS. THIS COMBINATION OF GUSTY SOUTHERLY WINDS...LOW
HUMIDITIES...VERY WARM TEMPERATURES...AND VERY DRY FUELS WILL
CONTINUE TO BRING ELEVATED FIRE DANGER ACROSS INLAND AREAS THROUGH
MONDAY. BRIEF CRITICAL FIRE WEATHER CONDITIONS WILL BE LIKELY
THROUGH MONDAY ACROSS THE MOUNTAINS.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
PUBLIC...KAPLAN/MW
FIRE...GOMBERG
AVIATION...ASR
SYNOPSIS...SUKUP
WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
424 AM EDT MON AUG 19 2013
.SYNOPSIS...
A STATIONARY FRONT OVER THE AREA WILL DISSIPATE AS HIGH PRESSURE
BUILDS WEST ACROSS THE AREA MID TO LATE WEEK. A WEAK TROUGH OF LOW
PRESSURE WILL APPROACH FROM THE NORTHWEST THIS WEEKEND...FOLLOWED BY
HIGH PRESSURE INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
PRE-DAWN...A MOIST AND RELATIVELY UNSTABLE AIR MASS ACROSS THE REGION
EARLY THIS MORNING...QUITE TYPICAL FOR THE SEASON. THROUGH DAWN...MOST
AREAS SHOULD REMAIN DRY WITH A FEW SHOWERS POSSIBLE NEAR/ALONG THE
COAST AND ADJACENT TO THE CSRA AREA PRIOR TO DAYBREAK. TEMPS AND DEW
POINTS IN THE MID 70S MOST AREAS.
SOUTHEAST GEORGIA AND SOUTHERN SOUTH CAROLINA WILL REMAIN IN THE
NW FLANKS OF THE ATLC SUBTROPICAL RIDGE TODAY. THE DEPARTING UPPER
TROUGH FROM THE OHIO VALLEY TO THE MID SOUTH REGION IS PROGGED TO
LIFT OUT TO THE NE INTO NEW ENGLAND BY LATE DAY. THE TAIL OF THE MID
LEVEL VORT WILL INDUCE SOME VERY WEAK HEIGHT FALLS OVER THE INLAND
CAROLINAS TODAY WHILE DEEP MID SUMMER MOISTURE PERSISTS REGION-WIDE.
THE OLD WEDGE FRONT CONTINUES TO DECAY OVER THE CAROLINAS TODAY.
FORECAST SOUNDINGS AND 00Z MODEL PROGS INDICATE POTENTIAL FOR
SCATTERED CONVECTIVE RAINS TO DEVELOP OVER THE EASTERN THIRD OF
THE AREA BY MID MORNING ONCE THE LAND MASS BEGINS TO QUICKLY WARM
AND ESPECIALLY SINCE SATELLITE IMAGERY SHOWS STRONG POTENTIAL FOR
DIFFERENTIAL HEATING WITH I-95 THE DIVIDING LINE. CHANCE POPS ARE
EXPECTED TO SPREAD INLAND THIS AFTERNOON WITH MANY AREAS ALONG AND
W OF U.S. 17 EXPECTED TO SEE SCATTERED SHOWERS AND TSTMS. SOME OF
OUR INLAND AREAS COULD SEE SOME VERY HEAVY DOWNPOURS IN DEEP
CONVECTION THIS AFTERNOON. THE LATEST 3KM RAP MODEL INDICATES A
PRETTY COMPLEX MESOSCALE AND THUS EXPECT SOME LOCALLY HEAVY
CONVECTIVE RAINS WILL DEVELOP N OF I-16 AND INLAND FROM U.S. 17
WHERE THE SUBTLE MID LEVEL HEIGHT FALLS OCCUR. WE WILL HIGHLIGHT A
RISK FOR LOCALLY HEAVY DOWNPOURS AND MINOR TEMPORARY FLOODING
CONCERNS FOR OUR NW INLAND ZONES IN OUR HAZARDOUS WEATHER OUTLOOK.
THIS IS MAINLY IN RESPECT TO THE SOGGY SOIL CONDITIONS AND ONGOING
RIVER FLOODING PLUS SWOLLEN TIDAL CREEKS WITH THE FULL MOON CYCLE.
WE RAISED HIGH TEMPS A DEGREE OR SO IN SOME AREAS AS GUIDANCE IS
RUNNING TOO COOL NOW THE WEDGE TO GONE.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
TUESDAY THROUGH THURSDAY...A TYPICAL SUMMERTIME PATTERN WILL EVOLVE
OVER THE SOUTHEASTERN UNITED STATES AS ATLANTIC HIGH PRESSURE
EXPANDS OVER THE AREA THROUGH MIDWEEK. AS THIS OCCURS...DEEPEST
MOISTURE WILL SHIFT INLAND AND WILL BE THE MAIN SOURCE OF PRECIP
ACTIVITY EACH AFTERNOON WHILE WEAK H5 SHORTWAVES PASS OVERHEAD.
DESPITE THE INLAND SHIFT OF DEEPEST MOISTURE...LIGHT ONSHORE FLOW
WILL SUPPORT PWATS BETWEEN 1.5 TO 2 INCHES AS WELL AS SCATTERED
SHOWERS AND/OR THUNDERSTORMS OVER SOUTHEAST SOUTH CAROLINA AND
SOUTHEAST GEORGIA. HOWEVER...EXPECT MOST SHOWERS/THUNDERSTORMS TO
GRADUALLY SHIFT INLAND BY EARLY AFTERNOON EACH DAY ALONG OR AHEAD A
SEABREEZE.
OVERALL HIGH TEMPS SHOULD RANGE IN THE UPPER 80S TO AROUND 90 EACH
AFTERNOON. OVERNIGHT LOWS WILL RANGE IN THE LOW 70S INLAND TO
MID/UPPER 70S ALONG THE COAST.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
A TYPICAL SUMMERTIME PATTERN WILL PERSIST THROUGH LATE WEEK AS
ATLANTIC HIGH PRESSURE REMAINS OVER THE SOUTHEAST. CONDITIONS SHOULD
REMAIN SOMEWHAT DRYER THROUGH FRIDAY WITH WEST/SOUTHWEST FLOW ALOFT.
HIGH PRESSURE WILL THEN GRADUALLY RETREAT SOUTH AND EAST INTO THE
WEEKEND AS A WEAK TROUGH OF LOW PRESSURE APPROACHES FROM THE
NORTHWEST. A SLIGHT CHANCE OF SHOWERS AND/OR THUNDERSTORMS WILL BE
POSSIBLE EACH DAY...WITH POSSIBLY INCREASING CHANCES ON SUNDAY
BEFORE SFC HIGH PRESSURE AND DRYER MID LVL AIR SHIFTS OVER THE
SOUTHEAST INTO EARLY NEXT WEEK. OVERALL HIGH TEMPS SHOULD RANGE IN THE
UPPER 80S TO LOWER 90S EACH AFTERNOON...HIGHEST OVER INLAND AREAS IN
SOUTHEAST GEORGIA. OVERNIGHT LOW TEMPS SHOULD RANGE IN THE LOW 70S
INLAND TO LOW/MID 70S ALONG THE COAST.
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
A MAINLY VFR FORECAST THIS TAF CYCLE AT THE KCHS/KSAV TERMINALS
WITH POTENTIAL FOR BRIEF MVFR CIGS JUST AFTER SUNRISE AS THE LAND
HEATS AND CUMULUS FIELDS DEVELOP. SCATTERED SHOWERS DEVELOPING
THIS MORNING IN THE COASTAL CORRIDOR PER LATEST MODEL OUTPUT...
PUSHING INLAND THIS AFTERNOON. IF DEEPER CONVECTION DEVELOPS IT
COULD SLIDE BACK INTO THE THE TAF CORRIDOR AFTER MID AFTERNOON
AS STEERING FAVORS A SW-NE TRAJECTORY. VCSH THE BEST WE DO FOR
NOW...SIMILAR TO THE LAST PACKAGE.
EXTENDED AVIATION OUTLOOK...VFR CONDITIONS ARE EXPECTED TO PREVAIL
TUESDAY THROUGH SATURDAY AS HIGH PRESSURE PERSISTS OVER THE
SOUTHEAST. BRIEF MVFR CIGS/VSBYS ARE POSSIBLE EACH AFTERNOON WITH
INLAND MOVING SHOWERS AND/OR THUNDERSTORMS.
&&
.MARINE...
ATLC HIGH PRES WILL BE THE MAIN PLAYER FOR THE WATERS. MAINLY A
LIGHT SE TO SSE FLOW THROUGH TONIGHT WITH SEAS 2 TO 3 FT.
TUESDAY THROUGH FRIDAY...WINDS/SEAS ARE EXPECTED TO REMAIN WELL
BELOW SMALL CRAFT ADVISORY LEVELS THROUGH LATE WEEK WITH HIGH
PRESSURE DOMINATING THE WATERS. IN GENERAL...SOUTH TO SOUTHEAST
WINDS WILL REMAIN AT OR BELOW 10-12 KT...HIGHEST NEAR SEABREEZE
CIRCULATIONS ALONG THE COAST. SEAS WILL REMAIN AT OR BELOW
3 FT...HIGHEST IN OUTER GEORGIA WATERS.
WATERSPOUTS...IT IS LOOKING DECENT THIS MORNING GIVEN INSTABILITY
AND LIGHT CHAOTIC WIND FIELDS. WILL BE WAITING FOR SUNRISE TO SPOT
CU LINES AND LAND BREEZE BOUNDARIES BEFORE ISSUING ANY MARINE WEATHER
STATEMENTS.
RIP CURRENTS...A SLIGHT INCREASE IN SWELLS COULD LEAD TO A MODERATE
RISK OF RIPS BY MID WEEK. LOW RISK AT AREA BEACHES TODAY.
&&
.TIDES/COASTAL FLOODING...
GIVEN THE PERIGEAN SPRING TIDES...ADDITIONAL COASTAL FLOOD
ADVISORIES ARE POSSIBLE THROUGH MID-WEEK WITH THE EVENING HIGH
TIDE CYCLE. THIS EVENINGS HIGH TIDE SHORTLY BEFORE SUNSET COULD
PRODUCE SHALLOW COASTAL FLOODING IN DOWNTOWN CHARLESTON AND FORT
PULASKI ONCE AGAIN.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...DPB
LONG TERM...DPB
AVIATION...
MARINE...DPB
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
149 AM EDT MON AUG 19 2013
.UPDATE...
/ISSUED AT 940 PM EDT SUN AUG 18 2013/
HAVE ADJUSTED POPS FOR A FEW HOURS BASED ON RADAR. SCATTERED
CONVECTION STILL MOSTLY ACROSS CENTRAL ZONES. WEDGE STILL HOLDING
JUST ABOUT ATLANTA TO ATHENS AND MAY NOT MUCH MUCH MORE OVERNIGHT.
WILL KEEP THE FLASH FLOOD WATCH UNTIL EXPIRATION.
41
.PREVIOUS...
/ISSUED AT 250 PM EDT SUN AUG 18 2013/
.SHORT TERM /TONIGHT THROUGH MONDAY/...
PRIMARY CONCERNS FOR THE SHORT TERM PERIOD WILL BE WHERE MODERATE
TO HEAVY RAIN AXIS SETS UP AND WHAT NEEDS TO BE DONE WITH THE
FLASH FLOOD WATCH AS A RESULT. AFTER A WET START TO THE
DAY...ACTIVITY HAS DWINDLED FOR THE MOST PART WITH JUST SOME
PASSING SHOWERS THROUGH THE ATLANTA METRO NOW HEADING INTO
NORTHEAST GEORGIA. FOCUS NOW SHIFTS TO THE SOUTHEAST WHERE LOCAL
WRF AND HRRR HAVE BEEN BEEN HONING IN ON WITH THUNDERSTORMS
DEVELOPING NICELY OVER THE FAR SOUTHEAST AT THIS HOUR. SPC SREF
SHOWS INSTABILITY INCREASING AS WARM FRONT EASES NORTHWARD WITH
AREAS AROUND TOOMBS AND MONTGOMERY COUNTIES SHOWING IN EXCESS OF
1000 J/KG OF AVAILABLE CAPE. WOULD EXPECT A LINE OF SHOWERS AND
STORMS TO DEVELOP IN THIS AREA AND PROGRESS TOWARD MACON LATER THIS
AFTERNOON INTO THE EVENING. ADDITIONAL ACTIVITY COULD FORM AHEAD
OF THIS AS WELL IN THE MORE UNSTABLE SECTION FROM COLUMBUS TO JUST
SOUTH OF ATHENS.
ALSO WATCHING GULF INITIATED STORMS AS THESE LOOK TO AFFECT THE
SOUTH AS WELL TONIGHT WITH STORMS ALREADY PUSHING INTO THE GEORGIA
PORTION FROM THE FLORIDA PANHANDLE. THERE IS SOME DISPARITY IN
SHORT TERM MODELS ON HOW THIS WILL EVENTUALLY EVOLVE THIS EVENING
WITH NAM12 INDICATING MORE DEVELOPMENT ON THE WESTERN SIDE OF THE
AREA VERSUS THE SOUTH. THIS UNCERTAINTY IS PROBLEMATIC GIVEN THE
FLOOD WATCH ORIENTATION WHICH IS CURRENTLY OVER THE WEST. IF
CURRENT TRENDS HOLD HOWEVER...THE SOUTHERN SECTIONS WOULD BE MORE
UNDER THE GUN. WITH THE UNCERTAINTY INVOLVED...WILL LET THE
EVENING SHIFT TAKE ANOTHER LOOK AT THIS DEVELOPING EVENT TO SEE
IF FLOOD WATCH NEEDS TO CONTINUE AND FOR WHAT AREAS.
FOR MONDAY...PRETTY MUCH THE SAME PATTERN BUT WITH WEDGE
CONTINUING TO WEAKEN AND MORE MOISTURE AVAILABLE FOR THE NORTHERN
ZONES AS WELL AS INSTABILITY. WENT LIKELY FOR MOST
AREAS...FAVORING THE SOUTH ONCE AGAIN...CLOSER TO THE VICINITY OF
STALLED OUT BOUNDARY. STILL USED SOME SLIGHT CAD INFLUENCES FOR
THE HIGH TEMPS MONDAY BUT SHOULD WARM NICELY TO UPPER 70S NORTH TO
LOWER 80S SOUTH.
DEESE
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
/ISSUED AT 250 PM EDT SUN AUG 18 2013/
BUMPED POPS UP SOME INTO THURSDAY TO ACCOUNT FOR THE VERY MOIST
AIRMASS OVER THE AREA. OTHERWISE NO MAJOR CHANGES.
BDL
PREVIOUS DISCUSSION...
THE WET PATTERN CONTINUES INTO THE EXTENDED. THE STATIONARY FRONT
OVER SOUTH GA TODAY WILL MOVE SLOWLY NORTHWARD THROUGH MONDAY AND
SHOULD BE SOME WHERE BETWEEN ATL AND MCN BY TUE MORNING. THIS FRONT
WILL WEAKEN SOME BUT IT WILL STILL ACT AS A GUIDE FOR GULF MOISTURE
TO MOVE NORTHWARD ACROSS THE REGION THROUGH THE MIDDLE OF THE WEEK.
THE WEDGE LOOKS TO FINALLY BREAK DOWN SOMETIME MONDAY WHICH WILL
ALSO ALLOW FOR A MORE DIURNALLY DRIVEN PRECIP PATTERN THROUGH DAY 7.
BEST TIMING FOR THE HEAVIEST RAIN WILL BE IN THE SHORT TERM BUT DEEP
TROPICAL MOISTURE REMAINS OVER THE REGION THROUGH WED/THU WITH
PRECIPITABLE WATERS IN THE 1.5 TO 2.0 INCH RANGE THROUGH THU. THE
DEEPER MOISTURE MOVES NORTH AND EAST OF THE STATE BY THU NIGHT BUT
THE DIURNAL CONVECTIVE TREND WILL CONTINUE INTO NEXT WEEKEND. TEMPS
WILL BEGIN TO REBOUND BY TUE AND BE BACK TO NEAR SEASONAL NORMS BY
THU/FRI.
01
&&
.AVIATION...
06Z UPDATE...
FRONTAL BOUNDARY JUST SOUTH OF ATL SHOULD REMAIN THERE TONIGHT...
THEN DRIFT NORTH OF ATL MON AFTERNOON. LIGHT EAST WINDS WILL PERSIST
TONIGHT...THEN BECOME MORE SE BY MON AFTERNOON AT 7-9KTS. EXPECT
IFR/LIFR CIGS TO PREVAIL AGAIN TONIGHT WITH -DZ/BR RESTRICTING VSBY
DOWN TO 1-3SM AT TIMES. CIGS GRADUALLY IMPROVE TO MVFR BY 15Z...THEN
POSSIBLY LOW VFR LEVELS BY 17-19Z MON AS THE WARM FRONT DRIFTS
NORTH. MODELS SHOW SCT -SHRA/-TSRA AROUND BY MON AFTERNOON SO WILL
INCLUDE A PROB30 -TSRA 20-24Z MON AS ATL GETS IN THE WARM SECTOR.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM ON ALL ELEMENTS
39
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 69 81 69 79 / 50 60 50 70
ATLANTA 69 79 70 79 / 70 50 40 60
BLAIRSVILLE 65 76 66 78 / 70 50 50 60
CARTERSVILLE 69 79 69 78 / 70 50 50 60
COLUMBUS 71 83 72 85 / 50 60 40 70
GAINESVILLE 68 78 69 76 / 70 50 50 70
MACON 70 82 70 82 / 40 60 40 60
ROME 69 80 70 80 / 70 50 50 60
PEACHTREE CITY 70 80 71 79 / 60 50 40 60
VIDALIA 72 86 72 86 / 40 60 40 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING
ZONES: BARTOW...BIBB...BLECKLEY...BUTTS...CARROLL...CATOOSA...
CHATTAHOOCHEE...CHATTOOGA...CHEROKEE...CLAYTON...COBB...COWETA...
CRAWFORD...CRISP...DADE...DEKALB...DODGE...DOOLY...DOUGLAS...
FANNIN...FAYETTE...FLOYD...GILMER...GORDON...HARALSON...HARRIS...
HEARD...HENRY...HOUSTON...LAMAR...MACON...MARION...MERIWETHER...
MONROE...MURRAY...MUSCOGEE...NORTH FULTON...PAULDING...PEACH...
PICKENS...PIKE...POLK...PULASKI...ROCKDALE...SCHLEY...SOUTH
FULTON...SPALDING...STEWART...SUMTER...TALBOT...TAYLOR...
TELFAIR...TROUP...TWIGGS...UPSON...WALKER...WEBSTER...
WHITFIELD...WILCOX.
&&
$$
SHORT TERM...DEESE
LONG TERM....BDL
AVIATION...39
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
535 AM EDT Mon Aug 19 2013
...Forecast Update...
Issued at 530 AM EDT Mon Aug 19 2013
Updated the forecast to remove areas of fog with patchy dense fog
from southeast Indiana and the Bluegrass region of KY. Mid level
clouds and lesser low level moisture than central and southern KY
(where patches of dense fog have been reported) have limited fog
formation over southeast Indiana and the Bluegrass. Downgraded this
area to just patchy fog for the rest of the pre-dawn hours.
Issued an SPS for portions of south and central KY where patchy
dense fog has been reported and where it rained yesterday (which
should be fog prone). Few-sct mid level clouds continue to move
over this area improving fog at times so feel dense fog coverage
will remain patchy.
.SHORT TERM (Now through Tuesday)...
Issued at 330 AM EDT Mon Aug 19 2013
The main forecast concern in the short term will be fog this
morning. A very moist low level atmosphere along with very light or
nearly calm winds have created an ideal environment for fog
formation which we`ve already seen develop in our area. The worst
fog spots remain over southern IL/western KY and over southwest
Ohio. The 5Z RAP model has these fog areas handled well and expect
them to expand into central KY and portions of southeast IN. Low
clouds will also accompany the fog as soundings indicate a shallow
layer of trapped moisture under a weak inversion. With these
thoughts in mind, think that most locations over southern IN and
central KY will see areas of fog this morning. Some locations over
central KY and southeast IN will probably see patches of dense fog
as well assuming the low clouds don`t inhibit fog density too much.
Will highlight the patchy dense fog in the HWO this morning and
monitor closely in case it becomes more widespread and an SPS or
dense fog advisory is need.
For the rest of the day, fog should burn off fairly quickly after
sunrise. With an upper trough passing through the region, can`t
rule out an isld shower over portions of south and east central KY.
However, did scale the area of potential precip back a bit. High
temperatures should reach the low to mid 80s this afternoon.
Tonight a second upper trough will settle into the mid Mississippi
River Valley. Some fog may be possible but not as widespread as
this morning. Will continue inherited patchy fog mainly in river
valleys. Lows tonight will be in the mid 60s.
For Tues, expect a 20% chance of showers/t-storms to expand from
south to north over the area throughout the day as a vort wave on
the eastern side of the upper trough push north through our area.
Any convection would be on the weak side. Tuesday afternoon high
temps should be in the low to mid 80s with southern Indiana being
the hottest due to a longer period of sunshine before clouds/isld
convection move in.
.LONG TERM (Tuesday Night through Sunday)...
Issued at 311 AM EDT Mon Aug 19 2013
The models have finally come into agreement with a mid-level low
that forms over the Ohio Valley at the start of this forecast
period. This cutoff low hangs out in the region through Thursday
night when it undergoes a transformation into an open wave in
response to an approaching shortwave. This shortwave rides around
the periphery of a stout ridge building in over the Plains and looks
to exit the forecast area by early Saturday. The ridge continues to
build in from the west, giving us dry conditions through the end of
the weekend and into early next week.
Tuesday night through Thursday:
For this issuance, have introduced slight chance PoPs for Tuesday
night as the low establishes itself overhead and surface southerly
flow allows for moisture to be pulled in. Chance PoPs continues for
Wednesday as daytime heating assists in convection across the area.
With the loss of daytime heating and in conjunction with general
model consensus, have kept PoPs out overnight Wednesday into early
Thursday. As the low is depicted to begin traversing eastward
Thursday, have only slight chance during the day with the primary
focus for possible convection more toward eastern KY. The models
have the low slowly but surely progressing eastward during this time
frame and am a little skeptical on its speed. How quickly the low
exits will depend on the timing of a weak frontal boundary
attempting to lay out across the southern Great Lakes by Thursday
night.
Thursday night through Friday night:
Have gone with slight chance PoPs strictly across the northern
sections as the alluded to frontal boundary approaches from the
north. The front stalls well to our north and does not currently
appear to be a factor for us beyond Friday. The aforementioned
shortwave swings around the region Friday, hence the slight to
chance PoPs under diurnally-driven conditions. Again, skepticism
sets in for the timing of it all as it seems to really move through
a little too quickly. For now, have kept the area dry Friday night
until a better handle on the progression of everything plays out.
Temperatures will be more difficult to predict Tuesday night through
Friday night as cloudy skies and/or rain will obviously wreck havoc.
What can be said with confidence is that highs will continue to run
slightly below normal and lows will flirt with normal.
Saturday through Sunday:
With that ridge building in, we`ll begin to see real signs of summer
return as temperatures look to rebound back toward normal and partly
to mostly sunny skies prevail.
&&
.AVIATION (06Z TAF Update)...
Issued at 125 AM EDT Mon Aug 19 2013
The TAF challenge this morning will be the extent and intensity of
fog and low cigs over the TAF sites as we sit in a very moist
environment with weak or calm winds. Observations across the region
reveal 2 areas of fog/low cigs...one over Illinois/western KY and
the other over southwest Ohio. The RAP is picking up on these areas
of fog/low cigs well and forecasts that they will expand into
SDF/BWG/LEX as the morning progresses. LEX seems to be the most
likely to see the worst flight conditions with MVFR conditions
likely to develop within the next few hours and decline to LIFR by
around 9 or 10Z. BWG/SDF seem to be more on the edges of the
projected fog/low cigs. Since BWG is very fog prone, did go ahead
and bring flight conditions into the LIFR cat by 9Z with a slightly
slower progression to that restriction than LEX. SDF seems to be
the least likely to see really low vsbys/cigs although based on the
latest RAP guidance, they will probably drop into the IFR cat just
before sunrise. If the fog/low cigs expand more than projected by
the RAP, SDF TAF will need to be amended with more flight
restrictions.
Fog/low cigs should improve by 13 or 14Z with VFR conditions
expected the rest of the day with a light ENE wind.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........AMS
Short Term.....AMS
Long Term......lg
Aviation.......AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
333 AM EDT Mon Aug 19 2013
.SHORT TERM (Now through Tuesday)...
Issued at 330 AM EDT Mon Aug 19 2013
The main forecast concern in the short term will be fog this
morning. A very moist low level atmosphere along with very light or
nearly calm winds have created an ideal environment for fog
formation which we`ve already seen develop in our area. The worst
fog spots remain over southern IL/western KY and over southwest
Ohio. The 5Z RAP model has these fog areas handled well and expect
them to expand into central KY and portions of southeast IN. Low
clouds will also accompany the fog as soundings indicate a shallow
layer of trapped moisture under a weak inversion. With these
thoughts in mind, think that most locations over southern IN and
central KY will see areas of fog this morning. Some locations over
central KY and southeast IN will probably see patches of dense fog
as well assuming the low clouds don`t inhibit fog density too much.
Will highlight the patchy dense fog in the HWO this morning and
monitor closely in case it becomes more widespread and an SPS or
dense fog advisory is need.
For the rest of the day, fog should burn off fairly quickly after
sunrise. With an upper trough passing through the region, can`t
rule out an isld shower over portions of south and east central KY.
However, did scale the area of potential precip back a bit. High
temperatures should reach the low to mid 80s this afternoon.
Tonight a second upper trough will settle into the mid Mississippi
River Valley. Some fog may be possible but not as widespread as
this morning. Will continue inherited patchy fog mainly in river
valleys. Lows tonight will be in the mid 60s.
For Tues, expect a 20% chance of showers/t-storms to expand from
south to north over the area throughout the day as a vort wave on
the eastern side of the upper trough push north through our area.
Any convection would be on the weak side. Tuesday afternoon high
temps should be in the low to mid 80s with southern Indiana being
the hottest due to a longer period of sunshine before clouds/isld
convection move in.
.LONG TERM (Tuesday Night through Sunday)...
Issued at 311 AM EDT Mon Aug 19 2013
The models have finally come into agreement with a mid-level low
that forms over the Ohio Valley at the start of this forecast
period. This cutoff low hangs out in the region through Thursday
night when it undergoes a transformation into an open wave in
response to an approaching shortwave. This shortwave rides around
the periphery of a stout ridge building in over the Plains and looks
to exit the forecast area by early Saturday. The ridge continues to
build in from the west, giving us dry conditions through the end of
the weekend and into early next week.
Tuesday night through Thursday:
For this issuance, have introduced slight chance PoPs for Tuesday
night as the low establishes itself overhead and surface southerly
flow allows for moisture to be pulled in. Chance PoPs continues for
Wednesday as daytime heating assists in convection across the area.
With the loss of daytime heating and in conjunction with general
model consensus, have kept PoPs out overnight Wednesday into early
Thursday. As the low is depicted to begin traversing eastward
Thursday, have only slight chance during the day with the primary
focus for possible convection more toward eastern KY. The models
have the low slowly but surely progressing eastward during this time
frame and am a little skeptical on its speed. How quickly the low
exits will depend on the timing of a weak frontal boundary
attempting to lay out across the southern Great Lakes by Thursday
night.
Thursday night through Friday night:
Have gone with slight chance PoPs strictly across the northern
sections as the alluded to frontal boundary approaches from the
north. The front stalls well to our north and does not currently
appear to be a factor for us beyond Friday. The aforementioned
shortwave swings around the region Friday, hence the slight to
chance PoPs under diurnally-driven conditions. Again, skepticism
sets in for the timing of it all as it seems to really move through
a little too quickly. For now, have kept the area dry Friday night
until a better handle on the progression of everything plays out.
Temperatures will be more difficult to predict Tuesday night through
Friday night as cloudy skies and/or rain will obviously wreck havoc.
What can be said with confidence is that highs will continue to run
slightly below normal and lows will flirt with normal.
Saturday through Sunday:
With that ridge building in, we`ll begin to see real signs of summer
return as temperatures look to rebound back toward normal and partly
to mostly sunny skies prevail.
&&
.AVIATION (06Z TAF Update)...
Issued at 125 AM EDT Mon Aug 19 2013
The TAF challenge this morning will be the extent and intensity of
fog and low cigs over the TAF sites as we sit in a very moist
environment with weak or calm winds. Observations across the region
reveal 2 areas of fog/low cigs...one over Illinois/western KY and
the other over southwest Ohio. The RAP is picking up on these areas
of fog/low cigs well and forecasts that they will expand into
SDF/BWG/LEX as the morning progresses. LEX seems to be the most
likely to see the worst flight conditions with MVFR conditions
likely to develop within the next few hours and decline to LIFR by
around 9 or 10Z. BWG/SDF seem to be more on the edges of the
projected fog/low cigs. Since BWG is very fog prone, did go ahead
and bring flight conditions into the LIFR cat by 9Z with a slightly
slower progression to that restriction than LEX. SDF seems to be
the least likely to see really low vsbys/cigs although based on the
latest RAP guidance, they will probably drop into the IFR cat just
before sunrise. If the fog/low cigs expand more than projected by
the RAP, SDF TAF will need to be amended with more flight
restrictions.
Fog/low cigs should improve by 13 or 14Z with VFR conditions
expected the rest of the day with a light ENE wind.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Short Term........AMS
Long Term.........lg
Aviation..........AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
152 AM EDT Mon Aug 19 2013
...Forecast Update...
Issued at 145 AM EDT Mon Aug 19 2013
Updated to remove isld POPs over south and east central KY. Looks
like the stream of moisture/forcing for those light precip chances
has moved mostly to our east.
The main forecast challenge for this morning will be fog and low
clouds. The latest RAP model has the best handle on fog/low cloud
areas developing over southern IL/western KY and southwest OH this
morning. It projects those areas will expand into much of central
KY and southeast IN. Current forecast handles the areal extent of
fog well, but a mention of patchy dense fog may be needed with the
4am forecast package. Low clouds would be the main inhibitor of
dense fog but even so, the model indicates visibilities should drop
below a half mile. For now will hold off on a dense fog mention,
and watch fog/low cloud development over the next few hours.
Issued at 1140 PM EDT Sun Aug 18 2013
One more update to bump up coverage of fog some. Seeing visibilities
drop in a few spots late this evening. The clear spot to our west
has seen PAH drop down to a quarter mile in its latest ob. Will have
to watch for worse visibilities over our area tonight, but for now
the trend looks good. Still cannot rule out a stray shower
developing, as the upper trough axis still has not passed our
region. Have left in a slight chance across the southeast for a few
more hours tonight.
Issued at 625 PM EDT Sun Aug 18 2013
Active convection appears confined to a line running from north of
Hartford to west of Lawrenceburg in KY. Fine tuned the rain chances
to focus on this region next couple of hours. Still expect activity
to quiet down with loss of heating and as the upper low, which has
been near us for days, weakens and accelerates northeast.
Next issue will be the chance for fog. Statistical guidance hints at
visibilities lowering during the night, and this makes sense with
residual moisture. Cloud cover should keep us from going too dense
however. For now have added in patchy fog everywhere after midnight.
.SHORT TERM (Now through Monday Night)...
Issued at 300 PM EDT Sun Aug 18 2013
The cutoff upper low that was centered over the Mississippi and Ohio
River confluence this morning is filling, becoming an open wave, and
meandering eastward, as another shortwave trough begins to dive
southeast into the upper Mississippi Valley. Scattered showers and
isolated storms will be possible through the afternoon and early
evening hours, as heating combines with large-scale ascent. The
mid-level trough axis will swing across the area tonight, combined
with loss of heating, will put an end to convection. So, will have
scattered precipitation tapering off from west to east through the
evening hours, with a dry forecast from about midnight onward.
Will continue with dry conditions through Monday morning. However,
the trough across the upper Mississippi Valley tonight will spread
across the Ohio Valley by Monday afternoon. Appears some low-level
moisture will remain in place and with afternoon heating, could
spark some convection. Soundings indicate there should be slight
capping across much of the CWA, allowing mainly low-topped showers
to develop. By late in the afternoon the cap could weaken just
enough to squeeze out an isolated thunderstorm or two, but that
chance appears minimal. So, will run with isolated showers in the
forecast through the afternoon and early evening hours Monday. This
will generally be along and southeast of a line from Frankfort
southwestward to Bowling Green. Any activity will dissipate with
loss of heating, leaving the overnight hours dry.
Temperatures will drop into the lower 60s tonight, with a few breaks
in the cloud cover. Highs in the low to middle 80s will be common
Monday under partly cloudy skies. Expect lows in the low and middle
60s Monday night under partly cloudy to mostly clear skies. Cannot
rule out some patchy fog tonight and Monday night, but tonight will
depend on how much cloud cover is lost and Monday night will depend
on how much drying occurs through Monday afternoon.
.LONG TERM (Tuesday through Sunday)...
Issued at 300 PM EDT Sun Aug 18 2013
The long term period continues to look rather unsettled for much of
the upcoming work week as the Ohio Valley will remain in a rather
stagnant upper level pattern. However, the overall pattern looks to
improve a bit by the end of the week and into the weekend as the
latest forecast datasets point to upper level ridging building in
from the west which will result in warmer and more seasonal
temperatures for the region.
Until late week, the upper level flow is forecast to remain rather
blocky and complex as the band of westerlies remains holed up along
the US/Canadian border. Overall, there is not much forcing in the
hemispheric flow to kick things into gear and smooth the wave
pattern out. With that said, the model solutions show that a
bagging long wave trough axis will remain over the eastern part of
the US from Tuesday through at least late Thursday. With the trough
axis overhead, diurnally driven convection will be possible across
the region. While the overall coverage for the week looks to be
isolated to scattered, it does appear that the best chances for
rainfall would be Wednesday as the actual trough pulls through the
region. With this forecast we plan on keeping isolated-scattered
PoPs in the forecast each afternoon for Tuesday-Thursday with the
highest chances Wednesday. With regards to convection strength, the
combination of weak flow aloft and rather modest instability
suggests that severe weather is not likely. However, high
atmospheric moisture content combined with the weak steering flow
could lead to heavy rain production with any storm that develops.
Temperatures through the period will remain below normal. Have
sided again with the consensus raw datasets for max/min temperatures
as they have verified well over the last few days. This actually
results in a cooling trend applied for Tuesday/Wednesday due to
expected clouds and precipitation. Tues/Wed highs will average in
the lower 80s across the central/east/southeast with lower-middle
80s across the northwest/west sections. With the upper trough
passing to our east on Thursday, we expect less clouds and
precipitation which should allow temperatures to warm into the
middle 80s. Overnight lows will be rather mild with readings in the
upper 60s to the lower 70s.
By Friday, the model solutions start to show their normal spread.
The GFS solutions suggest a weak cold front will pass through the
region and then stall out to our south. On the other hand, the Euro
solution is not as progressive and allow the upper ridging to build
in which would keep the frontal boundary up to our north. For now
have, opted to keep the forecast on the dry side, but will continue
to monitor later forecasts to see if PoPs will be required. With the
upper ridge building in, Sat/Sun continue to look dry at this point.
Temperatures should continue to moderate through the period with
afternoon highs in the middle to upper 80s with overnight lows in
the upper 60s to the lower 70s.
&&
.AVIATION (06Z TAF Update)...
Issued at 125 AM EDT Mon Aug 19 2013
The TAF challenge this morning will be the extent and intensity of
fog and low cigs over the TAF sites as we sit in a very moist
environment with weak or calm winds. Observations across the region
reveal 2 areas of fog/low cigs...one over Illinois/western KY and
the other over southwest Ohio. The RAP is picking up on these areas
of fog/low cigs well and forecasts that they will expand into
SDF/BWG/LEX as the morning progresses. LEX seems to be the most
likely to see the worst flight conditions with MVFR conditions
likely to develop within the next few hours and decline to LIFR by
around 9 or 10Z. BWG/SDF seem to be more on the edges of the
projected fog/low cigs. Since BWG is very fog prone, did go ahead
and bring flight conditions into the LIFR cat by 9Z with a slightly
slower progression to that restriction than LEX. SDF seems to be
the least likely to see really low vsbys/cigs although based on the
latest RAP guidance, they will probably drop into the IFR cat just
before sunrise. If the fog/low cigs expand more than projected by
the RAP, SDF TAF will need to be amended with more flight
restrictions.
Fog/low cigs should improve by 13 or 14Z with VFR conditions
expected the rest of the day with a light ENE wind.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........AMS/RJS
Short Term.....MJP
Long Term......MJ
Aviation.......AMS
AREA FORECAST DISCUSSION
NWS JACKSON KY
137 AM EDT MON AUG 19 2013
.UPDATE...
ISSUED AT 137 AM EDT MON AUG 19 2013
FORECAST PRETTY MUCH ON TRACK SO FAR TONIGHT. A LINE OF RAIN SHOWERS
CURRENTLY MOVING UP THE VIRGINIA AND WEST VIRGINIA BORDERS TONIGHT
ARE CONTINUING TO SPREAD EVER SO SLOWLY WESTWARD INTO FAR EASTERN
KENTUCKY. THIS EVOLUTION IS EXPECTED TO CONTINUE OVERNIGHT AND DURING
THE DAY ON MONDAY PER THE LATEST MODEL DATA. THEREFORE...NO MAJOR
UPDATE WAS MADE TO THE FORECAST.
UPDATE ISSUED AT 942 PM EDT SUN AUG 18 2013
THE WIDELY SCATTERED SHOWERS AFFECTING THE AREA DURING THE EVENING
HAVE DECREASED IN COVERAGE AT THIS TIME ON THIS SIDE OF THE KY/VA
BORDER. TO THE EAST OF THE BORDER...A BAND OF SHOWERS CONTINUES TO
ADVANCE NORTHEASTWARD. THESE SHOWERS WILL SKIRT OUR VA BORDER
COUNTIES THROUGH THE NIGHT INTO TOMORROW MORNING AND WILL MAINTAIN
HIGHEST POPS IN THAT AREA...WITH DIMINISHING RAIN CHANCES TO THE
WEST. LATEST HRRR RUN SHOWS SOME SHOWERS DEVELOPING BACK FURTHER TO
THE WEST TOWARDS DAWN AND WITH THE FILLING UPPER LOW NEARBY...WILL
MAINTAIN AT LEAST A 20 POP EVERYWHERE THROUGH THE NIGHT INTO THE DAY
TOMORROW.
OTHERWISE...ADDED PATCHY FOG INTO THE FORECAST AS ANY BREAKS IN THE
CLOUDS WILL ALLOW IT TO FORM RATHER QUICKLY OVERNIGHT BUT NO OTHER
CHANGES WERE NEEDED AT THIS TIME.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 220 PM EDT SUN AUG 18 2013
UPPER LOW SPINNING OVER WRN KY WILL CONTINUE TO EASE TO THE EAST AS
HIGH PRESSURE SLOWLY RELEASES IT/S HOLD ON THE REGION AND SLIPS TO
THE MID ATLANTIC COAST. MEANWHILE A SFC LOW COMING ONSHORE NEAR THE
MID GULF COAST CONTINUES TO PUSH MOISTURE AND A BLANKET OF CLOUDS
INTO ERN KY. EXPECT THE RAIN TO CONTINUE OVER ERN KY FOR THE NEXT
24-30 HRS AS THE UPPER LOW EDGES ACROSS THE STATE AND FINALLY MOVES
NE TOWARDS THE NEW ENG COAST. THE GULF COAST LOW WILL SLOWLY TRACK NE
AND LINK UP WITH THE UPPER LEVEL SYSTEM BEFORE SWEEPING INTO THE
POCONOS. HIGH PRESSURE WILL THEN BUILD BACK INTO THE AREA AND GIVE
THE REGION A SMALL WINDOW TO DRY OUT ON MON NIGHT. BUT THE MOISTURE
SPLAYED ACROSS THE AREA TODAY AND TONIGHT WILL SET THE STAGE FOR FOG
MON NIGHT AS A FEW BREAKS IN THE CLOUD COVER WILL ALLOW TEMPS TO
DROP FROM A MON HIGH AROUND 80 TO LOWS AT OR NEAR THE DEWPOINT TEMPS
IN THE LOWER 60S FOR MON NIGHT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 231 PM EDT SUN AUG 18 2013
MODELS HAVE CHANGED COURSE A BIT GOING INTO TUESDAY AND WEDNESDAY AS
ANOTHER MID/UPPER LEVEL LOW WILL DEVELOP OVERHEAD. ON
TUESDAY...MOISTURE WILL BE ON THE INCREASE FROM THE SOUTH. MUCH LIKE
ON SATURDAY...DOWNSLOPING SOUTHEAST WINDS WILL HAMPER THE NORTHWARD
PROGRESS OF ANY PRECIPITATION AND KEEP INSTABILITY AT BAY.
THUS...GOING TO CONFINE POPS TO MAINLY THE SOUTHERN 2 ROWS OF
COUNTIES IN KENTUCKY WITH ONLY A SLIGHT CHANCE. AREAS FURTHER NORTH
WILL LIKELY BE AFFECTED BY THE DOWNSLOPING CONDITIONS. BY TUESDAY
NIGHT...AS THE UPPER LEVEL LOW PUSHES SLIGHTLY EAST...WINDS WILL
VEER AROUND TO THE SOUTH OR SOUTHWEST ALLOWING MOISTURE TO SURGE
NORTHWARD. CLOUDS AND SHOWERS WILL OVERSPREAD THE AREA FROM LATE
TUESDAY NIGHT INTO WEDNESDAY. A MID LEVEL VORTICITY MAXIMUM WILL
PUSH EAST DURING THE DAY TO AID IN MORE VIGOROUS SHOWER ACTIVITY.
