Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/18/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1030 AM MDT FRI AUG 16 2013
.UPDATE...QUIET DAY TODAY AS AN UPPER LEVEL RIDGE BUILDS OVER THE
REGION. LOW CLOUDS CREPT INTO THE NORTHEAST CORNER OF COLORADO
OVERNIGHT. THEY HAVE BEEN SLOW TO BURN OFF AND WILL LINGER THROUGH
THE REST OF THE MORNING. DROPPED TEMPERATURES A FEW DEGREES OVER
THE NORTHEAST CORNER WHERE THE CLOUDS ARE.
CUMULUS CLOUDS ARE JUST STARTING TO FORM OVER THE MOUNTAINS. MAY
BE JUST ENOUGH MOISTURE AND INSTABILITY FOR A FEW STORMS OVER
HIGHER TERRAIN. PRECIPITABLE WATER VALUES ARE LESS THAN A HALF
INCH ALONG THE FRONT RANGE...THIS SHOULD KEEP STORMS CONFINED TO
THE HIGHER TERRAIN.
&&
.AVIATION...MID AND HIGH CLOUDS WILL INCREASE THIS AFTERNOON AS
CONVECTIVE CLOUDS SPREAD FROM THE HIGHER TERRAIN TO THE FRONT
RANGE. MAY SEE A FEW STORMS OVER THE HIGHER TERRAIN...BUT THE
AIRMASS WILL BE TOO DRY FOR STORMS OVER THE DENVER AREA. WINDS
WILL BE ON THE LIGHT SIDES THROUGH THE NEXT 24 HOURS.
&&
.PREV DISCUSSION... /ISSUED 315 AM MDT FRI AUG 16 2013/
SHORT TERM...SOME STRATUS AND FOG HAS DEVELOPED EARLY THIS
MORNING OVER THE FAR NERN PLAINS AND MAY EVENTUALLY SPREAD FURTHER
WEST INTO MORGAN AND PARTS OF WELD COUNTY BY 12Z. NEITHER THE RAP
OR HRRR SHOW THIS STRATUS/FOG MOVING INTO THE URBAN CORRIDOR AT
THIS POINT SO WILL KEEP IT EAST OF THE FRONT RANGE.
OTHERWISE AN UPPER RIDGE WILL BUILD OVER WRN COLORADO WITH MAINLY
DRY NNW FLOW ALOFT ACROSS THE AREA. HOWEVER THERE STILL COULD BE
SOME ISOLD HIGHER BASED STORMS OVER THE HIGHER FOOTHILLS...MTNS
AND OVER THE PALMER DIVIDE FM MID AFTN THRU THE EARLY EVENING
HOURS. HIGHS THIS AFTN WILL BE A FEW DEGREES WARMER THAN FRIDAY IN
MOST LOCATIONS AS 850-700 MB TEMPS RISE A COUPLE OF DEGREES.
LONG TERM...STRONG...HIGH AMPLITUDE UPPER RIDGE OVER THE DESERT
SOUTHWEST/EASTERN GREAT BASIN/ROCKY MOUNTAIN/WESTERN GREAT PLAINS
REGIONS DOES NOT APPEAR TO BE GOING ANYWHERE TOO SOON ACCORDING TO
THE DETERMINISTIC MODELS AND THEIR ENSEMBLE MEMBERS. THE 500 MB
RIDGE APPEARS TO MEANDER BACK AND FORTH/EAST-WEST/ DURING THE
PERIOD...WHICH CAUSES SUBTLE DAY-TO-DAY SHIFTS IN THE AXIS OF
MONSOONAL MOISTURE PLUME CONNECTED TO THE LOWER DESERTS OF ARIZONA
AND NEW MEXICO. MODELS DIFFER SOME WITH ITS POSITION AND ITS
STRENGTH...BUT OVERALL...THIS CONVEYOR BELT OF SUBTROPICAL
MOISTURE APPEARS TO REMAIN LARGELY ALONG AND WEST OF THE
CONTINENTAL DIVIDE THROUGH THE MIDDLE OF NEXT WEEK. RAIN/T-STORM
CHANCES WILL BE AT THEIR LOWEST THIS WEEKEND FOR NORTH CENTRAL
AND NORTHEAST COLORADO...WITH TEMPERATURES LIKELY TO BE THEIR
WARMEST. NOT SURE WE/LL SEE THE NEAR RECORD HIGH TEMPS ADVERTISED
BY THE GFS...PROBABLY MORE LIKE THOSE OFFERED BY THE ECMWF...BUT
STILL 1-3C ABOVE THE AVERAGE FOR THE DATE. NEXT WEEK...MODELS
INDICATE SLIGHT COOLING...WITH TEMPERATURES RETURNING TO NEAR
AVERAGE...ALONG WITH A SLIGHTLY BETTER CHANCE OF THE AFTERNOON/
EVENING T-STORMS...MAINLY FOR THE MTNS AND HIGH FOOTHILLS. AT THIS
TIME...T-STORMS WITHIN THE CWFA ARE NOT EXPECTED TO PRODUCE HEAVY
RAIN LIKE THOSE OF THE PAST COUPLE OF WEEKS DUE LARGELY TO LOWER
SPECIFIC HUMIDITY AND PRECIPITABLE WATER VALUES. PORTIONS OF
NORTHEAST/EAST CENTRAL COLORADO MAY NOT SEE ANY PRECIP AT ALL
DURING THIS PERIOD.
AVIATION...WINDS WERE DRAINAGE EARLY THIS MORNING AS A WK DENVER
CYCLONE IS WEST OF DIA. BOTH THE RAP AND HRRR SHOW SOME STRATUS
DEVELOPING OVER CNTRL WELD COUNTY BY 12Z HOWEVER NEITHER MODEL
SHOWS IT AFFECTING THE AIRPORT AS WINDS STAY SSW. BY LATE MORNING
THE WK CYCLONE IS FCST TO MOVE SE OF THE AIRPORT WITH WINDS
BECOMING NELY BY 18Z AND CONTINUING THRU THE AFTN HOURS. NO TSTMS
ARE EXPECTED THIS AFTN AS ISOLD ACTIVITY SHOULD STAY OVER THE
HIGHER TERRAIN. FOR THIS EVENING WINDS SHOULD TRANSITION BACK TO
DRAINAGE BY 06Z.
HYDROLOGY...ISOLD HIGH BASED STORMS MAY DEVELOP BY 20Z IN THE
FOOTHILLS HOWEVER THEY WILL ONLY PRODUCE GUSTY WINDS AND LIGHT
RAINFALL.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RJK
LONG TERM....BAKER
AVIATION...MEIER
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
315 AM MDT FRI AUG 16 2013
.SHORT TERM...SOME STRATUS AND FOG HAS DEVELOPED EARLY THIS
MORNING OVER THE FAR NERN PLAINS AND MAY EVENTUALLY SPREAD FURTHER
WEST INTO MORGAN AND PARTS OF WELD COUNTY BY 12Z. NEITHER THE RAP
OR HRRR SHOW THIS STRATUS/FOG MOVING INTO THE URBAN CORRIDOR AT
THIS POINT SO WILL KEEP IT EAST OF THE FRONT RANGE.
OTHERWISE AN UPPER RIDGE WILL BUILD OVER WRN COLORADO WITH MAINLY
DRY NNW FLOW ALOFT ACROSS THE AREA. HOWEVER THERE STILL COULD BE
SOME ISOLD HIGHER BASED STORMS OVER THE HIGHER FOOTHILLS...MTNS
AND OVER THE PALMER DIVIDE FM MID AFTN THRU THE EARLY EVENING
HOURS. HIGHS THIS AFTN WILL BE A FEW DEGREES WARMER THAN FRIDAY IN
MOST LOCATIONS AS 850-700 MB TEMPS RISE A COUPLE OF DEGREES.
.LONG TERM...STRONG...HIGH AMPLITUDE UPPER RIDGE OVER THE DESERT
SOUTHWEST/EASTERN GREAT BASIN/ROCKY MOUNTAIN/WESTERN GREAT PLAINS
REGIONS DOES NOT APPEAR TO BE GOING ANYWHERE TOO SOON ACCORDING TO
THE DETERMINISTIC MODELS AND THEIR ENSEMBLE MEMBERS. THE 500 MB
RIDGE APPEARS TO MEANDER BACK AND FORTH/EAST-WEST/ DURING THE
PERIOD...WHICH CAUSES SUBTLE DAY-TO-DAY SHIFTS IN THE AXIS OF
MONSOONAL MOISTURE PLUME CONNECTED TO THE LOWER DESERTS OF ARIZONA
AND NEW MEXICO. MODELS DIFFER SOME WITH ITS POSITION AND ITS
STRENGTH...BUT OVERALL...THIS CONVEYOR BELT OF SUBTROPICAL
MOISTURE APPEARS TO REMAIN LARGELY ALONG AND WEST OF THE
CONTINENTAL DIVIDE THROUGH THE MIDDLE OF NEXT WEEK. RAIN/T-STORM
CHANCES WILL BE AT THEIR LOWEST THIS WEEKEND FOR NORTH CENTRAL
AND NORTHEAST COLORADO...WITH TEMPERATURES LIKELY TO BE THEIR
WARMEST. NOT SURE WE/LL SEE THE NEAR RECORD HIGH TEMPS ADVERTISED
BY THE GFS...PROBABLY MORE LIKE THOSE OFFERED BY THE ECMWF...BUT
STILL 1-3C ABOVE THE AVERAGE FOR THE DATE. NEXT WEEK...MODELS
INDICATE SLIGHT COOLING...WITH TEMPERATURES RETURNING TO NEAR
AVERAGE...ALONG WITH A SLIGHTLY BETTER CHANCE OF THE AFTERNOON/
EVENING T-STORMS...MAINLY FOR THE MTNS AND HIGH FOOTHILLS. AT THIS
TIME...T-STORMS WITHIN THE CWFA ARE NOT EXPECTED TO PRODUCE HEAVY
RAIN LIKE THOSE OF THE PAST COUPLE OF WEEKS DUE LARGELY TO LOWER
SPECIFIC HUMIDITY AND PRECIPITABLE WATER VALUES. PORTIONS OF
NORTHEAST/EAST CENTRAL COLORADO MAY NOT SEE ANY PRECIP AT ALL
DURING THIS PERIOD.
&&
.AVIATION...WINDS WERE DRAINAGE EARLY THIS MORNING AS A WK DENVER
CYCLONE IS WEST OF DIA. BOTH THE RAP AND HRRR SHOW SOME STRATUS
DEVELOPING OVER CNTRL WELD COUNTY BY 12Z HOWEVER NEITHER MODEL
SHOWS IT AFFECTING THE AIRPORT AS WINDS STAY SSW. BY LATE MORNING
THE WK CYCLONE IS FCST TO MOVE SE OF THE AIRPORT WITH WINDS
BECOMING NELY BY 18Z AND CONTINUING THRU THE AFTN HOURS. NO TSTMS
ARE EXPECTED THIS AFTN AS ISOLD ACTIVITY SHOULD STAY OVER THE
HIGHER TERRAIN. FOR THIS EVENING WINDS SHOULD TRANSITION BACK TO
DRAINAGE BY 06Z.
&&
.HYDROLOGY...ISOLD HIGH BASED STORMS MAY DEVELOP BY 20Z IN THE
FOOTHILLS HOWEVER THEY WILL ONLY PRODUCE GUSTY WINDS AND LIGHT
RAINFALL.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....BAKER
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS MIAMI FL
1052 AM EDT FRI AUG 16 2013
.UPDATE...
GENERALLY EAST TO EAST-SOUTHEASTERLY WINDS SHOULD PREVAIL ACROSS
THE AREA THROUGH THE AFTERNOON WITH THE EXCEPTION OF THE GULF
COAST WHERE A GULF BREEZE SHOULD DEVELOP LATER THIS AFTERNOON.
LATEST HRRR KEEPS MOST OF THE AFTERNOON SHOWERS AND THUNDERSTORMS
ACROSS THE INTERIOR. TWEAKED POPS FOR THE LATE MORNING AND EARLY
AFTERNOON HOURS...OTHERWISE ONGOING FORECAST IS ON TRACK.
&&
.PREV DISCUSSION... /ISSUED 721 AM EDT FRI AUG 16 2013/
AVIATION...
DEEP LAYERED MOISTURE CONTINUES TO LINGER ACROSS THE REGION.
ALTHOUGH THERE IS MID TO UPPER LEVEL CLOUDINESS ACROSS THE
REGION...THERE SHOULD BE SUFFICIENT CLEARING FOR DAY TIME HEATING TO
INITIATE CONVECTION ALONG WITH CONVECTION ASSOCIATED WITH THE EAST
AND WEST COAST SEA BREEZES. THE LOW LEVEL WIND PROFILE COULD BE
FAVORABLE FOR CONVECTION ALONG THE EAST COAST. FOR THE EAST COAST
TAF SITES VCTS WAS ASSIGNED IN THE 17Z TO 18Z TIME FRAME AND 17Z FOR
TERMINAL KAPF. THERE COULD BE SUB-VFR CONDITIONS AND BRIEF PERIODS
OF IFR CONDITIONS WITH THE OCCURRENCE OF SHOWERS/THUNDERSTORMS.
PREV DISCUSSION... /ISSUED 400 AM EDT FRI AUG 16 2013/
SYNOPSIS...
A STATIONARY FRONT WILL REMAIN OVER THE FLORIDA PANHANDLE THROUGH
THE WEEKEND. HIGH PRESSURE BUILDS IN EARLY NEXT WEEK. SCATTERED
AFTERNOON AND EVENING THUNDERSTORMS ARE EXPECTED TODAY THROUGH
MUCH OF NEXT WEEK...WITH GREATEST COVERAGE OVER THE INTERIOR.
SHORT TERM /TODAY THROUGH SUNDAY/...
TWO CLUSTERED OF THUNDERSTORMS BEING MONITORED EARLY THIS
MORNING...OTHERWISE SOUTH FLORIDA HAS REMAINED DRY OVERNIGHT. ONE
IS IMPACTED WATERS OFFSHORE PALM BEACH COUNTY...AND THIS ACTIVITY
IS MOVING NORTHEAST OUT OF THE CWA WHILE WEAKENING. SECOND IS
IMPRESSIVE CONVECTIVE COMPLEX JUST WEST OF GULF WATERS. THESE
FEATURE IS DEPICTED BY MESO-SCALE AND REGIONAL GUIDANCE TO
CONTINUE NORTHWARD AND NOT IMPACT OUR WATERS...BUT THERE IS THE
RISK THAT OUTFLOW FROM IT COULD INITIATE CONVECTION CLOSER TO THE
GULF COAST THIS MORNING. POPS RAISED A BIT ABOVE MODEL CONSENSUS
IN THIS AREA ACCORDINGLY.
WEATHER PATTERN IN PLACE OVER SOUTH FLORIDA THIS MORNING WILL
CHANGE LITTLE THROUGH SUNDAY. PENINSULA RESIDES ON WESTERN
PERIPHERY OF BERMUDA RIDGE...CAUSING SOUTHEASTERLY FLOW AND
MOISTURE ADVECTION FROM THE CARIBBEAN. THIS MOISTURE IS BEING
PULLED INTO AN AREA OF DISTURBED WEATHER NEAR THE YUCATAN
PENINSULA AND ALSO NORTHWARD THROUGH THE PENINSULA TO A STATIONARY
FRONT OVER THE FLORIDA PANHANDLE. OVERALL...CONVECTION WILL
CONCENTRATE NEAR THESE TO CONVERGENCE FEATURES...WITH ONLY
SCATTERED DISORGANIZED CONVECTION EXPECTED OVER SOUTH FLORIDA.
ANTICYCLONIC FLOW CENTERED NEAR SOUTHEAST FLORIDA COAST IS EVIDENT
ON REGIONAL RADAR MOSAIC AND IR SATELLITE LOOPS...THUS AT LEAST
SUBSIDENCE LITTLE OCCUR. THIS SHOULD SUPPRESS CONVECTION SOME
TODAY...ESPECIALLY EASTERN/SOUTHERN ZONES. HIGH CHANCE POPS
CONFINED TO NORTHERN INTERIOR. SIMILAR CONVECTIVE COVERAGE IS
EXPECTED SATURDAY AND SUNDAY...WITH NEAR NORMAL TEMPERATURES.
PWATS REMAIN HIGHER THAN NORMAL...JUST ABOVE 2 INCHES...SO HIGH
RAINFALL RATES ARE LIKELY IN THUNDERSTORMS TODAY. THUS...LOCALLY
HEAVY RAINFALL IS POSSIBLE...THOUGH EXPECTED COVERAGE DOESNT
WARNING HWO HIGHLIGHT.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
FRONT/TROUGH OVER NORTHERN FLORIDA DIMINISHES EARLY NEXT
WEEK...AND DEEP-LYR RIDGE BECOMES MORE DOMINANT IN SOUTH FLORIDA.
FLOW WILL BECOME MORE EASTERLY...FOCUSING DIURNAL CONVECTION
CLOSER TO THE GULF COAST. ECMWF/GFS FORECAST FAIRLY DRY AIR MASS
ADVECTING INTO THE REGION MONDAY/TUESDAY...SO POPS REDUCES
SLIGHTLY THESE DAYS. OTHERWISE...TEMPERATURES ARE EXPECTED TO
REMAIN AVERAGE FOR LATE AUGUST WITH NEAR/JUST BELOW
CLIMATOLOGICAL NORMAL POPS.
MARINE...
MODEST ONSHORE FLOW TODAY AND FORECAST SOUNDINGS SUGGEST LOW-LEVELS
ARE SOMEWHAT FAVORABLE FOR WATERSPOUTS...SO THESE WILL BE
MENTIONED IN HWO. ISOLATED TO SCATTERED THUNDERSTORM COVERAGE IS
EXPECTED THROUGH THE WEEKEND. HIGH PRESSURE CENTERED NORTHEAST OF
FLORIDA WILL AIDE IN SOUTHEASTERLY SURFACE FLOW FOR THE NEXT
SEVERAL DAYS. SPEEDS SHOULD REMAIN AOB 15 KTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 90 78 89 77 / 50 30 20 20
FORT LAUDERDALE 89 80 90 79 / 40 20 20 20
MIAMI 90 79 91 78 / 40 20 20 20
NAPLES 91 77 91 77 / 40 20 40 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...10/CD
AVIATION/RADAR...13/SI
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
500 AM EDT FRI AUG 16 2013
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWING AND UPPER LEVEL PATTERN
THAT IS AMPLIFYING INTO THE EASTERN HALF OF THE CONUS. LONGWAVE
TROUGHING IS DIGGING SOUTHWARD TOWARD THE NORTHERN GULF COAST TO OUR
NORTHWEST WHILE WEAK NE TO SW ELONGATED RIDGING HOLDS OVER THE
CENTRAL AND SOUTHERN FL PENINSULA. ABUNDANT COLUMN MOISTURE IS IN
PLACE BETWEEN THESE 2 FEATURES WITH PW OVER 2" WIDESPREAD ACROSS THE
REGION. CLOSER TO THE SURFACE WE FIND A WEAK VERSION OF THE
SUBTROPICAL RIDGE AXIS ALIGNED OVER THE SOUTHERN HALF OF THE
PENINSULA...SUPPRESSED SOUTHWARD BY A SURFACE TROUGH ELONGATED EAST
TO WEST NEAR THE I-10 CORRIDOR.
REGIONAL RADARS SHOW 2 SEPARATE AREAS OF EXPANDING SHOWER ACTIVITY.
THE FIRST IS OVER THE NATURE COAST TO THE NORTH OF PASCO COUNTY IN
CLOSER PROXIMITY TO THE FOCUS ALONG THE SURFACE TROUGH. THE OTHER IS
A BROAD AREA OF SHOWERS AND STORMS MOVING NORTH OUT OF THE SE GULF
INTO OUR COASTAL WATERS. THIS FEATURE IS NOT BEING HANDLED WELL BY
ANY NUMERICAL GUIDANCE SOLUTION THIS MORNING...AND IS THE FIRST
SIGNS OF WHAT WILL LIKELY BE A DIFFICULT FORECAST TO PUT MUCH DETAIL
INTO FOR ABOUT THE NEXT 48 HOURS. WILL DO MY BEST TO EXPLAIN THE
CURRENT FORECAST PHILOSOPHY BELOW.
&&
.SHORT TERM (TODAY THROUGH SUNDAY)...
TODAY...AS MENTIONED ABOVE...A RATHER CHAOTIC UPPER LEVEL PATTERN
OVER THE SE CONUS/GULF OF MEXICO WILL MAKE THE FORECAST MORE
DIFFICULT THAN NORMAL TO PIN DOWN A LOT OF TEMPORAL DETAILS IN TERMS
OF JUST WHEN AND WHERE THE BEST RAINFALL CHANCES WILL BE. CERTAINLY
WOULD APPEAR THAT THE HIGHEST RAIN CHANCES AND SPATIAL COVERAGE OF
SHOWERS/STORMS THROUGH THE DAY WOULD EXIST OVER OUR NORTHERN NATURE
COAST ZONES WHO WILL CONTINUE TO EXIST IN CLOSEST PROXIMITY TO THE
LOW LEVEL FOCUS OF THE SURFACE TROUGH...AND ALSO INCREASING
PROXIMITY TO THE SYNOPTIC SUPPORT ON THE EASTERN EDGE OF THE DIGGING
UPPER TROUGH ALONG THE NORTHERN GULF COAST. THE REST OF THE REGION
WILL SEE AT LEAST CHANCE POPS THROUGH THE DAY DUE SIMPLY TO THE
EXTENT OF COLUMN MOISTURE THAT IS PLACE. THIS MUCH MOISTURE COMBINED
WITH EVEN A LIMITED AMOUNT OF DIURNAL HEATING THROUGH ABUNDANT
CLOUDS SHOULD BE ENOUGH TO BUBBLE UP A SCATTERING OF CONVECTION.
TONIGHT INTO SATURDAY...THE COMBINATION OF THE UPPER LEVEL SUPPORT
OF THE TROUGH AND THE NORTHWARD MOVEMENT OF THE TROPICAL DISTURBANCE
DOWN TOWARD THE YUCATAN PENINSULA IS FORECAST BY JUST ABOUT ALL THE
RELIABLE NUMERICAL GUIDANCE MODELS TO RESULT IN A ZONE OF HEAVY
RAINFALL POTENTIAL FROM THE CENTRAL GULF OF MEXICO NORTH AND
NORTHEAST INTO THE FL PANHANDLE/SOUTHERN GA. AT THIS POINT...IT
APPEARS AS THOUGH OUR FORECAST AREA WILL SEE JUST ENOUGH INFLUENCE
FROM THE UPPER RIDGE TO HOLD THIS BAND GENERALLY OFF TO OUR NORTH
AND NORTHWEST. LEVY/CITRUS WILL BE THE COUNTIES THAT ARE OF LEAST
CONFIDENCE...BUT FOR NOW IT APPEARS THAT EVEN THESE ZONES WILL
ESCAPE THE HEAVIEST AND WIDESPREAD RAINFALL POTENTIAL. THAT BEING
SAID...THE RIDGE OVERHEAD IS CERTAINLY NOT STRONG ENOUGH TO HOLD
BACK THE MORE TYPICAL DIURNAL SEA-BREEZE TYPE CONVECTION. A LIGHT
EAST TO SOUTHEAST FLOW PATTERN WILL FAVOR AFTERNOON/EVENING
CONVECTION ALONG THE FLORIDA WEST COAST AND THIS WILL BE AIDED BY A
FAVORABLE COLUMN MOISTURE PROFILE SUPPORTIVE OF DEEP CONVECTION.
THEREFORE HIGH END CHANCE TO LIKELY POPS WILL EXIST ALONG THE I-75
CORRIDOR DURING THE SECOND HALF OF SATURDAY...BUT TEMPORAL DURATION
OF THE RAINFALL WILL BE MORE TYPICAL OF SUMMER AS OPPOSED TO WHAT
WILL BE OCCURRING TO OUR NW.
FINALLY FOR SUNDAY WE WILL FIND THE UPPER LEVEL PATTERN
DE-AMPLIFYING AND A RETURN TO A MORE CLIMATOLOGICAL ATMOSPHERIC
COLUMN AND FORECAST. MUCH OF THE MORNING SHOULD BE ON THE QUIET SIDE
GIVING WAY TO AN ACTIVE AFTERNOON OR SHOWERS AND STORMS...BUT
NOTHING UNUSUAL FOR THE MIDDLE OF AUGUST.
&&
.LONG TERM (MONDAY THROUGH NEXT THURSDAY)...
AN U/L RIDGE OVER THE WESTERN ATLANTIC WILL EXTEND ACROSS FLORIDA
MONDAY AND WILL WEAKEN SLIGHTLY ON TUESDAY. A STRONG U/L RIDGE OVER
THE SOUTHERN PLAINS WEDNESDAY WILL BEGIN TO BUILD EAST AND WILL
STRENGTHEN THE RIDGE OVER FLORIDA LATE IN THE WEEK. THIS WILL ALLOW
TEMPERATURES TO RUN A FEW DEGREES ABOVE NORMAL EACH DAY THROUGH THE
EXTENDED PERIOD. SURFACE HIGH PRESSURE ALONG THE MID ATLANTIC COAST
MONDAY WILL CREATE EASTERLY FLOW BOUNDARY LAYER FLOW ACROSS THE
PENINSULA WHICH WILL ENHANCE CONVERGENCE ALONG THE WEST COAST SEA
BREEZE BOUNDARY...WITH SCATTERED AFTERNOON THUNDERSTORMS ACROSS THE
FORECAST AREA...AND NUMEROUS THUNDERSTORMS ALONG THE COASTAL
COUNTIES FROM THE TAMPA BAY AREA SOUTH TO FORT MYERS. SLIGHTLY
DRIER AIR ALOFT WILL ADVECT OVER WEST CENTRAL FLORIDA FROM THE EAST
ON TUESDAY WHICH WILL DECREASE AREAL COVERAGE OF THUNDERSTORMS...BUT
EASTERLY FLOW WILL PERSIST WHICH WILL AGAIN ENHANCE THUNDERSTORM
ACTIVITY ALONG THE WEST COAST SEA BREEZE OVER THE COASTAL COUNTIES
DURING THE MID TO LATE AFTERNOON. DEEP LAYER MOISTURE WILL INCREASE
ON WEDNESDAY WITH CONTINUED EASTERLY BOUNDARY LAYER FLOW WITH
SCATTERED TO NUMEROUS AFTERNOON THUNDERSTORMS WITH HIGHEST POPS
ALONG THE COASTAL COUNTIES. PRESSURE GRADIENT WILL RELAX ON
THURSDAY WHICH WILL ALLOW THE WEST COAST SEA BREEZE BOUNDARY TO PUSH
FURTHER INLAND WITH SCATTERED AFTERNOON THUNDERSTORMS ACROSS ALL OF
WEST CENTRAL AND SOUTHWEST FLORIDA. AN ISOLATED PULSE SEVERE
THUNDERSTORM ARE POSSIBLE EACH AFTERNOON...HOWEVER THE MAIN THREAT
FROM STORMS WILL BE LOCALLY HEAVY RAIN...FREQUENT CLOUD TO GROUND
LIGHTNING...AND WIND GUSTS OF 35 TO 45 MPH.
&&
.AVIATION...
SCT LCL BKN 020-025 DEVELOPING AROUND SUNRISE THIS MORNING LIFTING
TO 030-035 THIS AFTERNOON. SHOWERS AND THUNDERSTORMS VCNTY ALL
TERMINALS...WITH GREATEST AREAL COVERAGE THIS AFTERNOON...WITH LCL
MVFR CIGS AND IFR VSBYS.
&&
.MARINE...
THE EASTERN GULF OF MEXICO WILL RESIDE BETWEEN THE SUBTROPICAL
SURFACE RIDGE TO OUR EAST...AND A BROAD AREA OF SURFACE TROUGHING TO
OUR WEST. JUST HOW STRONG OUR LOCAL GRADIENT AND WINDS END UP BY
SATURDAY WILL DEPENDING ON THE STRENGTH OF THIS SURFACE TROUGH.
CURRENTLY NOT EXPECTING WINDS OR SEAS TO REACH HEADLINE
CRITERIA...ESPECIALLY OVER THE NEAR SHORE WATERS. LATER IN THE
WEEKEND AND INTO THE EARLY PORTION OF NEXT WEEK...THE SURFACE RIDGE
WILL LIFT WELL NORTH OF THE REGION PROVIDING A MORE CONSISTENT
EASTERLY FLOW ACROSS THE FORECAST WATERS.
&&
.FIRE WEATHER...
ABUNDANT TROPICAL MOISTURE WILL OVERSPREAD THE REGION THROUGH THE
WEEKEND AND KEEP RELATIVE HUMIDITY VALUES WELL ABOVE CRITICAL
LEVELS. NO SIGNIFICANT FIRE WEATHER CONCERNS ARE CURRENTLY
ANTICIPATED.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 89 78 93 79 / 50 30 50 30
FMY 92 78 93 77 / 40 30 60 30
GIF 91 75 94 74 / 60 30 50 30
SRQ 90 78 92 76 / 40 30 50 30
BKV 89 74 92 74 / 50 40 60 30
SPG 90 80 93 80 / 50 30 50 30
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...OGLESBY
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
1010 PM EDT SAT AUG 17 2013
.UPDATE...
HAVE TWEAKED THE POPS THROUGH 06Z BASED ON RADAR. SINCE HEAVY RAIN
HAS MOVED EAST OF THE CWA FOR THE TIME BEING...HAVE REMOVED HEAVY
RAIN WORDING FOR THE EVENING. NOT SURE HOW RAIN WILL DEVELOP AFTER
06Z SO HAVE MADE NO CHANGES FOR THE 06Z TO 12Z GRIDS. WILL LET FLOOD
WATCH GO ON UNTIL EXPIRATION AT 12Z. FLASH FLOOD GUIDANCE IS SO LOW
IN THE WATCH AREA THAT ANOTHER ROUND OF SHOWERS COULD CAUSE
PROBLEMS.
41
.PREVIOUS...
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...
00Z UPDATE...
BACK EDGE OF RAIN MOVING EAST OF ATLANTA AND METRO TAF SITES BUT
PERIODS OF DRIZZLE AND ADDITIONAL SHOWERS EXPECTED THROUGH THE
NIGHT. LOOKS LIKE A PERSISTENCE FORECAST WITH IFR TO CONTINUE INTO
THE EVENING HOURS...TRANSITIONING TO A LONG PERIOD OF LIFR INTO THE
OVERNIGHT PERIOD...GRADUALLY BECOMING LOW MVFR BY LATE AFTERNOON
SUNDAY. WINDS EAST THROUGH TONIGHT BECOMING MORE SOUTH OF EAST
AROUND 10KT AFTER 15Z SUNDAY.
//ATL CONFIDENCE...00Z UPDATE...
MEDIUM TO HIGH ON ALL ELEMENTS.
41
&&
.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...41
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
745 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...
00Z UPDATE...
BACK EDGE OF RAIN MOVING EAST OF ATLANTA AND METRO TAF SITES BUT
PERIODS OF DRIZZLE AND ADDITIONAL SHOWERS EXPECTED THROUGH THE
NIGHT. LOOKS LIKE A PERSISTENCE FORECAST WITH IFR TO CONTINUE INTO
THE EVENING HOURS...TRANSITIONING TO A LONG PERIOD OF LIFR INTO THE
OVERNIGHT PERIOD...GRADUALLY BECOMING LOW MVFR BY LATE AFTERNOON
SUNDAY. WINDS EAST THROUGH TONIGHT BECOMING MORE SOUTH OF EAST
AROUND 10KT AFTER 15Z SUNDAY.
//ATL CONFIDENCE...00Z UPDATE...
MEDIUM TO HIGH ON ALL ELEMENTS.
41
&&
.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...41
AREA FORECAST DISCUSSION
NWS JACKSON KY
134 PM EDT FRI AUG 16 2013
.UPDATE...
ISSUED AT 1228 PM EDT FRI AUG 16 2013
LATEST HRRR RUNS ARE CONSISTENT WITH RUNS EARLIER THIS MORNING
POINTING TOWARDS SCATTERED SHOWERS OVER THE SOUTHERN...AND ESPECIALLY
SOUTHWEST PART OF FORECAST AREA. WILL KEEP THE PRECIPITATION FORECAST
AS IS FOR THIS AFTERNOON. MADE SOME MINOR ADJUSTMENTS TO NDFD FOR
LATEST OBSERVATIONAL TRENDS.
UPDATE ISSUED AT 1028 AM EDT FRI AUG 16 2013
A FEW SHOWERS HAVE DEVELOPED OVER SOUTH CENTRAL KY WEST OF OUR
FORECAST AREA AND OVER CENTRAL TN. THE 12Z NAM AND HRRR CONTINUE TO
POINT TOWARDS THE POSSIBILITY OF SHOWERS OVER THE SOUTHERN PART OF
THE FORECAST AREA THIS AFTERNOON...IN GOOD AGREEMENT WITH INHERITED
FORECAST. WILL CONTINUE WITH SAME AREA FOR SHOWER POSSIBILITY THIS
AFTERNOON. EXTENSIVE CLOUD COVER OVER TN HAS WORKED INTO THE SW PART
OF THE FORECAST AREA...AND HAVE MADE ADJUSTMENTS TO SKY COVER GRIDS.
THE CLOUDS WILL INHIBIT CONVECTIVE DEVELOPMENT...AND WILL CHANGE
SCATTERED SHOWERS AND THUNDERSTORMS TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS. NDFD AND ASSOCIATED PRODUCTS...INCLUDING ZFP...HAVE
BEEN UPDATED.
UPDATE ISSUED AT 723 AM EDT FRI AUG 16 2013
UPDATED THE FORECAST TO BETTER REFLECT CURRENT CONDITIONS AND MODEL
TRENDS. ONLY HAD TO MAKE MINOR TWEAKS TO THE TEMPERATURES AND DEW
POINTS. THE REST OF THE FORECAST IS ON TRACK.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 225 AM EDT FRI AUG 16 2013
THIS HAS BEEN AN UNUSUAL SUMMER AS IT HAS BE DOMINATED BY A UPPER LOW
OVER THE EASTERN PORTION OF THE US AND THE MODELS ARE ONCE AGAIN
BUILDING ANOTHER UPPER LOW IN OVER SOUTHERN ILLINOIS BY THIS EVENING.
WITH THIS TYPE OF PATTERN...THE POSITION OF THE UPPER LOW WILL BE
CRUCIAL AND WILL MAKE A BIG DIFFERENCE IN FORECAST. THE FORECAST IS
ALSO DIFFICULT DUE TO THE LACK OF ANY STRONG ORGANIZED SYSTEMS. THE
WEATHER WILL TEND TO BE DIURNALLY DRIVEN WITH THE BEST CHANCE FOR
CONVECTION BEING INTO THE AFTERNOON AND EARLY EVENING. WILL HAVE TO
WATCH FOR WEAK DISTURBANCES THAT WILL BE ROTATING AROUND THE LOW AND
WILL BE ABLE TO FOCUS SOME ENHANCED ACTIVITY. AT THIS POINT IN
TIME...CONFIDENCE IS LOW THAT THE MODELS WILL HAVE A GOOD HANDLE ON
THIS YET. FOR TODAY...KEPT THE PRECIPITATION MOSTLY WEST OF I 75 AS
ONLY A PORTION OF THE SYSTEM WILL BE ABLE TO INFLUENCE THE AREA.
THERE IS A MARKED DIFFERENCE IN THE NAM BUFFER SOUNDING FOR LONDON AND
JACKSON. AT JACKSON...THERE IS A PERSISTENT CAP IN PLACE THAT SHOULD
BE ABLE TO SUPPRESS THE CONVECTION THIS AFTERNOON. AT LONDON...THE
CAP DISAPPEARS AFTER 2 PM. FOR TEMPERATURES...WENT WITH THE BLEND AS
THERE IS ACTUALLY QUITE A BIT OF SPREAD BETWEEN THE VARIOUS MODELS.
WHEN THIS OCCURS AND ONE OF THE SOLUTIONS DOES NOT STAND OUT...LIKE
TO GO WITH THE BLEND.
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 300 AM EDT FRI AUG 16 2013
THE MODELS WERE IN DECENT AGREEMENT WITH THE OVERALL LARGE SCALE
WEATHER PATTERN IN THE EXTENDED. A PASSING LARGE SCALE UPPER TROUGH
IS EXPECTED TO COMBINE WITH LOW LEVEL MOIST FLOW OFF THE SOUTHWESTERN
ATLANTIC. SOUTHEASTERLY FLOW AROUND THE WESTERN PERIPHERY OF THE
BERMUDA HIGH WILL PROVIDE THE WARM MOIST AIR TO THE REGION. SCATTERED
SHOWERS AND STORMS ARE PROGGED TO FORM MAINLY DURING THE AFTERNOON
AND EVENING HOURS ACROSS CENTRAL AND EASTERN KENTUCKY DURING PEAK
HEATING. THE ACTIVITY IS EXPECTED TO TAPER OFF AFTER SUNSET EACH
DAY...WITH DRY OVERNIGHT PERIODS AND MOSTLY DRY EARLY MORNING PERIODS.
HIGH TEMPERATURES THE FIRST FEW DAYS OF THE PERIOD SHOULD BE COOLER
THAN NORMAL...WITH WIDESPREAD CLOUD COVER AND PRECIPITATION IN THE
FORECAST. HIGHS ON SUNDAY AND MONDAY WILL TOP OUT AROUND 80 DEGREES.
FROM WEDNESDAY ONWARD SHOULD TOP OUT AT OR ABOVE NORMAL...WITH
READINGS IN THE MID TO UPPER 80S EACH DAY UNDER A SOUTHERLY FLOW
REGIME AND PARTLY CLOUDY SKIES. OVERNIGHT LOWS WILL DROP INTO THE
60S...WHICH IS NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 134 PM EDT FRI AUG 16 2013
HIGH PRESSURE OVER THE OHIO VALLEY WILL KEEP MOSTLY VFR CONDITIONS
ACROSS THE FORECAST AREA THROUGH SATURDAY. ISOLATED THUNDERSTORMS WILL
BE POSSIBLE THIS AFTERNOON MAINLY SOUTH OF LOZ AND SME...CLOSER TO
THE TN BORDER. WHILE SOME FOG IN RIVER VALLEYS CAN BE EXPECTED LATE
TONIGHT...FOG IS NOT EXPECTED TO AFFECT THE TAF SITES. MOISTURE WILL
BE INCREASING ACROSS THE AREA ON SATURDAY AS AN UPPER LEVEL LOW
PRESSURE SYSTEM TAKES SHAPE OVER THE MID MS VALLEY...AND THIS WILL
BRING A BETTER CHANCE OF SCATTERED SHOWERS AND THUNDERSTORMS SATURDAY
AFTERNOON.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...JJ
LONG TERM...AR
AVIATION...SBH
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
111 PM EDT Fri Aug 16 2013
...Updated Aviation Discussion...
...Forecast Update...
Issued at 107 PM EDT Fri Aug 16 2013
Current forecast continues to be on track. Most likely will see a
strong gradient of PoP this afternoon with mostly dry conditions
across southern Indiana and north-central and east-central KY. Best
chances for some light showers would be across south-central KY.
Temperatures have warmed into the mid-upper 70s and highs still look
to top out in the in the mid-upper 70s with some locations reaching
80.
Update issued at 1035 AM EDT Fri Aug 16 2013
Did a very minor update to the grids. Basically adjust T/Td grids
over the next few hours and adjust the clouds and PoPs slightly.
Have a bit of moisture convergence down across south-central KY this
morning which has resulted in some scattered showers. Expect this
to continue through the morning and afternoon hours with the best
coverage remaining across southern KY...and lesser chances as one
heads up to the Ohio River. Afternoon highs in the upper 70s to
around 80 still look attainable.
.SHORT TERM (Now through Saturday)...
Issued at 305 AM EDT Fri Aug 16 2013
The main challenge for today will be precipitation chances over
south central KY. Weak convection formed Thurs due to forcing of an
upper level trough and sfc convergence along an inverted trough over
central TN. A line of showers and isld t-storms resulted Thurs
afternoon/evening and has been slowly dissipating and drifting
northward during the early morning hours. Left over sprinkles may
drift into our south central KY counties this morning around and
just after sunrise. A better chance of rain looks to arrive this
afternoon for south central KY if the inverted sfc trough can drift
far enough northward as the 0Z NAM and 3Z RAP suggest it will.
Expect weakly forced showers and isld t-storms to re-fire along the
boundary by mid to late afternoon and again weaken and diminish
after sunset. Although did increase POPs to 30% along the KY/TN
border, there is still some doubt that the boundary will not make it
this far north so will need to monitor closely today. Went a few
degrees cooler than MOS guidance for high temps and MOS guidance was
a few degrees too warm for Thurs highs. This puts the area in the
upper 70s to around 80 for highs this afternoon.
Tonight expect showers/storms to diminish early over south central
KY and become more focused to our west and south overnight as an
upper level wave drops down into the broad Midwest trough forming a
closed low over the mid Mississippi River Valley by Sat afternoon.
It appears that this feature may help pull the inverted sfc trough
back northward over central KY for Sat providing a better focus for
showers/t-storms. Although wind fields and overall forcing still
look meager, perhaps better overall coverage of convection can be
achieved over central KY Sat afternoon. Any storms that develop
today or Sat should not pose a severe weather threat and would be
brief/weak in nature.
Temperatures tonight should fall into the upper 50s and lower 60s
for lows. Highs Saturday afternoon will warm into the upper 70s and
lower 80s with the warmer spots located over southern Indiana which
only has a 20% chance of rain.
.LONG TERM (Saturday Night through Thursday)...
Issued at 300 AM EDT FRI Aug 16 2013
The extended forecast, starting late Saturday, will feature a
wholesale change in the configuration of the jet stream. The polar
jet, which has for several weeks now been locked in a cyclonic flow
around the Great Lakes, will retreat north into a zonal flow along
or just north of the Canadian Border. This pattern is common in
July, during high summer, and will allow a substantial late summer
warmup for the upper Midwest and the Great Lakes.
As this jet lifts north however, a digging shortwave now moving
south across Kansas will help to elongate a residual trough over the
Lower Ohio Valley. Indeed, both the NAM and the GFS closes off this
trough and creates a shallow cutoff low over the Missouri Bootheel
late Saturday. This feature will lift northeast and become absorbed
into the westerlies over Ohio by late Monday.
A tropical disturbance, now over the Yucatan Peninsula, is forecast
to slowly move northwest and may develop in to a tropical storm early
next week, Regardless of the eventual path of this feature, rich
Gulf moisture will stream northeast out of the western Gulf into the
eastern Tennessee Valley and the southern Appalachians from Sunday
into at least Tuesday of next week.
On Sunday and Monday, central Kentucky will lie in a transition
region between mostly clear skies and subsidence across northern
Indiana and the northwest fringes of an increasingly humid airmass
developing over the southern Appalachians. Weak to moderate
instability both Sunday and Monday afternoon will lead to isolated
to scattered showers and thunderstorms, especially along and south
of the Bluegrass Parkway. Think that coverage may be best Sunday
afternoon, aided by the presence of a weak 850mb circulation over
central Kentucky and a possible inverted trough extending northwards
across the Tennessee Valley. Any convection that does develop Sunday
or Monday will be diurnally driven, dissipating in the evening
hours.
Winds early next week will stay quite light. Temperatures, moderated
by possible cloudiness and the continued presence of troughing, will
remain below normal, with highs in the lower 80s by day and the mid
60s at night.
Heights begin to rise over the Lower Ohio Valley Tuesday as the last
vestiges of the eastern trough exits. Weak subsidence associated
with a slowly eastward propagating 500mb ridge over the southern plains will
most likely keep Tuesday through Thursday dry, as is shown in the
preferred ECMWF. We will experience typical late summer weather with
very light winds and pressure gradients, coupled with moderate
humidities and temperatures that, by Thursday afternoon may warm
into the upper 80s to around 90.
&&
.AVIATION (18Z TAF Update)...
Issued at 110 PM EDT Fri Aug 16 2013
VFR conditions are expected to continue through the upcoming TAF
period. Inverted surface trough and moisture convergence axis will
remain in place this afternoon across south-central KY. This
feature should continue to serve as a focus for convection this
afternoon. Showers and perhaps a thunderstorm will be
possible...mainly in the south between KBWG and KSME. So, will keep
a mention of VCSH in the BWG TAF. Light and variable to light NE
winds are expected at all the terminals this afternoon and this
evening. VFR conditions are expected to hold overnight as well and
into the day on Saturday.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........MJ
Short Term.....AMS
Long Term......JSD
Aviation.......MJ
AREA FORECAST DISCUSSION
NWS JACKSON KY
1229 PM EDT FRI AUG 16 2013
.UPDATE...
ISSUED AT 1228 PM EDT FRI AUG 16 2013
LATEST HRRR RUNS ARE CONSISTENT WITH RUNS EARLIER THIS MORNING
POINTING TOWARDS SCATTERED SHOWERS OVER THE SOUTHERN...AND ESPECIALLY
SOUTHWEST PART OF FORECAST AREA. WILL KEEP THE PRECIPITATION FORECAST
AS IS FOR THIS AFTERNOON. MADE SOME MINOR ADJUSTMENTS TO NDFD FOR
LATEST OBSERVATIONAL TRENDS.
UPDATE ISSUED AT 1028 AM EDT FRI AUG 16 2013
A FEW SHOWERS HAVE DEVELOPED OVER SOUTH CENTRAL KY WEST OF OUR
FORECAST AREA AND OVER CENTRAL TN. THE 12Z NAM AND HRRR CONTINUE TO
POINT TOWARDS THE POSSIBILITY OF SHOWERS OVER THE SOUTHERN PART OF
THE FORECAST AREA THIS AFTERNOON...IN GOOD AGREEMENT WITH INHERITED
FORECAST. WILL CONTINUE WITH SAME AREA FOR SHOWER POSSIBILITY THIS
AFTERNOON. EXTENSIVE CLOUD COVER OVER TN HAS WORKED INTO THE SW PART
OF THE FORECAST AREA...AND HAVE MADE ADJUSTMENTS TO SKY COVER GRIDS.
THE CLOUDS WILL INHIBIT CONVECTIVE DEVELOPMENT...AND WILL CHANGE
SCATTERED SHOWERS AND THUNDERSTORMS TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS. NDFD AND ASSOCIATED PRODUCTS...INCLUDING ZFP...HAVE
BEEN UPDATED.
UPDATE ISSUED AT 723 AM EDT FRI AUG 16 2013
UPDATED THE FORECAST TO BETTER REFLECT CURRENT CONDITIONS AND MODEL
TRENDS. ONLY HAD TO MAKE MINOR TWEAKS TO THE TEMPERATURES AND DEW
POINTS. THE REST OF THE FORECAST IS ON TRACK.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 225 AM EDT FRI AUG 16 2013
THIS HAS BEEN AN UNUSUAL SUMMER AS IT HAS BE DOMINATED BY A UPPER LOW
OVER THE EASTERN PORTION OF THE US AND THE MODELS ARE ONCE AGAIN
BUILDING ANOTHER UPPER LOW IN OVER SOUTHERN ILLINOIS BY THIS EVENING.
WITH THIS TYPE OF PATTERN...THE POSITION OF THE UPPER LOW WILL BE
CRUCIAL AND WILL MAKE A BIG DIFFERENCE IN FORECAST. THE FORECAST IS
ALSO DIFFICULT DUE TO THE LACK OF ANY STRONG ORGANIZED SYSTEMS. THE
WEATHER WILL TEND TO BE DIURNALLY DRIVEN WITH THE BEST CHANCE FOR
CONVECTION BEING INTO THE AFTERNOON AND EARLY EVENING. WILL HAVE TO
WATCH FOR WEAK DISTURBANCES THAT WILL BE ROTATING AROUND THE LOW AND
WILL BE ABLE TO FOCUS SOME ENHANCED ACTIVITY. AT THIS POINT IN
TIME...CONFIDENCE IS LOW THAT THE MODELS WILL HAVE A GOOD HANDLE ON
THIS YET. FOR TODAY...KEPT THE PRECIPITATION MOSTLY WEST OF I 75 AS
ONLY A PORTION OF THE SYSTEM WILL BE ABLE TO INFLUENCE THE AREA.
THERE IS A MARKED DIFFERENCE IN THE NAM BUFFER SOUNDING FOR LONDON AND
JACKSON. AT JACKSON...THERE IS A PERSISTENT CAP IN PLACE THAT SHOULD
BE ABLE TO SUPPRESS THE CONVECTION THIS AFTERNOON. AT LONDON...THE
CAP DISAPPEARS AFTER 2 PM. FOR TEMPERATURES...WENT WITH THE BLEND AS
THERE IS ACTUALLY QUITE A BIT OF SPREAD BETWEEN THE VARIOUS MODELS.
WHEN THIS OCCURS AND ONE OF THE SOLUTIONS DOES NOT STAND OUT...LIKE
TO GO WITH THE BLEND.
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 300 AM EDT FRI AUG 16 2013
THE MODELS WERE IN DECENT AGREEMENT WITH THE OVERALL LARGE SCALE
WEATHER PATTERN IN THE EXTENDED. A PASSING LARGE SCALE UPPER TROUGH
IS EXPECTED TO COMBINE WITH LOW LEVEL MOIST FLOW OFF THE SOUTHWESTERN
ATLANTIC. SOUTHEASTERLY FLOW AROUND THE WESTERN PERIPHERY OF THE
BERMUDA HIGH WILL PROVIDE THE WARM MOIST AIR TO THE REGION. SCATTERED
SHOWERS AND STORMS ARE PROGGED TO FORM MAINLY DURING THE AFTERNOON
AND EVENING HOURS ACROSS CENTRAL AND EASTERN KENTUCKY DURING PEAK
HEATING. THE ACTIVITY IS EXPECTED TO TAPER OFF AFTER SUNSET EACH
DAY...WITH DRY OVERNIGHT PERIODS AND MOSTLY DRY EARLY MORNING PERIODS.
HIGH TEMPERATURES THE FIRST FEW DAYS OF THE PERIOD SHOULD BE COOLER
THAN NORMAL...WITH WIDESPREAD CLOUD COVER AND PRECIPITATION IN THE
FORECAST. HIGHS ON SUNDAY AND MONDAY WILL TOP OUT AROUND 80 DEGREES.
FROM WEDNESDAY ONWARD SHOULD TOP OUT AT OR ABOVE NORMAL...WITH
READINGS IN THE MID TO UPPER 80S EACH DAY UNDER A SOUTHERLY FLOW
REGIME AND PARTLY CLOUDY SKIES. OVERNIGHT LOWS WILL DROP INTO THE
60S...WHICH IS NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 723 AM EDT FRI AUG 16 2013
HIGH PRESSURE OVER THE OHIO VALLEY WILL KEEP MOSTLY VFR CONDITIONS
ACROSS THE FORECAST AREA THROUGH SATURDAY. THERE WAS NOT ANY FOG AT
THE TAF SITES THIS MORNING AND ALTHOUGH WE DO EXPECT SOME MVFR
VISIBILITY IN FOG AROUND DAYBREAK SATURDAY IN MANY OF OUR VALLEY
LOCATIONS THE FLOW FROM THE NORTHEAST IS NOT CONDUCIVE FOR FOG OR
FOG ADVECTION AT OUR TAF SITES. THIS AFTERNOON...THERE MAY BE SOME
CONVECTION WEST OF A LINE FROM PULASKI TO BELL COUNTIES. PUT SOME
VCSH AT SME...BUT NOT AT LONDON AS THE SYSTEM SHOULD STAY TO THE
WEST.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...JJ
LONG TERM...AR
AVIATION...JJ
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1036 AM EDT Fri Aug 16 2013
...Forecast Update...
Issued at 1035 AM EDT Fri Aug 16 2013
Did a very minor update to the grids. Basically adjust T/Td grids
over the next few hours and adjust the clouds and PoPs slightly.
Have a bit of moisture convergence down across south-central KY this
morning which has resulted in some scattered showers. Expect this
to continue through the morning and afternoon hours with the best
coverage remaining across southern KY...and lesser chances as one
heads up to the Ohio River. Afternoon highs in the upper 70s to
around 80 still look attainable.
.SHORT TERM (Now through Saturday)...
Issued at 305 AM EDT Fri Aug 16 2013
The main challenge for today will be precipitation chances over
south central KY. Weak convection formed Thurs due to forcing of an
upper level trough and sfc convergence along an inverted trough over
central TN. A line of showers and isld t-storms resulted Thurs
afternoon/evening and has been slowly dissipating and drifting
northward during the early morning hours. Left over sprinkles may
drift into our south central KY counties this morning around and
just after sunrise. A better chance of rain looks to arrive this
afternoon for south central KY if the inverted sfc trough can drift
far enough northward as the 0Z NAM and 3Z RAP suggest it will.
Expect weakly forced showers and isld t-storms to re-fire along the
boundary by mid to late afternoon and again weaken and diminish
after sunset. Although did increase POPs to 30% along the KY/TN
border, there is still some doubt that the boundary will not make it
this far north so will need to monitor closely today. Went a few
degrees cooler than MOS guidance for high temps and MOS guidance was
a few degrees too warm for Thurs highs. This puts the area in the
upper 70s to around 80 for highs this afternoon.
Tonight expect showers/storms to diminish early over south central
KY and become more focused to our west and south overnight as an
upper level wave drops down into the broad Midwest trough forming a
closed low over the mid Mississippi River Valley by Sat afternoon.
It appears that this feature may help pull the inverted sfc trough
back northward over central KY for Sat providing a better focus for
showers/t-storms. Although wind fields and overall forcing still
look meager, perhaps better overall coverage of convection can be
achieved over central KY Sat afternoon. Any storms that develop
today or Sat should not pose a severe weather threat and would be
brief/weak in nature.
Temperatures tonight should fall into the upper 50s and lower 60s
for lows. Highs Saturday afternoon will warm into the upper 70s and
lower 80s with the warmer spots located over southern Indiana which
only has a 20% chance of rain.
.LONG TERM (Saturday Night through Thursday)...
Issued at 300 AM EDT FRI Aug 16 2013
The extended forecast, starting late Saturday, will feature a
wholesale change in the configuration of the jet stream. The polar
jet, which has for several weeks now been locked in a cyclonic flow
around the Great Lakes, will retreat north into a zonal flow along
or just north of the Canadian Border. This pattern is common in
July, during high summer, and will allow a substantial late summer
warmup for the upper Midwest and the Great Lakes.
As this jet lifts north however, a digging shortwave now moving
south across Kansas will help to elongate a residual trough over the
Lower Ohio Valley. Indeed, both the NAM and the GFS closes off this
trough and creates a shallow cutoff low over the Missouri Bootheel
late Saturday. This feature will lift northeast and become absorbed
into the westerlies over Ohio by late Monday.
A tropical disturbance, now over the Yucatan Peninsula, is forecast
to slowly move northwest and may develop in to a tropical storm early
next week, Regardless of the eventual path of this feature, rich
Gulf moisture will stream northeast out of the western Gulf into the
eastern Tennessee Valley and the southern Appalachians from Sunday
into at least Tuesday of next week.
On Sunday and Monday, central Kentucky will lie in a transition
region between mostly clear skies and subsidence across northern
Indiana and the northwest fringes of an increasingly humid airmass
developing over the southern Appalachians. Weak to moderate
instability both Sunday and Monday afternoon will lead to isolated
to scattered showers and thunderstorms, especially along and south
of the Bluegrass Parkway. Think that coverage may be best Sunday
afternoon, aided by the presence of a weak 850mb circulation over
central Kentucky and a possible inverted trough extending northwards
across the Tennessee Valley. Any convection that does develop Sunday
or Monday will be diurnally driven, dissipating in the evening
hours.
Winds early next week will stay quite light. Temperatures, moderated
by possible cloudiness and the continued presence of troughing, will
remain below normal, with highs in the lower 80s by day and the mid
60s at night.
Heights begin to rise over the Lower Ohio Valley Tuesday as the last
vestiges of the eastern trough exits. Weak subsidence associated
with a slowly eastward propagating 500mb ridge over the southern plains will
most likely keep Tuesday through Thursday dry, as is shown in the
preferred ECMWF. We will experience typical late summer weather with
very light winds and pressure gradients, coupled with moderate
humidities and temperatures that, by Thursday afternoon may warm
into the upper 80s to around 90.
&&
.AVIATION (12Z TAF Update)...
Issued at 645 AM EDT Fri Aug 16 2013
VFR conditions are expected for this TAF period. An inverted sfc
trough and an upper level trough are expected to spark weak
convection near BWG this afternoon. Can`t rule out a sprinkle or
two this morning, but will hold off on a VCSH mention until better
instability/convergence organize this afternoon. A rumble of
thunder is also possible near BWG this afternoon, but chances are
too slim to mention in the TAFs at this point. Winds will continue
out of the NE at all terminals through the TAF period with max winds
between 5-7 kts this afternoon.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........MJ
Short Term.....AMS
Long Term......JSD
Aviation.......AMS
AREA FORECAST DISCUSSION
NWS JACKSON KY
1029 AM EDT FRI AUG 16 2013
.UPDATE...
ISSUED AT 1028 AM EDT FRI AUG 16 2013
A FEW SHOWERS HAVE DEVELOPED OVER SOUTH CENTRAL KY WEST OF OUR
FORECAST AREA AND OVER CENTRAL TN. THE 12Z NAM AND HRRR CONTINUE TO
POINT TOWARDS THE POSSIBILITY OF SHOWERS OVER THE SOUTHERN PART OF
THE FORECAST AREA THIS AFTERNOON...IN GOOD AGREEMENT WITH INHERITED
FORECAST. WILL CONTINUE WITH SAME AREA FOR SHOWER POSSIBILITY THIS
AFTERNOON. EXTENSIVE CLOUD COVER OVER TN HAS WORKED INTO THE SW PART
OF THE FORECAST AREA...AND HAVE MADE ADJUSTMENTS TO SKY COVER GRIDS.
THE CLOUDS WILL INHIBIT CONVECTIVE DEVELOPMENT...AND WILL CHANGE
SCATTERED SHOWERS AND THUNDERSTORMS TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS. NDFD AND ASSOCIATED PRODUCTS...INCLUDING ZFP...HAVE
BEEN UPDATED.
UPDATE ISSUED AT 723 AM EDT FRI AUG 16 2013
UPDATED THE FORECAST TO BETTER REFLECT CURRENT CONDITIONS AND MODEL
TRENDS. ONLY HAD TO MAKE MINOR TWEAKS TO THE TEMPERATURES AND DEW
POINTS. THE REST OF THE FORECAST IS ON TRACK.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 225 AM EDT FRI AUG 16 2013
THIS HAS BEEN AN UNUSUAL SUMMER AS IT HAS BE DOMINATED BY A UPPER LOW
OVER THE EASTERN PORTION OF THE US AND THE MODELS ARE ONCE AGAIN
BUILDING ANOTHER UPPER LOW IN OVER SOUTHERN ILLINOIS BY THIS EVENING.
WITH THIS TYPE OF PATTERN...THE POSITION OF THE UPPER LOW WILL BE
CRUCIAL AND WILL MAKE A BIG DIFFERENCE IN FORECAST. THE FORECAST IS
ALSO DIFFICULT DUE TO THE LACK OF ANY STRONG ORGANIZED SYSTEMS. THE
WEATHER WILL TEND TO BE DIURNALLY DRIVEN WITH THE BEST CHANCE FOR
CONVECTION BEING INTO THE AFTERNOON AND EARLY EVENING. WILL HAVE TO
WATCH FOR WEAK DISTURBANCES THAT WILL BE ROTATING AROUND THE LOW AND
WILL BE ABLE TO FOCUS SOME ENHANCED ACTIVITY. AT THIS POINT IN
TIME...CONFIDENCE IS LOW THAT THE MODELS WILL HAVE A GOOD HANDLE ON
THIS YET. FOR TODAY...KEPT THE PRECIPITATION MOSTLY WEST OF I 75 AS
ONLY A PORTION OF THE SYSTEM WILL BE ABLE TO INFLUENCE THE AREA.
THERE IS A MARKED DIFFERENCE IN THE NAM BUFFER SOUNDING FOR LONDON AND
JACKSON. AT JACKSON...THERE IS A PERSISTENT CAP IN PLACE THAT SHOULD
BE ABLE TO SUPPRESS THE CONVECTION THIS AFTERNOON. AT LONDON...THE
CAP DISAPPEARS AFTER 2 PM. FOR TEMPERATURES...WENT WITH THE BLEND AS
THERE IS ACTUALLY QUITE A BIT OF SPREAD BETWEEN THE VARIOUS MODELS.
WHEN THIS OCCURS AND ONE OF THE SOLUTIONS DOES NOT STAND OUT...LIKE
TO GO WITH THE BLEND.
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 300 AM EDT FRI AUG 16 2013
THE MODELS WERE IN DECENT AGREEMENT WITH THE OVERALL LARGE SCALE
WEATHER PATTERN IN THE EXTENDED. A PASSING LARGE SCALE UPPER TROUGH
IS EXPECTED TO COMBINE WITH LOW LEVEL MOIST FLOW OFF THE SOUTHWESTERN
ATLANTIC. SOUTHEASTERLY FLOW AROUND THE WESTERN PERIPHERY OF THE
BERMUDA HIGH WILL PROVIDE THE WARM MOIST AIR TO THE REGION. SCATTERED
SHOWERS AND STORMS ARE PROGGED TO FORM MAINLY DURING THE AFTERNOON
AND EVENING HOURS ACROSS CENTRAL AND EASTERN KENTUCKY DURING PEAK
HEATING. THE ACTIVITY IS EXPECTED TO TAPER OFF AFTER SUNSET EACH
DAY...WITH DRY OVERNIGHT PERIODS AND MOSTLY DRY EARLY MORNING PERIODS.
HIGH TEMPERATURES THE FIRST FEW DAYS OF THE PERIOD SHOULD BE COOLER
THAN NORMAL...WITH WIDESPREAD CLOUD COVER AND PRECIPITATION IN THE
FORECAST. HIGHS ON SUNDAY AND MONDAY WILL TOP OUT AROUND 80 DEGREES.
FROM WEDNESDAY ONWARD SHOULD TOP OUT AT OR ABOVE NORMAL...WITH
READINGS IN THE MID TO UPPER 80S EACH DAY UNDER A SOUTHERLY FLOW
REGIME AND PARTLY CLOUDY SKIES. OVERNIGHT LOWS WILL DROP INTO THE
60S...WHICH IS NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 723 AM EDT FRI AUG 16 2013
HIGH PRESSURE OVER THE OHIO VALLEY WILL KEEP MOSTLY VFR CONDITIONS
ACROSS THE FORECAST AREA THROUGH SATURDAY. THERE WAS NOT ANY FOG AT
THE TAF SITES THIS MORNING AND ALTHOUGH WE DO EXPECT SOME MVFR
VISIBILITY IN FOG AROUND DAYBREAK SATURDAY IN MANY OF OUR VALLEY
LOCATIONS THE FLOW FROM THE NORTHEAST IS NOT CONDUCIVE FOR FOG OR
FOG ADVECTION AT OUR TAF SITES. THIS AFTERNOON...THERE MAY BE SOME
CONVECTION WEST OF A LINE FROM PULASKI TO BELL COUNTIES. PUT SOME
VCSH AT SME...BUT NOT AT LONDON AS THE SYSTEM SHOULD STAY TO THE
WEST.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...JJ
LONG TERM...AR
AVIATION...JJ
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
645 AM EDT Fri Aug 16 2013
...Updated Aviation Discussion...
.SHORT TERM (Now through Saturday)...
Issued at 305 AM EDT Fri Aug 16 2013
The main challenge for today will be precipitation chances over
south central KY. Weak convection formed Thurs due to forcing of an
upper level trough and sfc convergence along an inverted trough over
central TN. A line of showers and isld t-storms resulted Thurs
afternoon/evening and has been slowly dissipating and drifting
northward during the early morning hours. Left over sprinkles may
drift into our south central KY counties this morning around and
just after sunrise. A better chance of rain looks to arrive this
afternoon for south central KY if the inverted sfc trough can drift
far enough northward as the 0Z NAM and 3Z RAP suggest it will.
Expect weakly forced showers and isld t-storms to re-fire along the
boundary by mid to late afternoon and again weaken and diminish
after sunset. Although did increase POPs to 30% along the KY/TN
border, there is still some doubt that the boundary will not make it
this far north so will need to monitor closely today. Went a few
degrees cooler than MOS guidance for high temps and MOS guidance was
a few degrees too warm for Thurs highs. This puts the area in the
upper 70s to around 80 for highs this afternoon.
Tonight expect showers/storms to diminish early over south central
KY and become more focused to our west and south overnight as an
upper level wave drops down into the broad Midwest trough forming a
closed low over the mid Mississippi River Valley by Sat afternoon.
It appears that this feature may help pull the inverted sfc trough
back northward over central KY for Sat providing a better focus for
showers/t-storms. Although wind fields and overall forcing still
look meager, perhaps better overall coverage of convection can be
achieved over central KY Sat afternoon. Any storms that develop
today or Sat should not pose a severe weather threat and would be
brief/weak in nature.
Temperatures tonight should fall into the upper 50s and lower 60s
for lows. Highs Saturday afternoon will warm into the upper 70s and
lower 80s with the warmer spots located over southern Indiana which
only has a 20% chance of rain.
.LONG TERM (Saturday Night through Thursday)...
Issued at 300 AM EDT FRI Aug 16 2013
The extended forecast, starting late Saturday, will feature a
wholesale change in the configuration of the jet stream. The polar
jet, which has for several weeks now been locked in a cyclonic flow
around the Great Lakes, will retreat north into a zonal flow along
or just north of the Canadian Border. This pattern is common in
July, during high summer, and will allow a substantial late summer
warmup for the upper Midwest and the Great Lakes.
As this jet lifts north however, a digging shortwave now moving
south across Kansas will help to elongate a residual trough over the
Lower Ohio Valley. Indeed, both the NAM and the GFS closes off this
trough and creates a shallow cutoff low over the Missouri Bootheel
late Saturday. This feature will lift northeast and become absorbed
into the westerlies over Ohio by late Monday.
A tropical disturbance, now over the Yucatan Peninsula, is forecast
to slowly move northwest and may develop in to a tropical storm early
next week, Regardless of the eventual path of this feature, rich
Gulf moisture will stream northeast out of the western Gulf into the
eastern Tennessee Valley and the southern Appalachians from Sunday
into at least Tuesday of next week.
On Sunday and Monday, central Kentucky will lie in a transition
region between mostly clear skies and subsidence across northern
Indiana and the northwest fringes of an increasingly humid airmass
developing over the southern Appalachians. Weak to moderate
instability both Sunday and Monday afternoon will lead to isolated
to scattered showers and thunderstorms, especially along and south
of the Bluegrass Parkway. Think that coverage may be best Sunday
afternoon, aided by the presence of a weak 850mb circulation over
central Kentucky and a possible inverted trough extending northwards
across the Tennessee Valley. Any convection that does develop Sunday
or Monday will be diurnally driven, dissipating in the evening
hours.
Winds early next week will stay quite light. Temperatures, moderated
by possible cloudiness and the continued presence of troughing, will
remain below normal, with highs in the lower 80s by day and the mid
60s at night.
Heights begin to rise over the Lower Ohio Valley Tuesday as the last
vestiges of the eastern trough exits. Weak subsidence associated
with a slowly eastward propagating 500mb ridge over the southern plains will
most likely keep Tuesday through Thursday dry, as is shown in the
preferred ECMWF. We will experience typical late summer weather with
very light winds and pressure gradients, coupled with moderate
humidities and temperatures that, by Thursday afternoon may warm
into the upper 80s to around 90.
&&
.AVIATION (12Z TAF Update)...
Issued at 645 AM EDT Fri Aug 16 2013
VFR conditions are expected for this TAF period. An inverted sfc
trough and an upper level trough are expected to spark weak
convection near BWG this afternoon. Can`t rule out a sprinkle or
two this morning, but will hold off on a VCSH mention until better
instability/convergence organize this afternoon. A rumble of
thunder is also possible near BWG this afternoon, but chances are
too slim to mention in the TAFs at this point. Winds will continue
out of the NE at all terminals through the TAF period with max winds
between 5-7 kts this afternoon.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Short Term........AMS
Long Term.........JSD
Aviation..........AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
310 AM EDT Fri Aug 16 2013
.SHORT TERM (Now through Saturday)...
Issued at 305 AM EDT Fri Aug 16 2013
The main challenge for today will be precipitation chances over
south central KY. Weak convection formed Thurs due to forcing of an
upper level trough and sfc convergence along an inverted trough over
central TN. A line of showers and isld t-storms resulted Thurs
afternoon/evening and has been slowly dissipating and drifting
northward during the early morning hours. Left over sprinkles may
drift into our south central KY counties this morning around and
just after sunrise. A better chance of rain looks to arrive this
afternoon for south central KY if the inverted sfc trough can drift
far enough northward as the 0Z NAM and 3Z RAP suggest it will.
Expect weakly forced showers and isld t-storms to re-fire along the
boundary by mid to late afternoon and again weaken and diminish
after sunset. Although did increase POPs to 30% along the KY/TN
border, there is still some doubt that the boundary will not make it
this far north so will need to monitor closely today. Went a few
degrees cooler than MOS guidance for high temps and MOS guidance was
a few degrees too warm for Thurs highs. This puts the area in the
upper 70s to around 80 for highs this afternoon.
Tonight expect showers/storms to diminish early over south central
KY and become more focused to our west and south overnight as an
upper level wave drops down into the broad Midwest trough forming a
closed low over the mid Mississippi River Valley by Sat afternoon.
It appears that this feature may help pull the inverted sfc trough
back northward over central KY for Sat providing a better focus for
showers/t-storms. Although wind fields and overall forcing still
look meager, perhaps better overall coverage of convection can be
achieved over central KY Sat afternoon. Any storms that develop
today or Sat should not pose a severe weather threat and would be
brief/weak in nature.
Temperatures tonight should fall into the upper 50s and lower 60s
for lows. Highs Saturday afternoon will warm into the upper 70s and
lower 80s with the warmer spots located over southern Indiana which
only has a 20% chance of rain.
.LONG TERM (Saturday Night through Thursday)...
Issued at 300 AM EDT FRI Aug 16 2013
The extended forecast, starting late Saturday, will feature a
wholesale change in the configuration of the jet stream. The polar
jet, which has for several weeks now been locked in a cyclonic flow
around the Great Lakes, will retreat north into a zonal flow along
or just north of the Canadian Border. This pattern is common in
July, during high summer, and will allow a substantial late summer
warmup for the upper Midwest and the Great Lakes.
As this jet lifts north however, a digging shortwave now moving
south across Kansas will help to elongate a residual trough over the
Lower Ohio Valley. Indeed, both the NAM and the GFS closes off this
trough and creates a shallow cutoff low over the Missouri Bootheel
late Saturday. This feature will lift northeast and become absorbed
into the westerlies over Ohio by late Monday.
A tropical disturbance, now over the Yucatan Peninsula, is forecast
to slowly move northwest and may develop in to a tropical storm early
next week, Regardless of the eventual path of this feature, rich
Gulf moisture will stream northeast out of the western Gulf into the
eastern Tennessee Valley and the southern Appalachians from Sunday
into at least Tuesday of next week.
On Sunday and Monday, central Kentucky will lie in a transition
region between mostly clear skies and subsidence across northern
Indiana and the northwest fringes of an increasingly humid airmass
developing over the southern Appalachians. Weak to moderate
instability both Sunday and Monday afternoon will lead to isolated
to scattered showers and thunderstorms, especially along and south
of the Bluegrass Parkway. Think that coverage may be best Sunday
afternoon, aided by the presence of a weak 850mb circulation over
central Kentucky and a possible inverted trough extending northwards
across the Tennessee Valley. Any convection that does develop Sunday
or Monday will be diurnally driven, dissipating in the evening
hours.
Winds early next week will stay quite light. Temperatures, moderated
by possible cloudiness and the continued presence of troughing, will
remain below normal, with highs in the lower 80s by day and the mid
60s at night.
Heights begin to rise over the Lower Ohio Valley Tuesday as the last
vestiges of the eastern trough exits. Weak subsidence associated
with a slowly eastward propagating 500mb ridge over the southern plains will
most likely keep Tuesday through Thursday dry, as is shown in the
preferred ECMWF. We will experience typical late summer weather with
very light winds and pressure gradients, coupled with moderate
humidities and temperatures that, by Thursday afternoon may warm
into the upper 80s to around 90.
&&
.AVIATION (06Z TAF Update)...
Issued at 115 AM EDT Fri Aug 16 2013
VFR conditions are expected for this TAF period. An inverted sfc
trough over TN and an upper level trough will continue to spark weak
convection mainly to the south of BWG, however, can`t rule out a
sprinkle or shower at BWG today. Low level moisture return looks to
scant to make a VCSH shower mention in the TAF at this time. Plus,
a drier NE wind will continue at the terminal further inhibiting
shower chances. Winds will continue out of the NE at all terminals
through the TAF period with max winds between 6-8 kts this afternoon.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Short Term........AMS
Long Term.........JSD
Aviation..........AMS
AREA FORECAST DISCUSSION
NWS CARIBOU ME
610 AM EDT FRI AUG 16 2013
.SYNOPSIS...
A COLD FRONT WILL BECOME STATIONARY OVER NORTH CENTRAL PORTIONS OF
THE REGION TODAY...THEN MOVE SOUTHEAST OF THE REGION TONIGHT. HIGH
PRESSURE WILL THEN BUILD ACROSS THE REGION THROUGH THE WEEKEND
INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
6 AM UPDATE: WITH PATCHY FOG ALREADY BEGINNING TO DISSIPATE THIS
HR...WE TOOK THE MENTION OF FOG OUT OF ZONE FORECAST TEXTS. ALSO...
WE UPDATED THE PRIOR NGT`S FCST LOW WITH OBSVD HRLY TEMPS AT 5-6
AM...THEN RE-INTERPOLATED THE HRLY TEMP FCST TO POSTED MID AFTN HI
TEMPS. OTHERWISE...NO CHGS WERE MADE TO THE CURRENT FCST TMG OF
CLDS...POPS AND WX GRIDS...WITH ENSM MODEL DATA FROM THE BOTH THE
SREF AND GFS AS WELL AS HRLY HRRR SIMULATED MODEL RADAR REF
SUPPORTING A VERY SIMILAR SCENARIO TO OUR FCST INTO THE ERLY EVE.
ORGNL DISC: THE CONSENSUS OF MODELS IN THE NEAR TERM CONT TO SHOW
THE PROGRESSION OF AN UPPER TROF FROM ERN QB THIS MORN ACROSS NRN
ME THIS AFTN AND INTO NB THIS EVE. MEANWHILE...A SFC COLD FRONT IS
IS EXPECTED TO STALL OVR N CNTRL PTNS OF THE FA BEFORE MOVG SE
AGAIN TONIGHT. THE COMBINATION OF THESE TWO FACTORS WILL RESULT IN
MORE GENERAL SHWR AND SCT TSTM CVRG ACROSS NRN AND CNTRL PTNS OF
THE FA THAN YSTDY...WITH LIKELY POPS JUSTIFIED BASED ON OUR FCST
OF AREAL BASIN QPF...SPCLY IN THE 2-8PM TM FRAME. THE PROGRESSION
OF SHWRS AND TSTMS TO THE ESE THIS AFTN AND ERLY EVE FROM FAR NRN
ME MIDDAY WILL BE TIED TO THE EVOLUTION OF SBCAPE DURG THIS TM
FRAME... WITH SBCAPE XPCTD TO MAXIMIZE SOMEWHERE BETWEEN 500 AND
1000J/KG OVR NE AND E CNTRL PTNS OF THE FA BY LATE AFTN. FOR THIS
REASON... ALG WITH WITH LOW FZG AND -20 DEG C LVLS...WE ADDED
ENHANCED WORDING FOR A FEW STORMS CONTAINING SMALL HAIL AND
LOCALIZED STRONG WIND GUSTS. HI TEMPS WILL ONCE AGAIN WILL BE
BELOW NORMAL FOR THIS DATE BY ABOUT 5 DEG F.
