Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/30/13
AREA FORECAST DISCUSSION
NWS TUCSON AZ
910 PM MST TUE AUG 27 2013
.SYNOPSIS...ADDITIONAL MOISTURE WILL PUSH UP FROM THE SOUTH STARTING
WEDNESDAY...WITH OCCASIONAL IMPULSES IN THE SOUTHERLY FLOW BRINGING
A GOOD CHANCE OF THUNDERSTORMS THE SECOND HALF OF THE WEEK.
&&
.DISCUSSION...KEMX WSR-88D DETECTED ISOLATED MOSTLY LESS THAN 40 DBZ
ECHOES ACROSS SWRN COCHISE COUNTY AT 0405Z. MOVEMENT OF THESE CELLS
WAS TO THE WEST AROUND 10 KTS. THE REST OF SE AZ WAS VOID OF PRECIP
ECHOES AT THIS TIME. IR SATELLITE IMAGERY INDICATED CLOUD TOPS
WARMING ACROSS WRN PIMA COUNTY. MID-LEVEL CLOUDS WERE EXPANDING IN
COVERAGE ACROSS MUCH OF COCHISE/SRN GRAHAM COUNTIES.
BASED ON RADAR TRENDS AS WELL AS SEVERAL RUC HRRR SOLUTIONS...HAVE
REDUCED POPS ACROSS MUCH OF SE AZ FOR THE REST OF TONIGHT. THE BEST
CHANCE FOR SHOWERS AND THUNDERSTORMS UNTIL AROUND MIDNIGHT WILL BE
NEAR THE INTERNATIONAL BORDER ADJACENT SWRN COCHISE AND SANTA CRUZ
COUNTIES. ISOLATED SHOWERS MAY MOVE INTO FAR SERN SECTIONS AROUND
DAYBREAK WED AS PER THE RUC HRRR SOLUTIONS.
OTHERWISE...EXPECT INCREASING MOISTURE ALONG WITH AN INCREASED
CHANCE OF SHOWERS/TSTMS STARTING WED. PLEASE REFER TO THE PREVIOUS
DISCUSSION SECTION BELOW FOR ADDITIONAL DETAIL.
&&
.PREV DISCUSSION /209 PM MST TUE AUG 27 2013/...MODELS CONTINUE TO
SHOW THE LARGE AREA OF HIGH PRESSURE CENTERED OVER MISSOURI WITH A
TROUGH OFF THE COAST OF THE PACIFIC NORTHWEST. BETWEEN THESE TWO
SYSTEMS...SOUTH TO SOUTHEAST FLOW ALOFT RESIDES ACROSS SOUTHERN
ARIZONA. MODELS INDICATE THAT AN INVERTED TROUGH OVER NORTHEAST
MEXICO WILL LIFT TO THE NORTHWEST AND MAKE ITS WAY INTO EXTREME
SOUTHEAST ARIZONA BY EARLY WEDNESDAY MORNING AND WILL PUSH EVEN
FARTHER INTO THE STATE THROUGHOUT THE DAY ON THURSDAY AND INTO
WESTERN ARIZONA/SRN CALIFORNIA BY LATE FRIDAY/EARLY SATURDAY WITH
SOME TIMING DIFFERENCES DEPENDING ON MODEL CHOICE/PREFERENCE.
AT ANY RATE...THE MODELS DO SHOW A SIGNIFICANT INCREASE IN MOISTURE
WITH THIS SYSTEM WITH MODEL PW`S SHOWING VALUES ABOVE THE TWO INCH
MARK FOR THE WESTERN DESERTS OF PIMA COUNTY...MORE SPECIFICALLY NEAR
AJO AND ORGAN PIPE BY LATE WEDNESDAY AND INTO THURSDAY. FARTHER EAST
TOWARD TUCSON...VALUES NOT QUITE AS HIGH...BUT A RESPECTABLE 1.6 -
1.75 INCHES NOT OUT OF THE QUESTION. AS A RESULT OF THE FORCING
PROVIDED BY THE APPROACHING INVERTED TROUGH...ALONG WITH A
SUBSTANTIAL MOISTURE INCREASE...EXPECT TO SEE A CONSIDERABLE UPSWING
IN ACTIVITY BEGINNING WEDNESDAY AFTERNOON AND CONTINUING THROUGH
FRIDAY...ALTHOUGH FAVORED AREAS FOR CONVECTION WILL LIKELY BE ALONG
THE INTERNATIONAL BORDER...AS WELL AS AREAS TO THE WEST AND
NORTHWEST OF TUCSON...BUT ALSO THE WHITE MOUNTAINS OF NORTHERN
GREENLEE COUNTY.
AFTER FRIDAY EXPECTING A DOWNSWING IN ACTIVITY AS THE HIGH PRESSURE
SYSTEM OVER THE MID MISSISSIPPI RIVER VALLEY RETROGRADES TO A
POSITION OVER COLORADO/NEW MEXICO BY THIS WEEKEND. HOWEVER...STILL
ENOUGH LINGERING MOISTURE AROUND FOR A LOW GRADE MONSOON POP
FORECAST.
HIGHS WEDNESDAY GENERALLY NEAR NORMAL...THEN 5 TO 7 DEGS BELOW NORMAL
FOR THURSDAY AND FRIDAY. THEREAFTER...HIGHS NEAR OR SLIGHTLY BELOW
NORMAL EACH DAY. LOWS GENERALLY 2 TO 3 DEGS ABOVE NORMAL EACH
MORNING.
&&
.AVIATION...ISOLD -TSRA/-SHRA MOSTLY NEAR THE INTERNATIONAL BORDER
THE REST OF TONIGHT. SCT TSRA/SHRA WILL DEVELOP BY MID-MORNING
WEDNESDAY AND CONTINUE THRU WEDNESDAY EVENING OR 29/06Z. CLOUD BASES
MOSTLY ABOVE 12K FT AGL THE REST OF TONIGHT...THEN CLOUD DECKS
AROUND 7-11K FT AGL WEDNESDAY AND WEDNESDAY EVENING. SURFACE WIND
GENERALLY ELY/SELY 5-15 KTS WITH OCCASIONAL GUSTS TO 20 KTS WILL
PREVAIL THRU WEDNESDAY EVENING. AVIATION DISCUSSION NOT UPDATED
FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...EXPECT SCATTERED SHOWERS AND THUNDERSTORMS TO
CONTINUE INTO EARLY NEXT WEEK. GUSTY AND ERRATIC WINDS WILL OCCUR
WITH THE STRONGER THUNDERSTORMS. 20-FOOT WINDS WILL BE EAST TO
SOUTHEAST AROUND 5 TO 15 MPH THROUGH THURSDAY. THEREAFTER...NORMAL
DIURNAL WIND TRENDS WILL RETURN BY THIS WEEKEND.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
DISCUSSION...FRANCIS
PREVIOUS DISCUSSION...MOLLERE
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
620 AM EDT WED AUG 28 2013
.SYNOPSIS...
WEAK LOW PRESSURE OVER THE LOWER GREAT LAKES WILL TURN SOUTHEASTWARD
AND IT SHOULD PASS OFF THE VIRGINIA COAST LATE TONIGHT. WEAK HIGH
PRESSURE FROM THE NORTHWEST AND NORTH IS ANTICIPATED TO FOLLOW FOR
THURSDAY THROUGH SATURDAY. A WARM FRONT APPROACHING FROM THE
SOUTHWEST WILL LIFT THROUGH OUR REGION ON SUNDAY OR SUNDAY NIGHT
WITH A COLD FRONT FROM THE NORTHWEST EXPECTED TO ARRIVE ON MONDAY
NIGHT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY THIS MORNING...ESTF UPDATE AT 630 AM LOWERED POPS NE NJ AND
THE NJ CWATERS TODAY. FCST SEEMS ON TRACK ATTM. GFS/UKMET/ECMWF
ARE THE DRIVERS OF THE FCST. LOWERED THE CHC OF THUNDER BY ONE
CATEGORY.
TODAY...LOOKING LIKE A HEAVY RAIN EVENT FOR PTNS SE PA THRU THE
DELMARVA OR SNJ VCNTY KRDG-KPHL-KACY SWWD WITH 21Z/27 SREF PROBS FOR
1 INCH OF RAIN...PWAT BUILDING TO 2.1 INCHES OVER DELMARVA...SLOW -
10 KT - NW-W STEERING CURRENTS AND A SHORT WAVE LIFTING MOISTURE
OVER A SHALLOW CONVERGENCE ZONE NEAR SFC LOW PRES SOMEWHERE OVER E
MD DE. WHILE SVR TSTMS ARE UNLIKELY DUE TO WEAK SHEAR AND TT UNDER
48C...GULLY WASHERS ARE LIKELY WITH KI IN THE MID 30S THIS AFTN
THERE...SWI NEAR -2 AND A NEAR 90F AIRMASS IN THE WARM SECTOR. ML
CAPE WILL BE NEAR 1400J WHERE AND WHEN ITS NOT INITIALLY NOT RAINING
DURING MIDDAY. LIGHT WIND.
THE 00Z/28 RGEM/GGEM LOOK TOO FAR NORTH WITH THEIR FCST QPF
BULLSEYES.
THIS FCST IS A 50 50 BLEND OF THE GFS/NAM ELEMENTS WITH SOME RGEM IN
THE SKYCOVER PTN OF THE FCST. NO SREF INPUT INTO THE POP BUT THE
NEAR TERM PTN OF THIS FCST HAS A RELIANCE ON THE RAP MODEL GUIDANCE
AS SEEN IN THE CONSTANTLY MODEL UPDATED COSPA PRODUCT.
HPCQPF 06Z GRIDS WERE USED...WHICH FORCED THE BOX WX TOOL WORDING OF
HEAVY RAIN POSSIBLE FROM JUST SW OF KPHL S AND WEST TODAY.
FOR THUNDER...USED THE KI 36 (BLENDED 00Z/28 NAM/GFS KI) FOR
THUNDER. THAT KEEPS THUNDER LIMITED INLAND.
WE DID REVIEW THE 00Z/28 SPCWRF FOR TIMING CONVECTION AND ALSO THE
NSSL WRF QPF FCST (TTN-CMAY AXIS WHICH LOOKS TOO FAR NE BUT ISOLATED
3 INCH AMTS).
NO FLASH FLOOD WATCH. HOURLY FFG OVER 2.5 INCHES AND 6 HRLY IS
GENERALLY OVER 4.5 INCHES. MY CONCERN WITH RESPECT TO FFG...CHESTER
COUNTY PA AND NEW CASTLE DE. HOWEVER THAT DOESNT RULE OUT OTHER
COUNTIES. ITS WHERE ANY TSTMS REPEAT OR ARE QSTNRY THIS AFTN.
CONFIDENCE: AVERAGE
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
LEFTOVER CONVECTION DURING THE EVENING...MAINLY TO THE S OF KPHL.
THEN FOG AND STRATUS OVERNIGHT WITH POTENTIAL FOR 1/4MI DENSE FOG IN
PLACES WITH LIGHT WIND AND CLEARING ALOFT LEAVING THE MOIST BL
EXPOSED TO SATURATION. USED THE UPS CROSSOVER TOOL FOR FOG AFTER
06Z.
CONFIDENCE: ABOVE AVERAGE.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
ALOFT...THE PERIOD STARTS OFF WITH A NORTHWEST FLOW. AS THE BIG
RIDGE TO OUR WEST BECOMES SUPPRESSED ON SATURDAY, THE FLOW OVER THE
MID-ATLANTIC BECOMES MORE WESTERLY. THE FLOW TURNS MORE
SOUTHWESTERLY ON MONDAY AND TUESDAY AS A TROF MOVES THROUGH.
AT THE SURFACE...WEAK HIGH PRESSURE WILL BE IN PLACE THURSDAY THROUGH
SATURDAY. A WARM WILL MOVE THROUGH ON SUNDAY. A COLD FRONT WILL
FOLLOW ON MONDAY NIGHT.
PRECIPITATION...LOTS OF SMALL POPS(20/30%) THROUGH SUNDAY WITH THE
HIGHEST POPS ACROSS THE I-95 CORRIDOR WESTWARD AND DURING THE
AFTERNOON AND EVENING. WITH A COLD FRONT APPROACHING ON MONDAY AND
MOVING THROUGH MONDAY NIGHT, POPS ARE EVENLY DISTRIBUTED.
EVEN THOUGH WEAK HIGH PRESSURE IS IN PLACE, MODELS HAVE BEEN PUSHING
PRECIP ACROSS THE INTERIOR LATE THIS WEEK AND INTO THE WEEKEND FOR A
COUPLE DAYS. WITH WEAK S/W`S MOVING ACROSS THE TOP OF US COMBINED
WITH AFTERNOON INSTABILITY AND SHALLOW MOISTURE CONVERGENCE, IT
SEEMS REASONABLE. THE ONLY REAL CHANGE I MADE IN THE GRIDS THIS
MORNING WAS TO FOCUS MORE ON THE INTERIOR. THOSE VISITING THE
BEACHES MAY NOT SEE A DROP. AND THOSE FURTHER INLAND, THE FORECAST
WILL SOUND WETTER THAN REALITY.
TEMPERATURES...AROUND NORMAL THROUGH MONDAY. SLIGHTLY BELOW NORMAL
ON TUESDAY.
&&
.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
EARLY THIS MORNING PRIOR TO 12Z...VFR WITH SCT-BKN CLOUDS AOA 5000
FT DEVELOPING. PATCHY MVFR OR IFR FOG POSSIBLE NEAR KMIV AND KABE.
TODAY AFTER 12Z...VFR CIGS. ANY MVFR MORNING FOG WILL BURN OFF BY
14Z. LIGHT WIND. SHOWERS AND SCT TSTMS EXPECTED MOST TAF SITES FOR
1-4 HOURS. MOST LIKELY AREA FOR TSTMS IS VCNTY KRDG- KPHL- KILG-
KMIV. THE 06Z TAFS HAVE 3SM MDT SHOWERS WHERE MY CONFIDENCE IS
GREATEST FOR CONVECTION BUT NO MENTION OF TSTM ATTM DESPITE MY
EXPECTATION THAT KRDG/KPHL/KILG WILL RECORD A TSTM TODAY.
CONFIDENCE ON DETAILS: AVERAGE.
TONIGHT...VFR CIGS OR MVFR CONDS IN FOG/SCT SHOWERS AND ISO TSTMS
DIMINISHING EARLY WITH IFR CONDS IN ST/FOG APPEARING LIKELY LATE
FOR MOST TAF SITES. 21Z/27 SREF PROBS FOR THIS IFR OCCURRENCE ARE
ABOUT 40-50 PCT FOCUSED ON KMIV-KPHL AXIS. CONFIDENCE ON CIGS/VSBY
EARLY IS BELOW AVG. CONFIDENCE ON SOME SORT OF IFR IN FOG/STRATUS
LATE IS ABOVE AVERAGE...MAINLY AFTER 06Z.
OUTLOOK...
THURSDAY...MAINLY VFR. THERE IS A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS ON THURSDAY AFTERNOON.
THURSDAY NIGHT...MAINLY VFR WITH LATE NIGHT AND EARLY MORNING
VISIBILITY RESTRICTIONS POSSIBLE.
FRIDAY...MAINLY VFR. THERE IS A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS ON THURSDAY AFTERNOON.
FRIDAY NIGHT...MAINLY VFR WITH LATE NIGHT AND EARLY MORNING
VISIBILITY RESTRICTIONS POSSIBLE.
SATURDAY THROUGH SUNDAY...MAINLY VFR WITH LATE NIGHT AND EARLY
MORNING VISIBILITY RESTRICTIONS POSSIBLE. THERE IS A CHANCE OF
MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS.
&&
.MARINE...
NO HEADLINES THROUGH TONIGHT.
ATLC SEAS WILL CONTINUE TO RUN AROUND 1-3 FEET.
LIGHT AND VARIABLE WINDS TREND SOUTHERLY OR SOUTHEASTERLY DURING
THE DAY THEN EVENTUALLY NE TONIGHT.
NE GUSTS 15-20 KT POSSIBLE S NJ AND DE COASTS NEAR DAYBREAK
THURSDAY.
OUTLOOK...
WEAK HIGH PRESSURE CAN BE EXPECTED THURSDAY THROUGH SATURDAY. A WARM
FRONT WILL MOVE ACROSS THE WATERS FROM THE SOUTHWEST ON SUNDAY. WIND
SPEEDS AND WAVE HEIGHTS ARE EXPECTED TO REMAIN BELOW THE SMALL CRAFT
ADVISORY CRITERIA THROUGH THE PERIOD.
&&
.RIP CURRENTS...
TODAY...LOW RISK DOES NOT MEAN NO RISK BUT ITS BEEN A LOW RISK
SUMMER IN OUR FCST AREA SINCE THE ATLANTIC TROPICAL BASIN HAS BEEN
NOTABLY QUIET...DESPITE A FEW NAMED STORMS THAT JUST HAVENT SENT
MUCH SWELL UP OUR WAY.
THURSDAY...CURRENTLY IS OUTLOOKED LOW RISK BUT IF NE WINDS AVG 20
KT ALONG THE DE COAST...THIS COULD RESULT IN A MDT RISK THERE WITH
A HIGHER THAN MODELED SWELL. SO THERE IS RISK UNCERTAINTY FOR THURSDAY.
FRIDAY THROUGH MONDAY OUTLOOK AS LOW RISK DAYS.
&&
.CLIMATE...
TODAY`S HIGH TEMPERATURE AT PHILADELPHIA INTERNATIONAL AIRPORT
THROUGH 500 PM WAS 89 DEGREES. THIS MATCHES THE HIGH TEMPERATURE
WHICH OCCURRED BACK ON THE 21ST.
IF THE TEMPERATURE AT PHILADELPHIA DOES NOT REACH 90 DEGREES THIS
MONTH, IT WILL BE THE FIRST AUGUST SINCE 1984 WITHOUT AT 90 DEGREE
READING. IT IS RATHER UNUSUAL FOR THERE NOT BE AT LEAST ONE 90
DEGREE READING AT PHILADELPHIA DURING THE MONTH OF AUGUST. IT HAS
HAPPENED ONLY 5 TIMES OVER THE PAST CENTURY, IN 1920, 1927, 1934,
1963 AND 1984.
THE MONTH OF AUGUST SHOULD END UP AVERAGING BETWEEN 1.6 AND 2
DEGREES BELOW AVG FOR PHILADELPHIA.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KRUZDLO
NEAR TERM...DRAG 619A
SHORT TERM...DRAG
LONG TERM...KRUZDLO
AVIATION...DRAG/KRUZDLO 619A
MARINE...DRAG/KRUZDLO 619A
RIP CURRENTS...
CLIMATE...619A
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
346 AM EDT WED AUG 28 2013
.SYNOPSIS...
WEAK LOW PRESSURE OVER THE LOWER GREAT LAKES WILL TURN SOUTHEASTWARD
AND IT SHOULD PASS OFF THE VIRGINIA COAST LATE TONIGHT. WEAK HIGH
PRESSURE FROM THE NORTHWEST AND NORTH IS ANTICIPATED TO FOLLOW FOR
THURSDAY THROUGH SATURDAY. A WARM FRONT APPROACHING FROM THE
SOUTHWEST WILL LIFT THROUGH OUR REGION ON SUNDAY OR SUNDAY NIGHT
WITH A COLD FRONT FROM THE NORTHWEST EXPECTED TO ARRIVE ON MONDAY
NIGHT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY THIS MORNING...ESTF UPDATE AT 1230 AM CONTINUED WITH THE 1115
PM TUESDAY UPDATE WITH A LITTLE FOG INTO NNJ WITH LESS
SKYCOVER...LIGHT WIND RADIATION COOLING CONDITION IN NJ.
ISOLATED SHOWERS NOW DEVELOPING AND ENTERING BERKS COUNTY TO THE NW
OF KRDG AT 305 AM.
TODAY...LOOKING LIKE A HEAVY RAIN EVENT FOR PTNS SE PA THRU THE
DELMARVA OR SNJ VCNTY KRDG-KPHL-KACY SWWD WITH 21Z/27 SREF PROBS FOR
1 INCH OF RAIN...PWAT BUILDING TO 2.1 INCHES OVER DELMARVA...SLOW -
10 KT - NW-W STEERING CURRENTS AND A SHORT WAVE LIFTING MOISTURE
OVER A SHALLOW CONVERGENCE ZONE NEAR SFC LOW PRES SOMEWHERE OVER E
MD DE. WHILE SVR TSTMS ARE UNLIKELY DUE TO WEAK SHEAR AND TT UNDER
48C...GULLY WASHERS ARE LIKELY WITH KI IN THE MID 30S THIS AFTN
THERE...SWI NEAR -2 AND A NEAR 90F AIRMASS IN THE WARM SECTOR. ML
CAPE WILL BE NEAR 1400J WHERE AND WHEN ITS NOT INITIALLY NOT RAINING
DURING MIDDAY. LIGHT WIND.
THE 00Z/28 RGEM/GGEM LOOK TOO FAR NORTH WITH THEIR FCST QPF
BULLSEYES.
THIS FCST IS A 50 50 BLEND OF THE GFS/NAM ELEMENTS WITH SOME RGEM IN
THE SKYCOVER PTN OF THE FCST. NO SREF INPUT INTO THE POP BUT THE
NEAR TERM PTN OF THIS FCST HAS A RELIANCE ON THE RAP MODEL GUIDANCE
AS SEEN IN THE CONSTANTLY MODEL UPDATED COSPA PRODUCT.
HPCQPF 06Z GRIDS WERE USED...WHICH FORCED THE BOX WX TOOL WORDING OF
HEAVY RAIN POSSIBLE FROM JUST SW OF KPHL S AND WEST TODAY.
FOR THUNDER...USED THE KI 36 (BLENDED 00Z/28 NAM/GFS KI) FOR
THUNDER. THAT KEEPS THUNDER LIMITED INLAND.
WE DID REVIEW THE 00Z/28 SPCWRF FOR TIMING CONVECTION AND ALSO THE
NSSL WRF QPF FCST (TTN-CMAY AXIS WHICH LOOKS TOO FAR NE BUT ISOLATED
3 INCH AMTS).
NO FLASH FLOOD WATCH. HOURLY FFG OVER 2.5 INCHES AND 6 HRLY IS
GENERALLY OVER 4.5 INCHES. MY CONCERN WITH RESPECT TO FFG...CHESTER
COUNTY PA AND NEW CASTLE DE. HOWEVER THAT DOESNT RULE OUT OTHER
COUNTIES. ITS WHERE ANY TSTMS REPEAT OR ARE QSTNRY THIS AFTN.
CONFIDENCE: AVERAGE
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
LEFTOVER CONVECTION DURING THE EVENING...MAINLY TO THE S OF KPHL.
THEN FOG AND STRATUS OVERNIGHT WITH POTENTIAL FOR 1/4MI DENSE FOG IN
PLACES WITH LIGHT WIND AND CLEARING ALOFT LEAVING THE MOIST BL
EXPOSED TO SATURATION. USED THE UPS CROSSOVER TOOL FOR FOG AFTER
06Z.
CONFIDENCE: ABOVE AVERAGE.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
ALOFT...THE PERIOD STARTS OFF WITH A NORTHWEST FLOW. AS THE BIG
RIDGE TO OUR WEST BECOMES SUPPRESSED ON SATURDAY, THE FLOW OVER THE
MID-ATLANTIC BECOMES MORE WESTERLY. THE FLOW TURNS MORE
SOUTHWESTERLY ON MONDAY AND TUESDAY AS A TROF MOVES THROUGH.
AT THE SURFACE...WEAK HIGH PRESSURE WILL BE IN PLACE THURSDAY THROUGH
SATURDAY. A WARM WILL MOVE THROUGH ON SUNDAY. A COLD FRONT WILL
FOLLOW ON MONDAY NIGHT.
PRECIPITATION...LOTS OF SMALL POPS(20/30%) THROUGH SUNDAY WITH THE
HIGHEST POPS ACROSS THE I-95 CORRIDOR WESTWARD AND DURING THE
AFTERNOON AND EVENING. WITH A COLD FRONT APPROACHING ON MONDAY AND
MOVING THROUGH MONDAY NIGHT, POPS ARE EVENLY DISTRIBUTED.
EVEN THOUGH WEAK HIGH PRESSURE IS IN PLACE, MODELS HAVE BEEN PUSHING
PRECIP ACROSS THE INTERIOR LATE THIS WEEK AND INTO THE WEEKEND FOR A
COUPLE DAYS. WITH WEAK S/W`S MOVING ACROSS THE TOP OF US COMBINED
WITH AFTERNOON INSTABILITY AND SHALLOW MOISTURE CONVERGENCE, IT
SEEMS REASONABLE. THE ONLY REAL CHANGE I MADE IN THE GRIDS THIS
MORNING WAS TO FOCUS MORE ON THE INTERIOR. THOSE VISITING THE
BEACHES MAY NOT SEE A DROP. AND THOSE FURTHER INLAND, THE FORECAST
WILL SOUND WETTER THAN REALITY.
TEMPERATURES...AROUND NORMAL THROUGH MONDAY. SLIGHTLY BELOW NORMAL
ON TUESDAY.
&&
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
EARLY THIS MORNING PRIOR TO 12Z...VFR WITH SCT-BKN CLOUDS AOA 5000
FT DEVELOPING. PATCHY MVFR OR IFR FOG POSSIBLE NEW JERSEY WHERE BEST
RADIATIONAL COOLING. SHOWERS DEVELOPING VCNTY KRDG AROUND 0715Z.
LIGHT WIND. CONFIDENCE: AVERAGE
TODAY AFTER 12Z...VFR CIGS OVERSPREADING THE AREA. ANY MORNING
FOG WILL BURN OFF BY 14Z. LIGHT WIND. SHOWERS AND SCT TSTMS
EXPECTED MOST TAF SITES FOR 1-4 HOURS. MOST LIKELY AREA FOR TSTMS
IS VCNTY KRDG-KPHL-KILG-KMIV. THE 06Z TAFS HAVE 3SM MDT SHOWERS
WHERE MY CONFIDENCE IS GREATEST FOR CONVECTION BUT NO MENTION OF
TSTM ATTM DESPITE MY EXPECTATION THAT KRDG/KPHL/KILG WILL RECORD A
TSTM TODAY. CONFIDENCE ON DETAILS: AVERAGE.
TONIGHT...VFR CIGS OR MVFR CONDS IN FOG/SCT SHOWERS AND ISO TSTMS
DIMINISHING EARLY WITH IFR CONDS IN ST/FOG APPEARING LIKELY LATE
FOR MOST TAF SITES. 21Z/27 SREF PROBS FOR THIS IFR OCCURRENCE ARE
ABOUT 40-50 PCT FOCUSED ON KMIV-KPHL AXIS. CONFIDENCE ON CIGS/VSBY
EARLY IS BELOW AVG. CONFIDENCE ON SOME SORT OF IFR IN FOG/STRATUS
LATE .. AFTER 06Z...IS ABOVE AVERAGE.
OUTLOOK...
THURSDAY...MAINLY VFR. THERE IS A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS ON THURSDAY AFTERNOON.
THURSDAY NIGHT...MAINLY VFR WITH LATE NIGHT AND EARLY MORNING
VISIBILITY RESTRICTIONS POSSIBLE.
FRIDAY...MAINLY VFR. THERE IS A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS ON THURSDAY AFTERNOON.
FRIDAY NIGHT...MAINLY VFR WITH LATE NIGHT AND EARLY MORNING
VISIBILITY RESTRICTIONS POSSIBLE.
SATURDAY THROUGH SUNDAY...MAINLY VFR WITH LATE NIGHT AND EARLY
MORNING VISIBILITY RESTRICTIONS POSSIBLE. THERE IS A CHANCE OF
MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS.
&&
.MARINE...
NO HEADLINES THROUGH TONIGHT.
ATLC SEAS WILL CONTINUE TO RUN AROUND 2-3 FEET.
LIGHT AND VARIABLE WINDS TREND SOUTHERLY OR SOUTHEASTERLY DURING
THE DAY THEN EVENTUALLY NE TONIGHT.
NE GUSTS 15-20 KT POSSIBLE S NJ AND DE COASTS NEAR DAYBREAK
THURSDAY.
OUTLOOK...
WEAK HIGH PRESSURE CAN BE EXPECTED THURSDAY THROUGH SATURDAY. A WARM
FRONT WILL MOVE ACROSS THE WATERS FROM THE SOUTHWEST ON SUNDAY. WIND
SPEEDS AND WAVE HEIGHTS ARE EXPECTED TO REMAIN BELOW THE SMALL CRAFT
ADVISORY CRITERIA THROUGH THE PERIOD.
&&
.RIP CURRENTS...
TODAY...LOW RISK DOES NOT MEAN NO RISK BUT ITS BEEN A LOW RISK
SUMMER IN OUR FCST AREA SINCE THE ATLANTIC TROPICAL BASIN HAS BEEN
NOTABLY QUIET...DESPITE A FEW NAMED STORMS THAT JUST HAVENT SENT
MUCH SWELL UP OUR WAY.
THURSDAY...CURRENTLY IS OUTLOOKED LOW RISK BUT IF NE WINDS AVG 20
KT ALONG THE DE COAST...THIS COULD RESULT IN A MDT RISK THERE WITH
A HIGHER THAN MODELED SWELL. SO THERE IS RISK UNCERTAINTY FOR THURSDAY.
FRIDAY THROUGH MONDAY OUTLOOK AS LOW RISK DAYS.
&&
.CLIMATE...
TODAY`S HIGH TEMPERATURE AT PHILADELPHIA INTERNATIONAL AIRPORT
THROUGH 500 PM WAS 89 DEGREES. THIS MATCHES THE HIGH TEMPERATURE
WHICH OCCURRED BACK ON THE 21ST.
IF THE TEMPERATURE AT PHILADELPHIA DOES NOT REACH 90 DEGREES THIS
MONTH, IT WILL BE THE FIRST AUGUST SINCE 1984 WITHOUT AT 90 DEGREE
READING. IT IS RATHER UNUSUAL FOR THERE NOT BE AT LEAST ONE 90
DEGREE READING AT PHILADELPHIA DURING THE MONTH OF AUGUST. IT HAS
HAPPENED ONLY 5 TIMES OVER THE PAST CENTURY, IN 1920, 1927, 1934,
1963 AND 1984.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KRUZDLO
NEAR TERM...DRAG
SHORT TERM...DRAG
LONG TERM...KRUZDLO
AVIATION...DRAG/KRUZDLO
MARINE...DRAG/KRUZDLO
RIP CURRENTS...DRAG
CLIMATE...IOVINO
AREA FORECAST DISCUSSION
NWS MIAMI FL
858 PM EDT THU AUG 29 2013
.UPDATE...
A FEW CHANGES WERE MADE TO THE SHORT TERM FORECAST...DUE TO THE
LACK OF ACTIVITY THIS AFTERNOON AND EVENING. THE ONLY AREA THAT
REMAINED ACTIVE WITH SOME SHOWERS AND THUNDERSTORMS WAS AROUND THE
LAKE...AND NOW A FEW SHOWERS DEVELOPED FROM OUTFLOW BOUNDARIES
COLLISIONS ACROSS INTERIOR MIAMI-DADE COUNTY. ALL THIS ACTIVITY
WILL DISSIPATE QUICKLY AS THE NIGHT PROGRESSES. CURRENT GUIDANCE
CONTINUES SHOWING THE STALLED UPPER LEVEL LOW OVER THE WESTERN
HALF OF SOUTH FLORIDA THROUGH THE WEEKEND. THEREFORE...SIMILAR
WEATHER CONDITIONS ARE EXPECTED THROUGH THE HOLIDAY WEEKEND.
&&
.PREV DISCUSSION... /ISSUED 802 PM EDT THU AUG 29 2013/
AVIATION...
ISOLATED SHRAS CONTINUE TO FORM ALONG WEAK REMNANT OUTFLOW
BOUNDARIES MAINLY ACROSS INTERIOR AREAS AND ARE NOT AFFECTING ANY
OF THE TAF SITES ATTM. THIS ACTIVITY IS EXPECTED TO DISSIPATE OVER
THE NEXT FEW HOURS. WINDS SHOULD THEN BECOME LIGHT AND VARIABLE
OVERNIGHT BEFORE BECOMING EASTERLY TOMORROW AFTERNOON AT AROUND 10
KTS. INTRODUCED VCSH AT ALL SITES AFTER 18Z TOMORROW AS THERE
SHOULD BE ENOUGH BOUNDARY LAYER MOISTURE TO PRODUCE A FEW SHRAS.
HOWEVER...NOT TOO CONFIDENT THAT SHRAS WILL DIRECTLY AFFECT TAF
SITES...BELIEVE MOST OF THE ACTIVITY SHOULD REMAIN ACROSS
INTERIOR AREAS.
PREV DISCUSSION... /ISSUED 308 PM EDT THU AUG 29 2013/
SYNOPSIS...
A WEAK SURFACE HIGH PRESSURE SYSTEM ACROSS THE AREA WILL PERSIST
THROUGH THE WEEKEND AS A LOW PRESSURE TROUGH NORTH OF THE AREA
WEAKENS THROUGH THE PERIOD.
SHORT TERM...THROUGH SATURDAY NIGHT.
UPPER LEVEL LOW ACROSS THE AREA HAS WEAKENED SINCE YESTERDAY
SQUEEZED BETWEEN A STRONG UPPER LEVEL RIDGE ACROSS THE MIDDLE PART
OF THE COUNTRY AND ANOTHER ONE JUST EAST OF THE BAHAMAS. THE LOW
ITSELF IS AT THE TAIL END OF AN UPPER LEVEL TROUGH OFF THE EAST
COAST OF THE US. SHORT RANGE MODEL CONSENSUS INDICATE THIS
FEATURE, AS WEAK AS IT IS, WILL DRIFT SOUTHWEST OVER THE NEXT DAY
OR SO AND THEM MOVE NORTH OF THE AREA BY LATE IN THE WEEKEND. THE
COMBINATION OF DRIER AIR WRAPPED AROUND THIS LOW ALONG WITH UPR
LEVEL CONVERGENCE AND FAIRLY UNIMPRESSIVE THERMODYNAMIC PROFILES
HAVE RESULTED IN SUPPRESSED CONVECTIVE ACTIVITY WITH THIS FEATURE.
NORMALLY IN THE SUMMER TIME THE INTRUSION OF THIS KIND OF FEATURE
WITH COOLER MID LEVEL TEMPS RESULTS IN FAIRLY ACTIVE CONVECTION.
FOR THE REST OF TODAY WE ARE STILL FORECASTING A CHANCE OF SHOWERS
AND STORMS BUT SOMEWHAT LIMITED IN COVERAGE. THERE IS STILL AN OFF
CHANCE OF A STRONG STORM WITH MAIN CONCERN BEING GUSTY WINDS AND
LIGHTNING. THIS IS CONSISTENT WITH BOTH HRRR AND LOCAL HIGH RES
MODELS.
FOR THE REMAINDER OF THE PERIOD THERE IS FAIRLY GOOD CONSENSUS
WITH UPR LEVEL RIDGE ACROSS THE MIDDLE SECTIONS OF THE COUNTRY
RETROGRADING AS AFOREMENTIONED UPPER LEVEL LOW MOVES WEST
SOUTHWEST. ALONG WITH THAT GLOBAL AND HIGH RES MODELS KEEP PWAT
LEVELS AROUND OR BELOW NORMAL. WITH FAIRLY UNIMPRESSIVE
THERMODYNAMIC PROFILES THIS CALLS FOR PERSISTENCE FOR NEXT COUPLE
DAYS WITH ROUTINE DIURNAL CONVECTION IN THE FORM OF SCATTERED
SHOWERS AND STORMS. GIVEN FAIRLY WEAK STORM MOTION VECTORS THERE
ARE ABOUT EQUAL CHANCES OF RAIN ON BOTH SOUTHWEST AND SOUTHEAST
FLORIDA WITH EMPHASIS ACROSS INTERIOR AS SEA AND LAKE BREEZES
REMAIN DOMINANT.
LONG TERM...SUNDAY THROUGH NEXT THURSDAY
WITH UPPER LEVEL LOW OUT OF THE AREA AND LARGE SCALE PATTERN WITH
RIDGING ON THE WEST, TROUGH ON THE EAST, AND RIDGE OF HIGH PRESSURE
AT LOW LEVELS PERSISTING ACROSS THE AREA A PERSISTENT PATTERN OF
DIURNAL SHOWERS AND THUNDERSTORMS IS FORECAST FOR THE ENTIRE
PERIOD WITH NO HIGHLIGHTS AT THIS TIME. TEMPS WILL REMAIN AROUND
NORMAL EXCEPT OVERNIGHT LOWS SLIGHTLY ABOVE NORMAL.
MARINE...
WITH RIDGE OF HIGH PRESSURE AT THE SURFACE IN CONTROL ACROSS THE
AREA THROUGH THE NEXT 5 DAYS OR SO WINDS ARE FORECAST TO REMAIN
BELOW 10 TO 15 KNOTS RANGE THROUGH THE PERIOD. SEAS ARE NOT
FORECAST TO EXCEED 1-3 FEET ACROSS THE ATLANTIC WATERS AND
GENERALLY LESS THAN 2 FEET ACROSS THE GULF WATERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 76 90 75 90 / 10 30 20 30
FORT LAUDERDALE 78 91 78 90 / 10 30 20 30
MIAMI 78 92 77 90 / 10 30 20 30
NAPLES 75 91 74 90 / 10 30 20 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...17/ERA
AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION
NWS MIAMI FL
802 PM EDT THU AUG 29 2013
.AVIATION...
ISOLATED SHRAS CONTINUE TO FORM ALONG WEAK REMNANT OUTFLOW
BOUNDARIES MAINLY ACROSS INTERIOR AREAS AND ARE NOT AFFECTING ANY
OF THE TAF SITES ATTM. THIS ACTIVITY IS EXPECTED TO DISSIPATE OVER
THE NEXT FEW HOURS. WINDS SHOULD THEN BECOME LIGHT AND VARIABLE
OVERNIGHT BEFORE BECOMING EASTERLY TOMORROW AFTERNOON AT AROUND 10
KTS. INTRODUCED VCSH AT ALL SITES AFTER 18Z TOMORROW AS THERE
SHOULD BE ENOUGH BOUNDARY LAYER MOISTURE TO PRODUCE A FEW SHRAS.
HOWEVER...NOT TOO CONFIDENT THAT SHRAS WILL DIRECTLY AFFECT TAF
SITES...BELIEVE MOST OF THE ACTIVITY SHOULD REMAIN ACROSS
INTERIOR AREAS.
&&
.PREV DISCUSSION... /ISSUED 308 PM EDT THU AUG 29 2013/
SYNOPSIS...
A WEAK SURFACE HIGH PRESSURE SYSTEM ACROSS THE AREA WILL PERSIST
THROUGH THE WEEKEND AS A LOW PRESSURE TROUGH NORTH OF THE AREA
WEAKENS THROUGH THE PERIOD.
SHORT TERM...THROUGH SATURDAY NIGHT.
UPPER LEVEL LOW ACROSS THE AREA HAS WEAKENED SINCE YESTERDAY
SQUEEZED BETWEEN A STRONG UPPER LEVEL RIDGE ACROSS THE MIDDLE PART
OF THE COUNTRY AND ANOTHER ONE JUST EAST OF THE BAHAMAS. THE LOW
ITSELF IS AT THE TAIL END OF AN UPPER LEVEL TROUGH OFF THE EAST
COAST OF THE US. SHORT RANGE MODEL CONSENSUS INDICATE THIS
FEATURE, AS WEAK AS IT IS, WILL DRIFT SOUTHWEST OVER THE NEXT DAY
OR SO AND THEM MOVE NORTH OF THE AREA BY LATE IN THE WEEKEND. THE
COMBINATION OF DRIER AIR WRAPPED AROUND THIS LOW ALONG WITH UPR
LEVEL CONVERGENCE AND FAIRLY UNIMPRESSIVE THERMODYNAMIC PROFILES
HAVE RESULTED IN SUPPRESSED CONVECTIVE ACTIVITY WITH THIS FEATURE.
NORMALLY IN THE SUMMER TIME THE INTRUSION OF THIS KIND OF FEATURE
WITH COOLER MID LEVEL TEMPS RESULTS IN FAIRLY ACTIVE CONVECTION.
FOR THE REST OF TODAY WE ARE STILL FORECASTING A CHANCE OF SHOWERS
AND STORMS BUT SOMEWHAT LIMITED IN COVERAGE. THERE IS STILL AN OFF
CHANCE OF A STRONG STORM WITH MAIN CONCERN BEING GUSTY WINDS AND
LIGHTNING. THIS IS CONSISTENT WITH BOTH HRRR AND LOCAL HIGH RES
MODELS.
FOR THE REMAINDER OF THE PERIOD THERE IS FAIRLY GOOD CONSENSUS
WITH UPR LEVEL RIDGE ACROSS THE MIDDLE SECTIONS OF THE COUNTRY
RETROGRADING AS AFOREMENTIONED UPPER LEVEL LOW MOVES WEST
SOUTHWEST. ALONG WITH THAT GLOBAL AND HIGH RES MODELS KEEP PWAT
LEVELS AROUND OR BELOW NORMAL. WITH FAIRLY UNIMPRESSIVE
THERMODYNAMIC PROFILES THIS CALLS FOR PERSISTENCE FOR NEXT COUPLE
DAYS WITH ROUTINE DIURNAL CONVECTION IN THE FORM OF SCATTERED
SHOWERS AND STORMS. GIVEN FAIRLY WEAK STORM MOTION VECTORS THERE
ARE ABOUT EQUAL CHANCES OF RAIN ON BOTH SOUTHWEST AND SOUTHEAST
FLORIDA WITH EMPHASIS ACROSS INTERIOR AS SEA AND LAKE BREEZES
REMAIN DOMINANT.
LONG TERM...SUNDAY THROUGH NEXT THURSDAY
WITH UPPER LEVEL LOW OUT OF THE AREA AND LARGE SCALE PATTERN WITH
RIDGING ON THE WEST, TROUGH ON THE EAST, AND RIDGE OF HIGH PRESSURE
AT LOW LEVELS PERSISTING ACROSS THE AREA A PERSISTENT PATTERN OF
DIURNAL SHOWERS AND THUNDERSTORMS IS FORECAST FOR THE ENTIRE
PERIOD WITH NO HIGHLIGHTS AT THIS TIME. TEMPS WILL REMAIN AROUND
NORMAL EXCEPT OVERNIGHT LOWS SLIGHTLY ABOVE NORMAL.
MARINE...
WITH RIDGE OF HIGH PRESSURE AT THE SURFACE IN CONTROL ACROSS THE
AREA THROUGH THE NEXT 5 DAYS OR SO WINDS ARE FORECAST TO REMAIN
BELOW 10 TO 15 KNOTS RANGE THROUGH THE PERIOD. SEAS ARE NOT
FORECAST TO EXCEED 1-3 FEET ACROSS THE ATLANTIC WATERS AND
GENERALLY LESS THAN 2 FEET ACROSS THE GULF WATERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 76 90 75 90 / 10 30 20 30
FORT LAUDERDALE 78 91 78 90 / 10 30 20 30
MIAMI 78 92 77 90 / 10 30 20 30
NAPLES 75 91 74 90 / 10 30 20 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...17/ERA
AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION...UPDATED
NWS MIAMI FL
125 AM EDT WED AUG 28 2013
.AVIATION...
THE WINDS WILL BE LIGHT AND VARIABLE THROUGH THE EARLY MORNING
HOURS BEFORE INCREASING TO 5 TO 10 KNOTS FROM THE EAST LATE THIS
MORNING INTO THIS AFTERNOON FOR MOST OF SOUTH FLORIDA TAF SITES.
THE ONLY EXCEPTION TO THIS IS AT KAPF TAF SITE WHERE THE WINDS
WILL BECOME WESTERLY AFTER 17Z TODAY...DUE TO THE WEST COAST SEA
BREEZE PUSHING INLAND.
THERE SHOULD BE SHOWERS AROUND LATE THIS MORNING INTO THIS
AFTERNOON OVER ALL OF THE TAF SITES ALONG WITH A FEW THUNDERSTORMS
MAINLY AFTER 18Z. HOWEVER...THE COVERAGE OF THE THUNDERSTORMS WILL
BE SMALL OVER THE TAF SITES. SO WILL ONLY CARRY VCSH AT THIS TIME
FOR ALL OF SOUTH FLORIDA TAF SITES. THE CEILING AND VIS WILL ALSO
REMAIN IN THE VFR CONDITIONS THROUGH THIS EVENING AT ALL OF THE
TAF SITES...DUE TO THE UNKNOWN TIMING OF THE SHOWERS AND
THUNDERSTORMS AT THE TAF SITES.
&&
.AVIATION...54/BNB
.PREV DISCUSSION... /ISSUED 827 PM EDT TUE AUG 27 2013/
UPDATE...
SHOWERS AND A FEW EMBEDDED THUNDERSTORMS ASSOCIATED WITH A
PERSISTENT UPPER LEVEL LOW ACROSS SOUTH FLORIDA CONTINUE MAINLY
ACROSS THE ATLANTIC AND GULF WATERS. LATEST HRRR DEPICTS DEEPER
MOISTURE SWINGING WEST ACROSS THE ATLANTIC WATERS AND INTO THE
EAST COAST OVERNIGHT WITH A WEAK SURFACE TROUGH IN PLACE. WILL
KEEP CHANCE POP OVERNIGHT FOR THE EAST COAST METRO AREAS.
AVIATION...
WEATHER OVER SOUTH FLORIDA WILL CONTINUE TO BE DOMINATED BY MAINLY
MID-LEVEL LOW PRESSURE CENTERED OVER FLORIDA STRAITS...WHICH WILL
DRIFT WESTWARD FOR NEXT 24-36 HOURS. THIS MEANS MOIST EASTERLY FLOW
WILL PREVAIL...AT SPEEDS OF 5 TO 10 KTS AT THE SURFACE. SCATTERED
SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED ACROSS EASTERN
TERMINALS EVEN DURING THE OVERNIGHT...THUS VCSH TAFS STARTING AT
2-4Z AND CONTINUING THROUGH TAF PERIOD. EXCEPTION IS NAPLES WHERE
POP IS AROUND 30 PERCENT FOR TONIGHT AND WEDNESDAY. TEMPO THUNDER
GROUP PLACED IN PBI TAF DUE TO CLUSTER OF STORMS APPROACHING FROM
ATLANTIC AT 0Z.
&&
PREV DISCUSSION... /ISSUED 254 PM EDT TUE AUG 27 2013/
DISCUSSION...
THE MODEL TRENDS THE LAST COUPLE OF DAYS HAVE EMPHASIZED A CUT-
OFF MID TO UPPER LEVEL LOW FORECAST TO LINGER ACROSS THE REGION
THROUGH THE EARLY PART OF THE WEEK AND THEN A DRYING TREND DURING
THAT PERIOD. HOWEVER...THE LATEST GUIDANCE CONTINUES TO SUGGEST
THAT THE MID TO UPPER LEVEL LOW WILL LIKELY CONTINUE THROUGH THE
REMAINDER OF THE WEEK AND POSSIBLY INTO THE WEEKEND. IN ADDITION
THE LATEST GUIDANCE SUGGESTS THAT THE DRYING TREND WILL BE DELAYED.
FOR TONIGHT...SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE
FORECAST TO CONTINUE MAINLY ACROSS THE SOUTHERN AND EASTERN
PORTIONS OF THE PENINSULA WITH THE MORE NUMEROUS ACTIVITY EXPECTED
ACROSS THE SOUTHERN PORTION OF THE PENINSULA AND ADJACENT GULF
AND ATLANTIC WATERS.
THE LOW LEVEL FLOW AT THE 850 HPA LEVEL IS FORECAST TO BECOME MORE
SOUTHERLY TONIGHT INTO WEDNESDAY AND WILL MAINTAIN DEEPER LAYERED
MOISTURE ACROSS THE REGION. FORECAST SOUNDINGS INDICATE FORECAST
PWAT AROUND 1.9 INCHES ON WEDNESDAY. THE LINGERING UPPER LEVEL LOW
AND COOLER MID LEVELS WILL CONTINUE TO ALLOW FOR A CHANCE OF
AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS ON WEDNESDAY. ON
THURSDAY AND FRIDAY THE UPPER LEVEL LOW IS FORECAST TO LINGER
ACROSS THE REGION AND WILL ALSO ADD TO THE UNCERTAINTY OF THE
FORECAST. ALTHOUGH MAINLY ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS ARE FORECAST THURSDAY AND FRIDAY...THERE WILL BE
SUFFICIENT LINGERING MOISTURE THAT MORE MORE WIDE SPREAD COVERAGE
IS POSSIBLE DEPENDING ON THE POSITION OF THE UPPER LOW. WILL HAVE TO
WAIT AND SEE HOW THE MODELS HANDLE THE EVOLUTION OF THE UPPER LOW
FOR THE LATER PART OF THE WEEK INTO THE WEEKEND.
MARINE...
A WEAK PRESSURE GRADIENT AND LIGHTER AND AT TIMES VARIABLE WINDS
TO 10 KNOTS OR LESS ARE FORECAST ACROSS THE REGIONAL WATERS
THROUGH MOST OF THE FORECAST PERIOD WITH MOSTLY TRANQUIL SEAS
FORECAST THROUGH THE FORECAST PERIOD.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 77 91 79 92 / 20 20 20 20
FORT LAUDERDALE 78 90 80 93 / 20 20 20 20
MIAMI 77 91 78 93 / 20 20 20 20
NAPLES 76 89 76 91 / 20 20 20 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...60/BD
AVIATION/RADAR...59/RM
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
745 PM EDT THU AUG 29 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE SOUTHWARD ACROSS SOUTH CAROLINA AND GEORGIA
TONIGHT. THE FRONT WILL BECOME NEARLY STATIONARY SOUTH OF THE AREA
FRIDAY. ANOTHER COLD FRONT COULD AFFECT THE AREA EARLY NEXT WEEK
WITH DRIER AND COOLER AIR IN ITS WAKE.
&&
.NEAR TERM /UNTIL 8 AM FRIDAY MORNING/...
A COLD FRONT WAS MOVING INTO THE MIDLANDS FROM THE NORTH THIS
EVENING. THE AIRMASS AHEAD OF THE FRONT WAS UNSTABLE WITH LIFTED
INDICES OF MINUS 4 TO MINUS 6...THOUGH THE HIGHEST INSTABILITIES
WERE OVER EASTERN MIDLANDS TO THE COAST AND ACROSS THE PIEDMONT.
BOTH THE RUC AND NAM MODELS INDICATE AND UPPER LEVEL DISTURBANCE
CROSS THE AREA TONIGHT IN NORTHERLY FLOW ALOFT. HAVE INCLUDED
SLIGHTLY HIGHER POPS THE EVENING. THERE IS DRY AIR ALOFT...SO A
STORM THAT GETS TALL ENOUGH COULD PRODUCE STRONG DOWN-BURST WINDS.
MODELS ARE IN GOOD AGREEMENT OVERNIGHT DROPPING THE FRONTAL
BOUNDARY TO THE SOUTH OF THE CSRA AND SLOWING IT DOWN...POSSIBLY
BECOMING STATIONARY FRIDAY ACROSS SOUTHERN GA. GUIDANCE
TEMPERATURES AND CURRENT TRENDS INDICATE THAT TEMPERATURES WILL
LIKELY FALL TO THE LOWER 70S.
&&
.SHORT TERM /8 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
MODELS ARE IN GOOD AGREEMENT DROPPING THE FRONTAL BOUNDARY
TO THE SOUTH OF THE FA AND SLOWING IT DOWN...BECOMING STATIONARY
LATE NEAR THE COAST FRIDAY. OTHERWISE...UPPER TROUGH ALONG THE
EAST COAST WITH RIDGE IN THE MIDWEST. SURFACE RIDGE EXTENDING INTO
THE REGION FROM OFF THE MID ATLANTIC COAST. WEAK INSTABILITY NOTED
FRIDAY ALONG WITH DRIER AIR ADVECTING IN BEHIND THE FRONT ACROSS
THE NORTHERN MIDLANDS. MOISTURE APPEARS SHALLOW AND MID LEVEL CAP.
ANY THUNDERSTORMS THAT DEVELOP MORE LIKELY ASSOCIATED WITH SEA
BREEZE OR POSSIBLY IN THE CSRA DUE TO WEAK CONVERGENCE NEAR OLD
FRONTAL BOUNDARY. MOS POPS LOWER THAN PREVIOUS RUNS...SO CUT POPS.
SHOULD BE SLIGHTLY COOLER FRIDAY BEHIND WEAK FRONT...UPPER 80S TO
AROUND 90 FOR HIGHS. OVERNIGHT LOWS IN THE UPPER 60S TO LOW 70S. UPPER
RIDGE OVER THE MIDWEST WILL BE RETROGRADING SATURDAY...TRIGGER FOR
CONVECTION STILL LACKING AND INSTABILITY REMAINS WEAK WITH MOISTURE
SHALLOW. MID LEVEL CAP AGAIN SHOULD LIMIT DEVELOPMENT.
AGAIN...THUNDERSTORMS MAINLY NEAR OLD FRONT...OR ASSOCIATED WITH
SEA BREEZE. CUT POPS FROM PREVIOUS FORECAST...TEMPERATURES NEAR
90. LOWS IN THE LOW 70S.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
UPPER TROUGH IN THE EAST AMPLIFYING BY LATE SUNDAY...INCREASING
MOISTURE/MORE WELL DEFINED SURFACE TROUGH AND RESULTING STRONGER
INSTABILITY SUGGESTS SCATTERED AFTERNOON THUNDERSTORMS SUNDAY AND
MONDAY. TEMPERATURES UPPER 80S. UPPER TROUGH AMPLIFIES TUESDAY AND
DRIVES A COLD FRONT THROUGH THE AREA... SLIGHTLY DRIER AIR MASS
WEDNESDAY BUT FRONT NEAR THE COAST. BY WEDNESDAY AND THURSDAY
EXPECT LOW CHANCE RAIN AND TEMPERATURES GENERALLY CLOSE TO
CLIMATOLOGY.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
FRONTAL BOUNDARY SHOWING UP ON REGIONAL RADARS IS ACROSS THE EASTERN
MIDLANDS...AND WILL CONTINUE TO PUSH OFF TO THE SOUTH AND WEST OVER
THE NEXT SEVERAL HOURS. BULK OF THE RAINFALL ASSOCIATED WITH THIS
FRONT APPEARS AS IF IT WILL TRACK JUST OFF TO THE EAST OF ALL TAF
SITES...WITH KOGB HAVING THE HIGHEST PROBABILITY OF GETTING
RAINFALL THE NEXT FEW HOURS. HIGHEST INSTABILITY IS OFF TO THE EAST
WHERE THE CURRENT STORMS ARE TRACKING. HAVE LEFT MENTION OF VCTS
OR TEMPO GROUP OUT OF THE TAFS AT THIS TIME AND WILL CONTINUE TO
MONITOR. WINDS WILL START OFF OUT OF THE NORTHWEST TO NORTH...AND
THEN WILL TURN TO THE NORTH TO NORTHEAST BEHIND THE FRONTAL PASSAGE.
MODELS STILL SHOWING A LOW LEVEL JET FORMING OVERNIGHT...WHICH
SHOULD HELP INHIBIT ANY WIDESPREAD FOG FORMATION. CAN NOT RULE OUT
MVFR VISIBILITIES OR CEILINGS TOWARDS MORNING THOUGH. ENSEMBLES
SHOW HIGHEST CHANCE FOR MVFR CEILINGS NEAR 12Z...AND HAVE TRENDED
TOWARDS SCATTERED CLOUDS AROUND 1.2KFT AROUND THAT TIME-FRAME. ALSO
INCLUDED A TEMPO GROUP FOR BROKEN CLOUD DECK FORMATION AROUND
SUNRISE. LATER IN THE DAY ON FRIDAY WINDS WILL CONTINUE TO BE FROM
THE NORTHEAST AROUND 5 TO 6 KNOTS AND VFR CONDITIONS WILL PREVAIL.
EXTENDED AVIATION OUTLOOK...POSSIBLE IFR/MVFR CONDITIONS FOR FOG
SATURDAY AND SUNDAY MORNINGS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1013 PM CDT THU AUG 29 2013
.DISCUSSION...
942 PM CDT
THE MAIN CHANGE TO THE GOING FORECAST WAS TO STRESS THE FOG A BIT
MORE OVERNIGHT INTO EARLY FRIDAY MORNING...ESPECIALLY FOR THE
SOUTHEAST HALF OF THE FORECAST AREA...AND ONCE AGAIN ALONG THE
LAKE MI SHORE NAMELY FOR OVERNIGHT.
THE BROAD AREA OF HIGH PRESSURE CENTERED TO OUR EAST CONTINUES TO
EVOLVE ITS WAY SOUTHEAST TOWARD THE MID-ATLANTIC. EARLIER FOG OVER
THE LAKEFRONT INCLUDING IN DOWNTOWN HAD BASICALLY DISSIPATED BY
7-7:30 PM. HOWEVER LATEST GOES FOG PRODUCT IS INDICATING A
RE-BLOSSOMING START OF FOG AND/OR STRATUS EAST OF CHICAGO ABOUT 25
MILES EAST OF CHICAGO. THE BOUNDARY LAYER HAS BEEN ABLE TO
DECOUPLE PER AMDAR SOUNDINGS AND SURFACE WIND OBS. LINGERING HIGH
DEW POINTS NEAR 70 AND LOW-LEVEL MIXING RATIOS AROUND 15 G/KG ARE
DRAPED ACROSS THE SOUTHERN AND WESTERN FORECAST AREA AND CLEAR
SKIES HAVE ALLOWED TEMPERATURES TO GET WITHIN A FEW DEGREES OF
THIS ALREADY AT A HANDFUL OF LOCATIONS.
WHILE THE PRESSURE GRADIENT WILL GRADUALLY BUILD IN FROM THE WEST
TONIGHT...MUCH OF THE EASTERN CWA SHOULD REMAIN DECOUPLED ENOUGH
FOR SURFACE WINDS TO REMAIN CALM. MODIFIED 00Z ILX SOUNDING AND
MODIFIED FORECAST SOUNDINGS FROM THE RAP AND NAM FOR CURRENT
CONDITIONS AT IKK/VPZ INDICATE PROFILES FAVORABLE FOR FOG BY
MIDNIGHT. HAVE BUMPED UP COVERAGE TO AREAS BUT THINK ANY DENSE FOG
WILL REMAIN PATCHY. AS FOR OVER THE LAKE...THE EXPANDING AREA EAST
OF CHICAGO WILL LIKELY ADVECT TOWARD THE IL SHORE AND POSSIBLY
EXPAND BACK TOWARD IN BEFORE THE RETURN FLOW SETTLES IN OVER THE
LAKE AFTER MIDNIGHT. GIVEN WHAT WAS SEEN EARLIER THURSDAY...SOME
OF THIS FOG COULD BE DENSE AS IT ROLLS INTO THE IL SHORE OVERNIGHT.
HAVE MADE ONLY SLIGHT TWEAKS TO MIN TEMPERATURES...WHICH PRIMARILY
LOOK ON TRACK.
EARLY LOOK AT 00Z NAM CONTINUES TO SHOW THE LIKELIHOOD OF
SCATTERED CONVECTION ON FRI AFTERNOON THROUGH ESPECIALLY MID-
EVE...WITH GREATEST CHANCES IN NORTHEAST IL/NORTHWEST
IN...INCLUDING ALL OF CHICAGOLAND. HIGH CAPE/MODEST SHEAR
ENVIRONMENT...ALONG WITH A SLIGHTLY MORE FAVORABLE VORT PATH THAN
PREV RUN...WOULD ALL STILL SUPPORT AN ISOLATED SEVERE THREAT.
MTF
//PREV DISCUSSION...
309 PM CDT
THE MAIN FORECAST CONCERNS WILL BE THE CHANCES AND TIMING OF
THUNDERSTORM ACTIVITY LATE FRIDAY AND FRIDAY NIGHT. TEMPERATURES ARE
ALSO A SIGNIFICANT FOCUS AS IT APPEARS WE WILL BE ON A SEE SAW OVER
THE NEXT SEVERAL DAYS AS SEVERAL COLD FRONTS TAKE AIM ON THE AREA.
THE LAST BIT OF LOW CLOUDS FROM THIS MORNING ARE FINALLY
DISSIPATING JUST WEST OF KPNT EARLY THIS AFTERNOON...SETTING UP
MOSTLY SUNNY SKIES ACROSS THE REGION. HOWEVER...LOW CLOUDS AND FOG
CONTINUE TO FESTER ACROSS THE SOUTHEASTERN TIP OF LAKE
MICHIGAN...JUST OFF THE COOK COUNTY ILLINOIS AND LAKE AND PORTER
COUNTY INDIANA SHORES. ALTHOUGH THIS ACTIVITY HAS REMAINED MAINLY
OVER THE WATERS OF LAKE MICHIGAN THROUGH THE DAY...IT IS POSSIBLY
THAT SOME OF THIS FOG COULD ROLL IN ACROSS THE SHORES EARLY THIS
EVENING. THEREFORE...I ADDED THE MENTION OF AREAS OF FOG FOR THE
IMMEDIATE SHORE LINE. IF THIS FOG DOES MOVE ONSHORE...IT WILL LIKELY
BE DENSE...SO CONDITIONS WILL NEED TO BE MONITORED THIS EVENING. THE
GOOD NEWS IS THAT THE WINDS SHOULD SWITCH OUT OF THE SOUTH OVERNIGHT
TONIGHT...WHICH SHOULD ALLOW ANY FOG TO MOVE BACK OUT OVER THE LAKE
LATER TONIGHT.
THE MAIN WEATHER DISTURBANCE OF INTEREST LATER FRIDAY/FRIDAY
NIGHT...IS CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING ACROSS
NORTH DAKOTA...ALONG THE NORTHERN PERIPHERY OF THE UPPER RIDGE
ENCOMPASSING THE PLAINS. THIS FEATURE IS EXPECTED TO PRODUCE
CONVECTION WELL NORTH OF THE AREA TONIGHT. HOWEVER...A SURFACE COLD
FRONT IS FORECAST TO DROP SOUTHWARD ACROSS WISCONSIN THROUGH THE DAY
ON FRIDAY. TO THE SOUTH OF THIS FRONT...A THERMAL RIDGE WILL SHIFT
EASTWARD ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA....SETTING UP ANOTHER DAY OF HOT AND HUMID CONDITIONS. THIS
SHOULD ALLOW TEMPERATURES TO AGAIN TOP OUT IN THE LOWER TO MIDDLE
90S ACROSS THE AREA ON FRIDAY...WITH HEAT INDICES NEAR 100 DEGREES.
DURING THE LATE AFTERNOON AND EVENING HOURS...THIS COLD FRONT WILL
BEGIN TO MOVE OVER NORTHERN ILLINOIS. IT APPEARS THAT SCATTERED
CONVECTIVE INITIATION WILL OCCUR ACROSS SOUTHERN WISCONSIN BY MID
AFTERNOON...THEN PROGRESS SOUTHEASTWARD ACROSS NORTHERN ILLINOIS
LATER IN THE AFTERNOON AND INTO THE EVENING. IT APPEARS THERE WILL
BE A THREAT FOR SOME STRONG TO SEVERE STORMS WITH THIS ACTIVITY.
HOWEVER...DEEP LAYER SHEAR LOOKS TO REMAIN RATHER MARGINAL (20 TO 30
KT) FOR ORGANIZED CONVECTION. IN SPITE OF THIS...MODEL SOUNDINGS
INDICATE STEEP MID LEVEL LAPS RATES AND PROFILES SUPPORTIVE OF SOME
STRONG WIND GUSTS/MICRO-BURST...SO THE THREAT OF SEVERE STORMS IS NOT
ZERO. IN ADDITION...THE HIGH THETA-E AIR MASS AHEAD OF THE
APPROACHING FRONT...WITH PWATS EXPECTED TO BE AROUND 1.9
INCHES...COULD SUPPORT SOME TORRENTIAL DOWNPOURS IN THE STRONGEST
STORMS. THESE STORMS SHOULD DROP SOUTH AND EASTWARD ACROSS THE AREA
THROUGH THE EVENING. SOME THIS ACTIVITY COULD LINGER OVERNIGHT INTO
EARLY SATURDAY ACROSS MY FAR SOUTHERN COUNTIES.
SOME COOLER AIR ARRIVES ACROSS THE AREA FOR SATURDAY IN THE WAKE OF
THIS FRONTAL ZONE. THIS SHOULD DROP TEMPERATURES BACK INTO THE MID
TO UPPER 80S FOR SATURDAY.
A SECOND SYSTEM LOOKS TO TOP THE RIDGE AXIS ACROSS THE PLAINS...AND
THEN DIG SOUTHEASTWARD OVER THE GREAT LAKES LATE SUNDAY AND INTO
MONDAY. THIS SYSTEM LOOKS TO DRIVE ANOTHER...STRONGER COLD FRONT
ACROSS THE AREA DURING THE DAY ON SUNDAY. THIS APPEARS TO BE ANOTHER
DECENT SHOT FOR SOME SHOWERS AND THUNDERSTORMS INTO SUNDAY EVENING.
ONCE THIS FRONT PASSES BY...MUCH COOLER AND DRIER AIR WILL MOVE
ACROSS THE AREA FOR MONDAY AS A SURFACE HIGH BUILDS EASTWARD ACROSS
THE MID MISSISSIPPI RIVER VALLEY. THIS SHOULD RESULT IN HIGHS BACK
INTO THE 70S FOR MONDAY AND TUESDAY.
TEMPERATURES LOOK TO MODERATE BACK INTO THE 80S BY WEDNESDAY AS THE
THERMAL RIDGE SHIFTS EASTWARD ALONG THE BACK SIDE OF THE SURFACE
HIGH. HOWEVER...THE OVERALL PATTERN LOOKS TO REMAIN DRY ACROSS THE
REGION THROUGH THE MIDDLE OF NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* LOW POTENTIAL FOR HIGH END MVFR VIS IN BR HZ OVERNIGHT INTO
EARLY FRI MORNING.
* CHANCE OF SHRA/TSRA LATER FRI AFTERNOON TIL MID FRI EVENING.
* COLD FRONT DROPPING SE TO N CENTRAL AND FAR NE IL BY 31.00Z.
TRS
//DISCUSSION...UPDATED 00Z...
SURFACE ANTICYCLONE CENTERED OVER THE LOWER GREAT LAKES MOVES S
TO VA BY MORNING WHILE LOW PRESSURE MOVES FROM FAR SW ONTARIO TO
EASTERN LAKE SUPERIOR BY 30.12Z RESULTING IN LOCAL WINDS
GRADUALLY VEER FROM E TO SE TO SW DURING THE NIGHT. BELIEVE THAT
THE BOUNDARY LAYER HAS DRIED ENOUGH ACROSS NE IL TO RULE OUT ANY
SIGNIFICANT BR OR FG DEVELOPMENT THOUGH MAY SEE SOME HIGH END
MVFR VISIBILITY WITH SKC AND SURFACE WINDS AOB 5KT.
MODELS INDICATING A PERIOD OF CEILINGS IN THE 040-060 AGL RANGE
FROM PRE-DAWN THROUGH MID MORNING FRI AS LOW LEVEL WARM AIR
ADVECTION STRENGTHENS AS OVERNIGHT.
SW FLOW IN THE MIXED LAYER INCREASED PROGGED TO INCREASE TO
15-20KT AS THE COLD FRONT APPROACHES FROM THE NW SO EXPECT SOME
MODERATELY GUSTY SW WINDS MID-MORNING THROUGH THE AFTERNOON.
WITH WINDS CONTINUING TO VEER TO WSW AS THE COLD FRONT NEARS THE
SURFACE CONVERGENCE WEAKENS AS THE FLOW BECOMES RATHER PARALLEL
TO TH BOUNDARY. HOWEVER...FORECAST TEMPERATURE AND DEW POINT
PROFILES AND VARIOUS MODEL STABILITY PARAMETERS SUPPORT THE
OCCURRENCE OF SCATTERED CONVECTION ALONG AND A BIT AHEAD OF THE
ADVANCING FRONT SO HAVE INCLUDED PROB30 GROUPS FOR TSRA IN THE
CHI TERMINALS DURING THE LATER AFTERNOON THROUGH MID EVENING.
ONCE THE COLD FRONT PUSHES FURTHER S FRI EVENING AND HIGH
PRESSURE BUILDS OVER THE UPPER MIDWEST WITH WINDS PROGGED TO VEER
FURTHER TO OUT OF THE NNE...WITH MODEL GRAPHICAL AND NUMERIC
GUIDANCE SUGGESTING A STRATUS DECK TO SPREAD FROM THE S END OF
LAKE MI INLAND TO ORD AND MDW MID EVENING OR SO.
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE ALL ELEMENTS THROUGH MID FRI AFTERNOON.
* MEDIUM CONFIDENCE IN FORECAST ELEMENTS FOR LATE FRI AFTERNOON
AND EVENING.
TRS
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY...VFR. WX NIL.
SUNDAY...VFR. CHANCE TSRA AFTERNOON AND NIGHT WHICH COULD PRODUCE
BRIEF LOCAL MVFR/IFR.
MONDAY THROUGH WEDNESDAY. VFR. NO SIG WX.
TRS
&&
.MARINE...
303 PM CDT
HIGH PRESSURE OVER MICHIGAN WILL CONTINUE TO MOVE SOUTHEASTWARD
TONIGHT WHILE LOW PRESSURE MOVES FROM MINNESOTA TO LAKE SUPERIOR.
THE PRESSURE GRADIENT WILL BUILD ACROSS NORTHERN SECTIONS OF THE
LAKE OVERNIGHT AND SPREAD DOWN THE LAKE FRIDAY MORNING. THIS WILL
SUPPORT AND INCREASE IN SOUTHWESTERLY WINDS ACROSS THE LAKE THROUGH
FRIDAY MORNING. ANOTHER CONCERN LINGERING FOG OF SOUTHERN LAKE
MICHIGAN THIS AFTERNOON. HAVE ISSUED A DENSE FOG ADVISORY FOR MOST
OF THE IL/IN NEARSHORE WATERS AND THE FAR SOUTHWEST CORNER OF THE
OPEN WATERS. WITH WINDS REMAINING LIGHT ACROSS THE FAR SOUTH INTO
TONIGHT SO THIS FOG MAY CONTINUE THOUGH IT MAY LIFT TO LOW STRATUS
AROUND THE EDGES INTO EARLY EVENING. LOW CONFIDENCE IN HOW IT
EVOLVES BUT THE PRESSURE GRADIENT ORGANIZES SOMEWHAT THIS EVENING
SO A STEADIER...BUT STILL LIGHT...SOUTH WIND SHOULD RESULT AND MAY
HELP ANY REMAINING VSBY REDUCTIONS TO IMPROVE. A COLD FRONT WILL
DROP SOUTHWARD DOWN THE LAKE FRIDAY AND FRIDAY EVENING TURNING
WINDS NORTHERLY. WEAK HIGH PRESSURE WILL THEN BUILD IN SATURDAY
BRINGING WEAKENING WINDS INTO SATURDAY EVENING. STRONG LOW
PRESSURE WILL THEN MOVE FROM NORTHERN MINNESOTA/WESTERN ONTARIO
ACROSS LAKE SUPERIOR SUNDAY SENDING A COLD FRONT EASTWARD ACROSS
THE LAKE SUNDAY AFTERNOON OR EVENING. STRONG HIGH PRESSURE WILL
MOVE EAST ACROSS THE PLAINS AND MID AND UPPER MISSISSIPPI RIVER
VALLEY MONDAY. THERE WILL BE A STRONG PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS WITH A PUSH OF COOLER AIR SPREADING IN BEHIND THE
FRONT SO WINDS WILL BE INCREASING AS THEY TURN NORTHWEST THEN MORE
NORTHERLY. THE HIGH WILL THEN MOVE ACROSS THE LAKE
TUESDAY/WEDNESDAY BRINGING LIGHT AND VARIABLE WINDS.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
943 PM CDT THU AUG 29 2013
.DISCUSSION...
942 PM CDT
THE MAIN CHANGE TO THE GOING FORECAST WAS TO STRESS THE FOG A BIT
MORE OVERNIGHT INTO EARLY FRIDAY MORNING...ESPECIALLY FOR THE
SOUTHEAST HALF OF THE FORECAST AREA...AND ONCE AGAIN ALONG THE
LAKE MI SHORE NAMELY FOR OVERNIGHT.
THE BROAD AREA OF HIGH PRESSURE CENTERED TO OUR EAST CONTINUES TO
EVOLVE ITS WAY SOUTHEAST TOWARD THE MID-ATLANTIC. EARLIER FOG OVER
THE LAKEFRONT INCLUDING IN DOWNTOWN HAD BASICALLY DISSIPATED BY
7-7:30 PM. HOWEVER LATEST GOES FOG PRODUCT IS INDICATING A
RE-BLOSSOMING START OF FOG AND/OR STRATUS EAST OF CHICAGO ABOUT 25
MILES EAST OF CHICAGO. THE BOUNDARY LAYER HAS BEEN ABLE TO
DECOUPLE PER AMDAR SOUNDINGS AND SURFACE WIND OBS. LINGERING HIGH
DEW POINTS NEAR 70 AND LOW-LEVEL MIXING RATIOS AROUND 15 G/KG ARE
DRAPED ACROSS THE SOUTHERN AND WESTERN FORECAST AREA AND CLEAR
SKIES HAVE ALLOWED TEMPERATURES TO GET WITHIN A FEW DEGREES OF
THIS ALREADY AT A HANDFUL OF LOCATIONS.
WHILE THE PRESSURE GRADIENT WILL GRADUALLY BUILD IN FROM THE WEST
TONIGHT...MUCH OF THE EASTERN CWA SHOULD REMAIN DECOUPLED ENOUGH
FOR SURFACE WINDS TO REMAIN CALM. MODIFIED 00Z ILX SOUNDING AND
MODIFIED FORECAST SOUNDINGS FROM THE RAP AND NAM FOR CURRENT
CONDITIONS AT IKK/VPZ INDICATE PROFILES FAVORABLE FOR FOG BY
MIDNIGHT. HAVE BUMPED UP COVERAGE TO AREAS BUT THINK ANY DENSE FOG
WILL REMAIN PATCHY. AS FOR OVER THE LAKE...THE EXPANDING AREA EAST
OF CHICAGO WILL LIKELY ADVECT TOWARD THE IL SHORE AND POSSIBLY
EXPAND BACK TOWARD IN BEFORE THE RETURN FLOW SETTLES IN OVER THE
LAKE AFTER MIDNIGHT. GIVEN WHAT WAS SEEN EARLIER THURSDAY...SOME
OF THIS FOG COULD BE DENSE AS IT ROLLS INTO THE IL SHORE OVERNIGHT.
HAVE MADE ONLY SLIGHT TWEAKS TO MIN TEMPERATURES...WHICH PRIMARILY
LOOK ON TRACK.
EARLY LOOK AT 00Z NAM CONTINUES TO SHOW THE LIKELIHOOD OF
SCATTERED CONVECTION ON FRI AFTERNOON THROUGH ESPECIALLY MID-
EVE...WITH GREATEST CHANCES IN NORTHEAST IL/NORTHWEST
IN...INCLUDING ALL OF CHICAGOLAND. HIGH CAPE/MODEST SHEAR
ENVIRONMENT...ALONG WITH A SLIGHTLY MORE FAVORABLE VORT PATH THAN
PREV RUN...WOULD ALL STILL SUPPORT AN ISOLATED SEVERE THREAT.
MTF
&&
.PREV DISCUSSION...
309 PM CDT
THE MAIN FORECAST CONCERNS WILL BE THE CHANCES AND TIMING OF
THUNDERSTORM ACTIVITY LATE FRIDAY AND FRIDAY NIGHT. TEMPERATURES ARE
ALSO A SIGNIFICANT FOCUS AS IT APPEARS WE WILL BE ON A SEE SAW OVER
THE NEXT SEVERAL DAYS AS SEVERAL COLD FRONTS TAKE AIM ON THE AREA.
THE LAST BIT OF LOW CLOUDS FROM THIS MORNING ARE FINALLY
DISSIPATING JUST WEST OF KPNT EARLY THIS AFTERNOON...SETTING UP
MOSTLY SUNNY SKIES ACROSS THE REGION. HOWEVER...LOW CLOUDS AND FOG
CONTINUE TO FESTER ACROSS THE SOUTHEASTERN TIP OF LAKE
MICHIGAN...JUST OFF THE COOK COUNTY ILLINOIS AND LAKE AND PORTER
COUNTY INDIANA SHORES. ALTHOUGH THIS ACTIVITY HAS REMAINED MAINLY
OVER THE WATERS OF LAKE MICHIGAN THROUGH THE DAY...IT IS POSSIBLY
THAT SOME OF THIS FOG COULD ROLL IN ACROSS THE SHORES EARLY THIS
EVENING. THEREFORE...I ADDED THE MENTION OF AREAS OF FOG FOR THE
IMMEDIATE SHORE LINE. IF THIS FOG DOES MOVE ONSHORE...IT WILL LIKELY
BE DENSE...SO CONDITIONS WILL NEED TO BE MONITORED THIS EVENING. THE
GOOD NEWS IS THAT THE WINDS SHOULD SWITCH OUT OF THE SOUTH OVERNIGHT
TONIGHT...WHICH SHOULD ALLOW ANY FOG TO MOVE BACK OUT OVER THE LAKE
LATER TONIGHT.
THE MAIN WEATHER DISTURBANCE OF INTEREST LATER FRIDAY/FRIDAY
NIGHT...IS CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING ACROSS
NORTH DAKOTA...ALONG THE NORTHERN PERIPHERY OF THE UPPER RIDGE
ENCOMPASSING THE PLAINS. THIS FEATURE IS EXPECTED TO PRODUCE
CONVECTION WELL NORTH OF THE AREA TONIGHT. HOWEVER...A SURFACE COLD
FRONT IS FORECAST TO DROP SOUTHWARD ACROSS WISCONSIN THROUGH THE DAY
ON FRIDAY. TO THE SOUTH OF THIS FRONT...A THERMAL RIDGE WILL SHIFT
EASTWARD ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA....SETTING UP ANOTHER DAY OF HOT AND HUMID CONDITIONS. THIS
SHOULD ALLOW TEMPERATURES TO AGAIN TOP OUT IN THE LOWER TO MIDDLE
90S ACROSS THE AREA ON FRIDAY...WITH HEAT INDICES NEAR 100 DEGREES.
DURING THE LATE AFTERNOON AND EVENING HOURS...THIS COLD FRONT WILL
BEGIN TO MOVE OVER NORTHERN ILLINOIS. IT APPEARS THAT SCATTERED
CONVECTIVE INITIATION WILL OCCUR ACROSS SOUTHERN WISCONSIN BY MID
AFTERNOON...THEN PROGRESS SOUTHEASTWARD ACROSS NORTHERN ILLINOIS
LATER IN THE AFTERNOON AND INTO THE EVENING. IT APPEARS THERE WILL
BE A THREAT FOR SOME STRONG TO SEVERE STORMS WITH THIS ACTIVITY.
HOWEVER...DEEP LAYER SHEAR LOOKS TO REMAIN RATHER MARGINAL (20 TO 30
KT) FOR ORGANIZED CONVECTION. IN SPITE OF THIS...MODEL SOUNDINGS
INDICATE STEEP MID LEVEL LAPS RATES AND PROFILES SUPPORTIVE OF SOME
STRONG WIND GUSTS/MICRO-BURST...SO THE THREAT OF SEVERE STORMS IS NOT
ZERO. IN ADDITION...THE HIGH THETA-E AIR MASS AHEAD OF THE
APPROACHING FRONT...WITH PWATS EXPECTED TO BE AROUND 1.9
INCHES...COULD SUPPORT SOME TORRENTIAL DOWNPOURS IN THE STRONGEST
STORMS. THESE STORMS SHOULD DROP SOUTH AND EASTWARD ACROSS THE AREA
THROUGH THE EVENING. SOME THIS ACTIVITY COULD LINGER OVERNIGHT INTO
EARLY SATURDAY ACROSS MY FAR SOUTHERN COUNTIES.
SOME COOLER AIR ARRIVES ACROSS THE AREA FOR SATURDAY IN THE WAKE OF
THIS FRONTAL ZONE. THIS SHOULD DROP TEMPERATURES BACK INTO THE MID
TO UPPER 80S FOR SATURDAY.
A SECOND SYSTEM LOOKS TO TOP THE RIDGE AXIS ACROSS THE PLAINS...AND
THEN DIG SOUTHEASTWARD OVER THE GREAT LAKES LATE SUNDAY AND INTO
MONDAY. THIS SYSTEM LOOKS TO DRIVE ANOTHER...STRONGER COLD FRONT
ACROSS THE AREA DURING THE DAY ON SUNDAY. THIS APPEARS TO BE ANOTHER
DECENT SHOT FOR SOME SHOWERS AND THUNDERSTORMS INTO SUNDAY EVENING.
ONCE THIS FRONT PASSES BY...MUCH COOLER AND DRIER AIR WILL MOVE
ACROSS THE AREA FOR MONDAY AS A SURFACE HIGH BUILDS EASTWARD ACROSS
THE MID MISSISSIPPI RIVER VALLEY. THIS SHOULD RESULT IN HIGHS BACK
INTO THE 70S FOR MONDAY AND TUESDAY.
TEMPERATURES LOOK TO MODERATE BACK INTO THE 80S BY WEDNESDAY AS THE
THERMAL RIDGE SHIFTS EASTWARD ALONG THE BACK SIDE OF THE SURFACE
HIGH. HOWEVER...THE OVERALL PATTERN LOOKS TO REMAIN DRY ACROSS THE
REGION THROUGH THE MIDDLE OF NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* POSSIBLE MVFR VIS IN BR HZ LATER TONIGHT THRU EARLY FRI
MORNING.
* CHANCE OF SHRA/TSRA LATER FRI AFTERNOON TIL MID FRI EVENING.
* COLD FRONT DROPPING SE TO ACROSS N CENTRAL AND FAR NE IL BY
31.00Z.
TRS
//DISCUSSION...UPDATED 00Z...
SURFACE ANTICYCLONE CENTERED OVER THE LOWER GREAT LAKES MOVES S
TO VA BY MORNING WHILE LOW PRESSURE MOVES FROM FAR SW ONTARIO TO
EASTERN LAKE SUPERIOR BY 30.12Z RESULTING IN LOCAL WINDS
GRADUALLY VEER FROM E TO SE TO SW DURING THE NIGHT. BELIEVE THAT
THE BOUNDARY LAYER HAS DRIED ENOUGH ACROSS NE IL TO RULE OUT ANY
SIGNIFICANT BR OR FG DEVELOPMENT THOUGH MAY SEE SOME HIGH END
MVFR VISIBILITY WITH SKC AND SURFACE WINDS AOB 5KT.
MODELS INDICATING A PERIOD OF CEILINGS IN THE 040-060 AGL RANGE
FROM PRE-DAWN THROUGH MID MORNING FRI AS LOW LEVEL WARM AIR
ADVECTION STRENGTHENS AS OVERNIGHT.
SW FLOW IN THE MIXED LAYER INCREASED PROGGED TO INCREASE TO
15-20KT AS THE COLD FRONT APPROACHES FROM THE NW SO EXPECT SOME
MODERATELY GUSTY SW WINDS MID-MORNING THROUGH THE AFTERNOON.
WITH WINDS CONTINUING TO VEER TO WSW AS THE COLD FRONT NEARS THE
SURFACE CONVERGENCE WEAKENS AS THE FLOW BECOMES RATHER PARALLEL
TO TH BOUNDARY. HOWEVER...FORECAST TEMPERATURE AND DEW POINT
PROFILES AND VARIOUS MODEL STABILITY PARAMETERS SUPPORT THE
OCCURRENCE OF SCATTERED CONVECTION ALONG AND A BIT AHEAD OF THE
ADVANCING FRONT SO HAVE INCLUDED PROB30 GROUPS FOR TSRA IN THE
CHI TERMINALS DURING THE LATER AFTERNOON THROUGH MID EVENING.
ONCE THE COLD FRONT PUSHES FURTHER S FRI EVENING AND HIGH
PRESSURE BUILDS OVER THE UPPER MIDWEST WITH WINDS PROGGED TO VEER
FURTHER TO OUT OF THE NNE...WITH MODEL GRAPHICAL AND NUMERIC
GUIDANCE SUGGESTING A STRATUS DECK TO SPREAD FROM THE S END OF
LAKE MI INLAND TO ORD AND MDW MID EVENING OR SO.
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* HIGH CONFIDENCE ALL ELEMENTS THROUGH MID FRI AFTERNOON.
* MEDIUM CONFIDENCE IN FORECAST LATER FRI AFTERNOON AND FRI
EVENING.
TRS
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY...VFR. WX NIL.
SUNDAY...VFR. CHANCE TSRA AFTERNOON AND NIGHT WHICH COULD PRODUCE
BRIEF LOCAL MVFR/IFR.
MONDAY THROUGH WEDNESDAY. VFR. NO SIG WX.
TRS
&&
.MARINE...
303 PM CDT
HIGH PRESSURE OVER MICHIGAN WILL CONTINUE TO MOVE SOUTHEASTWARD
TONIGHT WHILE LOW PRESSURE MOVES FROM MINNESOTA TO LAKE SUPERIOR.
THE PRESSURE GRADIENT WILL BUILD ACROSS NORTHERN SECTIONS OF THE
LAKE OVERNIGHT AND SPREAD DOWN THE LAKE FRIDAY MORNING. THIS WILL
SUPPORT AND INCREASE IN SOUTHWESTERLY WINDS ACROSS THE LAKE THROUGH
FRIDAY MORNING. ANOTHER CONCERN LINGERING FOG OF SOUTHERN LAKE
MICHIGAN THIS AFTERNOON. HAVE ISSUED A DENSE FOG ADVISORY FOR MOST
OF THE IL/IN NEARSHORE WATERS AND THE FAR SOUTHWEST CORNER OF THE
OPEN WATERS. WITH WINDS REMAINING LIGHT ACROSS THE FAR SOUTH INTO
TONIGHT SO THIS FOG MAY CONTINUE THOUGH IT MAY LIFT TO LOW STRATUS
AROUND THE EDGES INTO EARLY EVENING. LOW CONFIDENCE IN HOW IT
EVOLVES BUT THE PRESSURE GRADIENT ORGANIZES SOMEWHAT THIS EVENING
SO A STEADIER...BUT STILL LIGHT...SOUTH WIND SHOULD RESULT AND MAY
HELP ANY REMAINING VSBY REDUCTIONS TO IMPROVE. A COLD FRONT WILL
DROP SOUTHWARD DOWN THE LAKE FRIDAY AND FRIDAY EVENING TURNING
WINDS NORTHERLY. WEAK HIGH PRESSURE WILL THEN BUILD IN SATURDAY
BRINGING WEAKENING WINDS INTO SATURDAY EVENING. STRONG LOW
PRESSURE WILL THEN MOVE FROM NORTHERN MINNESOTA/WESTERN ONTARIO
ACROSS LAKE SUPERIOR SUNDAY SENDING A COLD FRONT EASTWARD ACROSS
THE LAKE SUNDAY AFTERNOON OR EVENING. STRONG HIGH PRESSURE WILL
MOVE EAST ACROSS THE PLAINS AND MID AND UPPER MISSISSIPPI RIVER
VALLEY MONDAY. THERE WILL BE A STRONG PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS WITH A PUSH OF COOLER AIR SPREADING IN BEHIND THE
FRONT SO WINDS WILL BE INCREASING AS THEY TURN NORTHWEST THEN MORE
NORTHERLY. THE HIGH WILL THEN MOVE ACROSS THE LAKE
TUESDAY/WEDNESDAY BRINGING LIGHT AND VARIABLE WINDS.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
734 PM CDT THU AUG 29 2013
.DISCUSSION...
309 PM CDT
THE MAIN FORECAST CONCERNS WILL BE THE CHANCES AND TIMING OF
THUNDERSTORM ACTIVITY LATE FRIDAY AND FRIDAY NIGHT. TEMPERATURES ARE
ALSO A SIGNIFICANT FOCUS AS IT APPEARS WE WILL BE ON A SEE SAW OVER
THE NEXT SEVERAL DAYS AS SEVERAL COLD FRONTS TAKE AIM ON THE AREA.
THE LAST BIT OF LOW CLOUDS FROM THIS MORNING ARE FINALLY
DISSIPATING JUST WEST OF KPNT EARLY THIS AFTERNOON...SETTING UP
MOSTLY SUNNY SKIES ACROSS THE REGION. HOWEVER...LOW CLOUDS AND FOG
CONTINUE TO FESTER ACROSS THE SOUTHEASTERN TIP OF LAKE
MICHIGAN...JUST OFF THE COOK COUNTY ILLINOIS AND LAKE AND PORTER
COUNTY INDIANA SHORES. ALTHOUGH THIS ACTIVITY HAS REMAINED MAINLY
OVER THE WATERS OF LAKE MICHIGAN THROUGH THE DAY...IT IS POSSIBLY
THAT SOME OF THIS FOG COULD ROLL IN ACROSS THE SHORES EARLY THIS
EVENING. THEREFORE...I ADDED THE MENTION OF AREAS OF FOG FOR THE
IMMEDIATE SHORE LINE. IF THIS FOG DOES MOVE ONSHORE...IT WILL LIKELY
BE DENSE...SO CONDITIONS WILL NEED TO BE MONITORED THIS EVENING. THE
GOOD NEWS IS THAT THE WINDS SHOULD SWITCH OUT OF THE SOUTH OVERNIGHT
TONIGHT...WHICH SHOULD ALLOW ANY FOG TO MOVE BACK OUT OVER THE LAKE
LATER TONIGHT.
THE MAIN WEATHER DISTURBANCE OF INTEREST LATER FRIDAY/FRIDAY
NIGHT...IS CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING ACROSS
NORTH DAKOTA...ALONG THE NORTHERN PERIPHERY OF THE UPPER RIDGE
ENCOMPASSING THE PLAINS. THIS FEATURE IS EXPECTED TO PRODUCE
CONVECTION WELL NORTH OF THE AREA TONIGHT. HOWEVER...A SURFACE COLD
FRONT IS FORECAST TO DROP SOUTHWARD ACROSS WISCONSIN THROUGH THE DAY
ON FRIDAY. TO THE SOUTH OF THIS FRONT...A THERMAL RIDGE WILL SHIFT
EASTWARD ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA....SETTING UP ANOTHER DAY OF HOT AND HUMID CONDITIONS. THIS
SHOULD ALLOW TEMPERATURES TO AGAIN TOP OUT IN THE LOWER TO MIDDLE
90S ACROSS THE AREA ON FRIDAY...WITH HEAT INDICES NEAR 100 DEGREES.
DURING THE LATE AFTERNOON AND EVENING HOURS...THIS COLD FRONT WILL
BEGIN TO MOVE OVER NORTHERN ILLINOIS. IT APPEARS THAT SCATTERED
CONVECTIVE INITIATION WILL OCCUR ACROSS SOUTHERN WISCONSIN BY MID
AFTERNOON...THEN PROGRESS SOUTHEASTWARD ACROSS NORTHERN ILLINOIS
LATER IN THE AFTERNOON AND INTO THE EVENING. IT APPEARS THERE WILL
BE A THREAT FOR SOME STRONG TO SEVERE STORMS WITH THIS ACTIVITY.
HOWEVER...DEEP LAYER SHEAR LOOKS TO REMAIN RATHER MARGINAL (20 TO 30
KT) FOR ORGANIZED CONVECTION. IN SPITE OF THIS...MODEL SOUNDINGS
INDICATE STEEP MID LEVEL LAPS RATES AND PROFILES SUPPORTIVE OF SOME
STRONG WIND GUSTS/MICRO-BURST...SO THE THREAT OF SEVERE STORMS IS NOT
ZERO. IN ADDITION...THE HIGH THETA-E AIR MASS AHEAD OF THE
APPROACHING FRONT...WITH PWATS EXPECTED TO BE AROUND 1.9
INCHES...COULD SUPPORT SOME TORRENTIAL DOWNPOURS IN THE STRONGEST
STORMS. THESE STORMS SHOULD DROP SOUTH AND EASTWARD ACROSS THE AREA
THROUGH THE EVENING. SOME THIS ACTIVITY COULD LINGER OVERNIGHT INTO
EARLY SATURDAY ACROSS MY FAR SOUTHERN COUNTIES.
SOME COOLER AIR ARRIVES ACROSS THE AREA FOR SATURDAY IN THE WAKE OF
THIS FRONTAL ZONE. THIS SHOULD DROP TEMPERATURES BACK INTO THE MID
TO UPPER 80S FOR SATURDAY.
A SECOND SYSTEM LOOKS TO TOP THE RIDGE AXIS ACROSS THE PLAINS...AND
THEN DIG SOUTHEASTWARD OVER THE GREAT LAKES LATE SUNDAY AND INTO
MONDAY. THIS SYSTEM LOOKS TO DRIVE ANOTHER...STRONGER COLD FRONT
ACROSS THE AREA DURING THE DAY ON SUNDAY. THIS APPEARS TO BE ANOTHER
DECENT SHOT FOR SOME SHOWERS AND THUNDERSTORMS INTO SUNDAY EVENING.
ONCE THIS FRONT PASSES BY...MUCH COOLER AND DRIER AIR WILL MOVE
ACROSS THE AREA FOR MONDAY AS A SURFACE HIGH BUILDS EASTWARD ACROSS
THE MID MISSISSIPPI RIVER VALLEY. THIS SHOULD RESULT IN HIGHS BACK
INTO THE 70S FOR MONDAY AND TUESDAY.
TEMPERATURES LOOK TO MODERATE BACK INTO THE 80S BY WEDNESDAY AS THE
THERMAL RIDGE SHIFTS EASTWARD ALONG THE BACK SIDE OF THE SURFACE
HIGH. HOWEVER...THE OVERALL PATTERN LOOKS TO REMAIN DRY ACROSS THE
REGION THROUGH THE MIDDLE OF NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* POSSIBLE MVFR VIS IN BR HZ LATER TONIGHT THRU EARLY FRI
MORNING.
* CHANCE OF SHRA/TSRA LATER FRI AFTERNOON TIL MID FRI EVENING.
* COLD FRONT DROPPING SE TO ACROSS N CENTRAL AND FAR NE IL BY
31.00Z.
TRS
//DISCUSSION...UPDATED 00Z...
SURFACE ANTICYCLONE CENTERED OVER THE LOWER GREAT LAKES MOVES S
TO VA BY MORNING WHILE LOW PRESSURE MOVES FROM FAR SW ONTARIO TO
EASTERN LAKE SUPERIOR BY 30.12Z RESULTING IN LOCAL WINDS
GRADUALLY VEER FROM E TO SE TO SW DURING THE NIGHT. BELIEVE THAT
THE BOUNDARY LAYER HAS DRIED ENOUGH ACROSS NE IL TO RULE OUT ANY
SIGNIFICANT BR OR FG DEVELOPMENT THOUGH MAY SEE SOME HIGH END
MVFR VISIBILITY WITH SKC AND SURFACE WINDS AOB 5KT.
MODELS INDICATING A PERIOD OF CEILINGS IN THE 040-060 AGL RANGE
FROM PRE-DAWN THROUGH MID MORNING FRI AS LOW LEVEL WARM AIR
ADVECTION STRENGTHENS AS OVERNIGHT.
SW FLOW IN THE MIXED LAYER INCREASED PROGGED TO INCREASE TO
15-20KT AS THE COLD FRONT APPROACHES FROM THE NW SO EXPECT SOME
MODERATELY GUSTY SW WINDS MID-MORNING THROUGH THE AFTERNOON.
WITH WINDS CONTINUING TO VEER TO WSW AS THE COLD FRONT NEARS THE
SURFACE CONVERGENCE WEAKENS AS THE FLOW BECOMES RATHER PARALLEL
TO TH BOUNDARY. HOWEVER...FORECAST TEMPERATURE AND DEW POINT
PROFILES AND VARIOUS MODEL STABILITY PARAMETERS SUPPORT THE
OCCURRENCE OF SCATTERED CONVECTION ALONG AND A BIT AHEAD OF THE
ADVANCING FRONT SO HAVE INCLUDED PROB30 GROUPS FOR TSRA IN THE
CHI TERMINALS DURING THE LATER AFTERNOON THROUGH MID EVENING.
ONCE THE COLD FRONT PUSHES FURTHER S FRI EVENING AND HIGH
PRESSURE BUILDS OVER THE UPPER MIDWEST WITH WINDS PROGGED TO VEER
FURTHER TO OUT OF THE NNE...WITH MODEL GRAPHICAL AND NUMERIC
GUIDANCE SUGGESTING A STRATUS DECK TO SPREAD FROM THE S END OF
LAKE MI INLAND TO ORD AND MDW MID EVENING OR SO.
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* HIGH CONFIDENCE ALL ELEMENTS THROUGH MID FRI AFTERNOON.
* MEDIUM CONFIDENCE IN FORECAST LATER FRI AFTERNOON AND FRI
EVENING.
TRS
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY...VFR. WX NIL.
SUNDAY...VFR. CHANCE TSRA AFTERNOON AND NIGHT WHICH COULD PRODUCE
BRIEF LOCAL MVFR/IFR.
MONDAY THROUGH WEDNESDAY. VFR. NO SIG WX.
TRS
&&
.MARINE...
303 PM CDT
HIGH PRESSURE OVER MICHIGAN WILL CONTINUE TO MOVE SOUTHEASTWARD
TONIGHT WHILE LOW PRESSURE MOVES FROM MINNESOTA TO LAKE SUPERIOR.
THE PRESSURE GRADIENT WILL BUILD ACROSS NORTHERN SECTIONS OF THE
LAKE OVERNIGHT AND SPREAD DOWN THE LAKE FRIDAY MORNING. THIS WILL
SUPPORT AND INCREASE IN SOUTHWESTERLY WINDS ACROSS THE LAKE THROUGH
FRIDAY MORNING. ANOTHER CONCERN LINGERING FOG OF SOUTHERN LAKE
MICHIGAN THIS AFTERNOON. HAVE ISSUED A DENSE FOG ADVISORY FOR MOST
OF THE IL/IN NEARSHORE WATERS AND THE FAR SOUTHWEST CORNER OF THE
OPEN WATERS. WITH WINDS REMAINING LIGHT ACROSS THE FAR SOUTH INTO
TONIGHT SO THIS FOG MAY CONTINUE THOUGH IT MAY LIFT TO LOW STRATUS
AROUND THE EDGES INTO EARLY EVENING. LOW CONFIDENCE IN HOW IT
EVOLVES BUT THE PRESSURE GRADIENT ORGANIZES SOMEWHAT THIS EVENING
SO A STEADIER...BUT STILL LIGHT...SOUTH WIND SHOULD RESULT AND MAY
HELP ANY REMAINING VSBY REDUCTIONS TO IMPROVE. A COLD FRONT WILL
DROP SOUTHWARD DOWN THE LAKE FRIDAY AND FRIDAY EVENING TURNING
WINDS NORTHERLY. WEAK HIGH PRESSURE WILL THEN BUILD IN SATURDAY
BRINGING WEAKENING WINDS INTO SATURDAY EVENING. STRONG LOW
PRESSURE WILL THEN MOVE FROM NORTHERN MINNESOTA/WESTERN ONTARIO
ACROSS LAKE SUPERIOR SUNDAY SENDING A COLD FRONT EASTWARD ACROSS
THE LAKE SUNDAY AFTERNOON OR EVENING. STRONG HIGH PRESSURE WILL
MOVE EAST ACROSS THE PLAINS AND MID AND UPPER MISSISSIPPI RIVER
VALLEY MONDAY. THERE WILL BE A STRONG PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS WITH A PUSH OF COOLER AIR SPREADING IN BEHIND THE
FRONT SO WINDS WILL BE INCREASING AS THEY TURN NORTHWEST THEN MORE
NORTHERLY. THE HIGH WILL THEN MOVE ACROSS THE LAKE
TUESDAY/WEDNESDAY BRINGING LIGHT AND VARIABLE WINDS.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...DENSE FOG ADVISORY...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ779
UNTIL 10 PM THURSDAY.
&&
$$
Area Forecast Discussion
National Weather Service Lincoln IL
655 PM CDT Thu Aug 29 2013
.DISCUSSION...
ISSUED 300 PM CDT Thu Aug 29 2013
Low clouds and fog help to keep some areas high temps a little less
hot today...but it appears that some influences from air off of
Lake Michigan gave a boost to our stratus layer/fog based on
satellite trends last night. There is some concern that we could see
fog again tonight, but winds turning southeasterly by Fri morning
should help preclude any lake influence and a repeat of this
morning.
A lingering stationary front just southwest of our counties could
be a focus for a few late afternoon showers/storms, but the
lack of towering cu to this point near the front leads us to
believe we may not see as much convection as yesterday
afternoon/eve. Otherwise, the main concerns in the immediate
short term will be sky/fog/temps.
An approaching cold front for Friday night will add thunderstorm
chances to the mix, and those storm chances may linger into
Saturday morning for the southeast areas.
Additional attention will go to the cold front for Sunday night that
will bring some welcome relief to the heat and humidity. That
front may provide more than just scattered showers and storms, and
could possibly help with the developing drought conditions.
SHORT TERM...Tonight through Saturday night.
The low stratus and fog took its time clearing out in the
northeast half of our forecast area /fa/ today, holding temps in
the 80s into mid afternoon. That moisture mixed out some, but a
lingering cumulus field in its wake confirms that low level
moisture will remain in the area tonight. Once the nocturnal
inversion and subsidence develops, we will see the potential for
fog to reform later tonight. We added fog to the grids tonight
into tomorrow morning, but visibility is not expected to become a
major problem.
As previously mentioned, we are not expecting much of any
showers/storms in our counties late this afternoon and early eve.
A line of showers has popped up in far southeast IL and into
Kentucky, with the axis of instability extending NW toward
Litchfield and then west to Pittsfield/Quincy. If that position
holds true, we will be just northeast of any precip. We will watch
closely for development, but for now will stay the course with a
dry forecast into this evening.
Another hot day is forecast for Friday, with highs in the mid to
upper 90s in the west, with heat indices of 100 to 105F. The
eastern areas may see lower highs due to some morning cloud cover,
but they will clear in time to create uncomfortable heat indices
of 95 to 100F. A capping inversion should keep storms at bay
during the day on Friday, despite some short term models kicking
off storms before 00z/7pm. A cold front is expected to arrive
Friday night, triggering scattered showers and storms as it moves
from nw to se across the area. The frontal passage at night will
limit some of the potential convection as nocturnal stabilization
removes some instability. The lack of a low level jet will limit
night time storms along the front as well.
The timing of the front looks to be slow enough that areas
southeast of mattoon to paris could see storms linger into
Saturday, so we kept chance pops going in that area.
LONG TERM...Sunday through Thursday.
Sunday will be the last day of our extended hot spell as a more
prominent cold front arrives in our nw area. Increasing mid and
high clouds by afternoon may help to keep highs in the upper 80s
to lower 90s, but dewpoints around 70 will push heat index
readings into the mid-upper 90s. Storm chances will increase Sunday
afternoon in the nw as the front arrives. There may be some
potential for severe storms, but it is still too early to pinpoint
any locations of interest.
Precipitable water values climb to 1.75" by Sunday night, so any
storms may drop a quick 1-2" of rain. That could provide some much
needed rainfall, as portions of our western area have just been
included in the moderate drought category.
Much less humid air is forecast for Labor day through Wednesday.
Highs on Tuesday may not climb much into the 80s, with overnight
lows in the 50s early next week. Some warming is projected for
Wednesday as high climb back toward the middle 80s, but another
quick moving cold front Wed night will drop highs back down
around 80 for Thursday. There may be a stray shower or storm along
that front Wed night, but for now we will continue a dry forecast.
SHIMON
&&
.AVIATION...
ISSUED 650 PM CDT Thu Aug 29 2013
Main concern with aviation forecast for central IL airports is how
much fog and stratus will develop overnight into early Friday morning.
Frontal boundary just sw of central IL from eastern IA into sw IL and
central KY will be quasi-stationary tonight and then push ne
across central IL during Friday morning. Any isolated shower or
thunderstorms that form along the boundary until 03Z/10 pm will
stay sw of central IL airports. Moist airmass still in place
behind the front with dewpoints settling into the upper 60s and
lower 70s tonight. HRRR which did well with Stratus and fog last
night and this morning is not showing too much fog and stratus
over central IL overnight, perhaps due to less influence of Lake MI
moisture source as light ene winds turn more sse overnight, so not
a fetch off Lake MI like last night. Models still hint at best
development of fog/stratus over eastern IL from 08Z-14Z and will
continue to carry tempo groups from 09Z-13Z of 1-2 miles fog and
scattered to broken 200-600 ft ceilings especially at BMI, DEC &
CMI. Winds turn sw at 7-10 kts during Friday morning as warm front
pushes eastward through IL. A cold front pushing southward into
northern IL nearing I-80 by 7 pm Friday could bring isolated to
scattered showers & thunderstorms into central IL Friday evening,
just beyond this 24 hour TAF forecast.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
255 AM CDT WED AUG 28 2013
.DISCUSSION...
915 PM CDT
SOME SMALL CHANGES MADE TO THE GOING FORECAST THIS EVE. HAVE
CONFINED THE POPS IN IL MORE TO JUST FAR NORTHEAST IL MOVING THEM
EAST OF ROCKFORD. HAVE ALSO BUMPED UP CLOUD COVER WEDNESDAY
MORNING IN NORTHEAST IL AND NORTHWEST IN AND SLOWED THE MORNING
TEMPERATURE CLIMB...NAMELY NEAR THE LAKE MI SHORE INCLUDING
DOWNTOWN CHICAGO.
CONTINUE TO MONITOR CONVECTIVE BEHAVIOR OVER EASTERN AND CENTRAL
WISCONSIN AS WE MOVE THROUGH THE LATE EVE INTO THE OVERNIGHT.
STORMS HAVE BEEN FIRING SINCE MID-AFTERNOON ALONG THE ELONGATED
SURFACE BOUNDARY AND WITHIN THE PERIPHERY OF THE HEAT DOME/UPPER
RIDGE AND PWAT MAX /AROUND TWO AND A QUARTER ON 00Z GRB SOUNDING/.
THESE HAVE SLOWLY EVOLVED SOUTHEASTWARD FEEDING ON INSTABILITY AND
THE EDGE OF THE CAP AND MOVING WITHIN THE MEAN NW MID-LEVEL FLOW.
STORM MODE ACROSS EASTERN WI HAS BEEN MAINLY DISCRETE...INCLUDING
A COUPLE SEVERE SUPERCELLS. OUTFLOWS HAVE GENERALLY MERGED THOUGH
PER THE GRB RADAR AND OBSERVATIONS...AND THE MOST PRONOUNCED AND
FURTHEST SOUTH ONE IS APPROACHING AT AROUND 20 KT. WHILE THERE IS
AMPLE INSTABILITY PRESENT...IT APPEARS A LOW-LEVEL INVERSION IS
DEVELOPING BASED ON AMDAR SOUNDINGS AND THE EXPANDING MKX RADAR
BLOOM. SO POTENTIAL FOR NEW CONVECTION ALONG THIS OUTFLOW MAY BE
WANING...AS MAY BE THE FORWARD PROPAGATION SPEED UNLESS SOME NEW
CONVECTION DEVELOPS. STILL SOME POTENTIAL FOR THE ADJACENT LAKE MI
AREAS TO BE CLIPPED GIVEN RAP FORECAST CORFIDI VECTOR STORM
MOTIONS...AND ESPECIALLY IF STORMS AND ASSOCIATED OUTFLOWS PICK UP
PACE SOUTHWARD OVER THE LAKE. THERE WOULD BE SOME WIND POTENTIAL
WITH THESE...BUT OVERALL RADAR TRENDS IN THE PAST HALF HOUR
UPSTREAM POINT TOWARD ANY STRONG STORM POTENTIAL DROPPING QUICKLY.
GIVEN THE PHASED OUTFLOWS IT DOES LOOK LIKE THE SURFACE WIND
SHIFT TO N/NE MAY OCCUR EARLIER THAN ORIGINALLY THOUGHT IN
NORTHEAST IL...WHICH MEANS ADVECTION OF THE MARINE LAYER OVER
LAND TO OCCUR MORE DURING NIGHT. THE 00Z NAM IS MORE PESSIMISTIC
THAN ITS PREDECEASING RUN WITH A MOISTENING LOW-LEVEL INVERSION AND
CLOUDS...AND THAT AGREES WITH THE RAP. THIS MAKES SENSE NOT
NECESSARILY GIVEN CLIMATOLOGY FOR LATE AUG BUT CLIMATOLOGY GIVEN
THE SYNOPTIC SITUATION AND UPSTREAM OBS OF CIGS BEHIND THE FRONT.
WHILE THERE IS POTENTIAL FOR FOG TOO FROM THE MARINE
LAYER...FORECAST SOUNDINGS WOULD INDICATE MORE FAVORED STRATUS AND
THAT HAS BEEN THE OBSERVATIONAL TREND THUS FAR. SO HAVE SLOWED
THE MORNING TEMPERATURE CLIMB OVER CHICAGO AND FAR NW IN BUT NOT
ADJUSTED HIGHS AT THIS POINT.
MTF
//PREV DISCUSSION...
252 PM CDT
LATE SEASON HEAT HAS DEVELOPED THIS AFTERNOON ACROSS NORTHERN
IL/NORTHWEST IN WITH TEMPS PUSHING INTO THE MID 90S...WITH A FEW
AREAS TOUCHING THE UPR 90S. THIS COUPLED WITH DEW POINTS HOLDING
AROUND 70 DEGREES HAS RESULTED IN HEAT INDEX VALUES BETWEEN 98-105
IN SEVERAL LOCATIONS. THE HEAT ADVISORY HAS REMAINED IN PLACE
ACROSS LEE/OGLE/DEKALB/BOONE/WINNEBAGO COUNTIES.
THE MAIN CHALLENGE FOR THIS EVENING THROUGH THE OVERNIGHT WILL BE ON
POSSIBLE CONVECTION WITH A FEW STRONG STORMS DEVELOPING ALONG A
BOUNDARY...WHICH IS PROGGED TO BE SLIDING SOUTHEAST ACROSS WISCONSIN
INTO NORTHEAST IL/NORTHWEST IN. THE CHANNEL OF BETTER ATMOSPHERIC
MOISTURE WAS ORIENTED FROM THE HIGH PLAINS STRETCHING EAST THROUGH
THE UPPER MIDWEST THEN BENDING SOUTHEAST THROUGH THE GREAT LAKES
REGION THIS AFTERNOON. THIS APPEARS TO FIT WELL ALONG THE PROGGED
586-590 HEIGHT CONTOUR...WHICH APPEARS TO REMAIN NEARLY STATIONARY
THROUGH THE NEXT 24 HOURS. THIS AFTERNOON THE BOUNDARY WAS
POSITIONED ACROSS THE UPPER MIDWEST THROUGH THE UPPER PENINSULA OF
MICHIGAN...WHICH IS EXPECTED TO BE THE FOCAL POINT FOR CONVECTIVE
GENERATION LATER THIS AFTERNOON. CURRENT TIMING OF ARRIVAL INTO
NORTHERN IL CONTINUES TO BE JUST AFT 00Z...WITH THE PEAK BETWEEN
03-06Z. WITH THE VERY WARM SFC CONDITIONS THIS AFTN...POTENTIAL
ENERGY WILL LIKELY REMAIN ELEVATED UPON ARRIVAL OF
CLOUDS/CONVECTION...WHICH COULD FURTHER ENHANCE THUNDERSTORMS TO
POSSIBLY REACHING SEVERE LIMITS.
THE LOCATION OF GREATEST CONCERN WILL LIKELY BE ALONG AND NORTHEAST
OF A ROCKFORD TO KANKAKEE LINE...WITH THE MAIN HAZARDS FROM
THUNDERSTORMS BEING BRIEF HEAVY DOWNPOURS/WIND GUSTS TO 60MPH/HAIL
UP TO 1".
AS THE BOUNDARY SLIDES SOUTH ACROSS THE CWFA AFTER MIDNIGHT...WINDS
WILL TURN NORTH/NORTHEAST. LLVL MOISTURE APPEARS TO LINGER THRU
DAYBREAK WED. OVERNIGHT LOWS WILL REMAIN MILD ONE MORE NIGHT IN THE
LOW 70S...TO MID 70S CLOSER TO DOWNTOWN CHICAGO.
WEDNESDAY...
MID-LVL RIDGE CENTER WILL DRIFT SOUTHWEST...ALLOWING HEIGHTS TO
WEAKEN MARGINALLY OVER THE WESTERN GREAT LAKES REGION. GUIDANCE
CONTINUES TO PROG A WEAK WAVE SLIDING ACROSS THE NORTHERN CWFA WED
MORNING...WHICH ALONG WITH THE LINGERING LLVL MOISTURE COULD
TRANSLATE INTO POSSIBLE SHRA/TSRA WED MORNING FOR THE
CENTRAL/SOUTHERN CWFA. AT THIS TIME HAVE MAINTAINED A DRY FORECAST
FOR WED AS ANTI-CYCLONIC FLOW SHOULD SLOWLY SLIDE SOUTH ACROSS THE
LAKES AND STEADILY DRY THE SFC. NORTHEAST LLVL FLOW WILL CONTINUE TO
USHER IN DRIER AIR...WITH SLIGHTLY COOLER TEMPS ALONG THE LAKESHORE
COMMUNITIES. TEMPS FOR FAR NORTHEAST IL/NORTHWEST IN WILL HOVER IN
THE LOW/MID 80S...MEANWHILE FURTHER INLAND TEMPS WILL WARM INTO THE
UPR 80S TO POSSIBLY LOWER 90S ALONG AND SOUTH OF A LASALLE TO
KANKAKEE LINE.
CONFIDENCE...HIGH.
THURSDAY THROUGH LABOR DAY...
CONSIDERABLE CHANGES HAVE TAKEN PLACE IN THE FINAL PERIODS OF THE
EXTENDED...HOWEVER MODEL SPREAD DOES APPEAR TO HAVE DIMINISHED
MARGINALLY WITH RESPECT TO HIGH TEMPS FOR THE HOLIDAY WEEKEND.
ENSEMBLES CONTINUE TO DEMONSTRATE NOISE WITH A WIDE RANGE OF
SOLUTIONS BEYOND FRI. GUIDANCE DOES CONTINUE TO SHOW MID-LVL RIDGE
INFLUENCING THE WEATHER FOR THE WESTERN GREAT LAKES
THUR/FRI...HOWEVER WITH THE CWFA REMAINING ALONG THE NORTHEAST
PERIPHERY OF THE RIDGE...THE PROBABILITY OF ANY WAVES GENERATING
CLOUDS/CONVECTION IS INCREASED FOR THE AREA. CURRENT THINKING IS
THAT SFC RIDGE FROM WED WILL REMAIN IN PLACE THRU THUR THEN BEGIN TO
DRIFT SOUTHEAST THUR NIGHT. THIS WILL BRING THE NEXT CHC FOR
SHRA/TSRA TO THE CWFA THUR NIGHT INTO FRI...LINGERING THRU SAT
BEFORE BEGINNING TO DRY BACK OUT FOR SUN AND LABOR DAY.
ECMWF/GFS HAVE CONTINUED TO PROG A TROUGH DEVELOPING OVER THE
CANADIAN ROCKIES FRI AND PUSHING OVER THE GREAT LAKES REGION SUN.
WITH THE NOW EXPECTED TROUGHING EXPECTED ACROSS THE REGION FOR THE
SECOND HALF OF THE WEEKEND...TEMPS WILL LIKELY SWING IN THE COOLER
DIRECTION WITH HIGHS IN THE UPR 70S TO POSSIBLY MID 80S FOR LABOR
DAY.
CONFIDENCE...MEDIUM.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* WINDS BCMG NORTH EARLY THIS MORNING AND THEN NE SHORTLY THERE
AFTER.
* MVFR TO IFR CIGS ARE PSBL EARLY THIS MORNING.
* MVFR VSBY IS PSBL LATE TONIGHT INTO THURSDAY MORNING.
JEE
//DISCUSSION...UPDATED 06Z...
A BROAD AREA OF LOW PRESSURE STRETCHES FROM LAKE ONTARIO THROUGH
SOUTHERN WI WITH THE LOWS COLD FRONT FROM SAGINAW MI TO LA CROSSE
WI. THE FRONT WILL CONTINUE TO SINK SOUTH REACHING THE TERMINALS
EARLY THIS MORNING. WINDS WILL BECOME NORTH BEHIND THE FRONT AND
MVFR TO IFR CIGS MAY ACCOMPANY THE FRONTAL PASSAGE. LATEST
GUIDANCE SUGGESTS THE LOWER CIGS WILL NOT MAKE IT SOUTH OF THE
WI/IL STATE LINE AND TRENDS ON SATELLITE WOULD SUPPORT THIS TRAIN
OF THOUGHT. HOWEVER...DID NOT FEEL COMFORTABLE PULLING THE LOWER
CIGS JUST YET SO KEPT IN FEW TO SCT IFR/MVFR CIGS THIS MORNING.
ALSO THINKING VSBY WILL REMAIN VFR ABOVE 6SM THIS MORNING.
WINDS BECOME NE ARND 10 KT THIS MORNING WITH ANY LOWER CLOUD COVER
BURNING OFF BY MID AFTERNOON. ADDED IN THE POSSIBILITY OF MVFR
VSBY LATE TONIGHT AS GUIDANCE AND MODEL SOUNDINGS ARE ALL
SUGGESTING THE LOW LEVELS WILL BE RATHER SATURATED TONIGHT.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN WIND TRENDS...MEDIUM-HIGH CONFIDENCE IN TIMING.
* LOW CONFIDENCE IN MVFR/IFR CIGS. CIGS MAY REMAIN VFR THROUGH THE
PERIOD.
* MEDIUM CONFIDENCE IN REDUCED VSBY LATE TONIGHT.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...VFR.
FRIDAY...CHANCE TSRA...MAINLY FRIDAY EVENING.
