Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/20/15
AREA FORECAST DISCUSSION
NWS NEW YORK NY
210 PM EDT TUE AUG 18 2015
.SYNOPSIS...
THE REGION REMAINS IN BETWEEN HIGH PRESSURE OVER THE CANADIAN
MARITIMES AND A COLD FRONT SLOWLY ADVANCING TO THE EAST FROM THE
MIDWEST THROUGH THURSDAY NIGHT. THIS FRONT THEN SLOWLY CROSSES
THE TRI- STATE FRIDAY AND FRIDAY NIGHT. THE FRONT STALLS OUT JUST
TO THE EAST AND SOUTH OF THE AREA...AND WEAKENS... AS HIGH
PRESSURE SLOWLY BUILDS IN FROM THE NORTHEAST THROUGH THE WEEKEND.
ANOTHER COLD FRONT APPROACHES FROM THE WEST ON MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
VERY WARM AND HUMID AIRMASS REMAINS OVER THE REGION WITH SFC TEMPS
IN THE UPPER 80S TO LOW 90S AND SFC DEWPOINTS GENERALLY IN THE 60S
TO NEAR 70. AS A RESULT...MU CAPE VALUES FROM 0-10 KM RANGE FROM
1500-2000 J/KG.
12Z NAM HAS BACKED OFF ON SHRA/TSRA OVER THE AREA THIS
AFTERNOON...BUT THE LATEST HRRR KEEPS SCT SHRA/TSRA ACROSS
INTERIOR PORTIONS OF SOUTHERN CT. WITH AFTERNOON SEA BREEZES
DEVELOPING AND POSSIBLE OUTFLOW BOUNDARIES FROM ANY DEVELOPING
STORMS UPSTREAM...WILL KEEP CHANCE POPS IN THOSE AREAS.
THE HEAT INDEX THIS AFTERNOON WILL TOP OFF IN THE LOW 90S ACROSS
MUCH OF THE CWA...AND INTO THE MID 90S FOR NE NJ AND POSSIBLY FOR
PARTS OF NYC.
THERE IS A MODERATE RISK OF RIP CURRENTS FORECAST FOR THE OCEAN
BEACHES TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
ANY LINGERING SHOWERS...MOST LIKELY CONFINED TO NORTH OF THE
CITY...SHOULD END BY MIDNIGHT AS THE ATMOSPHERE STABILIZES. WINDS
BACK A LITTLE MORE TOWARDS SSE...MAINTAINING PLENTY OF LOW LEVEL
MOISTURE. NOT SO SURE WE SEE STRATUS WITH WATER TEMPS SO
WARM...AND WOULD HAVE LIKE TO SEEN THE LOW LEVEL MOISTURE PROGGED
DEEPER TO PUT IT INTO THE GRIDS...BUT WILL AT LEAST KEEP IN PATCHY
FOG FOR THE SUBURBS LATE AT NIGHT. THAT SAID...SOME STRATUS IS NOT
OUT OF THE QUESTION.
WITH WINDS CONTINUING TO BACK A LITTLE MORE ACROSS THE CWA AND
MOISTURE WELL AHEAD OF A COLD FRONT OVER THE GREAT LAKES SHIFTING
CLOSER...THE BEST MOISTURE CONVERGENCE AND CHANCE OF SHOWERS/TSTMS
ENDS UP BEING MOSTLY WEST OF THE HUDSON DURING WEDNESDAY. STORM
MOTION WILL BE SLOW ONCE AGAIN...SO LOCALLY HEAVY DOWNPOURS WILL BE
POSSIBLE. HIGHS TEMP FORECAST IS SLIGHTLY WARMER THAN A MAV/NAM
MOS BLEND.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
NORTHERN STREAM RIDGING SLOWLY EXITS TO THE NORTHEAST WEDNESDAY
NIGHT AND THURSDAY. SUBSIDENCE FROM THE RIDGE WILL HELP TO LIMIT
POPS TO SLIGHT CHANCE WEDNESDAY NIGHT...AND AT MOST CHANCE ON
THURSDAY. INSTABILITY IN THE WEDNESDAY NIGHT-THURSDAY TIME FRAME IS
VERY WEAK...IF NOT NONE-EXISTENT BASED ON MODEL (AT MOST A FEW
HUNDRED J/KG OF CAPE AND SHOWALTERS GENERALLY ABOVE 3)...SO HAVE
LIMITED MENTION OF THUNDER TO ONLY THOSE AREAS WITH CHANCE POPS (FAR
NW ZONES THURSDAY)...AND THEN CAPPED THE PROBABILITY OF THUNDER TO
SLIGHT CHANCE. GENERALLY EXPECT ANY CONVECTION TO BE OF THE MORE
MISS THAN HIT VARIETY WEDNESDAY NIGHT AND THURSDAY...WITH MOST AREAS
TO THE EAST OF NYC SEEING LITTLE IF ANY PRECIPITATION DURING THIS
TIME FRAME.
FOR LOWS WEDNESDAY NIGHT A BLEND OF ECS/MET/MAV GUIDANCE AND NAM 2-
METER TEMPERATURES WAS USED...WITH VALUES FORECAST TO BE AROUND 5
DEGREES ABOVE NORMAL. A BLEND OF MAV/MET GUIDANCE...MIXING DOWN FROM
975-875 HPA PER BUFKIT SOUNDINGS...AND NAM 2-METER TEMPERATURES WAS
USED FOR HIGHS ON THURSDAY...WITH READINGS EXPECTED TO BE WITHIN A
FEW DEGREES OF EITHER SIDE OF NORMAL.
A NORTHERN STREAM TROUGH LIFTS TO THE N THEN NE THURSDAY NIGHT INTO
FRIDAY EVENING...WITH ITS ASSOCIATED SURFACE COLD FRONT PASSING
THROUGH JUST AHEAD OF IT. SHOULD HAVE SUFFICIENT FORCING MAINLY OVER
WESTERN ZONES TO WARRANT LIKELY POPS THURSDAY NIGHT THERE...WITH
CHANCE POPS OR LESS FARTHER EAST...THEN LIKELY POPS THROUGHOUT ON
FRIDAY...EXCEPT OVER FAR SE ZONES WHERE LIMITED TO CHANCE DUE TO THE
SLOW EASTWARD PROGRESSION OF THE SYSTEM AND THAT THE BEST FORCING IS
LIFTING AWAY FROM THIS AREA.
THE FACT THAT THE BEST FORCING IS LIFTING AWAY FROM THE AREA THE
ENTIRE TIME IS OF SOME CONCERN...AND IS THE REASON WHY POPS WERE NOT
RAISED TO CATEGORICAL. DEPENDING ON EXACTLY HOW THINGS PLAY
OUT...THERE IS SOME POTENTIAL THAT EVEN LIKELY POPS COULD BE
OVERDONE. PROBABILITY OF THUNDER WAS CAPPED AGAIN AT CHANCE DUE TO
CONTINUED LIMITED INSTABILITY IN THE LOW LEVELS. GIVEN THE
OVERALL TREND...HAVE CONTINUED TO MENTION LOCALLY HEAVY RAIN
THURSDAY NIGHT/FRIDAY IN AREAS WITH LIKELY POPS. REFER TO THE
HYDROLOGY SECTION OF THE AFD FOR POTENTIAL QPF AND ANY IMPACTS.
THE WEATHER COULD THEN REMAIN UNSETTLED FROM FRIDAY NIGHT-MONDAY
WITH THE FRONT STALLING OUT NEARBY AND MULTIPLE SHORTWAVES PASSING
OVER THE AREA IN SW FLOW ALOFT. FOR NOW HAVE CHANCE POPS FRIDAY
NIGHT AND SATURDAY WHEN THE COLD FRONT IS AT ITS CLOSEST...THEN
SLIGHT CHANCE POPS SATURDAY NIGHT-MONDAY WITH TWO EXCEPTIONS. THE
FIRST IS SUNDAY WHERE THERE ARE CHANCE POPS OVER THE NW 1/2 OF THE
CWA AS CONVECTION COULD BE DIURNALLY ENHANCED...THEN OVER THE NW 1/3
OF THE AREA ON MONDAY AHEAD OF AN ADVANCING CUTOFF LOW AND
ASSOCIATED TROUGH FORECAST TO MOVE INTO THE GREAT LAKES ON MONDAY.
FOR TEMPERATURES THURSDAY NIGHT-MONDAY A BLEND OF
MEX/MEN/EKD/ECE/ECM/WPC GUIDANCE WAS USED...WITH NAM 2-METER
TEMPERATURES MIXED IN AS WELL FOR THURSDAY NIGHT. LOWS ARE FORECAST
TO REMAIN ABOVE NORMAL IN THIS TIME FRAME WITH HIGHS NEAR TO
SLIGHTLY ABOVE NORMAL.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
ISOLATED SHOWERS AND A POSSIBLE THUNDERSTORM WELL NORTH AND WEST
OF NYC TERMINALS THIS AFTERNOON...PARTICULARLY NEAR KSWF.
OTHERWISE MAINLY VFR IS POSSIBLE WITH ANY LOWER CATEGORIES
RESULTING FROM NIGHTTIME COASTAL PATCHY FOG/LOW STRATUS TONIGHT.
BOTH NAM/GFS GUIDANCE SUGGEST IFR POSSIBLE IN CIGS AND VSBY FOR 6
HOUR PERIOD AFTER 07Z. WILL TREND FORECAST DOWNWARD AS A RESULT. S
FLOW 10-15KT THIS AFTERNOON. G20KT POSSIBLE KLGA. WINDS
DIMINISHING TONIGHT.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT:
HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. TIMING
AMENDMENTS POSSIBLE OVERNIGHT IN CIGS/VSBY.
KLGA FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. TIMING
AMENDMENTS POSSIBLE OVERNIGHT IN CIGS/VSBY.
KEWR FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. TIMING
AMENDMENTS POSSIBLE OVERNIGHT IN CIGS/VSBY.
KTEB FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. TIMING
AMENDMENTS POSSIBLE OVERNIGHT IN CIGS/VSBY.
KHPN FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. TIMING
AMENDMENTS POSSIBLE OVERNIGHT IN CIGS/VSBY.
KISP FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. TIMING
AMENDMENTS POSSIBLE OVERNIGHT IN CIGS/VSBY.
.OUTLOOK FOR 18Z WEDNESDAY THROUGH SATURDAY...
.18Z WED...ISOLD-SCT AFTN SHRA/TSTM POSSIBLE MAINLY FROM CITY
TERMINALS ON N/W. S-SW WINDS G15-20KT. MVFR OR LOWER POSSIBLE.
.WED NIGHT-THU...MVFR OR LOWER POSSIBLE WITH A LOW CHC OF SHRA.
RELATIVELY HIGHER CHC THU NEAR CITY TERMINALS AND N/W.
.THU NIGHT-FRI NIGHT...MVFR OR LOWER POSSIBLE IN SHRA/TSTMS.
.SAT AND SUN...MVFR POSSIBLE WITH A CHANCE OF SHRA/TSTMS.
&&
.MARINE...
PREVAILING WINDS AND SEAS SHOULD REMAIN BELOW SCA CRITERIA
THROUGH WEDNESDAY...BUT A FEW GUSTS TO 25 KT WILL BE POSSIBLE NEAR
THE NY HARBOR ENTRANCE LATE THIS AFTERNOON/EARLY EVENING.
A RELAXED PRESSURE GRADIENT OVER THE REGION WILL KEEP WINDS AT 10 KT
OR LESS WEDNESDAY NIGHT THROUGH SATURDAY. SEAS ON THE COASTAL OCEAN
WATERS SHOULD BE 3 FT OR LESS AND ON THE NON-OCEAN WATERS 1 FT OR
LESS IN THIS TIME FRAME AS A RESULT.
&&
.HYDROLOGY...
ALTHOUGH SHOWER/THUNDERSTORM COVERAGE IS EXPECTED TO BE
RELATIVELY SPARSE TODAY...ANYTHING THAT FORMS WILL LIKELY REMAIN
NEARLY STATIONARY OR MOVE VERY SLOWLY...WITH POTENTIAL TO DUMP A
QUICK ISOLATED 1-2 INCHES OF RAIN. LOCALIZED FLASH FLOODING MAINLY
FOR URBAN AREAS IS POSSIBLE...BUT AGAIN...COVERAGE AND OVERALL
CHANCES OF RAINFALL ARE TOO LOW FOR CONSIDERATION OF A WATCH.
FOR WEDNESDAY...SCATTERED HEAVY SHOWERS AND THUNDERSTORMS MAY
CAUSE MAINLY MINOR URBAN FLOODING.
NO SIGNIFICANT WIDESPREAD PRECIPITATION IS EXPECTED
WEDNESDAY NIGHT AND THURSDAY.
FOR NOW FORECASTING 2/10 TO AROUND 1 INCH OF RAIN THURSDAY NIGHT
AND FRIDAY...WITH HIGHEST AMOUNTS OVER NW ZONES AND LOWEST AMOUNTS
OVER FAR E ZONES. WITH STORM MOTION FORECAST TO BE 5 KT OR
LESS...AND PRECIPITABLE WATERS FORECAST ON AVERAGE TO BE BETWEEN
1.5-2 INCHES THURSDAY NIGHT AND FRIDAY (WITH QUITE A BIT OF
DISCREPANCY BETWEEN INDIVIDUAL MODELS WITH THE NAM GOING BELOW 1.5
INCHES AND THE GFS ABOVE 2 INCHES)...THERE IS THE POTENTIAL FOR
ANY STRONGER STORM TO PRODUCE LOCALLY HEAVY RAINFALL. SINCE STORMS
ARE FORECAST TO BE SLOW MOVING...THERE IS THE POTENTIAL FOR
LOCALIZED MINOR URBAN/POOR DRAINAGE FLOODING.
IF PRECIPITABLE WATERS END UP BEING TOWARDS THE HIGHER END OF THE
RANGE...ESPECIALLY IF THE GFS ENDS UP BEING CORRECT...THEN THERE
WOULD BE THE POTENTIAL FOR LOCALIZED FLASH FLOODING AS
WELL...ESPECIALLY IN URBAN AREAS. CONFIDENCE IN WIDESPREAD FLASH
FLOODING CURRENTLY NOT HIGH ENOUGH TO MENTION IN THE HWO...WITH
LARGE DIFFERENCES IN FORECAST PRECIPITABLE WATERS BEING THE
LIMITING FACTOR.
WHILE THE MAIN THREAT FOR LOCALLY HEAVY RAINFALL IS THURSDAY NIGHT
AND FRIDAY...IT IS POSSIBLE THE THREAT COULD LINGER INTO FRIDAY
NIGHT DEPENDING ON EXACTLY HOW FAST THE COLD FRONT SLIDES TO THE
EAST.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JC/MALOIT
NEAR TERM...MPS
SHORT TERM...JC
LONG TERM...MALOIT
AVIATION...IRD
MARINE...JC/MALOIT
HYDROLOGY...JC/MALOIT
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1157 AM EDT TUE AUG 18 2015
.SYNOPSIS...
THE REGION REMAINS IN BETWEEN HIGH PRESSURE OVER THE CANADIAN
MARITIMES AND A COLD FRONT SLOWLY ADVANCING TO THE EAST FROM THE
MIDWEST THROUGH THURSDAY NIGHT. THIS FRONT THEN SLOWLY CROSSES
THE TRI- STATE FRIDAY AND FRIDAY NIGHT. THE FRONT STALLS OUT JUST
TO THE EAST AND SOUTH OF THE AREA...AND WEAKENS... AS HIGH
PRESSURE SLOWLY BUILDS IN FROM THE NORTHEAST THROUGH THE WEEKEND.
ANOTHER COLD FRONT APPROACHES FROM THE WEST ON MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
VERY WARM AND HUMID AIRMASS REMAINS OVER THE REGION WITH SFC TEMPS
IN THE UPPER 80S TO LOW 90S AND SFC DEWPOINTS GENERALLY IN THE 60S
TO NEAR 70. AS A RESULT...MU CAPE VALUES FROM 0-10 KM RANGE FROM
1500-2000 J/KG.
12Z NAM HAS BACKED OFF ON SHRA/TSRA OVER THE AREA THIS
AFTERNOON...BUT THE LATEST HRRR KEEPS SCT SHRA/TSRA ACROSS
INTERIOR PORTIONS OF SOUTHERN CT. WITH AFTERNOON SEA BREEZES
DEVELOPING AND POSSIBLE OUTFLOW BOUNDARIES FROM ANY DEVELOPING
STORMS UPSTREAM...WILL KEEP CHANCE POPS IN THOSE AREAS.
THE HEAT INDEX THIS AFTERNOON WILL TOP OFF IN THE LOW 90S ACROSS
MUCH OF THE CWA...AND INTO THE MID 90S FOR NE NJ AND POSSIBLY FOR
PARTS OF NYC.
THERE IS A MODERATE RISK OF RIP CURRENTS FORECAST FOR THE OCEAN
BEACHES TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
ANY LINGERING SHOWERS...MOST LIKELY CONFINED TO NORTH OF THE
CITY...SHOULD END BY MIDNIGHT AS THE ATMOSPHERE STABILIZES. WINDS
BACK A LITTLE MORE TOWARDS SSE...MAINTAINING PLENTY OF LOW LEVEL
MOISTURE. NOT SO SURE WE SEE STRATUS WITH WATER TEMPS SO
WARM...AND WOULD HAVE LIKE TO SEEN THE LOW LEVEL MOISTURE PROGGED
DEEPER TO PUT IT INTO THE GRIDS...BUT WILL AT LEAST KEEP IN PATCHY
FOG FOR THE SUBURBS LATE AT NIGHT. THAT SAID...SOME STRATUS IS NOT
OUT OF THE QUESTION.
WITH WINDS CONTINUING TO BACK A LITTLE MORE ACROSS THE CWA AND
MOISTURE WELL AHEAD OF A COLD FRONT OVER THE GREAT LAKES SHIFTING
CLOSER...THE BEST MOISTURE CONVERGENCE AND CHANCE OF SHOWERS/TSTMS
ENDS UP BEING MOSTLY WEST OF THE HUDSON DURING WEDNESDAY. STORM
MOTION WILL BE SLOW ONCE AGAIN...SO LOCALLY HEAVY DOWNPOURS WILL BE
POSSIBLE. HIGHS TEMP FORECAST IS SLIGHTLY WARMER THAN A MAV/NAM
MOS BLEND.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
NORTHERN STREAM RIDGING SLOWLY EXITS TO THE NORTHEAST WEDNESDAY
NIGHT AND THURSDAY. SUBSIDENCE FROM THE RIDGE WILL HELP TO LIMIT
POPS TO SLIGHT CHANCE WEDNESDAY NIGHT...AND AT MOST CHANCE ON
THURSDAY. INSTABILITY IN THE WEDNESDAY NIGHT-THURSDAY TIME FRAME IS
VERY WEAK...IF NOT NONE-EXISTENT BASED ON MODEL (AT MOST A FEW
HUNDRED J/KG OF CAPE AND SHOWALTERS GENERALLY ABOVE 3)...SO HAVE
LIMITED MENTION OF THUNDER TO ONLY THOSE AREAS WITH CHANCE POPS (FAR
NW ZONES THURSDAY)...AND THEN CAPPED THE PROBABILITY OF THUNDER TO
SLIGHT CHANCE. GENERALLY EXPECT ANY CONVECTION TO BE OF THE MORE
MISS THAN HIT VARIETY WEDNESDAY NIGHT AND THURSDAY...WITH MOST AREAS
TO THE EAST OF NYC SEEING LITTLE IF ANY PRECIPITATION DURING THIS
TIME FRAME.
FOR LOWS WEDNESDAY NIGHT A BLEND OF ECS/MET/MAV GUIDANCE AND NAM 2-
METER TEMPERATURES WAS USED...WITH VALUES FORECAST TO BE AROUND 5
DEGREES ABOVE NORMAL. A BLEND OF MAV/MET GUIDANCE...MIXING DOWN FROM
975-875 HPA PER BUFKIT SOUNDINGS...AND NAM 2-METER TEMPERATURES WAS
USED FOR HIGHS ON THURSDAY...WITH READINGS EXPECTED TO BE WITHIN A
FEW DEGREES OF EITHER SIDE OF NORMAL.
A NORTHERN STREAM TROUGH LIFTS TO THE N THEN NE THURSDAY NIGHT INTO
FRIDAY EVENING...WITH ITS ASSOCIATED SURFACE COLD FRONT PASSING
THROUGH JUST AHEAD OF IT. SHOULD HAVE SUFFICIENT FORCING MAINLY OVER
WESTERN ZONES TO WARRANT LIKELY POPS THURSDAY NIGHT THERE...WITH
CHANCE POPS OR LESS FARTHER EAST...THEN LIKELY POPS THROUGHOUT ON
FRIDAY...EXCEPT OVER FAR SE ZONES WHERE LIMITED TO CHANCE DUE TO THE
SLOW EASTWARD PROGRESSION OF THE SYSTEM AND THAT THE BEST FORCING IS
LIFTING AWAY FROM THIS AREA.
THE FACT THAT THE BEST FORCING IS LIFTING AWAY FROM THE AREA THE
ENTIRE TIME IS OF SOME CONCERN...AND IS THE REASON WHY POPS WERE NOT
RAISED TO CATEGORICAL. DEPENDING ON EXACTLY HOW THINGS PLAY
OUT...THERE IS SOME POTENTIAL THAT EVEN LIKELY POPS COULD BE
OVERDONE. PROBABILITY OF THUNDER WAS CAPPED AGAIN AT CHANCE DUE TO
CONTINUED LIMITED INSTABILITY IN THE LOW LEVELS. GIVEN THE
OVERALL TREND...HAVE CONTINUED TO MENTION LOCALLY HEAVY RAIN
THURSDAY NIGHT/FRIDAY IN AREAS WITH LIKELY POPS. REFER TO THE
HYDROLOGY SECTION OF THE AFD FOR POTENTIAL QPF AND ANY IMPACTS.
THE WEATHER COULD THEN REMAIN UNSETTLED FROM FRIDAY NIGHT-MONDAY
WITH THE FRONT STALLING OUT NEARBY AND MULTIPLE SHORTWAVES PASSING
OVER THE AREA IN SW FLOW ALOFT. FOR NOW HAVE CHANCE POPS FRIDAY
NIGHT AND SATURDAY WHEN THE COLD FRONT IS AT ITS CLOSEST...THEN
SLIGHT CHANCE POPS SATURDAY NIGHT-MONDAY WITH TWO EXCEPTIONS. THE
FIRST IS SUNDAY WHERE THERE ARE CHANCE POPS OVER THE NW 1/2 OF THE
CWA AS CONVECTION COULD BE DIURNALLY ENHANCED...THEN OVER THE NW 1/3
OF THE AREA ON MONDAY AHEAD OF AN ADVANCING CUTOFF LOW AND
ASSOCIATED TROUGH FORECAST TO MOVE INTO THE GREAT LAKES ON MONDAY.
FOR TEMPERATURES THURSDAY NIGHT-MONDAY A BLEND OF
MEX/MEN/EKD/ECE/ECM/WPC GUIDANCE WAS USED...WITH NAM 2-METER
TEMPERATURES MIXED IN AS WELL FOR THURSDAY NIGHT. LOWS ARE FORECAST
TO REMAIN ABOVE NORMAL IN THIS TIME FRAME WITH HIGHS NEAR TO
SLIGHTLY ABOVE NORMAL.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
OFFSHORE HIGH PRESSURE THROUGH THE TAF PERIOD. MAINLY VFR WITH
ANY LOWER CATEGORIES RESULTING FROM NIGHTTIME COASTAL PATCHY
FOG/LOW STRATUS OR ISOLATED SHOWER/THUNDERSTORM ACTIVITY. S FLOW
UNDER 10 KT INCREASES TO 10-15 KT THIS AFTERNOON BEFORE
DIMINISHING AGAIN TONIGHT.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT:
HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. WINDS
COULD GUST OCCASIONALLY UP TO 20 KT LATE THIS AFTERNOON AND EARLY
THIS EVENING.
KLGA FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. WINDS
COULD GUST OCCASIONALLY UP TO 20 KT THIS AFTERNOON.
KEWR FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. WINDS
COULD GUST OCCASIONALLY UP TO 20 KT THIS AFTERNOON.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH
IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. WINDS
COULD GUST OCCASIONALLY UP TO 15 KT THIS AFTERNOON.
KHPN FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. WINDS
COULD GUST OCCASIONALLY UP TO 15 KT THIS AFTERNOON.
KISP FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. WINDS
COULD GUST OCCASIONALLY UP TO 20 KT THIS AFTERNOON.
.OUTLOOK FOR 12Z WEDNESDAY THROUGH SATURDAY...
.WED...ISOLD-SCT AFTN SHRA/TSTM POSSIBLE MAINLY FROM CITY
TERMINALS ON N/W. S-SW WINDS G15-20KT. MVFR OR LOWER POSSIBLE.
.WED NIGHT-THU...MVFR OR LOWER POSSIBLE WITH A LOW CHC OF SHRA.
RELATIVELY HIGHER CHC THU NEAR CITY TERMINALS AND N/W.
.THU NIGHT-FRI NIGHT...MVFR OR LOWER POSSIBLE IN SHRA/TSTMS.
.SATURDAY...MVFR POSSIBLE WITH A CHANCE OF SHRA/TSTMS.
&&
.MARINE...
PREVAILING WINDS AND SEAS SHOULD REMAIN BELOW SCA CRITERIA
THROUGH WEDNESDAY...BUT A FEW GUSTS TO 25 KT WILL BE POSSIBLE NEAR
THE NY HARBOR ENTRANCE LATE THIS AFTERNOON/EARLY EVENING.
A RELAXED PRESSURE GRADIENT OVER THE REGION WILL KEEP WINDS AT 10 KT
OR LESS WEDNESDAY NIGHT THROUGH SATURDAY. SEAS ON THE COASTAL OCEAN
WATERS SHOULD BE 3 FT OR LESS AND ON THE NON-OCEAN WATERS 1 FT OR
LESS IN THIS TIME FRAME AS A RESULT.
&&
.HYDROLOGY...
ALTHOUGH SHOWER/THUNDERSTORM COVERAGE IS EXPECTED TO BE
RELATIVELY SPARSE TODAY...ANYTHING THAT FORMS WILL LIKELY REMAIN
NEARLY STATIONARY OR MOVE VERY SLOWLY...WITH POTENTIAL TO DUMP A
QUICK ISOLATED 1-2 INCHES OF RAIN. LOCALIZED FLASH FLOODING MAINLY
FOR URBAN AREAS IS POSSIBLE...BUT AGAIN...COVERAGE AND OVERALL
CHANCES OF RAINFALL ARE TOO LOW FOR CONSIDERATION OF A WATCH.
FOR WEDNESDAY...SCATTERED HEAVY SHOWERS AND THUNDERSTORMS MAY
CAUSE MAINLY MINOR URBAN FLOODING.
NO SIGNIFICANT WIDESPREAD PRECIPITATION IS EXPECTED
WEDNESDAY NIGHT AND THURSDAY.
FOR NOW FORECASTING 2/10 TO AROUND 1 INCH OF RAIN THURSDAY NIGHT
AND FRIDAY...WITH HIGHEST AMOUNTS OVER NW ZONES AND LOWEST AMOUNTS
OVER FAR E ZONES. WITH STORM MOTION FORECAST TO BE 5 KT OR
LESS...AND PRECIPITABLE WATERS FORECAST ON AVERAGE TO BE BETWEEN
1.5-2 INCHES THURSDAY NIGHT AND FRIDAY (WITH QUITE A BIT OF
DISCREPANCY BETWEEN INDIVIDUAL MODELS WITH THE NAM GOING BELOW 1.5
INCHES AND THE GFS ABOVE 2 INCHES)...THERE IS THE POTENTIAL FOR
ANY STRONGER STORM TO PRODUCE LOCALLY HEAVY RAINFALL. SINCE STORMS
ARE FORECAST TO BE SLOW MOVING...THERE IS THE POTENTIAL FOR
LOCALIZED MINOR URBAN/POOR DRAINAGE FLOODING.
IF PRECIPITABLE WATERS END UP BEING TOWARDS THE HIGHER END OF THE
RANGE...ESPECIALLY IF THE GFS ENDS UP BEING CORRECT...THEN THERE
WOULD BE THE POTENTIAL FOR LOCALIZED FLASH FLOODING AS
WELL...ESPECIALLY IN URBAN AREAS. CONFIDENCE IN WIDESPREAD FLASH
FLOODING CURRENTLY NOT HIGH ENOUGH TO MENTION IN THE HWO...WITH
LARGE DIFFERENCES IN FORECAST PRECIPITABLE WATERS BEING THE
LIMITING FACTOR.
WHILE THE MAIN THREAT FOR LOCALLY HEAVY RAINFALL IS THURSDAY NIGHT
AND FRIDAY...IT IS POSSIBLE THE THREAT COULD LINGER INTO FRIDAY
NIGHT DEPENDING ON EXACTLY HOW FAST THE COLD FRONT SLIDES TO THE
EAST.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JC/MALOIT
NEAR TERM...MPS
SHORT TERM...JC
LONG TERM...MALOIT
AVIATION...IRD
MARINE...JC/MALOIT
HYDROLOGY...JC/MALOIT
AREA FORECAST DISCUSSION
NWS NEW YORK NY
742 AM EDT TUE AUG 18 2015
.SYNOPSIS...
THE REGION REMAINS IN BETWEEN HIGH PRESSURE OVER THE CANADIAN
MARITIMES AND A COLD FRONT SLOWLY ADVANCING TO THE EAST FROM THE
MIDWEST THROUGH THURSDAY NIGHT. THIS FRONT THEN SLOWLY CROSSES
THE TRI- STATE FRIDAY AND FRIDAY NIGHT. THE FRONT STALLS OUT JUST
TO THE EAST AND SOUTH OF THE AREA...AND WEAKENS... AS HIGH
PRESSURE SLOWLY BUILDS IN FROM THE NORTHEAST THROUGH THE WEEKEND.
ANOTHER COLD FRONT APPROACHES FROM THE WEST ON MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MADE MINOR CHANGES THIS UPDATE TO REFLECT THE LATEST TRENDS IN
OBSERVATIONS AND GUIDANCE. THE FORECAST APPEARS ON TRACK FOR NOW.
DO NOTE THAT LATEST HRRR NOW FAVORS PRECIPITATION FOR THE
REMAINDER OF THE DAY OVER NW ZONES. ALL GUIDANCE AND CURRENT RADAR
TRENDS SUGGEST CURRENT SHRA OVER NE NJ/LOWER HUDSON VALLEY WILL
DISSIPATE WITHIN THE NEXT HOUR OR SO.
UPPER RIDGE AXIS WILL BE TO OUR EAST TODAY. SURFACE BASED CAPES
WILL ONCE AGAIN INCREASE WITH ENOUGH MOISTURE FOR ISO/SCT
SHOWERS/THUNDERSTORMS ALONG SEA BREEZE AND OUTFLOW BOUNDARIES AS
WELL AS DIFFERENTIAL HEATING OVER THE FAR NW ZONES. STEERING FLOW
IS VERY WEAK...SO CELL MOVEMENT WILL BE SLOW WITH THE POTENTIAL OF
LOCALIZED FLOODING. COVERAGE AND PROBABILITY TOO LOW FOR ANY WATCH
CONSIDERATION.
AS FOR HIGH TEMPS...THE AFTERNOON 850MB TEMP IS PROGGED TO BE NEARLY
THE SAME OR ONLY UP TO A DEGREE COOLER THAN IT WAS YESTERDAY
AFTERNOON. EVEN SO...MAV/MET GUIDANCE WOULD SEEM TO BE TOO COOL WITH
HIGH TEMPS AT A FIRST GLANCE. BEST GUESS FOR THIS IS THAT AN
EARLIER/MORE WIDESPREAD FLOW OFF THE WATERS VERSUS YESTERDAY
CONTRIBUTES TO A SHALLOWER MIXING DEPTH AND LOWER 1000-850MB
THICKNESSES THIS AFTERNOON. WENT WITH MAV MOS GUIDANCE FOR MOST
SPOTS...WHICH WAS WARMER THAN NAM MOS IN MOST CASES AND BETTER
REFLECTS CURRENT THINKING.
SURFACE DEWPOINTS AND RESULTANT HEAT INDEX VALUES WILL BE TRICKY. S
TO LOCALLY SE WINDS WOULD HELP KEEP DEWPOINTS UP...BUT ODDLY ENOUGH
MODELS SHOW DRY AIR ADVECTING IN FROM THE SOUTH IN THE UPPER
PORTIONS OF THE BOUNDARY LAYER. THIS COULD HELP DROP THE DEWPOINTS A
COUPLE OF DEGREES IN THE MID TO LATE AFTERNOON HOURS. HAVE LOWERED
DEWPOINT FORECAST BY A DEGREE OR TWO FROM A GUIDANCE BLEND DURING
THESE HOURS. NO CONCERNS THEREFORE FOR ANY HEAT
ADVISORIES...ESPECIALLY WITH HIGH TEMPS AROUND 90 FOR THE WARMEST
SPOTS.
THERE IS A MODERATE RISK OF RIP CURRENTS FORECAST FOR THE OCEAN
BEACHES TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
ANY LINGERING SHOWERS...MOST LIKELY CONFINED TO NORTH OF THE CITY...
SHOULD END BY MIDNIGHT AS THE ATMOSPHERE STABILIZES. WINDS BACK A
LITTLE MORE TOWARDS SSE...MAINTAINING PLENTY OF LOW LEVEL MOISTURE.
NOT SO SURE WE SEE STRATUS WITH WATER TEMPS SO WARM...AND WOULD HAVE
LIKE TO SEEN THE LOW LEVEL MOISTURE PROGGED DEEPER TO PUT IT INTO
THE GRIDS...BUT WILL AT LEAST KEEP IN PATCHY FOG FOR THE SUBURBS
LATE AT NIGHT. THAT SAID...SOME STRATUS IS NOT OUT OF THE QUESTION.
WITH WINDS CONTINUING TO BACK A LITTLE MORE ACROSS THE CWA AND
MOISTURE WELL AHEAD OF A COLD FRONT OVER THE GREAT LAKES SHIFTING
CLOSER...THE BEST MOISTURE CONVERGENCE AND CHANCE OF SHOWERS/TSTMS
ENDS UP BEING MOSTLY WEST OF THE HUDSON DURING WEDNESDAY. STORM
MOTION WILL BE SLOW ONCE AGAIN...SO LOCALLY HEAVY DOWNPOURS WILL BE
POSSIBLE. HIGHS TEMP FORECAST IS SLIGHTLY WARMER THAN A MAV/NAM
MOS BLEND.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
NORTHERN STREAM RIDGING SLOWLY EXITS TO THE NORTHEAST WEDNESDAY
NIGHT AND THURSDAY. SUBSIDENCE FROM THE RIDGE WILL HELP TO LIMIT
POPS TO SLIGHT CHANCE WEDNESDAY NIGHT...AND AT MOST CHANCE ON
THURSDAY. INSTABILITY IN THE WEDNESDAY NIGHT-THURSDAY TIME FRAME IS
VERY WEAK...IF NOT NONE-EXISTENT BASED ON MODEL (AT MOST A FEW
HUNDRED J/KG OF CAPE AND SHOWALTERS GENERALLY ABOVE 3)...SO HAVE
LIMITED MENTION OF THUNDER TO ONLY THOSE AREAS WITH CHANCE POPS (FAR
NW ZONES THURSDAY)...AND THEN CAPPED THE PROBABILITY OF THUNDER TO
SLIGHT CHANCE. GENERALLY EXPECT ANY CONVECTION TO BE OF THE MORE
MISS THAN HIT VARIETY WEDNESDAY NIGHT AND THURSDAY...WITH MOST AREAS
TO THE EAST OF NYC SEEING LITTLE IF ANY PRECIPITATION DURING THIS
TIME FRAME.
FOR LOWS WEDNESDAY NIGHT A BLEND OF ECS/MET/MAV GUIDANCE AND NAM 2-
METER TEMPERATURES WAS USED...WITH VALUES FORECAST TO BE AROUND 5
DEGREES ABOVE NORMAL. A BLEND OF MAV/MET GUIDANCE...MIXING DOWN FROM
975-875 HPA PER BUFKIT SOUNDINGS...AND NAM 2-METER TEMPERATURES WAS
USED FOR HIGHS ON THURSDAY...WITH READINGS EXPECTED TO BE WITHIN A
FEW DEGREES OF EITHER SIDE OF NORMAL.
A NORTHERN STREAM TROUGH LIFTS TO THE N THEN NE THURSDAY NIGHT INTO
FRIDAY EVENING...WITH ITS ASSOCIATED SURFACE COLD FRONT PASSING
THROUGH JUST AHEAD OF IT. SHOULD HAVE SUFFICIENT FORCING MAINLY OVER
WESTERN ZONES TO WARRANT LIKELY POPS THURSDAY NIGHT THERE...WITH
CHANCE POPS OR LESS FARTHER EAST...THEN LIKELY POPS THROUGHOUT ON
FRIDAY...EXCEPT OVER FAR SE ZONES WHERE LIMITED TO CHANCE DUE TO THE
SLOW EASTWARD PROGRESSION OF THE SYSTEM AND THAT THE BEST FORCING IS
LIFTING AWAY FROM THIS AREA.
THE FACT THAT THE BEST FORCING IS LIFTING AWAY FROM THE AREA THE
ENTIRE TIME IS OF SOME CONCERN...AND IS THE REASON WHY POPS WERE NOT
RAISED TO CATEGORICAL. DEPENDING ON EXACTLY HOW THINGS PLAY
OUT...THERE IS SOME POTENTIAL THAT EVEN LIKELY POPS COULD BE
OVERDONE. PROBABILITY OF THUNDER WAS CAPPED AGAIN AT CHANCE DUE TO
CONTINUED LIMITED INSTABILITY IN THE LOW LEVELS. GIVEN THE
OVERALL TREND...HAVE CONTINUED TO MENTION LOCALLY HEAVY RAIN
THURSDAY NIGHT/FRIDAY IN AREAS WITH LIKELY POPS. REFER TO THE
HYDROLOGY SECTION OF THE AFD FOR POTENTIAL QPF AND ANY IMPACTS.
THE WEATHER COULD THEN REMAIN UNSETTLED FROM FRIDAY NIGHT-MONDAY
WITH THE FRONT STALLING OUT NEARBY AND MULTIPLE SHORTWAVES PASSING
OVER THE AREA IN SW FLOW ALOFT. FOR NOW HAVE CHANCE POPS FRIDAY
NIGHT AND SATURDAY WHEN THE COLD FRONT IS AT ITS CLOSEST...THEN
SLIGHT CHANCE POPS SATURDAY NIGHT-MONDAY WITH TWO EXCEPTIONS. THE
FIRST IS SUNDAY WHERE THERE ARE CHANCE POPS OVER THE NW 1/2 OF THE
CWA AS CONVECTION COULD BE DIURNALLY ENHANCED...THEN OVER THE NW 1/3
OF THE AREA ON MONDAY AHEAD OF AN ADVANCING CUTOFF LOW AND
ASSOCIATED TROUGH FORECAST TO MOVE INTO THE GREAT LAKES ON MONDAY.
FOR TEMPERATURES THURSDAY NIGHT-MONDAY A BLEND OF
MEX/MEN/EKD/ECE/ECM/WPC GUIDANCE WAS USED...WITH NAM 2-METER
TEMPERATURES MIXED IN AS WELL FOR THURSDAY NIGHT. LOWS ARE FORECAST
TO REMAIN ABOVE NORMAL IN THIS TIME FRAME WITH HIGHS NEAR TO
SLIGHTLY ABOVE NORMAL.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
OFFSHORE BROAD HIGH PRESSURE PERSISTS THROUGH THE TAF PERIOD.
MAINLY VFR WITH ANY LOWER CATEGORIES BEING DUE TO PATCHY FOG/LOW
STRATUS OR SHOWER/THUNDERSTORM ACTIVITY. THE SHOWER/THUNDERSTORM
ACTIVITY WILL BE LOW COVERAGE PRIMARILY N/W OF CITY TERMINALS.
THE PATCHY FOG/LOW STRATUS WILL BE PRIMARILY LATE TONIGHT INTO
WEDNESDAY MORNING. S FLOW UNDER 10 KT INCREASES TO 10-15 KT THIS
AFTERNOON BEFORE DIMINISHING AGAIN TONIGHT.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT:
HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. WINDS
COULD GUST OCCASIONALLY UP TO 20 KT LATE THIS AFTERNOON AND EARLY
THIS EVENING.
KLGA FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. WINDS
COULD GUST OCCASIONALLY UP TO 20 KT THIS AFTERNOON.
KEWR FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. WINDS
COULD GUST OCCASIONALLY UP TO 20 KT THIS AFTERNOON.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH
IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. WINDS
COULD GUST OCCASIONALLY UP TO 15 KT THIS AFTERNOON.
KHPN FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. WINDS
COULD GUST OCCASIONALLY UP TO 15 KT THIS AFTERNOON.
KISP FCSTER COMMENTS: MODERATE CONFIDENCE IN FORECAST. WINDS
COULD GUST OCCASIONALLY UP TO 20 KT THIS AFTERNOON.
.OUTLOOK FOR 12Z WEDNESDAY THROUGH SATURDAY...
.WED...ISOLD-SCT AFTN SHRA/TSTM POSSIBLE MAINLY FROM CITY
TERMINALS ON N/W. S-SW WINDS G15-20KT. MVFR OR LOWER POSSIBLE.
.WED NIGHT-THU...MVFR OR LOWER POSSIBLE WITH A LOW CHC OF SHRA.
RELATIVELY HIGHER CHC THU NEAR CITY TERMINALS AND N/W.
.THU NIGHT-FRI NIGHT...MVFR OR LOWER POSSIBLE IN SHRA/TSTMS.
.SATURDAY...MVFR POSSIBLE WITH A CHANCE OF SHRA/TSTMS.
&&
.MARINE...
MADE MINOR CHANGES THIS UPDATE TO REFLECT THE LATEST TRENDS IN
OBSERVATIONS AND GUIDANCE. THE FORECAST APPEARS ON TRACK.
PREVAILING WINDS AND SEAS SHOULD REMAIN BELOW SCA CRITERIA THROUGH
WEDNESDAY...BUT A FEW GUSTS TO 25 KT WILL BE POSSIBLE NEAR THE NY
HARBOR ENTRANCE LATE THIS AFTERNOON/EARLY EVENING.
A RELAXED PRESSURE GRADIENT OVER THE REGION WILL KEEP WINDS AT 10 KT
OR LESS WEDNESDAY NIGHT THROUGH SATURDAY. SEAS ON THE COASTAL OCEAN
WATERS SHOULD BE 3 FT OR LESS AND ON THE NON-OCEAN WATERS 1 FT OR
LESS IN THIS TIME FRAME AS A RESULT.
&&
.HYDROLOGY...
ALTHOUGH SHOWER/THUNDERSTORM COVERAGE IS EXPECTED TO BE
RELATIVELY SPARSE TODAY...ANYTHING THAT FORMS WILL LIKELY REMAIN
NEARLY STATIONARY OR MOVE VERY SLOWLY...WITH POTENTIAL TO DUMP A
QUICK ISOLATED 1-2 INCHES OF RAIN. LOCALIZED FLASH FLOODING MAINLY
FOR URBAN AREAS IS POSSIBLE...BUT AGAIN...COVERAGE AND OVERALL
CHANCES OF RAINFALL ARE TOO LOW FOR CONSIDERATION OF A WATCH.
FOR WEDNESDAY...SCATTERED HEAVY SHOWERS AND THUNDERSTORMS MAY
CAUSE MAINLY MINOR URBAN FLOODING.
NO SIGNIFICANT WIDESPREAD PRECIPITATION IS EXPECTED
WEDNESDAY NIGHT AND THURSDAY.
FOR NOW FORECASTING 2/10 TO AROUND 1 INCH OF RAIN THURSDAY NIGHT
AND FRIDAY...WITH HIGHEST AMOUNTS OVER NW ZONES AND LOWEST AMOUNTS
OVER FAR E ZONES. WITH STORM MOTION FORECAST TO BE 5 KT OR
LESS...AND PRECIPITABLE WATERS FORECAST ON AVERAGE TO BE BETWEEN
1.5-2 INCHES THURSDAY NIGHT AND FRIDAY (WITH QUITE A BIT OF
DISCREPANCY BETWEEN INDIVIDUAL MODELS WITH THE NAM GOING BELOW 1.5
INCHES AND THE GFS ABOVE 2 INCHES)...THERE IS THE POTENTIAL FOR
ANY STRONGER STORM TO PRODUCE LOCALLY HEAVY RAINFALL. SINCE STORMS
ARE FORECAST TO BE SLOW MOVING...THERE IS THE POTENTIAL FOR
LOCALIZED MINOR URBAN/POOR DRAINAGE FLOODING.
IF PRECIPITABLE WATERS END UP BEING TOWARDS THE HIGHER END OF THE
RANGE...ESPECIALLY IF THE GFS ENDS UP BEING CORRECT...THEN THERE
WOULD BE THE POTENTIAL FOR LOCALIZED FLASH FLOODING AS
WELL...ESPECIALLY IN URBAN AREAS. CONFIDENCE IN WIDESPREAD FLASH
FLOODING CURRENTLY NOT HIGH ENOUGH TO MENTION IN THE HWO...WITH
LARGE DIFFERENCES IN FORECAST PRECIPITABLE WATERS BEING THE
LIMITING FACTOR.
WHILE THE MAIN THREAT FOR LOCALLY HEAVY RAINFALL IS THURSDAY NIGHT
AND FRIDAY...IT IS POSSIBLE THE THREAT COULD LINGER INTO FRIDAY
NIGHT DEPENDING ON EXACTLY HOW FAST THE COLD FRONT SLIDES TO THE
EAST.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JC/MALOIT
NEAR TERM...MALOIT/JC
SHORT TERM...JC
LONG TERM...MALOIT
AVIATION...JM
MARINE...JC/MALOIT
HYDROLOGY...JC/MALOIT
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
623 AM EDT TUE AUG 18 2015
.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL TRACK ACROSS THE CENTRAL PLAINS TODAY
INTO TONIGHT, THEN ACROSS THE UPPER GREAT LAKES REGION WEDNESDAY. AS
THIS LOW MOVES INTO CANADA THURSDAY, ITS ASSOCIATED COLD FRONT IS
FORECAST TO SLOWLY MOVE THROUGH OUR AREA THURSDAY NIGHT AND FRIDAY.
HIGH PRESSURE THEN BUILDS INTO OUR AREA DURING THE WEEKEND, WITH THE
NEXT COLD FRONT ARRIVING LATE MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE GFS INITIALIZATION AT 500MB LOOKED CLOSER THAN THE WRF-NMMB.
AT 850MB, THE INITIALIZATION ERRORS BY BOTH MODELS WERE GENERALLY
1C TOO COLD, WHILE AT 925MB IT WAS A SMATTERING OF 1C ERRORS IN
BOTH DIRECTIONS. ANOTHER NIGHT, A DP/DT IN THE OPPOSITE DIRECTION
AGAIN AS THE MODEL PROGRESSIVE TREND IS SLOWER.
IN THE NEAR TERM ITS A RACE BETWEEN INSTABILITY BEING TAPPED AND
DRIER AIR ARRIVING FROM THE DELMARVA PENINSULA WATERS. COMPLICATING
THE PICTURE FURTHER IS THE SHORT WAVE OVER WEST VIRGINIA AND THE
NEVER SAY DIE TRULY ISOLATED SHOWERS CURRENTLY IN OUR CWA. WHEN ALL
OF THE MEASURABLE VOTES ARE TALLIED THE PAST TWO DAYS, WE WERE VERY
CLOSE TO OUR 15 PCT POP MENTION THRESHOLD ACROSS OUR CWA BOTH DAYS.
BUT OVERALL THERE WAS MORE THAN WHAT WE EXPECTED EVEN IN TERMS OF
ISOLATED PCPN AND THIS SWAYED OUR DECISION FOR TODAY GIVEN WE ARE
IN THE SAME REGIME.
THUS WE ARE BANKING ON A HAT TRICK OF OVERPERFORMANCE VS THE
CONVECTING MESOSCALE MODELS WHICH ONCE AGAIN HAVE NEXT TO NOTHING.
THE SHORT WAVE BANKING AGAINST THE NJ SHORE THAT CAUSED THE
ENHANCED SHOWERS IN PARTS OF THE LOWER RARITAN AND PASSAIC BASINS
IS PREDICTED TO WEAKEN. HRRR HAD A COUPLE OF GOOD RUNS INITIATING
THE PCPN AND IT HAS IT THRU OR DISSIPATED BY 12Z.
THEN IT WOULD APPEAR THE NEXT POTENTIAL ROUND OF ISOLATED
PRECIPITATION SHOULD COMMENCE AROUND NOON TIME. IF PCPN WERE TO
OCCUR IN THE SERN PART OF OUR CWA, HIEST CHANCE WOULD BE THIS
MORNING WHEN MIXED LAYER CAPES ABOVE THE CIN ARE MAXIMIZED. AFTER
THAT ITS ROUGHLY NORTH OF THE PA TURNPIKE AND NORTHWEST OF I287 IN
NJ AS OUR DIVIDING LINE BETWEEN POPS AND NONE AS DRIER AIR ALOFT
ARRIVES.
LATE IN THE DAY, THE ADDED ELEMENT OF THE WESTVA SHORT WAVE BRINGS
POPS INTO DELMARVA. LIKE THE PAST TWO DAYS, PREDICTED BULK SHEAR
VALUES ARE LESS THAN 15 KNOTS. MID LEVEL LAPSE RATES ARE SLIGHTLY
BETTER, AROUND 5.5C/KM, BUT THAT BAR WAS SET VERY LOW ALSO. A REPEAT
OF THE PAST TWO DAYS WITH SLOW MOVING SHOWERS AND TSTMS, ONE OR TWO
OF WHICH MIGHT REQUIRE A FLOOD ADVISORY. STRONG WIND GUSTS AND
SEVERE POTENTIAL ARE MUCH LOWER THAN AVERAGE FOR AN AUGUST AFTERNOON
WITH TSTMS AROUND.
TEMPERATURES, ANOTHER DAY OF 90S FOR A CHUNK OF OUR CWA. BUT, THE
AIR MASS IS SLIGHTLY COOLER AND IN QUOTES COOLER AIR IS WRAPPING
AROUND THE OFFSHORE HIGH INTO OUR AREA. IN ADDITION, THE SKY WILL
NOT BE AS CLEAN WITH UPSTREAM CIRRUS HEADING OUR WAY AND ALTOCU
AROUND EARLY THIS MORNING. THE GFS PREDICTED 850MB TEMP DROP THIS
AFTERNOON HAS NO UPSTREAM HISTORY. IN GENERAL MAX TEMPS HAVE BEEN
AVERAGING AROUND 2F HIGHER THAN STAT GUIDANCE THE PAST COUPLE OF
DAYS AND WE USED THIS FORMULA AGAIN TODAY.
MAX TEMPS ABOUT A DEGREE OR TWO COOLER THAN YESTERDAY COUPLED WITH
SIMILAR TO SLIGHTLY HIGHER DEW POINTS SHOULD RESULT IN HEAT INDEX
VALUES VERY SIMILAR TO YESTERDAY, PEAKING IN THE MID 90S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
THE SHORT WAVES HAVE TO RUN THEIR COURSE OVERNIGHT. WITH THE RIDGE
AXIS GONE, THERE IS NOTHING TO IMPEDE THEIR MOTION INTO OUR CWA.
THE WEAKENING TREND LOOKS REASONABLE GIVEN THAT INSTABILITY IS NOT
PREDICTED TO INCREASE OVERNIGHT. STILL A PAIR OF SHORT WAVES, THE
ONE IN WEST VIRGINIA AND A SECOND FARTHER WEST IN THE OHIO VALLEY
SHOULD KEEP SOME LOW CHANCE OF SHOWERS AND TSTMS GOING FOR MOST OF
THE NIGHT.
THE MOISTENING TREND CONTINUING WITH THE SOUTHEAST TO SOUTH FLOW AND
MODEL SOUNDINGS ARE SUGGESTING LOW CLOUDS MAY FORM OVERNIGHT. THIS
SHOULD KEEP MIN TEMPS RELATIVELY HIGHER. THE INCREASING DEW POINTS
WILL LIKELY ACCOMPLISH THAT WHETHER THE CLOUDS FORM OR NOT. MINS NOT
THAT FAR FROM STAT GUIDANCE.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
THE SYNOPTIC SETUP IS COMPRISED OF AN UPPER-LEVEL RIDGE THAT HANGS
ON FOR AWHILE IN THE WESTERN ATLANTIC TOWARD THE CANADIAN MARITIMES,
MEANWHILE A STRONG UPPER-LEVEL TROUGH/CLOSED LOW MOVES ACROSS THE
NORTHERN PLAINS TO THE GREAT LAKES WEDNESDAY. THIS FEATURE LOOKS TO
BE DEFLECTED INTO CANADA AS THE UPPER-LEVEL RIDGE HOLDS INTO THE
CANADIAN MARITIMES. THE RIDGE IS FORECAST TO GRADUALLY WEAKEN WITH A
BROAD TROUGH FROM THE PLAINS TO THE GREAT LAKES. THIS MAY THEN
AMPLIFY FROM THE MIDWEST AND GREAT LAKES OVER THE WEEKEND, WHICH
DRIVES A COLD FRONT INTO OUR AREA LATE MONDAY. A SLOW MOVING COLD
FRONT HOWEVER LATE THURSDAY AND FRIDAY MAY RESULT IN LOCALLY HEAVY
RAIN GIVEN PW VALUES SURGING TO AROUND 2 INCHES. WE USED A MODEL
BLEND FOR WEDNESDAY INTO FRIDAY, THEN BLENDED IN THE 00Z WPC GUIDANCE
WITH CONTINUITY.
FOR WEDNESDAY...HIGH PRESSURE TO OUR EAST WILL MAINTAIN A SOUTHERLY
FLOW OF WARM AND MOIST AIR ACROSS THE AREA. AN UPPER-LEVEL TROUGH
CLOSING OFF IN THE MIDWEST TO THE UPPER GREAT LAKES WILL DRIVE A
COLD FRONT EASTWARD. A WEAK WARM FRONT COMBINED WITH SOME LIFT MAY
RESULT IN SOME CONVECTION ESPECIALLY FOR THE INLAND AREAS. THE
COVERAGE DOES NOT APPEAR TO BE MUCH WITH MOST OF THE BETTER LIFT
REMAINING TO OUR WEST. THEREFORE, WE KEPT SLIGHT CHC TO LOW CHC POPS
IN FOR THE IDEA OF ISOLATED TO SCATTERED CONVECTION DEVELOPING. MORE
CLOUDINESS AND A SOUTHEASTERLY LOW-LEVEL FLOW SHOULD RESULT IN SOME
COOLING, HOWEVER IT WILL BE HUMID.
FOR THURSDAY AND FRIDAY...A CLOSED LOW IS FORECAST TO MOVE INTO
CANADA AS RIDGING HOLDS INTO THE CANADIAN MARITIMES. THIS WILL TAKE
THE SURFACE LOW WELL TO OUR NORTHWEST WITH ITS ASSOCIATED COLD FRONT
SLOWLY MOVING THROUGH THURSDAY NIGHT AND FRIDAY. THERE IS PLENTY OF
MOISTURE IN PLACE WITH PW VALUES SURGING TO AROUND 2 INCHES, HOWEVER
THE BULK OF THE LARGE SCALE LIFT IS FORECAST TO BE REMOVED FROM OUR
AREA DUE TO THE UPPER-LEVEL SYSTEM TRACKING SO FAR TO OUR WEST AND
NORTH.
A CYCLONICALLY CURVED 500 MB JET IS FORECAST TO LIFT UP THE OHIO
VALLEY AND ACROSS WESTERN/CENTRAL NEW YORK AND PENNSYLVANIA. THIS
PLACES OUR WESTERN ZONES CLOSE TO THE ENTRANCE REGION FOR A TIME
LATE THURSDAY INTO FRIDAY MORNING. THIS TIMING MAY CHANGE THOUGH
DEPENDING ON THE ACTUAL SPEED OF THE ENTIRE SYSTEM. AS A RESULT,
SOME ENHANCED LIFT MAY GLANCE OUR AREA INTO FRIDAY WITH A LINE OR
BROKEN LINE OF HEAVY RAIN PRODUCING CONVECTION POTENTIALLY AIDED BY
A FRONTAL CONVERGENCE ZONE. THE LOW-LEVEL FLOW IS FROM THE SOUTHEAST
BUT GENERALLY ON THE LIGHTER SIDE, WHICH COULD FAVOR SOME
BACKBUILDING/TRAINING CONVECTION WITHIN AN ENVIRONMENT CHARACTERIZED
BY A TALL AND THIN CAPE PROFILE. THE DETAILS ARE NOT ALL THAT CLEAR
THOUGH AS WE HAVE SOME CONCERN THE CONVECTION COULD BE MORE LIMITED
GIVEN THE MAIN DYNAMICS PASSING WELL TO OUR WEST AND NORTH. HOWEVER,
THERE STILL REMAINS THE POTENTIAL FOR INCREASING CONVECTIVE COVERAGE
WITH LOCALLY VERY HEAVY RAINFALL. A MENTION WILL REMAIN IN THE
HAZARDOUS WEATHER OUTLOOK.
FOR SATURDAY AND SUNDAY...A COLD FRONT SHOULD BE JUST OFFSHORE TO
START SATURDAY WITH THE FRONT POSSIBLY STALLING AS THE PARENT UPPER-
LEVEL TROUGH LIFTS WELL UP INTO CANADA. THIS ALLOWS SURFACE HIGH
PRESSURE TO BUILD INTO THE AREA, ALTHOUGH IT SHOULD WEAKEN SOME
DURING SUNDAY AS IT STARTS TO SHIFT OFFSHORE. SINCE WE ARE REMOVED
FROM THE AFOREMENTIONED MAIN UPPER-LEVEL TROUGH BUT THE SURFACE
FRONT EASES OFFSHORE, WE HAVE SOME SLIGHT CHC TO LOW CHC POPS ACROSS
THE EAST SATURDAY, THEN SLIGHT CHC EVERYWHERE ON SUNDAY. OVERALL,
THE WEEKEND FOR MOST ATTM LOOKS TO BE DRY. A COOLER AIRMASS IS
EXPECTED TO SETTLE IN FOLLOWING THE FRONTAL PASSAGE, WITH SOME
LOWERING OF THE DEW POINTS ESPECIALLY THE FARTHER INLAND ONE GOES.
FOR MONDAY...ANOTHER AMPLIFYING UPPER-LEVEL TROUGH IS FORECAST TO
CRUISE ACROSS THE NORTHERN PLAINS TO THE GREAT LAKES. THIS WILL
DRIVE LOW PRESSURE MAINLY NORTH OF THE GREAT LAKES, AND ITS
ASSOCIATED COLD FRONT ARRIVES IN OUR AREA LATE. SOME CONVECTION
SHOULD ACCOMPANY THE FRONT, HOWEVER ONCE AGAIN THE MAIN FORCING WITH
THE PARENT UPPER-LEVEL TROUGH MAY END UP BEING REMOVED FROM OUR
AREA. THIS MAY LIMIT THE CONVECTIVE CHCS FOR OUR AREA AS A RESULT.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
THROUGH 14Z TODAY...A STRATUS DECK NEAR THE MVFR/IFR THRESHOLD
THAT FORMED WEST AND SOUTHWEST OF KPHL HAS EXPANDED AND IS
SPREADING INTO THE KPHL METRO AIRPORTS. EXPECTATIONS ARE THAT THIS
DECK SHOULD DISSIPATE BY 13Z OR 14Z. ANY MVFR TO LOCALLY IFR FOG
SHOULD BE GONE BY 12Z. ABOVE THESE CLOUDS AND RESTRICTIONS
GENERALLY JUST A FEW MID AND HIGH LEVEL CLOUDS WILL BE AROUND.
WINDS WILL BE SOUTH OR LIGHT AND VARIABLE.
AFTER 14Z THIS MORNING...VFR WITH A SOUTH WIND INCREASING TO 5 TO
10 KNOTS. FEW TO SCATTERED CUMULUS AT 5K TO 6K SHOULD START
FORMING.
THIS AFTERNOON INTO EARLY EVENING...FEW TO SCATTERED CUMULUS
CONTINUING WITH CIRRUS ABOVE. SOUTH TO SOUTHEAST WINDS AVERAGING
CLOSER TO 10 KNOTS. LIKE THE PAST TWO DAYS, WIDELY SCATTERED
SHWRS AND TSTMS ARE EXPECTED TO DEVELOP, BUT CONFIDENCE ABOUT THEM
AFFECTING ANY OF THE TERMINALS IS LOW AND NOT INCLUDED. GREATEST
COVERAGE SHOULD BE AT NORTHWEST AIRPORTS.
OVERNIGHT...ONE OF OUR GUIDANCE MODELS IS PREDICTING IFR CIGS TO
FORM AT THE TERMINALS. MOST OTHER GUIDANCE INCLUDING SOME OF THE
NEWER EXPERIMENTAL MODELS WE ARE VIEWING STILL DO NOT. IFR CIGS
ARE PREDICTED NORTH OF KABE AND KTTN.
INITIAL THOUGHT FOR 12Z TAFS IS TO FOLLOW IDEA OF LOWEST (MVFR) CIGS
AT THE TERMINALS WITH THE MOST UPSLOPE/SOUTH FLOW (KABE, KRDG AND
KTTN). OTHER TERMINALS, WE KEPT CIGS MAINLY AT VFR LEVELS.
FARTHER UPSLOPE AIRPORTS IN THE POCONOS AND NORTHWEST NEW JERSEY
MIGHT HAVE IFR CIGS. CONFIDENCE ABOUT IFR CIG OCCURRING AT THE
TERMINALS AND KPHL IS LOW. WE WILL ALSO BRING IN SOME LIGHT FOG
(MVFR RESTRICTIONS) TO MOST NON URBAN TERMINALS BY WEDNESDAY
MORNING. SOUTHEAST WINDS SHOULD AVERAGE 5 KNOTS OR LESS.
OUTLOOK...
WEDNESDAY...VFR OVERALL. THERE COULD BE SOME MVFR/IFR CONDITIONS TO
START DUE TO LOW CLOUDS OR FOG, THEN POSSIBLY LOCALLY AGAIN THROUGH
THE DAY AND EVENING WITH A FEW SHOWERS OR THUNDERSTORMS.
THURSDAY AND FRIDAY...SHOWERS AND THUNDERSTORMS MAY BECOME NUMEROUS
FOR A TIME WITH A SLOW MOVING COLD FRONT. THIS WILL RESULT IN TIMES
OF MVFR/IFR CONDITIONS. A WIND SHIFT TO THE NORTHWEST SHOULD OCCUR
WITH THE PASSAGE OF A COLD FRONT THURSDAY NIGHT AND FRIDAY.
SATURDAY...VFR OVERALL AS HIGH PRESSURE BUILDS IN.
&&
.MARINE...
SUB SMALL CRAFT ADVISORY CONDITIONS ARE PREDICTED TO CONTINUE TODAY
AND TONIGHT. HOWEVER, A STRONGER SOUTHERLY GRADIENT (BECOMING SE
IN DELAWARE BAY) WILL BRING WIND GUSTS TO AROUND 20 KNOTS LATER THIS
AFTERNOON INTO EVENING BEFORE DECREASING AGAIN. WAVE WATCH GUIDANCE
WHICH NORMALLY IS QUITE BULLISH WITH SOUTHERLY FLOW SEAS REMAINS
SUBDUED WITH SUB SMALL CRAFT ADVISORY SEAS.
OUTLOOK...
WEDNESDAY THROUGH FRIDAY...THE WINDS AND SEAS ARE ANTICIPATED TO
REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA AS A COLD FRONT SLOWLY
CROSSES THE AREA. A FEW THUNDERSTORMS COULD PRODUCE A LOCALLY STRONG
WIND GUST MAINLY LATE THURSDAY AND FRIDAY. THE PASSAGE OF THE COLD
FRONT FRIDAY SHOULD RESULT IN THE WINDS SHIFTING TO NORTHERLY.
SATURDAY...THE WINDS AND SEAS SHOULD REMAIN BELOW SMALL CRAFT
ADVISORY CRITERIA AS HIGH PRESSURE BUILDS IN FROM THE NORTHWEST.
&&
.RIP CURRENTS...
THE IN HOUSE OFFICE REGRESSION EQUATION FOR RIP CURRENT RISKS
CAME UP WITH MODERATE FOR TODAY ALONG THE NJ COAST AND LOW FOR
THE DELAWARE COAST. GIVEN THAT WINDS TODAY ARE EXPECTED TO BE
SLIGHTLY STRONGER AND MORE FROM THE SOUTHEAST, WE WILL USE THIS
RESULT VS THE GFE OUTPUT WHICH WAS LOW ACROSS THE BOARD.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...GORSE
NEAR TERM...GIGI
SHORT TERM...GIGI
LONG TERM...GORSE
AVIATION...GIGI/GORSE
MARINE...GIGI/GORSE
RIP CURRENTS...
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
549 AM EDT TUE AUG 18 2015
.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL TRACK ACROSS THE CENTRAL PLAINS TODAY
INTO TONIGHT, THEN ACROSS THE UPPER GREAT LAKES REGION WEDNESDAY. AS
THIS LOW MOVES INTO CANADA THURSDAY, ITS ASSOCIATED COLD FRONT IS
FORECAST TO SLOWLY MOVE THROUGH OUR AREA THURSDAY NIGHT AND FRIDAY.
HIGH PRESSURE THEN BUILDS INTO OUR AREA DURING THE WEEKEND, WITH THE
NEXT COLD FRONT ARRIVING LATE MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE GFS INITIALIZATION AT 500MB LOOKED CLOSER THAN THE WRF-NMMB.
AT 850MB, THE INITIALIZATION ERRORS BY BOTH MODELS WERE GENERALLY
1C TOO COLD, WHILE AT 925MB IT WAS A SMATTERING OF 1C ERRORS IN
BOTH DIRECTIONS. ANOTHER NIGHT, A DP/DT IN THE OPPOSITE DIRECTION
AGAIN AS THE MODEL PROGRESSIVE TREND IS SLOWER.
IN THE NEAR TERM ITS A RACE BETWEEN INSTABILITY BEING TAPPED AND
DRIER AIR ARRIVING FROM THE DELMARVA PENINSULA WATERS. COMPLICATING
THE PICTURE FURTHER IS THE SHORT WAVE OVER WEST VIRGINIA AND THE
NEVER SAY DIE TRULY ISOLATED SHOWERS CURRENTLY IN OUR CWA. WHEN ALL
OF THE MEASURABLE VOTES ARE TALLIED THE PAST TWO DAYS, WE WERE VERY
CLOSE TO OUR 15 PCT POP MENTION THRESHOLD ACROSS OUR CWA BOTH DAYS.
BUT OVERALL THERE WAS MORE THAN WHAT WE EXPECTED EVEN IN TERMS OF
ISOLATED PCPN AND THIS SWAYED OUR DECISION FOR TODAY GIVEN WE ARE
IN THE SAME REGIME.
THUS WE ARE BANKING ON A HAT TRICK OF OVERPERFORMANCE VS THE
CONVECTING MESOSCALE MODELS WHICH ONCE AGAIN HAVE NEXT TO NOTHING.
THE SHORT WAVE BANKING AGAINST THE NJ SHORE THAT CAUSED THE
ENHANCED SHOWERS IN PARTS OF THE LOWER RARITAN AND PASSAIC BASINS
IS PREDICTED TO WEAKEN. HRRR HAD A COUPLE OF GOOD RUNS INITIATING
THE PCPN AND IT HAS IT THRU OR DISSIPATED BY 12Z.
THEN IT WOULD APPEAR THE NEXT POTENTIAL ROUND OF ISOLATED
PRECIPITATION SHOULD COMMENCE AROUND NOON TIME. IF PCPN WERE TO
OCCUR IN THE SERN PART OF OUR CWA, HIEST CHANCE WOULD BE THIS
MORNING WHEN MIXED LAYER CAPES ABOVE THE CIN ARE MAXIMIZED. AFTER
THAT ITS ROUGHLY NORTH OF THE PA TURNPIKE AND NORTHWEST OF I287 IN
NJ AS OUR DIVIDING LINE BETWEEN POPS AND NONE AS DRIER AIR ALOFT
ARRIVES.
LATE IN THE DAY, THE ADDED ELEMENT OF THE WESTVA SHORT WAVE BRINGS
POPS INTO DELMARVA. LIKE THE PAST TWO DAYS, PREDICTED BULK SHEAR
VALUES ARE LESS THAN 15 KNOTS. MID LEVEL LAPSE RATES ARE SLIGHTLY
BETTER, AROUND 5.5C/KM, BUT THAT BAR WAS SET VERY LOW ALSO. A REPEAT
OF THE PAST TWO DAYS WITH SLOW MOVING SHOWERS AND TSTMS, ONE OR TWO
OF WHICH MIGHT REQUIRE A FLOOD ADVISORY. STRONG WIND GUSTS AND
SEVERE POTENTIAL ARE MUCH LOWER THAN AVERAGE FOR AN AUGUST AFTERNOON
WITH TSTMS AROUND.
TEMPERATURES, ANOTHER DAY OF 90S FOR A CHUNK OF OUR CWA. BUT, THE
AIR MASS IS SLIGHTLY COOLER AND IN QUOTES COOLER AIR IS WRAPPING
AROUND THE OFFSHORE HIGH INTO OUR AREA. IN ADDITION, THE SKY WILL
NOT BE AS CLEAN WITH UPSTREAM CIRRUS HEADING OUR WAY AND ALTOCU
AROUND EARLY THIS MORNING. THE GFS PREDICTED 850MB TEMP DROP THIS
AFTERNOON HAS NO UPSTREAM HISTORY. IN GENERAL MAX TEMPS HAVE BEEN
AVERAGING AROUND 2F HIGHER THAN STAT GUIDANCE THE PAST COUPLE OF
DAYS AND WE USED THIS FORMULA AGAIN TODAY.
MAX TEMPS ABOUT A DEGREE OR TWO COOLER THAN YESTERDAY COUPLED WITH
SIMILAR TO SLIGHTLY HIGHER DEW POINTS SHOULD RESULT IN HEAT INDEX
VALUES VERY SIMILAR TO YESTERDAY, PEAKING IN THE MID 90S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
THE SHORT WAVES HAVE TO RUN THEIR COURSE OVERNIGHT. WITH THE RIDGE
AXIS GONE, THERE IS NOTHING TO IMPEDE THEIR MOTION INTO OUR CWA.
THE WEAKENING TREND LOOKS REASONABLE GIVEN THAT INSTABILITY IS NOT
PREDICTED TO INCREASE OVERNIGHT. STILL A PAIR OF SHORT WAVES, THE
ONE IN WEST VIRGINIA AND A SECOND FARTHER WEST IN THE OHIO VALLEY
SHOULD KEEP SOME LOW CHANCE OF SHOWERS AND TSTMS GOING FOR MOST OF
THE NIGHT.
THE MOISTENING TREND CONTINUING WITH THE SOUTHEAST TO SOUTH FLOW AND
MODEL SOUNDINGS ARE SUGGESTING LOW CLOUDS MAY FORM OVERNIGHT. THIS
SHOULD KEEP MIN TEMPS RELATIVELY HIGHER. THE INCREASING DEW POINTS
WILL LIKELY ACCOMPLISH THAT WHETHER THE CLOUDS FORM OR NOT. MINS NOT
THAT FAR FROM STAT GUIDANCE.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
THE SYNOPTIC SETUP IS COMPRISED OF AN UPPER-LEVEL RIDGE THAT HANGS
ON FOR AWHILE IN THE WESTERN ATLANTIC TOWARD THE CANADIAN MARITIMES,
MEANWHILE A STRONG UPPER-LEVEL TROUGH/CLOSED LOW MOVES ACROSS THE
NORTHERN PLAINS TO THE GREAT LAKES WEDNESDAY. THIS FEATURE LOOKS TO
BE DEFLECTED INTO CANADA AS THE UPPER-LEVEL RIDGE HOLDS INTO THE
CANADIAN MARITIMES. THE RIDGE IS FORECAST TO GRADUALLY WEAKEN WITH A
BROAD TROUGH FROM THE PLAINS TO THE GREAT LAKES. THIS MAY THEN
AMPLIFY FROM THE MIDWEST AND GREAT LAKES OVER THE WEEKEND, WHICH
DRIVES A COLD FRONT INTO OUR AREA LATE MONDAY. A SLOW MOVING COLD
FRONT HOWEVER LATE THURSDAY AND FRIDAY MAY RESULT IN LOCALLY HEAVY
RAIN GIVEN PW VALUES SURGING TO AROUND 2 INCHES. WE USED A MODEL
BLEND FOR WEDNESDAY INTO FRIDAY, THEN BLENDED IN THE 00Z WPC GUIDANCE
WITH CONTINUITY.
FOR WEDNESDAY...HIGH PRESSURE TO OUR EAST WILL MAINTAIN A SOUTHERLY
FLOW OF WARM AND MOIST AIR ACROSS THE AREA. AN UPPER-LEVEL TROUGH
CLOSING OFF IN THE MIDWEST TO THE UPPER GREAT LAKES WILL DRIVE A
COLD FRONT EASTWARD. A WEAK WARM FRONT COMBINED WITH SOME LIFT MAY
RESULT IN SOME CONVECTION ESPECIALLY FOR THE INLAND AREAS. THE
COVERAGE DOES NOT APPEAR TO BE MUCH WITH MOST OF THE BETTER LIFT
REMAINING TO OUR WEST. THEREFORE, WE KEPT SLIGHT CHC TO LOW CHC POPS
IN FOR THE IDEA OF ISOLATED TO SCATTERED CONVECTION DEVELOPING. MORE
CLOUDINESS AND A SOUTHEASTERLY LOW-LEVEL FLOW SHOULD RESULT IN SOME
COOLING, HOWEVER IT WILL BE HUMID.
FOR THURSDAY AND FRIDAY...A CLOSED LOW IS FORECAST TO MOVE INTO
CANADA AS RIDGING HOLDS INTO THE CANADIAN MARITIMES. THIS WILL TAKE
THE SURFACE LOW WELL TO OUR NORTHWEST WITH ITS ASSOCIATED COLD FRONT
SLOWLY MOVING THROUGH THURSDAY NIGHT AND FRIDAY. THERE IS PLENTY OF
MOISTURE IN PLACE WITH PW VALUES SURGING TO AROUND 2 INCHES, HOWEVER
THE BULK OF THE LARGE SCALE LIFT IS FORECAST TO BE REMOVED FROM OUR
AREA DUE TO THE UPPER-LEVEL SYSTEM TRACKING SO FAR TO OUR WEST AND
NORTH.
A CYCLONICALLY CURVED 500 MB JET IS FORECAST TO LIFT UP THE OHIO
VALLEY AND ACROSS WESTERN/CENTRAL NEW YORK AND PENNSYLVANIA. THIS
PLACES OUR WESTERN ZONES CLOSE TO THE ENTRANCE REGION FOR A TIME
LATE THURSDAY INTO FRIDAY MORNING. THIS TIMING MAY CHANGE THOUGH
DEPENDING ON THE ACTUAL SPEED OF THE ENTIRE SYSTEM. AS A RESULT,
SOME ENHANCED LIFT MAY GLANCE OUR AREA INTO FRIDAY WITH A LINE OR
BROKEN LINE OF HEAVY RAIN PRODUCING CONVECTION POTENTIALLY AIDED BY
A FRONTAL CONVERGENCE ZONE. THE LOW-LEVEL FLOW IS FROM THE SOUTHEAST
BUT GENERALLY ON THE LIGHTER SIDE, WHICH COULD FAVOR SOME
BACKBUILDING/TRAINING CONVECTION WITHIN AN ENVIRONMENT CHARACTERIZED
BY A TALL AND THIN CAPE PROFILE. THE DETAILS ARE NOT ALL THAT CLEAR
THOUGH AS WE HAVE SOME CONCERN THE CONVECTION COULD BE MORE LIMITED
GIVEN THE MAIN DYNAMICS PASSING WELL TO OUR WEST AND NORTH. HOWEVER,
THERE STILL REMAINS THE POTENTIAL FOR INCREASING CONVECTIVE COVERAGE
WITH LOCALLY VERY HEAVY RAINFALL. A MENTION WILL REMAIN IN THE
HAZARDOUS WEATHER OUTLOOK.
FOR SATURDAY AND SUNDAY...A COLD FRONT SHOULD BE JUST OFFSHORE TO
START SATURDAY WITH THE FRONT POSSIBLY STALLING AS THE PARENT UPPER-
LEVEL TROUGH LIFTS WELL UP INTO CANADA. THIS ALLOWS SURFACE HIGH
PRESSURE TO BUILD INTO THE AREA, ALTHOUGH IT SHOULD WEAKEN SOME
DURING SUNDAY AS IT STARTS TO SHIFT OFFSHORE. SINCE WE ARE REMOVED
FROM THE AFOREMENTIONED MAIN UPPER-LEVEL TROUGH BUT THE SURFACE
FRONT EASES OFFSHORE, WE HAVE SOME SLIGHT CHC TO LOW CHC POPS ACROSS
THE EAST SATURDAY, THEN SLIGHT CHC EVERYWHERE ON SUNDAY. OVERALL,
THE WEEKEND FOR MOST ATTM LOOKS TO BE DRY. A COOLER AIRMASS IS
EXPECTED TO SETTLE IN FOLLOWING THE FRONTAL PASSAGE, WITH SOME
LOWERING OF THE DEW POINTS ESPECIALLY THE FARTHER INLAND ONE GOES.
FOR MONDAY...ANOTHER AMPLIFYING UPPER-LEVEL TROUGH IS FORECAST TO
CRUISE ACROSS THE NORTHERN PLAINS TO THE GREAT LAKES. THIS WILL
DRIVE LOW PRESSURE MAINLY NORTH OF THE GREAT LAKES, AND ITS
ASSOCIATED COLD FRONT ARRIVES IN OUR AREA LATE. SOME CONVECTION
SHOULD ACCOMPANY THE FRONT, HOWEVER ONCE AGAIN THE MAIN FORCING WITH
THE PARENT UPPER-LEVEL TROUGH MAY END UP BEING REMOVED FROM OUR
AREA. THIS MAY LIMIT THE CONVECTIVE CHCS FOR OUR AREA AS A RESULT.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
OTHER THAN SOME MVFR CONDITIONS AT MORE RURAL AIRPORTS AND
TERMINALS AROUND SUNRISE, 06Z TAFS ARE VFR.
THROUGH 12Z TODAY...A FEW LEFTOVER MID LEVEL CLOUDS (MAINLY
BEFORE SUNRISE) AND CIRRUS ABOVE THEM. WINDS WILL BE LIGHT
FROM THE SOUTH TO SOUTHEAST. SOME MVFR FOG POSSIBLE AT MORE
RURAL TERMINALS AND AIRPORTS WHERE PCPN OCCURRED ON MONDAY. WE
MADE SLIGHT ADJUSTMENTS TO FOG IN THE TAFS BASED ON HOW WIDE THE
CURRENT TEMPERATURE AND DEW POINT SPREADS ARE.
THIS MORNING...ANY FOG SHOULD BE GONE. VFR WITH A SOUTH WIND
INCREASING TO 5 TO 10 KNOTS. FEW TO SCATTERED CUMULUS AT 5K TO 6K
SHOULD START FORMING.
THIS AFTERNOON INTO EARLY EVENING...FEW TO SCATTERED CUMULUS
CONTINUING WITH CIRRUS ABOVE. SOUTH TO SOUTHEAST WINDS AVERAGING
CLOSER TO 10 KNOTS. LIKE THE PAST TWO DAYS, WIDELY SCATTERED
SHWRS AND TSTMS ARE EXPECTED TO DEVELOP, BUT CONFIDENCE ABOUT THEM
AFFECTING ANY OF THE TERMINALS IS LOW AND NOT INCLUDED. GREATEST
COVERAGE SHOULD BE AT NORTHWEST AIRPORTS.
OVERNIGHT...ONE OF OUR GUIDANCE MODELS IS PREDICTING IFR CIGS TO
FORM AT THE TERMINALS. MOST OTHER GUIDANCE INCLUDING SOME OF THE
NEWER EXPERIMENTAL MODELS WE ARE VIEWING STILL DO NOT. IFR CIGS
ARE PREDICTED NORTH OF KABE AND KTTN.
INITIAL THOUGHT FOR 12Z TAFS IS TO FOLLOW IDEA OF LOWEST (MVFR) CIGS
AT THE TERMINALS WITH THE MOST UPSLOPE/SOUTH FLOW (KABE, KRDG AND
KTTN). OTHER TERMINALS, WE KEPT CIGS MAINLY AT VFR LEVELS.
FARTHER UPSLOPE AIRPORTS IN THE POCONOS AND NORTHWEST NEW JERSEY
MIGHT HAVE IFR CIGS. CONFIDENCE ABOUT IFR CIG OCCURRING AT THE
TERMINALS AND KPHL IS LOW. WE WILL ALSO BRING IN SOME LIGHT FOG
(MVFR RESTRICTIONS) TO MOST NON URBAN TERMINALS BY WEDNESDAY
MORNING. SOUTHEAST WINDS SHOULD AVERAGE 5 KNOTS OR LESS.
OUTLOOK...
WEDNESDAY...VFR OVERALL. THERE COULD BE SOME MVFR/IFR CONDITIONS TO
START DUE TO LOW CLOUDS OR FOG, THEN POSSIBLY LOCALLY AGAIN THROUGH
THE DAY AND EVENING WITH A FEW SHOWERS OR THUNDERSTORMS.
THURSDAY AND FRIDAY...SHOWERS AND THUNDERSTORMS MAY BECOME NUMEROUS
FOR A TIME WITH A SLOW MOVING COLD FRONT. THIS WILL RESULT IN TIMES
OF MVFR/IFR CONDITIONS. A WIND SHIFT TO THE NORTHWEST SHOULD OCCUR
WITH THE PASSAGE OF A COLD FRONT THURSDAY NIGHT AND FRIDAY.
SATURDAY...VFR OVERALL AS HIGH PRESSURE BUILDS IN.
&&
.MARINE...
SUB SMALL CRAFT ADVISORY CONDITIONS ARE PREDICTED TO CONTINUE TODAY
AND TONIGHT. HOWEVER, A STRONGER SOUTHERLY GRADIENT (BECOMING SE
IN DELAWARE BAY) WILL BRING WIND GUSTS TO AROUND 20 KNOTS LATER THIS
AFTERNOON INTO EVENING BEFORE DECREASING AGAIN. WAVE WATCH GUIDANCE
WHICH NORMALLY IS QUITE BULLISH WITH SOUTHERLY FLOW SEAS REMAINS
SUBDUED WITH SUB SMALL CRAFT ADVISORY SEAS.
OUTLOOK...
WEDNESDAY THROUGH FRIDAY...THE WINDS AND SEAS ARE ANTICIPATED TO
REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA AS A COLD FRONT SLOWLY
CROSSES THE AREA. A FEW THUNDERSTORMS COULD PRODUCE A LOCALLY STRONG
WIND GUST MAINLY LATE THURSDAY AND FRIDAY. THE PASSAGE OF THE COLD
FRONT FRIDAY SHOULD RESULT IN THE WINDS SHIFTING TO NORTHERLY.
SATURDAY...THE WINDS AND SEAS SHOULD REMAIN BELOW SMALL CRAFT
ADVISORY CRITERIA AS HIGH PRESSURE BUILDS IN FROM THE NORTHWEST.
&&
.RIP CURRENTS...
THE IN HOUSE OFFICE REGRESSION EQUATION FOR RIP CURRENT RISKS
CAME UP WITH MODERATE FOR TODAY ALONG THE NJ COAST AND LOW FOR
THE DELAWARE COAST. GIVEN THAT WINDS TODAY ARE EXPECTED TO BE
SLIGHTLY STRONGER AND MORE FROM THE SOUTHEAST, WE WILL USE THIS
RESULT VS THE GFE OUTPUT WHICH WAS LOW ACROSS THE BOARD.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...GORSE
NEAR TERM...GIGI
SHORT TERM...GIGI
LONG TERM...GORSE
AVIATION...GIGI/GORSE
MARINE...GIGI/GORSE
RIP CURRENTS...
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
707 PM EDT TUE AUG 18 2015
.SYNOPSIS...
A MOIST FLOW CIRCULATING AROUND OFFSHORE HIGH PRESSURE WILL
PERSIST THROUGH MUCH OF THE WEEK. SCATTERED TO NUMEROUS SHOWERS
AND THUNDERSTORMS WILL OCCUR.
&&
.NEAR TERM /UNTIL 7 AM WEDNESDAY MORNING/...
THE SOUTHERLY FLOW CIRCULATING AROUND OFFSHORE HIGH PRESSURE HAS
RESULTED IN HIGH MOISTURE IN THE FORECAST AREA. PRECIPITABLE
WATER HAS INCREASED TO JUST OVER 2 INCHES. THE MOISTURE AND
HEATING HAS HELPED CAUSE SCATTERED SHOWERS AND THUNDERSTORMS. WEAK
LIFT AHEAD OF A WEAK MID-LEVEL SHORTWAVE TROUGH MAY RESULT IN MORE
WIDESPREAD COVERAGE LATER THIS EVENING. THE HRRR SHOWED
CONSIDERABLE COVERAGE ESPECIALLY IN THE CSRA AND SOUTH MIDLANDS
DURING THE 800 PM TO 1000 PM TIME FRAME. BELIEVE CLOUDINESS AND
SHOWERS WILL CONTINUE TO LIMIT INSTABILITY. THE SEVERE
THUNDERSTORM CHANCE IS LOW. SOME OF THE THUNDERSTORMS WILL HAVE
HEAVY DOWNPOURS BECAUSE OF THE HIGH PRECIPITABLE WATER. A STORM
MOTION NEAR 15 KNOTS SHOULD HELP KEEP RAIN FROM BECOMING EXCESSIVE
UNLESS TRAINING HAPPENS TO DEVELOP. CLOUDINESS FAVORS THE WARMER
TEMPERATURE GUIDANCE TONIGHT. FORECASTED LOWS MAINLY IN THE MIDDLE
70S.
&&
.SHORT TERM /7 AM WEDNESDAY MORNING THROUGH THURSDAY/...
A MOIST LOW-LEVEL SOUTHERLY FLOW CIRCULATING AROUND OFFSHORE
HIGH PRESSURE AND A SERIES OF MID-LEVEL SHORTWAVE TROUGHS IN A
FLAT FLOW WILL KEEP A THREAT OF SHOWERS AND THUNDERSTORMS ACROSS
THE REGION. PRECIPITABLE WATER WILL REMAIN HIGH WITH VALUES MAINLY
JUST ABOVE 2 INCHES. HEAVY DOWNPOURS MAY OCCUR WITH SOME OF THE
THUNDERSTORMS. USED THE GUIDANCE CONSENSUS FOR THE HIGH
TEMPERATURE FORECAST. USED THE WARMER LOW TEMPERATURE GUIDANCE
BECAUSE OF THE HIGH MOISTURE.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THE GFS AND ECMWF DISPLAY A DIFFUSE FRONT STALLED NEAR THE
FORECAST AREA EARLY IN THE MEDIUM-RANGE PERIOD. THE MODELS DISPLAY
ANOTHER FRONT LATE IN THE PERIOD. THE MODELS HAVE UPPER RIDGING
FRIDAY AND SATURDAY...WITH TROUGHING DURING THE REST OF THE
PERIOD. THE PATTERN SUPPORTS A CONTINUED CHANCE OF SHOWERS AND
THUNDERSTORMS. THE GFS ENSEMBLE MEAN PLUS GFS...ECMWF...AND EKD
MOS SUPPORT POPS OF MAINLY 20 TO 30 PERCENT. ABOVE NORMAL HIGH
TEMPERATURES SHOULD BE ASSOCIATED WITH THE UPPER RIDGING EARLY IN
THE PERIOD. THE REST OF THE PERIOD WILL LIKELY HAVE NEAR NORMAL
TEMPERATURES.
&&
.AVIATION /23Z TUESDAY THROUGH SUNDAY/...
SCATTERED SHOWERS HAVE DEVELOPED EARLY THIS AFTERNOON WITH DEEP
MOISTURE ACROSS THE AREA AND WEAK TO MODERATE INSTABILITY. THE
THREAT OF SHOWERS AND STORMS WILL CONTINUE THROUGH THIS EVENING
AND INTO TONIGHT WITH RESTRICTIONS POSSIBLE IN CONVECTION. HAVE
ADDED A TEMPO GROUP FROM 18Z-23Z TO ACCOUNT FOR SHOWERS AND
STORMS THAT AFFECT THE TERMINALS. WINDS WILL CONTINUE OUT OF THE
SOUTH THROUGH THIS EVENING AT 5 TO 10 KNOTS. MODELS SHOW POTENTIAL
FOR RESTRICTIONS EARLY WEDNESDAY MORNING ALTHOUGH A 25 TO 30 KNOT
LOW LEVEL JET SHOULD HELP LIMIT FOG DEVELOPMENT. CONFIDENCE IS TOO
LOW TO INCLUDE AT THIS TIME.
EXTENDED AVIATION OUTLOOK...A MOIST SOUTHERLY FLOW WILL CONTINUE
THROUGH THURSDAY. THERE WILL BE SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS. STRATUS AND FOG MAY OCCUR DURING THE EARLY MORNING
HOURS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
153 PM EDT TUE AUG 18 2015
.SYNOPSIS...
A MOIST FLOW CIRCULATING AROUND OFFSHORE HIGH PRESSURE WILL
PERSIST THROUGH MUCH OF THE WEEK. SCATTERED TO NUMEROUS SHOWERS
AND THUNDERSTORMS WILL OCCUR.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE SOUTHERLY FLOW CIRCULATING AROUND OFFSHORE HIGH PRESSURE HAS
RESULTED IN HIGH MOISTURE IN THE FORECAST AREA. PRECIPITABLE
WATER HAS INCREASED TO JUST OVER 2 INCHES. THE MOISTURE AND
HEATING HAS HELPED CAUSE SCATTERED SHOWERS AND THUNDERSTORMS EARLY
THIS AFTERNOON. WEAK LIFT AHEAD OF A WEAK MID-LEVEL SHORTWAVE
TROUGH MAY RESULT IN MORE WIDESPREAD COVERAGE LATE THIS AFTERNOON
INTO THE EVENING. THE HRRR SHOWED CONSIDERABLE COVERAGE ESPECIALLY
IN THE CSRA AND SOUTH MIDLANDS DURING THE 600 PM TO 1000 PM TIME
FRAME. BELIEVE CLOUDINESS AND SHOWERS WILL CONTINUE TO LIMIT
INSTABILITY. EARLY AFTERNOON SURFACE-BASED LI/S WERE -4 TO -5 WITH
A NEAR MOIST ADIABATIC LAPSE RATE. THE SEVERE THUNDERSTORM CHANCE
IS LOW. SOME OF THE THUNDERSTORMS WILL HAVE HEAVY DOWNPOURS
BECAUSE OF THE HIGH PRECIPITABLE WATER. A STORM MOTION NEAR 15
KNOTS SHOULD HELP KEEP RAIN FROM BECOMING EXCESSIVE UNLESS
TRAINING HAPPENS TO DEVELOP. CLOUDINESS FAVORS THE WARMER
TEMPERATURE GUIDANCE TONIGHT. FORECASTED LOWS MAINLY IN THE MIDDLE
70S.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
A MOIST LOW-LEVEL SOUTHERLY FLOW CIRCULATING AROUND OFFSHORE
HIGH PRESSURE AND A SERIES OF MID-LEVEL SHORTWAVE TROUGHS IN A
FLAT FLOW WILL KEEP A THREAT OF SHOWERS AND THUNDERSTORMS ACROSS
THE REGION. PRECIPITABLE WATER WILL REMAIN HIGH WITH VALUES MAINLY
JUST ABOVE 2 INCHES. HEAVY DOWNPOURS MAY OCCUR WITH SOME OF THE
THUNDERSTORMS. USED THE GUIDANCE CONSENSUS FOR THE HIGH
TEMPERATURE FORECAST. USED THE WARMER LOW TEMPERATURE GUIDANCE
BECAUSE OF THE HIGH MOISTURE.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
THE GFS AND ECMWF DISPLAY A DIFFUSE FRONT STALLED NEAR THE
FORECAST AREA EARLY IN THE MEDIUM-RANGE PERIOD. THE MODELS DISPLAY
ANOTHER FRONT LATE IN THE PERIOD. THE MODELS HAVE UPPER RIDGING
FRIDAY AND SATURDAY...WITH TROUGHING DURING THE REST OF THE
PERIOD. THE PATTERN SUPPORTS A CONTINUED CHANCE OF SHOWERS AND
THUNDERSTORMS. THE GFS ENSEMBLE MEAN PLUS GFS...ECMWF...AND EKD
MOS SUPPORT POPS OF MAINLY 20 TO 30 PERCENT. ABOVE NORMAL HIGH
TEMPERATURES SHOULD BE ASSOCIATED WITH THE UPPER RIDGING EARLY IN
THE PERIOD. THE REST OF THE PERIOD WILL LIKELY HAVE NEAR NORMAL
TEMPERATURES.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
SCATTERED SHOWERS HAVE DEVELOPED EARLY THIS AFTERNOON WITH DEEP
MOISTURE ACROSS THE AREA AND WEAK TO MODERATE INSTABILITY. THE
THREAT OF SHOWERS AND STORMS WILL CONTINUE THROUGH THIS EVENING
AND INTO TONIGHT WITH RESTRICTIONS POSSIBLE IN CONVECTION. HAVE
ADDED A TEMPO GROUP FROM 18Z-23Z TO ACCOUNT FOR SHOWERS AND
STORMS THAT AFFECT THE TERMINALS. WINDS WILL CONTINUE OUT OF THE
SOUTH THROUGH THIS EVENING AT 5 TO 10 KNOTS. MODELS SHOW POTENTIAL
FOR RESTRICTIONS EARLY WEDNESDAY MORNING ALTHOUGH A 25 TO 30 KNOT
LOW LEVEL JET SHOULD HELP LIMIT FOG DEVELOPMENT. CONFIDENCE IS TOO
LOW TO INCLUDE AT THIS TIME.
EXTENDED AVIATION OUTLOOK...A MOIST SOUTHERLY FLOW WILL CONTINUE
THROUGH THURSDAY. THERE WILL BE SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS. STRATUS AND FOG MAY OCCUR DURING THE EARLY MORNING
HOURS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
247 AM CDT TUE AUG 18 2015
.UPDATE...
THUNDERSTORMS CONTINUE TO FIRE THIS EVENING ALONG VARIOUS
BOUNDARIES. THE MAIN BOUNDARY EXTENDS FROM CENTRAL COOK COUNTY
THROUGH SOUTHERN DUPAGE INTO NORTHERN KENDALL. LATEST RAP
ANALYSIS INDICATES WE HAVE AROUND 500 J/KG OF CAPE TO WORK WITH
ALONG THE BOUNDARY SO ADDITIONAL ISOLATED TO SCATTERED STORMS ARE
POSSIBLE. THIS IS ESPECIALLY TRUE AS THE CURRENT STORMS PRODUCE
THEIR OWN BOUNDARIES. WITH LONG SKINNY CAPE VALUES IN FORECAST AND
00Z SOUNDINGS...EXPECTING ONLY THE STRONGEST STORMS TO PRODUCE
WIND GUSTS UP TO 50-60 MPH AND SMALL HAIL. ALL STORMS HOWEVER WILL
PRODUCE TORRENTIAL RAINFALL. THUS FAR MOST OF THE STORMS HAVE
EITHER BEEN MOVING OR WEAKENING JUST FAST ENOUGH TO AVOID FLOODING
ISSUES...BUT WILL CONTINUE TO MONITOR FOR TRAINING STORMS THAT
COULD PRODUCE FLASH FLOODING AND STANDING WATER.
STILL HAVE LOW CONFIDENCE IN EXACTLY HOW THE REST OF THE EVENING
WILL PROGRESS IN REGARDS TO STORMS. THE HRRR HAS DONE A VERY GOOD
JOB AT CAPTURING MOST OF WHAT HAS HAPPENED THUS FAR SO POP
FORECAST IS MOSTLY BASED OFF OF IT. EXPECTING MORE SCATTERED PULSE
CONVECTION ALONG THE OUTFLOW BOUNDARIES WHILE THE AREA OF
CONVECTION OVER WESTERN IL SPREADS EAST. THINKING THE STORMS OVER
WESTERN IL WILL WEAKEN AS THEY SHIFT EAST...BUT MORE STORMS WILL
PROBABLY FORM ALONG ANY OUTFLOW BOUNDARIES THE ORIGINAL STORMS
PRODUCE. IN ADDITION..A SHORTWAVE TROUGH IS OVER EASTERN IOWA SO
THINKING THAT WILL HELP FORCE WAVES OF CONVECTION THROUGH THE
NIGHT. HAD A VERY DIFFICULT TIME BEING MORE DETERMINISTIC IN MY
FORECAST SIMPLY BECAUSE OF THE MESOSCALE NATURE OF THE STORMS.
THEREFORE HAVE HIGH CONFIDENCE IN SCATTERED STORMS MAINLY
NORTHWEST OF A DE MOTTE THROUGH GIBSON CITY LINE...BUT LOW
CONFIDENCE IN EXACT TIMING AND COVERAGE AT ANY GIVEN TIME.
WITH THE AMPLE MOISTURE FROM THE STORMS...KEPT PATCHY FOG GOING
AFTER MIDNIGHT.
JEE
&&
.SHORT TERM...
340 PM CDT
THROUGH TUESDAY...
SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE THIS AFTERNOON. SEVERAL
OF THE STRONGER STORMS HAVE REPORTED WIND GUSTS AROUND 50 MPH AND
SMALL HAIL...ALONG WITH MODERATE TO HEAVY DOWNPOURS AND LIKELY
LOCALLY 1 INCH PLUS RAINFALL TOTALS.
THIS ACTIVITY IS COURTESY OF SEVERAL FEATURES...THE FIRST AN UPPER
LEVEL DISTURBANCE PUSHING INTO CENTRAL INDIANA WITH A WELL DEFINED
CLOSED CIRCULATION ON WATER VAPOR SATELLITE IMAGERY. THE SECOND IS A
COLD FRONT STRETCHED SOUTHWEST FROM NORTHERN LAKE MICHIGAN...THROUGH
CENTRAL WISCONSIN...THEN ORIENTED WEST-EAST IN MOST OF IOWA. SPC
MESOANALYSIS SHOWS MODERATE INSTABILITY WITH GOOD LOW LEVEL LAPSE
RATES...BUT POOR SHEAR...AND MODEST PW VALUES. THEREFORE LOCALLY
HEAVY RAINFALL AND GUSTY WINDS WILL REMAIN THE PREDOMINANT HAZARDS
THROUGH THE AFTERNOON AND EARLY EVENING HOURS. THESE STORMS ARE
PRODUCING OUTFLOW BOUNDARIES THAT WILL LOCALLY INCREASE
CONVERGENCE SUGGESTING SCATTERED STORMS REMAIN POSSIBLE AREA-WIDE.
WHILE THE CONVECTIVE EVOLUTION IS STILL A BIT UNCERTAIN...EXPECT A
DIURNAL DECREASE IN THE COVERAGE AWAY FROM THE COLD FRONT AS THE
UPPER LEVEL LOW ENTERS INDIANA EXITS TO THE EAST...ESPECIALLY INTO
EASTERN ILLINOIS AND NORTHWEST INDIANA. ADDITIONALLY...MODEL
GUIDANCE STALLS THE FRONT OUT ALONG A DUBUQUE TO ROCKFORD TO
MILWAUKEE LINE. THE NEXT SET OF DISTURBANCES PROPAGATE PARALLEL TO
THE COLD FRONTAL BOUNDARY...THUS HAVE RETAINED HIGHEST POPS IN NORTH
CENTRAL ILLINOIS AND ALONG THE WISCONSIN BORDER. A TRAILING
DISTURBANCE IN WESTERN IOWA WILL MOVE THROUGH THE AREA OVERNIGHT
WHICH MAY ALLOW SOME FURTHER EASTWARD PROGRESSION OVERNIGHT.
HEIGHT RISES AND SUBSIDENCE IN WAKE OF THE DEPARTING DISTURBANCE BUT
BROAD SW MOIST LOWER LEVEL FLOW SUPPORTS LOWER POPS BUT A QUIETER
PERIOD IN GENERAL. A STRONG UPPER LEVEL LOW WILL BE WORKING EASTWARD
THROUGH THE CENTRAL PLAINS ON TUESDAY. WHILE THE STRONGEST STORMS
APPEAR TO BE IN IOWA...SOME MAY SNEAK INTO OUR AREA AS WELL LATER IN
THE DAY...BUT MORE LIKELY IN THE EVENING. WEAK INSTABILITY WILL BE
PRESENT DURING THE DAY COUPLED WITH INCREASING SHEAR AND MAY SUPPORT
SCATTERED DEVELOPMENT AGAIN DURING THE AFTERNOON.
KMD
&&
.LONG TERM...
310 PM CDT
TUESDAY NIGHT THROUGH THURSDAY...
THE PERIOD WILL BEGIN FAIRLY ACTIVE AS A NOW CLOSED UPPER LEVEL
SYSTEM CONTINUES TO SLOWLY PROGRESS EAST THROUGH THE NORTHERN
PLAINS AND UPPER MIDWEST. GUIDANCE IN FAIR AGREEMENT WITH OVERALL
EVOLUTION/PLACEMENT OF THIS SYSTEM AS WELL SEVERAL IMPULSES
LIFTING NORTHEAST ACROSS THE CWA/REGION...WHILE SURFACE LOW AND
BOUNDARY REMAIN WELL TO THE NORTHWEST AND WEST DURING THIS TIME.
ALTHOUGH PLACEMENT OF STRONGER AND MORE WIDESPREAD THUNDERSTORM
DEVELOPMENT WILL INITIALLY BE SITUATED WEST OF THE
CWA...INCREASING MOISTURE AND INSTABILITY OUT AHEAD OF THIS SYSTEM
TUESDAY/TUESDAY NIGHT WHILE PERSISTENT FORCING IS PRESENT COULD
ALLOW FOR SCATTERED DEVELOPMENT ACROSS THE CWA. FOCUS WILL THEN
SHIFT TOWARDS MORE WIDESPREAD DEVELOPMENT APPROACHING OUT AHEAD OF
EASTWARD MOVING FRONTAL BOUNDARY OVER IOWA. THESE
THUNDERSTORMS...DEVELOPING THROUGHOUT THE DAY TUESDAY...WILL BE
APPROACHING THE CWA BY THE MID TO LATE EVENING TIME FRAME. WITH
PERSISTENT FORCING THROUGHOUT THE NIGHT...WOULD EXPECT SHOWERS AND
THUNDERSTORMS TO BE POSSIBLE OVER MUCH OF THE CWA. ALTHOUGH
CONFIDENCE IS HIGHER WITH COVERAGE...CONFIDENCE IS LOWER WITH
REGARD TO INTENSITY OF THESE STORMS. QUESTIONS AS TO HOW MUCH THE
ATMOSPHERE WILL DESTABILIZE ON TUESDAY WILL PLAY A FACTOR WITH
INTENSITY MAINTAINING ITSELF WEDNESDAY EVENING. DO THINK AT LEAST
A FEW/ISOLATED STRONGER STORMS WILL BE POSSIBLE...BUT WILL NEED TO
MONITOR FOR POSSIBLE HIGHER COVERAGE OF THESE STRONGER STORMS.
WHILE FRONTAL BOUNDARY WILL CONTINUE TO PUSH EAST WEDNESDAY
MORNING...THUNDERSTORM CHANCES WILL BE ENDING FROM WEST TO EAST
WITH THE ARRIVAL OF MUCH DRIER AIR ON BACKSIDE OF THIS SYSTEM.
HOWEVER...THERE IS SOME VARIABILITY WITH HOW QUICKLY THIS FRONT
PUSHES THROUGH. WITH THIS SYSTEM CLOSING ITSELF OFF...I AM A
LITTLE CONCERNED THAT A MORE PREFERRED SOLUTION WOULD BE FOR A
SLOWER TIME FRAME. IF THIS WERE TO OCCUR...THEN THERE WOULD BE AN
ADDITIONAL CHANCE FOR STRONG TO SEVERE THUNDERSTORMS ACROSS THE
EASTERN CWA WEDNESDAY AS MOISTURE/INSTABILITY WOULD CONTINUE TO
STREAM NORTHWARD OUT AHEAD OF IT. HOWEVER...WOULD THINK ALREADY
PRESENT CLOUD COVER AND PRECIP WOULD LIMIT HOW UNSTABLE THE CWA
WOULD BE...WITH BETTER INSTABILITY LIKELY STAYING EAST OF THE CWA.
THUNDERSTORM CHANCES WILL LIKELY DIMINISH FROM WEST TO EAST IN THE
AFTERNOON AND ALTHOUGH PRECIP CHANCES MAY LINGER IN THE
EVENING...THUNDER SHOULD STAY TO THE EAST. HIGH TEMPERATURES ON
WEDNESDAY WILL LIKELY OCCUR EARLY IN THE DAY WEDNESDAY AND WHILE
STRONGER WESTERLY WINDS INCREASE INTO THE AFTERNOON. DESPITE SOME
TIMING DIFFERENCE WITH THE EVOLUTION OF THIS LARGE SYSTEM...WITH
DRIER AIR WORKING IN AND BETTER FORCING EXITING...THURSDAY IS
APPEARING TO BE DRY.
RODRIGUEZ
THURSDAY NIGHT THROUGH MONDAY
THE MAIN POINT OF INTEREST FOR THE REST OF THIS WEEK AND INTO THE
WEEKEND IS AN UPPER LEVEL DISTURBANCE AND ASSOCIATED SFC LOW.
WATER VAPOR SATELLITE SHOWS A MID-LEVEL TROUGH DEVELOPING OVER THE
DAKOTAS THAT WILL PROGRESS EAST THROUGH THE UPPER GREAT LAKES
REGION THE NEXT COUPLE OF DAYS. BOTH NAM AND GFS GUIDANCE ARE IN
RATHER GOOD AGREEMENT WITH THE TIMING AND INTENSITY OF THIS
DISTURBANCE. THIS TAKES THE CENTER OF THE LOW NORTH OF THE CWA
THROUGH MN AND WI. POPS ARE PROBABLE WITH THIS SETUP WITH EMBEDDED
WAVES WITHIN THE TROUGH, HOWEVER THERE IS UNCERTAINTY AS TO THE
AMOUNT OF POPS THE AREA WILL SEE WITH THIS DISTURBANCE. SATURDAY
LOOKS TO BE THE FAVORABLE DAY FOR CONVECTION WITH AN ISOLATED
THUNDERSTORM. COVERAGE OF TSRA WILL LIKELY BE SMALL. EXPECT TEMPS
TO DROP WITH FROPA BUT RECOVER BACK INTO THE 80S WITH SWLY FLOW AT
THE SFC. DEWPOINTS LOOK TO STAY PUT IN THE LOWER TO MID 60S. THE
SFC LOW WILL LEAD TO DEVELOPMENT OF STRONG PRESSURE GRADIENT
FAVORING STRONG WIND GUSTS AS THIS DISTURBANCE PROGRESSES ACROSS
THE REGION.
KRULL
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* PERIODIC CHANCES FOR THUNDERSTORMS.
* CHANCE FOR FOG OR LOW CIGS TUESDAY MORNING.
BMD
//DISCUSSION...UPDATED 06Z...
SCATTERED SHOWERS AND THUNDERSTORMS ARE IN PLACE ACROSS NORTHERN
ILLINOIS LATE THIS EVENING AND WILL CONTINUE THOUGH SOME OF THE
OVERNIGHT HOURS...THOUGH DO EXPECT A GENERAL DIMINISHING TREND IN
THE INTENSITY AND COVERAGE AS FORCING BEGINS TO EXIT EAST AND
INSTABILITY CONTINUES TO WANE NOCTURNALLY. WILL HAVE TO MONITOR
THE THREAT FOR LOW CIGS OR FOG DEVELOPING OVERNIGHT...ESPECIALLY
IF THERE IS PARTIAL CLEARING WHICH WILL ALLOW RADIATIVE COOLING
GIVEN LIGHT WINDS.
DURING THE DAY TUESDAY...INSTABILITY QUICKLY BUILDS THROUGH THE
MORNING WITH FORECAST SOUNDINGS SHOWING UNCAPPED PARCELS BY LATE
MORNING AND EARLY AFTERNOON. WOULDNT BE SURPRISED TO SEE A FEW
POP UPS HOWEVER TRANSIENT UPPER LEVEL RIDGING SHOULD SUPPRESS ANY
MORE WIDESPREAD CONVECTION EARLY IN THE DAY. BY MID AFTERNOON
HOWEVER... MID LEVEL HEIGHT FALLS BEGIN TO OVERSPREAD THE REGION
AHEAD OF A POTENT SYSTEM LIFTING ACROSS THE PLAINS. THE FOCUS
TOMORROW AFTERNOON AND EVENING SHOULD BE ALONG AND WEST OF THE
MISSISSIPPI RIVER HOWEVER GIVEN THE INSTABILITY AND BROAD SCALE
ASCENT CANNOT RULE OUT ISOLATED ACTIVITY NEAR THE
TERMINALS...ESPECIALLY RFD. EXPECT THUNDERSTORMS TO MOVE INTO
NORTHERN ILLINOIS LATE EVENING INTO THE EARLY OVERNIGHT HOURS.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM CONFIDENCE IN WIND TRENDS.
* LOW-MEDIUM CONFIDENCE IN TSRA/SHRA TIMING.
* LOW CONFIDENCE IN CIG/VSBY TRENDS EARLY TUESDAY MORNING.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
* WEDNESDAY...CHANCE OF TSRA. STRONG/GUSTY SOUTHWEST WINDS.
* THURSDAY...DRY/VFR. STRONG/GUSTY WESTERLY WINDS.
* FRIDAY...DRY/VFR. SOUTH/SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. SOUTH/SOUTHEAST WINDS.
* SUNDAY...CHANCE OF TSRA. SOUTHWEST WINDS.
&&
.MARINE...
247 AM CDT
A QUASI STATIONARY FRONTAL BOUNDARY IS DRAPED ACROSS CENTRAL LAKE
MICHIGAN EARLY THIS MORNING BUT IS EXPECTED TO BEGIN LIFTING
NORTH TODAY AS AN UNSEASONABLY STRONG SYSTEM DEVELOPS OVER THE
CENTRAL PLAINS AND DEEPENS AS IT LIFTS ACROSS WISCONSIN LATE THIS
EVENING AND INTO ONTARIO ON WEDNESDAY. SOUTH WINDS RAMP UP ACROSS
THE LAKE TONIGHT INCREASING INTO THE 20 TO 30 KT RANGE AND
CONTINUE THROUGH THE DAY WEDNESDAY VEERING TO THE SOUTHWEST.
WEDNESDAY NIGHT THE COLD FRONT WILL SWEEP ACROSS THE LAKE WITH
WINDS TURNING WESTERLY AND STAYING PROPPED UP AROUND 30 KT. CANNOT
RULE OUT A WINDOW OF GALES AT THIS TIME. WINDS SHOULD TAPER SOME
THROUGH THE DAY THURSDAY. ANOTHER STRONG LOW IS POSSIBLE OVER THE
WEEKEND DRAGGING A COLD FRONT ACROSS LAKE MICHIGAN ON SUNDAY.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1246 AM CDT TUE AUG 18 2015
.UPDATE...847 PM CDT
THUNDERSTORMS CONTINUE TO FIRE THIS EVENING ALONG VARIOUS
BOUNDARIES. THE MAIN BOUNDARY EXTENDS FROM CENTRAL COOK COUNTY
THROUGH SOUTHERN DUPAGE INTO NORTHERN KENDALL. LATEST RAP
ANALYSIS INDICATES WE HAVE AROUND 500 J/KG OF CAPE TO WORK WITH
ALONG THE BOUNDARY SO ADDITIONAL ISOLATED TO SCATTERED STORMS ARE
POSSIBLE. THIS IS ESPECIALLY TRUE AS THE CURRENT STORMS PRODUCE
THEIR OWN BOUNDARIES. WITH LONG SKINNY CAPE VALUES IN FORECAST AND
00Z SOUNDINGS...EXPECTING ONLY THE STRONGEST STORMS TO PRODUCE
WIND GUSTS UP TO 50-60 MPH AND SMALL HAIL. ALL STORMS HOWEVER WILL
PRODUCE TORRENTIAL RAINFALL. THUS FAR MOST OF THE STORMS HAVE
EITHER BEEN MOVING OR WEAKENING JUST FAST ENOUGH TO AVOID FLOODING
ISSUES...BUT WILL CONTINUE TO MONITOR FOR TRAINING STORMS THAT
COULD PRODUCE FLASH FLOODING AND STANDING WATER.