STILL SOME QUESTION AS TO INSTABILITY DURING THE DAY...AND MUCH LIKE
TODAY...CLOUD COVER COULD LIMIT INSTABILITY KEEPING ANY THUNDER AT
BAY. GOING TO CARRY A SLIGHT CHANCE FOR NOW...BUT FEEL THIS THUNDER
PROBABLY WILL NOT PAN OUT. THIS SYSTEM WILL FINALLY BE ON THE WAY
OUT BY THURSDAY WITH THE EXPECTED RIDGING FINALLY BUILDING ACROSS
THE REGION. THIS WILL SET UP THE SUMMER-LIKE PATTERN BY THURSDAY AND
THROUGH NEXT WEEKEND. THIS WILL YIELD A MINIMAL CHANCE FOR SHOWERS
OR STORMS EACH AFTERNOON...BUT ANTICIPATING THAT MOST AREAS WILL
REMAIN DRY FROM WEDNESDAY NIGHT ONWARD. TEMPERATURES WILL REMAIN A
TOUCH BELOW NORMAL INTO WEDNESDAY WITH THE CLOUD COVER AND
PRECIPITATION...BUT WILL WARM TO NEAR NORMAL FOR THE SECOND HALF OF
THE WEEK...AND AT THIS POINT...LOOKING FOR SLIGHTLY ABOVE NORMAL
READINGS BY NEXT WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 137 AM EDT MON AUG 19 2013
STILL BELOW AVERAGE CONFIDENCE IN FORECAST DETAILS FOR AREA AIRPORTS
TONIGHT AS CLOUDS ARE EXPECTED TO BREAK UP ENOUGH TO ALLOW FURTHER
LOW CLOUD AND FOG DEVELOPMENT OVERNIGHT WITH AMPLE LOW LEVEL MOISTURE
IN PLACE. HAVE FORECAST DETERIORATING CONDITIONS AT ALL 3 TAF SITES
WITH A PERIOD OF LIFR CIGS AND VSBYS AROUND DAWN. SHOULD MID LEVEL
CLOUDS HOLD ON THROUGH THE NIGHT...THIS WILL BE TOO PESSIMISTIC.
OTHERWISE...A FEW STRAY SHOWERS WILL BE POSSIBLE OVERNIGHT AND AGAIN
TOMORROW. WILL HANDLE THIS WITH A VCSH MENTION AT THIS TIME.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AR
SHORT TERM...DUSTY
LONG TERM...KAS
AVIATION...AR
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
128 AM EDT Mon Aug 19 2013
...Updated Aviation Discussion...
...Forecast Update...
Issued at 1140 PM EDT Sun Aug 18 2013
One more update to bump up coverage of fog some. Seeing visibilities
drop in a few spots late this evening. The clear spot to our west
has seen PAH drop down to a quarter mile in its latest ob. Will have
to watch for worse visibilities over our area tonight, but for now
the trend looks good. Still cannot rule out a stray shower
developing, as the upper trough axis still has not passed our
region. Have left in a slight chance across the southeast for a few
more hours tonight.
Issued at 625 PM EDT Sun Aug 18 2013
Active convection appears confined to a line running from north of
Hartford to west of Lawrenceburg in KY. Fine tuned the rain chances
to focus on this region next couple of hours. Still expect activity
to quiet down with loss of heating and as the upper low, which has
been near us for days, weakens and accelerates northeast.
Next issue will be the chance for fog. Statistical guidance hints at
visibilities lowering during the night, and this makes sense with
residual moisture. Cloud cover should keep us from going too dense
however. For now have added in patchy fog everywhere after midnight.
.SHORT TERM (Now through Monday Night)...
Issued at 300 PM EDT Sun Aug 18 2013
The cutoff upper low that was centered over the Mississippi and Ohio
River confluence this morning is filling, becoming an open wave, and
meandering eastward, as another shortwave trough begins to dive
southeast into the upper Mississippi Valley. Scattered showers and
isolated storms will be possible through the afternoon and early
evening hours, as heating combines with large-scale ascent. The
mid-level trough axis will swing across the area tonight, combined
with loss of heating, will put an end to convection. So, will have
scattered precipitation tapering off from west to east through the
evening hours, with a dry forecast from about midnight onward.
Will continue with dry conditions through Monday morning. However,
the trough across the upper Mississippi Valley tonight will spread
across the Ohio Valley by Monday afternoon. Appears some low-level
moisture will remain in place and with afternoon heating, could
spark some convection. Soundings indicate there should be slight
capping across much of the CWA, allowing mainly low-topped showers
to develop. By late in the afternoon the cap could weaken just
enough to squeeze out an isolated thunderstorm or two, but that
chance appears minimal. So, will run with isolated showers in the
forecast through the afternoon and early evening hours Monday. This
will generally be along and southeast of a line from Frankfort
southwestward to Bowling Green. Any activity will dissipate with
loss of heating, leaving the overnight hours dry.
Temperatures will drop into the lower 60s tonight, with a few breaks
in the cloud cover. Highs in the low to middle 80s will be common
Monday under partly cloudy skies. Expect lows in the low and middle
60s Monday night under partly cloudy to mostly clear skies. Cannot
rule out some patchy fog tonight and Monday night, but tonight will
depend on how much cloud cover is lost and Monday night will depend
on how much drying occurs through Monday afternoon.
.LONG TERM (Tuesday through Sunday)...
Issued at 300 PM EDT Sun Aug 18 2013
The long term period continues to look rather unsettled for much of
the upcoming work week as the Ohio Valley will remain in a rather
stagnant upper level pattern. However, the overall pattern looks to
improve a bit by the end of the week and into the weekend as the
latest forecast datasets point to upper level ridging building in
from the west which will result in warmer and more seasonal
temperatures for the region.
Until late week, the upper level flow is forecast to remain rather
blocky and complex as the band of westerlies remains holed up along
the US/Canadian border. Overall, there is not much forcing in the
hemispheric flow to kick things into gear and smooth the wave
pattern out. With that said, the model solutions show that a
bagging long wave trough axis will remain over the eastern part of
the US from Tuesday through at least late Thursday. With the trough
axis overhead, diurnally driven convection will be possible across
the region. While the overall coverage for the week looks to be
isolated to scattered, it does appear that the best chances for
rainfall would be Wednesday as the actual trough pulls through the
region. With this forecast we plan on keeping isolated-scattered
PoPs in the forecast each afternoon for Tuesday-Thursday with the
highest chances Wednesday. With regards to convection strength, the
combination of weak flow aloft and rather modest instability
suggests that severe weather is not likely. However, high
atmospheric moisture content combined with the weak steering flow
could lead to heavy rain production with any storm that develops.
Temperatures through the period will remain below normal. Have
sided again with the consensus raw datasets for max/min temperatures
as they have verified well over the last few days. This actually
results in a cooling trend applied for Tuesday/Wednesday due to
expected clouds and precipitation. Tues/Wed highs will average in
the lower 80s across the central/east/southeast with lower-middle
80s across the northwest/west sections. With the upper trough
passing to our east on Thursday, we expect less clouds and
precipitation which should allow temperatures to warm into the
middle 80s. Overnight lows will be rather mild with readings in the
upper 60s to the lower 70s.
By Friday, the model solutions start to show their normal spread.
The GFS solutions suggest a weak cold front will pass through the
region and then stall out to our south. On the other hand, the Euro
solution is not as progressive and allow the upper ridging to build
in which would keep the frontal boundary up to our north. For now
have, opted to keep the forecast on the dry side, but will continue
to monitor later forecasts to see if PoPs will be required. With the
upper ridge building in, Sat/Sun continue to look dry at this point.
Temperatures should continue to moderate through the period with
afternoon highs in the middle to upper 80s with overnight lows in
the upper 60s to the lower 70s.
&&
.AVIATION (06Z TAF Update)...
Issued at 125 AM EDT Mon Aug 19 2013
The TAF challenge this morning will be the extent and intensity of
fog and low cigs over the TAF sites as we sit in a very moist
environment with weak or calm winds. Observations across the region
reveal 2 areas of fog/low cigs...one over Illinois/western KY and
the other over southwest Ohio. The RAP is picking up on these areas
of fog/low cigs well and forecasts that they will expand into
SDF/BWG/LEX as the morning progresses. LEX seems to be the most
likely to see the worst flight conditions with MVFR conditions
likely to develop within the next few hours and decline to LIFR by
around 9 or 10Z. BWG/SDF seem to be more on the edges of the
projected fog/low cigs. Since BWG is very fog prone, did go ahead
and bring flight conditions into the LIFR cat by 9Z with a slightly
slower progression to that restriction than LEX. SDF seems to be
the least likely to see really low vsbys/cigs although based on the
latest RAP guidance, they will probably drop into the IFR cat just
before sunrise. If the fog/low cigs expand more than projected by
the RAP, SDF TAF will need to be amended with more flight
restrictions.
Fog/low cigs should improve by 13 or 14Z with VFR conditions
expected the rest of the day with a light ENE wind.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........RJS
Short Term.....MJP
Long Term......MJ
Aviation.......AMS
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
341 AM EDT MON AUG 19 2013
.SYNOPSIS...
AN UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE REGION TODAY AND
HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT THROUGH TUESDAY. A TROUGH
WILL IMPACT THE REGION DURING THE MIDDLE PORTION OF THE WEEK BEFORE
A COLD FRONT MOVES THROUGH FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
HAVE HAD SOME POCKETS OF CLEARING EARLY THIS MORNING WITH WEAK
SURFACE HIGH PRESSURE NEARBY. WITH LINGERING LOW LEVEL
MOISTURE...THIS HAS RESULTED IN PATCHY FOG MAINLY ACROSS THE
SHENANDOAH VALLEY/NORTHERN VIRGINIA PIEDMONT AREA. THIS WILL
PERSIST UNTIL SUNRISE.
ALSO HAVE SOME SHOWERS ACROSS SOUTHWEST VIRGINIA THAT EXIST AHEAD
OF AN UPPER TROUGH OVER THE OHIO VALLEY. HRRR HAS SHOWERS MAKING
THEIR WAY INTO THE SOUTHWEST CWA OVER THE NEXT SEVERAL HOURS. AS
THE TROUGH ADVANCES EASTWARD THROUGH THE DAY...ANTICIPATE NEW
SHOWER DEVELOPMENT IN THE PVA ZONE LATER THIS MORNING WEST OF THE
BLUE RIDGE AND THEN SPREADING EAST TOWARD THE METRO CORRIDOR IN
THE AFTERNOON.
DUE TO CLOUD COVER...INSTABILITY IS FORECAST TO BE WEAK AND LIKELY
LESS THAN 500 J/KG. THEREFORE HAVE ONLY ALLOWED FOR ISOLATED
THUNDER DURING THE AFTERNOON AND NO SEVERE IS EXPECTED.
SHOWERS WILL BE QUICK TO DISSIPATE THIS EVENING WITH THE SETTING
OF THE SUN AND WITH THE SHORTWAVE EXITING THE AREA. HIGH PRESSURE
BUILDS IN OVERNIGHT...AND FOG COULD BE MORE WIDESPREAD ESPECIALLY
IF CLEARING OCCURS.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION TUESDAY INTO
TUESDAY NIGHT...BRINGING DRY AND SEASONABLE CONDITIONS. MAX TEMPS
TUESDAY WILL RANGE FROM THE UPPER 70S IN THE MOUNTAINS TO THE
MIDDLE AND UPPER 80S ACROSS MOST OTHER LOCATIONS. MIN TEMPS
TUESDAY NIGHT WILL RANGE FROM THE 50S IN PORTIONS OF THE POTOMAC
HIGHLANDS TO THE LOWER AND MIDDLE 70S IN DOWNTOWN WASHINGTON AND
BALTIMORE.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
HIGH PRESSURE WILL MOVE OFF THE COAST WEDNESDAY AND A RETURN FLOW
WILL USHER IN WARM AND HUMID CONDITIONS. AN UPPER-LEVEL LOW WILL
ALSO BUILD TOWARD THE REGION FROM THE OHIO VALLEY. A FEW SHOWERS AND
THUNDERSTORMS ARE POSSIBLE...ESPECIALLY ACROSS THE SHENANDOAH VALLEY
AND POTOMAC HIGHLANDS...CLOSER TO THE UPPER-LEVEL LOW.
THE UPPER-LEVEL LOW WILL WEAKEN AND ROTATE THROUGH AS AN UPPER-LEVEL
TROUGH WEDNESDAY NIGHT AND THURSDAY. A SURFACE TROUGH WILL ALSO
REMAIN OVER THE REGION DURING THIS TIME. A FEW SHOWERS AND
THUNDERSTORMS ARE POSSIBLE...BUT MUCH OF THE TIME MAY TURN OUT DRY.
TEMPERATURES WILL BE NEAR CLIMO.
A COLD FRONT WILL PASS THROUGH THE REGION FRIDAY...BRINGING THE
CHANCE FOR MORE SHOWERS AND THUNDERSTORMS. HIGH PRESSURE MAY BUILD
IN BEHIND THIS SYSTEM DURING THE WEEKEND.
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
GREATEST POTENTIAL FOR FOG THIS MORNING WILL BE CHO...WITH A PERIOD
OF IFR IN THE TAF. CONFIDENCE IN LOW VIS DECREASES FURTHER NORTHEAST
WHERE DEWPOINTS ARE LOWER BUT BRIEF MVFR AT MRB/IAD IS POSSIBLE.
SHORTWAVE TROUGH WILL BRING SCATTERED SHOWERS...PROBABLY NOT UNTIL
THE AFTERNOON AT THE HUBS. AS HIGH PRESSURE BUILDS IN TONIGHT...VIS
RESTRICTIONS COULD BE MORE WIDESPREAD AND/OR LOWER LATE TONIGHT.
AREAS OF BR/FOG WILL LIKELY IMPACT THE TERMINALS EARLY TUESDAY
MORNING. VFR CONDITIONS ARE EXPECTED FOR THE REST OF TUESDAY INTO
TUESDAY NIGHT. PATCHY BR/FOG MAY IMPACT THE TERMINALS LATE TUESDAY
NIGHT.
A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE WEDNESDAY AND
THURSDAY...BUT MUCH OF THE TIME MAY TURN OUT DRY. A COLD FRONT MAY
PASS THROUGH THE TERMINALS FRIDAY.
&&
.MARINE...
WEAK GRADIENT WILL GENERALLY KEEP WINDS AOA 10 KT THROUGH TONIGHT.
WEAK TROUGH MAY BRING A FEW SHOWERS THIS AFTERNOON...THEN HIGH
PRESSURE BUILDS IN OVERNIGHT.
HIGH PRESSURE WILL REMAIN OVER THE WATERS TUESDAY BEFORE MOVING OFF
THE COAST WEDNESDAY. A RETURN FLOW WILL DEVELOP WEDNESDAY THROUGH
THURSDAY. WIND SPEEDS SHOULD REMAIN BELOW SCA CRITERIA DURING THIS
TIME. A COLD FRONT WILL PASS THROUGH THE WATERS LATE FRIDAY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BJL
NEAR TERM...BPP
SHORT TERM...BJL
LONG TERM...BJL
AVIATION...BJL/BPP
MARINE...BJL/BPP
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
404 AM EDT MON AUG 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 359 AM EDT MON AUG 19 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A ZONAL FLOW OVER
SRN CANADA TO THE N OF UPR RDG EXTENDING FM THE WRN PLAINS INTO THE
GREAT LKS. THE WX OVER UPR MI IS QUIET EARLY THIS MRNG...WITH
DRY/STABLE AIRMASS DEPICTED ON THE 00Z MPX/GRB RAOBS DOMINATING THE
AREA. THERE ARE 2 SHRTWVS EMBEDDED IN THE ZONAL FLOW THAT ARE OF
CONCERN. THE FIRST OF THESE IS MOVING EWD THRU THE DAKOTAS
AND ARPCHG NW MN...ACCOMPANIED BY SCT SHRA/TS. THE SECOND IS MOVING
THRU NW ONTARIO WITH A CLUSTER OF SHRA/TS NW OF LK NIPIGON...BUT
SOME ISOLD SHRA/TS WITHIN THE COMMA TAIL OF THIS FEATURE EXTEND
FARTHER S INTO THE MN ARROWHEAD UNDER SOME H85-5 QVECTOR CNVGC
ASSOCIATED WITH FAIRLY VIGOROUS H85 THETA E ADVECTION IN ADVANCE OF
AXIS OF HIER H85 DEWPTS UP TO 15C AT ABERDEEN SDAKOTA AND 13C AT
INL. WHILE THE 00Z MPX/GRB RAOBS ARE QUIET DRY/STABLE WITH KINX OF
0/-2 RESPECTIVELY AND PWAT ARND 0.75 INCH /NEAR 75 PCT OF
NORMAL/...THE 00Z INL RAOB IS MORE MOIST AND CONDITIONALLY
UNSTABLE...WITH KINX OF 36 AND PWAT 1.47 INCH /175 PCT OF NORMAL/.
DESPITE THE RATHER IMPRESSIVE MOISTENING...LATEST TRENDS INDICATE
FEW IF ANY LTG STRIKES WITHIN THE CONVECTION.
MAIN FCST CONCERNS IN THE SHORT TERM ARE RELATED TO PCPN CHCS
ASSOCIATED WITH PAIR OF SHRTWVS NOTED ABOVE.
TDAY...SHRTWVS MOVING INTO MN AND THRU ONTARIO ARE PROGGED TO
CONTINUE DRIFTING E THRU THE DAY. AS AXIS OF VIGOROUS H85 THETA E
ADVECTION/H85-5 QVECTOR CNVGC SHIFT E THIS MRNG...EXPECT SOME ISOLD
SHRA TO INVADE THE WRN COUNTIES. BUT MODEL GUIDANCE IN GENERAL SHOWS
THE SHARPER H85-5 QVECTOR CNVGC ASSOCIATED WITH THE ONTARIO SHRTWV
PASSING TO THE N AND MORE VIGOROUS FORCING IN ADVANCE OF THE MN
DISTURBANCE FOCUSING TO THE S BEFORE FADING IN THE AFTN. SO GOING
FCST SHOWING A DIMINISHING TREND IN THE POPS THRU THE MRNG SEEMS ON
TRACK. GIVEN OBSVD LTG STRIKES AND TENDENCY FOR DIMINISHING DYNAMIC
SUPPORT...REMOVED MENTION OF TS THIS MRNG. WHETHER DAYTIME HEATING
/DESTABILIZATION CAN REINVIGORATE/SUSTAIN ANY CONVECTION WL BE THE
CONCERN FOR THE AFTN. IN FACT...THE 00Z REGIONAL GEM AND GFS ARE THE
ONLY MODELS THAT GENERATE ANY PCPN OVER THE CWA THIS AFTN. THE GFS
FCST SDNGS SHOW RATHER UNIMPRESSIVE LAPSE RATES WITH A TENDENCY FOR
A PERSISTENT CAP AND WARMING MID LVL TEMPS IN THE 18Z-24Z TIME FRAME
ASSOCIATED WITH THE FADING DYNAMIC SUPPORT. NAM/GFS MOS POPS ARE
UNDER 10 AT MOST PLACES...BUT OPTED TO RETAIN SCHC POPS TO INCLUDE
TS WITH ARRIVAL OF MOISTER AIR/PWAT UP TO 1.5 INCH AND SFC TEMPS
EXPECTED TO REACH ARND 85 THAT WL LIFT MUCAPE UP TO 800-1000J/KG
AWAY FM THE MODERATING INFLUENCE OF THE LKS.
TNGT...WITH RISING HGTS/DNVA/DEEP QVECTOR DVGC...TNGT WL BE DRY AS
ANY AFTN CONVECTION FIZZLES BEFORE SUNSET UNDER THE MID LVL
WARMING/LOWERING SUN ANGLE. ALTHOUGH SKIES WL TURN MOCLR...STEADY SW
WIND SHOULD ACT TO LIMIT THE DIURNAL TEMP FALL. THE WARMEST MIN
TEMPS ARE MOST LIKELY NEAR LK SUP OVER THE W HALF...WHERE THE PRES
GRADIENT WL BE A BIT TIGHER/H925 WINDS 20-25 KTS AND THIS FLOW WL
DOWNSLOPE.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 359 AM EDT MON AUG 19 2013
STARTING TUE...THE CWA WILL BE BETWEEN A SFC HIGH OVER THE
ATLANTIC/ERN CONUS AND AND SFC TROUGH FROM HUDSON BAY INTO THE NRN
PLAINS STATES. SOME OF THE MODELS ARE HINTING AT SOME PRECIP TUE
AFTERNOON...BUT ANY PRECIP SHOULD BE ISOLATED AT BEST GIVEN THAT
THERE WILL NOT BE MUCH MOISTURE AVAILABLE. BEST CHANCE FOR ISOLATED
SHOWERS AND THUNDERSTORMS WILL BE OVER NCENTRAL UPPER MI WHERE LAKE
BREEZE CONVERGENCE WILL HELP ENCOURAGE CONVECTION ALONG. 850MB TEMPS
AT 18Z TUE WILL BE RIGHT AROUND 17-18C AND WITH MOSTLY SUNNY SKIES
SHOULD BE ABLE TO GET HIGH TEMPS IN THE 80S TO AROUND 90.
MODELS ARE IN BETTER AGREEMENT FOR THAT TROUGH/COLD FRONT TO THE NW
TO DROP ACROSS THE CWA ON WED/WED NIGHT...BUT THERE REMAINS SOME
SUBTLE YET IMPORTANT UNCERTAINTY FOR THE SYSTEM. MAIN QUESTION IS
WITH THE EXACT TIMING OF THE COLD FRONT...WHICH EVEN THOUGH MODELS
AGREE WELL ON...THINK THAT IT WILL NOT BE CERTAIN UNTIL A LATER
TIME. THE TIMING OF FROPA IS IMPORTANT BECAUSE WITH 850MB TEMPS UP
TO 20C...TEMPS MAY BE COLDER THAN WHAT IS IN THE FORECAST /MAINLY
OVER THE W WHERE THE FRONT MAY COME IN EARLIER THAN PREVIOUSLY
INDICATED BY MODELS/. THINK THAT AREAS THAT HAVE NOT BEEN IMPACTED
BY THE FRONT /AND ASSOCIATED PRECIP AND CLOUD COVER/ BY AROUND PEAK
HEATING TIME WILL GET INTO THE LOW 90S /AWAY FROM LAKE MICHIGAN/.
SO...IF THE COLD FRONT COMES IN AS THE MODELS ARE CURRENTLY
INDICATING /INTO WRN UPPER MI BY 18Z WED AND CENTRAL UPPER MI BY 00Z
THU/...PORTIONS OF WRN UPPER MI WOULD SEE HIGH TEMPS POSSIBLY 10
DEGREES COLDER THAN WHAT THE PREVIOUS FORECAST HAD. ON THE FLIP
SIDE...THE FRONT COULD VERY WELL COME IN LATER THAN INDICATED BY
MODELS...MEANING THE PREVIOUS FORECAST MAY BE RIGHT ON. AT THIS
POINT WITH THE UNCERTAINTY...WILL NOT CHANGE TEMPS MUCH FOR WED. THE
OTHER IMPACT WITH FROPA TIMING IS ON CONVECTION...SIGNIFICANT SBCAPE
VALUES OF 1500-2500J/KG SHOULD BE PRESENT IN AIRMASS AHEAD OF COLD
FRONT AROUND PEAK HEATING...SO WHEN THE FRONT MOVES THROUGH WILL
DETERMINE STRENGTH/COVERAGE OF CONVECTION. AT THIS POINT...NOT TOO
EXCITED WITH AREAL EXTENT OF CONVECTION GIVEN THAT MOISTURE WILL BE
SOMEWHAT LIMITED /AT LEAST EARLY ON/. AT THE SAME TIME...THAT DRY
AIR WILL HELP DCAPE VALUES GET UP TO AROUND 1000J/KG AND WITH HIGH
FREEZING LEVEL AROUND 14KFT...MAIN THREAT FROM ANY STRONGER OR
ISOLATED SEVERE STORMS WOULD BE STRONG WINDS.
THURSDAY CERTAINLY LOOKS COOLER AND DRIER AS 850MB TEMPS AT 18Z THU
WILL BE AROUND 13C WITH SFC HIGH PRESSURE MOVING IN FROM THE W. HIGH
TEMPS LOOK TO BE IN THE 70S TO AROUND 80 OVER THE SCENTRAL CWA.
AMPLIFIED UPPER LEVEL RIDGE WILL BE WELL TO THE W OF THE CWA.
MODELS IN MUCH BETTER AGREEMENT FOR FRI WITH HAVING THE SFC HIGH
EXIT TO THE E ON FRI AS THE UPPER RIDGE AXIS MOVES OVERHEAD LATE IN
THE DAY. WITH SLY FLOW NOT KICKING IN AND UPPER RIDGE NOT ARRIVING
UNTIL LATE IN THE DAY OR UNTIL FRI NIGHT...WILL NOT HAVE SUFFICIENT
ADVECTION OF WARMER AIRMASS INTO THE AREA. HIGH TEMPS LOOK SIMILAR
OR A DEGREE OR TWO COOLER THAN THURSDAY...WITH HIGHS PRIMARILY IN
THE 70S /WITH SOME COOLER SPOTS NEAR LAKE SUPERIOR/.
UNCERTAINTY INCREASES CONSIDERABLY FOR SAT AND SUN DUE TO MODEL
DISAGREEMENT AND RUN TO RUN DISCONTINUITY. WILL JUST USE CONSENSUS
OF MODELS FOR THIS PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 121 AM EDT MON AUG 19 2013
WITH SW FLOW OF RELATIVELY DRY AIR...EXPECT VFR CONDITIONS TO
PREVAIL THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. INCREASING SW WINDS
ABOVE NOCTURNAL INVERSION LATE TONIGHT WILL APPROACH LLWS CRITERIA.
ALSO A DISTURBANCE APPROACHING FROM THE W MAY BRING ISOLD/SCT
CONVECTION INTO CENTRAL UPPER MI LATE MON AFTERNOON. AT THIS
POINT...CONFIDENCE IS VERY LOW ON LOCATION/COVERAGE OF SHRA/TSRA.
THUS...WILL ONLY MENTION VCSH AT KSAW AROUND 21Z MON.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 359 AM EDT MON AUG 19 2013
OVERALL...EXPECT WINDS LESS THAN 20 KTS THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. THE ARRIVAL OF MORE HUMID AIR FOR TUE/WED MAY
RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE WATERS.
HOWEVER...FOG WILL BE MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS
OCCUR OVER THE LAKE. ANY FOG WILL DISSIPATE THU FOLLOWING A COLD
FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...VOSS
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
121 AM EDT MON AUG 19 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 409 PM EDT SUN AUG 18 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE OVER THE SRN U.S.
ROCKIES WITH A TROF LINGERING OVER THE LWR MISSISSIPPI VALLEY. TO
THE N...ZONAL FLOW DOMINATES SRN CANADA. THERE ARE A COUPLE OF
SHORTWAVES OF INTEREST UPSTREAM IN THIS ZONAL FLOW. THE FIRST IS
OVER SE MANITOBA...AND THE SECOND IS OVER SRN SASKATCHEWAN/ERN MT.
THE FIRST WAVE IS GENERATING CONVECTION OVER FAR SE MANITOBA INTO
ADJACENT NRN ONTARIO. THE SECOND WAVE IS GENERATING SCT SHRA/TSRA
OVER THE WRN DAKOTAS INTO SRN SASKATCHEWAN. CLOSER TO HOME...12Z
SOUNDINGS FROM KGRB/KMPX SHOWED VERY DRY MID LEVELS AND A HEALTHY
CAP...AND THUS NO PCPN IS OCCURRING OVER THE FCST AREA THIS AFTN.
SOME CI AND A RATHER THICK ELEVATED SMOKE LAYER HAS HELD TEMPS DOWN
A BIT FROM EXPECTATIONS WITH READINGS MOSTLY IN THE UPPER 70S TO LOW
80S AS OF 19Z. NEAR LAKE MICHIGAN...SOUTHERLY WINDS OFF THE LAKE ARE
HOLDING TEMPS TO THE LOW/MID 70S.
AFTER A DRY START TO THE SHORT TERM...ATTENTION TURNS TO THE
POTENTIAL OF SHRA/TSRA LATE TONIGHT/MON AS THE PAIR OF SHORTWAVES
CURRENTLY OVER SE MANITOBA AND OVER SRN SASKATCHEWAN/ERN MT MOVES
EASTWARD. INITIAL DRY/CAPPED AIR MASS WILL ENSURE DRY WEATHER ACROSS
THE FCST AREA THIS EVENING. THEN...SW FLOW AHEAD OF SHORTWAVES WILL
TRANSPORT INTO THE UPPER LAKES THE MORE HUMID AIR MASS EVIDENT OVER
THE CNTRL PLAINS THIS MORNING PER 12Z RAOBS. WHILE THE ANTECEDENT
DRY AIR WILL WORK TO DELAY SHRA...DEGREE OF MOISTENING/MAGNITUDE OF
THETA-E ADVECTION SUGGESTS THERE WILL BE SOME RISK OF PCPN. THERE MAY
BE 2 RATHER DISTINCT CLUSTERS OF SCT SHRA/TSRA. THE FIRST ASSOCIATED
WITH THE SE MANITOBA SHORTWAVE COULD REACH NW LAKE SUPERIOR/ISLE
ROYALE AREA EARLY IN THE OVERNIGHT. 850-300MB THICKNESS FIELD
SUGGESTS SOME OF THE CURRENT SHRA/TSRA ASSOCIATED WITH THE WAVE MAY
TAKE A SHARP TURN TO THE RIGHT AS THEY APPROACH THE LAKE...SO IT
REMAINS TO BE SEEN WHERE THESE SHRA MAY END UP. THE SECOND AREA OF
CONVECTION MAY DEVELOP ACROSS NRN MN TOWARD WRN LAKE SUPERIOR LATE
IN THE NIGHT OR MON MORNING WITH THE FOLLOWING SHORTWAVE. IN BOTH
CASES...THERE IS AN INDICATION OF WEAKENING MOISTURE TRANSPORT
EASTWARD WITH TIME...SO SHRA WILL PROBABLY BE ON A DIMINISHING TREND
AS THEY MOVE TOWARD LAKE SUPERIOR/UPPER MI. AT THIS POINT...SEE NO
REASON TO DEVIATE MUCH FROM INHERITED FCST WHICH BROUGHT CHC POPS TO
WRN LAKE SUPERIOR OVERNIGHT AND SCHC POPS TO WRN UPPER MI LATE.
INCREASING COLUMN MOISTURE AND STIRRING S TO SW WINDS WILL WORK TO
KEEP TEMPS HIGHER THAN LAST NIGHT. EXPECT MINS IN THE MID 60S IN THE
DOWNSLOPE AREAS NEAR LAKE SUPERIOR. MINS IN THE MID 50S TO PERHAPS
AS LOW AS 50F IN TRADITIONAL COLD SPOTS SHOULD BE THE RULE INLAND.
ON MON...SHORTWAVE TROF MOVES ACROSS THE UPPER LAKES...BUT WILL BE
WEAKENING AS EVIDENT IN HEIGHT FIELD AND DEEP LAYER FORCING PER
QVECTORS. IF ANY SHRA/TSRA REACH THE W LATE TONIGHT...THEY WILL
LIKELY WEAKEN IN THE MORNING. DURING THE AFTN...MLCAPE IS FCST TO
INCREASE TO POSSSIBLY AS MUCH AS 800-1000J/KG. HOWEVER...WITH
DIMINISHING FORCING AND POTENTIALLY LITTLE IN THE WAY OF LAKE BREEZE
CONVERGENCE...COVERAGE OF ANY DIURNALLY DRIVEN CONVECTION WILL
PROBABLY BE QUITE LIMITED. WILL MAINTAIN JUST SCHC POPS FOR THE AFTN
HRS. MAX TEMPS SHOULD GENERALLY BE IN THE MID 80S PER FCST
SOUNDINGS. OF COURSE...SOUTHERLY WINDS WILL KEEP AREAS NEAR LAKE
MICHIGAN A LITTLE COOLER.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 409 PM EDT SUN AUG 18 2013
STARTING OUT ON MONDAY EVENING THE UPPER AIR PATTERN LOOKS ZONAL
WITH WEAK TROUGHING OVER THE GREAT LAKES AND A RIDGE CENTERED OVER
THE SOUTHWEST CONUS. RIDGE WILL HAVE HARD TIME AMPLIFYING FARTHER
NORTH INTO CANADA THIS WEEK THOUGH AS STRONGER WESTERLIES H5-H3
STREAM ACROSS SOUTHERN TIER OF CANADA OUT OF A MORE OR LESS
PERSISTENT TROUGH SET UP OVER GULF OF ALASKA. EVENTUALLY...WEDNESDAY
NIGHT INTO THURSDAY...LARGER SCALE HEIGHTS FALL SOME AS STRONGER
SHORTWAVE/JET MAX...PART OF WHICH IS STREAMING TOWARD WESTERN SHORE
OF BRITISH COLUMBIA TODAY...DIGS ACROSS NORTHERN ONTARIO TO WESTERN
QUEBEC. SFC COLD FRONT CROSSES UPPER LAKES WEDNESDAY AFTN INTO
WEDNESDAY NIGHT JUST AHEAD OF BETTER HEIGHT FALLS BEGIN LATE
WEDNESDAY. FRONT REPRESENTS BEST CHANCE OF SHRA/TSRA THIS WEEK. HIGH
PRESSURE BUILDS IN BEHIND THE FRONT...BUT QUESTION OF THE DAY IS FOR
HOW LONG. THIS WILL HAVE IMPACT ON FORECAST FOR FRIDAY THROUGH NEXT
WEEKEND.
INITIAL SHORTWAVE THAT ROLLS ACROSS UPPER LAKES ON MONDAY WILL
MAINLY BE EAST OF CWA MONDAY EVENING. SOUNDINGS SHOW PERHAPS MID
CLOUDS THROUGH THE NIGHT BUT WITH SUBSIDENCE IN WAKE OF WAVE...NOT
EXPECTING ANY SHRA/TSRA. ANOTHER WARM NIGHT IN THE 60S WITH STEADY
SW SFC WINDS BENEATH STRONGER WINDS AT 950-925MB. STRONGER WINDS
ALOFT FADE BY TUESDAY AFTN WHICH MAY RESULT IN LOCALIZED BACKING OF
WINDS/LAKE BREEZE ALONG LK SUPERIOR NCNTRL. LAKE MODIFICATION ONLY
ALONG LK MICHIGAN ELSEWHERE. MID CLOUDS MAY DAMPEN SUN INITIALLY...
BUT SHOULD SEE FULL SUN FOR A WHILE BTWN MID MORNING AND MID AFTN
ALLOWING TEMPS TO WARM WELL INTO THE 80S AND PROBABLY TO THE LOWER
90S IN SOME WESTERN CWA LOCATIONS. WILL HAVE TO REACH AT LEAST MID
80S BEFORE CU BEGINS TO FORM AND CONVECTIVE TEMPS ARE ON THE HIGH
SIDE IN THE LOWER 90S. SUPPOSE ALONG THE CONVERGENCE OF LAKE BREEZE
THERE COULD BE AN ISOLD STORM GIVEN MLCAPES OVER 2000J/KG. MOISTURE
THAT IS AROUND PER SOUNDINGS IS VERY SHALLOW SO WITHOUT MUCH
ADDITIONAL LARGE SCALE SUPPORT...THINK CHANCES ARE VERY MINIMAL. IF
A STORM CAN FORM...WOULD HAVE POTENTIAL FOR GUSTY WINDS AS DCAPE
VALUES ARE OVER 1000J/KG. SOUNDINGS POINT TO QUIET...WARM AND HUMID
CONDITIONS TUESDAY NIGHT IN THE WARM SECTOR. MAY SEE A TOUCH OF
FOG...THOUGH SOME WIND JUST OFF THE SFC WILL LIMIT THE EXTENT.
MOIST ONSHORE FLOW MAY LEAD TO MORE FOG CLOSER TO LK MICHIGAN SHORE.
WARM WEATHER CONTINUES ON WEDNESDAY. AFTER A WARM START NEAR 70
DEGREES IN SOME SPOTS IT WILL NOT TAKE MUCH TO SEE READINGS REACH
THOSE SIMILAR TO TUESDAY. COLD FRONT MAKES IT TO MN ARROWHEAD JUST
TO WEST OF DLH BY MIDDAY SO A LOT OF TIME FOR WARMING IN A CAPPED
AIRMASS WITH WARM NOSE AROUND 800MB. SOUNDINGS THROUGH 00Z THURSDAY
LOOK PRETTY DRY WHICH MAKES SENSE AS PRIMARY SHORTWAVE AND MOISTURE
ADVECTION IS NORTH OVR ONTARIO. SW WINDS COULD INCREASE THROUGH THE
DAY AS 950-925MB WINDS INCREASE. STILL THINK TEMPS ON WEDNESDAY MAY
END UP A BIT WARMER THAN TUESDAY WITH LATER ARRIVAL TO FRONT AND AS
H85 TEMPS ARE NEAR +20C TO START THE DAY. DOWNSLOPE MAY LEAD TO
FURTHER WARMING ALONG LK SUPERIOR FROM ONTONAGON TO MUNISING. WILL
BUMP TEMPS INTO UPR 80S ON AVERAGE AND PUSH DOWNSLOPE AREAS TO
AROUND 90. INSTABILITY OBVIOUSLY PRESENT AHEAD OF FRONT WITH THE
VERY WARM TEMPERATURES AND INCREASE IN BLYR MOISTURE /DWPNTS ARE WELL
INTO THE 60S/. RESULT IS MLCAPES 1500-2000J/KG JUST AHEAD OF THE
FRONT. THINK QUALITY OF MOISTURE ULTIMATELY WILL LIMIT CONVECTION
COVERAGE WITH THE FROPA. GIVEN THE INSTABILITY AND DEEP LAYER SHEAR
UP TO 30 KTS THERE IS AT LEAST A MARGINAL POTENTIAL FOR ISOLD SVR
STORMS THROUGH WEDNESDAY EVENING. HIGHER FREEZING LEVEL OVER 14KFT
AND DRY AIR ALOFT /DCAPE OVER 1000J/KG/ POINTS TO STRONG WIND GUSTS
AS MAIN HAZARD.
GOOD AGREEMENT THAT STRONG DRYING/SUBSIDENCE ENDS ANY SHRA/TSRA
OVERNIGHT WEDNESDAY NIGHT WITH THURSDAY STILL LOOKING MUCH COOLER
AND MAINLY DRY AS HIGH PRESSURE BUILDS ACROSS UPPER GREAT LAKES.
GUSTY NORTH TO NORTHWEST WINDS ALONG WITH COLD AIR ADVECTION SHOULD
KICK UP WINDS AND WAVES ON LK SUPERIOR LEADING TO ELEVATED SWIM
RISK. TEMPS WILL STRUGGLE TO 70 DEGREES NEAR LK SUPERIOR AND COULD
REACH LOWER 80S FAR SOUTH.
EVEN THOUGH THURSDAY IS AGREED UPON FOR COOLER AND MAINLY DRY
WEATHER THE FORECAST FOR THURSDAY NIGHT INTO FRIDAY NOT NEARLY AS
CLEAR CUT. GFS MAINTAINS CONTINUITY WITH RECENT RUNS BY SHOWING
SPRAWLING HIGH SHUNTING MAIN FRONTAL BOUNDARY AND FOCUS FOR RETURN
FLOW SHRA/TSRA OVER THE NORTHERN PLAINS AND OHIO VALLEY UNTIL AT
LEAST SATURDAY NIGHT. MEANWHILE...ECMWF UP TO 12Z RUN TODAY WAS
CONSISTENT SINCE 00Z RUN ON 17 AUG INDICATING ONLY A BRIEF HIGH
PRESSURE INTRUSION. ECMWF THEN SHOWS NEXT SHORTWAVE IN WESTERLY FLOW
FORMING A STRONGER SFC-H85 LOW OVER THE NORTHERN PLAINS THURSDAY
WITH ASSOCIATED WARM AIR ADVECTION SHRA/TSRA IMPACTING UPPER LAKES
AS EARLY AS THURSDAY NIGHT AND FRIDAY. ECMWF CERTAINLY ON THE
AMPLIFIED SIDE COMPARED TO ECMWF ENSEMBLE WHICH LOOKS MORE LIKE THE
OPERATIONAL GFS. LATEST ECMWF HAS BACKED AWAY FROM THIS IDEA THOUGH
JUST ADDING MORE UNCERTAINTY TO THIS TIME FRAME. DROPPED POPS FOR
THU NIGHT AND FRIDAY TO SLIGHT CHANCE...BUT WANTED TO KEEP SOME POPS
IN THERE IN CASE MODELS SHIFT BACK TO WETTER IDEA. MUDDLED FORECAST
CONTINUES THROUGH NEXT WEEKEND AS TIMING FOR SYSTEMS MOVING
THROUGH REST OF THE WEEKEND IS STILL OUT OF WHACK BTWN THE GFS AND
ECMWF. CONSENSUS APPROACH WORKS FOR NOW UNTIL THESE DETAILS CAN BE
BETTER SORTED OUT. AFTER THE COOLER TEMPS THURSDAY AND FRIDAY...SEEMS
THAT TEMPS WILL REACH BACK TOWARD NORMAL AND MAYBE EVEN ABOVE NORMAL
IF THERE IS NOT MUCH IN WAY OF CLOUDS OR PRECIPITATION.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 121 AM EDT MON AUG 19 2013
WITH SW FLOW OF RELATIVELY DRY AIR...EXPECT VFR CONDITIONS TO
PREVAIL THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. INCREASING SW WINDS
ABOVE NOCTURNAL INVERSION LATE TONIGHT WILL APPROACH LLWS CRITERIA.
ALSO A DISTURBANCE APPROACHING FROM THE W MAY BRING ISOLD/SCT
CONVECTION INTO CENTRAL UPPER MI LATE MON AFTERNOON. AT THIS
POINT...CONFIDENCE IS VERY LOW ON LOCATION/COVERAGE OF SHRA/TSRA.
THUS...WILL ONLY MENTION VCSH AT KSAW AROUND 21Z MON.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 409 PM EDT SUN AUG 18 2013
OVERALL...EXPECT WINDS LESS THAN 20 KTS THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. SOME STRONGER SW WIND GUSTS UP TO 20-25KT MAY
OCCUR TONIGHT UNDER A SHARPER PRES GRADIENT AHEAD OF AN APPROACHING
DISTURBANCE. THE ARRIVAL OF MORE HUMID AIR FOR TUE/WED MAY RESULT IN
SOME FOG FORMATION OVER THE COOLER LAKE WATERS. HOWEVER...FOG WILL
BE MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS OCCUR OVER THE LAKE.