SATURDAY...CHANCE TSRA.
SUNDAY...SLIGHT CHANCE TSRA.
MONDAY...VFR.
RC
&&
.MARINE...
254 AM CDT
A BROAD LOW IS OVER SOUTHERN LAKE MI AND THE LOWER MI PENINSULA AND
ITS COLD FRONT IS STRETCHED ACROSS SOUTHERN WI SINKING SOUTH. THE
FRONT WILL CLEAR THE SOUTHERN END OF THE LAKE EARLY THIS MORNING
WITH NORTH WINDS 10-20 KT EXPECTED BEHIND IT. LOW STRATUS AND FOG
HAVE ALSO BEEN REPORTED BEHIND THE FRONT...BUT EXPECTING BOTH OF
THOSE TO BURN OFF THIS MORNING. HIGH PRESSURE SETTLES IN BEHIND THE
FRONT WITH WINDS DIMINISHING AND BECOMING VARIABLE THURSDAY
AFTERNOON. THE HIGH SHIFTS EAST THURSDAY NIGHT AND WINDS BECOME
SOUTH. LOW PRESSURE CURRENTLY OVER THE CENTRAL PLAINS BEGINS TO
MOVE EAST FRIDAY WHILE A STRONGER LOW FORMS OVER SASKATCHEWAN
FRIDAY. THE PLAINS LOW MERGES WITH THE STRONGER LOW AS THE STRONGER
LOW MOVES NORTH OF THE GREAT LAKES SATURDAY NIGHT AND SUNDAY. LIGHT
WINDS TURN EAST AHEAD OF THE LOW FRIDAY NIGHT AND THEN SOUTH
SATURDAY NIGHT. THE LOWS COLD FRONT SWEEPS OVER THE LAKE SUNDAY
NIGHT WITH WINDS BECOMING NORTH BEHIND IT. GUSTS UP TO 30 KT ARE
VERY POSSIBLE BEHIND THE FRONT THROUGH MONDAY NIGHT.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1251 AM CDT WED AUG 28 2013
.DISCUSSION...
915 PM CDT
SOME SMALL CHANGES MADE TO THE GOING FORECAST THIS EVE. HAVE
CONFINED THE POPS IN IL MORE TO JUST FAR NORTHEAST IL MOVING THEM
EAST OF ROCKFORD. HAVE ALSO BUMPED UP CLOUD COVER WEDNESDAY
MORNING IN NORTHEAST IL AND NORTHWEST IN AND SLOWED THE MORNING
TEMPERATURE CLIMB...NAMELY NEAR THE LAKE MI SHORE INCLUDING
DOWNTOWN CHICAGO.
CONTINUE TO MONITOR CONVECTIVE BEHAVIOR OVER EASTERN AND CENTRAL
WISCONSIN AS WE MOVE THROUGH THE LATE EVE INTO THE OVERNIGHT.
STORMS HAVE BEEN FIRING SINCE MID-AFTERNOON ALONG THE ELONGATED
SURFACE BOUNDARY AND WITHIN THE PERIPHERY OF THE HEAT DOME/UPPER
RIDGE AND PWAT MAX /AROUND TWO AND A QUARTER ON 00Z GRB SOUNDING/.
THESE HAVE SLOWLY EVOLVED SOUTHEASTWARD FEEDING ON INSTABILITY AND
THE EDGE OF THE CAP AND MOVING WITHIN THE MEAN NW MID-LEVEL FLOW.
STORM MODE ACROSS EASTERN WI HAS BEEN MAINLY DISCRETE...INCLUDING
A COUPLE SEVERE SUPERCELLS. OUTFLOWS HAVE GENERALLY MERGED THOUGH
PER THE GRB RADAR AND OBSERVATIONS...AND THE MOST PRONOUNCED AND
FURTHEST SOUTH ONE IS APPROACHING AT AROUND 20 KT. WHILE THERE IS
AMPLE INSTABILITY PRESENT...IT APPEARS A LOW-LEVEL INVERSION IS
DEVELOPING BASED ON AMDAR SOUNDINGS AND THE EXPANDING MKX RADAR
BLOOM. SO POTENTIAL FOR NEW CONVECTION ALONG THIS OUTFLOW MAY BE
WANING...AS MAY BE THE FORWARD PROPAGATION SPEED UNLESS SOME NEW
CONVECTION DEVELOPS. STILL SOME POTENTIAL FOR THE ADJACENT LAKE MI
AREAS TO BE CLIPPED GIVEN RAP FORECAST CORFIDI VECTOR STORM
MOTIONS...AND ESPECIALLY IF STORMS AND ASSOCIATED OUTFLOWS PICK UP
PACE SOUTHWARD OVER THE LAKE. THERE WOULD BE SOME WIND POTENTIAL
WITH THESE...BUT OVERALL RADAR TRENDS IN THE PAST HALF HOUR
UPSTREAM POINT TOWARD ANY STRONG STORM POTENTIAL DROPPING QUICKLY.
GIVEN THE PHASED OUTFLOWS IT DOES LOOK LIKE THE SURFACE WIND
SHIFT TO N/NE MAY OCCUR EARLIER THAN ORIGINALLY THOUGHT IN
NORTHEAST IL...WHICH MEANS ADVECTION OF THE MARINE LAYER OVER
LAND TO OCCUR MORE DURING NIGHT. THE 00Z NAM IS MORE PESSIMISTIC
THAN ITS PREDECEASING RUN WITH A MOISTENING LOW-LEVEL INVERSION AND
CLOUDS...AND THAT AGREES WITH THE RAP. THIS MAKES SENSE NOT
NECESSARILY GIVEN CLIMATOLOGY FOR LATE AUG BUT CLIMATOLOGY GIVEN
THE SYNOPTIC SITUATION AND UPSTREAM OBS OF CIGS BEHIND THE FRONT.
WHILE THERE IS POTENTIAL FOR FOG TOO FROM THE MARINE
LAYER...FORECAST SOUNDINGS WOULD INDICATE MORE FAVORED STRATUS AND
THAT HAS BEEN THE OBSERVATIONAL TREND THUS FAR. SO HAVE SLOWED
THE MORNING TEMPERATURE CLIMB OVER CHICAGO AND FAR NW IN BUT NOT
ADJUSTED HIGHS AT THIS POINT.
MTF
//PREV DISCUSSION...
252 PM CDT
LATE SEASON HEAT HAS DEVELOPED THIS AFTERNOON ACROSS NORTHERN
IL/NORTHWEST IN WITH TEMPS PUSHING INTO THE MID 90S...WITH A FEW
AREAS TOUCHING THE UPR 90S. THIS COUPLED WITH DEW POINTS HOLDING
AROUND 70 DEGREES HAS RESULTED IN HEAT INDEX VALUES BETWEEN 98-105
IN SEVERAL LOCATIONS. THE HEAT ADVISORY HAS REMAINED IN PLACE
ACROSS LEE/OGLE/DEKALB/BOONE/WINNEBAGO COUNTIES.
THE MAIN CHALLENGE FOR THIS EVENING THROUGH THE OVERNIGHT WILL BE ON
POSSIBLE CONVECTION WITH A FEW STRONG STORMS DEVELOPING ALONG A
BOUNDARY...WHICH IS PROGGED TO BE SLIDING SOUTHEAST ACROSS WISCONSIN
INTO NORTHEAST IL/NORTHWEST IN. THE CHANNEL OF BETTER ATMOSPHERIC
MOISTURE WAS ORIENTED FROM THE HIGH PLAINS STRETCHING EAST THROUGH
THE UPPER MIDWEST THEN BENDING SOUTHEAST THROUGH THE GREAT LAKES
REGION THIS AFTERNOON. THIS APPEARS TO FIT WELL ALONG THE PROGGED
586-590 HEIGHT CONTOUR...WHICH APPEARS TO REMAIN NEARLY STATIONARY
THROUGH THE NEXT 24 HOURS. THIS AFTERNOON THE BOUNDARY WAS
POSITIONED ACROSS THE UPPER MIDWEST THROUGH THE UPPER PENINSULA OF
MICHIGAN...WHICH IS EXPECTED TO BE THE FOCAL POINT FOR CONVECTIVE
GENERATION LATER THIS AFTERNOON. CURRENT TIMING OF ARRIVAL INTO
NORTHERN IL CONTINUES TO BE JUST AFT 00Z...WITH THE PEAK BETWEEN
03-06Z. WITH THE VERY WARM SFC CONDITIONS THIS AFTN...POTENTIAL
ENERGY WILL LIKELY REMAIN ELEVATED UPON ARRIVAL OF
CLOUDS/CONVECTION...WHICH COULD FURTHER ENHANCE THUNDERSTORMS TO
POSSIBLY REACHING SEVERE LIMITS.
THE LOCATION OF GREATEST CONCERN WILL LIKELY BE ALONG AND NORTHEAST
OF A ROCKFORD TO KANKAKEE LINE...WITH THE MAIN HAZARDS FROM
THUNDERSTORMS BEING BRIEF HEAVY DOWNPOURS/WIND GUSTS TO 60MPH/HAIL
UP TO 1".
AS THE BOUNDARY SLIDES SOUTH ACROSS THE CWFA AFTER MIDNIGHT...WINDS
WILL TURN NORTH/NORTHEAST. LLVL MOISTURE APPEARS TO LINGER THRU
DAYBREAK WED. OVERNIGHT LOWS WILL REMAIN MILD ONE MORE NIGHT IN THE
LOW 70S...TO MID 70S CLOSER TO DOWNTOWN CHICAGO.
WEDNESDAY...
MID-LVL RIDGE CENTER WILL DRIFT SOUTHWEST...ALLOWING HEIGHTS TO
WEAKEN MARGINALLY OVER THE WESTERN GREAT LAKES REGION. GUIDANCE
CONTINUES TO PROG A WEAK WAVE SLIDING ACROSS THE NORTHERN CWFA WED
MORNING...WHICH ALONG WITH THE LINGERING LLVL MOISTURE COULD
TRANSLATE INTO POSSIBLE SHRA/TSRA WED MORNING FOR THE
CENTRAL/SOUTHERN CWFA. AT THIS TIME HAVE MAINTAINED A DRY FORECAST
FOR WED AS ANTI-CYCLONIC FLOW SHOULD SLOWLY SLIDE SOUTH ACROSS THE
LAKES AND STEADILY DRY THE SFC. NORTHEAST LLVL FLOW WILL CONTINUE TO
USHER IN DRIER AIR...WITH SLIGHTLY COOLER TEMPS ALONG THE LAKESHORE
COMMUNITIES. TEMPS FOR FAR NORTHEAST IL/NORTHWEST IN WILL HOVER IN
THE LOW/MID 80S...MEANWHILE FURTHER INLAND TEMPS WILL WARM INTO THE
UPR 80S TO POSSIBLY LOWER 90S ALONG AND SOUTH OF A LASALLE TO
KANKAKEE LINE.
CONFIDENCE...HIGH.
THURSDAY THROUGH LABOR DAY...
CONSIDERABLE CHANGES HAVE TAKEN PLACE IN THE FINAL PERIODS OF THE
EXTENDED...HOWEVER MODEL SPREAD DOES APPEAR TO HAVE DIMINISHED
MARGINALLY WITH RESPECT TO HIGH TEMPS FOR THE HOLIDAY WEEKEND.
ENSEMBLES CONTINUE TO DEMONSTRATE NOISE WITH A WIDE RANGE OF
SOLUTIONS BEYOND FRI. GUIDANCE DOES CONTINUE TO SHOW MID-LVL RIDGE
INFLUENCING THE WEATHER FOR THE WESTERN GREAT LAKES
THUR/FRI...HOWEVER WITH THE CWFA REMAINING ALONG THE NORTHEAST
PERIPHERY OF THE RIDGE...THE PROBABILITY OF ANY WAVES GENERATING
CLOUDS/CONVECTION IS INCREASED FOR THE AREA. CURRENT THINKING IS
THAT SFC RIDGE FROM WED WILL REMAIN IN PLACE THRU THUR THEN BEGIN TO
DRIFT SOUTHEAST THUR NIGHT. THIS WILL BRING THE NEXT CHC FOR
SHRA/TSRA TO THE CWFA THUR NIGHT INTO FRI...LINGERING THRU SAT
BEFORE BEGINNING TO DRY BACK OUT FOR SUN AND LABOR DAY.
ECMWF/GFS HAVE CONTINUED TO PROG A TROUGH DEVELOPING OVER THE
CANADIAN ROCKIES FRI AND PUSHING OVER THE GREAT LAKES REGION SUN.
WITH THE NOW EXPECTED TROUGHING EXPECTED ACROSS THE REGION FOR THE
SECOND HALF OF THE WEEKEND...TEMPS WILL LIKELY SWING IN THE COOLER
DIRECTION WITH HIGHS IN THE UPR 70S TO POSSIBLY MID 80S FOR LABOR
DAY.
CONFIDENCE...MEDIUM.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* WINDS BCMG NORTH EARLY THIS MORNING AND THEN NE SHORTLY THERE
AFTER.
* MVFR TO IFR CIGS ARE PSBL EARLY THIS MORNING.
* MVFR VSBY IS PSBL LATE TONIGHT INTO THURSDAY MORNING.
JEE
//DISCUSSION...UPDATED 06Z...
A BROAD AREA OF LOW PRESSURE STRETCHES FROM LAKE ONTARIO THROUGH
SOUTHERN WI WITH THE LOWS COLD FRONT FROM SAGINAW MI TO LA CROSSE
WI. THE FRONT WILL CONTINUE TO SINK SOUTH REACHING THE TERMINALS
EARLY THIS MORNING. WINDS WILL BECOME NORTH BEHIND THE FRONT AND
MVFR TO IFR CIGS MAY ACCOMPANY THE FRONTAL PASSAGE. LATEST
GUIDANCE SUGGESTS THE LOWER CIGS WILL NOT MAKE IT SOUTH OF THE
WI/IL STATE LINE AND TRENDS ON SATELLITE WOULD SUPPORT THIS TRAIN
OF THOUGHT. HOWEVER...DID NOT FEEL COMFORTABLE PULLING THE LOWER
CIGS JUST YET SO KEPT IN FEW TO SCT IFR/MVFR CIGS THIS MORNING.
ALSO THINKING VSBY WILL REMAIN VFR ABOVE 6SM THIS MORNING.
WINDS BECOME NE ARND 10 KT THIS MORNING WITH ANY LOWER CLOUD COVER
BURNING OFF BY MID AFTERNOON. ADDED IN THE POSSIBILITY OF MVFR
VSBY LATE TONIGHT AS GUIDANCE AND MODEL SOUNDINGS ARE ALL
SUGGESTING THE LOW LEVELS WILL BE RATHER SATURATED TONIGHT.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN WIND TRENDS...MEDIUM-HIGH CONFIDENCE IN TIMING.
* LOW CONFIDENCE IN MVFR/IFR CIGS. CIGS MAY REMAIN VFR THROUGH THE
PERIOD.
* MEDIUM CONFIDENCE IN REDUCED VSBY LATE TONIGHT.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...VFR.
FRIDAY...CHANCE TSRA...MAINLY FRIDAY EVENING.
SATURDAY...CHANCE TSRA.
SUNDAY...SLIGHT CHANCE TSRA.
MONDAY...VFR.
RC
&&
.MARINE...
242 PM CDT
A BROAD TROUGH STRETCHES ACROSS LAKE MICHIGAN THIS AFTERNOON WITH
GENERALLY SOUTHERLY WINDS ACROSS THE LAKE. AS THE TROUGH SAGS
SOUTHEAST OVER THE NEXT 24 HOURS...WINDS WILL TURN NORTHERLY AS HIGH
PRESSURE BUILDS OVER MINNESOTA AND WISCONSIN WITH WINDS PICKING BACK
UP INTO THE 15 TO 20 KT RANGE. WINDS THEN DIMINISH WEDNESDAY NIGHT
AND THURSDAY AS THE HIGH MOVES OVER LAKE MICHIGAN. ANOTHER FRONT
WILL PASS OVER LAKE MICHIGAN ON SUNDAY...WITH THE GRADIENT
TIGHTENING SUNDAY NIGHT AND MONDAY AS HIGH PRESSURE BUILDS OVER
ONTARIO. WINDS MAY INCREASE FOR A PERIOD INTO THE 30 KT RANGE
MONDAY...THEN DIMINISH MONDAY NIGHT INTO TUESDAY AS THE HIGH
BUILDS SOUTH OVER THE GREAT LAKES.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
112 PM CDT WED AUG 28 2013
.UPDATE...
ISSUED AT 104 PM CDT WED AUG 28 2013
SFC DATA INDICATES THERE IS A PRE-FRONTAL TROF AHEAD OF THE COLD
FRONT. THIS TROF RUNS FROM ROUGHLY KMIW TO SOUTH OF KIKK AS OF
18Z. THE COLD FRONT IS BETWEEN KOLZ AND KALO TO SOUTH OF KVPZ.
SATELLITE TRENDS SHOW THE LOW CLOUDS BREAKING UP BUT STILL IN
PLACE ACROSS THE NORTHERN CWFA. CLOUDS ARE EXPECTED TO REMAIN IN
PLACE FOR MUCH OF THE AFTERNOON WITH A SLOW DISSIPATION. ..08..
UPDATE ISSUED AT 1019 AM CDT WED AUG 28 2013
THE BACK DOOR COOL FRONT IS INTO THE NORTHERN CWFA WITH LOW CLOUDS
IMMEDIATELY BEHIND IT. BASED ON THE 12Z SOUNDING FROM GRB AND
SATELLITE TRENDS...BREAKING UP OF THE CLOUDS OVER THE NORTHERN
CWFA APPEARS QUESTIONABLE THIS AFTERNOON.
AS SUCH...CLOUDS HAVE BEEN INCREASED ACROSS THE NORTH AND
TEMPERATURES LOWERED SOMEWHAT. TEMPERATURES UP NORTH WILL BE
INTERESTING TODAY. IF A SCENARIO SIMILAR TO YESTERDAY IN WISCONSIN
PLAYS OUT THEN SOME AREAS UP NORTH MAY STRUGGLE TO GET MUCH ABOVE
80...OR GET INTO THE 80S AND THEN COLLAPSE BACK INTO THE MID AND
UPPER 70S ONCE THE FRONT MOVES THROUGH.
DIURNAL HEATING AHEAD OF THE FRONT SHOULD SLOW THE SOUTHWARD
PROGRESS OF THE CLOUDS WITH THE FRONT POTENTIALLY STALLING OUT
DURING THE AFTERNOON. CONVERGENCE ALONG THE FRONT IS QUITE WEAK
BUT ONE CANNOT ENTIRELY RULE OUT AN ISOLATED SHOWER OR STORM DUE
TO THE STRONG DIFFERENTIAL HEATING. AS SUCH 10-14 POPS WERE
GENERALLY DONE IN THE VICINITY OF THE FRONT.
THE CURRENT HEAT HEADLINES WILL REMAIN AS IS. THERE ARE QUESTIONS
AS TO WHETHER OR NOT THE NORTHERN EXTEND OF THE ADVISORY AREA WILL
SEE HEAT INDEX READINGS OF 100 DUE TO THE CLOUDS AND FRONTAL
POSITION. ..08..
&&
.SYNOPSIS...
ISSUED AT 341 AM CDT WED AUG 28 2013
MSAS SURFACE ANALYSIS AT 07Z INDICATED THE SURFACE COOL FRONT
REACHING WEST FROM LOW PRESSURE OVER SE LOWER MI ACROSS SOUTHERN
WI...FAR NORTHERN IA...TO A WEAK LOW NW OF VALENTINE NE. SURFACE
DEWPOINTS WERE POOLING IN THE LOWER 70S ALONG AND SOUTH OF THIS AXIS
TO THE HIGHWAY 20 CORRIDOR...WHILE FURTHER SOUTH...MID TO UPPER 60S
WERE COMMON ACROSS THE MUCH OF THE FORECAST AREA. FOG CHANNEL
SATELLITE IMAGERY INDICATED A LARGE FIELD OF POST FRONTAL STRATUS
AND FOG ADVECTING W-SW ACROSS WI...WHILE HINTS OF STRATUS WERE
STARTING TO SHOW UP AHEAD OF THE FRONT BETWEEN KOLZ AND KCGY IN NE
IA. OTHERWISE...IT WAS ANOTHER VERY WARM AND SOMEWHAT MUGGY NIGHT
ACROSS THE REGION WITH TEMPERATURES STILL IN THE MID TO UPPER 70S
AT 3 AM.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT WED AUG 28 2013
MANY CHALLENGES IN THE FORECAST FOR TODAY AS THE TIMING OF FRONT AND
POSSIBLE CLOUDS WILL IMPACT TEMPERATURES...HUMIDITY AND THE HEAT
ADVISORY HEADLINES.
HAVE FOLLOWED A BLEND OF THE 00Z GFS AND ECMWF BRINGING THE FRONT
INTO FAR NW IL AND EAST CENTRAL IA BY LATE MORNING...THEN
STALLING TO ROUGHLY BISECT THE FORECAST AREA FROM NW TO SE BY
EVENING. ASSOCIATED LOW LEVEL MOISTURE CONVERGENCE WILL KEEP
SURFACE DEWPOINTS IN THE LOWER 70S FOR MUCH OF THE DAY ALONG AND
NE OF THE BOUNDARY WITH THERMAL MIXING IN THE LOW LEVEL NE FLOW
EXPECTED TO BE LIMITED TO AROUND 900 MB. ALONG AND SOUTHWEST OF
THE FRONT...ANOTHER DAY OF DEEP MIXING WITH SIMILAR 850 MB
TEMPERATURES AS YESTERDAY SHOULD YIELD SIMILAR HIGHS...WHILE
DEWPOINTS STAY A FEW DEGREES LOWER. BIG QUESTION WILL BE WHAT
HAPPENS WITH THE BACKDOOR POST FRONTAL STRATUS DECK CURRENTLY
RACING TOWARD THE AREA FROM WI...WHICH AT THE PRESENT RATE IS
SHOWN REACHING NW IL BY 7 AM. THE EARLIER RAP RUNS APPEARED TO
HAVE THE BEST HANDLE ON THIS MOIST AXIS AROUND 925 TO 900
MB...SHOWING IT REACHING INTO THE HIGHWAY 20 CORRIDOR EARLY THIS
MORNING...THEN WASHING OUT WITH DAYTIME HEATING AND WILL FOLLOW
THIS SCENARIO FOR NOW COUNTING ON MOSTLY SUNNY SKIES OVER THE
ENTIRE AREA MOST OF THE DAY.
WILL THUS HAVE HIGHS FROM THE MID 80S ACROSS THE NORTHEAST...90 TO
LOWER 90S ACROSS THE CENTRAL THIRD...THEN MID 90S IN THE SOUTH.
THIS MAY AGAIN THREATEN RECORD HIGHS FOR THIS DATE...ESPECIALLY AT
BRL...LISTED IN THE CLIMATE SECTION BELOW. WHEN COMBINED WITH
SURFACE DEWPOINTS LINGERING IN THE LOWER TO MID 70S WHERE THE
FRONT EVENTUALLY STALLS OUT...HEAT INDEX VALUES SHOULD EXCEED 100
BY AFTERNOON. WELL SOUTHWEST OF THE FRONT...DEWPOINTS WILL BE
LOWER...BUT AMBIENT TEMPERATURES INTO THE MID AND POSSIBLY UPPER
90S WILL RESULT IN WIDESPREAD 100 TO 103 HEAT INDEX VALUES IN THE
AFTERNOON. HAVE KEPT THE PREVIOUS HEAT ADVISORY GOING UNTIL 00Z AND
ADDED BUCHANAN AND JONES COUNTY IN EASTERN IA WHERE THE HEAT INDEX
NOW LOOKS LIKELY TO EXCEED 100.
WHILE SOME MODELS ARE ADVERTISING QPF ALONG AND NE OF THE BOUNDARY
TODAY AND TONIGHT...THIS LOOKS OVERDONE GIVEN THE CAPPING WARM
TEMPERATURES ALOFT. THIS CAP WEAKENS SOME TONIGHT...BUT WITH A
STRONG TRIGGER LACKING...WILL KEEP A DRY FORECAST. WITH THE FRONT
LINGERING OVER THE AREA...WARM AND SOMEWHAT HUMID AIR WILL REMAIN IN
PLACE OVER ESPECIALLY THE CENTRAL AND SOUTH. HAVE KEPT LOWS FROM THE
MID 60S NORTHEAST TO THE LOWER 70S ACROSS THE SOUTH.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 341 AM CDT WED AUG 28 2013
FORECAST FOCUS ON HOT AND HUMID AND MAINLY DRY THROUGH SATURDAY...
THEN MUCH COOLER BY LABOR DAY.
THURSDAY THROUGH SATURDAY NIGHT...RIDGING ALOFT AND A CAPPED
ATMOSPHERE TO REMAIN THROUGH MUCH OF THIS TIME FRAME. THERE IS A
SMALL CHANCE OF THUNDERSTORMS MAINLY FRIDAY NIGHT AS A RIDGE RIDER
TRACKS ACROSS THE MIDWEST. THE SURFACE BOUNDARY WILL LIFT BACK TO
THE NORTHEAST OF THE CWA BY FRIDAY. MAXIMUM TEMPERATURES ON THURSDAY
WILL BE IN THE UPPER 80S NORTHEAST TO THE MID 90S SOUTHWEST...AND IN
THE 90S OVER ALL THE CWA BOTH FRIDAY AND SATURDAY. THESE WILL BE
SCORCHERS WITH DEWPOINTS AT LEAST IN THE LOWER 70S. HIGHEST HEAT
INDEX VALUES LOOK TO BE 100 TO 105 IN OUR SOUTHERN COUNTIES ON
THURSDAY...AND OVER MUCH OF THE CWA FOR BOTH FRIDAY AND SATURDAY.
HEAT ADVISORY HEADLINES WILL MORE THAN LIKELY NEED TO BE ISSUED FOR
MUCH OF THIS PERIOD. IF BURLINGTON IOWA RECEIVES NO RAINFALL BY THE
END OF THIS MONTH THEY WILL GO INTO THE BOOKS WITH ONLY A TRACE OF
RAIN FOR THE ENTIRE MONTH OF AUGUST...AND THE DRIEST AUGUST ON
RECORD!
SUNDAY AND SUNDAY NIGHT...TIMING OF THE COLD FRONT WILL BE CRITICAL
AS FAR AS CHANCES FOR THUNDERSTORMS AND MAXIMUM TEMPERATURES. DID
NOTICE THE ECMWF HAS BACKED OFF ON THE REALLY CHILLY AIR FROM A
COUPLE OF RUNS AGO. NOW THE ECMWF BRINGS ONLY THE 8C 850 MB
TEMPERATURE AS FAR SOUTH AS NORTHERN IL INSTEAD OF THE 2C FROM
EARLIER RUNS. CURRENT GRID TEMPERATURES MAY BE TOO WARM ON SUNDAY
DEPENDING ON TIMING OF THE FRONT...AMOUNT OF CLOUD COVER AND ANY
RAINFALL. THERE DOES APPEAR TO BE AT LEAST A CHANCE FOR A FEW
THUNDERSTORMS TO FORM ALONG THE FRONT BUT IN A DRY SPELL YOU DON`T
WANT TO GET YOUR HOPES UP. BUT ONCE AGAIN THIS WILL DEPEND ON THE
TIMING OF THE FRONT AND AMOUNT OF INSTABILITY AND MOISTURE. WELL...
AT LEAST ON PAPER THERE IS ENOUGH FORCING FROM THE DIGGING TROUGH TO
HOPEFULLY TRIGGER AT LEAST SCATTERED STORMS.
NEXT WEEK...HIGH PRESSURE WILL BRING A PLEASANT LABOR DAY AND THE
EARLY PART OF THE SHORTENED WORK WEEK. SHOULD BE A REALLY NICE DAY
FOR GRILLING OUT IN THE BACKYARD. MAXIMUM TEMPERATURES SHOULD END UP
IN THE 70S NORTH AND 80S SOUTH ALONG WITH COMFORTABLE HUMIDITY.
NIGHTTIME LOWS WILL DROP INTO THE 50S TO LOWER 60S EARLY IN THE
WEEK. ACCORDING TO MY FAVORED ECMWF MODEL THERE WILL BE A BRIEF WARM
UP BY MID WEEK FOLLOWED SHORTLY THEREAFTER BY ANOTHER COLD FRONT.
HOWEVER...MUCH OF THE FIRST WEEK OF SEPTEMBER LOOKS ON THE DRY SIDE.
HAASE
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 104 PM CDT WED AUG 28 2013
VFR WX WILL CONTINUE AT KCID/KMLI/KBRL THROUGH 06Z/29. HIGH
PRESSURE WILL CONTINUE TO BUILD INTO THE GREAT LAKES AND SLOWLY
PUSH A COLD FRONT TOWARD SOUTHEAST IOWA. AT KDBQ...MVFR
CONDITIONS WILL SLOWLY IMPROVE TO VFR THROUGH 00Z/29. AFT 06Z/29
LIGHT WINDS AND HIGH LOW LEVEL MOISTURE SHOULD ALLOW MVFR VSBYS TO
DEVELOP. THE POTENTIAL DOES EXIST FOR IFR/LIFR CONDITIONS WITH FOG
PRIOR TO SUNRISE. ..08..
&&
.CLIMATE...
ISSUED AT 341 AM CDT WED AUG 28 2013
RECORD HIGHS FOR AUGUST 28...
MOLINE.........96 IN 1953
CEDAR RAPIDS...96 IN 1955
DUBUQUE........97 IN 1984
BURLINGTON.....96 IN 1945
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR BENTON-BUCHANAN-
CEDAR-DES MOINES-HENRY IA-IOWA-JEFFERSON-JOHNSON-JONES-
KEOKUK-LEE-LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR HANCOCK-HENDERSON-
HENRY IL-MCDONOUGH-MERCER-ROCK ISLAND-WARREN.
MO...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR CLARK-SCOTLAND.
&&
$$
UPDATE...08
SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...12
AVIATION...08
CLIMATE...SHEETS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1028 AM CDT WED AUG 28 2013
.UPDATE...
ISSUED AT 1019 AM CDT WED AUG 28 2013
THE BACK DOOR COOL FRONT IS INTO THE NORTHERN CWFA WITH LOW CLOUDS
IMMEDIATELY BEHIND IT. BASED ON THE 12Z SOUNDING FROM GRB AND
SATELLITE TRENDS...BREAKING UP OF THE CLOUDS OVER THE NORTHERN
CWFA APPEARS QUESTIONABLE THIS AFTERNOON.
AS SUCH...CLOUDS HAVE BEEN INCREASED ACROSS THE NORTH AND
TEMPERATURES LOWERED SOMEWHAT. TEMPERATURES UP NORTH WILL BE
INTERESTING TODAY. IF A SCENARIO SIMILAR TO YESTERDAY IN WISCONSIN
PLAYS OUT THEN SOME AREAS UP NORTH MAY STRUGGLE TO GET MUCH ABOVE
80...OR GET INTO THE 80S AND THEN COLLAPSE BACK INTO THE MID AND
UPPER 70S ONCE THE FRONT MOVES THROUGH.
DIURNAL HEATING AHEAD OF THE FRONT SHOULD SLOW THE SOUTHWARD
PROGRESS OF THE CLOUDS WITH THE FRONT POTENTIALLY STALLING OUT
DURING THE AFTERNOON. CONVERGENCE ALONG THE FRONT IS QUITE WEAK
BUT ONE CANNOT ENTIRELY RULE OUT AN ISOLATED SHOWER OR STORM DUE
TO THE STRONG DIFFERENTIAL HEATING. AS SUCH 10-14 POPS WERE
GENERALLY DONE IN THE VICINITY OF THE FRONT.
THE CURRENT HEAT HEADLINES WILL REMAIN AS IS. THERE ARE QUESTIONS
AS TO WHETHER OR NOT THE NORTHERN EXTEND OF THE ADVISORY AREA WILL
SEE HEAT INDEX READINGS OF 100 DUE TO THE CLOUDS AND FRONTAL
POSITION. ..08..
&&
.SYNOPSIS...
ISSUED AT 341 AM CDT WED AUG 28 2013
MSAS SURFACE ANALYSIS AT 07Z INDICATED THE SURFACE COOL FRONT
REACHING WEST FROM LOW PRESSURE OVER SE LOWER MI ACROSS SOUTHERN
WI...FAR NORTHERN IA...TO A WEAK LOW NW OF VALENTINE NE. SURFACE
DEWPOINTS WERE POOLING IN THE LOWER 70S ALONG AND SOUTH OF THIS AXIS
TO THE HIGHWAY 20 CORRIDOR...WHILE FURTHER SOUTH...MID TO UPPER 60S
WERE COMMON ACROSS THE MUCH OF THE FORECAST AREA. FOG CHANNEL
SATELLITE IMAGERY INDICATED A LARGE FIELD OF POST FRONTAL STRATUS
AND FOG ADVECTING W-SW ACROSS WI...WHILE HINTS OF STRATUS WERE
STARTING TO SHOW UP AHEAD OF THE FRONT BETWEEN KOLZ AND KCGY IN NE
IA. OTHERWISE...IT WAS ANOTHER VERY WARM AND SOMEWHAT MUGGY NIGHT
ACROSS THE REGION WITH TEMPERATURES STILL IN THE MID TO UPPER 70S
AT 3 AM.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT WED AUG 28 2013
MANY CHALLENGES IN THE FORECAST FOR TODAY AS THE TIMING OF FRONT AND
POSSIBLE CLOUDS WILL IMPACT TEMPERATURES...HUMIDITY AND THE HEAT
ADVISORY HEADLINES.
HAVE FOLLOWED A BLEND OF THE 00Z GFS AND ECMWF BRINGING THE FRONT
INTO FAR NW IL AND EAST CENTRAL IA BY LATE MORNING...THEN
STALLING TO ROUGHLY BISECT THE FORECAST AREA FROM NW TO SE BY
EVENING. ASSOCIATED LOW LEVEL MOISTURE CONVERGENCE WILL KEEP
SURFACE DEWPOINTS IN THE LOWER 70S FOR MUCH OF THE DAY ALONG AND
NE OF THE BOUNDARY WITH THERMAL MIXING IN THE LOW LEVEL NE FLOW
EXPECTED TO BE LIMITED TO AROUND 900 MB. ALONG AND SOUTHWEST OF
THE FRONT...ANOTHER DAY OF DEEP MIXING WITH SIMILAR 850 MB
TEMPERATURES AS YESTERDAY SHOULD YIELD SIMILAR HIGHS...WHILE
DEWPOINTS STAY A FEW DEGREES LOWER. BIG QUESTION WILL BE WHAT
HAPPENS WITH THE BACKDOOR POST FRONTAL STRATUS DECK CURRENTLY
RACING TOWARD THE AREA FROM WI...WHICH AT THE PRESENT RATE IS
SHOWN REACHING NW IL BY 7 AM. THE EARLIER RAP RUNS APPEARED TO
HAVE THE BEST HANDLE ON THIS MOIST AXIS AROUND 925 TO 900
MB...SHOWING IT REACHING INTO THE HIGHWAY 20 CORRIDOR EARLY THIS
MORNING...THEN WASHING OUT WITH DAYTIME HEATING AND WILL FOLLOW
THIS SCENARIO FOR NOW COUNTING ON MOSTLY SUNNY SKIES OVER THE
ENTIRE AREA MOST OF THE DAY.
WILL THUS HAVE HIGHS FROM THE MID 80S ACROSS THE NORTHEAST...90 TO
LOWER 90S ACROSS THE CENTRAL THIRD...THEN MID 90S IN THE SOUTH.
THIS MAY AGAIN THREATEN RECORD HIGHS FOR THIS DATE...ESPECIALLY AT
BRL...LISTED IN THE CLIMATE SECTION BELOW. WHEN COMBINED WITH
SURFACE DEWPOINTS LINGERING IN THE LOWER TO MID 70S WHERE THE
FRONT EVENTUALLY STALLS OUT...HEAT INDEX VALUES SHOULD EXCEED 100
BY AFTERNOON. WELL SOUTHWEST OF THE FRONT...DEWPOINTS WILL BE
LOWER...BUT AMBIENT TEMPERATURES INTO THE MID AND POSSIBLY UPPER
90S WILL RESULT IN WIDESPREAD 100 TO 103 HEAT INDEX VALUES IN THE
AFTERNOON. HAVE KEPT THE PREVIOUS HEAT ADVISORY GOING UNTIL 00Z AND
ADDED BUCHANAN AND JONES COUNTY IN EASTERN IA WHERE THE HEAT INDEX
NOW LOOKS LIKELY TO EXCEED 100.
WHILE SOME MODELS ARE ADVERTISING QPF ALONG AND NE OF THE BOUNDARY
TODAY AND TONIGHT...THIS LOOKS OVERDONE GIVEN THE CAPPING WARM
TEMPERATURES ALOFT. THIS CAP WEAKENS SOME TONIGHT...BUT WITH A
STRONG TRIGGER LACKING...WILL KEEP A DRY FORECAST. WITH THE FRONT
LINGERING OVER THE AREA...WARM AND SOMEWHAT HUMID AIR WILL REMAIN IN
PLACE OVER ESPECIALLY THE CENTRAL AND SOUTH. HAVE KEPT LOWS FROM THE
MID 60S NORTHEAST TO THE LOWER 70S ACROSS THE SOUTH.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 341 AM CDT WED AUG 28 2013
FORECAST FOCUS ON HOT AND HUMID AND MAINLY DRY THROUGH SATURDAY...
THEN MUCH COOLER BY LABOR DAY.
THURSDAY THROUGH SATURDAY NIGHT...RIDGING ALOFT AND A CAPPED
ATMOSPHERE TO REMAIN THROUGH MUCH OF THIS TIME FRAME. THERE IS A
SMALL CHANCE OF THUNDERSTORMS MAINLY FRIDAY NIGHT AS A RIDGE RIDER
TRACKS ACROSS THE MIDWEST. THE SURFACE BOUNDARY WILL LIFT BACK TO
THE NORTHEAST OF THE CWA BY FRIDAY. MAXIMUM TEMPERATURES ON THURSDAY
WILL BE IN THE UPPER 80S NORTHEAST TO THE MID 90S SOUTHWEST...AND IN
THE 90S OVER ALL THE CWA BOTH FRIDAY AND SATURDAY. THESE WILL BE
SCORCHERS WITH DEWPOINTS AT LEAST IN THE LOWER 70S. HIGHEST HEAT
INDEX VALUES LOOK TO BE 100 TO 105 IN OUR SOUTHERN COUNTIES ON
THURSDAY...AND OVER MUCH OF THE CWA FOR BOTH FRIDAY AND SATURDAY.
HEAT ADVISORY HEADLINES WILL MORE THAN LIKELY NEED TO BE ISSUED FOR
MUCH OF THIS PERIOD. IF BURLINGTON IOWA RECEIVES NO RAINFALL BY THE
END OF THIS MONTH THEY WILL GO INTO THE BOOKS WITH ONLY A TRACE OF
RAIN FOR THE ENTIRE MONTH OF AUGUST...AND THE DRIEST AUGUST ON
RECORD!
SUNDAY AND SUNDAY NIGHT...TIMING OF THE COLD FRONT WILL BE CRITICAL
AS FAR AS CHANCES FOR THUNDERSTORMS AND MAXIMUM TEMPERATURES. DID
NOTICE THE ECMWF HAS BACKED OFF ON THE REALLY CHILLY AIR FROM A
COUPLE OF RUNS AGO. NOW THE ECMWF BRINGS ONLY THE 8C 850 MB
TEMPERATURE AS FAR SOUTH AS NORTHERN IL INSTEAD OF THE 2C FROM
EARLIER RUNS. CURRENT GRID TEMPERATURES MAY BE TOO WARM ON SUNDAY
DEPENDING ON TIMING OF THE FRONT...AMOUNT OF CLOUD COVER AND ANY
RAINFALL. THERE DOES APPEAR TO BE AT LEAST A CHANCE FOR A FEW
THUNDERSTORMS TO FORM ALONG THE FRONT BUT IN A DRY SPELL YOU DON`T
WANT TO GET YOUR HOPES UP. BUT ONCE AGAIN THIS WILL DEPEND ON THE
TIMING OF THE FRONT AND AMOUNT OF INSTABILITY AND MOISTURE. WELL...
AT LEAST ON PAPER THERE IS ENOUGH FORCING FROM THE DIGGING TROUGH TO
HOPEFULLY TRIGGER AT LEAST SCATTERED STORMS.
NEXT WEEK...HIGH PRESSURE WILL BRING A PLEASANT LABOR DAY AND THE
EARLY PART OF THE SHORTENED WORK WEEK. SHOULD BE A REALLY NICE DAY
FOR GRILLING OUT IN THE BACKYARD. MAXIMUM TEMPERATURES SHOULD END UP
IN THE 70S NORTH AND 80S SOUTH ALONG WITH COMFORTABLE HUMIDITY.
NIGHTTIME LOWS WILL DROP INTO THE 50S TO LOWER 60S EARLY IN THE
WEEK. ACCORDING TO MY FAVORED ECMWF MODEL THERE WILL BE A BRIEF WARM
UP BY MID WEEK FOLLOWED SHORTLY THEREAFTER BY ANOTHER COLD FRONT.
HOWEVER...MUCH OF THE FIRST WEEK OF SEPTEMBER LOOKS ON THE DRY SIDE.
HAASE
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 626 AM CDT WED AUG 28 2013
A COLD FRONT MOVING IN FROM THE NORTH IS INCREASINGLY LOOKING LIKE
IT WILL SPREAD LOW CLOUDS INTO THE DBQ AREA THIS MORNING AND HAVE
ADDED A TEMPO GROUP FOR A CIG BELOW 1000 FT. THESE CLOUDS APPEAR
TO BE THIN AND WILL LIKELY BREAK UP BY MID MORNING TO GIVE WAY TO
PREVAILING VFR CONDITIONS ACROSS THE AREA TODAY. WINDS WILL BE
LIGHT AND GRADUALLY VEER FROM WEST TO NORTHWEST...TO NORTHEAST
WITH THE FRONTAL PASSAGE. TONIGHT...LIGHT WINDS AND LINGERING LOW
LEVEL MOISTURE WILL LIKELY LEAD TO AREAS OF FOG. FOR NOW HAVE
BROUGHT IN PERIODS OF MVFR VISIBILITY TOWARD MORNING. LATER
FORECASTS MAY BRING IN EVEN LOWER VISIBILITIES AS FORECAST
CONFIDENCE INCREASES.
&&
.CLIMATE...
ISSUED AT 341 AM CDT WED AUG 28 2013
RECORD HIGHS FOR AUGUST 28...
MOLINE.........96 IN 1953
CEDAR RAPIDS...96 IN 1955
DUBUQUE........97 IN 1984
BURLINGTON.....96 IN 1945
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR BENTON-BUCHANAN-
CEDAR-DES MOINES-HENRY IA-IOWA-JEFFERSON-JOHNSON-JONES-
KEOKUK-LEE-LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR HANCOCK-HENDERSON-
HENRY IL-MCDONOUGH-MERCER-ROCK ISLAND-WARREN.
MO...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR CLARK-SCOTLAND.
&&
$$
UPDATE...08
SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...12
AVIATION...SHEETS
CLIMATE...SHEETS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
626 AM CDT WED AUG 28 2013
.SYNOPSIS...
ISSUED AT 341 AM CDT WED AUG 28 2013
MSAS SURFACE ANALYSIS AT 07Z INDICATED THE SURFACE COOL FRONT
REACHING WEST FROM LOW PRESSURE OVER SE LOWER MI ACROSS SOUTHERN
WI...FAR NORTHERN IA...TO A WEAK LOW NW OF VALENTINE NE. SURFACE
DEWPOINTS WERE POOLING IN THE LOWER 70S ALONG AND SOUTH OF THIS AXIS
TO THE HIGHWAY 20 CORRIDOR...WHILE FURTHER SOUTH...MID TO UPPER 60S
WERE COMMON ACROSS THE MUCH OF THE FORECAST AREA. FOG CHANNEL
SATELLITE IMAGERY INDICATED A LARGE FIELD OF POST FRONTAL STRATUS
AND FOG ADVECTING W-SW ACROSS WI...WHILE HINTS OF STRATUS WERE
STARTING TO SHOW UP AHEAD OF THE FRONT BETWEEN KOLZ AND KCGY IN NE
IA. OTHERWISE...IT WAS ANOTHER VERY WARM AND SOMEWHAT MUGGY NIGHT
ACROSS THE REGION WITH TEMPERATURES STILL IN THE MID TO UPPER 70S
AT 3 AM.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT WED AUG 28 2013
MANY CHALLENGES IN THE FORECAST FOR TODAY AS THE TIMING OF FRONT AND
POSSIBLE CLOUDS WILL IMPACT TEMPERATURES...HUMIDITY AND THE HEAT
ADVISORY HEADLINES.
HAVE FOLLOWED A BLEND OF THE 00Z GFS AND ECMWF BRINGING THE FRONT
INTO FAR NW IL AND EAST CENTRAL IA BY LATE MORNING...THEN
STALLING TO ROUGHLY BISECT THE FORECAST AREA FROM NW TO SE BY
EVENING. ASSOCIATED LOW LEVEL MOISTURE CONVERGENCE WILL KEEP
SURFACE DEWPOINTS IN THE LOWER 70S FOR MUCH OF THE DAY ALONG AND
NE OF THE BOUNDARY WITH THERMAL MIXING IN THE LOW LEVEL NE FLOW
EXPECTED TO BE LIMITED TO AROUND 900 MB. ALONG AND SOUTHWEST OF
THE FRONT...ANOTHER DAY OF DEEP MIXING WITH SIMILAR 850 MB
TEMPERATURES AS YESTERDAY SHOULD YIELD SIMILAR HIGHS...WHILE
DEWPOINTS STAY A FEW DEGREES LOWER. BIG QUESTION WILL BE WHAT
HAPPENS WITH THE BACKDOOR POST FRONTAL STRATUS DECK CURRENTLY
RACING TOWARD THE AREA FROM WI...WHICH AT THE PRESENT RATE IS
SHOWN REACHING NW IL BY 7 AM. THE EARLIER RAP RUNS APPEARED TO
HAVE THE BEST HANDLE ON THIS MOIST AXIS AROUND 925 TO 900
MB...SHOWING IT REACHING INTO THE HIGHWAY 20 CORRIDOR EARLY THIS
MORNING...THEN WASHING OUT WITH DAYTIME HEATING AND WILL FOLLOW
THIS SCENARIO FOR NOW COUNTING ON MOSTLY SUNNY SKIES OVER THE
ENTIRE AREA MOST OF THE DAY.
WILL THUS HAVE HIGHS FROM THE MID 80S ACROSS THE NORTHEAST...90 TO
LOWER 90S ACROSS THE CENTRAL THIRD...THEN MID 90S IN THE SOUTH.
THIS MAY AGAIN THREATEN RECORD HIGHS FOR THIS DATE...ESPECIALLY AT
BRL...LISTED IN THE CLIMATE SECTION BELOW. WHEN COMBINED WITH
SURFACE DEWPOINTS LINGERING IN THE LOWER TO MID 70S WHERE THE
FRONT EVENTUALLY STALLS OUT...HEAT INDEX VALUES SHOULD EXCEED 100
BY AFTERNOON. WELL SOUTHWEST OF THE FRONT...DEWPOINTS WILL BE
LOWER...BUT AMBIENT TEMPERATURES INTO THE MID AND POSSIBLY UPPER
90S WILL RESULT IN WIDESPREAD 100 TO 103 HEAT INDEX VALUES IN THE
AFTERNOON. HAVE KEPT THE PREVIOUS HEAT ADVISORY GOING UNTIL 00Z AND
ADDED BUCHANAN AND JONES COUNTY IN EASTERN IA WHERE THE HEAT INDEX
NOW LOOKS LIKELY TO EXCEED 100.
WHILE SOME MODELS ARE ADVERTISING QPF ALONG AND NE OF THE BOUNDARY
TODAY AND TONIGHT...THIS LOOKS OVERDONE GIVEN THE CAPPING WARM
TEMPERATURES ALOFT. THIS CAP WEAKENS SOME TONIGHT...BUT WITH A
STRONG TRIGGER LACKING...WILL KEEP A DRY FORECAST. WITH THE FRONT
LINGERING OVER THE AREA...WARM AND SOMEWHAT HUMID AIR WILL REMAIN IN
PLACE OVER ESPECIALLY THE CENTRAL AND SOUTH. HAVE KEPT LOWS FROM THE
MID 60S NORTHEAST TO THE LOWER 70S ACROSS THE SOUTH.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 341 AM CDT WED AUG 28 2013
FORECAST FOCUS ON HOT AND HUMID AND MAINLY DRY THROUGH SATURDAY...
THEN MUCH COOLER BY LABOR DAY.
THURSDAY THROUGH SATURDAY NIGHT...RIDGING ALOFT AND A CAPPED
ATMOSPHERE TO REMAIN THROUGH MUCH OF THIS TIME FRAME. THERE IS A
SMALL CHANCE OF THUNDERSTORMS MAINLY FRIDAY NIGHT AS A RIDGE RIDER
TRACKS ACROSS THE MIDWEST. THE SURFACE BOUNDARY WILL LIFT BACK TO
THE NORTHEAST OF THE CWA BY FRIDAY. MAXIMUM TEMPERATURES ON THURSDAY
WILL BE IN THE UPPER 80S NORTHEAST TO THE MID 90S SOUTHWEST...AND IN
THE 90S OVER ALL THE CWA BOTH FRIDAY AND SATURDAY. THESE WILL BE
SCORCHERS WITH DEWPOINTS AT LEAST IN THE LOWER 70S. HIGHEST HEAT
INDEX VALUES LOOK TO BE 100 TO 105 IN OUR SOUTHERN COUNTIES ON
THURSDAY...AND OVER MUCH OF THE CWA FOR BOTH FRIDAY AND SATURDAY.
HEAT ADVISORY HEADLINES WILL MORE THAN LIKELY NEED TO BE ISSUED FOR
MUCH OF THIS PERIOD. IF BURLINGTON IOWA RECEIVES NO RAINFALL BY THE
END OF THIS MONTH THEY WILL GO INTO THE BOOKS WITH ONLY A TRACE OF
RAIN FOR THE ENTIRE MONTH OF AUGUST...AND THE DRIEST AUGUST ON
RECORD!
SUNDAY AND SUNDAY NIGHT...TIMING OF THE COLD FRONT WILL BE CRITICAL
AS FAR AS CHANCES FOR THUNDERSTORMS AND MAXIMUM TEMPERATURES. DID
NOTICE THE ECMWF HAS BACKED OFF ON THE REALLY CHILLY AIR FROM A
COUPLE OF RUNS AGO. NOW THE ECMWF BRINGS ONLY THE 8C 850 MB
TEMPERATURE AS FAR SOUTH AS NORTHERN IL INSTEAD OF THE 2C FROM
EARLIER RUNS. CURRENT GRID TEMPERATURES MAY BE TOO WARM ON SUNDAY
DEPENDING ON TIMING OF THE FRONT...AMOUNT OF CLOUD COVER AND ANY
RAINFALL. THERE DOES APPEAR TO BE AT LEAST A CHANCE FOR A FEW
THUNDERSTORMS TO FORM ALONG THE FRONT BUT IN A DRY SPELL YOU DON`T
WANT TO GET YOUR HOPES UP. BUT ONCE AGAIN THIS WILL DEPEND ON THE
TIMING OF THE FRONT AND AMOUNT OF INSTABILITY AND MOISTURE. WELL...
AT LEAST ON PAPER THERE IS ENOUGH FORCING FROM THE DIGGING TROUGH TO
HOPEFULLY TRIGGER AT LEAST SCATTERED STORMS.
NEXT WEEK...HIGH PRESSURE WILL BRING A PLEASANT LABOR DAY AND THE
EARLY PART OF THE SHORTENED WORK WEEK. SHOULD BE A REALLY NICE DAY
FOR GRILLING OUT IN THE BACKYARD. MAXIMUM TEMPERATURES SHOULD END UP
IN THE 70S NORTH AND 80S SOUTH ALONG WITH COMFORTABLE HUMIDITY.
NIGHTTIME LOWS WILL DROP INTO THE 50S TO LOWER 60S EARLY IN THE
WEEK. ACCORDING TO MY FAVORED ECMWF MODEL THERE WILL BE A BRIEF WARM
UP BY MID WEEK FOLLOWED SHORTLY THEREAFTER BY ANOTHER COLD FRONT.
HOWEVER...MUCH OF THE FIRST WEEK OF SEPTEMBER LOOKS ON THE DRY SIDE.
HAASE
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 626 AM CDT WED AUG 28 2013
A COLD FRONT MOVING IN FROM THE NORTH IS INCREASINGLY LOOKING LIKE
IT WILL SPREAD LOW CLOUDS INTO THE DBQ AREA THIS MORNING AND HAVE
ADDED A TEMPO GROUP FOR A CIG BELOW 1000 FT. THESE CLOUDS APPEAR
TO BE THIN AND WILL LIKELY BREAK UP BY MID MORNING TO GIVE WAY TO
PREVAILING VFR CONDITIONS ACROSS THE AREA TODAY. WINDS WILL BE
LIGHT AND GRADUALLY VEER FROM WEST TO NORTHWEST...TO NORTHEAST
WITH THE FRONTAL PASSAGE. TONIGHT...LIGHT WINDS AND LINGERING LOW
LEVEL MOISTURE WILL LIKELY LEAD TO AREAS OF FOG. FOR NOW HAVE
BROUGHT IN PERIODS OF MVFR VISIBILITY TOWARD MORNING. LATER
FORECASTS MAY BRING IN EVEN LOWER VISIBILITIES AS FORECAST
CONFIDENCE INCREASES.
&&
.CLIMATE...
ISSUED AT 341 AM CDT WED AUG 28 2013
RECORD HIGHS FOR AUGUST 28...
MOLINE.........96 IN 1953
CEDAR RAPIDS...96 IN 1955
DUBUQUE........97 IN 1984
BURLINGTON.....96 IN 1945
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR BENTON-BUCHANAN-
CEDAR-DES MOINES-HENRY IA-IOWA-JEFFERSON-JOHNSON-JONES-
KEOKUK-LEE-LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR HANCOCK-HENDERSON-
HENRY IL-MCDONOUGH-MERCER-ROCK ISLAND-WARREN.
MO...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR CLARK-SCOTLAND.
&&
$$
SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...12
AVIATION...SHEETS
CLIMATE...SHEETS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
342 AM CDT WED AUG 28 2013
.SYNOPSIS...
ISSUED AT 341 AM CDT WED AUG 28 2013
MSAS SURFACE ANALYSIS AT 07Z INDICATED THE SURFACE COOL FRONT
REACHING WEST FROM LOW PRESSURE OVER SE LOWER MI ACROSS SOUTHERN
WI...FAR NORTHERN IA...TO A WEAK LOW NW OF VALENTINE NE. SURFACE
DEWPOINTS WERE POOLING IN THE LOWER 70S ALONG AND SOUTH OF THIS AXIS
TO THE HIGHWAY 20 CORRIDOR...WHILE FURTHER SOUTH...MID TO UPPER 60S
WERE COMMON ACROSS THE MUCH OF THE FORECAST AREA. FOG CHANNEL
SATELLITE IMAGERY INDICATED A LARGE FIELD OF POST FRONTAL STRATUS
AND FOG ADVECTING W-SW ACROSS WI...WHILE HINTS OF STRATUS WERE
STARTING TO SHOW UP AHEAD OF THE FRONT BETWEEN KOLZ AND KCGY IN NE
IA. OTHERWISE...IT WAS ANOTHER VERY WARM AND SOMEWHAT MUGGY NIGHT
ACROSS THE REGION WITH TEMPERATURES STILL IN THE MID TO UPPER 70S
AT 3 AM.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT WED AUG 28 2013
MANY CHALLENGES IN THE FORECAST FOR TODAY AS THE TIMING OF FRONT AND
POSSIBLE CLOUDS WILL IMPACT TEMPERATURES...HUMIDITY AND THE HEAT
ADVISORY HEADLINES.
HAVE FOLLOWED A BLEND OF THE 00Z GFS AND ECMWF BRINGING THE FRONT
INTO FAR NW IL AND EAST CENTRAL IA BY LATE MORNING...THEN
STALLING TO ROUGHLY BISECT THE FORECAST AREA FROM NW TO SE BY
EVENING. ASSOCIATED LOW LEVEL MOISTURE CONVERGENCE WILL KEEP
SURFACE DEWPOINTS IN THE LOWER 70S FOR MUCH OF THE DAY ALONG AND
NE OF THE BOUNDARY WITH THERMAL MIXING IN THE LOW LEVEL NE FLOW
EXPECTED TO BE LIMITED TO AROUND 900 MB. ALONG AND SOUTHWEST OF
THE FRONT...ANOTHER DAY OF DEEP MIXING WITH SIMILAR 850 MB
TEMPERATURES AS YESTERDAY SHOULD YIELD SIMILAR HIGHS...WHILE
DEWPOINTS STAY A FEW DEGREES LOWER. BIG QUESTION WILL BE WHAT
HAPPENS WITH THE BACKDOOR POST FRONTAL STRATUS DECK CURRENTLY
RACING TOWARD THE AREA FROM WI...WHICH AT THE PRESENT RATE IS
SHOWN REACHING NW IL BY 7 AM. THE EARLIER RAP RUNS APPEARED TO
HAVE THE BEST HANDLE ON THIS MOIST AXIS AROUND 925 TO 900
MB...SHOWING IT REACHING INTO THE HIGHWAY 20 CORRIDOR EARLY THIS
MORNING...THEN WASHING OUT WITH DAYTIME HEATING AND WILL FOLLOW
THIS SCENARIO FOR NOW COUNTING ON MOSTLY SUNNY SKIES OVER THE
ENTIRE AREA MOST OF THE DAY.
WILL THUS HAVE HIGHS FROM THE MID 80S ACROSS THE NORTHEAST...90 TO
LOWER 90S ACROSS THE CENTRAL THIRD...THEN MID 90S IN THE SOUTH.
THIS MAY AGAIN THREATEN RECORD HIGHS FOR THIS DATE...ESPECIALLY AT
BRL...LISTED IN THE CLIMATE SECTION BELOW. WHEN COMBINED WITH
SURFACE DEWPOINTS LINGERING IN THE LOWER TO MID 70S WHERE THE
FRONT EVENTUALLY STALLS OUT...HEAT INDEX VALUES SHOULD EXCEED 100
BY AFTERNOON. WELL SOUTHWEST OF THE FRONT...DEWPOINTS WILL BE
LOWER...BUT AMBIENT TEMPERATURES INTO THE MID AND POSSIBLY UPPER
90S WILL RESULT IN WIDESPREAD 100 TO 103 HEAT INDEX VALUES IN THE
AFTERNOON. HAVE KEPT THE PREVIOUS HEAT ADVISORY GOING UNTIL 00Z AND
ADDED BUCHANAN AND JONES COUNTY IN EASTERN IA WHERE THE HEAT INDEX
NOW LOOKS LIKELY TO EXCEED 100.
WHILE SOME MODELS ARE ADVERTISING QPF ALONG AND NE OF THE BOUNDARY
TODAY AND TONIGHT...THIS LOOKS OVERDONE GIVEN THE CAPPING WARM
TEMPERATURES ALOFT. THIS CAP WEAKENS SOME TONIGHT...BUT WITH A
STRONG TRIGGER LACKING...WILL KEEP A DRY FORECAST. WITH THE FRONT
LINGERING OVER THE AREA...WARM AND SOMEWHAT HUMID AIR WILL REMAIN IN
PLACE OVER ESPECIALLY THE CENTRAL AND SOUTH. HAVE KEPT LOWS FROM THE
MID 60S NORTHEAST TO THE LOWER 70S ACROSS THE SOUTH.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 341 AM CDT WED AUG 28 2013
FORECAST FOCUS ON HOT AND HUMID AND MAINLY DRY THROUGH SATURDAY...
THEN MUCH COOLER BY LABOR DAY.
THURSDAY THROUGH SATURDAY NIGHT...RIDGING ALOFT AND A CAPPED
ATMOSPHERE TO REMAIN THROUGH MUCH OF THIS TIME FRAME. THERE IS A
SMALL CHANCE OF THUNDERSTORMS MAINLY FRIDAY NIGHT AS A RIDGE RIDER
TRACKS ACROSS THE MIDWEST. THE SURFACE BOUNDARY WILL LIFT BACK TO
THE NORTHEAST OF THE CWA BY FRIDAY. MAXIMUM TEMPERATURES ON THURSDAY
WILL BE IN THE UPPER 80S NORTHEAST TO THE MID 90S SOUTHWEST...AND IN
THE 90S OVER ALL THE CWA BOTH FRIDAY AND SATURDAY. THESE WILL BE
SCORCHERS WITH DEWPOINTS AT LEAST IN THE LOWER 70S. HIGHEST HEAT
INDEX VALUES LOOK TO BE 100 TO 105 IN OUR SOUTHERN COUNTIES ON
THURSDAY...AND OVER MUCH OF THE CWA FOR BOTH FRIDAY AND SATURDAY.
HEAT ADVISORY HEADLINES WILL MORE THAN LIKELY NEED TO BE ISSUED FOR
MUCH OF THIS PERIOD. IF BURLINGTON IOWA RECEIVES NO RAINFALL BY THE
END OF THIS MONTH THEY WILL GO INTO THE BOOKS WITH ONLY A TRACE OF
RAIN FOR THE ENTIRE MONTH OF AUGUST...AND THE DRIEST AUGUST ON
RECORD!
SUNDAY AND SUNDAY NIGHT...TIMING OF THE COLD FRONT WILL BE CRITICAL
AS FAR AS CHANCES FOR THUNDERSTORMS AND MAXIMUM TEMPERATURES. DID
NOTICE THE ECMWF HAS BACKED OFF ON THE REALLY CHILLY AIR FROM A
COUPLE OF RUNS AGO. NOW THE ECMWF BRINGS ONLY THE 8C 850 MB
TEMPERATURE AS FAR SOUTH AS NORTHERN IL INSTEAD OF THE 2C FROM
EARLIER RUNS. CURRENT GRID TEMPERATURES MAY BE TOO WARM ON SUNDAY
DEPENDING ON TIMING OF THE FRONT...AMOUNT OF CLOUD COVER AND ANY
RAINFALL. THERE DOES APPEAR TO BE AT LEAST A CHANCE FOR A FEW
THUNDERSTORMS TO FORM ALONG THE FRONT BUT IN A DRY SPELL YOU DON`T
WANT TO GET YOUR HOPES UP. BUT ONCE AGAIN THIS WILL DEPEND ON THE
TIMING OF THE FRONT AND AMOUNT OF INSTABILITY AND MOISTURE. WELL...
AT LEAST ON PAPER THERE IS ENOUGH FORCING FROM THE DIGGING TROUGH TO
HOPEFULLY TRIGGER AT LEAST SCATTERED STORMS.
NEXT WEEK...HIGH PRESSURE WILL BRING A PLEASANT LABOR DAY AND THE
EARLY PART OF THE SHORTENED WORK WEEK. SHOULD BE A REALLY NICE DAY
FOR GRILLING OUT IN THE BACKYARD. MAXIMUM TEMPERATURES SHOULD END UP
IN THE 70S NORTH AND 80S SOUTH ALONG WITH COMFORTABLE HUMIDITY.
NIGHTTIME LOWS WILL DROP INTO THE 50S TO LOWER 60S EARLY IN THE
WEEK. ACCORDING TO MY FAVORED ECMWF MODEL THERE WILL BE A BRIEF WARM
UP BY MID WEEK FOLLOWED SHORTLY THEREAFTER BY ANOTHER COLD FRONT.
HOWEVER...MUCH OF THE FIRST WEEK OF SEPTEMBER LOOKS ON THE DRY SIDE.
HAASE
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY EVENING)
ISSUED AT 1143 PM CDT TUE AUG 27 2013
6 KTS WEST TO SOUTHWEST WILL CONTINUE THROUGH LATE NIGHT...THEN AS
A WEAK FRONT APPROACHES FROM THE NORTH WEDNESDAY MORNING...WINDS
WILL BECOME VERY LIGHT FROM THE NORTHEAST TO EAST. CLEAR SKIES
OVERNIGHT WILL EVENTUALLY GIVE WAY TO SOME 3500 FT STRATOCUMULUS
NORTH...WHICH AT THIS POINT SHOULD BE SCATTERED AND VFR.
HOWEVER...THIS TREND WILL BE WATCHED FOR A POTENTIAL RISK FOR MVFR
STRATUS WEDNESDAY MORNING. IT REMAINS THE ONLY THREAT TO AVIATION
WEATHER...THOUGH LOW AT THIS TIME. ERVIN
&&
.CLIMATE...
ISSUED AT 341 AM CDT WED AUG 28 2013
RECORD HIGHS FOR AUGUST 28...
MOLINE.........96 IN 1953
CEDAR RAPIDS...96 IN 1955
DUBUQUE........97 IN 1984
BURLINGTON.....96 IN 1945
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR BENTON-BUCHANAN-
CEDAR-DES MOINES-HENRY IA-IOWA-JEFFERSON-JOHNSON-JONES-
KEOKUK-LEE-LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR HANCOCK-HENDERSON-
HENRY IL-MCDONOUGH-MERCER-ROCK ISLAND-WARREN.
MO...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR CLARK-SCOTLAND.
&&
$$
SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...12
AVIATION...ERVIN
CLIMATE...SHEETS
AREA FORECAST DISCUSSION
NWS JACKSON KY
1044 AM EDT WED AUG 28 2013
.UPDATE...
ISSUED AT 1044 AM EDT WED AUG 28 2013
UPDATED THE FORECAST TO BETTER REFLECT CURRENT CONDITIONS AND MODEL
TRENDS. THE AIR OVER EASTERN KENTUCKY IS ONCE AGAIN UNSTABLE AND AS
YESTERDAY IS LOOKING FOR A TRIGGER TO GET THINGS GOING. NOT SEEING
ANYTHING DEFINITE...HOWEVER BY THE END OF THE DAY...THE FRONT WILL BE
GETTING CLOSER AND THIS COULD HELP TO GET SOME CONVECTION GOING IN
THIS PREFRONTAL ENVIRONMENT. THE MODELS WERE SHOWING SOME DECREASE IN
CLOUDS THIS AFTERNOON AND SO BUMPED THE HIGHS UP A LITTLE. ALSO MADE
SOME SLIGHT ADJUSTMENTS IN FOR TONIGHT AND TOMORROW BASED ON THE
LATEST MODELS.
UPDATE ISSUED AT 651 AM EDT WED AUG 28 2013
A FEW WIDELY ISOLATED SHOWERS ARE DEVELOPING ACROSS SOUTHEAST PIKE
COUNTY. COVERAGE IS VERY SMALL AT THIS TIME AND STORM MOVEMENT WILL
TAKE THIS ACTIVITY SOUTHEAST OF THE AREA IN THE NEXT HOUR. THUS...NO
PLANS TO INTRODUCE POPS AT THIS TIME. WILL MAKE SOME TWEAKS TO THE
HOURLY POPS TO ACCOUNT FOR THIS ACTIVITY. OTHERWISE...HRRR CONTINUES
TO SHOW A SIGNIFICANT LULL FOR THE AREA TODAY WITH A BAND OF ISOLATED
TO PERHAPS SCATTERED SHOWERS ARRIVING LATE (AFTER 20Z) IN THE DAY
FROM THE NORTH. GOING TO DEAL WITH SOME CLOUD COVER THIS MORNING FROM
THE DEBRIS OF AN OVERNIGHT MCS THAT WILL DRIFT SOUTH ACROSS THE AREA.
HOWEVER...CLOUD COVER SHOULD GIVE WAY TO A GOOD DOSE OF SUNSHINE BY
MID TO LATE MORNING...ALLOWING FOR THE ANTICIPATED WARM DAY. NO
UPDATE PLANNED AT THIS TIME...BUT AS MENTIONED...WILL FRESHEN UP THE
HOURLY GRIDS.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 307 AM EDT WED AUG 28 2013
A STRONG RIDGE CONTINUES TO DOMINATE FROM THE SOUTH CENTRAL US INTO
THE CENTRAL PLAINS. PRESENTLY...A SHORTWAVE ON THE PERIPHERALS OF THIS
RIDGE IS PUSHING SOUTHEAST ACROSS THE SOUTHERN GREAT LAKES. THIS WAVE
WILL BE THE FOCUS OF OUR WEATHER TODAY AS IT BRINGS A THREAT OF
SHOWERS AND A FEW THUNDERSTORMS BACK TO THE AREA. MODELS ALL HAVE
THIS SHORTWAVE PROGRESSING SOUTHEAST ACROSS THE EASTERN OHIO RIVER
VALLEY TODAY. HOWEVER...THERE ARE SOME DIFFERENCES ON EXACTLY HOW FAR
SOUTHWEST THIS SHORTWAVE WILL TRACK...AND ULTIMATELY...HOW FAR
SOUTHWEST THE HIGHER CHANCES FOR RAIN WILL REACH. 00Z NAM IS THE MOST
AGGRESSIVE BRINGING SCATTERED TO NUMEROUS SHOWERS ACROSS THE COAL
FIELDS TODAY. HOWEVER...LATEST HRRR DOESN`T SEEM TO SUPPORT THE NAM
EVEN TO A LITTLE DEGREE. MEANWHILE...THE ECMWF AND GFS BOTH SUGGEST
PRECIPITATION WILL BE CONFINED TO THE EASTERN MOST COUNTIES IN
KENTUCKY TODAY. GIVEN THE UNCERTAINTY...HARD TO GO VERY HIGH WITH THE
CHANCE OF RAIN TODAY...ESPECIALLY THE FARTHER WEST YOU GET. BEST
SHORTWAVE ENERGY PROBABLY WILL NOT ARRIVE UNTIL LATE IN THE DAY...SO
HAVE DELAYED POPS INTO THE EVENING HOURS...AND GONE WITH 20 PERCENT
CHANCES IN THE WEST TO 40 PERCENT IN THE FAR EAST. THERE IS A PRETTY
GOOD CHANCE THAT THESE POPS MAY BE TOO HIGH AS WE MAY HAVE A TOUGH
TIME GETTING DECENT COVERAGE. HIGHS TODAY WILL CLIMB INTO THE MID TO
UPPER 80S (AROUND 1 TO 2 DEGREES WARMER THAN YESTERDAY).
GOING TO MAINTAIN SOME SLIGHT POPS TONIGHT AS A WEAK BOUNDARY
ASSOCIATED WITH THE SHORTWAVE CONTINUES TO SAG SOUTHWARD. THIS
BOUNDARY SHOULD EXIT THE SOUTH ON THURSDAY...ALLOWING FOR A RAIN FREE
DAY. AN ISOLATED SHOWER COULD POP UP ALONG THE VIRGINIA OR TENNESSEE
BORDER BY LATE MORNING PRIOR TO THIS FRONT CLEARING THE AREA.
DESPITE THE BOUNDARY SAGGING SOUTH...TEMPERATURES WILL REMAIN JUST AS
WARM WITH HIGHS INTO THE MID TO UPPER 80S.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 307 AM EDT WED AUG 28 2013
THE UPPER LEVEL PATTERN DURING THE PERIOD WILL FEATURE A STRONG
UPPER LEVEL HIGH CENTERED NEAR THE TX/OK PANHANDLES...WITH TROUGHING
ON EITHER SIDE. THE AMPLITUDE OF THE PATTERN WILL FLUCTUATE AS UPPER
LOWS RIDE THROUGH THE WESTERLIES AROUND THE RIDGE. DEAMPLIFICATION
IS EXPECTED EARLY IN THE PERIOD...WITH REAMPLIFICATION TOWARD THE
END. THIS SET-UP PUTS OUR LOCAL AREA IN A GENERAL NW FLOW
ALOFT...FAVORING PERIODIC COLD FRONTAL PASSAGES. ONE FRONT WILL BE
EXITING TO OUR S AND SW AT THE START OF THE PERIOD. SLIGHTLY DRIER
AIR BEHIND THE FRONT SHOULD ALLOW FOR DRY WEATHER THROUGH FRIDAY
NIGHT.
THE FRONT WILL STALL AND WEAKEN AFTER IT PASSES...AND MORE HUMID AIR
WILL BE LOOMING JUST TO OUR S AND W. AS SURFACE HIGH PRESSURE
SLIPS AWAY TO OUR EAST...LOW LEVEL FLOW WILL SEND THIS AIR MASS BACK
INTO OUR AREA DURING THE WEEKEND. MODELS DO SHOW WEAK DISTURBANCES
ALOFT TRAVELING IN THE NW FLOW. COMBINED WITH INCREASING MOISTURE
AND WEAK ISENTROPIC LIFT...THIS MAY VERY WELL ALLOW SCATTERED
SHOWERS AND THUNDERSTORMS TO DEVELOP...AND 30-40 PERCENT POPS WILL
BE USED DURING THE WEEKEND.
AS THE NEXT UPPER LOW HEADS INTO THE GENERALIZED EAST CONUS
TROUGH...PATTERN AMPLIFICATION BEGINS BEFORE THE WEEKEND IS
FINISHED...AND THE REJUVENATED EAST CONUS TROUGH BRINGS ANOTHER COLD
FRONT SOUTHEAST TO OUR AREA. OUR BEST CHANCE AT PRECIP IS WITH
HEATING JUST AHEAD OF THE FRONT ON MONDAY. WILL STICK WITH HIGH
CHANCE POPS AT THIS POINT. THE BEST ESTIMATE FOR FROPA IS MONDAY
NIGHT AND POSSIBLY INTO EARLY TUESDAY. ANY PRECIP SHOULD END NW TO
SE AS DRIER AIR ARRIVES BEHIND THE FRONT. MODELS HAVE NOT BEEN
CONSISTENT CONCERNING THE DEGREE OF COOLING/DRYING BEHIND THIS
FRONT...AND A MODEL BLEND/AVERAGE WILL BE USED.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 651 AM EDT WED AUG 28 2013
AN AREA OF 800-1000 FT STRATUS HAS FORMED OVER MUCH OF THE AREA THIS
MORNING ALONG WITH SOME PATCHY FOG. THE FOG/STRATUS MAY LINGER A BIT
LONGER THAN THE PAST FEW MORNINGS AS WE HAVE SOME MID/HIGH CLOUDS
DRIFTING IN FROM THE NORTH WHICH MAY SLOW THE WARMING PROCESS THIS
MORNING. WE SHOULD SEE THINGS RETURN TO MAINLY VFR BY MID TO LATE
MORNING AS TEMPERATURES FINALLY START TO WARM AND WE MIX OUT THE LOW
CLOUDS. A BAND OF ISOLATED SHOWERS MAY WORK INTO THE AREA LATE IN THE
DAY AND COULD AFFECT THE TAF SITES...BUT COVERAGE WILL BE VERY
LIMITED AND WILL NOT INTRODUCE SHOWERS AT THIS TIME. AS A WEAK
FRONTAL BOUNDARY PUSHES SOUTH LATE TONIGHT...ANOTHER ROUND OF VALLEY
FOG MAY BE POSSIBLE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJ
SHORT TERM...KAS
LONG TERM...HAL
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS JACKSON KY
651 AM EDT WED AUG 28 2013
.UPDATE...
ISSUED AT 651 AM EDT WED AUG 28 2013
A FEW WIDELY ISOLATED SHOWERS ARE DEVELOPING ACROSS SOUTHEAST PIKE
COUNTY. COVERAGE IS VERY SMALL AT THIS TIME AND STORM MOVEMENT WILL
TAKE THIS ACTIVITY SOUTHEAST OF THE AREA IN THE NEXT HOUR. THUS...NO
PLANS TO INTRODUCE POPS AT THIS TIME. WILL MAKE SOME TWEAKS TO THE
HOURLY POPS TO ACCOUNT FOR THIS ACTIVITY. OTHERWISE...HRRR CONTINUES
TO SHOW A SIGNIFICANT LULL FOR THE AREA TODAY WITH A BAND OF ISOLATED
TO PERHAPS SCATTERED SHOWERS ARRIVING LATE (AFTER 20Z) IN THE DAY
FROM THE NORTH. GOING TO DEAL WITH SOME CLOUD COVER THIS MORNING FROM
THE DEBRIS OF AN OVERNIGHT MCS THAT WILL DRIFT SOUTH ACROSS THE AREA.
HOWEVER...CLOUD COVER SHOULD GIVE WAY TO A GOOD DOSE OF SUNSHINE BY
MID TO LATE MORNING...ALLOWING FOR THE ANTICIPATED WARM DAY. NO
UPDATE PLANNED AT THIS TIME...BUT AS MENTIONED...WILL FRESHEN UP THE
HOURLY GRIDS.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 307 AM EDT WED AUG 28 2013
A STRONG RIDGE CONTINUES TO DOMINATE FROM THE SOUTH CENTRAL US INTO
THE CENTRAL PLAINS. PRESENTLY...A SHORTWAVE ON THE PERIPHERALS OF THIS
RIDGE IS PUSHING SOUTHEAST ACROSS THE SOUTHERN GREAT LAKES. THIS WAVE
WILL BE THE FOCUS OF OUR WEATHER TODAY AS IT BRINGS A THREAT OF
SHOWERS AND A FEW THUNDERSTORMS BACK TO THE AREA. MODELS ALL HAVE
THIS SHORTWAVE PROGRESSING SOUTHEAST ACROSS THE EASTERN OHIO RIVER
VALLEY TODAY. HOWEVER...THERE ARE SOME DIFFERENCES ON EXACTLY HOW FAR
SOUTHWEST THIS SHORTWAVE WILL TRACK...AND ULTIMATELY...HOW FAR
SOUTHWEST THE HIGHER CHANCES FOR RAIN WILL REACH. 00Z NAM IS THE MOST
AGGRESSIVE BRINGING SCATTERED TO NUMEROUS SHOWERS ACROSS THE COAL
FIELDS TODAY. HOWEVER...LATEST HRRR DOESN`T SEEM TO SUPPORT THE NAM
EVEN TO A LITTLE DEGREE. MEANWHILE...THE ECMWF AND GFS BOTH SUGGEST
PRECIPITATION WILL BE CONFINED TO THE EASTERN MOST COUNTIES IN
KENTUCKY TODAY. GIVEN THE UNCERTAINTY...HARD TO GO VERY HIGH WITH THE
CHANCE OF RAIN TODAY...ESPECIALLY THE FARTHER WEST YOU GET. BEST
SHORTWAVE ENERGY PROBABLY WILL NOT ARRIVE UNTIL LATE IN THE DAY...SO
HAVE DELAYED POPS INTO THE EVENING HOURS...AND GONE WITH 20 PERCENT
CHANCES IN THE WEST TO 40 PERCENT IN THE FAR EAST. THERE IS A PRETTY
GOOD CHANCE THAT THESE POPS MAY BE TOO HIGH AS WE MAY HAVE A TOUGH
TIME GETTING DECENT COVERAGE. HIGHS TODAY WILL CLIMB INTO THE MID TO
UPPER 80S (AROUND 1 TO 2 DEGREES WARMER THAN YESTERDAY).
GOING TO MAINTAIN SOME SLIGHT POPS TONIGHT AS A WEAK BOUNDARY
ASSOCIATED WITH THE SHORTWAVE CONTINUES TO SAG SOUTHWARD. THIS
BOUNDARY SHOULD EXIT THE SOUTH ON THURSDAY...ALLOWING FOR A RAIN FREE
DAY. AN ISOLATED SHOWER COULD POP UP ALONG THE VIRGINIA OR TENNESSEE
BORDER BY LATE MORNING PRIOR TO THIS FRONT CLEARING THE AREA.
DESPITE THE BOUNDARY SAGGING SOUTH...TEMPERATURES WILL REMAIN JUST AS
WARM WITH HIGHS INTO THE MID TO UPPER 80S.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 307 AM EDT WED AUG 28 2013
THE UPPER LEVEL PATTERN DURING THE PERIOD WILL FEATURE A STRONG
UPPER LEVEL HIGH CENTERED NEAR THE TX/OK PANHANDLES...WITH TROUGHING
ON EITHER SIDE. THE AMPLITUDE OF THE PATTERN WILL FLUCTUATE AS UPPER
LOWS RIDE THROUGH THE WESTERLIES AROUND THE RIDGE. DEAMPLIFICATION
IS EXPECTED EARLY IN THE PERIOD...WITH REAMPLIFICATION TOWARD THE
END. THIS SET-UP PUTS OUR LOCAL AREA IN A GENERAL NW FLOW
ALOFT...FAVORING PERIODIC COLD FRONTAL PASSAGES. ONE FRONT WILL BE
EXITING TO OUR S AND SW AT THE START OF THE PERIOD. SLIGHTLY DRIER
AIR BEHIND THE FRONT SHOULD ALLOW FOR DRY WEATHER THROUGH FRIDAY
NIGHT.
THE FRONT WILL STALL AND WEAKEN AFTER IT PASSES...AND MORE HUMID AIR
WILL BE LOOMING JUST TO OUR S AND W. AS SURFACE HIGH PRESSURE
SLIPS AWAY TO OUR EAST...LOW LEVEL FLOW WILL SEND THIS AIR MASS BACK
INTO OUR AREA DURING THE WEEKEND. MODELS DO SHOW WEAK DISTURBANCES
ALOFT TRAVELING IN THE NW FLOW. COMBINED WITH INCREASING MOISTURE
AND WEAK ISENTROPIC LIFT...THIS MAY VERY WELL ALLOW SCATTERED
SHOWERS AND THUNDERSTORMS TO DEVELOP...AND 30-40 PERCENT POPS WILL
BE USED DURING THE WEEKEND.
AS THE NEXT UPPER LOW HEADS INTO THE GENERALIZED EAST CONUS
TROUGH...PATTERN AMPLIFICATION BEGINS BEFORE THE WEEKEND IS
FINISHED...AND THE REJUVENATED EAST CONUS TROUGH BRINGS ANOTHER COLD
FRONT SOUTHEAST TO OUR AREA. OUR BEST CHANCE AT PRECIP IS WITH
HEATING JUST AHEAD OF THE FRONT ON MONDAY. WILL STICK WITH HIGH
CHANCE POPS AT THIS POINT. THE BEST ESTIMATE FOR FROPA IS MONDAY
NIGHT AND POSSIBLY INTO EARLY TUESDAY. ANY PRECIP SHOULD END NW TO
SE AS DRIER AIR ARRIVES BEHIND THE FRONT. MODELS HAVE NOT BEEN
CONSISTENT CONCERNING THE DEGREE OF COOLING/DRYING BEHIND THIS
FRONT...AND A MODEL BLEND/AVERAGE WILL BE USED.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 651 AM EDT WED AUG 28 2013
AN AREA OF 800-1000 FT STRATUS HAS FORMED OVER MUCH OF THE AREA THIS
MORNING ALONG WITH SOME PATCHY FOG. THE FOG/STRATUS MAY LINGER A BIT
LONGER THAN THE PAST FEW MORNINGS AS WE HAVE SOME MID/HIGH CLOUDS
DRIFTING IN FROM THE NORTH WHICH MAY SLOW THE WARMING PROCESS THIS
MORNING. WE SHOULD SEE THINGS RETURN TO MAINLY VFR BY MID TO LATE
MORNING AS TEMPERATURES FINALLY START TO WARM AND WE MIX OUT THE LOW
CLOUDS. A BAND OF ISOLATED SHOWERS MAY WORK INTO THE AREA LATE IN THE
DAY AND COULD AFFECT THE TAF SITES...BUT COVERAGE WILL BE VERY
LIMITED AND WILL NOT INTRODUCE SHOWERS AT THIS TIME. AS A WEAK
FRONTAL BOUNDARY PUSHES SOUTH LATE TONIGHT...ANOTHER ROUND OF VALLEY
FOG MAY BE POSSIBLE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...KAS
LONG TERM...HAL
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS JACKSON KY
308 AM EDT WED AUG 28 2013
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 307 AM EDT WED AUG 28 2013
A STRONG RIDGE CONTINUES TO DOMINATE FROM THE SOUTH CENTRAL US INTO
THE CENTRAL PLAINS. PRESENTLY...A SHORTWAVE ON THE PERIPHERALS OF THIS
RIDGE IS PUSHING SOUTHEAST ACROSS THE SOUTHERN GREAT LAKES. THIS WAVE
WILL BE THE FOCUS OF OUR WEATHER TODAY AS IT BRINGS A THREAT OF
SHOWERS AND A FEW THUNDERSTORMS BACK TO THE AREA. MODELS ALL HAVE
THIS SHORTWAVE PROGRESSING SOUTHEAST ACROSS THE EASTERN OHIO RIVER
VALLEY TODAY. HOWEVER...THERE ARE SOME DIFFERENCES ON EXACTLY HOW FAR
SOUTHWEST THIS SHORTWAVE WILL TRACK...AND ULTIMATELY...HOW FAR
SOUTHWEST THE HIGHER CHANCES FOR RAIN WILL REACH. 00Z NAM IS THE MOST
AGGRESSIVE BRINGING SCATTERED TO NUMEROUS SHOWERS ACROSS THE COAL
FIELDS TODAY. HOWEVER...LATEST HRRR DOESN`T SEEM TO SUPPORT THE NAM
EVEN TO A LITTLE DEGREE. MEANWHILE...THE ECMWF AND GFS BOTH SUGGEST
PRECIPITATION WILL BE CONFINED TO THE EASTERN MOST COUNTIES IN
KENTUCKY TODAY. GIVEN THE UNCERTAINTY...HARD TO GO VERY HIGH WITH THE
CHANCE OF RAIN TODAY...ESPECIALLY THE FARTHER WEST YOU GET. BEST
SHORTWAVE ENERGY PROBABLY WILL NOT ARRIVE UNTIL LATE IN THE DAY...SO
HAVE DELAYED POPS INTO THE EVENING HOURS...AND GONE WITH 20 PERCENT
CHANCES IN THE WEST TO 40 PERCENT IN THE FAR EAST. THERE IS A PRETTY
GOOD CHANCE THAT THESE POPS MAY BE TOO HIGH AS WE MAY HAVE A TOUGH
TIME GETTING DECENT COVERAGE. HIGHS TODAY WILL CLIMB INTO THE MID TO
UPPER 80S (AROUND 1 TO 2 DEGREES WARMER THAN YESTERDAY).
GOING TO MAINTAIN SOME SLIGHT POPS TONIGHT AS A WEAK BOUNDARY
ASSOCIATED WITH THE SHORTWAVE CONTINUES TO SAG SOUTHWARD. THIS
BOUNDARY SHOULD EXIT THE SOUTH ON THURSDAY...ALLOWING FOR A RAIN FREE
DAY. AN ISOLATED SHOWER COULD POP UP ALONG THE VIRGINIA OR TENNESSEE
BORDER BY LATE MORNING PRIOR TO THIS FRONT CLEARING THE AREA.
DESPITE THE BOUNDARY SAGGING SOUTH...TEMPERATURES WILL REMAIN JUST AS
WARM WITH HIGHS INTO THE MID TO UPPER 80S.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 307 AM EDT WED AUG 28 2013
THE UPPER LEVEL PATTERN DURING THE PERIOD WILL FEATURE A STRONG
UPPER LEVEL HIGH CENTERED NEAR THE TX/OK PANHANDLES...WITH TROUGHING
ON EITHER SIDE. THE AMPLITUDE OF THE PATTERN WILL FLUCTUATE AS UPPER
LOWS RIDE THROUGH THE WESTERLIES AROUND THE RIDGE. DEAMPLIFICATION
IS EXPECTED EARLY IN THE PERIOD...WITH REAMPLIFICATION TOWARD THE
END. THIS SET-UP PUTS OUR LOCAL AREA IN A GENERAL NW FLOW
ALOFT...FAVORING PERIODIC COLD FRONTAL PASSAGES. ONE FRONT WILL BE
EXITING TO OUR S AND SW AT THE START OF THE PERIOD. SLIGHTLY DRIER
AIR BEHIND THE FRONT SHOULD ALLOW FOR DRY WEATHER THROUGH FRIDAY
NIGHT.
THE FRONT WILL STALL AND WEAKEN AFTER IT PASSES...AND MORE HUMID AIR
WILL BE LOOMING JUST TO OUR S AND W. AS SURFACE HIGH PRESSURE
SLIPS AWAY TO OUR EAST...LOW LEVEL FLOW WILL SEND THIS AIR MASS BACK
INTO OUR AREA DURING THE WEEKEND. MODELS DO SHOW WEAK DISTURBANCES
ALOFT TRAVELING IN THE NW FLOW. COMBINED WITH INCREASING MOISTURE
AND WEAK ISENTROPIC LIFT...THIS MAY VERY WELL ALLOW SCATTERED
SHOWERS AND THUNDERSTORMS TO DEVELOP...AND 30-40 PERCENT POPS WILL
BE USED DURING THE WEEKEND.
AS THE NEXT UPPER LOW HEADS INTO THE GENERALIZED EAST CONUS
TROUGH...PATTERN AMPLIFICATION BEGINS BEFORE THE WEEKEND IS
FINISHED...AND THE REJUVENATED EAST CONUS TROUGH BRINGS ANOTHER COLD
FRONT SOUTHEAST TO OUR AREA. OUR BEST CHANCE AT PRECIP IS WITH
HEATING JUST AHEAD OF THE FRONT ON MONDAY. WILL STICK WITH HIGH
CHANCE POPS AT THIS POINT. THE BEST ESTIMATE FOR FROPA IS MONDAY
NIGHT AND POSSIBLY INTO EARLY TUESDAY. ANY PRECIP SHOULD END NW TO
SE AS DRIER AIR ARRIVES BEHIND THE FRONT. MODELS HAVE NOT BEEN
CONSISTENT CONCERNING THE DEGREE OF COOLING/DRYING BEHIND THIS
FRONT...AND A MODEL BLEND/AVERAGE WILL BE USED.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 200 AM EDT WED AUG 28 2013
PATCHY VALLEY FOG IS EXPECTED AGAIN TONIGHT...LEADING TO SLIGHT
REDUCTIONS IN VISIBILITIES AT KLOZ AND KSME. OTHERWISE...VFR
CONDITIONS WILL CONTINUE THROUGH THIS EVENING. A WEATHER DISTURBANCE
WILL DROP SOUTH LATE IN THE DAY AND COULD GENERATE A FEW SHOWERS.
HOWEVER...CONFIDENCE IS LOW AS TO HOW FAR WEST THESE SHOWERS WILL
REACH...SO HAVE OPTED TO NOT INCLUDE IN THE TAFS AT THIS POINT.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...KAS
LONG TERM...HAL
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1029 AM EDT WED AUG 28 2013
.SYNOPSIS...
SHOWERS AND THUNDERSTORMS...SOME WITH HEAVY RAIN...WILL BE
EXPECTED THROUGH THE AFTERNOON AS AN UPPER LEVEL DISTURBANCE
PUSHES A FRONT SOUTHEASTWARD ACROSS THE REGION. HIGH PRESSURE
BUILDS OVERHEAD FOR THE REST OF THE WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AN UPDATE WAS MADE TO ADDRESS THE NEWLY ISSUED FLASH FLOOD WATCH
FOR PRESTON...TUCKER...GARRETT...AND THE WESTMORELAND/FAYETTE
RIDGES THROUGH THIS EVENING. THESE COUNTIES HAVE ALREADY RECEIVED
TWO TO THREE INCHES OF RAIN FROM THE SYSTEM OVERNIGHT...BRINGING
THEM CLOSE TO FLASH FLOOD GUIDANCE ALREADY. WITH THE HRRR AND
OTHER HI RES MODELS SUGGESTING THAT ADDITIONAL SHOWERS AND
THUNDERSTORMS WILL REDEVELOP ALONG THE BOUNDARY PROGGED TO CROSS
BY EARLY AFTERNOON...FELT IT BEST TO ADDRESS THIS WITH A WATCH.
CONTINUED TO CARRY LIKELY POPS FOR THE COUNTIES IN NORTHERN PA
THROUGH THIS AFTERNOON WITH THE SHORTWAVE AND SURFACE LOW MOVING
SLOWLY SOUTHEASTWARD. WITH PWAT VALUES REMAINING CLOSE TO THE 2
INCH RANGE...IT IS NOT OUT OF THE QUESTION THAT THERE COULD
LOCALIZED FLOODING ISSUES. BUT SINCE THESE AREAS WERE NOT PRIMED
WITH RAINFALL FROM YESTERDAY AFTERNOON...OPTED TO LEAVE THEM OUT
OF A WATCH AT THIS TIME.
CONDITIONS SHOULD IMPROVE BY LATE THIS AFTERNOON AS THE WEAK FRONT
DEPARTS SOUTHWARD. WEAK HIGH PRESSURE WILL BUILD OVERHEAD
OVERNIGHT.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
NORTHWEST FLOW ALOFT WILL REMAIN IN PLACE WHILE WEAK SURFACE RIDGE
KEEPS REGION DRY THROUGH THE PERIOD. WHILE DEW POINTS WILL BE
LOWER THAN TODAY...THEY WILL REMAIN ABOVE 60F FOR THE MOST PART
WITH TEMPERATURES RUNNING NEAR 5 DEGREES ABOVE AVERAGE.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
SHWR AND TSTM CHCS BEGIN TO INCRS AGAIN FRI NGT AND SAT AS A WRMFNT
APPRCHS FM THE SW. THE FNT SHOULD SHIFT NE ON SUN...HOWEVER SCT
CNVCTN IS STILL PSBL ESP IN THE AFTN. A CDFNT IS PROGGED TO MOVE
THRU ON MON WITH THE BEST CHC FOR SHWRS AND TSTMS. DRY WEA AND HIGH
PRES RTN AFT FROPA. TEMPS EXPD TO BE ABV SEASONAL AVGS UNTIL THE MON
CDFNT PASSAGE BRINGS A LTL BLO AVG TEMPS.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
AMPLE MOISTURE COMBINED WITH AN APPRCHG FRONTAL BNDRY WL CONT TO
BRING MVFR/ISOLD IFR IN SHWRS AND ISOLD TSTMS TO THE AREA THRU THE
MRNG. AS MOISTURE BEGINS TO SHIFT SWD...EXP AN END TO THE MORE
WDSPRD SHWRS GRDLY FM N-S...HOWEVER SCT SHWRS OR A TSTM WL STILL BE
PSBL INTO THE AFTN. SKIES SHOULD CLR OUT THIS EVE HOWEVER OVRNGT
MVFR/IFR FG IS EXPD TO DVLP.
.OUTLOOK.../THURSDAY THROUGH SUNDAY/...
VFR RTNS THU AND FRI WITH BLDG HIGH PRES. RSTRNS IN SHWRS/TSTMS ARE
PSBL SAT AND SUN AS A WRMFNT APRCHS AND MOVES THRU.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR MDZ001.
OH...NONE.
PA...FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR PAZ074-076.
WV...FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
431 PM EDT WED AUG 28 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 412 PM EDT WED AUG 28 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE OVER
THE CNTRL CONUS RESULTING IN ACYC FLOW FROM THE NRN PLAINS THROUGH
THE UPPER MS VALLEY AND GREAT LAKES. A WEAK SHORTWAVE TROUGH FROM
NEAR CYPL-CYHD INTO NW MN SUPPORTED SOME SCT SHRA/TSRA. A MORE
SIGNIFICANT UPSTREAM SHRTWV WAS MOVING FROM IDAHO INTO WRN MONTANA.
MID CLOUDS OVER MN INTO NW WI LEFTOVER FROM EARLIER CONVECTION AND A
WAA PATTERN UPSTREAM...WERE SPREADING INTO WRN UPPER MI. AT THE
SFC...A WEAK RIDGE FROM NRN ONTARIO INTO UPPER MI HAS BROUGHT MOSTLY
CLEAR SKIES AND LIGHT WINDS ACROSS UPPER MI AND PROMINENT LAKE
BREEZES. INLAND...MIXING IN THE SLIGHTLY DRIER AIRMASS PWAT AROUND
1.0 INCH (NEAR NORMAL) HAS DROPPED DEWPOINTS TO AROUND 60F.
WITH MAINLY CLEAR SKIES AND LIGHT WINDS...SOME FOG WILL DEVELOP
OVERNIGHT. HOWEVER...THERE HAS BEEN ENOUGH LOW LEVEL DRYING SO THAT
THE FOG IS NOT EXPECTED TO BECOME AS DENSE OR WIDESPREAD AS LAST
NIGHT. IN ADDITION...SOME MID CLOUDS MOVING INTO THE WEST MAY ALSO
LIMIT THE RADIATIONAL COOLING. OTHERWISE...MIN TEMPS SHOULD AGAIN
DROP TO AROUND 60 INLAND WITH LOWER TO MID 60S ALONG THE GREAT
LAKES.
AS THE NRN ROCKIES SHORTWAVE MOVES THROUGH SRN SASK AND MANITOBA TO
NRN MN WAA AHEAD OF THE SYSTEM WILL BRING INCREASING CLOUDS ACROSS
THE CWA. SOME SHRA/TSRA SUPPORTED BY 310K-315K ISENTROPIC ASCENT
NORTH OF A WARM FRONT INTO SRN MN MAY BRING SOME SHRA/TSRA FROM WRN
LAKE SUPERIOR AND NW WI INTO THE FAR WEST LATE. HOWEVER...ONLY LOW
END POPS WERE INCLUDED AS THE BULK OF ANY PCPN IS EXPECTED TO HOLD
OFF UNTIL AFT 00Z.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 431 PM EDT WED AUG 28 2013
ONE OF THE CONCERNS INHIBITING WIDESPREAD CONVECTION THURSDAY NIGHT
WILL BE THE FACT THAT THE SFC LOW/MAIN TROUGH WILL REMAIN TO OUR S.
SO WHILE THE SHORTWAVE CROSSES UPPER MI...STORMS MAY BE A BIT MORE
ELEVATED. THE LATEST NON-EURO RUNS DO INDICATE THE POTENTIAL FOR
MODERATE TO HEAVY RAIN...PRIMARILY ACROSS LAKE SUPERIOR...WITH 2-3IN
FALLING SOMEWHERE ACROSS THE CWA. EXACT TIMING AND PLACEMENT OF THE
HEAVIER RAIN WILL NEED TO BE PINNED DOWN A BIT LATER. THERE WAS
ENOUGH CERTAINTY TO KEEP LIKELY POPS GOING OVER THE FAR W LATE
THURSDAY EVENING...AND ACROSS MUCH OF THE W HALF OVERNIGHT...BEFORE
CONTINUING THE TRACK AROUND THE 500MB RIDGE AND SHIFTING TO OUR SE
FRIDAY MORNING. THE MOST UNSTABLE AIR WILL LIKELY BE ACROSS THE
INTERIOR W AND TO OUR SW...CLOSER TO THE SFC LOW.
A TEMPORARY RIDGE WILL EXPAND ACROSS THE UPPER GREAT LAKES FRIDAY
EVENING AS THE SFC LOW STRETCHING FROM N LAKE MI TO E IA EXITS
ACROSS LOWER MI. DIMINISHED THE CHANCE OF SHOWERS/TS FOR FRIDAY
NIGHT AND SATURDAY...AHEAD OF THE DEEPENING CANADIAN LOW. THE SFC
LOW IS STILL FIGURED TO BE OVER LAKE WINNIPEG AROUND 12Z
SATURDAY...AND SHIFT ACROSS S ONTARIO/LAKE SUPERIOR SUNDAY
MORNING-AFTERNOON. THE ECMWF IS REMAINS THE DEEPEST AT THE SFC AND
ALOFT WITH THIS FEATURE...BUT THE 12Z GFS IS CATCHING UP. WILL
CONTINUE TO LEAN THE FCST A BIT CLOSER TO THE ECMWF SOLUTION FOR
MUCH OF THIS PERIOD. QUICKER THAN ITS RUN FROM YESTERDAY...THE 12Z
ECMWF DEVELOPS THE 500MB LOW OVER ONTARIO SUNDAY MORNING /ABOUT
18HRS FASTER THAN THE GFS/. THIS WILL BE THE START OF OUR NEAR TO
BELOW NORMAL TEMPERATURES...AS ANOTHER LOW DIVES INTO EASTERN CANADA
ON WEDNESDAY. THE RESULT WILL BE A SIGNIFICANT TROUGH SUPPRESSING
THE STRONG HIGH TO OUR SW...AND 60S AND LOW 70S RETURNING TO THE
FCST FOR MONDAY...BEFORE MODERATING BACK TO NORMAL /70S/ BY
WEDNESDAY. STRONGER NW WINDS OF 10-20KTS ACROSS LAKE SUPERIOR AND
850MB TEMPS OF 4-6C SHOULD KEEP TEMPS IN THE 60S MONDAY...ALONG WITH
THE POTENTIAL FOR SHOWERS/DRIZZLE NEAR LAKE SUPERIOR. WAY OUT IN THE
FUTURE...THE ECMWF DOES HAVE 0 TO -2C TEMPS ACROSS LAKE SUPERIOR ON
THURSDAY. WILL WILL NEED TO WAIT AND SEE ON THAT ONE. EITHER
WAY...THE WARM AIR LOOKS TO BE DONE FOR A WHILE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 134 PM EDT WED AUG 28 2013
VFR CONDITIONS WILL PREVAIL INTO THE EVENING UNTIL FOG REDEVELOPS
WITH THE LOSS OF DAYTIME HEATING. MAINLY MVFR CONDITIONS ARE EXPECTED
AT THE THREE TAF SITES DUE TO SOME FOG FROM A FEW HOURS AFTER SUNSET
THROUGH 12Z. ALTHOUGH CONFIDENCE IN FOG INTENSITY IS LOW...THE FOG IS
NOT EXPECTED TO BECOME AS DENSE AS LAST NIGHT. HOWEVER...THERE MAY BE
SOME BRIEF PERIODS WITH VSBY DOWN TO VLIFR.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 412 PM EDT WED AUG 28 2013
PATCHY FOG WILL PERSIST THROUGH THROUGH THURSDAY AS RELATIVELY HIGH
DEWPOINTS REMAIN THROUGH THE WEEK. DRIER AIR BEGINS MOVING IN FOR
THE WEEKEND... LIMITING FOG POTENTIAL FOR THE WEEKEND. LIGHT WINDS
WILL PREVAIL THROUGH MUCH OF THE FORECAST PERIOD AS THE PRESSURE
GRADIENT REMAINS LIGHT UNDER THE INFLUENCE OF RIDGING ALOFT. THE
PRESSURE GRADIENT WILL TIGHTEN SUNDAY WITH THE PASSAGE OF A LOW
PRESSURE SYSTEM TO THE NORTH OF LAKE SUPERIOR. BEHIND THE COLD
FRONT...NORTHWEST WINDS ARE EXPECTED TO INCREASE INTO THE 15 TO 25
KNOT RANGE. WAVES WILL MAY ALSO BUILD INTO THE 3 TO 7 FOOT RANGE
WITH COLDER AIR MOVING IN.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
413 PM EDT WED AUG 28 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 412 PM EDT WED AUG 28 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE OVER
THE CNTRL CONUS RESULTING IN ACYC FLOW FROM THE NRN PLAINS THROUGH
THE UPPER MS VALLEY AND GREAT LAKES. A WEAK SHORTWAVE TROUGH FROM
NEAR CYPL-CYHD INTO NW MN SUPPORTED SOME SCT SHRA/TSRA. A MORE
SIGNIFICANT UPSTREAM SHRTWV WAS MOVING FROM IDAHO INTO WRN MONTANA.
MID CLOUDS OVER MN INTO NW WI LEFTOVER FROM EARLIER CONVECTION AND A
WAA PATTERN UPSTREAM...WERE SPREADING INTO WRN UPPER MI. AT THE
SFC...A WEAK RIDGE FROM NRN ONTARIO INTO UPPER MI HAS BROUGHT MOSTLY
CLEAR SKIES AND LIGHT WINDS ACROSS UPPER MI AND PROMINENT LAKE
BREEZES. INLAND...MIXING IN THE SLIGHTLY DRIER AIRMASS PWAT AROUND
1.0 INCH (NEAR NORMAL) HAS DROPPED DEWPOINTS TO AROUND 60F.
WITH MAINLY CLEAR SKIES AND LIGHT WINDS...SOME FOG WILL DEVELOP
OVERNIGHT. HOWEVER...THERE HAS BEEN ENOUGH LOW LEVEL DRYING SO THAT
THE FOG IS NOT EXPECTED TO BECOME AS DENSE OR WIDESPREAD AS LAST
NIGHT. IN ADDITION...SOME MID CLOUDS MOVING INTO THE WEST MAY ALSO
LIMIT THE RADIATIONAL COOLING. OTHERWISE...MIN TEMPS SHOULD AGAIN
DROP TO AROUND 60 INLAND WITH LOWER TO MID 60S ALONG THE GREAT
LAKES.
AS THE NRN ROCKIES SHORTWAVE MOVES THROUGH SRN SASK AND MANITOBA TO
NRN MN WAA AHEAD OF THE SYSTEM WILL BRING INCREASING CLOUDS ACROSS
THE CWA. SOME SHRA/TSRA SUPPORTED BY 310K-315K ISENTROPIC ASCENT
NORTH OF A WARM FRONT INTO SRN MN MAY BRING SOME SHRA/TSRA FROM WRN
LAKE SUPERIOR AND NW WI INTO THE FAR WEST LATE. HOWEVER...ONLY LOW
END POPS WERE INCLUDED AS THE BULK OF ANY PCPN IS EXPECTED TO HOLD
OFF UNTIL AFT 00Z.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 414 AM EDT WED AUG 28 2013
HIGH PRESSURE WILL BE OVER NORTHERN LAKE MICHIGAN AT THE START OF
THE PERIOD AND LEAD TO CLEAR SKIES OVER THE AREA. THE CLEAR SKIES
AND LINGERING MOIST LOW LEVELS WILL LIKELY LEAD TO SOME LINGERING
PATCHY FOG DURING THE FIRST COUPLE OF HOURS IN THE MORNING. AFTER A
CLEAR START TO THE MORNING...CLOUDS AND PRECIPITATION CHANCES WILL
BE ON THE INCREASE HEADING INTO THE AFTERNOON. THIS IS DUE TO THE
NEXT SHORTWAVE ROUNDING THE UPPER RIDGE AXIS IN THE DAKOTAS. THERE
SHOULD BE AN MCS ASSOCIATED WITH THE INITIAL SHORTWAVE EXITING NORTH
DAKOTA THURSDAY MORNING ON THE NOSE OF THE LOW LEVEL JET AND WAA.
THIS COMPLEX WILL FOLLOW THE MEAN FLOW AND INSTABILITY AXIS TO THE
EAST-SOUTHEAST AND THROUGH NORTHWEST WISCONSIN AND MAINLY JUST
BRUSHING UPPER MICHIGAN LATE THUSDAY AFTERNOON THROUGH THURSDAY
NIGHT. THE SECONDARY SHORTWAVE WILL FOLLOW A SIMILAR TRACK ALTHOUGH
A TOUCH FARTHER SOUTH FOR LATE THURSDAY NIGHT INTO FRIDAY MORNING.
WILL CONTINUE THE HIGHEST POPS ALONG THE WISCONSIN BORDER AND KEEP
AT HIGH END CHANCES AND LOW END LIKELY VALUES AT THIS POINT. SINCE
THE NAM/GEM SLIDE THE SHORTWAVE FARTHER NORTH...WILL KEEP SOME
PRECIPITATION MENTION IN THE FORECAST FOR THE REST OF UPPER MICHIGAN
ON THURSDAY NIGHT INTO FRIDAY. BASED ON THE INSTABILITY/SHEAR
VALUES...THINK THE BEST CHANCES FOR SEVERE WEATHER WILL STAY
SOUTH OF THE AREA AND MAYBE BRUSH THE SOUTHERN TIER OF COUNTIES.
LABOR DAY WEEKEND IS STILL MARKED WITH SOME DIFFERENCES IN THE
TIMING/INSTENSITY OF THE STRONG SHORTWAVE TROUGH EJECTING OUT OF
THE PACIFIC NORTHWEST ON THURSDAY NIGHT. THIS SHORTWAVE WILL ROUND
THE UPPER RIDGE ON SATURDAY (WHICH IS TRANSITIONING WEST INTO THE
ROCKIES DURING THAT TIME) AND MOVE THROUGH THE UPPER GREAT LAKES
REGION SATURDAY NIGHT THROUGH MONDAY. A SURFACE LOW ASSOCIATED WITH
THE SHORTWAVE WILL MOVE EAST ACROSS ONTARIO DURING THAT TIME FRAME
AND DRAG A COLD FRONT ACROSS UPPER MICHIGAN (MOST LIKELY SATURDAY
NIGHT). WILL HIGHLIGHT THE BEST CHANCES FOR RAIN DURING THAT
SATURDAY NIGHT PERIOD...BUT INCLUDE SLIGHT CHANCES BEFORE/AFTER DUE
TO THE TIMING DIFFERENCES. THIS COLD FRONT WILL BRING MUCH COOLER
TEMPERATURES TO THE AREA FOR SUNDAY AND MONDAY. THERE MAY BE ENOUGH
WARM AIR AROUND ON SUNDAY TO KEEP HIGHS AROUND NORMAL...BUT MONDAY
LOOKS TO BE BELOW NORMAL AS 850MB TEMPS FALL TO AROUND 6C. HIGH
PRESSURE WILL BUILD OVER THE AREA FOR MONDAY INTO TUESDAY AND LEAD
TO DRY WEATHER...ALTHOUGH THERE MAY BE SOME UPSLOPE DRIZZLE EARLY ON
MONDAY IN THE FAVORED AREAS NEAR LAKE SUPERIOR. EXPECT CLOUDS TO BE
OVER THE AREA FOR MONDAY UNDER THE NORTH-NORTHWESTERLY FLOW BUT THEY
SHOULD PULL OUT MONDAY NIGHT. WITH THE UPPER RIDGE BUILDING BUILDING
BACK TO THE EAST...EXPECT TEMPERATURES TO BEGIN WARMING CLOSER TO
NORMAL FOR TUESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 134 PM EDT WED AUG 28 2013
VFR CONDITIONS WILL PREVAIL INTO THE EVENING UNTIL FOG REDEVELOPS
WITH THE LOSS OF DAYTIME HEATING. MAINLY MVFR CONDITIONS ARE EXPECTED
AT THE THREE TAF SITES DUE TO SOME FOG FROM A FEW HOURS AFTER SUNSET
THROUGH 12Z. ALTHOUGH CONFIDENCE IN FOG INTENSITY IS LOW...THE FOG IS
NOT EXPECTED TO BECOME AS DENSE AS LAST NIGHT. HOWEVER...THERE MAY BE
SOME BRIEF PERIODS WITH VSBY DOWN TO VLIFR.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 412 PM EDT WED AUG 28 2013
PATCHY FOG WILL PERSIST THROUGH THROUGH THURSDAY AS RELATIVELY HIGH
DEWPOINTS REMAIN THROUGH THE WEEK. DRIER AIR BEGINS MOVING IN FOR
THE WEEKEND... LIMITING FOG POTENTIAL FOR THE WEEKEND. LIGHT WINDS
WILL PREVAIL THROUGH MUCH OF THE FORECAST PERIOD AS THE PRESSURE
GRADIENT REMAINS LIGHT UNDER THE INFLUENCE OF RIDGING ALOFT. THE
PRESSURE GRADIENT WILL TIGHTEN SUNDAY WITH THE PASSAGE OF A LOW
PRESSURE SYSTEM TO THE NORTH OF LAKE SUPERIOR. BEHIND THE COLD
FRONT...NORTHWEST WINDS ARE EXPECTED TO INCREASE INTO THE 15 TO 25
KNOT RANGE. WAVES WILL MAY ALSO BUILD INTO THE 3 TO 7 FOOT RANGE
WITH COLDER AIR MOVING IN.
&&
.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 MARQUETTE MI
415 AM EDT WED AUG 28 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 428 PM EDT TUE AUG 27 2013
WV IMAGERY AND RUC ANALYSIS INDICATED WNW FLOW THROUGH THE NRN GREAT
LAKES ATOP A MID/UPPER LEVEL RIDGE CENTERED OVER MO/KS/AR. NO
SHORTWAVE TROUGHS WERE NOTED UPSTREAM THAT ARE LIKELY TO HAVE A
SIGNIFICANT AFFECT ON UPPER MICHIGAN. AT THE SFC...A WEAK
TROUGH/FRONT EXTENDED FROM NEAR MNM TO MSP WITH WEAK HIGH PRES TO
THE NW OF LAKE SUPERIOR BRINGING LIGHT NE LOW LEVEL FLOW ACROSS LAKE
SUPERIOR. PERSISTENT LOW CLOUDS OVER THE SRN HLF OF THE CWA...HAVE LIMITED
TEMPS AND RESULTANT INSTABILITY DESPITE DEWPOINTS REMAINING AROUND
70. THE LAKE BREEZE FRONT INTO NRN UPPER MI HAS PRODUCED MAINLY JUST
TCU WITH ONLY A FEW SPRINKLES. WHILE THE TSRA ALONG THE 900-700 MB
FGEN ZONE THROUGH S CNTRL UPPER MI HAD MOVED INTO NRN LAKE
MI...ADDITIONAL TSRA WERE DEVELOPING IN NE WI JUST TO THE NORTH OF
THE FRONT WHERE MLCAPE VALUES HAD CLIMBED INTO THE 2K-3K J/KG RANGE.
EXPECT MAINLY JUST ISOLD SHRA AND POSSIBLY A TSRA OVER CNTRL UPPER
MI ALONG THE LAKE BREEZE BOUNDARY LATE THIS AFTERNOON AND EVENING
WHERE INSTABILITY WAS MORE MODEST...ONLY TO NEAR 500-1000 J/KG. THE
STRONGER TSRA ALONG THE FRONT MAY JUST BRUSH THE FAR SRN CWA NEAR
MNM EARLY BUT SHOULD SAG SOUTH OF THE AREA BY 21Z-22Z. ADDITIONAL
ELEVATED SHRA/TSRA NEAR ESC LATE THIS AFTERNOON IN THE AREA OF
WAA/ISENTROPIC LIFT SHOULD ALSO MOVE OFF TO THE SE BY THIS EVENING.
LARGER SCALE SUBSIDENCE WILL THEN TAKE OVER TONIGHT AS WEAK TO
MODERATE 700-300 MB QVECTOR DIV AND SFC HIGH PRES BUILDS OVER THE
AREA. WITH THE LIGHT WINDS AND ABUNDANT LOW LEVEL MOISTURE...AREAS
OF FOG/STRATUS ARE EXPECTED TO DEVELOP. WITH ONLY WEAK DRY ADVECTION
AND DEWPOINTS ONLY DROPPING INTO THE LOWER TO MID 60S...MIN TEMPS
WILL REMAIN WELL ABOVE NORMAL. THE NNE LOW LEVEL FLOW TONIGHT INTO
EARLY WED COULD ALSO BRING FOG/STRATUS INTO LOCATIONS ALONG LAKE
SUPERIOR. AFTER DAYTIME HEATING BURNS OFF ANY LINGERING LOW
CLOUDS...SUNSHINE SHOULD PUSH INLAND TEMPS INTO THE LOWER TO MID 80S
WITH LOWER READINGS IN THE MID TO UPPER 70S ALONG LAKE SUPERIOR.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 414 AM EDT WED AUG 28 2013
HIGH PRESSURE WILL BE OVER NORTHERN LAKE MICHIGAN AT THE START OF
THE PERIOD AND LEAD TO CLEAR SKIES OVER THE AREA. THE CLEAR SKIES
AND LINGERING MOIST LOW LEVELS WILL LIKELY LEAD TO SOME LINGERING
PATCHY FOG DURING THE FIRST COUPLE OF HOURS IN THE MORNING. AFTER A
CLEAR START TO THE MORNING...CLOUDS AND PRECIPITATION CHANCES WILL
BE ON THE INCREASE HEADING INTO THE AFTERNOON. THIS IS DUE TO THE
NEXT SHORTWAVE ROUNDING THE UPPER RIDGE AXIS IN THE DAKOTAS. THERE
SHOULD BE AN MCS ASSOCIATED WITH THE INITIAL SHORTWAVE EXITING NORTH
DAKOTA THURSDAY MORNING ON THE NOSE OF THE LOW LEVEL JET AND WAA.
THIS COMPLEX WILL FOLLOW THE MEAN FLOW AND INSTABILITY AXIS TO THE
EAST-SOUTHEAST AND THROUGH NORTHWEST WISCONSIN AND MAINLY JUST
BRUSHING UPPER MICHIGAN LATE THUSDAY AFTERNOON THROUGH THURSDAY
NIGHT. THE SECONDARY SHORTWAVE WILL FOLLOW A SIMILAR TRACK ALTHOUGH
A TOUCH FARTHER SOUTH FOR LATE THURSDAY NIGHT INTO FRIDAY MORNING.
WILL CONTINUE THE HIGHEST POPS ALONG THE WISCONSIN BORDER AND KEEP
AT HIGH END CHANCES AND LOW END LIKELY VALUES AT THIS POINT. SINCE
THE NAM/GEM SLIDE THE SHORTWAVE FARTHER NORTH...WILL KEEP SOME
PRECIPITATION MENTION IN THE FORECAST FOR THE REST OF UPPER MICHIGAN
ON THURSDAY NIGHT INTO FRIDAY. BASED ON THE INSTABILITY/SHEAR
VALUES...THINK THE BEST CHANCES FOR SEVERE WEATHER WILL STAY
SOUTH OF THE AREA AND MAYBE BRUSH THE SOUTHERN TIER OF COUNTIES.