STILL HAVE LOW CONFIDENCE IN EXACTLY HOW THE REST OF THE EVENING
WILL PROGRESS IN REGARDS TO STORMS. THE HRRR HAS DONE A VERY GOOD
JOB AT CAPTURING MOST OF WHAT HAS HAPPENED THUS FAR SO POP
FORECAST IS MOSTLY BASED OFF OF IT. EXPECTING MORE SCATTERED PULSE
CONVECTION ALONG THE OUTFLOW BOUNDARIES WHILE THE AREA OF
CONVECTION OVER WESTERN IL SPREADS EAST. THINKING THE STORMS OVER
WESTERN IL WILL WEAKEN AS THEY SHIFT EAST...BUT MORE STORMS WILL
PROBABLY FORM ALONG ANY OUTFLOW BOUNDARIES THE ORIGINAL STORMS
PRODUCE. IN ADDITION..A SHORTWAVE TROUGH IS OVER EASTERN IOWA SO
THINKING THAT WILL HELP FORCE WAVES OF CONVECTION THROUGH THE
NIGHT. HAD A VERY DIFFICULT TIME BEING MORE DETERMINISTIC IN MY
FORECAST SIMPLY BECAUSE OF THE MESOSCALE NATURE OF THE STORMS.
THEREFORE HAVE HIGH CONFIDENCE IN SCATTERED STORMS MAINLY
NORTHWEST OF A DE MOTTE THROUGH GIBSON CITY LINE...BUT LOW
CONFIDENCE IN EXACT TIMING AND COVERAGE AT ANY GIVEN TIME.
WITH THE AMPLE MOISTURE FROM THE STORMS...KEPT PATCHY FOG GOING
AFTER MIDNIGHT.
JEE
&&
.SHORT TERM...
340 PM CDT
THROUGH TUESDAY...
SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE THIS AFTERNOON. SEVERAL
OF THE STRONGER STORMS HAVE REPORTED WIND GUSTS AROUND 50 MPH AND
SMALL HAIL...ALONG WITH MODERATE TO HEAVY DOWNPOURS AND LIKELY
LOCALLY 1 INCH PLUS RAINFALL TOTALS.
THIS ACTIVITY IS COURTESY OF SEVERAL FEATURES...THE FIRST AN UPPER
LEVEL DISTURBANCE PUSHING INTO CENTRAL INDIANA WITH A WELL DEFINED
CLOSED CIRCULATION ON WATER VAPOR SATELLITE IMAGERY. THE SECOND IS A
COLD FRONT STRETCHED SOUTHWEST FROM NORTHERN LAKE MICHIGAN...THROUGH
CENTRAL WISCONSIN...THEN ORIENTED WEST-EAST IN MOST OF IOWA. SPC
MESOANALYSIS SHOWS MODERATE INSTABILITY WITH GOOD LOW LEVEL LAPSE
RATES...BUT POOR SHEAR...AND MODEST PW VALUES. THEREFORE LOCALLY
HEAVY RAINFALL AND GUSTY WINDS WILL REMAIN THE PREDOMINANT HAZARDS
THROUGH THE AFTERNOON AND EARLY EVENING HOURS. THESE STORMS ARE
PRODUCING OUTFLOW BOUNDARIES THAT WILL LOCALLY INCREASE
CONVERGENCE SUGGESTING SCATTERED STORMS REMAIN POSSIBLE AREA-WIDE.
WHILE THE CONVECTIVE EVOLUTION IS STILL A BIT UNCERTAIN...EXPECT A
DIURNAL DECREASE IN THE COVERAGE AWAY FROM THE COLD FRONT AS THE
UPPER LEVEL LOW ENTERS INDIANA EXITS TO THE EAST...ESPECIALLY INTO
EASTERN ILLINOIS AND NORTHWEST INDIANA. ADDITIONALLY...MODEL
GUIDANCE STALLS THE FRONT OUT ALONG A DUBUQUE TO ROCKFORD TO
MILWAUKEE LINE. THE NEXT SET OF DISTURBANCES PROPAGATE PARALLEL TO
THE COLD FRONTAL BOUNDARY...THUS HAVE RETAINED HIGHEST POPS IN NORTH
CENTRAL ILLINOIS AND ALONG THE WISCONSIN BORDER. A TRAILING
DISTURBANCE IN WESTERN IOWA WILL MOVE THROUGH THE AREA OVERNIGHT
WHICH MAY ALLOW SOME FURTHER EASTWARD PROGRESSION OVERNIGHT.
HEIGHT RISES AND SUBSIDENCE IN WAKE OF THE DEPARTING DISTURBANCE BUT
BROAD SW MOIST LOWER LEVEL FLOW SUPPORTS LOWER POPS BUT A QUIETER
PERIOD IN GENERAL. A STRONG UPPER LEVEL LOW WILL BE WORKING EASTWARD
THROUGH THE CENTRAL PLAINS ON TUESDAY. WHILE THE STRONGEST STORMS
APPEAR TO BE IN IOWA...SOME MAY SNEAK INTO OUR AREA AS WELL LATER IN
THE DAY...BUT MORE LIKELY IN THE EVENING. WEAK INSTABILITY WILL BE
PRESENT DURING THE DAY COUPLED WITH INCREASING SHEAR AND MAY SUPPORT
SCATTERED DEVELOPMENT AGAIN DURING THE AFTERNOON.
KMD
&&
.LONG TERM...
310 PM CDT
TUESDAY NIGHT THROUGH THURSDAY...
THE PERIOD WILL BEGIN FAIRLY ACTIVE AS A NOW CLOSED UPPER LEVEL
SYSTEM CONTINUES TO SLOWLY PROGRESS EAST THROUGH THE NORTHERN
PLAINS AND UPPER MIDWEST. GUIDANCE IN FAIR AGREEMENT WITH OVERALL
EVOLUTION/PLACEMENT OF THIS SYSTEM AS WELL SEVERAL IMPULSES
LIFTING NORTHEAST ACROSS THE CWA/REGION...WHILE SURFACE LOW AND
BOUNDARY REMAIN WELL TO THE NORTHWEST AND WEST DURING THIS TIME.
ALTHOUGH PLACEMENT OF STRONGER AND MORE WIDESPREAD THUNDERSTORM
DEVELOPMENT WILL INITIALLY BE SITUATED WEST OF THE
CWA...INCREASING MOISTURE AND INSTABILITY OUT AHEAD OF THIS SYSTEM
TUESDAY/TUESDAY NIGHT WHILE PERSISTENT FORCING IS PRESENT COULD
ALLOW FOR SCATTERED DEVELOPMENT ACROSS THE CWA. FOCUS WILL THEN
SHIFT TOWARDS MORE WIDESPREAD DEVELOPMENT APPROACHING OUT AHEAD OF
EASTWARD MOVING FRONTAL BOUNDARY OVER IOWA. THESE
THUNDERSTORMS...DEVELOPING THROUGHOUT THE DAY TUESDAY...WILL BE
APPROACHING THE CWA BY THE MID TO LATE EVENING TIME FRAME. WITH
PERSISTENT FORCING THROUGHOUT THE NIGHT...WOULD EXPECT SHOWERS AND
THUNDERSTORMS TO BE POSSIBLE OVER MUCH OF THE CWA. ALTHOUGH
CONFIDENCE IS HIGHER WITH COVERAGE...CONFIDENCE IS LOWER WITH
REGARD TO INTENSITY OF THESE STORMS. QUESTIONS AS TO HOW MUCH THE
ATMOSPHERE WILL DESTABILIZE ON TUESDAY WILL PLAY A FACTOR WITH
INTENSITY MAINTAINING ITSELF WEDNESDAY EVENING. DO THINK AT LEAST
A FEW/ISOLATED STRONGER STORMS WILL BE POSSIBLE...BUT WILL NEED TO
MONITOR FOR POSSIBLE HIGHER COVERAGE OF THESE STRONGER STORMS.
WHILE FRONTAL BOUNDARY WILL CONTINUE TO PUSH EAST WEDNESDAY
MORNING...THUNDERSTORM CHANCES WILL BE ENDING FROM WEST TO EAST
WITH THE ARRIVAL OF MUCH DRIER AIR ON BACKSIDE OF THIS SYSTEM.
HOWEVER...THERE IS SOME VARIABILITY WITH HOW QUICKLY THIS FRONT
PUSHES THROUGH. WITH THIS SYSTEM CLOSING ITSELF OFF...I AM A
LITTLE CONCERNED THAT A MORE PREFERRED SOLUTION WOULD BE FOR A
SLOWER TIME FRAME. IF THIS WERE TO OCCUR...THEN THERE WOULD BE AN
ADDITIONAL CHANCE FOR STRONG TO SEVERE THUNDERSTORMS ACROSS THE
EASTERN CWA WEDNESDAY AS MOISTURE/INSTABILITY WOULD CONTINUE TO
STREAM NORTHWARD OUT AHEAD OF IT. HOWEVER...WOULD THINK ALREADY
PRESENT CLOUD COVER AND PRECIP WOULD LIMIT HOW UNSTABLE THE CWA
WOULD BE...WITH BETTER INSTABILITY LIKELY STAYING EAST OF THE CWA.
THUNDERSTORM CHANCES WILL LIKELY DIMINISH FROM WEST TO EAST IN THE
AFTERNOON AND ALTHOUGH PRECIP CHANCES MAY LINGER IN THE
EVENING...THUNDER SHOULD STAY TO THE EAST. HIGH TEMPERATURES ON
WEDNESDAY WILL LIKELY OCCUR EARLY IN THE DAY WEDNESDAY AND WHILE
STRONGER WESTERLY WINDS INCREASE INTO THE AFTERNOON. DESPITE SOME
TIMING DIFFERENCE WITH THE EVOLUTION OF THIS LARGE SYSTEM...WITH
DRIER AIR WORKING IN AND BETTER FORCING EXITING...THURSDAY IS
APPEARING TO BE DRY.
RODRIGUEZ
THURSDAY NIGHT THROUGH MONDAY
THE MAIN POINT OF INTEREST FOR THE REST OF THIS WEEK AND INTO THE
WEEKEND IS AN UPPER LEVEL DISTURBANCE AND ASSOCIATED SFC LOW.
WATER VAPOR SATELLITE SHOWS A MID-LEVEL TROUGH DEVELOPING OVER THE
DAKOTAS THAT WILL PROGRESS EAST THROUGH THE UPPER GREAT LAKES
REGION THE NEXT COUPLE OF DAYS. BOTH NAM AND GFS GUIDANCE ARE IN
RATHER GOOD AGREEMENT WITH THE TIMING AND INTENSITY OF THIS
DISTURBANCE. THIS TAKES THE CENTER OF THE LOW NORTH OF THE CWA
THROUGH MN AND WI. POPS ARE PROBABLE WITH THIS SETUP WITH EMBEDDED
WAVES WITHIN THE TROUGH, HOWEVER THERE IS UNCERTAINTY AS TO THE
AMOUNT OF POPS THE AREA WILL SEE WITH THIS DISTURBANCE. SATURDAY
LOOKS TO BE THE FAVORABLE DAY FOR CONVECTION WITH AN ISOLATED
THUNDERSTORM. COVERAGE OF TSRA WILL LIKELY BE SMALL. EXPECT TEMPS
TO DROP WITH FROPA BUT RECOVER BACK INTO THE 80S WITH SWLY FLOW AT
THE SFC. DEWPOINTS LOOK TO STAY PUT IN THE LOWER TO MID 60S. THE
SFC LOW WILL LEAD TO DEVELOPMENT OF STRONG PRESSURE GRADIENT
FAVORING STRONG WIND GUSTS AS THIS DISTURBANCE PROGRESSES ACROSS
THE REGION.
KRULL
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* PERIODIC CHANCES FOR THUNDERSTORMS.
* CHANCE FOR FOG OR LOW CIGS TUESDAY MORNING.
BMD
//DISCUSSION...UPDATED 06Z...
SCATTERED SHOWERS AND THUNDERSTORMS ARE IN PLACE ACROSS NORTHERN
ILLINOIS LATE THIS EVENING AND WILL CONTINUE THOUGH SOME OF THE
OVERNIGHT HOURS...THOUGH DO EXPECT A GENERAL DIMINISHING TREND IN
THE INTENSITY AND COVERAGE AS FORCING BEGINS TO EXIT EAST AND
INSTABILITY CONTINUES TO WANE NOCTURNALLY. WILL HAVE TO MONITOR
THE THREAT FOR LOW CIGS OR FOG DEVELOPING OVERNIGHT...ESPECIALLY
IF THERE IS PARTIAL CLEARING WHICH WILL ALLOW RADIATIVE COOLING
GIVEN LIGHT WINDS.
DURING THE DAY TUESDAY...INSTABILITY QUICKLY BUILDS THROUGH THE
MORNING WITH FORECAST SOUNDINGS SHOWING UNCAPPED PARCELS BY LATE
MORNING AND EARLY AFTERNOON. WOULDNT BE SURPRISED TO SEE A FEW
POP UPS HOWEVER TRANSIENT UPPER LEVEL RIDGING SHOULD SUPPRESS ANY
MORE WIDESPREAD CONVECTION EARLY IN THE DAY. BY MID AFTERNOON
HOWEVER... MID LEVEL HEIGHT FALLS BEGIN TO OVERSPREAD THE REGION
AHEAD OF A POTENT SYSTEM LIFTING ACROSS THE PLAINS. THE FOCUS
TOMORROW AFTERNOON AND EVENING SHOULD BE ALONG AND WEST OF THE
MISSISSIPPI RIVER HOWEVER GIVEN THE INSTABILITY AND BROAD SCALE
ASCENT CANNOT RULE OUT ISOLATED ACTIVITY NEAR THE
TERMINALS...ESPECIALLY RFD. EXPECT THUNDERSTORMS TO MOVE INTO
NORTHERN ILLINOIS LATE EVENING INTO THE EARLY OVERNIGHT HOURS.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM CONFIDENCE IN WIND TRENDS.
* LOW-MEDIUM CONFIDENCE IN TSRA/SHRA TIMING.
* LOW CONFIDENCE IN CIG/VSBY TRENDS EARLY TUESDAY MORNING.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
* WEDNESDAY...CHANCE OF TSRA. STRONG/GUSTY SOUTHWEST WINDS.
* THURSDAY...DRY/VFR. STRONG/GUSTY WESTERLY WINDS.
* FRIDAY...DRY/VFR. SOUTH/SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. SOUTH/SOUTHEAST WINDS.
* SUNDAY...CHANCE OF TSRA. SOUTHWEST WINDS.
&&
.MARINE...
344 PM CDT
VARYING WINDS ACROSS THE LAKE THIS AFTERNOON ARE DUE TO LINGERING
BOUNDARY SITUATED OVER THE LAKE WHILE SURFACE LOW/TROUGH REMAINS
TO THE WEST. THESE VARYING WINDS WILL LIKELY PERSIST ON TUESDAY
AND INTO A PORTION OF TUESDAY NIGHT...BEFORE WINDS ACROSS THE
ENTIRE LAKE TURN MORE SOUTHERLY TUESDAY NIGHT INTO WEDNESDAY. THIS
WILL BE IN RESPONSE TO APPROACHING AND STRENGTHENING SURFACE LOW
OVER THE UPPER MIDWEST. EXPECT SPEEDS TO BE INCREASING TUESDAY
NIGHT BUT EXPECT SPEEDS TO REALLY RAMP UP ON WEDNESDAY AND
ESPECIALLY WEDNESDAY NIGHT AS THIS LOW FURTHER
STRENGTHENS/APPROACHES. HAVE MAINTAINED TO 30 KT WINDS ACROSS THE
LAKE...BUT AM A LITTLE CONCERNED THAT A PERIOD OF AT LEAST GALE
FORCE GUSTS WILL BE POSSIBLE...ESPECIALLY WEDNESDAY NIGHT. THESE
STRONGER WINDS WILL LIKELY BE PRESENT ACROSS THE NEARSHORE
WEDNESDAY INTO WEDNESDAY EVENING...BUT THESE HIGHER GUSTS MAY BE
POSSIBLE WELL INTO WEDNESDAY NIGHT. ALTHOUGH THESE STRONGER WINDS
MAY STILL BE OCCURRING THURSDAY MORNING...EXPECT SPEEDS TO BE
LOWERING INTO THE AFTERNOON.
RODRIGUEZ
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS DES MOINES IA
104 PM CDT TUE AUG 18 2015
.UPDATE...
ISSUED AT 100 PM CDT TUE AUG 18 2015
HAVE CANCELED THE FLASH FLOOD WATCH AS THE THREAT HAS ENDED. WILL
CONTINUE TO MONITOR THE SEVERE WEATHER THREAT THROUGH THE
AFTERNOON. DRY SLOT CONTINUES TO PROGRESS EAST INTO THE AREA AND
SHOULD BE THROUGH THE FORECAST AREA BY 4-5 PM. GREATEST
INSTABILITIES ARE SET UP TO THE EAST AND LIKELY WILL HAVE STRONGER
STORMS DEVELOP EAST OF THE AREA SOON. STILL CAN NOT DISCOUNT A
TRAILING LINE DEVELOPING BY MID AFTERNOON THAT WOULD PROGRESS
QUICKLY EAST ALONG THE LEADING EDGE OF THE DRY SLOT.
PREVIOUSLY UPDATED AT 1136 AM
EXPECT THE THREAT FOR HEAVY RAINFALL TO CONTINUE TO DIMINISH INTO
THIS AFTERNOON AS THE MID LEVEL DRY SLOT OVERSPREADS THE AREA.
PLAN IS TO DROP THE FLASH FLOOD WATCH SOMETIME EARLY AFTERNOON IF
TRENDS PERSIST. ANY STORM REDEVELOPMENT THIS AFTERNOON WILL HAVE
MUCH MORE PROGRESSIVE STORM MOTIONS THAT WILL LIMIT THE HEAVY RAIN
THREAT. GIVEN THE GOOD DYNAMICS ASSOCIATED WITH THIS UPPER SYSTEM
AND ATTENDANT SHEAR...THE SEVERE WEATHER THREAT SHOULD INCREASE
INTO THIS AFTERNOON AND CONTINUE THROUGH EARLY EVENING. SFC
INSTABILITY STILL IN QUESTION DUE TO LINGERING CLOUD COVER THROUGH
SYSTEM CLIMATOLOGY WOULD SUGGEST AN HOUR OF SUN WILL BE SUFFICIENT
AND THIS IS LIKELY IN SOME AREAS. A TORNADO THREAT WOULD INCREASE SHOULD
SFC INSTABILITY BECOME REALIZED.
.SHORT TERM /TODAY/...
ISSUED AT 411 AM CDT TUE AUG 18 2015
SHOULD BE A FAIRLY ACTIVE DAY TODAY AS AN UPPER TROUGH OVER THE
NORTHERN PLAINS DEEPENS AND DEVELOPS A CLOSED LOW AS IT MOVES INTO
MN WEDNESDAY MORNING. THERE APPEARS TO BE SEVERAL VORT MAXES OVER
THE PLAINS ASSOCIATED WITH THIS TROUGH WHICH WILL LIKELY SWEEP INTO
NORTHWEST AND NORTH CENTRAL IOWA TODAY. AT THE SURFACE...LOW
PRESSURE OVER NORTH CENTRAL KANSAS IS FORECAST TO LIFT NORTHEAST
INTO WESTERN THEN NORTHWEST IOWA BY LATE AFTERNOON BEFORE MOVING
INTO SOUTH CENTRAL MINNESOTA TONIGHT. A WARM FRONT WILL SHIFT
ACROSS CENTRAL IOWA LATER THIS MORNING INTO THE AFTERNOON BRINGING
THE FIRST ROUND OF PRECIPITATION TO CENTRAL IOWA. SHEAR THIS
MORNING IS NOT OVERLY IMPRESSIVE BUT WILL INCREASE AND DEEPEN WITH
TIME. CAPE VALUES INCREASE THIS MORNING THEN MODELS DIMINISH CAPE
THIS AFTERNOON BEFORE BRIEFLY INCREASING IT AGAIN LATE AFTERNOON
INTO THE EVENING ACROSS THE SOUTHWEST WITH THE PASSAGE OF A COLD
FRONT AS THE SURFACE LOW SHIFTS INTO MN. QC FORCING IS PARTICULARLY
IMPRESSIVE THIS MORNING ESPECIALLY OVER THE NORTH.
PWATS ACROSS THE NORTHWEST INTO NORTH CENTRAL APPROACH 2 INCHES AND
THIS IS OVER LOCATIONS THAT GOT QUITE A BIT OF RAINFALL IN THE
RECENT PAST. THE POTENTIAL FOR HEAVY RAINFALL COMBINED WITH ONE
HOUR FLASH FLOOD GUIDANCE OF 1.6 INCHES OR SO HAS PROMPTED THE
ISSUANCE OF A FLASH FLOOD WATCH ACROSS MUCH OF NORTHWEST INTO NORTH
CENTRAL IOWA FOR TODAY THOUGH I DO EXPECT THE HEAVIEST RAINFALL
FROM MID TO LATE MORNING INTO THE EARLY AFTERNOON.
FURTHER SOUTH WHERE THE BETTER INSTABILITY WILL RESIDE WILL BE A
CONDITIONAL POTENTIAL FOR SEVERE WEATHER FROM MID AFTERNOON INTO
EARLY EVENING WITH THE FRONTAL PASSAGE. THERE IS A FAIR AMOUNT OF
UNCERTAINTY AS TO WHAT THE EXTENT OF THE MORNING CONVECTION WILL BE
AND HOW MUCH WE WILL DESTABILIZE LATER TODAY AS MANY OF THE HI-RES
MODELS DRIBBLE CONVECTION ACROSS US FOR MUCH OF THE DAY BUT THEY DO
IN FACT ALL SUGGEST A SECOND ROUND OF CONVECTION IN THE MID
AFTERNOON THROUGH EARLY TO MID EVENING. AT PRESENT THE HRRR SEEMS
TO HAVE A DECENT HANDLE ON THE PRECIP THOUGH ITS A LITTLE TOO HEAVY
ON THE NORTHWARD EXTENT. THE WRF IS CAPTURING THE SOUTHERN PRECIP
AREA A LITTLE BETTER SO I TRIED TO GO WITH A BLEND OF THOSE TWO
MODELS. THE 00Z NAMDNG ALSO HAD A DECENT HANDLE ON PRECIP BUT THE
06Z RUN IS MISSING THE EXPANDING PRECIP ACROSS THE SOUTHWEST. I
HELD TEMPS DOWN A DEGREE OR TWO WITH ESPECIALLY SOUTH WITH THE
EXPECTED CLOUD COVER AND PRECIP. AS FOR POPS...I WENT FAIRLY HIGH
POPS FOR TODAY. IT SHOULD NOT BE RAINING ALL DAY BUT THERE WILL BE
A FEW ROUNDS OF PRECIP AND THE SCATTERED NATURE OF THE STORMS WILL
MAKE IT VERY DIFFICULT TO PIN DOWN TIME AND LOCATION.
.LONG TERM /TONIGHT THROUGH MONDAY/...
ISSUED AT 411 AM CDT TUE AUG 18 2015
FORECAST CHALLENGE EARLY ON IS WHERE OUR LOW WILL BE AT THE START OF
THE LONG TERM FCST PERIOD. MODELS SOMEWHAT SCATTERED WITH PLACEMENT
OF THE LOW AT 00Z WED. THE 00Z TUE EURO/GEM/UKMET ESSENTIALLY THE
MIDDLE PATH. THE 00Z TUE GFS IS NOW A FAST OUTLIER...AND THE 00Z
TUE NAM IS A SLIGHTLY SLOW OUTLIER THAN THE MIDDLE PATH MODELS.
AVAILABLE BAROCLINICITY AND RUN-TO-RUN INCREASINGLY ANOMALOUS
UPSTREAM 500MB SHORTWAVE AND -4 STD DEV SFC LOW SUGGEST THE
SLOWER...MORE ROBUST PATH MAY BE MORE REASONABLE TO FOLLOW. THUS
HAVE GONE WITH A BLEND OF THE NAM/EURO/GEM/UKMET. THIS BLEND
PLACES THE LOW IN NW IOWA AT 00Z WED. AT 00Z WED...THE BEST SLUG
OF FORCING WILL LIKELY BE EXITING OUR CWA AND THERE WILL BE THE
ATTENDANT COLD FRONT DROPPING DOWN ALONG OUR WESTERN COUNTIES INTO
MISSOURI.
SVR THREAT...0-6 KM MUCAPE VALUES MARGINAL AT 1000-1200 J/KG. 0-1 KM
HELICITY DECENT AS IT APPROACHES 200 M2/S2. LCL HEIGHTS ARE
SUFFICIENTLY LOW. GIVEN CLIMATOLOGY...STORM MODE MAY EVOLVE TO
LINEAR/BOWING OVERNIGHT. DCAPE VALUES EXCEED 1000 J/KG. NAM PICKING
UP ON PWATS UPWARDS OF 2 INCHES WITH THIS BOUNDARY PASSAGE...SO A
BRIEF HEAVY DOWNPOUR POSSIBLE. ADDITIONALLY...NAM PLACES RIGHT
ENTRANCE REGION OF 100KT JET STREAK IN TARGETED AREA.
HOWEVER...CONFIDENCE NOT THE GREATEST DUE TO LACK OF MODEL
CONSISTENCY AND THE FACT RAIN/CLOUDS THROUGHOUT THE DAY WILL
HINDER DESTABILIZATION. IF STORMS DO GO WITH THE COLD
FRONT...TORNADOES/DAMAGING WINDS LIKELY THE PRIMARY THREATS.
BY 09-12Z WED...BOUNDARY SHOULD BE WELL EAST OF DMX CWA. STRONG
W/NW CAA WILL BE IMMEDIATELY USHERED INTO IOWA AS 850MB TEMPS
SHOULD BE NEAR 8C ON OUR WESTERN CWA EDGE AND 11C ON OUR EASTERN
EDGE. WEDNESDAY AFTERNOON...LOW PROGGD TO DEEPEN TO MID 990MB
RANGE OVER NW WI...WHICH IS VERY ATYPICAL FOR THIS TIME OF YEAR.
GEFS ENSEMBLES SHOW THIS IS NEARING -4 TO -5 STD DEV. PRESSURE
GRADIENT NOT AS TIGHT IN IA AS IT WILL BE IN MN/WESTERN WI.
NONETHELESS...AROUND 3MB/100 KM...DEPENDING ON MODEL PREFERENCE.
FCST SOUNDINGS STILL SHOW AROUND 40 KTS TO THE TOP OF THE MIXED
LAYER. SO AM EXPECTING SFC WINDS IN THE 15 TO 25 MPH RANGE WITH
GUSTS NEARING 35 MPH...ESPECIALLY IN OUR NORTH. PAST SEVERAL MODEL
RUNS HAVE BEEN SUGGESTING ST/SC DECK WITH THE DEFORMATION ZONE
LINGERING ACROSS NORTHERN IA. THUS HAVE KEPT SLIGHT POPS WITH
MINIMAL QPF GOING THROUGH WED EVE. AT THE VERY LEAST...MAX TEMPS
WILL BE HELD DOWN DUE TO THE CLOUD COVER. WENT LOW 60S NORTH...BUT
THIS MAY NEED TO BE KNOCKED DOWN A FEW DEGREES IF ST DECK HOLDS.
THURSDAY INTO SATURDAY...SFC HIGH PRESSURE WILL PASS FROM THE OZARKS
INTO THE OHIO VALLEY REGION. THIS HIGH WILL BE STRONG ENOUGH TO KEEP
DMX CWA DRY THU AND FRI. TEMPS HAVE CERTAINLY TRENDING UPWARDS FOR
FRIDAY AND SATURDAY. THUS HAVE GONE A FEW DEGREES ABOVE GUIDANCE TO
ADD VALUE TO TEMPERATURE FCST.
SINCE LAST FRI...MODELS HAVE BEEN PLACING IA IN RETURN FLOW BY THE
WEEKEND. 00Z TUE LONG RANGE MODELS CONTINUE THIS...KEEPING THE GULF
WIDE OPEN WITH A 35 KT LLJ PRIMED TO TRANSPORT GULF MOISTURE INTO
IOWA. THIS SETUP WILL INCREASE TEMPS BACK INTO THE 80S AND BRING A
RETURN OF POPS FOR THE WEEKEND.
SUNDAY INTO EARLY NEXT WEEK...MODELS IN SURPRISINGLY GREAT
AGREEMENT...PLUS SHOWING RUN-TO-RUN CONSISTENCY GOOD WITH BRINGING A
STRONG SFC HIGH TOWARDS IOWA. AS CONFIDENCE/CONSISTENCY
INCREASING...TEMPS HAVE BEEN TRENDING DOWNWARD WITH CAA EXPECTED
AHEAD OF THIS HIGH. MAY NEED TO LOWER TEMPERATURES EVEN FURTHER IF
THIS SETUP HOLDS.
&&
.AVIATION...18/18Z
ISSUED AT 1251 PM CDT TUE AUG 18 2015
SCATTERED SHOWERS AND THUNDERSTORMS WILL MOVE THROUGH THIS
AFTERNOON AND WILL HAVE ATTENDANT CIG LOWERINGS TO MVFR TO
POSSIBLY LIFR AT TIMES. A PERIOD OF VFR IS POSSIBLE MOST LOCATIONS
FOLLOWING BEFORE IFR CIGS MOVE INTO NORTHERN IOWA OVERNIGHT. ALL
AREAS MAY LOWER TO MVFR TO IFR OVERNIGHT THEN CIGS GRADUALLY RISE
ON WEDNESDAY. WINDS BECOME SOUTHWEST TO WEST LATE AFTERNOON AND
EVENING THEN BECOMING GUSTY LATE.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...FAB
LONG TERM...KOTENBERG
AVIATION...DONAVON
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1251 PM CDT TUE AUG 18 2015
.UPDATE...
ISSUED AT 1136 AM CDT TUE AUG 18 2015
EXPECT THE THREAT FOR HEAVY RAINFALL TO CONTINUE TO DIMINISH INTO
THIS AFTERNOON AS THE MID LEVEL DRY SLOT OVERSPREADS THE AREA.
PLAN IS TO DROP THE FLASH FLOOD WATCH SOMETIME EARLY AFTERNOON IF
TRENDS PERSIST. ANY STORM REDEVELOPMENT THIS AFTERNOON WILL HAVE
MUCH MORE PROGRESSIVE STORM MOTIONS THAT WILL LIMIT THE HEAVY RAIN
THREAT. GIVEN THE GOOD DYNAMICS ASSOCIATED WITH THIS UPPER SYSTEM
AND ATTENDANT SHEAR...THE SEVERE WEATHER THREAT SHOULD INCREASE
INTO THIS AFTERNOON AND CONTINUE THROUGH EARLY EVENING. SFC
INSTABILITY STILL IN QUESTION DUE TO LINGERING CLOUD COVER THROUGH
SYSTEM CLIMATOLOGY WOULD SUGGEST AN HOUR OF SUN WILL BE SUFFICIENT
AND THIS IS LIKELY IN SOME AREAS. A TORNADO THREAT WOULD INCREASE SHOULD
SFC INSTABILITY BECOME REALIZED.
&&
.SHORT TERM /TODAY/...
ISSUED AT 411 AM CDT TUE AUG 18 2015
SHOULD BE A FAIRLY ACTIVE DAY TODAY AS AN UPPER TROUGH OVER THE
NORTHERN PLAINS DEEPENS AND DEVELOPS A CLOSED LOW AS IT MOVES INTO
MN WEDNESDAY MORNING. THERE APPEARS TO BE SEVERAL VORT MAXES OVER
THE PLAINS ASSOCIATED WITH THIS TROUGH WHICH WILL LIKELY SWEEP INTO
NORTHWEST AND NORTH CENTRAL IOWA TODAY. AT THE SURFACE...LOW
PRESSURE OVER NORTH CENTRAL KANSAS IS FORECAST TO LIFT NORTHEAST
INTO WESTERN THEN NORTHWEST IOWA BY LATE AFTERNOON BEFORE MOVING
INTO SOUTH CENTRAL MINNESOTA TONIGHT. A WARM FRONT WILL SHIFT
ACROSS CENTRAL IOWA LATER THIS MORNING INTO THE AFTERNOON BRINGING
THE FIRST ROUND OF PRECIPITATION TO CENTRAL IOWA. SHEAR THIS
MORNING IS NOT OVERLY IMPRESSIVE BUT WILL INCREASE AND DEEPEN WITH
TIME. CAPE VALUES INCREASE THIS MORNING THEN MODELS DIMINISH CAPE
THIS AFTERNOON BEFORE BRIEFLY INCREASING IT AGAIN LATE AFTERNOON
INTO THE EVENING ACROSS THE SOUTHWEST WITH THE PASSAGE OF A COLD
FRONT AS THE SURFACE LOW SHIFTS INTO MN. QC FORCING IS PARTICULARLY
IMPRESSIVE THIS MORNING ESPECIALLY OVER THE NORTH.
PWATS ACROSS THE NORTHWEST INTO NORTH CENTRAL APPROACH 2 INCHES AND
THIS IS OVER LOCATIONS THAT GOT QUITE A BIT OF RAINFALL IN THE
RECENT PAST. THE POTENTIAL FOR HEAVY RAINFALL COMBINED WITH ONE
HOUR FLASH FLOOD GUIDANCE OF 1.6 INCHES OR SO HAS PROMPTED THE
ISSUANCE OF A FLASH FLOOD WATCH ACROSS MUCH OF NORTHWEST INTO NORTH
CENTRAL IOWA FOR TODAY THOUGH I DO EXPECT THE HEAVIEST RAINFALL
FROM MID TO LATE MORNING INTO THE EARLY AFTERNOON.
FURTHER SOUTH WHERE THE BETTER INSTABILITY WILL RESIDE WILL BE A
CONDITIONAL POTENTIAL FOR SEVERE WEATHER FROM MID AFTERNOON INTO
EARLY EVENING WITH THE FRONTAL PASSAGE. THERE IS A FAIR AMOUNT OF
UNCERTAINTY AS TO WHAT THE EXTENT OF THE MORNING CONVECTION WILL BE
AND HOW MUCH WE WILL DESTABILIZE LATER TODAY AS MANY OF THE HI-RES
MODELS DRIBBLE CONVECTION ACROSS US FOR MUCH OF THE DAY BUT THEY DO
IN FACT ALL SUGGEST A SECOND ROUND OF CONVECTION IN THE MID
AFTERNOON THROUGH EARLY TO MID EVENING. AT PRESENT THE HRRR SEEMS
TO HAVE A DECENT HANDLE ON THE PRECIP THOUGH ITS A LITTLE TOO HEAVY
ON THE NORTHWARD EXTENT. THE WRF IS CAPTURING THE SOUTHERN PRECIP
AREA A LITTLE BETTER SO I TRIED TO GO WITH A BLEND OF THOSE TWO
MODELS. THE 00Z NAMDNG ALSO HAD A DECENT HANDLE ON PRECIP BUT THE
06Z RUN IS MISSING THE EXPANDING PRECIP ACROSS THE SOUTHWEST. I
HELD TEMPS DOWN A DEGREE OR TWO WITH ESPECIALLY SOUTH WITH THE
EXPECTED CLOUD COVER AND PRECIP. AS FOR POPS...I WENT FAIRLY HIGH
POPS FOR TODAY. IT SHOULD NOT BE RAINING ALL DAY BUT THERE WILL BE
A FEW ROUNDS OF PRECIP AND THE SCATTERED NATURE OF THE STORMS WILL
MAKE IT VERY DIFFICULT TO PIN DOWN TIME AND LOCATION.
.LONG TERM /TONIGHT THROUGH MONDAY/...
ISSUED AT 411 AM CDT TUE AUG 18 2015
FORECAST CHALLENGE EARLY ON IS WHERE OUR LOW WILL BE AT THE START OF
THE LONG TERM FCST PERIOD. MODELS SOMEWHAT SCATTERED WITH PLACEMENT
OF THE LOW AT 00Z WED. THE 00Z TUE EURO/GEM/UKMET ESSENTIALLY THE
MIDDLE PATH. THE 00Z TUE GFS IS NOW A FAST OUTLIER...AND THE 00Z
TUE NAM IS A SLIGHTLY SLOW OUTLIER THAN THE MIDDLE PATH MODELS.
AVAILABLE BAROCLINICITY AND RUN-TO-RUN INCREASINGLY ANOMALOUS
UPSTREAM 500MB SHORTWAVE AND -4 STD DEV SFC LOW SUGGEST THE
SLOWER...MORE ROBUST PATH MAY BE MORE REASONABLE TO FOLLOW. THUS
HAVE GONE WITH A BLEND OF THE NAM/EURO/GEM/UKMET. THIS BLEND
PLACES THE LOW IN NW IOWA AT 00Z WED. AT 00Z WED...THE BEST SLUG
OF FORCING WILL LIKELY BE EXITING OUR CWA AND THERE WILL BE THE
ATTENDANT COLD FRONT DROPPING DOWN ALONG OUR WESTERN COUNTIES INTO
MISSOURI.
SVR THREAT...0-6 KM MUCAPE VALUES MARGINAL AT 1000-1200 J/KG. 0-1 KM
HELICITY DECENT AS IT APPROACHES 200 M2/S2. LCL HEIGHTS ARE
SUFFICIENTLY LOW. GIVEN CLIMATOLOGY...STORM MODE MAY EVOLVE TO
LINEAR/BOWING OVERNIGHT. DCAPE VALUES EXCEED 1000 J/KG. NAM PICKING
UP ON PWATS UPWARDS OF 2 INCHES WITH THIS BOUNDARY PASSAGE...SO A
BRIEF HEAVY DOWNPOUR POSSIBLE. ADDITIONALLY...NAM PLACES RIGHT
ENTRANCE REGION OF 100KT JET STREAK IN TARGETED AREA.
HOWEVER...CONFIDENCE NOT THE GREATEST DUE TO LACK OF MODEL
CONSISTENCY AND THE FACT RAIN/CLOUDS THROUGHOUT THE DAY WILL
HINDER DESTABILIZATION. IF STORMS DO GO WITH THE COLD
FRONT...TORNADOES/DAMAGING WINDS LIKELY THE PRIMARY THREATS.
BY 09-12Z WED...BOUNDARY SHOULD BE WELL EAST OF DMX CWA. STRONG
W/NW CAA WILL BE IMMEDIATELY USHERED INTO IOWA AS 850MB TEMPS
SHOULD BE NEAR 8C ON OUR WESTERN CWA EDGE AND 11C ON OUR EASTERN
EDGE. WEDNESDAY AFTERNOON...LOW PROGGD TO DEEPEN TO MID 990MB
RANGE OVER NW WI...WHICH IS VERY ATYPICAL FOR THIS TIME OF YEAR.
GEFS ENSEMBLES SHOW THIS IS NEARING -4 TO -5 STD DEV. PRESSURE
GRADIENT NOT AS TIGHT IN IA AS IT WILL BE IN MN/WESTERN WI.
NONETHELESS...AROUND 3MB/100 KM...DEPENDING ON MODEL PREFERENCE.
FCST SOUNDINGS STILL SHOW AROUND 40 KTS TO THE TOP OF THE MIXED
LAYER. SO AM EXPECTING SFC WINDS IN THE 15 TO 25 MPH RANGE WITH
GUSTS NEARING 35 MPH...ESPECIALLY IN OUR NORTH. PAST SEVERAL MODEL
RUNS HAVE BEEN SUGGESTING ST/SC DECK WITH THE DEFORMATION ZONE
LINGERING ACROSS NORTHERN IA. THUS HAVE KEPT SLIGHT POPS WITH
MINIMAL QPF GOING THROUGH WED EVE. AT THE VERY LEAST...MAX TEMPS
WILL BE HELD DOWN DUE TO THE CLOUD COVER. WENT LOW 60S NORTH...BUT
THIS MAY NEED TO BE KNOCKED DOWN A FEW DEGREES IF ST DECK HOLDS.
THURSDAY INTO SATURDAY...SFC HIGH PRESSURE WILL PASS FROM THE OZARKS
INTO THE OHIO VALLEY REGION. THIS HIGH WILL BE STRONG ENOUGH TO KEEP
DMX CWA DRY THU AND FRI. TEMPS HAVE CERTAINLY TRENDING UPWARDS FOR
FRIDAY AND SATURDAY. THUS HAVE GONE A FEW DEGREES ABOVE GUIDANCE TO
ADD VALUE TO TEMPERATURE FCST.
SINCE LAST FRI...MODELS HAVE BEEN PLACING IA IN RETURN FLOW BY THE
WEEKEND. 00Z TUE LONG RANGE MODELS CONTINUE THIS...KEEPING THE GULF
WIDE OPEN WITH A 35 KT LLJ PRIMED TO TRANSPORT GULF MOISTURE INTO
IOWA. THIS SETUP WILL INCREASE TEMPS BACK INTO THE 80S AND BRING A
RETURN OF POPS FOR THE WEEKEND.
SUNDAY INTO EARLY NEXT WEEK...MODELS IN SURPRISINGLY GREAT
AGREEMENT...PLUS SHOWING RUN-TO-RUN CONSISTENCY GOOD WITH BRINGING A
STRONG SFC HIGH TOWARDS IOWA. AS CONFIDENCE/CONSISTENCY
INCREASING...TEMPS HAVE BEEN TRENDING DOWNWARD WITH CAA EXPECTED
AHEAD OF THIS HIGH. MAY NEED TO LOWER TEMPERATURES EVEN FURTHER IF
THIS SETUP HOLDS.
&&
.AVIATION...18/18Z
ISSUED AT 1251 PM CDT TUE AUG 18 2015
SCATTERED SHOWERS AND THUNDERSTORMS WILL MOVE THROUGH THIS
AFTERNOON AND WILL HAVE ATTENDANT CIG LOWERINGS TO MVFR TO
POSSIBLY LIFR AT TIMES. A PERIOD OF VFR IS POSSIBLE MOST LOCATIONS
FOLLOWING BEFORE IFR CIGS MOVE INTO NORTHERN IOWA OVERNIGHT. ALL
AREAS MAY LOWER TO MVFR TO IFR OVERNIGHT THEN CIGS GRADUALLY RISE
ON WEDNESDAY. WINDS BECOME SOUTHWEST TO WEST LATE AFTERNOON AND
EVENING THEN BECOMING GUSTY LATE.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 7 PM CDT THIS EVENING FOR CALHOUN-
CARROLL-CRAWFORD-EMMET-HANCOCK-HUMBOLDT-KOSSUTH-PALO ALTO-
POCAHONTAS-SAC-WEBSTER-WINNEBAGO-WRIGHT.
&&
$$
UPDATE...DONAVON
SHORT TERM...FAB
LONG TERM...KOTENBERG
AVIATION...DONAVON
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1136 AM CDT TUE AUG 18 2015
.UPDATE...
ISSUED AT 1136 AM CDT TUE AUG 18 2015
EXPECT THE THREAT FOR HEAVY RAINFALL TO CONTINUE TO DIMINISH INTO
THIS AFTERNOON AS THE MID LEVEL DRY SLOT OVERSPREADS THE AREA.
PLAN IS TO DROP THE FLASH FLOOD WATCH SOMETIME EARLY AFTERNOON IF
TRENDS PERSIST. ANY STORM REDEVELOPMENT THIS AFTERNOON WILL HAVE
MUCH MORE PROGRESSIVE STORM MOTIONS THAT WILL LIMIT THE HEAVY RAIN
THREAT. GIVEN THE GOOD DYNAMICS ASSOCIATED WITH THIS UPPER SYSTEM
AND ATTENDANT SHEAR...THE SEVERE WEATHER THREAT SHOULD INCREASE
INTO THIS AFTERNOON AND CONTINUE THROUGH EARLY EVENING. SFC
INSTABILITY STILL IN QUESTION DUE TO LINGERING CLOUD COVER THROUGH
SYSTEM CLIMATOLOGY WOULD SUGGEST AN HOUR OF SUN WILL BE SUFFICIENT
AND THIS IS LIKELY IN SOME AREAS. A TORNADO THREAT WOULD INCREASE SHOULD
SFC INSTABILITY BECOME REALIZED.
&&
.SHORT TERM /TODAY/...
ISSUED AT 411 AM CDT TUE AUG 18 2015
SHOULD BE A FAIRLY ACTIVE DAY TODAY AS AN UPPER TROUGH OVER THE
NORTHERN PLAINS DEEPENS AND DEVELOPS A CLOSED LOW AS IT MOVES INTO
MN WEDNESDAY MORNING. THERE APPEARS TO BE SEVERAL VORT MAXES OVER
THE PLAINS ASSOCIATED WITH THIS TROUGH WHICH WILL LIKELY SWEEP INTO
NORTHWEST AND NORTH CENTRAL IOWA TODAY. AT THE SURFACE...LOW
PRESSURE OVER NORTH CENTRAL KANSAS IS FORECAST TO LIFT NORTHEAST
INTO WESTERN THEN NORTHWEST IOWA BY LATE AFTERNOON BEFORE MOVING
INTO SOUTH CENTRAL MINNESOTA TONIGHT. A WARM FRONT WILL SHIFT
ACROSS CENTRAL IOWA LATER THIS MORNING INTO THE AFTERNOON BRINGING
THE FIRST ROUND OF PRECIPITATION TO CENTRAL IOWA. SHEAR THIS
MORNING IS NOT OVERLY IMPRESSIVE BUT WILL INCREASE AND DEEPEN WITH
TIME. CAPE VALUES INCREASE THIS MORNING THEN MODELS DIMINISH CAPE
THIS AFTERNOON BEFORE BRIEFLY INCREASING IT AGAIN LATE AFTERNOON
INTO THE EVENING ACROSS THE SOUTHWEST WITH THE PASSAGE OF A COLD
FRONT AS THE SURFACE LOW SHIFTS INTO MN. QC FORCING IS PARTICULARLY
IMPRESSIVE THIS MORNING ESPECIALLY OVER THE NORTH.
PWATS ACROSS THE NORTHWEST INTO NORTH CENTRAL APPROACH 2 INCHES AND
THIS IS OVER LOCATIONS THAT GOT QUITE A BIT OF RAINFALL IN THE
RECENT PAST. THE POTENTIAL FOR HEAVY RAINFALL COMBINED WITH ONE
HOUR FLASH FLOOD GUIDANCE OF 1.6 INCHES OR SO HAS PROMPTED THE
ISSUANCE OF A FLASH FLOOD WATCH ACROSS MUCH OF NORTHWEST INTO NORTH
CENTRAL IOWA FOR TODAY THOUGH I DO EXPECT THE HEAVIEST RAINFALL
FROM MID TO LATE MORNING INTO THE EARLY AFTERNOON.
FURTHER SOUTH WHERE THE BETTER INSTABILITY WILL RESIDE WILL BE A
CONDITIONAL POTENTIAL FOR SEVERE WEATHER FROM MID AFTERNOON INTO
EARLY EVENING WITH THE FRONTAL PASSAGE. THERE IS A FAIR AMOUNT OF
UNCERTAINTY AS TO WHAT THE EXTENT OF THE MORNING CONVECTION WILL BE
AND HOW MUCH WE WILL DESTABILIZE LATER TODAY AS MANY OF THE HI-RES
MODELS DRIBBLE CONVECTION ACROSS US FOR MUCH OF THE DAY BUT THEY DO
IN FACT ALL SUGGEST A SECOND ROUND OF CONVECTION IN THE MID
AFTERNOON THROUGH EARLY TO MID EVENING. AT PRESENT THE HRRR SEEMS
TO HAVE A DECENT HANDLE ON THE PRECIP THOUGH ITS A LITTLE TOO HEAVY
ON THE NORTHWARD EXTENT. THE WRF IS CAPTURING THE SOUTHERN PRECIP
AREA A LITTLE BETTER SO I TRIED TO GO WITH A BLEND OF THOSE TWO
MODELS. THE 00Z NAMDNG ALSO HAD A DECENT HANDLE ON PRECIP BUT THE
06Z RUN IS MISSING THE EXPANDING PRECIP ACROSS THE SOUTHWEST. I
HELD TEMPS DOWN A DEGREE OR TWO WITH ESPECIALLY SOUTH WITH THE
EXPECTED CLOUD COVER AND PRECIP. AS FOR POPS...I WENT FAIRLY HIGH
POPS FOR TODAY. IT SHOULD NOT BE RAINING ALL DAY BUT THERE WILL BE
A FEW ROUNDS OF PRECIP AND THE SCATTERED NATURE OF THE STORMS WILL
MAKE IT VERY DIFFICULT TO PIN DOWN TIME AND LOCATION.
.LONG TERM /TONIGHT THROUGH MONDAY/...
ISSUED AT 411 AM CDT TUE AUG 18 2015
FORECAST CHALLENGE EARLY ON IS WHERE OUR LOW WILL BE AT THE START OF
THE LONG TERM FCST PERIOD. MODELS SOMEWHAT SCATTERED WITH PLACEMENT
OF THE LOW AT 00Z WED. THE 00Z TUE EURO/GEM/UKMET ESSENTIALLY THE
MIDDLE PATH. THE 00Z TUE GFS IS NOW A FAST OUTLIER...AND THE 00Z
TUE NAM IS A SLIGHTLY SLOW OUTLIER THAN THE MIDDLE PATH MODELS.
AVAILABLE BAROCLINICITY AND RUN-TO-RUN INCREASINGLY ANOMALOUS
UPSTREAM 500MB SHORTWAVE AND -4 STD DEV SFC LOW SUGGEST THE
SLOWER...MORE ROBUST PATH MAY BE MORE REASONABLE TO FOLLOW. THUS
HAVE GONE WITH A BLEND OF THE NAM/EURO/GEM/UKMET. THIS BLEND
PLACES THE LOW IN NW IOWA AT 00Z WED. AT 00Z WED...THE BEST SLUG
OF FORCING WILL LIKELY BE EXITING OUR CWA AND THERE WILL BE THE
ATTENDANT COLD FRONT DROPPING DOWN ALONG OUR WESTERN COUNTIES INTO
MISSOURI.
SVR THREAT...0-6 KM MUCAPE VALUES MARGINAL AT 1000-1200 J/KG. 0-1 KM
HELICITY DECENT AS IT APPROACHES 200 M2/S2. LCL HEIGHTS ARE
SUFFICIENTLY LOW. GIVEN CLIMATOLOGY...STORM MODE MAY EVOLVE TO
LINEAR/BOWING OVERNIGHT. DCAPE VALUES EXCEED 1000 J/KG. NAM PICKING
UP ON PWATS UPWARDS OF 2 INCHES WITH THIS BOUNDARY PASSAGE...SO A
BRIEF HEAVY DOWNPOUR POSSIBLE. ADDITIONALLY...NAM PLACES RIGHT
ENTRANCE REGION OF 100KT JET STREAK IN TARGETED AREA.
HOWEVER...CONFIDENCE NOT THE GREATEST DUE TO LACK OF MODEL
CONSISTENCY AND THE FACT RAIN/CLOUDS THROUGHOUT THE DAY WILL
HINDER DESTABILIZATION. IF STORMS DO GO WITH THE COLD
FRONT...TORNADOES/DAMAGING WINDS LIKELY THE PRIMARY THREATS.
BY 09-12Z WED...BOUNDARY SHOULD BE WELL EAST OF DMX CWA. STRONG
W/NW CAA WILL BE IMMEDIATELY USHERED INTO IOWA AS 850MB TEMPS
SHOULD BE NEAR 8C ON OUR WESTERN CWA EDGE AND 11C ON OUR EASTERN
EDGE. WEDNESDAY AFTERNOON...LOW PROGGD TO DEEPEN TO MID 990MB
RANGE OVER NW WI...WHICH IS VERY ATYPICAL FOR THIS TIME OF YEAR.
GEFS ENSEMBLES SHOW THIS IS NEARING -4 TO -5 STD DEV. PRESSURE
GRADIENT NOT AS TIGHT IN IA AS IT WILL BE IN MN/WESTERN WI.
NONETHELESS...AROUND 3MB/100 KM...DEPENDING ON MODEL PREFERENCE.
FCST SOUNDINGS STILL SHOW AROUND 40 KTS TO THE TOP OF THE MIXED
LAYER. SO AM EXPECTING SFC WINDS IN THE 15 TO 25 MPH RANGE WITH
GUSTS NEARING 35 MPH...ESPECIALLY IN OUR NORTH. PAST SEVERAL MODEL
RUNS HAVE BEEN SUGGESTING ST/SC DECK WITH THE DEFORMATION ZONE
LINGERING ACROSS NORTHERN IA. THUS HAVE KEPT SLIGHT POPS WITH
MINIMAL QPF GOING THROUGH WED EVE. AT THE VERY LEAST...MAX TEMPS
WILL BE HELD DOWN DUE TO THE CLOUD COVER. WENT LOW 60S NORTH...BUT
THIS MAY NEED TO BE KNOCKED DOWN A FEW DEGREES IF ST DECK HOLDS.
THURSDAY INTO SATURDAY...SFC HIGH PRESSURE WILL PASS FROM THE OZARKS
INTO THE OHIO VALLEY REGION. THIS HIGH WILL BE STRONG ENOUGH TO KEEP
DMX CWA DRY THU AND FRI. TEMPS HAVE CERTAINLY TRENDING UPWARDS FOR
FRIDAY AND SATURDAY. THUS HAVE GONE A FEW DEGREES ABOVE GUIDANCE TO
ADD VALUE TO TEMPERATURE FCST.
SINCE LAST FRI...MODELS HAVE BEEN PLACING IA IN RETURN FLOW BY THE
WEEKEND. 00Z TUE LONG RANGE MODELS CONTINUE THIS...KEEPING THE GULF
WIDE OPEN WITH A 35 KT LLJ PRIMED TO TRANSPORT GULF MOISTURE INTO
IOWA. THIS SETUP WILL INCREASE TEMPS BACK INTO THE 80S AND BRING A
RETURN OF POPS FOR THE WEEKEND.
SUNDAY INTO EARLY NEXT WEEK...MODELS IN SURPRISINGLY GREAT
AGREEMENT...PLUS SHOWING RUN-TO-RUN CONSISTENCY GOOD WITH BRINGING A
STRONG SFC HIGH TOWARDS IOWA. AS CONFIDENCE/CONSISTENCY
INCREASING...TEMPS HAVE BEEN TRENDING DOWNWARD WITH CAA EXPECTED
AHEAD OF THIS HIGH. MAY NEED TO LOWER TEMPERATURES EVEN FURTHER IF
THIS SETUP HOLDS.
&&
.AVIATION...18/12Z
ISSUED AT 700 AM CDT MON AUG 17 2015
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO EXPAND ACROSS THE WEST
HALF OF CENTRAL IOWA. LOCALLY HEAVY RAINFALL AND LOW CIGS/VSBYS
WILL BE THE MAIN THREAT THIS MORNING. MID TO LATE AFTN THROUGH MID
EVENING AS A SURFACE LOW SHIFTS INTO MN ADDITIONAL STORMS WILL
DEVELOP ALONG A COLD FRONT. IFR CONDITIONS WILL PERSIST THROUGH 06Z
BEFORE IMPROVING AS THE FRONT PUSHES OUT OF THE TAF LOCATIONS.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 7 PM CDT THIS EVENING FOR CALHOUN-
CARROLL-CRAWFORD-EMMET-HANCOCK-HUMBOLDT-KOSSUTH-PALO ALTO-
POCAHONTAS-SAC-WEBSTER-WINNEBAGO-WRIGHT.
&&
$$
UPDATE...DONAVON
SHORT TERM...FAB
LONG TERM...KOTENBERG
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
700 AM CDT TUE AUG 18 2015
.SHORT TERM /TODAY/...
ISSUED AT 411 AM CDT TUE AUG 18 2015
SHOULD BE A FAIRLY ACTIVE DAY TODAY AS AN UPPER TROUGH OVER THE
NORTHERN PLAINS DEEPENS AND DEVELOPS A CLOSED LOW AS IT MOVES INTO
MN WEDNESDAY MORNING. THERE APPEARS TO BE SEVERAL VORT MAXES OVER
THE PLAINS ASSOCIATED WITH THIS TROUGH WHICH WILL LIKELY SWEEP INTO
NORTHWEST AND NORTH CENTRAL IOWA TODAY. AT THE SURFACE...LOW
PRESSURE OVER NORTH CENTRAL KANSAS IS FORECAST TO LIFT NORTHEAST
INTO WESTERN THEN NORTHWEST IOWA BY LATE AFTERNOON BEFORE MOVING
INTO SOUTH CENTRAL MINNESOTA TONIGHT. A WARM FRONT WILL SHIFT
ACROSS CENTRAL IOWA LATER THIS MORNING INTO THE AFTERNOON BRINGING
THE FIRST ROUND OF PRECIPITATION TO CENTRAL IOWA. SHEAR THIS
MORNING IS NOT OVERLY IMPRESSIVE BUT WILL INCREASE AND DEEPEN WITH
TIME. CAPE VALUES INCREASE THIS MORNING THEN MODELS DIMINISH CAPE
THIS AFTERNOON BEFORE BRIEFLY INCREASING IT AGAIN LATE AFTERNOON
INTO THE EVENING ACROSS THE SOUTHWEST WITH THE PASSAGE OF A COLD
FRONT AS THE SURFACE LOW SHIFTS INTO MN. QC FORCING IS PARTICULARLY
IMPRESSIVE THIS MORNING ESPECIALLY OVER THE NORTH.
PWATS ACROSS THE NORTHWEST INTO NORTH CENTRAL APPROACH 2 INCHES AND
THIS IS OVER LOCATIONS THAT GOT QUITE A BIT OF RAINFALL IN THE
RECENT PAST. THE POTENTIAL FOR HEAVY RAINFALL COMBINED WITH ONE
HOUR FLASH FLOOD GUIDANCE OF 1.6 INCHES OR SO HAS PROMPTED THE
ISSUANCE OF A FLASH FLOOD WATCH ACROSS MUCH OF NORTHWEST INTO NORTH
CENTRAL IOWA FOR TODAY THOUGH I DO EXPECT THE HEAVIEST RAINFALL
FROM MID TO LATE MORNING INTO THE EARLY AFTERNOON.
FURTHER SOUTH WHERE THE BETTER INSTABILITY WILL RESIDE WILL BE A
CONDITIONAL POTENTIAL FOR SEVERE WEATHER FROM MID AFTERNOON INTO
EARLY EVENING WITH THE FRONTAL PASSAGE. THERE IS A FAIR AMOUNT OF
UNCERTAINTY AS TO WHAT THE EXTENT OF THE MORNING CONVECTION WILL BE
AND HOW MUCH WE WILL DESTABILIZE LATER TODAY AS MANY OF THE HI-RES
MODELS DRIBBLE CONVECTION ACROSS US FOR MUCH OF THE DAY BUT THEY DO
IN FACT ALL SUGGEST A SECOND ROUND OF CONVECTION IN THE MID
AFTERNOON THROUGH EARLY TO MID EVENING. AT PRESENT THE HRRR SEEMS
TO HAVE A DECENT HANDLE ON THE PRECIP THOUGH ITS A LITTLE TOO HEAVY
ON THE NORTHWARD EXTENT. THE WRF IS CAPTURING THE SOUTHERN PRECIP
AREA A LITTLE BETTER SO I TRIED TO GO WITH A BLEND OF THOSE TWO
MODELS. THE 00Z NAMDNG ALSO HAD A DECENT HANDLE ON PRECIP BUT THE
06Z RUN IS MISSING THE EXPANDING PRECIP ACROSS THE SOUTHWEST. I
HELD TEMPS DOWN A DEGREE OR TWO WITH ESPECIALLY SOUTH WITH THE
EXPECTED CLOUD COVER AND PRECIP. AS FOR POPS...I WENT FAIRLY HIGH
POPS FOR TODAY. IT SHOULD NOT BE RAINING ALL DAY BUT THERE WILL BE
A FEW ROUNDS OF PRECIP AND THE SCATTERED NATURE OF THE STORMS WILL
MAKE IT VERY DIFFICULT TO PIN DOWN TIME AND LOCATION.
.LONG TERM /TONIGHT THROUGH MONDAY/...
ISSUED AT 411 AM CDT TUE AUG 18 2015
FORECAST CHALLENGE EARLY ON IS WHERE OUR LOW WILL BE AT THE START OF
THE LONG TERM FCST PERIOD. MODELS SOMEWHAT SCATTERED WITH PLACEMENT
OF THE LOW AT 00Z WED. THE 00Z TUE EURO/GEM/UKMET ESSENTIALLY THE
MIDDLE PATH. THE 00Z TUE GFS IS NOW A FAST OUTLIER...AND THE 00Z
TUE NAM IS A SLIGHTLY SLOW OUTLIER THAN THE MIDDLE PATH MODELS.
AVAILABLE BAROCLINICITY AND RUN-TO-RUN INCREASINGLY ANOMALOUS
UPSTREAM 500MB SHORTWAVE AND -4 STD DEV SFC LOW SUGGEST THE
SLOWER...MORE ROBUST PATH MAY BE MORE REASONABLE TO FOLLOW. THUS
HAVE GONE WITH A BLEND OF THE NAM/EURO/GEM/UKMET. THIS BLEND
PLACES THE LOW IN NW IOWA AT 00Z WED. AT 00Z WED...THE BEST SLUG
OF FORCING WILL LIKELY BE EXITING OUR CWA AND THERE WILL BE THE
ATTENDANT COLD FRONT DROPPING DOWN ALONG OUR WESTERN COUNTIES INTO
MISSOURI.
SVR THREAT...0-6 KM MUCAPE VALUES MARGINAL AT 1000-1200 J/KG. 0-1 KM
HELICITY DECENT AS IT APPROACHES 200 M2/S2. LCL HEIGHTS ARE
SUFFICIENTLY LOW. GIVEN CLIMATOLOGY...STORM MODE MAY EVOLVE TO
LINEAR/BOWING OVERNIGHT. DCAPE VALUES EXCEED 1000 J/KG. NAM PICKING
UP ON PWATS UPWARDS OF 2 INCHES WITH THIS BOUNDARY PASSAGE...SO A
BRIEF HEAVY DOWNPOUR POSSIBLE. ADDITIONALLY...NAM PLACES RIGHT
ENTRANCE REGION OF 100KT JET STREAK IN TARGETED AREA.
HOWEVER...CONFIDENCE NOT THE GREATEST DUE TO LACK OF MODEL
CONSISTENCY AND THE FACT RAIN/CLOUDS THROUGHOUT THE DAY WILL
HINDER DESTABILIZATION. IF STORMS DO GO WITH THE COLD
FRONT...TORNADOES/DAMAGING WINDS LIKELY THE PRIMARY THREATS.
BY 09-12Z WED...BOUNDARY SHOULD BE WELL EAST OF DMX CWA. STRONG
W/NW CAA WILL BE IMMEDIATELY USHERED INTO IOWA AS 850MB TEMPS
SHOULD BE NEAR 8C ON OUR WESTERN CWA EDGE AND 11C ON OUR EASTERN
EDGE. WEDNESDAY AFTERNOON...LOW PROGGD TO DEEPEN TO MID 990MB
RANGE OVER NW WI...WHICH IS VERY ATYPICAL FOR THIS TIME OF YEAR.
GEFS ENSEMBLES SHOW THIS IS NEARING -4 TO -5 STD DEV. PRESSURE
GRADIENT NOT AS TIGHT IN IA AS IT WILL BE IN MN/WESTERN WI.
NONETHELESS...AROUND 3MB/100 KM...DEPENDING ON MODEL PREFERENCE.
FCST SOUNDINGS STILL SHOW AROUND 40 KTS TO THE TOP OF THE MIXED
LAYER. SO AM EXPECTING SFC WINDS IN THE 15 TO 25 MPH RANGE WITH
GUSTS NEARING 35 MPH...ESPECIALLY IN OUR NORTH. PAST SEVERAL MODEL
RUNS HAVE BEEN SUGGESTING ST/SC DECK WITH THE DEFORMATION ZONE
LINGERING ACROSS NORTHERN IA. THUS HAVE KEPT SLIGHT POPS WITH
MINIMAL QPF GOING THROUGH WED EVE. AT THE VERY LEAST...MAX TEMPS
WILL BE HELD DOWN DUE TO THE CLOUD COVER. WENT LOW 60S NORTH...BUT
THIS MAY NEED TO BE KNOCKED DOWN A FEW DEGREES IF ST DECK HOLDS.
THURSDAY INTO SATURDAY...SFC HIGH PRESSURE WILL PASS FROM THE OZARKS
INTO THE OHIO VALLEY REGION. THIS HIGH WILL BE STRONG ENOUGH TO KEEP
DMX CWA DRY THU AND FRI. TEMPS HAVE CERTAINLY TRENDING UPWARDS FOR
FRIDAY AND SATURDAY. THUS HAVE GONE A FEW DEGREES ABOVE GUIDANCE TO
ADD VALUE TO TEMPERATURE FCST.
SINCE LAST FRI...MODELS HAVE BEEN PLACING IA IN RETURN FLOW BY THE
WEEKEND. 00Z TUE LONG RANGE MODELS CONTINUE THIS...KEEPING THE GULF
WIDE OPEN WITH A 35 KT LLJ PRIMED TO TRANSPORT GULF MOISTURE INTO
IOWA. THIS SETUP WILL INCREASE TEMPS BACK INTO THE 80S AND BRING A
RETURN OF POPS FOR THE WEEKEND.
SUNDAY INTO EARLY NEXT WEEK...MODELS IN SURPRISINGLY GREAT
AGREEMENT...PLUS SHOWING RUN-TO-RUN CONSISTENCY GOOD WITH BRINGING A
STRONG SFC HIGH TOWARDS IOWA. AS CONFIDENCE/CONSISTENCY
INCREASING...TEMPS HAVE BEEN TRENDING DOWNWARD WITH CAA EXPECTED
AHEAD OF THIS HIGH. MAY NEED TO LOWER TEMPERATURES EVEN FURTHER IF
THIS SETUP HOLDS.
&&
.AVIATION...18/12Z
ISSUED AT 700 AM CDT MON AUG 17 2015
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO EXPAND ACROSS THE WEST
HALF OF CENTRAL IOWA. LOCALLY HEAVY RAINFALL AND LOW CIGS/VSBYS
WILL BE THE MAIN THREAT THIS MORNING. MID TO LATE AFTN THROUGH MID
EVENING AS A SURFACE LOW SHIFTS INTO MN ADDITIONAL STORMS WILL
DEVELOP ALONG A COLD FRONT. IFR CONDITIONS WILL PERSIST THROUGH 06Z
BEFORE IMPROVING AS THE FRONT PUSHES OUT OF THE TAF LOCATIONS.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH THIS EVENING FOR CALHOUN-CARROLL-
CRAWFORD-EMMET-HANCOCK-HUMBOLDT-KOSSUTH-PALO ALTO-POCAHONTAS-SAC-
WEBSTER-WINNEBAGO-WRIGHT.
&&
$$
SHORT TERM...FAB
LONG TERM...KOTENBERG
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
417 AM CDT TUE AUG 18 2015
.SHORT TERM /TODAY/...
ISSUED AT 411 AM CDT TUE AUG 18 2015
SHOULD BE A FAIRLY ACTIVE DAY TODAY AS AN UPPER TROUGH OVER THE
NORTHERN PLAINS DEEPENS AND DEVELOPS A CLOSED LOW AS IT MOVES INTO
MN WEDNESDAY MORNING. THERE APPEARS TO BE SEVERAL VORT MAXES OVER
THE PLAINS ASSOCIATED WITH THIS TROUGH WHICH WILL LIKELY SWEEP INTO
NORTHWEST AND NORTH CENTRAL IOWA TODAY. AT THE SURFACE...LOW
PRESSURE OVER NORTH CENTRAL KANSAS IS FORECAST TO LIFT NORTHEAST
INTO WESTERN THEN NORTHWEST IOWA BY LATE AFTERNOON BEFORE MOVING
INTO SOUTH CENTRAL MINNESOTA TONIGHT. A WARM FRONT WILL SHIFT
ACROSS CENTRAL IOWA LATER THIS MORNING INTO THE AFTERNOON BRINGING
THE FIRST ROUND OF PRECIPITATION TO CENTRAL IOWA. SHEAR THIS
MORNING IS NOT OVERLY IMPRESSIVE BUT WILL INCREASE AND DEEPEN WITH
TIME. CAPE VALUES INCREASE THIS MORNING THEN MODELS DIMINISH CAPE
THIS AFTERNOON BEFORE BRIEFLY INCREASING IT AGAIN LATE AFTERNOON
INTO THE EVENING ACROSS THE SOUTHWEST WITH THE PASSAGE OF A COLD
FRONT AS THE SURFACE LOW SHIFTS INTO MN. QC FORCING IS PARTICULARLY
IMPRESSIVE THIS MORNING ESPECIALLY OVER THE NORTH.
PWATS ACROSS THE NORTHWEST INTO NORTH CENTRAL APPROACH 2 INCHES AND
THIS IS OVER LOCATIONS THAT GOT QUITE A BIT OF RAINFALL IN THE
RECENT PAST. THE POTENTIAL FOR HEAVY RAINFALL COMBINED WITH ONE
HOUR FLASH FLOOD GUIDANCE OF 1.6 INCHES OR SO HAS PROMPTED THE
ISSUANCE OF A FLASH FLOOD WATCH ACROSS MUCH OF NORTHWEST INTO NORTH
CENTRAL IOWA FOR TODAY THOUGH I DO EXPECT THE HEAVIEST RAINFALL
FROM MID TO LATE MORNING INTO THE EARLY AFTERNOON.
FURTHER SOUTH WHERE THE BETTER INSTABILITY WILL RESIDE WILL BE A
CONDITIONAL POTENTIAL FOR SEVERE WEATHER FROM MID AFTERNOON INTO
EARLY EVENING WITH THE FRONTAL PASSAGE. THERE IS A FAIR AMOUNT OF
UNCERTAINTY AS TO WHAT THE EXTENT OF THE MORNING CONVECTION WILL BE
AND HOW MUCH WE WILL DESTABILIZE LATER TODAY AS MANY OF THE HI-RES
MODELS DRIBBLE CONVECTION ACROSS US FOR MUCH OF THE DAY BUT THEY DO
IN FACT ALL SUGGEST A SECOND ROUND OF CONVECTION IN THE MID
AFTERNOON THROUGH EARLY TO MID EVENING. AT PRESENT THE HRRR SEEMS
TO HAVE A DECENT HANDLE ON THE PRECIP THOUGH ITS A LITTLE TOO HEAVY
ON THE NORTHWARD EXTENT. THE WRF IS CAPTURING THE SOUTHERN PRECIP
AREA A LITTLE BETTER SO I TRIED TO GO WITH A BLEND OF THOSE TWO
MODELS. THE 00Z NAMDNG ALSO HAD A DECENT HANDLE ON PRECIP BUT THE
06Z RUN IS MISSING THE EXPANDING PRECIP ACROSS THE SOUTHWEST. I
HELD TEMPS DOWN A DEGREE OR TWO WITH ESPECIALLY SOUTH WITH THE
EXPECTED CLOUD COVER AND PRECIP. AS FOR POPS...I WENT FAIRLY HIGH
POPS FOR TODAY. IT SHOULD NOT BE RAINING ALL DAY BUT THERE WILL BE
A FEW ROUNDS OF PRECIP AND THE SCATTERED NATURE OF THE STORMS WILL
MAKE IT VERY DIFFICULT TO PIN DOWN TIME AND LOCATION.
.LONG TERM /TONIGHT THROUGH MONDAY/...
ISSUED AT 411 AM CDT TUE AUG 18 2015
FORECAST CHALLENGE EARLY ON IS WHERE OUR LOW WILL BE AT THE START OF
THE LONG TERM FCST PERIOD. MODELS SOMEWHAT SCATTERED WITH PLACEMENT
OF THE LOW AT 00Z WED. THE 00Z TUE EURO/GEM/UKMET ESSENTIALLY THE
MIDDLE PATH. THE 00Z TUE GFS IS NOW A FAST OUTLIER...AND THE 00Z
TUE NAM IS A SLIGHTLY SLOW OUTLIER THAN THE MIDDLE PATH MODELS.
AVAILABLE BAROCLINICITY AND RUN-TO-RUN INCREASINGLY ANOMALOUS
UPSTREAM 500MB SHORTWAVE AND -4 STD DEV SFC LOW SUGGEST THE
SLOWER...MORE ROBUST PATH MAY BE MORE REASONABLE TO FOLLOW. THUS
HAVE GONE WITH A BLEND OF THE NAM/EURO/GEM/UKMET. THIS BLEND
PLACES THE LOW IN NW IOWA AT 00Z WED. AT 00Z WED...THE BEST SLUG
OF FORCING WILL LIKELY BE EXITING OUR CWA AND THERE WILL BE THE
ATTENDANT COLD FRONT DROPPING DOWN ALONG OUR WESTERN COUNTIES INTO
MISSOURI.
SVR THREAT...0-6 KM MUCAPE VALUES MARGINAL AT 1000-1200 J/KG. 0-1 KM
HELICITY DECENT AS IT APPROACHES 200 M2/S2. LCL HEIGHTS ARE
SUFFICIENTLY LOW. GIVEN CLIMATOLOGY...STORM MODE MAY EVOLVE TO
LINEAR/BOWING OVERNIGHT. DCAPE VALUES EXCEED 1000 J/KG. NAM PICKING
UP ON PWATS UPWARDS OF 2 INCHES WITH THIS BOUNDARY PASSAGE...SO A
BRIEF HEAVY DOWNPOUR POSSIBLE. ADDITIONALLY...NAM PLACES RIGHT
ENTRANCE REGION OF 100KT JET STREAK IN TARGETED AREA.
HOWEVER...CONFIDENCE NOT THE GREATEST DUE TO LACK OF MODEL
CONSISTENCY AND THE FACT RAIN/CLOUDS THROUGHOUT THE DAY WILL
HINDER DESTABILIZATION. IF STORMS DO GO WITH THE COLD
FRONT...TORNADOES/DAMAGING WINDS LIKELY THE PRIMARY THREATS.
BY 09-12Z WED...BOUNDARY SHOULD BE WELL EAST OF DMX CWA. STRONG
W/NW CAA WILL BE IMMEDIATELY USHERED INTO IOWA AS 850MB TEMPS
SHOULD BE NEAR 8C ON OUR WESTERN CWA EDGE AND 11C ON OUR EASTERN
EDGE. WEDNESDAY AFTERNOON...LOW PROGGD TO DEEPEN TO MID 990MB
RANGE OVER NW WI...WHICH IS VERY ATYPICAL FOR THIS TIME OF YEAR.
GEFS ENSEMBLES SHOW THIS IS NEARING -4 TO -5 STD DEV. PRESSURE
GRADIENT NOT AS TIGHT IN IA AS IT WILL BE IN MN/WESTERN WI.
NONETHELESS...AROUND 3MB/100 KM...DEPENDING ON MODEL PREFERENCE.
FCST SOUNDINGS STILL SHOW AROUND 40 KTS TO THE TOP OF THE MIXED
LAYER. SO AM EXPECTING SFC WINDS IN THE 15 TO 25 MPH RANGE WITH
GUSTS NEARING 35 MPH...ESPECIALLY IN OUR NORTH. PAST SEVERAL MODEL
RUNS HAVE BEEN SUGGESTING ST/SC DECK WITH THE DEFORMATION ZONE
LINGERING ACROSS NORTHERN IA. THUS HAVE KEPT SLIGHT POPS WITH
MINIMAL QPF GOING THROUGH WED EVE. AT THE VERY LEAST...MAX TEMPS
WILL BE HELD DOWN DUE TO THE CLOUD COVER. WENT LOW 60S NORTH...BUT
THIS MAY NEED TO BE KNOCKED DOWN A FEW DEGREES IF ST DECK HOLDS.
THURSDAY INTO SATURDAY...SFC HIGH PRESSURE WILL PASS FROM THE OZARKS
INTO THE OHIO VALLEY REGION. THIS HIGH WILL BE STRONG ENOUGH TO KEEP
DMX CWA DRY THU AND FRI. TEMPS HAVE CERTAINLY TRENDING UPWARDS FOR
FRIDAY AND SATURDAY. THUS HAVE GONE A FEW DEGREES ABOVE GUIDANCE TO
ADD VALUE TO TEMPERATURE FCST.
SINCE LAST FRI...MODELS HAVE BEEN PLACING IA IN RETURN FLOW BY THE
WEEKEND. 00Z TUE LONG RANGE MODELS CONTINUE THIS...KEEPING THE GULF
WIDE OPEN WITH A 35 KT LLJ PRIMED TO TRANSPORT GULF MOISTURE INTO
IOWA. THIS SETUP WILL INCREASE TEMPS BACK INTO THE 80S AND BRING A
RETURN OF POPS FOR THE WEEKEND.
SUNDAY INTO EARLY NEXT WEEK...MODELS IN SURPRISINGLY GREAT
AGREEMENT...PLUS SHOWING RUN-TO-RUN CONSISTENCY GOOD WITH BRINGING A
STRONG SFC HIGH TOWARDS IOWA. AS CONFIDENCE/CONSISTENCY
INCREASING...TEMPS HAVE BEEN TRENDING DOWNWARD WITH CAA EXPECTED
AHEAD OF THIS HIGH. MAY NEED TO LOWER TEMPERATURES EVEN FURTHER IF
THIS SETUP HOLDS.
&&
.AVIATION...18/06Z
ISSUED AT 1147 PM CDT MON AUG 17 2015
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP OVER WEST-
CENTRAL IOWA DURING THE OVERNIGHT HOURS AND SPREAD EAST-NORTHEAST
LIKELY AFFECTING FOD/MCW/DSM PRIOR TO NEXT TAF UPDATE. CIGS WILL
CONTINUE TO BOUNCE FROM IFR TO MVFR TO VFR DEPENDING ON IF SITE
RECEIVES RAIN...BUT HIGHER CONFIDENCE IN EXTENDED TIME FRAME OF
MVFR CIGS/VIS AND KEPT MENTION AS RAIN LOOKS TO SPREAD OVER MUCH
OF CENTRAL IOWA TOWARDS 12Z-14Z TUESDAY. THE MORE WIDESPREAD AND
HEAVIER RAIN BY MIDDAY INTO THE AFTERNOON WILL BRING THE BEST
POTENTIAL FOR IFR VIS AND CIGS. WINDS INCREASE AND SHIFT WEST-
NORTHWEST TUESDAY EVENING BEHIND THE COLD FRONT.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH THIS EVENING FOR CALHOUN-CARROLL-
CRAWFORD-EMMET-HANCOCK-HUMBOLDT-KOSSUTH-PALO ALTO-POCAHONTAS-SAC-
WEBSTER-WINNEBAGO-WRIGHT.
&&
$$
SHORT TERM...FAB
LONG TERM...KOTENBERG
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS TOPEKA KS
335 PM CDT TUE AUG 18 2015
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 335 PM CDT TUE AUG 18 2015
19Z WATER VAPOR SHOWS A CLOSED UPPER LOW OVER SD WHILE SURFACE OBS
PLACE THE LOW OVER NORTHWEST IA/SOUTHWEST MN BORDER. A STRONG COLD
FRONT EXTENDED SOUTH FROM THE SURFACE LOW THROUGH SOUTHEAST NEB TO
JUST WEST OF SLN. VISIBLE SATELLITE HAS SHOWN SOME BREAKS IN THE
CLOUDS AHEAD OF THE FRONT WHICH HAS ALLOWED TEMPS TO WARM INTO THE
LOWER 80S. THIS WOULD SUPPORT SURFACE BASED CAPE VALUES AROUND
1000J/KG WHILE 0-6 KM SHEAR INCREASES TO AROUND 45 KTS. SO THE
POTENTIAL FOR SEVERE STORMS REMAINS IN PLACE. MODELS SHOW AREA ALONG
AND SOUTH OF I-70 AS THE PLACES THAT SHOULD SEE THE BETTER
INSTABILITY. THEREFORE THINK THIS MAY BE WHERE STRONG TO SEVERE
STORMS DEVELOP THIS AFTERNOON, IF THEY STRENGTHEN. SINCE SURFACE
WINDS HAVE VEERED TO THE SOUTHWEST AHEAD OF THE FRONT, THE POTENTIAL
FOR TORNADOES APPEARS TO REMAIN FAIRLY SMALL. THE RAP AND HRRR,
WHICH HAVE SHOWN A BETTER TIMING FOR THE FRONT, TAKE THE BOUNDARY
EAST OF THE FORECAST AREA BETWEEN 8 AND 9 PM. THE RISK FOR SEVERE
WEATHER SHOULD DIMINISH QUICKLY BEHIND THE FRONT AS COOLER MORE
STABLE AIR COMES IN.
ONCE THE FRONT PASSES EAST, THINK THE REST OF TONIGHT WILL BE FAIRLY
UNEVENTFUL. THERE HAVE BEEN SOME LOWER CLOUDS ACROSS WESTERN NEB
MIST OF THE DAY BUT THE MODELS TEND TO KEEP THE LOWER CLOUDS TO THE
NORTH OVERNIGHT. THEREFORE WITH COLD AIR ADVECTION AND MOST LIKELY
PARTLY CLOUDY SKIES, LOWS IN THE MID AND UPPER 50S LOOKS ON TARGET.
BY LATE TONIGHT AND THROUGH THE MORNING WEDNESDAY, MODELS SWING A
DECENT VORT MAX THROUGH THE BASE OF THE UPPER TROUGH PASSING THROUGH
EASTERN KS. THERE IS NO SIGN OF LOW LEVEL MOISTURE ADVECTION OVER
THE COLD FRONT, BUT THERE IS AN INDICATION OF A SATURATED AIRMASS
ACROSS EAST CENTRAL KS WITH GOOD FRONTOGENESIS AS THE WAVE PASSES
OVERHEAD. BECAUSE OF THIS HAVE CONTINUED WITH SOME CHANCE POPS FOR
RAIN MAINLY OVER EAST CENTRAL KS. THERE SHOULD BE MORE DRY AIR OVER
NORTH CENTRAL AND NORTHEAST KS THAT WILL LIMIT PRECIP CHANCES. THE
COLD AIR ADVECTION WEAKENS THROUGH THE DAY WEDNESDAY, BUT THERE MAY
BE SOME CLOUDS LINGER. THEREFORE HIGHS ARE FORECAST TO TOP OUT IN
THE LOWER AND MID 70S. THIS IS ABOUT 15 DEGREES BELOW NORMAL FOR
THIS TIME OF YEAR.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 335 PM CDT TUE AUG 18 2015
LOWER LEVEL WINDS BACK TO THE WEST WEDNESDAY NIGHT AND THEN
SOUTHWEST INTO THURSDAY NIGHT BRINGING SOME WARMING BACK AND SURFACE
TEMPS SHOULD MODIFY CONSIDERABLY. HAVE KEPT VALUES NEAR TO BELOW
MOS FOR WEDNESDAY NIGHT IN LIGHT WINDS AND CLEAR SKIES. MODELS
TRENDING A BIT COOLER FOR FRIDAY WITH CONTINUED BACKED TO NEAR
SOUTHEAST WITH HIGHS STILL LIKELY CLOSE TO THOSE OF THURSDAY. PRECIP
CHANCES CONTINUE TO LOOK QUITE LOW THROUGH THURSDAY NIGHT. AT LEAST
SOME MOISTURE RETURNS AHEAD OF A WEAK UPPER WAVE FRIDAY...THOUGH
THERE REMAINS TO BE A WIDE DEGREE OF VARIANCE IN BOTH OF THESE
ELEMENTS...WITH A TREND TOWARD LOWER AVAILABLE MOISTURE NOTED. AT
THIS POINT CHANCES FOR ANYTHING MORE THAN ISOLATED PRECIP LOOK LOW.
FOR THE BEGINNING OF THE WEEKEND, RETURN FLOW WILL BE IN PLACE OVER
THE SOUTHERN AND CENTRAL PLAINS AHEAD OF A DEEPENING TROUGH OVER THE
NORTHERN ROCKIES. THIS SYSTEM WILL CONTINUE EASTWARD PROGRESSION
INTO THE DAY SATURDAY AND OVERNIGHT INTO SUNDAY BEFORE IT BECOMES
MORE NEGATIVELY TILTED AND LIFTS THROUGH THE UPPER MISSISSIPPI
VALLEY INTO THE GREAT LAKES REGION BY MONDAY. THIS LARGER SCALE
FEATURE SHOULD BRING ABOUT THE CHANCE OF ELEVATED STORMS FOR
SATURDAY MORNING AS A LLJ SHOULD HELP ENHANCE AN AREA OF ISENTROPIC
LIFT OVER EASTERN KS. INTO THE DAY, SOUNDINGS DO SUGGEST THAT STORM
POTENTIAL MAY BE LIMITED WITH A PRETTY STRONG CAP DEVELOPING OVER
THE REGION. THE BETTER CHANCE FOR THUNDERSTORM REDEVELOPMENT WILL
BE IN THE LATE AFTERNOON INTO THE EARLY EVENING AS SHEAR PROFILES
BECOME A LITTLE MORE ORGANIZED AND WAA INCREASES LOW LEVEL MOISTURE
ALONG WITH INSTABILITY OVER THE REGION. SOME POTENTIAL FOR STRONG
TO SEVERE STORMS COULD EXIST, BUT STILL TOO FAR OUT TO PINPOINT
OVERALL LIKELIHOOD. MODELS SEEM TO BE IN FAIRLY GOOD AGREEMENT FOR
THE MOST PART WITH EASTWARD PROGRESSION OF THE TROUGH. THE GFS
SOLUTION DOES SEEM TO BE THE MORE AGGRESSIVE OF THE SOLUTIONS THOUGH
WITH A DEEPER UPPER LOW AND MORE NORTHERLY PROGRESSION AFTER THE
MONDAY MORNING TIME FRAME. IN THE WAKE OF THIS FALL-LIKE LOOKING
SYSTEM, WILL BE ANOTHER NICE FEW DAYS AS HEIGHTS RISE AND SUBSIDENCE
SETS IN WITH SIGNIFICANT MOISTURE BEING PUSHED SOUTH.
HIGH TEMPS COOL BEHIND THE SYSTEM INTO THE UPPER 70S
AND ONLY CLIMB INTO THE MID 80S BY TUESDAY. LOWS MEANWHILE COULD
FLIRT WITH LOW 50S IN PARTS OF THE AREA BY TUESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1227 PM CDT TUE AUG 18 2015
ANY NEW TS DEVELOPMENT THIS AFTERNOON APPEARS TO BE MORE SCATTED
IN NATURE. SO ONLY HAVE CONFIDENCE TO KEEP A VCTS IN THE
TERMINALS. THINK THE TS CHANCES WILL DIMINISH QUICKLY ONCE THE
FRONT PASSES THROUGH, WHICH IS TIMED BASED ON THE RAP AND HRRR
PROGS. NOTICED THE MVFR COGS UPSTREAM ACROSS WESTERN NEB. FOR NOW
THE MODEL PROGS KEEP ANY CIGS ABOVE 3KFT, BUT WILL NEED TO MONITOR
THIS THROUGH THE EVENING.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...WOLTERS
LONG TERM...65/DRAKE
AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1227 PM CDT TUE AUG 18 2015
.UPDATE...
ISSUED AT 1227 PM CDT TUE AUG 18 2015
OVERALL THE FORECAST SEEMS TO BE UNFOLDING AS EXPECTED. IF
ANYTHING THE COLD FRONT IS A LITTLE MORE PROGRESSIVE THAN EARLIER
PROGGED, BUT THE HRRR AND RAP SEEM TO HAVE A GOOD REPRESENTATION
OF THE FRONT NOW. BECAUSE OF THIS THINK THE NAM IS AN OUTLIER WITH
THE ISOLATED CONVECTION IT TRIES TO DEVELOP AROUND 00Z. CURRENT
CONDITIONS AHEAD OF THE FRONT SHOW SOME WARMING WITH TEMPS NEAR
80 FROM SLN TO MHK. WITH THE INCREASING 0-6KM SHEAR AND SURFACE
BASED CAPE NOW AROUND 1000 J/KG, IT APPEARS AS THOUGH THERE IS A
RISK FOR SEVERE STORMS THROUGH THE AFTERNOON WITH THE COLD FRONT.
LOW LEVEL WINDS VEERED TO THE SOUTHWEST ARE NOT VERY CONDUCIVE FOR
MUCH OR A TORNADO RISK, BUT THERE COULD BE SOME DAMAGING WINDS OR
HAIL WITH THE MORE ORGANIZED STORMS.
UPDATE ISSUED AT 452 AM CDT TUE AUG 18 2015
RECENT OBSERVATIONS (ASOS AND RADAR), AS WELL AS RECENT MODEL HIGH
RES MODEL GUIDANCE HAVE PROMPTED A FORECAST UPDATE EARLY THIS
MORNING. CENTRAL KANSAS HAS SEEN THE DEVELOPMENT OF A STRONG
PRESSURE GRADIENT ON THE NORTH AND NORTHEAST SIDES OF THE INCOMING
CONVECTIVE CLUSTER. THE LOW LEVEL JET HAS STRENGTHENED IN THESE
AREAS AS WELL WITH 40 KTS AT ICT AND INDICATIONS BY MODEL AND
RADAR DATA OF STRONGER WINDS YET JUST NORTH AND NORTHEAST OF THE
CIRCULATION CENTER. IT APPEARS THAT THIS SYSTEM IS UNDERGOING A
DEEPENING OF THE LOW AND IS FORECAST TO CONTINUE DEEPENING AS IT
MOVES NORTHEAST THROUGH THIS MORNING. THIS HAS PROMOTED ENHANCED
WINDS VIA THE STRENGTHENING PRESSURE GRADIENT ALONG WITH SOME
INCREASED MIXING ON THE EDGE OF STRATIFORM PRECIP AND WITH
STRONGER CONVECTIVE AREAS. ONE CONCERN IS THAT AS THIS SYSTEM
MOVES OVER THE FORECAST AREA, LOW LEVEL MIXING MAY INCREASE A BIT
AFTER SUNRISE AND PROVIDE A PERIOD OF ENHANCED SURFACE WIND
SPEEDS DURING THE MORNING HOURS. CONFIDENCE IS NOT HIGH BUT IT
SEEMS PLAUSIBLE. FOR NOW FEEL THAT AN AREA OF 30+ MPH WINDS ARE
LIKELY BUT WOULD NOT BE SURPRISED TO SEE SOME AREAS OF 50+ AND
WILL BE WATCHING IT CLOSELY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 353 AM CDT TUE AUG 18 2015
A VERY COMPLEX AND POTENT STORM SYSTEM...ESPECIALLY FOR MID AUGUST
IN THIS PART OF THE COUNTRY...IS ORGANIZING AND MOVING INTO THE
PLAINS THIS MORNING. NOTABLE FEATURES INCLUDE LEAD SHORT WAVE
TROUGHS APPROACHING LAKE MICHIGAN, SOUTHWEST IOWA, AND ONE OF
PARTICULARLY INTEREST CROSSING OUT OF SOUTHWEST KANSAS EARLY THIS
MORNING. THE MAIN UPPER LEVEL TROUGH ENERGY WAS FOCUSED OVER WESTERN
SOUTH DAKOTA WITH ADDITIONAL ENERGY WELL UPSTREAM IN SOUTHERN
CANADA. EACH OF THESE PIECES OF ENERGY WAS DRIVING CONVECTIVE
CLUSTERS. THE CONVECTIVE COMPLEX OVER SOUTH CENTRAL KANSAS AT 3 AM
HAD A PARTICULARLY TIGHT SPIN TO IT WITH STRONG FOCUSED ASCENT IN
ADVANCE OF THE CIRCULATION AND RATHER STRONG SUBSIDENCE IN ITS WAKE.
ANOTHER WELL-ORGANIZED CONVECTIVE SYSTEM WAS MOVING ACROSS NORTHERN
NEBRASKA WITH SOME OF THE ENERGY APPARENTLY DRIVING MORE ISOLATED
CONVECTION AS FAR SOUTH AS NORTHWEST KANSAS. THIS ALSO SEEMED TO BE
TIED TO THE MAIN UPPER TROUGH AND SURGING COLD FRONT.
IN THE NEAR TERM, EXPECT THE CONVECTIVE COMPLEX OVER SOUTH CENTRAL
KANSAS TO BUILD TOWARD THE EAST AND NORTHEAST THIS MORNING AND
PROVIDE RAIN AND EMBEDDED THUNDERSTORMS TO MUCH OF THE FORECAST AREA
BEFORE NOON. AND INTERESTING FEATURE WITH THIS IS A VERY STRONG
PRESSURE GRADIENT WITH A STRONG MESO LOW CENTERED NORTH OF ELLSWORTH
AND A MESO HIGH UNDER THE CENTER OF THE PRECIPITATION SHIELD. THIS
FEATURE...POTENTIALLY WITH SOME ASSISTANCE FROM ENHANCED DOWNWARD
MOTION ON THE EDGE OF PRECIPITATION...WAS RESULTING IN SOME STRONG
WIND GUSTS OF 30 TO 45 KTS. THESE WINDS WOULD SEEM LIKELY TO
CONTINUE INTO THE ABILENE AND PERHAPS MANHATTAN AREAS WITH
TIME...ALTHOUGH HOW LONG THEY PERSIST AT THIS STRENGTH IS A BIT OF A
QUESTION MARK. OTHER THAN THESE STRONGER WINDS, THIS RAIN AND
EMBEDDED STORMS ARE EXPECTED TO BE RATHER BENIGN, ALTHOUGH WILL WANT
TO KEEP AN EYE ON ANY BOWING SEGMENTS IN THE SOUTHEAST QUADRANT OF
THE SYSTEM AS IT SHIFTS EAST. THIS PRECIPITATION IS LIKELY TO SHIFT
EAST OF THE FORECAST AREA BY EARLY AFTERNOON.
THE AFTERNOON FORECAST REMAINS INTERESTING. EXPECT SUBSIDENCE IN THE
WAKE OF THE MORNING PRECIP AND THIS SHOULD RESULT IN A BREAK IN RAIN
FOR MOST OF THE AREA. QUESTIONS ARISE WHETHER THIS SUBSIDENCE WILL
BE STRONG ENOUGH TO CREATE BREAKS IN THE CLOUDS, AND AT THIS POINT
FEEL THAT CLOUDS WILL LIKELY DOMINATE THE DAY. THERE IS ALSO SOME
CHANCE FOR SCATTERED CONVECTION TO START UP SHORTLY IN THE WAKE OF
THE MORNING ACTIVITY GIVEN ADDITIONAL WEAKER SHORT WAVE ENERGY
INCOMING. THE MAIN SHOW WILL BE ALONG A PRE-FRONTAL TROUGH OR
POSSIBLY THE ACTUAL COLD FRONT THIS AFTERNOON, WITH STORMS LIKELY TO
DEVELOP BY 3 PM. THERE ARE TWO MAIN QUESTIONS AT THIS TIME...1 IS
WHETHER THE STORMS WILL DEVELOP ON THE COLD FRONT OR ON THE PRE-
FRONTAL TROUGH/WIND SHIFT FROM SSE TO SW THAT MOST MODEL GUIDANCE IS
SUGGESTING WILL EXIST...AND THE SECOND QUESTION IS HOW MUCH
INSTABILITY WILL EXIST FOR STORMS TO WORK WITH. WOULD LIKE TO SEE
TEMPERATURES CLIMB INTO THE LOWER 80S FOR SEVERE POTENTIAL TO EXIST,
ALTHOUGH 80 IS NOT A HARD CUTOFF. THIS SEEMS POSSIBLE EVEN WITH
CLOUD COVER GIVEN PERSISTENT SOUTH WIND AND LOW LEVEL MIXING.
ASSUMING THAT TEMPERATURES WARM AND 1000-2000 J/KG OF MLCAPE ARE
PRESENT, THEN SEE POTENTIAL FOR SOME SUPERCELL STRUCTURES AS WELL AS
BOWING SEGMENTS TO DEVELOP GIVEN INCREASING DEEP WIND SHEAR AND
LARGELY UNIDIRECTIONAL SHEAR PROFILES. DAMAGING WINDS WOULD SEEM TO
BE THE PRIMARY HAZARD GIVEN THE WIND PROFILES ALTHOUGH ANY SUPERCELL
STRUCTURES WOULD POINT TO ENHANCED LARGE HAIL POTENTIAL. CAN NOT
COMPLETELY RULE OUT A TORNADO GIVEN MODERATE 0-1 KM WIND SHEAR BUT
THE LOW LEVEL FLOW IS QUITE VEERED AND FAIRLY UNIDIRECTIONAL SO THE
POTENTIAL APPEARS MINIMAL AND PROBABLY CONTINGENT ON A WELL
DEVELOPED SUPERCELL. KEEP IN MIND THAT IT IS ENTIRELY POSSIBLE THAT
THESE AFTERNOON STORMS LACK INSTABILITY AND REMAIN DISORGANIZED AND
SUB-SEVERE...BUT FOR NOW WOULD AT LEAST PLAN ON A FEW STRONG TO
SEVERE STORMS.
STORMS WILL PUSH EAST OF THE FORECAST AREA BY MID EVENING WITH
LINGERING SHOWERS POSSIBLE ESPECIALLY IN EAST CENTRAL KANSAS. THE
COLD FRONT WILL MOVE THROUGH WITH MUCH COOLER TEMPERATURES MOVING IN
ALONG WITH NORTHWEST WINDS. LOWS SHOULD BE IN THE 50S BY SUNRISE ON
WEDNESDAY.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 353 AM CDT TUE AUG 18 2015
BY WEDNESDAY MORNING, POST FRONTAL SHOWERS AND THUNDERSTORMS MAY BE
LINGERING ACROSS FAR EAST CENTRAL KANSAS, QUICKLY EXITING SOUTHEAST
BY LATE MORNING. WHILE THE GFS IS ADVERTISING THIS FEATURE FURTHER
SOUTH COMPARED TO PREVIOUS RUNS, THE NAM, GEM, AND ECMWF ARE STILL
INDICATING AN ADDITIONAL VORT LOBE TO ROTATE THROUGH THE UPPER
TROUGH AXIS DURING THE LATE AFTERNOON PERIOD. SUBSIDENCE WILL ALSO
BE INCREASING FROM THE NORTH SO AREAS ALONG AND SOUTH OF I70 MAY SEE
A MIX OF RAIN SHOWERS OR DRIZZLE AS RIDGING BUILDS IN WEDNESDAY
EVENING. MUCH COOLER HIGHS ARE IN STORE AS THE STEADY COLD ADVECTION
INCREASES FROM THE NORTHWEST WITH GUSTS UP TO 20 MPH AT TIMES. HIGHS
IN THE LOWER TO MIDDLE 70S ARE LIKELY. HIGH PRESSURE INFLUENCE
WEDNESDAY EVENING HELP TO CLEAR SKIES AND QUICKLY COOL OVERNIGHT
LOWS INTO THE MID 50S. THERE IS POTENTIAL FOR PATCHY FOG DEPENDING
ON HOW QUICKLY SKIES CLEAR AND WHERE PRECIP FALLS DURING THE DAY.
SKIES CLEAR AND DRY CONDITIONS RETURN TEMPORARILY AS BROAD TROUGHING
STRETCHES THROUGH MUCH OF THE CONUS. A WEAK EMBEDDED WAVE FROM THE
SOUTHWEST INTERACTS WITH A PLUME OF GULF MOISTURE OVER SOUTHERN
TEXAS, LIFTING NORTHEAST TOWARDS THE CWA ON FRIDAY AFTERNOON AND
EVENING. THE GFS HAS CONTINUED TO BE THE AMPLIFIED SOLUTION WHILE
THE ECMWF AND GEM DEPICT WEAKER FORCING WITH MORE SCATTERED
CONVECTION, FOCUSED FROM EAST CENTRAL KS INTO MO. THERE APPEARS TO
BE A BRIEF BREAK IN PRECIP ON SATURDAY AS SOUTHERLY WINDS BECOME
GUSTY IN RESPONSE TO A DEEPENING SFC LOW OVER THE WESTERN HIGH
PLAINS. ANOTHER STOUT NEGATIVELY TROUGH IS PROGGED TO DIVE SOUTHEAST
TOWARDS THE AREA SATURDAY AFTERNOON INTO EARLY SUNDAY. A FEW STRONG
STORMS MAY BE POSSIBLE WITH ELEVATED INSTABILITY INCREASING THROUGH
THE DAY AND A DECENT WIND PROFILE IN FORECAST SOUNDINGS. AFTER
READINGS NEAR 90 ON SATURDAY, HIGHS STEADILY FALL BACK AGAIN TO NEAR
80 DEGREES ON SUNDAY INTO EARLY NEXT WEEK. STRONG RIDGING CEASES
PRECIP CHANCES THROUGH THE FIRST HALF OF NEXT WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1227 PM CDT TUE AUG 18 2015
ANY NEW TS DEVELOPMENT THIS AFTERNOON APPEARS TO BE MORE SCATTED
IN NATURE. SO ONLY HAVE CONFIDENCE TO KEEP A VCTS IN THE
TERMINALS. THINK THE TS CHANCES WILL DIMINISH QUICKLY ONCE THE
FRONT PASSES THROUGH, WHICH IS TIMED BASED ON THE RAP AND HRRR
PROGS. NOTICED THE MVFR COGS UPSTREAM ACROSS WESTERN NEB. FOR NOW
THE MODEL PROGS KEEP ANY CIGS ABOVE 3KFT, BUT WILL NEED TO MONITOR
THIS THROUGH THE EVENING.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
UPDATE...WOLTERS
SHORT TERM...BARJENBRUCH
LONG TERM...BOWEN
AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1116 PM MDT MON AUG 17 2015
.UPDATE...
ISSUED AT 504 PM MDT MON AUG 17 2015
ADVANCING COLD FRONT/COLD POOL FROM THE NORTHEAST HAS CLEARED ST
FRANCIS AND COLBY AND RAPIDLY HEADING TOWARDS THE GLD AREA. IN
ADDITION TO THE WIND SHIFT AND EVEN MORE INCREASED LOW LEVEL
SHEAR...MESOANALYSIS INDICATES STRONG CINH IN COOLER AIR TO THE
NORTH. THINK THIS WILL FOR AT LEAST A WHILE ACT AS A NORTHERN
LIMIT TO SFC BASED CONVECTION AND HAVE HIGHLIGHTED AND INCREASED
POPS IN AREAS TO THE SOUTH OF AFOREMENTIONED FEATURE. ALTHOUGH
STORMS ARE MOVING...RAINFALL RATES AROUND AN INCH AND A HALF PER
HOUR HAVE BEEN OBSERVED KEEPING HEAVY RAIN SIG THREAT. QUICK
MOTION SHOULD LIMIT FLOOD POTENTIAL AND AT THIS TIME HAVE OPTED
AWAY FROM ANY LARGE SCALE WATCH.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 250 PM MDT MON AUG 17 2015
EARLY AFTERNOON WV IMAGERY AND RAP UPPER LEVEL ANALYSIS SHOW
STRENGTHENING TROUGH ACROSS MONTANA WITH SHARP PV HEIGHT ANOMALY
DIGGING INTO NORTHWESTERN WYOMING. DIFFLUENT FLOW IS IN PLACE
ACROSS NORTHERN COLORADO WITH INCREASING DIVERGENT SIGNATURE
AHEAD OF APPROACHING UPPER LEVEL JET. AT THE SURFACE A STATIONARY
FRONT EXTENDS FROM NORTH CENTRAL KANSAS TO SOUTHEAST
COLORADO...ACROSS THE SOUTHEAST PART OF OUR CWA...WITH A WEAK
SURFACE TROUGH AXIS EXPENDING ACROSS THE NW PART OF OUR FORECAST
AREA.
THUNDERSTORMS SHOULD INITIATE ACROSS EASTERN COLORADO THIS
AFTERNOON WITH ACTIVITY INCREASING IN COVERAGE AND SPREADING EAST
INTO OUR CWA THROUGH THE EVENING/OVERNIGHT. BEST FORCING IS
ADVERTISED 03-06Z OVER OUR CWA AND QUICKLY TRANSITIONS EASTWARD
THROUGH TUESDAY MORNING. AS THE UPPER LOW DEEPENS AND EVENTUALLY
CLOSES OFF OVER NEBRASKA DRY SLOT/SUBSIDENT REGION WILL MOVE OVER
OUR CWA WHICH SHOULD RAPIDLY DECREASE ANY SHOWER/THUNDERSTORM
CHANCES. STRONG COLD FRONT WILL DROP DOWN ACROSS THE REGION
TUESDAY MORNING AND COMBINED WITH INCREASING SUBSIDENCE BRING
MILD/WINDY (VERY FALL-LIKE) CONDITIONS TO OUR CWA. THERE MAY ALSO
BE A REDEVELOPMENT OF DENSE FOG/LOW STRATUS OVER SW NEBRASKA
DEPENDING ON THUNDERSTORM ACTIVITY/MIXING AND FRONTAL TIMING.
REGARDING SEVERE POTENTIAL TONIGHT...RAP ANALYSIS SHOWS SB CAPE
AXIS 2500-3500 J/KG AND DEEP BULK EFFECTIVE SHEER VALUES 40-50KT
ACROSS EASTERN COLORADO. CONSIDERING THE DEEP LAYER SHEER AND
INSTABILITY WE ARE ANTICIPATING ORGANIZED SUPERCELLS DEVELOPING
LATE THIS AFTERNOON AND SLOWLY PROGRESSING EASTWARD (MEAN STORM
MOTIONS 10-20KT). THERE IS A WINDOW WITH LOW LEVEL TURNING ALONG
SURFACE TROUGH AXIS FOR TORNADOES WITH MORE ORGANIZED CELLS...WITH
PRIMARY THREAT VERY LARGE HAIL (2"+) AND DAMAGING WINDS. AS THIS
ACTIVITY ORGANIZES INTO A MCS/THUNDERSTORM CLUSTER TORNADO THREAT
SHOULD DIMINISH. TORNADO WATCH 490 IS CURRENTLY IN EFFECT FOR OUR
EASTERN COLORADO COUNTIES...AND PATTERN IS BEING MONITORED FOR
ANY OTHER POSSIBLE SEVERE WATCHES AS THIS UNFOLDS THIS
AFTERNOON/EVENING.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 156 PM MDT MON AUG 17 2015
JET MAX ROTATING AROUND BACK OF THE UPPER TROUGH WILL BRING
SCATTERED SHOWERS TO THE AREA TUESDAY NIGHT THROUGH WEDNESDAY
MORNING UNDER THE DIVERGENT LEFT EXIT REGION. MODEL QPF IS
LIGHT...GENERALLY BETWEEN A TENTH AND A QUARTER OF AN INCH...BUT
RATHER WIDESPREAD SO POPS MAY NEED TO BE INCREASED IF THOSE TRENDS
CONTINUE. POINT FORECAST SOUNDINGS ACTUALLY SHOW ICE IN THE COLUMN
BUT THE SURFACE BASED WARM LAYER EXTENDS TO AROUND 6KFT AGL WHICH
WILL BE MORE THAN SUFFICIENT TO KEEP ANY KIND OF SNOW FROM
REACHING THE GROUND. LOW TEMPERATURES A BIT TRICKY...WITH CLOUDS
POTENTIALLY KEEPING THEM FROM REACHING THE UPPER 40S BUT IF THE
RAIN IS PROLONGED MIGHT WET BULB DOWN TO NEAR THAT ANYWAY. EITHER
WAY IT WILL BE A RATHER CHILLY MORNING FOR MID AUGUST.
UPPER TROUGH WILL MOVE OUT WEDNESDAY AFTERNOON WITH NORTHWEST
FLOW ALOFT THROUGH THE END OF THE WEEK. PRECIPITATION CHANCES
DURING THAT TIME WILL BE SLIM TO NONE WITH NO UPPER SHORTWAVES IN
THE MODELS AND LIMITED MOISTURE AVAILABLE. TEMPERATURES WILL
REBOUND QUICKLY AFTER THE MIDWEEK COOL DOWN WITH ABOVE NORMAL
HIGHS BY FRIDAY. THE UPPER FLOW WILL TRANSITION TO ZONAL AND THEN
SOUTHWEST OVER THE WEEKEND AS ANOTHER TROUGH DIGS INTO THE
NORTHERN ROCKIES. THE NEXT BEST CHANCE FOR THUNDERSTORMS WILL BE
SATURDAY AFTERNOON/EVENING AS DYNAMICS AND SURFACE COLD FRONT
ASSOCIATED WITH THAT SYSTEM MOVE THROUGH THE CENTRAL PLAINS. A
LITTLE EARLY...BUT RIGHT NOW BEST COMBINATION OF INSTABILITY AND
SHEAR WILL BE CONFINED TO EASTERN PARTS OF THE FORECAST
AREA...NORTON TO GOVE...WHICH WOULD BE THE FAVORED AREAS FOR ANY
SEVERE THREAT. IF THAT TIMING VERIFIES SUNDAY AND MONDAY WILL BE
DRY AND A LITTLE COOLER.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1111 PM MDT MON AUG 17 2015
DIFFICULT...POTENTIAL LONG DURATION IFR TO LIFR CONDITIONS
EXPECTED OVERNIGHT PRIOR TO ARRIVAL OF STRONG COLD FRONT SHORTLY
AFTER SUNRISE. ONCE THE FRONT PASSES...WINDS WILL SHIFT TO THE
NORTH WITH VISBY AND CIGS RISING QUICKLY BEHIND GUSTY NORTHERLY
WINDS. BEFORE THE FROPA...MCK WILL LIKELY REMAIN AT OR NEAR LIFR
CONDITIONS THROUGH THE NIGHT AS LARGE AREA OF STRATUS DEVELOPED
OVER THE AREA. MAY SEE SOME IMPROVEMENT BTWN 08-12Z WITH SHOWERS
MOVING THROUGH...BUT SHOULD NOT BE LONG LIVED. GLD IN A MUCH MORE
DIFFICULT POSITION AS COLD FRONT AS DRIFTED BACK AND FORTH ACROSS
THE AREA ALTHOUGH IT IS NOW ADVANCING SOUTH AGAIN. NOT ONLY DOES
THIS MAKE WIND FORECAST HIGHLY UNCERTAIN...BUT MOIST FOG
PRECONDITIONED AIR EXISTS TO THE NORTH OF THE FRONT...WITH MUCH
DRIER AIR TO THE SOUTH. HAVE ALREADY SEEN CONDITIONS VARY BTWN
LIFR AND VFR IN THE PAST FEW HOURS...BUT TEND TO THINK CURRENT VFR
CONDITIONS WILL FALL FOR A FEW HOURS BEFORE SFC WINDS BECOME
WESTERLY.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JRM
SHORT TERM...DR
LONG TERM...024
AVIATION...JRM
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
1055 PM EDT WED AUG 19 2015
.UPDATE...
ISSUED AT 1055 PM EDT WED AUG 19 2015
CONVECTION HAS FILLED IN ACROSS EASTERN TENNESSEE AND PORTIONS OF
SOUTHEAST KENTUCKY OVER THE PAST HOUR. HAVE INCREASED POPS TO
ACCOUNT FOR THIS ACTIVITY. MORE DEVELOPMENT IS ALSO OCCURRING BACK
ACROSS WESTERN KENTUCKY OUT AHEAD OF THE APPROACHING COLD FRONT.
HAVE MADE SOME MINOR ADJUSTMENTS IN THE POPS THROUGH THE REST OF
THE NIGHT...BASED ON THE LATEST RADAR AND HIGHER RESOLUTION MODEL
TRENDS. THIS WILL KEEP MAINLY LIKELY POPS ACROSS THE AREA THROUGH
DAWN AS THE FRONT APPROACHES FROM THE WEST AND NORTHWEST.
UPDATE ISSUED AT 819 PM EDT WED AUG 19 2015
FRESHENED UP THE HOURLY POPS ACCORDING TO THE LATEST RADAR TRENDS.
A CLUSTER OF SHOWERS AND STORMS IS CURRENTLY ALIGNED NEAR THE I-75
CORRIDOR...WITH MORE WIDESPREAD CONVECTION DOWN IN TENNESSEE. THE
LATEST HRRR YIELDS A GENERAL WEAKENING TREND THROUGH EARLY THIS
EVENING...WITH OUR SOUTHWEST SEEING THE BEST AREAL COVERAGE
THROUGH THIS EVENING. HAVE USED A BLEND OF THE HRRR AND GENERAL
EXTRAPOLATION FROM THE MOSAIC RADAR FOR THE POPS OVER THE NEXT
SEVERAL HOURS...BEFORE BLENDING INTO THE INHERITED FORECAST.
UPDATES HAVE BEEN SENT.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 311 PM EDT WED AUG 19 2015
AREA OF LOW PRESSURE CONTINUES TO PUSH NORTHEAST ACROSS THE
NORTHERN GREAT LAKES...WITH A TRAILING COLD FRONT STRETCHING BACK
SOUTH ACROSS ILLINOIS AND MISSOURI THIS AFTERNOON. THIS FRONT WILL
BE THE FOCUS FOR OUR WEATHER OVER THE NEXT 18 TO 24 HOURS AS IT
CONTINUES TO PUSH EAST. PLENTY OF MOISTURE CONTINUES TO REMAIN
AHEAD OF THE ADVANCING FRONT...LEADING TO SCATTERED TO NUMEROUS
SHOWERS AND STORMS ACROSS MUCH OF THE OHIO RIVER VALLEY. ORGANIZED
AREA OF SHOWERS AND STORMS HAS JUST ABOUT CLEARED OUR NORTHEAST
COUNTIES...WITH A LULL SPREADING OVER THE AREA.