SHWRS AND TSTMS SHOULD SLOWLY DISSIPATE AND MOVE ESE OUT OF THE
FA WITH THE LOSS OF HTG AND THE PASSAGE OF THE UPPER TROF E OF THE
REGION. THIS WILL ALLOW FOR CLRG TO WORK IN FROM WRN AREAS LATE
THIS EVE TO THE REST OF THE FA LATE TNGT. ALTHOUGH WINDS WILL BE
LGT...THE LESSER WINDOW OF CLR SKIES WILL KEEP OVRNGT LOWS FROM
REACHING QUITE AS LOW AS PREVIOUSLY THOUGHT. WITH WET GROUNDS
FROM AFT/ERLY EVE RNFL HOWEVER...PATCHY FOG WILL BE POSSIBLE
LATE TNGT...WITH WEAK LLVL COOL/DRY ADVCN WORKING AGAINST THE
POTENTIAL OF MORE WIDESPREAD AND DENSE FOG ATTM...BUT THIS WILL
NEED TO BE MONITORED.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
HIGH PRESSURE WILL BRING DRY CONDITIONS AND HIGHS IN THE MID TO UPPER
70S SATURDAY AND LOW 80S ON SUNDAY. HUMIDITY WILL BE LOW THROUGH
THE WEEKEND. CLOUD COVER WILL BE MORE WIDESPREAD SATURDAY
AFTERNOON WITH CU AND STRATOCU FIELDS DUE TO H850 MOISTURE. AFTER
THESE CLOUDS DISSIPATE...LOWS SATURDAY NIGHT WILL DIP TO THE UPPER
40S TO LOW 50S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
HIGH PRESSURE AND WARM AIR ADVECTION WILL PRODUCE HIGHS IN LOW TO
MID 80S MONDAY. SOUTHWEST WINDS WILL INCREASE WITH GUSTS TO 20
MPH. A COLD FRONT WILL APPROACH MONDAY NIGHT. THE BIG QUESTION IS
WHETHER IT WILL MAKE IT INTO THE FORECAST AREA OR JUST REACH THE
FORECAST AREA AND STALL. THIS FRONT WILL INTRODUCE HIGH HUMIDITY
THAT WILL LINGER FOR THE REST OF THE WEEK. HAVE GONE WITH MUCH MORE
CLOUDS AND LOWER TEMPERATURES IN NORTHERN ZONES FOR TUESDAY. ALSO
ADDED A CHANCE OF SHOWERS IN THE NORTHERN ZONES. THE FRONT IS
EXPECTED TO MOVE BACK NORTH FOR WEDNESDAY WITH HIGH PRESSURE BACK
IN CONTROL AND HIGHS IN THE UPPER 70S TO LOW 80S. ANOTHER FRONT IS
EXPECTED THURSDAY WITH A SLIGHT CHANCE OF SHOWERS.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: MSLY VFR FOR OUR TAF SITES XCPT LCLY MVFR/IFR IN PATCHY
FOG ERLY THIS MORN AND LATE TNGT...BRIEFLY IN ANY DOWNPOURS WITH
ANY TSTMS OR HEAVIER SHWRS THIS AFTN INTO ERLY EVE.
SHORT TERM: VFR EXPECTED OUTSIDE OF PATCHY FOG NEAR SUNRISE SUNDAY
MORNING. MVFR CIGS ARE POSSIBLE TUESDAY NORTH OF HUL.
&&
.MARINE...
NEAR TERM: NO HDLNS ANTICIPATED WITH WV HTS OVR OUTER MZS SLOWLY
SUBSIDING BLO 3 FT AND NEAR COASTLINE WV HTS IN THE 1 TO 2 FT
RANGE. USED A BLEND OF WW3 AND SWAN NAM FOR FCST WV HTS...SMOOTHED
ALG THE IMMEDIATE COASTLINE 10X TO LOWER WV HTS WITH A MIN WV HT
OF 1 FOOT.
SHORT TERM: LIGHT WINDS AND SEAS 2 FEET OR LESS ARE EXPECTED WITH
HIGH PRESSURE IN CONTROL. WINDS MAY GUST TOWARDS 15 KTS ON MONDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...VJN
SHORT TERM...MCW
LONG TERM...MCW
AVIATION...VJN/MCW
MARINE...VJN/MCW
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1024 PM EDT SAT AUG 17 2013
.SYNOPSIS...
AN UPPER-LEVEL DISTURBANCE WILL BRING INCREASED CHANCES FOR RAIN
SOUTH OF PITTSBURGH TONIGHT AND TOMORROW...AND ALL LOCATIONS
SUNDAY NIGHT AND MONDAY. HIGH PRESSURE BY MID-WEEK WILL PROVIDE
DRY AND WARM CONDITIONS.
&&
.NEAR TERM /THROUGH SUNDAY/...
MOISTURE BETWEEN A SLOW MOVING UPPER LOW OVER THE MID-MISSISSIPPI
VALLEY AND A DEVELOPING SURFACE LOW ALONG THE CAROLINA COAST WILL
CONTINUE TO STREAM NORTHWARD OVERNIGHT. AT THIS POINT MOST OF THE
PRECIPITATION CONTINUES TO REMAIN SOUTH AND EAST OF OUR RIDGE
COUNTIES BUT SHOULD GRADUALLY EEK NORTHWESTWARD INTO
PRESTON/TUCKER/GARRETT OVERNIGHT. THE NEWEST NAM AND HRRR SEEM TO
LINE UP WELL WITH THE ONGOING PRECIP SHIELD SO WITH THIS IN MIND
AND A SLIGHTLY FASTER NORTHWARD PROGRESSION...HAVE MOVED PRECIP
TIMING UP JUST SLIGHTLY.
THE AFOREMENTIONED UPPER TROUGH WILL GRADUALLY WEAKEN AND DE-AMPLIFY
SUNDAY. WHILE FORCING SHOULD GENERALLY BE WEAK...THIS SHOULD LEAD TO
AT LEAST A SLIGHT CHANCE OF SHOWERS FURTHER NORTH AND WEST OF THE
WV/PA RIDGES AS THE DAY PROGRESSES. STILL THINK THAT THE BULK OF
THE REGION NORTH OF PITTSBURGH SHOULD REMAIN COMPLETELY DRY
SUNDAY.
WITH THICK CIRRUS ALREADY BLANKETING THE FORECAST
AREA...TEMPERATURES OVERNIGHT WHERE KEPT SLIGHTLY HIGHER THAN
PREVIOUSLY FORECAST. IN ADDITION...THE EXPANSE IN CLOUDS WILL KEEP
TEMPERATURES BELOW SEASONAL AVERAGES SUNDAY.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
UPR LOPRES OVER IN/KY WILL PHASE INTO BELT OF MDT WLYS OVER GRTLKS
RGN SUN NGT THRU MON. ALTHOUGH LIFT WILL DIMINISH THRU THIS TIME...
SHWRS XPCD TO FORM SUN NGT AND SPREAD ACRS MUCH OF THE FCST AREA
THRU MON. POPS WERE INCRD CNTRL/ERN ZONES.
POPS ALSO WERE DECRD MON NGT OWING TO RAPID PHASING AND DEPARTURE
OF THE WAVE AND INFLUENCE OF DVLPG SFC HIPRES IN ITS WAKE. A
SECOND SHRTWV TROF WILL APRCH THE RGN ON TUE...BUT LMTD MSTR WILL
LEAD TO WEAK INSTBY AND LKLY WILL SUPPRESS SHWR DVLPMT.
CLDS WILL LMT HEATING ON MON...WITH MAXIMA IN THE MID-UPR 70S
COMMON. BETTER HEATING XPCD ON TUE AS CLDS WILL BE LMTD TO DIURNAL
CU AMID TEMPS IN THE UPR 70S-LWR 80S.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
DRY WEATHER WILL CONTINUE FOR MUCH OF THE EXTENDED PERIOD AS HIGH
PRESSURE REMAINS ENTRENCHED OVER THE UPPER OHIO VALLEY.
MODELS FACING TIMING AND INTENSITY ISSUES WITH A SERIES OF FRONTAL
BOUNDARIES THAT WILL ATTEMPT TO CROSS THROUGH THE REGION TOWARD THE
END OF THE LONG TERM. BECAUSE OF UNCERTAINTY...WILL INCLUDE A
MENTION OF SCHC.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS ARE EXPECTED OVERNIGHT AND TOMORROW FOR MOST OF THE
TAF SITES WITH LITTLE MORE THAN HIGH CIRRUS EXPECTED. THE
EXCEPTIONS WILL BE ZZV...WHERE MVFR FOG COULD BE POSSIBLE IF SKIES
CLEAR OVERNIGHT...AND MGW IN SHOWERS TOMORROW AFTERNOON.
ELSEWHERE CLOUDS SHOULD THICKEN AND LOWER AS THE DAY PROGRESSES
BUT REMAIN VFR. SOUTHEASTERLY WINDS WILL CONTINUE TO REMAIN LIGHT.
.OUTLOOK.../SUNDAY THROUGH THURSDAY/...
INCRG CVRG OF SHWRS AND TSTMS MAY LEAD TO OCNL CIG/VSBY
RESTRICTIONS SUN NGT-MON. SFC HIPRES RETURNS BY MID-WK.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
956 PM EDT SAT AUG 17 2013
.SYNOPSIS...
LOW PRESSURE MOVES SLOWLY NORTHEAST ALONG THE MID ATLANTIC COAST
THIS WEEKEND. HIGH PRESSURE RETURNS MONDAY NIGHT THROUGH
WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
LATEST ANALYSIS SHOWED HI PRES CNTRD OVR NEW ENGLAND...WITH WEAK
LO PRES CNTRD JUST SW OF CAPE HATTERAS. CURRENT FCST IN GOOD
SHAPE...AS LATEST RDR INDICATED AREAS OF RAIN N OF THE LO WERE
SPREADING FARTHER NWRD INTO THE CWA. 00Z RUC IN GENERAL AGREEMENT
WITH THE GFS SHOWING THE WEAK LO PRES AREA MOVNG NE OVRNGT TO A
POSITION JUST E OF VA BEACH BY 12Z SUN. THIS WILL RESULT IN AREAS
OF RAIN SHIFTING INTO THE NRN HALF OF THE REGION LATER TNGT INTO
SUN MORNG. SO...WILL HAVE LIKELY TO CAT POPS EVERYWHERE. LO TEMPS
RANGING FM THE MID 60S TO ARND 70.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
LO LVL WEDGE TO HANG ON INTO SUN NGT. LO PRES CONTS TO TRACK NE
OFF THE VA/MD CST SUN...THEN NE AWAY FM THE RGN SUN NGT INTO MON.
RA ASSOCIATED W/ THAT LO TO MOVE OVR MNLY ERN PORTIONS OF THE FA
SUN MRNG BEFORE EXITING. MDLS SHOWING AREA OF RA TO PUSH NWD
THROUGH WRN HALF OF VA SUN/SUN NGT. MUCH OF THE FA BY SUN AFTN
THROUGH SUN NGT MAY BE LEFT W/ JUST CLDNS AND ONLY SPOTTY RA. BY
MON...TROUGH ALOFT APPROACHES FM THE W...CROSSING THE RGN LT MON
INTO MON NGT POSSIBLY ENHANCING TSTM PTNTL. ON TUE...SFC HI PRES
TAKES UP RESIDENCE INVOF CAROLINAS/FAR WRN ATLC...W/ WNW FLO
ALOFT. TSTM PTNTL ON TUE LWR ACRS ALL BUT FAR SRN VA/NE NC...W/
OVERALL WX CONDS RETURNING TO THOSE MORE TYPICAL OF AUG.
HI TEMPS SUN FM THE M70S NW TO L80S SE. LO TEMPS SUN NGT FM THE
M60S TO ARND 70F. HI TEMPS MON IN THE L/M80S. HI TEMPS TUE IN THE
M/U80S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
RATHER BENIGN WEATHER IN STORE AS A RATHER FLAT/ZONAL PATTERN
TAKES PLACE DURING THE MID TO LATE WORK WEEK TIMEFRAME. SURFACE
HIGH PRESSURE BECOMES CENTERED JUST SOUTH OF THE AREA ON WED/THU
AND PUSHES THE STALLED COASTAL BOUNDARY FARTHER SOUTH INTO THE
CAROLINAS. A FEW SPOKES OF MOISTURE COULD SNEAK UP INTO NE NC AND
POSSIBLY FAR SRN VA ON WEDNESDAY AND TOUCH OFF DIURNALLY-DRIVEN
AFTERNOON SHOWERS AND THUNDERSTORMS. FOR THURSDAY...A THERMAL
TROUGH DEVELOPS AND SHOULD HELP SHOWERS AND STORMS DEVELOP FURTHER
NORTH INTO CTRL VA THURSDAY AFTERNOON. A LOW PRESSURE SYSTEM
CROSSING THROUGH NEW ENGLAND IS THEN EXPECTED TO DRAG A FRONT
ACROSS THE REGION ON FRIDAY...FOCUSING BETTER PRECIP CHANCES ALONG
THIS BOUNDARY. BEHIND THE FRONT...HIGH PRESSURE RETURNS TO THE
AREA WITH DRIER AND SLIGHTLY COOLER TEMPS ANTICIPATED. HIGHS WILL
GENERALLY BE IN THE MID TO UPPER 80S AND LOWS IN THE 60S (LOWER
70S AT TIMES IN FAR SE VA/NE NC).
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
THE LATEST SURFACE ANALYSIS AND SATELLITE IMAGERY REVEALS A LOW
PRESSURE SYSTEM ALONG THE NORTH CAROLINA COAST TRACKING NE ALONG A
COASTAL FRONT. THE LOW IS PROGGED TO MOVE SLOWLY NE THROUGH
TONIGHT...BEFORE PULLING OFF TO THE NE SUNDAY. HAVE SOME LOW LEVEL
ISENTROPIC LIFT AS SHOWN ON THE VWP AND LOOKING AT THE RUC LAYER
FROM 925 MB TO 850 MB. THIS MOVES ACROSS NORTHEAST NORTH CAROLINA
AND SOUTHEAST VIRGINIA TONIGHT. TIMING AREAS OF SHOWERS WITH THIS
IS DIFFICULT BUT THE CURRENT RUC SEEMS TO HAVE A DECENT HANDLE ON
IT. WILL BRING IN SOME OF THE HEAVIER SHOWERS AND IFR CONDITIONS
INTO PHF ORF AND ECG BEFORE 03Z. WITH TIMING OF THE RAIN DIFFICULT
WILL SEE SOME TIMES WHERE THE CEILING RISES ABOVE IFR LEVELS. ALSO
WILL HAVE VSBY DOWN TO AROUND 1 MILE IN THE HEAVIER RAIN. IT LOOKS
LIKE THIS RAIN WILL MOVE NORTH OF THE AREA BY AROUND 10Z. FARTHER
WEST FOR RIC MAINLY ON THE EDGE OF THE PRECIPITATION WITH MORE TO
THE EAST AND THE WEST OF THE AREA. LOW CONFIDENCE IN EXACTLY HOW
CONDITIONS WILL EVOLVE TONIGHT AS ANY BATCH OF LIGHT PRECIPITATION
WILL LOWER CLOUDS SOME BUT FOR NOW THINK IT WILL NOT GO TO IFR FOR
THE NIGHT. FOR SBY BELIEVE THE PRECIPITATION WILL TAKE TILL WELL
PAST 06Z TO ARRIVE BUT THEN COULD SEE SOME BRIEF IFR CONDITIONS AS
THE LOW SLOWLY PULLS AWAY TO THE NORTHEAST. LOOKS LIKE BY SUNDAY
MOST THE STEADIER RAIN CONCENTRATES TO THE NORTH AND WEST OF THE
AREA SO SEE MAINLY MVFR TO VFR CONDITIONS PREVAILING.
STRATUS AND/OR FOG IS POSSIBLE MONDAY MORNING AS THERE IS LITTLE
CHANGE IN THE AMBIENT AIRMASS. A TROUGH SWINGS ACROSS THE AREA
MONDAY AFTERNOON PRODUCING A CHANCE OF SHOWERS AND TSTMS. CONDITIONS
IMPROVE THROUGH MIDWEEK.
&&
.MARINE...
A COASTAL LOW PRESSURE SYSTEM WILL PUSH NORTHEAST UP THE CAROLINA
COASTS AND INTO AREA WATERS TONIGHT AS IT TRAVELS ALONG A STALLED
BOUNDARY. THE COMBINATION OF A TIGHTENING SURFACE PRESSURE
GRADIENT AND COOL MARINE AIR MOVING OVER WARMER WATER TEMPS WILL
RESULT IN BREEZY AND PERSISTENT NE WINDS TONIGHT INTO SUNDAY
MORNING. A SURGE OF 15-20 KT WINDS THIS EVENING INTO SUNDAY
MORNING WILL INCREASE WAVES IN THE CHES BAY TO 4 FT (LOCALLY UP TO 5
FT NEAR THE MOUTH OF THE BAY)...AND INCREASE SEAS TWD 5 FT CLOSER
TO 20 NM FROM CAPE CHARLES LIGHT TO CURRITUCK LIGHT. SCA FLAGS
HAVE BEEN ISSUED FOR THE CHES BAY AND THE RIVERS AS WELL AS THE SRN
COASTAL WATERS THROUGH EARLY SUNDAY MORNING. AS THE COASTAL LOW
PUSHES NORTHEAST OVERNIGHT...THE TIGHTENED PRESSURE GRADIENT WILL
SHIFT NORTHEAST AND CAUSE WIND SPEEDS TO DIMINISH. AS THIS
OCCURS...SEAS WILL ALSO BEGIN TO SUBSIDE BELOW 5 FT JUST BEFORE
DAYBREAK. CHES BAY WILL BE SLOWER TO RESPOND TO SUBSIDING
CONDITIONS AND SCA FLAGS WILL PERSIST HERE THROUGH AT LEAST MID
MORNING BEFORE WINDS/WAVES TAPER OFF.
LOW PRESSURE CONTINUES ITS NORTHEAST TRACK DURING THE REST OF
SUNDAY AND AWAY FROM THE WATERS BY MONDAY MORNING. HIGH PRESSURE
RETURNS TO THE MID ATLANTIC REGION TUESDAY AND WEDNESDAY. FOR
SUNDAY...WINDS WILL CONTINUE TO BE N-NE AOB 15 KT NORTH AND
AOB 10 KT SOUTH. AFTER THAT...WINDS WILL GRADUALLY SHIFT AROUND TO
THE WEST AOB 10 KT WITH WAVES/SEAS AVERAGING 1-3 FT.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT SUNDAY FOR ANZ630>632-
634>636-638.
SMALL CRAFT ADVISORY UNTIL 8 AM EDT SUNDAY FOR ANZ656-658.
&&
$$
SYNOPSIS...ALB
NEAR TERM...ALB/TMG
SHORT TERM...ALB
LONG TERM...BMD
AVIATION...AJZ/JAB
MARINE...BMD/JAB
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
946 PM EDT SAT AUG 17 2013
.SYNOPSIS...
LOW PRESSURE MOVES SLOWLY NORTHEAST ALONG THE MID ATLANTIC COAST
THIS WEEKEND. HIGH PRESSURE RETURNS MONDAY NIGHT THROUGH
WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
LATEST ANALYSIS SHOWED HI PRES CNTRD OVR NEW ENGLAND...WITH WEAK
LO PRES CNTRD JUST SW OF CAPE HATTERAS. CURRENT FCST IN GOOD
SHAPE...AS LATEST RDR INDICATED AREAS OF RAIN N OF THE LO WERE
SPREADING FARTHER NWRD INTO THE CWA. 00Z RUC IN GENERAL AGREEMENT
WITH THE GFS SHOWING THE WEAK LO PRES AREA MOVNG NE OVRNGT TO A
POSITION JUST E OF VA BEACH BY 12Z SUN. THIS WILL RESULT IN AREAS
OF RAIN SHIFTING INTO THE NRN HALF OF THE REGION LATER TNGT INTO
SUN MORNG. SO...WILL HAVE LIKELY TO CAT POPS EVERYWHERE. LO TEMPS
RANGING FM THE MID 60S TO ARND 70.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
LO LVL WEDGE TO HANG ON INTO SUN NGT. LO PRES CONTS TO TRACK NE
OFF THE VA/MD CST SUN...THEN NE AWAY FM THE RGN SUN NGT INTO MON.
RA ASSOCIATED W/ THAT LO TO MOVE OVR MNLY ERN PORTIONS OF THE FA
SUN MRNG BEFORE EXITING. MDLS SHOWING AREA OF RA TO PUSH NWD
THROUGH WRN HALF OF VA SUN/SUN NGT. MUCH OF THE FA BY SUN AFTN
THROUGH SUN NGT MAY BE LEFT W/ JUST CLDNS AND ONLY SPOTTY RA. BY
MON...TROUGH ALOFT APPROACHES FM THE W...CROSSING THE RGN LT MON
INTO MON NGT POSSIBLY ENHANCING TSTM PTNTL. ON TUE...SFC HI PRES
TAKES UP RESIDENCE INVOF CAROLINAS/FAR WRN ATLC...W/ WNW FLO
ALOFT. TSTM PTNTL ON TUE LWR ACRS ALL BUT FAR SRN VA/NE NC...W/
OVERALL WX CONDS RETURNING TO THOSE MORE TYPICAL OF AUG.
HI TEMPS SUN FM THE M70S NW TO L80S SE. LO TEMPS SUN NGT FM THE
M60S TO ARND 70F. HI TEMPS MON IN THE L/M80S. HI TEMPS TUE IN THE
M/U80S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
RATHER BENIGN WEATHER IN STORE AS A RATHER FLAT/ZONAL PATTERN
TAKES PLACE DURING THE MID TO LATE WORK WEEK TIMEFRAME. SURFACE
HIGH PRESSURE BECOMES CENTERED JUST SOUTH OF THE AREA ON WED/THU
AND PUSHES THE STALLED COASTAL BOUNDARY FARTHER SOUTH INTO THE
CAROLINAS. A FEW SPOKES OF MOISTURE COULD SNEAK UP INTO NE NC AND
POSSIBLY FAR SRN VA ON WEDNESDAY AND TOUCH OFF DIURNALLY-DRIVEN
AFTERNOON SHOWERS AND THUNDERSTORMS. FOR THURSDAY...A THERMAL
TROUGH DEVELOPS AND SHOULD HELP SHOWERS AND STORMS DEVELOP FURTHER
NORTH INTO CTRL VA THURSDAY AFTERNOON. A LOW PRESSURE SYSTEM
CROSSING THROUGH NEW ENGLAND IS THEN EXPECTED TO DRAG A FRONT
ACROSS THE REGION ON FRIDAY...FOCUSING BETTER PRECIP CHANCES ALONG
THIS BOUNDARY. BEHIND THE FRONT...HIGH PRESSURE RETURNS TO THE
AREA WITH DRIER AND SLIGHTLY COOLER TEMPS ANTICIPATED. HIGHS WILL
GENERALLY BE IN THE MID TO UPPER 80S AND LOWS IN THE 60S (LOWER
70S AT TIMES IN FAR SE VA/NE NC).
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
THE LATEST SURFACE ANALYSIS AND SATELLITE IMAGERY REVEALS A LOW
PRESSURE SYSTEM ALONG THE NORTH CAROLINA COAST TRACKING NE ALONG A
COASTAL FRONT. THE LOW IS PROGGED TO MOVE SLOWLY NE THROUGH
TONIGHT...BEFORE PULLING OFF TO THE NE SUNDAY. HAVE SOME LOW LEVEL
ISENTROPIC LIFT AS SHOWN ON THE VWP AND LOOKING AT THE RUC LAYER
FROM 925 MB TO 850 MB. THIS MOVES ACROSS NORTHEAST NORTH CAROLINA
AND SOUTHEAST VIRGINIA TONIGHT. TIMING AREAS OF SHOWERS WITH THIS
IS DIFFICULT BUT THE CURRENT RUC SEEMS TO HAVE A DECENT HANDLE ON
IT. WILL BRING IN SOME OF THE HEAVIER SHOWERS AND IFR CONDITIONS
INTO PHF ORF AND ECG BEFORE 03Z. WITH TIMING OF THE RAIN DIFFICULT
WILL SEE SOME TIMES WHERE THE CEILING RISES ABOVE IFR LEVELS. ALSO
WILL HAVE VSBY DOWN TO AROUND 1 MILE IN THE HEAVIER RAIN. IT LOOKS
LIKE THIS RAIN WILL MOVE NORTH OF THE AREA BY AROUND 10Z. FARTHER
WEST FOR RIC MAINLY ON THE EDGE OF THE PRECIPITATION WITH MORE TO
THE EAST AND THE WEST OF THE AREA. LOW CONFIDENCE IN EXACTLY HOW
CONDITIONS WILL EVOLVE TONIGHT AS ANY BATCH OF LIGHT PRECIPITATION
WILL LOWER CLOUDS SOME BUT FOR NOW THINK IT WILL NOT GO TO IFR FOR
THE NIGHT. FOR SBY BELIEVE THE PRECIPITATION WILL TAKE TILL WELL
PAST 06Z TO ARRIVE BUT THEN COULD SEE SOME BRIEF IFR CONDITIONS AS
THE LOW SLOWLY PULLS AWAY TO THE NORTHEAST. LOOKS LIKE BY SUNDAY
MOST THE STEADIER RAIN CONCENTRATES TO THE NORTH AND WEST OF THE
AREA SO SEE MAINLY MVFR TO VFR CONDITIONS PREVAILING.
STRATUS AND/OR FOG IS POSSIBLE MONDAY MORNING AS THERE IS LITTLE
CHANGE IN THE AMBIENT AIRMASS. A TROUGH SWINGS ACROSS THE AREA
MONDAY AFTERNOON PRODUCING A CHANCE OF SHOWERS AND TSTMS. CONDITIONS
IMPROVE THROUGH MIDWEEK.
&&
.MARINE...
A COASTAL LOW PRESSURE SYSTEM WILL PUSH NORTHEAST UP THE CAROLINA
COASTS AND INTO AREA WATERS TONIGHT AS IT TRAVELS ALONG A STALLED
BOUNDARY. THE COMBINATION OF A TIGHTENING SURFACE PRESSURE
GRADIENT AND COOL MARINE AIR MOVING OVER WARMER WATER TEMPS WILL
RESULT IN BREEZY AND PERSISTENT NE WINDS TONIGHT INTO SUNDAY
MORNING. A SURGE OF 15-20 KT WINDS THIS EVENING INTO SUNDAY
MORNING WILL INCREASE WAVES IN SRN CHES BAY TO 4 FT (LOCALLY UP TO
5 FT NEAR THE MOUTH OF THE BAY)...AND INCREASE SEAS TWD 5 FT
CLOSER TO 20 NM FROM CAPE CHARLES LIGHT TO CURRITUCK LIGHT. SCA
FLAGS HAVE BEEN ISSUED FOR SRN CHES BAY AND SRN COASTAL WATERS
THROUGH EARLY SUNDAY MORNING. AS THE COASTAL LOW PUSHES NORTHEAST
OVERNIGHT...THE TIGHTENED PRESSURE GRADIENT WILL SHIFT NORTHEAST
AND CAUSE WIND SPEEDS TO DIMINISH. AS THIS OCCURS...SEAS WILL ALSO
BEGIN TO SUBSIDE BELOW 5 FT JUST BEFORE DAYBREAK. CHES BAY WILL BE
SLOWER TO RESPOND TO SUBSIDING CONDITIONS AND SCA FLAGS WILL
PERSIST HERE THROUGH AT LEAST MID MORNING BEFORE WINDS/WAVES
TAPER OFF.
LOW PRESSURE CONTINUES ITS NORTHEAST TRACK DURING THE REST OF
SUNDAY AND AWAY FROM THE WATERS BY MONDAY MORNING. HIGH PRESSURE
RETURNS TO THE MID ATLANTIC REGION TUESDAY AND WEDNESDAY. FOR
SUNDAY...WINDS WILL CONTINUE TO BE N-NE AOB 15 KT NORTH AND
AOB 10 KT SOUTH. AFTER THAT...WINDS WILL GRADUALLY SHIFT AROUND TO
THE WEST AOB 10 KT WITH WAVES/SEAS AVERAGING 1-3 FT.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT SUNDAY FOR ANZ656-658.
SMALL CRAFT ADVISORY UNTIL 10 AM EDT SUNDAY FOR ANZ632-634.
&&
$$
SYNOPSIS...ALB
NEAR TERM...ALB/TMG
SHORT TERM...ALB
LONG TERM...BMD
AVIATION...AJZ/JAB
MARINE...BMD/JAB
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
738 PM EDT SAT AUG 17 2013
.SYNOPSIS...
LOW PRESSURE MOVES SLOWLY NORTHEAST ALONG THE MID ATLANTIC COAST
THIS WEEKEND. HIGH PRESSURE RETURNS MONDAY THROUGH WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
SYNOPTIC SETUP MORE TYPICAL OF COOL SEASON THAN MID AUG...W/ SFC
HI PRES CENTERED INVOF NEW ENG...WEDGED SSW THROUGH THE MDATLC AND
TO GA/AL. CLDNS RMNS WIDESPREAD OVR THE FA THIS AFTN...AND THERE
HAS BEEN A GRADUAL LWRG OF CIGS...ESP ACRS SRN VA INTO NE NC. AS
FOR RA...THAT IS ANOTHER STORY. SPOTTY RA HAS MADE AN ATTEMPT TO
SPREAD N OF THE NC/VA BORDER THROUGH ERY AFTN...GENLY HAVING LMTD
SUCCESS. ANOTHER ATTEMPT AT RA SPREADING N FM THE CAROLINAS XPCD
TNGT...ESP AFT MID EVE. QPF FM THE MDLS SEEMS EXCESSIVE. ONE
AREA LIKELY TO BE CONCENTRATED CLOSE TO THE CST AS SFC LO PRES
DVLPS INVOF NC CST...AND RIBBON OF MOISTURE CONTS TO FEED NNW TWD
THE MTNS (AS UPR LVL LO PRES CIRCULATES INVOF LWR MS VLY). WILL
HAVE MSTLY HI CHC TO LIKELY POPS THROUGHOUT TNGT...LAST LOCATIONS
TO RECEIVE ANY RA WILL BE FAR NNE AREAS IN FA (ESP THE LWR MD ERN
SHR) AFT MDNGT. OTRW...CONTD LWRG OF CIGS FM S TO N OVRNGT.
CLIMO FAVORS ST OVR FG.
LO TEMPS FM THE M60S TO ARND 70F.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
LO LVL WEDGE TO HANG ON INTO SUN NGT. LO PRES CONTS TO TRACK NE
OFF THE VA/MD CST SUN...THEN NE AWAY FM THE RGN SUN NGT INTO MON.
RA ASSOCIATED W/ THAT LO TO MOVE OVR MNLY ERN PORTIONS OF THE FA
SUN MRNG BEFORE EXITING. MDLS SHOWING AREA OF RA TO PUSH NWD
THROUGH WRN HALF OF VA SUN/SUN NGT. MUCH OF THE FA BY SUN AFTN
THROUGH SUN NGT MAY BE LEFT W/ JUST CLDNS AND ONLY SPOTTY RA. BY
MON...TROUGH ALOFT APPROACHES FM THE W...CROSSING THE RGN LT MON
INTO MON NGT POSSIBLY ENHANCING TSTM PTNTL. ON TUE...SFC HI PRES
TAKES UP RESIDENCE INVOF CAROLINAS/FAR WRN ATLC...W/ WNW FLO
ALOFT. TSTM PTNTL ON TUE LWR ACRS ALL BUT FAR SRN VA/NE NC...W/
OVERALL WX CONDS RETURNING TO THOSE MORE TYPICAL OF AUG.
HI TEMPS SUN FM THE M70S NW TO L80S SE. LO TEMPS SUN NGT FM THE
M60S TO ARND 70F. HI TEMPS MON IN THE L/M80S. HI TEMPS TUE IN THE
M/U80S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
RATHER BENIGN WEATHER IN STORE AS A RATHER FLAT/ZONAL PATTERN
TAKES PLACE DURING THE MID TO LATE WORK WEEK TIMEFRAME. SURFACE
HIGH PRESSURE BECOMES CENTERED JUST SOUTH OF THE AREA ON WED/THU
AND PUSHES THE STALLED COASTAL BOUNDARY FARTHER SOUTH INTO THE
CAROLINAS. A FEW SPOKES OF MOISTURE COULD SNEAK UP INTO NE NC AND
POSSIBLY FAR SRN VA ON WEDNESDAY AND TOUCH OFF DIURNALLY-DRIVEN
AFTERNOON SHOWERS AND THUNDERSTORMS. FOR THURSDAY...A THERMAL
TROUGH DEVELOPS AND SHOULD HELP SHOWERS AND STORMS DEVELOP FURTHER
NORTH INTO CTRL VA THURSDAY AFTERNOON. A LOW PRESSURE SYSTEM
CROSSING THROUGH NEW ENGLAND IS THEN EXPECTED TO DRAG A FRONT
ACROSS THE REGION ON FRIDAY...FOCUSING BETTER PRECIP CHANCES ALONG
THIS BOUNDARY. BEHIND THE FRONT...HIGH PRESSURE RETURNS TO THE
AREA WITH DRIER AND SLIGHTLY COOLER TEMPS ANTICIPATED. HIGHS WILL
GENERALLY BE IN THE MID TO UPPER 80S AND LOWS IN THE 60S (LOWER
70S AT TIMES IN FAR SE VA/NE NC).
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
THE LATEST SURFACE ANALYSIS AND SATELLITE IMAGERY REVEALS A LOW
PRESSURE SYSTEM ALONG THE NORTH CAROLINA COAST TRACKING NE ALONG A
COASTAL FRONT. THE LOW IS PROGGED TO MOVE SLOWLY NE THROUGH
TONIGHT...BEFORE PULLING OFF TO THE NE SUNDAY. HAVE SOME LOW LEVEL
ISENTROPIC LIFT AS SHOWN ON THE VWP AND LOOKING AT THE RUC LAYER
FROM 925 MB TO 850 MB. THIS MOVES ACROSS NORTHEAST NORTH CAROLINA
AND SOUTHEAST VIRGINIA TONIGHT. TIMING AREAS OF SHOWERS WITH THIS
IS DIFFICULT BUT THE CURRENT RUC SEEMS TO HAVE A DECENT HANDLE ON
IT. WILL BRING IN SOME OF THE HEAVIER SHOWERS AND IFR CONDITIONS
INTO PHF ORF AND ECG BEFORE 03Z. WITH TIMING OF THE RAIN DIFFICULT
WILL SEE SOME TIMES WHERE THE CEILING RISES ABOVE IFR LEVELS. ALSO
WILL HAVE VSBY DOWN TO AROUND 1 MILE IN THE HEAVIER RAIN. IT LOOKS
LIKE THIS RAIN WILL MOVE NORTH OF THE AREA BY AROUND 10Z. FARTHER
WEST FOR RIC MAINLY ON THE EDGE OF THE PRECIPITATION WITH MORE TO
THE EAST AND THE WEST OF THE AREA. LOW CONFIDENCE IN EXACTLY HOW
CONDITIONS WILL EVOLVE TONIGHT AS ANY BATCH OF LIGHT PRECIPITATION
WILL LOWER CLOUDS SOME BUT FOR NOW THINK IT WILL NOT GO TO IFR FOR
THE NIGHT. FOR SBY BELIEVE THE PRECIPITATION WILL TAKE TILL WELL
PAST 06Z TO ARRIVE BUT THEN COULD SEE SOME BRIEF IFR CONDITIONS AS
THE LOW SLOWLY PULLS AWAY TO THE NORTHEAST. LOOKS LIKE BY SUNDAY
MOST THE STEADIER RAIN CONCENTRATES TO THE NORTH AND WEST OF THE
AREA SO SEE MAINLY MVFR TO VFR CONDITIONS PREVAILING.
STRATUS AND/OR FOG IS POSSIBLE MONDAY MORNING AS THERE IS LITTLE
CHANGE IN THE AMBIENT AIRMASS. A TROUGH SWINGS ACROSS THE AREA
MONDAY AFTERNOON PRODUCING A CHANCE OF SHOWERS AND TSTMS. CONDITIONS
IMPROVE THROUGH MIDWEEK.
&&
.MARINE...
A COASTAL LOW PRESSURE SYSTEM WILL PUSH NORTHEAST UP THE CAROLINA
COASTS AND INTO AREA WATERS TONIGHT AS IT TRAVELS ALONG A STALLED
BOUNDARY. THE COMBINATION OF A TIGHTENING SURFACE PRESSURE
GRADIENT AND COOL MARINE AIR MOVING OVER WARMER WATER TEMPS WILL
RESULT IN BREEZY AND PERSISTENT NE WINDS TONIGHT INTO SUNDAY
MORNING. A SURGE OF 15-20 KT WINDS THIS EVENING INTO SUNDAY
MORNING WILL INCREASE WAVES IN SRN CHES BAY TO 4 FT (LOCALLY UP TO
5 FT NEAR THE MOUTH OF THE BAY)...AND INCREASE SEAS TWD 5 FT
CLOSER TO 20 NM FROM CAPE CHARLES LIGHT TO CURRITUCK LIGHT. SCA
FLAGS HAVE BEEN ISSUED FOR SRN CHES BAY AND SRN COASTAL WATERS
THROUGH EARLY SUNDAY MORNING. AS THE COASTAL LOW PUSHES NORTHEAST
OVERNIGHT...THE TIGHTENED PRESSURE GRADIENT WILL SHIFT NORTHEAST
AND CAUSE WIND SPEEDS TO DIMINISH. AS THIS OCCURS...SEAS WILL ALSO
BEGIN TO SUBSIDE BELOW 5 FT JUST BEFORE DAYBREAK. CHES BAY WILL BE
SLOWER TO RESPOND TO SUBSIDING CONDITIONS AND SCA FLAGS WILL
PERSIST HERE THROUGH AT LEAST MID MORNING BEFORE WINDS/WAVES
TAPER OFF.
LOW PRESSURE CONTINUES ITS NORTHEAST TRACK DURING THE REST OF
SUNDAY AND AWAY FROM THE WATERS BY MONDAY MORNING. HIGH PRESSURE
RETURNS TO THE MID ATLANTIC REGION TUESDAY AND WEDNESDAY. FOR
SUNDAY...WINDS WILL CONTINUE TO BE N-NE AOB 15 KT NORTH AND
AOB 10 KT SOUTH. AFTER THAT...WINDS WILL GRADUALLY SHIFT AROUND TO
THE WEST AOB 10 KT WITH WAVES/SEAS AVERAGING 1-3 FT.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR
MDZ025.
NC...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR
NCZ102.
VA...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR
VAZ098>100.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT SUNDAY FOR ANZ632-634.
SMALL CRAFT ADVISORY UNTIL 4 AM EDT SUNDAY FOR ANZ656-658.
&&
$$
SYNOPSIS...ALB/MPR
NEAR TERM...ALB
SHORT TERM...ALB
LONG TERM...BMD
AVIATION...AJZ/JAB
MARINE...BMD
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
149 PM EDT FRI AUG 16 2013
.UPDATE...
ISSUED AT 922 AM EDT FRI AUG 16 2013
PESKY PATCH OF MID CLOUDS/ISOLD SHRA OVER SCNTRL LK SUPERIOR LED TO
UPDATE FOR CNTRL CWA FOR THE AFTN. SPC MESOANALYSIS SHOWS SHRA ARE
IN AREA OF H7 MOISTURE CONVERGENCE AND WEAK ELEVATED CAPE. WV LOOP
SHOWS A HINT OF A WAVE AS WELL. THAT FEATURE SHOULD REMAIN IN TACT
AS IT DRIFTS ACROSS ECNTRL UPR MICHIGAN /P53 TO ERY/ THIS AFTN. THIS
WILL ALSO MATCH UP WITH PEAK HEATING. CONVECTIVE TEMPS IN THE UPR
70S TO LOWER 80S SUGGEST EVEN WITH ADDITIONAL MOISTURE AND FORCING
THAT SHRA COVERAGE WILL REMAIN MINIMAL AND LATEST RAP SOUNDINGS
INDICATE DRY AIR BLO CLOUD BASE. PUT A MENTION OF SPRINKLES IN FROM
ALGER TO LUCE COUNTIES THIS AFTN AS CU DECK EXPANDS WITH ADDITIONAL
MOISTURE. ELSEWHERE CU SHOULD STAY CAPPED AND NUDGED MAX TEMPS UP A
FEW DEGREES BASED ON 12Z RAOBS FM INL/GRB. MOST AREAS OVER INTERIOR
WEST HALF OF CWA SHOULD SEE TEMPS TOP OUT AROUND 80 DEGREES.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 432 AM EDT FRI AUG 16 2013
BATTLING TEMPORARY VIS RESTRICTIONS AT A FEW OF THE SITES INLAND
FROM LAKE SUPERIOR THIS MORNING...AS IWD...IMT...ESC...AND ISQ JUMP
BETWEEN AROUND 1SM AND P6SM. HAVE KEPT PATCHY FOG GOING TO COVER
THIS...WITH A COUPLE POCKETS OF AREAS OF FOG NEAR THE LAKE MI
SHORELINE THROUGH DAYBREAK.
THE SFC RIDGE WILL REMAIN OVERHEAD...WITH THE HIGH STRENGTHENING
ACROSS THE NEW ENGLAND STATES THIS AFTERNOON THROUGH TONIGHT. LOW
PRESSURE WILL CONTINUE TO NEAR FROM THE W...WITH THE FIRST SFC LOW
ACROSS SASKATCHEWAN INTO N MANITOBA THIS MORNING SHIFTING E ABOUT
500MI BY 12Z SATURDAY /TO S MANITOBA AND S CENTRAL HUDSON BAY/.
WHILE THERE WILL BE WAA WITH 850MB TEMPS RISING FROM A CWA AVG OF
12C TO 13C BY THE END OF THE DAY IT WILL BE FAIRLY WEEK...AS NOTED
BY TRANSPORT WINDS OF 10KTS OR LESS OUT OF THE W TO SW...EVEN WITH
MIXING HEIGHTS OF 6-7.8KFT.
THE SW FLOW WILL PICK UP SLIGHT OVER W LAKE SUPERIOR OVERNIGHT
/AROUND 15KTS OR LESS/...WHILE REMAINING LIGHT OVER THE LAND.
CONTINUED TO GO AT OR BELOW GUIDANCE VALUES FOR OVERNIGHT LOWS GIVEN
OUR CLEAR SKY AND LIGHT WINDS...WITH UPPER 40S EXPECTED IN THE
TRADITIONAL COOL SPOTS WELL INLAND FROM THE GREAT LAKES.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 319 AM EDT FRI AUG 16 2013
MAIN FCST CONCERNS IN THE LONG TERM ARE TEMPS AND RELATIVELY SMALL
PCPN CHCS BEGINNING LATER ON SUN WITH PASSAGE OF DISTURBANCES IN
FAST W FLOW OVER SRN CANADA. ABOVE NORMAL HGTS ASSOCIATED WITH
SPRAWLING RDG OVER THE CONUS WL BRING ABV NORMAL TEMPS TO UPR MI
THIS WEEKEND AND NEXT WEEK.
SAT THRU SUN...CWA IS FCST TO BE DOMINATED BY DRY AIRMASS/ACYC WSW
FLOW ARND HI PRES CENTERED OVER THE NE CONUS. EXPECT MOCLR SKIES AND
A SLOW WARMING TREND WITH FCST H85 TEMPS 12-14C ON SAT AND THEN
14-16C ON SUN. STEADY SW WIND SHOULD HOLD MIN TEMPS UP ON SAT NGT...
ESPECIALLY IN THE DOWNSLOPE AREAS NEAR LK SUP FM IWD THRU THE
KEWEENAW TO BARAGA AND MQT.
SUN NGT/MON...LATEST LONGER RANGE GUIDANCE IN FAIRLY GOOD AGREEMENT
SHOWING A SHRTWV EMBEDDED IN THE WLY FLOW OVER SRN CANADA DIPPING
INTO THE UPR GRT LKS AND WEAKENING THE UPR RDG A BIT. THE GFS IS THE
MOST AGGRESSIVE MODEL TO WEAKEN THE RDG/GENERATE SHRA AND TS OVER
UPR MI. WL CARRY SOME LO CHC POPS OVER MAINLY THE NRN TIER OF THE
CWA CLOSER TO THE LOWER HGTS AND STNRY FNT FCST OVER SRN ONTARIO
JUST N OF LK SUP. MORE CLDS ARE LIKELY TO HOLD TEMPS UP A BIT MORE
ON SUN NGT BUT MAY CAUSE TEMPS TO RUN A BIT COOLER ON
MON...ESPECIALLY OVER THE NRN TIER.
EXTENDED...NOT SURPRISINGLY...EXTENDED MODEL GUIDANCE BEGINS TO SHOW
SOME DISAGREEMENT ON HOW MUCH THE UPR RDG WL BUILD BACK OVER THE UPR
LKS ON TUE FOLLOWING DEPARTURE OF SHRTWV RESPONSIBLE FOR SHRA/TS
POTENTIAL ON SUN NGT/MON AND THEN WHETHER/HOW QUICKLY MORE SHRTWVS
MIGHT IMPACT THE AREA AND FURTHER DEPRESS THE HIER HGTS OVER THE UPR
LKS AND TRY TO PUSH A STRONGER COLD FNT THRU UPR MI. CONSIDERING THE
LO PREDICTABILITY OF THESE DETAILS OF ZONAL FLOW REGIME IN THE
EXTENDED DURING SUMMER...FOLLOWED MODEL CONSENSUS FCST. OVERALL...
TEMPS SHOULD RUN ABV NORMAL...ESPECIALLY IF THE MODELS SHOWING THE
MORE PERSISTENT/STRONGER UPR RDG WITH NO FROPA THRU NEXT THU ARE
CORRECT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 148 PM EDT FRI AUG 16 2013
DAYTIME VFR CUMULUS CLOUDS AT KSAW AND KIWD THIS AFTN...BUT JUST
SOME MID CLOUDS AT TIMES FOR REST OF THE TAF PERIOD. LIGHT WINDS
WITH LAKE BREEZE DIRECTIONS THIS AFTN. EVENTUALLY A STEADY BUT LIGHT
SOUTHWEST WIND SETS UP ON SATURDAY BTWN A LOW PRESSURE TROUGH
MOVING ACROSS NORTHERN ONTARIO AND THE HIGH PRESSURE OVER THE LOWER
GREAT LAKES REGION.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 319 AM EDT FRI AUG 16 2013
OVERALL EXPECT WINDS LESS THAN 20 KTS THROUGH THE PERIOD AS HI
PRESSURE PERSISTS OVER THE GREAT LAKES REGION. THE ONE EXCEPTION
WILL BE SUN MORNING OVER THE NORTH CENTRAL...WHERE SW WINDS WILL
PEAK UP TO 25 KTS AHEAD OF A DISTURBANCE MOVING TOWARD THE UPPER
LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SHORT TERM...KF
LONG TERM...KC
AVIATION...JLA
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
924 AM EDT FRI AUG 16 2013
.UPDATE...
ISSUED AT 922 AM EDT FRI AUG 16 2013
PESKY PATCH OF MID CLOUDS/ISOLD SHRA OVER SCNTRL LK SUPERIOR LED TO
UPDATE FOR CNTRL CWA FOR THE AFTN. SPC MESOANALYSIS SHOWS SHRA ARE
IN AREA OF H7 MOISTURE CONVERGENCE AND WEAK ELEVATED CAPE. WV LOOP
SHOWS A HINT OF A WAVE AS WELL. THAT FEATURE SHOULD REMAIN IN TACT
AS IT DRIFTS ACROSS ECNTRL UPR MICHIGAN /P53 TO ERY/ THIS AFTN. THIS
WILL ALSO MATCH UP WITH PEAK HEATING. CONVECTIVE TEMPS IN THE UPR
70S TO LOWER 80S SUGGEST EVEN WITH ADDITIONAL MOISTURE AND FORCING
THAT SHRA COVERAGE WILL REMAIN MINIMAL AND LATEST RAP SOUNDINGS
INDICATE DRY AIR BLO CLOUD BASE. PUT A MENTION OF SPRINKLES IN FROM
ALGER TO LUCE COUNTIES THIS AFTN AS CU DECK EXPANDS WITH ADDITIONAL
MOISTURE. ELSEWHERE CU SHOULD STAY CAPPED AND NUDGED MAX TEMPS UP A
FEW DEGREES BASED ON 12Z RAOBS FM INL/GRB. MOST AREAS OVER INTERIOR
WEST HALF OF CWA SHOULD SEE TEMPS TOP OUT AROUND 80 DEGREES. &&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 432 AM EDT FRI AUG 16 2013
BATTLING TEMPORARY VIS RESTRICTIONS AT A FEW OF THE SITES INLAND
FROM LAKE SUPERIOR THIS MORNING...AS IWD...IMT...ESC...AND ISQ JUMP
BETWEEN AROUND 1SM AND P6SM. HAVE KEPT PATCHY FOG GOING TO COVER
THIS...WITH A COUPLE POCKETS OF AREAS OF FOG NEAR THE LAKE MI
SHORELINE THROUGH DAYBREAK.
THE SFC RIDGE WILL REMAIN OVERHEAD...WITH THE HIGH STRENGTHENING
ACROSS THE NEW ENGLAND STATES THIS AFTERNOON THROUGH TONIGHT. LOW
PRESSURE WILL CONTINUE TO NEAR FROM THE W...WITH THE FIRST SFC LOW
ACROSS SASKATCHEWAN INTO N MANITOBA THIS MORNING SHIFTING E ABOUT
500MI BY 12Z SATURDAY /TO S MANITOBA AND S CENTRAL HUDSON BAY/.
WHILE THERE WILL BE WAA WITH 850MB TEMPS RISING FROM A CWA AVG OF
12C TO 13C BY THE END OF THE DAY IT WILL BE FAIRLY WEEK...AS NOTED
BY TRANSPORT WINDS OF 10KTS OR LESS OUT OF THE W TO SW...EVEN WITH
MIXING HEIGHTS OF 6-7.8KFT.
THE SW FLOW WILL PICK UP SLIGHT OVER W LAKE SUPERIOR OVERNIGHT
/AROUND 15KTS OR LESS/...WHILE REMAINING LIGHT OVER THE LAND.
CONTINUED TO GO AT OR BELOW GUIDANCE VALUES FOR OVERNIGHT LOWS GIVEN
OUR CLEAR SKY AND LIGHT WINDS...WITH UPPER 40S EXPECTED IN THE
TRADITIONAL COOL SPOTS WELL INLAND FROM THE GREAT LAKES.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 319 AM EDT FRI AUG 16 2013
MAIN FCST CONCERNS IN THE LONG TERM ARE TEMPS AND RELATIVELY SMALL
PCPN CHCS BEGINNING LATER ON SUN WITH PASSAGE OF DISTURBANCES IN
FAST W FLOW OVER SRN CANADA. ABOVE NORMAL HGTS ASSOCIATED WITH
SPRAWLING RDG OVER THE CONUS WL BRING ABV NORMAL TEMPS TO UPR MI
THIS WEEKEND AND NEXT WEEK.
SAT THRU SUN...CWA IS FCST TO BE DOMINATED BY DRY AIRMASS/ACYC WSW
FLOW ARND HI PRES CENTERED OVER THE NE CONUS. EXPECT MOCLR SKIES AND
A SLOW WARMING TREND WITH FCST H85 TEMPS 12-14C ON SAT AND THEN
14-16C ON SUN. STEADY SW WIND SHOULD HOLD MIN TEMPS UP ON SAT NGT...
ESPECIALLY IN THE DOWNSLOPE AREAS NEAR LK SUP FM IWD THRU THE
KEWEENAW TO BARAGA AND MQT.
SUN NGT/MON...LATEST LONGER RANGE GUIDANCE IN FAIRLY GOOD AGREEMENT
SHOWING A SHRTWV EMBEDDED IN THE WLY FLOW OVER SRN CANADA DIPPING
INTO THE UPR GRT LKS AND WEAKENING THE UPR RDG A BIT. THE GFS IS THE
MOST AGGRESSIVE MODEL TO WEAKEN THE RDG/GENERATE SHRA AND TS OVER
UPR MI. WL CARRY SOME LO CHC POPS OVER MAINLY THE NRN TIER OF THE
CWA CLOSER TO THE LOWER HGTS AND STNRY FNT FCST OVER SRN ONTARIO
JUST N OF LK SUP. MORE CLDS ARE LIKELY TO HOLD TEMPS UP A BIT MORE
ON SUN NGT BUT MAY CAUSE TEMPS TO RUN A BIT COOLER ON
MON...ESPECIALLY OVER THE NRN TIER.
EXTENDED...NOT SURPRISINGLY...EXTENDED MODEL GUIDANCE BEGINS TO SHOW
SOME DISAGREEMENT ON HOW MUCH THE UPR RDG WL BUILD BACK OVER THE UPR
LKS ON TUE FOLLOWING DEPARTURE OF SHRTWV RESPONSIBLE FOR SHRA/TS
POTENTIAL ON SUN NGT/MON AND THEN WHETHER/HOW QUICKLY MORE SHRTWVS
MIGHT IMPACT THE AREA AND FURTHER DEPRESS THE HIER HGTS OVER THE UPR
LKS AND TRY TO PUSH A STRONGER COLD FNT THRU UPR MI. CONSIDERING THE
LO PREDICTABILITY OF THESE DETAILS OF ZONAL FLOW REGIME IN THE
EXTENDED DURING SUMMER...FOLLOWED MODEL CONSENSUS FCST. OVERALL...
TEMPS SHOULD RUN ABV NORMAL...ESPECIALLY IF THE MODELS SHOWING THE
MORE PERSISTENT/STRONGER UPR RDG WITH NO FROPA THRU NEXT THU ARE
CORRECT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 555 AM EDT FRI AUG 16 2013
OTHER THAN A FEW MID CLOUDS PASSING FROM TIME TO TIME...THE TAF
PERIOD WILL REMAIN FAIRLY CALM...WITH VFR CEILINGS AND VIS
ANTICIPATED. THERE IS A SMALL POTENTIAL FOR OCCASIONAL BR AGAIN AT
IWD AND TO A LESSER EXTENT SAW OVERNIGHT...BUT WILL KEEP IT OUT OF
THE FCST FOR NOW.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 319 AM EDT FRI AUG 16 2013
OVERALL EXPECT WINDS LESS THAN 20 KTS THROUGH THE PERIOD AS HI
PRESSURE PERSISTS OVER THE GREAT LAKES REGION. THE ONE EXCEPTION
WILL BE SUN MORNING OVER THE NORTH CENTRAL...WHERE SW WINDS WILL
PEAK UP TO 25 KTS AHEAD OF A DISTURBANCE MOVING TOWARD THE UPPER
LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SHORT TERM...KF
LONG TERM...KC
AVIATION...KF
MARINE...KC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1232 PM CDT FRI AUG 16 2013
.UPDATE...
ISSUED AT 501 AM CDT FRI AUG 16 2013
KUEX INDICATES SHOWER AND THUNDERSTORM ACTIVITY HAS DEVELOPED OVER
PORTIONS OF CENTRAL KANSAS...JUST SOUTH OF OUR CWA. RAP ANALYSIS
DATA INDICATES A SUBTLE MID LEVEL PERTURBATION IS ADVANCING SOUTH
FROM CENTRAL NEBRASKA INTO KANSAS...WITH WATER VAPOR IMAGERY ALSO
INDICATING A SUBTLE VORT MAX MOVING INTO KANSAS. BASED ON THE
POSITION OF THE SUBTLE VORT MAX ON WATER VAPOR IMAGERY...AND THE
POSITION OF THE MID LEVEL PERTURBATION FROM RAP ANALYSIS DATA...IT
APPEARS THE MID LEVEL TROUGH AXIS IS OVER OUR CWA NOW...WITH WEAK
MID LEVEL THERMAL ADVECTION AND DPVA AHEAD OF THIS TROUGH AXIS
LIKELY PROMOTING JUST ENOUGH OMEGA FOR PRECIPITATION PRODUCTION TO
OUR SOUTH. IN ADDITION TO THE MID LEVEL PERTURBATION...A SUBTLE
SURFACE TROUGH...PERHAPS A WEAK LOW LEVEL BAROCLINIC ZONE...IS
ALSO EVIDENT EXTENDING FROM WESTERN KANSAS INTO CENTRAL AND EAST-
CENTRAL KANSAS. RAP ANALYSIS SUGGESTS WEAK ISENTROPIC UPGLIDE IN
EXISTENCE ALONG/NEAR THE 295K SURFACE ACROSS THIS BOUNDARY...WITH
THE ONGOING SHOWER AND THUNDERSTORM ACTIVITY OCCURRING ALONG THIS
AXIS OF ISENTROPIC UPGLIDE. AT THIS TIME IT APPEARS THE WEAK MID
LEVEL OMEGA AND LOW LEVEL THERMAL ADVECTION RESPONSIBLE FOR THE
ONGOING PRECIPITATION PRODUCTION SHOULD REMAIN JUST SOUTH OF OUR
CWA...ALTHOUGH NOT BY MUCH...THUS ALLOWING FOR A CONTINUED DRY
FORECAST THROUGH THIS MORNING. THAT BEING SAID...THE ONGOING
SHOWER AND THUNDERSTORM ACTIVITY WILL NEED TO BE MONITORED TO MAKE
SURE IT DOES NOT SNEAK NORTHWARD INTO EXTREME SOUTHERN PORTIONS OF
OUR CWA.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 331 AM CDT FRI AUG 16 2013
OVERNIGHT MAP ANALYSIS INDICATES A LONGWAVE MID TO UPPER LEVEL
TROUGH IN EXISTENCE ACROSS THE EASTERN HALF OF THE CONUS...AND A
RIDGE OVER THE WEST. MID TO UPPER LEVEL JET ENERGY EXTENDS FROM
THE NORTHWESTERN CONUS...NORTHEAST INTO SOUTHWESTERN CANADA...THEN
SOUTHEAST ACROSS THE CENTRAL CONUS...AND FINALLY EAST AND
EVENTUALLY NORTHEAST ACROSS PORTIONS OF THE SOUTHEASTERN CONUS AND
EVENTUALLY THE EAST/NORTHEASTERN CONUS. MID TO UPPER LEVEL FLOW
OVER THE CENTRAL PLAINS REMAINS FROM THE 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. THE AFOREMENTIONED
MID LEVEL LONGWAVE RIDGE AND TROUGH CAN ALSO BE SEEN ON WATER
VAPOR IMAGERY...WITH INCREASED VALUES OF MID LEVEL MOISTURE ALSO
NOTED FLOWING ALONG THE AFOREMENTIONED JET AXIS. AT THE SURFACE A
SUBTLE TROUGH IS NOTED EXTENDING FROM WESTERN KANSAS INTO PORTIONS
OF NORTHEASTERN KANSAS. THE LOW LEVEL WIND FIELD ACROSS OUR AREA
REMAINS FROM THE EAST/NORTHEAST AS A RESULT.
GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...AND SREF-MEAN ALL
SUGGEST THE WESTERN CONUS LONGWAVE TROUGH WILL DRIFT EAST SOMEWHAT
THROUGH THE NEXT 24 HOURS. THE RESULTANT LACK IN OVERALL KINEMATIC
FORCING SUGGESTS DRY CONDITIONS SHOULD BE OBSERVED ACROSS OUR AREA
TODAY AND TONIGHT. THE ONLY OPPORTUNITY FOR MEASURABLE
PRECIPITATION MAY BE ACROSS OUR SOUTHWEST 06-12Z SATURDAY AS WEAK
LOW LEVEL THERMAL ADVECTION ALONG THE AXIS OF ~30KT 850MB JET AXIS
PROMOTES ISOLATED TO SCATTERED SHOWER AND THUNDERSTORM ACTIVITY
OVER THE CENTRAL HIGH PLAINS. THERE IS AN OUTSIDE CHANCE SOME OF
THIS ACTIVITY COULD CREEP INTO OUR FAR SOUTHWESTERN CWA BUT AT
THIS TIME CONFIDENCE IS NOT HIGH ENOUGH TO INSERT POPS INTO THE
SHORT TERM FORECAST PERIOD AND AS A RESULT...DRY CONDITIONS ARE
CURRENTLY FORECAST THROUGH 12Z SATURDAY.
ALTHOUGH CONFIDENCE WITH RESPECT TO MEASURABLE PRECIPITATION BEING
REALIZED ACROSS OUR CWA IS VERY LOW...CONFIDENCE WITH RESPECT TO
INCREASING CLOUD COVER ACROSS OUR AREA TONIGHT INTO EARLY SATURDAY
IS INCREASING. GUIDANCE FROM THE NAM AND OPERATIONAL GFS...AS WELL
AS THE MET AND MAV...SUGGEST THE AFOREMENTIONED LOW LEVEL THERMAL
ADVECTION ALONG THE AXIS OF THE LOW LEVEL JET STREAK SHOULD BE
STRONG ENOUGH TO PROVIDE ISENTROPIC UPGLIDE AND
SATURATION...PRIMARILY ALONG THE 300-305K SURFACES. GIVEN THESE
SOLUTIONS...WENT AHEAD AND INCREASED CLOUD COVER SIGNIFICANTLY
ACROSS MUCH OF OUR CWA TONIGHT INTO EARLY SATURDAY MORNING. IN
ADDITION TO THE STRATUS...NEAR-ZERO LOW LEVEL DEW POINT
DEPRESSIONS AND A LIGHT SOUTHEAST LOW LEVEL WIND FIELD COULD ALSO
PROMOTE FOG DEVELOPMENT ACROSS PORTIONS OF THE CWA TOWARDS
DAYBREAK SATURDAY. GIVEN THIS POTENTIAL...WENT AHEAD AND INSERTED
PATCHY FOG INTO THE GRIDS FOR EARLY SATURDAY MORNING.
PERSISTENT CLOUD COVER THROUGH MID TO LATE THIS MORNING...ALONG
WITH A PERSISTENT EASTERLY COMPONENT TO THE LOW LEVEL WIND
FIELD...WILL LIKELY KEEP TEMPERATURES ON THE COOL SIDE TODAY.
GUIDANCE FROM THE MET...MAV...AND ECS ALL SEEM TO HAVE A GOOD
HANDLE ON THIS AND TAKING AN EVEN-AVERAGE OF THESE THREE SETS OF
GUIDANCE PROVIDES AFTERNOON HIGHS IN THE MID 70S ACROSS THE
NORTHEASTERN TWO-THIRDS OF OUR CWA...AND CLOSER TO 80 ACROSS OUR
SOUTHWEST. LITTLE CHANGE IN THE LOW LEVEL AIRMASS AND INCREASING
CLOUD COVER...MUCH LIKE WE ARE OBSERVING THIS MORNING...SHOULD
PROVIDE SIMILAR OVERNIGHT LOW TEMPERATURES TONIGHT WHEN COMPARED
TO EARLY THIS MORNING. GIVEN THIS...WENT AHEAD WITH EARLY SATURDAY
MORNING TEMPERATURES NEAR 60 FOR MOST LOCATIONS ACROSS THE CWA.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 331 AM CDT FRI AUG 16 2013
A PATTERN CHANGE APPEARS TO BE ON THE WAY THAT WILL RESULT IN
DRIER WX AND TEMPS MORE TYPICAL OF SUMMER. THE MID-SUMMER BREAK
FOR A/C UNITS WILL END AS MULTIPLE DAYS OF 90F HEAT ARE IN THE
OFFING.
ALOFT: NOW THAT THE AK-CANADA HIGH LATITUDE BLOCKING IS FINALLY
BREAKING DOWN...THE FAIRLY HIGH AMPLITUDE ROCKIES RIDGE/ERN USA
TROF COMBO THAT HAS DOMINATED THE WX FOR THE PAST TWO WEEKS WILL
DE-AMPLIFY AS WELL. THE WESTERLIES WILL BECOME ZONAL AGAIN OVER
CANADA AND THE NRN USA. MEANWHILE...THE TROF OVER THE E PAC WILL
CLOSE OFF AND BECOME CUT-OFF...LINGERING OVER CA FOR THE NEXT
SEVERAL DAYS. THIS COMBINED WITH THE ERN USA TROF LIFTING OUT WILL
ALLOW THE SUBTROPICAL HIGH TO EXPAND ACROSS MOST OF THE CONUS. THE
WARMER TEMPS ALOFT SHOULD PUT A CAP ON PCPN POTENTIAL FOR SEVERAL
DAYS.
SFC: EXPANSIVE HIGH PRES THAT HAS BEEN PARKED OVER THE OH VALLEY
WILL GRADUALLY REPOSITION ITSELF OVER THE WRN ATLANTIC...BUT IT
WILL STILL EXTEND BACK INTO THE ERN USA. AS A SERIES OF LOWS
TRACKS ACROSS CANADA...A LEE-SIDE TROF WILL DEVELOP. THE INCREASED
PRES GRADIENT WILL RESULT IN A BIT MORE WIND THAN WE/VE SEEN FOR
THE LAST COUPLE WEEKS. THE NEXT COOL FRONTAL PASSAGE IS ADVERTISED
FOR NEXT THU AFTN-NGT.
THE 00Z EC AND GFS LOOK NOTHING ALIKE AT THE SFC AT 168 HRS /00Z
FRI/. THE GFS HAS A STRONGER SHRTWV TROF OVER THE PAC NW /H5 HGTS
40-60 M LOWER/ WHICH RESULTS IN A 997 MB LOW OVER ND VS. THE EC
1019 MB HIGH OVER LAKE WINNIPEG. THE 18Z GFS WAS MORE SUPPORTIVE
OF THE EC SOLUTION. SO THE 00Z RUN WAS NOT FACTORED INTO THIS FCST
BEYOND TUE.
THE DAILY DETAILS...
SAT: WIDESPREAD LOW STRATUS APPEARS LIKELY VIA MODEL CROSS
SECTIONS. SINCE IT/S CURRENTLY IN-PLACE AND THE FCST AREA WILL
REMAIN ON THE WRN FRINGE OF A SIZABLE POOL OF COOL AIR IN THE LOW-
LVLS...IT WILL BE HARD TO GET RID OFF UNTIL THE THERMAL TROF
RELEASES ITS GRIP WHICH WILL PROBABLY HAPPEN SUN.
SO EXPECT A CLOUDY START MOST AREAS WITH SLOW BUT GRADUAL
IMPROVEMENT. THERE WILL PROBABLY BE SOME AREAS THAT DON/T
COMPLETELY CLEAR OUT UNTIL MID-LATE AFTN. CAN FORESEE PARTS OF THE
FCST AREA NOT REACHING 80F.
SAT NGT: THE PRES GRADIENT WILL KEEP WINDS 7-15 MPH. SO DON/T
ENVISION FOG BEING A PROBLEM...BUT GIVEN THAT THE STRATUS/HIGH
LOW-LVL MSTR MAY NOT COMPLETELY MIX OUT SAT AFTN...LOW CLOUDS
SHOULD REFORM. JUST NOT SURE TO WHAT EXTENT.
SUN: THE DAY MAY START WITH STRATUS COVERING ALL OR PART OF THE
FCST AREA. FCST SOUNDINGS SUGGEST DRIER AIR WILL MIX DOWN. SO
IMPROVEMENT SHOULD BE MORE PERMANENT. SHOULD BE AN ESPECIALLY NICE
DAY FOR OUTDOOR ACTIVITIES BUT WITH S WINDS GUSTING UP TO 25 MPH.
MON-WED: SUNNY AND DRY AS WE SEE IT NOW. HIGH TEMPS WILL AVERAGE
ABOUT 5F WARMER THAN NORMAL.
THE NEXT OPPORTUNITY FOR TSTMS IS SLATED FOR THU AFTN-EVNG WITH A
COOL FRONTAL PASSAGE. WITH SUCH A WARM LOOK TO THE HGTS ALOFT...
CAPPING WILL PROBABLY LIMIT COVERAGE TO JUST AN ISOLATED TSTM OR
TWO.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1226 PM CDT FRI AUG 16 2013
QUIET CONDITIONS ARE FORECAST FOR THIS TAF PERIOD...WITH PRIMARY
FORECAST CONCERNS LYING WITH SKY COVER AND VISIBILITY...MAINLY
LATE TOMORROW NIGHT/EARLY TOMORROW MORNING. CONTINUING TO SEE
STUBBORN STRATUS AFFECTING THE TERMINAL AREA...WITH VISIBLE
SATELLITE SHOWING THE LAYER TRYING TO BREAK UP. THINKING THAT THE
TERMINAL WILL SEE AT LEAST SOME SUN THIS AFTERNOON...BUT TIMING IS
DIFFICULT SO KEPT MVFR CONDITIONS GOING FOR ANOTHER COUPLE HRS. A
RETURN OF THE MORE WIDESPREAD STRATUS DECK IS EXPECTED
TONIGHT...WITH ANOTHER CHANCE FOR DIMINISHED VISIBILITIES...WITH A
RETURN OF MVFR CONDITIONS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...BRYANT
SHORT TERM...BRYANT
LONG TERM...HALBLAUB
AVIATION...ADO
AREA FORECAST DISCUSSION
NWS HASTINGS NE
555 AM CDT FRI AUG 16 2013
.UPDATE...
ISSUED AT 501 AM CDT FRI AUG 16 2013
KUEX INDICATES SHOWER AND THUNDERSTORM ACTIVITY HAS DEVELOPED OVER
PORTIONS OF CENTRAL KANSAS...JUST SOUTH OF OUR CWA. RAP ANALYSIS
DATA INDICATES A SUBTLE MID LEVEL PERTURBATION IS ADVANCING SOUTH
FROM CENTRAL NEBRASKA INTO KANSAS...WITH WATER VAPOR IMAGERY ALSO
INDICATING A SUBTLE VORT MAX MOVING INTO KANSAS. BASED ON THE
POSITION OF THE SUBTLE VORT MAX ON WATER VAPOR IMAGERY...AND THE
POSITION OF THE MID LEVEL PERTURBATION FROM RAP ANALYSIS DATA...IT
APPEARS THE MID LEVEL TROUGH AXIS IS OVER OUR CWA NOW...WITH WEAK
MID LEVEL THERMAL ADVECTION AND DPVA AHEAD OF THIS TROUGH AXIS
LIKELY PROMOTING JUST ENOUGH OMEGA FOR PRECIPITATION PRODUCTION TO
OUR SOUTH. IN ADDITION TO THE MID LEVEL PERTURBATION...A SUBTLE
SURFACE TROUGH...PERHAPS A WEAK LOW LEVEL BAROCLINIC ZONE...IS
ALSO EVIDENT EXTENDING FROM WESTERN KANSAS INTO CENTRAL AND EAST-
CENTRAL KANSAS. RAP ANALYSIS SUGGESTS WEAK ISENTROPIC UPGLIDE IN
EXISTENCE ALONG/NEAR THE 295K SURFACE ACROSS THIS BOUNDARY...WITH
THE ONGOING SHOWER AND THUNDERSTORM ACTIVITY OCCURRING ALONG THIS
AXIS OF ISENTROPIC UPGLIDE. AT THIS TIME IT APPEARS THE WEAK MID
LEVEL OMEGA AND LOW LEVEL THERMAL ADVECTION RESPONSIBLE FOR THE
ONGOING PRECIPITATION PRODUCTION SHOULD REMAIN JUST SOUTH OF OUR
CWA...ALTHOUGH NOT BY MUCH...THUS ALLOWING FOR A CONTINUED DRY
FORECAST THROUGH THIS MORNING. THAT BEING SAID...THE ONGOING
SHOWER AND THUNDERSTORM ACTIVITY WILL NEED TO BE MONITORED TO MAKE
SURE IT DOES NOT SNEAK NORTHWARD INTO EXTREME SOUTHERN PORTIONS OF
OUR CWA.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 331 AM CDT FRI AUG 16 2013
OVERNIGHT MAP ANALYSIS INDICATES A LONGWAVE MID TO UPPER LEVEL
TROUGH IN EXISTENCE ACROSS THE EASTERN HALF OF THE CONUS...AND A
RIDGE OVER THE WEST. MID TO UPPER LEVEL JET ENERGY EXTENDS FROM
THE NORTHWESTERN CONUS...NORTHEAST INTO SOUTHWESTERN CANADA...THEN
SOUTHEAST ACROSS THE CENTRAL CONUS...AND FINALLY EAST AND
EVENTUALLY NORTHEAST ACROSS PORTIONS OF THE SOUTHEASTERN CONUS AND
EVENTUALLY THE EAST/NORTHEASTERN CONUS. MID TO UPPER LEVEL FLOW
OVER THE CENTRAL PLAINS REMAINS FROM THE 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. THE AFOREMENTIONED
MID LEVEL LONGWAVE RIDGE AND TROUGH CAN ALSO BE SEEN ON WATER
VAPOR IMAGERY...WITH INCREASED VALUES OF MID LEVEL MOISTURE ALSO
NOTED FLOWING ALONG THE AFOREMENTIONED JET AXIS. AT THE SURFACE A
SUBTLE TROUGH IS NOTED EXTENDING FROM WESTERN KANSAS INTO PORTIONS
OF NORTHEASTERN KANSAS. THE LOW LEVEL WIND FIELD ACROSS OUR AREA
REMAINS FROM THE EAST/NORTHEAST AS A RESULT.
GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...AND SREF-MEAN ALL
SUGGEST THE WESTERN CONUS LONGWAVE TROUGH WILL DRIFT EAST SOMEWHAT
THROUGH THE NEXT 24 HOURS. THE RESULTANT LACK IN OVERALL KINEMATIC
FORCING SUGGESTS DRY CONDITIONS SHOULD BE OBSERVED ACROSS OUR AREA
TODAY AND TONIGHT. THE ONLY OPPORTUNITY FOR MEASURABLE
PRECIPITATION MAY BE ACROSS OUR SOUTHWEST 06-12Z SATURDAY AS WEAK
LOW LEVEL THERMAL ADVECTION ALONG THE AXIS OF ~30KT 850MB JET AXIS
PROMOTES ISOLATED TO SCATTERED SHOWER AND THUNDERSTORM ACTIVITY
OVER THE CENTRAL HIGH PLAINS. THERE IS AN OUTSIDE CHANCE SOME OF
THIS ACTIVITY COULD CREEP INTO OUR FAR SOUTHWESTERN CWA BUT AT
THIS TIME CONFIDENCE IS NOT HIGH ENOUGH TO INSERT POPS INTO THE
SHORT TERM FORECAST PERIOD AND AS A RESULT...DRY CONDITIONS ARE
CURRENTLY FORECAST THROUGH 12Z SATURDAY.
ALTHOUGH CONFIDENCE WITH RESPECT TO MEASURABLE PRECIPITATION BEING
REALIZED ACROSS OUR CWA IS VERY LOW...CONFIDENCE WITH RESPECT TO
INCREASING CLOUD COVER ACROSS OUR AREA TONIGHT INTO EARLY SATURDAY
IS INCREASING. GUIDANCE FROM THE NAM AND OPERATIONAL GFS...AS WELL
AS THE MET AND MAV...SUGGEST THE AFOREMENTIONED LOW LEVEL THERMAL
ADVECTION ALONG THE AXIS OF THE LOW LEVEL JET STREAK SHOULD BE
STRONG ENOUGH TO PROVIDE ISENTROPIC UPGLIDE AND
SATURATION...PRIMARILY ALONG THE 300-305K SURFACES. GIVEN THESE
SOLUTIONS...WENT AHEAD AND INCREASED CLOUD COVER SIGNIFICANTLY
ACROSS MUCH OF OUR CWA TONIGHT INTO EARLY SATURDAY MORNING. IN
ADDITION TO THE STRATUS...NEAR-ZERO LOW LEVEL DEW POINT
DEPRESSIONS AND A LIGHT SOUTHEAST LOW LEVEL WIND FIELD COULD ALSO
PROMOTE FOG DEVELOPMENT ACROSS PORTIONS OF THE CWA TOWARDS
DAYBREAK SATURDAY. GIVEN THIS POTENTIAL...WENT AHEAD AND INSERTED
PATCHY FOG INTO THE GRIDS FOR EARLY SATURDAY MORNING.