LABOR DAY WEEKEND IS STILL MARKED WITH SOME DIFFERENCES IN THE
TIMING/INSTENSITY OF THE STRONG SHORTWAVE TROUGH EJECTING OUT OF
THE PACIFIC NORTHWEST ON THURSDAY NIGHT. THIS SHORTWAVE WILL ROUND
THE UPPER RIDGE ON SATURDAY (WHICH IS TRANSITIONING WEST INTO THE
ROCKIES DURING THAT TIME) AND MOVE THROUGH THE UPPER GREAT LAKES
REGION SATURDAY NIGHT THROUGH MONDAY. A SURFACE LOW ASSOCIATED WITH
THE SHORTWAVE WILL MOVE EAST ACROSS ONTARIO DURING THAT TIME FRAME
AND DRAG A COLD FRONT ACROSS UPPER MICHIGAN (MOST LIKELY SATURDAY
NIGHT). WILL HIGHLIGHT THE BEST CHANCES FOR RAIN DURING THAT
SATURDAY NIGHT PERIOD...BUT INCLUDE SLIGHT CHANCES BEFORE/AFTER DUE
TO THE TIMING DIFFERENCES. THIS COLD FRONT WILL BRING MUCH COOLER
TEMPERATURES TO THE AREA FOR SUNDAY AND MONDAY. THERE MAY BE ENOUGH
WARM AIR AROUND ON SUNDAY TO KEEP HIGHS AROUND NORMAL...BUT MONDAY
LOOKS TO BE BELOW NORMAL AS 850MB TEMPS FALL TO AROUND 6C. HIGH
PRESSURE WILL BUILD OVER THE AREA FOR MONDAY INTO TUESDAY AND LEAD
TO DRY WEATHER...ALTHOUGH THERE MAY BE SOME UPSLOPE DRIZZLE EARLY ON
MONDAY IN THE FAVORED AREAS NEAR LAKE SUPERIOR. EXPECT CLOUDS TO BE
OVER THE AREA FOR MONDAY UNDER THE NORTH-NORTHWESTERLY FLOW BUT THEY
SHOULD PULL OUT MONDAY NIGHT. WITH THE UPPER RIDGE BUILDING BUILDING
BACK TO THE EAST...EXPECT TEMPERATURES TO BEGIN WARMING CLOSER TO
NORMAL FOR TUESDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 133 AM EDT WED AUG 28 2013
WITH A WARM AND HUMID AIRMASS IN PLACE TONIGHT...EXPECT VLIFR
CONDITIONS AT ALL SITES WITH FOG CAUSED BY SOME UPSLOPE FLOW. MIXING
AND HEATING WILL DISSIPATE THE FOG EARLY WED MORNING AND CONDITIONS
AT ALL SITES WILL RAPIDLY GO BACK TO VFR THROUGH THE REST OF THE
FORECAST PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 428 PM EDT TUE AUG 27 2013
LIMITED PRESSURE GRADIENTS ACROSS LAKE SUPERIOR SHOULD KEEP WINDS
BELOW 20KTS THROUGH THE FORECAST PERIOD. AREAS OF FOG WILL PERSIST
ACROSS MUCH OF LAKE SUPERIOR WITH HIGH DEWPOINTS OVER THE REGION.
AS WINDS TURN TO THE NORTH TONIGHT...EXPECT THE FOG TO PUSH SOUTH
THROUGH WEDNESDAY MORNING AND THEN DIMINISH SOME AS SLIGHTLY DRIER
CANADIAN AIR MOVES SOUTH OVER THE LAKE THROUGH WEDNESDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
DENSE FOG ADVISORY UNTIL 11 AM EDT /10 AM CDT/ THIS MORNING FOR
LSZ240-245>249-265.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
134 AM EDT WED AUG 28 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 428 PM EDT TUE AUG 27 2013
WV IMAGERY AND RUC ANALYSIS INDICATED WNW FLOW THROUGH THE NRN GREAT
LAKES ATOP A MID/UPPER LEVEL RIDGE CENTERED OVER MO/KS/AR. NO
SHORTWAVE TROUGHS WERE NOTED UPSTREAM THAT ARE LIKELY TO HAVE A
SIGNIFICANT AFFECT ON UPPER MICHIGAN. AT THE SFC...A WEAK
TROUGH/FRONT EXTENDED FROM NEAR MNM TO MSP WITH WEAK HIGH PRES TO
THE NW OF LAKE SUPERIOR BRINGING LIGHT NE LOW LEVEL FLOW ACROSS LAKE
SUPERIOR. PERSISTENT LOW CLOUDS OVER THE SRN HLF OF THE CWA...HAVE LIMITED
TEMPS AND RESULTANT INSTABILITY DESPITE DEWPOINTS REMAINING AROUND
70. THE LAKE BREEZE FRONT INTO NRN UPPER MI HAS PRODUCED MAINLY JUST
TCU WITH ONLY A FEW SPRINKLES. WHILE THE TSRA ALONG THE 900-700 MB
FGEN ZONE THROUGH S CNTRL UPPER MI HAD MOVED INTO NRN LAKE
MI...ADDITIONAL TSRA WERE DEVELOPING IN NE WI JUST TO THE NORTH OF
THE FRONT WHERE MLCAPE VALUES HAD CLIMBED INTO THE 2K-3K J/KG RANGE.
EXPECT MAINLY JUST ISOLD SHRA AND POSSIBLY A TSRA OVER CNTRL UPPER
MI ALONG THE LAKE BREEZE BOUNDARY LATE THIS AFTERNOON AND EVENING
WHERE INSTABILITY WAS MORE MODEST...ONLY TO NEAR 500-1000 J/KG. THE
STRONGER TSRA ALONG THE FRONT MAY JUST BRUSH THE FAR SRN CWA NEAR
MNM EARLY BUT SHOULD SAG SOUTH OF THE AREA BY 21Z-22Z. ADDITIONAL
ELEVATED SHRA/TSRA NEAR ESC LATE THIS AFTERNOON IN THE AREA OF
WAA/ISENTROPIC LIFT SHOULD ALSO MOVE OFF TO THE SE BY THIS EVENING.
LARGER SCALE SUBSIDENCE WILL THEN TAKE OVER TONIGHT AS WEAK TO
MODERATE 700-300 MB QVECTOR DIV AND SFC HIGH PRES BUILDS OVER THE
AREA. WITH THE LIGHT WINDS AND ABUNDANT LOW LEVEL MOISTURE...AREAS
OF FOG/STRATUS ARE EXPECTED TO DEVELOP. WITH ONLY WEAK DRY ADVECTION
AND DEWPOINTS ONLY DROPPING INTO THE LOWER TO MID 60S...MIN TEMPS
WILL REMAIN WELL ABOVE NORMAL. THE NNE LOW LEVEL FLOW TONIGHT INTO
EARLY WED COULD ALSO BRING FOG/STRATUS INTO LOCATIONS ALONG LAKE
SUPERIOR. AFTER DAYTIME HEATING BURNS OFF ANY LINGERING LOW
CLOUDS...SUNSHINE SHOULD PUSH INLAND TEMPS INTO THE LOWER TO MID 80S
WITH LOWER READINGS IN THE MID TO UPPER 70S ALONG LAKE SUPERIOR.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 428 PM EDT TUE AUG 27 2013
SFC HIGH OVERHEAD WEDNESDAY NIGHT SLOWLY SINKING SE THROUGH
FRIDAY...AS A WEAK FRONTAL TROUGH LINGERS ACROSS CENTRAL AND S
ONTARIO. WEDNESDAY NIGHT INTO THURSDAY MORNING STILL LOOK DRY...OUT
AHEAD OF THE NEXT SHORTWAVE OVER S ONTARIO ROUNDING THE SIGNIFICANT
RIDGE DOMINATING MUCH OF THE CENTRAL U.S. IT STILL LOOKS LIKE THE
BEST CHANCE FOR CONVECTION AND MODERATE RAIN WILL BE ALONG AND S OF
THE WI BORDER THURSDAY NIGHT.
LARGE HIGH PRESSURE OVER CENTRAL CANADA WILL SHIFT ACROSS N
ONTARIO ON FRIDAY...LEAVING UPPER MI IN BETWEEN -2 TO -6C AIR OVER S
HUDSON BAY HOTTER 22-25C TEMPERATURES OVER THE CENTRAL PLAINS. WITH
A SERIES OF WEAKER DISTURBANCES SWINGING IN FROM THE NW IT WILL BE
DIFFICULT TO KEEP THE MENTION OF SHOWERS AND THUNDERSTORMS OUT OF
THE FCST FOR FRIDAY AND FRIDAY NIGHT...ALTHOUGH THE LATEST MODEL
GUIDANCE DOES SUGGEST THAT IT COULD BE TRIMMED BACK A BIT MORE THAN
MY LAST MINUTE 20Z UPDATE.
THE SFC LOW CENTERED OVER THE PLAINS WILL SINK TO OUR S ON SATURDAY.
THIS WILL RESTRICT MUCH OF THE HOTTER AIR FROM PUSH ACROSS THE UPPER
GREAT LAKES. THE MAIN STORY WILL BE THE DEEPENING SFC LOW OVER LAKE
WINNIPEG FRIDAY NIGHT/SATURDAY MORNING MOVING ACROSS CENTRAL AND S
ONTARIO SATURDAY NIGHT /BOTTOMING OUT PRESSURE WISE AROUND 997MB/.
THE COLD FRONT IS EXPECTED TO DRAG ACROSS W AND CENTRAL UPPER MI
OVERNIGHT...AND EXIT E UPPER MI SUNDAY MORNING.
THE 27/00Z ECMWF LOOKS TO BE QUICKER AND DEEPER STILL WITH THE
TIMING OF THE 500MB TROUGH SWINGING ACROSS S CENTRAL CANADA AND
SUPPRESSING THE DOMINANT RIDGE TO THE 4-CORNERS REGION...AND IS A
SIGNIFICANT OUTLIER COMPARED TO THE GFS ENSEMBLE MEMBERS. WITH THE
TROUGH FORMING A FULL-FLEDGED LOW OVER SE CANADA MONDAY/MONDAY
NIGHT...UPPER MI WILL BE ABLE TO GET SOME RELIEF FROM THE HEAT.
SINGLE DIGIT 850MB TEMPS WILL SLIDE IN SUNDAY NIGHT...WITH BOTH 12Z
RUNS OF THE ECMWF AND GFS SHOWING 4C MONDAY MORNING.
THE COOLER TEMPERATURES WILL BE SHORT LIVED AS THE HIGH AMPLITUDE
500MB RIDGE OVER THE SOUTHERN STATES EXTENDS ACROSS THE ROCKIES ON
MONDAY...AND PUSHES ACROSS THE N PLAINS/S CENTRAL CANADA AND EDGES
ACROSS THE UPPER GREAT LAKES ON TUESDAY. LOOK FOR 70S AND POSSIBLY
80S TO RETURN AGAIN BY THE MIDDLE OF NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 133 AM EDT WED AUG 28 2013
WITH A WARM AND HUMID AIRMASS IN PLACE TONIGHT...EXPECT VLIFR
CONDITIONS AT ALL SITES WITH FOG CAUSED BY SOME UPSLOPE FLOW. MIXING
AND HEATING WILL DISSIPATE THE FOG EARLY WED MORNING AND CONDITIONS
AT ALL SITES WILL RAPIDLY GO BACK TO VFR THROUGH THE REST OF THE
FORECAST PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 428 PM EDT TUE AUG 27 2013
LIMITED PRESSURE GRADIENTS ACROSS LAKE SUPERIOR SHOULD KEEP WINDS
BELOW 20KTS THROUGH THE FORECAST PERIOD. AREAS OF FOG WILL PERSIST
ACROSS MUCH OF LAKE SUPERIOR WITH HIGH DEWPOINTS OVER THE REGION.
AS WINDS TURN TO THE NORTH TONIGHT...EXPECT THE FOG TO PUSH SOUTH
THROUGH WEDNESDAY MORNING AND THEN DIMINISH SOME AS SLIGHTLY DRIER
CANADIAN AIR MOVES SOUTH OVER THE LAKE THROUGH WEDNESDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
DENSE FOG ADVISORY UNTIL 11 AM EDT /10 AM CDT/ THIS MORNING FOR
LSZ240-245>249-265.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION
NWS DULUTH MN
649 PM CDT THU AUG 29 2013
.AVIATION...
STORMS IN VICINITY OF SEVERAL TAFS AT THIS TIME...AND MOVING
SWIFTLY EAST IN ADVANCE OF A COLD FRONT. STORMS ARE BRINGING IFR
CONDITIONS. FRONT TO MOVE THROUGH LATER THIS EVENING AND LATE
TONIGHT...ENDING THUNDER THREAT. BEHIND COLD FRONT EXPECT AN AREA
OF STRATUS AND FOG TO FORM...BRINGING AT LEAST MVFR
CONDITIONS...THOUGH SOME SITES MAY GET IFR CONDITIONS. NORTHWEST
WINDS OF 10-15KTS TO KEEP VISIBILITIES FROM GETTING VERY LOW. STRATUS
SHOULD LINGER THROUGH EARLY FRIDAY MORNING. FRIDAY MORNING
CONDITIONS TO RETURN TO VFR CONDITIONS...AND REMAIN THAT WAY THE
REMAINDER OF FRIDAY.
&&
.PREV DISCUSSION... /ISSUED 350 PM CDT THU AUG 29 2013/
SHORT TERM...THE MAIN FOCUS FOR TONIGHT IS THUNDERSTORMS.
AT 330 PM...THUNDERSTORMS WERE GENERALLY ON THE DECREASE ACROSS
THE CWA. THE STRONGEST STORM WAS LOCATED OVER IRON COUNTY. THIS
WAS PART OF THE LARGE LINE OF STORMS THAT MOVED FROM THE DAKOTAS
LAST NIGHT...THROUGH NORTHERN MINNESOTA AND NORTHERN WISCONSIN.
TEMPERATURES RANGED FROM THE 60S NEAR LAKE SUPERIOR TO NEAR 90 IN
OUR FAR SOUTHERN COUNTIES. DEWPOINTS WERE LARGELY IN THE 60S NORTH
TO THE 70S SOUTH.
THE MAIN FOCUS FOR TONIGHT WILL DEFINITELY BE THUNDERSTORMS. THE
ATMOSPHERE HAS BEEN WORKED OVER PRETTY WELL FROM THE MCS THAT
MOVED ACROSS MUCH OF THE CWA DURING THE DAY. IT MAY STILL TAKE
SOME TIME BEFORE THINGS DESTABILIZE FURTHER FOR MORE DEVELOPMENT
LATER THIS AFTERNOON AND INTO THE EVENING. THE NMM WRF/NSSL WRF/
HRRR AND RAP NOT DOING THE BEST AS OF 330 PM. THE 4 KM NMM WRF
SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT SCENARIO. THIS MODEL
INDICATES THAT STORMS WILL FIRE UP AGAIN ACROSS NW MN AND SWEEP
FROM NW TO SE ACROSS ESPECIALLY THE SW 1/3 OF THE CWA. THIS WOULD
MAKE THE MOST SENSE AS THIS SHOULD BE THE AREA MOST APT TO
DESTABILIZE AND WITH THE BEST SURFACE CONVERGENCE. MANY OF THE
MODELS ARE ACTUALLY INDICATING THE MOST WIDESPREAD PRECIPITATION
ACROSS NORTHERN PORTIONS OF THE AREA...WHICH WOULD BE WHERE IT HAS
LARGELY STABILIZED THOUGH.
FRIDAY SHOULD BE MUCH MORE QUIET...AS A COLD FRONT BRINGS A BIT
COOLER AND DRIER AIR TO THE REGION. HIGH TEMPERATURES SHOULD STILL
BE IN THE 80S FOR THE MOST PART.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
DRY CONDITIONS ARE EXPECTED FRI NIGHT AND EARLY SAT ACROSS MUCH OF
THE UPPER MIDWEST AS A WEAK RIDGE OF HIGH PRESSURE ALOFT AND A SFC
HIGH DOMINATE THE REGION. THE NEXT SYSTEM WILL DEVELOP OVER THE NRN
PLAINS AND CANADIAN FRONT RANGE FRI NIGHT AND MOVE EWD THROUGH NRN
MN AND INTO WRN ONTARIO DURING THE DAY SAT AND SAT NIGHT. THE MODELS
ARE IN VERY GOOD AGREEMENT BRINGING THE SFC LOW EWD JUST NORTH OF
THE INTERNATIONAL BORDER INTO WRN ONTARIO BY SUNDAY MORNING...WITH A
SFC TROUGH/COLD FRONT EXTENDING SWD THROUGH MN. SHOWERS AND STORMS
ARE EXPECTED TO SPREAD ACROSS THE REGION ALONG AND AHEAD OF THIS
FRONT...WITH A CHANCE OF A FEW STRONG OR SEVERE STORMS. AS THE SFC
LOW TRACKS TO THE EAST INTO CENTRAL ONTARIO AND THE FRONT SLIDES
INTO WI/MICH U.P. A TIGHT PRES GRADIENT WILL SET UP ON THE BACK SIDE
OF THE LOW IN NE MN AND ALLOW GUSTY N WINDS TO DEVELOP WITH A FEW
SUNDAY MORNING AND AFTERNOON CAA RAIN SHOWERS. HIGH PRESSURE WILL
MOVE IN AND DOMINATE THE AREA BY MONDAY AND CONTINUE TO BRING DRY
CONDITIONS TO THE NORTHLAND THROUGH TUE AND INTO EARLY WED. A WEAK
FRONT WILL DROP SWD INTO THE REGION LATE WED AND BRING WITH IT
ADDITIONAL CHANCES FOR SHOWERS.
TEMPERATURES SATURDAY WILL CONTINUE TO BE WARM WITH HIGHS IN THE
UPPER 70S AND LOWER TO MID 80S...ALONG WITH HUMID CONDITIONS.
HOWEVER...THE COLD FRONT ON SATURDAY NIGHT WILL USHER IN A MUCH
DRIER AND COOLER AIR MASS WITH HIGHS ON SUN AND MON IN THE 60S AND
70S...AND NOTICEABLY LOWER HUMIDITIES. TEMPS WARM BA
AVIATION...18Z TAF ISSUANCE...
LINE OF THUNDERSTORMS CURRENTLY MOVING TO THE EAST JUST NORTH OF
DLH WITH GUSTY WINDS...HEAVY LINE AND FREQUENT LIGHTNING. A BRIEF
BREAK IN THE CONVECTION IS EXPECTED EARLY THIS AFTERNOON BEFORE
ANOTHER ROUND DEVELOPS IN THE LATE AFTERNOON ACROSS N-CENTRAL MN
AND MOVES ACROSS THE NORTHLAND EARLY THIS EVENING. SOME OF THE
STORMS COULD BECOME STRONG TO SEVERE WITH VERY GUSTY WINDS AND
HAIL. A FEW OF THE STORMS COULD LINGER AROUND HYR UNTIL
06-08Z...OTHERWISE CONDITIONS CLEAR OUT FROM WEST TO EAST INTO
EARLY FRIDAY MORNING. WINDS WILL INCREASE FROM THE NNW DURING THE
MORNING FRIDAY...WITH MVFR CIGS.
&&
.POINT TEMPS/POPS...
DLH 64 80 58 79 / 80 30 0 20
INL 61 84 62 82 / 50 10 20 50
BRD 68 86 62 86 / 60 10 0 40
HYR 71 83 58 84 / 70 30 0 10
ASX 68 78 59 78 / 80 30 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
AVIATION...LE
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
936 PM CDT Thu Aug 29 2013
.UPDATE:
Issued at 930 PM CDT Thu Aug 29 2013
Mid-evening update mainly to remove isolated thunderstorms from
the forecast over south central Illinois. The rest of the forecast
looks to be in good shape for the rest of the night. Noticed that
the RUC is spitting out some precip over parts of west central and
central Missouri late tonight in proximity to the upper low now
moving through eastern Kansas in an area of weak 850mb warm
advection. The new 00Z NAM is dry until after sunrise and then the
precip is further to the southwest. Will keep the forecast dry for
the rest of the night and let the midnight shift add in some
isolated showers or storms if something does indeed pop up.
Carney
&&
.SHORT TERM: (Through Late Tonight)
Issued at 254 PM CDT Thu Aug 29 2013
The front at midday was located from extreme southeast IA to east of
a KUIN-KSLO line into western KY, while a weak north-south surface
ridge axis was located through central MO. The front appears to be
trying to jump west into a new wind shift line closer to the MS
River. However, the more agitated cu field and axis of greatest
instability and weak CIN resides along the more eastern location,
and present indications are this would be the most favored location
for isolated shower/thunderstorm development through early evening.
After sunset the threat of any precipitation appears quite low as
the air mass will become more stable, diurnal cu will dissipate, and
any forcing along the boundary will be quite weak. Otherwise,
tonight looks rather uneventful with the upper low dropping
southeastward through KS spreading some high clouds into the western
half of the CWA, and min temperatures a tad bit warmer.
Glass
.LONG TERM: (Friday through Next Thursday)
Issued at 254 PM CDT Thu Aug 29 2013
Upper level shortwave over southwestern Missouri will continue to
slowly slide to the south on Friday. Could see a slight chance of
showers and thunderstorms mainly over the Ozarks on Friday. In the
meantime the next frontal boundary, currently over South
Dakota/western Nebraska, will move into northern Missouri by Friday
afternoon. Activity associated with this boundary, very scattered in
nature, will move into northeast MO, west central IL Friday evening.
There could be some lingering isolated activity associated with
upper level system over southern and eastern portions of forecast
area as well.
As for high temperatures on Friday, it will be a bit warmer than
today, but with a few more clouds and dewpts still mixing out, heat
indicies will remain in the 100 to 104 range, though a few spots
could reach 105.
By Saturday, cold front to weaken even more as it slides through
region. There is a chance of a few storms, mainly over far eastern
portions of forecast area. Otherwise, another hot day in store
despite a few more clouds and front moving through. Highs will be in
the low to mid 90s with heat indicies between 100 and 104.
A more vigorous cold front to approach area late Saturday night with
best chances of rain Sunday and Sunday night. Again not a lot of
moisture associated with it, so activity to be rather scattered with
it. With this front, cooler and less humid air to make its way into
region, so will keep heat advisory headline going through Saturday
for metro area, no need to extend it beyond this time period.
Beyond that, precipitation to taper off very early Monday morning
with surface ridge building in and more seasonable temperatures
expected through the work week.
Byrd
&&
.AVIATION: (For the 00z TAFs through 00z Friday Evening)
Issued at 630 PM CDT Thu Aug 29 2013
Remnants of cold front/surface trof has migrated westward and
lies roughly along the Mississippi River at 23z, but it certainly
appears that its westward propagation is over. Late afternoon
convection that developed over southern Illinois...in the best instability
axis but east of the surface convergence...appears to have
already peaked and is in the process of dissipating as it remains
well removed from any TAF sites.
It appears that stationary surface trof/wind shift will wash out
overnight as surface ridge works east across lower
Michigan...with pressure falls allowing a weak southerly flow to
develop on the east side of the boundary as the night progresses.
Threat of convection with this feature appears to be extremely
low as we lose any residual effects of daytime heating. Will need
to keep an eye on some fog threat (MVFR vsbys) developing late
tonight...but attm it would appear that subtle increase in mixing
may keep this at bay.
Winds should develop a fairly pronounced westerly component on
Friday as cold front begins dropping south from IA. It appears
that conditions in the warm sector and all TAF sites will be
similar to those of the past few days, with a bit of scattered cu.
Any convection threat with the cold front should mainly be after
this TAF period.
Specifics for KSTL: VFR conditions will persist tonight, and once
cu dissipates only a few clouds aoa 10kft are expected. With the
surface trof stalling over the area this evening winds should be
light and variable early on, then take on a southerly component
during the predawn hours as the trof washes out. On Friday looking
for another late morning and afternoon of fair weather cu, with
winds becoming westerly in the 7-10kt range.
Truett
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...HEAT ADVISORY until 7 PM CDT Saturday FOR St. Charles MO-St.
Louis City MO-St. Louis MO.
IL...HEAT ADVISORY until 7 PM CDT Saturday FOR Madison IL-St. Clair
IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
255 PM MDT WED AUG 28 2013
.DISCUSSION...
A DEEP SUBTROPICAL MOISTURE SURGE HAS ARRIVED OVER SOUTHERN NM AS A
WELL DEFINED INVERTED TROUGH SHIFTS SLOWLY NORTHWEST OF THE AREA.
CIRA BLENDED TOTAL PWAT VALUES ARE 150-175PCT OF NORMAL OVER THE
EL PASO AREA...AND THIS MOISTURE WILL ADVECT NORTH THRU TONIGHT ON
INCREASING 700-500MB SSE FLOW. ABUNDANT CLOUD COVER HAS LIMITED
CONVECTION ACROSS MUCH OF THE SOUTH THUS FAR HOWEVER A SLUG OF
NMRS SHRA/TSRA DEVELOPING AROUND I-10 AND IS SLIDING NORTH. LATEST
RUC AND HRRR SHOW THIS MASS OF PRECIP MOVING NORTH UP THE RGV AND
SOUTHERN HIGH TERRAIN INTO THIS EVENING BEFORE TAPERING OFF AFTER
MIDNIGHT. HAVE TIGHTENED UP POPS FURTHER WITH FOCUS OVER CATRON...
SOCORRO...AND LINCOLN COUNTIES.
CLOUD COVER ASSCD WITH THIS AREA OF PRECIP WILL LINGER INTO EARLY
THURSDAY AND LIKELY LIMIT CONVECTION AGAIN UNTIL LATE DAY WITHIN
ITS PERIPHERY. MODELS DO SHOW A SIMILAR FEATURE TMRW BUT FARTHER
NORTH WITH A MASS OF SHRA/TSRA SLIDING ACROSS THE SW HIGH TERRAIN
AND SOUTHERN PORTIONS OF THE NM CONT DVD THRU MID DAY. CONVECTION
SHOULD BE MORE WIDESPREAD FOR THE REMAINDER OF THE HIGH TERRAIN
AFT 3 OR 4 PM AS THETA-E RIDGE VALUES ARE HIGHER AND LIFTED INDICES
MORE UNSTABLE.
THE REAL JUICE AND FORCING MOVES INTO THE REGION FRIDAY THRU MONDAY
WITH PWAT VALUES AVERAGING AROUND 1.2 INCHES. FOCUS FOR CONVECTION
WILL BE OVER NORTHERN AND WESTERN NM FRIDAY...THEN OVER CENTRAL
AND NORTHERN NM FOR SATURDAY THROUGH MONDAY AS A BACK DOOR FRONTAL
BNDRY MOVES SW OVER THE AREA. LCL HEAVY RAIN THREAT WILL INCREASE
AND FLASH FLOOD WATCHES ARE POSSIBLE FOR AT LEAST BURN SCAR AREAS
THRU THE LABOR DAY HOLIDAY. FOLKS PLANNING OUTDOOR ACTIVITIES OVER
THE HOLIDAY WEEKEND SHOULD PREPARE FOR WET WEATHER. TEMPS IN THIS
PATTERN WILL BE CLOSER TO SEASONAL NORMALS.
GUYER
&&
.FIRE WEATHER...
BASED ON SATELLITE IMAGERY...ABUNDANT MOISTURE IS TRYING TO FLOW UP
FROM MEXICO. SOUTHERN PORTIONS OF THE AREA...ESPECIALLY SOCORRO
COUNTY WESTWARD WILL EXPERIENCE WETTING RAIN TODAY AND TONIGHT.
ISOLATED WETTING RAIN WILL BE FOUND FURTHER NORTH OVER THE NORTHWEST
AND NORTH CENTRAL MOUNTAINS. THE MID LEVEL DRY INTRUSION WHICH WAS
SQUARELY OVER THE FORECAST AREA YESTERDAY HAS SHIFTED
NORTH/NORTHEAST...THUS THE LOWEST HUMIDITY VALUES ARE FOUND THERE.
OVERALL...HUMIDITY VALUES HAVE TRENDED UP TODAY.
MOISTURE WILL CONTINUE TO MOVE NORTH AND WESTWARD ON THURSDAY. THIS
WILL SET THE STAGE FOR INCREASE WETTING RAIN COVERAGE CENTRAL
MOUNTAINS WESTWARD DURING THE AFTERNOON AND EVENING. A PRETTY DECENT
WETTING RAIN SIGNAL SHOWS UP ACROSS THE NORTHWEST AND WEST CENTRAL
HIGHLANDS. DRIER AND MORE STABLE AIR WILL BE FOUND OVER THE EASTERN
PLAINS. HUMIDITY VALUES FOR THE MOST PART WILL TREND UP EVEN MORE
ALTHOUGH LOWER SLIGHTLY ACROSS THE FAR EAST. HIGH TEMPERATURES WILL
BE ABOVE NORMAL NORTH AND EAST AS THE HIGH CENTER SHIFTS MORE OVER
PORTIONS OF THE SOUTHERN ROCKIES AND PLAINS INCLUDING OVER PARTS OF
NEW MEXICO. DUE TO THE PROXIMITY OF THE HIGH PRESSURE
ALOFT...VENTILATION RATES WILL LOWER ACROSS MOST OF THE AREA.
THE WEATHER MODELS DEPICT A BROAD HIGH PRESSURE AREA OVER THE DESERT
SOUTHWEST AND SOUTHERN ROCKIES FRIDAY INTO SATURDAY. SMALLER
ATMOSPHERIC WAVES WILL ROTATE AROUND THIS HIGH PRESSURE AREA AND
KICK OFF SCATTERED TO NUMEROUS WETTING THUNDERSTORMS. WESTERN AND
NORTHERN PORTIONS OF NM WILL MOST LIKELY EXPERIENCE THESE WAVES.
DRIER AND MORE STABLE AIR ALOFT WILL REMAINED CENTERED OVER EASTERN
NM. THE FLOW ALOFT WILL BE RATHER WEAK DURING THIS PERIOD SO SOME
POOR VENTILATION RATES SHOW UP IN AREAS. HIGH TEMPERATURES WILL
GENERALLY BE NEAR NORMAL WEST AND SEVERAL DEGREES ABOVE NORMAL EAST.
MINIMUM HUMIDITY VALUES WILL ALSO BE IN THE 20S EAST AND CANT RULE
OUT SOME UPPER TEENS. THUS CURING OF THE FINE OR GRASS FUELS WOULD MOST
LIKELY CONTINUE THERE.
BOTH THE GFS AND ECMWF MODELS SHOW AN UPTICK IN WETTING
THUNDERSTORMS OVER THE ENTIRE FORECAST AREA SUNDAY INTO EARLY NEXT
WEEK. THE UPPER HIGH WEAKENS SOME AND ALLOWS THE ATMOSPHERE TO
BECOME MORE UNSTABLE. ABUNDANT LOW LEVEL MOISTURE WOULD ALSO BEGIN
TO FILL IN ACROSS THE FORECAST AREA AND ALLOW FOR SCATTERED TO
NUMEROUS WETTING STORMS. THIS PERIOD COULD BECOME SOME SORT OF PSEUDO
MONSOON BURST EVENT. WILL CONTINUE TO MONITOR THE MODELS AND GET A
BETTER GAUGE FOR CONFIDENCE AS TIME GOES ON. CONDITIONS WOULD THEN
GRADUALLY IMPROVE SOME ACROSS THE EASTERN PLAINS.
50
&&
.AVIATION...
18Z TAF CYCLE
ABUNDANT MOISTURE WILL FLOW UP FROM MEXICO TODAY. SOUTHERN
PORTIONS OF THE FORECAST AREA WILL SEE AN INCREASE IN SH/TS
COVERAGE AS A RESULT. BASED ON MODEL FORECASTS GUP AND ROW HAVE THE
BEST SHOT OF EXPERIENCING SOME OF THIS MOISTURE. WILL USE VCSH AT
THIS TIME BECAUSE THE HEAVY CLOUD COVER WILL CREATE A MORE STABLE
SITUATION. MVFR CONDITIONS ARE NOT ANTICIPATED AT THIS TIME BUT MT
TOP OBSCD WILL BE POSSIBLE ACROSS THE SOUTH AS CIGS LOWER.
RAINFALL COULD CONTINUE MOST OF THE OVERNIGHT ACROSS THE SOUTH AND
LOWER CIGS EVEN FURTHER THERE. ALSO HAVE A VCSH AT SAF. ISOLD
CELLS COULD ROLL OFF THE SANGRE DE CRISTOS TOWARDS SAF THIS
AFTERNOON SO WILL BITE ON THAT BASED ON A HIGHER RESOLUTION WEATHER
MODEL. WILL MONITOR ACCORDINGLY. ADDITIONAL STORM COVERAGE
ANTICIPATED ACROSS THE AREA ON THURSDAY.
50
&&
.PRELIMINARY POINT TEMPS/POPS...
FARMINGTON...................... 62 88 64 87 / 10 10 10 20
DULCE........................... 51 83 54 84 / 10 20 20 30
CUBA............................ 54 80 56 83 / 10 20 20 30
GALLUP.......................... 56 81 58 82 / 20 20 30 30
EL MORRO........................ 53 74 54 78 / 20 30 30 40
GRANTS.......................... 55 77 56 81 / 20 20 20 30
QUEMADO......................... 54 76 56 80 / 40 40 30 30
GLENWOOD........................ 60 78 61 82 / 50 50 30 20
CHAMA........................... 48 77 50 78 / 20 30 30 40
LOS ALAMOS...................... 56 80 58 83 / 10 20 20 20
PECOS........................... 55 78 57 81 / 20 10 10 20
CERRO/QUESTA.................... 51 80 53 82 / 10 20 20 20
RED RIVER....................... 48 72 50 75 / 20 30 30 40
ANGEL FIRE...................... 47 76 48 79 / 20 30 30 30
TAOS............................ 52 82 54 85 / 10 20 10 20
MORA............................ 53 78 54 81 / 10 10 20 20
ESPANOLA........................ 56 86 58 88 / 10 10 10 10
SANTA FE........................ 56 78 58 81 / 20 20 10 20
SANTA FE AIRPORT................ 59 85 60 86 / 20 10 10 20
ALBUQUERQUE FOOTHILLS........... 63 81 62 86 / 20 20 20 20
ALBUQUERQUE HEIGHTS............. 65 84 65 87 / 20 20 10 20
ALBUQUERQUE VALLEY.............. 63 85 64 89 / 20 10 10 5
ALBUQUERQUE WEST MESA........... 65 84 66 89 / 20 10 10 10
LOS LUNAS....................... 63 84 64 89 / 20 20 10 10
RIO RANCHO...................... 64 84 65 89 / 20 10 10 20
SOCORRO......................... 64 81 65 90 / 30 30 10 5
SANDIA PARK/CEDAR CREST......... 58 80 61 83 / 20 20 20 30
TIJERAS......................... 59 82 60 85 / 20 20 20 20
MORIARTY/ESTANCIA............... 59 82 58 85 / 20 20 10 20
CLINES CORNERS.................. 58 81 59 83 / 20 20 10 30
GRAN QUIVIRA.................... 59 76 59 84 / 30 20 10 20
CARRIZOZO....................... 62 76 62 85 / 40 30 10 5
RUIDOSO......................... 57 70 60 79 / 50 40 20 20
CAPULIN......................... 56 86 59 86 / 5 10 10 10
RATON........................... 55 88 56 87 / 5 10 5 10
SPRINGER........................ 57 89 57 90 / 5 10 5 10
LAS VEGAS....................... 55 84 56 85 / 10 10 10 20
CLAYTON......................... 63 93 64 94 / 5 5 0 0
ROY............................. 60 90 62 91 / 5 10 0 5
CONCHAS......................... 66 95 66 96 / 5 5 0 5
SANTA ROSA...................... 65 92 65 94 / 10 5 0 5
TUCUMCARI....................... 68 96 68 98 / 5 5 0 0
CLOVIS.......................... 65 91 66 93 / 10 5 0 0
PORTALES........................ 65 91 66 93 / 10 5 0 0
FORT SUMNER..................... 66 92 67 95 / 10 5 0 0
ROSWELL......................... 68 93 68 95 / 20 10 0 0
PICACHO......................... 62 83 61 89 / 30 20 5 5
ELK............................. 59 76 59 83 / 50 30 10 10
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 2 AM MDT THURSDAY FOR THE FOLLOWING ZONES...
NMZ508-526.
&&
$$
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
1127 AM MDT WED AUG 28 2013
.AVIATION...
18Z TAF CYCLE
ABUNDANT MOISTURE WILL FLOW UP FROM MEXICO TODAY. SOUTHERN
PORTIONS OF THE FORECAST AREA WILL SEE AN INCREASE IN SH/TS
COVERAGE AS A RESULT. BASED ON MODEL FORECASTS GUP AND ROW HAVE THE
BEST SHOT OF EXPERIENCING SOME OF THIS MOISTURE. WILL USE VCSH AT
THIS TIME BECAUSE THE HEAVY CLOUD COVER WILL CREATE A MORE STABLE
SITUATION. MVFR CONDITIONS ARE NOT ANTICIPATED AT THIS TIME BUT MT
TOP OBSCD WILL BE POSSIBLE ACROSS THE SOUTH AS CIGS LOWER.
RAINFALL COULD CONTINUE MOST OF THE OVERNIGHT ACROSS THE SOUTH AND
LOWER CIGS EVEN FURTHER THERE. ALSO HAVE A VCSH AT SAF. ISOLD
CELLS COULD ROLL OFF THE SANGRE DE CRISTOS TOWARDS SAF THIS
AFTERNOON SO WILL BITE ON THAT BASED ON A HIGHER RESOLUTION WEATHER
MODEL. WILL MONITOR ACCORDINGLY. ADDITIONAL STORM COVERAGE
ANTICIPATED ACROSS THE AREA ON THURSDAY.
50
&&
.PREV DISCUSSION...928 AM MDT WED AUG 28 2013...
WATER VAPOR LOOP CONTINUES TO SUPPORT A WELL DEFINED INVERTED
TROUGH AXIS PUSHING SLOWLY NORTH ACROSS SOUTHERN NM. LATEST
CIRA BLENDED TPW VALUES ARE HOVERING AT 100-125 PCT OF NORMAL.
SIGNIFICANT CLOUD COVER PUSHING NORTH INTO FAR SOUTHERN AREAS
OF THE CWA IS INHIBITING WARMING BUT THE 15Z LAPS DATA SHOWS A
DESTABILIZING AIRMASS MOVING SLOWLY NORTHWARD FROM THE EL PASO
AREA. LATEST SHORT-TERM MODEL GUIDANCE INCLUDING THE HRRR AND RUC
SHOW WIDESPREAD SHRA/TSRA DEVELOPMENT BY EARLY THIS AFTERNOON
IN THIS AREA SHIFTING NORTH WITH VERY LITTLE ACTIVITY OVER THE
REMAINDER OF NM. RAISED POPS TO LIKELY FOR MORE OF SOUTHERN
LINCOLN AND CATRON COUNTIES AND ADDED MORE OF A CHAVES COUNTY
AS WELL TO MENTION.
GUYER
.PREV DISCUSSION...316 AM MDT WED AUG 28 2013...
ELY WAVE/UPPER LEVEL CIRCULATION OVER TEXAS PANHANDLE THROWING A
LITTLE KINK IN THE FLOW AROUND UPPER HIGH CENTER OVER MISSOURI.
SOUTHERLY/SELY FLOW ALOFT CONTINUING TO TAP MID AND UPPER LEVEL
SUBTROPICAL MOISTURE EARLY THIS MORNING. THUNDERSTORM ACTIVITY
WILL BE ON THE INCREASE TODAY...ESPECIALLY FOR SOUTHERN AREAS
WHERE PWATS RISE TO NEAR AN INCH. ELSEWHERE...ISOLATED STORMS OVER
THE NORTHERN MOUNTAIN WILL LIKELY GET A LATE START AS SUBSIDENCE
ON THE BACK/WEST SIDE OF UPPER LEVEL WAVE KEEPS DRY UPPER LEVEL
AIR OVER THIS ARE LONGER. MODERATE TO STRONG MID-LEVEL SPEED MAX
ASSOCIATED WITH YET ANOTHER ELY WAVE MOVES THROUGH THE SOUTHERN
ZONES THIS EVENING. THIS FEATURE LIKELY TO KEEP SOME STORMS GOING
OVER THE SW MOUNTAINS OVERNIGHT.
DEEP MOISTURE ON THE RELATIVELY STRONG SOUTH/SELY WINDS AT THE SFC
AND ALOFT SURGES NORTHWARD TONIGHT AND THURSDAY MORNING...WITH A HEALTHY
CROP OF SCT STORMS EXPECTED THURSDAY. ADDITIONALLY...1 INCH PWAT ISOLINE SURGES
NORTHWARD INTO NORTHERN NM THURSDAY MORNING...MAKING SCATTERED
HEAVY RAINERS A VERY GOOD BET. FAVORED AREAS AT THIS POINT LIKELY
THE SOUTHWEST AND SOUTH CENTRAL MOUNTAINS. ISSUED A FLASH FLOOD
WATCH FOR THESE TWO ZONES GIVEN THE SUSCEPTIBILITY OF THE WHITEWATER
BALDY AND LITTLE BEAR BURN SCARS.
UPPER HIGH BUILDS BACK WESTWARD...NOW CENTERED OVER CENTRAL
COLORADO THURSDAY EVENING. SUBTROPICAL MOISTURE PLUME SHIFTS WWD
BUT PLENTY OF RESIDUAL MOISTURE FOR SCT CONVECTION WESTERN AND NRN
MOUNTAINS WITH ISOLD STORMS ELSEWHERE. SUBTROPICAL MOISTURE PLUME WRAPS
AROUND UPPER HIGH CIRCULATION...MOVING BACK INTO NORTHERN AND CENTRAL NM
FOR THE WEEKEND. COMBINATION OF ABOVE AVG PWATS AND ABOVE AVG SFC
TEMPS SHOULD LEAD TO HEALTHY ROUNDS OF AFTERNOON AND EVENING
CONVECTION EACH DAY THIS WEEKEND INTO EARLY NEXT WEEK.
33
.FIRE WEATHER...
ATMOSPHERIC MOISTURE WILL BE ON THE INCREASE TODAY INTO THURSDAY AS
AN EASTERLY WAVE MOVES ACROSS NORTHERN MEXICO AND SOUTHERN AZ/NM.
CHANCES FOR WETTING RAIN AND RELATIVE HUMIDITIES WILL BE TRENDING UP
AS WELL...ESPECIALLY SOUTH AND WEST. GOOD TO EXCELLENT HUMIDITY
RECOVERIES FORECAST TO PERSIST MOST AREAS. THROUGH FRIDAY...LOWEST
HUMIDITIES AND LOWEST CHANCES FOR WETTING RAIN WILL BE EASTERN
PLAINS...CLOSER TO THE SUBSIDENT SIDE OF THE UPPER HIGH CIRCULATION.
CONVECTIVE RECYCLING MODE THROUGH THE WEEKEND WITH THE UPPER HIGH
ANCHORED OVER THE AREA. SOME DRYING/WARMING FORECAST THROUGH THE
WEEKEND WITH NO ADDITIONAL INFLUX OF MOISTURE. DECENT AGREEMENT
BETWEEN THE 00Z GFS AND ECMWF SOLUTIONS OF THE POSITION OF THE UPPER
HIGH THROUGH THE MIDDLE OF NEXT WEEK OVER OUR AREA...WITH ANY
MONSOONAL MOISTURE PLUME MAINLY WEST OF NEW MEXICO OVER ARIZONA.
EASTERN PLAINS LOOK TO HAVE LITTLE TO NO CHANCE FOR WETTING RAINS
THROUGH THE MIDDLE OF NEXT WEEK. NEAR-TERM CONTINUED DRYING OF FINE
FUELS EASTERN PLAINS LOOKS LIKE A GOOD BET.
11
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR THE FOLLOWING ZONES...
NMZ508-526.
&&
$$
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
928 AM MDT WED AUG 28 2013
.UPDATE...
WATER VAPOR LOOP CONTINUES TO SUPPORT A WELL DEFINED INVERTED
TROUGH AXIS PUSHING SLOWLY NORTH ACROSS SOUTHERN NM. LATEST
CIRA BLENDED TPW VALUES ARE HOVERING AT 100-125 PCT OF NORMAL.
SIGNIFICANT CLOUD COVER PUSHING NORTH INTO FAR SOUTHERN AREAS
OF THE CWA IS INHIBITING WARMING BUT THE 15Z LAPS DATA SHOWS A
DESTABILIZING AIRMASS MOVING SLOWLY NORTHWARD FROM THE EL PASO
AREA. LATEST SHORT-TERM MODEL GUIDANCE INCLUDING THE HRRR AND RUC
SHOW WIDESPREAD SHRA/TSRA DEVELOPMENT BY EARLY THIS AFTERNOON
IN THIS AREA SHIFTING NORTH WITH VERY LITTLE ACTIVITY OVER THE
REMAINDER OF NM. RAISED POPS TO LIKELY FOR MORE OF SOUTHERN
LINCOLN AND CATRON COUNTIES AND ADDED MORE OF A CHAVES COUNTY
AS WELL TO MENTION.
GUYER
&&
.PREV DISCUSSION...527 AM MDT WED AUG 28 2013...
.AVIATION...
12Z TAF CYCLE
VFR CONDITIONS TO PERSIST THROUGH THE NEXT 24HRS. LOOK FOR A
GRADUAL LOWERING OF VFR CIGS AT KROW WITH MOISTURE INCREASING FROM
THE SOUTH. ISOLATED SHOWERS MAY COME CLOSE TO KGUP LATE TODAY...
BUT VFR CONDITIONS STILL ANTICIPATED. WINDS WILL GENERALLY BE
LIGHT.
11
.PREV DISCUSSION...316 AM MDT WED AUG 28 2013...
ELY WAVE/UPPER LEVEL CIRCULATION OVER TEXAS PANHANDLE THROWING A
LITTLE KINK IN THE FLOW AROUND UPPER HIGH CENTER OVER MISSOURI.
SOUTHERLY/SELY FLOW ALOFT CONTINUING TO TAP MID AND UPPER LEVEL
SUBTROPICAL MOISTURE EARLY THIS MORNING. THUNDERSTORM ACTIVITY
WILL BE ON THE INCREASE TODAY...ESPECIALLY FOR SOUTHERN AREAS
WHERE PWATS RISE TO NEAR AN INCH. ELSEWHERE...ISOLATED STORMS OVER
THE NORTHERN MOUNTAIN WILL LIKELY GET A LATE START AS SUBSIDENCE
ON THE BACK/WEST SIDE OF UPPER LEVEL WAVE KEEPS DRY UPPER LEVEL
AIR OVER THIS ARE LONGER. MODERATE TO STRONG MID-LEVEL SPEED MAX
ASSOCIATED WITH YET ANOTHER ELY WAVE MOVES THROUGH THE SOUTHERN
ZONES THIS EVENING. THIS FEATURE LIKELY TO KEEP SOME STORMS GOING
OVER THE SW MOUNTAINS OVERNIGHT.
DEEP MOISTURE ON THE RELATIVELY STRONG SOUTH/SELY WINDS AT THE SFC
AND ALOFT SURGES NORTHWARD TONIGHT AND THURSDAY MORNING...WITH A HEALTHY
CROP OF SCT STORMS EXPECTED THURSDAY. ADDITIONALLY...1 INCH PWAT ISOLINE SURGES
NORTHWARD INTO NORTHERN NM THURSDAY MORNING...MAKING SCATTERED
HEAVY RAINERS A VERY GOOD BET. FAVORED AREAS AT THIS POINT LIKELY
THE SOUTHWEST AND SOUTH CENTRAL MOUNTAINS. ISSUED A FLASH FLOOD
WATCH FOR THESE TWO ZONES GIVEN THE SUSCEPTIBILITY OF THE WHITEWATER
BALDY AND LITTLE BEAR BURN SCARS.
UPPER HIGH BUILDS BACK WESTWARD...NOW CENTERED OVER CENTRAL
COLORADO THURSDAY EVENING. SUBTROPICAL MOISTURE PLUME SHIFTS WWD
BUT PLENTY OF RESIDUAL MOISTURE FOR SCT CONVECTION WESTERN AND NRN
MOUNTAINS WITH ISOLD STORMS ELSEWHERE. SUBTROPICAL MOISTURE PLUME WRAPS
AROUND UPPER HIGH CIRCULATION...MOVING BACK INTO NORTHERN AND CENTRAL NM
FOR THE WEEKEND. COMBINATION OF ABOVE AVG PWATS AND ABOVE AVG SFC
TEMPS SHOULD LEAD TO HEALTHY ROUNDS OF AFTERNOON AND EVENING
CONVECTION EACH DAY THIS WEEKEND INTO EARLY NEXT WEEK.
33
.FIRE WEATHER...
ATMOSPHERIC MOISTURE WILL BE ON THE INCREASE TODAY INTO THURSDAY AS
AN EASTERLY WAVE MOVES ACROSS NORTHERN MEXICO AND SOUTHERN AZ/NM.
CHANCES FOR WETTING RAIN AND RELATIVE HUMIDITIES WILL BE TRENDING UP
AS WELL...ESPECIALLY SOUTH AND WEST. GOOD TO EXCELLENT HUMIDITY
RECOVERIES FORECAST TO PERSIST MOST AREAS. THROUGH FRIDAY...LOWEST
HUMIDITIES AND LOWEST CHANCES FOR WETTING RAIN WILL BE EASTERN
PLAINS...CLOSER TO THE SUBSIDENT SIDE OF THE UPPER HIGH CIRCULATION.
CONVECTIVE RECYCLING MODE THROUGH THE WEEKEND WITH THE UPPER HIGH
ANCHORED OVER THE AREA. SOME DRYING/WARMING FORECAST THROUGH THE
WEEKEND WITH NO ADDITIONAL INFLUX OF MOISTURE. DECENT AGREEMENT
BETWEEN THE 00Z GFS AND ECMWF SOLUTIONS OF THE POSITION OF THE UPPER
HIGH THROUGH THE MIDDLE OF NEXT WEEK OVER OUR AREA...WITH ANY
MONSOONAL MOISTURE PLUME MAINLY WEST OF NEW MEXICO OVER ARIZONA.
EASTERN PLAINS LOOK TO HAVE LITTLE TO NO CHANCE FOR WETTING RAINS
THROUGH THE MIDDLE OF NEXT WEEK. NEAR-TERM CONTINUED DRYING OF FINE
FUELS EASTERN PLAINS LOOKS LIKE A GOOD BET.
11
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR THE FOLLOWING ZONES...
NMZ508-526.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
1134 PM MDT TUE AUG 27 2013
.AVIATION...
06Z TAF CYCLE
VFR CONDITIONS WILL PREVAIL FOR THE OVERNIGHT PERIOD. ONE
EXCEPTION IS ALONG AND SE OF A LINE FROM KROW TO KCVS WHERE SOME
MVFR CIGS COULD DEVELOP BETWEEN 10 AND 14Z. CONFIDENCE IS LOW
ATTM...HOWEVER...DUE TO THE ABUNDANT HIGH CLOUDS ALREADY IN THIS
AREA. EXPECT A FEW STORMS TO DEVELOP AROUND 18Z WEDNESDAY ACROSS
THE HIGH TERRAIN...BEFORE SLOWLY MOVING NORTH THRU THE AFTN. NOT
EXPECTING MUCH MORE ACTIVITY THAN WHAT WAS OBSERVED TODAY...
ESPECIALLY ACROSS THE NORTH. MOISTURE WILL BEGIN TO CREEP
NORTHWARD FROM MEXICO...THUS THE SC AND SW MTNS COULD BE A BIT
MORE ACTIVE. LOCALLY HEAVY RAIN...BRIEF MVFR CIGS/VSBYS WILL BE
THE MAIN THREATS WITH THESE STORMS.
34
&&
.PREV DISCUSSION...915 PM MDT TUE AUG 27 2013...
UPDATED ZFP JUST SENT. TRIMMED POPS FOR REMAINDER OF TONIGHT.
CONVECTION CONTINUES TO WANE AND DESPITE THE INCREASE IN
PW...DEEP EASTERLY WINDS ALF ON EVENING RAOBS INDICATED A STABLE
AIRMASS. LATEST RUC13 INDICATES MINIMAL QPF AS WELL FOR THE
OVERNIGHT.
.PREV DISCUSSION...300 PM MDT TUE AUG 27 2013... HAVE
MADE SOME FAIRLY SUBSTANTIAL CHANGES TO THE MEDIUM AND EXTENDED
RANGE FORECAST IN FAVOR OF A MUCH WETTER PATTERN. THE LATEST CIRA
BLENDED TPW IMAGERY SHOWS A DEEP POOL OF 150 PCT OF NORMAL
MOISTURE ENTRENCHED OVER BAJA MEXICO AND NEARLY ALL OF TX.
MOISTURE TRANSPORT WILL BE IMPRESSIVE AS WE PROGRESS THRU THE END
OF THIS WEEK INTO THE LABOR DAY HOLIDAY AS A LARGE INVERTED TROUGH
SHIFTS NW OVER NM.
CURRENTLY THERE IS A RELATIVELY STABLE AND DRY AIRMASS IN PLACE OVER
CENTRAL AND EASTERN NM...LEADING TO ONLY ISOLATED STORM COVERAGE AT
BEST FOR FAR WESTERN NM. THERE WILL BE LITTLE CHANGE TO THIS THEME
THRU WEDNESDAY AS INDICATED BY THE BULK OF OPERATIONAL GUIDANCE...
INCLUDING HPC PROBABILISTIC QPF AND MODEL ENSEMBLES. AN UPTICK IN
COVERAGE IS HOWEVER EXPECTED WEDNESDAY FOR THE GILA REGION TO THE
SOUTH CENTRAL MTS.
THE AFOREMENTIONED MOISTURE SURGE ADVECTS QUICKLY NW ACROSS NM
STARTING THURSDAY. PWAT VALUES ARE PROGGED TO AVERAGE 1 TO 1.2
INCHES WHICH WILL APPROACH 150 PCT OF NORMAL. INSTABILITY IN ASSCN
WITH THE WELL DEFINED INVERTED TROUGH WILL RESULT IN AT LEAST SCT
COVERAGE FROM THE GILA REGION NORTH ACROSS THE CONT DVD INTO THE
NORTHERN MTS. STEERING FLOW WILL BE WEAKER WITHIN THE TROUGH AXIS
THUS LCL HEAVY RAIN IS POSSIBLE. THE GFS AND ECMWF BOTH INDICATE
MOIST INSTABILITY WITH THIS WAVE WILL BECOME TRAPPED UNDER AN
UPPER RIDGE SHIFTING BACK SOUTH OVER THE REGION FRIDAY. THIS WILL
WEAKEN STEERING FLOW FURTHER ELEVATING THE POTENTIAL FOR HEAVY RAIN.
VERY LITTLE CHANGE IS ADVERTISED BY THE GFS WITHIN A WELL DEFINED
STRONGLY UNSTABLE MOISTURE AXIS CENTERED OVER THE CONT DVD BOTH
SATURDAY AND SUNDAY. THE POTENTIAL FOR LCL HEAVY RAIN WILL BE THE
GREATEST FOR THIS PERIOD. THE 12Z ECMWF HAS TRENDED MUCH DRIER WITH
A SPRAWLING UPPER RIDGE OVER THE DESERT SW. SINCE THIS IS A BIG
CHANGE FROM PREVIOUS TRENDS HAVE PUSHED THAT ASIDE FOR NOW AND
RAISED POPS THRU THE HOLIDAY WEEKEND. A SPECIAL WX STATEMENT MAY BE
ON THE HORIZON WITH POTENTIAL FOR A FLASH FLOOD WATCH IF TRENDS
CONTINUE TO INDICATE HEAVY RAIN. THIS SHOULD SERVE TO RAISE PUBLIC
AWARENESS OF A RETURN TO A STRONGER MONSOON PATTERN AS A SIGNIFICANT
NUMBER OF OUTDOOR LABOR DAY ACTIVITIES WILL BE ONGOING.
THE GFS INTRODUCES ANOTHER WELL DEFINED MOIST EASTERLY WAVE FOR
MONDAY INTO THE MIDDLE OF NEXT WEEK WITH A FOCUS OVER NORTHERN/
WESTERN NM. THE HPC 8-14 DAY OUTLOOK INDICATES A GOOD CHANCE FOR
ABOVE NORMAL PRECIPITATION IN THIS AREA...SO WILL CONTINUE THE
TREND OF RAISING POPS.
GUYER
.FIRE WEATHER...
A STRONG UPPER LEVEL HIGH PRESSURE SYSTEM CENTERED OVER KANSAS CITY
THIS AFTERNOON WILL WEAKEN SOME AND GRADUALLY SHIFT ITS CENTER
WESTWARD OVER SOUTHERN CO BY THURSDAY. MEANWHILE AN EASTERLY WAVE
TRACKING SLOWLY NORTHWESTWARD ACROSS NORTHERN MEXICO WILL SPREAD
RICHER MOISTURE INTO SOUTHWEST PARTS OF THE FORECAST AREA WEDNESDAY.
A PORTION OF THIS WAVES ENERGY IS PROGGED TO LIFT NORTHWARD THROUGH
AZ THURSDAY AND FRIDAY. THIS SHOULD FUNNEL BETTER MONSOON MOISTURE
ACROSS MORE OF WESTERN NM AND TO A LESSER EXTENT CENTRAL PARTS OF
THE STATE WITH SCATTERED TO NUMEROUS THUNDERSTORMS MAINLY ALONG AND
WEST OF THE CENTRAL MOUNTAIN CHAIN BOTH DAYS. SUBSIDENCE CLOSER TO
THE CENTER OF THE HIGH PRESSURE SYSTEM SHOULD KEEP THE PLAINS ON THE
DRIER SIDE THROUGH THE END OF THE WORK WEEK WITH GRADUALLY WARMING
HIGH TEMPERATURES. THURSDAY AND FRIDAY...HIGHS ON THE PLAINS SHOULD
VARY FROM 6 TO 12 DEGREES ABOVE NORMAL WHILE WESTERN READINGS VARY
FROM NEAR NORMAL TO AROUND 3 DEGREES BELOW NORMAL.
OVER THE WEEKEND THE UPPER LEVEL HIGH PRESSURE SYSTEM WILL WEAKEN
SIGNIFICANTLY AND BROADEN OVER CO AND NM ALLOWING A RICH MONSOON
MOISTURE PLUME TO SPREAD UNDERNEATH THE RIDGE AND MORE SQUARELY OVER
NEW MEXICO. WITH PWAT VALUES AROUND 1 TO 1.5 INCHES ACROSS MUCH OF
WESTERN AND CENTRAL PARTS OF THE FORECAST AREA...THUNDERSTORMS WILL
BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL WITH A THREAT OF
FLASH FLOODING THURSDAY THROUGH SUNDAY. STORM MOTIONS WILL ALSO
SLOW TO A CRAWL AS THE WEAKENING DOME OF HIGH PRESSURE SPREADS OVER
THE REGION...ADDING TO THE FLASH FLOOD THREAT. THE PLAINS WILL ALSO
HAVE A CHANCE FOR WETTING PRECIP OVER THE WEEKEND...BUT HIGHER
PROBABILITIES SHOULD FAVOR CENTRAL AND WESTERN AREAS.
THE GFS AND ECMWF HAVE FAIR AGREEMENT THAT THE UPPER HIGH WILL
SLOWLY RESTRENGTHEN AND RECENTER NEAR KS/OK EARLY IN THE COMING WORK
WEEK. THIS WOULD ALLOW A LITTLE DRIER AIR TO FUNNEL INTO EASTERN
AREAS AND TIGHTEN THE FOCUS OF THE MONSOON MOISTURE PLUME MORE ALONG
THE CONTINENTAL DIVIDE. THIS WOULD ALSO ALLOW EASTERN HIGH
TEMPERATURES TO WARM...AFTER SOME POTENTIALLY COOLER READINGS
AREAWIDE OVER THE WEEKEND.
RELATIVE HUMIDITIES SHOULD REMAIN ABOVE CRITICAL THRESHOLDS
WEDNESDAY THROUGH MONDAY...WITH GOOD TO EXCELLENT OVERNIGHT
RECOVERIES. VENT RATES WILL GENERALLY BE GOOD OR BETTER...EXCEPT FOR
POCKETS OF POOR DISPERSION ASSOCIATED WITH PERIODS OF GREATER
THUNDERSTORM COVERAGE ACROSS CENTRAL AND WESTERN AREAS.
44
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
932 PM EDT THU AUG 29 2013
.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO SLOWLY MOVE SOUTH THROUGH THE AREA
TONIGHT. HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTH
FRIDAY AND SATURDAY. THE HIGH WILL GRADUALLY SHIFT OFFSHORE WITH
ANOTHER COLD FRONT APPROACHING TUESDAY BEFORE MOVING OFFSHORE ON
WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 535 PM THURSDAY...THE FRONT ON SATELLITE AND RADAR IMAGERY
IS MOVING SOUTHWEST ACROSS EASTERN NC EARLY THIS EVENING AND @ 530
PM WAS LOCATED ROUGHLY ALONG A GREENVILLE TO TO NEWPORT LINE.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WERE OCCURRING ALONG AND
IN VICINITY OF THE BOUNDARY. THE HRRR MODEL WAS IN SYNC WITH
CURRENT RADAR TRENDS AND INDICATES THAT SHOWER THREAT WILL ENDING
SHORTLY AFTER 00Z AIDED BY LOSS OF SURFACE HEATING AND THE FRONT
MOVING OUT OF THE AREA. MODERATE NORTHEAST SURGE FOLLOWS THE FRONT
BUT IS FORECAST TO SUBSIDE AFTER MIDNIGHT WITH THE POTENTIAL FOR
PATCHY FOG IN AREAS THAT DECOUPLE. A MORE LIKELY SCENARIO IS THE
DEVELOPMENT OF WIDESPREAD LOW STRATUS CLOUDS AFTER 06Z AS THE
BOUNDARY LAYER FLOW REMAINS WELL MIXED ABOVE A SHALLOW
NOCTURNAL/FRONTAL INVERSION. FORECAST LOW TEMPERATURES WILL RANGE
FROM THE MIDDLE 60S INLAND TO THE LOWER 70S BEACHES.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
AS OF 245 PM THURSDAY...FRIDAY WILL BE CHARACTERIZED BY A SLIGHTLY
DRIER AIRMASS WITH WARM TEMPERATURES IN THE MIDDLE TO UPPER 80S
AWAY FROM THE IMMEDIATE COAST. DEWPOINTS WILL DROP INTO THE UPPER
60S WITH A LIGHT NORTHEAST WIND AS HIGH PRESSURE BUILDS SOUTH
ACROSS THE MID-ATLANTIC. MAY START THE DAY WITH SOME LOW STRATUS
BUT IT SHOULD DISSIPATE AS THE DRIER AIR STARTS TO MIX TO THE
SURFACE BY MID MORNING.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
AS OF 230 PM THU...HIGH PRESSURE WILL BE THE DOMINANT FEATURE
ACROSS THE AREA THIS WEEKEND INTO EARLY NEXT WEEK. HIGH PRESSURE
WILL TRANSITION OFF THE COAST SAT WHILE A BOUNDARY PUSHES BACK
NORTH OVER THE REGION BY LATE AFTERNOON AS A WEAK WARM FRONT.
LITTLE IF ANY PRECIP IS EXPECTED TO OCCUR AS BOUNDARY LAYER WILL
REMAIN DRY...THOUGH AN ISO SHOWER/STORM POSSIBLE INLAND WITH SEA
BREEZE PROPAGATION AND WILL MAINTAIN ISOLATED POPS SAT
AFTERNOON...WITH BEST CHANCES ACROSS SOUTHERN CWA. SW RETURN FLOW
INCREASES SUN BRINGING WARM/MOIST CONDITIONS BACK TO THE AREA WITH
FORECAST SOUNDINGS INDICATING PWATS NEAR 2 INCHES. WILL CONTINUE
LOW END CHANCE POPS INLAND AND SLIGHT E OF HWY 17.
BY MON AN UPPER LEVEL TROUGH OVER SOUTH CENTRAL CANADA WILL DIG
SOUTH AND EAST INTO THE GREAT LAKES REGION. SHORT WAVE ENERGY IN
BROAD SW FLOW WILL MOVE ACROSS THE REGION BRINGING A BETTER CHANCE
FOR ORGANIZED CONVECTION IN TANDEM WITH PIEDMONT TROUGH AND SEA
BREEZE...AND HAVE MAINTAINED CHANCE POPS ACROSS THE REGION. FOR
TUES...THE UPPER TROUGH WILL MOVE EAST FROM THE GREAT LAKES INTO
THE NORTHEASTERN STATES...DRAGGING A COLD FRONT THROUGH EASTERN NC
LATE TUE INTO TUE NIGHT. WILL CONTINUE GOOD CHANCE POPS TUE
TAPERING OFF BEHIND THE FRONT TUE NIGHT INTO WED. TEMPS THROUGH
THE PERIOD WILL BE NEAR CLIMO...WITH HIGHS GENERALLY IN THE MID
80S TO AROUND 90 DEGREES. THE WARMEST DAYS OF THE PERIOD LOOK LIKE
SUN AND MON. SLIGHTLY COOLER AND DRIER AIRMASS EXPECTED BEHIND THE
FRONT FOR WED/THU...THOUGH NO SIG TEMP SWINGS EXPECTED.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
SHORT TERM /TONIGHT AND FRIDAY/...
AS OF 535 PM THURSDAY...SHOWER THREAT WILL ENDING AT THE TAF SITES
AROUND 00Z. MAIN CONCERN TONIGHT IS THE POTENTIAL FOR WIDESPREAD
IFR CONDITIONS. A MODERATE NORTHEAST SURGE IS OCCURRING BEHIND A
SOUTHWEST MOVING COLD FRONTAL BOUNDARY WHICH IS MOVING THROUGH THE
TAF SITES EARLY THIS EVENING. THIS SURGE IS EXPECTED TO SUBSIDE
AFTER 06Z AND ALONG WITH CLEARING BEHIND THE FRONT COULD LEAD TO
PATCHY FOG ESPECIALLY IN AREAS THAT RECEIVED RAINFALL AND WHERE
WINDS DECOUPLE. WHAT IS MORE LIKELY TO OCCUR IS THAT WIDESPREAD
STRATUS WILL DEVELOP AS THE BOUNDARY LAYER ABOVE THE SURFACE
REMAINS WELL MIXED OVERNIGHT. ALL OF THE AVIATION GUIDANCE FROM
BUFKIT TO THE UPS FOG TOOL TO THE MOS IS INDICATING IFR CEILINGS
AND/OR VISIBILITIES AFTER 06Z SO WILL CONTINUE TREND ESTABLISHED
IN PREVIOUS TAFS AND FORECAST IFR AROUND 08Z THROUGH 14Z FRIDAY.
VFR CONDITIONS THEN A FORECAST TO PREVAIL AFTER THE FOG/STRATUS
DISSIPATE AS HIGH PRESSURE AND DRIER AIR BUILD OVER THE REGION.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM THU...PRED VFR CONDITIONS EXPECTED THROUGH THE
PERIOD. A COLD FRONT WILL APPROACH FROM THE WEST MONDAY
NIGHT...MOVING THROUGH EASTERN NC LATE TUE AND TUE NIGHT. SCT
MAINLY DIURNAL SHOWERS/TSTMS POSSIBLE SUN THROUGH TUE WITH PERIODS
OF SUB-VFR POSSIBLE. WITH CALM TO LIGHT WINDS OVERNIGHT AND MOIST
BL...COULD SEE PATCHY FOG/STRATUS EACH NIGHT AND EARLY MORNING.
&&
.MARINE...
SHORT TERM /TONIGHT AND FRIDAY/...
AS OF 930 PM THURSDAY...THE COLD FRONT HAS MOVED SOUTH OF THE
WATERS THIS EVENING WITH MODERATE TO STRONG NORTHEASTERLY FLOW NOW
OCCURRING OVER THE WATERS WITH SUSTAINED WINDS TO 20 KT WITH
FREQUENT GUSTS TO 25 KT OVER THE NORTHERN AND CENTRAL WATERS. THIS
HAS RESULTED IN SEAS BUILDING TO 5 TO 6 FT AND NECESSITATED THE
ISSUANCE OF SMALL CRAFT ADVISORY FOR THE PAMLICO SOUND AND THE
NORTHERN AND CENTRAL WATERS THROUGH 09Z FRIDAY. ELSEWHERE WINDS
AND SEAS WILL REMAIN JUST BELOW ADVISORY CRITERIA OVERNIGHT. THE
WINDS ARE FORECAST TO BEGIN TO SUBSIDE EARLY FRIDAY AS THE
GRADIENT RELAXES. ON FRIDAY NORTHEAST WINDS AROUND 15 KT IN THE
MORNING WILL SUBSIDE TO 10 KT LATE IN THE AFTERNOON. SEAS WILL
RANGE FROM 4 TO 6 FEET CENTRAL AND NORTH TO 2 TO 4 FEET
SOUTH...SUBSIDING TO 3 TO 5 FT NORTH AND CENTRAL FRIDAY.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM THU...HIGH PRESSURE WILL BE THE DOMINANT FEATURE OVER
THE WATERS THIS WEEKEND INTO EARLY NEXT WEEK. OVERALL EXPECT
PLEASANT BOATING CONDITIONS THIS WEEKEND WITH VEERING WINDS 5-15KT
AND SEAS 2-4FT. A COLD FRONT WILL APPROACH THE WATERS FROM THE
WEST MON NIGHT INTO TUE...MOVING THROUGH TUE NIGHT INTO EARLY WED
MORNING. A BRIEF PERIOD OF SCA CONDITIONS WILL BE POSSIBLE MONDAY
EVENING...MAINLY FOR THE CENTRAL WATERS...AS GRADIENT TIGHTENS
AHEAD OF APPROACHING FRONT. SWLY WINDS EXPECTED TO INCREASE TO
15-20KT WITH SEAS BUILDING TO 6FT ACROSS THE OUTER CENTRAL WATERS.
SW FLOW 10-20KT WILL CONTINUE INTO TUE WITH SEAS 5FT OR LESS.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EDT FRIDAY FOR AMZ135-150-152-
154.
&&
$$
SYNOPSIS...CTC
NEAR TERM...CTC/JME
SHORT TERM...CTC
LONG TERM...CQD
AVIATION...JME/CQD/LEP
MARINE...CTC/JME/CQD
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
316 PM EDT WED AUG 28 2013
.SYNOPSIS...
SCATTERED SHOWERS AND THUNDERSTORMS WILL OCCUR AHEAD OF A COLD
FRONT...WHICH SHOULD ARRIVE FROM THE NORTH LATE THURSDAY
AFTERNOON. THIS FRONT WILL STALL SOUTH OF CHARLESTON FRIDAY...BUT
IS EXPECTED TO RETURN NORTH THIS WEEKEND WITH HOT AND HUMID
CONDITIONS DEVELOPING EARLY NEXT WEEK. A STRONGER COLD FRONT WILL
ARRIVE FROM THE NORTH TUESDAY OR WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM WEDNESDAY...WARMER AND MORE MOIST AIRMASS IN PLACE
TODAY. TEMPS BETWEEN 85 AND 90 MOST PLACES WITH DEWPOINT TEMPS
AROUND 70 IN A SW FLOW BETWEEN TROUGH OF LOW PRESSURE INLAND AND WEAK
HIGH PRESSURE OFF SHORE. MID TO HIGH CLOUDS WILL CONTINUE TO
STREAM DOWN INTO THE CAROLINAS FROM ASSOCIATED CONVECTION/PCP
UPSTREAM ROUNDING THE TOP OF THE MID TO UPPER RIDGE. THESE CLOUDS
WILL SPREAD SOUTH FILTERING OUT THE SUN AND PRODUCING MOSTLY
CLOUDY SKIES THIS AFTERNOON...ESPECIALLY ACROSS NORTHERN TIER
COUNTIES. THIS WILL ACT TO SLOW DOWN HEATING IN PLACES AND PRODUCE
SLIGHTLY LOWER TEMPS...BUT AS OF NOW...EXPECTING TEMPS TO REACH
BETWEEN 85 AND 90 AIDED BY A WARMER DOWNSLOPE WESTERLY FLOW
THROUGH THE LOW LEVELS.
WITH A PREVAILING SOUTHWEST FLOW AT THE SURFACE...SEA BREEZE SHOULD
PENETRATE FARTHER INLAND OVER NORTH CAROLINA COUNTIES. MOISTURE
RICH AIR WILL PUSH INLAND BEHIND SEA BREEZE WITH GREATEST RISE IN
DEWPOINTS UP CLOSE TO 75 ACROSS NORTH CAROLINA COASTAL
COUNTIES...WHERE MODELS SHOW HIGHEST CAPE VALUES. DEWPOINT TEMPS
INLAND WILL DECREASE REMAINING BELOW 70 IN MOST PLACES. DECENT
SUBSIDENCE INVERSION ALOFT WILL KEEP MOST CONVECTIVE ACTIVITY AT
BAY THIS AFTERNOON...BUT CONVERGENCE ALONG SEA BREEZE COULD TRIGGER
ISLD SHWRS/TSTMS...MAINLY OVER NC COASTAL COUNTIES. ANOTHER FOCUS
OF CONVECTION WILL BE ALONG TROUGH INLAND...MAINLY WEST OF LOCAL
CWA...BUT CLOUDS STREAMING IN FROM THE NORTH WILL CONTINUE TO
INHIBIT THIS ACTIVITY. WILL KEEP WITH MAINLY ISOLATED FOR THIS
AFTERNOON AS SOME PCP COULD SHIFT INTO OUR NORTHWESTERN COUNTIES.
A LINGERING AREA OF MAINLY STRATIFORM PCP WILL ALSO TRACK MAINLY
ACROSS NORTH CAROLINA PRODUCING MAINLY LIGHTER PCP.
MID-LEVEL PERTURBATIONS WILL RIDE AROUND THE MID TO UPPER RIDGE
AS IT SHIFTS WEST PRODUCING A MORE DIRECT STEERING FLOW INTO OUR
AREA. AT THE MOMENT...WATER VAPOR SATELLITE IMAGERY SHOWING
ASSOCIATED CONVECTION WELL UPSTREAM OVER WEST VA/VA BORDER AND
FURTHER NORTH LINING UP NICELY WITH THESE SHORTWAVES. AS THESE
PERTURBATIONS MOVES SOUTH OVER NORTH CAROLINA THEY SHOULD ACT TO
INITIATE SOME CONVECTION...MAINLY NORTH BUT THEY MAY MOVE CLOSE
ENOUGH TO HELP ENHANCE ACTIVITY ALONG THE SEA BREEZE AND INLAND
TROUGH LATER TODAY.
PRECIPITABLE WATER VALUES WILL CONTINUE TO INCREASE REACHING JUST
OVER 2 INCHES THROUGH LATE DAY INTO TONIGHT...BUT THE MID LEVELS
REMAIN FAIRLY DRY AND LIFT WILL REMAIN RATHER WEAK THROUGH THIS
PERIOD. A DECENT CAP WILL REMAIN OVER THE AREA THROUGH THE DAY.
THEREFORE WILL CONTINUE TO INCLUDE ONLY ISOLATED TO LOW END SCT POPS
ACROSS MAINLY NORTH CAROLINA COUNTIES LATE DAY AND TONIGHT. CLOUDS
AND PCP OVERNIGHT WILL KEEP LOWS ABOVE NORMAL...LOWER TO MID 70S.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 3 PM WEDNESDAY...THE LONGWAVE TROUGH JUST OFF THE EAST COAST
WILL HAVE SEVERAL SHORTWAVES MOVE THROUGH IT OVER THE NEXT SEVERAL
DAYS. ONE SHORTWAVE WILL MOVE OFF THE CAROLINA COAST THIS
EVENING FOLLOWED BY A MUCH WEAKER ONE THURSDAY NIGHT. THIS IS ALL
OCCURRING WITHIN A LARGE REGION OF NORTHWEST FLOW ALOFT COMING
DOWN OFF THE RIDGE OVER THE PLAINS STATES.
A SURFACE COLD FRONT CURRENTLY OVER OHIO AND INDIANA WILL SWEEP
SOUTHEASTWARD TOMORROW...MOVING INTO THE EASTERN CAROLINAS DURING
THE LATE AFTERNOON AND EARLY EVENING HOURS. THIS TIMING IS IN
BETWEEN THE TWO SHORTWAVES ALOFT AND THERE ARE NO FAVORABLY
POSITIONED UPPER JETS TO ASSIST WITH SYNOPTIC LIFT. FOR THIS
REASON MY POPS ARE ONLY IN THE 20-40 PERCENT RANGE TOMORROW...ALL
THIS DESPITE A FRONT ARRIVING JUST AFTER PEAK HEATING ALONG WITH
SURFACE-BASED CAPE AS HIGH AS 1500 J/KG. THE BOUNDARY SHOULD DRIFT
SOUTH TO NEAR SAVANNAH GEORGIA FRIDAY BEFORE STALLING AND
RETURNING NORTH LATER IN THE WEEKEND. AS ONE WOULD EXPECT MODELS
ARE ALL OVER THE PLACE WITH THEIR DEPICTION OF WHERE SHOWERS AND
T-STORMS WILL MOST LIKELY BE TOMORROW. 09Z SREF POPS LOOK A GREAT
DEAL LIKE THE 12Z GFS WHICH GIVES SOME CONFIDENCE TO PLACING THE
BEST PRECIP POTENTIAL ALONG THE COAST THURSDAY AFTERNOON...SHIFTING
SOUTHWESTWARD TOWARD INTERIOR EASTERN SOUTH CAROLINA DURING THE
EVENING HOURS. STABLE POST-FRONTAL AIR SHOULD END ANY LINGERING
SHOWERS ACROSS SE NORTH CAROLINA AFTER MIDNIGHT.
FAIRLY WEAK INSTABILITY FRIDAY SHOULD PRECLUDE MUCH SHOWER
ACTIVITY ACROSS SE NORTH CAROLINA...BUT A LITTLE BETTER MOISTURE
IN THE VICINITY OF THE STALLED FRONT SHOULD PRODUCE 20-30 PERCENT
COVERAGE OF SHOWERS AND T-STORMS ACROSS EASTERN SOUTH CAROLINA.
FRIDAY NIGHT THE FRONT WILL BEGIN TO RETURN NORTHWARD...BUT ANY
INCREASE IN SHOWER COVERAGE SHOULD REMAIN OFFSHORE.
THE NAM AND GFS ARE IN VERY GOOD AGREEMENT WITH TEMPERATURE TRENDS
OVER THE NEXT COUPLE OF DAYS...AND MY FORECAST IS VERY CLOSER TO
BOTH. BOTH MODELS ARE MUCH WARMER THAN THE EXPERIMENTAL ECMWF MOS
FOR HIGH TEMPERATURES THURSDAY. MODELS SHOW THERE WILL BE AT
LEAST SCATTERED MID-LEVEL ALTOCUMULUS AT THE TOP OF THE LOW-
LEVEL MOISTURE PLUME NEAR 10000 FT AGL...BUT I HAVE DOUBTS IT WILL
REMAIN DENSE ENOUGH DURING THE DAYLIGHT HOURS TO HOLD TEMPERATURES
DOWN SIGNIFICANTLY.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 3 PM WEDNESDAY...NORMAL SUMMERTIME CONDITIONS TO START THE
PERIOD WITH RATHER ZONAL FLOW ALOFT AND TEMPS AT OR SLIGHTLY ABOVE
SEASONABLE LEVELS. WITH BERMUDA HIGH PRESSURE OFFSHORE AND TROUGHING
SLOWLY DEVELOPING AT 500MB...PIEDMONT TROUGH AND SEA BREEZE DIURNAL
CONVECTION WILL BE POSSIBLE EACH AFTN THROUGH THE WKND. EARLY NEXT
WEEK...TROUGH AT 500MB DEEPENS ACROSS THE EAST...REINFORCED BY A
SERIES OF SHORTWAVES DROPPING AROUND THE BASE. THIS TROUGH WILL PICK
UP THE MOISTURE FROM A WEAK TROPICAL WAVE NEAR FLORIDA...AND THIS
WILL ENHANCE CONVECTION/RAINFALL POTENTIAL ON MONDAY. HIGHEST POP
WILL BE SHOWN MONDAY FOR THIS REASON...BUT TEMPS WILL CONTINUE TO
WARM TO SEVERAL DEGREES ABOVE CLIMO FOR THE EARLY WEEK. THIS IMPULSE
WILL MOVE AWAY TUESDAY...BEFORE A COLD FRONT WILL CROSS THE AREA
LATE TUESDAY INTO WEDNESDAY WITH INCREASED CONVECTIVE POTENTIAL ONCE
AGAIN. TEMPS WILL FALL BACK TO SEASONABLE OR SLIGHTLY BELOW AT THE
END OF THE PERIOD.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 18Z...VISIBLE SATELLITE IMAGERY SHOWS WIDESPREAD CIRRUS
FILTERING INTO OUR AREA THIS AFTN. VFR WILL PREVAIL TODAY WITH
FEW/SCT CU AND SCT/BKN CIRRUS ACROSS THE CWA. AN UPPER DISTURBANCE
IS APPROACHING FROM THE NORTH...BUT THE LATEST HRRR RUNS INDICATE
THE SHOWERS ASSOCIATED WITH IT SHOULD REMAIN TO OUR NORTH AND EAST.
WILL STILL MENTION VCSH FOR KILM/KLBT AFTER 00Z...BUT PCPN CHANCES
APPEAR MARGINAL ATTM. INCREASING BOUNDARY LAYER WINDS AND MID-LEVEL
CLOUDINESS WILL INHIBIT FOG FORMATION OVERNIGHT. A COLD FRONT WILL
SAG SOUTHWARD TOWARD THE CAROLINAS ON THURSDAY. SCATTERED SHOWERS
AND T-STORMS ARE EXPECTED AHEAD OF THE BOUNDARY...AND SO HAVE ADDED
VCSH BEGINNING AROUND 14-15Z. T-STORMS WILL LIKELY BE MORE PREVALENT
AFTER THE VALID PERIOD...SO DID NOT MENTION THUNDER IN THESE TAFS.
EXTENDED OUTLOOK...EARLY MORNING FOG POSSIBLE FRIDAY AND SATURDAY.
ISOLATED TSRA SUNDAY AND MONDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM WEDNESDAY...SOUTHWEST FLOW WILL CONTINUE BETWEEN TROUGH
INLAND AND WEAK HIGH PRESSURE OFF SHORE. PERTURBATIONS RIDING
AROUND THE MID TO UPPER RIDGE LOCATED OVER THE CENTRAL CONUS WILL
ACT TO SHARPEN THE TROUGH A BIT OVERNIGHT PRODUCING A SLIGHT RISE IN
WINDS. THE SEA BREEZE THIS AFTERNOON HAS HELPED TO PRODUCE A
GREATER ON SHORE AND SOUTHERLY PUSH WHICH WILL HELP TO PUSH SEAS UP
TO 3 TO 4 FT BY LATE DAY. WINDS WILL VEER TO MORE W-SW TOWARD
MORNING AND THEREFORE EXPECT SEAS THEM TO REMAIN HIGHER OFF
SHORE...WHILE THE NEAR SHORE DROPS SLIGHTLY. OVERALL EXPECT SEAS
TO REMAIN BETWEEN 2 AND 4 FT.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 3 PM WEDNESDAY...WEAK LOW PRESSURE NEAR THE OUTER BANKS WILL
MOVE OFFSHORE THURSDAY AFTERNOON...ALLOWING A COLD FRONT TO SINK
SOUTH ACROSS THE AREA DURING THE EVENING AND OVERNIGHT HOURS. THIS
FRONT SHOULD BE ACCOMPANIED BY SCATTERED SHOWERS AND THUNDERSTORMS
WHICH WILL FOLLOW THE FRONT SOUTH INTO CENTRAL AND SOUTHERN SOUTH
CAROLINA FOR FRIDAY. THE FRONT WILL BEGIN TO RETURN NORTH LATER
THIS WEEKEND.
MODERATE SOUTHWEST WINDS AHEAD OF THE FRONT THURSDAY COULD EXCEED
15 KNOTS...PARTICULARLY DURING THE MORNING HOURS. THESE WINDS WILL
PRODUCE SEAS RANGING AS HIGH AS 3 FT NEARSHORE ALONG THE BRUNSWICK
COUNTY COASTLINE...AND PERHAPS 4 FT OFFSHORE NEAR FRYING PAN
SHOALS. WINDS WILL WEAKEN AND VEER NEAR THE FRONT...THEN SHOULD
INCREASE TO NEAR 15 KNOTS AGAIN FROM THE NORTHEAST ON FRIDAY.
WEAKER ONSHORE WINDS ARE EXPECTED FRIDAY NIGHT.
LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 3 PM WEDNESDAY...HIGH PRESSURE OFFSHORE WILL GRADUALLY SHIFT
FURTHER EAST...ALLOWING FOR WINDS TO TURN FROM THE SE TO THE SW ON
SATURDAY. AS THIS OCCURS...A COLD FRONT WILL SLOWLY APPROACH FROM
THE NW...PINCHING THE GRADIENT AND CAUSING WINDS TO INCREASE
STEADILY FROM THE SW...BECOMING 15-20 KTS AHEAD OF THE FRONT ON
MONDAY. WHILE SATURDAY SEAS WILL BE AROUND 2 FT WITH A WEAK
SOUTHERLY WIND CHOP AND SE GROUND SWELL...THE SPECTRUM WILL BECOME
INCREASINGLY WIND-WAVE DOMINATED...BECOMING 3-5 FT ON MONDAY...AND A
SCEC MAY BE NECESSARY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TRA
NEAR TERM...RGZ
SHORT TERM...TRA
LONG TERM...JDW
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
159 PM EDT WED AUG 28 2013
.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO WEAKEN AS A COLD FRONT APPROACHES
FROM THE NORTH...BRINGING AN INCREASING CHANCE OF SHOWERS AND
THUNDERSTORMS THROUGH THURSDAY NIGHT. HIGH PRESSURE WILL BUILD
SOUTHEAST INTO THE REGION THIS WEEKEND AND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM WEDNESDAY...WARMER AND MORE MOIST AIRMASS IN PLACE
TODAY. TEMPS BETWEEN 85 AND 90 MOST PLACES WITH DEWPOINT TEMPS
AROUND 70 IN A SW FLOW BETWEEN TROUGH OF LOW PRESSURE INLAND AND WEAK
HIGH PRESSURE OFF SHORE. MID TO HIGH CLOUDS WILL CONTINUE TO
STREAM DOWN INTO THE CAROLINAS FROM ASSOCIATED CONVECTION/PCP
UPSTREAM ROUNDING THE TOP OF THE MID TO UPPER RIDGE. THESE CLOUDS
WILL SPREAD SOUTH FILTERING OUT THE SUN AND PRODUCING MOSTLY
CLOUDY SKIES THIS AFTERNOON...ESPECIALLY ACROSS NORTHERN TIER
COUNTIES. THIS WILL ACT TO SLOW DOWN HEATING IN PLACES AND PRODUCE
SLIGHTLY LOWER TEMPS...BUT AS OF NOW...EXPECTING TEMPS TO REACH
BETWEEN 85 AND 90 AIDED BY A WARMER DOWNSLOPE WESTERLY FLOW
THROUGH THE LOW LEVELS.
WITH A PREVAILING SOUTHWEST FLOW AT THE SURFACE...SEA BREEZE SHOULD
PENETRATE FARTHER INLAND OVER NORTH CAROLINA COUNTIES. MOISTURE
RICH AIR WILL PUSH INLAND BEHIND SEA BREEZE WITH GREATEST RISE IN
DEWPOINTS UP CLOSE TO 75 ACROSS NORTH CAROLINA COASTAL
COUNTIES...WHERE MODELS SHOW HIGHEST CAPE VALUES. DEWPOINT TEMPS
INLAND WILL DECREASE REMAINING BELOW 70 IN MOST PLACES. DECENT
SUBSIDENCE INVERSION ALOFT WILL KEEP MOST CONVECTIVE ACTIVITY AT
BAY THIS AFTERNOON...BUT CONVERGENCE ALONG SEA BREEZE COULD TRIGGER
ISLD SHWRS/TSTMS...MAINLY OVER NC COASTAL COUNTIES. ANOTHER FOCUS
OF CONVECTION WILL BE ALONG TROUGH INLAND...MAINLY WEST OF LOCAL
CWA...BUT CLOUDS STREAMING IN FROM THE NORTH WILL CONTINUE TO
INHIBIT THIS ACTIVITY. WILL KEEP WITH MAINLY ISOLATED FOR THIS
AFTERNOON AS SOME PCP COULD SHIFT INTO OUR NORTHWESTERN COUNTIES.
A LINGERING AREA OF MAINLY STRATIFORM PCP WILL ALSO TRACK MAINLY
ACROSS NORTH CAROLINA PRODUCING MAINLY LIGHTER PCP.
MID-LEVEL PERTURBATIONS WILL RIDE AROUND THE MID TO UPPER RIDGE
AS IT SHIFTS WEST PRODUCING A MORE DIRECT STEERING FLOW INTO OUR
AREA. AT THE MOMENT...WATER VAPOR SATELLITE IMAGERY SHOWING
ASSOCIATED CONVECTION WELL UPSTREAM OVER WEST VA/VA BORDER AND
FURTHER NORTH LINING UP NICELY WITH THESE SHORTWAVES. AS THESE
PERTURBATIONS MOVES SOUTH OVER NORTH CAROLINA THEY SHOULD ACT TO
INITIATE SOME CONVECTION...MAINLY NORTH BUT THEY MAY MOVE CLOSE
ENOUGH TO HELP ENHANCE ACTIVITY ALONG THE SEA BREEZE AND INLAND
TROUGH LATER TODAY.
PRECIPITABLE WATER VALUES WILL CONTINUE TO INCREASE REACHING JUST
OVER 2 INCHES THROUGH LATE DAY INTO TONIGHT....BUT THE MID LEVELS
REMAIN FAIRLY DRY AND LIFT WILL REMAIN RATHER WEAK THROUGH THIS
PERIOD. A DECENT CAP WILL REMAIN OVER THE AREA THROUGH THE DAY.
THEREFORE WILL CONTINUE TO INCLUDE ONLY ISOLATED TO LOW END SCT POPS
ACROSS MAINLY NORTH CAROLINA COUNTIES LATE DAY AND TONIGHT. CLOUDS
AND PCP OVERNIGHT WILL KEEP LOWS ABOVE NORMAL...LOWER TO MID 70S.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 3 AM WEDNESDAY...COLD FRONT WILL MOVE INTO THE REGION THEN
STALL EARLY THU. WEAK PATTERN ALOFT WILL KEEP THE FRONT STALLED IN
THE AREA THROUGH THE END OF THE PERIOD. BERMUDA HIGH AND WEAK
SURFACE HIGH BUILDING SOUTH FROM THE GREAT LAKES WILL STRUGGLE FOR
CONTROL FOR MUCH OF THE PERIOD. ON THU THE FRONT AND WEAK
SHORTWAVE IN NORTH-NORTHWEST FLOW ALOFT WILL TRY AND GENERATE
SOME AFTERNOON PRECIP. THE ONE CATCH IS THE SUBSIDENCE BEHIND THE
STRONGER EXITING SHORTWAVE. THIS COULD HINDER POP ALONG THE NC
COAST...ESPECIALLY DURING EARLY AFTERNOON THU. WITH THAT SAID WILL
MAINTAIN CHC POP AS THERE IS PLENTY OF MOISTURE...PRECIPITABLE
WATER VALUES ARE OVER 2 INCHES THU...AND DIURNAL INSTABILITY ALONG
WITH THE WEAK CONVERGENCE ALONG THE SURFACE BOUNDARY.
00Z DATA SUGGESTS THE GREAT LAKES HIGH WILL GAIN A LITTLE BIT OF
A FOOTHOLD FRI...DECREASING PRECIP CHANCES IN THE AFTERNOON AS
DRIER AIR MOVES IN FROM THE NORTH. HOWEVER...THE HIGHS GRASP WILL
BE TENUOUS AT BEST AT IT WOULD NOT TAKE MUCH TO KEEP THE DEEPER
MOISTURE...AND THUS HIGHER POP...OVER THE FORECAST AREA. SINCE
PREVIOUS FORECAST IS IN AGREEMENT WITH THE MOST CURRENT SOLUTION
WILL CONTINUE THE LOW POP FORECAST FOR FRI WITH SOUTHERN COUNTIES
LIKELY TO HAVE THE BEST SHOT AT STORMS.
TEMPERATURES ABOVE CLIMO THU DROP BACK TO CLIMO FRI(THIS ASSUMES THE
FRONT DOES INDEED PUSH SOUTH OF THE AREA). LOW TEMPERATURES WILL
REMAIN A FEW DEGREES ABOVE CLIMO...HELD UP BY BOUNDARY LAYER
MIXING...LINGERING CLOUD COVER AND LOW LEVEL MOISTURE.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 3 AM WEDNESDAY...PERIOD WILL GENERALLY BE DOMINATED BY DEEP
WEST TO NORTHWEST FLOW AS RIDGING REMAINS IN PLACE OVER THE WESTERN
STATES AND TROUGHING DEVELOPS ALONG THE EAST COAST. INITIALLY WEST
FLOW WILL BE WEAK WITH LITTLE IN THE WAY OF DISTURBANCES ALOFT AND A
FRONT STALLED IN THE AREA. THIS CHANGES MON INTO TUE AS A SHORTWAVE
DROPS SOUTHEAST FROM THE UPPER MID-WEST AND PUSHES A COLD FRONT INTO
THE AREA FOR THE END OF THE PERIOD. AHEAD OF THE FRONT WEAK PIEDMONT
TROUGH AND BERMUDA HIGH SETUP AS THE REMAINS OF THE STALLED FRONT
LIFT NORTH. THE RESULT WILL BE A TYPICAL SUMMER PATTERN ACROSS THE
SOUTHEAST FOR THE WEEKEND. LIMITED SUPPORT ALOFT INTO THE START OF
NEXT WEEK WILL KEEP POP IN THE SLIGHT CHC TO LOW CHC RANGE...WHICH
IS MORE OR LESS CLIMO. FOR THE END OF THE PERIOD AN UPTICK IN POP IS
LIKELY AS THE SHORTWAVE/FRONT COMBO MOVES INTO A WARM/MOIST
ENVIRONMENT. WILL BUMP UP INHERITED POP MON/TUE BUT STILL IN CHC
CATEGORY.
TEMPERATURES WILL STEADILY CLIMB DURING THE PERIOD WITH HIGH PUSHING
INTO THE MID 90S BY THE END OF THE PERIOD. LATEST GFS/ECMWF 850
TEMPS SUGGEST TEMPS APPROACHING UPPER 90S WILL BE POSSIBLE ACROSS
INLAND SC MON. LOWS WILL REMAIN ABOVE CLIMO THROUGH THE
PERIOD...GENERALLY LOWER 70S.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 18Z...VISIBLE SATELLITE IMAGERY SHOWS WIDESPREAD CIRRUS
FILTERING INTO OUR AREA THIS AFTN. VFR WILL PREVAIL TODAY WITH
FEW/SCT CU AND SCT/BKN CIRRUS ACROSS THE CWA. AN UPPER DISTURBANCE
IS APPROACHING FROM THE NORTH...BUT THE LATEST HRRR RUNS INDICATE
THE SHOWERS ASSOCIATED WITH IT SHOULD REMAIN TO OUR NORTH AND EAST.
WILL STILL MENTION VCSH FOR KILM/KLBT AFTER 00Z...BUT PCPN CHANCES
APPEAR MARGINAL ATTM. INCREASING BOUNDARY LAYER WINDS AND MID-LEVEL
CLOUDINESS WILL INHIBIT FOG FORMATION OVERNIGHT. A COLD FRONT WILL
SAG SOUTHWARD TOWARD THE CAROLINAS ON THURSDAY. SCATTERED SHOWERS
AND T-STORMS ARE EXPECTED AHEAD OF THE BOUNDARY...AND SO HAVE ADDED
VCSH BEGINNING AROUND 14-15Z. T-STORMS WILL LIKELY BE MORE PREVALENT
AFTER THE VALID PERIOD...SO DID NOT MENTION THUNDER IN THESE TAFS.
EXTENDED OUTLOOK...EARLY MORNING FOG POSSIBLE FRIDAY AND SATURDAY.
ISOLATED TSRA SUNDAY AND MONDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM WEDNESDAY...SOUTHWEST FLOW WILL CONTINUE BETWEEN TROUGH
INLAND AND WEAK HIGH PRESSURE OFF SHORE. PERTURBATIONS RIDING
AROUND THE MID TO UPPER RIDGE LOCATED OVER THE CENTRAL CONUS WILL
ACT TO SHARPEN THE TROUGH A BIT OVERNIGHT PRODUCING A SLIGHT RISE IN
WINDS. THE SEA BREEZE THIS AFTERNOON HAS HELPED TO PRODUCE A
GREATER ON SHORE AND SOUTHERLY PUSH WHICH WILL HELP TO PUSH SEAS UP
TO 3 TO 4 FT BY LATE DAY. WINDS WILL VEER TO MORE W-SW TOWARD
MORNING AND THEREFORE EXPECT SEAS THEM TO REMAIN HIGHER OFF
SHORE...WHILE THE NEAR SHORE DROPS SLIGHTLY. OVERALL EXPECT SEAS
TO REMAIN BETWEEN 2 AND 4 FT.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 3 AM WEDNESDAY...SOUTHWEST FLOW AHEAD OF A SLOW MOVING COLD
FRONT THU WILL BECOME LIGHT AND VARIABLE THU NIGHT INTO FRI.
EVENTUALLY LIGHT NORTH TO NORTHEAST FLOW WILL DEVELOP DURING FRI AS
THE FRONT PUSHES FARTHER SOUTH OF THE WATERS. HIGH BUILDING IN
BEHIND THE FRONT IS ON THE WEAK SIDE AND LITTLE CHANGE TO THE
GRADIENT IS EXPECTED. SPEEDS START OUT 10 TO 15 KT BUT ONCE THE
FRONT PASSES SPEEDS WILL BE CLOSER TO 10 KT. SEAS 2 TO 4 FT THU
WILL SUBSIDE TO 2 TO 3 FT FRI.
LONG TERM /SATURDAY THROUGH SUNDAY/...
AS OF 3 AM WEDNESDAY...LIGHT AND VARIABLE FLOW AT THE START OF THE
PERIOD WILL QUICKLY BECOME SOUTH TO SOUTHWEST AS FRONTAL REMAINS
LIFT NORTH AND BERMUDA HIGH BUILDS BACK OVER THE WATERS. GRADIENT
WILL BE WEAK AT FIRST WITH SPEEDS 10 KT OR LESS INTO SAT NIGHT.
DISTANT COLD FRONT WILL LEAD TO A SLIGHT PINCHING OF THE GRADIENT
SUN...INCREASING SPEEDS TO 10 TO 15 KT SUN AND SUN NIGHT. SEAS WILL
RUN 2 TO 3 FT THROUGH THE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...RGZ
SHORT TERM...III
LONG TERM...III
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1000 AM EDT WED AUG 28 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE REGION FROM THE
NORTHWEST TODAY. A COLD FRONT WILL FOLLOW ON THURSDAY BEFORE WEAK
HIGH PRESSURE RETURNS FOR THE END OF THE WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 AM WEDNESDAY...
CURRENT SATELLITE AND RADAR TRENDS INDICATE THAT THE UPPER LEVEL LOW
MOVING THROUGH VA IS AHEAD OF SCHEDULE AND WILL BE APPROACHING THE
AREA BY 15Z FROM THE NORTH. CURRENT DEVELOPMENT ON THE SOUTHWESTERN
EDGE OF THE DISTURBANCE COUPLED WITH RAP FORECASTED ML CAPE SUGGESTS
THAT THE TRIAD AND THE CENTRAL NORTHERN COUNTIES ALONG THE VA BORDER
WOULD BE THE FIRST INFLUENCED BY THIS SYSTEM. CURRENT RUN OF THE
HRRR SHOWS A SHOWERY SCENARIO WITH SOME EMBEDDED CELLS PUSHING
THROUGH THE CWA THROUGHOUT THE AFTERNOON AND INTO THE EARLY EVENING
HOURS WITH SOME BROKEN LINES TRAILING THE MAIN SHIELD OF
PRECIPITATION LATER THIS AFTERNOON. STILL EXPECTING LESS THAN A
QUARTER OF AN INCH OF QPF WIDESPREAD THIS AFTERNOON WITH LOCALIZED
AREAS RECEIVING MORE IN HEAVIER SHOWERS. RAP SOUNDINGS IN BUFKIT ARE
NOT TERRIBLY IMPRESSIVE AS FAR AS INSTABILITY GOES WITH 500-1000
J/KG OF ELEVATED INSTABILITY ABOVE 800 MB OR SO. BULK SHEAR VALUES
OF 20-30 KTS INDICATE THAT MULTICELLS ARE MOST LIKELY...SUPPORTED BY
THE BROKEN LINES SHOWING UP IN THE CAMS. WET INVERTED V SIGNATURES
DO SUGGEST THAT DAMAGING WINDS MAY BE POSSIBLE...ESPECIALLY IN MORE
ORGANIZED CONVECTION. NOT ANTICIPATING TOO MUCH SEVERE WEATHER BUT A
COUPLE OF WARNINGS ARE POSSIBLE. CURRENT SPC OUTLOOK PUTS US IN IN A
SEE TEXT FOR TODAY WITH MINIMAL MENTION OF SEVERE WEATHER.
FAIRLY DENSE OVERCAST SKIES OVERSPREADING THE CWA FROM THE NORTH
WILL ENDANGER THE ORIGINALLY FORECASTED HIGH TEMPERATURES FOR TODAY
SOUTHWESTERN PORTIONS OF THE CWA COULD BE SPARED A FOR A WHILE
LONGER BUT THE LIKELY SCENARIO FOR HIGHS TODAY WILL BE LOWER TO MID
80S ACROSS MUCH OF THE CWA WITH A FEW ISOLATED UPPER 80S IN THE
SOUTHERN TIER OF COUNTIES. FAIRLY MOIST ATMOSPHERE OVERNIGHT WILL
KEEP LOW TEMPERATURES UP IN THE LOWER 70S ACROSS MUCH OF THE AREA.
&&
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 305 AM WEDNESDAY...
BOTH THE NAM AND THE GFS FORECAST A 700MB SHORTWAVE MOVING THROUGH
CENTRAL NORTH CAROLINA DURING THE DAY ALONG WITH THE COLD FRONT. THE
FRONT SLOWLY SETTLES SOUTH AND SHOULD BE JUST SOUTH OF THE AREA BY
00Z...CONTINUING ITS SLOW PROGRESS SOUTH FROM THERE. THE AIR MASS
REMAINS MOIST ALONG AND BEHIND THE FRONT...BUT BUFR SOUNDINGS FROM
THE NAM AND GFS ARE NOT PARTICULARLY UNSTABLE AND SHOW SOME WARMING
ALOFT AROUND AND JUST ABOVE 700MB. IN A RELATIVE SENSE...THE BETTER
INSTABILITY IS SOUTH OF U.S. 64...AND FOR THIS FORECAST WILL
CONTINUE THE TREND OF A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS
NORTH...CHANCE OVER THE SANDHILLS AND SOUTHERN COASTAL PLAIN WHERE
THE 850MB LIFT IS GREATER THURSDAY DURING THE DAY...DIMINISHING FROM
NORTH-TO-SOUTH LATE IN THE DAY AND IN THE EVENING AS PRECIPITABLE
WATER VALUES FALL FROM NEAR TWO INCHES EARLY THURSDAY TO AT OR BELOW
1.5 INCHES BY 12Z FRIDAY. HIGHER CONFIDENCE IS IN THE DEVELOPMENT OF
AREAS OF CU/SC IN THE MOIST LOW-LEVEL AIR MASS JUST BEHIND THE
FRONT...GIVEN THE DECENT MOISTURE ON THE GFS BUFR SOUNDINGS AND THE
CANADIAN CLOUD COVER MODEL SHOWING NUMEROUS AREAS OF SUCH CLOUDS IN
THE NORTHEAST FLOW BEHIND THE FRONT. LOW-LEVEL RH FORECAST BY THE
NAM AND GFS IS FAIRLY HIGH AS WELL.
OVERNIGHT THURSDAY...THE GFS AND NAM FORECAST THE MID AND UPPER
LEVELS DRYING...WHILE LOW-LEVEL MOISTURE REMAINS WITH DEW POINTS
FROM THE MID 60S TO AROUND 70. THE NAM...WITH ITS LIGHTER AND MORE
VARIABLE WINDS...SUGGESTS THE DEVELOPMENT OF FOG...WHILE THE GFS
WITH A MORE PERSISTENT NORTHEAST WIND SUGGESTS STRATUS. WILL PLAN TO
NOTE PATCHY FOG IN THE GRIDDED AND WORDED FORECAST FOR NOW LATE
THURSDAY NIGHT INTO EARLY FRIDAY. HIGHS THURSDAY IN THE MID 80S
NORTH TO AROUND 90 SOUTH...AGAIN A LITTLE BELOW WHAT THE 1000-850MB
THICKNESSES WOULD SUGGEST FOR HIGHS. OVERNIGHT LOWS THURSDAY NIGHT
66 TO 71.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 305 AM WEDNESDAY...
THE STRONG UPPER LEVEL RIDGE OVER THE CENTRAL US WILL BEGIN TO
WEAKEN AND RETROGRADE WESTWARD ON FRIDAY...WITH NORTHWESTERLY FLOW
ALOFT PERSISTING OVER NC. MEANWHILE...THE WEAK FRONTAL ZONE
CROSSING THE CWA EARLY THURSDAY WILL SINK SOUTH OF THE AREA AND
EVENTUALLY WASH OUT BY FRIDAY. WITH NORTHWESTERLY FLOW ALOFT...THE
LEE TROUGH WILL STRENGTHEN THROUGH THE WEEKEND...AND RETURN FLOW
WILL BRING PW VALUES BACK UP TO AROUND 2 INCHES. UPPER DISTURBANCES
CURRENTLY MOVING AROUND THE UPPER RIDGE WILL INEVITABLY DIVE
SOUTHEAST ACROSS THE APPALACHIANS...BUT ITS DIFFICULT TO FIND ANY
SIGNIFICANT FEATURES IN MODEL GUIDANCE AT THIS POINT. EXPECT A
MOSTLY DRY DAY FRIDAY...WITH AN INCREASING SLIGHT CHANCE TO CHANCE
POP SATURDAY AND SUNDAY. BY MONDAY...MORE SUBSTANTIAL SHORTWAVE IS
EXPECTED TO MOVE ACROSS THE NORTHERN GREAT LAKES AND EASTERN
CANADA..LEADING TO A DEEPER TROUGH OVER THE EASTERN US. AS THE FLOW
ALOFT BECOMES MORE CYCLONIC AND A COLD FRONT APPROACHES FROM THE
NORTHWEST...CONVECTIVE COVERAGE SHOULD INCREASE MONDAY AND TUESDAY.
IN ADDITION...BOTH THE ECMWF INDICATE THAT THE CYCLONIC CIRCULATION
CURRENTLY OVER SOUTHERN FLORIDA WILL DRIFT SLOWLY INTO THE GULF AND
EVENTUALLY BE DRAWN NORTHEASTWARD ACROSS THE SOUTHEAST AND ABSORBED
BY THE LOWER HEIGHTS OVER THE EASTERN US. HOWEVER...THE IMPACTS OF
THIS FEATURE ARE LESS CERTAIN AT THIS TIME. WITH THICKNESSES
HOLDING RELATIVELY STEADY THROUGH THE MONDAY.... HIGH TEMPS OVER THE
WEEKEND WILL REBOUND TO AT OR JUST ABOVE NORMAL IN THE UPPER 80S TO
AROUND 90. LOWS WILL BE IN THE UPPER 60S AND LOWER 70S. SLIGHTLY
COOLER CONDITIONS ARE THEN POSSIBLE BY THE MIDDLE OF NEXT WEEK AS
THE PATTERN BECOMES DOMINATED BY THE STRONGER TROUGH MENTION ABOVE.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AS OF 650 AM WEDNESDAY...
BETWEEN SCATTERED TO NUMEROUS AREAS OF MID- AND HIGH-LEVEL CLOUDS
EARLY THIS MORNING THERE WILL BE AREAS OF MVFR CONDITIONS IN FOG.
VERY LOCALLY IFR CONDITIONS WILL OCCUR...BUT THE DOMINANT SUB-VFR
CATEGORY SHOULD BE MVFR DUE TO THE PRESENCE OF THE HIGHER CLOUDS.
VFR CONDITIONS WILL PREVAIL THEN THROUGH THE REST OF THE 12Z VALID
TAF PERIOD OUTSIDE OF ANY SHOWERS OR THUNDERSTORMS. CURRENTLY IT
APPEARS THE BEST POTENTIAL FOR STORMS WILL OCCUR THIS AFTERNOON FROM
THE TRIANGLE NORTHEAST ESPECIALLY TOWARD KRWI...WHERE STORMS MAY
BECOME MORE NUMEROUS DURING THE AFTERNOON. SCATTERED SHOWERS AND
THUNDERSTORMS ARE EXPECTED THIS EVENING. WITH THE RELATIVELY DRY AIR
BELOW MOISTURE ALOFT...ANY STRONG STORM COULD PRODUCE A STRONG WIND
GUST.
BEYOND THE 12Z VALID TAF PERIOD...VFR CONDITIONS ARE EXPECTED
THURSDAY INTO THURSDAY NIGHT...OUTSIDE OF ANY ISOLATED-TO-SCATTERED
SHOWER OR THUNDERSTORM. BOTH THE GFS AND NAM MODEL GUIDANCE ARE
CONFIDENTLY HINTING AT THE POTENTIAL FOR AREAS OF IFR CONDITIONS
LATE THURSDAY NIGHT INTO FRIDAY MORNING BEHIND THE COLD FRONT IN
EITHER LOW CLOUDS OR FOG. LOW CLOUDS AND/OR FOG WILL MIX OUT FRIDAY
LEAVING BEHIND VFR-LEVEL CUMULUS DURING THE DAY. SATURDAY INTO
SUNDAY...VFR CONDITIONS WILL PREVAIL WITH AREAS OF EARLY MORNING FOG
OR LOW CLOUDS POSSIBLE EACH DAY...ALONG WITH ISOLATED-TO-SCATTERED
AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ELLIS
NEAR TERM...ELLIS
SHORT TERM...DJF
LONG TERM...BLS
AVIATION...DJF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
650 AM EDT WED AUG 28 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE REGION FROM THE
NORTHWEST THIS AFTERNOON AND THIS EVENING. A COLD FRONT FOLLOWS THE
DISTURBANCE AND PASSES THROUGH NORTH CAROLINA THURSDAY. WEAK HIGH
PRESSURE BUILDS INTO THE REGION BEHIND THE FRONT LATE THURSDAY INTO
FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 650 AM WEDNESDAY...
THE PRIMARY WEATHER CONCERN FOR TODAY INTO TONIGHT WILL BE THE
INFLUENCE OF AN UPPER-LEVEL DISTURBANCE MOVING INTO AND THROUGH
CENTRAL NORTH CAROLINA IN THE NORTHWEST FLOW ALOFT. THE UPPER FLOW
IS BROADLY DIFFLUENT ON WATER VAPOR...AND AS THE DISTURBANCE
APPROACHES THIS AFTERNOON...THE CONSENSUS OF THE GUIDANCE INCREASES
LIFT PARTICULARLY OVER THE NORTH PART OF THE AREA BY 19Z. BUFR
SOUNDINGS FROM BOTH THE NAM AND THE GFS ARE NOT PARTICULARLY
UNSTABLE...AND MLCAPE FORECAST BY BOTH MODELS IS IN THE RANGE OF
ABOUT 1000-1500J/KG. DCAPE IS ONLY MODEST AS WELL...FORECAST TO
ABOUT 500J/KG. 0-3KM SHEAR INCREASES...HOWEVER...TO 25 TO 30KT
COINCIDENT WITH THE APPROACH OF THE MID-LEVEL WAVE AND THE GFS
FORECAST OF A WEAK 500MB JETLET TOWARD THE NORTHEAST PIEDMONT AROUND
35KT. IN ADDITION...THE HIGHEST QPF FORECAST BY THE GFS AND THE NAM
TODAY...ALONG WITH THE CONVECTIVE-ALLOWING MODELS FROM WPC AND SPC...
SUGGEST HIGHEST CHANCES AND THE POTENTIAL FOR A PERIOD OF NUMEROUS
SHOWERS AND THUNDERSTORMS OVER THE NORTHEAST PIEDMONT AND NORTHERN
COASTAL PLAIN THIS AFTERNOON FROM ABOUT 20Z TO 00Z. GIVEN THE
RELATIVELY DRY AIR BELOW THE MID-LEVELS ON BUFR SOUNDINGS...ANY
STRONG STORM COULD PRODUCE A STRONG-TO-SEVERE WIND GUST. WILL NOTE A
MENTION OF THIS IN THE HWO FOR THIS AFTERNOON INTO THIS EVENING...
WITH MORE OF A FOCUS NORTHEAST. SOUTH OF U.S. 64 AND ESPECIALLY
ACROSS THE SANDHILLS AND FAR SOUTHERN COASTAL PLAIN...GIVEN THE
GREATER STABILITY AND LACK OF A MAIN SOURCE OF LIFT FOR MUCH OF THE
DAY...PRECIPITATION THERE IS EXPECTED TO BE MORE ISOLATED. DURING
THE EVENING AND OVERNIGHT HOURS...MESOSCALE INFLUENCES DUE TO
OUTFLOW...ALONG WITH A MAXIMUM OF MOISTURE WITH PRECIPITABLE
WATER VALUES AT OR JUST ABOVE TWO INCHES AND DECENT DIFFLUENCE ALOFT
AS FORECAST BY THE GFS...ANTICIPATE OVERALL SCATTERED SHOWERS AND
THUNDERSTORMS BECOMING ISOLATED OVERNIGHT AS BUFR SOUNDINGS
GRADUALLY BECOME MORE STABLE. HIGHS TODAY ARE A LITTLE TRICKY GIVEN
THE MOISTURE UPSTREAM...BUT THINK THERE WILL BE ENOUGH PERIODS OF
SUN THAT HIGHS CLOSE TO THE MOS GUIDANCE SHOULD BE REALIZED IN MOST
LOCATIONS. THE CONSENSUS OF BIAS-CORRECTED GUIDANCE IS ABOUT A
DEGREE OR TWO BELOW MOS...AND WILL LEAN TOWARD A BLEND.
ON THE OTHER HAND...TAKING A LOOK AT THE LATEST RADAR AND SATELLITE
TRENDS...ALONG WITH SOME OF THE HRRR WRF GUIDANCE...CLOUDS AND
PRECIPITATION FROM THE UPSTREAM WAVE MAY MOVE IN FASTER THAN EARLIER
GUIDANCE SHOWED AND WAS ANTICIPATED. FOR THE EARLY MORNING
UPDATE...LOWERED MAXES ABOUT A DEGREE OR SO NORTH OF U.S. 64 AND
NOTED A CHANCE OF A SHOWER EARLIER ESPECIALLY TOWARD THE VIRGINIA
BORDER. CLOUDS COULD ALSO HAMPER AVAILABLE INSTABILITY. CONFIDENCE
HAS BEEN REDUCED A LITTLE DUE TO THE PROGRESSION OF THE WAVE.
OVERNIGHT LOWS TONIGHT MOSTLY IN THE LOWER 70S.
&&
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 305 AM WEDNESDAY...
BOTH THE NAM AND THE GFS FORECAST A 700MB SHORTWAVE MOVING THROUGH
CENTRAL NORTH CAROLINA DURING THE DAY ALONG WITH THE COLD FRONT. THE
FRONT SLOWLY SETTLES SOUTH AND SHOULD BE JUST SOUTH OF THE AREA BY
00Z...CONTINUING ITS SLOW PROGRESS SOUTH FROM THERE. THE AIR MASS
REMAINS MOIST ALONG AND BEHIND THE FRONT...BUT BUFR SOUNDINGS FROM
THE NAM AND GFS ARE NOT PARTICULARLY UNSTABLE AND SHOW SOME WARMING
ALOFT AROUND AND JUST ABOVE 700MB. IN A RELATIVE SENSE...THE BETTER
INSTABILITY IS SOUTH OF U.S. 64...AND FOR THIS FORECAST WILL
CONTINUE THE TREND OF A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS
NORTH...CHANCE OVER THE SANDHILLS AND SOUTHERN COASTAL PLAIN WHERE
THE 850MB LIFT IS GREATER THURSDAY DURING THE DAY...DIMINISHING FROM
NORTH-TO-SOUTH LATE IN THE DAY AND IN THE EVENING AS PRECIPITABLE
WATER VALUES FALL FROM NEAR TWO INCHES EARLY THURSDAY TO AT OR BELOW
1.5 INCHES BY 12Z FRIDAY. HIGHER CONFIDENCE IS IN THE DEVELOPMENT OF
AREAS OF CU/SC IN THE MOIST LOW-LEVEL AIR MASS JUST BEHIND THE
FRONT...GIVEN THE DECENT MOISTURE ON THE GFS BUFR SOUNDINGS AND THE
CANADIAN CLOUD COVER MODEL SHOWING NUMEROUS AREAS OF SUCH CLOUDS IN
THE NORTHEAST FLOW BEHIND THE FRONT. LOW-LEVEL RH FORECAST BY THE
NAM AND GFS IS FAIRLY HIGH AS WELL.