HOWEVER...ADDITIONAL ISOLATED SHOWERS AND A FEW STORMS ARE
STARTING OT POP UP IN SOUTH CENTRAL KENTUCKY. THIS ACTIVITY WILL
CONTINUE TO FILL IN AND DEVELOPMENT THROUGH THE EVENING.
HOWEVER...AS INSTABILITY DECREASES WITH SUNSET THIS EVENING...WE
COULD SEE MUCH OF THE ACTIVITY OUT THERE NOW DIE OFF EXCEPT FOR
THE MORE ORGANIZED CLUSTERS OF STORMS. FOR EASTERN
KENTUCKY...THERE DOESN`T APPEAR TO BE ANY ADDITIONAL ORGANIZED
STORMS HEADING OUR WAY...SO IT LOOKS LIKE WE SHOULD SEE A LULL
INTO THE OVERNIGHT HOURS. HOWEVER...COLD FRONT WILL MOVE LATE
TONIGHT AND AROUND DAYBREAK...WITH SHOWERS AND STORMS INCREASING
IN COVERAGE. THIS FRONT WILL CROSS THE AREA TOMORROW
MORNING...BEFORE EXITING BY THURSDAY AFTERNOON. SEVERE THREAT
SHOULD REMAIN LOW GIVEN THE FRONT COMING THROUGH DURING THE
MORNING HOURS WITH LACK OF STRONGER SURFACE INSTABILITY. AS THE
FRONT EXITS BY MID AFTERNOON ON THURSDAY...PRECIPITATION THREAT
WILL END. COOLER AND LESS HUMID CONDITIONS WILL SPREAD IN BEHIND
THE FRONT...SETTING THE STAGE FOR A MUCH COOLER NIGHT FOR THURSDAY
NIGHT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 311 PM EDT WED AUG 19 2015
THE WEATHER STARTS OUT FAIRLY BENIGN EARLY FRIDAY MORNING AS A SFC
HIGH PRESSURE BUILDS INTO THE REGION BEHIND A COLD FRONTAL PASSAGE.
THIS WILL ALLOW FOR COOLER...DRIER AIR TO FILTER INTO THE REGION
KEEPING CLOUDS TO A MINIMUM AND DEW POINTS IN THE 50S TO LOWER 60S.
IN FACT...FRIDAY WILL BE A BEAUTIFUL SUMMER DAY WITH HIGHS IN THE
MID TO UPPER 70S AND LOW HUMIDITY.
BY SUNDAY...AN UPPER LEVEL LOW DEVELOPS ALONG THE CANADIAN/US BORDER
MOVING MAINLY EWD. AN ASSOCIATED SFC LOW DEVELOPS PULLING A COLD
FRONT TO ITS SOUTH ACROSS THE CENTRAL U.S. ON MONDAY.
HOWEVER...THESE FEATURES SHOULD STAY WELL TO OUR NORTH AND LIMIT THE
FORCING...AND THE PRECIP...AS THE FRONT MOVES THROUGH EASTERN KY ON
MONDAY.
HIGH PRESSURE WILL BUILD INTO THE REGION ONCE AGAIN AFTER THE
FRONTAL PASSAGE ON MONDAY...ALLOWING FOR COOLER AND DRIER WEATHER TO
END THE PERIOD. TEMPERATURES THROUGHOUT THE EXTENDED WILL BE AT OR
BELOW NORMAL VALUES WITH HIGHS GENERALLY IN THE UPPER 70S AND LOW
80S...AND LOWS IN THE 50S TO LOW 60S.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 819 PM EDT WED AUG 19 2015
SCATTERED TO NUMEROUS CONVECTION WILL CONTINUE TO FIRE UP OUT
AHEAD OF AN APPROACHING COLD FRONT TONIGHT. LOZ AND SME WILL HAVE
THE BETTER CHANCE OF SEEING A DIRECT HIT FROM SHOWERS AND STORMS
THROUGH 06Z...WITH LESSER CHANCES ELSEWHERE. MAINLY VFR CONDITIONS
CAN BE EXPECTED...WITH THE EXCEPTION OF A DIRECT HIT FROM A
SHOWER OR STORM...WHERE TEMPORARY MVFR/IFR CONDITIONS ARE LIKELY.
AS THE FRONT GETS CLOSER TOWARDS DAWN...EXPECT SHOWERS AND
SCATTERED THUNDERSTORMS TO DEVELOP AND MOVE EAST ACROSS THE AREA
THROUGH THE LATE MORNING HOURS ON THURSDAY. CEILINGS WILL LOWER TO
MVFR STATUS...BEFORE GRADUALLY RAISING UP AND SCATTERING OUT FROM
WEST TO EAST IN THE AFTERNOON. SOUTH TO SOUTHWEST WINDS OF 5 TO 10
KTS...WITH GRADUALLY SHIFT TO THE WEST AND NORTHWEST WITH THE
FRONTAL PASSAGE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...KAS
LONG TERM...JVM
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
819 PM EDT WED AUG 19 2015
.UPDATE...
ISSUED AT 819 PM EDT WED AUG 19 2015
FRESHENED UP THE HOURLY POPS ACCORDING TO THE LATEST RADAR TRENDS.
A CLUSTER OF SHOWERS AND STORMS IS CURRENTLY ALIGNED NEAR THE I-75
CORRIDOR...WITH MORE WIDESPREAD CONVECTION DOWN IN TENNESSEE. THE
LATEST HRRR YIELDS A GENERAL WEAKENING TREND THROUGH EARLY THIS
EVENING...WITH OUR SOUTHWEST SEEING THE BEST AREAL COVERAGE
THROUGH THIS EVENING. HAVE USED A BLEND OF THE HRRR AND GENERAL
EXTRAPOLATION FROM THE MOSAIC RADAR FOR THE POPS OVER THE NEXT
SEVERAL HOURS...BEFORE BLENDING INTO THE INHERITED FORECAST.
UPDATES HAVE BEEN SENT.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 311 PM EDT WED AUG 19 2015
AREA OF LOW PRESSURE CONTINUES TO PUSH NORTHEAST ACROSS THE
NORTHERN GREAT LAKES...WITH A TRAILING COLD FRONT STRETCHING BACK
SOUTH ACROSS ILLINOIS AND MISSOURI THIS AFTERNOON. THIS FRONT WILL
BE THE FOCUS FOR OUR WEATHER OVER THE NEXT 18 TO 24 HOURS AS IT
CONTINUES TO PUSH EAST. PLENTY OF MOISTURE CONTINUES TO REMAIN
AHEAD OF THE ADVANCING FRONT...LEADING TO SCATTERED TO NUMEROUS
SHOWERS AND STORMS ACROSS MUCH OF THE OHIO RIVER VALLEY. ORGANIZED
AREA OF SHOWERS AND STORMS HAS JUST ABOUT CLEARED OUR NORTHEAST
COUNTIES...WITH A LULL SPREADING OVER THE AREA.
HOWEVER...ADDITIONAL ISOLATED SHOWERS AND A FEW STORMS ARE
STARTING OT POP UP IN SOUTH CENTRAL KENTUCKY. THIS ACTIVITY WILL
CONTINUE TO FILL IN AND DEVELOPMENT THROUGH THE EVENING.
HOWEVER...AS INSTABILITY DECREASES WITH SUNSET THIS EVENING...WE
COULD SEE MUCH OF THE ACTIVITY OUT THERE NOW DIE OFF EXCEPT FOR
THE MORE ORGANIZED CLUSTERS OF STORMS. FOR EASTERN
KENTUCKY...THERE DOESN`T APPEAR TO BE ANY ADDITIONAL ORGANIZED
STORMS HEADING OUR WAY...SO IT LOOKS LIKE WE SHOULD SEE A LULL
INTO THE OVERNIGHT HOURS. HOWEVER...COLD FRONT WILL MOVE LATE
TONIGHT AND AROUND DAYBREAK...WITH SHOWERS AND STORMS INCREASING
IN COVERAGE. THIS FRONT WILL CROSS THE AREA TOMORROW
MORNING...BEFORE EXITING BY THURSDAY AFTERNOON. SEVERE THREAT
SHOULD REMAIN LOW GIVEN THE FRONT COMING THROUGH DURING THE
MORNING HOURS WITH LACK OF STRONGER SURFACE INSTABILITY. AS THE
FRONT EXITS BY MID AFTERNOON ON THURSDAY...PRECIPITATION THREAT
WILL END. COOLER AND LESS HUMID CONDITIONS WILL SPREAD IN BEHIND
THE FRONT...SETTING THE STAGE FOR A MUCH COOLER NIGHT FOR THURSDAY
NIGHT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 311 PM EDT WED AUG 19 2015
THE WEATHER STARTS OUT FAIRLY BENIGN EARLY FRIDAY MORNING AS A SFC
HIGH PRESSURE BUILDS INTO THE REGION BEHIND A COLD FRONTAL PASSAGE.
THIS WILL ALLOW FOR COOLER...DRIER AIR TO FILTER INTO THE REGION
KEEPING CLOUDS TO A MINIMUM AND DEW POINTS IN THE 50S TO LOWER 60S.
IN FACT...FRIDAY WILL BE A BEAUTIFUL SUMMER DAY WITH HIGHS IN THE
MID TO UPPER 70S AND LOW HUMIDITY.
BY SUNDAY...AN UPPER LEVEL LOW DEVELOPS ALONG THE CANADIAN/US BORDER
MOVING MAINLY EWD. AN ASSOCIATED SFC LOW DEVELOPS PULLING A COLD
FRONT TO ITS SOUTH ACROSS THE CENTRAL U.S. ON MONDAY.
HOWEVER...THESE FEATURES SHOULD STAY WELL TO OUR NORTH AND LIMIT THE
FORCING...AND THE PRECIP...AS THE FRONT MOVES THROUGH EASTERN KY ON
MONDAY.
HIGH PRESSURE WILL BUILD INTO THE REGION ONCE AGAIN AFTER THE
FRONTAL PASSAGE ON MONDAY...ALLOWING FOR COOLER AND DRIER WEATHER TO
END THE PERIOD. TEMPERATURES THROUGHOUT THE EXTENDED WILL BE AT OR
BELOW NORMAL VALUES WITH HIGHS GENERALLY IN THE UPPER 70S AND LOW
80S...AND LOWS IN THE 50S TO LOW 60S.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 819 PM EDT WED AUG 19 2015
SCATTERED TO NUMEROUS CONVECTION WILL CONTINUE TO FIRE UP OUT
AHEAD OF AN APPROACHING COLD FRONT TONIGHT. LOZ AND SME WILL HAVE
THE BETTER CHANCE OF SEEING A DIRECT HIT FROM SHOWERS AND STORMS
THROUGH 06Z...WITH LESSER CHANCES ELSEWHERE. MAINLY VFR CONDITIONS
CAN BE EXPECTED...WITH THE EXCEPTION OF A DIRECT HIT FROM A
SHOWER OR STORM...WHERE TEMPORARY MVFR/IFR CONDITIONS ARE LIKELY.
AS THE FRONT GETS CLOSER TOWARDS DAWN...EXPECT SHOWERS AND
SCATTERED THUNDERSTORMS TO DEVELOP AND MOVE EAST ACROSS THE AREA
THROUGH THE LATE MORNING HOURS ON THURSDAY. CEILINGS WILL LOWER TO
MVFR STATUS...BEFORE GRADUALLY RAISING UP AND SCATTERING OUT FROM
WEST TO EAST IN THE AFTERNOON. SOUTH TO SOUTHWEST WINDS OF 5 TO 10
KTS...WITH GRADUALLY SHIFT TO THE WEST AND NORTHWEST WITH THE
FRONTAL PASSAGE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...KAS
LONG TERM...JVM
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS JACKSON KY
ISSUED BY NATIONAL WEATHER SERVICE WILMINGTON OH
912 AM EDT TUE AUG 18 2015
.UPDATE...
ISSUED AT 905 AM EDT TUE AUG 18 2015
MINOR TWEAKS TO ONGOING FORECAST. SCT-BKN BANDS OF SHOWERS WILL
CONTINUE TO SPREAD NORTHEAST ACROSS ERN KY THROUGH THIS MORNING
INTO EARLY AFTERNOON BEFORE DECREASING SOMEWHAT AS THE AFTN WEARS
ON. STILL A VERY MOIST AIRMASS IN PLACE BUT RAP ANALYSIS AND WATER
VAPOR LOOPS INDICATE THE STRONGEST OF THE SHORTWAVE ENERGY
SHIFTING THROUGH ERN KY AND ERN OHIO MOVING OUT OF THE AREA...SO
WOULD EXPECT ANYTHING THIS AFTERNOON WILL BE LOOSELY FOCUSED AND
TIED MORE DIRECTLY TO POCKETS OF DIABATIC HEATING AND LOCALIZED
CONVERGENCE. THUS HAVE 50-65% RAIN CHANCES THIS MORNING DWINDLING
BACK TO 15-25% BY MID-LATE AFTN. WE MAY BE A BIT OPTIMISTIC THAT
TEMPS WILL MAKE THE LOWER 80S IN THE LOWLANDS THIS AFTN...CURRENT
VIS LOOPS INDICATE QUITE A BIT OF CLOUDS OVER THE AREA AND
UPSTREAM...SO WILL WATCH THIS FOR THE POTENTIAL NEED OF DROPPING
BACK A COUPLE OF DEGREES FOR THESE HIGHS. PULLED FOG OUT OF THE
FORECAST AS VSBYS HAVE IMPROVED SOMEWHAT OVER EARLIER VALUES.
UPDATE ISSUED AT 655 AM EDT TUE AUG 18 2015
JUST SENT OUT AN UPDATED VERSION OF THE ZONE FORECAST TEXT
PRODUCT THAT THE WILMINGTON WEATHER OFFICE HAD TO ISSUE FOR US
EARLIER THIS MORNING. A MAJOR COMMS OUTAGE OVERNIGHT KEPT US FROM
BEING ABLE TO ISSUE ANY OF OUR OWN PRODUCTS BETWEEN 1 AND 6 AM.
THE NEW FORECAST UPDATE WILL REFLECT INCREASING COVERAGE OF
SHOWERS AND STORMS THIS MORNING AS SOME ENERGY AND MOISTURE FROM
THE GULF OF MEXICO MAKE THEIR WAY INTO THE FORECAST AREA. THE NEW
FORECAST WILL CONTINUE TO MENTION EARLY MORNING FOG AND WILL NEED
TO BE UPDATED AGAIN AROUND 9 AM.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 508 AM EDT TUE AUG 18 2015
FAIRLY WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS ARE
PERSISTING THIS MORNING ACROSS FAR EASTERN KENTUCKY WITH ISOLATED
TO SCATTERED LIGHT SHOWERS ELSEWHERE ACROSS THE AREA. THIS IS ALL
ASSOCIATED WITH A WEAKENING MID LEVEL SHORT WAVE THAT IS FORECAST
TO CONTINUE TO SHIFT OFF TO THE EAST THROUGH THE MORNING HOURS.
THIS SHOULD LEAD TO A DECREASING TREND IN COVERAGE THROUGH THE
FIRST PART OF THE DAY. HOWEVER...IN A CONTINUED SOUTHWESTERLY
MID/UPPER LEVEL FLOW PATTERN...SEVERAL WEAK VORTS WILL LIFT EAST
NORTHEAST ACROSS THE TENNESSEE VALLEY LATER TODAY AND INTO
TONIGHT. THIS WILL RESULT IN SOME LINGERING CHANCES FOR
PRECIPITATION INTO TONIGHT...ESPECIALLY ACROSS FAR SOUTHEAST
PORTIONS OF KENTUCKY. HIGHS TODAY WILL RANGE FROM THE UPPER 70S
ALONG THE VIRGINIA/KENTUCKY BORDER TO THE LOWER 80S ELSEWHERE
ACROSS THE AREA. LOWS TONIGHT WILL GENERALLY BE IN THE UPPER 60S.
A STRENGTHENING LOW PRESSURE SYSTEM WILL MOVE INTO THE WESTERN
GREAT LAKES WEDNESDAY INTO THURSDAY ALLOWING FOR THE UPPER LEVEL
TROUGH OVER THE MISSISSIPPI VALLEY TO PIVOT EASTWARD INTO THE
UPPER OHIO VALLEY. THIS WILL HELP DRIVE A COLD FRONT THROUGH THE
REGION LATE WEDNESDAY NIGHT AND INTO THURSDAY. AHEAD OF
THIS...EXPECT AN INCREASING CHANCE OF SHOWERS AND THUNDERSTORMS
WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. PCPN SHOULD THEN BEGIN
TO TAPER OFF FROM THE WEST THROUGH THE DAY ON THURSDAY AS SOME
DRIER AIR WORKS IN BEHIND THE FRONT. EXPECT HIGHS ON WEDNESDAY IN
THE LOW TO MID 80S...COOLING OFF TO THE UPPER 70S TO LOWER 80S
FOR THURSDAY.
.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 508 AM EDT TUE AUG 18 2015
SURFACE HIGH PRESSURE WILL BUILD INTO THE REGION FRIDAY INTO
SATURDAY. THIS WILL RESULT IN DRY CONDITIONS WITH HIGHS IN THE
UPPER 70S TO LOWER 80S FOR FRIDAY...WARMING INTO THE LOW TO MID
80S FOR SATURDAY.
MID LEVEL SHORT WAVE ENERGY WILL MOVE ACROSS THE NORTHERN PLAINS
AND INTO THE GREAT LAKES REGION SUNDAY INTO MONDAY. THIS WILL
HELP DRIVE AN ASSOCIATED COLD FRONT ACROSS THE APPALACHIANS LATE
SUNDAY NIGHT. INCREASING MOISTURE AHEAD OF THE FRONT WILL LEAD TO
A CHANCE OF SHOWERS AND THUNDERSTORMS PRIMARILY LATER SUNDAY
AFTERNOON AND INTO SUNDAY NIGHT. DRIER AIR WILL THEN FILTER IN
BEHIND THE FRONT FOR MONDAY. EXPECT HIGHS IN THE MID TO POSSIBLY
UPPER 80S ON SUNDAY AND THEN MAINLY THE LOWER 80S FOR MONDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 655 AM EDT TUE AUG 18 2015
THE 12Z TAFS WILL BEGIN BY ADDRESSING FOG AT JKL...LOZ...AND SYM
EARLY THIS MORNING. ANY REMAINING FOG SHOULD BE PRETTY MUCH GONE
BY 9 AM. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL BE
MOVING INTO THE AREA EARLY THIS MORNING...AND WILL BE INCREASING
IN COVERAGE THROUGH OUT THE MORNING. THE TAF SITES COULD
EXPERIENCE MVFR CONDITIONS AS A SHOWER OR STORM MOVES PAST. THE
RAIN IS EXPECTED TO TAPER OFF QUICKLY AFTER 2 OR 3Z TONIGHT.
EXTENSIVE CLOUD COVER AND PERSISTENT LIGHT WINDS SHOULD KEEP FOG
FORMATION AT A MINIMUM OVERNIGHT INTO EARLY WEDNESDAY MORNING.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BINAU /WFO ILN/
SHORT TERM...AR
LONG TERM...HAL
AVIATION...AR
AREA FORECAST DISCUSSION
NWS NEW ORLEANS LA
317 PM CDT TUE AUG 18 2015
. DISCUSSION... A REPEAT OF TEMPERATURES STRUGGLING TO REACH 90
DEGREES HAS OCCURRED AS THE RESULT OF ANOTHER DAY FILLED WITH
PLENTIFUL CLOUDCOVER AND CONVECTION. A SHORTWAVE IMPULSE...
ORIGINATING IN THE SOUTHWEST GULF OF MEXICO...HAS BEEN AND IS
STILL PASSING OVER THE REGION FROM SW TO NE. THE HRRR HAS DONE AN
OUTSTANDING JOB ON CONVECTIVE INITIATION THIS MORNING AND
CONTINUED GENERAL PRECIP OUTPUT. SO BASED ON THIS MODEL AND
AGREEMENT FROM MEDIUM RANGE MODELS...SHOWERS AND THUNDERSTORMS
SHOULD BEGIN TO TAPER OFF SOMETIME AROUND 00Z TO 02Z. ISOLATED
COASTAL SHOWERS COULD PERSIST OVERNIGHT WITH SOME INLAND INTRUSION
AFTER 09Z.
MODELS INDICATE THAT AN UPPER LEVEL TROUGH WILL DIP DOWN INTO THE
UPPER MISSISSIPPI VALLEY TONIGHT AND SWING ACROSS THE GREAT LAKES
THROUGH THURSDAY. A COLD FRONT ASSOCIATED WITH THIS TROUGH WILL MOVE
SOUTH ACROSS THE COUNTRY WED AND THURS BUT STALL WELL NORTH OF THE
AREA. DESPITE THIS...ABUNDANT MOISTURE WILL CONTINUE TO FLOW IN
TOWARDS THAT BOUNDARY AND ANY UPPER LEVEL HEIGHTS WILL CONTINUE TO
LOWER. THAT COMBINATION WILL BE CONDUCIVE FOR NUMEROUS SHOWERS AND
STORMS THROUGHOUT THE REST OF THIS WEEK. THUS WILL KEEP LIKELY POPS
THROUGH AT LEAST FRIDAY.
A GRADUALLY DRYING OUT WILL TAKE PLACE GOING INTO THE WEEKEND AS THE
UPPER TROUGH TO THE NORTH SHIFTS EAST AND WEAK HIGH PRESSURE TRIES
TO BUILD IN.
MEFFER
&&
.AVIATION...
SCATTERED SHOWERS AND THUNDERSTORMS WILL ONCE AGAIN BE POSSIBLE
ACROSS ALL OF SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI TODAY AND
TOMORROW. HAVE VCTS WORDING IN PLACE THROUGH 00Z FOR ALL OF THE
TERMINALS TO REFLECT THE RISK OF CONVECTION. IF A THUNDERSTORM
THREATENS A TERMINAL...AN HOUR OR LESS OF IFR VISIBILITY
RESTRICTIONS DUE TO HEAVY RAINFALL CAN BE EXPECTED. OUTSIDE OF THE
CONVECTIVE ACTIVITY...A BROKEN CU FIELD RANGING FROM 3500 TO 5000
FEET CAN BE EXPECTED THROUGH THE DAY. AFTER 00Z...THE CONVECTION
SHOULD DISSIPATE AND EXPECT VFR CONDITIONS TO PREVAIL THROUGH AROUND
10Z. AFTER 10Z...SOME LOW STRATOCU RANGING FROM 1500 TO 2500 FEET
SHOULD DEVELOP AROUND THE BASE OF A WEAK ELEVATED INVERSION. EXPECT
THESE MVFR CEILINGS TO PERSIST THROUGH AROUND 15Z BEFORE LIFTING
ABOVE 3000 FEET. SCATTERED SHOWERS WILL ALSO BE POSSIBLE AFTER
12Z...AND HAVE VCSH WORDING IN PLACE TO REFLECT THIS RISK OF DEEP
TROPICAL MOISTURE AND A WEAK TROUGH OF LOWER PRESSURE LINGERS OVER
THE REGION. 32
&&
.MARINE...
MAIN ISSUE FOR MARINERS THROUGH AT LEAST THURSDAY WILL BE
THE DEVELOPMENT OF SCATTERED TO NUMEROUS THUNDERSTORMS...WITH THE
POTENTIAL FOR WINDS GUSTING ABOVE 30 KNOTS. OUTSIDE OF THE
THUNDERSTORM THREAT...GENERAL ONSHORE FLOW FROM THE SOUTH WILL
CONTINUE THROUGH THE END OF THE WORK WEEK. SHOULD BE ENOUGH OF A
GRADIENT TODAY AND WEDNESDAY TO PRODUCE 10-15 KNOT WINDS OVER THE
OPEN WATERS BEFORE RELAXING BELOW 10 KNOTS IN MOST AREAS FOR
THURSDAY THROUGH SATURDAY. AS EAST COAST TROF DEEPENS OVER THE
WEEKEND...OFFSHORE FLOW SHOULD DEVELOP ON SUNDAY. 35
&&
.DECISION SUPPORT...
DSS CODE....GREEN.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...NONE.
DECISION SUPPORT SERVICES (DSS) CODE LEGEND
GREEN = NO WEATHER IMPACTS THAT REQUIRE ACTION
BLUE = LONG FUSED WATCH/WARNING/ADVISORY IN EFFECT OR HIGH
VISIBILITY EVENT
YELLOW = HEIGHTENED IMPACTS WITH SHORT FUSED WATCH/WARNING/ADVISORY
ISSUANCES; RADAR SUPPORT
ORANGE = HIGH IMPACTS - SLIGHT TO MODERATE RISK SEVERE; NEARBY
TROPICAL EVENTS; HAZMAT OR OTHER LARGE EPISODES
RED = FULL ENGAGEMENT FOR MODERATE RISK SVR AND/OR DIRECT
TROPICAL THREATS; EVENTS OF NATIONAL SIGNIFICANCE
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 73 86 74 87 / 20 60 40 60
BTR 75 87 75 88 / 20 70 40 60
ASD 78 88 77 88 / 20 70 30 60
MSY 80 89 79 88 / 20 70 30 60
GPT 78 88 79 88 / 20 70 30 60
PQL 78 88 79 88 / 20 60 30 50
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
336 PM EDT TUE AUG 18 2015
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 335 PM EDT TUE AUG 18 2015
WV IMAGERY AND RAP ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM NRN HUDSON BAY INTO THE NRN PLAINS RESULTING IN A WSW FLOW INTO
THE NRN GREAT LAKES. A LINGERNIG AREA OF 700 MB FGEN AND WEAK
WAA/ISENTROPIC LIFT CONTINUES TO SUPPORT A PERSISTENT CLUSTER OF
SHOWERS OVER SCNTRL UPPER MI INTO EARLY AFTERNOON. UPSTREAM A
VIGOROUS SHRTWV ROTATING OVER SD/NE WILL LIFT TOWARD THE UPPER GREAT
LAKES TONIGHT BRINGING SHRA TO UPPER MI MAINLY TONIGHT INTO EARLY
WED. AT THE SFC...A WEAK FRONTAL BOUNDARY EXTENDED FROM CNTRL IA
THROUGH CNTRAL WI INTO CNTRL LWR MI. WITH HIGH PRES OVER NRN
ONTARIO...LIGHT NE WINDS PREVAILED ACROSS THE NRN LAKES TODAY.
TONIGHT...ATTENTION TURNS TO THE DEVELOPING UNSEASONABLY STRONG LOW
PRES SYSTEM MOVING OUT OF THE PLAINS. THE SD/NE SHRTWV WILL SUPPORT
A DEEPENING LOW MOVING INTO SRN MN BY 00Z/WED AND THEN INTO NRN
WI/SW U.P. BY 12Z/WED AS THE CENTRAL PRESSURE LOWERS NEAR 995 MB
APPROACHING RECORD LEVELS FOR THIS TIME OF YEAR. STRONG MOISTURE
TRANSPORT AND 305K-310K ISENTROPIC ASCENT WILL BRING AN AREA OF RAIN
THROUGH UPPER MI TONIGHT...MAINLY AFTER MIDNIGHT. HOWEVER...THIS
TRANSIENT BAND IS EXPECTED TO BRING QPF AMOUNTS OF ONLY 0.25-0.40
INCHES OVER THE CNTRL AND ERN CWA. THE FAR WEST HAS THE POTENTIAL TO
GET HIGHER AMOUNTS (0.5 TO ONE INCH) CLOSER TO THE STRONGEST DEEP
LAYER QVECTOR CONV AND LIFT WHICH WILL REMAIN TO THE WEST OVER NRN MN
AND WRN LAKE SUPERIOR. WITH MODEST MUCAPE VALUES INTO THE 200- 500
J/KG RANGE ONLY ISOLD TSRA ARE EXPECTED.
WEDNESDAY...SHOWERS WILL BE EXITING N AND E WED MORNING AHEAD OF THE
COLD FRONT AND THEN THE DRY SLOT WITH THE SYSTEM WILL MOVE IN FROM
THE SW WED LATE MORNING/AFTERNOON. ALTHOUGH THERE WILL BE STRONG 0-6
KM SHEAR ALONG THE FRONTAL BOUNDARY...AMOUNT OF INSTABILITY (MODELS
PROJECT 300-600 J/KG) REMAINS IN QUESTION AS THERE COULD BE
CONSIDERABLE CLOUD COVER LINGERING OVER THE AREA. BUT IF SUFFICIENT
INSTABILITY DEVELOPS AHEAD/ALONG THE FRONT...THERE COULD BE SOME
STRONG TO POSSIBLY SEVERE STORMS FORMING OVER MAINLY THE CENTRAL AND
ERN CWA IN THE MORNING. AFTER THE DRY SLOT MOVES INTO MAINLY THE
CENTRAL AND ERN CWA EXPECT SHRA TO GENERALLY DISSIPATE IN THE
AFTERNOON. WRAP AROUND PRECIP/MOISTURE WITH SYSTEM COULD MOVE INTO
WRN UPPER MI LATE IN THE DAY. WED LOOKS WINDY OVER CENTRAL AND ERN
UPPER MI WITH S-SW WINDS GUSTING TO 25-30 MPH.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 251 PM EDT TUE AUG 18 2015
THE ANOMALOUS UPPER TROUGH AND SURFACE LOW (AROUND 3-4 SIGMA) WILL
BE CENTERED BETWEEN DULUTH AND ISLE ROYALE AT THE START OF THE LONG
TERM FORECAST. THESE FEATURES WILL BE SLOWLY LIFTING TO THE
NORTHEAST THROUGH THURSDAY...BRINGING THE POTENTIAL FOR RAIN
SHOWERS AND BREEZY CONDITIONS TO THE AREA DURING THAT PERIOD.
STARTING OFF THE PERIOD...THE MID LEVEL DRY SLOT WILL BE OVER THE
CENTRAL AND EASTERN U.P. AND DON/T EXPECT MUCH MORE THAN LOW CLOUDS
FOR THE EVENING. BUT OVER THE WEST...WRAP AROUND MOISTURE WILL LEAD
TO SCATTERED/NUMEROUS SHOWERS WILL BE OCCURRING AND WILL LIKELY SEE
SOME ASSISTANCE FROM TERRAIN ENHANCEMENT WITH THE WEST-NORTHWEST
WINDS BEHIND THE SURFACE TROUGH THAT WILL BE LOCATED OVER THE
CENTRAL U.P. AT 06Z THURSDAY. AS THAT LOW LIFTS TO THE NORTHEAST
OVERNIGHT WEDNESDAY INTO THURSDAY...EXPECT THE SHOWERS TO SHIFT
EASTWARD BEHIND THE TROUGH AND MOVE OVER THE CENTRAL/EASTERN U.P.
ACCUMULATIONS WILL BE LIGHTER THAN OVER THE WEST WITH LESS TERRAIN
INFLUENCE...BUT SHOULD STILL SEE A FEW HUNDREDTHS BY LATE THURSDAY
AFTERNOON. WITH THE UPPER LOW QUICKLY MOVING TO THE NORTH THURSDAY
AFTERNOON INTO THURSDAY NIGHT...SHOULD SEE THE SHOWER COVERAGE
QUICKLY DIMINISH AS DRIER AIR ASSOCIATED WITH A SURFACE RIDGE MOVING
NORTHEAST INTO THE AREA. HAVE FOLLOWED THAT IDEA BOTH WITH THE POPS
AND CLOUD COVER THURSDAY AFTERNOON AND EVENING. IN FACT...SOME OF
THE AREAS NEAR THE WISCONSIN BORDER MAY HAVE THE LOW CLOUDS SCATTER
OUT BY EARLY AFTERNOON. IN ADDITION TO THE RAIN...EXPECT WINDS TO
INCREASE OVER AT LEAST THE WESTERN HALF OF THE CWA ON WEDNESDAY
NIGHT. THE DIFFERENCES IN THE MODELS LEADS TO SOME UNCERTAINTY IN
THE STRENGTH...BUT IT STILL APPEARS THAT GUSTS UP TO 30KTS ARE
POSSIBLE OVER THE KEWEENAW. FOR THE REST OF THE AREA...EXPECT GUSTS
IN THE 20-25KT RANGE ON THURSDAY.
THE HIGH PRESSURE RIDGE WILL BE NEAR THE AREA (FROM A HIGH IN THE
OHIO RIVER VALLEY) THROUGH FRIDAY NIGHT...BUT EXPECT THE GRADIENT
TO TIGHTEN THROUGH THAT PERIOD AS ANOTHER LOW DEVELOPS IN THE
NORTHERN PLAINS. THAT GRADIENT AND PLENTY OF SUNSHINE SHOULD LEAD TO
DECENT MIXING ON FRIDAY (AROUND 800MB)...RAISING TEMPERATURES TO
NORMAL OR SLIGHTLY ABOVE NORMAL VALUES UNDER OCCASIONALLY GUSTY
SOUTHWESTERLY WINDS (17-23KTS). WITH THE UPPER TROUGH AND SURFACE
LOW STILL NEAR THE NORTHERN PLAINS AND MOVING INTO THE UPPER
MISSISSIPPI VALLEY...EXPECT A SIMILAR DAY ON SATURDAY. HAVE REMOVED
THE POPS OVER THE WEST FOR SATURDAY AND WILL KEEP SKIES MOSTLY
SUNNY. SINCE THE TIGHTENING GRADIENT WILL REMAIN IN PLACE AHEAD OF
THE LOW...EXPECT WINDS TO BE A LITTLE GUSTIER THAN FRIDAY (UP TO
25KTS) AND TEMPERATURES TO BE A FEW DEGREES WARMER.
THE UPPER TROUGH FOR THE SECOND HALF OF THE WEEKEND
WILL MOVE THROUGH THE UPPER GREAT LAKES REGION OVERNIGHT SATURDAY
THROUGH SUNDAY EVENING. MEANWHILE...THE SURFACE LOW WILL LIFT
NORTH-NORTHEAST FROM NORTHWEST MINNESOTA TO FAR NORTHERN ONTARIO.
THIS WILL LEAD TO A SHARP COLD FRONT MOVING EAST ACROSS THE AREA ON
SUNDAY. MODELS SEEM TO BE FOCUSING ON LATE SATURDAY NIGHT AND
SUNDAY MORNING FOR THE FRONT TO MOVE THROUGH AND WILL FOCUS THE
HIGHEST POPS DURING THAT PERIOD (LOW LIKELY) AND QUICKLY RAMP
UP/DOWN ON BOTH SIDES. MODELS NOT SHOWING A WHOLE LOT OF INSTABILITY
AHEAD OF THE FRONT (MUCAPE VALUES ONLY UP TO 500 J/KG)...SO THINK
THAT THE THUNDER THREAT WILL BE LIMITED AND WILL CAP AT CHANCES.
THE COLD FRONT WILL USHER IN ANOTHER PERIOD OF BELOW NORMAL
TEMPERATURES FOR THE START OF NEXT WEEK AS HIGH PRESSURE BUILDS
OVER THE AREA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 253 PM EDT TUE AUG 18 2015
MAINLY MVFR CIGS ARE EXPECTED AT KSAW AND KCMX WITH CONTINUED MOIST
UPSLOPE E-NE FLOW THIS AFTERNOON. CIGS SHOULD ALSO LOWER AT IWD
TOWARD EVENING AS A STRENGTHENING ESE FLOW AHEAD OF DEEPENING LOW
PRES IN THE PLAINS WL BRING A RETURN OF MORE WDSPRD -RA/MVFR
CONDITIONS IN THE EVENING DROPPING TO IFR/LIFR OVERNIGHT. EXPECT
SLOWLY IMPROVING CONDITIONS BY LATE WED MORNING IN THE WAKE OF THE
FRONT ALONG WITH GUSTY SW WINDS NEAR 25 KTS AT KSAW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 327 PM EDT TUE AUG 18 2015
AS LOW PRES ORGANIZES AND STRENGTHENS OVER THE PLAINS THIS EVENING
...NE WINDS WILL BEGIN TO INCREASE...ESPECIALLY OVER WRN LAKE
SUPERIOR WHERE GUSTS SHOULD REACH 30KT LATE AFTN/EARLY EVENING. MAY
EVEN BE A FEW GALE GUSTS NEAR APOSTLE ISLANDS EARLY EVENING. THIS
LOW WILL BECOME UNSEASONABLY DEEP FOR AUG AS IT LIFTS ACROSS WRN
LAKE SUPERIOR WED AFTERNOON. 20-30KT WINDS ARE EXPECTED OVER MUCH OF
THE LAKE TONIGHT INTO WED. MAY SEE GALE FORCE GUSTS OVER FAR WRN
LAKE SUPERIOR IN THE NE WINDS AHEAD OF THE LOW TONIGHT AND THEN IN
THE WESTERLY WINDS ACROSS WRN AND CENTRAL LAKE SUPERIOR ON THU AS
THE LOW LIFTS N OF THE AREA. WINDS WILL DIMINISH TO UNDER 20KT BY
FRI...AND THEN BEGIN TO INCREASE SOME AGAIN ON SAT AHEAD OF THE NEXT
COLD FRONT MOVING OUT ACROSS THE PLAINS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...SRF
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
328 PM EDT TUE AUG 18 2015
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 327 PM EDT TUE AUG 18 2015
WV IMAGERY AND RAP ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM NRN HUDSON BAY INTO THE NRN PLAINS RESULTING IN A WSW FLOW INTO
THE NRN GREAT LAKES. A LINGERNIG AREA OF 700 MB FGEN AND WEAK
WAA/ISENTROPIC LIFT CONTINUES TO SUPPORT A PERSISTENT CLUSTER OF
SHOWERS OVER SCNTRL UPPER MI INTO EARLY AFTERNOON. UPSTREAM A
VIGOROUS SHRTWV ROTATING OVER SD/NE WILL LIFT TOWARD THE UPPER GREAT
LAKES TONIGHT BRINGING SHRA TO UPPER MI MAINLY TONIGHT INTO EARLY
WED. AT THE SFC...A WEAK FRONTAL BOUNDARY EXTENDED FROM CNTRL IA
THROUGH CNTRAL WI INTO CNTRL LWR MI. WITH HIGH PRES OVER NRN
ONTARIO...LIGHT NE WINDS PREVAILED ACROSS THE NRN LAKES TODAY.
TONIGHT...ATTENTION TURNS TO THE DEVELOPING UNSEASONABLY STRONG LOW
PRES SYSTEM MOVING OUT OF THE PLAINS. THE SD/NE SHRTWV WILL SUPPORT
A DEEPENING LOW MOVING INTO SRN MN BY 00Z/WED AND THEN INTO NRN
WI/SW U.P. BY 12Z/WED AS THE CENTRAL PRESSURE LOWERS NEAR 995/996 MB
APPROACHING RECORD LEVELS FOR THIS TIME OF YEAR. STRONG MOISTURE
TRANSPORT AND 305K-310K ISENTROPIC ASCENT WILL BRING AN AREA OF RAIN
THROUGH UPPER MI TONIGHT...MAINLY AFTER MIDNIGHT. HOWEVER...THIS
TRANSIENT BAND IS EXPECTED TO BRING QPF AMOUNTS OF ONLY 0.25-0.40
INCHES OVER THE CNTRL AND ERN CWA. THE FAR WEST HAS THE POTENTIAL TO
GET HIGHER AMOUNTS (0.5 TO ONE INCH) CLOSER TO THE STRONGEST DEEP
LAYER QVECTOR CONV AND LIFT WHICH WILL REMAIN TO THE WEST OVER NRN
MN AND WRN LAKE SUPERIOR. WITH MODEST MUCAPE VALUES INTO THE 200-
500 J/KG RANGE ONLY ISOLD TSRA ARE EXPECTED.
WEDNESDAY...SHOWERS WILL BE EXITING N AND E WED MORNING AHEAD OF THE
COLD FRONT AND THEN THE DRY SLOT WITH THE SYSTEM WILL MOVE IN FROM
THE SW WED LATE MORNING/AFTERNOON. ALTHOUGH THERE WILL BE STRONG 0-6
KM SHEAR ALONG THE FRONTAL BOUNDARY...HOWEVER AMOUNT OF INSTABILITY
(MODELS PROJECT 300-600 J/KG) REMAINS IN QUESTION AS THERE COULD BE
CONSIDERABLE CLOUD COVER LINGERING OVER THE AREA. BUT IF SUFFICIENT
INSTABILITY DEVELOPS AHEAD/ALONG THE FRONT...THERE COULD BE SOME
STRONG TO POSSIBLY SEVERE STORMS FORMING OVER MAINLY THE CENTRAL AND
ERN CWA IN THE MORNING. AFTER THE DRY SLOT MOVES INTO MAINLY THE
CENTRAL AND ERN CWA EXPECT SHRA TO GENERALLY DISSIPATE IN THE
AFTERNOON. WRAP AROUND PRECIP/MOISTURE WITH SYSTEM COULD MOVE INTO
WRN UPPER MI LATE IN THE DAY. WED LOOKS WINDY OVER CENTRAL AND ERN
UPPER MI WITH S-SW WINDS GUSTING TO 25-30 MPH.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 251 PM EDT TUE AUG 18 2015
THE ANOMALOUS UPPER TROUGH AND SURFACE LOW (AROUND 3-4 SIGMA) WILL
BE CENTERED BETWEEN DULUTH AND ISLE ROYALE AT THE START OF THE LONG
TERM FORECAST. THESE FEATURES WILL BE SLOWLY LIFTING TO THE
NORTHEAST THROUGH THURSDAY...BRINGING THE POTENTIAL FOR RAIN
SHOWERS AND BREEZY CONDITIONS TO THE AREA DURING THAT PERIOD.
STARTING OFF THE PERIOD...THE MID LEVEL DRY SLOT WILL BE OVER THE
CENTRAL AND EASTERN U.P. AND DON/T EXPECT MUCH MORE THAN LOW CLOUDS
FOR THE EVENING. BUT OVER THE WEST...WRAP AROUND MOISTURE WILL LEAD
TO SCATTERED/NUMEROUS SHOWERS WILL BE OCCURRING AND WILL LIKELY SEE
SOME ASSISTANCE FROM TERRAIN ENHANCEMENT WITH THE WEST-NORTHWEST
WINDS BEHIND THE SURFACE TROUGH THAT WILL BE LOCATED OVER THE
CENTRAL U.P. AT 06Z THURSDAY. AS THAT LOW LIFTS TO THE NORTHEAST
OVERNIGHT WEDNESDAY INTO THURSDAY...EXPECT THE SHOWERS TO SHIFT
EASTWARD BEHIND THE TROUGH AND MOVE OVER THE CENTRAL/EASTERN U.P.
ACCUMULATIONS WILL BE LIGHTER THAN OVER THE WEST WITH LESS TERRAIN
INFLUENCE...BUT SHOULD STILL SEE A FEW HUNDREDTHS BY LATE THURSDAY
AFTERNOON. WITH THE UPPER LOW QUICKLY MOVING TO THE NORTH THURSDAY
AFTERNOON INTO THURSDAY NIGHT...SHOULD SEE THE SHOWER COVERAGE
QUICKLY DIMINISH AS DRIER AIR ASSOCIATED WITH A SURFACE RIDGE MOVING
NORTHEAST INTO THE AREA. HAVE FOLLOWED THAT IDEA BOTH WITH THE POPS
AND CLOUD COVER THURSDAY AFTERNOON AND EVENING. IN FACT...SOME OF
THE AREAS NEAR THE WISCONSIN BORDER MAY HAVE THE LOW CLOUDS SCATTER
OUT BY EARLY AFTERNOON. IN ADDITION TO THE RAIN...EXPECT WINDS TO
INCREASE OVER AT LEAST THE WESTERN HALF OF THE CWA ON WEDNESDAY
NIGHT. THE DIFFERENCES IN THE MODELS LEADS TO SOME UNCERTAINTY IN
THE STRENGTH...BUT IT STILL APPEARS THAT GUSTS UP TO 30KTS ARE
POSSIBLE OVER THE KEWEENAW. FOR THE REST OF THE AREA...EXPECT GUSTS
IN THE 20-25KT RANGE ON THURSDAY.
THE HIGH PRESSURE RIDGE WILL BE NEAR THE AREA (FROM A HIGH IN THE
OHIO RIVER VALLEY) THROUGH FRIDAY NIGHT...BUT EXPECT THE GRADIENT
TO TIGHTEN THROUGH THAT PERIOD AS ANOTHER LOW DEVELOPS IN THE
NORTHERN PLAINS. THAT GRADIENT AND PLENTY OF SUNSHINE SHOULD LEAD TO
DECENT MIXING ON FRIDAY (AROUND 800MB)...RAISING TEMPERATURES TO
NORMAL OR SLIGHTLY ABOVE NORMAL VALUES UNDER OCCASIONALLY GUSTY
SOUTHWESTERLY WINDS (17-23KTS). WITH THE UPPER TROUGH AND SURFACE
LOW STILL NEAR THE NORTHERN PLAINS AND MOVING INTO THE UPPER
MISSISSIPPI VALLEY...EXPECT A SIMILAR DAY ON SATURDAY. HAVE REMOVED
THE POPS OVER THE WEST FOR SATURDAY AND WILL KEEP SKIES MOSTLY
SUNNY. SINCE THE TIGHTENING GRADIENT WILL REMAIN IN PLACE AHEAD OF
THE LOW...EXPECT WINDS TO BE A LITTLE GUSTIER THAN FRIDAY (UP TO
25KTS) AND TEMPERATURES TO BE A FEW DEGREES WARMER.
THE UPPER TROUGH FOR THE SECOND HALF OF THE WEEKEND
WILL MOVE THROUGH THE UPPER GREAT LAKES REGION OVERNIGHT SATURDAY
THROUGH SUNDAY EVENING. MEANWHILE...THE SURFACE LOW WILL LIFT
NORTH-NORTHEAST FROM NORTHWEST MINNESOTA TO FAR NORTHERN ONTARIO.
THIS WILL LEAD TO A SHARP COLD FRONT MOVING EAST ACROSS THE AREA ON
SUNDAY. MODELS SEEM TO BE FOCUSING ON LATE SATURDAY NIGHT AND
SUNDAY MORNING FOR THE FRONT TO MOVE THROUGH AND WILL FOCUS THE
HIGHEST POPS DURING THAT PERIOD (LOW LIKELY) AND QUICKLY RAMP
UP/DOWN ON BOTH SIDES. MODELS NOT SHOWING A WHOLE LOT OF INSTABILITY
AHEAD OF THE FRONT (MUCAPE VALUES ONLY UP TO 500 J/KG)...SO THINK
THAT THE THUNDER THREAT WILL BE LIMITED AND WILL CAP AT CHANCES.
THE COLD FRONT WILL USHER IN ANOTHER PERIOD OF BELOW NORMAL
TEMPERATURES FOR THE START OF NEXT WEEK AS HIGH PRESSURE BUILDS
OVER THE AREA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 253 PM EDT TUE AUG 18 2015
MAINLY MVFR CIGS ARE EXPECTED AT KSAW AND KCMX WITH CONTINUED MOIST
UPSLOPE E-NE FLOW THIS AFTERNOON. CIGS SHOULD ALSO LOWER AT IWD
TOWARD EVENING AS A STRENGTHENING ESE FLOW AHEAD OF DEEPENING LOW
PRES IN THE PLAINS WL BRING A RETURN OF MORE WDSPRD -RA/MVFR
CONDITIONS IN THE EVENING DROPPING TO IFR/LIFR OVERNIGHT. EXPECT
SLOWLY IMPROVING CONDITIONS BY LATE WED MORNING IN THE WAKE OF THE
FRONT ALONG WITH GUSTY SW WINDS NEAR 25 KTS AT KSAW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 327 PM EDT TUE AUG 18 2015
AS LOW PRES ORGANIZES AND STRENGTHENS OVER THE PLAINS THIS EVENING
...NE WINDS WILL BEGIN TO INCREASE...ESPECIALLY OVER WRN LAKE
SUPERIOR WHERE GUSTS SHOULD REACH 30KT LATE AFTN/EARLY EVENING. MAY
EVEN BE A FEW GALE GUSTS NEAR APOSTLE ISLANDS EARLY EVENING. THIS
LOW WILL BECOME UNSEASONABLY DEEP FOR AUG AS IT LIFTS ACROSS WRN
LAKE SUPERIOR WED AFTERNOON. 20-30KT WINDS ARE EXPECTED OVER MUCH OF
THE LAKE TONIGHT INTO WED. MAY SEE GALE FORCE GUSTS OVER FAR WRN
LAKE SUPERIOR IN THE NE WINDS AHEAD OF THE LOW TONIGHT AND THEN IN
THE WESTERLY WINDS ACROSS WRN AND CENTRAL LAKE SUPERIOR ON THU AS
THE LOW LIFTS N OF THE AREA. WINDS WILL DIMINISH TO UNDER 20KT BY
FRI...AND THEN BEGIN TO INCREASE SOME AGAIN ON SAT AHEAD OF THE NEXT
COLD FRONT MOVING OUT ACROSS THE PLAINS. &&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...SRF
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
257 PM EDT TUE AUG 18 2015
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 500 AM EDT TUE AUG 18 2015
WV IMAGERY AND RAP ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM NRN HUDSON BAY INTO THE NRN PLAINS RESULTING IN WNW FLOW
THROUGH THE NRN GREAT LAKES. A WEAK SHORTWAVE TROUGH AND AREA OF 850-
700 MB FGEN SUPPORTED A BAND OF SHOWERS OVER WRN UPPER MI. UPSTREAM
A VIGOROUS SHRTWV WAS MOVING THROUGH SD/NE. AT THE SFC...A WEAK
FRONTAL BOUNDARY EXTENDED FROM CNTRL LOWER MI THROUGH SE WI AND SW
IA TO LOW PRES OVER NRN KS. WITH HIGH PRES OVER NRN ONTARIO...LIGHT
NE WINDS PREVAILED ACROSS THE NRN LAKES.
EXPECT THE PCPN OVER THE WEST TO DIMINISH EARLY AS THE SHRTWV AND
FGEN LIFT MOVE OFF TO THE NORTHEAST. HOWEVER...SOME SCT -SHRA MAY
LINGER OVER THE SOUTH AS ANOTHER WEAK SHRTWV BRUSHES THE AREA TO THE
SE.
ATTENTION...WILL THEN TURN TO THE DEVELOPING AND UNSEASONABLY STRONG
LOW PRES SYSTEM MOVING OUT OF THE PLAINS. THE SD/NE SHRTWV WILL
SUPPORT A DEEPENING LOW MOVING INTO THE NW CORNER OF IA BY 00Z/WED
AND ERN MN BY 12Z/WED. THE MODELS HAVE TRENDED TOWARD A SLIGHTLY
SLOWER PROGRESSION OF THE LOW AS THE STRONG JET MOVING OUT OF THE
PLAINS HELPS CUT OFF THE MID LEVEL LOW. AN AREA OF STRONG MOISTURE
TRANSPORT AND 305K-310K ISENTROPIC ASCENT WILL BRING AN AREA OF RAIN
THROUGH UPPER MI TONIGHT...MAINLY AFTER MIDNIGHT. HOWEVER...THIS
TRANSIENT BAND IS EXPECTED TO BRING QPF AMOUNTS ONLY IN THE 0.25-
0.50 INCH RANGE OVER THE CNTRL AND ERN CWA. HIGHER AMOUNTS TO AROUND
AN INCH WILL BE POSSIBLE OVER THE FAR WEST CLOSER TO THE STRONGEST
DEEP LAYER QVECTOR CONV AND LIFT WHICH WILL REMAIN TO THE WEST OVER
NRN MN AND WRN LAKE SUPERIOR. WITH MODEST MUCAPE VALUES INTO THE 200-
400 J/KG RANGE ONLY ISOLD TSRA ARE EXPECTED.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 251 PM EDT TUE AUG 18 2015
THE ANOMALOUS UPPER TROUGH AND SURFACE LOW (AROUND 3-4 SIGMA) WILL
BE CENTERED BETWEEN DULUTH AND ISLE ROYALE AT THE START OF THE LONG
TERM FORECAST. THESE FEATURES WILL BE SLOWLY LIFTING TO THE
NORTHEAST THROUGH THURSDAY...BRINGING THE POTENTIAL FOR RAIN
SHOWERS AND BREEZY CONDITIONS TO THE AREA DURING THAT PERIOD.
STARTING OFF THE PERIOD...THE MID LEVEL DRY SLOT WILL BE OVER THE
CENTRAL AND EASTERN U.P. AND DON/T EXPECT MUCH MORE THAN LOW CLOUDS
FOR THE EVENING. BUT OVER THE WEST...WRAP AROUND MOISTURE WILL LEAD
TO SCATTERED/NUMEROUS SHOWERS WILL BE OCCURRING AND WILL LIKELY SEE
SOME ASSISTANCE FROM TERRAIN ENHANCEMENT WITH THE WEST-NORTHWEST
WINDS BEHIND THE SURFACE TROUGH THAT WILL BE LOCATED OVER THE
CENTRAL U.P. AT 06Z THURSDAY. AS THAT LOW LIFTS TO THE NORTHEAST
OVERNIGHT WEDNESDAY INTO THURSDAY...EXPECT THE SHOWERS TO SHIFT
EASTWARD BEHIND THE TROUGH AND MOVE OVER THE CENTRAL/EASTERN U.P.
ACCUMULATIONS WILL BE LIGHTER THAN OVER THE WEST WITH LESS TERRAIN
INFLUENCE...BUT SHOULD STILL SEE A FEW HUNDREDTHS BY LATE THURSDAY
AFTERNOON. WITH THE UPPER LOW QUICKLY MOVING TO THE NORTH THURSDAY
AFTERNOON INTO THURSDAY NIGHT...SHOULD SEE THE SHOWER COVERAGE
QUICKLY DIMINISH AS DRIER AIR ASSOCIATED WITH A SURFACE RIDGE MOVING
NORTHEAST INTO THE AREA. HAVE FOLLOWED THAT IDEA BOTH WITH THE POPS
AND CLOUD COVER THURSDAY AFTERNOON AND EVENING. IN FACT...SOME OF
THE AREAS NEAR THE WISCONSIN BORDER MAY HAVE THE LOW CLOUDS SCATTER
OUT BY EARLY AFTERNOON. IN ADDITION TO THE RAIN...EXPECT WINDS TO
INCREASE OVER AT LEAST THE WESTERN HALF OF THE CWA ON WEDNESDAY
NIGHT. THE DIFFERENCES IN THE MODELS LEADS TO SOME UNCERTAINTY IN
THE STRENGTH...BUT IT STILL APPEARS THAT GUSTS UP TO 30KTS ARE
POSSIBLE OVER THE KEWEENAW. FOR THE REST OF THE AREA...EXPECT GUSTS
IN THE 20-25KT RANGE ON THURSDAY.
THE HIGH PRESSURE RIDGE WILL BE NEAR THE AREA (FROM A HIGH IN THE
OHIO RIVER VALLEY) THROUGH FRIDAY NIGHT...BUT EXPECT THE GRADIENT
TO TIGHTEN THROUGH THAT PERIOD AS ANOTHER LOW DEVELOPS IN THE
NORTHERN PLAINS. THAT GRADIENT AND PLENTY OF SUNSHINE SHOULD LEAD TO
DECENT MIXING ON FRIDAY (AROUND 800MB)...RAISING TEMPERATURES TO
NORMAL OR SLIGHTLY ABOVE NORMAL VALUES UNDER OCCASIONALLY GUSTY
SOUTHWESTERLY WINDS (17-23KTS). WITH THE UPPER TROUGH AND SURFACE
LOW STILL NEAR THE NORTHERN PLAINS AND MOVING INTO THE UPPER
MISSISSIPPI VALLEY...EXPECT A SIMILAR DAY ON SATURDAY. HAVE REMOVED
THE POPS OVER THE WEST FOR SATURDAY AND WILL KEEP SKIES MOSTLY
SUNNY. SINCE THE TIGHTENING GRADIENT WILL REMAIN IN PLACE AHEAD OF
THE LOW...EXPECT WINDS TO BE A LITTLE GUSTIER THAN FRIDAY (UP TO
25KTS) AND TEMPERATURES TO BE A FEW DEGREES WARMER.
THE UPPER TROUGH FOR THE SECOND HALF OF THE WEEKEND
WILL MOVE THROUGH THE UPPER GREAT LAKES REGION OVERNIGHT SATURDAY
THROUGH SUNDAY EVENING. MEANWHILE...THE SURFACE LOW WILL LIFT
NORTH-NORTHEAST FROM NORTHWEST MINNESOTA TO FAR NORTHERN ONTARIO.
THIS WILL LEAD TO A SHARP COLD FRONT MOVING EAST ACROSS THE AREA ON
SUNDAY. MODELS SEEM TO BE FOCUSING ON LATE SATURDAY NIGHT AND
SUNDAY MORNING FOR THE FRONT TO MOVE THROUGH AND WILL FOCUS THE
HIGHEST POPS DURING THAT PERIOD (LOW LIKELY) AND QUICKLY RAMP
UP/DOWN ON BOTH SIDES. MODELS NOT SHOWING A WHOLE LOT OF INSTABILITY
AHEAD OF THE FRONT (MUCAPE VALUES ONLY UP TO 500 J/KG)...SO THINK
THAT THE THUNDER THREAT WILL BE LIMITED AND WILL CAP AT CHANCES.
THE COLD FRONT WILL USHER IN ANOTHER PERIOD OF BELOW NORMAL
TEMPERATURES FOR THE START OF NEXT WEEK AS HIGH PRESSURE BUILDS
OVER THE AREA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 253 PM EDT TUE AUG 18 2015
MAINLY MVFR CIGS ARE EXPECTED AT KSAW AND KCMX WITH CONTINUED MOIST
UPSLOPE E-NE FLOW THIS AFTERNOON. CIGS SHOULD ALSO LOWER AT IWD
TOWARD EVENING AS A STRENGTHENING ESE FLOW AHEAD OF DEEPENING LOW
PRES IN THE PLAINS WL BRING A RETURN OF MORE WDSPRD -RA/MVFR
CONDITIONS IN THE EVENING DROPPING TO IFR/LIFR OVERNIGHT. EXPECT
SLOWLY IMPROVING CONDITIONS BY LATE WED MORNING IN THE WAKE OF THE
FRONT ALONG WITH GUSTY SW WINDS NEAR 25 KTS AT KSAW. &&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 514 AM EDT TUE AUG 18 2015
HIGH PRES STRETCHING FROM SOUTHERN MANITOBA THROUGH JAMES BAY WILL
EXTEND A RIDGE INTO THE UPPER LAKES THROUGH THIS MORNING...RESULTING
IN LIGHT WINDS UNDER 15KT ACROSS LAKE SUPERIOR. THEN...AS LOW PRES
ORGANIZES AND STRENGTHENS OVER THE PLAINS TUE...NE WINDS WILL BEGIN
TO INCREASE...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE GUSTS SHOULD
REACH 25-30KT LATE AFTN/EARLY EVENING. THIS LOW WILL BECOME
UNSEASONABLY DEEP FOR AUG AS IT LIFTS ACROSS FAR WRN LAKE SUPERIOR
WED AFTERNOON. 20-30KT WINDS ARE EXPECTED OVER MUCH OF THE LAKE
TONIGHT INTO WED. MAY SEE GALE FORCE GUSTS OVER FAR WRN LAKE SUPERIOR
IN THE NE WINDS AHEAD OF THE LOW TONIGHT AND THEN IN THE WESTERLY
WINDS ACROSS MAINLY CENTRAL LAKE SUPERIOR ON THU AS THE LOW LIFTS N
OF THE AREA. WINDS WILL DIMINISH TO UNDER 20KT FRI...AND THEN BEGIN
TO INCREASE AGAIN ON SAT AHEAD OF THE NEXT COLD FRONT MOVING OUT
ACROSS THE PLAINS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...VOSS
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
253 PM EDT TUE AUG 18 2015
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 500 AM EDT TUE AUG 18 2015
WV IMAGERY AND RAP ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM NRN HUDSON BAY INTO THE NRN PLAINS RESULTING IN WNW FLOW
THROUGH THE NRN GREAT LAKES. A WEAK SHORTWAVE TROUGH AND AREA OF 850-
700 MB FGEN SUPPORTED A BAND OF SHOWERS OVER WRN UPPER MI. UPSTREAM
A VIGOROUS SHRTWV WAS MOVING THROUGH SD/NE. AT THE SFC...A WEAK
FRONTAL BOUNDARY EXTENDED FROM CNTRL LOWER MI THROUGH SE WI AND SW
IA TO LOW PRES OVER NRN KS. WITH HIGH PRES OVER NRN ONTARIO...LIGHT
NE WINDS PREVAILED ACROSS THE NRN LAKES.
EXPECT THE PCPN OVER THE WEST TO DIMINISH EARLY AS THE SHRTWV AND
FGEN LIFT MOVE OFF TO THE NORTHEAST. HOWEVER...SOME SCT -SHRA MAY
LINGER OVER THE SOUTH AS ANOTHER WEAK SHRTWV BRUSHES THE AREA TO THE
SE.
ATTENTION...WILL THEN TURN TO THE DEVELOPING AND UNSEASONABLY STRONG
LOW PRES SYSTEM MOVING OUT OF THE PLAINS. THE SD/NE SHRTWV WILL
SUPPORT A DEEPENING LOW MOVING INTO THE NW CORNER OF IA BY 00Z/WED
AND ERN MN BY 12Z/WED. THE MODELS HAVE TRENDED TOWARD A SLIGHTLY
SLOWER PROGRESSION OF THE LOW AS THE STRONG JET MOVING OUT OF THE
PLAINS HELPS CUT OFF THE MID LEVEL LOW. AN AREA OF STRONG MOISTURE
TRANSPORT AND 305K-310K ISENTROPIC ASCENT WILL BRING AN AREA OF RAIN
THROUGH UPPER MI TONIGHT...MAINLY AFTER MIDNIGHT. HOWEVER...THIS
TRANSIENT BAND IS EXPECTED TO BRING QPF AMOUNTS ONLY IN THE 0.25-
0.50 INCH RANGE OVER THE CNTRL AND ERN CWA. HIGHER AMOUNTS TO AROUND
AN INCH WILL BE POSSIBLE OVER THE FAR WEST CLOSER TO THE STRONGEST
DEEP LAYER QVECTOR CONV AND LIFT WHICH WILL REMAIN TO THE WEST OVER
NRN MN AND WRN LAKE SUPERIOR. WITH MODEST MUCAPE VALUES INTO THE 200-
400 J/KG RANGE ONLY ISOLD TSRA ARE EXPECTED.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 251 PM EDT TUE AUG 18 2015
THE ANOMALOUS UPPER TROUGH AND SURFACE LOW (AROUND 3-4 SIGMA) WILL
BE CENTERED BETWEEN DULUTH AND ISLE ROYALE AT THE START OF THE LONG
TERM FORECAST. THESE FEATURES WILL BE SLOWLY LIFTING TO THE
NORTHEAST THROUGH THURSDAY...BRINGING THE POTENTIAL FOR RAIN
SHOWERS AND BREEZY CONDITIONS TO THE AREA DURING THAT PERIOD.
STARTING OFF THE PERIOD...THE MID LEVEL DRY SLOT WILL BE OVER THE
CENTRAL AND EASTERN U.P. AND DON/T EXPECT MUCH MORE THAN LOW CLOUDS
FOR THE EVENING. BUT OVER THE WEST...WRAP AROUND MOISTURE WILL LEAD
TO SCATTERED/NUMEROUS SHOWERS WILL BE OCCURRING AND WILL LIKELY SEE
SOME ASSISTANCE FROM TERRAIN ENHANCEMENT WITH THE WEST-NORTHWEST
WINDS BEHIND THE SURFACE TROUGH THAT WILL BE LOCATED OVER THE
CENTRAL U.P. AT 06Z THURSDAY. AS THAT LOW LIFTS TO THE NORTHEAST
OVERNIGHT WEDNESDAY INTO THURSDAY...EXPECT THE SHOWERS TO SHIFT
EASTWARD BEHIND THE TROUGH AND MOVE OVER THE CENTRAL/EASTERN U.P.
ACCUMULATIONS WILL BE LIGHTER THAN OVER THE WEST WITH LESS TERRAIN
INFLUENCE...BUT SHOULD STILL SEE A FEW HUNDREDTHS BY LATE THURSDAY
AFTERNOON. WITH THE UPPER LOW QUICKLY MOVING TO THE NORTH THURSDAY
AFTERNOON INTO THURSDAY NIGHT...SHOULD SEE THE SHOWER COVERAGE
QUICKLY DIMINISH AS DRIER AIR ASSOCIATED WITH A SURFACE RIDGE MOVING
NORTHEAST INTO THE AREA. HAVE FOLLOWED THAT IDEA BOTH WITH THE POPS
AND CLOUD COVER THURSDAY AFTERNOON AND EVENING. IN FACT...SOME OF
THE AREAS NEAR THE WISCONSIN BORDER MAY HAVE THE LOW CLOUDS SCATTER
OUT BY EARLY AFTERNOON. IN ADDITION TO THE RAIN...EXPECT WINDS TO
INCREASE OVER AT LEAST THE WESTERN HALF OF THE CWA ON WEDNESDAY
NIGHT. THE DIFFERENCES IN THE MODELS LEADS TO SOME UNCERTAINTY IN
THE STRENGTH...BUT IT STILL APPEARS THAT GUSTS UP TO 30KTS ARE
POSSIBLE OVER THE KEWEENAW. FOR THE REST OF THE AREA...EXPECT GUSTS
IN THE 20-25KT RANGE ON THURSDAY.
THE HIGH PRESSURE RIDGE WILL BE NEAR THE AREA (FROM A HIGH IN THE
OHIO RIVER VALLEY) THROUGH FRIDAY NIGHT...BUT EXPECT THE GRADIENT
TO TIGHTEN THROUGH THAT PERIOD AS ANOTHER LOW DEVELOPS IN THE
NORTHERN PLAINS. THAT GRADIENT AND PLENTY OF SUNSHINE SHOULD LEAD TO
DECENT MIXING ON FRIDAY (AROUND 800MB)...RAISING TEMPERATURES TO
NORMAL OR SLIGHTLY ABOVE NORMAL VALUES UNDER OCCASIONALLY GUSTY
SOUTHWESTERLY WINDS (17-23KTS). WITH THE UPPER TROUGH AND SURFACE
LOW STILL NEAR THE NORTHERN PLAINS AND MOVING INTO THE UPPER
MISSISSIPPI VALLEY...EXPECT A SIMILAR DAY ON SATURDAY. HAVE REMOVED
THE POPS OVER THE WEST FOR SATURDAY AND WILL KEEP SKIES MOSTLY
SUNNY. SINCE THE TIGHTENING GRADIENT WILL REMAIN IN PLACE AHEAD OF
THE LOW...EXPECT WINDS TO BE A LITTLE GUSTIER THAN FRIDAY (UP TO
25KTS) AND TEMPERATURES TO BE A FEW DEGREES WARMER.
THE UPPER TROUGH FOR THE SECOND HALF OF THE WEEKEND
WILL MOVE THROUGH THE UPPER GREAT LAKES REGION OVERNIGHT SATURDAY
THROUGH SUNDAY EVENING. MEANWHILE...THE SURFACE LOW WILL LIFT
NORTH-NORTHEAST FROM NORTHWEST MINNESOTA TO FAR NORTHERN ONTARIO.
THIS WILL LEAD TO A SHARP COLD FRONT MOVING EAST ACROSS THE AREA ON
SUNDAY. MODELS SEEM TO BE FOCUSING ON LATE SATURDAY NIGHT AND
SUNDAY MORNING FOR THE FRONT TO MOVE THROUGH AND WILL FOCUS THE
HIGHEST POPS DURING THAT PERIOD (LOW LIKELY) AND QUICKLY RAMP
UP/DOWN ON BOTH SIDES. MODELS NOT SHOWING A WHOLE LOT OF INSTABILITY
AHEAD OF THE FRONT (MUCAPE VALUES ONLY UP TO 500 J/KG)...SO THINK
THAT THE THUNDER THREAT WILL BE LIMITED AND WILL CAP AT CHANCES.
THE COLD FRONT WILL USHER IN ANOTHER PERIOD OF BELOW NORMAL
TEMPERATURES FOR THE START OF NEXT WEEK AS HIGH PRESSURE BUILDS
OVER THE AREA.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 742 AM EDT TUE AUG 18 2015
MAINLY MVFR CIGS ARE EXPECTED AT SAW WITH CONTINUED MOIST UPSLOPE NE
FLOW TODAY. CIGS SHOULD ALSO LOWER AT IWD AND CMX BUT WITH DRIER AIR
IN PLACE...EXPECT CONDITIONS TO REMAIN VFR UNTIL LATER THIS
AFTERNOON. A STRENGTHENING ESE FLOW AHEAD OF DEEPENING LO PRES IN
THE PLAINS WL BRING A RETURN OF MORE WDSPRD -RA/MVFR CONDITIONS IN
THE EVENING DROPPING TO IFR OVERNIGHT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 514 AM EDT TUE AUG 18 2015
HIGH PRES STRETCHING FROM SOUTHERN MANITOBA THROUGH JAMES BAY WILL
EXTEND A RIDGE INTO THE UPPER LAKES THROUGH THIS MORNING...RESULTING
IN LIGHT WINDS UNDER 15KT ACROSS LAKE SUPERIOR. THEN...AS LOW PRES
ORGANIZES AND STRENGTHENS OVER THE PLAINS TUE...NE WINDS WILL BEGIN
TO INCREASE...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE GUSTS SHOULD
REACH 25-30KT LATE AFTN/EARLY EVENING. THIS LOW WILL BECOME
UNSEASONABLY DEEP FOR AUG AS IT LIFTS ACROSS FAR WRN LAKE SUPERIOR
WED AFTERNOON. 20-30KT WINDS ARE EXPECTED OVER MUCH OF THE LAKE
TONIGHT INTO WED. MAY SEE GALE FORCE GUSTS OVER FAR WRN LAKE SUPERIOR
IN THE NE WINDS AHEAD OF THE LOW TONIGHT AND THEN IN THE WESTERLY
WINDS ACROSS MAINLY CENTRAL LAKE SUPERIOR ON THU AS THE LOW LIFTS N
OF THE AREA. WINDS WILL DIMINISH TO UNDER 20KT FRI...AND THEN BEGIN
TO INCREASE AGAIN ON SAT AHEAD OF THE NEXT COLD FRONT MOVING OUT
ACROSS THE PLAINS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS GAYLORD MI
113 PM EDT TUE AUG 18 2015
.UPDATE...
ISSUED AT 1033 AM EDT TUE AUG 18 2015
SCT/NMRS SHOWERS CONTINUE TO DEVELOP ACROSS MUCH OF THE WRN GREAT
LAKES LATE THIS MORNING...INCLUDING OUR CWA WHERE SOME BRIEF ISOLD
THUNDER HAS ALSO DEVELOPED PER RECENT LIGHTNING DATA. FORCING
REMAINS WEAK...WITH LITTLE IN THE WAY TO ORGANIZE ANY OF THE
CONVECTION. WARM FRONT IS TRYING TO PUSH NORTHWARD INTO SRN
SECTIONS OF OUR CWA...BUT IS MAKING LITTLE PROGRESS GIVEN THICK
CLOUD COVER AND PRECIP ACROSS OUR AREA. CLOUDS AND PRECIP ARE ALSO
GREATLY LIMITING THE POTENTIAL FOR INCREASED INSTABILITY AS THE
DAY SLOWLY HEATS UP. ALL OF THE ABOVE WILL REMAIN IN PLACE THRU
THE AFTERNOON...WHICH WILL CONTINUE TO LIMIT OUR THUNDER CHANCES.
HOWEVER...DO STILL EXPECT PRECIP ITSELF WILL GRADUALLY EXPAND
THANKS TO SOME DIURNALLY-ENHANCED INSTABILITY AND AMPLE MOISTURE
POOLING ALONG AND NORTH OF THE WARM FRONT. HAVE MADE ONLY MINOR
ADJUSTMENTS TO WX/POP FORECAST FOR THE AFTERNOON. OVERALL...EXPECT
A MAINLY CLOUDY AFTERNOON WITH WAVES OF SHOWERS AND POSSIBLY A FEW
THUNDERSTORMS...WITH THE HIGHEST POPS ACROSS NRN LWR MICHIGAN.
&&
.NEAR TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 328 AM EDT TUE AUG 18 2015
HIGH IMPACT WEATHER POTENTIAL...NON-SEVERE THUNDERSTORMS TODAY AND
TONIGHT.
DIFFUSE COLD FRONT RESTS ROUGHLY FROM OSC TO MBL. THIS FRONT IS
STALLING OUT...AS LEE CYCLOGENESIS GETS UNDERWAY IN THE CENTRAL
HIGH PLAINS. SOME SHRA ARE SEEN OVER CENTRAL/NORTHERN LAKE MI AND
SURROUNDING AREAS. A FEW SHRA HAVE ALSO RECENTLY DEVELOPED JUST SW
OF LAN. NO THUNDER LEFT IN OUR NECK OF THE WOODS. THE FRONT WILL
WOBBLE ACROSS CENTRAL/NORTHERN LOWER MI OVER THE NEXT 24
HOURS...AS HEATING/CONVECTION/SOUTHERLY FLOW WAXES AND WANES.
PRECIP TRENDS ARE THE MAIN CONCERN.
TODAY...A POTENT SHORTWAVE WILL DIG FROM THE NORTHERN TO CENTRAL
HIGH PLAINS TODAY. IN RESPONSE...PRESSURES WILL RAPIDLY FALL IN THE
CENTRAL PLAINS. BY MID-EVENING...A SUB-1000MB LOW WILL BE MOVING
INTO NW IOWA. SOUTHERLY 1000-850MB FLOW INTO LOWER MI WILL INCREASE
TO SOME DEGREE...THOUGH THE TIGHTEST PRESSURE GRADIENT WILL REMAIN
TO OUR WEST THRU 00Z. STILL...THAT AND DIURNAL HEATING/MIXING WILL
TEND TO PUSH THE FRONT NORTH. HOWEVER...PRECIP AND SUBSEQUENT COLD-
POOL GENERATION NORTH OF THE FRONT WILL WORK TO SUPPRESS ANY
NORTHWARD MOVEMENT. THE NAM WANTS TO PUSH THE FRONT QUICKLY NORTH IN
THE 1ST HALF OF THE DAY...AN INTERNALLY INCONSISTENT APPROACH SINCE
IT IS ALSO AMONG THE WETTEST SOLUTIONS NORTH OF THE FRONT THIS
MORNING. THE RAP OFFERS A BETTER ALTERNATIVE IN THE NEAR-TERM...WITH
THE FRONT REACHING A MANTON-HARRISVILLE LINE BY MIDDAY...BEFORE
GETTING ABRUPTLY SHOVED SOUTHWARD AGAIN AS PRECIP BECOMES MORE
EXPANSIVE.
SPEAKING OF WHICH...THERE ARE A PAIR OF SHORTWAVES MOVING EAST
TOWARD THE LAKES REGION EARLY THIS MORNING...ONE IN W CENTRAL WI AND
THE 2ND IN NW IL. THESE WILL BOTH ACT TO PROVIDE FORCING FOR ASCENT
JUST AFTER SUNRISE IN WESTERN SECTIONS. HOWEVER...AT THIS TIME OF
DAY NEITHER HAS MUCH IN THE WAY OF INSTABILITY TO WORK WITH. NOTE
THAT ACTIVITY MOVING ENE OUT OF CHICAGO IS FIZZLING RAPIDLY OVER
SOUTHERN LAKE MI. GENERALLY THINK THAT...THRU 10AM...THE MAIN PRECIP
CHANCES WILL BE WEST OF TVC/CAD...IN EASTERN UPPER MI...AND IN
PARTS OF NE LOWER (IF DOWNSTATE ACTIVITY DEVELOPS NE-WARD AS
AGGRESSIVELY AS RECENT RAP RUNS SUGGEST).
HOWEVER...WE HAVE PLENTY OF MOISTURE (PWATS 1.5-1.7) AND SOME
FORCING FOR ASCENT AVAILABLE. SO IT WILL TAKE VERY LITTLE HEATING
(EVEN WITH CONSIDERABLE CLOUD COVER) TO PRIME THE AIRMASS FOR
CONVECTION. THIS IS ESPECIALLY THE CASE GIVEN THAT (AS OPPOSED TO
YESTERDAY) WE ACTUALLY HAVE CROSS-FRONTAL 1000-850MB FLOW.
ANTICIPATE SHRA WILL RAPIDLY EXPAND IN COVERAGE OVER NW LOWER MI
BETWEEN 10AM AND NOON. FURTHER EXPANSION ACROSS THE BULK OF NORTHERN
LOWER WILL OCCUR AS ACTIVITY CONTINUES TO PERCOLATE THRU THE
AFTERNOON. SOME OF THIS ACTIVITY WILL LEAK INTO EASTERN UPPER...BUT
THAT FAR NORTH OF THE WARM FRONT SUSPECT COVERAGE THERE WILL BE LESS
THAN THE NAM/GFS ARGUE. CONVECTION WILL BE QUICK TO TRIGGER...SO WE
WON/T REALLY GET THE CHANCE TO BUILD UP MUCH IN THE WAY OF CAPE.
MLCAPES SHOULD STAY LESS THAN 500J/KG. THIS WILL KEEP PRECIP MAINLY
AS SHRA...WITH A FEW EMBEDDED TSRA...AND NO SVR THREAT. LOCALIZED
RAINFALL AMOUNTS OF A QUARTER TO HALF AN INCH WILL BE SEEN.
WILL BE A MUGGY DAY...BUT TEMPS WILL BE SHARPLY LIMITED BY
CLOUDS/PRECIP. HIGHS WILL BE MAINLY IN THE 70S...PEAKING UP CLOSE TO
80F IN A FEW SPOTS.
TONIGHT...PRIMARY 500MB CIRCULATION CLOSES OFF AND DEEPENS AS IT
MOVES FROM EASTERN SD TO SOUTHERN MN. THE CORRESPONDING SURFACE LOW
WILL DEEPEN TO 994MB AS IT MOVES TO THE MN/WI BORDER. IN ADVANCE OF
THIS DEVELOPING CYCLONE...SOUTHERLY 850MB WINDS WILL INCREASE TO 20-
30KT. THIS WILL PUSH THE SURFACE WARM FRONT MORE EMPHATICALLY
NORTHWARD TOWARD FAR NORTHERN LOWER OR THE STRAITS REGION. CHANCES
FOR PRECIP WILL DECREASE BEHIND THE FRONT. SHRA COVERAGE WILL BE
CONSIDERABLE ACROSS THE FORECAST AREA IN THE EVENING...BUT POPS WILL
DECREASE (THOUGH NOT DISAPPEAR) SOUTH OF M-32 OVERNIGHT. IN
ADDITION...IT IS LIKELY OVERNIGHT THAT ONE OR MORE MCS/S WILL BE
MOVING EAST IN THE WARM SECTOR INTO THE SW LAKES REGION. DON/T THINK
THAT THESE WILL HOLD TOGETHER AND REACH SW SECTIONS TOWARD
DAYBREAK...BUT IT/S NOT IMPOSSIBLE. THAT/S OUR VERY LOW-END SHOT AT
ANYTHING SVR...OTHERWISE MLCAPE IS TOO LIMITED.
STILL MUGGY AND A VERY WARM NIGHT...WITH LOWS IN THE MID 60S TO
AROUND 70F.
&&
.SHORT TERM...(WEDNESDAY THROUGH THURSDAY NIGHT)
ISSUED AT 328 AM EDT TUE AUG 18 2015
LOW PRESSURE EMERGES OUT OF THE CENTRAL PLAINS TODAY THEN HEADS
NORTHEAST INTO THE NORTHERN MISSISSIPPI VALLEY WHILE DEEPENING. THE
IMPACTS FROM THIS SYSTEM WILL BE THE FOCUS OF THE FORECAST WITH THE
MAIN CHALLENGE BEING THE POTENTIAL FOR SEVERE STORMS WEDNESDAY.
WEDNESDAY...THE TRACK OF A NEGATIVELY TILTED TROUGH AND ASSOCIATED
AREA OF DEEPENING LOW PRESSURE TO OUR NORTHWEST IS EXPECTED TO LEAD
TO A SOLID AREA OF SHOWERS ACROSS EASTERN UPPER AND FAR NORTHWEST
LOWER WEDNESDAY WITH SLIGHTLY LESSER BUT MORE CONVECTIVE
SHOWER/STORM COVERAGE ACROSS SOUTHEAST ZONES. THERE IS A THREAT FOR
SEVERE STORMS...MAINLY BECAUSE OF STRONGER WINDS ALOFT (NAM 0-6KM
BULK SHEAR 30 TO 40 KNOTS WITH THE MORE BULLISH GFS A ROBUST 50 TO
55 KNOTS!). IN ADDITION TO THE STRONG WINDS ALOFT NORTHEAST LOWER
MAY ALSO GET INTO HEALTHY AMOUNTS OF INSTABILITY IF THE SUN IS ABLE
TO BREAK OUT IN THE DRY SLOT. SO NOT SURPRISINGLY...SPC HAS JUST
PLACED ALL OF NORTHERN LOWER IN A SLIGHT RISK FOR WIND AND/OR HAIL.
MODELS CONTINUE TO DIFFER ON THE FINER DETAILS OF THIS SYSTEM
INCLUDING TIMING AND STRENGTH (THOUGH BOTH THE ECMWF AND GFS ARE
TRENDING STRONGER) SO STAY TUNED FOR FURTHER UPDATES AS THIS
POSSIBLE EVENT GETS A LITTLE CLOSER. A SYSTEM THIS DEEP THIS TIME OF
THE YEAR IS A BIT UNUSUAL SO THINGS HAVE THE POTENTIAL TO GET
INTERESTING. HIGHS RANGING FROM THE MUGGY UPPER 70S NORTH TO PERHAPS
THE TOASTY UPPER 80S SOUTHEAST ZONES.
WEDNESDAY NIGHT...A FEW MORE SHOWERS (AND THUNDERSTORMS EAST) ARE
LIKELY AS THE COLD FRONT ASSOCIATED WITH THE LOW PRESSURE SYSTEM
MOVES ACROSS THE REGION (ACTUALLY IT MAY BE MORE OF AN OCCLUDED
FRONT AT THAT POINT). LOWS RANGING FROM THE UPPER 50S TO MIDDLE 60S.
THURSDAY...WRAP AROUND SHOWERS ARE POSSIBLE ACROSS EASTERN UPPER AND
FAR NORTHERN LOWER...ESPECIALLY IN THE MORNING. COOLER WITH HIGHS
ONLY IN THE UPPER 60S AND LOWER 70S.
&&
.LONG TERM...(FRIDAY THROUGH MONDAY)
ISSUED AT 328 AM EDT TUE AUG 18 2015
HIGH PRESSURE BUILDS IN FRIDAY WHICH SHOULD HOLD ON THROUGH SATURDAY
NIGHT YIELDING WARMER AND DRIER CONDITIONS. ANOTHER AREA OF LOW
PRESSURE TRACKING BY TO OUR NORTHWEST WILL THEN BRING MORE CHANCES
FOR SHOWERS AND THUNDERSTORMS SUNDAY...WITH WRAP AROUND DRIVEN
SHOWERS POSSIBLY LINGERING INTO MONDAY (MODELS ARE NOT IN AGREEMENT
HERE BUT PLENTY OF TIME TO MAKE ADJUSTMENTS). HIGHS BACK IN THE
UPPER 70S AND LOWER 80S FRIDAY THROUGH SUNDAY. COOLER AGAIN FOR
MONDAY WITH HIGHS IN THE UPPER 60S AND LOWER 70S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 113 PM EDT TUE AUG 18 2015
MVFR/LOW VFR CIGS WILL HOLD OVER ALL NRN LWR MICHIGAN TAF SITES
THRU TONIGHT AS A STALLED WARM FRONT TRIES TO LIFT THRU THE
REGION. SCT/NMRS SHOWERS AND AN ISOLD THUNDERSTORM WILL CONTINUE
TO DRIFT THRU THE REGION THIS AFTERNOON AND TONIGHT ALONG AND
NORTH OF THE WARM FRONT. WINDS WILL REMAIN FROM THE E/SE UNDER 10
KTS THRU TONIGHT...BUT WILL STRENGTHEN AND SWITCH TO THE S/SW ON
WEDNESDAY AS DEEP LOW PRESSURE LIFTS INTO WRN UPR MICHIGAN AND A
COLD FRONT SWEEPS THRU ERN UPR AND LWR MICHIGAN. THIS SYSTEM WILL
INCREASE OUR CHANCES OF SHOWERS AND STORMS...AND MAY PRODUCE SOME
STRONG/SVR STORMS ON WEDNESDAY. OVERALL CONDITIONS WILL REMAIN
MVFR/LOW VFR AS THIS SYSTEM IMPACT THE REGION ON WEDNESDAY. CIGS
AND VSBYS WILL BE LOWER WITHIN ANY THUNDERSTORMS.
&&
.MARINE...
ISSUED AT 328 AM EDT TUE AUG 18 2015
A STALLED FRONT WILL WOBBLE ACROSS CENTRAL LOWER MI TODAY...BEFORE
MOVING NORTH TONIGHT AS A WARM FRONT. SE-ERLY WINDS WILL BE LIGHT
THRU THIS EVENING...BUT INCREASE OVERNIGHT. SMALL CRAFT
ADVISORIES WILL LIKELY BE NEEDED ON SOME WATERS BY WEDNESDAY
AFTERNOON. A STRONG COLD FRONT WILL CROSS THE REGION LATE
WEDNESDAY...WITH STRONG TO POTENTIALLY SVR THUNDERSTORMS.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...MLR
NEAR TERM...JAZ
SHORT TERM...SULLIVAN
LONG TERM...SULLIVAN
AVIATION...MLR
MARINE...JAZ
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1033 AM EDT TUE AUG 18 2015
.UPDATE...
ISSUED AT 1033 AM EDT TUE AUG 18 2015
SCT/NMRS SHOWERS CONTINUE TO DEVELOP ACROSS MUCH OF THE WRN GREAT
LAKES LATE THIS MORNING...INCLUDING OUR CWA WHERE SOME BRIEF ISOLD
THUNDER HAS ALSO DEVELOPED PER RECENT LIGHTNING DATA. FORCING
REMAINS WEAK...WITH LITTLE IN THE WAY TO ORGANIZE ANY OF THE
CONVECTION. WARM FRONT IS TRYING TO PUSH NORTHWARD INTO SRN
SECTIONS OF OUR CWA...BUT IS MAKING LITTLE PROGRESS GIVEN THICK
CLOUD COVER AND PRECIP ACROSS OUR AREA. CLOUDS AND PRECIP ARE ALSO
GREATLY LIMITING THE POTENTIAL FOR INCREASED INSTABILITY AS THE
DAY SLOWLY HEATS UP. ALL OF THE ABOVE WILL REMAIN IN PLACE THRU
THE AFTERNOON...WHICH WILL CONTINUE TO LIMIT OUR THUNDER CHANCES.
HOWEVER...DO STILL EXPECT PRECIP ITSELF WILL GRADUALLY EXPAND
THANKS TO SOME DIURNALLY-ENHANCED INSTABILITY AND AMPLE MOISTURE
POOLING ALONG AND NORTH OF THE WARM FRONT. HAVE MADE ONLY MINOR
ADJUSTMENTS TO WX/POP FORECAST FOR THE AFTERNOON. OVERALL...EXPECT
A MAINLY CLOUDY AFTERNOON WITH WAVES OF SHOWERS AND POSSIBLY A FEW
THUNDERSTORMS...WITH THE HIGHEST POPS ACROSS NRN LWR MICHIGAN.
&&
.NEAR TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 328 AM EDT TUE AUG 18 2015
HIGH IMPACT WEATHER POTENTIAL...NON-SEVERE THUNDERSTORMS TODAY AND
TONIGHT.
DIFFUSE COLD FRONT RESTS ROUGHLY FROM OSC TO MBL. THIS FRONT IS
STALLING OUT...AS LEE CYCLOGENESIS GETS UNDERWAY IN THE CENTRAL
HIGH PLAINS. SOME SHRA ARE SEEN OVER CENTRAL/NORTHERN LAKE MI AND
SURROUNDING AREAS. A FEW SHRA HAVE ALSO RECENTLY DEVELOPED JUST SW
OF LAN. NO THUNDER LEFT IN OUR NECK OF THE WOODS. THE FRONT WILL
WOBBLE ACROSS CENTRAL/NORTHERN LOWER MI OVER THE NEXT 24
HOURS...AS HEATING/CONVECTION/SOUTHERLY FLOW WAXES AND WANES.
PRECIP TRENDS ARE THE MAIN CONCERN.
TODAY...A POTENT SHORTWAVE WILL DIG FROM THE NORTHERN TO CENTRAL
HIGH PLAINS TODAY. IN RESPONSE...PRESSURES WILL RAPIDLY FALL IN THE
CENTRAL PLAINS. BY MID-EVENING...A SUB-1000MB LOW WILL BE MOVING
INTO NW IOWA. SOUTHERLY 1000-850MB FLOW INTO LOWER MI WILL INCREASE
TO SOME DEGREE...THOUGH THE TIGHTEST PRESSURE GRADIENT WILL REMAIN
TO OUR WEST THRU 00Z. STILL...THAT AND DIURNAL HEATING/MIXING WILL
TEND TO PUSH THE FRONT NORTH. HOWEVER...PRECIP AND SUBSEQUENT COLD-
POOL GENERATION NORTH OF THE FRONT WILL WORK TO SUPPRESS ANY
NORTHWARD MOVEMENT. THE NAM WANTS TO PUSH THE FRONT QUICKLY NORTH IN
THE 1ST HALF OF THE DAY...AN INTERNALLY INCONSISTENT APPROACH SINCE
IT IS ALSO AMONG THE WETTEST SOLUTIONS NORTH OF THE FRONT THIS
MORNING. THE RAP OFFERS A BETTER ALTERNATIVE IN THE NEAR-TERM...WITH
THE FRONT REACHING A MANTON-HARRISVILLE LINE BY MIDDAY...BEFORE
GETTING ABRUPTLY SHOVED SOUTHWARD AGAIN AS PRECIP BECOMES MORE
EXPANSIVE.
SPEAKING OF WHICH...THERE ARE A PAIR OF SHORTWAVES MOVING EAST
TOWARD THE LAKES REGION EARLY THIS MORNING...ONE IN W CENTRAL WI AND
THE 2ND IN NW IL. THESE WILL BOTH ACT TO PROVIDE FORCING FOR ASCENT
JUST AFTER SUNRISE IN WESTERN SECTIONS. HOWEVER...AT THIS TIME OF
DAY NEITHER HAS MUCH IN THE WAY OF INSTABILITY TO WORK WITH. NOTE
THAT ACTIVITY MOVING ENE OUT OF CHICAGO IS FIZZLING RAPIDLY OVER
SOUTHERN LAKE MI. GENERALLY THINK THAT...THRU 10AM...THE MAIN PRECIP
CHANCES WILL BE WEST OF TVC/CAD...IN EASTERN UPPER MI...AND IN
PARTS OF NE LOWER (IF DOWNSTATE ACTIVITY DEVELOPS NE-WARD AS
AGGRESSIVELY AS RECENT RAP RUNS SUGGEST).
HOWEVER...WE HAVE PLENTY OF MOISTURE (PWATS 1.5-1.7) AND SOME
FORCING FOR ASCENT AVAILABLE. SO IT WILL TAKE VERY LITTLE HEATING
(EVEN WITH CONSIDERABLE CLOUD COVER) TO PRIME THE AIRMASS FOR
CONVECTION. THIS IS ESPECIALLY THE CASE GIVEN THAT (AS OPPOSED TO
YESTERDAY) WE ACTUALLY HAVE CROSS-FRONTAL 1000-850MB FLOW.
ANTICIPATE SHRA WILL RAPIDLY EXPAND IN COVERAGE OVER NW LOWER MI
BETWEEN 10AM AND NOON. FURTHER EXPANSION ACROSS THE BULK OF NORTHERN
LOWER WILL OCCUR AS ACTIVITY CONTINUES TO PERCOLATE THRU THE
AFTERNOON. SOME OF THIS ACTIVITY WILL LEAK INTO EASTERN UPPER...BUT
THAT FAR NORTH OF THE WARM FRONT SUSPECT COVERAGE THERE WILL BE LESS
THAN THE NAM/GFS ARGUE. CONVECTION WILL BE QUICK TO TRIGGER...SO WE
WON/T REALLY GET THE CHANCE TO BUILD UP MUCH IN THE WAY OF CAPE.
MLCAPES SHOULD STAY LESS THAN 500J/KG. THIS WILL KEEP PRECIP MAINLY
AS SHRA...WITH A FEW EMBEDDED TSRA...AND NO SVR THREAT. LOCALIZED
RAINFALL AMOUNTS OF A QUARTER TO HALF AN INCH WILL BE SEEN.
WILL BE A MUGGY DAY...BUT TEMPS WILL BE SHARPLY LIMITED BY
CLOUDS/PRECIP. HIGHS WILL BE MAINLY IN THE 70S...PEAKING UP CLOSE TO
80F IN A FEW SPOTS.
TONIGHT...PRIMARY 500MB CIRCULATION CLOSES OFF AND DEEPENS AS IT
MOVES FROM EASTERN SD TO SOUTHERN MN. THE CORRESPONDING SURFACE LOW
WILL DEEPEN TO 994MB AS IT MOVES TO THE MN/WI BORDER. IN ADVANCE OF
THIS DEVELOPING CYCLONE...SOUTHERLY 850MB WINDS WILL INCREASE TO 20-
30KT. THIS WILL PUSH THE SURFACE WARM FRONT MORE EMPHATICALLY
NORTHWARD TOWARD FAR NORTHERN LOWER OR THE STRAITS REGION. CHANCES
FOR PRECIP WILL DECREASE BEHIND THE FRONT. SHRA COVERAGE WILL BE
CONSIDERABLE ACROSS THE FORECAST AREA IN THE EVENING...BUT POPS WILL
DECREASE (THOUGH NOT DISAPPEAR) SOUTH OF M-32 OVERNIGHT. IN
ADDITION...IT IS LIKELY OVERNIGHT THAT ONE OR MORE MCS/S WILL BE
MOVING EAST IN THE WARM SECTOR INTO THE SW LAKES REGION. DON/T THINK
THAT THESE WILL HOLD TOGETHER AND REACH SW SECTIONS TOWARD
DAYBREAK...BUT IT/S NOT IMPOSSIBLE. THAT/S OUR VERY LOW-END SHOT AT
ANYTHING SVR...OTHERWISE MLCAPE IS TOO LIMITED.
STILL MUGGY AND A VERY WARM NIGHT...WITH LOWS IN THE MID 60S TO
AROUND 70F.
&&
.SHORT TERM...(WEDNESDAY THROUGH THURSDAY NIGHT)
ISSUED AT 328 AM EDT TUE AUG 18 2015
LOW PRESSURE EMERGES OUT OF THE CENTRAL PLAINS TODAY THEN HEADS
NORTHEAST INTO THE NORTHERN MISSISSIPPI VALLEY WHILE DEEPENING. THE
IMPACTS FROM THIS SYSTEM WILL BE THE FOCUS OF THE FORECAST WITH THE
MAIN CHALLENGE BEING THE POTENTIAL FOR SEVERE STORMS WEDNESDAY.
WEDNESDAY...THE TRACK OF A NEGATIVELY TILTED TROUGH AND ASSOCIATED
AREA OF DEEPENING LOW PRESSURE TO OUR NORTHWEST IS EXPECTED TO LEAD
TO A SOLID AREA OF SHOWERS ACROSS EASTERN UPPER AND FAR NORTHWEST
LOWER WEDNESDAY WITH SLIGHTLY LESSER BUT MORE CONVECTIVE
SHOWER/STORM COVERAGE ACROSS SOUTHEAST ZONES. THERE IS A THREAT FOR
SEVERE STORMS...MAINLY BECAUSE OF STRONGER WINDS ALOFT (NAM 0-6KM
BULK SHEAR 30 TO 40 KNOTS WITH THE MORE BULLISH GFS A ROBUST 50 TO
55 KNOTS!). IN ADDITION TO THE STRONG WINDS ALOFT NORTHEAST LOWER
MAY ALSO GET INTO HEALTHY AMOUNTS OF INSTABILITY IF THE SUN IS ABLE
TO BREAK OUT IN THE DRY SLOT. SO NOT SURPRISINGLY...SPC HAS JUST
PLACED ALL OF NORTHERN LOWER IN A SLIGHT RISK FOR WIND AND/OR HAIL.
MODELS CONTINUE TO DIFFER ON THE FINER DETAILS OF THIS SYSTEM
INCLUDING TIMING AND STRENGTH (THOUGH BOTH THE ECMWF AND GFS ARE
TRENDING STRONGER) SO STAY TUNED FOR FURTHER UPDATES AS THIS
POSSIBLE EVENT GETS A LITTLE CLOSER. A SYSTEM THIS DEEP THIS TIME OF
THE YEAR IS A BIT UNUSUAL SO THINGS HAVE THE POTENTIAL TO GET
INTERESTING. HIGHS RANGING FROM THE MUGGY UPPER 70S NORTH TO PERHAPS
THE TOASTY UPPER 80S SOUTHEAST ZONES.
WEDNESDAY NIGHT...A FEW MORE SHOWERS (AND THUNDERSTORMS EAST) ARE
LIKELY AS THE COLD FRONT ASSOCIATED WITH THE LOW PRESSURE SYSTEM
MOVES ACROSS THE REGION (ACTUALLY IT MAY BE MORE OF AN OCCLUDED
FRONT AT THAT POINT). LOWS RANGING FROM THE UPPER 50S TO MIDDLE 60S.
THURSDAY...WRAP AROUND SHOWERS ARE POSSIBLE ACROSS EASTERN UPPER AND
FAR NORTHERN LOWER...ESPECIALLY IN THE MORNING. COOLER WITH HIGHS
ONLY IN THE UPPER 60S AND LOWER 70S.
&&
.LONG TERM...(FRIDAY THROUGH MONDAY)
ISSUED AT 328 AM EDT TUE AUG 18 2015
HIGH PRESSURE BUILDS IN FRIDAY WHICH SHOULD HOLD ON THROUGH SATURDAY
NIGHT YIELDING WARMER AND DRIER CONDITIONS. ANOTHER AREA OF LOW
PRESSURE TRACKING BY TO OUR NORTHWEST WILL THEN BRING MORE CHANCES
FOR SHOWERS AND THUNDERSTORMS SUNDAY...WITH WRAP AROUND DRIVEN
SHOWERS POSSIBLY LINGERING INTO MONDAY (MODELS ARE NOT IN AGREEMENT
HERE BUT PLENTY OF TIME TO MAKE ADJUSTMENTS). HIGHS BACK IN THE
UPPER 70S AND LOWER 80S FRIDAY THROUGH SUNDAY. COOLER AGAIN FOR
MONDAY WITH HIGHS IN THE UPPER 60S AND LOWER 70S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 655 AM EDT TUE AUG 18 2015
SOME IMPROVEMENT IN FLYING CONDITIONS TODAY. BRIEF VSBY POSSIBLE
AT JUST ABOUT ANY TIME IN SHRA.
STALLED COLD FRONT IS LAID OUT ACROSS CENTRAL LOWER MI. THIS
FRONT WILL WOBBLE ACROSS CENTRAL AND NORTHERN LOWER MI TODAY AND
TONIGHT. CONSIDERABLE SHRA AND A FEW TSRA WILL BE SEEN NORTH OF
THE FRONT...ESPECIALLY FROM LATE MORNING TODAY THRU TONIGHT. BRIEF
VSBY RESTRICTIONS WILL BE POSSIBLE. APN IS CURRENTLY IFR...OTHER
SITES VFR. APN WILL SEE IMPROVEMENT AS THE DAY PROCEEDS.
WINDS WILL BE LIGHT SOUTHERLY TO EASTERLY.
&&
.MARINE...
ISSUED AT 328 AM EDT TUE AUG 18 2015
A STALLED FRONT WILL WOBBLE ACROSS CENTRAL LOWER MI TODAY...BEFORE
MOVING NORTH TONIGHT AS A WARM FRONT. SE-ERLY WINDS WILL BE LIGHT
THRU THIS EVENING...BUT INCREASE OVERNIGHT. SMALL CRAFT
ADVISORIES WILL LIKELY BE NEEDED ON SOME WATERS BY WEDNESDAY
AFTERNOON. A STRONG COLD FRONT WILL CROSS THE REGION LATE
WEDNESDAY...WITH STRONG TO POTENTIALLY SVR THUNDERSTORMS.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...MLR
NEAR TERM...JAZ
SHORT TERM...SULLIVAN
LONG TERM...SULLIVAN
AVIATION...JAZ
MARINE...JAZ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
745 AM EDT TUE AUG 18 2015
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 500 AM EDT TUE AUG 18 2015
WV IMAGERY AND RAP ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM NRN HUDSON BAY INTO THE NRN PLAINS RESULTING IN WNW FLOW
THROUGH THE NRN GREAT LAKES. A WEAK SHORTWAVE TROUGH AND AREA OF 850-
700 MB FGEN SUPPORTED A BAND OF SHOWERS OVER WRN UPPER MI. UPSTREAM
A VIGOROUS SHRTWV WAS MOVING THROUGH SD/NE. AT THE SFC...A WEAK
FRONTAL BOUNDARY EXTENDED FROM CNTRL LOWER MI THROUGH SE WI AND SW
IA TO LOW PRES OVER NRN KS. WITH HIGH PRES OVER NRN ONTARIO...LIGHT
NE WINDS PREVAILED ACROSS THE NRN LAKES.
EXPECT THE PCPN OVER THE WEST TO DIMINISH EARLY AS THE SHRTWV AND
FGEN LIFT MOVE OFF TO THE NORTHEAST. HOWEVER...SOME SCT -SHRA MAY
LINGER OVER THE SOUTH AS ANOTHER WEAK SHRTWV BRUSHES THE AREA TO THE
SE.
ATTENTION...WILL THEN TURN TO THE DEVELOPING AND UNSEASONABLY STRONG
LOW PRES SYSTEM MOVING OUT OF THE PLAINS. THE SD/NE SHRTWV WILL
SUPPORT A DEEPENING LOW MOVING INTO THE NW CORNER OF IA BY 00Z/WED
AND ERN MN BY 12Z/WED. THE MODELS HAVE TRENDED TOWARD A SLIGHTLY
SLOWER PROGRESSION OF THE LOW AS THE STRONG JET MOVING OUT OF THE
PLAINS HELPS CUT OFF THE MID LEVEL LOW. AN AREA OF STRONG MOISTURE
TRANSPORT AND 305K-310K ISENTROPIC ASCENT WILL BRING AN AREA OF RAIN
THROUGH UPPER MI TONIGHT...MAINLY AFTER MIDNIGHT. HOWEVER...THIS
TRANSIENT BAND IS EXPECTED TO BRING QPF AMOUNTS ONLY IN THE 0.25-
0.50 INCH RANGE OVER THE CNTRL AND ERN CWA. HIGHER AMOUNTS TO AROUND
AN INCH WILL BE POSSIBLE OVER THE FAR WEST CLOSER TO THE STRONGEST
DEEP LAYER QVECTOR CONV AND LIFT WHICH WILL REMAIN TO THE WEST OVER
NRN MN AND WRN LAKE SUPERIOR. WITH MODEST MUCAPE VALUES INTO THE 200-
400 J/KG RANGE ONLY ISOLD TSRA ARE EXPECTED.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 339 AM EDT TUE AUG 18 2015
BY 12Z WED AN INTENSIFYING LOW WILL BE APPROACHING OR OVER THE WRN
CWA. THE 00Z/18 GFS HAS COME INTO GOOD AGREEMENT WITH THE 12Z/17
ECMWF IN DEEPENING THE SFC LOW TO 993-995MB AS THE SYSTEM CLOSES OFF
OVER WRN LAKE SUPERIOR WED. THE NAM . BY 12Z THU THE LOW WILL BE
OCCLUDED N OF LAKE SUPERIOR AND WILL QUICKLY SHUNT N TO HUDSON BAY
BY 00Z FRI.
OVERALL EXPECTATIONS HAVE NOT CHANGED MUCH FROM THE DAY SHIFT MON. A
SURGE OF PRECIP WILL BE EXITING N WED MORNING AHEAD OF THE COLD
FRONT AND THEN DRY SLOT THAT WILL MOVE IN FROM THE SW WED LATE
MORNING/AFTERNOON. COULD SEE SOME STRONG TO POSSIBLY SEVERE STORMS
ALONG THE COLD FRONT AS EFFECTIVE SHEAR IS ENHANCED...BUT OTHERWISE
NOT EXPECTING SEVERE STORMS. AFTER THE DRY SLOT MOVES INTO MAINLY
THE CENTRAL AND ERN CWA...WRAP AROUND PRECIP/MOISTURE WILL MOVE INTO
WRN UPPER MI. THE WRAP AROUND PRECIP WILL SPREAD TO NRN AND WRN
UPPER MI WED NIGHT AND CONTINUE THROUGH MOST OF THU. WED LOOKS WINDY
WITH S-SW WINDS GUSTING TO 25-35 MPH. WINDS THU WILL BE SIMILAR
STRENGTH OF WED...BUT OUT OF THE W.
FRI AND SAT LOOK DRY WITH SW FLOW ALONG AND A SFC HIGH OVER MUCH OF
THE ERN CONUS. HOWEVER...MODELS CONTINUE TO INDICATE THAT ANOTHER
STORM SYSTEM COULD BRING PRECIP SUN INTO MON...BUT DETAILS REMAIN
UNCLEAR AT THIS TIME.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 742 AM EDT TUE AUG 18 2015
MAINLY MVFR CIGS ARE EXPECTED AT SAW WITH CONTINUED MOIST UPSLOPE NE
FLOW TODAY. CIGS SHOULD ALSO LOWER AT IWD AND CMX BUT WITH DRIER AIR
IN PLACE...EXPECT CONDITIONS TO REMAIN VFR UNTIL LATER THIS
AFTERNOON. A STRENGTHENING ESE FLOW AHEAD OF DEEPENING LO PRES IN
THE PLAINS WL BRING A RETURN OF MORE WDSPRD -RA/MVFR CONDITIONS IN
THE EVENING DROPPING TO IFR OVERNIGHT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 514 AM EDT TUE AUG 18 2015
HIGH PRES STRETCHING FROM SOUTHERN MANITOBA THROUGH JAMES BAY WILL
EXTEND A RIDGE INTO THE UPPER LAKES THROUGH THIS MORNING...RESULTING
IN LIGHT WINDS UNDER 15KT ACROSS LAKE SUPERIOR. THEN...AS LOW PRES
ORGANIZES AND STRENGTHENS OVER THE PLAINS TUE...NE WINDS WILL BEGIN
TO INCREASE...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE GUSTS SHOULD
REACH 25-30KT LATE AFTN/EARLY EVENING. THIS LOW WILL BECOME
UNSEASONABLY DEEP FOR AUG AS IT LIFTS ACROSS FAR WRN LAKE SUPERIOR
WED AFTERNOON. 20-30KT WINDS ARE EXPECTED OVER MUCH OF THE LAKE
TONIGHT INTO WED. MAY SEE GALE FORCE GUSTS OVER FAR WRN LAKE SUPERIOR
IN THE NE WINDS AHEAD OF THE LOW TONIGHT AND THEN IN THE WESTERLY
WINDS ACROSS MAINLY CENTRAL LAKE SUPERIOR ON THU AS THE LOW LIFTS N
OF THE AREA. WINDS WILL DIMINISH TO UNDER 20KT FRI...AND THEN BEGIN
TO INCREASE AGAIN ON SAT AHEAD OF THE NEXT COLD FRONT MOVING OUT
ACROSS THE PLAINS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...TITUS
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS GAYLORD MI
654 AM EDT TUE AUG 18 2015
.NEAR TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 328 AM EDT TUE AUG 18 2015
HIGH IMPACT WEATHER POTENTIAL...NON-SEVERE THUNDERSTORMS TODAY AND
TONIGHT.
DIFFUSE COLD FRONT RESTS ROUGHLY FROM OSC TO MBL. THIS FRONT IS
STALLING OUT...AS LEE CYCLOGENESIS GETS UNDERWAY IN THE CENTRAL
HIGH PLAINS. SOME SHRA ARE SEEN OVER CENTRAL/NORTHERN LAKE MI AND
SURROUNDING AREAS. A FEW SHRA HAVE ALSO RECENTLY DEVELOPED JUST SW
OF LAN. NO THUNDER LEFT IN OUR NECK OF THE WOODS. THE FRONT WILL
WOBBLE ACROSS CENTRAL/NORTHERN LOWER MI OVER THE NEXT 24
HOURS...AS HEATING/CONVECTION/SOUTHERLY FLOW WAXES AND WANES.
PRECIP TRENDS ARE THE MAIN CONCERN.
TODAY...A POTENT SHORTWAVE WILL DIG FROM THE NORTHERN TO CENTRAL
HIGH PLAINS TODAY. IN RESPONSE...PRESSURES WILL RAPIDLY FALL IN THE
CENTRAL PLAINS. BY MID-EVENING...A SUB-1000MB LOW WILL BE MOVING
INTO NW IOWA. SOUTHERLY 1000-850MB FLOW INTO LOWER MI WILL INCREASE
TO SOME DEGREE...THOUGH THE TIGHTEST PRESSURE GRADIENT WILL REMAIN
TO OUR WEST THRU 00Z. STILL...THAT AND DIURNAL HEATING/MIXING WILL
TEND TO PUSH THE FRONT NORTH. HOWEVER...PRECIP AND SUBSEQUENT COLD-
POOL GENERATION NORTH OF THE FRONT WILL WORK TO SUPPRESS ANY
NORTHWARD MOVEMENT. THE NAM WANTS TO PUSH THE FRONT QUICKLY NORTH IN
THE 1ST HALF OF THE DAY...AN INTERNALLY INCONSISTENT APPROACH SINCE
IT IS ALSO AMONG THE WETTEST SOLUTIONS NORTH OF THE FRONT THIS
MORNING. THE RAP OFFERS A BETTER ALTERNATIVE IN THE NEAR-TERM...WITH
THE FRONT REACHING A MANTON-HARRISVILLE LINE BY MIDDAY...BEFORE
GETTING ABRUPTLY SHOVED SOUTHWARD AGAIN AS PRECIP BECOMES MORE
EXPANSIVE.
SPEAKING OF WHICH...THERE ARE A PAIR OF SHORTWAVES MOVING EAST
TOWARD THE LAKES REGION EARLY THIS MORNING...ONE IN W CENTRAL WI AND
THE 2ND IN NW IL. THESE WILL BOTH ACT TO PROVIDE FORCING FOR ASCENT
JUST AFTER SUNRISE IN WESTERN SECTIONS. HOWEVER...AT THIS TIME OF
DAY NEITHER HAS MUCH IN THE WAY OF INSTABILITY TO WORK WITH. NOTE
THAT ACTIVITY MOVING ENE OUT OF CHICAGO IS FIZZLING RAPIDLY OVER
SOUTHERN LAKE MI. GENERALLY THINK THAT...THRU 10AM...THE MAIN PRECIP
CHANCES WILL BE WEST OF TVC/CAD...IN EASTERN UPPER MI...AND IN
PARTS OF NE LOWER (IF DOWNSTATE ACTIVITY DEVELOPS NE-WARD AS
AGGRESSIVELY AS RECENT RAP RUNS SUGGEST).
HOWEVER...WE HAVE PLENTY OF MOISTURE (PWATS 1.5-1.7) AND SOME
FORCING FOR ASCENT AVAILABLE. SO IT WILL TAKE VERY LITTLE HEATING
(EVEN WITH CONSIDERABLE CLOUD COVER) TO PRIME THE AIRMASS FOR
CONVECTION. THIS IS ESPECIALLY THE CASE GIVEN THAT (AS OPPOSED TO
YESTERDAY) WE ACTUALLY HAVE CROSS-FRONTAL 1000-850MB FLOW.
ANTICIPATE SHRA WILL RAPIDLY EXPAND IN COVERAGE OVER NW LOWER MI
BETWEEN 10AM AND NOON. FURTHER EXPANSION ACROSS THE BULK OF NORTHERN
LOWER WILL OCCUR AS ACTIVITY CONTINUES TO PERCOLATE THRU THE
AFTERNOON. SOME OF THIS ACTIVITY WILL LEAK INTO EASTERN UPPER...BUT
THAT FAR NORTH OF THE WARM FRONT SUSPECT COVERAGE THERE WILL BE LESS
THAN THE NAM/GFS ARGUE. CONVECTION WILL BE QUICK TO TRIGGER...SO WE
WON/T REALLY GET THE CHANCE TO BUILD UP MUCH IN THE WAY OF CAPE.
MLCAPES SHOULD STAY LESS THAN 500J/KG. THIS WILL KEEP PRECIP MAINLY
AS SHRA...WITH A FEW EMBEDDED TSRA...AND NO SVR THREAT. LOCALIZED
RAINFALL AMOUNTS OF A QUARTER TO HALF AN INCH WILL BE SEEN.
