Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/22/13
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
315 PM MST TUE AUG 20 2013
.UPDATE...TO AVIATION DISCUSSION...
&&
.SYNOPSIS...
STRONG HIGH PRESSURE ALOFT WILL KEEP TEMPERATURES WELL ABOVE NORMAL
ACROSS THE REGION THROUGH WEDNESDAY. TEMPERATURES WILL THEN SLOWLY
FALL FROM THURSDAY ONWARD INTO THE UPCOMING WEEKEND AS THE HIGH
PRESSURE WEAKENS. THUNDERSTORM ACTIVITY WILL BE MAINLY CONFINED TO
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX THROUGH FRIDAY...THEN
INCREASE DRAMATICALLY FROM SATURDAY ONWARD INTO EARLY NEXT WEEK AS
DEEP SOUTHERLY FLOW ALOFT DEVELOPS OVER THE REGION...WHICH WILL THEN
BEGIN TO IMPORT DEEP MOISTURE NORTHWARD INTO THE DESERT SOUTHWEST.
&&
.DISCUSSION...
LATEST RAP SHOWS AN ELONGATED RIDGE STRETCHING FROM SOUTHERN AZ
TOWARDS THE FOUR CORNERS WITH EMBEDDED ANTICYCLONIC VORTICITY ACROSS
SOUTH-CENTRAL AZ. MEANWHILE...SURFACE DEWPOINTS CONTINUE TO MIX OUT
AND HAVE DROPPED INTO THE LOWER 50S IN THE PHOENIX AREA AND INTO THE
UPPER 40S AT YUMA. CONVECTION HAS INITIATED THIS AFTERNOON ACROSS
SOUTHERN GILA COUNTY...BUT HAS MAINLY BEEN DRIVEN BY OROGRAPHIC
CONVERGENCE...PARTICULARLY NEAR PINAL PEAK AND THE SKY ISLANDS OF SE
AZ INCLUDING MOUNT LEMMON. HIGHEST COVERAGE OF STORMS IS EXPECTED IN
THESE AREAS LATE THIS AFTERNOON AND THIS EVENING...HOWEVER WEAK
STEERING FLOW ASSOCIATED WITH THE ANTICYCLONE WILL MAKE IT
UNFAVORABLE FOR CELLS TO REACH THE LOWER DESERTS. POPS REMAIN LESS
THAN 10 PERCENT FOR THE PHOENIX AREA.
THIS WEEKEND...LATEST GFS/ECMWF CONTINUE TO INDICATE THAT DEEPER
MOISTURE WILL BE ADVECTED INTO THE DESERT SOUTHWEST AND POPS WERE
INCREASED THIS MORNING FOR THE SATURDAY-MONDAY PERIOD. ADDITIONAL
ADJUSTMENTS WERE MADE THIS AFTERNOON TO LOWER HIGH
TEMPERATURES...DUE TO THE EXPECTED CLOUDINESS AND SCATTERED
PRECIPITATION.
&&
.PREVIOUS DISCUSSION...
A VERY SLOW INCREASE IN CONVECTIVE ACTIVITY IS LIKELY FROM WEDNESDAY
ONWARD INTO FRIDAY AS LEFTOVER MOISTURE FROM THUNDERSTORMS OVER
MEXICO IS PUSHED NORTHWARD INTO THE REGION. THE MAIN CONCERN OVER
THE NEXT COUPLE OF DAYS IS THE VERY HOT TEMPERATURES. CURRENT MODEL
DATA IS FORECASTING AFTERNOON 850MB TEMPERATURES IN THE 28-30C RANGE
BOTH TODAY AND ON WEDNESDAY. THESE TEMPERATURES SUPPORT HIGHS IN THE
LOWER DESERTS IN THE 110-114F RANGE EACH DAY...WITH EXCESSIVE HEAT
CRITERIA BEING MET ACROSS THE LOWER DESERTS. TEMPERATURES SHOULD
COOL A BIT ON THURSDAY AND FRIDAY AS THE RIDGE WEAKENS...WITH 500MB
HEIGHTS FALLING FROM THE 590-592DM RANGE ON WEDNESDAY TO THE
586-588DM RANGE BY FRIDAY.
A DRAMATIC UPTICK IN THE MONSOON ACTIVITY NOW APPEARS QUITE LIKELY
FROM SATURDAY ONWARD INTO EARLY NEXT WEEK AS THE MAIN LONG-WAVE
UPPER RIDGE AXIS SHIFTS OFF TO THE EAST OVER THE CENTRAL PLAINS AND
A LONG-WAVE TROF DIGS SOUTHWARD JUST OFF THE WEST COAST. THIS
PATTERN CHANCE WILL ALLOW DEEP SOUTHERLY FLOW TO DEVELOP ALL THE WAY
FROM THE DEEP TROPICS OFF THE WEST COAST OF MEXICO NORTHWARD INTO
THE SOUTHWEST US. ATMOSPHERIC MOISTURE VALUES ARE EXPECTED TO
SHARPLY INCREASE OVER THE REGION...WITH THE ECMWF SHOWING 1000-700MB
MIXING RATIOS RISING FROM AROUND 8 G/KG ON FRIDAY TO 12-16 G/KG FROM
SUNDAY ONWARD INTO NEXT TUESDAY...WITH PWATS IN THE 1.80-2.00 INCH
RANGE. IN ADDITION...BOTH THE GFS AND ECMWF TAKE A POTENTIAL
TROPICAL CYCLONE NORTHWESTWARD ALONG OR JUST WEST OF THE WEST COAST
OF BAJA CALIFORNIA. THE COMBINATION OF THE DEEP SOUTHERLY FLOW AND
POSSIBLE TROPICAL LOW PRESSURE TO THE WEST WILL LIKELY PRODUCE THE
1ST SIGNIFICANT GULF SURGE THAT WE HAVE SEEN FOR A WHILE...LIKELY
PUSHING SFC DEWPOINTS UP WELL INTO THE 60S...OR EVEN LOWER 70S
ACROSS THE LOWER DESERTS LATE FRIDAY NIGHT OR EARLY SATURDAY...WHICH
WOULD ALLOW WIDESPREAD THUNDERSTORM ACTIVITY TO DEVELOP EACH
DAY...WITH THE POTENTIAL FOR HEAVY RAINFALL FROM THESE
STORMS...ESPECIALLY IF A TROPICAL SYSTEM DOES INDEED TRACK
NORTHWESTWARD ALONG OR NEAR BAJA CALIFORNIA. THE INCREASE IN
CLOUDS...MOISTURE...AND RAINFALL IS EXPECTED TO PUSH HIGH
TEMPERATURES DOWNWARD TO BELOW-NORMAL VALUES...PERHAPS KEEPING HIGHS
BELOW 100F AT SOME LOWER DESERT LOCATIONS ON ONE OR MORE OF THE DAYS.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
STORM ACTIVITY EXPECTED TO STAY OUT OF THE PHX METRO TONIGHT...WITH
ISOLATED DEVELOPMENT WELL TO THE EAST AND SOUTH OF THE AREA. THERE
ARE VERY SLIGHT CHANCES OF OUTFLOW INTRUSIONS LATER IN THE
EVENING...CONFIDENCE TOO LOW TO NOT INCLUDE IN THE 18Z TAFS. BREEZY
WEST WINDS WILL PERSIST THROUGH THE EARLY EVENING BEFORE TYPICAL
EAST DRAINAGE SETS UP IN THE LATE OVERNIGHT. MID TO UPPER LEVEL
DEBRIS CLOUDS MAY LINGER OVERHEAD AOA 12 TO 15KFT AGL.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
QUITE WEATHER DAY FOR THE TERMINALS WITH PATCHES OF FEW TO SCT SKIES
LINGERING THROUGH THE EARLY EVENING. SOUTHERLY WINDS WILL PERSIST AT
KBLH...WITH WEST WINDS DEVELOPING FOR KIPL OVERNIGHT. NO WEATHER
IMPACTS TO AVIATION OPERATIONS EXPECTED FOR THE TAF PERIOD.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
SOUTHERLY FLOW BETWEEN THE MONSOON HIGH IN THE SOUTHERN PLAINS AND A
LOW PRESSURE SYSTEM ALONG THE WEST COAST WILL TRANSPORT DEEPER
MOISTURE INTO THE DESERT SOUTHWEST. LATE WEEK THROUGH THE WEEKEND
WILL SEE ABOVE NORMAL RAIN CHANCES...PARTICULARLY ACROSS
ARIZONA...ALONG WITH AT OR BELOW NORMAL TEMPERATURES. RAINFALL
AMOUNTS MAY EVEN BE ENHANCED BY INCREASING TROPICAL MOISTURE SUNDAY
AND MONDAY...MAINLY EAST OF THE COLORADO RIVER. WINDS WILL BE
RELATIVELY LIGHT THROUGH FRIDAY AND FAVOR NORMAL DIURNAL SPEEDS AND
DIRECTIONS...WITH INCREASING MAINLY SOUTHERLY WIND EXPECTED OVER THE
WESTERN DESERTS THIS WEEKEND WITH GUSTS IN EXCESS OF 25 MPH
POSSIBLE.
$$
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...EXCESSIVE HEAT WARNING UNTIL 8 PM MST WEDNESDAY
AZZ022-023-027-028.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...PERCHA
AVIATION...NOLTE
FIRE WEATHER...CB/HIRSCH
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
130 PM MST TUE AUG 20 2013
.SYNOPSIS...
STRONG HIGH PRESSURE ALOFT WILL KEEP TEMPERATURES WELL ABOVE NORMAL
ACROSS THE REGION THROUGH WEDNESDAY. TEMPERATURES WILL THEN SLOWLY
FALL FROM THURSDAY ONWARD INTO THE UPCOMING WEEKEND AS THE HIGH
PRESSURE WEAKENS. THUNDERSTORM ACTIVITY WILL BE MAINLY CONFINED TO
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX THROUGH FRIDAY...THEN
INCREASE DRAMATICALLY FROM SATURDAY ONWARD INTO EARLY NEXT WEEK AS
DEEP SOUTHERLY FLOW ALOFT DEVELOPS OVER THE REGION...WHICH WILL THEN
BEGIN TO IMPORT DEEP MOISTURE NORTHWARD INTO THE DESERT SOUTHWEST.
&&
.DISCUSSION...
LATEST RAP SHOWS AN ELONGATED RIDGE STRETCHING FROM SOUTHERN AZ
TOWARDS THE FOUR CORNERS WITH EMBEDDED ANTICYCLONIC VORTICITY ACROSS
SOUTH-CENTRAL AZ. MEANWHILE...SURFACE DEWPOINTS CONTINUE TO MIX OUT
AND HAVE DROPPED INTO THE LOWER 50S IN THE PHOENIX AREA AND INTO THE
UPPER 40S AT YUMA. CONVECTION HAS INITIATED THIS AFTERNOON ACROSS
SOUTHERN GILA COUNTY...BUT HAS MAINLY BEEN DRIVEN BY OROGRAPHIC
CONVERGENCE...PARTICULARLY NEAR PINAL PEAK AND THE SKY ISLANDS OF SE AZ
INCLUDING MOUNT LEMMON. HIGHEST COVERAGE OF STORMS IS EXPECTED IN
THESE AREAS LATE THIS AFTERNOON AND THIS EVENING...HOWEVER WEAK
STEERING FLOW ASSOCIATED WITH THE ANTICYCLONE WILL MAKE IT
UNFAVORABLE FOR CELLS TO REACH THE LOWER DESERTS. POPS REMAIN LESS
THAN 10 PERCENT FOR THE PHOENIX AREA.
THIS WEEKEND...LATEST GFS/ECMWF CONTINUE TO INDICATE THAT DEEPER
MOISTURE WILL BE ADVECTED INTO THE DESERT SOUTHWEST AND POPS WERE
INCREASED THIS MORNING FOR THE SATURDAY-MONDAY PERIOD. ADDITIONAL
ADJUSTMENTS WERE MADE THIS AFTERNOON TO LOWER HIGH
TEMPERATURES...DUE TO THE EXPECTED CLOUDINESS AND SCATTERED
PRECIPITATION.
&&
.PREVIOUS DISCUSSION...
A VERY SLOW INCREASE IN CONVECTIVE ACTIVITY IS LIKELY FROM WEDNESDAY
ONWARD INTO FRIDAY AS LEFTOVER MOISTURE FROM THUNDERSTORMS OVER
MEXICO IS PUSHED NORTHWARD INTO THE REGION. THE MAIN CONCERN OVER
THE NEXT COUPLE OF DAYS IS THE VERY HOT TEMPERATURES. CURRENT MODEL
DATA IS FORECASTING AFTERNOON 850MB TEMPERATURES IN THE 28-30C RANGE
BOTH TODAY AND ON WEDNESDAY. THESE TEMPERATURES SUPPORT HIGHS IN THE
LOWER DESERTS IN THE 110-114F RANGE EACH DAY...WITH EXCESSIVE HEAT
CRITERIA BEING MET ACROSS THE LOWER DESERTS. TEMPERATURES SHOULD
COOL A BIT ON THURSDAY AND FRIDAY AS THE RIDGE WEAKENS...WITH 500MB
HEIGHTS FALLING FROM THE 590-592DM RANGE ON WEDNESDAY TO THE
586-588DM RANGE BY FRIDAY.
A DRAMATIC UPTICK IN THE MONSOON ACTIVITY NOW APPEARS QUITE LIKELY
FROM SATURDAY ONWARD INTO EARLY NEXT WEEK AS THE MAIN LONG-WAVE
UPPER RIDGE AXIS SHIFTS OFF TO THE EAST OVER THE CENTRAL PLAINS AND
A LONG-WAVE TROF DIGS SOUTHWARD JUST OFF THE WEST COAST. THIS
PATTERN CHANCE WILL ALLOW DEEP SOUTHERLY FLOW TO DEVELOP ALL THE WAY
FROM THE DEEP TROPICS OFF THE WEST COAST OF MEXICO NORTHWARD INTO
THE SOUTHWEST US. ATMOSPHERIC MOISTURE VALUES ARE EXPECTED TO
SHARPLY INCREASE OVER THE REGION...WITH THE ECMWF SHOWING 1000-700MB
MIXING RATIOS RISING FROM AROUND 8 G/KG ON FRIDAY TO 12-16 G/KG FROM
SUNDAY ONWARD INTO NEXT TUESDAY...WITH PWATS IN THE 1.80-2.00 INCH
RANGE. IN ADDITION...BOTH THE GFS AND ECMWF TAKE A POTENTIAL
TROPICAL CYCLONE NORTHWESTWARD ALONG OR JUST WEST OF THE WEST COAST
OF BAJA CALIFORNIA. THE COMBINATION OF THE DEEP SOUTHERLY FLOW AND
POSSIBLE TROPICAL LOW PRESSURE TO THE WEST WILL LIKELY PRODUCE THE
1ST SIGNIFICANT GULF SURGE THAT WE HAVE SEEN FOR A WHILE...LIKELY
PUSHING SFC DEWPOINTS UP WELL INTO THE 60S...OR EVEN LOWER 70S
ACROSS THE LOWER DESERTS LATE FRIDAY NIGHT OR EARLY SATURDAY...WHICH
WOULD ALLOW WIDESPREAD THUNDERSTORM ACTIVITY TO DEVELOP EACH
DAY...WITH THE POTENTIAL FOR HEAVY RAINFALL FROM THESE
STORMS...ESPECIALLY IF A TROPICAL SYSTEM DOES INDEED TRACK
NORTHWESTWARD ALONG OR NEAR BAJA CALIFORNIA. THE INCREASE IN
CLOUDS...MOISTURE...AND RAINFALL IS EXPECTED TO PUSH HIGH
TEMPERATURES DOWNWARD TO BELOW-NORMAL VALUES...PERHAPS KEEPING HIGHS
BELOW 100F AT SOME LOWER DESERT LOCATIONS ON ONE OR MORE OF THE DAYS.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
EXPECT A BIT OF MID/UPPER LEVEL DEBRIS CLOUDS...BASES AOA 14K
FEET...INTO THE MORNING HOURS WITH SOME HIGH BASED CU DEVELOPING IN
THE AFTERNOON. THREAT FOR THUNDERSTORMS TODAY IS REDUCED...MOST
LIKELY STORMS WILL STAY OUT OF THE DESERTS AND OVER HIGHER
TERRAIN...AS SUCH NO MENTION OF THUNDER WAS MADE IN THE 12Z TAFS.
WINDS WILL AGAIN FAVOR NORMAL DIURNAL SPEEDS AND DIRECTIONS NEXT 24
HOURS.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
NO AVIATION CONCERNS NEXT 24 HOURS...STORM THREATS ARE MINIMAL.
OUTSIDE OF SOME MORNING MID/UPPER LEVEL DEBRIS CLOUD...EXPECT
RELATIVELY SUNNY SKIES TODAY. WIND SHOULD FAVOR THE WEST AT KIPL
TODAY AND THE SOUTH/SOUTHWEST AT KBLH.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
SOUTHERLY FLOW BETWEEN THE MONSOON HIGH IN THE SOUTHERN PLAINS AND A
LOW PRESSURE SYSTEM ALONG THE WEST COAST WILL TRANSPORT DEEPER
MOISTURE INTO THE DESERT SOUTHWEST. LATE WEEK THROUGH THE WEEKEND
WILL SEE ABOVE NORMAL RAIN CHANCES...PARTICULARLY ACROSS
ARIZONA...ALONG WITH AT OR BELOW NORMAL TEMPERATURES. RAINFALL
AMOUNTS MAY EVEN BE ENHANCED BY INCREASING TROPICAL MOISTURE SUNDAY
AND MONDAY...MAINLY EAST OF THE COLORADO RIVER. WINDS WILL BE
RELATIVELY LIGHT THROUGH FRIDAY AND FAVOR NORMAL DIURNAL SPEEDS AND
DIRECTIONS...WITH INCREASING MAINLY SOUTHERLY WIND EXPECTED OVER THE
WESTERN DESERTS THIS WEEKEND WITH GUSTS IN EXCESS OF 25 MPH
POSSIBLE.
$$
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...EXCESSIVE HEAT WARNING UNTIL 8 PM MST WEDNESDAY
AZZ022-023-027-028.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...PERCHA
AVIATION...CB
FIRE WEATHER...CB/HIRSCH
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
905 AM MST TUE AUG 20 2013
.SYNOPSIS...
STRONG HIGH PRESSURE ALOFT WILL KEEP TEMPERATURES WELL ABOVE NORMAL
ACROSS THE REGION THROUGH WEDNESDAY. TEMPERATURES WILL THEN SLOWLY
FALL FROM THURSDAY ONWARD INTO THE UPCOMING WEEKEND AS THE HIGH
PRESSURE WEAKENS. THUNDERSTORM ACTIVITY WILL BE MAINLY CONFINED TO
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX THROUGH FRIDAY...THEN
INCREASE DRAMATICALLY FROM SATURDAY ONWARD INTO EARLY NEXT WEEK AS
DEEP SOUTHERLY FLOW ALOFT DEVELOPS OVER THE REGION...WHICH WILL THEN
BEGIN TO IMPORT DEEP MOISTURE NORTHWARD INTO THE DESERT SOUTHWEST.
&&
.DISCUSSION...
LATEST RAP SHOWS THE CENTER OF THE ANTICYCLONIC CIRCULATION ACROSS
SOUTH-CENTRAL AZ. LATEST BLENDED TPW INDICATES THAT RELATIVELY DRY
AIR HAS WORKED ITS WAY INTO THE SONORAN DESERT. WARM POCKET ALOFT
ASSOCIATED WITH THE HIGH WILL YIELD WEAK LAPSE RATES WHICH WILL
INHIBIT CONVECTION AND POPS WERE LOWERED ACROSS MUCH OF THE AREA.
THIS IS ALSO IN LINE WITH ALL HI-RES CONVECTIVE ALLOWING MODELS.
BIGGER STORY TODAY WILL BE THE CONTINUATION OF THE EXCESSIVE HEAT
WITH HIGH TEMPERATURES AGAIN EXCEEDING 110 DEGREES IN PHOENIX. THE
EXCESSIVE HEAT WARNING REMAINS IN EFFECT THROUGH 8 PM FOR THE
GREATER PHOENIX AREA.
GFS/ECMWF CONTINUE TO INDICATE THAT CONDITIONS WILL MOISTEN UP THIS
WEEKEND...EITHER FROM AN APPROACHING INVERTED TROUGH...A GULF
SURGE...REMNANTS OF A TROPICAL SYSTEM OR A COMBINATION OF THE THREE.
POPS WERE INCREASED FROM SATURDAY INTO EARLY NEXT WEEK AND ARE NOW
AS HIGH AS 50 PERCENT FOR SUNDAY AFTERNOON/EVENING.
&&
.PREVIOUS DISCUSSION...
THUS...NOT EXPECTING MUCH CHANGE IN THE AMOUNT OF CONVECTIVE
ACTIVITY TODAY...WITH VIRTUALLY ALL ACTIVITY TO BE CONFINED TO THE
HIGHER TERRAIN NORTH AND EAST OF PHOENIX...WITH MAYBE SOME OUTFLOWS
MAKING THEIR WAY INTO THE LOWER DESERTS THIS EVENING. A VERY SLOW
INCREASE IN CONVECTIVE ACTIVITY IS LIKELY FROM WEDNESDAY ONWARD INTO
FRIDAY AS LEFTOVER MOISTURE FROM THUNDERSTORMS OVER MEXICO IS PUSHED
NORTHWARD INTO THE REGION. THE MAIN CONCERN OVER THE NEXT COUPLE OF
DAYS IS THE VERY HOT TEMPERATURES. CURRENT MODEL DATA IS FORECASTING
AFTERNOON 850MB TEMPERATURES IN THE 28-30C RANGE BOTH TODAY AND ON
WEDNESDAY. THESE TEMPERATURES SUPPORT HIGHS IN THE LOWER DESERTS IN
THE 110-114F RANGE EACH DAY...WITH EXCESSIVE HEAT CRITERIA BEING MET
ACROSS THE LOWER DESERTS. TEMPERATURES SHOULD COOL A BIT ON THURSDAY
AND FRIDAY AS THE RIDGE WEAKENS...WITH 500MB HEIGHTS FALLING FROM
THE 590-592DM RANGE ON WEDNESDAY TO THE 586-588DM RANGE BY FRIDAY.
A DRAMATIC UPTICK IN THE MONSOON ACTIVITY NOW APPEARS QUITE LIKELY
FROM SATURDAY ONWARD INTO EARLY NEXT WEEK AS THE MAIN LONG-WAVE
UPPER RIDGE AXIS SHIFTS OFF TO THE EAST OVER THE CENTRAL PLAINS AND
A LONG-WAVE TROF DIGS SOUTHWARD JUST OFF THE WEST COAST. THIS
PATTERN CHANCE WILL ALLOW DEEP SOUTHERLY FLOW TO DEVELOP ALL THE WAY
FROM THE DEEP TROPICS OFF THE WEST COAST OF MEXICO NORTHWARD INTO
THE SOUTHWEST US. ATMOSPHERIC MOISTURE VALUES ARE EXPECTED TO
SHARPLY INCREASE OVER THE REGION...WITH THE ECMWF SHOWING 1000-700MB
MIXING RATIOS RISING FROM AROUND 8 G/KG ON FRIDAY TO 12-16 G/KG FROM
SUNDAY ONWARD INTO NEXT TUESDAY...WITH PWATS IN THE 1.80-2.00 INCH
RANGE. IN ADDITION...BOTH THE GFS AND ECMWF TAKE A POTENTIAL
TROPICAL CYCLONE NORTHWESTWARD ALONG OR JUST WEST OF THE WEST COAST
OF BAJA CALIFORNIA. THE COMBINATION OF THE DEEP SOUTHERLY FLOW AND
POSSIBLE TROPICAL LOW PRESSURE TO THE WEST WILL LIKELY PRODUCE THE
1ST SIGNIFICANT GULF SURGE THAT WE HAVE SEEN FOR A WHILE...LIKELY
PUSHING SFC DEWPOINTS UP WELL INTO THE 60S...OR EVEN LOWER 70S
ACROSS THE LOWER DESERTS LATE FRIDAY NIGHT OR EARLY SATURDAY...WHICH
WOULD ALLOW WIDESPREAD THUNDERSTORM ACTIVITY TO DEVELOP EACH
DAY...WITH THE POTENTIAL FOR HEAVY RAINFALL FROM THESE
STORMS...ESPECIALLY IF A TROPICAL SYSTEM DOES INDEED TRACK
NORTHWESTWARD ALONG OR NEAR BAJA CALIFORNIA. THE INCREASE IN
CLOUDS...MOISTURE...AND RAINFALL IS EXPECTED TO PUSH HIGH
TEMPERATURES DOWNWARD TO BELOW-NORMAL VALUES...PERHAPS KEEPING HIGHS
BELOW 100F AT SOME LOWER DESERT LOCATIONS ON ONE OR MORE OF THE DAYS.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
EXPECT A BIT OF MID/UPPER LEVEL DEBRIS CLOUDS...BASES AOA 14K
FEET...INTO THE MORNING HOURS WITH SOME HIGH BASED CU DEVELOPING IN
THE AFTERNOON. THREAT FOR THUNDERSTORMS TODAY IS REDUCED...MOST
LIKELY STORMS WILL STAY OUT OF THE DESERTS AND OVER HIGHER
TERRAIN...AS SUCH NO MENTION OF THUNDER WAS MADE IN THE 12Z TAFS.
WINDS WILL AGAIN FAVOR NORMAL DIURNAL SPEEDS AND DIRECTIONS NEXT 24
HOURS.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
NO AVIATION CONCERNS NEXT 24 HOURS...STORM THREATS ARE MINIMAL.
OUTSIDE OF SOME MORNING MID/UPPER LEVEL DEBRIS CLOUD...EXPECT
RELATIVELY SUNNY SKIES TODAY. WIND SHOULD FAVOR THE WEST AT KIPL
TODAY AND THE SOUTH/SOUTHWEST AT KBLH.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
SOUTHERLY FLOW BETWEEN THE MONSOON HIGH IN THE SOUTHERN PLAINS AND A
LOW PRESSURE SYSTEM ALONG THE WEST COAST WILL TRANSPORT DEEPER
MOISTURE INTO THE DESERT SOUTHWEST. LATE WEEK THROUGH THE WEEKEND
WILL SEE ABOVE NORMAL RAIN CHANCES...PARTICULARLY ACROSS
ARIZONA...ALONG WITH AT OR BELOW NORMAL TEMPERATURES. RAINFALL
AMOUNTS MAY EVEN BE ENHANCED BY INCREASING TROPICAL MOISTURE SUNDAY
AND MONDAY...MAINLY EAST OF THE COLORADO RIVER. WINDS WILL BE
RELATIVELY LIGHT THROUGH FRIDAY AND FAVOR NORMAL DIURNAL SPEEDS AND
DIRECTIONS...WITH INCREASING MAINLY SOUTHERLY WIND EXPECTED OVER THE
WESTERN DESERTS THIS WEEKEND WITH GUSTS IN EXCESS OF 25 MPH
POSSIBLE.
$$
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...EXCESSIVE HEAT WARNING ACROSS THE SOUTH CENTRAL DESERTS...
AZZ022...AZ023...AZZ027...AZZ028...FROM 10 AM TODAY THROUGH 8
PM WEDNESDAY.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...PERCHA
AVIATION...CB
FIRE WEATHER...CB/HIRSCH
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
1112 PM PDT MON AUG 19 2013
...A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH MIDWEEK...
...RED FLAG WARNING FOR DRY THUNDERSTORMS IN EFFECT...
.DISCUSSION...AS OF 8:40 PM PDT MONDAY...AN UPPER LOW OFF THE
CENTRAL CA COASTLINE CONTINUES TO DOMINATE THE WEATHER PATTERN.
ALL AFTERNOON AND EVENING A LINE OF THUNDERSTORMS EXTENDING FROM
NEAR HALF MOON BAY WEST OVER 100 NM OFFSHORE HAS PRODUCED
THOUSANDS OF LIGHTNING STRIKES. OVER THE PAST HOUR...THESE
THUNDERSTORMS CONTINUES TO BUILD EAST OVER LAND...WITH LIGHTNING
REPORTED AS FAR EAST AS LOS GATOS. IN FACT...IN A ONE HOUR
PERIOD...ENDING AT 7:55 PM...2570 LIGHTNING STRIKES WERE REPORTED
FROM THIS LINE OF THUNDERSTORMS.
THESE THUNDERSTORMS ARE FORECAST TO CONTINUE THROUGH THE OVERNIGHT
HOURS...AND ACTUALLY BACK BUILD TO THE SOUTH AND EAST. BOTH THE NAM
AND HRRR INDICATE THAT THESE STORMS WILL CONTINUE THROUGH THE
12Z TIME FRAME BEFORE THE LOW SHIFTS SLIGHTLY TO THE WEST ALLOWING
THE CONVECTION TO SHIFT TO THE WEST. THE MAIN CONCERN WITH ALL OF
THESE LIGHTNING STRIKES ARE THE POSSIBILITY OF FIRE STARTS.
OTHERWISE...CURRENT FORECAST LOOKS RIGHT ON TRACK WITH THE MAIN
FOCUS OF THUNDERSTORMS FROM THE SF BAY SOUTHWARD THOUGH THE
MORNING HOURS ON TUESDAY. PLEASE CONTINUE TO MONITOR THE FORECAST
FOR THE LATEST INFORMATION REGARDING THE THUNDERSTORMS ACROSS THE
AREA.
.PREVIOUS DISCUSSION...AS OF 2:26 PM PDT MONDAY...MID/UPPER LEVEL
LOW POSITIONED ABOUT 200 MILES TO THE SOUTHWEST OF MONTEREY THIS
AFTERNOON. THIS FEATURE CONTINUES TO PULL MID-LEVEL MOISTURE
ACROSS THE REGION AND HAS CONTRIBUTED TO ELEVATED CONVECTION
ACROSS THE COASTAL WATERS. AS THE LOW REMAINS OFF THE CENTRAL
COAST...THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE
FORECAST FOR PORTIONS OF THE REGION. CHANCES INCREASE ACROSS THE
NORTH AND DIMINISH OVER THE SOUTH TONIGHT THROUGH WEDNESDAY AS
500-700MB MOISTURE INCREASES AND THE LOW BEGINS TO LIFT TO THE
NORTH-NORTHEAST AND APPROACH THE SAN FRANCISCO BAY REGION.
WITH RESPECT TO TEMPERATURES...AFTERNOON TEMPERATURES WILL BE
SLIGHTLY BELOW SEASONAL AVERAGE THROUGH MIDWEEK AS THE AIR MASS
ASSOCIATED WITH THE UPPER LOW APPROACHES THE REGION. WARMEST
CONDITIONS WILL BE INLAND WITH COOLER TEMPERATURES ALONG THE COAST
WITH PERSISTENT ONSHORE FLOW. INLAND TEMPERATURES MAY BE SLOWER TO
WARM OVER THE NORTH WHERE HIGH CLOUDINESS IS MORE LIKELY.
THE INCREASED MOISTURE WILL KEEP OVERNIGHT TEMPERATURES FROM
FALLING MUCH...AND WILL ALSO ALLOW FOR PATCHY FOG DEVELOPMENT
THROUGH MIDWEEK.
BY THURSDAY THE UPPER LOW QUICKLY GETS PICKED UP BY THE MEAN FLOW
AND PULLS WELL NORTH OF THE REGION. THIS PATTERN WILL BE REPLACED
BY MID/UPPER LEVEL TROUGH OFF THE WEST COAST AND WILL MAINTAIN
BELOW NORMAL TEMPERATURES AND A DRY FORECAST LATE THIS WEEK THROUGH
EARLY NEXT WEEK.
&&
.AVIATION...AS OF 11:00 PM PDT MONDAY...QUITE A BUSY EVE. LINE OF
ELEVATED CONVECTION HAS BEEN TIED CLOSELY TO WHERE RECENT MODEL
FORECASTS HAVE SHOWN TOTAL TOTALS INDEX TO BE AT A MAXIMUM. THE
UPPER LOW OFF THE CENTRAL COAST IS FORECAST TO REMAIN NEARLY
STATIONARY OVERNIGHT. BEST CHANCES FOR ADDITIONAL CONVECTION WILL
REMAIN OVER THE SOUTHERN HALF OF THE FORECAST AREA TONIGHT.
VICINITY OF KSFO...STRATUS COULD HOLD OFF FOR MUCH OF THE NIGHT.
MODERATE CONFIDENCE.
KSFO BRIDGE APPROACH...VFR.
MONTEREY BAY AREA TERMINALS...IFR TONIGHT. CLEARING IS EXPECTED BY
LATE TUESDAY MORNING.
&&
.FIRE WEATHER...AS OF 11:10 AM PDT MONDAY...A STATIONARY UPPER
LEVEL LOW OFF THE SOUTH-CENTRAL CALIFORNIA COAST CONTINUES TO DRAW
MONSOONAL MOISTURE NORTH AND WEST ACROSS CALIFORNIA. THUNDERSTORMS
HAVE THUS FAR BEEN CONFINED TO AREAS WELL TO THE EAST OF THE
DISTRICT...BUT THE MODELS CONTINUE TO FORECAST INCREASING MID
LEVEL MOISTURE AND INSTABILITY ACROSS THE REGION TODAY.
THUS...THUNDERSTORM CHANCES REMAIN IN THE FORECAST.
INITIALLY...ISOLATED THUNDERSTORMS WILL PRODUCE LITTLE...IF
ANY...RAINFALL. WILL CONTINUE WITH A RED FLAG WARNING FOR MOST
INLAND PORTIONS OF THE DISTRICT. THE MODELS HAVE BACKED OFF
SLIGHTLY ON THE AMOUNT OF MOISTURE AND INSTABILITY ACROSS OUR
REGION OVER THE NEXT FEW DAYS...BUT NOT ENOUGH TO WARRANT A
CANCELING OF THE WARNING.
THE LOW WILL BEGIN TO LIFT TO THE NORTH ON TUESDAY AND
THUNDERSTORM CHANCES WILL END FROM SOUTH TO NORTH BEGINNING ON
TUESDAY MORNING. WILL THEREFORE MAINTAIN A RED FLAG WARNING FOR
MONTEREY AND SAN BENITO COUNTIES ONLY THROUGH MIDDAY TUESDAY...BUT
CONTINUE THE WARNING THROUGH AT LEAST TUESDAY NIGHT FOR THE SF BAY
AREA. THUNDERSTORMS WILL LIKELY PRODUCE DECENT RAINFALL BY LATE
MONDAY...BUT EVEN THEN NEW FIRE STARTS WILL STILL BE POSSIBLE
GIVEN HOW DRY THE FUELS ARE.
&&
.FIRE WEATHER...
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TNGT...RED FLAG WARNING...MOST INLAND PORTIONS OF THE SAN
FRANCISCO AND MONTEREY BAY AREAS.
&&
$$
PUBLIC FORECAST: RILEY/RGASS
AVIATION/MARINE: CANEPA
FIRE WEATHER: RILEY
VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO
FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
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AREA FORECAST DISCUSSION
NWS SAN JOAQUIN VALLEY - HANFORD CA
1102 PM PDT MON AUG 19 2013
.UPDATE...RAISED POPS AND SKY COVER THRU TUESDAY EVENING OVER THE
MOUNTAINS AND DESERT.
&&
.SYNOPSIS...
A LOW PRESSURE CENTER OFF THE CENTRAL COAST WILL BRING A CHANCE OF
MAINLY AFTERNOON AND EVENING THUNDERSTORMS OVER THE SIERRA NEVADA
THROUGH WEDNESDAY. THERE WILL ALSO BE A SLIGHT CHANCE OF
THUNDERSHOWERS FOR THE SAN JOAQUIN VALLEY THROUGH EARLY TUESDAY
MORNING. THE LOW WILL LIFT NORTHEAST OUT OF THE REGION BY THURSDAY
AND BRING A RETURN OF DRIER WEATHER FOR THE END OF THE WEEK.
&&
.DISCUSSION...AFTER A VERY ACTIVE EVENING LATEST RADAR IMAGERY
SHOWS SHOWERS AND ISOLATED THUNDERSTORMS DIMINISHING FROM FRESNO
COUNTY AND NORTHWARD OVER THE SAN JOAQUIN VALLEY AND SIERRA
NEVADA. ANOTHER ROUND OF SHOWERS AND ISOLATED THUNDERSTORMS IS
POSSIBLE OVER THE MOUNTAINS...SIERRA FOOTHILLS AND DESERT BY TUE
AFTERNOON. CUTOFF LOW REMAINS CENTERED OFF THE COAST OF PT
CONCEPTION AND IS EXPECTED TO MOVE NORTHEASTWARD TOWARD THE SF BAY
AREA BY WEDNESDAY EVENING. HAVE INCREASED POPS FOR TUE AND TUE
EVENING AS CUTOFF LOW WILL REMAIN STATIONARY OFF THE CENTRAL CA
COAST.
&&
.PREVIOUS DISCUSSION...
UPPER LOW OFF THE COAST IN CONJUNCTION WITH LARGE SCALE UPPER
RIDGE OVER THE FOUR CORNERS IS PROVIDING A SQUEEZE PLAY TO STREAM
MID LEVEL SUB TROPICAL MOISTURE INTO THE CENTRAL CA INTERIOR.
T-STORMS ARE ONCE AGAIN FIRING UP OVER THE SIERRA AND ALONG THE
TEHACHAPI RANGE ATTM. UPSLOPE CONDITIONS IN ASSOCIATION WITH
MODERATE MUCAPES FROM THE VEGAS SOUNDING OF OVER 2000 J/KG ARE
PROVIDING ENOUGH LIFT TO GET IT GOING AGAIN TODAY. BLENDED PWAT
VALUES OF 1.0-1.5 ARE OVER THE REGION WILL PROVIDE ENOUGH MOISTURE
TO SUPPORT THUNDERSTORMS. ACTIVE PATTERN WILL CONTINUE INTO THE
OVERNIGHT HOURS AS UPPER LOW REMAINS STATIONARY OFF THE COAST AND
MOISTURE FEED CONTINUES.
19Z RUN OF THE HRRR IS PAINTING MOST OF THE CWA WITH QPF FOR THIS
EVENING. EVEN SPREADS QPF INTO THE VALLEY AND OVER TO THE WEST
SIDE OF THE SJV. SOME FLASH FLOODING IS POSSIBLE WITH THE STORMS
IN THE MOUNTAINS AS MOVEMENT IS ONLY AROUND 10 MPH. ADDITIONAL
FIRE STARTS ARE ALSO POSSIBLE WITH NUMEROUS LIGHTNING STROKES
ASSOCIATED THE STORMS.
THE UPPER LOW BEGINS TO OPEN UP AND LIFT NE. BOTH THE MEAN
ENSEMBLE GFS AND THE 12Z OPERATIONAL ECM ARE IN DECENT AGREEMENT
WITH LIFTING THE FEATURE NE BY WED AND SW FLOW ALOFT SETTING UP
WITH DRIER CONDITIONS. EPAC TROUGH WILL DIG SOUTH AND FEED ANOTHER
ROUND OF SUB TROPICAL MOISTURE INTO THE REGION. HAVE INTRODUCED
POPS FOR SUNDAY AND MONDAY OVER THE SIERRA AND OVER THE
TEHACHAPIS.
&&
.AVIATION...
SCATTERED SHOWERS AND THUNDERSTORMS WITH LOCAL MVFR/IFR CONDITIONS
EXPECTED TO REDEVELOP OVER THE MOUNTAINS AND MOJAVE DESERT AFTER 18Z
TUESDAY. OTHERWISE...MAINLY VFR CONDITIONS WILL PREVAIL THROUGHOUT
THE CENTRAL CALIFORNIA INTERIOR DURING THE NEXT 24 HOURS.
&&
.AIR QUALITY ISSUES...
NONE.
&&
.CERTAINTY...
THE LEVEL OF CERTAINTY FOR DAYS 1 AND 2 IS MEDIUM.
THE LEVEL OF CERTAINTY FOR DAYS 3 THROUGH 7 IS HIGH.
THIS INFORMATION IS PROVIDED AS PART OF A TRIAL PROJECT CONDUCTED
BY THE NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD.
CERTAINTY LEVELS INCLUDE LOW...MEDIUM...AND HIGH. PLEASE VISIT
WWW.WEATHER.GOV/HNX/CERTAINTY.PHP /ALL LOWER CASE/ FOR ADDITIONAL
INFORMATION AND/OR TO PROVIDE FEEDBACK.
&&
.CLIMATE...
RECORDS
SITE DATE HI_MAX:YEAR LO_MAX:YEAR HI_MIN:YEAR LO_MIN:YEAR
KFAT 08-19 108:1892 67:1976 74:2012 54:1916
KFAT 08-20 108:1919 76:1959 75:1986 54:1974
KFAT 08-21 108:1919 80:1968 76:1913 51:1959
KBFL 08-19 109:1950 78:1959 79:1961 52:1913
KBFL 08-20 112:1950 77:1959 79:1950 52:1912
KBFL 08-21 110:1919 80:1968 77:1982 51:1918
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 11 PM PDT THIS EVENING CAZ094-097.
&&
$$
PUBLIC...BSO
AVN/FW...JEB
SYNOPSIS...ANDERSEN
WEATHER.GOV/HANFORD
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1013 PM CDT WED AUG 21 2013
.DISCUSSION...
304 PM CDT
THE MAIN FORECAST CONCERN IN THE SHORT TERM WILL BE TIMING THE BEST
CHANCES FOR SCT SHOWER AND THUNDER ACTIVITY TONIGHT INTO THURSDAY.
THEREAFTER...TEMPERATURES WILL BE THE PRIMARY CONCERN...WITH A GOOD
POTENTIAL FOR ANOTHER SEVERAL DAY PERIOD OF WELL ABOVE NORMAL
WEATHER LATER THIS WEEKEND INTO NEXT WEEK.
A POTENT AREA OF LOW PRESSURE ACROSS THE HUDSON BAY AND NORTHERN
QUEBEC...IS BEING FUELED BY A ENHANCED BELT OF 110+ KT UPPER LEVEL
WESTERLIES ENCOMPASSING MUCH OF SOUTHERN CANADA. AT THE SURFACE...AN
ASSOCIATED COLD FRONTAL BOUNDARY IS NOW DROPPING SOUTHWARD ACROSS
THE UPPER MIDWEST AND NORTHERN PLAINS. THIS FRONTAL BOUNDARY IS
EXPECTED TO BE THE MAIN DRIVER FOR OUR BEST CHANCES OF CONVECTION
FOR AT LEAST THE NEXT 7 DAYS.
THUNDERSTORMS WILL LIKELY CONTINUE TO FIRE UP THROUGH THE AFTERNOON
TO OUR NORTH ACROSS NORTHERN WISCONSIN AND POINTS SOUTHWESTWARD AS
THIS COLD FRONT INTERACTS WITH AN UNSTABLE WARM SECTOR AIR MASS. A
SEVERE WEATHER THREAT IS HIGHLIGHTED BY THE SPC ACROSS THIS REGION.
HOWEVER...THE SEVERE THREAT WILL DIMINISH THROUGH THE EVENING AS THE
COLD FRONT MOVES TOWARDS NORTHERN ILLINOIS.
ALTHOUGH MUCH OF THE MID AND UPPER-LEVEL SUPPORT IS EXPECTED TO
REMAIN WELL NORTH OF THE AREA...ASSOCIATED WITH THE STRONGER BELT OF
UPPER LEVEL FLOW....WATER VAPOR IMAGERY DOES INDICATE THE PRESENCE
OF SOME PERTURBED MID-LEVEL FLOW...WITH A SERIES OF MID-LEVEL
DISTURBANCES ROTATING ALONG THE WESTERN AND NORTHERN PERIPHERY OF A
MID/UPPER-LEVEL ANTICYCLONE ACROSS THE CENTRAL AND SOUTHERN PLAINS.
IT APPEARS THAT SOME OF THESE DISTURBANCES MAY COMPLEMENT SOME OF
THE MODEST FRONTAL SCALE FORCING/MOISTURE CONVERGENCE ALONG AND NEAR
THE FRONTAL BOUNDARY TONIGHT TO HELP KEEP AT LEAST SOME WIDELY
SCATTERED TO SCATTERED STORMS GOING ACROSS THE AREA TONIGHT.
ALTHOUGH THE THREAT FOR SEVERE STORMS WILL BE VERY LOW...THERE COULD
BE A FEW GUSTY WINDS WITH SOME OF THE STRONGER STORMS. IT ALSO
APPEARS THAT THESE STORMS WILL BE CAPABLE OF PRODUCING BRIEF
TORRENTIAL DOWNPOURS OVERNIGHT. GUIDANCE CONTINUES TO INDICATE
PRECIPITABLE WATER VALUES TOPPING OUT AT OR ABOVE 1.65
INCHES...WHICH SHOULD ALLOW FOR GO EFFICIENT RAINFALL IN THE
STRONGEST SHOWERS. WITH THIS IN MIND I DID UP QPF AMOUNTS
TONIGHT...ESPECIALLY ACROSS NORTHEASTERN ILLINOIS.
IT APPEARS THAT SHOWERS AND THUNDERSTORMS MAY REGENERATE/CONTINUE
ACROSS THE AREA THURSDAY MORNING...AS ADDITIONAL DISTURBANCES MOVE
TOWARDS THE AREA AND INTERACT WITH THE SURFACE BOUNDARY. THESE
STORMS COULD AGAIN POSS AN ISOLATED HEAVY RAIN THREAT.
OTHERWISE...THE SURFACE FRONT SHOULD TOWARDS MY SOUTHERN COUNTIES
DURING THE AFTERNOON...PLACING THE MAIN THREAT FOR CONVECTION ACROSS
MY SOUTHERN COUNTIES LATER THURSDAY. IN SPITE OF THIS...GUIDANCE HAS
BEEN INSISTENT IN SOME ADDITIONAL ISOLATED TO SCATTERED CONVECTION
DEVELOPING ACROSS NORTHEASTERN ILLINOIS DURING AT LEAST THE EARLY
AFTERNOON...LIKELY IN ASSOCIATION WITH A DECENT BOUNDARY LAYER
CONVERGENCE ALONG A LAKE BREEZE BOUNDARY. WITH THIS IN MIND...IT DID
KEEP SOME SLIGHT CHANCE POPS GOING INTO THE EARLY AFTERNOON ACROSS
FAR NORTHERN ILLINOIS. OTHERWISE...THE CONVECTIVE THREAT SHOULD COME
TO AN END AREA-WIDE BY EARLY THURSDAY EVENING. THIS LOOKS TO BE THE
ONLY DECENT CHANCE FOR PRECIP DURING THE REST OF THE FORECAST
PERIOD.
SURFACE HIGH PRESSURE BUILDS ACROSS THE GREAT LAKES FOR FRIDAY. THIS
SHOULD RESULT IN ONSHORE FLOW FRIDAY...WITH COOLER TEMPERATURES
INTO SATURDAY.
THIS COOL DOWN WILL BE VERY SHORT LIVED...HOWEVER...AS THE SURFACE
HIGH QUICKLY SHIFTS EASTWARD. ONCE THIS OCCURS...A VERY WARM AIR MASS
IS EXPECTED TO DEVELOP ACROSS THE PLAINS AND THEN SHIFT EASTWARD
ACROSS THE AREA LATER THIS WEEKEND AND INTO...AT LEAST...THE MIDDLE
OF NEXT WEEK. THE MODEL GUIDANCE IS FORECASTING A CLASSIC
MID/UPPER-LEVEL DOME OF OF HIGH PRESSURE...WHICH LOOKS TO ENCOMPASS
MUCH OF THE CENTRAL CONUS. THIS SHOULD RESULT IN A DRY WEATHER
PATTERN AS THE MAIN STORM TRACK/RIDGE RUNNERS REMAINING WELL NORTH
OF THE AREA. THE MAIN STORY WITH THIS WEATHER PATTERN WILL BE THE
VERY WARM TEMPERATURES...ESPECIALLY SUNDAY THROUGH AT LEAST TUESDAY.
GUIDANCE CONTINUES IN GOOD AGREEMENT WITH PROGGED 850 AND 925 MB
TEMPERATURES OF 20-22 AND 26-28 DEGREES CELSIUS...RESPECTIVELY. THIS
COULD SUPPORT TEMPERATURES WELL INTO THE 90S...POSSIBLY AS HIGH AS
MID TO UPPER 90S...ESPECIALLY MONDAY AND TUESDAY. WITH THIS IN
MIND...I WARMED TEMPERATURES OVER GUIDANCE...INDICATING LOW TO MID
90S. RECORD HIGHS FOR MONDAY AND TUESDAY ARE 97 DEGREES AT BOTH
CHICAGO AND ROCKFORD.
UNCERTAINTY INCREASES BY WEDNESDAY...WITH THE MODELS A BIT UNCERTAIN
ON IF A COOL FRONT MAKES IT ACROSS NORTHERN ILLINOIS. THEREFORE...IT
DID NOT MAKE ANY SIGNIFICANT CHANGES FOR WEDNESDAY.
HOWEVER...TEMPERATURES COULD AGAIN JUMP ABOVE 90
DEGREES...DEPENDING ON THE TIMING AND ACTUAL EXISTENCE OF THIS
COLD FRONT.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* SHRA/TSRA POTENTIAL LATE TONIGHT/EARLY THURSDAY.
* WIND TRENDS LATE TONIGHT THROUGH THURSDAY MORNING WITH SHRA/TSRA
COMPLEX AND THEN COLD FRONT PASSAGE.
* CHANCE OF MVFR CIGS THURSDAY MORNING FOR A SHORT PERIOD BEHIND
COLD FRONT.
RC
//DISCUSSION...UPDATED 00Z...
UNCERTAIN AND LOW CONFIDENCE CONVECTIVE FORECAST LATE TONIGHT INTO
EARLY THURSDAY...WITH SHRA/TSRA POTENTIAL STILL EXPECTED TO BE
TIED IN SOME FASHION TO TSRA COMPLEX OVER WISCONSIN AND POSSIBLY
ACTIVITY OVER IOWA AND SOUTHERN MN AS WELL. INSTABILITY WILL BE ON
THE DOWNSWING BY THE TIME ANY TSRA APPROACH THE TERMINALS...SO A
WEAKENING TREND WOULD BE EXPECTED. NONETHELESS HAVE MAINTAINED
TIMING FROM 22Z UPDATE. IF TSRA DIRECTLY AFFECT THE
TERMINALS...MVFR OR LOWER VSBY IS POSSIBLE. ALL OF THE ACTIVITY
IS WELL AHEAD OF A COLD FRONT THAT WILL BE APPROACHING THURSDAY
MORNING. WINDS BEHIND ANY TSRA SHOULD TURN WEST TO
NORTHWEST...BUT MAY EVEN TREND BACK SOUTHWEST FOR A TIME PRIOR TO
THE COLD FRONT.
DO NOT ANTICIPATE ANY MORE SHRA/TSRA WITH FRONT DUE TO
PREFRONTAL CONVECTION...SO MAIN IMPACT WILL BE WIND SHIFT TO
NORTH-NORTHWEST AND THEN QUICKLY FLIPPING OVER TO NORTHEAST WITH A
HYBRID LAKE BREEZE. GUIDANCE INDICATES HIGH MOISTURE AT OR BELOW
2000 FT AGL FOR A FEW HOURS AFTER THE FRONTAL PASSAGE BEFORE
CLEARING...SO THERE COULD BE A PERIOD OF LOW-MID MVFR CIGS BUT DO
NOT HAVE HIGH CONFIDENCE IN THIS OCCURRING. ITS NOT OUT OF THE
QUESTION FOR THERE TO BE A FEW SHRA/TSRA POPPING UP ON THE LAKE
BREEZE...BUT COVERAGE WOULD BE LOW SO DID NOT INCLUDE IN THE TAF.
BY TOMORROW AFTERNOON...EXPECT VFR CONDITIONS AND STEADY NORTHEAST
WINDS...STRONGEST AND POSSIBLY GUSTY AT TIMES FOR THE NEAR-LAKE
TERMINALS.
RC
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE IN TSRA IN THE AREA THROUGH ABOUT 05Z...LOW
CONFIDENCE IN TSRA OVERNIGHT/EARLY THURSDAY.
* LOW-MEDIUM CONFIDENCE IN WIND TRENDS AFTER AREA OF SHRA/TSRA
PASSES LATE TONIGHT THROUGH COLD FRONT PASSAGE THURSDAY MORNING.
* LOW CONFIDENCE IN MVFR CIGS THURSDAY MORNING.
RC
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR. NORTHEAST WINDS.
SATURDAY...VFR. EASTERLY WINDS.
SUNDAY THROUGH TUESDAY...VFR.
RC
&&
.MARINE...
202 PM CDT
A COLD FRONT EXTENDED FROM NORTHERN QUEBEC SW ACROSS E LAKE
SUPERIOR...N WI AND S MN AT MID AFTERNOON. THIS COLD FRONT WILL
CONTINUE TO MOVE SE...REACHING N LAKE MI THIS EVENING AND S LAKE
MI THU MORNING....SHIFTING WINDS TO OUT OF THE NW AND N. AS THE
COLD FRONT MOVES OFF TO THE SE DURING THU HIGH PRESSURE WILL MOVE
ESE TO ONTARIO AND THE UPPER MIDWEST. THE HIGH THEN GRADUALLY
SHIFTS SE AND WILL BE OVER QUEBEC...THE GREAT LAKES AND THE OH
VALLEY BY SAT MORNING AND THE MID ATLANTIC SEABOARD AND S
APPALACHIANS BY MON MORNING.
HEIGHT OUTPUT BY LOCALLY RUN WAVE MODEL WOULD APPEAR TO BE LOW
GIVEN MODERATELY STRONG N WINDS THOUGH LOCAL OUTPUT IN LINE WITH
GLERL PRODUCED WAVE HEIGHTS. HOWEVER...WAVE GROWTH WILL BE
LIMITED AS THE AIR MASS BEHIND THE COLD FRONT IS STILL WARM
ENOUGH FOR A TEMPERATURE INVERSION AT THE LAKE SURFACE WHICH WILL
LIMIT MOMENTUM TRANSFER ALL THE WAY DOWN TO THE AIR/WATER
INTERFACE.
TRS
&&
.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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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
[top]
Area Forecast Discussion
National Weather Service Lincoln IL
901 PM CDT Wed Aug 21 2013
.DISCUSSION...
ISSUED 900 PM CDT Wed Aug 21 2013
The line of showers and storms along the cold front has become
more broken up across N Iowa into SW Wisc, which is the area of
storms that is expected to drop into central IL late tonight. The
NCEP 4km WRF from 12z was very aggressive with storms all along
the front after midnight, with storms in pia by 07z. The
nam/gfs/ecmwf/canadian all agree on a slower arrival of storms,
and that is the general forecast progression we will follow in the
grids. we have chance pops to south of peoria between 06z-12z. I
expect to keep at least some area of chance pops north of
peoria...but may trim the southern extent of the chance and slight
chance pops.
Better chances of precip coverage appears to be with storm
redevelopment along the front Thurs afternoon when we warm to
convective temps. We have our widest coverage of chance pops in
the grids across central and southeast IL during the afternoon,
with more narrowed chc pops along the front closer to I-74 in the
morning. Still, with the lack of a low level jet from the south
and weaker 500mb shortwaves indicated tomorrow, we do not expect
strong/severe storms, and actually a more limited coverage of
precip...thus only chance pops instead of likely.
Southerly wind flows will continue all night ahead of the front,
keeping a steady supply of upper 60s dewpoints feeding into the
area. Some light fog may develop later tonight as lows drop into
the upper 60s, but not enough to be a major concern.
Will make minor updates to weather, pops and sky grids. The
remainder of the forecast looks on track through tomorrow. Updated
info will be available shortly.
Shimon
&&
.AVIATION...
ISSUED 652 PM CDT Wed Aug 21 2013
The cold front will progress into central IL late tonight, with a
line of showers and a few thunderstorms still active around
sunrise. The HRRR agrees with the nam/gfs solutions of a weakening
trend in the storms as the front arrives near pia toward 12z. The
primary forcing for storms looks to be farther north in Wisconsin
and farther west in Iowa. Our area will be in a bit of a lull zone
between focus areas for storms. Therefore, I went with only vcsh
late tonight into Thurs morning. The 4km WRF NCEP output is
indicating some afternoon redevelop of a line of storms as the
front drops south toward spi/dec/cmi. So I went with vcts for all
taf sites for afternoon storm chances.
Winds will eventually shift from southwest tonight to a westerly
direction after the frontal passage. I let the storm chances drive
the addition of new lines to the taf, instead of the wind shift
with winds less than 10kt.
A brief period of mvfr fog may develop again tonight as winds
decrease just ahead of the cold front. I did not include any
tempos for fog with this issuance, but will watch observation
trends for any needed adjustments in the fog forecast.
Shimon
&&
.PREV DISCUSSION...
ISSUED 245 PM CDT Wed Aug 21 2013
SHORT TERM...Tonight through Saturday night
A cold front over nw WI, se MN and central NE will be pushed se
through central IL Thursday and into se IL Thu evening as a short
waves over the southern Canadian prairies moves into the upper great
lakes region Thu morning. This will bring isolated to scattered showers
and thunderstorms from i-74 north later tonight and across rest of
central IL Thursday and lingering over southeast IL Thu night
especially. Nudged pops up a bit to 30-40% range on Thu and highest
over ne areas. SPC has slight risk of severe storms into this evening
over much of WI, ne IA and se MN where better wind shear and instability
will be. Frontal boundary weakens as it pushes southward through
IL Thu and upper level dynamics are weakening too. Dewpoints in
the mid to upper 60s this afternoon and so lows will be milder in
the upper 60s tonight in more humid airmass south of the front. Patchy
fog could develop in southeast IL again later tonight/early Thu
morning as convective clouds over IA will be slower to move into se
IL. Dewpoints in the lower 70s pool along the boundary over
central IL Thursday so this will be the most humid day of the
week. Highs in the upper 80s from I-74 north and around 90F south
where afternoon heat indices peak in the mid 90s.
Have 20-40% pops Thursday night from I-72 south mainly in the
evening as frontal boundary continues pushing through se IL. Think
convection will be more widespread in the afternoon/early evening
hours along frontal boundary and diminish by overnight Thursday night.
Lows Thu night in the low to mid 60s with upper 60s in southeast
IL where drier air takes longer to work into behind the front.
1022 mb high pressure over the southern Canadian Rockies settles
into the great lakes region Friday and returns mostly sunny skies
and dry conditions along with less humid air across the area.
Nudged highs up a degree or two into the mid to upper 80s due to
models not as cool with 850-925 mb temps and dryer air mass easier
to heat up. Friday night will be the coolest night with lows in
the upper 50s and lower 60s, coolest over ne areas.
High pressure strengthens to 1026 mb as it drifts into the eastern
great lakes Saturday and upper level ridge starts to build back
into IL. Highs in the mid to upper 80s again Saturday and starting
to get more humid again.
LONG TERM...Sunday through Wednesday
Heat and humidity return to central/se IL during early and middle
part of next week as subtropical mid/upper level ridge strengthens
over the mid ms valley early next week. Nudged highs up a bit
hotter during this time frame with highs near 90F Sunday and low
to mid 90s Mon-Wed. Convection chances should stay less than 20%
over IL with strong ridge anchored nearby...so drought conditions
may expand over the region during the next week.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
658 PM CDT WED AUG 21 2013
.DISCUSSION...
304 PM CDT
THE MAIN FORECAST CONCERN IN THE SHORT TERM WILL BE TIMING THE BEST
CHANCES FOR SCT SHOWER AND THUNDER ACTIVITY TONIGHT INTO THURSDAY.
THEREAFTER...TEMPERATURES WILL BE THE PRIMARY CONCERN...WITH A GOOD
POTENTIAL FOR ANOTHER SEVERAL DAY PERIOD OF WELL ABOVE NORMAL
WEATHER LATER THIS WEEKEND INTO NEXT WEEK.
A POTENT AREA OF LOW PRESSURE ACROSS THE HUDSON BAY AND NORTHERN
QUEBEC...IS BEING FUELED BY A ENHANCED BELT OF 110+ KT UPPER LEVEL
WESTERLIES ENCOMPASSING MUCH OF SOUTHERN CANADA. AT THE SURFACE...AN
ASSOCIATED COLD FRONTAL BOUNDARY IS NOW DROPPING SOUTHWARD ACROSS
THE UPPER MIDWEST AND NORTHERN PLAINS. THIS FRONTAL BOUNDARY IS
EXPECTED TO BE THE MAIN DRIVER FOR OUR BEST CHANCES OF CONVECTION
FOR AT LEAST THE NEXT 7 DAYS.
THUNDERSTORMS WILL LIKELY CONTINUE TO FIRE UP THROUGH THE AFTERNOON
TO OUR NORTH ACROSS NORTHERN WISCONSIN AND POINTS SOUTHWESTWARD AS
THIS COLD FRONT INTERACTS WITH AN UNSTABLE WARM SECTOR AIR MASS. A
SEVERE WEATHER THREAT IS HIGHLIGHTED BY THE SPC ACROSS THIS REGION.
HOWEVER...THE SEVERE THREAT WILL DIMINISH THROUGH THE EVENING AS THE
COLD FRONT MOVES TOWARDS NORTHERN ILLINOIS.
ALTHOUGH MUCH OF THE MID AND UPPER-LEVEL SUPPORT IS EXPECTED TO
REMAIN WELL NORTH OF THE AREA...ASSOCIATED WITH THE STRONGER BELT OF
UPPER LEVEL FLOW....WATER VAPOR IMAGERY DOES INDICATE THE PRESENCE
OF SOME PERTURBED MID-LEVEL FLOW...WITH A SERIES OF MID-LEVEL
DISTURBANCES ROTATING ALONG THE WESTERN AND NORTHERN PERIPHERY OF A
MID/UPPER-LEVEL ANTICYCLONE ACROSS THE CENTRAL AND SOUTHERN PLAINS.
IT APPEARS THAT SOME OF THESE DISTURBANCES MAY COMPLEMENT SOME OF
THE MODEST FRONTAL SCALE FORCING/MOISTURE CONVERGENCE ALONG AND NEAR
THE FRONTAL BOUNDARY TONIGHT TO HELP KEEP AT LEAST SOME WIDELY
SCATTERED TO SCATTERED STORMS GOING ACROSS THE AREA TONIGHT.
ALTHOUGH THE THREAT FOR SEVERE STORMS WILL BE VERY LOW...THERE COULD
BE A FEW GUSTY WINDS WITH SOME OF THE STRONGER STORMS. IT ALSO
APPEARS THAT THESE STORMS WILL BE CAPABLE OF PRODUCING BRIEF
TORRENTIAL DOWNPOURS OVERNIGHT. GUIDANCE CONTINUES TO INDICATE
PRECIPITABLE WATER VALUES TOPPING OUT AT OR ABOVE 1.65
INCHES...WHICH SHOULD ALLOW FOR GO EFFICIENT RAINFALL IN THE
STRONGEST SHOWERS. WITH THIS IN MIND I DID UP QPF AMOUNTS
TONIGHT...ESPECIALLY ACROSS NORTHEASTERN ILLINOIS.
IT APPEARS THAT SHOWERS AND THUNDERSTORMS MAY REGENERATE/CONTINUE
ACROSS THE AREA THURSDAY MORNING...AS ADDITIONAL DISTURBANCES MOVE
TOWARDS THE AREA AND INTERACT WITH THE SURFACE BOUNDARY. THESE
STORMS COULD AGAIN POSS AN ISOLATED HEAVY RAIN THREAT.
OTHERWISE...THE SURFACE FRONT SHOULD TOWARDS MY SOUTHERN COUNTIES
DURING THE AFTERNOON...PLACING THE MAIN THREAT FOR CONVECTION ACROSS
MY SOUTHERN COUNTIES LATER THURSDAY. IN SPITE OF THIS...GUIDANCE HAS
BEEN INSISTENT IN SOME ADDITIONAL ISOLATED TO SCATTERED CONVECTION
DEVELOPING ACROSS NORTHEASTERN ILLINOIS DURING AT LEAST THE EARLY
AFTERNOON...LIKELY IN ASSOCIATION WITH A DECENT BOUNDARY LAYER
CONVERGENCE ALONG A LAKE BREEZE BOUNDARY. WITH THIS IN MIND...IT DID
KEEP SOME SLIGHT CHANCE POPS GOING INTO THE EARLY AFTERNOON ACROSS
FAR NORTHERN ILLINOIS. OTHERWISE...THE CONVECTIVE THREAT SHOULD COME
TO AN END AREA-WIDE BY EARLY THURSDAY EVENING. THIS LOOKS TO BE THE
ONLY DECENT CHANCE FOR PRECIP DURING THE REST OF THE FORECAST
PERIOD.
SURFACE HIGH PRESSURE BUILDS ACROSS THE GREAT LAKES FOR FRIDAY. THIS
SHOULD RESULT IN ONSHORE FLOW FRIDAY...WITH COOLER TEMPERATURES
INTO SATURDAY.
THIS COOL DOWN WILL BE VERY SHORT LIVED...HOWEVER...AS THE SURFACE
HIGH QUICKLY SHIFTS EASTWARD. ONCE THIS OCCURS...A VERY WARM AIR MASS
IS EXPECTED TO DEVELOP ACROSS THE PLAINS AND THEN SHIFT EASTWARD
ACROSS THE AREA LATER THIS WEEKEND AND INTO...AT LEAST...THE MIDDLE
OF NEXT WEEK. THE MODEL GUIDANCE IS FORECASTING A CLASSIC
MID/UPPER-LEVEL DOME OF OF HIGH PRESSURE...WHICH LOOKS TO ENCOMPASS
MUCH OF THE CENTRAL CONUS. THIS SHOULD RESULT IN A DRY WEATHER
PATTERN AS THE MAIN STORM TRACK/RIDGE RUNNERS REMAINING WELL NORTH
OF THE AREA. THE MAIN STORY WITH THIS WEATHER PATTERN WILL BE THE
VERY WARM TEMPERATURES...ESPECIALLY SUNDAY THROUGH AT LEAST TUESDAY.
GUIDANCE CONTINUES IN GOOD AGREEMENT WITH PROGGED 850 AND 925 MB
TEMPERATURES OF 20-22 AND 26-28 DEGREES CELSIUS...RESPECTIVELY. THIS
COULD SUPPORT TEMPERATURES WELL INTO THE 90S...POSSIBLY AS HIGH AS
MID TO UPPER 90S...ESPECIALLY MONDAY AND TUESDAY. WITH THIS IN
MIND...I WARMED TEMPERATURES OVER GUIDANCE...INDICATING LOW TO MID
90S. RECORD HIGHS FOR MONDAY AND TUESDAY ARE 97 DEGREES AT BOTH
CHICAGO AND ROCKFORD.
UNCERTAINTY INCREASES BY WEDNESDAY...WITH THE MODELS A BIT UNCERTAIN
ON IF A COOL FRONT MAKES IT ACROSS NORTHERN ILLINOIS. THEREFORE...IT
DID NOT MAKE ANY SIGNIFICANT CHANGES FOR WEDNESDAY.
HOWEVER...TEMPERATURES COULD AGAIN JUMP ABOVE 90
DEGREES...DEPENDING ON THE TIMING AND ACTUAL EXISTENCE OF THIS
COLD FRONT.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* SHRA/TSRA POTENTIAL LATE TONIGHT/EARLY THURSDAY.
* WIND TRENDS LATE TONIGHT THROUGH THURSDAY MORNING WITH SHRA/TSRA
COMPLEX AND THEN COLD FRONT PASSAGE.
* CHANCE OF MVFR CIGS THURSDAY MORNING FOR A SHORT PERIOD BEHIND
COLD FRONT.
RC
//DISCUSSION...UPDATED 00Z...
UNCERTAIN AND LOW CONFIDENCE CONVECTIVE FORECAST LATE TONIGHT INTO
EARLY THURSDAY...WITH SHRA/TSRA POTENTIAL STILL EXPECTED TO BE
TIED IN SOME FASHION TO TSRA COMPLEX OVER WISCONSIN AND POSSIBLY
ACTIVITY OVER IOWA AND SOUTHERN MN AS WELL. INSTABILITY WILL BE ON
THE DOWNSWING BY THE TIME ANY TSRA APPROACH THE TERMINALS...SO A
WEAKENING TREND WOULD BE EXPECTED. NONETHELESS HAVE MAINTAINED
TIMING FROM 22Z UPDATE. IF TSRA DIRECTLY AFFECT THE
TERMINALS...MVFR OR LOWER VSBY IS POSSIBLE. ALL OF THE ACTIVITY
IS WELL AHEAD OF A COLD FRONT THAT WILL BE APPROACHING THURSDAY
MORNING. WINDS BEHIND ANY TSRA SHOULD TURN WEST TO
NORTHWEST...BUT MAY EVEN TREND BACK SOUTHWEST FOR A TIME PRIOR TO
THE COLD FRONT.
DO NOT ANTICIPATE ANY MORE SHRA/TSRA WITH FRONT DUE TO
PREFRONTAL CONVECTION...SO MAIN IMPACT WILL BE WIND SHIFT TO
NORTH-NORTHWEST AND THEN QUICKLY FLIPPING OVER TO NORTHEAST WITH A
HYBRID LAKE BREEZE. GUIDANCE INDICATES HIGH MOISTURE AT OR BELOW
2000 FT AGL FOR A FEW HOURS AFTER THE FRONTAL PASSAGE BEFORE
CLEARING...SO THERE COULD BE A PERIOD OF LOW-MID MVFR CIGS BUT DO
NOT HAVE HIGH CONFIDENCE IN THIS OCCURRING. ITS NOT OUT OF THE
QUESTION FOR THERE TO BE A FEW SHRA/TSRA POPPING UP ON THE LAKE
BREEZE...BUT COVERAGE WOULD BE LOW SO DID NOT INCLUDE IN THE TAF.
BY TOMORROW AFTERNOON...EXPECT VFR CONDITIONS AND STEADY NORTHEAST
WINDS...STRONGEST AND POSSIBLY GUSTY AT TIMES FOR THE NEAR-LAKE
TERMINALS.
RC
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* LOW-MEDIUM CONFIDENCE IN TSRA IN THE AREA LATE TONIGHT...LOW CONFIDENCE
IN DIRECT TERMINAL IMPACTS.
* LOW-MEDIUM CONFIDENCE IN WIND TRENDS AFTER AREA OF SHRA/TSRA
PASSES LATE TONIGHT THROUGH COLD FRONT PASSAGE THURSDAY MORNING.
* LOW CONFIDENCE IN MVFR CIGS
RC
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR. NORTHEAST WINDS.
SATURDAY...VFR. EASTERLY WINDS.
SUNDAY THROUGH TUESDAY...VFR.
RC
&&
.MARINE...
202 PM CDT
A COLD FRONT EXTENDED FROM NORTHERN QUEBEC SW ACROSS E LAKE
SUPERIOR...N WI AND S MN AT MID AFTERNOON. THIS COLD FRONT WILL
CONTINUE TO MOVE SE...REACHING N LAKE MI THIS EVENING AND S LAKE
MI THU MORNING....SHIFTING WINDS TO OUT OF THE NW AND N. AS THE
COLD FRONT MOVES OFF TO THE SE DURING THU HIGH PRESSURE WILL MOVE
ESE TO ONTARIO AND THE UPPER MIDWEST. THE HIGH THEN GRADUALLY
SHIFTS SE AND WILL BE OVER QUEBEC...THE GREAT LAKES AND THE OH
VALLEY BY SAT MORNING AND THE MID ATLANTIC SEABOARD AND S
APPALACHIANS BY MON MORNING.
HEIGHT OUTPUT BY LOCALLY RUN WAVE MODEL WOULD APPEAR TO BE LOW
GIVEN MODERATELY STRONG N WINDS THOUGH LOCAL OUTPUT IN LINE WITH
GLERL PRODUCED WAVE HEIGHTS. HOWEVER...WAVE GROWTH WILL BE
LIMITED AS THE AIR MASS BEHIND THE COLD FRONT IS STILL WARM
ENOUGH FOR A TEMPERATURE INVERSION AT THE LAKE SURFACE WHICH WILL
LIMIT MOMENTUM TRANSFER ALL THE WAY DOWN TO THE AIR/WATER
INTERFACE.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion
National Weather Service Lincoln IL
652 PM CDT Wed Aug 21 2013
.DISCUSSION...
ISSUED 245 PM CDT Wed Aug 21 2013
SHORT TERM...Tonight through Saturday night
A cold front over nw WI, se MN and central NE will be pushed se
through central IL Thursday and into se IL Thu evening as a short
waves over the southern Canadian prairies moves into the upper great
lakes region Thu morning. This will bring isolated to scattered showers
and thunderstorms from i-74 north later tonight and across rest of
central IL Thursday and lingering over southeast IL Thu night
especially. Nudged pops up a bit to 30-40% range on Thu and highest
over ne areas. SPC has slight risk of severe storms into this evening
over much of WI, ne IA and se MN where better wind shear and instability
will be. Frontal boundary weakens as it pushes southward through
IL Thu and upper level dynamics are weakening too. Dewpoints in
the mid to upper 60s this afternoon and so lows will be milder in
the upper 60s tonight in more humid airmass south of the front. Patchy
fog could develop in southeast IL again later tonight/early Thu
morning as convective clouds over IA will be slower to move into se
IL. Dewpoints in the lower 70s pool along the boundary over
central IL Thursday so this will be the most humid day of the
week. Highs in the upper 80s from I-74 north and around 90F south
where afternoon heat indices peak in the mid 90s.
Have 20-40% pops Thursday night from I-72 south mainly in the
evening as frontal boundary continues pushing through se IL. Think
convection will be more widespread in the afternoon/early evening
hours along frontal boundary and diminish by overnight Thursday night.
Lows Thu night in the low to mid 60s with upper 60s in southeast
IL where drier air takes longer to work into behind the front.
1022 mb high pressure over the southern Canadian Rockies settles
into the great lakes region Friday and returns mostly sunny skies
and dry conditions along with less humid air across the area.
Nudged highs up a degree or two into the mid to upper 80s due to
models not as cool with 850-925 mb temps and dryer air mass easier
to heat up. Friday night will be the coolest night with lows in
the upper 50s and lower 60s, coolest over ne areas.
High pressure strengthens to 1026 mb as it drifts into the eastern
great lakes Saturday and upper level ridge starts to build back
into IL. Highs in the mid to upper 80s again Saturday and starting
to get more humid again.
LONG TERM...Sunday through Wednesday
Heat and humidity return to central/se IL during early and middle
part of next week as subtropical mid/upper level ridge strengthens
over the mid ms valley early next week. Nudged highs up a bit
hotter during this time frame with highs near 90F Sunday and low
to mid 90s Mon-Wed. Convection chances should stay less than 20%
over IL with strong ridge anchored nearby...so drought conditions
may expand over the region during the next week.
07
&&
.AVIATION...
ISSUED 652 PM CDT Wed Aug 21 2013
The cold front will progress into central IL late tonight, with a
line of showers and a few thunderstorms still active around
sunrise. The HRRR agrees with the nam/gfs solutions of a weakening
trend in the storms as the front arrives near pia toward 12z. The
primary forcing for storms looks to be farther north in Wisconsin
and farther west in Iowa. Our area will be in a bit of a lull zone
between focus areas for storms. Therefore, I went with only vcsh
late tonight into Thurs morning. The 4km WRF NCEP output is
indicating some afternoon redevelop of a line of storms as the
front drops south toward spi/dec/cmi. So I went with vcts for all
taf sites for afternoon storm chances.
Winds will eventually shift from southwest tonight to a westerly
direction after the frontal passage. I let the storm chances drive
the addition of new lines to the taf, instead of the wind shift
with winds less than 10kt.
A brief period of mvfr fog may develop again tonight as winds
decrease just ahead of the cold front. I did not include any
tempos for fog with this issuance, but will watch observation
trends for any needed adjustments in the fog forecast.
Shimon
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
259 PM CDT TUE AUG 20 2013
.DISCUSSION...
259 PM...MAIN FORECAST CONCERN/CHALLENGES ARE PRECIP COVERAGE/
TIMING WITH A COLD FRONT LATE WEDNESDAY INTO THURSDAY. CONCERNS
INTO THE EXTENDED INCLUDE POTENTIAL FOR A PROLONG PERIOD OF VERY
WARM/HOT WEATHER EARLY/MID NEXT WEEK.
IN THE SHORT TERM...SIMILAR TO MONDAY AFTERNOON...AN AREA OF
CIRRUS ALONG WITH A SCT/BKN CU FIELD HAS LIKELY HINDERED HIGH
TEMPS A DEGREE OR TWO WITH MOST AREAS IN THE MID 80S. WINDS ARE
BIT STRONGER WITH SOME GUSTS TO 20 MPH ACROSS NORTHERN IL. PATCHY
FOG DEVELOPED OVERNIGHT/THIS MORNING AND WHILE THERE IS LITTLE
CHANGE TO THE AIRMASS WITH DEWPOINTS STILL IN THE LOWER/MID 60S...
THE GRADIENT WILL BE SLIGHTLY STRONGER TONIGHT. THUS CONFIDENCE
REGARDING LIGHT FOG/HAZE ISN/T PARTICULARLY HIGH BUT OPTED TO
INCLUDE PATCHY FOG EXCEPT FOR THE IMMEDIATE METRO AREA/CHICAGO.
THE GRADIENT TIGHTENS A BIT MORE WEDNESDAY AND EXPECT WIND GUSTS
INTO THE 20-25 MPH RANGE ACROSS NORTHERN IL. THERMALLY...TEMPS DO
WARM A FEW DEGREES ALOFT AND EVEN WITH AN EXPECTED CU FIELD...
THINK MOST AREAS WILL TAG 90 WEDNESDAY AFTERNOON AND WIND SPEEDS
SHOULD BE STRONG ENOUGH TO PREVENT ANY LAKE BREEZE.
A COLD FRONT WILL MOVE SOUTH ACROSS THE MIDWEST/LAKES REGION
WEDNESDAY NIGHT AND THROUGH MUCH OF THE CWA DURING THE MID/LATE
MORNING OF THURSDAY. THIS MAKES FOR A TRICKY HIGH TEMP FORECAST AS
HIGHS IN THE SOUTH COULD EASILY BE IN THE UPPER 80S...WHILE WINDS
TURNING OFF THE LAKE WILL PROBABLY HOLD TEMPS STEADY MID DAY AND
THEN FALLING TEMPS INTO THE MID/LATE AFTERNOON. CONVECTION ALONG
AND AHEAD OF THE FRONT WEDNESDAY EVENING WILL LIKELY BE IN SOME
FORM OF DECAY AS IT SPREADS INTO FAR NORTHERN IL AROUND MIDNIGHT
AND CONTINUES SOUTH OVERNIGHT. UPPER LEVEL SUPPORT/DYNAMICS ALL
BEGIN TO WEAKEN INTO THURSDAY AND PRECIP CHANCES OR MORE
SPECIFICALLY QPF AMOUNTS ARE LOOKING RATHER MEAGER WITH PERHAPS
SOME AREAS REMAINING DRY. DIURNAL DEVELOPMENT ON THE FRONT IN THE
AFTERNOON COULD BRING ADDITIONAL PRECIP BUT PERHAPS ACROSS THE
FAR SOUTHERN CWA BY THAT TIME.
THE FASTER FROPA TIMING DRYS THINGS OUT THURSDAY NIGHT WITH HIGH
PRESSURE BUILDING ACROSS THE WESTERN LAKES FRIDAY AND SATURDAY.
THIS ENDS ANY CHANCE OF PRECIP DURING THIS TIME AND MUCH DRIER AIR
WILL SPREAD ACROSS THE AREA FRIDAY. IN FACT...SOUNDINGS WOULD
SUGGEST DEWPOINTS COULD DROP INTO THE 40S...MAYBE EVEN UPPER 30S
WITH AFTERNOON MIXING AND THUS HAVE SIGNIFICANTLY LOWERED DEWPOINTS
FRIDAY AFTERNOON.
THIS HIGH BEGINS TO MOVE EAST SATURDAY NIGHT AND SUNDAY AS
SOUTHERLY FLOW RETURNS. THE GENERAL TREND OF A SIGNIFICANT WARM
UP THAT MAY PERSIST FOR SEVERAL DAYS IS STILL ON TRACK...WITH ONE
EXCEPTION...THE 00Z ECMWF FROM THIS MORNING. THIS RUN SHOWED A
STRONG COLD FRONT PUSHING SOUTH INTO THE AREA MONDAY NIGHT INTO
TUESDAY. THIS FRONT STILL MAKES A RUN AT NORTHERN IL BY MIDWEEK
BUT IS WEAKER AND SLOWER WITH THE NEW 12Z ECMWF. MEANWHILE THE
GEM/GFS CONTINUE TO MAINTAIN DRY SOUTHERLY FLOW INTO MONDAY/
TUESDAY. GIVEN HOW DRY IT HAS BEEN AND APPEARS TO REMAIN...WILL
NOT INTRODUCE ANY POPS DURING THIS TIME PERIOD THIS FAR OUT.
RISING TEMPS ON THE BACK SIDE OF THE HIGH SEEM SOMEWHAT SLOWED BY
THE DEPARTING HIGH. THUS...WHILE TEMPS COULD REACH 90 SUNDAY...
FEEL MORE COMFORTABLE HOLDING IN THE UPPER 80S WITH TEMPS REACHING
90 PERHAPS LOWER 90S MANY LOCATIONS ON MONDAY. GIVEN THE SOMEWHAT
LOWER CONFIDENCE REGARDING THE FROPA POTENTIAL ON TUESDAY...HAVE
MAINTAINED HIGHS ONLY IN THE 80S FOR NOW. CMS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* NONE.
KJB
//DISCUSSION...UPDATED 18Z...
AN EXPANSIVE AREA OF SURFACE HIGH PRESSURE CONTINUES TO DOMINATE
ACROSS THE SOUTHERLY GREAT LAKES...ACROSS THE OHIO VALLEY AND THE
CENTRAL ATLANTIC COAST. THIS FEATURE WILL MOVE LITTLE OVER THE NEXT
24 HOURS. HOWEVER...A COLD FRONT IS EXPECTED TO BEGIN DROPPING
SOUTHWARD ACROSS THE NORTHERN WISCONSIN DURING THE DAY ON WEDNESDAY.
WITH A SLIGHTLY STRONGER PRESSURE GRADIENT DEVELOPING ACROSS THE
AREA...SOUTH-SOUTHWEST WINDS WILL INCREASE A BIT INTO
WEDNESDAY...WITH SOME GUSTS UP TO AROUND 18-20 KT DURING THE
AFTERNOON. THIS SHOULD KEEP THE THREAT OF ANY LAKE BREEZES LOW
THROUGH THE PERIOD.
OVERALL...THE PERIOD APPEARS TO REMAIN QUIET THROUGH WEDNESDAY
AFTERNOON. THE ONLY WEATHER ISSUE WILL BE ANOTHER DECENT POTENTIAL
FOR SOME GROUND FOG LATER TONIGHT AT ROCKFORD AND DUPAGE AFTER 09
UTC. THIS HAS OCCURRED THE LAST FEW MORNINGS...AND WITH LITTLE
OVERALL CHANGE EXPECTED TONIGHT...I WOULD EXPECT THAT SOME SHALLOW
FOG MAY AGAIN DEVELOP IN THESE LOCATIONS. THEREFORE...I ADDED A
TEMPO TO BOTH SITES FOR MIFG LATER TONIGHT.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.
KJB
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
WEDNESDAY NIGHT...CHC TSRA.
THURSDAY...CHC TSRA.
FRIDAY...VFR.
SATURDAY...SLT CHC TSRA.
SUNDAY...VFR.
MONDAY...VFR.
BMD
&&
.MARINE...
259 PM CDT
THE PRESSURE GRADIENT WILL CONTINUE TO TIGHTEN OVER THE LAKE DUE TO
DEEP LOW PRESSURE WELL TO THE NORTH AND AN APPROACHING COLD FRONT.
SOUTH/SOUTHWEST WINDS WILL PEAK ON WEDNESDAY...WITH SUSTAINED WINDS
ON THE NORTH HALF APPROACHING THE MID 20S KT RANGE. DESPITE STABLE
CONDITIONS...THIS SHOULD YIELD GUSTS TO 30 KT. WINDS ON THE SOUTH
HALF WILL INCREASE TO 15 TO 25 KT. THEN A FAIRLY STRONG COLD FRONT
WILL CROSS THE LAKE WEDNESDAY NIGHT THROUGH THURSDAY MORNING...WITH
WINDS TURNING NORTHERLY AND INCREASING. GUIDANCE HAS COME INTO LINE
TO SUPPORT A PERIOD OF NORTHERLY WINDS TO AROUND 25 KT ON THE SOUTH
HALF THURSDAY INTO THURSDAY EVENING BEFORE WINDS BEGIN TO DIMINISH
AS HIGH PRESSURE SPREADS IN FROM THE NORTH. THE STRONG NORTHERLY
FLOW AND HIGHER WAVES WILL LIKELY NECESSITATE A SMALL CRAFT ADVISORY
FOR ALL THE ILLINOIS AND INDIANA NEARSHORE ZONES THURSDAY
AFTERNOON THROUGH FRIDAY AFTERNOON. WINDS WILL BE FAIRLY LIGHT MOST
OF FRIDAY THROUGH EARLY SATURDAY BUT THEN SOUTHERLY WINDS WILL
INCREASE AGAIN ESPECIALLY ON THE NORTH HALF AS THE HIGH QUICKLY
SHIFTS EAST AND A WARM FRONT LIFTS NORTH.
RC
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion
National Weather Service Lincoln IL
1237 PM CDT Tue Aug 20 2013
.DISCUSSION...
ISSUED 1026 AM CDT Tue Aug 20 2013
9 AM surface map showed high pressure centered over the mid-
Atlantic coast, with ridging extending west into southern IL and
MO. This put most of central IL in a very light wind regime,
though light return southerly flow on the back side of the ridge had
pushed east to the I-55 corridor. Aloft, water vapor imagery
indicated a cutoff mid-level low circulating over west central IL
and an additional shortwave in western KY. 12Z ILX sounding was
quite dry in the mid levels and high-res models focus better
ascent ahead of the KY shortwave as it drifts northeast this
afternoon. A very isolated shower or storm is possible in the far
southeast this afternoon where RAP soundings show little to no cap in
place, however feel if anything does develop should be confined
farther east into southern IN and have maintained a dry forecast.
Otherwise, mostly sunny skies will dominate the CWA today. Mixing
to around 850MB supports highs of 85-89F.
&&
.AVIATION...
ISSUED 1236 PM CDT Tue Aug 20 2013
High pressure ridge finally shifting east of the region, and
allowing light southerly flow to develop which will persist
through 18Z/Wed. SCT diurnal cu with bases around 5K Ft will
briefly go BKN this afternoon, but predominant SCT conditions
should prevail. Similar cloud trends are expected to develop again
by late morning Wed. Some brief MVFR visibility restrictions could
develop within a few hours of sunrise however this should not be
as widespread as recent days due to ridge axis well east of the area.
25
&&
.PREV DISCUSSION...
ISSUED 225 AM CDT Tue Aug 20 2013
Illinois remains on the periphery of high pressure that was
centered near the mid-Atlantic coast early this morning. Have seen
some high clouds rotating around an upper level circulation that
was very evident on water vapor imagery, dropping along the
Mississippi River in far western Illinois.
Primary forecast focus remains on rain chances later this week,
along with extended period of very warm conditions.
SHORT TERM...Today through Thursday...
Upper circulation to continue to carve out a broad trough over
Illinois today, with model guidance showing some potential for a
small closed circulation forming by late tonight before the trough
swings eastward. Currently appears that any rain with this feature
will remain to our east. Temperatures continue a slow but steady
rise and should reach the upper 80s most areas by Wednesday.
Main focus shifts to an upper wave moving across southwest Canada
early this morning. Broad east-west ridging over the southern U.S.
should start to amplify across the Rockies Wednesday night,
allowing the wave to dig more as it sweeps through the Great Lakes
region. The guidance is generally in agreement with the resulting
surface front pushing all the way through the state on Thursday.
Still some question as to whether or not this is overly aggressive
for this time of year, especially the NAM solution as it brings
temps all the way down to the lower 50s by Friday morning behind
the front. Rain-wise, have introduced some slight chance PoPs
after midnight Wednesday night across the northern CWA, and a
broad area of 30% chances east of a Macomb to Lawrenceville line
on Thursday. Have lingered some slights into Thursday night and
Friday, as the ECMWF model shows some hints of the front pushing
back northeast.
LONG TERM...Friday through Monday...
Broad dome of high pressure aloft to cover most of the country
this weekend and early next week. Convective systems traversing
the northern flank of the ridge should stay to our north, with
core of the upper high nearly overhead. After a brief cool down on
Friday, gradual warming will take place through early next week,
with highs near 90 becoming more common. Humidity levels not
expected to get out of hand due to the recent dry conditions, so
heat index values will only be a few degrees warmer than the
observed temperatures.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1051 AM CDT TUE AUG 20 2013
.DISCUSSION...
347 AM CDT
NEAR TERM FORECAST CONCERNS FOCUS ON CONTINUED SLOW WARMING TREND IN
TEMPERATURES TODAY AND WEDNESDAY. COLD FRONT SAGGING INTO THE AREA
EARLY THURSDAY...AND ASSOCIATED POTENTIAL FOR SHOWERS/THUNDERSTORMS
ALONG AND AHEAD OF THIS FRONT WEDNESDAY NIGHT INTO THURSDAY BECOME
THE MAIN FOCUS IN THE MID-WEEK PERIOD. LONGER TERM...EXPECT A BIT OF
A COOL DOWN BEHIND THE FRONT FRIDAY AND SATURDAY...THEN THE
POTENTIAL FOR A LATE-AUGUST HEAT WAVE BY EARLY NEXT WEEK AS UPPER
RIDGE BUILDS OVER THE REGION.
EARLY MORNING SURFACE ANALYSIS DEPICTS HIGH PRESSURE ALONG/OFF THE
MID-ATLANTIC COAST REGION...WITH WEAKER RIDGING EXTENDING BACK TO
THE WEST ACROSS THE MIDWEST. LIGHT SOUTHERLY FLOW HAD DEVELOPED WEST
OF THE RIDGE...WITH THE WFO LOT CWA GENERALLY ON THE EASTERN
PERIPHERY OF THIS RETURN FLOW ACROSS THE CENTRAL CONUS. ALOFT...IR
SATELLITE LOOP SHOWS A SLOW MOVING MID-UPPER LEVEL CIRCULATION OVER
ILLINOIS...PRODUCING A PATCHY HIGH CIRRUS DECK ACROSS THE AREA. THIS
CIRCULATION WILL CONTINUE TO DRIFT SOUTHEAST ACROSS DOWNSTATE IL AND
EVENTUALLY SOUTHERN INDIANA THROUGH TONIGHT...WITH RELATIVELY DRY
LOW/MID LEVELS IN DVN/ILX 00Z SOUNDINGS SUGGESTING MAINLY JUST SOME
ADDITIONAL PATCHY HIGH CLOUDS WITH THIS FEATURE. AREA OF WARM/MOIST
LOW LEVEL ADVECTION WITH ANOTHER SHORT WAVE OVER WESTERN MINNESOTA
AND IOWA WAS PRODUCING SOME LOWER CLOUDS THIS MORNING...BUT
ORIENTATION OF MOISTURE TRANSPORT SHOULD FOCUS THESE LOWER CLOUDS
FROM IA/MN INTO WI THROUGH TODAY. THUS...PARTLY CLOUDY CONDITIONS
TODAY SHOULD ALLOW CONTINUED WARMING OF TEMPS FROM THE PAST SEVERAL
DAYS. SOUTHWEST FLOW IN LOW LEVELS INCREASES INTO WEDNESDAY AS
STRONGER SHORT WAVE MOVES ALONG THE U.S./CANADIAN BORDER...
MAINTAINING WARM ADVECTION ACROSS THE CWA. VARIOUS MODEL THERMAL
FIELDS AND 925-850MB LOCAL CLIMATOLOGY SUPPORT TEMPS REACHING UPPER
80S IN MOST LOCATIONS TODAY...WITH A FEW MID 80S IN THE FAR
SOUTHEAST. HIGHS WEDNESDAY EXPECTED FROM AROUND 90 IN WARMER
NORTHERN IL SPOTS INCLUDING CITY OF CHICAGO...WITH UPPER 80S IN THE
SOUTHEAST. MINS WILL GENERALLY BE IN THE 60S BOTH TONIGHT AND
WEDNESDAY NIGHT...WITH LOWS ONLY AROUND 70 IN THE CITY...AND MORE
HUMIDITY WEDNESDAY NIGHT AS LOW LEVEL MOISTURE INCREASES AHEAD OF
APPROACHING COLD FRONT. SOUTHWEST WINDS TODAY SHOULD PREVENT THE
LAKE BREEZE FROM AFFECTING MUCH MORE THAN THE IMMEDIATE ILLINOIS
SHORE AREAS...AND STRONGER SOUTHWEST WINDS WEDNESDAY SHOULD PRECLUDE
A LAKE BREEZE ALTOGETHER.
NEXT ITEM OF INTEREST IS THE AFOREMENTIONED COLD FRONT...WHICH
GUIDANCE CONTINUES TO INDICATE WILL SAG INTO FAR NORTHERN ILLINOIS
EARLY THURSDAY MORNING...AND PUSH SOUTH ACROSS THE CWA DURING THE
DAY. MAIN QUESTION WITH THIS FRONT IS WITH THE AMOUNT/COVERAGE OF
SHOWERS AND THUNDERSTORMS THAT MAY OCCUR WITH IT. MAIN UPPER LEVEL
SHORT WAVE AND JET SUPPORT PASSES WELL NORTH OF THE AREA ACROSS
ONTARIO AND THE NORTHERN LAKES WEDNESDAY INTO EARLY THURSDAY...WITH
CONVERGENCE ALONG/AHEAD OF THE LOW LEVEL FRONTAL BOUNDARY THE MAIN
SOURCE OF FORCING FOR STORMS FARTHER SOUTH INTO THE MIDWEST.
THUNDERSTORMS ARE MUCH MORE LIKELY ACROSS PARTS OF MINNESOTA...
WISCONSIN AND MICHIGAN WEDNESDAY AFTERNOON/EVENING...WHERE
INSTABILITY WILL BE MAXIMIZED DUE TO DIURNAL HEATING OF MOIST AXIS
ALONG THE FRONT. WHILE A FEW STORMS COULD MAKE IT INTO FAR NORTHERN
IL DURING THE EVENING OR OVERNIGHT HOURS...THE TIMING WILL BE FAIRLY
UNFAVORABLE FOR SIGNIFICANT COVERAGE AS THE BOUNDARY LAYER COOLS AND
STABILIZES OVERNIGHT. CAN ONLY JUSTIFY CHANCE POPS WEDNESDAY NIGHT
ACROSS THE NORTH...AND DURING THE DAY THURSDAY FARTHER SOUTH ACROSS
THE CWA AS THE FRONT CONTINUES TO DRIFT SOUTH WITHIN A WEAK
SHEAR/WEAK UPPER SUPPORT ENVIRONMENT. SOMEWHAT DIFFUSE FRONT
EVENTUALLY STALLS IN A NORTHWEST-SOUTHEAST ORIENTATION FROM IA INTO
CENTRAL IL THURSDAY NIGHT...AND HAVE MAINTAINED SOME SLIGHT CHANCE
POPS FOR SOME ISOLATED SHRA/TSRA ACROSS THE FAR SOUTH/SOUTHWEST
PARTS OF THE CWA NEAR THE FRONT.
AS THE FRONT PUSHES SOUTH INTO THE CWA THURSDAY...HIGH PRESSURE WILL
BUILD SOUTHEAST ACROSS THE GREAT LAKES REGION. NORTH/NORTHEAST WINDS
WILL BRING COOLER AIR AND ONSHORE WINDS WHICH WILL MAKE FOR SHORT
COOL-DOWN FROM OUR CURRENT MID-WEEK WARMTH...THOUGH WITH TEMPS STILL
NEAR/ABOVE NORMAL IN THE 80-85 RANGE. ONSHORE FLOW MAY LIMIT LAKE
MICHIGAN SHORE SITES TO THE UPPER 70S FRIDAY AND SATURDAY.
LONGER RANGE GUIDANCE CONTINUES TO INDICATE NORTHEASTWARD EXPANSION
OF THE UPPER RIDGE WHICH IS CURRENTLY OVER THE SOUTHWESTERN CONUS
THIS WEEKEND. WITH BUILDING HEIGHTS OVER THE AREA SUNDAY AND THE
SURFACE HIGH PRESSURE MOVING OFF TO THE EAST AND ALLOWING A RETURN
OF SOUTH WINDS...TEMPS SHOULD BEGIN THEIR CLIMB BACK INTO THE UPPER
80S/AROUND 90...POTENTIALLY 90+. HEAT BUILDS INTO MONDAY...THOUGH
MODELS DO SHOW DIFFERENCES IN MAINTAINING THE RIDGE OVERHEAD AS
NEW 00Z ECMWF SHOWS SOME RUN TO RUN INCONSISTENCY AND FLATTENS IT
MORE QUICKLY WITH A SHORT WAVE TROUGH PROPAGATING SOUTHEAST ACROSS
THE GREAT LAKES MONDAY. IN ANY CASE... IT DOES APPEAR THAT A LATE-
AUGUST HEAT WAVE IS IN STORE FOR THE AREA LATE THIS WEEKEND INTO
EARLY NEXT WEEK.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* NONE.
KB
//DISCUSSION...UPDATED 12Z...
THE REGION REMAINS UNDER THE INFLUENCE OF HIGH PRESSURE TO OUR EAST
AND AN APPROACHING COLD FRONT TO THE NORTHWEST. A MODEST SOUTHWEST
GRADIENT WILL DEVELOP BETWEEN THESE FEATURES TODAY...WITH WINDS
PICKING UP THIS MORNING WITH GUSTS INTO THE MID TEENS BY LATE
MORNING AND THROUGH THE AFTERNOON. SOME DIURNAL CUMULUS CLOUDS WILL
DEVELOP WITH BASES AROUND 050 TODAY. BY MID TO LATE THIS
EVENING...EXPECT WINDS TO DIMINISH BACK BELOW 10 KT. WINDS WILL BE A
LITTLE GUSTIER DURING THE DAY WEDNESDAY...WITH GUSTS INTO THE HIGH
TEENS EXPECTED. THE COLD FRONT IS NOT EXPECTED TO IMPACT THE AREA
UNTIL LATE WEDNESDAY NIGHT/EARLY THURSDAY...WELL BEYOND THE CURRENT
TAF PERIOD.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.
KB
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
WEDNESDAY NIGHT...CHC TSRA.
THURSDAY...CHC TSRA.
FRIDAY...VFR.
SATURDAY...SLT CHC TSRA.
SUNDAY...VFR.
MONDAY...VFR.
BMD
&&
.MARINE...
242 AM CDT
SOUTH TO SOUTHWEST WINDS ARE EXPECTED TO REMAIN FRESH OVER LAKE
MICHIGAN THROUGH WEDNESDAY NIGHT WHEN A COLD FINALLY BEGINS TO
SLIDE SOUTH ACROSS THE LAKE. WINDS WILL GENERALLY BE IN THE 15 TO
25 KT RANGE UNTIL THEN OVER THE NORTH HALF OF THE LAKE...AND UP TO
20 KTS AT TIMES FOR THE SOUTH HALF OF THE LAKE. OUTSIDE OF AN
INITIAL PERIOD OF GUSTY NORTHERLY WINDS BEHIND THE FRONT...WINDS
ARE EXPECTED TO SUBSIDE AS HIGH PRESSURE BUILDS OVER THE AREA
THURSDAY NIGHT AND FRIDAY. WINDS ARE EXPECTED TO TURN SOUTH TO
SOUTHWEST AGAIN NEXT WEEKEND...AND INCREASE ESPECIALLY OVER THE
NORTH HALF OF THE LAKE AHEAD OF ANOTHER COLD FRONT.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion
National Weather Service Lincoln IL
1026 AM CDT Tue Aug 20 2013
.DISCUSSION...
ISSUED 1026 AM CDT Tue Aug 20 2013
9 AM surface map showed high pressure centered over the mid-
Atlantic coast, with ridging extending west into southern IL and
MO. This put most of central IL in a very light wind regime,
though light return southerly flow on the back side of the ridge had
pushed east to the I-55 corridor. Aloft, water vapor imagery
indicated a cutoff mid-level low circulating over west central IL
and an additional shortwave in western KY. 12Z ILX sounding was
quite dry in the mid levels and high-res models focus better
ascent ahead of the KY shortwave as it drifts northeast this
afternoon. A very isolated shower or storm is possible in the far
southeast this afternoon where RAP soundings show little to no cap in
place, however feel if anything does develop should be confined
farther east into southern IN and have maintained a dry forecast.
Otherwise, mostly sunny skies will dominate the CWA today. Mixing
to around 850MB supports highs of 85-89F.
25
&&
.AVIATION...
ISSUED 600 AM CDT Tue Aug 20 2013
MVFR and local IFR vsbys still possible due to ground fog until
13z...esp at DEC and CMI...otherwise VFR conditions are expected
over the remainder of this forecast period. Weak upper level
disturbance moving acrs the area without much in the way of
weather as the atmosphere, except near gound level, was quite
dry. Forecast soundings continue to indicate sct-bkn cumulus
will develop late this morning with bases of 4500-5000 feet.
Will continue to carry mostly scattered bases today with the
better chances of seeing some bkn cigs at times just east of
I-55. What clouds that do form during peak heating today should
once again quickly dissipate late this afternoon with a mainly
clear sky dominating tonight. The threat for more fog again
late tonight/early Wednesday morning appears to be less than
the past few mornings due to a southerly breeze expected to
hold up just enough to prevent any widespread development so
will leave the mention of fog out of the TAFs tonight. Winds
today will be out of the south at 5 to 10 kts.
Smith
&&
.PREV DISCUSSION...
ISSUED 225 AM CDT Tue Aug 20 2013
Illinois remains on the periphery of high pressure that was
centered near the mid-Atlantic coast early this morning. Have seen
some high clouds rotating around an upper level circulation that
was very evident on water vapor imagery, dropping along the
Mississippi River in far western Illinois.
Primary forecast focus remains on rain chances later this week,
along with extended period of very warm conditions.
SHORT TERM...Today through Thursday...
Upper circulation to continue to carve out a broad trough over
Illinois today, with model guidance showing some potential for a
small closed circulation forming by late tonight before the trough
swings eastward. Currently appears that any rain with this feature
will remain to our east. Temperatures continue a slow but steady
rise and should reach the upper 80s most areas by Wednesday.
Main focus shifts to an upper wave moving across southwest Canada
early this morning. Broad east-west ridging over the southern U.S.
should start to amplify across the Rockies Wednesday night,
allowing the wave to dig more as it sweeps through the Great Lakes
region. The guidance is generally in agreement with the resulting
surface front pushing all the way through the state on Thursday.
Still some question as to whether or not this is overly aggressive
for this time of year, especially the NAM solution as it brings
temps all the way down to the lower 50s by Friday morning behind
the front. Rain-wise, have introduced some slight chance PoPs
after midnight Wednesday night across the northern CWA, and a
broad area of 30% chances east of a Macomb to Lawrenceville line
on Thursday. Have lingered some slights into Thursday night and
Friday, as the ECMWF model shows some hints of the front pushing
back northeast.
LONG TERM...Friday through Monday...
Broad dome of high pressure aloft to cover most of the country
this weekend and early next week. Convective systems traversing
the northern flank of the ridge should stay to our north, with
core of the upper high nearly overhead. After a brief cool down on
Friday, gradual warming will take place through early next week,
with highs near 90 becoming more common. Humidity levels not
expected to get out of hand due to the recent dry conditions, so
heat index values will only be a few degrees warmer than the
observed temperatures.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
948 PM CDT WED AUG 21 2013
.UPDATE...
ISSUED AT 946 PM CDT WED AUG 21 2013
SURFACE AND 850 MB FRONTS TO PUSH THROUGH MUCH OF THE AREA OVER THE
NEXT 24 HRS. MOISTURE POOLING JUST AHEAD OF THESE BOUNDARIES IN
WEST TO EAST FASHION WITH SFC DEWPTS IN THE 70S AND LAYER PWATS
APPROACHING 2 INCHES. MEANWHILE...DISTURBANCE IN MONSOONAL
MOISTURE EMERGING INTO THE PLAINS FROM ROCKIES AND ON AN EASTERLY
COURSE AROUND PERIPHERY OF SOUTHERN PLAINS HEAT DOME. THESE
INGREDIENTS ARE ENCOURAGING FOR RAIN PROSPECTS NEXT 24 HRS. ALSO
ENCOURAGING TO SEE SOME PCPN ALREADY SNEAKING INTO FAR NORTH AND
EAST PORTIONS OF CWA... AND ANTICIPATE MORE DEVELOPMENT OVERNIGHT
ZIPPERING BACK TOWARD NE CONVECTION SLIDING E-THEN S/E THROUGH
THU AM PER CORFIDI VECTORS. WILL HAVE UPDATED GRIDS/ZFP OUT SOON.
&&
.SYNOPSIS...
ISSUED AT 314 PM CDT WED AUG 21 2013
12Z UA ANALYSIS HAS AN 850MB TROF RUNNING FROM WESTERN LAKE SUPERIOR
INTO WYOMING. AHEAD OF THIS TROF 850MB DEW POINTS WERE IN THE MID
TEENS FROM UPPER MICHIGAN INTO EASTERN NEBRASKA. SATELLITE/RADAR
TRENDS THROUGH MID AFTERNOON SHOW VERY LITTLE IN THE WAY OF DIURNAL
CLOUDS ACROSS THE AREA BUT CONVECTION HAS FIRED ALONG THE COLD FRONT
FROM NEAR KFSD INTO WESTERN WISCONSIN.
18Z SFC ANALYSIS HAS A WEAK LOW NEAR KFSD. THE FRONT RAN NORTHEAST
FROM THE LOW INTO WESTERN UPPER MICHIGAN. AROUND THE FRONTAL
BOUNDARY DEW POINTS WERE IN THE LOW 70S WITH 60S ACROSS THE
REMAINDER OF THE MIDWEST.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 314 PM CDT WED AUG 21 2013
THE CONVECTION THAT HAS DEVELOPED THIS AFTERNOON IS IN AN AREA OF
STEEP 850-700MB LAPSE RATES AND IN THE SLIGHTLY BETTER
FORCING/CONVERGENCE ASSOCIATED WITH THE FRONTAL ZONE. THE RAP TRENDS
KEEP MORE STABLE AIR ACROSS THE IMMEDIATE AREA THROUGH LATE
AFTERNOON SO ANY CONVECTION APPROACHING THE AREA WILL DISSIPATE.
THE MCS AND LIFT TOOLS SUGGEST ISOLATED TO POSSIBLY SCATTERED
CONVECTION ENTERING THE HWY 20 CORRIDOR DURING THE EARLY EVENING. BY
MID TO LATE EVENING NEW CONVECTION SHOULD DEVELOP AND BECOME LOOSELY
ORGANIZED FROM HWY 30 ON NORTH. BOUNDARIES FROM THIS CONVECTION
SHOULD ALLOW ISOLATED SHOWERS AND STORMS TO DEVELOP ALONG AND SOUTH
OF I-80 AFTER MIDNIGHT.
ON THURSDAY...LINGERING NOCTURNAL CONVECTION SHOULD BE OVER THE AREA
AS THE FRONT CONTINUES TO SLOWLY MOVE SOUTH THROUGH THE AREA.
DIFFERENTIAL HEATING WILL THEN ALLOW NEW CONVECTION TO DEVELOP
DURING THE LATE MORNING AND AFTERNOON HOURS. AS THE NEXT CANADIAN
HIGH BUILDS INTO THE GREAT LAKES...THE DRIER AIR WILL SLOWLY FORCE
THE CONVECTION SOUTH THURSDAY AFTERNOON WITH IT ONLY OVER THE
SOUTHWEST THIRD OF THE CWFA BY THURSDAY EVENING. ..08..
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 314 PM CDT WED AUG 21 2013
AN UPPER RIDGE OVER THE WESTERN STATES IS PROGGED TO BUILD EAST AND
STRENGTHEN THROUGH THE MIDDLE OF NEXT WEEK...PROLONGING THE DRY
CONDITIONS AND BRINGING LATE SUMMER HEAT TO THE REGION.
ABOUT THE ONLY CHANCE OF RAIN WILL BE THE POTENTIAL FOR SOME
LINGERING SHRA/TSRA OVER THE SOUTHWEST THURSDAY NIGHT NEAR A
DECAYING FRONT OVER MISSOURI. FORCING WILL NOT BE VERY STRONG GIVEN
THE WEAK FLOW NEAR THE FRONTAL ZONE AND WITH THE UPPER RIDGE
BUILDING INTO THE REGION...POPS WERE KEPT IN THE SLIGHT CHANCE
CATEGORY.