ANY FOG WILL DISSIPATE THU FOLLOWING A COLD FRONTAL PASSAGE AND THE
ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
326 AM EDT MON AUG 19 2013
.SYNOPSIS...
A WARM FRONT WILL GRADUALLY BRING MORE SEASONABLE TEMPERATURES
OVER THE NEXT FEW DAYS. WEAK UPPER LEVEL DISTURBANCES WILL KEEP
THUNDERSTORMS SCATTERED THROUGH THE MIDDLE OF THE WEEK. THE LATE
WEEK PERIOD WILL TURN EVEN WARMER WITH LOWER RAIN CHANCES.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM MONDAY...MODEL GUIDANCE EJECTS THE UPPER LOW OVER THE
MISSISSIPPI VALLEY TO THE NORTHEAST TODAY AND TONIGHT. THE MOTION
OF THIS FEATURE WILL ALLOW LIFT ASSOCIATED WITH THE ENTRANCE REGION
OF THE UPPER JET TO AFFECT THE AREA TODAY...PARTICULARLY NW
SECTIONS. IN ADDITION MODEL GUIDANCE SHOWS WEAK ISENTROPIC LIFT
OVER THE AREA TODAY AND THE OLD FRONTAL BOUNDARY REMAINS IN THE
AREA AS WELL. FORECAST WILL HAVE HIGH CHANCE TO LIKELY POPS TODAY
WITH HIGHEST NUMBERS NW...TAPERING BACK TO SLIGHT CHANCE TONIGHT.
AFTERNOON MAXIMUM TEMPERATURES UNDER A PARTLY TO MOSTLY CLOUDY SKY
SHOULD BE LIMITED TO THE MIDDLE 80S. MINS TONIGHT SHOULD FALL TO
THE LOWER 70S...PERHAPS UPPER 60S NW.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 AM MONDAY...MODELS HAVE SLOWED IN SHOWING THE INLAND
PROGRESSION OF THE MID LEVEL WEST ATLANTIC RIDGE. NOW TUESDAY IS
DEPICTED AS ONE LAST DAY WHERE MOISTURE REMAINS DEEP AND A FEW WEAK
SHORTWAVES EMBEDDED IN THE 10KT 500MB FLOW PROVIDE SOME SYNOPTIC
SCALE ASCENT. TEMPERATURES WILL BE CLOSE CLIMO BUT SLIGHTLY HIGHER
THAN NORMAL POPS APPEAR TO BE WARRANTED. WEDNESDAY THE WEST ATLANTIC
RIDGE GAINS IN AMPLITUDE BACKING LOCAL FLOW ALMOST TO SOUTHERLY.
MEANWHILE THE CHANNEL OF DEEPEST MOISTURE GETS SHUNTED JUST TO OUR
WEST. ISO TO WIDELY SCATTERED CONVECTION TILL POSSIBLE ALONG
MESOSCALE BOUNDARIES AND TEMPS MAY RISE A FEW DEG ABOVE TUESDAY
COUNTERPARTS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 3 AM MONDAY...FOR THE FIRST FEW DAYS OF THE LONG TERM THE WEST
ATLANTIC UPPER RIDGE BUILDS IN FAVOR OF THE BUILDING RIDGE OVER THE
WESTERN U.S. A WEAK SHEAR AXIS CROSSES THE REGION THURSDAY NIGHT
INTO FRIDAY. WEAK ASCENT ASSOCIATED WITH THIS FEATURES SHOULD BRING
SOME HIGHER RAIN CHANCES THAN WEDNESDAY BUT STILL PROBABLY NOT MUCH
HIGHER THAN CLIMO. THE REMAINDER OF THE PERIOD KEEPS A STRONG UPPER
RIDGE ACROSS THE MIDDLE OF THE NATION WITH TROUGHINESS ALONG BOTH
COASTLINES. BARRING THE RELATIVELY NEW IDEA OF THE GFS OF A BACKDOOR
COLD FRONT OVER THE WEEKEND THIS WILL MEAN SLIGHTLY ABOVE CLIMO
TEMPS AND SLIGHTLY LOWER THAN NORMAL THUNDERSTORM COVERAGE.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 06Z...SURFACE DEWPOINTS IN THE LOW TO MID 70S WITH CALM/LIGHT
WINDS SUGGEST THE LOW-LEVEL CONDITIONS ARE PRIMED FOR FOG/STRATUS
OVERNIGHT. MVFR CIGS/VSBYS ARE EXPECTED AT THE COASTAL TERMS...WITH
PERHAPS SOME BRIEF IFR VSBYS AT FOG-PRONE KCRE. KFLO/KLBT HAVE THE
BEST CHANCES FOR IFR...AS THE LATEST GUIDANCE FAVORS STRATUS
DEVELOPING AROUND DAYBREAK AT THE INLAND SITES. THE LATEST HRRR RUNS
SHOW SOME SHOWERS MOVING ONSHORE IN THE EARLY MORNING HOURS...SO
HAVE MENTIONED PCPN FOR THE COASTAL SITES AS WELL. CURRENT SHOWER
ACTIVITY INLAND HAS A CHANCE TO AFFECT THE INLAND TERMINALS THROUGH
ABOUT 09Z...PARTICULARLY FLO. MORE WIDELY SCATTERED SHOWERS ARE
EXPECTED WITH DAYTIME HEATING AS A COASTAL TROUGH WILL BE POSITIONED
OVER THE CAROLINAS. CIGS MAY BOUNCE AROUND BETWEEN VFR AND MVFR
DURING THE DAY...WITH MVFR MORE LIKELY DURING PERIODS OF SHRA.
SLIGHTLY HIGHER POPS INLAND ARE REFLECTED IN THE TAFS. CALM TO LIGHT
WINDS WILL BECOME S-SE AOB 10 KTS AT KMYR...KCRE AND KILM IN THE
AFTN HOURS.
EXTENDED OUTLOOK...EARLY MORNING FOG/STRATUS POSSIBLE TUESDAY AND
WEDNESDAY. ISOLATED TO SCATTERED AFTN SHOWERS/T-STORMS EXPECTED
THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM MONDAY...OUTSIDE OF LIGHT N TO NW WINDS EARLY TODAY DUE
TO A LAND BREEZE...EXPECT SE TO S FLOW AT 10 KT OR LESS THROUGH THE
PERIOD. SEAS ARE EXPECTED TO RUN 2 TO 3 FT.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 AM MONDAY...TWIN CENTERED HIGH PRESSURE ON TUESDAY...ONE OFF
THE COAST AND THE OTHER OVER THE MOUNTAINS. RESULTING FLOW ACROSS
THE WATERS WILL BE QUITE LIGHT AND SOMEWHAT VARIABLE ALTHOUGH A
PREDOMINANTLY SOUTHERLY COMPONENT WILL BE PRESENT. THE OVER LAND
HIGH WILL BE SHRINKING ON WEDNESDAY WITH LITTLE EFFECT ON LOCAL
WINDS AND THE CONTINUED DIMINUTIVE SEAS.
LONG TERM /THURSDAY THROUGH FRIDAY/...
AS OF 3 AM MONDAY...HIGH PRESSURE OVER THE LANDMASS/EASTERN U.S.
DURING THE SHORT TERM FINALLY WASHES OUT ENOUGH TO BRING A MORE
SEASONABLE SW FLOW ON THURSDAY AROUND THE WEST ATLANTIC HIGH. THIS
FLOW CONTINUES INTO FRIDAY BUT MAY BE EQUALLY BORNE OF PIEDMONT
TROUGHINESS AS THE WEAKENING WEST ATLANTIC RIDGE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MBB
NEAR TERM...RAN
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...BJR/31
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
210 AM EDT MON AUG 19 2013
.SYNOPSIS...
A DECAYING FRONTAL BOUNDARY WILL SLOWLY DISSIPATE ACROSS THE AREA
AS A WESTERN ATLANTIC RIDGE BUILDS TOWARD THE COAST. TEMPERATURES
MORE TYPICAL OF AUGUST WILL RETURN MUCH OF THIS UPCOMING WEEK WITH
A FEW AFTERNOON THUNDERSTORMS.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
AS OF 1045 PM SUNDAY...LATEST SAT IMAGERY CONTINUES TO SHOW THE
MOISTURE PLUME EXTENDING ALONG AND JUST EAST OF THE SPINE OF THE
APPALACHIANS...FROM THE FLORIDA PAN HANDLE TO THE NE STATES. FLOW
AROUND THE WESTERN ATLANTIC RIDGE HAS MUSCLED ITS WAY ACROSS THE
COASTAL CAROLINAS...AND THUS PREVENTING THIS MOISTURE PLUME FROM
ENCOMPASSING THE ENTIRE CWA TONIGHT INTO MONDAY. LATEST SREF
INDICATES A LOW PROBABILITY FOR MEASURE-ABLE RAIN TONIGHT...AND
HIGHLIGHTS 2 LOCATIONS...THE WESTERN FRINGES OF THE FA...AND
ACROSS THE IMMEDIATE COAST FROM ANY ONSHORE MOVEMENT OF PCPN. LOOK
FOR A RANGE OF 15 TO 40 POPS ACROSS THE FA OVERNIGHT. EARLIER
INCREASE TO THE MIN TEMPS TONIGHTS REMAINS ON TARGET...NO
ADDITIONAL TWEAKING NEEDED. WITH ONSHORE FLOW ACROSS 80+ DEGREE
SSTS...MIN TEMPS ALONG THE IMMEDIATE BEACHES MAY STAY IN THE UPPER
70S TO AROUND 80.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
AS OF 3 PM SUNDAY...PRIMARY WEATHER STORY MONDAY AND TUESDAY WILL
BE THE RETURN OF MORE TYPICAL AUGUST WEATHER ACROSS THE FORECAST
AREA...AS REMNANTS OF AN UNSEASONABLE FRONTAL BOUNDARY THAT
BROUGHT MINIMUM TEMPERATURES WELL INTO THE 60S AND HEARTY RAINFALL
AMOUNTS RECENTLY...LOSES IDENTITY AND DISSIPATES OVER THE AREA.
AN UPPER TROUGH PRESENTLY OVER THE MISSISSIPPI VALLEY WILL LIFT
NE AND DAMPEN ACROSS NEW ENGLAND BY MONDAY NIGHT. THIS WILL ALLOW
THE WESTERN EXTENT OF A STACKED BERMUDA RIDGE TO POKE LANDWARD
ACROSS THE SE US COAST MONDAY AND TUESDAY. LINGERING LOW AND MID
LEVEL MOISTURE ON MONDAY COUPLED WITH A WEAK COASTAL TROUGH MOVING
INLAND SHOULD TRIGGER SCATTERED SHOWERS AND ISOLATED TSTMS DURING
THE DAY ON MONDAY. BY TUESDAY HOWEVER...THE EFFECTS OF THE BERMUDA
RIDGE PROGRESSING INLAND...WILL BE SEEN BY DRYING IN THE MIDDLE
LEVELS OF THE ATMOSPHERE. WHILE WE CANNOT RULE OUT SHOWERS ON
TUESDAY...COVERAGE SHOULD BE SUBSTANTIALLY HINDERED BY SUBSIDENT
DRYING ALOFT.
WE MAY SEE LOW CLOUDS EARLY MONDAY AS WELL AS CONVECTIVE DEBRIS
CLOUDS DURING THE DAY...SO FOR MAXIMUMS AM EXPECTING MIDDLE AND
UPPER 80S ACROSS THE REGION. EFFECTS OF THE RIDGE TUESDAY SHOULD
ALLOW UPPER 80S MOST LOCATIONS WITH A FEW 90S ACROSS THE INTERIOR.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 3 PM SUNDAY...THE 500 MB UPPER LEVEL RIDGE AXIS IS STILL
TRYING TO TO BUILD WESTWARD AND WILL BE ALIGNED ALONG A LINE FROM
MOBILE TO SAVANNAH ON THURSDAY. THE 12 UTC CYCLE OF THE GFS DEVELOPS
A SECOND CUTOFF LOW SOUTH OF LAKE MICHIGAN ON WEDNESDAY AND LIFTS
THIS FEATURE WELL NORTH OF THE AREA BY LATE THURSDAY. ALOFT A TROUGH
IS CENTERED ALONG THE COAST AND NORTHWEST FLOW ALOFT WILL BE
ESTABLISHED. THE GFS IS SHOWING AN UPPER LEVEL DISTURBANCE SHIFTING
INTO THE CAROLINA BY THE END OF THE WEEK.
AT THE SURFACE THE FRONTAL BOUNDARY WILL REMAIN AND THE MODELS
CONTINUE TO SHOW A WEAKNESS IN THE SURFACE PRESSURE PATTERN THROUGH
FRIDAY. PRECIPITABLE WATERS WILL REMAIN HIGH AND THE ONLY UPPER
LEVEL SUPPORT MAY BE FROM SHORTWAVE IN THE NORTHWEST FLOW BY FRIDAY.
THE UNCERTAINTY IS HOW MUCH IMPACT THESE DISTURBANCES WILL HAVE ON
THE COAST. SO WITH THE CONFIDENCE NOT HIGH WENT WITH A CHANCE OF
DIURNAL CONVECTION EACH DAY AND ONLY A SLIGHT CHANCE OVERNIGHT.
MAXIMUM TEMPERATURES ARE EXPECTED TO BE NEAR 90 EACH DAY AND LOWS
IN THE LOWER 70S INLAND AND MID 70S AT THE BEACHES.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 06Z...SURFACE DEWPOINTS IN THE LOW TO MID 70S WITH CALM/LIGHT
WINDS SUGGEST THE LOW-LEVEL CONDITIONS ARE PRIMED FOR FOG/STRATUS
OVERNIGHT. MVFR CIGS/VSBYS ARE EXPECTED AT THE COASTAL TERMS...WITH
PERHAPS SOME BRIEF IFR VSBYS AT FOG-PRONE KCRE. KFLO/KLBT HAVE THE
BEST CHANCES FOR IFR...AS THE LATEST GUIDANCE FAVORS STRATUS
DEVELOPING AROUND DAYBREAK AT THE INLAND SITES. THE LATEST HRRR RUNS
SHOW SOME SHOWERS MOVING ONSHORE IN THE EARLY MORNING HOURS...SO
HAVE MENTIONED PCPN FOR THE COASTAL SITES AS WELL. CURRENT SHOWER
ACTIVITY INLAND HAS A CHANCE TO AFFECT THE INLAND TERMINALS THROUGH
ABOUT 09Z...PARTICULARLY FLO. MORE WIDELY SCATTERED SHOWERS ARE
EXPECTED WITH DAYTIME HEATING AS A COASTAL TROUGH WILL BE POSITIONED
OVER THE CAROLINAS. CIGS MAY BOUNCE AROUND BETWEEN VFR AND MVFR
DURING THE DAY...WITH MVFR MORE LIKELY DURING PERIODS OF SHRA.
SLIGHTLY HIGHER POPS INLAND ARE REFLECTED IN THE TAFS. CALM TO LIGHT
WINDS WILL BECOME S-SE AOB 10 KTS AT KMYR...KCRE AND KILM IN THE
AFTN HOURS.
EXTENDED OUTLOOK...EARLY MORNING FOG/STRATUS POSSIBLE TUESDAY AND
WEDNESDAY. ISOLATED TO SCATTERED AFTN SHOWERS/T-STORMS EXPECTED
THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1045 PM SUNDAY...THE INVERTED SFC TROF OR COASTAL FRONTAL
BOUNDARY...REMAINS STATIONARY ALONG THE IMMEDIATE COAST OF THE
CAROLINAS FROM CAPE HATTERAS SOUTHWARD. OVERALL...MODELS INDICATE
THE SFC PRESSURE PATTERN WILL YIELD AN E-SE WIND OVERNIGHT. THE
NEAR-SHORE WATERS...SAY WITHIN 5 NM FROM THE COAST...MAY OBSERVE
A NE WIND DIRECTION DURING THE MON PRE-DAWN HOURS. A RATHER
RELAXED SFC PG WILL YIELD 10 KT OR LESS FOR SPEEDS. SIGNIFICANT
SEAS GENERALLY AROUND 2 FT...EXCEPTION...ACROSS THE ILM SC WATERS
WHERE AN ESE GROUNDSWELL..ALBEIT SMALL AND AT 9-10 SECOND
PERIODS...COULD PUSH SIGNIFICANT SEAS UP TO 3 FEET. THIS GROUND
SWELL IS COMPLEMENTS OF THE SOUTHERN PERIPHERY FETCH OF THE WESTERN
ATLANTIC HIGH.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 3 PM SUNDAY...MARINE REGIME MONDAY AND TUESDAY WILL SEE THE SW
PORTION OF AN EXPANDING BERMUDA HIGH PRESSURE CELL MOVING ONTO THE
COAST...WHILE A WEAK SURFACE COASTAL TROUGH PUSHES INLAND. THIS
SHOULD IMPART A LIGHT S-SE WIND FLOW ACROSS THE 0-20NM WATERS. SEAS
2-3 FEET MOST AREAS...COMPOSED PRIMARILY OF SE WAVES EVERY 8-10
SECONDS WITH A LIGHT SOUTHERLY CHOP. WE MAY SEE A FEW SHOWERS AND
TSTMS OVER THE WATERS EARLY MONDAY AS CONVERGENCE INCREASES IN
RESPONSE TO THE COASTAL TROUGH ALONG THE COAST. NOT A BAD IDEA
A GET A RADAR FIX MONDAY MORNING BEFORE HEADING OUT.
LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 3 PM SUNDAY...THE FRONTAL BOUNDARY ALONG THE COAST CONTINUES
THROUGH THE FIRST PART OF THIS FORECAST PERIOD. WITH A VERY WEAK
PRESSURE GRADIENT EXPECTED WINDS WILL BE BE LESS THAN 10 KNOTS AND
VARIABLE THROUGH THURSDAY MORNING. THE LOCAL WAVE MODEL COUPLED
WITH THE WAVEWATCH III MODEL IS SHOWING SEAS AROUND 2 FEET THROUGH
THURSDAY MORNING AND A SLIGHT INCREASE IN SEAS TO 2 TO 3 FEET BY
LATE THURSDAY INTO FRIDAY AS A MORE SOUTH TO SOUTHWEST FLOW OF 10
KNOTS BECOMES ESTABLISHED.
&&
.TIDES/COASTAL FLOODING...
AS OF 1045 PM SUNDAY...THE TIDE GAGE ALONG THE CAPE FEAR RIVER
PEAKED AT 5.74 FT MLLW AT HIGH TIDE THIS EVENING...ABOVE THE 5.50
FT MLLW MINOR COASTAL FLOODING THRESHOLD. THE GAGE READING IS NOW
BELOW 5 FT MLLW AND CONTINUING TO DECLINE. WILL HAVE ANOTHER RUN
AT BREACHING MINOR COASTAL FLOODING THRESHOLDS DURING MONDAY
EVENINGS HIGH TIDE...WHICH MAY REQUIRE ANOTHER COASTAL HAZARD
MESSAGE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MJC
NEAR TERM...DCH
SHORT TERM...MJC
LONG TERM...DRH
AVIATION...BJR/31
TIDES/COASTAL FLOODING...DCH
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
159 AM EDT MON AUG 19 2013
.SYNOPSIS...
SEVERAL WEAK WEATHER SYSTEMS WILL DRIFT SLOWLY THROUGH THE GREAT
LAKES FROM TONIGHT THROUGH MID-WEEK...AS TEMPERATURES AND
HUMIDITY CONTINUE TO SLOWLY INCREASE AT THE SAME TIME. NEITHER OF
THE DISTURBANCES IS EXPECTED TO BRING MUCH COVERAGE OF RAIN...BUT
THREATS FOR SHOWERS OR A FEW THUNDERSTORMS ON A LIMITED BASIS WILL
BE PRESENT TONIGHT INTO MONDAY MAINLY EAST OF I-71...AND ON
WEDNESDAY ESPECIALLY SOUTH OF I-70. IN BOTH CASES...MOST AREAS
WILL STAY DRY...WITH MUGGY AND WARM AFTERNOONS AND MILD NIGHTS WITH
LIGHT WINDS. ABOVE NORMAL TEMPERATURES WILL REMAIN ENTRENCHED
THROUGH THE WEEK INTO NEXT WEEKEND...AS A VERY TYPICAL LATE SUMMER
PATTERN REMAINS IN PLACE.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
UPDATED TONIGHT TO REMOVE ALL PRECIPITATION FOR THE OVERNIGHT
HOURS. WITH LOSS OF HEATING OF THE DAY AND WEAK FORCING
REMAINING...THERE IS ONLY SMALL CHANCE OF SHOWERS. ALSO ADJUSTED
SKY COVER FOR CURRENT TRENDS. NO OTHER SIGNIFICANT CHANGES WERE
MADE WITH THIS UPDATE.
AFTERNOON DISCUSSION FOLLOWS BELOW....
DISORGANIZED SHIELD OF VERY LIGHT
RAIN/SPRINKLES HAS BEEN PUSHING STEADILY NORTHEAST THROUGH THE
AFTERNOON UP THE SCIOTO RIVER VALLEY...IMMEDIATELY IN ADVANCE OF A
MID-LEVEL VORTICITY MAX SEEN SWIRLING BOTH ON VISIBLE SATELLITE
IMAGERY AND ON RADAR MOSAICS OVER NRN KENTUCKY. THIS IS NEAR THE
NOSE OF A NARROW 250MB JETLET /115KT/ THAT IS SHIFTING NORTHEAST
AND ALLOWING THE OPENING/SHEARING OF THE OLD CLOSED LOW THAT HAD
BEEN SPINNING WELL SOUTHWEST OF THE AREA THE PAST FEW DAYS. THE
MID/UPPER LEVEL SHORTWAVE TROUGH IS POSITIVELY TILTED...AND
WEAKENING WITH TIME...WITH DECREASING LARGE SCALE ASCENT AND VERY
WEAK SURFACE FEATURES UNDERNEATH. THE 18.18Z RAP HAD A NICE HANDLE
ON THE MID LEVEL VORT MAX DRIVING NORTHEAST THROUGH SCNTL OH...AND
CONTINUES TO LIFT THIS FEATURE OUT OF THE AREA THROUGH MID
EVENING...WITH THE SHIELD OF LIGHT RAIN/SPRINKLES LIKELY EXITING
THE AREA BY 00Z OR SO...IF IT DOESN/T FALL APART COMPLETELY BEFORE
THEN. MESOANALYSIS CURRENTLY /19Z/ SHOWS A FAIRLY NICE
DIFFERENTIAL HEATING ZONE /CAPE AXIS/ ON THE IMMEDIATE WEST SIDE
OF THE RAIN SHIELD...RUNNING FROM OWEN/GRANT COUNTIES UP THROUGH
THE WILMINGTON AREA TOWARDS CMH. VARIOUS AND SUNDRY CONVECTION
ALLOWING MODEL RUNS /3-4KM RESOLUTION/ HAVE TRIED TO DEVELOP
ISOLATED STORMS IN THIS CORRIDOR IN THE NEXT FEW HOURS UP THROUGH
ABOUT 02Z...SO WE ARE IN NO HURRY TO DECREASE/SHRINK RAIN CHANCES
WEST OR SOUTHWEST OF CURRENT RAIN SHIELD OVER SCNTL OH. WHILE
MLCAPE IS LARGELY WEAK /300-700 J/KG/...THE PASSING OF THE
MID/UPPER LEVEL PV ANOMALY ACROSS THIS AREA THROUGH THE NEXT FEW
HOURS MAY AGITATE THE WEAK BAROCLINIC ZONE FOR A STORM OR TWO.
LATER THIS EVENING/OVERNIGHT...ONE MORE SURGE /IF YOU CAN CALL IT
THAT - IT IS QUITE WEAK/ OF MOISTURE ADVECTION RIDES FROM ERN
TN/KY INTO CNTL/ERN OH AND MAY PROMOTE SOME -SHRA REGENERATION
OVER THE SCIOTO VALLEY AND UP TOWARD/EAST OF CMH...SO WE HOLD ON
TO HIGHER RAIN CHANCES HERE LATER THIS EVENING AND OVERNIGHT. NOT
SURE IF THIS WILL LEAD TO MUCH ACTIVITY OR NOT...CONFIDENCE IS
LOW...BUT THE SIGNAL HAS BEEN PRESENT FOR A FEW DAYS THUS DON/T
WANT TO BACK AWAY YET. KEPT MIN TEMP FORECAST RIGHT WHERE IT WAS
FOR THE MOST PART...WELL TRENDED IN THE LOWER 60S MOST
AREAS...THOUGH MIXED OUT DEW POINTS IN WCNTL OHIO/ERN IND SUGGEST
SOME MID TO UPPER 50S IN THAT AREA WHERE PRECIPITABLE WATER
MINIMUM EXISTS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
THE LAST WEAK SURGE OF MOISTURE MAY LINGER SHOWER CHANCES IN THE
EAST IN THE MORNING...AND THERE MAY BE JUST ENOUGH DIURNAL INSTBY
FOR A SHOWER/STORM IN THE FAR EAST/SOUTH IN THE AFTERNOON...BUT
MONDAY IS LARGELY A DRY DAY FOR THE FORECAST AREA WITH INCREASING
SUBSIDENCE IN THE WAKE OF THE DEPARTING SHORTWAVE TROUGH WHICH
WILL BE SHEARING DOWNSTREAM THROUGH PA/NY. DESPITE ITS
DEPARTURE...THERE REMAINS A WEAKNESS IN THE LARGER SCALE HEIGHT
FIELD BETWEEN TWO LARGE ANTICYCLONES OFF THE SOUTHEAST CONUS AND
OVER THE CNTL CONUS. THIS WEAKNESS IS A SOURCE OF LINGERING WEAK
SHORTWAVE ENERGY...AND WITH THIS AXIS LINGERING IN THE FAR
SOUTH/EAST...THUS THE SMALL RAIN CHANCES LINGERING UNTIL THAT AXIS
CAN CLEAR IN THE MID AFTERNOON HOURS. MOST AREAS WILL SEE A FAIR
AMOUNT OF SUNSHINE ON MONDAY...WITH TEMPS ADDING A FEW MORE
DEGREES TO PUT MOST AREAS IN THE LOW-MID 80S.
BRIEF SHORTWAVE RIDGING SLIDES IN FOR MONDAY NIGHT...WITH SKIES
GOING CLEAR. THIS SHOULD ALLOW A LITTLE BETTER TEMP DROP WITH
PWAT DROPPING OFF BACK TOWARD 1 INCH /BELOW SEASONAL NORMS/.
THUS...SIDED WITH SOME OF THE MOS DATASETS THAT ALLOWED COOL SPOTS
TO DROP OFF PRETTY DECENTLY MON NIGHT INTO THE UPPER 50S. WITH
SUCH LIGHT WINDS OVER THE NEXT COUPLE NIGHTS...ALMOST CERTAIN TO
BE COMMON SUMMER NIGHT FOG IN LOW LYING AREAS...BUT NOT SEEING A
GREAT SIGNAL FOR SOMETHING WIDESPREAD TO INCLUDE IN THE FORECAST
AS OF YET.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
SURFACE HIGH PRESSURE WILL ESTABLISH ITSELF TO OUR SE ON TUESDAY IN
WAKE OF DEPARTING UPR LVL SYSTEM. WE SHOULD SEE A MOSTLY SUNNY TO
PARTLY SUNNY DAY. MODELS HAD BEEN SUGGESTING THAT PERHAPS A POP OF
SHOWER OR STORM COULD OCCUR IN THE FAR SOUTH DURING THE HEAT OF THE
DAY. THIS STILL MAY OCCUR...BUT DO NOT FEEL IT WARRANTS A 20 POP
MENTION SO HAVE ALLOW THE FORECAST TO REMAIN DRY. HIGHS WILL BE A
LITTLE WARMER...GENERALLY IN THE MID 80S.
FOR THE PERIOD TUESDAY NIGHT INTO WEDNESDAY NIGHT...MAJORITY OF
MODELS HAVE COME MORE IN LINE ON WHAT WILL HAPPEN TO EMBEDDED S/WV
ENERGY WITHIN THE NW FLOW ALOFT. IT APPEARS THIS ENERGY WILL DEVELOP
INTO A CLOSED LOW TO OUR WEST...THEN WILL SLOWLY PROGRESS EAST THROUGH
THE REGION WEDNESDAY INTO WEDNESDAY NIGHT. ECMWF/GFS SUGGEST THAT
SOME EMBEDDED S/WV ENERGY MOVING NE AROUND DEVELOPING CLOSED LOW
COULD SPARK A FEW SHOWERS AND THUNDERSTORMS BEGINNING ACRS OUR SW
TUESDAY NIGHT. HAVE GIVEN ALL LOCATIONS AT LEAST A THREAT FOR
SHOWERS AND STORMS ON WEDNESDAY WITH THE HIGHER CHANCES FAVORING THE
SRN ZONES DUE TO HIGHER INSTABILITY AND MOISTURE. HAVE ALLOWED POPS
TO FALL OFF OVERNIGHT WEDNESDAY NIGHT AS SYSTEM HEADS EAST. HIGHS ON
WEDNESDAY WILL BE SLIGHTLY COOLER...ESPECIALLY SOUTHWEST CLOSER TO
THE UPR LVL LOW.
FOR THE PERIOD THURSDAY INTO FRIDAY NIGHT...MODELS CONTINUE TO
STRUGGLE ON HOW LONG WAVE TROUGH ENERGY WILL DIG SE INTO SE CANADA
AND NEW ENGLAND DURING THE PERIOD. AS SUCH...ASSOCIATED COLD FRONT
AND WHERE IT WILL END UP...I.E. WILL IT PUSH THROUGH...STALL OUT
OVER OUR AREA...OR PERHAPS FALL APART...IS STILL IN QUESTION. HAVE
TAKEN A BLEND OF WPC AND THE LATEST 18.12Z ECMWF...WHICH ALLOWS THE
FRONT TO APPROACH THE REGION FROM THE NORTH THURSDAY NIGHT...SLOW IT
UP AS IT PUSHES INTO THE REMAINDER OF THE AREA ON FRIDAY...THEN
WASHES IT OUT FRIDAY NIGHT INTO SATURDAY AS ANOTHER HIGH PRESSURE
RIDGE BUILDS IN FROM THE NORTH. GIVEN LACK OF STRONG UPR
SUPPORT...AS IT IS FCST TO REMAIN WELL OFF TO THE NE...ALONG WITH
WEAK LOW LEVEL FORCING...HAVE KEPT POPS LOW THURSDAY NIGHT INTO
FRIDAY. HAVE THEN ALLOWED CONDITIONS TO DRY OUT BY FRIDAY NIGHT.
TEMPERATURES WILL BE CLOUD DEPENDENT BUT SHOULD SEE A SLIGHT BUMP UP
AHEAD OF THE FRONT ON THURSDAY WITH SIMILAR OR SLIGHTLY COOLER
CONDITIONS POSSIBLE ON FRIDAY.
SURFACE HIGH PRESSURE WILL MOVE EAST THROUGH THE UPCOMING WEEKEND AS
A MID LVL RIDGE BEGINS TO NUDGE INTO FROM THE CNTRL PLAINS.
CONDITIONS SHOULD REMAIN DRY. TEMPERATURES WILL BE SEASONABLY WARM
FOR LATE AUGUST.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
FOG AND IN SOME INSTANCES LOW CIGS HAVE DEVELOPED ACROSS THE AREA
AND WILL CONTINUE THROUGH THE OVERNIGHT HOURS. EXPECT VSBYS TO
FLUCTUATE THROUGH THE NIGHT HOWEVER CONDITIONS WILL IMPROVE
SHORTLY AFTER SUNRISE. WINDS WILL BE LESS THAN 10 KNOTS THROUGH
THE TAF PERIOD. ADDITIONAL FOG WILL BE POSSIBLE MONDAY NIGHT AS
WELL.
OUTLOOK...FOG WILL BE POSSIBLE MONDAY NIGHT. THUNDERSTORMS ARE
POSSIBLE ON WEDNESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...BINAU
NEAR TERM...BINAU/PARKER
SHORT TERM...BINAU
LONG TERM...HICKMAN
AVIATION...NOVAK
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
156 AM EDT MON AUG 19 2013
.SYNOPSIS...
A WEAK DISTURBANCE WILL PASS ACROSS PA TODAY...BRINGING CLOUDS
AND SOME RAIN. HIGH PRESSURE CENTERED NEAR BERMUDA WILL CONTROL
THE WEATHER ACROSS PA DURING MIDWEEK...DELIVERING WARMER AND MORE
HUMID CONDITIONS BEFORE A COLD FRONT ARRIVES AROUND FRIDAY.
&&
.NEAR TERM /UNTIL 8 AM THIS MORNING/...
UPPER LVL TROUGH LIFTING NE THRU THE OHIO VALLEY THIS AM. LG SCALE
FORCING AHEAD OF THIS FEATURE IS RESULTING IN A FEW -SHRA ACROSS
WESTERN PA AS OF 05Z AND EXPECT SCT -SHRA TO MOVE INTO THE
ALLEGHENIES AND CENTRAL MTNS BY 12Z. CLOUD COVER AND INCREASING
LOW LVL MOISTURE SHOULD KEEP TEMPS FROM FALLING MUCH FROM 05Z
READINGS WITH LOWS IN THE M-U50S.
&&
.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM TUESDAY/...
SLOW MOVING UPPER TROF WILL TAP 1.5" PW FOR MORE WIDESPREAD CHC
OF SHOWERS AND TSTORMS ACROSS MOST AREAS ON MONDAY. PASSAGE OF
UPPER TROF AXIS WILL BRING A DECREASING CHC OF SHOWERS ACROSS THE
WESTERN COUNTIES DURING MID TO LATE AFTN. A GOOD DEAL OF CLOUD
COVER SHOULD LIMIT CAPES...SO SEVERE WEATHER IS NOT EXPECTED.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
INTERESTING LOW OFF NORFOLK VA THIS AFT...STARTING TO PULL AREA
OF SHOWERS EAST OF THE AREA THIS AFT...BUT MORE SHOWERS ACROSS
THE OH VLY WITH THE UPPER LVL LOW.
EXPECT SHOWERS TO LINGER INTO MONDAY...BEFORE CONDITIONS IMPROVE
LATE. AFTER THIS...MAINLY DRY EXPECT FOR LATER THU INTO FRIDAY...
WHEN A COLD FRONT MOVES ACROSS PA. SOME RISK OF SHOWERS ON WED
ACROSS THE SE LIKE TODAY...BUT LEFT OUT FOR NOW. OVERALL A
COMPLEX PATTERN...WITH THE TENDENCY FOR MORE STABLE AND LESS
HUMID AIR TO TRY TO BUILD SOUTHWARD EAST OF THE MOUNTAINS...
GIVEN HIGH OVER EASTERN CANADA AND NEW ENGLAND THIS WEEK. AT
THE SAME TIME...WARMER AND MORE HUMID AIR WORKS NORTHWARD
WEST OF THE MOUNTAINS. FOR NOW...LEFT MAX TEMPS CLOSE TO WHAT
WAS IN THE GRIDS. REAL STRONG WARM ADVECTION WITH STRONG
WESTERLY FLOW WILL BE WELL NORTH OF THE US...CANADIAN BORDER
FROM LATE TUE INTO EARLY THU.
MAIN CHANGE WAS TO UP MIN TEMPS MONDAY NIGHT AND TUE NIGHT...GIVEN
GUIDANCE AND OTHER OFFICES.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
VERY SUBTLE FEATURES DRIVING THE FORECAST FOR THE NEXT 24
HOURS...AND THEREFORE FORECAST IS OF SOMEWHAT LOWER CONFIDENCE.
VERY LITTLE PRECIPITATION REMAINS ON RADAR...AS WESTERN PA
ACTIVITY HAS DWINDLED TO JUST A FEW SCATTERED SHOWERS. SHORT RANGE
MODELS CONTINUE TO SUPPORT THE IDEA OF SHOWERS REDEVELOPING
OVERNIGHT ACROSS THE WEST...AND SPREADING INTO CENTRAL PA BY
MORNING. RUC ALSO CONTINUES THE THINKING OF DEVELOPING SCATTERED
CONVECTION ACROSS CENTRAL AREAS TOMORROW AFTERNOON...PROPAGATING
TO THE SOUTH AND EAST.
HOWEVER...BASED ON RADAR TRENDS...HAVE CUT BACK ON PRECIPITATION
IN MOST TAFS OVERNIGHT. FOG AND LOWER STRATUS FORECAST BY MODELS
ALSO SLOWER THAN EXPECTED IN PREVIOUS FORECAST...WITH ALL
LOCATIONS AT 03Z STILL VFR. WILL CONTINUE THE THINKING ALONG THE
LINES OF LOWER CLOUDS AND FOG FORMATION...BUT HAVE BACKED OFF A
BIT ON LOWER LIMITS OF RESTRICTIONS.
UPPER TROF AXIS LIFTS NORTHEAST MONDAY. RESULT WILL BE SLIGHT
SURFACE RIDGING DEVELOPING DURING THE DAY AND A SUBTLE/GRADUAL
WIND SHIFT TO THE WEST DURING THE AFTERNOON. HOWEVER...REMNANTS OF
UPPER TROF MOVING THROUGH THE REGION COULD DEVELOP SOME CONVECTION.
WITHOUT A REAL PUSH OF DRIER AIR...EXPECT MORE FOG FORMATION
MONDAY NIGHT INTO TUESDAY...BEFORE A RETURN TO VFR BY MID WEEK.
OUTLOOK...
MON...AM MVFR/IFR...WITH IMPROVEMENTS DURING THE AFTERNOON MOST
LOCATIONS. ADDITIONALLY...SCATTERED SHOWERS AND ISOLATED TSRA.
TUE...AM FOG POSS. THEN MAINLY VFR.
WED-THU...VFR.
FRI...MVFR WITH SCT SHRA/TSRA.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...FITZGERALD
SHORT TERM...DEVOIR/FITZGERALD
LONG TERM...MARTIN
AVIATION...JUNG
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
327 AM CDT MON AUG 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 327 AM CDT MON AUG 19 2013
THE MAIN FOCUS FOR TODAY IS ON A MID LEVEL TROUGH THAT WILL COME
THROUGH AND WHETHER IT WILL HAVE ENOUGH LIFT TO OVERCOME THE DRY
LOW LEVEL AIR AND PRODUCE SOME RAIN SHOWERS.
THIS MID LEVEL TROUGH IS CURRENTLY ANALYZED VIA WATER VAPOR IR AND
19.06Z RAP 500MB ANALYSIS FROM SOUTHWESTERN ONTARIO THROUGH
MINNESOTA AND EASTERN NEBRASKA. SOME VERY HIGH BASED RADAR RETURNS
HAVE BEEN SHOWING UP ACROSS EASTERN SOUTH DAKOTA AND WESTERN
MINNESOTA THOUGH THERE HAVE NOT BEEN MANY SIGHTS REPORTING THAT
THE RAIN IS REACHING THE GROUND. THIS IS ALSO IN A BELT OF HIGHER
LOW LEVEL MOISTURE TRANSPORT THAT IS TRAPPED UNDER A 700MB
INVERSION...BUT IS HELPING TO RAISE SURFACE DEW POINTS. THIS IN
TURN HAS CREATED A MORE UNSTABLE AIR MASS FROM THE DAKOTAS UP INTO
NORTHERN MINNESOTA. THE 19.07Z RAP KEEPS MUCH OF THIS MOISTURE
TRANSPORT AND HIGHER INSTABILITY OUT TO THE WEST TODAY...SO THIS
TROUGH WILL BE ENTERING AN ENVIRONMENT THAT IS LESS FAVORABLE TO
SEE THE SHOWERS CONTINUE. CONSIDERED PUTTING IN A MENTION OF
SPRINKLES TODAY IN FOR SOUTHEAST MINNESOTA AND WESTERN TO NORTH
CENTRAL WISCONSIN...BUT HELD OFF FOR THE TIME BEING SINCE
REFLECTIVITIES OUT WEST APPEAR TO BE ON A WEAKENING TREND.
MID TO HIGH LEVEL CLOUD COVER WILL BE FAIRLY WIDESPREAD FOR A
PORTION OF THE DAY WHICH WILL KEEP TEMPERATURES DOWN A LITTLE BIT.
THE 19.00Z NAM/GFS SHOW SOME WARMER 850/925MB AIR MOVING IN THIS
AFTERNOON AS SOME OF THIS CLOUD COVER EXITS. EXPECT THAT WE WILL
WARM UP PRETTY QUICKLY AS THIS OCCURS...BUT PERHAPS NOT AS HIGH AS
PREVIOUSLY ADVERTISED.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 327 AM CDT MON AUG 19 2013
CONDITIONS WILL CONTINUE TO WARM INTO MID WEEK AHEAD OF A COLD
FRONT/TROUGH THAT WILL PROPAGATE INTO THE REGION ON WEDNESDAY.
WEDNESDAY IS EXPECTED TO BE THE WARMEST DAY OF THE WEEK WITH LOW
LEVEL WARM AIR ADVECTION BUMPING 925MB TEMPERATURES UP TO AROUND
26C AND 850MB TEMPERATURES TO 20C. THIS WARM LAYER SHOULD ALSO
HELP TO KEEP THE WARM SECTOR CAPPED OFF UNTIL THE COLD FRONT DROPS
DOWN LATE WEDNESDAY AFTERNOON AND EVENING. THE AIR MASS WILL
BECOME UNSTABLE WITH MODIFIED 19.00Z NAM/GFS SOUNDINGS...MODIFIED
FOR LOWER DEW POINTS IN THE MID/UPPER 60S...SHOWING BETWEEN
1500-2500 J/KG OF 0-3KM MUCAPE ALONG A NARROW CORRIDOR JUST AHEAD
OF THE FRONT. WIND SHEAR LOOKS MARGINAL WITH THE BETTER DEEP SHEAR
IN CENTRAL MINNESOTA/NORTHERN WISCONSIN WHERE 500MB WINDS WILL BE
AROUND 40KTS DUE TO THE MID LEVEL SHORT WAVE TROUGH DROPPING INTO
THE NORTHERN GREAT LAKES. FURTHER SOUTHWEST ALONG THE FRONT CLOSER
TO SOUTHERN MINNESOTA AND NORTHERN IOWA...19.00Z NAM/GFS
SOUNDINGS/HODOGRAPHS DO SHOW SOME DIRECTIONAL/SPEED SHEAR IN THE
LOWEST 2KM WHICH WOULD BE MORE FAVORABLE FOR STRONGER WINDS. BASED
ON THE INSTABILITY AND SHEAR...IT APPEARS THAT LARGE HAIL AND
DAMAGING WINDS STILL APPEAR TO BE THE MAIN THREATS IN THE LATE
AFTERNOON INTO THE EVENING...PARTICULARLY ACROSS SOUTHEAST
MINNESOTA...WESTERN WISCONSIN AND NORTHEAST IOWA.