WILL BE A MUGGY DAY...BUT TEMPS WILL BE SHARPLY LIMITED BY
CLOUDS/PRECIP. HIGHS WILL BE MAINLY IN THE 70S...PEAKING UP CLOSE TO
80F IN A FEW SPOTS.
TONIGHT...PRIMARY 500MB CIRCULATION CLOSES OFF AND DEEPENS AS IT
MOVES FROM EASTERN SD TO SOUTHERN MN. THE CORRESPONDING SURFACE LOW
WILL DEEPEN TO 994MB AS IT MOVES TO THE MN/WI BORDER. IN ADVANCE OF
THIS DEVELOPING CYCLONE...SOUTHERLY 850MB WINDS WILL INCREASE TO 20-
30KT. THIS WILL PUSH THE SURFACE WARM FRONT MORE EMPHATICALLY
NORTHWARD TOWARD FAR NORTHERN LOWER OR THE STRAITS REGION. CHANCES
FOR PRECIP WILL DECREASE BEHIND THE FRONT. SHRA COVERAGE WILL BE
CONSIDERABLE ACROSS THE FORECAST AREA IN THE EVENING...BUT POPS WILL
DECREASE (THOUGH NOT DISAPPEAR) SOUTH OF M-32 OVERNIGHT. IN
ADDITION...IT IS LIKELY OVERNIGHT THAT ONE OR MORE MCS/S WILL BE
MOVING EAST IN THE WARM SECTOR INTO THE SW LAKES REGION. DON/T THINK
THAT THESE WILL HOLD TOGETHER AND REACH SW SECTIONS TOWARD
DAYBREAK...BUT IT/S NOT IMPOSSIBLE. THAT/S OUR VERY LOW-END SHOT AT
ANYTHING SVR...OTHERWISE MLCAPE IS TOO LIMITED.
STILL MUGGY AND A VERY WARM NIGHT...WITH LOWS IN THE MID 60S TO
AROUND 70F.
&&
.SHORT TERM...(WEDNESDAY THROUGH THURSDAY NIGHT)
ISSUED AT 328 AM EDT TUE AUG 18 2015
LOW PRESSURE EMERGES OUT OF THE CENTRAL PLAINS TODAY THEN HEADS
NORTHEAST INTO THE NORTHERN MISSISSIPPI VALLEY WHILE DEEPENING. THE
IMPACTS FROM THIS SYSTEM WILL BE THE FOCUS OF THE FORECAST WITH THE
MAIN CHALLENGE BEING THE POTENTIAL FOR SEVERE STORMS WEDNESDAY.
WEDNESDAY...THE TRACK OF A NEGATIVELY TILTED TROUGH AND ASSOCIATED
AREA OF DEEPENING LOW PRESSURE TO OUR NORTHWEST IS EXPECTED TO LEAD
TO A SOLID AREA OF SHOWERS ACROSS EASTERN UPPER AND FAR NORTHWEST
LOWER WEDNESDAY WITH SLIGHTLY LESSER BUT MORE CONVECTIVE
SHOWER/STORM COVERAGE ACROSS SOUTHEAST ZONES. THERE IS A THREAT FOR
SEVERE STORMS...MAINLY BECAUSE OF STRONGER WINDS ALOFT (NAM 0-6KM
BULK SHEAR 30 TO 40 KNOTS WITH THE MORE BULLISH GFS A ROBUST 50 TO
55 KNOTS!). IN ADDITION TO THE STRONG WINDS ALOFT NORTHEAST LOWER
MAY ALSO GET INTO HEALTHY AMOUNTS OF INSTABILITY IF THE SUN IS ABLE
TO BREAK OUT IN THE DRY SLOT. SO NOT SURPRISINGLY...SPC HAS JUST
PLACED ALL OF NORTHERN LOWER IN A SLIGHT RISK FOR WIND AND/OR HAIL.
MODELS CONTINUE TO DIFFER ON THE FINER DETAILS OF THIS SYSTEM
INCLUDING TIMING AND STRENGTH (THOUGH BOTH THE ECMWF AND GFS ARE
TRENDING STRONGER) SO STAY TUNED FOR FURTHER UPDATES AS THIS
POSSIBLE EVENT GETS A LITTLE CLOSER. A SYSTEM THIS DEEP THIS TIME OF
THE YEAR IS A BIT UNUSUAL SO THINGS HAVE THE POTENTIAL TO GET
INTERESTING. HIGHS RANGING FROM THE MUGGY UPPER 70S NORTH TO PERHAPS
THE TOASTY UPPER 80S SOUTHEAST ZONES.
WEDNESDAY NIGHT...A FEW MORE SHOWERS (AND THUNDERSTORMS EAST) ARE
LIKELY AS THE COLD FRONT ASSOCIATED WITH THE LOW PRESSURE SYSTEM
MOVES ACROSS THE REGION (ACTUALLY IT MAY BE MORE OF AN OCCLUDED
FRONT AT THAT POINT). LOWS RANGING FROM THE UPPER 50S TO MIDDLE 60S.
THURSDAY...WRAP AROUND SHOWERS ARE POSSIBLE ACROSS EASTERN UPPER AND
FAR NORTHERN LOWER...ESPECIALLY IN THE MORNING. COOLER WITH HIGHS
ONLY IN THE UPPER 60S AND LOWER 70S.
&&
.LONG TERM...(FRIDAY THROUGH MONDAY)
ISSUED AT 328 AM EDT TUE AUG 18 2015
HIGH PRESSURE BUILDS IN FRIDAY WHICH SHOULD HOLD ON THROUGH SATURDAY
NIGHT YIELDING WARMER AND DRIER CONDITIONS. ANOTHER AREA OF LOW
PRESSURE TRACKING BY TO OUR NORTHWEST WILL THEN BRING MORE CHANCES
FOR SHOWERS AND THUNDERSTORMS SUNDAY...WITH WRAP AROUND DRIVEN
SHOWERS POSSIBLY LINGERING INTO MONDAY (MODELS ARE NOT IN AGREEMENT
HERE BUT PLENTY OF TIME TO MAKE ADJUSTMENTS). HIGHS BACK IN THE
UPPER 70S AND LOWER 80S FRIDAY THROUGH SUNDAY. COOLER AGAIN FOR
MONDAY WITH HIGHS IN THE UPPER 60S AND LOWER 70S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 655 AM EDT TUE AUG 18 2015
SOME IMPROVEMENT IN FLYING CONDITIONS TODAY. BRIEF VSBY POSSIBLE
AT JUST ABOUT ANY TIME IN SHRA.
STALLED COLD FRONT IS LAID OUT ACROSS CENTRAL LOWER MI. THIS
FRONT WILL WOBBLE ACROSS CENTRAL AND NORTHERN LOWER MI TODAY AND
TONIGHT. CONSIDERABLE SHRA AND A FEW TSRA WILL BE SEEN NORTH OF
THE FRONT...ESPECIALLY FROM LATE MORNING TODAY THRU TONIGHT. BRIEF
VSBY RESTRICTIONS WILL BE POSSIBLE. APN IS CURRENTLY IFR...OTHER
SITES VFR. APN WILL SEE IMPROVEMENT AS THE DAY PROCEEDS.
WINDS WILL BE LIGHT SOUTHERLY TO EASTERLY.
&&
.MARINE...
ISSUED AT 328 AM EDT TUE AUG 18 2015
A STALLED FRONT WILL WOBBLE ACROSS CENTRAL LOWER MI TODAY...BEFORE
MOVING NORTH TONIGHT AS A WARM FRONT. SE-ERLY WINDS WILL BE LIGHT
THRU THIS EVENING...BUT INCREASE OVERNIGHT. SMALL CRAFT
ADVISORIES WILL LIKELY BE NEEDED ON SOME WATERS BY WEDNESDAY
AFTERNOON. A STRONG COLD FRONT WILL CROSS THE REGION LATE
WEDNESDAY...WITH STRONG TO POTENTIALLY SVR THUNDERSTORMS.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
NEAR TERM...JAZ
SHORT TERM...SULLIVAN
LONG TERM...SULLIVAN
AVIATION...JAZ
MARINE...JAZ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
514 AM EDT TUE AUG 18 2015
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 500 AM EDT TUE AUG 18 2015
WV IMAGERY AND RAP ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM NRN HUDSON BAY INTO THE NRN PLAINS RESULTING IN WNW FLOW
THROUGH THE NRN GREAT LAKES. A WEAK SHORTWAVE TROUGH AND AREA OF 850-
700 MB FGEN SUPPORTED A BAND OF SHOWERS OVER WRN UPPER MI. UPSTREAM
A VIGOROUS SHRTWV WAS MOVING THROUGH SD/NE. AT THE SFC...A WEAK
FRONTAL BOUNDARY EXTENDED FROM CNTRL LOWER MI THROUGH SE WI AND SW
IA TO LOW PRES OVER NRN KS. WITH HIGH PRES OVER NRN ONTARIO...LIGHT
NE WINDS PREVAILED ACROSS THE NRN LAKES.
EXPECT THE PCPN OVER THE WEST TO DIMINISH EARLY AS THE SHRTWV AND
FGEN LIFT MOVE OFF TO THE NORTHEAST. HOWEVER...SOME SCT -SHRA MAY
LINGER OVER THE SOUTH AS ANOTHER WEAK SHRTWV BRUSHES THE AREA TO THE
SE.
ATTENTION...WILL THEN TURN TO THE DEVELOPING AND UNSEASONABLY STRONG
LOW PRES SYSTEM MOVING OUT OF THE PLAINS. THE SD/NE SHRTWV WILL
SUPPORT A DEEPENING LOW MOVING INTO THE NW CORNER OF IA BY 00Z/WED
AND ERN MN BY 12Z/WED. THE MODELS HAVE TRENDED TOWARD A SLIGHTLY
SLOWER PROGRESSION OF THE LOW AS THE STRONG JET MOVING OUT OF THE
PLAINS HELPS CUT OFF THE MID LEVEL LOW. AN AREA OF STRONG MOISTURE
TRANSPORT AND 305K-310K ISENTROPIC ASCENT WILL BRING AN AREA OF RAIN
THROUGH UPPER MI TONIGHT...MAINLY AFTER MIDNIGHT. HOWEVER...THIS
TRANSIENT BAND IS EXPECTED TO BRING QPF AMOUNTS ONLY IN THE 0.25-
0.50 INCH RANGE OVER THE CNTRL AND ERN CWA. HIGHER AMOUNTS TO AROUND
AN INCH WILL BE POSSIBLE OVER THE FAR WEST CLOSER TO THE STRONGEST
DEEP LAYER QVECTOR CONV AND LIFT WHICH WILL REMAIN TO THE WEST OVER
NRN MN AND WRN LAKE SUPERIOR. WITH MODEST MUCAPE VALUES INTO THE 200-
400 J/KG RANGE ONLY ISOLD TSRA ARE EXPECTED.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 339 AM EDT TUE AUG 18 2015
BY 12Z WED AN INTENSIFYING LOW WILL BE APPROACHING OR OVER THE WRN
CWA. THE 00Z/18 GFS HAS COME INTO GOOD AGREEMENT WITH THE 12Z/17
ECMWF IN DEEPENING THE SFC LOW TO 993-995MB AS THE SYSTEM CLOSES OFF
OVER WRN LAKE SUPERIOR WED. THE NAM . BY 12Z THU THE LOW WILL BE
OCCLUDED N OF LAKE SUPERIOR AND WILL QUICKLY SHUNT N TO HUDSON BAY
BY 00Z FRI.
OVERALL EXPECTATIONS HAVE NOT CHANGED MUCH FROM THE DAY SHIFT MON. A
SURGE OF PRECIP WILL BE EXITING N WED MORNING AHEAD OF THE COLD
FRONT AND THEN DRY SLOT THAT WILL MOVE IN FROM THE SW WED LATE
MORNING/AFTERNOON. COULD SEE SOME STRONG TO POSSIBLY SEVERE STORMS
ALONG THE COLD FRONT AS EFFECTIVE SHEAR IS ENHANCED...BUT OTHERWISE
NOT EXPECTING SEVERE STORMS. AFTER THE DRY SLOT MOVES INTO MAINLY
THE CENTRAL AND ERN CWA...WRAP AROUND PRECIP/MOISTURE WILL MOVE INTO
WRN UPPER MI. THE WRAP AROUND PRECIP WILL SPREAD TO NRN AND WRN
UPPER MI WED NIGHT AND CONTINUE THROUGH MOST OF THU. WED LOOKS WINDY
WITH S-SW WINDS GUSTING TO 25-35 MPH. WINDS THU WILL BE SIMILAR
STRENGTH OF WED...BUT OUT OF THE W.
FRI AND SAT LOOK DRY WITH SW FLOW ALONG AND A SFC HIGH OVER MUCH OF
THE ERN CONUS. HOWEVER...MODELS CONTINUE TO INDICATE THAT ANOTHER
STORM SYSTEM COULD BRING PRECIP SUN INTO MON...BUT DETAILS REMAIN
UNCLEAR AT THIS TIME.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 125 AM EDT TUE AUG 18 2015
ALTHOUGH SOME -SHRA MAY IMPACT IWD AND PERHAPS CMX LATER...THERE
SHOULD BE ENUF LLVL DRY AIR TO MAINTAIN VFR CONDITIONS. AT SAW...AN
UPSLOPE NE FLOW CLOSER TO STALLED FNT JUST TO THE SE OF UPR MI IN
THE PRESENCE OF NOCTURNAL COOLING WL RESULT IN A DEVELOPMENT OF MVFR
CONDITIONS FOR A TIME THIS MRNG BEFORE DAYTIME HEATING BRINGS A
RETURN OF VFR WX FOR A SHORT TIME. LOWER MVFR CIGS WL RETURN TO THAT
SITE ALONG WITH THE CHC FOR SOME -SHRA LATE IN THE DAY AS THE
STALLED FNT BEGINS MOVING TO THE N. SOME -SHRA WL RETURN TO IWD AS
WELL...BUT DOWNSLOPE NATURE OF THE LLVL WIND THERE SHOULD MAINTAIN
VFR CONDITIONS AT THE ONSET OF ANY PCPN. A STRENGTHENING ESE FLOW
AHEAD OF DEEPENING LO PRES IN THE PLAINS WL BRING A RETURN OF MORE
WDSPRD -RA/MVFR CONDITIONS IN THE EVNG. IFR CONDITIONS WL BE LIKELY
AFTER THE END OF THIS CURRENT TAF PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 514 AM EDT TUE AUG 18 2015
HIGH PRES STRETCHING FROM SOUTHERN MANITOBA THROUGH JAMES BAY WILL
EXTEND A RIDGE INTO THE UPPER LAKES THROUGH THIS MORNING...RESULTING
IN LIGHT WINDS UNDER 15KT ACROSS LAKE SUPERIOR. THEN...AS LOW PRES
ORGANIZES AND STRENGTHENS OVER THE PLAINS TUE...NE WINDS WILL BEGIN
TO INCREASE...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE GUSTS SHOULD
REACH 25-30KT LATE AFTN/EARLY EVENING. THIS LOW WILL BECOME
UNSEASONABLY DEEP FOR AUG AS IT LIFTS ACROSS FAR WRN LAKE SUPERIOR
WED AFTERNOON. 20-30KT WINDS ARE EXPECTED OVER MUCH OF THE LAKE
TONIGHT INTO WED. MAY SEE GALE FORCE GUSTS OVER FAR WRN LAKE SUPERIOR
IN THE NE WINDS AHEAD OF THE LOW TONIGHT AND THEN IN THE WESTERLY
WINDS ACROSS MAINLY CENTRAL LAKE SUPERIOR ON THU AS THE LOW LIFTS N
OF THE AREA. WINDS WILL DIMINISH TO UNDER 20KT FRI...AND THEN BEGIN
TO INCREASE AGAIN ON SAT AHEAD OF THE NEXT COLD FRONT MOVING OUT
ACROSS THE PLAINS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...TITUS
AVIATION...KC
MARINE...JLB
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
503 AM EDT TUE AUG 18 2015
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 500 AM EDT TUE AUG 18 2015
WV IMAGERY AND RAP ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM NRN HUDSON BAY INTO THE NRN PLAINS RESULTING IN WNW FLOW
THROUGH THE NRN GREAT LAKES. A WEAK SHORTWAVE TROUGH AND AREA OF 850-
700 MB FGEN SUPPORTED A BAND OF SHOWERS OVER WRN UPPER MI. UPSTREAM
A VIGOROUS SHRTWV WAS MOVING THROUGH SD/NE. AT THE SFC...A WEAK
FRONTAL BOUNDARY EXTENDED FROM CNTRL LOWER MI THROUGH SE WI AND SW
IA TO LOW PRES OVER NRN KS. WITH HIGH PRES OVER NRN ONTARIO...LIGHT
NE WINDS PREVAILED ACROSS THE NRN LAKES.
EXPECT THE PCPN OVER THE WEST TO DIMINISH EARLY AS THE SHRTWV AND
FGEN LIFT MOVE OFF TO THE NORTHEAST. HOWEVER...SOME SCT -SHRA MAY
LINGER OVER THE SOUTH AS ANOTHER WEAK SHRTWV BRUSHES THE AREA TO THE
SE.
ATTENTION...WILL THEN TURN TO THE DEVELOPING AND UNSEASONABLY STRONG
LOW PRES SYSTEM MOVING OUT OF THE PLAINS. THE SD/NE SHRTWV WILL
SUPPORT A DEEPENING LOW MOVING INTO THE NW CORNER OF IA BY 00Z/WED
AND ERN MN BY 12Z/WED. THE MODELS HAVE TRENDED TOWARD A SLIGHTLY
SLOWER PROGRESSION OF THE LOW AS THE STRONG JET MOVING OUT OF THE
PLAINS HELPS CUT OFF THE MID LEVEL LOW. AN AREA OF STRONG MOISTURE
TRANSPORT AND 305K-310K ISENTROPIC ASCENT WILL BRING AN AREA OF RAIN
THROUGH UPPER MI TONIGHT...MAINLY AFTER MIDNIGHT. HOWEVER...THIS
TRANSIENT BAND IS EXPECTED TO BRING QPF AMOUNTS ONLY IN THE 0.25-
0.50 INCH RANGE OVER THE CNTRL AND ERN CWA. HIGHER AMOUNTS TO AROUND
AN INCH WILL BE POSSIBLE OVER THE FAR WEST CLOSER TO THE STRONGEST
DEEP LAYER QVECTOR CONV AND LIFT WHICH WILL REMAIN TO THE WEST OVER
NRN MN AND WRN LAKE SUPERIOR. WITH MODEST MUCAPE VALUES INTO THE 200-
400 J/KG RANGE ONLY ISOLD TSRA ARE EXPECTED.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 339 AM EDT TUE AUG 18 2015
BY 12Z WED AN INTENSIFYING LOW WILL BE APPROACHING OR OVER THE WRN
CWA. THE 00Z/18 GFS HAS COME INTO GOOD AGREEMENT WITH THE 12Z/17
ECMWF IN DEEPENING THE SFC LOW TO 993-995MB AS THE SYSTEM CLOSES OFF
OVER WRN LAKE SUPERIOR WED. THE NAM . BY 12Z THU THE LOW WILL BE
OCCLUDED N OF LAKE SUPERIOR AND WILL QUICKLY SHUNT N TO HUDSON BAY
BY 00Z FRI.
OVERALL EXPECTATIONS HAVE NOT CHANGED MUCH FROM THE DAY SHIFT MON. A
SURGE OF PRECIP WILL BE EXITING N WED MORNING AHEAD OF THE COLD
FRONT AND THEN DRY SLOT THAT WILL MOVE IN FROM THE SW WED LATE
MORNING/AFTERNOON. COULD SEE SOME STRONG TO POSSIBLY SEVERE STORMS
ALONG THE COLD FRONT AS EFFECTIVE SHEAR IS ENHANCED...BUT OTHERWISE
NOT EXPECTING SEVERE STORMS. AFTER THE DRY SLOT MOVES INTO MAINLY
THE CENTRAL AND ERN CWA...WRAP AROUND PRECIP/MOISTURE WILL MOVE INTO
WRN UPPER MI. THE WRAP AROUND PRECIP WILL SPREAD TO NRN AND WRN
UPPER MI WED NIGHT AND CONTINUE THROUGH MOST OF THU. WED LOOKS WINDY
WITH S-SW WINDS GUSTING TO 25-35 MPH. WINDS THU WILL BE SIMILAR
STRENGTH OF WED...BUT OUT OF THE W.
FRI AND SAT LOOK DRY WITH SW FLOW ALONG AND A SFC HIGH OVER MUCH OF
THE ERN CONUS. HOWEVER...MODELS CONTINUE TO INDICATE THAT ANOTHER
STORM SYSTEM COULD BRING PRECIP SUN INTO MON...BUT DETAILS REMAIN
UNCLEAR AT THIS TIME.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 125 AM EDT TUE AUG 18 2015
ALTHOUGH SOME -SHRA MAY IMPACT IWD AND PERHAPS CMX LATER...THERE
SHOULD BE ENUF LLVL DRY AIR TO MAINTAIN VFR CONDITIONS. AT SAW...AN
UPSLOPE NE FLOW CLOSER TO STALLED FNT JUST TO THE SE OF UPR MI IN
THE PRESENCE OF NOCTURNAL COOLING WL RESULT IN A DEVELOPMENT OF MVFR
CONDITIONS FOR A TIME THIS MRNG BEFORE DAYTIME HEATING BRINGS A
RETURN OF VFR WX FOR A SHORT TIME. LOWER MVFR CIGS WL RETURN TO THAT
SITE ALONG WITH THE CHC FOR SOME -SHRA LATE IN THE DAY AS THE
STALLED FNT BEGINS MOVING TO THE N. SOME -SHRA WL RETURN TO IWD AS
WELL...BUT DOWNSLOPE NATURE OF THE LLVL WIND THERE SHOULD MAINTAIN
VFR CONDITIONS AT THE ONSET OF ANY PCPN. A STRENGTHENING ESE FLOW
AHEAD OF DEEPENING LO PRES IN THE PLAINS WL BRING A RETURN OF MORE
WDSPRD -RA/MVFR CONDITIONS IN THE EVNG. IFR CONDITIONS WL BE LIKELY
AFTER THE END OF THIS CURRENT TAF PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 443 PM EDT MON AUG 17 2015
HIGH PRES STRETCHING FROM SOUTHERN MANITOBA THROUGH JAMES BAY WILL
EXTEND A RIDGE INTO THE UPPER LAKES THRU TUE MORNING...RESULTING IN
LIGHT WINDS UNDER 15KT ACROSS LAKE SUPERIOR THRU TUE MORNING.
THEN...AS LOW PRES ORGANIZES AND STRENGTHENS OVER THE PLAINS
TUE...NE WINDS WILL BEGIN TO RAMP UP...ESPECIALLY OVER WRN LAKE
SUPERIOR WHERE GUSTS SHOULD REACH 25-30KT LATE AFTN/EARLY EVENING.
THIS LOW WILL BECOME UNSEASONABLY DEEP FOR AUG AS IT LIFTS ACROSS
FAR WRN LAKE SUPERIOR WED AFTN. 20-30KT WINDS ARE EXPECTED OVER MUCH
OF THE LAKE TUE NIGHT INTO WED. MAY SEE GALE FORCE GUSTS OVER FAR
WRN LAKE SUPERIOR IN THE NE WINDS AHEAD OF THE LOW TUE NIGHT AND
THEN IN THE WESTERLY WINDS ACROSS MAINLY CENTRAL LAKE SUPERIOR ON
THU AS THE LOW LIFTS N OF THE AREA. WINDS WILL DIMINISH TO UNDER
20KT FRI...AND THEN BEGIN TO INCREASE AGAIN ON SAT AHEAD OF THE NEXT
COLD FRONT MOVING OUT ACROSS THE PLAINS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...TITUS
AVIATION...KC
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
340 AM EDT TUE AUG 18 2015
.UPDATE...
ISSUED AT 848 PM EDT MON AUG 17 2015
ADDED SOME ISOLD SHOWERS TO THE FCST FOR WRN UPR MI OVERNGT TO
ACCOUNT FOR AREA OF SHOWERS MOVING SLOWLY NE THRU NW WI AHEAD OF
DISTURBANCE IN SW MN AND UNDER COOLING CLD TOPS. POTENT SHRTWV
DIGGING INTO THE NRN PLAINS WL LIKELY CAUSE THE UPR FLOW TO BACK ENUF
TO LIFT THESE SHOWERS INTO THE WRN CWA. ONLY THE LATEST RAPID REFRESH
MODEL HAS A GOOD HANDLE ON THE LOCATION OF THE PCPN AT PRESENT TIME.
THIS MODEL SHOWS THESE SHOWERS SPREADING INTO WRN UPR MI AFTER MIDNGT
DESPITE SOME DRIER LLVL AIR THAT WL RESTRICT THE COVERAGE/INTENSITY.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 443 PM EDT MON AUG 17 2015
WATER VAPOR IMAGERY AND RAP ANALYSIS SHOW A BROAD TROF EXTENDING S
INTO THE NRN ROCKIES NRN PLAINS. POTENT LOOKING SHORTWAVE OVER SW MT
WILL GENERATE AN UNUSUALLY STRONG SFC LOW FOR AUG THAT WILL MOVE
ACROSS THE UPPER MISSISSIPPI VALLEY/UPPER GREAT LAKES TUE NIGHT/WED.
SYSTEM ON WATER VAPOR IMAGERY LOOKS STRONGER THAN INDICATED BY
MODELS RIGHT NOW...SO IT WILL BE INTERESTING TO SEE HOW THIS SYSTEM
EVOLVES. TO THE E AND AT THE SFC...COLD FRONT HAS DRIFTED S OF UPPER
MI. WEAKER SHORTWAVES AND RIGHT ENTRANCE OF UPPER JET EXTENDING FROM
NRN MN TO NRN QUEBEC ARE AIDING SHRA/TSTMS FROM IA/SRN MN ENE TO ERN
UPPER MI AND LWR MI. PER LATEST SPC ANALYSIS NRN EDGE OF INSTABILITY
(MLCAPES EXCEEDING 100J/KG) ONLY EXTENDS AS FAR N AS NEAR KMNM AND
THEN E ACROSS NRN LAKE MI. THUS...NO THUNDER HAS BEEN NOTED IN UPPER
MI THIS AFTN.
RIGHT ENTRANCE OF A LESS WELL-DEFINED WITH TIME UPPER JET WILL POSE
SOME RISK FOR GENERATING -SHRA AT TIMES TONIGHT TO THE N OF THE COLD
FRONT WHICH WILL BECOME NEARLY STATIONARY. THERE MAY BE A SUBTLE
SHORTWAVE UPSTREAM AS WELL WHICH COULD AID -SHRA DEVELOPMENT FARTHER
N PER ECWMF...BUT STAYED CLOSE TO THE MULTI-MODEL CONSENSUS IN
CARRYING SCHC POPS FOR AT LEAST SOME PORTION OF THE NIGHT OVER
ROUGHLY THE SE HALF OF THE FCST AREA. CHC POPS WERE CONFINED TO THE
FAR SCNTRL...AND ALSO SE CLOSE TO LAKE MI THIS EVENING. NOT
EXPECTING ANY TSTMS. MAY SEE SOME PATCHY FOG OVERNIGHT.
ON TUE...SFC LOW PRES ORGANIZES OVER THE PLAINS AND REACHES NW IA
LATE IN THE DAY IN RESPONSE TO THE STRONG SHORTWAVE MOVING OUT OVER
THE PLAINS. STRENGTHENING DEEP LAYER FORCING AND STRONG MOISTURE
TRANSPORT AHEAD OF FEATURE WILL SPREAD OVER MN AND THEN TOWARD NW
WI/WRN LAKE SUPERIOR/WRN UPPER MI LATE IN THE AFTN...RESULTING IN AN
INCREASING AREA OF MDT/HVY RAIN AND EMBEDDED THUNDER ORGANIZING TO
THE W AND SW. LOOKS LIKE MUCH OF THIS PCPN WILL HOLD OFF UNTIL TUE
NIGHT. AS FRONT TO THE S BEGINS TO MOVE BACK TO THE N AS A WARM
FRONT...PROBABLY CAN`T RULE OUT A FEW -SHRA DEVELOPING N OF THE
FRONT AS WAA BEGINS...BUT AT LEAST RIGHT NOW...POTENTIAL APPEARS
QUITE LOW. ONLY SCHC WILL BE UTILIZED EXCEPT FOR THE W IN THE AFTN
WHERE POPS WILL INCREASE THRU THE CHC CATEGORY.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 339 AM EDT TUE AUG 18 2015
BY 12Z WED AN INTENSIFYING LOW WILL BE APPROACHING OR OVER THE WRN
CWA. THE 00Z/18 GFS HAS COME INTO GOOD AGREEMENT WITH THE 12Z/17
ECMWF IN DEEPENING THE SFC LOW TO 993-995MB AS THE SYSTEM CLOSES OFF
OVER WRN LAKE SUPERIOR WED. THE NAM . BY 12Z THU THE LOW WILL BE
OCCLUDED N OF LAKE SUPERIOR AND WILL QUICKLY SHUNT N TO HUDSON BAY
BY 00Z FRI.
OVERALL EXPECTATIONS HAVE NOT CHANGED MUCH FROM THE DAY SHIFT MON. A
SURGE OF PRECIP WILL BE EXITING N WED MORNING AHEAD OF THE COLD
FRONT AND THEN DRY SLOT THAT WILL MOVE IN FROM THE SW WED LATE
MORNING/AFTERNOON. COULD SEE SOME STRONG TO POSSIBLY SEVERE STORMS
ALONG THE COLD FRONT AS EFFECTIVE SHEAR IS ENHANCED...BUT OTHERWISE
NOT EXPECTING SEVERE STORMS. AFTER THE DRY SLOT MOVES INTO MAINLY
THE CENTRAL AND ERN CWA...WRAP AROUND PRECIP/MOISTURE WILL MOVE INTO
WRN UPPER MI. THE WRAP AROUND PRECIP WILL SPREAD TO NRN AND WRN
UPPER MI WED NIGHT AND CONTINUE THROUGH MOST OF THU. WED LOOKS WINDY
WITH S-SW WINDS GUSTING TO 25-35 MPH. WINDS THU WILL BE SIMILAR
STRENGTH OF WED...BUT OUT OF THE W.
FRI AND SAT LOOK DRY WITH SW FLOW ALONG AND A SFC HIGH OVER MUCH OF
THE ERN CONUS. HOWEVER...MODELS CONTINUE TO INDICATE THAT ANOTHER
STORM SYSTEM COULD BRING PRECIP SUN INTO MON...BUT DETAILS REMAIN
UNCLEAR AT THIS TIME.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 125 AM EDT TUE AUG 18 2015
ALTHOUGH SOME -SHRA MAY IMPACT IWD AND PERHAPS CMX LATER...THERE
SHOULD BE ENUF LLVL DRY AIR TO MAINTAIN VFR CONDITIONS. AT SAW...AN
UPSLOPE NE FLOW CLOSER TO STALLED FNT JUST TO THE SE OF UPR MI IN
THE PRESENCE OF NOCTURNAL COOLING WL RESULT IN A DEVELOPMENT OF MVFR
CONDITIONS FOR A TIME THIS MRNG BEFORE DAYTIME HEATING BRINGS A
RETURN OF VFR WX FOR A SHORT TIME. LOWER MVFR CIGS WL RETURN TO THAT
SITE ALONG WITH THE CHC FOR SOME -SHRA LATE IN THE DAY AS THE
STALLED FNT BEGINS MOVING TO THE N. SOME -SHRA WL RETURN TO IWD AS
WELL...BUT DOWNSLOPE NATURE OF THE LLVL WIND THERE SHOULD MAINTAIN
VFR CONDITIONS AT THE ONSET OF ANY PCPN. A STRENGTHENING ESE FLOW
AHEAD OF DEEPENING LO PRES IN THE PLAINS WL BRING A RETURN OF MORE
WDSPRD -RA/MVFR CONDITIONS IN THE EVNG. IFR CONDITIONS WL BE LIKELY
AFTER THE END OF THIS CURRENT TAF PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 443 PM EDT MON AUG 17 2015
HIGH PRES STRETCHING FROM SOUTHERN MANITOBA THROUGH JAMES BAY WILL
EXTEND A RIDGE INTO THE UPPER LAKES THRU TUE MORNING...RESULTING IN
LIGHT WINDS UNDER 15KT ACROSS LAKE SUPERIOR THRU TUE MORNING.
THEN...AS LOW PRES ORGANIZES AND STRENGTHENS OVER THE PLAINS
TUE...NE WINDS WILL BEGIN TO RAMP UP...ESPECIALLY OVER WRN LAKE
SUPERIOR WHERE GUSTS SHOULD REACH 25-30KT LATE AFTN/EARLY EVENING.
THIS LOW WILL BECOME UNSEASONABLY DEEP FOR AUG AS IT LIFTS ACROSS
FAR WRN LAKE SUPERIOR WED AFTN. 20-30KT WINDS ARE EXPECTED OVER MUCH
OF THE LAKE TUE NIGHT INTO WED. MAY SEE GALE FORCE GUSTS OVER FAR
WRN LAKE SUPERIOR IN THE NE WINDS AHEAD OF THE LOW TUE NIGHT AND
THEN IN THE WESTERLY WINDS ACROSS MAINLY CENTRAL LAKE SUPERIOR ON
THU AS THE LOW LIFTS N OF THE AREA. WINDS WILL DIMINISH TO UNDER
20KT FRI...AND THEN BEGIN TO INCREASE AGAIN ON SAT AHEAD OF THE NEXT
COLD FRONT MOVING OUT ACROSS THE PLAINS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KC
SHORT TERM...ROLFSON
LONG TERM...TITUS
AVIATION...KC
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS GAYLORD MI
328 AM EDT TUE AUG 18 2015
.NEAR TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 328 AM EDT TUE AUG 18 2015
HIGH IMPACT WEATHER POTENTIAL...NON-SEVERE THUNDERSTORMS TODAY AND
TONIGHT.
DIFFUSE COLD FRONT RESTS ROUGHLY FROM OSC TO MBL. THIS FRONT IS
STALLING OUT...AS LEE CYCLOGENESIS GETS UNDERWAY IN THE CENTRAL
HIGH PLAINS. SOME SHRA ARE SEEN OVER CENTRAL/NORTHERN LAKE MI AND
SURROUNDING AREAS. A FEW SHRA HAVE ALSO RECENTLY DEVELOPED JUST SW
OF LAN. NO THUNDER LEFT IN OUR NECK OF THE WOODS. THE FRONT WILL
WOBBLE ACROSS CENTRAL/NORTHERN LOWER MI OVER THE NEXT 24
HOURS...AS HEATING/CONVECTION/SOUTHERLY FLOW WAXES AND WANES.
PRECIP TRENDS ARE THE MAIN CONCERN.
TODAY...A POTENT SHORTWAVE WILL DIG FROM THE NORTHERN TO CENTRAL
HIGH PLAINS TODAY. IN RESPONSE...PRESSURES WILL RAPIDLY FALL IN THE
CENTRAL PLAINS. BY MID-EVENING...A SUB-1000MB LOW WILL BE MOVING
INTO NW IOWA. SOUTHERLY 1000-850MB FLOW INTO LOWER MI WILL INCREASE
TO SOME DEGREE...THOUGH THE TIGHTEST PRESSURE GRADIENT WILL REMAIN
TO OUR WEST THRU 00Z. STILL...THAT AND DIURNAL HEATING/MIXING WILL
TEND TO PUSH THE FRONT NORTH. HOWEVER...PRECIP AND SUBSEQUENT COLD-
POOL GENERATION NORTH OF THE FRONT WILL WORK TO SUPPRESS ANY
NORTHWARD MOVEMENT. THE NAM WANTS TO PUSH THE FRONT QUICKLY NORTH IN
THE 1ST HALF OF THE DAY...AN INTERNALLY INCONSISTENT APPROACH SINCE
IT IS ALSO AMONG THE WETTEST SOLUTIONS NORTH OF THE FRONT THIS
MORNING. THE RAP OFFERS A BETTER ALTERNATIVE IN THE NEAR-TERM...WITH
THE FRONT REACHING A MANTON-HARRISVILLE LINE BY MIDDAY...BEFORE
GETTING ABRUPTLY SHOVED SOUTHWARD AGAIN AS PRECIP BECOMES MORE
EXPANSIVE.
SPEAKING OF WHICH...THERE ARE A PAIR OF SHORTWAVES MOVING EAST
TOWARD THE LAKES REGION EARLY THIS MORNING...ONE IN W CENTRAL WI AND
THE 2ND IN NW IL. THESE WILL BOTH ACT TO PROVIDE FORCING FOR ASCENT
JUST AFTER SUNRISE IN WESTERN SECTIONS. HOWEVER...AT THIS TIME OF
DAY NEITHER HAS MUCH IN THE WAY OF INSTABILITY TO WORK WITH. NOTE
THAT ACTIVITY MOVING ENE OUT OF CHICAGO IS FIZZLING RAPIDLY OVER
SOUTHERN LAKE MI. GENERALLY THINK THAT...THRU 10AM...THE MAIN PRECIP
CHANCES WILL BE WEST OF TVC/CAD...IN EASTERN UPPER MI...AND IN
PARTS OF NE LOWER (IF DOWNSTATE ACTIVITY DEVELOPS NE-WARD AS
AGGRESSIVELY AS RECENT RAP RUNS SUGGEST).
HOWEVER...WE HAVE PLENTY OF MOISTURE (PWATS 1.5-1.7) AND SOME
FORCING FOR ASCENT AVAILABLE. SO IT WILL TAKE VERY LITTLE HEATING
(EVEN WITH CONSIDERABLE CLOUD COVER) TO PRIME THE AIRMASS FOR
CONVECTION. THIS IS ESPECIALLY THE CASE GIVEN THAT (AS OPPOSED TO
YESTERDAY) WE ACTUALLY HAVE CROSS-FRONTAL 1000-850MB FLOW.
ANTICIPATE SHRA WILL RAPIDLY EXPAND IN COVERAGE OVER NW LOWER MI
BETWEEN 10AM AND NOON. FURTHER EXPANSION ACROSS THE BULK OF NORTHERN
LOWER WILL OCCUR AS ACTIVITY CONTINUES TO PERCOLATE THRU THE
AFTERNOON. SOME OF THIS ACTIVITY WILL LEAK INTO EASTERN UPPER...BUT
THAT FAR NORTH OF THE WARM FRONT SUSPECT COVERAGE THERE WILL BE LESS
THAN THE NAM/GFS ARGUE. CONVECTION WILL BE QUICK TO TRIGGER...SO WE
WON/T REALLY GET THE CHANCE TO BUILD UP MUCH IN THE WAY OF CAPE.
MLCAPES SHOULD STAY LESS THAN 500J/KG. THIS WILL KEEP PRECIP MAINLY
AS SHRA...WITH A FEW EMBEDDED TSRA...AND NO SVR THREAT. LOCALIZED
RAINFALL AMOUNTS OF A QUARTER TO HALF AN INCH WILL BE SEEN.
WILL BE A MUGGY DAY...BUT TEMPS WILL BE SHARPLY LIMITED BY
CLOUDS/PRECIP. HIGHS WILL BE MAINLY IN THE 70S...PEAKING UP CLOSE TO
80F IN A FEW SPOTS.
TONIGHT...PRIMARY 500MB CIRCULATION CLOSES OFF AND DEEPENS AS IT
MOVES FROM EASTERN SD TO SOUTHERN MN. THE CORRESPONDING SURFACE LOW
WILL DEEPEN TO 994MB AS IT MOVES TO THE MN/WI BORDER. IN ADVANCE OF
THIS DEVELOPING CYCLONE...SOUTHERLY 850MB WINDS WILL INCREASE TO 20-
30KT. THIS WILL PUSH THE SURFACE WARM FRONT MORE EMPHATICALLY
NORTHWARD TOWARD FAR NORTHERN LOWER OR THE STRAITS REGION. CHANCES
FOR PRECIP WILL DECREASE BEHIND THE FRONT. SHRA COVERAGE WILL BE
CONSIDERABLE ACROSS THE FORECAST AREA IN THE EVENING...BUT POPS WILL
DECREASE (THOUGH NOT DISAPPEAR) SOUTH OF M-32 OVERNIGHT. IN
ADDITION...IT IS LIKELY OVERNIGHT THAT ONE OR MORE MCS/S WILL BE
MOVING EAST IN THE WARM SECTOR INTO THE SW LAKES REGION. DON/T THINK
THAT THESE WILL HOLD TOGETHER AND REACH SW SECTIONS TOWARD
DAYBREAK...BUT IT/S NOT IMPOSSIBLE. THAT/S OUR VERY LOW-END SHOT AT
ANYTHING SVR...OTHERWISE MLCAPE IS TOO LIMITED.
STILL MUGGY AND A VERY WARM NIGHT...WITH LOWS IN THE MID 60S TO
AROUND 70F.
&&
.SHORT TERM...(WEDNESDAY THROUGH THURSDAY NIGHT)
ISSUED AT 328 AM EDT TUE AUG 18 2015
LOW PRESSURE EMERGES OUT OF THE CENTRAL PLAINS TODAY THEN HEADS
NORTHEAST INTO THE NORTHERN MISSISSIPPI VALLEY WHILE DEEPENING. THE
IMPACTS FROM THIS SYSTEM WILL BE THE FOCUS OF THE FORECAST WITH THE
MAIN CHALLENGE BEING THE POTENTIAL FOR SEVERE STORMS WEDNESDAY.
WEDNESDAY...THE TRACK OF A NEGATIVELY TILTED TROUGH AND ASSOCIATED
AREA OF DEEPENING LOW PRESSURE TO OUR NORTHWEST IS EXPECTED TO LEAD
TO A SOLID AREA OF SHOWERS ACROSS EASTERN UPPER AND FAR NORTHWEST
LOWER WEDNESDAY WITH SLIGHTLY LESSER BUT MORE CONVECTIVE
SHOWER/STORM COVERAGE ACROSS SOUTHEAST ZONES. THERE IS A THREAT FOR
SEVERE STORMS...MAINLY BECAUSE OF STRONGER WINDS ALOFT (NAM 0-6KM
BULK SHEAR 30 TO 40 KNOTS WITH THE MORE BULLISH GFS A ROBUST 50 TO
55 KNOTS!). IN ADDITION TO THE STRONG WINDS ALOFT NORTHEAST LOWER
MAY ALSO GET INTO HEALTHY AMOUNTS OF INSTABILITY IF THE SUN IS ABLE
TO BREAK OUT IN THE DRY SLOT. SO NOT SURPRISINGLY...SPC HAS JUST
PLACED ALL OF NORTHERN LOWER IN A SLIGHT RISK FOR WIND AND/OR HAIL.
MODELS CONTINUE TO DIFFER ON THE FINER DETAILS OF THIS SYSTEM
INCLUDING TIMING AND STRENGTH (THOUGH BOTH THE ECMWF AND GFS ARE
TRENDING STRONGER) SO STAY TUNED FOR FURTHER UPDATES AS THIS
POSSIBLE EVENT GETS A LITTLE CLOSER. A SYSTEM THIS DEEP THIS TIME OF
THE YEAR IS A BIT UNUSUAL SO THINGS HAVE THE POTENTIAL TO GET
INTERESTING. HIGHS RANGING FROM THE MUGGY UPPER 70S NORTH TO PERHAPS
THE TOASTY UPPER 80S SOUTHEAST ZONES.
WEDNESDAY NIGHT...A FEW MORE SHOWERS (AND THUNDERSTORMS EAST) ARE
LIKELY AS THE COLD FRONT ASSOCIATED WITH THE LOW PRESSURE SYSTEM
MOVES ACROSS THE REGION (ACTUALLY IT MAY BE MORE OF AN OCCLUDED
FRONT AT THAT POINT). LOWS RANGING FROM THE UPPER 50S TO MIDDLE 60S.
THURSDAY...WRAP AROUND SHOWERS ARE POSSIBLE ACROSS EASTERN UPPER AND
FAR NORTHERN LOWER...ESPECIALLY IN THE MORNING. COOLER WITH HIGHS
ONLY IN THE UPPER 60S AND LOWER 70S.
&&
.LONG TERM...(FRIDAY THROUGH MONDAY)
ISSUED AT 328 AM EDT TUE AUG 18 2015
HIGH PRESSURE BUILDS IN FRIDAY WHICH SHOULD HOLD ON THROUGH SATURDAY
NIGHT YIELDING WARMER AND DRIER CONDITIONS. ANOTHER AREA OF LOW
PRESSURE TRACKING BY TO OUR NORTHWEST WILL THEN BRING MORE CHANCES
FOR SHOWERS AND THUNDERSTORMS SUNDAY...WITH WRAP AROUND DRIVEN
SHOWERS POSSIBLY LINGERING INTO MONDAY (MODELS ARE NOT IN AGREEMENT
HERE BUT PLENTY OF TIME TO MAKE ADJUSTMENTS). HIGHS BACK IN THE
UPPER 70S AND LOWER 80S FRIDAY THROUGH SUNDAY. COOLER AGAIN FOR
MONDAY WITH HIGHS IN THE UPPER 60S AND LOWER 70S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 143 AM EDT TUE AUG 18 2015
VARIABLE CONDITIONS THRU THE TAF PERIOD.
STALLED COLD FRONT IS LAID OUT ALONG THE M-55 CORRIDOR. THIS FRONT
WILL WOBBLE ACROSS CENTRAL AND NORTHERN LOWER MI TODAY AND
TONIGHT. CONSIDERABLE SHRA AND A FEW TSRA WILL BE SEEN NORTH OF
THE FRONT...ESPECIALLY FROM LATE MORNING TODAY THRU TONIGHT. THESE
AREAS WILL ALSO BE PRONE TO LOWERED CIGS/VSBYS...ESPECIALLY DURING
THE NIGHTS/MORNINGS. PRESENTLY APN IS LIFR WHILE OTHER SITES ARE
VFR. EXPECTED ALL SITES TO HAVE SOME RESTRICTIONS BY
DAYBREAK...SEE SOME DEGREE OF IMPROVEMENT DURING THE DAY...AND
THEN WORSEN A BIT AGAIN TOWARD MIDNIGHT TONIGHT.
WINDS WILL BE LIGHT SOUTHERLY TO EASTERLY.
&&
.MARINE...
ISSUED AT 328 AM EDT TUE AUG 18 2015
A STALLED FRONT WILL WOBBLE ACROSS CENTRAL LOWER MI TODAY...BEFORE
MOVING NORTH TONIGHT AS A WARM FRONT. SE-ERLY WINDS WILL BE LIGHT
THRU THIS EVENING...BUT INCREASE OVERNIGHT. SMALL CRAFT
ADVISORIES WILL LIKELY BE NEEDED ON SOME WATERS BY WEDNESDAY
AFTERNOON. A STRONG COLD FRONT WILL CROSS THE REGION LATE
WEDNESDAY...WITH STRONG TO POTENTIALLY SVR THUNDERSTORMS.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
NEAR TERM...JAZ
SHORT TERM...SULLIVAN
LONG TERM...SULLIVAN
AVIATION...JAZ
MARINE...JAZ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
126 AM EDT TUE AUG 18 2015
.UPDATE...
ISSUED AT 848 PM EDT MON AUG 17 2015
ADDED SOME ISOLD SHOWERS TO THE FCST FOR WRN UPR MI OVERNGT TO
ACCOUNT FOR AREA OF SHOWERS MOVING SLOWLY NE THRU NW WI AHEAD OF
DISTURBANCE IN SW MN AND UNDER COOLING CLD TOPS. POTENT SHRTWV
DIGGING INTO THE NRN PLAINS WL LIKELY CAUSE THE UPR FLOW TO BACK ENUF
TO LIFT THESE SHOWERS INTO THE WRN CWA. ONLY THE LATEST RAPID REFRESH
MODEL HAS A GOOD HANDLE ON THE LOCATION OF THE PCPN AT PRESENT TIME.
THIS MODEL SHOWS THESE SHOWERS SPREADING INTO WRN UPR MI AFTER MIDNGT
DESPITE SOME DRIER LLVL AIR THAT WL RESTRICT THE COVERAGE/INTENSITY.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 443 PM EDT MON AUG 17 2015
WATER VAPOR IMAGERY AND RAP ANALYSIS SHOW A BROAD TROF EXTENDING S
INTO THE NRN ROCKIES NRN PLAINS. POTENT LOOKING SHORTWAVE OVER SW MT
WILL GENERATE AN UNUSUALLY STRONG SFC LOW FOR AUG THAT WILL MOVE
ACROSS THE UPPER MISSISSIPPI VALLEY/UPPER GREAT LAKES TUE NIGHT/WED.
SYSTEM ON WATER VAPOR IMAGERY LOOKS STRONGER THAN INDICATED BY
MODELS RIGHT NOW...SO IT WILL BE INTERESTING TO SEE HOW THIS SYSTEM
EVOLVES. TO THE E AND AT THE SFC...COLD FRONT HAS DRIFTED S OF UPPER
MI. WEAKER SHORTWAVES AND RIGHT ENTRANCE OF UPPER JET EXTENDING FROM
NRN MN TO NRN QUEBEC ARE AIDING SHRA/TSTMS FROM IA/SRN MN ENE TO ERN
UPPER MI AND LWR MI. PER LATEST SPC ANALYSIS NRN EDGE OF INSTABILITY
(MLCAPES EXCEEDING 100J/KG) ONLY EXTENDS AS FAR N AS NEAR KMNM AND
THEN E ACROSS NRN LAKE MI. THUS...NO THUNDER HAS BEEN NOTED IN UPPER
MI THIS AFTN.
RIGHT ENTRANCE OF A LESS WELL-DEFINED WITH TIME UPPER JET WILL POSE
SOME RISK FOR GENERATING -SHRA AT TIMES TONIGHT TO THE N OF THE COLD
FRONT WHICH WILL BECOME NEARLY STATIONARY. THERE MAY BE A SUBTLE
SHORTWAVE UPSTREAM AS WELL WHICH COULD AID -SHRA DEVELOPMENT FARTHER
N PER ECWMF...BUT STAYED CLOSE TO THE MULTI-MODEL CONSENSUS IN
CARRYING SCHC POPS FOR AT LEAST SOME PORTION OF THE NIGHT OVER
ROUGHLY THE SE HALF OF THE FCST AREA. CHC POPS WERE CONFINED TO THE
FAR SCNTRL...AND ALSO SE CLOSE TO LAKE MI THIS EVENING. NOT
EXPECTING ANY TSTMS. MAY SEE SOME PATCHY FOG OVERNIGHT.
ON TUE...SFC LOW PRES ORGANIZES OVER THE PLAINS AND REACHES NW IA
LATE IN THE DAY IN RESPONSE TO THE STRONG SHORTWAVE MOVING OUT OVER
THE PLAINS. STRENGTHENING DEEP LAYER FORCING AND STRONG MOISTURE
TRANSPORT AHEAD OF FEATURE WILL SPREAD OVER MN AND THEN TOWARD NW
WI/WRN LAKE SUPERIOR/WRN UPPER MI LATE IN THE AFTN...RESULTING IN AN
INCREASING AREA OF MDT/HVY RAIN AND EMBEDDED THUNDER ORGANIZING TO
THE W AND SW. LOOKS LIKE MUCH OF THIS PCPN WILL HOLD OFF UNTIL TUE
NIGHT. AS FRONT TO THE S BEGINS TO MOVE BACK TO THE N AS A WARM
FRONT...PROBABLY CAN`T RULE OUT A FEW -SHRA DEVELOPING N OF THE
FRONT AS WAA BEGINS...BUT AT LEAST RIGHT NOW...POTENTIAL APPEARS
QUITE LOW. ONLY SCHC WILL BE UTILIZED EXCEPT FOR THE W IN THE AFTN
WHERE POPS WILL INCREASE THRU THE CHC CATEGORY.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 332 PM EDT MON AUG 17 2015
A LOW INTENSIFYING ALONG THE MINNESOTA AND IOWA BORDER AT THE START
OF THE PERIOD WILL BRING UNSETTLED WEATHER FOR THE UPPER GREAT
LAKES REGION THROUGH THE FIRST HALF OF THE LONG TERM FORECAST. THIS
LOW WILL BE AROUND 998MB AND WILL BE LIFTING TO THE NORTH TUESDAY
NIGHT INTO WEDNESDAY (WHILE STRENGTHENING TO 993MB) IN RESPONSE TO
A SHORTWAVE ROUNDING THE BASE OF THE UPPER TROUGH IN THE NORTHERN
PLAINS. THERE ARE SOME DIFFERENCES IN THE MODELS ON HOW FAST THIS
LOW (ANOMALOUS FOR MID-LATE AUGUST) WILL MOVE NORTH THROUGH THE
DULUTH AREA AND ACROSS WESTERN LAKE SUPERIOR ON WEDNESDAY...BUT WITH
THE RECENT TRENDS HEADING TOWARDS A SLOWER DEPARTURE FROM LAKE
SUPERIOR...WILL FOLLOW THAT IDEA IN THE FORECAST.
EXPECT A FEW WAVES OF PRECIPITATION TO MOVE THROUGH THE U.P. WITH
THIS LOW...BUT UNFORTUNATELY THE TRACK WILL NOT PROMOTE A
MUCH NEEDED WIDESPREAD AND SOAKING RAIN FOR MOST OF THE AREA. THE
FIRST WAVE WILL ARRIVE LATE TOMORROW AFTERNOON AND INTO TOMORROW
NIGHT AS BROAD MID LEVEL WARM AIR ADVECTION SWEEPS NORTH ACROSS THE
AREA. THE BEST ASCENT WILL BE TO THE WEST-NORTHWEST OF THE AREA AND
TOWARDS THE MINNESOTA ARROWHEAD...BUT THE WESTERN U.P. COULD BE
BRUSHED BY SOME OF THE STRONGER AREAS OF RAIN. OTHERWISE...EXPECT
RAINFALL AMOUNTS TO SLOWLY DIMINISH FROM AROUND AN INCH OVER THE FAR
WEST TO A HALF AN INCH OR LESS TO THE EAST OF NEWBERRY.
THE NEXT WAVE WILL PUSH NORTH-NORTHEAST THROUGH THE CWA ON
WEDNESDAY MORNING AND PRODUCE AN AREA OF SCATTERED/NUMEROUS SHOWERS
AND MAYBE A FEW THUNDERSTORMS AS IT MOVES THROUGH THE AREA. WILL
SHOW A PERIOD OF THUNDER CHANCES ALONG THAT FRONT AS IT MOVES
THROUGH...TIED TO THE LOWER SHOWALTER VALUES AND MUCAPE VALUES
RISING BETWEEN 500-750 J/KG RIGHT ALONG THE FRONT. EFFECTIVE SHEAR
VALUES LOOK TO BE FAIRLY LOW...SO THAT SHOULD ELIMINATE MUCH OF THE
SEVERE THREAT...EXCEPT FOR AREAS RIGHT ALONG THE COLD FRONT WHICH
WILL TRY TO PUSH EFFECTIVE SHEAR VALUES UP TOWARDS 30KTS. AS THIS
FRONT MOVES NORTH THROUGH THE DAY AND THE DRY SLOT MOVES OVER THE
AREA ALOFT...HAVE TRENDED POPS DOWN OVER THE CENTRAL AND EAST
THROUGH THE DAY...WITH ONLY SLIGHT CHANCES IN THE AFTERNOON
(ALTHOUGH THAT MAY BE TOO HIGH). WRAP AROUND RAIN WILL THEN ARRIVE
OVER THE WEST LATE WEDNESDAY AFTERNOON AND CONTINUE INTO WEDNESDAY
NIGHT. EXPECT THE SCATTERED/NUMEROUS SHOWERS TO STAY MORE OVER THE
WESTERN U.P. BUT DID SPREAD CHANCES EAST OVERNIGHT INTO THURSDAY FOR
MUCH OF THE REST OF THE U.P. WINDS WILL ALSO BE ON THE INCREASE
LATE WEDNESDAY NIGHT INTO THURSDAY MORNING BEHIND THE LOW DUE TO
THE COMBINED PRESSURE RISE AND STEEPENING LOW LEVEL LAPSE RATES
TOWARDS 8-9 C/KM BETWEEN THE SURFACE AND 900MB. THAT WILL LIKELY
PRODUCE GUSTS TO 30KTS OVER WESTERN/CENTRAL LAKE SUPERIOR AND
20-30KTS OVER MOST LAND AREAS.
CONDITIONS WILL IMPROVE THURSDAY NIGHT AS A HIGH PRESSURE RIDGE
BUILDS INTO THE AREA. THIS WILL BRING DECREASING CLOUDS AND WINDS
THROUGH THE NIGHT AND SHOULD LEAD TO A NICE DAY ACROSS THE AREA ON
FRIDAY. THE SUNSHINE WILL BRING HIGHS BACK UP TO NORMAL OR SLIGHTLY
ABOVE NORMAL VALUES ON FRIDAY AND EXPECT TEMPERATURES A TOUCH
WARMER ON SATURDAY (AROUND 80) WITH THE SOUTHERLY FLOW.
ANOTHER STRONG UPPER TROUGH WILL MOVE INTO THE NORTHERN PLAINS ON
SATURDAY AND MOVE THROUGH THE AREA SUNDAY INTO SUNDAY NIGHT. WILL
CONTINUE TO SHOW HIGH CHANCE AND LOW END LIKELY POPS AS THAT MOVES
THROUGH THE AREA BEFORE SLOWLY DEPARTING ON MONDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 125 AM EDT TUE AUG 18 2015
ALTHOUGH SOME -SHRA MAY IMPACT IWD AND PERHAPS CMX LATER...THERE
SHOULD BE ENUF LLVL DRY AIR TO MAINTAIN VFR CONDITIONS. AT SAW...AN
UPSLOPE NE FLOW CLOSER TO STALLED FNT JUST TO THE SE OF UPR MI IN
THE PRESENCE OF NOCTURNAL COOLING WL RESULT IN A DEVELOPMENT OF MVFR
CONDITIONS FOR A TIME THIS MRNG BEFORE DAYTIME HEATING BRINGS A
RETURN OF VFR WX FOR A SHORT TIME. LOWER MVFR CIGS WL RETURN TO THAT
SITE ALONG WITH THE CHC FOR SOME -SHRA LATE IN THE DAY AS THE
STALLED FNT BEGINS MOVING TO THE N. SOME -SHRA WL RETURN TO IWD AS
WELL...BUT DOWNSLOPE NATURE OF THE LLVL WIND THERE SHOULD MAINTAIN
VFR CONDITIONS AT THE ONSET OF ANY PCPN. A STRENGTHENING ESE FLOW
AHEAD OF DEEPENING LO PRES IN THE PLAINS WL BRING A RETURN OF MORE
WDSPRD -RA/MVFR CONDITIONS IN THE EVNG. IFR CONDITIONS WL BE LIKELY
AFTER THE END OF THIS CURRENT TAF PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 443 PM EDT MON AUG 17 2015
HIGH PRES STRETCHING FROM SOUTHERN MANITOBA THROUGH JAMES BAY WILL
EXTEND A RIDGE INTO THE UPPER LAKES THRU TUE MORNING...RESULTING IN
LIGHT WINDS UNDER 15KT ACROSS LAKE SUPERIOR THRU TUE MORNING.
THEN...AS LOW PRES ORGANIZES AND STRENGTHENS OVER THE PLAINS
TUE...NE WINDS WILL BEGIN TO RAMP UP...ESPECIALLY OVER WRN LAKE
SUPERIOR WHERE GUSTS SHOULD REACH 25-30KT LATE AFTN/EARLY EVENING.
THIS LOW WILL BECOME UNSEASONABLY DEEP FOR AUG AS IT LIFTS ACROSS
FAR WRN LAKE SUPERIOR WED AFTN. 20-30KT WINDS ARE EXPECTED OVER MUCH
OF THE LAKE TUE NIGHT INTO WED. MAY SEE GALE FORCE GUSTS OVER FAR
WRN LAKE SUPERIOR IN THE NE WINDS AHEAD OF THE LOW TUE NIGHT AND
THEN IN THE WESTERLY WINDS ACROSS MAINLY CENTRAL LAKE SUPERIOR ON
THU AS THE LOW LIFTS N OF THE AREA. WINDS WILL DIMINISH TO UNDER
20KT FRI...AND THEN BEGIN TO INCREASE AGAIN ON SAT AHEAD OF THE NEXT
COLD FRONT MOVING OUT ACROSS THE PLAINS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KC
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...KC
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
258 PM CDT TUE AUG 18 2015
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 258 PM CDT TUE AUG 18 2015
VERY POWERFUL LOW PRESSURE MOVING FROM SOUTHWEST MN TO THE ARROWHEAD
REGION BY WEDNESDAY EVENING. IT IS VERY RARE TO SEE SUCH A STRONG
LOW PRESSURE SYSTEM IN THE SUMMER. IN FACT IT MAY WELL RIVAL THE LOW
PRESSURE RECORD FOR MSP. THE HRRR AND HOPWRF ARE IN GOOD AGREEMENT
AND HAVE DONE WELL THE LAST FEW HOURS. RADAR AND OBS SUPPORT THE
IDEA OF LESS PRECIPITATION IN TERMS OF AMOUNTS AND LESS CHANCES FOR
THUNDER AFTER 02Z THIS EVENING ACROSS THE AREA. DRY SLOT REALLY TOOK
OVER FOR THIS EVENT IN SRN MN. EXPECT THE COMMA HEAD WRAP-AROUND
PRECIPITATION TO AFFECT WESTERN MN LATE THIS AFTERNOON AND SLOWLY
LIFT EAST AND NORTH THROUGH THE EVENING AND OVERNIGHT HOURS. MAIN
PRECIPITATION WILL BE OVER WRN MN AND EXTENDING TO THE ARROWHEAD. WE
CAN EXPECT SCATTERED RAIN AND AN ISOLATED SHOWER OVER CENTRAL MN
INTO WRN WI THROUGH THE OVERNIGHT HOURS...MAYBE DRIZZLE. RAIN SHOULD
DIMINSH TOWARD MORNING AND THEN SEE AN INCREASE BY MID DAY. STRONG
WINDS WILL MOVE IN OVERNIGHT WITH GUSTS INTO THE MID 30 MPH RANGE
WEDNESDAY AFTERNOON WITH MOSTLY CLOUDY SKIES AND COOL TEMPERATURES.
VERY MUCH LIKE OCTOBER.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 258 PM CDT TUE AUG 18 2015
PICKING UP THE FORECAST WEDNESDAY NIGHT...THE FOCUS REMAINS GETTING
THIS INCREDIBLY STRONG MID AUGUST SYNOPTIC SCALE STORM SYSTEM OUT OF
HERE. BY THIS POINT...THE SURFACE LOW SHOULD BE POSITIONED OVER
WESTERN LAKE SUPERIOR AND SLIDING NORTHEAST. IT WILL BE ESSENTIALLY
VERTICALLY STACKED AND BEGIN WEAKENING OVERNIGHT. THE HIGHLY
AMPLIFIED 500MB TROUGH WILL INTRODUCE DRY NORTHWESTERLY FLOW INTO
WESTERN MN WHICH WILL EXPAND EASTWARD BY THURSDAY MORNING. DRY AIR
WILL ACCOMPANY THE NORTHWESTERLY FLOW...SO WE`LL SEE THE CLOUDS
BEGIN TO CLEAR FROM WEST TO EAST OVERNIGHT IN WESTERN MN...THROUGH
WESTERN WI BY MIDDAY THURSDAY. WITH CLEARING SKIES...AND THE LOW
MOVING OFF...WE`LL SEE TEMPERATURES REBOUND INTO THE MID 70S FOR
HIGHS. WESTERLY WINDS AT THE SURFACE OF 10-15 MPH ARE EXPECTED
THURSDAY...SO MUCH LESS WINDY THAN WEDNESDAY.
BY FRIDAY...A LOW PRESSURE SYSTEM WILL BE DEVELOPING NEAR
MONTANA...AND WE WILL BE ON THE BACK SIDE OF THE SURFACE RIDGE AXIS
ASSOCIATED WITH A SURFACE HIGH SLIDING EAST FROM THE CENTRAL PLAINS
TOWARD THE OHIO RIVER VALLEY....WHICH MEANS AN INCREASE IN SOUTHERLY
WINDS IS EXPECTED. WIND SPEEDS ARE FORECAST TO BE AROUND 15-20 MPH
WITH GUSTS OVER 20...AND TEMEPRATURES WILL WARM INTO THE LOW 80S
ONCE AGAIN. MAYBE MORE NOTICEABLY...WILL BE THE DEW POINTS RISING
INTO THE MID 60S BY FRIDAY AFTERNOON.
FOR THE WEEKEND...THE AFOREMENTIONED SYSTEM IN MONTANA WILL BE THE
FEATURE OF CONCERN. THE SURFACE LOW IS EXPECTED TO PROGRESS
EASTWARD ALONG THE INTERNATIONAL BORDER SATURDAY THROUGH
SUNDAY...BUT A NORTH-SOUTH ORIENTED COLD FRONT WILL BE THE FOCUS FOR
SHOWER AND THUNDERSTORM ACTIVITY TO DEVELOP IN OUR AREA...MOST
LIKELY SATURDAY AFTERNOON THROUGH THE OVERNIGHT HOURS. THIS SHOULD
BE A PROGRESSIVE LINE OF THUNDERSTORMS ALONG THE BOUNDARY...SO BY
SUNDAY MORNING WE SHOULD BE BACK IN DRIER NORTHWESTERLY FLOW AND
COOLER TEMEPRATURES. WILL HAVE TO SEE HOW THIS SYSTEM DEVELOPS IN
THE FUTURE MODEL GUIDANCE AS TIMING ISSUES ARE QUITE COMMON THIS FAR
OUT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1259 PM CDT TUE AUG 18 2015
A VERY MESSY TAF PERIOD AS DRY SLOT IS REALLY OVER TAKING AREA
AND LIMITING PRECIPITATION CHANCES FOR THE AFTERNOON AS WELL AS THE
POTENTIAL FOR ANY SEVERE WEATHER LATER. ON TOP OF THAT VERY STRONG
EASTERLY WINDS IN THE 40KT RANGE ACROSS SOUTH CENTRAL MN NOTED EARLY
THIS AFTERNOON AND ARE REFLECTED IN THE KRWF FOR A SHORT PERIOD.
WILL KEEP MENTION OF TSRA IN TAFS FOR THE EARLY AFTERNOON HOURS IN
THE EASTERN PART OF MN AND WESTERN WI BUT CONFIDENCE IS WANING. DO
EXPECT CEILINGS TO REMAIN LOW AND BE AROUND THE 007 TO 012 FOOT
LEVEL DEPENDING ON TIME OF NIGHT AND ANY SUBSEQUENT SHOWER
ACTIVITY. FOR SURE WE CAN EXPECT WEDNESDAY TO BE VERY BREEZY WITH
LOW CLOUDS AND ISOLATED SHOWERS...VERY UNLIKE MID AUGUST AND MORE
LIKE OCTOBER.
KMSP...THE LATEST MODEL TRENDS ARE DECREASING ANY TSRA POTENTIAL
FOR THE LATER AFTERNOON AND EARLY EVENING HOURS AND RADAR IS
SUPPORTING THAT AT THIS POINT IN TIME. WILL KEEP THUNDER IN THE
TEMPO GROUP FOR NOW BUT DO NOT HAVE VERY GOOD CONFIDENCE ON THAT
ACTUALLY HAPPENING. COULD EASILY SEE A TAF AMD. DO EXPECT CEILINGS
TO REMAIN LOW BUT IT MAY SCATTER OUT FROM TIME TO TIME. A WINDY
DAY ON TAP AT MSP TOMORROW WITH A FEW ISOLATED SHOWERS. WIND WILL
BE THE ISSUE WITH AIRFIELD OPS...NOT SHRA.
/OUTLOOK FOR KMSP/
THU...VFR. WINDS W 10-15 KTS.
FRI...VFR. WINDS S 10-15 KTS.
SAT...VFR WITH MVFR/TSRA POSSIBLE LATE. WIND S AT 15G20 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...DRL
LONG TERM...SPD
AVIATION...DRL
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
700 PM CDT WED AUG 19 2015
.SHORT TERM...(This Evening through Friday Night)
Issued at 400 PM CDT WED AUG 19 2015
Can`t beat this weather...October in mid August. Better enjoy it
while it lasts.
Deep upper trough extending from MN through eastern KS into OK will
continue tracking east tonight. Water vapor imagery shows a weak
vorticity max dropping down the back side of the trough across
western IA. Widely scattered instability showers have popped as a
result. HRRR trend supports low-end slight chance PoPs over northern
MO until about sunset. Most likely only sprinkles. Otherwise,
heating based stratocu cloud cover from NE into the CWA should
dissipate with loss of daytime heating and leave skies cloud free by
midnight. Could be flirting with record lows tomorrow morning. MCI
record min is 53 and STJ is 48.
Temperatures will rebound, but remain below average on Thursday,
before returning closer to seasonal on Friday. Warming will be the
result of the cooler/drier air being pulled away as the upper trough
moves east vs return flow from a retreating surface high. But even
the warm-up will be pleasant by summer standards as dewpoints will
remain in the 50s on Thursday and only increase into the lower 60s
on Saturday. Sure beats the upper 60s to lower 70s which occur so
often this time of year.
Will leave the forecast rain-free through Friday except for a token
slight chance PoP over far northwest MO late Thursday night.
Rain chances begin to ramp up late Friday night into Saturday
morning as stronger isentropic ascent tied to increasing low-level
moisture and development of the nocturnal low-level jet.
.LONG TERM...(Saturday through Wednesday)
Issued at 400 PM CDT WED AUG 19 2015
The GFS, European, and Canadian models are all in good agreement
that this weekend will see a pattern very similar to the pattern
that moved through the area the past couple days. The models depict
an upper level trough will develop and slide east over the northern
states through the weekend. An associated cold front will advance
across the Central Plains ahead of the trough. The models show the
best chance for storms will be Saturday night into Sunday as the
upper level trough moves over the Dakotas and the cold front moves
through the forecast area. Initially, convection will occur across
MN and IA earlier Saturday evening before spreading further south
into the forecast area as the cold front interacts with increasing
moisture ahead of and along the front. Severe potential would be
limited if showers or cloud cover linger throughout the day on
Saturday as these could restrict surface heating and convection
later in the evening. Just like today, showers could linger on
Sunday morning after the passage of the cold front. Also,
temperatures will be lower than normal for August on Sunday into
Monday, and dry conditions will prevail after the lingering showers
dissipate on Sunday. Temperatures gradually increase throughout the
early part of the work week as upper level high pressure slowly
builds over the Plains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 700 PM CDT WED AUG 19 2015
Clear skies and light winds are expected overnight and through the
daytime hours on Thursday. Fog is expected to develop at KSTJ by the
early morning hours, reducing visibilities to LIFR for a few hours
until winds increase and fog can mix out; otherwise, conditions will
be VFR through the TAF period.
&&
.CLIMATE...
Issued at 400 PM CDT WED AUG 19 2015
Record low temperature/date for August 19th...
Kansas City (MCI) 53/1950
St. Joseph (STJ) 48/1981
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...MJ
LONG TERM...HEC
AVIATION...Laflin
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
355 PM CDT TUE AUG 18 2015
.SHORT TERM: (THROUGH LATE TONIGHT)
ISSUED AT 355 PM CDT TUE AUG 18 2015
PREFRONTAL CONVECTION HAS BLOWN UP ABOUT AS EXPECTED THIS AFTERNOON.
SEVERE THUNDERSTORM WATCH IS IN EFFECT UNTIL 900 PM THIS EVENING AND
WE`VE HAD SOME SPORADIC REPORTS OF TREE LIMBS DOWN WITH THE
STRONGEST STORMS. SBCAPE IN EXCESS OF 3000 J/KG INDICATED ON SPC
MESOANALYSIS PAGE AHEAD OF THE CONVECTION WITH A VIGOROUS SHORTWAVE
MOVING INTO WESTERN MISSOURI AT THIS TIME. MASS FIELDS ON SHORT-
RANGE GUIDANCE CONTINUE TO STREAM INSTABILITY UP INTO THE REGION
THROUGH THE EVENING...AND THIS LOOKS REASONABLE GIVEN THE POSITION
OF THE SHORTWAVE AND SURFACE FRONT. HAVE TO SAY, THE HRRR DID A
PRETTY GOOD JOB WITH THE CONVECTION THIS AFTERNOON, SO THE SHORT
RANGE FORECAST FOR TONIGHT IS BIASED HEAVILY TOWARD THE HRRR.
EXPECT STORMS CURRENTLY OVER EASTERN KANSAS TO CONTINUE TO DEVELOP
AND MOVE EASTWARD TONIGHT AHEAD OF THE SHORTWAVE. THERE WILL LIKELY
BE A LUL IN THE THUNDERSTORM ACTIVITY OVER OUR CWFA AFTER 00-02Z,
BUT THE STORMS CURRENTLY IN KANSAS WILL EVENTUALLY MOVE IN AFTER 04-
05Z. ADDITIONAL DEVELOPMENT IS ALSO POSSIBLE AHEAD OF THE KANSAS
STORMS. THE COLD FRONT WILL SWEEP INTO MISSOURI OVERNIGHT AND SHOULD
BE THROUGH CENTRAL AND INTO EASTERN MISSOURI BY 12Z.
CARNEY
.LONG TERM: (WEDNESDAY THROUGH NEXT TUESDAY)
ISSUED AT 355 PM CDT TUE AUG 18 2015
MODELS CONTINUE TO SUPPORT A FAST SURFACE FRONTAL SOLUTION WHILE
MAINTAINING A SIMILAR TIMING WITH THE UPPER LEVEL PROFILE. WHILE
THERE SHOULD STILL BE A NICE SLUG OF WIDESPREAD LIFT BUILDING IN
FROM LATE WEDNESDAY MORNING THRU EARLY EVENING...THE COLUMN WILL
BE VERY LIMITED THERMODYNAMICALLY...MEANING LIKE MOSTLY SHOWERS WITH
DIMINISHING CHANCES FOR THUNDER AS THE DAY GOES ALONG. DECENT RAIN
CHANCES ARE NOW EXPECTED TO LINGER INTO EARLY EVENING BEFORE THEN
MAKING A RAPID EXIT FROM SOUTHWEST TO NORTHEAST FOLLOWED QUICKLY BY
CLEARING SKIES.
WHAT WILL REMAIN IN ITS WAKE WILL BE A RARE COOL AND DRY PERIOD
BEGINNING LATE WEDNESDAY NIGHT THRU FRIDAY AFTERNOON WITH MIN TEMPS
DIPPING INTO THE 50S AND MAX TEMPS ONLY REACHING TO AROUND 80
DEGREES.
THE FRONTAL COMPLEX THAT HAD PUSHED TO OUR SOUTH ON WEDNESDAY
WILL THEN MOVE BACK TO THE NORTH BY SATURDAY TO ALLOW CHANCES FOR
THUNDERSTORMS TO RETURN AND PERSIST THRU THE WEEKEND WITH
TEMPERATURES BACK TO SEASONABLE AVERAGES.
IN YET ANOTHER SIGN THAT AUTUMN IS NOT TOO FAR OFF ANYMORE...ANOTHER
DECENTLY STRONG COLD FRONT PUSHES THRU LATE SUNDAY AND IS
EXPECTED TO BRING AN ENCORE OF THE COOL AND DRY PERIOD FOR MONDAY
AND TUESDAY OF NEXT WEEK.
SOME MODEL DISCREPANCIES THEN EXIST HEADING DEEPER INTO NEXT WEEK
BUT THE GENERAL THEME IS SUMMER THEN REMINDING US THAT IT IS NOT YET
DONE...WITH AN UPPER LEVEL RIDGE ATTEMPTING TO BUILD IN TO POSSIBLY
DELIVER ONE FINAL ROUND OF DANGEROUS HEAT AND HUMIDITY TO CLOSE OUT
AUGUST.
TES
&&
.AVIATION: (FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 641 AM CDT TUE AUG 18 2015
RADIATIONAL FOG WILL REMAIN POSSIBLE AT KSUS AND KCPS THROUGH 14Z,
OTHERWISE VFR FLIGHT CONDITIONS ARE EXPECTED THROUGH MIDDAY.
SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS
AFTERNOON WITH GOOD POTENTIAL FOR IMPACTS AT ALL OF THE TERMINALS.
I HAVE CONSERVATIVELY INTRODUCED TEMPO GROUPS AT ALL OF THE TERMINALS
FOR MVFR FLIGHT CONDITIONS, HOWEVER THE CONDITIONS COULD CERTAINLY
DROP TO IFR WITH GUSTY WINDS. ANOTHER ROUND OF THUNDERSTORMS IS
EXPECTED TO IMPACT THE TERMINALS THIS EVENING AS A COLD FRONT
PUSHES INTO THE AREA.
SPECIFICS FOR KSTL:
VFR FLIGHT CONDITIONS ARE EXPECTED THROUGH MIDDAY. SCATTERED TO
NUMEROUS THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON
ACROSS EASTERN MO WITH GOOD POTENTIAL FOR IMPACTS AT KSTL. I HAVE
CONSERVATIVELY INTRODUCED A TEMPO GROUP FOR MVFR FLIGHT CONDITIONS,
HOWEVER THE CONDITIONS COULD CERTAINLY DROP TO IFR WITH GUSTY
WINDS. ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED TO IMPACT THE
TERMINAL THIS EVENING AS A COLD FRONT PUSHES INTO THE AREA.
GLASS
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS SPRINGFIELD MO
1246 PM CDT TUE AUG 18 2015
...Updated Aviation Section...
.UPDATE...
Issued at 1246 PM CDT TUE AUG 18 2015
First batch of rain with embedded thunder has made its way into
the western portions of the outlook area. Earlier scattered
activity firing east of Highway 65 has had difficulty sustaining
itself so far, counter to what the HRRR has suggested. Modest
instability ahead of the incoming batch of rain should be more
than enough to sustain the current activity, if not result in an
increase embedded thunderstorm activity. Stronger cells will flirt
with severe limits, with hail to the size of quarters and wind
gusts to 60mph possible. Behind this line of showers/storms, a
brief break in the action is possible late this afternoon into
early this evening, but this should be short lived.
Heading into this evening, the incoming cold front should begin to
light up across Kansas and this will likely pose our best shot at
organized storms given the increase in shear. Still some questions
as to the potential severity of storms given the first batch of
rain moving through could tamper with potential instability. That
said, modest recovery later this afternoon warrants a continued
mention of marginally severe hail/wind.
Cold front comes through tonight and tomorrow will feature a stiff
change in weather conditions. Cloudy, showery and temperatures in
the 60s. An early taste of autumn!
&&
.SHORT TERM...(Today and Tonight)
Issued at 0220 AM CDT TUE AUG 18 2015
More active weather pattern will unfold today into tonight as
upper patten undergoes amplification. A lead impulse will track
eastward from Kansas today as a seasonably deep upper trough digs
into the northern Plains. Expect convection coming out of Kansas
to be on diminishing trend as it spreads eastward into western
Missouri this morning. However expect an increase in coverage of
showers and thunderstorms this afternoon across the Missouri
Ozarks where the lower troposphere can destabilize ahead of the
advancing cloud shield. A few robust updrafts could develop but
the severe risk during the day will be limited due to relatively
weak deep layer shear.
Additional convection will ignite across Kansas into northern
Oklahoma later this afternoon in the wake of the lead impulse and
ahead of the cold front within region of substantial 500 MB height
falls. This activity will spread east southeast into the region
this evening into the overnight hours. This activity will present
at least a marginal risk for severe storms particularly from
southeastern Kansas into central Missouri where the airmass may
recover in the wake of earlier convection. In addition deep layer
shear will increase as the mid level flow increases in response to
the approaching upper level trough.
Overall confidence in this forecast is high.
.LONG TERM...(Wednesday through Monday)
Issued at 0220 AM CDT TUE AUG 18 2015
The cold front will push to the south of the area Wednesday
morning as the upper level trough continues to evolve. The trough
axis will remain to the west much of the day Wednesday with
another shortwave swinging around the base of the trough and into
the region later in the day. This resulting synoptic scale lift
will generate post frontal showers and thunderstorms through much
of the day Wednesday.
The clouds and precipitation along with cool air advection will
result in a much cooler day Wednesday with highs generally in the
60s to lower 70s.
Clearing will take place from west to east Wednesday night as the
upper trough axis swings to the east. A cooler and comfortable
airmass will settle into the area Thursday as surface pressure
builds into the Ozarks.
The upper pattern will become more zonal late week into the
weekend. The chance of convection could return as early as Friday
but more so Friday night and Saturday as a minor shortwave
traverses east across the region.
A northern stream shortwave will push across the northern tier of
the U.S. late in the weekend. This system will drag a cold front
across the region Sunday brining another chance of showers and
thunderstorms.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1246 PM CDT TUE AUG 18 2015
Challenging forecast over the next 24 hours as there will be
several opportunities for rain/thunder, a cold front passage and
increasing risk of MVFR to IFR ceilings. Line of showers and
embedded thunderstorms will move across the region this afternoon,
with somewhat of a break in the action from later this afternoon
into early this evening. A cold front will then begin to approach
from the northwest this evening, with showers/storms refiring on
this boundary as it moves into the region. Overall, ceilings
should behave with the afternoon/evening activity, with the
potential for MVFR visibility. Cold front passage will be
overnight tonight with rain and perhaps some embedded thunder
spreading into the region heading into Wednesday morning. There is
an increasing risk of IFR ceilings at all sites. MVFR visibility
is possible at SGF/BBG.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
UPDATE...gagan
SHORT TERM...Foster
LONG TERM...Foster
AVIATION...Gagan
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
1136 PM MDT MON AUG 17 2015
.AVIATION...
06Z TAF CYCLE
A DISTURBANCE ALOFT AND ASSOCIATED JET STREAK OF HIGHER WIND
SPEEDS ALOFT ARE PUSHING INTO COLORADO AND NORTHERN NEW MEXICO
LATE THIS EVENING. THIS WILL CONTINUE TO PRODUCE SOME ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS...MOSTLY ACROSS NORTH CENTRAL
TO EASTERN SECTIONS OF NEW MEXICO. THIS ACTIVITY WILL MOVE FAIRLY
QUICKLY AT 20 TO 30 KT WITH BRIEF DOWNPOURS AND SOME ERRATIC
GUSTY WINDS TO 35 KT POSSIBLE. MOST OF THE ACTIVITY SHOULD SUBSIDE
BEFORE 18/1200UTC. ANY STORM ACTIVITY DURING THE DAYTIME TUESDAY
WILL BE FROM A COLD FRONT ENTERING NORTHEASTERN NEW MEXICO. WINDS
WILL SHIFT AND BECOME GUSTY FROM THE NORTHEAST TO EAST BEHIND THIS
FRONT WHILE REMAINING AREAS GENERALLY OBSERVE GUSTY NORTHWEST
WINDS OF 15 TO 30KT.
52
&&
.PREV DISCUSSION...911 PM MDT MON AUG 17 2015...
.UPDATE...
STRONG TO SEVERE STORMS HAVE DIMINISHED OR MOVED OUT OF THE CWA.
CONSEQUENTLY REMOVED MENTION FROM WX GRID AND DECREASED POPS FOR
THE EVENING...SHORT TERM MODELS NOT AS BULLISH AS THEY WERE A FEW
HOURS AGO WITH HOLDING ONTO PRECIPITATION IN THE EAST AFTER
MIDNIGHT. UPDATED ZFP ALREADY TRANSMITTED.
&&
.PREV DISCUSSION...341 PM MDT MON AUG 17 2015...
.SYNOPSIS...
SEVERE THUNDERSTORMS WILL REMAIN POSSIBLE THROUGH THE EVENING
ACROSS MUCH OF NORTHEAST NEW MEXICO. LARGE HAIL AND DAMAGING WINDS
WILL BE THE MAIN THREATS. THEREAFTER...A DRYING TREND WILL
COMMENCE. MUCH FEWER STORMS ARE EXPECTED TUESDAY THROUGH THURSDAY.
A BACK DOOR FRONT ON TUESDAY NIGHT WILL RESULT IN FALL LIKE
TEMPERATURES ON WEDNESDAY ACROSS THE EASTERN PLAINS. LATER IN THE
WEEK...A SLOW INCREASE IN THUNDERSTORM ACTIVITY IS POSSIBLE.
&&
.DISCUSSION...
SEVERE WEATHER REMAINS POSSIBLE THROUGH THIS EVENING ACROSS THE
NORTHEAST QUADRANT OF NM. 35 TO 40KTS OF BULK SHEAR AND CAPE UP TO
2500 J/KG PER LAPS ANALYSIS WILL PROVIDE AN ENVIRONMENT VERY
SUITABLE FOR STORMS TO BECOME SEVERE AS THEY MOVE OFF THE HIGHER
TERRAIN INTO THE NE PLAINS. A JET MAX WILL ALSO AID IN TSTM
DEVELOPMENT AND FOCUS ACTIVITY ACROSS THE NE. LARGE HAIL AND
DAMAGING WIND GUSTS WILL BE THE MAIN THREAT WITH THIS ACTIVITY.
THE LATEST HRRR SHOWS MOST OF THIS INITIAL ROUND OF ACTIVITY
EXITING NM BY MID EVENING...BUT ANOTHER ROUND OF STORMS MAY
DEVELOP LATER THANKS TO OUTFLOW BOUNDARIES MOVING IN FROM SE CO.
THE UPPER LEVEL TROUGH WILL CROSS THE CENTRAL ROCKIES TONIGHT AND
THE ASSOCIATED PACIFIC FRONT WILL SLIDE THROUGH CENTRAL AND
WESTERN NM. MUCH DRIER AIR BEHIND THE TROUGH AND BREEZY WINDS WILL
MIX DOWN TO THE SURFACE...RESULTING IN SOME OF THE LOWEST
DEWPOINTS WE HAVE SEEN ACROSS THE NW SINCE THE SPRING.
MEANWHILE...THE BACK DOOR SEGMENT OF THE FRONT WILL SLIDE DOWN THE
PLAINS. A FEW STORMS MAY DEVELOP ALONG THE FRONT AND ALONG THE
EAST SLOPES OF THE SANGRES...BUT THE DEEP LAYER OF DRIER AIR ALOFT
WILL LIMIT COVERAGE SIGNIFICANTLY. THE FRONT SHOULD PUSH THRU THE
GAPS OF THE CENTRAL MTN CHAIN TUESDAY NIGHT...BUT THE MOISTURE IT
BRINGS WITH IT SHOULD QUICKLY MIX OUT ON WEDNESDAY WITHIN THE RGV.
ON WEDNESDAY...SOME OF THE MOISTURE ACROSS THE PLAINS WILL ALSO
MIX OUT. CONTINUE LOW LEVEL SOUTHEASTERLY FLOW...HOWEVER...MAY
YIELD A STRAY SHOWER OR TSTM ALONG THE CENTRAL MTN CHAIN...BUT
CONFIDENCE IS PRETTY LOW. THE BIGGER STORY WILL BE THE MUCH COOLER
TEMPS ACROSS THE EAST IN THE WAKE OF THE BACK DOOR FRONT. MOST
AREAS WILL STRUGGLE TO REACH 80.
ANOTHER WEAK WAVE LOOKS TO CROSS NM ON THURSDAY...BUT CONTINUED
DRY AIR OVER THE STATE WILL CONTINUE TO LIMIT TSTM ACTIVITY. SE
PORTIONS OF THE CWA MAY BE FAVORED FOR AN ISOLATED STORM WHERE
BETTER LOW LEVEL MOISTURE EXISTS.
CONFIDENCE REMAINS LOW IN THE FORECAST FRIDAY AND BEYOND. MODELS
CONTINUE TO SUGGEST SOME MOISTURE WILL SEEP UP INTO NM AND WE WILL
SEE A GRADUAL INCREASE IN TSTM ACTIVITY. OF MORE CERTAINTY LOOKS
TO BE ANOTHER BACK DOOR COLD FRONT SLIDING DOWN THE PLAINS OVER
THE WEEKEND WHICH WILL HELP TO MOISTEN UP LOW LEVELS...BUT THE
PARENT TROUGH MAY BRING DRIER AIR OVER NORTHERN NM ONCE AGAIN.
STAY TUNED.
34
&&
.FIRE WEATHER...
FAIRLY ACTIVE AND VIGOROUS BATCH OF SHOWERS AND STORMS AS OF MID
AFTN STRETCHING FROM THE SANGRE DE CRISTOS AND NE HIGHLANDS AND
PLAINS SOUTH AND SOUTHWESTWARD TO THE CENTRAL HIGHLANDS AND MID TO
LOWER RIO GRANDE VALLEY. A FEW HAVE ALREADY BECOME SEVERE ACROSS
THE NORTHERN PORTION OF THIS AREA. THIS ACTIVITY WILL EXPAND SOME
ACROSS THE EASTERN PLAINS THROUGH THE EVE. MOST OF THE NW THIRD OF
THE STATE WILL BE DRY THROUGH THE EVENING AND THIS DRYING TREND
WILL EXPAND SOUTH AND EAST OVER THE NEXT 24 TO 48 HOURS IN THE
WAKE OF A SIGNIFICANT AND EARLIER THAN USUAL MID TO UPPER LOW
PRESSURE TROUGH. ACCOMPANYING AND IN THE WAKE OF THE TROUGH WILL
BE A STRENGTHENING NORTHWEST FLOW ALOFT OVER CENTRAL AND NORTHERN
NEW MEXICO THAT WILL USHER THE MUCH DRIER AIR MASS FROM NW TO SE.
WEST AND NW NEAR SFC WINDS WILL BE PERKING UP SIGNIFICANTLY ACROSS
MUCH OF NORTHERN NM TUE IN RESPONSE TO THE INCREASED NW FLOW ALOFT.
SOME SPOTTY AND LOCALIZED CRITICAL FIRE WEATHER CONDITIONS WILL BE
POSSIBLE OVER AREAS MAINLY BETWEEN THE NW PLATEAU AND THE HIGH
TERRAIN OF RIO ARRIBA AND LOS ALAMOS COUNTIES. THESE CONDITIONS ARE
NOT EXPECTED TO BE WIDESPREAD AND GIVEN CURRENT FUEL STATUS AND
LOW/MODERATE FIRE DANGER...FIRE WEATHER HIGHLIGHTS WILL NOT BE
ISSUED. STILL MIN RH WILL REALLY CRATER OCCUR ON TUE. SURFACE DEW
POINTS WILL DROP INTO THE 20S AND 30S ACROSS THE NW THIRD TO
NEARLY HALF OF FCST AREA TUE AFTN.
DAYTIME TEMPS WILL LOWER BY 5 TO 15 DEGREES...THE MOST EAST...WED IN
WAKE OF AN ASSOCIATED PACIFIC FRONT AS WELL AS A BACKDOOR SEGMENT OF
THE FRONTAL SYSTEM. THE LATTER WILL REACH NE AREAS ON TUESDAY...WITH
THE MAIN SOUTHWARD SURGE TUE NIGHT INTO WED. THIS SHOULD BRING AT
LEAST A MODERATE EAST GAP WIND INTO PORTIONS OF THE RIO GRANDE
VALLEY AND THUS DEW POINTS WILL RECOVER EAST OF THE CENTRAL
MOUNTAIN CHAIN AND TO A LESSER DEGREE INTO THE RIO GRANDE VALLEY FOR
WED.
THE WED TO THU PERIOD SHOULD FEATURE LITTLE OR NO THUNDER IN THE
FCST AREA. EXPECT WARMING TEMPERATURES AND SLIGHT MOISTURE INCREASE
FOR LATE WEEK AS HIGH PRESSURE BUILDS AND THE AIR MASS GRADUALLY
RECOVERS. EXCELLENT VENTILATION THE NEXT 3 TO 5 DAYS...EXCEPT THE
EAST HALF ON WED MAY ONLY REACH FAIR TO GOOD LVLS.
43
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1035 PM EDT WED AUG 19 2015
.SYNOPSIS...
UNSETTLED WEATHER WILL CONTINUE THROUGH THURSDAY. A WEAK COLD
FRONT WILL MOVE ACROSS THE AREA FRIDAY. LESS COVERAGE OF SHOWERS
AND THUNDERSTORMS CAN BE EXPECTED FRIDAY THROUGH EARLY NEXT WEEK
WITH TYPICAL LATE SUMMERTIME TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
AS OF 1000 PM WEDNESDAY...THE BRUNT OF A LARGE CONVECTIVE COMPLEX
WAS PASSING BY TO OUR N WITH THE SOUTHERN PORTION OF THIS AREA OF
THUNDERSTORMS MOVING ACROSS A PORTION OF THE FORECAST AREA...
BASICALLY N OF A FLO TO CPC TO BURGAW LINE. THE OVERALL INTENSITY
OF RAINFALL CONTINUES TO DIMINISH AND ALTHOUGH A BRIEF HEAVY
DOWNPOUR IS POSSIBLE...OVERALL RAINFALL RATES GOING FORWARD WILL
NOT BE SIGNIFICANT HERE FOR THE REMAINDER OF THE NIGHT.
ANOTHER MUCH SMALLER BATCH OF THUNDERSTORMS WAS ONGOING TO OUR SW
ACROSS SOUTHERN SOUTH CAROLINA. THE NORTHERN PERIPHERY OF THIS
AREA OF STORMS MAY SKIRT PORTIONS OF WILLIAMSBURG AND GEORGETOWN
COUNTIES...12-2 AM. A HEAVY DOWNPOUR IS POSSIBLE...BUT SEVERE
WEATHER IS NOT EXPECTED.
I AM INCLINED TO THINK THAT WE WILL GET SOME REDEVELOPMENT OF
CONVECTION OVER THE WARM OCEAN WATERS LATE TONIGHT AND EARLY THU
MORNING AS HAS BEEN THE CASE FOR THE LAST FEW NIGHTS. THE HIGH
RESOLUTION HRRR MODEL IS FINALLY BEGINNING TO SETTLE ON SUCH A
SOLUTION. IF THIS CONVECTION DOES INDEED MATERIALIZE...IT MAY
SKIRT PORTIONS OF THE COAST...MAINLY FROM THE GRAND STRAND THROUGH
CAPE FEAR EARLY IN THE MORNING.
GIVEN THE EXTENT AND MAGNITUDE OF THE RAINFALL TODAY AND TONIGHT...
WILL CONTINUE TO INCLUDE PATCHY LATE NIGHT FOG ACROSS PORTIONS OF
THE AREA.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...A MID LEVEL CYCLONE WILL MOVE ACROSS THE
GREAT LAKES WITH A BROAD ZONAL FLOW PUSHING A COLD FRONT ACROSS
THE AREA EARLY FRIDAY. BY THE END OF THE PERIOD MID LEVEL HIGH
PRESSURE BUILDS BACK IN FROM THE SOUTH WITH ANY APPRECIABLE
AFFECTS FROM THE FRONT BASICALLY GONE. FOR THURSDAY...WEAK SURFACE
TROUGHING WILL STILL RESIDE ACROSS THE AREA AND GOOD CHANCE POPS
REMAIN IN THE FORECAST. POPS DECREASE SOMEWHAT FOR FRIDAY AS THE
WEAK FRONT HAS A SIGNIFICANT SUBSIDENCE INVERSION IN THE 700-850MB
LAYER WHICH WILL MAKE CONVECTIVE DEVELOPMENT MORE CHALLENGING THAN
PREVIOUS DAYS. THERE REMAINS A VERY MOIST PROFILE HOWEVER AND
LOWER CHANCE POPS SHOULD BE A GOOD COMPROMISE. TEMPERATURES CHANGE
LITTLE THROUGH THE PERIOD WITH HIGHS IN THE 90S AND LOWS IN THE
70S.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 300 PM WEDNESDAY...COLD FRONT AND ITS ASSOCIATED MOISTURE
BOTH MOVING OFF THE COAST EARLY SATURDAY FOR A RAIN FREE WEEKEND
DESPITE SOME LAGGING UPPER LEVEL ENERGY PASSING THROUGH SUNDAY AND
SUNDAY NIGHT. MOISTURE RETURN WILL BEGIN GRADUALLY ON MONDAY AS A
PIEDMONT TROUGH DEVELOPS AND A MID LEVEL SHEAR LINE REMAINS ABOVE
THE AREA. COLD FRONT AND HEALTHY UPPER TROUGH DROP INTO THE AREA
TUESDAY AND WEDNESDAY AND LIKELY BRINGING SOME PRETTY UNSETTLED
WEATHER. OUR BEACHES MAY EVEN BEGIN SEEING SOME DANNY SWELLS EARLY
NEXT WEEK.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AS OF 00Z...SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE EARLY
THIS EVENING WITH THE BEST CHANCE OF VCTS AT KFLO/KLBT. THE BEST
CONFIDENCE OF SHOWERS WILL BE KCRE/KMYR AND KLBT. HI RESOLUTION
MODELS SUGGEST CONVECTION DYING OFF AND ENDING 4-5Z. TERMINALS
SHOULD REMAIN LARGELY VFR THIS EVENING. WIND DIRECTIONS ARE HIGHLY
VARIABLE DUE TO CONVECTIVE ACTIVITY...BUT SHOULD BECOME LIGHT SW
OR LIGHT AND VARIABLE AS THE EVENING PROGRESSES.
OVERNIGHT EXPECT BROKEN CLOUD COVER AT KFLO/KLBT TO TEMPER ANY
POTENTIAL FOG...ALTHOUGH CANT TOTALLY RULE OUT BRIEF MVFR VSBYS.
BEST POTENTIAL WOULD BE AT KLBT. SOME MID LEVEL LIFT SUGGEST
POTENTIAL ISOLATED SHOWERS AT KFLO/KLBT OVERNIGHT BUT MODELS PLAY
IT DOWN. AT THE COASTAL TERMINALS DO NOT EXPECT ANY FOG ISSUES
OVERNIGHT. SOME LIFT IN THE PRE-DAWN HOURS SUGGEST AN EARLY START
TO SHOWER ACTIVITY ESPECIALLY AT KILM...BECOMING MORE WIDESPREAD
BY THE MID MORNING HOURS AT ALL COASTAL TERMINALS. TSRA LIKELY
COASTAL TERMINALS IN THE MORNING. CONVECTION WORKS INLAND OF THE
COASTAL TERMINALS BY EARLY AFTERNOON. WINDS WILL BE SW-W EARLY
BECOMING SW BY MID-LATE MORNING.
EXTENDED OUTLOOK...VFR...WITH SCATTERED SHOWERS AND THUNDERSTORMS
THROUGH FRIDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 PM WEDNESDAY...SOUTHWEST WINDS WILL REMAIN ACROSS THE
WATERS THROUGH THE NIGHT. WIND SPEEDS WILL BE UP TO 15 KT. SEAS 2
TO 3 FT. A 8 TO 9 SECOND ESE SWELL WILL REMAIN AND IN THE COMING
DAYS THIS SWELL WILL ONLY INCREASE IN STRENGTH. WE SHOULD AGAIN
SEE CONVECTION DEVELOPING ACROSS THE WATERS WITH THE APPROACH OF
DAYBREAK THU.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...THE PIEDMONT TROUGH WILL BECOME MORE A
LITTLE BETTER DEFINED THURSDAY AND WIND FIELDS WILL SHOULD RESPOND
WITH A SOUTHWEST FLOW OF 10-15 KNOTS...MOSTLY IN THE LOWER END OF
THE RANGE. A WEAK FRONT WILL PUSH ACROSS THE WATERS EARLY FRIDAY
WITH THE FRONT AND THE LAND BREEZE PROVIDING A BRIEF OFFSHORE
FLOW. BY LATER IN THE DAY LIGHT AND VARIABLE WINDS DEVELOP UNDER A
WEAK PRESSURE PATTERN. AS FOR SEAS...GENERALLY 2-3 FEET THROUGH
THE PERIOD.
LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 PM WEDNESDAY...NORTHEAST WINDS ON SATURDAY AS COLD FRONT
SLOWLY MOVES OFF TO OUR SOUTH. WITH NO BIG PUSH OF HIGH PRESSURE
BEHIND THIS BOUNDARY WIND SPEEDS WILL REMAIN VERY LIGHT. NORTHEAST
OR EAST WINDS ON SUNDAY AS THE BOUNDARY DISSIPATES SOUTH OF THE
AREA. A MORE TYPICAL SOUTHWESTERLY WIND SHOULD RETURN ON MONDAY AS A
PIEDMONT TROUGH BEGINS TO DEVELOP.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...RJD
SHORT TERM...SHK
LONG TERM...MBB
AVIATION...MRR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
700 AM EDT TUE AUG 18 2015
.SYNOPSIS...SOUTHWEST FLOW WILL TRANSPORT MOISTURE-RICH AIR INTO
CENTRAL NORTH CAROLINA. MEANWHILE A SERIES OF UPPER LEVEL
DISTURBANCES EMBEDDED IN THIS FLOW WILL MOVE ACROSS THE AREA. THE
COMBINATION OF THESE FEATURES WILL RESULT IN ENHANCED RAIN CHANCES
THROUGH MUCH OF THE WEEK.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 700 AM TUESDAY...
CURRENT FORECAST ON TRACK WITH RADAR SHOWING A SHIELD OF LIGHT RAIN
MOVING W TO E ACROSS NORTH-CENTRAL NC ATTM...ALONG AND AHEAD OF AN
MID/UPPER VORT MOVING ACROSS THE NC FOOTHILLS ATTM. MADE SOME TWEAKS
TO THE GRIDS FOR THE NEXT FEW HOURS TO SHOW CATEGORICAL POPS ACROSS
OUR NORTHERN ZONES...AND CHANCE POPS SOUTH. AS THIS FEATURE MOVES
NE LATER THIS MORNING...WE`RE STILL LOOKING FOR THE PRECIP TO
TRANSITION TO MORE SCATTERED/SHOWER IN NATURE...WITH SHOWERS AND
PERHAPS A FEW ISOLD TSTMS DEVELOPING/EXPANDING IN COVERAGE FROM W TO
E ACROSS THE REST OF CENTRAL NC DURING THE LATE MORNING AND
AFTERNOON HOURS.
PREV NEAR TERM DISC AS OF 235 AM TUESDAY...
LATEST MESOANALYSIS SHOWS THAT MOISTURE IS INCREASING FROM THE SOUTH
AS EXPECTED...AS THE PATTERN CONTINUES TO EVOLVE AND FLOW BECOMES
MORE UNIFORM FROM THE SOUTH AND SOUTHWEST. LATEST WATER VAPOR SHOWS
THE OLD CLOSED LOW OVER THE LOWER OH VALLEY HAS OPENED UP AND LIFTED
NORTH UP OVER INDIANA...AND HAS BECOME EMBEDDED WITHIN THE LONGWAVE
TROUGH DEEPENING OVER THE MIDDLE OF THE COUNTRY. EXTENDING SOUTH
FROM THIS WAVE IS A SHEAR AXIS THAT EXTENDS ACROSS THE APPALACHIANS
AND INTO UPSTATE SC. THIS FEATURE...COUPLED WITH THE NORTHWARD SURGE
OF MOISTURE...HAS PROVIDED THE MECHANISM AND FORCING FOR THE CURRENT
AREA OF LIGHT RAIN NOW MOVING ACROSS THE TRIAD REGION SOUTH TO THE
CHARLOTTE AREA. THE AREA OF RAIN ACROSS UPSTATE SC IS ALONG AND
AHEAD OF THE SHORTWAVE AT THE TAIL END OF THE AFOREMENTIONED SHEAR
AXIS. THESE FEATURES ARE PROGGED TO LIFT TO THE ENE TODAY...AND
LATEST CAMS INCLUDING THE HRRR WELL-DEPICT THESE FEATURES AND
SUGGESTS THAT THE TWO AREAS OF LIGHT RAIN WILL SPREAD EAST ACROSS
CENTRAL NC THIS MORNING INTO THE EARLY AFTERNOON. GIVEN THE
EXTENSIVE CLOUD COVER AND LIMITED INSTABILITY...WE EXPECT THE PRECIP
TO REMAIN STRATIFORM AND MAINLY LIGHT THROUGH THE MORNING HOURS.
THEN AS THE SHEAR AXIS BEGINS TO LIFT TO OUR NORTH...WE MAY BEGIN TO
SEE BREAKS IN THE CLOUDS AND SOME SUNSHINE LATE THIS MORNING AND
DURING THE AFTERNOON...WHICH WILL ALLOW FOR THE REMAINING PRECIP TO
TRANSITION TO MORE CONVECTIVE AND SCATTERED IN NATURE...WITH PERHAPS
SOME THUNDER AND LOCALIZED HEAVY DOWNPOURS. GIVEN THE HIGH PWAT
ENVIRONMENT AND SLOW MOVEMENT...LOCALIZED POOR DRAINAGE FLOODING
WILL BE THE PRIMARY IMPACT CONCERN WITH THE HEAVIER CELLS THIS
AFTERNOON. AS FOR TEMPS...MAV AND MET CONTINUE TO EXHIBIT A WIDE
SPREAD IN FORECAST VALUES FOR TODAY...WITH THE COOLER MAV SUGGESTING
READINGS RANGING FROM THE UPPER 70S NW TO MID 80S S/SE...WHILE THE
NAM IS SEVERAL DEGREES WARMER ACROSS THE TRIAD AND TRIANGLE REGIONS.
WITH THE CLOUD AND PRECIP COVERAGE THE PRIMARY FACTORS...WE FEEL
THAT A BLEND OF THE TWO IS WARRANTED BECAUSE SOME SUNSHINE IS
EXPECTED THIS AFTERNOON...ESP SOUTH OF HWY 64. THUS...HIGHS AROUND
80 ACROSS THE TRIAD...LOW-MID 80S TRIANGLE...MID 80S S OF HWY 64.
THE CHANCE FOR SCATTERED SHOWERS AND ISOLD TSTMS WILL CONTINUE
TONIGHT AS SEVERAL WEAK DISTURBANCES EMBEDDED IN THE SW FLOW
TRAVERSE THE AREA. LOWS WITHIN A COUPLE DEGREES OF 70.
&&
.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 235 AM TUESDAY...
LITTLE CHANGE IN THE PATTERN...WHICH WILL FEATURE A LONGWAVE TROUGH
OVER THE MIDDLE OF THE COUNTRY AND A RIDGE EXTENDING ACROSS FL INTO
THE GOMEX. SW FLOW BETWEEN THESE FEATURES ACROSS THE SOUTHEAST
STATES WILL KEEP THE FLOW OF MOISTURE-RICH AIR INTO OUR AREA GOING.
THAT COUPLED WITH A SERIES OF DISTURBANCES EMBEDDED WITHIN THE SW
FLOW WILL MEAN THE RISK FOR SCATTERED SHOWERS AND TSTMS WILL
CONTINUE ACROSS OUR AREA THROUGH THE PERIOD. THE SCATTERED NATURE OF
THE SHOWERS AND TSTMS MEANS IT WON`T BE RAINING DURING THE ENTIRE
TIME...BUT IT WORTH POINTING OUT THAT ANY OF THE HEAVIER CELLS WILL
BE CAPABLE OF PRODUCING HEAVY DOWNPOURS AND LOCALIZED POOR DRAINING
FLOODING. WITH ENHANCED CLOUDINESS AND RAIN CHANCES...TEMPS SHOULD
REMAIN A DEGREE OR TWO BELOW NORMAL. HIGHS FROM THE MID 80S NORTH
TO UPPER 80S SOUTH. LOWS WEDNESDAY NIGHT 70-73.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 235 AM TUESDAY...
FOR THE PERIOD THURSDAY AND THURSDAY NIGHT...500MB HEIGHTS ARE
FORECAST BY BOTH THE NAM AND THE GFS TO RISE THURSDAY INTO THURSDAY
NIGHT. THIS SHOULD SERVE TO BOTH SLOW AND WEAKEN THE SURFACE FRONT
MOVING INTO CENTRAL NORTH CAROLINA. WIND SPEEDS GENERALLY LIGHTEN
THROUGH THE COLUMN WHICH SHOULD LIMIT LOW-LEVEL CONVERGENCE AS WELL
AS ANY DIFFLUENCE ALOFT. 850MB LIFT IS WEAK...BEST THURSDAY NIGHT
COMPARED TO DURING THE DAY THURSDAY...WHEN THE GFS IS ACTUALLY DRY
OVER MUCH OF CENTRAL NORTH CAROLINA. PRECIPITABLE WATER VALUES...
THOUGH...ARE STILL FORECAST IN VICINITY OF TWO INCHES WITH HIGH K
INDICES AND DECENT 850MB THETA-E VALUES. THE GFS ALSO FORECASTS A
MODEST 700MB SHORTWAVE MOVING THROUGH CENTRAL NORTH CAROLINA DURING
THE DAY AND EVENING...WITH PRONOUNCED 700MB NVA LATE THURSDAY NIGHT.
CONSIDERING THE AVAILABLE MOISTURE...MODEST INSTABILITY EVEN ON THE
GFS WITH MUCAPE OF 500-1000J/KG...AND THE NAM FORECAST OF GREATER
LOW-LEVEL CONVERGENCE WITH MORE OF A SOUTHERLY SURFACE WIND AS
OPPOSED TO THE MORE WESTERLY GFS FORECAST...PRUDENT TO CONTINUE AT
LEAST A CHANCE OF SHOWERS AND A THUNDERSTORM OR TWO FOR THIS PART OF
THE FORECAST. THIS DESPITE THE SINGLE-DIGIT MAV MOS POPS AT KRDU AND
KFAY FOR THE DAY THURSDAY. HIGHS FOR THURSDAY ARE A LITTLE TOUGH TO
GAUGE ANTICIPATING CONSIDERABLE CLOUD COVER THAT COULD BE OFFSET BY
EVEN SLIGHT PERIODS OF SUN GIVEN THE HIGH 1000-850MB THICKNESSES.
GUIDANCE HIGHS ARE 90 TO 95 AND WILL PLAN TO GO BELOW THOSE ROUGHLY
A COUPLE OF DEGREES. OVERNIGHT LOWS THURSDAY NIGHT WITHIN A DEGREE
OR THREE OF 70.
FRIDAY THROUGH MONDAY...THE SLOW-MOVING SURFACE FRONT SHOULD BE
LOCATED OVER THE EASTERN CAROLINAS...GRADUALLY MOVING SOUTH WHILE
LIKELY WASHING OUT INTO THE EARLY PART OF THE WEEKEND. AS SURFACE
HIGH PRESSURE IS FORECAST TO NUDGE SOUTH BEHIND THE FRONT...COARSE
MODEL SOUNDINGS FROM BOTH THE GFS AND THE ECMWF SUGGEST
PRECIPITATION CHANCES MAY BE MORE LIMITED FRIDAY...RELATIVELY HIGHER
TOWARD INTERSTATE 95 CLOSER TO THE FRONT. CONTINUED WITH A SLIGHT
CHANCE FOR SHOWERS FRIDAY OVER THE WESTERN PIEDMONT WITH CHANCES
MAINLY ALONG AND EAST OF U.S. 1...ALTHOUGH IF THE MODEL SOUNDINGS
VERIFY THESE CHANCES MAY END UP BEING TOO HIGH. EVEN IF SHOWER
CHANCES ARE LESS BOTH THE GFS AND ECMWF PROVIDE FOR DECENT MEAN
MOISTURE AND PARTICULARLY UPPER-LEVEL MOISTURE LINGERING WHICH WOULD
MAKE THE DAY PARTLY SUNNY AT BEST.
OVER THE WEEKEND...THE SURFACE FRONT SHOULD DIMINISH JUST SOUTH OF
CENTRAL NORTH CAROLINA SATURDAY AS WEAK HIGH PRESSURE BUILDS IN.
UNDER RIDGING ALOFT SATURDAY...ANY SHOWERS SHOULD BE DIFFICULT TO
COME BY. WILL RETAIN A SLIGHT CHANCE OF A SHOWER TOWARD INTERSTATE
95 WHERE MOISTURE OVERALL SHOULD BE A LITTLE HIGHER AND SURFACE
PRESSURES A LITTLE LOWER...WITH LIFT POSSIBLY AIDED BY A SEA BREEZE.
HEIGHTS ALOFT START TO FALL SUNDAY INTO MONDAY AHEAD OF ANOTHER
SURFACE FRONT THAT SHOULD BE MOVING TOWARD CENTRAL NORTH CAROLINA
FROM THE NORTHWEST. COARSE ECMWF MODEL SOUNDINGS ARE FAIRLY CAPPED
SUNDAY WHILE GFS COARSE MODEL SOUNDINGS SHOW COOLER TEMPERATURES
ALOFT AND GREATER INSTABILITY...ENOUGH FOR AT LEAST ISOLATED/SLIGHT
CHANCES FOR SHOWERS SUNDAY WITH THE RELATIVELY HIGHER CHANCES THAT
DAY OVER THE WESTERN PIEDMONT WHERE ANY INSTABILITY SHOULD BE
GREATER.
BY MONDAY...TIMING DIFFERENCES WITH THE APPROACH OF THE SURFACE
FRONT ENSURE CONTINUATION OF CHANCES FOR SHOWERS AND STORMS THEN...