THE UPPER RIDGE CONTINUES TO BUILD INTO THE REGION WITH A
594DM-PLUS H5 HIGH CENTERED OVER MO BY SUNDAY NIGHT AND REMAINING
IN PLACE THROUGH THE MIDDLE OF THE WEEK. THE STRONGER MID LEVEL
FLOW WILL BE DIVERTED AROUND THE RIDGE WHICH WILL KEEP THE BETTER
FORCING WELL NORTH OF THE AREA. THE GFS AND 12Z ECMWF SHOW SOME QPF
OVER THE AREA BY NEXT WEDNESDAY OR WEDNESDAY NIGHT ASSOCIATED WITH
A SHORT WAVE AND FRONT MOVING THE THROUGH THE WESTERN GREAT LAKES
AND MISSISSIPPI VALLEY. HOWEVER KEPT POPS OUT OF THE FORECAST FOR
NOW WITH MID LEVEL TEMPS PROGGED TO BE AROUND 12C SUGGESTING THESE
FEATURES WILL BE FIGHTING A CAP.
SUMMERTIME HEAT WILL BE RETURNING TO THE REGION AS H8 TEMPS WARM
INTO THE LOW 20/S BY SUNDAY AND REMAIN THERE THROUGH MID WEEK. THE
BLENDED GUIDANCE WAS WARMING HIGH TEMPERATURES TO AROUND 90 BUT
MIXING DOWN H8 TEMPS EARLY NEXT WEEK YIELDED HIGHS IN THE LOW TO MID
90S. FORECAST HIGHS WERE SKEWED TOWARD THE TEMPS DERIVED FROM MIXING
WHICH SEEM MORE REASONABLE. WITH THESE WARMER TEMPERATURES...AND
DEWPOINTS EXPECTED TO BE NEAR 70...WE WILL PROBABLY SEE HEAT INDICES
CLOSE TO 100 DURING THE HEAT OF THE DAY. AT THIS TIME IT DOESN/T
APPEAR THAT WE WILL BE CLOSE TO ANY RECORD HIGHS...AT LEAST THROUGH
THE 28TH. RECORDS DURING THIS TIME ARE NEAR OR ABOVE 100 AT THE
CLIMATE SITES.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 642 PM CDT WED AUG 21 2013
FRONTAL ZONE EXTENDING FROM CENTRAL WI THROUGH SOUTHERN MN WILL SAG
SLOWLY THROUGH THE AREA NEXT 24 HRS ACCOMPANIED BY SOME SHOWERS
AND STORMS. TRYING TO PIN DOWN TIMING AND TERMINALS AFFECTED IS THE
MAIN CHALLENGE. RIGHT NOW IT APPEARS THE BEST PCPN CHCS RESIDE NORTH
OF I-80 OVRNGT AND THU AM. ANY TSRA WILL LIKELY BE ACCOMPANIED BY
PERIOD OF IFR TO MVFR VSBYS. MAINTAINED VCSH WORDING ALL SITES THU
AFTN WITH MID LEVEL BOUNDARY AND MOISTURE AXIS POSITIONED OVER THE
AREA.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...05
SYNOPSIS...08
SHORT TERM...08
LONG TERM...DLF
AVIATION...05
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
659 PM CDT WED AUG 21 2013
.SYNOPSIS...
ISSUED AT 314 PM CDT WED AUG 21 2013
12Z UA ANALYSIS HAS AN 850MB TROF RUNNING FROM WESTERN LAKE SUPERIOR
INTO WYOMING. AHEAD OF THIS TROF 850MB DEW POINTS WERE IN THE MID
TEENS FROM UPPER MICHIGAN INTO EASTERN NEBRASKA. SATELLITE/RADAR
TRENDS THROUGH MID AFTERNOON SHOW VERY LITTLE IN THE WAY OF DIURNAL
CLOUDS ACROSS THE AREA BUT CONVECTION HAS FIRED ALONG THE COLD FRONT
FROM NEAR KFSD INTO WESTERN WISCONSIN.
18Z SFC ANALYSIS HAS A WEAK LOW NEAR KFSD. THE FRONT RAN NORTHEAST
FROM THE LOW INTO WESTERN UPPER MICHIGAN. AROUND THE FRONTAL
BOUNDARY DEW POINTS WERE IN THE LOW 70S WITH 60S ACROSS THE
REMAINDER OF THE MIDWEST.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 314 PM CDT WED AUG 21 2013
THE CONVECTION THAT HAS DEVELOPED THIS AFTERNOON IS IN AN AREA OF
STEEP 850-700MB LAPSE RATES AND IN THE SLIGHTLY BETTER
FORCING/CONVERGENCE ASSOCIATED WITH THE FRONTAL ZONE. THE RAP TRENDS
KEEP MORE STABLE AIR ACROSS THE IMMEDIATE AREA THROUGH LATE
AFTERNOON SO ANY CONVECTION APPROACHING THE AREA WILL DISSIPATE.
THE MCS AND LIFT TOOLS SUGGEST ISOLATED TO POSSIBLY SCATTERED
CONVECTION ENTERING THE HWY 20 CORRIDOR DURING THE EARLY EVENING. BY
MID TO LATE EVENING NEW CONVECTION SHOULD DEVELOP AND BECOME LOOSELY
ORGANIZED FROM HWY 30 ON NORTH. BOUNDARIES FROM THIS CONVECTION
SHOULD ALLOW ISOLATED SHOWERS AND STORMS TO DEVELOP ALONG AND SOUTH
OF I-80 AFTER MIDNIGHT.
ON THURSDAY...LINGERING NOCTURNAL CONVECTION SHOULD BE OVER THE AREA
AS THE FRONT CONTINUES TO SLOWLY MOVE SOUTH THROUGH THE AREA.
DIFFERENTIAL HEATING WILL THEN ALLOW NEW CONVECTION TO DEVELOP
DURING THE LATE MORNING AND AFTERNOON HOURS. AS THE NEXT CANADIAN
HIGH BUILDS INTO THE GREAT LAKES...THE DRIER AIR WILL SLOWLY FORCE
THE CONVECTION SOUTH THURSDAY AFTERNOON WITH IT ONLY OVER THE
SOUTHWEST THIRD OF THE CWFA BY THURSDAY EVENING. ..08..
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 314 PM CDT WED AUG 21 2013
AN UPPER RIDGE OVER THE WESTERN STATES IS PROGGED TO BUILD EAST AND
STRENGTHEN THROUGH THE MIDDLE OF NEXT WEEK...PROLONGING THE DRY
CONDITIONS AND BRINGING LATE SUMMER HEAT TO THE REGION.
ABOUT THE ONLY CHANCE OF RAIN WILL BE THE POTENTIAL FOR SOME
LINGERING SHRA/TSRA OVER THE SOUTHWEST THURSDAY NIGHT NEAR A
DECAYING FRONT OVER MISSOURI. FORCING WILL NOT BE VERY STRONG GIVEN
THE WEAK FLOW NEAR THE FRONTAL ZONE AND WITH THE UPPER RIDGE
BUILDING INTO THE REGION...POPS WERE KEPT IN THE SLIGHT CHANCE
CATEGORY.
THE UPPER RIDGE CONTINUES TO BUILD INTO THE REGION WITH A
594DM-PLUS H5 HIGH CENTERED OVER MO BY SUNDAY NIGHT AND REMAINING
IN PLACE THROUGH THE MIDDLE OF THE WEEK. THE STRONGER MID LEVEL
FLOW WILL BE DIVERTED AROUND THE RIDGE WHICH WILL KEEP THE BETTER
FORCING WELL NORTH OF THE AREA. THE GFS AND 12Z ECMWF SHOW SOME QPF
OVER THE AREA BY NEXT WEDNESDAY OR WEDNESDAY NIGHT ASSOCIATED WITH
A SHORT WAVE AND FRONT MOVING THE THROUGH THE WESTERN GREAT LAKES
AND MISSISSIPPI VALLEY. HOWEVER KEPT POPS OUT OF THE FORECAST FOR
NOW WITH MID LEVEL TEMPS PROGGED TO BE AROUND 12C SUGGESTING THESE
FEATURES WILL BE FIGHTING A CAP.
SUMMERTIME HEAT WILL BE RETURNING TO THE REGION AS H8 TEMPS WARM
INTO THE LOW 20/S BY SUNDAY AND REMAIN THERE THROUGH MID WEEK. THE
BLENDED GUIDANCE WAS WARMING HIGH TEMPERATURES TO AROUND 90 BUT
MIXING DOWN H8 TEMPS EARLY NEXT WEEK YIELDED HIGHS IN THE LOW TO MID
90S. FORECAST HIGHS WERE SKEWED TOWARD THE TEMPS DERIVED FROM MIXING
WHICH SEEM MORE REASONABLE. WITH THESE WARMER TEMPERATURES...AND
DEWPOINTS EXPECTED TO BE NEAR 70...WE WILL PROBABLY SEE HEAT INDICES
CLOSE TO 100 DURING THE HEAT OF THE DAY. AT THIS TIME IT DOESN/T
APPEAR THAT WE WILL BE CLOSE TO ANY RECORD HIGHS...AT LEAST THROUGH
THE 28TH. RECORDS DURING THIS TIME ARE NEAR OR ABOVE 100 AT THE
CLIMATE SITES.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 642 PM CDT WED AUG 21 2013
FRONTAL ZONE EXTENDING FROM CENTRAL WI THROUGH SOUTHERN MN WILL SAG
SLOWLY THROUGH THE AREA NEXT 24 HRS ACCOMPANIED BY SOME SHOWERS
AND STORMS. TRYING TO PIN DOWN TIMING AND TERMINALS AFFECTED IS THE
MAIN CHALLENGE. RIGHT NOW IT APPEARS THE BEST PCPN CHCS RESIDE NORTH
OF I-80 OVRNGT AND THU AM. ANY TSRA WILL LIKELY BE ACCOMPANIED BY
PERIOD OF IFR TO MVFR VSBYS. MAINTAINED VCSH WORDING ALL SITES THU
AFTN WITH MID LEVEL BOUNDARY AND MOISTURE AXIS POSITIONED OVER THE
AREA.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...08
SHORT TERM...08
LONG TERM...DLF
AVIATION...05
AREA FORECAST DISCUSSION
NWS GOODLAND KS
241 AM MDT TUE AUG 20 2013
.SHORT TERM...(TONIGHT THROUGH TUESDAY AFTERNOON)
ISSUED AT 203 PM MDT MON AUG 19 2013
AS OF 3 PM CDT...2 PM MDT...SKIES ACROSS THE TRI-STATE AREA WERE
CLEAR. TEMPERATURES HAVE RESPONDED NICELY WITH THE LACK OF CLOUD
COVER AND RANGED FROM THE MID 80S TO LOW 90S. WINDS WERE FROM THE
SOUTHEAST AT 10 TO 15 MPH WITH GUSTS TO 20 MPH. THE RIDGE OF HIGH
PRESSURE OVER THE SOUTHWEST HAS STRENGTHENED SOME TODAY. SUBSIDENCE
ALOFT WAS ENTRENCHED OVER THE REGION AT THIS TIME.
FOR THE REST OF TODAY AND TONIGHT...WITH THE INFLUENCE OF THE RIDGE
AND SUBSIDENCE ALOFT FIRMLY IN PLACE...PRECIPITATION CHANCES WILL BE
NEAR ZERO. THE HRRR KEEPS SUGGESTING A ISOLATED SHOWER OR STORM IS
POSSIBLE OVER CHEYENNE COUNTY COLORADO BUT NO OTHER MODEL IS
PRODUCING PRECIPITATION OVER THE FORECAST AREA. TEMPERATURES FOR
TONIGHT ARE EXPECTED TO FALL INTO THE LOW 60S UNDER MOSTLY CLEAR
SKIES. LIGHT WINDS AND SOME LINGERING LOW LEVEL MOISTURE MAY ALLOW
FOR SOME PATCHY LIGHT FOG TO FORM...MAINLY ACROSS SOUTHWEST
NEBRASKA. DID NOT THINK THIS WAS WORTHY OF A MENTION IN THE GRIDS AS
VISIBILITIES SHOULD NOT FALL LOWER THAN 4 MILES AT WORSE.
FOR TOMORROW...THE RIDGE OF HIGH PRESSURE WILL STRENGTHEN SLIGHTLY
AGAIN. MODELS PROJECT THAT 850 MB TEMPERATURES WILL WARM A DEGREE OR
TWO OVER TODAYS 850 TEMPS SO A SIMILAR RESPONSE IS EXPECTED IN
SURFACE TEMPERATURES. AS A RESULT...HIGH TEMPERATURES IN THE MID TO
UPPER 90S ARE FORECAST UNDER CLEAR SKIES. SOUTH TO SOUTHEAST WINDS
WILL CONTINUE AS A LEE TROUGH TO THE WEST WILL CONTINUE TO INFLUENCE
THE LOW LEVEL FLOW. BASED ON THE UPPER LEVEL PATTERN AND THE LACK OF
A STRONG DISTURBANCE...PRECIPITATION IS NOT FORECAST FOR TOMORROW.
.LONG TERM...(FRIDAY THROUGH MONDAY)
ISSUED AT 241 AM MDT TUE AUG 20 2013
BROAD UPPER-LEVEL RIDGE DOMINATES THE WX PATTERN THIS WEEKEND AND
INTO EARLY NEXT WEEK. OVER NORTH AMERICA AT THE SYNOPTIC SCALE THIS
RIDGE WILL BE OVER THE CENTRAL PLAINS ON FRIDAY...GRADUALLY BUILDING
TO BECOME AN UPPER-HIGH CENTERED OVER MISSOURI BY EARLY NEXT WEEK.
H5 SOUTH-SOUTHWEST FLOW FROM THIS PATTERN WILL BE UNFAVORABLE FOR
DEVELOPMENT OF STORMS WITH THE NEAREST CHANCE FOR FORCING BEING WHEN
A SHORTWAVE TROUGH MOVES NORTH OVER COLORADO SATURDAY...WHICH ONLY
YUMA COUNTY WOULD HAVE A SHOT AT FOR STORMS SAT NIGHT AT BEST.
SINCE THE THREAT FOR PRECIP VERY LOW OVER THE EXTENDED PERIOD THE
PRIMARY FORECAST CONCERNS WERE MAX/MIN TEMPS AND WINDS. GUIDANCE WAS
PARTICULARLY SOLID FOR TEMPS WITH GFS/ECMWF AND THEIR ENSEMBLES
GIVING SIMILAR RANGES IN THE LOW TO MID 90S THROUGH THE PERIOD...A
BIT ABOVE NORMAL FOR LATE AUGUST BUT NOT UNCOMMON AT ALL. WINDS WILL
BE LIGHT TO BREEZY OUT OF THE SOUTH...WITH A VERY NICE HIGH PLAINS
NOCTURNAL LOW-LEVEL JET EACH NIGHT WITH A 35-45KT MAXIMA AT 850MB.
UNFORTUNATELY THIS LLJ WILL NOT MEAN MUCH FOR THE WEATHER PATTERN
WITH NO STORMS AVAILABLE TO TAKE ADVANTAGE OF IT...WITH SURFACE
WINDS KEEPING UP OR EVEN INCREASING IN THE OVERNIGHT PERIODS BEING
THE MAIN EFFECT OF THIS PHENOMENON.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1059 PM MDT MON AUG 19 2013
VFR TO IFR CONDITIONS FORECAST FOR THE 6Z TAFS. PREVIOUS TAFS LOOK
VERY REASONABLE. AS SUCH MADE ONLY A FEW MODIFICATIONS. BASED ON
YESTERDAY/S OBS AND THE CURRENT DEW POINTS COMPARED TO YESTERDAY/S
EARLY MORNING OBS...AM THINKING FOG IS VERY LIKELY AROUND 12Z.
DEW POINTS ARE ACTUALLY A FEW DEGREES HIGHER NOW THAN WHEN FOG
FORMED YESTERDAY MORNING...AND THERE IS NO REASON THE DEW POINTS
WILL FALL DURING THE NIGHT. WITH A DEEP DRY LAYER ABOVE THE SHALLOW
SATURATION AT THE SURFACE...DO NOT BELIEVE THE FOG WILL LAST VERY
LONG AND SHOULD BE VERY SHORT- LIVED. OTHERWISE WINDS WILL BECOME
BREEZY DURING THE AFTERNOON THEN BECOME LIGHT BY THE EARLY
EVENING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...RRH
LONG TERM...JJM
AVIATION...JTL
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1120 PM MDT MON AUG 19 2013
.SHORT TERM...(TONIGHT THROUGH TUESDAY AFTERNOON)
ISSUED AT 203 PM MDT MON AUG 19 2013
AS OF 3 PM CDT...2 PM MDT...SKIES ACROSS THE TRI-STATE AREA WERE
CLEAR. TEMPERATURES HAVE RESPONDED NICELY WITH THE LACK OF CLOUD
COVER AND RANGED FROM THE MID 80S TO LOW 90S. WINDS WERE FROM THE
SOUTHEAST AT 10 TO 15 MPH WITH GUSTS TO 20 MPH. THE RIDGE OF HIGH
PRESSURE OVER THE SOUTHWEST HAS STRENGTHENED SOME TODAY. SUBSIDENCE
ALOFT WAS ENTRENCHED OVER THE REGION AT THIS TIME.
FOR THE REST OF TODAY AND TONIGHT...WITH THE INFLUENCE OF THE RIDGE
AND SUBSIDENCE ALOFT FIRMLY IN PLACE...PRECIPITATION CHANCES WILL BE
NEAR ZERO. THE HRRR KEEPS SUGGESTING A ISOLATED SHOWER OR STORM IS
POSSIBLE OVER CHEYENNE COUNTY COLORADO BUT NO OTHER MODEL IS
PRODUCING PRECIPITATION OVER THE FORECAST AREA. TEMPERATURES FOR
TONIGHT ARE EXPECTED TO FALL INTO THE LOW 60S UNDER MOSTLY CLEAR
SKIES. LIGHT WINDS AND SOME LINGERING LOW LEVEL MOISTURE MAY ALLOW
FOR SOME PATCHY LIGHT FOG TO FORM...MAINLY ACROSS SOUTHWEST
NEBRASKA. DID NOT THINK THIS WAS WORTHY OF A MENTION IN THE GRIDS AS
VISIBILITIES SHOULD NOT FALL LOWER THAN 4 MILES AT WORSE.
FOR TOMORROW...THE RIDGE OF HIGH PRESSURE WILL STRENGTHEN SLIGHTLY
AGAIN. MODELS PROJECT THAT 850 MB TEMPERATURES WILL WARM A DEGREE OR
TWO OVER TODAYS 850 TEMPS SO A SIMILAR RESPONSE IS EXPECTED IN
SURFACE TEMPERATURES. AS A RESULT...HIGH TEMPERATURES IN THE MID TO
UPPER 90S ARE FORECAST UNDER CLEAR SKIES. SOUTH TO SOUTHEAST WINDS
WILL CONTINUE AS A LEE TROUGH TO THE WEST WILL CONTINUE TO INFLUENCE
THE LOW LEVEL FLOW. BASED ON THE UPPER LEVEL PATTERN AND THE LACK OF
A STRONG DISTURBANCE...PRECIPITATION IS NOT FORECAST FOR TOMORROW.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 203 PM MDT MON AUG 19 2013
THE UPPER HIGH CURRENTLY OVER COLORADO/ARIZONA IS FORECAST TO
MOVE EAST TO KANSAS/OKLAHOMA BY THE END OF THE WEEK AND
ULTIMATELY WIND UP OVER ILLINOIS BY THE END OF THE PERIOD. THIS
WILL BE THE PRIMARY FEATURE AFFECTING THE WEATHER...AND IN GENERAL
THIS WILL TRANSLATE INTO A WARM AND DRY PERIOD FOR THE FORECAST
AREA.
ONE POSSIBLE CAVEAT TO THE DRY SCENARIO MENTIONED ABOVE WILL BE A
WEAK SHORT WAVE TROUGH FORECAST BY THE NAM AND GFS TO RIDE OVER
THE TOP OF THE RIDGE WEDNESDAY NIGHT. BOTH MODELS INDICATE A
CHANCE FOR SCATTERED CONVECTION WED NIGHT WHILE THE ECMWF KEEPS
THINGS DRY AND THE GEM SHOWS CONVECTION JUST NORTH OF THE AREA.
FOR NOW HAVE KEPT PREVIOUS FORECAST OF LOW CHANCE POPS DURING THIS
TIME WITH AN EMPHASIS ON THE NORTHWEST AND CENTRAL COUNTIES.
TEMPERATURES WILL BE ABOVE NORMAL IN THE LOW-MID 90S FOR MUCH OF
THE PERIOD WHICH IS 5-8 DEGREES ABOVE NORMAL...WHILE LOWS REMAIN
GENERALLY IN THE 60S.
AT THE END OF THE PERIOD AND INTO THE MIDDLE OF NEXT WEEK WHEN THE
UPPER HIGH HAS SHIFTED EAST...THERE WILL BE AN INCREASING WINDOW
OF OPPORTUNITY FOR SCATTERED CONVECTION AS THE AREA COMES UNDER
MORE OF A WEAK SOUTHWEST FLOW ALOFT. UNTIL THEN...PRECIP CHANCES
LOOK MEAGER.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1059 PM MDT MON AUG 19 2013
VFR TO IFR CONDITIONS FORECAST FOR THE 6Z TAFS. PREVIOUS TAFS LOOK
VERY REASONABLE. AS SUCH MADE ONLY A FEW MODIFICATIONS. BASED ON
YESTERDAY/S OBS AND THE CURRENT DEW POINTS COMPARED TO YESTERDAY/S
EARLY MORNING OBS...AM THINKING FOG IS VERY LIKELY AROUND 12Z.
DEW POINTS ARE ACTUALLY A FEW DEGREES HIGHER NOW THAN WHEN FOG
FORMED YESTERDAY MORNING...AND THERE IS NO REASON THE DEW POINTS
WILL FALL DURING THE NIGHT. WITH A DEEP DRY LAYER ABOVE THE SHALLOW
SATURATION AT THE SURFACE...DO NOT BELIEVE THE FOG WILL LAST VERY
LONG AND SHOULD BE VERY SHORT- LIVED. OTHERWISE WINDS WILL BECOME
BREEZY DURING THE AFTERNOON THEN BECOME LIGHT BY THE EARLY
EVENING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...RRH
LONG TERM...DLF
AVIATION...JTL
AREA FORECAST DISCUSSION
NWS CARIBOU ME
604 AM EDT TUE AUG 20 2013
.SYNOPSIS...
A WEAK FRONTAL BOUNDARY WILL PUSH INTO NORTHERN AREAS TODAY. THE
FRONT WILL LIFT BACK NORTH TONIGHT INTO WEDNESDAY AS HIGH
PRESSURE MOVES ONTO THE MID ATLANTIC COAST.
&&
.NEAR TERM /THROUGH TONIGHT/...
604 AM UPDATE...MADE SOME ADJUSTMENTS TO THE POP/WX/QPF GRIDS FOR
EARLY THIS MORNING BASED ON THE LATEST RADAR TRENDS AND
OBSERVATIONS. SCATTERED SHOWERS ARE MOVING ACROSS CENTRAL AND
SOUTHERN PISCATAQUIS COUNTY...FURTHER SOUTH THEN EARLIER EXPECTED.
THE HRRR DID NOT DO A GOOD JOB WITH THE SOUTHERN EXTENT OF THE
SHOWERS EARLY THIS MORNING. THE GFS AND RUC HAD A SOMEWHAT BETTER
HANDLE ON THE SHOWERS. SHOWERS ACROSS AROOSTOOK COUNTY HAVE PUT
DOWN A FEW HUNDREDTHS TO AROUND ONE TENTH OF AN INCH OF RAIN
DURING THE PAST FEW HOURS. EXPECT MUCH OF THE SHOWER ACTIVITY TO
PUSH OUT OF THE CWA BY MID MORNING WITH A BIT OF A BREAK BEFORE
MORE SHOWERS AND STORMS FIRE UP THIS AFTERNOON.
A WEAK BACKDOOR COLD FRONT IS SLIPPING SOUTH INTO NORTHERN MAINE
EARLY THIS MORNING IN RESPONSE TO AN AREA OF LOW PRESSURE THAT
TRACKED ACROSS THE NW ATLANTIC AND IS NOW NEAR THE SOUTHERN TIP OF
GREENLAND. THE FRONT ALTHOUGH WEAK WILL PROVIDE SOME CONVERGENCE
AND A FOCUSING MECHANISM FOR CONVECTION TODAY INTO THIS EVENING.
OVERALL THE ATMOSPHERIC CONDITIONS LOOK MORE FAVORABLE FOR
CONVECTION TODAY WHEN COMPARED TO YESTERDAY. THE PRECIPITABLE H20
WHICH WAS 1.05 INCHES ON THE 00Z KCAR SOUNDING IS EXPECTED TO
INCREASE TO AROUND 1.3 INCHES AND SFC DEW POINTS WHICH WERE IN THE
50S MONDAY AFTERNOON WILL LIKELY CLIMB INTO THE LOW 60S TODAY. THE
SBCAPE IS PROGGED AT 500-1000 J/KG ON THE NAM...AND MUCH HIGHER ON
THE GFS WHICH LOOKS OVERDONE. BOTH THE NAM AND GFS HAVE THE 0-6 KM
SHEAR AROUND 35 KT THIS AFTERNOON SO SOME OF THE STORMS MAY BECOME
ORGANIZED ENOUGH TO PRODUCE GUSTY WIND AND HEAVY DOWNPOURS AND AN
ISOLATED STORM COULD BECOME SEVERE. THE MOST LIKELY AREAS FOR
STORMS WILL BE ACROSS NORTHERN MAINE FROM THE KATAHDIN REGION
NORTH AND ACROSS EASTERN MAINE ABOUT AS FAR SOUTH AS NORTHERN
WASHINGTON COUNTY. THE WARMEST TEMPS TODAY WILL BE ACROSS INTERIOR
DOWNEAST AREAS WHERE THERE WILL BE MORE SUNSHINE AND A MUCH LOWER
CHANCE OF CONVECTION. HIGHS WILL LIKELY REACH THE MID 80S IN THE
BANGOR AREA AND NOT GET OUT OF THE 70S FROM THE KATAHDIN REGION
NORTH. THE CONVECTION SHOULD DIE OFF FAIRLY QUICKLY THIS EVENING
WITH THE LOSS OF DAYTIME HEATING AS THE ATMOSPHERE RAPIDLY
STABILIZES. LOWS TONIGHT WILL BE FAIRLY UNIFORM ACROSS THE REGION
FROM THE UPPER 50S TO LOW 60S AND A BIT ON THE MUGGY SIDE TOO.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BE BUILDING OFF THE MID ATLANTIC COAST ON
WEDNESDAY AS A FRONTAL BOUNDARY PUSHES SOUTH INTO EASTERN CANADA.
THE COMBINATION OF THE HIGH TO THE SOUTH AND FRONT TO THE NORTH
WILL BRING A VERY WARM AND BREEZY DAY ON WEDNESDAY WITH A PARTLY
TO MOSTLY SUNNY SKY. THE GRADIENT WILL ALLOW A BREEZE TO CONTINUE
OVERNIGHT MAINLY ACROSS THE NORTH. THIS MAY RESULT IN WARMER LOWS
NORTH THAN DOWNEAST. LOWS THROUGHOUT THE REGION SHOULD BE IN THE
LOW 60S. WARM AND HUMID CONDITIONS WILL CONTINUE THURSDAY. A
STRONG FRONTAL BOUNDARY WILL PUSH DOWN INTO THE AREA LATE THURSDAY
WITH SHOWERS AND THUNDERSTORMS LIKELY ESPECIALLY IN NORTHERN AND
WESTERN AREAS LATE IN THE DAY.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A STRONG COLD FRONT WILL PUSH ACROSS THE AREA THURSDAY NIGHT. THIS
WILL GIVE WAY TO A PARTLY SUNNY AND LESS HUMID DAY ON FRIDAY AS A
WEAK UPPER LEVEL TROUGH FOLLOWS THE FRONT. A LARGE AREA OF HIGH
PRESSURE WILL THEN BUILD INTO THE REGION OVER THE WEEKEND BRINGING
SUNNY AND DRY DAYS BOTH SATURDAY AND SUNDAY. HIGH PRESSURE WILL
BRING A SUNNY START TO MONDAY. WARM ADVECTION BEHIND THE HIGH AND
AHEAD OF A TROUGH OF LOW PRESSURE DIPPING DOWN FROM THE NORTHWEST
WILL THEN BRING SOME INCREASING CLOUDS MONDAY AFTERNOON. THIS WILL
BE FOLLOWED BY A CHANCE FOR A SHOWER OR THUNDERSTORM LATE IN THE
DAY ESPECIALLY IN WESTERN AREAS AS THE FRONT PUSHES IN.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
NEAR TERM: VFR THROUGH TONIGHT...EXCEPT MVFR WITH VERY BRIEF IFR
IN HEAVIER SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING
AT THE NORTHERN TERMINALS.
SHORT TERM: VFR CONDITIONS ARE EXPECTED WEDNESDAY INTO EARLY
THURSDAY. CONDITIONS MAY LOWER TO MVFR OR IFR IN SHOWERS AND
THUNDERSTORMS LATE THURSDAY OR THURSDAY EVENING. VFR CONDITIONS
WILL RETURN FRIDAY AND CONTINUE THROUGH THE WEEKEND.
&&
.MARINE...
NEAR TERM: THE SEAS ARE RUNNING AROUND 2-3 FT ON THE COASTAL WATERS
AND AROUND 1 FT ON THE INTRA-COASTAL WATERS. LITTLE CHANGE IS
EXPECTED IN THE SEA STATE THROUGH TONIGHT WITH BOTH THE WIND AND
SEAS REMAINING WELL BELOW SCA LEVELS.
SHORT TERM: WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SCA
WEDNESDAY THROUGH THE COMING WEEKEND.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...CB
SHORT TERM...BLOOMER
LONG TERM...BLOOMER
AVIATION...CB/BLOOMER
MARINE...CB/BLOOMER
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
953 PM EDT WED AUG 21 2013
.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL SLIDE EAST INTO THE REGION
TONIGHT AND THURSDAY BEFORE EXITING THURSDAY NIGHT. A STRONG COLD
FRONT WILL SLIDE THROUGH THE REGION ON FRIDAY. HIGH PRESSURE WILL
BUILD IN FROM THE NORTH FRIDAY NIGHT THROUGH THE COMING WEEKEND
WITH DRIER AND COOLER WEATHER.
&&
.NEAR TERM /THROUGH THURSDAY/...
FORECAST UPDATED FOR POPS AND ADDING PATCHY FOG. GENERAL IDEA WAS
TO DECREASE POPS FOR THE OVRNGT HRS (BASED ON RADAR TRENDS AND
LATEST MODEL GUIDANCE).
PREVIOUS DISCUSSION...
WATER VAPOR IMAGERY SHOWS A STRONG UPPER LOW OVER THE OHIO VALLEY
WITH JET ENERGY NOW BEGINNING TO MOVE UNDER AND UP THE EASTERN
SIDE OF THE TROUGH. THE 12Z NAM SHOWS THAT THE JET AT 300 MB IS
AROUND 6O KTS. THIS JET WILL HELP TO PULL THE TROUGH EASTWARD THIS
EVENING WHILE ALSO HELPING TO AID IN THE CONVECTION THAT HAS BEEN
FIRING OVER THE HIGHER TERRAIN WEST OF THE AREA. AS THIS FEATURE
PULLS EAST...EXPECT THAT THE CONVECTION OVER THE NC PIEDMONT AND
BEGINNING TO DEVELOP OVER THE VA PIEDMONT WILL PULL EAST INTO
EASTERN VIRGINIA AND EVENTUALLY LIFT NE INTO THE LOWER MD EASTERN
SHORE. HAVE BEEN A LITTLE AGGRESSIVE WITH POPS THIS AFTERNOON
SHOWING AN AREA OF LIKELY POPS NEAR PTB/RIC. THESE POPS MAY BE A
TOUCH HIGH...BUT WITH RADAR SHOWING LOTS OF CONVECTION NOT FAR
AWAY AND THE UPPER LOW BEGINNING TO MOVE WILL KEEP THE 60 POPS IN
FOR NOW. AFTER 6Z...THE JET ENERGY AND SHORTWAVE ENERGY WILL BE
NORTH AND EAST OF THE AREA...AND SHOULD BEGIN TO FEEL THE
INFLUENCE OF THE DRY AIR...SHOWING UP ON THE WATER VAPOR NOW OVER
TN. THIS SHOULD HELP TO SHUT DOWN THE CONVECTION SO HAVE TAPERED
POPS OVERNIGHT. FOR LOWS OVERNIGHT...WITH THE SFC NOT CHANGING AIR
MASS AND LOT OF CLOUDS WITH GOOD MOISTURE HAVE LEANED TOWARD THE
WARMER NUMBERS...TRYING TO GET NEAR OR JUST ABOVE LAST NIGHT LOWS.
ON THURSDAY...THE UPPER TROUGH WILL BE OVER THE AREA AND SLIDING
EAST. THE 12Z NAM AND GFS BOTH SHOW MORE SHORTWAVE ENERGY DIVING
DOWN THE BACK SIDE OF THE TROUGH WITH A VERY MOIST LOW LEVEL AIR
MASS STILL IN PLACE...SCATTERED CONVECTION IS STILL POSSIBLE SO
HAVE HELD ON TO SOME AFTERNOON POPS AS THE TROUGH EXITS. FOR
HIGHS...THE GFS HAS BEEN MUCH BETTER TODAY AND THE NAM SEEMS TO
COOL THE ATMOSPHERE A LITTLE TO MUCH SO HAVE LEANED TOWARD THE
GFS/MAV NUMBERS GETTING HIGHS INTO THE U80S-NR 90 DEGREES.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
THE UPPER TROUGH EXITS QUICKLY THURS EVENING...AND THEN A STRONG
COLD FRONT...NOW OVER THE UPPER MIDWEST WILL MOVE THROUGH THE
GREAT LAKES AN INTO THE MID ATLANTIC STATES LATE THURS NIGHT AND
FRIDAY. THE LIFT FIELDS IN THE MODELS ARE NOT ALL THAT IMPRESSIVE
AND THE SFC CONVERGENCE LOOKS A BIT WEAK. BUT WITH THE AMOUNT OF
MOISTURE AROUND...HAVE HELD ON TO SOME LOW CHANCE POPS ALONG THE
FRONT. THE MODELS HAVE SLOWED A TOUCH WITH THE SPEED FOCUSING MORE
OF THE FRONT ON FRIDAY...BUT THEY DO CONTINUE TO PUSH THE FRONT
WELL SOUTH OF THE AREA BY SATURDAY. NORMALLY THE MODELS ARE A BIT
BULLISH THIS TIME OF YR WITH THE FRONTS...BUT THERE IS A VERY
STRONG AREA OF HIGH PRESSURE...ABOUT 1026 MB IN THE NAM...WHICH
SUPPORTS GETTING THE FRONT COMPLETELY SOUTH OF THE AREA. THIS WILL
BRING AN END TO THE SHOWER CHANCES ON FRI NIGHT AND ALLOW FOR A
MUCH COOLER AND DRIER AIR MASS FOR SATURDAY.
FOR TEMPERATURES HAVE LEANED TOWARD THE MAV NUMBERS A LITTLE MORE
ON FRIDAY BASED UPON CURRENT TRENDS AND THE FACT THAT THE AIR MASS
REALLY DOES NOT CHANGE UNTIL THE COLD FRONT PASSES ON FRI EVENING.
BY SATURDAY...WITH DRIER AIR AND COOLER AIR ALOFT SHOULD SEE
COOLER HIGHS IN THE LOW TO MID 80S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
VERY LITTLE CHANGE TO EXTENDED PORTION OF THE FORECAST. A
LARGE-SCALE AREA OF HIGH PRESSURE SETTLES INTO THE MID ATLANTIC
STATES THROUGH THE WEEKEND AND ORIGINATES FROM THE HUDSON BAY AREA
OF CANADA. THIS WILL BRING A MUCH COOLER AND DRIER AIR MASS TO THE
REGION DURING THIS TIME. EXPECT A GRADUAL COOLING TREND THROUGH
SUNDAY NIGHT WITH HIGHS IN THE LOWER 80S (MID TO UPPER 70S IMMEDIATE
COAST) AND LOWS IN THE LOW TO MID 60S (POSSIBLY UPPER 50S IN THE
EASTERN PIEDMONT). CONDITIONS BEGIN TO REBOUND SLIGHTLY ON MONDAY AS
HIGH PRESSURE SHIFTS SOUTHEAST OFF THE CAROLINA COAST. ON
TUESDAY...A LEE TROUGH DEVELOPS AND A BACKDOOR FRONT PASSES OVER NE
COUNTIES (ESPECIALLY THE MD/VA EASTERN SHORE). THE BACKDOOR FRONT
SHOULD ACT AS A CATALYST FOR LONGWAVE TROUGHING TO COMMENCE OVER THE
NE CONUS DURING THE SECOND HALF OF NEXT WEEK. IF THIS TREND
CONTINUES...THEN ANTICIPATE A RETURN TO WARMER TEMPS BUT SHOWERY
CONDITIONS WITH EACH PASSING DAY.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
SCTD SHWRS AND ISOLATED TSTMS CONTINUE OVER THE AREA IN
ASSOCIATION WITH A WEAK UPR TROF MOVING ACROSS THE AREA. HAVE
ATTEMPTED TO USE CURRENT RADAR TO TIME/PLACE ANY PRECIP IN TAFS
THROUGH 03Z. TROF MOVES ACROSS REGION THROUGH 12Z...WITH CHANCES
FOR SHWRS AND ISOLATED TSTMS PERSISTING. HAVE INCLUDED VCSH IN
TAFS BASED UPON THE TIMING SHOWN ON 18Z NAM. PRECIP SHOULD CLEAR
TERMINALS BY 13Z...LEAVING VFR CONDITIONS. THERE MAY BE SOME
ADDITIONAL SHWR/TSTM ACTIVITY THURSDAY AFTERNOON...BUT HAVE LEFT
OUT OF 00Z TAFS PRIMARILY DUE TO TIMING UNCERTAINTY. HAVE ALSO
INSERTED SOME FOG INTO THE KSBY TAF...BASED UPON PERSISTENCE AND
THE POTENTIAL FOR LESS CLOUDS THAN NAM TSECTIONS SUGGEST.
HOWEVER...HAVE NOT BROUGHT CONDITIONS TO LIFR AS OCCURRED LAST
NIGHT.
SCTD SHOWERS/TSTMS WILL REMAIN POSSIBLE THRU EARLY FRI...BEFORE A
COLD FRONT SWEEPS THRU HIGH PRESSURE WILL BUILD IN BEHIND THE
FRONT FOR FRI NGT THRU THE WEEKEND.
&&
.MARINE...
7 PM UPDATE...HAVE MADE SOME UPWARD ADJUSTMENTS TO WINDS/WAVES ON
THE CHESAPEAKE BAY...ESPECIALLY WESTERN SIDE...BASED UPON CURRENT
CONDITIONS AND LATEST HIGH RES MODEL OUTPUT. HRRR SEEMS TO HAVE A
GOOD HANDLE ON VERY SHORT TERM...AND HAVE USED IT AS PRIMARY WIND
GUIDANCE THROUGH 06Z THURSDAY. NO CHGS AFTER 06Z.
AFTERNOON DISCUSSION...LITTLE TO NO CHANGE TO ONGOING MARINE
FORECAST TONIGHT THROUGH MONDAY. WIND DIRECTIONS HAVE RETAINED
MORE OF A SE-S DIRECTION TODAY THAN PREVIOUSLY ANTICIPATED AND
HAVE INCREASED TO AROUND 10 KT. WINDS WILL CONTINUE TO SLOWLY VEER
TO THE S-SW OVERNIGHT AND INCREASE TWD 10-15 KT AS AN APPROACHING
TROUGH FROM THE OHIO VALLEY TIGHTENS THE PRESSURE GRADIENT OVER
THE WATERS. ALSO EXPECT SHOWER AND THUNDERSTORM CHANCES TO
INCREASE OVERNIGHT AS DECENT SHORTWAVE ENERGY/MOISTURE AND A JET
MAX ENHANCE LIFT/RAIN POTENTIAL. SHOWERS LINGER NEAR THE COAST
EARLY THURSDAY MORNING BUT THERE SHOULD BE A BRIEF REPRIEVE DURING
THE MID-LATE MORNING THROUGH EARLY AFTERNOON HOURS BEFORE
THUNDERSTORMS REGENERATE ALONG A COLD FRONT CROSSING THE WATERS
INTO THE EVENING. WINDS WILL BE PRIMARILY FROM THE SW AOB 15 KT ON
THURSDAY...THEN VEER TO THE W BY FRIDAY MORNING. SEAS WILL AVERAGE
2-3 FT AND WAVES ON CHES BAY WILL AVERAGE 1-2 FT.
THE FRONT STALLS ALONG THE CAROLINAS LATE THURSDAY NIGHT INTO AT
LEAST FRIDAY AFTERNOON...PROVIDING ADDITIONAL FOCUS/CHANCES FOR
AFTERNOON SHOWERS/STORMS ON FRIDAY. WINDS WILL START OUT FROM THE W
AND THEN VEER TO THE NW LATE IN THE AFTERNOON AS HIGH PRESSURE FROM
THE GREAT LAKES BEGINS TO SLIDE INTO THE REGION FROM THE NW. SPEEDS
STAY AOB 15 KT. THE FRONT FINALLY GETS PUSHED WELL SOUTH OF THE AREA
FRIDAY NIGHT BY THE LARGE-SCALE HIGH PRESSURE BUILDING INTO THE MID
ATLANTIC STATES THROUGHOUT THE WEEKEND. COOLER AND DRIER AIR WILL
ACCOMPANY THE HIGH AND QUICKLY BRING PRECIPITATION TO AN END FRIDAY
NIGHT. MODEL GUIDANCE WINDS CONTINUE TO KEEP WIND SPEEDS AOB 15 KT
AS THE COOLER AIR MOVES OVER WARMER WATERS FOR FRIDAY NIGHT INTO
SATURDAY. IN FACT...THEY ARE SHOWING AN INCREASE IN WINDS THROUGH
THE DAY ON SATURDAY AS THE COOL AIR FINALLY ARRIVES AND WINDS BECOME
NELY. WILL STILL MONITOR THE POTENTIAL FOR SCA CONDITIONS BUT NONE
ARE ANTICIPATED ATTM. SURFACE HIGH PRESSURE AND NE-E WINDS AOB 15 KT
SETTLE OVER THE WATERS THROUGHOUT THE WEEKEND. HIGH PRESSURE THEN
SLIDES SOUTHEAST OFF THE CAROLINA COAST ON MONDAY...SHIFTING WINDS
FROM E TO SE-S.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ESS
NEAR TERM...ESS/MAS
SHORT TERM...ESS
LONG TERM...BMD
AVIATION...WRS
MARINE...BMD/WRS
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
742 PM EDT WED AUG 21 2013
.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL SLIDE EAST INTO THE REGION
TONIGHT AND THURSDAY BEFORE EXITING THURSDAY NIGHT. A STRONG COLD
FRONT WILL SLIDE THROUGH THE REGION ON FRIDAY. HIGH PRESSURE WILL
BUILD IN FROM THE NORTH FRIDAY NIGHT THROUGH THE COMING WEEKEND
WITH DRIER AND COOLER WEATHER.
&&
.NEAR TERM /THROUGH THURSDAY/...
WATER VAPOR IMAGERY SHOWS A STRONG UPPER LOW OVER THE OHIO VALLEY
WITH JET ENERGY NOW BEGINNING TO MOVE UNDER AND UP THE EASTERN
SIDE OF THE TROUGH. THE 12Z NAM SHOWS THAT THE JET AT 300 MB IS
AROUND 6O KTS. THIS JET WILL HELP TO PULL THE TROUGH EASTWARD THIS
EVENING WHILE ALSO HELPING TO AID IN THE CONVECTION THAT HAS BEEN
FIRING OVER THE HIGHER TERRAIN WEST OF THE AREA. AS THIS FEATURE
PULLS EAST...EXPECT THAT THE CONVECTION OVER THE NC PIEDMONT AND
BEGINNING TO DEVELOP OVER THE VA PIEDMONT WILL PULL EAST INTO
EASTERN VIRGINIA AND EVENTUALLY LIFT NE INTO THE LOWER MD EASTERN
SHORE. HAVE BEEN A LITTLE AGGRESSIVE WITH POPS THIS AFTERNOON
SHOWING AN AREA OF LIKELY POPS NEAR PTB/RIC. THESE POPS MAY BE A
TOUCH HIGH...BUT WITH RADAR SHOWING LOTS OF CONVECTION NOT FAR
AWAY AND THE UPPER LOW BEGINNING TO MOVE WILL KEEP THE 60 POPS IN
FOR NOW. AFTER 6Z...THE JET ENERGY AND SHORTWAVE ENERGY WILL BE
NORTH AND EAST OF THE AREA...AND SHOULD BEGIN TO FEEL THE
INFLUENCE OF THE DRY AIR...SHOWING UP ON THE WATER VAPOR NOW OVER
TN. THIS SHOULD HELP TO SHUT DOWN THE CONVECTION SO HAVE TAPERED
POPS OVERNIGHT. FOR LOWS OVERNIGHT...WITH THE SFC NOT CHANGING AIR
MASS AND LOT OF CLOUDS WITH GOOD MOISTURE HAVE LEANED TOWARD THE
WARMER NUMBERS...TRYING TO GET NEAR OR JUST ABOVE LAST NIGHT LOWS.
ON THURSDAY...THE UPPER TROUGH WILL BE OVER THE AREA AND SLIDING
EAST. THE 12Z NAM AND GFS BOTH SHOW MORE SHORTWAVE ENERGY DIVING
DOWN THE BACK SIDE OF THE TROUGH WITH A VERY MOIST LOW LEVEL AIR
MASS STILL IN PLACE...SCATTERED CONVECTION IS STILL POSSIBLE SO
HAVE HELD ON TO SOME AFTERNOON POPS AS THE TROUGH EXITS. FOR
HIGHS...THE GFS HAS BEEN MUCH BETTER TODAY AND THE NAM SEEMS TO
COOL THE ATMOSPHERE A LITTLE TO MUCH SO HAVE LEANED TOWARD THE
GFS/MAV NUMBERS GETTING HIGHS INTO THE U80S-NR 90 DEGREES.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
THE UPPER TROUGH EXITS QUICKLY THURS EVENING...AND THEN A STRONG
COLD FRONT...NOW OVER THE UPPER MIDWEST WILL MOVE THROUGH THE
GREAT LAKES AN INTO THE MID ATLANTIC STATES LATE THURS NIGHT AND
FRIDAY. THE LIFT FIELDS IN THE MODELS ARE NOT ALL THAT IMPRESSIVE
AND THE SFC CONVERGENCE LOOKS A BIT WEAK. BUT WITH THE AMOUNT OF
MOISTURE AROUND...HAVE HELD ON TO SOME LOW CHANCE POPS ALONG THE
FRONT. THE MODELS HAVE SLOWED A TOUCH WITH THE SPEED FOCUSING MORE
OF THE FRONT ON FRIDAY...BUT THEY DO CONTINUE TO PUSH THE FRONT
WELL SOUTH OF THE AREA BY SATURDAY. NORMALLY THE MODELS ARE A BIT
BULLISH THIS TIME OF YR WITH THE FRONTS...BUT THERE IS A VERY
STRONG AREA OF HIGH PRESSURE...ABOUT 1026 MB IN THE NAM...WHICH
SUPPORTS GETTING THE FRONT COMPLETELY SOUTH OF THE AREA. THIS WILL
BRING AN END TO THE SHOWER CHANCES ON FRI NIGHT AND ALLOW FOR A
MUCH COOLER AND DRIER AIR MASS FOR SATURDAY.
FOR TEMPERATURES HAVE LEANED TOWARD THE MAV NUMBERS A LITTLE MORE
ON FRIDAY BASED UPON CURRENT TRENDS AND THE FACT THAT THE AIR MASS
REALLY DOES NOT CHANGE UNTIL THE COLD FRONT PASSES ON FRI EVENING.
BY SATURDAY...WITH DRIER AIR AND COOLER AIR ALOFT SHOULD SEE
COOLER HIGHS IN THE LOW TO MID 80S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
VERY LITTLE CHANGE TO EXTENDED PORTION OF THE FORECAST. A
LARGE-SCALE AREA OF HIGH PRESSURE SETTLES INTO THE MID ATLANTIC
STATES THROUGH THE WEEKEND AND ORIGINATES FROM THE HUDSON BAY AREA
OF CANADA. THIS WILL BRING A MUCH COOLER AND DRIER AIR MASS TO THE
REGION DURING THIS TIME. EXPECT A GRADUAL COOLING TREND THROUGH
SUNDAY NIGHT WITH HIGHS IN THE LOWER 80S (MID TO UPPER 70S IMMEDIATE
COAST) AND LOWS IN THE LOW TO MID 60S (POSSIBLY UPPER 50S IN THE
EASTERN PIEDMONT). CONDITIONS BEGIN TO REBOUND SLIGHTLY ON MONDAY AS
HIGH PRESSURE SHIFTS SOUTHEAST OFF THE CAROLINA COAST. ON
TUESDAY...A LEE TROUGH DEVELOPS AND A BACKDOOR FRONT PASSES OVER NE
COUNTIES (ESPECIALLY THE MD/VA EASTERN SHORE). THE BACKDOOR FRONT
SHOULD ACT AS A CATALYST FOR LONGWAVE TROUGHING TO COMMENCE OVER THE
NE CONUS DURING THE SECOND HALF OF NEXT WEEK. IF THIS TREND
CONTINUES...THEN ANTICIPATE A RETURN TO WARMER TEMPS BUT SHOWERY
CONDITIONS WITH EACH PASSING DAY.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
SCTD SHWRS AND ISOLATED TSTMS CONTINUE OVER THE AREA IN
ASSOCIATION WITH A WEAK UPR TROF MOVING ACROSS THE AREA. HAVE
ATTEMPTED TO USE CURRENT RADAR TO TIME/PLACE ANY PRECIP IN TAFS
THROUGH 03Z. TROF MOVES ACROSS REGION THROUGH 12Z...WITH CHANCES
FOR SHWRS AND ISOLATED TSTMS PERSISTING. HAVE INCLUDED VCSH IN
TAFS BASED UPON THE TIMING SHOWN ON 18Z NAM. PRECIP SHOULD CLEAR
TERMINALS BY 13Z...LEAVING VFR CONDITIONS. THERE MAY BE SOME
ADDITIONAL SHWR/TSTM ACTIVITY THURSDAY AFTERNOON...BUT HAVE LEFT
OUT OF 00Z TAFS PRIMARILY DUE TO TIMING UNCERTAINTY. HAVE ALSO
INSERTED SOME FOG INTO THE KSBY TAF...BASED UPON PERSISTENCE AND
THE POTENTIAL FOR LESS CLOUDS THAN NAM TSECTIONS SUGGEST.
HOWEVER...HAVE NOT BROUGHT CONDITIONS TO LIFR AS OCCURRED LAST
NIGHT.
SCTD SHOWERS/TSTMS WILL REMAIN POSSIBLE THRU EARLY FRI...BEFORE A
COLD FRONT SWEEPS THRU HIGH PRESSURE WILL BUILD IN BEHIND THE
FRONT FOR FRI NGT THRU THE WEEKEND.
&&
.MARINE...
7 PM UPDATE...HAVE MADE SOME UPWARD ADJUSTMENTS TO WINDS/WAVES ON
THE CHESAPEAKE BAY...ESPECIALLY WESTERN SIDE...BASED UPON CURRENT
CONDITIONS AND LATEST HIGH RES MODEL OUTPUT. HRRR SEEMS TO HAVE A
GOOD HANDLE ON VERY SHORT TERM...AND HAVE USED IT AS PRIMARY WIND
GUIDANCE THROUGH 06Z THURSDAY. NO CHGS AFTER 06Z.
AFTERNOON DISCUSSION...LITTLE TO NO CHANGE TO ONGOING MARINE
FORECAST TONIGHT THROUGH MONDAY. WIND DIRECTIONS HAVE RETAINED
MORE OF A SE-S DIRECTION TODAY THAN PREVIOUSLY ANTICIPATED AND
HAVE INCREASED TO AROUND 10 KT. WINDS WILL CONTINUE TO SLOWLY VEER
TO THE S-SW OVERNIGHT AND INCREASE TWD 10-15 KT AS AN APPROACHING
TROUGH FROM THE OHIO VALLEY TIGHTENS THE PRESSURE GRADIENT OVER
THE WATERS. ALSO EXPECT SHOWER AND THUNDERSTORM CHANCES TO
INCREASE OVERNIGHT AS DECENT SHORTWAVE ENERGY/MOISTURE AND A JET
MAX ENHANCE LIFT/RAIN POTENTIAL. SHOWERS LINGER NEAR THE COAST
EARLY THURSDAY MORNING BUT THERE SHOULD BE A BRIEF REPRIEVE DURING
THE MID-LATE MORNING THROUGH EARLY AFTERNOON HOURS BEFORE
THUNDERSTORMS REGENERATE ALONG A COLD FRONT CROSSING THE WATERS
INTO THE EVENING. WINDS WILL BE PRIMARILY FROM THE SW AOB 15 KT ON
THURSDAY...THEN VEER TO THE W BY FRIDAY MORNING. SEAS WILL AVERAGE
2-3 FT AND WAVES ON CHES BAY WILL AVERAGE 1-2 FT.
THE FRONT STALLS ALONG THE CAROLINAS LATE THURSDAY NIGHT INTO AT
LEAST FRIDAY AFTERNOON...PROVIDING ADDITIONAL FOCUS/CHANCES FOR
AFTERNOON SHOWERS/STORMS ON FRIDAY. WINDS WILL START OUT FROM THE W
AND THEN VEER TO THE NW LATE IN THE AFTERNOON AS HIGH PRESSURE FROM
THE GREAT LAKES BEGINS TO SLIDE INTO THE REGION FROM THE NW. SPEEDS
STAY AOB 15 KT. THE FRONT FINALLY GETS PUSHED WELL SOUTH OF THE AREA
FRIDAY NIGHT BY THE LARGE-SCALE HIGH PRESSURE BUILDING INTO THE MID
ATLANTIC STATES THROUGHOUT THE WEEKEND. COOLER AND DRIER AIR WILL
ACCOMPANY THE HIGH AND QUICKLY BRING PRECIPITATION TO AN END FRIDAY
NIGHT. MODEL GUIDANCE WINDS CONTINUE TO KEEP WIND SPEEDS AOB 15 KT
AS THE COOLER AIR MOVES OVER WARMER WATERS FOR FRIDAY NIGHT INTO
SATURDAY. IN FACT...THEY ARE SHOWING AN INCREASE IN WINDS THROUGH
THE DAY ON SATURDAY AS THE COOL AIR FINALLY ARRIVES AND WINDS BECOME
NELY. WILL STILL MONITOR THE POTENTIAL FOR SCA CONDITIONS BUT NONE
ARE ANTICIPATED ATTM. SURFACE HIGH PRESSURE AND NE-E WINDS AOB 15 KT
SETTLE OVER THE WATERS THROUGHOUT THE WEEKEND. HIGH PRESSURE THEN
SLIDES SOUTHEAST OFF THE CAROLINA COAST ON MONDAY...SHIFTING WINDS
FROM E TO SE-S.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR
NCZ102.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...ESS
SHORT TERM...ESS
LONG TERM...BMD
AVIATION...WRS
MARINE...BMD/WRS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
734 PM EDT WED AUG 21 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 340 PM EDT WED AUG 21 2013
MAIN FOCUS OF THE FORECAST FOR TODAY IS THE DEVELOPING THUNDERSTORMS
ASSOCIATED WITH A COLD FRONT JUST STARTING TO MOVE INTO WESTERN
UPPER MICHIGAN. THE COLD FRONT HAS BEEN MAKING IT/S WAY
ACROSS WESTERN LAKE SUPERIOR AND NORTHWEST WISCONSIN OVER THE
LAST FEW HOURS AND THERE WAS SOME CONCERN THAT THE STRATUS DECK
THAT DEVELOPED FROM THE FOG NEAR DULUTH WOULD LIMIT COME OF THE
CONVECTION. BUT THE FORCING FROM THE COLD FRONT COMBINED WITH
DIURNAL HEATING HAS BEGAN TO PRODUCE THUNDERSTORMS ALONG THE COLD
FRONT WITH SOME BECOMING FAIRLY STRONG AT THIS WRITTING. WITH A
VERY UNSTABLE ATMOSPHERE (MLCAPE VALUES ANALYZED FROM 2000-3000
J/KG DUE TO SFC DEWPOINTS IN THE UPPER 60S AND LOWER 70S)...THEY
SHOULDN/T HAVE MUCH DIFFICULTY CONTINUING THROUGH THE EARLY EVENING.
AS HAS BEEN MENTIONED OVER THE LAST COUPLE OF DAYS...0-6KM SHEAR
VALUES ARE A LITTLE MARGINAL...BUT LATEST RAP TRENDS SHOW VALUES
APPROACHING 30-35KTS RIGHT ALONG THE COLD FRONT. THIS SHOULD HELP
THE THUNDERSTORMS BECOME A LITTLE MORE TILTED AND BETTER ORGANIZED
OVER THE NEXT FEW HOURS. THINKING THAT THERE IS A DECENT CHANCE OF
THIS CONVECTION BECOMING LINEAR AND MOVING ACROSS MUCH OF UPPER
MICHIGAN LATE THIS AFTERNOON AND INTO THE EVENING. DAMAGING WIND IS
A DECENT THREAT WITH DCAPE VALUES AHEAD OF THE FRONT OF 800-1100
J/KG. WHERE THERE ARE STRONGER STORMS...HAIL IS ALSO A THREAT...BUT
IT WILL LIKELY BE MORE ISOLATED DUE TO THE HIGHER FREEZING LEVELS.
WITH THE BOUNDARIES OVER THE WEST AND LOWER LCL HEIGHTS FROM THE
LEFT OVER STRATUS...THERE COULD BE A ISOLATED TORNADO THREAT...BUT
SHOULD BE CONFINED TO THE LATE AFTERNOON. IN ADDITION...ANOTHER
BOUNDARY (AIDED BY EARLIER CLOUDS/SHOWERS THAT MOVED ACROSS NORTHERN
LAKE SUPERIOR) HAS SETUP FROM WEST TO EAST FROM ONTONAGON THROUGH
MARQUETTE COUNTY. SHOWERS/THUNDERSTORMS HAVE ALSO STARTED TO DEVELOP
ALONG THIS AND ARE SLIDING EAST. SPC HAS JUST ISSUED A SEVERE
THUNDERSTORM WATCH FOR MUCH OF UPPER MICHIGAN THROUGH 4Z. THE COLD
FRONT AND THUNDERSTORMS ARE EXPECTED TO EXIT INTO LAKE MICHIGAN
AROUND 06Z. PREVIOUS FORECAST HAD A GOOD HANDLE ON TIMING...SO ONLY
MADE MINOR ADJUSTMENTS.
THE REST OF THE NIGHT SHOULD BE DRY (DUE TO DRIER AIR SURGING IN
BEHIND THE COLD FRONT)...EVENTHOUGH A FAIRLY POTENT SHORTWAVE WILL
BE SLIDING SOUTHEAST ACROSS THE AREA FROM LAKE WINNIPEG. THIS
SHOULD LEAD TO MOSTLY CLEAR SKIES AND MUCH COOLER TEMPERATURES THAN
LAST NIGHT.
COOLER NORTHERLY FLOW WILL BE IN STORE FOR UPPER MICHIGAN ON
THURSDAY...AS HIGH PRESSURE APPROACHES THE AREA FROM THE UPPER
MISSISSIPPI VALLEY. 850MB TEMPS WILL BE AROUND 10C COOLER THAN
TODAY AND EXPECT A SIMILAR RESPONSE WITH THE HIGHS (IN THE 70S).
COOLEST TEMPERATURES WILL BE NEAR LAKE SUPERIOR...WHERE THE
NORTHERLY WINDS OFF THE LAKE WILL KEEP TEMPS RIGHT AROUND 70. A
SUNNY TO MOSTLY SUNNY SKY IS EXPECTED.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 340 PM EDT WED AUG 21 2013
NAM SHOWS A 500 MB RIDGE ACROSS THE ROCKIES AND CENTRAL PLAINS WITH
A TROUGH OVER THE ERN U.S. 00Z FRI. THE 500 MB RIDGE BUILDS INTO THE
CENTRAL PLAINS THIS FORECAST PERIOD WITH THE EDGE OF THE WESTERLIES
OVER THE AREA THIS FORECAST PERIOD. DID PUT IN SLIGHT CHANCE TO
CHANCE POPS IN THE FORECAST FOR THE WEST HALF FOR SAT AFTERNOON AS A
WARM FRONT HEADS TOWARDS THE AREA AND MOISTURE STARTS TO INCREASE.
OTHERWISE...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST FOR
TEMPERATURES. LOOKS TO STAY WARM THROUGH THIS PERIOD.
IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB RIDGE OVER THE CENTRAL
U.S. SAT NIGHT INTO SUN. THE RIDGE REMAINS STATIONARY THROUGH THE
PERIOD WITH THE U.P. IN THE PERIPHERY OF THE RIDGE IN THE RING OF
FIRE SCENARIO WHERE ANY SHORTWAVE CAN SET OFF A ROUND OF
THUNDERSTORMS. WILL BE HARD TO TIME THESE SHORTWAVES AND EASIEST WAY
TO FORECAST THIS WOULD BE TO BROADBRUSH THIS FORECAST PERIOD WITH
CHANCE POPS EVEN THOUGH IT WILL NOT BE A TOTAL WASHOUT. TEMPERATURES
WILL STAY ABOVE NORMAL FOR THIS FORECAST PERIOD ALONG WITH
INCREASING HUMIDITY. ONLY PERIOD THAT LOOKS DRY IS WED WITH A FRONT
MOVING OUT OF THE AREA.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 732 PM EDT WED AUG 21 2013
BEHIND A COLD FRONT THAT HAS MOVED THROUGH THE AREA...
VFR CONDITIONS WILL PREVAIL TONIGHT AND THURSDAY AS HIGH PRESSURE
BUILDS OVER THE AREA.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 340 PM EDT WED AUG 21 2013
A COLD FRONT CURRENTLY MOVING ACROSS CENTRAL LAKE SUPERIOR WILL
CONTINUE SOUTHEAST THIS EVENING AND LEAD TO NORTHERLY FLOW
(GENERALLY BELOW 15KTS) OVER THE LAKE FOR THE REST OF TONIGHT AND
INTO THURSDAY EVENING. HIGH PRESSURE THAT IS PRODUCING THE LIGHTER
WINDS WILL THEN SHIFT SOUTHEAST INTO THE LOWER GREAT LAKES AND
ALLOW WINDS TO SLOWLY INCREASE FROM THE SOUTH-SOUTHWEST FRIDAY INTO
THE WEEKEND. AT THIS POINT...WOULD EXPECT LAKE STABILITY FACTORS TO
KEEP WINDS AT OR BELOW 20KTS.
ONE FINAL ITEM TO MENTION IS IF THE SHOWERS/THUNDERSTORMS AFFECT
ENOUGH OF EASTERN LAKE SUPERIOR TO DEVELOP FOG. LEFT OUT AT THIS
POINT SINCE VISIBLE SATELLITE INDICATED THE FOG OVER NORTHERN LAKE
SUPERIOR HAS DISSIPATED AND THERE IS SOME UNCERTAINTY ON HOW FAR
THE RAIN WILL GET INTO EASTERN LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...07
AVIATION...JLB
MARINE...SRF
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
707 PM EDT WED AUG 21 2013
.AVIATION...
//DISCUSSION...
DIURNAL CU FIELD WILL CONTINUE TO DISSIPATE EARLY THIS EVENING AS
THE SUN SETS. HOWEVER CLOUDS ARE EXPECTED TO THICKEN AND BECOME
BKN-OVC OVERNIGHT AS A COLD FRONT APPROACHES FROM THE NORTHWEST.
CIGS WITH THIS FRONT ARE EXPECTED TO BE AROUND 5KFT...HOWEVER VSBYS
COULD DROP TO MVFR IN RAIN SHOWERS AND THUNDERSTORMS ACROSS THE
NORTHERN AIRPORTS NEAR THE PRE-FRONTAL TROUGH THAT WILL HAVE SOME
INSTABILITY TO WORK WITH BEFORE DISSIPATING. WINDS SHIFT TO THE
NORTH THURSDAY WITH PLENTY OF DRY AIR RETURNING THINGS TO VFR AFTER
THE RAIN.
FOR DTW...BEST THUNDERSTORM CHARACTERISTICS APPEAR TO BE FURTHER
NORTH...SO LEFT TS OUT OF THE TAFS THIS PERIOD. WILL UPDATE WITH AMD
IF NEEDED...BUT DTW WILL LIKELY DROP TO 4SM WITH STRONGEST SHOWERS.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE OF CEILINGS BELOW 5000 FEET AFTER 12Z TONIGHT.
&&
.PREV DISCUSSION...ISSUED 339 PM EDT WED AUG 21 2013
SHORT TERM...TONIGHT
VIS SATELLITE AND RADAR SHOW VERY SMALL AREAS OF SHOWERS ALONG AN
AREA OF MOISTURE CONVERGENCE FROM JYM TO PTK. THIS WAS DEPICTED WELL
WITH THE HRRR AS A DIURNAL CONVECTIVE SHOWER EVENT THAT WILL SWING
EAST AND SOUTH...DYING WITH THE LOSS OF DAYTIME HEATING. 20-30 POP
GRIDS WERE UPDATED EARLIER TO INCLUDE THIS CHANCE...WHICH WILL END
NLT 00Z.
CLOUDS AND PRECIP CHANCES INCREASE FROM NW TO SE TONIGHT AS A COLD
FRONT APPROACHES FROM THE NORTHWEST. THERE WILL BE SOME ELEVATED
INSTABILITY...ESPECIALLY NORTH OF I-69 OVERNIGHT AS LI/S ARE -2 OR
-3 AND ABOUT 1000 J/KG OF CAPE IS PRESENT ABOVE 800 MB. WINDS WILL
ALSO VEER AND INCREASE WITH HEIGHT IN THE ELEVATED LAYER
OVERNIGHT...LEADING TO HIGHER POPS TO INCLUDE THUNDER IN THE
FORECAST. THESE CONDITIONS WILL SWING SOUTHEASTWARD THROUGH THE
STATE...BUT HIGHER PW/S (2.0 INCHES) AND LESS INSTABILITY BRING THE
FORECAST TO LOWER THUNDER CHANCES SOUTH OF M-59.
LONG TERM...THURSDAY THROUGH TUESDAY
A WELL-DEFINED 110KT JET IS EVIDENT ALONG THE US/CANADA BORDER THIS
AFTERNOON AS THE UPPER GRADIENT TIGHTENS BETWEEN THE EXPANSIVE
WESTERN U.S. RIDGE AND SHORTWAVE ENERGY DIGGING INTO SOUTHEAST
SASKATCHEWAN AND SOUTHWEST MANITOBA. MESOANALYSIS REVEALS AN
ORGANIZING LOW-LEVEL BAROCLINIC ZONE ASSOCIATED WITH THIS JET THAT
IS BEGINNING TO FEEL ITS WAY SOUTHEAST AS THE LARGE SCALE TROUGH
OVER CENTRAL AND EASTERN CANADA BEGINS TO SWEEP ACROSS THE GREAT
LAKES. RELATIVELY LITTLE HAS CHANGED WITH REGARD TO FORECAST
REASONING. INITIALLY, SOME REMNANT SHOWERS WILL BE POSSIBLE IN
ADVANCE OF THE FRONT IN ASSOCIATION WITH ANY UPSTREAM DEVELOPMENT
OVER WISCONSIN THIS EVENING, ALTHOUGH CONFIDENCE IS NOT PARTICULARLY
HIGH IN THE DEGREE OF COVERAGE EARLY IN THE PERIOD GIVEN THE LACK OF
LARGE SCALE SUPPORT. STILL, EITHER WEAKLY ORGANIZED RIGHT ENTRANCE
SUPPORT, A CONVECTIVELY ENHANCED WAVE EMANATING OUT OF UPSTREAM
ACTIVITY, OR A COMBINATION OF BOTH, STILL WARRANT A CONTINUATION OF
LIKELY POPS ACROSS MUCH OF THE AREA DURING THE FIRST HALF OF THE
DAY.
UNCERTAINTY FURTHER INCREASES FOR THURSDAY AFTERNOON AS BOUNDARY
LAYER RECOVERY WILL BE STRONGLY DEPENDENT ON CLOUD COVER AND
DURATION OF MORNING SHOWERS. THE NAM/GFS REPRESENT THE AGGRESSIVE
SIDE OF THE ENVELOPE WITH UP TO 3000 J/KG SBCAPE DEVELOPING BY MID
AFTERNOON WHEREAS THE GENERAL CONSENSUS OF BOTH HIGHER RESOLUTION
GUIDANCE SUCH AS THE NMM/ARW AS WELL AS THE GEM/ECMWF ALLOW HIGH
PRESSURE TO AGGRESSIVELY BUILD IN WITH LITTLE MORE THAN A LOW
COVERAGE OF AFTERNOON SHOWERS TO SHOW FOR THE FROPA. GIVEN THE
DEGREE OF UNCERTAINTY, FELT IT PRUDENT TO TAPER POPS BACK INTO THE
HIGH CHANCE CATEGORY ESSENTIALLY EVERYWHERE ALONG/NORTH OF I-94,
WHICH REFLECTS THE LATEST FORECAST REASONING BUT STILL LEAVES ROOM
FOR ADJUSTMENT IN EITHER DIRECTION AS NEW DATA BECOMES AVAILABLE.
FOR FAR SOUTHERN AREAS, ENOUGH RECOVERY WILL BE POSSIBLE TO SUPPORT
A PULSE SEVERE THREAT IMMEDIATELY AHEAD OF THE FRONT, BUT WITH THE
BETTER SHEAR LAGGING BEHIND, THE THREAT FOR ORGANIZED SEVERE WEATHER
REMAINS LOW. TEMPERATURES WILL FALL BACK TO NEAR 80 FOR THE WEEKEND
AS COOLER AND DRIER AIR FILTERS INTO SOUTHEAST MI IN THE WAKE OF THE
FRONT AND HIGH PRESSURE SETTLES OVER THE NORTHEASTERN UNITED STATES.
THERE WILL BE NUMEROUS CHANCES FOR THUNDERSTORMS NEXT WEEK AS THE
CWA WILL BE POSITIONED ALONG THE NE PERIPHERY OF THE BUILDING 595DM
RIDGE OVER THE CENTRAL U.S. WHILE REMAINING IN CLOSE PROXIMITY TO
PREVAILING WESTERLY FLOW. THIS WILL SET THE STAGE FOR MULTIPLE
CONVECTIVE COMPLEXES TO AFFECT SOME OR ALL OF THE REGION. INITIAL
EXPECTATIONS ARE THEREFORE FOR THUNDERSTORM ACTIVITY IN THE VICINITY
TO HELP KEEP TEMPERATURES IN CHECK, BUT WITH H5 HEIGHTS IN THE
585-588DM RANGE AND H85 TEMPS NEAR 20C, THE POTENTIAL FOR HIGHS TO
REACH INTO THE 90S WILL EXIST ON BASICALLY ANY DAY FROM MONDAY
ONWARD.
MARINE...
A PRESSURE GRADIENT BETWEEN HIGH PRESSURE IN THE MID-ATLANTIC AND
LOW PRESSURE OVER HUDSON BAY WILL PROVIDE INCREASED SW WINDS
TONIGHT. AIR TEMPERATURES WILL STAY PRETTY WARM UNTIL THE COLD FRONT
SWINGS THROUGH EARLY THURSDAY...SO THERE IS NOT MUCH INSTABILITY
OVER THE LAKES UNTIL THEN. OFFSHORE WINDS WILL BECOME MORE ONSHORE
LATE THURSDAY AND WILL HELP INCREASE WAVE HEIGHTS ALONG THE THUMB`S
SHORE TO 3 FEET. WILL WATCH FOR SMALLCRAFT CONDITIONS NEXT FORECAST
PERIOD...BUT IN THE MEANTIME SIG/MAX WAVES SHOULD STAY MANAGEABLE.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....KURIMSKI
SHORT TERM...MM
LONG TERM....JVC
MARINE.......MM
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
418 PM EDT TUE AUG 20 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 416 PM EDT TUE AUG 20 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL MID/UPPER LEVEL
FLOW ACROSS SRN CANADA AND THE NRN CONUS ATOP RIDING OVER THE PLAINS
AND A CUTOFF LOW NEAR KSTL. THE MAIN UPSTREAM SHORTWAVE TROUGH WAS
LOCATED WELL UPSTREAM...FROM SASK INTO ERN ALBERTA. AT THE SFC...SW
FLOW PREVAILED THROUGH THE WRN GREAT LAKES BTWN HIGH PRES OVER THE
ERN OH VALLEY AND A TROUGH FROM NW ONTARIO INTO CNTRL ND. A COLD
FRONT EXTENDED FROM NEAR WINNIPEG INTO SRN SASK. ALTHOUGH VIS LOOP
SHOWED ABUNDANT CU ACROSS THE REGION AND A LAKE BREEZE BOUNDARY OFF
OF LAKE MI...CAPPING EVIDENT ON AREA SOUNDINGS WITH 800-700 MB TEMPS
AROUND 13C HAS SUPPRESSED ANY CONVECTION THAT WOULD PRODUCE ANY
SHRA/TSRA.
TONIGHT...AS THE ALBERTA/SASK MOVES INTO MANITOBA AND THE PLAINS
TROUGH SLIDES TO THE EAST THE STRONGEST LOW LEVEL MOISTURE
ADVECTION...FOCUS OF THE LOW LEVEL JET...AND 310K ISENTROPIC LIFT
THROUGH THE 850-700 MB FRONT WILL REMAIN JUST NORTH OF LAKE SUPERIOR
BUT MAY BRUSH THE NRN PORTION OF THE LAKE. OTHERWISE...THE PERSISTENT
SW FLOW THROUGH THE WRN LAKES WILL KEEP TEMPS WELL ABOVE
NORMAL...ESPECIALLY FOR DOWNSLOPE LOCATIONS NEAR LAKE SUPERIOR. MIN
READINGS IN THE MID 60S TO LOWER 70S...NEAR THE HIGHER END OF
GUIDANCE ARE EXPECTED.
WED...AS THE SHRTWV MOVES THROUGH NRN ONTARIO IT WILL DRAG THE COLD
FRONT THROUGH LAKE SUPERIOR AND UPPER MI. THE COMBINATION OF LOW
LEVEL CONV ALONG THE FRONT...REINFORCED BY THE LAKE SUPERIOR
BREEZE...AND WEAK TO MODERATE MID LEVEL QVECTOR CONV WITH THE TAIL
OF THE SHRTWV SHOULD TRIGGER TSRA OVER WEST UPPER MI IN THE EARLY
AFTERNOON WHICH WILL SPREAD INTO THE CNTRL CWA BY MID AND LATE
AFTERNOON. DEWPOINTS INTO THE UPPER 60S AND TEMPS IN THE UPPER 80S
WILL RESULT IN MLCAPE VALUES INTO THE 2K-3K J/KG RANGE. THE STRONG
INSTABILITY(BY U.P. STANDARDS) ALONG WITH 0-6KM SHEAR TO AROUND 30
KT WILL BE ENOUGH TO SUPPORT MULTICELL CLUSTERS WITH SOME SEVERE
THUNDERSTORMS. WITH DCAPE VALUES OF 1K J/KG...DAMAGING WINDS WILL BE
THE MAIN THREAT. SOME ISOLATED LARGE HAIL MAY ALSO BE POSSIBLE WITH
THE STRONGEST STORMS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 416 PM EDT TUE AUG 20 2013
COLD FRONT AND ASSOCIATED SHOWERS/THUNDERSTORMS WILL BE MOVING
SOUTHEAST ACROSS CENTRAL AND EASTERN UPPER MICHIGAN AT THE
START OF THE LONG TERM PERIOD. EXPECT THESE STRONG TO POTENTIALLY
SEVERE THUNDERSTORMS TO BE SLIDING EAST-SOUTHEAST ACROSS THOSE AREAS
DURING THE EVENING HOURS AND BE MOVING INTO LAKE MICHIGAN TOWARDS
MIDNIGHT OR THE EARLY OVERNIGHT HOURS. 12Z MODELS TODAY SEEM TO BE
A LITTLE SLOWER WITH THE FRONTAL PASSAGE THAN YESTERDAY...SO WILL
FOLLOW THE IDEA OF THE MID SHIFT WITH THE TIMING.
A SHORTWAVE DIVING SOUTHEAST FROM LAKE WINNIPEG WEDNESDAY NIGHT
WILL CROSS THE U.P. ON THURSDAY MORNING. WITH THE DRY AIR AND
HIGH PRESSURE THAT ARRIVES BEHIND THE COLD FRONT...SHOULDN/T SEE
MUCH INFLUENCE FROM THE SHORTWAVE ON THE WEATHER AND EXPECT MOSTLY
SUNNY SKIES. HIGHS THURSDAY WILL BE MUCH COOLER (BY 10-15
DEGREES) THAN WEDNESDAY WITH THE NORTHERLY WINDS OFF LAKE SUPERIOR.
FORTUNATELY...MOST AREAS WILL SEE RAIN TOMORROW...OTHERWISE THERE
COULD BE AN ELEVATED FIRE WX RISK WITH NORTH WINDS OF 10-20MPH AND
RH VALUES FALLING TOWARDS 30 PERCENT.
ANOTHER SHORTWAVE ROUNDING THE UPPER RIDGE IN CENTRAL CANADA WILL
DIVE SOUTHEAST ACROSS THE EASTERN CWA ON FRIDAY. AT THIS
TIME...WOULD EXPECT SOME INCREASE IN CLOUD COVER BASED OFF
925-850MB MOISTURE AND DIURNAL HEATING OVER THE EASTERN PART OF THE
CWA (MAINLY FROM MARQUETTE/DICKINSON COUNTIES AND EAST). WON/T GO
TOO HIGH ON CLOUD COVER...BUT AT LEAST GIVE A PERIOD OF PARTLY
CLOUDY SKIES OVER THE EAST AS THAT MOISTURE MOVES THROUGH.
UPPER RIDGE THAT WAS OVER THE NORTHERN PLAINS AND CENTRAL CANADA
WILL THEN SHIFT EAST ON FRIDAY NIGHT WITH THE AXIS OF THE RIDGE
OVER UPPER MICHIGAN BY 12Z SATURDAY. THIS MOVEMENT OF THE RIDGE
WILL ALSO SLIDE THE SURFACE HIGH EAST OF THE AREA AND ALLOW
SOUTHERLY FLOW AND GRADUALLY WARMING TEMPERATURES TO RETURN. MODELS
ARE STILL STRUGGLING TO COME UP WITH A CONSENSUS ON THE SERIES OF
SHORTWAVES MOVING INTO THE UPPER RIDGE AND GRADUALLY BREAKING IT
DOWN FROM SATURDAY AFTERNOON THROUGH THE FIRST HALF OF NEXT WEEK.
THE FIRST WAVE WILL MOVE THROUGH THE AREA SATURDAY AFTERNOON AND
NIGHT (OVER THE NORTH HALF OF THE CWA) AND THE NEXT ONE LATE SUNDAY
AFTERNOON INTO MONDAY MORNING. THE DISCREPANCIES GROW FURTHER ON
MONDAY NIGHT INTO TUESDAY...WITH GFS BRINGING ANOTHER SHORTWAVE
THROUGH ON TUESDAY WHILE THE ECMWF/GEM HAS HIGH PRESSURE OVER THE
AREA. THESE PERIODS OF SHOWERS/THUNDERSTORMS ALSO LEADS TO
UNCERTAINTY WITH HIGHS BUT SHOULD AT LEAST BE ABOVE NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 136 PM EDT TUE AUG 20 2013
EXPECT VFR CONDITIONS THROUGH THE FORECAST PERIOD AT ALL 3 TAF SITES
WITH A RELATIVELY DRY/CAPPED LOW LEVEL AIRMASS DOMINATING. GUSTY SW
WINDS AIDED BY DAYTIMME HEATING/MIXING WILL DIMINISH LATE TODAY.
AFTER SUNSET AN INVERSION WL FORM AND RESULT IN LLWS WITH
STRENGTHENING NOCTURNAL SW LOW LEVEL JET UNDER A SHARPENING PRES
GRADIENT AHEAD OF APPROACHING COLD FRONT. ANY SHRA/TSRA WITH THE
FRONT ARE EXPECTED TO HOLD OFF UNTIL AFTER THE TAF PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 416 PM EDT TUE AUG 20 2013
OVERALL...EXPECT WINDS LESS THAN 20KT THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. ONE PERIOD OF STRONGER WINDS (GUSTS TO 20-25KT)
MAY OCCUR TONIGHT AS THE PRES GRADIENT TIGHTENS AHEAD OF THE
APPROACHING COLD FRONT...BUT HIGH OVERWATER STABILITY WITH INFLUX
OF A VERY WARM AIRMASS WILL LIMIT THE INCREASE OF WIND SPEED NEAR THE
COOLER LAKE SURFACE. THE ARRIVAL OF MORE HUMID AIR MAY RESULT IN
SOME FOG FORMATION OVER THE COOLER LAKE WATERS...BUT RESTRICTED THE
FOG FORECAST TO AREAS WHERE SOME SHOWERS OR THUNDERSTORMS ARE
EXPECTED. ANY FOG WILL DISSIPATE WED AFTN AND EVENING FOLLOWING A
COLD FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
136 PM EDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM EDT TUE AUG 20 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW REBOUNDING UPR RDG
INTO THE UPR GRT LKS ON THE SRN FLANK OF ZONAL FLOW OVER CANADA. A
PRONOUNCED H5 THERMAL RDG IS EVIDENT STRETCHING FM THE NRN PLAINS
THRU NW MN AND INTO NW ONTARIO...WITH THE 00Z H5 TEMP UP TO -7C AT
INL...COMPARED TO THE -11C OBS AT APX CLOSER TO DEPARTING SHRTWV IN
THE CENTRAL LKS. THE COMBINATION OF THE ASSOCIATED MID LVL CAPPING
AND SUBSIDENCE RELATED TO DEEP LYR QVECTOR DVGC ACCOMPANYING THE
BLDG RDG IS RESULTING IN MOCLR SKIES OVER THE CWA EARLY THIS MRNG
DESPITE ADVECTION OF SOMEWHAT HIER LLVL MSTR WITH H85 DEWPTS UP TO
16C AT MPX IN THE SW FLOW ARND SFC HI PRES IN THE MID ATLANTIC
STATES. DESPITE THE MOCLR SKIES...THE STEADY SW FLOW IS RESULTING IN
ABV NORMAL TEMPS EARLY THIS MRNG...ESPECIALLY OVER THE W HALF OF UPR
MI IN THE DOWNSLOPE AREAS NEAR LK SUP...WHERE READINGS ARE HAVING A
HARD TIME FALLING BLO 70. BUT EVEN WARMER AIR IS TO THE W...WITH 00Z
H85 TEMPS RANGING FM 14C AT GRB AND APX TO 17C AT MPX...19C AT
INL...AND A TOASTY 25C AT BISMARCK. THERE IS ANOTHER SHRTWV SHIFTING
EWD THRU THE NRN PLAINS...BUT THE 00Z BISMARCK RAOB IS SO DRY THERE
IS NO PCPN OR EVEN ANY CLD COVER.
MAIN FCST CONCERNS IN THE SHORT TERM FOCUS ON TEMPS AND SMALL SHRA/
TS CHCS.
TODAY...UPR MI IS FCST TO REMAIN UNDER THE UPR RDG AXIS...WITH H5
THERMAL RDG/TEMPS ARND -7C NOTED ABOVE SHIFTING OVHD IN MID LVL
SUBSIDENCE REGIME. CONTINUED SW FLOW ARND STAGNANT SFC HI PRES IN
THE MID ATLANTIC IS FCST TO LIFT H85 TEMPS UP TO 17-18C OVER THE E
TO 18-19C OVER THE W BY 00Z WED. MIXING TO H8 ON GFS/NAM FCST SDNGS
YIELDS HI TEMPS REACHING TO ARND 90 AWAY FM THE COOLING INFLUENCE OF
LK MI...SO PREFER TO HEDGE TOWARD THE HI END OF GUIDANCE FOR MAX
TEMPS FCST. THIS SW FLOW WL ALSO ADVECT THE HIER LLVL MSTR SHOWN ON
THE 00Z MPX RAOB INTO THE UPR LKS...RESULTING IN A MORE HUMID AND
UNCOMFORTABLE DAY AS SFC DEWPTS RUN WELL INTO THE 60S. DESPITE THE
INCRSG HEAT/HUMIDITY THAT WL LIFT MUCAPE AOA 2000J/KG THIS AFTN PER
MODIFIED GFS/NAM FCST SDNGS FOR SFC T/TD 90/65...SUSPECT THE MID LVL
WARMTH/DRYNESS/STABILITY WL SUPPRESS CONVECTION. ONE POSITIVE FOR
SHRA/TS WOULD BE THE APRCH LATER THIS AFTN OF SHRTWV NOW MOVING THRU
THE NRN PLAINS...BUT CONSIDERING GFS/NAM MOS POPS AOB 10 PCT...
PRESENCE OF VERY WARM H5 AIR/SHARPER CAPPING...AND ABSENCE OF
APPRECIABLE LK BREEZE CNVGC WITH SUPPRESSION OF LK SUP BREEZE IN
SYNOPTIC SW FLOW...OPTED TO GO DRY FOR THE ENTIRE CWA TODAY.
TNGT...STEADY SW FLOW WITH H925 WINDS UP TO 30-35KTS UNDER
SHARPENING PRES GRADIENT BTWN MID ATLANTIC HI PRES AND APRCHG COLD
FNT IN MN ASSOCIATED WITH SHRTWV RIDING E IN THE ZONAL FLOW THRU
CANADA IS FCST TO LIFT H85 TEMPS AOA 20C OVER THE WRN CWA OVERNGT.
WL TEND AOA THE HI END OF GUIDANCE FOR MIN TEMPS...ESPECIALLY IN THE
DOWNSLOPE AREAS NEAR LK SUP OVER THE W HALF. CONCERNED THE ARRIVAL
OF SOME DEEP LYR QVECTOR CNVGC/STEEPENING LAPSE RATES WITH FALLING
H5 TEMPS TOWARD -10C IN ADVANCE OF THE FNT LATE TNGT MIGHT GENERATE
SOME SHRA/TS OVER AT LEAST THE NW HALF OF THE CWA. ALTHOUGH THE BULK
OF THE NUMERICAL MODELS SHOW A DRY FCST FOR THE CWA THRU 12Z WED...
OPTED TO RETAIN SOME SCHC POPS OVER THE MAINLY WRN/NCENTRAL LK SUP
SINCE THERE WL BE SOME DYNAMIC SUPPORT AND THE GFS AS WELL AS THE
LOCAL WRF/ARW MODELS DO GENERATE SOME PCPN.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 405 AM EDT TUE AUG 20 2013
NOT TOO MUCH HAS CHANGED SINCE 24 HOURS AGO...AND AM WELL IN
AGREEMENT WITH THE PREVIOUS SHIFT. STILL HAVE SOME
UNCERTAINTY...ESPECIALLY WITH SOME SPECIFIC ITEMS...BUT WILL TALK
ABOUT THAT IN MORE DETAIL BELOW.
FOR WED...A NRN STREAM TROUGH WILL SLIDE ACROSS THE CWA WED INTO WED
NIGHT...WHICH WILL BRING INCREASED CHANCES OF PRECIP FOR THAT
PERIOD. WITH 850MB TEMPS AROUND 20C AT PEAK HEATING WED
AFTERNOON...HIGH TEMPS AHEAD OF THE FRONT AND ASSOCIATED PRECIP AND
CLOUD COVER SHOULD BE ABLE TO GET INTO THE LOW 90S /AWAY FROM LAKE
MICHIGAN FROM MODERATING SW WINDS AND IMMEDIATE SHORES OF LAKE
SUPERIOR/. THE SW-NE ORIENTED COLD FRONT LOOKS TO MOVE INTO WRN
UPPER MI AROUND 18Z WED...WITH SOME VARIABILITY BETWEEN THE MODELS
/ECMWF AND GFS SHOWING THIS SOLUTION AND THE NAM AND GEM BEING
FASTER/. BY 00Z THU...MODELS SHOW THE COLD FRONT FROM ERN LAKE
SUPERIOR INTO SCENTRAL UPPER MI...WITH THE FRONT JUST E OF THE CWA
BY 06Z THU. SHOULD SEE CAPE VALUES OF 1500-2500J/KG AND POSSIBLY AS
HIGH AS 3000J/KG AHEAD OF THE FRONT. 0-6KM SHEAR LOOKS TO BE ON THE
LOW SIDE FOR ORGANIZED THUNDERSTORMS AT AROUND 20KTS...AND THAT IS
MOSTLY UNIDIRECTIONAL. STORM MODE SHOULD BE MULTICELL CLUSTERS AND
BEST THREAT FOR SEVERE WEATHER WILL BE MORE ISOLATED DAMAGING
WINDS...ESPECIALLY OVER THE SCENTRAL CWA WHERE DCAPE VALUES WILL BE
ENHANCED. HAIL THREAT WILL BE MORE MINIMAL DUE TO WEAK SHEAR AND THE
FREEZING LEVEL BEING AROUND 12KFT. WILL CONTINUE TO SHOW LIKELY POPS
OVER MUCH OF THE AREA TIMED CLOSE TO EXPECTED FROPA. WITH THE
UNCERTAINTY IN FRONTAL TIMING...HIGH TEMPS MAY BE MORE IN JEOPARDY
IF THE FRONT COMES THROUGH FASTER AND CONVECTIVE COVERAGE/INTENSITY
IS MORE UNCERTAIN.
BY LATE WED NIGHT...SHOULD SEE ALL PRECIP AND MOST CLOUDS CLEARED
OUT AS AS SFC HIGH MOVES IN FROM THE W...AND WITH 850MB TEMPS AROUND
12C BY 12Z THU...LOW TEMPS SHOULD BE ABLE TO QUICKLY FALL OFF TO
AROUND 50F OVER PARTS OF THE INTERIOR W.
WHILE A COUPLE OF UPPER SHORTWAVES MOVE THROUGH THU AND FRI...THE
SFC HIGH WILL BE DIRECTLY OVER THE CWA LATE THU INTO THU NIGHT...AND
WILL HAVE JUST MOVED E OFF THE CWA BY LATE FRI...SO IT WILL BE TOO
DRY FOR ANY PRECIP OVER THE CWA RESULTING FROM THE SHORTWAVES. 850MB
TEMPS COOL SOME MORE WITH CONTINUED NLY FLOW AND THE SHORTWAVE ON
THU TO AROUND 10-11C...RESULTING IN MUCH COOLER HIGH TEMPS IN THE
70S /OR POSSIBLY LOW 80S OVER FAR SCENTRAL UPPER MI/. FRI TEMPS LOOK
SIMILAR IF NOT A DEGREE OR TWO COOLER IN MOST LOCATIONS.
MORE UNCERTAIN ON LATER TIME FRAMES...BUT SOME PRECIP LOOKS POSSIBLE
LATE FRI NIGHT INTO EARLY SAT NIGHT AS A WARM FRONT/WAA MOVES INTO
THE CWA. MODELS AGREE ON BRINGING UPPER RIDGING ACROSS THE CWA SAT
AND SUN...RESULTING IN 850MB TEMPS INCREASING TO AROUND 20C BY 00Z
MON. THINK TEMPS MAY BE TOO LOW IN THE EXTENDED /SOMEWHAT FOR
SAT...BUT MORE SO FOR SUN/...BUT UNCERTAINTY RELATING TO PRECIP/CLOUDS
MAKES IT HARD TO JUSTIFY INCREASING TEMPS SIGNIFICANTLY. THINK THAT
CONSENSUS OF GUIDANCE WILL BE FAIRLY REPRESENTATIVE FOR SAT AND SUN.
MUCH DECREASED CONFIDENCE ON MON AS MODELS HAVE DIFFICULTY HANDLING
CONVECTION POSSIBILITIES NEAR/OVER THE CWA. WILL CONTINUE TO USE
CONSENSUS OF GUIDANCE FOR MON GIVEN THE LIMITED CONFIDENCE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 136 PM EDT TUE AUG 20 2013
EXPECT VFR CONDITIONS THROUGH THE FORECAST PERIOD AT ALL 3 TAF SITES
WITH A RELATIVELY DRY/CAPPED LOW LEVEL AIRMASS DOMINATING. GUSTY SW
WINDS AIDED BY DAYTIMME HEATING/MIXING WILL DIMINISH LATE TODAY.
AFTER SUNSET AN INVERSION WL FORM AND RESULT IN LLWS WITH
STRENGTHENING NOCTURNAL SW LOW LEVEL JET UNDER A SHARPENING PRES
GRADIENT AHEAD OF APPROACHING COLD FRONT. ANY SHRA/TSRA WITH THE
FRONT ARE EXPECTED TO HOLD OFF UNTIL AFTER THE TAF PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 405 AM EDT TUE AUG 20 2013
OVERALL...EXPECT WINDS LESS THAN 20KT THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. ONE PERIOD OF STRONGER WINDS (GUSTS TO 20-25KT)
MAY OCCUR TONIGHT AS PRES GRADIENT TIGHTENS AHEAD OF APPROACHING
COLD FRONT...BUT HI OVERWATER STABILITY WITH INFLUX OF VERY WARM
AIRMASS WILL LIMIT THE INCREASE OF WIND SPEED NEAR THE COOLER LAKE
SURFACE. THE ARRIVAL OF MORE HUMID AIR MAY RESULT IN SOME FOG
FORMATION OVER THE COOLER LAKE WATERS...BUT RESTRICTED THE FOG
FORECAST TO AREAS WHERE SOME SHOWERS OR THUNDERSTORMS ARE EXPECTED.
ANY FOG WILL DISSIPATE WED AFTN/EVENING FOLLOWING A COLD FRONTAL
PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...JLB
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
729 AM EDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM EDT TUE AUG 20 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW REBOUNDING UPR RDG
INTO THE UPR GRT LKS ON THE SRN FLANK OF ZONAL FLOW OVER CANADA. A
PRONOUNCED H5 THERMAL RDG IS EVIDENT STRETCHING FM THE NRN PLAINS
THRU NW MN AND INTO NW ONTARIO...WITH THE 00Z H5 TEMP UP TO -7C AT
INL...COMPARED TO THE -11C OBS AT APX CLOSER TO DEPARTING SHRTWV IN
THE CENTRAL LKS. THE COMBINATION OF THE ASSOCIATED MID LVL CAPPING
AND SUBSIDENCE RELATED TO DEEP LYR QVECTOR DVGC ACCOMPANYING THE
BLDG RDG IS RESULTING IN MOCLR SKIES OVER THE CWA EARLY THIS MRNG
DESPITE ADVECTION OF SOMEWHAT HIER LLVL MSTR WITH H85 DEWPTS UP TO
16C AT MPX IN THE SW FLOW ARND SFC HI PRES IN THE MID ATLANTIC
STATES. DESPITE THE MOCLR SKIES...THE STEADY SW FLOW IS RESULTING IN
ABV NORMAL TEMPS EARLY THIS MRNG...ESPECIALLY OVER THE W HALF OF UPR
MI IN THE DOWNSLOPE AREAS NEAR LK SUP...WHERE READINGS ARE HAVING A
HARD TIME FALLING BLO 70. BUT EVEN WARMER AIR IS TO THE W...WITH 00Z
H85 TEMPS RANGING FM 14C AT GRB AND APX TO 17C AT MPX...19C AT
INL...AND A TOASTY 25C AT BISMARCK. THERE IS ANOTHER SHRTWV SHIFTING
EWD THRU THE NRN PLAINS...BUT THE 00Z BISMARCK RAOB IS SO DRY THERE
IS NO PCPN OR EVEN ANY CLD COVER.
MAIN FCST CONCERNS IN THE SHORT TERM FOCUS ON TEMPS AND SMALL SHRA/
TS CHCS.
TODAY...UPR MI IS FCST TO REMAIN UNDER THE UPR RDG AXIS...WITH H5
THERMAL RDG/TEMPS ARND -7C NOTED ABOVE SHIFTING OVHD IN MID LVL
SUBSIDENCE REGIME. CONTINUED SW FLOW ARND STAGNANT SFC HI PRES IN
THE MID ATLANTIC IS FCST TO LIFT H85 TEMPS UP TO 17-18C OVER THE E
TO 18-19C OVER THE W BY 00Z WED. MIXING TO H8 ON GFS/NAM FCST SDNGS
YIELDS HI TEMPS REACHING TO ARND 90 AWAY FM THE COOLING INFLUENCE OF
LK MI...SO PREFER TO HEDGE TOWARD THE HI END OF GUIDANCE FOR MAX
TEMPS FCST. THIS SW FLOW WL ALSO ADVECT THE HIER LLVL MSTR SHOWN ON
THE 00Z MPX RAOB INTO THE UPR LKS...RESULTING IN A MORE HUMID AND
UNCOMFORTABLE DAY AS SFC DEWPTS RUN WELL INTO THE 60S. DESPITE THE
INCRSG HEAT/HUMIDITY THAT WL LIFT MUCAPE AOA 2000J/KG THIS AFTN PER
MODIFIED GFS/NAM FCST SDNGS FOR SFC T/TD 90/65...SUSPECT THE MID LVL
WARMTH/DRYNESS/STABILITY WL SUPPRESS CONVECTION. ONE POSITIVE FOR
SHRA/TS WOULD BE THE APRCH LATER THIS AFTN OF SHRTWV NOW MOVING THRU
THE NRN PLAINS...BUT CONSIDERING GFS/NAM MOS POPS AOB 10 PCT...
PRESENCE OF VERY WARM H5 AIR/SHARPER CAPPING...AND ABSENCE OF
APPRECIABLE LK BREEZE CNVGC WITH SUPPRESSION OF LK SUP BREEZE IN
SYNOPTIC SW FLOW...OPTED TO GO DRY FOR THE ENTIRE CWA TODAY.
TNGT...STEADY SW FLOW WITH H925 WINDS UP TO 30-35KTS UNDER
SHARPENING PRES GRADIENT BTWN MID ATLANTIC HI PRES AND APRCHG COLD
FNT IN MN ASSOCIATED WITH SHRTWV RIDING E IN THE ZONAL FLOW THRU
CANADA IS FCST TO LIFT H85 TEMPS AOA 20C OVER THE WRN CWA OVERNGT.
WL TEND AOA THE HI END OF GUIDANCE FOR MIN TEMPS...ESPECIALLY IN THE
DOWNSLOPE AREAS NEAR LK SUP OVER THE W HALF. CONCERNED THE ARRIVAL
OF SOME DEEP LYR QVECTOR CNVGC/STEEPENING LAPSE RATES WITH FALLING
H5 TEMPS TOWARD -10C IN ADVANCE OF THE FNT LATE TNGT MIGHT GENERATE
SOME SHRA/TS OVER AT LEAST THE NW HALF OF THE CWA. ALTHOUGH THE BULK
OF THE NUMERICAL MODELS SHOW A DRY FCST FOR THE CWA THRU 12Z WED...
OPTED TO RETAIN SOME SCHC POPS OVER THE MAINLY WRN/NCENTRAL LK SUP
SINCE THERE WL BE SOME DYNAMIC SUPPORT AND THE GFS AS WELL AS THE
LOCAL WRF/ARW MODELS DO GENERATE SOME PCPN.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 405 AM EDT TUE AUG 20 2013
NOT TOO MUCH HAS CHANGED SINCE 24 HOURS AGO...AND AM WELL IN
AGREEMENT WITH THE PREVIOUS SHIFT. STILL HAVE SOME
UNCERTAINTY...ESPECIALLY WITH SOME SPECIFIC ITEMS...BUT WILL TALK
ABOUT THAT IN MORE DETAIL BELOW.
FOR WED...A NRN STREAM TROUGH WILL SLIDE ACROSS THE CWA WED INTO WED
NIGHT...WHICH WILL BRING INCREASED CHANCES OF PRECIP FOR THAT
PERIOD. WITH 850MB TEMPS AROUND 20C AT PEAK HEATING WED
AFTERNOON...HIGH TEMPS AHEAD OF THE FRONT AND ASSOCIATED PRECIP AND
CLOUD COVER SHOULD BE ABLE TO GET INTO THE LOW 90S /AWAY FROM LAKE
MICHIGAN FROM MODERATING SW WINDS AND IMMEDIATE SHORES OF LAKE
SUPERIOR/. THE SW-NE ORIENTED COLD FRONT LOOKS TO MOVE INTO WRN
UPPER MI AROUND 18Z WED...WITH SOME VARIABILITY BETWEEN THE MODELS
/ECMWF AND GFS SHOWING THIS SOLUTION AND THE NAM AND GEM BEING
FASTER/. BY 00Z THU...MODELS SHOW THE COLD FRONT FROM ERN LAKE
SUPERIOR INTO SCENTRAL UPPER MI...WITH THE FRONT JUST E OF THE CWA
BY 06Z THU. SHOULD SEE CAPE VALUES OF 1500-2500J/KG AND POSSIBLY AS
HIGH AS 3000J/KG AHEAD OF THE FRONT. 0-6KM SHEAR LOOKS TO BE ON THE
LOW SIDE FOR ORGANIZED THUNDERSTORMS AT AROUND 20KTS...AND THAT IS
MOSTLY UNIDIRECTIONAL. STORM MODE SHOULD BE MULTICELL CLUSTERS AND
BEST THREAT FOR SEVERE WEATHER WILL BE MORE ISOLATED DAMAGING
WINDS...ESPECIALLY OVER THE SCENTRAL CWA WHERE DCAPE VALUES WILL BE
ENHANCED. HAIL THREAT WILL BE MORE MINIMAL DUE TO WEAK SHEAR AND THE
FREEZING LEVEL BEING AROUND 12KFT. WILL CONTINUE TO SHOW LIKELY POPS
OVER MUCH OF THE AREA TIMED CLOSE TO EXPECTED FROPA. WITH THE
UNCERTAINTY IN FRONTAL TIMING...HIGH TEMPS MAY BE MORE IN JEOPARDY
IF THE FRONT COMES THROUGH FASTER AND CONVECTIVE COVERAGE/INTENSITY
IS MORE UNCERTAIN.
BY LATE WED NIGHT...SHOULD SEE ALL PRECIP AND MOST CLOUDS CLEARED
OUT AS AS SFC HIGH MOVES IN FROM THE W...AND WITH 850MB TEMPS AROUND
12C BY 12Z THU...LOW TEMPS SHOULD BE ABLE TO QUICKLY FALL OFF TO
AROUND 50F OVER PARTS OF THE INTERIOR W.
WHILE A COUPLE OF UPPER SHORTWAVES MOVE THROUGH THU AND FRI...THE
SFC HIGH WILL BE DIRECTLY OVER THE CWA LATE THU INTO THU NIGHT...AND
WILL HAVE JUST MOVED E OFF THE CWA BY LATE FRI...SO IT WILL BE TOO
DRY FOR ANY PRECIP OVER THE CWA RESULTING FROM THE SHORTWAVES. 850MB
TEMPS COOL SOME MORE WITH CONTINUED NLY FLOW AND THE SHORTWAVE ON
THU TO AROUND 10-11C...RESULTING IN MUCH COOLER HIGH TEMPS IN THE
70S /OR POSSIBLY LOW 80S OVER FAR SCENTRAL UPPER MI/. FRI TEMPS LOOK
SIMILAR IF NOT A DEGREE OR TWO COOLER IN MOST LOCATIONS.
MORE UNCERTAIN ON LATER TIME FRAMES...BUT SOME PRECIP LOOKS POSSIBLE
LATE FRI NIGHT INTO EARLY SAT NIGHT AS A WARM FRONT/WAA MOVES INTO
THE CWA. MODELS AGREE ON BRINGING UPPER RIDGING ACROSS THE CWA SAT
AND SUN...RESULTING IN 850MB TEMPS INCREASING TO AROUND 20C BY 00Z
MON. THINK TEMPS MAY BE TOO LOW IN THE EXTENDED /SOMEWHAT FOR
SAT...BUT MORE SO FOR SUN/...BUT UNCERTAINTY RELATING TO PRECIP/CLOUDS
MAKES IT HARD TO JUSTIFY INCREASING TEMPS SIGNIFICANTLY. THINK THAT
CONSENSUS OF GUIDANCE WILL BE FAIRLY REPRESENTATIVE FOR SAT AND SUN.
MUCH DECREASED CONFIDENCE ON MON AS MODELS HAVE DIFFICULTY HANDLING
CONVECTION POSSIBILITIES NEAR/OVER THE CWA. WILL CONTINUE TO USE
CONSENSUS OF GUIDANCE FOR MON GIVEN THE LIMITED CONFIDENCE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 727 AM EDT TUE AUG 20 2013
EXPECT VFR CONDITIONS THRU THE FCST PERIOD AT ALL 3 TAF SITES WITH A
RELATIVELY DRY LLVL AIRMASS DOMINATING. WITH DAYTIME HEATING/
MIXING...A GUSTY SW WIND WL DVLP BY LATE MRNG. AFTER SUNSET...AN
INVERSION WL FORM AND RESULT IN LLWS WITH STRENGTHENING NOCTURNAL SW
LLJ UNDER SHARPENING PRES GRADIENT AHEAD OF APRCHG COLD FNT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 405 AM EDT TUE AUG 20 2013
OVERALL...EXPECT WINDS LESS THAN 20KT THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. ONE PERIOD OF STRONGER WINDS (GUSTS TO 20-25KT)
MAY OCCUR TONIGHT AS PRES GRADIENT TIGHTENS AHEAD OF APPROACHING
COLD FRONT...BUT HI OVERWATER STABILITY WITH INFLUX OF VERY WARM
AIRMASS WILL LIMIT THE INCREASE OF WIND SPEED NEAR THE COOLER LAKE
SURFACE. THE ARRIVAL OF MORE HUMID AIR MAY RESULT IN SOME FOG
FORMATION OVER THE COOLER LAKE WATERS...BUT RESTRICTED THE FOG
FORECAST TO AREAS WHERE SOME SHOWERS OR THUNDERSTORMS ARE EXPECTED.
ANY FOG WILL DISSIPATE WED AFTN/EVENING FOLLOWING A COLD FRONTAL
PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
406 AM EDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM EDT TUE AUG 20 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW REBOUNDING UPR RDG
INTO THE UPR GRT LKS ON THE SRN FLANK OF ZONAL FLOW OVER CANADA. A
PRONOUNCED H5 THERMAL RDG IS EVIDENT STRETCHING FM THE NRN PLAINS
THRU NW MN AND INTO NW ONTARIO...WITH THE 00Z H5 TEMP UP TO -7C AT
INL...COMPARED TO THE -11C OBS AT APX CLOSER TO DEPARTING SHRTWV IN
THE CENTRAL LKS. THE COMBINATION OF THE ASSOCIATED MID LVL CAPPING
AND SUBSIDENCE RELATED TO DEEP LYR QVECTOR DVGC ACCOMPANYING THE
BLDG RDG IS RESULTING IN MOCLR SKIES OVER THE CWA EARLY THIS MRNG
DESPITE ADVECTION OF SOMEWHAT HIER LLVL MSTR WITH H85 DEWPTS UP TO
16C AT MPX IN THE SW FLOW ARND SFC HI PRES IN THE MID ATLANTIC
STATES. DESPITE THE MOCLR SKIES...THE STEADY SW FLOW IS RESULTING IN
ABV NORMAL TEMPS EARLY THIS MRNG...ESPECIALLY OVER THE W HALF OF UPR
MI IN THE DOWNSLOPE AREAS NEAR LK SUP...WHERE READINGS ARE HAVING A
HARD TIME FALLING BLO 70. BUT EVEN WARMER AIR IS TO THE W...WITH 00Z
H85 TEMPS RANGING FM 14C AT GRB AND APX TO 17C AT MPX...19C AT
INL...AND A TOASTY 25C AT BISMARCK. THERE IS ANOTHER SHRTWV SHIFTING
EWD THRU THE NRN PLAINS...BUT THE 00Z BISMARCK RAOB IS SO DRY THERE
IS NO PCPN OR EVEN ANY CLD COVER.
MAIN FCST CONCERNS IN THE SHORT TERM FOCUS ON TEMPS AND SMALL SHRA/
TS CHCS.