PERSISTENT CLOUD COVER THROUGH MID TO LATE THIS MORNING...ALONG
WITH A PERSISTENT EASTERLY COMPONENT TO THE LOW LEVEL WIND
FIELD...WILL LIKELY KEEP TEMPERATURES ON THE COOL SIDE TODAY.
GUIDANCE FROM THE MET...MAV...AND ECS ALL SEEM TO HAVE A GOOD
HANDLE ON THIS AND TAKING AN EVEN-AVERAGE OF THESE THREE SETS OF
GUIDANCE PROVIDES AFTERNOON HIGHS IN THE MID 70S ACROSS THE
NORTHEASTERN TWO-THIRDS OF OUR CWA...AND CLOSER TO 80 ACROSS OUR
SOUTHWEST. LITTLE CHANGE IN THE LOW LEVEL AIRMASS AND INCREASING
CLOUD COVER...MUCH LIKE WE ARE OBSERVING THIS MORNING...SHOULD
PROVIDE SIMILAR OVERNIGHT LOW TEMPERATURES TONIGHT WHEN COMPARED
TO EARLY THIS MORNING. GIVEN THIS...WENT AHEAD WITH EARLY SATURDAY
MORNING TEMPERATURES NEAR 60 FOR MOST LOCATIONS ACROSS THE CWA.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 331 AM CDT FRI AUG 16 2013
A PATTERN CHANGE APPEARS TO BE ON THE WAY THAT WILL RESULT IN
DRIER WX AND TEMPS MORE TYPICAL OF SUMMER. THE MID-SUMMER BREAK
FOR A/C UNITS WILL END AS MULTIPLE DAYS OF 90F HEAT ARE IN THE
OFFING.
ALOFT: NOW THAT THE AK-CANADA HIGH LATITUDE BLOCKING IS FINALLY
BREAKING DOWN...THE FAIRLY HIGH AMPLITUDE ROCKIES RIDGE/ERN USA
TROF COMBO THAT HAS DOMINATED THE WX FOR THE PAST TWO WEEKS WILL
DE-AMPLIFY AS WELL. THE WESTERLIES WILL BECOME ZONAL AGAIN OVER
CANADA AND THE NRN USA. MEANWHILE...THE TROF OVER THE E PAC WILL
CLOSE OFF AND BECOME CUT-OFF...LINGERING OVER CA FOR THE NEXT
SEVERAL DAYS. THIS COMBINED WITH THE ERN USA TROF LIFTING OUT WILL
ALLOW THE SUBTROPICAL HIGH TO EXPAND ACROSS MOST OF THE CONUS. THE
WARMER TEMPS ALOFT SHOULD PUT A CAP ON PCPN POTENTIAL FOR SEVERAL
DAYS.
SFC: EXPANSIVE HIGH PRES THAT HAS BEEN PARKED OVER THE OH VALLEY
WILL GRADUALLY REPOSITION ITSELF OVER THE WRN ATLANTIC...BUT IT
WILL STILL EXTEND BACK INTO THE ERN USA. AS A SERIES OF LOWS
TRACKS ACROSS CANADA...A LEE-SIDE TROF WILL DEVELOP. THE INCREASED
PRES GRADIENT WILL RESULT IN A BIT MORE WIND THAN WE/VE SEEN FOR
THE LAST COUPLE WEEKS. THE NEXT COOL FRONTAL PASSAGE IS ADVERTISED
FOR NEXT THU AFTN-NGT.
THE 00Z EC AND GFS LOOK NOTHING ALIKE AT THE SFC AT 168 HRS /00Z
FRI/. THE GFS HAS A STRONGER SHRTWV TROF OVER THE PAC NW /H5 HGTS
40-60 M LOWER/ WHICH RESULTS IN A 997 MB LOW OVER ND VS. THE EC
1019 MB HIGH OVER LAKE WINNIPEG. THE 18Z GFS WAS MORE SUPPORTIVE
OF THE EC SOLUTION. SO THE 00Z RUN WAS NOT FACTORED INTO THIS FCST
BEYOND TUE.
THE DAILY DETAILS...
SAT: WIDESPREAD LOW STRATUS APPEARS LIKELY VIA MODEL CROSS
SECTIONS. SINCE IT/S CURRENTLY IN-PLACE AND THE FCST AREA WILL
REMAIN ON THE WRN FRINGE OF A SIZABLE POOL OF COOL AIR IN THE LOW-
LVLS...IT WILL BE HARD TO GET RID OFF UNTIL THE THERMAL TROF
RELEASES ITS GRIP WHICH WILL PROBABLY HAPPEN SUN.
SO EXPECT A CLOUDY START MOST AREAS WITH SLOW BUT GRADUAL
IMPROVEMENT. THERE WILL PROBABLY BE SOME AREAS THAT DON/T
COMPLETELY CLEAR OUT UNTIL MID-LATE AFTN. CAN FORESEE PARTS OF THE
FCST AREA NOT REACHING 80F.
SAT NGT: THE PRES GRADIENT WILL KEEP WINDS 7-15 MPH. SO DON/T
ENVISION FOG BEING A PROBLEM...BUT GIVEN THAT THE STRATUS/HIGH
LOW-LVL MSTR MAY NOT COMPLETELY MIX OUT SAT AFTN...LOW CLOUDS
SHOULD REFORM. JUST NOT SURE TO WHAT EXTENT.
SUN: THE DAY MAY START WITH STRATUS COVERING ALL OR PART OF THE
FCST AREA. FCST SOUNDINGS SUGGEST DRIER AIR WILL MIX DOWN. SO
IMPROVEMENT SHOULD BE MORE PERMANENT. SHOULD BE AN ESPECIALLY NICE
DAY FOR OUTDOOR ACTIVITIES BUT WITH S WINDS GUSTING UP TO 25 MPH.
MON-WED: SUNNY AND DRY AS WE SEE IT NOW. HIGH TEMPS WILL AVERAGE
ABOUT 5F WARMER THAN NORMAL.
THE NEXT OPPORTUNITY FOR TSTMS IS SLATED FOR THU AFTN-EVNG WITH A
COOL FRONTAL PASSAGE. WITH SUCH A WARM LOOK TO THE HGTS ALOFT...
CAPPING WILL PROBABLY LIMIT COVERAGE TO JUST AN ISOLATED TSTM OR
TWO.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 555 AM CDT FRI AUG 16 2013
IFR CONDITIONS FORECAST UNTIL 17Z...VFR CONDITIONS 17-05Z...AND
MVFR CONDITIONS TO FINISH THE TAF PERIOD.
STRATUS CONTINUES OVER MUCH OF SOUTH CENTRAL NEBRASKA WITH A
CEILING BETWEEN 500 AND 700FT AGL. PATCHY FOG WILL ALSO REMAIN
POSSIBLE ACROSS SOUTH CENTRAL NEBRASKA THROUGH MID MORNING...BUT
THE VISIBILITY AT GRI IS EXPECTED TO REMAIN GREATER THAN 6SM.
STRATUS IS EXPECTED TO BREAK APART AND LIFT BY LATE MORNING...THUS
THE VFR FORECAST STARTING 17Z. STRATUS IS THEN EXPECTED TO
REDEVELOP TONIGHT INTO SATURDAY MORNING...HOWEVER AT THIS TIME
THIS CEILING IS NOT EXPECTED TO DROP BELOW 1000FT AGL...SO FOR NOW
WILL GO WITH AN MVFR CEILING STARTING 05Z. GUIDANCE ALSO SUGGESTS
PATCHY FOG WILL BE POSSIBLE TOWARDS SUNRISE SATURDAY...WITH
VISIBILITY RESTRICTION PERHAPS APPROACHING 5SM. THE SURFACE WIND
WILL REMAIN LIGHT THROUGH THE TAF PERIOD...REMAINING FROM THE
EAST/SOUTHEAST FOR THE MOST PART.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...BRYANT
SHORT TERM...BRYANT
LONG TERM...HALBLAUB
AVIATION...BRYANT
AREA FORECAST DISCUSSION
NWS HASTINGS NE
501 AM CDT FRI AUG 16 2013
.UPDATE...
ISSUED AT 501 AM CDT FRI AUG 16 2013
KUEX INDICATES SHOWER AND THUNDERSTORM ACTIVITY HAS DEVELOPED OVER
PORTIONS OF CENTRAL KANSAS...JUST SOUTH OF OUR CWA. RAP ANALYSIS
DATA INDICATES A SUBTLE MID LEVEL PERTURBATION IS ADVANCING SOUTH
FROM CENTRAL NEBRASKA INTO KANSAS...WITH WATER VAPOR IMAGERY ALSO
INDICATING A SUBTLE VORT MAX MOVING INTO KANSAS. BASED ON THE
POSITION OF THE SUBTLE VORT MAX ON WATER VAPOR IMAGERY...AND THE
POSITION OF THE MID LEVEL PERTURBATION FROM RAP ANALYSIS DATA...IT
APPEARS THE MID LEVEL TROUGH AXIS IS OVER OUR CWA NOW...WITH WEAK
MID LEVEL THERMAL ADVECTION AND DPVA AHEAD OF THIS TROUGH AXIS
LIKELY PROMOTING JUST ENOUGH OMEGA FOR PRECIPITATION PRODUCTION TO
OUR SOUTH. IN ADDITION TO THE MID LEVEL PERTURBATION...A SUBTLE
SURFACE TROUGH...PERHAPS A WEAK LOW LEVEL BAROCLINIC ZONE...IS
ALSO EVIDENT EXTENDING FROM WESTERN KANSAS INTO CENTRAL AND EAST-
CENTRAL KANSAS. RAP ANALYSIS SUGGESTS WEAK ISENTROPIC UPGLIDE IN
EXISTENCE ALONG/NEAR THE 295K SURFACE ACROSS THIS BOUNDARY...WITH
THE ONGOING SHOWER AND THUNDERSTORM ACTIVITY OCCURRING ALONG THIS
AXIS OF ISENTROPIC UPGLIDE. AT THIS TIME IT APPEARS THE WEAK MID
LEVEL OMEGA AND LOW LEVEL THERMAL ADVECTION RESPONSIBLE FOR THE
ONGOING PRECIPITATION PRODUCTION SHOULD REMAIN JUST SOUTH OF OUR
CWA...ALTHOUGH NOT BY MUCH...THUS ALLOWING FOR A CONTINUED DRY
FORECAST THROUGH THIS MORNING. THAT BEING SAID...THE ONGOING
SHOWER AND THUNDERSTORM ACTIVITY WILL NEED TO BE MONITORED TO MAKE
SURE IT DOES NOT SNEAK NORTHWARD INTO EXTREME SOUTHERN PORTIONS OF
OUR CWA.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 331 AM CDT FRI AUG 16 2013
OVERNIGHT MAP ANALYSIS INDICATES A LONGWAVE MID TO UPPER LEVEL
TROUGH IN EXISTENCE ACROSS THE EASTERN HALF OF THE CONUS...AND A
RIDGE OVER THE WEST. MID TO UPPER LEVEL JET ENERGY EXTENDS FROM
THE NORTHWESTERN CONUS...NORTHEAST INTO SOUTHWESTERN CANADA...THEN
SOUTHEAST ACROSS THE CENTRAL CONUS...AND FINALLY EAST AND
EVENTUALLY NORTHEAST ACROSS PORTIONS OF THE SOUTHEASTERN CONUS AND
EVENTUALLY THE EAST/NORTHEASTERN CONUS. MID TO UPPER LEVEL FLOW
OVER THE CENTRAL PLAINS REMAINS FROM THE 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. THE AFOREMENTIONED
MID LEVEL LONGWAVE RIDGE AND TROUGH CAN ALSO BE SEEN ON WATER
VAPOR IMAGERY...WITH INCREASED VALUES OF MID LEVEL MOISTURE ALSO
NOTED FLOWING ALONG THE AFOREMENTIONED JET AXIS. AT THE SURFACE A
SUBTLE TROUGH IS NOTED EXTENDING FROM WESTERN KANSAS INTO PORTIONS
OF NORTHEASTERN KANSAS. THE LOW LEVEL WIND FIELD ACROSS OUR AREA
REMAINS FROM THE EAST/NORTHEAST AS A RESULT.
GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...AND SREF-MEAN ALL
SUGGEST THE WESTERN CONUS LONGWAVE TROUGH WILL DRIFT EAST SOMEWHAT
THROUGH THE NEXT 24 HOURS. THE RESULTANT LACK IN OVERALL KINEMATIC
FORCING SUGGESTS DRY CONDITIONS SHOULD BE OBSERVED ACROSS OUR AREA
TODAY AND TONIGHT. THE ONLY OPPORTUNITY FOR MEASURABLE
PRECIPITATION MAY BE ACROSS OUR SOUTHWEST 06-12Z SATURDAY AS WEAK
LOW LEVEL THERMAL ADVECTION ALONG THE AXIS OF ~30KT 850MB JET AXIS
PROMOTES ISOLATED TO SCATTERED SHOWER AND THUNDERSTORM ACTIVITY
OVER THE CENTRAL HIGH PLAINS. THERE IS AN OUTSIDE CHANCE SOME OF
THIS ACTIVITY COULD CREEP INTO OUR FAR SOUTHWESTERN CWA BUT AT
THIS TIME CONFIDENCE IS NOT HIGH ENOUGH TO INSERT POPS INTO THE
SHORT TERM FORECAST PERIOD AND AS A RESULT...DRY CONDITIONS ARE
CURRENTLY FORECAST THROUGH 12Z SATURDAY.
ALTHOUGH CONFIDENCE WITH RESPECT TO MEASURABLE PRECIPITATION BEING
REALIZED ACROSS OUR CWA IS VERY LOW...CONFIDENCE WITH RESPECT TO
INCREASING CLOUD COVER ACROSS OUR AREA TONIGHT INTO EARLY SATURDAY
IS INCREASING. GUIDANCE FROM THE NAM AND OPERATIONAL GFS...AS WELL
AS THE MET AND MAV...SUGGEST THE AFOREMENTIONED LOW LEVEL THERMAL
ADVECTION ALONG THE AXIS OF THE LOW LEVEL JET STREAK SHOULD BE
STRONG ENOUGH TO PROVIDE ISENTROPIC UPGLIDE AND
SATURATION...PRIMARILY ALONG THE 300-305K SURFACES. GIVEN THESE
SOLUTIONS...WENT AHEAD AND INCREASED CLOUD COVER SIGNIFICANTLY
ACROSS MUCH OF OUR CWA TONIGHT INTO EARLY SATURDAY MORNING. IN
ADDITION TO THE STRATUS...NEAR-ZERO LOW LEVEL DEW POINT
DEPRESSIONS AND A LIGHT SOUTHEAST LOW LEVEL WIND FIELD COULD ALSO
PROMOTE FOG DEVELOPMENT ACROSS PORTIONS OF THE CWA TOWARDS
DAYBREAK SATURDAY. GIVEN THIS POTENTIAL...WENT AHEAD AND INSERTED
PATCHY FOG INTO THE GRIDS FOR EARLY SATURDAY MORNING.
PERSISTENT CLOUD COVER THROUGH MID TO LATE THIS MORNING...ALONG
WITH A PERSISTENT EASTERLY COMPONENT TO THE LOW LEVEL WIND
FIELD...WILL LIKELY KEEP TEMPERATURES ON THE COOL SIDE TODAY.
GUIDANCE FROM THE MET...MAV...AND ECS ALL SEEM TO HAVE A GOOD
HANDLE ON THIS AND TAKING AN EVEN-AVERAGE OF THESE THREE SETS OF
GUIDANCE PROVIDES AFTERNOON HIGHS IN THE MID 70S ACROSS THE
NORTHEASTERN TWO-THIRDS OF OUR CWA...AND CLOSER TO 80 ACROSS OUR
SOUTHWEST. LITTLE CHANGE IN THE LOW LEVEL AIRMASS AND INCREASING
CLOUD COVER...MUCH LIKE WE ARE OBSERVING THIS MORNING...SHOULD
PROVIDE SIMILAR OVERNIGHT LOW TEMPERATURES TONIGHT WHEN COMPARED
TO EARLY THIS MORNING. GIVEN THIS...WENT AHEAD WITH EARLY SATURDAY
MORNING TEMPERATURES NEAR 60 FOR MOST LOCATIONS ACROSS THE CWA.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 331 AM CDT FRI AUG 16 2013
A PATTERN CHANGE APPEARS TO BE ON THE WAY THAT WILL RESULT IN
DRIER WX AND TEMPS MORE TYPICAL OF SUMMER. THE MID-SUMMER BREAK
FOR A/C UNITS WILL END AS MULTIPLE DAYS OF 90F HEAT ARE IN THE
OFFING.
ALOFT: NOW THAT THE AK-CANADA HIGH LATITUDE BLOCKING IS FINALLY
BREAKING DOWN...THE FAIRLY HIGH AMPLITUDE ROCKIES RIDGE/ERN USA
TROF COMBO THAT HAS DOMINATED THE WX FOR THE PAST TWO WEEKS WILL
DE-AMPLIFY AS WELL. THE WESTERLIES WILL BECOME ZONAL AGAIN OVER
CANADA AND THE NRN USA. MEANWHILE...THE TROF OVER THE E PAC WILL
CLOSE OFF AND BECOME CUT-OFF...LINGERING OVER CA FOR THE NEXT
SEVERAL DAYS. THIS COMBINED WITH THE ERN USA TROF LIFTING OUT WILL
ALLOW THE SUBTROPICAL HIGH TO EXPAND ACROSS MOST OF THE CONUS. THE
WARMER TEMPS ALOFT SHOULD PUT A CAP ON PCPN POTENTIAL FOR SEVERAL
DAYS.
SFC: EXPANSIVE HIGH PRES THAT HAS BEEN PARKED OVER THE OH VALLEY
WILL GRADUALLY REPOSITION ITSELF OVER THE WRN ATLANTIC...BUT IT
WILL STILL EXTEND BACK INTO THE ERN USA. AS A SERIES OF LOWS
TRACKS ACROSS CANADA...A LEE-SIDE TROF WILL DEVELOP. THE INCREASED
PRES GRADIENT WILL RESULT IN A BIT MORE WIND THAN WE/VE SEEN FOR
THE LAST COUPLE WEEKS. THE NEXT COOL FRONTAL PASSAGE IS ADVERTISED
FOR NEXT THU AFTN-NGT.
THE 00Z EC AND GFS LOOK NOTHING ALIKE AT THE SFC AT 168 HRS /00Z
FRI/. THE GFS HAS A STRONGER SHRTWV TROF OVER THE PAC NW /H5 HGTS
40-60 M LOWER/ WHICH RESULTS IN A 997 MB LOW OVER ND VS. THE EC
1019 MB HIGH OVER LAKE WINNIPEG. THE 18Z GFS WAS MORE SUPPORTIVE
OF THE EC SOLUTION. SO THE 00Z RUN WAS NOT FACTORED INTO THIS FCST
BEYOND TUE.
THE DAILY DETAILS...
SAT: WIDESPREAD LOW STRATUS APPEARS LIKELY VIA MODEL CROSS
SECTIONS. SINCE IT/S CURRENTLY IN-PLACE AND THE FCST AREA WILL
REMAIN ON THE WRN FRINGE OF A SIZABLE POOL OF COOL AIR IN THE LOW-
LVLS...IT WILL BE HARD TO GET RID OFF UNTIL THE THERMAL TROF
RELEASES ITS GRIP WHICH WILL PROBABLY HAPPEN SUN.
SO EXPECT A CLOUDY START MOST AREAS WITH SLOW BUT GRADUAL
IMPROVEMENT. THERE WILL PROBABLY BE SOME AREAS THAT DON/T
COMPLETELY CLEAR OUT UNTIL MID-LATE AFTN. CAN FORESEE PARTS OF THE
FCST AREA NOT REACHING 80F.
SAT NGT: THE PRES GRADIENT WILL KEEP WINDS 7-15 MPH. SO DON/T
ENVISION FOG BEING A PROBLEM...BUT GIVEN THAT THE STRATUS/HIGH
LOW-LVL MSTR MAY NOT COMPLETELY MIX OUT SAT AFTN...LOW CLOUDS
SHOULD REFORM. JUST NOT SURE TO WHAT EXTENT.
SUN: THE DAY MAY START WITH STRATUS COVERING ALL OR PART OF THE
FCST AREA. FCST SOUNDINGS SUGGEST DRIER AIR WILL MIX DOWN. SO
IMPROVEMENT SHOULD BE MORE PERMANENT. SHOULD BE AN ESPECIALLY NICE
DAY FOR OUTDOOR ACTIVITIES BUT WITH S WINDS GUSTING UP TO 25 MPH.
MON-WED: SUNNY AND DRY AS WE SEE IT NOW. HIGH TEMPS WILL AVERAGE
ABOUT 5F WARMER THAN NORMAL.
THE NEXT OPPORTUNITY FOR TSTMS IS SLATED FOR THU AFTN-EVNG WITH A
COOL FRONTAL PASSAGE. WITH SUCH A WARM LOOK TO THE HGTS ALOFT...
CAPPING WILL PROBABLY LIMIT COVERAGE TO JUST AN ISOLATED TSTM OR
TWO.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1253 AM CDT FRI AUG 16 2013
IFR CONDITIONS FORECAST UNTIL 15Z...VFR CONDITIONS 15-05Z...AND
MVFR CONDITIONS TO FINISH THE TAF PERIOD.
STRATUS HAS OVERTAKEN MUCH OF SOUTH CENTRAL NEBRASKA WITH A
CEILING BETWEEN 500 AND 700FT AGL BEING REPORTED THROUGH MANY
LOCATIONS. GUIDANCE SUGGESTS SUCH CEILINGS WILL BE OBSERVED AT GRI
THROUGH EARLY TO MID MORNING FRIDAY...THUS THE IFR FORECAST UNTIL
15Z. THERE MAY ALSO BE SOME VISIBILITY RESTRICTION IN FOG THROUGH
EARLY TO MID FRIDAY MORNING AS WELL...BUT AT THIS TIME IT IS
BELIEVED ANY VISIBILITY RESTRICTION WILL NOT DROP MUCH BELOW 5SM.
STRATUS IS EXPECTED TO BREAK APART AND LIFT BY EARLY TO MID
MORNING WITH VISIBILITY ALSO BEING FULLY RESTORED...THUS THE VFR
FORECAST STARTING 15Z. CONFIDENCE IS HIGH THAT VFR CONDITIONS WILL
BE REALIZED BY NO LATER THAN 15Z...BUT THIS WILL NEED TO BE
MONITORED THROUGH THE NEXT 10 OR SO HOURS. STRATUS IS CURRENTLY
EXPECTED TO REDEVELOP FRIDAY NIGHT INTO SATURDAY MORNING...HOWEVER
AT THIS TIME THIS CEILING IS NOT EXPECTED TO DROP BELOW 1000FT
AGL...SO FOR NOW WILL GO WITH MVFR CONDITIONS STARTING 05Z. THIS
WILL ALSO NEED TO BE CLOSELY MONITORED IN CASE IT BECOMES
INCREASINGLY EVIDENT CONDITIONS WILL DETERIORATE TO BELOW MVFR
LEVELS. THE SURFACE WIND WILL REMAIN LIGHT THROUGH THE TAF
PERIOD...REMAINING FROM THE EAST/SOUTHEAST FOR THE MOST PART.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...BRYANT
SHORT TERM...BRYANT
LONG TERM...HALBLAUB
AVIATION...BRYANT
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1238 AM CDT FRI AUG 16 2013
.SYNOPSIS...
ISSUED AT 333 PM CDT THU AUG 15 2013
CURRENTLY...AN UPPER LEVEL DISTURBANCE IS MOVING SOUTH-SOUTHEAST
ACROSS SOUTH DAKOTA IN NORTHWEST FLOW ALOFT. AN UPPER LEVEL RIDGE
EXTENDS NORTHWARD FROM THE FOUR CORNERS REGION TO SASKATCHEWAN AND
AN UPPER LEVEL LOW EXISTS OVER QUEBEC. A SURFACE BOUNDARY
CURRENTLY EXTENDS NORTHWESTWARD FROM FRONTIER COUNTY THROUGH
GARDEN COUNTY AND INTO NORTHWESTERN NEBRASKA. ALSO...LOW CLOUDS
HAVE BEEN PERSISTENT OVER PARTS OF NORTH-CENTRAL NEBRASKA TODAY.
&&
.UPDATE...
ISSUED AT 932 PM CDT THU AUG 15 2013
UPDATED TO REMOVE REMAINING PRECIP CHANCES AND TO FINE TUNE
AREAS/PATCHY FOG GRIDS. OTHERWISE REMAINDER OF THE FCST LOOKS GOOD.
UPDATE ISSUED AT 654 PM CDT THU AUG 15 2013
HAVE UPDATED TO REMOVE PRECIPITATION CHANCES FOR ALL BUT THE FAR
SOUTHERN PORTION OF THE FCST AREA THIS EVENING BASED ON LATEST
SATELLITE/RADAR TRENDS AND GUIDANCE FROM SHORT RANGE MODELS. THE
BIGGEST FCST CHALLENGE TONIGHT WILL BE TIMING THE ONSET OF FOG
ALONG AND EAST OF THE HIGHWAY 83 CORRIDOR. SOME VISIBILITIY
RESTRICTIONS ALREADY ALONG THE HIGHWAY 281 CORRIDOR IN HOLT COUNTY
BASED ON OBS AND WEB CAMS. WHILE THERE MAY BE SOME DECREASE IN
CLOUDS BRIEFLY IN THE NORTH CENTRAL ARAS...EXPECT THEM TO COME
BACK IN LATE THIS EVENING AND DURING THE EARLY MORNING HOURS AS
THE FCST AREA EXPERIENCES INCREASING SUBSIDENCE FROM EXITING UPPER
PV ANOMALY WHILE MOIST BUT LIGHT UPSLOPE FLOW CONTINUES. PREVIOUS
FCST HAD THIS ALERADY...BUT HAVE MOVED UP THE TIMING A BIT IN THE
EASTERN PORTION OF THE FCST AREA.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 333 PM CDT THU AUG 15 2013
STARTING TO SEE SOME CUMULUS DEVELOPMENT ALONG STATIONARY SURFACE
BOUNDARY EXTENDING TO THE NW FROM FRONTIER COUNTY THROUGH OGALLALA
AND NWWD. BELIEVE THIS WOULD BE THE BEST AREA FOR THUNDERSTORM
DEVELOPMENT THIS AFTERNOON...WITH ANY STORMS MOVING SOUTHEASTWARD
AT AROUND 20 KTS. MODELS INDICATE 0-6 KM SHEAR OF 30-35 KTS
ALTHOUGH SPC MESOANALYSIS DATA IS SHOWING SHEAR UNDER 30 KTS AS OF
20Z. THERE MAY BE A FEW ISOLATED SEVERE STORMS THIS AFTN/EVE...BUT
THE BEST CHANCE WOULD BE SOUTH OF I-80. HAVE TRIMMED POPS AND
THUNDERSTORM COVERAGE A BIT ACROSS THE AREA TONIGHT BASED ON
LATEST MODEL DATA AND TRENDS. HRRR MODEL FROM 18Z HAS A FEW STORMS
JUST WEST OF NORTH PLATTE AND AREAS SE...MOVING SE TONIGHT. EMC
WRF MODEL HAS A FAIR AMOUNT OF CONVECTION NORTH TO THE SD BORDER
HOWEVER...ALTHOUGH ITS NOT AS LIKELY. THUNDERSTORMS SHOULD COME TO
AN END IN THE EVENING ACROSS THE AREA AS THE UPPER LEVEL WAVE
MOVES THROUGH THE REGION. MODELS ARE POINTING TOWARD MORE FOG AND
LOW STRATUS TONIGHT...ESPECIALLY CENTRAL AND EAST. HAVE INCLUDED
FOG IN THE FORECAST FOR MOST OF THE AREA. TOMORROW...AFTER LOW
CLOUDS AND FOG HAVE DISSIPATED...FAIR SKIES AND TEMPS IN THE MID
70S EAST TO UPPER 80S WEST ARE EXPECTED.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 333 PM CDT THU AUG 15 2013
MID TERM...FRIDAY NIGHT THROUGH SUNDAY...RIDGING WILL CONTINUE TO
BUILD ACROSS THE CENTRAL PLAINS FRIDAY NIGHT THROUGH SATURDAY
NIGHT...WITH TEMPERATURES THE MAIN FORECAST CHALLENGE...FOLLOWED BY
PRECIPITATION CHANCES IN THE FAR WEST SUNDAY AFTERNOON. FOR FRIDAY
NIGHT...SURFACE HIGH PRESSURE WILL DRIFT EAST INTO THE MIDDLE
MISSISSIPPI VALLEY WITH A LEE SIDE TROUGH BEGINNING TO DEEPEN ACROSS THE
FRONT RANGES OF COLORADO AND WYOMING. SRLY WINDS WILL BEGIN TO
INCREASE LATE FRIDAY IN RESPONSE...AND ARE NOT EXPECTED TO TOTALLY
DECOUPLE FRIDAY NIGHT. THIS WILL LEAD TO SLIGHTLY WARMER MIN TEMPS
SATURDAY MORNING COMPARED TO FRIDAY MORNING. THE MET AND MAV
GUIDANCE ARE IN DECENT AGREEMENT WITH LOWS SATURDAY MORNING SO A
BLEND WILL BE UTILIZED...THEN SCALED UPWARD A DEGREE OR TWO DUE TO
INCREASED MIXING. MAV AND MET GUIDANCE TEMPS DIVERGE ON
SATURDAY...WITH THE MAV 3 TO 6 DEGREES COOLER THAN THE MUCH WARMER
MET. UTILIZED THE BIAS CORRECTED CONSALL GUIDANCE FOR HIGHS
SATURDAY...WHICH RESULTED IN A COMPROMISE BETWEEN THE MET AND MAV
NUMBERS. THIS LED TO HIGHS IN THE MIDDLE 80S IN THE EASTERN CWA...TO
THE LOWER 90S IN THE PANHANDLE...WHERE DEW POINTS IN THE LOWER 50S
ARE EXPECTED SAT AFTERNOON. FOR SUNDAY...HIGHS WILL MIRROR SATURDAYS
FCST...WITH THE EXCEPTION OF THE EASTERN ZONES WHERE SLIGHTLY WARMER
TEMPS ARE EXPECTED THANKS TO WARMER H85 AIR. HIGHS SUNDAY WILL RANGE
FROM THE UPPER 80S TO LOWER 90S IN THE PANHANDLE AND FAR WEST. BY
SUNDAY AFTERNOON...THE LATEST NAM IS HINTING AT BREAKING DOWN THE
RIDGE AND INITIATING CONVECTION ACROSS THE PANHANDLE AND FAR WESTERN
ZONES LATE SUNDAY AFTERNOON. THE LATEST GFS...KEEPS THIS CONVECTION
CONFINED TO THE FRONT RANGES OF COLORADO AND WYOMING...THANKS TO
VERY WEAK MID LEVEL STEERING WINDS. INHERITED FCST WAS DRY SUNDAY
AFTERNOON...AND INTEND TO KEEP IT THAT WAY...EVEN IN LIGHT OF THE
LATEST 12Z NAM SOLN.
LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...THERE ARE TWO SCHOOLS
OF THOUGHT WITH THE EXTENDED FCST...A...DRY AND VERY WARM CONDS
WILL PERSIST WELL INTO THE MIDDLE OF NEXT WEEK-12Z GFS...AND B...A
BREAK DOWN IN THE RIDGE ACROSS THE CENTRAL CONUS LEADING TO COOLER
AND WETTER CONDS ACROSS THE AREA-ECMWF. GLANCING AT LAST NIGHTS
ENSEMBLES...THE MEAN NCEP ENSEMBLE MEAN HAS A BREAKDOWN IN THE
WESTERN CONUS RIDGING EARLY IN THE WEEK WITH A FAIRLY ACTIVE
PATTERN DEVELOPING BY MIDWEEK. IN CONTRAST...THE OPERATIONAL GFS
FROM THIS MORNING HAS A CLOSED LOW OVER THE CENTRAL CA COAST. THE
LATTER SOLN...WOULD TEND TO FAVOR A DRY AND WARMER FCST AS RIDGING
WILL AMPLIFY DOWNSTREAM OF THE CLOSED CA LOW. NO SURPRISE...THE
LATEST MEX GUIDANCE FROM THIS MORNING HAS LOWER TO MIDDLE 90S FOR
HIGHS NEXT WEEK WITH DRY CONDS EXPECTED. SINCE THE OPERATIONAL GFS
IS KIND OF AN OUTLIER WITH THE ENSEMBLE FCSTS...WILL FAVOR COOLER
TEMPS IN THE 80S TO LOWER 90S FOR TEMPS NEXT WEEK. AS FOR PCPN
CHANCES...CAN`T SEE MORE THAN A 20 PCT CHANCE TOWARD THE MIDDLE OF
NEXT WEEK...AS WEAK DYNAMICS WILL CONTINUE WELL INTO NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1237 AM CDT FRI AUG 16 2013
MAIN AVIATION FCST CHALLENGE WILL BE GEOGRAPHICAL EXTENT AND
DURATION OF FOG/LOW CLOUDS INTO THE MORNING HOURS. KONL IS DOWN TO
AROUND 1/2SM FOR THE LAST HOUR. CIGS AT KONL...KANW AND KTIF IN THE
LIFR RANGE. FURTHER SOUTH KLBF NOW DOWN TO 4SM. FCST WILL FOLLOW
THE IDEA THAT LOWEST VSBYS /1SM RANGE AND BELOW/ WOULD OCCUR ON
THE WESTERN FRINGE OF STRATUS AS IS TYPICALLY THE CASE.
TIMING OF LOW CLOUD/FOG BURNOFF ALWAYS TOUGH THIS TIME OF YEAR WITH
MINIMAL MECHANICAL MIXING OCCURRING INITIALLY. WILL GO FOR A LATE
MORNING RETURN TO VFR CONDITIONS.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JWS
SYNOPSIS...KNUTSVIG
SHORT TERM...KNUTSVIG
LONG TERM...CLB
AVIATION...ROBERG
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1025 PM EDT SAT AUG 17 2013
.SYNOPSIS...
LOW PRESSURE WILL EXIT NE OF THE AREA THIS EVENING...AND OFF THE
OUTER BANKS BY DAYBREAK SUNDAY. A FRONTAL SYSTEM DRAPED ALONG THE
IMMEDIATE COAST OF THE CAROLINAS AND HIGH PRESSURE RIDGING
SOUTHWEST ACROSS THE CENTRAL CAROLINAS...WILL BOTH PERSIST INTO
EARLY NEXT WEEK. THE FRONT WILL FINALLY DISSIPATE BY MIDWEEK WITH
WEAK HIGH PRESSURE REMAINING ACROSS THE AREA. THE CHANCE FOR
CONVECTION WILL EXIST EACH AFTERNOON AND EVENING THROUGH THE MID
WEEK PERIOD OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
AS OF 1000 PM SATURDAY...MODELS...HAVING A PROBLEM WITH THE
CLUSTER OF SHOWERS AND STORMS JUST WEST OF THE GA-SC BORDER. HRRR
SEEMS TO HAVE CAUGHT ON SOMEWHAT...THE GFS SHOWS A VERY WEAK S/W
TROF OR IMPULSE ALOFT AS A POSSIBLE CAUSE...AND THE NAM INDICATES
SUBSIDENCE FOR THE REST OF TONIGHT. SREF CONTINUES TO ILLUSTRATE
VERY LITTLE IN THE PROBABILITY OF MEASURE-ABLE RAINFALL EAST OF THE
I-95 CORRIDOR TO THE CAROLINA COASTS. WILL STICK WITH THE HRRR
OUTPUT...AND RAISE CHANCE POPS ALONG THE IMMEDIATE COAST AFTER 06Z
FOR THE SOUTHERN COASTAL ZONES. WILL THEN FOLLOW THE HRRR AND
INDICATE POPS ALONG THE COAST REACHING THE NC-SC COASTAL BORDER
AFTER DAYBREAK SUN. TONIGHTS WX MAP/FEATURES RESEMBLES WHAT ONE
WOULD OBSERVE DURING THE LATE FALL THROUGH EARLY SPRING MONTHS.
IE. SFC HIGH NOSING/RIDGING FROM THE NE STATES AND A COASTAL
TROF/FRONT ALONG THE IMMEDIATE COAST. DO NOT EXPECT THE COASTAL
FRONT/TROF TO MOVE ONSHORE OVERNIGHT DUE TO THE CORRELATION WITH
SFC AND UPPER TROFFINESS NOT PRESENT ACROSS TX/OK. AS FOR
TONIGHT...A NEARLY SATURATED ATM TO EXIST WITH PWS 2+ INCHES. THE
SFC BASED INSTABILITY HOWEVER... WILL BE LACKING VIA LATEST HRRR
RUNS AND VARIOUS PROGGED NAMBUFR SOUNDINGS ACROSS THE FA. THE
LATEST SREF PROBABILITY OF MEASURE-ABLE PCPN INDICATES THE BEST
PROBS WILL OCCUR FROM ACROSS THE LEE-SIDE OF THE APPALACHIANS TO
WEST OF I-95. WILL CONTINUE TO OUTLINE ALONG OR WEST OF THE I-95
CORRIDOR FOR PCPN POPS. AS FOR MIN TEMPS...SLIGHTLY TWEAKED THE
IMMEDIATE COASTAL COUNTIES UPWARDS DUE TO THE CLOSE PROXIMITY TO
THE 80 DEGREE SSTS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...THE OLD FRONT WILL REMAIN ACROSS THE AREA
THROUGH THE PERIOD. AN UPPER LOW TO THE WEST WILL MAINTAIN SW FLOW
ALOFT SUNDAY BUT HIGH PRESSURE RIDGING IN FROM THE EAST WILL SHIFT
THE BEST LIFT AND DEEP MOISTURE TO THE WEST AND NORTH OF THE FA.
MAIN FOCUS FOR PRECIP SUNDAY WILL BE THE FRONT AND DIURNAL HEATING
SO FORECAST HAS CHANCE POPS FOR THE AFTERNOON AND EVENING HOURS AND
SLIGHT CHANCE IN THE MORNING AND OVERNIGHT SUNDAY INTO MONDAY
MORNING. MAXIMUMS SUNDAY WILL BE WARMER AND SHOULD REACH THE LOW TO
MID 80S UNDER PARTLY TO MOSTLY CLOUDY.
ON MONDAY...THE UPPER LOW TO THE WEST WILL EJECT NORTHEASTWARD AND
BRING UPPER SUPPORT FOR PRECIPITATION TO THE AREA AGAIN WITH THE
FRONT IN THE AREA. THE FORECAST WILL HAVE SLIGHTLY HIGHER CHANCE
POPS FOR MONDAY THAN SUNDAY...AGAIN FOCUSING ON THE PRIME DIURNAL
PERIOD FOR CONVECTION. MAXIMUMS MONDAY SHOULD REACH THE MID TO
UPPER 80S UNDER PARTLY TO MOSTLY CLOUDY SKIES. MINS SUNDAY NIGHT
AND MONDAY NIGHT SHOULD BE WITHIN A COUPLE DEGREES OF 70.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 3 PM SATURDAY...THE 500 MB UPPER LEVEL RIDGE AXIS TRIES TO
BUILD WESTWARD AND WILL ALIGNED ALONG A LINE FROM MOBILE TO
SAVANNAH AND OUR REGION WILL BE ON THE SOUTHERN FRINGES OF THE
NORTHWEST FLOW ON TUESDAY. AS THE WEEK PROGRESSES AN UPPER LEVEL
TROUGH FORMS ALONG THE EAST COAST ON FRIDAY AND WILL DRIVE THE
HIGH PRESSURE RIDGE SOUTHWARD.
AT THE SURFACE THE FRONTAL BOUNDARY WILL REMAIN AND THE MODELS
CONTINUE TO SHOW THIS WEAKNESS IN THE SURFACE PRESSURE PATTERN
THROUGH AT LEAST FRIDAY. PRECIPITABLE WATERS WILL REMAIN HIGH AND
THE ONLY UPPER LEVEL SUPPORT MAY BE FROM SHORTWAVE IN THE NORTHWEST
FLOW. 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 IN THE UPPER 80S TO NEAR 90
EACH DAY AND LOWS IN THE LOWER 70 INLAND AND MID 70S AT THE
BEACHES.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
AS OF 00Z...VISIBLE SATELLITE IMAGERY INDICATES KILM HAS SEEN THE
MOST SIGNIFICANT REDUCTION IN CLOUD COVER THIS AFTN/EVENING...AS
CONDITIONS ARE PRESENTLY VFR. ELSEWHERE...MVFR CIGS 1-2KFT LINGER
ACROSS MUCH OF THE CWA...WITH IFR CIGS PERSISTING AT KFLO. THE COOL
MOIST NEAR-SFC LAYER AND WEAK LOW-LEVEL WINDS CERTAINLY FAVOR
FOG/STRATUS AGAIN TONIGHT. EXPECT IFR CIGS TO PREVAIL AT KFLO...
BECOMING LIFR OVERNIGHT. CONDITIONS AT KLBT SHOULD DROP TO IFR
WITHIN THE NEXT FEW HOURS. IFR VSBYS APPEAR LIKELY OVERNIGHT FOR THE
INLAND SITES AS WELL. EXPECT IFR CIGS/MVFR VSBYS AT THE COASTAL
TERMS CLOSER TO 06Z...BEGINNING WITH KMYR FOLLOWED BY KCRE/KILM.
SHORTWAVE ENERGY WITHIN THE SOUTHWEST FLOW ALOFT COULD RESULT IN
MORE SHOWERS INLAND OVERNIGHT...SO HAVE INCLUDED VCSH FOR KFLO/KLBT.
ANY IFR/LIFR CONDITIONS SHOULD IMPROVE TO MVFR AFTER 12Z AND VFR BY
MIDDAY. DIURNAL SHOWERS/T-STORMS ARE CERTAINLY POSSIBLE DURING THE
DAY ON SUNDAY...BUT CHOSE NOT TO MENTION ATTM AS COVERAGE WILL BE
LIMITED. THE WINDS WILL BE LIGHT AND VARIABLE FOR MUCH OF THE
PERIOD...BECOMING SOUTHEAST AOB 10 KTS IN THE AFTN ALONG THE COAST.
EXTENDED OUTLOOK...ISOLATED TO SCATTERED AFTN SHOWERS AND T-STORMS
ARE POSSIBLE THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 PM SATURDAY...SFC PRESSURE PATTERN AND GRADIENT
SOMEWHAT DIFFUSE AND LOOSE ACROSS THE ATLANTIC WATERS. THE
COASTAL FRONTS LOCATION ALONG THE IMMEDIATE COAST HAS MADE WIND
DIRECTIONS RATHER TRICKY. THE SFC PG WILL REMAIN RATHER LOOSE. AS
A RESULT...WIND SPEEDS OVERNIGHT WILL BE AROUND 10 KT. AS FOR THE
DIRECTION...WILL TRY TO FIND A DOMINATE DIRECTION IN LIEU OF GOING
VARIABLE IN DIRECTION. SIGNIFICANT SEAS WILL PRIMARILY BE A
RESULT OF WIND DRIVEN WAVES RUNNING AT 3 TO 5 SECOND PERIODS...WITH
HEIGHTS OF 2 TO 3 FT.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...A WEAK GRADIENT WILL REMAIN OVER THE FORECAST
AREA THROUGH THE PERIOD WITH THE DECAYING FRONT NEARBY. WINDS MAY
WELL BE DRIVEN MORE BY MESOSCALE PROCESSES THAN THE ACTUAL GRADIENT.
THIS MAY MEAN E TO SE WINDS BY DAY AND W TO NW WINDS OVER NIGHT DUE
TO LAND AND SEA BREEZE EFFECTS AND THE SHIFTING POSITION OF THE OLD
FRONT. SPEEDS WILL BE 10 KT OR LESS THROUGH THE PERIOD. SEAS INVOF
2 FT ARE EXPECTED THROUGH THE PERIOD.
LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 3 PM SATURDAY...THE WEAKNESS FROM THE FRONTAL BOUNDARY ALONG
THE COAST APPEARS TO CONTINUE THROUGH THE PERIOD. WITH THIS WEAK
PRESSURE GRADIENT THE WINDS TO BE LESS THAN 10 KNOTS AND VARIABLE.
THE LOCAL WAVE MODEL COUPLED WITH THE WAVEWATCH III MODEL IS SHOWING
SEAS AROUND 2 FEET THROUGH THE ENTIRE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DCH
NEAR TERM...DCH
SHORT TERM...RAN
LONG TERM...DRH
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
817 PM EDT SAT AUG 17 2013
.SYNOPSIS...
LOW PRESSURE WILL EXIT NE OF THE AREA THIS EVENING...AND OFF THE
OUTER BANKS BY DAYBREAK SUNDAY. A FRONTAL SYSTEM DRAPED ALONG THE
IMMEDIATE COAST OF THE CAROLINAS AND HIGH PRESSURE RIDGING
SOUTHWEST ACROSS THE CENTRAL CAROLINAS...WILL BOTH PERSIST INTO
EARLY NEXT WEEK. THE FRONT WILL FINALLY DISSIPATE BY MIDWEEK WITH
WEAK HIGH PRESSURE REMAINING ACROSS THE AREA. THE CHANCE FOR
CONVECTION WILL EXIST EACH AFTERNOON AND EVENING THROUGH THE MID
WEEK PERIOD OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
AS OF 730 PM SATURDAY...NOT MUCH SFC BASED INSTABILITY
TONIGHT VIA LATEST HRRR RUNS. IN FACT TONIGHTS WX MAP/FEATURES
RESEMBLES WHAT OCCURS DURING THE LATE FALL THROUGH EARLY SPRING.
IE. SFC HIGH NOSING/RIDGING FROM THE NE STATES AND A COASTAL
TROF/FRONT ALONG THE IMMEDIATE COAST. SFC LOW HAVING MOVED ALONG
THIS FRONT AND DROPPED A GOOD AMOUNT OF RAIN ALONG THE COAST...IS
NOW NE OF THE AREA...AND PROGGED TO BE OFF THE OUTER BANKS BY
SUNDAY MORNING. DIS NOT EXPECT THE COASTAL FRONT/TROF TO MOVE
ONSHORE DUE TO THE CORRELATION BETWEEN LACK OF SFC AND UPPER
TROFFINESS ACROSS TX/OK. AS FOR TONIGHT...A NEARLY SATURATED ATM
TO EXIST WITH PWS 2+ INCHES. THE SFC BASED INSTABILITY HOWEVER...
WILL BE LACKING VIA LATEST HRRR RUNS AND PROGGED NAMBUFR SOUNDINGS
ACROSS THE AREA. THE LATEST SREF PROBABILITY OF MEASUREABLE PCPN
ACROSS THE AREA TONIGHT INDICATES THE BEST PROBS WILL OCCUR FROM
ACROSS THE LEE-SIDE OF THE APPALACHIANS TO WEST OF I-95. WITH ALL
THIS SAID...WILL LOWER POPS ACROSS THE BOARD TONIGHT AND INDICATE
ISOLATED TO WIDELY SCATTERED IN COVERAGE. WILL OUTLINE ALONG OR
WEST OF THE I-95 CORRIDOR FOR PCPN POPS. AS FOR MINS...SLIGHTLY
TWEAKED A FEW DEGREES LOWER ACROSS THE INLAND 1/3RD OF THE CWA
BASED ON LATEST SFC OBS AND MODEL NMOS GUIDANCE.
PREVIOUS DISCUSSION...............................................
AS OF 3 PM SATURDAY...A FRONT WILL REMAIN OFFSHORE AS A WEAK AREA
OF LOW PRESSURE CENTERED NEAR CAPE FEAR LIFTS N THROUGH THIS EVE.
THE MAJORITY OF SHOWERS WILL LIFT N WITH THIS FEATURE AND FOR THE
MOST PART...SHOWERS WILL BECOME ISOLATED ACROSS THE CAPE FEAR
REGION THROUGH THE EARLY EVE. ELSEWHERE ACROSS THE FORECAST
AREA... SUBSIDENCE ON THE BACK SIDE OF WEAK LOW PRESSURE HAS BEEN
JUST ENOUGH TO SUPPRESS ALL BUT THE BRIEFEST AND LIGHTEST OF
SHOWERS TODAY AND THAT WILL BE THE CASE INTO THIS EVE.
MODELS ARE INDICATING SOME WEAK SHORTWAVE ENERGY EMBEDDED IN
SOUTHWEST FLOW WILL MOVE ACROSS THE UPSTATE OF SOUTH CAROLINA AND
CENTRAL NORTH CAROLINA THIS EVE. SHOWERS ASSOCIATED WITH THIS
FEATURE MAY BRUSH AT LEAST OUR INLAND COUNTIES. THUS...WILL NOT PULL
SHOWERS COMPLETELY FROM THE FORECAST AND WILL KEEP SLIGHT
CHANCE/SMALL CHANCE EVEN AFTER DARK. THE LACK OF INSTABILITY ON THE
COOL SIDE OF THE FRONT SHOULD PRECLUDE THUNDER. WILL INCLUDE AN
ISOLATED THUNDERSTORM FOR THE CAPE FEAR REGION THROUGH THE LATE
AFTERNOON IN CLOSEST PROXIMITY TO THE AREA OF LOW PRESSURE.
WET TO SATURATED SOILS AND LIGHT TO CALM WINDS WILL BE CONDUCIVE FOR
STRATUS TO PERSIST THROUGH THE NIGHT...WITH CEILINGS LOWERING EVEN
FURTHER LATER TONIGHT. HAVE ADDED PATCHY TO AREAS OF FOG AS DEWPOINT
DEPRESSIONS NARROW TO NEAR ZERO DURING THE OVERNIGHT.
AFTER A COOL DAY...TEMPERATURES WILL FALL OFF LESS THAN 10 DEGREES
OVERNIGHT...PUTTING LOWS IN THE UPPER 60S TO LOWER 70S.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...THE OLD FRONT WILL REMAIN ACROSS THE AREA
THROUGH THE PERIOD. AN UPPER LOW TO THE WEST WILL MAINTAIN SW FLOW
ALOFT SUNDAY BUT HIGH PRESSURE RIDGING IN FROM THE EAST WILL SHIFT
THE BEST LIFT AND DEEP MOISTURE TO THE WEST AND NORTH OF THE FA.
MAIN FOCUS FOR PRECIP SUNDAY WILL BE THE FRONT AND DIURNAL HEATING
SO FORECAST HAS CHANCE POPS FOR THE AFTERNOON AND EVENING HOURS AND
SLIGHT CHANCE IN THE MORNING AND OVERNIGHT SUNDAY INTO MONDAY
MORNING. MAXIMUMS SUNDAY WILL BE WARMER AND SHOULD REACH THE LOW TO
MID 80S UNDER PARTLY TO MOSTLY CLOUDY.
ON MONDAY...THE UPPER LOW TO THE WEST WILL EJECT NORTHEASTWARD AND
BRING UPPER SUPPORT FOR PRECIPITATION TO THE AREA AGAIN WITH THE
FRONT IN THE AREA. THE FORECAST WILL HAVE SLIGHTLY HIGHER CHANCE
POPS FOR MONDAY THAN SUNDAY...AGAIN FOCUSING ON THE PRIME DIURNAL
PERIOD FOR CONVECTION. MAXIMUMS MONDAY SHOULD REACH THE MID TO
UPPER 80S UNDER PARTLY TO MOSTLY CLOUDY SKIES. MINS SUNDAY NIGHT
AND MONDAY NIGHT SHOULD BE WITHIN A COUPLE DEGREES OF 70.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 3 PM SATURDAY...THE 500 MB UPPER LEVEL RIDGE AXIS TRIES TO
BUILD WESTWARD AND WILL ALIGNED ALONG A LINE FROM MOBILE TO
SAVANNAH AND OUR REGION WILL BE ON THE SOUTHERN FRINGES OF THE
NORTHWEST FLOW ON TUESDAY. AS THE WEEK PROGRESSES AN UPPER LEVEL
TROUGH FORMS ALONG THE EAST COAST ON FRIDAY AND WILL DRIVE THE
HIGH PRESSURE RIDGE SOUTHWARD.
AT THE SURFACE THE FRONTAL BOUNDARY WILL REMAIN AND THE MODELS
CONTINUE TO SHOW THIS WEAKNESS IN THE SURFACE PRESSURE PATTERN
THROUGH AT LEAST FRIDAY. PRECIPITABLE WATERS WILL REMAIN HIGH AND
THE ONLY UPPER LEVEL SUPPORT MAY BE FROM SHORTWAVE IN THE NORTHWEST
FLOW. 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 IN THE UPPER 80S TO NEAR 90
EACH DAY AND LOWS IN THE LOWER 70 INLAND AND MID 70S AT THE
BEACHES.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
AS OF 00Z...VISIBLE SATELLITE IMAGERY INDICATES KILM HAS SEEN THE
MOST SIGNIFICANT REDUCTION IN CLOUD COVER THIS AFTN/EVENING...AS
CONDITIONS ARE PRESENTLY VFR. ELSEWHERE...MVFR CIGS 1-2KFT LINGER
ACROSS MUCH OF THE CWA...WITH IFR CIGS PERSISTING AT KFLO. THE COOL
MOIST NEAR-SFC LAYER AND WEAK LOW-LEVEL WINDS CERTAINLY FAVOR
FOG/STRATUS AGAIN TONIGHT. EXPECT IFR CIGS TO PREVAIL AT KFLO...
BECOMING LIFR OVERNIGHT. CONDITIONS AT KLBT SHOULD DROP TO IFR
WITHIN THE NEXT FEW HOURS. IFR VSBYS APPEAR LIKELY OVERNIGHT FOR THE
INLAND SITES AS WELL. EXPECT IFR CIGS/MVFR VSBYS AT THE COASTAL
TERMS CLOSER TO 06Z...BEGINNING WITH KMYR FOLLOWED BY KCRE/KILM.
SHORTWAVE ENERGY WITHIN THE SOUTHWEST FLOW ALOFT COULD RESULT IN
MORE SHOWERS INLAND OVERNIGHT...SO HAVE INCLUDED VCSH FOR KFLO/KLBT.
ANY IFR/LIFR CONDITIONS SHOULD IMPROVE TO MVFR AFTER 12Z AND VFR BY
MIDDAY. DIURNAL SHOWERS/T-STORMS ARE CERTAINLY POSSIBLE DURING THE
DAY ON SUNDAY...BUT CHOSE NOT TO MENTION ATTM AS COVERAGE WILL BE
LIMITED. THE WINDS WILL BE LIGHT AND VARIABLE FOR MUCH OF THE
PERIOD...BECOMING SOUTHEAST AOB 10 KTS IN THE AFTN ALONG THE COAST.
EXTENDED OUTLOOK...ISOLATED TO SCATTERED AFTN SHOWERS AND T-STORMS
ARE POSSIBLE THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 745 PM SATURDAY...SFC PRESSURE PATTERN AND GRADIENT SOMEWHAT
DIFFUSE AND LOOSE ACROSS THE ATLANTIC WATERS. THE COASTAL
TROF/FRONTS LOCATION ALONG THE IMMEDIATE COAST HAS MADE WIND
DIRECTIONS RATHER TRICKY. THE SFC PG...EVEN WHEN THE SFC LOW
PASSED BY THIS AFTERNOON...WILL REMAIN RATHER LOOSE. AS A RESULT...
WIND SPEEDS OVERNIGHT WILL BE AROUND 10 KT. AS FOR THE
DIRECTION...WILL TRY TO FIND A DOMINATE DIRECTION IN LIEU OF GOING
VARIABLE IN DIRECTION. SIGNIFICANT SEAS WILL PRIMARILY BE A RESULT
OF WIND DRIVEN WAVES RUNNING AT 3 TO 5 SECOND PERIODS...WITH
HEIGHTS OF 2 TO 3 FT.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...A WEAK GRADIENT WILL REMAIN OVER THE FORECAST
AREA THROUGH THE PERIOD WITH THE DECAYING FRONT NEARBY. WINDS MAY
WELL BE DRIVEN MORE BY MESOSCALE PROCESSES THAN THE ACTUAL GRADIENT.
THIS MAY MEAN E TO SE WINDS BY DAY AND W TO NW WINDS OVER NIGHT DUE
TO LAND AND SEA BREEZE EFFECTS AND THE SHIFTING POSITION OF THE OLD
FRONT. SPEEDS WILL BE 10 KT OR LESS THROUGH THE PERIOD. SEAS INVOF
2 FT ARE EXPECTED THROUGH THE PERIOD.
LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 3 PM SATURDAY...THE WEAKNESS FROM THE FRONTAL BOUNDARY ALONG
THE COAST APPEARS TO CONTINUE THROUGH THE PERIOD. WITH THIS WEAK
PRESSURE GRADIENT THE WINDS TO BE LESS THAN 10 KNOTS AND VARIABLE.
THE LOCAL WAVE MODEL COUPLED WITH THE WAVEWATCH III MODEL IS SHOWING
SEAS AROUND 2 FEET THROUGH THE ENTIRE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DCH
NEAR TERM...DCH/RJD
SHORT TERM...RAN
LONG TERM...DRH
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
230 PM EDT FRI AUG 16 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC WILL EXTEND
SOUTHWARD INTO THE CAROLINAS THROUGH THE WEEKEND... AS WEAK WAVES OF
LOW PRESSURE DEVELOP ALONG A STALLED FRONT ACROSS THE DEEP SOUTH AND
SOUTHEAST COAST.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM FRIDAY...
A 1022MB SURFACE HIGH OVER PA/MD EXTENDS SOUTH INTO THE CAROLINAS
THIS MORNING...WITH A STATIONARY FRONT DRAPED ACROSS COASTAL SC AND
GEORGIA IN A CAD-LIKE PATTERN. ALOFT...AND UPPER JET STREAK
EJECTING OUT OF THE BASE OF THE LW TROUGH IS EVIDENT IN WATER VAPOR
IMAGERY OVER NORTHERN GEORGIA. IN RESPONSE...WIDESPREAD PRECIP HAS
BROKEN OUT OVER THE WESTERN HALF OF SC...BUT IS STRUGGLING TO MOVE
NORTH OF THE 925-850MB FRONTAL ZONE...WHICH IS LOCATED NEAR THE
NC/SC BORDER. MID/HIGH CLOUDS ARE POURING INTO THE CWA FROM THE
SOUTHWEST...BUT UNTIL THE 850MB FRONT BEGINS TO PUSH NORTH...WHICH
WILL HAPPEN ONLY SLOWLY BETWEEN NOW AND 00Z THIS EVENING...PRECIP
WILL CONTINUE TO STRUGGLE TO MOVE INTO THE DRY AIR RIDGE.. WITH
SUPPORT FROM HRRR AND OTHER HI-RES WRF MODELS...EXPECT PRECIP TO
SPREAD MORE EAST THAN NORTH ALONG THE BETTER LOW-LEVEL FORCING
THROUGH EARLY AFTERNOON. HAVE REMOVED POPS FROM THE NORTHERN
PIEDMONT AND NORTHERN COASTAL PLAIN...WITH A VERY TIGHT GRADIENT
NEAR THE HWY 64 CORRIDOR AND CATEGORICAL POPS NEAR THE SC BORDER
WILL MAKE SOME SMALL ADJUSTMENTS TO HIGHS BASED ON THE LACK OF
PRECIP FOR MOST OF THE CWA...BUT INCREASING CLOUD COVER WILL STILL
TEMPER HEATING AND THE PREVIOUS FORECAST APPEARS TO BE MOSTLY IN
TRACK. HIGHS IN THE UPPER 60S IN THE SOUTHWEST AND UPPER 70S IN
THE NORTHEAST. -SMITH
TONIGHT...A STRONGER MID-UPPER LEVEL S/W SEEN ON WATER VAPOR IMAGERY
DIVING SWD ACROSS THE CENTRAL PLAINS THIS MORNING WILL DIG INTO THE
BOTTOM OF THE L/W TROUGH....BACKING OUR MID-UPPER LEVEL FLOW TO A
MORE SWLY DIRECTION. IN ADDITION THIS FEATURE WILL ENHANCE THE SLY
FLOW A FEW THOUSAND FEET ABOVE THE SURFACE...INCREASING ISENTROPIC
LIFT. THIS WILL LEAD TO RAIN/RAIN SHOWERS BECOMING WIDESPREAD AND
INCREASE IN INTENSITY ACROSS CENTRAL NC TONIGHT. HAVE INCREASED POPS
TO CATEGORICAL OVER THE SW TWO-THIRDS OF THE FORECAST AREA WITH
LIKELY POPS OVER THE NE. MIN TEMPS LOWER 60S NW TO THE UPPER 60S SE.
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 300 AM FRIDAY...
SATURDAY...THE RAIN OVERNIGHT WILL LOCK IN A HYBRID COLD AIR DAMMING
AIR MASS ACROSS THE PIEDMONT. CONTINUED ISENTROPIC LIFT IN
CONJUNCTION OF THE AREA OF LOW PRESSURE OVER THE LOWER MS VALLEY
WILL CAUSE WIDESPREAD LOW CLOUDS AND PERSISTENT RAIN. THIS WILL
RESULT IN A DIURNAL TEMP RECOVERY OF NO MORE THAN 4-5 DEGREES ACROSS
THE NW PIEDMONT...AND 5-7 DEGREES ACROSS THE REMAINDER OF THE
PIEDMONT AND COASTAL PLAIN. MAX TEMPS MID-UPPER 60S NW TO MID-UPPER
70S FAR SE.
HAVE INCREASED POPS TO CATEGORICAL SATURDAY AND LOWERED
MAX TEMPS A DEGREE OR TWO FROM THE PREVIOUS FORECAST. WHILE RAIN
WILL OCCUR FOR MOST OF THE DAY...NOT ANTICIPATING AMOUNTS THAT WOULD
WARRANT THE ISSUANCE OF A FLASH FLOOD WATCH. THAT BEING SAID...WHERE
POCKETS OF MODERATE RAINFALL DUE SET-UP...RAINFALL RATES OF A THIRD
TO A HALF INCH PER HOUR FOR A FEW HOURS WILL CAUSE EXTENSIVE PONDING
OF WATER AND NUISANCE FLOODING OF POOR DRAINAGE AREAS.
SATURDAY NIGHT...CONTINUED SW FLOW ALOFT WITH EMBEDDED DISTURBANCES
INTERACTING WITH THE MOISTURE RICH AIR MASS AND CONTINUED LOW LEVEL
OVERRUNNING WILL MAINTAIN HIGHER THAN NORMAL POPS ACROSS CENTRAL NC.
EXPECT LIKELY POPS TO SUFFICE BUT WOULD NOT BE SURPRISED IF
CATEGORICAL POPS NEEDED IN LATER FORECAST ISSUANCE. TEMPS WILL HOLD
STEADY OR ONLY LOWER A FEW DEGREES FROM OBSERVED HIGH TEMPS ON
SATURDAY. MAY SEE WIDESPREAD AREAS OF FOG DEVELOP OVERNIGHT...
ESPECIALLY ACROSS THE PIEDMONT. MIN TEMPS LOW-MID 60S PIEDMONT TO
THE UPPER 60S IN THE COASTAL PLAIN AND SANDHILLS.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
AS OF 230 PM FRIDAY...
THE LONG TERM PERIOD OF THE FORECAST FEATURES AN UNSETTLED PATTERN
WITH A WETTER THAN NORMAL ATMOSPHERE AND GREATER THAN TYPICAL
UNCERTAINTY IN FORECAST DETAILS.
THE CLOSED UPPER TROUGH OVER THE MID MISSISSIPPI VALLEY ON SUNDAY
OPENS UP AND LIFTS OUT ACROSS THE MID ATLANTIC REGION ON MONDAY. A
SURGE OF ISENTROPIC LIFT MOVES ACROSS THE NC/VA EARLY SUNDAY AHEAD
OF THE EXITING TROUGH RESULTING IN HIGH POPS. A LINGERING COLD AIR
DAMMING AIR MASS IS EXPECTED ACROSS THE INTERIOR PIEDMONT FOR SUNDAY
INTO MONDAY WITH WEAK FORCING AND WIDELY SCATTERED POPS.
HEIGHTS BEGIN TO RISE SLIGHTLY ON MONDAY INTO TUESDAY AS THE
SUBTROPICAL RIDGE ADVANCES WEST BUT AN AXIS OF HIGHER PRECIPITABLE
WATER LINGERS ACROSS THE SOUTHERN CAROLINAS DURING THE PERIOD.
PREDICTABILITY IS LOW BUT BOTH THE GFS/ECMWF SUGGEST A WEAK SURFACE
TROUGH IS LIKELY TO BE LINGERING SOMEWHERE ACROSS SOUTHERN PORTIONS
OF THE REGION SUGGESTING THAT POPS ON TUESDAY AND WEDNESDAY SHOULD
BE LOWER THAN PREVIOUS DAYS AND GREATEST IN THE SOUTHERN PORTIONS OF
THE FORECAST AREA.
LATER IN THE PERIOD GUIDANCE HAS TRENDED TOWARD A REDEVELOPMENT OF
THE EASTERN CONUS TROUGH IN PART RESULTING FROM A SOUTHWARD SHIFT OF
THE WESTERLIES IN SOUTHERN CANADA ON THURSDAY INTO FRIDAY. THE
RESULT IS AN INCREASE IN DEEP LAYER MOISTURE AND LOWERING HEIGHTS
ACROSS THE CAROLINAS LATE IN THE WORK WEEK WITH A TENDENCY FOR
SCATTERED AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS...ESPECIALLY ACROSS SOUTHERN AND EASTERN PORTIONS OF
THE FORECAST AREA.
A LINGERING COLD AIR DAMMING TEMPERATURE REGIME IS EXPECTED ON
SUNDAY AND INTO MONDAY WITH LIMITED DIURNAL RANGE AND MUCH BELOW
NORMAL MAX TEMPERATURES ACROSS THE NORTHWEST PIEDMONT. TEMPERATURES
IN GENERAL WILL MODERATE AND WARM TO AROUND SEASONABLE MAX
TEMPERATURES FOR WEDNESDAY THROUGH FRIDAY WITH SLIGHTLY ABOVE
AVERAGE MINIMUM TEMPERATURES. -BLAES
&&
.AVIATION /18Z FRIDAY THROUGH TUESDAY/...
AS OF 145 PM FRIDAY...
AN EXPANDING AREA OF LIGHT TO MODERATE RAIN OVER SC IS MOVING INTO
THE SOUTHERN PORTIONS OF NC...THOUGH VFR CONDITIONS ARE STILL
OBSERVED AT ALL TAF SITES. THIS PRECIP...AND CORRESPONDING LOWERING
OF CEILINGS...IS EXPECTED TO SPREAD FROM KFAY TO KRWI THIS
AFTERNOON..WITH KRDU LIKELY JUST ON THE EDGE OF THE RAIN SHIELD AND
SUB-VFR CONDITIONS. ANOTHER...MORE WIDESPREAD ROUND OF PRECIP IS
EXPECTED TO MOVE INTO CENTRAL NC FROM THE OVERNIGHT AND CONTINUE
DURING THE DAY SATURDAY. MOST MODELS INDICATE MVFR CEILINGS WILL
DEVELOP IN THE KFAY AREA BY 00Z THIS EVENING...LOWERING TO IFR AFTER
MIDNIGHT. FURTHER NORTH...MVFR CEILINGS WILL BE DELAYED...BUT A
GENERAL LOWER TO IFR LEVELS IS EXPECTED BY SATURDAY MORNING. THERE
IS MEDIUM TO HIGH CONFIDENCE IN THE POOR AVIATION CONDITIONS DURING
THE CURRENT TAF PERIOD.
OUTLOOK...
WIDESPREAD RAIN WILL CONTINUE INTO SATURDAY NIGHT..WITH IMPROVEMENT
EXPECTED FROM SOUTH TO NORTH BY SUNDAY. HOWEVER...SUB-VFR
CONDITIONS WILL LIKELY PERSIST THROUGH SUNDAY AND EVEN INTO MONDAY
IN THE TRIAD AREA.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...WSS/SMITH
SHORT TERM...WSS
LONG TERM...BLAES
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
145 PM EDT FRI AUG 16 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC WILL EXTEND
SOUTHWARD INTO THE CAROLINAS THROUGH THE WEEKEND... AS WEAK WAVES OF
LOW PRESSURE DEVELOP ALONG A STALLED FRONT ACROSS THE DEEP SOUTH AND
SOUTHEAST COAST.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM FRIDAY...
A 1022MB SURFACE HIGH OVER PA/MD EXTENDS SOUTH INTO THE CAROLINAS
THIS MORNING...WITH A STATIONARY FRONT DRAPED ACROSS COASTAL SC AND
GEORGIA IN A CAD-LIKE PATTERN. ALOFT...AND UPPER JET STREAK
EJECTING OUT OF THE BASE OF THE LW TROUGH IS EVIDENT IN WATER VAPOR
IMAGERY OVER NORTHERN GEORGIA. IN RESPONSE...WIDESPREAD PRECIP HAS
BROKEN OUT OVER THE WESTERN HALF OF SC...BUT IS STRUGGLING TO MOVE
NORTH OF THE 925-850MB FRONTAL ZONE...WHICH IS LOCATED NEAR THE
NC/SC BORDER. MID/HIGH CLOUDS ARE POURING INTO THE CWA FROM THE
SOUTHWEST...BUT UNTIL THE 850MB FRONT BEGINS TO PUSH NORTH...WHICH
WILL HAPPEN ONLY SLOWLY BETWEEN NOW AND 00Z THIS EVENING...PRECIP
WILL CONTINUE TO STRUGGLE TO MOVE INTO THE DRY AIR RIDGE.. WITH
SUPPORT FROM HRRR AND OTHER HI-RES WRF MODELS...EXPECT PRECIP TO
SPREAD MORE EAST THAN NORTH ALONG THE BETTER LOW-LEVEL FORCING
THROUGH EARLY AFTERNOON. HAVE REMOVED POPS FROM THE NORTHERN
PIEDMONT AND NORTHERN COASTAL PLAIN...WITH A VERY TIGHT GRADIENT
NEAR THE HWY 64 CORRIDOR AND CATEGORICAL POPS NEAR THE SC BORDER
WILL MAKE SOME SMALL ADJUSTMENTS TO HIGHS BASED ON THE LACK OF
PRECIP FOR MOST OF THE CWA...BUT INCREASING CLOUD COVER WILL STILL
TEMPER HEATING AND THE PREVIOUS FORECAST APPEARS TO BE MOSTLY IN
TRACK. HIGHS IN THE UPPER 60S IN THE SOUTHWEST AND UPPER 70S IN
THE NORTHEAST. -SMITH
TONIGHT...A STRONGER MID-UPPER LEVEL S/W SEEN ON WATER VAPOR IMAGERY
DIVING SWD ACROSS THE CENTRAL PLAINS THIS MORNING WILL DIG INTO THE
BOTTOM OF THE L/W TROUGH....BACKING OUR MID-UPPER LEVEL FLOW TO A
MORE SWLY DIRECTION. IN ADDITION THIS FEATURE WILL ENHANCE THE SLY
FLOW A FEW THOUSAND FEET ABOVE THE SURFACE...INCREASING ISENTROPIC
LIFT. THIS WILL LEAD TO RAIN/RAIN SHOWERS BECOMING WIDESPREAD AND
INCREASE IN INTENSITY ACROSS CENTRAL NC TONIGHT. HAVE INCREASED POPS
TO CATEGORICAL OVER THE SW TWO-THIRDS OF THE FORECAST AREA WITH
LIKELY POPS OVER THE NE. MIN TEMPS LOWER 60S NW TO THE UPPER 60S SE.
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 300 AM FRIDAY...
SATURDAY...THE RAIN OVERNIGHT WILL LOCK IN A HYBRID COLD AIR DAMMING
AIR MASS ACROSS THE PIEDMONT. CONTINUED ISENTROPIC LIFT IN
CONJUNCTION OF THE AREA OF LOW PRESSURE OVER THE LOWER MS VALLEY
WILL CAUSE WIDESPREAD LOW CLOUDS AND PERSISTENT RAIN. THIS WILL
RESULT IN A DIURNAL TEMP RECOVERY OF NO MORE THAN 4-5 DEGREES ACROSS
THE NW PIEDMONT...AND 5-7 DEGREES ACROSS THE REMAINDER OF THE
PIEDMONT AND COASTAL PLAIN. MAX TEMPS MID-UPPER 60S NW TO MID-UPPER
70S FAR SE.
HAVE INCREASED POPS TO CATEGORICAL SATURDAY AND LOWERED
MAX TEMPS A DEGREE OR TWO FROM THE PREVIOUS FORECAST. WHILE RAIN
WILL OCCUR FOR MOST OF THE DAY...NOT ANTICIPATING AMOUNTS THAT WOULD
WARRANT THE ISSUANCE OF A FLASH FLOOD WATCH. THAT BEING SAID...WHERE
POCKETS OF MODERATE RAINFALL DUE SET-UP...RAINFALL RATES OF A THIRD
TO A HALF INCH PER HOUR FOR A FEW HOURS WILL CAUSE EXTENSIVE PONDING
OF WATER AND NUISANCE FLOODING OF POOR DRAINAGE AREAS.
SATURDAY NIGHT...CONTINUED SW FLOW ALOFT WITH EMBEDDED DISTURBANCES
INTERACTING WITH THE MOISTURE RICH AIR MASS AND CONTINUED LOW LEVEL
OVERRUNNING WILL MAINTAIN HIGHER THAN NORMAL POPS ACROSS CENTRAL NC.
EXPECT LIKELY POPS TO SUFFICE BUT WOULD NOT BE SURPRISED IF
CATEGORICAL POPS NEEDED IN LATER FORECAST ISSUANCE. TEMPS WILL HOLD
STEADY OR ONLY LOWER A FEW DEGREES FROM OBSERVED HIGH TEMPS ON
SATURDAY. MAY SEE WIDESPREAD AREAS OF FOG DEVELOP OVERNIGHT...
ESPECIALLY ACROSS THE PIEDMONT. MIN TEMPS LOW-MID 60S PIEDMONT TO
THE UPPER 60S IN THE COASTAL PLAIN AND SANDHILLS.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 300 AM FRIDAY...
THE MEDIUM RANGE PORTION OF THE FORECAST WILL TRANSITION FROM A WARM
SEASON CAD EVENT OVER THIS WEEKEND TO MORE TYPICAL AFTERNOON AND
EVENING SCATTERED SHOWERS AND STORMS PATTERN AND NEAR NEAR NORMAL
TEMPS BY NEXT WEEK
SUNDAY AND SUNDAY NIGHT:
THE PRIMARY SURFACE LOW ASSOCIATED WITH THE SYSTEM MENTIONED IN THE
NEAR/SHORT TERM PARTS OF THE FORECAST IS EXPECTED TO LIFT
NORTHEASTWARD FROM THE NC COAST SUNDAY MORNING TO OFF THE
VA/MID-ATLANTIC COAST BY SUNDAY AFTERNOON/EVENING. HOWEVER... MOST
GUIDANCE SHOWS CONTINUED GOOD CHANCES FOR PRECIP ACROSS OUR
NORTHWEST/WEST ASSOCIATED WITH WEAK ISENTROPIC UPGLIDE AND A
POSSIBLE IMPULSE ALOFT MOVING THROUGH THE SOUTH-SOUTHWESTERLY FLOW.
HOWEVER... PRECIP AMOUNTS ARE EXPECTED TO BE LIGHTER THAN ON
SATURDAY. FOR LOCATIONS ACROSS THE NORTHWEST/WEST WHERE THE CAD WILL
HOLD... EXPECT AN OVERCAST... DAMP/WET... COOL DAY. FURTHER EAST AND
SOUTHEAST ACROSS OUR COASTAL PLAIN AND EASTERN SANDHILL COUNTIES
EXPECT WE WILL SEE MORE ISOLATED TO SCATTERED ACTIVITY ON SUNDAY. WE
WILL SEE THE COASTAL FRONT REMAIN TO THE EAST OF THE AREA STILL.