HIGHEST EARLIER MONDAY OVER THE WESTERN PIEDMONT THEN CHANCES
THROUGHOUT CENTRAL NORTH CAROLINA BY MONDAY AFTERNOON THROUGH MONDAY
NIGHT. BOTH THE ECMWF AND GFS COARSE MODEL SOUNDINGS SHOW SUFFICIENT
INSTABILITY AND LAYER LAPSE RATES FOR AT LEAST SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS THE AREA BY MONDAY AFTERNOON. FOR HIGH
TEMPERATURES...LEANED TOWARD THE MEE MOS GUIDANCE WHICH SEEMED TO BE
A GOOD BLEND BETWEEN THE COOLER MEX MOS AND WARM 1000-850MB
THICKNESSES. HIGHS 85 TO 90 FRIDAY AND 87 TO 92 BY MONDAY. OVERNIGHT
LOWS MOSTLY 65 TO 70... ABOUT A CATEGORY COOLER SATURDAY NIGHT WHEN
IT WOULD SEEM THERE WOULD BE THE GREATER CHANCE OF A COMBINATION OF
SOMEWHAT DRIER LOW-LEVEL AIR AND AREAS OF CLEARING.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 700 AM TUESDAY......
THROUGH 12Z WED: RADAR CONTINUES TO SHOW A SHIELD OF LIGHT RAIN
MOVING W TO E ACROSS NORTH CENTRAL NC. FLT CONDITIONS UNDER THIS
RAIN ARE MOSTLY LOW-VFR OR MVFR...WITH LOCAL IFR BEING REPORTED
INVOF OF THE STRONGER RAIN ECHOES. AS THE MORNING PROGRESSES...WE
EXPECT THE RAIN TO TRANSITION TO MORE SHOWER (CONVECTIVE) IN
NATURE...WITH ADDITIONAL SCATTERED SHOWERS DEVELOP ACROSS THE
REMAINDER OF CENTRAL NC. WHILE IT WON`T BE RAINING EVERYWHERE AND
ALL DAY...WHERE IT IS RAINING EXPECT MVFR OR UPPER-IFR CONDITIONS.
ISOLD TSTMS ARE ALSO POSSIBLE THIS AFTERNOON...WHICH WILL RESULT IN
LOCAL DOWNPOURS AND IFR CONDITIONS...AND VARIABLE WINDS BRIEFLY
GUSTING UP TO 30KT. AFT 19/01Z...EXPECT LOW-VFR CONDITIONS WITH CIGS
AROUND 5K FT. PATCHY FOG IS POSSIBLE LATE OVERNIGHT...PARTICULARLY
INVOF SITES THAT RECEIVED HEAVIER RAIN DURING THE DAY.
AFTER 12Z WED: WITH LITTLE CHANGE IN THE PATTERN THROUGH THE REST OF
THE WEEK...LOOK FOR SCATTERED SHOWERS AND TSTMS WHICH WILL RESULT IN
LOCALIZED MVFR OR IFR CONDITIONS. VFR CONDITIONS OUTSIDE OF SHOWER
AND TSTM ACTIVITY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...RAH
NEAR TERM...RAH
SHORT TERM...RAH
LONG TERM...DJF
AVIATION...RAH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
235 AM EDT TUE AUG 18 2015
.SYNOPSIS...SOUTHWEST FLOW WILL TRANSPORT MOISTURE-RICH AIR INTO
CENTRAL NORTH CAROLINA. MEANWHILE A SERIES OF UPPER LEVEL
DISTURBANCES EMBEDDED IN THIS FLOW WILL MOVE ACROSS THE AREA. THE
COMBINATION OF THESE FEATURES WILL RESULT IN ENHANCED RAIN CHANCES
THROUGH MUCH OF THE WEEK.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 235 AM TUESDAY...
LATEST MESOANALYSIS SHOWS THAT MOISTURE IS INCREASING FROM THE SOUTH
AS EXPECTED...AS THE PATTERN CONTINUES TO EVOLVE AND FLOW BECOMES
MORE UNIFORM FROM THE SOUTH AND SOUTHWEST. LATEST WATER VAPOR SHOWS
THE OLD CLOSED LOW OVER THE LOWER OH VALLEY HAS OPENED UP AND LIFTED
NORTH UP OVER INDIANA...AND HAS BECOME EMBEDDED WITHIN THE LONGWAVE
TROUGH DEEPENING OVER THE MIDDLE OF THE COUNTRY. EXTENDING SOUTH
FROM THIS WAVE IS A SHEAR AXIS THAT EXTENDS ACROSS THE APPALACHIANS
AND INTO UPSTATE SC. THIS FEATURE...COUPLED WITH THE NORTHWARD SURGE
OF MOISTURE...HAS PROVIDED THE MECHANISM AND FORCING FOR THE CURRENT
AREA OF LIGHT RAIN NOW MOVING ACROSS THE TRIAD REGION SOUTH TO THE
CHARLOTTE AREA. THE AREA OF RAIN ACROSS UPSTATE SC IS ALONG AND
AHEAD OF THE SHORTWAVE AT THE TAIL END OF THE AFOREMENTIONED SHEAR
AXIS. THESE FEATURES ARE PROGGED TO LIFT TO THE ENE TODAY...AND
LATEST CAMS INCLUDING THE HRRR WELL-DEPICT THESE FEATURES AND
SUGGESTS THAT THE TWO AREAS OF LIGHT RAIN WILL SPREAD EAST ACROSS
CENTRAL NC THIS MORNING INTO THE EARLY AFTERNOON. GIVEN THE
EXTENSIVE CLOUD COVER AND LIMITED INSTABILITY...WE EXPECT THE PRECIP
TO REMAIN STRATIFORM AND MAINLY LIGHT THROUGH THE MORNING HOURS.
THEN AS THE SHEAR AXIS BEGINS TO LIFT TO OUR NORTH...WE MAY BEGIN TO
SEE BREAKS IN THE CLOUDS AND SOME SUNSHINE LATE THIS MORNING AND
DURING THE AFTERNOON...WHICH WILL ALLOW FOR THE REMAINING PRECIP TO
TRANSITION TO MORE CONVECTIVE AND SCATTERED IN NATURE...WITH PERHAPS
SOME THUNDER AND LOCALIZED HEAVY DOWNPOURS. GIVEN THE HIGH PWAT
ENVIRONMENT AND SLOW MOVEMENT...LOCALIZED POOR DRAINAGE FLOODING
WILL BE THE PRIMARY IMPACT CONCERN WITH THE HEAVIER CELLS THIS
AFTERNOON. AS FOR TEMPS...MAV AND MET CONTINUE TO EXHIBIT A WIDE
SPREAD IN FORECAST VALUES FOR TODAY...WITH THE COOLER MAV SUGGESTING
READINGS RANGING FROM THE UPPER 70S NW TO MID 80S S/SE...WHILE THE
NAM IS SEVERAL DEGREES WARMER ACROSS THE TRIAD AND TRIANGLE REGIONS.
WITH THE CLOUD AND PRECIP COVERAGE THE PRIMARY FACTORS...WE FEEL
THAT A BLEND OF THE TWO IS WARRANTED BECAUSE SOME SUNSHINE IS
EXPECTED THIS AFTERNOON...ESP SOUTH OF HWY 64. THUS...HIGHS AROUND
80 ACROSS THE TRIAD...LOW-MID 80S TRIANGLE...MID 80S S OF HWY 64.
THE CHANCE FOR SCATTERED SHOWERS AND ISOLD TSTMS WILL CONTINUE
TONIGHT AS SEVERAL WEAK DISTURBANCES EMBEDDED IN THE SW FLOW
TRAVERSE THE AREA. LOWS WITHIN A COUPLE DEGREES OF 70.
&&
.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 235 AM TUESDAY...
LITTLE CHANGE IN THE PATTERN...WHICH WILL FEATURE A LONGWAVE TROUGH
OVER THE MIDDLE OF THE COUNTRY AND A RIDGE EXTENDING ACROSS FL INTO
THE GOMEX. SW FLOW BETWEEN THESE FEATURES ACROSS THE SOUTHEAST
STATES WILL KEEP THE FLOW OF MOISTURE-RICH AIR INTO OUR AREA GOING.
THAT COUPLED WITH A SERIES OF DISTURBANCES EMBEDDED WITHIN THE SW
FLOW WILL MEAN THE RISK FOR SCATTERED SHOWERS AND TSTMS WILL
CONTINUE ACROSS OUR AREA THROUGH THE PERIOD. THE SCATTERED NATURE OF
THE SHOWERS AND TSTMS MEANS IT WON`T BE RAINING DURING THE ENTIRE
TIME...BUT IT WORTH POINTING OUT THAT ANY OF THE HEAVIER CELLS WILL
BE CAPABLE OF PRODUCING HEAVY DOWNPOURS AND LOCALIZED POOR DRAINING
FLOODING. WITH ENHANCED CLOUDINESS AND RAIN CHANCES...TEMPS SHOULD
REMAIN A DEGREE OR TWO BELOW NORMAL. HIGHS FROM THE MID 80S NORTH
TO UPPER 80S SOUTH. LOWS WEDNESDAY NIGHT 70-73.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 235 AM TUESDAY...
FOR THE PERIOD THURSDAY AND THURSDAY NIGHT...500MB HEIGHTS ARE
FORECAST BY BOTH THE NAM AND THE GFS TO RISE THURSDAY INTO THURSDAY
NIGHT. THIS SHOULD SERVE TO BOTH SLOW AND WEAKEN THE SURFACE FRONT
MOVING INTO CENTRAL NORTH CAROLINA. WIND SPEEDS GENERALLY LIGHTEN
THROUGH THE COLUMN WHICH SHOULD LIMIT LOW-LEVEL CONVERGENCE AS WELL
AS ANY DIFFLUENCE ALOFT. 850MB LIFT IS WEAK...BEST THURSDAY NIGHT
COMPARED TO DURING THE DAY THURSDAY...WHEN THE GFS IS ACTUALLY DRY
OVER MUCH OF CENTRAL NORTH CAROLINA. PRECIPITABLE WATER VALUES...
THOUGH...ARE STILL FORECAST IN VICINITY OF TWO INCHES WITH HIGH K
INDICES AND DECENT 850MB THETA-E VALUES. THE GFS ALSO FORECASTS A
MODEST 700MB SHORTWAVE MOVING THROUGH CENTRAL NORTH CAROLINA DURING
THE DAY AND EVENING...WITH PRONOUNCED 700MB NVA LATE THURSDAY NIGHT.
CONSIDERING THE AVAILABLE MOISTURE...MODEST INSTABILITY EVEN ON THE
GFS WITH MUCAPE OF 500-1000J/KG...AND THE NAM FORECAST OF GREATER
LOW-LEVEL CONVERGENCE WITH MORE OF A SOUTHERLY SURFACE WIND AS
OPPOSED TO THE MORE WESTERLY GFS FORECAST...PRUDENT TO CONTINUE AT
LEAST A CHANCE OF SHOWERS AND A THUNDERSTORM OR TWO FOR THIS PART OF
THE FORECAST. THIS DESPITE THE SINGLE-DIGIT MAV MOS POPS AT KRDU AND
KFAY FOR THE DAY THURSDAY. HIGHS FOR THURSDAY ARE A LITTLE TOUGH TO
GAUGE ANTICIPATING CONSIDERABLE CLOUD COVER THAT COULD BE OFFSET BY
EVEN SLIGHT PERIODS OF SUN GIVEN THE HIGH 1000-850MB THICKNESSES.
GUIDANCE HIGHS ARE 90 TO 95 AND WILL PLAN TO GO BELOW THOSE ROUGHLY
A COUPLE OF DEGREES. OVERNIGHT LOWS THURSDAY NIGHT WITHIN A DEGREE
OR THREE OF 70.
FRIDAY THROUGH MONDAY...THE SLOW-MOVING SURFACE FRONT SHOULD BE
LOCATED OVER THE EASTERN CAROLINAS...GRADUALLY MOVING SOUTH WHILE
LIKELY WASHING OUT INTO THE EARLY PART OF THE WEEKEND. AS SURFACE
HIGH PRESSURE IS FORECAST TO NUDGE SOUTH BEHIND THE FRONT...COARSE
MODEL SOUNDINGS FROM BOTH THE GFS AND THE ECMWF SUGGEST
PRECIPITATION CHANCES MAY BE MORE LIMITED FRIDAY...RELATIVELY HIGHER
TOWARD INTERSTATE 95 CLOSER TO THE FRONT. CONTINUED WITH A SLIGHT
CHANCE FOR SHOWERS FRIDAY OVER THE WESTERN PIEDMONT WITH CHANCES
MAINLY ALONG AND EAST OF U.S. 1...ALTHOUGH IF THE MODEL SOUNDINGS
VERIFY THESE CHANCES MAY END UP BEING TOO HIGH. EVEN IF SHOWER
CHANCES ARE LESS BOTH THE GFS AND ECMWF PROVIDE FOR DECENT MEAN
MOISTURE AND PARTICULARLY UPPER-LEVEL MOISTURE LINGERING WHICH WOULD
MAKE THE DAY PARTLY SUNNY AT BEST.
OVER THE WEEKEND...THE SURFACE FRONT SHOULD DIMINISH JUST SOUTH OF
CENTRAL NORTH CAROLINA SATURDAY AS WEAK HIGH PRESSURE BUILDS IN.
UNDER RIDGING ALOFT SATURDAY...ANY SHOWERS SHOULD BE DIFFICULT TO
COME BY. WILL RETAIN A SLIGHT CHANCE OF A SHOWER TOWARD INTERSTATE
95 WHERE MOISTURE OVERALL SHOULD BE A LITTLE HIGHER AND SURFACE
PRESSURES A LITTLE LOWER...WITH LIFT POSSIBLY AIDED BY A SEA BREEZE.
HEIGHTS ALOFT START TO FALL SUNDAY INTO MONDAY AHEAD OF ANOTHER
SURFACE FRONT THAT SHOULD BE MOVING TOWARD CENTRAL NORTH CAROLINA
FROM THE NORTHWEST. COARSE ECMWF MODEL SOUNDINGS ARE FAIRLY CAPPED
SUNDAY WHILE GFS COARSE MODEL SOUNDINGS SHOW COOLER TEMPERATURES
ALOFT AND GREATER INSTABILITY...ENOUGH FOR AT LEAST ISOLATED/SLIGHT
CHANCES FOR SHOWERS SUNDAY WITH THE RELATIVELY HIGHER CHANCES THAT
DAY OVER THE WESTERN PIEDMONT WHERE ANY INSTABILITY SHOULD BE
GREATER.
BY MONDAY...TIMING DIFFERENCES WITH THE APPROACH OF THE SURFACE
FRONT ENSURE CONTINUATION OF CHANCES FOR SHOWERS AND STORMS THEN...
HIGHEST EARLIER MONDAY OVER THE WESTERN PIEDMONT THEN CHANCES
THROUGHOUT CENTRAL NORTH CAROLINA BY MONDAY AFTERNOON THROUGH MONDAY
NIGHT. BOTH THE ECMWF AND GFS COARSE MODEL SOUNDINGS SHOW SUFFICIENT
INSTABILITY AND LAYER LAPSE RATES FOR AT LEAST SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS THE AREA BY MONDAY AFTERNOON. FOR HIGH
TEMPERATURES...LEANED TOWARD THE MEE MOS GUIDANCE WHICH SEEMED TO BE
A GOOD BLEND BETWEEN THE COOLER MEX MOS AND WARM 1000-850MB
THICKNESSES. HIGHS 85 TO 90 FRIDAY AND 87 TO 92 BY MONDAY. OVERNIGHT
LOWS MOSTLY 65 TO 70... ABOUT A CATEGORY COOLER SATURDAY NIGHT WHEN
IT WOULD SEEM THERE WOULD BE THE GREATER CHANCE OF A COMBINATION OF
SOMEWHAT DRIER LOW-LEVEL AIR AND AREAS OF CLEARING.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 235 AM TUESDAY......
THROUGH 06Z WED: RADAR SHOWS A SHIELD OF LIGHT RAIN BEGINNING TO
OVERSPREAD CENTRAL NC FROM W TO E...WITH CIGS AND VSBY LOWERING TO
MVFR CRITERIA ACROSS THE WESTERN PIEDMONT AND TRIAD REGIONS. SITES
FARTHER EAST WILL ALSO SEE FLT CONDITIONS GRADUALLY WORSEN BETWEEN
09Z-14Z. LOOK FOR MVFR FLT CONDITIONS TO PERSIST THROUGH 16-
18Z...THEN PRECIP IS EXPECTED TO COME MORE SCATTERED AND CONVECTIVE
IN NATURE THIS AFTERNOON AS BREAKS IN THE CLOUDS ALLOWS FOR SOME
SUNSHINE. SCATTERED SHOWERS/TSTMS THIS AFTERNOON AND EVENING WILL BE
CAPABLE OF BRIEFLY LOWERING FLT CONDITIONS TO IFR...ALONG WITH
LOCALIZED WIND GUSTS OF 20-30KTS.
AFTER 06Z WED: WITH LITTLE CHANGE IN THE PATTERN THROUGH THE REST OF
THE WEEK...LOOK FOR SCATTERED SHOWERS AND TSTMS WHICH WILL RESULT IN
LOCALIZED MVFR OR IFR CONDITIONS. VFR CONDITIONS OUTSIDE OF SHOWER
AND TSTM ACTIVITY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...RAH
NEAR TERM...RAH
SHORT TERM...RAH
LONG TERM...DJF
AVIATION...RAH
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
240 PM CDT TUE AUG 18 2015
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 242 PM CDT TUE AUG 18 2015
FORECAST CHALLENGE FOR TONIGHT IS WHICH HI RES MODEL TO FOLLOW FOR
EVOLUTION OF LOW PRESSURE SYSTEM OVER FAR SERN SD AS IT MOVES
EAST AND THEN NORTH...CLIPPING SOUTHERN AND EASTERN PORTIONS OF
THE CWA. HRRR HAS CONSISTENTLY VERIFIED WITH PLACEMENT OF PRECIP
BEST EACH HOUR...ALTHOUGH EARLIER RUNS THAT SPREAD RAIN AS FAR
NORTH AS FARGO WERE THOUGHT TO BE OVERLY BULLISH AND I HAD FAVORED
THE NMM/ARW...WHICH KEPT PRECIP FURTHER SOUTH WITH THE NE FLOW IN
SFC-H850 LAYER. HOWEVER...15Z HRRR RUN DID A VERY GOOD JOB WITH
PLACEMENT OF PRECIP VERIFIED BY 19Z RADAR IMAGERY. THEREFORE WILL
CONTINUE HRRR TRENDS THROUGH THE EVENING THROUGH 06Z...THEN A FCST
BLEND THROUGH END OF EVENT FOR OUR CWA.
TONIGHT AND TOMORROW...PRECIP OVER SOUTHWEST MN WILL CONTINUE TO
LIFT FROM SW MN INTO W CNTRL MN...HOWEVER WITH SFC LOW MOVING
NE...DO NOT EXPECT RAIN TO LIFT MUCH FURTHER NORTH THAN HILLSBORO
WITHIN THE RRV. LOW BEGINS TO LIFT MORE NORTHWARD AFTER
MIDNIGHT...EVENTUALLY MOVING OVER LAKE SUPERIOR WED AFTN. QUESTION
IS HOW MUCH PRECIP WILL BACK INTO NW MN...AND CURRENT TRENDS ARE
KEEPING MOST OF THE NORTHERN VALLEY AND KITTSON/MARSHALL/NW POLK
COUNTIES DRY. 00Z ECMWF WAS THE FURTHEST WEST AND HAVE DISCOUNTED
IT...PREFERRING A GFS/GEM/NAM BLEND FOR WEDNESDAY POPS. HIGHEST
RAINFALL RATES WITHIN DEFORMATION ZONE SHOULD BE OVER CNTRL
MN...WHERE HPC QPF IS SHOWING UP TO TWO AND A QUARTER INCHES OF
PRECIP WITH A SHARP...DECLINING GRADIENT WESTWARD INTO THE
SOUTHERN VALLEY. CURRENT PRECIP TOTAL THOUGHTS ARE AROUND HALF AN
INCH IN FARGO...LITTLE IF ANY IN GRAND FORKS...RISING TO AROUND 2
INCHES AS FAR EAST AS PARK RAPIDS.
WED NIGHT...SYSTEM PULLS OUT OF LAKE SUPERIOR REGION INTO CNTRL
ONTARIO...SLOWLY PULLING PRECIP OUR OF FAR EAST AND NORTHEASTERN
ZONES BY 12Z THU. CLEARING IN THE WEST...IN ADDITION TO RELAXING
PRESSURE GRADIENT WINDS...WILL ALLOW OVERNIGHT LOWS TO FALL INTO
THE UPPER TO MID 40S ACROSS MOST OF THE REGION...WARMEST IN THE
FAR EAST WHERE CLOUD COVER WILL LINGER OVERNIGHT.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 242 PM CDT TUE AUG 18 2015
THURSDAY AND FRIDAY...HIGH PRESSURE MOVES INTO REGION BRINGING
INCREASED SOLAR AND REBOUNDING TEMPERATURES TO NEAR SEASONAL NORMS
ON THURSDAY. RETURN FLOW SETS UP THU NIGHT INTO FRIDAY AND WEAK
SOUTHERLY FLOW THROUGH THE DAY FRIDAY WILL RESULT IN TEMPS
CLIMBING BACK INTO THE MID 80S.
THU NIGHT INTO FRIDAY...PASSING MID LEVEL TROUGH SATURDAY WILL DRAG
ANOTHER COLD FRONT ACROSS THE REGION. TIMING OF FRONT WOULD BRING
BEST T CHANCES ACROSS EASTERN HALF OF THE FA. SUNDAY WILL BE
COOLER FOLLOWED BY MODERATING TEMPERATURES INTO EARLY NEXT WEEK
WITH DRY CONDITIONS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 154 PM CDT TUE AUG 18 2015
MAIN CHALLENGE WILL BE TIMING OF PCPN INTO FAR AND BJI. FAR COULD
SEE SOME SHRA MOVING IN LATE THIS AFTERNOON WITH BEST CHANCES AFT
00Z. OVERALL CIGS HERE SHOULD REMAIN VFR. BJI IN SAME BOAT WITH
HIGHER CONFIDENCE IN STEADIER RAIN AND LOWER CIGS AFT 00Z AND
CONTINUING THROUGH MOST OF THE PERIOD. REMAINDER OF TAF SITES LIKELY
TO MISS OUT ON RAIN WITH VFR MID/UPPER LEVEL CIGS.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
SHORT TERM...SPEICHER
LONG TERM...SPEICHER/VOELKER
AVIATION...VOELKER
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
155 PM CDT TUE AUG 18 2015
.UPDATE...
ISSUED AT 154 PM| CDT TUE AUG 18 2015
MORNING UPDATE FOCUS ON POPS FOR THIS AFTERNOON AND TONIGHT AS
LOW PRESSURE SYSTEM EVOLVES IN SD. OVERALL...12Z HRRR VERIFIED
BEST WITH PLACEMENT OF CURRENT PRECIP AND A FINGER OF PRECIP
EXTENDING FROM S CNTRL ND INTO THE JAMESTOWN AREA. HRRR DOES
SPREAD THIS PRECIP NORTH AND EAST...TAKING PRECIP FURTHER NORTH
THAN INHERITED GRIDS. WITH THE NE FLOW I AM AGAINST THIS THINKING
AND WILL MAKE ADJUSTMENTS TO CAPTURE THE PRECIP EXTENDING INTO
THE SW...BUT KEEP LIKELIES SOUTH OF FARGO AND BEMIDJI UNTIL MORE
12Z MODEL DATA HAS CAME IN. FOR AFTN HOURS...PREFER NMM AND ARW
WHICH KEEP PRECIP FURTHER SOUTH (AGAINST BORDERS WITH NEIGHBORING
OFFICES TO THE SOUTH)...BUT WILL SEE HOW 12Z GFS AND CANADIAN
INITIALIZE BEFORE MAKING TOO MANY CHANGES.
UPDATE ISSUED AT 651 AM CDT TUE AUG 18 2015
KJMS NOW REPORTING A SPRINKLE FROM A MID LEVEL CEILING. REGIONAL
RADARS SHOW A THIN BAND OF ECHOES FROM KJMS BACK INTO NORTH
CENTRAL SD. OTHER ECHOES MOVING INTO NORTHEAST SD WHICH MAY TAKE A
WHILE LONGER TO MOVE UP INTO THE SOUTHERN FA. BASICALLY THE
FORECAST REMAINS ON TRACK.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 327 AM CDT TUE AUG 18 2015
MAIN FORECAST CHALLENGE WILL BE THE INTENSE LOW PRESSURE SYSTEM
THAT WILL AFFECT THE AREA TODAY THRU WED/WED NIGHT. AS FOR RIGHT
NOW...SEEING MID AND HIGH LEVEL CLOUDS CONTINUING TO STREAM INTO
THE FA. WINDS STILL ON THE LIGHTER SIDE BUT THEY ARE TRYING TO
TURN MORE NORTHEAST AS THE SFC LOW TAKES SHAPE OVER THE CENTRAL
PLAINS. REGIONAL RADARS SHOW MAIN SWATH OF RAIN MOVING INTO THE
MISSOURI VALLEY OF WEST CENTRAL SD WITH WEAKER ECHOES FINGERING
NORTH INTO SOUTHERN ND. KBIS DID PICK UP A FEW SPRINKLES AND THIS
SAME BAND IS TRYING TO POKE UP TOWARD KJMS. SOME OF THIS MAY
EXTEND INTO THE FAR SW FA BY MORNING BUT IT WOULD ONLY BE VERY
LIGHT. THE SYSTEM SHOULD GET GOING DURING THE DAY TODAY AND
CONTINUE INTO WED/WED NIGHT.
THIS IS AN INTERESTING SYSTEM NO DOUBT BRINGING A WIDER SWATH OF
RAIN TO THE SOUTH AND EAST...GUSTIER WINDS AND COOL TEMPS. WPC
TRACKS THE LOW FROM SOUTH CENTRAL NEBRASKA AT 12Z TUE TO NEAR KMSP
BY 00Z WED...THEN TO NEAR LAKE SUPERIOR BY 12Z WED. THIS MIMICS
THE TRACK OF THE 00Z GFS BEST. HOWEVER OTHER MODELS ARE NOT IN
GOOD AGREEMENT WITH THIS TRACK AND NOT SHOWING THE CONSISTENCY
HOPED FOR AS THE EVENT IS GETTING CLOSER. GLAD THIS IS NOT A
WINTER STORM SYSTEM...AS NAILING DOWN SNOWFALL AMOUNTS WITH SUCH
WIDE MODEL VARIATIONS WOULD BE TOUGH. SINCE THIS WILL BE RAIN THE
MAIN THING IS WHERE THE HEAVIER AMOUNTS FALL. FOR THIS FA...WILL
BE ON THE COOL/NW SIDE OF THE LOW TRACK SO NOT EXPECTING ANY
CONVECTIVE/HEAVIER RAIN AMOUNTS. MOST MODELS GIVING A LONG
DURATION STEADY RAIN IN THE 1 TO 2 INCH RANGE...AND THIS WOULD
MAINLY BE ACROSS THE FAR SOUTHERN RED RIVER VALLEY INTO PORTIONS
OF WEST CENTRAL MN.
00Z ECMWF CAME IN WITH A FURTHER WEST SFC LOW TRACK...FROM SOUTH
CENTRAL NE AT 12Z TUE TO NW IA BY 00Z WED...NEAR KMSP BY 12Z WED
AND THEN UP TO KDLH BY 00Z THU. THIS IS A SLOWER EVOLUTION TOO
WHICH WOULD KEEP THE RAIN/WIND IN LONGER THAN THE WPC SOLUTION.
WILL HAVE TO SEE IF FUTURE RUNS COME INTO BETTER AGREEMENT. EITHER
WAY SINCE IT HAS BEEN DRY HAVE NO HEAVY RAINFALL TYPE HEADLINES.
WINDS WILL BE GUSTY TONIGHT INTO WED ESPECIALLY ACROSS THE MN FA
BUT COULD EXTEND BACK INTO THE RED RIVER VALLEY.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 327 AM CDT TUE AUG 18 2015
WRAPAROUND PCPN SHOULD TAPER OFF ACROSS THE EASTERN FA ON WED
NIGHT...ALTHOUGH 00Z ECMWF WOULD HOLD IT THROUGH THU MORNING. THU
HIGHS SHOULD FINALLY REBOUND A LITTLE CLOSER TO MID AUG NORMALS.
FRIDAY TO MONDAY...MODELS IN FAIR AGREEMENT WITH THE BASIC IDEA OF A
WARM START TO THE WEEKEND WITH A SHORT WAVE AND FROPA BRINGING
THUNDER ACTIVITY TO THE ENTIRE CWFA THEN COOLING TEMPS DOWN IN ITS
WAKE. TIMING UNCERTAINTY REMAINS...CURRENT THINKING IS THAT SATURDAY
DAYTIME FROPA IS EXPECTED...WITH THE GFS A BIT FASTER IN THE SYSTEMS
PROGRESSION THAN THE ECMWF. SUNDAY MAY SEE AM SHOWERS IF THE SYSTEM
IS AS SLOW AS THE EC THEN DRY ON MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 154 PM CDT TUE AUG 18 2015
MAIN CHALLENGE WILL BE TIMING OF PCPN INTO FAR AND BJI. FAR COULD
SEE SOME SHRA MOVING IN LATE THIS AFTERNOON WITH BEST CHANCES AFT
00Z. OVERALL CIGS HERE SHOULD REMAIN VFR. BJI IN SAME BOAT WITH
HIGHER CONFIDENCE IN STEADIER RAIN AND LOWER CIGS AFT 00Z AND
CONTINUING THROUGH MOST OF THE PERIOD. REMAINDER OF TAF SITES LIKELY
TO MISS OUT ON RAIN WITH VFR MID/UPPER LEVEL CIGS.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...SPEICHER
SHORT TERM...GODON
LONG TERM...GODON/JK
AVIATION...SPEICHER
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1224 AM CDT TUE AUG 18 2015
.UPDATE...
ISSUED AT 1216 AM CDT TUE AUG 18 2015
QUICK UPDATE TO PRECIPITATION CHANCES AND TEMPERATURES. LATEST
MODEL GUIDANCE AND RADAR TRENDS INDICATE A SLOWER AND FURTHER
SOUTH PROGRESSION OF SHOWERS TONIGHT. TRIMMED POPS SOUTH AND
DELAYED THE EXPANSION EASTWARD BY A FEW HOURS. ALSO REMOVED THE
MENTION OF THUNDER NORTHER OF I-94. INSTABILITY IS NEARLY
NON-EXISTENT AND ONLY HEAVIER CONVECTIVE SHOWERS ALONG THE ND/SD
BORDER HAVE CONTAINED ANY LIGHTNING. SKIES WERE MOSTLY CLEAR NORTH
AND THIS WAS ALLOWING TEMPERATURES TO COOL FASTER THAN FORECAST.
THEREFORE...LOWERED TEMPERATURES A FEW DEGREES.
UPDATE ISSUED AT 947 PM CDT MON AUG 17 2015
SHOWERS WITH ISOLATED THUNDERSTORMS CONTINUE TO MOVE SLOWLY EAST
FROM THE SOUTHWEST PART OF THE STATE. THE MAIN QUESTION TONIGHT IS
HOW FAR NORTH TO GO WITH THE HIGHER POPS. THE LATEST 00Z NAM
SUGGESTS MOST OF THE RAIN WILL BE CONFINED TO THE ND / SD
BORDER...WHILE THE RAP AND HRRR STILL BRING IT NORTH OF I94. HAVE
INCREASED POPS IN THE SOUTH AND WEST TO CATEGORICAL...BUT TAPER
THEM RELATIVELY QUICKLY FARTHER NORTH.
UPDATE ISSUED AT 655 PM CDT MON AUG 17 2015
REGIONAL RADAR MOSAIC SHOWS SHOWERS AND ISOLATED THUNDERSTORMS
MOVING ACROSS SOUTHEAST MONTANA TOWARDS SOUTHWEST NORTH DAKOTA
AND NORTHWEST SOUTH DAKOTA. INSTABILITY ACROSS NORTH DAKOTA
REMAINS LIMITED...SO KEEPING THE MENTION OF THUNDERSTORMS AS
ISOLATED LOOKS REASONABLE. THE LATEST SHORT TERM MODELS STILL
FOCUS THE BEST RAIN CHANCES IN THE SOUTHWEST PART OF THE STATE
THIS EVENING...AND THE CURRENT FORECAST HAS THAT SCENARIO WELL
COVERED.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 342 PM CDT MON AUG 17 2015
CURRENT SURFACE ANALYSIS PLACES COOL HIGH PRESSURE OVER THE
NORTHERN PLAINS. UPPER LEVEL ANALYSIS PLACES BROAD TROUGH OVER THE
NORTH-CENTRAL CONUS WITH POTENT SHORT WAVE DIGGING OVER THE
NORTHERN ROCKIES INTO THE PLAINS. OVER OUR AREA...A FEW SHOWERS
CONTINUE OVER NORTH CENTRAL NORTH DAKOTA WITH A LITTLE JET STREAK
PASSING OVER...WHILE SHOWERS START TO WORK INTO THE WEST WITH THE
AFOREMENTIONED DIGGING SHORT WAVE.
FOR THE REMAINDER OF THIS AFTERNOON INTO TONIGHT...SHORT WAVE WILL
CONTINUE TO DIG TO THE SOUTHEAST WITH A BROAD AREA OF
PRECIPITATION DEVELOPING...PARTICULARLY OVER SOUTHEAST
MONTANA/EASTERN WYOMING INTO SOUTH DAKOTA. OUR AREA WILL BE ON THE
NORTHERN FRINGES WITH THE GREATEST PRECIPITATION CHANCES REMAINING
ALONG THE FAR SOUTHERN TIER OF THE STATE...DECREASING CHANCES
TOWARDS THE NORTH. INSTABILITY REMAINS LOW...THOUGH ENOUGH EXITS
FOR A FEW WEAKER THUNDERSTORMS TO DEVELOP.
ON TUESDAY...SYSTEM WILL CONTINUE ITS EASTERLY TRACK...CLOSING OFF
OVER EASTERN SOUTH DAKOTA. THIS WILL CONTINUE TO KEEP THE HIGHEST
CHANCES ALONG THE SOUTHERN TIER OF THE STATE. TEMPERATURES WILL BE
QUITE COOL FOR THIS TIME OF YEAR...WITH HIGHS SOUTH OF I-94
REMAINING IN THE 60S...WHILE AREAS TO THE NORTH MAY PUSH INTO THE
LOWER 70S.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 342 PM CDT MON AUG 17 2015
CHANCES FOR SHOWERS AND THUNDERSTORMS WILL LINGER INTO TUESDAY
NIGHT...AS A BROAD UPPER LEVEL TROUGH CONTINUES DIGGING EASTWARD
ACROSS THE NORTHERN PLAINS.
A SLOW WARMING TREND AND DRY WEATHER ARE EXPECTED WEDNESDAY INTO
EARLY FRIDAY...AS AN UPPER LEVEL SHORTWAVE RIDGE IS PROJECTED
EAST ACROSS THE AREA.
THE NEXT UPPER LEVEL TROUGH IS EXPECTED TO MOVE INTO THE NORTH
PLAINS BY LATE FRIDAY...BRINGING ANOTHER ROUND OF THUNDERSTORMS TO
THE STATE BY LATE FRIDAY INTO EARLY SUNDAY MORNING...HIGHLIGHTED
WELL WITHIN THE LONG RANGE MODELS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1216 AM CDT TUE AUG 18 2015
VFR CONDITIONS ARE EXPECTED AT ALL TAF SITES THROUGH THE TAF
PERIOD. RAIN IS LIKELY AT KDIK/KBIS THIS MORNING AND POSSIBLE AT
KJMS/KISN LATER IN THE DAY. BRIEF REDUCTIONS OF VIS AND CIGS ARE
POSSIBLE IN ANY HEAVIER SHOWERS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AJ
SHORT TERM...JJS
LONG TERM...AC
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1155 PM EDT WED AUG 19 2015
.SYNOPSIS...
A COLD FRONT WILL MOVE SLOWLY THROUGH THE REGION THURSDAY INTO
THURSDAY NIGHT. LOWER HUMIDITY AND MAINLY DRY WEATHER WILL RETURN
TO MOST OF CENTRAL PA FRIDAY THROUGH THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
SHOWER ACTIVITY IS FADING WITH THE LOSS OF HEATING AND INCREASED
STABILITY. THE HRRR CONTINUES WITH THE IDEA OF SCATTERED
ACTIVITY MEANDERING ABOUT FOR THE OVERNIGHT SO WHILE I LOWERED
POPS...I DID NOT ELIMINATE THE MENTION OF RAIN ALTOGETHER. IT DOES
LOOK LIKE MOST AREAS WILL REMAIN RAIN FREE FOR THE REST OF THE
NIGHT HOWEVER.
THE OVERNIGHT PERIOD WILL REMAIN WARM AND MUGGY WITH LOWS IN THE
UPPER 60S TO LOW 70S.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
AN INCREASE IN CYCLONIC FLOW ALOFT AHEAD OF IMPRESSIVE MID LEVEL
CYCLONE FOR THIS TIME OF YEAR OVER THE UPPER GREAT LAKES REGION...
AND STRENGTHENING OF THE S-SE LLJ SHOULD RESULT IN AN INCREASE IN
SHOWER ACTIVITY ONCE AGAIN AFTER 12Z. A BLEND OF NEAR AND SHORT
TERM MODEL QPF TARGETS AN AXIS OF PCPN FROM THE SRN DELMARVA INTO
ERN PA WHICH MAY BE ENHANCED BY SSERLY FEED OF ATLANTIC
MOISTURE.
THE SFC COLD FRONT IS FORECASTED TO MOVE THROUGH THE CENTRAL
MOUNTAINS BY LATE AFTERNOON AND THE SUSQUEHANNA VALLEY THURSDAY
EVENING.
THE BEST SHEAR VALUES LOOK TO BE NORTH AND WEST OF THE SPINE OF
THE APPALACHIANS WITH THE SREF INDICATING A 70% PROBABILITY OF
SHEAR GREATER THAN 30 KTS IN THE NORTHWEST MOUNTAINS AND WESTERN
LAURELS LATE TOMORROW AFTERNOON. SURFACE CAPE VALUES WILL RANGE
FROM 1000 TO 2000 J/KG IN THE AFTERNOON.
THE BIGGEST CONCERN FOR THURSDAY IS THE THREAT FOR FLASH FLOODING
AS WE HAVE ANOMALOUSLY HIGH PWATS BETWEEN TWO AND THREE STANDARD
DEVIATIONS ABOVE NORMAL. RFC FFG MOSAIC INDICATES THAT AMTS ARE
HIGHEST /2 TO 4 INCHES OVER A 6-HOUR PERIOD/ WHERE WE EXPECT THE
HEAVIEST RAIN TO FALL - ACROSS THE ERN HALF OF THE CWA THURSDAY
AFTERNOON AND NIGHT.
MODEL/ENSEMBLE CONSENSUS QPF STILL POINTS TWD JUST UNDER ONE INCH
ACROSS THE WESTERN PART OF THE CWA...AND 1-1.5 INCHES ACROSS THE
EAST...WITH OBVIOUSLY SOME HIGHER NARROW-BANDED 2+ INCH TOTALS.
HIGH TEMPERATURES ON THURSDAY WILL REMAIN MILD RANGING FORM THE
MID 70S IN THE NORTHWEST MOUNTAINS TO THE LOW 80S ACROSS THE LOWER
SUSQUEHANNA.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
HIGH PRESSURE WILL BE IN CONTROL ACROSS MOST OF THE AREA THIS
WEEKEND...AND PROVIDE GENERALLY FAIR WEATHER WITH SLIGHTLY BELOW
TO NEAR-AVERAGE TEMPS. THE NEXT COLD FRONT IS FCST TO ARRIVE ON
MONDAY BEFORE ANOTHER PUSH OF COOLER AND DRIER AIR FOR TUESDAY.
THE DAY2-3 FRONTAL BOUNDARY WILL LINGER OFF THE NORTHEAST/MID-
ATLC COAST THIS WEEKEND AND MAY TRY TO DRIFT WWD WITH TIME. MODEL
CONSENSUS HAS PUSHED N-S PCPN AXIS FARTHER OFF THE COAST AND
THEREFORE WILL ONLY KEEP SCHC POPS ACROSS THE FAR ERN ZONES ON
SUNDAY.
&&
.AVIATION /04Z THURSDAY THROUGH MONDAY/...
SCATTERED SHOWERS CONTINUE TO MOVE THROUGH CENTRAL PA OVER THE
NEXT FEW HOURS...HOWEVER CIGS AND VSBYS AT TAF SITES SHOULD REMAIN
VFR.
LLWS WAS INCLUDED TONIGHT ACROSS JUST THE NORTHWESTERN MTN TAF
SITES - KBFD AND WILL FADE BY 07Z.
AS THE GRADIENT WIND INCREASES FROM THE SE OVERNIGHT...THIS
SHOULD HELP WITH LIMITING THE FOG DEVELOPMENT EARLY THURSDAY
MORNING.
HOWEVER LATEST HRRR/SREF SHOWS CLOUD BANDS FORMING OVERNIGHT SO
THERE SHOULD BE PERIODS OF MVFR TO IFR CIGS AND VSBYS POSSIBLE
BETWEEN 07Z TO 13Z. TIMING AND INTENSITY OF THE PATCHY DENSE
FOG/MIST AND LOW STRATOCU WILL BE THE FORECAST PROBLEM THROUGH
15Z. CLEARING SKIES OVER THE NORTH...RECENT RAINFALL AND LOWERING
STRATOCU ELSEWHERE SHOULD ALLOW FOR IFR AT BFD...JST...AOO...UNV
POSSIBLE. IPT MDT AND LNS ARE LESS LIKELY...WITH MVFR POSSIBLE.
EXPECT CONDITIONS TO IMPROVE SLOWLY WITH SOME MVFR REDUCING CIGS
POSSIBLE UNTIL AROUND 15Z.
A COLD FRONT SLIDING SLOWLY EAST ACROSS THE TERMINALS LATE
THURSDAY AND INTO EARLY FRIDAY WILL RESULT IN SOME SHOWERS AND
THUNDERSTORMS LATER THURSDAY AFTERNOON AND INTO EARLY FRIDAY
MORNING.
OUTLOOK...
THU...AM LOW CIGS/FOG POSS. SCT/NUMEROUS PM TSRA IMPACTS POSSIBLE.
FRI-SUN...NO SIG WX EXPECTED.
&&
.HYDROLOGY...
AN ELEVATED RISK OF VERY LOCALIZED FLASH FLOODING WILL EXIST THURSDAY
INTO THURSDAY NIGHT...MAINLY ACROSS THE EASTERN HALF OF PENN.
NARROW...NORTH-SOUTH BANDS OF HEAVY TO LOCALLY EXCESSIVE RAINFALL
ARE POSSIBLE WHICH MAY RESULT IN SOME FLASH FLOODING AND SHARP
RISES ON SMALL STREAMS/CREEKS. AT THIS TIME CONFIDENCE IS LOW IN
DETERMINING THE EXACT LOCATION OF THE HEAVIEST RAIN BUT THE LARGE
SCALE PATTERN AND ATMOS MOISTURE IS SUPPORTIVE OF 2+ INCH AMOUNTS
IN A SHORT DURATION.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE/LAMBERT
NEAR TERM...LA CORTE/LAMBERT
SHORT TERM...LAMBERT
LONG TERM...GARTNER/STEINBUGL
AVIATION...LAMBERT/CERU
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1018 PM EDT WED AUG 19 2015
.SYNOPSIS...
A COLD FRONT WILL MOVE SLOWLY THROUGH THE REGION THURSDAY INTO
THURSDAY NIGHT. LOWER HUMIDITY AND MAINLY DRY WEATHER WILL RETURN
TO MOST OF CENTRAL PA FRIDAY THROUGH THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
SHOWER ACTIVITY IS FADING WITH THE LOSS OF HEATING AND INCREASED
STABILITY. THE HRRR CONTINUES WITH THE IDEA OF SCATTERED
ACTIVITY MEANDERING ABOUT FOR THE OVERNIGHT SO WHILE I LOWERED
POPS...I DID NOT ELIMINATE THE MENTION OF RAIN ALTOGETHER. IT DOES
LOOK LIKE MOST AREAS WILL REMAIN RAIN FREE FOR THE REST OF THE
NIGHT HOWEVER.
THE OVERNIGHT PERIOD WILL REMAIN WARM AND MUGGY WITH LOWS IN THE
UPPER 60S TO LOW 70S.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
AN INCREASE IN CYCLONIC FLOW ALOFT AHEAD OF IMPRESSIVE MID LEVEL
CYCLONE FOR THIS TIME OF YEAR OVER THE UPPER GREAT LAKES REGION...
AND STRENGTHENING OF THE S-SE LLJ SHOULD RESULT IN AN INCREASE IN
SHOWER ACTIVITY ONCE AGAIN AFTER 12Z. A BLEND OF NEAR AND SHORT
TERM MODEL QPF TARGETS AN AXIS OF PCPN FROM THE SRN DELMARVA INTO
ERN PA WHICH MAY BE ENHANCED BY SSERLY FEED OF ATLANTIC
MOISTURE.
THE SFC COLD FRONT IS FORECASTED TO MOVE THROUGH THE CENTRAL
MOUNTAINS BY LATE AFTERNOON AND THE SUSQUEHANNA VALLEY THURSDAY
EVENING.
THE BEST SHEAR VALUES LOOK TO BE NORTH AND WEST OF THE SPINE OF
THE APPALACHIANS WITH THE SREF INDICATING A 70% PROBABILITY OF
SHEAR GREATER THAN 30 KTS IN THE NORTHWEST MOUNTAINS AND WESTERN
LAURELS LATE TOMORROW AFTERNOON. SURFACE CAPE VALUES WILL RANGE
FROM 1000 TO 2000 J/KG IN THE AFTERNOON.
THE BIGGEST CONCERN FOR THURSDAY IS THE THREAT FOR FLASH FLOODING
AS WE HAVE ANOMALOUSLY HIGH PWATS BETWEEN TWO AND THREE STANDARD
DEVIATIONS ABOVE NORMAL. RFC FFG MOSAIC INDICATES THAT AMTS ARE
HIGHEST /2 TO 4 INCHES OVER A 6-HOUR PERIOD/ WHERE WE EXPECT THE
HEAVIEST RAIN TO FALL - ACROSS THE ERN HALF OF THE CWA THURSDAY
AFTERNOON AND NIGHT.
MODEL/ENSEMBLE CONSENSUS QPF STILL POINTS TWD JUST UNDER ONE INCH
ACROSS THE WESTERN PART OF THE CWA...AND 1-1.5 INCHES ACROSS THE
EAST...WITH OBVIOUSLY SOME HIGHER NARROW-BANDED 2+ INCH TOTALS.
HIGH TEMPERATURES ON THURSDAY WILL REMAIN MILD RANGING FORM THE
MID 70S IN THE NORTHWEST MOUNTAINS TO THE LOW 80S ACROSS THE LOWER
SUSQUEHANNA.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
HIGH PRESSURE WILL BE IN CONTROL ACROSS MOST OF THE AREA THIS
WEEKEND...AND PROVIDE GENERALLY FAIR WEATHER WITH SLIGHTLY BELOW
TO NEAR-AVERAGE TEMPS. THE NEXT COLD FRONT IS FCST TO ARRIVE ON
MONDAY BEFORE ANOTHER PUSH OF COOLER AND DRIER AIR FOR TUESDAY.
THE DAY2-3 FRONTAL BOUNDARY WILL LINGER OFF THE NORTHEAST/MID-
ATLC COAST THIS WEEKEND AND MAY TRY TO DRIFT WWD WITH TIME. MODEL
CONSENSUS HAS PUSHED N-S PCPN AXIS FARTHER OFF THE COAST AND
THEREFORE WILL ONLY KEEP SCHC POPS ACROSS THE FAR ERN ZONES ON
SUNDAY.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
SCATTERED SHOWERS CONTINUE TO MOVE THROUGH CENTRAL PA OVER THE
NEXT FEW HOURS...HOWEVER CIGS AND VSBYS AT TAF SITES SHOULD REMAIN
VFR...THE SOLE EXCEPTION WILL BE LNS WHICH COULD SEE MVFR CIGS AND
VSBYS IN -RA BETWEEN 01Z AND 03Z.
LLWS WAS INCLUDED TONIGHT ACROSS JUST THE NORTHWESTERN MTN TAF
SITES - KBFD.
AS THE GRADIENT WIND INCREASES FROM THE SE OVERNIGHT...THIS
SHOULD HELP WITH LIMITING THE FOG DEVELOPMENT EARLY THURSDAY
MORNING.
HOWEVER LATEST HRRR/SREF SHOWS CLOUD BANDS FORMING OVERNIGHT SO
THERE SHOULD BE PERIODS OF MVFR TO IFR CIGS AND VSBYS POSSIBLE
BETWEEN 07Z TO 13Z.
EXPECT CONDITIONS TO IMPROVE SLOWLY WITH SOME MVFR REDUCING CIGS
POSSIBLE UNTIL AROUND 15Z.
A COLD FRONT SLIDING SLOWLY EAST ACROSS THE TERMINALS LATE
THURSDAY AND INTO EARLY FRIDAY WILL RESULT IN SOME SHOWERS AND
THUNDERSTORMS LATER THURSDAY AFTERNOON AND INTO EARLY FRIDAY
MORNING.
OUTLOOK...
THU...AM LOW CIGS/FOG POSS. SCT/NUMEROUS PM TSRA IMPACTS POSSIBLE.
FRI-SUN...NO SIG WX EXPECTED.
&&
.HYDROLOGY...
AN ELEVATED RISK OF VERY LOCALIZED FLASH FLOODING WILL EXIST THURSDAY
INTO THURSDAY NIGHT...MAINLY ACROSS THE EASTERN HALF OF PENN.
NARROW...NORTH-SOUTH BANDS OF HEAVY TO LOCALLY EXCESSIVE RAINFALL
ARE POSSIBLE WHICH MAY RESULT IN SOME FLASH FLOODING AND SHARP
RISES ON SMALL STREAMS/CREEKS. AT THIS TIME CONFIDENCE IS LOW IN
DETERMINING THE EXACT LOCATION OF THE HEAVIEST RAIN BUT THE LARGE
SCALE PATTERN AND ATMOS MOISTURE IS SUPPORTIVE OF 2+ INCH AMOUNTS
IN A SHORT DURATION.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE/LAMBERT
NEAR TERM...LA CORTE/LAMBERT
SHORT TERM...LAMBERT
LONG TERM...GARTNER/STEINBUGL
AVIATION...LAMBERT/CERU
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
750 AM EDT TUE AUG 18 2015
.SYNOPSIS...
A WEAKENING UPPER AIR DISTURBANCE WILL SLIDE THROUGH THE AREA
TODAY. A STRONGER DISTURBANCE WILL MOVE INTO AND THROUGH THE
REGION LATER WEDNESDAY AND THURSDAY. DRIER CONDITIONS WILL RETURN
FOR THE END OF THE WEEK AND WEEKEND AS TEMPERATURES FALL BACK TO
NEAR NORMAL.
&&
.NEAR TERM /THROUGH TONIGHT/...
RADAR SHOWS AN MCS MOVING SLOWLY NORTH INTO FAR SWRN PA...WITH
THE EASTERN EXTENT OF THE RAIN EXTENDING FROM THE SOUTHERN LAURELS
DOWN INTO WEST VA. THIS IS ASSOCIATED WITH A SHEARING OUT
SHORTWAVE AND AN AREA OF WARM ADVECTION AND LOW LEVEL CONVERGENCE.
THE HRRR AND RAP CONFINE THE SHOWERS TO MY FAR WESTERN ZONES
THROUGH LATE MORNING BEFORE GENERATING MORE SPOTTY SCATTERED
SHOWERS AND STORMS FOR THE AFTERNOON.
WHAT`S LEFT OF THE WEAKENING SHORTWAVE WILL TRAVERSE THE REGION
TODAY WITH THE BEST CHANCE FOR RAIN BEING OVER THE WEST...AND
CHANCES DIMINISHING OVER CENTRAL AND EASTERN AREAS. WOULD NOT BE
SURPRISED IF THE LOWER SUSQ SEES MUCH OF ANY RAIN AT ALL.
IT WILL BE ANOTHER WARM-HUMID DAY...BUT THE CLOUDS AND SCATTERED
SHOWERS WILL LIKELY SHAVE A FEW DEG OFF YESTERDAYS READINGS.
TIMING THE SHORTWAVE IN THE MODEL GUIDANCE SUGGESTS WE WILL
EXPERIENCE A BIT OF A LULL IN THE SHOWERY CONDITIONS
OVERNIGHT...ESPECIALLY THE SECOND HALF OF THE OVERNIGHT. ANOTHER
MUGGY NIGHT IS IN STORE WITH LOWS GENERALLY IN THE MID 60S TO
LOWER 70S...SOME 10-15 DEF ABOVE NORMAL.
&&
.SHORT TERM /WEDNESDAY/...
AFTER A SHORT PERIOD OF WEAK RIDGING ALOFT TONIGHT IN THE WAKE OF
THE DEPARTING SHORTWAVE...WEDNESDAY WILL FEATURE HEIGHTS ALOFT
BEGINNING TO FALL ONCE AGAIN...ESPECIALLY THE LAST PART OF THE
DAY AS THE LARGE ANOMALOUSLY DEEP TROUGH OVER THE UPPER MIDWEST
BEGINS TO MOVE INTO THE WESTERN GR LAKES AND SOUTHERN CANADA. THE
CHANCES FOR SHOWERS WILL ONCE AGAIN BE ON THE RISE AS ANOTHER SHOT
OF DEEP MOISTURE ADVECTS INTO THE AREA ON A STRENGTHENING DEEP
SOUTHWESTERLY FLOW. THE GEFS SHOWS THE PWATS INCREASING TO 2-3 STD
DEV ABOVE NORMAL DURING THE DAY WED. THOUGH I PRETTY MUCH
BROADBRUSHED THE CHANCE FOR SCATTERED SHOWERS AND
STORMS...THINKING IS THE AFTERNOON WILL SEE THE BEST CHANCE OF
RAIN OVER MOST OF MY AREA.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THERE IS PRETTY GOOD AGREEMENT THAT THE ANOMALOUSLY DEEP SYSTEM
TO OUR WEST WILL QUICKLY SHEAR OUT AND BRING THE MAIN SURGE OF
PRECIP/FORCING INTO THE LOCAL AREA THURSDAY.
I HAVE SOME CONCERN FOR LOCALIZED HEAVY RAINS DEVELOPING AS THE
SHORT RANGE MODELS SUGGEST THE FRONT WILL SLOW DOWN AS THE UPPER
JET SURGES INTO SOUTHERN CANADA. STRONG LOW LEVEL FRONTOGENETIC
FORCING IS INDICATED AS THE WAVY FRONT MOVES SLOWLY THROUGH
CENTRAL AND EASTERN AREAS. LATEST ENSEMBLES SHOW A SMALL PROB OF
1" OR MORE AMOUNTS OVER CENTRAL AND EASTERN AREAS THURSDAY
AFTERNOON AND EVENING...WITH THE ECMWF EVEN HINTING THAT AN AREA
OF HEAVY RAIN COULD LINGER INTO THURSDAY NIGHT OVER MOST OF MY
EASTERN ZONES.
GUIDANCE SUGGESTS THE FRONT IS BASICALLY EAST OF THE FORECAST AREA
BY FRIDAY...WITH PERHAPS FAR EASTERN AREAS STILL SEEING A
LINGERING SHOWER THREAT. BUT DRIER AIR MOVING IN BEHIND THE FRONT
LOOKS LIKE A HIGH CONFIDENCE FORECAST FOR FRIDAY AND
SATURDAY...BEFORE THINGS GET POTENTIALLY MUDDY ONCE AGAIN FOR THE
END OF THE WEEKEND.
WEAK TROUGHING ALOFT AND THE SURFACE HIGH SLIDING OFF THE NEW
ENGLAND COAST COULD CONSPIRE TO BRING THE CHANCES FOR SOME
SHOWERS...OR MAYBE EVEN LOW CLOUDS AND LIGHT RAIN OR DRIZZLE AS
DEPICTED IN THE OPERATIONAL GFS BACK INTO THE AREA FOR SUNDAY. I
KEPT THE CHANCES LOW...BUT HAVE LITTLE CONFIDENCE IN THE FORECAST
THAT FAR OUT.
IT WILL REMAIN WARM WITH DAILY HIGHS AVERAGING ABOVE NORMAL
THROUGHOUT THE PERIOD.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
12Z TAFS SENT.
DID ADJUST SOME...BULK OF SHOWERS AND STORMS LOOKS
TO BE LIFTING NW OF OUR AREA.
EXPECT MORE IN THE WAY OF FOG TONIGHT...AS DEWPOINTS
COME UP SOME.
EARLIER DISCUSSION BELOW.
SOME SHOWERS AND THUNDERSTORMS TODAY...AS A WEAK SYSTEM LIFTS
NORTHWARD. FAR SE AREAS SUCH AS LNS...MAY SE LITTLE IF ANY RAIN
BEFORE LATE AFT.
MORE IN THE WAY OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
ON WED INTO THU...AS A RATHER DEEP SYSTEM LIFTS NE TOWARD THE
LAKES.
HOWEVER...TREND WILL BE FOR SYSTEMS TO LIFT NW OF OUR AREA.
THIS WILL TREND TO TAPER THE AMT OF COLD AIR BEHIND THE
FRONTS AND ANY STORMS THAT FORM ALONG THE FRONT.
OUTLOOK...
WED...ISOLD PM TSRA IMPACTS POSS W MTNS.
THU...AM LOW CIGS/FOG POSS. SCT/NUMEROUS PM TSRA IMPACTS
POSSIBLE.
FRI-SAT...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...LA CORTE
AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
544 AM EDT TUE AUG 18 2015
.SYNOPSIS...
A WEAKENING UPPER AIR DISTURBANCE WILL SLIDE THROUGH THE AREA
TODAY. A STRONGER DISTURBANCE WILL MOVE INTO AND THROUGH THE
REGION LATER WEDNESDAY AND THURSDAY. DRIER CONDITIONS WILL RETURN
FOR THE END OF THE WEEK AND WEEKEND AS TEMPERATURES FALL BACK TO
NEAR NORMAL.
&&
.NEAR TERM /THROUGH TONIGHT/...
RADAR SHOWS AN MCS MOVING SLOWLY NORTH INTO FAR SWRN PA...WITH
THE EASTERN EXTENT OF THE RAIN EXTENDING FROM THE SOUTHERN LAURELS
DOWN INTO WEST VA. THIS IS ASSOCIATED WITH A SHEARING OUT
SHORTWAVE AND AN AREA OF WARM ADVECTION AND LOW LEVEL CONVERGENCE.
THE HRRR AND RAP CONFINE THE SHOWERS TO MY FAR WESTERN ZONES
THROUGH LATE MORNING BEFORE GENERATING MORE SPOTTY SCATTERED
SHOWERS AND STORMS FOR THE AFTERNOON.
WHAT`S LEFT OF THE WEAKENING SHORTWAVE WILL TRAVERSE THE REGION
TODAY WITH THE BEST CHANCE FOR RAIN BEING OVER THE WEST...AND
CHANCES DIMINISHING OVER CENTRAL AND EASTERN AREAS. WOULD NOT BE
SURPRISED IF THE LOWER SUSQ SEES MUCH OF ANY RAIN AT ALL.
IT WILL BE ANOTHER WARM-HUMID DAY...BUT THE CLOUDS AND SCATTERED
SHOWERS WILL LIKELY SHAVE A FEW DEG OFF YESTERDAYS READINGS.
TIMING THE SHORTWAVE IN THE MODEL GUIDANCE SUGGESTS WE WILL
EXPERIENCE A BIT OF A LULL IN THE SHOWERY CONDITIONS
OVERNIGHT...ESPECIALLY THE SECOND HALF OF THE OVERNIGHT. ANOTHER
MUGGY NIGHT IS IN STORE WITH LOWS GENERALLY IN THE MID 60S TO
LOWER 70S...SOME 10-15 DEF ABOVE NORMAL.
&&
.SHORT TERM /WEDNESDAY/...
AFTER A SHORT PERIOD OF WEAK RIDGING ALOFT TONIGHT IN THE WAKE OF
THE DEPARTING SHORTWAVE...WEDNESDAY WILL FEATURE HEIGHTS ALOFT
BEGINNING TO FALL ONCE AGAIN...ESPECIALLY THE LAST PART OF THE
DAY AS THE LARGE ANOMALOUSLY DEEP TROUGH OVER THE UPPER MIDWEST
BEGINS TO MOVE INTO THE WESTERN GR LAKES AND SOUTHERN CANADA. THE
CHANCES FOR SHOWERS WILL ONCE AGAIN BE ON THE RISE AS ANOTHER SHOT
OF DEEP MOISTURE ADVECTS INTO THE AREA ON A STRENGTHENING DEEP
SOUTHWESTERLY FLOW. THE GEFS SHOWS THE PWATS INCREASING TO 2-3 STD
DEV ABOVE NORMAL DURING THE DAY WED. THOUGH I PRETTY MUCH
BROADBRUSHED THE CHANCE FOR SCATTERED SHOWERS AND
STORMS...THINKING IS THE AFTERNOON WILL SEE THE BEST CHANCE OF
RAIN OVER MOST OF MY AREA.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THERE IS PRETTY GOOD AGREEMENT THAT THE ANOMALOUSLY DEEP SYSTEM
TO OUR WEST WILL QUICKLY SHEAR OUT AND BRING THE MAIN SURGE OF
PRECIP/FORCING INTO THE LOCAL AREA THURSDAY.
I HAVE SOME CONCERN FOR LOCALIZED HEAVY RAINS DEVELOPING AS THE
SHORT RANGE MODELS SUGGEST THE FRONT WILL SLOW DOWN AS THE UPPER
JET SURGES INTO SOUTHERN CANADA. STRONG LOW LEVEL FRONTOGENETIC
FORCING IS INDICATED AS THE WAVY FRONT MOVES SLOWLY THROUGH
CENTRAL AND EASTERN AREAS. LATEST ENSEMBLES SHOW A SMALL PROB OF
1" OR MORE AMOUNTS OVER CENTRAL AND EASTERN AREAS THURSDAY
AFTERNOON AND EVENING...WITH THE ECMWF EVEN HINTING THAT AN AREA
OF HEAVY RAIN COULD LINGER INTO THURSDAY NIGHT OVER MOST OF MY
EASTERN ZONES.
GUIDANCE SUGGESTS THE FRONT IS BASICALLY EAST OF THE FORECAST AREA
BY FRIDAY...WITH PERHAPS FAR EASTERN AREAS STILL SEEING A
LINGERING SHOWER THREAT. BUT DRIER AIR MOVING IN BEHIND THE FRONT
LOOKS LIKE A HIGH CONFIDENCE FORECAST FOR FRIDAY AND
SATURDAY...BEFORE THINGS GET POTENTIALLY MUDDY ONCE AGAIN FOR THE
END OF THE WEEKEND.
WEAK TROUGHING ALOFT AND THE SURFACE HIGH SLIDING OFF THE NEW
ENGLAND COAST COULD CONSPIRE TO BRING THE CHANCES FOR SOME
SHOWERS...OR MAYBE EVEN LOW CLOUDS AND LIGHT RAIN OR DRIZZLE AS
DEPICTED IN THE OPERATIONAL GFS BACK INTO THE AREA FOR SUNDAY. I
KEPT THE CHANCES LOW...BUT HAVE LITTLE CONFIDENCE IN THE FORECAST
THAT FAR OUT.
IT WILL REMAIN WARM WITH DAILY HIGHS AVERAGING ABOVE NORMAL
THROUGHOUT THE PERIOD.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
09Z TAFS SENT.
SOME MINOR ADJUSTMENTS MADE TO THE 09Z TAFS.
SOME SHOWERS AND THUNDERSTORMS TODAY...AS A WEAK SYSTEM LIFTS
NORTHWARD. FAR SE AREAS SUCH AS LNS...MAY SE LITTLE IF ANY RAIN
BEFORE LATE AFT.
MORE IN THE WAY OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
ON WED INTO THU...AS A RATHER DEEP SYSTEM LIFTS NE TOWARD THE
LAKES.
HOWEVER...TREND WILL BE FOR SYSTEMS TO LIFT NW OF OUR AREA.
THIS WILL TREND TO TAPER THE AMT OF COLD AIR BEHIND THE
FRONTS AND ANY STORMS THAT FORM ALONG THE FRONT.
OUTLOOK...
WED...ISOLD PM TSRA IMPACTS POSS W MTNS.
THU...AM LOW CIGS/FOG POSS. SCT/NUMEROUS PM TSRA IMPACTS
POSSIBLE.
FRI-SAT...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...LA CORTE
AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
513 AM EDT TUE AUG 18 2015
.SYNOPSIS...
A WEAKENING UPPER AIR DISTURBANCE WILL SLIDE THROUGH THE AREA
TODAY. A STRONGER DISTURBANCE WILL MOVE INTO AND THROUGH THE
REGION LATER WEDNESDAY AND THURSDAY. DRIER CONDITIONS WILL RETURN
FOR THE END OF THE WEEK AND WEEKEND AS TEMPERATURES FALL BACK TO
NEAR NORMAL.
&&
.NEAR TERM /THROUGH TONIGHT/...
RADAR SHOWS AN MCS MOVING SLOWLY NORTH INTO FAR SWRN PA...WITH
THE EASTERN EXTENT OF THE RAIN EXTENDING FROM THE SOUTHERN LAURELS
DOWN INTO WEST VA. THIS IS ASSOCIATED WITH A SHEARING OUT
SHORTWAVE AND AN AREA OF WARM ADVECTION AND LOW LEVEL CONVERGENCE.
THE HRRR AND RAP CONFINE THE SHOWERS TO MY FAR WESTERN ZONES
THROUGH LATE MORNING BEFORE GENERATING MORE SPOTTY SCATTERED
SHOWERS AND STORMS FOR THE AFTERNOON.
WHAT`S LEFT OF THE WEAKENING SHORTWAVE WILL TRAVERSE THE REGION
TODAY WITH THE BEST CHANCE FOR RAIN BEING OVER THE WEST...AND
CHANCES DIMINISHING OVER CENTRAL AND EASTERN AREAS. WOULD NOT BE
SURPRISED IF THE LOWER SUSQ SEES MUCH OF ANY RAIN AT ALL.
IT WILL BE ANOTHER WARM-HUMID DAY...BUT THE CLOUDS AND SCATTERED
SHOWERS WILL LIKELY SHAVE A FEW DEG OFF YESTERDAYS READINGS.
TIMING THE SHORTWAVE IN THE MODEL GUIDANCE SUGGESTS WE WILL
EXPERIENCE A BIT OF A LULL IN THE SHOWERY CONDITIONS
OVERNIGHT...ESPECIALLY THE SECOND HALF OF THE OVERNIGHT. ANOTHER
MUGGY NIGHT IS IN STORE WITH LOWS GENERALLY IN THE MID 60S TO
LOWER 70S...SOME 10-15 DEF ABOVE NORMAL.
&&
.SHORT TERM /WEDNESDAY/...
AFTER A SHORT PERIOD OF WEAK RIDGING ALOFT TONIGHT IN THE WAKE OF
THE DEPARTING SHORTWAVE...WEDNESDAY WILL FEATURE HEIGHTS ALOFT
BEGINNING TO FALL ONCE AGAIN...ESPECIALLY THE LAST PART OF THE
DAY AS THE LARGE ANOMALOUSLY DEEP TROUGH OVER THE UPPER MIDWEST
BEGINS TO MOVE INTO THE WESTERN GR LAKES AND SOUTHERN CANADA. THE
CHANCES FOR SHOWERS WILL ONCE AGAIN BE ON THE RISE AS ANOTHER SHOT
OF DEEP MOISTURE ADVECTS INTO THE AREA ON A STRENGTHENING DEEP
SOUTHWESTERLY FLOW. THE GEFS SHOWS THE PWATS INCREASING TO 2-3 STD
DEV ABOVE NORMAL DURING THE DAY WED. THOUGH I PRETTY MUCH
BROADBRUSHED THE CHANCE FOR SCATTERED SHOWERS AND
STORMS...THINKING IS THE AFTERNOON WILL SEE THE BEST CHANCE OF
RAIN OVER MOST OF MY AREA.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THERE IS PRETTY GOOD AGREEMENT THAT THE ANOMALOUSLY DEEP SYSTEM
TO OUR WEST WILL QUICKLY SHEAR OUT AND BRING THE MAIN SURGE OF
PRECIP/FORCING INTO THE LOCAL AREA THURSDAY.
I HAVE SOME CONCERN FOR LOCALIZED HEAVY RAINS DEVELOPING AS THE
SHORT RANGE MODELS SUGGEST THE FRONT WILL SLOW DOWN AS THE UPPER
JET SURGES INTO SOUTHERN CANADA. STRONG LOW LEVEL FRONTOGENETIC
FORCING IS INDICATED AS THE WAVY FRONT MOVES SLOWLY THROUGH
CENTRAL AND EASTERN AREAS. LATEST ENSEMBLES SHOW A SMALL PROB OF
1" OR MORE AMOUNTS OVER CENTRAL AND EASTERN AREAS THURSDAY
AFTERNOON AND EVENING...WITH THE ECMWF EVEN HINTING THAT AN AREA
OF HEAVY RAIN COULD LINGER INTO THURSDAY NIGHT OVER MOST OF MY
EASTERN ZONES.
GUIDANCE SUGGESTS THE FRONT IS BASICALLY EAST OF THE FORECAST AREA
BY FRIDAY...WITH PERHAPS FAR EASTERN AREAS STILL SEEING A
LINGERING SHOWER THREAT. BUT DRIER AIR MOVING IN BEHIND THE FRONT
LOOKS LIKE A HIGH CONFIDENCE FORECAST FOR FRIDAY AND
SATURDAY...BEFORE THINGS GET POTENTIALLY MUDDY ONCE AGAIN FOR THE
END OF THE WEEKEND.
WEAK TROUGHING ALOFT AND THE SURFACE HIGH SLIDING OFF THE NEW
ENGLAND COAST COULD CONSPIRE TO BRING THE CHANCES FOR SOME
SHOWERS...OR MAYBE EVEN LOW CLOUDS AND LIGHT RAIN OR DRIZZLE AS
DEPICTED IN THE OPERATIONAL GFS BACK INTO THE AREA FOR SUNDAY. I
KEPT THE CHANCES LOW...BUT HAVE LITTLE CONFIDENCE IN THE FORECAST
THAT FAR OUT.
IT WILL REMAIN WARM WITH DAILY HIGHS AVERAGING ABOVE NORMAL THROUGHOUT
THE PERIOD.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
SOME SHOWERS TODAY...AS A WEAK SYSTEM LIFT NORTHWARD. FAR SE
AREAS SUCH AS LNS...MAY SE LITTLE IF ANY RAIN.
MORE IN THE WAY OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
ON WED INTO THU...AS A RATHER DEEP SYSTEM LIFTS NE TOWARD THE
LAKES.
HOWEVER...TREND WILL BE FOR SYSTEMS TO LIFT NW OF OUR AREA.
THIS WILL TREND TO TAPER THE AMT OF COLD AIR BEHIND THE
FRONTS AND ANY STORMS THAT FORM ALONG THE FRONT.
PREVIOUS DISCUSSION BELOW.
A MCLEAR SKY AND NEARLY CALM WIND SHOULD PROMOTE PATCHY VALLEY
FOG TOWARDS DAWN ACROSS CENTRAL PA. CLIMATOLOGY SUGGESTS A PERIOD
OF IFR CONDS ARE POSSIBLE LATE TONIGHT AT KBFD/KIPT...BUT
INCREASING CLOUDS AT KBFD COULD LIMIT RAD COOLING AND FOG
POTENTIAL. ELSEWHERE...LATEST LAMP/NAM GUIDANCE...COMBINED WITH A
COMPARISON OF DWPT DEPRESSIONS FROM LAST EVENING...SUGGEST A BRIEF
MVFR VIS REDUCTION IS LIKELY ARND DAWN AT KUNV/KAOO/KLNS...SIMILAR
TO WHAT OCCURRED THIS AM.
A TROUGH OF LOW OF PRES LIFTING OUT OF THE OHIO VALLEY WILL SPREAD
SHOWERS AND POSS TSRA INTO THE AREA ON TUESDAY. ALTHOUGH VFR CONDS
WILL PREDOMINATE...BRIEF VIS REDUCTIONS ARE POSSIBLE IN ANY
SHOWERS OR TSRA. LATEST MDL TIMING SUGGEST THE SHOWERS WILL
OVERSPREAD THE W MTNS DURING LATE AM...AND REACH THE EASTERN HALF
OF PA DURING THE PM HOURS.
OUTLOOK...
WED...ISOLD PM TSRA IMPACTS POSS W MTNS.
THU...AM LOW CIGS/FOG POSS. SCT/NUMEROUS PM TSRA IMPACTS
POSSIBLE.
FRI-SAT...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...LA CORTE
AVIATION...FITZGERALD/MARTIN
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
808 PM EDT WED AUG 19 2015
.SYNOPSIS...
A WEAK FRONT WILL APPROACH THE AREA ON THURSDAY...PRECEDED BY
SHOWERS AND THUNDERSTORMS. SOME DRYING IS EXPECTED OVER THE WEEKEND.
ANOTHER WEAK FRONT APPROACHES OUR AREA EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 750 PM WED...THUNDERSHOWER ACTIVITY IS BEGINNING TO SETTLE
DOWN AS EXPECTED WITH THE ONLY HEAVY STORM IN THE AREA CONTINUING
OVER UNION COUNTY WITH CONTINUED MODERATE TO HEAVY RAINFALL FOR THE
NEXT HOUR OR TWO. ALL BUT LIGHT ACTIVITY IS EXPECTED TO END IN THE
NEXT 2 OR 3 HOURS. SOME AREAS HAVE RECEIVED VERY HEAVY RAINFALL
TODAY AND YESTERDAY WHICH IS LEADING TO SIGNIFICANT LOCALIZED
FLOODING. CHANCES FOR MORE RAIN CONTINUE TOMORROW...THOUGH THE
PROBABILITY OF PRECIP. IS NOT AS HIGH AS WAS SEEN TODAY.
AS OF 510 PM WED...UPDATED FORECAST TO CONCENTRATE PRECIPITATION TO
EASTERN PARTS OF THE CWA PER RADAR TRENDS AND HRRR GUIDANCE. RADAR
HAS HAD HEAVIEST COVERAGE OF THUNDERSTORMS MOVING EASTWARD WITH SOME
RESIDUAL ACTIVITY ELSEWHERE. HEAVIER STORMS OVER EASTERN PARTS OF
THE CWA AGREES WITH HIGHER CAPE ANALYSIS IN THAT AREA. RAINFALL
AMOUNTS WILL CONTINUE TO BE GENEROUS...GIVEN HIGH PRECIPITABLE
WATER. SHOWERS WILL BEGIN TO TAPER AFTER 3Z THIS EVENING.
AS OF 230 PM WED...RADAR CONTINUES TO SHOW INCREASING COVERAGE AND
EXPECT NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS THE AREA THROUGH
THE AFTERNOON. SOME MORE STRATIFORM TYPE PRECIP WITH EMBEDDED
THUNDER MAY LINGER INTO THE EVENING HOURS OVER EASTERN AREAS. SPC
MESOANAL SHOWING CAPES IN THE 2000-3000J/KG RANGE OUTSIDE THE
MOUNTAINS. ALSO...THE DCAPE HIGHER TODAY THAN PREVIOUS DAYS NOW
HAVING INCREASED TO OVER 1000J EASTERN AREAS. HENCE...SEVERE STORM
CHANCES HIGHER THIS AFTERNOON AND WE SHOULD SEE SEVERAL PULSE SEVERE
STORMS. THE SEVERE THREAT WILL BE ALONG SIDE THE LOCALIZED HYDRO
THREAT.
IN REGARD TO THE BIG PICTURE...A VORT MAX IS FORECAST TO MOVE ACROSS
THE AREA DURING THE LATE AFTERNOON AND EVENING HOURS WHICH IS THE
PRIMARY TRIGGER OF THE NUMEROUS SHOWERS AND STORMS. NVA BEHIND THIS
FEATURE SHOULD RESULT IN A LULL IN PRECIP COVERAGE DURING THE
OVERNIGHT HOURS. MINIMUM TEMPS ARE EXPECTED TO BE ABOUT A CATEGORY
ABOVE CLIMO.
ON THURSDAY...A DEEP UPPER TROUGH SWINGING THROUGH THE GREAT LAKES
WILL PUSH A COLD FRONT SOUTHEASTWARD AND IT IS FORECAST TO REACH THE
MOUNTAINS DURING THE AFTERNOON. WITH DEEP LAYER MOISTURE STILL IN
PLACE...THERE STILL SHOULD BE DECENT COVERAGE OF SHOWERS AND
THUNDERSTORMS IN THE MOUNTAINS. HOWEVER EAST OF THE MOUNTAINS...WITH
FLOW BECOMING MORE ZONAL/DOWNSLOPE THE COVERAGE SHOULD BE SCT. MODEL
FORECAST SOUNDINGS ALSO INDICATE LESS CAPE...SO SEVERE THREAT
APPEARS ON THE LOW END. MAX TEMPS WILL BE NEAR TO CLIMO.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM EDT WEDNESDAY...THE SHORT TERM FCST PERIOD INITIALIZES
THURSDAY EVENING AMIDST AN ONGOING COLD FRONTAL INTRUSION.
THE UPPER PATTERN WILL BE HIGHLIGHTED BY A DEEP NEGATIVELY TILTED
LONGWAVE TROF EJECTING THROUGH THE GREAT LAKES WHILE BROAD RIDGING
PREVAILS OVER THE DEEP SOUTH AND EASTERN GULF. AS STATED ABOVE...A
COLD FRONT WILL BE WORKING ITS WAY INTO/THROUGH THE NC HIGH TERRAIN
BY THURSDAY EVENING WITH DEEP SOUTHWESTERLY FLOW PREVAILING OUT
AHEAD. IN RESPONSE...EXPECTING ONGOING CONVECTION IN THE WARM
SECTOR AT FCST INITIALIZATION POSSIBLY AIDED BY ENHANCED SHEARING
AND VORT ADVECTION ALOFT. SHORT TERM GUIDANCE IS NOW IN BETTER
AGREEMENT WITH REGARDS TO THE TRACK/DEPTH OF THE FRONTAL PASSAGE
WITH BOTH THE GFS/NAM ALONG WITH THE ECMWF PUSHING THE BOUNDARY
SOUTH OF THE CWFA...LIKELY WASHING OUT OVER THE LOWCOUNTRY/MIDLANDS
BY MID MORNING FRIDAY.
BROAD SFC HIGH PRESSURE IS FCST TO ADVECT IN FROM THE MIDWEST
INTO THE OHIO VALLEY JUST BEHIND THE FRONT...BEFORE SLIDING OVER
THE SOUTHERN/CENTRAL APPS LATER IN THE DAY. AS A RESULT...DRIER
NORTHERLY FLOW WILL WARRANT DECREASED PRECIPITATION POTENTIAL
AND PARTLY CLOUDY SKIES ACROSS MUCH OF WESTERN NC. DUE TO CLOSER
PROXIMITY TO ANY REMNANT FRONTAL MOISTURE...LOCATIONS ALONG AND
SOUTH OF THE I85 CORRIDOR WILL SEE SLIGHTLY HIGH PROBABILITIES AND
THUS PARTLY/MOSTLY CLOUDY SKIES. NEVERTHELESS...PROFILES ARE NOT
SUPPORTIVE OF ANY DEEP CONVECTION AT THIS TIME THEREFORE NOTHING
MORE THAN GARDEN VARIETY SHOWERS WITH PERHAPS A FEW RUMBLES OF
THUNDER ARE EXPECTED. SATURDAY IS SHAPING UP TO BE THE NICEST DAY
OF THE PERIOD WITH MODELS INDICATING FURTHER DRY AIR INTRUSION
AS THE ABOVE MENTIONED SURFACE RIDGE MOVES EAST OF THE APPS.
MOSGUIDE AND TO SOME EXTENT EVEN THE RAW NAM INDICATES DEWPOINTS
IN THE UPPER 50S ACROSS NORTHWEST NC INCREASING TO THE LOWER 60S
ALONG THE I85 CORRIDOR. THUS EXPECTING MOSTLY SUNNY TO PARTLY
CLOUDY SKIES AND TEMPERATURES A FEW DEGREES BELOW NORMAL ALLOWING
FOR A BEAUTIFUL MID/LATE AUGUST DAY. THAT SAID...NAM GUID DOES
FAVORS AT LEAST SOME CHANCE FOR LOW END DESTABILIZATION OVER THE
SOUTHWEST NC MOUNTAINS AND NORTHEAST GA...THEREFORE WILL INCLUDE
POPS TO ACCOUNT FOR SUCH WITH MAX HEATING ON SATURDAY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AT 230 PM EDT WEDNESDAY...ON SUNDAY AN UPPER RIDGE WILL BE OVER THE
WESTERN USA...WITH A MEAN TROUGH OVER THE EAST. THE PATTERN
AMPLIFIES SLIGHTLY INTO TUESDAY AS A CLOSED UPPER LOW CROSSES SOUTH
CENTRAL CANADA. THE PATTERN DEAMPLIFIES SLIGHTLY BY THURSDAY AS THE
CANADIAN LOW APPROACHES THE ATLANTIC....BY WHICH TIME SOME
PROGRESSION TAKES PLACE...AND THE UPPER TROUGH REACHES THE EASTERN
SEABOARD...WHILE THE RIDGE UPSTREAM CROSSES THE PLAINS AND EXTENDS
INTO THE GULF STATES.
AT THE SURFACE...SUNDAY STARTS OUT WITH HIGH PRESSURE ALONG THE
EASTERN SEABOARD...WITH A COLD FRONT UPSTREAM FORM THE GREAT LAKES
TO THE SOUTHERN PLAINS. THIS FRONT REACHES THE SOUTHERN APPALACHIANS
ON MONDAY...MOVING TO THE COASTAL PLAIN BY TUESDAY...WHERE IT STALLS
AND REMAINS INTO WEDNESDAY. OUR AREA CAN EXPECT AN ACTIVE PATTERN
AHEAD OF AND ALONG THE FRONT...WITH A DRYING TREND IN THE
WAKE OF THE FRONT. AT THIS TIME...PRECIPITATION AMOUNTS ARE NOT
EXPECTED TO BE EXCESSIVE AS THE FRONT DOES NOT STALL UNTIL EAST OF
OUR AREA. TEMPERATURES WILL RUN NEAR NORMAL.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AT KCLT...SOME THUNDERSTORMS OF DECREASING INTENSITY WILL REMAIN IN
THE AREA FOR THE NEXT FEW HOURS...WITH ACTIVITY ALL BUT CEASING BY
3Z. HIGH BOUNDARY LAYER MOISTURE AND TROPICAL-LIKE CONDITIONS ARE
EXPECTED TO RESULT IN SOME REDUCED VISIBILITY IN THE MORNING WITH
SOME POSSIBLE FOG. AS ALWAYS...THERE IS SOME UNCERTAINTY ABOUT
POSSIBLE MORNING FOG. CURRENT FORECAST HAS VISIBILITY DOWN TO
4SM...WHICH IS A COMPROMISE BETWEEN THE POSSIBILITIES RANGING FROM
10SM TO 1SM. THUNDERSTORMS ARE AGAIN POSSIBLE ON THURSDAY
AFTERNOON...THOUGH A BIT LESS PROBABLE THAN TODAY.
ELSEWHERE...THUNDERSTORM ACTIVITY HAS ENDED OR WILL SHORTLY END MOST
AREAS THIS EVENING WITH A GOOD CHANCE FOR MORE THUNDERSTORM ACTIVITY
THURSDAY AFTERNOON...WITH THE BEST CHANCE OVER THE MOUNTAINS.
TROPICAL AIR MASS AND EXCEPTIONALLY MOIST BOUNDARY LAYER FROM RECENT
RAINS IS EXPECTED TO RESULT IN SOME FOG IN THE MORNING HOURS...ESPECIALLY
IN LOW LYING AREAS.
OUTLOOK...A COLD FRONT WILL PUSH THROUGH THE AREA LATE THURSDAY AND
THURSDAY NIGHT. ASSOCIATED SHOWERS/THUNDERSTORMS ARE EXPECTED TO END
THURSDAY NIGHT. LINGERING LOW LEVEL MOISTURE MAY RESULT IN
RESTRICTIONS IN FOG/STRATUS EARLY FRIDAY. DRY HIGH PRESSURE BUILDING
IN FROM THE NORTH WILL LIMIT RESTRICTIONS THROUGH THE WEEKEND.
CONFIDENCE TABLE...
00-06Z 06-12Z 12-18Z 18-00Z
KCLT HIGH 100% HIGH 87% HIGH 90% HIGH 100%
KGSP HIGH 82% HIGH 87% HIGH 90% HIGH 93%
KAVL HIGH 98% HIGH 92% MED 75% HIGH 100%
KHKY HIGH 100% MED 79% HIGH 91% HIGH 100%
KGMU HIGH 96% HIGH 95% HIGH 90% HIGH 91%
KAND HIGH 100% HIGH 93% HIGH 90% HIGH 93%
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
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JAT
NEAR TERM...LG/WJM
SHORT TERM...CDG
LONG TERM...JAT
AVIATION...WJM
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
929 PM CDT WED AUG 19 2015
.UPDATE...
A STRONG SURFACE COLD FRONT WILL CONTINUE MOVING THROUGH OUR
CENTRAL TEXAS COUNTIES THIS EVENING AND TOWARD THE TEXAS UPPER
COAST THROUGH THURSDAY MORNING. MEANWHILE...A SHORTWAVE TROUGH
ALOFT WILL SHIFT EASTWARD OVER THE AREA TONIGHT WITH THE 850MB
FRONT CURRENTLY TO OUR NORTHWEST MOVING THROUGH BY MORNING.
THE COMBINATION OF WEAK WAA OVER THE TOP OF THE 850MB FRONT...
RICH MOISTURE IN THE 850-700MB COLUMN ON THE 00Z FWD SOUNDING AND
FORCING FROM THE SHORTWAVE WILL RESULT IN MOSTLY LIGHT SHOWERS
ACROSS THE NORTH INTO THE PRE-DAWN HOURS WITH A CHANCE OF SHOWERS
AND THUNDERSTORMS IN VICINITY OF THE SURFACE COLD FRONT ACROSS THE
SOUTHEAST COUNTIES OVERNIGHT AND EARLY THURSDAY MORNING. DRIER AND
COOLER AIR SHOULD CONTINUE TO FILTER IN FROM THE NORTH AND NORTHWEST
WITH PRECIPITATION CHANCES ENDING ACROSS THE IMMEDIATE RED RIVER
VALLEY SHORTLY AFTER MIDNIGHT AS THE SHORTWAVE TROUGH AXIS AND
ELEVATED FRONT ROTATE THROUGH. AREAS NORTH OF I-20 SHOULD CLEAR
OUT FIRST WITH MANY AREAS SEEING COMFORTABLY COOL MORNING LOWS
FROM THE MID 50S TO LOWER 60S...WITH MID 60S TO LOWER 70S FURTHER
SOUTH.
WILL HOLD CHANCE POPS FOR THE ENTIRE AREA OVERNIGHT WITH BEST
CHANCES ACROSS OUR SOUTHEAST COUNTIES WHERE MOISTURE...INSTABILITY
AND FORCING WILL SUSTAIN THE LONGEST. NO SEVERE WEATHER IS
EXPECTED. CLEARING OF CLOUDS AND ASSOCIATED PRECIPITATION SHOULD
CONTINUE INTO THURSDAY...AS THE SHORTWAVE TROUGH CONTINUES
PROGRESSING EAST.
05/
&&
.AVIATION...
/ISSUED 744 PM CDT WED AUG 19 2015/
/00Z TAFS/ A REFRESHINGLY STOUT COLD FRONT (FOR AUGUST ANYWAY)
HAS SURGED SOUTHWARD TO NEAR A JUNCTION-TYLER LINE AS OF 00Z. A
FEW THUNDERSTORMS FORMED ALONG THE BOUNDARY NEAR WACO...BUT HAVE
WEAKENED AS THE BETTER CONVERGENCE MOVED SOUTHWARD WITH THE FRONT.
NO THUNDER EXPECTED NEAR WACO SHOULD END AFTER 01Z.
A FEW SHOWERS ARE STILL EXPECTED TO DEVELOP IN THE VICINITY OF THE
METROPLEX TAF SITES IN THE 03Z-09Z TIMEFRAME...AS WEAK FORCING
FOR ASCENT INCREASES ACROSS NORTH TEXAS LATER TONIGHT. INSTABILITY
IS PRETTY LIMITED...SO WILL OMIT ANY REFERENCE TO THUNDER IN THESE
TAFS OVERNIGHT. SOME MVFR CIGS ARE LIKELY TO DEVELOP AT ALL SITES
ACROSS THE REGION AFTER 08-09Z. WITH WEAK LOW LEVEL COLD AIR
ADVECTION CONTINUING INTO THE MORNING HOURS THURS...EXPECT THESE
CIGS TO PERSIST THROUGH 15-17Z. STRONG AND GUSTY NORTHERLY WINDS
WILL GRADUALLY EASE AFTER 06Z AS PRESSURE GRADIENT RELAXES. WINDS
AT METROPLEX SITES WILL SLOWLY VEER TO A LIGHT EASTERLY DIRECTION
BY 18Z THURS.
BRADSHAW/66
&&
.SYNOPSIS...
THE MAIN STORY WITH THIS FORECAST PACKAGE WILL BE THE COOLER
WEATHER AND RAIN CHANCES OVER THE NEXT 12-24 HOURS. A RETURN TO
WARM CONDITIONS IS EXPECTED LATER THIS WEEK AND THROUGH THE
WEEKEND WITH LOWER CHANCES FOR PRECIPITATION.
&&
.SHORT TERM (TONIGHT THROUGH FRIDAY)...
A VERY DIFFICULT FORECAST EXISTS WITH SOME DIFFERENCES BETWEEN
BOTH HI-RES AND COARSE MODEL SOLUTIONS. AS IS OFTEN THE
CASE...NUMERICAL WEATHER PREDICTION OFTEN STRUGGLES WITH EVENTS
THAT ARE EITHER WEAKLY FORCED OR PRIMARILY DRIVEN BY MESOSCALE
PHENOMENON. IN THE CASE OF TODAY...A BULK OF THE LARGE SCALE
FORCING FOR ASCENT WAS DISPLACED WELL TO THE NORTH OF
NORTH/CENTRAL TEXAS AND THE MAIN FOCUSING MECHANISMS FOR WHAT RAIN
DID FALL THIS MORNING AND THIS AFTERNOON WERE OUTFLOW BOUNDARIES
FROM PREVIOUS CONVECTION ACROSS OK AND THE TX PANHANDLE.
MOST OF THE CONVECTION THIS AFTERNOON ON AREA RADARS APPEAR TO BE
ALONG THE FRONT WHERE SUFFICIENT LOW LEVEL CONVERGENCE IS
OCCURRING. WITH THE FRONT STARTING TO QUICKLY MOVE SOUTHWARD MOST
OF THIS ACTIVITY IS SHORT LIVED AS IT IS BEING UNDERCUT BY THE
SHALLOWER/COOLER AIR.
FOR THE REST OF THE AFTERNOON AND TONIGHT...STILL FEEL CONFIDENT
ENOUGH THAT THERE WILL BE A COUPLE OF AREAS THAT COULD SEE SOME
MEASURABLE PRECIPITATION. THE FIRST WILL BE ALONG OUR SOUTHEAST
ZONES NEAR THE SFC-925 MB FRONT LATER THIS AFTERNOON AND INTO
TONIGHT. MOST COARSE MODELS /EXCLUDING THE NAM/ SUGGEST THAT SOME
LOW LEVEL FRONTOGENESIS WILL OCCUR AND SHOULD YIELD ISOLATED TO
SCATTERED CONVECTION. THE OVERALL SEVERE POTENTIAL SEEMS
RELATIVELY LOW...BUT GIVEN THE UNSTABLE AIRMASS AHEAD OF THE
FRONT...WOULD NOT RULE OUT A STRONG DOWNBURST OR TWO. THERE MAY BE
A SMALL HAIL RISK WITH CONVECTION NEAR THE FRONT...BUT THINK THAT
CONVECTION IS BECOMING UNDERCUT TOO QUICKLY BEFORE HAIL PRODUCTION
CAN OCCUR.
THE SECOND AREA WITH A SLIGHTLY HIGHER CHANCE FOR PRECIPITATION
WILL BE ALONG AND NORTH OF THE INTERSTATE 20 CORRIDOR WHERE 850 MB
FRONTOGENETIC FORCING IS BEING ADVERTISED. PER THE TTU WRF AND
LATEST HRRR SOME AREAS OF ISOLATED TO WIDELY SCATTERED ACTIVITY IS
EXPECTED TO DEVELOP DURING THE OVERNIGHT HOURS INTO EARLY THURSDAY
MORNING. CLOSER TO SUNRISE...THIS ACTIVITY SHOULD SHIFT SOUTHWARD
AS DRIER AIR WORKS ITS WAY IN FROM THE NORTH. CURRENTLY THINK THAT
SOME SKIES ACROSS OUR IMMEDIATE RED RIVER ZONES MAY CLEAR ENOUGH
TO ALLOW FOR SOME DECENT COOLING. WITH THE CONTINUED NORTH
WINDS...THIS SHOULD ALLOW TEMPERATURES TO FALL INTO THE 60S WITH
PERHAPS EVEN A FEW UPPER 50S ALONG THE RED RIVER.
FOR THURSDAY AND THURSDAY NIGHT...THE HIGHEST RAIN CHANCES WILL
REMAIN DOWN ALONG OUR SOUTHEASTERN ZONES WHERE THE FRONT WILL
STALL AND BEGIN TO LOSE ITS BAROCLINICITY. MAX TEMPERATURES WILL
DEPEND ON THE AMOUNT OF SUNSHINE THAT CAN FILTER IN TO HELP OFFSET
SOME OF THE COLD AIR ADVECTION. IN GENERAL THINK THAT HIGHS WILL
CLIMB INTO THE LOW TO MID 80S...EXCEPT ACROSS FAR SOUTHEASTERN
ZONES WHERE UPPER 80S MAY BE POSSIBLE...ESPECIALLY IF THE FRONT
STALLS FURTHER NORTH THAN CURRENT EXPECTATIONS. WITH THE ZONAL
FLOW ALOFT ACROSS THE CENTRAL PLAINS...LOW LEVEL FLOW SHOULD TURN
AROUND TO THE EAST AND EVENTUALLY SOUTHEAST LATE THURSDAY NIGHT
INTO FRIDAY. HELD ON TO SOME LINGERING SLIGHT CHANCE POPS ACROSS
EASTERN ZONES WITH THE MOIST EAST FLOW AS ADVERTISED BY THE ECMWF
AND GFS. INSTABILITY APPEARS MEAGER...BUT WENT AHEAD AND MENTIONED
AN ISOLATED THUNDERSTORM OR TWO IN THE WORDED FORECASTS.
FOR FRIDAY...ANOTHER UPPER WAVE LOOKS TO MOVE EASTWARD OUT FROM
THE INTERMOUNTAIN WEST. THERE IS SOME WEAK LARGE SCALE ASCENT AS
EVIDENCED BY SOME UPPER LEVEL PV ACROSS THE NORTHERN AND
NORTHEASTERN ZONES. AS A RESULT...RETAINED INHERITED SLIGHT CHANCE
POPS ON FRIDAY. WITH THE RETURN TO THE SOUTH FLOW...EXPECT AN
INCREASE IN LOW LEVEL MOISTURE AND AN INCREASE IN THE
TEMPERATURES AS WELL. TEMPERATURES WILL CLIMB BACK TOWARDS
SEASONAL NORMS ON FRIDAY...OUTSIDE ANY PRECIPITATION THAT OCCURS.
&&
.LONG TERM (SATURDAY AND SUNDAY)...
FOR SATURDAY AND SUNDAY...MAINTAINED SLIGHT CHANCES FOR
PRECIPITATION ACROSS NORTHERN AND EASTERN ZONES WITH THESE AREAS
REMAINING ON THE NORTHERN AND EASTERN FRINGES OF A BUILDING MID
LEVEL RIDGE. HIGH TEMPERATURES SHOULD CLIMB INTO THE 90S AREA
WIDE ON SATURDAY. BOTH THE GFS AND ECMWF ADVERTISE A WEAK
BACKDOOR COLD FRONT SOMETIME LATE SUNDAY. THE RIDGE SHOULD
GRADUALLY WEAKEN ON ITS EASTERN PERIPHERY WHICH MAY ALLOW FOR THE
DEVELOPMENT OF SOME PRECIPITATION ALONG THE FRONT. AS A
RESULT...HAVE INTRODUCED LOW CHANCE POPS MAINLY ALONG THE RED
RIVER AND ACROSS EASTERN ZONES FOR SUNDAY AND INTO THE DAY ON
MONDAY. THERE ARE SOME DISCREPANCIES BETWEEN THE GFS AND THE ECMWF
IN THE LONG TERM WITH REGARDS TO HOW FAR SOUTH THIS NEXT COLD
FRONT WILL SWEEP SO CONFIDENCE IS NOT HIGH ENOUGH TO DEVIATE TOO
FAR FROM A CONSENSUS/BLENDED FORECAST.
BAIN
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 67 84 73 93 77 / 40 20 10 20 10
WACO, TX 69 83 74 94 76 / 30 30 20 10 5
PARIS, TX 63 79 64 89 73 / 40 20 20 30 30
DENTON, TX 63 82 69 93 76 / 40 10 10 20 20
MCKINNEY, TX 64 81 69 92 76 / 40 20 10 30 20
DALLAS, TX 68 85 74 94 78 / 40 20 10 20 10
TERRELL, TX 66 81 72 92 76 / 40 30 20 20 10
CORSICANA, TX 68 82 73 93 76 / 30 30 20 20 10
TEMPLE, TX 70 86 73 94 75 / 40 30 20 10 5
MINERAL WELLS, TX 64 83 70 94 75 / 40 20 10 20 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
05/66
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
744 PM CDT WED AUG 19 2015
.AVIATION...
/00Z TAFS/ A REFRESHINGLY STOUT COLD FRONT (FOR AUGUST ANYWAY)
HAS SURGED SOUTHWARD TO NEAR A JUNCTION-TYLER LINE AS OF 00Z. A
FEW THUNDERSTORMS FORMED ALONG THE BOUNDARY NEAR WACO...BUT HAVE
WEAKENED AS THE BETTER CONVERGENCE MOVED SOUTHWARD WITH THE FRONT.
NO THUNDER EXPECTED NEAR WACO SHOULD END AFTER 01Z.
A FEW SHOWERS ARE STILL EXPECTED TO DEVELOP IN THE VICINITY OF THE
METROPLEX TAF SITES IN THE 03Z-09Z TIMEFRAME...AS WEAK FORCING
FOR ASCENT INCREASES ACROSS NORTH TEXAS LATER TONIGHT. INSTABILITY
IS PRETTY LIMITED...SO WILL OMIT ANY REFERENCE TO THUNDER IN THESE
TAFS OVERNIGHT. SOME MVFR CIGS ARE LIKELY TO DEVELOP AT ALL SITES
ACROSS THE REGION AFTER 08-09Z. WITH WEAK LOW LEVEL COLD AIR
ADVECTION CONTINUING INTO THE MORNING HOURS THURS...EXPECT THESE
CIGS TO PERSIST THROUGH 15-17Z. STRONG AND GUSTY NORTHERLY WINDS
WILL GRADUALLY EASE AFTER 06Z AS PRESSURE GRADIENT RELAXES. WINDS
AT METROPLEX SITES WILL SLOWLY VEER TO A LIGHT EASTERLY DIRECTION
BY 18Z THURS.
BRADSHAW
&&
.SYNOPSIS...
THE MAIN STORY WITH THIS FORECAST PACKAGE WILL BE THE COOLER
WEATHER AND RAIN CHANCES OVER THE NEXT 12-24 HOURS. A RETURN TO
WARM CONDITIONS IS EXPECTED LATER THIS WEEK AND THROUGH THE
WEEKEND WITH LOWER CHANCES FOR PRECIPITATION.
&&
.SHORT TERM (TONIGHT THROUGH FRIDAY)...
A VERY DIFFICULT FORECAST EXISTS WITH SOME DIFFERENCES BETWEEN
BOTH HI-RES AND COARSE MODEL SOLUTIONS. AS IS OFTEN THE
CASE...NUMERICAL WEATHER PREDICTION OFTEN STRUGGLES WITH EVENTS
THAT ARE EITHER WEAKLY FORCED OR PRIMARILY DRIVEN BY MESOSCALE
PHENOMENON. IN THE CASE OF TODAY...A BULK OF THE LARGE SCALE
FORCING FOR ASCENT WAS DISPLACED WELL TO THE NORTH OF
NORTH/CENTRAL TEXAS AND THE MAIN FOCUSING MECHANISMS FOR WHAT RAIN
DID FALL THIS MORNING AND THIS AFTERNOON WERE OUTFLOW BOUNDARIES
FROM PREVIOUS CONVECTION ACROSS OK AND THE TX PANHANDLE.
MOST OF THE CONVECTION THIS AFTERNOON ON AREA RADARS APPEAR TO BE
ALONG THE FRONT WHERE SUFFICIENT LOW LEVEL CONVERGENCE IS
OCCURRING. WITH THE FRONT STARTING TO QUICKLY MOVE SOUTHWARD MOST
OF THIS ACTIVITY IS SHORT LIVED AS IT IS BEING UNDERCUT BY THE
SHALLOWER/COOLER AIR.
FOR THE REST OF THE AFTERNOON AND TONIGHT...STILL FEEL CONFIDENT
ENOUGH THAT THERE WILL BE A COUPLE OF AREAS THAT COULD SEE SOME
MEASURABLE PRECIPITATION. THE FIRST WILL BE ALONG OUR SOUTHEAST
ZONES NEAR THE SFC-925 MB FRONT LATER THIS AFTERNOON AND INTO
TONIGHT. MOST COARSE MODELS /EXCLUDING THE NAM/ SUGGEST THAT SOME
LOW LEVEL FRONTOGENESIS WILL OCCUR AND SHOULD YIELD ISOLATED TO
SCATTERED CONVECTION. THE OVERALL SEVERE POTENTIAL SEEMS
RELATIVELY LOW...BUT GIVEN THE UNSTABLE AIRMASS AHEAD OF THE
FRONT...WOULD NOT RULE OUT A STRONG DOWNBURST OR TWO. THERE MAY BE
A SMALL HAIL RISK WITH CONVECTION NEAR THE FRONT...BUT THINK THAT
CONVECTION IS BECOMING UNDERCUT TOO QUICKLY BEFORE HAIL PRODUCTION
CAN OCCUR.
THE SECOND AREA WITH A SLIGHTLY HIGHER CHANCE FOR PRECIPITATION
WILL BE ALONG AND NORTH OF THE INTERSTATE 20 CORRIDOR WHERE 850 MB
FRONTOGENETIC FORCING IS BEING ADVERTISED. PER THE TTU WRF AND
LATEST HRRR SOME AREAS OF ISOLATED TO WIDELY SCATTERED ACTIVITY IS
EXPECTED TO DEVELOP DURING THE OVERNIGHT HOURS INTO EARLY THURSDAY
MORNING. CLOSER TO SUNRISE...THIS ACTIVITY SHOULD SHIFT SOUTHWARD
AS DRIER AIR WORKS ITS WAY IN FROM THE NORTH. CURRENTLY THINK THAT
SOME SKIES ACROSS OUR IMMEDIATE RED RIVER ZONES MAY CLEAR ENOUGH
TO ALLOW FOR SOME DECENT COOLING. WITH THE CONTINUED NORTH
WINDS...THIS SHOULD ALLOW TEMPERATURES TO FALL INTO THE 60S WITH
PERHAPS EVEN A FEW UPPER 50S ALONG THE RED RIVER.
FOR THURSDAY AND THURSDAY NIGHT...THE HIGHEST RAIN CHANCES WILL
REMAIN DOWN ALONG OUR SOUTHEASTERN ZONES WHERE THE FRONT WILL
STALL AND BEGIN TO LOSE ITS BAROCLINICITY. MAX TEMPERATURES WILL
DEPEND ON THE AMOUNT OF SUNSHINE THAT CAN FILTER IN TO HELP OFFSET
SOME OF THE COLD AIR ADVECTION. IN GENERAL THINK THAT HIGHS WILL
CLIMB INTO THE LOW TO MID 80S...EXCEPT ACROSS FAR SOUTHEASTERN
ZONES WHERE UPPER 80S MAY BE POSSIBLE...ESPECIALLY IF THE FRONT
STALLS FURTHER NORTH THAN CURRENT EXPECTATIONS. WITH THE ZONAL
FLOW ALOFT ACROSS THE CENTRAL PLAINS...LOW LEVEL FLOW SHOULD TURN
AROUND TO THE EAST AND EVENTUALLY SOUTHEAST LATE THURSDAY NIGHT
INTO FRIDAY. HELD ON TO SOME LINGERING SLIGHT CHANCE POPS ACROSS
EASTERN ZONES WITH THE MOIST EAST FLOW AS ADVERTISED BY THE ECMWF
AND GFS. INSTABILITY APPEARS MEAGER...BUT WENT AHEAD AND MENTIONED
AN ISOLATED THUNDERSTORM OR TWO IN THE WORDED FORECASTS.
FOR FRIDAY...ANOTHER UPPER WAVE LOOKS TO MOVE EASTWARD OUT FROM
THE INTERMOUNTAIN WEST. THERE IS SOME WEAK LARGE SCALE ASCENT AS
EVIDENCED BY SOME UPPER LEVEL PV ACROSS THE NORTHERN AND
NORTHEASTERN ZONES. AS A RESULT...RETAINED INHERITED SLIGHT CHANCE
POPS ON FRIDAY. WITH THE RETURN TO THE SOUTH FLOW...EXPECT AN
INCREASE IN LOW LEVEL MOISTURE AND AN INCREASE IN THE
TEMPERATURES AS WELL. TEMPERATURES WILL CLIMB BACK TOWARDS
SEASONAL NORMS ON FRIDAY...OUTSIDE ANY PRECIPITATION THAT OCCURS.
&&
.LONG TERM (SATURDAY AND SUNDAY)...
FOR SATURDAY AND SUNDAY...MAINTAINED SLIGHT CHANCES FOR
PRECIPITATION ACROSS NORTHERN AND EASTERN ZONES WITH THESE AREAS
REMAINING ON THE NORTHERN AND EASTERN FRINGES OF A BUILDING MID
LEVEL RIDGE. HIGH TEMPERATURES SHOULD CLIMB INTO THE 90S AREA
WIDE ON SATURDAY. BOTH THE GFS AND ECMWF ADVERTISE A WEAK
BACKDOOR COLD FRONT SOMETIME LATE SUNDAY. THE RIDGE SHOULD
GRADUALLY WEAKEN ON ITS EASTERN PERIPHERY WHICH MAY ALLOW FOR THE
DEVELOPMENT OF SOME PRECIPITATION ALONG THE FRONT. AS A
RESULT...HAVE INTRODUCED LOW CHANCE POPS MAINLY ALONG THE RED
RIVER AND ACROSS EASTERN ZONES FOR SUNDAY AND INTO THE DAY ON
MONDAY. THERE ARE SOME DISCREPANCIES BETWEEN THE GFS AND THE ECMWF
IN THE LONG TERM WITH REGARDS TO HOW FAR SOUTH THIS NEXT COLD
FRONT WILL SWEEP SO CONFIDENCE IS NOT HIGH ENOUGH TO DEVIATE TOO
FAR FROM A CONSENSUS/BLENDED FORECAST.
BAIN
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 67 84 73 93 77 / 40 20 10 20 10
WACO, TX 69 83 74 94 76 / 30 30 20 10 5
PARIS, TX 63 79 64 89 73 / 40 20 20 30 30
DENTON, TX 63 82 69 93 76 / 40 10 10 20 20
MCKINNEY, TX 64 81 69 92 76 / 40 20 10 30 20
DALLAS, TX 68 85 74 94 78 / 40 20 10 20 10
TERRELL, TX 66 81 72 92 76 / 40 30 20 20 10
CORSICANA, TX 68 82 73 93 76 / 30 30 20 20 10
TEMPLE, TX 70 86 73 94 75 / 40 30 20 10 5
MINERAL WELLS, TX 64 83 70 94 75 / 40 20 10 20 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1235 PM CDT TUE AUG 18 2015
.AVIATION...
INITIAL COLD FRONT ALREADY INTO THE NWRN TX PANHANDLE WITH A
STRONGER NORTHERLY PUSH BACK OVER NERN COLO...NWRN KS...AND SWRN
NEBR. THIS FRONT IS EXPECTED TO BE THE FOCUS FOR TS DEVELOPMENT
LATER THIS AFTN ACROSS THE PANHANDLES THEN SHIFTING EWD INTO WRN
OKLA. KCDS WILL SEE THE BEST CHANCE FOR SOME OF THIS ACTIVITY WITH
KPVW SECOND AND KLBB A DISTANT THIRD. PEAK CHANCE COMES BTWN 00Z
AND 06Z. WILL THUS LEAVE TEMPO OUT ATTM AND LET NEXT SHIFT
REEVALUATE WITH THE 00Z TAF SET. ONLY OTHER ISSUES ARE GOOD
POTENTIAL FOR NORTH TO NE WINDS TO BECOME A BIT GUSTY BEHIND THE
FRONT NEAR SUNRISE WEDNESDAY AND A VERY SMALL CHANCE OF MVFR CIGS
DEVELOPING BEHIND THE FRONT WEDNESDAY MORNING.
&&
.PREV DISCUSSION... /ISSUED 653 AM CDT TUE AUG 18 2015/
UPDATE...
SHOWER AND T-STORM ACTIVITY ALONG THE TX-NM STATE LINE HAS
GRADUALLY CONGEALED INTO A BROAD BLOB OF MAINLY LIGHT RAIN...BUT
WITH A FEW EMBEDDED T-STORMS...MAINLY OVER COCHRAN AND YOAKUM
COUNTIES. WE HAVE UPPED POPS CONSIDERABLY IN THIS AREA FOR THE
MORNING HOURS. ELSEWHERE...SOME ADDITIONAL DEVELOPMENT IS NOTED
ACROSS FLOYD AND BRISCOE COUNTIES...BUT WE HAVE KEPT THE ISOLATED
MENTION IN PLACE FOR NOW.
AVIATION...
SCATTERED -SHRA AND MORE ISOLATED -TSRA COULD AFFECT ANY OF THE
TERMINALS THROUGH 15 OR 16 UTC. WE HAVE GONE AHEAD AND ADDED TEMPO
GROUPS AT KLBB AND KPVW TO COVER THIS POTENTIAL. TSRA WILL THEN RETURN
TO THE FORECAST THIS EVENING AS A COLD FRONT MOVES IN FROM THE
NORTH. AT THIS TIME...CONFIDENCE IS TOO LOW IN THE TIMING AND
COVERAGE OF TSRA TO INCLUDE IN THE FORECASTS. ALSO...THE EXACT
TIME OF THE FROPA THROUGH THE TERMINALS REMAINS UNCERTAIN DUE TO
POSSIBLE INTERACTION WITH T-STORM OUTFLOWS.
PREV DISCUSSION... /ISSUED 402 AM CDT TUE AUG 18 2015/
SHORT TERM...
WATER VAPOR IMAGERY SHOWS A SHARP SHORTWAVE TROUGH CROSSING THE
ROCKIES AND EMERGING OVER THE CENTRAL AND NRN PLAINS THIS MORNING.
THIS IS PRODUCING SCATTERED CONVECTIVE ACTIVITY FROM
NEBRASKA...ARCING EAST INTO CENTRAL KS...THEN BACK SW ACROSS NW OKLA
AND ERN TX PANHANDLE...AND INTO ERN AND SRN NEW MEXICO. THIS
ACTIVITY IS MOSTLY SPLITTING OUR FORECAST AREA AT 3 AM...WITH THE
EASTERN BATCH JUST NICKING OUR NE COUNTIES AND THE WESTERN BATCH
STAYING WEST OF THE STATE LINE. HOWEVER...RADAR IS SHOWING A SLIGHT
UPTICK IN COVERAGE AND INTENSITY AT THIS TIME...AND THE HRRR AND RAP
SUGGEST THAT ISOLATED TO SCATTERED COVERAGE OF SHOWERS AND STORMS
WILL WORK THEIR WAY SEWD ACROSS MOST OF OUR FORECAST AREA THIS
MORNING. THE ACTIVITY WILL TEND TO WANE TOWARD SUNRISE...AND AT
THIS TIME IT LOOKS LIKE AN ISOLATED MENTION IN THE FORECAST AFTER
12 UTC WILL BE SUFFICIENT.
IT NOW APPEARS THAT MOST OF THE DAY WILL BE PRETTY QUIET AS MODEST
SUBSIDENCE REPLACES THE MODEST LIFT MOVING THROUGH THIS MORNING.