THE ISSUE THEN CONTINUES TO BE WITH HOW FAR SOUTH WILL THE COLD
FRONT MAKE IT AND THEN HOW FAST DOES IT GET PUSHED BACK TO THE
NORTH AS A WARM FRONT BY THE END OF THE WEEK. THE ECMWF HAS
TRENDED TOWARD WHAT THE GFS/GEM HAVE BEEN ADVERTISING THE PAST FEW
DAYS WITH HAVING THE FRONT DROP SOUTH INTO IOWA/NORTHERN ILLINOIS
BY THURSDAY MORNING...BUT THE 19.00Z ECMWF STILL REMAINS THE
FURTHEST NORTH WITH WHERE IT STALLS OUT. THERE ALSO IS BETTER
CONTINUITY WITH THE NEXT TROUGH TRACKING ACROSS THE NORTHERN
PLAINS ON FRIDAY INTO SATURDAY WHICH IS WHEN THE FRONT COMES BACK
NORTH AS A WARM FRONT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1100 PM CDT SUN AUG 18 2013
A TIGHTENING PRESSURE GRADIENT IN PLACE THIS MORNING WILL HELP TO
PRODUCE A DEEPER AND STRONGER LAYER OF WINDS...WITH SPEEDS OF
10-20 KTS FROM JUST RIGHT ABOVE THE SURFACE TO 5000 FT. THESE
WINDS COMBINED WITH SOME PASSING CIRRUS SHOULD HELP KEEP RIVER
VALLEY FOG TO A MINIMUM. HOWEVER...HAVE LEFT THE MVFR VISIBILITIES
AND THE POTENTIAL FOR A SCATTERED 400 FT STRATUS DECK TO DEVELOP
ALONG THE CHANNEL. IF WINDS DO NOT INCREASE AS FORECAST...
VISIBILITIES AND CEILINGS COULD END UP A LOT LOWER. OTHERWISE...
SCATTERED TO BROKEN HIGH LEVEL CLOUDS ASSOCIATED WITH A PASSING
WEATHER SYSTEM TO THE NORTH WILL SPILL OVER THE TAF SITES.
AFTERNOON CUMULUS WITH BASES BETWEEN 4 AND 5 KFT LIKELY AS WELL.
MODEL SOUNDINGS SHOW MORE MIXING...ESPECIALLY ACROSS THE OPEN
AREAS OF MINNESOTA...RESULTING IN THE NEED FOR GUSTS AT KRST FOR
THE AFTERNOON. PLAN ON WINDS TO DIMINISH IN THE EVENING WITH LOSS
OF HEATING...ALONG WITH CLEARING SKIES.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...ZT/AJ
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1128 PM CDT SUN AUG 18 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND MONDAY
ISSUED AT 256 PM CDT SUN AUG 18 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
CENTERED OVER THE NE U.S...BUT WITH A RIDGE AXIS THAT EXTENDS WEST
INTO THE GREAT LAKES. THE MAIN STORM TRACK REMAINS NORTH OF THE
REGION OVER SOUTHERN CANADA...BUT IS GRADUALLY SINKING TO THE
SOUTH. AS THIS OCCURS...A SHORTWAVE OVER EASTERN MONTANA IS MOVING
EAST AND PRODUCING THUNDERSTORMS...WHICH WILL TRACK TOWARDS THE
REGION TOMORROW. BESIDES TEMPERATURES...SMALL THUNDERSTORM CHANCES
REMAIN THE MAIN FORECAST CONCERNS.
TONIGHT...THE SHORTWAVE TROUGH OVER EASTERN MONTANA WILL MOVE EAST
INTO THE NORTHERN MISSISSIPPI VALLEY BY 12Z MONDAY. THE 850MB
MOISTURE AND INSTABILITY AXES WILL SHIFT INTO NORTHEAST MINNESOTA BY
THIS TIME...WHICH LOOKS TOO FAR WEST FOR MUCH OF AN IMPACT ON THE
FORECAST AREA. OTHERWISE...SCATTERED HIGH CLOUDS WILL BE PASSING
OVERHEAD FOR MUCH OF NIGHT...AND THEN SEE THE HIGH CLOUDS THICKEN
AND LOWER A BIT LATE AS THE SHORTWAVE DRAWS CLOSER. THE PRESSURE
GRADIENT WILL BE TIGHTENING TONIGHT...WHICH SHOULD ALLOW A LIGHT SW
WIND TO PERSIST AND KEEP ANY FOG FROM FORMING. LOWS WILL CONTINUE
THEIR WARMING TREND...AND RESIDE IN THE 50S.
MONDAY...THE SHORTWAVE TROUGH WILL MOVE INTO WISCONSIN. FORCING
WITH THE WAVE APPEARS TO SUBTLY WEAKEN...SO WILL LIKELY NEED THE
HELP OF DIURNAL INSTABILITY TO GET CONVECTION GOING. THE MOISTURE
AXIS WILL BE SNEAKING INTO NORTH-CENTRAL WISCONSIN IN THE
AFTERNOON...BUT PROGGED NAM SOUNDINGS AT 21Z NEAR EAGLE RIVER SHOW
DECENT CAPPING CENTERED AT ABOUT 800 MB. USING A PARCEL OF
82/62...ML CAPES WILL REACH AROUND 1000 J/KG...WHILE CINS REMAIN A
ROBUST 70-80 J/KG. UNLESS THE CAP IS ADVERTISED TOO
STRONGLY...CANNOT SEE MORE THAN ISOLATED STORM DEVELOPMENT GIVEN THE
WEAK FORCING. IF STORMS DO DEVELOP...WEAK SHEAR ALOFT WILL KEEP THE
SEVERE THREAT RATHER LOW. MADE ONLY MINOR TWEAKS TO TIMING AND
COVERAGE OF POPS. DESPITE AN INCREASE IN CLOUD COVER...LOW LEVEL
TEMPS WILL ALSO BE WARMING...AND PUSH HIGHS INTO THE MIDDLE 80S.
.LONG TERM...MONDAY NIGHT THROUGH SUNDAY
ISSUED AT 256 PM CDT SUN AUG 18 2013
TUESDAY THROUGH NEXT WEEKEND WILL BE HIGHLIGHTED WITH ABOVE
NORMAL TEMPERATURES. THE NEXT MAIN CHANCE FOR WIDESPREAD
PRECIPITATION WILL BE STARTING WEDNESDAY AFTERNOON OVER NORTHWEST
WISCONSIN THEN OVER THE REST OF THE STATE WEDNESDAY NIGHT INTO
THURSDAY WITH THE PASSAGE OF A COLD FRONT.
THERE IS A SMALLER CHANCE OF CONVECTION ON TUESDAY OVER THE
NORTHWEST HALF OF THE STATE DUE TO CONTINUED WAA...AND IN A REGION
OF UPPER DIVERGENCE AHEAD OF THE WESTERLIES OVER THE NORTHERN
PLAINS. CONVECTION MAY BE CONFINED TOWARD WESTERN PORTION OF THE
STATE BUT WILL LEAVE PARTS OF NC WI WITH SMALL CHANCE DUE TO TOTAL
TOTALS INCREASE IN THE AFTERNOON.
THE WESTERLY FLOW OVER THE NORTHERN PLAINS BEGINS TO BUCKLE
WEDNESDAY AS A SHORT WAVE TROUGH DEVELOPS OVER SOUTHERN CANADA
AND A COLD FRONT SAGS INTO THE NORTHERN GREAT LAKES REGION
INCLUDING NORTHWEST WISCONSIN. MEDIUM RANGE MODELS ARE IN GOOD
AGREEMENT WITH THE TIMING OFF THIS FRONT AND CONVECTION UNTIL
WEDNESDAY NIGHT FOR MOST LOCATIONS EXCEPT NORTH CENTRAL WISCONSIN.
SEVERE POTENTIAL REMAINS FOR WEDNESDAY AFTERNOON INTO WEDNESDAY
NIGHT. TOTAL TOTALS CLIMB INTO THE LOWER 50S WITH THE FRONT WHILE
PWATS INCREASE TO NEAR 2.00
GFS...GEM DROP THE CONVECTION AND FRONT WELL SOUTH ON THURSDAY
FOR A DRIER TREND WHICH COULD LAST INTO FRIDAY. BUT THE ECMWF
SLOWS THIS FRONT DOWN WHILE A HIGH PRESSURE SYSTEM DRIFTS OVER
THE NORTHERN GREAT LAKES REGION THURSDAY THROUGH FRIDAY.
THE UPPER RIDGE CONTINUES TO BUILD INTO THE WEEKEND FOR MORE HEAT
ALONG WITH CHANCES OF CONVECTION ON THE PERIPHERY OF THE RIDGE OR
MAINLY THE NORTHERN GREAT LAKES REGION.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1125 PM CDT SUN AUG 18 2013
VFR CONDITIONS EXPECTED AS ANTICYCLONE SLOWLY SHIFTS SE OF THE
AREA. SHOULD SEE A LITTLE MORE GUSTINESS IN THE WINDS TOMORROW AS
FAIRLY DEEP MIXING IS EXPECTED TO OCCUR. CAN/T RULE OUT A SHRA/TSRA
ACRS THE N TOMORROW AFTN...BUT SUPPORT IS VERY LIMITED SO WL KEEP
THE TAFS DRY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
900 AM MDT MON AUG 19 2013
CORRECTION TO ADD MISSING WORD IN FIRST SENTENCE OF THE UPDATE
.UPDATE...
ISSUED AT 830 AM MDT MON AUG 19 2013
QUICK UPDATE TO THE GRIDDED FORECAST TO BETTER REFLECT THE CURRENT
SUNNY/MOSTLY SUNNY CONDITIONS ACROSS MOST OF FORECAST AREA EARLY
THIS MORNING. EXCEPTION IS SOME ALTOCUMULUS CLOUDS OVER SE UT LEFT
OVER FROM LAST NIGHT AND WHERE THE RAP MODEL PUTS A WEAK VORTICITY
MAX. CURRENT FORECAST FOR THIS AFTERNOON SEEMS ON TRACK PER QUICK
LOOK AT THE LATEST RAP/HRRR MODELS.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
300 AM MDT MON AUG 19 2013
HIGH PRESSURE WILL REMAIN ANCHORED OVER THE REGION FOR THE NEXT
SEVERAL DAYS. MOISTURE WORKING NORTHWARD WILL BRING ANOTHER ROUND
OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING...WITH THE
FOCUS TODAY GENERALLY SOUTH OF INTERSTATE 70. STORMS WILL
INITIALLY FIRE ALONG THE HIGHER TERRAIN...WITH ACTIVITY DRIFTING
OFF OVER THE VALLEYS LATE THIS AFTERNOON AND EVENING...WITH AN
EMPHASIS ON DRIFT. WINDS ALOFT WILL BE WEAK WITH THE RIDGE
DIRECTLY OVERHEAD AND POTENTIAL FOR LOCALLY HEAVY RAINFALL WILL BE
UP A BIT WITH SLOW STORM MOTIONS. TEMPERATURES WILL BE RUNNING
NEAR SEASONAL NORMS WITH LIGHT WINDS OUTSIDE OF CONVECTIVE GUSTS
TO NEAR 40 MPH WITH THE STRONGER STORMS.
A STRONGER SURGE OF SUBTROPICAL MOISTURE CONTINUES TO WORK INTO
THE GREAT BASIN AND THEN LEAKS EASTWARD INTO TUESDAY FOR AN UPTURN
IN SHOWERS AND THUNDERSTORMS. THE SHEARED ENERGY FROM THE BAJA
DISTURBANCE IS PROGGED TO STAY WELL WEST OF THIS CWA WITH TIME
HEIGHT SECTIONS SHOWING LITTLE ORGANIZED DYNAMICAL LIFT. STILL
PRECIPITABLE WATER VALUES CLIMB TO AN INCH OVER EASTERN UTAH AND
FAR WESTERN COLORADO. BROKEN TO OVERCAST SKIES MAY LIMIT OR DELAY
AFTERNOON HEATING AND INSTABILITY SOMEWHAT. SLOW STORM MOTION WILL
PRODUCE LOCALLY HEAVY RAIN AND POTENTIAL RUNOFF PROBLEMS. A
RELATIVELY DRY NEAR- SURFACE LAYER WILL ALSO ASSIST WITH ENHANCED
LOCAL OUTFLOW WINDS.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
300 AM MDT MON AUG 19 2013
BOUNDARY INTERACTION MAY PRODUCE ISOLATED NOCTURNAL CONVECTION
INTO WEDNESDAY MORNING. THE 593 HIGH REBOUNDS WESTWARD BACK TO
NEAR THE FOUR CORNERS. BOTH THE GFS AND NAM ERODE PRECIPITABLE
WATER VALUES SOMEWHAT UNDER THE HIGH. SUBSIDENCE WILL ALSO CAP
LATE DAY CONVECTION A BIT COMPARED TO TUESDAY. STILL ALL MTN
RANGES WILL LIKELY FIRE SOME AFTERNOON STORMS. STORM MOTION
REMAINS SLOW FOR A CONTINUED THREAT OF LOCALLY HEAVY SHOWERS.
MOISTURE WORKING NORTHWARD ALONG THE WESTERN EDGE OF HIGH PRESSURE
CENTERED ACROSS THE CENTRAL PLAINS WILL KEEP CONDITIONS UNSETTLED
AS WE MOVE THROUGH THE WEEK AND INTO THE WEEKEND. HARD TO PIN
POINT ANY INDIVIDUAL WAVE IN THIS PATTERN FOR ENHANCED
POTENTIAL...SO FOR NOW WILL CONTINUE WITH THE BROAD BRUSH APPROACH
OF DAILY CONVECTION...PRIMARILY FOCUSED ON THE AFTERNOON AND
EVENING HOURS. TEMPERATURES WILL BE RUNNING NEAR SEASONAL NORMS
THROUGH THE PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
300 AM MDT MON AUG 19 2013
SCATTERED SHOWERS AND THUNDERSTORMS WILL AGAIN DEVELOP ACROSS
EASTERN UTAH AND WESTERN COLORADO THIS AFTERNOON AND EVENING. THE
STORMS WILL BE MOST NUMEROUS SOUTH AND EAST OF A LINE FROM K4HV TO
KEGE...ESPECIALLY BETWEEN 20Z THIS AFTERNOON AND 03Z THIS EVENING.
OUTSIDE OF THIS WINDOW...STORMS WILL BE MORE ISOLATED IN NATURE.
EXPECT BRIEF HEAVY RAIN...SMALL HAIL AND GUSTY OUTFLOW WINDS TO
40 MPH IN THE VICINITY OF SHOWERS WITH BRIEF MOUNTAIN OBSCURATIONS
POSSIBLE. STORMS DISSIPATE AFTER 03Z THIS EVENING WITH VFR CONDS
PREVAILING AT ALL TERMINAL SITES.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
UPDATE...JAD
SHORT TERM...JDC/JOE
LONG TERM...JOE/JDC
AVIATION...JDC
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
837 AM MDT MON AUG 19 2013
.UPDATE...
ISSUED AT 830 AM MDT MON AUG 19 2013
QUICK UPDATE TO THE GRIDDED FORECAST TO BETTER REFLECT THE CURRENT
SUNNY/MOSTLY CONDITIONS ACROSS MOST OF FORECAST AREA EARLY THIS
MORNING. EXCEPTION IS SOME ALTOCUMULUS CLOUDS OVER SE UT LEFT OVER
FROM LAST NIGHT AND WHERE THE RAP MODEL PUTS A WEAK VORTICITY MAX.
CURRENT FORECAST FOR THIS AFTERNOON SEEMS ON TRACK PER QUICK LOOK
AT THE LATEST RAP/HRRR MODELS.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
300 AM MDT MON AUG 19 2013
HIGH PRESSURE WILL REMAIN ANCHORED OVER THE REGION FOR THE NEXT
SEVERAL DAYS. MOISTURE WORKING NORTHWARD WILL BRING ANOTHER ROUND
OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING...WITH THE
FOCUS TODAY GENERALLY SOUTH OF INTERSTATE 70. STORMS WILL
INITIALLY FIRE ALONG THE HIGHER TERRAIN...WITH ACTIVITY DRIFTING
OFF OVER THE VALLEYS LATE THIS AFTERNOON AND EVENING...WITH AN
EMPHASIS ON DRIFT. WINDS ALOFT WILL BE WEAK WITH THE RIDGE
DIRECTLY OVERHEAD AND POTENTIAL FOR LOCALLY HEAVY RAINFALL WILL BE
UP A BIT WITH SLOW STORM MOTIONS. TEMPERATURES WILL BE RUNNING
NEAR SEASONAL NORMS WITH LIGHT WINDS OUTSIDE OF CONVECTIVE GUSTS
TO NEAR 40 MPH WITH THE STRONGER STORMS.
A STRONGER SURGE OF SUBTROPICAL MOISTURE CONTINUES TO WORK INTO
THE GREAT BASIN AND THEN LEAKS EASTWARD INTO TUESDAY FOR AN UPTURN
IN SHOWERS AND THUNDERSTORMS. THE SHEARED ENERGY FROM THE BAJA
DISTURBANCE IS PROGGED TO STAY WELL WEST OF THIS CWA WITH TIME
HEIGHT SECTIONS SHOWING LITTLE ORGANIZED DYNAMICAL LIFT. STILL
PRECIPITABLE WATER VALUES CLIMB TO AN INCH OVER EASTERN UTAH AND
FAR WESTERN COLORADO. BROKEN TO OVERCAST SKIES MAY LIMIT OR DELAY
AFTERNOON HEATING AND INSTABILITY SOMEWHAT. SLOW STORM MOTION WILL
PRODUCE LOCALLY HEAVY RAIN AND POTENTIAL RUNOFF PROBLEMS. A
RELATIVELY DRY NEAR- SURFACE LAYER WILL ALSO ASSIST WITH ENHANCED
LOCAL OUTFLOW WINDS.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
300 AM MDT MON AUG 19 2013
BOUNDARY INTERACTION MAY PRODUCE ISOLATED NOCTURNAL CONVECTION
INTO WEDNESDAY MORNING. THE 593 HIGH REBOUNDS WESTWARD BACK TO
NEAR THE FOUR CORNERS. BOTH THE GFS AND NAM ERODE PRECIPITABLE
WATER VALUES SOMEWHAT UNDER THE HIGH. SUBSIDENCE WILL ALSO CAP
LATE DAY CONVECTION A BIT COMPARED TO TUESDAY. STILL ALL MTN
RANGES WILL LIKELY FIRE SOME AFTERNOON STORMS. STORM MOTION
REMAINS SLOW FOR A CONTINUED THREAT OF LOCALLY HEAVY SHOWERS.
MOISTURE WORKING NORTHWARD ALONG THE WESTERN EDGE OF HIGH PRESSURE
CENTERED ACROSS THE CENTRAL PLAINS WILL KEEP CONDITIONS UNSETTLED
AS WE MOVE THROUGH THE WEEK AND INTO THE WEEKEND. HARD TO PIN
POINT ANY INDIVIDUAL WAVE IN THIS PATTERN FOR ENHANCED
POTENTIAL...SO FOR NOW WILL CONTINUE WITH THE BROAD BRUSH APPROACH
OF DAILY CONVECTION...PRIMARILY FOCUSED ON THE AFTERNOON AND
EVENING HOURS. TEMPERATURES WILL BE RUNNING NEAR SEASONAL NORMS
THROUGH THE PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
300 AM MDT MON AUG 19 2013
SCATTERED SHOWERS AND THUNDERSTORMS WILL AGAIN DEVELOP ACROSS
EASTERN UTAH AND WESTERN COLORADO THIS AFTERNOON AND EVENING. THE
STORMS WILL BE MOST NUMEROUS SOUTH AND EAST OF A LINE FROM K4HV TO
KEGE...ESPECIALLY BETWEEN 20Z THIS AFTERNOON AND 03Z THIS EVENING.
OUTSIDE OF THIS WINDOW...STORMS WILL BE MORE ISOLATED IN NATURE.
EXPECT BRIEF HEAVY RAIN...SMALL HAIL AND GUSTY OUTFLOW WINDS TO
40 MPH IN THE VICINITY OF SHOWERS WITH BRIEF MOUNTAIN OBSCURATIONS
POSSIBLE. STORMS DISSIPATE AFTER 03Z THIS EVENING WITH VFR CONDS
PREVAILING AT ALL TERMINAL SITES.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
UPDATE...JAD
SHORT TERM...JDC/JOE
LONG TERM...JOE/JDC
AVIATION...JDC
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1122 AM EDT MON AUG 19 2013
.SYNOPSIS...
A HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH TUESDAY. A
BROAD...WEAK TROUGH OF LOW PRESSURE WILL REMAIN OVER THE
NORTHEASTERN U.S. TUESDAY NIGHT THROUGH WEDNESDAY NIGHT AS HIGH
PRESSURE REMAINS CENTERED TO OUR SOUTH. A COLD FRONT APPROACHES
FROM THE NORTHWEST THURSDAY...THEN CROSSES THE TRI-STATE THURSDAY
NIGHT AND FRIDAY MORNING. HIGH PRESSURE THEN BUILDS IN FROM THE
NORTHWEST FOR THE UPCOMING WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
SOMEWHAT COMPLICATED SCENARIO UNFOLDING THIS AFTERNOON/EVENING AS
AN ANTICYCLONIC UPPER LEVEL JET STREAK MOVES ACROSS THIS
AFTERNOON...FOLLOWED BY A MID LEVEL TROUGH THIS EVENING. THE JET
STREAK IS INDUCING AN INCREASE IN HIGH CLOUDS ATTM...AND MID LEVEL
CLOUDS SHOULD FOLLOW LATE THIS AFTERNOON AS WELL. SCT SHOWERS OVER
CENTRAL/ERN PA MAY SNEAK IN TO FAR WRN SECTIONS...AND THERE
APPEARS TO BE ENOUGH ELEVATED MUCAPE TO LEAVE IN A SLIGHT CHANCE
MENTION OF THUNDER THERE. FARTHER EAST...SHOULD SEE
SPRINKLES/SHOWERS OUT OF THE ADVANCING MID LEVEL CLOUD DECK.
FORCING AND MOISTURE ADVECTION ARE DISJOINTED...WITH THE UPPER
LEVEL JET STREAK OUTRUNNING OTHER LOWER LEVEL FEATURES...BUT HAVE
SEEN THESE JET STREAKS OUTPERFORM MODEL EXPECTATIONS AND THINK
LAST COUPLE OF RUNS OF THE RAP ARE POINTING IN THE RIGHT DIRECTION
TO WARRANT SPATIAL/TEMPORAL EXTENSION OF AT LEAST SLIGHT CHANCE
POP TO THE REST OF THE CWA...MAINLY THIS EVENING.
AS THE MID LEVEL TROUGH EXITS...THE MID AND UPR LVL MOISTURE WILL
FINALLY START TO BE SHUNTED S AND E OF THE CWA. THIS WILL RESULT
IN CLEARING SKIES OVERNIGHT.
&&
.SHORT TERM /TUESDAY/...
MOSTLY SUNNY WITH BUILDING HEIGHTS AND WARMER TEMPS. WITH WEAK
SUBSIDENCE THRU THE COLUMN...WILL CONTINUE DRY FCST.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
DEEP LAYERED RIDGING BUILDS OVER THE AREA TUESDAY NIGHT AND
WEDNESDAY...WITH THE RIDGE AXIS PASSING TO THE EAST WEDNESDAY
AFTERNOON AND NIGHT. DUE TO SUBSIDENCE UNDER THE RIDGE IT SHOULD BE
DRY WITH MINIMAL CLOUD COVER.
LOWS TUESDAY NIGHT SHOULD BE SLIGHTLY ABOVE NORMAL...CONSISTENT WITH
A BLEND OF MAV/MET GUIDANCE. HIGHS WEDNESDAY WILL RUN 5-10 DEGREES
ABOVE NORMAL...WITH THE POSSIBILITY OF LOCATIONS IN NYC AND URBAN NE
NJ REACHING OR JUST GOING ABOVE THE 90 DEGREE MARK. THIS IS
CONSISTENT WITH A BLEND OF MIXING DOWN FROM 850 HPA NEAR THE COAST
AND 825 HPA INLAND...NAM 2-METER TEMPERATURES AND A BLEND OF MAV/MET
GUIDANCE. FOR NOW IT APPEARS THAT HEAT INDICES WEDNESDAY AFTERNOON
WILL NOT BE MUCH MORE THAN THE AIR TEMPERATURE...SO A HEAT ADVISORY
IS NOT ANTICIPATED TO BE REQUIRED.
USED A BLEND OF MEX/MEN/ECE/WPC GUIDANCE FOR LOWS WEDNESDAY NIGHT
WITH VALUES A FEW DEGREES ABOVE NORMAL FORECAST.
SW FLOW ALOFT ON THURSDAY WITH A PASSING SHORTWAVE...THEN A 700-500
HPA TROUGH CROSSES THE AREA THURSDAY NIGHT AND FRIDAY. FOR NOW
LEANED TOWARDS FASTER ECMWF/CMC OVER SLOWER GFS WITH THE TROUGH
(THOUGH CONVERSELY SLOWER ECMWF/CMC FRONTAL TIMING VICE FASTER GFS).
AS A RESULT...LIMIT POPS TO SLIGHT CHANCE THURSDAY OVER WESTERN
ZONES TO REFLECT THE POTENTIAL FOR SHRA/TSTM WITH PASSING SHORTWAVE
AND THE DEVELOPMENT OF A PRE-FRONTAL TROUGH. GO WITH CHANCE POPS
AHEAD OF THE FRONT/MID-UPPER TROUGH THURSDAY NIGHT...AS IT APPEARS
DYNAMICS SHOULD BE SUFFICIENT TO OVERCOME MEAGER CAPE.
HOWEVER...GIVEN MEAGER CAPE...DID RESTRICT CHANCE OF THUNDER
THURSDAY NIGHT TO SLIGHT CHANCE. THE FRONT SHOULD FINISH MOVING
THROUGH PRETTY QUICKLY FRIDAY MORNING...SO ONLY HAVE SLIGHT CHANCE
POPS ACROSS THE NORTHERN TIER IN RESPONSE TO PASSING OF 700-500 HPA
TROUGH AXIS.
NW FLOW ALOFT IN THE WAKE OF THE DEPARTING TROUGH FRIDAY
NIGHT-SUNDAY. FOR NOW BELIEVE GFS IS TOO PROGRESSIVE - AS IT OFTEN
IS IN THE EXTENDED - IN BUILDING IN THE RIDGE AXIS FROM THE
SPRAWLING 500 HPA RIDGE FORECAST TO BE OVER THE MIDDLE PART OF THE
COUNTRY NEXT WEEKEND. SO DO NOT THINK IT WILL GET QUITE AS WARM AS
THE GFS WOULD SUGGEST. NOTING NO SHORTWAVES/MCS CURRENTLY FORECAST
HAVE GONE DRY SATURDAY-SUNDAY - HOWEVER THIS PATTERN IF THE FORECAST
BEARS OUT IS CONDUCIVE TO MCS DIVING DOWN FROM THE GREAT LAKES SO
WILL NEED TO MONITOR.
FOR TEMPERATURES THURSDAY-SUNDAY USED A BLEND OF MEX/MEN/ECE/WPC
GUIDANCE. TEMPERATURES START OUT ABOVE NORMAL AHEAD OF THE
FRONT...BUT RETURN TO NEAR TO SLIGHTLY BELOW NORMAL LEVELS FOR THE
WEEKEND BEHIND THE FRONT.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
VFR FOR THE PERIOD.
W TO SW FLOW THROUGH THIS AFTERNOON WITH WIND GENERALLY BETWEEN 5
AND 10 KT. WINDS BECOME LIGHT AFTER 02/03Z THIS EVENING. SEA BREEZE
DEVELOPMENT EXPECTED TODAY.
SCT-BKN MID AND HIGH LEVEL CLOUDS...SCATTERING OUT LATER TONIGHT.
LOW CONFIDENCE OF LIGHT RAIN SHOWERS MAINLY WEST AND NORTH OF NYC
LATE AFTN...NOT INCLUDING IN TAFS WITH MINIMAL IMPACT ON CIGS/VIS.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: SEA BREEZE BETWEEN 16 AND 18Z...GENERALLY
SSW FLOW AROUND 12 KT. OCCASIONAL GUSTS UP TO 16 KT AFTN.
KLGA FCSTER COMMENTS: LOW CONFIDENCE OF SEA BREEZE. W FLOW WITH
OCCASIONAL GUSTS UP TO 15 KT THIS AFTN.
KEWR FCSTER COMMENTS: W FLOW WITH PSBL GUSTS UP TO 15 KT THIS
AFTN.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH
IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KISP FCSTER COMMENTS: MOD CONFIDENCE ON SEA BREEZE BETWEEN 16 AND
18Z.
OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY...
.TUE-WED...VFR.
.THU...CHC SUB-VFR IN SHOWERS/TSTM.
.FRI...VFR.
&&
.MARINE...
HIGH PRESSURE CENTERED SW OF THE WATERS WILL KEEP WINDS AND SEAS
BELOW SCA LEVELS THROUGH TUE. WINDS/SEAS E OF MORICHES INLET IN
LONGER FETCH WSW FLOW MAY HOWEVER GET CLOSE TO SCA LEVELS THIS
AFTERNOON.
A RELATIVELY RELAXED PRESSURE GRADIENT OVER THE REGION TUESDAY
NIGHT-FRIDAY WILL KEEP WINDS 10 KT AND SEAS TO 3 FT OR LESS OVER THE
COASTAL OCEAN WATERS AND TO 1 FT OR LESS OVER THE REMAINDER OF THE
WATERS AROUND LONG ISLAND.
&&
.HYDROLOGY...
ORGANIZED RAINFALL IS NOT EXPECTED THROUGH TUE. IT SHOULD THEN BE DRY
THOUGH THE MIDDLE OF THE WEEK.
&&
.EQUIPMENT...
THE NOAA ALL HAZARDS WEATHER RADIO TRANSMITTER IN NEW YORK CITY
HAS BEEN DE-ACTIVATED UNTIL FURTHER NOTICE.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JMC/MALOIT
NEAR TERM...JMC
SHORT TERM...JMC
LONG TERM...MALOIT
AVIATION...BC/SEARS
MARINE...JMC/MALOIT
HYDROLOGY...JMC/MALOIT
AREA FORECAST DISCUSSION
NWS ALBANY NY
1037 AM EDT MON AUG 19 2013
.SYNOPSIS...
DRY WEATHER IS EXPECTED TO CONTINUE INTO THE MID WEEK PERIOD WITH
WARMING TEMPERATURES...AS HIGH PRESSURE REMAINS IN PLACE ACROSS OUR
REGION. A COLD FRONT IS EXPECTED TO DROP SOUTHEAST FROM THE UPPER
GREAT LAKES AND SOUTHEAST CANADA BRINGING A CHANCE OF SHOWERS AND
THUNDERSTORMS LATE THURSDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1037 AM EDT...MORNING FOG HAS BURNED OFF ACROSS THE REGION.
WHILE THE ADIRONDACKS ARE NEARLY CLEAR...A BAND OF MID AND HIGH
LEVEL CLOUDS IS STREAMING NORTHEASTWARD ACROSS THE
CATSKILLS...CAPITAL REGION...AND INTO SRN VT AND THE BERKSHIRES.
THESE CLOUDS...ASSOCIATED WITH A SHORTWAVE TROUGH OVER PA AND A
100+ KT JET STREAK OVER THE NORTHEAST...WILL CONTINUE FOR THE NEXT
SEVERAL HOURS. THE TROUGH WILL BEGIN TO SHEAR OUT BY LATER
TODAY...AND THE BEST BAND OF CLOUDS WILL BEGIN TO SHIFT SOUTH AND
EAST OF THE REGION...ALLOWING FOR SOME IMPROVEMENT IN THE SKY
COVER...WITH MOST AREAS PARTLY CLOUDY BY LATER THIS AFTERNOON.
ANY LIGHT SHOWERS WITH THIS SHORTWAVE SHOULD REMAIN SOUTH OF THE
AREA ACROSS PA AND NJ...SO NO POPS ACROSS OUR REGION TODAY. THE
LATEST 12Z LOCAL HIRES WRF AND 3KM HRRR ALL AGREE THAT WE
SHOULDN/T HAVE ANY SHOWERS IN OUR AREA TODAY AS WELL...WITH THE
BEST MOISTURE/FORCING TO THE SOUTH.
WITH CLOUDS EXPECTED TO CLEAR OR THIN OUT...WE STILL APPEAR ON
TRACK FOR MAX TEMPS IN THE UPPER 70S TO LOW 80S ACROSS LOWER
TERRAIN PORTIONS OF THE AREA. THE HILLS AND MTNS WILL SEE MAX
TEMPS RANGING FROM THE UPPER 60S TO THE MID 70S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
TRANQUIL WEATHER IS EXPECTED THROUGH THE PERIOD WITH WARMING
TEMPERATURES AND SLOWLY RISING HUMIDITY LEVELS. OUR REGION WILL BE
UNDER THE INFLUENCE OF SURFACE HIGH PRESSURE...WITH UPPER LEVEL
HEIGHTS GRADUALLY RISING THROUGH THE PERIOD AS WELL. SO DESPITE
STRONG SURFACE HEATING...CONVECTION IS NOT EXPECTED SINCE UPPER
LEVEL TEMPERATURES WILL BE QUITE WARM /AROUND -7C AT 500 MB TUESDAY
INTO WEDNESDAY/.
WITH THE WARMING ALOFT...MAX TEMPS ON TUESDAY ARE EXPECTED TO REACH
THE MID 80S IN MOST VALLEY LOCATIONS WITH UPPER 80S ON WEDNESDAY.
OVERNIGHT LOWS ARE EXPECTED TO BE ABOVE NORMAL AS WELL...ESPECIALLY
TUESDAY NIGHT AND WEDNESDAY NIGHT WHEN THE WARMEST AIR ALOFT WILL BE
OVER THE REGION. LATE NIGHT/EARLY MORNING PATCHY FOG WILL BE
COMMON IN FAVORED AREAS AGAIN...ESPECIALLY TONIGHT AND TUESDAY
NIGHT.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
MAINLY DRY WEATHER IS EXPECTED DURING THE LONG TERM PERIOD EXCEPT
FOR LATE THURSDAY INTO THURSDAY EVENING WHEN SHOWERS AND
THUNDERSTORMS ARE POSSIBLE ESPECIALLY NORTHERN AREAS AHEAD OF A COLD
FRONT DROPPING SOUTHEASTWARD THROUGH THE FA. WHILE THERE IS LIMITED
MOISTURE TO WORK WITH AHEAD OF THE COLD FRONT...SHOWALTER INDICES
ARE SLIGHTLY NEGATIVE AND SB CAPES RISE BRIEFLY TO BTWN 500 AND 1000
J/KG. WL HAV CHANCE POPS ACRS THE SRN ADIRONDACKS AND LAKE GEORGE
REGION AND SLIGHT CHANCE POPS ELSEWHERE LATE THURSDAY. FRIDAY
THROUGH SUNDAY EXPECT MAINLY DRY CONDITIONS...ALTHOUGH WIDELY
SCATTERED SHOWERS ARE POSSIBLE ON FRIDAY WITH THE UPPER TROF AXIS
CROSSING THE FA.
TEMPS ARE EXPECTED TO BE VERY WARM AHEAD OF THE FRONT ON THURSDAY
FOLLOWED BY A GRADUAL COOL DOWN HEADING INTO THE WEEKEND IN THE WAKE
OF THE COLD FRONT. HIGHS ON THURSDAY ARE EXPECTED TO BE IN THE 80S
TO AROUND 90 WITH MID 70S TO MID 80S ON FRIDAY...70S TO AROUND 80 ON
SATURDAY AND MID 70S TO LOWER 80S ON SUNDAY. LOWS WILL BE IN THE MID
50S TO MID 60S THURSDAY NIGHT AND 50S TO AROUND 60 FRIDAY NIGHT AND
SATURDAY NIGHT.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
ANY AREAS OF FOG AND ASSOCIATED IFR CONDITIONS SHOULD LIFT/BECOME
VFR BY 13Z...WITH VFR CONDITIONS THEN PREVAILING THROUGH THE DAY
MONDAY. A RETURN TO IFR CONDITIONS IS HIGHLY LIKELY AGAIN THIS
EVENING AT KGFL AND KPSF WITH MVFR CONDITIONS POSSIBLE LATE
TONIGHT AT KALB AND KPOU.
LIGHT/VARIABLE WINDS WILL BECOME WEST TO SOUTHWEST AT 5-10 KTS BY
THIS AFTERNOON AND THEN LIGHT AND VARIABLE THIS EVENING.
OUTLOOK...
TUESDAY-WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY-THURSDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF
SHRA...TSRA.
FRIDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
&&
.FIRE WEATHER...
NO FIRE WEATHER RELATED ISSUED ARE EXPECTED THROUGH THE PERIOD.
MINIMUM RELATIVE HUMIDITY VALUES WILL RANGE FROM AROUND 40 TO 50
PERCENT THIS AFTERNOON...WITH FULL RECOVERY TO BETWEEN 95 AND 100
PERCENT TONIGHT WITH DEW FORMATION. RH VALUES WILL DROP TO AROUND 35
TO 45 PERCENT TUESDAY AFTERNOON. WINDS WILL BE WESTERLY AT 5 TO 10
MPH TONIGHT...BECOMING LIGHT AND VARIABLE TONIGHT. WINDS ON TUESDAY
WILL ONCE AGAIN BE WESTERLY AROUND 5 TO 10 MPH.
&&
.HYDROLOGY...
DRY WEATHER IS EXPECTED TO CONTINUE THROUGH THE MIDDLE OF THE
WEEK...WITH RIVER LEVELS NEAR NORMAL FOR MID TO LATE AUGUST. THE
NEXT CHANCE OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
ARRIVES LATE THURSDAY ASSOCIATED WITH A COLD FRONT. THE
PRECIPITATION IS NOT EXPECTED TO BE WIDESPREAD AND SHOULD HAVE
MINIMAL IMPACT ON MAIN STEM RIVERS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...JPV
NEAR TERM...FRUGIS
SHORT TERM...JPV
LONG TERM...11
AVIATION...11
FIRE WEATHER...JPV
HYDROLOGY...JPV
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1033 AM EDT MON AUG 19 2013
.SYNOPSIS...
A STATIONARY FRONT OVER THE AREA WILL DISSIPATE AS HIGH PRESSURE
BUILDS WEST ACROSS THE AREA MID TO LATE WEEK. A WEAK TROUGH OF LOW
PRESSURE WILL APPROACH FROM THE NORTHWEST THIS WEEKEND...FOLLOWED BY
HIGH PRESSURE INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATE MONDAY MORNING...ONGOING FORECASTS REMAINED ON TRACK AND
REQUIRED ONLY MINOR ADJUSTMENTS. RAISED POPS BY 10-20 PERCENT
ACROSS SC/INLAND COUNTIES..CERTAINLY NOT A MAJOR CHANGE BUT STILL
SUFFICIENT TO GENERATE LIKELY POPS CLOSE TO THE CONVERGENCE AXIS
ON THE PERIPHERY OF THE WEDGE STILL IN PLACE N/NW OF THE REGION.
SOUTHEAST GEORGIA AND SOUTHERN SOUTH CAROLINA WILL REMAIN IN THE
NW FLANKS OF THE ATLC SUBTROPICAL RIDGE TODAY. THE DEPARTING UPPER
TROUGH FROM THE OHIO VALLEY TO THE MID SOUTH REGION IS PROGGED TO
LIFT OUT TO THE NE INTO NEW ENGLAND BY LATE DAY. THE TAIL OF THE
MID LEVEL VORT WILL INDUCE SOME VERY WEAK HEIGHT FALLS OVER THE
INLAND CAROLINAS TODAY WHILE DEEP MID SUMMER MOISTURE PERSISTS
REGION-WIDE. THE OLD WEDGE FRONT WILL CONTINUE TO DECAY OVER THE
CAROLINAS TODAY.
MODIFIED 12Z SOUNDINGS AND 00Z-06Z MODEL PROGS SUGGEST AN ACTIVE
CONVECTIVE REGIME TODAY FEATURING EXPANDING COVERAGE OF SHOWERS/
THUNDERSTORMS. POPS ARE GRADUATED FROM HIGH CHANCE/LIKELY ACROSS
INLAND COUNTIES OF SC/GA AND SC COUNTIES FROM COLLETON COUNTY EAST
THROUGH COASTAL LOCATIONS TO 30-40 PERCENT ACROSS FROM JASPER
COUNTY S/SW THROUGH AREAS ALONG/SOUTH OF I-16 INCLUDING THE
SAVANNAH VICINITY. BEST COVERAGE WILL OCCUR SOME OF OUR INLAND
AREAS COULD SEE SOME VERY HEAVY DOWNPOURS IN DEEP CONVECTION THIS
AFTERNOON.