HOWEVER... THE CAD BOUNDARY MAY RETREAT TO THE WEST OF THIS AREA. IF
WE DO SEE A FEW BREAKS IN THE CLOUDS BY AFTERNOON WE MAY SEE SOME
INSTABILITY DEVELOP... RESULTING IN A CHANCE OF SOME SHOWERS AND
EVEN SOME STORMS. FOR NOW WILL GO WITH CHANCE POPS FOR ALL DAY
SUNDAY HERE... WITH THE MAIN THREAT FOR ANY STORMS EXPECTED IN THE
AFTERNOON. FOR LOCATIONS THAT DO SEE THE CAD BOUNDARY RETREAT WE
WILL SEE TEMPS WARM UP SOME... BUT STILL BELOW SEASONAL NORMS.
EXPECT HIGHS SUNDAY WILL RANGE FROM THE LOWER 70S NW TO LOWER 80S TO
MAYBE EVEN MID 80S SE.
WILL CONTINUE TO ADVERTISE A CHANCE OF SHOWERS/RAIN ON SUNDAY NIGHT
ACROSS THE AREA. HOWEVER... THE TROUGH ALOFT CENTERED TO OUR WEST
ACROSS THE OH/TN VALLEY WILL WEAKEN AND BEGIN LIFTING NORTHEASTWARD.
LOW TEMPS MONDAY MORNING ARE EXPECTED TO BE IN THE 66-71 DEGREE
RANGE IN A NW TO SE FASHION.
MONDAY THROUGH THURSDAY:
THE TROUGH ALOFT MENTIONED ABOVE WILL CONTINUE TO WEAKEN AS IT
SLOWLY LIFT NORTHEASTWARD EARN NEXT WEEK. HOWEVER... MEDIUM RANGE
MODEL GUIDANCE HAS BEEN HINTING AT THE POSSIBILITY OF THE WEAKENING
SHEAR-AXIS LINGERING ACROSS THE AREA. GIVEN THE EXPECTED LINGERING
MOIST LOW LEVEL AIRMASS OVER OUR REGION AND PW`S GENERALLY RANGING
FROM 1.5 TO 2.0 INCHES EXPECT WE WILL SEE AT LEAST ISOLATED TO
SCATTERED AFTERNOON/EVENING CONVECTION EACH DAY... ESPECIALLY ON
MONDAY AND TUESDAY... WITH THE POTENTIAL FOR A LINGERING CAD
BOUNDARY ON MONDAY. THIS PATTERN WILL YIELD A TRANSITION BACK TO
NEAR NORMAL TEMPS BY MID/LATE WEEK AND A MORE TYPICAL SUMMERTIME
WEATHER.
&&
.AVIATION /18Z FRIDAY THROUGH TUESDAY/...
AS OF 145 PM FRIDAY...
AN EXPANDING AREA OF LIGHT TO MODERATE RAIN OVER SC IS MOVING INTO
THE SOUTHERN PORTIONS OF NC...THOUGH VFR CONDITIONS ARE STILL
OBSERVED AT ALL TAF SITES. THIS PRECIP...AND CORRESPONDING LOWERING
OF CEILINGS...IS EXPECTED TO SPREAD FROM KFAY TO KRWI THIS
AFTERNOON..WITH KRDU LIKELY JUST ON THE EDGE OF THE RAIN SHIELD AND
SUB-VFR CONDITIONS. ANOTHER...MORE WIDESPREAD ROUND OF PRECIP IS
EXPECTED TO MOVE INTO CENTRAL NC FROM THE OVERNIGHT AND CONTINUE
DURING THE DAY SATURDAY. MOST MODELS INDICATE MVFR CEILINGS WILL
DEVELOP IN THE KFAY AREA BY 00Z THIS EVENING...LOWERING TO IFR AFTER
MIDNIGHT. FURTHER NORTH...MVFR CEILINGS WILL BE DELAYED...BUT A
GENERAL LOWER TO IFR LEVELS IS EXPECTED BY SATURDAY MORNING. THERE
IS MEDIUM TO HIGH CONFIDENCE IN THE POOR AVIATION CONDITIONS DURING
THE CURRENT TAF PERIOD.
OUTLOOK...
WIDESPREAD RAIN WILL CONTINUE INTO SATURDAY NIGHT..WITH IMPROVEMENT
EXPECTED FROM SOUTH TO NORTH BY SUNDAY. HOWEVER...SUB-VFR
CONDITIONS WILL LIKELY PERSIST THROUGH SUNDAY AND EVEN INTO MONDAY
IN THE TRIAD AREA.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...WSS/SMITH
SHORT TERM...WSS
LONG TERM...BSD
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1015 AM EDT FRI AUG 16 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC WILL EXTEND
SOUTHWARD INTO THE CAROLINAS THROUGH THE WEEKEND... AS WEAK WAVES OF
LOW PRESSURE DEVELOP ALONG A STALLED FRONT ACROSS THE DEEP SOUTH AND
SOUTHEAST COAST.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM FRIDAY...
A 1022MB SURFACE HIGH OVER PA/MD EXTENDS SOUTH INTO THE CAROLINAS
THIS MORNING...WITH A STATIONARY FRONT DRAPED ACROSS COASTAL SC AND
GEORGIA IN A CAD-LIKE PATTERN. ALOFT...AND UPPER JET STREAK
EJECTING OUT OF THE BASE OF THE LW TROUGH IS EVIDENT IN WATER VAPOR
IMAGERY OVER NORTHERN GEORGIA. IN RESPONSE...WIDESPREAD PRECIP HAS
BROKEN OUT OVER THE WESTERN HALF OF SC...BUT IS STRUGGLING TO MOVE
NORTH OF THE 925-850MB FRONTAL ZONE...WHICH IS LOCATED NEAR THE
NC/SC BORDER. MID/HIGH CLOUDS ARE POURING INTO THE CWA FROM THE
SOUTHWEST...BUT UNTIL THE 850MB FRONT BEGINS TO PUSH NORTH...WHICH
WILL HAPPEN ONLY SLOWLY BETWEEN NOW AND 00Z THIS EVENING...PRECIP
WILL CONTINUE TO STRUGGLE TO MOVE INTO THE DRY AIR RIDGE.. WITH
SUPPORT FROM HRRR AND OTHER HI-RES WRF MODELS...EXPECT PRECIP TO
SPREAD MORE EAST THAN NORTH ALONG THE BETTER LOW-LEVEL FORCING
THROUGH EARLY AFTERNOON. HAVE REMOVED POPS FROM THE NORTHERN
PIEDMONT AND NORTHERN COASTAL PLAIN...WITH A VERY TIGHT GRADIENT
NEAR THE HWY 64 CORRIDOR AND CATEGORICAL POPS NEAR THE SC BORDER
WILL MAKE SOME SMALL ADJUSTMENTS TO HIGHS BASED ON THE LACK OF
PRECIP FOR MOST OF THE CWA...BUT INCREASING CLOUD COVER WILL STILL
TEMPER HEATING AND THE PREVIOUS FORECAST APPEARS TO BE MOSTLY IN
TRACK. HIGHS IN THE UPPER 60S IN THE SOUTHWEST AND UPPER 70S IN
THE NORTHEAST. -SMITH
TONIGHT...A STRONGER MID-UPPER LEVEL S/W SEEN ON WATER VAPOR IMAGERY
DIVING SWD ACROSS THE CENTRAL PLAINS THIS MORNING WILL DIG INTO THE
BOTTOM OF THE L/W TROUGH....BACKING OUR MID-UPPER LEVEL FLOW TO A
MORE SWLY DIRECTION. IN ADDITION THIS FEATURE WILL ENHANCE THE SLY
FLOW A FEW THOUSAND FEET ABOVE THE SURFACE...INCREASING ISENTROPIC
LIFT. THIS WILL LEAD TO RAIN/RAIN SHOWERS BECOMING WIDESPREAD AND
INCREASE IN INTENSITY ACROSS CENTRAL NC TONIGHT. HAVE INCREASED POPS
TO CATEGORICAL OVER THE SW TWO-THIRDS OF THE FORECAST AREA WITH
LIKELY POPS OVER THE NE. MIN TEMPS LOWER 60S NW TO THE UPPER 60S SE.
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 300 AM FRIDAY...
SATURDAY...THE RAIN OVERNIGHT WILL LOCK IN A HYBRID COLD AIR DAMMING
AIR MASS ACROSS THE PIEDMONT. CONTINUED ISENTROPIC LIFT IN
CONJUNCTION OF THE AREA OF LOW PRESSURE OVER THE LOWER MS VALLEY
WILL CAUSE WIDESPREAD LOW CLOUDS AND PERSISTENT RAIN. THIS WILL
RESULT IN A DIURNAL TEMP RECOVERY OF NO MORE THAN 4-5 DEGREES ACROSS
THE NW PIEDMONT...AND 5-7 DEGREES ACROSS THE REMAINDER OF THE
PIEDMONT AND COASTAL PLAIN. MAX TEMPS MID-UPPER 60S NW TO MID-UPPER
70S FAR SE.
HAVE INCREASED POPS TO CATEGORICAL SATURDAY AND LOWERED
MAX TEMPS A DEGREE OR TWO FROM THE PREVIOUS FORECAST. WHILE RAIN
WILL OCCUR FOR MOST OF THE DAY...NOT ANTICIPATING AMOUNTS THAT WOULD
WARRANT THE ISSUANCE OF A FLASH FLOOD WATCH. THAT BEING SAID...WHERE
POCKETS OF MODERATE RAINFALL DUE SET-UP...RAINFALL RATES OF A THIRD
TO A HALF INCH PER HOUR FOR A FEW HOURS WILL CAUSE EXTENSIVE PONDING
OF WATER AND NUISANCE FLOODING OF POOR DRAINAGE AREAS.
SATURDAY NIGHT...CONTINUED SW FLOW ALOFT WITH EMBEDDED DISTURBANCES
INTERACTING WITH THE MOISTURE RICH AIR MASS AND CONTINUED LOW LEVEL
OVERRUNNING WILL MAINTAIN HIGHER THAN NORMAL POPS ACROSS CENTRAL NC.
EXPECT LIKELY POPS TO SUFFICE BUT WOULD NOT BE SURPRISED IF
CATEGORICAL POPS NEEDED IN LATER FORECAST ISSUANCE. TEMPS WILL HOLD
STEADY OR ONLY LOWER A FEW DEGREES FROM OBSERVED HIGH TEMPS ON
SATURDAY. MAY SEE WIDESPREAD AREAS OF FOG DEVELOP OVERNIGHT...
ESPECIALLY ACROSS THE PIEDMONT. MIN TEMPS LOW-MID 60S PIEDMONT TO
THE UPPER 60S IN THE COASTAL PLAIN AND SANDHILLS.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 300 AM FRIDAY...
THE MEDIUM RANGE PORTION OF THE FORECAST WILL TRANSITION FROM A WARM
SEASON CAD EVENT OVER THIS WEEKEND TO MORE TYPICAL AFTERNOON AND
EVENING SCATTERED SHOWERS AND STORMS PATTERN AND NEAR NEAR NORMAL
TEMPS BY NEXT WEEK
SUNDAY AND SUNDAY NIGHT:
THE PRIMARY SURFACE LOW ASSOCIATED WITH THE SYSTEM MENTIONED IN THE
NEAR/SHORT TERM PARTS OF THE FORECAST IS EXPECTED TO LIFT
NORTHEASTWARD FROM THE NC COAST SUNDAY MORNING TO OFF THE
VA/MID-ATLANTIC COAST BY SUNDAY AFTERNOON/EVENING. HOWEVER... MOST
GUIDANCE SHOWS CONTINUED GOOD CHANCES FOR PRECIP ACROSS OUR
NORTHWEST/WEST ASSOCIATED WITH WEAK ISENTROPIC UPGLIDE AND A
POSSIBLE IMPULSE ALOFT MOVING THROUGH THE SOUTH-SOUTHWESTERLY FLOW.
HOWEVER... PRECIP AMOUNTS ARE EXPECTED TO BE LIGHTER THAN ON
SATURDAY. FOR LOCATIONS ACROSS THE NORTHWEST/WEST WHERE THE CAD WILL
HOLD... EXPECT AN OVERCAST... DAMP/WET... COOL DAY. FURTHER EAST AND
SOUTHEAST ACROSS OUR COASTAL PLAIN AND EASTERN SANDHILL COUNTIES
EXPECT WE WILL SEE MORE ISOLATED TO SCATTERED ACTIVITY ON SUNDAY. WE
WILL SEE THE COASTAL FRONT REMAIN TO THE EAST OF THE AREA STILL.
HOWEVER... THE CAD BOUNDARY MAY RETREAT TO THE WEST OF THIS AREA. IF
WE DO SEE A FEW BREAKS IN THE CLOUDS BY AFTERNOON WE MAY SEE SOME
INSTABILITY DEVELOP... RESULTING IN A CHANCE OF SOME SHOWERS AND
EVEN SOME STORMS. FOR NOW WILL GO WITH CHANCE POPS FOR ALL DAY
SUNDAY HERE... WITH THE MAIN THREAT FOR ANY STORMS EXPECTED IN THE
AFTERNOON. FOR LOCATIONS THAT DO SEE THE CAD BOUNDARY RETREAT WE
WILL SEE TEMPS WARM UP SOME... BUT STILL BELOW SEASONAL NORMS.
EXPECT HIGHS SUNDAY WILL RANGE FROM THE LOWER 70S NW TO LOWER 80S TO
MAYBE EVEN MID 80S SE.
WILL CONTINUE TO ADVERTISE A CHANCE OF SHOWERS/RAIN ON SUNDAY NIGHT
ACROSS THE AREA. HOWEVER... THE TROUGH ALOFT CENTERED TO OUR WEST
ACROSS THE OH/TN VALLEY WILL WEAKEN AND BEGIN LIFTING NORTHEASTWARD.
LOW TEMPS MONDAY MORNING ARE EXPECTED TO BE IN THE 66-71 DEGREE
RANGE IN A NW TO SE FASHION.
MONDAY THROUGH THURSDAY:
THE TROUGH ALOFT MENTIONED ABOVE WILL CONTINUE TO WEAKEN AS IT
SLOWLY LIFT NORTHEASTWARD EARN NEXT WEEK. HOWEVER... MEDIUM RANGE
MODEL GUIDANCE HAS BEEN HINTING AT THE POSSIBILITY OF THE WEAKENING
SHEAR-AXIS LINGERING ACROSS THE AREA. GIVEN THE EXPECTED LINGERING
MOIST LOW LEVEL AIRMASS OVER OUR REGION AND PW`S GENERALLY RANGING
FROM 1.5 TO 2.0 INCHES EXPECT WE WILL SEE AT LEAST ISOLATED TO
SCATTERED AFTERNOON/EVENING CONVECTION EACH DAY... ESPECIALLY ON
MONDAY AND TUESDAY... WITH THE POTENTIAL FOR A LINGERING CAD
BOUNDARY ON MONDAY. THIS PATTERN WILL YIELD A TRANSITION BACK TO
NEAR NORMAL TEMPS BY MID/LATE WEEK AND A MORE TYPICAL SUMMERTIME
WEATHER.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 745 AM FRIDAY...
AVIATION WEATHER CONDITIONS ACROSS CENTRAL NC WILL SLOWLY
DETERIORATE FROM THE SOUTH LATER THIS MORNING...ESPECIALLY AFTER
15Z...AS AN UPPER LEVEL DISTURBANCE LIFTS NEWD TOWARD THE CAROLINAS.
THIS WEATHER FEATURE WILL STRENGTHEN THE SLY WINDS A FEW THOUSAND
FEET ABOVE SURFACE...PULLING MOISTURE OVER THE COOL DRY STABLE AIR
MASS AT THE SURFACE. THIS WILL CAUSE CLOUD BASES TO LOWER AND
POCKETS OF LIGHT RAIN TO BREAK OUT. THESE POCKETS OF RAIN WILL
FURTHER SATURATE THE LOW LEVEL AIR MASS...LEADING TO WIDESPREAD MVFR
CEILINGS IN THE KFAY VICINITY BY EARLY AFTERNOON...AND AT KRDU AND
KRWI BY LATE AFTERNOON. CEILINGS WILL LIKELY LOWER INTO THE MVFR
CATEGORY IN THE TRIAD BY SUNSET. AREAS OF RAIN ARE EXPECTED TO
BECOME NUMEROUS OVER THE SOUTH BY LATE MORNING...AND OVER THE
NORTHERN COUNTIES BY LATE AFTERNOON-EARLY EVENING...RESULTING IN
MVFR/IFR VISIBILITIES IN RAIN AND/OR FOG. WIDESPREAD IFR CONDITIONS
DUE TO LOW CLOUDS AND FOG ANTICIPATED FOR TONIGHT.
ADVERSE AVIATION WEATHER CONDITIONS WILL PERSIST INTO SATURDAY AND
SATURDAY NIGHT WITH PERIODS OF WIDESPREAD LIGHT-MODERATE RAIN AND
CEILINGS IN THE IFR/LOW END MVFR RANGE THROUGH THE ENTIRE PERIOD.
AVIATION CONDITIONS WILL REMAIN PROBLEMATIC SUNDAY THOUGH THE AREAS
OF RAIN WILL BECOME LESS NUMEROUS...ESPECIALLY ACROSS THE COASTAL
PLAIN AND SANDHILLS. HOWEVER WIDESPREAD MVFR CEILINGS WITH AREAS OF
IFR WILL PERSIST THROUGH SUNDAY INTO SUNDAY NIGHT.
ANY IMPROVEMENT IN AVIATION WEATHER CONDITIONS WILL BE SLOW TO OCCUR
MONDAY INTO TUESDAY. THE AIR MASS IS PROJECTED TO REMAIN QUITE MOIST
WITH A CONTINUED THREAT FOR SHOWERS. IN ADDITION...THE PROBABILITY
OF A FEW THUNDERSTORMS WILL INCREASE MONDAY AFTERNOON AND AGAIN
TUESDAY AFTERNOON.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...WSS/SMITH
SHORT TERM...WSS
LONG TERM...BSD
AVIATION...WSS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
939 PM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 939 PM CDT SAT AUG 17 2013
THE SURFACE TROUGH HAS INCHED EASTWARD...EXTENDING FROM A LOW IN
MANITOBA TO NEAR TIOGA/STANLEY TO NEAR DICKINSON. 00Z SOUNDINGS
INDICATED STRONG CAP IN PLACE AT GLASGOW/BISMARCK/INTERNATIONAL
FALLS AND POINTS SOUTH. STILL MONITORING RADAR AND SATELLITE FOR
ANY EVIDENCE OF CONVECTION...SINCE AFTER SUNSET THE CAP MAY WEAKEN
- ESPECIALLY WITH THE APPROACH/ARRIVAL OF AN UPPER LEVEL
SHORTWAVE.
LOOKING AT WATER VAPOR SAT LOOP...ONE SHORTWAVE IMPULSE IS OVER
SOUTHEASTERN SASKATCHEWAN - POISED TO CATCH UP TO THE SURFACE
TROUGH. SEEING EVIDENCE OF MID CLOUDS IN THE RADAR LOOPS AND SAT
PICS OVER SOUTHEASTERN SASKATCHEWAN TO SOUTHWESTERN MANITOBA. WILL KEEP
MONITORING FOR ANY DEVELOPMENT...AND HENCE HAVE KEPT SLIGHT
CHANCES IN THE NORTH CENTRAL FOR TONIGHT.
A SECOND SHORTWAVE SEEN IN THE WATER VAPOR LOOP WAS APPROACHING
NORTH CENTRAL MONTANA...AND THIS FEATURE IS PROGGED TO MOVE
EASTWARD SLOWLY OVERNIGHT AND ITS LEADING EDGE IS PROGGED TO REACH
NORTHWESTERN NORTH DAKOTA BY DAYBREAK SUNDAY...FOLLOWED BY A
LARGER IMPULSE LATE MORNING/AFTERNOON IN WESTERN NORTH DAKOTA.
MADE MINOR CHANGES TO TEMPERATURES AND WINDS TO REFLECT CURRENT
TRENDS...BUT NO CHANGES IN LOW TEMPERATURES TONIGHT.
UPDATE ISSUED AT 635 PM CDT SAT AUG 17 2013
THE SURFACE TROUGH EXTENDED FROM A LOW IN NORTHERN MANITOBA TO NEAR
TIOGA/WILLISTON TO NEAR BOWMAN. MID-LEVEL CAP IN PLACE WITH H700
THERMAL RIDGE EXTENDING FROM NEAR HETTINGER TO DEVILS LAKE. AT UPPER
LEVELS...A SHORTWAVE WAS MOVING EASTWARD ACROSS SOUTHEASTERN
SASKATCHEWAN INTO SOUTHERN MANITOBA...AND AGITATED CUMULUS/TOWERING
CUMULUS SEEN IN THE VISIBLE SATELLITE PICS HAD BECOME
THUNDERSTORMS ACROSS SOUTHEASTERN SASKATCHEWAN/SOUTHWESTERN
MANITOBA AROUND 5 PM CDT...BUT HAVE SINCE DIMINISHED. BEST 0-6KM
SHEAR IS ACROSS THIS AREA OF SOUTH CENTRAL CANADA. SUSPECT HIGH-
BASED STORMS...AND BEST DOWNDRAFT CAPE AXIS EXTENDS FROM SOUTHERN
MANITOBA TO THE SURFACE TROUGH AREA OF WESTERN NORTH DAKOTA. TIME
WILL TELL LATER THIS EVENING WHETHER THERE IS ENOUGH ENERGY IN THE
UPPER LEVEL SHORTWAVE TO BREAK THE MID-LEVEL CAP IN PLACE - WITH
THE WEAKEST PART OF THE MID-LEVEL CAP ACROSS NORTHERN NORTH
DAKOTA. THUS THE NORTH CENTRAL (BOTTINEAU/MINOT/KENMARE AREAS)
APPEAR TO HAVE THE BEST SHOT AT SEEING CONVECTION IN NORTH DAKOTA.
OTHER THAN THE MINOT AREA...THE NEXT AREA TO WATCH IS ALONG THE
SURFACE TROUGH WHERE LOW LEVEL CONVERGENCE MAY BE ABLE TO LINK
WITH PLENTY OF CAPE ABOVE THE MID-LEVEL CAP AROUND/AFTER SUNSET.
THE ONGOING FORECAST HAD SLIGHT CHANCES IN THE NORTH CENTRAL THIS
EVENING AND SAW NO REASON TO CHANGE THAT AT THIS TIME.
&&
.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 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 635 PM CDT SAT AUG 17 2013
SURFACE TROUGH EXTENDED FROM NEAR KISN/TIOGA TO NEAR BOWMAN. THIS
TROUGH IS PROGGED TO MOVE EASTWARD SLOWLY...TO BE NEAR KMOT TO NEAR
KDIK BY AROUND 03Z...THEN REMAIN NEARLY STATIONARY OVERNIGHT.
SOUTHERLY WINDS EXPECTED AT KJMS THROUGH THE TAF PERIOD...AND MODELS
AGAIN HAVE LOW LEVEL MOISTURE MOVING NORTHWARD INTO THE JAMES RIVER
VALLEY - SO ADDED VCFG FROM 10Z-17Z FOR NOW. SOUTH WINDS AT KBIS
THROUGH AROUND 12Z. VARIABLE WINDS AT OTHER TAF SITES.
UPPER LEVEL DISTURBANCE MOVING EASTWARD ACROSS SOUTHERN
SASKATCHEWAN/MANITOBA. BEST CHANCES OF THUNDERSTORMS IN THIS
AREA...BUT KMOT TO HAVE VCTS FROM 00Z THROUGH 06Z TO ACCOUNT FOR THE
POSSIBILITY OF THE STORMS BUILDING SOUTHWARD.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JV
SHORT TERM...TM
LONG TERM...LTH
AVIATION...JV
AREA FORECAST DISCUSSION
NWS BISMARCK ND
635 PM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 635 PM CDT SAT AUG 17 2013
THE SURFACE TROUGH EXTENDED FROM A LOW IN NORTHERN MANITOBA TO NEAR
TIOGA/WILLISTON TO NEAR BOWMAN. MID-LEVEL CAP IN PLACE WITH H700
THERMAL RIDGE EXTENDING FROM NEAR HETTINGER TO DEVILS LAKE. AT UPPER
LEVELS...A SHORTWAVE WAS MOVING EASTWARD ACROSS SOUTHEASTERN
SASKATCHEWAN INTO SOUTHERN MANITOBA...AND AGITATED CUMULUS/TOWERING
CUMULUS SEEN IN THE VISIBLE SATELLITE PICS HAD BECOME
THUNDERSTORMS ACROSS SOUTHEASTERN SASKATCHEWAN/SOUTHWESTERN
MANITOBA AROUND 5 PM CDT...BUT HAVE SINCE DIMINISHED. BEST 0-6KM
SHEAR IS ACROSS THIS AREA OF SOUTH CENTRAL CANADA. SUSPECT HIGH-
BASED STORMS...AND BEST DOWNDRAFT CAPE AXIS EXTENDS FROM SOUTHERN
MANITOBA TO THE SURFACE TROUGH AREA OF WESTERN NORTH DAKOTA. TIME
WILL TELL LATER THIS EVENING WHETHER THERE IS ENOUGH ENERGY IN THE
UPPER LEVEL SHORTWAVE TO BREAK THE MID-LEVEL CAP IN PLACE - WITH
THE WEAKEST PART OF THE MID-LEVEL CAP ACROSS NORTHERN NORTH
DAKOTA. THUS THE NORTH CENTRAL (BOTTINEAU/MINOT/KENMARE AREAS)
APPEAR TO HAVE THE BEST SHOT AT SEEING CONVECTION IN NORTH DAKOTA.
OTHER THAN THE MINOT AREA...THE NEXT AREA TO WATCH IS ALONG THE
SURFACE TROUGH WHERE LOW LEVEL CONVERGENCE MAY BE ABLE TO LINK
WITH PLENTY OF CAPE ABOVE THE MID-LEVEL CAP AROUND/AFTER SUNSET.
THE ONGOING FORECAST HAD SLIGHT CHANCES IN THE NORTH CENTRAL THIS
EVENING AND SAW NO REASON TO CHANGE THAT AT THIS TIME.
&&
.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 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 635 PM CDT SAT AUG 17 2013
SURFACE TROUGH EXTENDED FROM NEAR KISN/TIOGA TO NEAR BOWMAN. THIS
TROUGH IS PROGGED TO MOVE EASTWARD SLOWLY...TO BE NEAR KMOT TO NEAR
KDIK BY AROUND 03Z...THEN REMAIN NEARLY STATIONARY OVERNIGHT.
SOUTHERLY WINDS EXPECTED AT KJMS THROUGH THE TAF PERIOD...AND MODELS
AGAIN HAVE LOW LEVEL MOISTURE MOVING NORTHWARD INTO THE JAMES RIVER
VALLEY - SO ADDED VCFG FROM 10Z-17Z FOR NOW. SOUTH WINDS AT KBIS
THROUGH AROUND 12Z. VARIABLE WINDS AT OTHER TAF SITES.
UPPER LEVEL DISTURBANCE MOVING EASTWARD ACROSS SOUTHERN
SASKATCHEWAN/MANITOBA. BEST CHANCES OF THUNDERSTORMS IN THIS
AREA...BUT KMOT TO HAVE VCTS FROM 00Z THROUGH 06Z TO ACCOUNT FOR THE
POSSIBILITY OF THE STORMS BUILDING SOUTHWARD.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JV
SHORT TERM...TM
LONG TERM...LTH
AVIATION...JV
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
919 PM EDT SAT AUG 17 2013
.SYNOPSIS...
HIGH PRESSURE OVER NEW ENGLAND WILL REMAIN IN CONTROL OF THE WEATHER
INTO THURSDAY. A WEAK UPPER LEVEL DISTURBANCE WILL PASS TO THE
SOUTHEAST SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
THE HRRR MODEL CAME AROUND AND AGREES WITH THE CURRENT SITUATION
WHERE HIGH CLOUDS CONTINUE TO RACE NORTH INTO THE EASTERN HALF OF
THE FORECAST AREA THIS EVENING. THIS IS IN RESPONSE TO MOISTURE
PLUME RACING NORTH OUT OF THE GULF OF MEXICO AT THIS TIME. UPDATED
GRIDS AND ZONE FORECAST TO REFLECT CLOUD COVER CHANGES IN THE
EASTERN HALF OF THE AREA. EXPECTING SKIES TO REMAIN MOSTLY CLEAR
IN THE WEST HALF OVERNIGHT. SHOULD SEE SOME RETREATING OF CLOUD
COVER TO THE EAST AFTER MIDNIGHT TONIGHT.
NOT EXPECTING TO MAKE ANY MAJOR CHANGES TO THE REST OF THE FIELDS
WITH THIS UPDATE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/...
THE AIR MASS WILL CONTINUE TO WARM A LITTLE MORE EACH DAY SO HIGHS
SUN MOSTLY FROM THE UPPER 70S EAST TO LOWER 80S WEST WILL WARM TO
LOW TO MID 80S FAR EAST TO MID TO UPPER 80S WEST BY WED.
THE WEAK UPPER LEVEL TROF OVER THE LOWER OH RIVER VALLEY SUN WILL
LIFT NE INTO THE CWA BY EARLY MON WHILE WEAKENING THEN SHIFT EAST
THRU TUE. THE MODELS DIFFER ON HOW FAR NW THE DEEPER MOISTURE AND
RAIN THREAT WILL BE PULLED. THINK BEST MOVE MAY BE TO TRY AND
MAINTAIN CONTINUITY AND KEEP MAINLY A SLIGHT CHANCE FOR THE SE SUN
EVE THRU MON.
THE MODELS INDICATE ANOTHER WEAK UPPER TROF DROPPING SE INTO THE
AREA TUE WITH MAYBE SOME ISOLATED CONVECTIVE DEVELOPMENT. ANOTHER
WEAK TROF PROGGED TO BE APPROACHING LERI BY END OF WED NIGHT BUT
SURFACE FRONT STILL LOOKS TO BE FAR ENOUGH TO THE NW TO ALLOW WED
NIGHT TO SAY DRY.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
A WARMER AND MORE HUMID AIR MASS IS EXPECTED WEDNESDAY INTO THURSDAY
AS HIGH PRESSURE PERSISTS OVER THE SOUTHEASTERN US. THERE IS A PIECE
OF JET ENERGY MOVING ACROSS ONTARIO ON THURSDAY THAT WILL PUSH A
WEAK COLD FRONT TOWARD NORTHERN OHIO AND NW PA. THERE MAY BE JUST
ENOUGH CONVERGENCE ALONG A LAKE INDUCED BOUNDARY TO ALLOW FOR A
MENTION OF LATE AFTERNOON AND EVENING THUNDERSTORMS. MODELS THEN
STRUGGLE ON WHAT TO DO FRIDAY INTO SATURDAY. IF THE ECMWF IS CORRECT
WE WILL REMAIN WARM AND HUMID AS THE WEAK FRONTAL BOUNDARY FROM
THURSDAY EVENING LIFTS NORTH AS A WARM FRONT INTO FRIDAY NIGHT.
HAVE LEANED TOWARD THE WARMER ECMWF SOLUTION IN THE EXTENDED WITH
HIGHS WELL INTO THE 80S.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
GENERALLY VFR CONDITIONS WILL PERSIST OVERNIGHT AND THROUGH
SUNDAY ALTHOUGH COULD SEE PATCHY EARLY MORNING FOG/MIST RESULTING
IN MVFR VISIBILITIES AROUND SUNRISE.
OUTLOOK...NON-VFR POSSIBLE IN EARLY MORNING FOG MONDAY THROUGH
THURSDAY.
&&
.MARINE...
HIGH PRESSURE WILL GENERALLY REMAIN TO THE EAST AND SOUTHEAST OF
LAKE ERIE THROUGH TUESDAY. THIS WILL ALLOW ONSHORE FLOW TO DEVELOP
EACH AFTERNOON. OTHERWISE WE WILL WATCH THE HIGH SLOWLY WEAKEN AND
DRIFT FURTHER SOUTH ALLOWING EASTERLY WINDS TO SHIFT TO A SOUTH AND
SOUTHWEST DIRECTION. THIS WIND SHIFT WILL BE IN RESPONSE TO
DEEPENING LOW PRESSURE OVER NORTHERN ONTARIO. WHILE WINDS WONT BE
ALL THAT STRONG THEY WILL INCREASE TO 10 TO 15 KNOTS FROM THE
SOUTHWEST ON WEDNESDAY INTO THURSDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ADAMS
NEAR TERM...LOMBARDY
SHORT TERM...ADAMS
LONG TERM...MULLEN
AVIATION...TK
MARINE...MULLEN
AREA FORECAST DISCUSSION
NWS TULSA OK
1159 PM CDT THU AUG 15 2013
.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
SHOWERS AND THUNDERSTORMS CONTINUE TO PUSH ACROSS PARTS OF
NORTHEAST OKLAHOMA TONIGHT. WILL KEEP PRECIP MENTION AT TUL/RVS.
BROKEN/OVERCAST SKIES SHOULD CONTINUE TONIGHT INTO FRIDAY MORNING
WITH A SCATTERED MID LAYER CLOUD DECK FOR THE AFTERNOON/EVENING
HOURS. WINDS ARE EXPECTED TO BE BREEZY AND VARIABLE WITH THE MCS
TONIGHT OTHERWISE LIGHT OUT OF THE EAST TO SOUTHEAST. VFR
CONDITIONS SHOULD PERSIST...WITH POSSIBLE MVFR CONDITIONS WITHIN
THE MCS OVER NORTHEAST OKLAHOMA.
&&
.PREV DISCUSSION... /ISSUED 902 PM CDT THU AUG 15 2013/
DISCUSSION...
MCS OVER SOUTH CENTRAL KANSAS IS ABOUT TO PUSH INTO NORTHERN
OKLAHOMA THIS EVENING. THE SYSTEM IS NO LONGER SEVERE...WITH THE
STRONGEST MEASURED WIND OVER THE PAST HOUR OR SO AT 35 MPH. THE
PRIMARY MECHANISM DRIVING THIS SYSTEM IS THE COLD POOL LIFTING
MODERATELY UNSTABLE AIR ON THE ORDER OF 1000-2000 J/KG OF
MLCAPE...AND THIS INSTABILITY IS PRIMARILY CONFINED WEST OF
HIGHWAY 75. AN 850MB RIDGE RESIDES OVER EASTERN OKLAHOMA...SO
THERE IS NOT THAT TYPICAL LOW LVL JET FEEDING INTO THIS SYSTEM.
THEREFORE...THE MCS WILL CONTINUE SOUTH...MAINLY TO THE WEST OF
HIGHWAY 75 WHERE THE INSTABILITY IS...AND LIKELY WEAKEN WITH TIME AS
WE GO INTO THE NIGHT AS THE HRRR MODEL SUGGESTS. UPDATED PRODUCTS
HAVE BEEN SENT.
LACY
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 63 84 62 87 / 40 20 0 0
FSM 62 85 62 89 / 10 10 0 0
MLC 62 84 61 89 / 20 20 10 10
BVO 61 82 59 85 / 60 20 0 0
FYV 54 81 55 83 / 10 10 0 0
BYV 56 79 57 82 / 0 10 10 10
MKO 60 84 61 87 / 20 20 0 0
MIO 59 81 58 83 / 20 10 0 0
F10 62 83 62 87 / 30 20 10 0
HHW 62 87 63 89 / 10 20 10 0
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
AVIATION...20
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1044 PM EDT SAT AUG 17 2013
.SYNOPSIS...
A WEDGE OF COOL HIGH PRESSURE WILL REMAIN IN PLACE OVER THE
CAROLINAS THROUGH THE WEEKEND...THEN GRADUALLY WEAKEN EARLY NEXT
WEEK. MEANWHILE A SERIES OF LOWS WILL RIDE UP ALONG A STATIONARY
FRONTAL BOUNDARY LOCATED ALONG THE CAROLINA COAST BRINGING MOIST
TROPICAL AIR INTO THE SOUTHEAST. THIS WILL GENERATE WIDESPREAD
SHOWERS ACROSS THE AREA THROUGH THE FIRST PART OF THE WEEK. DRIER
AND WARMER WEATHER IS EXPECTED TO RETURN BY THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH SUNDAY/...
AS OF 1045 PM EDT SATURDAY...SEVERAL BANDS OF SCATTERED SHOWERS
CONTINUE TO PUSH NORTHWARD ACROSS THE REGION WITH THE HEAVIEST RAIN
CURRENTLY FALLING ACROSS THE NORTH CAROLINA PIEDMONT. AS FOR SKY
COVER...MOST LOCATIONS ARE SEEING LOW STRATUS AS THE MOIST BOUNDARY
LAYER SETTLES...WHILE OTHER LOCATIONS ARE SEEING A MIXTURE OF
LOW/MID LEVEL STRATUS. LATEST NAM AND HRRR GUIDANCE LINE UP
WELL WITH THE POP TREND IN THE FORECAST. HOWEVER...DID MAKE A FEW
CHANGES TO THE NEAR TERM POP GRIDS TO ACCOUNT FOR HEAVIER SHOWERS
ACROSS THE NC PIEDMONT AND FURTHER SOUTH INTO THE NORTHEAST GA
MOUNTAINS. OTHERWISE...DID NOT MAKE ANY SIGNIFICANT CHANGES OTHER
THAN ADJUSTING TEMPERATURE AND DEWPOINT TRENDS TO REFLECT LATEST
OBSERVATIONS.
PREVIOUS DISCUSSION...
AS OF 245 PM...CWFA REMAINS IN THE DEEP SLY FLOW BETWEEN UPPER LOW
NEAR THE JUNCTION OF THE OH AND MS RIVERS AND THE BERMUDA ANTI-
CYCLONE. A SERIES OF WAVES WILL MOVE THRU THIS FLOW ALONG WITH A
SERIES OF JET STREAKS PROVIDING SYNOPTIC SCALE LIFT AND UPPER
DIVERGENCE. THIS FLOW ALSO KEEPS A PLUME OF TROPICAL MOISTURE OVER
THE CWFA. PW VALUES ARE NEAR 2 INCHES WHICH IS HIGH...BUT NOT
EXCESSIVELY SO. ISENTROPIC LIFT WILL CONTINUE TO INCREASE ACROSS THE
AREA INTO THE EARLY EVENING BRINGING WIDESPREAD RAINFALL BACK ACROSS
THE AREA. WITH THE FORCING AND PW VALUES...EXPECT MODERATE RAINFALL
AMOUNTS FOR BASIN AVERAGES. CANNOT RULE OUT SOME HEAVY RAINFALL
ADDING UP AFTER A SERIES OF MODERATE RAIN LEADING TO SOME HIGH WATER
LEVELS. HOWEVER...THE THREAT OF ANY WIDESPREAD HEAVY RAINFALL AND/OR
FLOODING IS QUITE LOW. THE BEST ISENTROPIC LIFT MOVES OFF THE THE
NORTH OVERNIGHT AS LOW LEVEL FLOW BECOMES MORE SWLY...AND BEST
FORCING RETREATS TO THE WEST. HOWEVER...LOW LEVEL MOISTURE REMAINS
QUITE HIGH. THEREFORE... EXPECT WIDESPREAD RAINFALL TO DIMINISH WITH
BEST CHC LINGERING OVER THE MTNS. AREAS OF FOG SHUD DEVELOP TOWARD
MORNING AND COULD BECOME DENSE IN AREAS...ESPECIALLY IF WEDGE BEGINS
TO ERODE. LOWS WILL BE A FEW DEGREES BELOW NORMAL.
SUNDAY...UPPER LOW BEGINS TO OPEN UP AND MOVE NORTHEAST THRU THE OH
VALLEY AS THE RIDGING BEGINS TO MOVE IN FROM THE EAST. THIS HELPS
TURN THE FLOW MORE SWLY ENDING THE THREAT OF STRONG ISENTROPIC LIFT
OVER THE AREA. THIS MAY ALSO HELP ERODE THE LOW LEVEL CAD INVERSION
ALLOWING A WEAK SWLY SFC FLOW TO DEVELOP. THIS SHOULD ALLOW THE LOW
LEVELS TO DRY SLIGHTLY CREATING A BREAK IN THE LOW CLOUDS AND SOME
HEATING TO DEVELOP. THIS SHUD ALSO LEAD TO WEAK INSTABILITY DURING
THE AFTERNOON. AGAIN...BEST PRECIP CHC WILL BE OVER THE WEST WHERE
MOISTURE AND FORCING ARE HIGHEST AND IMPINGING RIDGE HAS LESS
INFLUENCE. WITHOUT THE CONTINUATION OF NELY WINDS...LOW CLOUDS AND
STEADY PRECIP...TEMPS WILL BE ABLE TO RISE THRU THE DAY. IN FACT...
LOW LEVEL THICKNESSES WILL BE HIGHER. ANY SUNSHINE WOULD ALLOW A
QUICK RISE IN TEMPS. HOWEVER...EXPECT THERE WILL BE ENUF CLOUDS...
EVEN WITH LOW CLOUDS ERODING...TO RETARD SIGNIFICANT HEATING. THAT
SAID...EXPECT HAVE GONE WITH THE BIAS CORRECTED MOS WHICH IS COOLER
BUT STILL ALLOWS TEMPS TO RISE INTO THE 70S ACROSS THE AREA.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
AS OF 245 PM EDT SATURDAY...A CLOSED UPPER LOW OVER THE WEST WILL
OPEN UP AS IT LEFTS NE ACROSS THE OHIO VALLEY SUN NIGHT INTO MONDAY.
A LOW AMPLITUDE UPPER RIDGE OF HIGH WILL BUILD SOUTH OF THE CWA
TUESDAY WITH A SERIES OF UPPER DISTURBANCES RIPPLING THROUGH THE
REGION IN WEAK WESTERLY FLOW ALOFT.
AT THE SURFACE...THE LATEST NAM HAS TRENDED A BIT FASTER WITH THE
EROSION OF THE COOL AIR WEDGE BY SUN NIGHT WHILE THE GFS KEEPS THE
WEDGE AT LEAST THROUGH MIDDAY MONDAY. NONETHELESS...WE WILL SEE
RETURN SOUTHERLY FLOW BY MONDAY AFTERNOON AS THE HIGH SHIFTS
OFFSHORE AND CONTINUES TO RIDGE INTO THE REGION. THE HIGH WILL
REMAIN CENTERED OFFSHORE TUESDAY WITH CONTINUED SE FLOW REGIME OVER
THE CWA. IN RESPONSE TO THE RETURN FLOW...MODEL SOUNDINGS INDICATE
THAT SBCAPE VALUES WILL BE AROUND 700-1500J/KG WITH PW VALUES
REACHING 2 INCHES BOTH MON AND TUE AFTERNOON. IN ADDITION...THE
MAGNITUDE OF THE MBE VELOCITY WILL BE LESS THAN 10 KTS MEANING
STORMS WILL MOVE SLOWLY. SO LOCALIZED FLASH FLOODING CAN NOT BE
RULED OUT. TEMPERATURES WILL WARM UP INTO THE LOWER 80S EAST OF THE
MOUNTAINS BY MONDAY BUT STILL WE ARE LOOKING AT AROUND 3-5 DEGREES
BELOW NORMAL VALUES.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM EDT SATURDAY...THE GLOBAL MODELS AGREE THAT AN UPPER
RIDGE WILL PREVAIL OVER THE SE STATES TUE NIGHT INTO THU BEFORE
BECOMING NORTHERLY FLOW ALOFT BY FRI AS AN UPPER TROUGH OVER THE
SOUTH-CENTRAL CANADA DIGS DOWN INTO THE MID ATLANTIC STATES. THE
UPPER FLOW WILL REMAIN NORTHERLY OVER THE REGION THROUGH THE END OF
THE MEDIUM RANGE PERIOD AS A BROAD UPPER RIDGE OF H5 HIGH REMAINS
ANCHORED OVER THE CENTRAL CONUS.
AT THE SURFACE...MOIST SE FLOW WILL PREVAIL TUE NIGHT INTO FRIDAY AS
THE BERMUDA HIGH PRESSURE CONTINUES TO RIDGE INTO THE CWA. MODEL
SOUNDINGS INDICATE THAT ATMOS WILL BE GENERALLY UNCAPPED WITH SBCAPE
VALUES RANGING FROM 1000 TO 2000J/KG ON EACH AFTERNOON. HENCE I HAVE
MENTIONED DIURNAL 30-40 PERCENT POPS DURING THIS PERIOD. BY FRI
NIGHT...THE LATEST 12Z GFS INDICATES THE BERMUDA HIGH WILL WEAKEN
AND SHIFT EAST OF THE AREA AS ANOTHER HIGH PRESSURE CENTERED OVER
THE GREAT LAKES REGION GRADUALLY RIDGES DOWN INTO THE SE STATES.
MEANWHILE...THE 00Z ECMWF KEEPS THE BERMUDA HIGH OVER THE REGION
THROUGH THE END OF THE MEDIUM RANGE PERIOD. GIVEN THE
UNCERTAINTY..HAVE CARRIED LOWER POPS ON SAT. TEMPERATURES WILL
REMAIN A FEW DEGREES BELOW NORMAL THRU THE PERIOD.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
AT KCLT...EXPECTING SCATTERED RA TO CONTINUE ACROSS THE NC PIEDMONT
THROUGH THE FIRST FEW HOURS OF THE PERIOD WITH IFR CONDITIONS
PREVAILING. CIGS ARE FORECAST TO LOWER TO LIFR LEVELS DURING THE
OVERNIGHT HOURS AS SHOWERS DIMINISH AND THE SATURATED BOUNDARY
LAYER SETTLES. CONDITIONS WILL IMPROVE NEAR DAYBREAK AS IFR CIGS
RETURN BEFORE GIVING WAY TO MVFR CIGS BY AROUND 15Z. BEYOND
THAT...SUNDAY AFTERNOON LOOKS TO HAVE NO RESTRICTIONS WITH THE
EXCEPTION OF A SLIGHT CHANCE OF SCATTERED TSRA WITH 4SM VISB.
OTHERWISE...WINDS WILL REMAIN LIGHT AND NORTHEASTERLY DURING THE
OVERNIGHT HOURS AND INTO THE MID/LATE MORNING BEFORE SHIFTING
SOUTHERLY AS THE HIGH PRESSURE WEDGES ERODES.
ELSEWHERE...A MIXTURE OF MVFR/IFR TO EVEN LIFR CONDITIONS WILL
HIGHLIGHT THE TAF PERIOD. RA WILL PERSIST THROUGH THE EARLY MORNING
HOURS AT ALL SITES CAUSING CIGS TO REMAIN AT IFR LEVELS. AFTERWORDS
EXPECTING CIGS TO LOWER TO LIFR LEVELS AT ALL SITES AS THE BOUNDARY
LAYER SETTLES. THE MORE MOUNTAINOUS SITES WILL SEE A POSSIBILITY
FOR SOME FOG DEVELOPMENT BY MID MORNING. CONDITIONS WILL SLOWLY
IMPROVE TO IFR THEN TO MVFR BY THE LATE MORNING HOURS BEFORE
EVENTUALLY GIVING WAY TO LOW END VFR. KAVL WILL LIKELY SEE SHOWERS
PERSIST THROUGH THE PERIOD AS THE MOISTURE AXIS CONTINUES TO SHIFT
WESTWARD. RAIN CHANCES DIMINISH SOMEWHAT FOR OTHER LOCATIONS THUS
PREVAILED VCSH LATE IN THE PERIOD EXCEPT FOR KHKY WHERE WENT WITH A
PROB30 FOR AFTERNOON TSRA. WINDS WILL REMAIN NORTHEASTERLY THROUGH
THE FIRST HALF OF THE TAF CYCLE BEFORE SHIFTING SOUTHERLY LATE
SUNDAY MORNING.
OUTLOOK...SOME IMPROVEMENT TO MOSTLY VFR EXPECTED EARLY NEXT WEEK.
SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS WILL LIKELY CAUSE
RESTRICTIONS BY MID TO LATE WEEK AS DIURNAL EFFECTS DOMINATE.
CONFIDENCE TABLE...
02-08Z 08-14Z 14-20Z 20-02Z
KCLT HIGH 80% HIGH 90% HIGH 91% HIGH 100%
KGSP HIGH 89% MED 77% HIGH 86% HIGH 100%
KAVL HIGH 90% HIGH 90% HIGH 86% HIGH 85%
KHKY HIGH 100% HIGH 92% HIGH 83% HIGH 81%
KGMU HIGH 86% HIGH 84% HIGH 86% HIGH 100%
KAND MED 75% HIGH 86% HIGH 84% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PAT
NEAR TERM...CDG/RWH
SHORT TERM...JOH
LONG TERM...JOH
AVIATION...CDG
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
703 AM EDT FRI AUG 16 2013
.SYNOPSIS...
A WEDGE OF COOL HIGH PRESSURE WILL REMAIN IN PLACE OVER THE
CAROLINAS THROUGH THE WEEKEND...THEN GRADUALLY WEAKEN EARLY NEXT
WEEK. A STRONG UPPER TROUGH DEVELOPING OVER THE MISSISSIPPI VALLEY
WILL BRING TROPICAL MOISTURE OVER THE HIGH PRESSURE WEDGE TODAY AND
OVER THE WEEKEND...BRINGING WIDESPREAD SHOWERS TO THE AREA. DRIER
AND WARMER WEATHER IS EXPECTED TO RETURN BY THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 530 AM...RAIN RATES WITHIN BLOSSOMING AREA OF PRECIP IS A BIT
SURPRISING AS IT ENTERS OUR SRN COUNTIES...WITH POCKETS OF 1-2"/HR
INSTANTANEOUS RATES ON DUAL POL. THE LATEST MESOSCALE GUIDANCE...6Z
NAM...AND THE RAP ALL AGREE ON THIS PRECIP SHIELD EXPANDING AND
STREAKING NEWD ACRS ZONES ALONG AND SOUTH OF I-85 THIS MORNING. I
HAVE BUMPED POPS UP TO CATEGORICAL...AND TWEAKED THE QPF UP WHERE
THIS RAIN SHIELD GOES. TRENDS ALSO SUGGEST THAT THE I-40 CORRIDOR
WILL HAVE A DRIER MORNING THAN FCST...SO I CUT BACK POP THERE.
OTHERWISE...FCST ON TRACK.
AS OF 300 AM...A POTENT LOBE OF VORTICITY WILL ROUND THE BASE OF AN
UPR LONGWAVE TROF AXIS INVOF THE MID SOUTH EARLY THIS MORNING...THEN
CROSS THE TN VLY TO OUR CWFA THIS AFTN/EVE. THE WAVE WILL PROVIDE
MID-UPR FORCING WHICH WILL BE COUPLED WITH INCREASING LLVL LIFT
ALONG A STALLED FRONTAL BNDRY DRAPED ACRS THE SOUTHEAST STATES. A
WEAK WAVE IS PROGGED TO FORM ON A 850 MB FRONTAL ZONE INVOF
AL...INCREASING THE LLVL S/SELY FLOW ATOP A COLD AIR DAMMING WEDGE.
MODELS ARE IN DECENT AGREEMENT ON THIS SETUP...BUT FOR SOME REASON
STILL DIFFER GREATLY ON THE EXACT PLACEMENT/TIMING/MAGNITUDE OF QPF
THRU TONIGHT (AND THRU THE WEEKEND). THE NAM CONTINUES TO BE AN
OUTLIER ON A BULLSEYE OF 2-2.5" ACRS THE UPSTATE AND NE GA BY 00Z
THIS EVENING. THE NAM CONTINUES THE HIGH QPF RESPONSE INTO THE NC
PIEDMONT/FOOTHILLS TONIGHT. THE OTHER OP GUIDANCE IS A LTL MORE IN
LINE WITH GFS...HAVING LOWER MAGNITUDE...AND KEEPING THE HEAVIEST
RAIN TO OUR SOUTHEAST CLOSER TO THE SFC FRONT. I THINK THIS MAKES
SENSE...AS THE BEST PWATS/MOISTURE FLUX AND UPR DIVERGENCE WILL BE
THERE.
SO THE FCST FOR TODAY IS FOR RAIN/SHWRS TO SPREAD IN FROM THE
SOUTH...WITH GREATEST COVERAGE REMAINING ACRS ALONG AND SOUTH OF
I-85. THE RAIN AND CLOUDS SHUD LOCK IN UNSEASONABLY COOL TEMPS FOR
THE DAY...AS WEDGE BECOMES DIABATICALLY ENHANCED. A CONSENSUS BLEND
RESULTS IN MAX TEMPS 15-20 DEG BELOW NORMAL. TEMPS MAY STRUGGLE TO
REACH 70 ACRS PORTIONS OF THE UPSTATE AND SRN NC PIEDMONT...IF RAIN
IS HEAVIER AND/OR MORE PERSISTENT THAN EXPECTED.
TONIGHT...TIMING DIFFERENCES ALREADY MAKE FOR UNCERTAINTY IN THE
HOURLY POP TRENDS. IT SEEMS THERE MAY BE A RELATIVE LULL IN ACTIVITY
THIS EVENING...AS ONE WAVE PASSES BY. HOWEVER...THE UPR TROF WILL
CONTINUE TO AMPLIFY...WITH ANOTHER ROUND OF STRONGER QG FORCING AND
BETTER ISENT LIFT DEVELOPING OVERNIGHT. HAVE POPS RAMPING BACK UP TO
CATEGORICAL IN THE EAST. AGAIN...QPF IS EXPECTED TO BE SOAKING...BUT
NOT EXCESSIVE. I WENT CLOSE TO WPC FOR ALL THE 6-HOURLY QPF GRIDS IN
THE NEAR TERM.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 220 AM FRIDAY...THE SHORT TERM FCST PICKS UP AT 12Z ON
SATURDAY WITH GUIDANCE IN FAIRLY GOOD AGREEMENT ON AN UPPER LOW
DEVELOPING OVER THE MID SOUTH BY EARLY SAT. THIS LOW REMAINS NEARLY
STATIONARY SAT NITE WITH A SLIGHT NORTHEASTWARD DRIFT ON SUN AND
THEN LIFTING ON SUN NIGHT AND INTO MON. AT THE SFC...THE FCST AREA
WILL REMAIN UNDER THE COOL AIR WEDGE THRU THE END OF THE PERIOD
EARLY MON. THERE ARE SOME NOTABLE DISCREPANCIES BETWEEN THE
OPERATIONAL MODELS WRT HOW QUICKLY THE WEDGE DISSIPATES WITH THE GFS
TRYING TO MAINTAIN THE FEATURE LONGER THAN THE NAM AND ECMWF.
REGARDLESS...AS WE MOVE INTO THE MEDIUM RANGE THE BERMUDA SFC HIGH
WILL REESTABLISH ITSELF AND BRING SLY LOW LVL FLOW BACK TO THE
REGION. WITH THAT SAID...POPS WILL BE HIGH OVER MOST OF THE CWFA
THRU SUN EVENING AS FAVORABLE ISENTROPIC LIFT AND HIGH PWAT VALUES
PERSIST. BY EARLY MONDAY...LIKELY POPS WILL SHIFT TO THE EAST AS THE
BEST UPPER LVL SUPPORT MOVES TOWARDS THE COAST. GUIDANCE BLEND
CONTINUES TO SUGGEST MODERATE QPF AMOUNTS AT BEST WITH MINIMAL
INSTABILITY THRU SUN. I KEPT TEMPS WELL BELOW CLIMO WITH VALUES
STEADILY RISING EACH DAY. BY MON...WE ARE BACK IN THE LOW 80S OVER
THE UPSTATE AND PIEDMONT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 2 AM FRIDAY...THE MEDIUM RANGE FCST PICKS UP AT 12Z ON MONDAY
WITH THE UPPER LEVEL TROUGH ERODING AND SHIFTING EASTWARD. THE COOL
WEDGE WILL GRADUALLY DISSIPATE BY THE MIDDLE OF NEXT WEEK...AS A
SURFACE HIGH BUILDS IN OVER THE CWA AND AN UPPER RIDGE GRADUALLY
SLIDES EASTWARD ACROSS THE CONUS. THIS LENDS ITSELF TO A DRIER
PERIOD...WITH A RETURN TO NORMAL SUMMERTIME DIURNAL POPS FOR THE
MIDDLE AND END OF NEXT WEEK. THE DRYING TREND WILL ALLOW
TEMPERATURES TO INCREASE BACK TO THE LOW TO MID 80S BY THE MIDDLE OF
NEXT WEEK...THOUGH HIGHS WILL STILL REMAIN A FEW DEGREES BELOW
NORMAL.
&&
.AVIATION /11Z FRIDAY THROUGH TUESDAY/...
AT KCLT...CONDITIONS HAVE BEEN TRENDING A LITTLE MORE PESSIMISTIC
SINCE THE 06Z TAFS. A RAIN SHIELD HAS SPREAD ACRS THE UPSTATE AND
WILL AFFECT THE KCLT TERMINAL THIS MORNING. RAIN RATES ARE EXPECTED
TO BE ON THE LIGHT SIDE...BUT BRIEF MVFR VSBY OR CIG RESTRICTIONS
WHEN THE RAIN MOVES THRU CANNOT BE RULED OUT. CIGS SHUD LWR TO 4000
FT BY ABOUT 14Z...THEN BEGIN TO LOWER TOWARD MVFR THIS AFTN.
GUIDANCE IS VERY DIVERGENT ON THE CIG TRENDS...SO CONFIDENCE IS LOW
ON WHEN THINGS REALLY START TO DETERIORATE. AFTER
SUNSET...CONFIDENCE INCREASES THAT LOW CIGS WILL BECOME
PERSISTENT...AS MORE SHRA MOVE INTO THE AREA. WINDS WILL REMAIN NE
OR ENE...AND INCREASE TO 8-10 KTS BY LATE MORNING.
ELSEWHERE...RAIN IS SPREADING INTO THE UPSTATE SITES BY THE TIME THE
12Z TAFS BECOME VALID. THE RAIN IS LIGHT SO FAR...BUT RESTRICTIONS
IN VSBY AND/OR CIGS ARE POSSIBLE. THE RAIN WILL TAPER OFF SOMEWHAT
BY EARLY AFTN...WITH GUIDANCE RATHER DIVERGENT ON WHETHER CIGS
IMPROVE OR CONTINUE TO LINGER IN THE MVFR RANGE. WENT WITH A
COMPROMISE FOR THE CIG TRENDS. TONIGHT...MOISTURE INCREASES AND CIGS
ARE EXPECTED TO LOWER TO IFR BY THE END OF THE TAF PERIOD. FOR KAVL
AND KHKY...TRENDS WILL BE SLOWER...AS MORE DRY AIR AND LESS PRECIP
EXPECTED TODAY. WINDS WILL OUT OF THE NE (EXCEPT SE AT KAVL)...AND
GENERALLY UNDER 10 KTS.
OUTLOOK...A STATIONARY FRONT IS EXPECTED TO REMAIN SOUTH AND EAST OF
THE FORECAST AREA THROUGH THE WEEKEND...KEEPING THE AREA IN A COOL
MOIST WEDGE OF HIGH PRES. RESTRICTIVE CIGS AND VSBYS WILL LIKELY
PERSIST ACRS THE REGION THRU AT LEAST SUNDAY...THEN SOME IMPROVEMENT
TO MOSTLY VFR EXPECTED EARLY NEXT WEEK...AS THE WEDGE ERODES.
CONFIDENCE TABLE...
11-17Z 17-23Z 23-05Z 05-11Z
KCLT MED 77% HIGH 91% MED 79% HIGH 91%
KGSP MED 79% HIGH 80% HIGH 91% HIGH 95%
KAVL HIGH 87% HIGH 100% HIGH 89% HIGH 95%
KHKY HIGH 100% HIGH 100% HIGH 91% HIGH 94%
KGMU MED 73% MED 77% HIGH 90% HIGH 97%
KAND MED 63% HIGH 83% HIGH 93% HIGH 91%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.CLIMATE...
RECORD LOW MAX TEMPERATURES THIS WEEKEND...
AUG 16 AUG 17 AUG 18
AVL...62 1964 72 1986 70 1905
CLT...64 1964 71 1992 72 1894
GSP...64 1964 71 1971 71 1957
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...ARK
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...ARK
CLIMATE...
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
539 AM EDT FRI AUG 16 2013
.SYNOPSIS...
A WEDGE OF COOL HIGH PRESSURE WILL REMAIN IN PLACE OVER THE
CAROLINAS THROUGH THE WEEKEND...THEN GRADUALLY WEAKEN EARLY NEXT
WEEK. A STRONG UPPER TROUGH DEVELOPING OVER THE MISSISSIPPI VALLEY
WILL BRING TROPICAL MOISTURE OVER THE HIGH PRESSURE WEDGE TODAY AND
OVER THE WEEKEND...BRINGING WIDESPREAD SHOWERS TO THE AREA. DRIER
AND WARMER WEATHER IS EXPECTED TO RETURN BY THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 530 AM...RAIN RATES WITHIN BLOSSOMING AREA OF PRECIP IS A BIT
SURPRISING AS IT ENTERS OUR SRN COUNTIES...WITH POCKETS OF 1-2"/HR
INSTANTANEOUS RATES ON DUAL POL. THE LATEST MESOSCALE GUIDANCE...6Z
NAM...AND THE RAP ALL AGREE ON THIS PRECIP SHIELD EXPANDING AND
STREAKING NEWD ACRS ZONES ALONG AND SOUTH OF I-85 THIS MORNING. I
HAVE BUMPED POPS UP TO CATEGORICAL...AND TWEAKED THE QPF UP WHERE
THIS RAIN SHIELD GOES. TRENDS ALSO SUGGEST THAT THE I-40 CORRIDOR
WILL HAVE A DRIER MORNING THAN FCST...SO I CUT BACK POP THERE.
OTHERWISE...FCST ON TRACK.
AS OF 300 AM...A POTENT LOBE OF VORTICITY WILL ROUND THE BASE OF AN
UPR LONGWAVE TROF AXIS INVOF THE MID SOUTH EARLY THIS MORNING...THEN
CROSS THE TN VLY TO OUR CWFA THIS AFTN/EVE. THE WAVE WILL PROVIDE
MID-UPR FORCING WHICH WILL BE COUPLED WITH INCREASING LLVL LIFT
ALONG A STALLED FRONTAL BNDRY DRAPED ACRS THE SOUTHEAST STATES. A
WEAK WAVE IS PROGGED TO FORM ON A 850 MB FRONTAL ZONE INVOF
AL...INCREASING THE LLVL S/SELY FLOW ATOP A COLD AIR DAMMING WEDGE.
MODELS ARE IN DECENT AGREEMENT ON THIS SETUP...BUT FOR SOME REASON
STILL DIFFER GREATLY ON THE EXACT PLACEMENT/TIMING/MAGNITUDE OF QPF
THRU TONIGHT (AND THRU THE WEEKEND). THE NAM CONTINUES TO BE AN
OUTLIER ON A BULLSEYE OF 2-2.5" ACRS THE UPSTATE AND NE GA BY 00Z
THIS EVENING. THE NAM CONTINUES THE HIGH QPF RESPONSE INTO THE NC
PIEDMONT/FOOTHILLS TONIGHT. THE OTHER OP GUIDANCE IS A LTL MORE IN
LINE WITH GFS...HAVING LOWER MAGNITUDE...AND KEEPING THE HEAVIEST
RAIN TO OUR SOUTHEAST CLOSER TO THE SFC FRONT. I THINK THIS MAKES
SENSE...AS THE BEST PWATS/MOISTURE FLUX AND UPR DIVERGENCE WILL BE
THERE.
SO THE FCST FOR TODAY IS FOR RAIN/SHWRS TO SPREAD IN FROM THE
SOUTH...WITH GREATEST COVERAGE REMAINING ACRS ALONG AND SOUTH OF
I-85. THE RAIN AND CLOUDS SHUD LOCK IN UNSEASONABLY COOL TEMPS FOR
THE DAY...AS WEDGE BECOMES DIABATICALLY ENHANCED. A CONSENSUS BLEND
RESULTS IN MAX TEMPS 15-20 DEG BELOW NORMAL. TEMPS MAY STRUGGLE TO
REACH 70 ACRS PORTIONS OF THE UPSTATE AND SRN NC PIEDMONT...IF RAIN
IS HEAVIER AND/OR MORE PERSISTENT THAN EXPECTED.
TONIGHT...TIMING DIFFERENCES ALREADY MAKE FOR UNCERTAINTY IN THE
HOURLY POP TRENDS. IT SEEMS THERE MAY BE A RELATIVE LULL IN ACTIVITY
THIS EVENING...AS ONE WAVE PASSES BY. HOWEVER...THE UPR TROF WILL
CONTINUE TO AMPLIFY...WITH ANOTHER ROUND OF STRONGER QG FORCING AND
BETTER ISENT LIFT DEVELOPING OVERNIGHT. HAVE POPS RAMPING BACK UP TO
CATEGORICAL IN THE EAST. AGAIN...QPF IS EXPECTED TO BE SOAKING...BUT
NOT EXCESSIVE. I WENT CLOSE TO WPC FOR ALL THE 6-HOURLY QPF GRIDS IN
THE NEAR TERM.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 220 AM FRIDAY...THE SHORT TERM FCST PICKS UP AT 12Z ON
SATURDAY WITH GUIDANCE IN FAIRLY GOOD AGREEMENT ON AN UPPER LOW
DEVELOPING OVER THE MID SOUTH BY EARLY SAT. THIS LOW REMAINS NEARLY
STATIONARY SAT NITE WITH A SLIGHT NORTHEASTWARD DRIFT ON SUN AND
THEN LIFTING ON SUN NIGHT AND INTO MON. AT THE SFC...THE FCST AREA
WILL REMAIN UNDER THE COOL AIR WEDGE THRU THE END OF THE PERIOD
EARLY MON. THERE ARE SOME NOTABLE DISCREPANCIES BETWEEN THE
OPERATIONAL MODELS WRT HOW QUICKLY THE WEDGE DISSIPATES WITH THE GFS
TRYING TO MAINTAIN THE FEATURE LONGER THAN THE NAM AND ECMWF.
REGARDLESS...AS WE MOVE INTO THE MEDIUM RANGE THE BERMUDA SFC HIGH
WILL REESTABLISH ITSELF AND BRING SLY LOW LVL FLOW BACK TO THE
REGION. WITH THAT SAID...POPS WILL BE HIGH OVER MOST OF THE CWFA
THRU SUN EVENING AS FAVORABLE ISENTROPIC LIFT AND HIGH PWAT VALUES
PERSIST. BY EARLY MONDAY...LIKELY POPS WILL SHIFT TO THE EAST AS THE
BEST UPPER LVL SUPPORT MOVES TOWARDS THE COAST. GUIDANCE BLEND
CONTINUES TO SUGGEST MODERATE QPF AMOUNTS AT BEST WITH MINIMAL
INSTABILITY THRU SUN. I KEPT TEMPS WELL BELOW CLIMO WITH VALUES
STEADILY RISING EACH DAY. BY MON...WE ARE BACK IN THE LOW 80S OVER
THE UPSTATE AND PIEDMONT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 2 AM FRIDAY...THE MEDIUM RANGE FCST PICKS UP AT 12Z ON MONDAY
WITH THE UPPER LEVEL TROUGH ERODING AND SHIFTING EASTWARD. THE COOL
WEDGE WILL GRADUALLY DISSIPATE BY THE MIDDLE OF NEXT WEEK...AS A
SURFACE HIGH BUILDS IN OVER THE CWA AND AN UPPER RIDGE GRADUALLY
SLIDES EASTWARD ACROSS THE CONUS. THIS LENDS ITSELF TO A DRIER
PERIOD...WITH A RETURN TO NORMAL SUMMERTIME DIURNAL POPS FOR THE
MIDDLE AND END OF NEXT WEEK. THE DRYING TREND WILL ALLOW
TEMPERATURES TO INCREASE BACK TO THE LOW TO MID 80S BY THE MIDDLE OF
NEXT WEEK...THOUGH HIGHS WILL STILL REMAIN A FEW DEGREES BELOW
NORMAL.
&&
.AVIATION /10Z FRIDAY THROUGH TUESDAY/...
AT KCLT...AN ABOVE AVERAGE AMOUNT OF UNCERTAINTY IN THE TRENDS WITH
THIS TAF...AS MOISTURE AND LIFT ARE EXPECTED TO INCREASE ATOP A COLD
AIR DAMMING WEDGE...WITH NUMEROUS TO WIDESPREAD SHRA OR MORE OF A
STRATIFORM PRECIP SHIELD DEVELOPING ACRS THE AREA BY DAYBREAK.
DESPITE HIGH POPS...GUIDANCE IS RELATIVELY OPTIMISTIC...WITH
GENERALLY VFR LVL CLOUDS THRUT MOST OF THE DAY. WITH THAT
SAID...THERE WILL BE A GRADIENT IN THE CIGS FROM SE TO NW...AND KCLT
MAY LEVEL OFF IN THE MVFR RANGE. BUT GOING WITH A CONSENSUS OF THE
GUIDANCE...I HAVE VFR THRU THE AFTN. SHRA COVERAGE WILL PROBABLY BE
GREATEST DURING THE MIDDAY HOURS...THEN PERHAPS A RELATIVE LULL IN
THE EVENING BEFORE ANOTHER ROUND TONIGHT. WINDS WILL STAY NELY THRU
THE PERIOD...GENERALLY 5-10 KTS.
ELSEWHERE...THE AREA IS STARTING OUT WITH INCREASING MID CLOUDS
(8-10 KFT)...BUT A LOWER VFR DECK SHUD DEVELOP AND SHRA SHUD BREAK
OUT...ESP ACRS THE UPSTATE AND ACRS THE NC MTNS BY DAYBREAK. CIGS
WILL LIKELY DROP TO MVFR ACRS THE LWR PIEDMONT...WITH KAND THE MOST
LIKELY TO STAY AT THAT LEVEL. MORE UNCERTAIN FOR KGSP/KGMU. KHKY IS
EXPECTED TO STAY VFR UNTIL THIS EVENING. KAVL ALSO IS A LOW
CONFIDENCE FCST...AND MAY BE IN AND OUT OF MVFR THRUT THE DAY DUE TO
CIGS. GUIDANCE IN BETTER AGREEMENT ON LOWER CIGS AND SOME VSBY
RESTRICTIONS AS ANOTHER ROUND OF SHRA COMES THRU TONIGHT.
OUTLOOK...A STATIONARY FRONT IS EXPECTED TO REMAIN SOUTH AND EAST OF
THE FORECAST AREA THROUGH THE WEEKEND...KEEPING THE AREA IN A COOL
MOIST WEDGE OF HIGH PRES. RESTRICTIVE CIGS AND VSBYS WILL LIKELY
PERSIST ACRS THE REGION THRU AT LEAST SUNDAY...THEN SOME IMPROVEMENT
TO MOSTLY VFR EXPECTED EARLY NEXT WEEK...AS THE WEDGE ERODES.
CONFIDENCE TABLE...
09-15Z 15-21Z 21-03Z 03-09Z
KCLT HIGH 95% HIGH 85% HIGH 84% HIGH 90%
KGSP HIGH 94% HIGH 84% HIGH 84% HIGH 97%
KAVL HIGH 84% MED 69% HIGH 93% HIGH 83%
KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 87%
KGMU HIGH 100% HIGH 87% HIGH 84% HIGH 100%
KAND HIGH 81% HIGH 80% HIGH 90% HIGH 97%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.CLIMATE...
RECORD LOW MAX TEMPERATURES THIS WEEKEND...
AUG 16 AUG 17 AUG 18
AVL...62 1964 72 1986 70 1905
CLT...64 1964 71 1992 72 1894
GSP...64 1964 71 1971 71 1957
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...ARK
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...ARK
CLIMATE...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1041 PM CDT SAT AUG 17 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 345 PM CDT SAT AUG 17 2013
PARTLY SUNNY AND WARMER AFTERNOON CONTINUES ACROSS THE AREA. A LOT
OF THIS CLOUD COVER WILL DISSIPATE WITH THE LOSS OF DAYTIME HEATING.
HOWEVER WILL STILL SEE A DECENT AMOUNT OF MOISTURE AT THE TOP OF
TODAYS MIXED LAYER...AND AS THE LOW LEVEL JET KICKS IN
TONIGHT...COULD SEE JUST ENOUGH LIFT TO GET SOME MORE MID LEVEL
STRATUS OVER PORTIONS OF THE AREA. BEST LOW LEVEL MOISTURE CONTINUES
TO PUSH WEST...AND THINK BEST LOW STRATUS AND FOG POTENTIAL SHOULD
REMAIN WEST OF THE CWA. ALTHOUGH A SMALL CHANCE THAT SOME OF THE
LOWER STRATUS MAKES IT AS FAR EAST AS A HURON TO LAKE ANDES LINE
LATER TONIGHT INTO TOMORROW MORNING. WITH THE INCREASING LOW LEVEL
JET...WINDS WILL REMAIN A BIT BLUSTERY OVERNIGHT...WHICH SHOULD
KEEPS LOWS IN THE LOW TO MID 60S OVER THE WESTERN PORTION OF THE
CWA. ACROSS NORTHWEST IOWA AND PORTIONS OF SOUTHWEST
MINNESOTA...SEEMS LIKE WINDS COULD BECOME LIGHT ENOUGH TO ALLOW FOR
SOME PRETTY GOOD RADIATIONAL COOLING. THUS GOING WITH LOWS IN THE
LOWER TO MID 50S THERE. TOMORROW WILL SEE MORE IN THE WAY OF
SUN...ALTHOUGH AFTERNOON CU WILL AGAIN MAKE IT PARTLY CLOUDY. WARMER
AIR ALOFT CONTINUES TO MOVE IN...RESULTING IN HIGHS SEVERAL DEGREES
WARMER THAN TODAY. LOOKING AT 80S JUST ABOUT EVERYWHERE...WITH THE
WARMEST READINGS WEST OF THE JAMES RIVER. INSTABILITY INCREASES
ACROSS OUR WEST THROUGH THE DAY...BUT STRONG CAPPING WILL KEEP OUR
CWA CONVECTION FREE THROUGH 0Z. SOUTHERLY WINDS WILL AGAIN BE
BLUSTERY...WITH GUSTS IN THE 20 TO 30 MPH RANGE BY
AFTERNOON...SLIGHTLY WEAKER ACROSS NORTHWEST IOWA.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 345 PM CDT SAT AUG 17 2013
WITH THE UPPER WAVE MOVING ACROSS NRN SD ON SUNDAY AFTERNOON AND
NIGHT...DO EXPECT CONVECTION TO DEVELOP ACROSS NRN SD. A FEW OF
THESE STORMS MAY BE ABLE TO MOVE INTO THE HURON AREA AFTER
MIDNIGHT BUT GIVEN THAT THE BOUNDARY IS ACROSS NRN SD...THERE IS
NO REAL FOCUS FOR LIFT AND HAVE ONLY KEPT A SLIGHT CHANCE OF
THUNDERSTORMS. MEANWHILE...WITH THE LOW LEVEL JET SET UP ACROSS
THE AREA...EXPECT THAT THIS WILL KEEP WINDS ABOVE 5 MPH WITH SOME
ENHANCEMENT IN WINDS SPEEDS IN SW MN DOWNSTREAM OF THE BUFFALO
RIDGE IN LYON AND LINCOLN COUNTIES. ON THE OTHERHAND A WEAKER
GRADIENT WILL ALLOW WINDS AROUND 5 MPH AND BIT OF DECOUPLING IN NW
IA. LOWS WILL BE WARMEST WEST OF I29 AND AROUND MARSHALL MN IN THE
UPPER 60S...WITH LOW TO MID 60S ELSEWHERE.
A GRADUAL WARMING TREND THEN EXPECTED MONDAY AND TUESDAY WITH SOME
OF THE HOTTEST WEATHER OF THE SUMMER ACROSS THE AREA BY MID WEEK.
SOUTHERLY WINDS WILL CONTINUE TO BRING WARMER AND MORE HUMID AIR
NORTH. EVEN THOUGH DEW POINTS WILL BE IN THE MID TO UPPER 60S...OR
EVEN LOWER 70S BY TUESDAY...CUMULUS WILL BECOME LESS PREVALENT
EACH DAY AS THE INVERSION STRENGTHENS PREVENTING MOST PARCELS FROM
REACHING THEIR LCL. TEMPERATURES ALSO CONTINUE TO WARM EACH DAY
WITH 850 MB TEMPERATURES FROM THE UPPER TEENS TO LOWER 20S CELSIUS
ON MONDAY AND WITH 2 TO 5 C WARMER ON TUESDAY. THIS WILL MEAN
HIGHS FROM THE MID 80S IN PORTIONS OF SW MN AND NW IA TO THE MID
90S ALONG AND WEST OF THE JAMES RIVER. TUESDAY WILL BE 3 TO 5
DEGREES WARMER WITH 90S IN MOST LOCATIONS AND 100 IS NOT OUT OF
THE QUESTION WEST OF THE JAMES. WINDS WILL AGAIN BE STRONG ENOUGH
WITH THE LOW LEVEL JET TO KEEP TEMPERATURES AGAIN IN THE MID TO
UPPER 60S.