THIS SHOULD ALLOW TEMPS TO WARM A FEW DEGREES FROM YESTERDAY/S
READINGS WITH HIGHS EXPECTED TO TOP OUT IN THE LOWER 90S NORTHWEST
TO NEAR 100 IN THE SOUTHEAST. MEANWHILE...THE MUCH ANTICIPATED COLD
FRONT....CURRENTLY MOVING THROUGH ERN COLO AND WRN KS...WILL BE
MAKING IT/S WAY SOUTH THROUGH THE PANHANDLES. THE LATEST HIGH-RES
GUIDANCE IS IN GOOD AGREEMENT THAT AN INITIAL WIND SHIFT WILL WORK
INTO THE FAR SW TX PANHANDLE AND NW SPLNS BY EARLY AFTERNOON...BUT
THEN NOT MAKE MUCH ADDITIONAL PROGRESS THROUGH EARLY EVENING. THIS
WILL SET UP A SURFACE TROUGH RUNNING FROM THE WRN SOUTH PLAINS
INTO THE SRN TX PANHANDLE. DESPITE A NICE BUILDUP OF CAPE TO NEAR
3000 J/KG IN THIS AREA...THE CAP IS EXPECTED TO HOLD THROUGH MOST
OF THE AFTERNOON. LARGE-SCALE ASCENT SHOULD BEGIN TO INCREASE
EARLY THIS EVENING AS THE NEXT VORT MAX SWINGS ACROSS THE SRN
ROCKIES. ALTHOUGH THE BULK OF THIS LIFT WILL BE OFF TO OUR
NORTH...IT SHOULD TRIGGER SOME T-STORM DEVELOPMENT AS IT SPREADS
OVER THE FRONT AND SURFACE TROUGH. UNFORTUNATELY...MODEL GUIDANCE
REMAINS HIGHLY VARIABLE AND INCONSISTENT IN THE PLACEMENT AND
COVERAGE OF QPF AND MODEL REFLECTIVITY FIELDS...INCLUDING A FEW
SOLUTIONS...SUCH AS THE 00 UTC TTU-WRF...WHICH KEEPS THE FORECAST
AREA MOSTLY PRECIP FREE. AS SUCH...OUR CONFIDENCE REMAINS LOW
REGARDS THE EXTENT OF THUNDERSTORMS THIS EVENING AND THUS POPS ARE
ONLY IN THE 20 TO 40 PERCENT RANGE....MAXIMIZED ACROSS THE FAR SE
TX PANHANDLE. THE AVAILABLE INSTABILITY AND DEEP-LAYER SHEAR
SUPPORT THE IDEA OF SOME STORM ORGANIZATION AND A SEVERE WEATHER
THREAT...FOCUSED ON THE FAR SRN TX PANHANDLE AND NW
SPLNS...ALTHOUGH THE COVERAGE MAY BE JUST TOO LIMITED TO BE OF
SIGNIFICANT IMPACT.
THE COLD FRONT WILL SURGE THROUGH THE FORECAST AREA OVERNIGHT...WITH
BREEZY NE WINDS EXPECTED WITH THE FROPA EVEN OUTSIDE OF ANY T-STORM
ACTIVITY. LOW STRATUS WILL ALSO EXPAND IN COVERAGE BEHIND THE FRONT.
THE BEST RAIN CHANCES WILL GRADUALLY SHIFT EWD INTO THE ROLLING
PLAINS EARLY WEDNESDAY MORNING.
LONG TERM...
MUCH COOLER AIR WILL BE ADVECTING INTO THE SOUTH PLAINS ON GUSTY
NORTHEASTERLY WINDS WEDNESDAY BEHIND THE EARLY DAY FROPA. SUSTAINED
WINDS NEAR 20 KNOTS COUPLED WITH HIGHS ONLY CLIMBING INTO THE 70S
FOR MOST SPOTS WILL MAKE FOR A FALL-LIKE FEEL IN THE AIR. IN
ADDITION...MOIST UPGLIDE ABOVE THE FRONTAL ZONE WILL YIELD A STRATUS
DECK WITH ENOUGH ELEVATED INSTABILITY PERHAPS SUPPORTING A RISK OF A
FEW SHOWERS/STORMS ACROSS THE EASTERN AND SOUTHEASTERN ZONES. OF
NOTE...THE RECORD MINIMUM HIGH FOR AUGUST 19TH IN LUBBOCK IS 74
DEGREES /SET IN 1956/ AND THIS COULD BE THREATENED IF CLOUDS HANG
TOUGH ALL DAY. SURFACE RIDGING WILL THEN SETTLE OVER THE REGION WITH
LIGHT WINDS AND THE COOLEST AIR SINCE LATE MAY. DEPENDING ON WHETHER
SKIES COMPLETELY CLEAR AND EXACTLY HOW LOW DEWPOINTS CAN DROP WITHIN
THE RIDGE...WE COULD ALSO THREATEN THE RECORD LOW THURSDAY MORNING
/THE CURRENT RECORD IS 54 DEGREES SET IN 1915/.
THE SURFACE RIDGE WILL SLIDE EASTWARD ON THURSDAY ALLOWING SOUTHERLY
WINDS TO GRADUALLY RETURN AND COUPLED WITH INCREASED INSOLATION
HIGHS WILL REBOUND BACK INTO THE 80S. WE WILL THEN SEE SLIM STORM
CHANCES CREEP BACK INTO THE FORECAST THURSDAY NIGHT INTO FRIDAY AS
ONE OR MORE SUBTLE DISTURBANCES MOVE THROUGH THE QUASI-ZONAL FLOW
AND GRAZE THE AREA FROM THE NORTH. THE SUPPRESSED SOUTHWESTERN UPPER
RIDGE IS THEN FORECAST TO EXPAND NORTHWARD AND BRIDGE TO AN UPPER
HIGH CENTERED OVER FLORID THIS WEEKEND WHILE AT THE SAME TIME A
SHARP TROUGH MOVES STEADILY ACROSS THE NORTHERN TIER OF THE
NATION. THE BUILDING HEIGHTS AND PROLONGED SOUTHERLY FLOW WILL
ALLOW TEMPERATURES TO MODERATE BACK UP TO NEAR AVERAGE BY FRIDAY
AND SATURDAY. EVEN WITH THE RIDGE BUILDING MORE SQUARELY
OVERHEAD...A SUBTROPICAL MOISTURE FETCH ALONG WITH CONVERGENCE
ALONG A SURFACE TROUGH WILL KEEP LOW THUNDER CHANCES GOING ACROSS
THE WESTERN ZONES ON SATURDAY. THE NORTHERN STREAM SYSTEM WILL
THEN SEND A COLD FRONT SOUTHWARD INTO THE SOUTHERN PLAINS ON
SUNDAY BEFORE STALLING OUT SOMEWHERE NEARBY AND THEN WASHING OUT
EARLY NEXT WEEK. THIS FRONT WILL PROVIDE AT LEAST A SLIM SHOT OF
ADDITIONAL CONVECTION ON SUNDAY...THOUGH WITHOUT ANY UPPER SUPPORT
COVERAGE WOULD LIKELY BE NO BETTER THAN SCATTERED.
AFTER ANOTHER BRIEF AND LESS DRAMATIC COOL DOWN /THAN ON
WEDNESDAY/ WITH THE FRONT LATE THIS WEEKEND...HOTTER AND DRY
WEATHER SHOULD FOLLOW. THIS WILL OCCUR AS UPPER RIDGING IS
PROGGED TO AMPLIFY OVER THE SOUTHERN ROCKIES INTO THE SOUTHERN
HIGH PLAINS DURING THE EARLY AND MIDDLE PARTS OF NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 92 58 75 53 / 20 30 10 0
TULIA 91 60 74 54 / 10 40 20 0
PLAINVIEW 92 61 74 53 / 10 30 20 0
LEVELLAND 93 63 77 56 / 10 30 20 0
LUBBOCK 94 65 77 57 / 10 30 20 10
DENVER CITY 96 65 79 56 / 10 20 20 10
BROWNFIELD 94 65 79 56 / 10 30 20 10
CHILDRESS 96 67 78 58 / 20 40 30 10
SPUR 95 67 78 58 / 10 30 30 20
ASPERMONT 99 70 83 61 / 10 30 30 30
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
07
AREA FORECAST DISCUSSION...UPDATED
NWS LUBBOCK TX
653 AM CDT TUE AUG 18 2015
.UPDATE...
SHOWER AND T-STORM ACTIVITY ALONG THE TX-NM STATE LINE HAS
GRADUALLY CONGEALED INTO A BROAD BLOB OF MAINLY LIGHT RAIN...BUT
WITH A FEW EMBEDDED T-STORMS...MAINLY OVER COCHRAN AND YOAKUM
COUNTIES. WE HAVE UPPED POPS CONSIDERABLY IN THIS AREA FOR THE
MORNING HOURS. ELSEWHERE...SOME ADDITIONAL DEVELOPMENT IS NOTED
ACROSS FLOYD AND BRISCOE COUNTIES...BUT WE HAVE KEPT THE ISOLATED
MENTION IN PLACE FOR NOW.
&&
.AVIATION...
SCATTERED -SHRA AND MORE ISOLATED -TSRA COULD AFFECT ANY OF THE
TERMINALS THROUGH 15 OR 16 UTC. WE HAVE GONE AHEAD AND ADDED TEMPO
GROUPS AT KLBB AND KPVW TO COVER THIS POTENTIAL. TSRA WILL THEN RETURN
TO THE FORECAST THIS EVENING AS A COLD FRONT MOVES IN FROM THE
NORTH. AT THIS TIME...CONFIDENCE IS TOO LOW IN THE TIMING AND
COVERAGE OF TSRA TO INCLUDE IN THE FORECASTS. ALSO...THE EXACT
TIME OF THE FROPA THROUGH THE TERMINALS REMAINS UNCERTAIN DUE TO
POSSIBLE INTERACTION WITH T-STORM OUTFLOWS.
&&
.PREV DISCUSSION... /ISSUED 402 AM CDT TUE AUG 18 2015/
SHORT TERM...
WATER VAPOR IMAGERY SHOWS A SHARP SHORTWAVE TROUGH CROSSING THE
ROCKIES AND EMERGING OVER THE CENTRAL AND NRN PLAINS THIS MORNING.
THIS IS PRODUCING SCATTERED CONVECTIVE ACTIVITY FROM
NEBRASKA...ARCING EAST INTO CENTRAL KS...THEN BACK SW ACROSS NW OKLA
AND ERN TX PANHANDLE...AND INTO ERN AND SRN NEW MEXICO. THIS
ACTIVITY IS MOSTLY SPLITTING OUR FORECAST AREA AT 3 AM...WITH THE
EASTERN BATCH JUST NICKING OUR NE COUNTIES AND THE WESTERN BATCH
STAYING WEST OF THE STATE LINE. HOWEVER...RADAR IS SHOWING A SLIGHT
UPTICK IN COVERAGE AND INTENSITY AT THIS TIME...AND THE HRRR AND RAP
SUGGEST THAT ISOLATED TO SCATTERED COVERAGE OF SHOWERS AND STORMS
WILL WORK THEIR WAY SEWD ACROSS MOST OF OUR FORECAST AREA THIS
MORNING. THE ACTIVITY WILL TEND TO WANE TOWARD SUNRISE...AND AT
THIS TIME IT LOOKS LIKE AN ISOLATED MENTION IN THE FORECAST AFTER
12 UTC WILL BE SUFFICIENT.
IT NOW APPEARS THAT MOST OF THE DAY WILL BE PRETTY QUIET AS MODEST
SUBSIDENCE REPLACES THE MODEST LIFT MOVING THROUGH THIS MORNING.
THIS SHOULD ALLOW TEMPS TO WARM A FEW DEGREES FROM YESTERDAY/S
READINGS WITH HIGHS EXPECTED TO TOP OUT IN THE LOWER 90S NORTHWEST
TO NEAR 100 IN THE SOUTHEAST. MEANWHILE...THE MUCH ANTICIPATED COLD
FRONT....CURRENTLY MOVING THROUGH ERN COLO AND WRN KS...WILL BE
MAKING IT/S WAY SOUTH THROUGH THE PANHANDLES. THE LATEST HIGH-RES
GUIDANCE IS IN GOOD AGREEMENT THAT AN INITIAL WIND SHIFT WILL WORK
INTO THE FAR SW TX PANHANDLE AND NW SPLNS BY EARLY AFTERNOON...BUT
THEN NOT MAKE MUCH ADDITIONAL PROGRESS THROUGH EARLY EVENING. THIS
WILL SET UP A SURFACE TROUGH RUNNING FROM THE WRN SOUTH PLAINS
INTO THE SRN TX PANHANDLE. DESPITE A NICE BUILDUP OF CAPE TO NEAR
3000 J/KG IN THIS AREA...THE CAP IS EXPECTED TO HOLD THROUGH MOST
OF THE AFTERNOON. LARGE-SCALE ASCENT SHOULD BEGIN TO INCREASE
EARLY THIS EVENING AS THE NEXT VORT MAX SWINGS ACROSS THE SRN
ROCKIES. ALTHOUGH THE BULK OF THIS LIFT WILL BE OFF TO OUR
NORTH...IT SHOULD TRIGGER SOME T-STORM DEVELOPMENT AS IT SPREADS
OVER THE FRONT AND SURFACE TROUGH. UNFORTUNATELY...MODEL GUIDANCE
REMAINS HIGHLY VARIABLE AND INCONSISTENT IN THE PLACEMENT AND
COVERAGE OF QPF AND MODEL REFLECTIVITY FIELDS...INCLUDING A FEW
SOLUTIONS...SUCH AS THE 00 UTC TTU-WRF...WHICH KEEPS THE FORECAST
AREA MOSTLY PRECIP FREE. AS SUCH...OUR CONFIDENCE REMAINS LOW
REGARDS THE EXTENT OF THUNDERSTORMS THIS EVENING AND THUS POPS ARE
ONLY IN THE 20 TO 40 PERCENT RANGE....MAXIMIZED ACROSS THE FAR SE
TX PANHANDLE. THE AVAILABLE INSTABILITY AND DEEP-LAYER SHEAR
SUPPORT THE IDEA OF SOME STORM ORGANIZATION AND A SEVERE WEATHER
THREAT...FOCUSED ON THE FAR SRN TX PANHANDLE AND NW
SPLNS...ALTHOUGH THE COVERAGE MAY BE JUST TOO LIMITED TO BE OF
SIGNIFICANT IMPACT.
THE COLD FRONT WILL SURGE THROUGH THE FORECAST AREA OVERNIGHT...WITH
BREEZY NE WINDS EXPECTED WITH THE FROPA EVEN OUTSIDE OF ANY T-STORM
ACTIVITY. LOW STRATUS WILL ALSO EXPAND IN COVERAGE BEHIND THE FRONT.
THE BEST RAIN CHANCES WILL GRADUALLY SHIFT EWD INTO THE ROLLING
PLAINS EARLY WEDNESDAY MORNING.
LONG TERM...
MUCH COOLER AIR WILL BE ADVECTING INTO THE SOUTH PLAINS ON GUSTY
NORTHEASTERLY WINDS WEDNESDAY BEHIND THE EARLY DAY FROPA. SUSTAINED
WINDS NEAR 20 KNOTS COUPLED WITH HIGHS ONLY CLIMBING INTO THE 70S
FOR MOST SPOTS WILL MAKE FOR A FALL-LIKE FEEL IN THE AIR. IN
ADDITION...MOIST UPGLIDE ABOVE THE FRONTAL ZONE WILL YIELD A STRATUS
DECK WITH ENOUGH ELEVATED INSTABILITY PERHAPS SUPPORTING A RISK OF A
FEW SHOWERS/STORMS ACROSS THE EASTERN AND SOUTHEASTERN ZONES. OF
NOTE...THE RECORD MINIMUM HIGH FOR AUGUST 19TH IN LUBBOCK IS 74
DEGREES /SET IN 1956/ AND THIS COULD BE THREATENED IF CLOUDS HANG
TOUGH ALL DAY. SURFACE RIDGING WILL THEN SETTLE OVER THE REGION WITH
LIGHT WINDS AND THE COOLEST AIR SINCE LATE MAY. DEPENDING ON WHETHER
SKIES COMPLETELY CLEAR AND EXACTLY HOW LOW DEWPOINTS CAN DROP WITHIN
THE RIDGE...WE COULD ALSO THREATEN THE RECORD LOW THURSDAY MORNING
/THE CURRENT RECORD IS 54 DEGREES SET IN 1915/.
THE SURFACE RIDGE WILL SLIDE EASTWARD ON THURSDAY ALLOWING SOUTHERLY
WINDS TO GRADUALLY RETURN AND COUPLED WITH INCREASED INSOLATION
HIGHS WILL REBOUND BACK INTO THE 80S. WE WILL THEN SEE SLIM STORM
CHANCES CREEP BACK INTO THE FORECAST THURSDAY NIGHT INTO FRIDAY AS
ONE OR MORE SUBTLE DISTURBANCES MOVE THROUGH THE QUASI-ZONAL FLOW
AND GRAZE THE AREA FROM THE NORTH. THE SUPPRESSED SOUTHWESTERN UPPER
RIDGE IS THEN FORECAST TO EXPAND NORTHWARD AND BRIDGE TO AN UPPER
HIGH CENTERED OVER FLORID THIS WEEKEND WHILE AT THE SAME TIME A
SHARP TROUGH MOVES STEADILY ACROSS THE NORTHERN TIER OF THE
NATION. THE BUILDING HEIGHTS AND PROLONGED SOUTHERLY FLOW WILL
ALLOW TEMPERATURES TO MODERATE BACK UP TO NEAR AVERAGE BY FRIDAY
AND SATURDAY. EVEN WITH THE RIDGE BUILDING MORE SQUARELY
OVERHEAD...A SUBTROPICAL MOISTURE FETCH ALONG WITH CONVERGENCE
ALONG A SURFACE TROUGH WILL KEEP LOW THUNDER CHANCES GOING ACROSS
THE WESTERN ZONES ON SATURDAY. THE NORTHERN STREAM SYSTEM WILL
THEN SEND A COLD FRONT SOUTHWARD INTO THE SOUTHERN PLAINS ON
SUNDAY BEFORE STALLING OUT SOMEWHERE NEARBY AND THEN WASHING OUT
EARLY NEXT WEEK. THIS FRONT WILL PROVIDE AT LEAST A SLIM SHOT OF
ADDITIONAL CONVECTION ON SUNDAY...THOUGH WITHOUT ANY UPPER SUPPORT
COVERAGE WOULD LIKELY BE NO BETTER THAN SCATTERED.
AFTER ANOTHER BRIEF AND LESS DRAMATIC COOL DOWN /THAN ON
WEDNESDAY/ WITH THE FRONT LATE THIS WEEKEND...HOTTER AND DRY
WEATHER SHOULD FOLLOW. THIS WILL OCCUR AS UPPER RIDGING IS
PROGGED TO AMPLIFY OVER THE SOUTHERN ROCKIES INTO THE SOUTHERN
HIGH PLAINS DURING THE EARLY AND MIDDLE PARTS OF NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 92 58 75 53 / 20 30 10 0
TULIA 91 60 74 54 / 20 40 20 0
PLAINVIEW 92 61 74 53 / 20 30 20 0
LEVELLAND 93 63 77 56 / 20 30 20 0
LUBBOCK 94 65 77 57 / 20 30 20 10
DENVER CITY 96 65 79 56 / 50 20 20 10
BROWNFIELD 94 65 79 56 / 20 30 20 10
CHILDRESS 96 67 78 58 / 20 40 30 10
SPUR 95 67 78 58 / 20 30 30 20
ASPERMONT 99 70 83 61 / 20 30 30 30
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
33/23/
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
402 AM CDT TUE AUG 18 2015
.SHORT TERM...
WATER VAPOR IMAGERY SHOWS A SHARP SHORTWAVE TROUGH CROSSING THE
ROCKIES AND EMERGING OVER THE CENTRAL AND NRN PLAINS THIS MORNING.
THIS IS PRODUCING SCATTERED CONVECTIVE ACTIVITY FROM
NEBRASKA...ARCING EAST INTO CENTRAL KS...THEN BACK SW ACROSS NW OKLA
AND ERN TX PANHANDLE...AND INTO ERN AND SRN NEW MEXICO. THIS
ACTIVITY IS MOSTLY SPLITTING OUR FORECAST AREA AT 3 AM...WITH THE
EASTERN BATCH JUST NICKING OUR NE COUNTIES AND THE WESTERN BATCH
STAYING WEST OF THE STATE LINE. HOWEVER...RADAR IS SHOWING A SLIGHT
UPTICK IN COVERAGE AND INTENSITY AT THIS TIME...AND THE HRRR AND RAP
SUGGEST THAT ISOLATED TO SCATTERED COVERAGE OF SHOWERS AND STORMS
WILL WORK THEIR WAY SEWD ACROSS MOST OF OUR FORECAST AREA THIS
MORNING. THE ACTIVITY WILL TEND TO WANE TOWARD SUNRISE...AND AT
THIS TIME IT LOOKS LIKE AN ISOLATED MENTION IN THE FORECAST AFTER
12 UTC WILL BE SUFFICIENT.
IT NOW APPEARS THAT MOST OF THE DAY WILL BE PRETTY QUIET AS MODEST
SUBSIDENCE REPLACES THE MODEST LIFT MOVING THROUGH THIS MORNING.
THIS SHOULD ALLOW TEMPS TO WARM A FEW DEGREES FROM YESTERDAY/S
READINGS WITH HIGHS EXPECTED TO TOP OUT IN THE LOWER 90S NORTHWEST
TO NEAR 100 IN THE SOUTHEAST. MEANWHILE...THE MUCH ANTICIPATED COLD
FRONT....CURRENTLY MOVING THROUGH ERN COLO AND WRN KS...WILL BE
MAKING IT/S WAY SOUTH THROUGH THE PANHANDLES. THE LATEST HIGH-RES
GUIDANCE IS IN GOOD AGREEMENT THAT AN INITIAL WIND SHIFT WILL WORK
INTO THE FAR SW TX PANHANDLE AND NW SPLNS BY EARLY AFTERNOON...BUT
THEN NOT MAKE MUCH ADDITIONAL PROGRESS THROUGH EARLY EVENING. THIS
WILL SET UP A SURFACE TROUGH RUNNING FROM THE WRN SOUTH PLAINS
INTO THE SRN TX PANHANDLE. DESPITE A NICE BUILDUP OF CAPE TO NEAR
3000 J/KG IN THIS AREA...THE CAP IS EXPECTED TO HOLD THROUGH MOST
OF THE AFTERNOON. LARGE-SCALE ASCENT SHOULD BEGIN TO INCREASE
EARLY THIS EVENING AS THE NEXT VORT MAX SWINGS ACROSS THE SRN
ROCKIES. ALTHOUGH THE BULK OF THIS LIFT WILL BE OFF TO OUR
NORTH...IT SHOULD TRIGGER SOME T-STORM DEVELOPMENT AS IT SPREADS
OVER THE FRONT AND SURFACE TROUGH. UNFORTUNATELY...MODEL GUIDANCE
REMAINS HIGHLY VARIABLE AND INCONSISTENT IN THE PLACEMENT AND
COVERAGE OF QPF AND MODEL REFLECTIVITY FIELDS...INCLUDING A FEW
SOLUTIONS...SUCH AS THE 00 UTC TTU-WRF...WHICH KEEPS THE FORECAST
AREA MOSTLY PRECIP FREE. AS SUCH...OUR CONFIDENCE REMAINS LOW
REGARDS THE EXTENT OF THUNDERSTORMS THIS EVENING AND THUS POPS ARE
ONLY IN THE 20 TO 40 PERCENT RANGE....MAXIMIZED ACROSS THE FAR SE
TX PANHANDLE. THE AVAILABLE INSTABILITY AND DEEP-LAYER SHEAR
SUPPORT THE IDEA OF SOME STORM ORGANIZATION AND A SEVERE WEATHER
THREAT...FOCUSED ON THE FAR SRN TX PANHANDLE AND NW
SPLNS...ALTHOUGH THE COVERAGE MAY BE JUST TOO LIMITED TO BE OF
SIGNIFICANT IMPACT.
THE COLD FRONT WILL SURGE THROUGH THE FORECAST AREA OVERNIGHT...WITH
BREEZY NE WINDS EXPECTED WITH THE FROPA EVEN OUTSIDE OF ANY T-STORM
ACTIVITY. LOW STRATUS WILL ALSO EXPAND IN COVERAGE BEHIND THE FRONT.
THE BEST RAIN CHANCES WILL GRADUALLY SHIFT EWD INTO THE ROLLING
PLAINS EARLY WEDNESDAY MORNING.
.LONG TERM...
MUCH COOLER AIR WILL BE ADVECTING INTO THE SOUTH PLAINS ON GUSTY
NORTHEASTERLY WINDS WEDNESDAY BEHIND THE EARLY DAY FROPA. SUSTAINED
WINDS NEAR 20 KNOTS COUPLED WITH HIGHS ONLY CLIMBING INTO THE 70S
FOR MOST SPOTS WILL MAKE FOR A FALL-LIKE FEEL IN THE AIR. IN
ADDITION...MOIST UPGLIDE ABOVE THE FRONTAL ZONE WILL YIELD A STRATUS
DECK WITH ENOUGH ELEVATED INSTABILITY PERHAPS SUPPORTING A RISK OF A
FEW SHOWERS/STORMS ACROSS THE EASTERN AND SOUTHEASTERN ZONES. OF
NOTE...THE RECORD MINIMUM HIGH FOR AUGUST 19TH IN LUBBOCK IS 74
DEGREES /SET IN 1956/ AND THIS COULD BE THREATENED IF CLOUDS HANG
TOUGH ALL DAY. SURFACE RIDGING WILL THEN SETTLE OVER THE REGION WITH
LIGHT WINDS AND THE COOLEST AIR SINCE LATE MAY. DEPENDING ON WHETHER
SKIES COMPLETELY CLEAR AND EXACTLY HOW LOW DEWPOINTS CAN DROP WITHIN
THE RIDGE...WE COULD ALSO THREATEN THE RECORD LOW THURSDAY MORNING
/THE CURRENT RECORD IS 54 DEGREES SET IN 1915/.
THE SURFACE RIDGE WILL SLIDE EASTWARD ON THURSDAY ALLOWING SOUTHERLY
WINDS TO GRADUALLY RETURN AND COUPLED WITH INCREASED INSOLATION
HIGHS WILL REBOUND BACK INTO THE 80S. WE WILL THEN SEE SLIM STORM
CHANCES CREEP BACK INTO THE FORECAST THURSDAY NIGHT INTO FRIDAY AS
ONE OR MORE SUBTLE DISTURBANCES MOVE THROUGH THE QUASI-ZONAL FLOW
AND GRAZE THE AREA FROM THE NORTH. THE SUPPRESSED SOUTHWESTERN UPPER
RIDGE IS THEN FORECAST TO EXPAND NORTHWARD AND BRIDGE TO AN UPPER
HIGH CENTERED OVER FLORIDA THIS WEEKEND WHILE AT THE SAME TIME A
SHARP TROUGH MOVES STEADILY ACROSS THE NORTHERN TIER OF THE NATION.
THE BUILDING HEIGHTS AND PROLONGED SOUTHERLY FLOW WILL ALLOW
TEMPERATURES TO MODERATE BACK UP TO NEAR AVERAGE BY FRIDAY AND
SATURDAY. EVEN WITH THE RIDGE BUILDING MORE SQUARELY OVERHEAD...A
SUBTROPICAL MOISTURE FETCH ALONG WITH CONVERGENCE ALONG A SURFACE
TROUGH WILL KEEP LOW THUNDER CHANCES GOING ACROSS THE WESTERN
ZONES ON SATURDAY. THE NORTHERN STREAM SYSTEM WILL THEN SEND A
COLD FRONT SOUTHWARD INTO THE SOUTHERN PLAINS ON SUNDAY BEFORE
STALLING OUT SOMEWHERE NEARBY AND THEN WASHING OUT EARLY NEXT
WEEK. THIS FRONT WILL PROVIDE AT LEAST A SLIM SHOT OF ADDITIONAL
CONVECTION ON SUNDAY...THOUGH WITHOUT ANY UPPER SUPPORT COVERAGE
WOULD LIKELY BE NO BETTER THAN SCATTERED.
AFTER ANOTHER BRIEF AND LESS DRAMATIC COOL DOWN /THAN ON
WEDNESDAY/ WITH THE FRONT LATE THIS WEEKEND...HOTTER AND DRY
WEATHER SHOULD FOLLOW. THIS WILL OCCUR AS UPPER RIDGING IS
PROGGED TO AMPLIFY OVER THE SOUTHERN ROCKIES INTO THE SOUTHERN
HIGH PLAINS DURING THE EARLY AND MIDDLE PARTS OF NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 92 58 75 53 / 20 30 10 0
TULIA 91 60 74 54 / 20 40 20 0
PLAINVIEW 92 61 74 53 / 20 30 20 0
LEVELLAND 93 63 77 56 / 20 30 20 0
LUBBOCK 94 65 77 57 / 20 30 20 10
DENVER CITY 96 65 79 56 / 20 20 20 10
BROWNFIELD 94 65 79 56 / 20 30 20 10
CHILDRESS 96 67 78 58 / 20 40 30 10
SPUR 95 67 78 58 / 20 30 30 20
ASPERMONT 99 70 83 61 / 20 30 30 30
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
33/23
AREA FORECAST DISCUSSION
NWS AUSTIN/SAN ANTONIO TX
1242 AM CDT TUE AUG 18 2015
.AVIATION...
ISOLD SHRA/TSRA ARE POSSIBLE ALONG THE SEABREEZE WELL SOUTHEAST
OF I-35 TUESDAY AFTERNOON WITH NO IMPACT TO TAF SITES. VFR SKIES
START THE FORECAST. STRATUS WITH IFR/MVFR CIGS WILL DEVELOP
OVERNIGHT..18/07Z-10Z..ALONG THE ESCARPMENT INTO THE HILL COUNTRY
AND THEN SPREAD TO THE MOST OF THE REMAINDER OF SOUTH CENTRAL
TEXAS BY MORNING. CLOUDS LIFT AND BECOME FEW-SCT VFR CUMULUS LATE
MORNING THROUGH EVENING. STRATUS WITH IFR/MVFR CIGS REDEVELOPS
TUESDAY NIGHT AFTER 19/06Z. S TO SE WINDS LESS THAN 10 KTS
INCREASE TO 10 TO 15 KTS ON TUESDAY...BACK WITH PASSAGE OF THE
SEABREEZE MID AFTERNOON INTO EVENING...AND THEN DECREASE TUESDAY
NIGHT.
&&
.PREV DISCUSSION... /ISSUED 830 PM CDT MON AUG 17 2015/
UPDATE...
CONVECTION HAS ENDED ACROSS THE AREA WITH THE LOSS OF DIURNAL
HEATING. AN UPDATE TO THE TEXT...GRAPHIC...AND GRID FORECAST WAS
JUST SENT TO RE-TREND VARIABLES THROUGH 12Z TUESDAY...BUT NO MAJOR
CHANGES TO THE PREVIOUS FORECAST.
PREV DISCUSSION... /ISSUED 643 PM CDT MON AUG 17 2015/
UPDATE...00Z AVIATION UPDATE BELOW.
AVIATION...VFR CONDITIONS CONTINUE THROUGH THE EVENING HOURS.
ISOLATED SHRAS WILL END AROUND SUNSET. PATCHES OF MVFR MORNING
STRATUS WERE EVIDENT THIS MORNING...AND COVERAGE SHOULD BE
SLIGHTLY GREATER OVERNIGHT AND TUESDAY MORNING. NAM BUFR SOUNDINGS
COMBINED WITH 950MB MOISTURE PROGS FROM VARIOUS MODELS INDICATE
STRATUS DEVELOPMENT ALONG THE SOUTHERN EDGE OF THE ESCARPMENT
NEAR SAT AROUND 08Z...POSSIBLY SPREADING INTO AUS TERMINAL 09Z-12Z
AS LOW LEVEL FLOW VEERS SLIGHTLY MORE SW. THERE IS A CHANCE THAT
DRT COULD SEE A PERIOD OF MVFR CEILINGS 13Z-16Z PER NAM BUFR
SOUNDINGS AND HRRR SOLUTIONS...ALTHOUGH CONFIDENCE IS LOWER THAN
I-35 SITES. STRATUS WILL SCATTER OUT QUICKLY LATE MORNING WITH VFR
CONDITIONS AGAIN TUE AFTERNOON. ISOLATED SHRAS AGAIN POSSIBLE TUE
DURING THE MID AFTERNOON AND EVENING HOURS EAST OF I-35. THESE ARE
NOT EXPECTED TO IMPACT THE I-35 TAF SITES. S AND SE FLOW LATE TUE
MORNING AND AFTERNOON WILL BE SLIGHTLY STRONGER...WITH SOME GUSTS
NEAR 20 KTS POSSIBLE.
PREV DISCUSSION... /ISSUED 255 PM CDT MON AUG 17 2015/
SHORT TERM (TONIGHT THROUGH TUESDAY)...
NO MAJOR HIGHLIGHTS THROUGH TUESDAY WITH NEAR NORMAL CONDITIONS
AND LOW END RAIN CHANCES FOR THE COASTAL PLAINS.
WATER VAPOR AND RUC ANALYSIS REVEAL A SHEAR AXIS AND MID TO UPPER
LEVEL LOW ACROSS THE MID MISSISSIPPI VALLEY EXTENDING SOUTHWEST
ALONG THE TEXAS COAST. THIS FEATURE ALONG WITH AFTERNOON
INSTABILITY WILL GOVERN THE WEATHER PATTERN THROUGH
TUESDAY BY KEEPING TEMPERATURES NEAR NORMAL AND ONLY 20-30%
TSTORM CHANCES ALONG THE COAST WHERE THE SEA-BREEZE CONVERGENCE
WILL BE MORE ACTIVE. PRECIPITABLE WATER AMOUNTS CURRENTLY RANGE
FROM 1.0" TO 1.6" FROM THE RIO GRANDE VALLEY TOWARDS THE COASTAL
PLAINS. THESE VALUES ARE ABOUT 0.5 TO 1 STANDARD DEVIATION BELOW
NORMAL AND THUS RESULTING IN LIMITED SHOWER/STORM ACTIVITY ACROSS
A MAJORITY OF THE REGION. THIS PATTERN WILL CONTINUE THROUGH
TOMORROW WITH ONLY LIMITED SHOWERS AND A FEW THUNDERSTORMS ALONG
THE COASTAL PLAINS.
LONG TERM (WEDNESDAY THROUGH MONDAY)...
THE LOW-LEVEL PATTERN WILL CHANGE UP MID TO LATE WEEK AS A
BOUNDARY APPROACHES THE REGION FROM THE NORTH WITH HIGHER RAIN
CHANCES AND LOWER MAX HIGH TEMPERATURES LIKELY.
BY MID-WEEK...GLOBAL MODELS AGREE THAT A LARGE LONG WAVE TROUGH
WILL DEVELOP OVER THE CENTRAL CONUS AND WITH ADDITIONAL SHORTWAVE
TROUGH SUPPORT OVER NEW MEXICO AND TEXAS...A PSEUDO COLD FRONT
WILL APPROACH THE REGION FROM THE NORTH LATE WEDNESDAY INTO
THURSDAY MORNING. WEDNESDAY WILL REMAIN NEAR NORMAL TEMPERATURE
WISE WITH HIGHS STILL IN THE MID TO UPPER 90S AREA WIDE AND LOWER
RAIN CHANCES OF 20-40% AREA WIDE. RAIN CHANCES WILL INCREASE GOING
THROUGH THE OVERNIGHT INTO THURSDAY MORNING FOR THE HILL COUNTRY
AS THE BOUNDARY APPROACHES BUT THEN LOOKS TO STALL. WITH THE
SHEAR AXIS OVER TOP OF THE FRONT...THIS SET-UP SHOULD PROVIDE
AREAS WITH MORE CLOUDS AND WITH PWATS INCREASING TO 1.4" TO
1.8"...MORE WIDESPREAD RAIN CHANCES OF AT LEAST 50% APPEAR A
NOMINAL ROUTE TO GO FOR THURSDAY AND CONTINUING INTO FRIDAY. 12Z
GFS APPEARS TO HAVE A MESOSCALE FEEDBACK ISSUE BY PRODUCING A QPF
BULLSEYE JUST SOUTH OF THE REGION AS IT CONSOLIDATES THE UPPER LOW
INTO A TIGHTER CLOSED LOW. SINCE THIS IS THE FIRST ADVERTISEMENT
OF THIS EVOLUTION...WILL SIDE MORE WITH CONSISTENCY AND THE EC
WHICH ALSO LINGERS THE MID LEVEL ENERGY OVER THE REGION. THE EXTRA
CLOUDS SHOULD RESULT IN MAX HIGHS BEING REDUCED TO LOW TO MID 90S
BEING QUITE PLAUSIBLE.
OVER THE WEEKEND...RAIN CHANCES LOOK TO DECREASE AS THE FRONT
WASHES OUT AND SHIFTS NORTH WITH A SUBTROPICAL RIDGE SLOWLY
INCREASING ITS INFLUENCE ACROSS THE NORTH GULF.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 77 98 76 94 76 / 10 20 50 40 20
AUSTIN BERGSTROM INTL AIRPORT 74 97 74 94 74 / 10 20 50 50 20
NEW BRAUNFELS MUNI AIRPORT 76 99 76 93 75 / 10 20 40 50 30
BURNET MUNI AIRPORT 75 96 74 92 74 / - 20 50 30 10
DEL RIO INTL AIRPORT 77 100 78 95 75 / - 20 30 40 20
GEORGETOWN MUNI AIRPORT 77 98 75 93 75 / 10 20 50 40 20
HONDO MUNI AIRPORT 74 98 76 94 74 / - 20 30 50 20
SAN MARCOS MUNI AIRPORT 77 97 76 93 75 / 10 20 40 50 20
LA GRANGE - FAYETTE REGIONAL 78 98 76 93 76 / 20 30 40 50 30
SAN ANTONIO INTL AIRPORT 78 97 78 94 77 / - 20 40 50 30
STINSON MUNI AIRPORT 77 99 78 95 76 / 10 20 30 50 30
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE/AVIATION...04
SYNOPTIC/GRIDS...HAMPSHIRE
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
914 PM EDT WED AUG 19 2015
.SYNOPSIS...
MOIST SOUTHERLY FLOW AHEAD OF AN APPROACHING COLD FRONT AND WEAK
SHORTWAVE DISTURBANCES ALOFT WILL COMBINE TO PRODUCE MORE ROUNDS
OF SHOWERS AND THUNDERSTORMS OVERNIGHT INTO THURSDAY. THE COLD
FRONT WILL REACH THE MID ATLANTIC BY THURSDAY EVENING...AND
EVENTUALLY DEPART BY FRIDAY. COOLER AND DRIER AIR SHOULD ARRIVE BY
THE UPCOMING WEEKEND.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 840 PM EDT WEDNESDAY...
CLUSTERS OF SLOW MOVING SHOWERS/STORMS CONTINUE OVER THE SOUTH AND
EAST THIS EVENING WITHIN AN AREA OF VERY HIGH SURFACE THETA-E
SUPPORTED BY WEAK LOW LEVEL CONVERGENCE PER SOUTH/SE FLOW. EXPECT
THIS BROKEN AXIS OF CONVECTION TO GRADUALLY SHIFT EAST OF THE
AREA AROUND MIDNIGHT...BUT MAY STILL SEE ADDED SHRA POP UP ESPCLY
OVER THE SOUTH/SW AHEAD OF ANOTHER WAVE TO SW AND BEFORE WEAK
INSTABILITY FADES. THIS IN LINE WITH THE LATEST HRRR WHICH KEEPS
MOST COVERAGE WEST OF THE CWA ONCE THE CURRENT ACTIVITY MOVES
EAST. THUS TRIMMED BACK POPS OVER THE EAST AFTER MIDNIGHT WHILE
LEAVING CHANCE COVERAGE IN OVER PARTS OF THE SOUTH/WEST GIVEN SUCH
HIGH PWATS AND OLD OUTFLOW AROUND. FOG DEPENDENT UPON SEEING SOME
CLEARING OF DEBRIS CLOUDS OVERNIGHT WHICH FOR NOW LOOK A BIT MORE
WIDESPREAD THAN EARLIER THOUGHT PER IR PICS SO WONT BOOST FOG
COVERAGE TOO MUCH MORE THAN CURRENTLY ADVERTISED. OTRW ANOTHER
WARM/MUGGY NIGHT WITH LOWS MID/UPPER 60S MOUNTAINS TO LOW 70S IN
PARTS OF THE EAST.
PREVIOUS DISCUSSION AS OF 345 PM EDT WEDNESDAY...
SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE TO POP UP OVER THE
CWA...BUT COVERAGE OF THUNDER REMAINS LIMITED AT THIS TIME.
APPARENTLY...THE POOR LAPSE RATES AND CONSIDERABLE CLOUD COVER ARE
STILL TRYING TO HOLD BACK THE GROWTH OF CAPE. WITH SEVERAL MORE
HOURS OF SUNSHINE TO GO...IT SEEMS INEVITABLE THAT THE CONVECTIVE
ACTIVITY WILL ONLY INCREASE IN COVERAGE AS THE ATMOSPHERE
DESTABILIZES WITH TIME. THE SHOWERS AND THUNDERSTORMS ARE MOVING
TO THE NORTHEAST AND ARE NOT ANCHORING TO THE BLUE RIDGE...WHICH
IS KEEPING ANY THREAT OF LOCALIZED FLOODING IN CHECK FOR NOW.
HOWEVER...THIS THREAT REMAINS IN PLACE THROUGH THE EVENING...AND
HEAVY DOWNPOURS ARE CERTAINLY POSSIBLE IN THE STRONGER STORMS
THANKS TO THIS TROPICAL-LIKE AIR MASS OVERHEAD. HIGH TEMPERATURES
WERE BUMPED UP A FEW MORE DEGREES FOR TODAY IN THIS UPDATE...DUE
TO SOME AREAS RECEIVING MORE AUGUST SUNSHINE THAN ANTICIPATED.
FOR TONIGHT...THE SHOWER AND THUNDERSTORMS SHOULD GRADUALLY WANE
AS THE PREFRONTAL SHORTWAVE DISTURBANCES MOVE EAST OF THE CWA. IT
WILL BE A MUGGY NIGHT WITH THICK CLOUD COVER OVERHEAD...BUT ANY
GAPS IN THE CLOUDS COULD LEAD TO THE QUICK FORMATION OF PATCHY FOG
FROM THE WET GROUND. A FEW SHOWERS COULD LINGER THROUGHOUT THE
NIGHT...BUT THIS ACTIVITY WILL INCREASE AGAIN BY THURSDAY...AS THE
COLD FRONT CROSSES THE APPALACHIAN MOUNTAINS. THERE REMAINS NO
EXPECTED THREAT OF SEVERE WEATHER DUE TO MOIST ADIABATIC LAPSE
RATES AND LIMITED HEATING. HOWEVER...LOCALIZED FLOODING MAY BE A
SOMEWHAT BIGGER CONCERN ON THURSDAY IF ENOUGH QPF IS REALIZED FROM
THE BANDS OF SHOWERS AND THUNDERSTORMS JUST AHEAD OF THE FRONT.
THE MODELS PORTRAY MORE WIDESPREAD RAINFALL COVERAGE THAN THE PAST
SEVERAL DAYS...SO LIKELY POPS WITH HIGHS REACHING THE UPPER 70S TO
THE UPPER 80S ARE EXPECTED.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
AS OF 245 PM EDT WEDNESDAY...
THURSDAY NIGHT A COLD FRONT WILL CONTINUE ACROSS THE AREA...BRINGING
A WEST TO EAST END OF THE PRECIPITATION WITH ITS PASSAGE. LINGERING
SHOWERS WILL STILL BE POSSIBLE ACROSS THE SOUTHEAST PART OF THE
FORECAST AREA DURING THE EARLY MORNING HOURS OF FRIDAY. HIGH
PRESSURE WILL START TO WORK ITS WAY INTO THE AREA BY LATE THURSDAY
NIGHT. PATCHY FOG IS EXPECTED IN THE TYPICALLY MOUNTAIN AND RIVER
VALLEYS...ESPECIALLY THOSE AREA THAT RECEIVED THE MOST RAINFALL ON
THURSDAY AND THURSDAY EVENING. DRIER...LOWER DEW POINT AIR WILL MOVE
INTO THE REGION ALLOWING FOR LOW TEMPERATURES SOME 5 TO 10 DEGREES
COOLER THAN THOSE EXPECTED TONIGHT. EXPECT LOWS TO RANGE FROM THE
MID 50S TO NEAR 60 ACROSS THE MOUNTAINS WITH MID TO UPPER 60S ACROSS
THE PIEDMONT.
HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION THROUGH
SATURDAY. MOST THE REGION WILL BE PRECIPITATION FREE WITH LIMITED
CLOUD COVER. THE ONE AREA THAT MAY SEE SOME LATE DAY ISOLATED
SHOWERS WILL BE THE NORTHERN MOUNTAINS OF NORTH CAROLINA...AND
NEIGHBORING SECTIONS ALONG THE BLUE RIDGE OF SOUTHWEST
VIRGINIA...SOUTHWEST OF GALAX THANKS TO WEAK CONVERGENCE DUE TO
DIFFERENTIAL HEATING. TEMPERATURES WILL TREND SLIGHTLY COOLER
THROUGH THE PERIOD. FRIDAY NIGHT AND SATURDAY NIGHT LOWS WILL BE IN
THE LOW TO MID 50S ACROSS THE MOUNTAINS WITH LOWER 60S ACROSS THE
PIEDMONT. HIGHS WILL RANGE FROM THE UPPER 70S TO AROUND 80 ACROSS
THE MOUNTAINS WITH LOWER 80S ACROSS THE PIEDMONT. LATE NIGHT RIVER
AND MOUNTAIN VALLEY FOG WILL CONTINUE TO BE POSSIBLE.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 300 PM EDT WEDNESDAY...
HIGH PRESSURE WILL CONTINUE OVER THE AREA...BUT ITS AXIS WILL SHIFT
EAST THROUGH MONDAY. THIS WILL ALLOW FOR HIGHER DEW POINTS TO WORK
THEY WAY NORTH THROUGH THE WESTERN PORTION OF THE FORECAST AREA. LOOK
FOR A GREATER EXPANSE OF ISOLATED SHOWERS...AND POSSIBLY A FEW
STORMS SUNDAY AFTERNOON. BY MONDAY AFTERNOON...AN APPROACHING COLD
FRONT WILL BE ON OUR WESTERN DOORSTEP. ISOLATED TO SCATTERED
COVERAGE OF SHOWERS AND STORMS ACROSS A GREAT PERCENTAGE OF THE
REGION IS EXPECTED. THE BEST COVERAGE WILL BE IN THE WEST...NEAREST
THE FRONT. TEMPERATURES WILL TREND MILDER THROUGH MONDAY...WITH
HIGHS EXPECTED TO BE AROUND 80 IN THE MOUNTAINS AND THE MID TO UPPER
80S ACROSS THE PIEDMONT.
ON TUESDAY...GUIDANCE VARIES AS TO HOW MUCH PROGRESSION THE FRONT
WILL HAVE MADE HEADWAY ACROSS OUR AREA. OUR FORECAST WILL CONTINUE
TO LEAN ON THE SIDE OF SLOWNESS...KEEPING THE POTENTIAL FOR ISOLATED
SHOWERS AND STORMS IN THE FORECAST FOR TUESDAY...THE GREATEST
POTENTIAL IN THE SOUTHEAST PARTS OF THE REGION.
BY WEDNESDAY...HIGH PRESSURE WILL AGAIN BE MOVING INTO OUR
REGION...WITH THE START OF A DRYING. AT BEST ISOLATED SHOWERS ARE
EXPECTED ACROSS THE FAR SOUTHEAST PORTION OF THE FORECAST AREA. HIGH
TEMPERATURES WILL BE COMPARABLE TO THOSE OF TUESDAY.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
AS OF 645 PM EDT WEDNESDAY...
BANDS AND CLUSTERS OF SHOWERS/STORMS CONTINUE TO BE WIDELY SCATTERED
ACROSS THE REGION THIS EVENING WITH THE MAJORITY AFFECTING SPOTS
FROM KLYH SOUTH TO AROUND KDAN. TIMING OF THIS ACTIVITY WOULD PUT
A PERIOD OF MVFR/IFR INTO KLYH AROUND 00Z/8PM AND PERHAPS KDAN
BETWEEN 01-03Z/9-11PM IF COVERAGE TO THE SOUTH HOLDS TOGETHER.
ELSW MAY INIT WITH A VCSH OR TEMPO GROUP TO COVER ADDED POP UP
SHRA/TSRA GIVEN LINGERING INSTABILITY/OUTFLOW ALTHOUGH EXPECTING
MOST OTHER LOCATIONS TO REMAIN DRY INTO LATE EVENING.
AS CONVECTIVE ACTIVITY GRADUALLY WANES OVERNIGHT...EXPECT SOME FOG
AND STRATUS TO FILL IN UNDER EXITING RESIDUAL DEBRIS CLOUDS LATE.
THIS SUPPORTS A BETTER LIKELIHOOD OF DENSE FOG IN THE VALLEY
LOCATIONS ESPCLY THOSE THAT SAW EARLIER SHOWERS WITH IFR OR LIFR
LIKELY. SOME SPOTTY FOG POSSIBLE AS WELL AT KROA WHERE GOT
CLIPPED BY A SHRA EARLIER...AND PERHAPS KBLF PENDING CLOUDS. MVFR
FOG POSSIBLE EAST WITH IFR AT KLYH GIVEN CURRENT CONVECTION TO
PASS ACROSS...AND ONLY MVFR AT KDAN IF THEY DON`T SEE ADDED SHRA
OVER THE NEXT FEW HOURS.
EARLY LOW CLOUDS AND FOG SHOULD FADE BY MID MORNING BUT MAY TAKE
LONGER IN SPOTS IF LIGHTER SHOWERS OR DEBRIS CLOUDS AHEAD OF THE
COLD FRONT TO THE WEST ARRIVE EARLY ON. OTRW TREND OF MVFR-IFR
EARLY GIVING WAY TO VFR UNDER A DEVELOPING CU FIELD BY AFTERNOON.
ISOLATED SHOWERS COULD POP UP IN THE MORNING FAR WEST AS THE COLD
FRONT DRAWS NEARER WITH POTENTIAL FOR A BAND OF SOMEWHAT DEEPER
CONVECTION JUST AHEAD OF THE FRONT DURING THE AFTERNOON. THUS
GIVEN SUCH HIGH PROBABILITY OF SEEING SHRA/TSRA IN THE AFTERNOON
INCLUDING A MVFR PREVAILING SHRA GROUP FROM WEST TO EAST THURSDAY
AFTERNOON INCLUDING A VCTS MENTION DESPITE RATHER MEAGER FORECAST
INSTABILITY UNDER WESTERLY FLOW ALOFT.
EXTENDED AVIATION DISCUSSION...
A COLD FRONT WILL PUSH ACROSS THE MID ATLANTIC ON THURSDAY
EVENING...AND BRING ANOTHER PERIOD OF SHOWERS AND THUNDERSTORMS
MAINLY TO THE EASTERN SITES. MVFR/IFR CONDITIONS AND HEAVY
DOWNPOURS ARE LIKELY WITHIN THE STRONGER STORMS. ONCE THE FRONT
MOVES TOWARD THE VA/NC BORDER...SOMEWHAT COOLER AND DRIER AIR
ALOFT SHOULD INFILTRATE THE REGION. THERE IS STILL SOME QUESTION
AS TO HOW QUICKLY THIS FRONT MOVES SOUTH OF THE REGION BY FRIDAY
MORNING. THE MODELS REMAIN OPTIMISTIC THAT IT WILL...BUT IF IT
DOES NOT...LOW CEILINGS AND PATCHY FOG MAY REAPPEAR FOR ANOTHER
NIGHT.
DEPENDING ON HOW FAR SOUTH THE FRONT PROGRESSES BY MIDDAY
FRIDAY...THERE MAY STILL BE A FEW LINGERING SHOWERS SOUTH OF
DAN/BLF. OTHERWISE...SITES TO THE NORTH MAY SEE NO RAIN AND VFR
CONDITIONS. CONFIDENCE IN VFR FOR ALL TAF SITES INCREASES ON FRIDAY
NIGHT...AS HIGH PRESSURE ARRIVES FROM THE NORTH. GOOD FLYING
WEATHER SHOULD PERSIST THROUGH THE WEEKEND. BY MONDAY...A WEAK
COLD FRONT MAY ARRIVE FROM THE WEST TO BRING A CHANCE OF SHOWERS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/PW
NEAR TERM...JH/PW
SHORT TERM...DS
LONG TERM...DS
AVIATION...JH/PW
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
142 AM EDT TUE AUG 18 2015
.SYNOPSIS...
WEAK HIGH PRESSURE ACROSS THE REGION TONIGHT WILL WEAKEN AND
SLIDE EAST TO OFFSHORE THE MID ATLANTIC COAST ON TUESDAY. A COLD
FRONT IS EXPECTED TO DRIFT SOUTHEAST TOWARD THE REGION WEDNESDAY
INTO THURSDAY BEFORE CROSSING INTO THE AREA THURSDAY NIGHT. THIS
WILL RESULT IN MULTIPLE PERIODS OF SHOWERS AND STORMS THROUGH
THURSDAY BEFORE DRIER AIR WORKS IN BEHIND THE PASSING FRONT ON
FRIDAY.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 825 PM EDT MONDAY...
EVENING SOUNDINGS SHOW QUITE A BIT OF MOISTURE AND INSTABILITY
HAVING MADE A RETURN TO THE REGION TONIGHT WITH DEEPER SOUTHERLY
FLOW AND PWATS NEAR 1.5 INCHES. HOWEVER FAINT CAP ALOFT ALONG WITH
MOST LIFT BEING WEST OF THE MOUNTAINS WITH THE UPSTREAM
IMPULSE...HAS KEPT MOST ORGANIZED CONVECTION CONFINED TO THE FAR
WEST ON THE LEADING EDGE OF THE PCPN SHIELD AND WITH RESIDUAL
OUTFLOW. LATEST ANALYSIS SHOWING A DECENT AMOUNT OF LEFTOVER
INSTABILITY SPCLY BLUE RIDGE EAST SO TRICKY IN REGARDS TO WHETHER
OR NOT COVERAGE WILL FILL IN OVER THE NEXT FEW HOURS DESPITE LOSS
OF HEATING. LATEST HRRR REMAINS QUITE WET IN DEVELOPING SHRA/TSRA
ACROSS MUCH OF THE WEST OUT TO THE BLUE RIDGE BY MIDNIGHT WITH
SOME OF THIS COVERAGE HEADING EAST INTO THE PIEDMONT BEFORE
DAYBREAK. THIS LOOKS A BIT OVERDONE BUT GIVEN COVERAGE DEVELOPING
ACROSS THE SW AND LESS WORKED OVER NATURE TO THINGS FROM THIS
AFTERNOON WILL SPEED UP LIKELY POPS WEST AND EDGE HIGHER CHANCES
EAST OVERNIGHT. TEMPS TO REMAIN MUCH MORE ON THE WARM/MUGGY SIDE
OVERNIGHT GIVEN THE INCREASE IN MOISTURE...AND EXPECT SOME EASTERN
LOCATIONS TO STAY ABOVE 70 SO BUMPING UP LOWS A FEW DEGREES
OVERALL.
PREVIOUS DISCUSSION AS OF 235 PM EDT MONDAY...
STICKING CLOSER TO THE LOCAL WRF/HRRR THIS AFTERNOON INTO THE
EVENING WITH SCATTERED SHOWER AND STORM COVERAGE FROM THE BLUE
RIDGE WEST. COVERAGE AT THE MOMENT IS WIDELY SCATTERED WITH BEST
INSTABILITY SITUATED OVER THE NC/VA FOOTHILLS...WHERE SOME CELLS
HAD DEVELOPED INTO THUNDERSTORMS. MEAN FLOW WILL STAY WEAK SO
HEAVY RAINERS WILL OCCUR.
THIS ACTIVITY DIMINISHES SOMEWHAT THIS EVENING WITH LOSS OF
HEATING...BUT OVERNIGHT THE SHORTWAVE FROM SOUTHERN ILLINOIS TO MID
TENNESSEE WILL WORK NORTHEAST ACROSS THE MOUNTAINS INCREASING LIFT
AND WITH HIGHER PWATS...SHOULD SEE AN AREA OF SHOWERS...MAYBE A
RUMBLE OF THUNDER TRACK INTO THE MOUNTAINS. HAVE LIKELY TO SOME
CATEGORICAL POPS MAINLY WEST OF A COVINGTON VA TO MOUNT AIRY NC
LINE...WITH QUICKLY DIMINISHING POPS TO SLIGHT CHANCE EAST OF
LYNCHBURG/DANVILLE UNDERNEATH THE SFC HIGH.
THE FLOW WILL INCREASE AT 8H SO SHOWERS SHOULD BE MOVING A LITTLE
FASTER THAN THIS AFTERNOON. WITH PLENTY OF CLOUDS LOW TEMPS WILL BE
ELEVATED IN THE MID 60S TO AROUND 70.
TUESDAY...SHORTWAVE LIFTS NORTHEAST...BUT THERE IS SOME WEAK
UPPER SUPPORT AND DIFFLUENCE REMAINING TO KEEP LIKELY POPS GOING
ACROSS MOST OF THE FORECAST AREA. STORM CHANCE WILL BE LIMITED BY
CLOUD COVER BUT THINK THE UPPER SUPPORT IS ENOUGH TO HAVE THUNDER
INTO THE REGION BY AFTERNOON. HIGHS WILL BE TEMPERED BY CLOUD
COVER BUT WILL BE HUMID. TEMPS WILL RUN FROM THE LOWER TO MID 70S
OVER THE HIGHER ELEVATIONS AND ADJACENT VALLEYS IN THE WEST...WITH
UPPER 70S TO LOWER 80S ACROSS THE FOOTHILLS AND PIEDMONT INCLUDING
THE ROANOKE VALLEY.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
AS OF 230 PM EDT MONDAY...
THE CWA WILL BE EXPOSED TO SOUTHERLY FLOW FROM THE COMBINATION OF
HIGH PRESSURE OFFSHORE...AND AN APPROACHING COLD FRONT IN THE PLAINS
DURING TUESDAY NIGHT INTO WEDNESDAY. SOME CONVECTIVE ACTIVITY MAY
NOT FADE OUT SO QUICKLY IN THE NIGHTTIME HOURS DUE TO INCREASING
INSTABILITY AND MOISTURE AHEAD OF THE FRONT. AS A RESULT...MOST OF
THIS FORECAST PERIOD WILL BE EMBEDDED IN CHANCES OF SHOWERS AND
THUNDERSTORMS...WITH SOME DIURNAL VARIATION IN THE THUNDERSTORM
COVERAGE. DURING WEDNESDAY AFTERNOON AND EVENING...POPS WERE KEPT
HIGHEST MAINLY WEST OF THE BLUE RIDGE.
AS THE COLD FRONT DRAWS NEARER ON THURSDAY...LOOK FOR COVERAGE AND
ACTIVITY OF THE SHOWERS AND THUNDERSTORMS TO INCREASE MORE
SIGNIFICANTLY...ESPECIALLY WEST OF THE BLUE RIDGE. BOTH THE 12Z
ECMWF AND GFS MODELS SHOW THE EXPECTED FRONTAL PASSAGE AROUND
THURSDAY EVENING. ALTHOUGH SEVERE WEATHER THREAT PROJECTIONS APPEAR
LOW FROM SPC...THERE WILL BE A THREAT OF HEAVY RAIN HITTING THE SAME
LOCATIONS REPEATEDLY ON WEDNESDAY AND THURSDAY...WHICH COULD INDUCE
LOCALIZED FLOODING. AFTER THE FRONT CLEARS THE CWA BY EARLY FRIDAY
MORNING...CLOUD COVER AND POPS WILL GRADUALLY LESSEN.
TEMPERATURES DO NOT SHOW MUCH APPRECIABLE CHANGE BEFORE THE COLD
FRONT ARRIVES. THE AIR MASS WILL BECOME INCREASINGLY HUMID ON
WEDNESDAY AND THURSDAY...WHERE LOW TEMPERATURES MAY FAIL TO DROP
BELOW THE MID 60S IN THE MOUNTAINS...AND THE UPPER 60S TO THE LOWER
70S IN THE PIEDMONT. HIGHS SHOULD VARY FROM THE UPPER 70S TO THE
UPPER 80S...WHICH IS WELL IN AGREEMENT WITH THE MOS GUIDANCE. LOWS
ON FRIDAY MORNING WILL BE A LITTLE COOLER THANKS TO THE FRONTAL
PASSAGE...AS TEMPERATURES MAY HIT 60 DEGREES OR LOWER IN THE HIGHER
ELEVATIONS.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 218 PM EDT MONDAY...
LOW CONFIDENCE FORECAST DURING THE PERIOD AS MODELS ARE AGGRESSIVELY
PUSHING A COLD FRONT SOUTH INTO THE CAROLINAS ON FRIDAY. THERE ARE
SEVERAL REASONS REGARDING OUR LOW CONFIDENCE. ONE BIG FACTOR IS THE
TIME OF YEAR. MODELS TEND TO PUSH FRONTS TOO FAR SOUTH DURING
AUG-OCT TIME FRAME. ANOTHER DEALS WITH A WEAK SURFACE HIGH
PRESSURE BEHIND THE FRONT AND A STRONG UPPER LEVEL RIDGE ACROSS
THE GULF STATES. THE SURFACE FRONT COULD PUSH SOUTH INTO CENTRAL
NORTH CAROLINA...HOWEVER MID AND UPPER LEVEL MOISTURE WILL KEEP
CLOUDS AND THE CHANCE FOR RAIN IN THE AREA ONGOING INTO THE
WEEKEND. SINCE THIS IS A WEAK SURFACE HIGH/WEDGE...BOUNDARY LIKELY
TO RETREAT NORTH...KEEPING THE CHANCES FOR SHOWERS IN THE AREA
THROUGH THE WEEKEND. THE THREAT FOR SHOWERS AND THUNDERSTORMS
INCREASES MONDAY AS A STRONG COLD FRONT APPROACHES FROM THE WEST.
ALONG WITH THE LOW CONFIDENCE FORECAST...WE WILL KEEP TEMPERATURES
CLOSE TO SEASONAL LEVELS THROUGH THE PERIOD. THE COOLEST OF MAY BE
SATURDAY AND THE WARMEST MONDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 140 AM EDT TUESDAY...
AS OF 140 AM EDT...AREAS OF RAIN WITH EMBEDDED HEAVIER SHOWERS
AND ISOLATED THUNDERSTORMS HAVE LIFTED NORTH AND EAST AND HAVE
OVERSPREAD MOST OF THE MOUNTAINS AND FOOTHILLS. THIS AREA
ASSOCIATED WITH INCREASING MOISTURE ADVECTION AND FORCING WITH
APPROACH OF WEAK UPSTREAM SHORT WAVE TROF. SHOWERS LIKELY TO
CONTINUE TO IMPACT OR MOVE INTO ALL TERMINAL FORECAST SITES
OVERNIGHT.
AS LOWER TROPOSPHERE GRADUALLY SATURATES...EXPECT TO SEE GRADUAL
REDUCTION OF CEILINGS AND VISIBILITIES IN MOST MOUNTAIN LOCATIONS
INTO MVFR RANGE...PERHAPS INTO IFR RANGE ALONG/NEAR HIGHER MOUNTAIN
RIDGES AND ACROSS THE IMMEDIATE EAST FLANKS OF THE BLUE RIDGE.
OUT ACROSS THE PIEDMONT...MOST NOTABLY AT KLYH AND KDAN...DIP INTO
MVFR RANGE POSSIBLE LATER TONIGHT...BUT PROBABILITY OF SUCH AN
OCCURRENCE NOT AS HIGH AS POINTS FURTHER WEST.
PERIODIC ROUNDS OF SHOWERS WITH ISOLATED ELEVATED THUNDER LIKELY
TO CONTINUE ON TUESDAY AS RIPPLES OF ENERGY CONTINUE TO TRAVERSE
THE REGION WITHIN AN AXIS OF TROPICAL MOISTURE. CONTINUED THREAT
OF PRECIPITATION AND GOOD LOW LEVEL MOISTURE ON WEAK UPSLOPING
WINDS MAY DELAY GRADUAL IMPROVEMENT BACK TO VFR CONDITIONS AT MOST
TERMINAL FORECAST UNTIL LATE MORNING/EARLY AFTERNOON...WITH
IMMEDIATE EAST FLANKS OF THE APPALACHIANS/BLUE RIDGE PERHAPS NOT
MIXING UP/BACK TO VFR UNTIL MID-LATE AFTERNOON DUE TO PERSISTENT
WEAK UPSLOPING WIND. HOWEVER...PLENTY OF CLOUDS IN 3000-5000 RANGE
SHOULD OFFSET EXTENT OF DAYTIME HEATING SUCH THAT MOST INSTABILITY
REMAINS PROGGED TO THE SOUTH AND WEST...SO NOT INCLUDING ANY
MENTION OF THUNDER THREAT AT ANY TERMINAL FORECAST POINT AT THE
PRESENT TIME.
EXPECT SHOWERS TO TAPER OFF TUESDAY NIGHT AS UPPER SUPPORT EXITS
AND THE REGION MOVES INTO A LULL BETWEEN THE PASSING IMPULSES AND
THE UPSTREAM COLD FRONT. LINGERING MOISTURE SHOULD MAKE FOR
WIDESPREAD SUB-VFR IN THE WAKE OF THE SHOWERS WITH LOTS OF STRATUS
AND FOG AROUND UNTIL LATE TUESDAY NIGHT.
EXTENDED AVIATION DISCUSSION...
WEDNESDAY THROUGH THURSDAY....SHOWERS AND THUNDERSTORMS...
INCLUDING SUB-VFR CONDITIONS...WILL BE MORE SCATTERED TO NUMEROUS
THANKS TO A SLOW MOVING FRONTAL BOUNDARY THAT WILL STALL JUST
NORTHWEST OF THE REGION. THIS BOUNDARY WILL ACT AS THE FOCUSING
MECHANISM FOR MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS
ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS FOLLOWED BY
PATCHY FOG DURING THE OVERNIGHTS.
WE WILL START TO DRY OUT SOME GOING INTO FRIDAY AS THE FRONT MOVES
SOUTHEAST...BUT SOME LINGERING ACTIVITY POSSIBLE OVER THE KDAN TO
KTNB CORRIDOR. SHOULD RETURN TO OVERALL VFR SATURDAY WITH THE
FRONT OFFSHORE AND WEAK HIGH PRESSURE ABOUT OVERHEAD FOR MUCH OF
THE DAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH
NEAR TERM...JH/WP
SHORT TERM...PW
LONG TERM...RCS
AVIATION...AMS/JH/WERT/WP
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
339 PM CDT TUE AUG 18 2015
.SHORT TERM...
.THIS EVENING...FORECAST CONFIDENCE HIGH.
A STRENGTHENING UPPER LOW OVER THE NORTHERN PLAINS IS PRODUCING
ONGOING SHOWERS AND THUNDERSTORMS OVER MN AND IA TODAY. THERE ARE A
LOT OF CLOUDS ASSOCIATED WITH THAT AND AN 850MB WARM FRONT OVER
NORTHERN WISCONSIN. SOUTHEAST WI IS SEEING A FEW BREAKS IN THE
CLOUDS TODAY WHICH IS HELPING TO INCREASE TEMPS TO AROUND 80 AND
BUILD CAPE TO AROUND 1000 J/KG.
A STRONG SHORTWAVE TROUGH CURRENTLY OVER NORTHEAST MO WILL MOVE UP
THROUGH IA AND WI LATE THIS AFTERNOON/EVENING. THE NOSE OF THE LOW
LEVEL JET /LLJ/ WILL LIFT UP TO THE WI/IL BORDER THIS AFTERNOON AND
LIKELY INTO SOUTH CENTRAL WI BEFORE SHIFTING EAST THIS EVENING. THE
CONVECTION OVER FAR WESTERN WI AND FAR EASTERN IOWA IS TRACKING NNE.
THE 19Z HRRR MODEL PICKED UP ON IT AND BRINGS A WEAKER VERSION OF IT
INTO MADISON AFTER 5 PM. IT STILL HAS THE MAIN CONVECTIVE LINE WITH
THE STRONG SHORTWAVE REACHING MADISON AROUND 01Z /8 PM. WE CANNOT
DISCOUNT THIS LATEST RUN AS IT MAY BE ON TO SOMETHING FOR HOW THIS
EVENING/S CONVECTION WILL EVOLVE.
A NW TO SE ORIENTED LINE OF THUNDERSTORMS IS PORTRAYED BY THE OTHER
CONVECTIVE ALLOWING MODELS /CAMS/. THEY LIFT IT NORTHEAST THROUGH
SOUTHERN AND EAST CENTRAL WI THIS EVENING. IT SHOULD REACH MADISON
BY 7 PM AND MILWAUKEE BY 9 PM. THE THUNDERSTORMS SHOULD BE OUT OF
SOUTHERN WI BY MIDNIGHT.
THE SHEAR WILL BE STRONG OVER SOUTH CENTRAL WI AS THE SHORTWAVE
ARRIVES. THE CAPE IS MODERATE NOW... BUT WILL BE LOWER THIS EVENING
DUE TO WARM AIR ADVECTION ALOFT AND SUBSEQUENT VERY WEAK MID LEVEL
LAPSE RATES. STILL... THERE MAY BE ENOUGH SHEAR TO DEVELOP A FEW
SUSTAINED UPDRAFTS THAT COULD PRODUCE LOW LEVEL MESOCYCLONES AND A
POSSIBLE TORNADO. THE TORNADO WATCH WAS ISSUED ALREADY THIS
AFTERNOON AND IT IS IN EFFECT UNTIL 10 PM FOR ALL BUT THE EASTERN
FORECAST AREA. THE MAIN THREAT FOR SEVERE STORMS IN SOUTH CENTRAL WI
IS NOT UNTIL AFTER 5 PM.
.OVERNIGHT AND WEDNESDAY...FORECAST CONFIDENCE HIGH.
THE SURFACE LOW WILL TRACK NORTH FROM WEST CENTRAL WI TO WESTERN
LAKE SUPERIOR ON WEDNESDAY. THIS WILL RESULT IN A STRONG PRESSURE
GRADIENT OVER SOUTHERN WISCONSIN AND GUSTY SOUTHWEST WINDS BEGINNING
EARLY WEDNESDAY MORNING. STEEP LOW LEVEL LAPSE RATES WILL LEAD TO
EXTENSIVE DIURNAL CUMULUS CLOUDS SO KEPT MAX TEMPS ON THE LOWER END
OF GUIDANCE.
&&
.WEDNESDAY NIGHT AND THURSDAY...FORECAST CONFIDENCE...HIGH
THE GFS BRINGS A CLOSED MID/UPPER LOW ACROSS LAKE SUPERIOR
WEDNESDAY NIGHT AS THE TROUGH AXIS EXITS FAR EASTERN WISCONSIN
TOWARDS SUNRISE. THE CLOSED LOW LIFTS INTO SOUTHERN CANADA
THURSDAY.
THE 850/700 MB RH INCREASES OVER SOUTH CENTRAL WISCONSIN EARLY
WEDNESDAY EVENING...AND OVER MUCH OF THE SOUTH WEDNESDAY NIGHT
WITH THE EDGE OF THE HIGHER RH NEAR THE ILLINOIS BORDER AREA. THIS
SHOULD BRING AN AREA OF CUMULUS/STRATOCUMULUS ACROSS MUCH OF THE
FORECAST AREA WEDNESDAY NIGHT THAT LIFTS NORTHEAST LASTER
THURSDAY.
THE WRAP AROUND PRECIPITATION MAINLY STAYS NORTHWEST OF THE
FORECAST AREA. HOWEVER LOW LEVEL LAPSE RATES ARE FAIRLY STEEP SO
AN ISLOATED SHOWER COULD FORM THURSDAY.
WEST WINDS WILL BE BRISK AND WITH THE STEEP LAPSE RATES...GUSTS
TO 30 MPH IS POSSIBLE.
.THURSDAY NIGHT AND FRIDAY...FORECAST CONFIDENCE...HIGH
A ZONAL FLOW AGAIN BRIEFLY DEVELOPS IN THE MID/UPPER LEVELS
ACROSS WISCONSIN WITH THE MAIN JET ACROSS SOUTHERN CANADA. ANOTHER
SHORTWAVE DROPS INTO THE NORTHERN ROCKIES LATE FRIDAY.
THE NAM...GFS AND ECMWF ARE DRY.
.LONG TERM...
.FRIDAY NIGHT AND SATURDAY...FORECAST CONFIDENCE...HIGH
THE MID/UPPER TROUGH EXITS THE NORTHERN ROCKIES AND MOVES INTO THE
NORTHERN PLAINS WITH A WEAK RIDGE OVER SOUTHERN WISCONSIN.
BOTH THE 12Z GFS AND 00Z ECMWF KEEP A LOW OVER THE PLAINS WITH
PRECIPITATION STILL WELL OFF TO THE WEST.
.SUNDAY...FORECAST CONFIDENCE...MEDIUM
THE SHORTWAVE REACHES THE UPPER MISSISSIPPI VALLEY SUNDAY. THE
GFS IS JUST A LITTLE FARTHER NORTH AND SLIGHTLY SLOWER WITH THE
SHORTWAVE.
THE SURFACE LOW MOVES TO JUST NORTH OF LAKE SUPERIOR WITH A BAND
OF MODERATE PRECIPITATION WITH A TRAILING COLD FRONT.
.MONDAY...FORECAST CONFIDENCE...MEDIUM
THE SHORTWAVE MOVES ACROSS THE UPPER GREAT LAKES SUNDAY NIGHT AND
PUSHES IT NORTHEAST. THE 00Z ECMWF CUTS OFF THE LOW NEAR LAKE
SUPERIOR AND LAGS THE TROUGH INTO THE GREAT LAKES INTO MONDAY.
THE 00Z ECMWF HAS LOW PRESSURE REMAINING OVER THE UPPER GREAT
LAKES INTO MONDAY WITH THE HIGH OVER THE EASTERN PLAINS AND
WESTERN MISSISSIPPI VALLEY AREA...WHILE THE GFS BRINGS THE HIGH
ACROSS WISCONSIN.
&&
.AVIATION/00Z TAFS/...
EXPECT A NW TO SE ORIENTED LINE OF THUNDERSTORMS TO LIFT NORTHEAST
THROUGH SOUTHERN WI THIS EVENING. IT SHOULD ARRIVE IN MSN BY 6 PM
AND MKE BY 8 PM. THUNDERSTORMS COULD CONTAIN STRONG WIND GUSTS AND
SMALL HAIL. THERE IS ALSO A RISK FOR A TORNADO IN SOUTH CENTRAL WI.
ALL CONVECTION SHOULD BE OUT OF SOUTHERN WI BY MIDNIGHT. LOW CIGS
ARE POSSIBLE OVERNIGHT. EXPECT GUSTY SOUTHWEST WINDS ON WEDNESDAY AS
STRONG LOW PRESSURE TRACKS ACROSS NORTHWEST WI.
&&
.MARINE...
LOW PRESSURE WILL TRACK FROM WEST CENTRAL WISCONSIN TO WESTERN LAKE
SUPERIOR ON WEDNESDAY. EXPECT GUSTY SOUTHWEST WINDS BEGINNING EARLY
WEDNESDAY MORNING THAT CONTINUE THROUGH THURSDAY AFTERNOON. A SMALL
CRAFT ADVISORY IS IN EFFECT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TONIGHT/WEDNESDAY AND AVIATION/MARINE...MRC
WEDNESDAY NIGHT THROUGH TUESDAY...HENTZ
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1229 PM CDT TUE AUG 18 2015
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND WEDNESDAY
ISSUED AT 316 AM CDT TUE AUG 18 2015
THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A COLD
FRONT STRETCHING ACROSS SOUTHWEST TO EAST-CENTRAL WISCONSIN EARLY
THIS MORNING. A SECONDARY FRONT RUNS ACROSS SOUTHERN MINNESOTA TO
EASTERN LAKE SUPERIOR. WEAK FGEN COMBINED WITH LINGERING ELEVATED
INSTABILITY CONTINUE TO GENERATE SCATTERED SHOWERS ALONG BOTH
FRONTS. BETTER MOISTURE AND INSTABILITY RESIDES OVER IOWA AND THE
PLAINS WHERE THUNDERSTORMS ARE OCCURRING. LOOKING FURTHER
UPSTREAM...LOW PRESSURE IS DEVELOPING OVER NORTHEAST COLORADO AHEAD
OF A DIGGING SHORTWAVE TROUGH. PRECIP TRENDS ALONG THE FRONT AND
ASSOCIATED WITH THE SURFACE LOW ARE THE MAIN FORECAST CONCERNS.
MODELS HAVE SLOWED DOWN THE PROGRESSION OF SURFACE FEATURES
SOMEWHAT. THE GFS IS A CLEAR OUTLIER...PROBABLY DUE TO ITS RATHER
POOR INITIALIZATION. PREFER A BLEND OF THE NAM/ECMWF/GEM.
TODAY...AS LOW PRESSURE CONSOLIDATES OVER THE CENTRAL PLAINS...THE
PRIMARY COLD FRONT IS PROJECTED TO STALL OVER CENTRAL AND EAST-
CENTRAL WISCONSIN...NEAR OR JUST SOUTH OF THE SOUTHERN FORECAST AREA
BORDER. WILL PROBABLY SEE AN UPTICK OF SHOWER ACTIVITY THIS MORNING
WITH WEAK SHORTWAVES MOVING OVERHEAD. ONCE THESE SHORTWAVES PASS TO
THE EAST BY LATE MORNING...NORTHERN WISCONSIN MAY SEE A DRY PERIOD
SO REDUCED PRECIP CHANCES THERE. SCATTERED SHOWERS WILL STILL IMPACT
THE SOUTH...CLOSER TO THE STALLED FRONT. WILL LIKELY SEE SHOWERS AND
A FEW STORMS BECOME MORE WIDESPREAD OVER CENTRAL WISCONSIN LATE IN
THE AFTERNOON AS MID-LEVEL FLOW STRENGTHENS OVER THE BOUNDARY.
HIGHS RANGING FROM THE MID 60S NORTH TO MID 70S SOUTH.
TONIGHT...A STRONG AREA OF LOW PRESSURE WILL LIFT NORTHEAST TOWARDS
MINNEAPOLIS WHILE PUSHING A COLD FRONT INTO SOUTHWEST OR CENTRAL
WISCONSIN BY 12Z WED. AS LARGE-SCALE ASCENT INCREASES...SHOULD SEE
AREAS OF SHOWERS AND THUNDERSTORMS LIFT NORTHEAST ACROSS THE
FORECAST AREA. THE MOST POTENT SWATH OF STORMS SHOULD ARRIVE LATE
IN THE NIGHT AHEAD OF THE COLD FRONT AND CLOSED MID-LEVEL
CIRCULATION. THOUGH INSTABILITY WILL BE QUITE LOW...PWATS WILL BE
GREATER THAN 1.5 INCHES AND FORCING WILL BE EXCELLENT. WIND FIELDS
ALOFT WILL ALSO BE STRENGTHENING AS 850MB WINDS APPROACH 40-45 KTS.
THOUGH CONVECTION WILL LIKELY BE LOW TOPPED...ANY CONVECTION WILL BE
CAPABLE OF BRINGING DOWN THESE STRONGER WINDS. THEREFORE...A
MARGINAL RISK LOOKS REASONABLE FOR THE SOUTHWEST FORECAST AREA.
TEMPS WILL NOT FALL MUCH TONIGHT. LOWS AROUND 60 NORTH TO THE MID
60S SOUTH.
WEDNESDAY...LOW PRESSURE WILL SLOWLY MOVE NORTHEAST OVER FAR
NORTHWEST WISCONSIN AS THE COLD FRONT SWEEPS ACROSS NORTH-CENTRAL
AND NORTHEAST WISCONSIN. SHOWERS AND STORMS ARE A DECENT BET AHEAD
OF THE FRONT DURING THE MORNING...AND THE THREAT OF STRONG GUSTY
WINDS WILL ACCOMPANY ANY STORMS. THE FRONT WILL EXIT NORTHEAST
WISCONSIN BY MID TO LATE AFTERNOON ENDING ANY STORM THREAT. WRAP
AROUND LIGHT SHOWERS MAY SPREAD INTO NORTH-CENTRAL WISCONSIN BY
EARLY EVENING. HIGHS RANGING FROM THE MID 60S WEST TO MID 70S EAST.
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY
ISSUED AT 316 AM CDT TUE AUG 18 2015
THE STRONG COLD FRONT AND UPPER LEVEL CYCLONE...THAT WILL IMPACT
THE AREA IN THE SHORT TERM...WILL DEPART THE REGION ON THEIR WAY
TOWARD HUDSON BAY DURING THE LATTER HALF OF THE WEEK. THE CHANCE
FOR RAIN WILL DECREASE AS THESE FEATURES DEPART...ENDING BY 00Z
FRIDAY. UPPER FLOW ACROSS THE REGION BRIEFLY BECOMES ZONAL...THEN
SOUTHWEST AS A WEST COAST TROUGH TRAVERSES THE CONUS. ANOTHER
COLD FRONT IS FORECAST TO MOVE ACROSS THE REGION OVER THE WEEKEND
ALONG WITH THE TROUGH. THIS WILL BRING CHANCES FOR THUNDERSTORMS
BACK TO THE AREA FROM SATURDAY NIGHT THROUGH SUNDAY NIGHT.
COLDER THAN NORMAL TEMPERATURES CAN BE EXPECTED THURSDAY BEFORE
FLOW ALOFT FLATTENS AND WARMER THAN NORMAL CONDITIONS RETURN FOR
FRIDAY AND SATURDAY. CLOUDS AND RAIN WILL KEEP HIGHS CLOSER TO
NORMAL ON SUNDAY. EXPECT COLDER THAN NORMAL TEMPERATURES ON MONDAY
BEHIND THE COLD FRONT.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1217 PM CDT TUE AUG 18 2015
FRONT CONTINUES TO LINGER SOUTH OF A WAUTOMA TO OSHKOSH TO
MANITOWOC LINE. THIS AREA WILL BE THE FOCUS FOR SCATTERED
THUNDERSTORM ACTIVITY THIS AFTERNOON AS TEMPERATURES WERE
NOW WARMING INTO THE MIDDLE TO UPPER 70S ALONG AND JUST SOUTH
OF THE FRONT. HAVE ADDED THUNDERSTORMS IN THE 18Z TAFS AT
KGRB/KATW. WILL MAKE A LAST MINUTE DECISION ON ADDING THEM TO
KMTW. OTHERWISE...IFR/MVFR CIGS CONTINUE ACROSS MUCH OF CENTRAL
INTO PORTIONS OF NORTH-CENTRAL AND FAR NORTHEAST WISCONSIN EARLY
THIS AFTERNOON. VFR CONDITIONS ALSO NOTED FROM KRHI NORTH INTO
VILAS COUNTY. SOME IMPROVEMENT SHOULD BE SEEN THIS AFTERNOON WHERE
THE IFR/MVFR CONDITIONS EXIST. FOR TONIGHT...A SIGNIFICANT ROUND
OF RAIN AND THUNDERSTORMS IS EXPECTED WITH UNUSUALLY STRONG SYSTEM
MOVES INTO THE UPPER MIDWEST/WESTERN GREAT LAKES REGION ON WEDNESDAY.
ONE THE MAIN ROUND OF RAIN MOVES OUT LATER TONIGHT...THERE IS SOME
POTENTIAL FOR A LINE OF SHOWERS TO REDEVELOP...MAINLY FROM 13Z TO
17Z AS THE LINE OF SHOWERS WILL RACE NORTHEAST. THIS LINE OF
SHOWERS COULD POSSIBLY PRODUCE STRONG GUSTY WINDS TO AROUND 40
KNOTS.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......MG
AVIATION.......ECKBERG
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
625 AM CDT TUE AUG 18 2015
UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND WEDNESDAY
ISSUED AT 316 AM CDT TUE AUG 18 2015
THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A COLD
FRONT STRETCHING ACROSS SOUTHWEST TO EAST-CENTRAL WISCONSIN EARLY
THIS MORNING. A SECONDARY FRONT RUNS ACROSS SOUTHERN MINNESOTA TO
EASTERN LAKE SUPERIOR. WEAK FGEN COMBINED WITH LINGERING ELEVATED
INSTABILITY CONTINUE TO GENERATE SCATTERED SHOWERS ALONG BOTH
FRONTS. BETTER MOISTURE AND INSTABILITY RESIDES OVER IOWA AND THE
PLAINS WHERE THUNDERSTORMS ARE OCCURRING. LOOKING FURTHER
UPSTREAM...LOW PRESSURE IS DEVELOPING OVER NORTHEAST COLORADO AHEAD
OF A DIGGING SHORTWAVE TROUGH. PRECIP TRENDS ALONG THE FRONT AND
ASSOCIATED WITH THE SURFACE LOW ARE THE MAIN FORECAST CONCERNS.
MODELS HAVE SLOWED DOWN THE PROGRESSION OF SURFACE FEATURES
SOMEWHAT. THE GFS IS A CLEAR OUTLIER...PROBABLY DUE TO ITS RATHER
POOR INITIALIZATION. PREFER A BLEND OF THE NAM/ECMWF/GEM.
TODAY...AS LOW PRESSURE CONSOLIDATES OVER THE CENTRAL PLAINS...THE
PRIMARY COLD FRONT IS PROJECTED TO STALL OVER CENTRAL AND EAST-
CENTRAL WISCONSIN...NEAR OR JUST SOUTH OF THE SOUTHERN FORECAST AREA
BORDER. WILL PROBABLY SEE AN UPTICK OF SHOWER ACTIVITY THIS MORNING
WITH WEAK SHORTWAVES MOVING OVERHEAD. ONCE THESE SHORTWAVES PASS TO
THE EAST BY LATE MORNING...NORTHERN WISCONSIN MAY SEE A DRY PERIOD
SO REDUCED PRECIP CHANCES THERE. SCATTERED SHOWERS WILL STILL IMPACT
THE SOUTH...CLOSER TO THE STALLED FRONT. WILL LIKELY SEE SHOWERS AND
A FEW STORMS BECOME MORE WIDESPREAD OVER CENTRAL WISCONSIN LATE IN
THE AFTERNOON AS MID-LEVEL FLOW STRENGTHENS OVER THE BOUNDARY.
HIGHS RANGING FROM THE MID 60S NORTH TO MID 70S SOUTH.
TONIGHT...A STRONG AREA OF LOW PRESSURE WILL LIFT NORTHEAST TOWARDS
MINNEAPOLIS WHILE PUSHING A COLD FRONT INTO SOUTHWEST OR CENTRAL
WISCONSIN BY 12Z WED. AS LARGE-SCALE ASCENT INCREASES...SHOULD SEE
AREAS OF SHOWERS AND THUNDERSTORMS LIFT NORTHEAST ACROSS THE
FORECAST AREA. THE MOST POTENT SWATH OF STORMS SHOULD ARRIVE LATE
IN THE NIGHT AHEAD OF THE COLD FRONT AND CLOSED MID-LEVEL
CIRCULATION. THOUGH INSTABILITY WILL BE QUITE LOW...PWATS WILL BE
GREATER THAN 1.5 INCHES AND FORCING WILL BE EXCELLENT. WIND FIELDS
ALOFT WILL ALSO BE STRENGTHENING AS 850MB WINDS APPROACH 40-45 KTS.
THOUGH CONVECTION WILL LIKELY BE LOW TOPPED...ANY CONVECTION WILL BE
CAPABLE OF BRINGING DOWN THESE STRONGER WINDS. THEREFORE...A
MARGINAL RISK LOOKS REASONABLE FOR THE SOUTHWEST FORECAST AREA.
TEMPS WILL NOT FALL MUCH TONIGHT. LOWS AROUND 60 NORTH TO THE MID
60S SOUTH.
WEDNESDAY...LOW PRESSURE WILL SLOWLY MOVE NORTHEAST OVER FAR
NORTHWEST WISCONSIN AS THE COLD FRONT SWEEPS ACROSS NORTH-CENTRAL
AND NORTHEAST WISCONSIN. SHOWERS AND STORMS ARE A DECENT BET AHEAD
OF THE FRONT DURING THE MORNING...AND THE THREAT OF STRONG GUSTY
WINDS WILL ACCOMPANY ANY STORMS. THE FRONT WILL EXIT NORTHEAST
WISCONSIN BY MID TO LATE AFTERNOON ENDING ANY STORM THREAT. WRAP
AROUND LIGHT SHOWERS MAY SPREAD INTO NORTH-CENTRAL WISCONSIN BY
EARLY EVENING. HIGHS RANGING FROM THE MID 60S WEST TO MID 70S EAST.
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY
ISSUED AT 316 AM CDT TUE AUG 18 2015
THE STRONG COLD FRONT AND UPPER LEVEL CYCLONE...THAT WILL IMPACT
THE AREA IN THE SHORT TERM...WILL DEPART THE REGION ON THEIR WAY
TOWARD HUDSON BAY DURING THE LATTER HALF OF THE WEEK. THE CHANCE
FOR RAIN WILL DECREASE AS THESE FEATURES DEPART...ENDING BY 00Z
FRIDAY. UPPER FLOW ACROSS THE REGION BRIEFLY BECOMES ZONAL...THEN
SOUTHWEST AS A WEST COAST TROUGH TRAVERSES THE CONUS. ANOTHER
COLD FRONT IS FORECAST TO MOVE ACROSS THE REGION OVER THE WEEKEND
ALONG WITH THE TROUGH. THIS WILL BRING CHANCES FOR THUNDERSTORMS
BACK TO THE AREA FROM SATURDAY NIGHT THROUGH SUNDAY NIGHT.
COLDER THAN NORMAL TEMPERATURES CAN BE EXPECTED THURSDAY BEFORE
FLOW ALOFT FLATTENS AND WARMER THAN NORMAL CONDITIONS RETURN FOR
FRIDAY AND SATURDAY. CLOUDS AND RAIN WILL KEEP HIGHS CLOSER TO
NORMAL ON SUNDAY. EXPECT COLDER THAN NORMAL TEMPERATURES ON MONDAY
BEHIND THE COLD FRONT.
&&
.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 625 AM CDT TUE AUG 18 2015
SCATTERED SHOWERS AND WIDESPREAD IFR CIGS WILL CONTINUE
NORTH OF A COLD FRONT OVER CENTRAL AND NORTHEAST WISCONSIN THROUGH
THE MORNING BEFORE CIGS RISE TO MVFR THIS AFTERNOON. SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS WILL BE POSSIBLE THIS
AFTERNOON...AND CONDITIONS COULD FALL TO IFR IN THE HEAVIER
SHOWERS/STORMS. WIDESPREAD SHOWERS AND THUNDERSTORMS AND LOWERING
CIGS/VSBYS WILL OCCUR TONIGHT WHEN A LOW PRESSURE SYSTEM APPROACHES
THE UPPER MISSISSIPPI VALLEY. LIFR CIGS WILL BE LIKELY OVER N-C
WISCONSIN LATE TONIGHT.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......MG
AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
608 AM CDT TUE AUG 18 2015
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 401 AM CDT TUE AUG 18 2015
MAIN FORECAST CONCERNS TODAY ARE ON THE POTENTIAL FOR A FEW
STRONG STORMS THIS AFTERNOON AND EVENING ALONG WITH WIDESPREAD
RAINFALL.
LATEST WATER VAPOR SHOWED A VIGOROUS SHORTWAVE MOVING INTO
WESTERN SOUTH DAKOTA/NEBRASKA. MEANWHILE...SURFACE LOW PRESSURE
WAS STARTING TO DEEPEN ACROSS SOUTHERN NEBRASKA/NORTHERN KANSAS.
THE WAVE WILL CONTINUE TO DIG SOUTHEAST TODAY AND INTENSIFY AS IT
MAKES EASTWARD PROGRESS. THE SURFACE LOW IS EXPECTED TO LIFT
NORTHEAST AND CONTINUE TO DEEPEN AS IT PUSHES INTO NORTHWEST
IOWA/SOUTHWEST MINNESOTA THIS AFTERNOON AND EVENING AS IT FEEDS
ON A BAROCLINIC ZONE SITUATED SOUTHWEST TO NORTHEAST ACROSS THE
UPPER MISSISSIPPI RIVER VALLEY. A WARM FRONT WILL BE LIFTED
NORTHWARD ACROSS THE FORECAST AREA THIS AFTERNOON INTO THIS
EVENING AS THE LOW CONTINUES TO TRACK NORTHEAST. WIDESPREAD
SHOWERS AND THUNDERSTORMS WILL OVERSPREAD SOUTHEAST MINNESOTA AND
NORTHEAST IOWA THIS AFTERNOON AND ARE EXPECTED TO TRACK NORTHEAST
THROUGH AFTERNOON INTO THE EVENING HOURS THROUGH WESTERN INTO
CENTRAL WISCONSIN. RATHER IMPRESSIVE SHEAR PROFILES NOTED FOR THIS
AFTERNOON AND EVENING WITH 0-3 KM BULK SHEAR VALUES OF OF 25 TO 40
KTS. LOOKING AT FORECAST SOUNDINGS/HODOGRAPHS...SUFFICIENT SHEAR
NOTED IN THE 0-1 KM LAYER TO WARRANT A POSSIBLE ISOLATED TORNADO
THREAT WITH THE POSSIBILITY OF SEEING A FEW MINI
SUPERCELLS....ESPECIALLY CLOSER TO THE TRIPLE POINT THIS AFTERNOON
INTO EARLY THIS EVENING. THE MAJOR LIMITING FACTOR FOR THIS IS THE
LACK OF SURFACE BASED CAPE. NAM FORECAST SOUNDINGS SHOW ONLY
AROUND 300 J/KG WHICH IS ON THE LOWER END FOR A MINI SUPERCELL
ENVIRONMENT. WITH STRONG 0-1 KM AGL HELICITY OF 350 TO 400...WILL
HAVE TO KEEP A VERY CLOSE EYE ON ANY OF THE STRONGER CELLS TODAY.
THE ONGOING SHOWERS AND STORMS THIS MORNING INTO THIS AFTERNOON IN
AND AHEAD OF THE WARM SECTOR SHOULD LIMIT SURFACE BASED CAPE AND
THE OVERALL SEVERE WEATHER THREAT. THE MAIN THREAT FROM THE STORMS
LOOKS TO BE BRIEF HEAVY RAINFALL AND POSSIBLY SOME GUSTY WINDS OUT
OF ANY STRONGER CELLS.
THE LOW IS EXPECTED TO LIFT ACROSS EAST CENTRAL MINNESOTA AND INTO
NORTHWEST WISCONSIN LATE TONIGHT INTO EARLY WEDNESDAY MORNING
WITH A DRY SLOT PUSHING ACROSS THE FORECAST AREA. THE BULK OF THE
SHOWERS AND STORMS WILL LIFT NORTH OF THE FORECAST AREA.
DEFORMATION RAIN WILL PERSIST ACROSS NORTHERN AND WESTERN
MINNESOTA WEDNESDAY MORNING....THEN LOOKS TO WRAP INTO LATE
WEDNESDAY MORNING INTO WEDNESDAY AFTERNOON. THIS WILL BRING RAIN
SHOWERS TO AREAS MAINLY ALONG AND NORTH OF INTERSTATE 90.
WRAPAROUND RAIN SHOWERS WILL GRADUALLY TAPER OFF AND LIFT NORTH OF
THE FORECAST AREA WEDNESDAY NIGHT. THE BIG STORY FOR WEDNESDAY WILL
BE MUCH COOLER AIR MOVING INTO THE REGION WITH HIGH TEMPERATURES
STRUGGLING TO REACH THE LOWER TO MIDDLE 60S. WEDNESDAY WILL FEEL
MORE LIKE EARLY FALL WITH BREEZY WEST WINDS AND WELL BELOW NORMAL
HIGH TEMPERATURES.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 401 AM CDT TUE AUG 18 2015
DRY AND BREEZY CONDITIONS ARE EXPECTED ACROSS THE UPPER MISSISSIPPI
RIVER VALLEY ON THURSDAY AS FLOW ALOFT SWITCHES BACK TO ZONAL. IT
WILL BE A RATHER COMFORTABLE DAY WITH HIGHS IN THE LOWER TO
MIDDLE 70S. TEMPERATURES RETURN TO NORMAL LATE AUGUST VALUES ON
FRIDAY WHEN HIGHS REBOUND INTO THE UPPER 70S TO LOWER 80S. BREEZY
SOUTH WINDS ARE EXPECTED ACROSS THE REGION ON FRIDAY WITH A TIGHT
PRESSURE GRADIENT SETTING UP AS LOW PRESSURE DEVELOPS OVER THE
NORTHERN PLAINS. A TROUGH AND COLD FRONT PUSH EAST ACROSS THE
DAKOTAS LATE FRIDAY INTO SATURDAY. SATURDAY LOOKS TO BE ANOTHER
BREEZY DAY AHEAD OF THE APPROACHING COLD FRONT WITH SOUTH WINDS OF
15 TO 20 MPH. THE COLD FRONT IS EXPECTED TO MOVE THROUGH LATE
SATURDAY AFTERNOON INTO SATURDAY NIGHT BRINGING A GOOD CHANCE OF
SHOWERS AND STORMS TO THE REGION. ITS A LITTLE TOO EARLY TO
DETERMINE IF THERE WOULD BE A SEVERE WEATHER THREAT FOR SATURDAY
EVENING. THE FRONT AND TROUGH SHOULD PUSH EAST OF THE FORECAST
AREA BY LATE SUNDAY MORNING BUT CYCLONIC FLOW ACROSS THE REGION
COULD PRODUCE A FEW RAIN SHOWERS ACROSS THE FORECAST
AREA...ESPECIALLY ACROSS NORTHERN WISCONSIN. HIGH TEMPERATURES ARE
EXPECTED TO COOL BACK INTO THE UPPER 60S TO LOWER 70S IN THE
WAKE OF THE FRONT SUNDAY. HIGH PRESSURE LOOKS TO RETURN BY
MONDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 608 AM CDT TUE AUG 18 2015
LEADING AREA OF SHOWERS ADVANCING EAST ACROSS THE REGION THIS
MORNING. FOR THE MOST PART...THESE ARE OCCURRING WITH VFR
CONDITIONS...BUT UNDER THE HEAVIER ACTIVITY IT QUICKLY GOES DOWN
TO IFR. THE 18.09Z HRRR SEEMS TO HAVE A GOOD HANDLE ON THESE
LEADING SHOWERS AND EXPECT THEM TO REMAIN OVER THE AREA THROUGH
THE MIDDLE OF THE MORNING BEFORE WEAKENING AS THE MAIN FORCING
SHIFTS BACK TO THE WEST AHEAD OF THE MAIN SHORT WAVE TROUGH. THE
MAJORITY OF THE HI-RES MODELS SUGGEST THE MAIN LINE OF CONVECTION
WILL COME IN DURING THE MIDDLE OF THE AFTERNOON BUT THE 18.00Z HI-
RES ARW IS A TOUCH FASTER SO WILL HONOR THIS FASTER TIMING WITH A
VCTS FOR BOTH SITES AND THEN GO CATEGORICAL THUNDERSTORMS FOR THE
LATE AFTERNOON INTO THE EARLY EVENING WITH MVFR/IFR CONDITIONS.
THE DRY SLOT SHOULD THEN WORK OVER THE AREA AND PUSH MOST OF THE
RAIN TO THE NORTH BY THE MIDDLE/LATE EVENING HOURS. NOT SURE WHAT
THE CEILINGS WILL DO IN THE DRY SLOT BUT PLAN TO STAY PESSIMISTIC
AND KEEP THEM DOWN IN THE IFR RANGE. WILL ALSO HOLD ONTO A VCSH AS
SOME OF THE MESO MODELS SHOW SOME SHOWERS OCCASIONALLY COMING
THROUGH UNTIL WELL INTO THE OVERNIGHT HOURS.
&&
.HYDROLOGY...THROUGH WEDNESDAY
ISSUED AT 401 AM CDT TUE AUG 18 2015
WIDESPREAD RAINFALL AMOUNTS OF 1 TO 1.3 INCHES ARE EXPECTED FROM
TODAY THROUGH TONIGHT. BRIEF HEAVY RAINFALL IS POSSIBLE AT TIMES
BUT GIVEN 1 HOUR FLASH FLOOD GUIDANCE RANGING FROM 1.5 TO 2.7
INCHES ALONG WITH ANTECEDENT CONDITIONS...NOT ANTICIPATING THE
NEED FOR ANY HYDROLOGIC HEADLINES.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04
HYDROLOGY...WETENKAMP
FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND WEDNESDAY
ISSUED AT 316 AM CDT TUE AUG 18 2015
THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A COLD
FRONT STRETCHING ACROSS SOUTHWEST TO EAST-CENTRAL WISCONSIN EARLY
THIS MORNING. A SECONDARY FRONT RUNS ACROSS SOUTHERN MINNESOTA TO
EASTERN LAKE SUPERIOR. WEAK FGEN COMBINED WITH LINGERING ELEVATED
INSTABILITY CONTINUE TO GENERATE SCATTERED SHOWERS ALONG BOTH
FRONTS. BETTER MOISTURE AND INSTABILITY RESIDES OVER IOWA AND THE
PLAINS WHERE THUNDERSTORMS ARE OCCURRING. LOOKING FURTHER
UPSTREAM...LOW PRESSURE IS DEVELOPING OVER NORTHEAST COLORADO AHEAD
OF A DIGGING SHORTWAVE TROUGH. PRECIP TRENDS ALONG THE FRONT AND
ASSOCIATED WITH THE SURFACE LOW ARE THE MAIN FORECAST CONCERNS.
MODELS HAVE SLOWED DOWN THE PROGRESSION OF SURFACE FEATURES
SOMEWHAT. THE GFS IS A CLEAR OUTLIER...PROBABLY DUE TO ITS RATHER
POOR INITIALIZATION. PREFER A BLEND OF THE NAM/ECMWF/GEM.
TODAY...AS LOW PRESSURE CONSOLIDATES OVER THE CENTRAL PLAINS...THE
PRIMARY COLD FRONT IS PROJECTED TO STALL OVER CENTRAL AND EAST-
CENTRAL WISCONSIN...NEAR OR JUST SOUTH OF THE SOUTHERN FORECAST AREA
BORDER. WILL PROBABLY SEE AN UPTICK OF SHOWER ACTIVITY THIS MORNING
WITH WEAK SHORTWAVES MOVING OVERHEAD. ONCE THESE SHORTWAVES PASS TO
THE EAST BY LATE MORNING...NORTHERN WISCONSIN MAY SEE A DRY PERIOD
SO REDUCED PRECIP CHANCES THERE. SCATTERED SHOWERS WILL STILL IMPACT
THE SOUTH...CLOSER TO THE STALLED FRONT. WILL LIKELY SEE SHOWERS AND
A FEW STORMS BECOME MORE WIDESPREAD OVER CENTRAL WISCONSIN LATE IN
THE AFTERNOON AS MID-LEVEL FLOW STRENGTHENS OVER THE BOUNDARY.
HIGHS RANGING FROM THE MID 60S NORTH TO MID 70S SOUTH.
TONIGHT...A STRONG AREA OF LOW PRESSURE WILL LIFT NORTHEAST TOWARDS
MINNEAPOLIS WHILE PUSHING A COLD FRONT INTO SOUTHWEST OR CENTRAL
WISCONSIN BY 12Z WED. AS LARGE-SCALE ASCENT INCREASES...SHOULD SEE
AREAS OF SHOWERS AND THUNDERSTORMS LIFT NORTHEAST ACROSS THE
FORECAST AREA. THE MOST POTENT SWATH OF STORMS SHOULD ARRIVE LATE
IN THE NIGHT AHEAD OF THE COLD FRONT AND CLOSED MID-LEVEL
CIRCULATION. THOUGH INSTABILITY WILL BE QUITE LOW...PWATS WILL BE
GREATER THAN 1.5 INCHES AND FORCING WILL BE EXCELLENT. WIND FIELDS
ALOFT WILL ALSO BE STRENGTHENING AS 850MB WINDS APPROACH 40-45 KTS.
THOUGH CONVECTION WILL LIKELY BE LOW TOPPED...ANY CONVECTION WILL BE
CAPABLE OF BRINGING DOWN THESE STRONGER WINDS. THEREFORE...A
MARGINAL RISK LOOKS REASONABLE FOR THE SOUTHWEST FORECAST AREA.
TEMPS WILL NOT FALL MUCH TONIGHT. LOWS AROUND 60 NORTH TO THE MID
60S SOUTH.
WEDNESDAY...LOW PRESSURE WILL SLOWLY MOVE NORTHEAST OVER FAR
NORTHWEST WISCONSIN AS THE COLD FRONT SWEEPS ACROSS NORTH-CENTRAL
AND NORTHEAST WISCONSIN. SHOWERS AND STORMS ARE A DECENT BET AHEAD
OF THE FRONT DURING THE MORNING...AND THE THREAT OF STRONG GUSTY
WINDS WILL ACCOMPANY ANY STORMS. THE FRONT WILL EXIT NORTHEAST
WISCONSIN BY MID TO LATE AFTERNOON ENDING ANY STORM THREAT. WRAP
AROUND LIGHT SHOWERS MAY SPREAD INTO NORTH-CENTRAL WISCONSIN BY
EARLY EVENING. HIGHS RANGING FROM THE MID 60S WEST TO MID 70S EAST.
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY
ISSUED AT 316 AM CDT TUE AUG 18 2015
THE STRONG COLD FRONT AND UPPER LEVEL CYCLONE...THAT WILL IMPACT
THE AREA IN THE SHORT TERM...WILL DEPART THE REGION ON THEIR WAY
TOWARD HUDSON BAY DURING THE LATTER HALF OF THE WEEK. THE CHANCE
FOR RAIN WILL DECREASE AS THESE FEATURES DEPART...ENDING BY 00Z
FRIDAY. UPPER FLOW ACROSS THE REGION BRIEFLY BECOMES ZONAL...THEN
SOUTHWEST AS A WEST COAST TROUGH TRAVERSES THE CONUS. ANOTHER
COLD FRONT IS FORECAST TO MOVE ACROSS THE REGION OVER THE WEEKEND
ALONG WITH THE TROUGH. THIS WILL BRING CHANCES FOR THUNDERSTORMS
BACK TO THE AREA FROM SATURDAY NIGHT THROUGH SUNDAY NIGHT.
COLDER THAN NORMAL TEMPERATURES CAN BE EXPECTED THURSDAY BEFORE
FLOW ALOFT FLATTENS AND WARMER THAN NORMAL CONDITIONS RETURN FOR
FRIDAY AND SATURDAY. CLOUDS AND RAIN WILL KEEP HIGHS CLOSER TO
NORMAL ON SUNDAY. EXPECT COLDER THAN NORMAL TEMPERATURES ON MONDAY
BEHIND THE COLD FRONT.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1037 PM CDT MON AUG 17 2015
LIGHT RAIN SHOWERS AND DRIZZLE WITH MVFR CONDITIONS ARE EXPECTED
OVERNIGHT AS A MID LEVEL SHORTWAVE TRACKS THROUGH THE WESTERN
GREAT LAKES. SOME IFR CONDITIONS ARE ALSO POSSIBLE AT TIMES WITH
HEAVIER SHOWERS. GIVEN THE EXPANSIVE CLOUD COVER WIDESPREAD FOG IS
NOT ANCITIPATED WITH THIS SET OF TAFS OVERNIGHT. A WARM FRONT
WILL LIFT NORTH ON TUESDAY...BRINGING MORE SHOWERS AND
THUNDERSTORMS TO THE AREA. A BETTER CHANCE FOR SHOWERS AND
THUNDERSTORMS WILL OCCUR TUESDAY EVENING WHEN A LOW PRESSURE
SYSTEM APPROACHES THE UPPER MISSISSIPPI VALLEY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......MG
AVIATION.......KURIMSKI
AREA FORECAST DISCUSSION
NWS JACKSON KY
315 AM EDT THU AUG 20 2015
.UPDATE...
ISSUED AT 315 AM EDT THU AUG 20 2015
UPDATED FOR PRECIP TRENDS. AN AREA OF SHOWERS IS SLOWLY MAKING
PROGRESS TOWARD THE AREA FROM THE WEST AND WILL BRING MANY
LOCATIONS PRECIP OVERNIGHT. PRECIP WILL CUT OFF FROM WEST TO EAST
ON THURSDAY. BASED ON 00Z MODELS...HAVE TRIMMED DOWN POPS A BIT
FASTER ON THURSDAY.
UPDATE ISSUED AT 1055 PM EDT WED AUG 19 2015
CONVECTION HAS FILLED IN ACROSS EASTERN TENNESSEE AND PORTIONS OF
SOUTHEAST KENTUCKY OVER THE PAST HOUR. HAVE INCREASED POPS TO
ACCOUNT FOR THIS ACTIVITY. MORE DEVELOPMENT IS ALSO OCCURRING BACK
ACROSS WESTERN KENTUCKY OUT AHEAD OF THE APPROACHING COLD FRONT.
HAVE MADE SOME MINOR ADJUSTMENTS IN THE POPS THROUGH THE REST OF
THE NIGHT...BASED ON THE LATEST RADAR AND HIGHER RESOLUTION MODEL
TRENDS. THIS WILL KEEP MAINLY LIKELY POPS ACROSS THE AREA THROUGH
DAWN AS THE FRONT APPROACHES FROM THE WEST AND NORTHWEST.
UPDATE ISSUED AT 819 PM EDT WED AUG 19 2015
FRESHENED UP THE HOURLY POPS ACCORDING TO THE LATEST RADAR TRENDS.
A CLUSTER OF SHOWERS AND STORMS IS CURRENTLY ALIGNED NEAR THE I-75
CORRIDOR...WITH MORE WIDESPREAD CONVECTION DOWN IN TENNESSEE. THE
LATEST HRRR YIELDS A GENERAL WEAKENING TREND THROUGH EARLY THIS
EVENING...WITH OUR SOUTHWEST SEEING THE BEST AREAL COVERAGE
THROUGH THIS EVENING. HAVE USED A BLEND OF THE HRRR AND GENERAL
EXTRAPOLATION FROM THE MOSAIC RADAR FOR THE POPS OVER THE NEXT
SEVERAL HOURS...BEFORE BLENDING INTO THE INHERITED FORECAST.
UPDATES HAVE BEEN SENT.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 311 PM EDT WED AUG 19 2015
AREA OF LOW PRESSURE CONTINUES TO PUSH NORTHEAST ACROSS THE
NORTHERN GREAT LAKES...WITH A TRAILING COLD FRONT STRETCHING BACK
SOUTH ACROSS ILLINOIS AND MISSOURI THIS AFTERNOON. THIS FRONT WILL
BE THE FOCUS FOR OUR WEATHER OVER THE NEXT 18 TO 24 HOURS AS IT
CONTINUES TO PUSH EAST. PLENTY OF MOISTURE CONTINUES TO REMAIN
AHEAD OF THE ADVANCING FRONT...LEADING TO SCATTERED TO NUMEROUS
SHOWERS AND STORMS ACROSS MUCH OF THE OHIO RIVER VALLEY. ORGANIZED
AREA OF SHOWERS AND STORMS HAS JUST ABOUT CLEARED OUR NORTHEAST
COUNTIES...WITH A LULL SPREADING OVER THE AREA.
HOWEVER...ADDITIONAL ISOLATED SHOWERS AND A FEW STORMS ARE
STARTING OT POP UP IN SOUTH CENTRAL KENTUCKY. THIS ACTIVITY WILL
CONTINUE TO FILL IN AND DEVELOPMENT THROUGH THE EVENING.
HOWEVER...AS INSTABILITY DECREASES WITH SUNSET THIS EVENING...WE
COULD SEE MUCH OF THE ACTIVITY OUT THERE NOW DIE OFF EXCEPT FOR
THE MORE ORGANIZED CLUSTERS OF STORMS. FOR EASTERN
KENTUCKY...THERE DOESN`T APPEAR TO BE ANY ADDITIONAL ORGANIZED
STORMS HEADING OUR WAY...SO IT LOOKS LIKE WE SHOULD SEE A LULL
INTO THE OVERNIGHT HOURS. HOWEVER...COLD FRONT WILL MOVE LATE
TONIGHT AND AROUND DAYBREAK...WITH SHOWERS AND STORMS INCREASING
IN COVERAGE. THIS FRONT WILL CROSS THE AREA TOMORROW
MORNING...BEFORE EXITING BY THURSDAY AFTERNOON. SEVERE THREAT
SHOULD REMAIN LOW GIVEN THE FRONT COMING THROUGH DURING THE
MORNING HOURS WITH LACK OF STRONGER SURFACE INSTABILITY. AS THE
FRONT EXITS BY MID AFTERNOON ON THURSDAY...PRECIPITATION THREAT
WILL END. COOLER AND LESS HUMID CONDITIONS WILL SPREAD IN BEHIND
THE FRONT...SETTING THE STAGE FOR A MUCH COOLER NIGHT FOR THURSDAY
NIGHT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 311 PM EDT WED AUG 19 2015
THE WEATHER STARTS OUT FAIRLY BENIGN EARLY FRIDAY MORNING AS A SFC
HIGH PRESSURE BUILDS INTO THE REGION BEHIND A COLD FRONTAL PASSAGE.