TODAY...UPR MI IS FCST TO REMAIN UNDER THE UPR RDG AXIS...WITH H5
THERMAL RDG/TEMPS ARND -7C NOTED ABOVE SHIFTING OVHD IN MID LVL
SUBSIDENCE REGIME. CONTINUED SW FLOW ARND STAGNANT SFC HI PRES IN
THE MID ATLANTIC IS FCST TO LIFT H85 TEMPS UP TO 17-18C OVER THE E
TO 18-19C OVER THE W BY 00Z WED. MIXING TO H8 ON GFS/NAM FCST SDNGS
YIELDS HI TEMPS REACHING TO ARND 90 AWAY FM THE COOLING INFLUENCE OF
LK MI...SO PREFER TO HEDGE TOWARD THE HI END OF GUIDANCE FOR MAX
TEMPS FCST. THIS SW FLOW WL ALSO ADVECT THE HIER LLVL MSTR SHOWN ON
THE 00Z MPX RAOB INTO THE UPR LKS...RESULTING IN A MORE HUMID AND
UNCOMFORTABLE DAY AS SFC DEWPTS RUN WELL INTO THE 60S. DESPITE THE
INCRSG HEAT/HUMIDITY THAT WL LIFT MUCAPE AOA 2000J/KG THIS AFTN PER
MODIFIED GFS/NAM FCST SDNGS FOR SFC T/TD 90/65...SUSPECT THE MID LVL
WARMTH/DRYNESS/STABILITY WL SUPPRESS CONVECTION. ONE POSITIVE FOR
SHRA/TS WOULD BE THE APRCH LATER THIS AFTN OF SHRTWV NOW MOVING THRU
THE NRN PLAINS...BUT CONSIDERING GFS/NAM MOS POPS AOB 10 PCT...
PRESENCE OF VERY WARM H5 AIR/SHARPER CAPPING...AND ABSENCE OF
APPRECIABLE LK BREEZE CNVGC WITH SUPPRESSION OF LK SUP BREEZE IN
SYNOPTIC SW FLOW...OPTED TO GO DRY FOR THE ENTIRE CWA TODAY.
TNGT...STEADY SW FLOW WITH H925 WINDS UP TO 30-35KTS UNDER
SHARPENING PRES GRADIENT BTWN MID ATLANTIC HI PRES AND APRCHG COLD
FNT IN MN ASSOCIATED WITH SHRTWV RIDING E IN THE ZONAL FLOW THRU
CANADA IS FCST TO LIFT H85 TEMPS AOA 20C OVER THE WRN CWA OVERNGT.
WL TEND AOA THE HI END OF GUIDANCE FOR MIN TEMPS...ESPECIALLY IN THE
DOWNSLOPE AREAS NEAR LK SUP OVER THE W HALF. CONCERNED THE ARRIVAL
OF SOME DEEP LYR QVECTOR CNVGC/STEEPENING LAPSE RATES WITH FALLING
H5 TEMPS TOWARD -10C IN ADVANCE OF THE FNT LATE TNGT MIGHT GENERATE
SOME SHRA/TS OVER AT LEAST THE NW HALF OF THE CWA. ALTHOUGH THE BULK
OF THE NUMERICAL MODELS SHOW A DRY FCST FOR THE CWA THRU 12Z WED...
OPTED TO RETAIN SOME SCHC POPS OVER THE MAINLY WRN/NCENTRAL LK SUP
SINCE THERE WL BE SOME DYNAMIC SUPPORT AND THE GFS AS WELL AS THE
LOCAL WRF/ARW MODELS DO GENERATE SOME PCPN.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 405 AM EDT TUE AUG 20 2013
NOT TOO MUCH HAS CHANGED SINCE 24 HOURS AGO...AND AM WELL IN
AGREEMENT WITH THE PREVIOUS SHIFT. STILL HAVE SOME
UNCERTAINTY...ESPECIALLY WITH SOME SPECIFIC ITEMS...BUT WILL TALK
ABOUT THAT IN MORE DETAIL BELOW.
FOR WED...A NRN STREAM TROUGH WILL SLIDE ACROSS THE CWA WED INTO WED
NIGHT...WHICH WILL BRING INCREASED CHANCES OF PRECIP FOR THAT
PERIOD. WITH 850MB TEMPS AROUND 20C AT PEAK HEATING WED
AFTERNOON...HIGH TEMPS AHEAD OF THE FRONT AND ASSOCIATED PRECIP AND
CLOUD COVER SHOULD BE ABLE TO GET INTO THE LOW 90S /AWAY FROM LAKE
MICHIGAN FROM MODERATING SW WINDS AND IMMEDIATE SHORES OF LAKE
SUPERIOR/. THE SW-NE ORIENTED COLD FRONT LOOKS TO MOVE INTO WRN
UPPER MI AROUND 18Z WED...WITH SOME VARIABILITY BETWEEN THE MODELS
/ECMWF AND GFS SHOWING THIS SOLUTION AND THE NAM AND GEM BEING
FASTER/. BY 00Z THU...MODELS SHOW THE COLD FRONT FROM ERN LAKE
SUPERIOR INTO SCENTRAL UPPER MI...WITH THE FRONT JUST E OF THE CWA
BY 06Z THU. SHOULD SEE CAPE VALUES OF 1500-2500J/KG AND POSSIBLY AS
HIGH AS 3000J/KG AHEAD OF THE FRONT. 0-6KM SHEAR LOOKS TO BE ON THE
LOW SIDE FOR ORGANIZED THUNDERSTORMS AT AROUND 20KTS...AND THAT IS
MOSTLY UNIDIRECTIONAL. STORM MODE SHOULD BE MULTICELL CLUSTERS AND
BEST THREAT FOR SEVERE WEATHER WILL BE MORE ISOLATED DAMAGING
WINDS...ESPECIALLY OVER THE SCENTRAL CWA WHERE DCAPE VALUES WILL BE
ENHANCED. HAIL THREAT WILL BE MORE MINIMAL DUE TO WEAK SHEAR AND THE
FREEZING LEVEL BEING AROUND 12KFT. WILL CONTINUE TO SHOW LIKELY POPS
OVER MUCH OF THE AREA TIMED CLOSE TO EXPECTED FROPA. WITH THE
UNCERTAINTY IN FRONTAL TIMING...HIGH TEMPS MAY BE MORE IN JEOPARDY
IF THE FRONT COMES THROUGH FASTER AND CONVECTIVE COVERAGE/INTENSITY
IS MORE UNCERTAIN.
BY LATE WED NIGHT...SHOULD SEE ALL PRECIP AND MOST CLOUDS CLEARED
OUT AS AS SFC HIGH MOVES IN FROM THE W...AND WITH 850MB TEMPS AROUND
12C BY 12Z THU...LOW TEMPS SHOULD BE ABLE TO QUICKLY FALL OFF TO
AROUND 50F OVER PARTS OF THE INTERIOR W.
WHILE A COUPLE OF UPPER SHORTWAVES MOVE THROUGH THU AND FRI...THE
SFC HIGH WILL BE DIRECTLY OVER THE CWA LATE THU INTO THU NIGHT...AND
WILL HAVE JUST MOVED E OFF THE CWA BY LATE FRI...SO IT WILL BE TOO
DRY FOR ANY PRECIP OVER THE CWA RESULTING FROM THE SHORTWAVES. 850MB
TEMPS COOL SOME MORE WITH CONTINUED NLY FLOW AND THE SHORTWAVE ON
THU TO AROUND 10-11C...RESULTING IN MUCH COOLER HIGH TEMPS IN THE
70S /OR POSSIBLY LOW 80S OVER FAR SCENTRAL UPPER MI/. FRI TEMPS LOOK
SIMILAR IF NOT A DEGREE OR TWO COOLER IN MOST LOCATIONS.
MORE UNCERTAIN ON LATER TIME FRAMES...BUT SOME PRECIP LOOKS POSSIBLE
LATE FRI NIGHT INTO EARLY SAT NIGHT AS A WARM FRONT/WAA MOVES INTO
THE CWA. MODELS AGREE ON BRINGING UPPER RIDGING ACROSS THE CWA SAT
AND SUN...RESULTING IN 850MB TEMPS INCREASING TO AROUND 20C BY 00Z
MON. THINK TEMPS MAY BE TOO LOW IN THE EXTENDED /SOMEWHAT FOR
SAT...BUT MORE SO FOR SUN/...BUT UNCERTAINTY RELATING TO PRECIP/CLOUDS
MAKES IT HARD TO JUSTIFY INCREASING TEMPS SIGNIFICANTLY. THINK THAT
CONSENSUS OF GUIDANCE WILL BE FAIRLY REPRESENTATIVE FOR SAT AND SUN.
MUCH DECREASED CONFIDENCE ON MON AS MODELS HAVE DIFFICULTY HANDLING
CONVECTION POSSIBILITIES NEAR/OVER THE CWA. WILL CONTINUE TO USE
CONSENSUS OF GUIDANCE FOR MON GIVEN THE LIMITED CONFIDENCE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 122 AM EDT TUE AUG 20 2013
WITH RELATIVELY DRY LOW-LEVELS PERSISTING...VFR CONDITIONS ARE
EXPECTED THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. AS WITH RECENT
NIGHTS...INCREASING SW WINDS TONIGHT ABOVE NOCTURNAL INVERSION WILL
APPROACH LLWS CRITERIA. DAYTIME MIXING WILL RESULT IN SW WIND GUSTS
BETWEEN 15 AND 20 KNOTS ON TUESDAY.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 405 AM EDT TUE AUG 20 2013
OVERALL...EXPECT WINDS LESS THAN 20KT THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. ONE PERIOD OF STRONGER WINDS (GUSTS TO 20-25KT)
MAY OCCUR TONIGHT AS PRES GRADIENT TIGHTENS AHEAD OF APPROACHING
COLD FRONT...BUT HI OVERWATER STABILITY WITH INFLUX OF VERY WARM
AIRMASS WILL LIMIT THE INCREASE OF WIND SPEED NEAR THE COOLER LAKE
SURFACE. THE ARRIVAL OF MORE HUMID AIR MAY RESULT IN SOME FOG
FORMATION OVER THE COOLER LAKE WATERS...BUT RESTRICTED THE FOG
FORECAST TO AREAS WHERE SOME SHOWERS OR THUNDERSTORMS ARE EXPECTED.
ANY FOG WILL DISSIPATE WED AFTN/EVENING FOLLOWING A COLD FRONTAL
PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...VOSS
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
123 AM EDT TUE AUG 20 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 422 PM EDT MON AUG 19 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW ACROSS MUCH OF
SRN CANADA. SHORTWAVE TROF THAT WAS OVER MT/SRN SASKATCHEWAN 24HRS
AGO IS NOW OVER THE UPPER LAKES THOUGH MUCH OF THE ENERGY APPEARS TO
BE SETTLING SSE INTO THE WEAKENING REMNANT OF THE TROF THAT HAS BEEN
OVER THE LOWER MISSISSIPPI VALLEY THE LAST FEW DAYS. WAVE PRODUCED A
CLUSTER OF SHRA/TSRA OVER WRN LAKE SUPERIOR THIS MORNING. THE SHRA
RAPIDLY DIMINISHED AS THEY APPROACHED WRN UPPER MI AND DISSIPATED
SOON AFTER REACHING THAT AREA. SO...FAR NO NEW SHRA/TSRA HAVE
DEVELOPED WITH DAYTIME HEATING.
LATEST SPC MESOANALYSIS SHOWS MLCAPE OF 500-1000J/KG OVER ROUGHLY
THE W HALF OF UPPER MI. VIS SATELLITE IMAGERY SHOWS CU DEVELOPING
OVER THE LAST COUPLE OF HRS...AND LATEST OBS ALONG THE SHORE
INDICATE LAKE BREEZE JUST BEGINNING TO DEVELOP OFF LAKE SUPERIOR.
PERHAPS A FEW SHRA/TSRA MAY YET DEVELOP OVER THE NEXT COUPLE OF HRS
AS LAKE BREEZE MAKES SOME INLAND PROGRESS. SINCE LATEST HIGH RES
RAPID REFRESH MODEL STILL GENERATES SOME CONVECTION OVER THE NCNTRL
LATE THIS AFTN...WILL HOLD ONTO SCHC POPS FOR THE NEXT SEVERAL HRS.
IF ANY SHRA/TSRA DO DEVELOP...THEY WILL DISSIPATE WITH LOSS OF
DAYTIME HEATING...ESPECIALLY SINCE HEIGHTS ARE IN THE PROCESS OF
STEADILY RISING AND DEEP LAYER QVECTOR DIVERGENCE IS DEVELOPING.
THERE IS SOME THETA-E ADVECTION OVERNIGHT...AND THE GEM SUGGESTS
SOME ISOLD CONVECTION LATE TONIGHT/TUE MORNING AT LEADING EDGE OF
THETA-E AXIS APPROACHING WRN UPPER MI. HOWEVER...WITH 850MB WINDS
ANTICYCLONIC AND NOT MUCH OF A LOW-LEVEL JET...POTENTIAL OF ANY
ISOLD CONVECTION LATE SEEMS VERY UNLIKELY. WILL CARRY DRY FCST THRU
THE OVERNIGHT. ALTHOUGH SKIES WILL TURN MOSTLY CLEAR...A LIGHT BUT
STEADY SW WIND AND INCREASED COLUMN MOISTURE WILL WORK TO LIMIT THE
DIURNAL TEMP FALL. UNDER S TO SW WINDS...THE HIGHEST MIN TEMPS WILL
BE IN THE DOWNSLOPE AREAS NEAR LAKE SUPERIOR OVER THE W HALF. EXPECT
MINS IN THE MID 60S THERE. INLAND...MID 50S TO AROUND 60F SHOULD BE
THE RULE.
ON TUE...PRES GRADIENT TIGHTENS A BIT BTWN SFC HIGH OVER THE MID
ATLANTIC STATES AND A LOW PRES TROF MOVING ACROSS THE NRN
PLAINS/SCNTRL CANADA. STRENGTHENING SW FLOW WILL BRING AN INCREASE
IN LOW-LEVEL DWPTS TUE...RESULTING IN A MUCH MORE UNCOMFORTABLE DAY.
MIXING TOWARD 800MB ON FCST SOUNDINGS SUGGESTS MAX TEMPS EASILY INTO
THE MID/UPPER 80S. STRONGER SW WINDS WILL PREVENT LAKE BREEZE
DEVELOPMENT OFF LAKE SUPERIOR AND SHOULD LEAD TO SOME OF THE
WARMEST READINGS IN THE DOWNSLOPE AREAS NEAR THE LAKE. EXPECT SOME
LOCATIONS TO REACH OR JUST EXCEED 90F. S/SW WINDS WILL KEEP
CONDITIONS COOLER NEAR LAKE MICHIGAN. COMBINATION OF TEMPS WELL INTO
THE 80S AND HIGHER DWPTS INTO THE 60S WILL MAKE TUE THE MOST
UNCOMFORTABLE DAY SINCE THE HOT WEATHER STRETCH IN MID JULY. NAM
SHOWS MLCAPE INCREASING TO 2000-3000J/KG TUE AFTN WHILE THE GFS IS
LOWER IN THE 1000-2000J/KG RANGE. LACK OF LAKE BREEEZE DEVELOPMENT
OFF LAKE SUPERIOR WILL BE ONE MISSING FORCING MECHANISM TO TRIGGER
CONVECTION. SINCE THERE ARE HINTS OF A SUBTLE SHORTWAVE MOVING
TOWARD THE UPPER LAKES...OPTED TO MAINTAIN SCHC POPS OVER PORTIONS
OF CNTRL UPPER MI WHERE THERE IS SOME LOW-LEVEL CONVERGENCE AS A
RESULT OF LAKE MICHIGAN LAKE BREEZE COMPONENT. IN THE ABSENCE OF ANY
SHORTWAVE...TUE WILL LIKELY END UP DRY ACROSS THE BOARD.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 422 PM EDT MON AUG 19 2013
NORTHERN STREAM UPPER TROUGH WILL SLIDE THROUGH THE AREA DURING
THE FIRST PART OF THE LONG TERM PERIOD AND LEAD TO A DECENT CHANCE
OF RAIN OVER THE AREA WEDNESDAY.
FIRST FOR TUESDAY NIGHT...THERE MAY BE SOME SHOWERS/THUNDERSTORMS
OVER LAKE SUPERIOR ON AHEAD OF THE COLD FRONT. THIS A CONTINUATION
OF THE CONVECTION THAT DEVELOPS IN SOUTHWEST ONTARIO AND NORTHEAST
MINNESOTA FROM THE AFTERNOON AND A WEAK SHORTWAVE MOVING EAST
ACROSS LAKE SUPERIOR. IN ADDITION...THIS IS ALSO THE AREA OF THE
STRENGTHENING LOW LEVEL JET AND 850-700MB THERMAL RIDGE. WITH STORM
MOTIONS TO THE EAST...WOULD THINK ISLE ROYALE AND NORTHERN LAKE
SUPERIOR WOULD HAVE THE BEST SHOT OF SEEING PRECIPITATION...BUT IT
COULD BRUSH THE KEWEENAW PENINSULA.
ON WEDNESDAY...THE MAIN SHORTWAVE WILL BE MOVING THROUGH SOUTHWEST
ONTARIO AND BE DISCONNECTED FROM THE COLD FRONT MOVING EAST ACROSS
WESTERN LAKE SUPERIOR ON WEDNESDAY MORNING. BUT...THERE ARE HINTS
THAT A SECOND WEAKER WAVE WILL BE SLIDING EAST ACROSS NORTHERN
WISCONSIN AND WESTERN UPPER MICHIGAN IN THE AFTERNOON. IF THIS
OCCURS...IT WOULD ASSIST WITH CONVECTIVE DEVELOPMENT AS THE COLD
FRONT MOVES THROUGH WESTERN/CENTRAL U.P. DURING THE DAY WEDNESDAY.
MODELS SEEM TO HAVE SPED IT UP A TOUCH WITH IT MOVING THROUGH THE
WESTERN U.P. IN THE LATE MORNING OR EARLY AFTERNOON AND THEN THE
CENTRAL U.P. IN THE MID AFTERNOON HOURS. IT THEN EXITS THE AREA
OVER LAKE MICHIGAN DURING THE EVENING. WITH THE WARM...HUMID
AIRMASS...INSTABILITY WILL BE PRETTY GOOD FOR U.P. STANDARDS (MLCAPE
VALUES OF 1500-3000 J/KG DEPENDING ON THE MODEL) WHICH ARE AIDED BY
STEEP MID LEVEL LAPSE RATES (AROUND 7-7.5C/KM FROM 850-700MB). THIS
HELPS BOOST HAIL CAPE VALUES TOWARDS 800 J/KG...BUT WITH FREEZING
LEVELS AROUND 12KFT...IT MAY COUNTERACT THE HAIL POTENTIAL. 0-6KM
AND EFFECTIVE SHEAR VALUES ARE MARGINAL FOR THUNDERSTORM
ORGANIZATION (ONLY AROUND 20-25KTS) AND FAIRLY UNIDIRECTIONAL. 09Z
SREF RUN AGREES WITH THAT BASIC IDEA AND ONLY HAS 50 PERCENT PROBS
FOR EFFECTIVE SHEAR OVER 30KTS. BUT WITH THE COLD FRONT...WOULD
EXPECT SOME CLUSTERS OR LINE OF STORMS TO FORM. STORM MOTION AND
MOVEMENT OF THE COLD FRONT WOULD SUPPORT AN EAST TO SOUTHEAST
MOVEMENT OF THE THUNDERSTORMS. FINALLY...THINK THERE WILL BE SOME
WIND THREAT DUE TO DCAPE VALUES PEAKING OVER THE SOUTH CENTRAL WHERE
THERE WILL BE LESS OF AN INFLUENCE OF CLOUDS TO AID
DESTABILIZATION. THUS...HAVE TRENDED SOME LOCATIONS UP TO
SHOWERS/THUNDERSTORMS LIKELY OVER THE CENTRAL AND WEST-CENTRAL IN
THE AFTERNOON. SPC HAS WESTERN/CENTRAL PORTIONS OF THE U.P. IN A
SLIGHT RISK AND THAT SEEMS REASONABLE AT THIS POINT ALTHOUGH THE
LIMITED SHEAR LEAVES SOME CONCERN FOR WIDESPREAD SEVERE WEATHER.
THE WARM AIR AHEAD OF THE COLD FRONT WILL PRODUCE ANOTHER WARM
DAY...ESPECIALLY OVER THE CENTRAL/EAST (HIGHS IN UPPER 80S OR
LOWER 90S). THE WEST MAY BE LIMITED BY MID CLOUDS MOVING IN AHEAD OF
THE COLD FRONT AND HAVE HIGHS IN THE 80S THERE.
AS THE UPPER TROUGH SHIFT EAST ON THURSDAY...HIGH PRESSURE WILL
BUILD OVER THE AREA WHILE AN UPPER RIDGE BUILD OVER THE NORTH
CENTRAL CONUS AND CENTRAL CANADA. WITH THIS HIGH IN PLACE...EXPECT
ANOTHER PERIOD OF DRIER WEATHER INTO THE FIRST PART OF THE WEEKEND.
A SECONDARY SHORTWAVE MOVES THROUGH ON THURSDAY...BUT WITH THE DRY
ATMOSPHERE...DON/T EXPECT MUCH MORE THAN PASSING MID CLOUDS.
TEMPERATURES DURING THE LONG TERM PERIOD WILL BE COOLEST ON
THURSDAY/FRIDAY BEHIND THE COLD FRONT (HIGHS IN THE
70S)...BUT THEN AS THE HIGH SHIFTS EAST SATURDAY...SOUTH-SOUTHWEST
LOW LEVEL FLOW WILL ALLOW TEMPERATURES TO WARM BACK ABOVE NORMAL
FOR THE WEEKEND (HIGHS AROUND 80S...ALTHOUGH THE LATEST ECMWF IS
SHOWING VALUES NEAR 90).
MODELS DIFFER SOMEWHAT FOR SATURDAY INTO MONDAY...DUE TO CONVECTION
FIRING OR NOT FIRING ALONG THE REMNANTS OF THE COLD FRONT
STRETCHING FROM SOUTHERN MINNESOTA THROUGH THE OHIO RIVER VALLEY.
THE ECMWF HAS BEEN SHOWING THIS FRONT SLOWLY PUSHING NORTH AS A
WARM FRONT THROUGH THE WEEKEND...WHICH WOULD GIVE BETTER CHANCES
FOR PRECIPITATION FOR THE END OF THE WEEKEND INTO THE BEGINNING OF
NEXT WEEK. THE GFS ON THE OTHERHAND AS BEEN SHOWING A STRONGER HIGH
LINGERING OVER THE AREA AND KEEPING THE BROAD AREA OF LOW PRESSURE
FOCUSED IN THE DAKOTAS (SIMILAR TO WHAT WE HAVE EXPERIENCED OVER
THE LAST COUPLE OF DAYS). BOTH MODELS HAVE BEEN VARYING ON THEIR
SOLUTIONS OVER THE LAST COUPLE OF DAYS...SO CONFIDENCE IS LIMITED
THIS FAR OUT. THEREFORE...WILL FOLLOW A GENERAL CONSENSUS WITH
CHANCE OR SLIGHT CHANCE POPS FOR THE WEEKEND INTO EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 122 AM EDT TUE AUG 20 2013
WITH RELATIVELY DRY LOW-LEVELS PERSISTING...VFR CONDITIONS ARE
EXPECTED THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. AS WITH RECENT
NIGHTS...INCREASING SW WINDS TONIGHT ABOVE NOCTURNAL INVERSION WILL
APPROACH LLWS CRITERIA. DAYTIME MIXING WILL RESULT IN SW WIND GUSTS
BETWEEN 15 AND 20 KNOTS ON TUESDAY.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 422 PM EDT MON AUG 19 2013
OVERALL...EXPECT WINDS LESS THAN 20KT THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. ONE PERIOD OF STRONGER WINDS (GUSTS TO 20-25KT)
MAY OCCUR TUE NIGHT AS PRES GRADIENT TIGHTENS DUE TO APPROACHING
COLD FRONT. THE ARRIVAL OF MORE HUMID AIR TUE/WED MAY RESULT IN SOME
FOG FORMATION OVER THE COOLER LAKE WATERS. HOWEVER...FOG WILL BE
MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS OCCUR OVER THE LAKE. ANY
FOG WILL DISSIPATE WED AFTN/EVENING FOLLOWING A COLD FRONTAL PASSAGE
AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS JACKSON MS
917 PM CDT WED AUG 21 2013
.UPDATE...NO MAJOR CHANGES WERE MADE TO THE FORECAST THIS EVENING.
TODAY`S ROUND OF CONVECTION HAS BEGUN TO WIND DOWN IN COVERAGE/
INTENSITY OVER THE LAST COUPLE HOURS...THOUGH SOME CONVECTION
PERSISTS ALONG I-20 IN EASTERN MISSISSIPPI. LAST NIGHT IT WAS TO THE
WEST OF FOREST...THIS EVENING IT IS TO THE EAST OF FOREST AND INTO
THE MERIDIAN AREA. OVERALL COVERAGE WILL CONTINUE TO DIMINISH OVER
THE NEXT FEW HOURS AS INSTABILITY GRADUALLY WANES. WITH A RATHER
MOIST AIR MASS (PWATS REMAINING AROUND TWO INCHES) REMAINING IN
PLACE ACROSS THE CWA...ISOLATED CONVECTION CANNOT BE ENTIRELY RULED
OUT OVERNIGHT. THIS MOISTURE WILL AID IN THE DEVELOPMENT OF ANOTHER
ROUND OF LOW STRATUS AND EVEN SOME PATCHY FOG ONCE AGAIN LATE
TONIGHT AND EARLY THURSDAY MORNING. THE EXISTING SKY GRIDS ALREADY
DEPICTED CONSIDERABLE CLOUDINESS BUT THE WX GRIDS WERE UPDATED TO
INCLUDE MENTION OF SOME PATCHY FOG AS WELL. HOURLY TEMP/DEWPOINT
GRIDS WERE ALSO ADJUSTED TO MATCH CURRENT OB TRENDS. /DL/
&&
.AVIATION...CONVECTION THIS EVENING AVOIDING ANY TAF SITES AS
PRIMARILY OCCURRING IN PINE BELT REGION N OF KHBG...AND OVER EAST
CENTRAL LA. EXPECT CONVECTION WILL DIMINISH THIS EVENING...WITH MAIN
CONCERN AS LAST SEVERAL NIGHTS DEVELOPMENT OF LOW STRATUS. NAM/GFS
IMPLY BEST LOW LEVEL MOISTURE HANGING ALONG/SE OF NATCHEZ TRACE...AND
THIS IS WHERE LAMP AND HRRR SHOW DEVELOPMENT OF LIFR CONDITIONS DUE
TO CIGS AND BR. CONTINUED TREND OF PREVIOUS TAF PACKAGE TO HIT THESE
SORTS OF CONDITIONS EXCEPT FOR DELTA SITES. EXPECT IMPROVING
CONDITIONS THROUGH MORNING WITH VFR CONDITIONS BY MIDDAY. SCATTERED
CONVECTION CAN BE EXPECTED AGAIN THU AFTERNOON...BUT RIGHT NOW
THINKING A BIT LESS COVERAGE THAN LAST COUPLE OF DAYS AND
PARTICULARLY FOCUSED OVER SOUTHERN AREAS. DID NOT INCLUDE ANY TSRA
IN TAFS AT THIS POINT. /AEG/
&&
.DISCUSSION... /ISSUED AT 347 PM CDT WED AUG 21 2013/
SHORT TERM...THROUGH FRIDAY NIGHT...AMPLE MOISTURE WILL CONTINUE TO
FLOW UP ACROSS THE FORECAST AREA THROUGH THE PERIOD. SHOWERS AND
STORMS WILL BE A BIT MORE SCARCE ON THURSDAY AS THE TROUGH DEPARTS
AND MID/UPPER LEVEL RIDGING BUILDS INTO THE FORECAST AREA FROM THE
WEST. AS RAIN CHANCES LESSEN...TEMPERATURES WILL INCREASE A FEW
DEGREES OR SO AS HIGHS THURSDAY AFTERNOON CLIMB INTO THE LOW TO MID
90S. OVERNIGHT LOWS WILL AGAIN FALL DOWN AROUND 70.
LOOKING TO FRIDAY...BEST CHANCES FOR PRECIP WILL BE ACROSS THE
SOUTHERN CWA WHERE THE BETTER MOISTURE WILL EXIST. RAIN CHANCES WILL
BE LESS TO THE NORTH THANKS TO MID AND UPPER LEVEL RIDGING. HIGHS ON
FRIDAY WILL ONCE AGAIN CLIMB INTO THE LOW TO MID 90S...WITH LOWS
FRIDAY NIGHT AROUND 70. /27/19/
LONG TERM...SATURDAY INTO THE MIDDLE OF NEXT WEEK...NOT TO MANY BIG
SURPRISES THIS GO ROUND IN THE LONG RANGE PORTION OF THE FORECAST AS
MODELS GENERALLY REMAIN IN GOOD AGREEMENT AND FAIRLY CONSISTENT FROM
RUN-TO-RUN.
THROUGH THE WEEKEND EXPECT A RATHER STOUT UPPER LEVEL SUBTROPICAL
RIDGE CENTER TO MIGRATE SLOWLY EAST FROM THE SOUTHERN PLAINS TO THE
MID MISSISSIPPI VALLEY. DURING THIS TIME THE SOUTHEAST AND SOUTHERN
PERIPHERY OF THE RIDGE WILL HAVE GRADUALLY INCREASING SUBSIDENT
IMPACT ON NORTHERN ZONES (ESPECIALLY UP IN THE ARKLAMISS DELTA).
THIS WILL RESULT IN RELATIVELY SMALL DIURNALLY-DRIVEN RAIN CHANCES
UP IN THE ARKLAMISS DELTA...TRANSITIONING TO DECENT CHANCES OF
PRECIP IN THE MAINLY THE AFTERNOON AND EARLY EVENING SOUTH OF I-20.
ACTUALLY SOME SUGGESTION OF LINGERING JET LEVEL TROUGH IN SOUTHERN
ZONES...COMBINED WITH HIGH MOISTURE (> 2 IN PW VALUES) AND H850
CONVERGENCE...WHICH COULD RESULT IN LOCALLY HEAVY PRECIP AMOUNTS
THROUGH THIS PRESCRIBED PERIOD. DURING THIS TIME ANY FLOODING
PROBLEMS WILL BE EXTREMELY ISOLATED AND THUS NOT REALLY WORTH
MENTION IN THE HWO. FRIDAY THROUGH SUNDAY HEAT AND HUMIDITY WILL BE
LIKELY BE TEMPERED BY CLOUDS AND PRECIP TO LEVEL LESS THAN MEXMOS
EXPECTATIONS ALONG AND SOUTHEAST OF THE NATCHEZ TRACE
CORRIDOR...WHILE FURTHER NORTHWEST PEAK HEAT INDEX VALUES ASSOCIATED
WITH TEMPS WELL UP IN THE 90S COULD POSSIBLY REACH THE LOW 100S.
EARLY NEXT WEEK THE UPPER LEVEL RIDGE LOOKS TO REMAIN SOMEWHAT
STATIONARY...ALTHOUGH PERHAPS THE CENTER WILL DROP A LITTLE SOUTH
DOWN THE AXIS OF THE MISSISSIPPI RIVER VALLEY. THIS WILL PROMOTE
MORE WIDESPREAD SUBSIDENCE AND DIVERGENCE AT THE SURFACE AND THUS
LESS RAIN CHANCES IN ALL AREAS. MAIN CHANCES FOR AFTERNOON STORMS
THEN WILL BE OVER FAR SOUTHERN PORTIONS OF THE CWA.
FORTUNATELY...MODELS GENERALLY AGREE THAT LOW LEVEL FLOW VECTORS
EARLY NEXT WEEK WILL BE PREDOMINANTLY FROM THE SOUTHEAST OR
EAST...WHICH CLIMATOLOGICALLY DOES NOT PROMOTE A GREAT DEAL OF HEAT.
HOWEVER...LOCATIONS UP IN THE ARKLAMISS DELTA COULD STILL HOLD ONTO
HIGHS AT LEAST IN THE MID 90S.
IF THIS STAGNANT RIDGE DOES NOT BREAK LATER NEXT WEEK WE COULD BE
LOOKING AT A PROLONGED STRETCH OF BELOW AVERAGE RAINFALL AND A
POSSIBLE LATE-SEASON HEAT WAVE. HOWEVER...IT IS TOO EARLY TO HAVE A
GREAT DEAL OF CONFIDENCE WHETHER OR NOT THIS EVOLUTION WILL COME TO
PASS...SO STAY TUNED. /BB/
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
DL/AEG/27/19/BB
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
136 PM CDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT TUE AUG 20 2013
TODAY AND TONIGHT...850MB WINDS CONTINUE FROM THE SOUTH WITH A
SLIGHT SOUTHWEST COMPONENT. SPEEDS INCREASE TO AROUND 25 KTS
SUPPORTING 15 TO 25 MPH SFC WIND SPEEDS. A DRYLINE BULGE SHOULD
DEVELOP ACROSS WRN NEB AND THE SANDHILLS SUPPORTING DEEPER
MIXING. SOME OF GUIDANCE SUGGESTS LOW 100S FOR HIGHS. THE PROBLEM
AREA IS NRN NEB AND VALENTINE WHERE HOT DRY AIR WILL BLOW NORTH
OFF THE SANDHILLS. IF THE SANDHILLS ARE DRY THEN THIS AREA WILL
RISE ABOVE 100.
FOR NOW TEMPS ARE A BLEND OF TRIED AND TRUE GUIDANCE FOR HIGHS IN
THE 90S TO 100. WITH H700MB TEMPS RISING TOWARD 16C THIS AFTN
ACROSS WRN NEB THERE COULD BE SOME LOW 100S BUT WE WOULD LIKE TO
SEE A MORE SWRLY COMPONENT TO THE 850 MB WINDS AND 700MB WINDS
DUE WEST VS THE RAP FCSTING SOUTHWEST WINDS AT 700MB.
ISOLATED TSTMS ARE POSSIBLE THIS AFTN ACROSS NWRN NEB AS A COLD
FRONT DROPS IN. A SLIGHT COOLING ALOFT TONIGHT MIGHT ALLOW A FEW
STORMS TO FORM FARTHER EAST ACROSS NRN NEB. OTHERWISE THE HEAT
CONTINUES TODAY WITH DEW POINTS IN THE UPPER 60S EAST OF HIGHWAY
83. THE DRYLINE BULGE SHOULD REACH TO HIGHWAY 83 THIS AFTN AND
THEN RETREAT WEST THIS EVENING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 341 AM CDT TUE AUG 20 2013
SUMMER LIKE WEATHER THROUGH MUCH OF THE MID TO LONG RANGE
FORECAST. UPPER LEVEL RIDGE WILL CONTINUE TO MIGRATE EAST AND
BECOME CENTERED OVER THE PLAINS BY THE WEEKEND. MODELS IN GOOD
AGREEMENT WITH THE 500 MB HEIGHT OF THE HIGH REACHING 1594M TO
1595M.
AT THE SFC A COLD FRONT WILL PUSH ACROSS THE AREA WED...WHICH
SHOULD BE THE FOCUS FOR ISOLD THUNDERSTORMS BY EARLY AFTERNOON AS
CAP WEAKENS. INITIALLY MOISTURE IS LIMIT IN THE COLUMN...WITH
PRECIP H2O AROUND AN INCH...NEAR THE 50 PERCENTILE FOR
AUGUST...HOWEVER AN INCREASE THROUGHOUT THE DAY...POOLING ALONG
THE BOUNDARY...IS EXPECTED. THE DEW PTS ARE EXPECTED IN THE MID
AND UPPER 60S FOR THE AFTERNOON...AND SHOULD BE ENOUGH TO HELP
BREAK THE CAP. SOUNDINGS SUGGEST HIGH BASED STORMS NEAR 8K TO 10K
FEET. DIRECTIONAL SHEAR IS DECENT...HOWEVER LIMITED SPEED SHEAR.
A FEW STRONG STORMS CAN NOT BE RULED OUT...AND WILL BE MONITORED.
WEAK SECONDARY BOUNDARY AND UPPER LEVEL WAVE WILL PUSH INTO THE
NW WED EVENING AND ACROSS NRN NEB THURSDAY. SLIGHT CHANCE POPS
WARRANTED AT THIS TIME...ALTHOUGH CONVECTION ALONG THE COLD FRONT
MAY CAUSE THIS DISTURBANCE TO DIMINISH IN EFFECT. LINGERING
CLOUDS AND SLIGHTLY COOLER AIR BEHIND THE COLD FRONT WILL HOLD
TEMPS IN THE 80S FOR MOST AREAS THURS.
BY FRIDAY THE RIDGE WILL BEGIN TO END THE MAIN THREAT FOR STORMS.
A LEESIDE TROUGH DEVELOPS WHILE A LARGE SFC HIGH EXPENDS ACROSS
THE GREAT LAKES. ACTIVITY IS LIKELY ALONG THE HIGHER TERRAIN/SFC
TROUGH TO THE WEST AND MAY IMPACT THE FAR WESTERN ZONES DUE TO
WESTERLY WINDS. HAVE INCLUDED A SLIGHT CHANCE FOR THE EASTERN
PANHANDLE LATE SATURDAY AS A STRONGER UPPER LEVEL WAVE CROSSES
THE NORTHERN/CENTRAL ROCKIES...OTHERWISE DRY. WITH THE INFLUENCE
OF THE RIDGE...HIGHS WARM BACK INTO THE LOWER TO MID 90S...WELL
ABOVE NORMAL FOR THE LAST HALF OF AUGUST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 100 PM CDT TUE AUG 20 2013
UPPER LEVEL HIGH PRESSURE WILL REMAIN IN FIRM CONTROL ACROSS
WESTERN AND NORTH CENTRAL NEBRASKA THIS AFTERNOON AND TONIGHT. A
WEAK COLD FRONT WILL MOVE INTO FAR NORTHWEST NEBRASKA...WHERE AN
ISOLATED THUNDERSTORM IS POSSIBLE. VFR CONDITIONS WILL
PREVAIL...WITH SURFACE WINDS SOUTH AT 5 TO 15 KTS.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...MASEK
AVIATION...TAYLOR
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
622 AM CDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT TUE AUG 20 2013
TODAY AND TONIGHT...850MB WINDS CONTINUE FROM THE SOUTH WITH A
SLIGHT SOUTHWEST COMPONENT. SPEEDS INCREASE TO AROUND 25 KTS
SUPPORTING 15 TO 25 MPH SFC WIND SPEEDS. A DRYLINE BULGE SHOULD
DEVELOP ACROSS WRN NEB AND THE SANDHILLS SUPPORTING DEEPER
MIXING. SOME OF GUIDANCE SUGGESTS LOW 100S FOR HIGHS. THE PROBLEM
AREA IS NRN NEB AND VALENTINE WHERE HOT DRY AIR WILL BLOW NORTH
OFF THE SANDHILLS. IF THE SANDHILLS ARE DRY THEN THIS AREA WILL
RISE ABOVE 100.
FOR NOW TEMPS ARE A BLEND OF TRIED AND TRUE GUIDANCE FOR HIGHS IN
THE 90S TO 100. WITH H700MB TEMPS RISING TOWARD 16C THIS AFTN
ACROSS WRN NEB THERE COULD BE SOME LOW 100S BUT WE WOULD LIKE TO
SEE A MORE SWRLY COMPONENT TO THE 850 MB WINDS AND 700MB WINDS
DUE WEST VS THE RAP FCSTING SOUTHWEST WINDS AT 700MB.
ISOLATED TSTMS ARE POSSIBLE THIS AFTN ACROSS NWRN NEB AS A COLD
FRONT DROPS IN. A SLIGHT COOLING ALOFT TONIGHT MIGHT ALLOW A FEW
STORMS TO FORM FARTHER EAST ACROSS NRN NEB. OTHERWISE THE HEAT
CONTINUES TODAY WITH DEW POINTS IN THE UPPER 60S EAST OF HIGHWAY
83. THE DRYLINE BULGE SHOULD REACH TO HIGHWAY 83 THIS AFTN AND
THEN RETREAT WEST THIS EVENING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 341 AM CDT TUE AUG 20 2013
SUMMER LIKE WEATHER THROUGH MUCH OF THE MID TO LONG RANGE
FORECAST. UPPER LEVEL RIDGE WILL CONTINUE TO MIGRATE EAST AND
BECOME CENTERED OVER THE PLAINS BY THE WEEKEND. MODELS IN GOOD
AGREEMENT WITH THE 500 MB HEIGHT OF THE HIGH REACHING 1594M TO
1595M.
AT THE SFC A COLD FRONT WILL PUSH ACROSS THE AREA WED...WHICH
SHOULD BE THE FOCUS FOR ISOLD THUNDERSTORMS BY EARLY AFTERNOON AS
CAP WEAKENS. INITIALLY MOISTURE IS LIMIT IN THE COLUMN...WITH
PRECIP H2O AROUND AN INCH...NEAR THE 50 PERCENTILE FOR
AUGUST...HOWEVER AN INCREASE THROUGHOUT THE DAY...POOLING ALONG
THE BOUNDARY...IS EXPECTED. THE DEW PTS ARE EXPECTED IN THE MID
AND UPPER 60S FOR THE AFTERNOON...AND SHOULD BE ENOUGH TO HELP
BREAK THE CAP. SOUNDINGS SUGGEST HIGH BASED STORMS NEAR 8K TO 10K
FEET. DIRECTIONAL SHEAR IS DECENT...HOWEVER LIMITED SPEED SHEAR.
A FEW STRONG STORMS CAN NOT BE RULED OUT...AND WILL BE MONITORED.
WEAK SECONDARY BOUNDARY AND UPPER LEVEL WAVE WILL PUSH INTO THE
NW WED EVENING AND ACROSS NRN NEB THURSDAY. SLIGHT CHANCE POPS
WARRANTED AT THIS TIME...ALTHOUGH CONVECTION ALONG THE COLD FRONT
MAY CAUSE THIS DISTURBANCE TO DIMINISH IN EFFECT. LINGERING
CLOUDS AND SLIGHTLY COOLER AIR BEHIND THE COLD FRONT WILL HOLD
TEMPS IN THE 80S FOR MOST AREAS THURS.
BY FRIDAY THE RIDGE WILL BEGIN TO END THE MAIN THREAT FOR STORMS.
A LEESIDE TROUGH DEVELOPS WHILE A LARGE SFC HIGH EXPENDS ACROSS
THE GREAT LAKES. ACTIVITY IS LIKELY ALONG THE HIGHER TERRAIN/SFC
TROUGH TO THE WEST AND MAY IMPACT THE FAR WESTERN ZONES DUE TO
WESTERLY WINDS. HAVE INCLUDED A SLIGHT CHANCE FOR THE EASTERN
PANHANDLE LATE SATURDAY AS A STRONGER UPPER LEVEL WAVE CROSSES
THE NORTHERN/CENTRAL ROCKIES...OTHERWISE DRY. WITH THE INFLUENCE
OF THE RIDGE...HIGHS WARM BACK INTO THE LOWER TO MID 90S...WELL
ABOVE NORMAL FOR THE LAST HALF OF AUGUST.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 620 AM CDT TUE AUG 20 2013
VFR IS EXPECTED TODAY AND TONIGHT. ISOLATED THUNDERSTORMS ARE
POSSIBLE LATE THIS AFTERNOON ACROSS SHERIDAN AND CHERRY COUNTIES
AND ELSEWHERE ACROSS NORTHERN NEBRASKA TONIGHT. OTHERWISE SCT-
BKN250 CLOUDS ARE EXPECTED TO MOVE THROUGH TODAY AND TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...MASEK
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
341 AM CDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT TUE AUG 20 2013
TODAY AND TONIGHT...850MB WINDS CONTINUE FROM THE SOUTH WITH A
SLIGHT SOUTHWEST COMPONENT. SPEEDS INCREASE TO AROUND 25 KTS
SUPPORTING 15 TO 25 MPH SFC WIND SPEEDS. A DRYLINE BULGE SHOULD
DEVELOP ACROSS WRN NEB AND THE SANDHILLS SUPPORTING DEEPER
MIXING. SOME OF GUIDANCE SUGGESTS LOW 100S FOR HIGHS. THE PROBLEM
AREA IS NRN NEB AND VALENTINE WHERE HOT DRY AIR WILL BLOW NORTH
OFF THE SANDHILLS. IF THE SANDHILLS ARE DRY THEN THIS AREA WILL
RISE ABOVE 100.
FOR NOW TEMPS ARE A BLEND OF TRIED AND TRUE GUIDANCE FOR HIGHS IN
THE 90S TO 100. WITH H700MB TEMPS RISING TOWARD 16C THIS AFTN
ACROSS WRN NEB THERE COULD BE SOME LOW 100S BUT WE WOULD LIKE TO
SEE A MORE SWRLY COMPONENT TO THE 850 MB WINDS AND 700MB WINDS
DUE WEST VS THE RAP FCSTING SOUTHWEST WINDS AT 700MB.
ISOLATED TSTMS ARE POSSIBLE THIS AFTN ACROSS NWRN NEB AS A COLD
FRONT DROPS IN. A SLIGHT COOLING ALOFT TONIGHT MIGHT ALLOW A FEW
STORMS TO FORM FARTHER EAST ACROSS NRN NEB. OTHERWISE THE HEAT
CONTINUES TODAY WITH DEW POINTS IN THE UPPER 60S EAST OF HIGHWAY
83. THE DRYLINE BULGE SHOULD REACH TO HIGHWAY 83 THIS AFTN AND
THEN RETREAT WEST THIS EVENING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 341 AM CDT TUE AUG 20 2013
SUMMER LIKE WEATHER THROUGH MUCH OF THE MID TO LONG RANGE
FORECAST. UPPER LEVEL RIDGE WILL CONTINUE TO MIGRATE EAST AND
BECOME CENTERED OVER THE PLAINS BY THE WEEKEND. MODELS IN GOOD
AGREEMENT WITH THE 500 MB HEIGHT OF THE HIGH REACHING 1594M TO
1595M.
AT THE SFC A COLD FRONT WILL PUSH ACROSS THE AREA WED...WHICH
SHOULD BE THE FOCUS FOR ISOLD THUNDERSTORMS BY EARLY AFTERNOON AS
CAP WEAKENS. INITIALLY MOISTURE IS LIMIT IN THE COLUMN...WITH
PRECIP H2O AROUND AN INCH...NEAR THE 50 PERCENTILE FOR
AUGUST...HOWEVER AN INCREASE THROUGHOUT THE DAY...POOLING ALONG
THE BOUNDARY...IS EXPECTED. THE DEW PTS ARE EXPECTED IN THE MID
AND UPPER 60S FOR THE AFTERNOON...AND SHOULD BE ENOUGH TO HELP
BREAK THE CAP. SOUNDINGS SUGGEST HIGH BASED STORMS NEAR 8K TO 10K
FEET. DIRECTIONAL SHEAR IS DECENT...HOWEVER LIMITED SPEED SHEAR.
A FEW STRONG STORMS CAN NOT BE RULED OUT...AND WILL BE MONITORED.
WEAK SECONDARY BOUNDARY AND UPPER LEVEL WAVE WILL PUSH INTO THE
NW WED EVENING AND ACROSS NRN NEB THURSDAY. SLIGHT CHANCE POPS
WARRANTED AT THIS TIME...ALTHOUGH CONVECTION ALONG THE COLD FRONT
MAY CAUSE THIS DISTURBANCE TO DIMINISH IN EFFECT. LINGERING
CLOUDS AND SLIGHTLY COOLER AIR BEHIND THE COLD FRONT WILL HOLD
TEMPS IN THE 80S FOR MOST AREAS THURS.
BY FRIDAY THE RIDGE WILL BEGIN TO END THE MAIN THREAT FOR STORMS.
A LEESIDE TROUGH DEVELOPS WHILE A LARGE SFC HIGH EXPENDS ACROSS
THE GREAT LAKES. ACTIVITY IS LIKELY ALONG THE HIGHER TERRAIN/SFC
TROUGH TO THE WEST AND MAY IMPACT THE FAR WESTERN ZONES DUE TO
WESTERLY WINDS. HAVE INCLUDED A SLIGHT CHANCE FOR THE EASTERN
PANHANDLE LATE SATURDAY AS A STRONGER UPPER LEVEL WAVE CROSSES
THE NORTHERN/CENTRAL ROCKIES...OTHERWISE DRY. WITH THE INFLUENCE
OF THE RIDGE...HIGHS WARM BACK INTO THE LOWER TO MID 90S...WELL
ABOVE NORMAL FOR THE LAST HALF OF AUGUST.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 101 AM CDT TUE AUG 20 2013
STATISTICAL OUTPUT FROM ONE MODEL INDICATES SOME RISK OF
VISIBILITY BELOW 5SM IN THE PLATTE RIVER VALLEY AROUND LBF. THE
INDICATED PROBABILITY OF THAT VISIBILITY RANGE IS ABOUT 50
PERCENT. THE OTHER STATISTICAL BULLETIN DOES NOT INDICATE ANY
RESTRICTION. THEREFORE...UNLESS THERE IS A STRONGER SIGNAL LATER
IN SATELLITE IMAGERY OR IN THE SURFACE OBSERVATIONS...WE WILL NOT
INCLUDE THE RESTRICTION IN THE TERMINAL FORECAST FOR LBF.
OTHERWISE...NO RESTRICTIVE CEILING OR VISIBILITY IS EXPECTED IN
CENTRAL AND WESTERN NEBRASKA TONIGHT THROUGH TUESDAY. BY ABOUT
16Z TUESDAY...SOUTH WIND 170-200 WILL INCREASE TO 8-12G16-22KT
AND DECREASE AGAIN 00-02Z.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...MASEK
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
930 PM EDT WED AUG 21 2013
.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL CROSS THE MIDATLANTIC REGION TONIGHT
THROUGH THURSDAY. SURFACE HIGH PRESSURE WILL STRENGTHEN ACROSS THE
OHIO VALLEY IN THE WAKE OF THE UPPER LEVEL TROUGH... DRIVING A COLD
FRONT SOUTHWARD INTO THE CAROLINAS ON FRIDAY.
&&
.NEAR TERM /TONIGHT/...
AS OF 930 PM WEDNESDAY...
AFTER QUITE A WET LATE AFTERNOON THROUGH EARLY EVENING ESPECIALLY IN
THE SOUTHEAST CWA... THE REMAINDER OF THE NIGHT SHOULD TREND MUCH
DRIER FOR MOST OF CENTRAL NC. AN AREA OF STRATIFORM RAIN COVERS MUCH
OF THE COASTAL PLAIN... IN THE WAKE OF THE DISORGANIZED BAND OF
STORMS NOW MOVING INTO COASTAL NC. MOST CONVECTION-ALLOWING MODELS
AGREE ON NO SIGNIFICANT ADDITIONAL DEVELOPMENT OVERNIGHT... BUT ONE
EXCEPTION IS THE HRRR WHICH SUGGESTS THAT THE BAND OF CONVECTION NOW
EXTENDING FROM CENTRAL WV INTO SW VA/FAR NW NC (ASSOCIATED WITH DPVA
WITHIN THE MID LEVEL TROUGH) WILL PROGRESS EASTWARD OVER THE NEXT
SEVERAL HOURS... BRUSHING ACROSS THE NRN COUNTIES OF CENTRAL NC.
DEEP LAYER BULK SHEAR WILL REMAIN MARGINAL AT AROUND 25 KTS... BUT
THE RAP INDICATES ELEVATED INSTABILITY (MLCAPE OVER 1000 J/KG)
HOLDING THROUGH THE NIGHT. WITH ABOUT 30 METERS OF HEIGHT FALLS
ANTICIPATED OVERNIGHT IN NRN NC WITH THE TROUGH SHIFTING SLOWLY
EASTWARD JUST TO OUR NW... THIS MAY PROVIDE ENOUGH IMPETUS FOR THESE
STORMS TO HOLD TOGETHER AS THEY PUSH EASTWARD. ONCE THE
POST-CONVECTION RAIN CLEARS OUT OF THE EAST IN THE NEXT HOUR OR
SO... WILL RETAIN AN ISOLATED STORM MENTION OVERNIGHT EVERYWHERE
EXCEPT FOR SCATTERED COVERAGE ACROSS THE NORTH. TEMPS ARE ALREADY
VERY CLOSE TO THEIR ANTICIPATED OVERNIGHT LOWS... SO EXPECT READINGS
TO DIP JUST ANOTHER CATEGORY OR SO OVERNIGHT... RESULTING IN LOWS
69-73. -GIH
&&
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 310 PM WEDNESDAY...
MEAN FLOW WILL BECOME WESTERLY IN THE WAKE OF THE MID/UPPER TROUGH
EXITING THE AREA BETWEEN 12 TO 18Z...FINALLY DRYING OUT THE
THE ABNORMALLY MOIST(PWATS 1.75-2.00 INCHES)AIRMASS THAT HAS BEEN IN
PLACE OVER THE PAST SEVERAL DAYS. THIS DRYING ALONG WITH STRONG
SYNOPTIC SCALE SUBSIDENCE IN THE WAKE OF THE EXITING TROUGH WILL
LIKELY GO A LONG WAYS IN COUNTERACTING AFTERNOON HEATING AND
RESULTANT DESTABILIZATION TO KEEP CONVECTION AT A MINIMUM THURSDAY
AFTERNOON...ESPECIALLY WEST OF US 1. CONVECTIVE ALLOWING MODELS
STRONGLY SUPPORT THE ABOVE RATIONALE...AND AS SUCH HAVE OPTED TO
CUT POPS A BIT WITH SLIGHT/ISOLATED CHANCE IN THE WEST TO SMALL
CHANCE IN THE EAST. DRY THURSDAY NIGHT UNTIL THE ARRIVAL OF THE
COLD FRONT ON FRIDAY.
FULL SUN THICKNESSES WILL FINALLY BE REALIZED ALLOWING NEAR NORMAL
HIGHS IN THE UPPER 80S TO AROUND 90. LOWS THURSDAY NIGHT IN THE
UPPER 60S TO LOWER 70S.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 250 PM WEDNESDAY...
FRIDAY...SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE ON FRIDAY
AS A COLD FRONT MOVES THROUGH THE AREA AND MOISTURE REMAINS
SUFFICIENTLY HIGH (PWAT VALUES 1.75-2 INCHES). MODELS INDICATE
MODERATE INSTABILITY DEVELOPING DURING THE DAY ON FRIDAY...HOWEVER
GIVEN THAT THE STRONGER SHORT WAVE TROUGH WILL HAVE MOVED EAST OF
THE REGION BY FRIDAY MORNING...WEAK SHEAR (GENERALLY LESS THAN 20
KNOTS) IS PROGGED TO BE OVER THE REGION AND SHOULD THEREFORE LIMIT
ANY STORM ORGANIZATION. RAIN CHANCES SHOULD DIMINISH FROM NORTH TO
SOUTH FRIDAY NIGHT AS THE FRONT MOVES TOWARDS THE SC BORDER. HIGHS
WILL LIKELY BE IN THE MID/UPPER 80S TO NEAR 90 DEGREES WITH
OVERNIGHT LOWS GENERALLY IN THE MID/UPPER 60S TO NEAR 70 DEGREES
ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA.
SATURDAY THROUGH TUESDAY...LOWER DEEP LAYER MOISTURE WILL FILTER IN
BEHIND THE DEPARTING FRONT AS STRONG HIGH PRESSURE (ESPECIALLY FOR
AUGUST) BUILDS INTO THE AREA. THIS WILL RESULT IN A MOSTLY DRY
FORECAST...ALTHOUGH THERE COULD BE A COUPLE OF SHOWERS EARLY
SATURDAY MAINLY ACROSS THE SOUTH IN THE VICINITY OF THE SOUTHWARD
SINKING FRONT. DIURNAL TYPE RAIN CHANCES MAY BEGIN TO INCREASE BY
THE MIDDLE OF NEXT AS THE HIGH STARTS TO WEAKEN OVER THE AREA. TEMPS
WILL GENERALLY BE IN THE LOW/MID 80S...WITH A GRADUAL REBOUND BY
EARLY/MID NEXT WEEK.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AS OF 810 PM WEDNESDAY...
A LITTLE LIGHT...VFR RAIN...THE LEFT-OVER MOISTURE FROM EARLIER
STRONG THUNDERSTORMS...WILL LINGER AT KRDU/KFAY/KRWI FOR THE NEXT
COUPLE OF HOURS. THEREAFTER...A PARTLY CLEAR SKY IN CONJUNCTION WITH
GROUND MOISTURE FROM EARLIER RAIN WILL FAVOR THE DEVELOPMENT OF FOG
LATE TONIGHT-EARLY THU. THE LOWEST VISIBILITY RESTRICTIONS...AND
ASSOCIATED VLIFR-IFR CEILINGS...WILL LIKELY OCCUR AT KFAY...WHERE
OVER TWO INCHES OF RAIN FELL DURING THE PAST SEVERAL HOURS. THE LOW
LEVEL MOISTURE SHOULD QUICKLY DISPERSE WITH DEVELOPING WSW FLOW AND
DIURNAL HEATING (BY 13-14Z) THU. THE PASSING OF A MID-UPPER
DISTURBANCE WILL CAUSE SHOWERS AND THUNDERSTORMS TO SCATTER ABOUT
EASTERN TAF SITES MIDDAY THROUGH LATE AFTERNOON THU...BUT
PREDICTABILITY OF TIME AND LOCATION AT PRESENT IS TOO LOW TO INCLUDE
MENTION IN THE TAFS AT THIS TIME.
LOOKING AHEAD:
A COLD FRONT WILL CROSS CENTRAL NC AND RESULT IN ANOTHER ROUND OF
SHOWERS AND STORMS...PARTICULARLY AT SOUTHERN AND EASTERN TERMINALS
WHERE THE TIMING OF THE FRONTAL PASSAGE WILL COINCIDE MORE CLOSELY
WITH PEAK DIURNAL HEATING/DESTABILIZATION. CALM TO LIGHT
NORTHEASTERLY LOW LEVEL FLOW IN MODIFIED CANADIAN SURFACE HIGH
PRESSURE MAY THEN RESULT IN VERY SHALLOW PRE-DAWN RADIATION FOG THIS
WEEKEND...MAINLY AT KRWI.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MWS
NEAR TERM...HARTFIELD
SHORT TERM...CBL
LONG TERM...KRR
AVIATION...MWS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1159 AM EDT TUE AUG 20 2013
.SYNOPSIS...
A REMNANT FRONTAL BOUNDARY WILL REMAIN NEARLY STALLED AND WEAKEN
ACROSS THE REGION THROUGH MID WEEK. A MODERATELY STRONG COLD
FRONT IS EXPECTED LATE FRIDAY NIGHT. THIS WILL USHER COOLER AND
DRIER AIR THIS COMING WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1159 AM TUESDAY...OLD FRONTAL BOUNDARY REMAINS STALLED OVER
THE AREA AND HIGH PWAT VALUES WILL RESULT AREAS OF HEAVY RAIN ACROSS
THE AREA...FAVORED OVER THE EASTERN AND SOUTHERN ZONES WITH NUMEROUS
SHOWERS AND ISOLATED THUNDERSTORMS. MAXIMUM TEMPERATURES SHOULD
REACH THE MIDDLE 80S UNDER A PARTLY TO MOSTLY CLOUDY SKY. MINS
TONIGHT SHOULD FALL TO THE LOWER 70S.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...NEAR SEASONABLE TEMPERATURES ON WEDNESDAY AS
SURFACE HIGH PRESSURE SITS NOT ONLY OVER THE WEST ATLANTIC BUT ALSO
THE SOUTHEASTERN U.S. UPPER LEVEL RIDGE OVER THE WEST ATLANTIC
BEGINS TO RETREAT TO THE EAST WHILE TROUGHINESS STRENGTHENS OVER
OHIO VALLY. ISO TO WIDELY SCATTERED CONVECTION JUST ABOUT AREA-WIDE
BUT STABILIZING OCEAN AIR TO MAKE FOR SLIGHTLY LOWER POPS ALONG THE
COAST. THE UPPER SYSTEM SWINGS BY TO OUR NORTH LATE THURSDAY INTO
THURSDAY NIGHT AND SHOULD LEAD TO A SMALL UPTICK IN RAIN CHANCES.
SOME MID LEVEL DRY AIR WILL ADVECT INTO THE REGION BEHIND THE
TROUGH.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...WESTERN U.S. UPPER RIDGE BUILDS FOR MOST OF THE
PERIOD ALLOWING FOR EASTERN TROUGH TO SHARPEN. PREFRONTAL SURFACE
TROUGH IN THE NW FLOW DRIVEN INTO THE REGION ON FRIDAY TO TOUCH OFF
STORMS DESPITE POSSIBLE RELATIVE DRYNESS IN THE MID LEVELS. THIS IS
FOLLOWED BY WHAT MAY BE A MODERATELY STRONG COLD FRONTAL PASSAGE
FRIDAY NIGHT OR SATURDAY MORNING. SUNDAY AND MONDAY SHOULD BRING IN
SOME COOL AND DRY AIR BY AUGUST STANDARDS.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
AS OF 12Z...LIFR CONDITIONS PRETTY WIDESPREAD THIS MORNING.
CLIMATOLOGICAL TRENDS SUGGEST STRATUS WILL SCATTER BETWEEN 15-16Z.
QUITE A BIT OF MID AND HIGH CLOUDS ABOVE MAY RETARD THE MIXING
PROCESS. HRRR MODEL INDICATES ISOLATED/SCATTERED CONVECTION WILL
FORM ALONG THE RESULTANT BOUNDARY AROUND MIDDAY. COVERAGE WILL BE
SUCH THAT A VCSH SHOULD COVER IT. MOST OF THE ACTIVITY WILL BE
SLIGHTLY INLAND FROM THE COASTAL TERMINALS. CONVECTION ENDS BY EARLY
EVENING...WITH ANOTHER ROUND OF FOG/STRATUS EXPECTED AFTER
MIDNIGHT.
EXTENDED OUTLOOK...EARLY MORNING FOG/STRATUS POSSIBLE WEDNESDAY AND
THURSDAY...ESPECIALLY INLAND. ISOLATED SHOWERS/T-STORMS WEDNESDAY
THROUGH FRIDAY...BECOMING MORE WIDELY SCATTERED ON SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1159 AM TUESDAY...OUTSIDE OF LIGHT AND VARIABLE WINDS EARLY TODAY
DUE TO THE LAND BREEZE FORCING THE FRONT OFF THE COAST...EXPECT SE
TO S FLOW AT 10 KT OR LESS THROUGH THE PERIOD. SEAS ARE EXPECTED TO
RUN 2 TO 3 FT.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...HIGH PRESSURE WILL BE LOCATED WELL OFF THE
COAST BUT THERE WILL ALSO BE A SECONDARY CENTER OVER THE
SOUTHEASTERN U.S. THIS WILL KEEP WIND AND SEAS MINIMAL WITH A
PREDOMINANTLY SWRLY DIRECTION ALTHOUGH THE FLOW MAY BACK TO S OR
EVEN SE AT TIMES ESP ALONG THE IMMEDIATE COAST IN ASSOCIATION WITH
THE SEA BREEZE. AN UPPER LEVEL TROUGH MAY BE STRONG ENOUGH TO ERODE
THE STRENGTH OF BOTH SURFACE HIGHS LATER THURSDAY. A LIGHT SW WIND
WILL BE FOUND ACROSS A LARGE PART OF THE SOUTHEAST COAST WHILE THE
RELATIVELY TRANQUIL SEA STATE REMAINS UNCHANGED.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...WEAK SW FLOW AHEAD OF A PREFRONTAL TROUGH WILL
VEER TO W OR EVEN NW AS THE TROUGH PASSES BY MIDDAY. NO APPRECIABLE
INCREASE IN WIND SPEED AS EXPECTED WITH THE PASSAGE OF THE WIND
SHIFT. LATE FRIDAY NIGHT THIS WILL BE FOLLOWED BY AN ACTUAL FRONTAL
PASSAGE. A FURTHER VEERING AND INCREASE IN WIND SPEED AND SEAS
EXPECTED.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR SCZ053>056.
NC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR NCZ099-
105>110.
MARINE...NONE.
&&
$$
NEAR TERM...RAN/8
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
717 AM EDT TUE AUG 20 2013
.SYNOPSIS...
A REMNANT FRONTAL BOUNDARY WILL REMAIN NEARLY STALLED AND WEAKEN
ACROSS THE REGION THROUGH MID WEEK. A MODERATELY STRONG COLD
FRONT IS EXPECTED LATE FRIDAY NIGHT. THIS WILL USHER COOLER AND
DRIER AIR THIS COMING WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 717 AM TUESDAY...DENSE FOG ADVISORY ISSUED FOR PREVALENT
1/4 MILE VSBYS ALONG THE COAST AND COASTAL INTERIOR. VSBYS AER
EXPECTED TO IMPROVE BY 9AM. THE PREVIOUS DISCUSIION FOLLOWS.
AN OLD FRONTAL BOUNDARY REMAINS STALLED OVER THE AREA AND MODEL
GUIDANCE DEVELOPS ANOTHER UPPER LOW OVER THE MISSISSIPPI VALLEY
DURING THE PERIOD. THE NET RESULT SHOULD BE MORE OF THE SAME
ACROSS THE AREA TODAY WITH SCATTERED SHOWERS AND THUNDERSTORMS
EXPECTED...MAINLY DURING THE AFTERNOON AND EARLY EVENING. MAXIMUM
TEMPERATURES SHOULD REACH THE MIDDLE 80S UNDER A PARTLY TO MOSTLY
CLOUDY SKY. MINS TONIGHT SHOULD FALL TO THE LOWER 70S. AT THIS
TIME DO NOT ANTICIPATE NEEDING A DENSE FOG ADVISORY BUT WIDESPREAD
FOG IS EXPECTED THIS AM...PARTICULARLY OVER EASTERN SECTIONS OF
THE AREA.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...NEAR SEASONABLE TEMPERATURES ON WEDNESDAY AS
SURFACE HIGH PRESSURE SITS NOT ONLY OVER THE WEST ATLANTIC BUT ALSO
THE SOUTHEASTERN U.S. UPPER LEVEL RIDGE OVER THE WEST ATLANTIC
BEGINS TO RETREAT TO THE EAST WHILE TROUGHINESS STRENGTHENS OVER
OHIO VALLY. ISO TO WIDELY SCATTERED CONVECTION JUST ABOUT AREA-WIDE
BUT STABILIZING OCEAN AIR TO MAKE FOR SLIGHTLY LOWER POPS ALONG THE
COAST. THE UPPER SYSTEM SWINGS BY TO OUR NORTH LATE THURSDAY INTO
THURSDAY NIGHT AND SHOULD LEAD TO A SMALL UPTICK IN RAIN CHANCES.
SOME MID LEVEL DRY AIR WILL ADVECT INTO THE REGION BEHIND THE
TROUGH.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...WESTERN U.S. UPPER RIDGE BUILDS FOR MOST OF THE
PERIOD ALLOWING FOR EASTERN TROUGH TO SHARPEN. PREFRONTAL SURFACE
TROUGH IN THE NW FLOW DRIVEN INTO THE REGION ON FRIDAY TO TOUCH OFF
STORMS DESPITE POSSIBLE RELATIVE DRYNESS IN THE MID LEVELS. THIS IS
FOLLOWED BY WHAT MAY BE A MODERATELY STRONG COLD FRONTAL PASSAGE
FRIDAY NIGHT OR SATURDAY MORNING. SUNDAY AND MONDAY SHOULD BRING IN
SOME COOL AND DRY AIR BY AUGUST STANDARDS.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
AS OF 12Z...LIFR CONDITIONS PRETTY WIDESPREAD THIS MORNING.
CLIMATOLOGICAL TRENDS SUGGEST STRATUS WILL SCATTER BETWEEN 15-16Z.
QUITE A BIT OF MID AND HIGH CLOUDS ABOVE MAY RETARD THE MIXING
PROCESS. HRRR MODEL INDICATES ISOLATED/SCATTERED CONVECTION WILL
FORM ALONG THE RESULTANT BOUNDARY AROUND MIDDAY. COVERAGE WILL BE
SUCH THAT A VCSH SHOULD COVER IT. MOST OF THE ACTIVITY WILL BE
SLIGHTLY INLAND FROM THE COASTAL TERMINALS. CONVECTION ENDS BY EARLY
EVENING...WITH ANOTHER ROUND OF FOG/STRATUS EXPECTED AFTER
MIDNIGHT.
EXTENDED OUTLOOK...EARLY MORNING FOG/STRATUS POSSIBLE WEDNESDAY AND
THURSDAY...ESPECIALLY INLAND. ISOLATED SHOWERS/T-STORMS WEDNESDAY
THROUGH FRIDAY...BECOMING MORE WIDELY SCATTERED ON SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM TUESDAY...OUTSIDE OF LIGHT AND VARIABLE WINDS EARLY TODAY
DUE TO THE LAND BREEZE FORCING THE FRONT OFF THE COAST...EXPECT SE
TO S FLOW AT 10 KT OR LESS THROUGH THE PERIOD. SEAS ARE EXPECTED TO
RUN 2 TO 3 FT.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...HIGH PRESSURE WILL BE LOCATED WELL OFF THE
COAST BUT THERE WILL ALSO BE A SECONDARY CENTER OVER THE
SOUTHEASTERN U.S. THIS WILL KEEP WIND AND SEAS MINIMAL WITH A
PREDOMINANTLY SWRLY DIRECTION ALTHOUGH THE FLOW MAY BACK TO S OR
EVEN SE AT TIMES ESP ALONG THE IMMEDIATE COAST IN ASSOCIATION WITH
THE SEA BREEZE. AN UPPER LEVEL TROUGH MAY BE STRONG ENOUGH TO ERODE
THE STRENGTH OF BOTH SURFACE HIGHS LATER THURSDAY. A LIGHT SW WIND
WILL BE FOUND ACROSS A LARGE PART OF THE SOUTHEAST COAST WHILE THE
RELATIVELY TRANQUIL SEA STATE REMAINS UNCHANGED.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...WEAK SW FLOW AHEAD OF A PREFRONTAL TROUGH WILL
VEER TO W OR EVEN NW AS THE TROUGH PASSES BY MIDDAY. NO APPRECIABLE
INCREASE IN WIND SPEED AS EXPECTED WITH THE PASSAGE OF THE WIND
SHIFT. LATE FRIDAY NIGHT THIS WILL BE FOLLOWED BY AN ACTUAL FRONTAL
PASSAGE. A FURTHER VEERING AND INCREASE IN WIND SPEED AND SEAS
EXPECTED.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR SCZ053>056.
NC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR NCZ099-
105>110.
MARINE...NONE.
&&
$$
NEAR TERM...RAN/8
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
703 AM EDT TUE AUG 20 2013
.SYNOPSIS...
A FRONT WILL REMAIN NEARLY STALLED AND WEAKEN ACROSS THE REGION
THROUGH THE MIDDLE OF THE WEEK. A MODERATELY STRONG COLD FRONT IS
EXPECTED LATE FRIDAY NIGHT. THIS WILL USHER IN SOME COOLER AND
DRIER AIR THIS COMING WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM TUESDAY...AN OLD FRONTAL BOUNDARY REMAINS STALLED OVER
THE AREA AND MODEL GUIDANCE DEVELOPS ANOTHER UPPER LOW OVER THE
MISSISSIPPI VALLEY DURING THE PERIOD. THE NET RESULT SHOULD BE MORE
OF THE SAME ACROSS THE AREA TODAY WITH SCATTERED SHOWERS AND
THUNDERSTORMS EXPECTED...MAINLY DURING THE AFTERNOON AND EARLY
EVENING. MAXIMUM TEMPERATURES SHOULD REACH THE MIDDLE 80S UNDER A
PARTLY TO MOSTLY CLOUDY SKY. MINS TONIGHT SHOULD FALL TO THE LOWER
70S. AT THIS TIME DO NOT ANTICIPATE NEEDING A DENSE FOG ADVISORY
BUT WIDESPREAD FOG IS EXPECTED THIS AM...PARTICULARLY OVER EASTERN
SECTIONS OF THE AREA.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...NEAR SEASONABLE TEMPERATURES ON WEDNESDAY AS
SURFACE HIGH PRESSURE SITS NOT ONLY OVER THE WEST ATLANTIC BUT ALSO
THE SOUTHEASTERN U.S. UPPER LEVEL RIDGE OVER THE WEST ATLANTIC
BEGINS TO RETREAT TO THE EAST WHILE TROUGHINESS STRENGTHENS OVER
OHIO VALLY. ISO TO WIDELY SCATTERED CONVECTION JUST ABOUT AREA-WIDE
BUT STABILIZING OCEAN AIR TO MAKE FOR SLIGHTLY LOWER POPS ALONG THE
COAST. THE UPPER SYSTEM SWINGS BY TO OUR NORTH LATE THURSDAY INTO
THURSDAY NIGHT AND SHOULD LEAD TO A SMALL UPTICK IN RAIN CHANCES.
SOME MID LEVEL DRY AIR WILL ADVECT INTO THE REGION BEHIND THE
TROUGH.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...WESTERN U.S. UPPER RIDGE BUILDS FOR MOST OF THE
PERIOD ALLOWING FOR EASTERN TROUGH TO SHARPEN. PREFRONTAL SURFACE
TROUGH IN THE NW FLOW DRIVEN INTO THE REGION ON FRIDAY TO TOUCH OFF
STORMS DESPITE POSSIBLE RELATIVE DRYNESS IN THE MID LEVELS. THIS IS
FOLLOWED BY WHAT MAY BE A MODERATELY STRONG COLD FRONTAL PASSAGE
FRIDAY NIGHT OR SATURDAY MORNING. SUNDAY AND MONDAY SHOULD BRING IN
SOME COOL AND DRY AIR BY AUGUST STANDARDS.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 12Z...LIFR CONDITIONS PRETTY WIDESPREAD THIS MORNING.
CLIMATOLOGICAL TRENDS SUGGEST STRATUS WILL SCATTER BETWEEN 15-16Z.
QUITE A BIT OF MID AND HIGH CLOUDS ABOVE MAY RETARD THE MIXING
PROCESS. HRRR MODEL INDICATES ISOLATED/SCATTERED CONVECTION WILL
FORM ALONG THE RESULTANT BOUNDARY AROUND MIDDAY. COVERAGE WILL BE
SUCH THAT A VCSH SHOULD COVER IT. MOST OF THE ACTIVITY WILL BE
SLIGHTLY INLAND FROM THE COASTAL TERMINALS. CONVECTION ENDS BY EARLY
EVENING...WITH ANOTHER ROUND OF FOG/STRATUS EXPECTED AFTER
MIDNIGHT.
EXTENDED OUTLOOK...EARLY MORNING FOG/STRATUS POSSIBLE WEDNESDAY AND
THURSDAY...ESPECIALLY INLAND. ISOLATED SHOWERS/T-STORMS WEDNESDAY
THROUGH FRIDAY...BECOMING MORE WIDELY SCATTERED ON SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM TUESDAY...OUTSIDE OF LIGHT AND VARIABLE WINDS EARLY TODAY
DUE TO THE LAND BREEZE FORCING THE FRONT OFF THE COAST...EXPECT SE
TO S FLOW AT 10 KT OR LESS THROUGH THE PERIOD. SEAS ARE EXPECTED TO
RUN 2 TO 3 FT.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...HIGH PRESSURE WILL BE LOCATED WELL OFF THE
COAST BUT THERE WILL ALSO BE A SECONDARY CENTER OVER THE
SOUTHEASTERN U.S. THIS WILL KEEP WIND AND SEAS MINIMAL WITH A
PREDOMINANTLY SWRLY DIRECTION ALTHOUGH THE FLOW MAY BACK TO S OR
EVEN SE AT TIMES ESP ALONG THE IMMEDIATE COAST IN ASSOCIATION WITH
THE SEA BREEZE. AN UPPER LEVEL TROUGH MAY BE STRONG ENOUGH TO ERODE
THE STRENGTH OF BOTH SURFACE HIGHS LATER THURSDAY. A LIGHT SW WIND
WILL BE FOUND ACROSS A LARGE PART OF THE SOUTHEAST COAST WHILE THE
RELATIVELY TRANQUIL SEA STATE REMAINS UNCHANGED.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...WEAK SW FLOW AHEAD OF A PREFRONTAL TROUGH WILL
VEER TO W OR EVEN NW AS THE TROUGH PASSES BY MIDDAY. NO APPRECIABLE
INCREASE IN WIND SPEED AS EXPECTED WITH THE PASSAGE OF THE WIND
SHIFT. LATE FRIDAY NIGHT THIS WILL BE FOLLOWED BY AN ACTUAL FRONTAL
PASSAGE. A FURTHER VEERING AND INCREASE IN WIND SPEED AND SEAS
EXPECTED.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MBB
NEAR TERM...RAN
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...43
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1141 PM CDT MON AUG 19 2013
.UPDATE...
ISSUED AT 940 PM CDT MON AUG 19 2013
THE MAIN ISSUE OVERNIGHT WILL BE POSSIBLE FOG FORMATION. CLEAR SKY
AND HIGH LOW LEVEL MOISTURE WILL BE PRESENT...BUT THERE MAY BE
ENOUGH LOW LEVEL MIXING TO PREVENT FOG. 01Z RAP INDICATES A 30-40
KNOT LOW LEVEL JET FROM SOUTH CENTRAL NORTH DAKOTA INTO NORTHWEST
MINNESOTA. ALTHOUGH MIXING WILL NOT BE VERY DEEP DUE TO
NIGHTTIME...THERE SHOULD BE ENOUGH MIXING TO PREVENT CALM WINDS AT
THE SURFACE FOR THIS AREA. FURTHER TO THE SOUTHEAST...AWAY FROM
THE STRONGER 925MB-850MB WINDS...MODELS INDICATE VERY LIGHT FLOW.
AT LEAST PATCHY FOG SHOULD OCCUR HERE...AND INSERTED WITHIN
PORTIONS OF WEST CENTRAL MINNESOTA. THE MAIN AREAS TO WATCH WILL
BE AROUND LAKES AND THE BEMIDJI AREA (WHERE 1 TO 3 INCHES OF RAIN
FELL THIS AFTERNOON). OTHERWISE...MIN TEMPS AND OTHER PARAMETERS
ARE IN GOOD SHAPE.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 340 PM CDT MON AUG 19 2013
PRIMARY CHALLENGES ARE TEMPERATURES THROUGH THE PERIOD AND
PRECIPITATION CHANCES TUESDAY NIGHT. MODELS ARE IN REASONABLE
AGREEMENT AND WILL USE A BLENDED SOLUTION.
A NEARLY STATIONARY ISOLATED CLUSTER OF SHOWERS AND ISOLATED
THUNDERSTORMS HAS DEVELOPED ACROSS SOUTHERN BELTRAMI COUNTY THIS
AFTERNOON...POSSIBLY DUE TO SOME KIND OF LAKE BREEZE INTERACTIONS...
SO ADDED SOME CHANCE POPS IN THIS AREA UNTIL 02 UTC. REST OF THE
FORECAST AREA IS HOT AND DRY WITH LITTLE CLOUD COVER. WHAT LITTLE
CU HAS DEVELOPED WILL DISSIPATE AFTER SUNSET WITH CLEAR SKIES
OVERNIGHT. WITH A WARM AIR MASS AND ELEVATED SOUTHERLY WIND...LOWS
WILL DROP INTO THE MID TO UPPER 60S.
IT/S SAFE TO SAY TUESDAY WILL BE THE HOTTEST DAY SO FAR OF THE
YEAR. AN 850 HPA +28 C THERMAL RIDGE WILL MOVE ACROSS THE FORECAST
AREA AHEAD OF AN ADVANCING COLD FRONT. WITH A DRY ADIABATIC
BOUNDARY LAYER DEEPENING TO 700 TO 600 HPA...IT WILL NOT BE
DIFFICULT FOR MUCH OF THIS HEAT TO MIX TO THE SURFACE. EXPECT
AFTERNOON HIGHS REGION WIDE IN THE LOWER TO MID 90S. ONLY
EXCEPTION MAY BE THE FAR NORTHWEST FORECAST AREA WHICH WILL BE
UNDER THE INFLUENCE OF THE COLD FRONTAL PASSAGE A BIT EARLIER IN
THE DAY. WITH DEW POINT TEMPERATURES ALONG AND AHEAD OF THE FRONT
IN THE 60S...HEAT INDICIES NEARING 100 DEGREES NOT OUT OF THE
QUESTION. WILL HOLD ON A HEAT ADVISORY...BUT SOMETHING TO CONSIDER
IN LATER SHIFTS.
WILL HOLD 20 POPS TUESDAY EVENING AND OVERNIGHT FOR THE CHANCE FOR
SOME CONVECTIVE DEVELOPMENT ALONG AND AHEAD OF THE COLD FRONT.
MLCAPE UP TO 2000 J/KG IS POSSIBLE...BUT 0 TO 6 KM BULK SHEAR IS
RATHER WEAK WITH THE PRIMARY UPPER JET NORTH OF THE CANADIAN
BORDER. VERY WARM MID-LEVEL TEMPERATURES WILL PLAY HAVOC WITH
EROSION OF THE CAP AND DEEP LAYERED MOISTURE IS MISSING. MAIN
INGREDIENTS FOR CONVECTION JUST DON/T SEEM TO ALIGN...SO WHILE
THERE EXISTS SOME CHANCE FOR SHOWERS AND THUNDERSTORMS...
CONFIDENCE IS LOW.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 340 PM CDT MON AUG 19 2013
WEDNESDAY AND THURSDAY WILL BE DRY AS SURFACE HIGH PRESSURE BUILDS
ACROSS THE REGION...BUT COOLER IN THE WAKE OF TUESDAY NIGHT/S FRONTAL
PASSAGE. DAYTIME HIGHS WILL BE IN THE 80S WITH LIGHT WINDS.
OVERNIGHT LOWS WILL RANGE FROM THE MID 50S TO THE MID 60S.
FOR FRIDAY INTO EARLY NEXT WEEK AREA IS ON THE NORTHERN EDGE OF AN
UPPER RIDGE. SEVERAL SHORT WAVES ARE FORECAST TO RIDE FROM THE
PACIFIC COAST 500 MB TROUGH NORTH AND NORTHEAST THRU WYOMING AND
THEN ACROSS NORTH DAKOTA-MINNESOTA THRU THE PERIOD. ANY SHORT WAVE
MAY CAUSE DEVELOPMENT OF ISOLD-SCT TSRA AT ANYTIME THRU THIS PD...SO
WILL GO ALONG WITH CENTRAL REGION ALL BLEND TOOL AND KEEP LOW POPS
IN MOST DAYS FRI-MON. STILL WARM AND HUMID WITH HIGHS IN THE 80S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1141 PM CDT MON AUG 19 2013
THE POTENTIAL EXISTS FOR FOG AT KBJI. THE AIRPORT RECEIVED VERY
LITTLE RAINFALL THIS PAST AFTERNOON...BUT AREAS JUST TO THE EAST
RECEIVED 1 TO 3 INCHES. WIND SPEEDS ALONG AND WEST OF THE VALLEY
WILL BE 5-10 KNOTS OVERNIGHT...BUT LIGHT AND VARIABLE AT KBJI.
CONFIDENCE HAS INCREASED IN FOG FORMATION...AND MENTIONED IN THE
KBJI TAF. OTHERWISE...MOSTLY CLEAR SKY THROUGH THE PERIOD WITH
ONLY WIDELY SCATTERED THUNDERSTORMS TUESDAY EVENING.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...TG
SHORT TERM...ROGERS
LONG TERM...RIDDLE
AVIATION...TG
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
923 PM EDT WED AUG 21 2013
.SYNOPSIS...
UPPER LEVEL LOW PRESSURE WILL DRIFT ACROSS CENTRAL OHIO TONIGHT AS
A COLD FRONT MOVES INTO THE CENTRAL GREAT LAKES. A COLD FRONT IS
EXPECTED TO CROSS THE REGION THURSDAY. HIGH PRESSURE THEN BUILDS
BACK INTO THE AREA FOR FRIDAY INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
UPDATE...UPDATED POPS TO REMOVE CHANCE OF PRECIP UNTIL "TOWARDS
MORNING" NORTHWEST. HRRR BRING SHOWERS CLOSE WITH THE APPROACHING
FRONT. OTHERWISE NO BIG CHANGES.
ORIGINAL... UPPER LEVEL LOW PRESSURE NEAR THE OHIO/INDIANA BORDER
WILL CONTINUE A SLOW MOVE TO THE EAST THROUGH THE NIGHT. AFTERNOON
HEATING COMBINED WITH SOME MOISTURE AROUND 850MB HAS BEEN ENOUGH
TO INITIATE SHOWERS AND THUNDERSTORMS ACROSS CENTRAL AND SOUTHERN
OHIO. THESE WILL ATTEMPT TO MOVE INTO THE SOUTHERN CWA THROUGH THE
EVENING. OUTFLOW FROM MORNING THUNDERSTORMS OVER WESTERN CENTRAL
OHIO HAS BEEN ENOUGH TO PROVIDE SOME LOW LEVEL CONVERGENCE ACROSS
THE SOUTHWESTERN COUNTY WARNING AREA. THESE STORMS MY BE LOCALLY
STRONG WITH SMALL HAIL AND A WIND GUST UP TO 50 MPH. THESE
ISOLATED THUNDERSTORMS SHOULD DECREASE IN COVERAGE AFTER SUNSET.
WE WILL THEN MONITOR TO SEE IF SHOWERS WILL CONTINUE UNDER THE
UPPER LOW THROUGH THE NIGHT AS LIFT CONTINUES ON THE EASTERN SIDE
OF THE LOW. ONLY SLIM CHANCES OF THUNDER AFTER SUNSET.
OUR ATTENTION WILL THEN SHIFT THE THE UPPER GREAT LAKES TO SEE HOW
MUCH CONVECTION DEVELOPS AHEAD OF A COLD FRONT. THIS COLD SHOULD
MOVE INTO MICHIGAN OVERNIGHT WITH SOME WEAKENING CONVECTION MOVING
TOWARD NW OHIO AROUND SUNRISE.
THERE WILL BE MORE CLOUD COVER OVER THE AREA TONIGHT. THESE CLOUDS
COMBINED WITH THE SLIGHTLY HIGHER MOISTURE LEVELS SHOULD ALLOW FOR
A WARMER NIGHT THEN THE LAST FEW.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/...
A COLD FRONT WILL SLOWLY MOVE ACROSS THE AREA ON THURSDAY WITH
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS EXPECTED ALONG AND
AHEAD OF IT. FORTUNATELY THE MAIN CORE OF THE JET ENERGY WILL
REMAIN WELL NORTH OF THE AREA. SO WITH MARGINAL SHEAR OVER THE
REGION WE WILL NEED TO RELY ON THE AMOUNT OF CAPE THAT CAN BE
REALIZED AHEAD OF THE THICKER CLOUD COVER. AT THIS POINT WE BELIEVE
THERE WILL BE SOME ISOLATED STRONGER STORMS. THE FRONT/OUTFLOW
SHOULD MOVE SOUTH OF THE AREA AFTER MIDNIGHT THURSDAY NIGHT WITH
ALL THE SHOWERS ENDING BY SUNRISE. HIGH PRESSURE WILL TAKE CONTROL
OF THE REGION ON FRIDAY AND CONTINUE INTO THE WEEKEND.
CLOUD COVER WILL DICTATE HIGHS ON THURSDAY BUT APPEARS WE SHOULD
STILL REACH THE 80S AT MOST LOCATIONS. SLIGHTLY COOLER FRIDAY INTO
SATURDAY IN THE WAKE OF THE FRONT.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
LITTLE CHANGE IN THE EXTENDED PERIOD. HOT AND MUGGY CONDITIONS WILL
RETURN THIS WEEKEND AND LINGER INTO EARLY NEXT WEEK. ECMWF CONTINUE
TO HINT AT SHORTWAVE ACROSS EASTERN LAKES MONDAY...WHILE GFS DRY.
FOR NOW WILL GO WITH CONTINUITY AND KEEP SLIGHT CHANCE GOING.
ALTHOUGH THEY DIFFER ON THE TRACK...BOTH THE GFS AND ECMWF COMING
INTO A LITTLE BETTER AGREEMENT MOVING THE NEXT SHORT WAVE THROUGH
TUESDAY NIGHT INTO WEDNESDAY. LEANING MORE TOWARD GFS...BUT FOR NOW
WILL JUST KEEP CHANCE POPS GOING TUESDAY NIGHT INTO WEDNESDAY.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
VFR SHOULD PREVAIL UNTIL AFTER 06Z WHEN SOME MVFR FOG MAY DEVELOP
OVER THE INLAND TAFS SITES. THE FOG WILL GRADUALLY DISSIPATE BETWEEN
12Z AND 14Z THU MORNING.
A COLD FRONT WILL DROP SSE ACROSS THE AREA BETWEEN 16Z AND 03Z THU
EVE. MOISTURE AND DYNAMICS LIMITED...SO MAY ONLY SEE SCT CONVECTION
WITH THIS FRONT. FOR NOW WILL ONLY CARRY VCTS STARTING IN TOL BY
LATE MORNING AND PROGRESSING SSE INTO THE REST OF THE SITES THRU 20Z
AS DAYTIME HEATING TRIGGERS THE SCT TSRA.
OUTLOOK ...NON-VFR PROBABLE IN SCT THUNDERSTORMS THURSDAY EVENING AS
A COLD FRONT FINISHES MOVING SOUTH ACROSS THE AREA.
&&
.MARINE...
LIGHT SOUTH TO SOUTHWEST WINDS CONTINUE TONIGHT. SOUTHWEST FLOW
WILL INCREASE TO 10 TO 15 KNOTS AHEAD OF APPROACHING COLD FRONT
PUSHING WAVES TO 2 TO 4 FEET ON THE EAST END. COLD FRONT GOES
THROUGH TOMORROW EVENING COLD FRONT. THUNDERSTORMS WILL DEVELOP
AHEAD OF THE FRONT TOMORROW AFTERNOON INTO THE EVENING. SOME OF
THESE THUNDERSTORMS MAY REQUIRE SPECIAL MARINE WARNINGS.
BEHIND THE FRONT THE WINDS WILL BECOME NORTH TO NORTHEAST. FOR NOW
EXPECT CONDITIONS TO REMAIN JUST BELOW SMALL CRAFT ADVISORY
CRITERIA. HIGH PRESSURE WILL BUILD OVER THE LAKE FRIDAY AND REMAIN
OVER THE LAKE INTO EARLY NEXT WEEK.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MULLEN
NEAR TERM...TK
SHORT TERM...MULLEN
LONG TERM...DJB
AVIATION...ADAMS
MARINE...DJB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
625 AM EDT TUE AUG 20 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH MID
WEEK WITH A WEAK COLD FRONT CROSSING THE AREA LATE THURSDAY. HIGH
PRESSURE THEN BUILDS BACK INTO THE AREA FOR THE REST OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
A FANTASTIC TUESDAY IS ON TAP FOR TODAY. FOG OUT THERE IS LESS
WIDESPREAD THAN YESTERDAY MORNING AND IS RESTRICTED TO THE LOW
SPOTS/VALLEYS. SOME STRATOCU FLOATING AROUND ACROSS NRN OH...BUT
OTHERWISE A MOSTLY CLEAR START. HIGH PRESSURE WILL REMAIN IN
CONTROL ACROSS THE REGION. AN UPPER WAVE WILL CLOSE OFF AND CUT
OFF...REMAINING TO OUR WEST. RIGHT NOW JUST SOME HIGH CLOUD
ASSOCIATED WITH IT. NOT EXPECTING TOO MUCH TO MAKE IT TO THE I-75
CORRIDOR. OTHERWISE JUST A FEW CUMULUS THIS AFTERNOON. WILL TACK
ON A COUPLE MORE DEGREES TO YESTERDAYS HIGHS MAKING IT LOWER AND
MID 80S. MINOR CHANGES FOR THIS EARLY MORNING UPDATE.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
CONTINUED QUIET TONIGHT. MAY BE GETTING A FEW CLOUDS ENCROACH FROM
THE SOUTH OVERNIGHT AS THE UPPER LOW TO OUR WEST BEGINS TO DRIFT
TO SOUTHERN OHIO FOR WEDNESDAY. THIS UPPER LOW WILL LIKELY BE
ENOUGH TO PROVIDE FOR A LITTLE INSTABILITY. SHOWERS/TS WILL BE FAR
FROM WIDESPREAD AND WILL REMAIN IN CLOSE PROXIMITY TO THE UPPER
LOW. THEREFORE HAVE CONTINUED THE LOW PRECIP CHANCES ALONG/SOUTH
OF US 30. MID 80S WEDNESDAY. NOT OUT OF THE QUESTION THAT THERE
MAY BE AN ISOLATED SHOWER/TS WEDNESDAY NIGHT/EARLY THURSDAY ACROSS
THE EASTERN PORTION OF THE AREA WITH UPPER LOW PULLING INTO PA.
UPSTREAM A SHORTWAVE WITH MUCH OF ITS PUSH ACROSS THE NORTHERN
LAKES AND CANADA WILL ABSORB THE LINGERING LOW ACROSS WESTERN PA
THURSDAY. THIS SYSTEM WILL BRING A COLD FRONT ACROSS THURSDAY
AFTERNOON/EVENING. EXPECTING SCATTERED CONVECTION WITH THIS FRONT.
HIGH PRESSURE BUILDS ACROSS THE GREAT LAKES FOR FRIDAY. THE MODEL
TREND HAS BEEN FOR THIS HIGH TO BUILD IN WELL BRINGING DRIER AND
SOMEWHAT COOLER AIR TO THE AREA FOR FRIDAY AND PUSHING THE FRONT
SOUTH OF THE CWA. THERE IS A CHANCE THAT THE FRONT COULD BE
SLOWER...BUT WITH THE BUILDING RIDGE ACROSS THE PLAINS WOULD WANT
TO BELIEVE THAT THE HIGH WILL WIN OUT.
AFTER MILD AND SOMEWHAT HUMID CONDITIONS THURSDAY...WILL SHAVE A
FEW DEGREES OFF OF HIGHS AND BRING IN THE CLEARING FOR FRIDAY.
FRIDAY NIGHT HAS THE POTENTIAL TO BE COOL AGAIN...WITH LOWS IN THE
50S. SOME UPPER 40S NOT OUT OF THE QUESTION.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
DRY TO START WITH HIGH PRESSURE IN CONTROL AT THE SURFACE. THE
HIGH WILL MOVE SOUTHEAST ON MONDAY. DRY WEATHER FOR THE WEEKEND.
HOWEVER THE 12Z ECMWF WAS GIVING SOME QPF ON SUNDAY OVER NORTHWEST
OHIO. THE 00Z RUN WAS KEEPING THE QPF NORTH. WITH SO MUCH HIGH
PRESSURE AT THE SURFACE AND HIGH PRESSURE BUILDING IN ALOFT...KEPT
IT DRY.
FOR MONDAY AND MONDAY NIGHT SOME OF THE OLD MODEL RUNS HAD QPF WITH
SOME MOISTURE CATCHING THE AREA IN THE NORTHWEST FLOW. THE 00Z ECMWF
WAS STILL HINTING AT THIS. KEPT 20% POPS FROM THE PREVIOUS FORECAST.
CONFIDENCE IS LOW IN THIS WITH PLENTY OF RIDGING AND DRYING ALOFT
GOING ON.
TEMPERATURES WILL BE WARMING TO ABOVE NORMAL READINGS FOR THIS
PERIOD.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
A RIDGE WILL CONTINUE WEST TO EAST ACROSS THE FORECAST AREA
THROUGH THE TAF PERIOD.
AN AREA OF BROKEN CLOUDS AT 6000 FEET WAS MOVING ACROSS THE
REGION FOR THE EARLY MORNING HOURS. OTHERWISE THE TEMPERATURE AND DEW
POINT SPREADS WERE GETTING SMALLER. NOT EXPECTING THE IFR FOG AND
STRATUS TO BE AS WIDESPREAD AS IT WAS YESTERDAY...THE AIRMASS
DRIED OUT SOME ESPECIALLY ALOFT. MAINLY FOG IS EXPECTED. THE HRRR
MODEL WHICH DID A VERY GOOD JOB WITH THE STRATUS AND FOG MONDAY
MORNING. THIS MORNING THE HRRR MODEL IS NOT FORECASTING ANY MVFR
OR IFR STRATUS AND NO IFR VISIBILITIES. THIS SEEMS GOOD. MOST TAF
SITES EXCEPT CLE AND ERI WILL HAVE SOME FOG. THE BEST CHANCE FOR
SIGNIFICANT IFR CONDITIONS WILL BE CAK AND YNG...ELSEWHERE IFR FOG
WILL BE BRIEF. THE FOG WILL BURN OFF BY 10 AM AND THEN SOME
SCATTERED CUMULUS WILL DEVELOP AND DISSIPATE IN THE EVENING. A
LAKE BREEZE WILL OCCUR.
OUTLOOK ...NON-VFR POSSIBLE IN EARLY MORNING FOG WEDNESDAY THROUGH
THURSDAY AND IN THUNDERSTORMS THURSDAY AFTERNOON AND EVENING.
&&
.MARINE...
A RIDGE WILL CONTINUE OVER THE LAKE TODAY AND THEN START TO WEAKEN
ON WEDNESDAY. THE FLOW WILL BE MAINLY LIGHT WITH AN ONSHORE FLOW
DURING THE AFTERNOONS.
A SOUTHWEST FLOW WEDNESDAY NIGHT AND THURSDAY AHEAD OF A COLD FRONT
THAT WILL MOVE THROUGH DURING THE AFTERNOON. SPECIAL MARINE WARNINGS
FOR THUNDERSTORMS MAY BE NEEDED THURSDAY AFTERNOON. THE BIGGEST
QUESTION IS HOW STRONG WILL THE WINDS BE BEHIND THE COLD FRONT. IT
IS POSSIBLE THAT THE WINDS COULD PROMPT THE NEED FOR A SMALL CRAFT
ADVISORY FOR THURSDAY EVENING THROUGH DAYBREAK FRIDAY. THIS WILL
HAVE TO BE MONITORED.
HIGH PRESSURE WILL THEN BUILD OVER THE LAKE ON FRIDAY AND CONTINUE
OVER THE EASTERN LAKES THROUGH MUCH OF THE WEEKEND. THE FLOW WILL BE
NORTHEAST AT TIMES. IT DOES NOT LOOK LIKE THE WINDS WILL BE STRONG
ENOUGH TO NEED A SMALL CRAFT ADVISORY.
THE HIGH WILL MOVE EAST FOR EARLY NEXT WEEK WITH A SOUTHWEST FLOW ON
THE LAKE.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...OUDEMAN
NEAR TERM...OUDEMAN
SHORT TERM...OUDEMAN
LONG TERM...KIELTYKA
AVIATION...KIELTYKA
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
329 AM EDT TUE AUG 20 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH MID
WEEK WITH A WEAK COLD FRONT CROSSING THE AREA LATE THURSDAY. HIGH
PRESSURE THEN BUILDS BACK INTO THE AREA FOR THE REST OF THE WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
A FANTASTIC TUESDAY IS ON TAP FOR TODAY. FOG OUT THERE IS LESS
WIDESPREAD THAN YESTERDAY MORNING AND IS RESTRICTED TO THE LOW
SPOTS/VALLEYS. SOME STRATOCU FLOATING AROUND FROM SANDUSKY TO
UPPER SANDUSKY...BUT OTHERWISE A MOSTLY CLEAR START. HIGH PRESSURE
WILL REMAIN IN CONTROL ACROSS THE REGION. AN UPPER WAVE WILL CLOSE
OFF AND CUT OFF...REMAINING TO OUR WEST. RIGHT NOW JUST SOME HIGH
CLOUD ASSOCIATED WITH IT. NOT EXPECTING TOO MUCH TO MAKE IT TO THE
I-75 CORRIDOR. OTHERWISE JUST A FEW CUMULUS THIS AFTERNOON. WILL
TACK ON A COUPLE MORE DEGREES TO YESTERDAYS HIGHS MAKING IT LOWER
AND MID 80S.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
CONTINUED QUIET TONIGHT. MAY BE GETTING A FEW CLOUDS ENCROACH FROM
THE SOUTH OVERNIGHT AS THE UPPER LOW TO OUR WEST BEGINS TO DRIFT
TO SOUTHERN OHIO FOR WEDNESDAY. THIS UPPER LOW WILL LIKELY BE
ENOUGH TO PROVIDE FOR A LITTLE INSTABILITY. SHOWERS/TS WILL BE FAR
FROM WIDESPREAD AND WILL REMAIN IN CLOSE PROXIMITY TO THE UPPER
LOW. THEREFORE HAVE CONTINUED THE LOW PRECIP CHANCES ALONG/SOUTH
OF US 30. MID 80S WEDNESDAY. NOT OUT OF THE QUESTION THAT THERE
MAY BE AN ISOLATED SHOWER/TS WEDNESDAY NIGHT/EARLY THURSDAY ACROSS
THE EASTERN PORTION OF THE AREA WITH UPPER LOW PULLING INTO PA.
UPSTREAM A SHORTWAVE WITH MUCH OF ITS PUSH ACROSS THE NORTHERN
LAKES AND CANADA WILL ABSORB THE LINGERING LOW ACROSS WESTERN PA
THURSDAY. THIS SYSTEM WILL BRING A COLD FRONT ACROSS THURSDAY
AFTERNOON/EVENING. EXPECTING SCATTERED CONVECTION WITH THIS FRONT.
HIGH PRESSURE BUILDS ACROSS THE GREAT LAKES FOR FRIDAY. THE MODEL
TREND HAS BEEN FOR THIS HIGH TO BUILD IN WELL BRINGING DRIER AND
SOMEWHAT COOLER AIR TO THE AREA FOR FRIDAY AND PUSHING THE FRONT
SOUTH OF THE CWA. THERE IS A CHANCE THAT THE FRONT COULD BE
SLOWER...BUT WITH THE BUILDING RIDGE ACROSS THE PLAINS WOULD WANT
TO BELIEVE THAT THE HIGH WILL WIN OUT.
AFTER MILD AND SOMEWHAT HUMID CONDITIONS THURSDAY...WILL SHAVE A
FEW DEGREES OFF OF HIGHS AND BRING IN THE CLEARING FOR FRIDAY.
FRIDAY NIGHT HAS THE POTENTIAL TO BE COOL AGAIN...WITH LOWS IN THE
50S. SOME UPPER 40S NOT OUT OF THE QUESTION.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
DRY TO START WITH HIGH PRESSURE IN CONTROL AT THE SURFACE. THE
HIGH WILL MOVE SOUTHEAST ON MONDAY. DRY WEATHER FOR THE WEEKEND.
HOWEVER THE 12Z ECMWF WAS GIVING SOME QPF ON SUNDAY OVER NORTHWEST
OHIO. THE 00Z RUN WAS KEEPING THE QPF NORTH. WITH SO MUCH HIGH
PRESSURE AT THE SURFACE AND HIGH PRESSURE BUILDING IN ALOFT...KEPT
IT DRY.
FOR MONDAY AND MONDAY NIGHT SOME OF THE OLD MODEL RUNS HAD QPF WITH
SOME MOISTURE CATCHING THE AREA IN THE NORTHWEST FLOW. THE 00Z ECMWF
WAS STILL HINTING AT THIS. KEPT 20% POPS FROM THE PREVIOUS FORECAST.
CONFIDENCE IS LOW IN THIS WITH PLENTY OF RIDGING AND DRYING ALOFT
GOING ON.
TEMPERATURES WILL BE WARMING TO ABOVE NORMAL READINGS FOR THIS
PERIOD.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
A RIDGE WILL CONTINUE WEST TO EAST ACROSS THE FORECAST AREA
THROUGH THE TAF PERIOD.
AN AREA OF BROKEN CLOUDS AT 6000 FEET WAS MOVING ACROSS THE
REGION FOR THE EARLY MORNING HOURS. OTHERWISE THE TEMPERATURE AND DEW
POINT SPREADS WERE GETTING SMALLER. NOT EXPECTING THE IFR FOG AND
STRATUS TO BE AS WIDESPREAD AS IT WAS YESTERDAY...THE AIRMASS
DRIED OUT SOME ESPECIALLY ALOFT. MAINLY FOG IS EXPECTED. THE HRRR
MODEL WHICH DID A VERY GOOD JOB WITH THE STRATUS AND FOG MONDAY
MORNING. THIS MORNING THE HRRR MODEL IS NOT FORECASTING ANY MVFR
OR IFR STRATUS AND NO IFR VISIBILITIES. THIS SEEMS GOOD. MOST TAF
SITES EXCEPT CLE AND ERI WILL HAVE SOME FOG. THE BEST CHANCE FOR
SIGNIFICANT IFR CONDITIONS WILL BE CAK AND YNG...ELSEWHERE IFR FOG
WILL BE BRIEF. THE FOG WILL BURN OFF BY 10 AM AND THEN SOME
SCATTERED CUMULUS WILL DEVELOP AND DISSIPATE IN THE EVENING. A
LAKE BREEZE WILL OCCUR.
OUTLOOK ...NON-VFR POSSIBLE IN EARLY MORNING FOG WEDNESDAY THROUGH
THURSDAY AND IN THUNDERSTORMS THURSDAY AFTERNOON AND EVENING.
&&
.MARINE...
A RIDGE WILL CONTINUE OVER THE LAKE TODAY AND THEN START TO WEAKEN
ON WEDNESDAY. THE FLOW WILL BE MAINLY LIGHT WITH AN ONSHORE FLOW
DURING THE AFTERNOONS.
A SOUTHWEST FLOW WEDNESDAY NIGHT AND THURSDAY AHEAD OF A COLD FRONT
THAT WILL MOVE THROUGH DURING THE AFTERNOON. SPECIAL MARINE WARNINGS
FOR THUNDERSTORMS MAY BE NEEDED THURSDAY AFTERNOON. THE BIGGEST
QUESTION IS HOW STRONG WILL THE WINDS BE BEHIND THE COLD FRONT. IT
IS POSSIBLE THAT THE WINDS COULD PROMPT THE NEED FOR A SMALL CRAFT
ADVISORY FOR THURSDAY EVENING THROUGH DAYBREAK FRIDAY. THIS WILL
HAVE TO BE MONITORED.
HIGH PRESSURE WILL THEN BUILD OVER THE LAKE ON FRIDAY AND CONTINUE
OVER THE EASTERN LAKES THROUGH MUCH OF THE WEEKEND. THE FLOW WILL BE
NORTHEAST AT TIMES. IT DOES NOT LOOK LIKE THE WINDS WILL BE STRONG
ENOUGH TO NEED A SMALL CRAFT ADVISORY.
THE HIGH WILL MOVE EAST FOR EARLY NEXT WEEK WITH A SOUTHWEST FLOW ON
THE LAKE.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...OUDEMAN
NEAR TERM...OUDEMAN
SHORT TERM...OUDEMAN
LONG TERM...KIELTYKA
AVIATION...KIELTYKA
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
203 AM EDT TUE AUG 20 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH MID
WEEK WITH A WEAK COLD FRONT CROSSING THE AREA LATE THURSDAY. HIGH
PRESSURE THEN BUILDS BACK INTO THE AREA FOR THE REST OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
SKIES CLEARED OUT ACROSS THE FORECAST AREA THIS EVENING WITH
SUNSET AS DIURNAL CUMULUS DISSIPATED. MODELS AND SATELLITE IMAGERY
INDICATE SHORTWAVE TROUGH MOVING EAST ACROSS ILLINOIS WILL HEAD
OUR WAY OVERNIGHT. HOWEVER...IT APPEARS THIS FEATURE WILL CONTINUE
TO WEAKEN WITH TIME. SOME CLOUDS ASSOCIATED WITH THE FEATURE WILL
APPROACH THE FORECAST AREA TOWARD MORNING. FAIR WEATHER WILL BE
THE RULE THROUGH THE NIGHT. SO LITTLE CHANGE EXPECTED WITH THIS
PACKAGE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/...
HIGH PRESSURE WILL WEAKEN ON TUESDAY AS ANOTHER PIECE OF JET
ENERGY DIGS INTO THE UPPER LEVEL TROUGH THAT PERSISTS OVER THE
REGION. AS ANOTHER AREA OF WEAK MIDDLE LEVEL LOW PRESSURE DEVELOPS
OVER SOUTHERN OHIO IT WILL INCREASE THE INSTABILITY ACROSS THE
COUNTY WARNING AREA. THE CHANCES OF SHOWERS...MAYBE SOME
THUNDER...WILL INCREASE ACROSS THE SOUTH AND WEST WEDNESDAY
AFTERNOON THEN GRADUALLY SPREAD ACROSS THE EASTERN HALF OF THE
AREA WEDNESDAY EVENING THROUGH THE OVERNIGHT. THIS UPPER LOW MAY
CONTINUE TO KEEP LOW CHANCES OF RAIN ACROSS EASTERN OHIO AND
WESTERN PA INTO THURSDAY BUT THE UPPER LOW WELL GET A NUDGE FROM A
COLD FRONT THAT WILL ATTEMPT TO MOVE INTO NW OHIO AND SOUTHERN
ONTARIO BY THURSDAY AFTERNOON. THIS FRONT SHOULD BE SOUTH OF THE
COUNTY WARNING AREA BY FRIDAY MORNING. HOWEVER THERE IS CONCERN
THAT THE WEAKENING FRONT MAY MOVE THROUGH SLOWER THAN ANTICIPATED.
TEMPERATURES WILL LIKELY BE ABOVE AVERAGE TUESDAY INTO WEDNESDAY
BEFORE INCREASING CLOUD COVER ON THURSDAY TRIMS A COUPLE DEGREES.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
SURFACE HIGH PRESSURE WILL TAKE CONTROL ON FRIDAY WITH HIGHS NEAR
SEASONAL LEVELS.