OVERNIGHT THURSDAY...THE GFS AND NAM FORECAST THE MID AND UPPER
LEVELS DRYING...WHILE LOW-LEVEL MOISTURE REMAINS WITH DEW POINTS
FROM THE MID 60S TO AROUND 70. THE NAM...WITH ITS LIGHTER AND MORE
VARIABLE WINDS...SUGGESTS THE DEVELOPMENT OF FOG...WHILE THE GFS
WITH A MORE PERSISTENT NORTHEAST WIND SUGGESTS STRATUS. WILL PLAN TO
NOTE PATCHY FOG IN THE GRIDDED AND WORDED FORECAST FOR NOW LATE
THURSDAY NIGHT INTO EARLY FRIDAY. HIGHS THURSDAY IN THE MID 80S
NORTH TO AROUND 90 SOUTH...AGAIN A LITTLE BELOW WHAT THE 1000-850MB
THICKNESSES WOULD SUGGEST FOR HIGHS. OVERNIGHT LOWS THURSDAY NIGHT
66 TO 71.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 305 AM WEDNESDAY...
THE STRONG UPPER LEVEL RIDGE OVER THE CENTRAL US WILL BEGIN TO
WEAKEN AND RETROGRADE WESTWARD ON FRIDAY...WITH NORTHWESTERLY FLOW
ALOFT PERSISTING OVER NC. MEANWHILE...THE WEAK FRONTAL ZONE
CROSSING THE CWA EARLY THURSDAY WILL SINK SOUTH OF THE AREA AND
EVENTUALLY WASH OUT BY FRIDAY. WITH NORTHWESTERLY FLOW ALOFT...THE
LEE TROUGH WILL STRENGTHEN THROUGH THE WEEKEND...AND RETURN FLOW
WILL BRING PW VALUES BACK UP TO AROUND 2 INCHES. UPPER DISTURBANCES
CURRENTLY MOVING AROUND THE UPPER RIDGE WILL INEVITABLY DIVE
SOUTHEAST ACROSS THE APPALACHIANS...BUT ITS DIFFICULT TO FIND ANY
SIGNIFICANT FEATURES IN MODEL GUIDANCE AT THIS POINT. EXPECT A
MOSTLY DRY DAY FRIDAY...WITH AN INCREASING SLIGHT CHANCE TO CHANCE
POP SATURDAY AND SUNDAY. BY MONDAY...MORE SUBSTANTIAL SHORTWAVE IS
EXPECTED TO MOVE ACROSS THE NORTHERN GREAT LAKES AND EASTERN
CANADA..LEADING TO A DEEPER TROUGH OVER THE EASTERN US. AS THE FLOW
ALOFT BECOMES MORE CYCLONIC AND A COLD FRONT APPROACHES FROM THE
NORTHWEST...CONVECTIVE COVERAGE SHOULD INCREASE MONDAY AND TUESDAY.
IN ADDITION...BOTH THE ECMWF INDICATE THAT THE CYCLONIC CIRCULATION
CURRENTLY OVER SOUTHERN FLORIDA WILL DRIFT SLOWLY INTO THE GULF AND
EVENTUALLY BE DRAWN NORTHEASTWARD ACROSS THE SOUTHEAST AND ABSORBED
BY THE LOWER HEIGHTS OVER THE EASTERN US. HOWEVER...THE IMPACTS OF
THIS FEATURE ARE LESS CERTAIN AT THIS TIME. WITH THICKNESSES
HOLDING RELATIVELY STEADY THROUGH THE MONDAY.... HIGH TEMPS OVER THE
WEEKEND WILL REBOUND TO AT OR JUST ABOVE NORMAL IN THE UPPER 80S TO
AROUND 90. LOWS WILL BE IN THE UPPER 60S AND LOWER 70S. SLIGHTLY
COOLER CONDITIONS ARE THEN POSSIBLE BY THE MIDDLE OF NEXT WEEK AS
THE PATTERN BECOMES DOMINATED BY THE STRONGER TROUGH MENTION ABOVE.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AS OF 650 AM WEDNESDAY...
BETWEEN SCATTERED TO NUMEROUS AREAS OF MID- AND HIGH-LEVEL CLOUDS
EARLY THIS MORNING THERE WILL BE AREAS OF MVFR CONDITIONS IN FOG.
VERY LOCALLY IFR CONDITIONS WILL OCCUR...BUT THE DOMINANT SUB-VFR
CATEGORY SHOULD BE MVFR DUE TO THE PRESENCE OF THE HIGHER CLOUDS.
VFR CONDITIONS WILL PREVAIL THEN THROUGH THE REST OF THE 12Z VALID
TAF PERIOD OUTSIDE OF ANY SHOWERS OR THUNDERSTORMS. CURRENTLY IT
APPEARS THE BEST POTENTIAL FOR STORMS WILL OCCUR THIS AFTERNOON FROM
THE TRIANGLE NORTHEAST ESPECIALLY TOWARD KRWI...WHERE STORMS MAY
BECOME MORE NUMEROUS DURING THE AFTERNOON. SCATTERED SHOWERS AND
THUNDERSTORMS ARE EXPECTED THIS EVENING. WITH THE RELATIVELY DRY AIR
BELOW MOISTURE ALOFT...ANY STRONG STORM COULD PRODUCE A STRONG WIND
GUST.
BEYOND THE 12Z VALID TAF PERIOD...VFR CONDITIONS ARE EXPECTED
THURSDAY INTO THURSDAY NIGHT...OUTSIDE OF ANY ISOLATED-TO-SCATTERED
SHOWER OR THUNDERSTORM. BOTH THE GFS AND NAM MODEL GUIDANCE ARE
CONFIDENTLY HINTING AT THE POTENTIAL FOR AREAS OF IFR CONDITIONS
LATE THURSDAY NIGHT INTO FRIDAY MORNING BEHIND THE COLD FRONT IN
EITHER LOW CLOUDS OR FOG. LOW CLOUDS AND/OR FOG WILL MIX OUT FRIDAY
LEAVING BEHIND VFR-LEVEL CUMULUS DURING THE DAY. SATURDAY INTO
SUNDAY...VFR CONDITIONS WILL PREVAIL WITH AREAS OF EARLY MORNING FOG
OR LOW CLOUDS POSSIBLE EACH DAY...ALONG WITH ISOLATED-TO-SCATTERED
AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DJF
NEAR TERM...DJF
SHORT TERM...DJF
LONG TERM...BLS
AVIATION...DJF
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1133 PM CDT TUE AUG 27 2013
.DISCUSSION...
Please see the below aviation discussion section.
&&
.AVIATION...
Look for VFR conditions to continue across West Central Texas for
the next 24 hours. Also, I`d plan you surface winds to be light,
mainly from the south around 10 knots or less.
Huber
&&
.PREV DISCUSSION... /ISSUED 629 PM CDT TUE AUG 27 2013/
DISCUSSION...
See aviation discussion below.
AVIATION...
VFR conditions will prevail the next 24 hours. With the tropical
moisture in place lowered clouds will move into the area early
morning, before sunrise. Model soundings suggest cigs should stay
above 3000 ft. NAM MOS, especially at Brady, is suggesting cigs
could go lower, but at this point I do not have the confidence to go
MVFR. After sunrise, cigs should begin to burn off by mid morning.
Winds will be light and mostly out of the south to southeast through
the TAF period.
PREV DISCUSSION... /ISSUED 340 PM CDT TUE AUG 27 2013/
SHORT TERM...(Tonight and Wednesday)
Isolated shower activity will be ending this evening, as an easterly
wave moves northwest. HRRR model seems to have been the better
model, indicating rapid weakening showers this afternoon. The NAM
and GFS models had more extensive coverage this afternoon over the
Big Country and Concho Valley. In any case...all models show
precipitation ending by early evening with loss of the suns heating.
Some patchy stratus possible late tonight and early Wednesday
morning...due to moist vegetation and light winds. Temperatures
rebound into the lower and mid 90s Wednesday with dry conditions and
and mostly sunny skies.
LONG TERM...(Thursday through Tuesday)
Dry and hot weather to prevail through the weekend.
The ECMWF and the GFS are still in good agreement, indicating that
once the wave moves out of the area tomorrow, the upper level high
pressure will settle back into the area. With the high dominating
the weather across the southern plains, looks like dry conditions
will prevail. The center of the high pressure will shift from the
mid Mississippi Valley on Wednesday, to Texas on Thursday, and into
the southern Rockies for the weekend. Since we don`t see the center
of the high sit directly over West Central Texas, temperatures are
more likely to be in the mid and upper 90s to near 100 rather than
something much warmer. But in any case, dry and warmer than normal
conditions will be the rule.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 71 95 71 97 72 / 10 5 5 5 5
San Angelo 70 93 70 96 71 / 10 5 5 5 5
Junction 70 93 70 95 70 / 10 5 5 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
Reimer/Huber
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
848 PM EDT THU AUG 29 2013
.SYNOPSIS...
A FRONTAL BOUNDARY ACROSS THE CAROLINAS WILL CONTINUE TO SHIFT
SOUTH AND WEAKEN OVERNIGHT AS WEAK HIGH PRESSURE BUILDS IN FROM
THE NORTH INTO FRIDAY. THE HIGH SLIDES OFFSHORE BY SATURDAY
ALLOWING A RETURN FLOW OF MOISTURE TO DEVELOP ALONG WITH A
PASSING WARM FRONT OVER THE WEEKEND. A STRONG COLD FRONT WILL
ARRIVE EARLY NEXT WEEK WITH ANOTHER ROUND OF SHOWERS AND STORMS
FOLLOWED BY COOLER HIGH PRESSURE FOR THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH FRIDAY/...
AS OF 830 PM EDT THURSDAY...
HAVE AGAIN UPPED POPS IN A SMALL STRIP ACROSS THE WEST WHERE A
PERSISTENT BAND OF SCATTERED SHRA/TSRA PRODUCING VERY HEAVY
RAINFALL LINGERS. THIS ALONG A WEAK LOW LEVEL CONVERGENCE/THETA-E
AXIS NEAR THE EASTERN SLOPES OF THE APPALACHIANS WHERE AIDED BY
LOW LEVEL EASTERLY FLOW PER EVENING RAOBS AND JUST ENOUGH
INSTABILITY GIVEN ML CAPES OF AROUND 1K J/KG. WITH PWATS ALSO JUST
BELOW 2 INCHES THIS EVENING...STORMS HAVE BEEN QUITE EFFICIENT
HEAVY RAIN PRODUCERS WITH MOSTLY LOW TOPPED CONVECTION UNDER THE
DRIER AIR ALOFT SEEN OFF CURRENT SOUNDINGS. LATEST HRRR WHICH HAS
BEEN ON TRACK SINCE LATE THIS AFTERNOON...GRADUALLY CHASES THIS
CONVERGENCE ZONE SW INTO FAR SW VA AND NW NC OVER THE NEXT HOUR OR
TWO BEFORE FINALLY PUSHING IT OUT OF THE REGION AROUND MIDNIGHT.
THEREFORE WILL KEEP SOME SPOTS OF HIGHER LIKELY POPS GOING WEST
WITH SURROUNDING LOW CHANCES WEST OF THE BLUE RIDGE AND BASICALLY
DRY ELSW OVERNIGHT.
BEEFED UP FOG COVERAGE ESPCLY WHERE HEAVY RAIN HAS ALREADY
OCCURRED OR MAY SPREAD INTO SHORTLY AND KEPT PATCHY MENTION MOST
OTHER SPOTS GIVEN SUCH MOIST CONDITIONS. LOW TEMPS MAY STRUGGLE TO
REACH GOING LOWS ALTHOUGH APPEARS MORE CLEARING AND SOME DROPOFF
IN DEWPOINTS LATE MAY ALLOW ALL TO FALL INTO THE 60S.
EMBEDDED IN THE NORTHWEST FLOW FRIDAY WILL BE ANOTHER S/W TROUGH
PROGGED OVER THE AREA FRIDAY AFTERNOON. SCATTERED SHOWERS AND
THUNDERSTORMS MAY DEVELOP ACROSS EXTREME SW VA AND NW NC. SFC HIGH
PRESSURE MEANWHILE CONTINUES TO SLIDE EASTWARD...BECOMING CENTERED
OVER THE MID-ATLANTIC SEABOARD BY FRI AFTERNOON WITH RESULTANT
SOUTHEASTERLY SFC FLOW. PLAYED HIGH TEMPERATURES CLOSE TO ADJMAVBC
WITH READINGS FROM THE UPPER 70S IN THE MOUNTAINS TO THE MID 80S IN
THE PIEDMONT.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
AS OF 235 PM EDT THURSDAY...
SURFACE HIGH PRESSURE BEGINS TO PULL OFF THE MID ATLANTIC SHORE
ALLOWING A WARM FRONT TO PASS OVER THE REGION FRIDAY NIGHT INTO
SATURDAY. A MID LEVEL SHORT WAVE...A SURFACE LEE TROUGH...AND
AFTERNOON HEATING...WILL BRING SCATTERED SHOWERS AND THUNDERSTORMS
TO THE MOUNTAINS BY MID SATURDAY AFTERNOON...THEN SPREADS TO THE
FOOTHILLS AND PIEDMONT DURING THE LATE AFTERNOON AND EARLY
EVENING. THESE STORMS WILL WANE WITH LOSE OF HEATING AND AS THE
SHORT WAVE TRACKS TO THE VA COAST SATURDAY EVENING.
WITH THE PASSING OF THE WARM FRONT...WARM AND HUMID CONDITIONS
WILL GRACE THE REGION THROUGH THE PERIOD AND INTO EARLY NEXT WEEK.
SATURDAY HIGH TEMPERATURES WILL RUN IN THE 80S WITH DEW POINTS IN
THE MID TO UPPER 60S.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 246 PM EDT THURSDAY...
A COLD FRONT WILL TRACK ACROSS THE UPPER MISSISSIPPI VALLEY ON
SUNDAY. THIS FAST MOVING FRONT WILL COME ACROSS THE SOUTH-CENTRAL
APPALACHIANS MONDAY AND MONDAY NIGHT. BY TUESDAY...THIS FRONT WILL
BE ALONG THE EAST COAST. PREFRONTAL SHOWERS AND THUNDERSTORMS ARE
EXPECTED SUNDAY AFTERNOON AND MAY LINGER DEEP INTO SUNDAY NIGHT. A
DECENT LOOKING SHORT WAVE...TRACKING ALONG THE FRONT...WILL BRING
A CHANCE FOR STRONG TO SEVERE STORMS INTO THE AREA MONDAY
AFTERNOON AND EVENING. HEAVY RAIN MAY ALSO ACCOMPANY STORMS SUNDAY
AND MONDAY...BUT SHOULD BE MOVING ENOUGH NOT TO CAUSE AND
SIGNIFICANT FLOOD PROBLEMS. ONCE THE FRONT CLEARS THE AREA MONDAY
NIGHT...HIGH PRESSURE WILL BUILD INTO THE REGION FOR THE REMAINDER
OF THE WORK WEEK.
SUMMER MAKES A RETURN TO THE REGION WITH WARMER THAN NORMAL
TEMPERATURES SUNDAY AND MONDAY. TEMPERATURES EACH AFTERNOON WILL
BE IN THE 80S WITH LOWER 90S POSSIBLE TOWARD SOUTHSIDE VA.
FOLLOWING THE FRONTAL PASSAGE...TEMPERATURES WILL RUN COOLER THAN
NORMAL...MID 70S IN THE WEST TO LOWER 80S IN THE EAST.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
AS OF 700 PM EDT THURSDAY...
SURFACE FRONT HAS SHIFTED SOUTH OF THE AREA LEAVING A DEEP
BUT WEAK NORTHERLY FLOW ACROSS THE REGION THIS EVENING. HOWVER
LOW LEVEL CONVERGENCE ALONG THE EASTERN SLOPES OF THE
APPALACHIANS IN CONJUNCTION WITH WEAK INSTABILITY CONTINUES TO
KEEP A NARROW BAND OF DEEPER CONVECTION ONGOING ATTM. THIS BAND OF
HEAVIER SHRA/TSRA LOOKS TO LINGER ANOTHER COUPLE OF HOURS SO
INCLUDED MVFR/IFR AT KLWB AND VCSH AT KBCB ALONG THIS AXIS OF
PRECIP. ELSW LEAVING OUT ANY SHRA MENTION AS APPEARS LOSS OF
HEATING ALONG WITH LACK OF ANY UPPER LEVEL SUPPORT SHOULD NOT
ALLOW COVERAGE TO EXPAND MUCH MORE BEFORE FADING.
OTRW HIGH PRESSURE BEHIND THE FRONT MOVES IN LATER THIS EVENING
AND ESPCLY AFTER MIDNIGHT WHICH SHOULD ALLOW SOME CLEARING TO TAKE
PLACE. HOWEVER MODELS AGAIN SHOW A LOT OF RESIDUAL LOW LEVEL
MOISTURE LINGERING GIVEN WEAK NE FLOW OVERNIGHT SO LOW CONFIDENCE
IN WHETHER OR NOT WILL SEE MORE LOW CLOUDS OR FOG TO STRATU
SCENARIO MOST SPOTS OVERNIGHT. SINCE GUIDANCE HAS BEEN OVERDONE
WITH LOW CIGS OF LATE WILL GO WITH MORE DENSE FOG ESPCLY WHERE
RAIN HAS OCCURRED. THIS SUPPORTS LIFR/IFR AT KLWB/KBCB WITH
IFR/MVFR VSBYS AT KLYH IF CLOUDS DONT REDEVELOP. MAYBE SOME LOWER
MVFR CIGS AT ROA/DAN AND IFR AT BLF WHERE FOG SHOULD BE MORE
PATCHY MVFR NATURE AT THIS POINT.
FOG/LOW CLOUDS ERODE FRIDAY MORNING...WITH A RETURN TO OVERALL
VFR CONDITIONS UNDER HIGH PRESSURE...WITH ONLY ISOLATED SHOWERS
FRIDAY AFTERNOON...AND THEN MORE SCATTERED SHRA/TSRA COVERAGE
ESPCLY MOUNTAINS ON SATURDAY. DEEPER MOISTURE WILL MAKE A RETURN
LATER IN THE WEEKEND WITH MORE IN THE WAY OF CONVECTIVE DRIVEN
SUB-VFR CONDITIONS POSSIBLE WITH A PASSING WARM FRONT SUNDAY...AND
ANOTHER COLD FRONT LATER MONDAY. DRIER AIR LOOKS TO PUNCH IN
BEHIND THE COLD FRONT ON TUESDAY WITH A RETURN TO VFR MOST SPOTS
EXCEPT KBLF/KLWB WHERE LINGERING MVFR CIGS POSSIBLE ESPCLY EARLY
TUESDAY. OTHERWISE SOME PATCHY FOG LIKELY DURING THE OVERNIGHTS
INTO SUNDAY...WITH LATE NIGHT/EARLY MORNING MVFR/IFR CONDITIONS
LIKELY ESPECIALLY AT THE VALLEY LOCATIONS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/KK/WP
NEAR TERM...JH/KK
SHORT TERM...RCS
LONG TERM...RCS
AVIATION...JH/KK/WP
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
145 PM EDT WED AUG 28 2013
.SYNOPSIS...
A COLD FRONT WILL SLIDE SOUTH TO THE NORTH CAROLINA/VIRGINIA
BORDER BY THURSDAY MORNING. WEAK HIGH PRESSURE ARRIVES AFTER
THURSDAY. WARM FRONT HEADS NORTH ACROSS OUR AREA BY SUNDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 130 PM EDT WEDNESDAY...
ADJUSTED POPS AND TEMPERATURES WITH LAST RADAR AND OBS TRENDS.
TRIMMED POPS IN THE WEST AND INCREASED IN THE EAST. WITH HEALTHY
CLOUD COVER LOWERED HIGH TEMPERATURES FOR THIS AFTERNOON IN
SEVERAL LOCATIONS.
AS OF 935 AM EDT WEDNESDAY...
A SHORT-WAVE TROUGH OVER THE GREAT LAKES WILL TRAVEL SOUTHEAST TO
OFF THE MID ATLANTIC COAST BY TONIGHT. THIS MORNING 8AM/12Z RNK
SOUNDING DISPLAYED THE JUICY AIRMASS WITH PWATS AROUND 1.5 INCHES
WITH A WEST TO NORTHWEST FLOW. MODIFIED POPS FOR THE NEXT COUPLE
COUPLE OF HOURS TOWARDS THE HRRR WHICH LINED UP FAIRLY WELL WITH
WSR-88D TRENDS. CONTINUED THE HIGHER POPS FOR THIS AFTERNOON IN
THE NORTH AND EAST AS SUPPORT BY ECMWF...GFS AND NAM. SPC HAS
REMOVE THE SEE TEXT OF SEVERE WEATHER FROM OUR AREA WITH THE
EXPECTATION THAT WIDESPREAD CLOUDS WOULD INHIBIT AIRMASS
DESTABILIZATION. QUESTION OF HOW MUCH SUNSHINE WILL DETERMINE IF
WE HAVE ISOLATED SEVERE STORMS THIS AFTERNOON WITH THE THREAT FOR
GUSTY WINDS AND HEAVY RAINS. MORE LATER THIS AFTERNOON...
AS OF 730 AM EDT WEDNESDAY...
BUMPED UP POPS OVER THE NW CWA AS CONVECTION SLIDES SE INTO THE
SRN SHENANDOAH VALLEY. THIS WILL PROGRESS SE INTO THE PIEDMONT
THROUGH THE MORNING WITH EXPECTATIONS OF WEAKENING SOMEWHAT AS IT
CROSSES THE BLUE RIDGE. GIVEN EXTENT OF CLOUD COVER AND SHOWERS
THINKING IS THAT HIGHS TODAY WILL BE A COUPLE MORE DEGREES COOLER
AND LOWER THEM ESPECIALLY FROM THE BLUE RIDGE EAST. THIS MORNINGS
CONVECTION WILL LEAVE BEHIND SOME BOUNDARIES AND NEXT UPSTREAM
WAVE WILL INTERACT WITH THIS TO GENERATE MORE SHOWERS AND STORMS
THIS AFTERNOON. QUESTION REMAINS ON HOW MUCH SUN MAY PEAK
OUT...ESPECIALLY OUT EAST WHERE CLOUDS LOOK TO HANG LONGER. SVR
THREAT STILL APPEARS ISOLATED AND MAY BE MORE OVER THE SOUTHWEST
WHERE BETTER CHANCE OF SEEING SUN OCCURS...ALTHOUGH WILL BE
FURTHER AWAY FROM UPPER FORCING.
PREVIOUS DISCUSSION AT 330 AM...
JUICY AIRMASS WILL BE IN PLACE TODAY AS THETA-E RIDGE AND SFC FRONT
NORTH OF US SHIFTS ESE LATE TONIGHT. MODELS ARE TRACKING A PIECE OF
ENERGY ASSOCIATED WITH CONVECTION OVER THE EASTERN GREAT LAKES/WRN
PA THIS MORNING AND TAKING IT SOUTHEAST ACROSS EASTERN WV/VA INTO NE
NC LATER THIS MORNING INTO THIS EVENING. AT THIS TIME...THE 12Z
ECMWF AS WELL AS THE 00Z LOCAL WRF WERE HANDLING THE LOCATIONS OF
CONVECTION EARLY THOUGH THE ECMWF SEEMS OVERDONE. SEEING THE LATEST
00Z ECMWF THAT JUST ARRIVED KEEPS IT SIMILAR TO THE 12Z BUT A LITTLE
SLOWER IN TIMING. GIVEN WHERE THE THETA-E RIDGE LINES UP AND
MOVEMENT OF THE UPPER WAVE...THINK OUR NRN AND ERN CWA APPEARS TO BE
MORE IN LINE OVERALL TO RECEIVE MORE QPF....THEREFORE HIGHER POPS BY
THIS AFTERNOON. ROUGHLY EAST/NORTHEAST OF A LINE FROM LWB-ROA-DAN.
THE STORM PREDICTION CENTER HIGHLIGHTS US IN A SEE TEXT WITH 5
PERCENT THREAT OF SVR WINDS. MODEST WIND FIELDS AND HIGHER PWATS
FAVOR STRONG WIND GUSTS AND KEPT THE WORDING OF GUSTY WINDS FROM
PREVIOUS FORECAST FOR THE AFTERNOON PERIOD CWA WIDE. LIMITING FACTOR
EXPECTED TO BE CLOUD COVER. THE 00Z CMC/NAM SHOWING THE SOUTHWEST
FROM BLACKSBURG TO MARION SOUTH TO BOONE/WILKESBORO SEEING MORE SUN.
THIS MAY BE THE AREA TO WATCH FOR ISOLATED SVR...WHILE CLUSTER OF
STORMS WITH SHORTWAVE/MCS WILL IMPACT THE NORTHEAST CWA WITH HEAVIER
RAINS...AND LOCALLY SVR WINDS. WILL HIGHLIGHT THREAT OF HEAVY RAIN
AND ISOLATED SVR IN THE HWO.
DURING THE EVENING THE FOCUS SHIFTS MORE OVER THE PIEDMONT AND
COASTAL AREAS OF VA/NC AND WITH FRONT ENTERING THE CWA...MODELS KEEP
THE CONVERGENCE AND SHOWERS LINED UP ACROSS THE EAST/SOUTH EARLY
WITH LESS CHANCE IN THE NORTH AND SOUTHWEST...WITH SOME UPSLOPE
ENHANCEMENT IN SE WV. WITH THE NEW ECMWF SLOWING THINGS DOWN SOME
KEPT HIGHER POPS IN THE EVENING THEN START TO LOWER TO SLIGHT
CHANCE/LOW CHANCE OVERNIGHT.
FOR HIGHS TODAY...THREAT OF MORE CLOUDS AND CONVECTION IN THE
NORTHERN CWA SWAYS ME TO GO A COUPLE/3 DEGREES COOLER THAN MOS WITH
UPPER 70S HSP/LWB TO MID 80S LYH/FVX. OF COURSE IF ANY SUN WERE TO
STAY OUT FOR AN HOUR AND GIVEN DOWNSLOPE AHEAD OF FRONT...90 COULD
BE POSSIBLE AT LYH/FVX...BUT MODEL CLOUD FIELDS LEAD ME TO BELIEVE
COOLER IS MORE LIKELY. NOW THE FURTHER SOUTHWEST WE GO THE WARMER IT
WILL BE AS SUN WILL BE MIXED IN AT TIMES. STILL BEING THE POTENTIAL
FOR SOME CLOUDS FROM UPSTREAM CONVECTION SETTLED CLOSE TO MOS
GUIDANCE WITH LOWER TO MID 80S SOUTHWEST VA MOUNTAINS/VALLEYS TO MID
TO NEAR 90 ROANOKE/DANVILLE/NW NC PIEDMONT/FOOTHILLS.
LITTLE CHANGE IN AIRMASS TONIGHT SO LOWS WILL STAY WARM FROM THE MID
60S ACROSS THE ALLEGHANY HIGHLANDS/GREENBRIER VALLEY TO UPPER 60S TO
LOWER 70S ELSEWHERE.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
AS OF 345 AM EDT WEDNESDAY...
ALTHOUGH WEAK BOUNDARY WILL BE JUST TO OUR SOUTH THURSDAY...GOOD
SURFACE WIND CONVERGENCE ALONG THE SOUTHERN BLUE RIDGE SHOULD FORCE
SHOWERS AND THUNDERSTORMS FOR THE AFTERNOON. HOWEVER...MOISTURE
LOOKS RATHER SCANT IN THE MID LEVELS...SO THIS MAY BE A LIMITING
FACTOR. H85 TEMPS WILL ONLY BE A FEW DEGREES COOLER BEHIND THIS SO
CALLED FRONT WITH SURFACE DEWPOINTS STAYING IN THE SOUPY MID 60S.
LESS MOISTURE ALOFT IS WHAT REALLY KNOCKS DOWN THE PWATS IN
COMPARISON TO WEDNESDAY. WEAK HIGH PRESSURE WILL STRETCH FROM THE
MID ATLANTIC AND OFF THE COAST ON FRIDAY. WITH MORE OF AN EASTERLY
COMPONENT...INSTABILITY IS REDUCED...TEMPS ARE COOLER...WITH THIS
BEING THE DRIEST DAY OF THE SHORT TERM. HIGHEST POPS WILL BE PLACED
OVER NW NC. AS THE SURFACE HIGH MOVES OF THE COAST SATURDAY...WINDS
VEER TO MORE OF A SOUTHERLY DIRECTION. THIS ALLOWS MORE MOISTURE TO
RETURN BACK NORTH AND COMBINE WITH A DEEPENING TROUGH ACROSS THE
GREAT LAKES AND OHIO VALLEY TO PRODUCE MORE WIDESPREAD STORMS THAN
FRIDAY...WITH THE MOST ALONG THE BLUE RIDGE. WITH PWATS ELEVATED
ONCE AGAIN AND WEAK FLOW...THERE MAY BE THE POTENTIAL FOR SOME
BACKBUILDING HEAVY RAINERS AND WATER PROBLEMS. BASED ON THE CLOUDS
AND POTENTIAL FOR STORMS...DID STAY BELOW GUIDANCE THURSDAY AND
SATURDAY FOR HIGHS.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 115 PM EDT TUESDAY...
DIFFERENT MODEL GUIDANCE DURING THIS PORTION OF THE FORECAST PACKAGE
VARIES OF THE SPECIFICS...BUT IS FAIRLY CONSISTENT ON THE
GENERALITIES. GENERALLY SPEAKING...THE NORTHEAST U.S. IS EXPECTED TO
HAVE SOME DEGREE OF TROUGHINESS OVER IT DURING THIS PORTION OF THE
FORECAST...WITH NORTHWEST FLOW ALOFT OVER OUR REGION. CLOSER TO THE
SURFACE...HIGH PRESSURE WILL TAKE UP RESIDENCE ALONG THE EAST
COAST...AND PREVAILING FLOW AROUND IT WILL HELP DEVELOP FLOW FROM
THE SOUTH THAT WILL DIRECT MOISTURE INTO OUR REGION. DURING THE
MONDAY INTO TUESDAY TIME FRAME...A NORTHERN STREAM TROUGH WILL HELP
DEEPEN...AND THEN GRADUALLY EJECT THE EAST COAST TROUGH INTO THE
WESTERN ATLANTIC...AND UPPER LEVEL RIDGING WILL START NOSING INTO
THE AREA FROM THE MID-WEST.
THE ABOVE POINTS TOWARD THE FOLLOWING SCENARIO. MAINLY AFTERNOON AND
EARLY EVENING SCATTERED SHOWERS AND STORMS ARE EXPECTED SUNDAY
TRIGGERED PRIMARILY BE DAYTIME HEATING. HOWEVER...AND THIS IS
WHERE THE SPECIFICS GET TRICKY...UPSTREAM SHORTWAVE TROUGHS MAY
RIDE SOUTHEAST WITHIN THE NORTHWEST FLOW ALOFT AND ADD AN
INCREASED ELEMENT OF UPPER LEVEL DYNAMICS TO THE FORECAST PICTURE
AND THUS BETTER COVERAGE. SIMILARITY...THIS SAME FLOW MAY HELP
ADVECT AN UPSTREAM THUNDERSTORM COMPLEX INTO THE REGION...AND THIS
TOO WOULD ALLOW FOR BETTER COVERAGE OF SHOWERS AND
STORMS...ESPECIALLY ACROSS THE WESTERN PORTION OF THE AREA.
PINPOINTING THESE FEATURES IS WHERE MODEL GUIDANCE VARIES TOO
GREATLY TO TRY TO INCORPORATE EITHER OF THESE SCENARIOS INTO THE
FORECAST AT THIS TIME.
MONDAY INTO TUESDAY...GUIDANCE ALSO VARIES AS TO THE TIMING AND
TRACK OF THE NORTHERN STREAM SYSTEM AND THUS THE IMPACT AND TIMING
OF ITS ASSOCIATED SURFACE COLD FRONT. WE WILL OFFER A SOLUTION
COMPARABLE TO WHAT IS PUT FORTH BY WPC WITH MONDAY AFTERNOON AND
EVENING LOOKING THE MOST PROMISING CURRENTLY. WOULD NOT BE SURPRISED
AS WE DRAW NEARER TO THIS TIME FRAME THAT THE FRONT ENDS UP ARRIVING
MONDAY NIGHT INTO TUESDAY MORNING...OR LATER.
TEMPERATURES THROUGH THIS TIME FRAME SHOULD SLOWLY INCREASE THROUGH
MONDAY AHEAD OF THE COLD FRONT...AND THEN BE COOLER AND LESS HUMID
ON TUESDAY WITH OUR CURRENT FORECAST TIMING OF THE COLD FRONT.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 130 PM EDT WEDNESDAY...
AREAS OF MVFR LOW CLOUDS...FOG AND HAZE PRESIST THIS AFTERNOON
INTO THIS EVENING AS AN AREA OF SHOWERS MOVES SOUTHEAST OUT OF
CWA THIS AFTERNOON.
ANOTHER SHORTWAVE WILL DROP SOUTH ACROSS THE REGION INTO TONIGHT.
THIS SHOULD RESULT IN ADDITIONAL SHOWERS AND THUNDERSTORMS
DEVELOPING AND TRAVELING SOUTHEAST ACROSS THE REGION INTO THE
EVENING HOURS.
BY TONIGHT...THE MODELS TRACK THE PRECIPITATION EAST AND OFFSHORE
OVERNIGHT. CLOUDS MAY LINGER OVERNIGHT IN THE EAST BUT ENOUGH
CLEARING IN THE WEST COULD LEAD TO AREAS OF FOG ESPECAILLY AT
LWB/BLF AND BCB.
SPOTTY SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE FORECAST FOR
THURSDAY AS WEAK DISTURBANCES RIDE ACROSS THE AREA FROM THE GREAT
LAKES OVERTOP NORTHEASTERLY FLOW NEAR THE SURFACE AS HIGH
PRESSURE BUILDS IN. EXPECT A RETURN TO OVERALL VFR CONDITIONS UNDER
HIGH PRESSURE...WITH ONLY ISOLATED SHOWERS AT BEST FRIDAY AND
SATURDAY. OTHERWISE SOME PATCHY FOG LIKELY DURING THE OVERNIGHTS
INTO SATURDAY...WITH LATE NIGHT/EARLY MORNING MVFR/IFR CONDITIONS
POSSIBLE ESPECAILLY AT THE VALLEY LOCATIONS.
&&
.EQUIPMENT...
AS OF 100 PM EDT WEDNESDAY...
THE TEMPERATURE/DEWPOINT AT THE ROANOKE ASOS (ROA) WILL BE
AUGMENTED BY OBSERVERS FROM AN AUXILIARY UNIT UNTIL FURTHER
NOTICE. EL TECH WORKING ON REPAIRS AT THE ROANOKE AIRPORT THIS
AFTERNOON...TIME OF RESTORATION OF THE PRIMARY EQUIPMENT MAY BE
LATER THIS AFTERNOON.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WP/KK
NEAR TERM...KK/WP
SHORT TERM...KM
LONG TERM...DS
AVIATION...KK/WP
EQUIPMENT...AMS/KK
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
940 AM EDT WED AUG 28 2013
.SYNOPSIS...
A COLD FRONT WILL SLIDE FROM THE SOUTHERN GREAT LAKES THIS MORNING
SOUTH TO THE NORTH CAROLINA/VIRGINIA BORDER BY THURSDAY MORNING. WEAK
HIGH PRESSURE ARRIVES AFTER THURSDAY. WARM FRONT HEADS NORTH
ACROSS OUR AREA BY SUNDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 935 AM EDT WEDNESDAY...
A SHORT-WAVE TROUGH OVER THE GREAT LAKES WILL TRAVEL SOUTHEAST TO
OFF THE MID ATLANTIC COAST BY TONIGHT. THIS MORNING 8AM/12Z RNK
SOUNDING DISPLAYED THE JUICY AIRMASS WITH PWATS AROUND 1.5 INCHES
WITH A WEST TO NORTHWEST FLOW. MODIFIED POPS FOR THE NEXT COUPLE
COUPLE OF HOURS TOWARDS THE HRRR WHICH LINED UP FAIRLY WELL WITH
WSR-88D TRENDS. CONTINUED THE HIGHER POPS FOR THIS AFTERNOON IN
THE NORTH AND EAST AS SUPPORT BY ECMWF...GFS AND NAM. SPC HAS
REMOVE THE SEE TEXT OF SEVERE WEATHER FROM OUR AREA WITH THE
EXPECTATION THAT WIDESPREAD CLOUDS WOULD INHIBIT AIRMASS
DESTABILIZATION. QUESTION OF HOW MUCH SUNSHINE WILL DETERMINE IF
WE HAVE ISOLATED SEVERE STORMS THIS AFTERNOON WITH THE THREAT FOR
GUSTY WINDS AND HEAVY RAINS. MORE LATER THIS AFTERNOON...
AS OF 730 AM EDT WEDNESDAY...
BUMPED UP POPS OVER THE NW CWA AS CONVECTION SLIDES SE INTO THE
SRN SHENANDOAH VALLEY. THIS WILL PROGRESS SE INTO THE PIEDMONT
THROUGH THE MORNING WITH EXPECTATIONS OF WEAKENING SOMEWHAT AS IT
CROSSES THE BLUE RIDGE. GIVEN EXTENT OF CLOUD COVER AND SHOWERS
THINKING IS THAT HIGHS TODAY WILL BE A COUPLE MORE DEGREES COOLER
AND LOWER THEM ESPECIALLY FROM THE BLUE RIDGE EAST. THIS MORNINGS
CONVECTION WILL LEAVE BEHIND SOME BOUNDARIES AND NEXT UPSTREAM
WAVE WILL INTERACT WITH THIS TO GENERATE MORE SHOWERS AND STORMS
THIS AFTERNOON. QUESTION REMAINS ON HOW MUCH SUN MAY PEAK
OUT...ESPECIALLY OUT EAST WHERE CLOUDS LOOK TO HANG LONGER. SVR
THREAT STILL APPEARS ISOLATED AND MAY BE MORE OVER THE SOUTHWEST
WHERE BETTER CHANCE OF SEEING SUN OCCURS...ALTHOUGH WILL BE
FURTHER AWAY FROM UPPER FORCING.
PREVIOUS DISCUSSION AT 330 AM...
JUICY AIRMASS WILL BE IN PLACE TODAY AS THETA-E RIDGE AND SFC FRONT
NORTH OF US SHIFTS ESE LATE TONIGHT. MODELS ARE TRACKING A PIECE OF
ENERGY ASSOCIATED WITH CONVECTION OVER THE EASTERN GREAT LAKES/WRN
PA THIS MORNING AND TAKING IT SOUTHEAST ACROSS EASTERN WV/VA INTO NE
NC LATER THIS MORNING INTO THIS EVENING. AT THIS TIME...THE 12Z
ECMWF AS WELL AS THE 00Z LOCAL WRF WERE HANDLING THE LOCATIONS OF
CONVECTION EARLY THOUGH THE ECMWF SEEMS OVERDONE. SEEING THE LATEST
00Z ECMWF THAT JUST ARRIVED KEEPS IT SIMILAR TO THE 12Z BUT A LITTLE
SLOWER IN TIMING. GIVEN WHERE THE THETA-E RIDGE LINES UP AND
MOVEMENT OF THE UPPER WAVE...THINK OUR NRN AND ERN CWA APPEARS TO BE
MORE IN LINE OVERALL TO RECEIVE MORE QPF....THEREFORE HIGHER POPS BY
THIS AFTERNOON. ROUGHLY EAST/NORTHEAST OF A LINE FROM LWB-ROA-DAN.
THE STORM PREDICTION CENTER HIGHLIGHTS US IN A SEE TEXT WITH 5
PERCENT THREAT OF SVR WINDS. MODEST WIND FIELDS AND HIGHER PWATS
FAVOR STRONG WIND GUSTS AND KEPT THE WORDING OF GUSTY WINDS FROM
PREVIOUS FORECAST FOR THE AFTERNOON PERIOD CWA WIDE. LIMITING FACTOR
EXPECTED TO BE CLOUD COVER. THE 00Z CMC/NAM SHOWING THE SOUTHWEST
FROM BLACKSBURG TO MARION SOUTH TO BOONE/WILKESBORO SEEING MORE SUN.
THIS MAY BE THE AREA TO WATCH FOR ISOLATED SVR...WHILE CLUSTER OF
STORMS WITH SHORTWAVE/MCS WILL IMPACT THE NORTHEAST CWA WITH HEAVIER
RAINS...AND LOCALLY SVR WINDS. WILL HIGHLIGHT THREAT OF HEAVY RAIN
AND ISOLATED SVR IN THE HWO.
DURING THE EVENING THE FOCUS SHIFTS MORE OVER THE PIEDMONT AND
COASTAL AREAS OF VA/NC AND WITH FRONT ENTERING THE CWA...MODELS KEEP
THE CONVERGENCE AND SHOWERS LINED UP ACROSS THE EAST/SOUTH EARLY
WITH LESS CHANCE IN THE NORTH AND SOUTHWEST...WITH SOME UPSLOPE
ENHANCEMENT IN SE WV. WITH THE NEW ECMWF SLOWING THINGS DOWN SOME
KEPT HIGHER POPS IN THE EVENING THEN START TO LOWER TO SLIGHT
CHANCE/LOW CHANCE OVERNIGHT.
FOR HIGHS TODAY...THREAT OF MORE CLOUDS AND CONVECTION IN THE
NORTHERN CWA SWAYS ME TO GO A COUPLE/3 DEGREES COOLER THAN MOS WITH
UPPER 70S HSP/LWB TO MID 80S LYH/FVX. OF COURSE IF ANY SUN WERE TO
STAY OUT FOR AN HOUR AND GIVEN DOWNSLOPE AHEAD OF FRONT...90 COULD
BE POSSIBLE AT LYH/FVX...BUT MODEL CLOUD FIELDS LEAD ME TO BELIEVE
COOLER IS MORE LIKELY. NOW THE FURTHER SOUTHWEST WE GO THE WARMER IT
WILL BE AS SUN WILL BE MIXED IN AT TIMES. STILL BEING THE POTENTIAL
FOR SOME CLOUDS FROM UPSTREAM CONVECTION SETTLED CLOSE TO MOS
GUIDANCE WITH LOWER TO MID 80S SOUTHWEST VA MOUNTAINS/VALLEYS TO MID
TO NEAR 90 ROANOKE/DANVILLE/NW NC PIEDMONT/FOOTHILLS.
LITTLE CHANGE IN AIRMASS TONIGHT SO LOWS WILL STAY WARM FROM THE MID
60S ACROSS THE ALLEGHANY HIGHLANDS/GREENBRIER VALLEY TO UPPER 60S TO
LOWER 70S ELSEWHERE.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
AS OF 345 AM EDT WEDNESDAY...
ALTHOUGH WEAK BOUNDARY WILL BE JUST TO OUR SOUTH THURSDAY...GOOD
SURFACE WIND CONVERGENCE ALONG THE SOUTHERN BLUE RIDGE SHOULD FORCE
SHOWERS AND THUNDERSTORMS FOR THE AFTERNOON. HOWEVER...MOISTURE
LOOKS RATHER SCANT IN THE MID LEVELS...SO THIS MAY BE A LIMITING
FACTOR. H85 TEMPS WILL ONLY BE A FEW DEGREES COOLER BEHIND THIS SO
CALLED FRONT WITH SURFACE DEWPOINTS STAYING IN THE SOUPY MID 60S.
LESS MOISTURE ALOFT IS WHAT REALLY KNOCKS DOWN THE PWATS IN
COMPARISON TO WEDNESDAY. WEAK HIGH PRESSURE WILL STRETCH FROM THE
MID ATLANTIC AND OFF THE COAST ON FRIDAY. WITH MORE OF AN EASTERLY
COMPONENT...INSTABILITY IS REDUCED...TEMPS ARE COOLER...WITH THIS
BEING THE DRIEST DAY OF THE SHORT TERM. HIGHEST POPS WILL BE PLACED
OVER NW NC. AS THE SURFACE HIGH MOVES OF THE COAST SATURDAY...WINDS
VEER TO MORE OF A SOUTHERLY DIRECTION. THIS ALLOWS MORE MOISTURE TO
RETURN BACK NORTH AND COMBINE WITH A DEEPENING TROUGH ACROSS THE
GREAT LAKES AND OHIO VALLEY TO PRODUCE MORE WIDESPREAD STORMS THAN
FRIDAY...WITH THE MOST ALONG THE BLUE RIDGE. WITH PWATS ELEVATED
ONCE AGAIN AND WEAK FLOW...THERE MAY BE THE POTENTIAL FOR SOME
BACKBUILDING HEAVY RAINERS AND WATER PROBLEMS. BASED ON THE CLOUDS
AND POTENTIAL FOR STORMS...DID STAY BELOW GUIDANCE THURSDAY AND
SATURDAY FOR HIGHS.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 115 PM EDT TUESDAY...
DIFFERENT MODEL GUIDANCE DURING THIS PORTION OF THE FORECAST PACKAGE
VARIES OF THE SPECIFICS...BUT IS FAIRLY CONSISTENT ON THE
GENERALITIES. GENERALLY SPEAKING...THE NORTHEAST U.S. IS EXPECTED TO
HAVE SOME DEGREE OF TROUGHINESS OVER IT DURING THIS PORTION OF THE
FORECAST...WITH NORTHWEST FLOW ALOFT OVER OUR REGION. CLOSER TO THE
SURFACE...HIGH PRESSURE WILL TAKE UP RESIDENCE ALONG THE EAST
COAST...AND PREVAILING FLOW AROUND IT WILL HELP DEVELOP FLOW FROM
THE SOUTH THAT WILL DIRECT MOISTURE INTO OUR REGION. DURING THE
MONDAY INTO TUESDAY TIME FRAME...A NORTHERN STREAM TROUGH WILL HELP
DEEPEN...AND THEN GRADUALLY EJECT THE EAST COAST TROUGH INTO THE
WESTERN ATLANTIC...AND UPPER LEVEL RIDGING WILL START NOSING INTO
THE AREA FROM THE MID-WEST.
THE ABOVE POINTS TOWARD THE FOLLOWING SCENARIO. MAINLY AFTERNOON AND
EARLY EVENING SCATTERED SHOWERS AND STORMS ARE EXPECTED SUNDAY
TRIGGERED PRIMARILY BE DAYTIME HEATING. HOWEVER...AND THIS IS
WHERE THE SPECIFICS GET TRICKY...UPSTREAM SHORTWAVE TROUGHS MAY
RIDE SOUTHEAST WITHIN THE NORTHWEST FLOW ALOFT AND ADD AN
INCREASED ELEMENT OF UPPER LEVEL DYNAMICS TO THE FORECAST PICTURE
AND THUS BETTER COVERAGE. SIMILARITY...THIS SAME FLOW MAY HELP
ADVECT AN UPSTREAM THUNDERSTORM COMPLEX INTO THE REGION...AND THIS
TOO WOULD ALLOW FOR BETTER COVERAGE OF SHOWERS AND
STORMS...ESPECIALLY ACROSS THE WESTERN PORTION OF THE AREA.
PINPOINTING THESE FEATURES IS WHERE MODEL GUIDANCE VARIES TOO
GREATLY TO TRY TO INCORPORATE EITHER OF THESE SCENARIOS INTO THE
FORECAST AT THIS TIME.
MONDAY INTO TUESDAY...GUIDANCE ALSO VARIES AS TO THE TIMING AND
TRACK OF THE NORTHERN STREAM SYSTEM AND THUS THE IMPACT AND TIMING
OF ITS ASSOCIATED SURFACE COLD FRONT. WE WILL OFFER A SOLUTION
COMPARABLE TO WHAT IS PUT FORTH BY WPC WITH MONDAY AFTERNOON AND
EVENING LOOKING THE MOST PROMISING CURRENTLY. WOULD NOT BE SURPRISED
AS WE DRAW NEARER TO THIS TIME FRAME THAT THE FRONT ENDS UP ARRIVING
MONDAY NIGHT INTO TUESDAY MORNING...OR LATER.
TEMPERATURES THROUGH THIS TIME FRAME SHOULD SLOWLY INCREASE THROUGH
MONDAY AHEAD OF THE COLD FRONT...AND THEN BE COOLER AND LESS HUMID
ON TUESDAY WITH OUR CURRENT FORECAST TIMING OF THE COLD FRONT.
&&
.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
AS OF 740 AM EDT WEDNESDAY...
SHOWERS/SOME THUNDER EXITING THE LWB AREA AND MAY SEE SHOWERS
AFFECT ROA/LYH THIS MORNING BUT TREND IS FOR WEAKENING. STILL
LOOKS LIKE ANY LOWER CLOUDS/RESIDUAL FOG THIS MORNING WILL MIXT
OUT TO VFR BY 15Z WITH SOME HAZE LINGERING.
NEXT UPSTREAM WAVE WILL BE EXPECTED TO ARRIVE THIS AFTERNOON AND
SHOULD GENERATE A GOOD COVERAGE OF SHOWERS AND SOME TSRA EAST OF
THE LWB/ROA/DAN LINE. HERE HAVE STILL KEPT IT VCTS WITH
PREDOMINANT SHRA. BEST CHANCE FOR THUNDER HITTING A TERMINAL
APPEARS TO BE LYH...BUT CLOUD COVER MAY LIMIT CONVECTION SOME.
FURTHER WEST...THERE WILL REMAIN SOME CHANCE OF SHOWERS/STORMS
BUT LOOKS LIKE BLF WILL BE ON THE EDGE. BY THIS EVENING THE MODELS
TRACK THE PRECIP EAST AND OFFSHORE OVERNIGHT. CLOUDS MAY LINGER
OVERNIGHT IN THE EAST BUT ENOUGH CLEARING IN THE WEST COULD LEAD
TO SOME FOG ISSUES AT LWB/BLF AND BCB...MEANING IFR OR WORSE.
SPOTTY SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE FORECAST FOR
THURSDAY AS WEAK DISTURBANCES RIDE ACROSS THE AREA FROM THE GREAT
LAKES OVERTOP NORTHEASTERLY FLOW NEAR THE SURFACE AS HIGH
PRESSURE BUILDS IN. EXPECT A RETURN TO OVERALL VFR CONDITIONS UNDER
HIGH PRESSURE...WITH ONLY ISOLATED SHOWERS AT BEST FRIDAY AND
SATURDAY. OTHERWISE SOME PATCHY FOG LIKELY DURING THE OVERNIGHTS
INTO SATURDAY...WITH LATE NIGHT/EARLY MORNING MVFR/IFR CONDITIONS
POSSIBLE ESPECIALLY AT THE VALLEY LOCATIONS.
&&
.EQUIPMENT...
AS OF 400 AM EDT WEDNESDAY...
THE TEMPERATURE/DEWPOINT AT THE ROANOKE ASOS (ROA) WILL BE
AUGMENTED BY OBSERVERS FROM AN AUXILIARY UNIT UNTIL FURTHER
NOTICE. TIME OF RESTORATION OF THE PRIMARY EQUIPMENT WILL BE
LATER TODAY AT THE EARLIEST.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WP
NEAR TERM...KK/WP
SHORT TERM...KM
LONG TERM...DS
AVIATION...NF/WP
EQUIPMENT...AMS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
158 AM EDT WED AUG 28 2013
.SYNOPSIS...
A COLD FRONT WILL SLIDE FROM THE SOUTHERN GREAT LAKES THIS MORNING
SOUTH TO THE NORTH CAROLINA/VIRGINIA BORDER BY THURSDAY MORNING. WEAK
HIGH PRESSURE WILL ARRIVE BEHIND THIS COLD FRONT FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 115 AM EDT WEDNESDAY...
UPDATED FORECAST TO SLOW DOWN ONSET OF SHOWERS FROM UPSTREAM
SHOWERS OVER OHIO/WRN PA INTO THE GREAT LAKES. MID/HIGH CLOUDS ARE
IN AND OUT OVER THE AREA LEADING TO FOG AT TIMES IN THE CLEAR
BREAKS. OVERALL THINK FOG WILL BE PATCHY AND POSSIBLY DENSE AT
TIMES AS SKIES SHOULD BE CLOUDING UP AGAIN BY DAWN AS THE UPSTREAM
ACTIVITY NEARS. THE 12Z ECMWF APPEARS TO BE HANDLING THIS THE BEST
ATTM...ALONG WITH THE 03Z HRRR AND 00Z RAP. STILL LOOKS LIKE MAIN
FOCUS OF SHOWERS/STORMS BY MID MORNING INTO THE AFTERNOON WILL BE
ALONG AND EAST OF A LWB-ROA-MTV LINE.
PREVIOUS VALID DISCUSSION...
CONFIDENT ENOUGH THAT THE NORTHERN PART OF THE FORECAST AREA WILL
SEE RAINFALL WEDNESDAY MORNING TO GO WITH LIKELY RAIN CHANCES IN
THE FORECAST.
TIMING OF THE ARRIVAL OF THESE SHOWERS AND THUNDERSTORMS IS JUST
AS CRITICAL AS THE TRACK THE STORMS TAKE...AS INCREASED CLOUD
COVER DURING THE MORNING WILL HAVE A LIMITING AFFECT ON HEATING
AND INSTABILITY AS WE HEAD INTO THE AFTERNOON. AS SUCH...WHILE
RAIN WILL BE SCATTERED ACROSS THE AREA...STRONG THUNDERSTORM
ACTIVITY MAY REMAIN MORE ISOLATED. WILL KEEP AN EYE ON THIS
APPROACHING DISTURBANCE THROUGH THE NIGHT...AND ADJUST THE
FORECAST ACCORDINGLY.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY/...
AS OF 245 PM EDT TUESDAY...
WHAT PRECIPITATION WE HAVE AROUND WEDNESDAY EVENING WILL BE
DEPENDENT UPON HOW QUICKLY UPSTREAM CONVECTION TRAVERSES THE AREA
DURING THE DAY WEDNESDAY. OUR FORECAST WILL REFLECT ONE THAT HAS THE
WESTERN EXTENT OF ANY COMPLEX STILL ACROSS MAINLY THE NORTHERN AND
EASTERN PARTS OF THE AREA DURING THE EARLY EVENING. THE BULK OF THE
ACTIVITY WILL EXIT THE FORECAST AREA BY THE LATE EVENING. IN ITS
WAKE WILL BE LINGERING ISOLATED SHOWERS THROUGHOUT THE REMAINDER OF
THE NIGHT.
ON THURSDAY...WE WILL BE IN BETWEEN THE ROBUST NORTHWEST FLOW SYSTEM
AS OUR STEERING FLOW BECOMES MORE NORTHERLY TO NORTHEASTERLY. MODEL
GUIDANCE VARIES ON THE DEGREE OF COVERAGE OF SHOWERS AND
STORMS...BUT THE GENERAL TREND IS FOR A CONTINUATION OF ISOLATED TO
SCATTERED ACTIVITY AS COLD FRONT DRAWS CLOSER TO OUR NORTH.
ANY DAYTIME ACTIVITY SHOULD BEGIN TO WANE AROUND SUNSET WITH
ISOLATED SHOWERS POSSIBLE THROUGH ABOUT MIDNIGHT. THE CANADIAN AND
NAM SOLUTIONS ARE SUGGESTING LOW LEVEL FLOW BECOMES SOUTHEAST ACROSS
THE NORTHERN MOUNTAINS AND FOOTHILLS OF NORTH CAROLINA LATE THURSDAY
NIGHT. THIS WITH LINGERING MOISTURE IS ENOUGH TO ALLOW FOR SOME
ISOLATED SHOWERS IN THIS AREA BY DAYBREAK FRIDAY.
ON FRIDAY...LOW LEVEL FLOW BEGINS TO TREND MORE SOUTHERLY AS THE
SURFACE HIGH HEADS TOWARD THE EAST COAST. THIS HELPS BRING MOISTURE
BACK TO A GREATER EXTENT OF THE FORECAST AREA AND TOWARD THE FRONT
NORTH OF THE REGION. MODELS VARY ON THE LOCATION AND TIMING...BUT
THERE IS A HINT OF A WEAK SHORTWAVE TROUGH CROSSING THE AREA BY
FRIDAY AFTERNOON. THIS ALONG WITH DAYTIME HEATING WILL ALLOW FOR
ANOTHER DAY OF ISOLATED TO SCATTERED SHOWERS AND STORMS. AREAS ALONG
AND WEST OF THE CREST OF THE BLUE RIDGE WILL BE THE FOCUS FOR THE
BEST CONCENTRATION.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 115 PM EDT TUESDAY...
DIFFERENT MODEL GUIDANCE DURING THIS PORTION OF THE FORECAST PACKAGE
VARIES OF THE SPECIFICS...BUT IS FAIRLY CONSISTENT ON THE
GENERALITIES. GENERALLY SPEAKING...THE NORTHEAST U.S. IS EXPECTED TO
HAVE SOME DEGREE OF TROUGHINESS OVER IT DURING THIS PORTION OF THE
FORECAST...WITH NORTHWEST FLOW ALOFT OVER OUR REGION. CLOSER TO THE
SURFACE...HIGH PRESSURE WILL TAKE UP RESIDENCE ALONG THE EAST
COAST...AND PREVAILING FLOW AROUND IT WILL HELP DEVELOP FLOW FROM
THE SOUTH THAT WILL DIRECT MOISTURE INTO OUR REGION. DURING THE
MONDAY INTO TUESDAY TIME FRAME...A NORTHERN STREAM TROUGH WILL HELP
DEEPEN...AND THEN GRADUALLY EJECT THE EAST COAST TROUGH INTO THE
WESTERN ATLANTIC...AND UPPER LEVEL RIDGING WILL START NOSING INTO
THE AREA FROM THE MID-WEST.
THE ABOVE POINTS TOWARD THE FOLLOWING SCENARIO. MAINLY AFTERNOON AND
EARLY EVENING SCATTERED SHOWERS AND STORMS ARE EXPECTED SATURDAY AND
SUNDAY TRIGGERED PRIMARILY BE DAYTIME HEATING. HOWEVER...AND THIS IS
WHERE THE SPECIFICS GET TRICKY...UPSTREAM SHORTWAVE TROUGHS MAY RIDE
SOUTHEAST WITHIN THE NORTHWEST FLOW ALOFT AND ADD AN INCREASED
ELEMENT OF UPPER LEVEL DYNAMICS TO THE FORECAST PICTURE AND THUS
BETTER COVERAGE. SIMILARITY...THIS SAME FLOW MAY HELP ADVECT AN
UPSTREAM THUNDERSTORM COMPLEX INTO THE REGION...AND THIS TOO WOULD
ALLOW FOR BETTER COVERAGE OF SHOWERS AND STORMS...ESPECIALLY ACROSS
THE WESTERN PORTION OF THE AREA. PINPOINTING THESE FEATURES IS WHERE
MODEL GUIDANCE VARIES TOO GREATLY TO TRY TO INCORPORATE EITHER OF
THESE SCENARIOS INTO THE FORECAST AT THIS TIME.
MONDAY INTO TUESDAY...GUIDANCE ALSO VARIES AS TO THE TIMING AND
TRACK OF THE NORTHERN STREAM SYSTEM AND THUS THE IMPACT AND TIMING
OF ITS ASSOCIATED SURFACE COLD FRONT. WE WILL OFFER A SOLUTION
COMPARABLE TO WHAT IS PUT FORTH BY WPC WITH MONDAY AFTERNOON AND
EVENING LOOKING THE MOST PROMISING CURRENTLY. WOULD NOT BE SURPRISED
AS WE DRAW NEARER TO THIS TIME FRAME THAT THE FRONT ENDS UP ARRIVING
MONDAY NIGHT INTO TUESDAY MORNING...OR LATER.
TEMPERATURES THROUGH THIS TIME FRAME SHOULD SLOWLY INCREASE THROUGH
MONDAY AHEAD OF THE COLD FRONT...AND THEN BE COOLER AND LESS HUMID
ON TUESDAY WITH OUR CURRENT FORECAST TIMING OF THE COLD FRONT.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 145 AM EDT WEDNESDAY...
MID AND HIGH CLOUDS IN AND OUT OF TAF SITES WILL GIVE THE
VSBY FITS...AS SHOULD SEE SOME LOWERING VSBYS WITH ANY
CLEARING/THINNING OF HIGHER CLOUDS BUT SHOULD SEE OVERALL NO WORSE
THAN MVFR OVER MOST SITES DUE TO INCREASING HIGHER CLOUDS ARRIVING
BY 12Z FROM UPSTREAM CONVECTION. HOWEVER WILL THROW IN TEMPO
GROUPS ESPECIALLY DAN/BCB/BLF/LWB GIVEN THEY MAY HAVE LESS CLOUDS
OR ARE CLIMATOLOGICALLY FAVORED FOR LOWER VSBYS.
WILL SEE SHOWERS WORKING TOWARD LWB/ROA/LYH AROUND 12-15Z BUT
WEAKENING SOME. AS SHORTWAVE MOVES ACROSS NRN VA INTO THE
TIDEWATER THIS AFTERNOON WILL SEE INCREASING THREAT OF SHOWERS AND
SOME THUNDER ALTHOUGH INSTABILITY MAY BE ERASED SOME BY CLOUD
COVER...SO WILL TAKE TS OUT OF THE PREDOMINANT GROUP AND GO VCTS.
LOOKS LIKELY THAT ALONG AND EAST OF THE LWB-ROA-MTV LINE WILL SEE
BETTER THREAT OF SHOWERS. WILL KEEP TAFS VFR AFTER ANY FOG OR
LOWER CLOUDS MIX OUT BY MID MORNING...BUT DO NOT BE SURPRISED FOR
HEAVIER DOWNPOURS AROUND LYH THIS AFTERNOON TO NUDGE THEIR
VSBYS/CIGS TO UNDER VFR. A WEST TO NW WIND COMPONENT EXPECTED TO
BE PREVAILING AT 5-10 KNOTS AFTER 15Z THEN FALLING OFF AGAIN AFTER
00Z THU.
DURING THE EVENING THE SHOWERS/STORMS ARE EXPECTED TO TAKE A
DOWNWARD SHIFT WITH MODELS CONCENTRATING MORE ON A COMPLEX MOVING
FROM DCA-RIC-ORF. MAY SEE LINGERING SHOWERS IN LYH/DAN THOUGH.
SUBSIDENCE BEHIND THIS SYSTEM ALLOW SOME CLEARING TO START IN THE
WEST THIS EVENING THEN PERHAPS SPREAD EAST THU MORNING. THIS
COULD SET UP A SITUATION FOR DENSE FOG BUT LIMITING FACTOR MAY
STILL BE SOME DEBRIS CLOUDS AND SOME WIND.
SPOTTY SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE FORECAST FOR
THURSDAY AS WEAK DISTURBANCES RIDE ACROSS THE AREA FROM THE GREAT
LAKES OVERTOP NORTHEASTERLY FLOW NEAR THE SURFACE AS HIGH
PRESSURE BUILDS IN. EXPECT A RETURN TO OVERALL VFR CONDITIONS UNDER
HIGH PRESSURE...WITH ONLY ISOLATED SHOWERS AT BEST FRIDAY AND
SATURDAY. OTHERWISE SOME PATCHY FOG LIKELY DURING THE OVERNIGHTS
INTO SATURDAY...WITH LATE NIGHT/EARLY MORNING MVFR/IFR CONDITIONS
POSSIBLE ESPECIALLY AT THE VALLEY LOCATIONS.
&&
.EQUIPMENT...
AS OF 100 PM EDT TUESDAY...
THE TEMPERATURE/DEWPOINT AT THE ROANOKE ASOS (ROA) WILL BE
AUGMENTED BY OBSERVERS FROM AN AUXILIARY UNIT UNTIL FURTHER
NOTICE. TIME OF RESTORATION OF THE PRIMARY EQUIPMENT WILL BE
WEDNESDAY AT THE EARLIEST.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS/NF/WP
NEAR TERM...AMS/NF/WP
SHORT TERM...DS
LONG TERM...DS
AVIATION...NF/WP
EQUIPMENT...AMS
AREA FORECAST DISCUSSION...UPDATED
NWS SPOKANE WA
532 PM PDT Thu Aug 29 2013
.SYNOPSIS...
Warm late-summer weather is expected over the Inland Northwest
through the upcoming holiday weekend. The passage of a cold front
late tonight will deliver a few showers and thunderstorms with a
small chance returning on Friday to the for a small portion of
northeast Washington and the Idaho Panhandle. The Labor Day
weekend is looking warmer than average with an abundance of
sunshine. A transition to a showery weather pattern is expected to
begin either Monday and could persist through much of next week.
&&
.DISCUSSION...
Update this evening is to freshen the shower and thunderstorm
potential. The fast moving negatively tilted shortwave has quickly
moved out of the area and we are currently void of any showers and
thunderstorms in our area. There are some pretty decent showers
and thunderstorms developing across western WA and OR and may move
up the Cascades later this evening. So have taken out all evening
weather wording except for in the Cascades. Cold front passes
overnight. HRRR suggests a line of showers and possible
thunderstorms developing from eastern Columbia Basin after
midnight and moving into eastern WA and ID Panhandle overnight
into the early morning hours on Friday. /Nisbet
&&
.AVIATION...
00Z TAFS: Quiet wx anticipated for the next several hours.
Stronger storms on the west side of the state may cross into the
eastern Cascades later this evening. Nothing expected attm for the
KEAT terminal. Cold front passes overnight tonight with a line of
showers and thunderstorms developing and potentially impacting
KGEG...KSFF...KCOE and KPUW btwn 09-14z. Post frontal
southwesterly winds 10-15 mph with gusts up to 25 mph can be
expected Friday afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 59 78 56 82 57 91 / 20 10 0 0 0 0
Coeur d`Alene 57 78 54 81 53 90 / 20 20 0 0 0 0
Pullman 53 78 48 83 49 93 / 10 10 0 0 0 0
Lewiston 64 86 59 89 61 99 / 10 10 0 0 0 0
Colville 56 83 50 85 49 93 / 20 10 0 0 0 0
Sandpoint 54 77 47 79 45 86 / 20 20 0 0 0 0
Kellogg 56 75 53 80 53 88 / 10 20 0 0 0 0
Moses Lake 58 84 54 86 56 93 / 10 10 0 0 0 0
Wenatchee 62 82 59 84 61 89 / 10 0 0 0 0 0
Omak 58 82 55 85 55 91 / 10 10 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
935 PM MST THU AUG 29 2013
.UPDATE...UPDATED AVIATION DISCUSSION.
&&
.SYNOPSIS...
THE REST OF THIS WEEK WILL SEE INCREASED MONSOON ACTIVITY WITH THE
POTENTIAL FOR LOCALIZED HEAVY RAINFALL AS A WEATHER DISTURBANCE AND
A VERY MOIST AIRMASS AFFECT THE REGION. MUCH COOLER AND CLOUDY
CONDITIONS ARE EXPECTED FRIDAY WITH TEMPERATURES REMAINING
BELOW NORMAL THROUGH THE WEEKEND. A RETURN TO A MORE TYPICAL MONSOON
PERIOD WITH WARMER TEMPERATURES IS EXPECTED FROM SUNDAY INTO NEXT
WEEK.
&&
.DISCUSSION...
CONVECTION THIS AFTERNOON AND EVENING HAS GENERALLY BEEN SCATTERED
IN COVERAGE BUT PREVALENT ACROSS A LARGE AREA AS FAR WEST AS SE CA.
LATEST GPS-IPW IN TEMPE MEASURED MORE THAN 2 INCHES AND WITH THE
ANOMALOUSLY MOIST AIR MASS IN PLACE...MAIN CONCERN HAS BEEN
LOCALIZED HEAVY RAIN AND FLOODING. TEMPERATURES THIS EVENING HAVE
DROPPED INTO THE 80S ACROSS THE LOWER DESERTS WHICH HAS CUT DOWN ON
THE SURFACE-BASED INSTABILITY. ANOTHER FACTOR WHICH APPEARS TO HAVE
INHIBITED CONVECTION IS THE PRESENCE OF WEAK MID-LEVEL LAPSE RATES
ASSOCIATED WITH A WARM LAYER NEAR 450 MB EVIDENT ON THE 00Z PSR
SOUNDING. LATEST RADAR SHOWS LITTLE IN THE WAY OF SHOWER AND
THUNDERSTORM ACTIVITY...EXCEPT FOR SCATTERED CELLS ACROSS THE HIGHER
TERRAIN WELL EAST OF PHOENIX. FLOOD WATCH HAS BEEN CANCELLED FOR ALL
AREAS EXCEPT FOR AZZ024.
FOR THE REMAINDER OF TONIGHT...ISOLATED ACTIVITY FORCED BY A
WELL-DEFINED VORT MAX ACROSS EAST-CENTRAL AZ WILL PERSIST ACROSS
SOUTHERN GILA COUNTY. THIS WILL LIKELY TRIGGER ADDITIONAL CELLS
FURTHER WEST...PERHAPS INTO EASTERN MARICOPA AND PINAL
COUNTIES...THOUGH ALL HI-RES GUIDANCE INCLUDING THE HRRR INDICATES
THAT STORMS WILL BE ON A DOWNWARD TREND THROUGH MIDNIGHT. LATEST WV
IMAGERY ALSO SHOWS A WELL-FORMED MCS NEAR LAKE HAVASU WHICH SUGGESTS
THE POTENTIAL FOR GRAVITY WAVE PROPAGATION INTO EASTERN RIVERSIDE
COUNTY AND JTNP. DEWPOINTS AS HIGH AS THE UPPER 70S PERSIST ACROSS
SE CA AND ADDITIONAL CONVECTION CANNOT BE RULED OUT OVERNIGHT IN
THESE AREAS. POPS WERE LOWERED THROUGH MORNING BUT REMAIN
CONSIDERABLY ABOVE CLIMO.
&&
.PREVIOUS DISCUSSION...
FRIDAY SHOULD ALSO BE AN ACTIVE DAY WITH LITTLE TO NO CHANGE IN
AIRMASS CONDITIONS AND MODELS INDICATE THE SHORTWAVE NOW OVER NEW
MEXICO SLIDES WESTWARD INTO CENTRAL ARIZONA LATE TONIGHT INTO FRIDAY
MORNING. THE COVERAGE OF STORMS ON FRIDAY WILL LIKELY AGAIN DEPEND
ON THE AMOUNT OF INSOLATION...BUT AREAWIDE PWATS OF 1.75 TO 2 INCHES
SHOULD ALLOW FOR SOME LOCALIZED HEAVY RAINFALL AND FLOODING.
THE TROPICAL MOISTURE FEED WILL GRADUALLY SHIFT TO THE SOUTHWEST
THIS WEEKEND ALLOWING FOR A GRADUAL DECREASE IN MOISTURE ACROSS THE
DESERT SOUTHWEST. BOTH THE GFS AND EUROPEAN INDICATE SOME SORT OF
LINGERING INVERTED TROUGH ACROSS THE NORTHERN HALF OF
ARIZONA...ALLOWING FOR MUCH OF THE MONSOON ACTIVITY TO BE FOCUSED
ALONG THE MOGOLLON RIM AND HIGHER TERRAIN LOCATIONS OF EASTERN
ARIZONA. STILL EXPECTING MONSOON ACTIVITY ACROSS SOUTHERN ARIZONA TO
BE SOMEWHAT ACTIVE...BUT WILL MOSTLY BE RELIANT ON OUTFLOWS FOR
DEVELOPMENT ACROSS THE LOWER DESERTS. A GRADUAL DECREASE IN POPS IS
IN THE FORECAST FOR SATURDAY WITH SLIGHT CHANCE POPS FURTHER WEST
AND CHANCE POPS ACROSS MUCH OF SOUTH-CENTRAL ARIZONA. SUNDAY SHOULD
SEE EVEN LESS STORM CHANCES ACROSS SOUTHEAST CALIFORNIA AND
SOUTHWEST ARIZONA AS DRY AIR STARTS TO FILTER IN FROM THE WEST...BUT
CHANCE POPS IS AGAIN EXPECTED ACROSS SOUTH-CENTRAL ARIZONA.
TEMPERATURES WILL GRADUALLY WARM UP THIS WEEKEND WITH LOWER DESERT
HIGHS NEAR 100 BOTH DAYS.
NEXT WEEK IS SHAPING UP TO BE A TRANSITION FROM A SEMI-ACTIVE TO
NEAR NORMAL MONSOON PERIOD ON MONDAY AND TUESDAY TO DRIER AND WARMER
CONDITIONS FOR THE LATER PART OF NEXT WEEK. LONG RANGE MODELS SHOW
THE SUB-TROPICAL HIGH CENTERING ITSELF OVER COLORADO AND HEIGHTS
BUILDING ACROSS THE REGION. BY LATE NEXT WEEK...HIGH TEMPERATURES
COULD BE TOPPING OUT IN THE 105-108 RANGE ACROSS THE LOWER
DESERTS.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
ISOLATED THUNDERSTORMS REMAIN A THREAT OVERNIGHT...THOUGH CHANCES
ARE CONSIDERABLY HIGHER ACROSS THE HIGHER TERRAIN EAST OF PHOENIX.
OTHERWISE...MID CLOUDS WILL PERSIST INTO FRIDAY WITH CIGS AROUND
12-15K FT. CONVECTION IS EXPECTED TO REDEVELOP FRIDAY AFTERNOON ACROSS
SOUTH-CENTRAL AZ...THOUGH IT REMAINS HIGHLY UNCERTAIN AS TO EXACTLY
WHERE/WHEN THIS WILL OCCUR. CONDITIONS REMAIN EXCEPTIONALLY MOIST SO
IT IS MORE LIKELY THAT LIGHTNING AND WET RUNWAYS WILL BE MORE A
FACTOR THAN WIND/DUST IMPACTS.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
CONVECTION HAS ENDED ACROSS THE AREA...THOUGH THERE IS A SLIGHT
CHANCE THAT ADDITIONAL STORMS WILL AFFECT KBLH OVERNIGHT. FOR
FRIDAY...SHOWERS AND THUNDERSTORMS ARE GENERALLY EXPECTED TO REMAIN
WELL NORTH OF THE AREA AND ALONG THE PENINSULAR RANGES OF SOUTHERN
CA. TAF FORECAST IS CONSEQUENTLY WEIGHTED TOWARDS CLIMO.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
TROPICAL MOISTURE WILL GRADUALLY DIMINISH SATURDAY THROUGH THE
MIDDLE OF NEXT WEEK...AS MONSOON CONDITIONS RETURN TO CLIMATIC
NORMALS. BELOW SEASONAL NORMAL HIGH TEMPERATURES SATURDAY WILL
STEADILY CLIMB AND REACH TO NORMAL VALUES BY ABOUT TUESDAY...AND
ELEVATED HUMIDITIES SATURDAY WILL GRADUALLY LOWER DAY TO DAY...
FINALLY FALLING INTO THE TEENS BY NEXT WEDNESDAY. WINDS WILL
GENERALLY FOLLOW NORMAL DIURNAL TENDENCIES WITH TYPICAL AFTERNOON
AND EARLY EVENING GUSTINESS...ESPECIALLY OVER FAVORED HIGHER TERRAIN
LOCATIONS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...FLASH FLOOD WATCH UNTIL 11 PM MST THIS EVENING AZZ024.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...KUHLMAN
AVIATION...HIRSCH
FIRE WEATHER...CB
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
900 PM MST THU AUG 29 2013
.SYNOPSIS...
THE REST OF THIS WEEK WILL SEE INCREASED MONSOON ACTIVITY WITH THE
POTENTIAL FOR LOCALIZED HEAVY RAINFALL AS A WEATHER DISTURBANCE AND
A VERY MOIST AIRMASS AFFECT THE REGION. MUCH COOLER AND CLOUDY
CONDITIONS ARE EXPECTED FRIDAY WITH TEMPERATURES REMAINING
BELOW NORMAL THROUGH THE WEEKEND. A RETURN TO A MORE TYPICAL MONSOON
PERIOD WITH WARMER TEMPERATURES IS EXPECTED FROM SUNDAY INTO NEXT
WEEK.
&&
.DISCUSSION...
CONVECTION THIS AFTERNOON AND EVENING HAS GENERALLY BEEN SCATTERED
IN COVERAGE BUT PREVALENT ACROSS A LARGE AREA AS FAR WEST AS SE CA.
LATEST GPS-IPW IN TEMPE MEASURED MORE THAN 2 INCHES AND WITH THE
ANOMALOUSLY MOIST AIR MASS IN PLACE...MAIN CONCERN HAS BEEN
LOCALIZED HEAVY RAIN AND FLOODING. TEMPERATURES THIS EVENING HAVE
DROPPED INTO THE 80S ACROSS THE LOWER DESERTS WHICH HAS CUT DOWN ON
THE SURFACE-BASED INSTABILITY. ANOTHER FACTOR WHICH APPEARS TO HAVE
INHIBITED CONVECTION IS THE PRESENCE OF WEAK MID-LEVEL LAPSE RATES
ASSOCIATED WITH A WARM LAYER NEAR 450 MB EVIDENT ON THE 00Z PSR
SOUNDING. LATEST RADAR SHOWS LITTLE IN THE WAY OF SHOWER AND
THUNDERSTORM ACTIVITY...EXCEPT FOR SCATTERED CELLS ACROSS THE HIGHER
TERRAIN WELL EAST OF PHOENIX. FLOOD WATCH HAS BEEN CANCELLED FOR ALL
AREAS EXCEPT FOR AZZ024.
FOR THE REMAINDER OF TONIGHT...ISOLATED ACTIVITY FORCED BY A
WELL-DEFINED VORT MAX ACROSS EAST-CENTRAL AZ WILL PERSIST ACROSS
SOUTHERN GILA COUNTY. THIS WILL LIKELY TRIGGER ADDITIONAL CELLS
FURTHER WEST...PERHAPS INTO EASTERN MARICOPA AND PINAL
COUNTIES...THOUGH ALL HI-RES GUIDANCE INCLUDING THE HRRR INDICATES
THAT STORMS WILL BE ON A DOWNWARD TREND THROUGH MIDNIGHT. LATEST WV
IMAGERY ALSO SHOWS A WELL-FORMED MCS NEAR LAKE HAVASU WHICH SUGGESTS
THE POTENTIAL FOR GRAVITY WAVE PROPAGATION INTO EASTERN RIVERSIDE
COUNTY AND JTNP. DEWPOINTS AS HIGH AS THE UPPER 70S PERSIST ACROSS
SE CA AND ADDITIONAL CONVECTION CANNOT BE RULED OUT OVERNIGHT IN
THESE AREAS. POPS WERE LOWERED THROUGH MORNING BUT REMAIN
CONSIDERABLY ABOVE CLIMO.
&&
.PREVIOUS DISCUSSION...
FRIDAY SHOULD ALSO BE AN ACTIVE DAY WITH LITTLE TO NO CHANGE IN
AIRMASS CONDITIONS AND MODELS INDICATE THE SHORTWAVE NOW OVER NEW
MEXICO SLIDES WESTWARD INTO CENTRAL ARIZONA LATE TONIGHT INTO FRIDAY
MORNING. THE COVERAGE OF STORMS ON FRIDAY WILL LIKELY AGAIN DEPEND
ON THE AMOUNT OF INSOLATION...BUT AREAWIDE PWATS OF 1.75 TO 2 INCHES
SHOULD ALLOW FOR SOME LOCALIZED HEAVY RAINFALL AND FLOODING.
THE TROPICAL MOISTURE FEED WILL GRADUALLY SHIFT TO THE SOUTHWEST
THIS WEEKEND ALLOWING FOR A GRADUAL DECREASE IN MOISTURE ACROSS THE
DESERT SOUTHWEST. BOTH THE GFS AND EUROPEAN INDICATE SOME SORT OF
LINGERING INVERTED TROUGH ACROSS THE NORTHERN HALF OF
ARIZONA...ALLOWING FOR MUCH OF THE MONSOON ACTIVITY TO BE FOCUSED
ALONG THE MOGOLLON RIM AND HIGHER TERRAIN LOCATIONS OF EASTERN
ARIZONA. STILL EXPECTING MONSOON ACTIVITY ACROSS SOUTHERN ARIZONA TO
BE SOMEWHAT ACTIVE...BUT WILL MOSTLY BE RELIANT ON OUTFLOWS FOR
DEVELOPMENT ACROSS THE LOWER DESERTS. A GRADUAL DECREASE IN POPS IS
IN THE FORECAST FOR SATURDAY WITH SLIGHT CHANCE POPS FURTHER WEST
AND CHANCE POPS ACROSS MUCH OF SOUTH-CENTRAL ARIZONA. SUNDAY SHOULD
SEE EVEN LESS STORM CHANCES ACROSS SOUTHEAST CALIFORNIA AND
SOUTHWEST ARIZONA AS DRY AIR STARTS TO FILTER IN FROM THE WEST...BUT
CHANCE POPS IS AGAIN EXPECTED ACROSS SOUTH-CENTRAL ARIZONA.
TEMPERATURES WILL GRADUALLY WARM UP THIS WEEKEND WITH LOWER DESERT
HIGHS NEAR 100 BOTH DAYS.
NEXT WEEK IS SHAPING UP TO BE A TRANSITION FROM A SEMI-ACTIVE TO
NEAR NORMAL MONSOON PERIOD ON MONDAY AND TUESDAY TO DRIER AND WARMER
CONDITIONS FOR THE LATER PART OF NEXT WEEK. LONG RANGE MODELS SHOW
THE SUB-TROPICAL HIGH CENTERING ITSELF OVER COLORADO AND HEIGHTS
BUILDING ACROSS THE REGION. BY LATE NEXT WEEK...HIGH TEMPERATURES
COULD BE TOPPING OUT IN THE 105-108 RANGE ACROSS THE LOWER
DESERTS.
&&
.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA...INCLUDING KPHX...KIWA...KSDL...KIPL...AND KBLH...
ABUNDANT MOISTURE AVAILABLE FOR SHOWERS TO OCCUR JUST ABOUT
ANYWHERE. HOWEVER...AREAS WHERE MORE SUNSHINE REACHES THE GROUND
WILL HAVE BETTER INSTABILITY. AS OF 18Z THOSE AREAS WOULD INCLUDE
NORTHWEST MARICOPA COUNTY...LA PAZ COUNTY...AND YUMA COUNTY. AN
ADDITIONAL FACTOR FOR SHWR/TSTM PRODUCTION WILL BE A CIRCULATION
CENTERED NEAR NORTHERN BAJA MEXICO. MODELS INDICATE A SWATH OF
ENHANCED LIFT FOR THIS AFTERNOON AND EVENING...ASSOCIATED WITH THE
BAJA FEATURE...ACROSS SOUTHWEST MARICOPA COUNTY...YUMA COUNTY...AND
IMPERIAL COUNTY. FOR THE ABOVE REASONS...INCLUDED TEMPO SHWRS/TSTMS
IN THE TAFS. EVEN WITHOUT A FULL FLEDGED TSTM...CEILINGS AND
VISIBILITY WILL BE LOWERED SUBSTANTIALLY BY ANY RAIN SHOWERS. OF
NOTE...THERE IS CONSIDERABLE UNCERTAINTY IN THE TIMING AND EXTENT OF
THE ABOVE MENTIONED FACTORS INFLUENCING THE CONVECTION. WINDS WILL
FAVOR SOUTHWEST DIRECTIONS OVER THE PHOENIX AREA AND SOUTH/SOUTHEAST
DIRECTIONS OVER SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
TROPICAL MOISTURE WILL GRADUALLY DIMINISH SATURDAY THROUGH THE
MIDDLE OF NEXT WEEK...AS MONSOON CONDITIONS RETURN TO CLIMATIC
NORMALS. BELOW SEASONAL NORMAL HIGH TEMPERATURES SATURDAY WILL
STEADILY CLIMB AND REACH TO NORMAL VALUES BY ABOUT TUESDAY...AND
ELEVATED HUMIDITIES SATURDAY WILL GRADUALLY LOWER DAY TO DAY...
FINALLY FALLING INTO THE TEENS BY NEXT WEDNESDAY. WINDS WILL
GENERALLY FOLLOW NORMAL DIURNAL TENDENCIES WITH TYPICAL AFTERNOON
AND EARLY EVENING GUSTINESS...ESPECIALLY OVER FAVORED HIGHER TERRAIN
LOCATIONS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...FLASH FLOOD WATCH UNTIL 11 PM MST THIS EVENING AZZ024.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...KUHLMAN
AVIATION...AJ
FIRE WEATHER...CB
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1015 PM MDT THU AUG 29 2013
.SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT)
ISSUED AT 242 PM MDT THU AUG 29 2013
SHOWERS AND STORMS DEVELOPED AS EXPECTED AROUND 18Z OVER THE FAVORED
HIGHER TERRAIN AREAS PARTICULARLY THE ABAJOS...SAN JUANS...AND
FLATTOPS. THE 12Z GJT SOUNDING SHOWED PW VALUES OF 0.95 INCHES
WHICH IS MATCHING UP QUITE WELL WITH THE RAP AND THE NAM MODELS.
THE GFS PWATS WERE MUCH LOWER SO THINKING THE GFS IS UNDERPLAYING
THE AMT OF MOISTURE. WITH HIGH PRESSURE OVERHEAD...LIGHT STEERING
FLOW WILL LEAD TO STORMS STAYING RELATIVELY ANCHORED TO THE
TERRAIN WITH LITTLE MOVEMENT. SIMILAR PATTERN TO YESTERDAY...SO
EXPECT MUCH OF THE SAME WITH CONVECTION ENDING SHORTLY AFTER
SUNSET AND SOME STORMS LINGERING TILL MIDNIGHT. BIGGEST CONCERN
FOR THE REST OF THIS AFTERNOON INTO THE EVENING IS ANY STORMS THAT
FORM OVER ALREADY SATURATED AREAS...ESPECIALLY THE SAN JUANS WHERE
FLOODING OCCURRED YESTERDAY IN OURAY AND OVER RED MOUNTAIN PASS.
THE 12Z NAM SEEMS TO BE HANDLING THE MOISTURE BETTER THAN THE GFS SO
LEANING TOWARDS IT FOR FRIDAY. PW VALUES STAY RELATIVELY THE SAME
AT 0.9 INCHES ACROSS MUCH OF WESTERN COLORADO. HOWEVER PWATS
INCREASE SOME OVER SE UTAH...WITH SOME OF THE DEEPER MOISTURE
ASSOCIATED WITH THE INVERTED TROUGH OVER AZ AND SOCAL CREEPING INTO
SE UTAH WHERE PWATS INCREASE TO A LITTLE OVER AN INCH. AN ACTIVE
NORTHERN STREAM CAUSES THE RIDGE TO FLATTEN A LITTLE WHICH LAYS A
55KT JET MAX OVER THE CO-WY BORDER. IN ADDITION TO THIS...850-700MB
STREAMLINES SHOW A LOW LEVEL CONVERGENCE SIGNATURE THAT MOVES
THROUGH SE UTAH AND SW COLORADO FRIDAY AFTERNOON...WITH UPPER LEVEL
DIVERGENCE AS INDICATED IN DIVQ FIELDS. THINKING THAT FRIDAY MAY BE
A LITTLE MORE ACTIVE AND WIDESPREAD IN TERMS OF CONVECTION AS THERE
IS SOME LOW LEVEL AND UPPER LEVEL SUPPORT AND SEVERAL STRONG VORT
MAXES THAT MOVE THROUGH THE FLOW THAT CAN ACT AS A TRIGGER ON THE
MOISTURE. THINK THERE WILL BE ENOUGH SFC HEATING TO GET THINGS
GOING AGAIN AS SKIES BEGIN RELATIVELY CLEAR FRIDAY MORNING.
CONVECTION WILL BEGIN FRIDAY AFTERNOON OVER THE HIGHER TERRAIN WITH
SOME STORMS FORMING OVER THE VALLEYS LATER IN THE DAY AS
DISTURBANCES AND BOUNDARIES INTERACT GIVEN THE ADDITIONAL FORCING.
THINGS SHOULD WIND DOWN AFTER SUNSET AGAIN WITH SOME STORMS
LINGERING UNTIL MIDNIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 242 PM MDT THU AUG 29 2013
THE UPPER RIDGE STAYS CENTERED OVER THE FOUR CORNERS ON SATURDAY FOR
ANOTHER DAY OF MAINLY AFTERNOON THUNDERSTORMS OVER ELEVATED
LOCATIONS AS SUFFICIENT 0.60 TO 1.00 PWATS REMAIN TRAPPED UNDER
THE RIDGE...WITH THE DRIEST IN NORTHERN AREAS. THINKING THAT THE
NORTHERN UT/CO BORDER WILL SEE SOME BETTER ORGANIZED/LONGER LIVING
STORMS DESPITE THE LOWER BUT STILL GOOD ENOUGH AVAILABLE MOISTURE
SATURDAY AS THE MODELS INDICATE A MODERATE 40-50 KT SPEED MAX AT
250 MB. SE UTAH AND THE SAN JUANS OF COLORADO WILL REMAIN THE MOST
LIKELY LOCATION FOR STORM DEVELOPMENT WITH HEAVY RAIN AS THE
BIGGEST THREAT. IN SOUTHERN AREAS WITH LOW SHEER...CELLS WILL LIKELY BE
SHORT-LIVED BUT COULD CAUSE INTENSE HEAVY RAINFALL IN LOCALIZED
AREAS WITHIN A SHORT PERIOD OF TIME. A FEW OF THESE STORMS MAY
SURVIVE PAST SUNSET BUT OTHERWISE ARE EXPECTED TO DIMINISH AFTER
DARK. A VORT MAX AXIS WILL LIE NW TO SE ACROSS OUR AREA AND HELP
WITH STORM DEVELOPMENT AS WELL.
DISCREPANCY OVER THE WEEKEND ON THE AMOUNT OF MOISTURE WHICH WILL
REMAIN AVAILABLE BUT OVERALL TRENDS ARE SHOWING A SIMILAR
PATTERN.
SUNDAY IS EXPECTED TO BE SLIGHTLY DRIER UP ALONG THE WYOMING
BORDER WITH OUR CWA DUE TO DRY AIR ADVECTION KICKING INTO THE
REGION FROM THE NORTHWEST AND MINIMAL FORCING ALOFT...THEREFORE POPS
ARE AMPLIFIED TO THE SOUTHERN HALF OF OUR AREA. THIS IS NOT
EXPECTED TO LAST LONG AND WILL LIKELY KEEP A SECTION OF THE
NORTHERN REGION RAIN-FREE ON SUNDAY. ELSEWHERE...ESPECIALLY DOWN
IN THE SAN JUANS...ABAJOS...AND LA SALS...THE ATMOSPHERE WILL
REMAIN JUICY AND ALLOW FOR STRONG DIURNAL TSTORMS IN THE AFTERNOON.
MONDAY THROUGH WEDNESDAY...UPPER LEVEL HIGH PRESSURE STAYS POSITIONED
OVER COLORADO THROUGHOUT THE PERIOD. MONSOONAL MOISTURE CONTINUES
TO STREAM AROUND THE WRN PERIPHERY OF THE HIGH ALLOWING FOR DAILY
STORM INITIATION. SHORTWAVE ON TUESDAY SLICING THROUGH THE CENTER
OF THE HIGH PRESSURE WILL ALLOW FOR ENHANCED ACTIVITY ASSUMING
SKIES REMAIN FAIRLY CLEAR DURING THE FIRST HALF OF THE DAY.
THURSDAY COULD GET INTERESTING...BUT THIS FAR OUT THERE IS VERY
LOW CONFIDENCE IN THE LONG TERM MODELS...ESPECIALLY WITH TWO VERY
DIFFERENT SOLUTIONS. THE GFS IS PROGGING A STRONG PACIFIC LOW TO
DROP DOWN INTO THE INTERMOUNTAIN WEST THURSDAY SWIPING WITHIN NEAR
REACH OF THE REGION...FILTERING UNSEASONALLY COOL AIR INTO NORTHERN
BREACHES OF THE CWA. THE EURO KEEPS THIS FEATURE ALONG THE
NORTHERN ROCKIES WITHOUT MUCH INTERACTION WITH COLORADO AND UTAH.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1015 PM MDT THU AUG 29 2013
VFR CONDITIONS WILL CONTINUE AT ALL TAFS SITES OVERNIGHT.
SCATTERED SHOWERS WILL SLOWLY DISSIPATE OVER THE CENTRAL CO
MOUNTAINS IN THE KASE AND VAIL PASS VICINITIES...WITH LOCAL
MOUNTAIN OBSCURATIONS THROUGH ABOUT 09Z. FRIDAY AFTERNOON ISOLATED
TO SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP AGAIN OVER THE
CO CENTRAL AND SOUTHWEST MOUNTAINS...WITH BRIEF MVFR VSBYS IN
STRONGER RAIN SHOWERS AT KASE...KEGE...KRIL AND KTEX.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...MDA
LONG TERM...JAM
AVIATION...CC
AREA FORECAST DISCUSSION
NWS MIAMI FL
201 AM EDT FRI AUG 30 2013
.AVIATION...
WITH A DRY, WEAK UPPER LEVEL LOW OVER SOUTH FLORIDA, CONDITIONS
WILL BE MOSTLY QUIET FOR ANOTHER DAY, AS MOST CONVECTION WILL BE
INLAND FROM THE TAF SITES. CONDITIONS SHOULD REMAIN VFR TODAY,
ALTHOUGH THERE COULD BE STRAY SHOWER THAT BRIEFLY IMPACTS
CONDITIONS, BUT GIVEN THE LOW CONFIDENCE IN THIS, HAVE KEPT MENTION
OUT OF THE TAFS FOR TODAY. WINDS WILL BE LIGHT AND VARIABLE
THROUGH EARLY AFTERNOON, THEN BECOME SOUTHEAST BETWEEN 5 AND 10
KTS, GOING LIGHT AND VARIABLE ONCE AGAIN THIS EVENING.
&&
.PREV DISCUSSION... /ISSUED 858 PM EDT THU AUG 29 2013/
UPDATE...
A FEW CHANGES WERE MADE TO THE SHORT TERM FORECAST...DUE TO THE
LACK OF ACTIVITY THIS AFTERNOON AND EVENING. THE ONLY AREA THAT
REMAINED ACTIVE WITH SOME SHOWERS AND THUNDERSTORMS WAS AROUND THE
LAKE...AND NOW A FEW SHOWERS DEVELOPED FROM OUTFLOW BOUNDARIES
COLLISIONS ACROSS INTERIOR MIAMI-DADE COUNTY. ALL THIS ACTIVITY
WILL DISSIPATE QUICKLY AS THE NIGHT PROGRESSES. CURRENT GUIDANCE
CONTINUES SHOWING THE STALLED UPPER LEVEL LOW OVER THE WESTERN
HALF OF SOUTH FLORIDA THROUGH THE WEEKEND. THEREFORE...SIMILAR
WEATHER CONDITIONS ARE EXPECTED THROUGH THE HOLIDAY WEEKEND.
PREV DISCUSSION... /ISSUED 308 PM EDT THU AUG 29 2013/
SYNOPSIS...
A WEAK SURFACE HIGH PRESSURE SYSTEM ACROSS THE AREA WILL PERSIST
THROUGH THE WEEKEND AS A LOW PRESSURE TROUGH NORTH OF THE AREA
WEAKENS THROUGH THE PERIOD.
SHORT TERM...THROUGH SATURDAY NIGHT.
UPPER LEVEL LOW ACROSS THE AREA HAS WEAKENED SINCE YESTERDAY
SQUEEZED BETWEEN A STRONG UPPER LEVEL RIDGE ACROSS THE MIDDLE PART
OF THE COUNTRY AND ANOTHER ONE JUST EAST OF THE BAHAMAS. THE LOW
ITSELF IS AT THE TAIL END OF AN UPPER LEVEL TROUGH OFF THE EAST
COAST OF THE US. SHORT RANGE MODEL CONSENSUS INDICATE THIS
FEATURE, AS WEAK AS IT IS, WILL DRIFT SOUTHWEST OVER THE NEXT DAY
OR SO AND THEM MOVE NORTH OF THE AREA BY LATE IN THE WEEKEND. THE
COMBINATION OF DRIER AIR WRAPPED AROUND THIS LOW ALONG WITH UPR
LEVEL CONVERGENCE AND FAIRLY UNIMPRESSIVE THERMODYNAMIC PROFILES
HAVE RESULTED IN SUPPRESSED CONVECTIVE ACTIVITY WITH THIS FEATURE.
NORMALLY IN THE SUMMER TIME THE INTRUSION OF THIS KIND OF FEATURE
WITH COOLER MID LEVEL TEMPS RESULTS IN FAIRLY ACTIVE CONVECTION.
FOR THE REST OF TODAY WE ARE STILL FORECASTING A CHANCE OF SHOWERS
AND STORMS BUT SOMEWHAT LIMITED IN COVERAGE. THERE IS STILL AN OFF
CHANCE OF A STRONG STORM WITH MAIN CONCERN BEING GUSTY WINDS AND
LIGHTNING. THIS IS CONSISTENT WITH BOTH HRRR AND LOCAL HIGH RES
MODELS.
FOR THE REMAINDER OF THE PERIOD THERE IS FAIRLY GOOD CONSENSUS
WITH UPR LEVEL RIDGE ACROSS THE MIDDLE SECTIONS OF THE COUNTRY
RETROGRADING AS AFOREMENTIONED UPPER LEVEL LOW MOVES WEST
SOUTHWEST. ALONG WITH THAT GLOBAL AND HIGH RES MODELS KEEP PWAT
LEVELS AROUND OR BELOW NORMAL. WITH FAIRLY UNIMPRESSIVE
THERMODYNAMIC PROFILES THIS CALLS FOR PERSISTENCE FOR NEXT COUPLE
DAYS WITH ROUTINE DIURNAL CONVECTION IN THE FORM OF SCATTERED
SHOWERS AND STORMS. GIVEN FAIRLY WEAK STORM MOTION VECTORS THERE
ARE ABOUT EQUAL CHANCES OF RAIN ON BOTH SOUTHWEST AND SOUTHEAST
FLORIDA WITH EMPHASIS ACROSS INTERIOR AS SEA AND LAKE BREEZES
REMAIN DOMINANT.
LONG TERM...SUNDAY THROUGH NEXT THURSDAY
WITH UPPER LEVEL LOW OUT OF THE AREA AND LARGE SCALE PATTERN WITH
RIDGING ON THE WEST, TROUGH ON THE EAST, AND RIDGE OF HIGH PRESSURE
AT LOW LEVELS PERSISTING ACROSS THE AREA A PERSISTENT PATTERN OF
DIURNAL SHOWERS AND THUNDERSTORMS IS FORECAST FOR THE ENTIRE
PERIOD WITH NO HIGHLIGHTS AT THIS TIME. TEMPS WILL REMAIN AROUND
NORMAL EXCEPT OVERNIGHT LOWS SLIGHTLY ABOVE NORMAL.
MARINE...
WITH RIDGE OF HIGH PRESSURE AT THE SURFACE IN CONTROL ACROSS THE
AREA THROUGH THE NEXT 5 DAYS OR SO WINDS ARE FORECAST TO REMAIN
BELOW 10 TO 15 KNOTS RANGE THROUGH THE PERIOD. SEAS ARE NOT
FORECAST TO EXCEED 1-3 FEET ACROSS THE ATLANTIC WATERS AND
GENERALLY LESS THAN 2 FEET ACROSS THE GULF WATERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 90 75 90 78 / 30 20 30 20
FORT LAUDERDALE 91 78 90 81 / 30 20 30 20
MIAMI 92 77 90 79 / 30 20 30 20
NAPLES 91 74 90 75 / 30 20 30 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...17/ERA
AVIATION/RADAR...13/SI
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
331 AM CDT FRI AUG 30 2013
.DISCUSSION...
942 PM CDT
THE MAIN CHANGE TO THE GOING FORECAST WAS TO STRESS THE FOG A BIT
MORE OVERNIGHT INTO EARLY FRIDAY MORNING...ESPECIALLY FOR THE
SOUTHEAST HALF OF THE FORECAST AREA...AND ONCE AGAIN ALONG THE
LAKE MI SHORE NAMELY FOR OVERNIGHT.
THE BROAD AREA OF HIGH PRESSURE CENTERED TO OUR EAST CONTINUES TO
EVOLVE ITS WAY SOUTHEAST TOWARD THE MID-ATLANTIC. EARLIER FOG OVER
THE LAKEFRONT INCLUDING IN DOWNTOWN HAD BASICALLY DISSIPATED BY
7-7:30 PM. HOWEVER LATEST GOES FOG PRODUCT IS INDICATING A
RE-BLOSSOMING START OF FOG AND/OR STRATUS EAST OF CHICAGO ABOUT 25
MILES EAST OF CHICAGO. THE BOUNDARY LAYER HAS BEEN ABLE TO
DECOUPLE PER AMDAR SOUNDINGS AND SURFACE WIND OBS. LINGERING HIGH
DEW POINTS NEAR 70 AND LOW-LEVEL MIXING RATIOS AROUND 15 G/KG ARE
DRAPED ACROSS THE SOUTHERN AND WESTERN FORECAST AREA AND CLEAR
SKIES HAVE ALLOWED TEMPERATURES TO GET WITHIN A FEW DEGREES OF
THIS ALREADY AT A HANDFUL OF LOCATIONS.
WHILE THE PRESSURE GRADIENT WILL GRADUALLY BUILD IN FROM THE WEST
TONIGHT...MUCH OF THE EASTERN CWA SHOULD REMAIN DECOUPLED ENOUGH
FOR SURFACE WINDS TO REMAIN CALM. MODIFIED 00Z ILX SOUNDING AND
MODIFIED FORECAST SOUNDINGS FROM THE RAP AND NAM FOR CURRENT
CONDITIONS AT IKK/VPZ INDICATE PROFILES FAVORABLE FOR FOG BY
MIDNIGHT. HAVE BUMPED UP COVERAGE TO AREAS BUT THINK ANY DENSE FOG
WILL REMAIN PATCHY. AS FOR OVER THE LAKE...THE EXPANDING AREA EAST
OF CHICAGO WILL LIKELY ADVECT TOWARD THE IL SHORE AND POSSIBLY
EXPAND BACK TOWARD IN BEFORE THE RETURN FLOW SETTLES IN OVER THE
LAKE AFTER MIDNIGHT. GIVEN WHAT WAS SEEN EARLIER THURSDAY...SOME
OF THIS FOG COULD BE DENSE AS IT ROLLS INTO THE IL SHORE OVERNIGHT.
HAVE MADE ONLY SLIGHT TWEAKS TO MIN TEMPERATURES...WHICH PRIMARILY
LOOK ON TRACK.
EARLY LOOK AT 00Z NAM CONTINUES TO SHOW THE LIKELIHOOD OF
SCATTERED CONVECTION ON FRI AFTERNOON THROUGH ESPECIALLY MID-
EVE...WITH GREATEST CHANCES IN NORTHEAST IL/NORTHWEST
IN...INCLUDING ALL OF CHICAGOLAND. HIGH CAPE/MODEST SHEAR
ENVIRONMENT...ALONG WITH A SLIGHTLY MORE FAVORABLE VORT PATH THAN
PREV RUN...WOULD ALL STILL SUPPORT AN ISOLATED SEVERE THREAT.
MTF
//PREV DISCUSSION...
309 PM CDT
THE MAIN FORECAST CONCERNS WILL BE THE CHANCES AND TIMING OF
THUNDERSTORM ACTIVITY LATE FRIDAY AND FRIDAY NIGHT. TEMPERATURES ARE
ALSO A SIGNIFICANT FOCUS AS IT APPEARS WE WILL BE ON A SEE SAW OVER
THE NEXT SEVERAL DAYS AS SEVERAL COLD FRONTS TAKE AIM ON THE AREA.
THE LAST BIT OF LOW CLOUDS FROM THIS MORNING ARE FINALLY
DISSIPATING JUST WEST OF KPNT EARLY THIS AFTERNOON...SETTING UP
MOSTLY SUNNY SKIES ACROSS THE REGION. HOWEVER...LOW CLOUDS AND FOG
CONTINUE TO FESTER ACROSS THE SOUTHEASTERN TIP OF LAKE
MICHIGAN...JUST OFF THE COOK COUNTY ILLINOIS AND LAKE AND PORTER
COUNTY INDIANA SHORES. ALTHOUGH THIS ACTIVITY HAS REMAINED MAINLY
OVER THE WATERS OF LAKE MICHIGAN THROUGH THE DAY...IT IS POSSIBLY
THAT SOME OF THIS FOG COULD ROLL IN ACROSS THE SHORES EARLY THIS
EVENING. THEREFORE...I ADDED THE MENTION OF AREAS OF FOG FOR THE
IMMEDIATE SHORE LINE. IF THIS FOG DOES MOVE ONSHORE...IT WILL LIKELY
BE DENSE...SO CONDITIONS WILL NEED TO BE MONITORED THIS EVENING. THE
GOOD NEWS IS THAT THE WINDS SHOULD SWITCH OUT OF THE SOUTH OVERNIGHT
TONIGHT...WHICH SHOULD ALLOW ANY FOG TO MOVE BACK OUT OVER THE LAKE
LATER TONIGHT.
THE MAIN WEATHER DISTURBANCE OF INTEREST LATER FRIDAY/FRIDAY
NIGHT...IS CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING ACROSS
NORTH DAKOTA...ALONG THE NORTHERN PERIPHERY OF THE UPPER RIDGE
ENCOMPASSING THE PLAINS. THIS FEATURE IS EXPECTED TO PRODUCE
CONVECTION WELL NORTH OF THE AREA TONIGHT. HOWEVER...A SURFACE COLD
FRONT IS FORECAST TO DROP SOUTHWARD ACROSS WISCONSIN THROUGH THE DAY
ON FRIDAY. TO THE SOUTH OF THIS FRONT...A THERMAL RIDGE WILL SHIFT
EASTWARD ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA....SETTING UP ANOTHER DAY OF HOT AND HUMID CONDITIONS. THIS
SHOULD ALLOW TEMPERATURES TO AGAIN TOP OUT IN THE LOWER TO MIDDLE
90S ACROSS THE AREA ON FRIDAY...WITH HEAT INDICES NEAR 100 DEGREES.
DURING THE LATE AFTERNOON AND EVENING HOURS...THIS COLD FRONT WILL
BEGIN TO MOVE OVER NORTHERN ILLINOIS. IT APPEARS THAT SCATTERED
CONVECTIVE INITIATION WILL OCCUR ACROSS SOUTHERN WISCONSIN BY MID
AFTERNOON...THEN PROGRESS SOUTHEASTWARD ACROSS NORTHERN ILLINOIS
LATER IN THE AFTERNOON AND INTO THE EVENING. IT APPEARS THERE WILL
BE A THREAT FOR SOME STRONG TO SEVERE STORMS WITH THIS ACTIVITY.
HOWEVER...DEEP LAYER SHEAR LOOKS TO REMAIN RATHER MARGINAL (20 TO 30
KT) FOR ORGANIZED CONVECTION. IN SPITE OF THIS...MODEL SOUNDINGS
INDICATE STEEP MID LEVEL LAPS RATES AND PROFILES SUPPORTIVE OF SOME
STRONG WIND GUSTS/MICRO-BURST...SO THE THREAT OF SEVERE STORMS IS NOT
ZERO. IN ADDITION...THE HIGH THETA-E AIR MASS AHEAD OF THE
APPROACHING FRONT...WITH PWATS EXPECTED TO BE AROUND 1.9
INCHES...COULD SUPPORT SOME TORRENTIAL DOWNPOURS IN THE STRONGEST
STORMS. THESE STORMS SHOULD DROP SOUTH AND EASTWARD ACROSS THE AREA
THROUGH THE EVENING. SOME THIS ACTIVITY COULD LINGER OVERNIGHT INTO
EARLY SATURDAY ACROSS MY FAR SOUTHERN COUNTIES.
SOME COOLER AIR ARRIVES ACROSS THE AREA FOR SATURDAY IN THE WAKE OF
THIS FRONTAL ZONE. THIS SHOULD DROP TEMPERATURES BACK INTO THE MID
TO UPPER 80S FOR SATURDAY.
A SECOND SYSTEM LOOKS TO TOP THE RIDGE AXIS ACROSS THE PLAINS...AND
THEN DIG SOUTHEASTWARD OVER THE GREAT LAKES LATE SUNDAY AND INTO
MONDAY. THIS SYSTEM LOOKS TO DRIVE ANOTHER...STRONGER COLD FRONT
ACROSS THE AREA DURING THE DAY ON SUNDAY. THIS APPEARS TO BE ANOTHER
DECENT SHOT FOR SOME SHOWERS AND THUNDERSTORMS INTO SUNDAY EVENING.
ONCE THIS FRONT PASSES BY...MUCH COOLER AND DRIER AIR WILL MOVE
ACROSS THE AREA FOR MONDAY AS A SURFACE HIGH BUILDS EASTWARD ACROSS
THE MID MISSISSIPPI RIVER VALLEY. THIS SHOULD RESULT IN HIGHS BACK
INTO THE 70S FOR MONDAY AND TUESDAY.
TEMPERATURES LOOK TO MODERATE BACK INTO THE 80S BY WEDNESDAY AS THE
THERMAL RIDGE SHIFTS EASTWARD ALONG THE BACK SIDE OF THE SURFACE
HIGH. HOWEVER...THE OVERALL PATTERN LOOKS TO REMAIN DRY ACROSS THE
REGION THROUGH THE MIDDLE OF NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* PSBL HIGH END MVFR VIS BR/HZ THRU DAYBREAK.
* SOUTHWEST WINDS SLOWLY INCREASING WITH GUSTS TO 20 KT AFT 15Z.
* PSBL TSRA DEVELOPING AFT 18Z...LINGERING VCSH THRU 00Z SAT.
BEACHLER
//DISCUSSION...UPDATED 06Z...
VERY WARM AND MOIST AIRMASS REMAINS IN PLACE...WITH VERY LITTLE
WIND OVERNIGHT. THIS WILL ALLOW MANY AREAS TO BEGIN SEEING A
REDUCTION TO VSBYS WITH 3-5SM AND BR/HZ CONDITIONS. AT THIS TIME
IT APPEARS MOST TAF SITES WILL REMAIN VFR...WITH THE EXCEPTION OF
GYY THAT HAS ALREADY SEEN VSBYS OF 4SM. JUST AFT DAYBREAK WINDS
WILL INCREASE FROM THE SOUTHWEST WITH HEATING ALLOWING FOR MIXING
AND GUSTS UP TO 20KT. THEN THE FOCUS TURNS TOWARDS DEVELOPMENT OF
SHRA/TSRA AFT 18Z. GUIDANCE IS BEGINNING TO POINT TOWARDS A
SLIGHTLY EARLIER DEVELOPMENT TO THE CONVECTION...AND HAVE PUSHED
UP THE TIME OF THE PROB30 GROUP TO ACCOUNT FOR THIS. THE FRONTAL
BOUNDARY THAT WILL APPROACH THE REGION DOES APPEAR TO SLOW THIS
EVENING...WHICH COULD TRANSLATE INTO A LONGER PERIOD OF SHRA/TSRA.
IN ADDITION WITH A LIGHT GRADIENT AHEAD OF THE FRONTAL
PASSAGE...REDUCTION TO VSBY/CIGS WILL LIKELY OCCUR AFT 00Z.
CURRENT THINKING IS THAT CIGS WILL NEAR LOW END MVFR CONDS...UNTIL
FRONTAL PASSAGE AND SOME DRY AIR FILTERING INTO THE REGION. THEN
CIGS WILL SLOWLY COME BACK UP TO 2-3KFT AGL CLOSER TO DAYBREAK
SAT.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.
* MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPMENT.
* LOW CONFIDENCE IN PRECISE TIME/COVERAGE OF SHRA/TSRA THIS AFTN.
* MEDIUM CONFIDENCE IN REDUCED VSBYS/CIGS AFT 00Z SAT.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY...VFR. WX NIL.
SUNDAY...VFR. CHANCE TSRA AFTERNOON AND NIGHT WHICH COULD PRODUCE
BRIEF LOCAL MVFR/IFR.
MONDAY THROUGH WEDNESDAY. VFR. NO SIG WX.
TRS
&&
.MARINE...
321 AM CDT
A SERIES OF FRONTAL BOUNDARIES WILL TRAVERSE LAKE MICHIGAN OVER
THE NEXT FEW DAYS. PATCHY FOG WILL LINGER THROUGH EARLY THIS
MORNING...AND SHOULD DISSIPATE BY MID MORNING.
FOR TODAY A SOUTHWEST FLOW WILL INCREASE WITH WINDS PUSHING TO 15
TO 25 KT ACROSS THE NORTHERN HALF OF THE LAKE...WHICH WILL QUICKLY
BUILD WAVES FOR THE NORTHERN PORTIONS. THEN A FRONTAL BOUNDARY
WILL STEADILY PUSH SOUTH ACROSS THE LAKE...WITH WINDS VEERING TO
NORTHWEST THEN NORTH. THIS WILL ALLOW A PERIOD OF BETTER FETCH FOR
THE SOUTHERN HALF AND BUILDING WAVES FOR SATURDAY. THE GRADIENT
WILL TIGHTEN BEHIND THE BOUNDARY AND WAVES SHOULD EASILY BUILD TO
4 TO 6 FT SATURDAY...HOWEVER THIS APPEARS TO BE A NARROW WINDOW AS
HIGH PRESSURE WILL PUSH OVER THE LAKE AND LINGER UNTIL SUNDAY
MORNING. WHICH WILL ALLOW WAVES TO SUBSIDE BRIEFLY SUNDAY. THEN
ANOTHER COLD FRONT WILL ARRIVE SUNDAY NIGHT...WHICH WILL BRING
COOLER AIR OF THE WARMER LAKE FOR MONDAY. THE RESULT WILL LIKELY
BE A PERIOD OF GUSTY WINDS...WITH BUILDING WAVES FOR MONDAY. BASED
ON THE CURRENT FORECAST...MONDAY COULD PRODUCE SMALL CRAFT
HEADLINES FOR THE ILLINOIS/INDIANA NEARSHORE WATERS AS WINDS WILL
BE NORTHERLY FOR A PROLONGED PERIOD AND GUSTY...ALONG WITH THE
COOLER AIR FLOWING OVER THE WARMER LAKE.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1256 AM CDT FRI AUG 30 2013
.DISCUSSION...
942 PM CDT
THE MAIN CHANGE TO THE GOING FORECAST WAS TO STRESS THE FOG A BIT
MORE OVERNIGHT INTO EARLY FRIDAY MORNING...ESPECIALLY FOR THE
SOUTHEAST HALF OF THE FORECAST AREA...AND ONCE AGAIN ALONG THE
LAKE MI SHORE NAMELY FOR OVERNIGHT.
THE BROAD AREA OF HIGH PRESSURE CENTERED TO OUR EAST CONTINUES TO
EVOLVE ITS WAY SOUTHEAST TOWARD THE MID-ATLANTIC. EARLIER FOG OVER
THE LAKEFRONT INCLUDING IN DOWNTOWN HAD BASICALLY DISSIPATED BY
7-7:30 PM. HOWEVER LATEST GOES FOG PRODUCT IS INDICATING A
RE-BLOSSOMING START OF FOG AND/OR STRATUS EAST OF CHICAGO ABOUT 25
MILES EAST OF CHICAGO. THE BOUNDARY LAYER HAS BEEN ABLE TO
DECOUPLE PER AMDAR SOUNDINGS AND SURFACE WIND OBS. LINGERING HIGH
DEW POINTS NEAR 70 AND LOW-LEVEL MIXING RATIOS AROUND 15 G/KG ARE
DRAPED ACROSS THE SOUTHERN AND WESTERN FORECAST AREA AND CLEAR
SKIES HAVE ALLOWED TEMPERATURES TO GET WITHIN A FEW DEGREES OF
THIS ALREADY AT A HANDFUL OF LOCATIONS.
WHILE THE PRESSURE GRADIENT WILL GRADUALLY BUILD IN FROM THE WEST
TONIGHT...MUCH OF THE EASTERN CWA SHOULD REMAIN DECOUPLED ENOUGH
FOR SURFACE WINDS TO REMAIN CALM. MODIFIED 00Z ILX SOUNDING AND
MODIFIED FORECAST SOUNDINGS FROM THE RAP AND NAM FOR CURRENT
CONDITIONS AT IKK/VPZ INDICATE PROFILES FAVORABLE FOR FOG BY
MIDNIGHT. HAVE BUMPED UP COVERAGE TO AREAS BUT THINK ANY DENSE FOG
WILL REMAIN PATCHY. AS FOR OVER THE LAKE...THE EXPANDING AREA EAST
OF CHICAGO WILL LIKELY ADVECT TOWARD THE IL SHORE AND POSSIBLY
EXPAND BACK TOWARD IN BEFORE THE RETURN FLOW SETTLES IN OVER THE
LAKE AFTER MIDNIGHT. GIVEN WHAT WAS SEEN EARLIER THURSDAY...SOME
OF THIS FOG COULD BE DENSE AS IT ROLLS INTO THE IL SHORE OVERNIGHT.
HAVE MADE ONLY SLIGHT TWEAKS TO MIN TEMPERATURES...WHICH PRIMARILY
LOOK ON TRACK.
EARLY LOOK AT 00Z NAM CONTINUES TO SHOW THE LIKELIHOOD OF
SCATTERED CONVECTION ON FRI AFTERNOON THROUGH ESPECIALLY MID-
EVE...WITH GREATEST CHANCES IN NORTHEAST IL/NORTHWEST
IN...INCLUDING ALL OF CHICAGOLAND. HIGH CAPE/MODEST SHEAR
ENVIRONMENT...ALONG WITH A SLIGHTLY MORE FAVORABLE VORT PATH THAN
PREV RUN...WOULD ALL STILL SUPPORT AN ISOLATED SEVERE THREAT.
MTF
//PREV DISCUSSION...
309 PM CDT
THE MAIN FORECAST CONCERNS WILL BE THE CHANCES AND TIMING OF
THUNDERSTORM ACTIVITY LATE FRIDAY AND FRIDAY NIGHT. TEMPERATURES ARE
ALSO A SIGNIFICANT FOCUS AS IT APPEARS WE WILL BE ON A SEE SAW OVER
THE NEXT SEVERAL DAYS AS SEVERAL COLD FRONTS TAKE AIM ON THE AREA.
THE LAST BIT OF LOW CLOUDS FROM THIS MORNING ARE FINALLY
DISSIPATING JUST WEST OF KPNT EARLY THIS AFTERNOON...SETTING UP
MOSTLY SUNNY SKIES ACROSS THE REGION. HOWEVER...LOW CLOUDS AND FOG
CONTINUE TO FESTER ACROSS THE SOUTHEASTERN TIP OF LAKE
MICHIGAN...JUST OFF THE COOK COUNTY ILLINOIS AND LAKE AND PORTER
COUNTY INDIANA SHORES. ALTHOUGH THIS ACTIVITY HAS REMAINED MAINLY
OVER THE WATERS OF LAKE MICHIGAN THROUGH THE DAY...IT IS POSSIBLY
THAT SOME OF THIS FOG COULD ROLL IN ACROSS THE SHORES EARLY THIS
EVENING. THEREFORE...I ADDED THE MENTION OF AREAS OF FOG FOR THE
IMMEDIATE SHORE LINE. IF THIS FOG DOES MOVE ONSHORE...IT WILL LIKELY
BE DENSE...SO CONDITIONS WILL NEED TO BE MONITORED THIS EVENING. THE
GOOD NEWS IS THAT THE WINDS SHOULD SWITCH OUT OF THE SOUTH OVERNIGHT
TONIGHT...WHICH SHOULD ALLOW ANY FOG TO MOVE BACK OUT OVER THE LAKE
LATER TONIGHT.