IN THE EXTENDED...WEDNESDAY THROUGH SATURDAY...LOOKING ABOVE
NORMAL WITH HUMID CONDITIONS LIKELY THROUGH NEXT WEEKEND. THERE IS
SOME DISAGREEMENT ABOUT HOW STRONG THE RIDGE WILL BE WITH THE
OPERATIONAL 00Z ECMWF THE STRONGEST AND THE 00Z GFS ENSEMBLE MEAN
THE WEAKEST. THE ECMWF AND CANADIAN GEM HAVE NOW BACKED OFF ON HOW
FAR SOUTH THE BACKDOOR FRONT WILL GET WITH IT BARELY REACHING I90
WHILE THE GFS IS MORE SIMILAR TO YESTERDAYS ECMWF AND HAS FRONT GO
DOWN TO I80. THE GFS SOLUTION APPEARS TO BE A RESULT OF A LOT OF
CONVECTIVE DEVELOPMENT WEDNESDAY AFTERNOON AND EVENING. GIVEN THE
DEGREE OF CAPPING...THIS APPEARS TO BE OVERDONE AND HAVE TRENDED
TOWARD THE ECMWF SOLUTION FOR THURSDAY AND FRIDAY. AS A RESULT
TEMPERATURES NEAR THE MISSOURI RIVER MAY REMAIN IN THE 90S THROUGH
THE ENTIRE WEEK. IN ADDITIONAL WITH RAIN CHANCES LOOK TO BE
CONFINED ALONG AND NORTH OF THE BOUNDARY AND HAVE REMOVED POPS IN
THE MID MISSOURI VALLEY AND PORTIONS OF NW IA. FARTHER TO THE
NORTH...MUCH MORE UNCERTAINTY ON TEMPERATURES SINCE AS ONE GOES
NORTH AS CAN BE SEEN BY THE LARGER STANDARD DEVIATIONS IN 850 MB
TEMPERATURES SHOWN BY THE GFS ENSEMBLE. THE CHANCE OF
PRECIPITATION INCREASES FARTHER NORTH AND EVEN IF IT DOES NOT RAIN
IN SW MN OR SE SD...THE SFC BOUNDARY MAY BE FORCED TO I-90 OR EVEN
FARTHER SOUTH AS RAIN COOLED OUTFLOW REINFORCES IT. SO WILL SHOW
TEMPERATURES A LITTLE COOLER THURSDAY AND FRIDAY ALONG AND NORTH
OF I90...WITH HIGHS IN THE MID TO UPPER 80S AND WARMING BACK INTO
THE 90S IN MOST PLACES BY SATURDAY. AS FOR PRECIPITATION...CANNOT
COMPLETELY RULE OUT THE CHANCE OF CONVECTION WED NIGHT THRU THU
NIGHT...ESPECIALLY ALONG HWY 14 SO WILL CONTINUE TO CARRY 20 TO 30
PERCENT POPS FOR THAT PERIOD BUT WILL GO DRY FRIDAY INTO SATURDAY.
IF THE PATTERN TRENDS MORE TOWARD THE ECMWF AND CANADIAN
GEM LATE WEEK...TEMPERATURES THURSDAY THROUGH SATURDAY COULD BE
ANOTHER 5 DEGREES WARMER.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1040 PM CDT SAT AUG 17 2013
00Z NAM12 AND LATEST RUC13 MODELS ARE CONTINUING TO SHOW THE SAME
TRENDS AS THEIR EARLIER COUNTERPARTS DID. BOTH ARE IN GOOD AGREEMENT
IN BRINGING SOME OF THE STRATUS CURRENTLY IN CENTRAL NEBRASKA
NORTHWARD TONIGHT ALONG THE LOW LEVEL JET. IN OUR FAR WEST...LOWER
END MVFR CEILINGS ARE LIKELY IN GREGORY COUNTY SOUTH DAKOTA. AT
THIS TIME...IT APPEARS THAT THE MAIN PORTION OF THIS STRATUS WILL
STAY TO THE WEST OF KHON DEEPER INTO CENTRAL SOUTH DAKOTA...BUT AM
CONCERNED THAT SOME MVFR FOG WILL DEVELOP IN THE JAMES RIVER VALLEY
AROUND SUNRISE. AS FOR CLOUDS...KEPT THE STRATUS POTENTIAL AT KHON
ONLY IN THE MVFR SCATTERED CATEGORY. FURTHER EAST...BOTH MODELS
ALSO SHOW A STRIPE OF HIGHER BASED STRATUS EXTENDING NORTHEASTWARD
FROM CENTRAL NEB TOWARD THE I 29 CORRIDOR...AS WINDS AROUND 800MB
VEER FROM THE SOUTH TO SOUTHWEST OVERNIGHT. EVIDENCE OF THIS
HAPPENING IS ALREADY OCCURRING WITH O NEILL NEB SHOWING 5000 FOOT
SCATTERED...AND SCATTERED HIGH BASED STRATUS EXTENDING SOUTH OF
THERE. THIS FAR NORTH...THE HIGHER BASED STRATUS SHOULD BE NEAR
4000 FEET AGL AND COULD VERY WELL GO BROKEN AT KFSD BEFORE
SUNRISE...POSSIBLY STAYING SCATTERED AT KSUX.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...CHENARD
LONG TERM...SCHUMACHER
AVIATION...MJ
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
637 PM CDT SAT AUG 17 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 345 PM CDT SAT AUG 17 2013
PARTLY SUNNY AND WARMER AFTERNOON CONTINUES ACROSS THE AREA. A LOT
OF THIS CLOUD COVER WILL DISSIPATE WITH THE LOSS OF DAYTIME HEATING.
HOWEVER WILL STILL SEE A DECENT AMOUNT OF MOISTURE AT THE TOP OF
TODAYS MIXED LAYER...AND AS THE LOW LEVEL JET KICKS IN
TONIGHT...COULD SEE JUST ENOUGH LIFT TO GET SOME MORE MID LEVEL
STRATUS OVER PORTIONS OF THE AREA. BEST LOW LEVEL MOISTURE CONTINUES
TO PUSH WEST...AND THINK BEST LOW STRATUS AND FOG POTENTIAL SHOULD
REMAIN WEST OF THE CWA. ALTHOUGH A SMALL CHANCE THAT SOME OF THE
LOWER STRATUS MAKES IT AS FAR EAST AS A HURON TO LAKE ANDES LINE
LATER TONIGHT INTO TOMORROW MORNING. WITH THE INCREASING LOW LEVEL
JET...WINDS WILL REMAIN A BIT BLUSTERY OVERNIGHT...WHICH SHOULD
KEEPS LOWS IN THE LOW TO MID 60S OVER THE WESTERN PORTION OF THE
CWA. ACROSS NORTHWEST IOWA AND PORTIONS OF SOUTHWEST
MINNESOTA...SEEMS LIKE WINDS COULD BECOME LIGHT ENOUGH TO ALLOW FOR
SOME PRETTY GOOD RADIATIONAL COOLING. THUS GOING WITH LOWS IN THE
LOWER TO MID 50S THERE. TOMORROW WILL SEE MORE IN THE WAY OF
SUN...ALTHOUGH AFTERNOON CU WILL AGAIN MAKE IT PARTLY CLOUDY. WARMER
AIR ALOFT CONTINUES TO MOVE IN...RESULTING IN HIGHS SEVERAL DEGREES
WARMER THAN TODAY. LOOKING AT 80S JUST ABOUT EVERYWHERE...WITH THE
WARMEST READINGS WEST OF THE JAMES RIVER. INSTABILITY INCREASES
ACROSS OUR WEST THROUGH THE DAY...BUT STRONG CAPPING WILL KEEP OUR
CWA CONVECTION FREE THROUGH 0Z. SOUTHERLY WINDS WILL AGAIN BE
BLUSTERY...WITH GUSTS IN THE 20 TO 30 MPH RANGE BY
AFTERNOON...SLIGHTLY WEAKER ACROSS NORTHWEST IOWA.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 345 PM CDT SAT AUG 17 2013
WITH THE UPPER WAVE MOVING ACROSS NRN SD ON SUNDAY AFTERNOON AND
NIGHT...DO EXPECT CONVECTION TO DEVELOP ACROSS NRN SD. A FEW OF
THESE STORMS MAY BE ABLE TO MOVE INTO THE HURON AREA AFTER
MIDNIGHT BUT GIVEN THAT THE BOUNDARY IS ACROSS NRN SD...THERE IS
NO REAL FOCUS FOR LIFT AND HAVE ONLY KEPT A SLIGHT CHANCE OF
THUNDERSTORMS. MEANWHILE...WITH THE LOW LEVEL JET SET UP ACROSS
THE AREA...EXPECT THAT THIS WILL KEEP WINDS ABOVE 5 MPH WITH SOME
ENHANCEMENT IN WINDS SPEEDS IN SW MN DOWNSTREAM OF THE BUFFALO
RIDGE IN LYON AND LINCOLN COUNTIES. ON THE OTHERHAND A WEAKER
GRADIENT WILL ALLOW WINDS AROUND 5 MPH AND BIT OF DECOUPLING IN NW
IA. LOWS WILL BE WARMEST WEST OF I29 AND AROUND MARSHALL MN IN THE
UPPER 60S...WITH LOW TO MID 60S ELSEWHERE.
A GRADUAL WARMING TREND THEN EXPECTED MONDAY AND TUESDAY WITH SOME
OF THE HOTTEST WEATHER OF THE SUMMER ACROSS THE AREA BY MID WEEK.
SOUTHERLY WINDS WILL CONTINUE TO BRING WARMER AND MORE HUMID AIR
NORTH. EVEN THOUGH DEW POINTS WILL BE IN THE MID TO UPPER 60S...OR
EVEN LOWER 70S BY TUESEDAY...CUMULUS WILL BECOME LESS PREVALENT
EACH DAY AS THE INVERSION STRENGTHENS PREVENTING MOST PARCELS FROM
REACHING THEIR LCL. TEMPERATURES ALSO CONTINUE TO WARM EACH DAY
WITH 850 MB TEMPERATURES FROM THE UPPER TEENS TO LOWER 20S CELSIUS
ON MONDAY AND WITH 2 TO 5 C WARMER ON TUESDAY. THIS WILL MEAN
HIGHS FROM THE MID 80S IN PORTIONS OF SW MN AND NW IA TO THE MID
90S ALONG AND WEST OF THE JAMES RIVER. TUESDAY WILL BE 3 TO 5
DEGREES WARMER WITH 90S IN MOST LOCATIONS AND 100 IS NOT OUT OF
THE QUESTION WEST OF THE JAMES. WINDS WILL AGAIN BE STRONG ENOUGH
WITH THE LOW LEVEL JET TO KEEP TEMPERATURES AGAIN IN THE MID TO
UPPER 60S.
IN THE EXTENDED...WEDNESDAY THROUGH SATURDAY...LOOKING ABOVE
NORMAL WITH HUMID CONDITIONS LIKELY THROUGH NEXT WEEKEND. THERE IS
SOME DISAGREEMENT ABOUT HOW STRONG THE RIDGE WILL BE WITH THE
OPERATIONAL 00Z ECMWF THE STRONGEST AND THE 00Z GFS ENSEMBLE MEAN
THE WEAKEST. THE ECMWF AND CANADIAN GEM HAVE NOW BACKED OFF ON HOW
FAR SOUTH THE BACKDOOR FRONT WILL GET WITH IT BARELY REACHING I90
WHILE THE GFS IS MORE SIMILAR TO YESTERDAYS ECMWF AND HAS FRONT GO
DOWN TO I80. THE GFS SOLUTION APPEARS TO BE A RESULT OF A LOT OF
CONVECTIVE DEVELOPMENT WEDNESDAY AFTERNOON AND EVENING. GIVEN THE
DEGREE OF CAPPING...THIS APPEARS TO BE OVERDONE AND HAVE TRENDED
TOWARD THE ECMWF SOLUTON FOR THURSDAY AND FRIDAY. AS A RESULT
TEMPERATURES NEAR THE MISSOURI RIVER MAY REMAIN IN THE 90S THROUGH
THE ENTIRE WEEK. IN ADDITIONAL WITH RAIN CHANCES LOOK TO BE
CONFINED ALONG AND NORTH OF THE BOUNDARY AND HAVE REMOVED POPS IN
THE MID MISSOURI VALLEY AND PORTIONS OF NW IA. FARTHER TO THE
NORTH...MUCH MORE UNCERTAINTY ON TEMPERATURES SINCE AS ONE GOES
NORTH AS CAN BE SEEN BY THE LARGER STANDARD DEVIATIONS IN 850 MB
TEMPERATURES SHOWN BY THE GFS ENSEMBLE. THE CHANCE OF
PRECIPITATION INCREASES FARTHER NORTH AND EVEN IF IT DOES NOT RAIN
IN SW MN OR SE SD...THE SFC BOUNDARY MAY BE FORCED TO I-90 OR EVEN
FARTHER SOUTH AS RAIN COOLED OUTFLOW REINFORCES IT. SO WILL SHOW
TEMPERATURES A LITTLE COOLER THURSDAY AND FRIDAY ALONG AND NORTH
OF I90...WITH HIGHS IN THE MID TO UPPER 80S AND WARMING BACK INTO
THE 90S IN MOST PLACES BY SATURDAY. AS FOR PRECIPITATION...CANNOT
COMPLETELY RULE OUT THE CHANCE OF CONVECTION WED NIGHT THRU THU
NIGHT...ESPECIALLY ALONG HWY 14 SO WILL CONTINUE TO CARRY 20 TO 30
PERCENT POPS FOR THAT PERIOD BUT WILL GO DRY FRIDAY INTO SATURDAY.
IF THE PATTERN TRENDS MORE TOWARD THE ECMWF AND CANADIAN
GEM LATE WEEK...TEMPERATURES THURSDAY THROUGH SATURDAY COULD BE
ANOTHER 5 DEGREES WARMER.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 630 PM CDT SAT AUG 17 2013
WILL HAVE SOME OF THE SAME AVIATION ISSUES TONIGHT AS WE DID LAST
NIGHT. BOTH THE NAM12 AND RUC13 MODELS ARE IN VERY GOOD AGREEMENT
IN BRINGING SOME OF THE STRATUS CURRENTLY IN SOUTH CENTRAL
NEBRASKA NORTHWARD TONIGHT ALONG THE LOW LEVEL JET. IN OUR FAR
WEST...UPPER END IFR TO LOWER END MVFR CEILINGS ARE LIKELY IN
GREGORY COUNTY SOUTH DAKOTA. AT THIS TIME...IT APPEARS THAT THE
MAIN PORTION OF THIS STRATUS WILL STAY TO THE WEST OF KHON DEEPER
INTO CENTRAL SOUTH DAKOTA...BUT AM CONCERNED THAT SOME MVFR FOG
WILL DEVELOP IN THE JAMES RIVER VALLEY AROUND SUNRISE. BUT FOR
CEILINGS...KEPT THE STRATUS POTENTIAL AT KHON ONLY IN THE MVFR
SCATTERED CATEGORY. FURTHER EAST...BOTH MODELS ALSO SHOW A STRIPE
OF HIGHER BASED STRATUS EXTENDING NORTHEASTWARD FROM CENTRAL NEB
TOWARD THE I 29 CORRIDOR. THIS HIGHER BASED STRATUS SHOULD BE NEAR
3500 FEET AGL AND COULD VERY WELL GO BROKEN AT KFSD BEFORE
SUNRISE.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...CHENARD
LONG TERM...SCHUMACHER
AVIATION...MJ
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
129 PM CDT FRI AUG 16 2013
.UPDATE...FOR 18Z TAFS...
&&
.AVIATION...
AN UPPER LOW IS FORECAST TO SITUATE ITSELF OVER WESTERN TN DURING THE
NEXT 24 HOURS KEEPING BKN TO OVC SKIES FOR ALL SITES THROUGH
TOMORROW. INCLUDED A TEMPO FOR LIGHT FOG IN THE EARLY MORNING
HOURS OF SATURDAY. PRECIP CHANCES INCREASE DURING THE DAY ON
SATURDAY...JUST INCLUDED VCSH AT BNA WHERE MOISTURE LOOKS BEST
AFTER 12Z.
&&
.PREV DISCUSSION... /ISSUED 932 AM CDT FRI AUG 16 2013/
UPDATE...
CLOUDS IN PLACE THIS MORNING. UPPER LEVEL TROUGH EXPECTED TO
BEGIN STRENGTHENING TODAY. 18Z PROGS SHOW CAPPING IN PLACE BUT
MOISTURE LEVELS ARE ON THE INCREASE. WEAK SFC TROUGH WILL STRETCH
FROM NRN MS THROUGH MIDDLE TN THIS AFTERNOON. THIS WILL SERVE AS
SOME WEAK FORCING WHICH MAY SPAWN SOME SHOWER ACTIVITY TODAY.
LATEST HRRR STILL IN SUPPORT OF SOME SHOWER DEVELOPMENT. HOWEVER...ANY
ACTIVITY SHOULD REMAIN ON THE LIGHT SIDE.
FOR THE FORECAST...CANNOT SEE A REASON TO CHANGE ANYTHING AT THIS
TIME. THE 18Z TEMPS PROG APPEARS TO BE IN LINE WITH THE CURRENT
FORECAST MAXES. INSTABILITY IS QUITE WEAK SO WILL CONTINUE WITH
JUST A SLIGHT CHANCE OF THUNDER.
PREV DISCUSSION... /ISSUED 641 AM CDT FRI AUG 16 2013/
UPDATE...FOR 12Z AVIATION FORECASTS.
AVIATION...EXPECT VFR CIGS THROUGHOUT THE TAF PERIOD. DESPITE
CIGS...HOWEVER...SOME VIS RESTRICTIONS ARE LIKELY OVERNIGHT AT
CKV/CSV DUE TO PATCHY FOG. SCATTERED -SHRA/-TSRA ARE EXPECTED TO
OCCUR, ESPECIALLY IN THE AFTERNOON AND EVENING. HOWEVER, WOULD BE
HARD PRESSED TO DETERMINE IF OR WHEN A -SHRA/-TSRA MIGHT AFFECT
ANY PARTICULAR TERMINAL. THUS, WILL LEAVE MENTION OF PRECIP OUT OF
TAFS FOR NOW. LIGHT EAST-T0-NORTHEAST WINDS ARE ANTICIPATED
THROUGHOUT THE TAF PERIOD.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
11
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
932 AM CDT FRI AUG 16 2013
.UPDATE...
CLOUDS IN PLACE THIS MORNING. UPPER LEVEL TROUGH EXPECTED TO
BEGIN STRENGTHENING TODAY. 18Z PROGS SHOW CAPPING IN PLACE BUT
MOISTURE LEVELS ARE ON THE INCREASE. WEAK SFC TROUGH WILL STRETCH
FROM NRN MS THROUGH MIDDLE TN THIS AFTERNOON. THIS WILL SERVE AS
SOME WEAK FORCING WHICH MAY SPAWN SOME SHOWER ACTIVITY TODAY.
LATEST HRRR STILL IN SUPPORT OF SOME SHOWER DEVELOPMENT. HOWEVER...ANY
ACTIVITY SHOULD REMAIN ON THE LIGHT SIDE.
FOR THE FORECAST...CANNOT SEE A REASON TO CHANGE ANYTHING AT THIS
TIME. THE 18Z TEMPS PROG APPEARS TO BE IN LINE WITH THE CURRENT
FORECAST MAXES. INSTABILITY IS QUITE WEAK SO WILL CONTINUE WITH
JUST A SLIGHT CHANCE OF THUNDER.
&&
.PREV DISCUSSION... /ISSUED 641 AM CDT FRI AUG 16 2013/
UPDATE...FOR 12Z AVIATION FORECASTS.
AVIATION...EXPECT VFR CIGS THROUGHOUT THE TAF PERIOD. DESPITE
CIGS...HOWEVER...SOME VIS RESTRICTIONS ARE LIKELY OVERNIGHT AT
CKV/CSV DUE TO PATCHY FOG. SCATTERED -SHRA/-TSRA ARE EXPECTED TO
OCCUR, ESPECIALLY IN THE AFTERNOON AND EVENING. HOWEVER, WOULD BE
HARD PRESSED TO DETERMINE IF OR WHEN A -SHRA/-TSRA MIGHT AFFECT
ANY PARTICULAR TERMINAL. THUS, WILL LEAVE MENTION OF PRECIP OUT OF
TAFS FOR NOW. LIGHT EAST-T0-NORTHEAST WINDS ARE ANTICIPATED
THROUGHOUT THE TAF PERIOD.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
21
AREA FORECAST DISCUSSION...UPDATED
NWS MORRISTOWN TN
1010 AM EDT FRI AUG 16 2013
.DISCUSSION...
ANALYSIS OF RAOBS ACROSS THE REGION AND SATELLITE IMAGERY SHOW A
DEFORMATION ZONE AT 850 MB ACROSS THE SOUTHERN APPALACHIANS. MOST
PRECIP IS STAYING SOUTH OF THE AXIS OF DEFORMATION ACROSS GA/SC. A
FEW SHOWERS ARE SPREADING INTO THE SOUTHERN TN VALLEY AND SW
NC...BUT ARE MAKING SLOW NORTHWARD PROGRESS. WITH THE UPPER LOW
STAYING STATIONARY OVER AL TODAY...WE SHOULD NOT SEE MUCH CHANGE TO
THIS PATTERN. POPS WILL BE LOWERED ACROSS THE BOARD. THE EXTENSIVE
CLOUD COVER WE ARE SEEING THIS MORNING APPEARS WELL ENTRENCHED
BASED ON AREA 12Z SOUNDINGS AND RUC FORECAST SOUNDINGS...SO TEMPS
WILL BE LOWERED AS WELL...ESPECIALLY IN SOUTHERN AREAS.
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
DGS
AREA FORECAST DISCUSSION...CORRECTION
NWS SAN ANGELO TX
336 PM CDT FRI AUG 16 2013
.SHORT TERM...
/Tonight and Tomorrow/
Visible satellite imagery shows sunny skies across West Central
Texas this afternoon. The latest mesoanalysis indicates a stable
environment over our area, with an instability axis across South and
far West Texas.
The models, including the 3KM HRRR model develop scattered
thunderstorms over Eastern New Mexico and far West Texas in the
instability axis during the late afternoon and evening. Upper level
northerly flow will keep this activity west of our area for tonight.
Lows will be in the mid 60s to lower 70s.
Going with a dry forecast for Saturday across the area. Isolated
thunderstorms will probably fire to our west during the afternoon
hours. The upper level northerly flow should keep the storms west of
our area. Highs will be in the lower to mid 90s.
.LONG TERM...
/Saturday Night through Friday/
The upper level flow will be north to northeast next week as a high
pressure ridge sets up from the Southern Rockies into the Central
Plains. Basically a normal summertime pattern with little upper
level and mesoscale forcing. Temperatures will be near or slightly
above seasonable normals. Highs will be in the 90s with lows in the
upper 60s to lower 70s. Going with a dry forecast through the
extended period.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 66 92 67 94 68 / 10 10 5 5 5
San Angelo 67 93 68 95 68 / 10 10 5 5 5
Junction 68 94 69 97 66 / 10 10 5 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
21
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
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.
&&
$$
21
AREA FORECAST DISCUSSION
NWS MIDLAND/ODESSA TX
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.
&&
.PRELIMINARY POINT TEMPS/POPS...
ANDREWS TX 69 94 70 95 / 10 10 10 0
BIG SPRING TX 72 95 70 96 / 10 10 10 0
CARLSBAD NM 70 98 71 99 / 30 10 20 10
DRYDEN TX 74 104 74 103 / 10 20 10 0
FORT STOCKTON TX 73 97 71 96 / 20 20 10 10
GUADALUPE PASS TX 66 94 68 92 / 20 20 20 20
HOBBS NM 67 94 67 93 / 30 10 20 0
MARFA TX 59 90 60 88 / 20 40 10 20
MIDLAND INTL AIRPORT TX 71 96 69 96 / 10 10 10 10
ODESSA TX 71 96 70 96 / 10 10 10 10
WINK TX 72 99 72 99 / 20 10 10 10
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...NONE.
TX...NONE.
&&
$$
10/67
AREA FORECAST DISCUSSION
NWS AMARILLO TX
1149 PM CDT THU AUG 15 2013
.AVIATION...DISCUSSION FOR 06Z TAFS
VFR CONDITIONS SHOULD PREVAIL WITH THE ONE CAVEAT BEING THE POTENTIAL
FOR SOME BR OR MAYBE A FEW LOW CLOUDS AT THE TAF SITES BTW 10-15Z
FRI MORNING. CONFIDENCE IS STILL TOO LOW TO INCLUDE ANY RESTRICTIONS
AS PREVAILING OR TEMPO...BUT AMENDMENTS COULD BE NEEDED. THERE COULD
BE A STRAY THUNDERSTORM FRI AFTERNOON/EVENING...BUT AGAIN CONFIDENCE
IS TOO LOW FOR ANY MENTION IN THE TAFS. WINDS WILL BE LIGHT AND
SOMEWHAT VARIABLE...BUT GENERALLY CONTAINING A SRLY OR ERLY
COMPONENT.
TAFS WILL BE OUT AT 0520Z.
SIMPSON
&&
.PREV DISCUSSION... /ISSUED 945 PM CDT THU AUG 15 2013/
UPDATE...
SEVERE THREAT CONTINUES TO DIMINISH AS IT APPEARS THAT MOST OF THE
CONVECTIVE ACTIVITY WILL REMAIN EAST OF THE PANHANDLES. LOW LEVEL
JET...AND ASSOCIATED INCREASE IN CONVECTIVE ACTIVITY HAS YET TO
MATERIALIZE...THUS HAVE CANCELED THE REMAINDER OF THE WATCH. HAVE
ALSO DECREASED POPS ACROSS THE PANHANDLES TO 20 TO 30 PERCENT.
JOHNSON
PREV DISCUSSION... /ISSUED 814 PM CDT THU AUG 15 2013/
UPDATE...
WINDOW OF RISK OF SEVERE WEATHER IS DIMINISHING...EXCEPT IN THE
EASTERN OK AND NE TX PANHANDLE WHICH MAY YET SEE STORMS DEVELOP IN
RESPONSE TO A DEVELOPING WEAK LOW LEVEL JET. THUS...WILL KEEP THE
WATCH GOING IN BEAVER...LIPSCOMB...OCHILTREE...AND HEMPHILL
COUNTIES...BUT HAVE CANCELED THE WATCH FOR THE REMAINDER OF THE TX
PANHANDLE.
JOHNSON
PREV DISCUSSION... /ISSUED 710 PM CDT THU AUG 15 2013/
AVIATION...DISCUSSION FOR 00Z TAFS
MAINLY VFR TAFS SHOULD PREVAIL THOUGH THERE ARE A FEW POTENTIALLY
AMENDABLE FEATURES OF NOTE. FIRST...SCT SHOWERS AND STORMS COULD
AFFECT ANY OF THE 3 TAF SITES THIS EVENING INTO POSSIBLY THE FIRST
FEW HOURS OF FRIDAY MORNING. HOWEVER...CONFIDENCE IS NOT HIGH ENOUGH
TO INCLUDE ANY MENTION AT THIS TIME. SECOND...A FEW LOW CLOUDS AND/OR
REDUCED VISIBILITIES WILL BE POSSIBLE AT ANY OF THE SITES FROM
16/10Z-16/15Z. WINDS WILL GENERALLY BE LIGHT THROUGH THE PERIOD
OUTSIDE OF ANY THUNDERSTORMS.
SIMPSON
PREV DISCUSSION... /ISSUED 326 PM CDT THU AUG 15 2013/
DISCUSSION...
LITTLE OR NO CHANGES TO THE PREVIOUS GRIDS AND FORECAST AS THE
WEATHER PATTERN DOES NOT CHANGE MUCH. UPPER HIGH OVER THE FOUR
CORNERS AND SOUTHWESTERN STATES THROUGH THE WEEKEND WILL MAINTAIN A
NORTHWESTERLY UPPER FLOW TONIGHT...TRANSITIONING TO NORTHERLY BY
FRIDAY NIGHT AND SATURDAY. LOOKING AT THE TTU-WRF...NAM...GFS...AND
ECMWF...BETTER ORGANIZED CONVECTION COULD POSSIBLY HOLD OFF UNTIL
AROUND 00Z FRIDAY OR LATER. THE LATEST HRRR DEVELOPS CONVECTION
ACROSS THE NORTHWEST SECTIONS OF THE FORECAST AREA BY 20Z TODAY WHICH
THEN MOVES SOUTHEAST ACROSS THE WESTERN AND CENTRAL TEXAS PANHANDLE
AROUND 22Z TODAY TO AROUND 00Z TO 02Z FRIDAY. SINCE NOT MUCH
DEVELOPING AS OF 20Z TODAY ACROSS THE PANHANDLES...THINKING THAT THE
HRRR MAY BE THE ODD MODEL OUT. CONVECTION CURRENTLY OVER OKLAHOMA AND
EAST CENTRAL NEW MEXICO MOVING SOUTH AND SOUTHEAST. WILL CONTINUE TO
MONITOR TRENDS...BUT WITH CAPES FORECAST TO BE IN THE 1500 TO 2500
J/KG RANGE AND SURFACE DEW POINTS IN THE 60S...CANNOT RULE OUT
CONVECTION DEVELOPING PRIOR TO 00Z FRIDAY.
AS THE UPPER HIGH BROADENS OVER THE SOUTHWESTERN STATES OVER THE
WEEKEND...THE UPPER FLOW TRANSITIONS TO NORTHERLY AND EVEN
NORTHEASTERLY BRINGING A GRADUAL END TO THE CONVECTION BY SUNDAY.
WARMER AND DRIER CONDITIONS SUNDAY THROUGH NEXT WEDNESDAY WITH HIGHS
CLIMBING BACK UP INTO THE 90S.
SCHNEIDER
FIRE WEATHER...
AN UPPER RIDGE ACROSS THE FOUR CORNERS REGION AND THE SOUTHWESTERN
STATES WILL MAINTAIN A NORTHWESTERLY TO NORTHERLY UPPER FLOW ACROSS
THE PANHANDLES THROUGH THE WEEKEND. SHOWERS AND THUNDERSTORMS WILL
DEVELOP ACROSS SOUTHEASTERN AND EASTERN COLORADO AND WESTERN AND
SOUTHWESTERN KANSAS LATER TODAY AND TONIGHT AND WILL MOVE SOUTHEAST
ACROSS THE PANHANDLES. NO ELEVATED OR CRITICAL FIRE WEATHER
CONDITIONS ARE EXPECTED THROUGH THE MIDDLE OF NEXT WEEK AS MINIMUM
AFTERNOON RELATIVE HUMIDITIES REMAIN AT OR ABOVE 20 PERCENT THROUGH
THE MIDDLE OF NEXT WEEK.
SCHNEIDER
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
09/16
AREA FORECAST DISCUSSION
NWS SPOKANE WA
236 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...
Tonight: The Pacific Northwest will transition to a more
progressive flow pattern tonight into the weekend. An impressive
looking low pressure system over the Aleutians this afternoon will
direct a stronger upper level jet into the region over the next
couple of days. The increase in mid and upper level flow will aid
in the organization of thunderstorms over central Oregon this
afternoon and evening. We will be keeping a close eye on how
storms in Oregon evolve this evening, and their potential to
migrate into southeast Washington. At this time, RUC analysis of
instability suggests that storms will have a tough time surviving
once they move off the high terrain of central and northeast
Oregon. The last several runs of the NAM show thunderstorms
reaching as far east as Garfield and Asotin counties this evening.
Then overnight, the model regenerates elevated showers and
thunderstorms along the 700-500mb baroclinic axis from northeast
Oregon across the Camas Prairie to southern Shoshone county.
Precipitation amounts from any late night convection should be
pretty light. Model soundings suggest marginal elevated
instability and rapid cell motion.
Saturday and Saturday Night: On shore flow will strengthen
tomorrow as a shallow open-wave trough moves inland. The models are
in good agreement that there will be enough lingering low and mid
level moisture over northeast Oregon and the southern Idaho
Panhandle to retain a slight chance of showers and thunderstorms
over the Blues, Camas Prairie and Shoshone county. There may also
be enough cooling aloft with the upper trough axis to generate
isolated afternoon showers and thunderstorms over the mountains
near Northport, Priest Lake and Bonners Ferry.
Otherwise, Saturday afternoon/evening will be one of the breezier
days we have had in a while which isn`t saying much. Our recent
weather pattern hasn`t produced much widespread breeziness
lately. The Palouse, West Plains and Upper Columbia Basin will
likely experience sustained winds up to 15 mph with gusts to
around 20 mph in the afternoon. /GKoch
Sunday through Wednesday evening: A fairly benign weather pattern
through mid week. The Inland Northwest will be under a relatively
dry westerly flow pattern. The jet stream will remain well north
of the region into BC, which will place the Inland Northwest on
the more stable side of the jet. Shortwave disturbances will
generally bring some showers north of the region into BC through
the period and may give us a little bit of wind as they do so.
Temperatures will by near average with highs in the 80s for most
valley locations. /SVH
Thursday and Friday: A Low from Northern California is expected to
pass through the SE portion of Washington and the Central ID
Panhandle during this period. The models are not agreeing on the
timing of the Low passing. The GFS and GEM are putting the passing
on Friday morning while the ECMWF is nearly 24 hours behind. A few
more model runs will hopefully resolve this issue. The models are
carrying more moisture with this Low. With that in mind, the
chances of receiving a wetting rain and possible isolated
thunderstorm in the vicinity of the Low is increased for the Blue
Mountains and Camas Prairie area. Temperatures are expected to
remain around the normals for the month of August. /JDC
&&
.AVIATION...
18Z TAFS: A mainly dry frontal passage is expected today and
tonight over the Inland Northwest. Some sprinkles will accompany
the front this morning around Moses Lake. Isolated thunderstorms
will be possible over the Cascades between 21z-01z. Clusters of
stronger thunderstorms are expected over central and northeast
Oregon this afternoon/evening. These storms may migrate (as
they weaken) toward Lewiston this evening. Additional high based
showers will be possible in the 08z-13z time frame over far
southeast Washington into the southern Idaho Panhandle. No ceiling
or visibility obstructions are anticipated with evening or
overnight showers/t-storms. /GKoch
&&
.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 / 10 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 / 0 0 0 0 0 0
Wenatchee 66 87 64 88 64 88 / 0 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
1032 PM CDT SAT AUG 17 2013
UPDATED AVIATION PORTION FOR 06Z 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 06Z TAF ISSUANCE
ISSUED AT 1031 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 EVENTUALLY 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...SO FG THERE WL BE MORE PATCHY THAN LAST NGT.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......SKOWRONSKI
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST 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 18Z TAF ISSUANCE
ISSUED AT 1207 PM CDT FRI AUG 16 2013
VFR CONDITIONS WILL PROVIDE GOOD FLYING WEATHER OVER THE
TAF PERIOD. SCATTERED CUMULUS CLOUDS WITH CIGS IN THE 5-7 KFT RANGE
TO BUILD MIDDAY BEFORE DISSIPATING EARLY THIS EVENING. BETWEEN
08-12Z SATURDAY MORNING...PATCHY GROUND FOG WILL IMPACT AREA
AIRPORTS. FOG WILL BE THE MOST WIDESPREAD AND DENSE OVER
NORTH-CENTRAL WISCONSIN.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......RDM
AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
612 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 00Z TAFS THROUGH 00Z SUNDAY AFTERNOON)
ISSUED AT 609 PM MDT SAT AUG 17 2013
VFR ACROSS THE AREA THROUGH THIS EVENING. A FEW LIGHT SHOWERS
POSSIBLE THROUGH EARLY EVENING BUT OTHERWISE ONLY HIGH CLOUDS
EXPECTED OVER SOUTHEAST WYOMING. FOG MAY AGAIN DEVELOP OVER THE
NEBRASKA PANHANDLE LATE TONIGHT AND LAST THROUGH MID SUNDAY
MORNING BEFORE COMPLETELY DISSIPATING. LIFR CONDITIONS POSSIBLE
WITH THE FOG. ISOLATED THUNDERSTORMS EXPECTED SUNDAY AFTERNOON
WITH ERRATIC GUSTY WINDS NEAR THUNDERSTORM ACTIVITY.
&&
.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...LIEBL
FIRE WEATHER...RJM
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
357 AM MDT SUN AUG 18 2013
.SHORT TERM...ONCE AGAIN SOME STRATUS AND FOG WERE DEVELOPING OVER
THE NERN PLAINS EARLY THIS MORNING. A WELL DEFINED DENVER CYCLONE
WAS OVER SWRN WELD COUNTY AND WILL LIKELY PULL SOME OF THIS
STRATUS BACK WESTWARD ACROSS MUCH OF WELD COUNTY BY 12Z. APPEARS
THE LOW CLOUDS WILL LINGER THRU THE LATE MORNING HOURS ACROSS THE
NERN PLAINS BEFORE BREAKING UP BY 18Z.
FOR THIS AFTN AN UPPER LEVEL RIDGE WILL BE OVER THE AREA WITH WEAK
MID LVL FLOW. THERE WILL BE AN INCREASE IN SUBTROPICAL MOISTURE
WITH PRECIPITABLE WATER SLOWLY RISING. OVERALL INSTABILITY IS NOT
THAT UNSTABLE ACROSS THE HIGHER TERRAIN AND FRONT RANGE WHERE CAPES
WILL BE BLO 500 J/KG. OVER THE NERN PLAINS CAPES WILL BE BETTER
WITH VALUES RANGING FM 1500-2000 J/KG. WILL SEE SOME HIGH BASED
SHOWER AND TSTM ACTIVITY OVER THE HIGHER TERRAIN WITH OUTFLOW
BOUNDARIES TRIGGERING STRONGER STORMS OVER THE PLAINS WHERE
INSTABILITY WILL BE BETTER. AS FOR HIGHS 850-700 MB TEMPS WOULD
SUPPORT READINGS IN THE LOW TO MID 90S OVER NERN CO WITH A FEW UPPER
90S POSSIBLE ALONG THE FRONT RANGE.
BY TONIGHT TSTM ACTIVITY SHOULD GRADUALLY END IN THE EARLY EVENING
HOURS. MAY SEE SOME REDEVELOP OF STRATUS AND FOG OVER THE NERN
PLAINS AFTER MIDNIGHT.
.LONG TERM...MODELS SHOW LITTLE MOVEMENT IN THE STRONG UPPER
LEVEL RIDGE CENTERED JUST EAST OF THE CONTINENTAL DIVIDE ON
MONDAY DURING THE UPCOMING WEEK. ALTHOUGH 500MB HEIGHTS ARE
PROGGED TO GRADUALLY LOWER LATER IN THE WEEK AS THE SWIFT ZONAL
FLOW UP ALONG THE U.S./CANADIAN BORDER DIPS SOUTH AS THE CUTOFF
LOW NOW OFF THE CALIFORNIA COAST FILLS AND EJECTS NEWRD OVER THE
NRN ROCKIES BY FRIDAY. THIS WOULD CAUSE TEMPERATURES LOCALLY TO
MODERATE SOME...GOING FROM ABOVE AVERAGE ON MONDAY-WEDNESDAY TO
BELOW AVERAGE BY THE WEEKEND. A PERSISTENT ALBEIT LIGHT
SOUTHWESTERLY 700-500MB FLOW WILL CONTINUE TO ADVECT MINOR WAVES
OF MOIST UNSTABLE SUBTROPICAL AIR UP OVER WESTERN COLORADO
BENEATH THE UPPER RIDGE DURING THE UPCOMING WEEK. THIS WILL RESULT
IN DAILY ROUNDS OF ISOLATED TO SCATTERED T-STORMS PRIMARILY ALONG
AND WEST OF THE CONTINENTAL DIVIDE. LIGHT STEERING WINDS AND
GRADUALLY HIGHER PRECIPITABLE WATER VALUES MAY RESULT IN LOCALLY
HEAVY RAINFALL FROM THESE SLOW MOVING STORM CELLS. EAST OF THE
MOUNTAINS...ATMOSPHERE APPEARS QUITE DRY AND CAPPED FOR MUCH OF
THE WEEK RESULTING IN LITTLE IF ANY T-STORM DEVELOPMENT. HOWEVER
ON WEDNESDAY...MODELS DO SHOW AN INCREASE IN DEWPOINTS AND PW
VALUES ON THE PLAINS WITH THE PASSAGE OF A WEAK 700-500MB
SHORTWAVE TROUGH. AT PRESENT TIME...DO NOT HAVE ANY T-STORMS IN
THE FCST FOR WEDNESDAY EAST OF THE MTNS WITH QUITE ABIT OF CIN
AROUND. HOWEVER SHOULD THE MODELS CONTINUE TO INDICATE THIS
INCREASE IN LOW/MID-LEVEL MOISTURE WITH EACH RUN...WILL PROBABLY
NEED TO ADD AT LEAST A SLIGHT CHANCE OF AFTERNOON/EVENING STORMS
FOR THE PLAINS WEDNESDAY AFTERNOON AND EVENING.
&&
.AVIATION...DENVER CYCLONE WAS OVER SWRN WELD COUNTY AND IS FCST
TO STAY OVER SRN WELD THIS MORNING. LATEST HRRR KEEPS THE STRATUS
AND FOG TO THE NORTH AND NE OF DIA AS SFC WINDS STAY WSW SO WILL
KEEP OUT OF THE TAF. BY EARLY AFTN WINDS WILL BECOME LIGHT ENE
HOWEVER OUTFLOW BOUNDAIRES FM HIGH BASED CONVECTION OVER THE
FOOTIHLLS MAY TRACK ACROSS IN THE 21Z-23Z TIMEFRAME WITH WINDS
SHIFTING TO THE NW WITH SPEEDS IN THE 10-20 MPH RANGE. AT THIS
TIME LOOKS LIKE TSTMS WILL STAY MOSTLY TO EAST SO WILL ONLY
MENTION VCTS. BY THIS EARLY THIS EVENING WINDS WILL BECOME WSW AND
THEN SSW BY 06Z.
&&
.HYDROLOGY...WIDELY SCATTERED THUNDERSTORMS WILL DEVELOP THIS
AFTERNOON HOWEVER RAINFALL AMOUNTS SHOULD BE UNDER ONE QUARTER
INCH IF THEY MOVE OVER THE BURN AREAS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....BAKER
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
558 AM EDT Sun Aug 18 2013
...UPDATED FOR HIGH RISK OF RIP CURRENTS AND RAIN TOTALS...
...UPDATED FOR ISSUANCE OF FLASH FLOOD WATCH FOR FLORIDA PANHANDE...
.UPDATE...
Overall, models have a poor handle on this current scenario.
Unfortunately, our 18/06z hi-res ARW mentioned earlier in the near
term section did not run due to technical difficulties. The decision
has been made to issue a flash flood watch for today for the Florida
zones west of the Apalachicola River. The watch was primarily based
on the following factors.
1) Radar shows moderate rain already entering Walton county, and
this area experience flooding yesterday. There is some extremely
heavy rain offshore of Walton county by about 65 miles gradually
inching eastward. The ground is saturated and flash flood guidance
is likely too high in some of the watch area, especially Walton
County.
2) There appears to be a warm frontal boundary situated just inland
from the coast. This could serve as a focus for convection later
this afternoon across already saturated areas.
3) Several of the recent HRRR runs show a scenario similar to 2)
happening, although they differ on the locations. In fact, some of
the runs show areas farther to the east around Tallahassee getting
some hefty totals today, but confidence is not yet high enough to
expand the watch beyond what is being issued, although trends will
have to be monitored closely.
Overall, this is a low confidence forecast. It would not be
surprising to see either the watch expanded later today, or perhaps
canceled early.
&&
.NEAR TERM [Through Today]...
The main concern for today is the potential for additional flooding.
We are watching with interest a fairly well defined MCS moving
northeastward south of Mobile this morning. Some of the models may
be having some trouble with this feature as the NAM appears to be on
the weak side and our local 18/00z ARW run does not see this feature
very well (uses 00z NAM boundary conditions). The 18/00z GFS does
see this feature, but based on recent satellite/radar trends, it may
be just a tad too far west with its axis of heaviest precip
associated with it. This raises some concern about the potential for
additional flash flooding over the western portions of the forecast
area today due to low flash flood guidance values if this feature
moves just slightly more to the east. There is also ongoing areal
flooding in Walton county, so flash flood guidance values are
probably overdone in that county by quite a bit.
The plan of action right now is to observe the trends in the MCS on
satellite/radar over the next few hours and wait for some additional
pieces of hi-res guidance to come in before making a decision about
whether or not to re-issue the flash flood watch over the western
areas. From a model perspective, the trends in the HRRR as well as
our local 18/06z ARW run will be important as our 06z ARW uses the
00z GFS for boundary conditions and may have a better handle on this
feature than our 00z run.
Persistent moderate onshore flow with higher gusts continues to
generate a high risk for rip currents for Walton...Bay and to a
lesser extent Gulf counties thru this eve.
&&
.SHORT TERM [Tonight through Tuesday]...
The large scale pattern continues to shift tonight. This is
highlighted by ridging over west half of Conus, Ern trough lifting
Newd with low opening up into OH Valley, and deep layer Atlc ridge
building WSW in its place into SE states. At surface, building
ridge aids in weakening quasi-stnry front and nudging it Nwd ending
its local focus for showers and thunderstorms. Low level flow also
begins to back to ESE. With low over Wrn Gulf, and trough axis
still to our west, and tropical moisture plume barely out of our
area, a good chance of post sundown convection across Wrn waters
and adjacent coast, Also, reinvigorated east coast sea breeze may
cross I-75 keep convection in Ern counties past sunset.
During the rest of the period, Ern trough lifts further Newd and
flattens out. This allows Wrn and Atlc ridges to advance Ewd and Wwd
respectively bridging by end of period cutting off tropical plume
and progressively diminishing depth of moisture column depth but
ridge not strong enough to suppress convection. This shifts
steering flow to deepening ELY. By Tues, front has largely
dissipated with surface high anchored over NE SC/NW GA thus we
transition to a more typical summertime pattern with Gulf and Atlc
seabreeze/ mesoscale boundary generated aftn and eve convection.
With PWATS remaining above 2 inches thru the period, expect a good
chance of convection each day and any seabreeze/ boundary clashes
could ignite strong to isold severe storms.
Will go with 30-50% NE-SW POP gradient tonight, 30-60% SE-NW on
Mon and 30-50% SE-NW on Tues. Min temps in low 70s tonight. Highs
Mon and Tues return to near climo with upper 80s NW to low 90s SE
with Max hear indices around 100 degrees.
&&
.LONG TERM [Tuesday Night 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.
&&
.MARINE...
Local waters remain between ridge to our NE and weak area of low
pressure to our SW. this will keep winds and especially seas
elevated today. Introduced exercise caution for seas Wrn waters
thru this eve. Thereafter, expect light to moderate southeast
then east winds along with decreasing seas thru at least Thursday.
&&
.AVIATION...
[Through 06z Monday] MVFR to IFR conditions are expected to develop
during the early morning hours this morning. Another round of
convection is expected across the area later today, most likely at
KDHN and KECP.
&&
.FIRE WEATHER...
There are currently no fire weather concerns with moist conditions
in place.
&&
HYDROLOGY...
During the last 24hrs (thru 5am EDT)...ample rain fell with the
focus across the Florida Panhandle. This is reflected in the
following MESONET sites (in inches)
Southport 5.10 Panama City 4.45 and 3.56
Destin 3.84 Pan Cty Beach 3.06
Marianna 3.40 Chipley 4.06
Several local river systems have had (or will soon have) 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. The next few river model runs
should be able to focus on the main threat areas, since these models
will have a more complete picture of the area rainfall the past few
days. 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 89 73 91 73 91 / 60 30 50 30 40
Panama City 87 76 88 76 87 / 70 40 50 30 50
Dothan 86 72 89 72 90 / 70 40 60 30 50
Albany 87 72 90 72 91 / 70 30 60 40 50
Valdosta 89 72 91 72 92 / 60 30 50 40 40
Cross City 90 72 91 72 92 / 60 30 40 40 30
Apalachicola 86 77 86 77 86 / 60 40 50 30 40
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...HIGH RIP CURRENT RISK thru this Eve Walton...Bay and Gulf.
FLASH FLOOD WATCH Panhandle.
GA...None.
AL...None.
GM...None.
&&
$$
AVIATION/FIRE WX/NEAR TERM...DVD
HYDROLOGY...Block
Long Term...Lamers/Moore
Short Term/Marine...Block
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
455 AM EDT SUN AUG 18 2013
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS STILL SHOW AN AMPLIFIED UPPER
LEVEL PATTERN ACROSS THE EASTERN CONUS HIGHLIGHTED BY DEEP TROUGHING
ALONG AND JUST TO THE EAST OF THE MS RIVER VALLEY. SYNOPTIC
INFLUENCE FROM THIS FEATURE WILL RESULT IN THE POTENTIAL FOR SOME
VERY HEAVY RAINFALL ALONG THE NORTH-CENTRAL GULF COAST OVER THE NEXT
24 HOURS. HOWEVER...THIS ORGANIZED RAINFALL BANDING WILL BE HELD TO
OUR NORTHWEST BY A PROTECTIVE UPPER RIDGE THAT IS NOW IN PLACE OVER
THE FL PENINSULA. CLOSER TO THE SURFACE...THE RIDGE AXIS IS LOCATED
WELL TO OUR NORTH PROVIDING THE REGION WITH AN EAST TO SOUTHEAST
GRADIENT FLOW THAT WILL BE WITH US THROUGH THE EARLY PORTION OF THE
WEEK.
REGIONAL RADARS HAVE QUIETED DOWN CONSIDERABLY DURING THE PAST
SEVERAL HOURS WITH JUST A FEW TYPICAL NOCTURNAL MARINE SHOWERS WELL
OFFSHORE. THE RADAR SHOULD REMAIN ON THE QUIET SIDE THROUGH THE
MORNING HOURS OVER THE LAND MASS...HOWEVER THE INGREDIENTS ARE THERE
FOR ANOTHER ACTIVE THUNDERSTORM PATTERN ALONG THE FL WEST COAST
LATER THIS AFTERNOON AND EVENING. MORE ON THIS POTENTIAL IN THE
SHORT TERM DISCUSSION BELOW.
&&
.SHORT TERM (TODAY THROUGH TUESDAY)...
TODAY/TONIGHT...THE FINAL DAY OF THE WEEKEND WILL FEATURE GENERALLY
QUIET CONDITIONS FOR THE MORNING HOURS AS TEMPERATURES CLIMB TOWARD
THE LOWER 90S THROUGH A MIX OF SUN AND CLOUDS. THE LOW LEVEL
SYNOPTIC PATTERN WILL FEATURE EASTERLY FLOW THAT HAS BEEN A
RECURRING THEME THIS SUMMER AND IS THE FAVORED FLOW FOR AN ACTIVE
THUNDERSTORM PATTERN ALONG THE I-75 CORRIDOR DURING THE LATE
AFTERNOON AND EVENING HOURS. THERE MAY BE JUST ENOUGH BOUNDARY LAYER
FLOW TO KEEP ANY FEEBLE WEST COAST SEA-BREEZE FROM MOVING
INLAND...HOWEVER AT THE VERY LEAST WE WILL SEE A PARTIAL COLLAPSE OF
THE WIND FIELDS THIS AFTERNOON OVER THE NEARSHORE WATERS. THIS LACK
OF WIND WILL SET UP A SPEED CONVERGENCE ZONE NEAR THE COAST AND
SHOULD BE ENOUGH TO FORCE SCT-NMRS SHOWERS AND STORMS AFTER 3-4PM.
STORMS SHOULD GET GOING FIRST (EARLY TO MID AFTERNOON) OVER THE
SOUTHERN AND SOUTH-CENTRAL INTERIOR ZONES IN A SCT NATURE AND THEN
PROGRESS WEST AND NORTHWEST TOWARD THE TAMPA BAY AREA LATE IN THE
DAY (LATE AFTERNOON AND EARLY EVENING). IT WILL BE DURING THIS LATE
DAY / EVENING TIME FRAME THAT THE STORMS SHOULD BECOME MORE NMRS IN
NATURE. HAVE GONE WITH LIKELY 60% POPS ALONG THE ENTIRE I-75
CORRIDOR...HOWEVER...BASED ON THE LATEST HI-RESOLUTION CONVECTION
ALLOWING GUIDANCE SUITE...EVEN THIS COVERAGE MAY BE ON THE
CONSERVATIVE SIDE. GUIDANCE ALSO IS IN GOOD AGREEMENT THAT THE
ACTIVITY WILL LINGER WELL INTO THE EVENING...ESPECIALLY FOR THE
COASTAL ZONES. THIS IS AGAIN FAIRLY TYPICAL FOR THIS SYNOPTIC SETUP.
FINALLY AFTER 11 PM OR SO...WE SHOULD SEE THE LAST OF THE STORMS
DISSIPATE OR MOVE OFFSHORE...LEAVING THE LAND ZONES WITH A GENERALLY
DRY FORECAST FOR THE SECOND HALF OF THE NIGHT.
BOTTOM LINE...ANYONE WITH OUTDOOR OR TRAVEL PLANS ALONG THE I-75
CORRIDOR OR WITH NEAR SHORE BOATING PLANS FOR THE LATE DAY / EVENING
HOURS SHOULD BE PREPARED FOR RAPIDLY DEVELOPING CLUSTERS OF
STORMS.
MONDAY/TUESDAY...
OVERALL SYNOPTIC PATTERN CHANGES LITTLE FOR THE FIRST TWO DAYS OF
THE WORK WEEK. THE RIDGE ALOFT HOLDS POSITION...BUT NOT STRONG
ENOUGH TO SIGNIFICANTLY SUPPRESS CONVECTION...AND THE SURFACE RIDGE
POSITION KEEPS OUR FLOW FROM THE EAST. THE ONLY CHANGE IS A SLIGHT
DECREASE IN COLUMN MOISTURE INTO MONDAY AND EVEN A BIT MORE ON
TUESDAY. TOUGH TO SAY IF THIS LOSS OF MOISTURE WILL BE ENOUGH TO
SLOW THE STILL FAVORABLE FLOW PATTERN FOR WEST COAST THUNDERSTORMS.
BEST GUESS IS THAT THE COLUMN WILL NOT DRY OUT ENOUGH TO SUPPRESS
CONVECTIVE COVERAGE AND CONSIDERED GOING WITH LIKELY POPS BOTH DAYS
DURING THE LATE AFTERNOON / EVENING. FOR NOW...KEPT THE LIKELY POPS
ALONG THE SUNCOAST ON MONDAY WITH HIGH END CHANCE (50-55%) RAIN
CHANCES FOR TAMPA BAY AND THE NATURE COAST...THEN HELD POPS AROUND
50% FOR ALL ON TUESDAY. COVERAGE COULD CERTAINLY BE HIGHER THAN
CURRENTLY FORECAST...ESPECIALLY ON MONDAY. THE NEXT SHIFT CAN TAKE
A CLOSER LOOK AT THE MOISTURE FIELDS IN THE NEXT MODEL CYCLE OR TWO
AND ADJUST UPWARDS IF NECESSARY.
&&
.LONG TERM (WEDNESDAY THROUGH NEXT SATURDAY)...
AN UPPER LEVEL RIDGE ACROSS FL FROM THE ATLANTIC WILL SLOWLY WEAKEN
THROUGH FRI AS AN UPPER LEVEL TROUGH MOVES FROM THE MIDWEST TO THE
SOUTHEAST U.S. THIS TROUGH CONTINUES EASTWARD ON SAT TO THE EASTERN
SEABOARD. AT THE SURFACE HIGH PRESSURE CENTERED OVER THE OPEN
ATLANTIC IN THE VICINITY OF 30 TO 35 NORTH LATITUDE RIDGES WEST TO
THE GULF COASTAL STATES THROUGH THE PERIOD...WITH A PREVAILING
EASTERLY/SOUTHEASTERLY BOUNDARY LAYER FLOW ACROSS THE AREA.
EXPECT A GENERAL SUMMERTIME PATTERN EACH DAY WITH SCATTERED TO
NUMEROUS MAINLY AFTERNOON THUNDERSTORMS. THE EAST AND SE FLOW WILL
KEEP THE WEST COAST SEA BREEZE CLOSE TO THE COAST FOR THE FIRST
COUPLE OF DAYS WITH THE HIGHEST COVERAGE OVER COASTAL COUNTIES.
THE EAST/SE FLOW WEAKENS SOME FOR THE END OF THE WEEK AND ALLOWS THE
WEST COAST SEA BREEZE TO PUSH SLIGHTLY FURTHER INLAND WITH MORE
UNIFORM COVERAGE AREA WIDE. TEMPERATURES RUN ABOVE NORMAL BY UP TO 1
TO 3 DEGREES.
&&
.AVIATION...
VFR CONDITIONS THROUGH MORNING WITH LIGHT VARIABLE/EASTERLY WINDS.
VFR CONTINUES ALTHOUGH TSRA MAY BEGIN TO IMPACT THE TERMINALS IN THE
AFTERNOON AND EARLY EVENING. WINDS BECOMES SE AND INCREASE SLIGHTLY
DURING THE MORNING THEN SHIFT TO ONSHORE DURING THE AFTERNOON.
&&
.MARINE...
THE RIDGE AXIS WILL REMAIN TO THE NORTH OF THE FORECAST WATERS
THROUGH THE EARLY PORTION OF THE WEEK. THIS POSITION WILL KEEP A
PERSISTENT EAST TO SOUTHEAST FLOW IN PLACE OVER THE FORECAST WATERS.
BEST CHANCES FOR THUNDERSTORMS WILL BE IN THE EARLY MORNING
HOURS...AND THEN AGAIN LATE IN THE AFTERNOON AND EVENING AS STORMS
MOVE EAST TO WEST OFFSHORE.
&&
.FIRE WEATHER...
THE SURFACE RIDGE AXIS TO OUR NORTH WILL KEEP A PERSISTENT EAST TO
SOUTHEAST FLOW GOING ACROSS THE FLORIDA PENINSULA THROUGH THE EARLY
PORTION OF THE WEEK. THIS EASTERLY FLOW WILL RESULT IN SEVERAL DAYS
OF ACTIVE AFTERNOON AND EVENING THUNDERSTORMS...ESPECIALLY ALONG THE
I-75 CORRIDOR. RELATIVE HUMIDITY VALUES ARE EXPECTED TO REMAIN WELL
ABOVE CRITICAL LEVELS AND NO SIGNIFICANT FIRE WEATHER CONCERNS ARE
IN THE FORECAST.
FOG POTENTIAL...NO SIGNIFICANT FOG IS EXPECTED THROUGH THE EARLY
PART OF THE WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 91 77 92 79 / 60 50 50 40
FMY 91 76 93 77 / 60 40 60 30
GIF 92 74 94 74 / 50 20 50 20
SRQ 91 76 93 76 / 60 60 60 40
BKV 91 73 93 74 / 60 50 50 40
SPG 90 79 91 80 / 60 60 50 40
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...RUDE
AREA FORECAST DISCUSSION...RESENT
NWS TAMPA BAY RUSKIN FL
445 AM EDT SUN AUG 18 2013
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS STILL SHOW AN AMPLIFIED UPPER
LEVEL PATTERN ACROSS THE EASTERN CONUS HIGHLIGHTED BY DEEP TROUGHING
ALONG AND JUST TO THE EAST OF THE MS RIVER VALLEY. SYNOPTIC
INFLUENCE FROM THIS FEATURE WILL RESULT IN THE POTENTIAL FOR SOME
VERY HEAVY RAINFALL ALONG THE NORTH-CENTRAL GULF COAST OVER THE NEXT
24 HOURS. HOWEVER...THIS ORGANIZED RAINFALL BANDING WILL BE HELD TO
OUR NORTHWEST BY A PROTECTIVE UPPER RIDGE THAT IS NOW IN PLACE OVER
THE FL PENINSULA. CLOSER TO THE SURFACE...THE RIDGE AXIS IS LOCATED
WELL TO OUR NORTH PROVIDING THE REGION WITH AN EAST TO SOUTHEAST
GRADIENT FLOW THAT WILL BE WITH US THROUGH THE EARLY PORTION OF THE
WEEK.
REGIONAL RADARS HAVE QUIETED DOWN CONSIDERABLY DURING THE PAST
SEVERAL HOURS WITH JUST A FEW TYPICAL NOCTURNAL MARINE SHOWERS WELL
OFFSHORE. THE RADAR SHOULD REMAIN ON THE QUIET SIDE THROUGH THE
MORNING HOURS OVER THE LAND MASS...HOWEVER THE INGREDIENTS ARE THERE
FOR ANOTHER ACTIVE THUNDERSTORM PATTERN ALONG THE FL WEST COAST
LATER THIS AFTERNOON AND EVENING. MORE ON THIS POTENTIAL IN THE
SHORT TERM DISCUSSION BELOW.
&&
.SHORT TERM (TODAY THROUGH TUESDAY)...
TODAY/TONIGHT...THE FINAL DAY OF THE WEEKEND WILL FEATURE GENERALLY
QUIET CONDITIONS FOR THE MORNING HOURS AS TEMPERATURES CLIMB TOWARD
THE LOWER 90S THROUGH A MIX OF SUN AND CLOUDS. THE LOW LEVEL
SYNOPTIC PATTERN WILL FEATURE EASTERLY FLOW THAT HAS BEEN A
RECURRING THEME THIS SUMMER AND IS THE FAVORED FLOW FOR AN ACTIVE
THUNDERSTORM PATTERN ALONG THE I-75 CORRIDOR DURING THE LATE
AFTERNOON AND EVENING HOURS. THERE MAY BE JUST ENOUGH BOUNDARY LAYER
FLOW TO KEEP ANY FEEBLE WEST COAST SEA-BREEZE FROM MOVING
INLAND...HOWEVER AT THE VERY LEAST WE WILL SEE A PARTIAL COLLAPSE OF
THE WIND FIELDS THIS AFTERNOON OVER THE NEARSHORE WATERS. THIS LACK
OF WIND WILL SET UP A SPEED CONVERGENCE ZONE NEAR THE COAST AND
SHOULD BE ENOUGH TO FORCE SCT-NMRS SHOWERS AND STORMS AFTER 3-4PM.
STORMS SHOULD GET GOING FIRST (EARLY TO MID AFTERNOON) OVER THE
SOUTHERN AND SOUTH-CENTRAL INTERIOR ZONES IN A SCT NATURE AND THEN
PROGRESS WEST AND NORTHWEST TOWARD THE TAMPA BAY AREA LATE IN THE
DAY (LATE AFTERNOON AND EARLY EVENING). IT WILL BE DURING THIS LATE
DAY / EVENING TIME FRAME THAT THE STORMS SHOULD BECOME MORE NMRS IN
NATURE. HAVE GONE WITH LIKELY 60% POPS ALONG THE ENTIRE I-75
CORRIDOR...HOWEVER...BASED ON THE LATEST HI-RESOLUTION CONVECTION
ALLOWING GUIDANCE SUITE...EVEN THIS COVERAGE MAY BE ON THE
CONSERVATIVE SIDE. GUIDANCE ALSO IS IN GOOD AGREEMENT THAT THE
ACTIVITY WILL LINGER WELL INTO THE EVENING...ESPECIALLY FOR THE
COASTAL ZONES. THIS IS AGAIN FAIRLY TYPICAL FOR THIS SYNOPTIC SETUP.
FINALLY AFTER 11 PM OR SO...WE SHOULD SEE THE LAST OF THE STORMS
DISSIPATE OR MOVE OFFSHORE...LEAVING THE LAND ZONES WITH A GENERALLY
DRY FORECAST FOR THE SECOND HALF OF THE NIGHT.
BOTTOM LINE...ANYONE WITH OUTDOOR OR TRAVEL PLANS ALONG THE I-75
CORRIDOR OR WITH NEAR SHORE BOATING PLANS FOR THE LATE DAY / EVENING
HOURS SHOULD BE PREPARED FOR RAPIDLY DEVELOPING CLUSTERS OF
STORMS.
MONDAY/TUESDAY...
OVERALL SYNOPTIC PATTERN CHANGES LITTLE FOR THE FIRST TWO DAYS OF
THE WORK WEEK. THE RIDGE ALOFT HOLDS POSITION...BUT NOT STRONG
ENOUGH TO SIGNIFICANTLY SUPPRESS CONVECTION...AND THE SURFACE RIDGE
POSITION KEEPS OUR FLOW FROM THE EAST. THE ONLY CHANGE IS A SLIGHT
DECREASE IN COLUMN MOISTURE INTO MONDAY AND EVEN A BIT MORE ON
TUESDAY. TOUGH TO SAY IF THIS LOSS OF MOISTURE WILL BE ENOUGH TO
SLOW THE STILL FAVORABLE FLOW PATTERN FOR WEST COAST THUNDERSTORMS.
BEST GUESS IS THAT THE COLUMN WILL NOT DRY OUT ENOUGH TO SUPPRESS
CONVECTIVE COVERAGE AND CONSIDERED GOING WITH LIKELY POPS BOTH DAYS
DURING THE LATE AFTERNOON / EVENING. FOR NOW...KEPT THE LIKELY POPS
ALONG THE SUNCOAST ON MONDAY WITH HIGH END CHANCE (50-55%) RAIN
CHANCES FOR TAMPA BAY AND THE NATURE COAST...THEN HELD POPS AROUND
50% FOR ALL ON TUESDAY. COVERAGE COULD CERTAINLY BE HIGHER THAN
CURRENTLY FORECAST...ESPECIALLY ON MONDAY. THE NEXT SHIFT CAN TAKE
A CLOSER LOOK AT THE MOISTURE FIELDS IN THE NEXT MODEL CYCLE OR TWO
AND ADJUST UPWARDS IF NECESSARY.
&&
.LONG TERM (WEDNESDAY THROUGH NEXT SATURDAY)...
AN UPPER LEVEL RIDGE ACROSS FL FROM THE ATLANTIC WILL SLOWLY WEAKEN
THROUGH FRI AS AN UPPER LEVEL TROUGH MOVES FROM THE MIDWEST TO THE
SOUTHEAST U.S. THIS TROUGH CONTINUES EASTWARD ON SAT TO THE EASTERN
SEABOARD. AT THE SURFACE HIGH PRESSURE CENTERED OVER THE OPEN
ATLANTIC IN THE VICINITY OF 30 TO 35 NORTH LATITUDE RIDGES WEST TO
THE GULF COASTAL STATES THROUGH THE PERIOD...WITH A PREVAILING
EASTERLY/SOUTHEASTERLY BOUNDARY LAYER FLOW ACROSS THE AREA.
EXPECT A GENERAL SUMMERTIME PATTERN EACH DAY WITH SCATTERED TO
NUMEROUS MAINLY AFTERNOON THUNDERSTORMS. THE EAST AND SE FLOW WILL
KEEP THE WEST COAST SEA BREEZE CLOSE TO THE COAST FOR THE FIRST
COUPLE OF DAYS WITH THE HIGHEST COVERAGE OVER COASTAL COUNTIES.
THE EAST/SE FLOW WEAKENS SOME FOR THE END OF THE WEEK AND ALLOWS THE
WEST COAST SEA BREEZE TO PUSH SLIGHTLY FURTHER INLAND WITH MORE
UNIFORM COVERAGE AREA WIDE. TEMPERATURES RUN ABOVE NORMAL BY UP TO 1
TO 3 DEGREES.
&&
.AVIATION...
VFR CONDITIONS THROUGH MORNING WITH LIGHT VARIABLE/EASTERLY WINDS.
VFR CONTINUES ALTHOUGH TSRA MAY BEGIN TO IMPACT THE TERMINALS IN THE
AFTERNOON AND EARLY EVENING. WINDS BECOMES SE AND INCREASE SLIGHTLY
DURING THE MORNING THEN SHIFT TO ONSHORE DURING THE AFTERNOON.
&&
.MARINE...
THE RIDGE AXIS WILL REMAIN TO THE NORTH OF THE FORECAST WATERS
THROUGH THE EARLY PORTION OF THE WEEK. THIS POSITION WILL KEEP A
PERSISTENT EAST TO SOUTHEAST FLOW IN PLACE OVER THE FORECAST WATERS.
BEST CHANCES FOR THUNDERSTORMS WILL BE IN THE EARLY MORNING
HOURS...AND THEN AGAIN LATE IN THE AFTERNOON AND EVENING AS STORMS
MOVE EAST TO WEST OFFSHORE.
&&
.FIRE WEATHER...
THE SURFACE RIDGE AXIS TO OUR NORTH WILL KEEP A PERSISTENT EAST TO
SOUTHEAST FLOW GOING ACROSS THE FLORIDA PENINSULA THROUGH THE EARLY
PORTION OF THE WEEK. THIS EASTERLY FLOW WILL RESULT IN SEVERAL DAYS
OF ACTIVE AFTERNOON AND EVENING THUNDERSTORMS...ESPECIALLY ALONG THE
I-75 CORRIDOR. RELATIVE HUMIDITY VALUES ARE EXPECTED TO REMAIN WELL
ABOVE CRITICAL LEVELS AND NO SIGNIFICANT FIRE WEATHER CONCERNS ARE
IN THE FORECAST.
FOG POTENTIAL...NO SIGNIFICANT FOG IS EXPECTED THROUGH THE EARLY
PART OF THE WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 91 77 92 79 / 60 50 50 40
FMY 91 76 93 77 / 60 40 60 30
GIF 92 74 94 74 / 50 20 50 20
SRQ 91 76 93 76 / 60 60 60 40
BKV 91 73 93 74 / 60 50 50 40
SPG 90 79 91 80 / 60 60 50 40
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
350 AM EDT SUN AUG 18 2013
.DISCUSSION...
TODAY-TONIGHT...
AN H30-H20 JET EXTENDING FROM THE LWR MS VALLEY TO CAPE COD WILL
SHIFT TO THE MID ATLC/CANADIAN MARITIMES...ALLOWING THE SUBTROPICAL
ATLC RIDGE AXIS TO ANCHOR ITSELF OVER THE DEEP SOUTH. THIS POSITION
WILL GENERATE A DEEP AND STEADY SERLY FLOW ACRS CENTRAL FL.
THE SE BREEZE WILL FAVORS THE WEST PENINSULA FOR DIURNAL CONVECTION
BUT WILL ALLOW FOR SLIGHTLY HIGHER COVERAGE OVER THE INTERIOR
COUNTIES AS WELL. RUC ANALYSIS SHOWS THE DRY AIR THAT WAS
APPROACHING THE SRN BAHAMAS SAT MORNING HAS NOT PUSHED AS FAR WEST
AS ANTICIPATED...H100-H70 AND H85-H50 MEAN RH LVLS OVER THE SW
ATLC/NRN BAHAMAS IS BTWN 70-85PCT...SUFFICIENT TO SUPPORT SCT
COVERAGE AREAWIDE.
INDEED...A CLUSTER OF SHRAS HAS PERSISTED JUST DOWNWIND OF THE NRN
BAHAMAS SINCE LATE LAST NIGHT...OWNING LARGELY TO A LCL POCKET OF
ENHANCED H85-H50 VORTICITY. WHILE THIS MID LVL ENERGY HAS BEEN
SLOWLY WEAKENING WITH TIME...SCT SHRAS HAVE PERSISTED IN THE SERLY
FLOW LONG ENOUGH TO PUSH ONSHORE. FURTHERMORE...GFS HAS BACKED OFF
ITS PREVIOUS DRY TREND...KEEPING PWAT VALUES ARND 2.0" THRU THE DAY
BEFORE DIMINISHING TO ARND 1.7" BY DAYBREAK MON.
THE MID LVL VORT GRADIENT IS RATHER TIGHT AS THE AFOREMENTIONED
IMPULSE IS PARKED NEXT TO A TORPID AIRMASS OVER THE W PENINSULA.
WHILE THIS MAY GIVE A COUPLE OF STORMS SOME PUNCH...OVERALL STORM
POTENTIAL WILL REMAIN LOW AS THE THERMODYNAMIC PROFILE REMAINS
WEAK...H50 TEMPS BTWN -6C AND -7C...H85-H50 BLO 6.0C/KM. ANY STRONG
ACTIVITY WOULD TEND TO FORM ALONG AND W OF THE FL TURNPIKE AS THE
DEEP SERLY FLOW WILL PUSH THE SEA BREEZE PRETTY FAR INLAND BY THE
PEAK CONVECTIVE HRS OF 18Z-24Z.
GIVEN THE DEPTH AND STEADY STRENGTH OF THE SERLY FLOW...MOS GUIDANCE
POPS LOOK A BIT ON THE HIGH SIDE. WILL CAP POPS AT 50PCT OVER THE
INTERIOR FROM OSCEOLA CO. NWD...40PCT ELSEWHERE. ONSHORE FLOW WILL
KEEP MAX TEMPS IN THE U80S/L90 ALONG THE COAST...INTERIOR WARMING TO
THE L/M90S. MIN TEMPS L/M70S.
MON-SAT...
THE UPPER LEVEL AND SURFACE RIDGE AXES REMAIN NORTH OF CENTRAL
FLORIDA THROUGH SATURDAY. DEEP LAYER EAST TO SOUTHEAST FLOW OFF THE
ATLANTIC WILL BE THE NORM THROUGH THE BALANCE OF THE FORECAST CYCLE.
TIME HEIGHT CROSS SECTIONS FOR THE SOUTHERN COASTAL SITES SHOW BULK
OF THE MOISTURE FROM 850MB/APPROX 5000 FEET AND BELOW. THE
COMBINATION OF WEAK UPPER LEVEL DISTURBANCES MOVING EAST TO WEST IN
THE UPPER LEVEL FLOW AND LIMITED DEPTH OF MOISTURE RESULT IN A 30 TO
40 PERCENT CHANCE OF AFTERNOON SHOWERS AND LIGHTNING STORMS OVER THE
INTERIOR. LINGERING STORMS AND SHOWERS UNTIL MID TO LATE EVENING
THEN PRECIP FREE OVER THE INTERIOR. THE EAST TO SOUTHEAST FLOW IS
DEEP ENOUGH WITH WINDS THROUGH 10000 FEET STRONG ENOUGH TO PUT IN A
SLIGHT CHANCE OF COASTAL SHOWERS.
HIGHS EACH DAY SHOULD RANGE FROM AROUND 90 AT THE COAST TO THE LOW
90S FOR THE INTERIOR. MORNING LOWS RANGE FROM THE MID 70S FOR THE
INTERIOR TO THE UPPER 70S AT THE COAST WITH SOME AROUND 80 DEGREE
READINGS AT THE BEACHES.
&&
.AVIATION...
VFR ALL SITES UNLESS OTHERWISE NOTED.
THRU 18/15Z...ISOLD MVFR SHRAS S OF KMLB. BTWN 18/15Z-18/19Z...SCT
MVFR SHRAS/IFR TSRAS DVLPG ALONG THE COAST AND MVG W-NW 10-15KTS.
BTWN 18/19Z-18/23Z...INTERIOR SITES SCT MVFR SHRAS/IFR TSRAS...
COASTAL SITES ISOLD MVFR SHRAS/ISOLD TSRAS WITH OCNL E/SE SFC WND
G20-22KTS. BTWN 18/23Z-19/03Z...CHC MVFR SHRAS/IFR TSRAS INTERIOR
SITES...SLGT CHC COASTAL SITES. AFT 19/03Z...SLGT CHC MVFR SHRAS
COASTAL SITES.
&&
.MARINE...