THE MODELS DIFFER ON SOME OF THE WEAKER FEATURES DURING THE PERIOD.
IN GENERAL...THERE SHOULD BE A SMALL THREAT FOR SHRA AND TSRA AS
WEAK UPPER TROFS DIVE SE ACROSS THE LERI AREA WHILE A SURFACE
BOUNDARY MAY SET UP NEAR LERI. INITIALLY THE SURFACE HIGH WILL
STILL BE IN CONTROL ON SAT WITH FAIRLY DRY AIR SO WILL HOLD OFF
ANY THREAT FOR PRECIP ON SAT THEN SLOWLY ALLOW THE POP TO INCREASE
SOME SUN INTO MON AS INCREASING MOISTURE SHOULD RETURN TO THE AREA.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
A RIDGE WILL CONTINUE WEST TO EAST ACROSS THE FORECAST AREA
THROUGH THE TAF PERIOD.
AN AREA OF BROKEN CLOUDS AT 6000 FEET WAS MOVING ACROSS THE
REGION FOR THE EARLY MORNING HOURS. OTHERWISE THE TEMPERATURE AND DEW
POINT SPREADS WERE GETTING SMALLER. NOT EXPECTING THE IFR FOG AND
STRATUS TO BE AS WIDESPREAD AS IT WAS YESTERDAY...THE AIRMASS
DRIED OUT SOME ESPECIALLY ALOFT. MAINLY FOG IS EXPECTED. THE HRRR
MODEL WHICH DID A VERY GOOD JOB WITH THE STRATUS AND FOG MONDAY
MORNING. THIS MORNING THE HRRR MODEL IS NOT FORECASTING ANY MVFR
OR IFR STRATUS AND NO IFR VISIBILITIES. THIS SEEMS GOOD. MOST TAF
SITES EXCEPT CLE AND ERI WILL HAVE SOME FOG. THE BEST CHANCE FOR
SIGNIFICANT IFR CONDITIONS WILL BE CAK AND YNG...ELSEWHERE IFR FOG
WILL BE BRIEF. THE FOG WILL BURN OFF BY 10 AM AND THEN SOME
SCATTERED CUMULUS WILL DEVELOP AND DISSIPATE IN THE EVENING. A
LAKE BREEZE WILL OCCUR.
OUTLOOK ...NON-VFR POSSIBLE IN EARLY MORNING FOG WEDNESDAY THROUGH
THURSDAY AND IN THUNDERSTORMS THURSDAY AFTERNOON AND EVENING.
&&
.MARINE...
HIGH PRESSURE IN CONTROL OF THE REGION WILL KEEP WINDS MAINLY UNDER
15 KNOTS THRU SAT. A COLD FRONT CROSSING THE LAKE THU MAY BRIEFLY
KICK WINDS UP TO 10 TO 20 KNOTS OUT OF THE SW AHEAD OF THE FRONT
THEN WINDS TURN NORTH AND SHOULD SETTLE BACK INTO A 5 TO 15 KNOT
RANGE BY FRI BEFORE TURNING EAST FOR SAT.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MULLEN
NEAR TERM...LOMBARDY
SHORT TERM...MULLEN
LONG TERM...ADAMS
AVIATION...KIELTYKA
MARINE...ADAMS
AREA FORECAST DISCUSSION
NWS PORTLAND OR
819 PM PDT WED AUG 21 2013
.SYNOPSIS...AN UPPER LEVEL LOW PRESSURE OFF THE CALIFORNIA COAST WILL
BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS MAINLY THE
CENTRAL OREGON CASCADES THURSDAY. AS THE SYSTEM LIFTS NORTHEAST OF
THE AREA...EXPECT MARINE AIR TO SPREAD IN BEHIND IT...BRINGING COOLER
TEMPERATURES AND AN INCREASE IN MORNING CLOUDS TO NORTHWEST OREGON
AND SOUTHWEST WASHINGTON FRIDAY AND SATURDAY. AN UPPER LEVEL
TROUGH WILL LINGER OFF THE COAST INTO EARLY NEXT WEEK...KEEPING
TEMPERATURES NEAR NORMAL WITH A SLIGHT CHANCE OF SHOWERS ALONG MAINLY
THE COAST AND CASCADES.
&&
.EVENING UPDATE...SHOWERS AND THUNDERSTORMS REMAIN LARGELY CONFINED
TO A 850-500MB THETAE RIDGE AXIS DRAPED ALONG THE CALIFORNIA/OREGON
BORDER THIS EVENING. A LOOP OF THE DOPPLER RADAR MOSAIC DOES SHOW A
GRAVITY WAVE FEATURE INITIATING CONVECTION BETWEEN SPRAGUE RIVER AND
PAISLEY OREGON AS IT PROPAGATES NORTHWARD FROM A DECAYING
THUNDERSTORM COMPLEX THAT WAS OVER NORTHEASTERN CALIFORNIA EARLIER
THIS EVENING. IT SEEMS LIKELY THIS GRAVITY WAVE WILL LIKELY WEAKEN
WITH TIME WHILE STABILIZING THE ATMOSPHERE IN ITS WAKE.
NONETHELESS...THE RAP CAPTURES THE AFOREMENTIONED THETAE RIDGE
WELL...PIVOTING THE WESTERN END OF IT NORTHWARD SO THAT IT CLIPS
SOUTHEASTERN LANE COUNTY TOWARDS DAYBREAK. THIS WILL RESULT IN AT
LEAST A SMALL CHANCE FOR A SHOWER OR THUNDERSTORM TO CLIP THE LANE
COUNTY CASCADES DURING THIS TIME. AS A RESULT...POPS WERE INCREASED
TO AT LEAST INCLUDE A SLIGHT CHANCE TO CHANCE MENTION OF SHOWERS AND
THUNDERSTORMS NEAR WILLAMETTE PASS FOR LATE TONIGHT AND THURSDAY
MORNING. ALSO...GIVEN THE LARGE SHIELD OF CLOUDS TO OUR SOUTH AND
THE NORTHWARD PROGRESSION IT WILL TAKE OVERNIGHT...SKY COVER WAS
ALSO INCREASED...PARTICULARLY SOUTH OF SALEM.
GIVEN THE SMOKE FROM THE GOVERNMENT FLATS COMPLEX HAS DRIFTED INTO
THE HOOD RIVER VALLEY THIS AFTERNOON AND EVENING...AREAS OF SMOKE
WAS ADDED TO THE FORECAST THROUGH THURSDAY MORNING. WESTERLY WINDS
SHOULD INCREASE THURSDAY AFTERNOON...BLOWING MUCH OF THE SMOKE FROM
THE GOVERNMENT FLATS COMPLEX EAST OF OUR CWA.
OTHERWISE...THE REST OF THE FORECAST APPEARS ON TRACK WITH CONVECTION
LIKELY FIRING OVER THE SISKIYOUS DURING THE EARLY AFTERNOON
HOURS...PROGRESSING NORTH-NORTHEASTWARD TOWARDS OUR LANE COUNTY
CASCADES LATE IN THE AFTERNOON. THERE IS A GOOD CHANCE THAT AT LEAST
SOME THUNDERSTORM ACTIVITY WILL CLIP OUR CENTRAL OREGON CASCADES SO
THE HIGH CHANCE POPS WERE LEFT IN TACT. THE BEST 0-6KM SHEAR VALUES
LOOK TO REMAIN PREDOMINANTLY EAST OF OUR CWA SO SEVERE THUNDERSTORMS
SEEM UNLIKELY AT THIS POINT. THE RED FLAG WARNING FOR ABUNDANT
LIGHTNING AND SUFFICIENTLY DRY FUELS REMAINS IN EFFECT FOR THE
WILLAMETTE NATIONAL FOREST FOR PRIMARILY THURSDAY AFTERNOON AND
EVENING GIVEN THE AFOREMENTIONED SCENARIO LIKELY PLAYING OUT. /NEUMAN
.SHORT TERM...PREVIOUS DISCUSSION BELOW...THE UPPER LOW OFF THE
CENTRAL CA COAST WAS SEEN SLOWLY LIFTING N IN WATER VAPOR IMAGERY
THIS AFTERNOON. AS INDICATED BY MODELS...EXPECT THE NORTHWARD
MOVEMENT OF THE LOW TO ACCELERATE AS IT GETS CAUGHT UP IN THE SW FLOW
AHEAD OF THE LARGER NORTHERN STREAM TROUGH OUT NEAR 140W. DIURNAL
CONVECTION HAD BEGUN TO FIRE IN NORTHERN CA INTO SE OREGON EARLY THIS
AFTERNOON IN THE AREA OF BEST DIFFLUENCE ALOFT NE OF THE LOW
CENTER...WHICH ALSO FITS WELL WITH BEST MODEL DIAGNOSED AREAS OF
INSTABILITY. WILL KEEP A SLIGHT CHANCE OF THUNDERSTORMS IN THIS
EVENING IN THE CENTRAL OREGON CASCADES ON THE FRINGES OF THE FAVORED
CONVECTIVE AREA...BUT WITH THE LOW EXPECTED TO LIFT N THEN NE IN THE
NEXT 36 HOURS...WILL SEE THE THUNDERSTORM THREAT PEAK LATE THU OVER
THE SE HALF OF THE FORECAST AREA.
SURFACE ANALYSIS SHOWED A THERMAL INDUCED TROUGH EXTENDING ROUGHLY N
TO S THROUGH THE WILLAMETTE VALLEY WED AFTERNOON. TROUGH IS NOT
LIKELY TO MOVE A LOT THIS EVENING...BUT SHOULD SHIFT E OF THE
CASCADES THU TURNING THE FLOW ONSHORE. WITH ONSHORE FLOW MOSTLY
LIMITED TO THE COAST TONIGHT...MARINE CLOUDS OR FOG ARE LIKELY TO
ALSO BE LIMITED TO COAST LATE TONIGHT AND THU MORNING. WITH THE
PASSAGE OF THE UPPER LOW OFF TO THE NE FRI...ONSHORE FLOW WILL
STRENGTHEN FRI AND SAT. THIS SHOULD BRING IN A DEEPER MARINE AIR
MASS...RESULTING IN MORE CLOUDS AND COOLER DAYTIME TEMPS. WILL ADD A
THREAT OF DRIZZLE TO THE COAST FRI MORNING...THEN EXPAND THE CHANCES
FOR DRIZZLE SAT AS MARINE AIR MASS DEEPENS AND A SHORTWAVE TROUGH
EJECTS OUT OF THE OFFSHORE TROUGH.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...
THE PAC NW WILL REMAIN UNDER THE INFLUENCE OF PERSISTENT UPPER LEVEL
TROUGHING THROUGH THE EXTENDED PERIOD. THE BROAD UPPER LEVEL TROUGH
OVER THE NE PAC WILL BRING PERIODIC WEAK IMPULSES AROUND THE BASE OF
THE TROUGH...KEEPING CONTINUOUS ONSHORE FLOW OVER THE REGION. THIS
WILL LIKELY RESULT IN CLOUDS REMAINING LOCKED IN AT THE COAST...WITH
GOOD MARINE PUSHES BRINGING CLOUDS INLAND DURING THE OVERNIGHT AND
MORNING HOURS. THERE MAY BE SOME PERIODIC DRIZZLE OR SHOWERS MAINLY
AT THE COAST...ESPECIALLY WHEN THE WEAK UPPER LEVEL SHORTWAVES MOVE
THROUGH. THERE WILL ALSO BE CHANCES FOR SHOWERS IN THE
CASCADES...MAINLY ALONG AND EAST OF THE CREST DUE TO THE WESTERLY
FLOW COMPONENT. TEMPERATURES WILL RUN A FEW DEG BELOW NORMAL DUE TO
THE INFLUENCE OF THE COOL MARINE AIRMASS. PYLE
&&
.AVIATION...WITH NO LOW CLOUDS CURRENTLY SEEN ON
SATELLITE IMAGERY OVER THE COASTAL WATERS...EXPECT THE COAST WILL
REMAIN VFR FOR MOST OF THE NIGHT. HOWEVER...LOCAL MVFR OR IFR
CONDITIONS IN FOG AND STRATUS WILL LIKELY TAKE HOLD NEAR 12Z
TOMORROW MORNING AS LOW LEVEL ONSHORE FLOW INCREASES. LOW LEVEL
CLOUDS MAY REMAIN RIGHT ALONG THE SHORE FOR MUCH OF THE DAY...SO
COASTAL TAF SITES WILL LIKELY SEE PERIODS OF MVFR OR IFR
CONDITIONS AT TIMES THROUGH THE DAY. EXPECT VFR CONDITIONS WILL
CONTINUE FOR INLAND SITES OVER THE NEXT 24 HOURS.
HOWEVER...SHOWERS AND THUNDERSTORMS WILL BE A POSSIBILITY IN
SOUTHERN PORTIONS OF THE FCST AREA TOMORROW AFTERNOON AND EVENING.
KPDX AND APPROACHES...VFR CONDITIONS EXPECTED FOR THE
NEXT 24 HOURS. PYLE
&&
.MARINE...MARGINALLY GUSTY N TO NW WINDS WILL CONTINUE OVERNIGHT
UNDER
HIGH PRES OVER NE PAC AND THERMAL LOW PRES OVER N CALIF. THE
NEARSHORE OBSERVATION SITES ARE NOT SHOWING MUCH WIND THIS
EVENING...BUT THE FCST MODELS CONTINUE TO INDICATE WIND GUSTS IN
THE 20 TO 25 KT RANGE OVERNIGHT FOR THE OUTER WATERS. SO WILL
MAINTAIN A SMALL CRAFT ADVISORY FOR WINDS THROUGH EARLY TOMORROW
MORNING FOR AREAS BEYOND 10 NM OFFSHORE. WINDS STILL LOOK ON TRACK TO
RELAX TOMORROW MORNING AS AN UPPER LEVEL LOW PRESSURE APPROACHES
THE REGION.
SEAS SHOULD GENERALLY REMAIN 5 TO 6 FT THROUGH TOMORROW...THEN
DROP BELOW 5 FT ON FRI. SEAS SHOULD REMAIN BELOW 5 FT THROUGH THE
WEEKEND. PYLE
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING FROM 1 PM THURSDAY TO 2 AM PDT FRIDAY FOR ZONE
608.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 8 AM PDT THURSDAY FOR
WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR FROM 10
TO 60 NM-WATERS FROM CASCADE HEAD TO FLORENCE OR FROM 10 TO
60 NM.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
707 AM EDT TUE AUG 20 2013
.SYNOPSIS...
HIGH PRESSURE OFF OF THE EAST COAST WILL CONTROL THE WEATHER
ACROSS PA THROUGH MIDWEEK. A COLD FRONT WILL PUSH THROUGH THE
REGION LATE THURSDAY OR EARLY FRIDAY. CANADIAN HIGH PRESSURE WILL
THEN BUILD SOUTHEAST INTO PENNSYLVANIA NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MODIS 11-3.7UM IMAGERY SHOWING WIDESPREAD VALLEY FOG ACROSS
CENTRAL PA EARLY THIS AM. MANY LOCATIONS AOB 1/4SM VSBY AT
09Z...SO HAVE ISSUED A DENSE FOG ADVISORY THRU 13Z. 3KM HRRR SFC
RH SUGGESTS THE FOG WILL BURN OFF IN MANY LOCATIONS BY ARND
12Z...BUT WILL LIKELY LINGER IN A FEW LOCATIONS UNTIL 14Z.
LARGE SCALE SUBSIDENCE UNDER HIGH PRESSURE SHOULD ENSURE ABUNDANT
SUNSHINE LATER TODAY WITH A RETURN TO MORE SUMMER-LIKE CONDITIONS.
ENS MEAN 8H TEMPS NR 16C SHOULD SUPPORT HIGH TEMPS IN THE 80S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
CLEAR SKIES AND A CALM WIND UNDER SFC HIGH SHOULD RESULT IN LATE
NIGHT VALLEY FOG AGAIN TONIGHT. HOWEVER...RH/S WILL BE MUCH LOWER
GOING INTO THE EVENING HRS...SO EXPECT THE DENSE FOG TO BE ISOLATED
TO THE DEEP RIVER/STREAM VALLEYS OF THE ALLEGHENIES.
SFC HIGH WILL RETREAT OFF THE E COAST ON WED AND CUT-OFF UPPER
LOW...CURRENTLY OVR ILLINOIS...WILL BE LIFTING UP THE OHIO VALLEY
TOWARD PA. LG SCALE FORCING AND INCREASINGLY MOIST SOUTHERLY FLOW
AHEAD OF THIS FEATURE COULD RESULT IN A FEW LATE DAY SHRA/TSRA
ACROSS THE SOUTHERN COUNTIES. TEMPS/HUMIDITY WILL CONTINUE TO
CREEP UP...WITH AFTN READINGS LIKELY RANGING FROM THE L80S OVR THE
ALLEGHENY PLATEAU...TO THE U80S IN THE SUSQ VALLEY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
LITTLE SPREAD NOTED AMONG 00Z MED RANGE GUIDANCE...ALL OF WHICH
SHOW UPPER LOW OPENING UP AS IT LIFTS INTO PA WED NIGHT AND
THURSDAY. THIS WEAKENING SHORTWAVE THEN MERGES WITH MAIN BRANCH OF
JET AS IT AND ASSOC COLD FRONT DIVE SE INTO PA LATE THURSDAY. BASED
ON THIS SCENARIO...HAVE INTRODUCED A CHC OF SHRA/TSRA WED NITE
ACROSS THE SOUTH AND THE ENTIRE AREA BY THU PM.
WIDESPREAD AGREEMENT AMONG MED RANGE GUIDANCE THAT CENTRAL PA WILL
SEE A RETURN TO COOLER/LESS HUMID CONDS FRI-SUN...AS CANADIAN
HIGH PRES AND ASSOC NEGATIVE PWAT ANOMALIES BUILD SE INTO PA. HAVE
REDUCED MIN TEMPS NEXT WEEKEND GIVEN THE POTENTIAL OF RAD COOLING.
HOWEVER...ECMWF ENS MEAN 8H TEMPS NR 12C SHOULD RESULT IN DAYTIME
HIGHS NR LATE AUGUST NORMALS. BY LATE SUNDAY OR MONDAY...SFC HIGH
WILL LIKELY PASS SOUTH OF PA...BRINGING RETURN SW FLOW OF
WARMER/MORE HUMID CONDS AND THE CHC OF CONVECTION ON EASTERN
PERIPHERY OF BUILDING UPPER LVL RIDGE OVR THE MIDWEST.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
HIGH PRESSURE WILL CONTROL THE WEATHER ACROSS PA THIS MIDWEEK.
WIDESPREAD DENSE VALLEY FOG ACROSS CENTRAL PA EARLY THIS MORNING
AS STRONG RADIATIONAL COOLING BROUGHT TEMPS DOWN TO THE DEWPOINTS.
AN AREA FROM KUNV-KIPT REMAINED MVFR WHILE REMAINDER OF TAF SITES
SLIPPED TO VLIFR. THE FOG /ASSOCIATED LOW CLOUDS WHEN IT LIFTS/ WILL
BE STUBBORN FOR ANOTHER HOUR OR TWO /13-14Z/ BEFORE RAPID
IMPROVEMENT BRINGS CONDITIONS UP TO VFR AREAWIDE. WINDS WILL BE
LIGHT FROM THE WEST AND LARGE SCALE SUBSIDENCE WILL KEEP CLOUDS TO
A MINIMUM.
FOG RETURNS AGAIN LATE TONIGHT...BUT WITH RH LOWER THIS EVE FOG
WILL NOT BE AS WIDESPREAD AND THICK AS THIS MORNING /CONFINED
MAINLY TO THE VALLEYS/...BEFORE GIVING WAY TO ANOTHER WIDESPREAD
VFR DAY ON WED.
OUTLOOK...
WED-THU...VFR.
FRI...MVFR WITH SCT SHRA/TSRA.
SAT...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR PAZ004>006-
010>012-017>019-024>028-033>037-041-042-045-046-049>053-
056>059-063>066.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD
AVIATION...RXR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
601 AM EDT TUE AUG 20 2013
.SYNOPSIS...
HIGH PRESSURE OFF OF THE EAST COAST WILL CONTROL THE WEATHER
ACROSS PA THROUGH MIDWEEK. A COLD FRONT WILL PUSH THROUGH THE
REGION LATE THURSDAY OR EARLY FRIDAY. CANADIAN HIGH PRESSURE WILL
THEN BUILD SOUTHEAST INTO PENNSYLVANIA NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MODIS 11-3.7UM IMAGERY SHOWING WIDESPREAD VALLEY FOG ACROSS
CENTRAL PA EARLY THIS AM. MANY LOCATIONS AOB 1/4SM VSBY AT
09Z...SO HAVE ISSUED A DENSE FOG ADVISORY THRU 13Z. 3KM HRRR SFC
RH SUGGESTS THE FOG WILL BURN OFF IN MANY LOCATIONS BY ARND
12Z...BUT WILL LIKELY LINGER IN A FEW LOCATIONS UNTIL 14Z.
LARGE SCALE SUBSIDENCE UNDER HIGH PRESSURE SHOULD ENSURE ABUNDANT
SUNSHINE LATER TODAY WITH A RETURN TO MORE SUMMER-LIKE CONDITIONS.
ENS MEAN 8H TEMPS NR 16C SHOULD SUPPORT HIGH TEMPS IN THE 80S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
CLEAR SKIES AND A CALM WIND UNDER SFC HIGH SHOULD RESULT IN LATE
NIGHT VALLEY FOG AGAIN TONIGHT. HOWEVER...RH/S WILL BE MUCH LOWER
GOING INTO THE EVENING HRS...SO EXPECT THE DENSE FOG TO BE ISOLATED
TO THE DEEP RIVER/STREAM VALLEYS OF THE ALLEGHENIES.
SFC HIGH WILL RETREAT OFF THE E COAST ON WED AND CUT-OFF UPPER
LOW...CURRENTLY OVR ILLINOIS...WILL BE LIFTING UP THE OHIO VALLEY
TOWARD PA. LG SCALE FORCING AND INCREASINGLY MOIST SOUTHERLY FLOW
AHEAD OF THIS FEATURE COULD RESULT IN A FEW LATE DAY SHRA/TSRA
ACROSS THE SOUTHERN COUNTIES. TEMPS/HUMIDITY WILL CONTINUE TO
CREEP UP...WITH AFTN READINGS LIKELY RANGING FROM THE L80S OVR THE
ALLEGHENY PLATEAU...TO THE U80S IN THE SUSQ VALLEY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
LITTLE SPREAD NOTED AMONG 00Z MED RANGE GUIDANCE...ALL OF WHICH
SHOW UPPER LOW OPENING UP AS IT LIFTS INTO PA WED NIGHT AND
THURSDAY. THIS WEAKENING SHORTWAVE THEN MERGES WITH MAIN BRANCH OF
JET AS IT AND ASSOC COLD FRONT DIVE SE INTO PA LATE THURSDAY. BASED
ON THIS SCENARIO...HAVE INTRODUCED A CHC OF SHRA/TSRA WED NITE
ACROSS THE SOUTH AND THE ENTIRE AREA BY THU PM.
WIDESPREAD AGREEMENT AMONG MED RANGE GUIDANCE THAT CENTRAL PA WILL
SEE A RETURN TO COOLER/LESS HUMID CONDS FRI-SUN...AS CANADIAN
HIGH PRES AND ASSOC NEGATIVE PWAT ANOMALIES BUILD SE INTO PA. HAVE
REDUCED MIN TEMPS NEXT WEEKEND GIVEN THE POTENTIAL OF RAD COOLING.
HOWEVER...ECMWF ENS MEAN 8H TEMPS NR 12C SHOULD RESULT IN DAYTIME
HIGHS NR LATE AUGUST NORMALS. BY LATE SUNDAY OR MONDAY...SFC HIGH
WILL LIKELY PASS SOUTH OF PA...BRINGING RETURN SW FLOW OF
WARMER/MORE HUMID CONDS AND THE CHC OF CONVECTION ON EASTERN
PERIPHERY OF BUILDING UPPER LVL RIDGE OVR THE MIDWEST.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
HIGH PRESSURE CENTERED NEAR BERMUDA WILL CONTROL THE WEATHER
ACROSS PA THIS MIDWEEK.
DWPT DEPRESSIONS RUNNING BTWN 0-3F ACROSS CENTRAL PA AND
ADDITIONAL RADIATIONAL COOLING WILL RESULT IN WIDESPREAD FOG EARLY
THIS MORNING. SOME OF THE FOG WILL BE DENSE...ESP IN THE DEEP
VALLEYS OF THE ALLEGHENIES AND WHERE THERE WAS RAINFALL YESTERDAY.
THE FOG AND ASSOCIATED LOW CLOUDS WILL BEGIN TO BURN-OFF SHORTLY
AFTER SUNRISE. THOUGH MVFR MAY LINGER INTO THE MID MORNING...THE
REMAINDER OF THE DAY WILL BE VFR.
FOG RETURNS FOR LATE TUE NIGHT...THOUGH NOT AS WIDESPREAD AND
THICK AS THIS MORNING.
OUTLOOK...
WED-THU...VFR.
FRI...MVFR WITH SCT SHRA/TSRA.
SAT...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR PAZ004>006-
010>012-017>019-024>028-033>037-041-042-045-046-049>053-
056>059-063>066.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD
AVIATION...RXR
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1033 PM CDT WED AUG 21 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.UPDATE...
ISSUED AT 938 PM CDT WED AUG 21 2013
SVR THREAT HAS ENDED. LINGERING SHRA SHOULD EXIT E-C WI WITHIN THE
NEXT HR OR SO. WAS HOLDING SLGT CHC POPS BACK ACRS THE SRN PART OF
THE FCST AREA IN CASE SOME SHRA DEVELOPED BACK TO THE W...BUT THE
CHC FOR THAT HAPPENING SEEMS TO BE WANING...SO WL PROBABLY JUST BE
DRY FOR THE REST OF THE NGT.
FOG HAS BEGUN TO DEVELOP ALONG THE WRN EDGE OF THE CLEARING
WORKING IN FM THE W. GIVEN THE WIDESPREAD SIG RAINS THAT FELL ACRS
THE AREA AND THE FACT THAT LOW-LEVEL MOISTURE HASN/T BEEN STRIPPED
OUT YET...EXPECT THE FOG TO EXPAND EWD SOME DURING THE NGT. BUT
CONDITIONS WL START TO BECOME LESS FAVORABLE FOR THE FOG LATER
TNGT AS SFC PRESSURE GRADIENT TIGHTENS A BIT. WINDS ARND 850 MB WL
ALSO TURN NW AND CAA WL COMMENCE. THAT WL PROMOTE SOME MIXING AND
SHOULD PREVENT THE FG FROM GETTING OUT OF HAND.
&&
.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 206 PM CDT WED AUG 21 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A STRONG COLD
FRONT MOVING OVER THE FAR WESTERN UPPER PENINSULA AND NORTHWEST
WISCONSIN EARLY THIS AFTERNOON. MOISTURE CONVERGENCE ALONG THE
FRONT LOOKS GOOD...AND ML CAPES ARE BUILDING BETWEEN 2K-3K J/KG
AHEAD OF THE BOUNDARY. RETURNS ON RADAR ARE PICKING UP ALONG THE
FRONT AS INHIBITION ERODES BELOW 50 J/KG. WITH 0-6KM BULK SHEAR
VALUES AROUND 25-30 KTS...CONDITIONS REMAIN CONDUCIVE FOR SEVERE
THUNDERSTORMS TO DEVELOP LATER THIS AFTERNOON. THE NSSL WRF SEEMS
TO BE DOING THE BEST OUT OF THE MESOMODELS...AND SHOWS CONVECTION
RAMPING UP IN A LINEAR FASHION BETWEEN 19-21Z. BY THE END OF THIS
PERIOD...CONVECTION WILL BE MOVING INTO N-C WISCONSIN BEFORE
PROGRESSING INTO CENTRAL AND NORTHEAST WISCONSIN BY 00Z. STILL
LOOKING AT MULTI-CELLS AND SMALL BOWING SEGMENTS AS THE STORM
MODE...WHICH WILL BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS AND
LARGE HAIL. ANOTHER WRINKLE IS THE WEAK LITTLE SHORTWAVE OVER
SOUTHERN MINNESOTA. THE RUC TAKES THIS FEATURE INTO SW WISCONSIN
THIS EVENING...AND NOT SURE HOW MUCH THIS WILL IMPACT THUNDERSTORMS
ALONG THE FRONT. SEVERE WEATHER IS THE OBVIOUS FORECAST CONCERN.
TONIGHT...SHORTWAVE TROUGH MOVING ACROSS ONTARIO WILL PUSH A COLD
FRONT SOUTHEAST ACROSS CENTRAL AND NORTHEAST WISCONSIN THIS
EVENING. SOUTH SOUTHWEST FLOW AHEAD OF THE FRONT WITH PWATS UPWARDS
OF 1.75 INCHES WILL PREVENT TEMPS FROM FALLING TOO FAST THIS
EVENING...WHICH SHOULD PROLONG THE SEVERE THREAT UNTIL THE FRONT
CLEARS THE AREA. BECAUSE INSTABILITY WILL BE DECREASING...THE LARGE
HAIL THREAT WILL DIMINISH AS WELL THROUGH THE EVENING. BUT THINK
THERE IS ENOUGH POTENTIAL FOR LARGE HAIL AND DAMAGING WINDS TO REACH
EAST-CENTRAL AND NORTHEAST WISCONSIN. PRECIP WILL BE EXITING
EAST-CENTRAL EARLY OVERNIGHT AS MUCH DRIER AIR WILL FILTER SOUTH
BEHIND THE FRONT. TEMPS WILL BE A LITTLE SLOWER TO COOL OFF...BUT
LOWS SHOULD STILL FALL INTO THE LOWER OR MIDDLE 50S NORTH...BUT HANG
IN THE MID 60S SOUTH.
THURSDAY...THE COLD FRONT WILL MOVE TO THE SOUTHERN GREAT LAKES BY
THE START OF THE PERIOD WHILE CANADIAN HIGH PRESSURE WILL BE
BUILDING SOUTHEAST FROM THE NORTHERN PLAINS. THIS AIRMASS WILL BE
COOLER AND SIGNIFICANTLY LESS HUMID THAN THE ONE IT REPLACED. UNDER
PLENTY OF SUN...HIGH TEMPS WILL REACH FROM THE MID 70S NORTH TO THE
LOW 80S SOUTH.
.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 206 PM CDT WED AUG 21 2013
PATTERN TO BECOME RATHER AMPLIFIED AS MOVE THROUGH THIS PERIOD AS
UPPER RIDGE BUILDS OVER THE CENTRAL US...INTO WESTERN LAKES.
MODELS HAVE GOOD CONTINUITY IN BIG PICTURE...BUT TEND TO DIFFER IN
CONVECTIVE DETAILS SUN ONWARD. MAIN ISSUE WILL BE HEAT LATER
PERIODS. ILL-DEFINED WARM FRONT EXPECTED TO LIFT NORTH
INTO/THROUGH STATE SUN. 850 MB TEMPS EXPECTED TO WARM SAT ONWARD
HITTING 20C EARLY IN WORK WEEK. IF MODELS SOUNDINGS
CORRECT...WOULD MIX UP TO THAT LEVEL YIELDING TEMPS AROUND 90 NEXT
MON THROUGH WED. QUESTION IS EFFECTS OF CLOUDS AND PCPN. LIKELY
TO BE ON EDGE OF CAP WITH CONVECTION NEAR OR OVER REGION. HAVE
TRENDED HIGHER POPS OVER NORTHERN WI WHERE ECMWF LINGERS FRONT.
HAVE USED BEST PERFORMING BLEND FOR TEMPS...BUMPING THEM UP A
DEGREE TO LESSEN CLIMO BIAS.
EARLY PERIODS/THU NIGHT INTO FRI NIGHT/PLEASANT WITH COOLER HIGH
PRESSURE AT THE SURFACE OVER REGION. CLEAR SKIES AND DRY
CONDITIONS TO LEAD TO COOLER NIGHTS AND MILD DAYS. HAVE SLOWED
APPROACH OF PCPN SAT GIVEN MODEL TRENDS.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1030 PM CDT WED AUG 21 2013
HARD TO GET A GOOD HANDLE ON THE FOG SITN TNGT. ON ONE HAND...HIGH SFC
DWPTS HAVENT BEEN SCOURED OUT OF THE AREA AND WE/VE NOW HAD SIG
RAIN. ON THE OTHER HAND...WINDS ABV THE SFC SHOULD PICK UP A
LITTLE FM THE NW AND GENERATE SOME WK CAA LATER TNGT. THAT WL
PROMOTE MIXING...AND WORK AGAINST DENSE FOG. INITIAL PLAN IS TO GO
WITH RATHER ATYPICAL TEMPORAL DISTRIBUTION OF THE FG...WITH POOR
CONDITIONS DURING THE MIDDLE OF THE NGT AND SOME IMPROVEMENT
TOWARD DAYBREAK. BUT CONFIDENCE IN THAT HAPPENINGS IS NOT GREAT.
ONCE ANY FG BURNS OFF TOMORROW...VFR CONDITIONS EXPECTED FOR THE
REST OF THE DAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE.........SKOWRONSKI
SHORT TERM.....MPC
LONG TERM......TE
AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
605 PM CDT WED AUG 21 2013
NEW INFORMATION ADDED TO UPDATE SECTION AND ADDED DISCUSSION FOR
00Z TAF ISSUANCE
.UPDATE...
ISSUED AT 600 PM CDT WED AUG 21 2013
TSTSMS CONT TO GRADUALLY EXPAND IN COVERAGE AS THE LINE BUILDS SWD
ACRS THE AREA. CONFIRMED REPORTS OF SVR RATHER SPARSE THUS
FAR...BUT RADAR SIGNATURES INDICATED IT IS VERY LIKELY DAMAGING
WINDS OCCURRED WITHIN THE PAST 30-45 MINUTES OVER FOREST CO.
SEE NO REASON SVR THREAT WON/T SURGE SEWD ACRS THE REST OF THE
AREA DURING THE EVENING.
THE SVR THREAT WL END WITH THE PASSAGE OF THE MAIN LINE OF
STORMS...SO PLAN TO DROP COUNTIES FM THE WATCH ONCE THE LINE SAGS
THROUGH THEIR AREA.
&&
.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 206 PM CDT WED AUG 21 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A STRONG COLD
FRONT MOVING OVER THE FAR WESTERN UPPER PENINSULA AND NORTHWEST
WISCONSIN EARLY THIS AFTERNOON. MOISTURE CONVERGENCE ALONG THE
FRONT LOOKS GOOD...AND ML CAPES ARE BUILDING BETWEEN 2K-3K J/KG
AHEAD OF THE BOUNDARY. RETURNS ON RADAR ARE PICKING UP ALONG THE
FRONT AS INHIBITION ERODES BELOW 50 J/KG. WITH 0-6KM BULK SHEAR
VALUES AROUND 25-30 KTS...CONDITIONS REMAIN CONDUCIVE FOR SEVERE
THUNDERSTORMS TO DEVELOP LATER THIS AFTERNOON. THE NSSL WRF SEEMS
TO BE DOING THE BEST OUT OF THE MESOMODELS...AND SHOWS CONVECTION
RAMPING UP IN A LINEAR FASHION BETWEEN 19-21Z. BY THE END OF THIS
PERIOD...CONVECTION WILL BE MOVING INTO N-C WISCONSIN BEFORE
PROGRESSING INTO CENTRAL AND NORTHEAST WISCONSIN BY 00Z. STILL
LOOKING AT MULTI-CELLS AND SMALL BOWING SEGMENTS AS THE STORM
MODE...WHICH WILL BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS AND
LARGE HAIL. ANOTHER WRINKLE IS THE WEAK LITTLE SHORTWAVE OVER
SOUTHERN MINNESOTA. THE RUC TAKES THIS FEATURE INTO SW WISCONSIN
THIS EVENING...AND NOT SURE HOW MUCH THIS WILL IMPACT THUNDERSTORMS
ALONG THE FRONT. SEVERE WEATHER IS THE OBVIOUS FORECAST CONCERN.
TONIGHT...SHORTWAVE TROUGH MOVING ACROSS ONTARIO WILL PUSH A COLD
FRONT SOUTHEAST ACROSS CENTRAL AND NORTHEAST WISCONSIN THIS
EVENING. SOUTH SOUTHWEST FLOW AHEAD OF THE FRONT WITH PWATS UPWARDS
OF 1.75 INCHES WILL PREVENT TEMPS FROM FALLING TOO FAST THIS
EVENING...WHICH SHOULD PROLONG THE SEVERE THREAT UNTIL THE FRONT
CLEARS THE AREA. BECAUSE INSTABILITY WILL BE DECREASING...THE LARGE
HAIL THREAT WILL DIMINISH AS WELL THROUGH THE EVENING. BUT THINK
THERE IS ENOUGH POTENTIAL FOR LARGE HAIL AND DAMAGING WINDS TO REACH
EAST-CENTRAL AND NORTHEAST WISCONSIN. PRECIP WILL BE EXITING
EAST-CENTRAL EARLY OVERNIGHT AS MUCH DRIER AIR WILL FILTER SOUTH
BEHIND THE FRONT. TEMPS WILL BE A LITTLE SLOWER TO COOL OFF...BUT
LOWS SHOULD STILL FALL INTO THE LOWER OR MIDDLE 50S NORTH...BUT HANG
IN THE MID 60S SOUTH.
THURSDAY...THE COLD FRONT WILL MOVE TO THE SOUTHERN GREAT LAKES BY
THE START OF THE PERIOD WHILE CANADIAN HIGH PRESSURE WILL BE
BUILDING SOUTHEAST FROM THE NORTHERN PLAINS. THIS AIRMASS WILL BE
COOLER AND SIGNIFICANTLY LESS HUMID THAN THE ONE IT REPLACED. UNDER
PLENTY OF SUN...HIGH TEMPS WILL REACH FROM THE MID 70S NORTH TO THE
LOW 80S SOUTH.
.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 206 PM CDT WED AUG 21 2013
PATTERN TO BECOME RATHER AMPLIFIED AS MOVE THROUGH THIS PERIOD AS
UPPER RIDGE BUILDS OVER THE CENTRAL US...INTO WESTERN LAKES.
MODELS HAVE GOOD CONTINUITY IN BIG PICTURE...BUT TEND TO DIFFER IN
CONVECTIVE DETAILS SUN ONWARD. MAIN ISSUE WILL BE HEAT LATER
PERIODS. ILL-DEFINED WARM FRONT EXPECTED TO LIFT NORTH
INTO/THROUGH STATE SUN. 850 MB TEMPS EXPECTED TO WARM SAT ONWARD
HITTING 20C EARLY IN WORK WEEK. IF MODELS SOUNDINGS
CORRECT...WOULD MIX UP TO THAT LEVEL YIELDING TEMPS AROUND 90 NEXT
MON THROUGH WED. QUESTION IS EFFECTS OF CLOUDS AND PCPN. LIKELY
TO BE ON EDGE OF CAP WITH CONVECTION NEAR OR OVER REGION. HAVE
TRENDED HIGHER POPS OVER NORTHERN WI WHERE ECMWF LINGERS FRONT.
HAVE USED BEST PERFORMING BLEND FOR TEMPS...BUMPING THEM UP A
DEGREE TO LESSEN CLIMO BIAS.
EARLY PERIODS/THU NIGHT INTO FRI NIGHT/PLEASANT WITH COOLER HIGH
PRESSURE AT THE SURFACE OVER REGION. CLEAR SKIES AND DRY
CONDITIONS TO LEAD TO COOLER NIGHTS AND MILD DAYS. HAVE SLOWED
APPROACH OF PCPN SAT GIVEN MODEL TRENDS.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 600 PM CDT WED AUG 21 2013
WL CARRY TSRA WITH GUSTY WINDS OVER ALL BUT THE RHI TAF SITES FOR
A COUPLE HRS THIS EVENING. CONDITIONS SHOULD IMPROVE QUICKLY ONCE
THE STORMS MOVE THROUGH.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE.........SKOWRONSKI
SHORT TERM.....MPC
LONG TERM......TE
AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
600 PM CDT WED AUG 21 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 323 PM CDT WED AUG 21 2013
MAIN FOCUS WILL BE ON THE FRONTAL PASSAGE TONIGHT AND THE
ASSOCIATED RAIN CHANCES.
COLD FRONT EXTENDS FROM NORTHERN WISCONSIN INTO NORTHEAST NEBRASKA
AT MID AFTERNOON. REGIONAL RADARS SHOW CONVECTIVE ACTIVITY ALONG
THE FRONT FROM NORTHERN WISCONSIN ACROSS MINNESOTA.
WATER VAPOR SATELLITE SHOWS THE MAIN SHORT WAVE TROUGH IS ALONG
THE CANADIAN BORDER MOVING INTO ONTARIO WITH A SECONDARY WAVE OVER
CENTRAL MINNESOTA. THE BEST PV ADVECTION IN THE 500-300 MB LAYER
WILL STAY TO THE NORTH OF THE AREA TONIGHT BUT THE EXPECTATION IS
THAT THE WAVE OVER MINNESOTA WILL PROVIDE JUST ENOUGH FORCING TO
HELP MAINTAIN THE CONVECTION ALONG THE FRONT AS IT COMES THROUGH.
ML CAPES AHEAD OF THE FRONT CURRENTLY ARE AROUND 3000 J/KG AND
WHILE THESE WILL DECREASE THROUGH THE EVENING WITH THE LOSS OF
HEATING...THE 21.18Z NAM INDICATES THESE WILL STAY AT OR ABOVE
1500 J/KG THROUGH THE EVENING AHEAD OF THE FRONT. THE BEST 0-6KM
SHEAR WILL REMAIN NORTH OF THE AREA CLOSER TO THE MAIN SHORT WAVE
TROUGH. HOWEVER...THE 0-3KM SHEAR WILL BE AROUND 30 KNOTS AND WILL
BE MORE THAN SUFFICIENT TO SUPPORT SOME SEVERE STORMS THROUGH THE
EVENING. LARGE HAIL AND DAMAGING WINDS STILL LOOK TO BE THE MAIN
THREATS. WILL BE INTERESTING TO SEE HOW THE CURRENT ACTIVITY
SOUTH OF THE TWIN CITIES EVOLVES THROUGH THE REMAINDER OF THE
AFTERNOON. THE 21.18Z RAP BUFKIT SOUNDINGS SUGGEST THE CAP IN
PLACE BETWEEN 750 AND 800 MB AT KRST WILL HOLD TIGHT UNTIL THE
FRONT MOVES THROUGH. IF THIS HAPPENS...THE ACTIVITY TO THE WEST
SHOULD DIMINISH AS IT MOVES IN AND THIS IS WHAT SEVERAL OF THE
SHORT RANGE MESO MODELS SUGGESTS. BASED ON THIS...HAVE TRIMMED
BACK THE RAIN CHANCES HEADING THROUGH THE EVENING ACROSS THE
WESTERN SECTIONS OF THE FORECAST AREA. FARTHER EAST...THE CAP IS
WEAKER AND IS EXPECTED TO ERODE AS THE FRONT MOVES IN...SO HAVE
MAINTAINED THE 60 TO 80 PERCENT CHANCES EAST OF THE MISSISSIPPI
RIVER.
ALL THE MODELS ALSO SUGGEST THE FRONT AND CONVECTION WILL MOVE
THROUGH PRETTY QUICK THIS EVENING TO THE POINT THAT MOST IF NOT
ALL OF THE FORECAST AREA SHOULD BE DRY BY 06Z. THUS SPED UP THE
FORECAST TO REFLECT THIS FASTER TIMING WITH JUST SOME 20 TO 40
PERCENT RAIN CHANCES ACROSS THE SOUTH FOR AFTER MIDNIGHT. HAVE
HELD ON TO SOME SMALL RAIN CHANCES ACROSS THE SOUTH FOR THURSDAY
MORNING. ALL THE MODELS INDICATE A CONVECTIVE COMPLEX WILL DEVELOP
ACROSS NEBRASKA THIS EVENING AND THEN MOVE EAST ALONG THE FRONT
TOWARD THE AREA OVERNIGHT WITH SOME SUGGESTIONS THAT THE NORTHERN
PART OF THE COMPLEX COULD SLIDE ACROSS THE SOUTHERN PARTS OF THE
AREA. OTHERWISE FOR THURSDAY...HIGH PRESSURE WILL MOVE IN FROM THE
NORTH WITH MUCH DRIER AIR SPREADING IN. NAM BUFKIT SOUNDING ACROSS
THE NORTHERN SECTIONS SHOW GOOD SUBSIDENCE OCCURRING AND WITH LOTS
OF DRY ALOFT TO MIX DOWN...DEW POINTS ARE EXPECTED TO DROP INTO
THE 40S FOR THE AFTERNOON. THIS HIGH WILL REMAIN THE DOMINANT
FEATURE FOR THE REMAINDER OF THE SHORT TERM HELPING TO KEEP
TEMPERATURES CLOSER TO NORMAL THROUGH FRIDAY WITH HIGHS IN THE
UPPER 70S TO LOWER 80S.
.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 323 PM CDT WED AUG 21 2013
CONSIDERABLE UNCERTAINTY IN THE EXTENDED IN REGARDS TO THE RAIN
CHANCES. THE UPPER LEVEL RIDGE WILL BE ANCHORED OVER THE CENTRAL
PART OF THE COUNTRY WITH ALL THE MODELS SHOWING SHORT WAVE TROUGHS
EXPECTED TO RIDE UP THE BACK SIDE AND OVER THE TOP OF THE RIDGE.
AT THE SURFACE...THE EXPECTATION IS THAT A WEAK SURFACE BOUNDARY
WILL APPROACH FROM THE WEST SATURDAY BUT STALL OUT AND BECOME
NEARLY STATIONARY BEFORE IT REACHES THE AREA. IT SHOULD THEN
WAFFLE NORTH/SOUTH AS SHORT WAVE TROUGHS MOVE AROUND THE RIDGE AND
CAUSE ROUNDS OF CONVECTION TO FORM. THE UNCERTAINTY COMES IN WHERE
THESE COMPLEXES WILL BE AND WHETHER THEY WILL IMPACT THE NORTHERN
PARTS OF THE FORECAST AREA OR NOT. AFTER THE INITIAL SHORT WAVE
TROUGH GOES BY SATURDAY WILL GENERALLY LIMIT THE RAIN CHANCES TO
THE I94 CORRIDOR FOR THE REMAINDER OF THE EXTENDED PERIOD AS THIS
AREA WILL BE CLOSEST TO THE FRONT.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 600 PM CDT WED AUG 21 2013
COLD FRONT SLIDING SOUTHEAST ACROSS THE REGION EARLY THIS
EVENING...WITH SCT/BKN SHRA/TS ALONG AND BEHIND IT. MOST OF THE
INSTABILTY WAS NORTH AND EAST OF THE TAF SITES...AND EXPECT THE
THREAT FOR STRONGER/SEVERE STORMS TO STAY AWAY FROM KRST/KLSE AS A
RESULT. THAT SAID...THE NEAR SFC LAYER IS RELATIVELY DRY AND COULD
SUPPORT ENHANCED GUSTINESS AROUND ANY THUNDERSTORM.
THE FRONT WILL LAY UP WEST TO EAST ACROSS CENTRAL IA TONIGHT. MODELS
CONTINUE TO SUGGEST THAT A THUNDERSTORM COMPLEX WILL DEVELOP OVER
NEB...TRACKING EAST ALONG AND NORTH OF THE BOUNDARY. TRACK WOULD
KEEP THE PCPN SOUTH OF KRST/KLSE...AND WILL KEEP TAFS DRY FOR NOW.
HIGH PRESSURE BUILDS IN FROM SOUTHERN CANADA THU...AND PRESSURE
GRADIENT SLACKENS. COULD SEE SOME GUSTS IN THE MORNING...BUT LOW
LEVEL WINDS WEAKEN IN THE AFTERNOON. EXPECT VFR CONDITIONS WILL SOME
SCT-BKN HIGH CLOUDS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM....04
AVIATION.....RIECK
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SHORT TERM...TONIGHT AND WEDNESDAY
ISSUED AT 230 PM CDT TUE AUG 20 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A NEARLY
STATIONARY UPPER LOW SPINNING OVER THE CENTRAL MISSISSIPPI VALLEY
AND A COLD FRONT MOVING ACROSS THE NORTHERN PLAINS. AHEAD OF THE
FRONT...SOUTHWEST WINDS ARE ADVECTION MOISTURE IN THE 900-800MB
LAYER FROM THE CENTRAL PLAINS INTO WESTERN AND CENTRAL WISCONSIN
WHERE A WIDESPREAD CU FIELD FORMED MIDDAY. AREA RADARS SHOWED A FEW CELLS
POPPED UP THIS MORNING OVER IOWA BUT HAVE SINCE FIZZLED. NO OTHER
SIGNS OF SHOWERS POPPING DESPITE INHIBITION ERODING. AS THE FRONT
MOVES INTO THE REGION TOMORROW...SEVERE WEATHER CHANCES IS THE MAIN
FORECAST CONCERN.
TONIGHT...LOW LEVEL MOISTURE AXIS WILL INITIALLY EXTEND FROM CENTRAL
IOWA TO NORTH-CENTRAL WISCONSIN AT THE START OF THE PERIOD. WITH
SCT TO BKN 5-7KFT CIGS UPSTREAM...WILL KEEP SKIES SCT FOR A GOOD
PART OF THE NIGHT. HAVE NOT SEEN MORE SPECKLES ON RADAR ASSOCIATED
WITH THIS MOISTURE TRANSPORT REGIME...SO WILL STICK WITH A DRY
FORECAST DESPITE FORECAST SOUNDINGS SHOWING 1300 J/KG OF ELEVATED
CAPE. THE MOISTURE AXIS WILL SHIFT EAST THROUGH THE NIGHT AND REACH
EAST-CENTRAL AND NORTHEAST WISCONSIN AFTER MIDNIGHT. SO SHOULD SEE
SOME CLEARING OVER WESTERN SECTIONS AND AN INCREASE OF CLOUDS OVER
EASTERN WISCONSIN LATE. A WARM SOUTHWEST BREEZE AND INCREASING
MOISTURE WILL KEEP CONDITIONS MUGGY. LOWS MAINLY IN THE 60S.
WEDNESDAY...THE DAY WILL START OUT QUIET...AS THE MOISTURE AXIS
SHIFTS SOUTHEAST OF THE REGION...WHILE THE THERMAL AXIS ARRIVES
AHEAD OF A COLD FRONT WHICH WILL MOVE INTO NORTHWEST WISCONSIN BY
18Z. TEMPS SHOULD NOT HAVE MUCH OF A PROBLEM RISING INTO THE UPPER
80S TO LOW 90S AHEAD OF THE FRONT WEDNESDAY AFTERNOON. SOME HEAT
INDICES WILL LIKELY REACH INTO THE MIDDLE 90S. BUT THE BIGGER STORY
IS SEVERE WEATHER CHANCES WEDNESDAY AFTERNOON. THE COLD FRONT WILL
PUSH INTO NORTH-CENTRAL WISCONSIN MID TO LATE AFTERNOON DURING THE
TIME OF PEAK HEATING. THOUGH HEIGHT FALLS WILL EXIST WELL BEHIND
THE FRONT...CONVERGENCE AND FGEN ALONG THE FRONT LOOK DECENT. SOME
POTENTIAL FOR DEWPOINTS TO MIX OUT INTO THE MIDDLE 60S AHEAD OF THE
FRONT BUT THAT SHOULD NOT HURT INSTABILITY TOO MUCH. MODIFYING A NAM
PROGGED SOUNDING AT 21Z NEAR RHINELANDER USING A 88/68 PARCEL YIELDS
NEARLY 3500 J/KG OF ML CAPE. IF DEWPOINTS DO MIX OUT INTO THE MID
60S...INSTABILITY WILL DROP TO 2500 J/KG. FREEZING LEVELS ARE QUITE
HIGH AT 14.5 KFT...BUT MID-LEVEL LAPSE RATES OF 6.5-7 C/KM AND
PLENTY OF CAPE SAYS THAT LARGE HAIL IS ALSO A THREAT IN ADDITION TO
DAMAGING WINDS. 0-6KM BULK SHEAR IS 25-30 KTS WHICH SUGGESTS
MULTI-CELLS TO SOME SMALL BOWS ARE POSSIBLE. TIMING WISE...LOOKING
AT A MID AFTERNOON FOR N-C WISCONSIN...AND LATE AFTERNOON TO EARLY
EVENING OVER CENTRAL AND FAR NORTHEAST WISCONSIN.
.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY
ISSUED AT 230 PM CDT TUE AUG 20 2013
LITTLE CHANGE WITH THE GOING FORECAST FOR WEDNESDAY NIGHT WITH
RESPECT TO THE POTENTIAL OF STRONG TO SEVERE STORMS. PLENTY OF
INSTABILITY WITH CAPES BETWEEN 2000 TO 3000 J/KG AVAILABLE ALONG
AND AHEAD OF A COLD FRONT DROPPING OVER THE GREAT LAKES REGION.
SHORT WAVE TROUGH DIVING INTO THE NORTHERN GREAT LAKES REGION WITH
A RRQ REGION OF A JET WILL BE ASSOCIATED WITH THE FRONTAL PASSAGE.
INCREASING W/NW MID LEVEL WINDS LATER AFTERNOON AND EVENING WILL
PROVIDE SOME DEEPER SHEAR WITH THE FRONT. DAMAGING WINDS AND HAIL
THE PRIMARY THREATS. PWATS NEAR 1.85 INCHES AHEAD AND ALONG THE
FRONT AND HEAVY RAIN FALL POSSIBLE AFTERNOON AND EVENING NEAR THE
RRQ REGION OF THE JET ACROSS THE NORTH IF STORMS TRAIN FOR A
PERIOD OF TIME.
HIGH PRESSURE DRIFTING OVER THE STATE THURSDAY INTO FRIDAY WILL
PROVIDE QUIET CONDITIONS ALONG WITH NEAR NORMAL TEMPERATURES AND A
DRIER AIR MASS.
WARM AND MORE HUMID AIR TO RETURN AGAIN THIS WEEKEND AND INTO
EARLY NEXT WEEK...AS THE UPPER RIDGE BUILDS INTO THE NORTHERN
PLAINS AND GREAT LAKES REGION. MDM RANGE MODELS IN GENERAL WERE
MAINLY FOCUSING PERIODS OF CONVECTION ON THE PERIMETER OF THE
RIDGE WITH PWATS INCREASING TO 1.50 TO 2.00 OVER THE NORTHERN
GREAT LAKES REGION. WITH THE RETURN OF AN UNSTABLE AIR MASS ALONG
WITH A CAP EDGE LOOMING NEAR OR OVER NORTHERN WISCONSIN...POTENTIAL
OF AT LEAST STRONG STORMS FOR LATER INTO THE WEEKEND AND INTO NEXT
WEEK FOR PART OF THE FORECAST AREA.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1208 PM CDT TUE AUG 20 2013
SCATTERED TO BROKEN CUMULUS CLOUDS WITH BASES BETWEEN
5000 AND 7000 FEET WILL MOVE ACROSS CENTRAL AND NORTH-CENTRAL
WISCONSIN THIS AFTERNOON AND INTO EAST-CENTRAL AND NORTHEAST
WISCONSIN TONIGHT. MOSTLY VFR TONIGHT THOUGH OUTSIDE OF ANY GROUND
FOG OR HAZE THAT FORMS TOWARD DAWN. A COLD FRONT WILL PRODUCE A LINE
OF STRONG SHOWERS AND THUNDERSTORMS WEDNESDAY AFTERNOON AND EVENING
AS IT MOVES ACROSS THE REGION.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......MPC
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1211 PM CDT TUE AUG 20 2013
.UPDATE...
HIGH TEMPERATURES COULD BE A DEGREE OR TWO WARMER. ECMWF 925 MB
TEMPS AROUND 23 C WOULD SUPPORT A HIGH OF 85...BUT RAP AND NAM
SHOWING WE COULD BE A BIT WARMER. TEMPERATURES ACROSS THE AREA ARE
ALREADY IN THE LOWER 80S FOR THE MOST PART. ALSO...WE/VE ALREADY
SEEN A GOOD DEAL OF SUNSHINE AND WITH A GENERAL LACK OF MOISTURE WE
MIGHT SEE A BIT MORE SUNSHINE THEN EXPECTED...EVEN WITH SOME CAPE.
&&
.AVIATION/18Z TAFS/...
VFR CONDITIONS WILL CONTINUE THROUGHOUT THE DAY...WITH FEW OR SCT
PATCHY CUMULUS CLOUDS DEVELOPING. ADDITIONAL MOISTURE MOVING IN
FROM THE WEST LATER TONIGHT INTO TOMORROW MORNING COULD BRING A
MORE SOLID CLOUD DECK...BUT IT WOULD STILL BE ABOVE 3000 FT.
SOUTH OR SOUTHWEST WINDS WILL CONTINUE THROUGHOUT THE PERIOD.
PRECIP CHANCES LOOK LIKE THEY WILL HOLD OFF UNTIL AFTER 21Z
WEDNESDAY AT MSN AND 00Z THURSDAY AT MKE.
&&
.PREV DISCUSSION... /ISSUED 347 AM CDT TUE AUG 20 2013/
TODAY AND TONIGHT...FORECAST CONFIDENCE...HIGH
PATCHY FOG WITH SOME DENSE GROUND FOG IN THE RIVER VALLEYS AND USUAL
LOW AREAS EARLY THIS MORNING.
WEAK MID/UPPER LEVEL LOW WILL REMAIN NEARLY STATIONARY OVER ILLINOIS
TODAY BEFORE HEADING TO SOUTHERN INDIANA TONIGHT. MAIN MID/UPPER
JET EXTENDS ACROSS FAR SOUTHERN CANADA.
SOME MOISTURE SEEN ON THE NAM FORECAST SOUNDINGS AROUND 6 THSD FT
WITH A CAP AROUND 7 THSD FT. MID LEVELS REMAIN DRY AND WITH LITTLE
OR NO UPWARD MOTION THE 800 J/KG CAPE WILL LIKELY NOT BE ABLE TO
SUPPORT DEEP MOIST CONVECTION. THE NAM INCREASES THE 850 MB
MOISTURE TONIGHT ESPECIALLY OVER SOUTH CENTRAL WISCONSIN AND
WEAKENS/ELIMINATES THE CAP. THE SOUNDINGS HAVE AROUND 1600 J/KG OF
ELEVATED CAPE LIFTED FROM 5 THSD FT BUT AGAIN NO LIFTING MECHANISM.
WARMER AIRMASS STEADILY MOVING INTO THE REGION PER 925/850 MB
TEMPERATURE TRENDS. HOWEVER THE MAIN THERMAL RIDGE REMAINS TO THE
NORTHWEST.
SURFACE HIGH PRESSURE CENTERED OVER THE MID ATLANTIC STATES WITH A
WEAK SOUTH/SOUTHWEST LOW LEVEL FLOW. THEREFORE QUIET WEATHER IS
EXPECTED TO CONTINUE...WITH CONTINUED WARMING TEMPERATURES.
WEDNESDAY AND THURSDAY...FORECAST CONFIDENCE...MEDIUM
A COLD FRONT WILL APPROACH ON WEDNESDAY...WITH CURRENT MODEL
TIMING SUGGESTING MAINLY DRY WEATHER INTO THE AFTERNOON. GIVEN
THIS...KEPT WARM TEMPS AROUND 90 WITH SOUTHWEST WINDS AND SOME
SUNSHINE EXPECTED.
SOME TIMING DIFFERENCES WITH THE FRONT AND PRECIP CHANCES LATE
AFTERNOON INTO THE NIGHT. THE 00Z GFS AND NAM WERE A BIT QUICKER
THAN THE ECMWF AND CANADIAN...WITH STORMS IN THE NORTH BY EVENING.
INCREASED POPS A BIT LATE AFTERNOON...WITH SHOWERS THEN LIKELY
EVENING AND OVERNIGHT AS THE FRONT MOVES THROUGH. STORMS COULD
APPROACH OR REACH SEVERE LIMITS...LIKELY DEPENDING ON THE TIMING
OF THE FRONT AND REMAINING INSTABILITY. SPC DAY 2 CONVECTIVE
OUTLOOKS HIGHLIGHTS MOST OF THE CWA IN A SLIGHT RISK FOR SEVERE
STORMS.
COULD SEE A FEW LINGERING SHOWERS OR STORMS THURSDAY...MAINLY
DURING THE MORNING HOURS. WENT WITH A CONSENSUS OF MODEL HIGH
TEMPS FOR THURSDAY...AS MODELS NOT IN GREAT AGREEMENT WITH THE
EXTENT OF POST-FRONTAL COOLING.
FRIDAY THROUGH MONDAY...FORECAST CONFIDENCE...MEDIUM
HIGH PRESSURE IS EXPECTED TO BRING PLEASANT WEATHER FRIDAY...WITH
MOSTLY SUNNY SKIES AND NEAR NORMAL TEMPERATURES LIKELY.
MODELS DEPICT A WEAK SHORTWAVE SATURDAY...BUT NOT LOOKING
SUBSTANTIAL ENOUGH FOR POPS AT THIS TIME. DRY WEATHER WILL LIKELY
CONTINUE SUNDAY WITH GFS AND ECMWF SHOWING THE AXIS OF THE UPPER
RIDGE MOVING OVERHEAD. WILL PROBABLY SEE TEMPS CLIMB BACK ABOVE
NORMAL UNDER THE RIDGE.
THE LATEST ECMWF SHOWS A FRONT DROPPING THROUGH MONDAY...THOUGH
THE GFS MAINTAINS THE RIDGE AND WARM TEMPS SIMILAR TO THE
PREVIOUS ECMWF. KEPT THINGS MAINLY DRY FOR NOW...WITH ABOVE NORMAL
TEMPS CONTINUING.
AVIATION/12Z TAFS/...
PATCHY IFR/LIFR MAINLY IN RIVER VALLEYS AND LOW AREAS. AREAS OF MVFR
HAZE/FOG TIL AN HOUR OR TWO AFTER SUNRISE. THEN VFR CONDITIONS
EXPECTED TODAY AND THIS EVENING.
SCATTERED FAIR WEATHER DIURNAL CUMULUS EXPECTED LATE THIS MORNING
AND AFTERNOON.
SURFACE HIGH PRESSURE CENTERED OVER THE MID ATLANTIC STATES WITH A
WEAK SOUTH/SOUTHWEST LOW LEVEL FLOW.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...MEB
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
WEDNESDAY THROUGH MONDAY...DDV
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1201 PM CDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 351 AM CDT TUE AUG 20 2013
MAIN FORECAST CONCERNS ARE ON THUNDERSTORM CHANCES WEDNESDAY INTO
THURSDAY AND HIGH TEMPERATURES LATE IN THE WEEKEND INTO EARLY NEXT
WEEK.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED A
SHORTWAVE TROUGH OVER SOUTHERN WISCONSIN AND NORTHERN
ILLINOIS...DRIFTING SOUTH. RIDGING WAS MOVING INTO THE UPPER
MISSISSIPPI RIVER VALLEY PROVIDING MOSTLY CLEAR TO PARTLY CLOUDY
SKIES AND QUIET CONDITIONS OVER THE AREA. SURFACE OBSERVATIONS
SHOWED A COLD FRONT EXTENDING FROM SOUTHERN MANITOBA THROUGH
WESTERN NORTH DAKOTA INTO EASTERN WYOMING WITH A BROAD HIGH
CENTERED OVER THE OHIO RIVER VALLEY. THE FORECAST AREA IS LOCATED
BETWEEN THESE TWO FEATURES WITH WARM SOUTHERLY FLOW ACROSS THE
REGION.
THE SHORTWAVE TROUGH WILL CLOSE INTO A WEAK UPPER LOW OVER ILLINOIS
TODAY. MEANWHILE...THE COLD FRONT WILL DRIFT SOUTHEAST AND BY LATE
THIS AFTERNOON IS EXPECTED TO STRETCH FROM NORTHWEST MINNESOTA
THROUGH EASTERN NORTH DAKOTA INTO CENTRAL SOUTH DAKOTA. THE UPPER
LEVEL RIDGING SHOULD WIN OUT TODAY PROVIDING PARTLY TO MOSTLY
SUNNY SKIES. INTERESTING TO NOTE THAT AFTERNOON MLCAPE VALUES
CLIMB TO 2500 TO 3500 J/KG THIS AFTERNOON ACROSS MUCH OF THE
FORECAST AREA. WITHOUT ANY REAL TRIGGER TO GET CONVECTION TO FIRE
THINKING THE AREA SHOULD REMAIN DRY THROUGH THE DAY. WILL HAVE TO
KEEP A CLOSE EYE ON THE POTENTIAL FOR AN ISOLATED SHOWER OR STORM
UNDER PEAK HEATING LATE THIS AFTERNOON. PLAN ON HIGH TEMPERATURES
CLIMBING INTO THE UPPER 80S TO AROUND 90. THE COLD FRONT WILL
CONTINUE ITS SOUTHEAST MOVEMENT TONIGHT INTO WEDNESDAY MORNING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 351 AM CDT TUE AUG 20 2013
THE COLD FRONT WILL BE POSITIONED FROM FAR NORTHWEST WISCONSIN INTO
EXTREME NORTHWEST IOWA EARLY WEDNESDAY MORNING. FORECAST MODELS ARE
SHOWING SOME DIFFERENCES ON WHEN THE FRONT WILL MOVE INTO THE
FORECAST AREA. THE NAM OFFERS THE FASTEST SOLUTION BRINGING THE
FRONT INTO THE FORECAST AREA LATE WEDNESDAY MORNING...SHIFTING
SOUTH OF THE INTERSTATE 90 CORRIDOR WEDNESDAY EVENING AND STALLING
OVER NORTHERN IOWA/ILLINOIS. THE ECMWF HAS THE SLOWEST SOLUTION
AND DOESN/T BRING THE FRONT INTO THE FORECAST AREA UNTIL WEDNESDAY
EVENING. THE ECMWF SOLUTION SUGGESTS THAT A SHORTWAVE WILL TRIGGER
SHOWERS AND STORMS OVER NORTHWEST WISCONSIN WEDNESDAY
AFTERNOON...SPREADING SOUTHEAST DURING THE LATE AFTERNOON AND
EVENING HOURS. SHOWERS AND STORMS THEN FIRE ALONG THE FRONT
THROUGH THE OVERNIGHT HOURS WITH THE FRONT FINALLY PUSHING SOUTH
OF THE AREA BY EARLY THURSDAY AFTERNOON. THERE REMAINS TIMING
ISSUES TO WORK OUT...BUT THINKING THERE REMAINS A CHANCE OF SEEING
SEVERE THUNDERSTORMS ON WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT.
0-6KM BULK SHEAR IS THE MOST FAVORABLE FOR SEVERE STORMS OVER
NORTH CENTRAL WISCONSIN...WHERE VALUES RANGE FROM 30 TO 40 KTS.
PLENTY OF INSTABILITY TO WORK WITH AHEAD OF THE FRONT WITH MLCAPE
VALUES CLIMBING TO AROUND 2000 J/KG. THE MAIN THREATS FROM THE
STORMS WILL BE LARGE HAIL AND DAMAGING WINDS. SHEAR IS VERY
MARGINAL AT BEST OVER SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND
SOUTHWEST WISCONSIN...BUT THINKING THE STRONG INSTABILITY WILL BE
ENOUGH TO OVERCOME THE LACK OF STRONG SHEAR. THE FRONT FINALLY
SHIFTS SOUTH OF THE AREA LATE ON THURSDAY AS HIGH PRESSURE BUILDS
IN. THE FRONT ATTEMPTS TO LIFT NORTH AS A WARM FRONT ON FRIDAY
GENERATING SOME SHOWERS AND STORMS ALONG IT. LATEST GUIDANCE
SUGGESTS THAT THE FRONT WASHES OUT AS A SURFACE HIGH HOLDS STRONG
OVER THE WESTERN GREAT LAKES. UPPER RIDGE THEN BUILDS OVER THE
REGION SATURDAY INTO SUNDAY WITH WARMING TEMPERATURES EXPECTED.
WILL HAVE TO KEEP A CLOSE EYE ON SHORTWAVES ROTATING THROUGH THE
NORTHERN PERIPHERY OF THE RIDGE OVER NORTHERN WISCONSIN WHERE
SHOWERS STORMS WILL BE POSSIBLE. 850 MB STANDARDIZED ANOMALIES
CLIMB TO PLUS 2 ON SUNDAY...SUGGESTING THE POTENTIAL FOR NEAR
RECORD HIGH TEMPERATURES. 925 MB TEMPERATURES WARM TO 28 C ON
SUNDAY BEFORE ANOTHER COLD FRONT SLIPS SOUTH THROUGH THE REGION ON
MONDAY. HIGHS ON SUNDAY AND MONDAY SHOULD CLIMB INTO THE UPPER 80S
TO LOWER 90S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1201 PM CDT TUE AUG 20 2013
SOME MID LEVEL CLOUDS EXPECTED TO REMAIN OVER THE AREA INTO THE
EARLY EVENING IN A BROAD AREA OF LOW LEVEL WARM AIR ADVECTION.
WOULD NOT BE SURPRISED IF A SHOWER OR TWO POPPED UP IN THIS WARM
AIR ADVECTION...BUT IF THEY DO...WOULD THINK THEY WOULD BE TOO
ISOLATED TO MAKE IT WORTH EVEN INCLUDING A VCSH AT THIS POINT. VFR
CONDITIONS EXPECTED FOR THE REMAINDER OF THE PERIOD AS A COLD
FRONT SLOWLY APPROACHES FROM THE NORTHWEST. WARM AIR SPREADING IN
AHEAD OF THE COLD FRONT WILL CAP OFF THE LOW LEVELS SO ONLY SOME
HIGH LEVEL CLOUDS EXPECTED TO START SPILLING IN WEDNESDAY MORNING.
THE GRADIENT WILL START TO TIGHTEN WEDNESDAY MORNING TO PUSH
SUSTAINED SPEEDS OVER 10 KNOTS BUT THE LOW LEVEL INVERSION WILL
NOT MIX OUT UNTIL AFTERNOON WHEN IT SHOULD GET GUSTY AS WELL.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
626 AM CDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 351 AM CDT TUE AUG 20 2013
MAIN FORECAST CONCERNS ARE ON THUNDERSTORM CHANCES WEDNESDAY INTO
THURSDAY AND HIGH TEMPERATURES LATE IN THE WEEKEND INTO EARLY NEXT
WEEK.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED A
SHORTWAVE TROUGH OVER SOUTHERN WISCONSIN AND NORTHERN
ILLINOIS...DRIFTING SOUTH. RIDGING WAS MOVING INTO THE UPPER
MISSISSIPPI RIVER VALLEY PROVIDING MOSTLY CLEAR TO PARTLY CLOUDY
SKIES AND QUIET CONDITIONS OVER THE AREA. SURFACE OBSERVATIONS
SHOWED A COLD FRONT EXTENDING FROM SOUTHERN MANITOBA THROUGH
WESTERN NORTH DAKOTA INTO EASTERN WYOMING WITH A BROAD HIGH
CENTERED OVER THE OHIO RIVER VALLEY. THE FORECAST AREA IS LOCATED
BETWEEN THESE TWO FEATURES WITH WARM SOUTHERLY FLOW ACROSS THE
REGION.
THE SHORTWAVE TROUGH WILL CLOSE INTO A WEAK UPPER LOW OVER ILLINOIS
TODAY. MEANWHILE...THE COLD FRONT WILL DRIFT SOUTHEAST AND BY LATE
THIS AFTERNOON IS EXPECTED TO STRETCH FROM NORTHWEST MINNESOTA
THROUGH EASTERN NORTH DAKOTA INTO CENTRAL SOUTH DAKOTA. THE UPPER
LEVEL RIDGING SHOULD WIN OUT TODAY PROVIDING PARTLY TO MOSTLY
SUNNY SKIES. INTERESTING TO NOTE THAT AFTERNOON MLCAPE VALUES
CLIMB TO 2500 TO 3500 J/KG THIS AFTERNOON ACROSS MUCH OF THE
FORECAST AREA. WITHOUT ANY REAL TRIGGER TO GET CONVECTION TO FIRE
THINKING THE AREA SHOULD REMAIN DRY THROUGH THE DAY. WILL HAVE TO
KEEP A CLOSE EYE ON THE POTENTIAL FOR AN ISOLATED SHOWER OR STORM
UNDER PEAK HEATING LATE THIS AFTERNOON. PLAN ON HIGH TEMPERATURES
CLIMBING INTO THE UPPER 80S TO AROUND 90. THE COLD FRONT WILL
CONTINUE ITS SOUTHEAST MOVEMENT TONIGHT INTO WEDNESDAY MORNING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 351 AM CDT TUE AUG 20 2013
THE COLD FRONT WILL BE POSITIONED FROM FAR NORTHWEST WISCONSIN INTO
EXTREME NORTHWEST IOWA EARLY WEDNESDAY MORNING. FORECAST MODELS ARE
SHOWING SOME DIFFERENCES ON WHEN THE FRONT WILL MOVE INTO THE
FORECAST AREA. THE NAM OFFERS THE FASTEST SOLUTION BRINGING THE
FRONT INTO THE FORECAST AREA LATE WEDNESDAY MORNING...SHIFTING
SOUTH OF THE INTERSTATE 90 CORRIDOR WEDNESDAY EVENING AND STALLING
OVER NORTHERN IOWA/ILLINOIS. THE ECMWF HAS THE SLOWEST SOLUTION
AND DOESN/T BRING THE FRONT INTO THE FORECAST AREA UNTIL WEDNESDAY
EVENING. THE ECMWF SOLUTION SUGGESTS THAT A SHORTWAVE WILL TRIGGER
SHOWERS AND STORMS OVER NORTHWEST WISCONSIN WEDNESDAY
AFTERNOON...SPREADING SOUTHEAST DURING THE LATE AFTERNOON AND
EVENING HOURS. SHOWERS AND STORMS THEN FIRE ALONG THE FRONT
THROUGH THE OVERNIGHT HOURS WITH THE FRONT FINALLY PUSHING SOUTH
OF THE AREA BY EARLY THURSDAY AFTERNOON. THERE REMAINS TIMING
ISSUES TO WORK OUT...BUT THINKING THERE REMAINS A CHANCE OF SEEING
SEVERE THUNDERSTORMS ON WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT.
0-6KM BULK SHEAR IS THE MOST FAVORABLE FOR SEVERE STORMS OVER
NORTH CENTRAL WISCONSIN...WHERE VALUES RANGE FROM 30 TO 40 KTS.
PLENTY OF INSTABILITY TO WORK WITH AHEAD OF THE FRONT WITH MLCAPE
VALUES CLIMBING TO AROUND 2000 J/KG. THE MAIN THREATS FROM THE
STORMS WILL BE LARGE HAIL AND DAMAGING WINDS. SHEAR IS VERY
MARGINAL AT BEST OVER SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND
SOUTHWEST WISCONSIN...BUT THINKING THE STRONG INSTABILITY WILL BE
ENOUGH TO OVERCOME THE LACK OF STRONG SHEAR. THE FRONT FINALLY
SHIFTS SOUTH OF THE AREA LATE ON THURSDAY AS HIGH PRESSURE BUILDS
IN. THE FRONT ATTEMPTS TO LIFT NORTH AS A WARM FRONT ON FRIDAY
GENERATING SOME SHOWERS AND STORMS ALONG IT. LATEST GUIDANCE
SUGGESTS THAT THE FRONT WASHES OUT AS A SURFACE HIGH HOLDS STRONG
OVER THE WESTERN GREAT LAKES. UPPER RIDGE THEN BUILDS OVER THE
REGION SATURDAY INTO SUNDAY WITH WARMING TEMPERATURES EXPECTED.
WILL HAVE TO KEEP A CLOSE EYE ON SHORTWAVES ROTATING THROUGH THE
NORTHERN PERIPHERY OF THE RIDGE OVER NORTHERN WISCONSIN WHERE
SHOWERS STORMS WILL BE POSSIBLE. 850 MB STANDARDIZED ANOMALIES
CLIMB TO PLUS 2 ON SUNDAY...SUGGESTING THE POTENTIAL FOR NEAR
RECORD HIGH TEMPERATURES. 925 MB TEMPERATURES WARM TO 28 C ON
SUNDAY BEFORE ANOTHER COLD FRONT SLIPS SOUTH THROUGH THE REGION ON
MONDAY. HIGHS ON SUNDAY AND MONDAY SHOULD CLIMB INTO THE UPPER 80S
TO LOWER 90S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 626 AM CDT TUE AUG 20 2013
VFR CONDITIONS ARE EXPECTED THROUGH TOMORROW MORNING WITH SOME
5-8KFT ALTOCUMULUS TO CONTEND WITH TODAY. A PASSING MID LEVEL
TROUGH IS AIDING IN THE DEVELOPMENT OF THIS BKN TO OVC MID LEVEL
DECK THAT EXTENDS FROM NORTHERN WISCONSIN DOWN THROUGH IOWA. WINDS
WILL BE ON THE INCREASE OUT OF THE SOUTH-SOUTHWEST TODAY AS THE
PRESSURE GRADIENT CONTINUES TO TIGHTEN UP ACROSS THE REGION.
EXPECT GUSTS OF 16-20KTS LATER THIS MORNING ON INTO THE AFTERNOON.
SKIES WILL CLEAR BY TONIGHT AS DRIER UPPER LEVEL AIR MOVES IN
FROM THE NORTH.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
351 AM CDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 351 AM CDT TUE AUG 20 2013
MAIN FORECAST CONCERNS ARE ON THUNDERSTORM CHANCES WEDNESDAY INTO
THURSDAY AND HIGH TEMPERATURES LATE IN THE WEEKEND INTO EARLY NEXT
WEEK.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED A
SHORTWAVE TROUGH OVER SOUTHERN WISCONSIN AND NORTHERN
ILLINOIS...DRIFTING SOUTH. RIDGING WAS MOVING INTO THE UPPER
MISSISSIPPI RIVER VALLEY PROVIDING MOSTLY CLEAR TO PARTLY CLOUDY
SKIES AND QUIET CONDITIONS OVER THE AREA. SURFACE OBSERVATIONS
SHOWED A COLD FRONT EXTENDING FROM SOUTHERN MANITOBA THROUGH
WESTERN NORTH DAKOTA INTO EASTERN WYOMING WITH A BROAD HIGH
CENTERED OVER THE OHIO RIVER VALLEY. THE FORECAST AREA IS LOCATED
BETWEEN THESE TWO FEATURES WITH WARM SOUTHERLY FLOW ACROSS THE
REGION.
THE SHORTWAVE TROUGH WILL CLOSE INTO A WEAK UPPER LOW OVER ILLINOIS
TODAY. MEANWHILE...THE COLD FRONT WILL DRIFT SOUTHEAST AND BY LATE
THIS AFTERNOON IS EXPECTED TO STRETCH FROM NORTHWEST MINNESOTA
THROUGH EASTERN NORTH DAKOTA INTO CENTRAL SOUTH DAKOTA. THE UPPER
LEVEL RIDGING SHOULD WIN OUT TODAY PROVIDING PARTLY TO MOSTLY
SUNNY SKIES. INTERESTING TO NOTE THAT AFTERNOON MLCAPE VALUES
CLIMB TO 2500 TO 3500 J/KG THIS AFTERNOON ACROSS MUCH OF THE
FORECAST AREA. WITHOUT ANY REAL TRIGGER TO GET CONVECTION TO FIRE
THINKING THE AREA SHOULD REMAIN DRY THROUGH THE DAY. WILL HAVE TO
KEEP A CLOSE EYE ON THE POTENTIAL FOR AN ISOLATED SHOWER OR STORM
UNDER PEAK HEATING LATE THIS AFTERNOON. PLAN ON HIGH TEMPERATURES
CLIMBING INTO THE UPPER 80S TO AROUND 90. THE COLD FRONT WILL
CONTINUE ITS SOUTHEAST MOVEMENT TONIGHT INTO WEDNESDAY MORNING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 351 AM CDT TUE AUG 20 2013
THE COLD FRONT WILL BE POSITIONED FROM FAR NORTHWEST WISCONSIN INTO
EXTREME NORTHWEST IOWA EARLY WEDNESDAY MORNING. FORECAST MODELS ARE
SHOWING SOME DIFFERENCES ON WHEN THE FRONT WILL MOVE INTO THE
FORECAST AREA. THE NAM OFFERS THE FASTEST SOLUTION BRINGING THE
FRONT INTO THE FORECAST AREA LATE WEDNESDAY MORNING...SHIFTING
SOUTH OF THE INTERSTATE 90 CORRIDOR WEDNESDAY EVENING AND STALLING
OVER NORTHERN IOWA/ILLINOIS. THE ECMWF HAS THE SLOWEST SOLUTION
AND DOESN/T BRING THE FRONT INTO THE FORECAST AREA UNTIL WEDNESDAY
EVENING. THE ECMWF SOLUTION SUGGESTS THAT A SHORTWAVE WILL TRIGGER
SHOWERS AND STORMS OVER NORTHWEST WISCONSIN WEDNESDAY
AFTERNOON...SPREADING SOUTHEAST DURING THE LATE AFTERNOON AND
EVENING HOURS. SHOWERS AND STORMS THEN FIRE ALONG THE FRONT
THROUGH THE OVERNIGHT HOURS WITH THE FRONT FINALLY PUSHING SOUTH
OF THE AREA BY EARLY THURSDAY AFTERNOON. THERE REMAINS TIMING
ISSUES TO WORK OUT...BUT THINKING THERE REMAINS A CHANCE OF SEEING
SEVERE THUNDERSTORMS ON WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT.
0-6KM BULK SHEAR IS THE MOST FAVORABLE FOR SEVERE STORMS OVER
NORTH CENTRAL WISCONSIN...WHERE VALUES RANGE FROM 30 TO 40 KTS.
PLENTY OF INSTABILITY TO WORK WITH AHEAD OF THE FRONT WITH MLCAPE
VALUES CLIMBING TO AROUND 2000 J/KG. THE MAIN THREATS FROM THE
STORMS WILL BE LARGE HAIL AND DAMAGING WINDS. SHEAR IS VERY
MARGINAL AT BEST OVER SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND
SOUTHWEST WISCONSIN...BUT THINKING THE STRONG INSTABILITY WILL BE
ENOUGH TO OVERCOME THE LACK OF STRONG SHEAR. THE FRONT FINALLY
SHIFTS SOUTH OF THE AREA LATE ON THURSDAY AS HIGH PRESSURE BUILDS
IN. THE FRONT ATTEMPTS TO LIFT NORTH AS A WARM FRONT ON FRIDAY
GENERATING SOME SHOWERS AND STORMS ALONG IT. LATEST GUIDANCE
SUGGESTS THAT THE FRONT WASHES OUT AS A SURFACE HIGH HOLDS STRONG
OVER THE WESTERN GREAT LAKES. UPPER RIDGE THEN BUILDS OVER THE
REGION SATURDAY INTO SUNDAY WITH WARMING TEMPERATURES EXPECTED.
WILL HAVE TO KEEP A CLOSE EYE ON SHORTWAVES ROTATING THROUGH THE
NORTHERN PERIPHERY OF THE RIDGE OVER NORTHERN WISCONSIN WHERE
SHOWERS STORMS WILL BE POSSIBLE. 850 MB STANDARDIZED ANOMALIES
CLIMB TO PLUS 2 ON SUNDAY...SUGGESTING THE POTENTIAL FOR NEAR
RECORD HIGH TEMPERATURES. 925 MB TEMPERATURES WARM TO 28 C ON
SUNDAY BEFORE ANOTHER COLD FRONT SLIPS SOUTH THROUGH THE REGION ON
MONDAY. HIGHS ON SUNDAY AND MONDAY SHOULD CLIMB INTO THE UPPER 80S
TO LOWER 90S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1148 PM CDT MON AUG 19 2013
TRANQUIL...ZONAL FLOW WILL KEEP THINGS RELATIVELY QUIET A COUPLE
MORE DAYS. PASSING...WEAK SHORT WAVE TROUGH HAS LEFT SOME RESIDUAL
MOISTURE IN LOW TO MID LEVELS CREATING SHORT LIVED VFR CEILINGS THIS
EVENING BUT THOSE SHOULD DISSIPATE OVERNIGHT.
SMOKE IN AIRMASS SWEEPING IN FROM WESTERN FOREST FIRES COULD DROP
VISIBILITIES INTO 5-6SM AT TIMES EARLY TUESDAY...OTHERWISE VFR. MORE
DIURNAL CUMULUS POSSIBLE AS WELL WITH STEADY SOUTH TO SOUTHWEST LOW
LEVEL FLOW INTO MID WEEK.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...SHEA
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1148 PM CDT MON AUG 19 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 249 PM CDT MON AUG 19 2013
MAIN FORECAST CONCERNS ARE ON ANY POTENTIAL PRECIPITATION TONIGHT
AND THEN TEMPERATURES FOR TUESDAY.
CURRENTLY AS OF 19Z...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING
ALONG THE WEST COAST OF BRITISH COLUMBIA...UPPER RIDGING FROM THE
SOUTHWESTERN U.S. INTO THE DAKOTAS...AND A SHORTWAVE TROUGH OVER
CENTRAL MN. THE MAIN IMPACT TO THE FORECAST AREA WITH THE SHORTWAVE
TROUGH HAS BEEN TO SPREAD SOME MID AND HIGH CLOUDS ACROSS. DRY AIR
IN THE MID LEVELS OF THE ATMOSPHERE SEEN ON THE 12Z MPX SOUNDING...
AS WELL AS A CAPPING INVERSION AT 750MB ON THAT SOUNDING...HAS
PREVENTED THE SHORTWAVE FROM PRODUCING PRECIPITATION IN THE FORECAST
AREA. THE CLOUD COVER HAS ALSO HELD BACK TEMPERATURES FROM REACHING
THEIR MAXIMUM POTENTIAL. 16C 850MB TEMP ON THE MPX SOUNDING WAS
ADVECTING EAST INTO THE FORECAST AREA...WHICH NORMALLY WOULD SUPPORT
MID TO EVEN UPPER 80S WITH CLEAR SKIES. HOWEVER...THE CLOUDS HAVE
HELD TEMPS DOWN INTO THE UPPER 70S TO LOW 80S THUS FAR. LOW LEVEL
SOUTHERLY FLOW HAS SLOWLY BEEN BRINGING IN MORE MOISTURE WITH
DEWPOINTS IN THE UPPER 50S TO LOW 60S. TO THE NORTHWEST...A COLD
FRONT STRETCHED FROM CENTRAL MANITOBA INTO WESTERN MONTANA. AHEAD OF
THE FRONT...12Z RAOBS SHOWED EVEN WARMER AIR ACROSS THE NORTHERN
PLAINS...WITH 850MB READINGS OF 20-25C AT BIS...ABR...UNR AND GGW.
700MB TEMPS WERE WARMING AS WELL...BETWEEN 8-13C.
SYNOPTIC OVERVIEW...
THE SHORTWAVE TROUGH OVER CENTRAL MN IS PROGGED TO DROP SOUTH
THROUGH THE FORECAST AREA THIS EVENING...WITH THE EXTENSION OF THE
UPPER RIDGE OVER THE DAKOTAS FOLLOWING IN BEHIND IT FOR THE
OVERNIGHT HOURS INTO TUESDAY.
DETAILS...
GIVEN THE DRY AIRMASS IN PLACE SUB THE MID-CLOUD LAYER AS WELL AS
THE CAPPING...NOT ANTICIPATING ANY PRECIPITATION TO ACCOMPANY THE
SHORTWAVE AS IT DROPS THROUGH THE FORECAST AREA THIS EVENING. WE
SHOULD SEE SOME CLEARING AS WELL...BOTH OF THE MID/HIGH CLOUDS AND
DIURNAL CUMULUS...AS SUBSIDENCE WORKS IN BEHIND THE SHORTWAVE
TROUGH. 850MB MOISTURE TRANSPORT THEN KICKS IN...TRANSPORTING MORE
LOW LEVEL MOISTURE INTO THE AREA. THE 19.12Z NAM/REGIONAL CANADIAN
BOTH DEVELOP A FEW ACCAS TYPE SHOWERS AND THUNDERSTORMS ON THE EDGE
OF THIS MOISTURE TRANSPORT FROM SOUTHEAST MN INTO NORTHWEST WI.
THESE ARE REALLY THE ONLY MODELS SHOWING THIS...AND WITH A BROAD
850MB MOISTURE TRANSPORT PLUME PROGGED COMBINED WITH SUBSIDENCE...
THINK THEY ARE OVERDONE AND KEPT A DRY FORECAST GOING. WORTH KEEPING
AN EYE ON...THOUGH.
THE MORE MOISTURE COMING IN COMBINED WITH DAYTIME HEATING SHOULD
YIELD TO PLENTY OF CUMULUS ON TUESDAY. LITTLE IN THE WAY OF CAPPING
IS PROGGED TOMORROW WITH MLCIN VALUES DROPPING TO 30-40 J/KG IN THE
AFTERNOON...WHILE MLCAPES GROW TO 1500-2500 J/KG. HOWEVER...THERE IS
NO TRIGGER PRESENT TO ALLOW THE RELEASE OF THE INSTABILITY.
THEREFORE...DRY CONDITIONS ARE FORECAST THROUGH TUESDAY.
TEMPERATURES TONIGHT EXPECTED TO BE WARMER...ESPECIALLY OVER THE
NORTHWEST HALF OF THE FORECAST AREA...DUE TO A SOUTHERLY BREEZE AND
HIGHER DEWPOINTS. THE SOUTHERLY BREEZE SHOULD PRECLUDE VALLEY
FOG PRETTY MUCH EVERYWHERE EXCEPT FOR THE WISCONSIN RIVER VALLEY.
850MB AND 925MB TEMPS ARE PROGGED ABOUT 2-3C HIGHER ON TUESDAY
AFTERNOON COMPARED TO THIS AFTERNOON. THESE WARMER TEMPS COMBINED
WITH MORE SUN WILL LEAD TO WARMER CONDITIONS...LIKELY BY 5 OR SO
DEGREES.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 249 PM CDT MON AUG 19 2013
HAZARDS...
HEAT INDICES MAY GET CLOSE TO ADVISORY CRITERIA ON WEDNESDAY AND
AGAIN SUNDAY AND MONDAY. ALSO MONITORING POTENTIAL SEVERE WEATHER
FOR LATE WEDNESDAY.
SYNOPTIC OVERVIEW...
TROUGHING ALONG THE WEST COAST OF BRITISH COLUMBIA IS FORECAST
CONCERN NUMBER 1...WITH MODELS STRUGGLING A BIT ON THE AMPLITUDE OF
THE TROUGH AS IT CROSSES SOUTHERN CANADA THE NEXT COUPLE OF DAYS.
SOME PAST GFS RUNS INDICATED THE TROUGH COULD DIP INTO NORTHERN
MINNESOTA LATE WEDNESDAY...WHEREAS THE ECMWF AS WELL AS THE 19.12Z
GFS KEEP IT TO THE NORTH CROSSING NORTHERN ONTARIO. THIS IS
IMPORTANT AS IT IMPACTS HOW FAR SOUTH DYNAMICAL FORCING WILL REACH
INTO THE FORECAST AREA. ADDITIONALLY...THIS SHORTWAVE TROUGH IS
GOING TO DICTATE THE SPEED OF THE COLD FRONT OVER MONTANA...THE
FORCING ON THE FRONT...AND HOW FAR SOUTH THE FRONT GETS HEADING INTO
THURSDAY AND THURSDAY NIGHT. GOOD MODEL AGREEMENT PERSISTS HEADING
INTO NEXT WEEKEND AS THE SUMMER HEAT RIDGE BUILDS AND STRENGTHENS
OVER THE NATIONS HEARTLAND. VERY LITTLE MOVEMENT OF THIS RIDGE IS
SUGGESTED BY MONDAY.
TUESDAY NIGHT THROUGH THURSDAY...
FOCUS IS ON THE COLD FRONT APPROACHING THE AREA. ALL MODELS ARE
SHOWING AN ELEVATED MIX LAYER...I.E. THE WARMER 850MB AND 700MB AIR
PRESENT CURRENTLY OVER THE NORTHERN PLAINS...ADVECTING INTO THE
FORECAST AREA TUESDAY NIGHT AND WEDNESDAY AHEAD OF THE FRONT. THE
EXACT WARMTH IS ONE FACTOR THAT WILL PLAY INTO WHETHER OR NOT THIS
FRONT CAN INITIATE CONVECTION WEDNESDAY AFTERNOON. ANOTHER FACTOR IS
MOISTURE...WHICH THE 19.12Z GFS AND NAM BOTH APPEAR TO BE OVERDOING
THE SURFACE DEWPOINTS. THEY PROG VALUES IN THE 70-75 RANGE WHILE
MIXING AND THE DRYING SOILS SHOULD RESULT IN READINGS MORE IN THE
MID/UPPER 60S. THESE MIXED LAYER DEWPOINTS RESULT IN MLCIN VALUES OF
30-50 J/KG. A THIRD FACTOR OF CONCERN IS LOW LEVEL CONVERGENCE...
WHICH THE NAM AND GFS BOTH PROG WEAK TO NOTHING PRIOR TO THEIR
CONVECTIVE SCHEMES GOING OFF. THUS...THERE IS PLENTY OF UNCERTAINTY
ON THE EXTENT OF POTENTIAL CONVECTION. IN REALITY...THERE IS A
BETTER SHOT FOR CONVECTION ONCE THE FRONT PASSES...DUE TO THE
DEVELOPMENT OF A POST-FRONTAL LOW TO MID LEVEL FRONTOGENESIS ZONE.
HAVE TAILORED PRECIPITATION CHANCES IN THIS WAY WITH HIGHER VALUES
WEDNESDAY NIGHT. PRECIPITATION CHANCES CONTINUE INTO THURSDAY...
MAINLY SOUTH OF I-90...WHERE THE FRONTOGENESIS ZONE MAY STILL BE
LINGERING. THIS IS ALL DEPENDS ON HOW FAR SOUTH THE FRONT MAKES
IT...THOUGH.
FOR SEVERE WEATHER POTENTIAL...THE 0-6KM SHEAR IS SERIOUSLY LAGGING
THE FRONT. 25 KT IS ABOUT THE HIGHEST AT 00Z AND THATS UP NEAR EAU
CLAIRE. 0-3 KM IS NOT MUCH BETTER WITH SIMILAR VALUES. THUS THINKING
THAT IF THERE IS A SEVERE RISK...MORE LIKELY IT IS UP NORTH OF HWY
10 DURING THE LATE AFTERNOON/EVENING HOURS.
ON THE TEMPERATURE SIDE OF THINGS...925MB READINGS FROM THE
ECMWF/GFS ARE PROGGED TO CLIMB TO 24-26C LATE WEDNESDAY. WITH PLENTY
OF SUN MUCH OF THE DAY AND A SOUTHWEST BREEZE...HIGHS SHOULD TOP OUT
BETWEEN THE UPPER 80S AND MID 90S. DEWPOINTS MIXING DOWN INTO THE
MID TO UPPER 60S WILL HELP TO HOLD HEAT INDICES BELOW ADVISORY
CRITERIA. 925MB TEMPS COOLING TO 20-22C FOR THURSDAY LIKELY TO DROP
TEMPS 5-10 DEGREES FROM WEDNESDAY.
THURSDAY NIGHT THROUGH MONDAY...
INITIAL FOCUS FOR THIS TIME PERIOD IS THE RETURN BACK NORTH OF THE
COLD FRONT...I.E. SWITCHING TO A WARM FRONT...AND IF ANY CONVECTION
CAN FIRE ON THAT. THE 19.00Z ECMWF IS THE MOST BULLISH ON FIRING
CONVECTION FOR THURSDAY NIGHT AND FRIDAY AS THE FRONT LIFTS THROUGH
THE FORECAST AREA. 19.12Z GFS/CANADIAN ARE BOTH DRY.
NEXT CONCERN TURNS TO THE HEAT FOR THE WEEKEND INTO MONDAY AS THE
STRONG SUBTROPICAL RIDGE FORMS OVER NEBRASKA...IOWA...KANSAS AND
MISSOURI. THE BULK OF THE HEAT WITH 850MB TEMPS OF 24C OR HIGHER
LOOKS TO STAY WELL OFF TO THE WEST OVER THE DAKOTAS INTO WESTERN
PORTIONS OF NEBRASKA AND KANSAS. HOWEVER...THEY SHOULD STILL TOP OUT
IN THE 18-22C RANGE FOR SATURDAY THROUGH MONDAY...WITH THE HIGHER
READINGS OF 20-22C LIKELY OCCURRING SUNDAY AND MONDAY. THESE ARE
1.5-2 STANDARD DEVIATIONS ABOVE NORMAL...WHICH WOULD IMPLY CLOSE TO
BUT NOT REACHING OR EXCEEDING RECORD HIGHS. LOW TEMPERATURES COULD
TURN OUT QUITE WARM AS WELL WITH A PERSISTENT SOUTH TO SOUTHWEST
BREEZE. INDICATIONS FROM THE 19.12Z ECMWF THAT THE WELL ABOVE NORMAL
TEMPERATURES COULD STICK AROUND WELL BEYOND MONDAY.
PRECIPITATION CHANCES FOR THE WEEKEND INTO EARLY NEXT WEEK SHOULD
STAY CONFINED MOSTLY NORTH OF THE FORECAST AREA...WHERE THE WARM
FRONT FROM THURSDAY NIGHT/FRIDAY WILL BE LOCATED. THERE ARE
POSSIBILITIES THAT THE FRONT COULD SLIP BACK SOUTH INTO NORTHERN
SECTIONS OF THE FORECAST AREA AT TIMES SUNDAY NIGHT AND
MONDAY...THUS HAVE SOME CHANCES IN FOR THIS PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1148 PM CDT MON AUG 19 2013
TRANQUIL...ZONAL FLOW WILL KEEP THINGS RELATIVELY QUIET A COUPLE
MORE DAYS. PASSING...WEAK SHORT WAVE TROUGH HAS LEFT SOME RESIDUAL
MOISTURE IN LOW TO MID LEVELS CREATING SHORT LIVED VFR CEILINGS THIS
EVENING BUT THOSE SHOULD DISSIPATE OVERNIGHT.
SMOKE IN AIRMASS SWEEPING IN FROM WESTERN FOREST FIRES COULD DROP
VISIBILITIES INTO 5-6SM AT TIMES EARLY TUESDAY...OTHERWISE VFR. MORE
DIURNAL CUMULUS POSSIBLE AS WELL WITH STEADY SOUTH TO SOUTHWEST LOW
LEVEL FLOW INTO MID WEEK.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...SHEA
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1105 PM MDT WED AUG 21 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 347 PM MDT WED AUG 21 2013
...FLASH FLOODING/LANDSPOUT THREAT INCREASING...ESPECIALLY FOR
TOMORROW...
CURRENTLY...
SHOWERS AND STORMS ARE MORE ABUNDANT THEN THIS TIME YESTERDAY...WITH
HUNDREDS OF CG STRIKES OCCURRING DURING THE LAST HOUR OVER THE STATE.
A SFC BOUNDARY IS SEEN IN THE MOSAIC RADAR DATA EXTENDING ACROSS
EAST CENTRAL CO AND BECOMING DIFFUSE OVER THE WESTERN PALMER DIVIDE
REGION. TEMPS HAVE RISEN WELL INTO THE 90S ACROSS THE PLAINS...WITH
TEMPS APPROACHING 100 OUT NEAR KLAA.
REST OF TODAY AND TONIGHT...
UPPER MOISTURE WILL CONTINUE TO INCREASE AND EXPECT SCTD SHOWERS AND
STORMS OVER THE HIGHER TRRN THROUGHOUT THIS AFTERNOON. HRRR IS A BIT
AGGRESSIVE OVER THE PIKES PEAK REGION THIS AFTERNOON AND WILL HAVE
TO WATCH THIS AREA FOR FLASH FLOOD PROBLEMS. THE HRRR AGRESSIVENESS
MAY BE IN RESPONSE TO THE BOUNDARY MENTIONED ABOVE. DWPTS HAVE BEEN
MIXING OUT A BIT BUT 30S AND 40S WERE STILL NOTED ACROSS THE
MTNS...WITH 40S AND 50S OVER THE PLAINS. WE WILL ALSO SEE A BETTER
CHANCE OF TSRA OVER THE PLAINS LATE THIS
AFTERNOON/EVENING...ESPECIALLY OVER THE PALMER DVD AND RATON MESA
REGION. WITH THE BOUNDARY OVER THE PALMER...MAY HAVE TO WATCH OUT
FOR A LANDSPOUT...ALBEIT THE PROBABILITY OF THIS IS LOW.
LATER TONIGHT I ANTICIPATE IT TO BE MAINLY DRY WITH PARTLY CLOUDY
SKIES.
THURSDAY...
BY TOMORROW AFTERNOON...BOUNDARY SHOULD LIE FROM KTAD TO NEAR KLAA.
NORTH OF THE FRONT...MOIST UPSLOPE FLOW WILL BE IN PLACE AND WE WILL
SEE A BETTER CHANCE OF STORMS OVER THE PLAINS. WITH THE BOUNDARY
OVER FAR SE CO...A BETTER CHANCE OF A LANDSPOUT TORNADO WILL BE
POSSIBLE...ESPECIALLY CONSIDERING THIS BOUNDARY WILL BE "COOKING"
ALL DAY TOMORROW AND CAPES SHOULD BE ABOUT 1000 J/KG AND WINDS
THROUGHOUT THE COLUMN WILL BE LIGHT.
FLASH FLOOD THREAT OVER THE BURN SCARS WILL BE HIGHER TOMORROW AS
MOISTURE WILL BE MORE ABUNDANT THROUGHOUT THE COLUMN...CAPES WILL BE
ABOUT 1500-2000 ACROSS THE PIKES PEAK REGION AND FLOW WILL BE RATHER
WEAK. THE LOCAL WRF HAS OVER AN INCH OF RAIN OVER THE WALDO LATE
TOMORROW AFTERNOON. CONTEMPLATED ON ISSUING A FLASH FLOOD WATCH BUT
THOUGHT IT BEST TO LET THE MID CREW ISSUE AS THEY WILL HAVE A COUPLE
MORE GUIDANCE RUNS TO LOOK AT.
EXPECT MAX TEMPS TO BE COOLER TOMORROW AS WE WILL SEE MORE CLOUDS
AND LOW LVL MOISTURE OVER THE REGION. HIGHS SHOULD ONLY BE IN THE
90-96F RANGE OVER THE PLAINS...WITH U80S OVER THE PALMER/RATON MESA
REGION. /HODANISH
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 347 PM MDT WED AUG 21 2013
LONGER TERM METEOROLOGICAL ISSUES REMAIN POPS AND TEMPERATURES.
SOME ADJUSTMENTS NEEDED FOR LONGER CYCLE AS UPPER RIDGE IS NOW
PROJECTED TO NOT PUSH AS FAR EAST AS EARLIER INDICATED...MEANING
THAT PRIMARY MOISTURE PLUME SHOULD REMAIN OVER WESTERN PORTIONS OF
THE FORECAST DISTRICT AND POINTS WEST DURING THE LONGER TERM.
THE UPPER RIDGE OF HIGH PRESSURE CENTERED OVER SOUTHERN COLORADO
THIS AFTERNOON IS STILL EXPECTED TO BECOME CENTERED OVER KANSAS
AND OKLAHOMA BY LATER FRIDAY NIGHT BEFORE SHIFTING INTO
MISSOUR(INSTEAD OF OVER ILLINOIS AS SOME PREVIOUS MODEL RUNS HAVE
INDICATED) BY WEDNESDAY.
AS THE UPPER RIDGE PUSHES EAST...FORECAST DISTRICT SHOULD STILL
EXPERIENCE INCREASING ATMOSPHERIC MOISTURE VALUES AT TIMES
...ESPECIALLY OVER WESTERN HIGHER TERRAIN LOCATIONS DURING THE
LONGER TERM.
AT THIS TIME...IT APPEARS THAT THE PRIMARY DEEPER MOISTURE FROM
THE DEEP TROPICS OFF THE WEST COAST OF MEXICO SHOULD REMAIN
FOCUSED OVER THE NEW MEXICO...UTAH AND WESTERN COLORADO REGION FROM
THIS WEEKEND INTO EARLY NEXT WEEK...THEREFORE WESTERN BURN SCARS
SUCH AS THE WEST FORK COMPLEX SHOULD NOTE THE HIGHEST POTENTIAL OF
BURN SCAR FLASH FLOODING DURING THIS TIME-FRAME. WFO PUEBLO WILL
CONTINUE TO MONITOR THIS POTENTIAL TREND CLOSELY.
FINALLY...CONTINUED ABOVE SEASONAL LATE AUGUST TEMPERATURES(ESPECIALLY
EASTERN SECTIONS) AS WELL AS GENERALLY LOW-GRADE GRADIENT WINDS
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1105 PM MDT WED AUG 21 2013
MAINLY VFR CONDITIONS EXPECTED AT TAF SITES THROUGH THE NEXT 24
HOURS. COULD SEE -SHRA AT ALS FOR THE NEXT FEW HOURS AS CONVECTIVE
DEBRIS CLOUDS SLOWLY DIMINISH ACROSS THE STATE THOUGH THE OVERNIGHT.
MONSOONAL MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA
THROUGH THE DAY TOMORROW WITH MORE SCATTERED SHOWERS AND
THUNDERSTORMS EXPECTED ACROSS THE HIGHER TERRAIN IN THE AFTERNOON
AND EVENING HOURS. IN ADDITION...A SECONDARY SURGE OF COOLER AIR
WILL MOVE ACROSS THE EASTERN PLAINS TOMORROW MORNING...WITH LOW LEVEL
MOISTURE INCREASING WITHIN THE DEVELOPING UPSLOPE FLOW. THIS WILL
LEAD TO BETTER CHANCES OF BRIEF MVFR AND IFR CONDITIONS AT COS AFT
20Z WITH LOCALLY HEAVY RAINFALL POSSIBLE.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AVIATION...MW
AREA FORECAST DISCUSSION
NWS TAUNTON MA
330 AM EDT THU AUG 22 2013
.SYNOPSIS...
CONTINUED WARM AND MUGGY CONDITIONS AHEAD OF A SERIES OF WET
WEATHER DISTURBANCES TODAY INTO FRIDAY. SCATTERED SHOWERS AND
THUNDERSTORMS EXPECTED...CLEARING OUT BY AS LATE AS FRIDAY NIGHT.
THEREAFTER DRY AND NEAR SEASONABLE WEATHER WILL RETURN THIS
WEEKEND AS HIGH PRESSURE BUILDS ACROSS THE REGION. MORE HUMID
CONDITIONS AND PERIODS OF UNSETTLED WEATHER MOVES IN NEXT WEEK AS
A WARM FRONT MOVES INTO THE REGION.
&&
.NEAR TERM /THROUGH TODAY/...
4 AM UPDATE...
SCATTERED SHOWER AND THUNDERSTORM ACTIVITY ACROSS NORTHEAST
PENNSYLVANIA COLLOCATED WITHIN A REGION OF FAVORABLE ENHANCED
ASCENT AND PERHAPS SOME LOCALIZED CONVERGENCE OF LOW-LEVEL WINDS
SHOULD GRADUALLY PUSH EASTWARD...BUT PERHAPS BECOMING DELAYED BY
OVERWHELMING DRY AIR ACROSS THE FORECAST REGION.
HRRR IS NOT FORECASTING OUTCOMES VERY WELL WITH LATEST GUIDANCE.
WOULD ASSUME THE BETTER ACTIVITY REMAINS SOUTH AND WEST PRIOR TO
THE MORNING HOURS. DURING SUCH TIME...LOW CLOUDS AND FOG WILL
CONTINUE TO HAMPER THE SOUTH COAST WITH VISIBILITIES DOWN TO A
HALF A MILE OR LESS.
TODAY...
FOCUS WILL BE ON THE DEAMPLIFYING MID-LEVEL LOW PRESSURE TRACKING
EAST ACROSS THE DELMARVA OUT TO SEA. SQUEEZING UP AGAINST ATLANTIC
HIGH PRESSURE AND PUSHED BY A STRONGER SHORTWAVE AND TROUGH AXIS
APPROACHING FROM THE EASTERN GREAT LAKES WILL YIELD AMPLIFICATION OF
MID- TO UPPER-LEVEL TROPOSPHERIC WINDS PROMOTING GREATER DIFFLUENCE
ALOFT. IN RESPONSE...SHOULD SEE AN ENHANCEMENT OF SOUTHERLY FLOW
WITHIN THE LOW-LEVELS ADVECTING MORE MUGGY CONDITIONS INTO SOUTHERN
NEW ENGLAND AGAINST DRIER AIR /GUSTS UP TO 20 MPH ALONG THE SOUTH
COAST/. SUBSEQUENT MOISTENING TO THE WET-BULB OF THE ATMOSPHERIC
PROFILE SHOULD ALLOW THE BUILD UP OF ELEVATED INSTABILITY.