THE MAIN WEATHER DISTURBANCE OF INTEREST LATER FRIDAY/FRIDAY
NIGHT...IS CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING ACROSS
NORTH DAKOTA...ALONG THE NORTHERN PERIPHERY OF THE UPPER RIDGE
ENCOMPASSING THE PLAINS. THIS FEATURE IS EXPECTED TO PRODUCE
CONVECTION WELL NORTH OF THE AREA TONIGHT. HOWEVER...A SURFACE COLD
FRONT IS FORECAST TO DROP SOUTHWARD ACROSS WISCONSIN THROUGH THE DAY
ON FRIDAY. TO THE SOUTH OF THIS FRONT...A THERMAL RIDGE WILL SHIFT
EASTWARD ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA....SETTING UP ANOTHER DAY OF HOT AND HUMID CONDITIONS. THIS
SHOULD ALLOW TEMPERATURES TO AGAIN TOP OUT IN THE LOWER TO MIDDLE
90S ACROSS THE AREA ON FRIDAY...WITH HEAT INDICES NEAR 100 DEGREES.
DURING THE LATE AFTERNOON AND EVENING HOURS...THIS COLD FRONT WILL
BEGIN TO MOVE OVER NORTHERN ILLINOIS. IT APPEARS THAT SCATTERED
CONVECTIVE INITIATION WILL OCCUR ACROSS SOUTHERN WISCONSIN BY MID
AFTERNOON...THEN PROGRESS SOUTHEASTWARD ACROSS NORTHERN ILLINOIS
LATER IN THE AFTERNOON AND INTO THE EVENING. IT APPEARS THERE WILL
BE A THREAT FOR SOME STRONG TO SEVERE STORMS WITH THIS ACTIVITY.
HOWEVER...DEEP LAYER SHEAR LOOKS TO REMAIN RATHER MARGINAL (20 TO 30
KT) FOR ORGANIZED CONVECTION. IN SPITE OF THIS...MODEL SOUNDINGS
INDICATE STEEP MID LEVEL LAPS RATES AND PROFILES SUPPORTIVE OF SOME
STRONG WIND GUSTS/MICRO-BURST...SO THE THREAT OF SEVERE STORMS IS NOT
ZERO. IN ADDITION...THE HIGH THETA-E AIR MASS AHEAD OF THE
APPROACHING FRONT...WITH PWATS EXPECTED TO BE AROUND 1.9
INCHES...COULD SUPPORT SOME TORRENTIAL DOWNPOURS IN THE STRONGEST
STORMS. THESE STORMS SHOULD DROP SOUTH AND EASTWARD ACROSS THE AREA
THROUGH THE EVENING. SOME THIS ACTIVITY COULD LINGER OVERNIGHT INTO
EARLY SATURDAY ACROSS MY FAR SOUTHERN COUNTIES.
SOME COOLER AIR ARRIVES ACROSS THE AREA FOR SATURDAY IN THE WAKE OF
THIS FRONTAL ZONE. THIS SHOULD DROP TEMPERATURES BACK INTO THE MID
TO UPPER 80S FOR SATURDAY.
A SECOND SYSTEM LOOKS TO TOP THE RIDGE AXIS ACROSS THE PLAINS...AND
THEN DIG SOUTHEASTWARD OVER THE GREAT LAKES LATE SUNDAY AND INTO
MONDAY. THIS SYSTEM LOOKS TO DRIVE ANOTHER...STRONGER COLD FRONT
ACROSS THE AREA DURING THE DAY ON SUNDAY. THIS APPEARS TO BE ANOTHER
DECENT SHOT FOR SOME SHOWERS AND THUNDERSTORMS INTO SUNDAY EVENING.
ONCE THIS FRONT PASSES BY...MUCH COOLER AND DRIER AIR WILL MOVE
ACROSS THE AREA FOR MONDAY AS A SURFACE HIGH BUILDS EASTWARD ACROSS
THE MID MISSISSIPPI RIVER VALLEY. THIS SHOULD RESULT IN HIGHS BACK
INTO THE 70S FOR MONDAY AND TUESDAY.
TEMPERATURES LOOK TO MODERATE BACK INTO THE 80S BY WEDNESDAY AS THE
THERMAL RIDGE SHIFTS EASTWARD ALONG THE BACK SIDE OF THE SURFACE
HIGH. HOWEVER...THE OVERALL PATTERN LOOKS TO REMAIN DRY ACROSS THE
REGION THROUGH THE MIDDLE OF NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* PSBL HIGH END MVFR VIS BR/HZ THRU DAYBREAK.
* SOUTHWEST WINDS SLOWLY INCREASING WITH GUSTS TO 20 KT AFT 15Z.
* PSBL TSRA DEVELOPING AFT 18Z...LINGERING VCSH THRU 00Z SAT.
BEACHLER
//DISCUSSION...UPDATED 06Z...
VERY WARM AND MOIST AIRMASS REMAINS IN PLACE...WITH VERY LITTLE
WIND OVERNIGHT. THIS WILL ALLOW MANY AREAS TO BEGIN SEEING A
REDUCTION TO VSBYS WITH 3-5SM AND BR/HZ CONDITIONS. AT THIS TIME
IT APPEARS MOST TAF SITES WILL REMAIN VFR...WITH THE EXCEPTION OF
GYY THAT HAS ALREADY SEEN VSBYS OF 4SM. JUST AFT DAYBREAK WINDS
WILL INCREASE FROM THE SOUTHWEST WITH HEATING ALLOWING FOR MIXING
AND GUSTS UP TO 20KT. THEN THE FOCUS TURNS TOWARDS DEVELOPMENT OF
SHRA/TSRA AFT 18Z. GUIDANCE IS BEGINNING TO POINT TOWARDS A
SLIGHTLY EARLIER DEVELOPMENT TO THE CONVECTION...AND HAVE PUSHED
UP THE TIME OF THE PROB30 GROUP TO ACCOUNT FOR THIS. THE FRONTAL
BOUNDARY THAT WILL APPROACH THE REGION DOES APPEAR TO SLOW THIS
EVENING...WHICH COULD TRANSLATE INTO A LONGER PERIOD OF SHRA/TSRA.
IN ADDITION WITH A LIGHT GRADIENT AHEAD OF THE FRONTAL
PASSAGE...REDUCTION TO VSBY/CIGS WILL LIKELY OCCUR AFT 00Z.
CURRENT THINKING IS THAT CIGS WILL NEAR LOW END MVFR CONDS...UNTIL
FRONTAL PASSAGE AND SOME DRY AIR FILTERING INTO THE REGION. THEN
CIGS WILL SLOWLY COME BACK UP TO 2-3KFT AGL CLOSER TO DAYBREAK
SAT.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.
* MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPMENT.
* LOW CONFIDENCE IN PRECISE TIME/COVERAGE OF SHRA/TSRA THIS AFTN.
* MEDIUM CONFIDENCE IN REDUCED VSBYS/CIGS AFT 00Z SAT.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY...VFR. WX NIL.
SUNDAY...VFR. CHANCE TSRA AFTERNOON AND NIGHT WHICH COULD PRODUCE
BRIEF LOCAL MVFR/IFR.
MONDAY THROUGH WEDNESDAY. VFR. NO SIG WX.
TRS
&&
.MARINE...
303 PM CDT
HIGH PRESSURE OVER MICHIGAN WILL CONTINUE TO MOVE SOUTHEASTWARD
TONIGHT WHILE LOW PRESSURE MOVES FROM MINNESOTA TO LAKE SUPERIOR.
THE PRESSURE GRADIENT WILL BUILD ACROSS NORTHERN SECTIONS OF THE
LAKE OVERNIGHT AND SPREAD DOWN THE LAKE FRIDAY MORNING. THIS WILL
SUPPORT AND INCREASE IN SOUTHWESTERLY WINDS ACROSS THE LAKE THROUGH
FRIDAY MORNING. ANOTHER CONCERN LINGERING FOG OF SOUTHERN LAKE
MICHIGAN THIS AFTERNOON. HAVE ISSUED A DENSE FOG ADVISORY FOR MOST
OF THE IL/IN NEARSHORE WATERS AND THE FAR SOUTHWEST CORNER OF THE
OPEN WATERS. WITH WINDS REMAINING LIGHT ACROSS THE FAR SOUTH INTO
TONIGHT SO THIS FOG MAY CONTINUE THOUGH IT MAY LIFT TO LOW STRATUS
AROUND THE EDGES INTO EARLY EVENING. LOW CONFIDENCE IN HOW IT
EVOLVES BUT THE PRESSURE GRADIENT ORGANIZES SOMEWHAT THIS EVENING
SO A STEADIER...BUT STILL LIGHT...SOUTH WIND SHOULD RESULT AND MAY
HELP ANY REMAINING VSBY REDUCTIONS TO IMPROVE. A COLD FRONT WILL
DROP SOUTHWARD DOWN THE LAKE FRIDAY AND FRIDAY EVENING TURNING
WINDS NORTHERLY. WEAK HIGH PRESSURE WILL THEN BUILD IN SATURDAY
BRINGING WEAKENING WINDS INTO SATURDAY EVENING. STRONG LOW
PRESSURE WILL THEN MOVE FROM NORTHERN MINNESOTA/WESTERN ONTARIO
ACROSS LAKE SUPERIOR SUNDAY SENDING A COLD FRONT EASTWARD ACROSS
THE LAKE SUNDAY AFTERNOON OR EVENING. STRONG HIGH PRESSURE WILL
MOVE EAST ACROSS THE PLAINS AND MID AND UPPER MISSISSIPPI RIVER
VALLEY MONDAY. THERE WILL BE A STRONG PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS WITH A PUSH OF COOLER AIR SPREADING IN BEHIND THE
FRONT SO WINDS WILL BE INCREASING AS THEY TURN NORTHWEST THEN MORE
NORTHERLY. THE HIGH WILL THEN MOVE ACROSS THE LAKE
TUESDAY/WEDNESDAY BRINGING LIGHT AND VARIABLE WINDS.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS GRAY ME
448 AM EDT FRI AUG 30 2013
.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA
EARLY TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE
SATURDAY BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH
THROUGH NEW ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON
TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATE...MINOR CHANGES TO REFLECT CURRENT OBSERVATIONAL TRENDS.
PREVIOUS DISCUSSION...STRATUS DECK FILLING BACK IN A LITTLE AS
NOCTURNAL COOLING AND WEAK LIFT CONTINUES N OF THE WARM FNT. THIS
SHOULD LIMIT MIN TEMPS THIS MORNING...AND IN FACT RAISE TEMPS A
FEW DEGREES ACROSS ERN AREAS THAT CLEARED OUT EARLIER.
LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE
AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY
AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR
AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH
PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE
NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING
THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND
TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST.
SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE
FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE
AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS.
HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT
MENTIONING IN THE GRIDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS
OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A
FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS
WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF
CLOUDS AND MILD MIN TEMPS.
ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE
AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE
BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER
INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL
SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE
FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY
MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER
VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND
CENTRAL MAINE AND NEW HAMPSHIRE.
THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY.
SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF
THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE
EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY
TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE
REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW
THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST
AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING.
THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR
INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR
DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR
CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR
CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND
SAT.
LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY.
THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN
CEILINGS AND VSBYS.
&&
.MARINE...
SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT.
LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5
FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
LEGRO/JC
AREA FORECAST DISCUSSION
NWS GRAY ME
246 AM EDT FRI AUG 30 2013
.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA
EARLY TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE
SATURDAY BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH
THROUGH NEW ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON
TUESDAY.
&&
.NEAR TERM /THROUGH TODAY/...
STRATUS DECK FILLING BACK IN A LITTLE AS NOCTURNAL COOLING AND
WEAK LIFT CONTINUES N OF THE WARM FNT. THIS SHOULD LIMIT MIN TEMPS
THIS MORNING...AND IN FACT RAISE TEMPS A FEW DEGREES ACROSS ERN
AREAS THAT CLEARED OUT EARLIER.
LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE
AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY
AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR
AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH
PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE
NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING
THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND
TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST.
SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE
FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE
AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS.
HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT
MENTIONING IN THE GRIDS.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM SATURDAY/...
LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS
OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A
FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS
WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF
CLOUDS AND MILD MIN TEMPS.
ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE
AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE
BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER
INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL
SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE
FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY
MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER
VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND
CENTRAL MAINE AND NEW HAMPSHIRE.
THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY.
SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF
THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE
EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY
TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE
REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW
THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST
AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING.
THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR
INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR
DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR
CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR
CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND
SAT.
LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY.
THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN
CEILINGS AND VSBYS.
&&
.MARINE...
SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT.
LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5
FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
LEGRO/JC
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
104 AM CDT FRI AUG 30 2013
.UPDATE...QUICK UPDATE TO LOWER/DROP POPS OVER MN ZONES AND REDUCE
OVER WISC ZONES. NW POST FRONTAL FLOW IS DEEPENING OVER NE MN WITH
DRIER AIR FILTERING INTO THE CWA. OPPORTUNITY STILL EXISTS FOR
REDEVELOPMENT OF CONVECTION OVER WISC WITH PREFRONTAL LIFT AND MID
LVL LAPSE RATES EXCEEDING 7C/KM PER SPC MESOANALYSIS. ALSO HAVE
30/35KT DEEP LAYER SHEAR HOWEVER WITH BDRY LYR
DECOUPLED...ELEVATED CONVECTION SHOULD BE THE RESULT WITH LOCALLY
GUSTY WINDS AND HEAVY DOWNPOURS.
&&
.PREV DISCUSSION... /ISSUED 1239 AM CDT FRI AUG 30 2013/
AVIATION...06Z TAFS.
MOST OF THE CONVECTION HAS ALREADY MOVED THROUGH THE
TERMINALS...WITH THE EXCEPTION OF KHYR...AND THE STORMS SHOULD STAY
AWAY FROM THERE...PASSING TO THE SOUTH. HAVE LEFT IN A VCTS UNTIL
08Z...WHEN THEY SHOULD BE WELL OUT OF THERE. SOME IFR CIGS HAVE SWEPT
INTO THE AREA BEHIND THE STORMS AND THE COLD FRONT. SO FAR THE CIGS
ARE NOT CONSISTENT BUT ARE DOWN IN THE IFR TO LOW END MVFR RANGE
WITH THIS STRATOCUMULUS LAYER. THIS STRATUS AND THE OTHER LOW
CLOUDS AROUND SHOULD CONTINUE UNTIL MID TO LATE MORNING WHEN
MIXING WILL BREAK IT UP. A GRADUAL RETURN TO VFR CIGS EXPECTED BY
15-17Z. WINDS...WHICH WILL HAVE SWITCHED TO NORTHWEST BEHIND THE
FRONT WILL GRADUALLY TURN NORTH AND THEN NORTHEAST AT OR BELOW 10
KTS BY MID DAY FRIDAY...AND THEN DROP OFF TO NORTHEAST LESS THAN
10KTS.
PREV DISCUSSION... /ISSUED 350 PM CDT THU AUG 29 2013/
SHORT TERM...THE MAIN FOCUS FOR TONIGHT IS THUNDERSTORMS.
AT 330 PM...THUNDERSTORMS WERE GENERALLY ON THE DECREASE ACROSS
THE CWA. THE STRONGEST STORM WAS LOCATED OVER IRON COUNTY. THIS
WAS PART OF THE LARGE LINE OF STORMS THAT MOVED FROM THE DAKOTAS
LAST NIGHT...THROUGH NORTHERN MINNESOTA AND NORTHERN WISCONSIN.
TEMPERATURES RANGED FROM THE 60S NEAR LAKE SUPERIOR TO NEAR 90 IN
OUR FAR SOUTHERN COUNTIES. DEWPOINTS WERE LARGELY IN THE 60S NORTH
TO THE 70S SOUTH.
THE MAIN FOCUS FOR TONIGHT WILL DEFINITELY BE THUNDERSTORMS. THE
ATMOSPHERE HAS BEEN WORKED OVER PRETTY WELL FROM THE MCS THAT
MOVED ACROSS MUCH OF THE CWA DURING THE DAY. IT MAY STILL TAKE
SOME TIME BEFORE THINGS DESTABILIZE FURTHER FOR MORE DEVELOPMENT
LATER THIS AFTERNOON AND INTO THE EVENING. THE NMM WRF/NSSL WRF/
HRRR AND RAP NOT DOING THE BEST AS OF 330 PM. THE 4 KM NMM WRF
SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT SCENARIO. THIS MODEL
INDICATES THAT STORMS WILL FIRE UP AGAIN ACROSS NW MN AND SWEEP
FROM NW TO SE ACROSS ESPECIALLY THE SW 1/3 OF THE CWA. THIS WOULD
MAKE THE MOST SENSE AS THIS SHOULD BE THE AREA MOST APT TO
DESTABILIZE AND WITH THE BEST SURFACE CONVERGENCE. MANY OF THE
MODELS ARE ACTUALLY INDICATING THE MOST WIDESPREAD PRECIPITATION
ACROSS NORTHERN PORTIONS OF THE AREA...WHICH WOULD BE WHERE IT HAS
LARGELY STABILIZED THOUGH.
FRIDAY SHOULD BE MUCH MORE QUIET...AS A COLD FRONT BRINGS A BIT
COOLER AND DRIER AIR TO THE REGION. HIGH TEMPERATURES SHOULD STILL
BE IN THE 80S FOR THE MOST PART.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
DRY CONDITIONS ARE EXPECTED FRI NIGHT AND EARLY SAT ACROSS MUCH OF
THE UPPER MIDWEST AS A WEAK RIDGE OF HIGH PRESSURE ALOFT AND A SFC
HIGH DOMINATE THE REGION. THE NEXT SYSTEM WILL DEVELOP OVER THE NRN
PLAINS AND CANADIAN FRONT RANGE FRI NIGHT AND MOVE EWD THROUGH NRN
MN AND INTO WRN ONTARIO DURING THE DAY SAT AND SAT NIGHT. THE MODELS
ARE IN VERY GOOD AGREEMENT BRINGING THE SFC LOW EWD JUST NORTH OF
THE INTERNATIONAL BORDER INTO WRN ONTARIO BY SUNDAY MORNING...WITH A
SFC TROUGH/COLD FRONT EXTENDING SWD THROUGH MN. SHOWERS AND STORMS
ARE EXPECTED TO SPREAD ACROSS THE REGION ALONG AND AHEAD OF THIS
FRONT...WITH A CHANCE OF A FEW STRONG OR SEVERE STORMS. AS THE SFC
LOW TRACKS TO THE EAST INTO CENTRAL ONTARIO AND THE FRONT SLIDES
INTO WI/MICH U.P. A TIGHT PRES GRADIENT WILL SET UP ON THE BACK SIDE
OF THE LOW IN NE MN AND ALLOW GUSTY N WINDS TO DEVELOP WITH A FEW
SUNDAY MORNING AND AFTERNOON CAA RAIN SHOWERS. HIGH PRESSURE WILL
MOVE IN AND DOMINATE THE AREA BY MONDAY AND CONTINUE TO BRING DRY
CONDITIONS TO THE NORTHLAND THROUGH TUE AND INTO EARLY WED. A WEAK
FRONT WILL DROP SWD INTO THE REGION LATE WED AND BRING WITH IT
ADDITIONAL CHANCES FOR SHOWERS.
TEMPERATURES SATURDAY WILL CONTINUE TO BE WARM WITH HIGHS IN THE
UPPER 70S AND LOWER TO MID 80S...ALONG WITH HUMID CONDITIONS.
HOWEVER...THE COLD FRONT ON SATURDAY NIGHT WILL USHER IN A MUCH
DRIER AND COOLER AIR MASS WITH HIGHS ON SUN AND MON IN THE 60S AND
70S...AND NOTICEABLY LOWER HUMIDITIES. TEMPS WARM BA
&&
.POINT TEMPS/POPS...
DLH 80 58 79 61 / 10 0 20 50
INL 84 62 82 57 / 10 20 50 50
BRD 86 62 86 60 / 10 0 40 50
HYR 83 58 84 63 / 20 0 10 60
ASX 78 59 78 63 / 20 0 10 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...CANNON
AREA FORECAST DISCUSSION
NWS DULUTH MN
1239 AM CDT FRI AUG 30 2013
.AVIATION...06Z TAFS.
MOST OF THE CONVECTION HAS ALREADY MOVED THROUGH THE
TERMINALS...WITH THE EXCEPTION OF KHYR...AND THE STORMS SHOULD STAY
AWAY FROM THERE...PASSING TO THE SOUTH. HAVE LEFT IN A VCTS UNTIL
08Z...WHEN THEY SHOULD BE WELL OUT OF THERE. SOME IFR CIGS HAVE SWEPT
INTO THE AREA BEHIND THE STORMS AND THE COLD FRONT. SO FAR THE CIGS
ARE NOT CONSISTENT BUT ARE DOWN IN THE IFR TO LOW END MVFR RANGE
WITH THIS STRATOCUMULUS LAYER. THIS STRATUS AND THE OTHER LOW
CLOUDS AROUND SHOULD CONTINUE UNTIL MID TO LATE MORNING WHEN
MIXING WILL BREAK IT UP. A GRADUAL RETURN TO VFR CIGS EXPECTED BY
15-17Z. WINDS...WHICH WILL HAVE SWITCHED TO NORTHWEST BEHIND THE
FRONT WILL GRADUALLY TURN NORTH AND THEN NORTHEAST AT OR BELOW 10
KTS BY MID DAY FRIDAY...AND THEN DROP OFF TO NORTHEAST LESS THAN
10KTS.
&&
PREV DISCUSSION... /ISSUED 350 PM CDT THU AUG 29 2013/
SHORT TERM...THE MAIN FOCUS FOR TONIGHT IS THUNDERSTORMS.
AT 330 PM...THUNDERSTORMS WERE GENERALLY ON THE DECREASE ACROSS
THE CWA. THE STRONGEST STORM WAS LOCATED OVER IRON COUNTY. THIS
WAS PART OF THE LARGE LINE OF STORMS THAT MOVED FROM THE DAKOTAS
LAST NIGHT...THROUGH NORTHERN MINNESOTA AND NORTHERN WISCONSIN.
TEMPERATURES RANGED FROM THE 60S NEAR LAKE SUPERIOR TO NEAR 90 IN
OUR FAR SOUTHERN COUNTIES. DEWPOINTS WERE LARGELY IN THE 60S NORTH
TO THE 70S SOUTH.
THE MAIN FOCUS FOR TONIGHT WILL DEFINITELY BE THUNDERSTORMS. THE
ATMOSPHERE HAS BEEN WORKED OVER PRETTY WELL FROM THE MCS THAT
MOVED ACROSS MUCH OF THE CWA DURING THE DAY. IT MAY STILL TAKE
SOME TIME BEFORE THINGS DESTABILIZE FURTHER FOR MORE DEVELOPMENT
LATER THIS AFTERNOON AND INTO THE EVENING. THE NMM WRF/NSSL WRF/
HRRR AND RAP NOT DOING THE BEST AS OF 330 PM. THE 4 KM NMM WRF
SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT SCENARIO. THIS MODEL
INDICATES THAT STORMS WILL FIRE UP AGAIN ACROSS NW MN AND SWEEP
FROM NW TO SE ACROSS ESPECIALLY THE SW 1/3 OF THE CWA. THIS WOULD
MAKE THE MOST SENSE AS THIS SHOULD BE THE AREA MOST APT TO
DESTABILIZE AND WITH THE BEST SURFACE CONVERGENCE. MANY OF THE
MODELS ARE ACTUALLY INDICATING THE MOST WIDESPREAD PRECIPITATION
ACROSS NORTHERN PORTIONS OF THE AREA...WHICH WOULD BE WHERE IT HAS
LARGELY STABILIZED THOUGH.
FRIDAY SHOULD BE MUCH MORE QUIET...AS A COLD FRONT BRINGS A BIT
COOLER AND DRIER AIR TO THE REGION. HIGH TEMPERATURES SHOULD STILL
BE IN THE 80S FOR THE MOST PART.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
DRY CONDITIONS ARE EXPECTED FRI NIGHT AND EARLY SAT ACROSS MUCH OF
THE UPPER MIDWEST AS A WEAK RIDGE OF HIGH PRESSURE ALOFT AND A SFC
HIGH DOMINATE THE REGION. THE NEXT SYSTEM WILL DEVELOP OVER THE NRN
PLAINS AND CANADIAN FRONT RANGE FRI NIGHT AND MOVE EWD THROUGH NRN
MN AND INTO WRN ONTARIO DURING THE DAY SAT AND SAT NIGHT. THE MODELS
ARE IN VERY GOOD AGREEMENT BRINGING THE SFC LOW EWD JUST NORTH OF
THE INTERNATIONAL BORDER INTO WRN ONTARIO BY SUNDAY MORNING...WITH A
SFC TROUGH/COLD FRONT EXTENDING SWD THROUGH MN. SHOWERS AND STORMS
ARE EXPECTED TO SPREAD ACROSS THE REGION ALONG AND AHEAD OF THIS
FRONT...WITH A CHANCE OF A FEW STRONG OR SEVERE STORMS. AS THE SFC
LOW TRACKS TO THE EAST INTO CENTRAL ONTARIO AND THE FRONT SLIDES
INTO WI/MICH U.P. A TIGHT PRES GRADIENT WILL SET UP ON THE BACK SIDE
OF THE LOW IN NE MN AND ALLOW GUSTY N WINDS TO DEVELOP WITH A FEW
SUNDAY MORNING AND AFTERNOON CAA RAIN SHOWERS. HIGH PRESSURE WILL
MOVE IN AND DOMINATE THE AREA BY MONDAY AND CONTINUE TO BRING DRY
CONDITIONS TO THE NORTHLAND THROUGH TUE AND INTO EARLY WED. A WEAK
FRONT WILL DROP SWD INTO THE REGION LATE WED AND BRING WITH IT
ADDITIONAL CHANCES FOR SHOWERS.
TEMPERATURES SATURDAY WILL CONTINUE TO BE WARM WITH HIGHS IN THE
UPPER 70S AND LOWER TO MID 80S...ALONG WITH HUMID CONDITIONS.
HOWEVER...THE COLD FRONT ON SATURDAY NIGHT WILL USHER IN A MUCH
DRIER AND COOLER AIR MASS WITH HIGHS ON SUN AND MON IN THE 60S AND
70S...AND NOTICEABLY LOWER HUMIDITIES. TEMPS WARM BA
&&
.POINT TEMPS/POPS...
DLH 80 58 79 61 / 30 0 20 50
INL 84 62 82 57 / 10 20 50 50
BRD 86 62 86 60 / 10 0 40 50
HYR 83 58 84 63 / 30 0 10 60
ASX 78 59 78 63 / 30 0 10 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
AVIATION...LE/MELDE
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1148 PM CDT Thu Aug 29 2013
.UPDATE:
Issued at 930 PM CDT Thu Aug 29 2013
Mid-evening update mainly to remove isolated thunderstorms from
the forecast over south central Illinois. The rest of the forecast
looks to be in good shape for the rest of the night. Noticed that
the RUC is spitting out some precip over parts of west central and
central Missouri late tonight in proximity to the upper low now
moving through eastern Kansas in an area of weak 850mb warm
advection. The new 00Z NAM is dry until after sunrise and then the
precip is further to the southwest. Will keep the forecast dry for
the rest of the night and let the midnight shift add in some
isolated showers or storms if something does indeed pop up.
Carney
&&
.SHORT TERM: (Through Late Tonight)
Issued at 254 PM CDT Thu Aug 29 2013
The front at midday was located from extreme southeast IA to east of
a KUIN-KSLO line into western KY, while a weak north-south surface
ridge axis was located through central MO. The front appears to be
trying to jump west into a new wind shift line closer to the MS
River. However, the more agitated cu field and axis of greatest
instability and weak CIN resides along the more eastern location,
and present indications are this would be the most favored location
for isolated shower/thunderstorm development through early evening.
After sunset the threat of any precipitation appears quite low as
the air mass will become more stable, diurnal cu will dissipate, and
any forcing along the boundary will be quite weak. Otherwise,
tonight looks rather uneventful with the upper low dropping
southeastward through KS spreading some high clouds into the western
half of the CWA, and min temperatures a tad bit warmer.
Glass
.LONG TERM: (Friday through Next Thursday)
Issued at 254 PM CDT Thu Aug 29 2013
Upper level shortwave over southwestern Missouri will continue to
slowly slide to the south on Friday. Could see a slight chance of
showers and thunderstorms mainly over the Ozarks on Friday. In the
meantime the next frontal boundary, currently over South
Dakota/western Nebraska, will move into northern Missouri by Friday
afternoon. Activity associated with this boundary, very scattered in
nature, will move into northeast MO, west central IL Friday evening.
There could be some lingering isolated activity associated with
upper level system over southern and eastern portions of forecast
area as well.
As for high temperatures on Friday, it will be a bit warmer than
today, but with a few more clouds and dewpts still mixing out, heat
indicies will remain in the 100 to 104 range, though a few spots
could reach 105.
By Saturday, cold front to weaken even more as it slides through
region. There is a chance of a few storms, mainly over far eastern
portions of forecast area. Otherwise, another hot day in store
despite a few more clouds and front moving through. Highs will be in
the low to mid 90s with heat indicies between 100 and 104.
A more vigorous cold front to approach area late Saturday night with
best chances of rain Sunday and Sunday night. Again not a lot of
moisture associated with it, so activity to be rather scattered with
it. With this front, cooler and less humid air to make its way into
region, so will keep heat advisory headline going through Saturday
for metro area, no need to extend it beyond this time period.
Beyond that, precipitation to taper off very early Monday morning
with surface ridge building in and more seasonable temperatures
expected through the work week.
Byrd
&&
.AVIATION: (For the 06z TAFs through 06z Friday Night)
Issued at 1135 PM CDT Thu Aug 29 2013
Stalled trof/boundary over extreme eastern Missouri in the process
of dissipating attm as pressure falls from retreating ridge are
allowing a gradual return of weak southerly flow across the mid-
Mississippi Valley. Due to fairly low T/Td spreads and vsby
forecasts on 00z based MET/MAV have added some MVFR vsbys in fog
at climatologically favored locations (SUS, CPS), as well as at
UIN where the visbility has already started a gradual decline.
Some of the 00z guidance is also hinting at some convection
developing over mid-Missouri by daybreak, but signal is still
fairly weak so have maintained a dry forecast for now...with a few
early morning mid clouds followed by another day of diurnal cu
development. Will also need to keep an eye on convective potential
with approaching cold front Friday night, but attm it appears that
primary threat with this feature into Friday evening will remain
north of our CWA.
Specifics for KSTL: While latest guidance and obs suggest that
there will be some vsby restriction at low lying locations (SUS
and CPS) in the STL metro believe this will not impact the STL TAF
vicinity. So...forecast for the overnight hours maintains VFR
conditions with a generally clear sky...with diurnal heating
leading to another afternoon of cu with bases aoa 5kft.
Truett
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...HEAT ADVISORY until 7 PM CDT Saturday FOR St. Charles MO-St.
Louis City MO-St. Louis MO.
IL...HEAT ADVISORY until 7 PM CDT Saturday FOR Madison IL-St. Clair
IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
225 AM PDT FRI AUG 30 2013
.SYNOPSIS...A MOIST AND UNSTABLE ATMOSPHERE WILL ALLOW FOR SHOWERS
AND THUNDERSTORMS TO DEVELOP ACROSS THE AREA THROUGH THIS WEEKEND
WITH THE GREATEST CHANCES IN THE AFTERNOON AND EVENING HOURS. THE
PRIMARY HAZARD WITH THUNDERSTORMS WILL BE HEAVY RAINFALL THAT COULD
RESULT IN FLASH FLOODING. THUNDERSTORM CHANCES ARE EXPECTED TO
DECREASE SLIGHTLY FROM MONDAY ONWARD.
&&
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT. WHAT WAS LEFT OF THE
CONVECTIVE COMPLEX THAT DEVELOPED OVER MOHAVE COUNTY YESTERDAY
AFTERNOON WAS GONE, HOWEVER, THE FOCUS EARLY THIS MORNING ON RADAR
NOW SHIFTS TO ONGOING CONVECTION ACROSS YAVAPAI AND COCONINO
COUNTIES IN ARIZONA THAT WAS MOVING WESTWARD. THE HRRR MODEL DID NOT
DO A BAD JOB INDICATING THIS. THUS USING A BLEND OF THIS MODEL AND
THE LATEST RADAR TRENDS, I WENT AHEAD AND ADJUSTED UP POPS ACROSS
MUCH OF MOHAVE COUNTY FOR EARLY THIS MORNING AS IT APPEARS MUCH OF
THIS ACTIVITY SHOULD HAVE A CHANCE AT MAKING IT OVER THE BORDER INTO
OUR AREA. THE CLOUD COVER ASSOCIATED WITH THIS AS WELL AS WHAT
REMAINS FROM THE CLOUD COVER FROM THE CONVECTIVE COMPLEX THAT FORMED
ON THURSDAY AFTERNOON WILL PRESENT A BIT OF A CHALLENGE AS THIS
COULD LIMIT HEATING LATER TODAY OVER MOHAVE COUNTY WHICH MAY DELAY
OR INHIBIT CONVECTION ALTOGETHER IN THIS AREA.
AS FAR AS WHAT GOES ON THIS AFTERNOON AND EVENING, ACTIVITY WILL BE
DRIVEN BY HEATING WITH PERHAPS SOME HELP FROM A WEAK DISTURBANCE AND
INVERTED TROUGH IN THE MID-LEVELS WORKING NORTHWEST ACROSS SOCAL.
SERIOUS MOISTURE REMAINS IN PLACE ACROSS OUR ENTIRE AREA WITH
PWATS REMAINING IN THE UPPER REACHES OF CLIMATOLOGY FOR THIS AREA,
WITH VALUES AT OR ABOVE 1.75 INCHES FORECAST TO BE AROUND FROM I-15
ON SOUTH. FORECASTED 700-300 MB THETA E VALUES ARE SHOWN TO BE AT
LEAST 340 K ACROSS MOST OF AREA AS WELL. A LOOK AT INSTABILITY
PARAMETERS OFF THE MODELS SHOWS INSTABILITY IN PLACE ACROSS OUR
ENTIRE AREA, HOWEVER, BOTH THE GFS AND ECMWF SHOW THE GREATEST LI`S
OF -2 TO -4 ACROSS MOHAVE, CLARK AND SOUTHERN NYE COUNTIES. SO WHILE
WE COULD SEE SHOWERS AND THUNDERSTORMS ACROSS ANY PORTION OF THE
AREA THIS AFTERNOON AND EVENING, ODDS LOOK TO FAVOR AN AREA WITHIN
75 MILES ON EITHER SIDE OF A LINE FROM NEAR LONE PINE TO LAS VEGAS
TO KINGMAN AS THE MOST ACTIVE LOCATIONS. THUS I WENT AHEAD AND
ISSUED A FLASH FLOOD WATCH FOR MOST OF MOHAVE, ALL OF CLARK,
SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND ALL OF INYO COUNTY EXCEPT
THE WHITE MOUNTAINS FROM LATE THIS MORNING THROUGH THIS EVENING AS
WITH SO MUCH MOISTURE IN PLACE THE UNLOAD POTENTIAL WILL BE THERE IN
ANY STRONGER OR SLOWER MOVING STORMS. THE STEERING FLOW SHOWN BY THE
WRF AND GFS IS GENERALLY LIGHT AND FROM THE EAST TODAY, HOWEVER, BY
THIS EVENING IT DOES TAKE ON MORE OF A NORTHEAST COMPONENT. THUS,
THIS MAY BE ONE OF THOSE DAYS WHERE STORMS DO NOT AFFECT THE LAS
VEGAS VALLEY UNTIL LATER THIS EVENING AS WE MAY HAVE TO WAIT FOR
ACTIVITY TO HEAD IN FROM NORTHWEST ARIZONA, NORTHEAST CLARK COUNTY
OR SOUTHWEST UTAH. ACTIVITY SHOULD DECREASE LATER THIS EVENING,
HOWEVER, CLOUDS MAY NOT COMPLETELY CLEAR OUT TONIGHT, WHICH COULD
IMPACT THE FORECAST FOR SATURDAY.
AS FAR AS SATURDAY GOES, RIDGING ALOFT WILL REMAIN CENTERED OVER THE
SOUTHWEST AND THIS WILL KEEP OUR AREA IN A SOUTHEAST FLOW ALOFT
WHICH WILL ALLOW FOR WHATEVER MOISTURE IS IN PLACE TO REMAIN WITH THE
POTENTIAL FOR ADDITIONAL MOISTURE TO WORK INTO THE AREA. ACTIVITY ON
SATURDAY WILL DEPEND ON HEATING AND THUS IF WE START OFF TOO CLOUDY
THIS COULD LIMIT WHAT WE SEE WITH RESPECT TO SHOWER AND THUNDERSTORM
ACTIVITY. THE 00Z RUNS OF THE WRF, GFS, ECMWF AS WELL AS OUR LOCAL
HI-RESOLUTION MODELS FAVORED ACTIVITY DEVELOPING MAINLY ACROSS
SOUTHERN NEVADA, INYO AND NORTHERN AND CENTRAL MOHAVE COUNTY WITH
LESS ACTIVITY FURTHER SOUTH ON THE BACK SIDE OF THE INVERTED TROUGH.
FOR NOW WE HAVE HELD OFF ON ANY FLASH FLOOD WATCHES FOR SATURDAY,
BUT WITH SO MUCH MOISTURE IN PLACE, THE MAIN CONCERN IN STORMS AGAIN
WILL BE FLASH FLOODING.
TEMPS WILL CONTINUE TO REMAIN BELOW NORMAL FOR HIGHS AND AT OR ABOVE
NORMAL FOR LOWS. I USED A BLEND OF PERSISTENCE, THE SREF AND ECMWF
FOR MAX TEMPS AND CONTINUITY AND MOS GUIDANCE FOR MIN TEMPS.
DEWPOINTS WERE ADJUSTED UP SLIGHTLY OVER GUIDANCE GIVEN HOW MOIST WE
HAVE BEEN THE PAST 2 DAYS AND IT SEEMS MODELS HAVE BEEN A LITTLE LOW
ON PICKING UP ON THIS.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...MODELS IN PRETTY GOOD
AGREEMENT SUNDAY NIGHT THROUGH TUESDAY WITH A PRETTY GENERIC MONSOON
PATTERN AND NO SIGNIFICANT WAVES IMPACTING THE AREA. HIGH PRESSURE
IS FORECAST ROUGHLY OVER THE COLORADO AND NEW MEXICO BORDER AREA
WITH AN AREA OF LOW PRESSURE OFF THE PACIFIC NORTHWEST COAST.
SOUTHERLY FLOW OVER THE FORECAST AREA WILL KEEP MONSOON MOISTURE
AROUND WITH THE DEEPEST MOISTURE OVER THE EASTERN PORTION OF THE
FORECAST AREA AS IS TYPICAL WITH THIS PATTERN. AS A RESULT WE ARE
STILL LOOKING AT A CHANCE OF THUNDERSTORMS EAST WITH A SLIGHT CHANCE
WEST. MODELS DIFFER FOR WEDNESDAY THROUGH THURSDAY WITH THE GFS AND
TO A LESSER EXTENT THE GEM MOVING THE AREA OF LOW PRESSURE INLAND.
THIS WOULD BRING DRIER AIR INTO THE AREA FROM THE WEST. THE ECMWF IS
EXPANDING THE HIGH WESTWARD WHICH MAY KEEP A BIT MORE MOISTURE IN
PLACE BUT ALSO COULD LEAD TO WARMING AND SOME STABILIZING. BASICALLY
GOING WITH A BLEND...I MADE LITTLE CHANGE TO THE INHERITED GRIDS AND
KEPT AT LEAST A SLIGHT CHANCE OVER THE EASTERN TWO THIRDS OF THE
FORECAST AREA WHILE DRYING THE WEST BY THURSDAY. ALSO WENT WITH A
WARMING TREND AND ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY.
&&
.AVIATION...FOR MCCARRAN...SHRA/TSRA ARE EXPECTED TO BE AROUND THE
VALLEY MAINLY AFTER 18Z AND ESPECIALLY AFTER 20Z TODAY. SHRA AND
TSRA ARE EXPECTED TO MOVE IN A WEST TO SOUTHWEST DIRECTION THIS
AFTERNOON AND EVENING SO ACTIVITY THAT DEVELOPS OVER NW AZ OR
NORTHEAST CLARK COUNTY WILL NEED TO BE WATCHED - ESPECIALLY FOR ANY
OUTFLOW BOUNDARIES. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS BUT
OTHERWISE COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA OR
OUTFLOW BOUNDARIES WHICH COULD IMPACT AIRPORT CONFIGURATIONS. MAINLY
SCT-BKN CLOUDS AOA 10K-15K FEET WITH LOWER CIGS AND VSBY IN AND NEAR
ANY SHRA/TSRA. ACTIVITY SHOULD DECREASE BETWEEN 03Z AND 06Z SATURDAY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...SHRA/TSRA ARE EXPECTED ACROSS THE AREA AFTER 18Z AND
ESPECIALLY AFTER 20Z TODAY WITH THE GREATEST COVERAGE ACROSS MOHAVE,
CLARK, SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND INYO COUNTIES.
SHRA AND TSRA SHOULD FAVOR A SLOW WESTWARD MOVEMENT ACROSS MOST OF
THE AREA. SHRA/TSRA COULD REDUCE VSBY AND CIGS TO MVFR OR LOWER.
WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS THROUGH THIS EVENING BUT
COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA. SCT-BKN CLOUDS
AOA 10K-15K FEET AWAY FROM ANY SHRA/TSRA.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR NVZ016>022.
AZ...FLASH FLOOD WATCH FROM 11 AM MST THIS MORNING THROUGH THIS
EVENING FOR AZZ001-003-036.
CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR CAZ519-520-522-524.
&&
$$
STACHELSKI/HARRISON
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
941 PM PDT THU AUG 29 2013
.SYNOPSIS...A FAVORABLE UPPER LEVEL FLOW PATTERN WILL CONTINUE TO
BRING MONSOON MOISTURE INTO THE AREA THROUGH THE MIDDLE OF NEXT WEEK
AND RESULT IN A CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY. THE
PRIMARY HAZARD WITH STORMS...ESPECIALLY THROUGH SUNDAY...WILL BE
HEAVY RAINFALL THAT COULD RESULT IN DANGEROUS FLASH FLOODING.
&&
.UPDATE...THE LATEST RADAR SHOWS THE CONVECTIVE COMPLEX THAT GOT
GOING OVER MOHAVE COUNTY HAS PUSHED INTO SAN BERNARDINO COUNTY BUT
DECREASED IN AREAL COVERAGE. THIS ACTIVITY WILL CONTINUE TO MOVE
WESTWARD BUT BASED ON THE HRRR AND RADAR TRENDS SHOULD START TO FALL
FURTHER APART AS IT REACHES CENTRAL SAN BERNARDINO COUNTY. THE MAIN
THREAT WILL CONTINUE TO BE HEAVY RAINFALL AND I WILL LEAVE THE FLASH
FLOOD WATCH UP UNTIL IT EXPIRES AS THIS CONVECTION IS STILL OUT
THERE. BEHIND THE LEADING EDGE OF THUNDERSTORMS...MAINLY LIGHT RAIN
WAS FALLING ACROSS MOHAVE AND FAR EASTERN SAN BERNARDINO COUNTY AND
THIS SHOULD GRADUALLY WIND DOWN OVERNIGHT. I WENT AHEAD AND REMOVED
POPS OR LOWERED THEM GREATLY ACROSS THE NORTHERN TWO-THIRDS OF THE
AREA FOR THE REST OF TONIGHT AS WE HAVE LOST HEATING AND THERE IS NO
ORGANIZED FEATURE CLOSE ENOUGH TO INITIATE CONVECTION IN THESE AREAS.
VERY STICKY AIR IS IN PLACE ACROSS OUR AREA WITH DEW POINTS WELL
INTO THE 60S AND EVEN 70S ACROSS THE MOJAVE DESERT. JUST OUTSIDE OF
OUR AREA THE DEW POINT AT BLYTHE, CALIFORNIA SPIKED TO 79 DEGREES
THIS EVENING WHICH IS ABOUT AS HIGH AS ONE WILL SEE OUT HERE IN THE
WEST AND EVEN VERY IMPRESSIVE FOR OUT EAST. I WENT AHEAD AND
ADJUSTED DEW POINTS UP OVERNIGHT A FEW DEGREES BASED ON CURRENT
OBSERVATIONS.
WITH RESPECT TO TOMORROW, I WILL TAKE A CLOSER LOOK AT THIS FOR THE
MORNING PACKAGE. FROM WHAT I HAVE LOOKED AT SO FAR, THE WRF SUGGESTS
LOTS OF LIGHT QPF ACROSS ALL OF MOHAVE COUNTY WHICH SEEMS WACKY BUT
MAY NOT BE TOO FAR OFF IF WE WIND UP STAYING CLOUDY THERE OVERNIGHT
AND FRIDAY MORNING. THE STEERING FLOW FROM THE WRF AND GFS IS SHOWN
TO BE LIGHT EAST WHICH WOULD FAVOR CONVECTION HEADING IN FROM WHAT
DEVELOPS OVER NW ARIZONA AND SW UTAH. THE LATEST MODELS ALSO FAVOR
ACTIVITY DEVELOPING OVER THE SPRING MOUNTAINS AND ACROSS INTO
COUNTY. AGAIN WITH SO MUCH MOISTURE AVAILABLE, FLASH FLOODING WILL
BE THE MAJOR CONCERN WITH STORMS, THE BIG QUESTION IS WHAT HAPPENS
TO ALL THE DEBRIS CLOUDS IN PLACE TONIGHT. IF THEY CAN CLEAR BY THE
LATE MORNING, WE WILL HAVE AMPLE HEATING AND SUFFICIENT INSTABILITY
FOR THUNDERSTORMS TO POP-UP ACROSS THE ENTIRE AREA. I WILL HOLD OFF
ON ANY NEW FLASH FLOOD WATCHES AT THIS TIME UNTIL I HAVE A BETTER
CHANCE TO INSPECT THE MODELS.
&&
.AVIATION...FOR MCCARRAN...DRY CONDITIONS ARE EXPECTED OVERNIGHT
WITH WINDS FAVORING TYPICAL DIURNAL TRENDS. SHRA/TSRA ARE EXPECTED
TO BE AROUND THE VALLEY MAINLY AFTER 18Z AND ESPECIALLY AFTER 20Z.
SHRA AND TSRA ARE EXPECTED TO MOVE IN A WEST TO SOUTHWEST DIRECTION
IN THE AFTERNOON SO ACTIVITY THAT DEVELOPS OVER NW AZ OR NORTHEAST
CLARK COUNTY WILL NEED TO BE WATCHED - ESPECIALLY FOR ANY OUTFLOW
BOUNDARIES. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS BUT OTHERWISE
COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA OR OUTFLOW
BOUNDARIES WHICH COULD IMPACT AIRPORT CONFIGURATIONS. MAINLY SCT-BKN
CLOUDS AOA 10K-15K FEET WITH LOWER CIGS AND VSBY IN AND NEAR ANY
SHRA/TSRA. ACTIVITY SHOULD DECREASE BETWEEN 03Z AND 06Z SATURDAY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...SHRA/TSRA SHOULD MAINLY BE ACROSS MOHAVE AND SAN
BERNARDINO COUNTIES OVERNIGHT WITH LITTLE TO NO ACTIVITY ELSEWHERE.
SCT-BKN CLOUDS AOA 10K-15K FEET SOUTH OF KDAG-KLAS-KSGU LINE WITH
FEW IF ANY CLOUDS TO THE NORTH. ON FRIDAY...SHRA/TSRA ARE EXPECTED
ACROSS THE AREA AFTER 18Z AND ESPECIALLY AFTER 20Z WITH THE GREATEST
COVERAGE ACROSS MOHAVE, CLARK AND INYO COUNTIES. SHRA AND TSRA
SHOULD FAVOR A SLOW WESTWARD MOVEMENT ACROSS MOST OF THE AREA.
SHRA/TSRA COULD REDUCE VSBY AND CIGS TO MVFR OR LOWER. WINDS SHOULD
FAVOR TYPICAL DIURNAL TRENDS THROUGH FRIDAY EVENING BUT COULD BE
GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA.
&&
.PREVIOUS UPDATE...
ISSUED AT 629 PM PDT THU AUG 29 2013
.UPDATE...MOST OF THE ACTION RIGHT NOW IS ACROSS MOHAVE COUNTY WHERE
CONVECTION IS PROPAGATING WESTWARD. A PSEUDO-LINE OF CONVECTION
PRESENTLY STRETCHED FROM NEAR DOLAN SPRINGS SOUTHWEST TOWARD ALAMO
DAM AND LOOKS TO HAVE ENOUGH MOMENTUM TO KEEP GOING TOWARD THE
COLORADO RIVER VALLEY. I WENT AHEAD AND INCREASED POPS BY 20-30
PERCENT IN THIS AREA BASED ON THE LATEST RADAR TRENDS. HEAVY RAIN
WILL BE THE PRIMARY HAZARD WITH STORMS IN THIS AREA, HOWEVER, GUSTY
WINDS WILL ALSO BE A CONCERN IN SPOTS. ELSEWHERE ACTIVITY IS IN THE
ISOLATED RANGE AND SHOULD START TO WIND DOWN AS WE LOOSE DAYTIME
HEATING. WE WILL NEED TO KEEP AN EYE ON SOUTHERN CLARK AND EASTERN
SAN BERNARDINO COUNTY LATER THIS EVENING TO SEE WHAT GOES ON ONCE
THE CONVECTION IN MOHAVE COUNTY GETS CLOSER TO THE BORDER.
&&
.PREVIOUS DISCUSSION...
ISSUED AT 237 PM PDT THU AUG 29 2013
.SHORT TERM...MAINLY ISOLATED THUNDERSTORMS SO FAR THIS AFTERNOON
HOWEVER EXPECTATIONS ARE FOR SOUTHERN MOHAVE AND EASTERN SAN
BERNARDINO COUNTIES TO FILL IN BASED ON STORM ACTIVITY JUST OUTSIDE
OF THE CWA AND LATEST SATELLITE TRENDS. REGARDING THESE ISOLATED
STORMS...IT IS VERY APPARENT THEY ARE LOW MOVING AND EFFICIENT RAIN
PRODUCERS. THE RADAR ESTIMATED RAIN RATES AND OBSERVED GAGE DATA ARE
QUITE IMPRESSIVE. ANY STORM THAT DEVELOPS HAS THE POTENTIAL TO
UNLOAD AND CREATE PROBLEMS QUICKLY SO REMAIN AWARE.
TONIGHT THROUGH SUNDAY...SCATTERED TO NUMEROUS HEAVY RAIN PRODUCING
SHOWERS AND THUNDERSTORMS ARE EXPECTED IN THE WATCH AREAS THIS
EVENING WITH MORE ISOLATED...BUT EQUALLY INTENSE...STORM COVERAGE
ELSEWHERE. STORMS EVERYWHERE ARE EXPECTED TO DIMINISH IN INTENSITY
AND COVERAGE OVERNIGHT. SIMILAR CONDITIONS ARE IN PLACE FOR SATURDAY
AND SUNDAY REGARDING AVAILABLE MOISTURE AND INSTABILITY. HOWEVER...
OVERALL COVERAGE COULD BE REDUCED IF FORECASTED THICKER CLOUD COVER
BECOMES A REALITY AND LIMITS DAYTIME HEATING. HOPEFULLY THIS WILL BE
CLEARER BY MORNING AND HELP DIMINISH THE CURRENT UNCERTAINTY FOR
ISSUING ANY ADDITIONAL FLASH FLOOD WATCHES FOR FRIDAY AND SATURDAY.
TEMPERATURES ARE GENERALLY EXPECTED TO BE BELOW NORMAL FRIDAY AND
SATURDAY BASED ON EXPECTED LACK OF SUNSHINE BUT COULD EXCEED
FORECASTED NUMBERS IF CLOUD COVER THINS.
.LONG TERM...MONDAY THROUGH THURSDAY...MINIMAL CHANGES MADE TO THE
EXTENDED SINCE OVERALL THINKING IS UNCHANGED. MONSOON MOISTURE WILL
REMAIN IN PLACE THROUGH THE PERIOD...WITH THE DEEPEST MOISTURE
FORECAST OVER MOHAVE COUNTY. THERE REMAINS SOME MODEL AGREEMENT THAT
A BIG RIDGE OVER THE CENTRAL STATES WILL GRADUALLY SHIFT WESTWARD BY
THE MIDDLE OF THE WEEK...RESULTING IN RISING HEIGHTS THAT COULD HELP
WARM TEMPERATURES ALOFT AND CAP THE AIRMASS. OTHERWISE...TYPICAL
MONSOON CONDITIONS ARE EXPECTED EACH AFTERNOON/EVENING MINUS ANY
TROPICAL INFLUENCE.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
AZ...FLASH FLOOD WATCH FROM NOON MST TODAY THROUGH THIS EVENING FOR
AZZ002-003.
CA...FLASH FLOOD WATCH FROM NOON PDT TODAY THROUGH THIS EVENING FOR
CAZ524>527.
&&
$$
UPDATE...STACHELSKI
PREVIOUS...SALMEN
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS RALEIGH NC
300 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION
THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP
ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL
CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 205 AM FRIDAY...
OBSERVATIONS AND MODEL DATA ALL SUPPORT A QUIET AND GENERALLY DRY
DAY WITH PLENTY OF SUNSHINE. THE LATEST SURFACE MAP SHOWS THE WEAK
SURFACE FRONT STRETCHING ACROSS SC AND SW NC... WITH SURFACE HIGH
PRESSURE NOSING IN FROM THE NE... WHILE NNW MID LEVEL FLOW AND DEEP
LAYER SUBSIDENCE PERSISTS OVER THE REGION. EXPECT A SMATTERING OF
SHALLOW LOW CLOUDS THROUGH DAYBREAK ACROSS CENTRAL NC... AS THE LACK
OF HIGHER-LEVEL MOISTURE/CLOUDS AND LIGHT EASTERLY FLOW HAS ALLOWED
FOR GOOD RADIATIONAL COOLING... WHILE HIGH DEW POINTS HOLD ON NEAR
THE SURFACE. THESE CLOUDS SHOULD MIX OUT AND DISSIPATE QUICKLY WITH
THE ONSET OF SURFACE HEATING. FORECAST SOUNDINGS SUGGESTS THAT THERE
WILL BE ENOUGH MOISTURE SUPPRESSED BENEATH THE WARM/STABLE LAYER
ALOFT TO SUPPORT SCATTERED FLAT DAYTIME CUMULUS... MORE NUMEROUS
OVER THE COASTAL PLAIN AS LOWER LEVEL MOISTURE REMAINS BETTER
HERE... AND WE MAY SEE SOME OF THE BETTER 850 MB MOISTURE NOTED OVER
AND JUST OFF THE NORTHEAST/MIDATLANTIC COAST WORKING SSW INTO ERN NC
DURING THE DAY. THE DRY ADIABATIC LOW LEVEL PROFILE SUPPORTS HIGHS
OF 84-89... SO LITTLE CHANGE IS NEEDED FROM THE EARLIER FORECAST.
THE SURFACE HIGH CENTER SHIFTS OFF THE VA/NC COAST LATER THIS
AFTERNOON THROUGH TONIGHT... RESULTING IN A VEERING OF LIGHT SURFACE
FLOW TO BE FROM THE SSE AND SOUTH... WHILE ALOFT... ANTICYCLONIC MID
LEVEL FLOW BECOMES LIGHTER AND FLATTENS OUT WITH NO FORCING
MECHANISMS EVIDENT. BUT WE SHOULD STILL SEE AN INCREASE IN HIGH THIN
CLOUDS AS BLOWOFF FROM ORGANIZED CONVECTION TODAY OVER THE NRN GREAT
LAKES ADVECTS INTO THE MIDATLANTIC REGION OVERNIGHT. LOW LEVEL
MOISTURE INCREASES AS WELL WITH THE LIGHT ATLANTIC AND GULF SOURCE
INFLOW... AND EXPECT PATCHY FOG AND A FEW LOW STRATUS CLOUDS TO FORM
ONCE AGAIN LATE TONIGHT. LOWS 65-69. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
AS OF 245 AM FRIDAY...
IT STILL APPEARS THAT SATURDAY WILL REMAIN DRY FOR MOST OF CENTRAL
NC. A SHORTWAVE TROUGH THAT CROSSES THE NRN GREAT LAKES THIS
AFTERNOON IS EXPECTED TO DAMPEN AS IT TRACKS ESE (AND INTO THE
LIGHTER STEERING FLOW) TOWARD THE CENTRAL/SRN APPALACHIANS BY SAT
MORNING. THIS FEATURE IS LIKELY TO CONTRIBUTE TO OVERALL INCREASE IN
EXTENT AND DEPTH OF MOISTURE OVER THE MOUNTAINS... ALTHOUGH THE
DYNAMIC FORCING FOR ASCENT SHOULD REMAIN QUITE WEAK. AS THIS WAVE
TRACKS INTO THE NORTHEAST STATES STRETCHING INTO WV/VA LATE SAT INTO
SAT NIGHT... A VERY WEAK LONGWAVE TROUGH FORMS OVER THE EASTERN
CONUS... WHICH SHOULD LEAD TO INCREASED CLOUDINESS EAST OF THE
MOUNTAINS BUT LITTLE ELSE. MODELS DEPICT MINIMAL INSTABILITY OVER
MUCH OF CENTRAL/ERN NC WITH AFTERNOON MLCAPE VALUES UNDER 1000 J/KG
(GFS SHOWS VALUES AT OR ABOVE 2000 J/KG JUST TO OUR WEST OVER THE
MOUNTAINS/FOOTHILLS)... AND DEEP LAYER SHEAR WILL PEAK AT JUST 15-20
KTS AT MOST. WILL MENTION AN ISOLATED SHOWER OR STORM OVER THE WRN
CWA (FAR WRN PIEDMONT) SAT AFTERNOON INTO THE EVENING. MODELS SHOW
PW VALUES OF 1.8-2.0 INCHES STREAMING FROM THE MOUNTAINS INTO
CENTRAL NC SAT NIGHT... AND FORECAST SOUNDINGS SHOW A STEADY DEEP
MOISTENING OVERNIGHT ESPECIALLY OVER THE WRN PIEDMONT. WILL RETAIN A
LOW CHANCE OF A SHOWER IN THIS AREA OVERNIGHT... ALTHOUGH THE LACK
OF MECHANISMS TO INSTIGATE LIFT SUPPORTS MOST OF THE AREA STAYING
DRY... ESPECIALLY FROM THE TRIANGLE EAST. HIGHS 85-90. LOWS 68-72.
-GIH
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 300 AM FRIDAY...
THE PATTERN FOR THE LONG TERM PORTION OF THE FORECAST WILL CONTINUE
TO FEATURE A STRONG RIDGE ACROSS THE ROCKY MOUNTAIN STATES AND AN
AMPLIFYING EASTERN U.S./CANADA TROUGH DURING THE MID TO LATE WORK
WEEK.
SUNDAY WILL FEATURE INCREASING DEEP LEVEL MOISTURE AS PRECIPITABLE
WATER VALUES INCREASE FROM AROUND 1.25 INCHES ON SATURDAY MORNING TO
BETWEEN 1.9 AND 2.0 INCHES ON SUNDAY MORNING. THE AIR MASS WILL BE
SOMEWHAT UNSTABLE BUT WILL BE LACKING A STRONG FOCUS FOR ASCENT. A
WEAKNESS/SHEAR AXIS IN THE MID LEVELS IS EXPECTED TO BE DRIFTING
EAST ACROSS THE SOUTHERN MOUNTAINS ON SUNDAY AFTERNOON WHICH WILL
SUPPORT SLIGHTLY HIGHER POPS IN THE CHANCE RANGE IN THE WEST. HIGHS
SUNDAY WILL BE SLIGHTLY ABOVE NORMAL IN THE UPPER 80S WITH LOWS
AROUND 70.
THE MAIN WEATHER EVENT OF THE LONGER TERM PERIOD ARRIVES MONDAY AND
PERSISTS INTO TUESDAY AS A DIGGING SHORT WAVE TROUGH DIVES INTO THE
OHIO VALLEY ON MONDAY. THE SHORTWAVE ASSOCIATED WITH A 70KT JET
ALOFT LINGERS ACROSS THE MID ATLANTIC MONDAY NIGHT AND TUESDAY
BEFORE ANOTHER DISTURBANCE GIVES THE TROUGH AXIS A PUSH AND MOVES IT
EAST OF CENTRAL NC ON TUESDAY. A LEE TOUGH DEVELOPS OVER CENTRAL NC
ON MONDAY WHILE THE COLD FRONT MOVES INTO THE REGION ON TUESDAY
AFTERNOON AND FINALLY PUSHES TOWARD THE COAST BY AROUND WEDNESDAY
MORNING. THE AIR MASS ACROSS CENTRAL NC WILL BE VERY MOIST WITH PW
VALUES AROUND 2.0 AND CAPE VALUES WILL CLIMB INTO THE 1500-2500 J/KG
RANGE ON MONDAY AFTERNOON ACROSS CENTRAL NC WITH THE INSTABILITY
SHIFTING EAST ON TUESDAY AFTERNOON AS A CAPPING INVERSION MOVES INTO
THE PIEDMONT. WHILE INSTABILITY IS PRESENT AND MECHANISMS
TO INITIATE AND FOCUS CONVECTION ARE IN PLACE...THE WIND FIELD IS
RATHER LIMITED WITH BULK SHEAR VALUES PROGGED TO BE AROUND OR A
LITTLE LESS THAN 20KS. SO AT THIS POINT EXPECT A PRETTY GOOD
COVERAGE OF CONVECTION...MAINLY DURING THE AFTERNOON AND EVENING.
SOME OF THE CONVECTION COULD BE STRONG BUT A WIDESPREAD SEVERE
WEATHER EVENT ISN`T EXPECTED. WILL INCLUDE HIGH CHANCE POPS DURING
THE AFTERNOON AND EVENING PERIODS WITH LINGERING LOW CHANCE POPS
OVERNIGHT. THE FOCUS FOR PRECIPITATION...ESPECIALLY THUNDERSTORMS
SHIFTS TO THE EAST ON TUESDAY AND HAVE ADJUSTED POPS UPWARD IN THOSE
LOCATIONS. HIGHS ON MONDAY WILL RANGE IN THE UPPER 80S AND A JUST A
BIT COOLER IN THE MID 80S ON TUESDAY WITH LOWS NEAR 70.
THE COLD FRONT IS PROGGED TO REACH THE COAST BY WEDNESDAY MORNING
WITH WEAK HIGH PRESSURE OVER THE WESTERN OHIO VALLEY ON WEDNESDAY
MORNING SLOWLY BUILDING EAST ON THURSDAY. THIS SHOULD RESULT IN FAIR
AND DRY WEATHER WITH COOLER TEMPERATURES. HIGHS WEDNESDAY SHOULD BE
IN THE 80-85 RANGE WITH SLIGHTLY WARMER TEMPERATURES ON THURSDAY IN
THE LOWER TO MID 80S. MORNING LOWS WILL RANGE IN THE LOWER TO MID
60S. -BLAES
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 1245 AM FRIDAY...
CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE
APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING.
SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER
THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL
REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING.
MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS
AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE
FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY
STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS
IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z...
REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT
SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR
TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP
TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z.
HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE
END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH
PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY
WEATHER TODAY.
LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF
IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING
(09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER
MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE
EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR
CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT
AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS
SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY
AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND
STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...BLAES
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
245 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION
THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP
ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL
CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 205 AM FRIDAY...
OBSERVATIONS AND MODEL DATA ALL SUPPORT A QUIET AND GENERALLY DRY
DAY WITH PLENTY OF SUNSHINE. THE LATEST SURFACE MAP SHOWS THE WEAK
SURFACE FRONT STRETCHING ACROSS SC AND SW NC... WITH SURFACE HIGH
PRESSURE NOSING IN FROM THE NE... WHILE NNW MID LEVEL FLOW AND DEEP
LAYER SUBSIDENCE PERSISTS OVER THE REGION. EXPECT A SMATTERING OF
SHALLOW LOW CLOUDS THROUGH DAYBREAK ACROSS CENTRAL NC... AS THE LACK
OF HIGHER-LEVEL MOISTURE/CLOUDS AND LIGHT EASTERLY FLOW HAS ALLOWED
FOR GOOD RADIATIONAL COOLING... WHILE HIGH DEW POINTS HOLD ON NEAR
THE SURFACE. THESE CLOUDS SHOULD MIX OUT AND DISSIPATE QUICKLY WITH
THE ONSET OF SURFACE HEATING. FORECAST SOUNDINGS SUGGESTS THAT THERE
WILL BE ENOUGH MOISTURE SUPPRESSED BENEATH THE WARM/STABLE LAYER
ALOFT TO SUPPORT SCATTERED FLAT DAYTIME CUMULUS... MORE NUMEROUS
OVER THE COASTAL PLAIN AS LOWER LEVEL MOISTURE REMAINS BETTER
HERE... AND WE MAY SEE SOME OF THE BETTER 850 MB MOISTURE NOTED OVER
AND JUST OFF THE NORTHEAST/MIDATLANTIC COAST WORKING SSW INTO ERN NC
DURING THE DAY. THE DRY ADIABATIC LOW LEVEL PROFILE SUPPORTS HIGHS
OF 84-89... SO LITTLE CHANGE IS NEEDED FROM THE EARLIER FORECAST.
THE SURFACE HIGH CENTER SHIFTS OFF THE VA/NC COAST LATER THIS
AFTERNOON THROUGH TONIGHT... RESULTING IN A VEERING OF LIGHT SURFACE
FLOW TO BE FROM THE SSE AND SOUTH... WHILE ALOFT... ANTICYCLONIC MID
LEVEL FLOW BECOMES LIGHTER AND FLATTENS OUT WITH NO FORCING
MECHANISMS EVIDENT. BUT WE SHOULD STILL SEE AN INCREASE IN HIGH THIN
CLOUDS AS BLOWOFF FROM ORGANIZED CONVECTION TODAY OVER THE NRN GREAT
LAKES ADVECTS INTO THE MIDATLANTIC REGION OVERNIGHT. LOW LEVEL
MOISTURE INCREASES AS WELL WITH THE LIGHT ATLANTIC AND GULF SOURCE
INFLOW... AND EXPECT PATCHY FOG AND A FEW LOW STRATUS CLOUDS TO FORM
ONCE AGAIN LATE TONIGHT. LOWS 65-69. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
AS OF 245 AM FRIDAY...
IT STILL APPEARS THAT SATURDAY WILL REMAIN DRY FOR MOST OF CENTRAL
NC. A SHORTWAVE TROUGH THAT CROSSES THE NRN GREAT LAKES THIS
AFTERNOON IS EXPECTED TO DAMPEN AS IT TRACKS ESE (AND INTO THE
LIGHTER STEERING FLOW) TOWARD THE CENTRAL/SRN APPALACHIANS BY SAT
MORNING. THIS FEATURE IS LIKELY TO CONTRIBUTE TO OVERALL INCREASE IN
EXTENT AND DEPTH OF MOISTURE OVER THE MOUNTAINS... ALTHOUGH THE
DYNAMIC FORCING FOR ASCENT SHOULD REMAIN QUITE WEAK. AS THIS WAVE
TRACKS INTO THE NORTHEAST STATES STRETCHING INTO WV/VA LATE SAT INTO
SAT NIGHT... A VERY WEAK LONGWAVE TROUGH FORMS OVER THE EASTERN
CONUS... WHICH SHOULD LEAD TO INCREASED CLOUDINESS EAST OF THE
MOUNTAINS BUT LITTLE ELSE. MODELS DEPICT MINIMAL INSTABILITY OVER
MUCH OF CENTRAL/ERN NC WITH AFTERNOON MLCAPE VALUES UNDER 1000 J/KG
(GFS SHOWS VALUES AT OR ABOVE 2000 J/KG JUST TO OUR WEST OVER THE
MOUNTAINS/FOOTHILLS)... AND DEEP LAYER SHEAR WILL PEAK AT JUST 15-20
KTS AT MOST. WILL MENTION AN ISOLATED SHOWER OR STORM OVER THE WRN
CWA (FAR WRN PIEDMONT) SAT AFTERNOON INTO THE EVENING. MODELS SHOW
PW VALUES OF 1.8-2.0 INCHES STREAMING FROM THE MOUNTAINS INTO
CENTRAL NC SAT NIGHT... AND FORECAST SOUNDINGS SHOW A STEADY DEEP
MOISTENING OVERNIGHT ESPECIALLY OVER THE WRN PIEDMONT. WILL RETAIN A
LOW CHANCE OF A SHOWER IN THIS AREA OVERNIGHT... ALTHOUGH THE LACK
OF MECHANISMS TO INSTIGATE LIFT SUPPORTS MOST OF THE AREA STAYING
DRY... ESPECIALLY FROM THE TRIANGLE EAST. HIGHS 85-90. LOWS 68-72.
-GIH
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 235 PM THURSDAY...
SIGNIFICANT AMPLIFICATION IN THE LONGWAVE PATTERN OVER NOAM THROUGH
THE EXTENDED FORECAST PERIOD WILL RESULT IN A PROGRESSIVE TROF
MOVING ACROSS THE EASTERN CONUS EARLY NEXT WEEK.
SUNDAY...WILL SEE INCREASING MOISTURE AS RETURN FLOW DEVELOPS AND
STRENGTHENS OVER THE WEEKEND. INITIAL WESTERLY LOW LEVEL FLOW WILL
PROMOTE DEVELOPMENT OF LEE TROFFING SATURDAY WITH SMALL CHANCES OF
CONVECTION...MAINLY IN THE WEST WHERE SURFACE TROF INFLUENCE AND
DIFFERENTIAL HEATING ON THE SLOPES AND SUBSEQUENT MIGRATION OF CELLS
EAST WILL BE THE MAJOR INFLUENCES. WILL HAVE A BETTER CHANCE OF
CONVECTION...WITH A LATE DAY/DIURNAL INFLUENCE...ON SUNDAY AS BOTH
THE GFS AND ECMWF INDICATE A SHORT WAVE GRAZING THE AREA AS IT
ROUNDS THE UPPER TROF. HIGHS BOTH DAYS WILL BE MAINLY 85-90.
MONDAY AND TUESDAY...PW`S WILL BE ON THE ORDER OF 2 INCHES AND THE
EAST COAST TROF AXIS WILL BE JUST WEST OF THE AREA ON MONDAY WITH
A 70KT UPPER JETLET LIFTING NORTH UP THE EASTERN RIM OF THE TROF TO
ADD SOME UPPER DIFFLUENCE TO ENHANCE CONVECTION. SEEING SOME
CONVECTIVE FEEDBACK PROBLEMS IN THE GFS VORTICITY FIELDS WHICH
DIMINISHES CONFIDENCE ENOUGH TO PREVENT ME FROM INCREASING POPS TO
LIKELY AT THIS POINT. HIGHS MONDAY WILL BE SIMILAR TO THE WEEKEND
WITH NO AIRMASS CHANGE...85 TO 90...PERHAPS A SHADE LOWER IF CLOUD
AND SHOWER COVERAGE ARE MORE SIGNIFICANT EARLY IN THE DAY. A COLD
FRONT APPROACHING FROM THE NORTHWEST WILL BE MERGING INTO THE
PERSISTENT LEE TROF MONDAY NIGHT AND PROGRESSING SLOWLY EAST ACROSS
THE AREA TUESDAY. WILL HAVE CHANCE POPS FOR MAINLY SHOWERS OVERNIGHT
AND TUESDAY MORNING...WITH BETTER CHANCES OF THUNDER ON TUESDAY
AFTERNOON/EVENING...ESPECIALLY IN THE EAST. COOL AIR ADVECTION WILL
BE DELAYED UNTIL TUESDAY NIGHT...AND HIGHS TUESDAY WILL BE MAINLY
TEMPERED A BIT BY HEAVY CLOUD AND MORE WIDESPREAD SHOWER COVERAGE...
84 NORTHWEST TO 88 SOUTHEAST.
WEDNESDAY AND THURSDAY...SURFACE FRONT WILL BE ALONG THE COAST
TUESDAY NIGHT...WITH HIGH PRESSURE BUILDING IN FROM THE MIDWEST ON
WEDNESDAY. WILL HAVE CLEARING SKIES AND A COOLER AIRMASS IN
PLACE...HIGHS WEDNESDAY WILL BE IN THE 80-85 RANGE AFTER A MORNING
LOW IN THE LOW-MID 60S. MAINLY CLEAR WITH INSOLATION WARMING US A
BIT ON THURSDAY...MOSTLY MID 80S.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 1245 AM FRIDAY...
CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE
APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING.
SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER
THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL
REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING.
MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS
AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE
FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY
STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS
IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z...
REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT
SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR
TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP
TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z.
HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE
END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH
PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY
WEATHER TODAY.
LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF
IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING
(09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER
MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE
EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR
CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT
AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS
SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY
AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND
STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...MLM
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
205 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION
THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP
ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL
CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 205 AM FRIDAY...
OBSERVATIONS AND MODEL DATA ALL SUPPORT A QUIET AND GENERALLY DRY
DAY WITH PLENTY OF SUNSHINE. THE LATEST SURFACE MAP SHOWS THE WEAK
SURFACE FRONT STRETCHING ACROSS SC AND SW NC... WITH SURFACE HIGH
PRESSURE NOSING IN FROM THE NE... WHILE NNW MID LEVEL FLOW AND DEEP
LAYER SUBSIDENCE PERSISTS OVER THE REGION. EXPECT A SMATTERING OF
SHALLOW LOW CLOUDS THROUGH DAYBREAK ACROSS CENTRAL NC... AS THE LACK
OF HIGHER-LEVEL MOISTURE/CLOUDS AND LIGHT EASTERLY FLOW HAS ALLOWED
FOR GOOD RADIATIONAL COOLING... WHILE HIGH DEW POINTS HOLD ON NEAR
THE SURFACE. THESE CLOUDS SHOULD MIX OUT AND DISSIPATE QUICKLY WITH
THE ONSET OF SURFACE HEATING. FORECAST SOUNDINGS SUGGESTS THAT THERE
WILL BE ENOUGH MOISTURE SUPPRESSED BENEATH THE WARM/STABLE LAYER
ALOFT TO SUPPORT SCATTERED FLAT DAYTIME CUMULUS... MORE NUMEROUS
OVER THE COASTAL PLAIN AS LOWER LEVEL MOISTURE REMAINS BETTER
HERE... AND WE MAY SEE SOME OF THE BETTER 850 MB MOISTURE NOTED OVER
AND JUST OFF THE NORTHEAST/MIDATLANTIC COAST WORKING SSW INTO ERN NC
DURING THE DAY. THE DRY ADIABATIC LOW LEVEL PROFILE SUPPORTS HIGHS
OF 84-89... SO LITTLE CHANGE IS NEEDED FROM THE EARLIER FORECAST.
THE SURFACE HIGH CENTER SHIFTS OFF THE VA/NC COAST LATER THIS
AFTERNOON THROUGH TONIGHT... RESULTING IN A VEERING OF LIGHT SURFACE
FLOW TO BE FROM THE SSE AND SOUTH... WHILE ALOFT... ANTICYCLONIC MID
LEVEL FLOW BECOMES LIGHTER AND FLATTENS OUT WITH NO FORCING
MECHANISMS EVIDENT. BUT WE SHOULD STILL SEE AN INCREASE IN HIGH THIN
CLOUDS AS BLOWOFF FROM ORGANIZED CONVECTION TODAY OVER THE NRN GREAT
LAKES ADVECTS INTO THE MIDATLANTIC REGION OVERNIGHT. LOW LEVEL
MOISTURE INCREASES AS WELL WITH THE LIGHT ATLANTIC AND GULF SOURCE
INFLOW... AND EXPECT PATCHY FOG AND A FEW LOW STRATUS CLOUDS TO FORM
ONCE AGAIN LATE TONIGHT. LOWS 65-69. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
AS OF 230 PM THURSDAY...
TO BE UPDATED SHORTLY.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 235 PM THURSDAY...
SIGNIFICANT AMPLIFICATION IN THE LONGWAVE PATTERN OVER NOAM THROUGH
THE EXTENDED FORECAST PERIOD WILL RESULT IN A PROGRESSIVE TROF
MOVING ACROSS THE EASTERN CONUS EARLY NEXT WEEK.
SUNDAY...WILL SEE INCREASING MOISTURE AS RETURN FLOW DEVELOPS AND
STRENGTHENS OVER THE WEEKEND. INITIAL WESTERLY LOW LEVEL FLOW WILL
PROMOTE DEVELOPMENT OF LEE TROFFING SATURDAY WITH SMALL CHANCES OF
CONVECTION...MAINLY IN THE WEST WHERE SURFACE TROF INFLUENCE AND
DIFFERENTIAL HEATING ON THE SLOPES AND SUBSEQUENT MIGRATION OF CELLS
EAST WILL BE THE MAJOR INFLUENCES. WILL HAVE A BETTER CHANCE OF
CONVECTION...WITH A LATE DAY/DIURNAL INFLUENCE...ON SUNDAY AS BOTH
THE GFS AND ECMWF INDICATE A SHORT WAVE GRAZING THE AREA AS IT
ROUNDS THE UPPER TROF. HIGHS BOTH DAYS WILL BE MAINLY 85-90.
MONDAY AND TUESDAY...PW`S WILL BE ON THE ORDER OF 2 INCHES AND THE
EAST COAST TROF AXIS WILL BE JUST WEST OF THE AREA ON MONDAY WITH
A 70KT UPPER JETLET LIFTING NORTH UP THE EASTERN RIM OF THE TROF TO
ADD SOME UPPER DIFFLUENCE TO ENHANCE CONVECTION. SEEING SOME
CONVECTIVE FEEDBACK PROBLEMS IN THE GFS VORTICITY FIELDS WHICH
DIMINISHES CONFIDENCE ENOUGH TO PREVENT ME FROM INCREASING POPS TO
LIKELY AT THIS POINT. HIGHS MONDAY WILL BE SIMILAR TO THE WEEKEND
WITH NO AIRMASS CHANGE...85 TO 90...PERHAPS A SHADE LOWER IF CLOUD
AND SHOWER COVERAGE ARE MORE SIGNIFICANT EARLY IN THE DAY. A COLD
FRONT APPROACHING FROM THE NORTHWEST WILL BE MERGING INTO THE
PERSISTENT LEE TROF MONDAY NIGHT AND PROGRESSING SLOWLY EAST ACROSS
THE AREA TUESDAY. WILL HAVE CHANCE POPS FOR MAINLY SHOWERS OVERNIGHT
AND TUESDAY MORNING...WITH BETTER CHANCES OF THUNDER ON TUESDAY
AFTERNOON/EVENING...ESPECIALLY IN THE EAST. COOL AIR ADVECTION WILL
BE DELAYED UNTIL TUESDAY NIGHT...AND HIGHS TUESDAY WILL BE MAINLY
TEMPERED A BIT BY HEAVY CLOUD AND MORE WIDESPREAD SHOWER COVERAGE...
84 NORTHWEST TO 88 SOUTHEAST.
WEDNESDAY AND THURSDAY...SURFACE FRONT WILL BE ALONG THE COAST
TUESDAY NIGHT...WITH HIGH PRESSURE BUILDING IN FROM THE MIDWEST ON
WEDNESDAY. WILL HAVE CLEARING SKIES AND A COOLER AIRMASS IN
PLACE...HIGHS WEDNESDAY WILL BE IN THE 80-85 RANGE AFTER A MORNING
LOW IN THE LOW-MID 60S. MAINLY CLEAR WITH INSOLATION WARMING US A
BIT ON THURSDAY...MOSTLY MID 80S.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 1245 AM FRIDAY...
CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE
APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING.
SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER
THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL
REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING.
MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS
AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE
FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY
STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS
IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z...
REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT
SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR
TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP
TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z.
HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE
END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH
PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY
WEATHER TODAY.
LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF
IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING
(09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER
MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE
EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR
CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT
AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS
SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY
AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND
STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...HARTFIELD
SHORT TERM...
LONG TERM...MLM
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1250 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION
THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP
ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL
CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY.
&&
.NEAR TERM /OVERNIGHT/...
AS OF 815 PM THURSDAY...
OVERVIEW:
NW FLOW ALOFT WILL PREVAIL OVER THE MID-ATLANTIC AND CAROLINAS
OVERNIGHT...BETWEEN AN EXPANSIVE H5 RIDGE OVER THE CENTRAL PLAINS/
ROCKIES AND AN H5 TROUGH OFFSHORE THE EASTERN SEABOARD. SFC HIGH
PRESSURE WILL STRENGTHEN OVER THE MID-ATLANTIC...WITH INCREASINGLY
NORTHEAST LOW-LEVEL FLOW OVER CENTRAL NC.
PRECIPITATION CHANCES:
ASIDE FROM A CHANCE FOR ISOLD LOW-TOPPED CONVECTION WEST OF A LINE
FROM FAY-RDU-HNZ THROUGH MIDNIGHT...EXPECT NO ADDITIONAL POTENTIAL
FOR PRECIPITATION AS A DRIER AIRMASS ADVECTS INTO THE REGION FROM
THE EAST/ENE AND SUBSIDENCE STRENGTHENS IN ASSOC/W INCREASINGLY
DIFFLUENT FLOW ALOFT.
TEMPERATURES:
LOWS WILL PRIMARILY DEPEND ON CLOUD COVER AND THE ADVECTION OF A
COOLER MARITIME AIRMASS INTO THE REGION VIA NORTHEAST FLOW IN THE
LOWER LEVELS. EXPECT LOWS RANGING FROM THE MID/UPPER 60S N/NE TO
NEAR 70F FAR S/SW. -VINCENT
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 230 PM THURSDAY...
QUIET WEATHER-WISE.
WEAK SURFACE HIGH PRESSURE WILL BUILD INTO THE AREA FRIDAY
MORNING...WHILE CONTINUED NWLY FLOW ALOFT LOOKS TO BE VOID OF ANY
SHORTWAVE DISTURBANCES. BELOW NORMAL PWATS OF AROUND 1.0" WITH
CAPPING ALOFT WILL RESULT IN DRY CONDITIONS WITH AMPLE SUNSHINE
SUPPORTING SEASONABLE TEMPERATURES IN THE MID TO UPPER 80S.
SURFACE HIGH WILL THEN SHIFT OFFSHORE FRIDAY EVENING WITH
SURFACE WINDS VEERING TO EAST-SOUTHEASTERLY FRIDAY NIGHT.
SIGNALS ARE MIXED ON WHETHER WE WILL SEE FOG...STRATUS...OR
A MIX OF BOTH. LOWS IN THE MID 60S TO LOWER 70S.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
AS OF 235 PM THURSDAY...
SIGNIFICANT AMPLIFICATION IN THE LONGWAVE PATTERN OVER NOAM THROUGH
THE EXTENDED FORECAST PERIOD WILL RESULT IN A PROGRESSIVE TROF
MOVING ACROSS THE EASTERN CONUS EARLY NEXT WEEK.
SATURDAY AND SUNDAY...WILL SEE INCREASING MOISTURE AS RETURN FLOW
DEVELOPS AND STRENGTHENS OVER THE WEEKEND. INITIAL WESTERLY LOW
LEVEL FLOW WILL PROMOTE DEVELOPMENT OF LEE TROFFING SATURDAY WITH
SMALL CHANCES OF CONVECTION...MAINLY IN THE WEST WHERE SURFACE TROF
INFLUENCE AND DIFFERENTIAL HEATING ON THE SLOPES AND SUBSEQUENT
MIGRATION OF CELLS EAST WILL BE THE MAJOR INFLUENCES. WILL HAVE A
BETTER CHANCE OF CONVECTION...WITH A LATE DAY/DIURNAL INFLUENCE...ON
SUNDAY AS BOTH THE GFS AND ECMWF INDICATE A SHORT WAVE GRAZING THE
AREA AS IT ROUNDS THE UPPER TROF. HIGHS BOTH DAYS WILL BE MAINLY
85-90.
MONDAY AND TUESDAY...PW`S WILL BE ON THE ORDER OF 2 INCHES AND THE
EAST COAST TROF AXIS WILL BE JUST WEST OF THE AREA ON MONDAY WITH
A 70KT UPPER JETLET LIFTING NORTH UP THE EASTERN RIM OF THE TROF TO
ADD SOME UPPER DIFFLUENCE TO ENHANCE CONVECTION. SEEING SOME
CONVECTIVE FEEDBACK PROBLEMS IN THE GFS VORTICITY FIELDS WHICH
DIMINISHES CONFIDENCE ENOUGH TO PREVENT ME FROM INCREASING POPS TO
LIKELY AT THIS POINT. HIGHS MONDAY WILL BE SIMILAR TO THE WEEKEND
WITH NO AIRMASS CHANGE...85 TO 90...PERHAPS A SHADE LOWER IF CLOUD
AND SHOWER COVERAGE ARE MORE SIGNIFICANT EARLY IN THE DAY. A COLD
FRONT APPROACHING FROM THE NORTHWEST WILL BE MERGING INTO THE
PERSISTENT LEE TROF MONDAY NIGHT AND PROGRESSING SLOWLY EAST ACROSS
THE AREA TUESDAY. WILL HAVE CHANCE POPS FOR MAINLY SHOWERS OVERNIGHT
AND TUESDAY MORNING...WITH BETTER CHANCES OF THUNDER ON TUESDAY
AFTERNOON/EVENING...ESPECIALLY IN THE EAST. COOL AIR ADVECTION WILL
BE DELAYED UNTIL TUESDAY NIGHT...AND HIGHS TUESDAY WILL BE MAINLY
TEMPERED A BIT BY HEAVY CLOUD AND MORE WIDESPREAD SHOWER COVERAGE...
84 NORTHWEST TO 88 SOUTHEAST.
WEDNESDAY AND THURSDAY...SURFACE FRONT WILL BE ALONG THE COAST
TUESDAY NIGHT...WITH HIGH PRESSURE BUILDING IN FROM THE MIDWEST ON
WEDNESDAY. WILL HAVE CLEARING SKIES AND A COOLER AIRMASS IN
PLACE...HIGHS WEDNESDAY WILL BE IN THE 80-85 RANGE AFTER A MORNING
LOW IN THE LOW-MID 60S. MAINLY CLEAR WITH INSOLATION WARMING US A
BIT ON THURSDAY...MOSTLY MID 80S.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 1245 AM FRIDAY...
CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE
APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING.
SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER
THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL
REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING.
MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS
AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE
FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY
STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS
IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z...
REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT
SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR
TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP
TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z.
HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE
END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH
PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY
WEATHER TODAY.
LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF
IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING
(09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER
MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE
EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR
CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT
AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS
SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY
AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND
STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...VINCENT
SHORT TERM...CBL
LONG TERM...MLM
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1245 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION
THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP
ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL
CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY.
&&
.NEAR TERM /OVERNIGHT/...
AS OF 815 PM THURSDAY...
OVERVIEW:
NW FLOW ALOFT WILL PREVAIL OVER THE MID-ATLANTIC AND CAROLINAS
OVERNIGHT...BETWEEN AN EXPANSIVE H5 RIDGE OVER THE CENTRAL PLAINS/
ROCKIES AND AN H5 TROUGH OFFSHORE THE EASTERN SEABOARD. SFC HIGH
PRESSURE WILL STRENGTHEN OVER THE MID-ATLANTIC...WITH INCREASINGLY
NORTHEAST LOW-LEVEL FLOW OVER CENTRAL NC.
PRECIPITATION CHANCES:
ASIDE FROM A CHANCE FOR ISOLD LOW-TOPPED CONVECTION WEST OF A LINE
FROM FAY-RDU-HNZ THROUGH MIDNIGHT...EXPECT NO ADDITIONAL POTENTIAL
FOR PRECIPITATION AS A DRIER AIRMASS ADVECTS INTO THE REGION FROM
THE EAST/ENE AND SUBSIDENCE STRENGTHENS IN ASSOC/W INCREASINGLY
DIFFLUENT FLOW ALOFT.
TEMPERATURES:
LOWS WILL PRIMARILY DEPEND ON CLOUD COVER AND THE ADVECTION OF A
COOLER MARITIME AIRMASS INTO THE REGION VIA NORTHEAST FLOW IN THE
LOWER LEVELS. EXPECT LOWS RANGING FROM THE MID/UPPER 60S N/NE TO
NEAR 70F FAR S/SW. -VINCENT
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 230 PM THURSDAY...
QUIET WEATHER-WISE.
WEAK SURFACE HIGH PRESSURE WILL BUILD INTO THE AREA FRIDAY
MORNING...WHILE CONTINUED NWLY FLOW ALOFT LOOKS TO BE VOID OF ANY
SHORTWAVE DISTURBANCES. BELOW NORMAL PWATS OF AROUND 1.0" WITH
CAPPING ALOFT WILL RESULT IN DRY CONDITIONS WITH AMPLE SUNSHINE
SUPPORTING SEASONABLE TEMPERATURES IN THE MID TO UPPER 80S.
SURFACE HIGH WILL THEN SHIFT OFFSHORE FRIDAY EVENING WITH
SURFACE WINDS VEERING TO EAST-SOUTHEASTERLY FRIDAY NIGHT.
SIGNALS ARE MIXED ON WHETHER WE WILL SEE FOG...STRATUS...OR
A MIX OF BOTH. LOWS IN THE MID 60S TO LOWER 70S.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
AS OF 235 PM THURSDAY...
SIGNIFICANT AMPLIFICATION IN THE LONGWAVE PATTERN OVER NOAM THROUGH
THE EXTENDED FORECAST PERIOD WILL RESULT IN A PROGRESSIVE TROF
MOVING ACROSS THE EASTERN CONUS EARLY NEXT WEEK.
SATURDAY AND SUNDAY...WILL SEE INCREASING MOISTURE AS RETURN FLOW
DEVELOPS AND STRENGTHENS OVER THE WEEKEND. INITIAL WESTERLY LOW
LEVEL FLOW WILL PROMOTE DEVELOPMENT OF LEE TROFFING SATURDAY WITH
SMALL CHANCES OF CONVECTION...MAINLY IN THE WEST WHERE SURFACE TROF
INFLUENCE AND DIFFERENTIAL HEATING ON THE SLOPES AND SUBSEQUENT
MIGRATION OF CELLS EAST WILL BE THE MAJOR INFLUENCES. WILL HAVE A
BETTER CHANCE OF CONVECTION...WITH A LATE DAY/DIURNAL INFLUENCE...ON
SUNDAY AS BOTH THE GFS AND ECMWF INDICATE A SHORT WAVE GRAZING THE
AREA AS IT ROUNDS THE UPPER TROF. HIGHS BOTH DAYS WILL BE MAINLY
85-90.
MONDAY AND TUESDAY...PW`S WILL BE ON THE ORDER OF 2 INCHES AND THE
EAST COAST TROF AXIS WILL BE JUST WEST OF THE AREA ON MONDAY WITH
A 70KT UPPER JETLET LIFTING NORTH UP THE EASTERN RIM OF THE TROF TO
ADD SOME UPPER DIFFLUENCE TO ENHANCE CONVECTION. SEEING SOME
CONVECTIVE FEEDBACK PROBLEMS IN THE GFS VORTICITY FIELDS WHICH
DIMINISHES CONFIDENCE ENOUGH TO PREVENT ME FROM INCREASING POPS TO
LIKELY AT THIS POINT. HIGHS MONDAY WILL BE SIMILAR TO THE WEEKEND
WITH NO AIRMASS CHANGE...85 TO 90...PERHAPS A SHADE LOWER IF CLOUD
AND SHOWER COVERAGE ARE MORE SIGNIFICANT EARLY IN THE DAY. A COLD
FRONT APPROACHING FROM THE NORTHWEST WILL BE MERGING INTO THE
PERSISTENT LEE TROF MONDAY NIGHT AND PROGRESSING SLOWLY EAST ACROSS
THE AREA TUESDAY. WILL HAVE CHANCE POPS FOR MAINLY SHOWERS OVERNIGHT
AND TUESDAY MORNING...WITH BETTER CHANCES OF THUNDER ON TUESDAY
AFTERNOON/EVENING...ESPECIALLY IN THE EAST. COOL AIR ADVECTION WILL
BE DELAYED UNTIL TUESDAY NIGHT...AND HIGHS TUESDAY WILL BE MAINLY
TEMPERED A BIT BY HEAVY CLOUD AND MORE WIDESPREAD SHOWER COVERAGE...
84 NORTHWEST TO 88 SOUTHEAST.
WEDNESDAY AND THURSDAY...SURFACE FRONT WILL BE ALONG THE COAST
TUESDAY NIGHT...WITH HIGH PRESSURE BUILDING IN FROM THE MIDWEST ON
WEDNESDAY. WILL HAVE CLEARING SKIES AND A COOLER AIRMASS IN
PLACE...HIGHS WEDNESDAY WILL BE IN THE 80-85 RANGE AFTER A MORNING
LOW IN THE LOW-MID 60S. MAINLY CLEAR WITH INSOLATION WARMING US A
BIT ON THURSDAY...MOSTLY MID 80S.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 1245 AM FRIDAY...
CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE
APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING.
SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER
THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL
REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING.
MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS
AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE
FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY
STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS
IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z...
REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT
SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR
TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP
TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z.
HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE
END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH
PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY
WEATHER TODAY.
LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF
IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING
(09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER
MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE
EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR
CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT
AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS
SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY
AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND
STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...VINCENT
SHORT TERM...CBL
LONG TERM...MLM
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
500 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST
EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND
WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE
NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE
RETURNS ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
415 AM UPDATE...PRECIP COVERAGE HAS INCREASED OVER THE PAST HOUR AS
SUGGESTED BY EARLIER HRRR RUNS...HOWEVER NOT QUITE AS EXPECTED.
EASTERLY FLOW DOES CONTINUE TO PLAY A PART IN DRIVING LIGHT SHOWER
ACTIVITY IN THE FOOTHILLS...BUT STRONGER CELLS NOW FAVOR THE WRN
PORTION OF THE UPSTATE WHERE SPC MESOANALYSIS INDICATES GREATEST SFC
INSTABILITY IS PRESENT LIKELY DUE TO HIGHER DEWPOINTS. MAINTAINED
POP MENTION ALL ALONG THE BLUE RIDGE BUT NOW FEATURE BEST CHANCES IN
THE UPSTATE. RAIN RATES ARE RATHER HIGH AND REFLECTIVE OF ABUNDANT
MOISTURE...BUT CELL MOTION SO FAR HAS BEEN ENOUGH TO PRECLUDE FLASH
FLOOD THREAT. LLVL FLOW SHOWN TO WEAKEN SLIGHTLY TOWARD DAWN ON 06Z
NAM SO IT IS WISE TO CONTINUE TO MONITOR CLOSELY.
AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION
WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL
LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE
REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK
OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE
RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY
CORRESPONDINGLY GREATER.
UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER
THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS
THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO
MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW
CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS
CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST
CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER
THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 225 AM FRI...THE CWFA WILL REMAIN IN A WEAKNESS BETWEEN THE
RIDGING OVER THE CENTRAL CONUS AND THE ATLANTIC. THIS ALLOWS WEAK
SHORT WAVES MOVING THRU THE WESTERLIES TO DIG A SHALLOW TROF OVER
THE ERN CONUS EARLY IN THE PERIOD AND A STRONGER TROF BY MONDAY AS
AN UPPER LOW MOVES INTO THE GREAT LAKES REGION. WEAK S TO SWLY LOW
LEVEL FLOW KEEPS COPIOUS MOISTURE OVER THE AREA WITH PW VALUES AS
HIGH AS 2 INCHES. THIS COMBINED WITH MODERATE INSTABILITY WILL LEAD
TO DIURNAL CONVECTION BOTH SAT AND SUN AFTERNOONS. COVERAGE BOTH
DAYS WILL FAVOR THE MTNS WITH LOWER...BUT STILL SCT...CHC OVER THE
PIEDMONT. HIGHS WILL BE NEARLY STEADY NEAR NORMAL BOTH DAYS WITH
LOWS NEARLY STEADY ABOUT 5 DEGREES ABOVE NORMAL.
A WEAK FRONT MOVES IN WITH THE STRONGER TROF ON MON. EVEN WITH THE
FRONT AND TROF...CONVECTIVE COVERAGE WILL FAVOR THE MTNS AND TAPER
OFF TO THE PIEDMONT. HIGHS WILL BE NEAR TO SLIGHTLY ABOVE NORMAL.
WITH COPIOUS MOISTURE AND SLOW MOVING STORMS...HEAVY RAINFALL IS
POSSIBLE...POTENTIALLY LEADING TO ISOLATED FLASH FLOODING EACH DAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 310 AM FRI...AN UPPER TROF STARTS OUT OVER THE ERN CONUS ON
TUE THEN SLIDES OFF SHORE WED. THE CWFA REMAINS IN LIGHT NWLY FLOW
THRU THE END OF THE PERIOD WITH LITTLE IN THE WAY OF SHORT WAVE
ACTIVITY DROPPING THRU THE FLOW. AT THE SFC...A COLD FRONT STARTS
OUT OVER THE AREA TUE THEN SLIDES SOUTH AND EAST OF THE AREA WED AS
HIGH PRESSURE BUILDS IN FROM THE NW THU. ALL THIS LEADS TO DIURNAL
SCT CONVECTION TUE. THERE IS SOME INDICATION THAT MOISTURE COULD
LINGER OVER THE SAV RIVER VALLEY OR SWRN NC MTNS ON WED WITH DRIER
AIR MOVING IN ELSEWHERE. HOWEVER...HAVE KEPT FCST DRY FOR NOW. DRY
FCST CONTINUES THU. TEMPERATURES FALL BELOW NORMAL WITH COOLER HIGH
PRESSURE MOVING IN.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
AT KCLT /09Z UPDATE/...PATCHY VFR STRATOCU OVER THE FOOTHILLS AND
WRN PIEDMONT WILL LIKELY LAST INTO THE MORNING. OBS SUGGEST A FEW
LOWER CLOUDS ARE UNDERNEATH THE MAIN DECK AND I CANNOT RULE OUT
BRIEF RESTRICTIONS ENTIRELY THRU DAYBREAK. GUIDANCE PERFORMING
POORLY AND NOT PROVIDING MUCH CONFIDENCE...BUT FEEL VFR LIKELY TO
CONTINUE. SCT VFR CUMULUS WILL BE THE DOMINANT CLOUDS FRI. LIGHT ENE
WINDS SHOULD VEER TO SE BY AFTN PER 06Z NAM AND CONSENSUS OF
PREVIOUS NAM/GFS RUNS.
ELSEWHERE...EASTERLY UPSLOPE FLOW NORTH OF WEAK COLD FRONT WILL
SUPPORT CLOUDS OVERNIGHT. RESTRICTIONS ARE ESPECIALLY FAVORED NEAR
THE BLUE RIDGE. GUIDANCE CONSENSUS DOES BRING MVFR CIG TO ALL SITES
EXCEPT KAVL WHERE IFR STILL EXPECTED. MTN VALLEY FOG LIKELY ONCE
AGAIN WITH VERY HUMID CONTDITIONS IN PLACE. KHKY SAW A PERIOD OF HVY
RA THU EVENING AND THE WET SOILS THERE WILL LIKELY SUPPORT IFR FOG
AS WELL. CIGS SHOULD BE SLOWER TO LIFT THE LOWER THEY BOTTOM
OUT...BUT WITH MOST SITES STAYING MVFR RESTRICTIONS SHOULD LIFT BY
MID MORNING AT THE LATEST. VFR CU WILL PERSIST THRU THE DAY IN SOME
FASHION WITH THE BLUE RIDGE AGAIN FAVORABLE FOR TS DEVELOPMENT.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY
THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN
VALLEYS AND WHERE RAIN FELL THE DAY BEFORE.
CONFIDENCE TABLE...
09-15Z 15-21Z 21-03Z 03-09Z
KCLT HIGH 89% HIGH 100% HIGH 100% HIGH 100%
KGSP LOW 58% HIGH 95% HIGH 100% HIGH 100%
KAVL MED 75% HIGH 88% HIGH 100% HIGH 91%
KHKY MED 75% HIGH 98% HIGH 100% HIGH 83%
KGMU MED 62% HIGH 95% HIGH 100% HIGH 100%
KAND MED 78% HIGH 96% 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_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...WIMBERLEY
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
427 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST
EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND
WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE
NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE
RETURNS ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
415 AM UPDATE...PRECIP COVERAGE HAS INCREASED OVER THE PAST HOUR AS
SUGGESTED BY EARLIER HRRR RUNS...HOWEVER NOT QUITE AS EXPECTED.
EASTERLY FLOW DOES CONTINUE TO PLAY A PART IN DRIVING LIGHT SHOWER
ACTIVITY IN THE FOOTHILLS...BUT STRONGER CELLS NOW FAVOR THE WRN
PORTION OF THE UPSTATE WHERE SPC MESOANALYSIS INDICATES GREATEST SFC
INSTABILITY IS PRESENT LIKELY DUE TO HIGHER DEWPOINTS. MAINTAINED
POP MENTION ALL ALONG THE BLUE RIDGE BUT NOW FEATURE BEST CHANCES IN
THE UPSTATE. RAIN RATES ARE RATHER HIGH AND REFLECTIVE OF ABUNDANT
MOISTURE...BUT CELL MOTION SO FAR HAS BEEN ENOUGH TO PRECLUDE FLASH
FLOOD THREAT. LLVL FLOW SHOWN TO WEAKEN SLIGHTLY TOWARD DAWN ON 06Z
NAM SO IT IS WISE TO CONTINUE TO MONITOR CLOSELY.
AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION
WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL
LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE
REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK
OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE
RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY
CORRESPONDINGLY GREATER.
UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER
THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS
THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO
MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW
CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS
CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST
CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER
THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 225 AM FRI...THE CWFA WILL REMAIN IN A WEAKNESS BETWEEN THE
RIDGING OVER THE CENTRAL CONUS AND THE ATLANTIC. THIS ALLOWS WEAK
SHORT WAVES MOVING THRU THE WESTERLIES TO DIG A SHALLOW TROF OVER
THE ERN CONUS EARLY IN THE PERIOD AND A STRONGER TROF BY MONDAY AS
AN UPPER LOW MOVES INTO THE GREAT LAKES REGION. WEAK S TO SWLY LOW
LEVEL FLOW KEEPS COPIOUS MOISTURE OVER THE AREA WITH PW VALUES AS
HIGH AS 2 INCHES. THIS COMBINED WITH MODERATE INSTABILITY WILL LEAD
TO DIURNAL CONVECTION BOTH SAT AND SUN AFTERNOONS. COVERAGE BOTH
DAYS WILL FAVOR THE MTNS WITH LOWER...BUT STILL SCT...CHC OVER THE
PIEDMONT. HIGHS WILL BE NEARLY STEADY NEAR NORMAL BOTH DAYS WITH
LOWS NEARLY STEADY ABOUT 5 DEGREES ABOVE NORMAL.
A WEAK FRONT MOVES IN WITH THE STRONGER TROF ON MON. EVEN WITH THE
FRONT AND TROF...CONVECTIVE COVERAGE WILL FAVOR THE MTNS AND TAPER
OFF TO THE PIEDMONT. HIGHS WILL BE NEAR TO SLIGHTLY ABOVE NORMAL.
WITH COPIOUS MOISTURE AND SLOW MOVING STORMS...HEAVY RAINFALL IS
POSSIBLE...POTENTIALLY LEADING TO ISOLATED FLASH FLOODING EACH DAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 310 AM FRI...AN UPPER TROF STARTS OUT OVER THE ERN CONUS ON
TUE THEN SLIDES OFF SHORE WED. THE CWFA REMAINS IN LIGHT NWLY FLOW
THRU THE END OF THE PERIOD WITH LITTLE IN THE WAY OF SHORT WAVE
ACTIVITY DROPPING THRU THE FLOW. AT THE SFC...A COLD FRONT STARTS
OUT OVER THE AREA TUE THEN SLIDES SOUTH AND EAST OF THE AREA WED AS
HIGH PRESSURE BUILDS IN FROM THE NW THU. ALL THIS LEADS TO DIURNAL
SCT CONVECTION TUE. THERE IS SOME INDICATION THAT MOISTURE COULD
LINGER OVER THE SAV RIVER VALLEY OR SWRN NC MTNS ON WED WITH DRIER
AIR MOVING IN ELSEWHERE. HOWEVER...HAVE KEPT FCST DRY FOR NOW. DRY
FCST CONTINUES THU. TEMPERATURES FALL BELOW NORMAL WITH COOLER HIGH
PRESSURE MOVING IN.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
AT KCLT...CLOUDS WILL CONTINUE TO RESULT OVERHEAD AS LLVL EASTERLY
FLOW PERSISTS INTO TOMORROW. GUIDANCE NOT PROVIDING A CLEAR SIGNAL
BUT MODELS GENERALLY HAVE OVERDONE CIGS SO FAR...SO HAVE KEPT VFR
THRU DAYBREAK...WITH HIGHER CONFIDENCE FOR VFR THEREAFTER. SCT VFR
CUMULUS WILL BE THE DOMINANT CLOUDS FRI. LIGHT ENE WINDS SHOULD VEER
TO SE BY AFTN.
ELSEWHERE...EASTERLY UPSLOPE FLOW NORTH OF WEAK COLD FRONT WILL
SUPPORT CLOUDS OVERNIGHT. RESTRICTIONS ARE ESPECIALLY FAVORED NEAR
THE BLUE RIDGE. GUIDANCE CONSENSUS DOES BRING MVFR CIG TO ALL SITES
EXCEPT KAVL WHERE IFR STILL EXPECTED. MTN VALLEY FOG LIKELY ONCE
AGAIN WITH VERY HUMID CONTDITIONS IN PLACE. KHKY SAW A PERIOD OF HVY
RA THU EVENING AND THE WET SOILS THERE WILL LIKELY SUPPORT IFR FOG
AS WELL. CIGS SHOULD BE SLOWER TO LIFT THE LOWER THEY BOTTOM
OUT...BUT WITH MOST SITES STAYING MVFR RESTRICTIONS SHOULD LIFT BY
MID MORNING AT THE LATEST. VFR CU WILL PERSIST THRU THE DAY IN SOME
FASHION WITH THE BLUE RIDGE AGAIN FAVORABLE FOR TS DEVELOPMENT.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY
THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN
VALLEYS AND WHERE RAIN FELL THE DAY BEFORE.
CONFIDENCE TABLE...
08-14Z 14-20Z 20-02Z 02-08Z
KCLT HIGH 87% HIGH 100% HIGH 100% HIGH 100%
KGSP MED 66% HIGH 93% HIGH 100% HIGH 100%
KAVL MED 76% HIGH 87% HIGH 100% HIGH 93%
KHKY HIGH 80% HIGH 93% HIGH 100% HIGH 87%
KGMU MED 73% HIGH 93% HIGH 100% HIGH 100%
KAND HIGH 84% HIGH 97% 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_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...WIMBERLEY
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
153 AM EDT FRI AUG 30 2013
.SYNOPSIS...
HIGH PRESSURE WILL NOSE IN FROM THE NORTH ON FRIDAY...BUT WITH A
MOIST EASTERLY FLOW IN PLACE. WEAK HIGH PRESSURE ALONG WITH
SOUTHERLY FLOW WILL LINGER THROUGH THE WEEKEND. A COLD FRONT WILL
APPROACH FROM THE NORTHWEST ON MONDAY...CROSS THE AREA MONDAY NIGHT
INTO TUESDAY...WITH DRY HIGH PRESSURE RETURNING ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TODAY/...
1 AM UPDATE...LLVL EASTERLY FLOW NORTH OF FRONTAL BOUNDARY...NOW
STRETCHING ACROSS CENTRAL GA AND SRN SC...CONTINUES TO SUPPORT
CONVECTIVE PRECIP NEAR THE BLUE RIDGE WITH A FEW HUNDRED JOULES OF
MLCAPE STILL AVAILABLE. 03Z HRRR PICKED UP RECENT ACTIVITY AND SHOWS
IT DIMINISHING WITH A SECOND WAVE FIRING UP AS MOISTURE CONTINUES TO
COLLECT AND FLOW VEERS SLIGHTLY BECOMING MORE PERPENDICULAR TO THE
MTN CHAIN. THAT SEEMS LIKE A REASONABLE ASSUMPTION AS CLOUD COVER
ALREADY IS INCREASING IN PORTIONS OF THE CENTRAL/NRN MTNS PER
SATELLITE FOG PRODUCT. ADJUSTED POPS TO TAKE THE SC ACTIVITY ON A
SWLY COURSE...DIMINISHING OVER THE NEXT COUPLE HRS BEFORE WHOLE BLUE
RIDGE SEES UPTICK.
REMAINDER OF PREV DISCUSSION...FRIDAY...DRIER AIR WILL CONTINUE TO
ADVECT SW ACROSS THE FOOTHILL AND PIEDMONT REGIONS. THE MTN
ENVIRONMENT MAY POOL HIGHER DEWPOINTS...SUPPORTING WEAK INSTABILITY.
I WILL KEEP A MENTION OF SCHC TO CHC CONVECTION ACROSS THE MTNS.
EAST...I WILL REDUCE POPS BELOW SCHC. FRESH CAA SHOULD KEEP HIGH
TEMPERATURES ONE TO TWO DEGREES BELOW NORMAL.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY/...
AS OF 200 PM EDT THU...THE WESTERN EXTENSION OF THE BERMUDA HIGH
WILL WEAKLY DOMINATE THE WEATHER REGIME THROUGH THE WEEKEND. IN THE
UPPER LEVELS...AN UPPER RIDGE TO THE WEST AND WEAK TROUGHING TO OUR
NORTH WILL RESULT IN WEAKLY DIFLUENT FLOW OVER THE SE U.S. WITH A
WEAK SHORT WAVE TRAVERSING THE REGION ON SUN. MODEL TIME HEIGHTS
INDICATE THAT MOISTURE WILL BE PLENTIFUL WITH PWATS AROUND 1.75
INCHES. THIS WILL SET THE STAGE FOR DIURNALLY DRIVEN THUNDERSTORMS
TO DEVELOP BOTH SAT AND SUN AFTERNOONS. ON SAT...THE MOST COVERAGE
WILL BE OVER THE CENTRAL AND SOUTHERN NC MOUNTAINS...INTO THE
WESTERN UPSTATE AND NE GA WHERE WEAK UPSLOPE FLOW WILL EXIST. ON
SUNDAY AFTERNOON...EXPECT COVERAGE TO BE GREATER THAN ON SAT WITH
NUMEROUS SHOWERS/STORMS OVER THE MOUTNAINS/FOOTHILLS WITH SCATTERED
STORMS OUT OVER THE PIEDMONT AS A WEAK SHORT WAVE MOVES THROUGH.
WITH WEAK FLOW ALOFT AND HIGH PWATS...THE MAIN THREAT OVER THE
WEEKEND WILL BE FOR LOCALLY HEAVY RAIN AND LOCALIZED FLASH FLOODING.
MAX TEMPS BOTH SAT AND SUN WILL TOP OUT NEAR CLIMO.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM EDT THU...UPPER HEIGHTS ARE FORECAST TO FALL ACROSS THE
SE U.S. THE FIRST PART OF THE NEW WORK WEEK AS AN EASTERN U.S. LONGWAVE
TROUGH DEVELOPS. LAPSE RATES WILL IMPROVE ON MONDAY AS A COLD FRONT
APPROACHES FROM THE WEST AND UPPER LEVEL HEIGHTS FALL. EXPECT THAT
THE COVERAGE OF AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS WILL BE
NUMEROUS OVER THE MOUNTAINS WITH SCATTERED STORMS OUT OVER THE
PIEDMONT. LOW END SEVERE AND FLASH FLOOD THREATS WILL EXIST MON
AFTERNOON INTO THE EVENING HOURS SUPPORTED BY CIPS WARM SEASON
ANALOGS.
THE COLD FRONT WILL CROSS THE REGION MONDAY NIGHT INTO TUESDAY.
SHEAR AND INSTABILITY IN THE PROFILES DO NOT LOOK PARTICULARLY
THREATENING...ESPECIALLY IN LIGHT OF THE THE UNFAVORABLE TIME OF
FRONTAL PASSAGE. SOME LINGERING INSTABILITY ESPECIALLY OVER THE
PIEDMONT AREAS COULD ALLOW FOR SOME SHOWERS/THUNDERSTORMS ON
TUE...BUT GENERALLY EXPECT LOWERING DEWPOINTS AND AND LOWERING POPS
ON TUE. HIGH PRESSURE IS FORECAST TO BUILD OVER THE REGION ON WED
AND THU PRODUCING GENERALLY DRY CONDITIONS AND TEMPS A CATEGORY SHY
OF NORMAL.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AT KCLT...CLOUDS WILL CONTINUE TO RESULT OVERHEAD AS LLVL EASTERLY
FLOW PERSISTS INTO TOMORROW. GUIDANCE NOT PROVIDING A CLEAR SIGNAL
BUT MODELS GENERALLY HAVE OVERDONE CIGS SO FAR...SO HAVE KEPT VFR
THRU DAYBREAK...WITH HIGHER CONFIDENCE FOR VFR THEREAFTER. SCT VFR
CUMULUS WILL BE THE DOMINANT CLOUDS FRI. LIGHT ENE WINDS SHOULD VEER
TO SE BY AFTN.
ELSEWHERE...EASTERLY UPSLOPE FLOW NORTH OF WEAK COLD FRONT WILL
SUPPORT CLOUDS OVERNIGHT. RESTRICTIONS ARE ESPECIALLY FAVORED NEAR
THE BLUE RIDGE. GUIDANCE CONSENSUS DOES BRING MVFR CIG TO ALL SITES
EXCEPT KAVL WHERE IFR STILL EXPECTED. MTN VALLEY FOG LIKELY ONCE
AGAIN WITH VERY HUMID CONTDITIONS IN PLACE. KHKY SAW A PERIOD OF HVY
RA THU EVENING AND THE WET SOILS THERE WILL LIKELY SUPPORT IFR FOG
AS WELL. CIGS SHOULD BE SLOWER TO LIFT THE LOWER THEY BOTTOM
OUT...BUT WITH MOST SITES STAYING MVFR RESTRICTIONS SHOULD LIFT BY
MID MORNING AT THE LATEST. VFR CU WILL PERSIST THRU THE DAY IN SOME
FASHION WITH THE BLUE RIDGE AGAIN FAVORABLE FOR TS DEVELOPMENT.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY
THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN
VALLEYS AND WHERE RAIN FELL THE DAY BEFORE.
CONFIDENCE TABLE...
06-12Z 12-18Z 18-24Z 00-06Z
KCLT HIGH 91% HIGH 91% HIGH 100% HIGH 100%
KGSP MED 74% MED 78% HIGH 100% HIGH 100%
KAVL MED 79% HIGH 80% HIGH 100% HIGH 97%
KHKY MED 68% HIGH 88% HIGH 100% HIGH 88%
KGMU HIGH 86% HIGH 82% HIGH 100% HIGH 100%
KAND HIGH 91% 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_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JOH
NEAR TERM...NED/WIMBERLEY
SHORT TERM...LG
LONG TERM...LG
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
150 AM EDT FRI AUG 30 2013
.SYNOPSIS...
A WEAK COLD FRONT WILL MOVE SOUTH ACROSS THE REGION TODAY. HIGH
PRESSURE WILL NOSE IN FROM THE NORTH ON FRIDAY...BUT WITH A MOIST
EASTERLY FLOW IN PLACE. WEAK HIGH PRESSURE ALONG WITH SOUTHERLY FLOW
WILL LINGER THROUGH THE WEEKEND. A COLD FRONT WILL APPROACH FROM THE
NORTHWEST ON MONDAY...CROSS THE AREA MONDAY NIGHT INTO
TUESDAY...WITH DRY HIGH PRESSURE RETURNING ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TODAY/...
1 AM UPDATE...LLVL EASTERLY FLOW NORTH OF FRONTAL BOUNDARY...NOW
STRETCHING ACROSS CENTRAL GA AND SRN SC...CONTINUES TO SUPPORT
CONVECTIVE PRECIP NEAR THE BLUE RIDGE WITH A FEW HUNDRED JOULES OF
MLCAPE STILL AVAILABLE. 03Z HRRR PICKED UP RECENT ACTIVITY AND SHOWS
IT DIMINISHING WITH A SECOND WAVE FIRING UP AS MOISTURE CONTINUES TO
COLLECT AND FLOW VEERS SLIGHTLY BECOMING MORE PERPENDICULAR TO THE
MTN CHAIN. THAT SEEMS LIKE A REASONABLE ASSUMPTION AS CLOUD COVER
ALREADY IS INCREASING IN PORTIONS OF THE CENTRAL/NRN MTNS PER
SATELLITE FOG PRODUCT. ADJUSTED POPS TO TAKE THE SC ACTIVITY ON A
SWLY COURSE...DIMINISHING OVER THE NEXT COUPLE HRS BEFORE WHOLE BLUE
RIDGE SEES UPTICK.
REMAINDER OF PREV DISCUSSION...FRIDAY...DRIER AIR WILL CONTINUE TO
ADVECT SW ACROSS THE FOOTHILL AND PIEDMONT REGIONS. THE MTN
ENVIRONMENT MAY POOL HIGHER DEWPOINTS...SUPPORTING WEAK INSTABILITY.
I WILL KEEP A MENTION OF SCHC TO CHC CONVECTION ACROSS THE MTNS.
EAST...I WILL REDUCE POPS BELOW SCHC. FRESH CAA SHOULD KEEP HIGH
TEMPERATURES ONE TO TWO DEGREES BELOW NORMAL.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY/...