THIS WILL ALLOW FOR COOLER...DRIER AIR TO FILTER INTO THE REGION
KEEPING CLOUDS TO A MINIMUM AND DEW POINTS IN THE 50S TO LOWER 60S.
IN FACT...FRIDAY WILL BE A BEAUTIFUL SUMMER DAY WITH HIGHS IN THE
MID TO UPPER 70S AND LOW HUMIDITY.
BY SUNDAY...AN UPPER LEVEL LOW DEVELOPS ALONG THE CANADIAN/US BORDER
MOVING MAINLY EWD. AN ASSOCIATED SFC LOW DEVELOPS PULLING A COLD
FRONT TO ITS SOUTH ACROSS THE CENTRAL U.S. ON MONDAY.
HOWEVER...THESE FEATURES SHOULD STAY WELL TO OUR NORTH AND LIMIT THE
FORCING...AND THE PRECIP...AS THE FRONT MOVES THROUGH EASTERN KY ON
MONDAY.
HIGH PRESSURE WILL BUILD INTO THE REGION ONCE AGAIN AFTER THE
FRONTAL PASSAGE ON MONDAY...ALLOWING FOR COOLER AND DRIER WEATHER TO
END THE PERIOD. TEMPERATURES THROUGHOUT THE EXTENDED WILL BE AT OR
BELOW NORMAL VALUES WITH HIGHS GENERALLY IN THE UPPER 70S AND LOW
80S...AND LOWS IN THE 50S TO LOW 60S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 315 AM EDT THU AUG 20 2015
CONDITIONS WERE LARGELY VFR AT THE START OF THE PERIOD...WITH MVFR
AT A FEW PLACES. THERE WERE A FEW LIGHT SHOWERS...WITH A GREATER
CONCENTRATION ABOUT TO MOVE IN FROM THE WEST. THESE SHOWERS WERE
AHEAD OF A COLD FRONT WHICH WILL MOVE THROUGH ON THURSDAY MORNING.
A DROP TO MVFR AND LOCALIZED IFR IS EXPECTED OVERNIGHT AS SHOWERS
DEVELOP AND MOVE IN. DRY WEATHER AND VFR SHOULD RETURN FROM NW TO
SE DURING THE COURSE OF THE DAY.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...HAL
SHORT TERM...KAS
LONG TERM...JVM
AVIATION...HAL
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1226 AM CDT THU AUG 20 2015
.SHORT TERM...(This Evening through Friday Night)
Issued at 400 PM CDT WED AUG 19 2015
Can`t beat this weather...October in mid August. Better enjoy it
while it lasts.
Deep upper trough extending from MN through eastern KS into OK will
continue tracking east tonight. Water vapor imagery shows a weak
vorticity max dropping down the back side of the trough across
western IA. Widely scattered instability showers have popped as a
result. HRRR trend supports low-end slight chance PoPs over northern
MO until about sunset. Most likely only sprinkles. Otherwise,
heating based stratocu cloud cover from NE into the CWA should
dissipate with loss of daytime heating and leave skies cloud free by
midnight. Could be flirting with record lows tomorrow morning. MCI
record min is 53 and STJ is 48.
Temperatures will rebound, but remain below average on Thursday,
before returning closer to seasonal on Friday. Warming will be the
result of the cooler/drier air being pulled away as the upper trough
moves east vs return flow from a retreating surface high. But even
the warm-up will be pleasant by summer standards as dewpoints will
remain in the 50s on Thursday and only increase into the lower 60s
on Saturday. Sure beats the upper 60s to lower 70s which occur so
often this time of year.
Will leave the forecast rain-free through Friday except for a token
slight chance PoP over far northwest MO late Thursday night.
Rain chances begin to ramp up late Friday night into Saturday
morning as stronger isentropic ascent tied to increasing low-level
moisture and development of the nocturnal low-level jet.
.LONG TERM...(Saturday through Wednesday)
Issued at 400 PM CDT WED AUG 19 2015
The GFS, European, and Canadian models are all in good agreement
that this weekend will see a pattern very similar to the pattern
that moved through the area the past couple days. The models depict
an upper level trough will develop and slide east over the northern
states through the weekend. An associated cold front will advance
across the Central Plains ahead of the trough. The models show the
best chance for storms will be Saturday night into Sunday as the
upper level trough moves over the Dakotas and the cold front moves
through the forecast area. Initially, convection will occur across
MN and IA earlier Saturday evening before spreading further south
into the forecast area as the cold front interacts with increasing
moisture ahead of and along the front. Severe potential would be
limited if showers or cloud cover linger throughout the day on
Saturday as these could restrict surface heating and convection
later in the evening. Just like today, showers could linger on
Sunday morning after the passage of the cold front. Also,
temperatures will be lower than normal for August on Sunday into
Monday, and dry conditions will prevail after the lingering showers
dissipate on Sunday. Temperatures gradually increase throughout the
early part of the work week as upper level high pressure slowly
builds over the Plains.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1225 AM CDT THU AUG 20 2015
VFR conditions are expected to dominate the terminals for the next
24 hours. Only issue there might be a bit of steam fog from the
Missouri River for the KSTJ terminal around sunrise. Otherwise,
expect winds to remain under 10 knots from the southwest.
&&
.CLIMATE...
Issued at 400 PM CDT WED AUG 19 2015
Record low temperature/date for August 19th...
Kansas City (MCI) 53/1950
St. Joseph (STJ) 48/1981
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...MJ
LONG TERM...HEC
AVIATION...Cutter
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1252 AM EDT THU AUG 20 2015
.SYNOPSIS...
UNSETTLED WEATHER WILL CONTINUE THROUGH THURSDAY. A WEAK COLD
FRONT WILL MOVE ACROSS THE AREA FRIDAY. LESS COVERAGE OF SHOWERS
AND THUNDERSTORMS CAN BE EXPECTED FRIDAY THROUGH EARLY NEXT WEEK
WITH TYPICAL LATE SUMMERTIME TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
AS OF 1000 PM THURSDAY...THE LARGE INLAND CONVECTIVE BLOBS CONTINUE
TO DECAY EARLY THIS MORNING...WHILE A VERY FEW SHOWERS HAVE RECENTLY
DEVELOPED ACROSS COASTAL NORTH CAROLINA. THIS IS ALL WELL-HANDLED IN
THE EVENING SHIFT`S FORECAST AND NO SIGNIFICANT CHANGES ARE NEEDED
WITH THIS EARLY-MORNING NEAR-TERM UPDATE. FORECAST LOWS WERE BUMPED
UP A DEGREE OR TWO BASED ON LATEST TEMPERATURES. DISCUSSION FROM
1000 PM FOLLOWS...
THE BRUNT OF A LARGE CONVECTIVE COMPLEX WAS PASSING BY TO OUR N WITH
THE SOUTHERN PORTION OF THIS AREA OF THUNDERSTORMS MOVING ACROSS A
PORTION OF THE FORECAST AREA... BASICALLY N OF A FLO TO CPC TO
BURGAW LINE. THE OVERALL INTENSITY OF RAINFALL CONTINUES TO DIMINISH
AND ALTHOUGH A BRIEF HEAVY DOWNPOUR IS POSSIBLE...OVERALL RAINFALL
RATES GOING FORWARD WILL NOT BE SIGNIFICANT HERE FOR THE REMAINDER
OF THE NIGHT.
ANOTHER MUCH SMALLER BATCH OF THUNDERSTORMS WAS ONGOING TO OUR SW
ACROSS SOUTHERN SOUTH CAROLINA. THE NORTHERN PERIPHERY OF THIS
AREA OF STORMS MAY SKIRT PORTIONS OF WILLIAMSBURG AND GEORGETOWN
COUNTIES...12-2 AM. A HEAVY DOWNPOUR IS POSSIBLE...BUT SEVERE
WEATHER IS NOT EXPECTED.
I AM INCLINED TO THINK THAT WE WILL GET SOME REDEVELOPMENT OF
CONVECTION OVER THE WARM OCEAN WATERS LATE TONIGHT AND EARLY THU
MORNING AS HAS BEEN THE CASE FOR THE LAST FEW NIGHTS. THE HIGH
RESOLUTION HRRR MODEL IS FINALLY BEGINNING TO SETTLE ON SUCH A
SOLUTION. IF THIS CONVECTION DOES INDEED MATERIALIZE...IT MAY
SKIRT PORTIONS OF THE COAST...MAINLY FROM THE GRAND STRAND THROUGH
CAPE FEAR EARLY IN THE MORNING.
GIVEN THE EXTENT AND MAGNITUDE OF THE RAINFALL TODAY AND TONIGHT...
WILL CONTINUE TO INCLUDE PATCHY LATE NIGHT FOG ACROSS PORTIONS OF
THE AREA.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...A MID LEVEL CYCLONE WILL MOVE ACROSS THE
GREAT LAKES WITH A BROAD ZONAL FLOW PUSHING A COLD FRONT ACROSS
THE AREA EARLY FRIDAY. BY THE END OF THE PERIOD MID LEVEL HIGH
PRESSURE BUILDS BACK IN FROM THE SOUTH WITH ANY APPRECIABLE
AFFECTS FROM THE FRONT BASICALLY GONE. FOR THURSDAY...WEAK SURFACE
TROUGHING WILL STILL RESIDE ACROSS THE AREA AND GOOD CHANCE POPS
REMAIN IN THE FORECAST. POPS DECREASE SOMEWHAT FOR FRIDAY AS THE
WEAK FRONT HAS A SIGNIFICANT SUBSIDENCE INVERSION IN THE 700-850MB
LAYER WHICH WILL MAKE CONVECTIVE DEVELOPMENT MORE CHALLENGING THAN
PREVIOUS DAYS. THERE REMAINS A VERY MOIST PROFILE HOWEVER AND
LOWER CHANCE POPS SHOULD BE A GOOD COMPROMISE. TEMPERATURES CHANGE
LITTLE THROUGH THE PERIOD WITH HIGHS IN THE 90S AND LOWS IN THE
70S.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 300 PM WEDNESDAY...COLD FRONT AND ITS ASSOCIATED MOISTURE
BOTH MOVING OFF THE COAST EARLY SATURDAY FOR A RAIN FREE WEEKEND
DESPITE SOME LAGGING UPPER LEVEL ENERGY PASSING THROUGH SUNDAY AND
SUNDAY NIGHT. MOISTURE RETURN WILL BEGIN GRADUALLY ON MONDAY AS A
PIEDMONT TROUGH DEVELOPS AND A MID LEVEL SHEAR LINE REMAINS ABOVE
THE AREA. COLD FRONT AND HEALTHY UPPER TROUGH DROP INTO THE AREA
TUESDAY AND WEDNESDAY AND LIKELY BRINGING SOME PRETTY UNSETTLED
WEATHER. OUR BEACHES MAY EVEN BEGIN SEEING SOME DANNY SWELLS EARLY
NEXT WEEK.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 06Z...SHOWERS CONTINUE EARLY THIS MORNING. HI RESOLUTION
MODELS SUGGEST RAIN DYING OFF AND ENDING SHORTLY...PERHAPS SHIFTING
OFFSHORE BY DAYBREAK. EXPECT BROKEN CLOUD COVER AT KFLO/KLBT TO
TEMPER ANY POTENTIAL FOG ...ALTHOUGH CANT TOTALLY RULE OUT BRIEF
MVFR VSBYS. SOME MID LEVEL LIFT SUGGESTS POTENTIAL ISOLATED SHOWERS
COULD CONTINUE. AT THE COASTAL TERMINALS DO NOT EXPECT ANY FOG
ISSUES THIS MORNING. SOME LIFT IN THE PRE-DAWN HOURS SUGGEST SHOWER
ACTIVITY AT KILM BECOMING MORE WIDESPREAD IN THE MID MORNING HOURS
ALL COASTAL TERMINALS WITH VCTS LIKELY. CONVECTION WORKS INLAND BY
AFTERNOON. WINDS WILL BE SW-W EARLY BECOMING SW BY MID-LATE MORNING.
EXTENDED OUTLOOK...VFR...WITH SCATTERED SHOWERS AND THUNDERSTORMS
THROUGH FRIDAY.
&&
.MARINE... NEAR TERM /THROUGH TONIGHT/...
AS OF 1245 AM THURSDAY...VIRTUALLY NO CHANGES WERE NEEDED TO THE
FORECAST WITH THIS EARLY-MORNING NEAR-TERM UPDATE. DISCUSSION FROM
1000 PM WEDNESDAY FOLLOWS...
SOUTHWEST WINDS WILL REMAIN ACROSS THE WATERS THROUGH THE NIGHT.
WIND SPEEDS WILL BE UP TO 15 KT. SEAS 2 TO 3 FT. A 8 TO 9 SECOND ESE
SWELL WILL REMAIN AND IN THE COMING DAYS THIS SWELL WILL ONLY
INCREASE IN STRENGTH. WE SHOULD AGAIN SEE CONVECTION DEVELOPING
ACROSS THE WATERS WITH THE APPROACH OF DAYBREAK THU.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...THE PIEDMONT TROUGH WILL BECOME MORE A
LITTLE BETTER DEFINED THURSDAY AND WIND FIELDS WILL SHOULD RESPOND
WITH A SOUTHWEST FLOW OF 10-15 KNOTS...MOSTLY IN THE LOWER END OF
THE RANGE. A WEAK FRONT WILL PUSH ACROSS THE WATERS EARLY FRIDAY
WITH THE FRONT AND THE LAND BREEZE PROVIDING A BRIEF OFFSHORE
FLOW. BY LATER IN THE DAY LIGHT AND VARIABLE WINDS DEVELOP UNDER A
WEAK PRESSURE PATTERN. AS FOR SEAS...GENERALLY 2-3 FEET THROUGH
THE PERIOD.
LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 PM WEDNESDAY...NORTHEAST WINDS ON SATURDAY AS COLD FRONT
SLOWLY MOVES OFF TO OUR SOUTH. WITH NO BIG PUSH OF HIGH PRESSURE
BEHIND THIS BOUNDARY WIND SPEEDS WILL REMAIN VERY LIGHT. NORTHEAST
OR EAST WINDS ON SUNDAY AS THE BOUNDARY DISSIPATES SOUTH OF THE
AREA. A MORE TYPICAL SOUTHWESTERLY WIND SHOULD RETURN ON MONDAY AS A
PIEDMONT TROUGH BEGINS TO DEVELOP.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...RJD/TRA
SHORT TERM...SHK
LONG TERM...MBB
AVIATION...MRR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
230 AM EDT THU AUG 20 2015
.SYNOPSIS...
A COLD FRONT WILL MOVE SLOWLY THROUGH THE REGION THURSDAY INTO
THURSDAY NIGHT. LOWER HUMIDITY AND MAINLY DRY WEATHER WILL RETURN
TO MOST OF CENTRAL PA FRIDAY THROUGH THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
SHOWER ACTIVITY IS FADING WITH THE LOSS OF HEATING AND INCREASED
STABILITY. THE HRRR CONTINUES WITH THE IDEA OF SCATTERED
ACTIVITY MEANDERING ABOUT FOR THE OVERNIGHT SO WHILE I LOWERED
POPS...I DID NOT ELIMINATE THE MENTION OF RAIN ALTOGETHER. IT DOES
LOOK LIKE MOST AREAS WILL REMAIN RAIN FREE FOR THE REST OF THE
NIGHT HOWEVER.
THE OVERNIGHT PERIOD WILL REMAIN WARM AND MUGGY WITH LOWS IN THE
UPPER 60S TO LOW 70S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
AN INCREASE IN CYCLONIC FLOW ALOFT AHEAD OF IMPRESSIVE MID LEVEL
CYCLONE FOR THIS TIME OF YEAR OVER THE UPPER GREAT LAKES REGION...
AND STRENGTHENING OF THE S-SE LLJ SHOULD RESULT IN AN INCREASE IN
SHOWER ACTIVITY ONCE AGAIN AFTER 12Z. A BLEND OF NEAR AND SHORT
TERM MODEL QPF TARGETS AN AXIS OF PCPN FROM THE SRN DELMARVA INTO
ERN PA WHICH MAY BE ENHANCED BY SSERLY FEED OF ATLANTIC
MOISTURE.
THE SFC COLD FRONT IS FORECASTED TO MOVE THROUGH THE CENTRAL
MOUNTAINS BY LATE AFTERNOON AND THE SUSQUEHANNA VALLEY THURSDAY
EVENING.
THE BEST SHEAR VALUES LOOK TO BE NORTH AND WEST OF THE SPINE OF
THE APPALACHIANS WITH THE SREF INDICATING A 70% PROBABILITY OF
SHEAR GREATER THAN 30 KTS IN THE NORTHWEST MOUNTAINS AND WESTERN
LAURELS LATE TOMORROW AFTERNOON. SURFACE CAPE VALUES WILL RANGE
FROM 1000 TO 2000 J/KG IN THE AFTERNOON.
THE BIGGEST CONCERN FOR THURSDAY IS THE THREAT FOR FLASH FLOODING
AS WE HAVE ANOMALOUSLY HIGH PWATS BETWEEN TWO AND THREE STANDARD
DEVIATIONS ABOVE NORMAL. RFC FFG MOSAIC INDICATES THAT AMTS ARE
HIGHEST /2 TO 4 INCHES OVER A 6-HOUR PERIOD/ WHERE WE EXPECT THE
HEAVIEST RAIN TO FALL - ACROSS THE ERN HALF OF THE CWA THURSDAY
AFTERNOON AND NIGHT.
MODEL/ENSEMBLE CONSENSUS QPF STILL POINTS TWD JUST UNDER ONE INCH
ACROSS THE WESTERN PART OF THE CWA...AND 1-1.5 INCHES ACROSS THE
EAST...WITH OBVIOUSLY SOME HIGHER NARROW-BANDED 2+ INCH TOTALS.
HIGH TEMPERATURES ON THURSDAY WILL REMAIN MILD RANGING FORM THE
MID 70S IN THE NORTHWEST MOUNTAINS TO THE LOW 80S ACROSS THE LOWER
SUSQUEHANNA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
HIGH PRESSURE WILL BE IN CONTROL ACROSS MOST OF THE AREA THIS
WEEKEND...AND PROVIDE GENERALLY FAIR WEATHER WITH SLIGHTLY BELOW
TO NEAR-AVERAGE TEMPS. THE NEXT COLD FRONT IS FCST TO ARRIVE ON
MONDAY BEFORE ANOTHER PUSH OF COOLER AND DRIER AIR FOR TUESDAY.
THE DAY2-3 FRONTAL BOUNDARY WILL LINGER OFF THE NORTHEAST/MID-
ATLC COAST THIS WEEKEND AND MAY TRY TO DRIFT WWD WITH TIME. MODEL
CONSENSUS HAS PUSHED N-S PCPN AXIS FARTHER OFF THE COAST AND
THEREFORE WILL ONLY KEEP SCHC POPS ACROSS THE FAR ERN ZONES ON
SUNDAY.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
MOIST SERLY FLOW COMBINING WITH COOLING OF BLYR TO PRODUCE
EXPANDING STRATUS ACROSS CENTRAL PA EARLY THIS AM. CLIMATOLOGY IN
THIS SCENARIO...AS WELL AS SREF OUTPUT...INDICATE LIKELY IFR CIGS
EARLY THIS MORNING AT THE HIGH TERRAIN AIRFIELDS OF KBFD AND KJST
AND PRIMARILY MVFR ELSEWHERE. HOWEVER...CAN/T RULE OUT A PERIOD OF
IFR CIGS AT KAOO/KUNV ARND 08Z-12Z.
PERSISTENT SERLY FLOW SHOULD KEEP THE STRATUS IN PLACE ACROSS
CENTRAL PA TODAY. HOWEVER...MDL SOUNDINGS SUPPORT SOME MODEST
IMPROVEMENT BY LATE AM TODAY...WITH MANY LOCATIONS REMAINING IN
THE MVFR CATEGORY AND KMDT/KLNS POSSIBLY BECOMING VFR. FOCUS FOR
THIS AFTN/EVENING WILL SHIFT TOWARD APPROACHING COLD FRONT...WHICH
WILL PRODUCE LOCALLY HEAVY SHRA/TSRA AS IT PUSHES EAST ACROSS THE
REGION. MOST LOCATIONS WILL LIKELY EXPERIENCE BRIEF IFR REDUCTIONS
AS THESE SHRA/TSRA PASS THRU...DESPITE MORE FAVORABLE PREDOMINANT
CONDS.
A RETURN TO VFR CONDS APPEARS LIKELY ACROSS THE WESTERN HALF OF PA
BY 00Z FRIDAY...AS A DRIER WEST FLOW ARRIVES IN WAKE OF FRONT.
HOWEVER...THE SLOW MOVING FRONT COULD CREATE LINGERING SHRA AND
POSSIBLE REDUCTIONS INTO THE EVENING OVER THE EASTERN HALF OF THE
STATE.
OUTLOOK...
FRI...AM FOG POSS KBFD.
SAT-MON...NO SIG WX EXPECTED.
&&
.HYDROLOGY...
AN ELEVATED RISK OF VERY LOCALIZED FLASH FLOODING WILL EXIST THURSDAY
INTO THURSDAY NIGHT...MAINLY ACROSS THE EASTERN HALF OF PENN.
NARROW...NORTH-SOUTH BANDS OF HEAVY TO LOCALLY EXCESSIVE RAINFALL
ARE POSSIBLE WHICH MAY RESULT IN SOME FLASH FLOODING AND SHARP
RISES ON SMALL STREAMS/CREEKS. AT THIS TIME CONFIDENCE IS LOW IN
DETERMINING THE EXACT LOCATION OF THE HEAVIEST RAIN BUT THE LARGE
SCALE PATTERN AND ATMOS MOISTURE IS SUPPORTIVE OF 2+ INCH AMOUNTS
IN A SHORT DURATION.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE/LAMBERT
NEAR TERM...LA CORTE/LAMBERT
SHORT TERM...LAMBERT
LONG TERM...GARTNER/STEINBUGL
AVIATION...FITZGERALD
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
453 AM EDT THU AUG 20 2015
.SYNOPSIS...
A WEAK COLD FRONT WILL APPROACH THE AREA FROM THE WEST TODAY
BRINGING INCREASED CHANCES FOR SHOWERS AND THUNDERSTORMS. IN THE
FRONTS WAKE...SOME DRYING IS EXPECTED OVER THE WEEKEND. ANOTHER WEAK
FRONT APPROACHES THE CAROLINAS ON MONDAY WITH HIGH PRESSURE MOVING
OVER THE REGION BEHIND THE FRONT.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 AM THURSDAY...BENIGN CONDITIONS AT AFD TIME...BUT THIS
AFTER QUITE AN EVENTFUL EVENING YESTERDAY. WARM RAIN PROCESSES AND
TRAINING CELLS RESULTED IN ANOTHER 5+ INCHES OF RAIN ACROSS PORTIONS
OF UNION COUNTY NC WHERE SOME SIGNIFICANT FLASH FLOODING WAS
REPORTED. GOOSE CREEK REMAINS HIGH WITH ONE POINT STILL IN FLOOD AT
AFD TIME.
ONTO THE FORECAST...DEEP UPPER TROUGH STRETCHING DOWN THE
MISSISSIPPI WILL BEGIN TO LIFT INTO THE GREAT LAKES AND SOUTHEAST
CANADA TODAY...WITH AN OCCLUDED COLD FRONT PUSHING TOWARD THE
SOUTHERN APPALACHIANS. THE SOUTHERN EDGE OF THE FRONT IS PROGGED TO
PUSH THROUGH THE FORECAST AREA TONIGHT BUT WASH OUT QUICKLY.
DEWPOINTS BY SUNRISE FRIDAY WILL ACTUALLY DROP INTO THE UPPER 60S
ACROSS THE UPSTATE WITH SOME UPPER 50S IN THE MOUNTAINS. WE WILL
ALSO SEE LOW TEMPERATURES A COUPLE OF DEGREES COOLER THAN WE HAVE
BEEN EXPERIENCING LATELY...BUT THE DECREASE IN DEWPOINTS WILL NOT BE
QUITE QUICK ENOUGH TO BRING LOWS DOWN TO SEASONAL NORMALS JUST YET.
ANOTHER WEAK SHORTWAVE DIVING TOWARD THE OHIO VALLEY TONIGHT...WITH
A FAIRLY POTENT VORT LOBE...WILL SERVE TO PULL UP ADDITIONAL
MOISTURE AS SURFACE PATTERN TRANSITIONS TO HIGH PRESSURE.
BIGGEST CONCERN OF THE NEAR TERM WILL BE CHANCE OF ADDITIONAL
CONVECTION TODAY. WITH THE APPROACH AND PASSAGE OF THE COLD FRONT...
CERTAINLY THERE IS ENOUGH SYNOPTIC FORCING...AND WITH PW VALUES
REMAINING GENERALLY AT OR ABOVE 2 INCHES...WE SHOULD CONTINUE TO SEE
FAIRLY EFFICIENT RAIN PRODUCERS. NOT GOOD NEWS FOR FOLKS THAT
EXPERIENCED SOME SIGNIFICANT RAINFALL AMOUNTS AND RESULTING FLASH
FLOODING LAST NIGHT. LUCKILY SBCAPE VALUES GENERALLY REMAIN BELOW
1000 J/KG SO CONVECTIVE INTENSITY SHOULD NOT BE QUITE AS BAD AS
YESTERDAY. ALL THAT SAID...HI-RES GUIDANCE NOT PARTICULARLY
IMPRESSED WITH CONVECTIVE POTENTIAL FOR THIS AFTERNOON. HRRR ONLY
HAS ISOLATED CONVECTION AT BEST EVEN THROUGH 20Z. WRF NMM AND ARW
REFLECTIVITY GUIDANCE ON PAR WITH THE HRRR. WITH THAT...KEPT POPS AT
CHANCE AT BEST ACROSS THE UPSTATE AND MOST OF THE NC PIEDMONT...WITH
LIKELIES IN THE MOUNTAINS. CONFIDENCE NOT PARTICULARLY HIGH SO WILL
HAVE TO MONITOR THROUGH THE DAY.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 310 AM EDT THURSDAY...THE SHORT TERM FCST PICKS UP AT 12Z ON
FRIDAY WITH THE UPPER TROF LIFTING NE OF THE GREAT LAKES AS HEIGHTS
BEGIN TO RISE OVER THE SE REGION. THIS PATTERN WILL PERSIST INTO THE
MEDIUM RANGE WITH VARIOUS LOBES OF SHORTWAVE ENERGY APPROACHING THE
CWFA FROM THE WEST OVER THE WEEKEND. IN ADDITION...ANOTHER COMPACT
UPPER TROF WILL DIG DOWN OVER THE US/CANADA BORDER OVER THE WEEKEND
AND MOVE ACROSS THE GREAT LAKES BY THE START OF THE MEDIUM RANGE.
ON FRIDAY...THE SFC HIGH GRADUALLY SLIDES EASTWARD AND THEN NE THRU
THE DAY AND EVENING WITH LOW LVL DRYING AS THE BNDY LAYER FLOW
BECOMES MORE NLY. THE GFS SOLUTION CONTINUES TO BE THE DRIEST MODEL
OVERALL WITH THE NAM BEING THE WETTEST. REGARDLESS OF MODEL
CHOICE...THE TREND IS FOR DRIER PROFILES AND LESS INFLUENCE FROM THE
GULF AS WE MOVE INTO SAT. ON SATURDAY...THE SFC HIGH SLIDES A BIT
FARTHER NE AND UP OVER NEW ENGLAND AS SOME WEAK WEDGING APPEARS TO
BRIEFLY DEVELOP OVER THE CAROLINAS. ANY WEDGING IS EXPECTED TO BE
SHORT LIVED WITH THE LOW LVL FLOW BECOMING WEAKER SAT AFTERNOON AND
EVENING. THE PERIOD ENDS EARLY SUN WITH THE NEXT COLD FRONT STILL
WELL TO OUR WEST AND MOSTLY LIGHT AND VRB FLOW OVER THE CWFA. AS FOR
THE SENSIBLE FCST...THE BEST CHANCES FOR ADDITIONAL PRECIP WILL BE
ON FRI WITH LOWER CHANCES FOR SAT AND SUN. MAX TEMPS WILL STRUGGLE
TO GET REACH CLIMO WHILE MIN TEMPS SHOULD START OUT ABOUT A CATEGORY
ABOVE AND COOL AROUND 2 TO 4 DEGREES THRU THE PERIOD.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 255 AM EDT THURSDAY...THE MEDIUM RANGE FCST BEGINS AT 12Z ON
SUNDAY WITH FLAT UPPER RIDGING OVER THE GULF OF MEX AND ANOTHER
UPPER TROF DIGGING DOWN OVER MINNESOTA AND THE WESTERN GREAT LAKES.
OVER THE REMAINDER OF THE PERIOD...THE LONG RANGE MODELS GRADUALLY
MOVE THE TROF EASTWARD AND EVENTUALLY LIFT IT NE OF NEW ENGLAND. THE
LATEST 00Z RUN OF THE GFS REMAINS FASTER WITH THE TROFS PROGRESSION
COMPARED TO THE ECMWF...HOWEVER THEY ARE MORE SIMILAR THAN BEFORE
WITH BOTH MODELS DEVELOPING A CLOSED LOW BY EARLY NEXT WEEK. THE
UPPER RIDGING WILL REAMPLIFY OVER THE CENTRAL CONUS IN THE TROFS
WAKE BY MID TO LATE NEXT WEEK WITH THE GFS STILL QUITE A BIT MORE
ROBUST WITH THE RIDGE. AT THE SFC...LINGERING HIGH PRESSURE WILL BE
IN PLACE OVER THE REGION ON SUNDAY. ANOTHER COLD FRONT WILL APPROACH
THE CWFA LATE SUN/EARLY MON AND MOVE ACROSS THE CWFA DURING THE DAY.
THE GFS CONTINUES TO BE FASTER AND A BIT DRIER OVERALL WITH THE
FROPA COMPARED TO THE ECMWF...YET BOTH MODELS ARE LOOKING PRETTY DRY
AT THIS POINT. ANOTHER HIGH WILL PUSH INTO THE REGION BEHIND THE
FRONT ON TUES AND LINGER THRU THE REMAINDER OF THE MEDIUM RANGE.
AS FOR THE SENSIBLE WX...NO SIGNIFICANT CHANGES WERE NEEDED WITH A
SLIGHT TO SOLID CHANCE POP EACH DAY AND TEMPS JUST ABOVE NORMAL FOR
LATE AUGUST.
&&
.AVIATION /09Z THURSDAY THROUGH MONDAY/...
AT KCLT...OVERALL NO CHANGE TO THINKING FOR THE KCLT TAF FOR THE 09Z
AMD. GUIDANCE SEEMS LESS PESSIMISTIC IN DEVELOPMENT OF MVFR
RESTRICTIONS THIS MORNING BUT FOR NOW WILL LEAVE TAF AS-IS GIVEN
NEARBY OBS. EXPECT IMPROVING CONDITIONS AFTER 14-15Z OR SO...WITH
ANOTHER ROUND OF TSRA POSSIBLE THIS AFTERNOON SO HAVE INTRODUCED
PROB30. WINDS GENERALLY SW THROUGH THE PERIOD BELOW 5KT...THOUGH
COULD SEE VRB GUSTY WINDS IN/NEAR TSRA.
ELSEWHERE...STILL SOME -SHRA ESPECIALLY ON FOR KAVL/KHKY/KAND
POSSIBLE ON AND OFF THE NEXT FEW HOURS. ALREADY SEEING INTERMITTENT
IFR CONDITIONS AT KAVL/KHKY AND THIS WILL CONTINUE THROUGH THE
MORNING HOURS. WILL PROBABLY SEE AT LEAST MVFR CONDITIONS...IF NOT
BRIEF IFR...AT THE UPSTATE TAFS TOWARD SUNRISE AS WELL. EXPECTED
IMPROVING CONDITIONS AFTER 14-15Z OR SO...WITH ANOTHER ROUND OF TSRA
POSSIBLE THIS AFTERNOON. KEPT PROB30 FOR KAVL/KHKY AND INTRODUCED IT
AT UPSTATE TAFS. WINDS GENERALLY SW THROUGH THE PERIOD BELOW 5KT...
THOUGH COULD SEE VRB GUSTY WINDS IN/NEAR TSRA.
OUTLOOK...A COLD FRONT WILL PUSH THROUGH THE AREA LATE THURSDAY AND
THURSDAY NIGHT. ASSOCIATED SHOWERS/THUNDERSTORMS ARE EXPECTED TO END
THURSDAY NIGHT. LINGERING LOW LEVEL MOISTURE MAY RESULT IN
RESTRICTIONS IN FOG/STRATUS EARLY FRIDAY. DRY HIGH PRESSURE BUILDING
IN FROM THE NORTH WILL LIMIT RESTRICTIONS THROUGH THE WEEKEND.
CONFIDENCE TABLE...
09-15Z 15-21Z 21-03Z 03-06Z
KCLT HIGH 82% HIGH 96% HIGH 100% HIGH 100%
KGSP HIGH 87% HIGH 100% HIGH 100% HIGH 100%
KAVL MED 72% HIGH 100% HIGH 100% HIGH 100%
KHKY MED 74% HIGH 100% HIGH 100% HIGH 100%
KGMU MED 67% HIGH 100% HIGH 100% HIGH 100%
KAND MED 72% HIGH 90% HIGH 100% 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
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...TDP
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...TDP
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
324 AM EDT THU AUG 20 2015
.SYNOPSIS...
A WEAK COLD FRONT WILL APPROACH THE AREA FROM THE WEST TODAY
BRINGING INCREASED CHANCES FOR SHOWERS AND THUNDERSTORMS. IN THE
FRONTS WAKE...SOME DRYING IS EXPECTED OVER THE WEEKEND. ANOTHER WEAK
FRONT APPROACHES THE CAROLINAS ON MONDAY WITH HIGH PRESSURE MOVING
OVER THE REGION BEHIND THE FRONT.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 AM THURSDAY...BENIGN CONDITIONS AT AFD TIME...BUT THIS
AFTER QUITE AN EVENTFUL EVENING YESTERDAY. WARM RAIN PROCESSES AND
TRAINING CELLS RESULTED IN ANOTHER 5+ INCHES OF RAIN ACROSS PORTIONS
OF UNION COUNTY NC WHERE SOME SIGNIFICANT FLASH FLOODING WAS
REPORTED. GOOSE CREEK REMAINS HIGH WITH ONE POINT STILL IN FLOOD AT
AFD TIME.
ONTO THE FORECAST...DEEP UPPER TROUGH STRETCHING DOWN THE
MISSISSIPPI WILL BEGIN TO LIFT INTO THE GREAT LAKES AND SOUTHEAST
CANADA TODAY...WITH AN OCCLUDED COLD FRONT PUSHING TOWARD THE
SOUTHERN APPALACHIANS. THE SOUTHERN EDGE OF THE FRONT IS PROGGED TO
PUSH THROUGH THE FORECAST AREA TONIGHT BUT WASH OUT QUICKLY.
DEWPOINTS BY SUNRISE FRIDAY WILL ACTUALLY DROP INTO THE UPPER 60S
ACROSS THE UPSTATE WITH SOME UPPER 50S IN THE MOUNTAINS. WE WILL
ALSO SEE LOW TEMPERATURES A COUPLE OF DEGREES COOLER THAN WE HAVE
BEEN EXPERIENCING LATELY...BUT THE DECREASE IN DEWPOINTS WILL NOT BE
QUITE QUICK ENOUGH TO BRING LOWS DOWN TO SEASONAL NORMALS JUST YET.
ANOTHER WEAK SHORTWAVE DIVING TOWARD THE OHIO VALLEY TONIGHT...WITH
A FAIRLY POTENT VORT LOBE...WILL SERVE TO PULL UP ADDITIONAL
MOISTURE AS SURFACE PATTERN TRANSITIONS TO HIGH PRESSURE.
BIGGEST CONCERN OF THE NEAR TERM WILL BE CHANCE OF ADDITIONAL
CONVECTION TODAY. WITH THE APPROACH AND PASSAGE OF THE COLD FRONT...
CERTAINLY THERE IS ENOUGH SYNOPTIC FORCING...AND WITH PW VALUES
REMAINING GENERALLY AT OR ABOVE 2 INCHES...WE SHOULD CONTINUE TO SEE
FAIRLY EFFICIENT RAIN PRODUCERS. NOT GOOD NEWS FOR FOLKS THAT
EXPERIENCED SOME SIGNIFICANT RAINFALL AMOUNTS AND RESULTING FLASH
FLOODING LAST NIGHT. LUCKILY SBCAPE VALUES GENERALLY REMAIN BELOW
1000 J/KG SO CONVECTIVE INTENSITY SHOULD NOT BE QUITE AS BAD AS
YESTERDAY. ALL THAT SAID...HI-RES GUIDANCE NOT PARTICULARLY
IMPRESSED WITH CONVECTIVE POTENTIAL FOR THIS AFTERNOON. HRRR ONLY
HAS ISOLATED CONVECTION AT BEST EVEN THROUGH 20Z. WRF NMM AND ARW
REFLECTIVITY GUIDANCE ON PAR WITH THE HRRR. WITH THAT...KEPT POPS AT
CHANCE AT BEST ACROSS THE UPSTATE AND MOST OF THE NC PIEDMONT...WITH
LIKELIES IN THE MOUNTAINS. CONFIDENCE NOT PARTICULARLY HIGH SO WILL
HAVE TO MONITOR THROUGH THE DAY.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 310 AM EDT THURSDAY...THE SHORT TERM FCST PICKS UP AT 12Z ON
FRIDAY WITH THE UPPER TROF LIFTING NE OF THE GREAT LAKES AS HEIGHTS
BEGIN TO RISE OVER THE SE REGION. THIS PATTERN WILL PERSIST INTO THE
MEDIUM RANGE WITH VARIOUS LOBES OF SHORTWAVE ENERGY APPROACHING THE
CWFA FROM THE WEST OVER THE WEEKEND. IN ADDITION...ANOTHER COMPACT
UPPER TROF WILL DIG DOWN OVER THE US/CANADA BORDER OVER THE WEEKEND
AND MOVE ACROSS THE GREAT LAKES BY THE START OF THE MEDIUM RANGE.
ON FRIDAY...THE SFC HIGH GRADUALLY SLIDES EASTWARD AND THEN NE THRU
THE DAY AND EVENING WITH LOW LVL DRYING AS THE BNDY LAYER FLOW
BECOMES MORE NLY. THE GFS SOLUTION CONTINUES TO BE THE DRIEST MODEL
OVERALL WITH THE NAM BEING THE WETTEST. REGARDLESS OF MODEL
CHOICE...THE TREND IS FOR DRIER PROFILES AND LESS INFLUENCE FROM THE
GULF AS WE MOVE INTO SAT. ON SATURDAY...THE SFC HIGH SLIDES A BIT
FARTHER NE AND UP OVER NEW ENGLAND AS SOME WEAK WEDGING APPEARS TO
BRIEFLY DEVELOP OVER THE CAROLINAS. ANY WEDGING IS EXPECTED TO BE
SHORT LIVED WITH THE LOW LVL FLOW BECOMING WEAKER SAT AFTERNOON AND
EVENING. THE PERIOD ENDS EARLY SUN WITH THE NEXT COLD FRONT STILL
WELL TO OUR WEST AND MOSTLY LIGHT AND VRB FLOW OVER THE CWFA. AS FOR
THE SENSIBLE FCST...THE BEST CHANCES FOR ADDITIONAL PRECIP WILL BE
ON FRI WITH LOWER CHANCES FOR SAT AND SUN. MAX TEMPS WILL STRUGGLE
TO GET REACH CLIMO WHILE MIN TEMPS SHOULD START OUT ABOUT A CATEGORY
ABOVE AND COOL AROUND 2 TO 4 DEGREES THRU THE PERIOD.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 255 AM EDT THURSDAY...THE MEDIUM RANGE FCST BEGINS AT 12Z ON
SUNDAY WITH FLAT UPPER RIDGING OVER THE GULF OF MEX AND ANOTHER
UPPER TROF DIGGING DOWN OVER MINNESOTA AND THE WESTERN GREAT LAKES.
OVER THE REMAINDER OF THE PERIOD...THE LONG RANGE MODELS GRADUALLY
MOVE THE TROF EASTWARD AND EVENTUALLY LIFT IT NE OF NEW ENGLAND. THE
LATEST 00Z RUN OF THE GFS REMAINS FASTER WITH THE TROFS PROGRESSION
COMPARED TO THE ECMWF...HOWEVER THEY ARE MORE SIMILAR THAN BEFORE
WITH BOTH MODELS DEVELOPING A CLOSED LOW BY EARLY NEXT WEEK. THE
UPPER RIDGING WILL REAMPLIFY OVER THE CENTRAL CONUS IN THE TROFS
WAKE BY MID TO LATE NEXT WEEK WITH THE GFS STILL QUITE A BIT MORE
ROBUST WITH THE RIDGE. AT THE SFC...LINGERING HIGH PRESSURE WILL BE
IN PLACE OVER THE REGION ON SUNDAY. ANOTHER COLD FRONT WILL APPROACH
THE CWFA LATE SUN/EARLY MON AND MOVE ACROSS THE CWFA DURING THE DAY.
THE GFS CONTINUES TO BE FASTER AND A BIT DRIER OVERALL WITH THE
FROPA COMPARED TO THE ECMWF...YET BOTH MODELS ARE LOOKING PRETTY DRY
AT THIS POINT. ANOTHER HIGH WILL PUSH INTO THE REGION BEHIND THE
FRONT ON TUES AND LINGER THRU THE REMAINDER OF THE MEDIUM RANGE.
AS FOR THE SENSIBLE WX...NO SIGNIFICANT CHANGES WERE NEEDED WITH A
SLIGHT TO SOLID CHANCE POP EACH DAY AND TEMPS JUST ABOVE NORMAL FOR
LATE AUGUST.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
AT KCLT...TSRA HAS MOVED OUT FOR THE NIGHT. HOWEVER...DUE TO HIGH
MOISTURE LEVELS AND RAIN FROM YESTERDAY...EXPECT SOME MVFR VSBYS TO
DEVELOP THROUGH JUST AFTER SUNRISE...WITH MVFR CIGS POSSIBLE AS
WELL. CANNOT RULE OUT LOWER CIGS/VSBY BUT CONFIDENCE NOT
PARTICULARLY HIGH. EXPECTED IMPROVING CONDITIONS AFTER 14-15Z OR
SO...WITH ANOTHER ROUND OF TSRA POSSIBLE THIS AFTERNOON SO HAVE
INTRODUCED PROB30. WINDS GENERALLY SW THROUGH THE PERIOD BELOW
5KT...THOUGH COULD SEE VRB GUSTY WINDS IN/NEAR TSRA.
ELSEWHERE...STILL SOME -SHRA ESPECIALLY ON FOR KAVL/KHKY/KAND
POSSIBLE ON AND OFF THE NEXT FEW HOURS. ALREADY SEEING INTERMITTENT
IFR CONDITIONS AT KAVL/KHKY AND THIS WILL CONTINUE THROUGH THE
MORNING HOURS. WILL PROBABLY SEE AT LEAST MVFR CONDITIONS...IF NOT
BRIEF IFR...AT THE UPSTATE TAFS TOWARD SUNRISE AS WELL. EXPECTED
IMPROVING CONDITIONS AFTER 14-15Z OR SO...WITH ANOTHER ROUND OF TSRA
POSSIBLE THIS AFTERNOON. KEPT PROB30 FOR KAVL/KHKY AND INTRODUCED IT
AT UPSTATE TAFS. WINDS GENERALLY SW THROUGH THE PERIOD BELOW 5KT...
THOUGH COULD SEE VRB GUSTY WINDS IN/NEAR TSRA.
OUTLOOK...A COLD FRONT WILL PUSH THROUGH THE AREA LATE THURSDAY AND
THURSDAY NIGHT. ASSOCIATED SHOWERS/THUNDERSTORMS ARE EXPECTED TO END
THURSDAY NIGHT. LINGERING LOW LEVEL MOISTURE MAY RESULT IN
RESTRICTIONS IN FOG/STRATUS EARLY FRIDAY. DRY HIGH PRESSURE BUILDING
IN FROM THE NORTH WILL LIMIT RESTRICTIONS THROUGH THE WEEKEND.
CONFIDENCE TABLE...
07-13Z 13-19Z 19-01Z 01-06Z
KCLT HIGH 86% HIGH 84% HIGH 100% HIGH 100%
KGSP HIGH 90% HIGH 100% HIGH 100% HIGH 100%
KAVL MED 71% HIGH 92% HIGH 100% HIGH 100%
KHKY MED 68% HIGH 92% HIGH 100% HIGH 100%
KGMU MED 73% HIGH 92% HIGH 100% HIGH 100%
KAND MED 73% HIGH 83% HIGH 100% 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
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...TDP
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...TDP
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
140 AM EDT THU AUG 20 2015
.SYNOPSIS...
A WEAK FRONT WILL APPROACH THE AREA ON THURSDAY...PRECEDED BY
SHOWERS AND THUNDERSTORMS. SOME DRYING IS EXPECTED OVER THE WEEKEND.
ANOTHER WEAK FRONT APPROACHES OUR AREA EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 750 PM WED...THUNDERSHOWER ACTIVITY IS BEGINNING TO SETTLE
DOWN AS EXPECTED WITH THE ONLY HEAVY STORM IN THE AREA CONTINUING
OVER UNION COUNTY WITH CONTINUED MODERATE TO HEAVY RAINFALL FOR THE
NEXT HOUR OR TWO. ALL BUT LIGHT ACTIVITY IS EXPECTED TO END IN THE
NEXT 2 OR 3 HOURS. SOME AREAS HAVE RECEIVED VERY HEAVY RAINFALL
TODAY AND YESTERDAY WHICH IS LEADING TO SIGNIFICANT LOCALIZED
FLOODING. CHANCES FOR MORE RAIN CONTINUE TOMORROW...THOUGH THE
PROBABILITY OF PRECIP. IS NOT AS HIGH AS WAS SEEN TODAY.
AS OF 510 PM WED...UPDATED FORECAST TO CONCENTRATE PRECIPITATION TO
EASTERN PARTS OF THE CWA PER RADAR TRENDS AND HRRR GUIDANCE. RADAR
HAS HAD HEAVIEST COVERAGE OF THUNDERSTORMS MOVING EASTWARD WITH SOME
RESIDUAL ACTIVITY ELSEWHERE. HEAVIER STORMS OVER EASTERN PARTS OF
THE CWA AGREES WITH HIGHER CAPE ANALYSIS IN THAT AREA. RAINFALL
AMOUNTS WILL CONTINUE TO BE GENEROUS...GIVEN HIGH PRECIPITABLE
WATER. SHOWERS WILL BEGIN TO TAPER AFTER 3Z THIS EVENING.
AS OF 230 PM WED...RADAR CONTINUES TO SHOW INCREASING COVERAGE AND
EXPECT NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS THE AREA THROUGH
THE AFTERNOON. SOME MORE STRATIFORM TYPE PRECIP WITH EMBEDDED
THUNDER MAY LINGER INTO THE EVENING HOURS OVER EASTERN AREAS. SPC
MESOANAL SHOWING CAPES IN THE 2000-3000J/KG RANGE OUTSIDE THE
MOUNTAINS. ALSO...THE DCAPE HIGHER TODAY THAN PREVIOUS DAYS NOW
HAVING INCREASED TO OVER 1000J EASTERN AREAS. HENCE...SEVERE STORM
CHANCES HIGHER THIS AFTERNOON AND WE SHOULD SEE SEVERAL PULSE SEVERE
STORMS. THE SEVERE THREAT WILL BE ALONG SIDE THE LOCALIZED HYDRO
THREAT.
IN REGARD TO THE BIG PICTURE...A VORT MAX IS FORECAST TO MOVE ACROSS
THE AREA DURING THE LATE AFTERNOON AND EVENING HOURS WHICH IS THE
PRIMARY TRIGGER OF THE NUMEROUS SHOWERS AND STORMS. NVA BEHIND THIS
FEATURE SHOULD RESULT IN A LULL IN PRECIP COVERAGE DURING THE
OVERNIGHT HOURS. MINIMUM TEMPS ARE EXPECTED TO BE ABOUT A CATEGORY
ABOVE CLIMO.
ON THURSDAY...A DEEP UPPER TROUGH SWINGING THROUGH THE GREAT LAKES
WILL PUSH A COLD FRONT SOUTHEASTWARD AND IT IS FORECAST TO REACH THE
MOUNTAINS DURING THE AFTERNOON. WITH DEEP LAYER MOISTURE STILL IN
PLACE...THERE STILL SHOULD BE DECENT COVERAGE OF SHOWERS AND
THUNDERSTORMS IN THE MOUNTAINS. HOWEVER EAST OF THE MOUNTAINS...WITH
FLOW BECOMING MORE ZONAL/DOWNSLOPE THE COVERAGE SHOULD BE SCT. MODEL
FORECAST SOUNDINGS ALSO INDICATE LESS CAPE...SO SEVERE THREAT
APPEARS ON THE LOW END. MAX TEMPS WILL BE NEAR TO CLIMO.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
AS OF 200 PM EDT WEDNESDAY...THE SHORT TERM FCST PERIOD INITIALIZES
THURSDAY EVENING AMIDST AN ONGOING COLD FRONTAL INTRUSION.
THE UPPER PATTERN WILL BE HIGHLIGHTED BY A DEEP NEGATIVELY TILTED
LONGWAVE TROF EJECTING THROUGH THE GREAT LAKES WHILE BROAD RIDGING
PREVAILS OVER THE DEEP SOUTH AND EASTERN GULF. AS STATED ABOVE...A
COLD FRONT WILL BE WORKING ITS WAY INTO/THROUGH THE NC HIGH TERRAIN
BY THURSDAY EVENING WITH DEEP SOUTHWESTERLY FLOW PREVAILING OUT
AHEAD. IN RESPONSE...EXPECTING ONGOING CONVECTION IN THE WARM
SECTOR AT FCST INITIALIZATION POSSIBLY AIDED BY ENHANCED SHEARING
AND VORT ADVECTION ALOFT. SHORT TERM GUIDANCE IS NOW IN BETTER
AGREEMENT WITH REGARDS TO THE TRACK/DEPTH OF THE FRONTAL PASSAGE
WITH BOTH THE GFS/NAM ALONG WITH THE ECMWF PUSHING THE BOUNDARY
SOUTH OF THE CWFA...LIKELY WASHING OUT OVER THE LOWCOUNTRY/MIDLANDS
BY MID MORNING FRIDAY.
BROAD SFC HIGH PRESSURE IS FCST TO ADVECT IN FROM THE MIDWEST
INTO THE OHIO VALLEY JUST BEHIND THE FRONT...BEFORE SLIDING OVER
THE SOUTHERN/CENTRAL APPS LATER IN THE DAY. AS A RESULT...DRIER
NORTHERLY FLOW WILL WARRANT DECREASED PRECIPITATION POTENTIAL
AND PARTLY CLOUDY SKIES ACROSS MUCH OF WESTERN NC. DUE TO CLOSER
PROXIMITY TO ANY REMNANT FRONTAL MOISTURE...LOCATIONS ALONG AND
SOUTH OF THE I85 CORRIDOR WILL SEE SLIGHTLY HIGH PROBABILITIES AND
THUS PARTLY/MOSTLY CLOUDY SKIES. NEVERTHELESS...PROFILES ARE NOT
SUPPORTIVE OF ANY DEEP CONVECTION AT THIS TIME THEREFORE NOTHING
MORE THAN GARDEN VARIETY SHOWERS WITH PERHAPS A FEW RUMBLES OF
THUNDER ARE EXPECTED. SATURDAY IS SHAPING UP TO BE THE NICEST DAY
OF THE PERIOD WITH MODELS INDICATING FURTHER DRY AIR INTRUSION
AS THE ABOVE MENTIONED SURFACE RIDGE MOVES EAST OF THE APPS.
MOSGUIDE AND TO SOME EXTENT EVEN THE RAW NAM INDICATES DEWPOINTS
IN THE UPPER 50S ACROSS NORTHWEST NC INCREASING TO THE LOWER 60S
ALONG THE I85 CORRIDOR. THUS EXPECTING MOSTLY SUNNY TO PARTLY
CLOUDY SKIES AND TEMPERATURES A FEW DEGREES BELOW NORMAL ALLOWING
FOR A BEAUTIFUL MID/LATE AUGUST DAY. THAT SAID...NAM GUID DOES
FAVORS AT LEAST SOME CHANCE FOR LOW END DESTABILIZATION OVER THE
SOUTHWEST NC MOUNTAINS AND NORTHEAST GA...THEREFORE WILL INCLUDE
POPS TO ACCOUNT FOR SUCH WITH MAX HEATING ON SATURDAY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AT 230 PM EDT WEDNESDAY...ON SUNDAY AN UPPER RIDGE WILL BE OVER THE
WESTERN USA...WITH A MEAN TROUGH OVER THE EAST. THE PATTERN
AMPLIFIES SLIGHTLY INTO TUESDAY AS A CLOSED UPPER LOW CROSSES SOUTH
CENTRAL CANADA. THE PATTERN DEAMPLIFIES SLIGHTLY BY THURSDAY AS THE
CANADIAN LOW APPROACHES THE ATLANTIC....BY WHICH TIME SOME
PROGRESSION TAKES PLACE...AND THE UPPER TROUGH REACHES THE EASTERN
SEABOARD...WHILE THE RIDGE UPSTREAM CROSSES THE PLAINS AND EXTENDS
INTO THE GULF STATES.
AT THE SURFACE...SUNDAY STARTS OUT WITH HIGH PRESSURE ALONG THE
EASTERN SEABOARD...WITH A COLD FRONT UPSTREAM FORM THE GREAT LAKES
TO THE SOUTHERN PLAINS. THIS FRONT REACHES THE SOUTHERN APPALACHIANS
ON MONDAY...MOVING TO THE COASTAL PLAIN BY TUESDAY...WHERE IT STALLS
AND REMAINS INTO WEDNESDAY. OUR AREA CAN EXPECT AN ACTIVE PATTERN
AHEAD OF AND ALONG THE FRONT...WITH A DRYING TREND IN THE
WAKE OF THE FRONT. AT THIS TIME...PRECIPITATION AMOUNTS ARE NOT
EXPECTED TO BE EXCESSIVE AS THE FRONT DOES NOT STALL UNTIL EAST OF
OUR AREA. TEMPERATURES WILL RUN NEAR NORMAL.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AT KCLT...TSRA HAS MOVED OUT FOR THE NIGHT. HOWEVER...DUE TO HIGH
MOISTURE LEVELS AND RAIN FROM YESTERDAY...EXPECT SOME MVFR VSBYS TO
DEVELOP THROUGH JUST AFTER SUNRISE...WITH MVFR CIGS POSSIBLE AS
WELL. CANNOT RULE OUT LOWER CIGS/VSBY BUT CONFIDENCE NOT
PARTICULARLY HIGH. EXPECTED IMPROVING CONDITIONS AFTER 14-15Z OR
SO...WITH ANOTHER ROUND OF TSRA POSSIBLE THIS AFTERNOON SO HAVE
INTRODUCED PROB30. WINDS GENERALLY SW THROUGH THE PERIOD BELOW
5KT...THOUGH COULD SEE VRB GUSTY WINDS IN/NEAR TSRA.
ELSEWHERE...STILL SOME -SHRA ESPECIALLY ON FOR KAVL/KHKY/KAND
POSSIBLE ON AND OFF THE NEXT FEW HOURS. ALREADY SEEING INTERMITTENT
IFR CONDITIONS AT KAVL/KHKY AND THIS WILL CONTINUE THROUGH THE
MORNING HOURS. WILL PROBABLY SEE AT LEAST MVFR CONDITIONS...IF NOT
BRIEF IFR...AT THE UPSTATE TAFS TOWARD SUNRISE AS WELL. EXPECTED
IMPROVING CONDITIONS AFTER 14-15Z OR SO...WITH ANOTHER ROUND OF TSRA
POSSIBLE THIS AFTERNOON. KEPT PROB30 FOR KAVL/KHKY AND INTRODUCED IT
AT UPSTATE TAFS. WINDS GENERALLY SW THROUGH THE PERIOD BELOW 5KT...
THOUGH COULD SEE VRB GUSTY WINDS IN/NEAR TSRA.
OUTLOOK...A COLD FRONT WILL PUSH THROUGH THE AREA LATE THURSDAY AND
THURSDAY NIGHT. ASSOCIATED SHOWERS/THUNDERSTORMS ARE EXPECTED TO END
THURSDAY NIGHT. LINGERING LOW LEVEL MOISTURE MAY RESULT IN
RESTRICTIONS IN FOG/STRATUS EARLY FRIDAY. DRY HIGH PRESSURE BUILDING
IN FROM THE NORTH WILL LIMIT RESTRICTIONS THROUGH THE WEEKEND.
CONFIDENCE TABLE...
05-11Z 11-17Z 17-23Z 23-00Z
KCLT HIGH 100% LOW 51% HIGH 95% HIGH 100%
KGSP HIGH 100% MED 68% HIGH 100% LOW 57%
KAVL HIGH 100% LOW 56% HIGH 100% HIGH 100%
KHKY HIGH 87% HIGH 85% HIGH 100% HIGH 100%
KGMU HIGH 100% HIGH 80% HIGH 100% LOW 57%
KAND HIGH 87% LOW 46% HIGH 95% LOW 57%
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
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JAT
NEAR TERM...LG/WJM
SHORT TERM...CDG
LONG TERM...JAT
AVIATION...TDP
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1156 PM CDT WED AUG 19 2015
.AVIATION...
/06Z TAF/ A BROAD SWATH OF SHOWERS ALONG THE I-20 CORRIDOR WILL
PERSIST THROUGH 12Z AND SAG SOUTHWARD AS BEST LOW/MID LEVEL
FORCING GRADUALLY SHIFTS TOWARD CENTRAL TEXAS OVERNIGHT. SOME WEAK
INSTABILITY STILL EXISTS ACROSS THE REGION NORTH OF THE COLD
FRONT WHICH SWEPT THROUGH THE AREA TODAY. HOWEVER..WITH LIGHTNING
OCCURRENCE AND INTENSITY VERY LOW...WILL LEAVE MENTION OF THUNDER
OUT OF NEXT TAF ISSUANCES. A FEW SHOWERS MAY LINGER IN THE
METROPLEX AND WACO THROUGH DAYBREAK...BUT BELIEVE MOST
PRECIPITATION WILL BE SOUTH OF ALL N TEXAS AIRPORTS BY LATE THURS
MORNING. CONFIDENCE IN ADDITIONAL SIGNIFICANT SHOWER ACTIVITY WAS
NOT SUBSTANTIAL ENOUGH TO INCLUDE MENTION AFTER 10Z.
AS SHOWERS CONTINUE (OR IN THE CASE OF KACT: DEVELOP)...EXPECT
LOWER ATMOSPHERIC LAYERS TO BECOME SATURATED IN A FEW HOURS...PRODUCING
MVFR CIGS AFTER 08Z AT MOST SITES. SKIES SHOULD TRANSITION TO BKN
VFR CONDITIONS BY AROUND 15Z THURS...THEN EVENTUALLY SCATTERING
OUT AFTER NOON AS DRIER AIR BUILDS IN FROM THE NE.
NORTHEASTERLY LOW LEVEL WIND FLOW WILL GRADUALLY VEER TO AN
EASTERLY DIRECTION BY LATE THURSDAY MORNING...AVERAGING 7-10KTS AT
MOST SITES.
BRADSHAW
&&
.UPDATE...
A STRONG SURFACE COLD FRONT WILL CONTINUE MOVING THROUGH OUR
CENTRAL TEXAS COUNTIES THIS EVENING AND TOWARD THE TEXAS UPPER
COAST THROUGH THURSDAY MORNING. MEANWHILE...A SHORTWAVE TROUGH
ALOFT WILL SHIFT EASTWARD OVER THE AREA TONIGHT WITH THE 850MB
FRONT CURRENTLY TO OUR NORTHWEST MOVING THROUGH BY MORNING.
THE COMBINATION OF WEAK WAA OVER THE TOP OF THE 850MB FRONT...
RICH MOISTURE IN THE 850-700MB COLUMN ON THE 00Z FWD SOUNDING AND
FORCING FROM THE SHORTWAVE WILL RESULT IN MOSTLY LIGHT SHOWERS
ACROSS THE NORTH INTO THE PRE-DAWN HOURS WITH A CHANCE OF SHOWERS
AND THUNDERSTORMS IN VICINITY OF THE SURFACE COLD FRONT ACROSS THE
SOUTHEAST COUNTIES OVERNIGHT AND EARLY THURSDAY MORNING. DRIER AND
COOLER AIR SHOULD CONTINUE TO FILTER IN FROM THE NORTH AND NORTHWEST
WITH PRECIPITATION CHANCES ENDING ACROSS THE IMMEDIATE RED RIVER
VALLEY SHORTLY AFTER MIDNIGHT AS THE SHORTWAVE TROUGH AXIS AND
ELEVATED FRONT ROTATE THROUGH. AREAS NORTH OF I-20 SHOULD CLEAR
OUT FIRST WITH MANY AREAS SEEING COMFORTABLY COOL MORNING LOWS
FROM THE MID 50S TO LOWER 60S...WITH MID 60S TO LOWER 70S FURTHER
SOUTH.
WILL HOLD CHANCE POPS FOR THE ENTIRE AREA OVERNIGHT WITH BEST
CHANCES ACROSS OUR SOUTHEAST COUNTIES WHERE MOISTURE...INSTABILITY
AND FORCING WILL SUSTAIN THE LONGEST. NO SEVERE WEATHER IS
EXPECTED. CLEARING OF CLOUDS AND ASSOCIATED PRECIPITATION SHOULD
CONTINUE INTO THURSDAY...AS THE SHORTWAVE TROUGH CONTINUES
PROGRESSING EAST.
05/
&&
.SYNOPSIS...
THE MAIN STORY WITH THIS FORECAST PACKAGE WILL BE THE COOLER
WEATHER AND RAIN CHANCES OVER THE NEXT 12-24 HOURS. A RETURN TO
WARM CONDITIONS IS EXPECTED LATER THIS WEEK AND THROUGH THE
WEEKEND WITH LOWER CHANCES FOR PRECIPITATION.
&&
.SHORT TERM (TONIGHT THROUGH FRIDAY)...
A VERY DIFFICULT FORECAST EXISTS WITH SOME DIFFERENCES BETWEEN
BOTH HI-RES AND COARSE MODEL SOLUTIONS. AS IS OFTEN THE
CASE...NUMERICAL WEATHER PREDICTION OFTEN STRUGGLES WITH EVENTS
THAT ARE EITHER WEAKLY FORCED OR PRIMARILY DRIVEN BY MESOSCALE
PHENOMENON. IN THE CASE OF TODAY...A BULK OF THE LARGE SCALE
FORCING FOR ASCENT WAS DISPLACED WELL TO THE NORTH OF
NORTH/CENTRAL TEXAS AND THE MAIN FOCUSING MECHANISMS FOR WHAT RAIN
DID FALL THIS MORNING AND THIS AFTERNOON WERE OUTFLOW BOUNDARIES
FROM PREVIOUS CONVECTION ACROSS OK AND THE TX PANHANDLE.
MOST OF THE CONVECTION THIS AFTERNOON ON AREA RADARS APPEAR TO BE
ALONG THE FRONT WHERE SUFFICIENT LOW LEVEL CONVERGENCE IS
OCCURRING. WITH THE FRONT STARTING TO QUICKLY MOVE SOUTHWARD MOST
OF THIS ACTIVITY IS SHORT LIVED AS IT IS BEING UNDERCUT BY THE
SHALLOWER/COOLER AIR.
FOR THE REST OF THE AFTERNOON AND TONIGHT...STILL FEEL CONFIDENT
ENOUGH THAT THERE WILL BE A COUPLE OF AREAS THAT COULD SEE SOME
MEASURABLE PRECIPITATION. THE FIRST WILL BE ALONG OUR SOUTHEAST
ZONES NEAR THE SFC-925 MB FRONT LATER THIS AFTERNOON AND INTO
TONIGHT. MOST COARSE MODELS /EXCLUDING THE NAM/ SUGGEST THAT SOME
LOW LEVEL FRONTOGENESIS WILL OCCUR AND SHOULD YIELD ISOLATED TO
SCATTERED CONVECTION. THE OVERALL SEVERE POTENTIAL SEEMS
RELATIVELY LOW...BUT GIVEN THE UNSTABLE AIRMASS AHEAD OF THE
FRONT...WOULD NOT RULE OUT A STRONG DOWNBURST OR TWO. THERE MAY BE
A SMALL HAIL RISK WITH CONVECTION NEAR THE FRONT...BUT THINK THAT
CONVECTION IS BECOMING UNDERCUT TOO QUICKLY BEFORE HAIL PRODUCTION
CAN OCCUR.
THE SECOND AREA WITH A SLIGHTLY HIGHER CHANCE FOR PRECIPITATION
WILL BE ALONG AND NORTH OF THE INTERSTATE 20 CORRIDOR WHERE 850 MB
FRONTOGENETIC FORCING IS BEING ADVERTISED. PER THE TTU WRF AND
LATEST HRRR SOME AREAS OF ISOLATED TO WIDELY SCATTERED ACTIVITY IS
EXPECTED TO DEVELOP DURING THE OVERNIGHT HOURS INTO EARLY THURSDAY
MORNING. CLOSER TO SUNRISE...THIS ACTIVITY SHOULD SHIFT SOUTHWARD
AS DRIER AIR WORKS ITS WAY IN FROM THE NORTH. CURRENTLY THINK THAT
SOME SKIES ACROSS OUR IMMEDIATE RED RIVER ZONES MAY CLEAR ENOUGH
TO ALLOW FOR SOME DECENT COOLING. WITH THE CONTINUED NORTH
WINDS...THIS SHOULD ALLOW TEMPERATURES TO FALL INTO THE 60S WITH
PERHAPS EVEN A FEW UPPER 50S ALONG THE RED RIVER.
FOR THURSDAY AND THURSDAY NIGHT...THE HIGHEST RAIN CHANCES WILL
REMAIN DOWN ALONG OUR SOUTHEASTERN ZONES WHERE THE FRONT WILL
STALL AND BEGIN TO LOSE ITS BAROCLINICITY. MAX TEMPERATURES WILL
DEPEND ON THE AMOUNT OF SUNSHINE THAT CAN FILTER IN TO HELP OFFSET
SOME OF THE COLD AIR ADVECTION. IN GENERAL THINK THAT HIGHS WILL
CLIMB INTO THE LOW TO MID 80S...EXCEPT ACROSS FAR SOUTHEASTERN
ZONES WHERE UPPER 80S MAY BE POSSIBLE...ESPECIALLY IF THE FRONT
STALLS FURTHER NORTH THAN CURRENT EXPECTATIONS. WITH THE ZONAL
FLOW ALOFT ACROSS THE CENTRAL PLAINS...LOW LEVEL FLOW SHOULD TURN
AROUND TO THE EAST AND EVENTUALLY SOUTHEAST LATE THURSDAY NIGHT
INTO FRIDAY. HELD ON TO SOME LINGERING SLIGHT CHANCE POPS ACROSS
EASTERN ZONES WITH THE MOIST EAST FLOW AS ADVERTISED BY THE ECMWF
AND GFS. INSTABILITY APPEARS MEAGER...BUT WENT AHEAD AND MENTIONED
AN ISOLATED THUNDERSTORM OR TWO IN THE WORDED FORECASTS.
FOR FRIDAY...ANOTHER UPPER WAVE LOOKS TO MOVE EASTWARD OUT FROM
THE INTERMOUNTAIN WEST. THERE IS SOME WEAK LARGE SCALE ASCENT AS
EVIDENCED BY SOME UPPER LEVEL PV ACROSS THE NORTHERN AND
NORTHEASTERN ZONES. AS A RESULT...RETAINED INHERITED SLIGHT CHANCE
POPS ON FRIDAY. WITH THE RETURN TO THE SOUTH FLOW...EXPECT AN
INCREASE IN LOW LEVEL MOISTURE AND AN INCREASE IN THE
TEMPERATURES AS WELL. TEMPERATURES WILL CLIMB BACK TOWARDS
SEASONAL NORMS ON FRIDAY...OUTSIDE ANY PRECIPITATION THAT OCCURS.
&&
.LONG TERM (SATURDAY AND SUNDAY)...
FOR SATURDAY AND SUNDAY...MAINTAINED SLIGHT CHANCES FOR
PRECIPITATION ACROSS NORTHERN AND EASTERN ZONES WITH THESE AREAS
REMAINING ON THE NORTHERN AND EASTERN FRINGES OF A BUILDING MID
LEVEL RIDGE. HIGH TEMPERATURES SHOULD CLIMB INTO THE 90S AREA
WIDE ON SATURDAY. BOTH THE GFS AND ECMWF ADVERTISE A WEAK
BACKDOOR COLD FRONT SOMETIME LATE SUNDAY. THE RIDGE SHOULD
GRADUALLY WEAKEN ON ITS EASTERN PERIPHERY WHICH MAY ALLOW FOR THE
DEVELOPMENT OF SOME PRECIPITATION ALONG THE FRONT. AS A
RESULT...HAVE INTRODUCED LOW CHANCE POPS MAINLY ALONG THE RED
RIVER AND ACROSS EASTERN ZONES FOR SUNDAY AND INTO THE DAY ON
MONDAY. THERE ARE SOME DISCREPANCIES BETWEEN THE GFS AND THE ECMWF
IN THE LONG TERM WITH REGARDS TO HOW FAR SOUTH THIS NEXT COLD
FRONT WILL SWEEP SO CONFIDENCE IS NOT HIGH ENOUGH TO DEVIATE TOO
FAR FROM A CONSENSUS/BLENDED FORECAST.
BAIN
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 67 84 73 93 77 / 40 20 10 20 10
WACO, TX 69 83 74 94 76 / 30 30 20 10 5
PARIS, TX 63 79 64 89 73 / 40 20 20 30 30
DENTON, TX 63 82 69 93 76 / 40 10 10 20 20
MCKINNEY, TX 64 81 69 92 76 / 40 20 10 30 20
DALLAS, TX 68 85 74 94 78 / 40 20 10 20 10
TERRELL, TX 66 81 72 92 76 / 40 30 20 20 10
CORSICANA, TX 68 82 73 93 76 / 30 30 20 20 10
TEMPLE, TX 70 86 73 94 75 / 40 30 20 10 5
MINERAL WELLS, TX 64 83 70 94 75 / 40 20 10 20 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
66
AREA FORECAST DISCUSSION
NWS TUCSON AZ
405 AM MST THU AUG 20 2015
.SYNOPSIS...EXPECT ISOLATED TO SCATTERED THUNDERSTORMS MAINLY FROM
TUCSON EAST AND SOUTH THROUGH TONIGHT. INCREASING CHANCES FOR
SHOWERS AND THUNDERSTORMS WILL THEN BEGIN FRIDAY WITH THE BEST
CHANCE OF WIDESPREAD RAINFALL EARLY NEXT WEEK. THE INCREASED
MOISTURE WILL ALSO KEEP DAYTIME TEMPERATURES CLOSE TO SEASONAL
AVERAGES FRIDAY INTO EARLY NEXT WEEK.
&&
.DISCUSSION...IR SATELLITE IMAGERY AND SURFACE OBSERVATIONS
INDICATED CLEAR SKIES ACROSS MUCH OF SE ARIZONA AT THIS TIME. THE
EXCEPTION WAS SOME CIRRIFORM CLOUDINESS MAINLY ACROSS THE WHITE
MOUNTAINS...AND SOME MID-LEVEL CLOUDS NEAR THE INTERNATIONAL BORDER
ADJACENT SANTA CRUZ/COCHISE COUNTIES. CLOUD TOPS ASSOCIATED WITH A
CONVECTIVE COMPLEX OVER EAST CENTRAL SONORA HAVE BEEN WARMING DURING
THE PAST 1-2 HOURS. THIS SYSTEM LIKELY SENT AN OUTFLOW NWD...WITH
LIGHTNING DETECTED DURING THE PAST 60-90 MINUTES IN NERN SONORA SW
OF DOUGLAS.
BASED ON VARIOUS NWP SOLUTIONS...THERE WERE NO SIGNIFICANT
ADJUSTMENTS TO THE INHERITED GRIDDED DATA POP/WEATHER/TEMP FIELDS
FOR THIS FORECAST ISSUANCE. HIGH PRESSURE ALOFT CENTERED NEAR THE
NRN BAJA CALIFORNIA COAST WILL WEAKEN INTO THIS WEEKEND. THE DRY
NWLY FLOW GENERALLY IN THE 700-300MB LAYER WILL TRANSITION TO
LIGHT WLY FLOW FRI AND CONTINUE SAT.
FOR TODAY AND TONIGHT...SEVERAL HRRR SOLUTIONS SUGGEST AN EARLY
START TO SHOWER/TSTM ACTIVITY...PERHAPS BY 18Z-19Z SOUTH-TO-
SOUTHEAST OF TUCSON AND ESPECIALLY FAVORING SANTA CRUZ/SWRN COCHISE
COUNTIES BY MID-AFTERNOON. MEANWHILE...THERE SHOULD BE ENOUGH
MOISTURE TO JUSTIFY ISOLATED SHOWERS/TSTMS THIS AFTERNOON INTO
TONIGHT FROM TUCSON EAST TO THE NEW MEXICO BORDER. PRECIP-FREE
CONDITIONS WILL CONTINUE ACROSS WRN PIMA COUNTY.
20/00Z GFS/ECMWF/CMC SUGGEST THAT PRECIP COVERAGE SHOULD INCREASE
STARTING FRI FOLLOWED BY SCATTERED TO PERHAPS NUMEROUS SHOWERS/
TSTMS...ESPECIALLY SUN INTO MON NIGHT OR SO. THIS SCENARIO SEEMS
REASONABLE GIVEN THAT THE MID AND UPPER FLOW IS PROGGED TO BECOME
ELY/SELY STARTING SUN AND CONTINUING EARLY NEXT WEEK. HAVE NOTED
SOME DISCREPANCIES BETWEEN THE GFS/ECMWF SOLUTIONS FOR EARLY NEXT
WEEK. IN GENERAL...THE 20/00Z GFS TRENDED SOMEWHAT DRIER VERSUS
PREVIOUS GFS SOLUTIONS FOR QPF/S SUN-MON...AND THE 20/00Z ECMWF WAS
MARKEDLY MORE ROBUST WITH QPF/S FOR MON-TUE VERSUS THE 20/00Z GFS.
BASED ON THESE DIFFERENCES...OPTED TO MAKE ONLY VERY MINOR
MODIFICATIONS TO THE GRIDDED DATA POPS SUN-TUE. AT THIS TIME...
APPEARS THAT THE BEST COVERAGE OF SHOWERS/TSTMS SHOULD OCCUR ROUGHLY
SUN AFTERNOON INTO MON NIGHT...OR PERHAPS EARLY TUE. THEREAFTER...
THE GFS TRANSITIONED THE UPPER HIGH CENTER FROM NEAR THE FOUR
CORNERS REGION INTO SERN NEW MEXICO/WEST TEXAS NEXT WED. SWLY FLOW
ALOFT ASSOCIATED WITH THIS SCENARIO WOULD CONFINE SHOWERS/TSTMS
MAINLY TO ERN SECTIONS BY NEXT WED. HOWEVER...THE ECMWF MAINTAINED
THE UPPER HIGH TO BE CENTERED NEAR THE FOUR CORNERS. SLY/SELY FLOW
ALOFT ASSOCIATED WITH THIS SCENARIO WOULD KEEP PRECIP CHANCES HIGHER
FURTHER WWD VERSUS THE GFS SOLUTION. THE UPSHOT...ISOLATED TO
SCATTERED SHOWERS/TSTMS AREA-WIDE NEXT WED...WITH HIGHER POPS ACROSS
GREENLEE/GRAHAM/COCHISE COUNTIES.
HIGH TEMPS TODAY WILL BE QUITE SIMILAR TO TEMPS ACHIEVED WED...
AND WILL CONTINUE TO AVERAGE ABOUT 2-5 DEGS F ABOVE NORMAL. SOME
MINOR COOLING WILL THEN OCCUR FRI FOLLOWED BY NEAR NORMAL DAYTIME
TEMPS FOR MUCH OF THE AREA SAT-TUE. HIGH TEMPS SHOULD TREND UPWARD
AND GENERALLY A FEW DEGS ABOVE NORMAL NEXT WED.
&&
.AVIATION...VALID THRU 21/06Z.
FEW-SCT CLOUDS ABV 12K FT. AFT 20/21Z SCT TO LOCALLY BKN 8-10K FT
AND SCT-BKN LYRS AOA 12K FT. CHANCE FOR -SHRA/-TSRA FROM KTUS SOUTH
AND EAST...WITH AN EMPHASIS ON THE SOUTHERN TERMINALS KOLS AND KDUG.
BRIEF MVFR CONDITIONS AND GUSTY WINDS MAY BE POSSIBLE NEAR STRONGER
TSRA. OTHERWISE...WINDS WILL GENERALLY BE LIGHT AND TERRAIN DRIVEN
UNDER 10 KTS EXCEPT WLY 6-13KTS 20/21Z THRU 21/03Z. AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...MOISTURE WILL START TO INCREASE TODAY WITH ISOLATED
SHOWERS AND THUNDERSTORMS POSSIBLE...MAINLY SOUTHERN AREAS. THEN
THE MOISTURE AND THUNDERSTORMS CHANCES WILL INCREASE AND SPREAD
THROUGHOUT SOUTHEAST ARIZONA THROUGH THE WEEKEND INTO EARLY NEXT
WEEK. WINDS WILL BE TYPICAL FOR MID AUGUST AND GENERALLY LESS THAN
15 MPH THEN THE WIND WILL BECOME EASTERLY MONDAY AND TUESDAY...BUT
AGAIN GENERALLY REMAINING 15 MPH OR LESS.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
DISCUSSION...FRANCIS
AVIATION/FIRE WEATHER...CERNIGLIA
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1038 AM EDT THU AUG 20 2015
.SYNOPSIS...
DEEP MOISTURE WILL REMAIN IN THE FORECAST AREA THROUGH FRIDAY.
A WEAK FRONT APPROACHING FROM THE NORTHWEST WILL MOVE INTO THE
AREA TONIGHT AND REMAIN NEAR THE REGION DURING THE REST OF THE
WEEKEND. THERE WILL BE A CONTINUED CHANCE OF SHOWERS AND
THUNDERSTORMS.
&&
.NEAR TERM /THROUGH TONIGHT/...
THIS MORNING/S ANALYSIS SHOWED A COLD FRONT ALONG THE MOUNTAINS. A
PREFRONTAL TROUGH EXTENDED THROUGH WESTERN SOUTH CAROLINA
SOUTHWARD INTO EASTERN GEORGIA. A TONGUE OF HIGHER DEW POINT
TEMPERATURES EXTENDED FROM COASTAL GEORGIA NORTHWESTWARD INTO THE
CENTRAL SAVANNAH RIVER AREA. THE HRRR DISPLAYED DEVELOPMENT FIRST
IN THIS AREA EARLY THIS AFTERNOON WHICH APPEARS REASONABLE BECAUSE
OF CONVERGENCE INTO THE PREFRONTAL TROUGH AND HIGHER MOISTURE.
THIS MORNING/S WATER VAPOR IMAGERY SHOWED SOME MID-LEVEL DRYING
INDICATED WE MAY REMAIN BETWEEN GREATER UPPER-LEVEL LIFT THIS
AFTERNOON. FORECASTED CHANCE POPS NORTH TO LIKELY IN THE CSRA THIS
AFTERNOON. THE SPC WRF DISPLAYED CONSIDERABLE COVERAGE OF SHOWERS
AND THUNDERSTORMS TONIGHT WHICH MAY BE CORRECT BECAUSE OF
CONVERGENCE ASSOCIATED WITH THE WEAK FRONT MOVING INTO THE AREA
AND SOME UPPER-LEVEL LIFT AHEAD OF THE NEXT SHORTWAVE TROUGH.
THE MAIN FORECAST PROBLEM THROUGH TONIGHT IS THE THREAT OF HEAVY
RAIN BECAUSE OF PRECIPITABLE WATER NEAR 2 INCHES AND POSSIBLE
TRAINING. THERE IS LESS OF A DAMAGING WIND THREAT WITH A FORECAST
SOUNDING CLOSE TO MOIST ADIABATIC.
USED THE GUIDANCE CONSENSUS FOR THE HIGH TEMPERATURE FORECAST
TODAY. THE HIGH MOISTURE FAVORED THE WARMER TEMPERATURE GUIDANCE
TONIGHT.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
BELIEVE THE DIFFUSE FRONT WILL REMAIN STALLED NEAR THE
FORECAST AREA. MOISTURE MAY BECOME MORE SHALLOW...ESPECIALLY IN
THE NORTH. THE NAM INDICATED LESS DRYING COMPARED TO THE GFS. THE
PATTERN FAVORS THE SLOWER TIMING AND WE LEANED TOWARD THE HIGHER
MOS POPS. PRECIPITABLE WATER REMAINING NEAR 2 INCHES INDICATES A
CONTINUED THREAT OF THUNDERSTORMS WITH LOCALLY HEAVY RAIN. USED
THE GUIDANCE CONSENSUS FOR THE HIGH TEMPERATURE FORECAST AND
WARMER GUIDANCE FOR THE LOW TEMPERATURE BECAUSE OF THE RECENT BIAS
AND MOIST AIR MASS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
MOISTURE ASSOCIATED WITH THE REMNANTS OF THE FRONT SHOULD
CONTINUE THROUGH SUNDAY. THE GFS AND ECMWF DISPLAY ANOTHER FRONT
MOVING INTO THE AREA MONDAY WITH THIS FEATURE LINGERING NEAR THE
AREA DURING THE REST OF THE MEDIUM-RANGE PERIOD. HOWEVER...DEEPER
MOISTURE APPEARS TO REMAIN EAST OF THE FORECAST AREA AHEAD OF THE
UPPER TROUGH. THE GFS...ECMWF...AND EKD MOS HAVE POPS OF 20 TO 30
PERCENT THROUGH THE PERIOD.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
MAINLY VFR CONDITIONS EXPECTED FOR MUCH OF THE PERIOD...WITH LOW
CONFIDENCE IN RESTRICTIONS IN AFTERNOON AND EVENING CONVECTION.
MAIN CONCERN TODAY IS POTENTIAL FOR AFTERNOON CONVECTION...WITH
FRONTAL BOUNDARY APPROACHING FROM THE NORTHWEST CONVECTION WILL BE
POSSIBLE THIS AFTERNOON AND EVENING. CONFIDENCE IN TIMING AND
COVERAGE REMAINS TOO LOW TO INCLUDE IN TAFS. CONVECTION WILL
DIMINISH WITH SUNSET AND THE FRONTAL BOUNDARY CROSSING THE TAF
SITES OVERNIGHT. WINDS WILL BE OUT OF THE WEST-SOUTHWEST TODAY AT
5 TO 10 KNOTS AND WILL ROTATE TO NORTHERLY OVERNIGHT AS THE FRONT
MOVES INTO THE AREA.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE FRIDAY MORNING
IN FOG AND/OR STRATUS...AND SCATTERED MAINLY AFTERNOON AND
EVENING THUNDERSTORMS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
99
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
928 AM EDT THU AUG 20 2015
.SYNOPSIS...
DEEP MOISTURE WILL REMAIN IN THE FORECAST AREA THROUGH FRIDAY.
A WEAK FRONT APPROACHING FROM THE NORTHWEST WILL MOVE INTO THE
AREA TONIGHT AND REMAIN NEAR THE REGION DURING THE REST OF THE
WEEKEND. THERE WILL BE A CONTINUED CHANCE OF SHOWERS AND
THUNDERSTORMS.
&&
.NEAR TERM /THROUGH TONIGHT/...
THIS MORNING/S ANALYSIS SHOWED A COLD FRONT ALONG THE MOUNTAINS. A
PREFRONTAL TROUGH EXTENDED THROUGH WESTERN SOUTH CAROLINA
SOUTHWARD INTO EASTERN GEORGIA. A TONGUE OF HIGHER DEW POINT
TEMPERATURES EXTENDED FROM COASTAL GEORGIA NORTHWESTWARD INTO THE
CENTRAL SAVANNAH RIVER AREA. THE HRRR DISPLAYED DEVELOPMENT FIRST
IN THIS AREA EARLY THIS AFTERNOON WHICH APPEARS REASONABLE BECAUSE
OF CONVERGENCE INTO THE PREFRONTAL TROUGH AND HIGHER MOISTURE.
THIS MORNING/S WATER VAPOR IMAGERY SHOWED SOME MID-LEVEL DRYING
INDICATED WE MAY REMAIN BETWEEN GREATER UPPER-LEVEL LIFT THIS
AFTERNOON. FORECASTED CHANCE POPS NORTH TO LIKELY IN THE CSRA THIS
AFTERNOON. THE SPC WRF DISPLAYED CONSIDERABLE COVERAGE OF SHOWERS
AND THUNDERSTORMS TONIGHT WHICH MAY BE CORRECT BECAUSE OF
CONVERGENCE ASSOCIATED WITH THE WEAK FRONT MOVING INTO THE AREA
AND SOME UPPER-LEVEL LIFT AHEAD OF THE NEXT SHORTWAVE TROUGH.
THE MAIN FORECAST PROBLEM THROUGH TONIGHT IS THE THREAT OF HEAVY
RAIN BECAUSE OF PRECIPITABLE WATER NEAR 2 INCHES AND POSSIBLE
TRAINING. THERE IS LESS OF A DAMAGING WIND THREAT WITH A FORECAST
SOUNDING CLOSE TO MOIST ADIABATIC.
USED THE GUIDANCE CONSENSUS FOR THE HIGH TEMPERATURE FORECAST
TODAY. THE HIGH MOISTURE FAVORED THE WARMER TEMPERATURE GUIDANCE
TONIGHT.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
BELIEVE THE DIFFUSE FRONT WILL REMAIN STALLED NEAR THE
FORECAST AREA. MOISTURE MAY BECOME MORE SHALLOW...ESPECIALLY IN
THE NORTH. THE NAM INDICATED LESS DRYING COMPARED TO THE GFS. THE
PATTERN FAVORS THE SLOWER TIMING AND WE LEANED TOWARD THE HIGHER
MOS POPS. PRECIPITABLE WATER REMAINING NEAR 2 INCHES INDICATES A
CONTINUED THREAT OF THUNDERSTORMS WITH LOCALLY HEAVY RAIN. USED
THE GUIDANCE CONSENSUS FOR THE HIGH TEMPERATURE FORECAST AND
WARMER GUIDANCE FOR THE LOW TEMPERATURE BECAUSE OF THE RECENT BIAS
AND MOIST AIR MASS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
MOISTURE ASSOCIATED WITH THE REMNANTS OF THE FRONT SHOULD
CONTINUE THROUGH SUNDAY. THE GFS AND ECMWF DISPLAY ANOTHER FRONT
MOVING INTO THE AREA MONDAY WITH THIS FEATURE LINGERING NEAR THE
AREA DURING THE REST OF THE MEDIUM-RANGE PERIOD. HOWEVER...DEEPER
MOISTURE APPEARS TO REMAIN EAST OF THE FORECAST AREA AHEAD OF THE
UPPER TROUGH. THE GFS...ECMWF...AND EKD MOS HAVE POPS OF 20 TO 30
PERCENT THROUGH THE PERIOD.
&&
.AVIATION /13Z THURSDAY THROUGH MONDAY/...
MAINLY VFR CONDITIONS EXPECTED FOR MUCH OF THE PERIOD...WITH LOW
CONFIDENCE IN RESTRICTION IN AFTERNOON AND EVENING CONVECTION.
MID CLOUDS HAVE PERSISTED OVERNIGHT RESULTING IN LESS FOG AND
STRATUS FORMATION THIS MORNING. NEXT CONCERN WILL BE POTENTIAL FOR
AFTERNOON CONVECTION...WITH FRONTAL BOUNDARY APPROACHING FROM THE
NORTHWEST CONVECTION WILL BE POSSIBLE THIS AFTERNOON AND EVENING.
CONFIDENCE IN TIMING AND COVERAGE REMAINS TOO LOW TO INCLUDE IN
TAFS. CONVECTION WILL DIMINISH WITH SUNSET AND THE FRONTAL
BOUNDARY CROSSING THE TAF SITES OVERNIGHT.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE FRIDAY MORNING
IN FOG AND/OR STRATUS...AND SCATTERED MAINLY AFTERNOON AND
EVENING THUNDERSTORMS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
99
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1030 AM EDT THU AUG 20 2015
.SYNOPSIS...
A STRONG AND SLOW MOVING COLD FRONT WILL CROSS THE AREA TODAY WHICH
WILL BRING SHOWERS AND THUNDERSTORMS WITH HEAVY RAIN AND POSSIBLY
GUSTY WINDS. COOLER AND DRIER AIR WILL RETURN BEHIND THE COLD FRONT
BRINGING SEASONABLE AND PLEASANT WEATHER FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AT 1000 AM... A LINE OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED
ALONG OF THE FRONT ACROSS NORTHWESTERN PENNSYLVANIA NORTHWARD TO
SOUTHERN ONTARIO AND IS HEADING TOWARD WESTERN NEW YORK. THIS IS
FEATURE IS WELL CAPTURED BY THE HRRR AND IS FORECAST TO MOVE ACROSS
THE NIAGARA FRONTIER AND WESTERN NEW YORK THROUGH MIDDAY AND THE
AFTERNOON.
WITH THE RISK OF HEAVY RAIN...THE THREAT FOR FLASH FLOODING
CONTINUES ACROSS THE AREA. PWATS FROM 00Z SOUNDINGS AT DTX/ILN RUN
1.75 TO 2 INCHES...WITH A 35KT 850MB FLOW SET TO ADVECT THIS WARM
AND MOIST AIRMASS INTO OUR REGION TODAY. THE TIMING OF THE FRONTAL
PASSAGE IS ALSO FAVORABLE SINCE IT WILL ALLOW FOR DESTABILIZATION
FROM DAYTIME HEATING AHEAD OF THE FRONT...ESPECIALLY IN EASTERN
PORTIONS OF THE CWA. 00Z RUNS OF THE NAM/RGEM/GFS CAPTURE THESE
TRENDS WITH FORECAST WIND FIELDS SUGGESTING THE POTENTIAL FOR
TRAINING CELLS. THE AREA OF GREATEST CONCERN IS EASTERN PORTIONS OF
THE CWA WHERE THERE WILL BE MORE TIME FOR THE ATMOSPHERE TO
DESTABILIZE AND WHERE STORMS MAY DEVELOP ACROSS SOUTH-CENTRAL NEW
YORK AND INTERSECT THE SLOW MOVING FRONT EAST OR SOUTHEAST OF LAKE
ONTARIO. A CONSENSUS OF HIGH RESOLUTION GUIDANCE (4KM OR LESS) KEYS
ON THIS AREA...AND OTHER GUIDANCE SEEMS TO SUPPORT THIS IDEA. THERE
STILL IS A POTENTIAL FOR FLASH FLOODING ELSEWHERE SO THE UPDATE WILL
KEEP THE FLASH FLOOD WATCH IN EFFECT...BUT FEEL THE AREA MOST LIKELY
TO SEE THE GREATEST RAINFALL EXTENDS FROM WAYNE TO LEWIS COUNTIES.
IT IS ALSO WORTH NOTING THAT FFG IS FAIRLY HIGH IN MANY AREAS AND
EXACTLY WHERE HEAVY RAIN FALLS WILL PLAY A ROLE IN WHERE FLASH
FLOODING OCCURS. URBAN AREAS AND AREAS WITH STEEP TERRAIN TEND TO BE
MOST VULNERABLE.
A SECONDARY CONCERN IS TODAY IS THE POTENTIAL FOR SEVERE WEATHER.
FORECAST WIND PROFILES SUGGEST A FAIR AMOUNT OF WIND SHEAR AHEAD OF
THE FRONT...PRIMARILY UNIDIRECTIONAL SPEED SHEAR BELOW 850MB. CAPE
WILL BE LIMITED...GENERALLY ONLY 500 J/KG...BUT SOUNDINGS ARE VERY
MOIST WITH A TALL AND SKINNY CAPE. THIS MAY PRODUCE SOME STRONGER
STORMS WITH WINDS THE PRIMARY THREAT. LCLS WILL BE LOW AND
DIRECTIONAL SHEAR MAY BE LOCALLY ENHANCED NEAR EASTERN LAKE ONTARIO
SO EVEN AN ISOLATED TORNADO CANNOT BE RULED OUT IF STRONGER STORMS
DO DEVELOP.
OTHERWISE...THE FORECAST WILL USE CONSENSUS TIMING WITH HIGH
CONFIDENCE IN MEASURABLE PRECIPITATION DUE TO THE FOCUS PROVIDED
BY THE FRONTAL BOUNDARY. SHOWERS AND THUNDERSTORMS WILL LINGER
EAST OF LAKE ONTARIO INTO THE EVENING HOURS. TEMPERATURES WILL BE
ABOVE NORMAL AGAIN TODAY...ESPECIALLY IN EASTERN PORTIONS OF THE
CWA DUE THE THE LATER FROPA IN THESE AREAS.
MUCH COOLER AIR WILL MOVE INTO THE REGION TONIGHT WITH TEMPERATURES
FALLING INTO THE MID 50S TO LOWER 60S BY DAYBREAK. THE COMBINATION
OF A SHORTWAVE AND COOLER TEMPERATURES ALOFT MAY BE JUST ENOUGH
FOR SOME LAKE ENHANCED CLOUDS OR SHOWERS E AND NE OF THE LAKES
LATE TONIGHT. OTHERWISE...EXPECT CLEARING SKIES BEHIND THE FRONT
WITH SOME PATCHY RADIATION FOG POSSIBLE WHERE WINDS DROP OFF.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
NO CHANGES TO CURRENT FORECAST. PREVIOUS DISCUSSION...
HIGH PRESSURE WILL DOMINATE THE FORECAST INTO THIS WEEKEND WITH DRY
WEATHER AND CONSIDERABLY MORE COMFORTABLE TEMPERATURES AND HUMIDITY
LEVELS ACROSS WESTERN AND CENTRAL NEW YORK. MODELS SHOW THIS SURFACE
HIGH QUICKLY BUILDING IN BEHIND THE COLD FRONT DEPARTING ACROSS NEW
ENGLAND ON FRIDAY. THE ONLY EXCEPTION TO THE DRY CONDITIONS MAY BE
FRIDAY MORNING ON THE IMMEDIATE HEELS OF THE COLD FRONT WITH A
CHANCE FOR SOME LIMITED LAKE EFFECT SHOWERS EAST OF LAKES ERIE AND
ONTARIO. 850MB TEMPERATURES ACROSS THE LAKES ARE FORECAST TO DIP
BRIEFLY DOWN TO OR SLIGHTLY BELOW +8 TO +10C WHICH WOULD SUPPORT SOME
LAKE INDUCED INSTABILITY. MOISTURE IS FORECAST TO BE VERY LIMITED
WITH SOUNDINGS SHOWING VERY DRY AIR ABOVE 5KFT. THERE MAY BE ONLY
ENOUGH MOISTURE FOR LAKE EFFECT CLOUDS EAST OF THE LAKES WITH
SCATTERED DIURNAL CUMULUS DEVELOPING WELL INLAND OF THE LAKES.
THE ARRIVAL OF COOLER AIR ALOFT BEHIND THE COLD FRONT WILL KEEP HIGH
TEMPERATURES LIMITED TO THE LOW TO MID 70S FRIDAY THEN MID TO UPPER
70S SATURDAY AS 850MB TEMPS CLIMB BACK ABOVE +12C. DEWPOINTS IN THE
UPPER 40S TO LOW 50S WILL PROVIDE COMFORTABLE HUMIDITY LEVELS WITH
OVERNIGHT LOWS ALSO DIPPING INTO THE 50S EACH NIGHT WITH UPPER 40S
POSSIBLE ACROSS THE INTERIOR SOUTHERN TIER.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
WHILE FAIR AND DRY WEATHER IS EXPECTED TO LINGER INTO
SUNDAY...FORECAST MODELS INCLUDING THE GEFS ENSEMBLES SHOW A
SLIGHTLY ANOMALOUS 500MB TROUGH DIPPING ACROSS THE GREAT LAKES
REGION EARLY NEXT WEEK. THIS TROUGH LOOKS TO BE LED IN BY A WEAK
COLD FRONT CROSSING NEW YORK MONDAY FOLLOWED BY SEASONABLY COOL
TEMPERATURES TUESDAY AND WEDNESDAY.
A CHANCE OF SHOWERS AND THUNDERSTORMS HAS BEEN FEATURED ALONG THIS
FRONT MONDAY THEN SOME LAKE EFFECT SHOWERS MAY AGAIN BECOME POSSIBLE
MONDAY NIGHT AS 850MB TEMPERATURES DIP BACK INTO THE THE SINGLE
DIGITS OVER THE VERY WARM LAKES. HIGH TEMPERATURES IN THE MID 70S TO
AROUND 80 ON SUNDAY AND MONDAY LOOK TO BE FOLLOWED BY HIGHS CLOSER
TO 70 TUESDAY AND WEDNESDAY. THE 00Z GFS SHOWS SOME SHOWERS MAY BE
POSSIBLE IN THE COOL UNSTABLE AIRMASS TUESDAY BUT HAVE LEFT POPS
AT SLIGHT CHANCE FOR NOW AS THE 00Z ECMWF IS DRIER.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
CONDITIONS WILL DETERIORATE TODAY AS A STRONG UPPER LEVEL TROUGH
AND ASSOCIATED COLD FRONT APPROACHES THE AREA WITH SHOWERS AND
THUNDERSTORMS DEVELOPING AHEAD OF THE FRONT. SHOWERS AND
THUNDERSTORMS SHOULD BE SCATTERED IN NATURE WELL AHEAD OF THE
FRONT...BUT THERE SHOULD BE SOLID LINE THAT MOVES THROUGH LATE
THIS MORNING THROUGH THIS EVENING WHICH WILL PRODUCE PERIODS OF
MVFR/IFR CONDITIONS WHICH WILL SPREAD FROM WEST TO EAST THROUGH
TODAY.
CONDITIONS SHOULD IMPROVE RATHER QUICKLY BEHIND THE FRONT THIS
EVENING...HOWEVER SOME PATCHY IFR FOG IS POSSIBLE IN SOME SPOTS
LATE TONIGHT...WITH THE GREATEST POTENTIAL FOR THIS IN VALLEY
LOCATIONS SUCH AS JHW.
OUTLOOK...
FRIDAY THROUGH SUNDAY...VFR.
MONDAY...VFR WITH SCATTERED SHOWERS AND THUNDERSTORMS.
&&
.MARINE...
SOUTHERLY WINDS WILL PICK UP IN ADVANCE OF A COLD FRONT THROUGH THIS
MORNING...AND THEN WINDS WILL SHIFT TO THE SOUTHWEST BEHIND THE
FRONT THIS AFTERNOON AND EVENING. COOLER AIR BEHIND THE FRONT
SHOULD ENHANCE MIXING WITH AIR TEMPERATURES FORECAST TO DROP BELOW
THE LAKE TEMPERATURES. THIS WILL REQUIRE SMALL CRAFT ADVISORIES
FOR MOST OF THE WATERS...PRIMARILY FOR WINDS PRE- FRONTAL...AND
FOR WINDS AND WAVE ACTION BEHIND THE FRONT. THERE WILL ALSO BE
SHOWERS AND THUNDERSTORMS WITH THE FRONT WHICH MAY PRODUCE LOCALLY
HIGHER WINDS/WAVES.
LOOK FOR WINDS AND WAVES TO SUBSIDE FRIDAY AS HIGH PRESSURE MOVES
ACROSS THE LAKES IN THE WAKE OF THE FRONT WITH TRANQUIL WEATHER
LASTING THROUGH THE WEEKEND BEFORE A WEAKER FRONT CROSSES THE REGION
MONDAY.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...FLASH FLOOD WATCH FROM 2 PM EDT THIS AFTERNOON THROUGH LATE
TONIGHT FOR NYZ006>008.
FLASH FLOOD WATCH THROUGH THIS EVENING FOR NYZ001>005-010>014-
019>021-085.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT FRIDAY FOR LEZ040-041.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
LEZ020.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
LOZ042>045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL/WCH
SHORT TERM...FRANKLIN/SMITH
LONG TERM...SMITH
AVIATION...APFFEL
MARINE...APFFEL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1017 AM EDT THU AUG 20 2015
.SYNOPSIS...
A COLD FRONT WILL MOVE SLOWLY ACROSS THE AREA TONIGHT INTO FRIDAY
CONTINUING A GOOD CHANCE FOR THUNDERSTORMS. SUNNY AND SEASONABLE
WEATHER IS EXPECTED FOR THE WEEKEND BEHIND THIS FRONT. WARMER AND
MORE HUMID AIR WILL RETURN NEXT WEEK AHEAD OF A COLD FRONT WHICH
WILL APPROACH ON TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM THURSDAY...12Z CHS SOUNDING SHOULD BE REPRESENTATIVE
OF THE AIRMASS TODAY. MODIFIED FOR HEATING...EXPECT LI TO -4C AND
MLCAPE TO 1400 J/KG. PRECIPITABLE WATER JUST OVER 2 INCHES WILL
COMBINE WITH DESTABILIZATION THIS AFTERNOON TO PRODUCE AN
ENVIRONMENT SUPPORTIVE OF CONVECTION WITH THE POTENTIAL FOR
LOCALLY HEAVY DOWNPOURS. EXTENSIVE MORNING CLOUD COVER WILL LIMIT
THE RATE OF DESTABILIZATION AND COULD RESULT IN LESS COVERAGE THAN
THE CURRENT FORECAST INDICATES. LATEST HRRR DOES HINT AT THIS
AS WELL. MAY TWEAK THE POPS A BIT AND KEEP THE ENTIRE CWA IN THE
40-50 PERCENT RANGE...BUT WILL ALSO HAVE TO WATCH A WEAKENING 500
MB SHORTWAVE MOVING ACROSS UPSTATE SC THIS MORNING WHICH MAY
ENHANCE THE COVERAGE DURING THE AFTERNOON.
SCATTERED SHOWERS AND STORMS MAY LINGER THROUGH THE EVENING HOURS AS
THE COLD FRONT ENTERS THE EASTERN CAROLINAS. COOLING AT THE SURFACE
PLUS WARMING TEMPERATURES ALOFT SHOULD CAP OFF THE ATMOSPHERE TO
CONVECTION BY LATE EVENING WITH ONLY AN ISOLATED SHOWER OR TWO
POSSIBLE AFTER MIDNIGHT NEAR THE COAST. COMPARED TO MODEL SOLUTIONS
A FEW DAYS AGO THIS NOW LOOKS LIKE A CLEAN FRONTAL PASSAGE WITH
NORTHERLY SURFACE WINDS DEVELOPING OVERNIGHT ALL THE WAY DOWN TO THE
BEACHES.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...COLD FRONT WILL WAVER NEAR THE CWA ON
FRIDAY BEFORE WEAKENING WELL SOUTH ON SATURDAY. THIS CREATES AN
UNSETTLED FRIDAY...BUT VERY NICE WEATHER FOR THE WEEKEND.
WEAK SHORTWAVE RIDGING OVERHEAD TO START THE PERIOD WILL INHIBIT
RAPID PROGRESSION OF A COLD FRONT WHICH WILL BE NEAR THE COAST
FRIDAY MORNING. WHILE MID-LEVEL RIDGING WILL WEAKEN THROUGH THE
DAY...THIS FLOW ALOFT WILL IMPEDE THE FRONT ENOUGH THAT IT WILL
REMAIN DRAPED IN THE VICINITY...SLOWING EVEN FURTHER AS IT
COMBINES WITH THE EXPECTED SEA BREEZE DURING THE AFTN. THIS HYBRID
FRONT/SEA BREEZE WILL SERVE AS A FOCUS FOR CONVECTION FRIDAY
AFTN/EVE...AND SREF PROBS RISE ABOVE 90% FOR 6-HR PRECIP TOTALS
ABOVE 0.01 INCHES ACROSS THE EASTERN THIRD OF THE CWA. WILL RAMP
POP UPWARDS TO HIGH- CHC FOR THE COASTAL COUNTIES AND A BIT INLAND
FROM THERE...BUT MAINTAIN JUST SCHC/VERY LOW CHC WELL INLAND WHERE
DRIER AIR WILL BE WORKING IN BEHIND THE FRONT. LATE FRIDAY AND
INTO FRIDAY NIGHT AS THE SEA BREEZE WEAKENS AND THE MID-LEVEL
RIDGE DISSIPATES...THE FRONT WILL MAKE ITS FINAL PUSH AND BE
ALIGNED NE TO SW BUT SOUTH OF THE CWA BY SATURDAY MORNING. THIS
WILL LEAVE COOLER AND MUCH DRIER AIR IN PLACE SATURDAY...WITH
PWATS FALLING TO AROUND 1.25 INCHES AT THE END OF THE PERIOD. WILL
MAINTAIN JUST A VERY SCHC FOR SHOWERS FAR SE ZONES...ESPECIALLY THE
FIRST HALF OF THE DAY...BUT OTRW EXPECT A DRY AND PLEASANT
SATURDAY.
TEMPS BOTH AFTNS WILL BE SIMILAR THANKS TO THE LACK OF COOL
ADVECTION ASSOCIATED WITH THE FRONT. HIGHS FRIDAY WILL RANGE FROM
AROUND 88 AT THE COAST TO 92 WELL INLAND...AND JUST A DEGREE OR SO
COOLER ON SATURDAY. LOWS BOTH NIGHTS WILL DROP TO NEAR SEASONABLE
LEVELS...A DEGREE OR TWO EITHER SIDE OF 70...ALTHOUGH SATURDAY NIGHT
WILL BE THE COOLER OF THE TWO.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...ATYPICAL LATE AUGUST WEATHER TO START THE
PERIOD...BUT FOR THE BETTER...AS BRIGHT SUNSHINE WILL COMBINE WITH
LOW HUMIDITY TO MAKE SUNDAY A BEAUTIFUL DAY ACROSS THE AREA WITH
TEMPS NEAR SEASONABLE NORMS. BY MONDAY...RETURN FLOW WILL REDEVELOP
LOCALLY AS HIGH PRESSURE SPINS OFFSHORE AND A COLD FRONT APPROACHES
FROM THE WEST. MONDAY WILL LIKELY FEATURE ABOVE CLIMO TEMPS BUT WITH
INCREASING HUMIDITY AND AT LEAST ISOLATED CONVECTION POTENTIAL. FOR
THE LATTER HALF OF THE EXTENDED...THAT COLD FRONT IS BEING DRIVEN
SOUTHWARD BY SOME VORT ENERGY ROTATING AROUND THE SOUTHERN PERIPHERY
OF AN ANOMALOUSLY STRONG UPPER LOW OVER SE CANADA...WILL LIKELY
STALL ACROSS THE AREA. THIS WILL CREATE A PERIOD OF UNSETTLED
WEATHER FOR TUE/WED WITH TEMPS AROUND CLIMO LEVELS FOR HIGHS...BUT
POTENTIALLY VERY WARM OVERNIGHT LOWS DUE TO CLOUD COVER.
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
AS OF 12Z...PATCHY AREAS OF MVFR THIS MORNING DUE TO FOG...WITH
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED
TODAY AND THIS EVENING AHEAD OF AN APPROACHING COLD FRONT.
LATEST RADAR IMAGERY REMAINS FAIRLY QUIET THIS MORNING WITH ISOLATED
PATCHES OF -DZ IN SOME LOCATIONS. OBSERVATIONS REPORT PATCHY AREAS
OF FOG WHICH ARE CREATING MVFR. EXPECT THESE CONDITIONS TO IMPROVE
OVER THE NEXT HOUR OR TWO. WILL SEE INCREASING SOUTH-SOUTHWEST WINDS
THROUGH THE MORNING HOURS...REACHING TO AOB 12 KTS BY THIS
AFTERNOON. ISOLATED TO SCATTERED SHRA/TSRA EXPECTED THROUGHOUT THE
DAY INTO THE EVENING HOURS AHEAD OF AN APPROACHING COLD
FRONT...INITIALIZING AT THE COAST LATE MORNING AND MOVING INLAND.
OVERNIGHT...ANY LINGERING ACTIVITY WILL TAPER OFF AND WINDS WILL
BECOME LIGHT AS THE COLD FRONT MOVES INTO THE FORECAST AREA.
LIGHT FOG IS POSSIBLE BEFORE DAYBREAK ON FRIDAY.
EXTENDED OUTLOOK...VFR WITH SCATTERED SHOWERS AND THUNDERSTORMS
THROUGH THE WEEKEND.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM THURSDAY...A WEAK RIDGE OF HIGH PRESSURE EAST OF
THE BAHAMAS WILL BREAK DOWN TODAY AS A COLD FRONT APPROACHES FROM
THE WEST. THIS FRONT IS BEING DRIVEN EASTWARD BY LOW PRESSURE NEAR
LAKE SUPERIOR. THE FRONT SHOULD REACH THE BEACHES OF NORTH AND
SOUTH CAROLINA AFTER MIDNIGHT TONIGHT...PASSING WELL OFF THE COAST
BEFORE DAYBREAK. COMPARED TO MODEL SOLUTIONS JUST A COUPLE DAYS
AGO THIS IS A MUCH CLEANER AND MORE DRAMATIC FRONTAL
PASSAGE...RATHER UNUSUAL FOR MID-AUGUST.
SOUTHWEST WINDS AROUND 10 KNOTS TODAY WILL INCREASE TO 10-15 KT THIS
EVENING...BUT SHOULD VEER NORTHERLY AFTER MIDNIGHT AS THE FRONT
PUSHES THROUGH.
UNTIL THE FRONT ARRIVES...A WARM AND HUMID AIRMASS SHOULD GENERATE
SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AT THE COAST.
STEERING WINDS ARE FROM THE WEST...MEANING THESE STORMS WILL GET
BLOWN OUT PAST THE BEACHES AND SHOULD AFFECT THE NEARSHORE WATERS.
REDUCED VISIBILITY IN HEAVY RAINFALL...GUSTY WINDS...AND FREQUENT
LIGHTNING ARE ALL EXPECTED THIS AFTERNOON WITH THESE STORMS.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...COLD FRONT WILL BE NEAR THE COAST MUCH OF
FRIDAY AS IT WAVERS IN THE VICINITY THANKS TO MID-LEVEL RIDGING AND
WEAK STEERING FLOW. WITH THIS FRONT NEAR THE COASTAL WATERS ALL
DAY...WINDS WILL BE LIGHT BUT FEATURE A VARIETY OF DIRECTIONS...AND
THUS THE WAVE SPECTRUM WILL BE COMPRISED OF MANY WAVE GROUPS WITH
LOW AMPLITUDE...CREATING SEAS OF 1-2 FT. FRIDAY NIGHT THIS FRONT
WILL FINALLY GET A PUSH SOUTH AS HIGH PRESSURE EXPANDS FROM THE
NORTHEAST...AND THIS WILL CREATE NE WINDS AROUND 10 KTS ACROSS THE
WATERS...PERSISTING THROUGH SATURDAY. THIS MORE PRONOUNCED WIND
DIRECTION ALONG WITH HIGHER SPEEDS WILL DRIVE WAVE HEIGHTS SLIGHTLY
HIGHER...REACHING 1-3 FT FRIDAY NIGHT THROUGH SATURDAY NIGHT WITH A
NE WIND WAVE BECOMING PREDOMINANT.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 300 AM THURSDAY...LIGHT NORTH WINDS SUNDAY WILL GRADUALLY VEER
TO THE SW BY MONDAY AS RETURN FLOW REDEVELOPS LOCALLY. SPEEDS SUNDAY
WILL BE LESS THAN 10 KTS...BUT MAY INCREASE TO 10-15 KTS DURING
MONDAY AS THE GRADIENT TIGHTENS AHEAD OF A COLD FRONT APPROACHING
FROM THE NW. SEAS WILL BE NEARLY ENTIRELY WIND-WAVE DRIVEN THIS
PERIOD...RISING FROM 1-2 FT SUNDAY TO 2-3 FT MONDAY...ALTHOUGH SOME
LONG PERIOD BACK-SWELL ASSOCIATED WITH A LOW PRESSURE NEAR BERMUDA
MAY BEGIN TO ENTER THE SPECTRUM VERY LATE IN THE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...CRM/TRA
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...SGL
MARINE...TRA/JDW
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1047 AM EDT THU AUG 20 2015
.SYNOPSIS...