FEEL ANY ACTIVITY TODAY WILL BE LOCALIZED MAINLY SOUTH AND WEST IN
REGIONS OF FAVORABLE LIFT ALOFT COLLOCATED WITH AREAS OF LOW-LEVEL
CONVERGENCE THAT CAPITALIZE ON THE GROWING INSTABILITY...ESPECIALLY
IF THE BOUNDARY LAYER HAS AN OPPORTUNITY TO DESTABILIZE. STILL
DIFFICULT TO PIN-POINT...BUT FEEL AREAS NORTH AND EAST MAY REMAIN
UNDER THE INFLUENCE OF DRIER AND SINKING AIR.
GREATER CONFIDENCE WITH THE LATEST HRRR AND 22.0Z NAM HIGHLIGHTING
SOME EARLY MORNING ACTIVITY COLLOCATED WITH THE NOSE OF A LOW-LEVEL
JET AXIS JUST ABOVE THE DECOUPLED BOUNDARY LAYER. ACTIVITY OCCURRING
ACROSS NORTHEAST PENNSYLVANIA SHOULD FOCUS EASTWARD WITH TIME. BUT
OTHERWISE...A MAJORITY OF THE FORECAST AREA MAY SIMPLY REMAIN PARTLY
CLOUDY AND DRY...ALLOWING HIGHS TO GET INTO THE MID- TO UPPER-80S...
WITH A FEW LOCATIONS AT OR ABOVE THE 90 DEGREE MARK FOR A SECOND DAY
IN A ROW.
CONSIDERING A WEAK SHEAR ENVIRONMENT WITH MODEST INSTABILITY ALONG
WITH NEAR-ZERO CORFIDI VECTORS AND A WEAK MEAN ATMOSPHERIC FLOW
AROUND 15 MPH...MAIN THREATS ASSOCIATED WITH ANY STORMS APPEAR TO
BE HEAVY RAIN AND POSSIBLE NUISANCE FLOODING /PWATS CONTINUE TO
RANGE AROUND 1.5 TO 1.75 INCHES/. COULD SEE SOME GUSTY WINDS
SHOULD THE BOUNDARY LAYER MIX-OUT WITH INVERTED-V PROFILES.
ACTIVITY ALONG THE UPSTREAM COLD FRONT WILL NOT PUSH INTO THE
FORECAST REGION UNTIL EVENING.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
TONIGHT...
STRONGER SHORTWAVE AND TROUGH AXIS WITH ATTENDANT SURFACE COLD FRONT
WILL SWEEP THROUGH THE REGION REACHING SOUTHEAST MASSACHUSETTS BY
MORNING. ANTICIPATING SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF
THE COLD FRONT AIDED BY STRONG FRONTOGENETICAL LIFT. INITIALLY
PUSHING INTO WESTERN NEW ENGLAND BY EVENING...ACTIVITY LOOKS TO
DIMINISH EASTWARD TOWARDS BY MIDNIGHT INTO MORNING AS BETTER
DYNAMICS ALOFT LIFT NORTH AND EAST PARENT WITH THE MID-LEVEL LOW.
WITH A STABILIZING BOUNDARY LAYER PROFILE...FEEL ANY STORMS WILL BE
MAINLY ASSOCIATED WITH HEAVY RAIN. LESSER CONFIDENCE FOR NUISANCE
FLOODING AS THE BETTER PWAT ENVIRONMENT WILL BE WELL SOUTH AND EAST
OFFSHORE OF THE REGION. LOWS AROUND THE MID-60S.
FRIDAY...
SURFACE COLD FRONT SLOWS OFFSHORE...STALLING SOUTH OF SOUTHERN NEW
ENGLAND. CLOUDS AND SHOWERS WILL LINGER FOR THE FAR SOUTH-SOUTHEAST
PORTIONS OF THE FORECAST AREA. NORTHWEST FLOW PREVAILS PUSHING
COOLER AND DRIER AIR SOUTH WITHIN THE LOW- TO MID-LEVELS.
EXPECTING DEEP BOUNDARY LAYER MIXING UP TO H8 LENDING TO SCATTERED
TO BROKEN DIURNAL CUMULUS AND THE POSSIBILITY FOR SOME SPOTTY
SHOWERS CAPITALIZING ON THE LIFT OF MINOR ELEVATED INSTABILITY AHEAD
OF A REINFORCING SECONDARY COLD FRONT. WILL INSERT SLIGHT CHANCE
POPS FOR A MAJORITY OF THE FORECAST REGION FOR THE MIDDAY INTO
AFTERNOON PERIOD. WILL ALSO SEE THE MIX-DOWN OF DRIER AIR AND FASTER
MOMENTUM. WIND GUSTS AROUND 15 MPH EXPECTED WITH HIGHS AROUND THE
LOW-80S...COOLER ALONG THE SHORES AND HIGHER ELEVATIONS.
FRIDAY NIGHT...
REINFORCING COLD FRONT PUSHES WELL OFFSHORE PARENT WITH ANOTHER MID-
LEVEL TROUGH AXIS SWEEPING ACROSS NEW ENGLAND. WINDS BACK MORE
NORTHERLY CONTINUALLY ADVECTING MORE COOLER AND DRIER AIR SOUTHWARD
OUT OF CANADA. LOOKING AT A POTENTIALLY CHILLY NIGHT SHOULD
CONDITIONS REMAIN MOSTLY CLEAR. LOWS AROUND THE MID-50S.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
HIGHLIGHTS...
* DRY AND COOLER SAT...THEN WARMER SUNDAY
* BECOMING MORE HUMID NEXT WEEK WITH UNSETTLED WEATHER POSSIBLE FROM
TIME TO TIME.
OVERVIEW...
GUIDANCE IN GOOD AGREEMENT ON OVERALL PATTERN DURING THE EXTENDED
PERIOD. MID LEVEL TROF WHICH WILL BRING COOLER WEATHER TO START THE
WEEKEND WILL BE EXITING THE REGION BY SUNDAY. MODELS AGREE ON AN
ANOMALOUS AND EXPANSIVE MID LEVEL RIDGE BUILDING ACROSS THE CENTRAL
CONUS DURING MUCH OF THE PERIOD WITH SNE REMAINING ON THE SOUTHERN
EDGE OF THE POLAR JET WITH MAINLY NW FLOW ALOFT. THIS WILL KEEP THE
SIGNIFICANT HEAT WEST OF SNE AND ALSO MAKE US SUSCEPTIBLE TO
OCCASIONAL IMPULSES IN NW FLOW BEGINNING NEXT WEEK. THE TIMING AND
AMPLITUDE OF INDIVIDUAL SHORTWAVES WILL DETERMINE THE COVERAGE AND
INTENSITY OF SHOWERS AND THUNDERSTORMS...BUT THE THREAT WILL EXIST
SOMETIME FROM LATE MON INTO WED.
SATURDAY AND SUNDAY...
STRONG HIGH PRES BUILDS ACROSS SNE GRADUALLY SHIFTING TO THE S ON
SUNDAY. FOR SAT...NEARBY MID LEVEL TROF AND COLD POOL ACTING ON LOW
LEVEL MOISTURE WILL LIKELY BRING AT LEAST SCT-BKN CU BUT THE
MOISTURE IS SHALLOW SO DRY WEATHER EXPECTED. LESS CU ON SUNDAY AS
MID LEVEL TEMPS WARM. TEMPS WILL BE A FEW DEGREES BELOW NORMAL
SAT...MOSTLY IN THE MID/UPPER 70S THEN WARMING INTO UPPER 70S AND
LOWER 80S SUNDAY IN RESPONSE TO INCREASING MID LEVEL TEMPS.
MONDAY...
SOME DIFFERENCES BETWEEN GFS AND ECMWF BEGIN TO SHOW UP REGARDING
THE EASTWARD EXTENT OF THE WARM FRONT. GFS APPEARS TO MOVE THE WARM
FRONT THROUGH TOO QUICKLY. PREFER THE ECMWF KEEPING THE FRONT TO THE
WEST GIVEN THE NW FLOW ALOFT. MOST OF THE REGION SHOULD REMAIN DRY
ALTHOUGH CANT RULE OUT A FEW SHOWERS OR A THUNDERSTORM ACROSS W
ZONES LATE IN THE DAY AS MOISTURE INCREASES FROM THE WEST.
MONDAY NIGHT INTO WEDNESDAY...
IT APPEARS FRONTAL BOUNDARY MAY GET HUNG UP NEAR SNE DURING THIS
PERIOD. THIS WILL BRING THE THREAT OF SHOWERS AND THUNDERSTORMS FROM
TIME TO TIME BUT WE HAVE LOW CONFIDENCE IN TIMING AS THERE ARE
DIFFERENCES IN THE MODELS. HUMIDITY WILL BE INCREASING ALTHOUGH THE
HEAT WILL REMAIN TO THE WEST WITH TEMPS MOSTLY NEAR SEASONABLE
NORMALS.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH FRIDAY NIGHT/...MODERATE CONFIDENCE.
PREVAILING VFR WITH IFR CIGS/VSBYS ALONG THE SOUTH-SHORE GRADUALLY
DISSIPATING INTO THE MIDDAY HOURS. SHRA/TSRA WILL BE ON THE
INCREASE FROM THE SOUTH AND WEST. MENTIONED VCSH FOR NOW WITH
OVERWHELMING UNCERTAINTY ON THE EVOLUTION AND POTENTIAL IMPACTS OF
SHRA/TSRA. SOUTHWEST WINDS PREVAILING WITH GUSTS UP TO AROUND 20
KTS.
ACTIVITY CLEARS UP INTO FRIDAY MORNING WITH A COLD FRONT SWEEPING
ACROSS THE TERMINALS...WINDS BACKING WEST-NORTHWEST. MAY SEE A
SPOT SHRA/TSRA DURING THE DAY FRIDAY...BUT A REINFORCING COLD
FRONT WITH NORTH-NORTHWEST FLOW TO THE REAR SHOULD PUSH ALL
REMAINING ACTIVITY OFFSHORE.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. NO EXPECTATION FOR A SEA-
BREEZE.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF. SHRA/TSRA POSSIBLE BY THE
LATE MORNING HOURS CONTINUING THROUGH THE DAY.
OUTLOOK...SATURDAY THROUGH MONDAY...
HIGH CONFIDENCE. MOSTLY VFR WITH SCT-BKN DIURNAL CU. LATE
NIGHT/EARLY MORNING PATCHY MVFR/IFR FOG POSSIBLE IN THE CT VALLEY.
WIDELY SCT SHOWERS/TSTMS POSSIBLE WESTERN AREAS LATE MON.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH FRIDAY NIGHT/...MODERATE CONFIDENCE.
WINDS AND SEAS TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS. WORTHY
OF MENTION THAT SOUTHWEST WINDS WILL INCREASE WITH GUSTS UP TO 20
KTS POSSIBLE TODAY MAINLY ALONG THE SOUTH SHORE. SHOWERS AND
THUNDERSTORMS MAY BE ON THE INCREASE AHEAD OF A SURFACE COLD FRONT
ANTICIPATED TO SWEEP INTO THE WATERS CLOSER TO FRIDAY MORNING AND
CLEARING OUT BY FRIDAY LATE. BEHIND THE FRONT...WINDS WILL BACK
OUT OF THE NORTHWEST.
OUTLOOK...SATURDAY THROUGH MONDAY...
HIGH CONFIDENCE.
EXPECT WINDS AND SEAS TO REMAIN BELOW SCA THRESHOLDS FOR MOST OF THE
PERIOD. HOWEVER...SW WINDS COULD GUST TO 20+ KTS MON/MON NIGHT WITH
SEAS POSSIBLY BUILDING TO 5 FT OVER OUTER SOUTHERN WATERS.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KJC/SIPPRELL
NEAR TERM...SIPPRELL
SHORT TERM...SIPPRELL
LONG TERM...KJC
AVIATION...KJC/SIPPRELL
MARINE...KJC/SIPPRELL
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
417 AM CDT THU AUG 22 2013
.DISCUSSION...
329 AM CDT
THE PRIMARY FORECAST CHALLENGES ARE CHANCES FOR STORMS TODAY AND
EARLY THIS EVE FOLLOWED BY THE HEAT...POTENTIALLY
PROLONGED...DURING NEXT WEEK.
THIS MORNING...A SOMEWHAT TRUBULENET...DISORGANIZED...AND EVEN
OVERTURNED ATMOSPHERE IS IN PLACE WITH ONE MCS HAVING GONE
THROUGH LATE LAST NIGHT ACROSS LAKE MI...WITH OUTFLOW STILL
PROGRESSING SOUTHEAST ACROSS THE CWA AS OF 315 AM. THIS IS
TRIGGERING A FEW STORMS THOUGH NOTHING ROBUST. FURTHER WEST AN MCS
EVOLVING EASTWARD ACROSS NORTHERN IA ALONG THE FRONTAL
BOUNDARY...WHICH IS VERY DIFFUSE EARLY TODAY...LOOKS TO WORK
EASTWARD WITHIN THE INSTABILITY MAXIMUM THROUGH THE MORNING. IN
ADVANCE OF THIS...NEAR THE BOUNDARY...THERE HAVE BEEN SOME
ISOLATED STORMS WITHIN THE HIGH PWAT AIR AND GENTLE WARM AIR
ADVECTION BUMPING UP AGAINST THE FRONT. SO ALL OF THIS LIKELY WILL
RESULT IN CONTINUED ISOLATED TO SCATTERED STORM GENERATION THIS
MORNING.
THIS AFTERNOON AND EVENING...WHILE THE IA MCS IS LIKELY TO BEGIN
DECAYING SOME LATER THIS MORNING GIVEN LIMITED DEEP LAYER
SHEAR...REMNANTS OF WHAT IS LEFT ALONG WITH A FORECAST
CONVECTIVELY ENHANCED WAVE BY THE RAP WILL MOVE INTO THE WESTERN
CWA LATE THIS MORNING/EARLY THIS AFTERNOON. THE POTENTIAL FOR THIS
TO RE-INSTIGATE STORMS IS CERTAINLY THERE WITH THE UNSTABLE AIR
MASS STILL IN PLACE AND NOT EXPECTED TO VACATE UNTIL THIS EVE DUE
TO THE SLOW COOL FRONTAL APPROACH FROM THE NORTH. MLCAPE VALUES
OF 1500-3000 J/KG ARE FORECAST BY THE NAM TO BUILD ACROSS THE
WESTERN AND SOUTHERN CWA...BASICALLY IN THOSE AREAS AWAY FROM THE
STABILIZING ONSHORE COMPONENT OFF THE LAKE. GIVEN LITTLE
INHIBITION THE TRIGGER OF THIS IMPULSE/MCV COULD BE ENOUGH TO
SPARK STORMS AND THE SUITE OF CONVECTIVE ALLOWING GUIDANCE HAS
MEMBERS THAT DO JUST THAT. SO HAVE INCREASED POPS SOME INCLUDING
HOLDING ONTO THEM LONGER. COULD CONCEIVABLY SEE SOME STORMS LINGER
INTO THE EVE...NAMELY SOUTH OF I-80. WITH LIMITED UPPER FORCING
AND DYNAMICS THE POTENTIAL FOR ORGANIZATION TOWARD ROBUST STORMS
REMAINS PRIMARILY LOW...THOUGH A FEW ISOLATED NEAR TO SEVERE
STORMS MAY DEVELOP. TEMPERATURES TODAY LOOK TO PEAK IN THE MID 80S
IN THOSE AREAS AWAY FROM THE LAKE WHERE AN ONSHORE COMPONENT WILL
INCREASE THIS AFTERNOON. HIGHS LAKESIDE LOOK TO BE IN THE UPPER
70S.
QUIET WEATHER IS EXPECTED FRI AND SAT WITH HIGHS AROUND NORMAL.
DEW POINTS IN THE 40S STILL LOOK PLAUSIBLE FRI AFTERNOON FOR
SEVERAL AREAS. FRI NIGHT LOOKS CLEAR AND CALM WITH HIGH
CONFIDENCE SO CONTINUE TO ADVERTISE LOWER TO MID 50S IN MOST
OUTLYING AREAS.
NEXT WEEK IS THE FINAL WEEK OF METEOROLOGICAL SUMMER AND IT IS
SHAPING UP TO BE EVERY BIT SUMMER...AT LEAST THE FIRST HALF OF
IT BUT POSSIBLY MUCH OF IT. WITH THE CURRENT TROUGH OVER CANADA
ONLY GIVING A GLANCING BLOW...THE RIDGE BUILDS BACK NORTHWARD
ACROSS THE CENTRAL TO EASTERN PARTS OF THE COUNTRY BY LATE IN THE
WEEKEND. DPROG/DTS FROM BOTH THE EC AND GFS HAVE INDICATED A
FURTHER NORTH 500MB RIDGE CENTER IN THE PAST 24 HOURS...AND THIS
HAS RESULTED IN A WARMING GUIDANCE TREND. THE 594DM RIDGE
PLACEMENT JUST TO THE WEST...MODEST AND WARM SW/WSW 850-925MB
FLOW...AND A DRY COLUMN IS A PATTERN CONDUCIVE FOR WIDESPREAD
LOWER-MID 90S MON AND TUE WITH THE 90 THRESHOLD LIKELY REACHED IN
PLACES ON SUN. THE JET IS ADVERTISED TO BE ACTIVE ON THE NORTH SIDE
OF THIS WITH BROAD LOW PRESSURE ACROSS THE HIGH PLAINS LIKELY
RESULTING IN MULTIPLE MCS DEVELOPMENT IF THIS PATTERN IS CORRECT.
AT THIS TIME...THESE ARE EXPECTED TO REMAIN NORTH BUT DEPENDING ON
FREQUENCY OF THEM LIKELY WILL DICTATE HOW FAR AND QUICKLY SOUTH
THE SURFACE BOUNDARY ADVANCES. WITH NO REAL DEW POINT SCOURING TO
OUR SOUTH FROM OUR CURRENT BOUNDARY...THESE SHOULD REBOUND TO AT
LEAST THE UPPER 60S BY MON AND HOLD TO SLIGHTLY INCREASE AS LONG
AS THE HEAT PERSISTS. BY TUE THIS RESULTS IN FORECAST HEAT INDICES
AT 100 TO 105 IN SOME PLACES /NOT CHICAGO AT THIS TIME/. WHILE
THIS PERIOD IS STILL NUMEROUS DAYS OUT...THERE SEEM TO BE A
LIMITED SET OF FACTORS PRIOR TO WED THAT COULD REALLY BOTCH UP THE
HEAT GIVEN THE AMPLITUDE OF THE RIDGE. WILL CONTINUE TO HIGHLIGHT
IN THE HWO.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* CONVECTIVE TRENDS OVER THE NEXT SEVERAL HOURS...AND AGAIN LATE
THIS MORNING AND EARLY AFTERNOON.
* WIND SHIFTING TO NORTH ONCE AGAIN LATE THURSDAY MORNING WITH A
COLD FRONT.
* POTENTIAL FOR MVFR CIGS BEHIND THE FRONT.
BMD
//DISCUSSION...UPDATED 09Z...
ADDITIONAL THUNDERSTORMS ARE DEVELOPING EARLY THIS MORNING WITHIN
A CORRIDOR OF UPWARDS OF 2000 J/KG MUCAPE THAT STRETCHES FROM
ROUGHLY NORTH CENTRAL IOWA INTO FAR NORTHERN ILLINOIS. COVERAGE IS
SOMEWHAT SCATTERED AT THE MOMENT AND EXPECT THIS TO REMAIN THE
CASE THROUGH THE EARLY MORNING. A CONVECTIVE COMPLEX MOVING EAST
ACROSS NORTH CENTRAL IOWA SHOWING SIGNS OF DEVELOPING AN MCV WHICH
IS EXPECTED TO MOVE INTO NORTH CENTRAL ILLINOIS AROUND 14Z AND
NORTHEAST ILLINOIS AROUND 15Z. IT IS QUITE POSSIBLE THAT THIS
COULD SPAWN ADDITIONAL THUNDERSTORMS OVER THE AREA 1-2 HOURS PRIOR
TO ITS ARRIVAL...THOUGH QUITE A BIT OF UNCERTAINTY STILL IN
EXACTLY WHERE THIS MAY DEVELOP WITH RESPECT TO THE TERMINALS...AND
COVERAGE.
PREVIOUS DISCUSSION...
SEVERAL CONCERNS IN THE SHORT TERM REVOLVING AROUND A COUPLE DIFFERENT
WINDOWS OF OPPORTUNITY FOR SHRA/TSRA...AND WIND DIRECTION WITH AN
OUTFLOW BOUNDARY RACING SOUTH DOWN LAKE MICHIGAN.
RADAR AND SATELLITE TRENDS INDICATE THAT CONVECTIVE ACTIVITY AND
COVERAGE IS GENERALLY ON DOWNWARD TREND. SEEMS REASONABLE FOR THIS
TREND TO CONTINUE AS WE FALL BEHIND A WAVE THAT IS MOVING AWAY FROM
THE AREA ACROSS LAKE MICHIGAN. THE LOW LEVEL JET SETS UP WELL TO OUR
WEST AND WOULD SUPPORT ONGOING CONVECTION OVER NEBRASKA/WESTERN
IOWA...BUT NOT LOCALLY.
ON AVERAGE...IR IMAGERY SHOWS WARMING CLOUD TOPS OVER THE
AREA...WITH THE COOLEST CLOUD TOPS BECOMING MUCH MORE ISOLATED. THE
AREA CURRENTLY OVER THE CHICAGO TERMINALS HAS LOST MOST OF ITS
LIGHTNING...EXCEPT ON THE SOUTHERN MOST STORMS WHICH WILL NOT IMPACT
THE TERMINALS. EXPECT THAT BY THE TIME THE 06Z TAFS GO INTO EFFECT
THIS AREA WILL BE SOUTH OF ORD...AND SHOULD CLEAR MDW BY 0630Z. NEXT
AREA OF CONCERN IS AN AREA OVER NORTHWEST ILLINOIS. IF THIS AREA
HOLDS TOGETHER...EXPECT IT TO BE THROUGH THE CHICAGO TERMINALS BY
AROUND 09Z. GIVEN THE DOWNWARD TRENDS THOUGH DO NOT ANTICIPATE THIS
TO IMPACT BEYOND RFD WHICH SHOULD CLEAR BY 730Z.
TO OUR NORTH...AN OUTFLOW BOUNDARY IS EVIDENT ON RADAR IMAGERY
RACING SOUTH ALONG THE COAST OF LAKE MICHIGAN. THE CONVECTION TO
SUSTAIN THIS PUSH DOWN THE LAKE HAS SHIFTED EAST OF THE
BOUNDARY...WHICH IS STRUGGLING TO PUSH VERY FAR INLAND...BUT THERE
ARE CURRENTLY NORTHEAST GUSTS OF AROUND 20-25 KTS ASSOCIATED WITH
THE BOUNDARY. WINDS ARE EXPECTED TO SHIFT NORTHEAST AND INCREASE
SHARPLY...THEN SHOULD SETTLE DOWN SHORTLY THEREAFTER AND RETURN
CLOCKWISE BACK TO A MORE SOUTHERLY WIND...AND EVENTUALLY
SOUTHWEST. BASED ON THE CURRENT TRAJECTORY...IT WILL BE NEAR
ORD...MDW...AND GYY BY 630Z.
DID NOT MAKE ANY BIG CHANGES BEYOND THE FIRST 6 HOURS OF THE TAF.
FRONTAL TIMING STILL APPEARS TO BE AROUND 14Z WITH WINDS SHIFTING
TO NORTH...THEN NORTHEAST BEHIND THE FRONT. CANT COMPLETELY RULE
OUT ADDITIONAL THUNDERSTORMS DEVELOPING NEARBY TOMORROW AS WE
QUICKLY DEVELOP MODERATE INSTABILITY OVER THE AREA...BUT IT
APPEARS THE BEST FORCING WILL SHIFT SOUTH OF THE TERMINALS. SOME
MODEL SOUNDINGS CONTINUE TO INDICATE THE POTENTIAL FOR MVFR CIGS
TO DEVELOP RIGHT BEHIND THE FRONT FOR A COUPLE HOURS...THOUGH MOS
GUIDANCE INDICATES CONDITIONS WILL REMAIN VFR BEHIND THE FRONT.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* LOW CONFIDENCE IN TSRA TRENDS THROUGH THE MORNING.
* LOW CONFIDENCE IN MVFR CIGS BEHIND FRONT.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR. NORTHEAST WINDS.
SATURDAY...VFR. EASTERLY WINDS.
SUNDAY THROUGH TUESDAY...VFR.
RC
&&
.MARINE...
250 AM CDT
LOW PRESSURE OF 29.1 INCHES LIES OVER FAR NORTHERN QUEBEC WITH A
COLD FRONT SAGGING TO THE SOUTHWEST ACROSS THE UPPER PENINSULA OF
MICHIGAN AND INTO CENTRAL WISCONSIN. THIS FRONT WILL CONTINUE TO
MOVE SOUTH ACROSS LAKE MICHIGAN THIS MORNING. THE FRONT SHOULD BE
SOUTH OF LAKE MICHIGAN THIS AFTERNOON AS HIGH PRESSURE OF 30.2
INCHES BUILDS ACROSS THE UPPER MIDWEST. THE HIGH WILL SHIFT EAST
OVER LAKE MICHIGAN ON FRIDAY...THEN OVER THE EASTERN LAKES
SATURDAY. A BROAD AREA OF LOW PRESSURE AVERAGING 29.7 INCHES WILL
DEVELOP OVER THE NORTHERN PLAINS AND CANADIAN PRAIRIES SUNDAY AND
MONDAY...AND SLOWLY SHIFT EAST ACROSS THE GREAT LAKES THROUGH
MIDWEEK.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
330 AM CDT THU AUG 22 2013
.DISCUSSION...
329 AM CDT
THE PRIMARY FORECAST CHALLENGES ARE CHANCES FOR STORMS TODAY AND
EARLY THIS EVE FOLLOWED BY THE HEAT...POTENTIALLY
PROLONGED...DURING NEXT WEEK.
THIS MORNING...A SOMEWHAT TRUBULENET...DISORGANIZED...AND EVEN
OVERTURNED ATMOSPHERE IS IN PLACE WITH ONE MCS HAVING GONE
THROUGH LATE LAST NIGHT ACROSS LAKE MI...WITH OUTFLOW STILL
PROGRESSING SOUTHEAST ACROSS THE CWA AS OF 315 AM. THIS IS
TRIGGERING A FEW STORMS THOUGH NOTHING ROBUST. FURTHER WEST AN MCS
EVOLVING EASTWARD ACROSS NORTHERN IA ALONG THE FRONTAL
BOUNDARY...WHICH IS VERY DIFFUSE EARLY TODAY...LOOKS TO WORK
EASTWARD WITHIN THE INSTABILITY MAXIMUM THROUGH THE MORNING. IN
ADVANCE OF THIS...NEAR THE BOUNDARY...THERE HAVE BEEN SOME
ISOLATED STORMS WITHIN THE HIGH PWAT AIR AND GENTLE WARM AIR
ADVECTION BUMPING UP AGAINST THE FRONT. SO ALL OF THIS LIKELY WILL
RESULT IN CONTINUED ISOLATED TO SCATTERED STORM GENERATION THIS
MORNING.
THIS AFTERNOON AND EVENING...WHILE THE IA MCS IS LIKELY TO BEGIN
DECAYING SOME LATER THIS MORNING GIVEN LIMITED DEEP LAYER
SHEAR...REMNANTS OF WHAT IS LEFT ALONG WITH A FORECAST
CONVECTIVELY ENHANCED WAVE BY THE RAP WILL MOVE INTO THE WESTERN
CWA LATE THIS MORNING/EARLY THIS AFTERNOON. THE POTENTIAL FOR THIS
TO RE-INSTIGATE STORMS IS CERTAINLY THERE WITH THE UNSTABLE AIR
MASS STILL IN PLACE AND NOT EXPECTED TO VACATE UNTIL THIS EVE DUE
TO THE SLOW COOL FRONTAL APPROACH FROM THE NORTH. MLCAPE VALUES
OF 1500-3000 J/KG ARE FORECAST BY THE NAM TO BUILD ACROSS THE
WESTERN AND SOUTHERN CWA...BASICALLY IN THOSE AREAS AWAY FROM THE
STABILIZING ONSHORE COMPONENT OFF THE LAKE. GIVEN LITTLE
INHIBITION THE TRIGGER OF THIS IMPULSE/MCV COULD BE ENOUGH TO
SPARK STORMS AND THE SUITE OF CONVECTIVE ALLOWING GUIDANCE HAS
MEMBERS THAT DO JUST THAT. SO HAVE INCREASED POPS SOME INCLUDING
HOLDING ONTO THEM LONGER. COULD CONCEIVABLY SEE SOME STORMS LINGER
INTO THE EVE...NAMELY SOUTH OF I-80. WITH LIMITED UPPER FORCING
AND DYNAMICS THE POTENTIAL FOR ORGANIZATION TOWARD ROBUST STORMS
REMAINS PRIMARILY LOW...THOUGH A FEW ISOLATED NEAR TO SEVERE
STORMS MAY DEVELOP. TEMPERATURES TODAY LOOK TO PEAK IN THE MID 80S
IN THOSE AREAS AWAY FROM THE LAKE WHERE AN ONSHORE COMPONENT WILL
INCREASE THIS AFTERNOON. HIGHS LAKESIDE LOOK TO BE IN THE UPPER
70S.
QUIET WEATHER IS EXPECTED FRI AND SAT WITH HIGHS AROUND NORMAL.
DEW POINTS IN THE 40S STILL LOOK PLAUSIBLE FRI AFTERNOON FOR
SEVERAL AREAS. FRI NIGHT LOOKS CLEAR AND CALM WITH HIGH
CONFIDENCE SO CONTINUE TO ADVERTISE LOWER TO MID 50S IN MOST
OUTLYING AREAS.
NEXT WEEK IS THE FINAL WEEK OF METEOROLOGICAL SUMMER AND IT IS
SHAPING UP TO BE EVERY BIT SUMMER...AT LEAST THE FIRST HALF OF
IT BUT POSSIBLY MUCH OF IT. WITH THE CURRENT TROUGH OVER CANADA
ONLY GIVING A GLANCING BLOW...THE RIDGE BUILDS BACK NORTHWARD
ACROSS THE CENTRAL TO EASTERN PARTS OF THE COUNTRY BY LATE IN THE
WEEKEND. DPROG/DTS FROM BOTH THE EC AND GFS HAVE INDICATED A
FURTHER NORTH 500MB RIDGE CENTER IN THE PAST 24 HOURS...AND THIS
HAS RESULTED IN A WARMING GUIDANCE TREND. THE 594DM RIDGE
PLACEMENT JUST TO THE WEST...MODEST AND WARM SW/WSW 850-925MB
FLOW...AND A DRY COLUMN IS A PATTERN CONDUCIVE FOR WIDESPREAD
LOWER-MID 90S MON AND TUE WITH THE 90 THRESHOLD LIKELY REACHED IN
PLACES ON SUN. THE JET IS ADVERTISED TO BE ACTIVE ON THE NORTH SIDE
OF THIS WITH BROAD LOW PRESSURE ACROSS THE HIGH PLAINS LIKELY
RESULTING IN MULTIPLE MCS DEVELOPMENT IF THIS PATTERN IS CORRECT.
AT THIS TIME...THESE ARE EXPECTED TO REMAIN NORTH BUT DEPENDING ON
FREQUENCY OF THEM LIKELY WILL DICTATE HOW FAR AND QUICKLY SOUTH
THE SURFACE BOUNDARY ADVANCES. WITH NO REAL DEW POINT SCOURING TO
OUR SOUTH FROM OUR CURRENT BOUNDARY...THESE SHOULD REBOUND TO AT
LEAST THE UPPER 60S BY MON AND HOLD TO SLIGHTLY INCREASE AS LONG
AS THE HEAT PERSISTS. BY TUE THIS RESULTS IN FORECAST HEAT INDICES
AT 100 TO 105 IN SOME PLACES /NOT CHICAGO AT THIS TIME/. WHILE
THIS PERIOD IS STILL NUMEROUS DAYS OUT...THERE SEEM TO BE A
LIMITED SET OF FACTORS PRIOR TO WED THAT COULD REALLY BOTCH UP THE
HEAT GIVEN THE AMPLITUDE OF THE RIDGE. WILL CONTINUE TO HIGHLIGHT
IN THE HWO.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* CONVECTIVE TRENDS OVER THE NEXT SEVERAL HOURS.
* TEMPORARY WIND SHIFT TO THE NORTHEAST WITH WINDS GUSTING TO
AROUND 20 KT FOR A SHORT PERIOD.
* WIND TRENDS OVERNIGHT BEHIND OUTFLOW BOUNDARY...AND SHIFTING TO
NORTH ONCE AGAIN THURSDAY MORNING WITH A COLD FRONT.
* POTENTIAL FOR MVFR CIGS BEHIND THE FRONT.
BMD
//DISCUSSION...UPDATED 06Z...
SEVERAL CONCERNS IN THE SHORT TERM REVOLVING AROUND A COUPLE DIFFERENT
WINDOWS OF OPPORTUNITY FOR SHRA/TSRA...AND WIND DIRECTION WITH AN
OUTFLOW BOUNDARY RACING SOUTH DOWN LAKE MICHIGAN.
RADAR AND SATELLITE TRENDS INDICATE THAT CONVECTIVE ACTIVITY AND
COVERAGE IS GENERALLY ON DOWNWARD TREND. SEEMS REASONABLE FOR THIS
TREND TO CONTINUE AS WE FALL BEHIND A WAVE THAT IS MOVING AWAY FROM
THE AREA ACROSS LAKE MICHIGAN. THE LOW LEVEL JET SETS UP WELL TO OUR
WEST AND WOULD SUPPORT ONGOING CONVECTION OVER NEBRASKA/WESTERN
IOWA...BUT NOT LOCALLY.
ON AVERAGE...IR IMAGERY SHOWS WARMING CLOUD TOPS OVER THE
AREA...WITH THE COOLEST CLOUD TOPS BECOMING MUCH MORE ISOLATED. THE
AREA CURRENTLY OVER THE CHICAGO TERMINALS HAS LOST MOST OF ITS
LIGHTNING...EXCEPT ON THE SOUTHERN MOST STORMS WHICH WILL NOT IMPACT
THE TERMINALS. EXPECT THAT BY THE TIME THE 06Z TAFS GO INTO EFFECT
THIS AREA WILL BE SOUTH OF ORD...AND SHOULD CLEAR MDW BY 0630Z. NEXT
AREA OF CONCERN IS AN AREA OVER NORTHWEST ILLINOIS. IF THIS AREA
HOLDS TOGETHER...EXPECT IT TO BE THROUGH THE CHICAGO TERMINALS BY
AROUND 09Z. GIVEN THE DOWNWARD TRENDS THOUGH DO NOT ANTICIPATE THIS
TO IMPACT BEYOND RFD WHICH SHOULD CLEAR BY 730Z.
TO OUR NORTH...AN OUTFLOW BOUNDARY IS EVIDENT ON RADAR IMAGERY
RACING SOUTH ALONG THE COAST OF LAKE MICHIGAN. THE CONVECTION TO
SUSTAIN THIS PUSH DOWN THE LAKE HAS SHIFTED EAST OF THE
BOUNDARY...WHICH IS STRUGGLING TO PUSH VERY FAR INLAND...BUT THERE
ARE CURRENTLY NORTHEAST GUSTS OF AROUND 20-25 KTS ASSOCIATED WITH
THE BOUNDARY. WINDS ARE EXPECTED TO SHIFT NORTHEAST AND INCREASE
SHARPLY...THEN SHOULD SETTLE DOWN SHORTLY THEREAFTER AND RETURN
CLOCKWISE BACK TO A MORE SOUTHERLY WIND...AND EVENTUALLY
SOUTHWEST. BASED ON THE CURRENT TRAJECTORY...IT WILL BE NEAR
ORD...MDW...AND GYY BY 630Z.
DID NOT MAKE ANY BIG CHANGES BEYOND THE FIRST 6 HOURS OF THE TAF.
FRONTAL TIMING STILL APPEARS TO BE AROUND 14Z WITH WINDS SHIFTING
TO NORTH...THEN NORTHEAST BEHIND THE FRONT. CANT COMPLETELY RULE
OUT ADDITIONAL THUNDERSTORMS DEVELOPING NEARBY TOMORROW AS WE
QUICKLY DEVELOP MODERATE INSTABILITY OVER THE AREA...BUT IT
APPEARS THE BEST FORCING WILL SHIFT SOUTH OF THE TERMINALS. SOME
MODEL SOUNDINGS CONTINUE TO INDICATE THE POTENTIAL FOR MVFR CIGS
TO DEVELOP RIGHT BEHIND THE FRONT FOR A COUPLE HOURS...THOUGH MOS
GUIDANCE INDICATES CONDITIONS WILL REMAIN VFR BEHIND THE FRONT.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM CONFIDENCE THAT TSRA WILL NOT IMPACT THE TERMINALS THE
REMAINDER OF TONIGHT AND TOMORROW.
* MEDIUM CONFIDENCE IN WIND TRENDS WITH A SHIFT TO
NORTHEAST...VEERING BACK TO SOUTHWEST OVERNIGHT. MEDIUM TO HIGH CONFIDENCE
IN FROPA TIMING THURSDAY MORNING.
* LOW CONFIDENCE IN MVFR CIGS BEHIND FRONT.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR. NORTHEAST WINDS.
SATURDAY...VFR. EASTERLY WINDS.
SUNDAY THROUGH TUESDAY...VFR.
RC
&&
.MARINE...
250 AM CDT
LOW PRESSURE OF 29.1 INCHES LIES OVER FAR NORTHERN QUEBEC WITH A
COLD FRONT SAGGING TO THE SOUTHWEST ACROSS THE UPPER PENINSULA OF
MICHIGAN AND INTO CENTRAL WISCONSIN. THIS FRONT WILL CONTINUE TO
MOVE SOUTH ACROSS LAKE MICHIGAN THIS MORNING. THE FRONT SHOULD BE
SOUTH OF LAKE MICHIGAN THIS AFTERNOON AS HIGH PRESSURE OF 30.2
INCHES BUILDS ACROSS THE UPPER MIDWEST. THE HIGH WILL SHIFT EAST
OVER LAKE MICHIGAN ON FRIDAY...THEN OVER THE EASTERN LAKES
SATURDAY. A BROAD AREA OF LOW PRESSURE AVERAGING 29.7 INCHES WILL
DEVELOP OVER THE NORTHERN PLAINS AND CANADIAN PRAIRIES SUNDAY AND
MONDAY...AND SLOWLY SHIFT EAST ACROSS THE GREAT LAKES THROUGH
MIDWEEK.
BMD
&&
.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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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
419 AM EDT THU AUG 22 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 342 AM EDT THU AUG 22 2013
A COLD FRONT WILL TRACK THROUGH CENTRAL INDIANA TODAY AND TONIGHT
AND BRING SCATTERED THUNDERSTORMS TO CENTRAL INDIANA. HIGH PRESSURE
WILL BUILD ACROSS THE GREAT LAKES IN WAKE OF THE FRONTAL
PASSAGE...WITH DRY SEASONABLE CONDITIONS FRIDAY AND SATURDAY. THE
EXPANSION OF A BROAD UPPER RIDGE WILL SIGNAL THE BEGINNING OF A
WARMING TREND ON SUNDAY...WITH HOT WEATHER EXPECTED TO PERSIST FOR
MUCH OF NEXT WEEK.
&&
.NEAR TERM /TODAY/...
ISSUED AT 342 AM EDT THU AUG 22 2013
SCATTERED CONVECTION CONTINUES TO DEVELOP EARLY THIS MORNING AHEAD
OF WEAKENING STORM COMPLEX OVER LOWER MICHIGAN AND NORTHERN INDIANA.
HIGH CLOUDS ASSOCIATED WITH THE STORMS HAVE QUICKLY ENCOMPASSED A
GOOD PORTION OF THE FORECAST AREA ALREADY. TEMPS WERE PREDOMINANTLY
IN THE 60S AS OF 07Z.
BULK OF THE MODEL GUIDANCE LARGELY STRUGGLING WITH CURRENT
CONDITIONS AND SPECIFICALLY WITH THE AFOREMENTIONED COMPLEX TO THE
NORTH. CONVECTION IS WEAKENING AND DIMINISHING IN COVERAGE AS
EXPECTED WITH IT MOVING INTO A LESS FAVORABLE ENVIRONMENT OVER THE
FORECAST AREA. HRRR BEGINNING TO CATCH ON TO THE FASTER ARRIVAL OF
CONVECTION...AND MOST RECENT DATA SUGGESTIVE OF SCATTERED CONVECTION
IN A PROGRESSIVELY WEAKENED STATE MIGRATING INTO NORTHERN COUNTIES
THROUGH DAYBREAK. BEST COVERAGE TO RAINFALL SHOULD IMPACT NORTHEAST
COUNTIES OVER THE NEXT SEVERAL HOURS WITH PRECIP MORE SCATTERED
FURTHER WEST. HAVE BUMPED UP POPS THROUGH MID MORNING OVER THE
NORTHERN HALF OF THE FORECAST AREA FROM PREVIOUS FORECAST AS A
RESULT.
LOWER CONFIDENCE IN POTENTIAL CONVECTIVE COVERAGE AS THE DAY
PROGRESSES. STRONGER FORCING ALOFT MOVING INTO THE EASTERN GREAT
LAKES AND ANTICIPATE MUCH OF THE CONVECTION WILL EVENTUALLY END UP
TO THE EAST OF THE REGION IN CLOSER PROXIMITY TO THE BETTER FORCING.
CONVECTIVE COVERAGE FOR THE AFTERNOON WILL DEPEND ON HOW QUICKLY
CLOUD DEBRIS DIMINISHES AND THE AMOUNT OF INSTABILITY OVER THE
REGION LATER TODAY. MAIN CATALYSTS FOR CONVECTIVE DEVELOPMENT DURING
THE AFTERNOON WILL BE FORCING ASSOCIATED WITH THE FRONT AND
AVAILABLE INSTABILITY. IN ADDITION...SHORTWAVE ALOFT ASSOCIATED WITH
CONVECTIVE COMPLEX CURRENTLY OVER THE MISSOURI VALLEY WILL TRACK
INTO THE REGION BY LATE AFTERNOON AND MAY AID IN ADDITIONAL
CONVECTIVE DEVELOPMENT. WILL CONTINUE WITH 40-50 POPS DURING THE
AFTERNOON.
TEMPS...DESPITE PRESENCE OF ADDITIONAL HIGH CLOUDS THIS MORNING...
RECENT TREND HAS BEEN FOR TEMPS TO MAX OUT NEAR THE HIGH END OF
GUIDANCE AND SEE NO REASON TO DEVIATE FROM PERSISTENCE TODAY EVEN
WITH A GREATER THREAT FOR STORMS. WILL LEAN CLOSE TO MAV GUIDANCE.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
ISSUED AT 342 AM EDT THU AUG 22 2013
FORECAST CHALLENGES FOCUS ON PRECIP CHANCES TONIGHT AND TEMPS
THROUGHOUT THE SHORT TERM.
BULK OF SCATTERED CONVECTION LIKELY TO BE FOCUSED ALONG AND SOUTH OF
I-70 BY THIS EVENING AS THE INCREASINGLY DIFFUSE FRONTAL BOUNDARY
PROGRESSES SOUTH. WILL MAINTAIN HIGHEST POPS OVER SOUTHERN COUNTIES
AND PREDOMINANTLY DURING THE EVENING...WITH PRECIP CHANCES ENDING
FROM THE NORTH AFTER MIDNIGHT AS THE FRONT CONTINUES MOVING SOUTH
INTO THE TENNESSEE VALLEY. HIGH PRESSURE WILL MOVE ACROSS THE
GREAT LAKES LATE TONIGHT WITH DRIER AIR ADVECTING INTO THE REGION
FROM THE NORTH. DEEPER MOISTURE WILL BE PUSHED TO THE SOUTH WITH
PRECIP LIKELY TO BE COMPLETELY OUT OF SOUTHERN COUNTIES BY 12Z
FRIDAY.
THE HIGH WILL TRACK THROUGH THE GREAT LAKES FRIDAY WITH NORTHEAST
WINDS CONTINUING TO BRING DRIER AIR AND SUBSIDENCE ALOFT INTO THE
REGION FROM THE NORTH. PRESENCE OF COLD ADVECTION IN THE WAKE OF THE
FRONTAL BOUNDARY WILL ENABLE SOME CU DEVELOPMENT THROUGH THE
AFTERNOON...ESPECIALLY ACROSS THE SOUTHERN HALF OF THE FORECAST AREA
WHERE LOW LEVEL MOISTURE WILL BE MORE PREVALENT. CU WILL DIMINISH
TOWARDS SUNSET WITH SKIES BECOMING MAINLY CLEAR AS EVEN DRIER AIR
BUILDS IN FROM THE NORTHEAST. DRY AND SEASONABLE CONDITIONS CAN BE
EXPECTED FOR THE REMAINDER OF THE SHORT TERM AS THE HIGH CENTERS
ACROSS NEW ENGLAND AND THE MID ATLANTIC. PREDOMINANT EASTERLY FLOW
WILL CONTINUE TO PUMP DRY AIR INTO CENTRAL INDIANA. MODEL SOUNDINGS
SUGGESTIVE OF MAINLY SUNNY CONDITIONS SATURDAY WITH LITTLE TO NO CU
DEVELOPMENT ANTICIPATED.
TEMPS...LOW LEVEL THERMALS REMAIN SUPPORTIVE OF WARMER MAVMOS
GUIDANCE AND WILL CONTINUE TO TREND HIGH TEMPS TOWARDS THE MAV.
RECENT DRY STRETCH ALSO WOULD SUPPORT WARMER TEMPS WITH HIGHS BOTH
FRIDAY AND SATURDAY EXPECTED TO BE IN THE LOW/MID 80S FOR MUCH OF
THE REGION. POTENTIAL FOR NEAR IDEAL RADIATIONAL COOLING CONDITIONS
BOTH FRIDAY AND SATURDAY NIGHTS WITH MAINLY CLEAR SKIES AND LIGHT
WINDS. SHOULD BE A GOOD SETUP FOR A RURAL-URBAN SPLIT IN TEMPS AS
OUTLYING LOCALES DROP INTO THE 50S.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
ISSUED AT 244 AM EDT THU AUG 22 2013
MODELS ARE CLOSE ENOUGH THAT THE ALLBLEND INITIALIZATION CAN BE USED
FOR MOST FEATURES...UNLESS NOTED BELOW. FOCUS IS MAINLY ON
TEMPERATURES.
A LARGE UPPER HIGH WILL BUILD ACROSS THE CENTRAL USA DURING THE
EXTENDED...AND THIS HIGH WILL BE THE MAIN INFLUENCE ON CENTRAL
INDIANA WEATHER. TEMPERATURES WILL WARM AS THE HIGH BUILDS IN AND
REMAINS IN CONTROL...SO HIGHS WARMING INTO THE 90S LOOK GOOD. BUMPED
UP ALLBLEND A BIT ON SOME DAYS AS IT SEEMED A LITTLE TOO COOL GIVEN
THE EXPECTED CONDITIONS.
REMOVED ALLBLEND/S CHANCES FOR RAIN THROUGH THE PERIOD. AT THE
MOMENT IT LOOKS LIKE ANY RING OF FIRE THUNDERSTORMS SHOULD REMAIN
OFF TO THE NORTH AND EAST...ESPECIALLY GIVEN THAT 700MB TEMPERATURES
WILL EXCEED 10C AND SHOULD CAP THINGS THROUGH THE PERIOD. OF COURSE
CANNOT ABSOLUTELY RULE OUT A POP UP STORM IN THE AFTERNOON...BUT
ODDS ARE TOO LOW TO MENTION AT THIS TIME.
&&
.AVIATION /DISCUSSION FOR THE 22/09Z TAF UPDATE/...
ISSUED AT 419 AM EDT THU AUG 22 2013
CONVECTION IS WORKING ITS WAY SOUTH ACROSS NORTHERN PORTIONS OF
INDIANA AT THE MOMENT. CURRENT TRENDS ARE FOR THE BULK OF THE
RAINFALL TO REMAIN JUST NORTHEAST OF KIND...BUT SCATTERED CONVECTION
WILL STILL BE NEAR KIND BY 10Z. HAVE ADDED VCSH FOR SEVERAL HOURS
THIS MORNING. LIGHTNING IS DECREASING SO LEFT THUNDER OUT FOR NOW.
PREVIOUS DISCUSSION FOLLOWS...
FOG POSSIBLE AGAIN TONIGHT. EXCEPT FOR PERHAPS BMG IFR APPEARS
UNLIKELY...BUT THIS WAS THE CASE LAST NIGHT AND THE OUTLYING SITES
ALL DROPPED BELOW 1SM AT LEAST BRIEFLY. WILL FORECAST MVFR
VISIBILITIES WITH BCFG TO ACCOUNT FOR POSSIBLE BRIEF REDUCTIONS
LOWER THAN PREVAILING MVFR.
VFR WILL RETURN BY MID MORNING.
SCATTERED SHOWERS AND THUNDERSTORMS ARE TRYING TO WORK THEIR WAY
SOUTH THROUGH NORTHERN INDIANA. NOT SURE IF THESE WILL SURVIVE TO
THE TAF SITES...BUT WILL INTRODUCE A VCSH AT KLAF FOR NOW AND
CONTINUE TO MONITOR.
STORMS WILL BE AT LEAST A SMALL POSSIBILITY WITH COLD FRONT
APPROACHING LATER TODAY. PREVIOUS FORECASTS INSERTED PROB30 AND THIS
IS REASONABLE.
WINDS WILL BE 10KT OR BELOW THROUGHOUT THE PERIOD.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....50
AVIATION...NIELD/50
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
WWW.TWITTER.COM/NWSINDIANAPOLIS
WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
342 AM EDT THU AUG 22 2013
.UPDATE...
THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN UPDATED
BELOW.
&&
.SYNOPSIS...
ISSUED AT 342 AM EDT THU AUG 22 2013
A COLD FRONT WILL TRACK THROUGH CENTRAL INDIANA TODAY AND TONIGHT
AND BRING SCATTERED THUNDERSTORMS TO CENTRAL INDIANA. HIGH PRESSURE
WILL BUILD ACROSS THE GREAT LAKES IN WAKE OF THE FRONTAL
PASSAGE...WITH DRY SEASONABLE CONDITIONS FRIDAY AND SATURDAY. THE
EXPANSION OF A BROAD UPPER RIDGE WILL SIGNAL THE BEGINNING OF A
WARMING TREND ON SUNDAY...WITH HOT WEATHER EXPECTED TO PERSIST FOR
MUCH OF NEXT WEEK.
&&
.NEAR TERM /TODAY/...
ISSUED AT 342 AM EDT THU AUG 22 2013
SCATTERED CONVECTION CONTINUES TO DEVELOP EARLY THIS MORNING AHEAD
OF WEAKENING STORM COMPLEX OVER LOWER MICHIGAN AND NORTHERN INDIANA.
HIGH CLOUDS ASSOCIATED WITH THE STORMS HAVE QUICKLY ENCOMPASSED A
GOOD PORTION OF THE FORECAST AREA ALREADY. TEMPS WERE PREDOMINANTLY
IN THE 60S AS OF 07Z.
BULK OF THE MODEL GUIDANCE LARGELY STRUGGLING WITH CURRENT
CONDITIONS AND SPECIFICALLY WITH THE AFOREMENTIONED COMPLEX TO THE
NORTH. CONVECTION IS WEAKENING AND DIMINISHING IN COVERAGE AS
EXPECTED WITH IT MOVING INTO A LESS FAVORABLE ENVIRONMENT OVER THE
FORECAST AREA. HRRR BEGINNING TO CATCH ON TO THE FASTER ARRIVAL OF
CONVECTION...AND MOST RECENT DATA SUGGESTIVE OF SCATTERED CONVECTION
IN A PROGRESSIVELY WEAKENED STATE MIGRATING INTO NORTHERN COUNTIES
THROUGH DAYBREAK. BEST COVERAGE TO RAINFALL SHOULD IMPACT NORTHEAST
COUNTIES OVER THE NEXT SEVERAL HOURS WITH PRECIP MORE SCATTERED
FURTHER WEST. HAVE BUMPED UP POPS THROUGH MID MORNING OVER THE
NORTHERN HALF OF THE FORECAST AREA FROM PREVIOUS FORECAST AS A
RESULT.
LOWER CONFIDENCE IN POTENTIAL CONVECTIVE COVERAGE AS THE DAY
PROGRESSES. STRONGER FORCING ALOFT MOVING INTO THE EASTERN GREAT
LAKES AND ANTICIPATE MUCH OF THE CONVECTION WILL EVENTUALLY END UP
TO THE EAST OF THE REGION IN CLOSER PROXIMITY TO THE BETTER FORCING.
CONVECTIVE COVERAGE FOR THE AFTERNOON WILL DEPEND ON HOW QUICKLY
CLOUD DEBRIS DIMINISHES AND THE AMOUNT OF INSTABILITY OVER THE
REGION LATER TODAY. MAIN CATALYSTS FOR CONVECTIVE DEVELOPMENT DURING
THE AFTERNOON WILL BE FORCING ASSOCIATED WITH THE FRONT AND
AVAILABLE INSTABILITY. IN ADDITION...SHORTWAVE ALOFT ASSOCIATED WITH
CONVECTIVE COMPLEX CURRENTLY OVER THE MISSOURI VALLEY WILL TRACK
INTO THE REGION BY LATE AFTERNOON AND MAY AID IN ADDITIONAL
CONVECTIVE DEVELOPMENT. WILL CONTINUE WITH 40-50 POPS DURING THE
AFTERNOON.
TEMPS...DESPITE PRESENCE OF ADDITIONAL HIGH CLOUDS THIS MORNING...
RECENT TREND HAS BEEN FOR TEMPS TO MAX OUT NEAR THE HIGH END OF
GUIDANCE AND SEE NO REASON TO DEVIATE FROM PERSISTENCE TODAY EVEN
WITH A GREATER THREAT FOR STORMS. WILL LEAN CLOSE TO MAV GUIDANCE.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
ISSUED AT 342 AM EDT THU AUG 22 2013
FORECAST CHALLENGES FOCUS ON PRECIP CHANCES TONIGHT AND TEMPS
THROUGHOUT THE SHORT TERM.
BULK OF SCATTERED CONVECTION LIKELY TO BE FOCUSED ALONG AND SOUTH OF
I-70 BY THIS EVENING AS THE INCREASINGLY DIFFUSE FRONTAL BOUNDARY
PROGRESSES SOUTH. WILL MAINTAIN HIGHEST POPS OVER SOUTHERN COUNTIES
AND PREDOMINANTLY DURING THE EVENING...WITH PRECIP CHANCES ENDING
FROM THE NORTH AFTER MIDNIGHT AS THE FRONT CONTINUES MOVING SOUTH
INTO THE TENNESSEE VALLEY. HIGH PRESSURE WILL MOVE ACROSS THE
GREAT LAKES LATE TONIGHT WITH DRIER AIR ADVECTING INTO THE REGION
FROM THE NORTH. DEEPER MOISTURE WILL BE PUSHED TO THE SOUTH WITH
PRECIP LIKELY TO BE COMPLETELY OUT OF SOUTHERN COUNTIES BY 12Z
FRIDAY.
THE HIGH WILL TRACK THROUGH THE GREAT LAKES FRIDAY WITH NORTHEAST
WINDS CONTINUING TO BRING DRIER AIR AND SUBSIDENCE ALOFT INTO THE
REGION FROM THE NORTH. PRESENCE OF COLD ADVECTION IN THE WAKE OF THE
FRONTAL BOUNDARY WILL ENABLE SOME CU DEVELOPMENT THROUGH THE
AFTERNOON...ESPECIALLY ACROSS THE SOUTHERN HALF OF THE FORECAST AREA
WHERE LOW LEVEL MOISTURE WILL BE MORE PREVALENT. CU WILL DIMINISH
TOWARDS SUNSET WITH SKIES BECOMING MAINLY CLEAR AS EVEN DRIER AIR
BUILDS IN FROM THE NORTHEAST. DRY AND SEASONABLE CONDITIONS CAN BE
EXPECTED FOR THE REMAINDER OF THE SHORT TERM AS THE HIGH CENTERS
ACROSS NEW ENGLAND AND THE MID ATLANTIC. PREDOMINANT EASTERLY FLOW
WILL CONTINUE TO PUMP DRY AIR INTO CENTRAL INDIANA. MODEL SOUNDINGS
SUGGESTIVE OF MAINLY SUNNY CONDITIONS SATURDAY WITH LITTLE TO NO CU
DEVELOPMENT ANTICIPATED.
TEMPS...LOW LEVEL THERMALS REMAIN SUPPORTIVE OF WARMER MAVMOS
GUIDANCE AND WILL CONTINUE TO TREND HIGH TEMPS TOWARDS THE MAV.
RECENT DRY STRETCH ALSO WOULD SUPPORT WARMER TEMPS WITH HIGHS BOTH
FRIDAY AND SATURDAY EXPECTED TO BE IN THE LOW/MID 80S FOR MUCH OF
THE REGION. POTENTIAL FOR NEAR IDEAL RADIATIONAL COOLING CONDITIONS
BOTH FRIDAY AND SATURDAY NIGHTS WITH MAINLY CLEAR SKIES AND LIGHT
WINDS. SHOULD BE A GOOD SETUP FOR A RURAL-URBAN SPLIT IN TEMPS AS
OUTLYING LOCALES DROP INTO THE 50S.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
ISSUED AT 244 AM EDT THU AUG 22 2013
MODELS ARE CLOSE ENOUGH THAT THE ALLBLEND INITIALIZATION CAN BE USED
FOR MOST FEATURES...UNLESS NOTED BELOW. FOCUS IS MAINLY ON
TEMPERATURES.
A LARGE UPPER HIGH WILL BUILD ACROSS THE CENTRAL USA DURING THE
EXTENDED...AND THIS HIGH WILL BE THE MAIN INFLUENCE ON CENTRAL
INDIANA WEATHER. TEMPERATURES WILL WARM AS THE HIGH BUILDS IN AND
REMAINS IN CONTROL...SO HIGHS WARMING INTO THE 90S LOOK GOOD. BUMPED
UP ALLBLEND A BIT ON SOME DAYS AS IT SEEMED A LITTLE TOO COOL GIVEN
THE EXPECTED CONDITIONS.
REMOVED ALLBLEND/S CHANCES FOR RAIN THROUGH THE PERIOD. AT THE
MOMENT IT LOOKS LIKE ANY RING OF FIRE THUNDERSTORMS SHOULD REMAIN
OFF TO THE NORTH AND EAST...ESPECIALLY GIVEN THAT 700MB TEMPERATURES
WILL EXCEED 10C AND SHOULD CAP THINGS THROUGH THE PERIOD. OF COURSE
CANNOT ABSOLUTELY RULE OUT A POP UP STORM IN THE AFTERNOON...BUT
ODDS ARE TOO LOW TO MENTION AT THIS TIME.
&&
.AVIATION /DISCUSSION FOR THE 22/06Z TAFS/...
ISSUED AT 1256 AM EDT THU AUG 22 2013
FOG POSSIBLE AGAIN TONIGHT. EXCEPT FOR PERHAPS BMG IFR APPEARS
UNLIKELY...BUT THIS WAS THE CASE LAST NIGHT AND THE OUTLYING SITES
ALL DROPPED BELOW 1SM AT LEAST BRIEFLY. WILL FORECAST MVFR
VISIBILITIES WITH BCFG TO ACCOUNT FOR POSSIBLE BRIEF REDUCTIONS
LOWER THAN PREVAILING MVFR.
VFR WILL RETURN BY MID MORNING.
SCATTERED SHOWERS AND THUNDERSTORMS ARE TRYING TO WORK THEIR WAY
SOUTH THROUGH NORTHERN INDIANA. NOT SURE IF THESE WILL SURVIVE TO
THE TAF SITES...BUT WILL INTRODUCE A VCSH AT KLAF FOR NOW AND
CONTINUE TO MONITOR.
STORMS WILL BE AT LEAST A SMALL POSSIBILITY WITH COLD FRONT
APPROACHING LATER TODAY. PREVIOUS FORECASTS INSERTED PROB30 AND THIS
IS REASONABLE.
WINDS WILL BE 10KT OR BELOW THROUGHOUT THE PERIOD.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....50
AVIATION...NIELD/50
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
WWW.TWITTER.COM/NWSINDIANAPOLIS
WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1150 PM CDT WED AUG 21 2013
.UPDATE...
ISSUED AT 946 PM CDT WED AUG 21 2013
SURFACE AND 850 MB FRONTS TO PUSH THROUGH MUCH OF THE AREA OVER THE
NEXT 24 HRS. MOISTURE POOLING JUST AHEAD OF THESE BOUNDARIES IN
WEST TO EAST FASHION WITH SFC DEWPTS IN THE 70S AND LAYER PWATS
APPROACHING 2 INCHES. MEANWHILE...DISTURBANCE IN MONSOONAL
MOISTURE EMERGING INTO THE PLAINS FROM ROCKIES AND ON AN EASTERLY
COURSE AROUND PERIPHERY OF SOUTHERN PLAINS HEAT DOME. THESE
INGREDIENTS ARE ENCOURAGING FOR RAIN PROSPECTS NEXT 24 HRS. ALSO
ENCOURAGING TO SEE SOME PCPN ALREADY SNEAKING INTO FAR NORTH AND
EAST PORTIONS OF CWA... AND ANTICIPATE MORE DEVELOPMENT OVERNIGHT
ZIPPERING BACK TOWARD NE CONVECTION SLIDING E-THEN S/E THROUGH
THU AM PER CORFIDI VECTORS. WILL HAVE UPDATED GRIDS/ZFP OUT SOON.
&&
.SYNOPSIS...
ISSUED AT 314 PM CDT WED AUG 21 2013
12Z UA ANALYSIS HAS AN 850MB TROF RUNNING FROM WESTERN LAKE SUPERIOR
INTO WYOMING. AHEAD OF THIS TROF 850MB DEW POINTS WERE IN THE MID
TEENS FROM UPPER MICHIGAN INTO EASTERN NEBRASKA. SATELLITE/RADAR
TRENDS THROUGH MID AFTERNOON SHOW VERY LITTLE IN THE WAY OF DIURNAL
CLOUDS ACROSS THE AREA BUT CONVECTION HAS FIRED ALONG THE COLD FRONT
FROM NEAR KFSD INTO WESTERN WISCONSIN.
18Z SFC ANALYSIS HAS A WEAK LOW NEAR KFSD. THE FRONT RAN NORTHEAST
FROM THE LOW INTO WESTERN UPPER MICHIGAN. AROUND THE FRONTAL
BOUNDARY DEW POINTS WERE IN THE LOW 70S WITH 60S ACROSS THE
REMAINDER OF THE MIDWEST.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 314 PM CDT WED AUG 21 2013
THE CONVECTION THAT HAS DEVELOPED THIS AFTERNOON IS IN AN AREA OF
STEEP 850-700MB LAPSE RATES AND IN THE SLIGHTLY BETTER
FORCING/CONVERGENCE ASSOCIATED WITH THE FRONTAL ZONE. THE RAP TRENDS
KEEP MORE STABLE AIR ACROSS THE IMMEDIATE AREA THROUGH LATE
AFTERNOON SO ANY CONVECTION APPROACHING THE AREA WILL DISSIPATE.
THE MCS AND LIFT TOOLS SUGGEST ISOLATED TO POSSIBLY SCATTERED
CONVECTION ENTERING THE HWY 20 CORRIDOR DURING THE EARLY EVENING. BY
MID TO LATE EVENING NEW CONVECTION SHOULD DEVELOP AND BECOME LOOSELY
ORGANIZED FROM HWY 30 ON NORTH. BOUNDARIES FROM THIS CONVECTION
SHOULD ALLOW ISOLATED SHOWERS AND STORMS TO DEVELOP ALONG AND SOUTH
OF I-80 AFTER MIDNIGHT.
ON THURSDAY...LINGERING NOCTURNAL CONVECTION SHOULD BE OVER THE AREA
AS THE FRONT CONTINUES TO SLOWLY MOVE SOUTH THROUGH THE AREA.
DIFFERENTIAL HEATING WILL THEN ALLOW NEW CONVECTION TO DEVELOP
DURING THE LATE MORNING AND AFTERNOON HOURS. AS THE NEXT CANADIAN
HIGH BUILDS INTO THE GREAT LAKES...THE DRIER AIR WILL SLOWLY FORCE
THE CONVECTION SOUTH THURSDAY AFTERNOON WITH IT ONLY OVER THE
SOUTHWEST THIRD OF THE CWFA BY THURSDAY EVENING. ..08..
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 314 PM CDT WED AUG 21 2013
AN UPPER RIDGE OVER THE WESTERN STATES IS PROGGED TO BUILD EAST AND
STRENGTHEN THROUGH THE MIDDLE OF NEXT WEEK...PROLONGING THE DRY
CONDITIONS AND BRINGING LATE SUMMER HEAT TO THE REGION.
ABOUT THE ONLY CHANCE OF RAIN WILL BE THE POTENTIAL FOR SOME
LINGERING SHRA/TSRA OVER THE SOUTHWEST THURSDAY NIGHT NEAR A
DECAYING FRONT OVER MISSOURI. FORCING WILL NOT BE VERY STRONG GIVEN
THE WEAK FLOW NEAR THE FRONTAL ZONE AND WITH THE UPPER RIDGE
BUILDING INTO THE REGION...POPS WERE KEPT IN THE SLIGHT CHANCE
CATEGORY.
THE UPPER RIDGE CONTINUES TO BUILD INTO THE REGION WITH A
594DM-PLUS H5 HIGH CENTERED OVER MO BY SUNDAY NIGHT AND REMAINING
IN PLACE THROUGH THE MIDDLE OF THE WEEK. THE STRONGER MID LEVEL
FLOW WILL BE DIVERTED AROUND THE RIDGE WHICH WILL KEEP THE BETTER
FORCING WELL NORTH OF THE AREA. THE GFS AND 12Z ECMWF SHOW SOME QPF
OVER THE AREA BY NEXT WEDNESDAY OR WEDNESDAY NIGHT ASSOCIATED WITH
A SHORT WAVE AND FRONT MOVING THE THROUGH THE WESTERN GREAT LAKES
AND MISSISSIPPI VALLEY. HOWEVER KEPT POPS OUT OF THE FORECAST FOR
NOW WITH MID LEVEL TEMPS PROGGED TO BE AROUND 12C SUGGESTING THESE
FEATURES WILL BE FIGHTING A CAP.
SUMMERTIME HEAT WILL BE RETURNING TO THE REGION AS H8 TEMPS WARM
INTO THE LOW 20/S BY SUNDAY AND REMAIN THERE THROUGH MID WEEK. THE
BLENDED GUIDANCE WAS WARMING HIGH TEMPERATURES TO AROUND 90 BUT
MIXING DOWN H8 TEMPS EARLY NEXT WEEK YIELDED HIGHS IN THE LOW TO MID
90S. FORECAST HIGHS WERE SKEWED TOWARD THE TEMPS DERIVED FROM MIXING
WHICH SEEM MORE REASONABLE. WITH THESE WARMER TEMPERATURES...AND
DEWPOINTS EXPECTED TO BE NEAR 70...WE WILL PROBABLY SEE HEAT INDICES
CLOSE TO 100 DURING THE HEAT OF THE DAY. AT THIS TIME IT DOESN/T
APPEAR THAT WE WILL BE CLOSE TO ANY RECORD HIGHS...AT LEAST THROUGH
THE 28TH. RECORDS DURING THIS TIME ARE NEAR OR ABOVE 100 AT THE
CLIMATE SITES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1123 PM CDT WED AUG 21 2013
FRONTAL ZONE TO SAG THROUGH MUCH OF THE AREA NEXT 24 HRS AND WILL
BE ACCOMPANIED BY CHC OF SHOWERS AND STORMS. BEST CHCS STILL
LOOK TO BE NORTH OF I-80 LATE TONIGHT THROUGH MIDDAY THU. MVFR TO
POSSIBLY IFR VSBYS EXIST WITH ANY STORMS. LIGHT WINDS AND
MOISTURE POOLING AHEAD OF FRONT WILL AID IN SOME FOG DEVELOPING
BETWEEN 09Z-14Z WITH VSBYS MAINLY 3-6SM ALTHOUGH CAN/T RULE OUT
IFR VSBYS AT KDBQ WHERE BETTER MOISTURE RESIDES.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...05
SYNOPSIS...08
SHORT TERM...08
LONG TERM...DLF
AVIATION...05
AREA FORECAST DISCUSSION
NWS GOODLAND KS
249 AM MDT THU AUG 22 2013
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 248 AM MDT THU AUG 22 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW BROAD RIDGE STILL IN
PLACE ACROSS THE SOUTHERN PLAINS...WITH ACTIVE ZONAL FLOW ACROSS
THE NORTHERN PLAINS. SEVERAL SHORTWAVE TROUGHS ARE IN PLACE WITHIN
THE MEAN FLOW OVER CENTRAL NEBRASKA AND WESTERN WYOMING. AT THE
SURFACE A COLD FRONT HAS PUSHED SOUTH OVER OUR CWA AND IS
CURRENTLY EXTENDING FRONT NORTON TO CHEYENNE WELLS BEFORE TURNING
BACK TO THE NORTH ALONG THE THE FRONT RANGE IN COLORADO.
THUNDERSTORMS DEVELOPED OVERNIGHT AHEAD OF THIS FRONT IN THE FAR
EASTERN PART OF THE CWA...WITH SUPPORT FROM H85 50KT JET AND
STRONG THETA-E CONVERGENCE IN THE H85-H7 LAYER. SHORT RANGE
GUIDANCE SUPPORTS THIS ACTIVITY PULLING OFF THE EAST THROUGH
SUNRISE...HOWEVER LITTLE WILL CHANGE REGARDING INSTABILITY/FORCING
SO WILL NEED TO MONITOR/REEVALUATE IF I NEED TO KEEP POPS MENTION
BEYOND 15Z FOR THESE LOCATIONS. ADDITIONAL THUNDERSTORM IS
EXPECTED TO DEVELOP THIS AFTERNOON GENERALLY ALONG THE THE STALLED
FRONT...WITH ADDITIONAL FORCING IN THE LATE AFTERNOON THROUGH
EVENING ASSOCIATED WITH SHORTWAVE TROUGH PASSAGE IN NEBRASKA. WITH
FRONT OVER OUR CWA WE SHOULD SEE BETTER COVERAGE ALONG
FRONT. BETTER INSTABILITY GENERALLY TO THE NORTH OF THE FRONT
WHERE TD VALUES IN THE 60S WILL BE...SO I KEPT CHANCE POPS
GENERALLY OVER THE NW CWA. NAM/RAP BOTH SHOW SB/ML CAPE IN EXCESS
OF 2000 J/KG NORTH OF THIS FRONT WHICH COULD CERTAINLY SUPPORT
STRONG UPDRAFTS. SHEER ON THE OTHER HAND IS NOT QUITE AS
STRONG (0-6KM 20-25KT). THERE DOES APPEAR TO BE ENOUGH SUPPORT FOR
AN ELEVATED LARGE HAIL/STRONG WIND THREAT WITH THUNDERSTORMS THAT
DEVELOP.
AFTER TOMORROW NIGHT PRECIP CHANCES DECREASE SIGNIFICANTLY WITH
INCREASING CAP AND STRONGER SUBSIDENCE ASSOCIATED WITH BUILDING
RIDGE. THERE IS SOME INDICATION OF THUNDERSTORMS MOVING INTO THE
FAR NW PART OF THE CWA FRIDAY AFTERNOON/EVENING...SO I ADDED
SLIGHT CHANCE POPS. BY SATURDAY THE MEAN STORM TRACK WILL HAVE
SHIFTED FAR ENOUGH NORTH WITH STRONG CINH AND LARGE SCALE
SUBSIDENCE INHIBITING AFTERNOON/EVENING CHANCES.
TEMPS WILL DROP CLOSER TO SEASONAL NORMS TODAY BEHIND FRONT IN
THE UPPER 80S/LOW 90S. TH TREND WILL BE MUCH ABOVE NORMAL FRIDAY
AND SATURDAY WITH STRONG RIDGE (595DM) AND STRONG WAA ASSOCIATED
WITH SOUTHERLY FLOW EAST OF STRENGTHENING LEE TROUGH. HAVE TRENDED
TEMPS TOWARDS UPPER 90S BASED ON MIXING WED...AND MIGHT BE A FEW
DEGREES TOO COOL WITH TEMPS NEAR 100F NOT OUT OF THE QUESTION.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 248 AM MDT THU AUG 22 2013
FORECAST PATTERN FOR THE WEEKEND AND EARLY NEXT WEEK HAS CHANGED
LITTLE OVER THE PAST FEW DAYS. A STRONG UPPER-LEVEL RIDGE WILL BE
CENTERED OVER THE CENTRAL PLAINS FOR MUCH OF THE PERIOD...WITH THE
GEM AND ECMWF PLACING THE UPPER HIGH JUST EAST OF THE CENTRAL
PLAINS. WHILE THE RIDGE IS IN PLACE PRECIP CHANCES WILL BE NEAR-NIL
AS DISTURBANCES ROTATE AROUND THE RIDGE. TEMPS WILL BE WELL ABOVE
NORMAL WITH 850MB TEMPS IN THE LOW 30S C...TRANSLATING TO HIGHS IN
THE MID TO UPPER 90S. WOULD NOT BE SURPRISED TO SEE SOME SPOTS HIT
THE TRIPLE DIGITS MON OR TUES...THE HEAT PEAKING AROUND TUESDAY
BEFORE THE RIDGE SHIFTS A BIT FURTHER EAST INTO THE MIDDLE OF THE
WEEK. WINDS DURING THE PERIOD WILL BE PRETTY BREEZY OUT OF THE
SOUTH AT 15 TO 20 MPH DURING THE AFTERNOONS AS A NORTH-SOUTH
ORIENTED SURFACE TROUGH DEVELOPS IN EASTERN COLORADO.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1130 PM MDT WED AUG 21 2013
VFR CONDITIONS ARE FORECAST FOR THE 6Z TAFS. CURRENT RADAR SHOWS
THE COLD FRONT MOVING SOUTH THROUGH THE AREA. IF THE FRONT
CONTINUES SOUTH AT ITS PRESENT SPEED...FRONT SHOULD BE THROUGH
BOTH SITES AROUND 7Z. NORTHEAST WINDS MAY GUST TO 20KTS BRIEFLY
BEHIND THE FRONT. AM ANTICIPATING THE FRONT TO CONTINUE TO MOVE
SOUTH THROUGH THE NIGHT INSTEAD OF SLOWING DOWN AS SOME MODELS
SHOW...ALLOWING THE WINDS TO REMAIN FROM THE NORTHEAST THROUGH
MOST OF THE TAF PERIOD. THERE IS A POSSIBILITY OF THUNDERSTORMS
DEVELOPING OVER EAST CENTRAL COLORADO INTO WESTERN KS THURSDAY
AFTERNOON...BUT DO NOT BELIEVE THE COVERAGE WILL BE ENOUGH TO
WARRANT A MENTION IN THE TAF AT THIS TIME.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...JJM
AVIATION...JTL
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
227 AM EDT THU AUG 22 2013
.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL SLIDE EAST INTO THE REGION
TONIGHT AND THURSDAY BEFORE EXITING THURSDAY NIGHT. A STRONG COLD
FRONT WILL SLIDE THROUGH THE REGION ON FRIDAY. HIGH PRESSURE WILL
BUILD IN FROM THE NORTH FRIDAY NIGHT THROUGH THE COMING WEEKEND
WITH DRIER AND COOLER WEATHER.
&&
.NEAR TERM /THROUGH TODAY/...
FORECAST UPDATED FOR POPS AND ADDING PATCHY FOG. GENERAL IDEA WAS
TO DECREASE POPS FOR THE OVRNGT HRS (BASED ON RADAR TRENDS AND
LATEST MODEL GUIDANCE).
PREVIOUS DISCUSSION...
WATER VAPOR IMAGERY SHOWS A STRONG UPPER LOW OVER THE OHIO VALLEY
WITH JET ENERGY NOW BEGINNING TO MOVE UNDER AND UP THE EASTERN
SIDE OF THE TROUGH. THE 12Z NAM SHOWS THAT THE JET AT 300 MB IS
AROUND 6O KTS. THIS JET WILL HELP TO PULL THE TROUGH EASTWARD THIS
EVENING WHILE ALSO HELPING TO AID IN THE CONVECTION THAT HAS BEEN
FIRING OVER THE HIGHER TERRAIN WEST OF THE AREA. AS THIS FEATURE
PULLS EAST...EXPECT THAT THE CONVECTION OVER THE NC PIEDMONT AND
BEGINNING TO DEVELOP OVER THE VA PIEDMONT WILL PULL EAST INTO
EASTERN VIRGINIA AND EVENTUALLY LIFT NE INTO THE LOWER MD EASTERN
SHORE. HAVE BEEN A LITTLE AGGRESSIVE WITH POPS THIS AFTERNOON
SHOWING AN AREA OF LIKELY POPS NEAR PTB/RIC. THESE POPS MAY BE A
TOUCH HIGH...BUT WITH RADAR SHOWING LOTS OF CONVECTION NOT FAR
AWAY AND THE UPPER LOW BEGINNING TO MOVE WILL KEEP THE 60 POPS IN
FOR NOW. AFTER 6Z...THE JET ENERGY AND SHORTWAVE ENERGY WILL BE
NORTH AND EAST OF THE AREA...AND SHOULD BEGIN TO FEEL THE
INFLUENCE OF THE DRY AIR...SHOWING UP ON THE WATER VAPOR NOW OVER
TN. THIS SHOULD HELP TO SHUT DOWN THE CONVECTION SO HAVE TAPERED
POPS OVERNIGHT. FOR LOWS OVERNIGHT...WITH THE SFC NOT CHANGING AIR
MASS AND LOT OF CLOUDS WITH GOOD MOISTURE HAVE LEANED TOWARD THE
WARMER NUMBERS...TRYING TO GET NEAR OR JUST ABOVE LAST NIGHT LOWS.
ON THURSDAY...THE UPPER TROUGH WILL BE OVER THE AREA AND SLIDING
EAST. THE 12Z NAM AND GFS BOTH SHOW MORE SHORTWAVE ENERGY DIVING
DOWN THE BACK SIDE OF THE TROUGH WITH A VERY MOIST LOW LEVEL AIR
MASS STILL IN PLACE...SCATTERED CONVECTION IS STILL POSSIBLE SO
HAVE HELD ON TO SOME AFTERNOON POPS AS THE TROUGH EXITS. FOR
HIGHS...THE GFS HAS BEEN MUCH BETTER TODAY AND THE NAM SEEMS TO
COOL THE ATMOSPHERE A LITTLE TO MUCH SO HAVE LEANED TOWARD THE
GFS/MAV NUMBERS GETTING HIGHS INTO THE U80S-NR 90 DEGREES.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
THE UPPER TROUGH EXITS QUICKLY THURS EVENING...AND THEN A STRONG
COLD FRONT...NOW OVER THE UPPER MIDWEST WILL MOVE THROUGH THE
GREAT LAKES AN INTO THE MID ATLANTIC STATES LATE THURS NIGHT AND
FRIDAY. THE LIFT FIELDS IN THE MODELS ARE NOT ALL THAT IMPRESSIVE
AND THE SFC CONVERGENCE LOOKS A BIT WEAK. BUT WITH THE AMOUNT OF
MOISTURE AROUND...HAVE HELD ON TO SOME LOW CHANCE POPS ALONG THE
FRONT. THE MODELS HAVE SLOWED A TOUCH WITH THE SPEED FOCUSING MORE
OF THE FRONT ON FRIDAY...BUT THEY DO CONTINUE TO PUSH THE FRONT
WELL SOUTH OF THE AREA BY SATURDAY. NORMALLY THE MODELS ARE A BIT
BULLISH THIS TIME OF YR WITH THE FRONTS...BUT THERE IS A VERY
STRONG AREA OF HIGH PRESSURE...ABOUT 1026 MB IN THE NAM...WHICH
SUPPORTS GETTING THE FRONT COMPLETELY SOUTH OF THE AREA. THIS WILL
BRING AN END TO THE SHOWER CHANCES ON FRI NIGHT AND ALLOW FOR A
MUCH COOLER AND DRIER AIR MASS FOR SATURDAY.
FOR TEMPERATURES HAVE LEANED TOWARD THE MAV NUMBERS A LITTLE MORE
ON FRIDAY BASED UPON CURRENT TRENDS AND THE FACT THAT THE AIR MASS
REALLY DOES NOT CHANGE UNTIL THE COLD FRONT PASSES ON FRI EVENING.
BY SATURDAY...WITH DRIER AIR AND COOLER AIR ALOFT SHOULD SEE
COOLER HIGHS IN THE LOW TO MID 80S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
VERY LITTLE CHANGE TO EXTENDED PORTION OF THE FORECAST. A
LARGE-SCALE AREA OF HIGH PRESSURE SETTLES INTO THE MID ATLANTIC
STATES THROUGH THE WEEKEND AND ORIGINATES FROM THE HUDSON BAY AREA
OF CANADA. THIS WILL BRING A MUCH COOLER AND DRIER AIR MASS TO THE
REGION DURING THIS TIME. EXPECT A GRADUAL COOLING TREND THROUGH
SUNDAY NIGHT WITH HIGHS IN THE LOWER 80S (MID TO UPPER 70S IMMEDIATE
COAST) AND LOWS IN THE LOW TO MID 60S (POSSIBLY UPPER 50S IN THE
EASTERN PIEDMONT). CONDITIONS BEGIN TO REBOUND SLIGHTLY ON MONDAY AS
HIGH PRESSURE SHIFTS SOUTHEAST OFF THE CAROLINA COAST. ON
TUESDAY...A LEE TROUGH DEVELOPS AND A BACKDOOR FRONT PASSES OVER NE
COUNTIES (ESPECIALLY THE MD/VA EASTERN SHORE). THE BACKDOOR FRONT
SHOULD ACT AS A CATALYST FOR LONGWAVE TROUGHING TO COMMENCE OVER THE
NE CONUS DURING THE SECOND HALF OF NEXT WEEK. IF THIS TREND
CONTINUES...THEN ANTICIPATE A RETURN TO WARMER TEMPS BUT SHOWERY
CONDITIONS WITH EACH PASSING DAY.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
SCTD SHWRS AND TSTMS CONTINUE OVER EASTERN PORTIONS OF THE AREA IN
ASSOCIATION WITH A WEAK UPR TROF MOVING ACROSS THE AREA. HAVE
ATTEMPTED TO USE CURRENT RADAR TO TIME/PLACE ANY PRECIP IN TAFS.
TROF MOVES ACROSS REGION THROUGH 12Z...WITH CHANCES FOR SHWRS AND
ISOLATED TSTMS PERSISTING. THERE MAY BE SOME ADDITIONAL SHWR/TSTM
ACTIVITY THURSDAY AFTERNOON...BUT HAVE LEFT OUT OF 06Z TAFS
PRIMARILY DUE TO TIMING UNCERTAINTY. HAVE ALSO INSERTED SOME FOG
INTO THE KSBY/KPHF/KRIC TAF...BASED UPON RECENT RAINFALL AND PERSISTENCE.
SCTD SHOWERS/TSTMS WILL REMAIN POSSIBLE THRU EARLY FRI...BEFORE A
COLD FRONT SWEEPS THRU. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT
FOR FRI NGT THRU THE WEEKEND.
&&
.MARINE...
7 PM UPDATE...HAVE MADE SOME UPWARD ADJUSTMENTS TO WINDS/WAVES ON
THE CHESAPEAKE BAY...ESPECIALLY WESTERN SIDE...BASED UPON CURRENT
CONDITIONS AND LATEST HIGH RES MODEL OUTPUT. HRRR SEEMS TO HAVE A
GOOD HANDLE ON VERY SHORT TERM...AND HAVE USED IT AS PRIMARY WIND
GUIDANCE THROUGH 06Z THURSDAY. NO CHGS AFTER 06Z.
AFTERNOON DISCUSSION...LITTLE TO NO CHANGE TO ONGOING MARINE
FORECAST TONIGHT THROUGH MONDAY. WIND DIRECTIONS HAVE RETAINED
MORE OF A SE-S DIRECTION TODAY THAN PREVIOUSLY ANTICIPATED AND
HAVE INCREASED TO AROUND 10 KT. WINDS WILL CONTINUE TO SLOWLY VEER
TO THE S-SW OVERNIGHT AND INCREASE TWD 10-15 KT AS AN APPROACHING
TROUGH FROM THE OHIO VALLEY TIGHTENS THE PRESSURE GRADIENT OVER
THE WATERS. ALSO EXPECT SHOWER AND THUNDERSTORM CHANCES TO
INCREASE OVERNIGHT AS DECENT SHORTWAVE ENERGY/MOISTURE AND A JET
MAX ENHANCE LIFT/RAIN POTENTIAL. SHOWERS LINGER NEAR THE COAST
EARLY THURSDAY MORNING BUT THERE SHOULD BE A BRIEF REPRIEVE DURING
THE MID-LATE MORNING THROUGH EARLY AFTERNOON HOURS BEFORE
THUNDERSTORMS REGENERATE ALONG A COLD FRONT CROSSING THE WATERS
INTO THE EVENING. WINDS WILL BE PRIMARILY FROM THE SW AOB 15 KT ON
THURSDAY...THEN VEER TO THE W BY FRIDAY MORNING. SEAS WILL AVERAGE
2-3 FT AND WAVES ON CHES BAY WILL AVERAGE 1-2 FT.
THE FRONT STALLS ALONG THE CAROLINAS LATE THURSDAY NIGHT INTO AT
LEAST FRIDAY AFTERNOON...PROVIDING ADDITIONAL FOCUS/CHANCES FOR
AFTERNOON SHOWERS/STORMS ON FRIDAY. WINDS WILL START OUT FROM THE W
AND THEN VEER TO THE NW LATE IN THE AFTERNOON AS HIGH PRESSURE FROM
THE GREAT LAKES BEGINS TO SLIDE INTO THE REGION FROM THE NW. SPEEDS
STAY AOB 15 KT. THE FRONT FINALLY GETS PUSHED WELL SOUTH OF THE AREA
FRIDAY NIGHT BY THE LARGE-SCALE HIGH PRESSURE BUILDING INTO THE MID
ATLANTIC STATES THROUGHOUT THE WEEKEND. COOLER AND DRIER AIR WILL
ACCOMPANY THE HIGH AND QUICKLY BRING PRECIPITATION TO AN END FRIDAY
NIGHT. MODEL GUIDANCE WINDS CONTINUE TO KEEP WIND SPEEDS AOB 15 KT
AS THE COOLER AIR MOVES OVER WARMER WATERS FOR FRIDAY NIGHT INTO
SATURDAY. IN FACT...THEY ARE SHOWING AN INCREASE IN WINDS THROUGH
THE DAY ON SATURDAY AS THE COOL AIR FINALLY ARRIVES AND WINDS BECOME
NELY. WILL STILL MONITOR THE POTENTIAL FOR SCA CONDITIONS BUT NONE
ARE ANTICIPATED ATTM. SURFACE HIGH PRESSURE AND NE-E WINDS AOB 15 KT
SETTLE OVER THE WATERS THROUGHOUT THE WEEKEND. HIGH PRESSURE THEN
SLIDES SOUTHEAST OFF THE CAROLINA COAST ON MONDAY...SHIFTING WINDS
FROM E TO SE-S.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ESS
NEAR TERM...ESS/MAS
SHORT TERM...ESS
LONG TERM...BMD
AVIATION...DAP/WRS
MARINE...BMD/WRS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
132 AM EDT THU AUG 22 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 340 PM EDT WED AUG 21 2013
MAIN FOCUS OF THE FORECAST FOR TODAY IS THE DEVELOPING THUNDERSTORMS
ASSOCIATED WITH A COLD FRONT JUST STARTING TO MOVE INTO WESTERN
UPPER MICHIGAN. THE COLD FRONT HAS BEEN MAKING IT/S WAY
ACROSS WESTERN LAKE SUPERIOR AND NORTHWEST WISCONSIN OVER THE
LAST FEW HOURS AND THERE WAS SOME CONCERN THAT THE STRATUS DECK
THAT DEVELOPED FROM THE FOG NEAR DULUTH WOULD LIMIT COME OF THE
CONVECTION. BUT THE FORCING FROM THE COLD FRONT COMBINED WITH
DIURNAL HEATING HAS BEGAN TO PRODUCE THUNDERSTORMS ALONG THE COLD
FRONT WITH SOME BECOMING FAIRLY STRONG AT THIS WRITTING. WITH A
VERY UNSTABLE ATMOSPHERE (MLCAPE VALUES ANALYZED FROM 2000-3000
J/KG DUE TO SFC DEWPOINTS IN THE UPPER 60S AND LOWER 70S)...THEY
SHOULDN/T HAVE MUCH DIFFICULTY CONTINUING THROUGH THE EARLY EVENING.
AS HAS BEEN MENTIONED OVER THE LAST COUPLE OF DAYS...0-6KM SHEAR
VALUES ARE A LITTLE MARGINAL...BUT LATEST RAP TRENDS SHOW VALUES
APPROACHING 30-35KTS RIGHT ALONG THE COLD FRONT. THIS SHOULD HELP
THE THUNDERSTORMS BECOME A LITTLE MORE TILTED AND BETTER ORGANIZED
OVER THE NEXT FEW HOURS. THINKING THAT THERE IS A DECENT CHANCE OF
THIS CONVECTION BECOMING LINEAR AND MOVING ACROSS MUCH OF UPPER
MICHIGAN LATE THIS AFTERNOON AND INTO THE EVENING. DAMAGING WIND IS
A DECENT THREAT WITH DCAPE VALUES AHEAD OF THE FRONT OF 800-1100
J/KG. WHERE THERE ARE STRONGER STORMS...HAIL IS ALSO A THREAT...BUT
IT WILL LIKELY BE MORE ISOLATED DUE TO THE HIGHER FREEZING LEVELS.
WITH THE BOUNDARIES OVER THE WEST AND LOWER LCL HEIGHTS FROM THE
LEFT OVER STRATUS...THERE COULD BE A ISOLATED TORNADO THREAT...BUT
SHOULD BE CONFINED TO THE LATE AFTERNOON. IN ADDITION...ANOTHER
BOUNDARY (AIDED BY EARLIER CLOUDS/SHOWERS THAT MOVED ACROSS NORTHERN
LAKE SUPERIOR) HAS SETUP FROM WEST TO EAST FROM ONTONAGON THROUGH
MARQUETTE COUNTY. SHOWERS/THUNDERSTORMS HAVE ALSO STARTED TO DEVELOP
ALONG THIS AND ARE SLIDING EAST. SPC HAS JUST ISSUED A SEVERE
THUNDERSTORM WATCH FOR MUCH OF UPPER MICHIGAN THROUGH 4Z. THE COLD
FRONT AND THUNDERSTORMS ARE EXPECTED TO EXIT INTO LAKE MICHIGAN
AROUND 06Z. PREVIOUS FORECAST HAD A GOOD HANDLE ON TIMING...SO ONLY
MADE MINOR ADJUSTMENTS.
THE REST OF THE NIGHT SHOULD BE DRY (DUE TO DRIER AIR SURGING IN
BEHIND THE COLD FRONT)...EVENTHOUGH A FAIRLY POTENT SHORTWAVE WILL
BE SLIDING SOUTHEAST ACROSS THE AREA FROM LAKE WINNIPEG. THIS
SHOULD LEAD TO MOSTLY CLEAR SKIES AND MUCH COOLER TEMPERATURES THAN
LAST NIGHT.
COOLER NORTHERLY FLOW WILL BE IN STORE FOR UPPER MICHIGAN ON
THURSDAY...AS HIGH PRESSURE APPROACHES THE AREA FROM THE UPPER
MISSISSIPPI VALLEY. 850MB TEMPS WILL BE AROUND 10C COOLER THAN
TODAY AND EXPECT A SIMILAR RESPONSE WITH THE HIGHS (IN THE 70S).
COOLEST TEMPERATURES WILL BE NEAR LAKE SUPERIOR...WHERE THE
NORTHERLY WINDS OFF THE LAKE WILL KEEP TEMPS RIGHT AROUND 70. A
SUNNY TO MOSTLY SUNNY SKY IS EXPECTED.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 340 PM EDT WED AUG 21 2013
NAM SHOWS A 500 MB RIDGE ACROSS THE ROCKIES AND CENTRAL PLAINS WITH
A TROUGH OVER THE ERN U.S. 00Z FRI. THE 500 MB RIDGE BUILDS INTO THE
CENTRAL PLAINS THIS FORECAST PERIOD WITH THE EDGE OF THE WESTERLIES
OVER THE AREA THIS FORECAST PERIOD. DID PUT IN SLIGHT CHANCE TO
CHANCE POPS IN THE FORECAST FOR THE WEST HALF FOR SAT AFTERNOON AS A
WARM FRONT HEADS TOWARDS THE AREA AND MOISTURE STARTS TO INCREASE.
OTHERWISE...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST FOR
TEMPERATURES. LOOKS TO STAY WARM THROUGH THIS PERIOD.
IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB RIDGE OVER THE CENTRAL
U.S. SAT NIGHT INTO SUN. THE RIDGE REMAINS STATIONARY THROUGH THE
PERIOD WITH THE U.P. IN THE PERIPHERY OF THE RIDGE IN THE RING OF
FIRE SCENARIO WHERE ANY SHORTWAVE CAN SET OFF A ROUND OF
THUNDERSTORMS. WILL BE HARD TO TIME THESE SHORTWAVES AND EASIEST WAY
TO FORECAST THIS WOULD BE TO BROADBRUSH THIS FORECAST PERIOD WITH
CHANCE POPS EVEN THOUGH IT WILL NOT BE A TOTAL WASHOUT. TEMPERATURES
WILL STAY ABOVE NORMAL FOR THIS FORECAST PERIOD ALONG WITH
INCREASING HUMIDITY. ONLY PERIOD THAT LOOKS DRY IS WED WITH A FRONT
MOVING OUT OF THE AREA.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 131 AM EDT THU AUG 22 2013
BEHIND A COLD FRONT THAT HAS MOVED THROUGH THE AREA...
VFR CONDITIONS WILL PREVAIL THROUGH THE REST OF TONIGHT AND THURSDAY
AS HIGH PRESSURE BUILDS OVER THE AREA. THE EXCEPTION IS THAT SOME FOG
WILL BE PRESENT AT IWD AND SAW UNTIL THIS MORNING.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 340 PM EDT WED AUG 21 2013
A COLD FRONT CURRENTLY MOVING ACROSS CENTRAL LAKE SUPERIOR WILL
CONTINUE SOUTHEAST THIS EVENING AND LEAD TO NORTHERLY FLOW
(GENERALLY BELOW 15KTS) OVER THE LAKE FOR THE REST OF TONIGHT AND
INTO THURSDAY EVENING. HIGH PRESSURE THAT IS PRODUCING THE LIGHTER
WINDS WILL THEN SHIFT SOUTHEAST INTO THE LOWER GREAT LAKES AND
ALLOW WINDS TO SLOWLY INCREASE FROM THE SOUTH-SOUTHWEST FRIDAY INTO
THE WEEKEND. AT THIS POINT...WOULD EXPECT LAKE STABILITY FACTORS TO
KEEP WINDS AT OR BELOW 20KTS.
ONE FINAL ITEM TO MENTION IS IF THE SHOWERS/THUNDERSTORMS AFFECT
ENOUGH OF EASTERN LAKE SUPERIOR TO DEVELOP FOG. LEFT OUT AT THIS
POINT SINCE VISIBLE SATELLITE INDICATED THE FOG OVER NORTHERN LAKE
SUPERIOR HAS DISSIPATED AND THERE IS SOME UNCERTAINTY ON HOW FAR
THE RAIN WILL GET INTO EASTERN LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...07
AVIATION...JLB
MARINE...SRF
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1203 AM EDT THU AUG 22 2013
.AVIATION...
//DISCUSSION...
CLOUDS CONTINUE TO THICKEN AND CIGS LOWER AHEAD OF AN APPROACHING
COLD FRONT OVERNIGHT. AN AREA OF SHOWERS AND THUNDERSTORMS CONTINUES
TO SLOWLY MARCH EAST...HOWEVER AS EVIDENCED BY RADAR THEY ARE HAVING
ISSUES MAINTAINING THEMSELVES AS THEY ENTER SOUTHEAST MICHIGAN. THE
GREATEST THREAT FOR THUNDERSTORMS CONTINUES TO BE THE NORTHERN
AIRPORTS...WITH MODELS CONTINUING TO INDICATE THIS ACTIVITY WILL
DROP OFF AS IT APPROACHES THE METRO AIRPORTS. THEREFORE WILL
CONTINUE THE PREVIOUS FORECAST OF NO THUNDER AT THE METRO AIRPORTS.
CIGS WITH THIS FRONT ARE EXPECTED TO BE AROUND 5KFT...HOWEVER VSBYS
COULD DROP TO MVFR IN RAIN SHOWERS AND THUNDERSTORMS. WINDS SHIFT TO
THE NORTH THURSDAY WITH PLENTY OF DRY AIR RETURNING THINGS TO VFR
AFTER THE RAIN.
FOR DTW...BEST THUNDERSTORM CHARACTERISTICS APPEAR TO BE FURTHER
NORTH...SO WILL CONTINUE TO LEAVE TS OUT OF THE TAFS THIS PERIOD.
WILL UPDATE WITH AMD IF NEEDED...BUT DTW WILL LIKELY DROP TO 4SM
WITH STRONGEST SHOWERS.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE OF CEILINGS BELOW 5000 FEET AFTER 10Z TONIGHT.
&&
.PREV DISCUSSION...ISSUED 339 PM EDT WED AUG 21 2013
SHORT TERM...TONIGHT
VIS SATELLITE AND RADAR SHOW VERY SMALL AREAS OF SHOWERS ALONG AN
AREA OF MOISTURE CONVERGENCE FROM JYM TO PTK. THIS WAS DEPICTED WELL
WITH THE HRRR AS A DIURNAL CONVECTIVE SHOWER EVENT THAT WILL SWING
EAST AND SOUTH...DYING WITH THE LOSS OF DAYTIME HEATING. 20-30 POP
GRIDS WERE UPDATED EARLIER TO INCLUDE THIS CHANCE...WHICH WILL END
NLT 00Z.
CLOUDS AND PRECIP CHANCES INCREASE FROM NW TO SE TONIGHT AS A COLD
FRONT APPROACHES FROM THE NORTHWEST. THERE WILL BE SOME ELEVATED
INSTABILITY...ESPECIALLY NORTH OF I-69 OVERNIGHT AS LI/S ARE -2 OR
-3 AND ABOUT 1000 J/KG OF CAPE IS PRESENT ABOVE 800 MB. WINDS WILL
ALSO VEER AND INCREASE WITH HEIGHT IN THE ELEVATED LAYER
OVERNIGHT...LEADING TO HIGHER POPS TO INCLUDE THUNDER IN THE
FORECAST. THESE CONDITIONS WILL SWING SOUTHEASTWARD THROUGH THE
STATE...BUT HIGHER PW/S (2.0 INCHES) AND LESS INSTABILITY BRING THE
FORECAST TO LOWER THUNDER CHANCES SOUTH OF M-59.
LONG TERM...THURSDAY THROUGH TUESDAY
A WELL-DEFINED 110KT JET IS EVIDENT ALONG THE US/CANADA BORDER THIS
AFTERNOON AS THE UPPER GRADIENT TIGHTENS BETWEEN THE EXPANSIVE
WESTERN U.S. RIDGE AND SHORTWAVE ENERGY DIGGING INTO SOUTHEAST
SASKATCHEWAN AND SOUTHWEST MANITOBA. MESOANALYSIS REVEALS AN
ORGANIZING LOW-LEVEL BAROCLINIC ZONE ASSOCIATED WITH THIS JET THAT
IS BEGINNING TO FEEL ITS WAY SOUTHEAST AS THE LARGE SCALE TROUGH
OVER CENTRAL AND EASTERN CANADA BEGINS TO SWEEP ACROSS THE GREAT
LAKES. RELATIVELY LITTLE HAS CHANGED WITH REGARD TO FORECAST
REASONING. INITIALLY, SOME REMNANT SHOWERS WILL BE POSSIBLE IN
ADVANCE OF THE FRONT IN ASSOCIATION WITH ANY UPSTREAM DEVELOPMENT
OVER WISCONSIN THIS EVENING, ALTHOUGH CONFIDENCE IS NOT PARTICULARLY
HIGH IN THE DEGREE OF COVERAGE EARLY IN THE PERIOD GIVEN THE LACK OF
LARGE SCALE SUPPORT. STILL, EITHER WEAKLY ORGANIZED RIGHT ENTRANCE
SUPPORT, A CONVECTIVELY ENHANCED WAVE EMANATING OUT OF UPSTREAM
ACTIVITY, OR A COMBINATION OF BOTH, STILL WARRANT A CONTINUATION OF
LIKELY POPS ACROSS MUCH OF THE AREA DURING THE FIRST HALF OF THE
DAY.
UNCERTAINTY FURTHER INCREASES FOR THURSDAY AFTERNOON AS BOUNDARY
LAYER RECOVERY WILL BE STRONGLY DEPENDENT ON CLOUD COVER AND
DURATION OF MORNING SHOWERS. THE NAM/GFS REPRESENT THE AGGRESSIVE
SIDE OF THE ENVELOPE WITH UP TO 3000 J/KG SBCAPE DEVELOPING BY MID
AFTERNOON WHEREAS THE GENERAL CONSENSUS OF BOTH HIGHER RESOLUTION
GUIDANCE SUCH AS THE NMM/ARW AS WELL AS THE GEM/ECMWF ALLOW HIGH
PRESSURE TO AGGRESSIVELY BUILD IN WITH LITTLE MORE THAN A LOW
COVERAGE OF AFTERNOON SHOWERS TO SHOW FOR THE FROPA. GIVEN THE
DEGREE OF UNCERTAINTY, FELT IT PRUDENT TO TAPER POPS BACK INTO THE
HIGH CHANCE CATEGORY ESSENTIALLY EVERYWHERE ALONG/NORTH OF I-94,
WHICH REFLECTS THE LATEST FORECAST REASONING BUT STILL LEAVES ROOM
FOR ADJUSTMENT IN EITHER DIRECTION AS NEW DATA BECOMES AVAILABLE.
FOR FAR SOUTHERN AREAS, ENOUGH RECOVERY WILL BE POSSIBLE TO SUPPORT
A PULSE SEVERE THREAT IMMEDIATELY AHEAD OF THE FRONT, BUT WITH THE
BETTER SHEAR LAGGING BEHIND, THE THREAT FOR ORGANIZED SEVERE WEATHER
REMAINS LOW. TEMPERATURES WILL FALL BACK TO NEAR 80 FOR THE WEEKEND
AS COOLER AND DRIER AIR FILTERS INTO SOUTHEAST MI IN THE WAKE OF THE
FRONT AND HIGH PRESSURE SETTLES OVER THE NORTHEASTERN UNITED STATES.
THERE WILL BE NUMEROUS CHANCES FOR THUNDERSTORMS NEXT WEEK AS THE
CWA WILL BE POSITIONED ALONG THE NE PERIPHERY OF THE BUILDING 595DM
RIDGE OVER THE CENTRAL U.S. WHILE REMAINING IN CLOSE PROXIMITY TO
PREVAILING WESTERLY FLOW. THIS WILL SET THE STAGE FOR MULTIPLE
CONVECTIVE COMPLEXES TO AFFECT SOME OR ALL OF THE REGION. INITIAL
EXPECTATIONS ARE THEREFORE FOR THUNDERSTORM ACTIVITY IN THE VICINITY
TO HELP KEEP TEMPERATURES IN CHECK, BUT WITH H5 HEIGHTS IN THE
585-588DM RANGE AND H85 TEMPS NEAR 20C, THE POTENTIAL FOR HIGHS TO
REACH INTO THE 90S WILL EXIST ON BASICALLY ANY DAY FROM MONDAY
ONWARD.
MARINE...
A PRESSURE GRADIENT BETWEEN HIGH PRESSURE IN THE MID-ATLANTIC AND
LOW PRESSURE OVER HUDSON BAY WILL PROVIDE INCREASED SW WINDS
TONIGHT. AIR TEMPERATURES WILL STAY PRETTY WARM UNTIL THE COLD FRONT
SWINGS THROUGH EARLY THURSDAY...SO THERE IS NOT MUCH INSTABILITY
OVER THE LAKES UNTIL THEN. OFFSHORE WINDS WILL BECOME MORE ONSHORE
LATE THURSDAY AND WILL HELP INCREASE WAVE HEIGHTS ALONG THE THUMB`S
SHORE TO 3 FEET. WILL WATCH FOR SMALLCRAFT CONDITIONS NEXT FORECAST
PERIOD...BUT IN THE MEANTIME SIG/MAX WAVES SHOULD STAY MANAGEABLE.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....DG
SHORT TERM...MM
LONG TERM....JVC
MARINE.......MM
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
410 AM CDT THU AUG 22 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 410 AM CDT THU AUG 22 2013
SHORT TERM TRENDS POINT TO SOME ISOLATED THUNDER LIFTING AS FAR
NORTH AS DECAYING FRONTAL BOUNDARY...WITHIN INSTABILITY AXIS AND
NORTHERN PERIPHERY OF COMPLEX OVER IOWA. WILL HAVE TO INCLUDE THIS
FOR MUCH OF THE MORNING HOURS ANYWAY.
THIS CONVECTION IS BEING FORCED BY SOME WEAK LAYERED FRONTOGENESIS.
THIS IS PROGGED BE THE HRRR AND MEMBER 1 AND 2 OF THE HOPWRF TO
GRADUALLY WEAKEN AND DROP FARTHER SOUTH AS DRIER AIR TRIES TO DROP
SOUTHWEST ERODING THE BOUNDARY. SHOULD SEE GRADUAL DRYING THEN INTO
THE AFTERNOON...AS SURFACE HIGH DROPS SOUTHEAST INTO TONIGHT.
CLOUDS SHOULD GIVE WAY TO CLEARING DURING THE DAY...AND CONTINUE
THIS TREND THROUGH THE NIGHT. TEMPERATURES COOL A BIT TO THE LOWER
AND MIDDLE 80S OVER MOST OF THE AREA TODAY. LOWS SHOULD COOL TO
AROUND 50 EAST AND AROUND 60 TO THE SOUTHWEST TONIGHT...AS DRIER AIR
MOVES ACROSS.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 410 AM CDT THU AUG 22 2013
THE MAIN WEATHER HEADLINE IN THE LONG TERM PORTION OF THE FORECAST
WILL BE BUILDING HEAT...AS MID LEVEL HEIGHTS GRADUALLY RISE IN
CONJUNCTION WITH THE EXTENSIVE RIDGE OVER THE CENTRAL CONUS. THE RETURN
OF THE HOT WEATHER WILL BE MET WITH THE ARRIVAL OF A WARM FRONT.
HAVE RETAINED 20-40 POPS FOR FRIDAY NIGHT INTO SATURDAY MORNING AS
THE AFOREMENTIONED FRONT BEGINS TO LIFT ACROSS THE AREA. ALTHOUGH
THE ORIENTATION OF THE 35-40KT PROGGED LLJ IS NOT IDEAL FOR
WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY...INDICATIONS ARE THAT
IT SHOULD BE ADEQUATE FROM CENTRAL MN INTO WEST CENTRAL WI TO
WARRANT LOW CHANCE POPS CENTERED BETWEEN 06Z AND 18Z SATURDAY.
AFTER THAT...OTHER THAN A FEW STRAY SHOWERS/TS NORTH OF INTERSTATE
94 CLOSER TO THE BOUNDARY...MOSTLY DRY CONDITIONS ARE EXPECTED
THROUGH MONDAY AS THE WARM FRONT LIFTS INTO NORTHERN MN. AS THIS
OCCURS...TEMPERATURES WILL MODERATE INTO THE LOW/MID 90S FOR
SUNDAY THROUGH TUESDAY AS DEWPOINTS CREEP TO AROUND 70 DEGREES.