THE 12Z HRRR INDICATES A COMPLEX MESOSCALE ENVIRONMENT FEATURING
NUMEROUS BOUNDARIES INCLUDING THE SE BREEZE...THE INLAND TROUGH
AND OUTFLOW BOUNDARIES. THUS...EXPECT SOME REPEATING SHOWERS/
THUNDERSTORMS WITH LOCALLY HEAVY CONVECTIVE RAINS ESPECIALLY N OF
I-16 AND INLAND FROM U.S. 17 WHERE THE SUBTLE MID LEVEL HEIGHT
FALLS OCCUR. WILL CONTINUE TO HIGHLIGHT A RISK FOR LOCALLY HEAVY
DOWNPOURS AND MINOR TEMPORARY FLOODING CONCERNS FOR OUR NW INLAND
ZONES IN OUR HAZARDOUS WEATHER OUTLOOK. THIS IS MAINLY IN RESPECT
TO THE SOGGY SOIL CONDITIONS AND ONGOING RIVER FLOODING PLUS
SWOLLEN TIDAL CREEKS WITH THE FULL MOON CYCLE.
WE RAISED HIGH TEMPS A DEGREE OR SO IN SOME AREAS AS GUIDANCE IS
RUNNING TOO COOL NOW THE WEDGE TO GONE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
TUESDAY THROUGH THURSDAY...A TYPICAL SUMMERTIME PATTERN WILL EVOLVE
OVER THE SOUTHEASTERN UNITED STATES AS ATLANTIC HIGH PRESSURE
EXPANDS OVER THE AREA THROUGH MIDWEEK. AS THIS OCCURS...DEEPEST
MOISTURE WILL SHIFT INLAND AND WILL BE THE MAIN SOURCE OF PRECIP
ACTIVITY EACH AFTERNOON WHILE WEAK H5 SHORTWAVES PASS OVERHEAD.
DESPITE THE INLAND SHIFT OF DEEPEST MOISTURE...LIGHT ONSHORE FLOW
WILL SUPPORT PWATS BETWEEN 1.5 TO 2 INCHES AS WELL AS SCATTERED
SHOWERS AND/OR THUNDERSTORMS OVER SOUTHEAST SOUTH CAROLINA AND
SOUTHEAST GEORGIA. HOWEVER...EXPECT MOST SHOWERS/THUNDERSTORMS TO
GRADUALLY SHIFT INLAND BY EARLY AFTERNOON EACH DAY ALONG OR AHEAD A
SEABREEZE.
OVERALL HIGH TEMPS SHOULD RANGE IN THE UPPER 80S TO AROUND 90 EACH
AFTERNOON. OVERNIGHT LOWS WILL RANGE IN THE LOW 70S INLAND TO
MID/UPPER 70S ALONG THE COAST.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
A TYPICAL SUMMERTIME PATTERN WILL PERSIST THROUGH LATE WEEK AS
ATLANTIC HIGH PRESSURE REMAINS OVER THE SOUTHEAST. CONDITIONS SHOULD
REMAIN SOMEWHAT DRYER THROUGH FRIDAY WITH WEST/SOUTHWEST FLOW ALOFT.
HIGH PRESSURE WILL THEN GRADUALLY RETREAT SOUTH AND EAST INTO THE
WEEKEND AS A WEAK TROUGH OF LOW PRESSURE APPROACHES FROM THE NORTHWEST.
A SLIGHT CHANCE OF SHOWERS AND/OR THUNDERSTORMS WILL BE POSSIBLE
EACH DAY...WITH POSSIBLY INCREASING CHANCES ON SUNDAY BEFORE SFC
HIGH PRESSURE AND DRYER MID LVL AIR SHIFTS OVER THE SOUTHEAST INTO
EARLY NEXT WEEK. OVERALL HIGH TEMPS SHOULD RANGE IN THE UPPER 80S
TO LOWER 90S EACH AFTERNOON...HIGHEST OVER INLAND AREAS IN
SOUTHEAST GEORGIA. OVERNIGHT LOW TEMPS SHOULD RANGE IN THE LOW 70S
INLAND TO LOW/MID 70S ALONG THE COAST.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
SHOWER/TSTM COVERAGE WILL INCREASE TODAY...AND THE POTENTIAL FOR
DIRECT IMPACTS AT TERMINALS WILL INCREASE. HOWEVER...ASIDE FROM
OCCASIONAL SHOWERS WHICH WILL IMPACT KCHS THROUGH EARLY AFTERNOON
PRECISE TIMING OF SHOWERS/TSTMS AND ASSOCIATED IMPACTS WILL BE
INCLUDED WITHIN AMENDMENTS...WITH VCTS OTHERWISE INDICATED UNTIL
AROUND 00Z. OUTSIDE PRECIPITATION...MAINLY VFR CONDITIONS WILL
PREVAIL...WITH ONLY A LOW PROBABILITY FOR FLIGHT RESTRICTIONS LATE
TONIGHT/EARLY TUESDAY.
EXTENDED AVIATION OUTLOOK...VFR CONDITIONS ARE EXPECTED TO PREVAIL
TUESDAY THROUGH SATURDAY AS HIGH PRESSURE PERSISTS OVER THE
SOUTHEAST. BRIEF MVFR CIGS/VSBYS ARE POSSIBLE EACH AFTERNOON WITH
INLAND MOVING SHOWERS AND/OR THUNDERSTORMS.
&&
.MARINE...
ATLC HIGH PRES WILL BE THE MAIN PLAYER FOR THE WATERS. MAINLY A
S TO SE FLOW 10 KT OR LESS THROUGH TONIGHT WITH SEAS 2 TO 3 FT.
HIGHER WINDS/SEAS COULD DEVELOP LOCALLY WITHIN/NEAR LOCALIZED
SHOWERS/TSTMS.
TUESDAY THROUGH FRIDAY...WINDS/SEAS ARE EXPECTED TO REMAIN WELL
BELOW SMALL CRAFT ADVISORY LEVELS THROUGH LATE WEEK WITH HIGH
PRESSURE DOMINATING THE WATERS. IN GENERAL...SOUTH TO SOUTHEAST
WINDS WILL REMAIN AT OR BELOW 10-12 KT...HIGHEST NEAR SEABREEZE
CIRCULATIONS ALONG THE COAST. SEAS WILL REMAIN AT OR BELOW
3 FT...HIGHEST IN OUTER GEORGIA WATERS.
WATERSPOUTS...IT IS LOOKING DECENT THIS MORNING GIVEN INSTABILITY
AND LIGHT CHAOTIC WIND FIELDS. WILL BE WAITING FOR SUNRISE TO SPOT
CU LINES AND LAND BREEZE BOUNDARIES BEFORE ISSUING ANY MARINE WEATHER
STATEMENTS.
RIP CURRENTS...A SLIGHT INCREASE IN SWELLS COULD LEAD TO A MODERATE
RISK OF RIPS BY MID WEEK. LOW RISK AT AREA BEACHES TODAY.
&&
.TIDES/COASTAL FLOODING...
GIVEN THE PERIGEAN SPRING TIDES...ADDITIONAL COASTAL FLOOD
ADVISORIES ARE POSSIBLE THROUGH MID-WEEK WITH THE EVENING HIGH
TIDE CYCLE. THIS EVENINGS HIGH TIDE SHORTLY BEFORE SUNSET COULD
PRODUCE SHALLOW COASTAL FLOODING IN DOWNTOWN CHARLESTON AND FORT
PULASKI ONCE AGAIN.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...SPR
SHORT TERM...DPB
LONG TERM...DPB
AVIATION...SPR
MARINE...DPB/SPR
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
732 AM EDT MON AUG 19 2013
.SYNOPSIS...
A STATIONARY FRONT OVER THE AREA WILL DISSIPATE AS HIGH PRESSURE
BUILDS WEST ACROSS THE AREA MID TO LATE WEEK. A WEAK TROUGH OF LOW
PRESSURE WILL APPROACH FROM THE NORTHWEST THIS WEEKEND...FOLLOWED BY
HIGH PRESSURE INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
SOUTHEAST GEORGIA AND SOUTHERN SOUTH CAROLINA WILL REMAIN IN THE
NW FLANKS OF THE ATLC SUBTROPICAL RIDGE TODAY. THE DEPARTING UPPER
TROUGH FROM THE OHIO VALLEY TO THE MID SOUTH REGION IS PROGGED TO
LIFT OUT TO THE NE INTO NEW ENGLAND BY LATE DAY. THE TAIL OF THE
MID LEVEL VORT WILL INDUCE SOME VERY WEAK HEIGHT FALLS OVER THE
INLAND CAROLINAS TODAY WHILE DEEP MID SUMMER MOISTURE PERSISTS
REGION-WIDE. THE OLD WEDGE FRONT CONTINUES TO DECAY OVER THE
CAROLINAS TODAY.
FORECAST SOUNDINGS AND 00Z MODEL PROGS INDICATE POTENTIAL FOR
SCATTERED CONVECTIVE RAINS TO DEVELOP OVER PORTIONS THE AREA BY
MID MORNING ONCE THE LAND MASS BEGINS TO QUICKLY WARM AND
ESPECIALLY SINCE SATELLITE IMAGERY SHOWS STRONG POTENTIAL FOR
DIFFERENTIAL HEATING WITH I-95 THE DIVIDING LINE. CHANCE POPS ARE
EXPECTED TO SPREAD INLAND THIS AFTERNOON WITH MANY AREAS ALONG AND
W OF U.S. 17 EXPECTED TO SEE SCATTERED SHOWERS AND TSTMS. SOME OF
OUR INLAND AREAS COULD SEE SOME VERY HEAVY DOWNPOURS IN DEEP
CONVECTION THIS AFTERNOON. THE LATEST 3KM RAP MODEL INDICATES A
PRETTY COMPLEX MESOSCALE AND THUS EXPECT SOME LOCALLY HEAVY
CONVECTIVE RAINS WILL DEVELOP N OF I-16 AND INLAND FROM U.S. 17
WHERE THE SUBTLE MID LEVEL HEIGHT FALLS OCCUR. WE WILL HIGHLIGHT A
RISK FOR LOCALLY HEAVY DOWNPOURS AND MINOR TEMPORARY FLOODING
CONCERNS FOR OUR NW INLAND ZONES IN OUR HAZARDOUS WEATHER OUTLOOK.
THIS IS MAINLY IN RESPECT TO THE SOGGY SOIL CONDITIONS AND ONGOING
RIVER FLOODING PLUS SWOLLEN TIDAL CREEKS WITH THE FULL MOON CYCLE.
WE RAISED HIGH TEMPS A DEGREE OR SO IN SOME AREAS AS GUIDANCE IS
RUNNING TOO COOL NOW THE WEDGE TO GONE.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
TUESDAY THROUGH THURSDAY...A TYPICAL SUMMERTIME PATTERN WILL EVOLVE
OVER THE SOUTHEASTERN UNITED STATES AS ATLANTIC HIGH PRESSURE
EXPANDS OVER THE AREA THROUGH MIDWEEK. AS THIS OCCURS...DEEPEST
MOISTURE WILL SHIFT INLAND AND WILL BE THE MAIN SOURCE OF PRECIP
ACTIVITY EACH AFTERNOON WHILE WEAK H5 SHORTWAVES PASS OVERHEAD.
DESPITE THE INLAND SHIFT OF DEEPEST MOISTURE...LIGHT ONSHORE FLOW
WILL SUPPORT PWATS BETWEEN 1.5 TO 2 INCHES AS WELL AS SCATTERED
SHOWERS AND/OR THUNDERSTORMS OVER SOUTHEAST SOUTH CAROLINA AND
SOUTHEAST GEORGIA. HOWEVER...EXPECT MOST SHOWERS/THUNDERSTORMS TO
GRADUALLY SHIFT INLAND BY EARLY AFTERNOON EACH DAY ALONG OR AHEAD A
SEABREEZE.
OVERALL HIGH TEMPS SHOULD RANGE IN THE UPPER 80S TO AROUND 90 EACH
AFTERNOON. OVERNIGHT LOWS WILL RANGE IN THE LOW 70S INLAND TO
MID/UPPER 70S ALONG THE COAST.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
A TYPICAL SUMMERTIME PATTERN WILL PERSIST THROUGH LATE WEEK AS
ATLANTIC HIGH PRESSURE REMAINS OVER THE SOUTHEAST. CONDITIONS SHOULD
REMAIN SOMEWHAT DRYER THROUGH FRIDAY WITH WEST/SOUTHWEST FLOW ALOFT.
HIGH PRESSURE WILL THEN GRADUALLY RETREAT SOUTH AND EAST INTO THE
WEEKEND AS A WEAK TROUGH OF LOW PRESSURE APPROACHES FROM THE NORTHWEST.
A SLIGHT CHANCE OF SHOWERS AND/OR THUNDERSTORMS WILL BE POSSIBLE
EACH DAY...WITH POSSIBLY INCREASING CHANCES ON SUNDAY BEFORE SFC
HIGH PRESSURE AND DRYER MID LVL AIR SHIFTS OVER THE SOUTHEAST INTO
EARLY NEXT WEEK. OVERALL HIGH TEMPS SHOULD RANGE IN THE UPPER 80S
TO LOWER 90S EACH AFTERNOON...HIGHEST OVER INLAND AREAS IN
SOUTHEAST GEORGIA. OVERNIGHT LOW TEMPS SHOULD RANGE IN THE LOW 70S
INLAND TO LOW/MID 70S ALONG THE COAST.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
A MAINLY VFR FORECAST THIS TAF CYCLE AT THE KCHS/KSAV TERMINALS
WITH POTENTIAL FOR BRIEF MVFR CIGS JUST AFTER SUNRISE AS THE LAND
HEATS AND CUMULUS FIELDS DEVELOP. SCATTERED SHOWERS DEVELOPING
THIS MORNING IN THE COASTAL CORRIDOR PER LATEST RADAR AND MODEL
OUTPUT...PUSHING INLAND THIS AFTERNOON. IF DEEPER CONVECTION
DEVELOPS IT COULD SLIDE BACK INTO THE THE TAF CORRIDOR AFTER MID
AFTERNOON AS STEERING FAVORS A SW-NE TRAJECTORY. CONFIDENCE LOW
ON TIMING OF ANY TSTMS AT THE TERMINALS TODAY.
EXTENDED AVIATION OUTLOOK...VFR CONDITIONS ARE EXPECTED TO PREVAIL
TUESDAY THROUGH SATURDAY AS HIGH PRESSURE PERSISTS OVER THE
SOUTHEAST. BRIEF MVFR CIGS/VSBYS ARE POSSIBLE EACH AFTERNOON WITH
INLAND MOVING SHOWERS AND/OR THUNDERSTORMS.
&&
.MARINE...
ATLC HIGH PRES WILL BE THE MAIN PLAYER FOR THE WATERS. MAINLY A
LIGHT SE TO SSE FLOW THROUGH TONIGHT WITH SEAS 2 TO 3 FT.
TUESDAY THROUGH FRIDAY...WINDS/SEAS ARE EXPECTED TO REMAIN WELL
BELOW SMALL CRAFT ADVISORY LEVELS THROUGH LATE WEEK WITH HIGH
PRESSURE DOMINATING THE WATERS. IN GENERAL...SOUTH TO SOUTHEAST
WINDS WILL REMAIN AT OR BELOW 10-12 KT...HIGHEST NEAR SEABREEZE
CIRCULATIONS ALONG THE COAST. SEAS WILL REMAIN AT OR BELOW
3 FT...HIGHEST IN OUTER GEORGIA WATERS.
WATERSPOUTS...IT IS LOOKING DECENT THIS MORNING GIVEN INSTABILITY
AND LIGHT CHAOTIC WIND FIELDS. WILL BE WAITING FOR SUNRISE TO SPOT
CU LINES AND LAND BREEZE BOUNDARIES BEFORE ISSUING ANY MARINE WEATHER
STATEMENTS.
RIP CURRENTS...A SLIGHT INCREASE IN SWELLS COULD LEAD TO A MODERATE
RISK OF RIPS BY MID WEEK. LOW RISK AT AREA BEACHES TODAY.
&&
.TIDES/COASTAL FLOODING...
GIVEN THE PERIGEAN SPRING TIDES...ADDITIONAL COASTAL FLOOD
ADVISORIES ARE POSSIBLE THROUGH MID-WEEK WITH THE EVENING HIGH
TIDE CYCLE. THIS EVENINGS HIGH TIDE SHORTLY BEFORE SUNSET COULD
PRODUCE SHALLOW COASTAL FLOODING IN DOWNTOWN CHARLESTON AND FORT
PULASKI ONCE AGAIN.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...DPB
LONG TERM...DPB
AVIATION...
MARINE...DPB
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1109 AM EDT Mon Aug 19 2013
...Forecast Update...
Issued at 1107 AM EDT Mon Aug 19 2013
Fog continues to mix out across the southern forecast area this
morning. In most locations, the fog has transitioned over to a low
stratus deck which will take some time to mix out more fully. We
expect that to occur around lunch time or early this afternoon. Cu
field has become better defined across southern KY this morning
despite having a bit more capping aloft. A few isolated showers
will be possible mainly along and SE of the BG Parkway. Additional
isolated showers/storms will be possible later this afternoon.
Forcing is fairly weak from a dynamical standpoint, but differential
heating is probably going to be main forcing mechanism this
afternoon. Temperatures are currently in the lower 70s across the
south, with a belt of mid-upper 70s along and just north of the Ohio
River. Obviously the thicker cloud cover to the south will augment
the solar insolation a bit this afternoon which will likely lead to
a N-S temperature gradient. Highs in the 80-85 degree range in
areas from the KY Parkways and northward still look good. Lower 80s
down across the south and southeastern sections are still
attainable, but will probably occur a little later in the afternoon
due to the cloud cover delaying insolation.
Update issued at 530 AM EDT Mon Aug 19 2013
Updated the forecast to remove areas of fog with patchy dense fog
from southeast Indiana and the Bluegrass region of KY. Mid level
clouds and lesser low level moisture than central and southern KY
(where patches of dense fog have been reported) have limited fog
formation over southeast Indiana and the Bluegrass. Downgraded this
area to just patchy fog for the rest of the pre-dawn hours.
Issued an SPS for portions of south and central KY where patchy
dense fog has been reported and where it rained yesterday (which
should be fog prone). Few-sct mid level clouds continue to move
over this area improving fog at times so feel dense fog coverage
will remain patchy.
.SHORT TERM (Now through Tuesday)...
Issued at 330 AM EDT Mon Aug 19 2013
The main forecast concern in the short term will be fog this
morning. A very moist low level atmosphere along with very light or
nearly calm winds have created an ideal environment for fog
formation which we`ve already seen develop in our area. The worst
fog spots remain over southern IL/western KY and over southwest
Ohio. The 5Z RAP model has these fog areas handled well and expect
them to expand into central KY and portions of southeast IN. Low
clouds will also accompany the fog as soundings indicate a shallow
layer of trapped moisture under a weak inversion. With these
thoughts in mind, think that most locations over southern IN and
central KY will see areas of fog this morning. Some locations over
central KY and southeast IN will probably see patches of dense fog
as well assuming the low clouds don`t inhibit fog density too much.
Will highlight the patchy dense fog in the HWO this morning and
monitor closely in case it becomes more widespread and an SPS or
dense fog advisory is need.
For the rest of the day, fog should burn off fairly quickly after
sunrise. With an upper trough passing through the region, can`t
rule out an isld shower over portions of south and east central KY.
However, did scale the area of potential precip back a bit. High
temperatures should reach the low to mid 80s this afternoon.
Tonight a second upper trough will settle into the mid Mississippi
River Valley. Some fog may be possible but not as widespread as
this morning. Will continue inherited patchy fog mainly in river
valleys. Lows tonight will be in the mid 60s.
For Tues, expect a 20% chance of showers/t-storms to expand from
south to north over the area throughout the day as a vort wave on
the eastern side of the upper trough push north through our area.
Any convection would be on the weak side. Tuesday afternoon high
temps should be in the low to mid 80s with southern Indiana being
the hottest due to a longer period of sunshine before clouds/isld
convection move in.
.LONG TERM (Tuesday Night through Sunday)...
Issued at 311 AM EDT Mon Aug 19 2013
The models have finally come into agreement with a mid-level low
that forms over the Ohio Valley at the start of this forecast
period. This cutoff low hangs out in the region through Thursday
night when it undergoes a transformation into an open wave in
response to an approaching shortwave. This shortwave rides around
the periphery of a stout ridge building in over the Plains and looks
to exit the forecast area by early Saturday. The ridge continues to
build in from the west, giving us dry conditions through the end of
the weekend and into early next week.
Tuesday night through Thursday:
For this issuance, have introduced slight chance PoPs for Tuesday
night as the low establishes itself overhead and surface southerly
flow allows for moisture to be pulled in. Chance PoPs continues for
Wednesday as daytime heating assists in convection across the area.
With the loss of daytime heating and in conjunction with general
model consensus, have kept PoPs out overnight Wednesday into early
Thursday. As the low is depicted to begin traversing eastward
Thursday, have only slight chance during the day with the primary
focus for possible convection more toward eastern KY. The models
have the low slowly but surely progressing eastward during this time
frame and am a little skeptical on its speed. How quickly the low
exits will depend on the timing of a weak frontal boundary
attempting to lay out across the southern Great Lakes by Thursday
night.
Thursday night through Friday night:
Have gone with slight chance PoPs strictly across the northern
sections as the alluded to frontal boundary approaches from the
north. The front stalls well to our north and does not currently
appear to be a factor for us beyond Friday. The aforementioned
shortwave swings around the region Friday, hence the slight to
chance PoPs under diurnally-driven conditions. Again, skepticism
sets in for the timing of it all as it seems to really move through
a little too quickly. For now, have kept the area dry Friday night
until a better handle on the progression of everything plays out.
Temperatures will be more difficult to predict Tuesday night through
Friday night as cloudy skies and/or rain will obviously wreck havoc.
What can be said with confidence is that highs will continue to run
slightly below normal and lows will flirt with normal.
Saturday through Sunday:
With that ridge building in, we`ll begin to see real signs of summer
return as temperatures look to rebound back toward normal and partly
to mostly sunny skies prevail.
&&
.AVIATION (12Z TAF Update)...
Issued at 635 AM EDT Mon Aug 19 2013
While VLIFR conditions exist at BWG, vsbys/cigs at SDF/LEX have not
been near as bad as originally thought thanks to a persistent mid
level cloud deck overnight. So for the rest of the day, expect VFR
conditions at all TAF sites after fog burns off at BWG within the
next few hours. Winds will be light out of the ENE throughout the
TAF period. BWG will once again be fog prone tomorrow morning, but
it should not be as dense as this morning`s fog.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........MJ
Short Term.....AMS
Long Term......lg
Aviation.......AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
702 AM EDT Mon Aug 19 2013
...Updated Aviation Discussion...
...Forecast Update...
Issued at 530 AM EDT Mon Aug 19 2013
Updated the forecast to remove areas of fog with patchy dense fog
from southeast Indiana and the Bluegrass region of KY. Mid level
clouds and lesser low level moisture than central and southern KY
(where patches of dense fog have been reported) have limited fog
formation over southeast Indiana and the Bluegrass. Downgraded this
area to just patchy fog for the rest of the pre-dawn hours.
Issued an SPS for portions of south and central KY where patchy
dense fog has been reported and where it rained yesterday (which
should be fog prone). Few-sct mid level clouds continue to move
over this area improving fog at times so feel dense fog coverage
will remain patchy.
.SHORT TERM (Now through Tuesday)...
Issued at 330 AM EDT Mon Aug 19 2013
The main forecast concern in the short term will be fog this
morning. A very moist low level atmosphere along with very light or
nearly calm winds have created an ideal environment for fog
formation which we`ve already seen develop in our area. The worst
fog spots remain over southern IL/western KY and over southwest
Ohio. The 5Z RAP model has these fog areas handled well and expect
them to expand into central KY and portions of southeast IN. Low
clouds will also accompany the fog as soundings indicate a shallow
layer of trapped moisture under a weak inversion. With these
thoughts in mind, think that most locations over southern IN and
central KY will see areas of fog this morning. Some locations over
central KY and southeast IN will probably see patches of dense fog
as well assuming the low clouds don`t inhibit fog density too much.
Will highlight the patchy dense fog in the HWO this morning and
monitor closely in case it becomes more widespread and an SPS or
dense fog advisory is need.
For the rest of the day, fog should burn off fairly quickly after
sunrise. With an upper trough passing through the region, can`t
rule out an isld shower over portions of south and east central KY.
However, did scale the area of potential precip back a bit. High
temperatures should reach the low to mid 80s this afternoon.
Tonight a second upper trough will settle into the mid Mississippi
River Valley. Some fog may be possible but not as widespread as
this morning. Will continue inherited patchy fog mainly in river
valleys. Lows tonight will be in the mid 60s.
For Tues, expect a 20% chance of showers/t-storms to expand from
south to north over the area throughout the day as a vort wave on
the eastern side of the upper trough push north through our area.
Any convection would be on the weak side. Tuesday afternoon high
temps should be in the low to mid 80s with southern Indiana being
the hottest due to a longer period of sunshine before clouds/isld
convection move in.
.LONG TERM (Tuesday Night through Sunday)...
Issued at 311 AM EDT Mon Aug 19 2013
The models have finally come into agreement with a mid-level low
that forms over the Ohio Valley at the start of this forecast
period. This cutoff low hangs out in the region through Thursday
night when it undergoes a transformation into an open wave in
response to an approaching shortwave. This shortwave rides around
the periphery of a stout ridge building in over the Plains and looks
to exit the forecast area by early Saturday. The ridge continues to
build in from the west, giving us dry conditions through the end of
the weekend and into early next week.
Tuesday night through Thursday:
For this issuance, have introduced slight chance PoPs for Tuesday
night as the low establishes itself overhead and surface southerly
flow allows for moisture to be pulled in. Chance PoPs continues for
Wednesday as daytime heating assists in convection across the area.
With the loss of daytime heating and in conjunction with general
model consensus, have kept PoPs out overnight Wednesday into early
Thursday. As the low is depicted to begin traversing eastward
Thursday, have only slight chance during the day with the primary
focus for possible convection more toward eastern KY. The models
have the low slowly but surely progressing eastward during this time
frame and am a little skeptical on its speed. How quickly the low
exits will depend on the timing of a weak frontal boundary
attempting to lay out across the southern Great Lakes by Thursday
night.
Thursday night through Friday night:
Have gone with slight chance PoPs strictly across the northern
sections as the alluded to frontal boundary approaches from the
north. The front stalls well to our north and does not currently
appear to be a factor for us beyond Friday. The aforementioned
shortwave swings around the region Friday, hence the slight to
chance PoPs under diurnally-driven conditions. Again, skepticism
sets in for the timing of it all as it seems to really move through
a little too quickly. For now, have kept the area dry Friday night
until a better handle on the progression of everything plays out.
Temperatures will be more difficult to predict Tuesday night through
Friday night as cloudy skies and/or rain will obviously wreck havoc.
What can be said with confidence is that highs will continue to run
slightly below normal and lows will flirt with normal.
Saturday through Sunday:
With that ridge building in, we`ll begin to see real signs of summer
return as temperatures look to rebound back toward normal and partly
to mostly sunny skies prevail.
&&
.AVIATION (12Z TAF Update)...
Issued at 635 AM EDT Mon Aug 19 2013
While VLIFR conditions exist at BWG, vsbys/cigs at SDF/LEX have not
been near as bad as originally thought thanks to a persistent mid
level cloud deck overnight. So for the rest of the day, expect VFR
conditions at all TAF sites after fog burns off at BWG within the
next few hours. Winds will be light out of the ENE throughout the
TAF period. BWG will once again be fog prone tomorrow morning, but
it should not be as dense as this morning`s fog.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........AMS
Short Term.....AMS
Long Term......lg
Aviation.......AMS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
701 AM EDT MON AUG 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 359 AM EDT MON AUG 19 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A ZONAL FLOW OVER
SRN CANADA TO THE N OF UPR RDG EXTENDING FM THE WRN PLAINS INTO THE
GREAT LKS. THE WX OVER UPR MI IS QUIET EARLY THIS MRNG...WITH
DRY/STABLE AIRMASS DEPICTED ON THE 00Z MPX/GRB RAOBS DOMINATING THE
AREA. THERE ARE 2 SHRTWVS EMBEDDED IN THE ZONAL FLOW THAT ARE OF
CONCERN. THE FIRST OF THESE IS MOVING EWD THRU THE DAKOTAS
AND ARPCHG NW MN...ACCOMPANIED BY SCT SHRA/TS. THE SECOND IS MOVING
THRU NW ONTARIO WITH A CLUSTER OF SHRA/TS NW OF LK NIPIGON...BUT
SOME ISOLD SHRA/TS WITHIN THE COMMA TAIL OF THIS FEATURE EXTEND
FARTHER S INTO THE MN ARROWHEAD UNDER SOME H85-5 QVECTOR CNVGC
ASSOCIATED WITH FAIRLY VIGOROUS H85 THETA E ADVECTION IN ADVANCE OF
AXIS OF HIER H85 DEWPTS UP TO 15C AT ABERDEEN SDAKOTA AND 13C AT
INL. WHILE THE 00Z MPX/GRB RAOBS ARE QUIET DRY/STABLE WITH KINX OF
0/-2 RESPECTIVELY AND PWAT ARND 0.75 INCH /NEAR 75 PCT OF
NORMAL/...THE 00Z INL RAOB IS MORE MOIST AND CONDITIONALLY
UNSTABLE...WITH KINX OF 36 AND PWAT 1.47 INCH /175 PCT OF NORMAL/.
DESPITE THE RATHER IMPRESSIVE MOISTENING...LATEST TRENDS INDICATE
FEW IF ANY LTG STRIKES WITHIN THE CONVECTION.
MAIN FCST CONCERNS IN THE SHORT TERM ARE RELATED TO PCPN CHCS
ASSOCIATED WITH PAIR OF SHRTWVS NOTED ABOVE.
TDAY...SHRTWVS MOVING INTO MN AND THRU ONTARIO ARE PROGGED TO
CONTINUE DRIFTING E THRU THE DAY. AS AXIS OF VIGOROUS H85 THETA E
ADVECTION/H85-5 QVECTOR CNVGC SHIFT E THIS MRNG...EXPECT SOME ISOLD
SHRA TO INVADE THE WRN COUNTIES. BUT MODEL GUIDANCE IN GENERAL SHOWS
THE SHARPER H85-5 QVECTOR CNVGC ASSOCIATED WITH THE ONTARIO SHRTWV
PASSING TO THE N AND MORE VIGOROUS FORCING IN ADVANCE OF THE MN
DISTURBANCE FOCUSING TO THE S BEFORE FADING IN THE AFTN. SO GOING
FCST SHOWING A DIMINISHING TREND IN THE POPS THRU THE MRNG SEEMS ON
TRACK. GIVEN OBSVD LTG STRIKES AND TENDENCY FOR DIMINISHING DYNAMIC
SUPPORT...REMOVED MENTION OF TS THIS MRNG. WHETHER DAYTIME HEATING
/DESTABILIZATION CAN REINVIGORATE/SUSTAIN ANY CONVECTION WL BE THE
CONCERN FOR THE AFTN. IN FACT...THE 00Z REGIONAL GEM AND GFS ARE THE
ONLY MODELS THAT GENERATE ANY PCPN OVER THE CWA THIS AFTN. THE GFS
FCST SDNGS SHOW RATHER UNIMPRESSIVE LAPSE RATES WITH A TENDENCY FOR
A PERSISTENT CAP AND WARMING MID LVL TEMPS IN THE 18Z-24Z TIME FRAME
ASSOCIATED WITH THE FADING DYNAMIC SUPPORT. NAM/GFS MOS POPS ARE
UNDER 10 AT MOST PLACES...BUT OPTED TO RETAIN SCHC POPS TO INCLUDE
TS WITH ARRIVAL OF MOISTER AIR/PWAT UP TO 1.5 INCH AND SFC TEMPS
EXPECTED TO REACH ARND 85 THAT WL LIFT MUCAPE UP TO 800-1000J/KG
AWAY FM THE MODERATING INFLUENCE OF THE LKS.
TNGT...WITH RISING HGTS/DNVA/DEEP QVECTOR DVGC...TNGT WL BE DRY AS
ANY AFTN CONVECTION FIZZLES BEFORE SUNSET UNDER THE MID LVL
WARMING/LOWERING SUN ANGLE. ALTHOUGH SKIES WL TURN MOCLR...STEADY SW
WIND SHOULD ACT TO LIMIT THE DIURNAL TEMP FALL. THE WARMEST MIN
TEMPS ARE MOST LIKELY NEAR LK SUP OVER THE W HALF...WHERE THE PRES
GRADIENT WL BE A BIT TIGHER/H925 WINDS 20-25 KTS AND THIS FLOW WL
DOWNSLOPE.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 359 AM EDT MON AUG 19 2013
STARTING TUE...THE CWA WILL BE BETWEEN A SFC HIGH OVER THE
ATLANTIC/ERN CONUS AND AND SFC TROUGH FROM HUDSON BAY INTO THE NRN
PLAINS STATES. SOME OF THE MODELS ARE HINTING AT SOME PRECIP TUE
AFTERNOON...BUT ANY PRECIP SHOULD BE ISOLATED AT BEST GIVEN THAT
THERE WILL NOT BE MUCH MOISTURE AVAILABLE. BEST CHANCE FOR ISOLATED
SHOWERS AND THUNDERSTORMS WILL BE OVER NCENTRAL UPPER MI WHERE LAKE
BREEZE CONVERGENCE WILL HELP ENCOURAGE CONVECTION ALONG. 850MB TEMPS
AT 18Z TUE WILL BE RIGHT AROUND 17-18C AND WITH MOSTLY SUNNY SKIES
SHOULD BE ABLE TO GET HIGH TEMPS IN THE 80S TO AROUND 90.
MODELS ARE IN BETTER AGREEMENT FOR THAT TROUGH/COLD FRONT TO THE NW
TO DROP ACROSS THE CWA ON WED/WED NIGHT...BUT THERE REMAINS SOME
SUBTLE YET IMPORTANT UNCERTAINTY FOR THE SYSTEM. MAIN QUESTION IS
WITH THE EXACT TIMING OF THE COLD FRONT...WHICH EVEN THOUGH MODELS
AGREE WELL ON...THINK THAT IT WILL NOT BE CERTAIN UNTIL A LATER
TIME. THE TIMING OF FROPA IS IMPORTANT BECAUSE WITH 850MB TEMPS UP
TO 20C...TEMPS MAY BE COLDER THAN WHAT IS IN THE FORECAST /MAINLY
OVER THE W WHERE THE FRONT MAY COME IN EARLIER THAN PREVIOUSLY
INDICATED BY MODELS/. THINK THAT AREAS THAT HAVE NOT BEEN IMPACTED
BY THE FRONT /AND ASSOCIATED PRECIP AND CLOUD COVER/ BY AROUND PEAK
HEATING TIME WILL GET INTO THE LOW 90S /AWAY FROM LAKE MICHIGAN/.
SO...IF THE COLD FRONT COMES IN AS THE MODELS ARE CURRENTLY
INDICATING /INTO WRN UPPER MI BY 18Z WED AND CENTRAL UPPER MI BY 00Z
THU/...PORTIONS OF WRN UPPER MI WOULD SEE HIGH TEMPS POSSIBLY 10
DEGREES COLDER THAN WHAT THE PREVIOUS FORECAST HAD. ON THE FLIP
SIDE...THE FRONT COULD VERY WELL COME IN LATER THAN INDICATED BY
MODELS...MEANING THE PREVIOUS FORECAST MAY BE RIGHT ON. AT THIS
POINT WITH THE UNCERTAINTY...WILL NOT CHANGE TEMPS MUCH FOR WED. THE
OTHER IMPACT WITH FROPA TIMING IS ON CONVECTION...SIGNIFICANT SBCAPE
VALUES OF 1500-2500J/KG SHOULD BE PRESENT IN AIRMASS AHEAD OF COLD
FRONT AROUND PEAK HEATING...SO WHEN THE FRONT MOVES THROUGH WILL
DETERMINE STRENGTH/COVERAGE OF CONVECTION. AT THIS POINT...NOT TOO
EXCITED WITH AREAL EXTENT OF CONVECTION GIVEN THAT MOISTURE WILL BE
SOMEWHAT LIMITED /AT LEAST EARLY ON/. AT THE SAME TIME...THAT DRY
AIR WILL HELP DCAPE VALUES GET UP TO AROUND 1000J/KG AND WITH HIGH
FREEZING LEVEL AROUND 14KFT...MAIN THREAT FROM ANY STRONGER OR
ISOLATED SEVERE STORMS WOULD BE STRONG WINDS.
THURSDAY CERTAINLY LOOKS COOLER AND DRIER AS 850MB TEMPS AT 18Z THU
WILL BE AROUND 13C WITH SFC HIGH PRESSURE MOVING IN FROM THE W. HIGH
TEMPS LOOK TO BE IN THE 70S TO AROUND 80 OVER THE SCENTRAL CWA.
AMPLIFIED UPPER LEVEL RIDGE WILL BE WELL TO THE W OF THE CWA.
MODELS IN MUCH BETTER AGREEMENT FOR FRI WITH HAVING THE SFC HIGH
EXIT TO THE E ON FRI AS THE UPPER RIDGE AXIS MOVES OVERHEAD LATE IN
THE DAY. WITH SLY FLOW NOT KICKING IN AND UPPER RIDGE NOT ARRIVING
UNTIL LATE IN THE DAY OR UNTIL FRI NIGHT...WILL NOT HAVE SUFFICIENT
ADVECTION OF WARMER AIRMASS INTO THE AREA. HIGH TEMPS LOOK SIMILAR
OR A DEGREE OR TWO COOLER THAN THURSDAY...WITH HIGHS PRIMARILY IN
THE 70S /WITH SOME COOLER SPOTS NEAR LAKE SUPERIOR/.
UNCERTAINTY INCREASES CONSIDERABLY FOR SAT AND SUN DUE TO MODEL
DISAGREEMENT AND RUN TO RUN DISCONTINUITY. WILL JUST USE CONSENSUS
OF MODELS FOR THIS PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 701 AM EDT MON AUG 19 2013
A LO PRES TROF CROSSING THE AREA WL BRING SOME ISOLD -SHRA AND
PERHAPS A TS TO THE TAF SITES W-E TODAY. EVEN IF THERE IS A SHRA AT
ONE OF THE AIRPORTS...CONDITIONS ARE LIKELY TO REMAIN VFR GIVEN THE
RELATIVELY DRY NATURE OF THE AIRMASS. OTRW...EXPECT A GUSTY SW WIND
UNDER THE SHARPER PRES GRADIENT IN ADVANCE OF THE APRCHG TROF AND
WITH DAYTIME HEATING/MIXING. LARGE SCALE SUBSIDENCE BEHIND THE TROF
AND LOSS OF DAYTIME HEATING WL ALLOW FOR DRY/VFR CONDITIONS TNGT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 359 AM EDT MON AUG 19 2013
OVERALL...EXPECT WINDS LESS THAN 20 KTS THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. THE ARRIVAL OF MORE HUMID AIR FOR TUE/WED MAY
RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE WATERS.
HOWEVER...FOG WILL BE MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS
OCCUR OVER THE LAKE. ANY FOG WILL DISSIPATE THU FOLLOWING A COLD
FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
647 AM EDT MON AUG 19 2013
.SYNOPSIS...
A WARM FRONT WILL GRADUALLY BRING MORE SEASONABLE TEMPERATURES
OVER THE NEXT FEW DAYS. WEAK UPPER LEVEL DISTURBANCES WILL KEEP
THUNDERSTORMS SCATTERED THROUGH THE MIDDLE OF THE WEEK. THE LATE
WEEK PERIOD WILL TURN EVEN WARMER WITH LOWER RAIN CHANCES.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM...BASED ON CURRENT RADAR TRENDS...INCREASED RAIN
CHANCES TO CATEGORICAL VALUES NW THIS MORNING AND TO LIKELY VALUES
OVER MUCH OF THE REST OF THE AREA LATER TODAY EXPECTING A LITTLE
MORE COVERAGE THAN PREVIOUSLY THOUGHT. SYNOPSIS...TEMPERATURES AND
SKY INFORMATION IN THE PREVIOUS DISCUSSION FROM 3 AM IS STILL VALID.
THE 3 AM DISCUSSION FOLLOWS:
AS OF 3 AM MONDAY...MODEL GUIDANCE EJECTS THE UPPER LOW OVER THE
MISSISSIPPI VALLEY TO THE NORTHEAST TODAY AND TONIGHT. THE MOTION
OF THIS FEATURE WILL ALLOW LIFT ASSOCIATED WITH THE ENTRANCE REGION
OF THE UPPER JET TO AFFECT THE AREA TODAY...PARTICULARLY NW
SECTIONS. IN ADDITION MODEL GUIDANCE SHOWS WEAK ISENTROPIC LIFT
OVER THE AREA TODAY AND THE OLD FRONTAL BOUNDARY REMAINS IN THE
AREA AS WELL. FORECAST WILL HAVE HIGH CHANCE TO LIKELY POPS TODAY
WITH HIGHEST NUMBERS NW...TAPERING BACK TO SLIGHT CHANCE TONIGHT.
AFTERNOON MAXIMUM TEMPERATURES UNDER A PARTLY TO MOSTLY CLOUDY SKY
SHOULD BE LIMITED TO THE MIDDLE 80S. MINS TONIGHT SHOULD FALL TO
THE LOWER 70S...PERHAPS UPPER 60S NW.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 AM MONDAY...MODELS HAVE SLOWED IN SHOWING THE INLAND
PROGRESSION OF THE MID LEVEL WEST ATLANTIC RIDGE. NOW TUESDAY IS
DEPICTED AS ONE LAST DAY WHERE MOISTURE REMAINS DEEP AND A FEW WEAK
SHORTWAVES EMBEDDED IN THE 10KT 500MB FLOW PROVIDE SOME SYNOPTIC
SCALE ASCENT. TEMPERATURES WILL BE CLOSE CLIMO BUT SLIGHTLY HIGHER
THAN NORMAL POPS APPEAR TO BE WARRANTED. WEDNESDAY THE WEST ATLANTIC
RIDGE GAINS IN AMPLITUDE BACKING LOCAL FLOW ALMOST TO SOUTHERLY.