AS OF 200 PM EDT THU...THE WESTERN EXTENSION OF THE BERMUDA HIGH
WILL WEAKLY DOMINATE THE WEATHER REGIME THROUGH THE WEEKEND. IN THE
UPPER LEVELS...AN UPPER RIDGE TO THE WEST AND WEAK TROUGHING TO OUR
NORTH WILL RESULT IN WEAKLY DIFLUENT FLOW OVER THE SE U.S. WITH A
WEAK SHORT WAVE TRAVERSING THE REGION ON SUN. MODEL TIME HEIGHTS
INDICATE THAT MOISTURE WILL BE PLENTIFUL WITH PWATS AROUND 1.75
INCHES. THIS WILL SET THE STAGE FOR DIURNALLY DRIVEN THUNDERSTORMS
TO DEVELOP BOTH SAT AND SUN AFTERNOONS. ON SAT...THE MOST COVERAGE
WILL BE OVER THE CENTRAL AND SOUTHERN NC MOUNTAINS...INTO THE
WESTERN UPSTATE AND NE GA WHERE WEAK UPSLOPE FLOW WILL EXIST. ON
SUNDAY AFTERNOON...EXPECT COVERAGE TO BE GREATER THAN ON SAT WITH
NUMEROUS SHOWERS/STORMS OVER THE MOUTNAINS/FOOTHILLS WITH SCATTERED
STORMS OUT OVER THE PIEDMONT AS A WEAK SHORT WAVE MOVES THROUGH.
WITH WEAK FLOW ALOFT AND HIGH PWATS...THE MAIN THREAT OVER THE
WEEKEND WILL BE FOR LOCALLY HEAVY RAIN AND LOCALIZED FLASH FLOODING.
MAX TEMPS BOTH SAT AND SUN WILL TOP OUT NEAR CLIMO.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM EDT THU...UPPER HEIGHTS ARE FORECAST TO FALL ACROSS THE
SE U.S. THE FIRST PART OF THE NEW WORK WEEK AS AN EASTERN U.S. LONGWAVE
TROUGH DEVELOPS. LAPSE RATES WILL IMPROVE ON MONDAY AS A COLD FRONT
APPROACHES FROM THE WEST AND UPPER LEVEL HEIGHTS FALL. EXPECT THAT
THE COVERAGE OF AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS WILL BE
NUMEROUS OVER THE MOUNTAINS WITH SCATTERED STORMS OUT OVER THE
PIEDMONT. LOW END SEVERE AND FLASH FLOOD THREATS WILL EXIST MON
AFTERNOON INTO THE EVENING HOURS SUPPORTED BY CIPS WARM SEASON
ANALOGS.
THE COLD FRONT WILL CROSS THE REGION MONDAY NIGHT INTO TUESDAY.
SHEAR AND INSTABILITY IN THE PROFILES DO NOT LOOK PARTICULARLY
THREATENING...ESPECIALLY IN LIGHT OF THE THE UNFAVORABLE TIME OF
FRONTAL PASSAGE. SOME LINGERING INSTABILITY ESPECIALLY OVER THE
PIEDMONT AREAS COULD ALLOW FOR SOME SHOWERS/THUNDERSTORMS ON
TUE...BUT GENERALLY EXPECT LOWERING DEWPOINTS AND AND LOWERING POPS
ON TUE. HIGH PRESSURE IS FORECAST TO BUILD OVER THE REGION ON WED
AND THU PRODUCING GENERALLY DRY CONDITIONS AND TEMPS A CATEGORY SHY
OF NORMAL.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AT KCLT...CLOUDS WILL CONTINUE TO RESULT OVERHEAD AS LLVL EASTERLY
FLOW PERSISTS INTO TOMORROW. GUIDANCE NOT PROVIDING A CLEAR SIGNAL
BUT MODELS GENERALLY HAVE OVERDONE CIGS SO FAR...SO HAVE KEPT VFR
THRU DAYBREAK...WITH HIGHER CONFIDENCE FOR VFR THEREAFTER. SCT VFR
CUMULUS WILL BE THE DOMINANT CLOUDS FRI. LIGHT ENE WINDS SHOULD VEER
TO SE BY AFTN.
ELSEWHERE...EASTERLY UPSLOPE FLOW NORTH OF WEAK COLD FRONT WILL
SUPPORT CLOUDS OVERNIGHT. RESTRICTIONS ARE ESPECIALLY FAVORED NEAR
THE BLUE RIDGE. GUIDANCE CONSENSUS DOES BRING MVFR CIG TO ALL SITES
EXCEPT KAVL WHERE IFR STILL EXPECTED. MTN VALLEY FOG LIKELY ONCE
AGAIN WITH VERY HUMID CONTDITIONS IN PLACE. KHKY SAW A PERIOD OF HVY
RA THU EVENING AND THE WET SOILS THERE WILL LIKELY SUPPORT IFR FOG
AS WELL. CIGS SHOULD BE SLOWER TO LIFT THE LOWER THEY BOTTOM
OUT...BUT WITH MOST SITES STAYING MVFR RESTRICTIONS SHOULD LIFT BY
MID MORNING AT THE LATEST. VFR CU WILL PERSIST THRU THE DAY IN SOME
FASHION WITH THE BLUE RIDGE AGAIN FAVORABLE FOR TS DEVELOPMENT.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY
THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN
VALLEYS AND WHERE RAIN FELL THE DAY BEFORE.
CONFIDENCE TABLE...
05-11Z 11-17Z 17-23Z 23-05Z
KCLT HIGH 98% HIGH 85% HIGH 100% HIGH 100%
KGSP MED 75% MED 70% HIGH 100% HIGH 100%
KAVL HIGH 84% MED 79% HIGH 99% HIGH 100%
KHKY MED 76% HIGH 83% HIGH 100% HIGH 91%
KGMU HIGH 92% MED 76% HIGH 100% HIGH 100%
KAND HIGH 98% MED 70% 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_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JOH
NEAR TERM...NED/WIMBERLEY
SHORT TERM...LG
LONG TERM...LG
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION...UPDATED
NWS SPOKANE WA
1035 PM PDT Thu Aug 29 2013
.SYNOPSIS...
Warm late-summer weather is expected over the Inland Northwest
through the upcoming holiday weekend. The passage of a cold front
late tonight will deliver a few showers and thunderstorms with a
small chance returning on Friday to the for a small portion of
northeast Washington and the Idaho Panhandle. The Labor Day
weekend is looking warmer than average with an abundance of
sunshine. A transition to a showery weather pattern is expected to
begin Monday and could persist through much of next week.
&&
.DISCUSSION...
Update this evening is to freshen the shower and thunderstorm
potential. The fast moving negatively tilted shortwave has quickly
moved out of the area and we are currently void of any showers and
thunderstorms in our area. There are some pretty decent showers
and thunderstorms developing across western WA and OR and may move
up the Cascades later this evening. So have taken out all evening
weather wording except for in the Cascades. Cold front passes
overnight. HRRR suggests a line of showers and possible
thunderstorms developing from eastern Columbia Basin after
midnight and moving into eastern WA and ID Panhandle overnight
into the early morning hours on Friday. /Nisbet
&&
.AVIATION...
06Z TAFS: Cold front passes overnight with a thin line of showers
and an isolated thunderstorm possible...impacting KGEG...KSFF...KCOE
btwn 07-12z. Post frontal southwesterly winds 10-15 mph with gusts
up to 25 mph can be expected Friday afternoon. VFR conditions
expected at all TAF sites.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 59 78 56 82 57 91 / 20 10 0 0 0 0
Coeur d`Alene 57 78 54 81 53 90 / 20 20 0 0 0 0
Pullman 53 78 48 83 49 93 / 10 10 0 0 0 0
Lewiston 64 86 59 89 61 99 / 10 10 0 0 0 0
Colville 56 83 50 85 49 93 / 20 10 0 0 0 0
Sandpoint 54 77 47 79 45 86 / 20 20 0 0 0 0
Kellogg 56 75 53 80 53 88 / 10 20 0 0 0 0
Moses Lake 58 84 54 86 56 93 / 10 10 0 0 0 0
Wenatchee 62 82 59 84 61 89 / 10 0 0 0 0 0
Omak 58 82 55 85 55 91 / 10 10 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
320 AM CDT FRI AUG 30 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 320 AM CDT FRI AUG 30 2013
MAIN FORECAST CONCERNS INCLUDE SHOWER/THUNDERSTORM CHANCES
TODAY...THEN AREAS OF FOG LATE TONIGHT.
WATER VAPOR IMAGERY SHOWING A WELL-DEFINED MID-LEVEL TROUGH MAKING
ITS WAY THROUGH WESTERN LAKE SUPERIOR/NORTHWEST WI. AT THE
SURFACE...A COLD FRONT EXTENDED FROM FROM WESTERN LAKE SUPERIOR TO
JUST EAST OF THE TWIN CITIES...AND INTO SOUTHWEST MN. RADAR MOSAIC
SHOWING ISOLATED-SCATTERED ELEVATED SHOWERS AND THUNDERSTORMS ALONG
THIS FRONTAL BOUNDARY AS IT SINKS SOUTHEASTWARD INTO THE AREA.
FOR TODAY...WILL BE WATCHING THE COLD FRONT AS IT MAKES PASSAGE
THROUGH THE AREA. SHOULD BE SOME ONGOING ISOLATED-SCATTERED
SHOWERS/THUNDERSTORMS ALONG THE FRONT AS IT PRESSES INTO THE AREA.
GFS/NAM DETERMINISTIC MODELS ALONG WITH THE HRRR/HIRES ARW-EAST WRF
MODELS SHOWING THIS CONVECTION UPSCALING A BIT ACROSS PORTIONS OF
FAR SOUTHERN WI INTO NORTHEAST IA THIS AFTERNOON AS THE FRONT PUSHES
INTO A VERY MUGGY AIRMASS WITH 0-1KM MLCAPE OF 2500-3500J/KG ALONG
WITH 0-3KM BULK SHEAR IN THE 20 TO 30KT RANGE. BASED ON THIS
SIGNAL...CANNOT RULE OUT THE THREAT FOR A FEW SEVERE THUNDERSTORMS
ACROSS THIS AREA WITH DAMAGING WINDS AND HAIL BEING THE MAIN
THREATS. ALSO WILL BE GOING WITH A HEAT ADVISORY THIS AFTERNOON FOR
PORTIONS OF FAR SOUTHWEST WI INTO NORTHEAST IA BASED ON HEAT
INDICES CREEPING INTO THE 100-105 DEGREE RANGE. OTHERWISE BEHIND
THE FRONT/ACROSS THE REST OF THE FORECAST AREA...LOOK FOR SOME
RELIEF TO THE MUGGY CONDITIONS WITH DEW POINTS LOWERING INTO THE
65-70 DEGREE RANGE AND TEMPERATURES TOPPING OFF IN THE 80-90 DEGREE
RANGE.
LOOK FOR THE COLD FRONT/SHOWER AND THUNDERSTORM CHANCES TO PUSH
SOUTHWARD OUT OF THE AREA THIS EVENING WITH A RIDGE OF HIGH PRESSURE
BUILDING OVERHEAD THROUGH THE OVERNIGHT HOURS. LIGHT-CALM WINDS
ALONG WITH COOLING LOWER BOUNDARY LAYER WILL SET UP FAVORABLE
CONDITIONS FOR AREAS OF FOG...MAINLY ALONG AND NORTH OF I-94 WHERE
RECENT RAINS HAVE FALLEN AND IN RIVER VALLEYS ACROSS THE REST OF THE
AREA. OVERNIGHT LOWS ARE EXPECTED TO DROP OFF IN THE UPPER 50S TO
THE MIDDLE AND UPPER 60S.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 320 AM CDT FRI AUG 30 2013
NORTHWEST FLOW ALOFT BRINGS ANOTHER FAIRLY VIGOROUS MID-LEVEL
SHORTWAVE TROUGH/SURFACE COLD FRONT INTO THE REGION SATURDAY THROUGH
SUNDAY FOR A DECENT CHANCE OF SHOWERS AND THUNDERSTORMS. TIMING OF
THE FRONTAL PASSAGE BY LATE MORNING/EARLIER IN THE AFTERNOON SHOULD
MITIGATE SEVERE POTENTIAL. WILL HAVE TO KEEP AN EYE ON THE TIMING OF
THE FRONT AS ANY SLOWING TO LATER IN THE AFTERNOON COULD INCREASE
THE SEVERE POTENTIAL. OTHERWISE...HIGH SUNDAY ARE EXPECTED TO TOP
OFF ONLY IN THE MIDDLE 70S TO THE MIDDLE 80S...OR JUST A FEW DEGREES
ABOVE NORMAL. COOLER TEMPERATURES ON TAP FOR SUNDAY NIGHT BEHIND THE
FRONTAL PASSAGE WITH OVERNIGHT LOWS DROPPING INTO THE MIDDLE TO UPPER 50S.
FOR MONDAY THROUGH THURSDAY...GFS AND ECMWF SHOW THE MIDDLE/UPPER
LEVEL RIDGE BUILDING ACROSS THE INTERMOUNTAIN WEST WITH OUR AREA IN
DRY NORTHWEST FLOW ALOFT. COOLER SHOT OF AIR WITH 850MB TEMPERATURES
IN THE 5-10C RANGE MOVES OVER THE AREA ON MONDAY FOR HIGHS IN THE
UPPER 60S TO THE MIDDLE 70S. TEMPERATURES LOOK TO HOLD RIGHT AROUND
NORMAL LEVELS FOR TUESDAY THROUGH THURSDAY WITH HIGHS IN THE MIDDLE
70S TO AROUND 80S AND OVERNIGHT LOWS MAINLY IN THE 50S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT
1143 PM CDT THU AUG 29 2013
AN AREA OF SURFACE LOW PRESSURE WAS OVER WESTERN LAKE SUPERIOR
LATE THIS EVENING WITH A COLD FRONT FROM NORTHEAST MINNESOTA INTO
SOUTHEAST SOUTH DAKOTA. ALMOST ALL THE CONVECTION IS NOW WELL OUT
AHEAD OF THE SURFACE LOW ALONG THE WARM FRONT OVER NORTHEAST
WISCONSIN. ONE LAST AREA OF CONVECTION JUST AHEAD OF THE COLD
FRONT OVER NORTHWEST WISCONSIN IS CLOSELY TIED TO THE UPPER LEVEL
SHORT WAVE TRACKING ACROSS MINNESOTA. THIS WAVE WILL CONTINUE TO
MOVE OFF TO THE EAST THROUGH THE NIGHT WITH THE AREA OF CONVECTION
SLIPPING TO THE SOUTHEAST. WILL BE INTERESTING TO SEE HOW FAR THIS
CONVECTION CAN SURVIVE AS IT GETS FARTHER AWAY FROM THE
WAVE...DEEPER INTO THE CAPPING AND WITH THE LOW LEVEL JET FEEDING
THE NORTHEAST WISCONSIN COMPLEX. EVEN IF IT DOES SURVIVE...CURRENT
MOVEMENT WOULD TAKE IT NORTHEAST OF BOTH TAF SITES. SOME
DIFFERENCES BETWEEN THE 31.00Z NAM AND 31.03Z RAP ON WHETHER THE
CAP WILL REMAIN IN PLACE AHEAD OF THE FRONT. THE NAM INDICATES IT
WILL WITH THE FRONT PASSING THROUGH DRY WHILE THE RAP WANTS TO
WEAKEN THE CAP WITH SOME SHOWERS FORMING ALONG AS IT PASSES
THROUGH. CURRENT SATELLITE SHOWS A GENERAL LACK OF CLOUDS ALONG
MUCH OF THE FRONT ACROSS CENTRAL AND SOUTHWEST MINNESOTA
INDICATING THE CAP IS STILL IN PLACE SO WILL LEAN TOWARD THE NAM
AND MAINTAIN CONTINUITY WITH THE FRONT PASSING THROUGH DRY WITH
JUST SOME SCATTERED CLOUDS ALONG IT. NORTHWEST WINDS BEHIND THE
FRONT WILL INCREASE TO AROUND 10 KNOTS DURING THE AFTERNOON BEFORE
DIMINISHING FRIDAY EVENING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY FROM 11 AM THIS MORNING TO 6 PM CDT THIS EVENING
FOR WIZ061.
MN...NONE.
IA...HEAT ADVISORY FROM 11 AM THIS MORNING TO 6 PM CDT THIS EVENING
FOR IAZ018-019-029-030.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1143 PM CDT THU AUG 29 2013
.SHORT TERM...(TONIGHT THROUGH FRIDAY TONIGHT)
ISSUED AT 328 PM CDT THU AUG 29 2013
MAIN FORECAST CONCERNS THIS PACKAGE...SHRA/TSRA CHANCES TONIGHT/
FRI...TEMPS/HEAT/HUMIDITY FRIDAY.
DATA ANALYSIS AT 18Z HAD HIGH PRESSURE OVER LOWER MI AND LOW
PRESSURE OVER EASTERN ND WITH TOUGHING FROM LK WINNIPEG TO EASTERN
CO. DIFFUSE/ILL-DEFINED WARM FRONT WAS LOCATED FROM THE ND LOW
TO NEAR THE MS RIVER THRU THE FCST AREA. MAIN FORCING/LIFT/MOISTURE
CONVERGENCE WAS INTO NORTHERN MN...WHERE A MATURE CONVECTIVE COMPLEX
WAS MOVING INTO WESTERN LK SUPERIOR. ACROSS WI/IA/REST OF MN...WARM
TEMPS IN THE 800-700MB LAYER CONTINUED TO CAP THE AIRMASS EARLY THIS
AFTERNOON...EVEN WITH SFC DEW POINTS IN THE UPPER 60S/LOW 70S AND
TEMPS IN THE MID 80S/LOW 90S. LAPS SOUNDINGS SHOWING CONVECTIVE TEMPS
IN THE 98F-108F RANGE.
NO BIG PROBLEMS NOTED WITH 29.12Z INITIALIZATIONS. GFS WITH ITS
USUAL SLIGHTLY OFF SFC DEW POINT ANALYSIS OVER THE MID/UPPER MS
VALLEY. SOLUTIONS REASONABLY SIMILAR FOR TONIGHT THRU FRI NIGHT
WITH THE MAIN FORCING/LIFT SHRA/TSRA CHANCE PASSING NORTH OF THE
FCST AREA THEN A WEAK COLD FRONT TO SLIDE ACROSS THE AREA FRI.
DPROG/DT OF 500MB HGTS AT 29.12Z SHOWED THE MODEL RUNS OF 27.12Z AND
28.12Z VERIFIED QUITE WELL ACROSS NOAM...WITH STRONGER OF EARLIER
RUNS BETTER ON THE SHORTWAVE APPROACHING LK WINNIPEG. TREND FAVORS
STRONGER OF EARLIER RUNS AS THE LK WINNIPEG WAVE CROSSES LK
SUPERIOR THRU TONIGHT...AND STRONGER WITH THE NEXT WAVE TO TOP THE
MID NOAM RIDGE MOVING INTO WA/SOUTHERN BC. TREND CONTINUES TO FAVOR
STRONGER/FASTER OF EARLIER MODELS AS THIS WAVE MOVES INTO SASKAT/
EASTERN MT BY 12Z SAT. CHECK OF OBS VS. MODEL DATA AT 18Z SHOWED ALL
TO BE REASONABLE WITH THE SFC MASS FIELDS OVER THE CENTRAL CONUS.
PER WV IMAGERY...NON-NAM MODELS LOOKED BETTER WITH THE SHORTWAVE
PASSING ACROSS SOUTHERN MANITOBA. MODELS ALL GENERALLY TOO FAR
SOUTH WITH THE 12-18Z PRECIP IN EASTERN MN/WESTERN WI...AND NOT
STRONG ENOUGH WITH THE TSRA COMPLEX NEAR KDLH. NO ONE MODEL LOOKED
PREFERRED THIS CYCLE. WITH A RATHER TIGHT CONSENSUS AMONG THE
MODELS...EVEN WITH THE TRENDS ON THE SHORTWAVES OF INTEREST...
FAVORED THE MODEL/ENSEMBLE CONSENSUS. SHORT-TERM FCST CONFIDENCE
IS GOOD THIS CYCLE.
IN THE SHORT TERM...FIRST SHORTWAVE TRACKS EAST/SOUTHEAST AND ACROSS
LK SUPERIOR TONIGHT. BULK OF FORCING/CONVERGENCE/LIFT WITH THIS
FEATURE...AND HIGHER SHRA/TSRA CHANCES PASS NORTHEAST OF OR JUST
CLIP THE NORTHEAST END OF THE FCST AREA. ATTENDANT SFC LOW/TROUGH
DRAGS A COLD FRONT INTO THE AREA LATER TONIGHT...TO NEAR A KAUW-KLSE-
KMCW LINE BY 12Z FRI. NOT MUCH FOR LOWER LEVEL THERMO-DYNAMIC
FORCING WITH THIS FRONT/BOUNDARY AS IT PUSHES INTO/ACROSS THE FCST
AREA LATE TONIGHT/FRI MORNING. SOME WEAK 925MB THETA-E CONVERGENCE...
BUT THESE PARCELS FIGHTING CIN TO 650MB OR NO CAPE AT ALL. THUS
MODELS ONLY GENERATE SOME ISOLATED/WDLY SCT SHRA/TSRA WITH THIS
FRONTAL PASSAGE. LEFT SOME 20-40 PERCENT SHRA/TSRA CHANCES OVER THE
NORTHEAST END OF THE FCST AREA TONIGHT. ONLY CARRIED 20 PERCENT
SHRA/TSRA CHANCES OVER THE CENTRAL/WEST PARTS OF THE FCST AREA WITH
THE FRONTAL PASSAGE LATE TONIGHT/FRI MORNING. LEFT SOME 20-40
PERCENT SHRA/TSRA CHANCES OVER THE SOUTHEAST HALF OF THE FCST AREA
FRI AFTERNOON INTO FRI EVENING...DUE TO PROXIMITY OF THE BOUNDARY AND
ML CAPE VALUES RISING INTO THE 1.5. TO 2.5 K J/KG RANGE. 0-6KM BULK
SHEAR IN THE 25-30KT RANGE FRI AFTERNOON...ISOLATED SEVERE STORMS
WITH A HAIL OR WIND THREAT CANNOT BE RULED OUT.
AHEAD OF THE FRONT...HEAT INDICES WILL AGAIN CLIMB INTO THE 90-100
RANGE OVER THE SOUTHEAST THIRD OF THE FCST AREA FRI AFTERNOON/EARLY
FRI EVENING. MAY YET NEED A HEAT ADVISORY FOR THE SOUTHEAST END OF
THE FCST AREA CENTERED ON FRI AFTERNOON...BUT IF SCT SHRA/TSRA
DEVELOP AND SKIES BECOME MORE CLOUDY THAN SUNNY...HEAT INDICES
WOULD NOT REACH 100...AT LEAST FOR MORE THAN AN HOUR AT ANY ONE SPOT.
WEAK BUBBLE HIGH SETTLES OVER THE AREA FRI NIGHT. WITH LIGHT WINDS...
CLEAR/MOSTLY CLEAR SKIES...COOLER 925-850MB TEMPS AND STRONG
RADIATIONAL COOLING EXPECTED...CONTINUED THE MENTION OF PATCHY TO
AREAS OF FOG IN GRIDS FOR LATER FRI NIGHT INTO EARLY SAT MORNING.
USED A MODEL/ENSEMBLE CONSENSUS OF LOWS/HIGHS FOR TONIGHT THRU FRI
NIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 328 PM CDT THU AUG 29 2013
MAIN FORECAST CONCERNS FOR SAT THRU SUN NIGHT...TEMPERATURES/HEAT
POTENTIAL SATURDAY...SHRA/TSRA CHANCES SAT NIGHT/SUN.
THE STRONGER/TREND WITH THE MT/SASKAT SHORTWAVE CONTINUES SAT/SAT
NIGHT AS IT MOVE INTO MN/WESTERN ONT BY 12Z SUN...THEN PASSES
ACROSS THE REGION SUN...PUSHING A RATHER STRONG COLD FRONT THRU THE
AREA. AGAIN WITH A RATHER TIGHT CONSENSUS/SHIFT BY ALL MODELS...
FAVORED THE MODEL/ENSEMBLE CONSENSUS FOR SAT THRU SUN NIGHT.
WEAK HIGH PRESSURE REMAINS OVER THE AREA SAT. WITH DIURNAL WARMING/
MIXING...AND SOME DRIER 925-850MB AIR OVER THE REGION...SFC DEW
POINTS LOOKING TO BE MORE IN THE LOW-MID 60S SAT AFTERNOON. SAT
AFTERNOON HEAT INDICES TRENDING TO TOP OUT MORE IN THE 85-90 RANGE...
FOR A LITTLE MORE RELIEF FROM THE RECENT HEAT/HUMIDITY. MOISTURE
TRANSPORT INCREASES INTO THE AREA SAT NIGHT WITH PW VALUES BACK IN
THE 1.5 INCH RANGE BY 12Z SUN. STRONGER/DEEPER LOWER LEVEL THERMO-
DYNAMIC FORCING INDICATED WITH APPROACH/PASSAGE OF THE TROUGH/FRONT
LATE SAT NIGHT/SUN MORNING. THIS ALONG WITH SOME 400-200MB PV
ADVECTION AHEAD OF THE STRONGER SHORTWAVE...AND MU CAPE VALUES OF
AROUND 1K J/KG LIFTING 900-800MB PARCELS. CONTINUED/RAISED SHRA/
TSRA CHANCES CENTERED ON LATE SAT NIGHT/SUN MORNING IN THE 30- 50
PERCENT RANGE. TRENDED SHRA/TSRA CHANCES DOWN SUN AFTERNOON WITH
PASSAGE OF THE FRONT/LIFT AND LOWER LEVEL COLD ADVECTION/DRYING
SPREADING SOUTHEAST ACROSS THE AREA. SOME BRISK/GUSTY NORTHWEST
WINDS SUN AFTERNOON WITH THE COLD ADVECTION AND MIXING TO AT LEAST
850MB. DRY/COOLER SUN NIGHT AS CAN HIGH PRESSURE SETTLES INTO THE
NORTHERN PLAINS/WESTERN GREAT LAKES AND 850MB TEMPS FALL INTO THE
8C-12C RANGE BY MON MORNING. AGAIN USED A MODEL/ENSEMBLE CONSENSUS
OF THE NUMERICAL GUIDANCE FOR HIGHS/LOWS SAT THRU SUN NIGHT.
FOR MONDAY/LABOR DAY THROUGH THURSDAY.../DAYS 4-7/...
LATEST MEDIUM RANGE MODEL RUNS REMAIN IN GOOD AGREEMENT MONDAY
WITH RATHER STRONG TROUGHING TO BE OVER ONT/GREAT LAKES AND RIDGING
TO BE BUILDING NORTHWARD INTO SASKAT/MANITOBA. GOOD CONSISTENCY FOR
HGTS TO RISE OVER THE REGION TUE AS THE TROUGHING MOVES INTO
EASTERN NOAM...BUT MN/WI/IA TO REMAIN UNDER RATHER STRONG NORTHWEST
FLOW ALOFT. 29.00Z WERE DIFFERENT FOR WED/THU...WITH STRENGTH OF
A SHORTWAVE TROUGH TO DROP DOWN THE EAST SIDE OF THE RIDGE AND
INTO THE EASTERN NOAM TROUGH. 29.12Z MODELS HAVE TRENDED TOWARD A
COMPROMISE ON THE TIMING/STRENGTH OF THIS FEATURE AND THE
TROUGHING OVER EASTERN NOAM WED/THU. 29.12Z GFS/ECMWF WITH BETTER
CONSENSUS ON THE NEXT TROUGHING MOVING INTO THE NORTHWEST
CONUS/WESTERN CAN ON DAYS 6/7 TOO. FCST CONFIDENCE GOOD FOR
MON/TUE THEN AVERAGE WED/THU.
STRONG PASSING COLD FROM SUNDAY USHERS A COOLER/DRIER CAN HIGH
PRESSURE SYSTEM INTO THE UPPER MIDWEST FOR MON/TUE. BY LABOR DAY
MORNING...925MB TEMPS IN THE 11C-14C RANGE ACROSS THE FCST AREA.
THESE TEMPS SLOWLY MODERATE THRU MON/TUE BUT ONLY RECOVER TO THE 19C-
21C RANGE BY TUE EVENING. MON/TUE STILL LOOKING LIKE A A COUPLE OF
COOLER...COMFORTABLE DAYS COMPARED TO THE PAST SEVERAL DAYS. LIKE
PREVIOUS FORECASTER STATED...MAY NEED A VALLEY FOG MENTION CENTERED
ON DAYBREAK TUE...BUT WILL LEAVE THAT OUT OF THE GRIDS FOR NOW GIVEN
THE SENSITIVITY OF VALLEY FOG TO LOWER LEVEL/BOUNDARY LAYER NUANCES.
EVEN WITH SHORTWAVE/TROUGH STRENGTH DIFFERENCES BY WED...BOTH GFS/
ECMWF PUSH A COLD FRONT SOUTHEAST ACROSS THE REGION WED. MOISTURE/
CAPE CONTINUE TO LOOK LIMITED AHEAD OF/WITH THIS FEATURE. SMALL
SHRA/TSRA CHANCE AT BEST WED BUT WILL LEAVE THIS PERIOD DRY FOR
NOW PER THE MODEL/ENSEMBLE CONSENSUS. NORTHWEST FLOW ALOFT SENDS
ANOTHER CAN HIGH SOUTH INTO THE REGION FOR THU BUT CORE OF THE
COOLEST 925-850MB AIR WITH THIS HIGH REMAINS NORTH/EAST OF THE
FCST AREA AS IT BUILDS IN. EVEN WITH SOME MODEL DIFFERENCES...
GUIDANCE HIGHS/LOWS FOR MON-THU NOT THAT DIFFERENT AND USED THE
MODEL/ENSEMBLE CONSENSUS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1143 PM CDT THU AUG 29 2013
AN AREA OF SURFACE LOW PRESSURE WAS OVER WESTERN LAKE SUPERIOR
LATE THIS EVENING WITH A COLD FRONT FROM NORTHEAST MINNESOTA INTO
SOUTHEAST SOUTH DAKOTA. ALMOST ALL THE CONVECTION IS NOW WELL OUT
AHEAD OF THE SURFACE LOW ALONG THE WARM FRONT OVER NORTHEAST
WISCONSIN. ONE LAST AREA OF CONVECTION JUST AHEAD OF THE COLD
FRONT OVER NORTHWEST WISCONSIN IS CLOSELY TIED TO THE UPPER LEVEL
SHORT WAVE TRACKING ACROSS MINNESOTA. THIS WAVE WILL CONTINUE TO
MOVE OFF TO THE EAST THROUGH THE NIGHT WITH THE AREA OF CONVECTION
SLIPPING TO THE SOUTHEAST. WILL BE INTERESTING TO SEE HOW FAR THIS
CONVECTION CAN SURVIVE AS IT GETS FARTHER AWAY FROM THE
WAVE...DEEPER INTO THE CAPPING AND WITH THE LOW LEVEL JET FEEDING
THE NORTHEAST WISCONSIN COMPLEX. EVEN IF IT DOES SURVIVE...CURRENT
MOVEMENT WOULD TAKE IT NORTHEAST OF BOTH TAF SITES. SOME
DIFFERENCES BETWEEN THE 31.00Z NAM AND 31.03Z RAP ON WHETHER THE
CAP WILL REMAIN IN PLACE AHEAD OF THE FRONT. THE NAM INDICATES IT
WILL WITH THE FRONT PASSING THROUGH DRY WHILE THE RAP WANTS TO
WEAKEN THE CAP WITH SOME SHOWERS FORMING ALONG AS IT PASSES
THROUGH. CURRENT SATELLITE SHOWS A GENERAL LACK OF CLOUDS ALONG
MUCH OF THE FRONT ACROSS CENTRAL AND SOUTHWEST MINNESOTA
INDICATING THE CAP IS STILL IN PLACE SO WILL LEAN TOWARD THE NAM
AND MAINTAIN CONTINUITY WITH THE FRONT PASSING THROUGH DRY WITH
JUST SOME SCATTERED CLOUDS ALONG IT. NORTHWEST WINDS BEHIND THE
FRONT WILL INCREASE TO AROUND 10 KNOTS DURING THE AFTERNOON BEFORE
DIMINISHING FRIDAY EVENING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
321 PM CDT WED AUG 28 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 321 PM CDT WED AUG 28 2013
THE MAIN FOCUS TONIGHT INTO TOMORROW IS WITH THE CHANCES OF
PRECIPITATION AND WHETHER ANY FOG WILL DEVELOP OVERNIGHT AGAIN.
THE UPPER LEVEL FLOW CONTINUES TO BE SHAPED BY BROAD RIDGING THAT
IS CENTERED OVER THE PLAINS AND EXTENDS FROM THE SOUTHEASTERN US
TO THE SOUTHWESTERN US. ANY PRECIPITATION HAS COME ALONG THE NORTHERN
PERIPHERY OF THIS RIDGE AS MID LEVEL SHORT WAVE TROUGHS TRACK
ALONG THE RIM. THERE CURRENTLY ARE A PAIR OF SHORT WAVE TROUGHS
THAT WILL NEED MONITORING INTO TOMORROW...ONE WEAK ONE IN THE
DAKOTAS/WESTERN MINNESOTA AND ANOTHER RUNNING INTO MONTANA. AT THE
SURFACE...A COLD FRONT HAS STALLED OUT ACROSS CENTRAL IOWA WITH
RIDGING ACROSS THE NORTHERN GREAT LAKES. DEW POINTS HAVE REALLY
POOLED ALONG THE NORTHERN SIDE OF THIS FRONT WITH MID/UPPER 70S
ANALYZED FROM CENTRAL ILLINOIS THROUGH EASTERN/NORTHERN IOWA.
EARLIER STRATUS HAS ALSO BECOME MORE MIXED AS THE DAY HAS GONE ON
TODAY...WHICH HAS LEAD TO SOME QUICK WARM UPS AS WELL.
GOING INTO TONIGHT...THE FIRST SHORTWAVE IN THE DAKOTAS/MINNESOTA
WILL PROPAGATE TO THE EAST AND WILL HELP TO LIFT THE FRONT BACK TO
THE NORTH AS A WARM FRONT ACROSS SOUTHERN MINNESOTA. THE 18.12Z
NAM/GFS AND 18.18Z RAP SHOWS THE POOL OF HIGHEST 0-3KM MUCAPE
LIFTING NORTH AS WELL IN MINNESOTA AND BECOMING ORIENTED MORE
NORTH TO SOUTH FROM CENTRAL MINNESOTA TO EASTERN IOWA OVERNIGHT.
THE BEST LOW LEVEL MOISTURE TRANSPORT APPEARS TO BE IN CENTRAL
MINNESOTA AS WELL WHERE THE STRONGER PUSH/CONVERGENCE IS FROM THE
SOUTH. HAVE KEPT SOME LOW CHANCES OF SHOWERS/STORMS OVERNIGHT IN
PORTIONS OF SOUTHEAST MINNESOTA/NORTHEAST IOWA TO ACCOUNT FOR
THIS...BUT CONFIDENCE IS NOT OVERLY HIGH THAT THE FORCING WILL BE
ENOUGH TO PRODUCE SOME CONVECTION.
THE HIGHER CHANCES FOR PRECIPITATION WILL COME ON THURSDAY AS THE
SECOND MID LEVEL SHORT WAVE TROUGH PROPAGATES EAST FROM MONTANA
THROUGH THE DAKOTAS ON TOWARD THE UPPER GREAT LAKES. IT APPEARS
THAT AN MCS WILL DEVELOP OVER THE DAKOTAS FROM THIS FEATURE AND
TRACK TO THE EAST INTO MINNESOTA TOMORROW MORNING. AS THE
SHORTWAVE ENTERS MINNESOTA/NORTHERN WISCONSIN LATE TOMORROW
MORNING/AFTERNOON...CONVECTION MAY DEVELOP ALONG THE WARM FRONT
WHICH WILL BE LIFTING TO THE NORTH AS A LOW MOVES INTO CENTRAL
MINNESOTA. WITH THE HIGH INSTABILITY ON THE ORDER OF 2000-4000
J/KG AND DECENT SHEAR...CAN NOT RULE OUT SOME SEVERE WEATHER
ACROSS NORTHERN WISCONSIN THE AFTERNOON HOURS WITH LARGE
HAIL/DAMAGING WINDS THE MAIN THREATS. NORTHERN WISCONSIN IS ALSO
THE LOCATION OF THE HIGHEST PRECIPITATION CHANCES AS THIS TROUGH
MOVES THROUGH GOING INTO THURSDAY NIGHT.
WITH LIGHT WINDS AND HIGH AMOUNTS OF LOW LEVEL MOISTURE STILL IN
THE REGION...CAN NOT RULE OUT SOME FOG TONIGHT...PARTICULARLY IN
WESTERN WISCONSIN WHICH WILL BE CLOSER TO THE HIGH AND FURTHER
FROM ANY CLOUD COVER.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 321 PM CDT WED AUG 28 2013
THE COMPLEX WILL MOVE THROUGH ON THURSDAY NIGHT WITH A COLD FRONT
DROPPING DOWN ACROSS THE REGION ON FRIDAY. THE 28.12Z NAM/GFS
FORECAST SOUNDINGS DIFFER ON THE AMOUNT OF CAPPING THAT WILL BE IN
PLACE AHEAD OF THIS FRONT WITH THE NAM SHOWING MORE OF IT AND THE
GFS LESS. THUS...THE NAM IS MAINLY DRY WITH THE FROPA WHILE THE
GFS PRODUCES SOME QPF. KEPT SOME PRECIPITATION CHANCES IN THERE
FOR NOW...MAINLY IN WESTERN WISCONSIN.
TEMPERATURES WARM UP AHEAD OF THIS FRONT WITH HIGHS GOING BACK
INTO THE 90S ACROSS MUCH OF NORTHEAST IOWA AND FAR SOUTHWEST
WISCONSIN. WITH HEAT INDICES AROUND 100F IN THE AFTERNOON...MAY
HAVE TO DO A HEAT ADVISORY FOR THIS REGION.
BEYOND THIS...A BIG PATTERN CHANGE IS ON THE WAY FOR SUNDAY AS A
MID LEVEL TROUGH DIGS DOWN FROM CANADA AND BRINGS A MUCH COOLER
AIR MASS DOWN INTO THE REGION. 850MB TEMPERATURES...WHICH
GENERALLY HAVE BEEN IN THE +15C TO +25C RANGE THE PAST WEEK...WILL
DROP TO ABOUT +7C SUNDAY NIGHT AFTER THE COLD FRONT SWINGS
THROUGH. WHILE STORMS LOOK POSSIBLE WITH THE COLD FRONT COMING
THROUGH...THE TIME OF THE DAY DOES NOT LOOK FAVORABLE FOR SEEING
SEVERE WEATHER AS THE FRONT WILL LIKELY COME THROUGH IN THE
MORNING BEFORE ANY HIGH INSTABILITY CAN BUILD. HIGH PRESSURE THEN
SETTLES IN FOR THE EARLY PART OF NEXT WEEK WITH MUCH COOLER AND
SEASONABLE TEMPERATURES ON TAP.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1220 PM CDT WED AUG 28 2013
EASTERLY WINDS IN THE SFC-850MB LAYER CONTINUE TO ADVECT MVFR
STRATUS DECKS WESTWARD ACROSS THE TAF SITES EARLY THIS AFTERNOON.
THESE CLOUDS/MOISTURE STUCK UNDER A MDT/STRONG INVERSION NEAR
900MB...MAKING THE CLOUDS MUCH MORE PERSISTENT THAN EARLIER THOUGHT.
WITH DIURNAL WARMING/MIXING...THE CLOUD DECK WILL SLOWLY BECOME
BKN-SCT THRU THE AFTERNOON. WITH A FRONTAL BOUNDARY JUST SOUTH OF
THE AREA AND THE MOISTURE TRAPPED UNDER THE INVERSION...SOME MVFR
CLOUDS LOOKING TO PERSIST WELL INTO TONIGHT AND LIKELY INTO THU.
DEBRIS CLOUDS FROM CONVECTION TO THE WEST TO SPREAD ACROSS THE AREA
TONIGHT. WITH THE HUMID LOW LEVEL AIRMASS AND GENERALLY LIGHT
WINDS...THESE HIGHER LEVEL CLOUDS SHOULD HELP KEEP FOG FROM BECOMING
WIDESPREAD AND DENSE LATE TONIGHT/EARLY THU MORNING. HOWEVER...
CONTINUED/ADDED MVFR VSBYS IN BR AT BOTH KRST/KLSE IN THE 09Z-1430Z
TIME-FRAME. THIS WILL HAVE TO BE WATCHED...IF HIGHER LEVEL CLOUDS
END UP MORE SCT OR THIN...ALLOWING FOR MORE RADIATIONAL COOLING...
FR VSBYS IN BR/FG COULD PREVAIL ACROSS THE AREA IN THE 09-14Z
PERIOD. SHRA/TSRA CHANCES LATER TONIGHT/THU TOO SMALL TO MENTION IN
TAFS FOR NOW.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1220 PM CDT WED AUG 28 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 334 AM CDT WED AUG 28 2013
..CURRENTLY AS OF 08Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED DEEP TROUGHING
JUST OFF THE U.S. WEST COAST WHILE STRONG SUBTROPICAL RIDGING
CONTINUES TO DOMINATE THE CENTRAL PLAINS. A WEAK RIDGE AXIS EXTENDED
FROM THE SUBTROPICAL RIDGE NORTH INTO THE DAKOTAS. MONSOONAL
MOISTURE AND SHORTWAVES CONTINUE TO ROTATE AROUND THE SUBTROPICAL
RIDGE...FROM ARIZONA INTO THE DAKOTAS AND SOUTHEAST THROUGH THE
FORECAST AREA. REGARDING THE MOISTURE...RAP PRECIPITABLE WATER
ANALYSIS SHOWED VALUES OF 1.5-2 INCHES EXTENDING FROM THE DAKOTAS
SOUTHEASTWARD THROUGH MUCH OF THE FORECAST AREA. EARLY THIS MORNING
ALL MONSOONAL SHORTWAVES WERE EITHER TO THE EAST OR WEST OF THE
FORECAST AREA...RESULTING IN DRY CONDITIONS. AT THE SURFACE A WEAK
COLD FRONT WAS SLOWLY DROPPING SOUTH THROUGH THE FORECAST AREA...NOW
STRETCHED ACROSS NORTHERN IOWA AND FAR SOUTHERN WI. THE FRONT HAS
HAD A HARD TIME SCOURING OUT THE SURFACE MOISTURE WITH DEWPOINTS
GENERALLY IN THE LOW 70S ACROSS THE AREA. THE COOLING WITH THE FRONT
HAS BEEN SHALLOW...EVIDENCED ON THE 00Z GRB SOUNDING WITH 925MB
TEMPS OF 22C COMPARED TO 29C AT DVN. SURFACE TEMPERATURES HAVE
FALLEN OFF INTO THE LOW TO MID 70S NORTH OF THE FRONT...AND MID TO
UPPER 70S TO THE SOUTH. THE COOLING INTERACTING WITH THE LINGERING
MOISTURE HAS CAUSED BOTH MIST AND LOW STRATUS TO FORM. VISIBILITIES
ARE LOWEST OVER NORTH CENTRAL WI DUE TO RECENT RAINS. 11-3.9 UM
IMAGERY SHOWED THE BULK OF THE STRATUS ACROSS CENTRAL AND EASTERN
WI.
..HAZARDS..
1. HEAT. NORTH OF I-90...HEAT INDICES ARE FORECAST BETWEEN
90-95...THEREFORE FEEL CONFIDENT NO ADDITIONAL HEAT ADVISORY IS
NEEDED. SOUTH OF I-90 HEAT INDICES ARE EXPECTED TO TOP OUT AROUND
95 TO AT MOST 100. GIVEN THAT THESE ARE BELOW ADVISORY CRITERIA
AND 5 TO 10 DEGREES LOWER THAN THE PAST FEW DAYS...HAVE DECLINED
TO ISSUE A HEAT ADVISORY HERE AS WELL.
2. DENSE FOG ACROSS TAYLOR AND CLARK COUNTIES...WHICH SHOULD
DISSIPATE BETWEEN 9-10 AM.
..SYNOPTIC OVERVIEW..
VERY LITTLE CHANGE IS FORECAST BY MODELS IN THE UPPER AIR PATTERN
DURING THE NEXT 24 HOURS. IF ANYTHING...THE WEAK RIDGE AXIS OVER THE
DAKOTAS GETS FLATTENED OUT AND PUSHED EAST...IN RESPONSE TO A
STRONGER MONSOONAL SHORTWAVE LIFTING INTO NORTH DAKOTA BY 12Z
THURSDAY. AT THE SURFACE...THE WEAK COLD FRONT OVER THE SOUTHERN
PORTION OF THE FORECAST AREA LOOKS TO CONTINUE TO SLOWLY DRIFT
SOUTH...PROGGED TO BISECT IOWA NORTHWEST TO SOUTHEAST BY 00Z. IN
ITS WAKE...HIGH PRESSURE BUILDS IN OVER WISCONSIN. THE FRONT MAY
START TO LIFT BACK TOWARDS THE AREA LATE TONIGHT IN RESPONSE TO WARM
ADVECTION AHEAD OF THE SHORTWAVE MOVING INTO NORTH DAKOTA.
..DETAILS..
SOLAR HEATING WILL HELP TO GRADUALLY IMPROVE VISIBILITIES AND MIX
OUT THE LOW STRATUS AIMING AT SOUTHWEST WI THIS MORNING. BY 18Z ALL
FOG AND STRATUS SHOULD BE GONE. OTHERWISE...DRY ADVECTION IN THE LOW
TO MID LEVELS OF THE ATMOSPHERE ACCOMPANYING THE SURFACE HIGH...
COMBINED WITH CAPPING BY A WARM LAYER AT 750MB...WILL HELP TO KEEP
CONDITIONS DRY TODAY. THE 28.00Z GFS DOES TRY TO CONVECT ACROSS
NORTHEAST IOWA NEAR THE FRONT THIS AFTERNOON...BUT IS THE ONLY MODEL
TO DO SO. HAVE KEPT THE FORECAST DRY DUE TO LIMITED CONVERGENCE ON
THE FRONT AND THE CAPPING POTENTIAL...ALONG WITH ALL OTHER MODELS
SUGGESTING DRY CONDITIONS ON THE FRONT. TEMPERATURES TODAY WILL BE
ABOUT 5 DEGREES COOLER WITH 925MB READINGS DOWN TO 24-26C VERSUS THE
28-30C THAT OCCURRED YESTERDAY. SURFACE DEWPOINTS...ON THE OTHER
HAND...ARE STILL GOING TO BE STUCK IN THE LOW TO PERHAPS MID 70S
SOUTH OF I-90. THUS HEAT INDICES IN THIS AREA OF 95 TO AT MOST 100
ARE EXPECTED. TO THE NORTH...DEWPOINTS SHOULD MIX/FALL INTO THE
60S...KEEPING HEAT INDICES MORE IN THE 90-95 RANGE.
FOR TONIGHT...GOOD MODEL AGREEMENT EXISTS ON THE WARM ADVECTION
SCENARIO. THE BIGGEST ISSUES ARE IF AND WHEN CONVECTION CAN FIRE
FROM THE WARM ADVECTION. HERE AGAIN...THE 28.00Z GFS IS QUICKEST AND
MOST EXPANSIVE...SUGGESTING CONVECTION WEST OF THE MS RIVER ALL
NIGHT. ALL OTHER GUIDANCE WAITS UNTIL AFTER MIDNIGHT...AND IN THE
CASE OF THE 28.00Z REGIONAL CANADIAN AS WELL AS THE 28.00Z NAM...
THEY NEVER FIRE ANY CONVECTION. FOR NOW HAVE LEANED MORE TOWARDS THE
CONSISTENT ECMWF AS IT ALSO HAS DONE BEST WITH CONVECTION AS OF
LATE. THE MODEL SUGGESTS ELEVATED CONVECTION FIRING AFTER MIDNIGHT
FROM GRAND FORKS DOWN TO AROUND AUSTIN. GIVEN THAT THIS CONVECTION
WILL OCCUR IN THE 1.5-2 INCH PRECIPITABLE WATER STREAM...LOCALLY
HEAVY RAIN COULD OCCUR WITH THE STORMS. ANOTHER MILD TO WARM NIGHT
EXPECTED AGAIN...WARMEST WEST OF THE MS RIVER WITH MORE CLOUDS AND
HIGHER DEWPOINTS.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 334 AM CDT WED AUG 28 2013
..HAZARDS..
1. HEAT. POTENTIAL FOR ANOTHER HEAT ADVISORY COME FRIDAY...
ESPECIALLY ACROSS NORTHEAST IOWA. SATURDAY ALSO HAS A POTENTIAL NEED
FOR A HEAT ADVISORY IF WARM AIR PROGGED THEN ADVECTS IN FASTER.
2. STORMS. THOSE STORMS THAT OCCUR THURSDAY NIGHT ALONG/NORTHEAST OF
I-94 COULD POSE A HEAVY RAIN CONCERN WITH A SMALL RISK OF DAMAGING
WINDS.
..SYNOPTIC OVERVIEW..
28.00Z MODEL GUIDANCE REMAINS IN GOOD AGREEMENT WITH YESTERDAYS
MODEL RUNS OF SHOWING THE SUBTROPICAL RIDGE RETROGRADING INTO THE
FOUR CORNERS REGION THIS WEEKEND. THIS RESULTS IN A GRADUAL FALL OF
500MB HEIGHTS OVER THE FORECAST AREA. ADDITIONALLY...THE BULK OF THE
DEEP TROUGH JUST OFF THE U.S. WEST COAST IS PROGGED TO EJECT OUT
ACROSS SOUTHERN CANADA THIS FRIDAY AND SATURDAY. MODELS HAVE
STRUGGLED A BIT ON THE DEGREE OF AMPLIFICATION WITH THIS TROUGH AS
IT APPROACHES NORTHERN ONTARIO AND LAKE SUPERIOR SUNDAY MORNING...
BUT THEY APPEAR NOW TO HAVE SETTLED DOWN. ALL INDICATIONS ARE THAT
AFTER IT PASSES LAKE SUPERIOR...THE TROUGH WILL THEN DIG INTO THE
EASTERN GREAT LAKES MONDAY AND TUESDAY...WHILE UPPER RIDGING BUILDS
BACK UP OVER THE NORTHERN PLAINS.
..DETAILS..
THE SHORTWAVE OVER NORTH DAKOTA AT 12Z THURSDAY LOOKS TO TRACK
ACROSS NORTHERN MN ON THURSDAY AND INTO UPPER MI THURSDAY NIGHT.
GIVEN THIS TRACK...THE BULK OF THE DYNAMIC FORCING WILL STAY NORTH
OF THE FORECAST AREA...THOUGH TAYLOR AND CLARK COUNTIES COULD GET
BRUSHED. MORE IMPORTANTLY ABOUT THIS SHORTWAVE IS THE ISENTROPIC
LIFT AND LOW LEVEL MOISTURE TRANSPORT OCCURRING WITH IT AND TO ITS
SOUTH. ON THURSDAY...THIS ISENTROPIC LIFT CENTERED ON THE 310-315K
SURFACES AND LOW LEVEL MOISTURE TRANSPORT SLOWLY MARCHES ACROSS THE
FORECAST AREA...GETTING HUNG UP ACROSS WISCONSIN AT 00Z FRIDAY. THE
STRONGEST LIFT/MOISTURE TRANSPORT IS SITUATED NORTH OF THE FORECAST
AREA...BUT STILL WARRANTS 20-40 PERCENT CHANCES. CHANCES INCREASE
ACROSS WISCONSIN THURSDAY NIGHT...ESPECIALLY ALONG/NORTHEAST OF
I-94...AS THE MOISTURE TRANSPORT INCREASES WITH THE NOCTURNAL
INCREASE OF THE LOW LEVEL JET. STRONG MODEL CONSENSUS FOR CONVECTION
THUS 60-70 PERCENT CHANCES SEEM REASONABLE. ALONG AND WEST OF THE MS
RIVER THURSDAY NIGHT...THERE MAY BE VERY LITTLE TO ANY ACTIVITY.
TEMPERATURES ON THURSDAY DEPEND ON HOW MUCH SUN WE SEE...AND WITH
925MB READINGS RANGING FROM 22C EAST TO 27C WEST...THERE COULD BE A
WIDE SPREAD IN HIGHS. FOLLOWED A GUIDANCE CONSENSUS FOR NOW
RESULTING HIGHS IN THE 80S...WARMEST WEST AND IN RIVER VALLEYS.
GUIDANCE CONSENSUS ALSO FOLLOWED FOR LOWS THURSDAY NIGHT.
FOR FRIDAY INTO FRIDAY NIGHT...MODELS CONTINUE TO SHOW A SECOND
SHORTWAVE DROPPING SOUTHEAST OUT OF CENTRAL MN THROUGH THE FORECAST
AREA ON FRIDAY. WITH THIS SHORTWAVE COMING THROUGH AT PEAK HEATING
AND PLENTY OF MOISTURE IN PLACE...NOTED BY PRECIPITABLE WATER VALUES
PROGGED BETWEEN 1.5-1.75 INCHES...NEED TO HAVE SOME CHANCES OF
SHOWERS AND THUNDERSTORMS. MODELS VARY A BIT ON THE STRENGTH OF THIS
SHORTWAVE THUS CHANCES ARE ONLY IN THE 20-30 RANGE. WE MIGHT BE ABLE
TO SQUEEZE IN FRIDAY NIGHT AS DRY PER 28.00Z ECMWF/NAM...HOWEVER...
THE 28.00Z GFS SHOWS WARM AIR ADVECTION RETURNING AHEAD OF A COLD
FRONT MARCHING ACROSS THE DAKOTAS. TO ACCOUNT FOR THE GFS
SCENARIO...HAVE KEPT 20-30 PERCENT CHANCES GOING. FRIDAY HIGHS ARE
ALSO TRICKY AS THEY DEPEND BOTH ON STRENGTH AND TIMING OF THE
SHORTWAVE. THE ECMWF/GFS/CANADIAN ALL SHOW AN INFLUX OF 28-30C 925MB
AIR INTO THE FORECAST AREA...WHICH COULD SUPPORT HIGHS IN THE MID
90S LIKE WE HAVE SEEN. BEST PROBABILITY OF THIS APPEARS TO BE IN
NORTHEAST IOWA WHICH THEN WOULD HAVE THE BEST CHANCE OF NEEDING A
HEAT ADVISORY. THE REST OF THE AREA IS A LITTLE MORE UNCERTAIN.
FOR SATURDAY AND BEYOND...
FOCUS IS ALL ON THAT TROUGH COMING ACROSS SOUTHERN CANADA. MODELS
ARE IN PRETTY GOOD AGREEMENT SHOWING THE COLD FRONT CROSSING THE
AREA DURING THE DAY SUNDAY. AHEAD OF THE FRONT...THERE WILL BE
ANOTHER SURGE OF WARM AIR COMING INTO THE AREA FOR SATURDAY. IF THE
GFS IS CORRECT WITH 925MB TEMPS OF 29-31C...A HEAT ADVISORY WOULD BE
REQUIRED...WHILE THE ECMWF IS MORE SCALED BACK WITH 925MB TEMPS OF
25-28C. FOR NOW THE HIGH TEMPERATURE FORECAST SPLITS THE DIFFERENCE
BETWEEN THESE MODELS. COULD SEE SOME WARM ADVECTION SHOWERS/STORMS
TOO...RIGHT THROUGH SATURDAY NIGHT. ADDITIONALLY...THERE COULD BE
SOME SHOWERS/STORMS THAT ARE FRONTOGENETICALLY DRIVEN AROUND THE
COLD FRONT ON SUNDAY. THEREFORE...20-40 PERCENT CHANCES PER
CONSENSUS ARE IN THE FORECAST. AFTER SUNDAY...DRY CONDITIONS WILL
PREVAIL AS HIGH PRESSURE BUILDS IN AND PERSISTS OVER THE AREA.
TEMPERATURES SUNDAY AND BEYOND ARE TRICKY AS THE 00Z AND 12Z ECMWF
RUNS ALTERNATE ON THE STRENGTH OF COLD ADVECTION. FOR NOW STUCK WITH
A MODEL CONSENSUS FOR HIGHS AND LOWS SUNDAY THROUGH TUESDAY...BUT IF
THE 00Z ECMWF RUNS ARE CORRECT...TEMPERATURES MAY NEED TO BE LOWERED
ANOTHER 5 DEGREES OR SO.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1220 PM CDT WED AUG 28 2013
EASTERLY WINDS IN THE SFC-850MB LAYER CONTINUE TO ADVECT MVFR
STRATUS DECKS WESTWARD ACROSS THE TAF SITES EARLY THIS AFTERNOON.
THESE CLOUDS/MOISTURE STUCK UNDER A MDT/STRONG INVERSION NEAR
900MB...MAKING THE CLOUDS MUCH MORE PERSISTENT THAN EARLIER THOUGHT.
WITH DIURNAL WARMING/MIXING...THE CLOUD DECK WILL SLOWLY BECOME
BKN-SCT THRU THE AFTERNOON. WITH A FRONTAL BOUNDARY JUST SOUTH OF
THE AREA AND THE MOISTURE TRAPPED UNDER THE INVERSION...SOME MVFR
CLOUDS LOOKING TO PERSIST WELL INTO TONIGHT AND LIKELY INTO THU.
DEBRIS CLOUDS FROM CONVECTION TO THE WEST TO SPREAD ACROSS THE AREA
TONIGHT. WITH THE HUMID LOW LEVEL AIRMASS AND GENERALLY LIGHT
WINDS...THESE HIGHER LEVEL CLOUDS SHOULD HELP KEEP FOG FROM BECOMING
WIDESPREAD AND DENSE LATE TONIGHT/EARLY THU MORNING. HOWEVER...
CONTINUED/ADDED MVFR VSBYS IN BR AT BOTH KRST/KLSE IN THE 09Z-1430Z
TIME-FRAME. THIS WILL HAVE TO BE WATCHED...IF HIGHER LEVEL CLOUDS
END UP MORE SCT OR THIN...ALLOWING FOR MORE RADIATIONAL COOLING...
FR VSBYS IN BR/FG COULD PREVAIL ACROSS THE AREA IN THE 09-14Z
PERIOD. SHRA/TSRA CHANCES LATER TONIGHT/THU TOO SMALL TO MENTION IN
TAFS FOR NOW.
&&
.CLIMATE...
ISSUED AT 334 AM CDT WED AUG 28 2013
THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER
INTO LABOR DAY WEEKEND...GIVEN STILL MORE HEAT FORECAST. FOR MORE
CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON
THE RECENT HEAT.
LA CROSSE ROCHESTER
--------- ---------
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM....AJ
AVIATION.....RRS
CLIMATE......AJ
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1210 PM CDT WED AUG 28 2013
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND THURSDAY
ISSUED AT 405 AM CDT WED AUG 28 2013
FORECAST CONCERNS ON CLOUDS AND FOG THIS MORNING. MODELS FAIRLY
SIMILAR WITH FRONT SOUTH OF CWA. NORTHEAST WINDS AT SFC AND ALOFT BEHIND
FRONT...HAS LED TO WIDESPREAD LOW CLOUDS OFF LAKES TO MOVE OVER
MUCH OF CWA. LESS CLOUDS OVER NORTH CENTRAL HAS LED TO WIDESPREAD
DENSE FOG WITH VISIBILITIES FLUCTUATING AROUND 1/4 MILE. WILL
COVER WITH ADVISORY THROUGH 8AM. GUIDANCE SUGGESTS LOW CLOUDS TO
STICK AROUND A BIT THIS MORNING...WITH RUC SOUNDINGS CARRYING IT
INTO MID/LATE MORNING. HAVE LOWERED MAX TEMPS A BIT TODAY DUE TO
MORNING CLOUDS.
NUMBER OF MODELS CONTINUE TO CARRY LIGHT QPF FAR EASTERN WI TODAY.
NOT SEEING MUCH SUPPORT BESIDES SOME WEAK SURFACE CONVERGENCE...
THOUGH WITH CONTINUED MOIST AIR MASS AND ASSOCIATED INSTABILITY
CANNOT TOTALLY RULE OUT. WILL STAY DRY AT THIS TIME AND ADVISE
NEXT SHIFT.
FRONT BEGINS TO LIFT NORTH TONIGHT WITH BEST DYNAMICS OVER ND/MN.
EXPECT MCS A GOOD POSSIBILITY ON NOSE OF LLVL JET AS SUGGESTED BY MODELS.
GIVEN THERMAL PATTERN AND CORFIDI VECTORS...COMPLEX TO MOVE EAST
AND SOUTHEAST. MODELS SUGGEST COMPLEX MOVING INTO NORTHERN CWA BY
AFTERNOON. HAVE EXPANDED POPS GIVEN SCENARIO.
TEMPERATURES TO CONTINUE TO RUN WARMER THAN NORMAL THIS
PERIOD...THOUGH COOLER THAN PREVIOUS FEW DAYS.
.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
ISSUED AT 405 AM CDT WED AUG 28 2013
ALTHOUGH THERE ARE SOME TIMING DIFFERENCES AMONG THE
MODELS...PRECIPITATION CHANCES SHOULD BE HIGHEST ON THURSDAY
NIGHT AS AN UPPER LEVEL SHORT WAVE TOPS THE RIDGE. THERE WILL ALSO
BE ASSISTANCE FROM SOME 300MB DIVERGENCE AND AN APPROACHING
SURFACE SYSTEM.
THUNDERSTORM CHANCES REMAIN FOR FRIDAY AND SATURDAY WITH WARM AND
HUMID AIR IN PLACE...BUT DO NOT REALLY SEE MUCH FORCING. A COLD
FRONT PUSHING THROUGH TO START NEXT WEEK WILL BRING A CHANCE OF
SHOWERS AND THUNDERSTORMS THROUGH SUNDAY...AND COOLER
TEMPERATURES FOR MONDAY AND TUESDAY.
HAVE GENERALLY USED A MIX OF GUIDANCE AND PREVIOUS FORECAST
TEMPERATURES FOR MAX AND MIN TEMPERATURES DURING THE PERIOD.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1205 PM CDT WED AUG 28 2013
MVFR CIGS CONTINUED ACROSS CENTRAL AND PORTIONS OF NORTHEAST
WISCONSIN EARLY THIS AFTERNOON. AN UNUSUAL FOG EVENT OCCURRED
AT THE KGRB TAF SITE THIS MORNING AS FOG ROLLED OFF THE BAY ON
NORTHEAST WINDS BETWEEN 9 AM AND 11 AM. MOST SITES WILL CLIMB INTO
THE VFR CATEGORY LATE THIS AFTERNOON. THE ONLY EXCEPTION WILL BE
NEAR LAKE MICHIGAN WHERE SOME MVFR/IFR CONDITIONS COULD CONTINUE
DUE TO FOG OFF THE LAKE.
MAIN CONCERN FOR TONIGHT WILL BE THE FOG AND STRATUS POTENTIAL.
THE COMBINATION OF LIGHT WINDS...PARTLY CLOUDY SKIES AND RELATIVELY
HIGH DEW POINTS WOULD SUGGEST THAT FOG...MORE THAN LIKELY DENSE IN
SPOTS CAN BE EXPECTED. INTRODUCED SOME LIGHT FOG AROUND 03Z IN THE
TAFS AND THEN HIT THE TAFS HARD BETWEEN 06Z-15Z. AGAIN...SOME SITES
MAY DROP BELOW AIRPORT MINIMUMS. ANY LOWS AND FOG SHOULD BURN OFF
BY 15-16Z. IT APPEARS THERE IS A SMALL CHANCE OF SHOWERS AND STORMS
ACROSS THE WEST AND FAR NORTHWEST AFTER 18Z ON THURSDAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......MG
AVIATION.......ECKBERG
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
910 AM CDT WED AUG 28 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 334 AM CDT WED AUG 28 2013
..CURRENTLY AS OF 08Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED DEEP TROUGHING
JUST OFF THE U.S. WEST COAST WHILE STRONG SUBTROPICAL RIDGING
CONTINUES TO DOMINATE THE CENTRAL PLAINS. A WEAK RIDGE AXIS EXTENDED
FROM THE SUBTROPICAL RIDGE NORTH INTO THE DAKOTAS. MONSOONAL
MOISTURE AND SHORTWAVES CONTINUE TO ROTATE AROUND THE SUBTROPICAL
RIDGE...FROM ARIZONA INTO THE DAKOTAS AND SOUTHEAST THROUGH THE
FORECAST AREA. REGARDING THE MOISTURE...RAP PRECIPITABLE WATER
ANALYSIS SHOWED VALUES OF 1.5-2 INCHES EXTENDING FROM THE DAKOTAS
SOUTHEASTWARD THROUGH MUCH OF THE FORECAST AREA. EARLY THIS MORNING
ALL MONSOONAL SHORTWAVES WERE EITHER TO THE EAST OR WEST OF THE
FORECAST AREA...RESULTING IN DRY CONDITIONS. AT THE SURFACE A WEAK
COLD FRONT WAS SLOWLY DROPPING SOUTH THROUGH THE FORECAST AREA...NOW
STRETCHED ACROSS NORTHERN IOWA AND FAR SOUTHERN WI. THE FRONT HAS
HAD A HARD TIME SCOURING OUT THE SURFACE MOISTURE WITH DEWPONTS
GENERALLY IN THE LOW 70S ACROSS THE AREA. THE COOLING WITH THE FRONT
HAS BEEN SHALLOW...EVIDENCED ON THE 00Z GRB SOUNDING WITH 925MB
TEMPS OF 22C COMPARED TO 29C AT DVN. SURFACE TEMPERATURES HAVE
FALLEN OFF INTO THE LOW TO MID 70S NORTH OF THE FRONT...AND MID TO
UPPER 70S TO THE SOUTH. THE COOLING INTERACTING WITH THE LINGERING
MOISTURE HAS CAUSED BOTH MIST AND LOW STRATUS TO FORM. VISIBILITIES
ARE LOWEST OVER NORTH CENTRAL WI DUE TO RECENT RAINS. 11-3.9 UM
IMAGERY SHOWED THE BULK OF THE STRATUS ACROSS CENTRAL AND EASTERN
WI.
..HAZARDS..
1. HEAT. NORTH OF I-90...HEAT INDICES ARE FORECAST BETWEEN
90-95...THEREFORE FEEL CONFIDENT NO ADDITIONAL HEAT ADVISORY IS
NEEDED. SOUTH OF I-90 HEAT INDICES ARE EXPECTED TO TOP OUT AROUND
95 TO AT MOST 100. GIVEN THAT THESE ARE BELOW ADVISORY CRITERIA
AND 5 TO 10 DEGREES LOWER THAN THE PAST FEW DAYS...HAVE DECLINED
TO ISSUE A HEAT ADVISORY HERE AS WELL.
2. DENSE FOG ACROSS TAYLOR AND CLARK COUNTIES...WHICH SHOULD
DISSIPATE BETWEEN 9-10 AM.
..SYNOPTIC OVERVIEW..
VERY LITTLE CHANGE IS FORECAST BY MODELS IN THE UPPER AIR PATTERN
DURING THE NEXT 24 HOURS. IF ANYTHING...THE WEAK RIDGE AXIS OVER THE
DAKOTAS GETS FLATTENED OUT AND PUSHED EAST...IN RESPONSE TO A
STRONGER MONSOONAL SHORTWAVE LIFTING INTO NORTH DAKOTA BY 12Z
THURSDAY. AT THE SURFACE...THE WEAK COLD FRONT OVER THE SOUTHERN
PORTION OF THE FORECAST AREA LOOKS TO CONTINUE TO SLOWLY DRIFT
SOUTH...PROGGED TO BISECT IOWA NORTHWEST TO SOUTHEAST BY 00Z. IN
ITS WAKE...HIGH PRESSURE BUILDS IN OVER WISCONSIN. THE FRONT MAY
START TO LIFT BACK TOWARDS THE AREA LATE TONIGHT IN RESPONSE TO WARM
ADVECTION AHEAD OF THE SHORTWAVE MOVING INTO NORTH DAKOTA.
..DETAILS..
SOLAR HEATING WILL HELP TO GRADUALLY IMPROVE VISIBILITIES AND MIX
OUT THE LOW STRATUS AIMING AT SOUTHWEST WI THIS MORNING. BY 18Z ALL
FOG AND STRATUS SHOULD BE GONE. OTHERWISE...DRY ADVECTION IN THE LOW
TO MID LEVELS OF THE ATMOSPHERE ACCOMPANYING THE SURFACE HIGH...
COMBINED WITH CAPPING BY A WARM LAYER AT 750MB...WILL HELP TO KEEP
CONDITIONS DRY TODAY. THE 28.00Z GFS DOES TRY TO CONVECT ACROSS
NORTHEAST IOWA NEAR THE FRONT THIS AFTERNOON...BUT IS THE ONLY MODEL
TO DO SO. HAVE KEPT THE FORECAST DRY DUE TO LIMITED CONVERGENCE ON
THE FRONT AND THE CAPPING POTENTIAL...ALONG WITH ALL OTHER MODELS
SUGGESTING DRY CONDITIONS ON THE FRONT. TEMPERATURES TODAY WILL BE
ABOUT 5 DEGREES COOLER WITH 925MB READINGS DOWN TO 24-26C VERSUS THE
28-30C THAT OCCURRED YESTERDAY. SURFACE DEWPOINTS...ON THE OTHER
HAND...ARE STILL GOING TO BE STUCK IN THE LOW TO PERHAPS MID 70S
SOUTH OF I-90. THUS HEAT INDICES IN THIS AREA OF 95 TO AT MOST 100
ARE EXPECTED. TO THE NORTH...DEWPOINTS SHOULD MIX/FALL INTO THE
60S...KEEPING HEAT INDICES MORE IN THE 90-95 RANGE.
FOR TONIGHT...GOOD MODEL AGREEMENT EXISTS ON THE WARM ADVECTION
SCENARIO. THE BIGGEST ISSUES ARE IF AND WHEN CONVECTION CAN FIRE
FROM THE WARM ADVECTION. HERE AGAIN...THE 28.00Z GFS IS QUICKEST AND
MOST EXPANSIVE...SUGGESTING CONVECTION WEST OF THE MS RIVER ALL
NIGHT. ALL OTHER GUIDANCE WAITS UNTIL AFTER MIDNIGHT...AND IN THE
CASE OF THE 28.00Z REGIONAL CANADIAN AS WELL AS THE 28.00Z NAM...
THEY NEVER FIRE ANY CONVECTION. FOR NOW HAVE LEANED MORE TOWARDS THE
CONSISTENT ECMWF AS IT ALSO HAS DONE BEST WITH CONVECTION AS OF
LATE. THE MODEL SUGGESTS ELEVATED CONVECTION FIRING AFTER MIDNIGHT
FROM GRAND FORKS DOWN TO AROUND AUSTIN. GIVEN THAT THIS CONVECTION
WILL OCCUR IN THE 1.5-2 INCH PRECIPITABLE WATER STREAM...LOCALLY
HEAVY RAIN COULD OCCUR WITH THE STORMS. ANOTHER MILD TO WARM NIGHT
EXPECTED AGAIN...WARMEST WEST OF THE MS RIVER WITH MORE CLOUDS AND
HIGHER DEWPOINTS.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 334 AM CDT WED AUG 28 2013
..HAZARDS..
1. HEAT. POTENTIAL FOR ANOTHER HEAT ADVISORY COME FRIDAY...
ESPECIALLY ACROSS NORTHEAST IOWA. SATURDAY ALSO HAS A POTENTIAL NEED
FOR A HEAT ADVISORY IF WARM AIR PROGGED THEN ADVECTS IN FASTER.
2. STORMS. THOSE STORMS THAT OCCUR THURSDAY NIGHT ALONG/NORTHEAST OF
I-94 COULD POSE A HEAVY RAIN CONCERN WITH A SMALL RISK OF DAMAGING
WINDS.
..SYNOPTIC OVERVIEW..
28.00Z MODEL GUIDANCE REMAINS IN GOOD AGREEMENT WITH YESTERDAYS
MODEL RUNS OF SHOWING THE SUBTROPICAL RIDGE RETROGRADING INTO THE
FOUR CORNERS REGION THIS WEEKEND. THIS RESULTS IN A GRADUAL FALL OF
500MB HEIGHTS OVER THE FORECAST AREA. ADDITIONALLY...THE BULK OF THE
DEEP TROUGH JUST OFF THE U.S. WEST COAST IS PROGGED TO EJECT OUT
ACROSS SOUTHERN CANADA THIS FRIDAY AND SATURDAY. MODELS HAVE
STRUGGLED A BIT ON THE DEGREE OF AMPLIFICATION WITH THIS TROUGH AS
IT APPROACHES NORTHERN ONTARIO AND LAKE SUPERIOR SUNDAY MORNING...
BUT THEY APPEAR NOW TO HAVE SETTLED DOWN. ALL INDICATIONS ARE THAT
AFTER IT PASSES LAKE SUPERIOR...THE TROUGH WILL THEN DIG INTO THE
EASTERN GREAT LAKES MONDAY AND TUESDAY...WHILE UPPER RIDGING BUILDS
BACK UP OVER THE NORTHERN PLAINS.
..DETAILS..
THE SHORTWAVE OVER NORTH DAKOTA AT 12Z THURSDAY LOOKS TO TRACK
ACROSS NORTHERN MN ON THURSDAY AND INTO UPPER MI THURSDAY NIGHT.
GIVEN THIS TRACK...THE BULK OF THE DYNAMIC FORCING WILL STAY NORTH
OF THE FORECAST AREA...THOUGH TAYLOR AND CLARK COUNTIES COULD GET
BRUSHED. MORE IMPORTANTLY ABOUT THIS SHORTWAVE IS THE ISENTROPIC
LIFT AND LOW LEVEL MOISTURE TRANSPORT OCCURRING WITH IT AND TO ITS
SOUTH. ON THURSDAY...THIS ISENTROPIC LIFT CENTERED ON THE 310-315K
SURFACES AND LOW LEVEL MOISTURE TRANSPORT SLOWLY MARCHES ACROSS THE
FORECAST AREA...GETTING HUNG UP ACROSS WISCONSIN AT 00Z FRIDAY. THE
STRONGEST LIFT/MOISTURE TRANSPORT IS SITUATED NORTH OF THE FORECAST
AREA...BUT STILL WARRANTS 20-40 PERCENT CHANCES. CHANCES INCREASE
ACROSS WISCONSIN THURSDAY NIGHT...ESPECIALLY ALONG/NORTHEAST OF
I-94...AS THE MOISTURE TRANSPORT INCREASES WITH THE NOCTURNAL
INCREASE OF THE LOW LEVEL JET. STRONG MODEL CONSENSUS FOR CONVECTION
THUS 60-70 PERCENT CHANCES SEEM REASONABLE. ALONG AND WEST OF THE MS
RIVER THURSDAY NIGHT...THERE MAY BE VERY LITTLE TO ANY ACTIVITY.
TEMPERATURES ON THURSDAY DEPEND ON HOW MUCH SUN WE SEE...AND WITH
925MB READINGS RANGING FROM 22C EAST TO 27C WEST...THERE COULD BE A
WIDE SPREAD IN HIGHS. FOLLOWED A GUIDANCE CONSENSUS FOR NOW
RESULTING HIGHS IN THE 80S...WARMEST WEST AND IN RIVER VALLEYS.
GUIDANCE CONSENSUS ALSO FOLLOWED FOR LOWS THURSDAY NIGHT.
FOR FRIDAY INTO FRIDAY NIGHT...MODELS CONTINUE TO SHOW A SECOND
SHORTWAVE DROPPING SOUTHEAST OUT OF CENTRAL MN THROUGH THE FORECAST
AREA ON FRIDAY. WITH THIS SHORTWAVE COMING THROUGH AT PEAK HEATING
AND PLENTY OF MOISTURE IN PLACE...NOTED BY PRECIPITABLE WATER VALUES
PROGGED BETWEEN 1.5-1.75 INCHES...NEED TO HAVE SOME CHANCES OF
SHOWERS AND THUNDERSTORMS. MODELS VARY A BIT ON THE STRENGTH OF THIS
SHORTWAVE THUS CHANCES ARE ONLY IN THE 20-30 RANGE. WE MIGHT BE ABLE
TO SQUEEZE IN FRIDAY NIGHT AS DRY PER 28.00Z ECMWF/NAM...HOWEVER...
THE 28.00Z GFS SHOWS WARM AIR ADVECTION RETURNING AHEAD OF A COLD
FRONT MARCHING ACROSS THE DAKOTAS. TO ACCOUNT FOR THE GFS
SCENARIO...HAVE KEPT 20-30 PERCENT CHANCES GOING. FRIDAY HIGHS ARE
ALSO TRICKY AS THEY DEPEND BOTH ON STRENGTH AND TIMING OF THE
SHORTWAVE. THE ECMWF/GFS/CANADIAN ALL SHOW AN INFLUX OF 28-30C 925MB
AIR INTO THE FORECAST AREA...WHICH COULD SUPPORT HIGHS IN THE MID
90S LIKE WE HAVE SEEN. BEST PROBABILITY OF THIS APPEARS TO BE IN
NORTHEAST IOWA WHICH THEN WOULD HAVE THE BEST CHANCE OF NEEDING A
HEAT ADVISORY. THE REST OF THE AREA IS A LITTLE MORE UNCERTAIN.
FOR SATURDAY AND BEYOND...
FOCUS IS ALL ON THAT TROUGH COMING ACROSS SOUTHERN CANADA. MODELS
ARE IN PRETTY GOOD AGREEMENT SHOWING THE COLD FRONT CROSSING THE
AREA DURING THE DAY SUNDAY. AHEAD OF THE FRONT...THERE WILL BE
ANOTHER SURGE OF WARM AIR COMING INTO THE AREA FOR SATURDAY. IF THE
GFS IS CORRECT WITH 925MB TEMPS OF 29-31C...A HEAT ADVISORY WOULD BE
REQUIRED...WHILE THE ECMWF IS MORE SCALED BACK WITH 925MB TEMPS OF
25-28C. FOR NOW THE HIGH TEMPERATURE FORECAST SPLITS THE DIFFERENCE
BETWEEN THESE MODELS. COULD SEE SOME WARM ADVECTION SHOWERS/STORMS
TOO...RIGHT THROUGH SATURDAY NIGHT. ADDITIONALLY...THERE COULD BE
SOME SHOWERS/STORMS THAT ARE FRONTOGENETICALLY DRIVEN AROUND THE
COLD FRONT ON SUNDAY. THEREFORE...20-40 PERCENT CHANCES PER
CONSENSUS ARE IN THE FORECAST. AFTER SUNDAY...DRY CONDITIONS WILL
PREVAIL AS HIGH PRESSURE BUILDS IN AND PERSISTS OVER THE AREA.
TEMPERATURES SUNDAY AND BEYOND ARE TRICKY AS THE 00Z AND 12Z ECMWF
RUNS ALTERNATE ON THE STRENGTH OF COLD ADVECTION. FOR NOW STUCK WITH
A MODEL CONSENSUS FOR HIGHS AND LOWS SUNDAY THROUGH TUESDAY...BUT IF
THE 00Z ECMWF RUNS ARE CORRECT...TEMPERATURES MAY NEED TO BE LOWERED
ANOTHER 5 DEGREES OR SO.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 700 AM CDT WED AUG 28 2013
925 MB WINDS HAVE BROUGHT IN AN IFR DECK OF CLOUDS INTO CENTRAL
AND NORTH CENTRAL WISCONSIN. THESE CLOUDS HAVE FINALLY MADE THERE
WAY INTO KLSE. RAP SUGGESTS THAT THESE CLOUDS WILL GRADUALLY MOVE
SOUTH AND DISSIPATE BY 28.16Z.
MEANWHILE AT KRST...WATCHING A THUNDERSTORM COMPLEX OVER EASTERN
SOUTH DAKOTA. THE HRRR SHOWS THAT THIS SYSTEM WILL MOVE EAST
ACROSS MINNESOTA AND THEN DISSIPATE AS THE LOW LEVEL JET WEAKENS.
AS A RESULT...ONLY EXPECTING SOME 10-15K DECK OF CLOUDS TO MOVE
INTO KRST BY MID MORNING AND THEN LINGER THROUGH THE AFTERNOON.
FOR LATE TONIGHT...THE MODELS ARE SHOWING MODERATE 900-800 MB
FRONTOGENESIS WILL DEVELOP ACROSS SOUTHEAST MINNESOTA AND
NORTHEAST IOWA. THIS IS IN RESPONSE TO THE FRONT OVER NORTHERN
IOWA BEGINNING TO MOVE BACK TO THE NORTH AS A WARM FRONT. THIS WILL
RESULT IN THE DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS THE AREA. HOWEVER WAS RATHER UNCERTAIN ON WHETHER THEY
WOULD AFFECT KRST OR NOT...SO LEFT THEM OUT FOR NOW.
&&
.CLIMATE...
ISSUED AT 334 AM CDT WED AUG 28 2013
THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER
INTO LABOR DAY WEEKEND...GIVEN STILL MORE HEAT FORECAST. FOR MORE
CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON
THE RECENT HEAT.
LA CROSSE ROCHESTER
--------- ---------
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
CLIMATE...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
702 AM CDT WED AUG 28 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 334 AM CDT WED AUG 28 2013
..CURRENTLY AS OF 08Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED DEEP TROUGHING
JUST OFF THE U.S. WEST COAST WHILE STRONG SUBTROPICAL RIDGING
CONTINUES TO DOMINATE THE CENTRAL PLAINS. A WEAK RIDGE AXIS EXTENDED
FROM THE SUBTROPICAL RIDGE NORTH INTO THE DAKOTAS. MONSOONAL
MOISTURE AND SHORTWAVES CONTINUE TO ROTATE AROUND THE SUBTROPICAL
RIDGE...FROM ARIZONA INTO THE DAKOTAS AND SOUTHEAST THROUGH THE
FORECAST AREA. REGARDING THE MOISTURE...RAP PRECIPITABLE WATER
ANALYSIS SHOWED VALUES OF 1.5-2 INCHES EXTENDING FROM THE DAKOTAS
SOUTHEASTWARD THROUGH MUCH OF THE FORECAST AREA. EARLY THIS MORNING
ALL MONSOONAL SHORTWAVES WERE EITHER TO THE EAST OR WEST OF THE
FORECAST AREA...RESULTING IN DRY CONDITIONS. AT THE SURFACE A WEAK
COLD FRONT WAS SLOWLY DROPPING SOUTH THROUGH THE FORECAST AREA...NOW
STRETCHED ACROSS NORTHERN IOWA AND FAR SOUTHERN WI. THE FRONT HAS
HAD A HARD TIME SCOURING OUT THE SURFACE MOISTURE WITH DEWPONTS
GENERALLY IN THE LOW 70S ACROSS THE AREA. THE COOLING WITH THE FRONT
HAS BEEN SHALLOW...EVIDENCED ON THE 00Z GRB SOUNDING WITH 925MB
TEMPS OF 22C COMPARED TO 29C AT DVN. SURFACE TEMPERATURES HAVE
FALLEN OFF INTO THE LOW TO MID 70S NORTH OF THE FRONT...AND MID TO
UPPER 70S TO THE SOUTH. THE COOLING INTERACTING WITH THE LINGERING
MOISTURE HAS CAUSED BOTH MIST AND LOW STRATUS TO FORM. VISIBILITIES
ARE LOWEST OVER NORTH CENTRAL WI DUE TO RECENT RAINS. 11-3.9 UM
IMAGERY SHOWED THE BULK OF THE STRATUS ACROSS CENTRAL AND EASTERN
WI.
..HAZARDS..
1. HEAT. NORTH OF I-90...HEAT INDICES ARE FORECAST BETWEEN
90-95...THEREFORE FEEL CONFIDENT NO ADDITIONAL HEAT ADVISORY IS
NEEDED. SOUTH OF I-90 HEAT INDICES ARE EXPECTED TO TOP OUT AROUND
95 TO AT MOST 100. GIVEN THAT THESE ARE BELOW ADVISORY CRITERIA
AND 5 TO 10 DEGREES LOWER THAN THE PAST FEW DAYS...HAVE DECLINED
TO ISSUE A HEAT ADVISORY HERE AS WELL.
2. DENSE FOG ACROSS TAYLOR AND CLARK COUNTIES...WHICH SHOULD
DISSIPATE BETWEEN 9-10 AM.
..SYNOPTIC OVERVIEW..
VERY LITTLE CHANGE IS FORECAST BY MODELS IN THE UPPER AIR PATTERN
DURING THE NEXT 24 HOURS. IF ANYTHING...THE WEAK RIDGE AXIS OVER THE
DAKOTAS GETS FLATTENED OUT AND PUSHED EAST...IN RESPONSE TO A
STRONGER MONSOONAL SHORTWAVE LIFTING INTO NORTH DAKOTA BY 12Z
THURSDAY. AT THE SURFACE...THE WEAK COLD FRONT OVER THE SOUTHERN
PORTION OF THE FORECAST AREA LOOKS TO CONTINUE TO SLOWLY DRIFT
SOUTH...PROGGED TO BISECT IOWA NORTHWEST TO SOUTHEAST BY 00Z. IN
ITS WAKE...HIGH PRESSURE BUILDS IN OVER WISCONSIN. THE FRONT MAY
START TO LIFT BACK TOWARDS THE AREA LATE TONIGHT IN RESPONSE TO WARM
ADVECTION AHEAD OF THE SHORTWAVE MOVING INTO NORTH DAKOTA.
..DETAILS..
SOLAR HEATING WILL HELP TO GRADUALLY IMPROVE VISIBILITIES AND MIX
OUT THE LOW STRATUS AIMING AT SOUTHWEST WI THIS MORNING. BY 18Z ALL
FOG AND STRATUS SHOULD BE GONE. OTHERWISE...DRY ADVECTION IN THE LOW
TO MID LEVELS OF THE ATMOSPHERE ACCOMPANYING THE SURFACE HIGH...
COMBINED WITH CAPPING BY A WARM LAYER AT 750MB...WILL HELP TO KEEP
CONDITIONS DRY TODAY. THE 28.00Z GFS DOES TRY TO CONVECT ACROSS
NORTHEAST IOWA NEAR THE FRONT THIS AFTERNOON...BUT IS THE ONLY MODEL
TO DO SO. HAVE KEPT THE FORECAST DRY DUE TO LIMITED CONVERGENCE ON
THE FRONT AND THE CAPPING POTENTIAL...ALONG WITH ALL OTHER MODELS
SUGGESTING DRY CONDITIONS ON THE FRONT. TEMPERATURES TODAY WILL BE
ABOUT 5 DEGREES COOLER WITH 925MB READINGS DOWN TO 24-26C VERSUS THE
28-30C THAT OCCURRED YESTERDAY. SURFACE DEWPOINTS...ON THE OTHER
HAND...ARE STILL GOING TO BE STUCK IN THE LOW TO PERHAPS MID 70S
SOUTH OF I-90. THUS HEAT INDICES IN THIS AREA OF 95 TO AT MOST 100
ARE EXPECTED. TO THE NORTH...DEWPOINTS SHOULD MIX/FALL INTO THE
60S...KEEPING HEAT INDICES MORE IN THE 90-95 RANGE.
FOR TONIGHT...GOOD MODEL AGREEMENT EXISTS ON THE WARM ADVECTION
SCENARIO. THE BIGGEST ISSUES ARE IF AND WHEN CONVECTION CAN FIRE
FROM THE WARM ADVECTION. HERE AGAIN...THE 28.00Z GFS IS QUICKEST AND
MOST EXPANSIVE...SUGGESTING CONVECTION WEST OF THE MS RIVER ALL
NIGHT. ALL OTHER GUIDANCE WAITS UNTIL AFTER MIDNIGHT...AND IN THE
CASE OF THE 28.00Z REGIONAL CANADIAN AS WELL AS THE 28.00Z NAM...
THEY NEVER FIRE ANY CONVECTION. FOR NOW HAVE LEANED MORE TOWARDS THE
CONSISTENT ECMWF AS IT ALSO HAS DONE BEST WITH CONVECTION AS OF
LATE. THE MODEL SUGGESTS ELEVATED CONVECTION FIRING AFTER MIDNIGHT
FROM GRAND FORKS DOWN TO AROUND AUSTIN. GIVEN THAT THIS CONVECTION
WILL OCCUR IN THE 1.5-2 INCH PRECIPITABLE WATER STREAM...LOCALLY
HEAVY RAIN COULD OCCUR WITH THE STORMS. ANOTHER MILD TO WARM NIGHT
EXPECTED AGAIN...WARMEST WEST OF THE MS RIVER WITH MORE CLOUDS AND
HIGHER DEWPOINTS.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 334 AM CDT WED AUG 28 2013
..HAZARDS..
1. HEAT. POTENTIAL FOR ANOTHER HEAT ADVISORY COME FRIDAY...
ESPECIALLY ACROSS NORTHEAST IOWA. SATURDAY ALSO HAS A POTENTIAL NEED
FOR A HEAT ADVISORY IF WARM AIR PROGGED THEN ADVECTS IN FASTER.
2. STORMS. THOSE STORMS THAT OCCUR THURSDAY NIGHT ALONG/NORTHEAST OF
I-94 COULD POSE A HEAVY RAIN CONCERN WITH A SMALL RISK OF DAMAGING
WINDS.
..SYNOPTIC OVERVIEW..
28.00Z MODEL GUIDANCE REMAINS IN GOOD AGREEMENT WITH YESTERDAYS
MODEL RUNS OF SHOWING THE SUBTROPICAL RIDGE RETROGRADING INTO THE
FOUR CORNERS REGION THIS WEEKEND. THIS RESULTS IN A GRADUAL FALL OF
500MB HEIGHTS OVER THE FORECAST AREA. ADDITIONALLY...THE BULK OF THE
DEEP TROUGH JUST OFF THE U.S. WEST COAST IS PROGGED TO EJECT OUT
ACROSS SOUTHERN CANADA THIS FRIDAY AND SATURDAY. MODELS HAVE
STRUGGLED A BIT ON THE DEGREE OF AMPLIFICATION WITH THIS TROUGH AS
IT APPROACHES NORTHERN ONTARIO AND LAKE SUPERIOR SUNDAY MORNING...
BUT THEY APPEAR NOW TO HAVE SETTLED DOWN. ALL INDICATIONS ARE THAT
AFTER IT PASSES LAKE SUPERIOR...THE TROUGH WILL THEN DIG INTO THE
EASTERN GREAT LAKES MONDAY AND TUESDAY...WHILE UPPER RIDGING BUILDS
BACK UP OVER THE NORTHERN PLAINS.
..DETAILS..
THE SHORTWAVE OVER NORTH DAKOTA AT 12Z THURSDAY LOOKS TO TRACK
ACROSS NORTHERN MN ON THURSDAY AND INTO UPPER MI THURSDAY NIGHT.
GIVEN THIS TRACK...THE BULK OF THE DYNAMIC FORCING WILL STAY NORTH
OF THE FORECAST AREA...THOUGH TAYLOR AND CLARK COUNTIES COULD GET
BRUSHED. MORE IMPORTANTLY ABOUT THIS SHORTWAVE IS THE ISENTROPIC
LIFT AND LOW LEVEL MOISTURE TRANSPORT OCCURRING WITH IT AND TO ITS
SOUTH. ON THURSDAY...THIS ISENTROPIC LIFT CENTERED ON THE 310-315K
SURFACES AND LOW LEVEL MOISTURE TRANSPORT SLOWLY MARCHES ACROSS THE
FORECAST AREA...GETTING HUNG UP ACROSS WISCONSIN AT 00Z FRIDAY. THE
STRONGEST LIFT/MOISTURE TRANSPORT IS SITUATED NORTH OF THE FORECAST
AREA...BUT STILL WARRANTS 20-40 PERCENT CHANCES. CHANCES INCREASE
ACROSS WISCONSIN THURSDAY NIGHT...ESPECIALLY ALONG/NORTHEAST OF
I-94...AS THE MOISTURE TRANSPORT INCREASES WITH THE NOCTURNAL
INCREASE OF THE LOW LEVEL JET. STRONG MODEL CONSENSUS FOR CONVECTION
THUS 60-70 PERCENT CHANCES SEEM REASONABLE. ALONG AND WEST OF THE MS
RIVER THURSDAY NIGHT...THERE MAY BE VERY LITTLE TO ANY ACTIVITY.
TEMPERATURES ON THURSDAY DEPEND ON HOW MUCH SUN WE SEE...AND WITH
925MB READINGS RANGING FROM 22C EAST TO 27C WEST...THERE COULD BE A
WIDE SPREAD IN HIGHS. FOLLOWED A GUIDANCE CONSENSUS FOR NOW
RESULTING HIGHS IN THE 80S...WARMEST WEST AND IN RIVER VALLEYS.
GUIDANCE CONSENSUS ALSO FOLLOWED FOR LOWS THURSDAY NIGHT.
FOR FRIDAY INTO FRIDAY NIGHT...MODELS CONTINUE TO SHOW A SECOND
SHORTWAVE DROPPING SOUTHEAST OUT OF CENTRAL MN THROUGH THE FORECAST
AREA ON FRIDAY. WITH THIS SHORTWAVE COMING THROUGH AT PEAK HEATING
AND PLENTY OF MOISTURE IN PLACE...NOTED BY PRECIPITABLE WATER VALUES
PROGGED BETWEEN 1.5-1.75 INCHES...NEED TO HAVE SOME CHANCES OF
SHOWERS AND THUNDERSTORMS. MODELS VARY A BIT ON THE STRENGTH OF THIS
SHORTWAVE THUS CHANCES ARE ONLY IN THE 20-30 RANGE. WE MIGHT BE ABLE
TO SQUEEZE IN FRIDAY NIGHT AS DRY PER 28.00Z ECMWF/NAM...HOWEVER...
THE 28.00Z GFS SHOWS WARM AIR ADVECTION RETURNING AHEAD OF A COLD
FRONT MARCHING ACROSS THE DAKOTAS. TO ACCOUNT FOR THE GFS
SCENARIO...HAVE KEPT 20-30 PERCENT CHANCES GOING. FRIDAY HIGHS ARE
ALSO TRICKY AS THEY DEPEND BOTH ON STRENGTH AND TIMING OF THE
SHORTWAVE. THE ECMWF/GFS/CANADIAN ALL SHOW AN INFLUX OF 28-30C 925MB
AIR INTO THE FORECAST AREA...WHICH COULD SUPPORT HIGHS IN THE MID
90S LIKE WE HAVE SEEN. BEST PROBABILITY OF THIS APPEARS TO BE IN
NORTHEAST IOWA WHICH THEN WOULD HAVE THE BEST CHANCE OF NEEDING A
HEAT ADVISORY. THE REST OF THE AREA IS A LITTLE MORE UNCERTAIN.
FOR SATURDAY AND BEYOND...
FOCUS IS ALL ON THAT TROUGH COMING ACROSS SOUTHERN CANADA. MODELS
ARE IN PRETTY GOOD AGREEMENT SHOWING THE COLD FRONT CROSSING THE
AREA DURING THE DAY SUNDAY. AHEAD OF THE FRONT...THERE WILL BE
ANOTHER SURGE OF WARM AIR COMING INTO THE AREA FOR SATURDAY. IF THE
GFS IS CORRECT WITH 925MB TEMPS OF 29-31C...A HEAT ADVISORY WOULD BE
REQUIRED...WHILE THE ECMWF IS MORE SCALED BACK WITH 925MB TEMPS OF
25-28C. FOR NOW THE HIGH TEMPERATURE FORECAST SPLITS THE DIFFERENCE
BETWEEN THESE MODELS. COULD SEE SOME WARM ADVECTION SHOWERS/STORMS
TOO...RIGHT THROUGH SATURDAY NIGHT. ADDITIONALLY...THERE COULD BE
SOME SHOWERS/STORMS THAT ARE FRONTOGENETICALLY DRIVEN AROUND THE
COLD FRONT ON SUNDAY. THEREFORE...20-40 PERCENT CHANCES PER
CONSENSUS ARE IN THE FORECAST. AFTER SUNDAY...DRY CONDITIONS WILL
PREVAIL AS HIGH PRESSURE BUILDS IN AND PERSISTS OVER THE AREA.
TEMPERATURES SUNDAY AND BEYOND ARE TRICKY AS THE 00Z AND 12Z ECMWF
RUNS ALTERNATE ON THE STRENGTH OF COLD ADVECTION. FOR NOW STUCK WITH
A MODEL CONSENSUS FOR HIGHS AND LOWS SUNDAY THROUGH TUESDAY...BUT IF
THE 00Z ECMWF RUNS ARE CORRECT...TEMPERATURES MAY NEED TO BE LOWERED
ANOTHER 5 DEGREES OR SO.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 700 AM CDT WED AUG 28 2013
925 MB WINDS HAVE BROUGHT IN AN IFR DECK OF CLOUDS INTO CENTRAL
AND NORTH CENTRAL WISCONSIN. THESE CLOUDS HAVE FINALLY MADE THERE
WAY INTO KLSE. RAP SUGGESTS THAT THESE CLOUDS WILL GRADUALLY MOVE
SOUTH AND DISSIPATE BY 28.16Z.
MEANWHILE AT KRST...WATCHING A THUNDERSTORM COMPLEX OVER EASTERN
SOUTH DAKOTA. THE HRRR SHOWS THAT THIS SYSTEM WILL MOVE EAST
ACROSS MINNESOTA AND THEN DISSIPATE AS THE LOW LEVEL JET WEAKENS.
AS A RESULT...ONLY EXPECTING SOME 10-15K DECK OF CLOUDS TO MOVE
INTO KRST BY MID MORNING AND THEN LINGER THROUGH THE AFTERNOON.
FOR LATE TONIGHT...THE MODELS ARE SHOWING MODERATE 900-800 MB
FRONTOGENESIS WILL DEVELOP ACROSS SOUTHEAST MINNESOTA AND
NORTHEAST IOWA. THIS IS IN RESPONSE TO THE FRONT OVER NORTHERN
IOWA BEGINNING TO MOVE BACK TO THE NORTH AS A WARM FRONT. THIS WILL
RESULT IN THE DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS THE AREA. HOWEVER WAS RATHER UNCERTAIN ON WHETHER THEY
WOULD AFFECT KRST OR NOT...SO LEFT THEM OUT FOR NOW.
&&
.CLIMATE...
ISSUED AT 334 AM CDT WED AUG 28 2013
THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER
INTO LABOR DAY WEEKEND...GIVEN STILL MORE HEAT FORECAST. FOR MORE
CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON
THE RECENT HEAT.
LA CROSSE ROCHESTER
--------- ---------
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR WIZ017-029.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
CLIMATE...AJ
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
642 AM CDT WED AUG 28 2013
UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND THURSDAY
ISSUED AT 405 AM CDT WED AUG 28 2013
FORECAST CONCERNS ON CLOUDS AND FOG THIS MORNING. MODELS FAIRLY
SIMILAR WITH FRONT SOUTH OF CWA. NORTHEAST WINDS AT SFC AND ALOFT BEHIND
FRONT...HAS LED TO WIDESPREAD LOW CLOUDS OFF LAKES TO MOVE OVER
MUCH OF CWA. LESS CLOUDS OVER NORTH CENTRAL HAS LED TO WIDESPREAD
DENSE FOG WITH VISIBILITIES FLUCTUATING AROUND 1/4 MILE. WILL
COVER WITH ADVISORY THROUGH 8AM. GUIDANCE SUGGESTS LOW CLOUDS TO
STICK AROUND A BIT THIS MORNING...WITH RUC SOUNDINGS CARRYING IT
INTO MID/LATE MORNING. HAVE LOWERED MAX TEMPS A BIT TODAY DUE TO
MORNING CLOUDS.
NUMBER OF MODELS CONTINUE TO CARRY LIGHT QPF FAR EASTERN WI TODAY.
NOT SEEING MUCH SUPPORT BESIDES SOME WEAK SURFACE CONVERGENCE...
THOUGH WITH CONTINUED MOIST AIR MASS AND ASSOCIATED INSTABILITY
CANNOT TOTALLY RULE OUT. WILL STAY DRY AT THIS TIME AND ADVISE
NEXT SHIFT.
FRONT BEGINS TO LIFT NORTH TONIGHT WITH BEST DYNAMICS OVER ND/MN.
EXPECT MCS A GOOD POSSIBILITY ON NOSE OF LLVL JET AS SUGGESTED BY MODELS.
GIVEN THERMAL PATTERN AND CORFIDI VECTORS...COMPLEX TO MOVE EAST
AND SOUTHEAST. MODELS SUGGEST COMPLEX MOVING INTO NORTHERN CWA BY
AFTERNOON. HAVE EXPANDED POPS GIVEN SCENARIO.
TEMPERATURES TO CONTINUE TO RUN WARMER THAN NORMAL THIS
PERIOD...THOUGH COOLER THAN PREVIOUS FEW DAYS.
.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
ISSUED AT 405 AM CDT WED AUG 28 2013
ALTHOUGH THERE ARE SOME TIMING DIFFERENCES AMONG THE
MODELS...PRECIPITATION CHANCES SHOULD BE HIGHEST ON THURSDAY
NIGHT AS AN UPPER LEVEL SHORT WAVE TOPS THE RIDGE. THERE WILL ALSO
BE ASSISTANCE FROM SOME 300MB DIVERGENCE AND AN APPROACHING
SURFACE SYSTEM.
THUNDERSTORM CHANCES REMAIN FOR FRIDAY AND SATURDAY WITH WARM AND
HUMID AIR IN PLACE...BUT DO NOT REALLY SEE MUCH FORCING. A COLD
FRONT PUSHING THROUGH TO START NEXT WEEK WILL BRING A CHANCE OF
SHOWERS AND THUNDERSTORMS THROUGH SUNDAY...AND COOLER
TEMPERATURES FOR MONDAY AND TUESDAY.
HAVE GENERALLY USED A MIX OF GUIDANCE AND PREVIOUS FORECAST
TEMPERATURES FOR MAX AND MIN TEMPERATURES DURING THE PERIOD.
&&
.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 631 AM CDT WED AUG 28 2013
STRATUS OFF LAKES EXPANDED OVER REGION OVERNIGHT UNDER NE FLOW.
LINGERING FOG WILL CLEAR EARLY THIS MORNING...THOUGH THE LOW
CLOUDS WILL LINGER INTO MID TO LATE MORNING AS WEAK HIGH PRESSURE
BRINGS DRIER AIR MASS SOUTH. VFR CONDITIONS EXPECTED INTO CONTINUE
INTO THE EVENING...BEFORE FOG RETURNS AFTER MIDNIGHT. &&
.GRB WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 8 AM CDT THIS MORNING FOR WIZ005-
010>012-018-019.
&&
$$
SHORT TERM.....TE
LONG TERM......MG
AVIATION.......
AREA FORECAST DISCUSSION
NWS PUEBLO CO
454 AM MDT FRI AUG 30 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 453 AM MDT FRI AUG 30 2013
CURRENT WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS INDICATING LARGE
UPPER HIGH REMAINING IN PLACE ACROSS THE HIGH PLAINS THROUGH THE
ROCKIES WITH FASTER ZONAL FLOW NOTED ACROSS THE NORTHERN TIER OF
STATES AT THIS TIME. WATER VAPOR IMAGERY AND SATELLITE DATA
INDICATING AN INCREASE IN ATMOSPHERIC MOISTURE ACROSS SOUTH CENTRAL
AND SOUTHEAST COLORADO ALONG WITH AN EMBEDDED SHORT WAVE TRANSLATING
ACROSS THE NORTHERN GREAT BASIN AT THIS TIME. WARM AIR ALOFT ALSO
REMAINS IN PLACE UNDERNEATH THE UPPER HIGH WITH CURRENT TEMPS IN THE
MID 40S TO MID 50S ACROSS THE HIGHER TERRAIN AND 60S TO LOWER 70S
ACROSS THE LOWER ELEVATIONS AT THIS TIME.
TODAY AND TONIGHT...WITH A TAD MORE MOISTURE IN PLACE...ALONG WITH
TAIL END OF NORTHERN GREAT BASIN SHORT WAVE TRANSLATING ACROSS THE
NORTHERN PORTIONS OF THE STATE THIS AFTERNOON...SHOULD SEE AN
UPSWING IN CONVECTION OVER AND NEAR THE HIGH TERRAIN THIS AFTERNOON
AND EARLY EVENING...WITH BEST COVERAGE EXPECTED ACROSS THE CENTRAL
MTS. HAVE ALSO INCREASED POPS ACROSS TELLER COUNTY AND THE PALMER
DVD LATE THIS AFTERNOON AND EVENING WITH LATEST RUNS OF THE HIGHER
RESOLUTION HRRR AND RAP MODELS COMING MORE IN LINE WITH THE MORE
AGGRESSIVE NAM. AT ANY RATE...MODEL SOUNDINGS STILL INDICATING
CONVECTION TO BE RATHER HIGH BASED ACROSS THE EASTERN MTS WITH NOT
MUCH MEASURABLE PRECIPITATION EXPECTED. TEMPS AGAIN TO WARM RATHER
QUICKLY THIS MORNING...THOUGH WITH MORE CONVECTIVE CLOUD
COVER...SHOULD SEE HIGHS NEAR OR ONLY SLIGHTLY COOLER THAN
YESTERDAYS READINGS. COULD SEE NEAR RECORD HIGHS AT ALS (86F IN
2012) AND COS (94F IN 1990) ONCE AGAIN TODAY...THOUGH CURRENT RECORD
AT PUB OF 102F IN 1990 LOOKS SAFE.
CONVECTIVE DIMINISHES THROUGH THE EVENING WITH DEBRIS CLOUDS SLOWLY
DIMINISHING THROUGH THE OVERNIGHT...KEEPING LOWS GENERALLY ABOVE
SEASONAL AVERAGES.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 402 AM MDT FRI AUG 30 2013
...CHANCE FOR THUNDERSTORMS WITH LOCALLY HEAVY RAIN RETURNING TO
MOST AREAS THIS WEEKEND...
MODELS INDICATING THAT A SHORTWAVE AND LOW LEVEL FRONTAL SYSTEM WILL
DROP SOUTHEAST THROUGH THE CENTRAL PLAINS SATURDAY AFTERNOON AND
EVENING...RESULTING IN LOW LEVEL UPSLOPE ON THE PLAINS...AND TAPPING
MONSOON MOISTURE ALOFT. THE INTERACTION OF THE 2 WILL RESULT IN
FAIRLY WIDESPREAD CHANCES FOR SHOWERS AND THUNDERSTORMS DEVELOPING
ACROSS THE AREA SATURDAY AFTERNOON AND EVENING...WITH ENOUGH MOISTURE
PRESENT TO PRODUCE LOCALLY HEAVY RAINFALL. SO...THE THREAT OF
FLOODING WILL RAMP UP ONCE AGAIN FOR AREA BURN SCARS...AS WELL AS
FOR OTHER AREAS...AWAY FROM THE BURN SCARS. OTHER POSSIBLE THREATS
WILL INCLUDE LIGHTNING...GUSTY WINDS AND SMALL HAIL.
ELEVATED CHANCES FOR RAIN AND FLASH FLOODING WILL PROBABLY CONTINUE
FOR A LOT OF AREAS AT LEAST THROUGH SUNDAY. THERE ARE MIXED SIGNALS
FOR WHAT TO EXPECT ACROSS THE PLAINS ON SUNDAY. SOME MODEL RUNS
SHOW FAIRLY WIDESPREAD SHOWERS AND HEAVY RAIN POTENTIAL ACROSS THE
PLAINS ON SUNDAY...WHILE OTHERS HOLD ALL THE SHOWERS AND HEAVY RAIN
POTENTIAL BACK OVER THE MOUNTAINS AND HIGH VALLEYS. SO...IT SEEMS
PRETTY CLEAR THE MOUNTAINS AND HIGH VALLEYS WILL HAVE ANOTHER
ACTIVE DAY...BUT IT IS LESS CLEAR EXACTLY WHAT WILL HAPPEN ON THE
PLAINS. FOR NOW...FORECASTS ARE SORT OF SPLITTING THE DIFFERENCE...
KEEPING THE COVERAGE OF STORMS SOMEWHERE IN THE MIDDLE...GENERALLY
IN THE SCATTERED CATEGORY. IN ANY EVENT...WHATEVER STORMS MANAGE
TO FORM WILL ALSO HAVE THE POTENTIAL FOR LOCALLY HEAVY RAIN...SO
THE THREAT TO AREA BURN SCARS WILL REMAIN HIGH ON SUNDAY.
NEXT WEEK...IT APPEARS UPPER HIGH PRESSURE WILL REORGANIZE AND
RECENTER OVER EASTERN COLORADO. THIS WILL PROBABLY RESULT IN
CONTINUED MONSOON CONVECTION OVER THE MOUNTAINS...BUT WITH
DRIER AND WARMER CONDITIONS AGAIN OVER MOST OF THE PLAINS.
SOME ACTIVITY COULD CREEP EAST ACROSS THE PLAINS AT TIMES...
BUT THE BULK OF THE ACTIVITY WILL PROBABLY REMAIN OVER THE
HIGH COUNTRY. THIS MEANS THAT THE WATCH FOR FLASH FLOODING
ON AND NEAR AREA BURN SCARS WILL CONTINUE NEXT WEEK AS ALL
OF THE BURN SCARS WILL LIKELY REMAIN UNDER THE MONSOON
PLUME. LW
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 402 AM MDT FRI AUG 30 2013
VFR CONDITIONS EXPECTED FOR THE NEXT 24 HRS AT COS...PUB AND ALS
WITH LARGE UPPER HIGH IN PLACE ACROSS THE HIGH PLAINS THROUGH THE
ROCKIES. ENOUGH MOISTURE REMAINS IN PLACE UNDER RIDGE FOR ISOLATED
TO SCATTERED -TSRA OVER AND NEAR THE MOUNTAINS THIS AFTERNOON AND
EVENING. BEST COVERAGE OF TSRA EXPECTED ACROSS THE CONTDVD THOUGH
LOOKS TO BE BETTER COVERAGE OF STORMS ACROSS THE PIKES PEAK REGION
THAN YESTERDAY. STILL TOO LOW OF A CHANCE TO INCLUDE IN TAFS AT THIS
TIME.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MW
LONG TERM...LW
AVIATION...MW
AREA FORECAST DISCUSSION
NWS GRAY ME
937 AM EDT FRI AUG 30 2013
.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA
TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE SATURDAY
BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH THROUGH NEW
ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON TUESDAY.
&&
.NEAR TERM /UNTIL 8 PM THIS EVENING/...
930 AM...THE 12Z KGYX RAOB SHOWS THE MOISTURE TRAPPED BELOW THE
LOW LEVEL INVERSION. CONSEQUENTLY...I`VE INCREASED SKY GRIDS IN
THIS ESTF UPDATE AND LOWERED MAXIMUM TEMPERATURES A FEW DEGREES.
I ADJUSTED 1ST PERIOD GRIDS BASED ON SATELLITE TRENDS AND TO
REFLECT THE 13Z MESONET. NIL OTHER CHANGES. HAV A GUD DAY.
PREV DISC...
UPDATE...MINOR CHANGES TO REFLECT CURRENT OBSERVATIONAL TRENDS.
PREVIOUS DISCUSSION...STRATUS DECK FILLING BACK IN A LITTLE AS
NOCTURNAL COOLING AND WEAK LIFT CONTINUES N OF THE WARM FNT. THIS
SHOULD LIMIT MIN TEMPS THIS MORNING...AND IN FACT RAISE TEMPS A
FEW DEGREES ACROSS ERN AREAS THAT CLEARED OUT EARLIER.
LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE
AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY
AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR
AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH
PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE
NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING
THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND
TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST.
SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE
FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE
AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS.
HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT
MENTIONING IN THE GRIDS.
&&
.SHORT TERM /8 PM THIS EVENING THROUGH 6 PM SATURDAY/...
LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS
OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A
FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS
WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF
CLOUDS AND MILD MIN TEMPS.
ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE
AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE
BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER
INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL
SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE
FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY
MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER
VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND
CENTRAL MAINE AND NEW HAMPSHIRE.
THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY.
SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF
THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE
EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY
TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE
REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW
THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST
AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING.
THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR
INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR
DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR
CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR
CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND
SAT.
LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY.
THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN
CEILINGS AND VSBYS.
&&
.MARINE...
SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT.
LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5
FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
ES
AREA FORECAST DISCUSSION
NWS GRAY ME
659 AM EDT FRI AUG 30 2013
.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA
EARLY TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE
SATURDAY BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH
THROUGH NEW ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON
TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...MINOR CHANGES TO REFLECT CURRENT OBSERVATIONAL TRENDS.
PREVIOUS DISCUSSION...STRATUS DECK FILLING BACK IN A LITTLE AS
NOCTURNAL COOLING AND WEAK LIFT CONTINUES N OF THE WARM FNT. THIS
SHOULD LIMIT MIN TEMPS THIS MORNING...AND IN FACT RAISE TEMPS A
FEW DEGREES ACROSS ERN AREAS THAT CLEARED OUT EARLIER.
LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE
AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY
AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR
AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH
PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE
NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING
THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND
TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST.
SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE
FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE
AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS.
HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT
MENTIONING IN THE GRIDS.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS
OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A
FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS
WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF
CLOUDS AND MILD MIN TEMPS.
ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE
AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE
BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER
INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL
SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE
FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY
MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER
VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND
CENTRAL MAINE AND NEW HAMPSHIRE.
THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY.
SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF
THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE
EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY
TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE
REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW
THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST
AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING.
THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR
INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR
DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR
CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR
CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND
SAT.
LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY.
THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN
CEILINGS AND VSBYS.
&&
.MARINE...
SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT.
LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5
FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
LEGRO/JC
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1016 AM CDT FRI AUG 30 2013
.UPDATE...
REMOVED MENTION OF PRECIP OVER NRN WI THIS MORNING AND UPDATED
WORDING IN ZONE FORECAST. OTHERWISE...NO MAJOR CHANGES MADE TO THE
FORECAST.
&&
.PREV DISCUSSION... /ISSUED 643 AM CDT FRI AUG 30 2013/
AVIATION...12Z TAFS
A MVFR STRATUS DECK COVERED MUCH OF THE NORTHLAND THIS
MORNING. THE RAP 900/925MB PRES DEFICITS HAVE A DECENT HANDLE ON
THE CLOUDS...ALTHOUGH IT DOES SHOW THE CEILINGS A BIT TOO FAR TO
THE NORTH IN ONTARIO. WE SHOULD SEE CEILINGS SLOWLY RISE AND
BECOME SCATTERED EITHER LATER THIS MORNING OR THIS AFTERNOON. THEY
WILL HANG ON LONGEST OVER NORTHWEST WISCONSIN.
WE SHOULD ALSO SEE SOME CU DEVELOP TODAY WITH CONVECTIVE TEMPS
AROUND 70F. AFTER THIS STRATUS BREAKS UP...WE DID LEAVE CLOUDS
SCATTERED...BUT SOME BROKEN DECKS WILL BE POSSIBLE AS WELL.
TONIGHT...A WEDGE OF HIGH PRESSURE WILL CAUSE WINDS TO BE
LIGHT. SOME FOG WILL BE POSSIBLE...AND SOME MORE STRATUS MAY FORM
OVER OR AROUND LAKE SUPERIOR.
PREV DISCUSSION... /ISSUED 356 AM CDT FRI AUG 30 2013/
SHORT TERM...SFC LOW OVER CTRL LAKE SUPERIOR WITH TRAILING COLD
FRONT ACROSS NWRN WISC. POST FRONTAL CLOUDS ARE MOVING SOUTH UNDER
DEEPENING NRLY FLOW. AHEAD OF FRONT RESIDUAL STORMS DIMINISHING
OVER IRON COUNTY. MUCH OF CWA STILL UNDER MOIST ATMOSPHERE WITH
VERY SLOW REDUCTION IN SFC DEWPOINTS.
TODAY...WEDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION FROM
PARENT ANTICYCLONE NEAR HUDSON BAY. SFC DEWPOINTS WILL GRADUALLY
LOWER WITH SOME ASSISTANCE FROM BDRY LYR MIXING DURING THE DAY.
POST FRONTAL CLOUD COVER WILL TAKE A WHILE TO DIMINISH BASED ON
RAP13 925 CPD FCST. GENERAL CLOUD CANOPY SHOULD SLOWLY PUSH SOUTH
AND EAST INTO WISC ZONES DURING THE AFTN.
TONIGHT...SFC HIGH MOVES EAST OVERNIGHT AS SFC/MID LVL SYSTEM
MOVES INTO NRN PLAINS. WARM ADVECTION REGIME BEGINS BY 12Z SAT
OVER WRN CWA. MIN TEMPS LOWEST OVER INTERIOR WISC ZONES AND ERN
ARROWHEAD WHERE MAX RAD COOLING POTENTIAL EXISTS. TEMPS MAY NEED
ADJUSTMENT OVERNIGHT NEAR BORDERLAND AS INITIAL MID LVL WARM
ADVECTION CLOUDS MAY BE MORE EXTENSIVE THEN CURRENTLY FCST.
TOMORROW...A MID LVL TROF WITH AN ASSOCIATED SFC LOW WILL MOVE
INTO ONTARIO WITH A TRAILING COLD FRONT APPROACHING WRN EDGE OF CWA
BY LATE AFTN. INCREASING SRLY/SWRLY BDRY LYR FLOW WILL BECOME MORE
UNSTABLE IN THE AFTN. RW/TRW WILL DEVELOP OVER KOOCH COUNTY AROUND
MIDDAY AND GRADUALLY SPREAD EAST AND SOUTH TOWARDS TWIN PORTS BY
LATE AFTN. MAX TEMPS WILL PUSH ABOVE CLIMO ONCE AGAIN OVER MOST OF
THE CWA.
SATURDAY NIGHT THROUGH THURSDAY.
MAIN FOCUS IN THE EXTENDED PERIOD WILL BE A SHORTWAVE AND COLD FRONT
SATURDAY NIGHT.