A WEAK COLD FRONT WILL APPROACH THE AREA FROM THE WEST TODAY
BRINGING INCREASED CHANCES FOR SHOWERS AND THUNDERSTORMS. IN THE
FRONTS WAKE...SOME DRYING IS EXPECTED OVER THE WEEKEND. ANOTHER WEAK
FRONT APPROACHES THE CAROLINAS ON MONDAY WITH HIGH PRESSURE MOVING
OVER THE REGION BEHIND THE FRONT.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1040 AM...SKIES CLEARING OUT FROM WEST TO EAST ACROSS THE
AREA. HOWEVER...CU BEGINNING TO DEVELOP IN THE CLEARED AREA AS
HEATING BEGINS. EXPECT THE CU TO CONTINUE TO INCREASE THRU THE DAY.
STILL LOOKS LIKE ANOTHER ROUND OF AT LEAST SCT CONVECTION TODAY
GIVEN THE UNSTABLE ATMOSPHERE AND THE COLD FRONT APPROACHING FROM
THE NW. OLDER CAM GUIDANCE WAS SUGGESTING POSSIBLY LESS COVERAGE
TODAY. HOWEVER...LATEST RUNS SHOW GOOD COVERAGE...BUT DO SUGGEST NE
GA AND THE UPSTATE MAY STILL HAVE LOWER COVERAGE THAN NC. WILL NOT
ADJUST POP FOR THE AFTERNOON...BUT DID SLOW DEVELOPMENT GIVEN THE
LACK OF CURRENT COVERAGE AND PREVIOUS QUICK ONSET. STILL EXPECT
MODERATE INSTABILITY WITH EFFECTIVE SHEAR APPROACHING MODERATE
LEVELS AS WELL. DCAPE WILL NOT BE EXCEPTIONALLY HIGH...BUT LOOKS TO
BE OVER 500 J/KG. THEREFORE...SEVERE STORMS POSSIBLE AGAIN. WITH PW
VALUES APPROACHING 2 INCHES...ISOLATED FLOODING WILL ALSO BE
POSSIBLE. HIGHS WILL BE TRICKY...ESPECIALLY GIVEN THE MORNING
CLEARING...BUT CURRENT VALUES SHUD BE CLOSE.
AS OF 630 AM THURSDAY...ONLY ISOLATED SHOWERS CONTINUE FOR THE
UPDATE...SO HAVE REDUCED POPS SIGNIFICANTLY THROUGH THE MORNING. AS
MENTIONED BELOW...HIRES GUIDANCE CONTINUES TO NOT BE VERY EXCITED
ABOUT CONVECTIVE POTENTIAL THIS AFTERNOON THOUGH SYNOPTIC MODELS
CONTINUE TO PAINT CONVECTIVE PRECIP ACROSS THE AREA. WITH THIS
UNCERTAINTY AND GIVEN PERSISTENCE TRENDS...MADE ONLY MINOR
ADJUSTMENTS TO AFTERNOON POPS.
AS OF 230 AM THURSDAY...BENIGN CONDITIONS AT AFD TIME...BUT THIS
AFTER QUITE AN EVENTFUL EVENING YESTERDAY. WARM RAIN PROCESSES AND
TRAINING CELLS RESULTED IN ANOTHER 5+ INCHES OF RAIN ACROSS PORTIONS
OF UNION COUNTY NC WHERE SOME SIGNIFICANT FLASH FLOODING WAS
REPORTED. GOOSE CREEK REMAINS HIGH WITH ONE POINT STILL IN FLOOD AT
AFD TIME.
ONTO THE FORECAST...DEEP UPPER TROUGH STRETCHING DOWN THE
MISSISSIPPI WILL BEGIN TO LIFT INTO THE GREAT LAKES AND SOUTHEAST
CANADA TODAY...WITH AN OCCLUDED COLD FRONT PUSHING TOWARD THE
SOUTHERN APPALACHIANS. THE SOUTHERN EDGE OF THE FRONT IS PROGGED TO
PUSH THROUGH THE FORECAST AREA TONIGHT BUT WASH OUT QUICKLY.
DEWPOINTS BY SUNRISE FRIDAY WILL ACTUALLY DROP INTO THE UPPER 60S
ACROSS THE UPSTATE WITH SOME UPPER 50S IN THE MOUNTAINS. WE WILL
ALSO SEE LOW TEMPERATURES A COUPLE OF DEGREES COOLER THAN WE HAVE
BEEN EXPERIENCING LATELY...BUT THE DECREASE IN DEWPOINTS WILL NOT BE
QUITE QUICK ENOUGH TO BRING LOWS DOWN TO SEASONAL NORMALS JUST YET.
ANOTHER WEAK SHORTWAVE DIVING TOWARD THE OHIO VALLEY TONIGHT...WITH
A FAIRLY POTENT VORT LOBE...WILL SERVE TO PULL UP ADDITIONAL
MOISTURE AS SURFACE PATTERN TRANSITIONS TO HIGH PRESSURE.
BIGGEST CONCERN OF THE NEAR TERM WILL BE CHANCE OF ADDITIONAL
CONVECTION TODAY. WITH THE APPROACH AND PASSAGE OF THE COLD FRONT...
CERTAINLY THERE IS ENOUGH SYNOPTIC FORCING...AND WITH PW VALUES
REMAINING GENERALLY AT OR ABOVE 2 INCHES...WE SHOULD CONTINUE TO SEE
FAIRLY EFFICIENT RAIN PRODUCERS. NOT GOOD NEWS FOR FOLKS THAT
EXPERIENCED SOME SIGNIFICANT RAINFALL AMOUNTS AND RESULTING FLASH
FLOODING LAST NIGHT. LUCKILY SBCAPE VALUES GENERALLY REMAIN BELOW
1000 J/KG SO CONVECTIVE INTENSITY SHOULD NOT BE QUITE AS BAD AS
YESTERDAY. ALL THAT SAID...HI-RES GUIDANCE NOT PARTICULARLY
IMPRESSED WITH CONVECTIVE POTENTIAL FOR THIS AFTERNOON. HRRR ONLY
HAS ISOLATED CONVECTION AT BEST EVEN THROUGH 20Z. WRF NMM AND ARW
REFLECTIVITY GUIDANCE ON PAR WITH THE HRRR. WITH THAT...KEPT POPS AT
CHANCE AT BEST ACROSS THE UPSTATE AND MOST OF THE NC PIEDMONT...WITH
LIKELIES IN THE MOUNTAINS. CONFIDENCE NOT PARTICULARLY HIGH SO WILL
HAVE TO MONITOR THROUGH THE DAY.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 310 AM EDT THURSDAY...THE SHORT TERM FCST PICKS UP AT 12Z ON
FRIDAY WITH THE UPPER TROF LIFTING NE OF THE GREAT LAKES AS HEIGHTS
BEGIN TO RISE OVER THE SE REGION. THIS PATTERN WILL PERSIST INTO THE
MEDIUM RANGE WITH VARIOUS LOBES OF SHORTWAVE ENERGY APPROACHING THE
CWFA FROM THE WEST OVER THE WEEKEND. IN ADDITION...ANOTHER COMPACT
UPPER TROF WILL DIG DOWN OVER THE US/CANADA BORDER OVER THE WEEKEND
AND MOVE ACROSS THE GREAT LAKES BY THE START OF THE MEDIUM RANGE.
ON FRIDAY...THE SFC HIGH GRADUALLY SLIDES EASTWARD AND THEN NE THRU
THE DAY AND EVENING WITH LOW LVL DRYING AS THE BNDY LAYER FLOW
BECOMES MORE NLY. THE GFS SOLUTION CONTINUES TO BE THE DRIEST MODEL
OVERALL WITH THE NAM BEING THE WETTEST. REGARDLESS OF MODEL
CHOICE...THE TREND IS FOR DRIER PROFILES AND LESS INFLUENCE FROM THE
GULF AS WE MOVE INTO SAT. ON SATURDAY...THE SFC HIGH SLIDES A BIT
FARTHER NE AND UP OVER NEW ENGLAND AS SOME WEAK WEDGING APPEARS TO
BRIEFLY DEVELOP OVER THE CAROLINAS. ANY WEDGING IS EXPECTED TO BE
SHORT LIVED WITH THE LOW LVL FLOW BECOMING WEAKER SAT AFTERNOON AND
EVENING. THE PERIOD ENDS EARLY SUN WITH THE NEXT COLD FRONT STILL
WELL TO OUR WEST AND MOSTLY LIGHT AND VRB FLOW OVER THE CWFA. AS FOR
THE SENSIBLE FCST...THE BEST CHANCES FOR ADDITIONAL PRECIP WILL BE
ON FRI WITH LOWER CHANCES FOR SAT AND SUN. MAX TEMPS WILL STRUGGLE
TO GET REACH CLIMO WHILE MIN TEMPS SHOULD START OUT ABOUT A CATEGORY
ABOVE AND COOL AROUND 2 TO 4 DEGREES THRU THE PERIOD.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 255 AM EDT THURSDAY...THE MEDIUM RANGE FCST BEGINS AT 12Z ON
SUNDAY WITH FLAT UPPER RIDGING OVER THE GULF OF MEX AND ANOTHER
UPPER TROF DIGGING DOWN OVER MINNESOTA AND THE WESTERN GREAT LAKES.
OVER THE REMAINDER OF THE PERIOD...THE LONG RANGE MODELS GRADUALLY
MOVE THE TROF EASTWARD AND EVENTUALLY LIFT IT NE OF NEW ENGLAND. THE
LATEST 00Z RUN OF THE GFS REMAINS FASTER WITH THE TROFS PROGRESSION
COMPARED TO THE ECMWF...HOWEVER THEY ARE MORE SIMILAR THAN BEFORE
WITH BOTH MODELS DEVELOPING A CLOSED LOW BY EARLY NEXT WEEK. THE
UPPER RIDGING WILL REAMPLIFY OVER THE CENTRAL CONUS IN THE TROFS
WAKE BY MID TO LATE NEXT WEEK WITH THE GFS STILL QUITE A BIT MORE
ROBUST WITH THE RIDGE. AT THE SFC...LINGERING HIGH PRESSURE WILL BE
IN PLACE OVER THE REGION ON SUNDAY. ANOTHER COLD FRONT WILL APPROACH
THE CWFA LATE SUN/EARLY MON AND MOVE ACROSS THE CWFA DURING THE DAY.
THE GFS CONTINUES TO BE FASTER AND A BIT DRIER OVERALL WITH THE
FROPA COMPARED TO THE ECMWF...YET BOTH MODELS ARE LOOKING PRETTY DRY
AT THIS POINT. ANOTHER HIGH WILL PUSH INTO THE REGION BEHIND THE
FRONT ON TUES AND LINGER THRU THE REMAINDER OF THE MEDIUM RANGE.
AS FOR THE SENSIBLE WX...NO SIGNIFICANT CHANGES WERE NEEDED WITH A
SLIGHT TO SOLID CHANCE POP EACH DAY AND TEMPS JUST ABOVE NORMAL FOR
LATE AUGUST.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
AT KCLT...LOW CLOUDS CLEARED QUICKER THAN EXPECTED THIS MORNING...
BUT EXPECT MVFR CU TO DEVELOP WITH THE EARLIER THAN EXPECTED
HEATING. STILL EXPECT AFTERNOON TSRA...BUT THE CURRENT TIMING MAY
NEED TO BE ADJUSTED AS DEVELOPMENT HAS BEEN SLOWER. WINDS GENERALLY
SW 5KT OR LESS THROUGH MOST OF THE PERIOD...BUT SHIFTING NW AS THE
FRONT APPROACHES AND MOVES THROUGH. CURRENT TIMING IS AROUND 05Z.
FOR NOW...VFR FOR FRIDAY MORNING BUT HIGHLY DEPENDENT ON CONVECTIVE
COVERAGE AND AMOUNT OF PRECIP THIS AFTERNOON/EVENING.
ELSEWHERE...SIMILAR TRENDS TO KCLT...BUT QUICKER ONSET OF MVFR CU.
WILL LIKELY SEE ANOTHER ROUND OF LOW CIGS FRIDAY MORNING...BUT
ACTUAL RESTRICTIONS WILL DEPEND ON CONVECTIVE COVERAGE AND AMOUNT OF
PRECIP RECEIVED THIS AFTERNOON AND EVENING. INTRODUCED RESTRICTIONS
AT KAVL BUT OTHERWISE WILL HAVE TO MONITOR TRENDS FOR TODAY.
OUTLOOK...LINGERING LOW LEVEL MOISTURE MAY RESULT IN RESTRICTIONS IN
FOG/STRATUS EARLY FRIDAY. DRY HIGH PRESSURE BUILDING IN FROM THE
NORTH WILL LIMIT RESTRICTIONS THROUGH THE WEEKEND.
CONFIDENCE TABLE...
14-20Z 20-02Z 02-08Z 08-12Z
KCLT MED 74% HIGH 100% HIGH 100% HIGH 100%
KGSP MED 72% HIGH 100% HIGH 100% HIGH 100%
KAVL LOW 56% HIGH 88% HIGH 97% HIGH 81%
KHKY MED 68% HIGH 100% HIGH 95% MED 70%
KGMU MED 68% HIGH 100% HIGH 100% HIGH 100%
KAND MED 74% HIGH 100% HIGH 100% 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
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...RWH/TDP
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...RWH/TDP
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
736 AM EDT THU AUG 20 2015
.SYNOPSIS...
A WEAK COLD FRONT WILL APPROACH THE AREA FROM THE WEST TODAY
BRINGING INCREASED CHANCES FOR SHOWERS AND THUNDERSTORMS. IN THE
FRONTS WAKE...SOME DRYING IS EXPECTED OVER THE WEEKEND. ANOTHER WEAK
FRONT APPROACHES THE CAROLINAS ON MONDAY WITH HIGH PRESSURE MOVING
OVER THE REGION BEHIND THE FRONT.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM THURSDAY...ONLY ISOLATED SHOWERS CONTINUE FOR THE
UPDATE...SO HAVE REDUCED POPS SIGNIFICANTLY THROUGH THE MORNING. AS
MENTIONED BELOW...HIRES GUIDANCE CONTINUES TO NOT BE VERY EXCITED
ABOUT CONVECTIVE POTENTIAL THIS AFTERNOON THOUGH SYNOPTIC MODELS
CONTINUE TO PAINT CONVECTIVE PRECIP ACROSS THE AREA. WITH THIS
UNCERTAINTY AND GIVEN PERSISTENCE TRENDS...MADE ONLY MINOR
ADJUSTMENTS TO AFTERNOON POPS.
AS OF 230 AM THURSDAY...BENIGN CONDITIONS AT AFD TIME...BUT THIS
AFTER QUITE AN EVENTFUL EVENING YESTERDAY. WARM RAIN PROCESSES AND
TRAINING CELLS RESULTED IN ANOTHER 5+ INCHES OF RAIN ACROSS PORTIONS
OF UNION COUNTY NC WHERE SOME SIGNIFICANT FLASH FLOODING WAS
REPORTED. GOOSE CREEK REMAINS HIGH WITH ONE POINT STILL IN FLOOD AT
AFD TIME.
ONTO THE FORECAST...DEEP UPPER TROUGH STRETCHING DOWN THE
MISSISSIPPI WILL BEGIN TO LIFT INTO THE GREAT LAKES AND SOUTHEAST
CANADA TODAY...WITH AN OCCLUDED COLD FRONT PUSHING TOWARD THE
SOUTHERN APPALACHIANS. THE SOUTHERN EDGE OF THE FRONT IS PROGGED TO
PUSH THROUGH THE FORECAST AREA TONIGHT BUT WASH OUT QUICKLY.
DEWPOINTS BY SUNRISE FRIDAY WILL ACTUALLY DROP INTO THE UPPER 60S
ACROSS THE UPSTATE WITH SOME UPPER 50S IN THE MOUNTAINS. WE WILL
ALSO SEE LOW TEMPERATURES A COUPLE OF DEGREES COOLER THAN WE HAVE
BEEN EXPERIENCING LATELY...BUT THE DECREASE IN DEWPOINTS WILL NOT BE
QUITE QUICK ENOUGH TO BRING LOWS DOWN TO SEASONAL NORMALS JUST YET.
ANOTHER WEAK SHORTWAVE DIVING TOWARD THE OHIO VALLEY TONIGHT...WITH
A FAIRLY POTENT VORT LOBE...WILL SERVE TO PULL UP ADDITIONAL
MOISTURE AS SURFACE PATTERN TRANSITIONS TO HIGH PRESSURE.
BIGGEST CONCERN OF THE NEAR TERM WILL BE CHANCE OF ADDITIONAL
CONVECTION TODAY. WITH THE APPROACH AND PASSAGE OF THE COLD FRONT...
CERTAINLY THERE IS ENOUGH SYNOPTIC FORCING...AND WITH PW VALUES
REMAINING GENERALLY AT OR ABOVE 2 INCHES...WE SHOULD CONTINUE TO SEE
FAIRLY EFFICIENT RAIN PRODUCERS. NOT GOOD NEWS FOR FOLKS THAT
EXPERIENCED SOME SIGNIFICANT RAINFALL AMOUNTS AND RESULTING FLASH
FLOODING LAST NIGHT. LUCKILY SBCAPE VALUES GENERALLY REMAIN BELOW
1000 J/KG SO CONVECTIVE INTENSITY SHOULD NOT BE QUITE AS BAD AS
YESTERDAY. ALL THAT SAID...HI-RES GUIDANCE NOT PARTICULARLY
IMPRESSED WITH CONVECTIVE POTENTIAL FOR THIS AFTERNOON. HRRR ONLY
HAS ISOLATED CONVECTION AT BEST EVEN THROUGH 20Z. WRF NMM AND ARW
REFLECTIVITY GUIDANCE ON PAR WITH THE HRRR. WITH THAT...KEPT POPS AT
CHANCE AT BEST ACROSS THE UPSTATE AND MOST OF THE NC PIEDMONT...WITH
LIKELIES IN THE MOUNTAINS. CONFIDENCE NOT PARTICULARLY HIGH SO WILL
HAVE TO MONITOR THROUGH THE DAY.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 310 AM EDT THURSDAY...THE SHORT TERM FCST PICKS UP AT 12Z ON
FRIDAY WITH THE UPPER TROF LIFTING NE OF THE GREAT LAKES AS HEIGHTS
BEGIN TO RISE OVER THE SE REGION. THIS PATTERN WILL PERSIST INTO THE
MEDIUM RANGE WITH VARIOUS LOBES OF SHORTWAVE ENERGY APPROACHING THE
CWFA FROM THE WEST OVER THE WEEKEND. IN ADDITION...ANOTHER COMPACT
UPPER TROF WILL DIG DOWN OVER THE US/CANADA BORDER OVER THE WEEKEND
AND MOVE ACROSS THE GREAT LAKES BY THE START OF THE MEDIUM RANGE.
ON FRIDAY...THE SFC HIGH GRADUALLY SLIDES EASTWARD AND THEN NE THRU
THE DAY AND EVENING WITH LOW LVL DRYING AS THE BNDY LAYER FLOW
BECOMES MORE NLY. THE GFS SOLUTION CONTINUES TO BE THE DRIEST MODEL
OVERALL WITH THE NAM BEING THE WETTEST. REGARDLESS OF MODEL
CHOICE...THE TREND IS FOR DRIER PROFILES AND LESS INFLUENCE FROM THE
GULF AS WE MOVE INTO SAT. ON SATURDAY...THE SFC HIGH SLIDES A BIT
FARTHER NE AND UP OVER NEW ENGLAND AS SOME WEAK WEDGING APPEARS TO
BRIEFLY DEVELOP OVER THE CAROLINAS. ANY WEDGING IS EXPECTED TO BE
SHORT LIVED WITH THE LOW LVL FLOW BECOMING WEAKER SAT AFTERNOON AND
EVENING. THE PERIOD ENDS EARLY SUN WITH THE NEXT COLD FRONT STILL
WELL TO OUR WEST AND MOSTLY LIGHT AND VRB FLOW OVER THE CWFA. AS FOR
THE SENSIBLE FCST...THE BEST CHANCES FOR ADDITIONAL PRECIP WILL BE
ON FRI WITH LOWER CHANCES FOR SAT AND SUN. MAX TEMPS WILL STRUGGLE
TO GET REACH CLIMO WHILE MIN TEMPS SHOULD START OUT ABOUT A CATEGORY
ABOVE AND COOL AROUND 2 TO 4 DEGREES THRU THE PERIOD.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 255 AM EDT THURSDAY...THE MEDIUM RANGE FCST BEGINS AT 12Z ON
SUNDAY WITH FLAT UPPER RIDGING OVER THE GULF OF MEX AND ANOTHER
UPPER TROF DIGGING DOWN OVER MINNESOTA AND THE WESTERN GREAT LAKES.
OVER THE REMAINDER OF THE PERIOD...THE LONG RANGE MODELS GRADUALLY
MOVE THE TROF EASTWARD AND EVENTUALLY LIFT IT NE OF NEW ENGLAND. THE
LATEST 00Z RUN OF THE GFS REMAINS FASTER WITH THE TROFS PROGRESSION
COMPARED TO THE ECMWF...HOWEVER THEY ARE MORE SIMILAR THAN BEFORE
WITH BOTH MODELS DEVELOPING A CLOSED LOW BY EARLY NEXT WEEK. THE
UPPER RIDGING WILL REAMPLIFY OVER THE CENTRAL CONUS IN THE TROFS
WAKE BY MID TO LATE NEXT WEEK WITH THE GFS STILL QUITE A BIT MORE
ROBUST WITH THE RIDGE. AT THE SFC...LINGERING HIGH PRESSURE WILL BE
IN PLACE OVER THE REGION ON SUNDAY. ANOTHER COLD FRONT WILL APPROACH
THE CWFA LATE SUN/EARLY MON AND MOVE ACROSS THE CWFA DURING THE DAY.
THE GFS CONTINUES TO BE FASTER AND A BIT DRIER OVERALL WITH THE
FROPA COMPARED TO THE ECMWF...YET BOTH MODELS ARE LOOKING PRETTY DRY
AT THIS POINT. ANOTHER HIGH WILL PUSH INTO THE REGION BEHIND THE
FRONT ON TUES AND LINGER THRU THE REMAINDER OF THE MEDIUM RANGE.
AS FOR THE SENSIBLE WX...NO SIGNIFICANT CHANGES WERE NEEDED WITH A
SLIGHT TO SOLID CHANCE POP EACH DAY AND TEMPS JUST ABOVE NORMAL FOR
LATE AUGUST.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AT KCLT...SEEING QUITE A BIT OF IFR CIGS AROUND CLT SO WILL START
THE TAF WITH MVFR TEMPO IFR FOR A COUPLE OF HOURS. SLOW LIFTING
TREND THROUGH THE MORNING BUT SHOULD BE VFR AROUND 15Z OR SO. BEST
TIMING FOR AFTERNOON TSRA IS 18-22Z SO INCLUDED TEMPO FOR THAT.
WINDS GENERALLY SW 5KT OR LESS THROUGH MOST OF THE PERIOD...BUT
SHIFTING NW AS THE FRONT APPROACHES AND MOVES THROUGH. CURRENT
TIMING IS AROUND 05Z. FOR NOW...VFR FOR FRIDAY MORNING BUT HIGHLY
DEPENDENT ON CONVECTIVE COVERAGE AND AMOUNT OF PRECIP THIS
AFTERNOON/EVENING.
ELSEWHERE...OVERALL SIMILAR TREND TO KCLT BUT WITH SLOWER LIFTING TO
CIGS THIS MORNING. IN ADDITION TO TEMPO TSRA 18-22Z AT ALL SITES...
WENT VCTS FOR KAVL/KHKY AS THE FRONT APPROACHES. WILL LIKELY SEE
ANOTHER ROUND OF LOW CIGS FRIDAY MORNING...BUT ACTUAL RESTRICTIONS
WILL DEPEND ON CONVECTIVE COVERAGE AND AMOUNT OF PRECIP RECEIVED
THIS AFTERNOON AND EVENING. INTRODUCED RESTRICTIONS AT KAVL BUT
OTHERWISE WILL HAVE TO MONITOR TRENDS FOR TODAY.
OUTLOOK...LINGERING LOW LEVEL MOISTURE MAY RESULT IN RESTRICTIONS IN
FOG/STRATUS EARLY FRIDAY. DRY HIGH PRESSURE BUILDING IN FROM THE
NORTH WILL LIMIT RESTRICTIONS THROUGH THE WEEKEND.
CONFIDENCE TABLE...
11-17Z 17-23Z 23-05Z 05-06Z
KCLT MED 78% HIGH 100% HIGH 100% HIGH 100%
KGSP HIGH 83% HIGH 100% HIGH 100% HIGH 100%
KAVL MED 78% LOW 55% LOW 55% HIGH 93%
KHKY HIGH 89% MED 60% HIGH 100% HIGH 83%
KGMU MED 64% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 83% HIGH 100% HIGH 100% 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
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...TDP
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...TDP
AREA FORECAST DISCUSSION...UPDATED
NWS MORRISTOWN TN
956 AM EDT THU AUG 20 2015
.DISCUSSION...
A BAND OF SHOWERS ALONG THE COLD FRONT IS MAKING SLOW EASTWARD
PROGRESS...AND REFLECTIVITY TRENDS SHOW DECREASING INTESITY TO THE
RAINFALL. THE HRRR CONTINUES THIS WEAKENING TREND INTO THE
AFTERNOON. THE 12Z RNK AND FFC SOUNDINGS SHOW VERY LITTLE
INSTABILITY TO SUPPORT THUNDERSTORMS TODAY. THERE HAS BEEN SOME
HEATING WITH A LACK OF CLOUD COVER THIS MORNING NEAR THE
MOUNTAINS...SO THIS MIGHT STILL AID SOME THUNDERSTORMS THIS
AFTERNOON IN THAT AREA...BUT COVERAGE SHOULD BE LIMITED TO
ISOLATED. WILL UPDATE TO ADJUST POPS AND QPF BASED ON THESE TRENDS.
THE LATEST MODEL AND RADAR TRENDS SUGGEST THAT THE FRONT WILL BE
NEAR OUR EASTERN BORDER AROUND 00Z AND TO OUR EAST BY MIDNIGHT...SO
THE UPDATE WILL BRING POPS TO AN END MORE QUICKLY. THIS WILL
NECESSITATE SOME CHANGES TO THE FRIDAY PERIOD...REMOVING ALL POPS
FROM FRIDAY IN THE DRY AND STABLE ENVIRONMENT BEHIND THE FRONT.
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
DGS
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1020 AM CDT THU AUG 20 2015
.UPDATE...
LINGERING SCATTERED SHOWERS WILL CONTINUE INTO THE LATE MORNING
HOURS AS 500 MB SHORTWAVE TROUGH AND ASSOCIATED SFC LOW PRESSURE
IS SITUATED TO OUR NORTH. HOWEVER...SHORTWAVE WILL MOVE OFF TO THE
NORTH AND EAST...DIMINISHING SHOWER ACTIVITY BY THE AFTERNOON AND
SLOWLY CLEARING OUT SKIES BY THE LATE AFTERNOON AND EVENING.
WESTERLY WINDS WILL REMAIN GUSTY THIS AFTERNOON WITH GOOD
BOUNDARY LAYER MOMENTUM TRANSPORT ACCORDING TO RAP AND NAM BUFKIT
SOUNDINGS. WINDS WILL SLOWLY SHIFT TO A MORE NORTHWESTERLY
DIRECTION THIS AFTERNOON AND EVENING AS LOW PRESSURE SHIFTS TO THE
EAST.
&&
.AVIATION/18Z TAFS/...
VCSH WILL COME TO AN END LATE THIS MORNING AND AFTERNOON AS AN
AREA OF LOW PRESSURE TO OUR NORTH WILL SLOWLY MOVE ITS WAY TO THE
NORTH AND EAST. AS LOW PRESSURE MOVES AWAY...SKIES WILL SLOWLY
CLEAR OUT AND CIG HEIGHTS WILL IMPROVE BY AFTERNOON. WESTERLY WINDS
WILL STAY GUSTY THIS AFTERNOON AS BUFKIT RAP AND NAM SOUNDINGS
INDICATE GOOD MOMENTUM TRANSPORT IN THE BOUNDARY LAYER...BUT WILL
WEAKEN BY THE EVENING HOURS AS SFC PRESSURE GRADIENT WEAKENS AND
BOUNDARY LAYER DECOUPLES. WINDS ARE EXPECTED TO VEER SLIGHTLY
FROM THE NORTHWEST THIS AFTERNOON AND EVENING.
&&
.PREV DISCUSSION... /ISSUED 330 AM CDT THU AUG 20 2015/
TODAY AND TONIGHT... FORECAST CONFIDENCE - HIGH.
MID-LEVEL SHORT WAVE ROTATING AROUND UPPER LOW PRODUCING SCATTERED
-SHRA AND SPRINKLES...MAINLY OVER NRN AND PARTS OF EASTERN CWA
OVERNIGHT. -SHRA WL CONTINUE TO DIMINISH THROUGH 12Z BUT SOME
LINGERING SPRINKLES ARE POSSIBLE AS LOW PRESSURE TROF LINGERS OVER
AREA THRU MID-MRNG. THERMAL TROF AND WEAK COLD AIR ADVECTION WL
CONTINUE TO BRING STRATUS TO MOST OF THE AREA THRU THE MORNING.
HOWEVER UPPER LOW WL BE WEAKENING AND SHIFTING NORTHEAST THRU THE
DAY IN RESPONSE TO UPSTREAM WEAK KICKER SYSTEM CROSSING SRN
CANADA. WITH THERMAL TROF SHIFTING EAST AND THINNING COLUMN
MOISTURE... EXPECT DECREASING CLOUDS FROM WEST TO EAST FROM LATE
MRNG THRU THE EARLY EVE.
ANOTHER BREEZY DAY IS EXPECTED DUE TO LINGERING PRESSURE GRADIENT
BUT WINDS WILL DROP OFF RAPIDLY WITH LOSS OF INSOLATION EARLY THIS
EVENING. MOSTLY CLEAR SKIES AND LIGHTER SFC WINDS WILL ALLOW TEMPS
TO FALL INTO THE UPPER 40S TO LOWER 50S MOST AREAS...WHICH WILL BE
THE COOLEST NIGHT SINCE EARLY JULY. LIGHTER BOUNDARY LAYER WINDS
ACROSS THE WESTERN CWA SHOULD ALLOW VALLEY FOG TO DEVELOP AFTER
MIDNIGHT. MID-LEVEL CLOUDS WILL INCREASE ACROSS FAR WESTERN CWA
LATE TONIGHT DUE TO UPSTREAM MID-LEVEL WARM AIR ADVECTION SURGE.
FRIDAY AND SATURDAY...FORECAST CONFIDENCE...HIGH
HIGH PRESSURE CENTERED TO THE EAST OF WISCONSIN WILL BRING VERY
PLEASANT WEATHER TO THE FORECAST AREA FRIDAY AND SATURDAY. MID
LEVEL WARM ADVECTION MAY BRING SOME CLOUDS FOR FRIDAY
MORNING...DIMINISHING IN THE AFTERNOON. LOOKS LIKE PLENTY OF
SUNSHINE THEN SATURDAY. HIGHS BOTH DAYS WILL BE WITHIN A COUPLE
DEGREES OF NORMAL IN THE UPPER 70S AND LOW 80S. SOUTHERLY WINDS
WILL BE A BIT BREEZY ON THE WESTERN EDGE OF THE HIGH.
SATURDAY NIGHT THROUGH WEDNESDAY...FORECAST CONFIDENCE...MEDIUM
A COLD FRONT IS EXPECTED TO BRING A CHANCE FOR SHOWERS AND STORMS
TO THE FORECAST AREA SATURDAY NIGHT INTO SUNDAY. MODELS ARE IN
PRETTY GOOD AGREEMENT THAT THE BEST CHANCE WILL BE BETWEEN
MIDNIGHT SATURDAY NIGHT AND NOON SUNDAY.
DRY WEATHER IS THEN EXPECTED THROUGH WEDNESDAY UNDER HIGH
PRESSURE.
SHOULD SEE HIGH TEMPS A COUPLE TO FEW DEGREES BELOW NORMAL VALUES
FOR THE FIRST HALF OF NEXT WEEK.
AVIATION/12Z TAFS/...
STILL EXPECT MOSTLY MVFR CIGS THIS MRNG AS LOW PRESSURE OVER LAKE
SUPERIOR PUSHES NORTHWARD INTO SRN CANADA. LATEST SFC OBS AND 11-
3.9 MICRON IMAGERY SHOWING SOME THIN SPOTS AND HOLES IN THE STRATUS
FIELD BRUSHING FAR SRN WI. HIGHER CIGS MAY BRIEFLY AFFECT TAF SITES
FOR AN HOUR OR TWO EARLY THIS MRNG. ALSO...SCATTERED -SHRA AND
SPRINKLES WILL DIMINISH THIS MRNG. DEEPER MOISTURE AND THERMAL TROF
SHIFT EWD TODAY SO STILL EXPECT DECREASE IN CLOUD COVER AND RAISING
CIGS THIS AFTN AND EARLY EVE.
MARINE...
EXPECT ANOTHER DAY OF GUSTY SOUTHWEST WINDS VEERING TO THE WEST THIS
MORNING AS LOW PRESSURE MOVES FROM NEAR LAKE SUPERIOR ACROSS
SOUTHERN CANADA TOWARD HUDSON BAY. SEVERAL TUGS MOVING NORTH IN THE
NEARSHORE WATERS OF LAKE MICHIGAN HAVE REPORTED SUSTAINED WINDS OF
18 TO 20 KNOTS OVER THE LAST SEVERAL HOURS. FREQUENT GUSTS TO
AROUND 25 KTS ARE EXPECTED TO REDEVELOP LATER THIS MORNING
CONTINUING THRU THE AFTN. HENCE THE SMALL CRAFT ADVISORY WILL
REMAIN IN EFFECT THRU 00Z. THE GUSTY WEST WINDS WILL DIMINISH
RAPIDLY EARLY THIS EVE.
BEACHES...
ANOTHER BREEZY DAY LIES AHEAD FOR BEACHES ALONG LAKE MICHIGAN. THE
SWIM RISK HOWEVER WILL BE LOW DUE TO MORE OF AN OFFSHORE WEST WIND
EXPECTED...RESULTING IN WAVE HEIGHTS OF 1 TO 3 FEET. MORNING CLOUDS
WILL GRADUALLY CLEAR IN THE AFTN/EARLY EVE.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR LMZ643>646.
&&
$$
UPDATE...JTS
TODAY/TONIGHT AND AVIATION/MARINE...MBK
FRIDAY THROUGH WEDNESDAY...DDV
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
603 AM CDT THU AUG 20 2015
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 316 AM CDT THU AUG 20 2015
MAIN FORECAST CONCERNS ARE ON LINGERING LIGHT RAIN SHOWERS THIS
MORNING AND CLOUD TRENDS THROUGH THE DAY AS LOW PRESSURE EXITS.
LATEST WATER VAPOR IMAGERY EARLY THIS MORNING SHOWED UPPER LEVEL LOW
PRESSURE OVER SOUTHWEST ONTARIO LIFTING NORTHEAST. A TRAILING
TROUGH ACROSS THE UPPER MISSISSIPPI RIVER VALLEY WILL GRADUALLY
PROGRESS NORTHEAST TODAY. ISOLATED SHOWERS AND PATCHY DRIZZLE WILL
CONTINUE THIS MORNING MAINLY ALONG AND EAST OF THE MISSISSIPPI RIVER
ACROSS WESTERN INTO CENTRAL WISCONSIN . WE SHOULD SEE THIS
ACTIVITY TAPER OFF BY MID MORNING AND EXIT TO THE NORTHEAST BY
EARLY THIS AFTERNOON. LATEST IR IMAGERY AND SURFACE OBSERVATIONS
SHOW CLOUDS WERE CLEARING WEST OF THE INTERSTATE 35 CORRIDOR IN
SOUTHERN MINNESOTA/NORTHERN IOWA. HOWEVER..TAKING A LOOK UPSTREAM
TO THE NORTHWEST A FAIRLY EXPANSIVE CLOUD DECK REMAINED AND IS
EXPECTED TO MOVE SOUTHEAST AS MOISTURE CONTINUES TO WRAP AROUND
THE TROUGH. THIS WILL CREATE A CHALLENGING CLOUD FORECAST FOR
TODAY. FORECAST GUIDANCE IS TRYING TO PUSH THE CLOUDS EAST FAIRLY
QUICKLY THIS MORNING INTO THIS AFTERNOON AND IN FACT SEEMS A
LITTLE TOO FAST GIVEN OBSERVATIONS THIS MORNING. HAVE SLOWED THE
CLEARING TREND IN CLOUD COVER TODAY WITH CLEARING EXPECTED TO
APPROACH THE MISSISSIPPI RIVER FROM THE WEST BY EARLY THIS
AFTERNOON. WE SHOULD THEN SEE A GRADUAL DECREASE IN CLOUD COVER
ACROSS WESTERN INTO CENTRAL WISCONSIN THROUGH THE AFTERNOON INTO
THE EARLY EVENING HOURS. PLAN ON HIGHS TODAY RANGING FROM AROUND
60 ACROSS NORTHERN WISCONSIN TO THE UPPER 60S TO LOWER 70S ACROSS
SOUTHEAST MINNESOTA INTO NORTHEAST IOWA. A WEAK RIDGE THEN BUILDS
IN TONIGHT WITH QUIET WEATHER EXPECTED. A WEAK SHORTWAVE MOVES
THROUGH OVERNIGHT BRINGING SOME SCATTERED TO BROKEN CLOUD COVER TO
THE AREA.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 316 AM CDT THU AUG 20 2015
MAIN FORECAST CONCERNS ARE ON GUSTY SOUTHERLY WINDS ON SATURDAY THEN
FOCUS TURNS TO THUNDERSTORM CHANCES LATE SATURDAY AFTERNOON
THROUGH SATURDAY NIGHT.
SOUTHERLY FLOW INCREASES ACROSS THE UPPER MISSISSIPPI RIVER VALLEY
ON FRIDAY AS THE PRESSURE GRADIENT TIGHTENS BETWEEN HIGH PRESSURE
CENTERER OVER THE EASTERN GREAT LAKES/NEW ENGLAND AND LOW PRESSURE
DEVELOPING OVER THE NORTHERN PLAINS. IT WILL BE BREEZY ON FRIDAY
WITH SOUTH WINDS OF 11 TO 17 MPH WITH GUSTS APPROACHING 28 MPH
DURING THE AFTERNOON HOURS. LOOK FOR HIGHS TO REBOUND INTO THE MID
70S TO AROUND 80. THE PRESSURE GRADIENT WILL CONTINUE TO STRENGTHEN
ON SATURDAY AS A COLD FRONT AND TROUGH APPROACH FROM THE WEST. IT
WILL BE A WINDY DAY ACROSS THE REGION WITH SOUTH WINDS OF 15 TO 25
MPH WITH GUSTS APPROACHING 35 MPH IN OPEN AREAS. WE SHOULD SEE
INCREASING MOISTURE AHEAD OF THE COLD FRONT ALLOWING 0-1 MUCAPE
VALUES TO CLIMB INTO THE 1000 TO 2000 J/KG RANGE WEST OF THE
MISSISSIPPI RIVER. THUNDERSTORMS LOOK TO INITIATE SATURDAY
AFTERNOON NEAR THE INTERSTATE 35 CORRIDOR THEN PUSH EAST INTO
EASTERN MINNESOTA/IOWA. THE CAPE THEN REALLY STARTS TO WANE AS THE
STORMS PROGRESS EAST DURING THE LATE MORNING INTO THE OVERNIGHT
HOURS. ITS INTERESTING TO NOTE THAT STRONGER SHEAR ATTEMPTS TO
CATCH UP TO THE CAPE AXIS SATURDAY EVENING WHICH COULD CREATE A
WINDOW OF OPPORTUNITY FOR A FEW STRONG TO PERHAPS SEVERE STORMS
WEST OF THE MISSISSIPPI RIVER. 0-3 KM BULK SHEAR VALUES INCREASE
TO 30 TO 35 KTS ACROSS THESE AREAS. IF THIS OCCURS...THE MAIN
HAZARD FROM ANY STRONG TO POSSIBLY SEVERE STORMS WOULD BE SOME
DAMAGING WIND GUSTS. THE FRONT WILL SWEEP THOUGH THE FORECAST AREA
THEN SATURDAY NIGHT...EXITING BY EARLY SATURDAY MORNING. THE UPPER
TROUGH THEN SWINGS THROUGH ON SUNDAY AND MAY PRODUCE SCATTERED
SHOWERS ACROSS WESTERN INTO CENTRAL WISCONSIN. HIGH PRESSURE THEN
BUILDS INTO THE REGION MONDAY INTO WEDNESDAY WITH DRY AND QUIET
WEATHER EXPECTED. WILL HAVE TO KEEP AN EYE ON VALLEY FOG POTENTIAL
WEDNESDAY AND POSSIBLY THURSDAY MORNINGS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 603 AM CDT THU AUG 20 2015
SATELLITE IMAGERY THIS MORNING SHOWS THE BACK EDGE OF THE CLOUDS
MAY BE ADVANCING TO THE NORTHEAST A LITTLE QUICKER THAN EXPECTED.
THE 20.09Z RAP SEEMS TO HAVE A DECENT HANDLE ON THIS AND INDICATES
KRST SHOULD SCATTERED OUT BY MID MORNING. KLSE COULD SCATTER OUT
LATE THIS MORNING...BUT SOMEWHAT CONCERNED THAT THE WESTERN EDGE
OF THE CLOUDS COULD SLOW DOWN OR EXPAND AS THE HEATING CREATES
SOME OMEGA THROUGH THE MOISTURE FIELD. BASED ON THIS...WILL HOLD
THE CLOUDS IN UNTIL EARLY AFTERNOON AT KLSE BUT BY THIS TIME
EXPECT THEM TO BE VFR. THE NORTHWEST WINDS WILL BE A BIT GUSTY
UNTIL THE GRADIENT RELAXES LATE THIS AFTERNOON. HIGH PRESSURE
BUILDS IN TONIGHT FOR CLEAR SKIES. NOT EXPECTING ANY VALLEY FOG AS
THE 20.06Z NAM CONTINUES TO SHOW WINDS OF 15 TO 20 KNOTS AT THE
TOP OF THE LOW LEVEL INVERSION AND ALSO DOES NOT SATURATE BELOW
THE INVERSION.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04
AREA FORECAST DISCUSSION
NWS TUCSON AZ
943 AM MST THU AUG 20 2015
.SYNOPSIS...EXPECT ISOLATED TO SCATTERED THUNDERSTORMS MAINLY FROM
TUCSON EAST AND SOUTH THROUGH TONIGHT. INCREASING CHANCES FOR
SHOWERS AND THUNDERSTORMS WILL THEN BEGIN FRIDAY WITH THE BEST
CHANCE OF WIDESPREAD RAINFALL EARLY NEXT WEEK. THE INCREASED
MOISTURE WILL ALSO KEEP DAYTIME TEMPERATURES CLOSE TO SEASONAL
AVERAGES FRIDAY INTO EARLY NEXT WEEK.
&&
.DISCUSSION...SATELLITE IMAGERY WAS SHOWING SOME CLOUDS ALREADY
STARTING TO BUILD UP ACROSS FAR SOUTHEAST ARIZONA AND IN THE WHITE
MOUNTAINS THIS MORNING. MOISTURE WILL CONTINUE TO INCREASE TODAY AND
MORE SO THIS WEEKEND. THAT SAID...CHANCES OF RAIN WILL BE GOING UP
GRADUALLY STARTING TODAY. CURRENT FORECAST APPEARED TO HANDLE THE
TRENDS WELL...SO NO UPDATES NECESSARY THIS MORNING. PLEASE REFER TO
THE ADDITIONAL SECTIONS FOR MORE DETAILS.
&&
.AVIATION...VALID THRU 21/12Z.
FEW-SCT CLOUDS ABV 12K FT. AFT 20/21Z SCT TO LOCALLY BKN 8-10K FT
AND SCT-BKN LYRS AOA 12K FT. CHANCE FOR -SHRA/-TSRA FROM KTUS SOUTH
AND EAST...WITH AN EMPHASIS ON THE SOUTHERN TERMINALS KOLS AND KDUG.
BRIEF MVFR CONDITIONS AND GUSTY WINDS MAY BE POSSIBLE NEAR STRONGER
TSRA. OTHERWISE...WINDS WILL GENERALLY BE LIGHT AND TERRAIN DRIVEN
UNDER 10 KTS EXCEPT WLY 6-13KTS 20/21Z THRU 21/03Z. AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...MOISTURE WILL START TO INCREASE TODAY WITH ISOLATED
SHOWERS AND THUNDERSTORMS POSSIBLE...MAINLY SOUTHERN AREAS. THEN
THE MOISTURE AND THUNDERSTORMS CHANCES WILL INCREASE AND SPREAD
THROUGHOUT SOUTHEAST ARIZONA THROUGH THE WEEKEND INTO EARLY NEXT
WEEK. WINDS WILL BE TYPICAL FOR MID AUGUST AND GENERALLY LESS THAN
15 MPH THEN THE WIND WILL BECOME EASTERLY MONDAY AND TUESDAY...BUT
AGAIN GENERALLY REMAINING 15 MPH OR LESS.
&&
.PREV DISCUSSION...BASED ON VARIOUS NWP SOLUTIONS...THERE WERE NO
SIGNIFICANT ADJUSTMENTS TO THE INHERITED GRIDDED DATA
POP/WEATHER/TEMP FIELDS FOR THIS FORECAST ISSUANCE. HIGH PRESSURE
ALOFT CENTERED NEAR THE NRN BAJA CALIFORNIA COAST WILL WEAKEN INTO
THIS WEEKEND. THE DRY NWLY FLOW GENERALLY IN THE 700-300MB LAYER
WILL TRANSITION TO LIGHT WLY FLOW FRI AND CONTINUE SAT.
FOR TODAY AND TONIGHT...SEVERAL HRRR SOLUTIONS SUGGEST AN EARLY
START TO SHOWER/TSTM ACTIVITY...PERHAPS BY 18Z-19Z SOUTH-TO-
SOUTHEAST OF TUCSON AND ESPECIALLY FAVORING SANTA CRUZ/SWRN COCHISE
COUNTIES BY MID-AFTERNOON. MEANWHILE...THERE SHOULD BE ENOUGH
MOISTURE TO JUSTIFY ISOLATED SHOWERS/TSTMS THIS AFTERNOON INTO
TONIGHT FROM TUCSON EAST TO THE NEW MEXICO BORDER. PRECIP-FREE
CONDITIONS WILL CONTINUE ACROSS WRN PIMA COUNTY.
20/00Z GFS/ECMWF/CMC SUGGEST THAT PRECIP COVERAGE SHOULD INCREASE
STARTING FRI FOLLOWED BY SCATTERED TO PERHAPS NUMEROUS SHOWERS/
TSTMS...ESPECIALLY SUN INTO MON NIGHT OR SO. THIS SCENARIO SEEMS
REASONABLE GIVEN THAT THE MID AND UPPER FLOW IS PROGGED TO BECOME
ELY/SELY STARTING SUN AND CONTINUING EARLY NEXT WEEK. HAVE NOTED
SOME DISCREPANCIES BETWEEN THE GFS/ECMWF SOLUTIONS FOR EARLY NEXT
WEEK. IN GENERAL...THE 20/00Z GFS TRENDED SOMEWHAT DRIER VERSUS
PREVIOUS GFS SOLUTIONS FOR QPF/S SUN-MON...AND THE 20/00Z ECMWF WAS
MARKEDLY MORE ROBUST WITH QPF/S FOR MON-TUE VERSUS THE 20/00Z GFS.
BASED ON THESE DIFFERENCES...OPTED TO MAKE ONLY VERY MINOR
MODIFICATIONS TO THE GRIDDED DATA POPS SUN-TUE. AT THIS TIME...
APPEARS THAT THE BEST COVERAGE OF SHOWERS/TSTMS SHOULD OCCUR ROUGHLY
SUN AFTERNOON INTO MON NIGHT...OR PERHAPS EARLY TUE. THEREAFTER...
THE GFS TRANSITIONED THE UPPER HIGH CENTER FROM NEAR THE FOUR
CORNERS REGION INTO SERN NEW MEXICO/WEST TEXAS NEXT WED. SWLY FLOW
ALOFT ASSOCIATED WITH THIS SCENARIO WOULD CONFINE SHOWERS/TSTMS
MAINLY TO ERN SECTIONS BY NEXT WED. HOWEVER...THE ECMWF MAINTAINED
THE UPPER HIGH TO BE CENTERED NEAR THE FOUR CORNERS. SLY/SELY FLOW
ALOFT ASSOCIATED WITH THIS SCENARIO WOULD KEEP PRECIP CHANCES HIGHER
FURTHER WWD VERSUS THE GFS SOLUTION. THE UPSHOT...ISOLATED TO
SCATTERED SHOWERS/TSTMS AREA-WIDE NEXT WED...WITH HIGHER POPS ACROSS
GREENLEE/GRAHAM/COCHISE COUNTIES.
HIGH TEMPS TODAY WILL BE QUITE SIMILAR TO TEMPS ACHIEVED WED... AND
WILL CONTINUE TO AVERAGE ABOUT 2-5 DEGS F ABOVE NORMAL. SOME MINOR
COOLING WILL THEN OCCUR FRI FOLLOWED BY NEAR NORMAL DAYTIME TEMPS
FOR MUCH OF THE AREA SAT-TUE. HIGH TEMPS SHOULD TREND UPWARD AND
GENERALLY A FEW DEGS ABOVE NORMAL NEXT WED.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
359 PM EDT THU AUG 20 2015
.SYNOPSIS...
DEEP MOISTURE WILL REMAIN IN THE FORECAST AREA THROUGH FRIDAY.
A WEAK FRONT APPROACHING FROM THE NORTHWEST WILL MOVE INTO THE
AREA TONIGHT AND REMAIN NEAR THE REGION DURING THE REST OF THE
WEEKEND. THERE WILL BE A CONTINUED CHANCE OF SHOWERS AND
THUNDERSTORMS.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
CONVERGENCE ASSOCIATED WITH A PREFRONTAL TROUGH AND HEATING WILL
HELP CAUSE THUNDERSTORMS INTO THE EVENING. SOME CONTINUED
CONVERGENCE NEAR THE WEAK FRONT MOVING INTO THE AREA SUPPORTS A
CONTINUED CHANCE OVERNIGHT. THE MIDAFTERNOON WATER VAPOR IMAGERY
SHOWED SOME DRYING OVER THE AREA INDICATING WE ARE BETWEEN AREAS
OF UPPER-LEVEL LIFT. BELIEVE SOME UPPER-LEVEL LIFT WILL OVERSPREAD
THE REGION TONIGHT AS INDICATED BY WATER VAPOR IMAGERY TRENDS AND
MODEL GUIDANCE SHOWING SHORTWAVE TROUGHS MOVING INTO THE H5 RIDGE
EARLY AND AGAIN TOWARD MORNING. THE HRRR DISPLAYED SCATTERED
COVERAGE INTO THE EVENING. THE SPC WRF SHOWED NUMEROUS SHOWERS AND
THUNDERSTORMS TONIGHT. WE LEANED TOWARD THE HIGHER GUIDANCE POPS.
THE MAIN FORECAST PROBLEM THROUGH TONIGHT IS THE THREAT OF HEAVY
RAIN BECAUSE OF PRECIPITABLE WATER NEAR 2 INCHES AND POSSIBLE
TRAINING. THERE IS LESS OF A DAMAGING WIND THREAT WITH A FORECAST
SOUNDING CLOSE TO MOIST ADIABATIC. THE HIGH MOISTURE FAVORED THE
WARMER TEMPERATURE GUIDANCE TONIGHT.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
BELIEVE THE DIFFUSE FRONT WILL REMAIN STALLED NEAR THE FORECAST
AREA. MOISTURE MAY BECOME MORE SHALLOW...ESPECIALLY IN THE NORTH.
THE NAM INDICATED LESS DRYING COMPARED TO THE GFS. THE PATTERN
FAVORS THE SLOWER TIMING AND WE LEANED TOWARD THE HIGHER MOS
POPS...MAINLY IN THE SOUTH PART WHERE EXPECT MORE MOISTURE AND
GREATER CONVERGENCE ASSOCIATED WITH THE WEAK FRONT.
PRECIPITABLE WATER REMAINING NEAR 2 INCHES INDICATES A
CONTINUED THREAT OF THUNDERSTORMS WITH LOCALLY HEAVY RAIN. USED
THE GUIDANCE CONSENSUS FOR THE HIGH TEMPERATURE FORECAST AND
WARMER GUIDANCE FOR THE LOW TEMPERATURE BECAUSE OF THE RECENT BIAS
AND MOIST AIR MASS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
MOISTURE ASSOCIATED WITH THE REMNANTS OF THE FRONT SHOULD
CONTINUE THROUGH SUNDAY. THE GFS AND ECMWF DISPLAY ANOTHER FRONT
MOVING INTO THE AREA MONDAY WITH THIS FEATURE LINGERING NEAR THE
AREA DURING THE REST OF THE MEDIUM-RANGE PERIOD. HOWEVER...DEEPER
MOISTURE APPEARS TO REMAIN EAST OF THE FORECAST AREA AHEAD OF THE
UPPER TROUGH. THE GFS...ECMWF...AND EKD MOS HAVE POPS OF 20 TO 30
PERCENT THROUGH THE PERIOD.
&&
.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
VFR CONDITIONS EXPECTED FOR MUCH OF THE PERIOD...WITH
RESTRICTIONS POSSIBLE IN AFTERNOON AND EVENING CONVECTION.
CONVERGENCE AHEAD OF AN APPROACHING FRONTAL BOUNDARY COMBINED
WITH DIURNAL HEATING AND ELEVATED MOISTURE WILL PROMOTE CONVECTION
THIS AFTERNOON AND EVENING. MOST OF THE CONVECTION SO FAR HAS BEEN
EAST OF CAE/CUB/AGS/DNL...BUT EXPECT MORE COVERAGE FURTHER WEST
LATER THIS AFTERNOON AND EVENING DUE TO INCREASED UPPER ENERGY.
HAVE ONLY INCLUDED A TEMPO GROUP FOR THUNDERSTORMS AT OGB AS
CONFIDENCE IN TIMING AND COVERAGE REMAINS TOO LOW TO INCLUDE AT
OTHER TAF SITES. THE FRONTAL BOUNDARY WILL CROSS THE TAF SITES
OVERNIGHT WITH CONVECTION DIMINISHING. CANNOT RULE OUT
RESTRICTIONS IN STRATUS/FOG EARLY FRIDAY ALTHOUGH A 20-KNOT LOW
LEVEL JET SHOULD LIMIT FOG POTENTIAL. WINDS WILL BE OUT OF THE
WEST-SOUTHWEST AT 5 TO 10 KNOTS THROUGH THIS EVENING AND WILL
ROTATE TO NORTHERLY OVERNIGHT AS THE FRONT MOVES INTO THE AREA.
SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE AGAIN ON FRIDAY AS THE
FRONT LINGERS NEAR THE AREA.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE FRIDAY IN
SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
99
AREA FORECAST DISCUSSION
NWS DULUTH MN
331 PM CDT THU AUG 20 2015
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 330 PM CDT THU AUG 20 2015
SHOWERS/DRIZZLE ENDING ACROSS THE ARROWHEAD EARLY THIS AFTERNOON
GIVING WAY TO SUNNY AND JUST BELOW SEASONABLE TEMPERATURES ACROSS
THE REGION. CLEAR SKIES AND NEAR-CALM WIND TONIGHT WITH A HIGH
PRESSURE BUILDING IN WILL LEAD TO COOL OVERNIGHT LOWS. SUNNY
AND WARMER ON FRIDAY WITH HIGHS NEAR 80.
ON THE SYNOPTIC SCALE THE BROAD LOW PRESSURE SYSTEM THAT BROUGHT
INTENSE RAINFALL TO THE REGION EARLIER THIS WEEK IS FINALLY
DEPARTING TO THE NORTHEAST. BEHIND THIS SOME LOW-LEVEL RIDGING WILL
BUILD IN TO THE UPPER MIDWEST AS A HIGH PRESSURE BUILDS FROM THE
TENNESSEE TO OHIO RIVER VALLEY. WARM AIR ADVECTION WILL RAMP UP DUE
TO WEST/SOUTHWESTERLY WINDS AT LOW LEVELS TONIGHT INTO TOMORROW. IN
ADDITION...A WEAK WARM FRONT ON THE LEADING EDGE OF THE WARM AIR
ADVECTION WILL MOVE ACROSS MANITOBA INTO NORTHWEST ONTARIO...WHICH
MAY GRAZE THE BORDERLAND WITH SOME SHOWERS OVERNIGHT. WHILE THERE IS
NOT MUCH SUPPORT FROM THE GLOBAL MODEL SUITE AS FAR AS QPF
GOES...MOST MODELS INDICATE THE NECESSARY FORCING WILL BE THERE FOR
A FEW SHOWERS. THE LATEST HRRR RUNS ARE ALSO SUPPORTIVE OF THIS
IDEA...SO INCLUDED SOME LOW POPS UP ALONG THE INTERNATIONAL FALLS
REGION. ON FRIDAY THE LOW-LEVEL RIDGING FLATTENS OUT WITH WEST-
SOUTHWEST FLOW ALOFT RESULTING IN CONTINUED WARM AIR ADVECTION. FOR
REFERENCE...THE 850MB TEMP FROM THIS MORNINGS 12Z SOUNDING AT
INTERNATIONAL FALLS WAS 3.1C...AND THE MODEL CONSENSUS IS FOR THIS
TO RISE TO ABOUT 18C BY FRIDAY AFTERNOON.
TONIGHT...GRADUALLY CLEARING SKIES WITH PATCHY FOG POSSIBLE. WINDS
BECOMING NEAR-CALM IN THE EVENING WHICH SHOULD ALLOW FOR FOG TO
DEVELOP...ESPECIALLY IN NORTHWEST WISCONSIN WHERE THE HEAVIEST
RAINFALL HAS FALLEN OVER THE PAST FEW DAYS. GUIDANCE NOT VERY
SUPPORTIVE OF THE FOG IDEA WHICH IS PROBABLY DUE TO THE DRIER AIR
MOVING IN FROM THE WEST...BUT WITH A WEAK RIDGE OVER THE REGION
TEMPS WILL FALL RAPIDLY AND AT LEAST PATCHY RADIATION FOG SHOULD
DEVELOP. LATER IN THE NIGHT...AFTER MIDNIGHT...SOME HIGH CLOUDS MAY
MOVE IN ACROSS FAR NORTH-CENTRAL MINNESOTA...AND POSSIBLY A SHOWER
OR TWO IN THE INTERNATIONAL FALLS REGION. FOG MAY DISSIPATE BEFORE
SUNRISE IF WINDS PICK UP BY EARLY FRIDAY MORNING...THIS WILL DEPEND
ON THE TIMING OF THE RIDGE AXIS BUT THINKING BY SUNRISE FOG SHOULD
BE GONE EVERYWHERE EXCEPT FOR NORTHERN WISCONSIN NEAR THE UP. LOWS
IN THE LOW/MID 40S TO LOW 50S.
FRIDAY...MOSTLY SUNNY...WARM...AND BREEZY. WINDS OUT OF THE SOUTH AT
10 TO 15 MPH WITH GUSTS TO NEAR 25 MPH. THERE MAY BE AN ISOLATED
SHOWER IN THE MORNING ACROSS THE BORDERLAND...BUT OTHERWISE DRY.
HIGHS IN THE UPPER 70S TO LOW 80S.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 330 PM CDT THU AUG 20 2015
THE MAIN CONCERN FOR THE EXTENDED IS THE THREAT FOR SEVERE WEATHER
SATURDAY AFTERNOON AND NIGHT.
THE SOUTHERLY FLOW CONTINUES ACROSS THE FORECAST AREA FRIDAY NIGHT
OUT AHEAD OF THE SYSTEM. THE NAM AND ECMWF ARE SIMILAR WITH TAKING
THE CENTER ACROSS NORTHERN MN WITH THE GFS KEEPING NORTH OF THE
INTERNATIONAL BORDER. BASED ON CURRENT TRENDS AND PERFORMANCE OF
THE MODELS WITH THE LAST STORM...WILL GO WITH A MIXTURE OF NAM/ECMWF
FOR SOLUTION. THE COLD FRONT WILL ENTER WESTERN LATE SATURDAY
MORNING AND ACROSS THE TWIN PORTS LATE SATURDAY EVENING.
THUNDERSTORMS WILL DEVELOP SATURDAY MORNING IN WRN MN AND MOVE EAST
DURING THE DAY. SPC DAY 3 OUTLOOK INDICATES A SLIGHT RISK MAINLY
EAST OF HIGHWAY 53/I-35 IN MN WITH MARGINAL RISK ACROSS MOST OF THE
REST OF THE FORECAST AREA. AS INDICATED BY THE MID SHIFT...THERE
WILL BE A RISK FOR SEVERE THUNDERSTORMS IN THE AFTERNOON BUT MAY BE
FOCUSED FURTHER WEST IN MN. IT STILL LOOKS LIKE A MCS MAY DEVELOP
LATER IN THE AFTERNOON. IT WILL BE ANOTHER HEAVY RAIN EVENT WITH
PWATS IN THE 1.5 TO 2.0 INCHES EXPECTED ACROSS THE FORECAST AREA.
STORM TOTAL QPF FORECAST IS FOR 1-1.5 INCHES FROM INL TO BRD WITH
0.50 TO 0.75 INCHES FURTHER EAST BY SUNDAY MORNING.
SIMILAR TO THE PAST SYSTEM...MUCH COOLER AIR WILL PUSH INTO THE
REGION WITH SOME SHOWERS ON SUNDAY. HIGHS WILL BE IN THE 60S INTO
THE MIDDLE OF THE WEEK WITH 45-55 AT NIGHT. A SHORTWAVE WILL PASS
THROUGH THE REGION ON THURSDAY BRINGING A POSSIBILITY OF A
THUNDERSTORM.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 330 PM CDT THU AUG 20 2015
VFR CONDTIONS THIS AFTERNOON AT THE BRD/HIB/INL SITES. DLH TAF WILL
BE MVFR IMPROVING TO VFR BY LATE AFTERNOON. HYR TAF WILL STAY MVFR-
IFR THROUGH 00Z WHEN IT WILL IMPROVE TO VFR. OVERNIGHT...FOG WILL
LIKELY FORM DUE TO THE LIGHT WINDS/CLEAR SKIES/MOISTURE FROM THE
PAST DAYS RAINS AND WILL LOWER CONDTIONS TO MVFR-IFR THROUGH
12Z. CONDITIONS WILL IMPROVE TO VFR AT ALL SITES BY MID-MORNING.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 51 78 62 79 / 0 0 20 40
INL 47 82 60 80 / 20 20 20 70
BRD 52 82 64 81 / 0 0 20 70
HYR 48 79 62 81 / 0 10 10 10
ASX 47 80 61 84 / 0 0 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR LSZ148.
&&
$$
SHORT TERM...JJM
LONG TERM...STEWART
AVIATION...STEWART
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
143 PM EDT THU AUG 20 2015
.SYNOPSIS...
A COLD FRONT WILL MOVE SLOWLY ACROSS THE AREA TONIGHT INTO FRIDAY
CONTINUING A GOOD CHANCE FOR THUNDERSTORMS. SUNNY AND SEASONABLE
WEATHER IS EXPECTED FOR THE WEEKEND BEHIND THIS FRONT. WARMER AND
MORE HUMID AIR WILL RETURN NEXT WEEK AHEAD OF A COLD FRONT WHICH
WILL APPROACH ON TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 130 PM THURSDAY...SCATTERED THUNDERSTORMS APPROACHING
WILLIAMSBURG AND FLORENCE COUNTIES FROM THE WEST AT THIS
TIME...WHILE THE REST OF THE FORECAST AREA REMAINS QUIET...LIKELY
DUE TO EXTENSIVE CLOUD COVER THIS MORNING. FORECAST REMAINS ON
TRACK WITH SCATTERED CONVECTION PROGGED FOR THIS AFTERNOON
EVENING. PREVIOUS DISCUSSION FOLLOWS:
12Z CHS SOUNDING SHOULD BE REPRESENTATIVE OF THE AIRMASS TODAY.
MODIFIED FOR HEATING...EXPECT LI TO -4C AND MLCAPE TO 1400 J/KG.
PRECIPITABLE WATER JUST OVER 2 INCHES WILL COMBINE WITH
DESTABILIZATION THIS AFTERNOON TO PRODUCE AN ENVIRONMENT
SUPPORTIVE OF CONVECTION WITH THE POTENTIAL FOR LOCALLY HEAVY
DOWNPOURS. EXTENSIVE MORNING CLOUD COVER WILL LIMIT THE RATE OF
DESTABILIZATION AND COULD RESULT IN LESS COVERAGE THAN THE CURRENT
FORECAST INDICATES. LATEST HRRR DOES HINT AT THIS AS WELL. MAY
TWEAK THE POPS A BIT AND KEEP THE ENTIRE CWA IN THE 40-50 PERCENT
RANGE...BUT WILL ALSO HAVE TO WATCH A WEAKENING 500 MB SHORTWAVE
MOVING ACROSS UPSTATE SC THIS MORNING WHICH MAY ENHANCE THE
COVERAGE DURING THE AFTERNOON.
SCATTERED SHOWERS AND STORMS MAY LINGER THROUGH THE EVENING HOURS AS
THE COLD FRONT ENTERS THE EASTERN CAROLINAS. COOLING AT THE SURFACE
PLUS WARMING TEMPERATURES ALOFT SHOULD CAP OFF THE ATMOSPHERE TO
CONVECTION BY LATE EVENING WITH ONLY AN ISOLATED SHOWER OR TWO
POSSIBLE AFTER MIDNIGHT NEAR THE COAST. COMPARED TO MODEL SOLUTIONS
A FEW DAYS AGO THIS NOW LOOKS LIKE A CLEAN FRONTAL PASSAGE WITH
NORTHERLY SURFACE WINDS DEVELOPING OVERNIGHT ALL THE WAY DOWN TO THE
BEACHES.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...COLD FRONT WILL WAVER NEAR THE CWA ON
FRIDAY BEFORE WEAKENING WELL SOUTH ON SATURDAY. THIS CREATES AN
UNSETTLED FRIDAY...BUT VERY NICE WEATHER FOR THE WEEKEND.
WEAK SHORTWAVE RIDGING OVERHEAD TO START THE PERIOD WILL INHIBIT
RAPID PROGRESSION OF A COLD FRONT WHICH WILL BE NEAR THE COAST
FRIDAY MORNING. WHILE MID-LEVEL RIDGING WILL WEAKEN THROUGH THE
DAY...THIS FLOW ALOFT WILL IMPEDE THE FRONT ENOUGH THAT IT WILL
REMAIN DRAPED IN THE VICINITY...SLOWING EVEN FURTHER AS IT
COMBINES WITH THE EXPECTED SEA BREEZE DURING THE AFTN. THIS HYBRID
FRONT/SEA BREEZE WILL SERVE AS A FOCUS FOR CONVECTION FRIDAY
AFTN/EVE...AND SREF PROBS RISE ABOVE 90% FOR 6-HR PRECIP TOTALS
ABOVE 0.01 INCHES ACROSS THE EASTERN THIRD OF THE CWA. WILL RAMP
POP UPWARDS TO HIGH- CHC FOR THE COASTAL COUNTIES AND A BIT INLAND
FROM THERE...BUT MAINTAIN JUST SCHC/VERY LOW CHC WELL INLAND WHERE
DRIER AIR WILL BE WORKING IN BEHIND THE FRONT. LATE FRIDAY AND
INTO FRIDAY NIGHT AS THE SEA BREEZE WEAKENS AND THE MID-LEVEL
RIDGE DISSIPATES...THE FRONT WILL MAKE ITS FINAL PUSH AND BE
ALIGNED NE TO SW BUT SOUTH OF THE CWA BY SATURDAY MORNING. THIS
WILL LEAVE COOLER AND MUCH DRIER AIR IN PLACE SATURDAY...WITH
PWATS FALLING TO AROUND 1.25 INCHES AT THE END OF THE PERIOD. WILL
MAINTAIN JUST A VERY SCHC FOR SHOWERS FAR SE ZONES...ESPECIALLY THE
FIRST HALF OF THE DAY...BUT OTRW EXPECT A DRY AND PLEASANT
SATURDAY.
TEMPS BOTH AFTNS WILL BE SIMILAR THANKS TO THE LACK OF COOL
ADVECTION ASSOCIATED WITH THE FRONT. HIGHS FRIDAY WILL RANGE FROM
AROUND 88 AT THE COAST TO 92 WELL INLAND...AND JUST A DEGREE OR SO
COOLER ON SATURDAY. LOWS BOTH NIGHTS WILL DROP TO NEAR SEASONABLE
LEVELS...A DEGREE OR TWO EITHER SIDE OF 70...ALTHOUGH SATURDAY NIGHT
WILL BE THE COOLER OF THE TWO.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 300 AM THURSDAY...ATYPICAL LATE AUGUST WEATHER TO START THE
PERIOD...BUT FOR THE BETTER...AS BRIGHT SUNSHINE WILL COMBINE WITH
LOW HUMIDITY TO MAKE SUNDAY A BEAUTIFUL DAY ACROSS THE AREA WITH
TEMPS NEAR SEASONABLE NORMS. BY MONDAY...RETURN FLOW WILL REDEVELOP
LOCALLY AS HIGH PRESSURE SPINS OFFSHORE AND A COLD FRONT APPROACHES
FROM THE WEST. MONDAY WILL LIKELY FEATURE ABOVE CLIMO TEMPS BUT WITH
INCREASING HUMIDITY AND AT LEAST ISOLATED CONVECTION POTENTIAL. FOR
THE LATTER HALF OF THE EXTENDED...THAT COLD FRONT IS BEING DRIVEN
SOUTHWARD BY SOME VORT ENERGY ROTATING AROUND THE SOUTHERN PERIPHERY
OF AN ANOMALOUSLY STRONG UPPER LOW OVER SE CANADA...WILL LIKELY
STALL ACROSS THE AREA. THIS WILL CREATE A PERIOD OF UNSETTLED
WEATHER FOR TUE/WED WITH TEMPS AROUND CLIMO LEVELS FOR HIGHS...BUT
POTENTIALLY VERY WARM OVERNIGHT LOWS DUE TO CLOUD COVER.
&&
.AVIATION /17Z THURSDAY THROUGH MONDAY/...
AS OF 18Z...ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS EXPECT
THE REST OF TODAY AHEAD OF AN APPROACHING COLD FRONT POTENTIALLY
CREATING BRIEF PERIODS OF MVFR. OTHERWISE EXPECT VFR.
LATEST RADAR IMAGERY DEPICTS SHRA/TSRA ACTIVITY BEGINNING TO
INCREASE ACROSS THE AREA. THIS WILL CONTINUE THROUGH THIS AFTERNOON
AND INTO THE NIGHT HOURS AHEAD OF AN APPROACHING COLD FRONT. WEST-
SOUTHWEST WINDS WILL CONTINUE TO INCREASE OVER THE NEXT COUPLE OF
HOURS AS WELL...UP TO AROUND 12 KTS OR LESS. OVERNIGHT...ANY
LINGERING ACTIVITY WILL TAPER OFF AND WINDS WILL BECOME LIGHT OUT OF
THE WEST-NORTHWEST. LIGHT FOG IS POSSIBLE BEFORE DAYBREAK ON
FRIDAY...THUS HAVE INTRODUCED TEMPO GROUPS. FRIDAY MORNING...COLD
FRONT WILL BE PUSHING THROUGH THE AREA...WITH VFR BEHIND IT AND
LIGHT NORTHERLY WINDS THROUGH MIDDAY.
EXTENDED OUTLOOK...VFR WITH SCATTERED SHOWERS AND THUNDERSTORMS
THROUGH THE EXTENDED.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 130 PM THURSDAY...LATEST OBS SHOW LIGHT SOUTHWESTERLY WINDS
WITH SEAS IN THE 2 FT RANGE. FORECAST REMAINS IN GOOD SHAPE.
PREVIOUS DISCUSSION FOLLOWS:
A WEAK RIDGE OF HIGH PRESSURE EAST OF THE BAHAMAS WILL BREAK DOWN
TODAY AS A COLD FRONT APPROACHES FROM THE WEST. THIS FRONT IS
BEING DRIVEN EASTWARD BY LOW PRESSURE NEAR LAKE SUPERIOR. THE
FRONT SHOULD REACH THE BEACHES OF NORTH AND SOUTH CAROLINA AFTER
MIDNIGHT TONIGHT...PASSING WELL OFF THE COAST BEFORE DAYBREAK.
COMPARED TO MODEL SOLUTIONS JUST A COUPLE DAYS AGO THIS IS A MUCH
CLEANER AND MORE DRAMATIC FRONTAL PASSAGE...RATHER UNUSUAL FOR
MID-AUGUST.
SOUTHWEST WINDS AROUND 10 KNOTS TODAY WILL INCREASE TO 10-15 KT THIS
EVENING...BUT SHOULD VEER NORTHERLY AFTER MIDNIGHT AS THE FRONT
PUSHES THROUGH.
UNTIL THE FRONT ARRIVES...A WARM AND HUMID AIRMASS SHOULD GENERATE
SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AT THE COAST.
STEERING WINDS ARE FROM THE WEST...MEANING THESE STORMS WILL GET
BLOWN OUT PAST THE BEACHES AND SHOULD AFFECT THE NEARSHORE WATERS.
REDUCED VISIBILITY IN HEAVY RAINFALL...GUSTY WINDS...AND FREQUENT
LIGHTNING ARE ALL EXPECTED THIS AFTERNOON WITH THESE STORMS.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...COLD FRONT WILL BE NEAR THE COAST MUCH OF
FRIDAY AS IT WAVERS IN THE VICINITY THANKS TO MID-LEVEL RIDGING AND
WEAK STEERING FLOW. WITH THIS FRONT NEAR THE COASTAL WATERS ALL
DAY...WINDS WILL BE LIGHT BUT FEATURE A VARIETY OF DIRECTIONS...AND
THUS THE WAVE SPECTRUM WILL BE COMPRISED OF MANY WAVE GROUPS WITH
LOW AMPLITUDE...CREATING SEAS OF 1-2 FT. FRIDAY NIGHT THIS FRONT
WILL FINALLY GET A PUSH SOUTH AS HIGH PRESSURE EXPANDS FROM THE
NORTHEAST...AND THIS WILL CREATE NE WINDS AROUND 10 KTS ACROSS THE
WATERS...PERSISTING THROUGH SATURDAY. THIS MORE PRONOUNCED WIND
DIRECTION ALONG WITH HIGHER SPEEDS WILL DRIVE WAVE HEIGHTS SLIGHTLY
HIGHER...REACHING 1-3 FT FRIDAY NIGHT THROUGH SATURDAY NIGHT WITH A
NE WIND WAVE BECOMING PREDOMINANT.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 300 AM THURSDAY...LIGHT NORTH WINDS SUNDAY WILL GRADUALLY VEER
TO THE SW BY MONDAY AS RETURN FLOW REDEVELOPS LOCALLY. SPEEDS SUNDAY
WILL BE LESS THAN 10 KTS...BUT MAY INCREASE TO 10-15 KTS DURING
MONDAY AS THE GRADIENT TIGHTENS AHEAD OF A COLD FRONT APPROACHING
FROM THE NW. SEAS WILL BE NEARLY ENTIRELY WIND-WAVE DRIVEN THIS
PERIOD...RISING FROM 1-2 FT SUNDAY TO 2-3 FT MONDAY...ALTHOUGH SOME
LONG PERIOD BACK-SWELL ASSOCIATED WITH A LOW PRESSURE NEAR BERMUDA
MAY BEGIN TO ENTER THE SPECTRUM VERY LATE IN THE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...REK/TRA/CRM
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...SGL
MARINE...REK/TRA/JDW/CRM
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
702 PM EDT THU AUG 20 2015
.SYNOPSIS...
A COLD FRONT HAS MOVED EAST OF THE AREA WITH COOLER AND DRIER AIR
SETTLING OVER THE AREA BEHIND IT. A SURFACE AREA OF HIGH PRESSURE
TO OUR WEST WILL MOVE INTO THE AREA FRIDAY AND LINGER THROUGH THE
WEEKEND. THE NEXT CHANCE FOR RAIN WILL BE SUNDAY NIGHT INTO MONDAY
WHEN A COLD FRONT ARRIVES.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
UPPER TROUGH WILL LIFT ACROSS THE CENTRAL GREAT LAKES OVERNIGHT.
THERE WILL BE SOME INCREASED LIFT OVER THE LAKE AS THE COOLER AIR
ARRIVES IN THE WAKE OF THE TROUGH. THERE COULD BE A FEW SHOWERS
THAT DEVELOP FROM THE ERIE AREA NORTHWARD INTO NY STATE. HOWEVER
THE MAIN IMPACT WILL BE AN INCREASE OF CLOUD COVER FROM CLEVELAND
TO ERIE THROUGH THE EVENING.
PREVIOUS DISCUSSION...
THE WATER VAPOR SATELLITE IMAGERY DISTINCTLY DEFINES THE TROUGH
OVER THE UPPER LAKES AND THE DRIER AIR FILTERING INTO THE OHIO
VALLEY ALOFT. AT THE SURFACE HIGH PRESSURE OVER THE PLAINS WILL
SLIDE EAST OVERNIGHT AND LINGER OVER THE AIR INTO THE WEEKEND. DEW
POINTS HAVE DROPPED 10-15F SINCE THIS MORNING...WHICH WILL SUPPORT
NOTABLY COOLER TEMPERATURES OVERNIGHT. NCAR ENSEMBLES ALONG WITH
THE RUC ARE SUGGESTING DEW POINTS INTO THE UPPER 40S
OVERNIGHT...HOWEVER NOT SEEING ANY 40S UPSTREAM OR NEAR THE AREA
DESPITE A FAIR AMOUNT OF AFTERNOON MIXING. WITH DEW POINTS IN THE
LOW TO MID 50S...MOSTLY CLEAR SKIES...AND WINDS TAPERING OFF AFTER
DARK...WILL KEEP TEMPERATURES IN THE LOW TO MID 50S OVERNIGHT.
ONLY FLY IN THE OINTMENT WILL BE ANY POTENTIAL DEVELOPMENT OVER
THE LAKE AS THE H850 AND WATER TEMPERATURES DIFFER BY ABOUT 14C.
THE BEST CHANCE FOR ANYTHING TO DEVELOP WILL BE BETWEEN 06 AND 15Z
FRI...BUT AT THIS TIME WILL KEEP ONLY ISOLATED RAIN OVER THE
EASTERN PORTIONS OF THE LAKE AND NOT INTO ERIE PA.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS THE HIGH BUILDS OVERHEAD FRIDAY ANY LAKE ACTIVITY WILL BE SHUT
DOWN BY THE DRIER AIR AND THE SINKING INVERSION. LOOK FOR SUNNY
SKIES AND TEMPERATURES IN THE 70S. THE HIGH WILL SHIFT EAST ON
SATURDAY WHICH WILL SUPPORT SOME WEAK RETURN FLOW WHICH WILL
CONTINUE INTO SUNDAY. MEANWHILE THE NW FLOW ALOFT WILL TURN TO
THE SW WITH WARMER TEMPERATURES ADVECTING IN WITH H850 REACHING
12C WHICH WILL TRANSLATE INTO GRADUAL WARMING AT THE SURFACE. THE
NEXT CHANCE FOR PRECIPITATION WILL BE ASSOCIATED WITH ANOTHER MID
LEVEL TROUGH MOVING OUT OF THE ROCKIES. AN ASSOCIATED COLD FRONT
WILL REACH THE AREA SUNDAY NIGHT AND WITH WARMER/MOIST AIR AND AN
INCREASE IN THE LOW LEVEL JET CAN`T RULE OUT SOME THUNDERSTORMS.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
A COLD FRONT WILL BE MOVING THROUGH THE EASTERN EDGE OF THE AREA
MONDAY MORNING ALONG WITH A FEW LINGERING SHOWERS. COLD ADVECTION
WILL OVERSPREAD THE REGION IN THE WAKE OF THE COLD FRONT. THE
UPPER AIR PATTERN WILL EXHIBIT A LONG WAVE TROUGH OVER ONTARIO
EARLY IN THE EXTENDED WITH THIS FEATURE LIFTING FARTHER NORTH AND
ALLOWING A MORE ZONAL FLOW TO DEVELOP. BELOW NORMAL TEMPERATURES
ARE EXPECTED WITH GENERALLY DRY CONDITIONS BUT A FEW SHOWERS ARE
POSSIBLE WEDNESDAY AFTERNOON AND EVENING MAINLY OVER NORTHWEST PA
WHERE A MOIST CYCLONIC FLOW ALOFT ALONG WITH WELL MIXED ADIABATIC
CONDITIONS ARE EXPECTED.
CONDITIONS WILL WARM ON THURSDAY AND FRIDAY AS THE 850 MB
TEMPERATURES RISE TO MORE SEASONAL LEVELS AND MORE SUNSHINE
PREVAILS.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
COOL AIR ALOFT WILL SUPPORT LAKE EFFECT CLOUDS TONIGHT AND FRI
MORNING OVER LAKE ERIE. A TROUGH MOVING EAST ACROSS LAKE ERIE WILL
CAUSE THE MEAN LOW LEVEL WINDS TO VEER TO WNW WHICH WILL PROBABLY
PRODUCE SCT TO BKN CONDITIONS AT ERI LATE TONIGHT AND FRI MORNING.
HIGH PRESSURE PUSHES NE OVER OH FOR FRI AFTERNOON WHICH SHOULD
LEAD TO SLOW DISSIPATION OF THE LAKE EFFECT CLOUDS FRI AFTERNOON.
DAYTIME HEATING MAY PRODUCE SCT CU IN OTHER PARTS OF THE EAST BY
MIDDAY FRI BUT THIS CU WILL DISSIPATE BY EARLY EVENING.
WINDS WILL CONTINUE TO DIMINISH NEXT FEW HOURS AS TEMPS COOL AND
AIRMASS STABILIZES EXCEPT WINDS MAY CONTINUE TO RUN 8 TO 10 KNOTS AT
ERI FOR MUCH OF THE NIGHT.
OUTLOOK...NON VFR CONDITIONS POSSIBLE SUNDAY NIGHT WITH THE PASSAGE
OF A COLD FRONT AND POSSIBLE SHOWERS AND THUNDERSTORMS.
&&
.MARINE...
SMALL CRAFT CONDITIONS PREVAIL IN THE WAKE OF THE COLD
FRONT THAT HAS SWEPT EAST THROUGH THE REGION. A RATHER STRONG
PRESSURE GRADIENT FOR SUMMER ALONG WITH COLD ADVECTION ALOFT WILL
ALLOW MIXING OF HIGHER MOMENTUM AIR TO THE SURFACE. WITH 850 MB
TEMPERATURES EXPECTED TO DROP TO NEAR 10C AND LAKE SURFACE
TEMPERATURES FROM 22-24C... NEAR ADIABATIC LAPSE RATE IS EXPECTED
OVER THE LAKE WHICH WILL PERMIT DEEP MIXING AND STRONGER WINDS TO
PREVAIL. WILL CONTINUE WITH SMALL CRAFT ADVISORY THROUGH 08Z. IT MAY
NEED TO BE EXTENDED SLIGHTLY LONGER IN THE EASTERN HALF OF THE LAKE
WHERE THE STRONGER PRESSURE GRADIENT WILL LINGER.
HIGH PRESSURE WILL GRADUALLY BUILD SOUTH OF THE LAKE FRIDAY AND THEN
REMAIN OVER THE REGION INTO THE WEEKEND. WINDS WILL CONTINUE TO
DIMINISH FRIDAY AND BE LIGHT ON SATURDAY. SOUTHERLY WINDS WILL
INCREASE ON SUNDAY AS ANOTHER FRONTAL BOUNDARY APPROACHES WITH ITS
PASSAGE EXPECTED SUNDAY NIGHT. SMALL CRAFT CONDITIONS WILL LIKELY
DEVELOP IN THE WAKE OF THAT FRONTAL PASSAGE GIVEN THE COOLING ALOFT
DOWN TO JUST BELOW 10C AT 850 MB. WINDS WILL DECREASE ON TUESDAY AS
HIGH PRESSURE BUILDS INTO THE REGION.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT FRIDAY FOR LEZ142>149.
&&
$$
SYNOPSIS...JAMISON
NEAR TERM...JAMISON/MULLEN
SHORT TERM...JAMISON
LONG TERM...LAPLANTE
AVIATION...ADAMS
MARINE...LAPLANTE
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
334 PM EDT THU AUG 20 2015
.SYNOPSIS...
A COLD FRONT HAS MOVED EAST OF THE AREA WITH COOLER AND DRIER AIR
SETTLING OVER THE AREA BEHIND IT. A SURFACE AREA OF HIGH PRESSURE
TO OUR WEST WILL MOVE INTO THE AREA FRIDAY AND LINGER THROUGH THE
WEEKEND. THE NEXT CHANCE FOR RAIN WILL BE SUNDAY NIGHT INTO MONDAY
WHEN A COLD FRONT ARRIVES.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE WATER VAPOR SATELLITE IMAGERY DISTINCTLY DEFINES THE TROUGH
OVER THE UPPER LAKES AND THE DRIER AIR FILTERING INTO THE OHIO
VALLEY ALOFT. AT THE SURFACE HIGH PRESSURE OVER THE PLAINS WILL
SLIDE EAST OVERNIGHT AND LINGER OVER THE AIR INTO THE WEEKEND. DEW
POINTS HAVE DROPPED 10-15F SINCE THIS MORNING...WHICH WILL
SUPPORT NOTABLY COOLER TEMPERATURES OVERNIGHT. NCAR ENSEMBLES
ALONG WITH THE RUC ARE SUGGESTING DEW POINTS INTO THE UPPER 40S
OVERNIGHT...HOWEVER NOT SEEING ANY 40S UPSTREAM OR NEAR THE AREA
DESPITE A FAIR AMOUNT OF AFTERNOON MIXING. WITH DEW POINTS IN THE
LOW TO MID 50S...MOSTLY CLEAR SKIES...AND WINDS TAPERING OFF AFTER
DARK...WILL KEEP TEMPERATURES IN THE LOW TO MID 50S OVERNIGHT.
ONLY FLY IN THE OINTMENT WILL BE ANY POTENTIAL DEVELOPMENT OVER
THE LAKE AS THE H850 AND WATER TEMPERATURES DIFFER BY ABOUT 14C.
THE BEST CHANCE FOR ANYTHING TO DEVELOP WILL BE BETWEEN 06 AND 15Z
FRI...BUT AT THIS TIME WILL KEEP ONLY ISOLATED RAIN OVER THE
EASTERN PORTIONS OF THE LAKE AND NOT INTO ERIE PA.
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS THE HIGH BUILDS OVERHEAD FRIDAY ANY LAKE ACTIVITY WILL BE SHUT
DOWN BY THE DRIER AIR AND THE SINKING INVERSION. LOOK FOR SUNNY
SKIES AND TEMPERATURES IN THE 70S. THE HIGH WILL SHIFT EAST ON
SATURDAY WHICH WILL SUPPORT SOME WEAK RETURN FLOW WHICH WILL
CONTINUE INTO SUNDAY. MEANWHILE THE NW FLOW ALOFT WILL TURN TO
THE SW WITH WARMER TEMPERATURES ADVECTING IN WITH H850 REACHING
12C WHICH WILL TRANSLATE INTO GRADUAL WARMING AT THE SURFACE. THE
NEXT CHANCE FOR PRECIPITATION WILL BE ASSOCIATED WITH ANOTHER MID
LEVEL TROUGH MOVING OUT OF THE ROCKIES. AN ASSOCIATED COLD FRONT
WILL REACH THE AREA SUNDAY NIGHT AND WITH WARMER/MOIST AIR AND AN
INCREASE IN THE LOW LEVEL JET CAN`T RULE OUT SOME THUNDERSTORMS.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
A COLD FRONT WILL BE MOVING THROUGH THE EASTERN EDGE OF THE AREA
MONDAY MORNING ALONG WITH A FEW LINGERING SHOWERS. COLD ADVECTION
WILL OVERSPREAD THE REGION IN THE WAKE OF THE COLD FRONT. THE
UPPER AIR PATTERN WILL EXHIBIT A LONG WAVE TROUGH OVER ONTARIO
EARLY IN THE EXTENDED WITH THIS FEATURE LIFTING FARTHER NORTH AND
ALLOWING A MORE ZONAL FLOW TO DEVELOP. BELOW NORMAL TEMPERATURES
ARE EXPECTED WITH GENERALLY DRY CONDITIONS BUT A FEW SHOWERS ARE
POSSIBLE WEDNESDAY AFTERNOON AND EVENING MAINLY OVER NORTHWEST PA
WHERE A MOIST CYCLONIC FLOW ALOFT ALONG WITH WELL MIXED ADIABATIC
CONDITIONS ARE EXPECTED.
CONDITIONS WILL WARM ON THURSDAY AND FRIDAY AS THE 850 MB
TEMPERATURES RISE TO MORE SEASONAL LEVELS AND MORE SUNSHINE
PREVAILS.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
A COLD FRONT HAS MOVED EAST OF THE TAF SITES AND IS NOW IN
WESTERN NY AND PA. SCATTERED TO BROKEN CUMULUS DECK NEAR
3000-4000FT HAS DEVELOPED IN THE WAKE OF THE FRONT WITH SOMEWHAT
THICKER CLOUDS IN THE LEE OF LAKE MICHIGAN WHICH WILL SPREAD TO
NEAR TOL THIS AFTERNOON. SOUTHWEST WINDS OF 15-25 KNOTS WILL
DIMINISH TOWARD SUNSET AS DRIER AIR CONTINUES TO OVERSPREAD THE
REGION. DO NOT EXPECT FOG OVERNIGHT EXCEPT AT KYNG WHERE MORE
RAIN FELL AND THAT REGION IS MORE PRONE TO GET EARLY MORNING FOG
IN THE LATE SUMMER/EARLY AUTUMN MORNINGS. EXPECT VFR CONDITIONS
FRIDAY AND THROUGH THE WEEKEND.
OUTLOOK...
NON VFR CONDITIONS POSSIBLE SUNDAY NIGHT WITH THE
PASSAGE OF A COLD FRONT AND POSSIBLE SHOWERS AND THUNDERSTORMS.
&&
.MARINE...
SMALL CRAFT CONDITIONS PREVAIL IN THE WAKE OF THE COLD
FRONT THAT HAS SWEPT EAST THROUGH THE REGION. A RATHER STRONG
PRESSURE GRADIENT FOR SUMMER ALONG WITH COLD ADVECTION ALOFT WILL
ALLOW MIXING OF HIGHER MOMENTUM AIR TO THE SURFACE. WITH 850 MB
TEMPERATURES EXPECTED TO DROP TO NEAR 10C AND LAKE SURFACE
TEMPERATURES FROM 22-24C... NEAR ADIABATIC LAPSE RATE IS EXPECTED
OVER THE LAKE WHICH WILL PERMIT DEEP MIXING AND STRONGER WINDS TO
PREVAIL. WILL CONTINUE WITH SMALL CRAFT ADVISORY THROUGH 08Z. IT MAY
NEED TO BE EXTENDED SLIGHTLY LONGER IN THE EASTERN HALF OF THE LAKE
WHERE THE STRONGER PRESSURE GRADIENT WILL LINGER.
HIGH PRESSURE WILL GRADUALLY BUILD SOUTH OF THE LAKE FRIDAY AND THEN
REMAIN OVER THE REGION INTO THE WEEKEND. WINDS WILL CONTINUE TO
DIMINISH FRIDAY AND BE LIGHT ON SATURDAY. SOUTHERLY WINDS WILL
INCREASE ON SUNDAY AS ANOTHER FRONTAL BOUNDARY APPROACHES WITH ITS
PASSAGE EXPECTED SUNDAY NIGHT. SMALL CRAFT CONDITIONS WILL LIKELY
DEVELOP IN THE WAKE OF THAT FRONTAL PASSAGE GIVEN THE COOLING ALOFT
DOWN TO JUST BELOW 10C AT 850 MB. WINDS WILL DECREASE ON TUESDAY AS
HIGH PRESSURE BUILDS INTO THE REGION.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT FRIDAY FOR LEZ142>149.
&&
$$
SYNOPSIS...JAMISON
NEAR TERM...JAMISON
SHORT TERM...JAMISON
LONG TERM...LAPLANTE
AVIATION...LAPLANTE
MARINE...LAPLANTE
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
135 PM EDT THU AUG 20 2015
.SYNOPSIS...
A WEAK COLD FRONT WILL APPROACH THE AREA FROM THE WEST TODAY
BRINGING INCREASED CHANCES FOR SHOWERS AND THUNDERSTORMS. IN THE
FRONTS WAKE...SOME DRYING IS EXPECTED OVER THE WEEKEND. ANOTHER WEAK
FRONT APPROACHES THE CAROLINAS ON MONDAY WITH HIGH PRESSURE MOVING
OVER THE REGION BEHIND THE FRONT.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 135 PM...CONVECTION BEGINNING ACROSS THE CWFA AND WILL ONLY
INCREASE IN COVERAGE THRU THE REST OF THE AFTERNOON. GOING FCST HAS
THIS COVERED WITH ONLY MINOR UPDATES NEEDED FOR CURRENT CONDITIONS.
AS OF 1040 AM...SKIES CLEARING OUT FROM WEST TO EAST ACROSS THE
AREA. HOWEVER...CU BEGINNING TO DEVELOP IN THE CLEARED AREA AS
HEATING BEGINS. EXPECT THE CU TO CONTINUE TO INCREASE THRU THE DAY.
STILL LOOKS LIKE ANOTHER ROUND OF AT LEAST SCT CONVECTION TODAY
GIVEN THE UNSTABLE ATMOSPHERE AND THE COLD FRONT APPROACHING FROM
THE NW. OLDER CAM GUIDANCE WAS SUGGESTING POSSIBLY LESS COVERAGE
TODAY. HOWEVER...LATEST RUNS SHOW GOOD COVERAGE...BUT DO SUGGEST NE
GA AND THE UPSTATE MAY STILL HAVE LOWER COVERAGE THAN NC. WILL NOT
ADJUST POP FOR THE AFTERNOON...BUT DID SLOW DEVELOPMENT GIVEN THE
LACK OF CURRENT COVERAGE AND PREVIOUS QUICK ONSET. STILL EXPECT
MODERATE INSTABILITY WITH EFFECTIVE SHEAR APPROACHING MODERATE
LEVELS AS WELL. DCAPE WILL NOT BE EXCEPTIONALLY HIGH...BUT LOOKS TO
BE OVER 500 J/KG. THEREFORE...SEVERE STORMS POSSIBLE AGAIN. WITH PW
VALUES APPROACHING 2 INCHES...ISOLATED FLOODING WILL ALSO BE
POSSIBLE. HIGHS WILL BE TRICKY...ESPECIALLY GIVEN THE MORNING
CLEARING...BUT CURRENT VALUES SHUD BE CLOSE.
AS OF 630 AM THURSDAY...ONLY ISOLATED SHOWERS CONTINUE FOR THE
UPDATE...SO HAVE REDUCED POPS SIGNIFICANTLY THROUGH THE MORNING. AS
MENTIONED BELOW...HIRES GUIDANCE CONTINUES TO NOT BE VERY EXCITED
ABOUT CONVECTIVE POTENTIAL THIS AFTERNOON THOUGH SYNOPTIC MODELS
CONTINUE TO PAINT CONVECTIVE PRECIP ACROSS THE AREA. WITH THIS
UNCERTAINTY AND GIVEN PERSISTENCE TRENDS...MADE ONLY MINOR
ADJUSTMENTS TO AFTERNOON POPS.
AS OF 230 AM THURSDAY...BENIGN CONDITIONS AT AFD TIME...BUT THIS
AFTER QUITE AN EVENTFUL EVENING YESTERDAY. WARM RAIN PROCESSES AND
TRAINING CELLS RESULTED IN ANOTHER 5+ INCHES OF RAIN ACROSS PORTIONS
OF UNION COUNTY NC WHERE SOME SIGNIFICANT FLASH FLOODING WAS
REPORTED. GOOSE CREEK REMAINS HIGH WITH ONE POINT STILL IN FLOOD AT
AFD TIME.
ONTO THE FORECAST...DEEP UPPER TROUGH STRETCHING DOWN THE
MISSISSIPPI WILL BEGIN TO LIFT INTO THE GREAT LAKES AND SOUTHEAST
CANADA TODAY...WITH AN OCCLUDED COLD FRONT PUSHING TOWARD THE
SOUTHERN APPALACHIANS. THE SOUTHERN EDGE OF THE FRONT IS PROGGED TO
PUSH THROUGH THE FORECAST AREA TONIGHT BUT WASH OUT QUICKLY.
DEWPOINTS BY SUNRISE FRIDAY WILL ACTUALLY DROP INTO THE UPPER 60S
ACROSS THE UPSTATE WITH SOME UPPER 50S IN THE MOUNTAINS. WE WILL
ALSO SEE LOW TEMPERATURES A COUPLE OF DEGREES COOLER THAN WE HAVE
BEEN EXPERIENCING LATELY...BUT THE DECREASE IN DEWPOINTS WILL NOT BE
QUITE QUICK ENOUGH TO BRING LOWS DOWN TO SEASONAL NORMALS JUST YET.
ANOTHER WEAK SHORTWAVE DIVING TOWARD THE OHIO VALLEY TONIGHT...WITH
A FAIRLY POTENT VORT LOBE...WILL SERVE TO PULL UP ADDITIONAL
MOISTURE AS SURFACE PATTERN TRANSITIONS TO HIGH PRESSURE.
BIGGEST CONCERN OF THE NEAR TERM WILL BE CHANCE OF ADDITIONAL
CONVECTION TODAY. WITH THE APPROACH AND PASSAGE OF THE COLD FRONT...
CERTAINLY THERE IS ENOUGH SYNOPTIC FORCING...AND WITH PW VALUES
REMAINING GENERALLY AT OR ABOVE 2 INCHES...WE SHOULD CONTINUE TO SEE
FAIRLY EFFICIENT RAIN PRODUCERS. NOT GOOD NEWS FOR FOLKS THAT
EXPERIENCED SOME SIGNIFICANT RAINFALL AMOUNTS AND RESULTING FLASH
FLOODING LAST NIGHT. LUCKILY SBCAPE VALUES GENERALLY REMAIN BELOW
1000 J/KG SO CONVECTIVE INTENSITY SHOULD NOT BE QUITE AS BAD AS
YESTERDAY. ALL THAT SAID...HI-RES GUIDANCE NOT PARTICULARLY
IMPRESSED WITH CONVECTIVE POTENTIAL FOR THIS AFTERNOON. HRRR ONLY
HAS ISOLATED CONVECTION AT BEST EVEN THROUGH 20Z. WRF NMM AND ARW
REFLECTIVITY GUIDANCE ON PAR WITH THE HRRR. WITH THAT...KEPT POPS AT
CHANCE AT BEST ACROSS THE UPSTATE AND MOST OF THE NC PIEDMONT...WITH
LIKELIES IN THE MOUNTAINS. CONFIDENCE NOT PARTICULARLY HIGH SO WILL
HAVE TO MONITOR THROUGH THE DAY.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 310 AM EDT THURSDAY...THE SHORT TERM FCST PICKS UP AT 12Z ON
FRIDAY WITH THE UPPER TROF LIFTING NE OF THE GREAT LAKES AS HEIGHTS
BEGIN TO RISE OVER THE SE REGION. THIS PATTERN WILL PERSIST INTO THE
MEDIUM RANGE WITH VARIOUS LOBES OF SHORTWAVE ENERGY APPROACHING THE
CWFA FROM THE WEST OVER THE WEEKEND. IN ADDITION...ANOTHER COMPACT
UPPER TROF WILL DIG DOWN OVER THE US/CANADA BORDER OVER THE WEEKEND
AND MOVE ACROSS THE GREAT LAKES BY THE START OF THE MEDIUM RANGE.
ON FRIDAY...THE SFC HIGH GRADUALLY SLIDES EASTWARD AND THEN NE THRU
THE DAY AND EVENING WITH LOW LVL DRYING AS THE BNDY LAYER FLOW
BECOMES MORE NLY. THE GFS SOLUTION CONTINUES TO BE THE DRIEST MODEL
OVERALL WITH THE NAM BEING THE WETTEST. REGARDLESS OF MODEL
CHOICE...THE TREND IS FOR DRIER PROFILES AND LESS INFLUENCE FROM THE
GULF AS WE MOVE INTO SAT. ON SATURDAY...THE SFC HIGH SLIDES A BIT
FARTHER NE AND UP OVER NEW ENGLAND AS SOME WEAK WEDGING APPEARS TO
BRIEFLY DEVELOP OVER THE CAROLINAS. ANY WEDGING IS EXPECTED TO BE
SHORT LIVED WITH THE LOW LVL FLOW BECOMING WEAKER SAT AFTERNOON AND
EVENING. THE PERIOD ENDS EARLY SUN WITH THE NEXT COLD FRONT STILL
WELL TO OUR WEST AND MOSTLY LIGHT AND VRB FLOW OVER THE CWFA. AS FOR
THE SENSIBLE FCST...THE BEST CHANCES FOR ADDITIONAL PRECIP WILL BE
ON FRI WITH LOWER CHANCES FOR SAT AND SUN. MAX TEMPS WILL STRUGGLE
TO GET REACH CLIMO WHILE MIN TEMPS SHOULD START OUT ABOUT A CATEGORY
ABOVE AND COOL AROUND 2 TO 4 DEGREES THRU THE PERIOD.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 255 AM EDT THURSDAY...THE MEDIUM RANGE FCST BEGINS AT 12Z ON
SUNDAY WITH FLAT UPPER RIDGING OVER THE GULF OF MEX AND ANOTHER
UPPER TROF DIGGING DOWN OVER MINNESOTA AND THE WESTERN GREAT LAKES.
OVER THE REMAINDER OF THE PERIOD...THE LONG RANGE MODELS GRADUALLY
MOVE THE TROF EASTWARD AND EVENTUALLY LIFT IT NE OF NEW ENGLAND. THE
LATEST 00Z RUN OF THE GFS REMAINS FASTER WITH THE TROFS PROGRESSION
COMPARED TO THE ECMWF...HOWEVER THEY ARE MORE SIMILAR THAN BEFORE
WITH BOTH MODELS DEVELOPING A CLOSED LOW BY EARLY NEXT WEEK. THE
UPPER RIDGING WILL REAMPLIFY OVER THE CENTRAL CONUS IN THE TROFS
WAKE BY MID TO LATE NEXT WEEK WITH THE GFS STILL QUITE A BIT MORE
ROBUST WITH THE RIDGE. AT THE SFC...LINGERING HIGH PRESSURE WILL BE
IN PLACE OVER THE REGION ON SUNDAY. ANOTHER COLD FRONT WILL APPROACH
THE CWFA LATE SUN/EARLY MON AND MOVE ACROSS THE CWFA DURING THE DAY.
THE GFS CONTINUES TO BE FASTER AND A BIT DRIER OVERALL WITH THE
FROPA COMPARED TO THE ECMWF...YET BOTH MODELS ARE LOOKING PRETTY DRY
AT THIS POINT. ANOTHER HIGH WILL PUSH INTO THE REGION BEHIND THE
FRONT ON TUES AND LINGER THRU THE REMAINDER OF THE MEDIUM RANGE.
AS FOR THE SENSIBLE WX...NO SIGNIFICANT CHANGES WERE NEEDED WITH A
SLIGHT TO SOLID CHANCE POP EACH DAY AND TEMPS JUST ABOVE NORMAL FOR
LATE AUGUST.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AT KCLT...CONVECTION ALREADY DEVELOPING IN THE GENERAL AREA...SO
WILL KEEP THE TEMPO FOR TSRA AT 18Z-22Z. DID NOT ADD ANY MENTION
AFTER...BUT IT IS CERTAINLY POSSIBLE THEY COULD LINGER INTO THE
EARLY EVENING. OTHERWISE...FCST GENERALLY ON TRACK WITH DEVELOPING
LOW VFR CU WHICH BECOME STRATOCU DURING THE EVENING AND LINGER INTO
THE DAY FRIDAY. WITH THE COLD FRONT COMING THRU THIS EVENING...
WINDS WILL SHIFT FROM SW TO WNW THEN N THRU THE EVENING WITH NE WIND
FRI MORN. THIS WILL KEEP FOG AT BAY...AND LACK OF VERY LOW LEVEL
MOISTURE SHUD KEEP CIGS AT LOW VFR.
ELSEWHERE...SIMILAR TRENDS TO KCLT...BUT SLIGHTLY DIFFERENT WIND
SHIFT TIMING. ALSO...KAVL SEEMS TO HAVE THE BEST CHC OF ANY
RESTRICTIONS OVERNIGHT. HAVE GONE WITH MVFR FOG AND TEMPO IFR FOG
AND CIGS. COULD BE LESS IN THE WAY OF FOG AND MORE STRATUS...BUT AT
LEAST IFR LOOKS LIKELY. COULD BE ISOLATED TO LOW END SCT CONVECTION
DEVELOPING FRI...BUT CHC TOO LOW AND TIMING TOO UNCERTAIN TO INCLUDE.
OUTLOOK...DRY HIGH PRESSURE BUILDING IN FROM THE NORTH WILL LIMIT
RESTRICTIONS THROUGH THE WEEKEND.
CONFIDENCE TABLE...
17-23Z 23-05Z 05-11Z 11-12Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAVL LOW 57% LOW 55% HIGH 100% HIGH 83%
KHKY LOW 57% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 100% HIGH 100% HIGH 100% 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
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...RWH/TDP
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...RWH
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
248 PM CDT THU AUG 20 2015
.TONIGHT AND FRIDAY... FORECAST CONFIDENCE...HIGH
CLOUDS WILL SLOWLY CLEAR OUT DURING THE EVENING AND OVERNIGHT HOURS
AS A 500 MB SHORTWAVE TROUGH EVENTUALLY MAKES ITS WAY OFF TO THE
NORTH AND EAST. NAM AND RAP BUFKIT SOUNDINGS INDICATE A FAIRLY DRY
PROFILE BY 06Z TONIGHT. OVERNIGHT CLEARING...ALONG WITH CALMER
WINDS...WILL LEAD TO SOME DECENT ADIABATIC COOLING. LOWS TONIGHT
LOOK TO REACH PRIMARILY INTO THE LOWER TO MID 50S ACROSS SOUTHERN
WISCONSIN...WITH SOME ISOLATED LOCATIONS REACHING INTO THE UPPER
40S.
ONCE THE SHORTWAVE MOVES OFF TO THE EAST...A MORE ZONAL MID-LEVEL
FLOW WILL MOVE INTO THE REGION...KEEPING CONDITIONS QUIET. A PUSH OF
FEW TO SCATTERED LOW-LEVEL CLOUDS COULD APPEAR BY SUNRISE FRIDAY AS
A SURGE OF LOW-LEVEL MOISTURE MAKES ITS WAY INTO THE REGION.
ADDITIONALLY...SOME PATCHY FOG IS POSSIBLE ALONG THE WISCONSIN RIVER
VALLEY DURING THE EARLY MORNING HOURS FRIDAY. EXPECT QUIET
CONDITIONS DURING THE DAY FRIDAY AS NEGATIVE VORTICITY ADVECTION AND
SFC HIGH PRESSURE WILL BE IN CONTROL OVER THE REGION. SSW WINDS WILL
BECOME GUSTY AGAIN DURING THE DAY FRIDAY...ALTHOUGH NOT AS STRONG AS
WINDS FROM THURSDAY.
.FRIDAY NIGHT AND SATURDAY...FORECAST CONFIDENCE IS HIGH.
HIGH PRESSURE WILL REMAIN ANCHORED OVER THE EASTERN GREAT
LAKES...KEEPING US DRY THROUGH SATURDAY. WE SHOULD SEE SOME
RADIATIVE COOLING FRIDAY NIGHT...BUT IT WILL BE TEMPERED BY SOME
DECENT WINDS AND MIXING JUST ABOVE THE BOUNDARY LAYER. A TROUGH OF
LOW PRESSURE AND IS ASSOCIATED COLD FRONT WILL APPROACH THE REGION
ON SATURDAY...TIGHTENING UP THE PRESSURE GRADIENT ACROSS THE
FORECAST AREA. LOOK FOR SOUTHERLY WINDS TO INCREASE AND BECOME
QUITE GUSTY IN THE AFTERNOON. TEMPS SHOULD CLIMB INTO THE LOWER
AND MID 80S.
.SATURDAY NIGHT AND SUNDAY...FORECAST CONFIDENCE IS MEDIUM.
THE TROUGH/CDFNT TO THE WEST WILL PUSH INTO SOUTHERN WISCONSIN
AFTER MIDNIGHT SATURDAY NIGHT. THE MODELS SHOW BETTER SUPPORT
THROUGH A DEEP LAYER UPSTREAM...BUT IT WEAKENS AS THE SFC TROUGH
MOVES IN. GIVEN THE LATE TIMING OF THE TROUGH ARRIVAL AND THE
WEAKENING SUPPORT...I/LL BE SOMEWHAT CONSERVATIVE IN PRECIP
CHANCES AS IT TRACKS EAST THROUGH SUNDAY MORNING. THE BEST CHANCE
FOR RAIN WILL BE WEST AND NORTH OF MADISON LATE SATURDAY NIGHT
INTO SUNDAY MORNING. WEAKER CHANCES ALONG THE WI/IL BORDER AND THE
SOUTHEAST.
THE TROUGH AND CDFNT WILL EXIT EASTERN WISCONSIN DURING THE EARLY
AFTERNOON WITH COOLER AND DRIER AIR MOVING RIGHT BACK IN.
.MONDAY THROUGH THURSDAY...FORECAST CONFIDENCE IS HIGH.
BIG CANADIAN HIGH PRESSURE BUILDS IN FOR MUCH OF NEXT WEEK. EXPECT
DRY CONDITIONS WITH HIGHS IN THE 70S AND LOWS IN THE 50S. WE MIGHT
SEE ANOTHER TROUGH APPROACH LATE IN THE WEEK FOR A CHANCE OF RAIN.
LOTS OF MODEL UNCERTAINTY WITH THAT.
&&
.AVIATION/00Z TAFS/...
EXPECT VFR CIGS AND VSBYS TONIGHT AS AN AREA OF LOW PRESSURE SLOWLY
MAKES ITS WAY OFF TO THE NORTH AND EAST. THE LAST OF THE LOW- TO MID-
LEVEL CLOUDS WILL SLOWLY MOVE OUT BY THE EARLY EVENING. WINDS WILL
WEAKEN THIS EVENING AS SFC PRESSURE GRADIENT WEAKENS AND THE
BOUNDARY LAYER DECOUPLES. WINDS WILL BECOME MORE NORTHWESTERLY THIS
EVENING AS THE AREA OF LOW PRESSURE MOVES OFF TO THE EAST. THERE
COULD BE SOME PATCHY FOG DEVELOPING JUST WEST OF THE MSN TAF SITE IN
THE WISCONSIN RIVER VALLEY...BUT NOT FORECAST TO AFFECT THE MSN AREA
DIRECTLY. GUSTY WINDS WILL RETURN FROM THE SOUTH-SOUTHWEST DURING
THE DAY FRIDAY.
&&
.MARINE...
SMALL CRAFT ADVISORY FOR ALL NEARSHORE ZONES WILL CONTINUE UNTIL 00Z
TONIGHT AS WINDS WILL WEAKEN BY THAT TIME DUE TO WEAKENING SFC
PRESSURE GRADIENT. WINDS WILL EVENTUALLY VEER FROM THE WEST THIS
EVENING TO A MORE NORTHWESTERLY DIRECTION. NEARSHORE WINDS WILL
ABATE TONIGHT...BUT EXPECT GUSTY SSW WINDS TO RETURN DURING THE
DAY FRIDAY...ALTHOUGH NOT EXPECTED TO REACH SMALL CRAFT ADVISORY
CRITERIA.
&&
.BEACHES...
BREEZY WESTERLY WINDS WILL PERSIST UNTIL EARLY EVENING. WIND SPEEDS
WILL MOSTLY BE BETWEEN 15 TO 25 MPH. SWIM RISK WILL BE LOW DUE TO
MORE OF AN OFFSHORE WIND EXPECTED. GUSTY SOUTH-SOUTHWEST WINDS ARE
EXPECTED TO RETURN DURING THE DAY FRIDAY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR LMZ643>646.
&&
$$
TONIGHT/FRIDAY AND AVIATION/MARINE...JTS
FRIDAY NIGHT THROUGH THURSDAY...DAVIS