MEANWHILE THE CHANNEL OF DEEPEST MOISTURE GETS SHUNTED JUST TO OUR
WEST. ISO TO WIDELY SCATTERED CONVECTION TILL POSSIBLE ALONG
MESOSCALE BOUNDARIES AND TEMPS MAY RISE A FEW DEG ABOVE TUESDAY
COUNTERPARTS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 3 AM MONDAY...FOR THE FIRST FEW DAYS OF THE LONG TERM THE WEST
ATLANTIC UPPER RIDGE BUILDS IN FAVOR OF THE BUILDING RIDGE OVER THE
WESTERN U.S. A WEAK SHEAR AXIS CROSSES THE REGION THURSDAY NIGHT
INTO FRIDAY. WEAK ASCENT ASSOCIATED WITH THIS FEATURES SHOULD BRING
SOME HIGHER RAIN CHANCES THAN WEDNESDAY BUT STILL PROBABLY NOT MUCH
HIGHER THAN CLIMO. THE REMAINDER OF THE PERIOD KEEPS A STRONG UPPER
RIDGE ACROSS THE MIDDLE OF THE NATION WITH TROUGHINESS ALONG BOTH
COASTLINES. BARRING THE RELATIVELY NEW IDEA OF THE GFS OF A BACKDOOR
COLD FRONT OVER THE WEEKEND THIS WILL MEAN SLIGHTLY ABOVE CLIMO
TEMPS AND SLIGHTLY LOWER THAN NORMAL THUNDERSTORM COVERAGE.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 06Z...SURFACE DEWPOINTS IN THE LOW TO MID 70S WITH CALM/LIGHT
WINDS SUGGEST THE LOW-LEVEL CONDITIONS ARE PRIMED FOR FOG/STRATUS
OVERNIGHT. MVFR CIGS/VSBYS ARE EXPECTED AT THE COASTAL TERMS...WITH
PERHAPS SOME BRIEF IFR VSBYS AT FOG-PRONE KCRE. KFLO/KLBT HAVE THE
BEST CHANCES FOR IFR...AS THE LATEST GUIDANCE FAVORS STRATUS
DEVELOPING AROUND DAYBREAK AT THE INLAND SITES. THE LATEST HRRR RUNS
SHOW SOME SHOWERS MOVING ONSHORE IN THE EARLY MORNING HOURS...SO
HAVE MENTIONED PCPN FOR THE COASTAL SITES AS WELL. CURRENT SHOWER
ACTIVITY INLAND HAS A CHANCE TO AFFECT THE INLAND TERMINALS THROUGH
ABOUT 09Z...PARTICULARLY FLO. MORE WIDELY SCATTERED SHOWERS ARE
EXPECTED WITH DAYTIME HEATING AS A COASTAL TROUGH WILL BE POSITIONED
OVER THE CAROLINAS. CIGS MAY BOUNCE AROUND BETWEEN VFR AND MVFR
DURING THE DAY...WITH MVFR MORE LIKELY DURING PERIODS OF SHRA.
SLIGHTLY HIGHER POPS INLAND ARE REFLECTED IN THE TAFS. CALM TO LIGHT
WINDS WILL BECOME S-SE AOB 10 KTS AT KMYR...KCRE AND KILM IN THE
AFTN HOURS.
EXTENDED OUTLOOK...EARLY MORNING FOG/STRATUS POSSIBLE TUESDAY AND
WEDNESDAY. ISOLATED TO SCATTERED AFTN SHOWERS/T-STORMS EXPECTED
THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM MONDAY...OUTSIDE OF LIGHT N TO NW WINDS EARLY TODAY DUE
TO A LAND BREEZE...EXPECT SE TO S FLOW AT 10 KT OR LESS THROUGH THE
PERIOD. SEAS ARE EXPECTED TO RUN 2 TO 3 FT.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 AM MONDAY...TWIN CENTERED HIGH PRESSURE ON TUESDAY...ONE OFF
THE COAST AND THE OTHER OVER THE MOUNTAINS. RESULTING FLOW ACROSS
THE WATERS WILL BE QUITE LIGHT AND SOMEWHAT VARIABLE ALTHOUGH A
PREDOMINANTLY SOUTHERLY COMPONENT WILL BE PRESENT. THE OVER LAND
HIGH WILL BE SHRINKING ON WEDNESDAY WITH LITTLE EFFECT ON LOCAL
WINDS AND THE CONTINUED DIMINUTIVE SEAS.
LONG TERM /THURSDAY THROUGH FRIDAY/...
AS OF 3 AM MONDAY...HIGH PRESSURE OVER THE LANDMASS/EASTERN U.S.
DURING THE SHORT TERM FINALLY WASHES OUT ENOUGH TO BRING A MORE
SEASONABLE SW FLOW ON THURSDAY AROUND THE WEST ATLANTIC HIGH. THIS
FLOW CONTINUES INTO FRIDAY BUT MAY BE EQUALLY BORNE OF PIEDMONT
TROUGHINESS AS THE WEAKENING WEST ATLANTIC RIDGE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MBB
NEAR TERM...RAN
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...BJR/31
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
641 AM CDT MON AUG 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 327 AM CDT MON AUG 19 2013
THE MAIN FOCUS FOR TODAY IS ON A MID LEVEL TROUGH THAT WILL COME
THROUGH AND WHETHER IT WILL HAVE ENOUGH LIFT TO OVERCOME THE DRY
LOW LEVEL AIR AND PRODUCE SOME RAIN SHOWERS.
THIS MID LEVEL TROUGH IS CURRENTLY ANALYZED VIA WATER VAPOR IR AND
19.06Z RAP 500MB ANALYSIS FROM SOUTHWESTERN ONTARIO THROUGH
MINNESOTA AND EASTERN NEBRASKA. SOME VERY HIGH BASED RADAR RETURNS
HAVE BEEN SHOWING UP ACROSS EASTERN SOUTH DAKOTA AND WESTERN
MINNESOTA THOUGH THERE HAVE NOT BEEN MANY SIGHTS REPORTING THAT
THE RAIN IS REACHING THE GROUND. THIS IS ALSO IN A BELT OF HIGHER
LOW LEVEL MOISTURE TRANSPORT THAT IS TRAPPED UNDER A 700MB
INVERSION...BUT IS HELPING TO RAISE SURFACE DEW POINTS. THIS IN
TURN HAS CREATED A MORE UNSTABLE AIR MASS FROM THE DAKOTAS UP INTO
NORTHERN MINNESOTA. THE 19.07Z RAP KEEPS MUCH OF THIS MOISTURE
TRANSPORT AND HIGHER INSTABILITY OUT TO THE WEST TODAY...SO THIS
TROUGH WILL BE ENTERING AN ENVIRONMENT THAT IS LESS FAVORABLE TO
SEE THE SHOWERS CONTINUE. CONSIDERED PUTTING IN A MENTION OF
SPRINKLES TODAY IN FOR SOUTHEAST MINNESOTA AND WESTERN TO NORTH
CENTRAL WISCONSIN...BUT HELD OFF FOR THE TIME BEING SINCE
REFLECTIVITIES OUT WEST APPEAR TO BE ON A WEAKENING TREND.
MID TO HIGH LEVEL CLOUD COVER WILL BE FAIRLY WIDESPREAD FOR A
PORTION OF THE DAY WHICH WILL KEEP TEMPERATURES DOWN A LITTLE BIT.
THE 19.00Z NAM/GFS SHOW SOME WARMER 850/925MB AIR MOVING IN THIS
AFTERNOON AS SOME OF THIS CLOUD COVER EXITS. EXPECT THAT WE WILL
WARM UP PRETTY QUICKLY AS THIS OCCURS...BUT PERHAPS NOT AS HIGH AS
PREVIOUSLY ADVERTISED.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 327 AM CDT MON AUG 19 2013
CONDITIONS WILL CONTINUE TO WARM INTO MID WEEK AHEAD OF A COLD
FRONT/TROUGH THAT WILL PROPAGATE INTO THE REGION ON WEDNESDAY.
WEDNESDAY IS EXPECTED TO BE THE WARMEST DAY OF THE WEEK WITH LOW
LEVEL WARM AIR ADVECTION BUMPING 925MB TEMPERATURES UP TO AROUND
26C AND 850MB TEMPERATURES TO 20C. THIS WARM LAYER SHOULD ALSO
HELP TO KEEP THE WARM SECTOR CAPPED OFF UNTIL THE COLD FRONT DROPS
DOWN LATE WEDNESDAY AFTERNOON AND EVENING. THE AIR MASS WILL
BECOME UNSTABLE WITH MODIFIED 19.00Z NAM/GFS SOUNDINGS...MODIFIED
FOR LOWER DEW POINTS IN THE MID/UPPER 60S...SHOWING BETWEEN
1500-2500 J/KG OF 0-3KM MUCAPE ALONG A NARROW CORRIDOR JUST AHEAD
OF THE FRONT. WIND SHEAR LOOKS MARGINAL WITH THE BETTER DEEP SHEAR
IN CENTRAL MINNESOTA/NORTHERN WISCONSIN WHERE 500MB WINDS WILL BE
AROUND 40KTS DUE TO THE MID LEVEL SHORT WAVE TROUGH DROPPING INTO
THE NORTHERN GREAT LAKES. FURTHER SOUTHWEST ALONG THE FRONT CLOSER
TO SOUTHERN MINNESOTA AND NORTHERN IOWA...19.00Z NAM/GFS
SOUNDINGS/HODOGRAPHS DO SHOW SOME DIRECTIONAL/SPEED SHEAR IN THE
LOWEST 2KM WHICH WOULD BE MORE FAVORABLE FOR STRONGER WINDS. BASED
ON THE INSTABILITY AND SHEAR...IT APPEARS THAT LARGE HAIL AND
DAMAGING WINDS STILL APPEAR TO BE THE MAIN THREATS IN THE LATE
AFTERNOON INTO THE EVENING...PARTICULARLY ACROSS SOUTHEAST
MINNESOTA...WESTERN WISCONSIN AND NORTHEAST IOWA.
THE ISSUE THEN CONTINUES TO BE WITH HOW FAR SOUTH WILL THE COLD
FRONT MAKE IT AND THEN HOW FAST DOES IT GET PUSHED BACK TO THE
NORTH AS A WARM FRONT BY THE END OF THE WEEK. THE ECMWF HAS
TRENDED TOWARD WHAT THE GFS/GEM HAVE BEEN ADVERTISING THE PAST FEW
DAYS WITH HAVING THE FRONT DROP SOUTH INTO IOWA/NORTHERN ILLINOIS
BY THURSDAY MORNING...BUT THE 19.00Z ECMWF STILL REMAINS THE
FURTHEST NORTH WITH WHERE IT STALLS OUT. THERE ALSO IS BETTER
CONTINUITY WITH THE NEXT TROUGH TRACKING ACROSS THE NORTHERN
PLAINS ON FRIDAY INTO SATURDAY WHICH IS WHEN THE FRONT COMES BACK
NORTH AS A WARM FRONT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 641 AM CDT MON AUG 19 2013
MVFR CONDITIONS ARE EXPECTED AT KLSE THROUGH 14Z THIS
MORNING. OTHERWISE...VFR CONDITIONS ARE EXPECTED AT THE TAF SITES
THROUGH THE FORECAST PERIOD. PATCHY FOG HAS DEVELOPED ALONG THE
MISSISSIPPI RIVER THIS MORNING. PLAN ON VISIBILITIES BEING REDUCED
TO AROUND 4SM AT KLSE BEFORE THE FOG FINALLY DISSIPATES AROUND
14Z. A WEAK UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY TODAY BRINGING SCATTERED TO BROKEN VFR
CEILINGS. ALSO...SOUTHWEST WINDS WILL INCREASES TO AROUND 10KTS
WITH GUSTS AROUND 20 KTS POSSIBLE THIS AFTERNOON. THE WINDS WILL
SUBSIDE INTO THE 5 TO 7 KT RANGE TONIGHT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS SAN JOAQUIN VALLEY - HANFORD CA
309 PM PDT MON AUG 19 2013
.SYNOPSIS...
A LOW PRESSURE CENTER OFF THE CENTRAL COAST WILL BRING A CHANCE OF
MAINLY AFTERNOON AND EVENING THUNDERSTORMS OVER THE SIERRA NEVADA
THROUGH WEDNESDAY. THERE WILL ALSO BE A SLIGHT CHANCE OF
THUNDERSHOWERS FOR THE SAN JOAQUIN VALLEY THROUGH TUESDAY MORNING.
THE LOW WILL LIFT NORTHEAST OUT OF THE REGION BY THURSDAY AND BRING
A RETURN OF DRIER WEATHER FOR THE END OF THE WEEK.
&&
.DISCUSSION...
UPPER LOW OFF THE COAST IN CONJUNCTION WITH LARGE SCALE UPPER
RIDGE OVER THE FOUR CORNERS IS PROVIDING A SQUEEZE PLAY TO STREAM
MID LEVEL SUB TROPICAL MOISTURE INTO THE CENTRAL CA INTERIOR.
T-STORMS ARE ONCE AGAIN FIRING UP OVER THE SIERRA AND ALONG THE
TEHACHAPI RANGE ATTM. UPSLOPE CONDITIONS IN ASSOCIATION WITH
MODERATE MUCAPES FROM THE VEGAS SOUNDING OF OVER 2000 J/KG ARE
PROVIDING ENOUGH LIFT TO GET IT GOING AGAIN TODAY. BLENDED PWAT
VALUES OF 1.0-1.5 ARE OVER THE REGION WILL PROVIDE ENOUGH MOISTURE
TO SUPPORT THUNDERSTORMS. ACTIVE PATTERN WILL CONTINUE INTO THE
OVERNIGHT HOURS AS UPPER LOW REMAINS STATIONARY OFF THE COAST AND
MOISTURE FEED CONTINUES.
19Z RUN OF THE HRRR IS PAINTING MOST OF THE CWA WITH QPF FOR THIS
EVENING. EVEN SPREADS QPF INTO THE VALLEY AND OVER TO THE WEST
SIDE OF THE SJV. SOME FLASH FLOODING IS POSSIBLE WITH THE STORMS
IN THE MOUNTAINS AS MOVEMENT IS ONLY AROUND 10 MPH. ADDITIONAL
FIRE STARTS ARE ALSO POSSIBLE WITH NUMEROUS LIGHTNING STROKES
ASSOCIATED THE STORMS.
THE UPPER LOW BEGINS TO OPEN UP AND LIFT NE. BOTH THE MEAN
ENSEMBLE GFS AND THE 12Z OPERATIONAL ECM ARE IN DECENT AGREEMENT
WITH LIFTING THE FEATURE NE BY WED AND SW FLOW ALOFT SETTING UP
WITH DRIER CONDITIONS. EPAC TROUGH WILL DIG SOUTH AND FEED ANOTHER
ROUND OF SUB TROPICAL MOISTURE INTO THE REGION. HAVE INTRODUCED
POPS FOR SUNDAY AND MONDAY OVER THE SIERRA AND OVER THE
TEHACHAPIS.
&&
.AVIATION...
SCATTERED SHOWERS AND THUNDERSTORMS WITH LOCAL MVFR/IFR CONDITIONS
EXPECTED TODAY...MAINLY OVER THE MOUNTAINS AND DESERT. OTHERWISE...
VFR CONDITIONS WILL PREVAIL THROUGHOUT THE CENTRAL CALIFORNIA
INTERIOR DURING THE NEXT 24 HOURS.
&&
.AIR QUALITY ISSUES...
ON MONDAY AUGUST 19 2013... UNHEALTHY FOR SENSITIVE GROUPS IN
SEQUOIA NATIONAL PARK AND FOREST.
FURTHER INFORMATION IS AVAILABLE AT VALLEYAIR.ORG
&&
.CERTAINTY...
THE LEVEL OF CERTAINTY FOR DAYS 1 AND 2 IS MEDIUM.
THE LEVEL OF CERTAINTY FOR DAYS 3 THROUGH 7 IS HIGH.
THIS INFORMATION IS PROVIDED AS PART OF A TRIAL PROJECT CONDUCTED
BY THE NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD.
CERTAINTY LEVELS INCLUDE LOW...MEDIUM...AND HIGH. PLEASE VISIT
WWW.WEATHER.GOV/HNX/CERTAINTY.PHP /ALL LOWER CASE/ FOR ADDITIONAL
INFORMATION AND/OR TO PROVIDE FEEDBACK.
&&
.CLIMATE...
RECORDS
SITE DATE HI_MAX:YEAR LO_MAX:YEAR HI_MIN:YEAR LO_MIN:YEAR
KFAT 08-19 108:1892 67:1976 74:2012 54:1916
KFAT 08-20 108:1919 76:1959 75:1986 54:1974
KFAT 08-21 108:1919 80:1968 76:1913 51:1959
KBFL 08-19 109:1950 78:1959 79:1961 52:1913
KBFL 08-20 112:1950 77:1959 79:1950 52:1912
KBFL 08-21 110:1919 80:1968 77:1982 51:1918
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
PUBLIC...JDB
AVN/FW...MV
SYNOPSIS...ANDERSEN
WEATHER.GOV/HANFORD
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
1030 AM PDT MON AUG 19 2013
.SYNOPSIS...
CHANCE OF THUNDERSTORMS INTO THURSDAY AS A LOW PRESSURE SYSTEM
ALONG THE CENTRAL COAST GRADUALLY MOVES THROUGH NORTHERN
CALIFORNIA. HOT WEATHER WILL CONTINUE TODAY FOLLOWED BY A RETURN
TO NEAR SEASONAL TEMPERATURES BY MID-WEEK.
&&
.DISCUSSION...
UPPER LEVEL LOW PRESSURE OFF THE COAST HAS DROPPED FURTHER TO SOUTH
AND WEST. THIS SYSTEM IS PUMPING SIGNIFICANT MOISTURE INTO THE
AREA. THE OAKLAND MORNING SOUNDING SHOWS THIS WITH PRECIPITABLE
WATER AT OAKLAND AROUND 200 PERCENT OF NORMAL. SATELLITE SHOWS CLOUDS
WRAPPING AROUND AND STREAMING WESTWARD THROUGH THE VALLEY,
CURRENTLY EXTENDING NORTH AND SOUTH BETWEEN RED BLUFF AND GALT.
THIS IS BRINGING OVERCAST SKIES TO THAT AREA. RADAR ALSO SHOWS
SOME EMBEDDED RETURNS WITH PERHAPS SOME SPRINKLES IN THE VALLEY OR
A FEW LIGHT RAIN SHOWERS THE MOUNTAINS AND FOOTHILLS. MESOSCALE
MODELS SHOW MORE SIGNIFICANT PRECIPITATION SPREADING INTO THE
MOUNTAINS BY THIS AFTERNOON. THE WRF EXTENDS SOME SHOWERS AND
THUNDERSTORMS INTO THE NORTHERN AND PORTIONS OF THE CENTRAL
SACRAMENTO VALLEY BY LATE AFTERNOON AND AM FORECASTING SCATTERED
STORMS FOR THAT AREA. THE HRRR KEEPS MOST OF THE CONVECTION OVER
HIGHER TERRAIN...THOUGH. THIS MAY BE DUE TO RELATIVELY DRY AIR
NEAR THE SURFACE, WHICH IS EVIDENT IN AIRCRAFT SOUNDINGS THIS
MORNING. THE SOUTHERN VALLEY LOOKS LIKE IT HAS LESS CHANCE OF
ACTIVITY ALTHOUGH WILL KEEP SOME ISOLATED SHOWERS AND
THUNDERSTORMS THERE FOR THIS EVENING. OVERALL, THE STRONGEST
THUNDERSTORM ACTIVITY IS EXPECTED TO BE OVER THE SIERRA AND
MOUNTAINS OF WESTERN PLUMAS COUNTY AND DOWN INTO THE FOOTHILLS
WITH LOCALLY HEAVY RAIN AND SIGNIFICANT AMOUNTS OF CLOUD TO GROUND
LIGHTNING POSSIBLE. RED FLAG WARNING CONTINUES FOR THE THREAT OF
WILDFIRE STARTS DUE TO LIGHTNING. LIGHTNING STRIKES
YESTERDAY/OVERNIGHT WERE REPORTED TO HAVE STARTED SOME FIRES.
A VERY WARM START TO THE DAY TODAY WITH SOME LOCATIONS OVER THE
NORTHERN SACRAMENTO VALLEY AND FOOTHILLS ONLY DROPPING TO THE
UPPER 70S TO LOWER 80S. A LACK OF A DELTA BREEZE ALSO CONTRIBUTED
TO THIS. HIGH TEMPERATURES TODAY COULD BE TRICKY AS CLOUDS MAY ACT
TO LIMIT SOLAR HEATING. MAY NEED TO MAKE SOME ADJUSTMENTS TO
AFTERNOON HIGHS.
MORE WIDESPREAD CONVECTION IS EXPECTED ON TUESDAY AS THE LOW
BEGINS TO SLOWLY SHIFT NORTHWARD. EK
&&
.EXTENDED DISCUSSION (FRIDAY THROUGH MONDAY)
SOME CHANGES TO THE FORECAST ON THURSDAY WITH INCREASED CHANCES OF
SHOWERS AND THUNDERSTORMS OVER THE NORTHERN MOUNTAINS AND
NORTHERN SACRAMENTO VALLEY THROUGH THE DAY AND INTO THE EARLY
EVENING. MODELS HAVE SLOWED DOWN THE DEPARTURE OF THE UPPER LOW
WITH IT LINGERING OVER NORTHERN CALIFORNIA THROUGH THE DAY
THURSDAY. THERE IS FAIRLY GOOD AGREEMENT NOW BETWEEN THE ECMWF,
THE GFS AND THE GEM WITH THE CORE OF THE LOW CENTERED AROUND
SACRAMENTO BY LATE MORNING. CONVECTIVE ACTIVITY SHOULD BE LIMITED
TO THE NORTHERN PORTION OF THE FORECAST AREA WITH DRIER MORE
STABLE MOVING IN TO THE SOUTH. HIGH TEMPERATURES SHOULD BE AROUND
NORMAL LEVELS BUT WILL DEPEND ON THE DEGREE OF CLEARING DURING THE
DAY. THE LOW WILL SHOULD HAVE EXITED THE AREA BY LATE FRIDAY
EVENING.
THIS TIMING SUGGESTS THE LOW SHOULD WEAKEN AND EXIT THE REGION
OVERNIGHT WITH DRY WEATHER FOR FRIDAY AND SATURDAY WITH STABLE
SOUTHWEST FLOW. TEMPERATURES SHOULD BE AT TO A LITTLE BELOW
NORMAL. EK
&&
.AVIATION...
SMOKE IN VICINITY OF WILDFIRES WILL CONTINUE TO CAUSE LOCAL
IFR/MVFR VISIBILITIES SOUTH OF KBLU TO KAUN AND EAST OF KOVE.
OTHERWISE, VFR CONDITIONS WILL PREVAIL ACROSS THE REGION. MAIN
AVIATION CONCERN TODAY WILL BE ISOLATED TO SCATTERED
SHOWER/THUNDERSTORM DEVELOPMENT BOTH IN THE MOUNTAINS AND OVER THE
VALLEY WITH LOCAL MVFR/IFR CONDITIONS ASSOCIATED WITH STORMS.
MOUNTAINS ARE MORE LIKELY TO HAVE SCATTERED COVERAGE OF -SHRA/-TSRA STARTING
AFTER 18Z. VALLEY LOCATIONS WILL INITIALLY JUST HAVE ISOLATED
-SHRA/-TSRA DURING MORNING AND AFTERNOON BUT THEN BECOME SCATTERED
AFTER 00Z, ESPECIALLY NORTH OF I-80. LIGHT WINDS FOR ALL TAF SITES
TODAY AROUND 10-12 KTS OR LESS, HOWEVER, ERRATIC GUSTY WINDS
POSSIBLE IF THUNDERSTORMS DEVELOP. JBB
&&
.STO WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 5 AM PDT THURSDAY NORTHEAST
FOOTHILLS/SACRAMENTO VALLEY...WESTERN PLUMAS COUNTY/LASSEN PARK.
RED FLAG WARNING UNTIL 11 PM PDT WEDNESDAY CLEAR LAKE/SOUTHERN
LAKE COUNTY...MOTHERLODE...MOUNTAINS SOUTHWESTERN SHASTA COUNTY
TO NORTHERN LAKE COUNTY...WEST SLOPE NORTHERN SIERRA NEVADA.
RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 11 PM PDT WEDNESDAY
CENTRAL SACRAMENTO VALLEY.
RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 5 AM PDT THURSDAY
BURNEY BASIN / EASTERN SHASTA COUNTY...NORTHERN SACRAMENTO
VALLEY...SHASTA LAKE AREA / NORTHERN SHASTA COUNTY.
&&
$$
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
950 AM PDT MON AUG 19 2013
.SYNOPSIS...
UPPER LEVEL LOW PRESSURE WEST OF POINT CONCEPTION WILL DRAW A
LIMITED AMOUNT OF MID LEVEL MONSOONAL MOISTURE INTO SOUTHERN
CALIFORNIA WITH WIDELY SCATTERED THUNDERSTORMS FOR THE MOUNTAINS AND
DESERTS OF SAN BERNARDINO AND RIVERSIDE COUNTIES THROUGH THIS
EVENING. THE THUNDERSTORMS WILL PRODUCE LIGHTNING STRIKES...LOCALLY
STRONG GUSTY WINDS...AND BRIEF HEAVY RAINFALL. AS THE TROUGH OF LOW
PRESSURE WEAKENS AND MOVES INLAND THROUGH NORTHERN AND CENTRAL
CALIFORNIA...DRIER SOUTHWEST FLOW ALOFT AND STRONGER ONSHORE FLOW
WILL FOLLOW FOR TUESDAY AND WEDNESDAY...WEAKENING LATE IN THE WEEK.
A GREATER INFLUX OF MONSOONAL MOISTURE IS POSSIBLE FOR NEXT WEEKEND
THROUGH EARLY NEXT WEEK.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
REMAINDER OF TODAY THROUGH THIS EVENING...
MOST OF SAN BERNARDINO COUNTY HAD NATURES ALARM CLOCK GO OFF THIS
MORNING WITH THUNDERSTORMS BEGINNING SHORTLY BEFORE 0400 PDT AND
CONTINUING UP UNTIL 0830 PDT. THE 19/12Z ANALYSES SHOWED THE LOW IS
VERTICALLY STACKED AND CLOSED FROM 925 MB UP TO 200 MB. THIS WOULD
ARGUE FOR A BAROTROPIC MODEL SOLUTION AND THE ONLY AVAILABLE MODELS
AT THE FIELD OFFICE LEVEL ARE ALL BAROCLINIC. THOUGH THESE ARE SLOW
IN MOVING THE LOW OUT TO THE NORTHEAST...2 KTS/LESS THAN 3
MPH...THEY MAY STILL BE TOO FAST. PLAN TO USE HRRR MODEL AS MODEL OF
CHOICE FOR FIRST/SECOND PERIODS. ALREADY DID SOME QUICK
MODIFICATIONS TO THE GRIDS AND ISSUED UPDATES TO THE ZONE FORECAST
PRODUCTS.
REMAINDER OF TONIGHT INTO WEDNESDAY...
NO CHANGES ANTICIPATED TO CURRENT GRIDS/FORECAST AS THEY AGREE WITH
LATEST GUIDANCE...ASSUMING THESE BAROCLINIC MODELS ARE NOT TOO FAST
ON DRYING OUT AIR MASS.
THURSDAY THROUGH SUNDAY...FROM EARLY MORNING DISCUSSION...
A TROUGH OF LOW PRESSURE WILL DEVELOP OVER THE EASTERN PACIFIC. THIS
MAY DRAW INCREASING MONSOONAL MOISTURE INTO SOUTHERN CALIFORNIA FOR
NEXT WEEKEND INTO EARLY NEXT WEEK WITH SOME CONTINUING MODEL TO
MODEL AND RUN TO RUN DIFFERENCES WITH THE DETAILS AND DEGREE OF THE
POSSIBLE MOISTURE INFLUX. THE CURRENT FORECAST NOW SHOWS SLOWLY
INCREASING POPS FOR THE MOUNTAINS AND DESERTS FOR SATURDAY THROUGH
EARLY NEXT WEEK.
&&
.HYDROLOGY...
FLASH FLOOD THREAT IS LOW TO MODERATE...GROUND BASED GPS
PRECIPITABLE WATER SENSORS ACROSS SW CALIFORNIA SHOW AMOUNTS RANGING
FROM 1.2 INCHES WEST OF THE MOUNTAINS TO 1.6 INCHES OVER THE
MOUNTAINS AND DESERTS. HOWEVER ONLY ONE STATION REPORTED ANY
SIGNIFICANT RAIN EARLY THIS MORNING...HEAPS PEAK ON THE FRONT RANGE
OF THE SAN BERNARDINO MOUNTAINS WITH 0.25 INCHES RAINFALL. ALTHOUGH
RAINSHAFTS WERE OBSERVED OVER THE HIGH DESERTS...RAINFALL AMOUNTS
THERE AS WELL AS ELSEWHERE HAVE GENERALLY BEEN LESS THAN 0.10
INCHES. THESE LOW NUMBERS PROBABLY DUE TO THE TRANSPORT
WINDS...SOUTHEAST WINDS 15-25 MPH IN THE LOWER 15000 FEET...WHICH
DOES NOT ALLOW THE CELLS TO STICK AROUND LONG ENOUGH TO DUMP MUCH
MORE THAN WHAT HAS BEEN OBSERVED SO FAR. STILL HAVE TO WORRY ABOUT
TRAINING OF CELLS AKA SEVERAL CYCLES OF THUNDERSTORMS MOVING ACROSS
THE SAME AREA UNTIL EARLY EVENING HOURS TONIGHT...IF THIS DEVELOPS
WOULD LIKELY PRODUCE FLASH FLOODING EAST/SOUTHEAST SLOPES OF
MOUNTAINS WITH RUNOFF DOWN INTO DESERT VALLEY FLOORS. JUST MODIFIED
THE 11AM THROUGH 11 PM GRIDS TO REFLECT MORE WIDESPREAD
THUNDERSTORMS AND A LITTLE MORE RAIN. EVEN SO...STILL
UNDERFORECASTING SREF POPS BY HALF SO THAT SGX GRIDS DO NOT CLASH
TOO MUCH WITH NEIGHBORING OFFICES. WILL PROBABLY TWEAK A LITTLE MORE
LATER THIS MORNING AND ISSUE ANOTHER QPS/UPDATED ESF.
&&
.AVIATION...
191457Z...COAST/VALLEYS...STRATUS ABOUT 20 SM INLAND...WITH BASES
800-1200 FT MSL AND TOPS 1600-1800 FT MSL...WILL SLOWLY CLEAR TO THE
COAST THROUGH 1900 UTC. 1900-20/0100 UTC...UNRESTRICTED VIS WITH
SCT-FEW CLDS AOA 9000 FT MSL...IN ADDITION TO SCT-BKN CLDS 1200-1500
FT MSL LINGERING WITHIN 5 SM OF THE COAST...POSSIBLY IMPACTING
KSAN...KCRQ AND KSNA WITH BKN CIGS AT TIMES. 20/0100-0700
UTC...STRATUS MOVING BACK INLAND...EVENTUALLY REACHING 20 SM INLAND
BY 20/1400 UTC...WITH BASES AND TOPS SIMILAR TO THIS MORNING.
MTNS/DESERTS...ISOLATED SHOWERS/TSTMS OVER WESTERN SAN BERNARDINO
COUNTY WILL TAPER OFF THROUGH 1700 UTC. HOWEVER...THERE IS ANOTHER
CHANCE OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING OVER
THE RIVERSIDE AND SAN BERNARDINO MTNS AND HIGH DESERTS WITH BASES
NEAR 9000 FT MSL AND TOPS TO 35000 FT MSL. THESE STORMS MAY PRODUCE
SMALL HAIL...STRONG UPDRAFTS...2-5SM VIS IN HEAVY RAIN...AND LOCAL
GUSTY SFC WINDS TO 40 KT. OTHERWISE...SCT-BKN CLDS AOA 9000 FT MSL
AND UNRESTRICTED VIS THROUGH TUESDAY MORNING.
&&
.MARINE...
ASTRONOMICAL HIGH TIDES OF 7 FEET OR GREATER WILL OCCUR DURING THE
EVENINGS THROUGH TUESDAY...INCLUDING A PEAK OF 7.2 FEET THIS
EVENING. SOME VULNERABLE LOW-LYING AREAS ALONG THE COAST MAY
EXPERIENCE SOME MINOR TIDAL OVERFLOW DURING TIMES OF HIGHEST TIDE.
&&
.FIRE WEATHER...
LOT OF DRY LIGHTNING BETWEEN 0400 AND 0800 PDT THIS MORNING...A
CONSERVATIVE COUNT OF 500 STRIKES DURING THIS TIME PERIOD WITH AT
LEAST 9 LIGHTNING STARTED FIRES ON THE SAN BERNARDINO NATIONAL
FOREST. WITH EXCEPTION OF HEAPS PEAK...STATIONS WITH NEARBY
LIGHTNING REPORTED NO RAINFALL OR AMOUNTS LESS THAN 0.10 INCHES.
EXPECT A TEMPORARY BREAK IN THUNDERSTORM ACTIVITY UNTIL 1100 PDT
THEN SCATTERED THUNDERSTORMS OVER MOUNTAINS AND DESERTS...MOVING
NORTH NORTHWEST AROUND 15 MPH. MOST OF THESE SHOULD BE A MIXTURE OF
WET AND DRY...HAVE LAL OF 3 AND 4 FOR REMAINDER OF TODAY/THIS
EVENING. STILL NO WIDESPREAD SIGNIFICANT RAINFALL AMOUNTS EXPECTED
DUE TO SPEED OF MOVEMENT AND DRY LAYER FROM BELOW THUNDERSTORM BASES
AND TOP OF ANY MARINE AIR INFLUENCE...ROUGHLY 10,000 FT TO 2000 FT
MSL....WHICH PRETTY MUCH COVERS ALL OF THE MOUNTAINS AND DESERTS.
FOR TUESDAY AND WEDNESDAY...THE LOW IS MOVING EVER SO SLOWLY TOWARDS
THE NORTHEAST...ASSUMING THE MODELS ARE CORRECT AND IT`S STILL NOT
SITTING IN THE SAME POSITIONS OR FURTHER SOUTH. SO BASED ON MODEL
MOVEMENT SOUTHWEST CALIFORNIA SHOULD BE UNDER MORE STABLE AND
SOMEWHAT DRIER AIRMASS AND PREVAILING SOUTHWEST FLOW. PERHAPS NO
NEW FIRE STARTS BUT A DRIER AND POTENTIALLY BREEZIER PATTERN WOULD
FAN TO LIFE ANY SLEEPERS AND INCREASE FIRE ACTIVITY ACROSS ONGOING
FIRES.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC/FIRE WEATHER...BALFOUR
AVIATION/MARINE...HARRISON
SHORT TERM WARNINGS/STATEMENTS...HARRISON/JJT
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1043 AM MDT MON AUG 19 2013
.UPDATE...
ISSUED AT 1037 AM MDT MON AUG 19 2013
SUNSHINE THIS MORNING WILL PROVIDE GOOD SURFACE HEATING TO START
THE CONVECTIVE CLOUD BUILDUPS OVER THE MTNS BY LATE MORNING. 12Z
MODELS REMAIN HIGHER TERRAIN-CENTRIC WITH THEIR PRECIPITATION
FORECAST THIS AFTERNOON AND EVENING. NOT TOO SURPRISING WITH THE
UPPER RIDGE OVERHEAD AND LIGHT WINDS ALOFT. STORMS THAT DO DEVELOP
THIS AFTERNOON WILL SHOW LITTLE MOVEMENT AND LIKELY COLLAPSE UPON
THEMSELVES FOR THE POTENTIAL OF SOME GUSTY OUTFLOW WINDS AND
ACCENTUATED BY A DRIER SUB-CLOUD LAYER. ONE AREA TO WATCH FOR HEAVY
RAIN POTENTIAL IS SE UT ACROSS THE SW CO. VORTICITY AXIS EXTENDS
ACROSS THIS AREA FROM A WEAK SHORTWAVE MOVING UP THE NV/UT BORDER
AND MAY SERVE AS A BIT OF A FOCUS. THIS ALSO IS AN AXIS OF HIGHER
PRECIPITABLE WATER ESTIMATES OF 0.8 TO 1.0 INCH. WILL ADJUST POPS
UPWARDS A BIT FOR SE UT/SW CO THIS AFTERNOON AS A RESULT.
UPDATE ISSUED AT 830 AM MDT MON AUG 19 2013
QUICK UPDATE TO THE GRIDDED FORECAST TO BETTER REFLECT THE CURRENT
SUNNY/MOSTLY SUNNY CONDITIONS ACROSS MOST OF FORECAST AREA EARLY
THIS MORNING. EXCEPTION IS SOME ALTOCUMULUS CLOUDS OVER SE UT LEFT
OVER FROM LAST NIGHT AND WHERE THE RAP MODEL PUTS A WEAK VORTICITY
MAX. CURRENT FORECAST FOR THIS AFTERNOON SEEMS ON TRACK PER QUICK
LOOK AT THE LATEST RAP/HRRR MODELS.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
300 AM MDT MON AUG 19 2013
HIGH PRESSURE WILL REMAIN ANCHORED OVER THE REGION FOR THE NEXT
SEVERAL DAYS. MOISTURE WORKING NORTHWARD WILL BRING ANOTHER ROUND
OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING...WITH THE
FOCUS TODAY GENERALLY SOUTH OF INTERSTATE 70. STORMS WILL
INITIALLY FIRE ALONG THE HIGHER TERRAIN...WITH ACTIVITY DRIFTING
OFF OVER THE VALLEYS LATE THIS AFTERNOON AND EVENING...WITH AN
EMPHASIS ON DRIFT. WINDS ALOFT WILL BE WEAK WITH THE RIDGE
DIRECTLY OVERHEAD AND POTENTIAL FOR LOCALLY HEAVY RAINFALL WILL BE
UP A BIT WITH SLOW STORM MOTIONS. TEMPERATURES WILL BE RUNNING
NEAR SEASONAL NORMS WITH LIGHT WINDS OUTSIDE OF CONVECTIVE GUSTS
TO NEAR 40 MPH WITH THE STRONGER STORMS.
A STRONGER SURGE OF SUBTROPICAL MOISTURE CONTINUES TO WORK INTO
THE GREAT BASIN AND THEN LEAKS EASTWARD INTO TUESDAY FOR AN UPTURN
IN SHOWERS AND THUNDERSTORMS. THE SHEARED ENERGY FROM THE BAJA
DISTURBANCE IS PROGGED TO STAY WELL WEST OF THIS CWA WITH TIME
HEIGHT SECTIONS SHOWING LITTLE ORGANIZED DYNAMICAL LIFT. STILL
PRECIPITABLE WATER VALUES CLIMB TO AN INCH OVER EASTERN UTAH AND
FAR WESTERN COLORADO. BROKEN TO OVERCAST SKIES MAY LIMIT OR DELAY
AFTERNOON HEATING AND INSTABILITY SOMEWHAT. SLOW STORM MOTION WILL
PRODUCE LOCALLY HEAVY RAIN AND POTENTIAL RUNOFF PROBLEMS. A
RELATIVELY DRY NEAR- SURFACE LAYER WILL ALSO ASSIST WITH ENHANCED
LOCAL OUTFLOW WINDS.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
300 AM MDT MON AUG 19 2013
BOUNDARY INTERACTION MAY PRODUCE ISOLATED NOCTURNAL CONVECTION
INTO WEDNESDAY MORNING. THE 593 HIGH REBOUNDS WESTWARD BACK TO
NEAR THE FOUR CORNERS. BOTH THE GFS AND NAM ERODE PRECIPITABLE
WATER VALUES SOMEWHAT UNDER THE HIGH. SUBSIDENCE WILL ALSO CAP
LATE DAY CONVECTION A BIT COMPARED TO TUESDAY. STILL ALL MTN
RANGES WILL LIKELY FIRE SOME AFTERNOON STORMS. STORM MOTION
REMAINS SLOW FOR A CONTINUED THREAT OF LOCALLY HEAVY SHOWERS.
MOISTURE WORKING NORTHWARD ALONG THE WESTERN EDGE OF HIGH PRESSURE
CENTERED ACROSS THE CENTRAL PLAINS WILL KEEP CONDITIONS UNSETTLED
AS WE MOVE THROUGH THE WEEK AND INTO THE WEEKEND. HARD TO PIN
POINT ANY INDIVIDUAL WAVE IN THIS PATTERN FOR ENHANCED
POTENTIAL...SO FOR NOW WILL CONTINUE WITH THE BROAD BRUSH APPROACH
OF DAILY CONVECTION...PRIMARILY FOCUSED ON THE AFTERNOON AND
EVENING HOURS. TEMPERATURES WILL BE RUNNING NEAR SEASONAL NORMS
THROUGH THE PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1037 AM MDT MON AUG 19 2013
SCATTERED SHOWERS AND THUNDERSTORMS WILL AGAIN DEVELOP ACROSS
EASTERN UTAH AND WESTERN COLORADO THIS AFTERNOON AND EVENING. THE
STORMS WILL BE MOST NUMEROUS SOUTH AND EAST OF A LINE FROM K4HV TO
KEGE...ESPECIALLY BETWEEN 20Z THIS AFTERNOON AND 03Z THIS EVENING.
OUTSIDE OF THIS WINDOW...STORMS WILL BE MORE ISOLATED IN NATURE.