THE MODELS ARE IN PRETTY DECENT AGREEMENT WITH A STRONG SHORTWAVE
AND COLD FRONT MOVING THROUGH THE REGION SATURDAY NIGHT. THE
STRONGEST PORTION OF THE WAVE WILL RIDE THE INTERNATIONAL BORDER.
PWAT VALUES AROUND 1.5 INCHES WILL BE OVER THE NORTHLAND AS THESE
FEATURES MOVE THROUGH. WE HAVE A GOOD CHANCE FOR SHOWERS AND STORMS
OVER MUCH OF THE NORTHLAND SATURDAY NIGHT. SOME OF THESE STORMS
COULD BE QUITE STRONG BUT WHETHER OR NOT THEY WILL BE SEVERE IS
STILL QUESTIONABLE. ADEQUATE SHEAR IS IN PLACE WHICH SUPPORTS
STRONGER STORMS.
THE CHANCE FOR SHOWERS AND A FEW THUNDERSTORMS WILL LINGER INTO
SUNDAY OVER PORTIONS OF THE NORTHLAND AS THE UPPER TROUGH SWINGS
THROUGH AND DUE TO COLDER AIR ALOFT. IT WILL BE MUCH COOLER...WITH
HIGHS FROM 65 TO 70 NORTH...AND THE MID SEVENTIES OVER OUR FAR
SOUTHEAST ZONES.
HIGH PRESSURE WILL TAKE HOLD MONDAY...AND PROVIDE DRY WEATHER INTO
THURSDAY. TEMPERATURES WILL SLOWLY INCREASE DURING THIS TIME...GOING
FORM THE MID SIXTIES TO LOWER SEVENTIES MONDAY...RISING THROUGH THE
SEVENTIES BY THURSDAY.
&&
.POINT TEMPS/POPS...
DLH 78 57 81 61 / 10 0 50 50
INL 79 60 83 57 / 10 20 50 50
BRD 81 60 87 60 / 10 10 50 50
HYR 79 56 85 63 / 20 0 10 60
ASX 74 57 80 63 / 20 0 10 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...TENTINGER
AREA FORECAST DISCUSSION
NWS DULUTH MN
643 AM CDT FRI AUG 30 2013
.AVIATION...12Z TAFS
A MVFR STRATUS DECK COVERED MUCH OF THE NORTHLAND THIS
MORNING. THE RAP 900/925MB PRES DEFICITS HAVE A DECENT HANDLE ON
THE CLOUDS...ALTHOUGH IT DOES SHOW THE CEILINGS A BIT TOO FAR TO
THE NORTH IN ONTARIO. WE SHOULD SEE CEILINGS SLOWLY RISE AND
BECOME SCATTERED EITHER LATER THIS MORNING OR THIS AFTERNOON. THEY
WILL HANG ON LONGEST OVER NORTHWEST WISCONSIN.
WE SHOULD ALSO SEE SOME CU DEVELOP TODAY WITH CONVECTIVE TEMPS
AROUND 70F. AFTER THIS STRATUS BREAKS UP...WE DID LEAVE CLOUDS
SCATTERED...BUT SOME BROKEN DECKS WILL BE POSSIBLE AS WELL.
TONIGHT...A WEDGE OF HIGH PRESSURE WILL CAUSE WINDS TO BE
LIGHT. SOME FOG WILL BE POSSIBLE...AND SOME MORE STRATUS MAY FORM
OVER OR AROUND LAKE SUPERIOR.
&&
.PREV DISCUSSION... /ISSUED 356 AM CDT FRI AUG 30 2013/
SHORT TERM...SFC LOW OVER CTRL LAKE SUPERIOR WITH TRAILING COLD
FRONT ACROSS NWRN WISC. POST FRONTAL CLOUDS ARE MOVING SOUTH UNDER
DEEPENING NRLY FLOW. AHEAD OF FRONT RESIDUAL STORMS DIMINISHING
OVER IRON COUNTY. MUCH OF CWA STILL UNDER MOIST ATMOSPHERE WITH
VERY SLOW REDUCTION IN SFC DEWPOINTS.
TODAY...WEDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION FROM
PARENT ANTICYCLONE NEAR HUDSON BAY. SFC DEWPOINTS WILL GRADUALLY
LOWER WITH SOME ASSISTANCE FROM BDRY LYR MIXING DURING THE DAY.
POST FRONTAL CLOUD COVER WILL TAKE A WHILE TO DIMINISH BASED ON
RAP13 925 CPD FCST. GENERAL CLOUD CANOPY SHOULD SLOWLY PUSH SOUTH
AND EAST INTO WISC ZONES DURING THE AFTN.
TONIGHT...SFC HIGH MOVES EAST OVERNIGHT AS SFC/MID LVL SYSTEM
MOVES INTO NRN PLAINS. WARM ADVECTION REGIME BEGINS BY 12Z SAT
OVER WRN CWA. MIN TEMPS LOWEST OVER INTERIOR WISC ZONES AND ERN
ARROWHEAD WHERE MAX RAD COOLING POTENTIAL EXISTS. TEMPS MAY NEED
ADJUSTMENT OVERNIGHT NEAR BORDERLAND AS INITIAL MID LVL WARM
ADVECTION CLOUDS MAY BE MORE EXTENSIVE THEN CURRENTLY FCST.
TOMORROW...A MID LVL TROF WITH AN ASSOCIATED SFC LOW WILL MOVE
INTO ONTARIO WITH A TRAILING COLD FRONT APPROACHING WRN EDGE OF CWA
BY LATE AFTN. INCREASING SRLY/SWRLY BDRY LYR FLOW WILL BECOME MORE
UNSTABLE IN THE AFTN. RW/TRW WILL DEVELOP OVER KOOCH COUNTY AROUND
MIDDAY AND GRADUALLY SPREAD EAST AND SOUTH TOWARDS TWIN PORTS BY
LATE AFTN. MAX TEMPS WILL PUSH ABOVE CLIMO ONCE AGAIN OVER MOST OF
THE CWA.
SATURDAY NIGHT THROUGH THURSDAY.
MAIN FOCUS IN THE EXTENDED PERIOD WILL BE A SHORTWAVE AND COLD FRONT
SATURDAY NIGHT.
THE MODELS ARE IN PRETTY DECENT AGREEMENT WITH A STRONG SHORTWAVE
AND COLD FRONT MOVING THROUGH THE REGION SATURDAY NIGHT. THE
STRONGEST PORTION OF THE WAVE WILL RIDE THE INTERNATIONAL BORDER.
PWAT VALUES AROUND 1.5 INCHES WILL BE OVER THE NORTHLAND AS THESE
FEATURES MOVE THROUGH. WE HAVE A GOOD CHANCE FOR SHOWERS AND STORMS
OVER MUCH OF THE NORTHLAND SATURDAY NIGHT. SOME OF THESE STORMS
COULD BE QUITE STRONG BUT WHETHER OR NOT THEY WILL BE SEVERE IS
STILL QUESTIONABLE. ADEQUATE SHEAR IS IN PLACE WHICH SUPPORTS
STRONGER STORMS.
THE CHANCE FOR SHOWERS AND A FEW THUNDERSTORMS WILL LINGER INTO
SUNDAY OVER PORTIONS OF THE NORTHLAND AS THE UPPER TROUGH SWINGS
THROUGH AND DUE TO COLDER AIR ALOFT. IT WILL BE MUCH COOLER...WITH
HIGHS FROM 65 TO 70 NORTH...AND THE MID SEVENTIES OVER OUR FAR
SOUTHEAST ZONES.
HIGH PRESSURE WILL TAKE HOLD MONDAY...AND PROVIDE DRY WEATHER INTO
THURSDAY. TEMPERATURES WILL SLOWLY INCREASE DURING THIS TIME...GOING
FORM THE MID SIXTIES TO LOWER SEVENTIES MONDAY...RISING THROUGH THE
SEVENTIES BY THURSDAY.
&&
.POINT TEMPS/POPS...
DLH 78 57 81 61 / 10 10 20 50
INL 82 60 83 57 / 10 10 50 50
BRD 84 60 87 60 / 10 0 30 50
HYR 81 56 85 63 / 20 0 10 60
ASX 76 57 80 63 / 20 0 10 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...CANNON
LONG TERM....MELDE
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
638 AM PDT FRI AUG 30 2013
.SYNOPSIS...A MOIST AND UNSTABLE ATMOSPHERE WILL ALLOW FOR SHOWERS
AND THUNDERSTORMS TO DEVELOP ACROSS THE AREA THROUGH THIS WEEKEND
WITH THE GREATEST CHANCES IN THE AFTERNOON AND EVENING HOURS. THE
PRIMARY HAZARD WITH THUNDERSTORMS WILL BE HEAVY RAINFALL THAT COULD
RESULT IN FLASH FLOODING. THUNDERSTORM CHANCES ARE EXPECTED TO
DECREASE SLIGHTLY FROM MONDAY ONWARD.
&&
.UPDATE...SHOWERS AND THUNDERSTORMS HAVE DEVELOPED FARTHER WEST THAN
EXPECTED THIS MORNING WITH MEASURABLE RAIN HAVING MOVED INTO
HENDERSON. UPDATED THE FORECAST TO ACCOUNT FOR THIS TREND.
&&
.PREV DISCUSSION...
225 AM PDT FRI AUG 30 2013
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT. WHAT WAS LEFT OF THE
CONVECTIVE COMPLEX THAT DEVELOPED OVER MOHAVE COUNTY YESTERDAY
AFTERNOON WAS GONE, HOWEVER, THE FOCUS EARLY THIS MORNING ON RADAR
NOW SHIFTS TO ONGOING CONVECTION ACROSS YAVAPAI AND COCONINO
COUNTIES IN ARIZONA THAT WAS MOVING WESTWARD. THE HRRR MODEL DID NOT
DO A BAD JOB INDICATING THIS. THUS USING A BLEND OF THIS MODEL AND
THE LATEST RADAR TRENDS, I WENT AHEAD AND ADJUSTED UP POPS ACROSS
MUCH OF MOHAVE COUNTY FOR EARLY THIS MORNING AS IT APPEARS MUCH OF
THIS ACTIVITY SHOULD HAVE A CHANCE AT MAKING IT OVER THE BORDER INTO
OUR AREA. THE CLOUD COVER ASSOCIATED WITH THIS AS WELL AS WHAT
REMAINS FROM THE CLOUD COVER FROM THE CONVECTIVE COMPLEX THAT FORMED
ON THURSDAY AFTERNOON WILL PRESENT A BIT OF A CHALLENGE AS THIS
COULD LIMIT HEATING LATER TODAY OVER MOHAVE COUNTY WHICH MAY DELAY
OR INHIBIT CONVECTION ALTOGETHER IN THIS AREA.
AS FAR AS WHAT GOES ON THIS AFTERNOON AND EVENING, ACTIVITY WILL BE
DRIVEN BY HEATING WITH PERHAPS SOME HELP FROM A WEAK DISTURBANCE AND
INVERTED TROUGH IN THE MID-LEVELS WORKING NORTHWEST ACROSS SOCAL.
SERIOUS MOISTURE REMAINS IN PLACE ACROSS OUR ENTIRE AREA WITH
PWATS REMAINING IN THE UPPER REACHES OF CLIMATOLOGY FOR THIS AREA,
WITH VALUES AT OR ABOVE 1.75 INCHES FORECAST TO BE AROUND FROM I-15
ON SOUTH. FORECASTED 700-300 MB THETA E VALUES ARE SHOWN TO BE AT
LEAST 340 K ACROSS MOST OF AREA AS WELL. A LOOK AT INSTABILITY
PARAMETERS OFF THE MODELS SHOWS INSTABILITY IN PLACE ACROSS OUR
ENTIRE AREA, HOWEVER, BOTH THE GFS AND ECMWF SHOW THE GREATEST LI`S
OF -2 TO -4 ACROSS MOHAVE, CLARK AND SOUTHERN NYE COUNTIES. SO WHILE
WE COULD SEE SHOWERS AND THUNDERSTORMS ACROSS ANY PORTION OF THE
AREA THIS AFTERNOON AND EVENING, ODDS LOOK TO FAVOR AN AREA WITHIN
75 MILES ON EITHER SIDE OF A LINE FROM NEAR LONE PINE TO LAS VEGAS
TO KINGMAN AS THE MOST ACTIVE LOCATIONS. THUS I WENT AHEAD AND
ISSUED A FLASH FLOOD WATCH FOR MOST OF MOHAVE, ALL OF CLARK,
SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND ALL OF INYO COUNTY EXCEPT
THE WHITE MOUNTAINS FROM LATE THIS MORNING THROUGH THIS EVENING AS
WITH SO MUCH MOISTURE IN PLACE THE UNLOAD POTENTIAL WILL BE THERE IN
ANY STRONGER OR SLOWER MOVING STORMS. THE STEERING FLOW SHOWN BY THE
WRF AND GFS IS GENERALLY LIGHT AND FROM THE EAST TODAY, HOWEVER, BY
THIS EVENING IT DOES TAKE ON MORE OF A NORTHEAST COMPONENT. THUS,
THIS MAY BE ONE OF THOSE DAYS WHERE STORMS DO NOT AFFECT THE LAS
VEGAS VALLEY UNTIL LATER THIS EVENING AS WE MAY HAVE TO WAIT FOR
ACTIVITY TO HEAD IN FROM NORTHWEST ARIZONA, NORTHEAST CLARK COUNTY
OR SOUTHWEST UTAH. ACTIVITY SHOULD DECREASE LATER THIS EVENING,
HOWEVER, CLOUDS MAY NOT COMPLETELY CLEAR OUT TONIGHT, WHICH COULD
IMPACT THE FORECAST FOR SATURDAY.
AS FAR AS SATURDAY GOES, RIDGING ALOFT WILL REMAIN CENTERED OVER THE
SOUTHWEST AND THIS WILL KEEP OUR AREA IN A SOUTHEAST FLOW ALOFT
WHICH WILL ALLOW FOR WHATEVER MOISTURE IS IN PLACE TO REMAIN WITH THE
POTENTIAL FOR ADDITIONAL MOISTURE TO WORK INTO THE AREA. ACTIVITY ON
SATURDAY WILL DEPEND ON HEATING AND THUS IF WE START OFF TOO CLOUDY
THIS COULD LIMIT WHAT WE SEE WITH RESPECT TO SHOWER AND THUNDERSTORM
ACTIVITY. THE 00Z RUNS OF THE WRF, GFS, ECMWF AS WELL AS OUR LOCAL
HI-RESOLUTION MODELS FAVORED ACTIVITY DEVELOPING MAINLY ACROSS
SOUTHERN NEVADA, INYO AND NORTHERN AND CENTRAL MOHAVE COUNTY WITH
LESS ACTIVITY FURTHER SOUTH ON THE BACK SIDE OF THE INVERTED TROUGH.
FOR NOW WE HAVE HELD OFF ON ANY FLASH FLOOD WATCHES FOR SATURDAY,
BUT WITH SO MUCH MOISTURE IN PLACE, THE MAIN CONCERN IN STORMS AGAIN
WILL BE FLASH FLOODING.
TEMPS WILL CONTINUE TO REMAIN BELOW NORMAL FOR HIGHS AND AT OR ABOVE
NORMAL FOR LOWS. I USED A BLEND OF PERSISTENCE, THE SREF AND ECMWF
FOR MAX TEMPS AND CONTINUITY AND MOS GUIDANCE FOR MIN TEMPS.
DEWPOINTS WERE ADJUSTED UP SLIGHTLY OVER GUIDANCE GIVEN HOW MOIST WE
HAVE BEEN THE PAST 2 DAYS AND IT SEEMS MODELS HAVE BEEN A LITTLE LOW
ON PICKING UP ON THIS.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...MODELS IN PRETTY GOOD
AGREEMENT SUNDAY NIGHT THROUGH TUESDAY WITH A PRETTY GENERIC MONSOON
PATTERN AND NO SIGNIFICANT WAVES IMPACTING THE AREA. HIGH PRESSURE
IS FORECAST ROUGHLY OVER THE COLORADO AND NEW MEXICO BORDER AREA
WITH AN AREA OF LOW PRESSURE OFF THE PACIFIC NORTHWEST COAST.
SOUTHERLY FLOW OVER THE FORECAST AREA WILL KEEP MONSOON MOISTURE
AROUND WITH THE DEEPEST MOISTURE OVER THE EASTERN PORTION OF THE
FORECAST AREA AS IS TYPICAL WITH THIS PATTERN. AS A RESULT WE ARE
STILL LOOKING AT A CHANCE OF THUNDERSTORMS EAST WITH A SLIGHT CHANCE
WEST. MODELS DIFFER FOR WEDNESDAY THROUGH THURSDAY WITH THE GFS AND
TO A LESSER EXTENT THE GEM MOVING THE AREA OF LOW PRESSURE INLAND.
THIS WOULD BRING DRIER AIR INTO THE AREA FROM THE WEST. THE ECMWF IS
EXPANDING THE HIGH WESTWARD WHICH MAY KEEP A BIT MORE MOISTURE IN
PLACE BUT ALSO COULD LEAD TO WARMING AND SOME STABILIZING. BASICALLY
GOING WITH A BLEND...I MADE LITTLE CHANGE TO THE INHERITED GRIDS AND
KEPT AT LEAST A SLIGHT CHANCE OVER THE EASTERN TWO THIRDS OF THE
FORECAST AREA WHILE DRYING THE WEST BY THURSDAY. ALSO WENT WITH A
WARMING TREND AND ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY.
&&
.AVIATION...FOR MCCARRAN...SHRA/TSRA ARE EXPECTED TO BE AROUND THE
VALLEY MAINLY AFTER 18Z AND ESPECIALLY AFTER 20Z TODAY. SHRA AND
TSRA ARE EXPECTED TO MOVE IN A WEST TO SOUTHWEST DIRECTION THIS
AFTERNOON AND EVENING SO ACTIVITY THAT DEVELOPS OVER NW AZ OR
NORTHEAST CLARK COUNTY WILL NEED TO BE WATCHED - ESPECIALLY FOR ANY
OUTFLOW BOUNDARIES. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS BUT
OTHERWISE COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA OR
OUTFLOW BOUNDARIES WHICH COULD IMPACT AIRPORT CONFIGURATIONS. MAINLY
SCT-BKN CLOUDS AOA 10K-15K FEET WITH LOWER CIGS AND VSBY IN AND NEAR
ANY SHRA/TSRA. ACTIVITY SHOULD DECREASE BETWEEN 03Z AND 06Z SATURDAY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...SHRA/TSRA ARE EXPECTED ACROSS THE AREA AFTER 18Z AND
ESPECIALLY AFTER 20Z TODAY WITH THE GREATEST COVERAGE ACROSS MOHAVE,
CLARK, SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND INYO COUNTIES.
SHRA AND TSRA SHOULD FAVOR A SLOW WESTWARD MOVEMENT ACROSS MOST OF
THE AREA. SHRA/TSRA COULD REDUCE VSBY AND CIGS TO MVFR OR LOWER.
WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS THROUGH THIS EVENING BUT
COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA. SCT-BKN CLOUDS
AOA 10K-15K FEET AWAY FROM ANY SHRA/TSRA.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR NVZ016>022.
AZ...FLASH FLOOD WATCH FROM 11 AM MST THIS MORNING THROUGH THIS
EVENING FOR AZZ001-003-036.
CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR CAZ519-520-522-524.
&&
$$
UPDATE...HARRISON
SHORT TERM/AVIATION...STACHELSKI
LONG TERM...HARRISON
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1030 AM EDT FRI AUG 30 2013
.SYNOPSIS...
RAIN-FREE CONDITIONS ARE EXPECTED TODAY...ALONG WITH A
CONTINUATION OF WARM TEMPERATURES...AS A RIDGE OF HIGH PRESSURE
RESIDES ALONG THE EAST COAST. STARTING TONIGHT...AND THEN LASTING
THROUGH THE WEEKEND...OUR WEATHER WILL BECOME MORE UNSETTLED...AS
A SLOWLY APPROACHING FRONTAL BOUNDARY...ALONG WITH PASSING UPPER-
LEVEL DISTURBANCES...BRING PERIODIC BOUTS OF SHOWERS AND
THUNDERSTORMS. IT WILL ALSO REMAIN QUITE WARM...AND INCREASINGLY
MUGGY...THROUGHOUT THE HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1015 AM UPDATE...
FOG IS BURNING OFF AND IS EXPECTED TO RESULT IN PARTLY-MOSTLY
SUNNY SKIES THIS AFTN. THIS WL ALLOW TEMPS TO RISE CLOSE TO YDA`S
VALUES IN THE L/M 80S. WL KEEP AN EYE ON AREA OF SHOWERS MVNG
INTO LKS ERIE AND ONTARTIO AHD OF WK INITIAL S/WV. THIS WV WL
PROPAGATE INTO WRN PART OF CWA AFT 21Z AND LATEST HRRR BRINGS
CONVECTION INTO FA LATE THIS AFTN.
A STRONG S/WV IS NOW ROTATING ACRS LK SUPERIOR AND IS MAKING A
BEELINE FOR THE CWA FOR THE OVRNGT HRS. CURRENT THINKING IS THAT
WIND SHEAR VALUES WL INCREASE BTWN 03Z AND 06Z AND WL LOOK TO UP
POPS WITH THE AFTN PACKAGE. POTENTIAL EXISTS FOR STRONG WINDS AND
TORRENTIAL DOWNPOURS TONIGHT, ESPECIALLY FOR NRN ZONES. PW VALUES
INCREASE TO NEAR 1.60 INCHES WHICH IS 1-2 STANDARD DEVIATIONS ABV
NORMAL. H8 FLOW ONLY INCREASES TO NEAR 20KTS BY THIS TIME SO THINK
THE BIGGEST THREAT WL BE LOCALLY HVY RAINFALL AND PLAN TO UPDATE
HWO ACCORDINGLY.
PREV DISCO BLO...
4 AM FRI UPDATE... LWR STRATUS CLDS AND FOG HAVE BECOME WIDESPREAD
ONCE AGN EARLY THIS MRNG. MUCH LIKE YDY...GIVEN A MOIST BLYR
ENVIR...AND WEAK FLOW/VERT MIXING...IT WILL LIKELY TAKE A WHILE
FOR THE FOG TO LIFT...AND THE CLDS TO BREAK UP (13-15Z).
BY MIDDAY/EARLY AFTN...THE EARLIER MRNG STRATUS LYR SHOULD EVOLVE
INTO A SCT-BKN CU FIELD...WITH OCNL HIGHER-LVL CLOUD DEBRIS ALSO COMING
IN FROM THE NW (EMANATING FROM UPSTREAM CONVECTION).
OVERALL...PTLY SUNNY SEEMS LIKE A GOOD SKY COVER DESCRIPTOR. GIVEN
SIMILAR 925-850 MB TEMPS TO THU...AND ALSO A FAIRLY SIMILAR DEGREE
OF INSOLATION...MAX TEMPS SHOULD ONCE AGN RANGE FROM THE UPR 70S OVER
THE HIGHER TERRAIN OF THE CATSKILLS...TO THE UPR 80S IN PTNS OF
THE FINGER LKS RGN...AND OUR LAKE PLAIN CNTYS.
AS FAR AS CONVECTIVE POTENTIAL...WE THINK THE VAST MAJORITY OF THE DAY...IF
NOT THE ENTIRE DAY...WILL BE DEVOID OF ANY SHWRS/TSTMS. THE S/WV
WHICH PASSED THROUGH OUR RGN EARLY LAST EVE...IS NOW DOWN OVER
ERN VA...WITH DVM ALOFT/MID-LVL CAPPING EXPECTED TO REMAIN OVER
CNY/NE PA FOR A GOOD PTN OF THE DAY. THE NEXT S/WV UPSTREAM (SEEN
ON WATER VAPOR IMAGERY OVER NRN MI ATTM) IS NOT EXPECTED TO
APPROACH/BEGIN IMPACTING THE FA TIL ARND...OR AFTER 00Z. GIVEN THE
LIKELIHOOD OF 1000-1500 ML CAPES LTR TDY...WE CAN`T COMPLETELY
RULE OUT AN ISOLD TSTM OVER THE CATSKILLS/POCONOS...OR NEAR ANY
LAKE CONV BNDRYS DURG PEAK HEATING. HOWEVER..WE DON`T FEEL SUCH
COVERAGE/POTENTIAL (UNDER 10-15%) JUSTIFIES INCLUSION IN THE FCST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
420 AM FRI UPDATE... THE ABV REFERENCED S/WV OVER THE NRN LKS RGN
EARLY THIS MRNG...IS PROGGED TO TRACK NEAR LK ONT/UPSTATE NY
THIS EVE. FORCING FROM THIS FEATURE SHOULD CAUSE AN INCREASE IN
CONVECTIVE COVERAGE AFTER DARK....AND WE`LL THUS CARRY SCTD
SHWRS/TSTMS MOST AREAS...WITH A SMALL WINDOW FOR THE LIKELIHOOD OF
SUCH ACTIVITY IN OUR FAR NRN ZNS (03-09Z).
FOR THE NEXT COUPLE OF DAYS (SAT-SUN)...WE`RE EXPECTING A SCENARIO
FEATURING THE PASSAGE OF SVRL S/WVS (SOME PERHAPS CONVECTIVELY
INDUCED FROM UPSTREAM)...AND ALSO THE GRADUAL APPROACH OF A SFC FRONTAL
BNDRY...ULTIMATELY EXPECTED TO LIE JUST N/W OF THE CWA BY SAT
NGT/SUN. AFTER TNT`S ROUND OF SHWRS/TSTMS (FAIRLY HIGH CONFIDENCE
FCST)...THE TIMING OF SUBSEQUENT CONVECTIVE ROUNDS BCMS DIFFICULT
TO PIN DOWN THIS FAR OUT. THUS...FOR NOW...WE`LL SIMPLY MAINTAIN
CONTINUITY...AND RETAIN OUR FCST OF SCTD SHWRS/TSTMS...WITH THIS
ACTIVITY LIKELY TO PEAK DURG MAX HEATING/DESTABILIZATION EACH
AFTN/EARLY EVE. SOMEWHAT HIGHER POPS WILL BE INDICATED FOR NRN/WRN
PTNS OF THE FA (40-50%...VERSUS 20-30% DOWN OVER NE PA)...CLOSER
TO THE ABV MENTIONED FRNT. ALL OF THIS BEING SAID...THIS WEEKEND
WILL NOT BE A COMPLETE WASHOUT (SHWRS/TSTMS SCTD IN
NATURE)...WITH SIG RAIN-FREE PDS ANTICIPATED...IN BETWEEN
CONVECTIVE WAVES.
ALTHOUGH THE ENVIR IS LIKELY TO BECOME QUITE UNSTABLE BOTH SAT
AND SUN AFTNS (ML CAPES OF 1500-2500)...MODEL CONSENSUS SHOWS THE
DEEP-LYRD SHEAR TO BE FAIRLY WEAK (0-6 KM VALUES OF ONLY 15-20 KT
MUCH OF THE TIME). THUS...TSTMS SHOULD BE LARGELY NON-SVR (GARDEN
VARIETY)...WITH PERHAPS AN ISOLD PULSE-TYPE SVR STORM AT WORST.
WARM MUGGY CONDS WILL REMAIN AT PLAY THIS PD (DAYTIME HIGHS WELL
INTO THE 80S...AND NIGHT-TIME LOWS IN THE 60S-NEAR 70).
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
430 AM FRI UPDATE... LITTLE TO CHANGE FROM THE PREVIOUS FORECAST
FROM YESTERDAY AFTERNOON. THE LONGER RANGE MODELS ARE IN GOOD
AGREEMENT WITH A TROF EARLY IN THE PERIOD ALONG WITH A SHOT OF
COOLER WEATHER THROUGH MID-WEEK. BY THURSDAY ANOTHER FRONT MOVES
THROUGH THE AREA WITH A CHANCE OF SHOWERS. IT WILL BE INTERESTING
WITH RESPECT TO WHAT HAPPENS WITH THIS SECOND TROF LATER IN THE
WEEK. THE NEW 0Z EURO IS MUCH SHARPER WITH THE TROF WITH 850 TEMPS
AS CHILLY AS -2C BY 12Z FRIDAY ACROSS NY STATE. MEANWHILE THE GFS
HAS 850 TEMPS OF +16C DURING THE SAME TIME. TALK ABOUT A
DIFFERENCE! NO CLEAR SIGN WHICH WAY TO LEAN AT THIS POINT WITH THE
CANADIAN FAVORING THE GFS...WHILE SOME OF THE GFS ENSEMBLES
FAVORING THE EURO. WILL BE FUN TO WATCH AS WE TURN TOWARD FALL.
THE PREVIOUS AFD IS BELOW...
PREV DISC... 3 PM EDT UPDATE... MADE MINOR ADJUSTMENTS TO THE
PREVIOUS FORECAST. A STRONG UPPER LEVEL TROUGH DIPS SOUTH OUT OF
CANADA ON SUNDAY ACROSS THE UPPER GREAT PLAINS AND THEN MOVES
EASTWARD TOWARDS THE GREAT LAKES ON MONDAY. THE INFLUENCE FROM
THIS SYSTEM WILL BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS
MONDAY NIGHT THROUGH WEDNESDAY. THE UPPER LOW WILL CONTINUE TO
MIGRATE EASTWARD AND MOVE OFF THE EAST COAST BY WEDNESDAY NIGHT.
THE ECMWF IS SLIGHTLY STRONGER THAN THE GFS...HOWEVER BOTH ARE IN
PRETTY GOOD AGREEMENT ON THE PLACEMENT OF THE TRACK OF UPPER LOW.
THURSDAY ANOTHER UPPER LOW WILL MOVE NORTH OF THE REGION POSSIBLY
BRINGING A COLD FRONT TO THE AREA.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
700 AM UPDATE...
DENSE FOG WILL PRODUCE WIDESPREAD RESTRICTIONS FOR THE NEXT FEW
HOURS OUTSIDE OF KSYR.
WORST CONDITIONS WILL BE AT KITH AND BGM. LIFR CONDITIONS
CONTINUE HERE THROUGH 13Z BEFORE SLOW IMPROVEMENT TO
VFR BY 15Z.
KAVP AND KRME...IFR CIGS AND VSBYS WILL SLOWLY IMPROVE TO VFR BY
15Z.
AFTER MID MORNING VFR IS EXPECTED THE REST OF TODAY.
NEAR CALM CONDITIONS THROUGH DAYBREAK. WINDS INCREASE TO 4 TO 8
KTS 13 TO 16Z AND REMAIN THROUGH THE AFTN.
OUTLOOK...
FRI NGT...GENERALLY VFR SOME MVFR POSSIBLE NORTHERN TERMINALS IN
SHOWERS/STORMS.
SAT-TUES...POTENTIAL FOR MVFR IN SCTD SHRA/TSRAS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MLJ
NEAR TERM...MLJ/PVN
SHORT TERM...MLJ
LONG TERM...KAH
AVIATION...HEDEN
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1022 AM CDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 1021 AM CDT FRI AUG 30 2013
CANCELLED THE DENSE FOG ADVISORY FOR CENTRAL NORTH DAKOTA AS THE
15 UTC OBSERVATIONS AND WEBCAMS SHOW ALL FOG HAS BURNED OFF ACROSS
THE AREA.
THE FOCUS REMAINS ON SEVERE CONVECTIVE DEVELOPMENT LATE THIS
AFTERNOON AND INTO THE EVENING. THE 13 UTC HRRR CONTINUES THE
TREND SUPPORTED BY THE 00 UTC 4 KM WRF AND SPC SSEO OF INITIATING
CONVECTION ALONG THE PRE-FRONTAL TROUGH BETWEEN HIGHWAY 85 AND 83
BETWEEN 20-22 UTC. -10 TO -30 HAIL CAPE VALUES OF 700-900 J/KG
WITH DEEP LAYER SHEAR OF 40-50 KTS SUGGESTS LARGE HAIL WILL BE A
PRIMARY THREAT...ALONG WITH DAMAGING WINDS WITH DOWNDRAFT CAPE
VALUES AOA 1000 J/KG. LOCALLY HEAVY RAINFALL IS ALSO EXPECTED WITH
PWATS NEAR 1.50 INCHES. WHILE THE TORNADIC THREAT IS LOW...ANY
SUPERCELLS THAT CAN INTERACT WITH THE TROUGH MAY PRESENT A
LOCALIZED THREAT FOR TORNADOES.
UPDATE ISSUED AT 714 AM CDT FRI AUG 30 2013
QUICK UPDATE TO ISSUE A DENSE FOG ADVISORY FOR MUCH OF CENTRAL
NORTH DAKOTA GIVEN THE 12 UTC FOG CHANNEL...SURFACE OBSERVATIONS
AND WEBCAMS.
UPDATE ISSUED AT 624 AM CDT FRI AUG 30 2013
UPDATE TO ADD AREAS OF DENSE FOG FROM HARVEY THROUGH
JAMESTOWN...AND PATCHY DENSE FOG WESTWARD THROUGH THE HIGHWAY 83
CORRIDOR. DENSE FOG NOT CONSIDERED WIDESPREAD ENOUGH FOR ADVISORY
AT THIS TIME. OTHERWISE...CURRENT FORECAST IN GOOD SHAPE. SCATTERED
THUNDERSTORMS EXPECTED WEST THIS AFTERNOON...SPREADING EAST
TONIGHT...SOME POSSIBLY SEVERE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 335 AM CDT FRI AUG 30 2013
CURRENTLY...SURFACE HIGH PRESSURE EXTENDED FROM MANITOBA SOUTHWARD
ACROSS CENTRAL NORTH DAKOTA INTO WESTERN SOUTH DAKOTA. A SURFACE
FRONT EXTENDED FROM A LOW OVER SOUTHERN ALBERTA TO CENTRAL MONTANA.
AT UPPER LEVELS...A SHORTWAVE EXTENDED FROM NORTHERN
ALBERTA/SASKATCHEWAN SOUTHWARD ACROSS CENTRAL MONTANA. THIS UPPER
LEVEL SHORTWAVE FEATURE WAS ASSOCIATED WITH A SCATTERED LINE OF
SHOWERS AND THUNDERSTORMS MOVING EASTWARD ACROSS CENTRAL MONTANA AND
SOUTH CENTRAL SASKATCHEWAN.
THE LATEST MODEL RUNS DEPICT THE UPPER LEVEL SHORTWAVE LIFTING
NORTHEASTWARD THIS MORNING SUCH THAT THE STRONGER FORCING REMAINS
NORTH OF THE CANADIAN BORDER AFTER DAYBREAK. HOWEVER THIS AFTERNOON
THE SHORTWAVE GAINS STRENGTH AND DEVELOPS SOUTHWARD ACROSS
WESTERN/CENTRAL NORTH DAKOTA...MOVING EAST INTO THE RED RIVER VALLEY
LATE THIS EVENING. IN RESPONSE...THE SURFACE FRONT IS FORECAST TO
MOVE INTO WESTERN NORTH DAKOTA LATE THIS AFTERNOON AND PROGRESS
EASTWARD SLOWLY...BEFORE STALLING OVER CENTRAL NORTH DAKOTA.
FORECAST CAPE VALUES OF 1000 TO OVER 2000 ARE FORECAST OVER WESTERN
AND CENTRAL NORTH DAKOTA THIS AFTERNOON...COMBINED WITH 0-6KM BULK
SHEAR VALUES OF 35 TO 50 KNOTS. THE LARGE AMOUNT OF AVAILABLE
CONVECTIVE ENERGY...ALONG WITH THE STRONG SHEAR...SUGGESTS
THUNDERSTORMS COULD REACH SEVERE LIMITS. THUS THE STORM PREDICTION
CENTER HAS PLACED MOST OF THE FORECAST AREA IS IN A SLIGHT RISK OF
SEVERE THUNDERSTORMS FOR THIS AFTERNOON AND TONIGHT.
ANOTHER VERY WARM DAY TODAY WITH HIGHS PROGGED TO BE IN THE MID TO
UPPER 80S FROM THE NORTH THROUGH THE JAMES RIVER VALLEY...AND INTO
THE LOWER 90S ALONG AND SOUTH/WEST OF THE MISSOURI RIVER. LOWS
TONIGHT IN THE 60S.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 335 AM CDT FRI AUG 30 2013
ON SATURDAY...THUNDERSTORMS ARE EXPECTED TO LINGER...ESPECIALLY
SOUTHEAST IN THE VICINITY OF A COLD FRONT. THE EXTREME SOUTHEAST
WILL LIKELY BE ON THE FRINGE OF THE MOST FAVORABLE AREA FOR
ISOLATED SEVERE STORMS. DRIER AIR WILL PUSH INTO THE
SOUTHWEST...DROPPING DEWPOINTS INTO THE 40S AND MINIMUM AFTERNOON
RH BETWEEN 25-30 PERCENT. THE GRASSLAND FIRE DANGER INDEX IS
FORECAST TO BE IN THE HIGH CATEGORY. THE CHANCE OF ADDITIONAL RAIN
BEYOND SATURDAY IS LOW. SUNDAY WILL LIKELY BE THE COOLEST DAY OF
THE WEEK...WITH HIGHS MAINLY IN THE 70S. A WARMING TREND WILL
BEGIN ON LABOR DAY...WITH HIGHS FROM THE UPPER 70S EAST TO MID 80S WEST.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 182 SATURDAY)
ISSUED AT 1021 AM CDT FRI AUG 30 2013
VFR CONDITIONS OUTSIDE OF THUNDERSTORMS ARE EXPECTED FOR THE
UPCOMING 18 UTC TAFS. SCATTERED THUNDERSTORMS ARE EXPECTED TO
INITIATE BETWEEN THE WESTERN TAF SITES OF KISN/KDIK AND THE
CENTRAL SITES OF KMOT/KBIS BETWEEN 20-22 UTC...AND MOVE EAST
THROUGH THE EVENING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
918 AM CDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 917 AM CDT FRI AUG 30 2013
VISIBILITIES OUTSIDE OF THE CENTRAL AND NORTHERN RED RIVER VALLEY
HAVE BEGUN TO RAPIDLY INCREASE. I WILL EXTEND THE DENSE FOG
ADVISORY FROM HILLSBORO NORTH TO THE CANADIAN BORDER AND ALLOW
OTHER COUNTIES TO EXPIRE AT 9 AM CDT. WILL NEED TO FINE TUNE SKY
AND TEMP TRENDS PRIOR TO ANOTHER GRID/ZONE FORECAST AT 10 AM CDT.
UPDATE ISSUED AT 710 AM CDT FRI AUG 30 2013
VSBY AT THE OBSERVATION SITE IN VALLEY CITY AND FARGO HAS DROPPED
TO 1/4SM...AS WELL AS JAMESTOWN. WILL ADD THIS AREA TO THE DENSE
FOG ADVISORY.
UPDATE ISSUED AT 635 AM CDT FRI AUG 30 2013
OTHER THAN THE FOG...SKY WILL BE A CHALLENGE THIS MORNING. LOW
STRATUS HAS DEVELOPED OR MOVED INTO THE EASTERN FA. 09Z RAP
GUIDANCE SUGGESTS THAT THESE CIGS WILL BREAK APART RATHER QUICKLY
THIS MORNING. MUCH OF THIS IS LIKELY THIN...SO WILL GO WITH THIS
THINKING. UPDATED THE SKY GRIDS ACCORDINGLY. IF THIS THINKING IS
CORRECT THAN MAX TEMPS WILL NOT BE AFFECTED.
UPDATE ISSUED AT 606 AM CDT FRI AUG 30 2013
ISSUED A DENSE FOG ADVISORY FOR A FEW HOURS THIS MORNING. THE FOG
IS REALLY THICK LOCALLY AT THE OFFICE...AND JUDGING FROM
OBSERVATIONS SIMILAR CONDITIONS LIKELY EXIST ELSEWHERE ACROSS THE
NORTHERN FA. COVERAGE MAY BE MORE AREAS THAN WIDESPREAD...BUT
STILL A GOOD IDEA TO HEIGHTEN AWARENESS.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 343 AM CDT FRI AUG 30 2013
THE MAIN CHALLENGE WILL BE THUNDER AND SEVERE POTENTIAL TONIGHT
AND SATURDAY. TEMPERATURES WILL REMAIN ABOVE NORMAL VALUES...BUT
NOT QUITE AS WARM AS PREVIOUS DAYS.
LOW LEVEL RIDGING WILL MOVE ACROSS THE REGION TODAY. THERE WILL BE
PATCHY DENSE FOG THIS MORNING FOR LOCATIONS THAT RECEIVED RAINFALL
YESTERDAY...AND WILL NEED TO MONITOR EXTEND FOR POSSIBLE ADVISORY.
WATER VAPOR IMAGERY INDICATES A COUPLE SHORTWAVES UPSTREAM. THE
STRONGEST WAVE IS JUST NOW CRASHING ONSHORE ACROSS THE PACIFIC
NW...AND WILL TRACK NEAR THE INTERNATIONAL BORDER...PASSING THIS
REGION ON SATURDAY. THE NAM IS SLIGHTLY SLOWER THAN THE
GEM/GFS/ECMWF...BUT HAS A SIMILAR IDEA. THERE WILL BE STORMS THIS
AFTERNOON ACROSS WESTERN/CENTRAL NORTH DAKOTA WITHIN AN AXIS OF
MOISTURE AHEAD OF A LOW LEVEL TROUGH. THIS FEATURE WILL MOVE INTO
THE FA TONIGHT. ALTHOUGH THUNDERSTORMS ARE EXPECTED...INSTABILITY
SHOULD WEAKEN ENOUGH THAT THE POTENTIAL FOR SEVERE STORMS WILL BE
LIMITED (INSTABILITY IS MUCH WEAKER THAN LAST NIGHT). WOULD NOT BE
SURPRISED TO SEE SOME STRONGER STORMS ENTER THE DEVILS LAKE BASIN
LATER THIS EVENING...AND WEAKEN AS THEY MOVE INTO THE VALLEY. THE
MAIN COLD FRONT WILL MOVE THROUGH ON SATURDAY...WITH THUNDERSTORMS
AGAIN POSSIBLE. STILL NOT EXACTLY SURE ABOUT TIMING...AND
INSTABILITY VALUES AHEAD OF THIS FEATURE. THESE TWO FACTORS WILL
HAVE THE MOST INFLUENCE ON SEVERE POTENTIAL AS DEEP LAYER SHEAR
WILL BE STRONG (FAVORABLE FOR SEVERE STORMS).
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 343 AM CDT FRI AUG 30 2013
SATURDAY NIGHT-SUNDAY NIGHT...REGION WILL BE WITHIN A COOLER
AIRMASS FOLLOWING THE PASSAGE OF THE COLD FRONT. SURFACE HIGH
PRESSURE WILL MOVE ACROSS THE REGION. ANTICIPATE DRY WEATHER
(EXCEPT FOR A PORTION OF NW MN WHICH MAY BE WITHIN THE TRACK OF
ANOTHER SHORTWAVE WITHIN THE NW FLOW ALOFT) WITH TEMPERATURES
NEAR OR EVEN SLIGHTLY BELOW NORMAL VALUES.
MONDAY-THURSDAY...00 UTC GFS/ECMWF SHOW 500 HPA RIDGE AXIS MAINLY
ACROSS EASTERN MT AND THE WESTERN DAKOTAS...KEEPING THE FORECAST
AREA IN NORTHWEST FLOW ALOFT. MODELS DIFFER GREATLY WITH A
CANADIAN TROUGH MID-WEEK WITH THE ECMWF MUCH DEEPER ACROSS THE
GREAT LAKES COMPARED TO THE GFS. WITH THE GFS/S TROUGH POSITION
FARTHER NORTH...THERE IS A NORTHWARD SURGE OF MOISTURE INTO THE
NORTHERN PLAINS ON WEDNESDAY. FOR THIS...ALLBLEND GUIDANCE ADDED
SPORADIC 20 POPS ACROSS THE FORECAST AREA. WILL REMOVE ALL POPS
FOR NOW GIVEN THE PREVIOUS DRY FORECAST...THE CURRENT PROLONGED
DRY-SPELL AND MODEL VARIANCE. BEING ON THE COOLER SIDE OF THE
THERMAL AXIS...HIGH TEMPERATURES SHOULD RANGE FROM THE 70S TO
LOWER 80S AND NIGHTTIME LOWS FROM THE MID 50S TO LOWER 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 635 AM CDT FRI AUG 30 2013
DENSE FOG AROUND THE REGION WILL DISSIPATE BY MID-MORNING. IN
ADDITION...THERE ARE LOW CIGS ALONG AND EAST OF THE RED RIVER
VALLEY. 09Z RAP GUIDANCE SUGGESTS THAT THESE CIGS WILL DISSIPATE
BY 15Z. WILL GO WITH THIS THINKING...BUT MONITOR AND AMEND IF
NEEDED.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR NDZ008-016-
027-030.
MN...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR MNZ001-002-
004-007.
&&
$$
UPDATE...SPEICHER
SHORT TERM...TG
LONG TERM...TG/ROGERS
AVIATION...TG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
710 AM CDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 710 AM CDT FRI AUG 30 2013
VSBY AT THE OBSERVATION SITE IN VALLEY CITY AND FARGO HAS DROPPED
TO 1/4SM...AS WELL AS JAMESTOWN. WILL ADD THIS AREA TO THE DENSE
FOG ADVISORY.
UPDATE ISSUED AT 635 AM CDT FRI AUG 30 2013
OTHER THAN THE FOG...SKY WILL BE A CHALLENGE THIS MORNING. LOW
STRATUS HAS DEVELOPED OR MOVED INTO THE EASTERN FA. 09Z RAP
GUIDANCE SUGGESTS THAT THESE CIGS WILL BREAK APART RATHER QUICKLY
THIS MORNING. MUCH OF THIS IS LIKELY THIN...SO WILL GO WITH THIS
THINKING. UPDATED THE SKY GRIDS ACCORDINGLY. IF THIS THINKING IS
CORRECT THAN MAX TEMPS WILL NOT BE AFFECTED.
UPDATE ISSUED AT 606 AM CDT FRI AUG 30 2013
ISSUED A DENSE FOG ADVISORY FOR A FEW HOURS THIS MORNING. THE FOG
IS REALLY THICK LOCALLY AT THE OFFICE...AND JUDGING FROM
OBSERVATIONS SIMILAR CONDITIONS LIKELY EXIST ELSEWHERE ACROSS THE
NORTHERN FA. COVERAGE MAY BE MORE AREAS THAN WIDESPREAD...BUT
STILL A GOOD IDEA TO HEIGHTEN AWARENESS.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 343 AM CDT FRI AUG 30 2013
THE MAIN CHALLENGE WILL BE THUNDER AND SEVERE POTENTIAL TONIGHT
AND SATURDAY. TEMPERATURES WILL REMAIN ABOVE NORMAL VALUES...BUT
NOT QUITE AS WARM AS PREVIOUS DAYS.
LOW LEVEL RIDGING WILL MOVE ACROSS THE REGION TODAY. THERE WILL BE
PATCHY DENSE FOG THIS MORNING FOR LOCATIONS THAT RECEIVED RAINFALL
YESTERDAY...AND WILL NEED TO MONITOR EXTEND FOR POSSIBLE ADVISORY.
WATER VAPOR IMAGERY INDICATES A COUPLE SHORTWAVES UPSTREAM. THE
STRONGEST WAVE IS JUST NOW CRASHING ONSHORE ACROSS THE PACIFIC
NW...AND WILL TRACK NEAR THE INTERNATIONAL BORDER...PASSING THIS
REGION ON SATURDAY. THE NAM IS SLIGHTLY SLOWER THAN THE
GEM/GFS/ECMWF...BUT HAS A SIMILAR IDEA. THERE WILL BE STORMS THIS
AFTERNOON ACROSS WESTERN/CENTRAL NORTH DAKOTA WITHIN AN AXIS OF
MOISTURE AHEAD OF A LOW LEVEL TROUGH. THIS FEATURE WILL MOVE INTO
THE FA TONIGHT. ALTHOUGH THUNDERSTORMS ARE EXPECTED...INSTABILITY
SHOULD WEAKEN ENOUGH THAT THE POTENTIAL FOR SEVERE STORMS WILL BE
LIMITED (INSTABILITY IS MUCH WEAKER THAN LAST NIGHT). WOULD NOT BE
SURPRISED TO SEE SOME STRONGER STORMS ENTER THE DEVILS LAKE BASIN
LATER THIS EVENING...AND WEAKEN AS THEY MOVE INTO THE VALLEY. THE
MAIN COLD FRONT WILL MOVE THROUGH ON SATURDAY...WITH THUNDERSTORMS
AGAIN POSSIBLE. STILL NOT EXACTLY SURE ABOUT TIMING...AND
INSTABILITY VALUES AHEAD OF THIS FEATURE. THESE TWO FACTORS WILL
HAVE THE MOST INFLUENCE ON SEVERE POTENTIAL AS DEEP LAYER SHEAR
WILL BE STRONG (FAVORABLE FOR SEVERE STORMS).
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 343 AM CDT FRI AUG 30 2013
SATURDAY NIGHT-SUNDAY NIGHT...REGION WILL BE WITHIN A COOLER
AIRMASS FOLLOWING THE PASSAGE OF THE COLD FRONT. SURFACE HIGH
PRESSURE WILL MOVE ACROSS THE REGION. ANTICIPATE DRY WEATHER
(EXCEPT FOR A PORTION OF NW MN WHICH MAY BE WITHIN THE TRACK OF
ANOTHER SHORTWAVE WITHIN THE NW FLOW ALOFT) WITH TEMPERATURES
NEAR OR EVEN SLIGHTLY BELOW NORMAL VALUES.
MONDAY-THURSDAY...00 UTC GFS/ECMWF SHOW 500 HPA RIDGE AXIS MAINLY
ACROSS EASTERN MT AND THE WESTERN DAKOTAS...KEEPING THE FORECAST
AREA IN NORTHWEST FLOW ALOFT. MODELS DIFFER GREATLY WITH A
CANADIAN TROUGH MID-WEEK WITH THE ECMWF MUCH DEEPER ACROSS THE
GREAT LAKES COMPARED TO THE GFS. WITH THE GFS/S TROUGH POSITION
FARTHER NORTH...THERE IS A NORTHWARD SURGE OF MOISTURE INTO THE
NORTHERN PLAINS ON WEDNESDAY. FOR THIS...ALLBLEND GUIDANCE ADDED
SPORADIC 20 POPS ACROSS THE FORECAST AREA. WILL REMOVE ALL POPS
FOR NOW GIVEN THE PREVIOUS DRY FORECAST...THE CURRENT PROLONGED
DRY-SPELL AND MODEL VARIANCE. BEING ON THE COOLER SIDE OF THE
THERMAL AXIS...HIGH TEMPERATURES SHOULD RANGE FROM THE 70S TO
LOWER 80S AND NIGHTTIME LOWS FROM THE MID 50S TO LOWER 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 635 AM CDT FRI AUG 30 2013
DENSE FOG AROUND THE REGION WILL DISSIPATE BY MID-MORNING. IN
ADDITION...THERE ARE LOW CIGS ALONG AND EAST OF THE RED RIVER
VALLEY. 09Z RAP GUIDANCE SUGGESTS THAT THESE CIGS WILL DISSIPATE
BY 15Z. WILL GO WITH THIS THINKING...BUT MONITOR AND AMEND IF
NEEDED.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR NDZ006>008-
014>016-024-026>030-038-039-054.
MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR MNZ001>009-
013>016.
&&
$$
UPDATE...TG
SHORT TERM...TG
LONG TERM...TG/ROGERS
AVIATION...TG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
635 AM CDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 635 AM CDT FRI AUG 30 2013
OTHER THAN THE FOG...SKY WILL BE A CHALLENGE THIS MORNING. LOW
STRATUS HAS DEVELOPED OR MOVED INTO THE EASTERN FA. 09Z RAP
GUIDANCE SUGGESTS THAT THESE CIGS WILL BREAK APART RATHER QUICKLY
THIS MORNING. MUCH OF THIS IS LIKELY THIN...SO WILL GO WITH THIS
THINKING. UPDATED THE SKY GRIDS ACCORDINGLY. IF THIS THINKING IS
CORRECT THAN MAX TEMPS WILL NOT BE AFFECTED.
UPDATE ISSUED AT 606 AM CDT FRI AUG 30 2013
ISSUED A DENSE FOG ADVISORY FOR A FEW HOURS THIS MORNING. THE FOG
IS REALLY THICK LOCALLY AT THE OFFICE...AND JUDGING FROM
OBSERVATIONS SIMILAR CONDITIONS LIKELY EXIST ELSEWHERE ACROSS THE
NORTHERN FA. COVERAGE MAY BE MORE AREAS THAN WIDESPREAD...BUT
STILL A GOOD IDEA TO HEIGHTEN AWARENESS.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 343 AM CDT FRI AUG 30 2013
THE MAIN CHALLENGE WILL BE THUNDER AND SEVERE POTENTIAL TONIGHT
AND SATURDAY. TEMPERATURES WILL REMAIN ABOVE NORMAL VALUES...BUT
NOT QUITE AS WARM AS PREVIOUS DAYS.
LOW LEVEL RIDGING WILL MOVE ACROSS THE REGION TODAY. THERE WILL BE
PATCHY DENSE FOG THIS MORNING FOR LOCATIONS THAT RECEIVED RAINFALL
YESTERDAY...AND WILL NEED TO MONITOR EXTEND FOR POSSIBLE ADVISORY.
WATER VAPOR IMAGERY INDICATES A COUPLE SHORTWAVES UPSTREAM. THE
STRONGEST WAVE IS JUST NOW CRASHING ONSHORE ACROSS THE PACIFIC
NW...AND WILL TRACK NEAR THE INTERNATIONAL BORDER...PASSING THIS
REGION ON SATURDAY. THE NAM IS SLIGHTLY SLOWER THAN THE
GEM/GFS/ECMWF...BUT HAS A SIMILAR IDEA. THERE WILL BE STORMS THIS
AFTERNOON ACROSS WESTERN/CENTRAL NORTH DAKOTA WITHIN AN AXIS OF
MOISTURE AHEAD OF A LOW LEVEL TROUGH. THIS FEATURE WILL MOVE INTO
THE FA TONIGHT. ALTHOUGH THUNDERSTORMS ARE EXPECTED...INSTABILITY
SHOULD WEAKEN ENOUGH THAT THE POTENTIAL FOR SEVERE STORMS WILL BE
LIMITED (INSTABILITY IS MUCH WEAKER THAN LAST NIGHT). WOULD NOT BE
SURPRISED TO SEE SOME STRONGER STORMS ENTER THE DEVILS LAKE BASIN
LATER THIS EVENING...AND WEAKEN AS THEY MOVE INTO THE VALLEY. THE
MAIN COLD FRONT WILL MOVE THROUGH ON SATURDAY...WITH THUNDERSTORMS
AGAIN POSSIBLE. STILL NOT EXACTLY SURE ABOUT TIMING...AND
INSTABILITY VALUES AHEAD OF THIS FEATURE. THESE TWO FACTORS WILL
HAVE THE MOST INFLUENCE ON SEVERE POTENTIAL AS DEEP LAYER SHEAR
WILL BE STRONG (FAVORABLE FOR SEVERE STORMS).
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 343 AM CDT FRI AUG 30 2013
SATURDAY NIGHT-SUNDAY NIGHT...REGION WILL BE WITHIN A COOLER
AIRMASS FOLLOWING THE PASSAGE OF THE COLD FRONT. SURFACE HIGH
PRESSURE WILL MOVE ACROSS THE REGION. ANTICIPATE DRY WEATHER
(EXCEPT FOR A PORTION OF NW MN WHICH MAY BE WITHIN THE TRACK OF
ANOTHER SHORTWAVE WITHIN THE NW FLOW ALOFT) WITH TEMPERATURES
NEAR OR EVEN SLIGHTLY BELOW NORMAL VALUES.
MONDAY-THURSDAY...00 UTC GFS/ECMWF SHOW 500 HPA RIDGE AXIS MAINLY
ACROSS EASTERN MT AND THE WESTERN DAKOTAS...KEEPING THE FORECAST
AREA IN NORTHWEST FLOW ALOFT. MODELS DIFFER GREATLY WITH A
CANADIAN TROUGH MID-WEEK WITH THE ECMWF MUCH DEEPER ACROSS THE
GREAT LAKES COMPARED TO THE GFS. WITH THE GFS/S TROUGH POSITION
FARTHER NORTH...THERE IS A NORTHWARD SURGE OF MOISTURE INTO THE
NORTHERN PLAINS ON WEDNESDAY. FOR THIS...ALLBLEND GUIDANCE ADDED
SPORADIC 20 POPS ACROSS THE FORECAST AREA. WILL REMOVE ALL POPS
FOR NOW GIVEN THE PREVIOUS DRY FORECAST...THE CURRENT PROLONGED
DRY-SPELL AND MODEL VARIANCE. BEING ON THE COOLER SIDE OF THE
THERMAL AXIS...HIGH TEMPERATURES SHOULD RANGE FROM THE 70S TO
LOWER 80S AND NIGHTTIME LOWS FROM THE MID 50S TO LOWER 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 635 AM CDT FRI AUG 30 2013
DENSE FOG AROUND THE REGION WILL DISSIPATE BY MID-MORNING. IN
ADDITION...THERE ARE LOW CIGS ALONG AND EAST OF THE RED RIVER
VALLEY. 09Z RAP GUIDANCE SUGGESTS THAT THESE CIGS WILL DISSIPATE
BY 15Z. WILL GO WITH THIS THINKING...BUT MONITOR AND AMEND IF
NEEDED.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR NDZ006>008-
014>016-024-026>030-054.
MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR MNZ001-
004>009-013>016.
&&
$$
UPDATE...TG
SHORT TERM...TG
LONG TERM...TG/ROGERS
AVIATION...TG
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
658 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST
EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND
WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE
NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE
RETURNS ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
630 AM UPDATE...REGARDING PRECIP IN THE SAVANNAH RIVER VALLEY...THE
CURRENT TRENDS SUGGEST THE ACTIVITY WILL DIMINISH AS INSTABILITY
BOTTOMS OUT AT DIURNAL MINIMUM. HOWEVER RAP CAPE TRENDS BEGIN
RAMPING BACK UP OVER THE NEXT COUPLE HOURS. LAPSE RATES AND PROG
SOUNDINGS STILL LOOK UNIMPRESSIVE TODAY AWAY FROM THE BLUE
RIDGE...BUT THESE CELLS ARE IN AN AREA FAVORED BY THE OVERNIGHT NAM
RUNS AS WELL AS THE RAP SO I HAVE MADE A GRADUAL TRANSITION OF POPS
FROM THE WRN UPSTATE UP TO THE MTNS.
AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION
WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL
LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE
REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK
OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE
RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY
CORRESPONDINGLY GREATER.
UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER
THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS
THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO
MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW
CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS
CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST
CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER
THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 225 AM FRI...THE CWFA WILL REMAIN IN A WEAKNESS BETWEEN THE
RIDGING OVER THE CENTRAL CONUS AND THE ATLANTIC. THIS ALLOWS WEAK
SHORT WAVES MOVING THRU THE WESTERLIES TO DIG A SHALLOW TROF OVER
THE ERN CONUS EARLY IN THE PERIOD AND A STRONGER TROF BY MONDAY AS
AN UPPER LOW MOVES INTO THE GREAT LAKES REGION. WEAK S TO SWLY LOW
LEVEL FLOW KEEPS COPIOUS MOISTURE OVER THE AREA WITH PW VALUES AS
HIGH AS 2 INCHES. THIS COMBINED WITH MODERATE INSTABILITY WILL LEAD
TO DIURNAL CONVECTION BOTH SAT AND SUN AFTERNOONS. COVERAGE BOTH
DAYS WILL FAVOR THE MTNS WITH LOWER...BUT STILL SCT...CHC OVER THE
PIEDMONT. HIGHS WILL BE NEARLY STEADY NEAR NORMAL BOTH DAYS WITH
LOWS NEARLY STEADY ABOUT 5 DEGREES ABOVE NORMAL.
A WEAK FRONT MOVES IN WITH THE STRONGER TROF ON MON. EVEN WITH THE
FRONT AND TROF...CONVECTIVE COVERAGE WILL FAVOR THE MTNS AND TAPER
OFF TO THE PIEDMONT. HIGHS WILL BE NEAR TO SLIGHTLY ABOVE NORMAL.
WITH COPIOUS MOISTURE AND SLOW MOVING STORMS...HEAVY RAINFALL IS
POSSIBLE...POTENTIALLY LEADING TO ISOLATED FLASH FLOODING EACH DAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 310 AM FRI...AN UPPER TROF STARTS OUT OVER THE ERN CONUS ON
TUE THEN SLIDES OFF SHORE WED. THE CWFA REMAINS IN LIGHT NWLY FLOW
THRU THE END OF THE PERIOD WITH LITTLE IN THE WAY OF SHORT WAVE
ACTIVITY DROPPING THRU THE FLOW. AT THE SFC...A COLD FRONT STARTS
OUT OVER THE AREA TUE THEN SLIDES SOUTH AND EAST OF THE AREA WED AS
HIGH PRESSURE BUILDS IN FROM THE NW THU. ALL THIS LEADS TO DIURNAL
SCT CONVECTION TUE. THERE IS SOME INDICATION THAT MOISTURE COULD
LINGER OVER THE SAV RIVER VALLEY OR SWRN NC MTNS ON WED WITH DRIER
AIR MOVING IN ELSEWHERE. HOWEVER...HAVE KEPT FCST DRY FOR NOW. DRY
FCST CONTINUES THU. TEMPERATURES FALL BELOW NORMAL WITH COOLER HIGH
PRESSURE MOVING IN.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AT KCLT...SOME UNCERTAINTY AS TO WHETHER LOW MVFR STRATOCU WILL
REACH THE FIELD IN EASTERLY FLOW INTO THE PIEDMONT EARLY THIS
MORNING. WILL MAINTAIN SCT010 FOR FIRST HOUR. OTHERWISE VFR CUMULUS
WILL BE THE DOMINANT CLOUDS BY MID MORNING. LIGHT ENE WINDS SHOULD
VEER TO SE BY AFTN PER CONSENSUS OF LATEST GUIDANCE. THE SELY FLOW
WITH ATLANTIC FETCH MAY CAUSE LOW STRATUS TO MOVE IN TONIGHT SIMILAR
TO WHAT IS HAPPENING THIS MORNING. GUIDANCE HAS HANDLED THIS
MORNING/S CIGS POORLY SO WILL KEEP TONIGHT VFR FOR NOW.
ELSEWHERE...PATCHY STRATOCU WILL PLAGUE THE TAF SITES EARLY THIS
MORNING. THE CLOUDS ARE MOSTLY LOW VFR TO MVFR BUT OBS SUGGEST SOME
BASES MAY BE AT IFR LEVEL. SHRA IN THE SAVANNAH RIVER VALLEY WILL
CAUSE EVEN MORE RESTRICTIVE CONDITIONS EARLY TODAY AS WELL. AWAY
FROM PRECIP CIGS SHOULD EASILY BE ABLE TO MIX UP TO VFR BY MID
MORNING. ISOLD TO WIDELY SCT CONVECTION MAY DEVELOP BY MIDDAY NEAR
THE BLUE RIDGE BUT CHCS TOO LOW FOR A TAF MENTION ATTM. LIGHT NE TO
ENE WINDS WILL VEER TO GENERALLY SE BY AFTERNOON AND REMAIN THERE
INTO THE EVENING. THE SE WINDS WILL BRING IN ATLANTIC MOISTURE AND
MAY ALLOW CIGS TO LOWER ONCE AGAIN TONIGHT...WITH GUIDANCE ALSO
SUPPORTING MVFR FOG ACRS MUCH OF THE AREA.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY
THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN
VALLEYS AND WHERE RAIN FELL THE DAY BEFORE.
CONFIDENCE TABLE...
11-17Z 17-23Z 23-05Z 05-11Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 97%
KGSP HIGH 84% HIGH 100% HIGH 100% HIGH 94%
KAVL HIGH 90% HIGH 98% HIGH 100% HIGH 86%
KHKY HIGH 85% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 81% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 87% HIGH 100% HIGH 100% HIGH 90%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...WIMBERLEY
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1126 AM MDT FRI AUG 30 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 453 AM MDT FRI AUG 30 2013
CURRENT WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS INDICATING LARGE
UPPER HIGH REMAINING IN PLACE ACROSS THE HIGH PLAINS THROUGH THE
ROCKIES WITH FASTER ZONAL FLOW NOTED ACROSS THE NORTHERN TIER OF
STATES AT THIS TIME. WATER VAPOR IMAGERY AND SATELLITE DATA
INDICATING AN INCREASE IN ATMOSPHERIC MOISTURE ACROSS SOUTH CENTRAL
AND SOUTHEAST COLORADO ALONG WITH AN EMBEDDED SHORT WAVE TRANSLATING
ACROSS THE NORTHERN GREAT BASIN AT THIS TIME. WARM AIR ALOFT ALSO
REMAINS IN PLACE UNDERNEATH THE UPPER HIGH WITH CURRENT TEMPS IN THE
MID 40S TO MID 50S ACROSS THE HIGHER TERRAIN AND 60S TO LOWER 70S
ACROSS THE LOWER ELEVATIONS AT THIS TIME.
TODAY AND TONIGHT...WITH A TAD MORE MOISTURE IN PLACE...ALONG WITH
TAIL END OF NORTHERN GREAT BASIN SHORT WAVE TRANSLATING ACROSS THE
NORTHERN PORTIONS OF THE STATE THIS AFTERNOON...SHOULD SEE AN
UPSWING IN CONVECTION OVER AND NEAR THE HIGH TERRAIN THIS AFTERNOON
AND EARLY EVENING...WITH BEST COVERAGE EXPECTED ACROSS THE CENTRAL
MTS. HAVE ALSO INCREASED POPS ACROSS TELLER COUNTY AND THE PALMER
DVD LATE THIS AFTERNOON AND EVENING WITH LATEST RUNS OF THE HIGHER
RESOLUTION HRRR AND RAP MODELS COMING MORE IN LINE WITH THE MORE
AGGRESSIVE NAM. AT ANY RATE...MODEL SOUNDINGS STILL INDICATING
CONVECTION TO BE RATHER HIGH BASED ACROSS THE EASTERN MTS WITH NOT
MUCH MEASURABLE PRECIPITATION EXPECTED. TEMPS AGAIN TO WARM RATHER
QUICKLY THIS MORNING...THOUGH WITH MORE CONVECTIVE CLOUD
COVER...SHOULD SEE HIGHS NEAR OR ONLY SLIGHTLY COOLER THAN
YESTERDAYS READINGS. COULD SEE NEAR RECORD HIGHS AT ALS (86F IN
2012) AND COS (94F IN 1990) ONCE AGAIN TODAY...THOUGH CURRENT RECORD
AT PUB OF 102F IN 1990 LOOKS SAFE.
CONVECTIVE DIMINISHES THROUGH THE EVENING WITH DEBRIS CLOUDS SLOWLY
DIMINISHING THROUGH THE OVERNIGHT...KEEPING LOWS GENERALLY ABOVE
SEASONAL AVERAGES.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 402 AM MDT FRI AUG 30 2013
...CHANCE FOR THUNDERSTORMS WITH LOCALLY HEAVY RAIN RETURNING TO
MOST AREAS THIS WEEKEND...
MODELS INDICATING THAT A SHORTWAVE AND LOW LEVEL FRONTAL SYSTEM WILL
DROP SOUTHEAST THROUGH THE CENTRAL PLAINS SATURDAY AFTERNOON AND
EVENING...RESULTING IN LOW LEVEL UPSLOPE ON THE PLAINS...AND TAPPING
MONSOON MOISTURE ALOFT. THE INTERACTION OF THE 2 WILL RESULT IN
FAIRLY WIDESPREAD CHANCES FOR SHOWERS AND THUNDERSTORMS DEVELOPING
ACROSS THE AREA SATURDAY AFTERNOON AND EVENING...WITH ENOUGH MOISTURE
PRESENT TO PRODUCE LOCALLY HEAVY RAINFALL. SO...THE THREAT OF
FLOODING WILL RAMP UP ONCE AGAIN FOR AREA BURN SCARS...AS WELL AS
FOR OTHER AREAS...AWAY FROM THE BURN SCARS. OTHER POSSIBLE THREATS
WILL INCLUDE LIGHTNING...GUSTY WINDS AND SMALL HAIL.
ELEVATED CHANCES FOR RAIN AND FLASH FLOODING WILL PROBABLY CONTINUE
FOR A LOT OF AREAS AT LEAST THROUGH SUNDAY. THERE ARE MIXED SIGNALS
FOR WHAT TO EXPECT ACROSS THE PLAINS ON SUNDAY. SOME MODEL RUNS
SHOW FAIRLY WIDESPREAD SHOWERS AND HEAVY RAIN POTENTIAL ACROSS THE
PLAINS ON SUNDAY...WHILE OTHERS HOLD ALL THE SHOWERS AND HEAVY RAIN
POTENTIAL BACK OVER THE MOUNTAINS AND HIGH VALLEYS. SO...IT SEEMS
PRETTY CLEAR THE MOUNTAINS AND HIGH VALLEYS WILL HAVE ANOTHER
ACTIVE DAY...BUT IT IS LESS CLEAR EXACTLY WHAT WILL HAPPEN ON THE
PLAINS. FOR NOW...FORECASTS ARE SORT OF SPLITTING THE DIFFERENCE...
KEEPING THE COVERAGE OF STORMS SOMEWHERE IN THE MIDDLE...GENERALLY
IN THE SCATTERED CATEGORY. IN ANY EVENT...WHATEVER STORMS MANAGE
TO FORM WILL ALSO HAVE THE POTENTIAL FOR LOCALLY HEAVY RAIN...SO
THE THREAT TO AREA BURN SCARS WILL REMAIN HIGH ON SUNDAY.
NEXT WEEK...IT APPEARS UPPER HIGH PRESSURE WILL REORGANIZE AND
RECENTER OVER EASTERN COLORADO. THIS WILL PROBABLY RESULT IN
CONTINUED MONSOON CONVECTION OVER THE MOUNTAINS...BUT WITH
DRIER AND WARMER CONDITIONS AGAIN OVER MOST OF THE PLAINS.
SOME ACTIVITY COULD CREEP EAST ACROSS THE PLAINS AT TIMES...
BUT THE BULK OF THE ACTIVITY WILL PROBABLY REMAIN OVER THE
HIGH COUNTRY. THIS MEANS THAT THE WATCH FOR FLASH FLOODING
ON AND NEAR AREA BURN SCARS WILL CONTINUE NEXT WEEK AS ALL
OF THE BURN SCARS WILL LIKELY REMAIN UNDER THE MONSOON
PLUME. LW
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1000 AM MDT FRI AUG 30 2013
VFR CONDITIONS EXPECTED AT THE TAF SITES TODAY WITH ISOLATED
THUNDERSTORMS EXPECTED TO DEVELOP OVER THE MOUNTAINS AROUND 17Z.
KALS HAS THE BEST CHANCE FOR SEEING VCTS...HOWEVER THERE IS SOME
CHANCE THAT KCOS COULD AS WELL. WILL CARRY VCTS IN KALS TAF FOR
NOW AND MONITOR LATEST RADAR TRENDS FOR POSSIBLE INCLUSION IN
KCOS. GUSTY ERRATIC WINDS WILL BE THE MAIN THREATS WITH
THUNDERSTORMS ALONG WITH LIGHTNING. SOME BRIEF MODERATE TO HEAVY
RAINFALL WILL BE POSSIBLE WITH STORMS ALONG THE CONTINENTAL DIVIDE
THIS AFTERNOON AND EVENING. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MW
LONG TERM...LW
AVIATION...KT
AREA FORECAST DISCUSSION
NWS MIAMI FL
141 PM EDT FRI AUG 30 2013
.AVIATION...
A WEAK UPPER LOW COMBINED WITH DAYTIME HEATING AND SEA BREEZES
WILL MAINTAIN A SLIGHT CHANCE FOR SHOWERS AND STORMS ACROSS THE
LOCAL AREA THROUGH THE EVENING HOURS TODAY. THE LATEST HRRR MODEL
RUN INDICATES THE BULK OF THIS ACTIVITY REMAINING INLAND OF THE
TAF SITES THROUGH THIS TIME. CONDITIONS SHOULD TREND DOWN THROUGH
OVERNIGHT HOURS WITH THE BEST RAIN CHANCES REMAINING OVER THE
ADJACENT MARINE AREAS THROUGH SATURDAY MORNING. WINDS WILL BECOME
CALM OVERNIGHT ACROSS THE AREA. SIMILAR CONDITIONS ARE ANTICIPATED
SATURDAY WITH ONSHORE WINDS THROUGH THE LATE MORNING AND AFTERNOON
PERIODS. THE BEST RAIN CHANCES WILL REMAIN INLAND OF THE SITES.
&&
.PREV DISCUSSION... /ISSUED 932 AM EDT FRI AUG 30 2013/
UPDATE...A MID-UPPER LEVEL LOW CONTINUES OVER SOUTH FL AS SEEN IN
WATER VAPOR IMAGERY. A COMPLEX OF THUNDERSTORMS IS OCCURRING OVER
THE FLORIDA STRAITS...DRIVEN BY A VORT LOBE TRAVERSING THE
SOUTHERN SIDE OF THIS UPPER LEVEL LOW. THIS VORT WILL MOVE NE
AND ACROSS THE BAHAMAS TODAY, KEEPING ORGANIZED CONVECTION TO OUR
EAST. HOWEVER, LATEST RADAR IMAGERY SHOWS AN OUTFLOW BOUNDARY
ORIGINATING FROM THIS CONVECTION MOVING NORTH AT 25 KNOTS...NOW
LOCATED EAST OF THE MIDDLE TO UPPER KEYS. THIS COULD BRING A BRIEF
PERIOD OF RAIN TO FAR SE MIAMI-DADE COUNTY AND THE ADJACENT WATERS
IF IT HOLDS. HOWEVER, AM EXPECTING A DISSIPATING TREND AS IT
ENCOUNTERS DRY LOW LEVEL AIR IN PLACE OVERHEAD. THE MIAMI SOUNDING
THIS MORNING SHOWED UNUSUALLY DRY AIR IN THE 1-10K FT LAYER. THIS
SHOULD ACT TO LIMIT AND DIMINISH ACTIVITY INCOMING FROM THE
SOUTHEAST. HAVE PLACED CHANCE POPS SE MIAMI-DADE COUNTY FOR THE
POSSIBILITY OF AT LEAST SOME RAIN MAKING IT IN THERE OVER THE NEXT
FEW HOURS. THE REST OF THE FORECAST LOOKS GOOD WITH TSTORMS
FOCUSING ACROSS THE LAKE REGION LATER THIS AFTERNOON. SEE
PREVIOUS DISCUSSION BELOW FOR FURTHER FORECAST DETAILS BEYOND
TODAY. /GREGORIA
PREV DISCUSSION... /ISSUED 644 AM EDT FRI AUG 30 2013/
AVIATION...
WITH A DRY, WEAK UPPER LEVEL LOW ALMOST DIRECTLY OVER SOUTH
FLORIDA, FAIRLY QUIET VFR CONDITIONS AREA EXPECTED THROUGH THE DAY
TODAY. THE EXCEPTION MAY BE A BRIEF PASSING SHOWER. HOWEVER,
CONFIDENCE IS LOW ON ANY TAF SITES BEING AFFECTED BY ANY SHOWERS,
AND WHAT SHOWERS DO DEVELOP WILL MOST LIKELY BE BRIEF. THE MOST
LIKELY AREA TO SEE ACTIVITY IS KPBI. THE MAIN AREA TO SEE ANY
CONVECTIVE ACTIVITY WILL BE IN THE INTERIOR AREA, CLOSER TO LAKE
OKEECHOBEE. THERE IS A CHANCE OF THUNDERSTORMS IN THAT AREA AS
WELL. THUS, HAVE LEFT ANY MENTION OF SHOWERS OR THUNDERSTORMS OUT
OF THE TAFS AT THIS TIME.
LIGHT AND VARIABLE WINDS WILL PERSIST INTO THE MID DAY. AROUND 18Z
THEY ARE EXPECTED TO PICK UP OUT OF THE SE BETWEEN 5 AND 10 KTS.
THEY WILL BECOME LIGHT AND VARIABLE ONCE AGAIN THIS EVENING.
PREV DISCUSSION... /ISSUED 308 AM EDT FRI AUG 30 2013/
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE FOR
THE HOLIDAY WEEKEND...
SHORT TERM...
AN UPPER LEVEL LOW WILL REMAIN OVER SOUTH FLORIDA TODAY INTO
SATURDAY...AS WEAK HIGH PRESSURE REMAINS OVER THE WESTERN
ATLANTIC WATERS. THIS WILL ALLOW FOR A STEERING FLOW OVER SOUTH
FLORIDA TO BE FROM THE SOUTHERLY DIRECTION WHICH WILL FOCUS THE
SHOWER AND THUNDERSTORM ACTIVITY OVER THE LAKE OKEECHOBEE REGION
TODAY AND AGAIN ON SATURDAY.
THERE IS ALSO SOME DRY AIR LOCATED BETWEEN 850 MB AND 700 MB IN
THE 00Z MIA SOUNDING. THIS DRY AIR WILL REMAIN IN PLACE TODAY INTO
SATURDAY HELPING TO REDUCE THE SHOWER AND THUNDERSTORM ACTIVITY
OVER SOUTH FLORIDA.
THEREFORE...THE POPS OVER SOUTH FLORIDA WILL RANGE FROM 20 PERCENT
OVER THE SOUTHERN AREAS TO 40 PERCENT OVER THE LAKE OKEECHOBEE
AREA FOR TODAY AND AGAIN ON SATURDAY. THE THUNDER THREAT WILL ALSO
BE LIMITED TO THE NORTHERN AREAS OF SOUTH FLORIDA FOR TODAY INTO
SATURDAY WHERE THE SEA BREEZES AND LAKE BREEZE COLLIDE.
THE UPPER LEVEL LOW SHOULD MOVE NORTHEAST LATE THIS LABOR DAY
WEEKEND INTO THE WESTERN ATLANTIC WATERS. THIS WILL ALLOW FOR THE
DRY AIR BETWEEN THE 700 MB AND 850 MB TO MOISTEN UP ALONG WITH
THE STEERING FLOW BECOMING MORE SOUTHEAST. THE SEA BREEZES WILL
ALSO DEVELOP EACH DAY AND PUSH INLAND. SO THE POPS WILL BE
INCREASED TO SCATTERED COVERAGE WITH THE HIGHEST POPS OVER THE
INTERIOR AREAS.
LONG TERM...
THE HIGH OVER THE WESTERN ATLANTIC WATERS SHOULD STRENGTHEN LATE
NEXT WEEK OVER THE WESTERN ATLANTIC WATERS AND EXTEND INTO THE
FLORIDA PENINSULA. THIS WILL ALLOW FOR THE EASTERLY WIND FLOW TO
REMAIN IN PLACE OVER SOUTH FLORIDA LATE NEXT WEEK ALONG WITH THE
DAILY SEA BREEZE DEVELOPMENT. SO WILL CONTINUE THE SCATTERED POPS
OVER SOUTH FLORIDA WITH THE BEST COVERAGE OVER THE INTERIOR AREA
FOR LATE NEXT WEEK.
THERE IS ALSO A TROPICAL WAVE OVER THE CENTRAL ATLANTIC WATERS
THAT IS FORECAST BY THE MODELS TO MOVE WEST-NORTHWEST NEXT WEEK
AND POSSIBILITY OVER SOUTH FLORIDA BY END OF NEXT WEEK. IF THIS
TREND CONDITIONS THEN THE POPS MAY HAVE TO BE RAISED UP FOR NEXT OF
NEXT WEEK.
MARINE...
THE WINDS OVER SOUTH FLORIDA WATERS THIS LABOR DAY WEEKEND WILL BE
FROM THE WEST TO SOUTHWEST DIRECTION AT 5 TO 10 KNOTS SWINGING TO
A EASTERLY DIRECTION BY LABOR DAY. THIS WILL KEEP THE SEAS IN BOTH
THE ATLANTIC AND GULF WATERS AT 2 FEET OR LESS. SO BOATING
CONDITIONS OVER SOUTH FLORIDA THIS LABOR DAY WEEKEND SHOULD BE
GOOD OUTSIDE OF ANY SHOWERS OR THUNDERSTORMS.
THE THREAT OF RIP CURRENTS THIS LABOR DAY WEEKEND AT BOTH THE
ATLANTIC AND GULF COAST BEACHES OF SOUTH FLORIDA LOOKS LOW AT
THIS TIME AS THE WINDS WILL BE 10 KNOTS OR LESS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 76 90 77 90 / 20 30 20 40
FORT LAUDERDALE 78 89 79 89 / 10 20 20 30
MIAMI 77 90 78 90 / 10 20 20 30
NAPLES 74 89 75 89 / 10 20 20 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...57/DG
AVIATION/RADAR...85/AG
AREA FORECAST DISCUSSION
NWS GRAY ME
1206 PM EDT FRI AUG 30 2013
.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA
TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE SATURDAY
BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH THROUGH NEW
ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON TUESDAY.
&&
.NEAR TERM /UNTIL 8 PM THIS EVENING/...
1202 PM...MINOR ESTF UPDATE TO 1ST PERIOD GRIDS TO REFLECT 16Z
MESONET AND CURRENT SATELLITE TRENDS.
PREV DISC...
930 AM...THE 12Z KGYX RAOB SHOWS THE MOISTURE TRAPPED BELOW THE
LOW LEVEL INVERSION. CONSEQUENTLY...I`VE INCREASED SKY GRIDS IN
THIS ESTF UPDATE AND LOWERED MAXIMUM TEMPERATURES A FEW DEGREES.
I ADJUSTED 1ST PERIOD GRIDS BASED ON SATELLITE TRENDS AND TO
REFLECT THE 13Z MESONET. NIL OTHER CHANGES. HAV A GUD DAY.
PREV DISC...
UPDATE...MINOR CHANGES TO REFLECT CURRENT OBSERVATIONAL TRENDS.
PREVIOUS DISCUSSION...STRATUS DECK FILLING BACK IN A LITTLE AS
NOCTURNAL COOLING AND WEAK LIFT CONTINUES N OF THE WARM FNT. THIS
SHOULD LIMIT MIN TEMPS THIS MORNING...AND IN FACT RAISE TEMPS A
FEW DEGREES ACROSS ERN AREAS THAT CLEARED OUT EARLIER.
LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE
AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY
AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR
AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH
PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE
NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING
THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND
TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST.
SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE
FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE
AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS.
HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT
MENTIONING IN THE GRIDS.
&&
.SHORT TERM /8 PM THIS EVENING THROUGH 6 PM SATURDAY/...
LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS
OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A
FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS
WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF
CLOUDS AND MILD MIN TEMPS.
ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE
AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE
BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER
INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL
SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE
FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY
MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER
VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND
CENTRAL MAINE AND NEW HAMPSHIRE.
THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY.
SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF
THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE
EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY
TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE
REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW
THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST
AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING.
THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR
INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK.
&&
.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR
DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR
CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR
CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND
SAT.
LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY.
THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN
CEILINGS AND VSBYS.
&&
.MARINE...
SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT.
LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5
FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
ES
AREA FORECAST DISCUSSION
NWS DULUTH MN
127 PM CDT FRI AUG 30 2013
.AVIATION.../18Z TAF ISSUANCE/
VFR CONDITIONS ARE EXPECTED ACROSS THE NORTHLAND TODAY INTO THIS
EVENING. AS THE NIGHT WEARS ON...AREAS OF FOG ARE EXPECTED TO
DEVELOP WITH LOCAL IFR/MVFR CONDITIONS.
&&
.PREV DISCUSSION... /ISSUED 1016 AM CDT FRI AUG 30 2013/
UPDATE...
REMOVED MENTION OF PRECIP OVER NRN WI THIS MORNING AND UPDATED
WORDING IN ZONE FORECAST. OTHERWISE...NO MAJOR CHANGES MADE TO THE
FORECAST.
PREV DISCUSSION... /ISSUED 643 AM CDT FRI AUG 30 2013/
AVIATION...12Z TAFS
A MVFR STRATUS DECK COVERED MUCH OF THE NORTHLAND THIS
MORNING. THE RAP 900/925MB PRES DEFICITS HAVE A DECENT HANDLE ON
THE CLOUDS...ALTHOUGH IT DOES SHOW THE CEILINGS A BIT TOO FAR TO
THE NORTH IN ONTARIO. WE SHOULD SEE CEILINGS SLOWLY RISE AND
BECOME SCATTERED EITHER LATER THIS MORNING OR THIS AFTERNOON. THEY
WILL HANG ON LONGEST OVER NORTHWEST WISCONSIN.
WE SHOULD ALSO SEE SOME CU DEVELOP TODAY WITH CONVECTIVE TEMPS
AROUND 70F. AFTER THIS STRATUS BREAKS UP...WE DID LEAVE CLOUDS
SCATTERED...BUT SOME BROKEN DECKS WILL BE POSSIBLE AS WELL.
TONIGHT...A WEDGE OF HIGH PRESSURE WILL CAUSE WINDS TO BE
LIGHT. SOME FOG WILL BE POSSIBLE...AND SOME MORE STRATUS MAY FORM
OVER OR AROUND LAKE SUPERIOR.
PREV DISCUSSION... /ISSUED 356 AM CDT FRI AUG 30 2013/
SHORT TERM...SFC LOW OVER CTRL LAKE SUPERIOR WITH TRAILING COLD
FRONT ACROSS NWRN WISC. POST FRONTAL CLOUDS ARE MOVING SOUTH UNDER
DEEPENING NRLY FLOW. AHEAD OF FRONT RESIDUAL STORMS DIMINISHING
OVER IRON COUNTY. MUCH OF CWA STILL UNDER MOIST ATMOSPHERE WITH
VERY SLOW REDUCTION IN SFC DEWPOINTS.
TODAY...WEDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION FROM
PARENT ANTICYCLONE NEAR HUDSON BAY. SFC DEWPOINTS WILL GRADUALLY
LOWER WITH SOME ASSISTANCE FROM BDRY LYR MIXING DURING THE DAY.
POST FRONTAL CLOUD COVER WILL TAKE A WHILE TO DIMINISH BASED ON
RAP13 925 CPD FCST. GENERAL CLOUD CANOPY SHOULD SLOWLY PUSH SOUTH
AND EAST INTO WISC ZONES DURING THE AFTN.
TONIGHT...SFC HIGH MOVES EAST OVERNIGHT AS SFC/MID LVL SYSTEM
MOVES INTO NRN PLAINS. WARM ADVECTION REGIME BEGINS BY 12Z SAT
OVER WRN CWA. MIN TEMPS LOWEST OVER INTERIOR WISC ZONES AND ERN
ARROWHEAD WHERE MAX RAD COOLING POTENTIAL EXISTS. TEMPS MAY NEED
ADJUSTMENT OVERNIGHT NEAR BORDERLAND AS INITIAL MID LVL WARM
ADVECTION CLOUDS MAY BE MORE EXTENSIVE THEN CURRENTLY FCST.
TOMORROW...A MID LVL TROF WITH AN ASSOCIATED SFC LOW WILL MOVE
INTO ONTARIO WITH A TRAILING COLD FRONT APPROACHING WRN EDGE OF CWA
BY LATE AFTN. INCREASING SRLY/SWRLY BDRY LYR FLOW WILL BECOME MORE
UNSTABLE IN THE AFTN. RW/TRW WILL DEVELOP OVER KOOCH COUNTY AROUND
MIDDAY AND GRADUALLY SPREAD EAST AND SOUTH TOWARDS TWIN PORTS BY
LATE AFTN. MAX TEMPS WILL PUSH ABOVE CLIMO ONCE AGAIN OVER MOST OF
THE CWA.
SATURDAY NIGHT THROUGH THURSDAY.
MAIN FOCUS IN THE EXTENDED PERIOD WILL BE A SHORTWAVE AND COLD FRONT
SATURDAY NIGHT.
THE MODELS ARE IN PRETTY DECENT AGREEMENT WITH A STRONG SHORTWAVE
AND COLD FRONT MOVING THROUGH THE REGION SATURDAY NIGHT. THE
STRONGEST PORTION OF THE WAVE WILL RIDE THE INTERNATIONAL BORDER.
PWAT VALUES AROUND 1.5 INCHES WILL BE OVER THE NORTHLAND AS THESE
FEATURES MOVE THROUGH. WE HAVE A GOOD CHANCE FOR SHOWERS AND STORMS
OVER MUCH OF THE NORTHLAND SATURDAY NIGHT. SOME OF THESE STORMS
COULD BE QUITE STRONG BUT WHETHER OR NOT THEY WILL BE SEVERE IS
STILL QUESTIONABLE. ADEQUATE SHEAR IS IN PLACE WHICH SUPPORTS
STRONGER STORMS.
THE CHANCE FOR SHOWERS AND A FEW THUNDERSTORMS WILL LINGER INTO
SUNDAY OVER PORTIONS OF THE NORTHLAND AS THE UPPER TROUGH SWINGS
THROUGH AND DUE TO COLDER AIR ALOFT. IT WILL BE MUCH COOLER...WITH
HIGHS FROM 65 TO 70 NORTH...AND THE MID SEVENTIES OVER OUR FAR
SOUTHEAST ZONES.
HIGH PRESSURE WILL TAKE HOLD MONDAY...AND PROVIDE DRY WEATHER INTO
THURSDAY. TEMPERATURES WILL SLOWLY INCREASE DURING THIS TIME...GOING
FORM THE MID SIXTIES TO LOWER SEVENTIES MONDAY...RISING THROUGH THE
SEVENTIES BY THURSDAY.
&&
.POINT TEMPS/POPS...
DLH 78 57 81 61 / 10 0 20 50
INL 79 60 83 57 / 10 20 50 50
BRD 81 60 87 60 / 10 10 30 50
HYR 79 56 85 63 / 20 0 10 60
ASX 74 57 80 63 / 20 0 10 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...TENTINGER
LONG TERM....DAP
AVIATION...DAP
AREA FORECAST DISCUSSION
NWS GLASGOW MT
218 PM MDT FRI AUG 30 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
NOT AS WARM THIS WEEKEND WITH WIND SATURDAY.
LOW PRESSURE OVER SASK THIS AFTERNOON WILL BEGIN TO SEND A COLD
FRONT OUR WAY TONIGHT WHEN AN UPPER LEVEL SYSTEM TO IT/S WEST
CATCHES UP. THIS FRONT IS EXPECTED TO PUSH SOUTHEAST THROUGH NE MT
SATURDAY MORNING. 850 MB TEMPS FALL A FEW DEGREES SATURDAY AND
ATMOSPHERE MIXES TO ABOUT 750 MB. WINDS AT THAT LEVEL LOOK TO BE
ABOUT 25-30 KTS SO 20 TO 30 MPH SURFACE WINDS CAN BE EXPECTED.
THESE WINDS ARE LOOKING TO OCCUR FROM ABOUT NOON TO 8 PM OVER FORT
PECK LAKE...SO WILL GO AHEAD AND ISSUE A LAKE WIND ADVISORY FOR
THIS PERIOD.
OTHERWISE...SOME MID-LEVEL INSTABILITY MAY BUBBLE UP A SHOWER/STORM
LATE THIS AFTERNOON. THE HRRR AS USUAL IS EXCITED ABOUT IT WHILE THE
OTHER MODELS (INCLUDING THE RUC) ARE MUCH DRIER. THE NAM IS SHOWING
THIS TO OCCUR LATER TONIGHT IN THE SOUTHERN ZONES...FINALLY EXITING
INTO THE DAKOTAS SATURDAY AFTERNOON.
SURFACE HIGH PRESSURE THEN BUILDS INTO THE AREA SATURDAY NIGHT
PROVIDING LIGHT WINDS...NEAR NORMAL TEMPS AND CLEAR SKIES THROUGH
SUNDAY. ENJOY! TFJ
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
THE LONG TERM FORECAST PERIOD IS CHARACTERIZED BY A SIGNIFICANT
AND AMPLIFIED WEATHER PATTERN...BASICALLY SPLIT BETWEEN TWO
DIFFERENT WEATHER REGIMES.
SUNDAY NIGHT THROUGH WEDNESDAY AFTERNOON...THE CENTRAL CONUS RIDGE
AND THE PACIFIC NORTHWEST LOW BUTT UP AGAINST EACH OTHER IN A
STRUGGLE FOR DOMINANCE THAT DOES NOT COME TO A RESOLUTION UNTIL
LATE WEDNESDAY NIGHT.
IT SHOULD BE NOTED THAT THE LARGE SCALE MODELS HINT AT A SHORT
WAVE DISTURBANCE RIDING UP AND AROUND THE RIDGE OF HIGH PRESSURE
MAKING ITS WAY THROUGH EASTERN MONTANA TUESDAY MORNING THROUGH
TUESDAY AFTERNOON...LIKELY BRINGING ONLY ISOLATED PRECIPITATION TO
THE AREA.
THE BIGGER STORY BEGINS OVERNIGHT WEDNESDAY NIGHT AS THE LARGE
UPPER LEVEL LOW PRESSURE SYSTEM FINALLY MOVES INLAND OVER THE
PACIFIC NORTHWEST...TURNING OUR FLOW ALOFT FROM THE SOUTHWEST AND
SOUTH. THIS WILL LIKELY PUMP SIGNIFICANT AMOUNTS OF PACIFIC
MOISTURE OVER THE NORTHERN ROCKIES AND NORTHERN HIGH PLAINS. WITH
EACH MODEL RUN...THE CONSENSUS IMPROVES REGARDING THE TIMING AND
PLACEMENT OF THIS UPPER LOW INTO THE INTER-MOUNTAIN NORTHWEST.
AT THIS TIME...SIGNIFICANT DIFFERENCES WITH THIS WEATHER REGIME
CHANGE BEGIN TO EMERGE EARLY THURSDAY MORNING AS THE AGGRESSIVE GEM
PUSHES FASTER AHEAD...FOLLOWED BY THE SLOWER GFS AND THEN THE
SLOWEST EC. FOR NOW...CAN ONLY BROAD-BRUSH THE END OF THE EXTENDED
FORECAST PERIOD WITH A WETTER WEATHER PATTERN. WOULD EXPECT THINGS
TO COME MORE INTO FOCUS OVER THE NEXT FEW DAYS. BMICKELSON
PREVIOUS LONG TERM DISCUSSION...
UPPER RIDGE WILL BE OVER THE AREA MOST OF THE WEEK WITH WARM AND
MAINLY DRY WEATHER. THERE WILL BE SUMMER LIKE TEMPERATURES NEAR 90
MONDAY AND TUESDAY.
ECMWF STILL WANTS TO BRING A BACK DOOR COLD FRONT THROUGH THE AREA
TUESDAY NIGHT WHILE THE GFS KEEP THE FRONT TO THE EAST. THIS HAS
THE ECMWF FORECASTING COOLER TEMPERATURES ON WEDNESDAY. WILL GO
SOMEWHAT COOLER ON WEDNESDAY FOR NOW.
MODELS EVENTUALLY WANT TO BRING AN UPPER LOW/TROUGH INLAND TOWARDS
THE END OF NEXT WEEK. THE FLOW ALOFT IS EXPECTED TO TURN TO THE
SOUTHWEST AROUND THURSDAY ALLOWING FOR SOME INCREASE IN MOISTURE.
WILL MENTION A SLIGHT CHANCE OF THUNDERSTORMS STARTING THURSDAY
AFTERNOON IN THE WEST AND SPREADING TO THE ENTIRE AREA BY FRIDAY.
FORRESTER
&&
.AVIATION...
MAINLY VFR CONDITIONS WILL PREVAIL FOR ALL TAF SITES.
LATELY RIVER VALLEY FOG HAS BEEN ABLE TO MAKE ITS WAY INTO KOLF
BUT SEEMS LESS LIKELY NOW OVER THE NEXT FEW DAYS AS NORTHWESTERLY
SURFACE WINDS AND DRIER ARE ARE EXPECTED TO MOVE THROUGH THE AREA
WITH A COLD FRONT. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE
TODAY AND TONIGHT. WIND SPEEDS WILL BE 10 KNOTS OR LESS TODAY AND
TONIGHT. EXPECT WINDY NORTHWEST WINDS LATER ON SATURDAY...AROUND
20G30KT. BMICKELSON
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM NOON TO 8 PM MDT SATURDAY FOR FORT PECK
LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS HASTINGS NE
430 PM CDT FRI AUG 30 2013
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 430 PM CDT FRI AUG 30 2013
THE MAIN HIGHLIGHTS OF THE NEXT 36 HOURS INCLUDE ONE MORE DAY OF
NOTABLE LATE SUMMER HEAT ON SATURDAY BEFORE READINGS RETURN TO
MORE SEASONAL LEVELS FOR SUNDAY...ALONG WITH STILL HIGHLY-
UNCERTAIN THUNDERSTORM CHANCES BOTH TONIGHT AND ESPECIALLY FOR
SATURDAY NIGHT. WANT TO STATE OFF THE TOP THAT MODELS VARY
CONSIDERABLY ON THE PROBABILITY/COVERAGE OF CONVECTION SATURDAY
NIGHT...AND THUS POPS CONTINUE TO BE CAPPED AT NO MORE THAN 30-40
PERCENT ACROSS THE CWA.
STARTING OFF LATE THIS AFTERNOON...20Z OBJECTIVE SURFACE ANALYSIS
DEPICTS A SURFACE TROUGH/VERY WEAK COLD FRONT STRETCHED FROM
NORTHWEST KS INTO CENTRAL IA...WITH THE VAST MAJORITY OF THE CWA
POSITIONED JUST NORTH OF THIS BOUNDARY. AS A RESULT...BREEZES THIS
AFTERNOON HAVE PREVAILED FROM THE EAST-NORTHEAST AT SPEEDS
GENERALLY AROUND 10 MPH WITH OCCASIONAL HIGHER GUSTS.
HOWEVER...THIS HAS BY NO MEANS BEEN A COOLING NORTHERLY WIND
COMPONENT...AS HIGH TEMPS ARE ON TARGET TO RANGE FROM THE LOW-MID
90S CENTRAL/NORTHEAST...TO THE UPPER 90S TO AROUND 104 IN
SOUTHERN ZONES. FURTHERMORE...THE FAIRLY LIGHT EAST-NORTHEAST
BREEZE HAS ALLOWED DEWPOINTS ACROSS MAINLY THE NORTHEAST 2/3 OF
THE CWA TO REMAIN WELL UP AROUND 70...RESULTING IN POSSIBLY THE
MOST WIDESPREAD COVERAGE OF 100-105 HEAT INDEX VALUES WE HAVE SEEN
ALL WEEK...WITH VALUES IN ALL AREAS LIKELY SAFELY UNDER 100 BY
01Z/8PM. ALOFT...WATER VAPOR IMAGERY SHOWS THE CWA LOCATED
NORTHEAST OF THE CENTER OF THE EXPANSIVE MID/UPPER RIDGE AXIS
CENTERED OVER CO...RESULTING IN NORTH/NORTHWEST FLOW OVERHEAD.
WHILE WATER VAPOR AND MODELED VORTICITY FIELDS HINT AT SOME SUBTLE
PERTURBATIONS HELPING KICK OFF HIGH PLAINS CONVECTION OFF TO OUR
WEST AT THIS HOUR...BY FAR THE MOST NOTABLE SHORTWAVE OF INTEREST
FOR THE NEXT FEW DAYS WEATHER IS SHIFTING EAST INTO SOUTHERN
ALBERTA AT THIS TIME. VISIBLE SATELLITE LATE THIS AFTERNOON SHOWS
ESSENTIALLY CLOUD-FREE SKIES OVER THE VAST MAJORITY OF THE
CWA...WITH ONLY SOME VERY HIGH BASED CUMULUS DEVELOPING FROM
INTENSE HEATING IN OUR FAR SOUTHERN KS ZONES.
TURNING TO THE EVENING/OVERNIGHT HOURS...FROM A BASIC SENSE HAVE
MADE VERY LITTLE CHANGE TO THE PREVIOUS FORECAST. HAVE KEPT LOW
END 20-30 PERCENT STORM CHANCES CONFINED TO ROUGHLY THE NORTHWEST
1/3 OF THE CWA...WITH TWO POSSIBLE SCENARIOS ENVISIONED AND
PORTRAYED BY VARIOUS MODELS. STARTING WITH THE BIG PICTURE
ALOFT...VERY SUBTLE HEIGHT FALLS WILL OCCUR AS THE LARGE RIDGE
AXIS FLATTENS JUST A BIT IN RESPONSE TO THE AFOREMENTIONED CANADIAN
SHORTWAVE TROUGH SHIFTING EAST TO JUST NORTH OF THE MT/ND BORDER
BY SUNRISE. CLOSER TO HOME...VERY SUBTLE MID LEVEL
PERTURBATIONS...POSSIBLY CONVECTIVELY DRIVEN...WILL CONTINUE
SHIFTING EAST TOWARD/INTO THE CWA FROM THE CENTRAL HIGH PLAINS.
SOME MODELS...NAMELY THE HRRR AND 12Z 4KM WRF-NMM...ARE
SURPRISINGLY AGGRESSIVE IN DRIVING HIGH PLAINS CONVECTION EASTWARD
INTO AT LEAST WESTERN PORTIONS OF THE CWA THIS EVENING...BUT WITH
A GENERAL TREND OF KILLING OFF CONVECTION AS IT GETS TOWARD
CENTRAL PORTIONS OF THE CWA LIKELY IN RESPONSE TO INCREASING CINH.
ALTHOUGH A FEW STORMS ARE ALREADY EVIDENT 100+ MILES WEST OF THE
CWA...UNCERTAINTY IS QUITE HIGH WHETHER OR NOT ANY OF THIS WILL
ACTUALLY SLIP INTO OUR AREA...AND THUS OPTED TO KEEP LOW POPS
CONFINED TO WESTERN COUNTIES AND NOT ADVERTISE ANYTHING ACROSS THE
MAJORITY OF THE AREA...BUT THIS WILL NEED WATCHED. LATER IN THE
NIGHT...MODELS SUCH AS THE RAP KICK OFF A POTENTIALLY SEPARATE
AREA OF HIGH-BASED CONVECTION IN OUR NORTHWEST COUNTIES POSSIBLY
IN RESPONSE TO MID-LEVEL THETA-E ADVECTION...BUT AGAIN THIS IS
MAINLY IN THE AREA ALREADY COVERED WITH LOW POPS. IF STORMS
DEVELOP/MOVE IN THIS EVENING/OVERNIGHT...WOULD BE SURPRISED TO SEE
MORE THAN SMALL SUB-SEVERE HAIL. OTHERWISE...BREEZES TONIGHT WILL
AVERAGE VERY LIGHT/EASTERLY...AND MADE LITTLE IF ANY CHANGE TO
OVERNIGHT LOWS WITH MAINLY 66-71.
TURNING TO THE SATURDAY DAYTIME/SATURDAY NIGHT HOURS...AGAIN ON
THE SURFACE THERE HAS BEEN LITTLE NOTICEABLE CHANGE FROM THE
PREVIOUS FORECAST...WITH THE OVERALL BEST CHANCES FOR RAIN/STORMS
DURING THE CURRENT VALID 7-DAY FORECAST ARRIVING SATURDAY
NIGHT...ALTHOUGH BY FAR FROM A SURE THING. ON THE LARGE
SCALE...THE FAIRLY VIGOROUS SHORTWAVE TROUGH ALONG CENTRAL
PORTIONS OF THE U.S./CANADIAN BORDER ON SATURDAY MORNING WILL
SLIDE EAST-SOUTHEAST TO OVER/NEAR LAKE SUPERIOR BY SUNRISE SUNDAY
MORNING...WITH THIS WAVE LOWERING HEIGHTS FURTHER OVER THE LOCAL
AREA AND SHUNTING THE RIDGE SLIGHTLY OFF TO THE SOUTHWEST A BIT.
AT THE SURFACE...BY FAR THE BIG STORY IS A LEGITIMATE COLD FRONT
THAT WILL BE FORCED SOUTHWARD INTO THE CENTRAL PLAINS FROM THIS
WAVE. DURING THE DAYTIME HOURS...THERE IS GOOD AGREEMENT THIS
FRONT WILL BE POSITIONED AT LEAST SLIGHTLY NORTHWEST OF THE CWA
THROUGH LATE AFTERNOON...BEFORE PASSING THROUGH SOMEWHAT
AGGRESSIVELY DURING THE NIGHT AS FAR AS SUMMER COLD FRONTS
GO...WITH ALL AREAS EXPECTED TO HAVE A STEADY 10+ MPH NORTH BREEZE
AND INCREASINGLY COOLER/DRIER AIR BY SUNRISE SUNDAY MORNING. DUE
TO THE CWA REMAINING AHEAD OF THE FRONT DURING THE DAY...ONE MORE
HOT/STEAMY AFTERNOON IS IN STORE...WITH MAYBE ONLY A BIT MORE IN
THE WAY OF MID/HIGH CLOUDS POSSIBLE HOLDING SOME AREAS A TAD
COOLER THAN TODAY...BUT STILL AIMING FOR LOW-MID 90S
CENTRAL/NORTHEAST TO NEAR 100 SOUTH/SOUTHWEST...WITH HEAT INDEX
VALUES AGAIN AROUND 100 OR SLIGHTLY HIGHER. AS FOR DAYTIME
CONVECTIVE CHANCES...THERE IS ADMITTEDLY SOME UNCERTAINTY
HERE...AS SOME MODELS SUCH AS THE NAM SUGGEST THAT ESPECIALLY THE
WESTERN 1/2 OF THE CWA COULD SEE SOME LIKELY HIGH-BASED DAYTIME
CONVECTION...EVEN IN THE MORNING...POSSIBLY A CONTINUATION OF SOME
ACTIVITY THAT MIGHT DEVELOP LATE TONIGHT. HOWEVER...FORECAST
SOUNDINGS AND A CONCEPTUAL MODEL OF THIS PATTERN SUGGEST THAT VERY
WARM MID LEVEL TEMPERATURES ARE MORE LIKELY TO INHIBIT DAYTIME
CONVECTION THAN SUPPORT IT. SO ALTHOUGH ITS NO GUARANTEE...LEFT
POPS BELOW THE MENTIONABLE 15+ PERCENT THRESHOLD IN THE MORNING AND
THROUGH MID-AFTERNOON...BUT LEFT SLIGHT CHANCES MAINLY IN THE
WESTERN 1/2 DURING THE LATE AFTERNOON JUST IN CASE SOMETHING CAN
GET GOING IN THE HOT/DEEPLY MIXED AIRMASS AHEAD OF THE FRONT.
CERTAINLY THE BETTER LARGE-SCALE SUPPORT TO BREAK THROUGH THE CAP
AND SUPPORT CONVECTION COMES SATURDAY NIGHT...AS THE SURFACE COLD
FRONT PASSES THROUGH AND IS ACCOMPANIED/FOLLOWED BY A DECENT AXIS
OF MID LEVEL FRONTOGENESIS. EVEN SO...WITH THE MAIN TRACK OF THE
PARENT SHORTWAVE TROUGH TRACKING HUNDREDS OF MILES NORTHEAST OF
THE CWA...THERE ARE PLENTY OF QUESTIONS ABOUT HOW WIDESPREAD THIS
CONVECTION WILL BE. FOR EXAMPLE...WILL IT SWEEP THROUGH FROM
NORTHWEST-SOUTHEAST IN A FAIRLY SOLID LINE AS THE 12Z NAM WOULD
SUGGEST...OR WILL IT BE VERY HIT-AND-MISS AND IN FACT MISS THE
MAJORITY OF THE AREA ALTOGETHER AS THE 12Z 4KM-WRF NMM
REFLECTIVITY PROG WOULD SUGGEST. WITH THIS STILL BEING 24+ HOURS
OUT...OPTED TO PLAY POPS FAIRLY STATUS QUO FOR NOW...CAPPING THEM
IN THE 30-40 PERCENT RANGE GIVEN THIS DEGREE OF UNCERTAINTY.
IF/WHEN STORM FORM...CERTAINLY CANNOT RULE OUT AT LEAST A MARGINAL
SEVERE THREAT...WITH THE NAM ADVERTISING 2000+ J/KG OF CAPE IN THE
850-700MB LAYER IN THE EVENING...BUT IN THE PRESENCE OF ONLY
25-30KT OF DEEP LAYER SHEAR. ITS CERTAINLY POSSIBLE THAT IF ENOUGH
STORMS FORM AND DEVELOP INTO A FORWARD-PROPAGATING LINE THAT AN
ENHANCED WIND THREAT COULD MATERIALIZE...BUT THIS IS ALL
PREDICATED ON HOW WIDESPREAD DEVELOPMENT ULTIMATELY IS. NO MATTER
WHAT...ROUGHLY THE NORTHWEST 1/3 TO 1/2 OF THE CWA SHOULD BE CLEAR
OF STORM CHANCES BY AROUND MIDNIGHT OR SHORTLY THEREAFTER...WITH
THE LATE NIGHT FOCUS IN THE SOUTHEASTERN 1/2. LOW TEMPS BY SUNRISE
SUNDAY ARE FORECAST TO RANGE LOW 60S NORTH TO NEAR 70 FAR
SOUTHEAST.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 430 PM CDT FRI AUG 30 2013
MAIN CONCERNS ARE CHANCES FOR THUNDERSTORMS SUNDAY MORNING AND
WEDNESDAY EVENING.
ON THE LARGE SCALE...THE WEATHER PATTERN WILL BE SWINGING TO A
NORTHWEST FLOW REGIME AS THE UPPER LEVEL RIDGE THAT HAS BEEN
PERSISTENT OVER THE AREA THE LAST WEEK OR SO RETROGRADES WEST. THIS
CHANGE IN FLOW WILL RESULT IN TEMPERATURES ABOUT 10 DEGREES COOLER
THAN THIS WEEK AND SOME LOW CHANCES FOR RAIN AS FRONTAL BOUNDARIES
INTERMITTENTLY MOVE THROUGH THE AREA.
MODELS SUGGESTING LINGERING STORMS POSSIBLE EARLY SUNDAY MORNING
BEFORE CONVECTION EXITS SOUTHEAST OF THE AREA. WE LEFT SMALL CHANCES
OF RAIN IN OVER THE EXTREME SOUTHEAST CORNER OF THE CWA SUNDAY
MORNING AS THE FRONT SAGS OUT OF THE AREA. ALL MODELS SUGGEST A
CHANCE FOR STORMS WEDNESDAY EVENING AS ANOTHER COOL FRONT MOVES
THROUGH THE AREA. THERE IS A MARGINAL THREAT THAT A FEW OF THE
STORMS MAY PRODUCE SMALL HAIL AND GUSTY WINDS WEDNESDAY NIGHT
DUE TO LOW TO MARGINAL INSTABILITY AND WEAK SHEAR.
OTHER THAN THOSE TWO PERIODS...HIGH PRESSURE SHOULD BE THE DOMINANT
WEATHER FEATURE. SO DRY AND NEAR TO SLIGHTLY ABOVE NORMAL TEMPS WILL
BE THE RULE MOST DAYS.
&&
.AVIATION...(FOR THE 18Z KGRI TAF THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1218 PM CDT FRI AUG 30 2013
EXPECT NORTHEASTERLY FLOW TODAY AS A WEAK SURFACE TROUGH HAS
TRANSITED THE AREA. BOTH CEILINGS AND VISIBILITIES ARE EXPECTED TO
REMAIN VFR THROUGH THE PERIOD. A FEW MODELS ARE HINTING AT A
CHANCE FOR PRECIPITATION OVERNIGHT. CONFIDENCE IS CURRENTLY LOW AS
TO WHETHER IT WILL REACH THE GRI AIRPORT.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
LONG TERM...EDDY
AVIATION...BEDA
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
308 PM CDT FRI AUG 30 2013
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 307 PM CDT FRI AUG 30 2013
TONIGHT THROUGH SATURDAY...A WEAK UPPER LEVEL DISTURBANCE...
CURRENTLY ACROSS THE WYOMING...WILL MOVE ACROSS THE FCST AREA
TONIGHT SPAWNING A FAIRLY ORGANIZED AREA OF TSTMS. ALL MODELS SHOW
K INDICES INCREASING TO AROUND 40C OR GREATER. THE RAP AND OTHER
MODELS SHOW PRECIPITABLE WATER INCREASING TO 1.50 INCHES OR
GREATER. FCST STORM MOTION OF 10KT OR LESS WOULD SUPPORT LOCALLY
HEAVY RAINFALL AND WEAK WINDS ALOFT 30KT OR LESS AT AND BELOW
300MB SUGGEST OUTFLOW DOMINANT COLD POOL DRIVEN BOW SEGMENTS
CAPABLE OF GUSTY WINDS.
LOW LEVEL EASTERLIES AND WEAK WESTERLIES ALOFT PRODUCE BULK SHEAR OF
35 TO 40 KT SO SOME STORMS THIS EVENING COULD BECOME SEVERE WITH
WIND DAMAGE AND LARGE HAIL. SPC PROVIDED THIS DISCUSSION AT 227 PM
CDT...RECENT LIGHTNING WITHIN THE CONVECTION ALONG THE BLACK
HILLS AND LARAMIE MOUNTAINS HAS INCREASED CONFIDENCE THAT THE
ENVIRONMENT ACROSS THE CNTRL PLAINS IS GRADUALLY BECOMING MORE
SUPPORTIVE OF SURFACE-BASED CONVECTIVE INITIATION. 12Z RAP SOUNDING
MODIFIED FOR 19Z SURFACE OBSERVATION -- 93/62 -- YIELDS STRONG
SURFACE-BASED INSTABILITY /SBCAPE OVER 3000 J PER KG/ AND LITTLE
REMAINING CINH. INCREASED CONVERGENCE ALONG A WEAK SURFACE TROUGH
AND CONTINUED DESTABILIZATION FOSTERED BY ISOLATION IS EXPECTED TO
RESULT IN ADDITIONAL SURFACE-BASED CONVECTIVE DEVELOPMENT DURING THE
NEXT HOUR OR TWO.
THE STORM COMPLEX COULD MOVE MOSTLY EAST ACCORDING TO THE RAP MODEL
OR TAKE A SOUTHEAST TURN AS INDICATED BY THE HRRR. EITHER WAY THE
CONVECTION WILL AFFECT MOST OF THE FCST AREA AND EXIT SOUTH OR EAST
BY AROUND 12Z.
THIS TSTM COMPLEX SHOULD SET UP A FRONTAL BOUNDARY FOR ADDITIONAL
STORM DEVELOPMENT SATURDAY AFTN AND BEYOND WITH THE BEST SHEAR AND
INSTABILITY ACROSS NCNTL NEB NEAR KANW AND KONL. THE MODELS HAVE A
TOTALLY DIFFERENT IDEA IN MIND WITH THE FRONT AND LIFT IT RAPIDLY
NORTH BY 15Z SATURDAY MORNING AND THEN DROP ANOTHER COLD FRONT
THROUGH DURING THE AFTN. SO THERE IS A DISCONNECT IN CONVENTIONAL
STORM THEORY VS THE MODELS. IF THE FRONT IS DOES NOT RETREAT NORTH
AS QUICKLY THAN STORM DEVELOPMENT COULD BE MUCH FARTHER
SOUTH...PERHAPS OVER KS. THE FCST USES A BLEND OF NAM...GEMREG...GFS
AND ECM FOR A 30 POP FROM 20Z ONWARD...MAINLY SOUTH AND EAST OF
KVTN/KIML.
TEMPERATURES ARE A BLEND OF TRIED AND TRUE MODEL DATA PLUS BIAS
CORRECTION FOR HIGHS IN THE LOWER 90S NORTH TO UPPER 90S SOUTH.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 307 PM CDT FRI AUG 30 2013
SATURDAY NIGHT THROUGH LABOR DAY...
COLD FRONT SHOULD STRETCH FROM NEAR ANW THROUGH LBF AND IML EARLY
SATURDAY EVENING. DO EXPECT SCATTERED SHOWERS AND THUNDERSTORMS
ALONG AND AHEAD OF THE FRONT. COVERAGE MAY END UP LESS ACROSS SWRN
NEBR WHICH WILL BE FURTHER REMOVED FROM COOLER TEMPERATURES ALOFT
ASSOCIATED WITH MAIN UPPER TROUGH ACROSS MINNESOTA. ONLY A SLIGHT
CHANCE FOR THUNDERSTORMS FAR SOUTHEAST AFTER MIDNIGHT. DRY AND
LESS HOT SUNDAY AND LABOR DAY. HIGHS SUNDAY FORECAST VERY NEAR
PREVIOUS FROM NEAR 83 NCTRL AND 85 TO 88 SOUTHWEST. NORTHERLY WINDS
SUNDAY LOOK FAIRLY LIGHT FROM 5 TO 15 MPH WEST AND 10 TO 20 MPH
EAST. ON LABOR DAY...NORTHWEST FLOW ALOFT WILL CONTINUE WITH A
RETURN SOUTHEAST FLOW AT THE SURFACE AND HIGHS FROM NEAR 83
NORTHEAST TO NEAR 90 WEST TIER. SOUTHERLY WINDS MONDAY FROM 10 TO
20 MPH WEST TO 5 TO 15 MPH EAST.
ON TUESDAY THROUGH FRIDAY...