THIS COULD MEAN A PROLONGED PERIOD WITH A HEAT ADVISORY...WITH MAX
HEAT INDICES NEARING 100 DEGREES AND OVERNIGHT LOW TEMPS REMAINING
ELEVATED IN THE LOW/MID 70S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1056 PM CDT WED AUG 21 2013
CDFNT GRADUALLY PROGRESSING SEWD THRU THE AREA...IDENTIFIABLE BY
WINDS SHIFTING TO PREDOMINANTLY NW ALTHOUGH SPEEDS ARE DROPPING TO
5 KT OR LESS. MOST SITES NOW LOOK TO REMAIN VFR THRU THIS PERIOD.
MAINLY HIGH CLOUDS EXPECTED AT KAXN-KSTC...WITH SOME ADDITIONAL
MIDLVL CLOUDS TMRW AFTN AT KMSP-KRNH. THE MAIN CONCERNS THIS
PERIOD ARE AT KEAU AND KRWF THRU DAYBREAK. FOR KEAU...FLIGHT CONDS
HAVE ALREADY DROPPED TO LIFR DUE TO LOW CIGS...BUT THE THREAT OF
IFR/LIFR CIGS CONDS REMAIN THRU DAYBREAK AS THAT AREA RECEIVED
PLENTY OF RAIN THIS EVE...RESULTING IN PLENTY OF LOW LEVEL
MOISTURE AVAILABLE FOR LOW CIGS /IF WINDS DO NOT GO CALM/ OR FOG
/IF WINDS GO CALM/. EITHER WAY...AM ANTICIPATING AT LEAST TEMPO
PERIODS OF IFR/LIFR THRU DAYBREAK THEN VFR AFTERWARDS. FOR
KRWF...THERE ARE COMPETING SHORT-RANGE MODEL IDEAS THAT
SHWRS/TSTMS OVER NE NEBRASKA MAY SLIDE ENE ALONG THE FNT AND MOVE
INTO SW MN. CHCS ON THIS IDEA ARE LOW...AND HOURLY MODEL
INITIALIZATIONS DO NOT LINE UP FAVORABLY...SO HAVE KEPT KRWF DRY
BUT DID ADD IN A MIDLVL CIG OVERNIGHT. ALL SITES THEN GO VFR TMRW
AFTN ONWARD WITH NE WINDS IN THE 5-10 KT RANGE BEFORE DROPPING OFF
TMRW EVE.
KMSP...VFR THROUGHOUT WITH NO PRECIP EXPECTED. MAINLY HIGH CLOUDS
WITH OCNL CIGS AT TIMES...AND SOME PASSING MIDLVL CU CLOUDS. NO
CIGS EXPECTED TMRW AFTN ON THRU THE REST OF THE PERIOD. NE WINDS
THROUGHOUT...APPROACHING 10 KT TMRW AFTN...THEN DROPPING TO
LGT/VRBL TMRW EVE.
/OUTLOOK FOR KMSP/
FRI...VFR. SCHC OF SHRA/TSRA. SE WIND 5 TO 10 KTS.
SAT...OCNL MVFR-MAINLY VFR CIGS. CHANCE TSRA/SHRA. S WIND 10-18 KTS.
SUN...VFR. SW WIND 10-18 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...DWE
LONG TERM...LS
AVIATION...JPC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
229 AM EDT THU AUG 22 2013
.SYNOPSIS...
A PRE-FRONTAL TROUGH WILL BE OVER THE REGION TODAY INTO EARLY
FRIDAY. A COLD FRONT WILL PUSH SOUTH THROUGH NORTH CAROLINA FRIDAY
NIGHT AND EARLY SATURDAY BRINGING COOLER AND DRIER AIR.
&&
.NEAR TERM /TONIGHT/...
AS OF 930 PM WEDNESDAY...
AFTER QUITE A WET LATE AFTERNOON THROUGH EARLY EVENING ESPECIALLY IN
THE SOUTHEAST CWA... THE REMAINDER OF THE NIGHT SHOULD TREND MUCH
DRIER FOR MOST OF CENTRAL NC. AN AREA OF STRATIFORM RAIN COVERS MUCH
OF THE COASTAL PLAIN... IN THE WAKE OF THE DISORGANIZED BAND OF
STORMS NOW MOVING INTO COASTAL NC. MOST CONVECTION-ALLOWING MODELS
AGREE ON NO SIGNIFICANT ADDITIONAL DEVELOPMENT OVERNIGHT... BUT ONE
EXCEPTION IS THE HRRR WHICH SUGGESTS THAT THE BAND OF CONVECTION NOW
EXTENDING FROM CENTRAL WV INTO SW VA/FAR NW NC (ASSOCIATED WITH DPVA
WITHIN THE MID LEVEL TROUGH) WILL PROGRESS EASTWARD OVER THE NEXT
SEVERAL HOURS... BRUSHING ACROSS THE NRN COUNTIES OF CENTRAL NC.
DEEP LAYER BULK SHEAR WILL REMAIN MARGINAL AT AROUND 25 KTS... BUT
THE RAP INDICATES ELEVATED INSTABILITY (MLCAPE OVER 1000 J/KG)
HOLDING THROUGH THE NIGHT. WITH ABOUT 30 METERS OF HEIGHT FALLS
ANTICIPATED OVERNIGHT IN NRN NC WITH THE TROUGH SHIFTING SLOWLY
EASTWARD JUST TO OUR NW... THIS MAY PROVIDE ENOUGH IMPETUS FOR THESE
STORMS TO HOLD TOGETHER AS THEY PUSH EASTWARD. ONCE THE
POST-CONVECTION RAIN CLEARS OUT OF THE EAST IN THE NEXT HOUR OR
SO... WILL RETAIN AN ISOLATED STORM MENTION OVERNIGHT EVERYWHERE
EXCEPT FOR SCATTERED COVERAGE ACROSS THE NORTH. TEMPS ARE ALREADY
VERY CLOSE TO THEIR ANTICIPATED OVERNIGHT LOWS... SO EXPECT READINGS
TO DIP JUST ANOTHER CATEGORY OR SO OVERNIGHT... RESULTING IN LOWS
69-73. -GIH
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
AS OF 310 PM WEDNESDAY...
THURSDAY AND THURSDAY NIGHT:
MEAN FLOW WILL BECOME WESTERLY IN THE WAKE OF THE MID/UPPER TROUGH
EXITING THE AREA BETWEEN 12 TO 18Z...FINALLY DRYING OUT THE
THE ABNORMALLY MOIST(PWATS 1.75-2.00 INCHES)AIRMASS THAT HAS BEEN IN
PLACE OVER THE PAST SEVERAL DAYS. THIS DRYING ALONG WITH STRONG
SYNOPTIC SCALE SUBSIDENCE IN THE WAKE OF THE EXITING TROUGH WILL
LIKELY GO A LONG WAYS IN COUNTERACTING AFTERNOON HEATING AND
RESULTANT DESTABILIZATION TO KEEP CONVECTION AT A MINIMUM THURSDAY
AFTERNOON...ESPECIALLY WEST OF US 1. CONVECTIVE ALLOWING MODELS
STRONGLY SUPPORT THE ABOVE RATIONALE...AND AS SUCH HAVE OPTED TO
CUT POPS A BIT WITH SLIGHT/ISOLATED CHANCE IN THE WEST TO SMALL
CHANCE IN THE EAST. DRY THURSDAY NIGHT UNTIL THE ARRIVAL OF THE
COLD FRONT ON FRIDAY.
FULL SUN THICKNESSES WILL FINALLY BE REALIZED ALLOWING NEAR NORMAL
HIGHS IN THE UPPER 80S TO AROUND 90. LOWS THURSDAY NIGHT IN THE
UPPER 60S TO LOWER 70S.
FRIDAY:
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE ON FRIDAY AS
A COLD FRONT MOVES THROUGH THE AREA AND MOISTURE REMAINS
SUFFICIENTLY HIGH (PWAT VALUES 1.75-2 INCHES). MODELS INDICATE
MODERATE INSTABILITY DEVELOPING DURING THE DAY ON FRIDAY...HOWEVER
GIVEN THAT THE STRONGER SHORT WAVE TROUGH WILL HAVE MOVED EAST OF
THE REGION BY FRIDAY MORNING...WEAK SHEAR (GENERALLY LESS THAN 20
KNOTS) IS PROGGED TO BE OVER THE REGION AND SHOULD THEREFORE LIMIT
ANY STORM ORGANIZATION. HIGHS WILL LIKELY BE IN THE MID/UPPER 80S TO
NEAR 90 DEGREES.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
AS OF 225 AM THURSDAY...
FRIDAY NIGHT AND SATURDAY:
THE SURFACE COLD FRONT MENTIONED ABOVE IN THE SHORT TERM IS EXPECTED
TO MOVE INTO THE AREA LATE FRIDAY EVENING INTO EARLY SATURDAY
MORNING AND BE NEAR THE NC/SC BORDER ACROSS THE CENTRAL PART OF THE
STATE... EXTENDING BACK EAST-NORTHEASTWARD INTO THE COASTAL PLAIN AT
AROUND 12Z SATURDAY. THE FRONTAL IS EXPECTED TO STALL BRIEFLY
THERE... UNTIL THE FINAL MID LEVEL S/W MOVES THROUGH THE AREA
SATURDAY AFTERNOON. THUS... WILL CONTINUE SOLID CHANCES FOR SHOWERS
AND STORMS ALONG AND AHEAD OF THE FRONT FRIDAY EVENING INTO EARLY
SATURDAY MORNING... ENDING FROM NORTH/NORTHWEST TO SOUTH/SOUTHEAST.
WILL CONTINUE TO ADVERTISE A SLIGHT CHANCE OF SHOWERS AND STORMS FOR
SATURDAY MORNING INTO THE AFTERNOON... UNTIL THE FINAL S/W TROUGH
MOVES THROUGH THE AREA THEN (HELPING TO PUSH THE FRONT FURTHER SOUTH
AND USHER IN DRIER AIR). LOWS SATURDAY MORNING WILL GREATLY DEPEND
ON THE TIMING OF THE FRONT AND RESULTANT ADVECTION OF DRIER AIR INTO
THE REGION. THUS... FOR NOW WILL GO WITH MID 60S NORTH TO LOWER 70S
SOUTH. HIGHS SATURDAY 83-86... WITH THE POSSIBILITY FOR HIGH TEMPS
EVEN A BIT LOWER THAN ADVERTISED.
SATURDAY NIGHT THROUGH WEDNESDAY:
SURFACE HIGH PRESSURE WILL BUILD INTO THE AREA AND SETTLE ACROSS THE
REGION FROM SATURDAY NIGHT THROUGH AT LEAST MONDAY. MEANWHILE A MID
LEVEL RIDGE CENTERED OVER THE CENTRAL PART OF THE COUNTRY WILL
EXTEND INTO OUR REGION FROM THE WEST. THIS WILL LEAD TO DRY
CONDITIONS WITH TEMPS SATURDAY NIGHT THROUGH MONDAY SLIGHTLY BELOW
NORMAL. MEDIUM RANGE MODELS ARE SHOWING THE NEXT POSSIBLE
DISTURBANCE AND CHANCE OF SHOWERS AND STORMS ROUNDING THE MID LEVEL
RIDGE AND MOVING ACROSS OUR AREA SOMETIME IN THE TUESDAY TO
WEDNESDAY NIGHT TIME FRAME. FOR NOW WILL BRING A SLIGHT CHANCE POP
INTO NORTHERN PORTIONS OF THE AREA FOR TUESDAY... WITH SLIGHT CHANCE
EVERYWHERE FOR WEDNESDAY. GIVEN THE TIME RANGE (DAY 6-7)... TIMING
OF SUCH DISTURBANCES REMAIN DIFFICULT IF THIS PART OF THE FORECAST.
AS SURFACE HIGH PRESSURE SLIPS TO THE SOUTH OF THE REGION... EXPECT
WE WILL SEE A WARM UP ON TUESDAY AND WEDNESDAY BACK TO SEASONAL
NORMS.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 200 AM THURSDAY...
IFR TO LIFR CIGS AND MVFR VSBYS EXPECTED ESPECIALLY AT
KINT/KGSO/KRWI THROUGH AROUND 12Z... THEN MVFR TO VFR CIGS AND VFR
VSBYS THIS AFTERNOON AND TONIGHT. THERE IS A CHANCE OF BRIEF MVFR TO
IFR CIGS/VSBYS WITH A THUNDERSTORM AT ALL SITES THIS AFTERNOON AND
EVENING.
LOOKING AHEAD:
A COLD FRONT WILL CROSS CENTRAL NC AND RESULT IN ANOTHER ROUND OF
SHOWERS AND STORMS...PARTICULARLY AT SOUTHERN AND EASTERN TERMINALS
WHERE THE TIMING OF THE FRONTAL PASSAGE WILL COINCIDE MORE CLOSELY
WITH PEAK DIURNAL HEATING/DESTABILIZATION. CALM TO LIGHT
NORTHEASTERLY LOW LEVEL FLOW IN MODIFIED CANADIAN SURFACE HIGH
PRESSURE MAY THEN RESULT IN VERY SHALLOW PRE-DAWN RADIATION FOG THIS
WEEKEND...MAINLY AT KRWI.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...HARTFIELD
SHORT TERM...CBL/KRR
LONG TERM...BSD
AVIATION...BADGETT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
200 AM EDT THU AUG 22 2013
.SYNOPSIS...
A PRE-FRONTAL TROUGH WILL BE OVER THE REGION TODAY INTO EARLY
FRIDAY. A COLD FRONT WILL PUSH SOUTH THROUGH NORTH CAROLINA FRIDAY
NIGHT AND EARLY SATURDAY BRINGING COOLER AND DRIER AIR.
&&
.NEAR TERM /TONIGHT/...
AS OF 930 PM WEDNESDAY...
AFTER QUITE A WET LATE AFTERNOON THROUGH EARLY EVENING ESPECIALLY IN
THE SOUTHEAST CWA... THE REMAINDER OF THE NIGHT SHOULD TREND MUCH
DRIER FOR MOST OF CENTRAL NC. AN AREA OF STRATIFORM RAIN COVERS MUCH
OF THE COASTAL PLAIN... IN THE WAKE OF THE DISORGANIZED BAND OF
STORMS NOW MOVING INTO COASTAL NC. MOST CONVECTION-ALLOWING MODELS
AGREE ON NO SIGNIFICANT ADDITIONAL DEVELOPMENT OVERNIGHT... BUT ONE
EXCEPTION IS THE HRRR WHICH SUGGESTS THAT THE BAND OF CONVECTION NOW
EXTENDING FROM CENTRAL WV INTO SW VA/FAR NW NC (ASSOCIATED WITH DPVA
WITHIN THE MID LEVEL TROUGH) WILL PROGRESS EASTWARD OVER THE NEXT
SEVERAL HOURS... BRUSHING ACROSS THE NRN COUNTIES OF CENTRAL NC.
DEEP LAYER BULK SHEAR WILL REMAIN MARGINAL AT AROUND 25 KTS... BUT
THE RAP INDICATES ELEVATED INSTABILITY (MLCAPE OVER 1000 J/KG)
HOLDING THROUGH THE NIGHT. WITH ABOUT 30 METERS OF HEIGHT FALLS
ANTICIPATED OVERNIGHT IN NRN NC WITH THE TROUGH SHIFTING SLOWLY
EASTWARD JUST TO OUR NW... THIS MAY PROVIDE ENOUGH IMPETUS FOR THESE
STORMS TO HOLD TOGETHER AS THEY PUSH EASTWARD. ONCE THE
POST-CONVECTION RAIN CLEARS OUT OF THE EAST IN THE NEXT HOUR OR
SO... WILL RETAIN AN ISOLATED STORM MENTION OVERNIGHT EVERYWHERE
EXCEPT FOR SCATTERED COVERAGE ACROSS THE NORTH. TEMPS ARE ALREADY
VERY CLOSE TO THEIR ANTICIPATED OVERNIGHT LOWS... SO EXPECT READINGS
TO DIP JUST ANOTHER CATEGORY OR SO OVERNIGHT... RESULTING IN LOWS
69-73. -GIH
&&
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 310 PM WEDNESDAY...
MEAN FLOW WILL BECOME WESTERLY IN THE WAKE OF THE MID/UPPER TROUGH
EXITING THE AREA BETWEEN 12 TO 18Z...FINALLY DRYING OUT THE
THE ABNORMALLY MOIST(PWATS 1.75-2.00 INCHES)AIRMASS THAT HAS BEEN IN
PLACE OVER THE PAST SEVERAL DAYS. THIS DRYING ALONG WITH STRONG
SYNOPTIC SCALE SUBSIDENCE IN THE WAKE OF THE EXITING TROUGH WILL
LIKELY GO A LONG WAYS IN COUNTERACTING AFTERNOON HEATING AND
RESULTANT DESTABILIZATION TO KEEP CONVECTION AT A MINIMUM THURSDAY
AFTERNOON...ESPECIALLY WEST OF US 1. CONVECTIVE ALLOWING MODELS
STRONGLY SUPPORT THE ABOVE RATIONALE...AND AS SUCH HAVE OPTED TO
CUT POPS A BIT WITH SLIGHT/ISOLATED CHANCE IN THE WEST TO SMALL
CHANCE IN THE EAST. DRY THURSDAY NIGHT UNTIL THE ARRIVAL OF THE
COLD FRONT ON FRIDAY.
FULL SUN THICKNESSES WILL FINALLY BE REALIZED ALLOWING NEAR NORMAL
HIGHS IN THE UPPER 80S TO AROUND 90. LOWS THURSDAY NIGHT IN THE
UPPER 60S TO LOWER 70S.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 250 PM WEDNESDAY...
FRIDAY...SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE ON FRIDAY
AS A COLD FRONT MOVES THROUGH THE AREA AND MOISTURE REMAINS
SUFFICIENTLY HIGH (PWAT VALUES 1.75-2 INCHES). MODELS INDICATE
MODERATE INSTABILITY DEVELOPING DURING THE DAY ON FRIDAY...HOWEVER
GIVEN THAT THE STRONGER SHORT WAVE TROUGH WILL HAVE MOVED EAST OF
THE REGION BY FRIDAY MORNING...WEAK SHEAR (GENERALLY LESS THAN 20
KNOTS) IS PROGGED TO BE OVER THE REGION AND SHOULD THEREFORE LIMIT
ANY STORM ORGANIZATION. RAIN CHANCES SHOULD DIMINISH FROM NORTH TO
SOUTH FRIDAY NIGHT AS THE FRONT MOVES TOWARDS THE SC BORDER. HIGHS
WILL LIKELY BE IN THE MID/UPPER 80S TO NEAR 90 DEGREES WITH
OVERNIGHT LOWS GENERALLY IN THE MID/UPPER 60S TO NEAR 70 DEGREES
ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA.
SATURDAY THROUGH TUESDAY...LOWER DEEP LAYER MOISTURE WILL FILTER IN
BEHIND THE DEPARTING FRONT AS STRONG HIGH PRESSURE (ESPECIALLY FOR
AUGUST) BUILDS INTO THE AREA. THIS WILL RESULT IN A MOSTLY DRY
FORECAST...ALTHOUGH THERE COULD BE A COUPLE OF SHOWERS EARLY
SATURDAY MAINLY ACROSS THE SOUTH IN THE VICINITY OF THE SOUTHWARD
SINKING FRONT. DIURNAL TYPE RAIN CHANCES MAY BEGIN TO INCREASE BY
THE MIDDLE OF NEXT AS THE HIGH STARTS TO WEAKEN OVER THE AREA. TEMPS
WILL GENERALLY BE IN THE LOW/MID 80S...WITH A GRADUAL REBOUND BY
EARLY/MID NEXT WEEK.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 200 AM THURSDAY...
IFR TO LIFR CIGS AND MVFR VSBYS EXPECTED ESPECIALLY AT
KINT/KGSO/KRWI THROUGH AROUND 12Z... THEN MVFR TO VFR CIGS AND VFR
VSBYS THIS AFTERNOON AND TONIGHT. THERE IS A CHANCE OF BRIEF MVFR TO
IFR CIGS/VSBYS WITH A THUNDERSTORM AT ALL SITES THIS AFTERNOON AND
EVENING.
LOOKING AHEAD:
A COLD FRONT WILL CROSS CENTRAL NC AND RESULT IN ANOTHER ROUND OF
SHOWERS AND STORMS...PARTICULARLY AT SOUTHERN AND EASTERN TERMINALS
WHERE THE TIMING OF THE FRONTAL PASSAGE WILL COINCIDE MORE CLOSELY
WITH PEAK DIURNAL HEATING/DESTABILIZATION. CALM TO LIGHT
NORTHEASTERLY LOW LEVEL FLOW IN MODIFIED CANADIAN SURFACE HIGH
PRESSURE MAY THEN RESULT IN VERY SHALLOW PRE-DAWN RADIATION FOG THIS
WEEKEND...MAINLY AT KRWI.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...HARTFIELD
SHORT TERM...CBL
LONG TERM...KRR
AVIATION...BADGETT
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
359 AM EDT THU AUG 22 2013
.SYNOPSIS...
A COLD FRONT OVER MICHIGAN WILL MOVE ACROSS THE AREA THIS
AFTERNOON AND EVENING. HIGH PRESSURE THEN BUILDS BACK INTO THE
REGION FOR FRIDAY INTO THE WEEKEND. ANOTHER WEATHER SYSTEM WILL
AFFECT THE AREA EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AN UPPER TROF IS MOVING OUT OF EXTREME EASTERN OHIO EARLY THIS
MORNING...IT IS TAKING THE CLOUDS WITH IT. A COLD FRONT WILL BE
MOVING THROUGH THE FORECAST AREA THIS AFTERNOON AND EVENING...THE
ISSUE/DILEMMA IS THE TIMING OF THUNDERSTORMS AND WILL THEY BE
SEVERE. AT 330 AM EDT THE AREA OF SHOWERS AND THUNDERSTORMS OVER
MICHIGAN WAS WEAKENING. MY PLAN BASED ON THE HRRR AND SOME OF THE
MODELS IS TO HAVE A CHANCE OF SHOWERS THIS AM OVER NORTHWEST OHIO
AND THEN A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS ESPECIALLY
INLAND THIS AFTERNOON AS THE FRONT MOVES IN AND WE GET SOME
HEATING. IT IS STILL NOT CLEAR IF ALL THE THUNDERSTORMS WILL
DEVELOP OVER NORTHERN OHIO AND NW PA OR WILL SOME THUNDERSTORMS
MOVE IN FROM MICHIGAN. AT THIS TIME GOING WITH NOT MUCH MOVING IN
FROM MICHIGAN SO KEEPING MOST OF THE ACTIVITY OVER THE INLAND
AREAS AND SCATTERED ALONG THE LAKESHORE.
THE HIGHS ARE TOUGH TODAY IT ALL DEPENDS ON THE CLOUD COVER. I THINK
WE SHOULD HAVE SOME SUNSHINE. WENT CLOSE TO THE WARMER GUIDANCE.
ALSO THE CLOUD COVER WILL DETERMINE WHETHER SOME OF THE
THUNDERSTORMS COULD BE SEVERE. SINCE THE CLOUDS WITH THE COMPLEX
OVER MICHIGAN ARE DECREASING WE SHOULD GET SOME CAPE SO ISOLATED
SEVERE THUNDERSTORMS ARE POSSIBLE. THIS WILL BE MENTIONED IN THE
HAZARDOUS WEATHER OUTLOOK.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
HIGH PRESSURE IS BUILDING TONIGHT AS THE COLD FRONT WILL BE ACROSS
THE INLAND AREAS BY 6 PM EDT. SOME SHOWERS AND THUNDERSTORMS WILL
LINGER EARLY IN THE EVENING BEFORE IT DRIES OUT. SOME OF THE MODELS
LIKE THE NAM AND THE CANADIAN MODEL TRY TO HANG THE COLD FRONT UP
OVER LAKE ERIE THIS EVENING. AT THIS TIME LEANING TOWARD THE GFS AND
ECMWF WHICH PUSHES THE FRONT THROUGH. THIS SEEMS REASONABLE BASED
ON WHAT IS GOING ON UPSTREAM AND THE STRENGTH OF THE HIGH.
A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE AREA FRIDAY AND BE IN
CONTROL SATURDAY AND THEN SLIDE SOUTHEAST ON SUNDAY. AT THIS TIME A
DRY FORECAST WITH BELOW NORMAL TEMPERATURES FOR FRIDAY AND SATURDAY
AND THEN RECOVERING ON SUNDAY BACK TO NORMAL AS THE RIDGE WEAKENS
AND A SOUTHWEST FLOW DEVELOPS AGAIN. USED A BLEND OF GUIDANCE FOR
THE TEMPERATURES.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
BIG BUBBLE FINALLY PUSHES EAST IN THE UPPER LEVEL PATTERN. THE
PERSISTENT UPPER LEVEL RIDGE OVER THE WESTERN UNITED STATES WILL
COVER THE ENTIRE UNITED STATES AND BE CENTERED OVER THE MISSISSIPPI
RIVER VALLEY THROUGH MUCH OF THE EXTENDED FORECAST PERIOD.
ACTUALLY...THE LARGE UPPER LEVEL HIGH PRESSURE CENTER BUILDS OVER
THIS REGION DURING THE PERIOD HELPING TO STRENGTHEN THE CAUSE FOR
WARMER RETURN BACK TO SUMMER WEATHER.
THE ONLY FLY IN THE OINTMENT IS THE FACT THAT THE LOCAL AREA REMAINS
ON THE UPPER NORTHEAST PORTION OF THE RIDGE ALLOWING A FEW
SHORTWAVES TO DIVE DOWN ACROSS THE REGION AND BRING WITH IT A SUPPLY
OF MOISTURE AND THE THREAT FOR SHOWERS AND THUNDERSTORMS. MOISTURE
MAY BE LIMITED WITH THESE FEATURES AS THEY WILL NEED TO TRAVERSE
OVER A LARGE LAND MASS BEFORE ARRIVING HERE. SO WILL KEEP THE
MENTION OF SHOWERS AND THUNDERSTORMS JUST ABOUT EACH PERIOD.
AS MENTIONED ABOVE...FAIRLY STRONG WARM AIR ADVECTION WILL RETURN TO
THE FORECAST AREA DURING THE EXTENDED PERIODS. POTENTIAL EXISTS TO
SEE 90 DEGREES...ESPECIALLY IN THE WESTERN HALF OF THE FORECAST AREA
WHERE IT IS CLOSER TO THE UPPER LEVEL RIDGE. SOME SHOWER ACTIVITY IN
THE EAST MAY HELP KEEP TEMPERATURES OUT OF THE 90S.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
A LINE OF CONVECTION CONTINUES TO MOVE SOUTHEAST OUT OF SOUTHERN
LOWER MICHIGAN. THIS ACTIVITY IS JUST AHEAD OF THE COLD FRONT AT
THIS TIME. THE ACTIVITY SHOULD MOVE SOUTHEAST TOWARD TOLEDO AND
FINDLAY BY 12Z THIS MORNING AND THEN SPREAD EAST ACROSS THE REST
OF THE AREA THROUGHOUT THE MORNING. THE OTHER PROBLEM WILL BE FOG
DEVELOPMENT ACROSS THE AREA. WINDS SHOULD HELP KEEP DENSE FOG FROM
DEVELOPING ALL LOCATIONS BUT THERE IS A POSSIBILITY FOR
VISIBILITIES TO DROP TO AROUND 2 MILES AT AKRON CANTON AND
YOUNGSTOWN. CONVECTION MOVES SOUTH AND EAST OF THE AREA THIS
AFTERNOON. THE HOPE IS THAT FRONT DOES NOT STALL OVER THE AREA AND
KEEP A THREAT GOING FOR SHOWERS AND THUNDERSTORMS INTO THE EVENING.
OUTLOOK...NON-VFR IN FOG/MIST LATE TONIGHT AND FRIDAY NIGHT. MVFR
POSSIBLE MONDAY.
&&
.MARINE...
WINDS WILL BE ON THE INCREASE ACROSS THE LAKE TODAY AHEAD OF THE
COLD FRONT. FRONT LOOKS LIKE IT SHOULD SLIP SOUTH OF THE AREA BUT A
REINFORCING COLD FRONT STALLS JUST NORTH OF THE LAKE TODAY AND THEN
GRADUALLY SHIFTS SOUTH OF THE LAKE TONIGHT. MAY NEED A SMALL CRAFT
ADVISORY FOR A PERIOD LATE TONIGHT INTO FRIDAY...ESPECIALLY FROM
ABOUT CONNEAUT WEST. WINDS DIMINISH FAIRLY QUICKLY ON FRIDAY
ALLOWING WAVES TO SUBSIDE TO A FOOT OR LESS BY EVENING. A SLIGHT
INCREASE IN WAVES EXPECTED FRIDAY NIGHT WITH A LIGHT CHOP INTO EARLY
SATURDAY MORNING. THEN...LAKE SETTLES NICELY BY SUNDAY INTO SUNDAY
NIGHT WITH A SLIGHT INCREASE MONDAY WITH 1 TO 3 FOOTERS MAINLY NORTH
2/3RD`S OF THE LAKE.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...LOMBARDY
AVIATION...LOMBARDY
MARINE...LOMBARDY
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
250 AM EDT THU AUG 22 2013
.SYNOPSIS...
MID/UPPER LEVEL DISTURBANCE CROSSES TODAY. COLD FRONT
TONIGHT AND FRIDAY. HIGH PRESSURE FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPR LOW SHOULD BE E OF AREA BY MORNING. WILL KEEP LOW POPS THRU
MORNING TO ACCOUNT FOR ANY POP UP SHRA WITH LIFT WITH UPR LVL SYS.
ATTENTION THEN TURNS UPSTREAM FOR POTENTIALLY ACTIVE AFTN ACROSS
THE AREA. MDLS HAVE BEEN FAIRLY CONSISTENT IN PAST 24 HRS ON
BRINGING DOWN A DISTURBANCE AND PREFRONTAL LINE OF CONVECTION
LATER TDY. THIS SHOWS UP NICELY IN THE H7-H5 LYR OMEGA FIELDS
ALONG WITH MID LVL PVA. THE QUESTION IS HOW MUCH INSTABILITY CAN
BE REALIZED WITH POTENTIAL FOR DEBRIS CLDS TO WORK IN HERE THIS
MORNING. WILL HEDGE THAT BULK OF DEBRIS CLDS WILL STAY W OF
AREA...MORE INTO KY...AND DISSIPATE AS RUC SUGGESTS. WILL LEAN ON
FASTER NAM/WRF MDLS FOR TIMING THIS AFTN...ALTHOUGH EVEN SLOWER
GFS NOT TOO FAR BEHIND. WILL BRING IN LKLY POPS INTO SE OH 17 TO
19Z AND LOWLANDS/NE KY 19 TO 21Z...INTO MTNS/SW VA 22 TO 00Z.
THERE IS SOME CONCERN THIS TRIES TO SLOW DOWN A BIT ACROSS S
ZONES...IE SW VA...THIS EVE. OVERALL...THOUGH...THIS SHOULD MOVE
RIGHT ALONG WITH STORM MOTIONS 15 TO 20 KTS.
AS FOR WATER CONCERNS...THERE WERE SOME PLACES THAT
GOT A GOOD HIT YESTERDAY...MAINLY ALONG I64 CORRIDOR FROM HTS TO
CRW. PWATS SURGE RIGHT BACK UP NEAR 2 INCHES WITH THIS FEATURE
WHICH MEANS DOWNPOURS A GOOD BET. ELECTED TO CODE UP A HVY RA
MENTION IN WX GRIDS WITH CONVECTION. WITH DECENT STORM MOTIONS AND
MOVEMENT LESS CONDUCIVE TO TRAINING...WILL FORGO A WATCH ATTM BUT
PUT A MENTION IN HWO FOR POSSIBLE STREET FLOODING AND LOW LYING
AREA CONCERNS.
ASSUMING MDLS ARE CORRECT...SHOULD SEE A LULL THIS EVE BEFORE SFC
FRONT APPROACHES. MDLS SEEM TO PLACE FRONT ALONG OH RVR BY END OF
NEAR TERM. UNCLEAR ON HOW ACTIVE ACTUAL BOUNDARY WILL BE GIVEN
NIGHT TIME HRS. HOWEVER...WITH DECENT LIFT SHOWN...WILL CODE UP
SOME HIGH CHC POPS OVERNIGHT AND KEEP A SMALL THUNDER THREAT IN.
CANT RULE OUT A FEW SVR CELLS THIS AFTN...MAINLY WIND. BUT
AGAIN...DOWNPOURS BIGGEST ISSUE.
FOR TEMPS...HEDGED TOWARD LAMP GUIDANCE ONCE AGAIN GIVEN ITS
RECENT PERFORMANCE. THIS RESULTED IN MINOR TWEAKS HERE AND THERE
FROM PREV FCST. GENERALLY LOW TO MID 80S ONCE AGAIN. LEANED ON
WARM SIDE TONIGHT GIVEN ABUNDANCE OF MOISTURE ABOUT THE AREA AND
SHRA THREAT.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
MODELS STILL HAVE SOME TIMING DIFFERENCES ON FRIDAY WITH THE COLD
FRONT AND ASSOCIATED MOISTURE. NAM CONTINUES TO BE THE SLOWEST WHILE
THE CANADIAN IS THE FASTEST. GFS AND ECMWF LIE IN THE MIDDLE. WITH
NO OBVIOUS REASON WHY ONE MODEL WOULD BE BETTER THAN THE
OTHER...WILL CONTINUE TO RUN A MIDDLE OF THE ROAD SOLUTION.
HIGH PRESSURE THEN TAKES OVER FOR THE WEEKEND...PROVIDING DRY
WEATHER AND LOW HUMIDITY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
UPPER RIDGE BUILDING OVER THE SOUTHERN PLAINS THROUGH THE LONG TERM
FORECAST. THE CENTER OF THE 500MB HIGH GENERALLY DRIFTS AROUND OVER
KS/OK/MO...WHICH KEEPS OUR REGION IN NW FLOW ALOFT...WITH SEVERAL
RIPPLES DROPPING THROUGH. TIMING/LOCATION OF EACH INDIVIDUAL WAVE
VARY BETWEEN GFS/ECMWF. SOME LOW LEVEL MOISTURE SHOULD BE AVAILABLE
WITH SE SURFACE FLOW...BUT JUST HOW MUCH WILL DEPEND ON WHERE
SURFACE HIGH IS. IF IT STAYS OVER THE SE STATES...WE WOULD GET AT
LEAST SOME MOISTURE ADVECTION FROM THE GULF...WHILE IF IT THE
SURFACE HIGH DRIFTS FARTHER WEST AS THE ECMWF HINTS...THAT RICHER
MOISTURE FLOW COULD GET CUT OF. DUE TO THIS UNCERTAINTY...STAYED
PRETTY CLOSE TO WPC GUIDANCE. WITH 500 HEIGHTS OVER 590DAM...LOOKS
LIKE A WARM STRETCH...WITH LOWLAND HIGHS IN THE UPPER 80S AND EVEN
SOME 90S NEXT WEEK. COULD ACTUALLY BE WARMER IF WE DO NOT HAVE THE
GOOD MOISTURE FLOW...AS THE DRIER AIR WOULD BE EASIER TO WARM.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
06Z THURSDAY THRU 06Z FRIDAY...
UPR S/W TROF PUSHES E OF AREA AFTER 12Z. ISOLD SHRA THREAT THRU
MORNING...BUT CHC NOT GREAT ENOUGH TO INCLUDE IN TAFS. DIFFICULT FG
FCST THRU MORNING WITH VARIOUS AREAS OF HI CLDS...MAINLY ACROSS
THE N. ALSO A SLIGHT PUFF AT SFC TO COMPLICATE FG FORMATION
DESPITE RAINS YESTERDAY. PLAYED UP FG INITIALLY KCRW/KBKW BEFORE
TRYING TO LIFT OUT BY 09Z WITH EXPECTATION THAT HI CLDS MOVE IN
AND A SLIGHT SFC WIND BECOMES REALIZED. ELSEWHERE...ONLY HAVE MVFR
FG IN. THERE IS A CONCERN FOR SOME LOW STRATUS ACROSS KCKB AND
KEKN THRU MORNING BUT ELECTED TO LEAVE OUT OF TAFS ATTM AND FOLLOW
TRENDS FOR ANY AMENDMENTS.
FG LIFTS AFTER 12Z FOR A RETURN TO VFR CONDITIONS. HAVE SOME CU
FORMING BY MID MORNING WITH AREA IN BETWEEN WX SYS. EXPECT UPR
DISTURBANCE TO MAKE A RUN THRU AREA AFTER 18Z FROM NW...WELL AHEAD
OF SFC FRONT. AS SUCH...HAVE A PREDOMINATE SHRA/VCTS IN TAFS FOR
EXPECTED CONVECTIVE LINE IN AFTN. KEPT PREDOMINATE VFR THOUGH
GIVEN AT THIS RANGE.
THINGS MAY QUIET DOWN AFTER 00Z TONIGHT UNTIL SFC FRONT APPROACHES
WITH PERHAPS ANOTHER ROUND OF SHRA. NOT EXPECTING MUCH IN WAY OF
DENSE FG TONIGHT WITH ABUNDANCE OF CLDS ACROSS THE AREA.
SHOWERS AND THUNDERSTORMS WILL FIRE BACK UP AGAIN AFTER 16-18Z
THURSDAY AS A COLD FRONT APPROACHES FROM THE NORTH. EXPECT BRIEF
MVFR/IFR CONDITIONS IN VICINITY OF STORMS.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: FOG MAY HOLD FOR CRW/BKW LONGER THAN
EXPECTED. MVFR STRATUS MAY DEVELOP FOR KCKB/KEKN THRU 12Z. TIMING
OF CONVECTION THIS AFTN MAY VARY A FEW HRS.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE THU 08/22/13
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13
CRW CONSISTENCY M M L L L L H M H H H H
HTS CONSISTENCY M M L L L H H M H H H H
BKW CONSISTENCY L H H H H L L H H H H H
EKN CONSISTENCY L L L L L L L H H H H H
PKB CONSISTENCY H H L L L L H H H H H H
CKB CONSISTENCY L L L L L H H H H H H H
AFTER 06Z FRIDAY...
AREAS OF IFR IN DENSE FOG/LOW STRATUS MOST MORNINGS THIS
WEEK...ESPECIALLY ALONG THE RIVERS. IFR IN SHOWERS AND THUNDERSTORMS
FRIDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30
NEAR TERM...30
SHORT TERM...RPY
LONG TERM...MZ
AVIATION...30
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
248 AM EDT THU AUG 22 2013
.SYNOPSIS...
MID/UPPER LEVEL DISTURBANCE CROSSES TODAY. COLD FRONT
TONIGHT AND FRIDAY. HIGH PRESSURE FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPR LOW SHOULD BE E OF AREA BY MORNING. WILL KEEP LOW POPS THRU
MORNING TO ACCOUNT FOR ANY POP UP SHRA WITH LIFT WITH UPR LVL SYS.
ATTENTION THEN TURNS UPSTREAM FOR POTENTIALLY ACTIVE AFTN ACROSS
THE AREA. MDLS HAVE BEEN FAIRLY CONSISTENT IN PAST 24 HRS ON
BRINGING DOWN A DISTURBANCE AND PREFRONTAL LINE OF CONVECTION
LATER TDY. THIS SHOWS UP NICELY IN THE H7-H5 LYR OMEGA FIELDS
ALONG WITH MID LVL PVA. THE QUESTION IS HOW MUCH INSTABILITY CAN
BE REALIZED WITH POTENTIAL FOR DEBRIS CLDS TO WORK IN HERE THIS
MORNING. WILL HEDGE THAT BULK OF DEBRIS CLDS WILL STAY W OF
AREA...MORE INTO KY...AND DISSIPATE AS RUC SUGGESTS. WILL LEAN ON
FASTER NAM/WRF MDLS FOR TIMING THIS AFTN...ALTHOUGH EVEN SLOWER
GFS NOT TOO FAR BEHIND. WILL BRING IN LKLY POPS INTO SE OH 17 TO
19Z AND LOWLANDS/NE KY 19 TO 21Z...INTO MTNS/SW VA 22 TO 00Z.
THERE IS SOME CONCERN THIS TRIES TO SLOW DOWN A BIT ACROSS S
ZONES...IE SW VA...THIS EVE. OVERALL...THOUGH...THIS SHOULD MOVE
RIGHT ALONG WITH STORM MOTIONS 15 TO 20 KTS.
AS FOR WATER CONCERNS...THERE WERE SOME PLACES THAT
GOT A GOOD HIT YESTERDAY...MAINLY ALONG I64 CORRIDOR FROM HTS TO
CRW. PWATS SURGE RIGHT BACK UP NEAR 2 INCHES WITH THIS FEATURE
WHICH MEANS DOWNPOURS A GOOD BET. ELECTED TO CODE UP A HVY RA
MENTION IN WX GRIDS WITH CONVECTION. WITH DECENT STORM MOTIONS AND
MOVEMENT LESS CONDUCIVE TO TRAINING...WILL FORGO A WATCH ATTM BUT
PUT A MENTION IN HWO FOR POSSIBLE STREET FLOODING AND LOW LYING
AREA CONCERNS.
ASSUMING MDLS ARE CORRECT...SHOULD SEE A LULL THIS EVE BEFORE SFC
FRONT APPROACHES. MDLS SEEM TO PLACE FRONT ALONG OH RVR BY END OF
NEAR TERM. UNCLEAR ON HOW ACTIVE ACTUAL BOUNDARY WILL BE GIVEN
NIGHT TIME HRS. HOWEVER...WITH DECENT LIFT SHOWN...WILL CODE UP
SOME HIGH CHC POPS OVERNIGHT AND KEEP A SMALL THUNDER THREAT IN.
CANT RULE OUT A FEW SVR CELLS THIS AFTN...MAINLY WIND. BUT
AGAIN...DOWNPOURS BIGGEST ISSUE.
FOR TEMPS...HEDGED TOWARD LAMP GUIDANCE ONCE AGAIN GIVEN ITS
RECENT PERFORMANCE. THIS RESULTED IN MINOR TWEAKS HERE AND THERE
FROM PREV FCST. GENERALLY LOW TO MID 80S ONCE AGAIN. LEANED ON
WARM SIDE TONIGHT GIVEN ABUNDANCE OF MOISTURE ABOUT THE AREA AND
SHRA THREAT.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
EXITING UPPER LEVEL LOW PROVIDING MARGINAL INSTABILITY OUT AHEAD OF
AN APPROACHING COLD FRONT LATE THURSDAY AND FRIDAY WITH HIGH
PRESSURE GRADUALLY BUILDING IN THROUGH THE DAY ON SATURDAY...MODELS
ARE IN SOME DISAGREEMENT WITH REGARD TO COVERAGE AND LOCATION OF
PREFRONTAL PRECIP OUT AHEAD OF THE COLD FRONT EARLY FRIDAY BUT
PRIMARILY WENT WITH THE NAM SOLUTION...LATER FRIDAY THE FRONT SLOWLY
MOVES SOUTH WITH AN UPPER LEVEL TROUGH AXIS HINTING TOWARD THE
POSSIBILITY OF SHOWERS IN THE TRI-STATE AREA...WENT WITH SLIGHT
CHANCE POPS...WITH THE UPPER RIDGE BUILDING BY SATURDAY AND THE
SURFACE HIGH DEVELOPING IN RESPONSE WE`LL WARM NICELY BUT DID KEEP
SLIGHT CHANCE POPS IN THE EASTERN MTNS WITH DIURNAL/OROGRAPHIC
FORCING.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
UPPER RIDGE BUILDING OVER THE SOUTHERN PLAINS THROUGH THE LONG TERM
FORECAST. THE CENTER OF THE 500MB HIGH GENERALLY DRIFTS AROUND OVER
KS/OK/MO...WHICH KEEPS OUR REGION IN NW FLOW ALOFT...WITH SEVERAL
RIPPLES DROPPING THROUGH. TIMING/LOCATION OF EACH INDIVIDUAL WAVE
VARY BETWEEN GFS/ECMWF. SOME LOW LEVEL MOISTURE SHOULD BE AVAILABLE
WITH SE SURFACE FLOW...BUT JUST HOW MUCH WILL DEPEND ON WHERE
SURFACE HIGH IS. IF IT STAYS OVER THE SE STATES...WE WOULD GET AT
LEAST SOME MOISTURE ADVECTION FROM THE GULF...WHILE IF IT THE
SURFACE HIGH DRIFTS FARTHER WEST AS THE ECMWF HINTS...THAT RICHER
MOISTURE FLOW COULD GET CUT OF. DUE TO THIS UNCERTAINTY...STAYED
PRETTY CLOSE TO WPC GUIDANCE. WITH 500 HEIGHTS OVER 590DAM...LOOKS
LIKE A WARM STRETCH...WITH LOWLAND HIGHS IN THE UPPER 80S AND EVEN
SOME 90S NEXT WEEK. COULD ACTUALLY BE WARMER IF WE DO NOT HAVE THE
GOOD MOISTURE FLOW...AS THE DRIER AIR WOULD BE EASIER TO WARM.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
06Z THURSDAY THRU 06Z FRIDAY...
UPR S/W TROF PUSHES E OF AREA AFTER 12Z. ISOLD SHRA THREAT THRU
MORNING...BUT CHC NOT GREAT ENOUGH TO INCLUDE IN TAFS. DIFFICULT FG
FCST THRU MORNING WITH VARIOUS AREAS OF HI CLDS...MAINLY ACROSS
THE N. ALSO A SLIGHT PUFF AT SFC TO COMPLICATE FG FORMATION
DESPITE RAINS YESTERDAY. PLAYED UP FG INITIALLY KCRW/KBKW BEFORE
TRYING TO LIFT OUT BY 09Z WITH EXPECTATION THAT HI CLDS MOVE IN
AND A SLIGHT SFC WIND BECOMES REALIZED. ELSEWHERE...ONLY HAVE MVFR
FG IN. THERE IS A CONCERN FOR SOME LOW STRATUS ACROSS KCKB AND
KEKN THRU MORNING BUT ELECTED TO LEAVE OUT OF TAFS ATTM AND FOLLOW
TRENDS FOR ANY AMENDMENTS.
FG LIFTS AFTER 12Z FOR A RETURN TO VFR CONDITIONS. HAVE SOME CU
FORMING BY MID MORNING WITH AREA IN BETWEEN WX SYS. EXPECT UPR
DISTURBANCE TO MAKE A RUN THRU AREA AFTER 18Z FROM NW...WELL AHEAD
OF SFC FRONT. AS SUCH...HAVE A PREDOMINATE SHRA/VCTS IN TAFS FOR
EXPECTED CONVECTIVE LINE IN AFTN. KEPT PREDOMINATE VFR THOUGH
GIVEN AT THIS RANGE.
THINGS MAY QUIET DOWN AFTER 00Z TONIGHT UNTIL SFC FRONT APPROACHES
WITH PERHAPS ANOTHER ROUND OF SHRA. NOT EXPECTING MUCH IN WAY OF
DENSE FG TONIGHT WITH ABUNDANCE OF CLDS ACROSS THE AREA.
SHOWERS AND THUNDERSTORMS WILL FIRE BACK UP AGAIN AFTER 16-18Z
THURSDAY AS A COLD FRONT APPROACHES FROM THE NORTH. EXPECT BRIEF
MVFR/IFR CONDITIONS IN VICINITY OF STORMS.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: FOG MAY HOLD FOR CRW/BKW LONGER THAN
EXPECTED. MVFR STRATUS MAY DEVELOP FOR KCKB/KEKN THRU 12Z. TIMING
OF CONVECTION THIS AFTN MAY VARY A FEW HRS.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE THU 08/22/13
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13
CRW CONSISTENCY M M L L L L H M H H H H
HTS CONSISTENCY M M L L L H H M H H H H
BKW CONSISTENCY L H H H H L L H H H H H
EKN CONSISTENCY L L L L L L L H H H H H
PKB CONSISTENCY H H L L L L H H H H H H
CKB CONSISTENCY L L L L L H H H H H H H
AFTER 06Z FRIDAY...
AREAS OF IFR IN DENSE FOG/LOW STRATUS MOST MORNINGS THIS
WEEK...ESPECIALLY ALONG THE RIVERS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30
NEAR TERM...30
SHORT TERM...JM
LONG TERM...MZ
AVIATION...30
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
425 AM EDT THU AUG 22 2013
.SYNOPSIS...
AN UPPER LOW...CENTERED OVER THE LAUREL HIGHLANDS...WILL DRIFT
ACROSS THE SOUTHERN TIER OF PENNSYLVANIA THIS MORNING. WEAK RIDGING
IN THE WAKE OF THIS LOW WILL BE OVER THE REGION DURING THE MIDDAY
AND AFTERNOON HOURS...ACCOMPANIED BY GENERALLY FAIR WEATHER. A COLD
FRONT WILL PUSH SOUTHEAST ACROSS THE REGION LATE THURSDAY INTO EARLY
FRIDAY...FOLLOWED BY CANADIAN HIGH PRESSURE.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
REGIONAL IR SATELLITE AND RADAR LOOP AT 0815Z SHOWS EXPANDING
COVERAGE OF SHOWERS AND A FEW TSRA FROM THE LAUREL HIGHLANDS...EAST
TO THE LOWER SUSQ VALLEY. THIS CONVECTION WAS OCCURRING WITHIN A
REGION OF MDTLY STRONG UPPER DIFFLUENCE AND DIFFERENTIAL PVA JUST
AHEAD OF A SLOW-MOVING UPPER LOW. ALSO AIDING THIS CONVECTION WAS
THE VERY JUICY AIRMASS WITH LAYER PWATS IN THE 1.5-2 INCH
RANGE...ALONG WITH STRENGTHENING 850-700 MB FRONTOGENESIS.
LATEST HRRR AND RUC CONTINUES TO PAINT LIGHT TO MODERATE RAINFALL
AMOUNTS OVER THE NEXT SEVERAL HOURS ACROSS APPROXIMATELY THE
SOUTHERN 1/3 TO 1/2 OF THE CWA AS THE UPPER LOW TRACKS SLOWLY EAST
AND PROVIDES LIFT OF THE VERY MOIST AND UNSTABLE AIR. MOST OF THE
SHOWERS AND EMBEDDED TSRA WILL BE NEAR AND JUST TO THE SOUTH OF A
LINE FROM KAOO TO KSEG AND KAVP...BEFORE FOCUSING OVER THE ECENT
MTNS /SCHUYLKILL CTY AND VCNTY/ BETWEEN 10-13Z.
SFC DWPTS RANGE FROM THE U60S AND L70S IN THE SOUTH....TO THE UPPER
50S AND LOWER 60S IN THE NORTH...WHERE THE BLYR WILL LIKELY REMAIN
TOO DRY TO SUPPORT ANY CONVECTION.
EXTENSIVE CLOUD COVER AND LOW LVL MOISTURE WILL RESULT IN THE
WARMEST EARLY MORNING IN SOME TIME WITH LOWS RANGING FROM THE UPPER
50S OVR THE N MTNS...TO ARND 70F ACROSS THE LOWER SUSQ VALLEY.
THE REMNANTS OF UPPER LOW SHOULD TAKE UNTIL ARND MIDDAY TO CLEAR THE
ERN...SO WILL CARRY A CHC POPS FOR SHRA/TSRA THERE UNTIL THAT
TIME. RIDGING IN WAKE OF DEPARTING UPPER LOW SHOULD BRING A PERIOD
OF DRY CONDITIONS TO MOST OF CENTRAL PENN ON THURS BEFORE COLD FRONT
FROM THE GLAKES BRINGS ANOTHER THREAT OF CONVECTION LATE IN THE DAY
NW /AND MORE LIKELY BEGINNING THIS EVENING ACROSS THE CENTRAL MTNS/.
A RIBBON OF HIGHER PWATS BETWEEN 1.5 AND 1.75 INCHES AND SLIGHTLY
STEEPER MID-LEVEL LAPSE RATES SHOULD SUPPORT SCT SHRA/TSRA
DEVELOPING ACROSS THE NW MTNS /AHEAD OF A COLD FRONT/ DURING THE MID
TO LATE AFTN...WITH THE CONVECTION SLIDING SE THRU THE REST OF THE
REGION BETWEEN 02-06Z FRIDAY.
HIGH TEMPS THIS AFTERNOON WILL REACH THE MID AND UPPER 80S ACROSS
THE CENTRAL AND SE VALLEYS...AND AROUND 80F OVER THE HIGHER TERRAIN
OF NRN AND WRN PENN.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
AS NOTED ABOVE...THE TIMING OF THE SFC COLD FRONT AND ASSOCIATED
SHRA/TSRA WILL BE DURING THE FIRST HALF OF THE OVERNIGHT HOURS.
POPS WILL DIMINISH STEADILY AFTER MIDNIGHT AND BECOME CONFINED TO
THE SOUTHERN TIER OF THE STATE BEFORE DAYBREAK.
THE MEAN LOW-MID LEVEL FLOW VEERS AROUND TO THE NNW FRIDAY...
ALLOWING DEEP DRYING TO ADVECT INTO THE REGION DURING THE DAY. MAX
TEMPS FRIDAY WILL COOL BY A FEW TO SVRL DEG F COMPARED TO THURSDAY/S.
SFC DEWPOINTS WILL RETREAT BACK TO VERY COMFORTABLE LEVELS IN THE
UPPER 40S /NW/...AND MID 50S /SE/ FRIDAY AFTERNOON...SETTING THE
STAGE FOR A COOL LATE AUGUST NIGHT FRIDAY NIGHT.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
OVERVIEW...THE LATEST MODEL AND ENSEMBLE GUIDANCE REMAINS IN VERY
GOOD AGREEMENT IN THE LARGE SCALE MEAN FLOW PATTERN CONSISTING OF
A BUILDING/STRONG UPPER RIDGE OVER THE PLAINS/MS VLY WITH TROUGHS
JUST OFF THE WEST AND EAST COASTS. HOWEVER...THE PCPN PATTERN OVER
THE LOCAL AREA WILL BE MODULATED BY SHORTWV IMPULSES DIVING ESEWD
DOWN THE NERN/FRONT SIDE OF THE RIDGE WITHIN A NWLY FLOW ALOFT.
THEREFORE DESPITE ABOVE AVG CONFIDENCE IN THE MEAN PATTERN...THE
SMALLER SCALE EMBEDDED SYSTEM TIMING AND LOCAL QPF/SENSIBLE WX
IMPACT IS MORE UNCERTAIN. AS SUCH...THE FINAL DAY 3-7 GRIDS WERE
DERIVED USING A CONSENSUS BLEND IN AN EFFORT TO MITIGATE THE LOWER
CONFIDENCE IN THE SFC DETAILS AND TO BEHOLD REASONABLE CONTINUITY
THE FCST.
A MODIFIED CANADIAN HIGH PRESSURE SYSTEM WILL DOMINATE THE PATTERN
THROUGH THE WEEKEND...BRINGING RELATIVELY COOL NIGHTS WITH VALLEY
FOG AND COMFORTABLE HUMIDITY DURING THE DAY. EXPECT A MORE UNSETTLED
AND INCREASINGLY HUMID PATTERN TO EVOLVE THRU THE FIRST PART OF NEXT
WEEK..AS THE FOCUS SHIFTS TO UPPER-LEVEL DISTURBANCES CRESTING THE
PLAINS RIDGE AND DIVING ESEWD THRU THE GREAT LAKES TAKING AIM ON THE
NE STATES. MODELS SUGGEST THIS ENERGY MAY TRIGGER ONE OR MORE
ORGANIZED TSTM COMPLEXES AS THEY ROLL DOWN THE FRONT-SIDE OF THE
RIDGE.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
SOUTHERLY FLOW CONTINUES TO SPARK SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS ACROSS THE SOUTHERN HALF OF PA OVERNIGHT.
EXPECT VCTS IN MDT AND LNS...WITH SHOWERS AT JST. THE SHOWERS AND
JST SHOULD REDUCE CIGS AND VSBYS TO MVFR FOR A FEW HOURS...BEFORE
LIFTING NORTHWARD BY 09Z. ANY PRECIPITATION WILL REINFORCE LOW
LEVEL MOISTURE WHICH GIVEN THE CALMING WINDS...COULD ALLOW FOR
PATCHY FOG FROM 10Z THROUGH 14Z. AN APPROACHING COLD FRONT FROM
THE GREAT LAKES TODAY WILL ALLOW FOR A BETTER CHC FOR SHRA/TSRA.
THIS FRONT SHOULD PASS SOUTH OF THE REGION THURSDAY NIGHT...WITH
IMPROVING FLYING CONDS FOR FRI INTO THIS WEEKEND.
WITH VARYING TIMING...HAVE ONLY INCLUDED VCSH IN TAFS...BUT
REDUCTION IN CIG AND VSBYS WILL BE POSSIBLE.
OUTLOOK...
THU-THU NIGHT...MVFR POSSIBLE WITH SCT SHRA/TSRA.
FRI-MON...GENERALLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...LAMBERT
LONG TERM...LAMBERT/STEINBUGL
AVIATION...CERU/GARTNER
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
316 AM EDT THU AUG 22 2013
.SYNOPSIS...
AN UPPER LOW...NEAR MORGANTOWN WEST VIRGINIA...WILL DRIFT ACROSS THE
SOUTHERN TIER OF PENNSYLVANIA EARLY TODAY. WEAK RIDGING IN THE WAKE
OF THIS LOW WILL BE OVER THE REGION LATER THIS MORNING THROUGH THE
AFTERNOON HOURS...ACCOMPANIED BY GENERALLY FAIR WEATHER. A COLD
FRONT WILL PUSH SOUTHEAST ACROSS THE REGION LATE THURSDAY INTO EARLY
FRIDAY...FOLLOWED BY CANADIAN HIGH PRESSURE.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
REGIONAL IR SATELLITE AND RADAR LOOP SHOWS A CLUSTER OF SHOWERS AND
LOW-TOPPED TSRA DEVELOPING INVOF THE LAUREL HIGHLANDS...SOUTH INTO
THE MTNS OF WVA AT 05Z...WITHIN A REGION OF MDTLY STRONG UPPER
DIFFLUENCE AND DIFFERENTIAL PVA JUST AHEAD OF A SLOW-MOVING UPPER
LOW.
LATEST HRRR SHOWS THIS AREA OF CONVECTION BLOSSOMING TO THE
NORTHEAST ACROSS THE SCENT MTNS THROUGH DAYBREAK...REACHING THE I-80
CORRIDOR THROUGH THE MIDDLE SUSQ VALLEY AROUND AND SHORTLY AFTER
SUNRISE. 04Z RUC ALSO SHOWING SIGNS OF THIS POTENTIAL DVLPMT AND
TRACK OF CONVECTION EARLY TODAY...BASED ON IT/S WELL-DEFINED CHANNEL
OF 925-850 MB THETA-E CONVERGENCE SETTING UP NEAR AND JUST TO THE SE
OF A KJST TO KUNV AND KIPT LINE. MID LEVEL LAPSE RATES ARE ALSO
STEEPENING IN THIS AREA THROUGH THE MORNING HOURS...AND CAN BE SEEN
IN THE MOST UNSTABLE AIR WITH CURRENT...MU CAPE OF 1200-1500 J/KG IN
THE REGION BETWEEN KJST...KAOO...KUNV...AND KFIG.
CONSIDERING ALL OF THESE NEAR TERM WEATHER FACTORS...WILL BE
BOOSTING POPS TO REFLECT A BLEND OF ALL HIGH RES/NEAR TERM MODEL
GUIDANCE...THOUGH QPF WILL BE SIGNIFICANTLY UNDER THE LOCALLY
EXCESSIVE CONVECTIVE AMOUNTS /OF 1-3 INCHES/ GENERATED BY THESE
MODELS.
A SECOND AREA OF HEAVIER CONVECTION SHOULD SLIDE OFF WELL TO THE
SOUTH OF YORK AND LANCASTER COUNTIES THROUGH THE MID MORNING...WITH
THE LOWER SUSQ VALLEY SEEING ISOLATED TO SCTD SHOWERS BETWEEN
07-12Z.
SFC DWPTS RANGE FROM THE U60S AND L70S IN THE SOUTH....TO THE UPPER
50S AND LOWER 60S IN THE NORTH...WHERE THE BLYR WILL LIKELY REMAIN
TOO DRY TO SUPPORT ANY CONVECTION.
EXTENSIVE CLOUD COVER AND LOW LVL MOISTURE WILL RESULT IN THE
WARMEST NIGHT/EARLY MORNING IN SOME TIME WITH LOWS RANGING FROM ARND
60F OVR THE N MTNS...TO ARND 70F ACROSS THE LOWER SUSQ VALLEY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
REMNANTS OF UPPER LOW SHOULD TAKE UNTIL ARND MIDDAY TO CLEAR THE
SE COUNTIES...SO WILL CARRY A SLIGHT CHC OF A SHRA/TSRA DOWN THERE
UNTIL THAT TIME. RIDGING IN WAKE OF DEPARTING UPPER LOW SHOULD
BRING A PERIOD OF DRY CONDITIONS TO MOST OF CENTRAL PENN ON THURS
BEFORE COLD FRONT FROM THE GLAKES BRINGS ANOTHER THREAT OF
CONVECTION LATE IN THE DAY.
A RIBBON OF HIGHER PWATS BETWEEN 1.5 AND 1.75 INCHES AND SLIGHTLY
STEEPER MID-LEVEL LAPSE RATES SHOULD SUPPORT SCT SHRA/TSRA
DEVELOPING ACROSS THE NW MTNS THURSDAY AFTN AND SLIDING SE THRU
THE EVENING AND EARLY OVERNIGHT.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
OVERVIEW...THE LATEST MODEL AND ENSEMBLE GUIDANCE REMAINS IN VERY
GOOD AGREEMENT IN THE LARGE SCALE MEAN FLOW PATTERN CONSISTING OF
A BUILDING/STRONG UPPER RIDGE OVER THE PLAINS/MS VLY WITH TROUGHS
JUST OFF THE WEST AND EAST COASTS. HOWEVER...THE PCPN PATTERN OVER
THE LOCAL AREA WILL BE MODULATED BY SHORTWV IMPULSES DIVING ESEWD
DOWN THE NERN/FRONT SIDE OF THE RIDGE WITHIN A NWLY FLOW ALOFT.
THEREFORE DESPITE ABOVE AVG CONFIDENCE IN THE MEAN PATTERN...THE
SMALLER SCALE EMBEDDED SYSTEM TIMING AND LOCAL QPF/SENSIBLE WX
IMPACT IS MORE UNCERTAIN. AS SUCH...THE FINAL DAY 3-7 GRIDS WERE
DERIVED USING A CONSENSUS BLEND IN AN EFFORT TO MITIGATE THE LOWER
CONFIDENCE IN THE SFC DETAILS AND TO BEHOLD REASONABLE CONTINUITY
THE FCST.
HIGHLIGHTS...PUSH OF ABNORMALLY DRY AIR WITH BELOW NORMAL PWS
BEHIND THE THUR NGT FROPA APPEARS DELAYED BY ABOUT 6 HRS ON THE
12Z CYCLE...SUGGESTING A LOW CHC FOR SHOWERS ALONG THE SRN TIER
ZONES EARLY FRI. OTHERWISE...A MODIFIED CANADIAN HIGH PRESSURE
SYSTEM WILL DOMINATE THE PATTERN THROUGH THE WEEKEND..BRINGING
RELATIVELY COOL NIGHTS WITH VALLEY FOG AND COMFORTABLE HUMIDITY
DURING THE DAY. EXPECT A MORE UNSETTLED AND INCREASINGLY HUMID
PATTERN TO EVOLVE THRU THE FIRST PART OF NEXT WEEK..AS THE FOCUS
SHIFTS TO UPPER-LEVEL DISTURBANCES CRESTING THE PLAINS RIDGE AND
DIVING ESEWD THRU THE GREAT LAKES TAKING AIM ON THE NE STATES.
MODELS SUGGEST THIS ENERGY MAY TRIGGER ONE OR MORE ORGANIZED TSTM
COMPLEXES AS THEY ROLL DOWN THE FRONT-SIDE OF THE RIDGE.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
SOUTHERLY FLOW CONTINUES TO SPARK SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS ACROSS THE SOUTHERN HALF OF PA OVERNIGHT.
EXPECT VCTS IN MDT AND LNS...WITH SHOWERS AT JST. THE SHOWERS AND
JST SHOULD REDUCE CIGS AND VSBYS TO MVFR FOR A FEW HOURS...BEFORE
LIFTING NORTHWARD BY 09Z. ANY PRECIPITATION WILL REINFORCE LOW
LEVEL MOISTURE WHICH GIVEN THE CALMING WINDS...COULD ALLOW FOR
PATCHY FOG FROM 10Z THROUGH 14Z. AN APPROACHING COLD FRONT FROM
THE GREAT LAKES TODAY WILL ALLOW FOR A BETTER CHC FOR SHRA/TSRA.
THIS FRONT SHOULD PASS SOUTH OF THE REGION THURSDAY NIGHT...WITH
IMPROVING FLYING CONDS FOR FRI INTO THIS WEEKEND.
WITH VARYING TIMING...HAVE ONLY INCLUDED VCSH IN TAFS...BUT
REDUCTION IN CIG AND VSBYS WILL BE POSSIBLE.
OUTLOOK...
THU-THU NIGHT...MVFR POSSIBLE WITH SCT SHRA/TSRA.
FRI-MON...GENERALLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD/LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...FITZGERALD/LAMBERT
LONG TERM...LAMBERT/STEINBUGL
AVIATION...CERU/GARTNER
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
105 AM EDT THU AUG 22 2013
.SYNOPSIS...
AN UPPER LOW...NEAR MORGANTOWN WEST VIRGINIA...WILL DRIFT ACROSS THE
SOUTHERN TIER OF PENNSYLVANIA EARLY TODAY. WEAK RIDGING IN THE WAKE
OF THIS LOW WILL BE OVER THE REGION LATER THIS MORNING THROUGH THE
AFTERNOON HOURS...ACCOMPANIED BY GENERALLY FAIR WEATHER. A COLD
FRONT WILL PUSH SOUTHEAST ACROSS THE REGION LATE THURSDAY INTO EARLY
FRIDAY...FOLLOWED BY CANADIAN HIGH PRESSURE.
&&
.NEAR TERM /UNTIL 8 AM THIS MORNING/...
REGIONAL IR SATELLITE AND RADAR LOOP SHOWS A CLUSTER OF SHOWERS AND
LOW-TOPPED TSRA DEVELOPING INVOF THE LAUREL HIGHLANDS...SOUTH INTO
THE MTNS OF WVA AT 05Z...WITHIN A REGION OF MDTLY STRONG UPPER
DIFFLUENCE AND DIFFERENTIAL PVA JUST AHEAD OF A SLOW-MOVING UPPER
LOW.
LATEST HRRR SHOWS THIS AREA OF CONVECTION BLOSSOMING TO THE
NORTHEAST ACROSS THE SCENT MTNS THROUGH DAYBREAK...REACHING THE I-80
CORRIDOR THROUGH THE MIDDLE SUSQ VALLEY AROUND AND SHORTLY AFTER
SUNRISE. 04Z RUC ALSO SHOWING SIGNS OF THIS POTENTIAL DVLPMT AND
TRACK OF CONVECTION EARLY TODAY...BASED ON IT/S WELL-DEFINED CHANNEL
OF 925-850 MB THETA-E CONVERGENCE SETTING UP NEAR AND JUST TO THE SE
OF A KJST TO KUNV AND KIPT LINE. MID LEVEL LAPSE RATES ARE ALSO
STEEPENING IN THIS AREA THROUGH THE MORNING HOURS...AND CAN BE SEEN
IN THE MOST UNSTABLE AIR WITH CURRENT...MU CAPE OF 1200-1500 J/KG IN
THE REGION BETWEEN KJST...KAOO...KUNV...AND KFIG.
CONSIDERING ALL OF THESE NEAR TERM WEATHER FACTORS...WILL BE
BOOSTING POPS TO REFLECT A BLEND OF ALL HIGH RES/NEAR TERM MODEL
GUIDANCE...THOUGH QPF WILL BE SIGNIFICANTLY UNDER THE LOCALLY
EXCESSIVE CONVECTIVE AMOUNTS /OF 1-3 INCHES/ GENERATED BY THESE
MODELS.
A SECOND AREA OF HEAVIER CONVECTION SHOULD SLIDE OFF WELL TO THE
SOUTH OF YORK AND LANCASTER COUNTIES THROUGH THE MID MORNING...WITH
THE LOWER SUSQ VALLEY SEEING ISOLATED TO SCTD SHOWERS BETWEEN
07-12Z.
SFC DWPTS RANGE FROM THE U60S AND L70S IN THE SOUTH....TO THE UPPER
50S AND LOWER 60S IN THE NORTH...WHERE THE BLYR WILL LIKELY REMAIN
TOO DRY TO SUPPORT ANY CONVECTION.
EXTENSIVE CLOUD COVER AND LOW LVL MOISTURE WILL RESULT IN THE
WARMEST NIGHT/EARLY MORNING IN SOME TIME WITH LOWS RANGING FROM ARND
60F OVR THE N MTNS...TO ARND 70F ACROSS THE LOWER SUSQ VALLEY.
&&
.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM FRIDAY/...
REMNANTS OF UPPER LOW SHOULD TAKE UNTIL ARND MIDDAY TO CLEAR THE
SE COUNTIES...SO WILL CARRY A SLIGHT CHC OF A SHRA/TSRA DOWN THERE
UNTIL THAT TIME. RIDGING IN WAKE OF DEPARTING UPPER LOW SHOULD
BRING A PERIOD OF DRY CONDITIONS TO MOST OF CENTRAL PENN ON THURS
BEFORE COLD FRONT FROM THE GLAKES BRINGS ANOTHER THREAT OF
CONVECTION LATE IN THE DAY.
A RIBBON OF HIGHER PWATS BETWEEN 1.5 AND 1.75 INCHES AND SLIGHTLY
STEEPER MID-LEVEL LAPSE RATES SHOULD SUPPORT SCT SHRA/TSRA
DEVELOPING ACROSS THE NW MTNS THURSDAY AFTN AND SLIDING SE THRU
THE EVENING AND EARLY OVERNIGHT.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
OVERVIEW...THE LATEST MODEL AND ENSEMBLE GUIDANCE REMAINS IN VERY
GOOD AGREEMENT IN THE LARGE SCALE MEAN FLOW PATTERN CONSISTING OF
A BUILDING/STRONG UPPER RIDGE OVER THE PLAINS/MS VLY WITH TROUGHS
JUST OFF THE WEST AND EAST COASTS. HOWEVER...THE PCPN PATTERN OVER
THE LOCAL AREA WILL BE MODULATED BY SHORTWV IMPULSES DIVING ESEWD
DOWN THE NERN/FRONT SIDE OF THE RIDGE WITHIN A NWLY FLOW ALOFT.
THEREFORE DESPITE ABOVE AVG CONFIDENCE IN THE MEAN PATTERN...THE
SMALLER SCALE EMBEDDED SYSTEM TIMING AND LOCAL QPF/SENSIBLE WX
IMPACT IS MORE UNCERTAIN. AS SUCH...THE FINAL DAY 3-7 GRIDS WERE
DERIVED USING A CONSENSUS BLEND IN AN EFFORT TO MITIGATE THE LOWER
CONFIDENCE IN THE SFC DETAILS AND TO BEHOLD REASONABLE CONTINUITY
THE FCST.
HIGHLIGHTS...PUSH OF ABNORMALLY DRY AIR WITH BELOW NORMAL PWS
BEHIND THE THUR NGT FROPA APPEARS DELAYED BY ABOUT 6 HRS ON THE
12Z CYCLE...SUGGESTING A LOW CHC FOR SHOWERS ALONG THE SRN TIER
ZONES EARLY FRI. OTHERWISE...A MODIFIED CANADIAN HIGH PRESSURE
SYSTEM WILL DOMINATE THE PATTERN THROUGH THE WEEKEND..BRINGING
RELATIVELY COOL NIGHTS WITH VALLEY FOG AND COMFORTABLE HUMIDITY
DURING THE DAY. EXPECT A MORE UNSETTLED AND INCREASINGLY HUMID
PATTERN TO EVOLVE THRU THE FIRST PART OF NEXT WEEK..AS THE FOCUS
SHIFTS TO UPPER-LEVEL DISTURBANCES CRESTING THE PLAINS RIDGE AND
DIVING ESEWD THRU THE GREAT LAKES TAKING AIM ON THE NE STATES.
MODELS SUGGEST THIS ENERGY MAY TRIGGER ONE OR MORE ORGANIZED TSTM
COMPLEXES AS THEY ROLL DOWN THE FRONT-SIDE OF THE RIDGE.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
SHOWERS HAVE DIMINISHED GREATLY IN COVERAGE OVER THE LAST FEW
HOURS AND SHOULD GENERALLY BE DONE FOR THE NIGHT. IF ANY DO POP UP
THEY WILL BE OVER SRN PA...AT JST OR LNS TAF SITES. EXPECT AREAS OF
FOG/HAZE TO DEVELOP AS WELL...ALTHOUGH NOT AS THICK AS RECENT
NIGHTS WITH GREATER HGHT CLOUDS COVER KEEPING TEMPS FROM FALLING
OFF AS MUCH.
SLIGHTLY BETTER CHC FOR SHRA/TSRA STATEWIDE ON THURS AS A COLD
FRONT APPROACHES FROM THE GREAT LAKES. THIS FRONT SHOULD PASS
SOUTH OF THE REGION THURS NIGHT...WITH IMPROVING FLYING CONDS FOR
FRI INTO THIS WEEKEND.
OUTLOOK...
THU-THU NIGHT...MVFR POSSIBLE WITH SCT SHRA/TSRA.
FRI-MON...GENERALLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD/LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...FITZGERALD/EVANEGO
LONG TERM...STEINBUGL
AVIATION...GARTNER/EVANEGO
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1100 PM CDT WED AUG 21 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 323 PM CDT WED AUG 21 2013
MAIN FOCUS WILL BE ON THE FRONTAL PASSAGE TONIGHT AND THE
ASSOCIATED RAIN CHANCES.
COLD FRONT EXTENDS FROM NORTHERN WISCONSIN INTO NORTHEAST NEBRASKA
AT MID AFTERNOON. REGIONAL RADARS SHOW CONVECTIVE ACTIVITY ALONG
THE FRONT FROM NORTHERN WISCONSIN ACROSS MINNESOTA.
WATER VAPOR SATELLITE SHOWS THE MAIN SHORT WAVE TROUGH IS ALONG
THE CANADIAN BORDER MOVING INTO ONTARIO WITH A SECONDARY WAVE OVER
CENTRAL MINNESOTA. THE BEST PV ADVECTION IN THE 500-300 MB LAYER
WILL STAY TO THE NORTH OF THE AREA TONIGHT BUT THE EXPECTATION IS
THAT THE WAVE OVER MINNESOTA WILL PROVIDE JUST ENOUGH FORCING TO
HELP MAINTAIN THE CONVECTION ALONG THE FRONT AS IT COMES THROUGH.
ML CAPES AHEAD OF THE FRONT CURRENTLY ARE AROUND 3000 J/KG AND
WHILE THESE WILL DECREASE THROUGH THE EVENING WITH THE LOSS OF
HEATING...THE 21.18Z NAM INDICATES THESE WILL STAY AT OR ABOVE
1500 J/KG THROUGH THE EVENING AHEAD OF THE FRONT. THE BEST 0-6KM
SHEAR WILL REMAIN NORTH OF THE AREA CLOSER TO THE MAIN SHORT WAVE
TROUGH. HOWEVER...THE 0-3KM SHEAR WILL BE AROUND 30 KNOTS AND WILL
BE MORE THAN SUFFICIENT TO SUPPORT SOME SEVERE STORMS THROUGH THE
EVENING. LARGE HAIL AND DAMAGING WINDS STILL LOOK TO BE THE MAIN
THREATS. WILL BE INTERESTING TO SEE HOW THE CURRENT ACTIVITY
SOUTH OF THE TWIN CITIES EVOLVES THROUGH THE REMAINDER OF THE
AFTERNOON. THE 21.18Z RAP BUFKIT SOUNDINGS SUGGEST THE CAP IN
PLACE BETWEEN 750 AND 800 MB AT KRST WILL HOLD TIGHT UNTIL THE
FRONT MOVES THROUGH. IF THIS HAPPENS...THE ACTIVITY TO THE WEST
SHOULD DIMINISH AS IT MOVES IN AND THIS IS WHAT SEVERAL OF THE
SHORT RANGE MESO MODELS SUGGESTS. BASED ON THIS...HAVE TRIMMED
BACK THE RAIN CHANCES HEADING THROUGH THE EVENING ACROSS THE
WESTERN SECTIONS OF THE FORECAST AREA. FARTHER EAST...THE CAP IS
WEAKER AND IS EXPECTED TO ERODE AS THE FRONT MOVES IN...SO HAVE
MAINTAINED THE 60 TO 80 PERCENT CHANCES EAST OF THE MISSISSIPPI
RIVER.
ALL THE MODELS ALSO SUGGEST THE FRONT AND CONVECTION WILL MOVE
THROUGH PRETTY QUICK THIS EVENING TO THE POINT THAT MOST IF NOT
ALL OF THE FORECAST AREA SHOULD BE DRY BY 06Z. THUS SPED UP THE
FORECAST TO REFLECT THIS FASTER TIMING WITH JUST SOME 20 TO 40
PERCENT RAIN CHANCES ACROSS THE SOUTH FOR AFTER MIDNIGHT. HAVE
HELD ON TO SOME SMALL RAIN CHANCES ACROSS THE SOUTH FOR THURSDAY
MORNING. ALL THE MODELS INDICATE A CONVECTIVE COMPLEX WILL DEVELOP
ACROSS NEBRASKA THIS EVENING AND THEN MOVE EAST ALONG THE FRONT
TOWARD THE AREA OVERNIGHT WITH SOME SUGGESTIONS THAT THE NORTHERN
PART OF THE COMPLEX COULD SLIDE ACROSS THE SOUTHERN PARTS OF THE
AREA. OTHERWISE FOR THURSDAY...HIGH PRESSURE WILL MOVE IN FROM THE
NORTH WITH MUCH DRIER AIR SPREADING IN. NAM BUFKIT SOUNDING ACROSS
THE NORTHERN SECTIONS SHOW GOOD SUBSIDENCE OCCURRING AND WITH LOTS
OF DRY ALOFT TO MIX DOWN...DEW POINTS ARE EXPECTED TO DROP INTO
THE 40S FOR THE AFTERNOON. THIS HIGH WILL REMAIN THE DOMINANT
FEATURE FOR THE REMAINDER OF THE SHORT TERM HELPING TO KEEP
TEMPERATURES CLOSER TO NORMAL THROUGH FRIDAY WITH HIGHS IN THE
UPPER 70S TO LOWER 80S.
.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 323 PM CDT WED AUG 21 2013
CONSIDERABLE UNCERTAINTY IN THE EXTENDED IN REGARDS TO THE RAIN
CHANCES. THE UPPER LEVEL RIDGE WILL BE ANCHORED OVER THE CENTRAL
PART OF THE COUNTRY WITH ALL THE MODELS SHOWING SHORT WAVE TROUGHS
EXPECTED TO RIDE UP THE BACK SIDE AND OVER THE TOP OF THE RIDGE.
AT THE SURFACE...THE EXPECTATION IS THAT A WEAK SURFACE BOUNDARY
WILL APPROACH FROM THE WEST SATURDAY BUT STALL OUT AND BECOME
NEARLY STATIONARY BEFORE IT REACHES THE AREA. IT SHOULD THEN
WAFFLE NORTH/SOUTH AS SHORT WAVE TROUGHS MOVE AROUND THE RIDGE AND
CAUSE ROUNDS OF CONVECTION TO FORM. THE UNCERTAINTY COMES IN WHERE
THESE COMPLEXES WILL BE AND WHETHER THEY WILL IMPACT THE NORTHERN
PARTS OF THE FORECAST AREA OR NOT. AFTER THE INITIAL SHORT WAVE
TROUGH GOES BY SATURDAY WILL GENERALLY LIMIT THE RAIN CHANCES TO
THE I94 CORRIDOR FOR THE REMAINDER OF THE EXTENDED PERIOD AS THIS
AREA WILL BE CLOSEST TO THE FRONT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1100 PM CDT WED AUG 21 2013
A COLD FRONT WILL CONTINUE TO SLIDE SLOWLY SOUTHWARD
TONIGHT...GRADUALLY LAYING UP WEST TO EAST ACROSS CENTRAL IA.
MODELS POINTED TO A STORM COMPLEX DEVELOPING OVER NEB...AND RADAR
INDICATES IT HAS...AND IS MOVING EAST. LATEST HRRR/NAM12 ARE A LOT
MORE NORTH THAN MODEL RUNS OF THE PAST COUPLE DAYS. WHILE THE BULK
OF THE COMPLEX SHOULD STAY SOUTH...THERE COULD BE SOME SCATTERED
-SHRA THAT PASS ACROSS KRST/KLSE BETWEEN 12-15Z. WILL ADD A VCSH TO
ACCOUNT FOR THIS POTENTIAL. BELIEVE CIGS WILL STAY VFR.
MEANWHILE...MOIST SFC AIR LAGS BEHIND THE FRONT A BIT...WITH LATEST
RAP13 SUGGESTING DRIER AIR NOT WORKING INTO KRST/KLSE UNTIL AFTER
12Z. LIGHT SFC AND NEAR SFC WINDS FAVOR FOG FORMATION...ESPECIALLY
IN THE RIVER VALLEYS. RAIN OVER THE PAST FEW HOURS HELPS TOO. THINK
THIS WOULD BE A 1/4SM TYPE EVENT FOR KLSE...EXCEPT FOR THE
INCREASING CLOUDS/RAIN POTENTIAL FROM THE WEST. AS LONG AS THESE
ROLL IN AND STAY OVER KLSE...4-P6SM WOULD BE MORE LIKELY. SAME FOR
KRST. ALSO...THIS COULD PLAY OUT WITH FOG DEVELOPING EARLY...THEN
QUICKLY LIFTING INTO A SCT-BKN LOW STRATUS LAYER AS THE HIGH CLOUDS
MOVE IN. TRENDS WILL HAVE TO BE MONITORED CLOSELY OVERNIGHT.
HIGH PRESSURE BUILDS IN FROM SOUTHERN CANADA THU...AND PRESSURE
GRADIENT SLACKENS. COULD SEE SOME GUSTS IN THE MORNING...BUT LOW
LEVEL WINDS WEAKEN IN THE AFTERNOON. EXPECT VFR CONDITIONS WITH SOME
SCT-BKN HIGH CLOUDS. WITH HIGH PRESSURE WORKING OVER WI THU
NIGHT...FOG HAS TO BE CONSIDERED. AGAIN...CONDITIONS WOULD SEEM TO
LEAN TOWARD VALLEY FOG - IF IT DEVELOPS. AT THIS TIME...NAM BUFKIT
SOUNDINGS SUGGEST IT WOULD BE TOO BREEZY OFF THE SFC FOR A FG IMPACT
AT KLSE. THIS IS SUBJECT TO CHANGE OF COURSE. BR/FG POTENTIAL WILL
CONTINUE TO EVALUATED.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM....04
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS TUCSON AZ
845 AM MST THU AUG 22 2013
.SYNOPSIS...ISOLATED TO SCATTERED MOSTLY AFTERNOON AND EVENING
THUNDERSTORMS WILL PREVAIL THROUGH FRIDAY. THEREAFTER...INCREASING
MOISTURE FROM THE GULF OF CALIFORNIA WILL PROVIDE MORE COVERAGE OF
THUNDERSTORMS THIS WEEKEND. ABOVE NORMAL DAYTIME TEMPERATURES WILL
CONTINUE THROUGH FRIDAY FOLLOWED BY A COOLING TREND THIS WEEKEND.
&&
.DISCUSSION...IR/VISIBLE SATELLITE IMAGERY INDICATED CLOUDY SKIES
ACROSS WESTERN/CENTRAL PIMA COUNTY AND SOUTH CENTRAL PINAL COUNTY AT
THIS TIME. CLEAR SKIES TO MOSTLY CLEAR SKIES PREVAILED FROM TUCSON
EWD/SWD ACROSS GREENLEE/GRAHAM/COCHISE/SANTA CRUZ COUNTIES.
DEWPOINTS VALID 15Z RANGED GENERALLY FROM THE MID 50S-MID 60S...AND
THESE TEMPS WERE NEARLY IDENTICAL TO 24 HOURS AGO. SURFACE TEMPS
VALID 15Z WERE ABOUT 2-5 DEGS F WARMER VERSUS 24 HOURS AGO.
BLENDED TOTAL PRECIP WATER PRODUCT YIELDED VALUES RANGING FROM 1.10
INCHES NEAR THE NEW MEXICO BORDER TO 1.55 INCHES ACROSS WRN PIMA
COUNTY. 22/12Z KTWC SOUNDING PRECIP WATER VALUE OF 1.47 INCHES WAS
VIRTUALLY UNCHANGED VERSUS 24 HOURS AGO. HOWEVER...HAVE NOTED THE
MARKEDLY DRIER REGIME ABOVE 500 MB VERSUS WED MORNING. THE SOUNDING
SUPPORTS A MARGINALLY UNSTABLE ENVIRONMENT WITH MODIFIED CAPE AROUND
500 J/KG. 22/12Z UPPER AIR PLOTS INDICATED A BROAD RIDGE ACROSS MUCH
OF THE CONUS...AND A 576 DM LOW PRESSURE CENTERED NEAR SAN
FRANCISCO. LIGHT GENERALLY SELY FLOW ALOFT PREVAILED ACROSS SE AZ.
THE OFFICIAL FORECAST WAS UPDATED TO INSERT ISOLATED SHOWERS/TSTMS
THIS MORNING ACROSS WRN PIMA COUNTY AND SOUTH CENTRAL PINAL COUNTY.
OTHERWISE...APPEARS THAT THE FAVORED AREAS FOR SHOWERS/TSTMS THIS
AFTERNOON WILL BE MAINLY NEAR THE MOUNTAINS GIVEN THE VERY WEAK MID-
LEVEL STEERING FLOW. THE LATEST RUC HRRR THEN FAVORS LOCALES SOUTH
AND WEST OF TUCSON FROM LATE THIS AFTERNOON THRU THIS EVENING...
THEN ACROSS WRN/CENTRAL PIMA COUNTY LATE TONIGHT. THIS SCENARIO IS
VERY SIMILAR TO THE INHERITED OFFICIAL FORECAST. THUS...NO ADDITIONAL
GRIDDED DATA POP FIELD ADJUSTMENTS ARE ANTICIPATED AT THIS TIME.
HIGH TEMPS THIS AFTERNOON WILL GENERALLY BE A FEW DEGS ABOVE NORMAL.
PLEASE REFER TO THE PREVIOUS DISCUSSION SECTION BELOW FOR ADDITIONAL
DETAIL.
&&
.PREV DISCUSSION /154 AM MST THU AUG 22 2013/...MODELS INDICATE THAT
THE SWATH OF DRIER AIR WILL FILTER INTO THE REGION FROM THE EAST
TODAY...WHICH WILL HELP TO KEEP THUNDERSTORM ACTIVITY MOSTLY
ISOLATED IN NATURE THIS AFTERNOON AS WELL AS FRIDAY AFTERNOON.
HOWEVER...BY FRIDAY NIGHT INTO SATURDAY A SURGE OF MOISTURE UP THE
GULF OF CALIFORNIA WILL SPILL INTO SOUTHERN ARIZONA AS A WELL
ADVERTISED TROPICAL SYSTEM IS EXPECTED TO PARALLEL THE WEST COAST OF
BAJA THIS WEEKEND AND INTO EARLY NEXT WEEK. AS A RESULT OF THIS
INFLUX OF MOISTURE...EXPECT TO SEE AN INCREASE IN SHOWER AND
THUNDERSTORM ACTIVITY THIS WEEKEND. ONLY MADE MINOR ADJUSTMENTS TO
THE POP GRIDS FOR THIS TIME FRAME. FROM MONDAY ONWARD...SCATTERED
TYPE POPS EXPECTED FOR MOST LOCATIONS AS MOISTURE EXPECTED TO LINGER
THROUGH MID WEEK. HIGHS GENERALLY 2 TO 3 DEGS ABOVE NORMAL TODAY AND
FRIDAY...THEN 3 TO 5 DEGS BELOW NORMAL FOR THE WEEKEND.
THEREAFTER...HIGHS NEAR NORMAL. LOWS GENERALLY 2 TO 3 DEGS ABOVE
NORMAL EACH DAY.
&&
.AVIATION...VALID THRU 12Z 8/23...
AN UPPER LVL LOW ACROSS CENTRAL MEXICO WILL CONTINUE TO USHER IN DRY
MID LVL AIR INTO THE AREAS EAST OF KTUS. THIS WILL LIMIT TS
DEVELOPMENT THIS AFTERNOON...THOUGH ENOUGH MOISTURE AND INSTABILITY
IN PLACE FOR ISOLD DEVELOPMENT. THE MID LVL MOISTURE WILL REMAIN IN
PLACE FROM KOLS W-WARD RESULTING IN BETTER INSTABILITY AFTER 18Z.
WILL CONTINUE TO HANDLE THIS WITH VCSH AS TIMING AND COVERAGE
REMAINS UNCERTAIN. OTHERWISE...VFR CONDITIONS AND LIGHT DIURNAL
WINDS OUTSIDE OF TS OUTFLOW DRIVEN WINDS. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...EXPECT ISOLATED TO SCATTERED MAINLY AFTERNOON AND
EVENING THUNDERSTORMS THROUGH FRIDAY. MOISTURE WILL INCREASE THIS
WEEKEND FOR MORE WIDESPREAD COVERAGE OF SHOWERS AND THUNDERSTORMS.
THE DAILY CYCLE OF SCATTERED MAINLY AFTERNOON AND EVENING
THUNDERSTORMS WILL RETURN BY THE MIDDLE OF NEXT WEEK. OTHERWISE...
ABOVE NORMAL DAYTIME TEMPERATURES WILL OCCUR TODAY AND FRIDAY ALONG
WITH NORMAL DIURNAL WIND TRENDS. A COOLING TREND WILL OCCUR THIS
WEEKEND FOLLOWED BY GRADUALLY WARMER DAYTIME TEMPERATURES EARLY NEXT
WEEK.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
DISCUSSION/FIRE WEATHER...FRANCIS
PREVIOUS DISCUSSION...MOLLERE
AVIATION...MEADOWS
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1114 AM EDT THU AUG 22 2013
.SYNOPSIS...
A COLD FRONT APPROACHES FROM THE NORTHWEST THIS AFTERNOON...THEN MOVES
ACROSS THE REGION TONIGHT. HIGH PRESSURE BUILDS INTO THE TRI-
STATE BEHIND THE FRONT...THEN SETTLES TO THE SOUTH LATE THIS WEEKEND. A
SERIES OF TROUGHS WILL TRACK ACROSS THE REGION THROUGH THE MIDDLE
PORTION OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
PASSING 700-500 HPA SHORTWAVE COUPLED WITH PRE-FRONTAL SHRA
RESPONSIBLE FOR ONGOING SHRA/TSTM ACROSS THE TRI-STATE. HAVE
INCREASED POPS TO CATEGORICAL OVER NEXT FEW HOURS OVER MAINLY LONG
ISLAND BASED ON LATEST RADAR TRENDS.
STILL HAVE ANOTHER SHORTWAVE TO COME...SO HAVE CONTINUED WITH SCT
SHRA/TSTMS FOR THIS AFTERNOON. CAPES ON 12Z SOUNDINGS RANGED FROM
1000-2000 J/KG...BUT WITH FREEZING LEVELS OVER 14000 FT AND -20C
LEVEL AROUND 25000 FT IT IS A VERY WARM PROFILE - SO LOCALLY HEAVY
RAIN IS MAIN THREAT. SEE HYDROLOGY SECTION FOR DETAILS. GIVEN CAPE
CANNOT COMPLETELY RULE OUT LOCALLY STRONG TO SEVERE STORM -
ESPECIALLY OVER WESTERN ZONES IF THERE IS SOME SUN THIS AFTERNOON.
LATEST SATELLITE TRENDS MAKE IDEA OF EXTENSIVE BREAKS IN THE SUN
DOUBTFUL...AND BASED ON HOURLY TEMPERATURES CURRENTLY RUNNING
QUITE A BIT COOLER THAN FORECAST HAVE LOWERED HIGHS A FEW DEGREES
- CONSISTENT WITH A BLEND OF HRRR AND NAM 2-METER TEMPERATURES
WITH 12Z MET/6Z MAV AND LAV GUIDANCE.
THERE IS A MODERATE RISK OF RIP CURRENTS FROM SMITHS POINT BEACH
EAST TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
COLD FRONT MOVES ACROSS THE REGION FROM WEST TO EAST THROUGH
MIDNIGHT TONIGHT...AND THEN H5 TROUGH MOVES ACROSS THE REGION ON
FRIDAY. SHOWERS/TSTMS TAPER OFF FROM WEST TO EAST BY FRIDAY
MORNING...AND THEN DRYER AIR FILTERS INTO THE REGION AS HIGH PRES
BEGINS TO BUILD EAST AND SFC DEW POINTS DROP INTO THE MID/UPPER
50S.
LOWS TONIGHT WILL GENERALLY DROP INTO THE LOWER 70S IN/AROUND
NYC...AND INTO THE 60S ELSEWHERE. HIGHS ON FRIDAY WILL REACH THE
MID/UPPER 80S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
THIS TIME FRAME WILL FEATURE EXITING TROUGH OVER THE
NORTHEAST...WITH LARGE RIDGE BUILDING IN ACROSS THE MIDDLE OF THE
COUNTRY. BY EARLY NEXT WEEK...HEIGHTS LOWER ACROSS THE
NORTHEAST...WITH SUBTLE MODEL DIFFERENCES NOTED IN THE MEDIUM TO
LONG RANGE WITH REGARD TO EMBEDDED SHORTWAVES AND ASSOCIATED SFC
TROUGHS.
WILL THUS NOT STRAY TOO FAR FROM FORECAST...AND A DRY WEEKEND WILL
GIVE WAY TO UNSETTLED WEATHER EARLY TO MID WEEK NEXT WEEK. TIMING
OF ANY SCATTERED CONVECTION WILL BE EXTREMELY DIFFICULT TO DO THIS
FAR OUT.
OVERALL...NEAR NORMAL TEMPERATURES ARE ANTICIPATED THROUGH THIS
TIME FRAME FOR OUR LOCAL AREA...WITH THE HEAT REMAINING ACROSS THE
MIDDLE PORTION OF THE COUNTRY UNDERNEATH THE RIDGE.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
FIRST ROUND OF SHRA/TSRA HAS MOVED EAST OF THE AREA. WATCHING AN
AREA OF SHRA/TSRA OVER NORTHERN NJ. RIGHT NOW THINKING THAT THIS
WILL MOVE JUST WEST OF KEWR AND KTEB...SO ADDED VCTS FOR THESE
TERMINAL BETWEEN 1530-1630Z. CCFP HAS HIGH CONFIDENCE OF SPARSE
COVERAGE OVER THE CITY TERMINALS AT 19Z...SO ADDED TEMPO GROUP FOR
-TSRA FROM 18-21Z TODAY.
A TROUGH OF LOW PRESSURE WILL REMAIN OVER THE AREA TODAY AS A
COLD FRONT APPROACHES FROM THE WEST. THE FRONT WILL PUSH ACROSS
THE REGION TONIGHT INTO EARLY FRI MORNING...02Z-05Z AT KSWF TO
06Z-09Z AT KISP/KGON.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KJFK FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
KLGA FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
KTEB FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
KHPN FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
KISP FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
.THU NIGHT...PSBL MVFR TO LOCALLY IFR WITH ANY RESIDUAL
SHOWERS/TSTMS. COLD FROPA.
.FRI-MON...VFR.
&&
.MARINE...
THUNDERSTORMS LIKELY ACROSS LONG ISLAND SOUND AND POSSIBLE ACROSS
THE REMAINDER OF THE WATERS THROUGH THIS EVENING.
AN APPROACHING COLD FRONT THIS AFTERNOON....THAT CROSSES THE WATERS
TONIGHT COULD BRING SUSTAINED WINDS UP TO 15 KT GUSTS UP TO 20 KT
ON THE COASTAL OCEAN WATERS THROUGH TONIGHT. OTHERWISE...WINDS ARE
EXPECTED TO REMAIN 10 KT OR LESS OVER AREA WATERS THROUGH FRIDAY.
WITH THESE RELATIVELY LIGHT WINDS...SEAS ON THE COASTAL OCEAN
WATERS SHOULD REMAIN AT 3 FT OR LESS AND ON THE REMAINDER OF THE
WATERS 1 FT OR LESS THROUGH FRIDAY NIGHT AS WELL.
SUB SCA CONDITIONS ANTICIPATED FROM FRIDAY NIGHT INTO EARLY NEXT
WEEK.
&&
.HYDROLOGY...
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY THROUGH
TONIGHT. WITH PRECIPITABLE WATER VALUES OF 1 1/2 TO 2
INCHES...ANY THUNDERSTORMS THAT DO DEVELOP COULD PRODUCE LOCALLY
HEAVY RAIN...AND POSSIBLY MINOR FLOODING OF URBAN AND/OR POOR
DRAINAGE AREAS AS A RESULT. ISOLATED FLASH FLOODING...WHILE HIGHLY
UNLIKELY CANNOT BE COMPLETELY RULED OUT IF TRAINING OCCURS.
MAINLY DRY CONDITIONS ARE EXPECTED OVER THE WEEKEND. LOCAL HEAVY
RAIN WILL BE POSSIBLE WITH ANY SHOWERS AND THUNDERSTORMS NEXT
WEEK.
&&
.EQUIPMENT...
THE NOAA ALL HAZARDS WEATHER RADIO TRANSMITTER IN NEW YORK CITY
HAS BEEN REMOVED FROM SERVICE. TECHNICIANS CONTINUE TO WORK ON THE
SITUATION AND A TIME OF RETURN TO SERVICE IS UNKNOWN.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MPS/PW
NEAR TERM...MPS/PW
SHORT TERM...MPS
LONG TERM...PW
AVIATION...JP
MARINE...MPS/PW
HYDROLOGY...MPS/PW
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1012 AM EDT THU AUG 22 2013
.SYNOPSIS...
CONTINUED WARM AND MUGGY CONDITIONS AHEAD OF A SERIES OF WET
WEATHER DISTURBANCES TODAY INTO FRIDAY. SCATTERED SHOWERS AND
THUNDERSTORMS EXPECTED...CLEARING OUT BY AS LATE AS FRIDAY NIGHT.
THEREAFTER DRY AND NEAR SEASONABLE WEATHER WILL RETURN THIS
WEEKEND AS HIGH PRESSURE BUILDS ACROSS THE REGION. MORE HUMID
CONDITIONS AND PERIODS OF UNSETTLED WEATHER MOVES IN NEXT WEEK AS
A WARM FRONT MOVES INTO THE REGION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1015 AM UPDATE...
FOG OVER THE REGION CONTINUES TO LINGER AS SOUTHERLY FLOW
CONTINUES TO STREAM IN MOISTURE ALONG THE COASTS. OTHERWISE FOCUS
TURNS TO SCATTERED SHOWERS AND THUNDERSTORMS CURRENTLY OVER THE
NYC AND LONG ISLAND. THESE SHOWERS WILL SLOWLY MOVE ACROSS THE
SOUTHERN HALF OF THE REGION AS A GOOD AMOUNT OF DRY AIR IS IN
PLACE ACROSS THE NORTH. THIS IS INDICATED BY THE K INDEX AND 700MB
MOISTURE FIELDS. TRENDED THE NEAR TERM TOWARDS THE 12Z NAM AND
HRRR PARAMETERS AS THEY HAVE AN EXCELLENT HANDLE ON CURRENT RADAR
IMAGERY. BELIEVE PRECIP SHOULD BEGIN TO ENTER THE SOUTHERN
HARTFORD COUNTY WITHIN THE HOUR AND SLOWLY WILL MOVE TOWARDS THE
REGION BY THE AFTERNOON HOURS. EXPECT MAIN THREATS TO BE LIGHTNING
AND HEAVY RAINFALL AS PWAT VALUES ARE AROUND 1.5.
PREVIOUS DISCUSSION...
FOCUS WILL BE ON THE DEAMPLIFYING MID-LEVEL LOW PRESSURE TRACKING
EAST ACROSS THE DELMARVA OUT TO SEA. SQUEEZING UP AGAINST ATLANTIC
HIGH PRESSURE AND PUSHED BY A STRONGER SHORTWAVE AND TROUGH AXIS
APPROACHING FROM THE EASTERN GREAT LAKES WILL YIELD AMPLIFICATION
OF MID- TO UPPER-LEVEL TROPOSPHERIC WINDS PROMOTING GREATER
DIFFLUENCE ALOFT. IN RESPONSE...SHOULD SEE AN ENHANCEMENT OF
SOUTHERLY FLOW WITHIN THE LOW-LEVELS ADVECTING MORE MUGGY
CONDITIONS INTO SOUTHERN NEW ENGLAND AGAINST DRIER AIR /GUSTS UP
TO 20 MPH ALONG THE SOUTH COAST/. SUBSEQUENT MOISTENING TO THE
WET-BULB OF THE ATMOSPHERIC PROFILE SHOULD ALLOW THE BUILD UP OF
ELEVATED INSTABILITY.
FEEL ANY ACTIVITY TODAY WILL BE LOCALIZED MAINLY SOUTH AND WEST IN
REGIONS OF FAVORABLE LIFT ALOFT COLLOCATED WITH AREAS OF LOW-LEVEL
CONVERGENCE THAT CAPITALIZE ON THE GROWING INSTABILITY...ESPECIALLY
IF THE BOUNDARY LAYER HAS AN OPPORTUNITY TO DESTABILIZE. STILL
DIFFICULT TO PIN-POINT...BUT FEEL AREAS NORTH AND EAST MAY REMAIN
UNDER THE INFLUENCE OF DRIER AND SINKING AIR.
GREATER CONFIDENCE WITH THE LATEST HRRR AND 22.0Z NAM HIGHLIGHTING
SOME EARLY MORNING ACTIVITY COLLOCATED WITH THE NOSE OF A LOW-LEVEL
JET AXIS JUST ABOVE THE DECOUPLED BOUNDARY LAYER. ACTIVITY OCCURRING
ACROSS NORTHEAST PENNSYLVANIA SHOULD FOCUS EASTWARD WITH TIME. BUT
OTHERWISE...A MAJORITY OF THE FORECAST AREA MAY SIMPLY REMAIN PARTLY
CLOUDY AND DRY...ALLOWING HIGHS TO GET INTO THE MID- TO UPPER-80S...
WITH A FEW LOCATIONS AT OR ABOVE THE 90 DEGREE MARK FOR A SECOND DAY
IN A ROW.
CONSIDERING A WEAK SHEAR ENVIRONMENT WITH MODEST INSTABILITY ALONG
WITH NEAR-ZERO CORFIDI VECTORS AND A WEAK MEAN ATMOSPHERIC FLOW
AROUND 15 MPH...MAIN THREATS ASSOCIATED WITH ANY STORMS APPEAR TO
BE HEAVY RAIN AND POSSIBLE NUISANCE FLOODING /PWATS CONTINUE TO
RANGE AROUND 1.5 TO 1.75 INCHES/. COULD SEE SOME GUSTY WINDS
SHOULD THE BOUNDARY LAYER MIX-OUT WITH INVERTED-V PROFILES.
ACTIVITY ALONG THE UPSTREAM COLD FRONT WILL NOT PUSH INTO THE
FORECAST REGION UNTIL EVENING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
TONIGHT...
STRONGER SHORTWAVE AND TROUGH AXIS WITH ATTENDANT SURFACE COLD FRONT
WILL SWEEP THROUGH THE REGION REACHING SOUTHEAST MASSACHUSETTS BY
MORNING. ANTICIPATING SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF
THE COLD FRONT AIDED BY STRONG FRONTOGENETICAL LIFT. INITIALLY
PUSHING INTO WESTERN NEW ENGLAND BY EVENING...ACTIVITY LOOKS TO
DIMINISH EASTWARD TOWARDS BY MIDNIGHT INTO MORNING AS BETTER
DYNAMICS ALOFT LIFT NORTH AND EAST PARENT WITH THE MID-LEVEL LOW.
WITH A STABILIZING BOUNDARY LAYER PROFILE...FEEL ANY STORMS WILL BE
MAINLY ASSOCIATED WITH HEAVY RAIN. LESSER CONFIDENCE FOR NUISANCE
FLOODING AS THE BETTER PWAT ENVIRONMENT WILL BE WELL SOUTH AND EAST
OFFSHORE OF THE REGION. LOWS AROUND THE MID-60S.
FRIDAY...
SURFACE COLD FRONT SLOWS OFFSHORE...STALLING SOUTH OF SOUTHERN NEW
ENGLAND. CLOUDS AND SHOWERS WILL LINGER FOR THE FAR SOUTH-SOUTHEAST
PORTIONS OF THE FORECAST AREA. NORTHWEST FLOW PREVAILS PUSHING
COOLER AND DRIER AIR SOUTH WITHIN THE LOW- TO MID-LEVELS.
EXPECTING DEEP BOUNDARY LAYER MIXING UP TO H8 LENDING TO SCATTERED
TO BROKEN DIURNAL CUMULUS AND THE POSSIBILITY FOR SOME SPOTTY
SHOWERS CAPITALIZING ON THE LIFT OF MINOR ELEVATED INSTABILITY AHEAD
OF A REINFORCING SECONDARY COLD FRONT. WILL INSERT SLIGHT CHANCE
POPS FOR A MAJORITY OF THE FORECAST REGION FOR THE MIDDAY INTO
AFTERNOON PERIOD. WILL ALSO SEE THE MIX-DOWN OF DRIER AIR AND FASTER
MOMENTUM. WIND GUSTS AROUND 15 MPH EXPECTED WITH HIGHS AROUND THE
LOW-80S...COOLER ALONG THE SHORES AND HIGHER ELEVATIONS.
FRIDAY NIGHT...
REINFORCING COLD FRONT PUSHES WELL OFFSHORE PARENT WITH ANOTHER MID-
LEVEL TROUGH AXIS SWEEPING ACROSS NEW ENGLAND. WINDS BACK MORE
NORTHERLY CONTINUALLY ADVECTING MORE COOLER AND DRIER AIR SOUTHWARD
OUT OF CANADA. LOOKING AT A POTENTIALLY CHILLY NIGHT SHOULD
CONDITIONS REMAIN MOSTLY CLEAR. LOWS AROUND THE MID-50S.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
HIGHLIGHTS...
* DRY AND COOLER SAT...THEN WARMER SUNDAY
* BECOMING MORE HUMID NEXT WEEK WITH UNSETTLED WEATHER POSSIBLE FROM
TIME TO TIME.
OVERVIEW...
GUIDANCE IN GOOD AGREEMENT ON OVERALL PATTERN DURING THE EXTENDED
PERIOD. MID LEVEL TROF WHICH WILL BRING COOLER WEATHER TO START THE
WEEKEND WILL BE EXITING THE REGION BY SUNDAY. MODELS AGREE ON AN
ANOMALOUS AND EXPANSIVE MID LEVEL RIDGE BUILDING ACROSS THE CENTRAL
CONUS DURING MUCH OF THE PERIOD WITH SNE REMAINING ON THE SOUTHERN
EDGE OF THE POLAR JET WITH MAINLY NW FLOW ALOFT. THIS WILL KEEP THE
SIGNIFICANT HEAT WEST OF SNE AND ALSO MAKE US SUSCEPTIBLE TO
OCCASIONAL IMPULSES IN NW FLOW BEGINNING NEXT WEEK. THE TIMING AND
AMPLITUDE OF INDIVIDUAL SHORTWAVES WILL DETERMINE THE COVERAGE AND
INTENSITY OF SHOWERS AND THUNDERSTORMS...BUT THE THREAT WILL EXIST
SOMETIME FROM LATE MON INTO WED.
SATURDAY AND SUNDAY...
STRONG HIGH PRES BUILDS ACROSS SNE GRADUALLY SHIFTING TO THE S ON
SUNDAY. FOR SAT...NEARBY MID LEVEL TROF AND COLD POOL ACTING ON LOW
LEVEL MOISTURE WILL LIKELY BRING AT LEAST SCT-BKN CU BUT THE
MOISTURE IS SHALLOW SO DRY WEATHER EXPECTED. LESS CU ON SUNDAY AS
MID LEVEL TEMPS WARM. TEMPS WILL BE A FEW DEGREES BELOW NORMAL
SAT...MOSTLY IN THE MID/UPPER 70S THEN WARMING INTO UPPER 70S AND
LOWER 80S SUNDAY IN RESPONSE TO INCREASING MID LEVEL TEMPS.
MONDAY...
SOME DIFFERENCES BETWEEN GFS AND ECMWF BEGIN TO SHOW UP REGARDING
THE EASTWARD EXTENT OF THE WARM FRONT. GFS APPEARS TO MOVE THE WARM
FRONT THROUGH TOO QUICKLY. PREFER THE ECMWF KEEPING THE FRONT TO THE
WEST GIVEN THE NW FLOW ALOFT. MOST OF THE REGION SHOULD REMAIN DRY
ALTHOUGH CANT RULE OUT A FEW SHOWERS OR A THUNDERSTORM ACROSS W
ZONES LATE IN THE DAY AS MOISTURE INCREASES FROM THE WEST.
MONDAY NIGHT INTO WEDNESDAY...
IT APPEARS FRONTAL BOUNDARY MAY GET HUNG UP NEAR SNE DURING THIS
PERIOD. THIS WILL BRING THE THREAT OF SHOWERS AND THUNDERSTORMS FROM
TIME TO TIME BUT WE HAVE LOW CONFIDENCE IN TIMING AS THERE ARE
DIFFERENCES IN THE MODELS. HUMIDITY WILL BE INCREASING ALTHOUGH THE
HEAT WILL REMAIN TO THE WEST WITH TEMPS MOSTLY NEAR SEASONABLE
NORMALS.