TODAY-TONIGHT...SUBTROPICAL RIDGE AXIS WILL CONSOLIDATE ITSELF OVER
THE DEEP SOUTH...RESULTING IN A GENTLE TO MODERATE E/SE BREEZE ACRS
THE LCL ATLC WATERS. THE ERLY FETCH EXTENDS WELL INTO THE W ATLC AND
WILL PUSH A 1-2FT LONG PD SWELL INTO THE E FL COAST...PUSHING SEAS
INTO THE 2-3FT RANGE NEARSHORE...3-4FT OFFSHORE. CHOPPY SHORT PD
WIND WAVES WILL PREVAIL S OF VERO BEACH DUE TO THE SHADOW EFFECT OF
GRAND BAHAMA ISLAND. SCT SHRAS AND ISOLD TSRAS.
MON-THU...THE ATLANTIC RIDGE WILL REMAIN NORTH OF THE EAST CENTRAL
FLORIDA COASTAL WATERS. A LONG 10 TO 15 KNOT EASTERLY FLOW AND FETCH
WILL BE FAVORABLE FOR SEAS 4 FEET OR LESS WITH A SMALL LONG PERIOD
SWELL COMPONENT.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 89 78 90 76 / 40 20 40 20
MCO 93 76 93 75 / 50 30 40 20
MLB 90 78 90 78 / 40 20 30 20
VRB 89 78 90 77 / 40 20 30 20
LEE 91 76 93 77 / 50 40 50 20
SFB 93 77 93 77 / 50 30 40 20
ORL 92 77 93 77 / 50 30 40 20
FPR 89 78 90 76 / 40 20 30 20
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM/IMPACT WX...WIMMER
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
208 AM EDT Sun Aug 18 2013
.NEAR TERM [Through Today]...
The main concern for today is the potential for additional flooding.
We are watching with interest a fairly well defined MCS moving
northeastward south of Mobile this morning. Some of the models may
be having some trouble with this feature as the NAM appears to be on
the weak side and our local 18/00z ARW run does not see this feature
very well (uses 00z NAM boundary conditions). The 18/00z GFS does
see this feature, but based on recent satellite/radar trends, it may
be just a tad too far west with its axis of heaviest precip
associated with it. This raises some concern about the potential for
additional flash flooding over the western portions of the forecast
area today due to low flash flood guidance values if this feature
moves just slightly more to the east. There is also ongoing areal
flooding in Walton county, so flash flood guidance values are
probably overdone in that county by quite a bit.
The plan of action right now is to observe the trends in the MCS on
satellite/radar over the next few hours and wait for some additional
pieces of hi-res guidance to come in before making a decision about
whether or not to re-issue the flash flood watch over the western
areas. From a model perspective, the trends in the HRRR as well as
our local 18/06z ARW run will be important as our 06z ARW uses the
00z GFS for boundary conditions and may have a better handle on this
feature than our 00z run.
&&
.SHORT TERM [Tonight through Tuesday]...
The large scale pattern continues to shift tonight. This is
highlighted by ridging over west half of Conus, Ern trough lifting
Newd with low opening up into OH Valley, and deep layer Atlc ridge
building WSW in its place into SE states. At surface, building
ridge aids in weakening quasi-stnry front and nudging it Nwd ending
its local focus for showers and thunderstorms. Low level flow also
begins to back to ESE.
During the rest of the period, Ern trough lifts further Newd and
flattens out. This allows Wrn and Atlc ridges to advance Ewd and Wwd
respectively bridging by end of period cutting off tropical plume.
This shifts steering flow to ELY allowing local gradients to tighten
some. By Tues, front has largely dissipated with surface high
anchored over NE SC/NW GA thus we transition to a more typical
summertime pattern with Gulf and Atlc seabreeze/mesoscale boundary
generated aftn and eve convection.
Will go with 30-40% tonight, 30-60% on Mon and 30-50% Tues E-W POP
gradient. Min temps in low 70s tonight. Highs Mon and Tues upper 80s
NW to low 90s SE with Max hear indices around 100 degrees.
&&
.LONG TERM [Tuesday Night 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.
&&
.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.
&&
.AVIATION...
[Through 06z Monday] MVFR to IFR conditions are expected to develop
during the early morning hours this morning. Another round of
convection is expected across the area later today, most likely at
KDHN and KECP.
&&
.FIRE WEATHER...
There are currently no fire weather concerns with moist conditions
in place.
&&
HYDROLOGY...
Several local river systems have had (or will soon have) 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. The next few river model runs
should be able to focus on the main threat areas, since these models
will have a more complete picture of the area rainfall the past few
days. 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 89 73 91 73 91 / 60 30 50 30 40
Panama City 87 76 88 76 87 / 60 40 50 30 50
Dothan 86 72 89 72 90 / 70 40 60 30 50
Albany 87 72 90 72 91 / 60 30 60 40 50
Valdosta 89 72 91 72 92 / 50 30 50 40 40
Cross City 90 72 91 72 92 / 50 30 40 40 30
Apalachicola 86 77 86 77 86 / 50 40 50 30 40
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
AVIATION/FIRE WX/NEAR TERM...DVD
HYDROLOGY...DVD
Long Term...Lamers/Moore
Short Term/Marine...Block
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
137 AM EDT SUN AUG 18 2013
.UPDATE...
/ISSUED AT 1010 PM EDT SAT AUG 17 2013/
HAVE TWEAKED THE POPS THROUGH 06Z BASED ON RADAR. SINCE HEAVY RAIN
HAS MOVED EAST OF THE CWA FOR THE TIME BEING...HAVE REMOVED HEAVY
RAIN WORDING FOR THE EVENING. NOT SURE HOW RAIN WILL DEVELOP AFTER
06Z SO HAVE MADE NO CHANGES FOR THE 06Z TO 12Z GRIDS. WILL LET FLOOD
WATCH GO ON UNTIL EXPIRATION AT 12Z. FLASH FLOOD GUIDANCE IS SO LOW
IN THE WATCH AREA THAT ANOTHER ROUND OF SHOWERS COULD CAUSE
PROBLEMS.
41
.PREVIOUS...
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...
06Z UPDATE...
LIFR/IFR CIGS/VIS HAVE SETTLED ACROSS MOST TAF SITES EARLY THIS
MORNING...AND THIS CONDITIONS WILL LIKELY PERSIST THROUGH LATE
MORNING...BEFORE IMPROVING TO LOW MVFR CIGS FOR THE AFTERNOON. GFS
HOLDS THE WEDGE IN OVER THE ATLANTA TAF SITES THROUGH TONIGHT...
WHILE THE NAM SHOWS A WARM/SOUTHERLY WIND FLOW SPREADING NORTH OF
ATLANTA DURING THE AFTERNOON. WILL LEAN TOWARD THE GFS AND HOLD
WINDS ESE AT 8-10KTS TODAY WITH PREVAILING -SHRA AS AMPLE MOISTURE
CONTINUES TO OVER THE COOL EASTERLY SURFACE FLOW. MAY HERE A RUMBLE
OF THUNDER DURING THE AFTERNOON AS THE WARM FRONT NEARS ATL...BUT
WILL JUST MENTION -SHRA`S. EXPECT IFR CIGS TO RETURN THIS EVENING
AND PERSIST OVERNIGHT.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM TO HIGH ON ALL ELEMENTS.
39
&&
.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...41
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
212 AM EDT SUN AUG 18 2013
.SYNOPSIS...
LOW PRESSURE MOVES SLOWLY NORTHEAST ALONG THE MID ATLANTIC COAST
THIS WEEKEND. HIGH PRESSURE RETURNS MONDAY NIGHT THROUGH
WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
LATEST ANALYSIS SHOWED HI PRES CNTRD OVR NEW ENGLAND...WITH WEAK
LO PRES CNTRD JUST SW OF CAPE HATTERAS. CURRENT FCST IN GOOD
SHAPE...AS LATEST RDR INDICATED AREAS OF RAIN N OF THE LO WERE
SPREADING FARTHER NWRD INTO THE CWA. 00Z RUC IN GENERAL AGREEMENT
WITH THE GFS SHOWING THE WEAK LO PRES AREA MOVNG NE OVRNGT TO A
POSITION JUST E OF VA BEACH BY 12Z SUN. THIS WILL RESULT IN AREAS
OF RAIN SHIFTING INTO THE NRN HALF OF THE REGION LATER TNGT INTO
SUN MORNG. SO...WILL HAVE LIKELY TO CAT POPS EVERYWHERE. LO TEMPS
RANGING FM THE MID 60S TO ARND 70.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
LO LVL WEDGE TO HANG ON INTO SUN NGT. LO PRES CONTS TO TRACK NE
OFF THE VA/MD CST SUN...THEN NE AWAY FM THE RGN SUN NGT INTO MON.
RA ASSOCIATED W/ THAT LO TO MOVE OVR MNLY ERN PORTIONS OF THE FA
SUN MRNG BEFORE EXITING. MDLS SHOWING AREA OF RA TO PUSH NWD
THROUGH WRN HALF OF VA SUN/SUN NGT. MUCH OF THE FA BY SUN AFTN
THROUGH SUN NGT MAY BE LEFT W/ JUST CLDNS AND ONLY SPOTTY RA. BY
MON...TROUGH ALOFT APPROACHES FM THE W...CROSSING THE RGN LT MON
INTO MON NGT POSSIBLY ENHANCING TSTM PTNTL. ON TUE...SFC HI PRES
TAKES UP RESIDENCE INVOF CAROLINAS/FAR WRN ATLC...W/ WNW FLO
ALOFT. TSTM PTNTL ON TUE LWR ACRS ALL BUT FAR SRN VA/NE NC...W/
OVERALL WX CONDS RETURNING TO THOSE MORE TYPICAL OF AUG.
HI TEMPS SUN FM THE M70S NW TO L80S SE. LO TEMPS SUN NGT FM THE
M60S TO ARND 70F. HI TEMPS MON IN THE L/M80S. HI TEMPS TUE IN THE
M/U80S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
RATHER BENIGN WEATHER IN STORE AS A RATHER FLAT/ZONAL PATTERN
TAKES PLACE DURING THE MID TO LATE WORK WEEK TIMEFRAME. SURFACE
HIGH PRESSURE BECOMES CENTERED JUST SOUTH OF THE AREA ON WED/THU
AND PUSHES THE STALLED COASTAL BOUNDARY FARTHER SOUTH INTO THE
CAROLINAS. A FEW SPOKES OF MOISTURE COULD SNEAK UP INTO NE NC AND
POSSIBLY FAR SRN VA ON WEDNESDAY AND TOUCH OFF DIURNALLY-DRIVEN
AFTERNOON SHOWERS AND THUNDERSTORMS. FOR THURSDAY...A THERMAL
TROUGH DEVELOPS AND SHOULD HELP SHOWERS AND STORMS DEVELOP FURTHER
NORTH INTO CTRL VA THURSDAY AFTERNOON. A LOW PRESSURE SYSTEM
CROSSING THROUGH NEW ENGLAND IS THEN EXPECTED TO DRAG A FRONT
ACROSS THE REGION ON FRIDAY...FOCUSING BETTER PRECIP CHANCES ALONG
THIS BOUNDARY. BEHIND THE FRONT...HIGH PRESSURE RETURNS TO THE
AREA WITH DRIER AND SLIGHTLY COOLER TEMPS ANTICIPATED. HIGHS WILL
GENERALLY BE IN THE MID TO UPPER 80S AND LOWS IN THE 60S (LOWER
70S AT TIMES IN FAR SE VA/NE NC).
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
SFC LOW HAS LOCATED OVER NE NC (PER LATEST SFC OBS) AS HIGH
PRESSURE REMAINS WEDGED INTO CNTRL VA. LATEST RADAR TRENDS SHOW
BROAD AREA OF SCATTERED TO NUMEROUS SHOWERS LIFTING THROUGH THE
LOCAL AREA IN ADVANCE OF THE LOW...BUT LESS COVERAGE OBSERVED OVER
NC EARLY THIS MORNING. SOME OF THE SHOWERS HAVE BEEN HEAVY WITH
SEVERAL SITES REPORTING IFR VSBYS. IN ADDITION...ABUNDANT MOISTURE HAS
RESULTED IN IFR OVC SKIES WITH DECKS GENERALLY 700 TO 1500
FT...EXPECT THE ERN SHORE WHERE CIGS GENERALLY 4 TO 6K FT. SOME
LOCALES HAVE DROPPED TO LIFR CIGS. ALL TAF SITES FORECAST TO DROP
BELOW IFR CIGS THROUGH AT LEAST MID MORNING...AND POSSIBLY CONTINUING
THROUGH EARLY AFTERNOON. THE EXCEPTION WILL BE THE ERN SHORE AND
TAF SITE KSBY. MET GUIDANCE REMAINS RATHER PESSIMISTIC...KEEPING
IFR CIGS THROUGH THE ENTIRE DAY AND INTO TONIGHT (SUN NIGHT).
HOWEVER...WILL IMPROVE CONDITIONS TO MVFR MID TO LATE MORNING
(CIGS 1500-2500 FT AGL) AND INTO THE AFTERNOON AS THE SFC LOW LIFTS
OFFSHORE. WINDS THIS MORNING WILL BE FROM THE E/NE...GENERALLY
AOB 10 KT. THE EXCEPTION WILL BE ALONG THE COAST AS WINDS COULD
GUST UP TO 20 KT. AS THE LOW LIFTS OFFSHORE THROUGH THE
AFTERNOON...WINDS WILL BACK TO THE N-NW AOB 10 KT. EXPECT SHOWERS
TO DIMINISH THROUGH MID MORNING...WITH ONLY ISOLATED TO WIDELY
SCATTERED SHOWERS THIS AFTERNOON AS THE COASTAL FRONT REMAINS
ALONG THE COAST.
STRATUS AND/OR FOG IS POSSIBLE MONDAY MORNING AS THERE IS LITTLE
CHANGE IN THE AMBIENT AIRMASS. A TROUGH SWINGS ACROSS THE AREA
MONDAY AFTERNOON PRODUCING A CHANCE OF SHOWERS AND TSTMS. CONDITIONS
IMPROVE THROUGH MIDWEEK.
&&
.MARINE...
A COASTAL LOW PRESSURE SYSTEM WILL PUSH NORTHEAST UP THE CAROLINA
COASTS AND INTO AREA WATERS TONIGHT AS IT TRAVELS ALONG A STALLED
BOUNDARY. THE COMBINATION OF A TIGHTENING SURFACE PRESSURE
GRADIENT AND COOL MARINE AIR MOVING OVER WARMER WATER TEMPS WILL
RESULT IN BREEZY AND PERSISTENT NE WINDS TONIGHT INTO SUNDAY
MORNING. A SURGE OF 15-20 KT WINDS THIS EVENING INTO SUNDAY
MORNING WILL INCREASE WAVES IN THE CHES BAY TO 4 FT (LOCALLY UP TO 5
FT NEAR THE MOUTH OF THE BAY)...AND INCREASE SEAS TWD 5 FT CLOSER
TO 20 NM FROM CAPE CHARLES LIGHT TO CURRITUCK LIGHT. SCA FLAGS
HAVE BEEN ISSUED FOR THE CHES BAY AND THE RIVERS AS WELL AS THE SRN
COASTAL WATERS THROUGH EARLY SUNDAY MORNING. AS THE COASTAL LOW
PUSHES NORTHEAST OVERNIGHT...THE TIGHTENED PRESSURE GRADIENT WILL
SHIFT NORTHEAST AND CAUSE WIND SPEEDS TO DIMINISH. AS THIS
OCCURS...SEAS WILL ALSO BEGIN TO SUBSIDE BELOW 5 FT JUST BEFORE
DAYBREAK. CHES BAY WILL BE SLOWER TO RESPOND TO SUBSIDING
CONDITIONS AND SCA FLAGS WILL PERSIST HERE THROUGH AT LEAST MID
MORNING BEFORE WINDS/WAVES TAPER OFF.
LOW PRESSURE CONTINUES ITS NORTHEAST TRACK DURING THE REST OF
SUNDAY AND AWAY FROM THE WATERS BY MONDAY MORNING. HIGH PRESSURE
RETURNS TO THE MID ATLANTIC REGION TUESDAY AND WEDNESDAY. FOR
SUNDAY...WINDS WILL CONTINUE TO BE N-NE AOB 15 KT NORTH AND
AOB 10 KT SOUTH. AFTER THAT...WINDS WILL GRADUALLY SHIFT AROUND TO
THE WEST AOB 10 KT WITH WAVES/SEAS AVERAGING 1-3 FT.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EDT THIS AFTERNOON FOR
ANZ630>632-634>636-638-654.
SMALL CRAFT ADVISORY UNTIL 8 AM EDT THIS MORNING FOR ANZ656.
SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 6 PM EDT THIS
EVENING FOR ANZ650-652.
&&
$$
SYNOPSIS...ALB
NEAR TERM...ALB/TMG
SHORT TERM...ALB
LONG TERM...BMD
AVIATION...SAM
MARINE...SAM/JAB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
346 AM EDT SUN AUG 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 344 AM EDT SUN AUG 18 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW UPR RDG STRETCHING
FM THE NCENTRAL PLAINS INTO THE UPR LKS TO THE S OF ZONAL FLOW OVER
SRN CANADA AND N OF CLOSED LO IN THE MID MS RIVER VALLEY. THE CWA IS
DOMINATED BY THE SW LLVL FLOW ON THE WRN FLANK OF SFC HI PRES OVER
THE NE CONUS. LOCAL 00Z RAOBS DEPICT SHARP SUBSIDENCE INVRN BTWN
H75-85 WITH DRY MID LVLS UNDER THE UPR RDG AXIS. THERE IS A SHRTWV
TRACKING EWD WITHIN THE ZONAL FLOW AND OVER A STNRY FNT IN
ONTARIO...BUT ONLY SOME HI CLDS ON THE SRN EDGE OF THIS DISTURBANCE
ARE SPILLING INTO LK SUP. THE SW FLOW ARND THE SFC HI TO THE E IS
TAPPING FAIRLY DRY LLVL AIR SHOWN ON THE 00Z MPX/GRB RAOBS...WHERE
THE H85 DEWPT WAS 7C AT BOTH SITES. MORE HUMID AIR IS PRESENT OVER
THE CENTRAL HI PLAINS...WHERE THE 00Z H85 DEWPT WAS 16C AT NORTH
PLATTE NEBRASKA.
MAIN FCST CONCERNS IN THE SHORT TERM WL BE TEMPS WITH SPRAWLING RDG
DOMINATING. LATER TNGT...FOCUS SHIFTS TO WHETHER THERE MIGHT BE A
FEW SHRA/TS OVER THE FAR WRN CWA AS SHRTWV EMBEDDED IN ZONAL FLOW
ALF TAPS SOME OF THE MORE HUMID H85 AIR IN THE CENTRAL HI PLAINS.
TDAY...WITH UPR RDG/SUBSIDENCE INVRN/MID LVL DRY AIR LINGERING OVER
UPR MI...EXPECT ANOTHER DRY DAY FOR UPR MI WITH NOTHING MORE THAN
SOME DIURNAL CU. H85 TEMPS ARE FCST TO BE 14-15C BY 00Z MON...UP TO
1C HIER THAN AT 00Z SUN. MIXING TO H8 AS OBSVD YDAY YIELDS HI TEMPS
80-85 AWAY FM THE MODERATING INFLUENCE OF LK MI IN CONTINUED LLVL SW
FLOW. THE DEEP MIXING MIGHT ALLOW FOR SOME GUSTS UP TO 20 MPH OVER
MAINLY THE NW CWA WHERE THE PRES GRADIENT WL BE A BIT TIGHTER/H925
WIND UP TO 20-25KTS. WITH MIN RH DROPPING TO ARND 35 PCT AS DEWPTS
MIX OUT DOWN TO THE LO 50S AND RECENT DRYNESS...FIRE WX CONCERNS WL
BE A BIT ELEVATED IN THAT AREA.
TNGT...MODELS REMAIN CONSISTENT SHOWING SHRTWV EMBEDDED IN ZONAL
FLOW OVER SRN SASKATCHEWAN SHIFTING ESEWD TOWARD THE UPR LKS AND
WEAKENING THE UPR RDG...WITH 00Z-12Z MON H5 HGT FALLS UP TO 40M OVER
THE CWA. AT THE SAME TIME...PERSISTENT SW FLOW IS PROGGED TO TAP
SOMEWHAT MORE HUMID H85 AIR NOW SHOWING UP IN THE CENTRAL PLAINS...
WITH FAIRLY VIGOROUS H85 THETA E ADVECTION INTO THE WRN CWA AFT 06Z.
THE MAIN PROBLEM FOR SHRA/TS DVLPMNT IS THE VERY DRY/STABLE
ANTECEDENT AIRMASS. IN FACT...NAM/GFS FCST SDNGS SHOW THE PROFILE
REMAINING TOO STABLE FOR CONVECTION EVEN OVER THE W EXCEPT PERHAPS
AT IWD TOWARD 12Z. ALTHOUGH THE BULK OF ANY SHRA/TS WL LIKELY BE TO
THE NW TOWARD LOWER HGTS/STNRY FNT IN ONTARIO...OPTED TO RETAIN
GOING SCHC POPS REACHING THE WRN LAND CWA IN THE 09Z-12Z TIME GIVEN
THE ARRIVAL OF THE HIER H85 THETA E...SSI FALLING TO NEAR -2C AND
AXIS OF H85-5 QVECTOR CNVGC FCST TO REACH THIS AREA IN THE 06Z-12Z
TIME. COMBINATION OF INCRSG PWAT TOWARD 1.5 INCH LATE OVER THE W AND
STEADY WSW H925 FLOW WITH WINDS UP TO 25-30KTS WL HOLD MIN TEMPS UP
OVER THE NW IN THE DOWNSLOPE AREAS NEAR LK SUP. BEST CHC FOR SOME
MINS IN THE COOLER 50S WL BE OVER THE INTERIOR SCENTRAL AND E...
WHERE WINDS WL BE LIGHTER AND DRIER AIR WL LINGER LONGEST.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 344 AM EDT SUN AUG 18 2013
MOST ATTENTION IN THE LONG TERM WAS FOCUSED ON TEMPS /MAINLY
THROUGH MID WEEK/ AND PRECIP /MAINLY WED INTO WED NIGHT/ WITH A COLD
FRONT MOVING INTO THE CWA.
LARGE SCALE WISE...AT 12Z MON...THERE WILL BE UPPER LEVEL HIGH
PRESSURE OVER MUCH OF THE CONUS...WITH ZONAL FLOW OVER CANADA. AT
THE SFC...THE CWA WILL BE BETWEEN HIGH PRESSURE COVERING MOST OF THE
CONUS AND A TROUGH OVER SASKATCHEWAN/MANITOBA. A SHORTWAVE WILL BE
OVER THE FAR WRN CWA AT 12Z MON...AND WILL TO THE CENTRAL CWA BY 18Z
MON. PRECIP WITH THE SHORTWAVE IS UNCERTAIN...BUT WILL CONTINUE TO
FAVOR LESSER PRECIP SOLUTIONS DUE TO THE SHORTWAVE PASSING BEFORE
PEAK HEATING AND THAT IT WILL BE PUSHING INTO HIGH PRESSURE.
STILL...MAY BE SOME ISOLATED SHOWERS/THUNDERSTORMS THAT TRY TO POP
UP. HIGHS WILL BE IN THE UPPER 70S TO MID 80S ON MON AS 850MB TEMPS
INCREASE TO AROUND 15C.
THE ZONAL FLOW WILL CONTINUE TO PUSH DYING PIECES OF ENERGY INTO THE
CWA TUE...BUT SAME STORY AS MON WITH THE SHORTWAVE PUSHING INTO THE
HIGH PRESSURE. BY 18Z TUE...850MB TEMPS WILL BE AROUND 18C...SO
HIGHS WILL BE EVEN WARMER IN THE 80S TO AROUND 90.
THE BIGGER QUESTION FOR THE FORECAST COMES ON WED AS A SFC
TROUGH/COLD FRONT MOVES INTO THE CWA LATER IN THE DAY INTO THE EARLY
OVERNIGHT HOURS WED NIGHT. GIVEN FORCING COMBINED WITH INSTABILITY
/CAPE VALUES AROUND 1500-2500 J/KG/ SHOULD LEAD TO SHOWERS AND
THUNDERSTORMS MOVING INTO/DEVELOPING ACROSS THE CWA. INCREASED POPS
SOME AS CONFIDENCE CONTINUES TO IMPROVE. WITH THE INSTABILITY AND
0-6KM BULK SHEAR AROUND 20KTS...A SEVERE STORM OR TWO CANNOT BE
RULED OUT...BUT IT IS STILL PRETTY EARLY FOR THAT DETERMINATION.
HIGHS ON WED LOOK TO BE SIMILAR TO TUESDAY.
POST COLD FROPA...THURSDAY IS THE MOST PREDICTABLE DAY AS COOLER
850MB TEMPS AROUND 14C WILL BE OVER THE CWA. THIS SHOULD RESULT IN
HIGHS IN THE 70S TO AROUND 80 /WARMEST SCENTRAL/. CONFIDENCE
DECREASES SIGNIFICANTLY AFTER THURSDAY AS MODELS SHOW WIDELY
DIFFERENT SOLUTIONS...MAINLY FOR TEMPS. THE ECMWF BRINGS A STRONG
UPPER RIDGE OVER THE REGION FRI INTO SAT...WHICH WOULD RESULT IN
VERY WARM TEMPS AGAIN. THE GFS KEEP THE STRONGEST PART OF THAT RIDGE
WELL TO OUR W...SO TEMPS ARE NOT AS WARM. WILL JUST GO WITH A
CONSENSUS OF MODEL GUIDANCE AT THIS TIME AND FOCUS ON SHORTER TERM
ISSUES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 126 AM EDT SUN AUG 18 2013
WITH RELATIVELY DRY LOW-LEVELS...VFR CONDITIONS WILL PREVAIL THRU
THE FCST PERIOD AT KIWD/KCMX/KSAW. ONLY ITEM OF NOTE IS THAT
INCREASING SW WINDS ABOVE NOCTURNAL INVERSION EARLY THIS MRNG WILL
APPROACH LLWS CRITERIA.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 344 AM 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 WINDS UP TO 20-25 KTS MAY
IMPACT THE W AND NCENTRAL TONIGHT UNDER A SHARPER PRES GRADIENT
AHEAD OF AN APPROACHING DISTURBANCE. THE ARRIVAL OF MORE HUMID AIR
FOR TUE/WED WILL RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE
WATERS. ANY FOG WILL DISSIPATE ON 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...TITUS
LONG TERM...KC
AVIATION...VOSS
MARINE...KC
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
131 AM EDT SUN AUG 18 2013
.SYNOPSIS...
LOW PRESSURE WILL EXIT NE OF THE AREA THIS EVENING...AND OFF THE
OUTER BANKS BY DAYBREAK SUNDAY. A FRONTAL SYSTEM DRAPED ALONG THE
IMMEDIATE COAST OF THE CAROLINAS AND HIGH PRESSURE RIDGING
SOUTHWEST ACROSS THE CENTRAL CAROLINAS...WILL BOTH PERSIST INTO
EARLY NEXT WEEK. THE FRONT WILL FINALLY DISSIPATE BY MIDWEEK WITH
WEAK HIGH PRESSURE REMAINING ACROSS THE AREA. THE CHANCE FOR
CONVECTION WILL EXIST EACH AFTERNOON AND EVENING THROUGH THE MID
WEEK PERIOD OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 1:30 AM SUNDAY...NO CHANGES TO THE FORECAST WITH THE LATEST
UPDATE. PREVIOUS DISCUSSION FOLLOWS:
MODELS...HAVING A PROBLEM WITH THE CLUSTER OF SHOWERS AND STORMS
JUST WEST OF THE GA-SC BORDER. HRRR SEEMS TO HAVE CAUGHT ON
SOMEWHAT...THE GFS SHOWS A VERY WEAK S/W TROF OR IMPULSE ALOFT AS
A POSSIBLE CAUSE...AND THE NAM INDICATES SUBSIDENCE FOR THE REST
OF TONIGHT. SREF CONTINUES TO ILLUSTRATE VERY LITTLE IN THE
PROBABILITY OF MEASURE-ABLE RAINFALL EAST OF THE I-95 CORRIDOR TO
THE CAROLINA COASTS. WILL STICK WITH THE HRRR OUTPUT...AND RAISE
CHANCE POPS ALONG THE IMMEDIATE COAST AFTER 06Z FOR THE SOUTHERN
COASTAL ZONES. WILL THEN FOLLOW THE HRRR AND INDICATE POPS ALONG
THE COAST REACHING THE NC-SC COASTAL BORDER AFTER DAYBREAK SUN.
TONIGHTS WX MAP/FEATURES RESEMBLES WHAT ONE WOULD OBSERVE DURING
THE LATE FALL THROUGH EARLY SPRING MONTHS. IE. SFC HIGH
NOSING/RIDGING FROM THE NE STATES AND A COASTAL TROF/FRONT ALONG
THE IMMEDIATE COAST. DO NOT EXPECT THE COASTAL FRONT/TROF TO MOVE
ONSHORE OVERNIGHT DUE TO THE CORRELATION WITH SFC AND UPPER
TROFFINESS NOT PRESENT ACROSS TX/OK. AS FOR TONIGHT...A NEARLY
SATURATED ATM TO EXIST WITH PWS 2+ INCHES. THE SFC BASED
INSTABILITY HOWEVER... WILL BE LACKING VIA LATEST HRRR RUNS AND
VARIOUS PROGGED NAMBUFR SOUNDINGS ACROSS THE FA. THE LATEST SREF
PROBABILITY OF MEASURE-ABLE PCPN INDICATES THE BEST PROBS WILL
OCCUR FROM ACROSS THE LEE-SIDE OF THE APPALACHIANS TO WEST OF
I-95. WILL CONTINUE TO OUTLINE ALONG OR WEST OF THE I-95 CORRIDOR
FOR PCPN POPS. AS FOR MIN TEMPS...SLIGHTLY TWEAKED THE IMMEDIATE
COASTAL COUNTIES UPWARDS DUE TO THE CLOSE PROXIMITY TO THE 80
DEGREE SSTS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...THE OLD FRONT WILL REMAIN ACROSS THE AREA
THROUGH THE PERIOD. AN UPPER LOW TO THE WEST WILL MAINTAIN SW FLOW
ALOFT SUNDAY BUT HIGH PRESSURE RIDGING IN FROM THE EAST WILL SHIFT
THE BEST LIFT AND DEEP MOISTURE TO THE WEST AND NORTH OF THE FA.
MAIN FOCUS FOR PRECIP SUNDAY WILL BE THE FRONT AND DIURNAL HEATING
SO FORECAST HAS CHANCE POPS FOR THE AFTERNOON AND EVENING HOURS AND
SLIGHT CHANCE IN THE MORNING AND OVERNIGHT SUNDAY INTO MONDAY
MORNING. MAXIMUMS SUNDAY WILL BE WARMER AND SHOULD REACH THE LOW TO
MID 80S UNDER PARTLY TO MOSTLY CLOUDY.
ON MONDAY...THE UPPER LOW TO THE WEST WILL EJECT NORTHEASTWARD AND
BRING UPPER SUPPORT FOR PRECIPITATION TO THE AREA AGAIN WITH THE
FRONT IN THE AREA. THE FORECAST WILL HAVE SLIGHTLY HIGHER CHANCE
POPS FOR MONDAY THAN SUNDAY...AGAIN FOCUSING ON THE PRIME DIURNAL
PERIOD FOR CONVECTION. MAXIMUMS MONDAY SHOULD REACH THE MID TO
UPPER 80S UNDER PARTLY TO MOSTLY CLOUDY SKIES. MINS SUNDAY NIGHT
AND MONDAY NIGHT SHOULD BE WITHIN A COUPLE DEGREES OF 70.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 3 PM SATURDAY...THE 500 MB UPPER LEVEL RIDGE AXIS TRIES TO
BUILD WESTWARD AND WILL ALIGNED ALONG A LINE FROM MOBILE TO
SAVANNAH AND OUR REGION WILL BE ON THE SOUTHERN FRINGES OF THE
NORTHWEST FLOW ON TUESDAY. AS THE WEEK PROGRESSES AN UPPER LEVEL
TROUGH FORMS ALONG THE EAST COAST ON FRIDAY AND WILL DRIVE THE
HIGH PRESSURE RIDGE SOUTHWARD.
AT THE SURFACE THE FRONTAL BOUNDARY WILL REMAIN AND THE MODELS
CONTINUE TO SHOW THIS WEAKNESS IN THE SURFACE PRESSURE PATTERN
THROUGH AT LEAST FRIDAY. PRECIPITABLE WATERS WILL REMAIN HIGH AND
THE ONLY UPPER LEVEL SUPPORT MAY BE FROM SHORTWAVE IN THE NORTHWEST
FLOW. 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 IN THE UPPER 80S TO NEAR 90
EACH DAY AND LOWS IN THE LOWER 70 INLAND AND MID 70S AT THE
BEACHES.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 06Z...EXPECT PREDOMINANTLY IFR CIGS ACROSS THE CWA OVERNIGHT
WITH A COOL MOIST AIR MASS IN PLACE. SOME MVFR/IFR VSBYS ARE ALSO
POSSIBLE AFTER 06Z...ESPECIALLY AT THE INLAND SITES. KFLO HAS THE
BEST CHANCE OF DEVELOPING LIFR CIGS...AS THE STRATUS HAS BEEN MOST
PERSISTENT AT THIS TERMINAL. KFLO/KLBT MAY ALSO SEE -RA IN THE EARLY
MORNING HOURS AS A SHORTWAVE MOVES OVER THE CENTRAL CAROLINAS.
LIFR/IFR CONDITIONS SHOULD IMPROVE TO MVFR THROUGH THE MORNING
HOURS...BECOMING VFR AT ALL TERMS BY MIDDAY. HAVE ADDED VCSH FOR THE
COASTAL TERMS TO ACCOUNT FOR SCATTERED AFTN SHOWERS AS A WEAK
FRONTAL BOUNDARY LINGERS NEAR THE CAROLINA COAST. THE WINDS WILL BE
LIGHT AND VARIABLE FOR MUCH OF THE PERIOD...BECOMING SOUTH-SOUTHEAST
AOB 10 KTS IN THE AFTN AT KILM/KCRE/KMYR.
EXTENDED OUTLOOK...ISOLATED TO SCATTERED AFTN SHOWERS AND T-STORMS
ARE POSSIBLE THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1:30 AM SUNDAY...NO CHANGES TO THE FORECAST WITH THE LATEST
UPDATE. PREVIOUS DISCUSSION FOLLOWS:
SFC PRESSURE PATTERN AND GRADIENT SOMEWHAT DIFFUSE AND LOOSE
ACROSS THE ATLANTIC WATERS. THE COASTAL FRONTS LOCATION ALONG THE
IMMEDIATE COAST HAS MADE WIND DIRECTIONS RATHER TRICKY. THE SFC PG
WILL REMAIN RATHER LOOSE. AS A RESULT...WIND SPEEDS OVERNIGHT WILL
BE AROUND 10 KT. AS FOR THE DIRECTION...WILL TRY TO FIND A
DOMINATE DIRECTION IN LIEU OF GOING VARIABLE IN DIRECTION.
SIGNIFICANT SEAS WILL PRIMARILY BE A RESULT OF WIND DRIVEN WAVES
RUNNING AT 3 TO 5 SECOND PERIODS...WITH HEIGHTS OF 2 TO 3 FT.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...A WEAK GRADIENT WILL REMAIN OVER THE FORECAST
AREA THROUGH THE PERIOD WITH THE DECAYING FRONT NEARBY. WINDS MAY
WELL BE DRIVEN MORE BY MESOSCALE PROCESSES THAN THE ACTUAL GRADIENT.
THIS MAY MEAN E TO SE WINDS BY DAY AND W TO NW WINDS OVER NIGHT DUE
TO LAND AND SEA BREEZE EFFECTS AND THE SHIFTING POSITION OF THE OLD
FRONT. SPEEDS WILL BE 10 KT OR LESS THROUGH THE PERIOD. SEAS INVOF
2 FT ARE EXPECTED THROUGH THE PERIOD.
LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 3 PM SATURDAY...THE WEAKNESS FROM THE FRONTAL BOUNDARY ALONG
THE COAST APPEARS TO CONTINUE THROUGH THE PERIOD. WITH THIS WEAK
PRESSURE GRADIENT THE WINDS TO BE LESS THAN 10 KNOTS AND VARIABLE.
THE LOCAL WAVE MODEL COUPLED WITH THE WAVEWATCH III MODEL IS SHOWING
SEAS AROUND 2 FEET THROUGH THE ENTIRE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DCH
NEAR TERM...DCH/REK
SHORT TERM...RAN
LONG TERM...DRH
AVIATION...BJR
MARINE...DCH/REK/DRH/RAN
AREA FORECAST DISCUSSION
NWS BISMARCK ND
320 AM CDT SUN AUG 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN CONCERN IN THE NEAR TERM WILL BE THE CHANCES OF
THUNDERSTORMS...INCLUDING THE POSSIBILITY OF SEVERE WEATHER.
EARLY MORNING WATER VAPOR IMAGERY SHOWED A WAVE MOVING ACROSS
SOUTHERN PARTS OF SASKATCHEWAN / MANITOBA...WITH ANOTHER WAVE IN
NORTHWEST MONTANA. CONVECTION WITH THE CANADIAN WAVE HAS BEEN
SPARSE...AND THE LATEST NAM / RAP KEEPS THE FORECAST AREA DRY
EARLY THIS MORNING AS THE WAVE PASSES. THE BIGGER CONCERN WILL BE
THE MONTANA WAVE AS IT INTERACTS WITH A WEAK BOUNDARY MOVING
THROUGH THE REGION. A FEW SHOWERS / THUNDERSTORMS ARE POSSIBLE IN
WESTERN NORTH DAKOTA LATER SUNDAY MORNING AS THE WAVE
APPROACHES...BUT DO NOT EXPECT THOSE TO BE SEVERE.
THE SEVERE THREAT IS EXPECTED TO INCREASE THIS AFTERNOON AND
EVENING AS THE MONTANA WAVE HELPS INITIATE THUNDERSTORMS ALONG THE
SLOW MOVING BOUNDARY. THAT BEING SAID...THE CAP REMAINS A
POTENTIAL LIMITING FACTOR DUE TO WARM H7 TEMPERATURES. THE NAM
AND GFS DISAGREE IN REGARDS TO HOW FAST THE MID LEVELS COOL
TODAY...WITH THE NAM BEING MORE AGGRESSIVE. THE NAM WAS ALSO
QUICKER TO INITIATE CONVECTION ALONG THE BOUNDARY ON
SATURDAY...AND AFTER SEEING THE LACK OF DEVELOPMENT ACROSS NORTH
DAKOTA...CONFIDENCE IN HOW WIDESPREAD THE CONVECTIVE DEVELOPMENT
WILL BE IS NOT HIGH. WILL CARRY CHANCE POPS NEAR THE BOUNDARY
TOWARDS LATE AFTERNOON / EARLY EVENING...AND LET LATER SHIFTS
MONITOR TRENDS WITH THE CAP AND POTENTIAL DEVELOPMENT.
IN REGARDS TO THE SEVERE WEATHER THREAT...EXPECT THE MAIN THREAT
AREA TO BE FROM THE SOUTH CENTRAL PART OF THE STATE AND TOWARDS
THE JAMES RIVER VALLEY. THE PRIMARY HAZARD SHOULD BE DAMAGING
WINDS WITH INVERTED V SOUNDINGS...WHILE WARM MID LEVEL
TEMPERATURES COULD LIMIT THE HAIL THREAT TO SOME DEGREE. ELEVATED
LIFTED CONDENSATION LEVELS SHOULD ALSO LIMIT THE TORNADO
POTENTIAL. THE THUNDERSTORM CHANCES ARE EXPECTED TO DIMINISH FROM
WEST TO EAST AS THE WAVE PASSES...WITH DRY WEATHER EXPECTED AGAIN
BY LATE TONIGHT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN HIGHLIGHTS IN THE EXTENDED WILL BE HOT TEMPERATURES
MONDAY AND TUESDAY...WELL INTO 90S...WITH NEAR RECORD HIGHS FOR
BISMARCK TUESDAY. THIS MAY LEAD TO A POSSIBLE HEAT ADVISORY
TUESDAY AFTERNOON ACROSS PORTIONS OF SOUTH CENTRAL NORTH DAKOTA. A
STRONG COLD FRONT WILL FOLLOW FOR TUESDAY NIGHT SUPPRESSING HIGHS
BACK INTO THE 80S FOR THE REST OF THE WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE PATTERN BECOMES MORE ACTIVE
WITH PERIODIC SHOWERS AND THUNDERSTORMS AS A PACIFIC LOW/TROUGH
EJECTS SEVERAL SHORTWAVES VIA A PERSISTENT FETCH OF SOUTHWEST FLOW
ALOFT STRAIGHT INTO NORTH DAKOTA.
FOR MONDAY AND TUESDAY...BEHIND A DEPARTING SHORTWAVE MONDAY MORNING
WILL BE BROAD RIDGING TAKING CONTROL. A LACK OF SHORTWAVE ACTIVITY
MONDAY WITH H85 TEMPS CLIMBING TO AROUND +26C TO +28C...BOTH MONDAY
AND TUESDAY...WILL MAKE THESE THE TWO HOTTEST DAYS IN THE EXTENDED.
PERHAPS A BIT WARMER TUESDAY. LOOKING AT RECORD HIGHS AT THE MAJOR
CITIES MONDAY AND TUESDAY...IT WOULD APPEAR THAT ONLY BISMARCK
WOULD COME CLOSEST TO POSSIBLY TYING A RECORD TUESDAY. THE RECORD IS
100 DEGREES SET BACK IN 1976. WE WILL BE CLOSE TO THAT WITH 98F AS A
FORECAST HIGH TEMPERATURE. WITH MANY SCHOOLS STARTING THIS
WEEK...HAVE TO REALLY CONSIDER THE HEAT IN THE AFTERNOON AS THE HEAT
INDICES WILL BE VERY CLOSE TO 100 DEGREES. WILL HIGHLIGHT THIS IN THE
HAZARDOUS WEATHER OUTLOOK FOR NOW AND BRIEF THE ONCOMING SHIFT THAT
AN ADVISORY MAY BECOME NECESSARY. GFS SOUNDINGS SHOW THAT ENOUGH OF
A CAP REMAINS IN PLACE THROUGH 00Z WEDNESDAY TO INHIBIT CONVECTION.
HAVE DISCOUNTED THE NAM SOLUTION WHICH GENERATES PRECIPITATION EARLY
IN THE DAY...WHILE THE OTHER MODELS KEEP IT DRY DURING THE DAYLIGHT
HOURS.
TUESDAY NIGHT/WEDNESDAY MORNING...A STRONG COLD FRONT WILL PUSH FROM
NORTHWEST TO SOUTHEAST. EXPECT A CHANCE FOR SHOWERS/THUNDERSTORMS
WITH THIS FRONT. H85 TEMPERATURES TAKE A DIGGER WITH +17C IN THE
NORTH WEDNESDAY AFTERNOON TO +20 IN THE SOUTHWEST. SHOULD BE
REFRESHING WITH HIGHS AROUND 80F NORTH TO MID 80S SOUTHWEST. THE
THREAT FOR AN ISOLATED SHOWER/THUNDERSTORM WILL LINGER IN THE SOUTH
THROUGH THE DAY WEDNESDAY.
THURSDAY THROUGH SUNDAY...SOUTHWEST FLOW ALOFT OPENS THE WAY FOR
SEVERAL SHORTWAVE TROUGHS TO MIGRATE THROUGH. UPPER RIDGE WILL BE
DOMINATE IN THE CENTRAL CONUS. THE TIMING OF THE AFOREMENTIONED
SHORTWAVES WILL CHANGE BETWEEN NOW AND LATER IN THE WEEK...BUT THE
HIGHER END CHANCES FOR SHOWERS/THUNDERSTORMS BEGIN TO INCREASE
THURSDAY AND CONTINUE INTO THE WEEKEND. THE ALLBLEND CAPTURES THIS
TREND WELL AND WILL MAINTAIN THAT. THE ECMWF IS A BIT MORE
AGGRESSIVE WITH THE SUCCESSIVE WAVES AND LARGER PRECIPITATION AREAS
VERSUS THE GFS...BUT THE OVERALL PATTERN IN BOTH MODELS IS SIMILAR.
HIGHS WILL REMAIN IN THE 80S WITH LOWS IN THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 320 AM CDT SUN AUG 18 2013
STRATUS DEVELOPMENT WILL HAVE TO BE MONITORED AGAIN EARLY THIS
MORNING...BUT THE STRATUS IS MUCH FARTHER SOUTH THAN YESTERDAY AT
THIS TIME. THE NAM STILL INCREASES H925 RELATIVE HUMIDITY ACROSS
SOUTH CENTRAL NORTH DAKOTA INTO THE JAMES RIVER VALLEY...AND WILL
HINT AT POSSIBLE STRATUS WITH SCATTED CLOUDS AROUND 1500 FT AT
KJMS.
THE NEXT CONCERN WILL BE THE CHANCE OF THUNDERSTORMS AS A FRONTAL
BOUNDARY MOVES ACROSS THE REGION. CONFIDENCE IN TIMING / PLACEMENT
OF THE CONVECTION IS STILL NOT HIGH...AND WILL CARRY VCTS AT THE
TERMINALS TO SUGGEST THUNDERSTORMS ARE POSSIBLE. OVERALL...WILL
STAY WITH VFR FORECASTS AND MONITOR TRENDS EARLY THIS MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1240 AM CDT SUN AUG 18 2013
.UPDATE...
ISSUED AT 1239 AM CDT SUN AUG 18 2013
EARLY MORNING REGIONAL RADAR MOSAIC SHOWS A FEW SHOWERS / ISOLATED
THUNDERSTORMS MOVING ACROSS SOUTHERN MANITOBA...WITH ANOTHER SMALL
CLUSTER IN CENTRAL MONTANA. THE HRRR STILL SUGGESTS THE WAVE
RESPONSIBLE FOR THE ACTIVITY IN SOUTHERN MANITOBA MAY BE ABLE TO
GENERATE AN ISOLATED THUNDERSTORM IN FAR NORTH CENTRAL NORTH
DAKOTA EARLY THIS MORNING. THE WAVE RESPONSIBLE FOR THE CONVECTION
IN CENTRAL MONTANA WILL NOT ARRIVE UNTIL AFTER 12Z SUNDAY...SO
WILL KEEP THE WEST DRY OVERNIGHT...WITH THE CHANCES INCREASING BY
SUNDAY AFTERNOON.
UPDATE ISSUED AT 939 PM CDT SAT AUG 17 2013
THE SURFACE TROUGH HAS INCHED EASTWARD...EXTENDING FROM A LOW IN
MANITOBA TO NEAR TIOGA/STANLEY TO NEAR DICKINSON. 00Z SOUNDINGS
INDICATED STRONG CAP IN PLACE AT GLASGOW/BISMARCK/INTERNATIONAL
FALLS AND POINTS SOUTH. STILL MONITORING RADAR AND SATELLITE FOR
ANY EVIDENCE OF CONVECTION...SINCE AFTER SUNSET THE CAP MAY WEAKEN
- ESPECIALLY WITH THE APPROACH/ARRIVAL OF AN UPPER LEVEL
SHORTWAVE.
LOOKING AT WATER VAPOR SAT LOOP...ONE SHORTWAVE IMPULSE IS OVER
SOUTHEASTERN SASKATCHEWAN - POISED TO CATCH UP TO THE SURFACE
TROUGH. SEEING EVIDENCE OF MID CLOUDS IN THE RADAR LOOPS AND SAT
PICS OVER SOUTHEASTERN SASKATCHEWAN TO SOUTHWESTERN MANITOBA. WILL KEEP
MONITORING FOR ANY DEVELOPMENT...AND HENCE HAVE KEPT SLIGHT
CHANCES IN THE NORTH CENTRAL FOR TONIGHT.
A SECOND SHORTWAVE SEEN IN THE WATER VAPOR LOOP WAS APPROACHING
NORTH CENTRAL MONTANA...AND THIS FEATURE IS PROGGED TO MOVE
EASTWARD SLOWLY OVERNIGHT AND ITS LEADING EDGE IS PROGGED TO REACH
NORTHWESTERN NORTH DAKOTA BY DAYBREAK SUNDAY...FOLLOWED BY A
LARGER IMPULSE LATE MORNING/AFTERNOON IN WESTERN NORTH DAKOTA.
MADE MINOR CHANGES TO TEMPERATURES AND WINDS TO REFLECT CURRENT
TRENDS...BUT NO CHANGES IN LOW TEMPERATURES TONIGHT.
UPDATE ISSUED AT 635 PM CDT SAT AUG 17 2013
THE SURFACE TROUGH EXTENDED FROM A LOW IN NORTHERN MANITOBA TO NEAR
TIOGA/WILLISTON TO NEAR BOWMAN. MID-LEVEL CAP IN PLACE WITH H700
THERMAL RIDGE EXTENDING FROM NEAR HETTINGER TO DEVILS LAKE. AT UPPER
LEVELS...A SHORTWAVE WAS MOVING EASTWARD ACROSS SOUTHEASTERN
SASKATCHEWAN INTO SOUTHERN MANITOBA...AND AGITATED CUMULUS/TOWERING
CUMULUS SEEN IN THE VISIBLE SATELLITE PICS HAD BECOME
THUNDERSTORMS ACROSS SOUTHEASTERN SASKATCHEWAN/SOUTHWESTERN
MANITOBA AROUND 5 PM CDT...BUT HAVE SINCE DIMINISHED. BEST 0-6KM
SHEAR IS ACROSS THIS AREA OF SOUTH CENTRAL CANADA. SUSPECT HIGH-
BASED STORMS...AND BEST DOWNDRAFT CAPE AXIS EXTENDS FROM SOUTHERN
MANITOBA TO THE SURFACE TROUGH AREA OF WESTERN NORTH DAKOTA. TIME
WILL TELL LATER THIS EVENING WHETHER THERE IS ENOUGH ENERGY IN THE
UPPER LEVEL SHORTWAVE TO BREAK THE MID-LEVEL CAP IN PLACE - WITH
THE WEAKEST PART OF THE MID-LEVEL CAP ACROSS NORTHERN NORTH
DAKOTA. THUS THE NORTH CENTRAL (BOTTINEAU/MINOT/KENMARE AREAS)
APPEAR TO HAVE THE BEST SHOT AT SEEING CONVECTION IN NORTH DAKOTA.
OTHER THAN THE MINOT AREA...THE NEXT AREA TO WATCH IS ALONG THE
SURFACE TROUGH WHERE LOW LEVEL CONVERGENCE MAY BE ABLE TO LINK
WITH PLENTY OF CAPE ABOVE THE MID-LEVEL CAP AROUND/AFTER SUNSET.
THE ONGOING FORECAST HAD SLIGHT CHANCES IN THE NORTH CENTRAL THIS
EVENING AND SAW NO REASON TO CHANGE THAT AT THIS TIME.
&&
.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 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1239 AM CDT SUN AUG 18 2013
STRATUS DEVELOPMENT WILL HAVE TO BE MONITORED AGAIN EARLY THIS
MORNING...BUT THE STRATUS IS MUCH FARTHER SOUTH THAN YESTERDAY AT
THIS TIME. THE NAM STILL INCREASES H925 RELATIVE HUMIDITY ACROSS
SOUTH CENTRAL NORTH DAKOTA INTO THE JAMES RIVER VALLEY...AND WILL
HINT AT POSSIBLE STRATUS WITH SCATTED CLOUDS AROUND 1500 FT AT
KJMS.
THE NEXT CONCERN WILL BE THE CHANCE OF THUNDERSTORMS AS A FRONTAL
BOUNDARY MOVES ACROSS THE REGION. CONFIDENCE IN TIMING / PLACEMENT
OF THE CONVECTION IS STILL NOT HIGH...AND WILL CARRY VCTS AT THE
TERMINALS TO SUGGEST THUNDERSTORMS ARE POSSIBLE. OVERALL...WILL
STAY WITH VFR FORECASTS AND MONITOR TRENDS EARLY THIS MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CK
SHORT TERM...TM
LONG TERM...LTH
AVIATION...CK
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
154 AM EDT SUN AUG 18 2013
.SYNOPSIS...
HIGH PRESSURE OVER NEW ENGLAND WILL REMAIN IN CONTROL OF THE WEATHER
INTO THURSDAY. A WEAK UPPER LEVEL DISTURBANCE WILL PASS TO THE
SOUTHEAST SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
THE HRRR MODEL CAME AROUND AND AGREES WITH THE CURRENT SITUATION
WHERE HIGH CLOUDS CONTINUE TO RACE NORTH INTO THE EASTERN HALF OF
THE FORECAST AREA THIS EVENING. THIS IS IN RESPONSE TO MOISTURE
PLUME RACING NORTH OUT OF THE GULF OF MEXICO AT THIS TIME. UPDATED
GRIDS AND ZONE FORECAST TO REFLECT CLOUD COVER CHANGES IN THE
EASTERN HALF OF THE AREA. EXPECTING SKIES TO REMAIN MOSTLY CLEAR
IN THE WEST HALF OVERNIGHT. SHOULD SEE SOME RETREATING OF CLOUD
COVER TO THE EAST AFTER MIDNIGHT TONIGHT.
NOT EXPECTING TO MAKE ANY MAJOR CHANGES TO THE REST OF THE FIELDS
WITH THIS UPDATE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/...
THE AIR MASS WILL CONTINUE TO WARM A LITTLE MORE EACH DAY SO HIGHS
SUN MOSTLY FROM THE UPPER 70S EAST TO LOWER 80S WEST WILL WARM TO
LOW TO MID 80S FAR EAST TO MID TO UPPER 80S WEST BY WED.
THE WEAK UPPER LEVEL TROF OVER THE LOWER OH RIVER VALLEY SUN WILL
LIFT NE INTO THE CWA BY EARLY MON WHILE WEAKENING THEN SHIFT EAST
THRU TUE. THE MODELS DIFFER ON HOW FAR NW THE DEEPER MOISTURE AND
RAIN THREAT WILL BE PULLED. THINK BEST MOVE MAY BE TO TRY AND
MAINTAIN CONTINUITY AND KEEP MAINLY A SLIGHT CHANCE FOR THE SE SUN
EVE THRU MON.
THE MODELS INDICATE ANOTHER WEAK UPPER TROF DROPPING SE INTO THE
AREA TUE WITH MAYBE SOME ISOLATED CONVECTIVE DEVELOPMENT. ANOTHER
WEAK TROF PROGGED TO BE APPROACHING LERI BY END OF WED NIGHT BUT
SURFACE FRONT STILL LOOKS TO BE FAR ENOUGH TO THE NW TO ALLOW WED
NIGHT TO SAY DRY.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
A WARMER AND MORE HUMID AIR MASS IS EXPECTED WEDNESDAY INTO THURSDAY
AS HIGH PRESSURE PERSISTS OVER THE SOUTHEASTERN US. THERE IS A PIECE
OF JET ENERGY MOVING ACROSS ONTARIO ON THURSDAY THAT WILL PUSH A
WEAK COLD FRONT TOWARD NORTHERN OHIO AND NW PA. THERE MAY BE JUST
ENOUGH CONVERGENCE ALONG A LAKE INDUCED BOUNDARY TO ALLOW FOR A
MENTION OF LATE AFTERNOON AND EVENING THUNDERSTORMS. MODELS THEN
STRUGGLE ON WHAT TO DO FRIDAY INTO SATURDAY. IF THE ECMWF IS CORRECT
WE WILL REMAIN WARM AND HUMID AS THE WEAK FRONTAL BOUNDARY FROM
THURSDAY EVENING LIFTS NORTH AS A WARM FRONT INTO FRIDAY NIGHT.
HAVE LEANED TOWARD THE WARMER ECMWF SOLUTION IN THE EXTENDED WITH
HIGHS WELL INTO THE 80S.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
GENERALLY VFR CONDITIONS WILL PERSIST OVERNIGHT AND THROUGH
SUNDAY ALTHOUGH COULD SEE PATCHY EARLY MORNING FOG/MIST RESULTING
IN MVFR VISIBILITIES AROUND SUNRISE. DECENT MOISTURE AROUND 5K
FEET WORKS IN FROM THE SOUTH. HAVE CONTINUED THE BKN DECK FOR
LATER TODAY. CAK/YNG MAY EVEN SEE SOME LIGHT RAIN AFTER 03Z MON
BUT NOT IN TAF JUST YET.
OUTLOOK...NON-VFR POSSIBLE IN EARLY MORNING FOG MONDAY THROUGH
THURSDAY.
&&
.MARINE...
HIGH PRESSURE WILL GENERALLY REMAIN TO THE EAST AND SOUTHEAST OF
LAKE ERIE THROUGH TUESDAY. THIS WILL ALLOW ONSHORE FLOW TO DEVELOP
EACH AFTERNOON. OTHERWISE WE WILL WATCH THE HIGH SLOWLY WEAKEN AND
DRIFT FURTHER SOUTH ALLOWING EASTERLY WINDS TO SHIFT TO A SOUTH AND
SOUTHWEST DIRECTION. THIS WIND SHIFT WILL BE IN RESPONSE TO
DEEPENING LOW PRESSURE OVER NORTHERN ONTARIO. WHILE WINDS WONT BE
ALL THAT STRONG THEY WILL INCREASE TO 10 TO 15 KNOTS FROM THE
SOUTHWEST ON WEDNESDAY INTO THURSDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ADAMS
NEAR TERM...LOMBARDY
SHORT TERM...ADAMS
LONG TERM...MULLEN
AVIATION...OUDEMAN
MARINE...MULLEN
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
158 AM EDT SUN AUG 18 2013
.SYNOPSIS...
A WEDGE OF COOL HIGH PRESSURE WILL REMAIN IN PLACE OVER THE
CAROLINAS THROUGH THE WEEKEND...THEN GRADUALLY WEAKEN EARLY NEXT
WEEK. MEANWHILE A SERIES OF LOWS WILL RIDE UP ALONG A STATIONARY
FRONTAL BOUNDARY LOCATED ALONG THE CAROLINA COAST BRINGING MOIST
TROPICAL AIR INTO THE SOUTHEAST. THIS WILL GENERATE WIDESPREAD
SHOWERS ACROSS THE AREA THROUGH THE FIRST PART OF THE WEEK. DRIER
AND WARMER WEATHER IS EXPECTED TO RETURN BY THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 1045 PM EDT SATURDAY...SEVERAL BANDS OF SCATTERED SHOWERS
CONTINUE TO PUSH NORTHWARD ACROSS THE REGION WITH THE HEAVIEST RAIN
CURRENTLY FALLING ACROSS THE NORTH CAROLINA PIEDMONT. AS FOR SKY
COVER...MOST LOCATIONS ARE SEEING LOW STRATUS AS THE MOIST BOUNDARY
LAYER SETTLES...WHILE OTHER LOCATIONS ARE SEEING A MIXTURE OF
LOW/MID LEVEL STRATUS. LATEST NAM AND HRRR GUIDANCE LINE UP
WELL WITH THE POP TREND IN THE FORECAST. HOWEVER...DID MAKE A FEW
CHANGES TO THE NEAR TERM POP GRIDS TO ACCOUNT FOR HEAVIER SHOWERS
ACROSS THE NC PIEDMONT AND FURTHER SOUTH INTO THE NORTHEAST GA
MOUNTAINS. OTHERWISE...DID NOT MAKE ANY SIGNIFICANT CHANGES OTHER
THAN ADJUSTING TEMPERATURE AND DEWPOINT TRENDS TO REFLECT LATEST
OBSERVATIONS.
PREVIOUS DISCUSSION...
AS OF 245 PM...CWFA REMAINS IN THE DEEP SLY FLOW BETWEEN UPPER LOW
NEAR THE JUNCTION OF THE OH AND MS RIVERS AND THE BERMUDA ANTI-
CYCLONE. A SERIES OF WAVES WILL MOVE THRU THIS FLOW ALONG WITH A
SERIES OF JET STREAKS PROVIDING SYNOPTIC SCALE LIFT AND UPPER
DIVERGENCE. THIS FLOW ALSO KEEPS A PLUME OF TROPICAL MOISTURE OVER
THE CWFA. PW VALUES ARE NEAR 2 INCHES WHICH IS HIGH...BUT NOT
EXCESSIVELY SO. ISENTROPIC LIFT WILL CONTINUE TO INCREASE ACROSS THE
AREA INTO THE EARLY EVENING BRINGING WIDESPREAD RAINFALL BACK ACROSS
THE AREA. WITH THE FORCING AND PW VALUES...EXPECT MODERATE RAINFALL
AMOUNTS FOR BASIN AVERAGES. CANNOT RULE OUT SOME HEAVY RAINFALL
ADDING UP AFTER A SERIES OF MODERATE RAIN LEADING TO SOME HIGH WATER
LEVELS. HOWEVER...THE THREAT OF ANY WIDESPREAD HEAVY RAINFALL AND/OR
FLOODING IS QUITE LOW. THE BEST ISENTROPIC LIFT MOVES OFF THE THE
NORTH OVERNIGHT AS LOW LEVEL FLOW BECOMES MORE SWLY...AND BEST
FORCING RETREATS TO THE WEST. HOWEVER...LOW LEVEL MOISTURE REMAINS
QUITE HIGH. THEREFORE... EXPECT WIDESPREAD RAINFALL TO DIMINISH WITH
BEST CHC LINGERING OVER THE MTNS. AREAS OF FOG SHUD DEVELOP TOWARD
MORNING AND COULD BECOME DENSE IN AREAS...ESPECIALLY IF WEDGE BEGINS
TO ERODE. LOWS WILL BE A FEW DEGREES BELOW NORMAL.
SUNDAY...UPPER LOW BEGINS TO OPEN UP AND MOVE NORTHEAST THRU THE OH
VALLEY AS THE RIDGING BEGINS TO MOVE IN FROM THE EAST. THIS HELPS
TURN THE FLOW MORE SWLY ENDING THE THREAT OF STRONG ISENTROPIC LIFT
OVER THE AREA. THIS MAY ALSO HELP ERODE THE LOW LEVEL CAD INVERSION
ALLOWING A WEAK SWLY SFC FLOW TO DEVELOP. THIS SHOULD ALLOW THE LOW
LEVELS TO DRY SLIGHTLY CREATING A BREAK IN THE LOW CLOUDS AND SOME
HEATING TO DEVELOP. THIS SHUD ALSO LEAD TO WEAK INSTABILITY DURING
THE AFTERNOON. AGAIN...BEST PRECIP CHC WILL BE OVER THE WEST WHERE
MOISTURE AND FORCING ARE HIGHEST AND IMPINGING RIDGE HAS LESS
INFLUENCE. WITHOUT THE CONTINUATION OF NELY WINDS...LOW CLOUDS AND
STEADY PRECIP...TEMPS WILL BE ABLE TO RISE THRU THE DAY. IN FACT...
LOW LEVEL THICKNESSES WILL BE HIGHER. ANY SUNSHINE WOULD ALLOW A
QUICK RISE IN TEMPS. HOWEVER...EXPECT THERE WILL BE ENUF CLOUDS...
EVEN WITH LOW CLOUDS ERODING...TO RETARD SIGNIFICANT HEATING. THAT
SAID...EXPECT HAVE GONE WITH THE BIAS CORRECTED MOS WHICH IS COOLER
BUT STILL ALLOWS TEMPS TO RISE INTO THE 70S ACROSS THE AREA.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
AS OF 245 PM EDT SATURDAY...A CLOSED UPPER LOW OVER THE WEST WILL
OPEN UP AS IT LEFTS NE ACROSS THE OHIO VALLEY SUN NIGHT INTO MONDAY.
A LOW AMPLITUDE UPPER RIDGE OF HIGH WILL BUILD SOUTH OF THE CWA
TUESDAY WITH A SERIES OF UPPER DISTURBANCES RIPPLING THROUGH THE
REGION IN WEAK WESTERLY FLOW ALOFT.
AT THE SURFACE...THE LATEST NAM HAS TRENDED A BIT FASTER WITH THE
EROSION OF THE COOL AIR WEDGE BY SUN NIGHT WHILE THE GFS KEEPS THE
WEDGE AT LEAST THROUGH MIDDAY MONDAY. NONETHELESS...WE WILL SEE
RETURN SOUTHERLY FLOW BY MONDAY AFTERNOON AS THE HIGH SHIFTS
OFFSHORE AND CONTINUES TO RIDGE INTO THE REGION. THE HIGH WILL
REMAIN CENTERED OFFSHORE TUESDAY WITH CONTINUED SE FLOW REGIME OVER
THE CWA. IN RESPONSE TO THE RETURN FLOW...MODEL SOUNDINGS INDICATE
THAT SBCAPE VALUES WILL BE AROUND 700-1500J/KG WITH PW VALUES
REACHING 2 INCHES BOTH MON AND TUE AFTERNOON. IN ADDITION...THE
MAGNITUDE OF THE MBE VELOCITY WILL BE LESS THAN 10 KTS MEANING
STORMS WILL MOVE SLOWLY. SO LOCALIZED FLASH FLOODING CAN NOT BE
RULED OUT. TEMPERATURES WILL WARM UP INTO THE LOWER 80S EAST OF THE
MOUNTAINS BY MONDAY BUT STILL WE ARE LOOKING AT AROUND 3-5 DEGREES
BELOW NORMAL VALUES.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM EDT SATURDAY...THE GLOBAL MODELS AGREE THAT AN UPPER
RIDGE WILL PREVAIL OVER THE SE STATES TUE NIGHT INTO THU BEFORE
BECOMING NORTHERLY FLOW ALOFT BY FRI AS AN UPPER TROUGH OVER THE
SOUTH-CENTRAL CANADA DIGS DOWN INTO THE MID ATLANTIC STATES. THE
UPPER FLOW WILL REMAIN NORTHERLY OVER THE REGION THROUGH THE END OF
THE MEDIUM RANGE PERIOD AS A BROAD UPPER RIDGE OF H5 HIGH REMAINS
ANCHORED OVER THE CENTRAL CONUS.
AT THE SURFACE...MOIST SE FLOW WILL PREVAIL TUE NIGHT INTO FRIDAY AS
THE BERMUDA HIGH PRESSURE CONTINUES TO RIDGE INTO THE CWA. MODEL
SOUNDINGS INDICATE THAT ATMOS WILL BE GENERALLY UNCAPPED WITH SBCAPE
VALUES RANGING FROM 1000 TO 2000J/KG ON EACH AFTERNOON. HENCE I HAVE
MENTIONED DIURNAL 30-40 PERCENT POPS DURING THIS PERIOD. BY FRI
NIGHT...THE LATEST 12Z GFS INDICATES THE BERMUDA HIGH WILL WEAKEN
AND SHIFT EAST OF THE AREA AS ANOTHER HIGH PRESSURE CENTERED OVER
THE GREAT LAKES REGION GRADUALLY RIDGES DOWN INTO THE SE STATES.
MEANWHILE...THE 00Z ECMWF KEEPS THE BERMUDA HIGH OVER THE REGION
THROUGH THE END OF THE MEDIUM RANGE PERIOD. GIVEN THE
UNCERTAINTY..HAVE CARRIED LOWER POPS ON SAT. TEMPERATURES WILL
REMAIN A FEW DEGREES BELOW NORMAL THRU THE PERIOD.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AT KCLT...LGT RAIN AND DRIZZLE EXPECTED THRU DAYBREAK WITH LIFR
CONDITIONS...CIGS APPROACHING MINIMUMS. EXPECTING IFR
VSBY...POSSIBLY LOWERING TO LIFR AS WELL. A WEAK WEDGE IS EXPECTED
TO ERODE DURING THE DAY TODAY...BUT MODELS OFTEN ARE TOO FAST AT
IMPROVING CONDITIONS. A MODEL BLEND DOES RESULT IN SLOWER
IMPROVEMENT TREND...BUT STILL EXPECT VFR CONDITIONS BY EARLY/MID
AFTN. GUIDANCE ALSO IN DECENT AGREEMENT THAT WHILE THE WEDGE
ERODES...THERE WILL NOT BE MUCH INSTBY FOR DEEP CONVECTION THIS FAR
NORTH. STILL EXPECT TO SEE AT LEAST SHRA...SO PROB30 FOR THAT. LIGHT
S/SWLY LLVL FLOW AND LINGERING MOISTURE WILL PROBABLY RESULT IN A
RETURN OF LOWER STRATUS AFTER SUNSET THIS EVENING. WINDS WILL BE
CALM OR LIGHT/VRB. PROBABLY FAVOR A N/NE DIRECTION THRU ABOUT LATE
MORNING...THEN SOME OF THE GUIDANCE HAS WINDS TURN OUT OF THE SOUTH.
EITHER WAY...SHUD BE LESS THAN 5 KTS.
ELSEWHERE...EXPECTING IFR/LIFR CIGS THRU MID MORNING ACRS THE
REGION. HOWEVER...STARTING OUT WITH A FEW POCKETS OF HIGHER CIGS DUE
TO SOME MOD RAIN THAT MIXED OUT SOME OF THE MOISTURE. HAVE TEMPO FOR
THE CHANGEABLE HGTS...BUT THINGS SHUD SETTLE BACK TO IFR.
OTHERWISE...BASICALLY THE SAME CONCERNS AS KCLT IN ABOVE PARAGRAPH.
OUTLOOK...SOME IMPROVEMENT TO MOSTLY VFR EXPECTED EARLY NEXT WEEK.
SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS WILL LIKELY CAUSE
RESTRICTIONS BY MID TO LATE WEEK AS DIURNAL EFFECTS DOMINATE.
CONFIDENCE TABLE...
06-12Z 12-18Z 18-24Z 00-06Z
KCLT HIGH 86% MED 73% HIGH 94% MED 71%
KGSP HIGH 81% HIGH 83% HIGH 93% MED 69%
KAVL MED 79% MED 76% MED 77% MED 72%
KHKY MED 76% HIGH 82% HIGH 96% HIGH 86%
KGMU HIGH 84% HIGH 84% HIGH 82% MED 76%
KAND HIGH 88% MED 76% MED 70% HIGH 86%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PAT
NEAR TERM...CDG/RWH
SHORT TERM...JOH
LONG TERM...JOH
AVIATION...ARK
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
315 AM CDT SUN AUG 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 314 AM CDT SUN AUG 18 2013
WARM AIR ADVECTION REGIME IN FULL SWING THIS MORNING WITH 35+ KT LOW
LEVEL JET ACROSS EASTERN SODAK AND TOP OF UPPER RIDGE NUDGING
OVERHEAD. EARLY MORNING SURFACE ANALYSIS SHOW 6 MB PRESSURE IN
PLACE...TIGHTEST ACROSS SODAK WITH HIGH PRESSURE STILL LOCKED IN
PLACE ACROSS THE SOUTHERN GREAT LAKES/NORTHEAST CONUS. PRESSURE
GRADIENT SHOULD CONTINUE TO TIGHTEN ACROSS THE FORECAST AREA TODAY
IN RESPONSE TO APPROACHING INVERTED SURFACE TROUGH AND UPPER SHORT
WAVE...CURRENTLY OVER SASKATCHEWAN/MONTANA BORDER PER WATER VAPOR
IMAGERY. GOOD MIXING TO AROUND 850MB SHOULD RESULT WITH TEMPERATURES
WARMING TO THE LOW TO UPPER 80S ACROSS THE AREA. THERE IS STILL A
RIBBON OF RESIDUAL MOISTURE IN PLACE THAT WILL ALSO LIKELY RESULT IN
SOME CU DEVELOPMENT THIS AFTERNOON...ESPECIALLY ACROSS SE SODAK.
CONVECTION THAT INITIATES ALONG TRAILING TROUGH ASSOCIATED WITH
APPROACHING SHORT WAVE SHOULD REMAIN NORTHWEST OF THE REGION THIS
EVENING. STRONG THERMAL CAP IN PLACE WILL REALLY LIMIT ANY POTENTIAL
FOR CONVECTION APPROACHING THE FSD CWA...HOWEVER AS WAVE TRAVERSES
THE UPPER RIDGE OVERHEAD LATE EVENING/EARLY MONDAY...THERE IS A
SMALL POSSIBILITY OF ELEVATED ISOLATED STORMS ACCOMPANYING THE
WEAKENING BOUNDARY TOWARD THE HURON AREA. A 30+ KT LLJ ALSO DEVELOPS
WHICH NOSES INTO NE SODAK AND COULD PROVIDE SOME ADDITIONAL LIFT FOR
CONVECTION. AGAIN...MUCH OF THE ACTIVITY SHOULD STAY NORTH OF THE
AREA...WHERE THE STRONGEST CONVERGENCE AND FORCING EXISTS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 314 AM CDT SUN AUG 18 2013
MONDAY INTO TUESDAY LOOKS HOT...DRY WITH ONLY AN AVERAGE SOUTHERLY
WIND. WARM AIR IN THE LOWER AND MID LEVELS BUILDS INTO THE REGION
WITH STEADY TO RISING HEIGHTS ALOFT. THIS SUPPORTS VERY WARM
READINGS...ESPECIALLY ON TUESDAY AS A WEAK BOUNDARY TO THE NORTH MAY
ENHANCE MIXING JUST A BIT IN THE NORTH AND WEST CWA. AIMING FOR 85
TO 90 IN THE EASTERN CWA AND 90 TO 95 IN THE WEST ON MONDAY WITH
MAINLY 90S ON TUESDAY. CENTRAL PARTS OF SOUTH DAKOTA COULD TOUCH THE
CENTURY MARK TUESDAY. WARM MONDAY NIGHT AND TUESDAY NIGHT WITH LOWS
FROM THE UPPER 60S TO AROUND 70.
DURING THE WEDNESDAY THROUGH SATURDAY TIME FRAME...A FAIRLY FLAT
RIDGE WILL BE FOUND ACROSS THE NORTHERN AND CENTRAL PLAINS WITH FAST
MID AND UPPER LEVEL MAINLY WESTERLY FLOW ACROSS SOUTHERN CANADA.
EACH MODEL IS IN FAIRLY GOOD AGREEMENT WITH THIS ASSESSMENT AND
SUSPECT THIS WILL KEEP MOSTLY ABOVE NORMAL TEMPERATURES IN PLACE AND
MAINLY DRY CONDITIONS. AS A JET STREAK PASSES WEDNESDAY NIGHT INTO
THURSDAY THERE WILL BE A SMALL CHANCE FOR THUNDERSTORMS BUT THE
BETTER CHANCES LIKELY OFF TO THE NORTH A BIT. FOR NOW THE ECMWF IS
THE WARMEST WHILE THE GFS AND GEM ARE A LITTLE MORE AGGRESSIVE WITH
THE COOLER AIR THAT LEAKS SOUTH ON WEDNESDAY INTO THURSDAY. WILL
LEAN A LITTLE MORE TOWARDS THE ECMWF OUTPUT AS THE JET STREAK SEEMS
PRETTY FAR NORTH AND THE GEM AND GFS MAY BE OVERDOING THE COOLER AIR
JUST A BIT. THIS MEANS CONTINUED ABOVE NORMAL TEMPERATURES THROUGH
THE ENTIRE PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1040 PM CDT SAT AUG 17 2013
00Z NAM12 AND LATEST RUC13 MODELS ARE CONTINUING TO SHOW THE SAME
TRENDS AS THEIR EARLIER COUNTERPARTS DID. BOTH ARE IN GOOD AGREEMENT
IN BRINGING SOME OF THE STRATUS CURRENTLY IN CENTRAL NEBRASKA
NORTHWARD TONIGHT ALONG THE LOW LEVEL JET. IN OUR FAR WEST...LOWER
END MVFR CEILINGS ARE LIKELY IN GREGORY COUNTY SOUTH DAKOTA. AT
THIS TIME...IT APPEARS THAT THE MAIN PORTION OF THIS STRATUS WILL
STAY TO THE WEST OF KHON DEEPER INTO CENTRAL SOUTH DAKOTA...BUT AM
CONCERNED THAT SOME MVFR FOG WILL DEVELOP IN THE JAMES RIVER VALLEY
AROUND SUNRISE. AS FOR CLOUDS...KEPT THE STRATUS POTENTIAL AT KHON
ONLY IN THE MVFR SCATTERED CATEGORY. FURTHER EAST...BOTH MODELS
ALSO SHOW A STRIPE OF HIGHER BASED STRATUS EXTENDING NORTHEASTWARD
FROM CENTRAL NEB TOWARD THE I 29 CORRIDOR...AS WINDS AROUND 800MB
VEER FROM THE SOUTH TO SOUTHWEST OVERNIGHT. EVIDENCE OF THIS
HAPPENING IS ALREADY OCCURRING WITH O NEILL NEB SHOWING 5000 FOOT
SCATTERED...AND SCATTERED HIGH BASED STRATUS EXTENDING SOUTH OF
THERE. THIS FAR NORTH...THE HIGHER BASED STRATUS SHOULD BE NEAR
4000 FEET AGL AND COULD VERY WELL GO BROKEN AT KFSD BEFORE
SUNRISE...POSSIBLY STAYING SCATTERED AT KSUX.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...08
AVIATION...MJ
FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND MONDAY
ISSUED AT 350 AM CDT SUN AUG 18 2013
THE MAIN FCST CONCERNS ARE TEMPERATURES AND SMALL PCPN CHANCES.