A HEAT UP AGAIN LIKELY AS UPPER RIDGE PERSISTS OVER COLORADO AND
TROUGHING INCREASES ACROSS THE PAC NW AND NORTHEASTERN U.S. A WEAK
COLD FRONT AND DISTURBANCE IN NORTHWEST FLOW ALOFT INDICATED BY
THE GFS AND ECMWF. THIS FRONT ASSOCIATED WITH A DEEP UPPER LOW
MOVING ACROSS HUDSON BAY. AS A RESULT OF ECMWF CONSISTENCY AND
FAIR AGREEMENT BY THE GFS...WILL INTRODUCE A SLIGHT CHANCE FOR
THUNDERSTORMS WEDNESDAY NIGHT. AN OTHERWISE DRY EXTENDED. HIGHS
FORECAST IN THE UPPER 80S TO LOW 90S MOST AREAS WITH MID 90S PARTS
OF SWRN NEBR.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1221 PM CDT FRI AUG 30 2013
ALL MODELS ARE DEVELOPING SCATTERED DEEP CONVECTION ACROSS WRN NEB
THIS AFTN AROUND 21Z-22Z. STORM ACTIVITY SHOULD MOVE EAST INTO NCNTL NEB
BY OR DURING THE EVENING. THE HRRR SUGGESTS STORMS COULD HIT KVTN
AND KLBF BETWEEN 01Z AND 04Z. THE HRRR AND RAP INDICATE BOWING
TSTM SEGMENTS DEVELOPING IN THE WEST WHICH COULD COALESCE NORTH
AND SOUTH ACROSS THE FCST AREA THIS EVENING. THE STORM ACTIVITY
SHOULD BE MOSTLY EAST OF THE FCST AREA BY 09Z WITH VFR THEREAFTER.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1222 PM CDT FRI AUG 30 2013
.SYNOPSIS...
ISSUED AT 345 AM CDT FRI AUG 30 2013
A STAGNANT H5 PATTERN REMAINS IN PLACE ACROSS THE CENTRAL CONUS
TONIGHT WITH A BROAD RIDGE OF HIGH PRESSURE EXTENDING FROM THE
SRN ROCKIES WELL INTO CENTRAL CANADA. WV IMAGERY ATTM IS
INDICATING A COUPLE OF SHORTWAVES...THE FIRST OVER EASTERN
KANSAS...AND A SECOND OVER UTAH AND SWRN WYOMING. AT THE
SURFACE...A WEAK FRONTAL BOUNDARY HAS PUSHED INTO NORTH CENTRAL
AND WESTERN NEBRASKA THIS EVENING...WHICH HAS INCREASED DEW
POINTS INTO THE MID AND UPPER 60S...AND RESULTED IN LIGHT
NORTHERLY WINDS. TEMPERATURES AS OF 3 AM CDT...RANGED FROM 65 AT
NORTH PLATTE...TO 74 AT ONEILL AND AINSWORTH.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 345 AM CDT FRI AUG 30 2013
TODAY AND TONIGHT...FORECAST CHALLENGES OVER THE NEXT 24 HOURS
ARE TEMPERATURES TODAY...AND PRECIPITATION CHANCES TONIGHT. FOR
TODAY...SOME LIMITED RELIEF FROM THE TRIPLE DIGIT HEAT WILL BE
SEEN NORTH OF THE FRONTAL BOUNDARY ACROSS NORTHERN NEBRASKA THIS
AFTERNOON...AS HIGHS TOP OUT IN THE MIDDLE 90S. SOUTH OF THE
FRONT...TEMPS WILL SURGE TOWARD THE CENTURY MARK...TOPPING OUT AT
99 FOR NORTH PLATTE AND OGALLALA AND 102 FOR IMPERIAL. LATER THIS
AFTERNOON...THE BEFORE MENTIONED FRONTAL BOUNDARY...WILL LIFT TO
THE EAST AS A WEAK WARM FRONT. MID LEVEL LIFT WILL BEGIN TO
INCREASE LATE THIS AFTERNOON AND THIS EVENING AS MID LEVEL WARM
AIR ADVECTION INCREASES IN ADVANCE OF AN APPROACHING SHORT WAVE
TROUGH. MID LEVEL LIFT...COMBINED WITH LOW LEVEL CONVERGENCE
INVOF OF THE FRONT...WILL INCREASE THE THREAT FOR THUNDERSTORMS
LATER THIS AFTERNOON IN THE NORTHWEST...TRANSITIONING EAST TO THE
REMAINDER OF THE FORECAST AREA THIS EVENING. THE ONE LIMITING
FACTOR...MAY BE CAP STRENGTH...ESPECIALLY IN THE SRN CWA...AND
FOR THAT REASON...WILL LIMIT POPS TO SLIGHT CHANCE ATTM...AS
THUNDERSTORM INITIATION IS CONDITIONAL ATTM. ONE DISCLAIMER
THOUGH...IF STORMS CAN FIRE...SURFACE TO H400 SHEAR TOPS OUT AT
40 KTS THIS EVENING...SO SOME STRONG TO LOW END SEVERE STORMS MAY
BE POSSIBLE...ESPECIALLY OVER NORTHERN NEBRASKA.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 345 AM CDT FRI AUG 30 2013
SATURDAY IS EXPECTED TO BEGIN WITH PARTLY TO MOSTLY SUNNY SKIES.
COLD FRONT WILL BE PUSHING INTO FAR NW NEB. BY AFTERNOON HEATING
ALONG AND AHEAD OF THE FRONT SHOULD BE ENOUGH TO BREAK THROUGH
THE CAP. WITH THE INCREASING OF CLOUDS BY MID TO LATER
AFTERNOON...HAVE TEMPS ONLY GOING INTO THE LOWER TO MID 90S
NORTHERN AND UPPER 90S SOUTH. FRONT IS SLOWER WITH THE 00Z RUN SO
HAVE DELAYED ONSET OF POPS UNTIL THE AFTERNOON. SATURDAY NIGHT
THE FRONT WILL BE CROSSING THE REST OF THE CWA...WITH DECREASING
CLOUDS AND AN END TO POPS BEHIND THE FRONT.
SUNDAY AND LABOR DAY WILL BE PLEASANT DAYS AS COOLER HIGH
PRESSURE SETTLES IN BEHIND THE FRONT. 850 MB TEMPS DROP TO AROUND
20 DEGREES WITH GUIDANCE SHOWING HIGHS IN THE 80S...WHICH IS
SEASONAL. SUBSIDENCE BEHIND THE FRONT WILL LIMIT CLOUDS AND HIGH
PRESSURE WILL KEEP AFTERNOON WINDS AROUND 15 MPH OR LESS.
BY TUESDAY THE MODELS ARE IN GOOD AGREEMENT BRINGING AN UPPER
LEVEL CLOSED LOW TOWARDS THE PAC NW WEST...WHICH STALLS THROUGH
MID WEEK...DUE TO THE BLOCKING RIDGE. SOME DIVERGENCE OF THE
MODELS THEN AS THE GFS BRINGS IT ONSHORE INTO WA/OR...WHILE THE
EC LIFTS THE LOW INTO SW CANADA. DOWN STREAM IS A
PERSISTENT/BLOCKING RIDGE WHICH REPOSITIONS ITSELF OVER THE
CENTRAL ROCKIES INTO THE HIGH PLAINS. HEIGHTS INCREASE QUICKLY
FOR TUESDAY AND TEMPS SHOULD WARM BACK INTO THE 90S FOR MOST
AREAS. RIDGE THAT REDEVELOPS IS NOT QUITE AS STRONG AS CURRENT
AND THINK HIGHS WILL GENERALLY REMAIN BELOW 100. ALSO WE ARE
GETTING INTO THE FIRST WEEK OF SEPTEMBER WITH SHORTER DAYLIGHT
HOURS AND LESS OCCURRENCES OF TRIPLE DIGITS. STILL HAVE A FEW
RECORDS AT 100 OR ABOVE SO IT WILL BE POSSIBLE AND NEED TO BE
WATCHED. CURRENT FORECAST IS CLOSE TO GUIDANCE WHICH IS HIGHEST
IN THE SW NEB...WITH MID 90S. THE STORM TRACK LOOKS TO RIDE THE
RIDGE AND CROSS THE DAKOTAS SO A DRY FORECAST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1221 PM CDT FRI AUG 30 2013
ALL MODELS ARE DEVELOPING SCATTERED DEEP CONVECTION ACROSS WRN NEB
THIS AFTN AROUND 21Z-22Z. STORM ACTIVITY SHOULD MOVE EAST INTO NCNTL NEB
BY OR DURING THE EVENING. THE HRRR SUGGESTS STORMS COULD HIT KVTN
AND KLBF BETWEEN 01Z AND 04Z. THE HRRR AND RAP INDICATE BOWING
TSTM SEGMENTS DEVELOPING IN THE WEST WHICH COULD COALECSE NORTH
AND SOUTH ACROSS THE FCST AREA THIS EVENING. THE STORM ACTIVITY
SHOULD BE MOSTLY EAST OF THE FCST AREA BY 09Z WITH VFR THEREAFTER.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CLB
SHORT TERM...CLB
LONG TERM...MASEK
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
915 AM PDT FRI AUG 30 2013
.SYNOPSIS...A MOIST AND UNSTABLE ATMOSPHERE WILL ALLOW FOR SHOWERS
AND THUNDERSTORMS TO DEVELOP ACROSS THE AREA THROUGH THIS WEEKEND
WITH THE GREATEST CHANCES IN THE AFTERNOON AND EVENING HOURS. THE
PRIMARY HAZARD WITH THUNDERSTORMS WILL BE HEAVY RAINFALL THAT COULD
RESULT IN FLASH FLOODING. THUNDERSTORM CHANCES ARE EXPECTED TO
DECREASE SLIGHTLY FROM MONDAY ONWARD.
&&
.UPDATE...HAVE GONE AHEAD AND EXPANDED THE FLASH FLOOD WATCH TO
INCLUDE ALL OF SAN BERNARDINO COUNTY...THE SOUTHERN AREAS OF THE
COLORADO RIVER VALLEY AND THE WHITE MOUNTAINS OF INYO COUNTY. PLENTY
OF MOISTURE AVAILABLE WITH MOST OF THE PW SENSORS READING BETWEEN
1.75 AND 2.00 INCHES. SO FAR THIS MORNING SHOWERS AND THUNDERSTORMS
HAVE MAINLY BEEN CONFINED TO CENTRAL CLARK COUNTY WHERE THERE HAS
BEEN SOME ENHANCEMENT FROM A DISTURBANCE MOVING THROUGH ARIZONA. ONLY
ISOLATED ACTIVITY ELSEWHERE...BUT COVERAGE IS EXPECTED TO INCREASE
THIS AFTERNOON ESPECIALLY IN AREAS THAT ARE SEEING PLENTY OF
SUNSHINE THIS MORNING WHICH IS BASICALLY THE FAR WESTERN AND
NORTHERN AREAS OF THE CWA. AREAS UNDER THE CLOUD COVER COULD BE
DELAYED IN SEEING CONVECTION UNTIL LATER THIS AFTERNOON.
&&
.PREV DISCUSSION...
225 AM PDT FRI AUG 30 2013
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT. WHAT WAS LEFT OF THE
CONVECTIVE COMPLEX THAT DEVELOPED OVER MOHAVE COUNTY YESTERDAY
AFTERNOON WAS GONE, HOWEVER, THE FOCUS EARLY THIS MORNING ON RADAR
NOW SHIFTS TO ONGOING CONVECTION ACROSS YAVAPAI AND COCONINO
COUNTIES IN ARIZONA THAT WAS MOVING WESTWARD. THE HRRR MODEL DID NOT
DO A BAD JOB INDICATING THIS. THUS USING A BLEND OF THIS MODEL AND
THE LATEST RADAR TRENDS, I WENT AHEAD AND ADJUSTED UP POPS ACROSS
MUCH OF MOHAVE COUNTY FOR EARLY THIS MORNING AS IT APPEARS MUCH OF
THIS ACTIVITY SHOULD HAVE A CHANCE AT MAKING IT OVER THE BORDER INTO
OUR AREA. THE CLOUD COVER ASSOCIATED WITH THIS AS WELL AS WHAT
REMAINS FROM THE CLOUD COVER FROM THE CONVECTIVE COMPLEX THAT FORMED
ON THURSDAY AFTERNOON WILL PRESENT A BIT OF A CHALLENGE AS THIS
COULD LIMIT HEATING LATER TODAY OVER MOHAVE COUNTY WHICH MAY DELAY
OR INHIBIT CONVECTION ALTOGETHER IN THIS AREA.
AS FAR AS WHAT GOES ON THIS AFTERNOON AND EVENING, ACTIVITY WILL BE
DRIVEN BY HEATING WITH PERHAPS SOME HELP FROM A WEAK DISTURBANCE AND
INVERTED TROUGH IN THE MID-LEVELS WORKING NORTHWEST ACROSS SOCAL.
SERIOUS MOISTURE REMAINS IN PLACE ACROSS OUR ENTIRE AREA WITH
PWATS REMAINING IN THE UPPER REACHES OF CLIMATOLOGY FOR THIS AREA,
WITH VALUES AT OR ABOVE 1.75 INCHES FORECAST TO BE AROUND FROM I-15
ON SOUTH. FORECASTED 700-300 MB THETA E VALUES ARE SHOWN TO BE AT
LEAST 340 K ACROSS MOST OF AREA AS WELL. A LOOK AT INSTABILITY
PARAMETERS OFF THE MODELS SHOWS INSTABILITY IN PLACE ACROSS OUR
ENTIRE AREA, HOWEVER, BOTH THE GFS AND ECMWF SHOW THE GREATEST LI`S
OF -2 TO -4 ACROSS MOHAVE, CLARK AND SOUTHERN NYE COUNTIES. SO WHILE
WE COULD SEE SHOWERS AND THUNDERSTORMS ACROSS ANY PORTION OF THE
AREA THIS AFTERNOON AND EVENING, ODDS LOOK TO FAVOR AN AREA WITHIN
75 MILES ON EITHER SIDE OF A LINE FROM NEAR LONE PINE TO LAS VEGAS
TO KINGMAN AS THE MOST ACTIVE LOCATIONS. THUS I WENT AHEAD AND
ISSUED A FLASH FLOOD WATCH FOR MOST OF MOHAVE, ALL OF CLARK,
SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND ALL OF INYO COUNTY EXCEPT
THE WHITE MOUNTAINS FROM LATE THIS MORNING THROUGH THIS EVENING AS
WITH SO MUCH MOISTURE IN PLACE THE UNLOAD POTENTIAL WILL BE THERE IN
ANY STRONGER OR SLOWER MOVING STORMS. THE STEERING FLOW SHOWN BY THE
WRF AND GFS IS GENERALLY LIGHT AND FROM THE EAST TODAY, HOWEVER, BY
THIS EVENING IT DOES TAKE ON MORE OF A NORTHEAST COMPONENT. THUS,
THIS MAY BE ONE OF THOSE DAYS WHERE STORMS DO NOT AFFECT THE LAS
VEGAS VALLEY UNTIL LATER THIS EVENING AS WE MAY HAVE TO WAIT FOR
ACTIVITY TO HEAD IN FROM NORTHWEST ARIZONA, NORTHEAST CLARK COUNTY
OR SOUTHWEST UTAH. ACTIVITY SHOULD DECREASE LATER THIS EVENING,
HOWEVER, CLOUDS MAY NOT COMPLETELY CLEAR OUT TONIGHT, WHICH COULD
IMPACT THE FORECAST FOR SATURDAY.
AS FAR AS SATURDAY GOES, RIDGING ALOFT WILL REMAIN CENTERED OVER THE
SOUTHWEST AND THIS WILL KEEP OUR AREA IN A SOUTHEAST FLOW ALOFT
WHICH WILL ALLOW FOR WHATEVER MOISTURE IS IN PLACE TO REMAIN WITH THE
POTENTIAL FOR ADDITIONAL MOISTURE TO WORK INTO THE AREA. ACTIVITY ON
SATURDAY WILL DEPEND ON HEATING AND THUS IF WE START OFF TOO CLOUDY
THIS COULD LIMIT WHAT WE SEE WITH RESPECT TO SHOWER AND THUNDERSTORM
ACTIVITY. THE 00Z RUNS OF THE WRF, GFS, ECMWF AS WELL AS OUR LOCAL
HI-RESOLUTION MODELS FAVORED ACTIVITY DEVELOPING MAINLY ACROSS
SOUTHERN NEVADA, INYO AND NORTHERN AND CENTRAL MOHAVE COUNTY WITH
LESS ACTIVITY FURTHER SOUTH ON THE BACK SIDE OF THE INVERTED TROUGH.
FOR NOW WE HAVE HELD OFF ON ANY FLASH FLOOD WATCHES FOR SATURDAY,
BUT WITH SO MUCH MOISTURE IN PLACE, THE MAIN CONCERN IN STORMS AGAIN
WILL BE FLASH FLOODING.
TEMPS WILL CONTINUE TO REMAIN BELOW NORMAL FOR HIGHS AND AT OR ABOVE
NORMAL FOR LOWS. I USED A BLEND OF PERSISTENCE, THE SREF AND ECMWF
FOR MAX TEMPS AND CONTINUITY AND MOS GUIDANCE FOR MIN TEMPS.
DEWPOINTS WERE ADJUSTED UP SLIGHTLY OVER GUIDANCE GIVEN HOW MOIST WE
HAVE BEEN THE PAST 2 DAYS AND IT SEEMS MODELS HAVE BEEN A LITTLE LOW
ON PICKING UP ON THIS.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...MODELS IN PRETTY GOOD
AGREEMENT SUNDAY NIGHT THROUGH TUESDAY WITH A PRETTY GENERIC MONSOON
PATTERN AND NO SIGNIFICANT WAVES IMPACTING THE AREA. HIGH PRESSURE
IS FORECAST ROUGHLY OVER THE COLORADO AND NEW MEXICO BORDER AREA
WITH AN AREA OF LOW PRESSURE OFF THE PACIFIC NORTHWEST COAST.
SOUTHERLY FLOW OVER THE FORECAST AREA WILL KEEP MONSOON MOISTURE
AROUND WITH THE DEEPEST MOISTURE OVER THE EASTERN PORTION OF THE
FORECAST AREA AS IS TYPICAL WITH THIS PATTERN. AS A RESULT WE ARE
STILL LOOKING AT A CHANCE OF THUNDERSTORMS EAST WITH A SLIGHT CHANCE
WEST. MODELS DIFFER FOR WEDNESDAY THROUGH THURSDAY WITH THE GFS AND
TO A LESSER EXTENT THE GEM MOVING THE AREA OF LOW PRESSURE INLAND.
THIS WOULD BRING DRIER AIR INTO THE AREA FROM THE WEST. THE ECMWF IS
EXPANDING THE HIGH WESTWARD WHICH MAY KEEP A BIT MORE MOISTURE IN
PLACE BUT ALSO COULD LEAD TO WARMING AND SOME STABILIZING. BASICALLY
GOING WITH A BLEND...I MADE LITTLE CHANGE TO THE INHERITED GRIDS AND
KEPT AT LEAST A SLIGHT CHANCE OVER THE EASTERN TWO THIRDS OF THE
FORECAST AREA WHILE DRYING THE WEST BY THURSDAY. ALSO WENT WITH A
WARMING TREND AND ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY.
&&
.AVIATION...FOR MCCARRAN...
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...FOR MCCARRAN...SHRA/TSRA ARE EXPECTED TO BE AROUND THE
VALLEY MAINLY AFTER 18Z AND ESPECIALLY AFTER 20Z TODAY. SHRA AND
TSRA ARE EXPECTED TO MOVE IN A WEST TO SOUTHWEST DIRECTION THIS
AFTERNOON AND EVENING SO ACTIVITY THAT DEVELOPS OVER NW AZ OR
NORTHEAST CLARK COUNTY WILL NEED TO BE WATCHED - ESPECIALLY FOR ANY
OUTFLOW BOUNDARIES. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS BUT
OTHERWISE COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA OR
OUTFLOW BOUNDARIES WHICH COULD IMPACT AIRPORT CONFIGURATIONS. MAINLY
SCT-BKN CLOUDS AOA 10K-15K FEET WITH LOWER CIGS AND VSBY IN AND NEAR
ANY SHRA/TSRA. ACTIVITY SHOULD DECREASE BETWEEN 03Z AND 06Z SATURDAY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...SHRA/TSRA ARE EXPECTED ACROSS THE AREA AFTER 18Z AND
ESPECIALLY AFTER 20Z TODAY WITH THE GREATEST COVERAGE ACROSS MOHAVE,
CLARK, SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND INYO COUNTIES.
SHRA AND TSRA SHOULD FAVOR A SLOW WESTWARD MOVEMENT ACROSS MOST OF
THE AREA. SHRA/TSRA COULD REDUCE VSBY AND CIGS TO MVFR OR LOWER.
WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS THROUGH THIS EVENING BUT
COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA. SCT-BKN CLOUDS
AOA 10K-15K FEET AWAY FROM ANY SHRA/TSRA.
&&
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NVZ016>022.
AZ...FLASH FLOOD WATCH THROUGH THIS EVENING FOR AZZ001>003-036.
CA...FLASH FLOOD WATCH THROUGH THIS EVENING FOR CAZ519>527.
&&
$$
UPDATE...GORELOW
SHORT TERM/AVIATION...STACHELSKI
LONG TERM...HARRISON
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
354 PM EDT FRI AUG 30 2013
.SYNOPSIS...
THE LABOR DAY HOLIDAY WEEKEND WILL FEATURE WARM, HUMID AND
UNSETTLED WEATHER. SHOWERS AND THUNDERSTORMS ARE EXPECTED, BEING
MOST NUMEROUS SATURDAY AFTERNOON AND MONDAY. SOME OF THE
THUNDERSTORMS WILL BRING LOCALLY HEAVY DOWNPOURS. DRIER AND COOLER
WEATHER WILL RETURN FOR THE LATER HALF OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 330 PM EDT FRIDAY...STILL MONITORING THE APPROACH OF THE
CONVECTIVE CLUSTER MOVING ACROSS EASTERN ONTARIO AND THE GREAT
LAKES. RADAR SHOWING A FEW SMALL T-STORMS DEVELOPING BETWEEN
MASSENA AND OTTAWA, WHICH IS ALSO AN AREA THAT LOCAL ANALYSIS
INDICATES IS MOST UNSTABLE (CAPE APPROACHING 2000 J/KG AND LIFTED
INDEX VALUES LESS THAN -4). ELSEWHERE ACROSS THE REGION, CAPE
VALUES ARE A LITTLE LOWER (1000-1500 J/KG) ALONG WITH SUB-ZERO
LIFTED INDEX VALUES. HOWEVER, HAVEN`T YET SEEN SHOWER DEVELOPMENT.
LIKELY DUE TO MID-LEVEL DRY AIR. HOWEVER WATER VAPOR SHOWS
INCREASING MOISTURE MOVING IN, SO WOULD THINK WE SHOULD BE ABLE TO
POP A FEW INSTABILITY SHOWERS YET THIS AFTERNOON. HAVE KEPT IN
SOME SMALL POPS FOR THE EARLY EVENING FOR THE HIGHER TERRAIN.
OTHERWISE, THE FORECAST REALLY HINGES ON HOW THE CONVECTIVE
CLUSTER WILL EVOLVE TONIGHT AS IT MOVES INTO OUR AREA. MODELS
CONTINUE TO STRUGGLE WITH ALL THE DETAILS, AND THIS LEADS TO LOW
CONFIDENCE IN OVERALL FORECAST DETAILS. DO THINK THE 15Z HRRR HAD
A DECENT HANDLE ON THINGS AND SO HAVE TRIED TO PAINT ITS SCENARIO
IN. BASICALLY ITS FOR CONVECTION TO REACH THE ST LAWRENCE VALLEY
ABOUT 5PM AND WORK ITS WAY EASTWARD DURING THE MID EVENING.
HOWEVER SHORTWAVE SUPPORT APPEARS TO BE WEAKENING AND WITH LOSS OF
SUN, CONVECTION SHOULD DIMINISH AFTER SUNSET AS IT GETS TOWARD
VERMONT. BY MIDNIGHT EXPECT A BROKEN BAND OF SHOWERS -- PERHAPS AN
ISOLATED THUNDERSHOWER -- TO BE DISSIPATING ACROSS THE REGION.
NOT LOOKING FOR ANYTHING STRONG OR SEVERE OR MUCH IN THE WAY OF
HEAVY RAIN (OUTSIDE LOCALIZED DOWNPOUR). SEMI-BROADBRUSHED THE
GRIDDED FORECAST AS SPECIFIC LOCATION AND TIMING IS STILL TOO FUZZY.
SKIES OVERNIGHT WILL TREND MOSTLY CLOUDY. THE DEBRIS CLOUDS WILL
KEEP TEMPERATURES IN THE 60S FOR PRETTY MUCH EVERYONE. ADD ON
DEWPOINTS IN THE 60S, IT WILL BE RATHER MUGGY. THE CLOUDS SHOULD
PRECLUDE MUCH IN THE WAY OF ANY DENSE FOG FROM FORMING.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 330 PM EDT FRIDAY...SATURDAY THE REGION WILL BE SMACK DAB
IN THE CONTINUE WARM AIRMASS THAT WILL ALSO HAVE BECOME JUICED
FROM INCREASED MOISTURE. PRECIPITABLE WATER VALUES SHOULD BE UP
AROUND 1.75". A WEAK SURFACE BOUNDARY WILL BE STRUNG OUT JUST TO
OUR NORTH AND ADD IN OTHER WEAK BOUNDARIES FROM THE LEFTOVER
CONVECTIVE COMPLEX, WE WILL CERTAINLY HAVE PLENTY OF FOCUS
MECHANISMS FOR CONVECTIVE DEVELOPMENT. SHOULD BE ABLE TO SQUEAK
OUT A BIT OF SUNSHINE DURING THE MORNING, SO TEMPERATURES SHOULD
CLIMB QUICKLY THROUGH THE 70S AND PERHAPS INTO THE LOW 80S IN A
FEW SPOTS. THIS WILL PRODUCE ABUNDANT SURFACE BASED INSTABILITY
WITH CAPE VALUES OVER 1500 J/KG AND NEGATIVE LIFTED INDEX VALUES.
TOSS IN A LITTLE UPPER LEVEL ENERGY ZIPPING BY DURING MID- DAY,
AND ALL THE INGREDIENTS ARE IN PLACE FOR DEVELOPMENT OF WIDESPREAD
THUNDERSTORMS. WIND FIELDS ARE NOT ALL THAT STRONG, NOR IS THERE
MUCH SHEAR, SO THE STORMS WILL BE MORE DISORGANIZED BUT CAPABLE OF
PRODUCING SOME LOCALLY HEAVY DOWNPOURS. THIS COULD CAUSE A LITTLE
BIT OF MINOR FLOODING PROBLEMS.
SATURDAY NIGHT - STORMS SHOULD WIND DOWN IN THE EVENING, BUT LOTS
OF CLOUDS WILL REMAIN. ANOTHER WARM/MUGGY NIGHT WITH TEMPERATURES
IN THE MID-UPPER 60S FOR MOST OF US.
SUNDAY - LOOKS LIKE THE QUIETEST WEATHER FOR THE WEEKEND. THAT
SURFACE BOUNDARY SLIDES TO A POINT JUST SOUTH OF HERE, SO EVER SO
SLIGHTLY MORE STABLE CONDITIONS. NO IDENTIFIABLE TRIGGER ALOFT EITHER.
SO THAT SAID, SURFACE DEWPOINTS WILL STILL BE WELL INTO THE 60S,
SO ITS CONTINUED HUMID. SUNSHINE WILL AGAIN RESULT IN CONVECTION
STARTING TO BUBBLE UP BY MID-DAY. HAVE PAINTED INTO THE GRIDS
SCATTERED AFTERNOON SHOWERS/THUNDERSTORMS. COVERAGE WONT BE AS
STUPENDOUS AS ON SATURDAY AND MOST OF US MAY MANAGE TO STAY DRY.
SUNDAYS TEMPERATURES SHOULD RISE INTO THE LOWER TO PERHAPS 80S AS
SUNSHINE OFFSETS A SLIGHTLY COOLER AIRMASS (925MB TEMPERATURES
SHOULD BE 17-19C VS 20-22C THAT WERE OVERHEAD ON SATURDAY)
SUNDAY NIGHT - FAIRLY SIGNIFICANT UPPER TROUGH BEGINS TO DEVELOP
SOMEWHERE TO OUR WEST. SO ALTHOUGH ANY DAYTIME HEATING CONVECTION
SHOULD WIND DOWN IN THE EVENING, BY LATE NIGHT WE MAY SEE
SHOWERS/ISOLATED THUNDERSTORM RETURN TO THE AREA ALL THANKS TO
SOUTHERLY FLOW BECOMING DEEPER AND MORE ESTABLISHED. STILL A
SWEATY/WARM/MUGGY NIGHT WITH ALL THE CLOUDS AND HIGH DEWPOINTS.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 330 PM EDT FRIDAY...CHANGEABLE WEATHER EXPECTED THROUGH THE
EXTENDED FCST PERIOD AS THE PATTERN TRANSITIONS FROM A WARM AND
HUMID AIR MASS WITH WIDESPREAD SHOWERS AND TSTMS ON MONDAY TO
QUIET...DRY CONDITIONS AND BELOW AVERAGE TEMPERATURES BY THE END
OF THE WORK WEEK. IN FACT...CURRENT INDICATIONS ARE THAT THE FIRST
FROST OF THE SEASON IS POSSIBLE THURSDAY NIGHT OR FRIDAY NIGHT
ACROSS THE NRN ADIRONDACKS AND ESSEX COUNTY VT.
THE 12Z GFS REMAINS CONSISTENT WITH PREVIOUS RUNS SHOWING POTENTIAL
FOR WIDESPREAD SHOWERS AND THUNDERSTORMS MONDAY AFTN INTO MONDAY
EVENING. UPSTREAM 700-500MB SHORTWAVE TROUGH IS PROGGED TO AMPLIFY
ACROSS THE ERN GREAT LAKES REGION WITH INCREASING SWLY DEEP-LAYER
SHEAR TO 30-35 KTS ACROSS THE NORTH COUNTRY. PRE-EXISTING AIR MASS
SHOULD REMAIN MODERATELY HUMID WITH BOUNDARY LAYER DEWPOINTS IN THE
MID-UPR 60S AND HIGH TEMPS IN THE LOWER 80S IN VALLEY LOCATIONS.
THIS WILL CONTRIBUTE TO MODERATE SURFACE-BASED INSTABILITY WITH CAPE
VALUES 1000-2000 J/KG. MID-LEVEL LAPSE RATES AND LOW-LEVEL SHEAR NOT
GREAT...BUT OVERALL CONDITIONS FAVOR A FEW SVR STORMS MONDAY
AFTN/EARLY EVE WITH LOCALLY DAMAGING WINDS AND MARGINALLY SVR HAIL.
PW VALUES PEAK AROUND 1.70 INCHES 00Z TUESDAY AND SUPPORT LOCALLY
HEAVY DOWNPOURS WITH THE CONVECTIVE STORMS.
SURFACE TROUGH TRANSLATES EWD ACROSS THE AREA DURING MONDAY NIGHT
AND AS INSTABILITY DIMINISHING SHOULD SEE CONTINUED CHANCES FOR
SHOWER ACTIVITY...GRADUALLY LESSENING FROM WEST TO EAST OVERNIGHT.
NOT A FRONT...SO WITH LITTLE LOW-LEVEL CAA AND CONTINUED CLOUDS
SHOULD SEE LOWS MAINLY IN THE LOW-MID 60S.
LINGERING UPPER TROUGH ON TUESDAY...MAY GENERATE ISOLD/SCT SHOWERS
DURING THE AFTN HOURS. STILL WARM WITH HIGHS IN THE MID 70S TO NEAR
80...WITH SLIGHTLY LESS HUMIDITY. ONCE THE UPR TROUGH CLEARS THE
AREA LATE TUESDAY/TUESDAY NIGHT...SHOULD TRANSITION TO MOSTLY CLEAR
CONDITIONS. PROSPECTS GOOD FOR VALLEY FOG ON TUESDAY NIGHT/WED
MORNING AS A RESULT WITH LOWS IN THE 50S TO AROUND 60.
WED-FRI: WEDNESDAY...LOOKS DRY AND MOSTLY SUNNY WITH SW-NE ORIENTED
LOW-LEVEL RIDGE AXIS IN PLACE. SHOULD SEE NEAR SEASONABLE HIGHS IN
THE MID 70S. A COLD FRONT SLIDES SEWD ACROSS THE REGION ON
THURSDAY...AND SHOULD BE ASSOCIATED WITH A NARROW BAND OF SHOWERS
THURSDAY AFTN. SHOWING 30 POPS WITH THIS FEATURE FOR THURSDAY AFTN.
IN THE WAKE OF THE COLD FRONT...STRONGER CAA AND SHOULD SEE LOWS
DOWN INTO THE 40S THURSDAY NIGHT WITH HIGHS 62-68F ON FRIDAY. LARGER
SFC ANTICYCLONE BUILDS IN THU NIGHT THRU FRIDAY...AND OVERALL
PATTERN MAY ALLOW A FROST TO OCCUR THU NIGHT OR FRIDAY NIGHT IN THE
COLDER SPOTS WITHIN THE NRN ADIRONDACKS AND IN THE SHELTERED VALLEYS
OF THE NORTHEAST KINGDOM...ESPECIALLY IN ESSEX COUNTY VT. GOOD
POTENTIAL AGAIN FOR RIVER VALLEY FOG THURSDAY NIGHT AND FRIDAY
NIGHT BASED ON SYNOPTIC PATTERN AND ASSOCIATED CLIMATOLOGY.
&&
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
THROUGH 18Z SATURDAY...VFR AT ALL TERMINALS EARLY THIS AFTN AS
LOW CLOUDS HAVE MIXED OUT WITH DAYTIME HEATING. MAIN FOCUS NOW IS
ON UPSTREAM SHOWER ACTIVITY IN ADVANCE OF SHORTWAVE TROUGH
CROSSING LAKE HURON AND SERN ONTARIO AT 17Z. SCATTERED SHOWERS
WILL LIKELY IMPACT SLK/MSS BETWEEN 20-23Z...WITH A SLIGHT CHANCE
OF A TSTM. A BIT MORE DIFFICULT TO TELL IF TAF SITES FROM THE
CHAMPLAIN VALLEY EWD WILL BE AFFECTED...BUT CERTAINLY A CHANCE
22-02Z OF A SHOWER OR T-STORM WITH BRIEF MVFR CONDITIONS. HAVE
OPTED TO LEAVE OUT OF THE TAFS ATTM FROM PBG EASTWARD GIVEN
GREATER UNCERTAINTY. WINDS THRU THIS EVENING WILL BE FROM THE S-SW
AT 5-10 KTS...EXCEPT LOCALLY SE 10 KTS AT PBG WITH THE ONGOING
LAKE BREEZE. GREATER POTENTIAL FOR MID-LEVEL CLOUDS TONIGHT...SO
OPTED NOT TO INCLUDE FOG MENTION GIVING BKN-OVC100-120. ADDITIONAL
SHORTWAVE TROUGH AND ASSOCIATED SFC TROUGH MOVE THRU WITH
POTENTIAL FOR MORE WIDESPREAD SHOWERS AND TSTMS...ESPECIALLY
DURING SATURDAY AFTN. AT THIS POINT...INCLUDED MORNING MENTION OF
SHRA AT SLK/MSS...AS THEY WILL LIKELY SEE SOME ACTIVITY BEFORE THE
END OF THE TAF PERIOD. REMAINING SITES HAVE BEST CHANCE FOR
SHOWERS/TSTMS AFTER 18Z SATURDAY.
18Z SATURDAY THROUGH WEDNESDAY...SEVERAL ROUNDS OF SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE THRU THE AVIATION OUTLOOK PERIOD.
FIRST SFC/UPR TROUGH BRINGS WIDESPREAD SHOWERS AND T-STORMS DURING
SATURDAY AFTN AND EVENING. SHOULD SEE BRIEF INTERVALS OF MVFR AND
POSSIBLE BRIEF IFR AT ALL TAF LOCATIONS ASSOCIATED WITH THE
CONVECTIVE ACTIVITY. ANY PRECIPITATION SHOULD BE ISOLD
SUNDAY...WITH MAINLY VFR CONDITIONS DURING THE DAYLIGHT HRS. ANOTHER
STRONG UPR TROUGH APPROACHES THE REGION FROM THE WEST DURING
MONDAY/MONDAY NIGHT...LIKELY RESULTING IN NUMEROUS ADDITIONAL
SHOWERS AND TSTMS...ESPECIALLY MONDAY AFTN/EVE. DURING THESE
HIGHER THREAT PERIODS A FEW OF THE STORMS COULD TREND STRONG WITH
GUSTY WINDS/TURBULENCE/FRQ LIGHTNING. SCATTERED SHOWERS POSSIBLE
TUESDAY AND TRENDING DRIER FOR WEDNESDAY. PATCHY BR/FG AND ASSOC
MVFR/IFR CONDS ALSO POSSIBLE FROM 06-12Z EACH MORNING...WITH
HIGHEST CONFIDENCE AT MPV AND SLK.
&&
.EQUIPMENT...
AS OF 342 AM EDT FRIDAY...NOAA WEATHER RADIO STATION WXM 44...
BROADCASTING FROM THE TOP OF MOUNT ASCUTNEY VERMONT...REMAINS OFF
THE AIR UNTIL FURTHER NOTICE DUE TO A DAMAGED ANTENNA. REPLACEMENT
PARTS HAVE BEEN ORDERED...THOUGH IT STILL MAY BE UNTIL SEVERAL
WEEKS MORE BEFORE SERVICE IS RESTORED. WE APOLOGIZE FOR THE
INCONVENIENCE.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...NASH
NEAR TERM...NASH
SHORT TERM...NASH
LONG TERM...BANACOS
AVIATION...BANACOS
EQUIPMENT...WFO BTV
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
332 PM EDT FRI AUG 30 2013
.SYNOPSIS...
RAIN-FREE CONDITIONS ARE EXPECTED TODAY...ALONG WITH A
CONTINUATION OF WARM TEMPERATURES...AS A RIDGE OF HIGH PRESSURE
RESIDES ALONG THE EAST COAST. STARTING TONIGHT...AND THEN LASTING
THROUGH THE WEEKEND...OUR WEATHER WILL BECOME MORE UNSETTLED...AS
A SLOWLY APPROACHING FRONTAL BOUNDARY...ALONG WITH PASSING UPPER-
LEVEL DISTURBANCES...BRING PERIODIC BOUTS OF SHOWERS AND
THUNDERSTORMS. IT WILL ALSO REMAIN QUITE WARM...AND INCREASINGLY
MUGGY...THROUGHOUT THE HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1015 AM UPDATE...
FOG IS BURNING OFF AND IS EXPECTED TO RESULT IN PARTLY-MOSTLY
SUNNY SKIES THIS AFTN. THIS WL ALLOW TEMPS TO RISE CLOSE TO YDA`S
VALUES IN THE L/M 80S. WL KEEP AN EYE ON AREA OF SHOWERS MVNG
INTO LKS ERIE AND ONTARTIO AHD OF WK INITIAL S/WV. THIS WV WL
PROPAGATE INTO WRN PART OF CWA AFT 21Z AND LATEST HRRR BRINGS
CONVECTION INTO FA LATE THIS AFTN.
A STRONG S/WV IS NOW ROTATING ACRS LK SUPERIOR AND IS MAKING A
BEELINE FOR THE CWA FOR THE OVRNGT HRS. CURRENT THINKING IS THAT
WIND SHEAR VALUES WL INCREASE BTWN 03Z AND 06Z AND WL LOOK TO UP
POPS WITH THE AFTN PACKAGE. POTENTIAL EXISTS FOR STRONG WINDS AND
TORRENTIAL DOWNPOURS TONIGHT, ESPECIALLY FOR NRN ZONES. PW VALUES
INCREASE TO NEAR 1.60 INCHES WHICH IS 1-2 STANDARD DEVIATIONS ABV
NORMAL. H8 FLOW ONLY INCREASES TO NEAR 20KTS BY THIS TIME SO THINK
THE BIGGEST THREAT WL BE LOCALLY HVY RAINFALL AND PLAN TO UPDATE
HWO ACCORDINGLY.
PREV DISCO BLO...
4 AM FRI UPDATE... LWR STRATUS CLDS AND FOG HAVE BECOME WIDESPREAD
ONCE AGN EARLY THIS MRNG. MUCH LIKE YDY...GIVEN A MOIST BLYR
ENVIR...AND WEAK FLOW/VERT MIXING...IT WILL LIKELY TAKE A WHILE
FOR THE FOG TO LIFT...AND THE CLDS TO BREAK UP (13-15Z).
BY MIDDAY/EARLY AFTN...THE EARLIER MRNG STRATUS LYR SHOULD EVOLVE
INTO A SCT-BKN CU FIELD...WITH OCNL HIGHER-LVL CLOUD DEBRIS ALSO COMING
IN FROM THE NW (EMANATING FROM UPSTREAM CONVECTION).
OVERALL...PTLY SUNNY SEEMS LIKE A GOOD SKY COVER DESCRIPTOR. GIVEN
SIMILAR 925-850 MB TEMPS TO THU...AND ALSO A FAIRLY SIMILAR DEGREE
OF INSOLATION...MAX TEMPS SHOULD ONCE AGN RANGE FROM THE UPR 70S OVER
THE HIGHER TERRAIN OF THE CATSKILLS...TO THE UPR 80S IN PTNS OF
THE FINGER LKS RGN...AND OUR LAKE PLAIN CNTYS.
AS FAR AS CONVECTIVE POTENTIAL...WE THINK THE VAST MAJORITY OF THE DAY...IF
NOT THE ENTIRE DAY...WILL BE DEVOID OF ANY SHWRS/TSTMS. THE S/WV
WHICH PASSED THROUGH OUR RGN EARLY LAST EVE...IS NOW DOWN OVER
ERN VA...WITH DVM ALOFT/MID-LVL CAPPING EXPECTED TO REMAIN OVER
CNY/NE PA FOR A GOOD PTN OF THE DAY. THE NEXT S/WV UPSTREAM (SEEN
ON WATER VAPOR IMAGERY OVER NRN MI ATTM) IS NOT EXPECTED TO
APPROACH/BEGIN IMPACTING THE FA TIL ARND...OR AFTER 00Z. GIVEN THE
LIKELIHOOD OF 1000-1500 ML CAPES LTR TDY...WE CAN`T COMPLETELY
RULE OUT AN ISOLD TSTM OVER THE CATSKILLS/POCONOS...OR NEAR ANY
LAKE CONV BNDRYS DURG PEAK HEATING. HOWEVER..WE DON`T FEEL SUCH
COVERAGE/POTENTIAL (UNDER 10-15%) JUSTIFIES INCLUSION IN THE FCST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
420 AM FRI UPDATE... THE ABV REFERENCED S/WV OVER THE NRN LKS RGN
EARLY THIS MRNG...IS PROGGED TO TRACK NEAR LK ONT/UPSTATE NY
THIS EVE. FORCING FROM THIS FEATURE SHOULD CAUSE AN INCREASE IN
CONVECTIVE COVERAGE AFTER DARK....AND WE`LL THUS CARRY SCTD
SHWRS/TSTMS MOST AREAS...WITH A SMALL WINDOW FOR THE LIKELIHOOD OF
SUCH ACTIVITY IN OUR FAR NRN ZNS (03-09Z).
FOR THE NEXT COUPLE OF DAYS (SAT-SUN)...WE`RE EXPECTING A SCENARIO
FEATURING THE PASSAGE OF SVRL S/WVS (SOME PERHAPS CONVECTIVELY
INDUCED FROM UPSTREAM)...AND ALSO THE GRADUAL APPROACH OF A SFC FRONTAL
BNDRY...ULTIMATELY EXPECTED TO LIE JUST N/W OF THE CWA BY SAT
NGT/SUN. AFTER TNT`S ROUND OF SHWRS/TSTMS (FAIRLY HIGH CONFIDENCE
FCST)...THE TIMING OF SUBSEQUENT CONVECTIVE ROUNDS BCMS DIFFICULT
TO PIN DOWN THIS FAR OUT. THUS...FOR NOW...WE`LL SIMPLY MAINTAIN
CONTINUITY...AND RETAIN OUR FCST OF SCTD SHWRS/TSTMS...WITH THIS
ACTIVITY LIKELY TO PEAK DURG MAX HEATING/DESTABILIZATION EACH
AFTN/EARLY EVE. SOMEWHAT HIGHER POPS WILL BE INDICATED FOR NRN/WRN
PTNS OF THE FA (40-50%...VERSUS 20-30% DOWN OVER NE PA)...CLOSER
TO THE ABV MENTIONED FRNT. ALL OF THIS BEING SAID...THIS WEEKEND
WILL NOT BE A COMPLETE WASHOUT (SHWRS/TSTMS SCTD IN
NATURE)...WITH SIG RAIN-FREE PDS ANTICIPATED...IN BETWEEN
CONVECTIVE WAVES.
ALTHOUGH THE ENVIR IS LIKELY TO BECOME QUITE UNSTABLE BOTH SAT
AND SUN AFTNS (ML CAPES OF 1500-2500)...MODEL CONSENSUS SHOWS THE
DEEP-LYRD SHEAR TO BE FAIRLY WEAK (0-6 KM VALUES OF ONLY 15-20 KT
MUCH OF THE TIME). THUS...TSTMS SHOULD BE LARGELY NON-SVR (GARDEN
VARIETY)...WITH PERHAPS AN ISOLD PULSE-TYPE SVR STORM AT WORST.
WARM MUGGY CONDS WILL REMAIN AT PLAY THIS PD (DAYTIME HIGHS WELL
INTO THE 80S...AND NIGHT-TIME LOWS IN THE 60S-NEAR 70).
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
315 PM EDT UPDATE...
MADE MINOR ADJUSTMENTS TO PREVIOUS FORECASTS. MODELS THIS
AFTERNOON AGAIN ARE IN GOOD AGREEMENT WITH MID WEEK BUT DISAGREE
GREATLY IN THE EXTENDED. SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE THROUGH LATE TUESDAY NIGHT. WENT WITH MORE OF A ECMWF/CMC
BLEND. LEANED MORE TOWARDS ECMWF GUIDANCE SINCE THIS MODEL HAS
BEEN MOST CONSISTENT WITH PREVIOUS RUNS. TUESDAY A COLD FRONT WILL
PASS THROUGH THE REGION BRINGING CAA TO THE NE PA AND C NY. MODELS
STILL DIFFER GREATLY IN THE EXTENDED SO WENT WITH A CONSERVATIVE
PERSPECTIVE TO TEMPS WITH LOWS IN THE UPPER 40S TO LOW 50S AND
HIGHS IN THE UPPER 60S TO LOW 70S WED THRU FRIDAY.
PREVIOUS UPDAT...
430 AM FRI...
LITTLE TO CHANGE FROM THE PREVIOUS FORECAST FROM YESTERDAY
AFTERNOON. THE LONGER RANGE MODELS ARE IN GOOD AGREEMENT WITH A
TROF EARLY IN THE PERIOD ALONG WITH A SHOT OF COOLER WEATHER
THROUGH MID-WEEK. BY THURSDAY ANOTHER FRONT MOVES THROUGH THE AREA
WITH A CHANCE OF SHOWERS. IT WILL BE INTERESTING WITH RESPECT TO
WHAT HAPPENS WITH THIS SECOND TROF LATER IN THE WEEK. THE NEW 0Z
EURO IS MUCH SHARPER WITH THE TROF WITH 850 TEMPS AS CHILLY AS -2C
BY 12Z FRIDAY ACROSS NY STATE. MEANWHILE THE GFS HAS 850 TEMPS OF
+16C DURING THE SAME TIME. TALK ABOUT A DIFFERENCE! NO CLEAR SIGN
WHICH WAY TO LEAN AT THIS POINT WITH THE CANADIAN FAVORING THE
GFS...WHILE SOME OF THE GFS ENSEMBLES FAVORING THE EURO. WILL BE
FUN TO WATCH AS WE TURN TOWARD FALL. THE PREVIOUS AFD IS BELOW...
&&
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
145 PM EDT UPDATE...
THE FOG/LOW STRATUS DECK HAS FINALLY ERODED THIS AFTERNOON ACROSS
THE CWA. VFR CONDITIONS HAVE RETURNED AND EXPECT THESE CONDITIONS
TO PREVAIL THROUGH MUCH OF THE AFTERNOON. A LINE OF LIGHT SHOWERS
OVER WESTERN NEW YORK ARE SLOWLY MOVING EAST AND MAY AFFECT THE
TAF SITES. CONFIDENCE IS NOT HIGH ABOUT THIS LINE REMAINING
INTACT...THUS HAVE LEFT IT OUT OF THE TAF FOR NOW.
TONIGHT WILL BE A CHALLENGING FORECAST. DO NOT BELIEVE FOG WILL
DEVELOP LIKE PREVIOUS NIGHTS AS STRONG MID AND LOW LEVEL MIXING IS
PRESENT...BUT RAIN SHOWERS WILL MOVE INTO THE REGION FROM WEST TO
EAST LATE TONIGHT MAKING THE FORECAST DIFFICULT. THESE SHOWERS ARE
EXPECTED TO START OUT LIGHT WITH VFR CLOUD HEIGHTS THEN
TRANSITION TO MVFR AND BECOME HEAVY AT TIMES. SHOWERS ARE EXPECTED
TO CONTINUE THROUGH LATE AFTERNOON ON SATURDAY. EMBEDDED
THUNDERSTORMS ARE POSSIBLE WITH ISOLATED IFR CONDITIONS BUT
CONFIDENCE IS NOT HIGH WITH TIMING SO DECIDED TO LEAVE IT OUT.
OUTLOOK...
SAT-WED...POTENTIAL FOR MVFR IN SCTD SHRA/TSRAS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MLJ
NEAR TERM...MLJ/PVN
SHORT TERM...MLJ
LONG TERM...KAH/EH
AVIATION...KAH
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
209 PM EDT FRI AUG 30 2013
.SYNOPSIS...
RAIN-FREE CONDITIONS ARE EXPECTED TODAY...ALONG WITH A
CONTINUATION OF WARM TEMPERATURES...AS A RIDGE OF HIGH PRESSURE
RESIDES ALONG THE EAST COAST. STARTING TONIGHT...AND THEN LASTING
THROUGH THE WEEKEND...OUR WEATHER WILL BECOME MORE UNSETTLED...AS
A SLOWLY APPROACHING FRONTAL BOUNDARY...ALONG WITH PASSING UPPER-
LEVEL DISTURBANCES...BRING PERIODIC BOUTS OF SHOWERS AND
THUNDERSTORMS. IT WILL ALSO REMAIN QUITE WARM...AND INCREASINGLY
MUGGY...THROUGHOUT THE HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1015 AM UPDATE...
FOG IS BURNING OFF AND IS EXPECTED TO RESULT IN PARTLY-MOSTLY
SUNNY SKIES THIS AFTN. THIS WL ALLOW TEMPS TO RISE CLOSE TO YDA`S
VALUES IN THE L/M 80S. WL KEEP AN EYE ON AREA OF SHOWERS MVNG
INTO LKS ERIE AND ONTARTIO AHD OF WK INITIAL S/WV. THIS WV WL
PROPAGATE INTO WRN PART OF CWA AFT 21Z AND LATEST HRRR BRINGS
CONVECTION INTO FA LATE THIS AFTN.
A STRONG S/WV IS NOW ROTATING ACRS LK SUPERIOR AND IS MAKING A
BEELINE FOR THE CWA FOR THE OVRNGT HRS. CURRENT THINKING IS THAT
WIND SHEAR VALUES WL INCREASE BTWN 03Z AND 06Z AND WL LOOK TO UP
POPS WITH THE AFTN PACKAGE. POTENTIAL EXISTS FOR STRONG WINDS AND
TORRENTIAL DOWNPOURS TONIGHT, ESPECIALLY FOR NRN ZONES. PW VALUES
INCREASE TO NEAR 1.60 INCHES WHICH IS 1-2 STANDARD DEVIATIONS ABV
NORMAL. H8 FLOW ONLY INCREASES TO NEAR 20KTS BY THIS TIME SO THINK
THE BIGGEST THREAT WL BE LOCALLY HVY RAINFALL AND PLAN TO UPDATE
HWO ACCORDINGLY.
PREV DISCO BLO...
4 AM FRI UPDATE... LWR STRATUS CLDS AND FOG HAVE BECOME WIDESPREAD
ONCE AGN EARLY THIS MRNG. MUCH LIKE YDY...GIVEN A MOIST BLYR
ENVIR...AND WEAK FLOW/VERT MIXING...IT WILL LIKELY TAKE A WHILE
FOR THE FOG TO LIFT...AND THE CLDS TO BREAK UP (13-15Z).
BY MIDDAY/EARLY AFTN...THE EARLIER MRNG STRATUS LYR SHOULD EVOLVE
INTO A SCT-BKN CU FIELD...WITH OCNL HIGHER-LVL CLOUD DEBRIS ALSO COMING
IN FROM THE NW (EMANATING FROM UPSTREAM CONVECTION).
OVERALL...PTLY SUNNY SEEMS LIKE A GOOD SKY COVER DESCRIPTOR. GIVEN
SIMILAR 925-850 MB TEMPS TO THU...AND ALSO A FAIRLY SIMILAR DEGREE
OF INSOLATION...MAX TEMPS SHOULD ONCE AGN RANGE FROM THE UPR 70S OVER
THE HIGHER TERRAIN OF THE CATSKILLS...TO THE UPR 80S IN PTNS OF
THE FINGER LKS RGN...AND OUR LAKE PLAIN CNTYS.
AS FAR AS CONVECTIVE POTENTIAL...WE THINK THE VAST MAJORITY OF THE DAY...IF
NOT THE ENTIRE DAY...WILL BE DEVOID OF ANY SHWRS/TSTMS. THE S/WV
WHICH PASSED THROUGH OUR RGN EARLY LAST EVE...IS NOW DOWN OVER
ERN VA...WITH DVM ALOFT/MID-LVL CAPPING EXPECTED TO REMAIN OVER
CNY/NE PA FOR A GOOD PTN OF THE DAY. THE NEXT S/WV UPSTREAM (SEEN
ON WATER VAPOR IMAGERY OVER NRN MI ATTM) IS NOT EXPECTED TO
APPROACH/BEGIN IMPACTING THE FA TIL ARND...OR AFTER 00Z. GIVEN THE
LIKELIHOOD OF 1000-1500 ML CAPES LTR TDY...WE CAN`T COMPLETELY
RULE OUT AN ISOLD TSTM OVER THE CATSKILLS/POCONOS...OR NEAR ANY
LAKE CONV BNDRYS DURG PEAK HEATING. HOWEVER..WE DON`T FEEL SUCH
COVERAGE/POTENTIAL (UNDER 10-15%) JUSTIFIES INCLUSION IN THE FCST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
420 AM FRI UPDATE... THE ABV REFERENCED S/WV OVER THE NRN LKS RGN
EARLY THIS MRNG...IS PROGGED TO TRACK NEAR LK ONT/UPSTATE NY
THIS EVE. FORCING FROM THIS FEATURE SHOULD CAUSE AN INCREASE IN
CONVECTIVE COVERAGE AFTER DARK....AND WE`LL THUS CARRY SCTD
SHWRS/TSTMS MOST AREAS...WITH A SMALL WINDOW FOR THE LIKELIHOOD OF
SUCH ACTIVITY IN OUR FAR NRN ZNS (03-09Z).
FOR THE NEXT COUPLE OF DAYS (SAT-SUN)...WE`RE EXPECTING A SCENARIO
FEATURING THE PASSAGE OF SVRL S/WVS (SOME PERHAPS CONVECTIVELY
INDUCED FROM UPSTREAM)...AND ALSO THE GRADUAL APPROACH OF A SFC FRONTAL
BNDRY...ULTIMATELY EXPECTED TO LIE JUST N/W OF THE CWA BY SAT
NGT/SUN. AFTER TNT`S ROUND OF SHWRS/TSTMS (FAIRLY HIGH CONFIDENCE
FCST)...THE TIMING OF SUBSEQUENT CONVECTIVE ROUNDS BCMS DIFFICULT
TO PIN DOWN THIS FAR OUT. THUS...FOR NOW...WE`LL SIMPLY MAINTAIN
CONTINUITY...AND RETAIN OUR FCST OF SCTD SHWRS/TSTMS...WITH THIS
ACTIVITY LIKELY TO PEAK DURG MAX HEATING/DESTABILIZATION EACH
AFTN/EARLY EVE. SOMEWHAT HIGHER POPS WILL BE INDICATED FOR NRN/WRN
PTNS OF THE FA (40-50%...VERSUS 20-30% DOWN OVER NE PA)...CLOSER
TO THE ABV MENTIONED FRNT. ALL OF THIS BEING SAID...THIS WEEKEND
WILL NOT BE A COMPLETE WASHOUT (SHWRS/TSTMS SCTD IN
NATURE)...WITH SIG RAIN-FREE PDS ANTICIPATED...IN BETWEEN
CONVECTIVE WAVES.
ALTHOUGH THE ENVIR IS LIKELY TO BECOME QUITE UNSTABLE BOTH SAT
AND SUN AFTNS (ML CAPES OF 1500-2500)...MODEL CONSENSUS SHOWS THE
DEEP-LYRD SHEAR TO BE FAIRLY WEAK (0-6 KM VALUES OF ONLY 15-20 KT
MUCH OF THE TIME). THUS...TSTMS SHOULD BE LARGELY NON-SVR (GARDEN
VARIETY)...WITH PERHAPS AN ISOLD PULSE-TYPE SVR STORM AT WORST.
WARM MUGGY CONDS WILL REMAIN AT PLAY THIS PD (DAYTIME HIGHS WELL
INTO THE 80S...AND NIGHT-TIME LOWS IN THE 60S-NEAR 70).
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
430 AM FRI UPDATE... LITTLE TO CHANGE FROM THE PREVIOUS FORECAST
FROM YESTERDAY AFTERNOON. THE LONGER RANGE MODELS ARE IN GOOD
AGREEMENT WITH A TROF EARLY IN THE PERIOD ALONG WITH A SHOT OF
COOLER WEATHER THROUGH MID-WEEK. BY THURSDAY ANOTHER FRONT MOVES
THROUGH THE AREA WITH A CHANCE OF SHOWERS. IT WILL BE INTERESTING
WITH RESPECT TO WHAT HAPPENS WITH THIS SECOND TROF LATER IN THE
WEEK. THE NEW 0Z EURO IS MUCH SHARPER WITH THE TROF WITH 850 TEMPS
AS CHILLY AS -2C BY 12Z FRIDAY ACROSS NY STATE. MEANWHILE THE GFS
HAS 850 TEMPS OF +16C DURING THE SAME TIME. TALK ABOUT A
DIFFERENCE! NO CLEAR SIGN WHICH WAY TO LEAN AT THIS POINT WITH THE
CANADIAN FAVORING THE GFS...WHILE SOME OF THE GFS ENSEMBLES
FAVORING THE EURO. WILL BE FUN TO WATCH AS WE TURN TOWARD FALL.
THE PREVIOUS AFD IS BELOW...
PREV DISC... 3 PM EDT UPDATE... MADE MINOR ADJUSTMENTS TO THE
PREVIOUS FORECAST. A STRONG UPPER LEVEL TROUGH DIPS SOUTH OUT OF
CANADA ON SUNDAY ACROSS THE UPPER GREAT PLAINS AND THEN MOVES
EASTWARD TOWARDS THE GREAT LAKES ON MONDAY. THE INFLUENCE FROM
THIS SYSTEM WILL BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS
MONDAY NIGHT THROUGH WEDNESDAY. THE UPPER LOW WILL CONTINUE TO
MIGRATE EASTWARD AND MOVE OFF THE EAST COAST BY WEDNESDAY NIGHT.
THE ECMWF IS SLIGHTLY STRONGER THAN THE GFS...HOWEVER BOTH ARE IN
PRETTY GOOD AGREEMENT ON THE PLACEMENT OF THE TRACK OF UPPER LOW.
THURSDAY ANOTHER UPPER LOW WILL MOVE NORTH OF THE REGION POSSIBLY
BRINGING A COLD FRONT TO THE AREA.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
145 PM EDT UPDATE...
THE FOG/LOW STRATUS DECK HAS FINALLY ERODED THIS AFTERNOON ACROSS
THE CWA. VFR CONDITIONS HAVE RETURNED AND EXPECT THESE CONDITIONS
TO PREVAIL THROUGH MUCH OF THE AFTERNOON. A LINE OF LIGHT SHOWERS
OVER WESTERN NEW YORK ARE SLOWLY MOVING EAST AND MAY AFFECT THE
TAF SITES. CONFIDENCE IS NOT HIGH ABOUT THIS LINE REMAINING
INTACT...THUS HAVE LEFT IT OUT OF THE TAF FOR NOW.
TONIGHT WILL BE A CHALLENGING FORECAST. DO NOT BELIEVE FOG WILL
DEVELOP LIKE PREVIOUS NIGHTS AS STRONG MID AND LOW LEVEL MIXING IS
PRESENT...BUT RAIN SHOWERS WILL MOVE INTO THE REGION FROM WEST TO
EAST LATE TONIGHT MAKING THE FORECAST DIFFICULT. THESE SHOWERS ARE
EXPECTED TO START OUT LIGHT WITH VFR CLOUD HEIGHTS THEN
TRANSITION TO MVFR AND BECOME HEAVY AT TIMES. SHOWERS ARE EXPECTED
TO CONTINUE THROUGH LATE AFTERNOON ON SATURDAY. EMBEDDED
THUNDERSTORMS ARE POSSIBLE WITH ISOLATED IFR CONDITIONS BUT
CONFIDENCE IS NOT HIGH WITH TIMING SO DECIDED TO LEAVE IT OUT.
OUTLOOK...
SAT-WED...POTENTIAL FOR MVFR IN SCTD SHRA/TSRAS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MLJ
NEAR TERM...MLJ/PVN
SHORT TERM...MLJ
LONG TERM...HEDEN/KAH
AVIATION...KAH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1258 PM CDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 1258 PM CDT FRI AUG 30 2013
NO SIGNIFICANT CHANGES WITH THIS FORECAST UPDATE. THE THINKING
REMAINS UNCHANGED FROM THE 1021 AM CDT UPDATE BELOW REGARDING
EXPECTED CONVECTION. THIS IS CONFIRMED BY THE 16 UTC HRRR AND 12
UTC 4 KM WRF.
UPDATE ISSUED AT 1021 AM CDT FRI AUG 30 2013
CANCELLED THE DENSE FOG ADVISORY FOR CENTRAL NORTH DAKOTA AS THE
15 UTC OBSERVATIONS AND WEBCAMS SHOW ALL FOG HAS BURNED OFF ACROSS
THE AREA.
THE FOCUS REMAINS ON SEVERE CONVECTIVE DEVELOPMENT LATE THIS
AFTERNOON AND INTO THE EVENING. THE 13 UTC HRRR CONTINUES THE
TREND SUPPORTED BY THE 00 UTC 4 KM WRF AND SPC SSEO OF INITIATING
CONVECTION ALONG THE PRE-FRONTAL TROUGH BETWEEN HIGHWAY 85 AND 83
BETWEEN 20-22 UTC. -10 TO -30 HAIL CAPE VALUES OF 700-900 J/KG
WITH DEEP LAYER SHEAR OF 40-50 KTS SUGGESTS LARGE HAIL WILL BE A
PRIMARY THREAT...ALONG WITH DAMAGING WINDS WITH DOWNDRAFT CAPE
VALUES AOA 1000 J/KG. LOCALLY HEAVY RAINFALL IS ALSO EXPECTED WITH
PWATS NEAR 1.50 INCHES. WHILE THE TORNADIC THREAT IS LOW...ANY
SUPERCELLS THAT CAN INTERACT WITH THE TROUGH MAY PRESENT A
LOCALIZED THREAT FOR TORNADOES.
UPDATE ISSUED AT 714 AM CDT FRI AUG 30 2013
QUICK UPDATE TO ISSUE A DENSE FOG ADVISORY FOR MUCH OF CENTRAL
NORTH DAKOTA GIVEN THE 12 UTC FOG CHANNEL...SURFACE OBSERVATIONS
AND WEBCAMS.
UPDATE ISSUED AT 624 AM CDT FRI AUG 30 2013
UPDATE TO ADD AREAS OF DENSE FOG FROM HARVEY THROUGH
JAMESTOWN...AND PATCHY DENSE FOG WESTWARD THROUGH THE HIGHWAY 83
CORRIDOR. DENSE FOG NOT CONSIDERED WIDESPREAD ENOUGH FOR ADVISORY
AT THIS TIME. OTHERWISE...CURRENT FORECAST IN GOOD SHAPE. SCATTERED
THUNDERSTORMS EXPECTED WEST THIS AFTERNOON...SPREADING EAST
TONIGHT...SOME POSSIBLY SEVERE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 335 AM CDT FRI AUG 30 2013
CURRENTLY...SURFACE HIGH PRESSURE EXTENDED FROM MANITOBA SOUTHWARD
ACROSS CENTRAL NORTH DAKOTA INTO WESTERN SOUTH DAKOTA. A SURFACE
FRONT EXTENDED FROM A LOW OVER SOUTHERN ALBERTA TO CENTRAL MONTANA.
AT UPPER LEVELS...A SHORTWAVE EXTENDED FROM NORTHERN
ALBERTA/SASKATCHEWAN SOUTHWARD ACROSS CENTRAL MONTANA. THIS UPPER
LEVEL SHORTWAVE FEATURE WAS ASSOCIATED WITH A SCATTERED LINE OF
SHOWERS AND THUNDERSTORMS MOVING EASTWARD ACROSS CENTRAL MONTANA AND
SOUTH CENTRAL SASKATCHEWAN.
THE LATEST MODEL RUNS DEPICT THE UPPER LEVEL SHORTWAVE LIFTING
NORTHEASTWARD THIS MORNING SUCH THAT THE STRONGER FORCING REMAINS
NORTH OF THE CANADIAN BORDER AFTER DAYBREAK. HOWEVER THIS AFTERNOON
THE SHORTWAVE GAINS STRENGTH AND DEVELOPS SOUTHWARD ACROSS
WESTERN/CENTRAL NORTH DAKOTA...MOVING EAST INTO THE RED RIVER VALLEY
LATE THIS EVENING. IN RESPONSE...THE SURFACE FRONT IS FORECAST TO
MOVE INTO WESTERN NORTH DAKOTA LATE THIS AFTERNOON AND PROGRESS
EASTWARD SLOWLY...BEFORE STALLING OVER CENTRAL NORTH DAKOTA.
FORECAST CAPE VALUES OF 1000 TO OVER 2000 ARE FORECAST OVER WESTERN
AND CENTRAL NORTH DAKOTA THIS AFTERNOON...COMBINED WITH 0-6KM BULK
SHEAR VALUES OF 35 TO 50 KNOTS. THE LARGE AMOUNT OF AVAILABLE
CONVECTIVE ENERGY...ALONG WITH THE STRONG SHEAR...SUGGESTS
THUNDERSTORMS COULD REACH SEVERE LIMITS. THUS THE STORM PREDICTION
CENTER HAS PLACED MOST OF THE FORECAST AREA IS IN A SLIGHT RISK OF
SEVERE THUNDERSTORMS FOR THIS AFTERNOON AND TONIGHT.
ANOTHER VERY WARM DAY TODAY WITH HIGHS PROGGED TO BE IN THE MID TO
UPPER 80S FROM THE NORTH THROUGH THE JAMES RIVER VALLEY...AND INTO
THE LOWER 90S ALONG AND SOUTH/WEST OF THE MISSOURI RIVER. LOWS
TONIGHT IN THE 60S.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 335 AM CDT FRI AUG 30 2013
ON SATURDAY...THUNDERSTORMS ARE EXPECTED TO LINGER...ESPECIALLY
SOUTHEAST IN THE VICINITY OF A COLD FRONT. THE EXTREME SOUTHEAST
WILL LIKELY BE ON THE FRINGE OF THE MOST FAVORABLE AREA FOR
ISOLATED SEVERE STORMS. DRIER AIR WILL PUSH INTO THE
SOUTHWEST...DROPPING DEWPOINTS INTO THE 40S AND MINIMUM AFTERNOON
RH BETWEEN 25-30 PERCENT. THE GRASSLAND FIRE DANGER INDEX IS
FORECAST TO BE IN THE HIGH CATEGORY. THE CHANCE OF ADDITIONAL RAIN
BEYOND SATURDAY IS LOW. SUNDAY WILL LIKELY BE THE COOLEST DAY OF
THE WEEK...WITH HIGHS MAINLY IN THE 70S. A WARMING TREND WILL
BEGIN ON LABOR DAY...WITH HIGHS FROM THE UPPER 70S EAST TO MID 80S WEST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1258 PM CDT FRI AUG 30 2013
VFR CONDITIONS OUTSIDE OF THUNDERSTORMS ARE EXPECTED FOR THE
UPCOMING 18 UTC TAFS. SCATTERED THUNDERSTORMS ARE EXPECTED TO
INITIATE BETWEEN THE WESTERN TAF SITES OF KISN/KDIK AND THE
CENTRAL SITES OF KMOT/KBIS BETWEEN 20-22 UTC...AND MOVE EAST
THROUGH THE EVENING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
335 PM EDT FRI AUG 30 2013
.SYNOPSIS...
LOW PRESSURE MOVING ACROSS THE CENTRAL GREAT LAKES WILL DRAG A
COLD FRONT ACROSS THE AREA LATE TONIGHT AND SATURDAY. THE FRONT
WILL STALL ACROSS CENTRAL OHIO SATURDAY NIGHT. A STRONGER COLD
FRONT WILL FOLLOW ON MONDAY USHERING COOLER AIR FOR MID WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
FOR THE EARLY EVENING WILL HAVE SLIGHT CHANCE POPS NWRN PA. RADAR
HAS CONTINUED TO SHOW SMALL RAIN SHOWERS IMPACTING ERIE COUNTY FAR
NORTHEAST AND THIS COULD CONTINUE INTO THE EVENING. MOST AREAS
WILL REMAIN DRY HOWEVER. ELSEWHERE EXPECT PARTLY CLOUDY SKIES
THROUGH THE EVENING. OVERNIGHT A COLD FRONT TO OUR NORTH WILL
CONTINUE DROPPING SOUTH TOWARD THE AREA. CONVECTION IS OCCURRING
ON THE LINE WITH ONE DEVELOPING CLUSTER IN SERN WI WITH A BROKEN
LINE ACROSS NORTHERN LOWER MI. HRRR BRINGS THE WI CLUSTER INTO NRN
INDIANA BY 03Z WHILE THE ACTIVITY ACROSS NRN LOWER MI WEAKENS AND
BECOMES INCREASINGLY ISOLATED IN SERN LOWER MI AND ONTARIO JUST
NORTH OF THE LAKE. WILL BRING CHANCE POPS TO NWRN OHIO AND THE
LAKE MAINLY AFTER MIDNIGHT WITH POPS INCREASING TO CHANCE ACROSS
THE REMAINDER OF THE AREA TIER BETWEEN 06Z AND 12Z. FOLLOWED SREF
TIMING BUT GUIDANCE POPS WERE MUCH HIGHER THAN THE GFS MOS SO DID
SCALE BACK TOWARD THE GFS MOS CHANCE POPS. TEMPS AGAIN MILD WITH
LOWS IN THE UPPER 60S.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
WILL CONTINUE WITH CHANCE POPS THROUGH THE DAY AS THE WEAK COLD
FRONT SLOWLY SAGS SOUTH THROUGH THE AREA. BEST CHANCE LIKELY
SOUTHEAST COUNTIES GIVEN THAT THE FRONT WILL BE MOVING INTO THAT
AREA DURING THE AFTERNOON HOURS. SATURDAY NIGHT THE FRONT WILL
LIKELY STALL JUST TO OUR SOUTH AS LOW PRESSURE MOVES ALONG IT WEST
OF THE AREA. BOTH THE NAM AND GFS INDICATE MOISTURE INCREASES
AGAIN FROM THE SOUTHWEST AS THE FRONT WAFFLES BACK TOWARD OR INTO
THE AREA. BROUGHT CHANCE POPS BACK AFTER MIDNIGHT WEST AFTER
HAVING DRIED IT OUT FOR THE EVENING. SUNDAY THROUGH MONDAY MODELS
CONTINUE TO INCREASE MOISTURE ACROSS THE AREA AHEAD OF ANOTHER
APPROACHING COLD FRONT. THE FRONT WILL MOVE THROUGH THE AREA
MONDAY AND WITH FORECAST CAPES FROM 2-3000J/KG FOR THE AFTERNOON
TSTMS COULD GET STRONG. WILL CONTINUE TO WATCH SEVERE POTENTIAL
BUT FOR NOW WILL HAVE HIGH CHANCE TO LIKELY POPS THROUGH THE DAY.
TUESDAY NIGHT WILL ALLOW WESTERN COUNTIES TO DRY OUT AS HIGH
PRESSURE AND DRIER AIR MOVE IN. WILL KEEP CHANCE POPS FOR SHOWERS
IN THE EAST GIVEN THE MOISTURE AND THE FACT THAT COOLER AIR WILL
BE MOVING ACROSS THE LAKE. HIGHS ABOVE NORMAL MUCH OF THE PERIOD.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BUILD OVER THE AREA ON TUESDAY AS THE UPPER LEVEL
TROUGH AXIS SHIFTS EAST OF THE GREAT LAKES. THE AIRMASS WILL FEEL
NOTICEABLY DIFFERENT WITH DECREASING HUMIDITY AND TEMPERATURES
DROPPING BACK TO BELOW NORMAL VALUES. EXPECTING SCT-BKN CLOUDS WITH
THE GREATEST COVERAGE IN NE OH/NW PA. HIGHS WILL TOP OUT IN THE LOW
70S IN OHIO...STRUGGLING TO GET OUT OF THE 60S IN NW PA.
HIGH PRESSURE WILL BUILD SOUTHEAST ACROSS THE REGION ON
WEDNESDAY...SHIFTING TO THE OHIO VALLEY ON THURSDAY. TEMPERATURES
WILL REBOUND SEVERAL DEGREES WITH MOSTLY SUNNY SKIES AND GOOD
INSOLATION ON WEDNESDAY.
12Z MODEL SUITE HAS COME INTO BETTER AGREEMENT WITH THE HANDLING OF
THE NEXT FRONT ON THURSDAY. THE 00Z ECMWF WHICH WAS FASTER AND
STRONGER WITH THE NEXT COLD FRONT HAS SLOWED DOWN WITH THE 12Z RUN
AND TRENDED TOWARDS A WEAKER FRONT. THIS IS CLOSER TO THE SOLUTION
OFFERED BY THE GFS SO WILL LEAN THE FORECAST TOWARDS JUST ANOTHER
MODEST DROP IN TEMPERATURES TOWARDS THE END OF THE WEEK INSTEAD OF
THE COLDER SOLUTION.
&&
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL CONTINUE THROUGH ABOUT 04Z WHEN HZ/BR WILL START
TO DEVELOP WITH HIGH BOUNDARY LAYER MOISTURE IN PLACE. LOW PRESSURE WILL
MOVE FROM THE UPPER GREAT LAKES TO NEAR LAKE ONTARIO OVERNIGHT.
SHOWERS AND A FEW THUNDERSTORMS WILL OCCUR AHEAD OF THE ASSOCIATED
FRONT THAT WILL PUSH SOUTH OVER THE AREA LATE TONIGHT INTO SATURDAY
MORNING. FOR NOW HAVE PUT VCSH INTO ALL SITES BUT HAVE NOT INCLUDED
THUNDERSTORMS GIVEN THE UNCERTAINTY IN COVERAGE. A SCT-BKN MVFR
CLOUD DECK WILL LIKELY DEVELOP BEHIND THE FRONT ON SATURDAY MORNING
WITH SOME POTENTIAL FOR IFR CLOUDS/VISIBILITY.
OUTLOOK...NON VFR LIKELY INLAND LOCATIONS EACH MORNING IN PATCHY
FOG. NON VFR IN SCATTERED SHOWERS/THUNDERSTORMS SATURDAY THROUGH
MONDAY.
&&
.MARINE...
A LIGHT SOUTHWESTERLY FLOW WITH SOME DEGREE OF A LAKE BREEZE ON THE
EASTERN HALF OF THE LAKE IS IN PLACE TODAY. WINDS WILL INCREASE TO
10 TO 15 KNOTS AHEAD OF A COLD FRONT THAT WILL PUSH SOUTH ACROSS THE
LAKE LATE TONIGHT INTO SATURDAY MORNING. SCATTERED SHOWERS AND
THUNDERSTORMS ARE ALSO EXPECTED AHEAD OF THE FRONT. WINDS WILL SHIFT
TO THE NORTHWEST BEHIND THE FRONT ON SATURDAY BUT ARE NOT EXPECTED
TO BE MORE THAN 5 TO 15 KNOTS AS THE FRONT STALLS OVER CENTRAL
OHIO.
WIND WILL SHIFT AROUND TO THE SOUTH ON SUNDAY AS A WARM FRONT PUSHES
BACK NORTH OVER THE LAKE. THERE WILL BE A CHANCE OF THUNDERSTORMS
SUNDAY...INCREASING SUNDAY NIGHT INTO MONDAY AS LOW PRESSURE
APPROACHES THE GREAT LAKES FROM THE WEST. THIS SYSTEM WILL PULL A
STRONGER COLD FRONT ACROSS THE LAKE ON MONDAY WITH NORTHWESTERLY
WINDS INCREASING TO 10 TO 20 KNOTS DURING THE AFTERNOON. THE
NORTHWESTERLY FLOW WILL LEAD TO WAVES BUILDING TO 2 TO 4 FEET ON
MONDAY NIGHT AND TUESDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...TK
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
212 PM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST
EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND
WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE
NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE
RETURNS ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM...I WILL ISSUE A QUICK UPDATE TO INCREASE SKY COVER AND
REDUCE POPS OVER THE NEXT COUPLE OF HOURS. TEMPERATURES UNDER THE
CLOUD COVER HAS MANAGED TO AGREE FAIRLY WELL WITH THE FORECAST...BUT
I WILL MAKE SEVERAL MINOR ADJUSTMENTS.
AS OF NOON...SATELLITE AND SFC OBS INDICATED THAT A WEAK WEDGE OF
STABLE AIR HAS SETTLED ACROSS THE WESTERN CAROLINAS. HOWEVER...A
BAND UNSTABLE AIR REMAINS POOLS ACROSS THE UPPER SAVANNAH RIVER
VALLEY AND WESTERN NC MTNS THIS MORNING. LLVL ENE WINDS COUPLED WITH
WEST WINDS ALOFT HAS RESULTED IN VERY SLOW STORM MOTIONS THIS
MORNING. AN ISOLATED SHOWER HAS REMAINED OVER OCONEE COUNTY THIS
MORNING...RESULTING IN MULTIPLE FLOODED ROADS. HOWEVER...NAM
INDICATES THAT LLVL WINDS WILL VEER THIS MORNING...LIKELY RESULTING
IN THE SHOWER TO DRIFT SE INTO MORE STABLE AIR. THE REST OF THE DAY
SHOULD FEATURE WEDGE-LIKE CLOUD PATTER ACROSS THE EAST FACING
SLOPES...NE GA...AND THE SC UPSTATE THROUGH THIS AFTERNOON. I WILL
UPDATE THE FORECAST TO LOWER TEMPS UNDER THE CLOUD COVER. POPS WILL
HIGHLIGHT LATE AFTERNOON CONVECTION ACROSS THE HIGH TERRAIN.
630 AM UPDATE...REGARDING PRECIP IN THE SAVANNAH RIVER VALLEY...THE
CURRENT TRENDS SUGGEST THE ACTIVITY WILL DIMINISH AS INSTABILITY
BOTTOMS OUT AT DIURNAL MINIMUM. HOWEVER RAP CAPE TRENDS BEGIN
RAMPING BACK UP OVER THE NEXT COUPLE HOURS. LAPSE RATES AND PROG
SOUNDINGS STILL LOOK UNIMPRESSIVE TODAY AWAY FROM THE BLUE
RIDGE...BUT THESE CELLS ARE IN AN AREA FAVORED BY THE OVERNIGHT NAM
RUNS AS WELL AS THE RAP SO I HAVE MADE A GRADUAL TRANSITION OF POPS
FROM THE WRN UPSTATE UP TO THE MTNS.
AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION
WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL
LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE
REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK
OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE
RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY
CORRESPONDINGLY GREATER.
UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER
THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS
THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO
MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW
CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS
CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST
CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER
THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 215 PM FRI...UPPER HEIGHTS ARE FORECAST TO GRADUALLY FALL
ACROSS THE EASTERN U.S LATE IN THE WEEKEND INTO THE NEW WORK WEEK AS
AN UPPER TROUGH DIGS OVER THE GREAT LAKES. IN THE DEVELOPING NW
FLOW...A WEAK SHORT WAVE WILL MOVE EAST OF THE AREA SAT
NIGHT...WHILE A SECOND WAVE IS FORECAST TO REACH THE AREA LATE
SUNDAY AFTERNOON...AND THEN ANOTHER LATE MON. IN THE BOUNDARY
LAYER...WEAK S/SW FLOW WILL KEEP COPIOUS MOISTURE OVER THE AREA WITH
PW VALUES IN THE 1.75-2 INCH RANGE. THIS COMBINED WITH MODERATE
INSTABILITY WILL LEAD TO DIURNAL CONVECTION BOTH SUN AND MON
AFTERNOONS....WITH THE USUAL DECREASE IN COVERAGE OVERNIGHT.
COVERAGE BOTH DAYS WILL FAVOR THE MOUNTAINS WITH LOWER...BUT STILL
SCATTERED COVERAGE OVER THE PIEDMONT. HIGHS WILL BE CLOSE TO NORMAL
BOTH DAYS WITH LOWS ABOUT 5 DEGREES ABOVE NORMAL.
A WEAK COLD FRONT WILL APPROACH THE AREA LATE MONDAY. FORECAST
SOUNDINGS INDICATE BETTER INSTABILITY MONDAY AFTERNOON...AND A
LITTLE BETTER SHEAR WHICH WILL GIVE A LOW END SEVERE THREAT.
HOWEVER...IT LOOKS LIKE THE LARGEST THREAT IS FOR ISOLATED FLASH
FLOODING BOTH SUN AND MON DUE TO SLOW MOVING STORMS.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 200 PM FRI...THE EXTENDED PERIOD WILL FEATURE AN UPPER TROUGH
AMPLIFYING OVER THE EASTERN U.S. AND AN UPPER HIGH OVER THE WEST. AT
THE SURFACE...A COLD FRONT IS FORECAST TO MOVE THROUGH THE AREA MON
NIGHT. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT TUE NIGHT INTO THU.
A SECONDARY COLD FRONT WILL REACH THE REGION ON FRI.
THE NW FLOW ALOFT WILL PROMOTE GENERALLY DRY CONDITIONS. THE
EXCEPTION IS ON TUE WHEN SOME LINGERING INSTABILITY BEHIND THE COLD
FRONT MAY TRIGGER SOME SCATTERED THUNDERSTORMS. THE FRI FRONT WILL
HAVE LITTLE MOISTURE TO WORK WITH...SO POPS WILL REMAIN LOW. TEMPS
WILL BE SLIGHTLY BELOW NORMAL THROUGH THE PERIOD.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE...A U SHAPED BAND OF MVFR CLOUDS REMAINS
ACROSS THE EASTERN SLOPES OF THE MTNS AND THE UPSTATE OF SC THIS
AFTERNOON. RECENT SATELLITE TRENDS SHOWS SLOW ADVECTION OF DRIER AIR
SW ACROSS THE NC/SC LINE NEAR THE I-77 CORRIDOR. DIURNAL HEATING AND
INCREASING DRY AIR SHOULD RESULT IN PREVAILING VFR BASED CLOUDS BY
19Z...THEN REMAIN VFR THROUGH THIS EVENING. THE CHALLENGE OVERNIGHT
WILL BE THE POTENTIAL FOR ANOTHER ROUND OF RESTRICTIVE CEILINGS.
MODELS HAVE DONE A POOR JOB WITH THIS MORNINGS CLOUD COVER. GIVEN
THE LINGERING LLVL MOISTURE ACROSS THE SAVANNAH RIVER
VALLEY...COMBINED WITH VEERING LLVL FLOW...MOISTURE SHOULD INCREASE
ACROSS THE REGION OVERNIGHT. I WILL INDICATE THE REDEVELOPMENT OF
MVFR CEILINGS BY 7Z...PERSISTING THROUGH MID MORNING SAT. VFR
CONDITIONS ARE EXPECTED FROM 15Z ON. CLT MAY REMAIN VFR UNTIL
MORNING HEATING DEVELOPS MVFR CLOUDS. CONVECTION SHOULD REMAIN WEST
OF THE TERMINALS THROUGH 18Z SAT.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY
THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN
VALLEYS AND WHERE RAIN FELL THE DAY BEFORE.
CONFIDENCE TABLE...
18-24Z 00-06Z 06-12Z 12-18Z
KCLT HIGH 100% HIGH 100% HIGH 98% HIGH 82%
KGSP HIGH 100% HIGH 100% HIGH 91% MED 60%
KAVL HIGH 85% HIGH 81% LOW 38% LOW 59%
KHKY HIGH 100% HIGH 100% HIGH 83% MED 69%
KGMU HIGH 100% HIGH 100% HIGH 91% MED 64%
KAND HIGH 94% HIGH 100% MED 69% LOW 53%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JOH
NEAR TERM...NED
SHORT TERM...LG
LONG TERM...LG
AVIATION...NED
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1212 PM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST
EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND
WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE
NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE
RETURNS ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS NOON...SATELLITE AND SFC OBS INDICATED THAT A WEAK WEDGE OF
STABLE AIR HAS SETTLED ACROSS THE WESTERN CAROLINAS. HOWEVER...A
BAND UNSTABLE AIR REMAINS POOLS ACROSS THE UPPER SAVANNAH RIVER
VALLEY AND WESTERN NC MTNS THIS MORNING. LLVL ENE WINDS COUPLED WITH
WEST WINDS ALOFT HAS RESULTED IN VERY SLOW STORM MOTIONS THIS
MORNING. AN ISOLATED SHOWER HAS REMAINED OVER OCONEE COUNTY THIS
MORNING...RESULTING IN MULTIPLE FLOODED ROADS. HOWEVER...NAM
INDICATES THAT LLVL WINDS WILL VEER THIS MORNING...LIKELY RESULTING
IN THE SHOWER TO DRIFT SE INTO MORE STABLE AIR. THE REST OF THE DAY
SHOULD FEATURE WEDGE-LIKE CLOUD PATTER ACROSS THE EAST FACING
SLOPES...NE GA...AND THE SC UPSTATE THROUGH THIS AFTERNOON. I WILL
UPDATE THE FORECAST TO LOWER TEMPS UNDER THE CLOUD COVER. POPS WILL
HIGHLIGHT LATE AFTERNOON CONVECTION ACROSS THE HIGH TERRAIN.
630 AM UPDATE...REGARDING PRECIP IN THE SAVANNAH RIVER VALLEY...THE
CURRENT TRENDS SUGGEST THE ACTIVITY WILL DIMINISH AS INSTABILITY
BOTTOMS OUT AT DIURNAL MINIMUM. HOWEVER RAP CAPE TRENDS BEGIN
RAMPING BACK UP OVER THE NEXT COUPLE HOURS. LAPSE RATES AND PROG
SOUNDINGS STILL LOOK UNIMPRESSIVE TODAY AWAY FROM THE BLUE
RIDGE...BUT THESE CELLS ARE IN AN AREA FAVORED BY THE OVERNIGHT NAM
RUNS AS WELL AS THE RAP SO I HAVE MADE A GRADUAL TRANSITION OF POPS
FROM THE WRN UPSTATE UP TO THE MTNS.
AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION
WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL
LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE
REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK
OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE
RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY
CORRESPONDINGLY GREATER.
UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER
THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS
THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO
MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW
CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS
CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST
CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER
THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 215 PM FRI...UPPER HEIGHTS ARE FORECAST TO GRADUALLY FALL
ACROSS THE EASTERN U.S LATE IN THE WEEKEND INTO THE NEW WORK WEEK AS
AN UPPER TROUGH DIGS OVER THE GREAT LAKES. IN THE DEVELOPING NW
FLOW...A WEAK SHORT WAVE WILL MOVE EAST OF THE AREA SAT
NIGHT...WHILE A SECOND WAVE IS FORECAST TO REACH THE AREA LATE
SUNDAY AFTERNOON...AND THEN ANOTHER LATE MON. IN THE BOUNDARY
LAYER...WEAK S/SW FLOW WILL KEEP COPIOUS MOISTURE OVER THE AREA WITH
PW VALUES IN THE 1.75-2 INCH RANGE. THIS COMBINED WITH MODERATE
INSTABILITY WILL LEAD TO DIURNAL CONVECTION BOTH SUN AND MON
AFTERNOONS....WITH THE USUAL DECREASE IN COVERAGE OVERNIGHT.
COVERAGE BOTH DAYS WILL FAVOR THE MTNS WITH LOWER...BUT STILL SCT
COVERAGE OVER THE PIEDMONT. HIGHS WILL BE CLOSE TO NORMAL BOTH DAYS
WITH LOWS ABOUT 5 DEGREES ABOVE NORMAL.
A WEAK COLD FRONT WILL APPROACH THE AREA LATE MONDAY. FORECAST
SOUNDINGS INDICATE BETTER INSTABILITY MONDAY AFTERNOON...AND A
LITTLE BETTER SHEAR WHICH WILL GIVE A LOW END SEVERE THREAT.
HOWEVER...IT LOOKS LIKE THE LARGEST THREAT IS FOR ISOLATED FLASH
FLOODIND BOTH SUN AND MON DUE TO SLOW MOVING STORMS.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 200 PM FRI...THE EXTENDED PERIOD WILL FEATURE AN UPPER TROUGH
AMPLIFYING OVER THE EASTERN U.S. AND AN UPPER HIGH OVER THE WEST. AT
THE SURFACE...A COLD FRONT IS FORECAST TO MOVE THROUGH THE AREA MON
NIGHT. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT WED INTO THU.
A SECONDARY COLD FRONT WILL REACH THE REGION ON FRI.
THE NW FLOW ALOFT WILL PROMOTE GENERALLY DRY CONDITIONS. THE
EXCEPTION IS ON TUE WHEN SOME LINGERING INSTABILITY BEHIND THE COLD
FRONT TUE MAY TRIGGER SOME SCATTERED THUNDERSTORMS. THE FRI FRONT
WILL HAVE LITTLE MOISTURE TO WORK WITH...SO POPS WILL REMAIN LOW.
TEMPS WILL BE SLIGHTLY BELOW NORMAL THROUGH THE PERIOD.
&&
.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
AT KCLT...SOME UNCERTAINTY AS TO WHETHER LOW MVFR STRATOCU WILL
REACH THE FIELD IN EASTERLY FLOW INTO THE PIEDMONT EARLY THIS
MORNING. WILL MAINTAIN SCT010 FOR FIRST HOUR. OTHERWISE VFR CUMULUS
WILL BE THE DOMINANT CLOUDS BY MID MORNING. LIGHT ENE WINDS SHOULD
VEER TO SE BY AFTN PER CONSENSUS OF LATEST GUIDANCE. THE SELY FLOW
WITH ATLANTIC FETCH MAY CAUSE LOW STRATUS TO MOVE IN TONIGHT SIMILAR
TO WHAT IS HAPPENING THIS MORNING. GUIDANCE HAS HANDLED THIS
MORNING/S CIGS POORLY SO WILL KEEP TONIGHT VFR FOR NOW.
ELSEWHERE...PATCHY STRATOCU WILL PLAGUE THE TAF SITES EARLY THIS
MORNING. THE CLOUDS ARE MOSTLY LOW VFR TO MVFR BUT OBS SUGGEST SOME
BASES MAY BE AT IFR LEVEL. SHRA IN THE SAVANNAH RIVER VALLEY WILL
CAUSE EVEN MORE RESTRICTIVE CONDITIONS EARLY TODAY AS WELL. AWAY
FROM PRECIP CIGS SHOULD EASILY BE ABLE TO MIX UP TO VFR BY MID
MORNING. ISOLD TO WIDELY SCT CONVECTION MAY DEVELOP BY MIDDAY NEAR
THE BLUE RIDGE BUT CHCS TOO LOW FOR A TAF MENTION ATTM. LIGHT NE TO
ENE WINDS WILL VEER TO GENERALLY SE BY AFTERNOON AND REMAIN THERE
INTO THE EVENING. THE SE WINDS WILL BRING IN ATLANTIC MOISTURE AND
MAY ALLOW CIGS TO LOWER ONCE AGAIN TONIGHT...WITH GUIDANCE ALSO
SUPPORTING MVFR FOG ACRS MUCH OF THE AREA.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY
THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN
VALLEYS AND WHERE RAIN FELL THE DAY BEFORE.
CONFIDENCE TABLE...
16-22Z 22-04Z 04-10Z 10-16Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 87%
KGSP HIGH 100% HIGH 100% HIGH 88% HIGH 95%
KAVL HIGH 99% HIGH 100% MED 74% HIGH 87%
KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 100% HIGH 100% HIGH 100% MED 79%
KAND HIGH 94% HIGH 100% HIGH 94% MED 79%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...NED
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
324 PM CDT FRI AUG 30 2013
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
DESTABILIZATION OCCURRING THIS AFTERNOON ACROSS THE WESTERN
DAKOTAS WITH MESOANALYSIS INDICATING AROUND 2000 J/KG MLCAPE.
SHEAR VALUES RANGE FROM AROUND 35 TO 40 KNOTS OVER WESTERN SD. A
SEVERE STORM IS AFFECTING THE BLACK HILLS AT THIS TIME...WITH VIS
SATELLITE IMAGERY SHOWING THE BEGINNINGS OF A CU FIELD EXTENDING
NORTHWARD INTO DICKINSON ND. HI RES MODELS DO SHOW ISOLD/WDLY SCT
CONVECTION OCCURRING OVER THE NEXT FEW HOURS AND LASTING INTO THE
EVENING HOURS...SOME OF WHICH MAY AFFECT THE FAR WESTERN CWA.
LATEST HRRR RUN HAS THE CONVECTION OVER THE BLACK HILLS NAILED
RIGHT NOW AND SHOWS SMALL BUT POTENT CELLS DEVELOPING ALONG THE
CURRENT CU FIELD OVER THE NEXT COUPLE HOURS...THEN PUSHES THINGS
INTO CORSON/DEWEY COUNTIES. NOT SURE AREAL COVERAGE WILL BE AS
GREAT AS THE HRRR...BUT IN SOME FORM OR ANOTHER...DO EXPECT ISOLD
TO WDLY SCT STORMS OVER THE NEXT FEW HOURS. SVR WATCH 505 WAS
RECENTLY ISSUED TO COVER THIS THREAT. WITH THE LACK OF ANY
APPRECIABLE LOW LEVEL JET OVERNIGHT...DO NOT EXPECT THIS ACTIVITY
TO SURVIVE MUCH PAST THE MISSOURI RIVER AND SHOULD WANE WITH THE
LOSS OF DAYTIME HEATING.
FOCUS WILL THEN TURN TO THE ADVANCING COLD FRONT ON SATURDAY.
FRONT WILL SET UP ACROSS THE EASTERN CWA BY PEAK HEATING...WITH
MODERATE INSTABILITY AND SHEAR DEVELOPING. ALTHOUGH BEST UPPER
LEVEL SUPPORT IS NORTH OF THE REGION...CONVERGENCE ALONG THE SHARP
FRONTAL BOUNDARY ALONG WITH SUFFICIENT LOW LEVEL MOISTURE AND
STEEP LAPSE RATES IS EXPECTED TO LEAD TO MID/LATE AFTERNOON
THUNDERSTORM DEVELOPMENT ALONG THE FRONT. SPEED OF THE FRONT WILL
BE KEY IN DETERMINING BEST CHANCE FOR STORMS. GIVEN PLACEMENT OF
THE FRONT BY AFTERNOON...CONVECTIVE INITIATION COULD OCCUR BETWEEN
THE JAMES VALLEY AND I-29...WITH MORE CONSOLIDATION/BETTER STORM
CHANCES CLOSER TO I-29 AND POINTS EAST BY LATE AFTERNOON AND INTO
THE EVENING. DAY TWO SLIGHT RISK IS NOW INCLUDING EASTERN PORTIONS
OF THE FORECAST AREA.
BEHIND THIS FRONT WILL BE MUCH COOLER AIR...WITH HIGHS ON SUNDAY
EXPECTED TO DROP BACK INTO THE 70S FOR MOST AREAS. SFC HIGH WILL
BUILD SOUTH INTO THE AREA SUNDAY NIGHT...AND WITH THE COOLER AND
DRIER AIR MASS IN PLACE...LOWS BY MONDAY MORNING COULD ACTUALLY
DIP INTO THE UPPER 40S.
.LONG TERM...MONDAY THROUGH FRIDAY
THE LONG TERM LOOKS TO REMAIN ON THE DRY SIDE WITH UPPER LEVEL
RIDGING AND SUBSIDENT FLOW DOMINATING THE WEATHER. THE MODELS SHOW
THE UPPER LEVEL RIDGE AXIS OUT WEST TO BEGIN THE LONG TERM PUSHING
EAST THROUGH FRIDAY OVER OUR REGION. ANY SHORT WAVES MOVING OVER
THE RIDGE SHOULD BE MOISTURE STARVED WITH ONLY SOME CLOUDS MOVING
IN. AFTER A COOLER DAY ON MONDAY...WARMER AIR WILL RETURN FOR
TUESDAY AND REMAIN THROUGH FRIDAY. SHOULD HAVE MID 70S EAST ON
MONDAY WARMING TO THE 80S TO THE LOWER 90S ACROSS ALL OF THE CWA
THROUGH THE REST OF THE WEEK.
&&
.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
VFR CONDITIONS ARE EXPECTED AT ALL TAF SITES THROUGH TONIGHT AND
SATURDAY MORNING. A COLD FRONT COMING ACROSS THE REGION LATER
TONIGHT AND SATURDAY WILL BRING SOME SHOWERS AND STORMS ALONG IT
WHICH MAY AFFECT THE TERMINALS. WILL WATCH FOR DEVELOPMENT.
ALSO...EXPECT SOME FOG TO FORM AT ATY LATER TONIGHT WITH THE LIGHT
WINDS AND CLEAR SKIES. LIGHT FOG MAY ALSO BE POSSIBLE AT ABR.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
SHORT TERM...TMT
LONG TERM...MOHR
AVIATION...MOHR
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
153 PM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE OVER THE MID ATLANTIC TODAY WILL SHIFT OFFSHORE
BY THIS EVENING. A WARM FRONT ENTERS THE MOUNTAINS
SATURDAY...FOLLOWED BY A COLD FRONT ARRIVING SOMETIME MONDAY.
DURING THIS PERIOD...SHOWER AND THUNDERSTORM CHANCES REMAIN.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 148 PM EDT FRIDAY...
WEAK INSITU WEDGE WILL MOVE OFF SHORE THROUGH THIS EVENING. AS
THIS WEDGE MOVES OUT OF THE AREA...ANY LINGERING LOW STRATUS DECK
WILL ALSO EXIT THE AREA. LIGHT SOUTHERLY FLOW WILL THEN BRING WARM
HUMID AIR BACK INTO THE REGION OVER THE NEXT 24 HOURS. HRRR AND
06Z RNK WRF PICKING UP ON A THETA-E BOUNDARY ACROSS THE AREA FROM
SUMMERS COUNTY WV TO THE WESTERN PART OF GRAYSON COUNTY NC. THE
LOCATION OF THIS BOUNDARY AND POINTS WEST WILL BE THE AREA THAT
SHOULD SEE ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS THIS
AFTERNOON. ISOLATED SEVERE THREAT IS POSSIBLE WITH DRY AIR ABOVE
700 MB. HOWEVER...SATURATED SOUNDING BELOW 700 MB MAY ONLY
GENERATE LOW TOP CONVECTION WITH THE POTENTIAL FOR SOME STRONGER
STORMS TO PRODUCE HEAVY RAIN. STORMS THAT DEVELOP WITH THE HEATING
OF THE DAY WILL BE SLOW MOVING. THEREFORE...THE BIGGEST THREAT
WILL BE LOCALIZED FLOODING...ESPECIALLY IN AREAS THAT HAVE SEEN
RAIN THE PAST COUPLE OF DAYS.
BREAKS IN THE CLOUDS TODAY WILL ALLOW TEMPERATURES TO MAX OUT
NEAR NORMAL...WIDESPREAD 80S. DEW POINTS WILL REMAIN HIGH WITH
READINGS IN THE MID 60S TO LOWER 70S.
TONIGHT...THERE SHOULD BE A QUICKER DROP OFF IN PRECIP THAN THIS
PAST EVENING AS THE HIGHER THETA-E AIR MOVES INTO TN/KY. WITH
CLEARING SKIES AND LIGHT WINDS...SHOULD SEE PATCHY FOG OVER MOST OF
THE AREA...ESPECIALLY RIVER VALLEYS. LOWS ARE GOING TO BE IN THE 60S
STILL.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
AS OF 400 AM EDT FRIDAY...
HIGH PRESSURE WILL CONTINUE TO MOVE OFF THE ATLANTIC COAST
SATURDAY MORNING...WITH A WEAK WARM FRONT CROSSING OUR AREA FROM
THE SOUTHWEST. WILL SEE ANOTHER ROUND OF SPOTTY SHOWERS AND
THUNDERSTORMS DEVELOP WITH DAYTIME HEATING...MAINLY ACROSS THE
MOUNTAINS STARTING IN EARLY AFTERNOON...AND THEN SPILLING OVER
INTO THE PIEDMONTS DURING THE EARLY EVENING AS WINDS AND
ATMOSPHERIC MIXING BEGINS TO WEAKEN. A LEE SIDE TROUGH SETTING UP
ACROSS THE PIEDMONTS WILL CAUSE WINDS ACROSS THE MOUNTAINS TO
SHIFT MORE WESTERLY AND THEREFORE DOWNSLOPE...WHICH WILL HELP
LIMIT INSTABILITY SOMEWHAT...BUT STILL CANNOT RULE OUT A FEW
STRONG STORMS. THINK THE BIGGER ISSUE TO KEEP WATCH FOR WILL BE
THE POTENTIAL FOR LOCALLY HEAVY RAIN DUE TO ABUNDANT TROPICAL
MOISTURE...AND SLOW MOVEMENT OF STORMS DUE TO LIGHT UPPER LEVEL
WINDS.
LOOKING AT A SIMILAR WEATHER PATTERN FOR SUNDAY...WITH SHOWERS
AND THUNDERSTORMS DEVELOPING IN THE WEST DURING EARLY AFTERNOON
AND SPREADING EAST LATER IN THE DAY. HOWEVER...BELIEVE COVERAGE OF
RAINFALL WILL BE GREATER AS AN UPPER LEVEL TROUGH APPROACHES FROM
THE GREAT LAKES...FURTHER DESTABILIZING THE ATMOSPHERE.
ON MONDAY...A DEEP LOW PRESSURE SYSTEM WILL CROSS THE GREAT
LAKES...DRAGGING A COLD FRONT RAPIDLY EASTWARD FROM THE
MISSISSIPPI RIVER VALLEY. WILL AGAIN SEE SCATTERED SHOWERS AND
THUNDERSTORMS DEVELOP...WHICH WILL LINGER INTO LATE EVENING AS THE
COLD FRONT MAKES ITS WAY ACROSS OUR AREA AFTER SUNSET. THIS COLD
FRONT WILL USHER IN A MUCH DRIER CANADIAN AIRMASS...WHICH WILL
BRING AND END TO ALL BUT LINGERING SHOWERS ACROSS OUR WESTERN
RIDGELINES BY TUESDAY MORNING.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 246 AM EDT FRIDAY...
BY TUESDAY...THE COLD FRONT WILL BE SITUATED ALONG THE EAST
COAST...WITH HIGH PRESSURE BUILDING INTO THE REGION FOR THE
REMAINDER OF THE WORK WEEK. TEMPERATURES IN THIS HIGH PRESSURE
AIRMASS WILL RUN COOLER THAN NORMAL FOR OUR AREA...RANGING FROM
THE MID 70S IN THE WEST TO LOWER 80S IN THE EAST FOR DAILY HIGHS.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 127 PM EDT FRIDAY...
AREAS EAST OF THE BLUE RIDGE STILL UNDER THE INFLUENCE OF A WEAK
INSITU WEDGE. MVFR VISIBILITIES WERE SLOW TO LIFT AND SO IS THE
MVFR CEILINGS. ENOUGH MIXING AND SUNSHINE WILL EVENTUALLY
LIFT/ERODE THESE CLOUDS TO VFR THIS AFTERNOON. WEDGE MAY LINGER
ACROSS THE SOUTHERN HALF OF RNK CWA OVERNIGHT. THIS MAY BRING A
RETURN TO SUB- MVFR FOG AND CLOUDS TO AREAS ALONG THE VA/NC BORDER
(DAN) POSSIBLY AGAIN TO ROA/LYH. IF ENOUGH CLEARING TAKES PLACE
OVERNIGHT...RADIATIONAL IFR OR LOWER VALLEY FOG LIKELY AT LWB/BCB
EARLY SATURDAY MORNING.
RAIN CHANCE THIS AFTERNOON ARE BETTER FOCUS WEST OF THE THETA-E
BOUNDARY ACROSS THE MOUNTAINS. SCATTERED SLOW MOVING STORMS ARE
POSSIBLE AT BLF THROUGH THIS EVENING. ISOLATED SHOWERS AND
THUNDERSTORMS ARE POSSIBLE AT LWB/BCB LATE THIS AFTERNOON AND
EVENING. AREAL COVERAGE SPOTTY THEREFORE WILL ONLY HAVE VICINITY
SHOWERS AT EACH OF THESE AIRPORTS THIS AFTERNOON.
MORE AREAL COVERAGE OF SHOWERS AND STORMS EXPECTED
SATURDAY...ESPECIALLY ACROSS THE MOUNTAINS. THE AREA WILL BE IN A
WARM SECTOR WITH THE DAILY THREAT FOR SHOWERS/STORMS SUNDAY. A
COLD FRONT WILL WORK ACROSS BY LATE MONDAY WITH DRIER AIR MOVING
IN BY THE MIDDLE OF NEXT WEEK. OVERALL OUTSIDE OF LATE NIGHT
FOG/STRATUS AND SUB VFR CONDITIONS IN SHOWERS/STORMS WILL BE
SEEING VFR SAT-TUE.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WP
NEAR TERM...RCS/WP
SHORT TERM...NF
LONG TERM...RCS
AVIATION...JH/KK/RCS/WP
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
354 PM CDT FRI AUG 30 2013
.VERY SHORT TERM...TONIGHT AND SATURDAY.
TONIGHT - CONFIDENCE...MEDIUM
PLENTY OF CAPE POOLING AHEAD OF SOUTHWARD MOVING FRONTAL BOUNDARY.
STORMS ARE ORGAN ZING AS BEST AS THEY CAN GIVEN THE LACK OF DECENT
0-6KM SHEAR AND SUSPECT MID LEVEL LAPSE RATES. HOWEVER PLENTY OF
CAPE IN THE LOW LEVELS WITH GOOD LOW LEVEL LAPSE RATES WITH
SURFACE/925 CONVERGENCE ALLOWING FOR SOME STRONGER WINDS AND HAIL.
WATER VAPOR/RUC COMBO DOES SHOW A WEAK UPSTREAM WAVE RIDING IN
FROM SRN MN AND NRN IA. HRRR SHOWING STORMS CLEARING THE FAR SOUTH
AROUND 00Z OR SO. HOWEVER 4KM WRF-SPC AND 12Z ECMWF LINGER PRECIP
ACROSS PORTIONS OF SC WI DEEPER INTO THE EVENING. BASED ON FRONTAL
PROGRESSION WILL BANK ON A QUICKER EXIT OF PRECIP BASED ON OTHER
MODELS. SO FRONTAL BOUNDARY EXITS TO THE SOUTH THIS EVENING TAKING
ANY LINGERING STORMS WITH IT. WILL RETAIN HEAT ADVISORY FOR SOUTHERN
TIER ONLY AS I-94 CORRIDOR AFFECTED BY OUTFLOW AND STORMS.
SURFACE/925 COOL AIR ADVECTION THEN TAKES HOLD. NOT SO MUCH UP TO
850 MILLIBARS...BUT FROM 925 AND ON DOWN PRETTY STRONG SIGNAL AND
THIS IS PLAUSIBLE GIVEN CONDITIONS UPSTREAM IN NORTHERN WISCONSIN.
EXPECTING COOLER AND DRIER DEW POINTS TO ADVECT INTO THE AREA WITH
THE EVOLVING POST-FRONTAL NORTH WINDS. LOW LEVEL WIND FLOW/DEGREE OF
MIXING SUGGESTS THE EVOLUTION OF DENSE FOG NOT LIKELY. LOOKS MORE
LIKE STRATUS POTENTIAL.
SATURDAY - CONFIDENCE...MEDIUM HIGH PRESSURE SETTLES IN. MORNING
FOG/LOW STRATUS POTENTIAL WILL GRADUALLY BURN OFF. NOT A BIG
DROP OFF IN 850 TEMPS. NEVERTHELESS CU RULE SUPPORTIVE OF SCT
COVERAGE AFTER MORNING STRATUS. 925 TEMPS PROGGD TO 20-23C.
COMFORTABLY COOLER AND LESS HUMID. SO LOW TO MID 80S WITH
MID/UPPER 70S IN THE FAR EAST WITH THE SUSTAINED ONSHORE FLOW.
.SHORT TERM...SATURDAY NIGHT THROUGH MONDAY.
SATURDAY NIGHT AND SUNDAY...FORECAST CONFIDENCE MEDIUM TO HIGH.
NEXT BEST CHANCE OF PRECIPITATION COMES WITH SHORT WAVE TROUGH AND
COLD FRONT. STILL SOME DIFFERENCES IN CONFIGURATION OF SHORT WAVE
THAT IMPACTS TIMING OF SURFACE TROUGH/COLD FRONT THROUGH REGION.
WILL GO WITH BLENDED SOLUTION THAT BRINGS A CHANCE TO THE NW CWA
BETWEEN 06Z AND 12Z SUNDAY...THEN HIGH CHANCE POPS ACROSS THE
ENTIRE FORECAST AREA DURING THE DAY SUNDAY. SHOULD SEE LOW TO MID
80S HIGHS PRIOR TO ONSET OF PCPN.
SUNDAY NIGHT AND MONDAY...FORECAST CONFIDENCE HIGH.
PRECIPITATION CHANCES LINGER INTO SUNDAY EVENING IN THE EAST WITH
HIGH PRESSURE BUILDING IN BEHIND. LABOR DAY MORE FALL-LIKE WITH
LOW TO MID 70 HIGHS.
.LONG TERM...MONDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE
MEDIUM TO HIGH.
DRY WEATHER AS HIGH PRESSURE DOMINATES THE WESTERN GREAT LAKES REGION
UNDER NORTHWEST FLOW REGIME. MODELS TRY TO BRUSH SW/SOUTHERN CWA
WITH LIGHT QPF WITH A WEAK WAVE/WARM AIR ADVECTION BUT FOR NOW
WILL LEAVE DRY. BELOW NORMAL TEMPERATURES WILL WARM BACK TOWARD
NORMAL LEVELS...OR SLIGHTLY ABOVE...WEDNESDAY THROUGH THE REST OF
THE EXTENDED.
&&
.AVIATION/00Z TAFS/...
THUNDERSTORM POTENTIAL THROUGH 00Z WITH FRONTAL BOUNDARY DROPPING
IN FROM THE NORTH. WINDS WILL SHIFT TO THE NORTH IN THE WAKE OF
THE FRONT WITH THE EVENING FROPA. WILL MONITOR STRATUS TRENDS IN
THE COOL ADVECTION REGIME. EXPECT MVFR CEILINGS AND POTENTIAL FOR
IFR LATER TONIGHT INTO EARLY SATURDAY. THINKING ENOUGH MIXING WILL
INHIBIT DENSE FOG FORMATION.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL 6 PM CDT THIS EVENING FOR WIZ067>072.
LM...NONE.
&&
$$
TONIGHT/SATURDAY AND AVIATION/MARINE...COLLAR
SATURDAY NIGHT THROUGH FRIDAY...REM
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1030 AM MDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 1022 AM MDT FRI AUG 30 2013
STILL SEEING LOW TO MID 60 DEWPOINTS IN THE PANHANDLE THIS
AFTERNOON. LATEST HRRR RADAR COMPOSITE FORECAST SHOWING SHOWERS
DEVELOPING OVER THE LARAMIE RANGE AROUND 20Z AND THEN DRIFTING OFF
AND MOVING EAST INTO THE PANHANDLE AROUND THE 22Z TO 02Z
TIME FRAME. WENT AHEAD AND INCREASED POPS IN THE PANHANDLE TO
CHANCE/SCATTERED CATEGORY FOR THIS TIME FRAME. THOUGH PWATS ARE NOT
FORECAST TO BE TOO HIGH...GENERALLY AROUND .8 INCHES...FORECAST
STORM MOTIONS ARE FAIRLY SLOW...GENERALLY UNDER 6KTS...SO WE COULD
SEE SOME ISOLATED HEAVY RAIN SHOWERS OUT THAT WAY. ALSO A FEW
STRONG TO SEVERE THUNDERSTORMS ARE NOT TOTALLY OUT OF THE QUESTION
WITH AFTERNOON CAPE VALUES AROUND 1500 TO 200 J/KG. UPDATES HAVE
BEEN SENT.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 335 AM MDT FRI AUG 30 2013
ANOTHER HOT DAY TO END THE WORK WEEK WITH HIGH TEMPERATURES MAINLY
IN THE 90S ACROSS THE PLAINS AND AROUND 100 DEGREES FOR SOME
LOCATIONS. HIGHER ELEVATIONS WILL GENERALLY SEE HIGH TEMPERATURES
IN THE 80S. THE UPPER LEVEL RIDGE WHICH IS RESPONSIBLE FOR THE
ABOVE NORMAL TEMPERATURES WILL TEMPORARILY BREAK DOWN THIS
WEEKEND...PROVIDING A LITTLE RELIEF TO THE HOT WEATHER BUT THE
RIDGE WILL REBUILD EARLY NEXT WEEK WITH DAYTIME TEMPERATURES WELL
ABOVE NORMAL WITH SOME RECORD HIGHS A GOOD POSSIBILITY.
A SUBTLE SHORTWAVE CURRENTLY MOVING ACROSS NIOBRARA COUNTY AND FAR
SOUTHWEST SOUTH DAKOTA HAS PRODUCED A FEW SHOWERS AND EVEN SOME
LIGHTING STRIKES EARLY THIS MORNING. CHANCES FOR SHOWERS AND
THUNDERSTORMS WILL MAINLY PUSH EAST OF THE AREA AFTER SUNRISE AS
THE WAVE EXITS THE FORECAST AREA. MODELS DO SHOW AND WEAK MID
LEVEL FRONT HANGING OVER THE NEBRASKA PANHANDLE AT 12Z BUT FORCING
WEAK ENOUGH THAT NOT EXPECTING MUCH MORE THAN SOME ACCAS
CLOUDS...MAYBE A FEW SPRINKLES. MAIN CHANCE FOR PRECIPITATION WILL
HOLD OFF UNTIL THIS AFTERNOON AS CONVECTIVE TEMPERATURES ARE
REACHED. SHOULD SEE CONVECTION INITIATE FIRST OVER THE MOUNTAINS
THEN MOVING OFF THE MOUNTAINS BY MID AFTERNOON. MAY ALSO SEE
STORMS FIRE OFF OVER THE NEBRASKA PANHANDLE MID AFTERNOON.
SEVERE THUNDERSTORM POTENTIAL IS LOW BUT NOT COMPLETELY OUT OF THE
QUESTION INTO THE NEBRASKA PANHANDLE. 0-6 KM SHEAR MAY PUSH 40 KTS
OVER NORTHERN PORTIONS OF THE FORECAST AREA WITH SURFACE BASED
CAPE 1000-1500 J/KG INTO THE NEBRASKA PANHANDLE. IF THUNDERSTORMS
DEVELOP OVER THE PANHANDLE...ONE OR TWO MARGINALLY SEVERE
THUNDERSTORMS POSSIBLE. GUSTY WINDS WILL BE THE MAIN CONCERN
FARTHER WEST WHERE THE TYPICAL INVERTED-V SOUNDING WILL ONCE AGAIN
BE IN PLACE.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 335 AM MDT FRI AUG 30 2013
QUITE WARM CONDITIONS EXPECTED ACROSS THE CWA DURING THE PERIOD AS
AN UPPER HIGH DRIFTS OVER THE SOUTHERN AND CENTRAL ROCKIES EARLY
IN THE WEEK THEN SHIFTS EAST OVER THE PLAINS THURSDAY. ISOLATED
MAINLY MTN CONVECTION POSSIBLE EARLY IN THE WEEK WHERE BEST
INSTABILITY SHOULD BE REALIZED THEN AS THE WEEK PROGRESSES SOME
SUBTROPICAL MOISTURE SHOULD SPREAD OVER AT LEAST SE WYOMING
ALLOWING FOR AN UPTICK IN CONVECTION THERE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 515 PM MDT THU AUG 29 2013
VFR CONDITIONS EXPECTED OVERALL THROUGH THE TAF PERIOD. ISOLATED
SHOWERS AND A FEW STORMS WILL MOVE ACROSS THE AREA THIS AFTERNOON
INTO THIS EVENING. BRIEF GUSTY WINDS AND MVFR VSBYS POSSIBLE WITH
ANY STORMS.
&&
.FIRE WEATHER...
ISSUED AT 335 AM MDT FRI AUG 30 2013
FIRE WEATHER CONCERNS ARE MINIMAL AS WINDS WILL REMAIN ON THE
LIGHT SIDE THE NEXT SEVERAL DAYS. THE HOT AND DRY CONDITIONS DOES
MAKE THE POTENTIAL FOR FIRE STARTS A GREATER RISK...SUCH THAT
LIGHTNING WITH THUNDERSTORMS DOES POSE SOME FIRE START THREAT THE
NEXT FEW AFTERNOONS. NOT EXPECTING WIDESPREAD DRY LIGHTNING BUT A
FEW DRY STRIKES ARE POSSIBLE MAINLY INTO SOUTHEAST WYOMING WEST OF
THE LARAMIE RANGE.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...CLAYCOMB
SHORT TERM...LIEBL
LONG TERM...RE
AVIATION...RE
FIRE WEATHER...LIEBL