EXPECT BRIEF HEAVY RAIN...SMALL HAIL AND GUSTY OUTFLOW WINDS TO 40
MPH IN THE VICINITY OF SHOWERS WITH BRIEF MOUNTAIN OBSCURATIONS
POSSIBLE. STORMS DISSIPATE AFTER 03Z THIS EVENING WITH VFR CONDS
PREVAILING AT ALL TERMINAL SITES.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
UPDATE...JAD
SHORT TERM...JDC/JOE
LONG TERM...JOE/JDC
AVIATION...TGJT
AREA FORECAST DISCUSSION
NWS POCATELLO ID
222 PM MDT MON AUG 19 2013
.DISCUSSION...STRONG UPPER LOW REMAINS OFF CALIFORNIA COAST WITH
MOISTURE STREAMING NORTH THROUGH GREAT BASIN. SHORTWAVE AXIS HAS
MOVED THROUGH PANHANDLE INTO MONTANA EARLY THIS AFTERNOON...WHICH
HAS KEPT MOISTURE SURGE LIMITED. CONVECTION SO FAR LIMITED TO
AREAS SOUTH OF STATE LINE BUT HAVE LEFT WEAK POPS NORTH OF BORDER
INTO SOUTHERN HIGHLANDS FOR OVERNIGHT. HRRR PUSHES CONVECTION
NORTH INTO THE REGION BY LATE AFTERNOON THEN SLOWLY SPREADS
NORTHEAST AFTER MIDNIGHT. GFS LENDS SUPPORT TO THIS IDEA BUT NAM
LESS SO. MOISTURE SURGE CONTINUES INTO MIDWEEK WITH STRONG
GRADIENT LAYING ACROSS EASTERN IDAHO MIDDAY TUESDAY...THEN
GRADIENT PUSHING WELL NORTH OF FORECAST AREA FOR WEDNESDAY AND
BEYOND. STILL SOME QUESTION AS TO HOW FAR NORTH CONVECTION WILL
PUSH ON TUESDAY AFTERNOON WITH SUBSEQUENT IMPACT ON FIRE
HEADLINES. SEE DISCUSSION BELOW. OTHERWISE BEST CHANCE FOR
SIGNIFICANT COVERAGE OF STORMS APPEARS TO BE ON WEDNESDAY WITH PW
OVER AN INCH MOST AREAS. COULD SEE LOCALLY HEAVY RAINFALL AND WILL
NOT BE SURPRISED IF FLASH FLOOD WATCH MAY BE NECESSARY IN ADDITION
TO RED FLAG FOR FIRE CONCERNS...ESPECIALLY IN VICINITY OF RECENT
BURN SCARS LIKE BEAVER CREEK/LODGEPOLE/STATE FIRES IN
URBAN/WILDLAND INTERFACE AREAS. BOTH GFS AND ECMWF CONTINUE IDEA
OF WEAKENING UPPER LOW WEDNESDAY NIGHT INTO THURSDAY AND EJECTING
LOW NORTHEAST THROUGH PACNW/PANHANDLE ON FRIDAY. SOME IDEA OF A
DRY SLOT ON FRIDAY...THEN SOUTH FLOW CONTINUES THROUGH THE GREAT
BASIN INTO EASTERN IDAHO THROUGH THE REMAINDER OF THE WEEKEND WITH
STRONG HIGH OVER GREAT PLAINS AND AMPLIFYING TROUGH JUST OFF
PACIFIC COAST. WILL KEEP SOME MENTION OF THUNDERSTORMS OVER HIGHER
ELEVATIONS FRIDAY THROUGH THE WEEKEND. DMH
&&
.AVIATION...SMOKE AT KSUN WILL CONTINUE TO BE THE GREATEST IMPACT.
LOOK FOR IFR VISIBILITIES AGAIN TONIGHT THROUGH TOMORROW MORNING.
LOOK FOR ISOLATED THUNDERSTORMS ACROSS OUR SOUTHERN AREAS LATE THIS
AFTERNOON INTO EARLY EVENING BRINGING VICINITY THUNDERSTORMS FOR
KBYI AND TO AN LESSER EXTENT KPIH. TOMORROW AFTERNOON LOOK FOR A
BETTER CHANCE FOR VICINITY THUNDERSTORMS PARTICULARLY FOR KBYI AND
KSUN. WYATT
&&
.FIRE WEATHER...A RED FLAG HAS BEEN CONTINUED FOR ZONE 475 THROUGH
EARLY THIS EVENING. RELATIVE HUMIDITY HAS ALREADY GONE BELOW 15 PERCENT
WITH WINDS IN THE UPPER TEENS TO LOWER TWENTIES. FIRE ZONES 422 AND
475 ARE RUNNING SLIGHTLY STRONGER WINDS BUT HAVE SLIGHTLY HIGHER
RELATIVE HUMIDITY WITH MOISTURE MOVING UP FROM THE SOUTH. EXPECT
AFTERNOON ISOLATED THUNDERSTORMS ACROSS THE SOUTHERN HIGHLANDS
TODAY. A FIRE WEATHER WATCH FOR SCATTERED SHOWERS AND THUNDERSTORMS
IS CONTINUED FOR TUESDAY AFTERNOON THROUGH THURSDAY. HAVE HELD OFF
ON UPGRADING TO A RED FLAG FOR TUESDAY AS IT LOOKS MARGINAL FOR
SCATTERED AFTERNOON THUNDERSTORMS AT THIS POINT. WEDNESDAY AND
THURSDAY AFTERNOONS STILL LOOK LIKE A RED FLAG WARNING WILL BE
NEEDED FOR SCATTERED TO NUMEROUS THUNDERSTORMS. A FLASH FLOOD WATCH
FOR WEDNESDAY AFTERNOON MAY BE NEEDED AS WELL FOR THE MOUNTAIN ZONES
PARTICULARLY FOR RECENT BURN AREAS. MODELS SHOW SLIGHT THUNDERSTORM
CHANCES FOR OUR NORTHERN AREAS FRIDAY AFTERNOON IN SOUTHWEST FLOW.
SATURDAY LOOKS SLIGHTLY DRIER BEFORE ANOTHER SYSTEM STARTS TO
APPROACH THE AREA BRINGING BACK BETTER PRECIPITATION CHANCES FOR
SUNDAY AND MONDAY. WYATT
&&
.AIR STAGNATION...AREAS OF SMOKE WILL REMAIN IN THE FORECAST OVER
THE CENTRAL MOUNTAINS WHILE LARGE FIRES CONTINUE TO BURN.
INCREASING MOISTURE OVER THE NEXT FEW DAYS WILL ALLOW
THUNDERSTORMS TO FORM. OVERALL IMPACT TOUGH TO SAY WITH POTENTIAL
FOR BOTH NEW STARTS DUE TO LIGHTNING AND LOCALLY HEAVY RAIN WHICH
MAY HELP CURRENT FIRE SITATION. IDAHO DEQ HAS LIFTED AIR QUALITY
STATEMENT FOR CUSTER COUNTY WHILE CONTINUING FOR BLAINE AND HAVE
ISSUED UPDATED STATEMENTS. DMH
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH THURSDAY
EVENING IDZ413-427.
FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH THURSDAY
EVENING IDZ410-425.
RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING IDZ475.
FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH THURSDAY
EVENING IDZ422-475-476.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
208 PM MDT MON AUG 19 2013
.SHORT TERM...(TONIGHT THROUGH TUESDAY AFTERNOON)
ISSUED AT 203 PM MDT MON AUG 19 2013
AS OF 3 PM CDT...2 PM MDT...SKIES ACROSS THE TRI-STATE AREA WERE
CLEAR. TEMPERATURES HAVE RESPONDED NICELY WITH THE LACK OF CLOUD
COVER AND RANGED FROM THE MID 80S TO LOW 90S. WINDS WERE FROM THE
SOUTHEAST AT 10 TO 15 MPH WITH GUSTS TO 20 MPH. THE RIDGE OF HIGH
PRESSURE OVER THE SOUTHWEST HAS STRENGTHENED SOME TODAY. SUBSIDENCE
ALOFT WAS ENTRENCHED OVER THE REGION AT THIS TIME.
FOR THE REST OF TODAY AND TONIGHT...WITH THE INFLUENCE OF THE RIDGE
AND SUBSIDENCE ALOFT FIRMLY IN PLACE...PRECIPITATION CHANCES WILL BE
NEAR ZERO. THE HRRR KEEPS SUGGESTING A ISOLATED SHOWER OR STORM IS
POSSIBLE OVER CHEYENNE COUNTY COLORADO BUT NO OTHER MODEL IS
PRODUCING PRECIPITATION OVER THE FORECAST AREA. TEMPERATURES FOR
TONIGHT ARE EXPECTED TO FALL INTO THE LOW 60S UNDER MOSTLY CLEAR
SKIES. LIGHT WINDS AND SOME LINGERING LOW LEVEL MOISTURE MAY ALLOW
FOR SOME PATCHY LIGHT FOG TO FORM...MAINLY ACROSS SOUTHWEST
NEBRASKA. DID NOT THINK THIS WAS WORTHY OF A MENTION IN THE GRIDS AS
VISIBILITIES SHOULD NOT FALL LOWER THAN 4 MILES AT WORSE.
FOR TOMORROW...THE RIDGE OF HIGH PRESSURE WILL STRENGTHEN SLIGHTLY
AGAIN. MODELS PROJECT THAT 850 MB TEMPERATURES WILL WARM A DEGREE OR
TWO OVER TODAYS 850 TEMPS SO A SIMILAR RESPONSE IS EXPECTED IN
SURFACE TEMPERATURES. AS A RESULT...HIGH TEMPERATURES IN THE MID TO
UPPER 90S ARE FORECAST UNDER CLEAR SKIES. SOUTH TO SOUTHEAST WINDS
WILL CONTINUE AS A LEE TROUGH TO THE WEST WILL CONTINUE TO INFLUENCE
THE LOW LEVEL FLOW. BASED ON THE UPPER LEVEL PATTERN AND THE LACK OF
A STRONG DISTURBANCE...PRECIPITATION IS NOT FORECAST FOR TOMORROW.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 203 PM MDT MON AUG 19 2013
THE UPPER HIGH CURRENTLY OVER COLORADO/ARIZONA IS FORECAST TO
MOVE EAST TO KANSAS/OKLAHOMA BY THE END OF THE WEEK AND
ULTIMATELY WIND UP OVER ILLINOIS BY THE END OF THE PERIOD. THIS
WILL BE THE PRIMARY FEATURE AFFECTING THE WEATHER...AND IN GENERAL
THIS WILL TRANSLATE INTO A WARM AND DRY PERIOD FOR THE FORECAST
AREA.
ONE POSSIBLE CAVEAT TO THE DRY SCENARIO MENTIONED ABOVE WILL BE A
WEAK SHORT WAVE TROUGH FORECAST BY THE NAM AND GFS TO RIDE OVER
THE TOP OF THE RIDGE WEDNESDAY NIGHT. BOTH MODELS INDICATE A
CHANCE FOR SCATTERED CONVECTION WED NIGHT WHILE THE ECMWF KEEPS
THINGS DRY AND THE GEM SHOWS CONVECTION JUST NORTH OF THE AREA.
FOR NOW HAVE KEPT PREVIOUS FORECAST OF LOW CHANCE POPS DURING THIS
TIME WITH AN EMPHASIS ON THE NORTHWEST AND CENTRAL COUNTIES.
TEMPERATURES WILL BE ABOVE NORMAL IN THE LOW-MID 90S FOR MUCH OF
THE PERIOD WHICH IS 5-8 DEGREES ABOVE NORMAL...WHILE LOWS REMAIN
GENERALLY IN THE 60S.
AT THE END OF THE PERIOD AND INTO THE MIDDLE OF NEXT WEEK WHEN THE
UPPER HIGH HAS SHIFTED EAST...THERE WILL BE AN INCREASING WINDOW
OF OPPORTUNITY FOR SCATTERED CONVECTION AS THE AREA COMES UNDER
MORE OF A WEAK SOUTHWEST FLOW ALOFT. UNTIL THEN...PRECIP CHANCES
LOOK MEAGER.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1125 AM MDT MON AUG 19 2013
AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL CONTINUE TO DOMINATE
THE WEATHER PATTERN FOR THE NEXT 24 HOURS. THIS RIDGE SHOULD
SUPPRESS ANY POSSIBLE SHOWER OR THUNDERSTORM ACTIVITY. A SLIGHT
DECREASE IN LOW LEVEL MOISTURE IS EXPECTED TONIGHT AND WITH DRIER
AIR ALOFT. THINKING THAT FOG CHANCES ARE TOO SMALL TO MENTION IN
THE KGLD TAF. FOG WAS INDICATED IN THE MAV...MET AND LAV GUIDANCE
FOR KMCK SO HAVE INTRODUCED A BRIEF PERIOD OF MVFR VISIBILITIES.
LIGHT SOUTH WINDS WILL CONTINUE THROUGHOUT THE TAF PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...RRH
LONG TERM...DLF
AVIATION...RRH
AREA FORECAST DISCUSSION
NWS GOODLAND KS
205 PM MDT MON AUG 19 2013
.SHORT TERM...(TONIGHT THORUGH TUESDAY AFTERNOON)
ISSUED AT 203 PM MDT MON AUG 19 2013
AS OF 3 PM CDT...2 PM MDT...SKIES ACROSS THE TRI-STATE AREA WERE
CLEAR. TEMPERATURES HAVE RESPONDED NICELY WITH THE LACK OF CLOUD
COVER AND RANGED FROM THE MID 80S TO LOW 90S. WINDS WERE FROM THE
SOUTHEAST AT 10 TO 15 MPH WITH GUSTS TO 20 MPH. THE RIDGE OF HIGH
PRESSURE OVER THE SOUTHWEST HAS STRENGTHENED SOME TODAY. SUBSIDENCE
ALOFT WAS ENTRENCHED OVER THE REGION AT THIS TIME.
FOR THE REST OF TODAY AND TONIGHT...WITH THE INFLUENCE OF THE RIDGE
AND SUBSIDENCE ALOFT FIRMLY IN PLACE...PRECIPITATION CHANCES WILL BE
NEAR ZERO. THE HRRR KEEPS SUGGESTING A ISOLATED SHOWER OR STORM IS
POSSIBLE OVER CHEYENNE COUNTY COLORADO BUT NO OTHER MODEL IS
PRODUCING PRECIPITATION OVER THE FORECAST AREA. TEMPERATURES FOR
TONIGHT ARE EXPECTED TO FALL INTO THE LOW 60S UNDER MOSTLY CLEAR
SKIES. LIGHT WINDS AND SOME LINGERING LOW LEVEL MOISTURE MAY ALLOW
FOR SOME PATCHY LIGHT FOG TO FORM...MAINLY ACROSS SOUTHWEST
NEBRASKA. DID NOT THINK THIS WAS WORTHY OF A MENTION IN THE GRIDS AS
VISIBILITIES SHOULD NOT FALL LOWER THAN 4 MILES AT WORSE.
FOR TOMORROW...THE RIDGE OF HIGH PRESSURE WILL STRENGTHEN SLIGHTLY
AGAIN. MODELS PROJECT THAT 850 MB TEMPERATURES WILL WARM A DEGREE OR
TWO OVER TODAYS 850 TEMPS SO A SIMILAR RESPONSE IS EXPECTED IN
SURFACE TEMPERATURES. AS A RESULT...HIGH TEMPERATURES IN THE MID TO
UPPER 90S ARE FORECAST UNDER CLEAR SKIES. SOUTH TO SOUTHEAST WINDS
WILL CONTINUE AS A LEE TROUGH TO THE WEST WILL CONTINUE TO INFLUENCE
THE LOW LEVEL FLOW. BASED ON THE UPPER LEVEL PATTERN AND THE LACK OF
A STRONG DISTURBANCE...PRECIPITATION IS NOT FORECAST FOR TOMORROW.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 203 PM MDT MON AUG 19 2013
THE UPPER HIGH CURRENTLY OVER COLORADO/ARIZONA IS FORECAST TO
MOVE EAST TO KANSAS/OKLAHOMA BY THE END OF THE WEEK AND
ULTIMATELY WIND UP OVER ILLINOIS BY THE END OF THE PERIOD. THIS
WILL BE THE PRIMARY FEATURE AFFECTING THE WEATHER...AND IN GENERAL
THIS WILL TRANSLATE INTO A WARM AND DRY PERIOD FOR THE FORECAST
AREA.
ONE POSSIBLE CAVEAT TO THE DRY SCENARIO MENTIONED ABOVE WILL BE A
WEAK SHORT WAVE TROUGH FORECAST BY THE NAM AND GFS TO RIDE OVER
THE TOP OF THE RIDGE WEDNESDAY NIGHT. BOTH MODELS INDICATE A
CHANCE FOR SCATTERED CONVECTION WED NIGHT WHILE THE ECMWF KEEPS
THINGS DRY AND THE GEM SHOWS CONVECTION JUST NORTH OF THE AREA.
FOR NOW HAVE KEPT PREVIOUS FORECAST OF LOW CHANCE POPS DURING THIS
TIME WITH AN EMPHASIS ON THE NORTHWEST AND CENTRAL COUNTIES.
TEMPERATURES WILL BE ABOVE NORMAL IN THE LOW-MID 90S FOR MUCH OF
THE PERIOD WHICH IS 5-8 DEGREES ABOVE NORMAL...WHILE LOWS REMAIN
GENERALLY IN THE 60S.
AT THE END OF THE PERIOD AND INTO THE MIDDLE OF NEXT WEEK WHEN THE
UPPER HIGH HAS SHIFTED EAST...THERE WILL BE AN INCREASING WINDOW
OF OPPORTUNITY FOR SCATTERED CONVECTION AS THE AREA COMES UNDER
MORE OF A WEAK SOUTHWEST FLOW ALOFT. UNTIL THEN...PRECIP CHANCES
LOOK MEAGER.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1125 AM MDT MON AUG 19 2013
AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL CONTINUE TO DOMINATE
THE WEATHER PATTERN FOR THE NEXT 24 HOURS. THIS RIDGE SHOULD
SUPPRESS ANY POSSIBLE SHOWER OR THUNDERSTORM ACTIVITY. A SLIGHT
DECREASE IN LOW LEVEL MOISTURE IS EXPECTED TONIGHT AND WITH DRIER
AIR ALOFT. THINKING THAT FOG CHANCES ARE TOO SMALL TO MENTION IN
THE KGLD TAF. FOG WAS INDICATED IN THE MAV...MET AND LAV GUIDANCE
FOR KMCK SO HAVE INTRODUCED A BRIEF PERIOD OF MVFR VISIBILITIES.
LIGHT SOUTH WINDS WILL CONTINUE THROUGHOUT THE TAF PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...RRH
LONG TERM...DLF
AVIATION...RRH
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
132 PM EDT Mon Aug 19 2013
...Updated Aviation Discussion...
...Forecast Update...
Issued at 1107 AM EDT Mon Aug 19 2013
Fog continues to mix out across the southern forecast area this
morning. In most locations, the fog has transitioned over to a low
stratus deck which will take some time to mix out more fully. We
expect that to occur around lunch time or early this afternoon. Cu
field has become better defined across southern KY this morning
despite having a bit more capping aloft. A few isolated showers
will be possible mainly along and SE of the BG Parkway. Additional
isolated showers/storms will be possible later this afternoon.
Forcing is fairly weak from a dynamical standpoint, but differential
heating is probably going to be main forcing mechanism this
afternoon. Temperatures are currently in the lower 70s across the
south, with a belt of mid-upper 70s along and just north of the Ohio
River. Obviously the thicker cloud cover to the south will augment
the solar insolation a bit this afternoon which will likely lead to
a N-S temperature gradient. Highs in the 80-85 degree range in
areas from the KY Parkways and northward still look good. Lower 80s
down across the south and southeastern sections are still
attainable, but will probably occur a little later in the afternoon
due to the cloud cover delaying insolation.
Update issued at 530 AM EDT Mon Aug 19 2013
Updated the forecast to remove areas of fog with patchy dense fog
from southeast Indiana and the Bluegrass region of KY. Mid level
clouds and lesser low level moisture than central and southern KY
(where patches of dense fog have been reported) have limited fog
formation over southeast Indiana and the Bluegrass. Downgraded this
area to just patchy fog for the rest of the pre-dawn hours.
Issued an SPS for portions of south and central KY where patchy
dense fog has been reported and where it rained yesterday (which
should be fog prone). Few-sct mid level clouds continue to move
over this area improving fog at times so feel dense fog coverage
will remain patchy.
.SHORT TERM (Now through Tuesday)...
Issued at 330 AM EDT Mon Aug 19 2013
The main forecast concern in the short term will be fog this
morning. A very moist low level atmosphere along with very light or
nearly calm winds have created an ideal environment for fog
formation which we`ve already seen develop in our area. The worst
fog spots remain over southern IL/western KY and over southwest
Ohio. The 5Z RAP model has these fog areas handled well and expect
them to expand into central KY and portions of southeast IN. Low
clouds will also accompany the fog as soundings indicate a shallow
layer of trapped moisture under a weak inversion. With these
thoughts in mind, think that most locations over southern IN and
central KY will see areas of fog this morning. Some locations over
central KY and southeast IN will probably see patches of dense fog
as well assuming the low clouds don`t inhibit fog density too much.
Will highlight the patchy dense fog in the HWO this morning and
monitor closely in case it becomes more widespread and an SPS or
dense fog advisory is need.
For the rest of the day, fog should burn off fairly quickly after
sunrise. With an upper trough passing through the region, can`t
rule out an isld shower over portions of south and east central KY.
However, did scale the area of potential precip back a bit. High
temperatures should reach the low to mid 80s this afternoon.
Tonight a second upper trough will settle into the mid Mississippi
River Valley. Some fog may be possible but not as widespread as
this morning. Will continue inherited patchy fog mainly in river
valleys. Lows tonight will be in the mid 60s.
For Tues, expect a 20% chance of showers/t-storms to expand from
south to north over the area throughout the day as a vort wave on
the eastern side of the upper trough push north through our area.
Any convection would be on the weak side. Tuesday afternoon high
temps should be in the low to mid 80s with southern Indiana being
the hottest due to a longer period of sunshine before clouds/isld
convection move in.
.LONG TERM (Tuesday Night through Sunday)...
Issued at 311 AM EDT Mon Aug 19 2013
The models have finally come into agreement with a mid-level low
that forms over the Ohio Valley at the start of this forecast
period. This cutoff low hangs out in the region through Thursday
night when it undergoes a transformation into an open wave in
response to an approaching shortwave. This shortwave rides around
the periphery of a stout ridge building in over the Plains and looks
to exit the forecast area by early Saturday. The ridge continues to
build in from the west, giving us dry conditions through the end of
the weekend and into early next week.
Tuesday night through Thursday:
For this issuance, have introduced slight chance PoPs for Tuesday
night as the low establishes itself overhead and surface southerly
flow allows for moisture to be pulled in. Chance PoPs continues for
Wednesday as daytime heating assists in convection across the area.
With the loss of daytime heating and in conjunction with general
model consensus, have kept PoPs out overnight Wednesday into early
Thursday. As the low is depicted to begin traversing eastward
Thursday, have only slight chance during the day with the primary
focus for possible convection more toward eastern KY. The models
have the low slowly but surely progressing eastward during this time
frame and am a little skeptical on its speed. How quickly the low
exits will depend on the timing of a weak frontal boundary
attempting to lay out across the southern Great Lakes by Thursday
night.
Thursday night through Friday night:
Have gone with slight chance PoPs strictly across the northern
sections as the alluded to frontal boundary approaches from the
north. The front stalls well to our north and does not currently
appear to be a factor for us beyond Friday. The aforementioned
shortwave swings around the region Friday, hence the slight to
chance PoPs under diurnally-driven conditions. Again, skepticism
sets in for the timing of it all as it seems to really move through
a little too quickly. For now, have kept the area dry Friday night
until a better handle on the progression of everything plays out.
Temperatures will be more difficult to predict Tuesday night through
Friday night as cloudy skies and/or rain will obviously wreck havoc.
What can be said with confidence is that highs will continue to run
slightly below normal and lows will flirt with normal.
Saturday through Sunday:
With that ridge building in, we`ll begin to see real signs of summer
return as temperatures look to rebound back toward normal and partly
to mostly sunny skies prevail.
&&
.AVIATION (18Z TAF Update)...
Issued at 131 PM EDT Mon Aug 19 2013
VFR conditions are expected through much of the period. Some
scattered showers and storms will be possible this afternoon across
the Bluegrass region that could affect the KLEX area. For now, will
carry a VCSH group through the afternoon. Surface winds are
expected to be light and variable. VFR conditions are expected this
evening and into the overnight period. However, guidance suggests
fog is likely again at KBWG and KLEX, so will carry some tempo IFR
vsbys between 20/08-12Z at KBWG and KLEX. KSDF should remain VFR
overnight with some patchy haze possible toward 20/12Z.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........MJ
Short Term.....AMS
Long Term......lg
Aviation.......MJ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
422 PM EDT MON AUG 19 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 422 PM EDT MON AUG 19 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW ACROSS MUCH OF
SRN CANADA. SHORTWAVE TROF THAT WAS OVER MT/SRN SASKATCHEWAN 24HRS
AGO IS NOW OVER THE UPPER LAKES THOUGH MUCH OF THE ENERGY APPEARS TO
BE SETTLING SSE INTO THE WEAKENING REMNANT OF THE TROF THAT HAS BEEN
OVER THE LOWER MISSISSIPPI VALLEY THE LAST FEW DAYS. WAVE PRODUCED A
CLUSTER OF SHRA/TSRA OVER WRN LAKE SUPERIOR THIS MORNING. THE SHRA
RAPIDLY DIMINISHED AS THEY APPROACHED WRN UPPER MI AND DISSIPATED
SOON AFTER REACHING THAT AREA. SO...FAR NO NEW SHRA/TSRA HAVE
DEVELOPED WITH DAYTIME HEATING.
LATEST SPC MESOANALYSIS SHOWS MLCAPE OF 500-1000J/KG OVER ROUGHLY
THE W HALF OF UPPER MI. VIS SATELLITE IMAGERY SHOWS CU DEVELOPING
OVER THE LAST COUPLE OF HRS...AND LATEST OBS ALONG THE SHORE
INDICATE LAKE BREEZE JUST BEGINNING TO DEVELOP OFF LAKE SUPERIOR.
PERHAPS A FEW SHRA/TSRA MAY YET DEVELOP OVER THE NEXT COUPLE OF HRS
AS LAKE BREEZE MAKES SOME INLAND PROGRESS. SINCE LATEST HIGH RES
RAPID REFRESH MODEL STILL GENERATES SOME CONVECTION OVER THE NCNTRL
LATE THIS AFTN...WILL HOLD ONTO SCHC POPS FOR THE NEXT SEVERAL HRS.
IF ANY SHRA/TSRA DO DEVELOP...THEY WILL DISSIPATE WITH LOSS OF
DAYTIME HEATING...ESPECIALLY SINCE HEIGHTS ARE IN THE PROCESS OF
STEADILY RISING AND DEEP LAYER QVECTOR DIVERGENCE IS DEVELOPING.
THERE IS SOME THETA-E ADVECTION OVERNIGHT...AND THE GEM SUGGESTS
SOME ISOLD CONVECTION LATE TONIGHT/TUE MORNING AT LEADING EDGE OF
THETA-E AXIS APPROACHING WRN UPPER MI. HOWEVER...WITH 850MB WINDS
ANTICYCLONIC AND NOT MUCH OF A LOW-LEVEL JET...POTENTIAL OF ANY
ISOLD CONVECTION LATE SEEMS VERY UNLIKELY. WILL CARRY DRY FCST THRU
THE OVERNIGHT. ALTHOUGH SKIES WILL TURN MOSTLY CLEAR...A LIGHT BUT
STEADY SW WIND AND INCREASED COLUMN MOISTURE WILL WORK TO LIMIT THE
DIURNAL TEMP FALL. UNDER S TO SW WINDS...THE HIGHEST MIN TEMPS WILL
BE IN THE DOWNSLOPE AREAS NEAR LAKE SUPERIOR OVER THE W HALF. EXPECT
MINS IN THE MID 60S THERE. INLAND...MID 50S TO AROUND 60F SHOULD BE
THE RULE.
ON TUE...PRES GRADIENT TIGHTENS A BIT BTWN SFC HIGH OVER THE MID
ATLANTIC STATES AND A LOW PRES TROF MOVING ACROSS THE NRN
PLAINS/SCNTRL CANADA. STRENGTHENING SW FLOW WILL BRING AN INCREASE
IN LOW-LEVEL DWPTS TUE...RESULTING IN A MUCH MORE UNCOMFORTABLE DAY.
MIXING TOWARD 800MB ON FCST SOUNDINGS SUGGESTS MAX TEMPS EASILY INTO
THE MID/UPPER 80S. STRONGER SW WINDS WILL PREVENT LAKE BREEZE
DEVELOPMENT OFF LAKE SUPERIOR AND SHOULD LEAD TO SOME OF THE
WARMEST READINGS IN THE DOWNSLOPE AREAS NEAR THE LAKE. EXPECT SOME
LOCATIONS TO REACH OR JUST EXCEED 90F. S/SW WINDS WILL KEEP
CONDITIONS COOLER NEAR LAKE MICHIGAN. COMBINATION OF TEMPS WELL INTO
THE 80S AND HIGHER DWPTS INTO THE 60S WILL MAKE TUE THE MOST
UNCOMFORTABLE DAY SINCE THE HOT WEATHER STRETCH IN MID JULY. NAM
SHOWS MLCAPE INCREASING TO 2000-3000J/KG TUE AFTN WHILE THE GFS IS
LOWER IN THE 1000-2000J/KG RANGE. LACK OF LAKE BREEEZE DEVELOPMENT
OFF LAKE SUPERIOR WILL BE ONE MISSING FORCING MECHANISM TO TRIGGER
CONVECTION. SINCE THERE ARE HINTS OF A SUBTLE SHORTWAVE MOVING
TOWARD THE UPPER LAKES...OPTED TO MAINTAIN SCHC POPS OVER PORTIONS
OF CNTRL UPPER MI WHERE THERE IS SOME LOW-LEVEL CONVERGENCE AS A
RESULT OF LAKE MICHIGAN LAKE BREEZE COMPONENT. IN THE ABSENCE OF ANY
SHORTWAVE...TUE WILL LIKELY END UP DRY ACROSS THE BOARD.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 422 PM EDT MON AUG 19 2013
NORTHERN STREAM UPPER TROUGH WILL SLIDE THROUGH THE AREA DURING
THE FIRST PART OF THE LONG TERM PERIOD AND LEAD TO A DECENT CHANCE
OF RAIN OVER THE AREA WEDNESDAY.
FIRST FOR TUESDAY NIGHT...THERE MAY BE SOME SHOWERS/THUNDERSTORMS
OVER LAKE SUPERIOR ON AHEAD OF THE COLD FRONT. THIS A CONTINUATION
OF THE CONVECTION THAT DEVELOPS IN SOUTHWEST ONTARIO AND NORTHEAST
MINNESOTA FROM THE AFTERNOON AND A WEAK SHORTWAVE MOVING EAST
ACROSS LAKE SUPERIOR. IN ADDITION...THIS IS ALSO THE AREA OF THE
STRENGTHENING LOW LEVEL JET AND 850-700MB THERMAL RIDGE. WITH STORM
MOTIONS TO THE EAST...WOULD THINK ISLE ROYALE AND NORTHERN LAKE
SUPERIOR WOULD HAVE THE BEST SHOT OF SEEING PRECIPITATION...BUT IT
COULD BRUSH THE KEWEENAW PENINSULA.
ON WEDNESDAY...THE MAIN SHORTWAVE WILL BE MOVING THROUGH SOUTHWEST
ONTARIO AND BE DISCONNECTED FROM THE COLD FRONT MOVING EAST ACROSS
WESTERN LAKE SUPERIOR ON WEDNESDAY MORNING. BUT...THERE ARE HINTS
THAT A SECOND WEAKER WAVE WILL BE SLIDING EAST ACROSS NORTHERN
WISCONSIN AND WESTERN UPPER MICHIGAN IN THE AFTERNOON. IF THIS
OCCURS...IT WOULD ASSIST WITH CONVECTIVE DEVELOPMENT AS THE COLD
FRONT MOVES THROUGH WESTERN/CENTRAL U.P. DURING THE DAY WEDNESDAY.
MODELS SEEM TO HAVE SPED IT UP A TOUCH WITH IT MOVING THROUGH THE
WESTERN U.P. IN THE LATE MORNING OR EARLY AFTERNOON AND THEN THE
CENTRAL U.P. IN THE MID AFTERNOON HOURS. IT THEN EXITS THE AREA
OVER LAKE MICHIGAN DURING THE EVENING. WITH THE WARM...HUMID
AIRMASS...INSTABILITY WILL BE PRETTY GOOD FOR U.P. STANDARDS (MLCAPE
VALUES OF 1500-3000 J/KG DEPENDING ON THE MODEL) WHICH ARE AIDED BY
STEEP MID LEVEL LAPSE RATES (AROUND 7-7.5C/KM FROM 850-700MB). THIS
HELPS BOOST HAIL CAPE VALUES TOWARDS 800 J/KG...BUT WITH FREEZING
LEVELS AROUND 12KFT...IT MAY COUNTERACT THE HAIL POTENTIAL. 0-6KM
AND EFFECTIVE SHEAR VALUES ARE MARGINAL FOR THUNDERSTORM
ORGANIZATION (ONLY AROUND 20-25KTS) AND FAIRLY UNIDIRECTIONAL. 09Z
SREF RUN AGREES WITH THAT BASIC IDEA AND ONLY HAS 50 PERCENT PROBS
FOR EFFECTIVE SHEAR OVER 30KTS. BUT WITH THE COLD FRONT...WOULD
EXPECT SOME CLUSTERS OR LINE OF STORMS TO FORM. STORM MOTION AND
MOVEMENT OF THE COLD FRONT WOULD SUPPORT AN EAST TO SOUTHEAST
MOVEMENT OF THE THUNDERSTORMS. FINALLY...THINK THERE WILL BE SOME
WIND THREAT DUE TO DCAPE VALUES PEAKING OVER THE SOUTH CENTRAL WHERE
THERE WILL BE LESS OF AN INFLUENCE OF CLOUDS TO AID
DESTABILIZATION. THUS...HAVE TRENDED SOME LOCATIONS UP TO
SHOWERS/THUNDERSTORMS LIKELY OVER THE CENTRAL AND WEST-CENTRAL IN
THE AFTERNOON. SPC HAS WESTERN/CENTRAL PORTIONS OF THE U.P. IN A
SLIGHT RISK AND THAT SEEMS REASONABLE AT THIS POINT ALTHOUGH THE
LIMITED SHEAR LEAVES SOME CONCERN FOR WIDESPREAD SEVERE WEATHER.
THE WARM AIR AHEAD OF THE COLD FRONT WILL PRODUCE ANOTHER WARM
DAY...ESPECIALLY OVER THE CENTRAL/EAST (HIGHS IN UPPER 80S OR
LOWER 90S). THE WEST MAY BE LIMITED BY MID CLOUDS MOVING IN AHEAD OF
THE COLD FRONT AND HAVE HIGHS IN THE 80S THERE.
AS THE UPPER TROUGH SHIFT EAST ON THURSDAY...HIGH PRESSURE WILL
BUILD OVER THE AREA WHILE AN UPPER RIDGE BUILD OVER THE NORTH
CENTRAL CONUS AND CENTRAL CANADA. WITH THIS HIGH IN PLACE...EXPECT
ANOTHER PERIOD OF DRIER WEATHER INTO THE FIRST PART OF THE WEEKEND.
A SECONDARY SHORTWAVE MOVES THROUGH ON THURSDAY...BUT WITH THE DRY
ATMOSPHERE...DON/T EXPECT MUCH MORE THAN PASSING MID CLOUDS.
TEMPERATURES DURING THE LONG TERM PERIOD WILL BE COOLEST ON
THURSDAY/FRIDAY BEHIND THE COLD FRONT (HIGHS IN THE
70S)...BUT THEN AS THE HIGH SHIFTS EAST SATURDAY...SOUTH-SOUTHWEST
LOW LEVEL FLOW WILL ALLOW TEMPERATURES TO WARM BACK ABOVE NORMAL
FOR THE WEEKEND (HIGHS AROUND 80S...ALTHOUGH THE LATEST ECMWF IS
SHOWING VALUES NEAR 90).
MODELS DIFFER SOMEWHAT FOR SATURDAY INTO MONDAY...DUE TO CONVECTION
FIRING OR NOT FIRING ALONG THE REMNANTS OF THE COLD FRONT
STRETCHING FROM SOUTHERN MINNESOTA THROUGH THE OHIO RIVER VALLEY.
THE ECMWF HAS BEEN SHOWING THIS FRONT SLOWLY PUSHING NORTH AS A
WARM FRONT THROUGH THE WEEKEND...WHICH WOULD GIVE BETTER CHANCES
FOR PRECIPITATION FOR THE END OF THE WEEKEND INTO THE BEGINNING OF
NEXT WEEK. THE GFS ON THE OTHERHAND AS BEEN SHOWING A STRONGER HIGH
LINGERING OVER THE AREA AND KEEPING THE BROAD AREA OF LOW PRESSURE
FOCUSED IN THE DAKOTAS (SIMILAR TO WHAT WE HAVE EXPERIENCED OVER
THE LAST COUPLE OF DAYS). BOTH MODELS HAVE BEEN VARYING ON THEIR
SOLUTIONS OVER THE LAST COUPLE OF DAYS...SO CONFIDENCE IS LIMITED
THIS FAR OUT. THEREFORE...WILL FOLLOW A GENERAL CONSENSUS WITH
CHANCE OR SLIGHT CHANCE POPS FOR THE WEEKEND INTO EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 128 PM EDT MON AUG 19 2013
WITH RELATIVELY DRY LOW-LEVELS PERSISTING...VFR CONDITIONS ARE
EXPECTED THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. A WEAK DISTURBANCE
PASSING OVER THE UPPER LAKES COMBINED WITH BUILDING DAYTIME
INSTABILITY COULD SPARK ISOLD CONVECTION THIS AFTN WHICH MIGHT
AFFECT KIWD/KSAW. HOWEVER...CONFIDENCE IN DEVELOPMENT/LOCATION OF
ANY SHRA/TSRA IS VERY LOW. SO...NO MENTION OF SHRA/TSRA WAS INCLUDED
IN THIS FCST. AS WITH RECENT NIGHTS...INCREASING SW WINDS TONIGHT
ABOVE NOCTURNAL INVERSION WILL APPROACH LLWS CRITERIA.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 422 PM EDT MON AUG 19 2013
OVERALL...EXPECT WINDS LESS THAN 20KT THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. ONE PERIOD OF STRONGER WINDS (GUSTS TO 20-25KT)
MAY OCCUR TUE NIGHT AS PRES GRADIENT TIGHTENS DUE TO APPROACHING
COLD FRONT. THE ARRIVAL OF MORE HUMID AIR TUE/WED MAY RESULT IN SOME
FOG FORMATION OVER THE COOLER LAKE WATERS. HOWEVER...FOG WILL BE
MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS OCCUR OVER THE LAKE. ANY
FOG WILL DISSIPATE WED AFTN/EVENING FOLLOWING A COLD FRONTAL PASSAGE
AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
129 PM EDT MON AUG 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 359 AM EDT MON AUG 19 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A ZONAL FLOW OVER
SRN CANADA TO THE N OF UPR RDG EXTENDING FM THE WRN PLAINS INTO THE
GREAT LKS. THE WX OVER UPR MI IS QUIET EARLY THIS MRNG...WITH
DRY/STABLE AIRMASS DEPICTED ON THE 00Z MPX/GRB RAOBS DOMINATING THE
AREA. THERE ARE 2 SHRTWVS EMBEDDED IN THE ZONAL FLOW THAT ARE OF
CONCERN. THE FIRST OF THESE IS MOVING EWD THRU THE DAKOTAS
AND ARPCHG NW MN...ACCOMPANIED BY SCT SHRA/TS. THE SECOND IS MOVING
THRU NW ONTARIO WITH A CLUSTER OF SHRA/TS NW OF LK NIPIGON...BUT
SOME ISOLD SHRA/TS WITHIN THE COMMA TAIL OF THIS FEATURE EXTEND
FARTHER S INTO THE MN ARROWHEAD UNDER SOME H85-5 QVECTOR CNVGC
ASSOCIATED WITH FAIRLY VIGOROUS H85 THETA E ADVECTION IN ADVANCE OF
AXIS OF HIER H85 DEWPTS UP TO 15C AT ABERDEEN SDAKOTA AND 13C AT
INL. WHILE THE 00Z MPX/GRB RAOBS ARE QUIET DRY/STABLE WITH KINX OF
0/-2 RESPECTIVELY AND PWAT ARND 0.75 INCH /NEAR 75 PCT OF
NORMAL/...THE 00Z INL RAOB IS MORE MOIST AND CONDITIONALLY
UNSTABLE...WITH KINX OF 36 AND PWAT 1.47 INCH /175 PCT OF NORMAL/.
DESPITE THE RATHER IMPRESSIVE MOISTENING...LATEST TRENDS INDICATE
FEW IF ANY LTG STRIKES WITHIN THE CONVECTION.
MAIN FCST CONCERNS IN THE SHORT TERM ARE RELATED TO PCPN CHCS
ASSOCIATED WITH PAIR OF SHRTWVS NOTED ABOVE.
TDAY...SHRTWVS MOVING INTO MN AND THRU ONTARIO ARE PROGGED TO
CONTINUE DRIFTING E THRU THE DAY. AS AXIS OF VIGOROUS H85 THETA E
ADVECTION/H85-5 QVECTOR CNVGC SHIFT E THIS MRNG...EXPECT SOME ISOLD
SHRA TO INVADE THE WRN COUNTIES. BUT MODEL GUIDANCE IN GENERAL SHOWS
THE SHARPER H85-5 QVECTOR CNVGC ASSOCIATED WITH THE ONTARIO SHRTWV
PASSING TO THE N AND MORE VIGOROUS FORCING IN ADVANCE OF THE MN
DISTURBANCE FOCUSING TO THE S BEFORE FADING IN THE AFTN. SO GOING
FCST SHOWING A DIMINISHING TREND IN THE POPS THRU THE MRNG SEEMS ON
TRACK. GIVEN OBSVD LTG STRIKES AND TENDENCY FOR DIMINISHING DYNAMIC
SUPPORT...REMOVED MENTION OF TS THIS MRNG. WHETHER DAYTIME HEATING
/DESTABILIZATION CAN REINVIGORATE/SUSTAIN ANY CONVECTION WL BE THE
CONCERN FOR THE AFTN. IN FACT...THE 00Z REGIONAL GEM AND GFS ARE THE
ONLY MODELS THAT GENERATE ANY PCPN OVER THE CWA THIS AFTN. THE GFS
FCST SDNGS SHOW RATHER UNIMPRESSIVE LAPSE RATES WITH A TENDENCY FOR
A PERSISTENT CAP AND WARMING MID LVL TEMPS IN THE 18Z-24Z TIME FRAME
ASSOCIATED WITH THE FADING DYNAMIC SUPPORT. NAM/GFS MOS POPS ARE
UNDER 10 AT MOST PLACES...BUT OPTED TO RETAIN SCHC POPS TO INCLUDE
TS WITH ARRIVAL OF MOISTER AIR/PWAT UP TO 1.5 INCH AND SFC TEMPS
EXPECTED TO REACH ARND 85 THAT WL LIFT MUCAPE UP TO 800-1000J/KG
AWAY FM THE MODERATING INFLUENCE OF THE LKS.