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH FRIDAY NIGHT/...MODERATE CONFIDENCE.
AREAS OF MVFR/IFR FOG AND STRATUS WILL BURN OFF BY MID
MORNING. SHRA/TSRA WILL BE ON THE INCREASE FROM THE SOUTH AND
WEST BY LATE MORNING INTO THE AFTERNOON HOURS. MENTIONED VCSH FOR
NOW WITH OVERWHELMING UNCERTAINTY ON THE EVOLUTION AND POTENTIAL
IMPACTS OF SHRA/TSRA. SOUTHWEST WINDS PREVAILING WITH GUSTS UP TO
AROUND 20 KTS.
ACTIVITY CLEARS UP INTO FRIDAY MORNING WITH A COLD FRONT SWEEPING
ACROSS THE TERMINALS...WINDS BACKING WEST-NORTHWEST. MAY SEE A
SPOT SHRA/TSRA DURING THE DAY FRIDAY...BUT A REINFORCING COLD
FRONT WITH NORTH-NORTHWEST FLOW TO THE REAR SHOULD PUSH ALL
REMAINING ACTIVITY OFFSHORE.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. NO EXPECTATION FOR A SEA-
BREEZE.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF. SHRA/TSRA POSSIBLE BY THE
LATE MORNING HOURS.
OUTLOOK...SATURDAY THROUGH MONDAY...
HIGH CONFIDENCE. MOSTLY VFR WITH SCT-BKN DIURNAL CU. LATE
NIGHT/EARLY MORNING PATCHY MVFR/IFR FOG POSSIBLE IN THE CT VALLEY.
WIDELY SCT SHOWERS/TSTMS POSSIBLE WESTERN AREAS LATE MON.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH FRIDAY NIGHT/...MODERATE CONFIDENCE.
WINDS AND SEAS TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS. WORTHY
OF MENTION THAT SOUTHWEST WINDS WILL INCREASE WITH GUSTS UP TO 20
KTS POSSIBLE TODAY MAINLY ALONG THE SOUTH SHORE. SHOWERS AND
THUNDERSTORMS MAY BE ON THE INCREASE AHEAD OF A SURFACE COLD FRONT
ANTICIPATED TO SWEEP INTO THE WATERS CLOSER TO FRIDAY MORNING AND
CLEARING OUT BY FRIDAY LATE. BEHIND THE FRONT...WINDS WILL BACK
OUT OF THE NORTHWEST.
OUTLOOK...SATURDAY THROUGH MONDAY...
HIGH CONFIDENCE.
EXPECT WINDS AND SEAS TO REMAIN BELOW SCA THRESHOLDS FOR MOST OF THE
PERIOD. HOWEVER...SW WINDS COULD GUST TO 20+ KTS MON/MON NIGHT WITH
SEAS POSSIBLY BUILDING TO 5 FT OVER OUTER SOUTHERN WATERS.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KJC/SIPPRELL
NEAR TERM...DUNTEN/SIPPRELL
SHORT TERM...SIPPRELL
LONG TERM...KJC
AVIATION...KJC/SIPPRELL
MARINE...KJC/SIPPRELL
AREA FORECAST DISCUSSION
NWS TAUNTON MA
720 AM EDT THU AUG 22 2013
.SYNOPSIS...
CONTINUED WARM AND MUGGY CONDITIONS AHEAD OF A SERIES OF WET
WEATHER DISTURBANCES TODAY INTO FRIDAY. SCATTERED SHOWERS AND
THUNDERSTORMS EXPECTED...CLEARING OUT BY AS LATE AS FRIDAY NIGHT.
THEREAFTER DRY AND NEAR SEASONABLE WEATHER WILL RETURN THIS
WEEKEND AS HIGH PRESSURE BUILDS ACROSS THE REGION. MORE HUMID
CONDITIONS AND PERIODS OF UNSETTLED WEATHER MOVES IN NEXT WEEK AS
A WARM FRONT MOVES INTO THE REGION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
715 AM UPDATE...
WV IMAGERY SHOWS MID LEVEL SHORTWAVE MOVING SLOWLY EAST FROM WV.
AHEAD OF THIS IMPULSE...THERE WERE SCATTERED SHOWERS AND ISOLD
TSTMS FROM NE PA AND NJ TO SOUTH OF LI WHICH IS ALONG THE LEADING
EDGE OF THE KI GRADIENT. MODELS BRING THE HIGHER KI VALUES INTO
SNE LATER THIS MORNING INTO THE AFTERNOON AS THE SHORTWAVE
APPROACHES THE MID ATLC COAST. THIS WILL RESULT IN AN INCREASED
THREAT OF SHOWERS/TSTMS. CURRENT FORECAST POPS LOOK REASONABLE.
PATCHY FOG/STRATUS WILL BURN OFF BY MID MORNING.
PREVIOUS DISCUSSION...
FOCUS WILL BE ON THE DEAMPLIFYING MID-LEVEL LOW PRESSURE TRACKING
EAST ACROSS THE DELMARVA OUT TO SEA. SQUEEZING UP AGAINST ATLANTIC
HIGH PRESSURE AND PUSHED BY A STRONGER SHORTWAVE AND TROUGH AXIS
APPROACHING FROM THE EASTERN GREAT LAKES WILL YIELD AMPLIFICATION
OF MID- TO UPPER-LEVEL TROPOSPHERIC WINDS PROMOTING GREATER
DIFFLUENCE ALOFT. IN RESPONSE...SHOULD SEE AN ENHANCEMENT OF
SOUTHERLY FLOW WITHIN THE LOW-LEVELS ADVECTING MORE MUGGY
CONDITIONS INTO SOUTHERN NEW ENGLAND AGAINST DRIER AIR /GUSTS UP
TO 20 MPH ALONG THE SOUTH COAST/. SUBSEQUENT MOISTENING TO THE
WET-BULB OF THE ATMOSPHERIC PROFILE SHOULD ALLOW THE BUILD UP OF
ELEVATED INSTABILITY.
FEEL ANY ACTIVITY TODAY WILL BE LOCALIZED MAINLY SOUTH AND WEST IN
REGIONS OF FAVORABLE LIFT ALOFT COLLOCATED WITH AREAS OF LOW-LEVEL
CONVERGENCE THAT CAPITALIZE ON THE GROWING INSTABILITY...ESPECIALLY
IF THE BOUNDARY LAYER HAS AN OPPORTUNITY TO DESTABILIZE. STILL
DIFFICULT TO PIN-POINT...BUT FEEL AREAS NORTH AND EAST MAY REMAIN
UNDER THE INFLUENCE OF DRIER AND SINKING AIR.
GREATER CONFIDENCE WITH THE LATEST HRRR AND 22.0Z NAM HIGHLIGHTING
SOME EARLY MORNING ACTIVITY COLLOCATED WITH THE NOSE OF A LOW-LEVEL
JET AXIS JUST ABOVE THE DECOUPLED BOUNDARY LAYER. ACTIVITY OCCURRING
ACROSS NORTHEAST PENNSYLVANIA SHOULD FOCUS EASTWARD WITH TIME. BUT
OTHERWISE...A MAJORITY OF THE FORECAST AREA MAY SIMPLY REMAIN PARTLY
CLOUDY AND DRY...ALLOWING HIGHS TO GET INTO THE MID- TO UPPER-80S...
WITH A FEW LOCATIONS AT OR ABOVE THE 90 DEGREE MARK FOR A SECOND DAY
IN A ROW.
CONSIDERING A WEAK SHEAR ENVIRONMENT WITH MODEST INSTABILITY ALONG
WITH NEAR-ZERO CORFIDI VECTORS AND A WEAK MEAN ATMOSPHERIC FLOW
AROUND 15 MPH...MAIN THREATS ASSOCIATED WITH ANY STORMS APPEAR TO
BE HEAVY RAIN AND POSSIBLE NUISANCE FLOODING /PWATS CONTINUE TO
RANGE AROUND 1.5 TO 1.75 INCHES/. COULD SEE SOME GUSTY WINDS
SHOULD THE BOUNDARY LAYER MIX-OUT WITH INVERTED-V PROFILES.
ACTIVITY ALONG THE UPSTREAM COLD FRONT WILL NOT PUSH INTO THE
FORECAST REGION UNTIL EVENING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
TONIGHT...
STRONGER SHORTWAVE AND TROUGH AXIS WITH ATTENDANT SURFACE COLD FRONT
WILL SWEEP THROUGH THE REGION REACHING SOUTHEAST MASSACHUSETTS BY
MORNING. ANTICIPATING SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF
THE COLD FRONT AIDED BY STRONG FRONTOGENETICAL LIFT. INITIALLY
PUSHING INTO WESTERN NEW ENGLAND BY EVENING...ACTIVITY LOOKS TO
DIMINISH EASTWARD TOWARDS BY MIDNIGHT INTO MORNING AS BETTER
DYNAMICS ALOFT LIFT NORTH AND EAST PARENT WITH THE MID-LEVEL LOW.
WITH A STABILIZING BOUNDARY LAYER PROFILE...FEEL ANY STORMS WILL BE
MAINLY ASSOCIATED WITH HEAVY RAIN. LESSER CONFIDENCE FOR NUISANCE
FLOODING AS THE BETTER PWAT ENVIRONMENT WILL BE WELL SOUTH AND EAST
OFFSHORE OF THE REGION. LOWS AROUND THE MID-60S.
FRIDAY...
SURFACE COLD FRONT SLOWS OFFSHORE...STALLING SOUTH OF SOUTHERN NEW
ENGLAND. CLOUDS AND SHOWERS WILL LINGER FOR THE FAR SOUTH-SOUTHEAST
PORTIONS OF THE FORECAST AREA. NORTHWEST FLOW PREVAILS PUSHING
COOLER AND DRIER AIR SOUTH WITHIN THE LOW- TO MID-LEVELS.
EXPECTING DEEP BOUNDARY LAYER MIXING UP TO H8 LENDING TO SCATTERED
TO BROKEN DIURNAL CUMULUS AND THE POSSIBILITY FOR SOME SPOTTY
SHOWERS CAPITALIZING ON THE LIFT OF MINOR ELEVATED INSTABILITY AHEAD
OF A REINFORCING SECONDARY COLD FRONT. WILL INSERT SLIGHT CHANCE
POPS FOR A MAJORITY OF THE FORECAST REGION FOR THE MIDDAY INTO
AFTERNOON PERIOD. WILL ALSO SEE THE MIX-DOWN OF DRIER AIR AND FASTER
MOMENTUM. WIND GUSTS AROUND 15 MPH EXPECTED WITH HIGHS AROUND THE
LOW-80S...COOLER ALONG THE SHORES AND HIGHER ELEVATIONS.
FRIDAY NIGHT...
REINFORCING COLD FRONT PUSHES WELL OFFSHORE PARENT WITH ANOTHER MID-
LEVEL TROUGH AXIS SWEEPING ACROSS NEW ENGLAND. WINDS BACK MORE
NORTHERLY CONTINUALLY ADVECTING MORE COOLER AND DRIER AIR SOUTHWARD
OUT OF CANADA. LOOKING AT A POTENTIALLY CHILLY NIGHT SHOULD
CONDITIONS REMAIN MOSTLY CLEAR. LOWS AROUND THE MID-50S.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
HIGHLIGHTS...
* DRY AND COOLER SAT...THEN WARMER SUNDAY
* BECOMING MORE HUMID NEXT WEEK WITH UNSETTLED WEATHER POSSIBLE FROM
TIME TO TIME.
OVERVIEW...
GUIDANCE IN GOOD AGREEMENT ON OVERALL PATTERN DURING THE EXTENDED
PERIOD. MID LEVEL TROF WHICH WILL BRING COOLER WEATHER TO START THE
WEEKEND WILL BE EXITING THE REGION BY SUNDAY. MODELS AGREE ON AN
ANOMALOUS AND EXPANSIVE MID LEVEL RIDGE BUILDING ACROSS THE CENTRAL
CONUS DURING MUCH OF THE PERIOD WITH SNE REMAINING ON THE SOUTHERN
EDGE OF THE POLAR JET WITH MAINLY NW FLOW ALOFT. THIS WILL KEEP THE
SIGNIFICANT HEAT WEST OF SNE AND ALSO MAKE US SUSCEPTIBLE TO
OCCASIONAL IMPULSES IN NW FLOW BEGINNING NEXT WEEK. THE TIMING AND
AMPLITUDE OF INDIVIDUAL SHORTWAVES WILL DETERMINE THE COVERAGE AND
INTENSITY OF SHOWERS AND THUNDERSTORMS...BUT THE THREAT WILL EXIST
SOMETIME FROM LATE MON INTO WED.
SATURDAY AND SUNDAY...
STRONG HIGH PRES BUILDS ACROSS SNE GRADUALLY SHIFTING TO THE S ON
SUNDAY. FOR SAT...NEARBY MID LEVEL TROF AND COLD POOL ACTING ON LOW
LEVEL MOISTURE WILL LIKELY BRING AT LEAST SCT-BKN CU BUT THE
MOISTURE IS SHALLOW SO DRY WEATHER EXPECTED. LESS CU ON SUNDAY AS
MID LEVEL TEMPS WARM. TEMPS WILL BE A FEW DEGREES BELOW NORMAL
SAT...MOSTLY IN THE MID/UPPER 70S THEN WARMING INTO UPPER 70S AND
LOWER 80S SUNDAY IN RESPONSE TO INCREASING MID LEVEL TEMPS.
MONDAY...
SOME DIFFERENCES BETWEEN GFS AND ECMWF BEGIN TO SHOW UP REGARDING
THE EASTWARD EXTENT OF THE WARM FRONT. GFS APPEARS TO MOVE THE WARM
FRONT THROUGH TOO QUICKLY. PREFER THE ECMWF KEEPING THE FRONT TO THE
WEST GIVEN THE NW FLOW ALOFT. MOST OF THE REGION SHOULD REMAIN DRY
ALTHOUGH CANT RULE OUT A FEW SHOWERS OR A THUNDERSTORM ACROSS W
ZONES LATE IN THE DAY AS MOISTURE INCREASES FROM THE WEST.
MONDAY NIGHT INTO WEDNESDAY...
IT APPEARS FRONTAL BOUNDARY MAY GET HUNG UP NEAR SNE DURING THIS
PERIOD. THIS WILL BRING THE THREAT OF SHOWERS AND THUNDERSTORMS FROM
TIME TO TIME BUT WE HAVE LOW CONFIDENCE IN TIMING AS THERE ARE
DIFFERENCES IN THE MODELS. HUMIDITY WILL BE INCREASING ALTHOUGH THE
HEAT WILL REMAIN TO THE WEST WITH TEMPS MOSTLY NEAR SEASONABLE
NORMALS.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH FRIDAY NIGHT/...MODERATE CONFIDENCE.
AREAS OF MVFR/IFR FOG AND STRATUS WILL BURN OFF BY MID
MORNING...BUT MAY LINGER A FEW HOURS LATER AT ACK.
SHRA/TSRA WILL BE ON THE INCREASE FROM THE SOUTH AND WEST.
MENTIONED VCSH FOR NOW WITH OVERWHELMING UNCERTAINTY ON THE
EVOLUTION AND POTENTIAL IMPACTS OF SHRA/TSRA. SOUTHWEST WINDS
PREVAILING WITH GUSTS UP TO AROUND 20 KTS.
ACTIVITY CLEARS UP INTO FRIDAY MORNING WITH A COLD FRONT SWEEPING
ACROSS THE TERMINALS...WINDS BACKING WEST-NORTHWEST. MAY SEE A
SPOT SHRA/TSRA DURING THE DAY FRIDAY...BUT A REINFORCING COLD
FRONT WITH NORTH-NORTHWEST FLOW TO THE REAR SHOULD PUSH ALL
REMAINING ACTIVITY OFFSHORE.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. NO EXPECTATION FOR A SEA-
BREEZE.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF. SHRA/TSRA POSSIBLE BY THE
LATE MORNING HOURS.
OUTLOOK...SATURDAY THROUGH MONDAY...
HIGH CONFIDENCE. MOSTLY VFR WITH SCT-BKN DIURNAL CU. LATE
NIGHT/EARLY MORNING PATCHY MVFR/IFR FOG POSSIBLE IN THE CT VALLEY.
WIDELY SCT SHOWERS/TSTMS POSSIBLE WESTERN AREAS LATE MON.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH FRIDAY NIGHT/...MODERATE CONFIDENCE.
WINDS AND SEAS TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS. WORTHY
OF MENTION THAT SOUTHWEST WINDS WILL INCREASE WITH GUSTS UP TO 20
KTS POSSIBLE TODAY MAINLY ALONG THE SOUTH SHORE. SHOWERS AND
THUNDERSTORMS MAY BE ON THE INCREASE AHEAD OF A SURFACE COLD FRONT
ANTICIPATED TO SWEEP INTO THE WATERS CLOSER TO FRIDAY MORNING AND
CLEARING OUT BY FRIDAY LATE. BEHIND THE FRONT...WINDS WILL BACK
OUT OF THE NORTHWEST.
OUTLOOK...SATURDAY THROUGH MONDAY...
HIGH CONFIDENCE.
EXPECT WINDS AND SEAS TO REMAIN BELOW SCA THRESHOLDS FOR MOST OF THE
PERIOD. HOWEVER...SW WINDS COULD GUST TO 20+ KTS MON/MON NIGHT WITH
SEAS POSSIBLY BUILDING TO 5 FT OVER OUTER SOUTHERN WATERS.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KJC/SIPPRELL
NEAR TERM...KJC/SIPPRELL
SHORT TERM...SIPPRELL
LONG TERM...KJC
AVIATION...KJC/SIPPRELL
MARINE...KJC/SIPPRELL
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
1017 AM EDT Thu Aug 22 2013
.NEAR TERM [Through Today]...
The regional large scale pattern is highlighted by trough along NE
Conus from New England to mid-Atlc low, a ridge from Carolina coast
to Bermuda, a TUTT over Cntrl Gulf of Mex and low moving slowly west
off of Wrn Cuba. Local area remains in weakness between TUTT to our
SW and Atlc ridge centered to our NE. Satellite shows a fairly deep
plume of tropical air in between TUTT and Cuba low moving nwwd
across our area. PWATs remain above 2 inches. Looking nwd, we can see
swwd push of drier air beginning to impede from the NW.
At surface, 1022mb high pressure ridging from the Atlc Wwd across
the SE states with the axis just north of the forecast area. This
puts us in an E/SE low level flow regime making today`s sea breeze
climatology a hybrid of type 1 and 2 or more likely a disturbed
pattern (see below). However, main feature of interest is an MCS
that developed in tropical plume between TUTT and Cuba lows and
moved Nwwd generating strong to severe storms over local coastal
waters and adjacent coasts...mainly from Gulf to Franklin counties
after sunrise. However, there is some subsidence and warming temps
on the NW periphery This reflected well in HRRR. As a result,
forecast updated earlier to account for very high POPs over these
areas with sharp drop in pops S-N. Radar also shows some convection
already developing across Ern portions of S/Cntrl GA. HRRR and radar
shows some weakening of the MCS as it moves over land in next few
hours.
During the rest of today, the deep layer Atlc ridging will sink Swd
as shortwave push off mid-Atlc coast and the TUTT will weaken Wwd.
the MCS will continue to weaken and shift WNW. Assocd cloudiness and
warming temps may delay onset of seabreeze generated convection.
Main aftn and eve concern will be seabreeze-mesoscale boundary
clashes and HRRR shows main area of concern will be S/Cntrl GA. With
cooler temps expected aloft by late aftn, some storms may be strong
to isold severe especially where breaks in clouds occur. Strong wind
gusts will be the primary threat. Brief heavy downpours will be
possible in these storms. Will go with 70-80% POPs over wrn waters
and adjacent coast. Otherwise, 60-40% SW-NE Pop gradient. Morning
plus aftn clouds especially SW third of area will temper aftn highs
to mid 80s Walton county to low 90s ern most GA counties.
&&
.SHORT TERM [Tonight Through Saturday]...
Although much of the eastern part of the country will be under the
influence of mid/upper level short/long wave troughing, the local
area will remain south of the trough, under the influence of deep
layer ridging. The local weather pattern will be driven primarily
by typical seabreeze circulations, with the best chance for rain
across north Florida each afternoon. However, a punch of dry air
from the east may limit overall precip coverage across our SE Big
Bend counties on Thursday. Temperatures will remain near seasonal
levels.
&&
.LONG TERM [Saturday Night through Wednesday]...
The long term pattern through the middle part of next week should
trend towards drier/more typical summer weather for the most part.
We should see max temps in lower 90s for the most part.
&&
.Aviation...
[Through 12Z Friday] Isolated areas of dense fog and low CIGs should
start to burn off within in the next hour. A large cluster of
thunderstorms is currently located offshore, but expected to weaken
as it advances onshore. With the exception of VLD, where there are
ongoing TSRA, expect VCTS/TSRA beginning this afternoon at all
terminals and lasting til a couple hours after sunset. Will probably
see another round of low CIGs and visibilities tomorrow morning
before sunrise, but based purely on persistence, confidence is low
at this time except where it was included at ABY and VLD.
&&
.MARINE...
Winds and Seas will remain higher and gusty rest of today near any
stronger storms assocd with the MCS. Otherwise, a relatively weak
pressure pattern under the influence of surface high pressure will
result in winds and seas below headline levels through early next
week.
&&
.FIRE WEATHER...
No fire weather concerns are expected over the next week.
&&
.HYDROLOGY...
With many area rivers in flood stage, most have either crested or
are near crest as of this morning. The most notable rivers are the
Choctawhatchee, Chipola, and the Ochlockonee where levels have
reached moderate, or even major flood stage in the case of the
Choctawhatchee near Bruce. With a return to a more typical
precipitation pattern over the next couple of days, rivers should
see some relief allowing for declining levels through the weekend.
For more specific information on area rivers visit the following link:
http://water.weather.gov/ahps2/index.php?wfo=tae
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 92 73 92 71 93 / 50 30 40 30 40
Panama City 88 74 88 73 89 / 70 30 40 20 40
Dothan 90 71 91 71 93 / 40 30 30 30 30
Albany 92 72 92 71 93 / 40 20 20 20 30
Valdosta 93 72 93 70 91 / 50 20 20 20 40
Cross City 91 71 91 71 90 / 50 30 30 20 50
Apalachicola 89 74 87 72 89 / 70 30 30 30 30
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
NEAR TERM...Block
SHORT TERM...Harrigan
LONG TERM...Evans/Harrigan
AVIATION...Block/Navarro
MARINE...Block
FIRE WEATHER...Wool
HYDROLOGY...Harrigan
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
1005 AM EDT THU AUG 22 2013
.UPDATE...THE ATMOSPHERE REMAINS QUITE MOIST WITH PRECIPITABLE
WATER ON THE TBW SOUNDING AT 2.14 INCHES. THE WARMING SEEN IN THE
MID-LEVELS ON THIS MORNINGS 12Z TBW SOUNDING NEEDS SOME
DISCUSSION. THERE IS SOME SUBSIDENCE ON THE PERIPHERY OF THE MCS
OVER THE NORTHEAST GULF. THIS RESULTED IN SOME FAIRLY SIGNIFICANT
TEMPERATURE RISES ABOVE 600 MBS. AT FIRST GLANCE...THE SOUNDING
WOULD SEEM TO SUPPORT JUST YOUR MORE TYPICAL AFTERNOON STORMS WITH
GUSTY...BUT SUB-SEVERE WIND GUSTS. THE REALITY THOUGH IS THAT THE
MCS WILL WEAKEN AND MOVE AWAY FROM FLORIDA TODAY. MID-LEVEL
TEMPERATURES ARE LIKELY TO RETURN TO ABOUT WHERE THEY WERE
YESTERDAY...WITH THE 500 MB TEMPERATURE EXPECTED TO COOL BACK
TOWARD -8C BY 18Z. THE 500 MB TEMPERATURE AT CAPE CANAVERAL THIS
MORNING WAS -7.9C.
WITH THIS IN MIND...EXPECT ANOTHER ROUND OF STRONG TO SEVERE
THUNDERSTORMS THIS AFTERNOON. THE 11Z HRRR IS SHOWING AN INITIAL
BAND OF STORMS DROPPING SOUTHWESTWARD WITH AN OUTFLOW BOUNDARY
INTO THE NATURE COAST BY EARLY AFTERNOON...THEN THE EAST COAST SEA
BREEZE MOVES ACROSS AND INTERSECTS THE INITIAL CONVECTION. WHILE
ITS TOO EARLY TO PINPOINT WHERE THE STRONGEST STORMS WILL BE...IT
DOES LOOK LIKE MUCH OF OUR AREA WILL BE AFFECTED WITH THE BEST
CHANCES OVER THE INTERIOR DURING THE FIRST HALF OF THE AFTERNOON
THEN THE COASTAL AREAS DURING THE LATE AFTERNOON AND EVENING.
ONE THING TO WATCH FOR THAT IS NOT CURRENTLY REFLECTED IN OUR
FORECAST IS THE POTENTIAL FOR OUTFLOW BOUNDARIES COMING IN FROM
THE GULF AS THE MCS WEAKENS. THIS WOULD GREATLY ENHANCE THE LOW-
LEVEL CONVERGENCE AND UPDRAFT POTENTIAL THIS AFTERNOON.
FOR THE UPDATE...WILL RAISE RAIN CHANCES OVER THE INTERIOR INTO
THE LIKELY CATEGORY BETWEEN 2 AND 5 PM. I WILL ALSO ADD WORDING
FOR GUSTY WINDS IN THUNDERSTORMS THIS AFTERNOON.
THE UPDATES SHOULD BE OUT BY 1030 AM.
&&
.AVIATION...
EAST COAST SEA BREEZE WILL AGAIN PUSH WESTWARD PRODUCING
SCATTERED TO NUMEROUS AFTERNOON AND EARLY EVENING THUNDERSTORMS.
VCTS EXPECTED AT ALL TAF SITES BY 18Z WITH POTENTIAL 16Z
DEVELOPMENT OVER THE INTERIOR NEAR LAL. WILL TEMPO FOR TSRA AS
NECESSARY. VFR CONDITIONS WILL RETURN 0Z-2Z.
&&
.MARINE...
MCS OVER THE NORTHEAST GULF WILL CONTINUE TO WEAKEN AND MOVE AWAY.
WE COULD SEE BRIEF SEA BREEZES NEAR THE COAST...BUT FOR THE MOST
PART WE WILL SEE EAST TO SOUTHEAST FLOW OVER THE WATERS FOR THE
NEXT SEVERAL DAYS. TWEAKED THE WEATHER A BIT TO SHOW MORE
SCATTERED STORMS IN THE OFFSHORE WATERS THIS MORNING...BUT
OTHERWISE FEW CHANGES PLANNED.
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE/MARINE...JILLSON
AVIATION...BARRON
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
939 AM CDT THU AUG 22 2013
.DISCUSSION...
934 AM...MORNING UPDATE...INCREASED POPS FOR THE ENTIRE AREA
THROUGH EARLY/MID AFTERNOON. LARGE AREA OF SHOWERS WITH EMBEDDED
TSRA CONTINUES TO SLOWLY SAG SOUTH ACROSS THE SOUTHERN CWA.
CONVECTION OVER/ENTERING LASALLE COUNTY WILL HAVE THE HEAVIEST
RAINFALL RATES THAT MAY REACH 1 TO 2 INCHES PER HOUR IN SOME
LOCATIONS. OFF TO THE NORTHWEST...A LINE OF TSRA CONTINUES TO MOVE
EAST ACROSS SOUTHERN WI AND NORTHERN IL. WINDS GUSTED TO 43 KTS AT
KEFT JUST BEFORE THE TOP OF THE HOUR. WHILE STRONG WIND GUSTS WILL
REMAIN POSSIBLE ACROSS FAR NORTHERN IL...NOT ANTICIPATING ANY
WIDESPREAD SEVERE POTENTIAL. THIS COMPLEX IS ASSOCIATED WITH A
SHORTWAVE WHICH EVENTUALLY SLIDES SOUTHEAST ACROSS THE AREA LATE
THIS MORNING INTO EARLY THIS AFTERNOON...THUS EXPECT SHRA/TSRA TO
CONTINUE THROUGH EARLY/MID AFTERNOON AS IT SLIDES SOUTHEAST. HIGH
TEMPERATURES WILL LIKELY BE LOWER THAN CURRENTLY ADVERTISED AND
WILL NEED TO ADJUST THOSE SOON...THOUGH WITH SOME SUNSHINE BY LATE
AFTERNOON...ESPECIALLY ACROSS NORTHERN IL...COULD SEE SOME
RECOVERY BACK INTO THE LOWER 80S. CMS
//PREV DISCUSSION...
329 AM CDT
THE PRIMARY FORECAST CHALLENGES ARE CHANCES FOR STORMS TODAY AND
EARLY THIS EVE FOLLOWED BY THE HEAT...POTENTIALLY
PROLONGED...DURING NEXT WEEK.
THIS MORNING...A SOMEWHAT TRUBULENET...DISORGANIZED...AND EVEN
OVERTURNED ATMOSPHERE IS IN PLACE WITH ONE MCS HAVING GONE
THROUGH LATE LAST NIGHT ACROSS LAKE MI...WITH OUTFLOW STILL
PROGRESSING SOUTHEAST ACROSS THE CWA AS OF 315 AM. THIS IS
TRIGGERING A FEW STORMS THOUGH NOTHING ROBUST. FURTHER WEST AN MCS
EVOLVING EASTWARD ACROSS NORTHERN IA ALONG THE FRONTAL
BOUNDARY...WHICH IS VERY DIFFUSE EARLY TODAY...LOOKS TO WORK
EASTWARD WITHIN THE INSTABILITY MAXIMUM THROUGH THE MORNING. IN
ADVANCE OF THIS...NEAR THE BOUNDARY...THERE HAVE BEEN SOME
ISOLATED STORMS WITHIN THE HIGH PWAT AIR AND GENTLE WARM AIR
ADVECTION BUMPING UP AGAINST THE FRONT. SO ALL OF THIS LIKELY WILL
RESULT IN CONTINUED ISOLATED TO SCATTERED STORM GENERATION THIS
MORNING.
THIS AFTERNOON AND EVENING...WHILE THE IA MCS IS LIKELY TO BEGIN
DECAYING SOME LATER THIS MORNING GIVEN LIMITED DEEP LAYER
SHEAR...REMNANTS OF WHAT IS LEFT ALONG WITH A FORECAST
CONVECTIVELY ENHANCED WAVE BY THE RAP WILL MOVE INTO THE WESTERN
CWA LATE THIS MORNING/EARLY THIS AFTERNOON. THE POTENTIAL FOR THIS
TO RE-INSTIGATE STORMS IS CERTAINLY THERE WITH THE UNSTABLE AIR
MASS STILL IN PLACE AND NOT EXPECTED TO VACATE UNTIL THIS EVE DUE
TO THE SLOW COOL FRONTAL APPROACH FROM THE NORTH. MLCAPE VALUES
OF 1500-3000 J/KG ARE FORECAST BY THE NAM TO BUILD ACROSS THE
WESTERN AND SOUTHERN CWA...BASICALLY IN THOSE AREAS AWAY FROM THE
STABILIZING ONSHORE COMPONENT OFF THE LAKE. GIVEN LITTLE
INHIBITION THE TRIGGER OF THIS IMPULSE/MCV COULD BE ENOUGH TO
SPARK STORMS AND THE SUITE OF CONVECTIVE ALLOWING GUIDANCE HAS
MEMBERS THAT DO JUST THAT. SO HAVE INCREASED POPS SOME INCLUDING
HOLDING ONTO THEM LONGER. COULD CONCEIVABLY SEE SOME STORMS LINGER
INTO THE EVE...NAMELY SOUTH OF I-80. WITH LIMITED UPPER FORCING
AND DYNAMICS THE POTENTIAL FOR ORGANIZATION TOWARD ROBUST STORMS
REMAINS PRIMARILY LOW...THOUGH A FEW ISOLATED NEAR TO SEVERE
STORMS MAY DEVELOP. TEMPERATURES TODAY LOOK TO PEAK IN THE MID 80S
IN THOSE AREAS AWAY FROM THE LAKE WHERE AN ONSHORE COMPONENT WILL
INCREASE THIS AFTERNOON. HIGHS LAKESIDE LOOK TO BE IN THE UPPER
70S.
QUIET WEATHER IS EXPECTED FRI AND SAT WITH HIGHS AROUND NORMAL.
DEW POINTS IN THE 40S STILL LOOK PLAUSIBLE FRI AFTERNOON FOR
SEVERAL AREAS. FRI NIGHT LOOKS CLEAR AND CALM WITH HIGH
CONFIDENCE SO CONTINUE TO ADVERTISE LOWER TO MID 50S IN MOST
OUTLYING AREAS.
NEXT WEEK IS THE FINAL WEEK OF METEOROLOGICAL SUMMER AND IT IS
SHAPING UP TO BE EVERY BIT SUMMER...AT LEAST THE FIRST HALF OF
IT BUT POSSIBLY MUCH OF IT. WITH THE CURRENT TROUGH OVER CANADA
ONLY GIVING A GLANCING BLOW...THE RIDGE BUILDS BACK NORTHWARD
ACROSS THE CENTRAL TO EASTERN PARTS OF THE COUNTRY BY LATE IN THE
WEEKEND. DPROG/DTS FROM BOTH THE EC AND GFS HAVE INDICATED A
FURTHER NORTH 500MB RIDGE CENTER IN THE PAST 24 HOURS...AND THIS
HAS RESULTED IN A WARMING GUIDANCE TREND. THE 594DM RIDGE
PLACEMENT JUST TO THE WEST...MODEST AND WARM SW/WSW 850-925MB
FLOW...AND A DRY COLUMN IS A PATTERN CONDUCIVE FOR WIDESPREAD
LOWER-MID 90S MON AND TUE WITH THE 90 THRESHOLD LIKELY REACHED IN
PLACES ON SUN. THE JET IS ADVERTISED TO BE ACTIVE ON THE NORTH SIDE
OF THIS WITH BROAD LOW PRESSURE ACROSS THE HIGH PLAINS LIKELY
RESULTING IN MULTIPLE MCS DEVELOPMENT IF THIS PATTERN IS CORRECT.
AT THIS TIME...THESE ARE EXPECTED TO REMAIN NORTH BUT DEPENDING ON
FREQUENCY OF THEM LIKELY WILL DICTATE HOW FAR AND QUICKLY SOUTH
THE SURFACE BOUNDARY ADVANCES. WITH NO REAL DEW POINT SCOURING TO
OUR SOUTH FROM OUR CURRENT BOUNDARY...THESE SHOULD REBOUND TO AT
LEAST THE UPPER 60S BY MON AND HOLD TO SLIGHTLY INCREASE AS LONG
AS THE HEAT PERSISTS. BY TUE THIS RESULTS IN FORECAST HEAT INDICES
AT 100 TO 105 IN SOME PLACES /NOT CHICAGO AT THIS TIME/. WHILE
THIS PERIOD IS STILL NUMEROUS DAYS OUT...THERE SEEM TO BE A
LIMITED SET OF FACTORS PRIOR TO WED THAT COULD REALLY BOTCH UP THE
HEAT GIVEN THE AMPLITUDE OF THE RIDGE. WILL CONTINUE TO HIGHLIGHT
IN THE HWO.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* TIMING AND COVERAGE OF TSRA AT OR NEAR THE TERMINALS...WITH
ASSOCIATED CIG AND VSBY REDUCTIONS AND VARIABLE WINDS.
LENNING
//DISCUSSION...UPDATED 12Z...
A COUPLE AREAS OF CONCERN FOR SHOWERS AND/OR THUNDERSTORMS THROUGH
MID MORNING TODAY. CURRENTLY BOTH AREAS ARE WITHIN AN AREA OF
MODERATE INSTABILITY AHEAD OF A FRONT...ROUGHLY 1500 J/KG MUCAPE
THAT STRETCHES FROM NORTH CENTRAL IOWA ESE INTO NORTHERN ILLINOIS.
FIRST AREA IS IMMEDIATELY WEST OF THE CHICAGO TERMINALS STRETCHING
FROM ROUGHLY EFT THROUGH RFD AND NEAR JOT...ON THE NOSE OF VERY
MODEST MID LEVEL THETA E ADVECTION. MOST OF THIS AREA SHOULD SLIDE
SOUTH OF ORD BUT MAY GET NEAR MDW AS IT TRACKS SOUTHEAST DOWN THE
RIDGE AXIS THIS MORNING. OF CONCERN FOR ORD WILL BE THE NORTHERN
PORTION OF THIS LINE NEAR EFT THAT MAY TRACK NEAR THE TERMINAL
AROUND 13Z. FARTHER WEST...A SECOND AREA OF STRONG THUNDERSTORMS HAS
BEEN UNDERGOING A GRADUAL WEAKENING TREND AS IT MOVES AWAY FROM THE
BETTER MOISTURE TRANSPORT FROM THE LOW LEVEL JET FOCUSED OVER
EASTERN NEBRASKA AND WESTERN IOWA. A COUPLE NOTABLE CIRCULATIONS
EMBEDDED WITHIN THIS AREA ON RADAR IMAGERY...THE FIRST OF WHICH WILL
OVERTAKE THE FIRST LINE OF THUNDERSTORMS...MOVING NEAR OR JUST NORTH
OF RFD AROUND 14Z AND ORD BETWEEN 1530 AND 1600Z. OUT AHEAD OF THIS
FEATURE MAY BE THE MOST FAVORABLE PERIOD FOR THUNDERSTORMS. THAT
SAID THE FAVORABLE THETA E ADVECTION OVER THE AREA WILL HAVE SHIFTED
FARTHER EAST...WHICH SHOULD ALLOW THE GENERAL WEAKENING TREND TO
CONTINUE. THE IDEA FOR NOW IS FOR A SOME FESTERING SHOWERS TO MOVE
INTO THE CHICAGO AREA AROUND 13Z OR SO...THOUGH CANNOT RULE OUT SOME
ISOLATED LIGHTNING LINGERING THAT LATE INTO THE MORNING.
A COLD FRONT WHICH CURRENTLY STRETCHES FROM FAR NORTHERN LAKE
MICHIGAN WSW ACROSS CENTRAL WISCONSIN AND INTO SOUTHERN MINNESOTA
WILL CONTINUE TO SLOWLY SAG SOUTH THROUGH THE DAY. TIMING THE WIND
SHIFT MAY BECOME A BIT DIFFICULT DEPENDING ON THE EVOLUTION OF
THUNDERSTORMS THIS MORNING...BUT EXPECT THE FRONT TO PUSH THROUGH
THE AREA BETWEEN 14Z AND 16Z WITH WINDS SHIFTING TO NORTHERLY...THEN
NORTHEAST BEHIND. SOME MODELS SOUNDINGS INDICATE POTENTIALLY MVFR
CIGS BEHIND THE FRONT BUT MOS GUIDANCE CONTINUES TO HOLD OFF AND
DONT SEE MUCH INDICATION ON UPSTREAM OBS TO INCLUDE IN THE TAF.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* LOW TO MEDIUM CONIDENCE IN TIMING. ACTUALLY MAY NEED TO DELAY
TRENDS AT ORD BY A COUPLE HOURS...WITH ARRIVAL OF TSRA ACTIVITY
NOW MAYBE 17Z OR LATER.
* MEDIUM CONFIDENCE IN WIND...VSBY AND CIG IMPACTS.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT THROUGH WEDNESDAY...VFR.
BMD
&&
.MARINE...
250 AM CDT
LOW PRESSURE OF 29.1 INCHES LIES OVER FAR NORTHERN QUEBEC WITH A
COLD FRONT SAGGING TO THE SOUTHWEST ACROSS THE UPPER PENINSULA OF
MICHIGAN AND INTO CENTRAL WISCONSIN. THIS FRONT WILL CONTINUE TO
MOVE SOUTH ACROSS LAKE MICHIGAN THIS MORNING. THE FRONT SHOULD BE
SOUTH OF LAKE MICHIGAN THIS AFTERNOON AS HIGH PRESSURE OF 30.2
INCHES BUILDS ACROSS THE UPPER MIDWEST. THE HIGH WILL SHIFT EAST
OVER LAKE MICHIGAN ON FRIDAY...THEN OVER THE EASTERN LAKES
SATURDAY. A BROAD AREA OF LOW PRESSURE AVERAGING 29.7 INCHES WILL
DEVELOP OVER THE NORTHERN PLAINS AND CANADIAN PRAIRIES SUNDAY AND
MONDAY...AND SLOWLY SHIFT EAST ACROSS THE GREAT LAKES THROUGH
MIDWEEK.
BMD
&&
.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:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
934 AM CDT THU AUG 22 2013
.DISCUSSION...
934 AM...MORNING UPDATE...INCREASED POPS FOR THE ENTIRE AREA
THROUGH EARLY/MID AFTERNOON. LARGE AREA OF SHOWERS WITH EMBEDDED
TSRA CONTINUES TO SLOWLY SAG SOUTH ACROSS THE SOUTHERN CWA.
CONVECTION OVER/ENTERING LASALLE COUNTY WILL HAVE THE HEAVIEST
RAINFALL RATES THAT MAY REACH 1 TO 2 INCHES PER HOUR IN SOME
LOCATIONS. OFF TO THE NORTHWEST...A LINE OF TSRA CONTINUES TO MOVE
EAST ACROSS SOUTHERN WI AND NORTHERN IL. WINDS GUSTED TO 43 KTS AT
KEFT JUST BEFORE THE TOP OF THE HOUR. WHILE STRONG WIND GUSTS WILL
REMAIN POSSIBLE ACROSS FAR NORTHERN IL...NOT ANTICIPATING ANY
WIDESPREAD SEVERE POTENTIAL. THIS COMPLEX IS ASSOCIATED WITH A
SHORTWAVE WHICH EVENTUALLY SLIDES SOUTHEAST ACROSS THE AREA LATE
THIS MORNING INTO EARLY THIS AFTERNOON...THUS EXPECT SHRA/TSRA TO
CONTINUE THROUGH EARLY/MID AFTERNOON AS IT SLIDES SOUTHEAST. HIGH
TEMPERATURES WILL LIKELY BE LOWER THAN CURRENTLY ADVERTISED AND
WILL NEED TO ADJUST THOSE SOON...THOUGH WITH SOME SUNSHINE BY LATE
AFTERNOON...ESPECIALLY ACROSS NORTHERN IL...COULD SEE SOME
RECOVERY BACK INTO THE LOWER 80S. CMS
//PREV DISCUSSION...
329 AM CDT
THE PRIMARY FORECAST CHALLENGES ARE CHANCES FOR STORMS TODAY AND
EARLY THIS EVE FOLLOWED BY THE HEAT...POTENTIALLY
PROLONGED...DURING NEXT WEEK.
THIS MORNING...A SOMEWHAT TRUBULENET...DISORGANIZED...AND EVEN
OVERTURNED ATMOSPHERE IS IN PLACE WITH ONE MCS HAVING GONE
THROUGH LATE LAST NIGHT ACROSS LAKE MI...WITH OUTFLOW STILL
PROGRESSING SOUTHEAST ACROSS THE CWA AS OF 315 AM. THIS IS
TRIGGERING A FEW STORMS THOUGH NOTHING ROBUST. FURTHER WEST AN MCS
EVOLVING EASTWARD ACROSS NORTHERN IA ALONG THE FRONTAL
BOUNDARY...WHICH IS VERY DIFFUSE EARLY TODAY...LOOKS TO WORK
EASTWARD WITHIN THE INSTABILITY MAXIMUM THROUGH THE MORNING. IN
ADVANCE OF THIS...NEAR THE BOUNDARY...THERE HAVE BEEN SOME
ISOLATED STORMS WITHIN THE HIGH PWAT AIR AND GENTLE WARM AIR
ADVECTION BUMPING UP AGAINST THE FRONT. SO ALL OF THIS LIKELY WILL
RESULT IN CONTINUED ISOLATED TO SCATTERED STORM GENERATION THIS
MORNING.
THIS AFTERNOON AND EVENING...WHILE THE IA MCS IS LIKELY TO BEGIN
DECAYING SOME LATER THIS MORNING GIVEN LIMITED DEEP LAYER
SHEAR...REMNANTS OF WHAT IS LEFT ALONG WITH A FORECAST
CONVECTIVELY ENHANCED WAVE BY THE RAP WILL MOVE INTO THE WESTERN
CWA LATE THIS MORNING/EARLY THIS AFTERNOON. THE POTENTIAL FOR THIS
TO RE-INSTIGATE STORMS IS CERTAINLY THERE WITH THE UNSTABLE AIR
MASS STILL IN PLACE AND NOT EXPECTED TO VACATE UNTIL THIS EVE DUE
TO THE SLOW COOL FRONTAL APPROACH FROM THE NORTH. MLCAPE VALUES
OF 1500-3000 J/KG ARE FORECAST BY THE NAM TO BUILD ACROSS THE
WESTERN AND SOUTHERN CWA...BASICALLY IN THOSE AREAS AWAY FROM THE
STABILIZING ONSHORE COMPONENT OFF THE LAKE. GIVEN LITTLE
INHIBITION THE TRIGGER OF THIS IMPULSE/MCV COULD BE ENOUGH TO
SPARK STORMS AND THE SUITE OF CONVECTIVE ALLOWING GUIDANCE HAS
MEMBERS THAT DO JUST THAT. SO HAVE INCREASED POPS SOME INCLUDING
HOLDING ONTO THEM LONGER. COULD CONCEIVABLY SEE SOME STORMS LINGER
INTO THE EVE...NAMELY SOUTH OF I-80. WITH LIMITED UPPER FORCING
AND DYNAMICS THE POTENTIAL FOR ORGANIZATION TOWARD ROBUST STORMS
REMAINS PRIMARILY LOW...THOUGH A FEW ISOLATED NEAR TO SEVERE
STORMS MAY DEVELOP. TEMPERATURES TODAY LOOK TO PEAK IN THE MID 80S
IN THOSE AREAS AWAY FROM THE LAKE WHERE AN ONSHORE COMPONENT WILL
INCREASE THIS AFTERNOON. HIGHS LAKESIDE LOOK TO BE IN THE UPPER
70S.
QUIET WEATHER IS EXPECTED FRI AND SAT WITH HIGHS AROUND NORMAL.
DEW POINTS IN THE 40S STILL LOOK PLAUSIBLE FRI AFTERNOON FOR
SEVERAL AREAS. FRI NIGHT LOOKS CLEAR AND CALM WITH HIGH
CONFIDENCE SO CONTINUE TO ADVERTISE LOWER TO MID 50S IN MOST
OUTLYING AREAS.
NEXT WEEK IS THE FINAL WEEK OF METEOROLOGICAL SUMMER AND IT IS
SHAPING UP TO BE EVERY BIT SUMMER...AT LEAST THE FIRST HALF OF
IT BUT POSSIBLY MUCH OF IT. WITH THE CURRENT TROUGH OVER CANADA
ONLY GIVING A GLANCING BLOW...THE RIDGE BUILDS BACK NORTHWARD
ACROSS THE CENTRAL TO EASTERN PARTS OF THE COUNTRY BY LATE IN THE
WEEKEND. DPROG/DTS FROM BOTH THE EC AND GFS HAVE INDICATED A
FURTHER NORTH 500MB RIDGE CENTER IN THE PAST 24 HOURS...AND THIS
HAS RESULTED IN A WARMING GUIDANCE TREND. THE 594DM RIDGE
PLACEMENT JUST TO THE WEST...MODEST AND WARM SW/WSW 850-925MB
FLOW...AND A DRY COLUMN IS A PATTERN CONDUCIVE FOR WIDESPREAD
LOWER-MID 90S MON AND TUE WITH THE 90 THRESHOLD LIKELY REACHED IN
PLACES ON SUN. THE JET IS ADVERTISED TO BE ACTIVE ON THE NORTH SIDE
OF THIS WITH BROAD LOW PRESSURE ACROSS THE HIGH PLAINS LIKELY
RESULTING IN MULTIPLE MCS DEVELOPMENT IF THIS PATTERN IS CORRECT.
AT THIS TIME...THESE ARE EXPECTED TO REMAIN NORTH BUT DEPENDING ON
FREQUENCY OF THEM LIKELY WILL DICTATE HOW FAR AND QUICKLY SOUTH
THE SURFACE BOUNDARY ADVANCES. WITH NO REAL DEW POINT SCOURING TO
OUR SOUTH FROM OUR CURRENT BOUNDARY...THESE SHOULD REBOUND TO AT
LEAST THE UPPER 60S BY MON AND HOLD TO SLIGHTLY INCREASE AS LONG
AS THE HEAT PERSISTS. BY TUE THIS RESULTS IN FORECAST HEAT INDICES
AT 100 TO 105 IN SOME PLACES /NOT CHICAGO AT THIS TIME/. WHILE
THIS PERIOD IS STILL NUMEROUS DAYS OUT...THERE SEEM TO BE A
LIMITED SET OF FACTORS PRIOR TO WED THAT COULD REALLY BOTCH UP THE
HEAT GIVEN THE AMPLITUDE OF THE RIDGE. WILL CONTINUE TO HIGHLIGHT
IN THE HWO.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* A COUPLE ROUNDS OF THUNDERSTORMS MOVING ACROSS THE AREA THIS
MORNING.
* WIND SHIFT TO THE NORTH AND NORTHEAST WITH FROPA MID TO LATE
MORNING.
* POTENTIAL FOR MVFR CIGS BEHIND FRONT.
BMD
//DISCUSSION...UPDATED 12Z...
A COUPLE AREAS OF CONCERN FOR SHOWERS AND/OR THUNDERSTORMS THROUGH
MID MORNING TODAY. CURRENTLY BOTH AREAS ARE WITHIN AN AREA OF
MODERATE INSTABILITY AHEAD OF A FRONT...ROUGHLY 1500 J/KG MUCAPE
THAT STRETCHES FROM NORTH CENTRAL IOWA ESE INTO NORTHERN ILLINOIS.
FIRST AREA IS IMMEDIATELY WEST OF THE CHICAGO TERMINALS STRETCHING
FROM ROUGHLY EFT THROUGH RFD AND NEAR JOT...ON THE NOSE OF VERY
MODEST MID LEVEL THETA E ADVECTION. MOST OF THIS AREA SHOULD SLIDE
SOUTH OF ORD BUT MAY GET NEAR MDW AS IT TRACKS SOUTHEAST DOWN THE
RIDGE AXIS THIS MORNING. OF CONCERN FOR ORD WILL BE THE NORTHERN
PORTION OF THIS LINE NEAR EFT THAT MAY TRACK NEAR THE TERMINAL
AROUND 13Z. FARTHER WEST...A SECOND AREA OF STRONG THUNDERSTORMS HAS
BEEN UNDERGOING A GRADUAL WEAKENING TREND AS IT MOVES AWAY FROM THE
BETTER MOISTURE TRANSPORT FROM THE LOW LEVEL JET FOCUSED OVER
EASTERN NEBRASKA AND WESTERN IOWA. A COUPLE NOTABLE CIRCULATIONS
EMBEDDED WITHIN THIS AREA ON RADAR IMAGERY...THE FIRST OF WHICH WILL
OVERTAKE THE FIRST LINE OF THUNDERSTORMS...MOVING NEAR OR JUST NORTH
OF RFD AROUND 14Z AND ORD BETWEEN 1530 AND 1600Z. OUT AHEAD OF THIS
FEATURE MAY BE THE MOST FAVORABLE PERIOD FOR THUNDERSTORMS. THAT
SAID THE FAVORABLE THETA E ADVECTION OVER THE AREA WILL HAVE SHIFTED
FARTHER EAST...WHICH SHOULD ALLOW THE GENERAL WEAKENING TREND TO
CONTINUE. THE IDEA FOR NOW IS FOR A SOME FESTERING SHOWERS TO MOVE
INTO THE CHICAGO AREA AROUND 13Z OR SO...THOUGH CANNOT RULE OUT SOME
ISOLATED LIGHTNING LINGERING THAT LATE INTO THE MORNING.
A COLD FRONT WHICH CURRENTLY STRETCHES FROM FAR NORTHERN LAKE
MICHIGAN WSW ACROSS CENTRAL WISCONSIN AND INTO SOUTHERN MINNESOTA
WILL CONTINUE TO SLOWLY SAG SOUTH THROUGH THE DAY. TIMING THE WIND
SHIFT MAY BECOME A BIT DIFFICULT DEPENDING ON THE EVOLUTION OF
THUNDERSTORMS THIS MORNING...BUT EXPECT THE FRONT TO PUSH THROUGH
THE AREA BETWEEN 14Z AND 16Z WITH WINDS SHIFTING TO NORTHERLY...THEN
NORTHEAST BEHIND. SOME MODELS SOUNDINGS INDICATE POTENTIALLY MVFR
CIGS BEHIND THE FRONT BUT MOS GUIDANCE CONTINUES TO HOLD OFF AND
DONT SEE MUCH INDICATION ON UPSTREAM OBS TO INCLUDE IN THE TAF.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM CONFIDENCE IN TSRA IMPACTING THE TERMINALS AND TIMING.
* MEDIUM CONFIDENCE IN WIND TRENDS/TIMING SHIFT.
* LOW CONFIDENCE IN MVFR CIGS.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT THROUGH WEDNESDAY...VFR.
BMD
&&
.MARINE...
250 AM CDT
LOW PRESSURE OF 29.1 INCHES LIES OVER FAR NORTHERN QUEBEC WITH A
COLD FRONT SAGGING TO THE SOUTHWEST ACROSS THE UPPER PENINSULA OF
MICHIGAN AND INTO CENTRAL WISCONSIN. THIS FRONT WILL CONTINUE TO
MOVE SOUTH ACROSS LAKE MICHIGAN THIS MORNING. THE FRONT SHOULD BE
SOUTH OF LAKE MICHIGAN THIS AFTERNOON AS HIGH PRESSURE OF 30.2
INCHES BUILDS ACROSS THE UPPER MIDWEST. THE HIGH WILL SHIFT EAST
OVER LAKE MICHIGAN ON FRIDAY...THEN OVER THE EASTERN LAKES
SATURDAY. A BROAD AREA OF LOW PRESSURE AVERAGING 29.7 INCHES WILL
DEVELOP OVER THE NORTHERN PLAINS AND CANADIAN PRAIRIES SUNDAY AND
MONDAY...AND SLOWLY SHIFT EAST ACROSS THE GREAT LAKES THROUGH
MIDWEEK.
BMD
&&
.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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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
647 AM CDT THU AUG 22 2013
.DISCUSSION...
630 AM CDT
HAVE INCREASED POPS THROUGH THIS MORNING WITH OBSERVATIONAL AND
ENVIRONMENTAL ANALYSIS TRENDS ALL SUPPORTING CONVECTIVE LONGEVITY
IN THE AREA. THE ARC OF STORMS EARLY THIS MORNING FROM ROCKFORD
SOUTHEASTWARD LOOKS TO BE ROOTED ON AN ELEVATED AREA OF ISENTROPIC
ASCENT AND FOCUS ON SOME FORM OF ELEVATED CONVERGENCE. ONE OF
THESE STORMS PUT DOWN A QUICK TWO PLUS INCHES IN ROCHELLE. THE
HIGH PWAT AIR AND DEEP INSTABILITY ALONG WITH LITTLE IN THE WAY OF
SHEAR WILL CONTINUE TO MAKE THESE A MAINLY LOCALIZED HEAVY RAIN
THREAT. FURTHER WEST AN ORGANIZED AREA OF CONVECTION IS
PROGRESSING EAST ACROSS NORTHEAST IA. WHILE THIS IS SHOWING A
SLIGHT DIMINISHING TREND IN LIGHTING AND SOMEWHAT IN
STRUCTURE...THIS IS BEING DRIVEN BY AN MCV AND LIKELY WILL
OVERCOME THE CURRENT CONVECTION IN NORTH CENTRAL IL. TOGETHER
THESE AREAS WILL PROVIDE WIDESPREAD ENOUGH CONVECTION FROM
ROCKFORD THROUGH THE WESTERN METRO TO WARRANT HIGHER POPS AND QPF.
THE SEVERE WEATHER THREAT STILL REMAINS LIMITED AND REGIONALLY
THERE HAVE NOT BEEN ANY STORMS TO APPROACH SEVERE LIMITS. HOWEVER
THE EARLIER STORM IN ROCHELLE DID HAVE 39 MPH AND ANY CLUSTERS OF
CONVECTION WILL LIKELY HAVE TEMPORARY GUSTS AT OR ABOVE THAT GIVEN
SOME POSSIBLE WATER LOADING AND HIGH DCAPE AIR.
MTF
//PREV DISCUSSION...
329 AM CDT
THE PRIMARY FORECAST CHALLENGES ARE CHANCES FOR STORMS TODAY AND
EARLY THIS EVE FOLLOWED BY THE HEAT...POTENTIALLY
PROLONGED...DURING NEXT WEEK.
THIS MORNING...A SOMEWHAT TRUBULENET...DISORGANIZED...AND EVEN
OVERTURNED ATMOSPHERE IS IN PLACE WITH ONE MCS HAVING GONE
THROUGH LATE LAST NIGHT ACROSS LAKE MI...WITH OUTFLOW STILL
PROGRESSING SOUTHEAST ACROSS THE CWA AS OF 315 AM. THIS IS
TRIGGERING A FEW STORMS THOUGH NOTHING ROBUST. FURTHER WEST AN MCS
EVOLVING EASTWARD ACROSS NORTHERN IA ALONG THE FRONTAL
BOUNDARY...WHICH IS VERY DIFFUSE EARLY TODAY...LOOKS TO WORK
EASTWARD WITHIN THE INSTABILITY MAXIMUM THROUGH THE MORNING. IN
ADVANCE OF THIS...NEAR THE BOUNDARY...THERE HAVE BEEN SOME
ISOLATED STORMS WITHIN THE HIGH PWAT AIR AND GENTLE WARM AIR
ADVECTION BUMPING UP AGAINST THE FRONT. SO ALL OF THIS LIKELY WILL
RESULT IN CONTINUED ISOLATED TO SCATTERED STORM GENERATION THIS
MORNING.
THIS AFTERNOON AND EVENING...WHILE THE IA MCS IS LIKELY TO BEGIN
DECAYING SOME LATER THIS MORNING GIVEN LIMITED DEEP LAYER
SHEAR...REMNANTS OF WHAT IS LEFT ALONG WITH A FORECAST
CONVECTIVELY ENHANCED WAVE BY THE RAP WILL MOVE INTO THE WESTERN
CWA LATE THIS MORNING/EARLY THIS AFTERNOON. THE POTENTIAL FOR THIS
TO RE-INSTIGATE STORMS IS CERTAINLY THERE WITH THE UNSTABLE AIR
MASS STILL IN PLACE AND NOT EXPECTED TO VACATE UNTIL THIS EVE DUE
TO THE SLOW COOL FRONTAL APPROACH FROM THE NORTH. MLCAPE VALUES
OF 1500-3000 J/KG ARE FORECAST BY THE NAM TO BUILD ACROSS THE
WESTERN AND SOUTHERN CWA...BASICALLY IN THOSE AREAS AWAY FROM THE
STABILIZING ONSHORE COMPONENT OFF THE LAKE. GIVEN LITTLE
INHIBITION THE TRIGGER OF THIS IMPULSE/MCV COULD BE ENOUGH TO
SPARK STORMS AND THE SUITE OF CONVECTIVE ALLOWING GUIDANCE HAS
MEMBERS THAT DO JUST THAT. SO HAVE INCREASED POPS SOME INCLUDING
HOLDING ONTO THEM LONGER. COULD CONCEIVABLY SEE SOME STORMS LINGER
INTO THE EVE...NAMELY SOUTH OF I-80. WITH LIMITED UPPER FORCING
AND DYNAMICS THE POTENTIAL FOR ORGANIZATION TOWARD ROBUST STORMS
REMAINS PRIMARILY LOW...THOUGH A FEW ISOLATED NEAR TO SEVERE
STORMS MAY DEVELOP. TEMPERATURES TODAY LOOK TO PEAK IN THE MID 80S
IN THOSE AREAS AWAY FROM THE LAKE WHERE AN ONSHORE COMPONENT WILL
INCREASE THIS AFTERNOON. HIGHS LAKESIDE LOOK TO BE IN THE UPPER
70S.
QUIET WEATHER IS EXPECTED FRI AND SAT WITH HIGHS AROUND NORMAL.
DEW POINTS IN THE 40S STILL LOOK PLAUSIBLE FRI AFTERNOON FOR
SEVERAL AREAS. FRI NIGHT LOOKS CLEAR AND CALM WITH HIGH
CONFIDENCE SO CONTINUE TO ADVERTISE LOWER TO MID 50S IN MOST
OUTLYING AREAS.
NEXT WEEK IS THE FINAL WEEK OF METEOROLOGICAL SUMMER AND IT IS
SHAPING UP TO BE EVERY BIT SUMMER...AT LEAST THE FIRST HALF OF
IT BUT POSSIBLY MUCH OF IT. WITH THE CURRENT TROUGH OVER CANADA
ONLY GIVING A GLANCING BLOW...THE RIDGE BUILDS BACK NORTHWARD
ACROSS THE CENTRAL TO EASTERN PARTS OF THE COUNTRY BY LATE IN THE
WEEKEND. DPROG/DTS FROM BOTH THE EC AND GFS HAVE INDICATED A
FURTHER NORTH 500MB RIDGE CENTER IN THE PAST 24 HOURS...AND THIS
HAS RESULTED IN A WARMING GUIDANCE TREND. THE 594DM RIDGE
PLACEMENT JUST TO THE WEST...MODEST AND WARM SW/WSW 850-925MB
FLOW...AND A DRY COLUMN IS A PATTERN CONDUCIVE FOR WIDESPREAD
LOWER-MID 90S MON AND TUE WITH THE 90 THRESHOLD LIKELY REACHED IN
PLACES ON SUN. THE JET IS ADVERTISED TO BE ACTIVE ON THE NORTH SIDE
OF THIS WITH BROAD LOW PRESSURE ACROSS THE HIGH PLAINS LIKELY
RESULTING IN MULTIPLE MCS DEVELOPMENT IF THIS PATTERN IS CORRECT.
AT THIS TIME...THESE ARE EXPECTED TO REMAIN NORTH BUT DEPENDING ON
FREQUENCY OF THEM LIKELY WILL DICTATE HOW FAR AND QUICKLY SOUTH
THE SURFACE BOUNDARY ADVANCES. WITH NO REAL DEW POINT SCOURING TO
OUR SOUTH FROM OUR CURRENT BOUNDARY...THESE SHOULD REBOUND TO AT
LEAST THE UPPER 60S BY MON AND HOLD TO SLIGHTLY INCREASE AS LONG
AS THE HEAT PERSISTS. BY TUE THIS RESULTS IN FORECAST HEAT INDICES
AT 100 TO 105 IN SOME PLACES /NOT CHICAGO AT THIS TIME/. WHILE
THIS PERIOD IS STILL NUMEROUS DAYS OUT...THERE SEEM TO BE A
LIMITED SET OF FACTORS PRIOR TO WED THAT COULD REALLY BOTCH UP THE
HEAT GIVEN THE AMPLITUDE OF THE RIDGE. WILL CONTINUE TO HIGHLIGHT
IN THE HWO.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* A COUPLE ROUNDS OF THUNDERSTORMS MOVING ACROSS THE AREA THIS
MORNING.
* WIND SHIFT TO THE NORTH AND NORTHEAST WITH FROPA MID TO LATE
MORNING.
* POTENTIAL FOR MVFR CIGS BEHIND FRONT.
BMD
//DISCUSSION...UPDATED 12Z...
A COUPLE AREAS OF CONCERN FOR SHOWERS AND/OR THUNDERSTORMS THROUGH
MID MORNING TODAY. CURRENTLY BOTH AREAS ARE WITHIN AN AREA OF
MODERATE INSTABILITY AHEAD OF A FRONT...ROUGHLY 1500 J/KG MUCAPE
THAT STRETCHES FROM NORTH CENTRAL IOWA ESE INTO NORTHERN ILLINOIS.
FIRST AREA IS IMMEDIATELY WEST OF THE CHICAGO TERMINALS STRETCHING
FROM ROUGHLY EFT THROUGH RFD AND NEAR JOT...ON THE NOSE OF VERY
MODEST MID LEVEL THETA E ADVECTION. MOST OF THIS AREA SHOULD SLIDE
SOUTH OF ORD BUT MAY GET NEAR MDW AS IT TRACKS SOUTHEAST DOWN THE
RIDGE AXIS THIS MORNING. OF CONCERN FOR ORD WILL BE THE NORTHERN
PORTION OF THIS LINE NEAR EFT THAT MAY TRACK NEAR THE TERMINAL
AROUND 13Z. FARTHER WEST...A SECOND AREA OF STRONG THUNDERSTORMS HAS
BEEN UNDERGOING A GRADUAL WEAKENING TREND AS IT MOVES AWAY FROM THE
BETTER MOISTURE TRANSPORT FROM THE LOW LEVEL JET FOCUSED OVER
EASTERN NEBRASKA AND WESTERN IOWA. A COUPLE NOTABLE CIRCULATIONS
EMBEDDED WITHIN THIS AREA ON RADAR IMAGERY...THE FIRST OF WHICH WILL
OVERTAKE THE FIRST LINE OF THUNDERSTORMS...MOVING NEAR OR JUST NORTH
OF RFD AROUND 14Z AND ORD BETWEEN 1530 AND 1600Z. OUT AHEAD OF THIS
FEATURE MAY BE THE MOST FAVORABLE PERIOD FOR THUNDERSTORMS. THAT
SAID THE FAVORABLE THETA E ADVECTION OVER THE AREA WILL HAVE SHIFTED
FARTHER EAST...WHICH SHOULD ALLOW THE GENERAL WEAKENING TREND TO
CONTINUE. THE IDEA FOR NOW IS FOR A SOME FESTERING SHOWERS TO MOVE
INTO THE CHICAGO AREA AROUND 13Z OR SO...THOUGH CANNOT RULE OUT SOME
ISOLATED LIGHTNING LINGERING THAT LATE INTO THE MORNING.
A COLD FRONT WHICH CURRENTLY STRETCHES FROM FAR NORTHERN LAKE
MICHIGAN WSW ACROSS CENTRAL WISCONSIN AND INTO SOUTHERN MINNESOTA
WILL CONTINUE TO SLOWLY SAG SOUTH THROUGH THE DAY. TIMING THE WIND
SHIFT MAY BECOME A BIT DIFFICULT DEPENDING ON THE EVOLUTION OF
THUNDERSTORMS THIS MORNING...BUT EXPECT THE FRONT TO PUSH THROUGH
THE AREA BETWEEN 14Z AND 16Z WITH WINDS SHIFTING TO NORTHERLY...THEN
NORTHEAST BEHIND. SOME MODELS SOUNDINGS INDICATE POTENTIALLY MVFR
CIGS BEHIND THE FRONT BUT MOS GUIDANCE CONTINUES TO HOLD OFF AND
DONT SEE MUCH INDICATION ON UPSTREAM OBS TO INCLUDE IN THE TAF.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM CONFIDENCE IN TSRA IMPACTING THE TERMINALS AND TIMING.
* MEDIUM CONFIDENCE IN WIND TRENDS/TIMING SHIFT.
* LOW CONFIDENCE IN MVFR CIGS.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT THROUGH WEDNESDAY...VFR.
BMD
&&
.MARINE...
250 AM CDT
LOW PRESSURE OF 29.1 INCHES LIES OVER FAR NORTHERN QUEBEC WITH A
COLD FRONT SAGGING TO THE SOUTHWEST ACROSS THE UPPER PENINSULA OF
MICHIGAN AND INTO CENTRAL WISCONSIN. THIS FRONT WILL CONTINUE TO
MOVE SOUTH ACROSS LAKE MICHIGAN THIS MORNING. THE FRONT SHOULD BE
SOUTH OF LAKE MICHIGAN THIS AFTERNOON AS HIGH PRESSURE OF 30.2
INCHES BUILDS ACROSS THE UPPER MIDWEST. THE HIGH WILL SHIFT EAST
OVER LAKE MICHIGAN ON FRIDAY...THEN OVER THE EASTERN LAKES
SATURDAY. A BROAD AREA OF LOW PRESSURE AVERAGING 29.7 INCHES WILL
DEVELOP OVER THE NORTHERN PLAINS AND CANADIAN PRAIRIES SUNDAY AND
MONDAY...AND SLOWLY SHIFT EAST ACROSS THE GREAT LAKES THROUGH
MIDWEEK.
BMD
&&
.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...UPDATED
NWS CHICAGO/ROMEOVILLE IL
630 AM CDT THU AUG 22 2013
.DISCUSSION...
630 AM CDT
HAVE INCREASED POPS THROUGH THIS MORNING WITH OBSERVATIONAL AND
ENVIRONMENTAL ANALYSIS TRENDS ALL SUPPORTING CONVECTIVE LONGEVITY
IN THE AREA. THE ARC OF STORMS EARLY THIS MORNING FROM ROCKFORD
SOUTHEASTWARD LOOKS TO BE ROOTED ON AN ELEVATED AREA OF ISENTROPIC
ASCENT AND FOCUS ON SOME FORM OF ELEVATED CONVERGENCE. ONE OF
THESE STORMS PUT DOWN A QUICK TWO PLUS INCHES IN ROCHELLE. THE
HIGH PWAT AIR AND DEEP INSTABILITY ALONG WITH LITTLE IN THE WAY OF
SHEAR WILL CONTINUE TO MAKE THESE A MAINLY LOCALIZED HEAVY RAIN
THREAT. FURTHER WEST AN ORGANIZED AREA OF CONVECTION IS
PROGRESSING EAST ACROSS NORTHEAST IA. WHILE THIS IS SHOWING A
SLIGHT DIMINISHING TREND IN LIGHTING AND SOMEWHAT IN
STRUCTURE...THIS IS BEING DRIVEN BY AN MCV AND LIKELY WILL
OVERCOME THE CURRENT CONVECTION IN NORTH CENTRAL IL. TOGETHER
THESE AREAS WILL PROVIDE WIDESPREAD ENOUGH CONVECTION FROM
ROCKFORD THROUGH THE WESTERN METRO TO WARRANT HIGHER POPS AND QPF.
THE SEVERE WEATHER THREAT STILL REMAINS LIMITED AND REGIONALLY
THERE HAVE NOT BEEN ANY STORMS TO APPROACH SEVERE LIMITS. HOWEVER
THE EARLIER STORM IN ROCHELLE DID HAVE 39 MPH AND ANY CLUSTERS OF
CONVECTION WILL LIKELY HAVE TEMPORARY GUSTS AT OR ABOVE THAT GIVEN
SOME POSSIBLE WATER LOADING AND HIGH DCAPE AIR.
MTF
&&
.PREV DISCUSSION...
329 AM CDT
THE PRIMARY FORECAST CHALLENGES ARE CHANCES FOR STORMS TODAY AND
EARLY THIS EVE FOLLOWED BY THE HEAT...POTENTIALLY
PROLONGED...DURING NEXT WEEK.
THIS MORNING...A SOMEWHAT TRUBULENET...DISORGANIZED...AND EVEN
OVERTURNED ATMOSPHERE IS IN PLACE WITH ONE MCS HAVING GONE
THROUGH LATE LAST NIGHT ACROSS LAKE MI...WITH OUTFLOW STILL
PROGRESSING SOUTHEAST ACROSS THE CWA AS OF 315 AM. THIS IS
TRIGGERING A FEW STORMS THOUGH NOTHING ROBUST. FURTHER WEST AN MCS
EVOLVING EASTWARD ACROSS NORTHERN IA ALONG THE FRONTAL
BOUNDARY...WHICH IS VERY DIFFUSE EARLY TODAY...LOOKS TO WORK
EASTWARD WITHIN THE INSTABILITY MAXIMUM THROUGH THE MORNING. IN
ADVANCE OF THIS...NEAR THE BOUNDARY...THERE HAVE BEEN SOME
ISOLATED STORMS WITHIN THE HIGH PWAT AIR AND GENTLE WARM AIR
ADVECTION BUMPING UP AGAINST THE FRONT. SO ALL OF THIS LIKELY WILL
RESULT IN CONTINUED ISOLATED TO SCATTERED STORM GENERATION THIS
MORNING.
THIS AFTERNOON AND EVENING...WHILE THE IA MCS IS LIKELY TO BEGIN
DECAYING SOME LATER THIS MORNING GIVEN LIMITED DEEP LAYER
SHEAR...REMNANTS OF WHAT IS LEFT ALONG WITH A FORECAST
CONVECTIVELY ENHANCED WAVE BY THE RAP WILL MOVE INTO THE WESTERN
CWA LATE THIS MORNING/EARLY THIS AFTERNOON. THE POTENTIAL FOR THIS
TO RE-INSTIGATE STORMS IS CERTAINLY THERE WITH THE UNSTABLE AIR
MASS STILL IN PLACE AND NOT EXPECTED TO VACATE UNTIL THIS EVE DUE
TO THE SLOW COOL FRONTAL APPROACH FROM THE NORTH. MLCAPE VALUES
OF 1500-3000 J/KG ARE FORECAST BY THE NAM TO BUILD ACROSS THE
WESTERN AND SOUTHERN CWA...BASICALLY IN THOSE AREAS AWAY FROM THE
STABILIZING ONSHORE COMPONENT OFF THE LAKE. GIVEN LITTLE
INHIBITION THE TRIGGER OF THIS IMPULSE/MCV COULD BE ENOUGH TO
SPARK STORMS AND THE SUITE OF CONVECTIVE ALLOWING GUIDANCE HAS
MEMBERS THAT DO JUST THAT. SO HAVE INCREASED POPS SOME INCLUDING
HOLDING ONTO THEM LONGER. COULD CONCEIVABLY SEE SOME STORMS LINGER
INTO THE EVE...NAMELY SOUTH OF I-80. WITH LIMITED UPPER FORCING
AND DYNAMICS THE POTENTIAL FOR ORGANIZATION TOWARD ROBUST STORMS
REMAINS PRIMARILY LOW...THOUGH A FEW ISOLATED NEAR TO SEVERE
STORMS MAY DEVELOP. TEMPERATURES TODAY LOOK TO PEAK IN THE MID 80S
IN THOSE AREAS AWAY FROM THE LAKE WHERE AN ONSHORE COMPONENT WILL
INCREASE THIS AFTERNOON. HIGHS LAKESIDE LOOK TO BE IN THE UPPER
70S.
QUIET WEATHER IS EXPECTED FRI AND SAT WITH HIGHS AROUND NORMAL.
DEW POINTS IN THE 40S STILL LOOK PLAUSIBLE FRI AFTERNOON FOR
SEVERAL AREAS. FRI NIGHT LOOKS CLEAR AND CALM WITH HIGH
CONFIDENCE SO CONTINUE TO ADVERTISE LOWER TO MID 50S IN MOST
OUTLYING AREAS.
NEXT WEEK IS THE FINAL WEEK OF METEOROLOGICAL SUMMER AND IT IS
SHAPING UP TO BE EVERY BIT SUMMER...AT LEAST THE FIRST HALF OF
IT BUT POSSIBLY MUCH OF IT. WITH THE CURRENT TROUGH OVER CANADA
ONLY GIVING A GLANCING BLOW...THE RIDGE BUILDS BACK NORTHWARD
ACROSS THE CENTRAL TO EASTERN PARTS OF THE COUNTRY BY LATE IN THE
WEEKEND. DPROG/DTS FROM BOTH THE EC AND GFS HAVE INDICATED A
FURTHER NORTH 500MB RIDGE CENTER IN THE PAST 24 HOURS...AND THIS
HAS RESULTED IN A WARMING GUIDANCE TREND. THE 594DM RIDGE
PLACEMENT JUST TO THE WEST...MODEST AND WARM SW/WSW 850-925MB
FLOW...AND A DRY COLUMN IS A PATTERN CONDUCIVE FOR WIDESPREAD
LOWER-MID 90S MON AND TUE WITH THE 90 THRESHOLD LIKELY REACHED IN
PLACES ON SUN. THE JET IS ADVERTISED TO BE ACTIVE ON THE NORTH SIDE
OF THIS WITH BROAD LOW PRESSURE ACROSS THE HIGH PLAINS LIKELY
RESULTING IN MULTIPLE MCS DEVELOPMENT IF THIS PATTERN IS CORRECT.
AT THIS TIME...THESE ARE EXPECTED TO REMAIN NORTH BUT DEPENDING ON
FREQUENCY OF THEM LIKELY WILL DICTATE HOW FAR AND QUICKLY SOUTH
THE SURFACE BOUNDARY ADVANCES. WITH NO REAL DEW POINT SCOURING TO
OUR SOUTH FROM OUR CURRENT BOUNDARY...THESE SHOULD REBOUND TO AT
LEAST THE UPPER 60S BY MON AND HOLD TO SLIGHTLY INCREASE AS LONG
AS THE HEAT PERSISTS. BY TUE THIS RESULTS IN FORECAST HEAT INDICES
AT 100 TO 105 IN SOME PLACES /NOT CHICAGO AT THIS TIME/. WHILE
THIS PERIOD IS STILL NUMEROUS DAYS OUT...THERE SEEM TO BE A
LIMITED SET OF FACTORS PRIOR TO WED THAT COULD REALLY BOTCH UP THE
HEAT GIVEN THE AMPLITUDE OF THE RIDGE. WILL CONTINUE TO HIGHLIGHT
IN THE HWO.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* CONVECTIVE TRENDS OVER THE NEXT SEVERAL HOURS...AND AGAIN LATE
THIS MORNING AND EARLY AFTERNOON.
* WIND SHIFTING TO NORTH ONCE AGAIN LATE THURSDAY MORNING WITH A
COLD FRONT.
* POTENTIAL FOR MVFR CIGS BEHIND THE FRONT.
BMD
//DISCUSSION...UPDATED 09Z...
ADDITIONAL THUNDERSTORMS ARE DEVELOPING EARLY THIS MORNING WITHIN
A CORRIDOR OF UPWARDS OF 2000 J/KG MUCAPE THAT STRETCHES FROM
ROUGHLY NORTH CENTRAL IOWA INTO FAR NORTHERN ILLINOIS. COVERAGE IS
SOMEWHAT SCATTERED AT THE MOMENT AND EXPECT THIS TO REMAIN THE
CASE THROUGH THE EARLY MORNING. A CONVECTIVE COMPLEX MOVING EAST
ACROSS NORTH CENTRAL IOWA SHOWING SIGNS OF DEVELOPING AN MCV WHICH
IS EXPECTED TO MOVE INTO NORTH CENTRAL ILLINOIS AROUND 14Z AND
NORTHEAST ILLINOIS AROUND 15Z. IT IS QUITE POSSIBLE THAT THIS
COULD SPAWN ADDITIONAL THUNDERSTORMS OVER THE AREA 1-2 HOURS PRIOR
TO ITS ARRIVAL...THOUGH QUITE A BIT OF UNCERTAINTY STILL IN
EXACTLY WHERE THIS MAY DEVELOP WITH RESPECT TO THE TERMINALS...AND
COVERAGE.
PREVIOUS DISCUSSION...
SEVERAL CONCERNS IN THE SHORT TERM REVOLVING AROUND A COUPLE DIFFERENT
WINDOWS OF OPPORTUNITY FOR SHRA/TSRA...AND WIND DIRECTION WITH AN
OUTFLOW BOUNDARY RACING SOUTH DOWN LAKE MICHIGAN.
RADAR AND SATELLITE TRENDS INDICATE THAT CONVECTIVE ACTIVITY AND
COVERAGE IS GENERALLY ON DOWNWARD TREND. SEEMS REASONABLE FOR THIS
TREND TO CONTINUE AS WE FALL BEHIND A WAVE THAT IS MOVING AWAY FROM
THE AREA ACROSS LAKE MICHIGAN. THE LOW LEVEL JET SETS UP WELL TO OUR
WEST AND WOULD SUPPORT ONGOING CONVECTION OVER NEBRASKA/WESTERN
IOWA...BUT NOT LOCALLY.
ON AVERAGE...IR IMAGERY SHOWS WARMING CLOUD TOPS OVER THE
AREA...WITH THE COOLEST CLOUD TOPS BECOMING MUCH MORE ISOLATED. THE
AREA CURRENTLY OVER THE CHICAGO TERMINALS HAS LOST MOST OF ITS
LIGHTNING...EXCEPT ON THE SOUTHERN MOST STORMS WHICH WILL NOT IMPACT
THE TERMINALS. EXPECT THAT BY THE TIME THE 06Z TAFS GO INTO EFFECT
THIS AREA WILL BE SOUTH OF ORD...AND SHOULD CLEAR MDW BY 0630Z. NEXT
AREA OF CONCERN IS AN AREA OVER NORTHWEST ILLINOIS. IF THIS AREA
HOLDS TOGETHER...EXPECT IT TO BE THROUGH THE CHICAGO TERMINALS BY
AROUND 09Z. GIVEN THE DOWNWARD TRENDS THOUGH DO NOT ANTICIPATE THIS
TO IMPACT BEYOND RFD WHICH SHOULD CLEAR BY 730Z.
TO OUR NORTH...AN OUTFLOW BOUNDARY IS EVIDENT ON RADAR IMAGERY
RACING SOUTH ALONG THE COAST OF LAKE MICHIGAN. THE CONVECTION TO
SUSTAIN THIS PUSH DOWN THE LAKE HAS SHIFTED EAST OF THE
BOUNDARY...WHICH IS STRUGGLING TO PUSH VERY FAR INLAND...BUT THERE
ARE CURRENTLY NORTHEAST GUSTS OF AROUND 20-25 KTS ASSOCIATED WITH
THE BOUNDARY. WINDS ARE EXPECTED TO SHIFT NORTHEAST AND INCREASE
SHARPLY...THEN SHOULD SETTLE DOWN SHORTLY THEREAFTER AND RETURN
CLOCKWISE BACK TO A MORE SOUTHERLY WIND...AND EVENTUALLY
SOUTHWEST. BASED ON THE CURRENT TRAJECTORY...IT WILL BE NEAR
ORD...MDW...AND GYY BY 630Z.
DID NOT MAKE ANY BIG CHANGES BEYOND THE FIRST 6 HOURS OF THE TAF.
FRONTAL TIMING STILL APPEARS TO BE AROUND 14Z WITH WINDS SHIFTING
TO NORTH...THEN NORTHEAST BEHIND THE FRONT. CANT COMPLETELY RULE
OUT ADDITIONAL THUNDERSTORMS DEVELOPING NEARBY TOMORROW AS WE
QUICKLY DEVELOP MODERATE INSTABILITY OVER THE AREA...BUT IT
APPEARS THE BEST FORCING WILL SHIFT SOUTH OF THE TERMINALS. SOME
MODEL SOUNDINGS CONTINUE TO INDICATE THE POTENTIAL FOR MVFR CIGS
TO DEVELOP RIGHT BEHIND THE FRONT FOR A COUPLE HOURS...THOUGH MOS
GUIDANCE INDICATES CONDITIONS WILL REMAIN VFR BEHIND THE FRONT.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* LOW CONFIDENCE IN TSRA TRENDS THROUGH THE MORNING.
* LOW CONFIDENCE IN MVFR CIGS BEHIND FRONT.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR. NORTHEAST WINDS.
SATURDAY...VFR. EASTERLY WINDS.
SUNDAY THROUGH TUESDAY...VFR.
RC
&&
.MARINE...
250 AM CDT
LOW PRESSURE OF 29.1 INCHES LIES OVER FAR NORTHERN QUEBEC WITH A
COLD FRONT SAGGING TO THE SOUTHWEST ACROSS THE UPPER PENINSULA OF
MICHIGAN AND INTO CENTRAL WISCONSIN. THIS FRONT WILL CONTINUE TO
MOVE SOUTH ACROSS LAKE MICHIGAN THIS MORNING. THE FRONT SHOULD BE
SOUTH OF LAKE MICHIGAN THIS AFTERNOON AS HIGH PRESSURE OF 30.2
INCHES BUILDS ACROSS THE UPPER MIDWEST. THE HIGH WILL SHIFT EAST
OVER LAKE MICHIGAN ON FRIDAY...THEN OVER THE EASTERN LAKES
SATURDAY. A BROAD AREA OF LOW PRESSURE AVERAGING 29.7 INCHES WILL
DEVELOP OVER THE NORTHERN PLAINS AND CANADIAN PRAIRIES SUNDAY AND
MONDAY...AND SLOWLY SHIFT EAST ACROSS THE GREAT LAKES THROUGH
MIDWEEK.
BMD
&&
.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 INDIANAPOLIS IN
644 AM EDT THU AUG 22 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 342 AM EDT THU AUG 22 2013
A COLD FRONT WILL TRACK THROUGH CENTRAL INDIANA TODAY AND TONIGHT
AND BRING SCATTERED THUNDERSTORMS TO CENTRAL INDIANA. HIGH PRESSURE
WILL BUILD ACROSS THE GREAT LAKES IN WAKE OF THE FRONTAL
PASSAGE...WITH DRY SEASONABLE CONDITIONS FRIDAY AND SATURDAY. THE
EXPANSION OF A BROAD UPPER RIDGE WILL SIGNAL THE BEGINNING OF A
WARMING TREND ON SUNDAY...WITH HOT WEATHER EXPECTED TO PERSIST FOR
MUCH OF NEXT WEEK.
&&
.NEAR TERM /TODAY/...
ISSUED AT 342 AM EDT THU AUG 22 2013
SCATTERED CONVECTION CONTINUES TO DEVELOP EARLY THIS MORNING AHEAD
OF WEAKENING STORM COMPLEX OVER LOWER MICHIGAN AND NORTHERN INDIANA.
HIGH CLOUDS ASSOCIATED WITH THE STORMS HAVE QUICKLY ENCOMPASSED A
GOOD PORTION OF THE FORECAST AREA ALREADY. TEMPS WERE PREDOMINANTLY
IN THE 60S AS OF 07Z.
BULK OF THE MODEL GUIDANCE LARGELY STRUGGLING WITH CURRENT
CONDITIONS AND SPECIFICALLY WITH THE AFOREMENTIONED COMPLEX TO THE
NORTH. CONVECTION IS WEAKENING AND DIMINISHING IN COVERAGE AS
EXPECTED WITH IT MOVING INTO A LESS FAVORABLE ENVIRONMENT OVER THE
FORECAST AREA. HRRR BEGINNING TO CATCH ON TO THE FASTER ARRIVAL OF
CONVECTION...AND MOST RECENT DATA SUGGESTIVE OF SCATTERED CONVECTION
IN A PROGRESSIVELY WEAKENED STATE MIGRATING INTO NORTHERN COUNTIES
THROUGH DAYBREAK. BEST COVERAGE TO RAINFALL SHOULD IMPACT NORTHEAST
COUNTIES OVER THE NEXT SEVERAL HOURS WITH PRECIP MORE SCATTERED
FURTHER WEST. HAVE BUMPED UP POPS THROUGH MID MORNING OVER THE
NORTHERN HALF OF THE FORECAST AREA FROM PREVIOUS FORECAST AS A
RESULT.
LOWER CONFIDENCE IN POTENTIAL CONVECTIVE COVERAGE AS THE DAY
PROGRESSES. STRONGER FORCING ALOFT MOVING INTO THE EASTERN GREAT
LAKES AND ANTICIPATE MUCH OF THE CONVECTION WILL EVENTUALLY END UP
TO THE EAST OF THE REGION IN CLOSER PROXIMITY TO THE BETTER FORCING.
CONVECTIVE COVERAGE FOR THE AFTERNOON WILL DEPEND ON HOW QUICKLY
CLOUD DEBRIS DIMINISHES AND THE AMOUNT OF INSTABILITY OVER THE
REGION LATER TODAY. MAIN CATALYSTS FOR CONVECTIVE DEVELOPMENT DURING
THE AFTERNOON WILL BE FORCING ASSOCIATED WITH THE FRONT AND
AVAILABLE INSTABILITY. IN ADDITION...SHORTWAVE ALOFT ASSOCIATED WITH
CONVECTIVE COMPLEX CURRENTLY OVER THE MISSOURI VALLEY WILL TRACK
INTO THE REGION BY LATE AFTERNOON AND MAY AID IN ADDITIONAL
CONVECTIVE DEVELOPMENT. WILL CONTINUE WITH 40-50 POPS DURING THE
AFTERNOON.
TEMPS...DESPITE PRESENCE OF ADDITIONAL HIGH CLOUDS THIS MORNING...
RECENT TREND HAS BEEN FOR TEMPS TO MAX OUT NEAR THE HIGH END OF
GUIDANCE AND SEE NO REASON TO DEVIATE FROM PERSISTENCE TODAY EVEN
WITH A GREATER THREAT FOR STORMS. WILL LEAN CLOSE TO MAV GUIDANCE.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
ISSUED AT 342 AM EDT THU AUG 22 2013
FORECAST CHALLENGES FOCUS ON PRECIP CHANCES TONIGHT AND TEMPS
THROUGHOUT THE SHORT TERM.
BULK OF SCATTERED CONVECTION LIKELY TO BE FOCUSED ALONG AND SOUTH OF
I-70 BY THIS EVENING AS THE INCREASINGLY DIFFUSE FRONTAL BOUNDARY
PROGRESSES SOUTH. WILL MAINTAIN HIGHEST POPS OVER SOUTHERN COUNTIES
AND PREDOMINANTLY DURING THE EVENING...WITH PRECIP CHANCES ENDING
FROM THE NORTH AFTER MIDNIGHT AS THE FRONT CONTINUES MOVING SOUTH
INTO THE TENNESSEE VALLEY. HIGH PRESSURE WILL MOVE ACROSS THE
GREAT LAKES LATE TONIGHT WITH DRIER AIR ADVECTING INTO THE REGION
FROM THE NORTH. DEEPER MOISTURE WILL BE PUSHED TO THE SOUTH WITH
PRECIP LIKELY TO BE COMPLETELY OUT OF SOUTHERN COUNTIES BY 12Z
FRIDAY.
THE HIGH WILL TRACK THROUGH THE GREAT LAKES FRIDAY WITH NORTHEAST
WINDS CONTINUING TO BRING DRIER AIR AND SUBSIDENCE ALOFT INTO THE
REGION FROM THE NORTH. PRESENCE OF COLD ADVECTION IN THE WAKE OF THE
FRONTAL BOUNDARY WILL ENABLE SOME CU DEVELOPMENT THROUGH THE
AFTERNOON...ESPECIALLY ACROSS THE SOUTHERN HALF OF THE FORECAST AREA
WHERE LOW LEVEL MOISTURE WILL BE MORE PREVALENT. CU WILL DIMINISH
TOWARDS SUNSET WITH SKIES BECOMING MAINLY CLEAR AS EVEN DRIER AIR
BUILDS IN FROM THE NORTHEAST. DRY AND SEASONABLE CONDITIONS CAN BE
EXPECTED FOR THE REMAINDER OF THE SHORT TERM AS THE HIGH CENTERS
ACROSS NEW ENGLAND AND THE MID ATLANTIC. PREDOMINANT EASTERLY FLOW
WILL CONTINUE TO PUMP DRY AIR INTO CENTRAL INDIANA. MODEL SOUNDINGS
SUGGESTIVE OF MAINLY SUNNY CONDITIONS SATURDAY WITH LITTLE TO NO CU
DEVELOPMENT ANTICIPATED.
TEMPS...LOW LEVEL THERMALS REMAIN SUPPORTIVE OF WARMER MAVMOS
GUIDANCE AND WILL CONTINUE TO TREND HIGH TEMPS TOWARDS THE MAV.
RECENT DRY STRETCH ALSO WOULD SUPPORT WARMER TEMPS WITH HIGHS BOTH
FRIDAY AND SATURDAY EXPECTED TO BE IN THE LOW/MID 80S FOR MUCH OF
THE REGION. POTENTIAL FOR NEAR IDEAL RADIATIONAL COOLING CONDITIONS
BOTH FRIDAY AND SATURDAY NIGHTS WITH MAINLY CLEAR SKIES AND LIGHT
WINDS. SHOULD BE A GOOD SETUP FOR A RURAL-URBAN SPLIT IN TEMPS AS
OUTLYING LOCALES DROP INTO THE 50S.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
ISSUED AT 244 AM EDT THU AUG 22 2013
MODELS ARE CLOSE ENOUGH THAT THE ALLBLEND INITIALIZATION CAN BE USED
FOR MOST FEATURES...UNLESS NOTED BELOW. FOCUS IS MAINLY ON
TEMPERATURES.
A LARGE UPPER HIGH WILL BUILD ACROSS THE CENTRAL USA DURING THE
EXTENDED...AND THIS HIGH WILL BE THE MAIN INFLUENCE ON CENTRAL
INDIANA WEATHER. TEMPERATURES WILL WARM AS THE HIGH BUILDS IN AND
REMAINS IN CONTROL...SO HIGHS WARMING INTO THE 90S LOOK GOOD. BUMPED
UP ALLBLEND A BIT ON SOME DAYS AS IT SEEMED A LITTLE TOO COOL GIVEN
THE EXPECTED CONDITIONS.
REMOVED ALLBLEND/S CHANCES FOR RAIN THROUGH THE PERIOD. AT THE
MOMENT IT LOOKS LIKE ANY RING OF FIRE THUNDERSTORMS SHOULD REMAIN
OFF TO THE NORTH AND EAST...ESPECIALLY GIVEN THAT 700MB TEMPERATURES
WILL EXCEED 10C AND SHOULD CAP THINGS THROUGH THE PERIOD. OF COURSE
CANNOT ABSOLUTELY RULE OUT A POP UP STORM IN THE AFTERNOON...BUT
ODDS ARE TOO LOW TO MENTION AT THIS TIME.
&&
.AVIATION /DISCUSSION FOR THE 22/1200Z TAF ISSUANCE/...
ISSUED AT 644 AM EDT THU AUG 22 2013
OUTSIDE OF ANY PATCHY FOG EARLY AND OUTSIDE OF CONVECTION
ANYTIME...EXPECT VFR CONDITIONS.
CIRRUS SHIELD HAS HELPED KEEP FOG AT BAY THIS MORNING. FOCUS IS THEN
ON SCATTERED CONVECTION MOVING INTO THE AREA. CONVECTION SHOULD
WEAKEN SOME THIS MORNING AS TYPICALLY HAPPENS THIS TIME OF DAY. THUS
FEEL THAT ONLY VCSH SHOULD COVER IT MOST SITES. DID GO VCTS AT KLAF
AS THAT STATION IS CLOSEST TO CURRENT TSRA.
AS A COLD FRONT MOVES INTO CENTRAL INDIANA TODAY ADDITIONAL
SCATTERED CONVECTION SHOULD DEVELOP. THERE IS UNCERTAINTY THOUGH ON
HOW THEY WILL DEVELOP GIVEN LINGERING CLOUD COVER FROM THIS
MORNING/S CONVECTION. THUS CONTINUED WITH VCTS THIS AFTERNOON. LATER
UPDATES WILL BE ABLE TO REFINE FORECASTS.
FRONT WILL SINK SOUTH OF THE AREA THIS EVENING ENDING THE
CONVECTION. CEILINGS SHOULD REMAIN VFR.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....50
AVIATION...50
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AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
958 AM CDT THU AUG 22 2013
.UPDATE...
ISSUED AT 951 AM CDT THU AUG 22 2013
THE MCS ALONG THE WI/IL BORDER IS STARTING TO DECAY. THE OUTFLOW
BOUNDARY FROM THIS MCS IS DOWN TO I-80 AND WILL DICTATE FUTURE
CONVECTIVE TRENDS.
THE FCST WAS UPDATED TO SHOW MAINLY DRY CONDITIONS ALONG/SOUTH OF
HWY 30. HOWEVER...SINCE THOSE GRIDS WERE DONE NEW CONVECTION HAS
DEVELOPED BETWEEN KALO AND KCID WITH SOME SHRA IN THE
KCID/KDBQ/KMLI TRIANGLE.
NO MODEL IS CURRENTLY HANDLING THE SITUATION VERY WELL. THUS
NOWCASTING TOOLS WILL BE USED HEAVILY. THE MCS TOOL WHEN APPLIED
TO THE CURRENT RAP TRENDS IS SUGGESTING A BULK OF THE AREA WILL
REMAIN DRY TODAY WITH PERHAPS ISOLATED TO SCATTERED CONVECTION
ONCE THE MCS DISSIPATES. ..08..
UPDATE ISSUED AT 646 AM CDT THU AUG 22 2013
I HAVE UPDATED POPS ONCE AGAIN...NOW TO SHARPEN THE CUT FROM
CATEGORICAL NORTH...THE SLIGHT CHANCE ALONG I-80. THIS EVENT
BECOME MORE CHAOTIC THIS AFTERNOON...AND LOW CHANCE POPS ARE
RETAINED FOR MOST OF THE CWA.
ERVIN
&&
.SYNOPSIS...
ISSUED AT 308 AM CDT THU AUG 22 2013
A SLOW MOVING COLD FRONT IS CURRENTLY POSITIONED FROM NORTHERN
NEBRASKA...THROUGH SOUTHERN MINNESOTA AS OF 2 AM. EARLIER...SURFACE
BASED STORMS HAD BEEN PRESENT ALONG THE FRONT FROM NORTH CENTRAL
IOWA THROUGH WISCONSIN...BUT THESE HAVE LONG SINCE DISSIPATED.
ELEVATED CONVECTION IS FOUND IN TWO ZONES...ONE JUST TO THE EAST
OVER NORTHERN ILLINOIS AND INDIANA...AND ANOTHER TO THE WEST. THE
CONVECTION TO THE WEST IS SUPPORTED BY A WEAK SHORT WAVE TROF...AND
IS MUCH MORE ORGANIZED. THIS WESTERN CLUSTER...OR AT LEAST THE SHORT
WAVE ASSOCIATED WITH IT...WILL BE ENTERING OUR CWA TOWARD 12Z TODAY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 308 AM CDT THU AUG 22 2013
WITH THE BOUNDARY OVER THE CWA THROUGH THIS EVENING...IT IS CERTAIN
THAT WHAT EVER CONVECTION MOVES FROM WEST TO EAST ALONG THE FRONT
WILL HIT SOME PORTION OF THE CWA. AS OF NOW...MODELS TAKE A MATURE
MCS EAST THROUGH THE NORTHERN HALF OF THE CWA. THIS SEEMS QUITE
POSSIBLE...BUT GIVEN OUR RECENT STRETCH OF DRY WEATHER...I WILL WAIT
UNTIL IT HOLDS TOGETHER THROUGH CENTRAL IOWA BEFORE GREATLY RAISING
POPS. THE ATMOSPHERE MODESTLY SUPPORTS MAINTENANCE OF THIS
CONVECTIVE CLUSTER TODAY...AND AN UPGRADE FROM LIKELY/CHANCE POPS TO
CATEGORICAL IS QUITE POSSIBLE PRIOR TO 5 AM...BUT AFTER OUR EARLY
MORNING FORECAST ISSUANCE AT 3 AM. AT THIS TIME...IT APPEARS
LOCATIONS GENERALLY ALONG AND NORTH OF HIGHWAY 30...POSSIBLY THROUGH
INTERSTATE 80 STAND TO SEE THE BEST CHANCE OF WIDESPREAD CONVECTION
THIS MORNING. OTHERWISE...WE WILL KEEP CHANCE POPS GOING ALL
AFTERNOON...AND THIS EVENING AS THE FRONTAL BOUNDARY IS OVERHEAD.
SOME ELEVATED CELLS ARE AGAIN POSSIBLE OVERNIGHT TONIGHT...BUT THESE
SHOULD GENERALLY BE UNORGANIZED...AND TIED TO THE SOUTHWESTERN CWA.
TEMPERATURES TODAY WILL HAVE TO DEAL WITH PLENTY OF CLOUDS AND
POSSIBLY WIDESPREAD RAINFALL...THUS LOWER 80S NORTH TO UPPER 80S
SOUTH SEEM THE SAFEST BET FOR HIGHS. TONIGHTS LOWS UNDER SOME CLOUD
COVER...ARE LIKELY TO BE A BIT WARMER THAN EARLIER FORECAST. FOR NOW
AM THINKING UPPER 50S NORTHEAST TO UPPER 60S SOUTHWEST.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 335 AM CDT THU AUG 22 2013
THE EXTENDED FORECAST IN A NUTSHELL...HOT...HUMID...AND DRY. THE
PERIOD WILL BE DOMINATED BY A BUILDING UPPER LEVEL RIDGE OVER THE
NATIONS MIDSECTION WHICH WILL STRENGTHEN INTO NEXT WEEK...RESULTING
IN DRY CONDITIONS...AND A POSSIBLY A PROLONGED HEAT WAVE. OTHER THAN
A VERY SLIGHT CHANCE OF POPS IN THE SW FOR FRI AS AN 850MB MOISTURE
LINGERS OVER THE AREA...THE EXTENDED LOOKS DRY. HIGHS FRI WILL BE
IN THE LOWER 80S NORTH...TO UPPER 80S SOUTH. SLIGHTLY WARMER TEMPS
ARE ON TAP FOR SAT...WITH READINGS IN THE MID 80S NE TO NEAR 90 SW.
WE THEN TURN UP THE BURNER FOR SUNDAY THROUGH WEDNESDAY...AS 850
TEMPS WARM INTO THE LOW-MID 20S...TRANSLATING TO HIGHS EACH DAY IN
THE LOWER TO MIDDLE 90S...WHICH MAY APPROACH RECORD LEVELS.
HUMIDITY LEVELS WILL ALSO INCREASE DURING THIS TIME...WITH DEW
POINTS IN THE UPPER 60S TO LOW 70S. OVERNIGHT LOWS SUN THROUGH WED
WILL BE IN THE LOW-MID 70...ALSO POSSIBLE RECORD WARM LOWS. DAYTIME
HEAT INDICES WILL BE IN THE MID 90S TO AROUND 100. THE REAL HEAT
DOME IS STILL WEST OUT OVER THE PLAINS...INDICATING NO REAL SIGNS OF
THE HEAT WAVE BREAKING ANY TIME SOON. STILL TOO SOON TO ISSUE HEAT
HEADLINE PRODUCTS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 640 AM CDT THU AUG 22 2013
A PERIOD OF STRONG THUNDERSTORM ACTIVITY SHOULD AFFECT DBQ FROM
12Z TO 14Z THIS MORNING WITH HEAVY RAIN AND GUSTY WINDS.
OTHERWISE...SCATTERED TO ISOLATED SHOWERS OR STORMS REMAIN
POSSIBLE AT CID MLI AND BRL...BUT FROM HERE ON OUT IT LOOKS TOO
LIMITED TO INCLUDE IN ANY TAF BEYOND VICINITY SHOWERS. WINDS TODAY
WILL BE LIGHT SOUTH TO LIGHT NORTH...UNDER 8 KTS...AS A FRONT
DROPS SOUTH OVER THE AREA. BY TONIGHT...SKIES WILL CLEAR FROM
NORTH TO SOUTH...AND SOME PATCHY MVFR FOG COULD
DEVELOP...ESPECIALLY IN TERMINALS THAT SEE RAIN TODAY...AND AT
THIS POINT...THAT WOULD BE DBQ.
ERVIN
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...14
AVIATION...ERVIN
AREA FORECAST DISCUSSION
NWS GOODLAND KS
457 AM MDT THU AUG 22 2013
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 248 AM MDT THU AUG 22 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW BROAD RIDGE STILL IN
PLACE ACROSS THE SOUTHERN PLAINS...WITH ACTIVE ZONAL FLOW ACROSS
THE NORTHERN PLAINS. SEVERAL SHORTWAVE TROUGHS ARE IN PLACE WITHIN
THE MEAN FLOW OVER CENTRAL NEBRASKA AND WESTERN WYOMING. AT THE
SURFACE A COLD FRONT HAS PUSHED SOUTH OVER OUR CWA AND IS
CURRENTLY EXTENDING FRONT NORTON TO CHEYENNE WELLS BEFORE TURNING
BACK TO THE NORTH ALONG THE THE FRONT RANGE IN COLORADO.
THUNDERSTORMS DEVELOPED OVERNIGHT AHEAD OF THIS FRONT IN THE FAR
EASTERN PART OF THE CWA...WITH SUPPORT FROM H85 50KT JET AND
STRONG THETA-E CONVERGENCE IN THE H85-H7 LAYER. SHORT RANGE
GUIDANCE SUPPORTS THIS ACTIVITY PULLING OFF THE EAST THROUGH
SUNRISE...HOWEVER LITTLE WILL CHANGE REGARDING INSTABILITY/FORCING
SO WILL NEED TO MONITOR/REEVALUATE IF I NEED TO KEEP POPS MENTION
BEYOND 15Z FOR THESE LOCATIONS. ADDITIONAL THUNDERSTORM IS
EXPECTED TO DEVELOP THIS AFTERNOON GENERALLY ALONG THE THE STALLED
FRONT...WITH ADDITIONAL FORCING IN THE LATE AFTERNOON THROUGH
EVENING ASSOCIATED WITH SHORTWAVE TROUGH PASSAGE IN NEBRASKA. WITH
FRONT OVER OUR CWA WE SHOULD SEE BETTER COVERAGE ALONG
FRONT. BETTER INSTABILITY GENERALLY TO THE NORTH OF THE FRONT
WHERE TD VALUES IN THE 60S WILL BE...SO I KEPT CHANCE POPS
GENERALLY OVER THE NW CWA. NAM/RAP BOTH SHOW SB/ML CAPE IN EXCESS
OF 2000 J/KG NORTH OF THIS FRONT WHICH COULD CERTAINLY SUPPORT
STRONG UPDRAFTS. SHEER ON THE OTHER HAND IS NOT QUITE AS
STRONG (0-6KM 20-25KT). THERE DOES APPEAR TO BE ENOUGH SUPPORT FOR
AN ELEVATED LARGE HAIL/STRONG WIND THREAT WITH THUNDERSTORMS THAT
DEVELOP.
AFTER TOMORROW NIGHT PRECIP CHANCES DECREASE SIGNIFICANTLY WITH
INCREASING CAP AND STRONGER SUBSIDENCE ASSOCIATED WITH BUILDING
RIDGE. THERE IS SOME INDICATION OF THUNDERSTORMS MOVING INTO THE
FAR NW PART OF THE CWA FRIDAY AFTERNOON/EVENING...SO I ADDED
SLIGHT CHANCE POPS. BY SATURDAY THE MEAN STORM TRACK WILL HAVE
SHIFTED FAR ENOUGH NORTH WITH STRONG CINH AND LARGE SCALE
SUBSIDENCE INHIBITING AFTERNOON/EVENING CHANCES.
TEMPS WILL DROP CLOSER TO SEASONAL NORMS TODAY BEHIND FRONT IN
THE UPPER 80S/LOW 90S. TH TREND WILL BE MUCH ABOVE NORMAL FRIDAY
AND SATURDAY WITH STRONG RIDGE (595DM) AND STRONG WAA ASSOCIATED
WITH SOUTHERLY FLOW EAST OF STRENGTHENING LEE TROUGH. HAVE TRENDED
TEMPS TOWARDS UPPER 90S BASED ON MIXING WED...AND MIGHT BE A FEW
DEGREES TOO COOL WITH TEMPS NEAR 100F NOT OUT OF THE QUESTION.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 248 AM MDT THU AUG 22 2013
FORECAST PATTERN FOR THE WEEKEND AND EARLY NEXT WEEK HAS CHANGED
LITTLE OVER THE PAST FEW DAYS. A STRONG UPPER-LEVEL RIDGE WILL BE
CENTERED OVER THE CENTRAL PLAINS FOR MUCH OF THE PERIOD...WITH THE
GEM AND ECMWF PLACING THE UPPER HIGH JUST EAST OF THE CENTRAL
PLAINS. WHILE THE RIDGE IS IN PLACE PRECIP CHANCES WILL BE NEAR-NIL
AS DISTURBANCES ROTATE AROUND THE RIDGE. TEMPS WILL BE WELL ABOVE
NORMAL WITH 850MB TEMPS IN THE LOW 30S C...TRANSLATING TO HIGHS IN
THE MID TO UPPER 90S. WOULD NOT BE SURPRISED TO SEE SOME SPOTS HIT
THE TRIPLE DIGITS MON OR TUES...THE HEAT PEAKING AROUND TUESDAY
BEFORE THE RIDGE SHIFTS A BIT FURTHER EAST INTO THE MIDDLE OF THE
WEEK. WINDS DURING THE PERIOD WILL BE PRETTY BREEZY OUT OF THE
SOUTH AT 15 TO 20 MPH DURING THE AFTERNOONS AS A NORTH-SOUTH
ORIENTED SURFACE TROUGH DEVELOPS IN EASTERN COLORADO.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 457 AM MDT THU AUG 22 2013
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE TAF PERIOD AT
BOTH KGLD AND KMCK TERMINALS. PRIMARY AVIATION CONCERN IS
THUNDERSTORMS POSSIBLY DEVELOPING WITHIN THE VICINITY OF BOTH
TERMINALS THIS AFTERNOON/EVENING ALONG AND NORTH OF STALLED FRONT.