WV IMAGERY AND RUC ANALYSIS INDICATED UPPER LEVEL RIDGING OVER THE
ROCKIES AND NORTHERN PLAINS...WITH STRONG ZONAL FLOW OVER THE
NORTHERN TIER OF THE U.S. AND CANADA. THE MAIN SHORT-WAVE ENERGY
WAS TRACKING THROUGH SOUTHERN SASK AND MANITOBA. THE WSTRN
PERIPHERY OF A LARGE SFC HIGH PRESSURE SYSTEM WAS STILL SITUATED
OVER WI...WITH STRONG RETURN FLOW SETTING UP IN ADVANCE OF A COLD
FRONT MOVG THROUGH THE DAKOTAS.
HIGH PRESSURE WILL ONCE AGAIN DOMINATE OUR WEATHER TODAY...WITH
UPPER LEVEL ENERGY REMAINING WELL TO OUR NORTH. EXPECT DIURNAL
CUMULUS CLOUDS TO DEVELOP AGAIN TODAY...ALONG WITH AN INCREASE IN
HIGH CLOUDS ACROSS N WI. MIXING THROUGH 825-800 MB SHOULD YIELD
MAX TEMPS IN THE LOWER TO MIDDLE 80S.
A S/W TROF IS EXPECTED TO MOVE INTO NW WI LATE TONIGHT. SOME WAA
WILL ALSO OCCUR OVER NW/NC WI...WITH SOME ELEVATED INSTABILITY
WORKING ITS WAY TOWARD OUR NW COUNTIES BY MORNING. GENERAL MODEL
CONCENSUS IS TO KEEP ANY PCPN JUST NW OF GRB CWA THROUGH 12Z...
SO WILL GO WITH A DRY FCST FOR NOW. THINK THAT FOG WILL LESS OF
THREAT THAN IT HAS BEEN FOR THE PAST SEVERAL NIGHTS...AS THE SFC
PRESSURE GRADIENT TIGHTENS UP AND BOUNDARY LAYER FLOW INCREASES TO
15-20 KTS. TEMPS SHOULD BE A FEW DEGREES WARMER...WITH LOWS IN THE
50S.
ON MONDAY...A S/W TROF WILL MOVE THROUGH NORTHERN WI...PERHAPS
TRIGGERING ISOLD TSTMS WITHIN A WEAK INSTABILITY AXIS OVER NC AND
FAR NE WI. INCREASING SW WINDS SHOULD PULL WARMER TEMPS INTO THE
REGION...BOOSTING HIGHS INTO THE MIDDLE TO UPPER 80S AT MOST
LOCATIONS.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
ISSUED AT 350 AM CDT SUN AUG 18 2013
SUMMER TIME PATTERN EXPECTED THROUGH MUCH OF THE WEEK. THE BIG
STORY WILL BE THE HEAT WITH HIGHS WELL INTO THE 80S AND SOME 90S
TUESDAY AND WEDNESDAY. COLD FRONT IS EXPECTED TO ENTER NORTHWEST
WISCONSIN WEDNESDAY AFTERNOON...PASS ACROSS THE AREA WEDNESDAY
NIGHT AND THEN PUSH SOUTH OF THE AREA ON THURSDAY. WITH THE HEAT
AND HUMIDITY IN PLACE ALONG WITH 0-6 KM SHEAR...THERE IS STILL
SOME POTENTIAL FOR STRONG OR SEVERE STORMS ACROSS THE AREA...WHICH
IS ALREADY IN THE HAZARDOUS WEATHER OUTLOOK.
BEYOND WEDNESDAY NIGHT...IT APPEARS THE GFS/CANADIAN ARE TAKING
THE LEAD IN MODEL TRENDS FOR THURSDAY/THURSDAY NIGHT. THIS IS UNUSUAL
SINCE THE ECMWF USUALLY PERFORMS BETTER IN THE OUTER PERIODS. ON THE
00Z RUN TONIGHT...THE GFS/CANADIAN PUSH THE FRONT FAR ENOUGH SOUTH
OF THE AREA TO ALLOW FOR DRY CONDITIONS LATER THURSDAY MORNING
INTO THURSDAY AFTERNOON. HAVE REMOVED POPS ACROSS THE NORTH ON
THURSDAY AND CONTINUED A SMALL CHANCE ACROSS THE SOUTH. FIGURING
THE SMALL CHANCE WOULD BE FOR ANY LINGERING MORNING CONVECTION.
STILL A LOT OF UNCERTAINTY WHEN CONVECTION WOULD RETURN THURSDAY
NIGHT/FRIDAY OR EVEN FRIDAY NIGHT AMONG THE MODELS. WILL LEAVE
FRIDAY/SATURDAY FORECAST ALONE DUE TO LARGE MODEL UNCERTAINTY.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1031 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 EVENTUALLY 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...SO FG THERE WL BE MORE PATCHY THAN LAST NGT.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....KIECKBUSCH
LONG TERM......ECKBERG
AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1100 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 06Z TAFS THROUGH 06Z SUNDAY EVENING)
ISSUED AT 1057 PM MDT SAT AUG 17 2013
FOG EXPECTED TO AGAIN DEVELOP OVER PORTIONS OF THE NEBRASKA
PANHANDLE AFTER MIDNIGHT TONIGHT AND LAST THROUGH MID SUNDAY
MORNING BEFORE COMPLETELY DISSIPATING. LIFR CONDITIONS AT TIMES
WITH THE FOG. ISOLATED THUNDERSTORMS EXPECTED SUNDAY AFTERNOON
WITH ERRATIC GUSTY WINDS NEAR THUNDERSTORM ACTIVITY.
&&
.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...LIEBL
FIRE WEATHER...RJM
AREA FORECAST DISCUSSION...CORRECTED
NWS COLUMBIA SC
1142 AM EDT SUN AUG 18 2013
.SYNOPSIS...
THE LOW LEVEL WEDGE OVER OUR REGION WILL SLOWLY WEAKEN
TODAY...PROVIDING A CHANCE OF LATE DAY SHOWERS AND THUNDERSTORMS
OVER PORTIONS OF THE REGION. SEASONAL TEMPERATURES...ALONG WITH A
CHANCE OF MAINLY AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS...ARE EXPECT THIS WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST SATELLITE IMAGES AND SURFACE OBS REVEAL WEDGE BEGINNING TO
BREAK ACROSS SOUTHERN PORTIONS OF THE CSRA AND SW MIDLANDS...WITH
DECREASING CLOUDINESS ACROSS THAT REGION AND SOUTH ACROSS SE GA.
DIURNAL HEATING WILL LEAD TO INCREASING INSTABILITIES ACROSS SE
GA AND NEAR OUR S/SW FA. LATEST HRRR AND NARRE SUGGESTS CONVECTION
DEVELOPING DURING THE MID AFTN ACROSS SE GA...DRIFING NORTH INTO
THE CSRA AND PORTIONS OF THE MIDLANDS LATE THIS AFTN AND EVE.
STILL SOME UNCERTAINTIES AND MODEL DIFFERENCES WITH REGARDS TO
TIMING/LOCATION/COVERAGE OF PRECIP TODAY. WILL MAINTAIN BEST POPS
CSRA. WEDGE COULD POSSIBLY SHIFT BACK TO THE SOUTH SOME TONIGHT.
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
THE WEDGE IS EXPECTED TO WEAKEN OVER THE MIDLANDS AND CSRA BY
MONDAY. A DEEP MOIST SOUTHERLY FLOW WILL BE ACROSS THE AREA WITH
WEAK MOISTURE FLUX. PRECIPITABLE WATER REMAINS AT OR ABOVE 2
INCHES. THE AIR MASS IS FORECAST TO BECOME MODERATELY UNSTABLE.
SO...WITH DIURNAL HEATING...EXPECT AT LEAST SCATTERED CONVECTION.
WE COULD ALSO SEE CONVECTION DEVELOP ALONG THE SEA-BREEZE FRONT.
WENT WITH HIGH CHANCE POPS FOR MONDAY WITH HIGHS IN THE MID TO
UPPER 80S AND LOWS AROUND 70.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
WEAK UPPER TROUGHINESS TO OUR N AND NW...WHILE UPPER HIGH BUILDS
WESTWARD FROM THE ATLANTIC REMAINING CENTERED JUST TO OUR S AND SE.
SURFACE FRONT EXPECTED TO CONTINUE SLOWLY LIFTING NORTH OR
WEAKENING. IT APPEARS SUFFICIENT ATMOSPHERIC MOISTURE AND
INSTABILITY WILL REMAIN. MODEL CONSENSUS POPS ARE TRENDING
DOWN...THOUGH STILL ABOVE CL IMO AT LEAST THROUGH MIDWEEK...AND
WILL EXPECT POPS TO BECOME MORE DIURNALLY FAVORED WITH DAYTIME
HEATING. TEMPS SHOULD BEGIN TRENDING UP MORE TOWARDS CL IMO.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
CIGS ARE SLOWLY IMPROVING AND ARE MOSTLY MVFR AT THE TERMINALS AT
15Z. WILL EXPECT CONTINUED GRADUAL IMPROVEMENT IN CIGS WITH
DIURNAL HEATING AND WITH WEDGE SLOWLY ERODING/LIFTING NORTH.
LATEST HIGH RES MODELS INDICATING CONVECTION DEVELOPING ACROSS SE
GA BY MID AFTN...DRIFTING NORTH INTO OUR FA BY LATE AFTN/EVE. FOR
NOW...WILL HANDLE WITH VCSH AT AGS/DNL/OGB. WILL AMEND LATER FOR
STRONGER MENTION IF/WHEN CONFIDENCE WARRANTS. CIGS COULD LOWER
AGAIN TONIGHT AS WEDGE TRIES TO BUILD BACK TO THE
SOUTH...ESPECIALLY AT THE MORE NORTHERN TERMINALS CAE/CUB. WILL
ADDRESS THAT IN LATER TAF ISSUANCES.
EXTENDED AVIATION OUTLOOK...LATE NIGHT/EARLY MORNING
FOG/STRATUS. CHANCE OF AFTERNOON/EVENING THUNDERSTORMS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1132 AM EDT SUN AUG 18 2013
.SYNOPSIS...
THE WEDGE PATTERN WILL LINGER OVER OUR AREA TODAY THEN WEAKEN
MONDAY. SEASONABLE TEMPERATURES WILL RETURN BY MIDWEEK AS HIGH
PRESSURE OVER THE WESTERN ATLANTIC RIDGES INTO THE SOUTHEASTERN
STATES.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST SATELLITE IMAGES AND SURFACE OBS REVEAL WEDGE BEGINNING TO
BREAK ACROSS SOUTHERN PORTIONS OF THE CSRA AND SW MIDLANDS...WITH
DECREASING CLOUDINESS ACROSS THAT REGION AND SOUTH ACROSS SE GA.
DIURNAL HEATING WILL LEAD TO INCREASING INSTABILITIES ACROSS SE
GA AND NEAR OUR S/SW FA. LATEST HRRR AND NARRE SUGGESTS CONVECTION
DEVELOPING DURING THE MID AFTN ACROSS SE GA...DRIFING NORTH INTO
THE CSRA AND PORTIONS OF THE MIDLANDS LATE THIS AFTN AND EVE.
STILL SOME UNCERTAINTIES AND MODEL DIFFERENCES WITH REGARDS TO
TIMING/LOCATION/COVERAGE OF PRECIP TODAY. WILL MAINTAIN BEST POPS
CSRA. WEDGE COULD POSSIBLY SHIFT BACK TO THE SOUTH SOME TONIGHT.
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
THE WEDGE IS EXPECTED TO WEAKEN OVER THE MIDLANDS AND CSRA BY
MONDAY. A DEEP MOIST SOUTHERLY FLOW WILL BE ACROSS THE AREA WITH
WEAK MOISTURE FLUX. PRECIPITABLE WATER REMAINS AT OR ABOVE 2
INCHES. THE AIR MASS IS FORECAST TO BECOME MODERATELY UNSTABLE.
SO...WITH DIURNAL HEATING...EXPECT AT LEAST SCATTERED CONVECTION.
WE COULD ALSO SEE CONVECTION DEVELOP ALONG THE SEA-BREEZE FRONT.
WENT WITH HIGH CHANCE POPS FOR MONDAY WITH HIGHS IN THE MID TO
UPPER 80S AND LOWS AROUND 70.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
WEAK UPPER TROUGHINESS TO OUR N AND NW...WHILE UPPER HIGH BUILDS
WESTWARD FROM THE ATLANTIC REMAINING CENTERED JUST TO OUR S AND SE.
SURFACE FRONT EXPECTED TO CONTINUE SLOWLY LIFTING NORTH OR
WEAKENING. IT APPEARS SUFFICIENT ATMOSPHERIC MOISTURE AND
INSTABILITY WILL REMAIN. MODEL CONSENSUS POPS ARE TRENDING
DOWN...THOUGH STILL ABOVE CL IMO AT LEAST THROUGH MIDWEEK...AND
WILL EXPECT POPS TO BECOME MORE DIURNALLY FAVORED WITH DAYTIME
HEATING. TEMPS SHOULD BEGIN TRENDING UP MORE TOWARDS CL IMO.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
CIGS ARE SLOWLY IMPROVING AND ARE MOSTLY MVFR AT THE TERMINALS AT
15Z. WILL EXPECT CONTINUED GRADUAL IMPROVEMENT IN CIGS WITH
DIURNAL HEATING AND WITH WEDGE SLOWLY ERODING/LIFTING NORTH.
LATEST HIGH RES MODELS INDICATING CONVECTION DEVELOPING ACROSS SE
GA BY MID AFTN...DRIFTING NORTH INTO OUR FA BY LATE AFTN/EVE. FOR
NOW...WILL HANDLE WITH VCSH AT AGS/DNL/OGB. WILL AMEND LATER FOR
STRONGER MENTION IF/WHEN CONFIDENCE WARRANTS. CIGS COULD LOWER
AGAIN TONIGHT AS WEDGE TRIES TO BUILD BACK TO THE
SOUTH...ESPECIALLY AT THE MORE NORTHERN TERMINALS CAE/CUB. WILL
ADDRESS THAT IN LATER TAF ISSUANCES.
EXTENDED AVIATION OUTLOOK...LATE NIGHT/EARLY MORNING
FOG/STRATUS. CHANCE OF AFTERNOON/EVENING THUNDERSTORMS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
1005 AM EDT SUN AUG 18 2013
.UPDATE...MODELS DEPICT SHORTWAVE IN MEAN FLOW MOVING FROM THE
GULF COAST UP THE WESTERN SIDE OF THE STATE. THIS HAS ALLOWED
FOCUS FOR RAINFALL TO SHIFT FROM THE SOUTHERN PORTIONS AS HAS BEEN
THE CASE THE PAST FEW DAYS TO MAINLY NORTHWEST GEORGIA THIS
MORNING. PROBLEMATIC FORECAST FOR THE REMAINDER OF TODAY WITH
SHORTWAVE CONTINUING TO EXERT INFLUENCE BUT ALSO MAJOR
CONTRIBUTING FACTORS FROM WEDGE AND HOW IT ERODES IF ANY AND
STATIONARY FRONT TO THE SOUTH AND HOW MUCH IT LIFTS NORTH IF ANY.
WILL LEAN TOWARD THE GFS WHICH HAS AN UNUSUAL SOLUTION OF A
STRONGER WEDGE THAN THE NAM12. THIS WILL KEEP FRONT TO THE SOUTH
AND WEDGE IN PLACE ALTHOUGH NOT QUITE AS STRONG AS YESTERDAY AS
EVIDENCED BY ATLANTAS TEMP OF 70 ALREADY. SHOULD SEE WAVES OF
PRECIP REDEVELOP WITH WESTERN SIDE REMAINING FAVORED. OTHER THAN
ELEVATED CONVECTION...FEEL THERE IS STILL AN OPPORTUNITY FOR SOME
SURFACE BASED ACTIVITY OVER THE EXTREME SOUTH LATE WHERE HRRR AND
WRF INDICATE MORE PRONOUNCED ACTIVITY. SHEAR IS MARGINAL BUT IN
VICINITY OF FRONT WILL NEED TO WATCH CLOSELY FOR ANY POTENTIAL
ROTATION IN STRONGER CELLS. OTHERWISE...FLOOD WATCH AND REMAINING
GRIDS LOOK ON TARGET AND NO CHANGES PLANNED.
&&
.PREV DISCUSSION... /ISSUED 734 AM EDT SUN AUG 18 2013/
SHORT TERM /TODAY THROUGH MONDAY/...
/ISSUED AT 445 AM EDT SUN AUG 18 2013/
LATEST SURFACE ANALYSIS SHOWS A WARM FRONT JUST SOUTH OF COLUMBUS
AND AUGUSTA...BUT JUST NORTH OF MACON. NAM AND ECMWF DRIFT THE FRONT
NORTHWARD AT LEAST INTO WEST CENTRAL GA THIS AFTERNOON AS THE UPPER
LOW CURRENTLY OVER WEST KY/TN BEGINS TO KICK EASTWARD LATER THIS
AFTERNOON. THE GFS HOLDS THE COOL WEDGE OVER THE NORTHEAST AND EAST
CENTRAL ZONES THROUGH TONIGHT...WHICH WILL MAKE TEMPS TRICKY TODAY.
SURFACE ANALYSIS ALSO SHOWS AN AREA OF LOW PRESSURE ALONG THE LA
COAST WHERE IT APPEARS TO BE DRIFTING NORTHWARD. NAM AND ECMWF DRIFT
THE SURFACE LOW WNW TODAY WHILE THE GFS DRIFTS IT NNE INTO SE LA.
THE GFS SEEMS TO INITIALIZE SLIGHTLY BETTER WITH THIS FEATURE AND
WITH THE UPPER LOW TO THE NORTH...WOULD NOT BE SURPRISED TO SEE THIS
SURFACE LOW DRIFT NNE AS THE GFS SUGGEST. THIS WOULD ALLOW THE WARM
FRONT TO ALSO DRIFT NORTH...AT LEAST INTO THE WEST CENTRAL ZONES
MAYBE FROM NEAR AUGUSTA TO ATLANTA TO ROME AS THE WEDGE MAY HOLD
STRONG FOR AREAS NE OF THIS LINE. EITHER WAY... MODELS SUGGEST THE
FRONT COULD PROVIDE A FOCUS FOR PERIODS OF HEAVY RAIN ACROSS THE NW
AND WEST CENTRAL ZONES TODAY...WHERE 1 TO 2 INCHES WITH ISOLATED
HIGHER AMOUNTS MAY BE POSSIBLY THROUGH 8 PM THIS EVENING AS THE
UPPER LOW BEGINS TO LIFT TO THE ENE. DECIDED TO PLAY IT SAFE AND
POST A FLASH FLOOD WATCH FOR THE WESTERN ZONES THROUGH 8 PM THIS
EVENING...GENERALLY FOR AREAS ALONG AND WEST OF A BLUE RIDGE TO
ATLANTA TO MACON LINE. THE WEDGE MAY HOLD STRONG ENOUGH TO THE EAST
TO ONLY ALLOW OCCASIONAL LIGHT TO MODERATE RAINS. WITH MUCH
UNCERTAINTY ON THE PROGRESSION OF THE WARM FRONT TODAY...
TEMPERATURES WILL BE VERY TRICKY. DECIDED TO TAKE A BLEND BETWEEN
THE WARMER MET AND COOLER MAV NUMBERS...WITH A LEAN TOWARD THE
COOLER GFS OVER THE EASTERN ZONES WHERE THE WEDGE WILL LIKELY
PERSIST. WILL ALSO WORD FOR ISOLATED THUNDERSTORMS ACROSS THE ENTIRE
FORECAST AREA THIS AFTERNOON AS THE UPPER LOW INTERACTS WITH
INCREASING INSTABILITIES ALONG AND SOUTH OF THE WARM FRONT. EXPECT
THE WEDGE INFLUENCE TO WEAKEN EVEN MORE ON MONDAY AS THE UPPER LOW
SHEARS OFF TO THE NE TONIGHT...LEAVING AN ACTIVE WEAK TROUGH IN ITS
PLACE. THIS COUPLED WITH HIGH PRESSURE OFF THE MID ATLANTIC COAST
WILL STILL PROVIDE FOR AN ESE WIND FLOW TONIGHT AND ON MONDAY. SO
DESPITE A WARMING TREND...STILL EXPECT WELL BELOW NORMAL HIGHS ON
MONDAY FOR MOST AREAS. A DEEPER SE WIND FLOW AND INCREASING
INSTABILITIES NORTHWARD WILL WARRANT A CHANCE OF THUNDERSTORMS ALL
ZONES FOR MONDAY AFTERNOON.
39
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
/ISSUED AT 445 AM EDT SUN AUG 18 2013/
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
HYDROLOGY...
/ISSUED AT 445 AM EDT SUN AUG 18 2013/
AN UPPER LOW PRESSURE SYSTEM TO THE NORTHWEST WILL INTERACT WITH A A
WARM FRONT DRIFTING NORTH TODAY TO PRODUCE A CHANCE OF HEAVY RAIN
ACROSS MAINLY NORTHWEST AND WEST CENTRAL GA TODAY. MODEL AND HPC QPF
NUMBERS SUGGEST ANYWHERE FROM 1 TO 2 INCHES WITH ISOLATED HIGHER
AMOUNTS IS POSSIBLE THROUGH THE AFTERNOON AND EVENING HOURS TODAY.
THEREFORE... HAVE POSTED A FLASH FLOOD WATCH THROUGH 8 PM THIS
EVENING FOR AREAS ALONG AND WEST OF A BLUE RIDGE TO ATLANTA TO MACON
LINE WHERE THE GREATEST RAINFALL AMOUNTS ARE EXPECTED. HOWEVER...
STILL MUCH UNCERTAINTY ON LOCATION...INTENSITY AND DURATION OF
CONVECTION THROUGH THE AFTERNOON AND EVENING HOURS...SO SOME AREAS
EAST OF THE WATCH COULD STILL SEE PERIODS OF BRIEF HEAVY RAIN. /39
CLIMATE...
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
AVIATION...
12Z UPDATE...
LIFR/IFR CIGS/VIS WILL GRADUALLY IMPROVE TO LOW MVFR CIGS BY 16-17Z
THIS MORNING... EXCEPT VFR AT CSG AND MCN BY THEN. GFS HOLDS THE
WEDGE IN OVER THE ATLANTA TAF SITES THROUGH TONIGHT... WHILE THE NAM
SHOWS A WARM/SE WIND FLOW SPREADING NORTH OF ATLANTA DURING THE
AFTERNOON. WILL LEAN TOWARD THE GFS AND HOLD WINDS ESE AT 8-10KTS
TODAY WITH PREVAILING MVFR CIGS AND -SHRA AS AMPLE MOISTURE
CONTINUES TO RIDE OVER THE COOL ESE SURFACE FLOW. MAY HEAR A RUMBLE
OF THUNDER THIS AFTERNOON AS THE WARM FRONT NEARS ATL...BUT WILL
CONTINUE TO JUST MENTION -SHRA FOR NOW. EXPECT IFR CIGS TO RETURN TO
ATL BY 02-03Z THIS EVENING...THEN POSSIBLY LIFR BY 06-08Z TONIGHT
WITH IMPROVEMENT TO MVFR BY 15Z MON...AND POSSIBLY VFR BY 18Z MON.
//ATL CONFIDENCE...12Z UPDATE...
MEDIUM ON ALL ELEMENTS.
39
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 75 69 81 70 / 50 50 50 40
ATLANTA 74 68 79 71 / 70 70 50 40
BLAIRSVILLE 71 65 77 65 / 70 70 50 30
CARTERSVILLE 74 68 80 70 / 80 70 50 30
COLUMBUS 82 71 82 72 / 100 60 50 40
GAINESVILLE 73 68 78 69 / 60 70 50 40
MACON 83 71 83 71 / 50 40 50 40
ROME 75 68 81 70 / 90 80 40 30
PEACHTREE CITY 76 67 80 70 / 60 60 50 40
VIDALIA 86 72 86 72 / 70 50 50 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...DEESE
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1050 AM EDT SUN AUG 18 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL BRING INCREASED CHANCES FOR RAIN
SOUTH OF PITTSBURGH THROUGH THE DAY SUNDAY...AND ALL LOCATIONS
SUNDAY NIGHT AND MONDAY. HIGH PRESSURE BY MID WEEK WILL PROVIDE
GENERALLY DRY AND WARM CONDITIONS.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WITH 1045AM UPDATE...PRIMARY CHANGE WAS TO BACK OFF POPS ACROSS
THE SOUTHEASTERN COUNTIES DURING THE AFTERNOON HOURS. CURRENT
RADAR AND HRRR FORECASTS INDICATE THAT THE RAINFALL ACROSS GARRETT
AND TUCKER COUNTIES HAS ALREADY REACHED ITS PEAK COVERAGE...WITH
RAIN BEGINNING TO PUSH OFF TO THE EAST. HAVE ACCORDINGLY DROPPED
POPS TO CHANCE BY THE AFTERNOON. MEANWHILE...ALTHOUGH RAIN HAS HAD
A HARD TIME PUSHING NORTH OF THE MASON-DIXON LINE SO FAR THIS
MORNING IN OHIO...THE RAIN SHOULD MAKE A RENEWED PUSH DURING THE
AFTERNOON HOURS. PREVIOUS DISCUSSION FOLLOWS.
WHILE THE LEADING SURFACE AND MID-LEVEL SYSTEM THAT WILL AFFECT
THE SOUTHEASTERN PORTIONS OF THE AREA THROUGH THE MORNING WILL
SHIFT OFF TO THE EAST BY AFTERNOON...THE MAIN UPPER LEVEL SYSTEM
WILL REMAIN WELL TO THE WEST OF THE AREA. AS IT SLOWLY
APPROACHES...AND THE JET STREAK MAXIMA CENTERS ITSELF NEARLY ALONG
THE NORTHWESTERN PERIPHERY OF THE FORECAST AREA BY
AFTERNOON...UPPER LEVEL DIVERGENCE SHOULD INCREASE AS THE RIGHT
ENTRANCE REGION OF THIS JET STREAK SURGES NORTHEASTWARD TOWARD OUR
AREA DURING THE AFTERNOON. AS SUCH...THE CHANCE OF SHOWERS LOOKS
TO AGAIN INCREASE FROM THE SOUTHWEST GOING INTO THE AFTERNOON. ALL
IN ALL...A CLOUDY DAY LOOKS TO BE IN STORE ACROSS THE REGION WITH
TEMPERATURES LIKELY HELD BACK FROM RECENT READINGS BECAUSE OF THE
CLOUDS. FRIES
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
UPR LOPRES OVER IN/KY WILL PHASE INTO BELT OF MDT WLYS OVER GRTLKS
RGN SUN NGT THRU MON. ALTHOUGH LIFT WILL DIMINISH THRU THIS TIME...
SHWRS XPCD TO FORM SUN NGT AND SPREAD ACRS MUCH OF THE FCST AREA
THRU MON. POPS WERE INCRD CNTRL/ERN ZONES.
POPS ALSO WERE DECRD MON NGT OWING TO RAPID PHASING AND DEPARTURE
OF THE WAVE AND INFLUENCE OF DVLPG SFC HIPRES IN ITS WAKE. A
SECOND SHRTWV TROF WILL APRCH THE RGN ON TUE...BUT LMTD MSTR WILL
LEAD TO WEAK INSTBY AND LKLY WILL SUPPRESS SHWR DVLPMT.
CLDS WILL LMT HEATING ON MON...WITH MAXIMA IN THE MID-UPR 70S
COMMON. BETTER HEATING XPCD ON TUE AS CLDS WILL BE LMTD TO DIURNAL
CU AMID TEMPS IN THE UPR 70S-LWR 80S.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
DRY WEATHER EXPECTED FOR EARLY PORTION OF LONG TERM WITH EASTERN
RIDGE AND LARGE SFC HIGH. STILL UNCERTAINTY WITH TIMING AND
EFFECTS OF WEAK COLD FRONT WHICH WILL PASS THROUGH THURSDAY
NIGHT/FRIDAY. WILL INCLUDE MENTION OF CHC/SCHC POPS LATE THU INTO
EARLY FRIDAY.
HIGH PRESSURE RETURNS BY THE WEEKEND.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS ARE EXPECTED THROUGH MOST OF THE FORECAST PERIOD.
RESTRICTIONS ARE POSSIBLE LATE THIS AFTERNOON AT ZZV AND
MGW...AND WILL INCLUDE TEMPO GROUP FOR MVFR CIG RESTRICTIONS.
.OUTLOOK.../MONDAY THROUGH THURSDAY/...
INCRG CVRG OF SHWRS AND TSTMS MAY LEAD TO OCNL CIG/VSBY
RESTRICTIONS MON. SFC HIPRES RETURNS BY MID-WK.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
724 AM EDT SUN AUG 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 344 AM EDT SUN AUG 18 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW UPR RDG STRETCHING
FM THE NCENTRAL PLAINS INTO THE UPR LKS TO THE S OF ZONAL FLOW OVER
SRN CANADA AND N OF CLOSED LO IN THE MID MS RIVER VALLEY. THE CWA IS
DOMINATED BY THE SW LLVL FLOW ON THE WRN FLANK OF SFC HI PRES OVER
THE NE CONUS. LOCAL 00Z RAOBS DEPICT SHARP SUBSIDENCE INVRN BTWN
H75-85 WITH DRY MID LVLS UNDER THE UPR RDG AXIS. THERE IS A SHRTWV
TRACKING EWD WITHIN THE ZONAL FLOW AND OVER A STNRY FNT IN
ONTARIO...BUT ONLY SOME HI CLDS ON THE SRN EDGE OF THIS DISTURBANCE
ARE SPILLING INTO LK SUP. THE SW FLOW ARND THE SFC HI TO THE E IS
TAPPING FAIRLY DRY LLVL AIR SHOWN ON THE 00Z MPX/GRB RAOBS...WHERE
THE H85 DEWPT WAS 7C AT BOTH SITES. MORE HUMID AIR IS PRESENT OVER
THE CENTRAL HI PLAINS...WHERE THE 00Z H85 DEWPT WAS 16C AT NORTH
PLATTE NEBRASKA.
MAIN FCST CONCERNS IN THE SHORT TERM WL BE TEMPS WITH SPRAWLING RDG
DOMINATING. LATER TNGT...FOCUS SHIFTS TO WHETHER THERE MIGHT BE A
FEW SHRA/TS OVER THE FAR WRN CWA AS SHRTWV EMBEDDED IN ZONAL FLOW
ALF TAPS SOME OF THE MORE HUMID H85 AIR IN THE CENTRAL HI PLAINS.
TDAY...WITH UPR RDG/SUBSIDENCE INVRN/MID LVL DRY AIR LINGERING OVER
UPR MI...EXPECT ANOTHER DRY DAY FOR UPR MI WITH NOTHING MORE THAN
SOME DIURNAL CU. H85 TEMPS ARE FCST TO BE 14-15C BY 00Z MON...UP TO
1C HIER THAN AT 00Z SUN. MIXING TO H8 AS OBSVD YDAY YIELDS HI TEMPS
80-85 AWAY FM THE MODERATING INFLUENCE OF LK MI IN CONTINUED LLVL SW
FLOW. THE DEEP MIXING MIGHT ALLOW FOR SOME GUSTS UP TO 20 MPH OVER
MAINLY THE NW CWA WHERE THE PRES GRADIENT WL BE A BIT TIGHTER/H925
WIND UP TO 20-25KTS. WITH MIN RH DROPPING TO ARND 35 PCT AS DEWPTS
MIX OUT DOWN TO THE LO 50S AND RECENT DRYNESS...FIRE WX CONCERNS WL
BE A BIT ELEVATED IN THAT AREA.
TNGT...MODELS REMAIN CONSISTENT SHOWING SHRTWV EMBEDDED IN ZONAL
FLOW OVER SRN SASKATCHEWAN SHIFTING ESEWD TOWARD THE UPR LKS AND
WEAKENING THE UPR RDG...WITH 00Z-12Z MON H5 HGT FALLS UP TO 40M OVER
THE CWA. AT THE SAME TIME...PERSISTENT SW FLOW IS PROGGED TO TAP
SOMEWHAT MORE HUMID H85 AIR NOW SHOWING UP IN THE CENTRAL PLAINS...
WITH FAIRLY VIGOROUS H85 THETA E ADVECTION INTO THE WRN CWA AFT 06Z.
THE MAIN PROBLEM FOR SHRA/TS DVLPMNT IS THE VERY DRY/STABLE
ANTECEDENT AIRMASS. IN FACT...NAM/GFS FCST SDNGS SHOW THE PROFILE
REMAINING TOO STABLE FOR CONVECTION EVEN OVER THE W EXCEPT PERHAPS
AT IWD TOWARD 12Z. ALTHOUGH THE BULK OF ANY SHRA/TS WL LIKELY BE TO
THE NW TOWARD LOWER HGTS/STNRY FNT IN ONTARIO...OPTED TO RETAIN
GOING SCHC POPS REACHING THE WRN LAND CWA IN THE 09Z-12Z TIME GIVEN
THE ARRIVAL OF THE HIER H85 THETA E...SSI FALLING TO NEAR -2C AND
AXIS OF H85-5 QVECTOR CNVGC FCST TO REACH THIS AREA IN THE 06Z-12Z
TIME. COMBINATION OF INCRSG PWAT TOWARD 1.5 INCH LATE OVER THE W AND
STEADY WSW H925 FLOW WITH WINDS UP TO 25-30KTS WL HOLD MIN TEMPS UP
OVER THE NW IN THE DOWNSLOPE AREAS NEAR LK SUP. BEST CHC FOR SOME
MINS IN THE COOLER 50S WL BE OVER THE INTERIOR SCENTRAL AND E...
WHERE WINDS WL BE LIGHTER AND DRIER AIR WL LINGER LONGEST.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 344 AM EDT SUN AUG 18 2013
MOST ATTENTION IN THE LONG TERM WAS FOCUSED ON TEMPS /MAINLY
THROUGH MID WEEK/ AND PRECIP /MAINLY WED INTO WED NIGHT/ WITH A COLD
FRONT MOVING INTO THE CWA.
LARGE SCALE WISE...AT 12Z MON...THERE WILL BE UPPER LEVEL HIGH
PRESSURE OVER MUCH OF THE CONUS...WITH ZONAL FLOW OVER CANADA. AT
THE SFC...THE CWA WILL BE BETWEEN HIGH PRESSURE COVERING MOST OF THE
CONUS AND A TROUGH OVER SASKATCHEWAN/MANITOBA. A SHORTWAVE WILL BE
OVER THE FAR WRN CWA AT 12Z MON...AND WILL TO THE CENTRAL CWA BY 18Z
MON. PRECIP WITH THE SHORTWAVE IS UNCERTAIN...BUT WILL CONTINUE TO
FAVOR LESSER PRECIP SOLUTIONS DUE TO THE SHORTWAVE PASSING BEFORE
PEAK HEATING AND THAT IT WILL BE PUSHING INTO HIGH PRESSURE.
STILL...MAY BE SOME ISOLATED SHOWERS/THUNDERSTORMS THAT TRY TO POP
UP. HIGHS WILL BE IN THE UPPER 70S TO MID 80S ON MON AS 850MB TEMPS
INCREASE TO AROUND 15C.
THE ZONAL FLOW WILL CONTINUE TO PUSH DYING PIECES OF ENERGY INTO THE
CWA TUE...BUT SAME STORY AS MON WITH THE SHORTWAVE PUSHING INTO THE
HIGH PRESSURE. BY 18Z TUE...850MB TEMPS WILL BE AROUND 18C...SO
HIGHS WILL BE EVEN WARMER IN THE 80S TO AROUND 90.
THE BIGGER QUESTION FOR THE FORECAST COMES ON WED AS A SFC
TROUGH/COLD FRONT MOVES INTO THE CWA LATER IN THE DAY INTO THE EARLY
OVERNIGHT HOURS WED NIGHT. GIVEN FORCING COMBINED WITH INSTABILITY
/CAPE VALUES AROUND 1500-2500 J/KG/ SHOULD LEAD TO SHOWERS AND
THUNDERSTORMS MOVING INTO/DEVELOPING ACROSS THE CWA. INCREASED POPS
SOME AS CONFIDENCE CONTINUES TO IMPROVE. WITH THE INSTABILITY AND
0-6KM BULK SHEAR AROUND 20KTS...A SEVERE STORM OR TWO CANNOT BE
RULED OUT...BUT IT IS STILL PRETTY EARLY FOR THAT DETERMINATION.
HIGHS ON WED LOOK TO BE SIMILAR TO TUESDAY.
POST COLD FROPA...THURSDAY IS THE MOST PREDICTABLE DAY AS COOLER
850MB TEMPS AROUND 14C WILL BE OVER THE CWA. THIS SHOULD RESULT IN
HIGHS IN THE 70S TO AROUND 80 /WARMEST SCENTRAL/. CONFIDENCE
DECREASES SIGNIFICANTLY AFTER THURSDAY AS MODELS SHOW WIDELY
DIFFERENT SOLUTIONS...MAINLY FOR TEMPS. THE ECMWF BRINGS A STRONG
UPPER RIDGE OVER THE REGION FRI INTO SAT...WHICH WOULD RESULT IN
VERY WARM TEMPS AGAIN. THE GFS KEEP THE STRONGEST PART OF THAT RIDGE
WELL TO OUR W...SO TEMPS ARE NOT AS WARM. WILL JUST GO WITH A
CONSENSUS OF MODEL GUIDANCE AT THIS TIME AND FOCUS ON SHORTER TERM
ISSUES.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 723 AM EDT SUN AUG 18 2013
WITH SW FLOW OF DRY AIR...EXPECT VFR CONDITIONS TO PREVAIL AT ALL 3
TAF SITES THIS FCST PERIOD. DAYTIME MIXING WL CAUSE A GUSTY WIND BY
LATE MRNG. THESE WINDS WL DIMINISH TOWARD SUNSET...BUT WITH INCRSG
SW WINDS ABOVE NOCTURNAL INVERSION TNGT...CONDITIONS WILL APPROACH
LLWS CRITERIA.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 344 AM 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 WINDS UP TO 20-25 KTS MAY
IMPACT THE W AND NCENTRAL TONIGHT UNDER A SHARPER PRES GRADIENT
AHEAD OF AN APPROACHING DISTURBANCE. THE ARRIVAL OF MORE HUMID AIR
FOR TUE/WED WILL RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE
WATERS. ANY FOG WILL DISSIPATE ON 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...TITUS
LONG TERM...KC
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1025 AM CDT SUN AUG 18 2013
.UPDATE...
ISSUED AT 1025 AM CDT SUN AUG 18 2013
A RATHER COMPLEX WEATHER PATTERN IS SETTING UP OVER WESTERN AND
CENTRAL NORTH DAKOTA TODAY. A SHORTWAVE OVER SOUTHERN MANITOBA HAS
FINALLY GENERATED ENOUGH LIFT FOR THE CAP TO BREAK SOUTH OF LAKE WINNIPEG.
A LINE OF THUNDERSTORMS HAVE DEVELOPED NEAR WINNIPEG ALONG A STALLED
SURFACE BOUNDARY EXTENDING INTO WESTERN AND CENTRAL NORTH DAKOTA.
DO NOT ANTICIPATED THUNDERSTORMS TO DEVELOP SOUTHWESTWARD ALONG
THIS BOUNDARY AS THE CAP (PER 12Z SOUNDING) APPEARS RATHER STRONG
OVER NORTH DAKOTA TODAY.
HOWEVER...A SECOND SHORTWAVE MOVING ACROSS MONTANA IS GENERATING
ELEVATED CONVECTION OVER EASTERN MONTANA INTO NORTHWESTERN SOUTH
DAKOTA. THIS WAVE WILL CONTINUE TO PUSH EAST OVER WESTERN AND
CENTRAL NORTH DAKOTA TODAY. THUNDERSTORMS SHOULD REMAIN ELEVATED
WEST THROUGH THE EARLY AFTERNOON. HOWEVER...AS THE WAVE MOVES INTO
CENTRAL NORTH DAKOTA LATER THIS AFTERNOON...THE CAP IS PROGGED TO
BEGIN TO ERODE AND THUNDERSTORMS COULD BECOME ROOTED IN THE
BOUNDARY LAYER ALONG THE AFOREMENTIONED STALLED FRONT. GIVEN THE
DEEPER CONVECTION POTENTIAL COMBINED WITH MUCAPE VALUES AROUND
2000 J/KG AND DEEP LAYER SHEAR BETWEEN 30-35 KNOTS...THINK THE
SEVERE THREAT WILL DEVELOP PRIMARILY OVER SOUTH CENTRAL AND
SOUTHEASTERN NORTH DAKOTA BETWEEN 22Z-03Z.
UPDATED THE FORECAST TO SPEED UP THE ONSET OF ELEVATED
THUNDERSTORMS WEST THIS MORNING BASED ON RADAR TRENDS. ALSO
REFOCUSED THE TIMING OF SEVERE THUNDERSTORM POTENTIAL TO LATER
THIS AFTERNOON/EVENING. THE UPDATED PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN CONCERN IN THE NEAR TERM WILL BE THE CHANCES OF
THUNDERSTORMS...INCLUDING THE POSSIBILITY OF SEVERE WEATHER.
EARLY MORNING WATER VAPOR IMAGERY SHOWED A WAVE MOVING ACROSS
SOUTHERN PARTS OF SASKATCHEWAN / MANITOBA...WITH ANOTHER WAVE IN
NORTHWEST MONTANA. CONVECTION WITH THE CANADIAN WAVE HAS BEEN
SPARSE...AND THE LATEST NAM / RAP KEEPS THE FORECAST AREA DRY
EARLY THIS MORNING AS THE WAVE PASSES. THE BIGGER CONCERN WILL BE
THE MONTANA WAVE AS IT INTERACTS WITH A WEAK BOUNDARY MOVING
THROUGH THE REGION. A FEW SHOWERS / THUNDERSTORMS ARE POSSIBLE IN
WESTERN NORTH DAKOTA LATER SUNDAY MORNING AS THE WAVE
APPROACHES...BUT DO NOT EXPECT THOSE TO BE SEVERE.
THE SEVERE THREAT IS EXPECTED TO INCREASE THIS AFTERNOON AND
EVENING AS THE MONTANA WAVE HELPS INITIATE THUNDERSTORMS ALONG THE
SLOW MOVING BOUNDARY. THAT BEING SAID...THE CAP REMAINS A
POTENTIAL LIMITING FACTOR DUE TO WARM H7 TEMPERATURES. THE NAM
AND GFS DISAGREE IN REGARDS TO HOW FAST THE MID LEVELS COOL
TODAY...WITH THE NAM BEING MORE AGGRESSIVE. THE NAM WAS ALSO
QUICKER TO INITIATE CONVECTION ALONG THE BOUNDARY ON
SATURDAY...AND AFTER SEEING THE LACK OF DEVELOPMENT ACROSS NORTH
DAKOTA...CONFIDENCE IN HOW WIDESPREAD THE CONVECTIVE DEVELOPMENT
WILL BE IS NOT HIGH. WILL CARRY CHANCE POPS NEAR THE BOUNDARY
TOWARDS LATE AFTERNOON / EARLY EVENING...AND LET LATER SHIFTS
MONITOR TRENDS WITH THE CAP AND POTENTIAL DEVELOPMENT.
IN REGARDS TO THE SEVERE WEATHER THREAT...EXPECT THE MAIN THREAT
AREA TO BE FROM THE SOUTH CENTRAL PART OF THE STATE AND TOWARDS
THE JAMES RIVER VALLEY. THE PRIMARY HAZARD SHOULD BE DAMAGING
WINDS WITH INVERTED V SOUNDINGS...WHILE WARM MID LEVEL
TEMPERATURES COULD LIMIT THE HAIL THREAT TO SOME DEGREE. ELEVATED
LIFTED CONDENSATION LEVELS SHOULD ALSO LIMIT THE TORNADO
POTENTIAL. THE THUNDERSTORM CHANCES ARE EXPECTED TO DIMINISH FROM
WEST TO EAST AS THE WAVE PASSES...WITH DRY WEATHER EXPECTED AGAIN
BY LATE TONIGHT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN HIGHLIGHTS IN THE EXTENDED WILL BE HOT TEMPERATURES
MONDAY AND TUESDAY...WELL INTO 90S...WITH NEAR RECORD HIGHS FOR
BISMARCK TUESDAY. THIS MAY LEAD TO A POSSIBLE HEAT ADVISORY
TUESDAY AFTERNOON ACROSS PORTIONS OF SOUTH CENTRAL NORTH DAKOTA. A
STRONG COLD FRONT WILL FOLLOW FOR TUESDAY NIGHT SUPPRESSING HIGHS
BACK INTO THE 80S FOR THE REST OF THE WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE PATTERN BECOMES MORE ACTIVE
WITH PERIODIC SHOWERS AND THUNDERSTORMS AS A PACIFIC LOW/TROUGH
EJECTS SEVERAL SHORTWAVES VIA A PERSISTENT FETCH OF SOUTHWEST FLOW
ALOFT STRAIGHT INTO NORTH DAKOTA.
FOR MONDAY AND TUESDAY...BEHIND A DEPARTING SHORTWAVE MONDAY MORNING
WILL BE BROAD RIDGING TAKING CONTROL. A LACK OF SHORTWAVE ACTIVITY
MONDAY WITH H85 TEMPS CLIMBING TO AROUND +26C TO +28C...BOTH MONDAY
AND TUESDAY...WILL MAKE THESE THE TWO HOTTEST DAYS IN THE EXTENDED.
PERHAPS A BIT WARMER TUESDAY. LOOKING AT RECORD HIGHS AT THE MAJOR
CITIES MONDAY AND TUESDAY...IT WOULD APPEAR THAT ONLY BISMARCK
WOULD COME CLOSEST TO POSSIBLY TYING A RECORD TUESDAY. THE RECORD IS
100 DEGREES SET BACK IN 1976. WE WILL BE CLOSE TO THAT WITH 98F AS A
FORECAST HIGH TEMPERATURE. WITH MANY SCHOOLS STARTING THIS
WEEK...HAVE TO REALLY CONSIDER THE HEAT IN THE AFTERNOON AS THE HEAT
INDICES WILL BE VERY CLOSE TO 100 DEGREES. WILL HIGHLIGHT THIS IN THE
HAZARDOUS WEATHER OUTLOOK FOR NOW AND BRIEF THE ONCOMING SHIFT THAT
AN ADVISORY MAY BECOME NECESSARY. GFS SOUNDINGS SHOW THAT ENOUGH OF
A CAP REMAINS IN PLACE THROUGH 00Z WEDNESDAY TO INHIBIT CONVECTION.
HAVE DISCOUNTED THE NAM SOLUTION WHICH GENERATES PRECIPITATION EARLY
IN THE DAY...WHILE THE OTHER MODELS KEEP IT DRY DURING THE DAYLIGHT
HOURS.
TUESDAY NIGHT/WEDNESDAY MORNING...A STRONG COLD FRONT WILL PUSH FROM
NORTHWEST TO SOUTHEAST. EXPECT A CHANCE FOR SHOWERS/THUNDERSTORMS
WITH THIS FRONT. H85 TEMPERATURES TAKE A DIGGER WITH +17C IN THE
NORTH WEDNESDAY AFTERNOON TO +20 IN THE SOUTHWEST. SHOULD BE
REFRESHING WITH HIGHS AROUND 80F NORTH TO MID 80S SOUTHWEST. THE
THREAT FOR AN ISOLATED SHOWER/THUNDERSTORM WILL LINGER IN THE SOUTH
THROUGH THE DAY WEDNESDAY.
THURSDAY THROUGH SUNDAY...SOUTHWEST FLOW ALOFT OPENS THE WAY FOR
SEVERAL SHORTWAVE TROUGHS TO MIGRATE THROUGH. UPPER RIDGE WILL BE
DOMINATE IN THE CENTRAL CONUS. THE TIMING OF THE AFOREMENTIONED
SHORTWAVES WILL CHANGE BETWEEN NOW AND LATER IN THE WEEK...BUT THE
HIGHER END CHANCES FOR SHOWERS/THUNDERSTORMS BEGIN TO INCREASE
THURSDAY AND CONTINUE INTO THE WEEKEND. THE ALLBLEND CAPTURES THIS
TREND WELL AND WILL MAINTAIN THAT. THE ECMWF IS A BIT MORE
AGGRESSIVE WITH THE SUCCESSIVE WAVES AND LARGER PRECIPITATION AREAS
VERSUS THE GFS...BUT THE OVERALL PATTERN IN BOTH MODELS IS SIMILAR.
HIGHS WILL REMAIN IN THE 80S WITH LOWS IN THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 633 AM CDT SUN AUG 18 2013
FOG HAS DEVELOPED EARLY THIS MORNING IN NORTHWEST NORTH DAKOTA.
WILL ADD FOG TO KISN FOR A FEW HOURS THIS MORNING...WITH IMPROVEMENT
EXPECTED BY MID MORNING AS PER THE HRRR. 11-3.9 MICRON SATELLITE
IMAGERY SUGGESTS A SMALL AREA OF STRATUS COULD MOVE INTO KJMS IN THE
NEXT HOUR OR TWO. WILL CARRY A CEILING AROUND 700 FT TO START THE
FORECAST...AND THEN TREND TO VFR BY MID MORNING.
THE CHANCE OF THUNDERSTORMS WILL BE A CONCERN FOR ALL TAF SITES AS
AN UPPER LEVEL DISTURBANCE MOVES ACROSS THE REGION TODAY. WILL
CARRY VCTS AT THE AERODROMES...BUT AM NOT CONFIDENT ENOUGH IN THE
TIMING TO ADD A TEMPO OR PREVAILING GROUP. THE THUNDERSTORM THREAT
SHOULD END FROM WEST TO EAST...WITH DRY WEATHER AGAIN AT ALL
AERODROMES LATER TONIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
633 AM CDT SUN AUG 18 2013
.UPDATE ISSUED AT 633 AM CDT SUN AUG 18 2013...
THE LATEST FOG/STRATUS LOOP SHOWS A COUPLE OF PROBLEM AREAS. ONE
WAS SEEN OVER NORTHWEST NORTH DAKOTA WITH CROSBY HAVING
VISIBILITIES OF LESS THAN A QUARTER OF A MILE...BUT THIS IS
ISOLATED AS TIOGA WAS AT 3 MILES. MID/UPPER LEVEL CLOUDS ARE
APPROACHING AND THIS SHOULD HELP VISIBILITIES IMPROVE A BIT. WILL
MONITOR AND ISSUE A NOW-CAST TO COVER THE ISOLATED DENSE FOG AREA
NEAR CROSBY. THE OTHER AREA WAS IN THE FAR SOUTHEAST...FROM ASHLEY
TO JAMESTOWN WHERE A COMBINATION OF FOG/STRATUS WAS OCCURRING.
LOCAL/REGIONAL RADAR IS NOW SHOWING ISOLATED SHOWERS WORKING THEIR
WAY INTO WESTERN NORTH DAKOTA...WITH LIGHTNING CONFINED FROM GLASGOW
WEST. CURRENT FORECAST REMAINS ON TRACK.
UPDATE ISSUED AT 533 AM CDT SUN AUG 18 2013
SENT A QUICK UPDATE TO ADD PATCHY FOG TO THE NORTHWEST. THE HRRR
VISIBILITY FORECAST APPEARS TO HAVE A GOOD HANDLE ON THE
SITUATION...AND WILL FOLLOW ITS GENERAL TREND. THE REMAINDER OF
THE FORECAST IS STILL ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN CONCERN IN THE NEAR TERM WILL BE THE CHANCES OF
THUNDERSTORMS...INCLUDING THE POSSIBILITY OF SEVERE WEATHER.
EARLY MORNING WATER VAPOR IMAGERY SHOWED A WAVE MOVING ACROSS
SOUTHERN PARTS OF SASKATCHEWAN / MANITOBA...WITH ANOTHER WAVE IN
NORTHWEST MONTANA. CONVECTION WITH THE CANADIAN WAVE HAS BEEN
SPARSE...AND THE LATEST NAM / RAP KEEPS THE FORECAST AREA DRY
EARLY THIS MORNING AS THE WAVE PASSES. THE BIGGER CONCERN WILL BE
THE MONTANA WAVE AS IT INTERACTS WITH A WEAK BOUNDARY MOVING
THROUGH THE REGION. A FEW SHOWERS / THUNDERSTORMS ARE POSSIBLE IN
WESTERN NORTH DAKOTA LATER SUNDAY MORNING AS THE WAVE
APPROACHES...BUT DO NOT EXPECT THOSE TO BE SEVERE.
THE SEVERE THREAT IS EXPECTED TO INCREASE THIS AFTERNOON AND
EVENING AS THE MONTANA WAVE HELPS INITIATE THUNDERSTORMS ALONG THE
SLOW MOVING BOUNDARY. THAT BEING SAID...THE CAP REMAINS A
POTENTIAL LIMITING FACTOR DUE TO WARM H7 TEMPERATURES. THE NAM
AND GFS DISAGREE IN REGARDS TO HOW FAST THE MID LEVELS COOL
TODAY...WITH THE NAM BEING MORE AGGRESSIVE. THE NAM WAS ALSO
QUICKER TO INITIATE CONVECTION ALONG THE BOUNDARY ON
SATURDAY...AND AFTER SEEING THE LACK OF DEVELOPMENT ACROSS NORTH
DAKOTA...CONFIDENCE IN HOW WIDESPREAD THE CONVECTIVE DEVELOPMENT
WILL BE IS NOT HIGH. WILL CARRY CHANCE POPS NEAR THE BOUNDARY
TOWARDS LATE AFTERNOON / EARLY EVENING...AND LET LATER SHIFTS
MONITOR TRENDS WITH THE CAP AND POTENTIAL DEVELOPMENT.
IN REGARDS TO THE SEVERE WEATHER THREAT...EXPECT THE MAIN THREAT
AREA TO BE FROM THE SOUTH CENTRAL PART OF THE STATE AND TOWARDS
THE JAMES RIVER VALLEY. THE PRIMARY HAZARD SHOULD BE DAMAGING
WINDS WITH INVERTED V SOUNDINGS...WHILE WARM MID LEVEL
TEMPERATURES COULD LIMIT THE HAIL THREAT TO SOME DEGREE. ELEVATED
LIFTED CONDENSATION LEVELS SHOULD ALSO LIMIT THE TORNADO
POTENTIAL. THE THUNDERSTORM CHANCES ARE EXPECTED TO DIMINISH FROM
WEST TO EAST AS THE WAVE PASSES...WITH DRY WEATHER EXPECTED AGAIN
BY LATE TONIGHT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN HIGHLIGHTS IN THE EXTENDED WILL BE HOT TEMPERATURES
MONDAY AND TUESDAY...WELL INTO 90S...WITH NEAR RECORD HIGHS FOR
BISMARCK TUESDAY. THIS MAY LEAD TO A POSSIBLE HEAT ADVISORY
TUESDAY AFTERNOON ACROSS PORTIONS OF SOUTH CENTRAL NORTH DAKOTA. A
STRONG COLD FRONT WILL FOLLOW FOR TUESDAY NIGHT SUPPRESSING HIGHS
BACK INTO THE 80S FOR THE REST OF THE WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE PATTERN BECOMES MORE ACTIVE
WITH PERIODIC SHOWERS AND THUNDERSTORMS AS A PACIFIC LOW/TROUGH
EJECTS SEVERAL SHORTWAVES VIA A PERSISTENT FETCH OF SOUTHWEST FLOW
ALOFT STRAIGHT INTO NORTH DAKOTA.
FOR MONDAY AND TUESDAY...BEHIND A DEPARTING SHORTWAVE MONDAY MORNING
WILL BE BROAD RIDGING TAKING CONTROL. A LACK OF SHORTWAVE ACTIVITY
MONDAY WITH H85 TEMPS CLIMBING TO AROUND +26C TO +28C...BOTH MONDAY
AND TUESDAY...WILL MAKE THESE THE TWO HOTTEST DAYS IN THE EXTENDED.
PERHAPS A BIT WARMER TUESDAY. LOOKING AT RECORD HIGHS AT THE MAJOR
CITIES MONDAY AND TUESDAY...IT WOULD APPEAR THAT ONLY BISMARCK
WOULD COME CLOSEST TO POSSIBLY TYING A RECORD TUESDAY. THE RECORD IS
100 DEGREES SET BACK IN 1976. WE WILL BE CLOSE TO THAT WITH 98F AS A
FORECAST HIGH TEMPERATURE. WITH MANY SCHOOLS STARTING THIS
WEEK...HAVE TO REALLY CONSIDER THE HEAT IN THE AFTERNOON AS THE HEAT
INDICES WILL BE VERY CLOSE TO 100 DEGREES. WILL HIGHLIGHT THIS IN THE
HAZARDOUS WEATHER OUTLOOK FOR NOW AND BRIEF THE ONCOMING SHIFT THAT
AN ADVISORY MAY BECOME NECESSARY. GFS SOUNDINGS SHOW THAT ENOUGH OF
A CAP REMAINS IN PLACE THROUGH 00Z WEDNESDAY TO INHIBIT CONVECTION.
HAVE DISCOUNTED THE NAM SOLUTION WHICH GENERATES PRECIPITATION EARLY
IN THE DAY...WHILE THE OTHER MODELS KEEP IT DRY DURING THE DAYLIGHT
HOURS.
TUESDAY NIGHT/WEDNESDAY MORNING...A STRONG COLD FRONT WILL PUSH FROM
NORTHWEST TO SOUTHEAST. EXPECT A CHANCE FOR SHOWERS/THUNDERSTORMS
WITH THIS FRONT. H85 TEMPERATURES TAKE A DIGGER WITH +17C IN THE
NORTH WEDNESDAY AFTERNOON TO +20 IN THE SOUTHWEST. SHOULD BE
REFRESHING WITH HIGHS AROUND 80F NORTH TO MID 80S SOUTHWEST. THE
THREAT FOR AN ISOLATED SHOWER/THUNDERSTORM WILL LINGER IN THE SOUTH
THROUGH THE DAY WEDNESDAY.
THURSDAY THROUGH SUNDAY...SOUTHWEST FLOW ALOFT OPENS THE WAY FOR
SEVERAL SHORTWAVE TROUGHS TO MIGRATE THROUGH. UPPER RIDGE WILL BE
DOMINATE IN THE CENTRAL CONUS. THE TIMING OF THE AFOREMENTIONED
SHORTWAVES WILL CHANGE BETWEEN NOW AND LATER IN THE WEEK...BUT THE
HIGHER END CHANCES FOR SHOWERS/THUNDERSTORMS BEGIN TO INCREASE
THURSDAY AND CONTINUE INTO THE WEEKEND. THE ALLBLEND CAPTURES THIS
TREND WELL AND WILL MAINTAIN THAT. THE ECMWF IS A BIT MORE
AGGRESSIVE WITH THE SUCCESSIVE WAVES AND LARGER PRECIPITATION AREAS
VERSUS THE GFS...BUT THE OVERALL PATTERN IN BOTH MODELS IS SIMILAR.
HIGHS WILL REMAIN IN THE 80S WITH LOWS IN THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 633 AM CDT SUN AUG 18 2013
FOG HAS DEVELOPED EARLY THIS MORNING IN NORTHWEST NORTH DAKOTA.
WILL ADD FOG TO KISN FOR A FEW HOURS THIS MORNING...WITH IMPROVEMENT
EXPECTED BY MID MORNING AS PER THE HRRR. 11-3.9 MICRON SATELLITE
IMAGERY SUGGESTS A SMALL AREA OF STRATUS COULD MOVE INTO KJMS IN THE
NEXT HOUR OR TWO. WILL CARRY A CEILING AROUND 700 FT TO START THE
FORECAST...AND THEN TREND TO VFR BY MID MORNING.
THE CHANCE OF THUNDERSTORMS WILL BE A CONCERN FOR ALL TAF SITES AS
AN UPPER LEVEL DISTURBANCE MOVES ACROSS THE REGION TODAY. WILL
CARRY VCTS AT THE AERODROMES...BUT AM NOT CONFIDENT ENOUGH IN THE
TIMING TO ADD A TEMPO OR PREVAILING GROUP. THE THUNDERSTORM THREAT
SHOULD END FROM WEST TO EAST...WITH DRY WEATHER AGAIN AT ALL
AERODROMES LATER TONIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
533 AM CDT SUN AUG 18 2013
.UPDATE...
ISSUED AT 533 AM CDT SUN AUG 18 2013
SENT A QUICK UPDATE TO ADD PATCHY FOG TO THE NORTHWEST. THE HRRR
VISIBLITY FORECAST APPEARS TO HAVE A GOOD HANDLE ON THE
SITUATION...AND WILL FOLLOW ITS GENERAL TREND. THE REMAINDER OF
THE FORECAST IS STILL ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN CONCERN IN THE NEAR TERM WILL BE THE CHANCES OF
THUNDERSTORMS...INCLUDING THE POSSIBILITY OF SEVERE WEATHER.
EARLY MORNING WATER VAPOR IMAGERY SHOWED A WAVE MOVING ACROSS
SOUTHERN PARTS OF SASKATCHEWAN / MANITOBA...WITH ANOTHER WAVE IN
NORTHWEST MONTANA. CONVECTION WITH THE CANADIAN WAVE HAS BEEN
SPARSE...AND THE LATEST NAM / RAP KEEPS THE FORECAST AREA DRY
EARLY THIS MORNING AS THE WAVE PASSES. THE BIGGER CONCERN WILL BE
THE MONTANA WAVE AS IT INTERACTS WITH A WEAK BOUNDARY MOVING
THROUGH THE REGION. A FEW SHOWERS / THUNDERSTORMS ARE POSSIBLE IN
WESTERN NORTH DAKOTA LATER SUNDAY MORNING AS THE WAVE
APPROACHES...BUT DO NOT EXPECT THOSE TO BE SEVERE.
THE SEVERE THREAT IS EXPECTED TO INCREASE THIS AFTERNOON AND
EVENING AS THE MONTANA WAVE HELPS INITIATE THUNDERSTORMS ALONG THE
SLOW MOVING BOUNDARY. THAT BEING SAID...THE CAP REMAINS A
POTENTIAL LIMITING FACTOR DUE TO WARM H7 TEMPERATURES. THE NAM
AND GFS DISAGREE IN REGARDS TO HOW FAST THE MID LEVELS COOL
TODAY...WITH THE NAM BEING MORE AGGRESSIVE. THE NAM WAS ALSO
QUICKER TO INITIATE CONVECTION ALONG THE BOUNDARY ON
SATURDAY...AND AFTER SEEING THE LACK OF DEVELOPMENT ACROSS NORTH
DAKOTA...CONFIDENCE IN HOW WIDESPREAD THE CONVECTIVE DEVELOPMENT
WILL BE IS NOT HIGH. WILL CARRY CHANCE POPS NEAR THE BOUNDARY
TOWARDS LATE AFTERNOON / EARLY EVENING...AND LET LATER SHIFTS
MONITOR TRENDS WITH THE CAP AND POTENTIAL DEVELOPMENT.
IN REGARDS TO THE SEVERE WEATHER THREAT...EXPECT THE MAIN THREAT
AREA TO BE FROM THE SOUTH CENTRAL PART OF THE STATE AND TOWARDS
THE JAMES RIVER VALLEY. THE PRIMARY HAZARD SHOULD BE DAMAGING
WINDS WITH INVERTED V SOUNDINGS...WHILE WARM MID LEVEL
TEMPERATURES COULD LIMIT THE HAIL THREAT TO SOME DEGREE. ELEVATED
LIFTED CONDENSATION LEVELS SHOULD ALSO LIMIT THE TORNADO
POTENTIAL. THE THUNDERSTORM CHANCES ARE EXPECTED TO DIMINISH FROM
WEST TO EAST AS THE WAVE PASSES...WITH DRY WEATHER EXPECTED AGAIN
BY LATE TONIGHT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN HIGHLIGHTS IN THE EXTENDED WILL BE HOT TEMPERATURES
MONDAY AND TUESDAY...WELL INTO 90S...WITH NEAR RECORD HIGHS FOR
BISMARCK TUESDAY. THIS MAY LEAD TO A POSSIBLE HEAT ADVISORY
TUESDAY AFTERNOON ACROSS PORTIONS OF SOUTH CENTRAL NORTH DAKOTA. A
STRONG COLD FRONT WILL FOLLOW FOR TUESDAY NIGHT SUPPRESSING HIGHS
BACK INTO THE 80S FOR THE REST OF THE WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE PATTERN BECOMES MORE ACTIVE
WITH PERIODIC SHOWERS AND THUNDERSTORMS AS A PACIFIC LOW/TROUGH
EJECTS SEVERAL SHORTWAVES VIA A PERSISTENT FETCH OF SOUTHWEST FLOW
ALOFT STRAIGHT INTO NORTH DAKOTA.
FOR MONDAY AND TUESDAY...BEHIND A DEPARTING SHORTWAVE MONDAY MORNING
WILL BE BROAD RIDGING TAKING CONTROL. A LACK OF SHORTWAVE ACTIVITY
MONDAY WITH H85 TEMPS CLIMBING TO AROUND +26C TO +28C...BOTH MONDAY
AND TUESDAY...WILL MAKE THESE THE TWO HOTTEST DAYS IN THE EXTENDED.
PERHAPS A BIT WARMER TUESDAY. LOOKING AT RECORD HIGHS AT THE MAJOR
CITIES MONDAY AND TUESDAY...IT WOULD APPEAR THAT ONLY BISMARCK
WOULD COME CLOSEST TO POSSIBLY TYING A RECORD TUESDAY. THE RECORD IS
100 DEGREES SET BACK IN 1976. WE WILL BE CLOSE TO THAT WITH 98F AS A
FORECAST HIGH TEMPERATURE. WITH MANY SCHOOLS STARTING THIS
WEEK...HAVE TO REALLY CONSIDER THE HEAT IN THE AFTERNOON AS THE HEAT
INDICES WILL BE VERY CLOSE TO 100 DEGREES. WILL HIGHLIGHT THIS IN THE
HAZARDOUS WEATHER OUTLOOK FOR NOW AND BRIEF THE ONCOMING SHIFT THAT
AN ADVISORY MAY BECOME NECESSARY. GFS SOUNDINGS SHOW THAT ENOUGH OF
A CAP REMAINS IN PLACE THROUGH 00Z WEDNESDAY TO INHIBIT CONVECTION.
HAVE DISCOUNTED THE NAM SOLUTION WHICH GENERATES PRECIPITATION EARLY
IN THE DAY...WHILE THE OTHER MODELS KEEP IT DRY DURING THE DAYLIGHT
HOURS.
TUESDAY NIGHT/WEDNESDAY MORNING...A STRONG COLD FRONT WILL PUSH FROM
NORTHWEST TO SOUTHEAST. EXPECT A CHANCE FOR SHOWERS/THUNDERSTORMS
WITH THIS FRONT. H85 TEMPERATURES TAKE A DIGGER WITH +17C IN THE
NORTH WEDNESDAY AFTERNOON TO +20 IN THE SOUTHWEST. SHOULD BE
REFRESHING WITH HIGHS AROUND 80F NORTH TO MID 80S SOUTHWEST. THE
THREAT FOR AN ISOLATED SHOWER/THUNDERSTORM WILL LINGER IN THE SOUTH
THROUGH THE DAY WEDNESDAY.
THURSDAY THROUGH SUNDAY...SOUTHWEST FLOW ALOFT OPENS THE WAY FOR
SEVERAL SHORTWAVE TROUGHS TO MIGRATE THROUGH. UPPER RIDGE WILL BE
DOMINATE IN THE CENTRAL CONUS. THE TIMING OF THE AFOREMENTIONED
SHORTWAVES WILL CHANGE BETWEEN NOW AND LATER IN THE WEEK...BUT THE
HIGHER END CHANCES FOR SHOWERS/THUNDERSTORMS BEGIN TO INCREASE
THURSDAY AND CONTINUE INTO THE WEEKEND. THE ALLBLEND CAPTURES THIS
TREND WELL AND WILL MAINTAIN THAT. THE ECMWF IS A BIT MORE
AGGRESSIVE WITH THE SUCCESSIVE WAVES AND LARGER PRECIPITATION AREAS
VERSUS THE GFS...BUT THE OVERALL PATTERN IN BOTH MODELS IS SIMILAR.
HIGHS WILL REMAIN IN THE 80S WITH LOWS IN THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 320 AM CDT SUN AUG 18 2013
STRATUS DEVELOPMENT WILL HAVE TO BE MONITORED AGAIN EARLY THIS
MORNING...BUT THE STRATUS IS MUCH FARTHER SOUTH THAN YESTERDAY AT
THIS TIME. THE NAM STILL INCREASES H925 RELATIVE HUMIDITY ACROSS
SOUTH CENTRAL NORTH DAKOTA INTO THE JAMES RIVER VALLEY...AND WILL
HINT AT POSSIBLE STRATUS WITH SCATTED CLOUDS AROUND 1500 FT AT
KJMS.
THE NEXT CONCERN WILL BE THE CHANCE OF THUNDERSTORMS AS A FRONTAL
BOUNDARY MOVES ACROSS THE REGION. CONFIDENCE IN TIMING / PLACEMENT
OF THE CONVECTION IS STILL NOT HIGH...AND WILL CARRY VCTS AT THE
TERMINALS TO SUGGEST THUNDERSTORMS ARE POSSIBLE. OVERALL...WILL
STAY WITH VFR FORECASTS AND MONITOR TRENDS EARLY THIS MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CK
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
854 AM CDT SUN AUG 18 2013
.UPDATE...
RADAR CURRENTLY SHOWING LITTLE IF ANY SHOWER ACTIVITY THIS
MORNING. AS THE CLOSED UPPER LOW BEGINS TO OPEN UP AND WEAKEN
LATER TODAY...SOME ATMOSPHERIC DRYING CAN BE EXPECTED WITH TIME.
850 MB FLOW SHOWING SOME CYCLONIC CURVATURE BUT THE BETTER
CONVERGENCE IS WELL SOUTH. PLENTY OF CLOUDINESS AROUND AND THAT
WILL PREVENT MUCH IN THE WAY OF CAPE BUILDUP IN THE AFTERNOON.
HOWEVER...LATEST HRRR STILL SHOWING SOME DEVELOPMENT LATER THIS
MORNING WITH THE ACTIVITY EXPECTED TO LIFT NORTHWARD.
FOR THE UPDATE...WILL LOWER POPS TO A SMALL DEGREE ACROSS EASTERN
AND CENTRAL AREAS. OTW...REMAINDER OF FCST APPEARS TO BE ON TRACK.
&&
.PREV DISCUSSION... /ISSUED 535 AM CDT SUN AUG 18 2013/
UPDATE...FOR 12Z AVIATION FORECASTS.
AVIATION...EXPECT IFR CONDITIONS AT CSV AND CKV THROUGH 16Z AND
MVFR CONDITIONS AT BNA. CONDITIONS AT ALL STATIONS GENERALLY
IMPROVING TO VFR BY 16Z-19Z AND CONTINUING THROUGH 01Z. AFTER 01Z
EXPECT CONDITIONS TO, ONCE AGAIN, DETERIORATE TO MVFR AND IFR
CONDITIONS, WITH LOWERING CIGS AND DEVELOPMENT OF PATCHY FOG.
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE ALSO EXPECTED
DURING THE FORECAST PERIOD.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
21
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
942 AM EDT SUN AUG 18 2013
.SYNOPSIS...
A COOL WEDGE OF HIGH PRESSURE WILL REMAIN SITUATED ALONG
THE LEE OF THE CENTRAL APPALACHIANS THIS MORNING BEFORE
SLOWLY WEAKENING FROM WEST TO EAST THIS AFTERNOON. LOW
PRESSURE TRACKING ALONG COASTAL NORTH CAROLINA WILL PASS
OFFSHORE LATER TODAY AHEAD OF ANOTHER UPPER LEVEL DISTURBANCE
THAT WILL AFFECT THE MOUNTAINS OVERNIGHT. THIS UPPER LEVEL
TROUGH OF LOW PRESSURE IS EXPECTED TO PASS ACROSS THE REGION
FROM THE WEST MONDAY KEEPING THE THREAT OF SHOWERS AROUND
INTO MONDAY EVENING.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM EDT SUNDAY...
12Z RNK SOUNDING SHOWS AN IMPRESSIVE WEDGE FOR LATE AUGUST WITH
EAST/NORTHEAST WINDS UP TO 750 MB. ABV THIS LAYER...WINDS HAVE
ALREADY VEERED TO THE SOUTHWEST AND THESE VEERING WINDS ABV THE
WEDGE WILL CONTINUE THROUGH THE DAY RESULTING IN A MORE SHALLOW
LAYER OF MOISTURE AND REDUCED PRECIP RATES.
CHANNELED VORTICITY MOVING THROUGH THE SOUTHWEST FLOW ALOFT WILL
CONTINUE TO GENERATE LIGHT PRECIP...ESPECIALLY ALONG THE THE BLUE
RIDGE AND THE EASTERN SLOPES WITH A LOW LEVEL EASTERLY COMPONENT
TO THE WIND. THEREFORE...CONTINUED LIKELY POPS FOR THIS AREA
THROUGH MUCH OF THE DAY.
VISIBLE SATELLITE IMAGERY IS SHOWING SOME BREAKS IN THE CLOUDS
ACROSS FAR SW VA AND NE TN. MESOSCALE MODELS INCLUDING THE LOCAL
WRF AND HRRR SUGGEST THESE BREAKS MAY EXPAND INTO THE FAR WESTERN
PORTION OF THE FORECAST AREA...INCLUDING NW NC...THE MOUNTAIN
EMPIRE...THE CLINCH VALLEY AND PERHAPS BLF. THIS WILL GENERATE
SOME INSTABILITY AND MAY IGNITE SCATTERED SHOWERS AND ISOLATED
STORMS LATE THIS AFTERNOON.
IN THE EAST...BROUGHT DOWN HIGH TEMPS A COUPLE OF DEGREES AS WE
EXPECT THE WEDGE TO HOLD IN THIS AREA THROUGH THE DAY.
UPPER LOW OPENS UP THIS EVENING WITH CHANNELED VORTICITY CLIPPING
ACROSS THE WEST OVERNIGHT. FORECAST PWATS SHOW SOME DECREASE PER
MORE OF A WEST/SW FLOW...WHILE DYNAMICS LOOK QUITE GOOD UNDER THE
RIGHT REAR OF A 3H JET MAX. PROGGED SWATH OF LOW LEVEL CONVERGENCE
ALSO INDICATED ESPCLY OVER THE SOUTHERN TIER THROUGH MUCH OF THE
NIGHT. MODELS IN TURN DEVELOP A BAND OF CONVECTION OVER THE WEST
EARLY TONIGHT...AND MOVE IT EAST ACROSS THE SOUTHERN TIER COUNTIES
WITH SOME DEGREE OF UNCERTAINTY IN HOW ORGANZIED COVERAGE MAY BE.
THINK ENOUGH CONFIDENCE TO INCLUDE ANOTHER ROUND OF LIKELY POPS
SOUTH TONIGHT WITH DECENT CHANCES ELSW EXCEPT PERHAPS THE FAR EAST
WHERE SOME OF THE WEDGE MAY STILL BE LINGERING. KEPT LOWS IN
BETWEEN THE COOLER MET AND WARMER MAV MOS GIVEN CLOUDS/SHRA AND
ONLY A SLIGHT DECREASE IN DEWPOINTS LATE.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
AS OF 256 AM EDT SUNDAY...