TNGT...WITH RISING HGTS/DNVA/DEEP QVECTOR DVGC...TNGT WL BE DRY AS
ANY AFTN CONVECTION FIZZLES BEFORE SUNSET UNDER THE MID LVL
WARMING/LOWERING SUN ANGLE. ALTHOUGH SKIES WL TURN MOCLR...STEADY SW
WIND SHOULD ACT TO LIMIT THE DIURNAL TEMP FALL. THE WARMEST MIN
TEMPS ARE MOST LIKELY NEAR LK SUP OVER THE W HALF...WHERE THE PRES
GRADIENT WL BE A BIT TIGHER/H925 WINDS 20-25 KTS AND THIS FLOW WL
DOWNSLOPE.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 359 AM EDT MON AUG 19 2013
STARTING TUE...THE CWA WILL BE BETWEEN A SFC HIGH OVER THE
ATLANTIC/ERN CONUS AND AND SFC TROUGH FROM HUDSON BAY INTO THE NRN
PLAINS STATES. SOME OF THE MODELS ARE HINTING AT SOME PRECIP TUE
AFTERNOON...BUT ANY PRECIP SHOULD BE ISOLATED AT BEST GIVEN THAT
THERE WILL NOT BE MUCH MOISTURE AVAILABLE. BEST CHANCE FOR ISOLATED
SHOWERS AND THUNDERSTORMS WILL BE OVER NCENTRAL UPPER MI WHERE LAKE
BREEZE CONVERGENCE WILL HELP ENCOURAGE CONVECTION ALONG. 850MB TEMPS
AT 18Z TUE WILL BE RIGHT AROUND 17-18C AND WITH MOSTLY SUNNY SKIES
SHOULD BE ABLE TO GET HIGH TEMPS IN THE 80S TO AROUND 90.
MODELS ARE IN BETTER AGREEMENT FOR THAT TROUGH/COLD FRONT TO THE NW
TO DROP ACROSS THE CWA ON WED/WED NIGHT...BUT THERE REMAINS SOME
SUBTLE YET IMPORTANT UNCERTAINTY FOR THE SYSTEM. MAIN QUESTION IS
WITH THE EXACT TIMING OF THE COLD FRONT...WHICH EVEN THOUGH MODELS
AGREE WELL ON...THINK THAT IT WILL NOT BE CERTAIN UNTIL A LATER
TIME. THE TIMING OF FROPA IS IMPORTANT BECAUSE WITH 850MB TEMPS UP
TO 20C...TEMPS MAY BE COLDER THAN WHAT IS IN THE FORECAST /MAINLY
OVER THE W WHERE THE FRONT MAY COME IN EARLIER THAN PREVIOUSLY
INDICATED BY MODELS/. THINK THAT AREAS THAT HAVE NOT BEEN IMPACTED
BY THE FRONT /AND ASSOCIATED PRECIP AND CLOUD COVER/ BY AROUND PEAK
HEATING TIME WILL GET INTO THE LOW 90S /AWAY FROM LAKE MICHIGAN/.
SO...IF THE COLD FRONT COMES IN AS THE MODELS ARE CURRENTLY
INDICATING /INTO WRN UPPER MI BY 18Z WED AND CENTRAL UPPER MI BY 00Z
THU/...PORTIONS OF WRN UPPER MI WOULD SEE HIGH TEMPS POSSIBLY 10
DEGREES COLDER THAN WHAT THE PREVIOUS FORECAST HAD. ON THE FLIP
SIDE...THE FRONT COULD VERY WELL COME IN LATER THAN INDICATED BY
MODELS...MEANING THE PREVIOUS FORECAST MAY BE RIGHT ON. AT THIS
POINT WITH THE UNCERTAINTY...WILL NOT CHANGE TEMPS MUCH FOR WED. THE
OTHER IMPACT WITH FROPA TIMING IS ON CONVECTION...SIGNIFICANT SBCAPE
VALUES OF 1500-2500J/KG SHOULD BE PRESENT IN AIRMASS AHEAD OF COLD
FRONT AROUND PEAK HEATING...SO WHEN THE FRONT MOVES THROUGH WILL
DETERMINE STRENGTH/COVERAGE OF CONVECTION. AT THIS POINT...NOT TOO
EXCITED WITH AREAL EXTENT OF CONVECTION GIVEN THAT MOISTURE WILL BE
SOMEWHAT LIMITED /AT LEAST EARLY ON/. AT THE SAME TIME...THAT DRY
AIR WILL HELP DCAPE VALUES GET UP TO AROUND 1000J/KG AND WITH HIGH
FREEZING LEVEL AROUND 14KFT...MAIN THREAT FROM ANY STRONGER OR
ISOLATED SEVERE STORMS WOULD BE STRONG WINDS.
THURSDAY CERTAINLY LOOKS COOLER AND DRIER AS 850MB TEMPS AT 18Z THU
WILL BE AROUND 13C WITH SFC HIGH PRESSURE MOVING IN FROM THE W. HIGH
TEMPS LOOK TO BE IN THE 70S TO AROUND 80 OVER THE SCENTRAL CWA.
AMPLIFIED UPPER LEVEL RIDGE WILL BE WELL TO THE W OF THE CWA.
MODELS IN MUCH BETTER AGREEMENT FOR FRI WITH HAVING THE SFC HIGH
EXIT TO THE E ON FRI AS THE UPPER RIDGE AXIS MOVES OVERHEAD LATE IN
THE DAY. WITH SLY FLOW NOT KICKING IN AND UPPER RIDGE NOT ARRIVING
UNTIL LATE IN THE DAY OR UNTIL FRI NIGHT...WILL NOT HAVE SUFFICIENT
ADVECTION OF WARMER AIRMASS INTO THE AREA. HIGH TEMPS LOOK SIMILAR
OR A DEGREE OR TWO COOLER THAN THURSDAY...WITH HIGHS PRIMARILY IN
THE 70S /WITH SOME COOLER SPOTS NEAR LAKE SUPERIOR/.
UNCERTAINTY INCREASES CONSIDERABLY FOR SAT AND SUN DUE TO MODEL
DISAGREEMENT AND RUN TO RUN DISCONTINUITY. WILL JUST USE CONSENSUS
OF MODELS FOR THIS PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 128 PM EDT MON AUG 19 2013
WITH RELATIVELY DRY LOW-LEVELS PERSISTING...VFR CONDITIONS ARE
EXPECTED THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. A WEAK DISTURBANCE
PASSING OVER THE UPPER LAKES COMBINED WITH BUILDING DAYTIME
INSTABILITY COULD SPARK ISOLD CONVECTION THIS AFTN WHICH MIGHT
AFFECT KIWD/KSAW. HOWEVER...CONFIDENCE IN DEVELOPMENT/LOCATION OF
ANY SHRA/TSRA IS VERY LOW. SO...NO MENTION OF SHRA/TSRA WAS INCLUDED
IN THIS FCST. AS WITH RECENT NIGHTS...INCREASING SW WINDS TONIGHT
ABOVE NOCTURNAL INVERSION WILL APPROACH LLWS CRITERIA.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 359 AM EDT MON AUG 19 2013
OVERALL...EXPECT WINDS LESS THAN 20 KTS THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. THE ARRIVAL OF MORE HUMID AIR FOR TUE/WED MAY
RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE WATERS.
HOWEVER...FOG WILL BE MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS
OCCUR OVER THE LAKE. ANY FOG WILL DISSIPATE THU FOLLOWING A COLD
FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...ROLFSON
MARINE...KC
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
537 PM CDT MON AUG 19 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 227 PM CDT MON AUG 19 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A SHORTWAVE
TROUGH MOVING EAST OVER EASTERN MINNESOTA EARLY THIS AFTERNOON.
EARLIER SHOWERS AND STORMS OVER NORTHWEST WISCONSIN FIZZLED AND
THINGS REMAIN QUIET DESPITE DECENT MU CAPES OF OVER 1000 J/KG. WILL
LEAVE A SLIGHT CHANCE OF PRECIP FOR THE REST OF THE AFTERNOON OVER
N-C WISCONSIN THOUGH. CLOUD COVER HAS HELD BACK TEMPS
SOMEWHAT...AND ARE ONLY IN THE UPPER 70S ACROSS THE NORTH. LOOKING
FARTHER UPSTREAM...PLENTY OF CLEAR CONDITIONS OVER THE NORTHERN
PLAINS. SMALL PRECIP CHANCES AND TEMPS ARE THE MAIN FORECAST
CONCERNS IN THE SHORT-TERM.
TONIGHT...THE SHORTWAVE TROUGH MOVING OVER THE WESTERN GREAT LAKES
WILL SHEAR APART INTO TWO FEATURES. ONE WAVE WILL CONTINUE TO MOVE
EAST OVER SOUTHERN ONTARIO WHILE THE OTHER DIVES SOUTH ACROSS IOWA.
AS THIS OCCURS...BAND OF MID AND HIGH LEVEL MOISTURE WILL GET
STRETCHED AND DIMINISH...SO ANTICIPATE CLEARING SKIES TO OCCUR THIS
EVENING. THEN THE 850MB MOISTURE PLUME OVER THE CENTRAL AND
NORTHERN PLAINS EDGES EAST AND NOSES INTO WESTERN AND NORTHERN
WISCONSIN LATE TONIGHT. SCT TO WIDELY SCT CLOUDS ARE OCCURRING
WITHIN THIS MOISTURE PLUME AND BUFKIT SOUNDINGS AT RHI INDICATE
SKINNY CAPE UPWARDS OF 1000 J/KG DEVELOPING BY 09Z. WITH MOISTURE
TRANSPORT OCCURRING...CHANCES OF PRECIP ARE NOT NEGLIGIBLE...BUT
PLENTY OF DRY AIR EXISTS ABOVE 850MB AND MID-LEVEL LAPSE RATES ARE
RATHER POOR. WILL CONTINUE WITH THE DRY FORECAST. MUGGIER CONDITIONS
WITH LOWS IN THE UPPER 50S TO LOW 60S.
TUESDAY...LOW LEVEL MOISTURE PLUME WILL STRETCH FROM KANSAS TO
NORTHWEST WISCONSIN...PUSHING DEWPOINTS INTO THE MIDDLE 60S. WITH
TEMPS RISING INTO THE MID TO UPPER 80S...SHOULD SEE A DECENT CU
FIELD DEVELOP OVER CENTRAL AND NORTH-CENTRAL WISCONSIN. DESPITE
MID-LEVEL CAPPING...ML CAPES TOMORROW WILL REACH UPWARDS OF 2K J/KG
WITH NO CIN. NO TRIGGER ALOFT SO WILL GO WITH THE CONSENSUS WHICH
IS A DRY FORECAST.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 227 PM CDT MON AUG 19 2013
FOCUS OF THIS PERIOD OF THE FORECAST WILL BE THE COLD FRONT
PASSAGE WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. THIS COLD FRONT
WILL BE SUPPORTED BY A SHORT WAVE TROUGH DROPPING INTO THE
NORTHERN GREAT LAKES REGION ALONG WITH A RRQ REGION OF THE UPPER
JET. INCREASING MOIST WARM UNSTABLE AIR MASS PRODUCING CAPES FROM
2500 TO 3000 J/KG FOR THE AFTERNOON HOURS AHEAD OF THE FRONT.
GOING HWO WILL CONTINUE TO HIGHLIGHT THE SVR THREAT. HEAT INDEX
NUMBERS ALSO CLIMB INTO THE LOWER 90S AHEAD OF THE FRONT ON
WEDNESDAY.
MEDIUM RANGE MODELS CONSISTENT WITH DRIVING THE FRONT SOUTH ON
THURSDAY FOR DRIER CONDITIONS AND MORE NORMAL TEMPERATURES.
PRECIPITATION TRENDS BECOME A CHALLENGE AGAIN LATER FRIDAY INTO
NEXT MONDAY. RETURN FLOW FRIDAY NIGHT INTO SATURDAY MAY PRODUCE A
PERIOD OF WAA CONVECTION...FOLLOWED BY PERIODS OF CONVECTION ON
THE NORTHERN PERIMETER OF THE BUILDING UPPER RIDGE LATER WEEKEND
INTO NEXT MONDAY. ORIENTATION OF THIS RIDGE WILL PLAY A ROLE WHERE
THE BEST CHANCE OF CONVECTION OCCURS. WITH THE BUILDING RIDGE
AGAIN THIS WEEKEND INTO NEXT WEEK...THE WARM AND MORE HUMID
AIR MASS WILL RETURN. HEAT INDEX NUMBERS LIKELY TO CLIMB BACK INTO
THE LOWER 90S EXCEPT FOR LOCATIONS ACROSS THE NORTH WHWERE
CONVECTION CAN DEVELOP.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 532 PM CDT MON AUG 19 2013
DECOUPLING OVERNIGHT WL ALLOW WINDS TO DIMINISH AND GUSTINESS TO
END. INCREASED MOISTURE COULD RESULT IN SOME MVFR VSBYS BY MORNING
IN FG/HZ. DEEPENING MIXING WL BRING BACK THE GUSTINESS TO THE WIND
AGAIN TOMORROW. INCREASED MOISTURE COULD RESULT IN SOME LOWER-END
VFR CIGS BY EARLY TOMORROW AFTN...ESP IN C/N-C WI. ATM WL
DESTABILIZE SOME AND THERE DOESN/T APPEAR TO BE ANY CINH REMAINING
IN FCST SOUDNINGS. BUT GIVEN THE LACK OF A TRIGGER...EXPECT
CONVECTION TO BE ISOLD AT BEST AND THUS RISK OF GETTING TSRA AT
TAF SITES NOT GREAT ENOUGH TO WARRANT INCLUSION IN TAFS AT THIS
POINT.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
249 PM CDT MON AUG 19 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 249 PM CDT MON AUG 19 2013
MAIN FORECAST CONCERNS ARE ON ANY POTENTIAL PRECIPITATION TONIGHT
AND THEN TEMPERATURES FOR TUESDAY.
CURRENTLY AS OF 19Z...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING
ALONG THE WEST COAST OF BRITISH COLUMBIA...UPPER RIDGING FROM THE
SOUTHWESTERN U.S. INTO THE DAKOTAS...AND A SHORTWAVE TROUGH OVER
CENTRAL MN. THE MAIN IMPACT TO THE FORECAST AREA WITH THE SHORTWAVE
TROUGH HAS BEEN TO SPREAD SOME MID AND HIGH CLOUDS ACROSS. DRY AIR
IN THE MID LEVELS OF THE ATMOSPHERE SEEN ON THE 12Z MPX SOUNDING...
AS WELL AS A CAPPING INVERSION AT 750MB ON THAT SOUNDING...HAS
PREVENTED THE SHORTWAVE FROM PRODUCING PRECIPITATION IN THE FORECAST
AREA. THE CLOUD COVER HAS ALSO HELD BACK TEMPERATURES FROM REACHING
THEIR MAXIMUM POTENTIAL. 16C 850MB TEMP ON THE MPX SOUNDING WAS
ADVECTING EAST INTO THE FORECAST AREA...WHICH NORMALLY WOULD SUPPORT
MID TO EVEN UPPER 80S WITH CLEAR SKIES. HOWEVER...THE CLOUDS HAVE
HELD TEMPS DOWN INTO THE UPPER 70S TO LOW 80S THUS FAR. LOW LEVEL
SOUTHERLY FLOW HAS SLOWLY BEEN BRINGING IN MORE MOISTURE WITH
DEWPOINTS IN THE UPPER 50S TO LOW 60S. TO THE NORTHWEST...A COLD
FRONT STRETCHED FROM CENTRAL MANITOBA INTO WESTERN MONTANA. AHEAD OF
THE FRONT...12Z RAOBS SHOWED EVEN WARMER AIR ACROSS THE NORTHERN
PLAINS...WITH 850MB READINGS OF 20-25C AT BIS...ABR...UNR AND GGW.
700MB TEMPS WERE WARMING AS WELL...BETWEEN 8-13C.
SYNOPTIC OVERVIEW...
THE SHORTWAVE TROUGH OVER CENTRAL MN IS PROGGED TO DROP SOUTH
THROUGH THE FORECAST AREA THIS EVENING...WITH THE EXTENSION OF THE
UPPER RIDGE OVER THE DAKOTAS FOLLOWING IN BEHIND IT FOR THE
OVERNIGHT HOURS INTO TUESDAY.
DETAILS...
GIVEN THE DRY AIRMASS IN PLACE SUB THE MID-CLOUD LAYER AS WELL AS
THE CAPPING...NOT ANTICIPATING ANY PRECIPITATION TO ACCOMPANY THE
SHORTWAVE AS IT DROPS THROUGH THE FORECAST AREA THIS EVENING. WE
SHOULD SEE SOME CLEARING AS WELL...BOTH OF THE MID/HIGH CLOUDS AND
DIURNAL CUMULUS...AS SUBSIDENCE WORKS IN BEHIND THE SHORTWAVE
TROUGH. 850MB MOISTURE TRANSPORT THEN KICKS IN...TRANSPORTING MORE
LOW LEVEL MOISTURE INTO THE AREA. THE 19.12Z NAM/REGIONAL CANADIAN
BOTH DEVELOP A FEW ACCAS TYPE SHOWERS AND THUNDERSTORMS ON THE EDGE
OF THIS MOISTURE TRANSPORT FROM SOUTHEAST MN INTO NORTHWEST WI.
THESE ARE REALLY THE ONLY MODELS SHOWING THIS...AND WITH A BROAD
850MB MOISTURE TRANSPORT PLUME PROGGED COMBINED WITH SUBSIDENCE...
THINK THEY ARE OVERDONE AND KEPT A DRY FORECAST GOING. WORTH KEEPING
AN EYE ON...THOUGH.
THE MORE MOISTURE COMING IN COMBINED WITH DAYTIME HEATING SHOULD
YIELD TO PLENTY OF CUMULUS ON TUESDAY. LITTLE IN THE WAY OF CAPPING
IS PROGGED TOMORROW WITH MLCIN VALUES DROPPING TO 30-40 J/KG IN THE
AFTERNOON...WHILE MLCAPES GROW TO 1500-2500 J/KG. HOWEVER...THERE IS
NO TRIGGER PRESENT TO ALLOW THE RELEASE OF THE INSTABILITY.
THEREFORE...DRY CONDITIONS ARE FORECAST THROUGH TUESDAY.
TEMPERATURES TONIGHT EXPECTED TO BE WARMER...ESPECIALLY OVER THE
NORTHWEST HALF OF THE FORECAST AREA...DUE TO A SOUTHERLY BREEZE AND
HIGHER DEWPOINTS. THE SOUTHERLY BREEZE SHOULD PRECLUDE VALLEY
FOG PRETTY MUCH EVERYWHERE EXCEPT FOR THE WISCONSIN RIVER VALLEY.
850MB AND 925MB TEMPS ARE PROGGED ABOUT 2-3C HIGHER ON TUESDAY
AFTERNOON COMPARED TO THIS AFTERNOON. THESE WARMER TEMPS COMBINED
WITH MORE SUN WILL LEAD TO WARMER CONDITIONS...LIKELY BY 5 OR SO
DEGREES.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 249 PM CDT MON AUG 19 2013
HAZARDS...
HEAT INDICES MAY GET CLOSE TO ADVISORY CRITERIA ON WEDNESDAY AND
AGAIN SUNDAY AND MONDAY. ALSO MONITORING POTENTIAL SEVERE WEATHER
FOR LATE WEDNESDAY.
SYNOPTIC OVERVIEW...
TROUGHING ALONG THE WEST COAST OF BRITISH COLUMBIA IS FORECAST
CONCERN NUMBER 1...WITH MODELS STRUGGLING A BIT ON THE AMPLITUDE OF
THE TROUGH AS IT CROSSES SOUTHERN CANADA THE NEXT COUPLE OF DAYS.
SOME PAST GFS RUNS INDICATED THE TROUGH COULD DIP INTO NORTHERN
MINNESOTA LATE WEDNESDAY...WHEREAS THE ECMWF AS WELL AS THE 19.12Z
GFS KEEP IT TO THE NORTH CROSSING NORTHERN ONTARIO. THIS IS
IMPORTANT AS IT IMPACTS HOW FAR SOUTH DYNAMICAL FORCING WILL REACH
INTO THE FORECAST AREA. ADDITIONALLY...THIS SHORTWAVE TROUGH IS
GOING TO DICTATE THE SPEED OF THE COLD FRONT OVER MONTANA...THE
FORCING ON THE FRONT...AND HOW FAR SOUTH THE FRONT GETS HEADING INTO
THURSDAY AND THURSDAY NIGHT. GOOD MODEL AGREEMENT PERSISTS HEADING
INTO NEXT WEEKEND AS THE SUMMER HEAT RIDGE BUILDS AND STRENGTHENS
OVER THE NATIONS HEARTLAND. VERY LITTLE MOVEMENT OF THIS RIDGE IS
SUGGESTED BY MONDAY.
TUESDAY NIGHT THROUGH THURSDAY...
FOCUS IS ON THE COLD FRONT APPROACHING THE AREA. ALL MODELS ARE
SHOWING AN ELEVATED MIX LAYER...I.E. THE WARMER 850MB AND 700MB AIR
PRESENT CURRENTLY OVER THE NORTHERN PLAINS...ADVECTING INTO THE
FORECAST AREA TUESDAY NIGHT AND WEDNESDAY AHEAD OF THE FRONT. THE
EXACT WARMTH IS ONE FACTOR THAT WILL PLAY INTO WHETHER OR NOT THIS
FRONT CAN INITIATE CONVECTION WEDNESDAY AFTERNOON. ANOTHER FACTOR IS
MOISTURE...WHICH THE 19.12Z GFS AND NAM BOTH APPEAR TO BE OVERDOING
THE SURFACE DEWPOINTS. THEY PROG VALUES IN THE 70-75 RANGE WHILE
MIXING AND THE DRYING SOILS SHOULD RESULT IN READINGS MORE IN THE
MID/UPPER 60S. THESE MIXED LAYER DEWPOINTS RESULT IN MLCIN VALUES OF
30-50 J/KG. A THIRD FACTOR OF CONCERN IS LOW LEVEL CONVERGENCE...
WHICH THE NAM AND GFS BOTH PROG WEAK TO NOTHING PRIOR TO THEIR
CONVECTIVE SCHEMES GOING OFF. THUS...THERE IS PLENTY OF UNCERTAINTY
ON THE EXTENT OF POTENTIAL CONVECTION. IN REALITY...THERE IS A
BETTER SHOT FOR CONVECTION ONCE THE FRONT PASSES...DUE TO THE
DEVELOPMENT OF A POST-FRONTAL LOW TO MID LEVEL FRONTOGENESIS ZONE.
HAVE TAILORED PRECIPITATION CHANCES IN THIS WAY WITH HIGHER VALUES
WEDNESDAY NIGHT. PRECIPITATION CHANCES CONTINUE INTO THURSDAY...
MAINLY SOUTH OF I-90...WHERE THE FRONTOGENESIS ZONE MAY STILL BE
LINGERING. THIS IS ALL DEPENDS ON HOW FAR SOUTH THE FRONT MAKES
IT...THOUGH.
FOR SEVERE WEATHER POTENTIAL...THE 0-6KM SHEAR IS SERIOUSLY LAGGING
THE FRONT. 25 KT IS ABOUT THE HIGHEST AT 00Z AND THATS UP NEAR EAU
CLAIRE. 0-3 KM IS NOT MUCH BETTER WITH SIMILAR VALUES. THUS THINKING
THAT IF THERE IS A SEVERE RISK...MORE LIKELY IT IS UP NORTH OF HWY
10 DURING THE LATE AFTERNOON/EVENING HOURS.
ON THE TEMPERATURE SIDE OF THINGS...925MB READINGS FROM THE
ECMWF/GFS ARE PROGGED TO CLIMB TO 24-26C LATE WEDNESDAY. WITH PLENTY
OF SUN MUCH OF THE DAY AND A SOUTHWEST BREEZE...HIGHS SHOULD TOP OUT
BETWEEN THE UPPER 80S AND MID 90S. DEWPOINTS MIXING DOWN INTO THE
MID TO UPPER 60S WILL HELP TO HOLD HEAT INDICES BELOW ADVISORY
CRITERIA. 925MB TEMPS COOLING TO 20-22C FOR THURSDAY LIKELY TO DROP
TEMPS 5-10 DEGREES FROM WEDNESDAY.
THURSDAY NIGHT THROUGH MONDAY...
INITIAL FOCUS FOR THIS TIME PERIOD IS THE RETURN BACK NORTH OF THE
COLD FRONT...I.E. SWITCHING TO A WARM FRONT...AND IF ANY CONVECTION
CAN FIRE ON THAT. THE 19.00Z ECMWF IS THE MOST BULLISH ON FIRING
CONVECTION FOR THURSDAY NIGHT AND FRIDAY AS THE FRONT LIFTS THROUGH
THE FORECAST AREA. 19.12Z GFS/CANADIAN ARE BOTH DRY.
NEXT CONCERN TURNS TO THE HEAT FOR THE WEEKEND INTO MONDAY AS THE
STRONG SUBTROPICAL RIDGE FORMS OVER NEBRASKA...IOWA...KANSAS AND
MISSOURI. THE BULK OF THE HEAT WITH 850MB TEMPS OF 24C OR HIGHER
LOOKS TO STAY WELL OFF TO THE WEST OVER THE DAKOTAS INTO WESTERN
PORTIONS OF NEBRASKA AND KANSAS. HOWEVER...THEY SHOULD STILL TOP OUT
IN THE 18-22C RANGE FOR SATURDAY THROUGH MONDAY...WITH THE HIGHER
READINGS OF 20-22C LIKELY OCCURRING SUNDAY AND MONDAY. THESE ARE
1.5-2 STANDARD DEVIATIONS ABOVE NORMAL...WHICH WOULD IMPLY CLOSE TO
BUT NOT REACHING OR EXCEEDING RECORD HIGHS. LOW TEMPERATURES COULD
TURN OUT QUITE WARM AS WELL WITH A PERSISTENT SOUTH TO SOUTHWEST
BREEZE. INDICATIONS FROM THE 19.12Z ECMWF THAT THE WELL ABOVE NORMAL
TEMPERATURES COULD STICK AROUND WELL BEYOND MONDAY.
PRECIPITATION CHANCES FOR THE WEEKEND INTO EARLY NEXT WEEK SHOULD
STAY CONFINED MOSTLY NORTH OF THE FORECAST AREA...WHERE THE WARM
FRONT FROM THURSDAY NIGHT/FRIDAY WILL BE LOCATED. THERE ARE
POSSIBILITIES THAT THE FRONT COULD SLIP BACK SOUTH INTO NORTHERN
SECTIONS OF THE FORECAST AREA AT TIMES SUNDAY NIGHT AND
MONDAY...THUS HAVE SOME CHANCES IN FOR THIS PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1220 PM CDT MON AUG 19 2013
SHORT WAVE TROUGH MOVING SLOWLY ACROSS THE UPPER MIDWEST TODAY
CONTINUES TO PRODUCE A HIGH VFR CEILINGS OVER BOTH TAF SITES. RADAR
SUGGESTS SOME SPRINKLES FROM TIME TO TIME ARE POSSIBLE...BUT THIS
HAS BEEN TO THE NORTH. CANNOT TOTALLY RULE THESE OUT THROUGH THE
REMAINDER OF THE AFTERNOON AS BOTH THE 19.12Z NAM AND 19.15Z RAP
SHOW AN INCREASE IN THE LOW LEVEL MOISTURE TRANSPORT. DESPITE THIS
EXPECTED INCREASE IN THE MOISTURE TRANSPORT...FORECAST SOUNDINGS
CONTINUE TO SHOW QUITE A BIT OF DRY AIR IN THE LOW LEVELS SO WOULD
NOT EXPECT ANYTHING MORE THAN SPRINKLES. ONCE THIS WAVE MOVES
PAST...SKIES SHOULD CLEAR OUT THIS EVENING AND REMAIN THAT WAY
INTO TUESDAY MORNING. WITH HIGH PRESSURE REMAINING OVER THE OHIO
RIVER VALLEY AND A COLD FRONT SLOWLY APPROACHING FROM THE
NORTHWEST...ENOUGH OF A GRADIENT TO KEEP THE WINDS UP OVERNIGHT
WHICH SHOULD PRECLUDE THE FORMATION OF ANY VALLEY FOG.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...04
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 227 PM CDT MON AUG 19 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A SHORTWAVE
TROUGH MOVING EAST OVER EASTERN MINNESOTA EARLY THIS AFTERNOON.
EARLIER SHOWERS AND STORMS OVER NORTHWEST WISCONSIN FIZZLED AND
THINGS REMAIN QUIET DESPITE DECENT MU CAPES OF OVER 1000 J/KG. WILL
LEAVE A SLIGHT CHANCE OF PRECIP FOR THE REST OF THE AFTERNOON OVER
N-C WISCONSIN THOUGH. CLOUD COVER HAS HELD BACK TEMPS
SOMEWHAT...AND ARE ONLY IN THE UPPER 70S ACROSS THE NORTH. LOOKING
FARTHER UPSTREAM...PLENTY OF CLEAR CONDITIONS OVER THE NORTHERN
PLAINS. SMALL PRECIP CHANCES AND TEMPS ARE THE MAIN FORECAST
CONCERNS IN THE SHORT-TERM.
TONIGHT...THE SHORTWAVE TROUGH MOVING OVER THE WESTERN GREAT LAKES
WILL SHEAR APART INTO TWO FEATURES. ONE WAVE WILL CONTINUE TO MOVE
EAST OVER SOUTHERN ONTARIO WHILE THE OTHER DIVES SOUTH ACROSS IOWA.
AS THIS OCCURS...BAND OF MID AND HIGH LEVEL MOISTURE WILL GET
STRETCHED AND DIMINISH...SO ANTICIPATE CLEARING SKIES TO OCCUR THIS
EVENING. THEN THE 850MB MOISTURE PLUME OVER THE CENTRAL AND
NORTHERN PLAINS EDGES EAST AND NOSES INTO WESTERN AND NORTHERN
WISCONSIN LATE TONIGHT. SCT TO WIDELY SCT CLOUDS ARE OCCURRING
WITHIN THIS MOISTURE PLUME AND BUFKIT SOUNDINGS AT RHI INDICATE
SKINNY CAPE UPWARDS OF 1000 J/KG DEVELOPING BY 09Z. WITH MOISTURE
TRANSPORT OCCURRING...CHANCES OF PRECIP ARE NOT NEGLIGIBLE...BUT
PLENTY OF DRY AIR EXISTS ABOVE 850MB AND MID-LEVEL LAPSE RATES ARE
RATHER POOR. WILL CONTINUE WITH THE DRY FORECAST. MUGGIER CONDITIONS
WITH LOWS IN THE UPPER 50S TO LOW 60S.
TUESDAY...LOW LEVEL MOISTURE PLUME WILL STRETCH FROM KANSAS TO
NORTHWEST WISCONSIN...PUSHING DEWPOINTS INTO THE MIDDLE 60S. WITH
TEMPS RISING INTO THE MID TO UPPER 80S...SHOULD SEE A DECENT CU
FIELD DEVELOP OVER CENTRAL AND NORTH-CENTRAL WISCONSIN. DESPITE
MID-LEVEL CAPPING...ML CAPES TOMORROW WILL REACH UPWARDS OF 2K J/KG
WITH NO CIN. NO TRIGGER ALOFT SO WILL GO WITH THE CONSENSUS WHICH
IS A DRY FORECAST.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 227 PM CDT MON AUG 19 2013
FOCUS OF THIS PERIOD OF THE FORECAST WILL BE THE COLD FRONT
PASSAGE WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. THIS COLD FRONT
WILL BE SUPPORTED BY A SHORT WAVE TROUGH DROPPING INTO THE
NORTHERN GREAT LAKES REGION ALONG WITH A RRQ REGION OF THE UPPER
JET. INCREASING MOIST WARM UNSTABLE AIR MASS PRODUCING CAPES FROM
2500 TO 3000 J/KG FOR THE AFTERNOON HOURS AHEAD OF THE FRONT.
GOING HWO WILL CONTINUE TO HIGHLIGHT THE SVR THREAT. HEAT INDEX
NUMBERS ALSO CLIMB INTO THE LOWER 90S AHEAD OF THE FRONT ON
WEDNESDAY.
MEDIUM RANGE MODELS CONSISTENT WITH DRIVING THE FRONT SOUTH ON
THURSDAY FOR DRIER CONDITIONS AND MORE NORMAL TEMPERATURES.
PRECIPITATION TRENDS BECOME A CHALLENGE AGAIN LATER FRIDAY INTO
NEXT MONDAY. RETURN FLOW FRIDAY NIGHT INTO SATURDAY MAY PRODUCE A
PERIOD OF WAA CONVECTION...FOLLOWED BY PERIODS OF CONVECTION ON
THE NORTHERN PERIMETER OF THE BUILDING UPPER RIDGE LATER WEEKEND
INTO NEXT MONDAY. ORIENTATION OF THIS RIDGE WILL PLAY A ROLE WHERE
THE BEST CHANCE OF CONVECTION OCCURS. WITH THE BUILDING RIDGE
AGAIN THIS WEEKEND INTO NEXT WEEK...THE WARM AND MORE HUMID
AIR MASS WILL RETURN. HEAT INDEX NUMBERS LIKELY TO CLIMB BACK INTO
THE LOWER 90S EXCEPT FOR LOCATIONS ACROSS THE NORTH WHWERE
CONVECTION CAN DEVELOP.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1202 PM CDT MON AUG 19 2013
MAINLY VFR CONDITIONS ACROSS THE REGION THROUGH THE TAF
PERIOD. WIDELY SCT SHOWERS AND THUNDERSTORMS ARE POSSIBLE THIS
AFTERNOON OVER NORTH-CENTRAL WISCONSIN. COVERAGE IS EXPECTED TO BE
LOW ENOUGH TO LEAVE OUT OF TAFS. PATCHY MVFR VSBYS IN MIST IS
POSSIBLE LATE TONIGHT. MOISTURE INCREASES FROM THE SOUTHERN PLAINS
TOMORROW...WHICH SHOULD LEAD TO BUILDING CLOUDS OVER THE COURSE OF
THE MORNING...MAINLY FOR CENTRAL AND NORTH-CENTRAL WISCONSIN.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1220 PM CDT MON AUG 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 327 AM CDT MON AUG 19 2013
THE MAIN FOCUS FOR TODAY IS ON A MID LEVEL TROUGH THAT WILL COME
THROUGH AND WHETHER IT WILL HAVE ENOUGH LIFT TO OVERCOME THE DRY
LOW LEVEL AIR AND PRODUCE SOME RAIN SHOWERS.
THIS MID LEVEL TROUGH IS CURRENTLY ANALYZED VIA WATER VAPOR IR AND
19.06Z RAP 500MB ANALYSIS FROM SOUTHWESTERN ONTARIO THROUGH
MINNESOTA AND EASTERN NEBRASKA. SOME VERY HIGH BASED RADAR RETURNS
HAVE BEEN SHOWING UP ACROSS EASTERN SOUTH DAKOTA AND WESTERN
MINNESOTA THOUGH THERE HAVE NOT BEEN MANY SIGHTS REPORTING THAT
THE RAIN IS REACHING THE GROUND. THIS IS ALSO IN A BELT OF HIGHER
LOW LEVEL MOISTURE TRANSPORT THAT IS TRAPPED UNDER A 700MB
INVERSION...BUT IS HELPING TO RAISE SURFACE DEW POINTS. THIS IN
TURN HAS CREATED A MORE UNSTABLE AIR MASS FROM THE DAKOTAS UP INTO
NORTHERN MINNESOTA. THE 19.07Z RAP KEEPS MUCH OF THIS MOISTURE
TRANSPORT AND HIGHER INSTABILITY OUT TO THE WEST TODAY...SO THIS
TROUGH WILL BE ENTERING AN ENVIRONMENT THAT IS LESS FAVORABLE TO
SEE THE SHOWERS CONTINUE. CONSIDERED PUTTING IN A MENTION OF
SPRINKLES TODAY IN FOR SOUTHEAST MINNESOTA AND WESTERN TO NORTH
CENTRAL WISCONSIN...BUT HELD OFF FOR THE TIME BEING SINCE
REFLECTIVITIES OUT WEST APPEAR TO BE ON A WEAKENING TREND.
MID TO HIGH LEVEL CLOUD COVER WILL BE FAIRLY WIDESPREAD FOR A
PORTION OF THE DAY WHICH WILL KEEP TEMPERATURES DOWN A LITTLE BIT.
THE 19.00Z NAM/GFS SHOW SOME WARMER 850/925MB AIR MOVING IN THIS
AFTERNOON AS SOME OF THIS CLOUD COVER EXITS. EXPECT THAT WE WILL
WARM UP PRETTY QUICKLY AS THIS OCCURS...BUT PERHAPS NOT AS HIGH AS
PREVIOUSLY ADVERTISED.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 327 AM CDT MON AUG 19 2013
CONDITIONS WILL CONTINUE TO WARM INTO MID WEEK AHEAD OF A COLD
FRONT/TROUGH THAT WILL PROPAGATE INTO THE REGION ON WEDNESDAY.
WEDNESDAY IS EXPECTED TO BE THE WARMEST DAY OF THE WEEK WITH LOW
LEVEL WARM AIR ADVECTION BUMPING 925MB TEMPERATURES UP TO AROUND
26C AND 850MB TEMPERATURES TO 20C. THIS WARM LAYER SHOULD ALSO
HELP TO KEEP THE WARM SECTOR CAPPED OFF UNTIL THE COLD FRONT DROPS
DOWN LATE WEDNESDAY AFTERNOON AND EVENING. THE AIR MASS WILL
BECOME UNSTABLE WITH MODIFIED 19.00Z NAM/GFS SOUNDINGS...MODIFIED
FOR LOWER DEW POINTS IN THE MID/UPPER 60S...SHOWING BETWEEN
1500-2500 J/KG OF 0-3KM MUCAPE ALONG A NARROW CORRIDOR JUST AHEAD
OF THE FRONT. WIND SHEAR LOOKS MARGINAL WITH THE BETTER DEEP SHEAR
IN CENTRAL MINNESOTA/NORTHERN WISCONSIN WHERE 500MB WINDS WILL BE
AROUND 40KTS DUE TO THE MID LEVEL SHORT WAVE TROUGH DROPPING INTO
THE NORTHERN GREAT LAKES. FURTHER SOUTHWEST ALONG THE FRONT CLOSER
TO SOUTHERN MINNESOTA AND NORTHERN IOWA...19.00Z NAM/GFS
SOUNDINGS/HODOGRAPHS DO SHOW SOME DIRECTIONAL/SPEED SHEAR IN THE
LOWEST 2KM WHICH WOULD BE MORE FAVORABLE FOR STRONGER WINDS. BASED
ON THE INSTABILITY AND SHEAR...IT APPEARS THAT LARGE HAIL AND
DAMAGING WINDS STILL APPEAR TO BE THE MAIN THREATS IN THE LATE
AFTERNOON INTO THE EVENING...PARTICULARLY ACROSS SOUTHEAST
MINNESOTA...WESTERN WISCONSIN AND NORTHEAST IOWA.
THE ISSUE THEN CONTINUES TO BE WITH HOW FAR SOUTH WILL THE COLD
FRONT MAKE IT AND THEN HOW FAST DOES IT GET PUSHED BACK TO THE
NORTH AS A WARM FRONT BY THE END OF THE WEEK. THE ECMWF HAS
TRENDED TOWARD WHAT THE GFS/GEM HAVE BEEN ADVERTISING THE PAST FEW
DAYS WITH HAVING THE FRONT DROP SOUTH INTO IOWA/NORTHERN ILLINOIS
BY THURSDAY MORNING...BUT THE 19.00Z ECMWF STILL REMAINS THE
FURTHEST NORTH WITH WHERE IT STALLS OUT. THERE ALSO IS BETTER
CONTINUITY WITH THE NEXT TROUGH TRACKING ACROSS THE NORTHERN
PLAINS ON FRIDAY INTO SATURDAY WHICH IS WHEN THE FRONT COMES BACK
NORTH AS A WARM FRONT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1220 PM CDT MON AUG 19 2013
SHORT WAVE TROUGH MOVING SLOWLY ACROSS THE UPPER MIDWEST TODAY
CONTINUES TO PRODUCE A HIGH VFR CEILINGS OVER BOTH TAF SITES. RADAR
SUGGESTS SOME SPRINKLES FROM TIME TO TIME ARE POSSIBLE...BUT THIS
HAS BEEN TO THE NORTH. CANNOT TOTALLY RULE THESE OUT THROUGH THE
REMAINDER OF THE AFTERNOON AS BOTH THE 19.12Z NAM AND 19.15Z RAP
SHOW AN INCREASE IN THE LOW LEVEL MOISTURE TRANSPORT. DESPITE THIS
EXPECTED INCREASE IN THE MOISTURE TRANSPORT...FORECAST SOUNDINGS
CONTINUE TO SHOW QUITE A BIT OF DRY AIR IN THE LOW LEVELS SO WOULD
NOT EXPECT ANYTHING MORE THAN SPRINKLES. ONCE THIS WAVE MOVES
PAST...SKIES SHOULD CLEAR OUT THIS EVENING AND REMAIN THAT WAY
INTO TUESDAY MORNING. WITH HIGH PRESSURE REMAINING OVER THE OHIO
RIVER VALLEY AND A COLD FRONT SLOWLY APPROACHING FROM THE
NORTHWEST...ENOUGH OF A GRADIENT TO KEEP THE WINDS UP OVERNIGHT
WHICH SHOULD PRECLUDE THE FORMATION OF ANY VALLEY FOG.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...04