A CLOSED LOW TO THE WEST WILL OPEN INTO A TROUGH ON MONDAY
AS IT TRACKS OVER THE OHIO VALLEY. MODELS SHOWING ONE
SIGNIFICANT SHORT WAVE COMING ACROSS THE AREA MONDAY
MORNING...THEN ANY SHORT WAVES IN THE AFTERNOON STAY SOUTH.
WILL HAVE THE HIGHEST POPS FOR SHOWERS IN THE MORNING...TAPERING
TO SCATTERED CONVECTION IN THE AFTERNOON. FROM MONDAY
AFTERNOON INTO MID WEEK...THE WEATHER PATTERN SHIFTS BACK TO
MOSTLY DIURNAL CONVECTION...FIRING IN THE AFTERNOON...WANING
DURING THE EVENING. THE BEST AREAL COVERAGE OF CONVECTION WILL
BE TO THE SOUTH WHERE THE HIGHEST AMOUNT OF MOISTURE WILL RESIDE.
MORNING SHOWERS AND CLOUDS WILL KEEP MONDAY AFTERNOONS HIGH A
FEW DEGREES COOLER THAN NORMAL. HOWEVER...TEMPERATURES WILL BE
WARMER THAN THIS WEEKEND WITH 70S IN THE WEST TO LOWER 80S IN
THE EAST. TEMPERATURES ARE BACK TO NORMAL ON TUESDAY WITH NEAR
80F IN THE WEST TO MID TO UPPER 80S ACROSS THE EAST.
&&
.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 /14Z SUNDAY THROUGH THURSDAY/...
AS OF 700 AM EDT SUNDAY...
POOR FLYING CONDITIONS WILL PERSIST INTO THIS AFTERNOON AS A
WEDGE OF COOL AIR AGAINST THE EASTERN SLOPES OF THE MOUNTAINS
KEEPS LOW CIGS AND SPOTTY -RA/-DZ IN PLACE. MAY SEE SOME
IMPROVEMENT OVER THE WESTERN LOCATIONS...MAINLY KBLF/KLWB BY
AFTERNOON WHEN A PERIOD OF VFR LOOKS LIKELY ESPCLY AROUND KBLF.
OTRW VEERING FLOW ALOFT WITH LOW PRESSURE ALONG THE COAST AND
UPPER ENERGY PASSING ACROSS WILL KEEP WIDESPREAD LIGHT TO MODERATE
RAIN GOING ESPCLY BLUE RIDGE THIS MORNING WHERE AIDED BY EASTERLY
UPSLOPE FLOW. THIS SHOULD MAKE FOR CONTINUED MVFR/IFR THROUGH
MIDDAY SUNDAY BEFORE THE WEDGE STARTS TO WEAKEN FROM WEST TO EAST.
LOW CONFIDENCE IN JUST HOW FAST THE IFR CIGS MAY LIFT FROM
KROA/KBCB EAST AS SOUNDINGS INDICATE THE WEDGE HOLDING FOR MUCH
OF THE DAY WHILE ERODING FAR WEST AHEAD OF ANOTHER PIECE OF UPPER
LEVEL LOW PRESSURE. GIVEN TIMING BEING MID AUGUST WILL SHOW MORE
IMPROVEMENT TO MVFR AT KDAN LATER THIS AFTERNOON WITH SOME
LINGERING -RA/-DZ TAPERING TO PATCHY FOG WHICH COULD LINGER INTO
THE EVENING. KBCB LOOKS TO BE THE BREAK BETWEEN THE WEDGE ERODING
IN THE WEST AND LOW CIGS LINGERING IN THE EAST SO LEANED MORE
PESSIMISTIC GIVEN USUAL TENDENCY FOR LOW LEVEL MOISTURE TO BE
SLOWER TO SCOUR THERE AND AT KROA WHERE EAST TO SE FLOW LOOKS TO
HOLD FOR MOST OF THE DAY.
BY THIS EVENING...THE UPPER LOW WILL BEGIN TO OPEN INTO A TROUGH
AND WILL GRADUALLY SHIFT NORTHEAST. AS THIS OCCURS...WINDS WILL
BECOME INCREASINGLY WESTERLY BUT RATHER LIGHT AND COULD GO OVERTOP
THE LINGERING COOL POOL LEAVING LOW CIGS AND FOG IN PLACE OUT EAST.
HOWEVER ANOTHER PASSING SPEED MAX ASSOCIATED WITH THIS SYSTEM MAY
GENERATE ADDED SHRA ESPCLY WEST OF THE BLUE RIDGE INTO TONIGHT
WHERE WILL INCLUDE A VCSH MENTION. OTRW KEEPING CIGS MOSTLY MVFR
WEST TO IFR EAST AS LOW LEVEL MOISTURE WILL BE HARD TO SCOUR AT
NIGHT ESPCLY IF ANY ADDED SHRA DEVELOP AND MOVE EAST.
WILL TRANSITION TO A WEATHER PATTERN MORE TYPICAL OF MID AUGUST BY
TUESDAY...WITH SOUTHERLY FLOW BECOMING REESTABLISHED...AND
RAINFALL TAKING THE FORM OF DIURNALLY DRIVEN SHOWERS AND
THUNDERSTORMS. TOWARD THE END OF THE WEEK...LONG RANGE MODELS
BEGIN TO DISAGREE AS TO THE PLACEMENT OF AN UPPER RIDGE...WITH THE
GFS MODEL KEEPING THE RIDGE OVER THE PLAINS...WHILE THE ECMWF
CALLS FOR THE RIDGE TO BUILD EAST OF THE MISSISSIPPI RIVER.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...DS/JH
NEAR TERM...JH/PH
SHORT TERM...RCS
LONG TERM...DS
AVIATION...JH/MBS/NF
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
634 AM CDT SUN AUG 18 2013
UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND MONDAY
ISSUED AT 350 AM CDT SUN AUG 18 2013
THE MAIN FCST CONCERNS ARE TEMPERATURES AND SMALL PCPN CHANCES.
WV IMAGERY AND RUC ANALYSIS INDICATED UPPER LEVEL RIDGING OVER THE
ROCKIES AND NORTHERN PLAINS...WITH STRONG ZONAL FLOW OVER THE
NORTHERN TIER OF THE U.S. AND CANADA. THE MAIN SHORT-WAVE ENERGY
WAS TRACKING THROUGH SOUTHERN SASK AND MANITOBA. THE WSTRN
PERIPHERY OF A LARGE SFC HIGH PRESSURE SYSTEM WAS STILL SITUATED
OVER WI...WITH STRONG RETURN FLOW SETTING UP IN ADVANCE OF A COLD
FRONT MOVG THROUGH THE DAKOTAS.
HIGH PRESSURE WILL ONCE AGAIN DOMINATE OUR WEATHER TODAY...WITH
UPPER LEVEL ENERGY REMAINING WELL TO OUR NORTH. EXPECT DIURNAL
CUMULUS CLOUDS TO DEVELOP AGAIN TODAY...ALONG WITH AN INCREASE IN
HIGH CLOUDS ACROSS N WI. MIXING THROUGH 825-800 MB SHOULD YIELD
MAX TEMPS IN THE LOWER TO MIDDLE 80S.
A S/W TROF IS EXPECTED TO MOVE INTO NW WI LATE TONIGHT. SOME WAA
WILL ALSO OCCUR OVER NW/NC WI...WITH SOME ELEVATED INSTABILITY
WORKING ITS WAY TOWARD OUR NW COUNTIES BY MORNING. GENERAL MODEL
CONCENSUS IS TO KEEP ANY PCPN JUST NW OF GRB CWA THROUGH 12Z...
SO WILL GO WITH A DRY FCST FOR NOW. THINK THAT FOG WILL LESS OF
THREAT THAN IT HAS BEEN FOR THE PAST SEVERAL NIGHTS...AS THE SFC
PRESSURE GRADIENT TIGHTENS UP AND BOUNDARY LAYER FLOW INCREASES TO
15-20 KTS. TEMPS SHOULD BE A FEW DEGREES WARMER...WITH LOWS IN THE
50S.
ON MONDAY...A S/W TROF WILL MOVE THROUGH NORTHERN WI...PERHAPS
TRIGGERING ISOLD TSTMS WITHIN A WEAK INSTABILITY AXIS OVER NC AND
FAR NE WI. INCREASING SW WINDS SHOULD PULL WARMER TEMPS INTO THE
REGION...BOOSTING HIGHS INTO THE MIDDLE TO UPPER 80S AT MOST
LOCATIONS.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
ISSUED AT 350 AM CDT SUN AUG 18 2013
SUMMER TIME PATTERN EXPECTED THROUGH MUCH OF THE WEEK. THE BIG
STORY WILL BE THE HEAT WITH HIGHS WELL INTO THE 80S AND SOME 90S
TUESDAY AND WEDNESDAY. COLD FRONT IS EXPECTED TO ENTER NORTHWEST
WISCONSIN WEDNESDAY AFTERNOON...PASS ACROSS THE AREA WEDNESDAY
NIGHT AND THEN PUSH SOUTH OF THE AREA ON THURSDAY. WITH THE HEAT
AND HUMIDITY IN PLACE ALONG WITH 0-6 KM SHEAR...THERE IS STILL
SOME POTENTIAL FOR STRONG OR SEVERE STORMS ACROSS THE AREA...WHICH
IS ALREADY IN THE HAZARDOUS WEATHER OUTLOOK.
BEYOND WEDNESDAY NIGHT...IT APPEARS THE GFS/CANADIAN ARE TAKING
THE LEAD IN MODEL TRENDS FOR THURSDAY/THURSDAY NIGHT. THIS IS UNUSUAL
SINCE THE ECMWF USUALLY PERFORMS BETTER IN THE OUTER PERIODS. ON THE
00Z RUN TONIGHT...THE GFS/CANADIAN PUSH THE FRONT FAR ENOUGH SOUTH
OF THE AREA TO ALLOW FOR DRY CONDITIONS LATER THURSDAY MORNING
INTO THURSDAY AFTERNOON. HAVE REMOVED POPS ACROSS THE NORTH ON
THURSDAY AND CONTINUED A SMALL CHANCE ACROSS THE SOUTH. FIGURING
THE SMALL CHANCE WOULD BE FOR ANY LINGERING MORNING CONVECTION.
STILL A LOT OF UNCERTAINTY WHEN CONVECTION WOULD RETURN THURSDAY
NIGHT/FRIDAY OR EVEN FRIDAY NIGHT AMONG THE MODELS. WILL LEAVE
FRIDAY/SATURDAY FORECAST ALONE DUE TO LARGE MODEL UNCERTAINTY.
&&
.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 626 AM CDT SUN AUG 18 2013
PATTERN IS SIMILAR TO THE PAST 4 OR 5 DAYS...WITH A FEW MINOR
DIFFERENCES. HIGH PRESSURE REMAINS OVER THE REGION...ALTHOUGH
THE PRESSURE GRADIENT IS STARTING TO INCREASE TO OUR NORTHWEST
AS A COLD FRONT APPROACHES FROM THE DAKOTAS. THERE IS ALSO AN
INCREASE IN HIGH CLOUDS ARRIVING FROM THE NORTHERN PLAINS.
LINGERING PATCHY FOG WILL DISSIPATE QUICKLY THIS MORNING...WITH
DIURNAL CUMULUS REFORMING BY LATE MORNING...THEN DISSIPATING BY
EARLY EVG. EXPECT FOG TO BE LESS OF A THREAT TONIGHT...AS LOW
LEVEL WINDS GRADUALLY INCREASE. SCT SHRA/ISOLD TSRA MAY MAKE
THEIR WAY INTO NW WI LATE TONIGHT...BUT SHOULD NOT APPROACH THE
RHI TAF SITE UNTIL AFTER 12Z/MON.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....KIECKBUSCH
LONG TERM......ECKBERG
AVIATION.......KIECKBUSCH
AREA FORECAST DISCUSSION
NWS RENO NV
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 DENVER/BOULDER CO
1027 AM MDT SUN AUG 18 2013
.UPDATE...UPPER LEVEL RIDGE WILL BRING ANOTHER VERY WARM DAY TO
THE AREA. THE TAIL END OF A SHORT WAVE TROUGH MOVING ACROSS THE
NORTHERN ROCKIES AND NORTHERN PLAINS WITH PRODUCE SOME LIFT OVER
THE AREA THIS AFTERNOON AND EVENING. AIRMASS IS STILL ON THE DRY
SIDE...BUT MOISTURE HAS INCREASED. THE 12Z SATURDAY SOUNDING AT
GRAND JUNCTION SHOWED 0.40 OF AN INCH WHILE TODAY`S 12Z SOUNDING
SHOWED 0.82. THIS INCREASE IN MOISTURE WILL RESULT MORE CONVECTION
OVER THE MOUNTAINS TODAY. CAPES STILL LESS THAN 500 J/KG ALONG THE
FRONT RANGE AND OVER THE MOUNTAINS. SO ANY CONVECTION THAT FORMS
SHOULD BE HIGH BASED AND WEAK WITH GUSTY OUTFLOW WINDS BEING THE
MAIN CONCERN.
OVER THE EASTERN PLAINS...WHERE LOW LEVEL MOISTURE WILL BE
GREATER. DEW POINTS WILL BE IN THE 50S TO LOWER 60S. THIS WILL
LEAD TO CAPES OF 1000-2000 J/KG. AIRMASS WILL LIKELY BE
CAPPED...ESPECIALLY OVER FAR EASTERN COLORADO AND EASTWARD.
SOUTHEAST WINDS WILL INCREASE THIS AFTERNOON. THESE SOUTHEAST
WINDS COMBINED WITH NORTHWEST WINDS ALOFT MAY PRODUCE ENOUGH
SHEAR FOR A COUPLE OF SEVERE STORMS. THE AREA OF BEST INSTABILITY
AND SHEAR WILL BE EAST OF A LINE FROM FORT MORGAN TO LIMON. WILL
MENTION A SEVERE THREAT IN THE HAZARDOUS WEATHER OUTLOOK. COVERAGE
OF STORMS WILL BE ISOLATED BECAUSE OF A CAP IN PLACE...BUT SHOULD
BE ABLE TO BREAK IN A FEW SPOTS BECAUSE OF THE SHORT WAVE TROUGH
AND CONVERGENCE ALONG OUTFLOW BOUNDARIES.
&&
.AVIATION...LIGHT WINDS THIS MORNING WILL TURN EASTERLY THIS
AFTERNOON. SCATTERED THUNDERSTORMS OVER THE HIGHER TERRAIN WILL
PUSH OUTFLOW WINDS ACROSS THE DENVER LATE THIS AFTERNOON AND MAY
CAUSE WIND TO SHIFT WESTERLY FOR A SHORT TIME. JUST A SLIGHT
CHANCE FOR A THUNDERSTORMS AT THE DENVER AIRPORTS WITH A SLIGHTLY
BETTER CHANCE OVER THE EASTERN PLAINS. VARIABLE WINDS WILL BE
POSSIBLE 21-03Z BECAUSE OF OUTFLOW FROM THUNDERSTORMS. EVENTUALLY
WINDS WILL SETTLE SOUTHERLY BY 06Z.
&&
.PREV DISCUSSION... /ISSUED 357 AM MDT SUN AUG 18 2013/
SHORT TERM...ONCE AGAIN SOME STRATUS AND FOG WERE DEVELOPING OVER
THE NERN PLAINS EARLY THIS MORNING. A WELL DEFINED DENVER CYCLONE
WAS OVER SWRN WELD COUNTY AND WILL LIKELY PULL SOME OF THIS
STRATUS BACK WESTWARD ACROSS MUCH OF WELD COUNTY BY 12Z. APPEARS
THE LOW CLOUDS WILL LINGER THRU THE LATE MORNING HOURS ACROSS THE
NERN PLAINS BEFORE BREAKING UP BY 18Z.
FOR THIS AFTN AN UPPER LEVEL RIDGE WILL BE OVER THE AREA WITH WEAK
MID LVL FLOW. THERE WILL BE AN INCREASE IN SUBTROPICAL MOISTURE
WITH PRECIPITABLE WATER SLOWLY RISING. OVERALL INSTABILITY IS NOT
THAT UNSTABLE ACROSS THE HIGHER TERRAIN AND FRONT RANGE WHERE CAPES
WILL BE BLO 500 J/KG. OVER THE NERN PLAINS CAPES WILL BE BETTER
WITH VALUES RANGING FM 1500-2000 J/KG. WILL SEE SOME HIGH BASED
SHOWER AND TSTM ACTIVITY OVER THE HIGHER TERRAIN WITH OUTFLOW
BOUNDARIES TRIGGERING STRONGER STORMS OVER THE PLAINS WHERE
INSTABILITY WILL BE BETTER. AS FOR HIGHS 850-700 MB TEMPS WOULD
SUPPORT READINGS IN THE LOW TO MID 90S OVER NERN CO WITH A FEW UPPER
90S POSSIBLE ALONG THE FRONT RANGE.
BY TONIGHT TSTM ACTIVITY SHOULD GRADUALLY END IN THE EARLY EVENING
HOURS. MAY SEE SOME REDEVELOP OF STRATUS AND FOG OVER THE NERN
PLAINS AFTER MIDNIGHT.
LONG TERM...MODELS SHOW LITTLE MOVEMENT IN THE STRONG UPPER
LEVEL RIDGE CENTERED JUST EAST OF THE CONTINENTAL DIVIDE ON
MONDAY DURING THE UPCOMING WEEK. ALTHOUGH 500MB HEIGHTS ARE
PROGGED TO GRADUALLY LOWER LATER IN THE WEEK AS THE SWIFT ZONAL
FLOW UP ALONG THE U.S./CANADIAN BORDER DIPS SOUTH AS THE CUTOFF
LOW NOW OFF THE CALIFORNIA COAST FILLS AND EJECTS NEWRD OVER THE
NRN ROCKIES BY FRIDAY. THIS WOULD CAUSE TEMPERATURES LOCALLY TO
MODERATE SOME...GOING FROM ABOVE AVERAGE ON MONDAY-WEDNESDAY TO
BELOW AVERAGE BY THE WEEKEND. A PERSISTENT ALBEIT LIGHT
SOUTHWESTERLY 700-500MB FLOW WILL CONTINUE TO ADVECT MINOR WAVES
OF MOIST UNSTABLE SUBTROPICAL AIR UP OVER WESTERN COLORADO
BENEATH THE UPPER RIDGE DURING THE UPCOMING WEEK. THIS WILL RESULT
IN DAILY ROUNDS OF ISOLATED TO SCATTERED T-STORMS PRIMARILY ALONG
AND WEST OF THE CONTINENTAL DIVIDE. LIGHT STEERING WINDS AND
GRADUALLY HIGHER PRECIPITABLE WATER VALUES MAY RESULT IN LOCALLY
HEAVY RAINFALL FROM THESE SLOW MOVING STORM CELLS. EAST OF THE
MOUNTAINS...ATMOSPHERE APPEARS QUITE DRY AND CAPPED FOR MUCH OF
THE WEEK RESULTING IN LITTLE IF ANY T-STORM DEVELOPMENT. HOWEVER
ON WEDNESDAY...MODELS DO SHOW AN INCREASE IN DEWPOINTS AND PW
VALUES ON THE PLAINS WITH THE PASSAGE OF A WEAK 700-500MB
SHORTWAVE TROUGH. AT PRESENT TIME...DO NOT HAVE ANY T-STORMS IN
THE FCST FOR WEDNESDAY EAST OF THE MTNS WITH QUITE ABIT OF CIN
AROUND. HOWEVER SHOULD THE MODELS CONTINUE TO INDICATE THIS
INCREASE IN LOW/MID-LEVEL MOISTURE WITH EACH RUN...WILL PROBABLY
NEED TO ADD AT LEAST A SLIGHT CHANCE OF AFTERNOON/EVENING STORMS
FOR THE PLAINS WEDNESDAY AFTERNOON AND EVENING.
AVIATION...DENVER CYCLONE WAS OVER SWRN WELD COUNTY AND IS FCST
TO STAY OVER SRN WELD THIS MORNING. LATEST HRRR KEEPS THE STRATUS
AND FOG TO THE NORTH AND NE OF DIA AS SFC WINDS STAY WSW SO WILL
KEEP OUT OF THE TAF. BY EARLY AFTN WINDS WILL BECOME LIGHT ENE
HOWEVER OUTFLOW BOUNDARIES FM HIGH BASED CONVECTION OVER THE
FOOTHILLS MAY TRACK ACROSS IN THE 21Z-23Z TIME FRAME WITH WINDS
SHIFTING TO THE NW WITH SPEEDS IN THE 10-20 MPH RANGE. AT THIS
TIME LOOKS LIKE TSTMS WILL STAY MOSTLY TO EAST SO WILL ONLY
MENTION VCTS. BY THIS EARLY THIS EVENING WINDS WILL BECOME WSW AND
THEN SSW BY 06Z.
HYDROLOGY...WIDELY SCATTERED THUNDERSTORMS WILL DEVELOP THIS
AFTERNOON HOWEVER RAINFALL AMOUNTS SHOULD BE UNDER ONE QUARTER
INCH IF THEY MOVE OVER THE BURN AREAS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....BAKER
UPDATE/AVIATION...MEIER
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
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/...
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...
18Z UPDATE...
CHALLENGING FORECAST CYCLE AS WE DEAL WITH COOL HIGH PRESSURE FOR
NORTHERN TAF SITES AND STATIONARY FRONT FOR THE SOUTHERN MOST
SITES. THIS HAS RESULTED IN SITES FROM ATL SOUTHWARD BECOMING MVFR
THIS AFTERNOON WITH EVEN SOME VFR FOR CSG. EXPECT SITES NORTH OF
ATL TO REMAIN A THOUSAND FEET OR LESS THROUGH THE REMAINDER OF THE
EVENING. ALL SITES WILL GO IFR BY LATE THIS EVENING AND THEN LIFR
FOR THE EARLY MORNING HOURS. SHRA LOOK TO REDEVELOP BY THIS
EVENING AS WELL AND HAVE INCLUDED TEMPO THROUGH 02Z FOR ALL SITES.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM ON ALL ELEMENTS
DEESE
&&
.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...DEESE
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
156 PM EDT SUN AUG 18 2013
.PREV DISCUSSION... /ISSUED 1005 AM EDT SUN AUG 18 2013/
UPDATE...MODELS DEPICT SHORTWAVE IN MEAN FLOW MOVING FROM THE
GULF COAST UP THE WESTERN SIDE OF THE STATE. THIS HAS ALLOWED
FOCUS FOR RAINFALL TO SHIFT FROM THE SOUTHERN PORTIONS AS HAS BEEN
THE CASE THE PAST FEW DAYS TO MAINLY NORTHWEST GEORGIA THIS
MORNING. PROBLEMATIC FORECAST FOR THE REMAINDER OF TODAY WITH
SHORTWAVE CONTINUING TO EXERT INFLUENCE BUT ALSO MAJOR
CONTRIBUTING FACTORS FROM WEDGE AND HOW IT ERODES IF ANY AND
STATIONARY FRONT TO THE SOUTH AND HOW MUCH IT LIFTS NORTH IF ANY.
WILL LEAN TOWARD THE GFS WHICH HAS AN UNUSUAL SOLUTION OF A
STRONGER WEDGE THAN THE NAM12. THIS WILL KEEP FRONT TO THE SOUTH
AND WEDGE IN PLACE ALTHOUGH NOT QUITE AS STRONG AS YESTERDAY AS
EVIDENCED BY ATLANTAS TEMP OF 70 ALREADY. SHOULD SEE WAVES OF
PRECIP REDEVELOP WITH WESTERN SIDE REMAINING FAVORED. OTHER THAN
ELEVATED CONVECTION...FEEL THERE IS STILL AN OPPORTUNITY FOR SOME
SURFACE BASED ACTIVITY OVER THE EXTREME SOUTH LATE WHERE HRRR AND
WRF INDICATE MORE PRONOUNCED ACTIVITY. SHEAR IS MARGINAL BUT IN
VICINITY OF FRONT WILL NEED TO WATCH CLOSELY FOR ANY POTENTIAL
ROTATION IN STRONGER CELLS. OTHERWISE...FLOOD WATCH AND REMAINING
GRIDS LOOK ON TARGET AND NO CHANGES PLANNED.
PREV DISCUSSION... /ISSUED 734 AM EDT SUN AUG 18 2013/
SHORT TERM /TODAY THROUGH MONDAY/...
/ISSUED AT 445 AM EDT SUN AUG 18 2013/
LATEST SURFACE ANALYSIS SHOWS A WARM FRONT JUST SOUTH OF COLUMBUS
AND AUGUSTA...BUT JUST NORTH OF MACON. NAM AND ECMWF DRIFT THE FRONT
NORTHWARD AT LEAST INTO WEST CENTRAL GA THIS AFTERNOON AS THE UPPER
LOW CURRENTLY OVER WEST KY/TN BEGINS TO KICK EASTWARD LATER THIS
AFTERNOON. THE GFS HOLDS THE COOL WEDGE OVER THE NORTHEAST AND EAST
CENTRAL ZONES THROUGH TONIGHT...WHICH WILL MAKE TEMPS TRICKY TODAY.
SURFACE ANALYSIS ALSO SHOWS AN AREA OF LOW PRESSURE ALONG THE LA
COAST WHERE IT APPEARS TO BE DRIFTING NORTHWARD. NAM AND ECMWF DRIFT
THE SURFACE LOW WNW TODAY WHILE THE GFS DRIFTS IT NNE INTO SE LA.
THE GFS SEEMS TO INITIALIZE SLIGHTLY BETTER WITH THIS FEATURE AND
WITH THE UPPER LOW TO THE NORTH...WOULD NOT BE SURPRISED TO SEE THIS
SURFACE LOW DRIFT NNE AS THE GFS SUGGEST. THIS WOULD ALLOW THE WARM
FRONT TO ALSO DRIFT NORTH...AT LEAST INTO THE WEST CENTRAL ZONES
MAYBE FROM NEAR AUGUSTA TO ATLANTA TO ROME AS THE WEDGE MAY HOLD
STRONG FOR AREAS NE OF THIS LINE. EITHER WAY... MODELS SUGGEST THE
FRONT COULD PROVIDE A FOCUS FOR PERIODS OF HEAVY RAIN ACROSS THE NW
AND WEST CENTRAL ZONES TODAY...WHERE 1 TO 2 INCHES WITH ISOLATED
HIGHER AMOUNTS MAY BE POSSIBLY THROUGH 8 PM THIS EVENING AS THE
UPPER LOW BEGINS TO LIFT TO THE ENE. DECIDED TO PLAY IT SAFE AND
POST A FLASH FLOOD WATCH FOR THE WESTERN ZONES THROUGH 8 PM THIS
EVENING...GENERALLY FOR AREAS ALONG AND WEST OF A BLUE RIDGE TO
ATLANTA TO MACON LINE. THE WEDGE MAY HOLD STRONG ENOUGH TO THE EAST
TO ONLY ALLOW OCCASIONAL LIGHT TO MODERATE RAINS. WITH MUCH
UNCERTAINTY ON THE PROGRESSION OF THE WARM FRONT TODAY...
TEMPERATURES WILL BE VERY TRICKY. DECIDED TO TAKE A BLEND BETWEEN
THE WARMER MET AND COOLER MAV NUMBERS...WITH A LEAN TOWARD THE
COOLER GFS OVER THE EASTERN ZONES WHERE THE WEDGE WILL LIKELY
PERSIST. WILL ALSO WORD FOR ISOLATED THUNDERSTORMS ACROSS THE ENTIRE
FORECAST AREA THIS AFTERNOON AS THE UPPER LOW INTERACTS WITH
INCREASING INSTABILITIES ALONG AND SOUTH OF THE WARM FRONT. EXPECT
THE WEDGE INFLUENCE TO WEAKEN EVEN MORE ON MONDAY AS THE UPPER LOW
SHEARS OFF TO THE NE TONIGHT...LEAVING AN ACTIVE WEAK TROUGH IN ITS
PLACE. THIS COUPLED WITH HIGH PRESSURE OFF THE MID ATLANTIC COAST
WILL STILL PROVIDE FOR AN ESE WIND FLOW TONIGHT AND ON MONDAY. SO
DESPITE A WARMING TREND...STILL EXPECT WELL BELOW NORMAL HIGHS ON
MONDAY FOR MOST AREAS. A DEEPER SE WIND FLOW AND INCREASING
INSTABILITIES NORTHWARD WILL WARRANT A CHANCE OF THUNDERSTORMS ALL
ZONES FOR MONDAY AFTERNOON.
39
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
/ISSUED AT 445 AM EDT SUN AUG 18 2013/
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
HYDROLOGY...
/ISSUED AT 445 AM EDT SUN AUG 18 2013/
AN UPPER LOW PRESSURE SYSTEM TO THE NORTHWEST WILL INTERACT WITH A A
WARM FRONT DRIFTING NORTH TODAY TO PRODUCE A CHANCE OF HEAVY RAIN
ACROSS MAINLY NORTHWEST AND WEST CENTRAL GA TODAY. MODEL AND HPC QPF
NUMBERS SUGGEST ANYWHERE FROM 1 TO 2 INCHES WITH ISOLATED HIGHER
AMOUNTS IS POSSIBLE THROUGH THE AFTERNOON AND EVENING HOURS TODAY.
THEREFORE... HAVE POSTED A FLASH FLOOD WATCH THROUGH 8 PM THIS
EVENING FOR AREAS ALONG AND WEST OF A BLUE RIDGE TO ATLANTA TO MACON
LINE WHERE THE GREATEST RAINFALL AMOUNTS ARE EXPECTED. HOWEVER...
STILL MUCH UNCERTAINTY ON LOCATION...INTENSITY AND DURATION OF
CONVECTION THROUGH THE AFTERNOON AND EVENING HOURS...SO SOME AREAS
EAST OF THE WATCH COULD STILL SEE PERIODS OF BRIEF HEAVY RAIN. /39
CLIMATE...
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
&&
.AVIATION...
18Z UPDATE...
CHALLENGING FORECAST CYCLE AS WE DEAL WITH COOL HIGH PRESSURE FOR
NORTHERN TAF SITES AND STATIONARY FRONT FOR THE SOUTHERN MOST
SITES. THIS HAS RESULTED IN SITES FROM ATL SOUTHWARD BECOMING MVFR
THIS AFTERNOON WITH EVEN SOME VFR FOR CSG. EXPECT SITES NORTH OF
ATL TO REMAIN A THOUSAND FEET OR LESS THROUGH THE REMAINDER OF THE
EVENING. ALL SITES WILL GO IFR BY LATE THIS EVENING AND THEN LIFR
FOR THE EARLY MORNING HOURS. SHRA LOOK TO REDEVELOP BY THIS
EVENING AS WELL AND HAVE INCLUDED TEPO THROUGH 02Z FOR ALL SITES.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM ON LL ELEMENTS
DEESE
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 75 69 81 70 / 50 50 50 50
ATLANTA 74 68 79 71 / 70 70 50 40
BLAIRSVILLE 69 65 77 65 / 70 70 50 50
CARTERSVILLE 74 68 80 70 / 80 70 50 50
COLUMBUS 75 71 82 72 / 100 60 50 40
GAINESVILLE 72 68 78 69 / 60 70 50 50
MACON 76 71 83 71 / 50 40 50 40
ROME 72 68 81 70 / 90 80 40 50
PEACHTREE CITY 74 67 80 70 / 80 60 50 40
VIDALIA 82 72 86 72 / 60 50 50 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...DEESE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
411 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 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 127 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. THERE ARE A COUPLE
OF ITEMS OF NOTE. FIRST...INCREASING SW WINDS ABOVE NOCTURNAL
INVERSION TONIGHT WILL APPROACH LLWS CRITERIA. SECOND...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...AND IF THERE IS ANY
CONVECTION...CONFIDENCE IS EVEN LOWER ON 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...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
128 PM EDT SUN AUG 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 344 AM EDT SUN AUG 18 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW UPR RDG STRETCHING
FM THE NCENTRAL PLAINS INTO THE UPR LKS TO THE S OF ZONAL FLOW OVER
SRN CANADA AND N OF CLOSED LO IN THE MID MS RIVER VALLEY. THE CWA IS
DOMINATED BY THE SW LLVL FLOW ON THE WRN FLANK OF SFC HI PRES OVER
THE NE CONUS. LOCAL 00Z RAOBS DEPICT SHARP SUBSIDENCE INVRN BTWN
H75-85 WITH DRY MID LVLS UNDER THE UPR RDG AXIS. THERE IS A SHRTWV
TRACKING EWD WITHIN THE ZONAL FLOW AND OVER A STNRY FNT IN
ONTARIO...BUT ONLY SOME HI CLDS ON THE SRN EDGE OF THIS DISTURBANCE
ARE SPILLING INTO LK SUP. THE SW FLOW ARND THE SFC HI TO THE E IS
TAPPING FAIRLY DRY LLVL AIR SHOWN ON THE 00Z MPX/GRB RAOBS...WHERE
THE H85 DEWPT WAS 7C AT BOTH SITES. MORE HUMID AIR IS PRESENT OVER
THE CENTRAL HI PLAINS...WHERE THE 00Z H85 DEWPT WAS 16C AT NORTH
PLATTE NEBRASKA.
MAIN FCST CONCERNS IN THE SHORT TERM WL BE TEMPS WITH SPRAWLING RDG
DOMINATING. LATER TNGT...FOCUS SHIFTS TO WHETHER THERE MIGHT BE A
FEW SHRA/TS OVER THE FAR WRN CWA AS SHRTWV EMBEDDED IN ZONAL FLOW
ALF TAPS SOME OF THE MORE HUMID H85 AIR IN THE CENTRAL HI PLAINS.
TDAY...WITH UPR RDG/SUBSIDENCE INVRN/MID LVL DRY AIR LINGERING OVER
UPR MI...EXPECT ANOTHER DRY DAY FOR UPR MI WITH NOTHING MORE THAN
SOME DIURNAL CU. H85 TEMPS ARE FCST TO BE 14-15C BY 00Z MON...UP TO
1C HIER THAN AT 00Z SUN. MIXING TO H8 AS OBSVD YDAY YIELDS HI TEMPS
80-85 AWAY FM THE MODERATING INFLUENCE OF LK MI IN CONTINUED LLVL SW
FLOW. THE DEEP MIXING MIGHT ALLOW FOR SOME GUSTS UP TO 20 MPH OVER
MAINLY THE NW CWA WHERE THE PRES GRADIENT WL BE A BIT TIGHTER/H925
WIND UP TO 20-25KTS. WITH MIN RH DROPPING TO ARND 35 PCT AS DEWPTS
MIX OUT DOWN TO THE LO 50S AND RECENT DRYNESS...FIRE WX CONCERNS WL
BE A BIT ELEVATED IN THAT AREA.
TNGT...MODELS REMAIN CONSISTENT SHOWING SHRTWV EMBEDDED IN ZONAL
FLOW OVER SRN SASKATCHEWAN SHIFTING ESEWD TOWARD THE UPR LKS AND
WEAKENING THE UPR RDG...WITH 00Z-12Z MON H5 HGT FALLS UP TO 40M OVER
THE CWA. AT THE SAME TIME...PERSISTENT SW FLOW IS PROGGED TO TAP
SOMEWHAT MORE HUMID H85 AIR NOW SHOWING UP IN THE CENTRAL PLAINS...
WITH FAIRLY VIGOROUS H85 THETA E ADVECTION INTO THE WRN CWA AFT 06Z.
THE MAIN PROBLEM FOR SHRA/TS DVLPMNT IS THE VERY DRY/STABLE
ANTECEDENT AIRMASS. IN FACT...NAM/GFS FCST SDNGS SHOW THE PROFILE
REMAINING TOO STABLE FOR CONVECTION EVEN OVER THE W EXCEPT PERHAPS
AT IWD TOWARD 12Z. ALTHOUGH THE BULK OF ANY SHRA/TS WL LIKELY BE TO
THE NW TOWARD LOWER HGTS/STNRY FNT IN ONTARIO...OPTED TO RETAIN
GOING SCHC POPS REACHING THE WRN LAND CWA IN THE 09Z-12Z TIME GIVEN
THE ARRIVAL OF THE HIER H85 THETA E...SSI FALLING TO NEAR -2C AND
AXIS OF H85-5 QVECTOR CNVGC FCST TO REACH THIS AREA IN THE 06Z-12Z
TIME. COMBINATION OF INCRSG PWAT TOWARD 1.5 INCH LATE OVER THE W AND
STEADY WSW H925 FLOW WITH WINDS UP TO 25-30KTS WL HOLD MIN TEMPS UP
OVER THE NW IN THE DOWNSLOPE AREAS NEAR LK SUP. BEST CHC FOR SOME
MINS IN THE COOLER 50S WL BE OVER THE INTERIOR SCENTRAL AND E...
WHERE WINDS WL BE LIGHTER AND DRIER AIR WL LINGER LONGEST.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 344 AM EDT SUN AUG 18 2013
MOST ATTENTION IN THE LONG TERM WAS FOCUSED ON TEMPS /MAINLY
THROUGH MID WEEK/ AND PRECIP /MAINLY WED INTO WED NIGHT/ WITH A COLD
FRONT MOVING INTO THE CWA.
LARGE SCALE WISE...AT 12Z MON...THERE WILL BE UPPER LEVEL HIGH
PRESSURE OVER MUCH OF THE CONUS...WITH ZONAL FLOW OVER CANADA. AT
THE SFC...THE CWA WILL BE BETWEEN HIGH PRESSURE COVERING MOST OF THE
CONUS AND A TROUGH OVER SASKATCHEWAN/MANITOBA. A SHORTWAVE WILL BE
OVER THE FAR WRN CWA AT 12Z MON...AND WILL TO THE CENTRAL CWA BY 18Z
MON. PRECIP WITH THE SHORTWAVE IS UNCERTAIN...BUT WILL CONTINUE TO
FAVOR LESSER PRECIP SOLUTIONS DUE TO THE SHORTWAVE PASSING BEFORE
PEAK HEATING AND THAT IT WILL BE PUSHING INTO HIGH PRESSURE.
STILL...MAY BE SOME ISOLATED SHOWERS/THUNDERSTORMS THAT TRY TO POP
UP. HIGHS WILL BE IN THE UPPER 70S TO MID 80S ON MON AS 850MB TEMPS
INCREASE TO AROUND 15C.
THE ZONAL FLOW WILL CONTINUE TO PUSH DYING PIECES OF ENERGY INTO THE
CWA TUE...BUT SAME STORY AS MON WITH THE SHORTWAVE PUSHING INTO THE
HIGH PRESSURE. BY 18Z TUE...850MB TEMPS WILL BE AROUND 18C...SO
HIGHS WILL BE EVEN WARMER IN THE 80S TO AROUND 90.
THE BIGGER QUESTION FOR THE FORECAST COMES ON WED AS A SFC
TROUGH/COLD FRONT MOVES INTO THE CWA LATER IN THE DAY INTO THE EARLY
OVERNIGHT HOURS WED NIGHT. GIVEN FORCING COMBINED WITH INSTABILITY
/CAPE VALUES AROUND 1500-2500 J/KG/ SHOULD LEAD TO SHOWERS AND
THUNDERSTORMS MOVING INTO/DEVELOPING ACROSS THE CWA. INCREASED POPS
SOME AS CONFIDENCE CONTINUES TO IMPROVE. WITH THE INSTABILITY AND
0-6KM BULK SHEAR AROUND 20KTS...A SEVERE STORM OR TWO CANNOT BE
RULED OUT...BUT IT IS STILL PRETTY EARLY FOR THAT DETERMINATION.
HIGHS ON WED LOOK TO BE SIMILAR TO TUESDAY.
POST COLD FROPA...THURSDAY IS THE MOST PREDICTABLE DAY AS COOLER
850MB TEMPS AROUND 14C WILL BE OVER THE CWA. THIS SHOULD RESULT IN
HIGHS IN THE 70S TO AROUND 80 /WARMEST SCENTRAL/. CONFIDENCE
DECREASES SIGNIFICANTLY AFTER THURSDAY AS MODELS SHOW WIDELY
DIFFERENT SOLUTIONS...MAINLY FOR TEMPS. THE ECMWF BRINGS A STRONG
UPPER RIDGE OVER THE REGION FRI INTO SAT...WHICH WOULD RESULT IN
VERY WARM TEMPS AGAIN. THE GFS KEEP THE STRONGEST PART OF THAT RIDGE
WELL TO OUR W...SO TEMPS ARE NOT AS WARM. WILL JUST GO WITH A
CONSENSUS OF MODEL GUIDANCE AT THIS TIME AND FOCUS ON SHORTER TERM
ISSUES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 127 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. THERE ARE A COUPLE
OF ITEMS OF NOTE. FIRST...INCREASING SW WINDS ABOVE NOCTURNAL
INVERSION TONIGHT WILL APPROACH LLWS CRITERIA. SECOND...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...AND IF THERE IS ANY
CONVECTION...CONFIDENCE IS EVEN LOWER ON LOCATION/COVERAGE. THUS...
NO MENTION OF SHRA/TSRA WAS INCLUDED IN THIS FCST ISSUANCE.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 344 AM 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 WINDS UP TO 20-25 KTS MAY
IMPACT THE W AND NCENTRAL TONIGHT UNDER A SHARPER PRES GRADIENT
AHEAD OF AN APPROACHING DISTURBANCE. THE ARRIVAL OF MORE HUMID AIR
FOR TUE/WED WILL RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE
WATERS. ANY FOG WILL DISSIPATE ON 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...TITUS
LONG TERM...KC
AVIATION...ROLFSON
MARINE...KC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
116 PM CDT SUN AUG 18 2013
.UPDATE...
ISSUED AT 116 PM CDT SUN AUG 18 2013
A SHORTWAVE OVER NORTHEASTERN MONTANA CONTINUES TO GENERATE
ELEVATED SHOWERS WITH ISOLATED THUNDERSTORMS OVER WESTERN NORTH
DAKOTA. THIS WAVE IS STILL PROGGED TO MOVE INTO WESTERN AND
CENTRAL NORTH DAKOTA LATER THIS AFTERNOON.
AT THE SURFACE...DEWPOINTS ARE IN THE UPPER 60S OVER SOUTH CENTRAL
AND SOUTHEASTERN NORTH DAKOTA. LAPS IS ANALYZING SURFACE-BASED
CAPE AROUND 3800 J/KG OVER SOUTH CENTRAL NORTH DAKOTA AS A RESULT.
HOWEVER...IT IS ALSO ANALYZING CIN OF 180 J/KG...WHICH IS QUITE A
HURDLE TO OVERCOME. NEVERTHELESS...SOME CLEARING IS NOTED WEST OF
A LINE FROM MINOT TO DICKINSON TO BOWMAN. ASSUMING THE RELATIVE CLEARING
LINE MAINTAINS ITS CURRENT DIRECTION AND SPEED...THE AREA FROM
BISMARCK TO JAMESTOWN SOUTH SHOULD CLEAR OUT BETWEEN 21Z-24Z
ALLOWING FOR RAPID HEATING DURING THE LATE AFTERNOON. THIS MAY
PRODUCE ENOUGH DIABATIC FORCING TO OVERCOME THE CAP. ANY STORMS
THAT DO DEVELOP SHOULD RAPIDLY BECOME SEVERE. HOWEVER...THERE IS
STILL SOME UNCERTAINTY AS TO WHETHER STORMS WILL DEVELOP IN THE
FIRST PLACE. THEREFORE MAINTAINED THE LOW-END CHANCE POPS.
AS A RESULT...NOT TOO MANY CHANGES WERE MADE TO THE ONGOING
FORECAST. THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 1025 AM CDT SUN AUG 18 2013
A RATHER COMPLEX WEATHER PATTERN IS SETTING UP OVER WESTERN AND
CENTRAL NORTH DAKOTA TODAY. A SHORTWAVE OVER SOUTHERN MANITOBA HAS
FINALLY GENERATED ENOUGH LIFT FOR THE CAP TO BREAK SOUTH OF LAKE WINNIPEG.
A LINE OF THUNDERSTORMS HAVE DEVELOPED NEAR WINNIPEG ALONG A STALLED
SURFACE BOUNDARY EXTENDING INTO WESTERN AND CENTRAL NORTH DAKOTA.
DO NOT ANTICIPATED THUNDERSTORMS TO DEVELOP SOUTHWESTWARD ALONG
THIS BOUNDARY AS THE CAP (PER 12Z SOUNDING) APPEARS RATHER STRONG
OVER NORTH DAKOTA TODAY.
HOWEVER...A SECOND SHORTWAVE MOVING ACROSS MONTANA IS GENERATING
ELEVATED CONVECTION OVER EASTERN MONTANA INTO NORTHWESTERN SOUTH
DAKOTA. THIS WAVE WILL CONTINUE TO PUSH EAST OVER WESTERN AND
CENTRAL NORTH DAKOTA TODAY. THUNDERSTORMS SHOULD REMAIN ELEVATED
WEST THROUGH THE EARLY AFTERNOON. HOWEVER...AS THE WAVE MOVES INTO
CENTRAL NORTH DAKOTA LATER THIS AFTERNOON...THE CAP IS PROGGED TO
BEGIN TO ERODE AND THUNDERSTORMS COULD BECOME ROOTED IN THE
BOUNDARY LAYER ALONG THE AFOREMENTIONED STALLED FRONT. GIVEN THE
DEEPER CONVECTION POTENTIAL COMBINED WITH MUCAPE VALUES AROUND
2000 J/KG AND DEEP LAYER SHEAR BETWEEN 30-35 KNOTS...THINK THE
SEVERE THREAT WILL DEVELOP PRIMARILY OVER SOUTH CENTRAL AND
SOUTHEASTERN NORTH DAKOTA BETWEEN 22Z-03Z.
UPDATED THE FORECAST TO SPEED UP THE ONSET OF ELEVATED
THUNDERSTORMS WEST THIS MORNING BASED ON RADAR TRENDS. ALSO
REFOCUSED THE TIMING OF SEVERE THUNDERSTORM POTENTIAL TO LATER
THIS AFTERNOON/EVENING. THE UPDATED PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN CONCERN IN THE NEAR TERM WILL BE THE CHANCES OF
THUNDERSTORMS...INCLUDING THE POSSIBILITY OF SEVERE WEATHER.
EARLY MORNING WATER VAPOR IMAGERY SHOWED A WAVE MOVING ACROSS
SOUTHERN PARTS OF SASKATCHEWAN / MANITOBA...WITH ANOTHER WAVE IN
NORTHWEST MONTANA. CONVECTION WITH THE CANADIAN WAVE HAS BEEN
SPARSE...AND THE LATEST NAM / RAP KEEPS THE FORECAST AREA DRY
EARLY THIS MORNING AS THE WAVE PASSES. THE BIGGER CONCERN WILL BE
THE MONTANA WAVE AS IT INTERACTS WITH A WEAK BOUNDARY MOVING
THROUGH THE REGION. A FEW SHOWERS / THUNDERSTORMS ARE POSSIBLE IN
WESTERN NORTH DAKOTA LATER SUNDAY MORNING AS THE WAVE
APPROACHES...BUT DO NOT EXPECT THOSE TO BE SEVERE.
THE SEVERE THREAT IS EXPECTED TO INCREASE THIS AFTERNOON AND
EVENING AS THE MONTANA WAVE HELPS INITIATE THUNDERSTORMS ALONG THE
SLOW MOVING BOUNDARY. THAT BEING SAID...THE CAP REMAINS A
POTENTIAL LIMITING FACTOR DUE TO WARM H7 TEMPERATURES. THE NAM
AND GFS DISAGREE IN REGARDS TO HOW FAST THE MID LEVELS COOL
TODAY...WITH THE NAM BEING MORE AGGRESSIVE. THE NAM WAS ALSO
QUICKER TO INITIATE CONVECTION ALONG THE BOUNDARY ON
SATURDAY...AND AFTER SEEING THE LACK OF DEVELOPMENT ACROSS NORTH
DAKOTA...CONFIDENCE IN HOW WIDESPREAD THE CONVECTIVE DEVELOPMENT
WILL BE IS NOT HIGH. WILL CARRY CHANCE POPS NEAR THE BOUNDARY
TOWARDS LATE AFTERNOON / EARLY EVENING...AND LET LATER SHIFTS
MONITOR TRENDS WITH THE CAP AND POTENTIAL DEVELOPMENT.
IN REGARDS TO THE SEVERE WEATHER THREAT...EXPECT THE MAIN THREAT
AREA TO BE FROM THE SOUTH CENTRAL PART OF THE STATE AND TOWARDS
THE JAMES RIVER VALLEY. THE PRIMARY HAZARD SHOULD BE DAMAGING
WINDS WITH INVERTED V SOUNDINGS...WHILE WARM MID LEVEL
TEMPERATURES COULD LIMIT THE HAIL THREAT TO SOME DEGREE. ELEVATED
LIFTED CONDENSATION LEVELS SHOULD ALSO LIMIT THE TORNADO
POTENTIAL. THE THUNDERSTORM CHANCES ARE EXPECTED TO DIMINISH FROM
WEST TO EAST AS THE WAVE PASSES...WITH DRY WEATHER EXPECTED AGAIN
BY LATE TONIGHT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN HIGHLIGHTS IN THE EXTENDED WILL BE HOT TEMPERATURES
MONDAY AND TUESDAY...WELL INTO 90S...WITH NEAR RECORD HIGHS FOR
BISMARCK TUESDAY. THIS MAY LEAD TO A POSSIBLE HEAT ADVISORY
TUESDAY AFTERNOON ACROSS PORTIONS OF SOUTH CENTRAL NORTH DAKOTA. A
STRONG COLD FRONT WILL FOLLOW FOR TUESDAY NIGHT SUPPRESSING HIGHS
BACK INTO THE 80S FOR THE REST OF THE WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE PATTERN BECOMES MORE ACTIVE
WITH PERIODIC SHOWERS AND THUNDERSTORMS AS A PACIFIC LOW/TROUGH
EJECTS SEVERAL SHORTWAVES VIA A PERSISTENT FETCH OF SOUTHWEST FLOW
ALOFT STRAIGHT INTO NORTH DAKOTA.
FOR MONDAY AND TUESDAY...BEHIND A DEPARTING SHORTWAVE MONDAY MORNING
WILL BE BROAD RIDGING TAKING CONTROL. A LACK OF SHORTWAVE ACTIVITY
MONDAY WITH H85 TEMPS CLIMBING TO AROUND +26C TO +28C...BOTH MONDAY
AND TUESDAY...WILL MAKE THESE THE TWO HOTTEST DAYS IN THE EXTENDED.
PERHAPS A BIT WARMER TUESDAY. LOOKING AT RECORD HIGHS AT THE MAJOR
CITIES MONDAY AND TUESDAY...IT WOULD APPEAR THAT ONLY BISMARCK
WOULD COME CLOSEST TO POSSIBLY TYING A RECORD TUESDAY. THE RECORD IS
100 DEGREES SET BACK IN 1976. WE WILL BE CLOSE TO THAT WITH 98F AS A
FORECAST HIGH TEMPERATURE. WITH MANY SCHOOLS STARTING THIS
WEEK...HAVE TO REALLY CONSIDER THE HEAT IN THE AFTERNOON AS THE HEAT
INDICES WILL BE VERY CLOSE TO 100 DEGREES. WILL HIGHLIGHT THIS IN THE
HAZARDOUS WEATHER OUTLOOK FOR NOW AND BRIEF THE ONCOMING SHIFT THAT
AN ADVISORY MAY BECOME NECESSARY. GFS SOUNDINGS SHOW THAT ENOUGH OF
A CAP REMAINS IN PLACE THROUGH 00Z WEDNESDAY TO INHIBIT CONVECTION.
HAVE DISCOUNTED THE NAM SOLUTION WHICH GENERATES PRECIPITATION EARLY
IN THE DAY...WHILE THE OTHER MODELS KEEP IT DRY DURING THE DAYLIGHT
HOURS.
TUESDAY NIGHT/WEDNESDAY MORNING...A STRONG COLD FRONT WILL PUSH FROM
NORTHWEST TO SOUTHEAST. EXPECT A CHANCE FOR SHOWERS/THUNDERSTORMS
WITH THIS FRONT. H85 TEMPERATURES TAKE A DIGGER WITH +17C IN THE
NORTH WEDNESDAY AFTERNOON TO +20 IN THE SOUTHWEST. SHOULD BE
REFRESHING WITH HIGHS AROUND 80F NORTH TO MID 80S SOUTHWEST. THE
THREAT FOR AN ISOLATED SHOWER/THUNDERSTORM WILL LINGER IN THE SOUTH
THROUGH THE DAY WEDNESDAY.
THURSDAY THROUGH SUNDAY...SOUTHWEST FLOW ALOFT OPENS THE WAY FOR
SEVERAL SHORTWAVE TROUGHS TO MIGRATE THROUGH. UPPER RIDGE WILL BE
DOMINATE IN THE CENTRAL CONUS. THE TIMING OF THE AFOREMENTIONED
SHORTWAVES WILL CHANGE BETWEEN NOW AND LATER IN THE WEEK...BUT THE
HIGHER END CHANCES FOR SHOWERS/THUNDERSTORMS BEGIN TO INCREASE
THURSDAY AND CONTINUE INTO THE WEEKEND. THE ALLBLEND CAPTURES THIS
TREND WELL AND WILL MAINTAIN THAT. THE ECMWF IS A BIT MORE
AGGRESSIVE WITH THE SUCCESSIVE WAVES AND LARGER PRECIPITATION AREAS
VERSUS THE GFS...BUT THE OVERALL PATTERN IN BOTH MODELS IS SIMILAR.
HIGHS WILL REMAIN IN THE 80S WITH LOWS IN THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 116 PM CDT SUN AUG 18 2013
VFR CONDITIONS ARE EXPECTED OVER WESTERN AND CENTRAL NORTH DAKOTA
THROUGH THE TAF PERIOD. LIGHT SHOWERS WITH ISOLATED THUNDERSTORMS
WILL GRADUALLY SPREAD EAST OVER WESTERN AND CENTRAL NORTH DAKOTA
THIS AFTERNOON AND EVENING. HOWEVER...SCATTERED COVERAGE IS
EXPECTED SO ONLY INDICATED VCTS IN THE AFFECTED TAF SITES. AFTER
THIS EVENING...VFR CONDITIONS AND LIGHT/VARIABLE WINDS ARE
EXPECTED OVER WESTERN AND CENTRAL NORTH DAKOTA THROUGH THE
REMAINDER OF THE TAF PERIOD.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...CK
LONG TERM...KS
AVIATION...AC
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
654 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 OVER THE SOUTHERN SCIOTO VALLEY WILL MOVE NORTH AND AFFECT
CMH/LCK TAF SITES LATER THIS AFTERNOON FOR A BRIEF PERIOD.
ATTM...COVERED THIS WITH VICINITY SHOWER AND NO RESTRICTION TO
VSBY BUT IF THEY HOLD TOGETHER WILL AMEND TO BRING INTO MVFR VSBY
DURING A TEMPO GROUP. THIS IS THE ONLY AREA WITH MVFR CIGS AS WELL
TODAY.
WITH THE LOSS OF DAYTIME HEATING...ANY SHOWERS WILL QUICKLY
DIMINISH THIS EVENING AND CU FIELD OVER REMAINING TAF SITES WILL
ALSO DISSIPATE. WHILE THE AXIS OF THE UPPER LOW IS STILL ALONG AND
SSW OF THE REGION...THE ENERGY THAT IS SPARKING THE RAIN IN THE
SOUTHEAST WILL BE TRANSLATING EAST THROUGH PA TONIGHT.
IF THE CLEARING AND LIGHT WINDS ARE REALIZED...SOME DAYBREAK FOG
WITH GENERALLY MVFR VSBYS WILL OCCUR.
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...FRANKS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
426 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/...
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 /20Z SUNDAY THROUGH FRIDAY/...
SHOWERS OVER THE SOUTHERN SCIOTO VALLEY WILL MOVE NORTH AND AFFECT
CMH/LCK TAF SITES LATER THIS AFTERNOON FOR A BRIEF PERIOD.
ATTM...COVERED THIS WITH VICINITY SHOWER AND NO RESTRICTION TO
VSBY BUT IF THEY HOLD TOGETHER WILL AMEND TO BRING INTO MVFR VSBY
DURING A TEMPO GROUP. THIS IS THE ONLY AREA WITH MVFR CIGS AS WELL
TODAY.
WITH THE LOSS OF DAYTIME HEATING...ANY SHOWERS WILL QUICKLY
DIMINISH THIS EVENING AND CU FIELD OVER REMAINING TAF SITES WILL
ALSO DISSIPATE. WHILE THE AXIS OF THE UPPER LOW IS STILL ALONG AND
SSW OF THE REGION...THE ENERGY THAT IS SPARKING THE RAIN IN THE
SOUTHEAST WILL BE TRANSLATING EAST THROUGH PA TONIGHT.
IF THE CLEARING AND LIGHT WINDS ARE REALIZED...SOME DAYBREAK FOG
WITH GENERALLY MVFR VSBYS WILL OCCUR.
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...FRANKS
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1228 PM CDT SUN AUG 18 2013
.UPDATE...FOR 18Z AVIATION.
&&
.AVIATION...18Z TAF DISCUSSION.
VFR CONDITIONS AT ISSUANCE WILL BE SHORT LIVED THIS AFTERNOON AS
LIGHT RAINS AND LOWER CIGS MOVE INTO THE STATE FROM THE SOUTH.
THESE WILL LIKELY NOT BE CONSTANT...SO CIGS WILL BE UP AND DOWN
FROM HOUR TO HOUR...AND ANY HEAVIER RAINS WILL BRING REDUCED VIS.
WILL PREVAIL THE MOST LIKELY WORST-CASE SCENARIO THROUGH THE
AFTERNOON AND EVENING AT EACH TERMINAL. RAINS WILL TAPER OFF AFTER
00Z FOR KBNA AND KCKV...BUT MAY CONTINUE THROUGH THE NIGHT AT
KCSV.
ALSO LOOKING FOR LIFR TO IFR CONDITIONS FLIGHT CATEGORIES LATE
TONIGHT...AND IMPROVING TO MVFR BY 14-15Z ON MONDAY. WINDS WILL
BE LIGHT OUT OF THE SOUTHEAST.
UNGER
&&
.PREV DISCUSSION... /ISSUED 854 AM CDT SUN AUG 18 2013/
UPDATE...
RADAR CURRENTLY SHOWING LITTLE IF ANY SHOWER ACTIVITY THIS
MORNING. AS THE CLOSED UPPER LOW BEGINS TO OPEN UP AND WEAKEN
LATER TODAY...SOME ATMOSPHERIC DRYING CAN BE EXPECTED WITH TIME.
850 MB FLOW SHOWING SOME CYCLONIC CURVATURE BUT THE BETTER
CONVERGENCE IS WELL SOUTH. PLENTY OF CLOUDINESS AROUND AND THAT
WILL PREVENT MUCH IN THE WAY OF CAPE BUILDUP IN THE AFTERNOON.
HOWEVER...LATEST HRRR STILL SHOWING SOME DEVELOPMENT LATER THIS
MORNING WITH THE ACTIVITY EXPECTED TO LIFT NORTHWARD.
FOR THE UPDATE...WILL LOWER POPS TO A SMALL DEGREE ACROSS EASTERN
AND CENTRAL AREAS. OTW...REMAINDER OF FCST APPEARS TO BE ON TRACK.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
27
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
401 PM CDT SUN AUG 18 2013
.SHORT TERM...
Tonight and Tomorrow
Generally dry conditions with high temperatures near normal, with
low temperatures slightly below normal can be expected tonight and
tomorrow. Currently, showers and thunderstorms are developing across
much of the higher terrain of West Texas. The NAM and HRRR have a
pretty good handle on this convection, which is aided by a
disturbance rotating around the periphery of the upper level high
centered over New Mexico. At this time, I believe the majority of
the convection will remain west of our area late this
afternoon/evening, but an isolated shower or thunderstorm cannot be
ruled out across our extreme western counties. For now, I have kept
POPS below 15 percent and will continue to monitor.
Low temperatures overnight will once again fall into the 60s across
most of the area...as winds become light and dewpoint temperatures
remain in the 50s. Slightly above normal temperatures are forecast
on Monday, with highs generally in the mid to upper 90s. An isolated
shower is once again possible across mainly the northern Edwards
Plateau or Western Concho Valley on Monday, but coverage should
remain isolated enough to negate a mention in the grids at this
time.
Daniels
Monday night through Wednesday
Look for dry conditions and temperatures close to seasonal normals.
The good news is flow aloft remains from the east. So, afternoon
highs will not be as hot as they could be, because the 850 mb
thermal ridge remains mainly west of our area. Thus, I`m thinking
highs mainly in the mid 90s and lows around 70 look reasonable.
Huber
.LONG TERM...
Wednesday night through Sunday
An upper-level disturbance may bring showers and thunderstorms to
some of our central and southern counties Thursday and Friday.
Models this run continue to bring an inverted upper-level trough
into our area during the Thursday to Friday time frame. The GFS MOS
data still does not indicate anything other than around a 10 percent
chance for rain for this time frame. However, I decided to continue
the slight chance pops as we had in our previous forecast package,
especially given the potential for at least some rain with easterly
waves this time of year. Otherwise, cooler air at 850 mb continues
to move over West Central Texas for all periods of the long term.
Thus, I`m expecting afternoon highs at or possibly a degree or two
below seasonal normals, with overnight lows very close to
persistence.
Huber
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 68 97 68 94 70 / 5 5 5 5 5
San Angelo 67 99 68 95 70 / 5 5 5 5 5
Junction 65 97 68 95 68 / 5 0 5 10 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
Daniels/Huber
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
127 PM EDT SUN AUG 18 2013
.SYNOPSIS...
A COOL WEDGE OF HIGH PRESSURE WILL REMAIN SITUATED ALONG
THE LEE OF THE CENTRAL APPALACHIANS THIS MORNING BEFORE
SLOWLY WEAKENING FROM WEST TO EAST THIS AFTERNOON. LOW
PRESSURE TRACKING ALONG COASTAL NORTH CAROLINA WILL PASS
OFFSHORE LATER TODAY AHEAD OF ANOTHER UPPER LEVEL DISTURBANCE
THAT WILL AFFECT THE MOUNTAINS OVERNIGHT. THIS UPPER LEVEL
TROUGH OF LOW PRESSURE IS EXPECTED TO PASS ACROSS THE REGION
FROM THE WEST MONDAY KEEPING THE THREAT OF SHOWERS AROUND
INTO MONDAY EVENING.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM EDT SUNDAY...
12Z RNK SOUNDING SHOWS AN IMPRESSIVE WEDGE FOR LATE AUGUST WITH
EAST/NORTHEAST WINDS UP TO 750 MB. ABV THIS LAYER...WINDS HAVE
ALREADY VEERED TO THE SOUTHWEST AND THESE VEERING WINDS ABV THE
WEDGE WILL CONTINUE THROUGH THE DAY RESULTING IN A MORE SHALLOW
LAYER OF MOISTURE AND REDUCED PRECIP RATES.
CHANNELED VORTICITY MOVING THROUGH THE SOUTHWEST FLOW ALOFT WILL
CONTINUE TO GENERATE LIGHT PRECIP...ESPECIALLY ALONG THE THE BLUE
RIDGE AND THE EASTERN SLOPES WITH A LOW LEVEL EASTERLY COMPONENT
TO THE WIND. THEREFORE...CONTINUED LIKELY POPS FOR THIS AREA
THROUGH MUCH OF THE DAY.
VISIBLE SATELLITE IMAGERY IS SHOWING SOME BREAKS IN THE CLOUDS
ACROSS FAR SW VA AND NE TN. MESOSCALE MODELS INCLUDING THE LOCAL
WRF AND HRRR SUGGEST THESE BREAKS MAY EXPAND INTO THE FAR WESTERN
PORTION OF THE FORECAST AREA...INCLUDING NW NC...THE MOUNTAIN
EMPIRE...THE CLINCH VALLEY AND PERHAPS BLF. THIS WILL GENERATE
SOME INSTABILITY AND MAY IGNITE SCATTERED SHOWERS AND ISOLATED
STORMS LATE THIS AFTERNOON.
IN THE EAST...BROUGHT DOWN HIGH TEMPS A COUPLE OF DEGREES AS WE
EXPECT THE WEDGE TO HOLD IN THIS AREA THROUGH THE DAY.
UPPER LOW OPENS UP THIS EVENING WITH CHANNELED VORTICITY CLIPPING
ACROSS THE WEST OVERNIGHT. FORECAST PWATS SHOW SOME DECREASE PER
MORE OF A WEST/SW FLOW...WHILE DYNAMICS LOOK QUITE GOOD UNDER THE
RIGHT REAR OF A 3H JET MAX. PROGGED SWATH OF LOW LEVEL CONVERGENCE
ALSO INDICATED ESPCLY OVER THE SOUTHERN TIER THROUGH MUCH OF THE
NIGHT. MODELS IN TURN DEVELOP A BAND OF CONVECTION OVER THE WEST
EARLY TONIGHT...AND MOVE IT EAST ACROSS THE SOUTHERN TIER COUNTIES
WITH SOME DEGREE OF UNCERTAINTY IN HOW ORGANZIED COVERAGE MAY BE.
THINK ENOUGH CONFIDENCE TO INCLUDE ANOTHER ROUND OF LIKELY POPS
SOUTH TONIGHT WITH DECENT CHANCES ELSW EXCEPT PERHAPS THE FAR EAST
WHERE SOME OF THE WEDGE MAY STILL BE LINGERING. KEPT LOWS IN
BETWEEN THE COOLER MET AND WARMER MAV MOS GIVEN CLOUDS/SHRA AND
ONLY A SLIGHT DECREASE IN DEWPOINTS LATE.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
AS OF 256 AM EDT SUNDAY...
A CLOSED LOW TO THE WEST WILL OPEN INTO A TROUGH ON MONDAY
AS IT TRACKS OVER THE OHIO VALLEY. MODELS SHOWING ONE
SIGNIFICANT SHORT WAVE COMING ACROSS THE AREA MONDAY
MORNING...THEN ANY SHORT WAVES IN THE AFTERNOON STAY SOUTH.
WILL HAVE THE HIGHEST POPS FOR SHOWERS IN THE MORNING...TAPERING
TO SCATTERED CONVECTION IN THE AFTERNOON. FROM MONDAY
AFTERNOON INTO MID WEEK...THE WEATHER PATTERN SHIFTS BACK TO
MOSTLY DIURNAL CONVECTION...FIRING IN THE AFTERNOON...WANING
DURING THE EVENING. THE BEST AREAL COVERAGE OF CONVECTION WILL
BE TO THE SOUTH WHERE THE HIGHEST AMOUNT OF MOISTURE WILL RESIDE.
MORNING SHOWERS AND CLOUDS WILL KEEP MONDAY AFTERNOONS HIGH A
FEW DEGREES COOLER THAN NORMAL. HOWEVER...TEMPERATURES WILL BE
WARMER THAN THIS WEEKEND WITH 70S IN THE WEST TO LOWER 80S IN
THE EAST. TEMPERATURES ARE BACK TO NORMAL ON TUESDAY WITH NEAR
80F IN THE WEST TO MID TO UPPER 80S ACROSS THE EAST.
&&
.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 /18Z SUNDAY THROUGH FRIDAY/...
AS OF 120 PM EDT SUNDAY...
WITH WEDGE REMAINING ALONG THE EASTERN SEABOARD...DEEP MOISTURE PLUME...
AND A NEVER ENDING STREAM OF AMORPHOUS SHORT WAVE ENERGY WAFTING BY...
THERE DOES NOT APPEAR TO BE A VERY COMPELLING REASON TO BUY OFF ON THE
BIG IMPROVEMENT ADVERTISED BY MOS FOR CIGS...WITH THE POSSIBLE EXCEPTION
OF KBLF IN THE SHORT TERM. THUS...WILL TREND THINGS TOWARD A PERSISTANCE
FORECAST AND KEEP CIGS LOW. WITH NO CLEAR CUT DYNAMIC FEATURES TO LATCH
ON TO WILL USE SHRA AS PREVAILING WX OR IN VICINITY AT ALL SITES
THROUGH THE PERIOD...THOUGH EXPECT THE PCPN TO GENERALLY BE ON
THE LIGHT/SPOTTY SIDE.
AS SFC LOW ALONG THE COAST PULLS AWAY THE HIGH PRESSURE CENTER WILL BUILD
SOUTHWARD AND OUT OF THE DEATH WEDGE POSITION. THUS AFTER DAYBREAK TOMORROW...
THINGS SHOULD MIX OUT AND WINDS LOOK SHIFT TO A LIGHT SWLY DIRECTION. EXPECT
A BRIEF IMPROVEMENT EARLY TOMORROW...POSSIBLY TO VFR...BEFORE CONVECTIVE CLOUDS
REDEVELOP AND TURN INTO CONVECTIVE PCPN.
...AVIATION EXTENDED...
WILL TRANSITION TO A WEATHER PATTERN MORE TYPICAL OF MID AUGUST BY
TUESDAY...WITH SOUTHERLY FLOW BECOMING REESTABLISHED...AND
RAINFALL TAKING THE FORM OF DIURNALLY DRIVEN SHOWERS AND
THUNDERSTORMS. TOWARD THE END OF THE WEEK...LONG RANGE MODELS
BEGIN TO DISAGREE AS TO THE PLACEMENT OF AN UPPER RIDGE...WITH THE
GFS MODEL KEEPING THE RIDGE OVER THE PLAINS...WHILE THE ECMWF
CALLS FOR THE RIDGE TO BUILD EAST OF THE MISSISSIPPI RIVER.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...DS/JH
NEAR TERM...JH/PH
SHORT TERM...RCS
LONG TERM...DS
AVIATION...MBS
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST 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 18Z TAF ISSUANCE
ISSUED AT 1210 PM CDT SUN AUG 18 2013
VFR CONDITIONS WILL PROVIDE GOOD FLYING WEATHER OVER THE
TAF PERIOD. A TIGHTER PRESSURE GRADIENT WILL PREVENT FOG FROM
FORMING LATE TONIGHT. THEN A WEAK DISTURBANCE WILL APPROACH
NORTH-CENTRAL WISCONSIN MONDAY MORNING. CLOUDS WILL BE ON THE
INCREASE DURING THE MORNING HOURS WITH A LOW PROBABILITY OF SHOWERS
ARRIVING. CHANCES IMPROVE MARGINALLY DURING THE AFTERNOON.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1210 PM CDT SUN AUG 18 2013
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND MONDAY
ISSUED AT 350 AM CDT SUN AUG 18 2013
THE MAIN FCST CONCERNS ARE TEMPERATURES AND SMALL PCPN CHANCES.
WV IMAGERY AND RUC ANALYSIS INDICATED UPPER LEVEL RIDGING OVER THE
ROCKIES AND NORTHERN PLAINS...WITH STRONG ZONAL FLOW OVER THE
NORTHERN TIER OF THE U.S. AND CANADA. THE MAIN SHORT-WAVE ENERGY
WAS TRACKING THROUGH SOUTHERN SASK AND MANITOBA. THE WSTRN
PERIPHERY OF A LARGE SFC HIGH PRESSURE SYSTEM WAS STILL SITUATED
OVER WI...WITH STRONG RETURN FLOW SETTING UP IN ADVANCE OF A COLD
FRONT MOVG THROUGH THE DAKOTAS.
HIGH PRESSURE WILL ONCE AGAIN DOMINATE OUR WEATHER TODAY...WITH
UPPER LEVEL ENERGY REMAINING WELL TO OUR NORTH. EXPECT DIURNAL
CUMULUS CLOUDS TO DEVELOP AGAIN TODAY...ALONG WITH AN INCREASE IN
HIGH CLOUDS ACROSS N WI. MIXING THROUGH 825-800 MB SHOULD YIELD
MAX TEMPS IN THE LOWER TO MIDDLE 80S.
A S/W TROF IS EXPECTED TO MOVE INTO NW WI LATE TONIGHT. SOME WAA
WILL ALSO OCCUR OVER NW/NC WI...WITH SOME ELEVATED INSTABILITY
WORKING ITS WAY TOWARD OUR NW COUNTIES BY MORNING. GENERAL MODEL
CONCENSUS IS TO KEEP ANY PCPN JUST NW OF GRB CWA THROUGH 12Z...
SO WILL GO WITH A DRY FCST FOR NOW. THINK THAT FOG WILL LESS OF
THREAT THAN IT HAS BEEN FOR THE PAST SEVERAL NIGHTS...AS THE SFC
PRESSURE GRADIENT TIGHTENS UP AND BOUNDARY LAYER FLOW INCREASES TO
15-20 KTS. TEMPS SHOULD BE A FEW DEGREES WARMER...WITH LOWS IN THE
50S.
ON MONDAY...A S/W TROF WILL MOVE THROUGH NORTHERN WI...PERHAPS
TRIGGERING ISOLD TSTMS WITHIN A WEAK INSTABILITY AXIS OVER NC AND
FAR NE WI. INCREASING SW WINDS SHOULD PULL WARMER TEMPS INTO THE
REGION...BOOSTING HIGHS INTO THE MIDDLE TO UPPER 80S AT MOST
LOCATIONS.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
ISSUED AT 350 AM CDT SUN AUG 18 2013
SUMMER TIME PATTERN EXPECTED THROUGH MUCH OF THE WEEK. THE BIG
STORY WILL BE THE HEAT WITH HIGHS WELL INTO THE 80S AND SOME 90S
TUESDAY AND WEDNESDAY. COLD FRONT IS EXPECTED TO ENTER NORTHWEST
WISCONSIN WEDNESDAY AFTERNOON...PASS ACROSS THE AREA WEDNESDAY
NIGHT AND THEN PUSH SOUTH OF THE AREA ON THURSDAY. WITH THE HEAT
AND HUMIDITY IN PLACE ALONG WITH 0-6 KM SHEAR...THERE IS STILL
SOME POTENTIAL FOR STRONG OR SEVERE STORMS ACROSS THE AREA...WHICH
IS ALREADY IN THE HAZARDOUS WEATHER OUTLOOK.
BEYOND WEDNESDAY NIGHT...IT APPEARS THE GFS/CANADIAN ARE TAKING
THE LEAD IN MODEL TRENDS FOR THURSDAY/THURSDAY NIGHT. THIS IS UNUSUAL
SINCE THE ECMWF USUALLY PERFORMS BETTER IN THE OUTER PERIODS. ON THE
00Z RUN TONIGHT...THE GFS/CANADIAN PUSH THE FRONT FAR ENOUGH SOUTH
OF THE AREA TO ALLOW FOR DRY CONDITIONS LATER THURSDAY MORNING
INTO THURSDAY AFTERNOON. HAVE REMOVED POPS ACROSS THE NORTH ON
THURSDAY AND CONTINUED A SMALL CHANCE ACROSS THE SOUTH. FIGURING
THE SMALL CHANCE WOULD BE FOR ANY LINGERING MORNING CONVECTION.
STILL A LOT OF UNCERTAINTY WHEN CONVECTION WOULD RETURN THURSDAY
NIGHT/FRIDAY OR EVEN FRIDAY NIGHT AMONG THE MODELS. WILL LEAVE
FRIDAY/SATURDAY FORECAST ALONE DUE TO LARGE MODEL UNCERTAINTY.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1210 PM CDT SUN AUG 18 2013
VFR CONDITIONS WILL PROVIDE GOOD FLYING WEATHER OVER THE
TAF PERIOD. A TIGHTER PRESSURE GRADIENT WILL PREVENT FOG FROM
FORMING LATE TONIGHT. THEN A WEAK DISTURBANCE WILL APPROACH
NORTH-CENTRAL WISCONSIN MONDAY MORNING. CLOUDS WILL BE ON THE
INCREASE DURING THE MORNING HOURS WITH A LOW PROBABILITY OF SHOWERS
ARRIVING. CHANCES IMPROVE MARGINALLY DURING THE AFTERNOON.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....KIECKBUSCH
LONG TERM......ECKBERG
AVIATION.......MPC