WHILE CONFIDENCE IS INCREASING IN ISOLATED-SCATTERED THUNDERSTORMS
INITIATING ACROSS NW KS AND SW NE...I AM NOT CONFIDENT IN COVERAGE
IN RELATION TO BOTH TERMINALS. FRONT POSITION SHOULD BE JUST
SOUTH...AND BEST UPPER LEVEL SUPPORT WILL BE WELL TO THE NORTH
LATE TONIGHT. WILL HOLD OFF ON ADDING VCTS GROUP THIS TAF
ISSUANCE. SUSTAINED WINDS SHOULD REMAIN BELOW 12KT AT BOTH
TERMINALS WITH WINDS SHIFTING TO THE SOUTH- SOUTHEAST BY THIS
EVENING AS FRONT BEGINS TO LIFT BACK TO THE NORTH.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...JJM
AVIATION...DR
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
631 AM CDT THU AUG 22 2013
.UPDATE...
FOR 12Z AVIATION DISCUSSION BELOW
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 410 AM CDT THU AUG 22 2013
SHORT TERM TRENDS POINT TO SOME ISOLATED THUNDER LIFTING AS FAR
NORTH AS DECAYING FRONTAL BOUNDARY...WITHIN INSTABILITY AXIS AND
NORTHERN PERIPHERY OF COMPLEX OVER IOWA. WILL HAVE TO INCLUDE THIS
FOR MUCH OF THE MORNING HOURS ANYWAY.
THIS CONVECTION IS BEING FORCED BY SOME WEAK LAYERED FRONTOGENESIS.
THIS IS PROGGED BE THE HRRR AND MEMBER 1 AND 2 OF THE HOPWRF TO
GRADUALLY WEAKEN AND DROP FARTHER SOUTH AS DRIER AIR TRIES TO DROP
SOUTHWEST ERODING THE BOUNDARY. SHOULD SEE GRADUAL DRYING THEN INTO
THE AFTERNOON...AS SURFACE HIGH DROPS SOUTHEAST INTO TONIGHT.
CLOUDS SHOULD GIVE WAY TO CLEARING DURING THE DAY...AND CONTINUE
THIS TREND THROUGH THE NIGHT. TEMPERATURES COOL A BIT TO THE LOWER
AND MIDDLE 80S OVER MOST OF THE AREA TODAY. LOWS SHOULD COOL TO
AROUND 50 EAST AND AROUND 60 TO THE SOUTHWEST TONIGHT...AS DRIER AIR
MOVES ACROSS.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 410 AM CDT THU AUG 22 2013
THE MAIN WEATHER HEADLINE IN THE LONG TERM PORTION OF THE FORECAST
WILL BE BUILDING HEAT...AS MID LEVEL HEIGHTS GRADUALLY RISE IN
CONJUNCTION WITH THE EXTENSIVE RIDGE OVER THE CENTRAL CONUS. THE RETURN
OF THE HOT WEATHER WILL BE MET WITH THE ARRIVAL OF A WARM FRONT.
HAVE RETAINED 20-40 POPS FOR FRIDAY NIGHT INTO SATURDAY MORNING AS
THE AFOREMENTIONED FRONT BEGINS TO LIFT ACROSS THE AREA. ALTHOUGH
THE ORIENTATION OF THE 35-40KT PROGGED LLJ IS NOT IDEAL FOR
WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY...INDICATIONS ARE THAT
IT SHOULD BE ADEQUATE FROM CENTRAL MN INTO WEST CENTRAL WI TO
WARRANT LOW CHANCE POPS CENTERED BETWEEN 06Z AND 18Z SATURDAY.
AFTER THAT...OTHER THAN A FEW STRAY SHOWERS/TS NORTH OF INTERSTATE
94 CLOSER TO THE BOUNDARY...MOSTLY DRY CONDITIONS ARE EXPECTED
THROUGH MONDAY AS THE WARM FRONT LIFTS INTO NORTHERN MN. AS THIS
OCCURS...TEMPERATURES WILL MODERATE INTO THE LOW/MID 90S FOR
SUNDAY THROUGH TUESDAY AS DEWPOINTS CREEP TO AROUND 70 DEGREES.
THIS COULD MEAN A PROLONGED PERIOD WITH A HEAT ADVISORY...WITH MAX
HEAT INDICES NEARING 100 DEGREES AND OVERNIGHT LOW TEMPS REMAINING
ELEVATED IN THE LOW/MID 70S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 635 AM CDT THU AUG 22 2013
EXPECT THE SHRA/TS ACTIVITY TO STAY SOUTH OF THE TAF SITES
TODAY....WITH DRIER AIR WORKING IN FROM THE NORTH AS ILLUSTRATED
BY DEWPOINTS IN THE 40S ACROSS THE NORTHERN PORTION OF THE AREA
/CENTRAL MN/. FAIRLY EXTENSIVE CLOUD COVERAGE AT THE START OF THE
PERIOD SHOULD GIVE WAY TO CLEARING THIS AFTERNOON...WITH LIGHT
WINDS AS SURFACE HIGH PRESSURE SETTLES IN. NORTHEAST WINDS NEARING
10 MPH AT THE START OF THE PERIOD...DECREASING AND BECOMING LIGHT
AND VARIABLE BY 00Z.
KMSP...
CU AND CIRRUS BECOME LESS EXTENSIVE THROUGHOUT THE DAY...WITH
A MOSTLY CLEAR SKY EXPECTED BY 00Z. NORTHEAST WINDS 020-050 AROUND
9 KTS BECOME LIGHT AND VARIABLE BY 00Z.
/OUTLOOK FOR KMSP/
FRI...VFR. SCHC OF SHRA/TSRA LATE. SE WIND 5 TO 10 KTS.
SAT...OCNL MVFR-MAINLY VFR CIGS. CHANCE TSRA/SHRA. S WIND 12-18
KTS G 24 KTS.
SUN...VFR. SW WIND 12-18 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...DWE
LONG TERM...LS
AVIATION...LS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
742 AM EDT THU AUG 22 2013
.SYNOPSIS...
A COLD FRONT WILL SWEEP ACROSS THE REGION LATE TODAY...BRINGING A
ROUND OF SHOWERS AND THUNDERSTORMS. AFTER THIS...HIGH PRESSURE WILL
BUILD DOWN FROM THE UPPER LAKES AND BRING COOLER TEMPERATURES AND
FAIR WEATHER WHICH WILL LAST THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AT 700 AM...THERE WAS AN UPPER LEVEL TROF ACROSS THE MID ATLANTIC
STATES AND BROKEN SHOWER AND THUNDERSTORM ACTIVITY AHEAD OF A COLD
FRONTAL BOUNDARY. MEANWHILE WESTERN NEW YORK SHOULD REMAIN BETWEEN
THESE TWO AREAS THIS MORNING WITH FAIR WEATHER AND HIGH CLOUD
FILTERED SUNSHINE. SOME PATCHY FOG DEVELOPED DURING THE EARLY
MORNING HOURS...BUT THIS SHOULD BURN OFF QUICKLY THROUGH MID-
MORNING. EARLY AFTERNOON HIGHS SHOULD BE FAIRLY SIMILAR TO
YESTERDAY...WITH HIGHS AGAIN IN THE LOWER TO MID 80S.
AFTER THIS...A UPPER LEVEL SHORTWAVE WILL TRACK ACROSS ONTARIO AND
THEN INTO QUEBEC THIS EVENING. THIS WILL PUSH A COLD FRONT ACROSS
OUR REGION LATE AFTERNOON. IN GENERAL...THE FRONTAL BOUNDARY
SHOULD PROVIDE ENOUGH OF A FOCUS TO BRING MEASURABLE PRECIPITATION
TO THE MAJORITY OF THE REGION. A MODEST SW FLOW OF 25 KTS AT 925
MB WILL INITIALLY PROVIDE SOME LAKE SHADOWING NE OF THE
LAKES...AND IT IS ALSO LIKELY TO DELAY THE FRONTAL PASSAGE A BIT.
HOWEVER...GIVEN FAIRLY WARM LAKE TEMPERATURES AND THE MODEST MID-
LEVEL FLOW...THE FRONTAL BOUNDARY WILL EVENTUALLY WIN OUT AND
BRING A ROUND OF SHOWERS AND THUNDERSTORMS TO MOST. THIS IS IDEA
IS GENERALLY SHOWN BY CONSENSUS OF THE 00Z RUNS OF THE NAM/RGEM/GFS
AND 03Z SREF ENSEMBLE GUIDANCE.
RECENT RUNS OF THE HRRR SUPPORT A SLIGHTLY SLOWER TIMING WITH THE
FRONT...AS IT INITIALLY STRUGGLES TO PUSH THROUGH THE SW FLOW UP
THE LAKES. NAM/GFS CAPES OF 1000 J/KG SHOULD BE ENOUGH INSTABILITY
FOR THE FRONT TO TAP INTO...WITH SHOWERS LIKELY TO DROP FROM NW TO
SE. THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL BE IN THE
200 PM TO 800 PM TIMEFRAME.
SEVERE WEATHER POTENTIAL REMAINS LIMITED WITH 850 MB WINDS OF 25
KNOTS RESULTING IN WEAK TO MODEST SHEAR. HOWEVER...THE NORTH
COUNTRY IS CLOSEST TO THE SHORTWAVE AND WITH SEVERAL RUNS OF THE
HRRR DEVELOPING A LINE ACROSS QUEBEC WILL ADD A MENTION OF GUSTY
WINDS. OTHERWISE...LOCALIZED PULSE STORMS CANNOT BE RULED
OUT...BUT HAVE A LOW PROBABILITY OF OCCURRENCE AND ANY GIVEN
LOCATION. NAM/GFS FORECAST PWATS TO RISE TO 1.50 TO 1.75 INCHES
WHICH COULD POSE A THREAT FOR LOCALIZED HEAVY RAINS IF STORMS
STALL ALONG LAKE BREEZE BOUNDARIES. AT THIS TIME...HRRR RUNS AND
MOST MODEL GUIDANCE SUGGEST A BOUNDARY PROGRESSIVE ENOUGH TO KEEP
HEAVY RAINS FROM FOCUSING ON ANY ONE LOCATION.
THE FRONTAL BOUNDARY WILL PUSH SOUTH OF OUR REGION THIS
EVENING...WITH ANY LINGERING SHOWERS LIKELY TO DROP SOUTH AND EAST
OF THE REGION BY LATE EVENING. OTHERWISE...EXPECT CLEARING SKIES AND
NOTABLY COOLER TEMPERATURES. LOWS SHOULD DROP INTO THE UPPER 50S TO
AROUND 60.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
CANADIAN SOURCED HIGH PRESSURE WILL BUILD FROM THE GREAT LAKES ACROSS
NEW YORK FOR FRIDAY AND SATURDAY. THIS WILL BRING A RETURN TO MORE
COMFORTABLE TEMPERATURES WITH SUNNY AND DRY WEATHER. DESPITE THE
SUNSHINE...A LIGHT NORTHERLY FLOW AND 850MB TEMPERATURES RUNNING
AROUND +10C WILL KEEP DAYTIME HIGHS IN THE LOW TO MID 70S. THE DRY
AIR WITH CLEAR SKIES AND LIGHT WINDS AT NIGHT WILL BE IDEAL FOR
RADIATIONAL COOLING BRINGING COOLER OVERNIGHT TEMPERATURES THAN THE
WARMTH AND HUMIDITY WE HAVE SEEN OF RECENT NIGHTS. LOWS WILL FALL
INTO THE MID TO LOW 50S WITH SOME UPPER 40S WELL INLAND FROM THE
LAKES. LIMITED SURFACE MOISTURE MAY GET TRAPPED BELOW NOCTURNAL
INVERSIONS EACH NIGHT WITH PATCHY GROUND AND VALLEY FOG POSSIBLE
AWAY FROM URBAN LOCATIONS ACROSS LOW LYING AREAS AND NEAR SMALLER
LAKES AND STREAMS.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
BY SUNDAY SURFACE HIGH PRESSURE WILL BE DRIFTING OFF THE EASTERN
SEABOARD...ALLOWING A SOUTHWEST RETURN FLOW TO BEGIN MODERATING
TEMPERATURES. AFTER A COOL MORNING...EXPECT HIGHS TO GET TO WITHIN A
FEW DEGREES OF AVERAGE FOR LATE AUGUST. THERE WILL STILL BE A GOOD
AMOUNT OF SUNSHINE WITH NOTHING MORE THAN SOME HIGH CIRRUS DRIFTING
IN FROM AN UPSTREAM WARM FRONTAL BOUNDARY.
SUNDAY NIGHT THROUGH THE FIRST HALF OF NEXT WEEK THE PATTERN WILL
BECOME MORE ACTIVE. A STRONG RIDGE WILL REMAIN IN PLACE OVER THE
CENTRAL PLAINS AND EXPAND SLOWLY NORTH AND EAST TOWARDS THE REGION.
THE NORTHERN RING OF THE RIDGE WILL BECOME MORE ACTIVE WITH A PARADE
OF PACIFIC SHORTWAVES AND SOUTHWEST MONSOONAL CONVECTION DRIVEN
SHORTWAVES PROPAGATING ALONG THE US/CANADIAN BORDER. A WARM FRONT
WILL LIFT NORTHEAST ACROSS THE REGION LATE SUNDAY NIGHT AND
MONDAY...THEN THE BOUNDARY WILL STALL NEARBY FROM THE UPPER LAKES TO
NORTHERN NY. THE SHORTWAVES AND STALLED FRONTAL BOUNDARY WILL
PROVIDE A CORRIDOR TO FOCUS SEVERAL ROUNDS OF SHOWERS AND
CONVECTION...BUT TIMING AT THIS TIME RANGE WILL BE DIFFICULT. FOR
NOW HAVE FOLLOWED ECMWF TIMING CLOSELY WHICH ALLOWS A FORECAST CLOSE
TO PREVIOUS CONTINUITY...WITH CHANCE POPS SUNDAY NIGHT THROUGH
MONDAY NIGHT THEN AGAIN ON WEDNESDAY. THIS MAY NEED TO BE ADJUSTED
IN COMING DAYS WITH FURTHER MODEL TIMING ADJUSTMENTS EXPECTED.
AS LONG AS CONVECTION DOES NOT BECOME TOO WIDESPREAD OR LONG IN
DURATION...TEMPERATURES WILL CREEP ABOVE AVERAGE AGAIN NEXT WEEK AND
HUMIDITY WILL BE ON THE RISE.
&&
.AVIATION /11Z THURSDAY THROUGH MONDAY/...
THROUGH THIS MORNING. EXPECT VFR CONDITIONS OUTSIDE OF SOME LIGHT
FOG WHICH SHOULD BURN OFF RATHER QUICKLY THROUGH MID-MORNING. A
FRONTAL BOUNDARY WILL DROP ACROSS THE REGION LATE THIS AFTERNOON.
THIS WILL LIKELY BRING SHOWERS TO MOST TAF LOCATIONS...WITH A
CHANCE OF THUNDERSTORMS. BRIEF PERIODS OF IFR OR LOWER CONDITIONS
ARE POSSIBLE IN THUNDERSTORMS DUE TO HEAVY RAIN. THE FRONT WILL
PUSH SOUTH OF THE REGION THIS EVENING...WITH A RETURN TO VFR
CONDITIONS. FOG MAY DEVELOP BEHIND THE FRONT...ESPECIALLY AT JHW.
OUTLOOK...
FRIDAY THROUGH SUNDAY...VFR.
MONDAY...MAINLY VFR WITH A CHANCE OF SHOWERS/THUNDERSTORMS.
&&
.MARINE...
WINDS WILL INCREASE TODAY...BUT SHOULD BE STRONGER ONSHORE THAN
THE WATERS DUE TO LAKE BREEZE ENHANCEMENT. EVEN STILL...EXPECT SW
WINDS TO BUILD WAVES UP TO 4 FEET ON LAKE ERIE...WHICH IS JUST SHY
OF SMALL CRAFT CRITERIA. THEN WINDS WILL SHIFT TO THE NW BEHIND
THE FRONT...AND GENERALLY RUN IN THE 10 TO 20 KNOT RANGE TONIGHT.
THIS WILL CAUSE WAVES TO INCREASE ON THE SOUTH SHORES OF LAKE
ONTARIO...WITH CONDITIONS AGAIN LIKELY TO APPROACH BUT NOT MEET
SMALL CRAFT ADVISORY CRITERIA.
AFTER THIS...HIGH PRESSURE WILL BUILD IN...WITH GENERALLY LIGHT
WINDS AND GOOD BOATING CONDITIONS EXPECTED FRIDAY THROUGH SUNDAY.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...SMITH
LONG TERM...HITCHCOCK
AVIATION...APFFEL
MARINE...APFFEL/SMITH
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1104 AM EDT THU AUG 22 2013
.SYNOPSIS...
MID/UPPER LEVEL DISTURBANCE CROSSES TODAY. COLD FRONT
TONIGHT AND FRIDAY. HIGH PRESSURE FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
11 AM UPDATE. CONCERNS FOR MORE ORGANIZED CONVECTION THIS AFTERNOON
AND TONIGHT WITH PW.S AROUND 2 INCHES...HAS PROMPTED A FLASH FLOOD
WATCH FOR MUCH OF WEST VIRGINIA FROM 2 PM THIS AFTERNOON THRU 11 AM
FRIDAY. THE AREAS OF CONCERN ARE GENERALLY THOSE AREAS THAT RECEIVED
POCKETS OF HEAVY RAIN AND WATER ISSUES LAST EVENING. SEE BELOW FOR
AREA SPECIFICS.
PREVIOUS DISCUSSION BELOW...
UPR LOW SHOULD BE E OF AREA BY MORNING. WILL KEEP LOW POPS THRU
MORNING TO ACCOUNT FOR ANY POP UP SHRA WITH LIFT WITH UPR LVL SYS.
ATTENTION THEN TURNS UPSTREAM FOR POTENTIALLY ACTIVE AFTN ACROSS THE
AREA. MDLS HAVE BEEN FAIRLY CONSISTENT IN PAST 24 HRS ON BRINGING
DOWN A DISTURBANCE AND PREFRONTAL LINE OF CONVECTION LATER TDY. THIS
SHOWS UP NICELY IN THE H7-H5 LYR OMEGA FIELDS ALONG WITH MID LVL
PVA. THE QUESTION IS HOW MUCH INSTABILITY CAN BE REALIZED WITH
POTENTIAL FOR DEBRIS CLDS TO WORK IN HERE THIS MORNING. WILL HEDGE
THAT BULK OF DEBRIS CLDS WILL STAY W OF AREA...MORE INTO KY...AND
DISSIPATE AS RUC SUGGESTS. WILL LEAN ON FASTER NAM/WRF MDLS FOR
TIMING THIS AFTN...ALTHOUGH EVEN SLOWER GFS NOT TOO FAR BEHIND. WILL
BRING IN LKLY POPS INTO SE OH 17 TO 19Z AND LOWLANDS/NE KY 19 TO
21Z...INTO MTNS/SW VA 22 TO 00Z. THERE IS SOME CONCERN THIS TRIES TO
SLOW DOWN A BIT ACROSS S ZONES...IE SW VA...THIS EVE.
OVERALL...THOUGH...THIS SHOULD MOVE RIGHT ALONG WITH STORM MOTIONS
15 TO 20 KTS.
AS FOR WATER CONCERNS...THERE WERE SOME PLACES THAT
GOT A GOOD HIT YESTERDAY...MAINLY ALONG I64 CORRIDOR FROM HTS TO
CRW. PWATS SURGE RIGHT BACK UP NEAR 2 INCHES WITH THIS FEATURE
WHICH MEANS DOWNPOURS A GOOD BET. ELECTED TO CODE UP A HVY RA
MENTION IN WX GRIDS WITH CONVECTION. WITH DECENT STORM MOTIONS AND
MOVEMENT LESS CONDUCIVE TO TRAINING...WILL FORGO A WATCH ATTM BUT
PUT A MENTION IN HWO FOR POSSIBLE STREET FLOODING AND LOW LYING
AREA CONCERNS.
ASSUMING MDLS ARE CORRECT...SHOULD SEE A LULL THIS EVE BEFORE SFC
FRONT APPROACHES. MDLS SEEM TO PLACE FRONT ALONG OH RVR BY END OF
NEAR TERM. UNCLEAR ON HOW ACTIVE ACTUAL BOUNDARY WILL BE GIVEN
NIGHT TIME HRS. HOWEVER...WITH DECENT LIFT SHOWN...WILL CODE UP
SOME HIGH CHC POPS OVERNIGHT AND KEEP A SMALL THUNDER THREAT IN.
CANT RULE OUT A FEW SVR CELLS THIS AFTN...MAINLY WIND. BUT
AGAIN...DOWNPOURS BIGGEST ISSUE.
FOR TEMPS...HEDGED TOWARD LAMP GUIDANCE ONCE AGAIN GIVEN ITS
RECENT PERFORMANCE. THIS RESULTED IN MINOR TWEAKS HERE AND THERE
FROM PREV FCST. GENERALLY LOW TO MID 80S ONCE AGAIN. LEANED ON
WARM SIDE TONIGHT GIVEN ABUNDANCE OF MOISTURE ABOUT THE AREA AND
SHRA THREAT.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
MODELS STILL HAVE SOME TIMING DIFFERENCES ON FRIDAY WITH THE COLD
FRONT AND ASSOCIATED MOISTURE. NAM CONTINUES TO BE THE SLOWEST WHILE
THE CANADIAN IS THE FASTEST. GFS AND ECMWF LIE IN THE MIDDLE. WITH
NO OBVIOUS REASON WHY ONE MODEL WOULD BE BETTER THAN THE
OTHER...WILL CONTINUE TO RUN A MIDDLE OF THE ROAD SOLUTION.
HIGH PRESSURE THEN TAKES OVER FOR THE WEEKEND...PROVIDING DRY
WEATHER AND LOW HUMIDITY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
UPPER RIDGE BUILDING OVER THE SOUTHERN PLAINS THROUGH THE LONG TERM
FORECAST. THE CENTER OF THE 500MB HIGH GENERALLY DRIFTS AROUND OVER
KS/OK/MO...WHICH KEEPS OUR REGION IN NW FLOW ALOFT...WITH SEVERAL
RIPPLES DROPPING THROUGH. TIMING/LOCATION OF EACH INDIVIDUAL WAVE
VARY BETWEEN GFS/ECMWF. SOME LOW LEVEL MOISTURE SHOULD BE AVAILABLE
WITH SE SURFACE FLOW...BUT JUST HOW MUCH WILL DEPEND ON WHERE
SURFACE HIGH IS. IF IT STAYS OVER THE SE STATES...WE WOULD GET AT
LEAST SOME MOISTURE ADVECTION FROM THE GULF...WHILE IF IT THE
SURFACE HIGH DRIFTS FARTHER WEST AS THE ECMWF HINTS...THAT RICHER
MOISTURE FLOW COULD GET CUT OF. DUE TO THIS UNCERTAINTY...STAYED
PRETTY CLOSE TO WPC GUIDANCE. WITH 500 HEIGHTS OVER 590DAM...LOOKS
LIKE A WARM STRETCH...WITH LOWLAND HIGHS IN THE UPPER 80S AND EVEN
SOME 90S NEXT WEEK. COULD ACTUALLY BE WARMER IF WE DO NOT HAVE THE
GOOD MOISTURE FLOW...AS THE DRIER AIR WOULD BE EASIER TO WARM.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
15Z THURSDAY THRU 15Z FRIDAY...
MORNING IFR/MVFR STRATUS LIFTS TO VFR CEILINGS BY 17Z. EXPECT UPR
DISTURBANCE TO MAKE A RUN THRU AREA AFTER 18Z FROM NW...WELL AHEAD
OF SFC FRONT. AS SUCH...HAVE A PREDOMINATE SHRA/VCTS IN TAFS FOR
EXPECTED CONVECTIVE LINE IN AFTN WHICH WILL DROP SOUTHEAST. KEPT
PREDOMINATE VFR...BUT LOCALLY LOWER IN HEAVIER SHOWERS AND STORMS.
THINGS MAY QUIET DOWN AFTER 03Z TONIGHT UNTIL SFC FRONT APPROACHES
WITH PERHAPS ANOTHER ROUND OF SHRA LATER TONIGHT INTO FRIDAY
MORNING. NOT EXPECTING MUCH IN WAY OF DENSE FG TONIGHT WITH
ABUNDANCE OF CLDS ACROSS THE AREA.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING OF CONVECTION THIS AFTN MAY VARY A
FEW HRS.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
EDT 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 12Z FRIDAY...
AREAS OF IFR IN DENSE FOG/LOW STRATUS MOST MORNINGS THIS
WEEK...ESPECIALLY ALONG THE RIVERS. IFR IN SHOWERS AND THUNDERSTORMS
FRIDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR WVZ006>011-
013>020-026>032-038>040-047.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/JMV/30
NEAR TERM...JMV/30
SHORT TERM...RPY
LONG TERM...MZ
AVIATION...JMV/30
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
721 AM EDT THU AUG 22 2013
.SYNOPSIS...
A COLD FRONT OVER MICHIGAN WILL MOVE ACROSS THE AREA THIS
AFTERNOON AND EVENING. HIGH PRESSURE THEN BUILDS BACK INTO THE
REGION FOR FRIDAY INTO THE WEEKEND. ANOTHER WEATHER SYSTEM WILL
AFFECT THE AREA EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED TO TWEAKS THE POPS A LITTLE WITH AN AREA OF SHOWERS AND
POSSIBLE THUNDER DEVELOPING NORTH OF THE ISLANDS IN ONTARIO.
OTHERWISE THE FORECAST LOOKS GOOD...STILL SOME QUESTION HOW MUCH
ACTIVITY WILL OCCUR ALONG THE LAKE SHORE.
PREVIOUS DISCUSSION...
AN UPPER TROF IS MOVING OUT OF EXTREME EASTERN OHIO EARLY THIS
MORNING...IT IS TAKING THE CLOUDS WITH IT. A COLD FRONT WILL BE
MOVING THROUGH THE FORECAST AREA THIS AFTERNOON AND EVENING...THE
ISSUE/DILEMMA IS THE TIMING OF THUNDERSTORMS AND WILL THEY BE
SEVERE. AT 330 AM EDT THE AREA OF SHOWERS AND THUNDERSTORMS OVER
MICHIGAN WAS WEAKENING. MY PLAN BASED ON THE HRRR AND SOME OF THE
MODELS IS TO HAVE A CHANCE OF SHOWERS THIS AM OVER NORTHWEST OHIO
AND THEN A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS ESPECIALLY
INLAND THIS AFTERNOON AS THE FRONT MOVES IN AND WE GET SOME
HEATING. IT IS STILL NOT CLEAR IF ALL THE THUNDERSTORMS WILL
DEVELOP OVER NORTHERN OHIO AND NW PA OR WILL SOME THUNDERSTORMS
MOVE IN FROM MICHIGAN. AT THIS TIME GOING WITH NOT MUCH MOVING IN
FROM MICHIGAN SO KEEPING MOST OF THE ACTIVITY OVER THE INLAND
AREAS AND SCATTERED ALONG THE LAKE SHORE.
THE HIGHS ARE TOUGH TODAY IT ALL DEPENDS ON THE CLOUD COVER. I THINK
WE SHOULD HAVE SOME SUNSHINE. WENT CLOSE TO THE WARMER GUIDANCE.
ALSO THE CLOUD COVER WILL DETERMINE WHETHER SOME OF THE
THUNDERSTORMS COULD BE SEVERE. SINCE THE CLOUDS WITH THE COMPLEX
OVER MICHIGAN ARE DECREASING WE SHOULD GET SOME CAPE SO ISOLATED
SEVERE THUNDERSTORMS ARE POSSIBLE. THIS WILL BE MENTIONED IN THE
HAZARDOUS WEATHER OUTLOOK.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
HIGH PRESSURE IS BUILDING TONIGHT AS THE COLD FRONT WILL BE ACROSS
THE INLAND AREAS BY 6 PM EDT. SOME SHOWERS AND THUNDERSTORMS WILL
LINGER EARLY IN THE EVENING BEFORE IT DRIES OUT. SOME OF THE MODELS
LIKE THE NAM AND THE CANADIAN MODEL TRY TO HANG THE COLD FRONT UP
OVER LAKE ERIE THIS EVENING. AT THIS TIME LEANING TOWARD THE GFS AND
ECMWF WHICH PUSHES THE FRONT THROUGH. THIS SEEMS REASONABLE BASED
ON WHAT IS GOING ON UPSTREAM AND THE STRENGTH OF THE HIGH.
A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE AREA FRIDAY AND BE IN
CONTROL SATURDAY AND THEN SLIDE SOUTHEAST ON SUNDAY. AT THIS TIME A
DRY FORECAST WITH BELOW NORMAL TEMPERATURES FOR FRIDAY AND SATURDAY
AND THEN RECOVERING ON SUNDAY BACK TO NORMAL AS THE RIDGE WEAKENS
AND A SOUTHWEST FLOW DEVELOPS AGAIN. USED A BLEND OF GUIDANCE FOR
THE TEMPERATURES.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
BIG BUBBLE FINALLY PUSHES EAST IN THE UPPER LEVEL PATTERN. THE
PERSISTENT UPPER LEVEL RIDGE OVER THE WESTERN UNITED STATES WILL
COVER THE ENTIRE UNITED STATES AND BE CENTERED OVER THE MISSISSIPPI
RIVER VALLEY THROUGH MUCH OF THE EXTENDED FORECAST PERIOD.
ACTUALLY...THE LARGE UPPER LEVEL HIGH PRESSURE CENTER BUILDS OVER
THIS REGION DURING THE PERIOD HELPING TO STRENGTHEN THE CAUSE FOR
WARMER RETURN BACK TO SUMMER WEATHER.
THE ONLY FLY IN THE OINTMENT IS THE FACT THAT THE LOCAL AREA REMAINS
ON THE UPPER NORTHEAST PORTION OF THE RIDGE ALLOWING A FEW
SHORTWAVES TO DIVE DOWN ACROSS THE REGION AND BRING WITH IT A SUPPLY
OF MOISTURE AND THE THREAT FOR SHOWERS AND THUNDERSTORMS. MOISTURE
MAY BE LIMITED WITH THESE FEATURES AS THEY WILL NEED TO TRAVERSE
OVER A LARGE LAND MASS BEFORE ARRIVING HERE. SO WILL KEEP THE
MENTION OF SHOWERS AND THUNDERSTORMS JUST ABOUT EACH PERIOD.
AS MENTIONED ABOVE...FAIRLY STRONG WARM AIR ADVECTION WILL RETURN TO
THE FORECAST AREA DURING THE EXTENDED PERIODS. POTENTIAL EXISTS TO
SEE 90 DEGREES...ESPECIALLY IN THE WESTERN HALF OF THE FORECAST AREA
WHERE IT IS CLOSER TO THE UPPER LEVEL RIDGE. SOME SHOWER ACTIVITY IN
THE EAST MAY HELP KEEP TEMPERATURES OUT OF THE 90S.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
THE BIG QUESTION IS WHERE WILL THE SHOWERS AND THUNDERSTORMS
DEVELOP THIS MORNING. NEARLY ALL OF THE ACTIVITY THAT WAS OVER
MICHIGAN VIRTUALLY DIED OUT. NEW STUFF DEVELOPED AND IS NOW
WORKING ITS WAY SOUTHEAST ACROSS WESTERN LAKE ERIE. WILL THE
STABILITY OF THE LAKE REDUCE THE SHOWERS OR WILL THEY SURVIVE AS
THEY MOVE SOUTHEAST. LATEST ANALYSIS AND GUIDANCE SUGGESTS THE
POSSIBILITY OF MORE SHOWERS AND WEAK THUNDERSTORMS WILL DEVELOP
ALONG A NARROW BAND FROM WESTERN LAKE ERIE ACROSS NORTHWEST OHIO
THIS MORNING. THIS ACTIVITY WILL MOVE SOUTHEAST TODAY. SINCE THERE
IS SO MUCH UNCERTAINTY ON WHERE THE LINE WILL BE AND HOW NUMEROUS
THE SHOWERS WILL BE...WILL JUST MENTION VCSH OR VCTS. AFTER THINGS
SETTLE DOWN LATER TODAY...RETURN BACK TO VFR WITH EXCEPTION OF
SOME FOG IN THE WEST. WINDS SHIFT AROUND TO WEST NORTHWEST FOR THE
AFTERNOON AND OVERNIGHT HOURS.
OUTLOOK...NON-VFR IN FOG/MIST FRIDAY NIGHT. MVFR POSSIBLE MONDAY.
&&
.MARINE...
WINDS WILL BE ON THE INCREASE ACROSS THE LAKE TODAY AHEAD OF THE
COLD FRONT. FRONT LOOKS LIKE IT SHOULD SLIP SOUTH OF THE AREA BUT A
REINFORCING COLD FRONT STALLS JUST NORTH OF THE LAKE TODAY AND THEN
GRADUALLY SHIFTS SOUTH OF THE LAKE TONIGHT. MAY NEED A SMALL CRAFT
ADVISORY FOR A PERIOD LATE TONIGHT INTO FRIDAY...ESPECIALLY FROM
ABOUT CONNEAUT WEST. WINDS DIMINISH FAIRLY QUICKLY ON FRIDAY
ALLOWING WAVES TO SUBSIDE TO A FOOT OR LESS BY EVENING. A SLIGHT
INCREASE IN WAVES EXPECTED FRIDAY NIGHT WITH A LIGHT CHOP INTO EARLY
SATURDAY MORNING. THEN...LAKE SETTLES NICELY BY SUNDAY INTO SUNDAY
NIGHT WITH A SLIGHT INCREASE MONDAY WITH 1 TO 3 FOOTERS MAINLY NORTH
2/3RD`S OF THE LAKE.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...LOMBARDY
AVIATION...LOMBARDY
MARINE...LOMBARDY
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
647 AM EDT THU AUG 22 2013
.SYNOPSIS...
A COLD FRONT OVER MICHIGAN WILL MOVE ACROSS THE AREA THIS
AFTERNOON AND EVENING. HIGH PRESSURE THEN BUILDS BACK INTO THE
REGION FOR FRIDAY INTO THE WEEKEND. ANOTHER WEATHER SYSTEM WILL
AFFECT THE AREA EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED TO TWEAKS THE POPS A LITTLE WITH AN AREA OF SHOWERS AND
POSSIBLE THUNDER DEVELOPING NORTH OF THE ISLANDS IN ONTARIO.
OTHERWISE THE FORECAST LOOKS GOOD...STILL SOME QUESTION HOW MUCH
ACTIVITY WILL OCCUR ALONG THE LAKESHORE.
PREVIOUS DISCUSSION...
AN UPPER TROF IS MOVING OUT OF EXTREME EASTERN OHIO EARLY THIS
MORNING...IT IS TAKING THE CLOUDS WITH IT. A COLD FRONT WILL BE
MOVING THROUGH THE FORECAST AREA THIS AFTERNOON AND EVENING...THE
ISSUE/DILEMMA IS THE TIMING OF THUNDERSTORMS AND WILL THEY BE
SEVERE. AT 330 AM EDT THE AREA OF SHOWERS AND THUNDERSTORMS OVER
MICHIGAN WAS WEAKENING. MY PLAN BASED ON THE HRRR AND SOME OF THE
MODELS IS TO HAVE A CHANCE OF SHOWERS THIS AM OVER NORTHWEST OHIO
AND THEN A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS ESPECIALLY
INLAND THIS AFTERNOON AS THE FRONT MOVES IN AND WE GET SOME
HEATING. IT IS STILL NOT CLEAR IF ALL THE THUNDERSTORMS WILL
DEVELOP OVER NORTHERN OHIO AND NW PA OR WILL SOME THUNDERSTORMS
MOVE IN FROM MICHIGAN. AT THIS TIME GOING WITH NOT MUCH MOVING IN
FROM MICHIGAN SO KEEPING MOST OF THE ACTIVITY OVER THE INLAND
AREAS AND SCATTERED ALONG THE LAKESHORE.
THE HIGHS ARE TOUGH TODAY IT ALL DEPENDS ON THE CLOUD COVER. I THINK
WE SHOULD HAVE SOME SUNSHINE. WENT CLOSE TO THE WARMER GUIDANCE.
ALSO THE CLOUD COVER WILL DETERMINE WHETHER SOME OF THE
THUNDERSTORMS COULD BE SEVERE. SINCE THE CLOUDS WITH THE COMPLEX
OVER MICHIGAN ARE DECREASING WE SHOULD GET SOME CAPE SO ISOLATED
SEVERE THUNDERSTORMS ARE POSSIBLE. THIS WILL BE MENTIONED IN THE
HAZARDOUS WEATHER OUTLOOK.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
HIGH PRESSURE IS BUILDING TONIGHT AS THE COLD FRONT WILL BE ACROSS
THE INLAND AREAS BY 6 PM EDT. SOME SHOWERS AND THUNDERSTORMS WILL
LINGER EARLY IN THE EVENING BEFORE IT DRIES OUT. SOME OF THE MODELS
LIKE THE NAM AND THE CANADIAN MODEL TRY TO HANG THE COLD FRONT UP
OVER LAKE ERIE THIS EVENING. AT THIS TIME LEANING TOWARD THE GFS AND
ECMWF WHICH PUSHES THE FRONT THROUGH. THIS SEEMS REASONABLE BASED
ON WHAT IS GOING ON UPSTREAM AND THE STRENGTH OF THE HIGH.
A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE AREA FRIDAY AND BE IN
CONTROL SATURDAY AND THEN SLIDE SOUTHEAST ON SUNDAY. AT THIS TIME A
DRY FORECAST WITH BELOW NORMAL TEMPERATURES FOR FRIDAY AND SATURDAY
AND THEN RECOVERING ON SUNDAY BACK TO NORMAL AS THE RIDGE WEAKENS
AND A SOUTHWEST FLOW DEVELOPS AGAIN. USED A BLEND OF GUIDANCE FOR
THE TEMPERATURES.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
BIG BUBBLE FINALLY PUSHES EAST IN THE UPPER LEVEL PATTERN. THE
PERSISTENT UPPER LEVEL RIDGE OVER THE WESTERN UNITED STATES WILL
COVER THE ENTIRE UNITED STATES AND BE CENTERED OVER THE MISSISSIPPI
RIVER VALLEY THROUGH MUCH OF THE EXTENDED FORECAST PERIOD.
ACTUALLY...THE LARGE UPPER LEVEL HIGH PRESSURE CENTER BUILDS OVER
THIS REGION DURING THE PERIOD HELPING TO STRENGTHEN THE CAUSE FOR
WARMER RETURN BACK TO SUMMER WEATHER.
THE ONLY FLY IN THE OINTMENT IS THE FACT THAT THE LOCAL AREA REMAINS
ON THE UPPER NORTHEAST PORTION OF THE RIDGE ALLOWING A FEW
SHORTWAVES TO DIVE DOWN ACROSS THE REGION AND BRING WITH IT A SUPPLY
OF MOISTURE AND THE THREAT FOR SHOWERS AND THUNDERSTORMS. MOISTURE
MAY BE LIMITED WITH THESE FEATURES AS THEY WILL NEED TO TRAVERSE
OVER A LARGE LAND MASS BEFORE ARRIVING HERE. SO WILL KEEP THE
MENTION OF SHOWERS AND THUNDERSTORMS JUST ABOUT EACH PERIOD.
AS MENTIONED ABOVE...FAIRLY STRONG WARM AIR ADVECTION WILL RETURN TO
THE FORECAST AREA DURING THE EXTENDED PERIODS. POTENTIAL EXISTS TO
SEE 90 DEGREES...ESPECIALLY IN THE WESTERN HALF OF THE FORECAST AREA
WHERE IT IS CLOSER TO THE UPPER LEVEL RIDGE. SOME SHOWER ACTIVITY IN
THE EAST MAY HELP KEEP TEMPERATURES OUT OF THE 90S.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
A LINE OF CONVECTION CONTINUES TO MOVE SOUTHEAST OUT OF SOUTHERN
LOWER MICHIGAN. THIS ACTIVITY IS JUST AHEAD OF THE COLD FRONT AT
THIS TIME. THE ACTIVITY SHOULD MOVE SOUTHEAST TOWARD TOLEDO AND
FINDLAY BY 12Z THIS MORNING AND THEN SPREAD EAST ACROSS THE REST
OF THE AREA THROUGHOUT THE MORNING. THE OTHER PROBLEM WILL BE FOG
DEVELOPMENT ACROSS THE AREA. WINDS SHOULD HELP KEEP DENSE FOG FROM
DEVELOPING ALL LOCATIONS BUT THERE IS A POSSIBILITY FOR
VISIBILITIES TO DROP TO AROUND 2 MILES AT AKRON CANTON AND
YOUNGSTOWN. CONVECTION MOVES SOUTH AND EAST OF THE AREA THIS
AFTERNOON. THE HOPE IS THAT FRONT DOES NOT STALL OVER THE AREA AND
KEEP A THREAT GOING FOR SHOWERS AND THUNDERSTORMS INTO THE EVENING.
OUTLOOK...NON-VFR IN FOG/MIST LATE TONIGHT AND FRIDAY NIGHT. MVFR
POSSIBLE MONDAY.
&&
.MARINE...
WINDS WILL BE ON THE INCREASE ACROSS THE LAKE TODAY AHEAD OF THE
COLD FRONT. FRONT LOOKS LIKE IT SHOULD SLIP SOUTH OF THE AREA BUT A
REINFORCING COLD FRONT STALLS JUST NORTH OF THE LAKE TODAY AND THEN
GRADUALLY SHIFTS SOUTH OF THE LAKE TONIGHT. MAY NEED A SMALL CRAFT
ADVISORY FOR A PERIOD LATE TONIGHT INTO FRIDAY...ESPECIALLY FROM
ABOUT CONNEAUT WEST. WINDS DIMINISH FAIRLY QUICKLY ON FRIDAY
ALLOWING WAVES TO SUBSIDE TO A FOOT OR LESS BY EVENING. A SLIGHT
INCREASE IN WAVES EXPECTED FRIDAY NIGHT WITH A LIGHT CHOP INTO EARLY
SATURDAY MORNING. THEN...LAKE SETTLES NICELY BY SUNDAY INTO SUNDAY
NIGHT WITH A SLIGHT INCREASE MONDAY WITH 1 TO 3 FOOTERS MAINLY NORTH
2/3RD`S OF THE LAKE.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...LOMBARDY
AVIATION...LOMBARDY
MARINE...LOMBARDY
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
633 AM EDT THU AUG 22 2013
.SYNOPSIS...
MID/UPPER LEVEL DISTURBANCE CROSSES TODAY. COLD FRONT
TONIGHT AND FRIDAY. HIGH PRESSURE FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
630 AM UPDATE...
NO SIGNIFICANT CHANGES THIS MORNING.
PREVIOUS DISCUSSION BELOW...
UPR LOW SHOULD BE E OF AREA BY MORNING. WILL KEEP LOW POPS THRU
MORNING TO ACCOUNT FOR ANY POP UP SHRA WITH LIFT WITH UPR LVL SYS.
ATTENTION THEN TURNS UPSTREAM FOR POTENTIALLY ACTIVE AFTN ACROSS
THE AREA. MDLS HAVE BEEN FAIRLY CONSISTENT IN PAST 24 HRS ON
BRINGING DOWN A DISTURBANCE AND PREFRONTAL LINE OF CONVECTION
LATER TDY. THIS SHOWS UP NICELY IN THE H7-H5 LYR OMEGA FIELDS
ALONG WITH MID LVL PVA. THE QUESTION IS HOW MUCH INSTABILITY CAN
BE REALIZED WITH POTENTIAL FOR DEBRIS CLDS TO WORK IN HERE THIS
MORNING. WILL HEDGE THAT BULK OF DEBRIS CLDS WILL STAY W OF
AREA...MORE INTO KY...AND DISSIPATE AS RUC SUGGESTS. WILL LEAN ON
FASTER NAM/WRF MDLS FOR TIMING THIS AFTN...ALTHOUGH EVEN SLOWER
GFS NOT TOO FAR BEHIND. WILL BRING IN LKLY POPS INTO SE OH 17 TO
19Z AND LOWLANDS/NE KY 19 TO 21Z...INTO MTNS/SW VA 22 TO 00Z.
THERE IS SOME CONCERN THIS TRIES TO SLOW DOWN A BIT ACROSS S
ZONES...IE SW VA...THIS EVE. OVERALL...THOUGH...THIS SHOULD MOVE
RIGHT ALONG WITH STORM MOTIONS 15 TO 20 KTS.
AS FOR WATER CONCERNS...THERE WERE SOME PLACES THAT
GOT A GOOD HIT YESTERDAY...MAINLY ALONG I64 CORRIDOR FROM HTS TO
CRW. PWATS SURGE RIGHT BACK UP NEAR 2 INCHES WITH THIS FEATURE
WHICH MEANS DOWNPOURS A GOOD BET. ELECTED TO CODE UP A HVY RA
MENTION IN WX GRIDS WITH CONVECTION. WITH DECENT STORM MOTIONS AND
MOVEMENT LESS CONDUCIVE TO TRAINING...WILL FORGO A WATCH ATTM BUT
PUT A MENTION IN HWO FOR POSSIBLE STREET FLOODING AND LOW LYING
AREA CONCERNS.
ASSUMING MDLS ARE CORRECT...SHOULD SEE A LULL THIS EVE BEFORE SFC
FRONT APPROACHES. MDLS SEEM TO PLACE FRONT ALONG OH RVR BY END OF
NEAR TERM. UNCLEAR ON HOW ACTIVE ACTUAL BOUNDARY WILL BE GIVEN
NIGHT TIME HRS. HOWEVER...WITH DECENT LIFT SHOWN...WILL CODE UP
SOME HIGH CHC POPS OVERNIGHT AND KEEP A SMALL THUNDER THREAT IN.
CANT RULE OUT A FEW SVR CELLS THIS AFTN...MAINLY WIND. BUT
AGAIN...DOWNPOURS BIGGEST ISSUE.
FOR TEMPS...HEDGED TOWARD LAMP GUIDANCE ONCE AGAIN GIVEN ITS
RECENT PERFORMANCE. THIS RESULTED IN MINOR TWEAKS HERE AND THERE
FROM PREV FCST. GENERALLY LOW TO MID 80S ONCE AGAIN. LEANED ON
WARM SIDE TONIGHT GIVEN ABUNDANCE OF MOISTURE ABOUT THE AREA AND
SHRA THREAT.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
MODELS STILL HAVE SOME TIMING DIFFERENCES ON FRIDAY WITH THE COLD
FRONT AND ASSOCIATED MOISTURE. NAM CONTINUES TO BE THE SLOWEST WHILE
THE CANADIAN IS THE FASTEST. GFS AND ECMWF LIE IN THE MIDDLE. WITH
NO OBVIOUS REASON WHY ONE MODEL WOULD BE BETTER THAN THE
OTHER...WILL CONTINUE TO RUN A MIDDLE OF THE ROAD SOLUTION.
HIGH PRESSURE THEN TAKES OVER FOR THE WEEKEND...PROVIDING DRY
WEATHER AND LOW HUMIDITY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
UPPER RIDGE BUILDING OVER THE SOUTHERN PLAINS THROUGH THE LONG TERM
FORECAST. THE CENTER OF THE 500MB HIGH GENERALLY DRIFTS AROUND OVER
KS/OK/MO...WHICH KEEPS OUR REGION IN NW FLOW ALOFT...WITH SEVERAL
RIPPLES DROPPING THROUGH. TIMING/LOCATION OF EACH INDIVIDUAL WAVE
VARY BETWEEN GFS/ECMWF. SOME LOW LEVEL MOISTURE SHOULD BE AVAILABLE
WITH SE SURFACE FLOW...BUT JUST HOW MUCH WILL DEPEND ON WHERE
SURFACE HIGH IS. IF IT STAYS OVER THE SE STATES...WE WOULD GET AT
LEAST SOME MOISTURE ADVECTION FROM THE GULF...WHILE IF IT THE
SURFACE HIGH DRIFTS FARTHER WEST AS THE ECMWF HINTS...THAT RICHER
MOISTURE FLOW COULD GET CUT OF. DUE TO THIS UNCERTAINTY...STAYED
PRETTY CLOSE TO WPC GUIDANCE. WITH 500 HEIGHTS OVER 590DAM...LOOKS
LIKE A WARM STRETCH...WITH LOWLAND HIGHS IN THE UPPER 80S AND EVEN
SOME 90S NEXT WEEK. COULD ACTUALLY BE WARMER IF WE DO NOT HAVE THE
GOOD MOISTURE FLOW...AS THE DRIER AIR WOULD BE EASIER TO WARM.
&&
.AVIATION /10Z THURSDAY THROUGH MONDAY/...
12Z THURSDAY THRU 12Z FRIDAY...
UPR S/W TROF PUSHES E OF AREA AFTER 13Z. ISOLD SHRA THREAT THRU
MORNING...BUT CHC NOT GREAT ENOUGH TO INCLUDE IN TAFS.
FG LIFTS AFTER 12Z FOR A RETURN TO VFR CONDITIONS. ANY MORNING
STRATUS SHOULD SCT OUT BY 14Z. HAVE SOME CU FORMING BY LATE
MORNING WITH AREA IN BETWEEN WX SYS. EXPECT UPR DISTURBANCE TO
MAKE A RUN THRU AREA AFTER 18Z FROM NW...WELL AHEAD OF SFC FRONT.
AS SUCH...HAVE A PREDOMINATE SHRA/VCTS IN TAFS FOR EXPECTED
CONVECTIVE LINE IN AFTN. KEPT PREDOMINATE VFR THOUGH GIVEN AT THIS
RANGE.
THINGS MAY QUIET DOWN AFTER 03Z TONIGHT UNTIL SFC FRONT APPROACHES
WITH PERHAPS ANOTHER ROUND OF SHRA. NOT EXPECTING MUCH IN WAY OF
DENSE FG TONIGHT WITH ABUNDANCE OF CLDS ACROSS THE AREA.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING OF CONVECTION THIS AFTN MAY VARY A
FEW HRS.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
EDT 1HRLY 07 08 09 10 11 12 13 14 15 16 17 18
CRW CONSISTENCY L M H H H H H H H H H H
HTS CONSISTENCY M H H H H H H H H H H H
BKW CONSISTENCY L L L H H H H H H H H H
EKN CONSISTENCY L M H H H H H H H H H H
PKB CONSISTENCY L H H H H H H H H H H H
CKB CONSISTENCY M H H H H H H H H H H H
AFTER 12Z FRIDAY...
AREAS OF IFR IN DENSE FOG/LOW STRATUS MOST MORNINGS THIS
WEEK...ESPECIALLY ALONG THE RIVERS. IFR IN SHOWERS AND THUNDERSTORMS
FRIDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30
NEAR TERM...30
SHORT TERM...RPY
LONG TERM...MZ
AVIATION...30
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
759 AM EDT THU AUG 22 2013
.SYNOPSIS...
AN UPPER LOW...CENTERED OVER THE LAUREL HIGHLANDS...WILL DRIFT
ACROSS THE SOUTHERN TIER OF PENNSYLVANIA THIS MORNING. WEAK RIDGING
IN THE WAKE OF THIS LOW WILL BE OVER THE REGION DURING THE MIDDAY
AND AFTERNOON HOURS...ACCOMPANIED BY GENERALLY FAIR WEATHER. A COLD
FRONT WILL PUSH SOUTHEAST ACROSS THE REGION LATE THURSDAY INTO EARLY
FRIDAY...FOLLOWED BY CANADIAN HIGH PRESSURE.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
REGIONAL IR SATELLITE AND RADAR LOOP AT 0815Z SHOWS EXPANDING
COVERAGE OF SHOWERS AND A FEW TSRA FROM THE LAUREL HIGHLANDS...EAST
TO THE LOWER SUSQ VALLEY. THIS CONVECTION WAS OCCURRING WITHIN A
REGION OF MDTLY STRONG UPPER DIFFLUENCE AND DIFFERENTIAL PVA JUST
AHEAD OF A SLOW-MOVING UPPER LOW. ALSO AIDING THIS CONVECTION WAS
THE VERY JUICY AIRMASS WITH LAYER PWATS IN THE 1.5-2 INCH
RANGE...ALONG WITH STRENGTHENING 850-700 MB FRONTOGENESIS.
LATEST HRRR AND RUC CONTINUES TO PAINT LIGHT TO MODERATE RAINFALL
AMOUNTS OVER THE NEXT SEVERAL HOURS ACROSS APPROXIMATELY THE
SOUTHERN 1/3 TO 1/2 OF THE CWA AS THE UPPER LOW TRACKS SLOWLY EAST
AND PROVIDES LIFT OF THE VERY MOIST AND UNSTABLE AIR. MOST OF THE
SHOWERS AND EMBEDDED TSRA WILL BE NEAR AND JUST TO THE SOUTH OF A
LINE FROM KAOO TO KSEG AND KAVP...BEFORE FOCUSING OVER THE ECENT
MTNS /SCHUYLKILL CTY AND VCNTY/ BETWEEN 10-13Z.
SFC DWPTS RANGE FROM THE U60S AND L70S IN THE SOUTH....TO THE UPPER
50S AND LOWER 60S IN THE NORTH...WHERE THE BLYR WILL LIKELY REMAIN
TOO DRY TO SUPPORT ANY CONVECTION.
EXTENSIVE CLOUD COVER AND LOW LVL MOISTURE WILL RESULT IN THE
WARMEST EARLY MORNING IN SOME TIME WITH LOWS RANGING FROM THE UPPER
50S OVR THE N MTNS...TO ARND 70F ACROSS THE LOWER SUSQ VALLEY.
THE REMNANTS OF UPPER LOW SHOULD TAKE UNTIL ARND MIDDAY TO CLEAR THE
ERN...SO WILL CARRY A CHC POPS FOR SHRA/TSRA THERE UNTIL THAT
TIME. RIDGING IN WAKE OF DEPARTING UPPER LOW SHOULD BRING A PERIOD
OF DRY CONDITIONS TO MOST OF CENTRAL PENN ON THURS BEFORE COLD FRONT
FROM THE GLAKES BRINGS ANOTHER THREAT OF CONVECTION LATE IN THE DAY
NW /AND MORE LIKELY BEGINNING THIS EVENING ACROSS THE CENTRAL MTNS/.
A RIBBON OF HIGHER PWATS BETWEEN 1.5 AND 1.75 INCHES AND SLIGHTLY
STEEPER MID-LEVEL LAPSE RATES SHOULD SUPPORT SCT SHRA/TSRA
DEVELOPING ACROSS THE NW MTNS /AHEAD OF A COLD FRONT/ DURING THE MID
TO LATE AFTN...WITH THE CONVECTION SLIDING SE THRU THE REST OF THE
REGION BETWEEN 02-06Z FRIDAY.
HIGH TEMPS THIS AFTERNOON WILL REACH THE MID AND UPPER 80S ACROSS
THE CENTRAL AND SE VALLEYS...AND AROUND 80F OVER THE HIGHER TERRAIN
OF NRN AND WRN PENN.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
AS NOTED ABOVE...THE TIMING OF THE SFC COLD FRONT AND ASSOCIATED
SHRA/TSRA WILL BE DURING THE FIRST HALF OF THE OVERNIGHT HOURS.
POPS WILL DIMINISH STEADILY AFTER MIDNIGHT AND BECOME CONFINED TO
THE SOUTHERN TIER OF THE STATE BEFORE DAYBREAK.
THE MEAN LOW-MID LEVEL FLOW VEERS AROUND TO THE NNW FRIDAY...
ALLOWING DEEP DRYING TO ADVECT INTO THE REGION DURING THE DAY. MAX
TEMPS FRIDAY WILL COOL BY A FEW TO SVRL DEG F COMPARED TO THURSDAY/S.
SFC DEWPOINTS WILL RETREAT BACK TO VERY COMFORTABLE LEVELS IN THE
UPPER 40S /NW/...AND MID 50S /SE/ FRIDAY AFTERNOON...SETTING THE
STAGE FOR A COOL LATE AUGUST NIGHT FRIDAY NIGHT.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
OVERVIEW...THE LATEST MODEL AND ENSEMBLE GUIDANCE REMAINS IN VERY
GOOD AGREEMENT IN THE LARGE SCALE MEAN FLOW PATTERN CONSISTING OF
A BUILDING/STRONG UPPER RIDGE OVER THE PLAINS/MS VLY WITH TROUGHS
JUST OFF THE WEST AND EAST COASTS. HOWEVER...THE PCPN PATTERN OVER
THE LOCAL AREA WILL BE MODULATED BY SHORTWV IMPULSES DIVING ESEWD
DOWN THE NERN/FRONT SIDE OF THE RIDGE WITHIN A NWLY FLOW ALOFT.
THEREFORE DESPITE ABOVE AVG CONFIDENCE IN THE MEAN PATTERN...THE
SMALLER SCALE EMBEDDED SYSTEM TIMING AND LOCAL QPF/SENSIBLE WX
IMPACT IS MORE UNCERTAIN. AS SUCH...THE FINAL DAY 3-7 GRIDS WERE
DERIVED USING A CONSENSUS BLEND IN AN EFFORT TO MITIGATE THE LOWER
CONFIDENCE IN THE SFC DETAILS AND TO BEHOLD REASONABLE CONTINUITY
THE FCST.
A MODIFIED CANADIAN HIGH PRESSURE SYSTEM WILL DOMINATE THE PATTERN
THROUGH THE WEEKEND...BRINGING RELATIVELY COOL NIGHTS WITH VALLEY
FOG AND COMFORTABLE HUMIDITY DURING THE DAY. EXPECT A MORE UNSETTLED
AND INCREASINGLY HUMID PATTERN TO EVOLVE THRU THE FIRST PART OF NEXT
WEEK..AS THE FOCUS SHIFTS TO UPPER-LEVEL DISTURBANCES CRESTING THE
PLAINS RIDGE AND DIVING ESEWD THRU THE GREAT LAKES TAKING AIM ON THE
NE STATES. MODELS SUGGEST THIS ENERGY MAY TRIGGER ONE OR MORE
ORGANIZED TSTM COMPLEXES AS THEY ROLL DOWN THE FRONT-SIDE OF THE
RIDGE.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
IFR CIGS AND VSBYS AT BFD...AND MVFR CIGS AND VSBYS AT JST AND IPT
DUE TO PATCHY FOG/MIST WILL CONTINUE THROUGH 14Z BEFORE
LIFTING/DISSIPATING BY 14Z. AFTER THAT LIFTS VFR CONDITIONS WILL
DOMINATE MOST THE DAY.
AN APPROACHING COLD FRONT FROM THE GREAT LAKES WILL MOVE THROUGH
THE REGION LATE THIS AFTERNOON THROUGH TONIGHT. THIS WILL BRING A
BETTER CHC FOR SHRA/TSRA. THIS FRONT SHOULD PASS SOUTH OF THE
REGION OVERNIGHT TONIGHT. PATCHY FOG DUE TO CLEARING SKIES AND
CALM WINDS BEHIND THE FRONT IS POSSIBLE INTO FRIDAY MORNING.
OTHERWISE IMPROVING FLYING CONDS FOR FRIDAY INTO THIS WEEKEND. WITH
VARYING TIMING...HAVE ONLY INCLUDED VCSH IN TAFS...BUT REDUCTION
IN CIG AND VSBYS WILL BE POSSIBLE.
OUTLOOK...
THU-THU NIGHT...MVFR POSSIBLE WITH SCT SHRA/TSRA.
FRI-MON...GENERALLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD/LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...FITZGERALD/LAMBERT
LONG TERM...LAMBERT/STEINBUGL
AVIATION...CERU
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
631 AM EDT THU AUG 22 2013
.SYNOPSIS...
AN UPPER LOW...CENTERED OVER THE LAUREL HIGHLANDS...WILL DRIFT
ACROSS THE SOUTHERN TIER OF PENNSYLVANIA THIS MORNING. WEAK RIDGING
IN THE WAKE OF THIS LOW WILL BE OVER THE REGION DURING THE MIDDAY
AND AFTERNOON HOURS...ACCOMPANIED BY GENERALLY FAIR WEATHER. A COLD
FRONT WILL PUSH SOUTHEAST ACROSS THE REGION LATE THURSDAY INTO EARLY
FRIDAY...FOLLOWED BY CANADIAN HIGH PRESSURE.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
REGIONAL IR SATELLITE AND RADAR LOOP AT 0815Z SHOWS EXPANDING
COVERAGE OF SHOWERS AND A FEW TSRA FROM THE LAUREL HIGHLANDS...EAST
TO THE LOWER SUSQ VALLEY. THIS CONVECTION WAS OCCURRING WITHIN A
REGION OF MDTLY STRONG UPPER DIFFLUENCE AND DIFFERENTIAL PVA JUST
AHEAD OF A SLOW-MOVING UPPER LOW. ALSO AIDING THIS CONVECTION WAS
THE VERY JUICY AIRMASS WITH LAYER PWATS IN THE 1.5-2 INCH
RANGE...ALONG WITH STRENGTHENING 850-700 MB FRONTOGENESIS.
LATEST HRRR AND RUC CONTINUES TO PAINT LIGHT TO MODERATE RAINFALL
AMOUNTS OVER THE NEXT SEVERAL HOURS ACROSS APPROXIMATELY THE
SOUTHERN 1/3 TO 1/2 OF THE CWA AS THE UPPER LOW TRACKS SLOWLY EAST
AND PROVIDES LIFT OF THE VERY MOIST AND UNSTABLE AIR. MOST OF THE
SHOWERS AND EMBEDDED TSRA WILL BE NEAR AND JUST TO THE SOUTH OF A
LINE FROM KAOO TO KSEG AND KAVP...BEFORE FOCUSING OVER THE ECENT
MTNS /SCHUYLKILL CTY AND VCNTY/ BETWEEN 10-13Z.
SFC DWPTS RANGE FROM THE U60S AND L70S IN THE SOUTH....TO THE UPPER
50S AND LOWER 60S IN THE NORTH...WHERE THE BLYR WILL LIKELY REMAIN
TOO DRY TO SUPPORT ANY CONVECTION.
EXTENSIVE CLOUD COVER AND LOW LVL MOISTURE WILL RESULT IN THE
WARMEST EARLY MORNING IN SOME TIME WITH LOWS RANGING FROM THE UPPER
50S OVR THE N MTNS...TO ARND 70F ACROSS THE LOWER SUSQ VALLEY.
THE REMNANTS OF UPPER LOW SHOULD TAKE UNTIL ARND MIDDAY TO CLEAR THE
ERN...SO WILL CARRY A CHC POPS FOR SHRA/TSRA THERE UNTIL THAT
TIME. RIDGING IN WAKE OF DEPARTING UPPER LOW SHOULD BRING A PERIOD
OF DRY CONDITIONS TO MOST OF CENTRAL PENN ON THURS BEFORE COLD FRONT
FROM THE GLAKES BRINGS ANOTHER THREAT OF CONVECTION LATE IN THE DAY
NW /AND MORE LIKELY BEGINNING THIS EVENING ACROSS THE CENTRAL MTNS/.
A RIBBON OF HIGHER PWATS BETWEEN 1.5 AND 1.75 INCHES AND SLIGHTLY
STEEPER MID-LEVEL LAPSE RATES SHOULD SUPPORT SCT SHRA/TSRA
DEVELOPING ACROSS THE NW MTNS /AHEAD OF A COLD FRONT/ DURING THE MID
TO LATE AFTN...WITH THE CONVECTION SLIDING SE THRU THE REST OF THE
REGION BETWEEN 02-06Z FRIDAY.
HIGH TEMPS THIS AFTERNOON WILL REACH THE MID AND UPPER 80S ACROSS
THE CENTRAL AND SE VALLEYS...AND AROUND 80F OVER THE HIGHER TERRAIN
OF NRN AND WRN PENN.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
AS NOTED ABOVE...THE TIMING OF THE SFC COLD FRONT AND ASSOCIATED
SHRA/TSRA WILL BE DURING THE FIRST HALF OF THE OVERNIGHT HOURS.
POPS WILL DIMINISH STEADILY AFTER MIDNIGHT AND BECOME CONFINED TO
THE SOUTHERN TIER OF THE STATE BEFORE DAYBREAK.
THE MEAN LOW-MID LEVEL FLOW VEERS AROUND TO THE NNW FRIDAY...
ALLOWING DEEP DRYING TO ADVECT INTO THE REGION DURING THE DAY. MAX
TEMPS FRIDAY WILL COOL BY A FEW TO SVRL DEG F COMPARED TO THURSDAY/S.
SFC DEWPOINTS WILL RETREAT BACK TO VERY COMFORTABLE LEVELS IN THE
UPPER 40S /NW/...AND MID 50S /SE/ FRIDAY AFTERNOON...SETTING THE
STAGE FOR A COOL LATE AUGUST NIGHT FRIDAY NIGHT.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
OVERVIEW...THE LATEST MODEL AND ENSEMBLE GUIDANCE REMAINS IN VERY
GOOD AGREEMENT IN THE LARGE SCALE MEAN FLOW PATTERN CONSISTING OF
A BUILDING/STRONG UPPER RIDGE OVER THE PLAINS/MS VLY WITH TROUGHS
JUST OFF THE WEST AND EAST COASTS. HOWEVER...THE PCPN PATTERN OVER
THE LOCAL AREA WILL BE MODULATED BY SHORTWV IMPULSES DIVING ESEWD
DOWN THE NERN/FRONT SIDE OF THE RIDGE WITHIN A NWLY FLOW ALOFT.
THEREFORE DESPITE ABOVE AVG CONFIDENCE IN THE MEAN PATTERN...THE
SMALLER SCALE EMBEDDED SYSTEM TIMING AND LOCAL QPF/SENSIBLE WX
IMPACT IS MORE UNCERTAIN. AS SUCH...THE FINAL DAY 3-7 GRIDS WERE
DERIVED USING A CONSENSUS BLEND IN AN EFFORT TO MITIGATE THE LOWER
CONFIDENCE IN THE SFC DETAILS AND TO BEHOLD REASONABLE CONTINUITY
THE FCST.
A MODIFIED CANADIAN HIGH PRESSURE SYSTEM WILL DOMINATE THE PATTERN
THROUGH THE WEEKEND...BRINGING RELATIVELY COOL NIGHTS WITH VALLEY
FOG AND COMFORTABLE HUMIDITY DURING THE DAY. EXPECT A MORE UNSETTLED
AND INCREASINGLY HUMID PATTERN TO EVOLVE THRU THE FIRST PART OF NEXT
WEEK..AS THE FOCUS SHIFTS TO UPPER-LEVEL DISTURBANCES CRESTING THE
PLAINS RIDGE AND DIVING ESEWD THRU THE GREAT LAKES TAKING AIM ON THE
NE STATES. MODELS SUGGEST THIS ENERGY MAY TRIGGER ONE OR MORE
ORGANIZED TSTM COMPLEXES AS THEY ROLL DOWN THE FRONT-SIDE OF THE
RIDGE.
&&
.AVIATION /10Z THURSDAY THROUGH MONDAY/...
SHOWERS HAVE MOVED TO THE NORTHEAST...WITH ONLY MVFR VSBYS FROM
PATCHY MIST/FOG AT BFD. ANY PATCHY FOG WILL LIFT/DISSIPATE BY 14Z.
MAINLY VFR THROUGHOUT THE DAY.
AN APPROACHING COLD FRONT FROM THE GREAT LAKES WILL MOVE THROUGH
THE REGION LATE THIS AFTERNOON THROUGH TONIGHT. THIS WILL BRING A
BETTER CHC FOR SHRA/TSRA. THIS FRONT SHOULD PASS SOUTH OF THE
REGION OVERNIGHT TONIGHT. PATCHY FOG DUE TO CLEARING SKIES AND
CALM WINDS BEHIND THE FRONT IS POSSIBLE INTO FRIDAY MORNING.
OTHERWISE IMPROVING FLYING CONDS FOR FRIDAY INTO THIS WEEKEND. WITH
VARYING TIMING...HAVE ONLY INCLUDED VCSH IN TAFS...BUT REDUCTION
IN CIG AND VSBYS WILL BE POSSIBLE.
OUTLOOK...
THU-THU NIGHT...MVFR POSSIBLE WITH SCT SHRA/TSRA.
FRI-MON...GENERALLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD/LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...FITZGERALD/LAMBERT
LONG TERM...LAMBERT/STEINBUGL
AVIATION...CERU
AREA FORECAST DISCUSSION
NWS NEW YORK NY
549 PM EDT THU AUG 22 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH THIS EVENING AND MOVE ACROSS OVERNIGHT.
HIGH PRESSURE WILL THEN BUILD IN FROM FRIDAY THROUGH SUNDAY...AND
SETTLE TO THE SOUTH ON MONDAY. A SERIES OF FRONTS WILL MOVE ACROSS
THROUGH THE MID TO LATE PORTION OF NEXT WEEK.
&&
.NEAR TERM /THROUGH FRIDAY/...
MUCH OF THE CWA HAS BEEN WORKED OVER THIS EVE. OUTSIDE OF A FEW
RESIDUAL SPRINKLES OVER THE E END OF LI...RADAR IS QUIET. THE
FRONT IS STILL ONLY ACROSS CNTRL NYSTATE.
THERE IS LIKELY SOME WEAK SUBSIDENCE IN THE WAKE OF THE SUBTLE MID
LVL SHRTWV PASSING OVER THE CWA. FOR THIS REASON...DROPPED PCPN
CHCS TIL ABOUT 00Z WHEN CONDITIONS WILL AGAIN BECOME FAVORABLE FOR
DEVELOPMENT AHEAD OF THE FRONT. EXTREME NWRN ZONES STILL HAVE OVER
2K J/KG OF SBCAPE.
CONVECTION WITH ACTUAL COLD FRONT IS FCST BY 17Z HRRR TO WEAKEN
VIA NIGHTTIME COOLING/STABILIZATION. LEFT IN SLIGHT CHANCE POP IN
SOME AREAS AFTER MIDNIGHT IN CASE ANY OF IT SHOULD SURVIVE THIS
FAR EAST. MOCLDY SKIES SHOULD CLEAR LATE AFTER FROPA...WITH LOWS
MAINLY 65-70.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH 6 PM FRIDAY/...
DRIER AIR WILL MOVE IN ON A N-NW BREEZE...WITH DEWPOINTS DROPPING
INTO THE 50S. HIGHS ON FRIDAY WILL REACH THE MID/UPPER 80S.
MOCLEAR SKIES AND DIMINISHING WINDS AS THE HIGH BUILDS OHD WILL
LEAD TO A COOLER NIGHT...WITH LOWER FRI NIGHT FROM THE MID 50S TO
MID 60S. EXCEPTION TO THIS MAY BE ACROSS LONG ISLAND...WHERE NWP
GUIDANCE HAS ADVERTISED MORE IN THE WAY OF CLOUDS AND POSSIBLE A
FEW LATE NIGHT SHOWERS AS AN UPPER LEVEL VORT MAX MOVES ACROSS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
MAIN CONTROLLING FEATURE ACROSS THE US WILL BE THE LARGE UPPER RIDGE
ACROSS THE CENTRAL US...WHICH WILL BUILD SLIGHTLY EASTWARD TOWARDS
THE EASTERN US BY THE END OF THE WEEKEND. THIS WILL PLACE THE REGION
ON THE NE EDGE OF UPPER RIDGING AND IN THE PATH OF A QUICK UPPER
FLOW FOR MUCH OF NEXT WEEK...WITH A SERIES OF WEAK DISTURBANCE
PASSING THROUGH THE NE.
AT THE SURFACE CANADIAN HIGH PRESSURE WILL BUILD INTO AND THEN SLIDE
ACROSS THE REGION THROUGH THE WEEKEND...PROVIDING FAIR AND
SEASONABLY WARM DAYTIME TEMPS. OVERNIGHT LOWS WILL LIKELY BE A BIT
CHILLY ACROSS FAR OUTLYING AREAS SAT NIGHT WITH GOOD RADIATIONAL
COOLING CONDS...PERHAPS DROPPING INTO THE UPPER 40S.
NEAR TO SLIGHTLY ABOVE SEASONABLE TEMPS AND MORE HUMID CONDITIONS
LIKELY FOR NEXT WEEK AS SURFACE HIGH PRESSURE SETTLES SOUTH OF THE
REGION AND A SERIES OF WEAK FRONTS AFFECT THE AREA. PREDICTABILITY
OF SHORTWAVES AND ASSOCIATED FRONTS IS LOW THIS FAR OUT...BUT
POTENTIAL EXISTS FOR A FEW PERIODS OF SHOWERS AND THUNDERSTORMS FROM
MONDAY AFTERNOON ONWARDS. MOST ACTIVITY WILL LIKELY BE DIURNAL AND
SCATTERED ACROSS THE INTERIOR...BUT PATTERN COULD SUPPORT AN
ORGANIZED CONVECTIVE COMPLEX AT ANY TIME DURING THE MID TO LATE WEEK
PERIOD.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
MAINLY VFR CONDITIONS OUTSIDE OF -SHRA ACTIVITY AS A COLD FRONT
APPROACHES THE AREA. MVFR POSSIBLE IN -SHRA.
ACTIVITY OVER THE AREA HAS WEAKENED AND THERE SHOULD BE A BIT OF A
BREAK BEFORE THE NEXT POTENTIAL SET OF SHRA/TSTMS AFFECTS THE
TERMINALS. WATCHING A CLUSTER OF STORMS OVER EASTERN PA AT 20Z
TRACKING ESE. STORM MOVEMENT IS SLOW AND IS CURRENTLY NOT EXPECTED
TO IMPACT THE AIRFIELD UNTIL AROUND 00Z. IT MAY WEAKEN AS IT
APPROACHES DUE TO THE LOSS OF HEATING...BUT WILL WATCH OVER THE
NEXT HOUR AND AMEND IF NEEDED. OTHERWISE...HIGH RES MODELS HAVE
BEEN INDICATING THAT THE LINE OF SHOWERS/TSTMS ASSOCIATED WITH THE
COLD FRONT BACK OVER CENTRAL NY AND PA IS EXPECTED TO WEAKEN
BEFORE REACHING THE TERMINALS. KSWF MAY SEE A SHOWER FROM IT...BUT
EVERYONE ELSE SHOULD REMAIN DRY.
FRONT WILL PUSH ACROSS THE REGION TONIGHT INTO EARLY FRI
MORNING...02Z-05Z AT KSWF TO 06Z-09Z AT KISP/KGON. THIS WILL ALLOW
WINDS TO SHIFT TO 260-280 TRUE 00Z-02Z TONIGHT...THEN TO 320-350
TRUE LATE TONIGHT INTO FRIDAY MORNING. AN ISOLATED WIND GUST UP TO
20 KT IS POSSIBLE DURING THE DAY ON FRIDAY.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHRA/TSRA
THROUGH THE EVE PUSH.
KJFK FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHRA/TSRA
THROUGH THE EVE PUSH.
KLGA FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHRA/TSRA
THROUGH THE EVE PUSH.
KTEB FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHRA/TSRA
THROUGH 02Z.
KHPN FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHRA/TSRA
THROUGH 02Z.
KISP FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHRA/TSRA
THROUGH 02Z.
OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...
.FRI-MON...VFR.
.TUE...SUB VFR POSSIBLE IN SHRA/TSRA WITH COLD FRONT.
&&
.MARINE...
TSTM THREAT HAS WANED FOR NOW...BUT WATERS INVOF NYC MAY SEE
ADDITIONAL ACTIVITY AHEAD OF AN APPROACHING COLD FRONT THIS
EVENING. OTHERWISE...POST-FRONTAL FLOW LATE TONIGHT INTO FRI COULD
GUST TO 20 KT AT TIMES ESPECIALLY NEAR SHORE...BUT SCA CONDS NOT
EXPECTED...WITH OCEAN SEAS NO HIGHER THAN 3 FT. QUIET CONDITIONS
SHOULD LAST INTO EARLY NEXT WEEK.
&&
.HYDROLOGY...
SCT SHOWERS AND THUNDERSTORMS MAINLY NORTH/WEST OF NYC THIS
EVENING COULD STILL PRODUCE LOCALIZED HEAVY RAIN AND MINOR
FLOODING.
HEAVY RAIN POTENTIAL MID TO LATE NEXT WEEK WILL BE TIED TO TSTM
ACTIVITY...WHICH HAS LOW PREDICTABILITY IN TIMING AND LOCATION AT
THIS TIME.
&&
.EQUIPMENT...
DUE TO INTERFERENCE ISSUES WITH THE U.S. COAST GUARD...THE NEW
YORK CITY NOAA ALL HAZARDS WEATHER RADIO STATION KWO35 HAS BEEN
TEMPORARILY TAKEN OUT OF SERVICE WHILE A SOLUTION IS
BEING FORMULATED.
DURING THIS TIME...THE TRANSMITTER MAY BE RETURNED TO SERVICE
INTERMITTENTLY FOR USE OF THE NOAA ALL HAZARDS RADIO PUBLIC WARNING
SYSTEM DURING POTENTIALLY DANGEROUS WEATHER SITUATIONS...FOR ROUTINE
WEEKLY TESTS OF THE WARNING SYSTEM...AND TO DETERMINE IF THE
INTERFERENCE ISSUE HAS BEEN RESOLVED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...GOODMAN/NV
NEAR TERM...JMC/GOODMAN
SHORT TERM...GOODMAN
LONG TERM...NV
AVIATION...JP
MARINE...GOODMAN/NV
HYDROLOGY...GOODMAN/NV
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
509 PM EDT THU AUG 22 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH THIS EVENING AND MOVE ACROSS OVERNIGHT.
HIGH PRESSURE WILL THEN BUILD IN FROM FRIDAY THROUGH SUNDAY...AND
SETTLE TO THE SOUTH ON MONDAY. A SERIES OF FRONTS WILL MOVE ACROSS
THROUGH THE MID TO LATE PORTION OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MID LEVEL TROUGH OVER THE MID ATLC REGION STILL SPARKING SHOWERS
AND ISOLD TSTMS. STRONGEST ACTIVITY HAS ORGANIZED WELL TO THE
SOUTH...SO AREA OF MAINLY LIGHT PRECIP SHOULD CONTINUE E FROM NYC
METRO INTO LONG ISLAND AND COASTAL CT INTO EARLY THIS EVENING.
WATCHING ENHANCED CU FIELD EXTENDING FROM THE CATSKILLS TO THE
POCONOS FOR ADDITIONAL SCT DEVELOPMENT THAT COULD IMPACT AREAS
MAINLY NORTH/WEST OF NYC INTO THIS EVENING. MLCAPE INCREASING TO
1000-1500 J/KG NORTH/WEST OF NYC BUT SHEAR IS WEAK...SO MAIN MODE
WILL BE PULSE CELLS...THE STRONGER IF WHICH ARE CAPABLE OF HEAVY
RAIN AND GUSTY WINDS.
CONVECTION WITH ACTUAL COLD FRONT STILL OVER WRN PA/NY IS FCST BY
17Z HRRR TO WEAKEN VIA NIGHTTIME COOLING/STABILIZATION. LEFT IN
SLIGHT CHANCE POP IN SOME AREAS AFTER MIDNIGHT IN CASE ANY OF IT
SHOULD SURVIVE THIS FAR EAST. MOCLDY SKIES SHOULD CLEAR LATE
AFTER FROPA...WITH LOWS MAINLY 65-70.
A MODERATE RIP CURRENT RISK CONTINUES FROM SMITH POINT BEACH EAST
TO MONTAUK INTO THIS EVENING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
DRIER AIR WILL MOVE IN ON A N-NW BREEZE...WITH DEWPOINTS DROPPING
INTO THE 50S. HIGHS ON FRIDAY WILL REACH THE MID/UPPER 80S.
MOCLEAR SKIES AND DIMINISHING WINDS AS THE HIGH BUILDS OHD WILL
LEAD TO A COOLER NIGHT...WITH LOWER FRI NIGHT FROM THE MID 50S TO
MID 60S. EXCEPTION TO THIS MAY BE ACROSS LONG ISLAND...WHERE NWP
GUIDANCE HAS ADVERTISED MORE IN THE WAY OF CLOUDS AND POSSIBLE A
FEW LATE NIGHT SHOWERS AS AN UPPER LEVEL VORT MAX MOVES ACROSS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
MAIN CONTROLLING FEATURE ACROSS THE US WILL BE THE LARGE UPPER RIDGE
ACROSS THE CENTRAL US...WHICH WILL BUILD SLIGHTLY EASTWARD TOWARDS
THE EASTERN US BY THE END OF THE WEEKEND. THIS WILL PLACE THE REGION
ON THE NE EDGE OF UPPER RIDGING AND IN THE PATH OF A QUICK UPPER
FLOW FOR MUCH OF NEXT WEEK...WITH A SERIES OF WEAK DISTURBANCE
PASSING THROUGH THE NE.
AT THE SURFACE CANADIAN HIGH PRESSURE WILL BUILD INTO AND THEN SLIDE
ACROSS THE REGION THROUGH THE WEEKEND...PROVIDING FAIR AND
SEASONABLY WARM DAYTIME TEMPS. OVERNIGHT LOWS WILL LIKELY BE A BIT
CHILLY ACROSS FAR OUTLYING AREAS SAT NIGHT WITH GOOD RADIATIONAL
COOLING CONDS...PERHAPS DROPPING INTO THE UPPER 40S.
NEAR TO SLIGHTLY ABOVE SEASONABLE TEMPS AND MORE HUMID CONDITIONS
LIKELY FOR NEXT WEEK AS SURFACE HIGH PRESSURE SETTLES SOUTH OF THE
REGION AND A SERIES OF WEAK FRONTS AFFECT THE AREA. PREDICTABILITY
OF SHORTWAVES AND ASSOCIATED FRONTS IS LOW THIS FAR OUT...BUT
POTENTIAL EXISTS FOR A FEW PERIODS OF SHOWERS AND THUNDERSTORMS FROM
MONDAY AFTERNOON ONWARDS. MOST ACTIVITY WILL LIKELY BE DIURNAL AND
SCATTERED ACROSS THE INTERIOR...BUT PATTERN COULD SUPPORT AN
ORGANIZED CONVECTIVE COMPLEX AT ANY TIME DURING THE MID TO LATE WEEK
PERIOD.
&&
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
MAINLY VFR CONDITIONS OUTSIDE OF -SHRA ACTIVITY AS A COLD FRONT
APPROACHES THE AREA. MVFR POSSIBLE IN -SHRA.
ACTIVITY OVER THE AREA HAS WEAKENED AND THERE SHOULD BE A BIT OF A
BREAK BEFORE THE NEXT POTENTIAL SET OF SHRA/TSTMS AFFECTS THE
TERMINALS. WATCHING A CLUSTER OF STORMS OVER EASTERN PA AT 20Z
TRACKING ESE. STORM MOVEMENT IS SLOW AND IS CURRENTLY NOT EXPECTED
TO IMPACT THE AIRFIELD UNTIL AROUND 00Z. IT MAY WEAKEN AS IT
APPROACHES DUE TO THE LOSS OF HEATING...BUT WILL WATCH OVER THE
NEXT HOUR AND AMEND IF NEEDED. OTHERWISE...HIGH RES MODELS HAVE
BEEN INDICATING THAT THE LINE OF SHOWERS/TSTMS ASSOCIATED WITH THE
COLD FRONT BACK OVER CENTRAL NY AND PA IS EXPECTED TO WEAKEN
BEFORE REACHING THE TERMINALS. KSWF MAY SEE A SHOWER FROM IT...BUT
EVERYONE ELSE SHOULD REMAIN DRY.
FRONT WILL PUSH ACROSS THE REGION TONIGHT INTO EARLY FRI
MORNING...02Z-05Z AT KSWF TO 06Z-09Z AT KISP/KGON. THIS WILL ALLOW
WINDS TO SHIFT TO 260-280 TRUE 00Z-02Z TONIGHT...THEN TO 320-350
TRUE LATE TONIGHT INTO FRIDAY MORNING. AN ISOLATED WIND GUST UP TO
20 KT IS POSSIBLE DURING THE DAY ON FRIDAY.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHRA/TSRA
THROUGH THE EVE PUSH.
KJFK FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHRA/TSRA
THROUGH THE EVE PUSH.
KLGA FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHRA/TSRA
THROUGH THE EVE PUSH.
KTEB FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHRA/TSRA
THROUGH 02Z.
KHPN FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHRA/TSRA
THROUGH 02Z.
KISP FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHRA/TSRA
THROUGH 02Z.
OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...
.FRI-MON...VFR.
.TUE...SUB VFR POSSIBLE IN SHRA/TSRA WITH COLD FRONT.
&&
.MARINE...
TSTM THREAT HAS WANED FOR NOW...BUT WATERS INVOF NYC MAY SEE
ADDITIONAL ACTIVITY AHEAD OF AN APPROACHING COLD FRONT THIS
EVENING. OTHERWISE...POST-FRONTAL FLOW LATE TONIGHT INTO FRI COULD
GUST TO 20 KT AT TIMES ESPECIALLY NEAR SHORE...BUT SCA CONDS NOT
EXPECTED...WITH OCEAN SEAS NO HIGHER THAN 3 FT. QUIET CONDITIONS
SHOULD LAST INTO EARLY NEXT WEEK.
&&
.HYDROLOGY...
SCT SHOWERS AND THUNDERSTORMS MAINLY NORTH/WEST OF NYC THIS
EVENING COULD STILL PRODUCE LOCALIZED HEAVY RAIN AND MINOR
FLOODING.
HEAVY RAIN POTENTIAL MID TO LATE NEXT WEEK WILL BE TIED TO TSTM
ACTIVITY...WHICH HAS LOW PREDICTABILITY IN TIMING AND LOCATION AT
THIS TIME.
&&
.EQUIPMENT...
DUE TO INTERFERENCE ISSUES WITH THE U.S. COAST GUARD...THE NEW
YORK CITY NOAA ALL HAZARDS WEATHER RADIO STATION KWO35 HAS BEEN
TEMPORARILY TAKEN OUT OF SERVICE WHILE A SOLUTION IS
BEING FORMULATED.
DURING THIS TIME...THE TRANSMITTER MAY BE RETURNED TO SERVICE
INTERMITTENTLY FOR USE OF THE NOAA ALL HAZARDS RADIO PUBLIC WARNING
SYSTEM DURING POTENTIALLY DANGEROUS WEATHER SITUATIONS...FOR ROUTINE
WEEKLY TESTS OF THE WARNING SYSTEM...AND TO DETERMINE IF THE
INTERFERENCE ISSUE HAS BEEN RESOLVED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...GOODMAN/NV
NEAR TERM...GOODMAN
SHORT TERM...GOODMAN
LONG TERM...NV
AVIATION...JP
MARINE...GOODMAN/NV
HYDROLOGY...GOODMAN/NV
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
356 PM EDT THU AUG 22 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH THIS EVENING AND MOVE ACROSS OVERNIGHT.
HIGH PRESSURE WILL THEN BUILD IN FROM FRIDAY THROUGH SUNDAY...AND
SETTLE TO THE SOUTH ON MONDAY. A SERIES OF FRONTS WILL MOVE ACROSS
THROUGH THE MID TO LATE PORTION OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
MID LEVEL TROUGH OVER THE MID ATLC REGION STILL SPARKING SHOWERS
AND ISOLD TSTMS. STRONGEST ACTIVITY HAS ORGANIZED WELL TO THE
SOUTH...SO AREA OF MAINLY LIGHT PRECIP SHOULD CONTINUE E FROM NYC
METRO INTO LONG ISLAND AND COASTAL CT INTO EARLY THIS EVENING.
WATCHING ENHANCED CU FIELD EXTENDING FROM THE CATSKILLS TO THE
POCONOS FOR ADDITIONAL SCT DEVELOPMENT THAT COULD IMPACT AREAS
MAINLY NORTH/WEST OF NYC INTO THIS EVENING. MLCAPE INCREASING TO
1000-1500 J/KG NORTH/WEST OF NYC BUT SHEAR IS WEAK...SO MAIN MODE
WILL BE PULSE CELLS...THE STRONGER IF WHICH ARE CAPABLE OF HEAVY
RAIN AND GUSTY WINDS.
CONVECTION WITH ACTUAL COLD FRONT STILL OVER WRN PA/NY IS FCST BY
17Z HRRR TO WEAKEN VIA NIGHTTIME COOLING/STABILIZATION. LEFT IN
SLIGHT CHANCE POP IN SOME AREAS AFTER MIDNIGHT IN CASE ANY OF IT
SHOULD SURVIVE THIS FAR EAST. MOCLDY SKIES SHOULD CLEAR LATE
AFTER FROPA...WITH LOWS MAINLY 65-70.
A MODERATE RIP CURRENT RISK CONTINUES FROM SMITH POINT BEACH EAST
TO MONTAUK INTO THIS EVENING.
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
DRIER AIR WILL MOVE IN ON A N-NW BREEZE...WITH DEWPOINTS DROPPING
INTO THE 50S. HIGHS ON FRIDAY WILL REACH THE MID/UPPER 80S.
MOCLEAR SKIES AND DIMINISHING WINDS AS THE HIGH BUILDS OHD WILL
LEAD TO A COOLER NIGHT...WITH LOWER FRI NIGHT FROM THE MID 50S TO
MID 60S. EXCEPTION TO THIS MAY BE ACROSS LONG ISLAND...WHERE NWP
GUIDANCE HAS ADVERTISED MORE IN THE WAY OF CLOUDS AND POSSIBLE A
FEW LATE NIGHT SHOWERS AS AN UPPER LEVEL VORT MAX MOVES ACROSS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
MAIN CONTROLLING FEATURE ACROSS THE US WILL BE THE LARGE UPPER RIDGE
ACROSS THE CENTRAL US...WHICH WILL BUILD SLIGHTLY EASTWARD TOWARDS
THE EASTERN US BY THE END OF THE WEEKEND. THIS WILL PLACE THE REGION
ON THE NE EDGE OF UPPER RIDGING AND IN THE PATH OF A QUICK UPPER
FLOW FOR MUCH OF NEXT WEEK...WITH A SERIES OF WEAK DISTURBANCE
PASSING THROUGH THE NE.
AT THE SURFACE CANADIAN HIGH PRESSURE WILL BUILD INTO AND THEN SLIDE
ACROSS THE REGION THROUGH THE WEEKEND...PROVIDING FAIR AND
SEASONABLY WARM DAYTIME TEMPS. OVERNIGHT LOWS WILL LIKELY BE A BIT
CHILLY ACROSS FAR OUTLYING AREAS SAT NIGHT WITH GOOD RADIATIONAL
COOLING CONDS...PERHAPS DROPPING INTO THE UPPER 40S.
NEAR TO SLIGHTLY ABOVE SEASONABLE TEMPS AND MORE HUMID CONDITIONS
LIKELY FOR NEXT WEEK AS SURFACE HIGH PRESSURE SETTLES SOUTH OF THE
REGION AND A SERIES OF WEAK FRONTS AFFECT THE AREA. PREDICTABILITY
OF SHORTWAVES AND ASSOCIATED FRONTS IS LOW THIS FAR OUT...BUT
POTENTIAL EXISTS FOR A FEW PERIODS OF SHOWERS AND THUNDERSTORMS FROM
MONDAY AFTERNOON ONWARDS. MOST ACTIVITY WILL LIKELY BE DIURNAL AND
SCATTERED ACROSS THE INTERIOR...BUT PATTERN COULD SUPPORT AN
ORGANIZED CONVECTIVE COMPLEX AT ANY TIME DURING THE MID TO LATE WEEK
PERIOD.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
AREA OF SHRA/TSRA OVER CENTRAL NJ SHOULD PASS SOUTH OF MOST OF THE
CITY TERMINALS. KJFK COULD GET CLIPPED BY THESE STORMS...SO PUT IN
A TEMPO GROUP FOR -TSRA. OTHERWISE...-SHRA ACTIVITY OUT AHEAD OF
AN APPROACHING COLD FRONT. CONDITIONS FOR THE MOST PART SHOULD BE
VFR...BUT COULD LOWER TO MVFR OR LOWER IN HEAVIER SHRA/TSRA ACTIVITY.
FRONT WILL PUSH ACROSS THE REGION TONIGHT INTO EARLY FRI MORNING
02Z-05Z AT KSWF TO 06Z-09Z AT KISP/KGON.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KJFK FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
KLGA FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
KTEB FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
KHPN FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
KISP FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
.THU NIGHT...PSBL MVFR TO LOCALLY IFR WITH ANY RESIDUAL
SHOWERS/TSTMS. COLD FROPA.
.FRI-MON...VFR.
&&
.MARINE...
TSTM THREAT HAS WANED FOR NOW...BUT WATERS INVOF NYC MAY SEE
ADDITIONAL ACTIVITY AHEAD OF AN APPROACHING COLD FRONT THIS
EVENING. OTHERWISE...POST-FRONTAL FLOW LATE TONIGHT INTO FRI COULD
GUST TO 20 KT AT TIMES ESPECIALLY NEAR SHORE...BUT SCA CONDS NOT
EXPECTED...WITH OCEAN SEAS NO HIGHER THAN 3 FT. QUIET CONDITIONS
SHOULD LAST INTO EARLY NEXT WEEK.
&&
.HYDROLOGY...
SCT SHOWERS AND THUNDERSTORMS MAINLY NORTH/WEST OF NYC THIS
EVENING COULD STILL PRODUCE LOCALIZED HEAVY RAIN AND MINOR
FLOODING.
HEAVY RAIN POTENTIAL MID TO LATE NEXT WEEK WILL BE TIED TO TSTM
ACTIVITY...WHICH HAS LOW PREDICTABILITY IN TIMING AND LOCATION AT
THIS TIME.
&&
.EQUIPMENT...
DUE TO INTERFERENCE ISSUES WITH THE U.S. COAST GUARD...THE NEW
YORK CITY NOAA ALL HAZARDS WEATHER RADIO STATION KWO35 HAS BEEN
TEMPORARILY TAKEN OUT OF SERVICE WHILE A SOLUTION IS
BEING FORMULATED.
DURING THIS TIME...THE TRANSMITTER MAY BE RETURNED TO SERVICE
INTERMITTENTLY FOR USE OF THE NOAA ALL HAZARDS RADIO PUBLIC WARNING
SYSTEM DURING POTENTIALLY DANGEROUS WEATHER SITUATIONS...FOR ROUTINE
WEEKLY TESTS OF THE WARNING SYSTEM...AND TO DETERMINE IF THE
INTERFERENCE ISSUE HAS BEEN RESOLVED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...GOODMAN/NV
NEAR TERM...GOODMAN
SHORT TERM...GOODMAN
LONG TERM...NV
AVIATION...JP
MARINE...GOODMAN/NV
HYDROLOGY...GOODMAN/NV
EQUIPMENT...GOODMAN
AREA FORECAST DISCUSSION
NWS NEW YORK NY
153 PM EDT THU AUG 22 2013
.SYNOPSIS...
A COLD FRONT APPROACHES FROM THE NORTHWEST THIS AFTERNOON...THEN MOVES
ACROSS THE REGION TONIGHT. HIGH PRESSURE BUILDS INTO THE TRI-
STATE BEHIND THE FRONT...THEN SETTLES TO THE SOUTH LATE THIS WEEKEND. A
SERIES OF TROUGHS WILL TRACK ACROSS THE REGION THROUGH THE MIDDLE
PORTION OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
PASSING 700-500 HPA SHORTWAVE COUPLED WITH PRE-FRONTAL SHRA
RESPONSIBLE FOR ONGOING SHRA/TSTM ACROSS THE TRI-STATE. HAVE
INCREASED POPS TO CATEGORICAL OVER NEXT FEW HOURS OVER MAINLY LONG
ISLAND BASED ON LATEST RADAR TRENDS.
STILL HAVE ANOTHER SHORTWAVE TO COME...SO HAVE CONTINUED WITH SCT
SHRA/TSTMS FOR THIS AFTERNOON. CAPES ON 12Z SOUNDINGS RANGED FROM
1000-2000 J/KG...BUT WITH FREEZING LEVELS OVER 14000 FT AND -20C
LEVEL AROUND 25000 FT IT IS A VERY WARM PROFILE - SO LOCALLY HEAVY
RAIN IS MAIN THREAT. SEE HYDROLOGY SECTION FOR DETAILS. GIVEN CAPE
CANNOT COMPLETELY RULE OUT LOCALLY STRONG TO SEVERE STORM -
ESPECIALLY OVER WESTERN ZONES IF THERE IS SOME SUN THIS AFTERNOON.
LATEST SATELLITE TRENDS MAKE IDEA OF EXTENSIVE BREAKS IN THE SUN
DOUBTFUL...AND BASED ON HOURLY TEMPERATURES CURRENTLY RUNNING
QUITE A BIT COOLER THAN FORECAST HAVE LOWERED HIGHS A FEW DEGREES
- CONSISTENT WITH A BLEND OF HRRR AND NAM 2-METER TEMPERATURES
WITH 12Z MET/6Z MAV AND LAV GUIDANCE.
THERE IS A MODERATE RISK OF RIP CURRENTS FROM SMITHS POINT BEACH
EAST TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
COLD FRONT MOVES ACROSS THE REGION FROM WEST TO EAST THROUGH
MIDNIGHT TONIGHT...AND THEN H5 TROUGH MOVES ACROSS THE REGION ON
FRIDAY. SHOWERS/TSTMS TAPER OFF FROM WEST TO EAST BY FRIDAY
MORNING...AND THEN DRYER AIR FILTERS INTO THE REGION AS HIGH PRES
BEGINS TO BUILD EAST AND SFC DEW POINTS DROP INTO THE MID/UPPER
50S.
LOWS TONIGHT WILL GENERALLY DROP INTO THE LOWER 70S IN/AROUND
NYC...AND INTO THE 60S ELSEWHERE. HIGHS ON FRIDAY WILL REACH THE
MID/UPPER 80S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
THIS TIME FRAME WILL FEATURE EXITING TROUGH OVER THE
NORTHEAST...WITH LARGE RIDGE BUILDING IN ACROSS THE MIDDLE OF THE
COUNTRY. BY EARLY NEXT WEEK...HEIGHTS LOWER ACROSS THE
NORTHEAST...WITH SUBTLE MODEL DIFFERENCES NOTED IN THE MEDIUM TO
LONG RANGE WITH REGARD TO EMBEDDED SHORTWAVES AND ASSOCIATED SFC
TROUGHS.
WILL THUS NOT STRAY TOO FAR FROM FORECAST...AND A DRY WEEKEND WILL
GIVE WAY TO UNSETTLED WEATHER EARLY TO MID WEEK NEXT WEEK. TIMING
OF ANY SCATTERED CONVECTION WILL BE EXTREMELY DIFFICULT TO DO THIS
FAR OUT.
OVERALL...NEAR NORMAL TEMPERATURES ARE ANTICIPATED THROUGH THIS
TIME FRAME FOR OUR LOCAL AREA...WITH THE HEAT REMAINING ACROSS THE
MIDDLE PORTION OF THE COUNTRY UNDERNEATH THE RIDGE.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AREA OF SHRA/TSRA OVER CENTRAL NJ SHOULD PASS SOUTH OF MOST OF THE
CITY TERMINALS. KFJK COULD GET CLIPPED BY THESE STORMS...SO PUT IN
A TEMPO GROUP FOR -TSRA. OTHERWISE...-SHRA ACTIVITY OUT AHEAD OF
AN APPROACHING COLD FRONT. CONDITIONS FOR THE MOST PART SHOULD BE
VFR...BUT COULD LOWER TO MVFR OR LOWER IN HEAVIER SHRA/TSRA ACTIVITY.
FRONT WILL PUSH ACROSS THE REGION TONIGHT INTO EARLY FRI MORNING
...02Z-05Z AT KSWF TO 06Z-09Z AT KISP/KGON.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KJFK FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
KLGA FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
KTEB FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
KHPN FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
KISP FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TIMING OF SHOWERS AND
ANY TSRA DEVELOPMENT TODAY.
OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
.THU NIGHT...PSBL MVFR TO LOCALLY IFR WITH ANY RESIDUAL
SHOWERS/TSTMS. COLD FROPA.
.FRI-MON...VFR.
&&
.MARINE...
THUNDERSTORMS LIKELY ACROSS LONG ISLAND SOUND AND POSSIBLE ACROSS
THE REMAINDER OF THE WATERS THROUGH THIS EVENING.
AN APPROACHING COLD FRONT THIS AFTERNOON....THAT CROSSES THE WATERS
TONIGHT COULD BRING SUSTAINED WINDS UP TO 15 KT GUSTS UP TO 20 KT
ON THE COASTAL OCEAN WATERS THROUGH TONIGHT. OTHERWISE...WINDS ARE
EXPECTED TO REMAIN 10 KT OR LESS OVER AREA WATERS THROUGH FRIDAY.
WITH THESE RELATIVELY LIGHT WINDS...SEAS ON THE COASTAL OCEAN
WATERS SHOULD REMAIN AT 3 FT OR LESS AND ON THE REMAINDER OF THE
WATERS 1 FT OR LESS THROUGH FRIDAY NIGHT AS WELL.
SUB SCA CONDITIONS ANTICIPATED FROM FRIDAY NIGHT INTO EARLY NEXT
WEEK.
&&
.HYDROLOGY...
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY THROUGH
TONIGHT. WITH PRECIPITABLE WATER VALUES OF 1 1/2 TO 2
INCHES...ANY THUNDERSTORMS THAT DO DEVELOP COULD PRODUCE LOCALLY
HEAVY RAIN...AND POSSIBLY MINOR FLOODING OF URBAN AND/OR POOR
DRAINAGE AREAS AS A RESULT. ISOLATED FLASH FLOODING...WHILE HIGHLY
UNLIKELY CANNOT BE COMPLETELY RULED OUT IF TRAINING OCCURS.
MAINLY DRY CONDITIONS ARE EXPECTED OVER THE WEEKEND. LOCAL HEAVY
RAIN WILL BE POSSIBLE WITH ANY SHOWERS AND THUNDERSTORMS NEXT
WEEK.
&&
.EQUIPMENT...
THE NOAA ALL HAZARDS WEATHER RADIO TRANSMITTER IN NEW YORK CITY
HAS BEEN REMOVED FROM SERVICE. TECHNICIANS CONTINUE TO WORK ON THE
SITUATION AND A TIME OF RETURN TO SERVICE IS UNKNOWN.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MPS/PW
NEAR TERM...MPS/PW
SHORT TERM...MPS
LONG TERM...PW
AVIATION...JP
MARINE...MPS/PW
HYDROLOGY...MPS/PW
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
ISSUED BY NATIONAL WEATHER SERVICE LINCOLN IL
310 PM CDT THU AUG 22 2013
.DISCUSSION...
934 AM...MORNING UPDATE...INCREASED POPS FOR THE ENTIRE AREA
THROUGH EARLY/MID AFTERNOON. LARGE AREA OF SHOWERS WITH EMBEDDED
TSRA CONTINUES TO SLOWLY SAG SOUTH ACROSS THE SOUTHERN CWA.
CONVECTION OVER/ENTERING LASALLE COUNTY WILL HAVE THE HEAVIEST
RAINFALL RATES THAT MAY REACH 1 TO 2 INCHES PER HOUR IN SOME
LOCATIONS. OFF TO THE NORTHWEST...A LINE OF TSRA CONTINUES TO MOVE
EAST ACROSS SOUTHERN WI AND NORTHERN IL. WINDS GUSTED TO 43 KTS AT
KEFT JUST BEFORE THE TOP OF THE HOUR. WHILE STRONG WIND GUSTS WILL
REMAIN POSSIBLE ACROSS FAR NORTHERN IL...NOT ANTICIPATING ANY
WIDESPREAD SEVERE POTENTIAL. THIS COMPLEX IS ASSOCIATED WITH A
SHORTWAVE WHICH EVENTUALLY SLIDES SOUTHEAST ACROSS THE AREA LATE
THIS MORNING INTO EARLY THIS AFTERNOON...THUS EXPECT SHRA/TSRA TO
CONTINUE THROUGH EARLY/MID AFTERNOON AS IT SLIDES SOUTHEAST. HIGH
TEMPERATURES WILL LIKELY BE LOWER THAN CURRENTLY ADVERTISED AND
WILL NEED TO ADJUST THOSE SOON...THOUGH WITH SOME SUNSHINE BY LATE
AFTERNOON...ESPECIALLY ACROSS NORTHERN IL...COULD SEE SOME
RECOVERY BACK INTO THE LOWER 80S. CMS
//PREV DISCUSSION...
329 AM CDT
THE PRIMARY FORECAST CHALLENGES ARE CHANCES FOR STORMS TODAY AND
EARLY THIS EVE FOLLOWED BY THE HEAT...POTENTIALLY
PROLONGED...DURING NEXT WEEK.
THIS MORNING...A SOMEWHAT TRUBULENET...DISORGANIZED...AND EVEN
OVERTURNED ATMOSPHERE IS IN PLACE WITH ONE MCS HAVING GONE
THROUGH LATE LAST NIGHT ACROSS LAKE MI...WITH OUTFLOW STILL
PROGRESSING SOUTHEAST ACROSS THE CWA AS OF 315 AM. THIS IS
TRIGGERING A FEW STORMS THOUGH NOTHING ROBUST. FURTHER WEST AN MCS
EVOLVING EASTWARD ACROSS NORTHERN IA ALONG THE FRONTAL
BOUNDARY...WHICH IS VERY DIFFUSE EARLY TODAY...LOOKS TO WORK
EASTWARD WITHIN THE INSTABILITY MAXIMUM THROUGH THE MORNING. IN
ADVANCE OF THIS...NEAR THE BOUNDARY...THERE HAVE BEEN SOME
ISOLATED STORMS WITHIN THE HIGH PWAT AIR AND GENTLE WARM AIR
ADVECTION BUMPING UP AGAINST THE FRONT. SO ALL OF THIS LIKELY WILL
RESULT IN CONTINUED ISOLATED TO SCATTERED STORM GENERATION THIS
MORNING.
THIS AFTERNOON AND EVENING...WHILE THE IA MCS IS LIKELY TO BEGIN
DECAYING SOME LATER THIS MORNING GIVEN LIMITED DEEP LAYER
SHEAR...REMNANTS OF WHAT IS LEFT ALONG WITH A FORECAST
CONVECTIVELY ENHANCED WAVE BY THE RAP WILL MOVE INTO THE WESTERN
CWA LATE THIS MORNING/EARLY THIS AFTERNOON. THE POTENTIAL FOR THIS
TO RE-INSTIGATE STORMS IS CERTAINLY THERE WITH THE UNSTABLE AIR
MASS STILL IN PLACE AND NOT EXPECTED TO VACATE UNTIL THIS EVE DUE
TO THE SLOW COOL FRONTAL APPROACH FROM THE NORTH. MLCAPE VALUES
OF 1500-3000 J/KG ARE FORECAST BY THE NAM TO BUILD ACROSS THE
WESTERN AND SOUTHERN CWA...BASICALLY IN THOSE AREAS AWAY FROM THE
STABILIZING ONSHORE COMPONENT OFF THE LAKE. GIVEN LITTLE
INHIBITION THE TRIGGER OF THIS IMPULSE/MCV COULD BE ENOUGH TO
SPARK STORMS AND THE SUITE OF CONVECTIVE ALLOWING GUIDANCE HAS
MEMBERS THAT DO JUST THAT. SO HAVE INCREASED POPS SOME INCLUDING
HOLDING ONTO THEM LONGER. COULD CONCEIVABLY SEE SOME STORMS LINGER
INTO THE EVE...NAMELY SOUTH OF I-80. WITH LIMITED UPPER FORCING
AND DYNAMICS THE POTENTIAL FOR ORGANIZATION TOWARD ROBUST STORMS
REMAINS PRIMARILY LOW...THOUGH A FEW ISOLATED NEAR TO SEVERE
STORMS MAY DEVELOP. TEMPERATURES TODAY LOOK TO PEAK IN THE MID 80S
IN THOSE AREAS AWAY FROM THE LAKE WHERE AN ONSHORE COMPONENT WILL
INCREASE THIS AFTERNOON. HIGHS LAKESIDE LOOK TO BE IN THE UPPER
70S.
QUIET WEATHER IS EXPECTED FRI AND SAT WITH HIGHS AROUND NORMAL.
DEW POINTS IN THE 40S STILL LOOK PLAUSIBLE FRI AFTERNOON FOR
SEVERAL AREAS. FRI NIGHT LOOKS CLEAR AND CALM WITH HIGH
CONFIDENCE SO CONTINUE TO ADVERTISE LOWER TO MID 50S IN MOST
OUTLYING AREAS.
NEXT WEEK IS THE FINAL WEEK OF METEOROLOGICAL SUMMER AND IT IS
SHAPING UP TO BE EVERY BIT SUMMER...AT LEAST THE FIRST HALF OF
IT BUT POSSIBLY MUCH OF IT. WITH THE CURRENT TROUGH OVER CANADA
ONLY GIVING A GLANCING BLOW...THE RIDGE BUILDS BACK NORTHWARD
ACROSS THE CENTRAL TO EASTERN PARTS OF THE COUNTRY BY LATE IN THE
WEEKEND. DPROG/DTS FROM BOTH THE EC AND GFS HAVE INDICATED A
FURTHER NORTH 500MB RIDGE CENTER IN THE PAST 24 HOURS...AND THIS
HAS RESULTED IN A WARMING GUIDANCE TREND. THE 594DM RIDGE
PLACEMENT JUST TO THE WEST...MODEST AND WARM SW/WSW 850-925MB
FLOW...AND A DRY COLUMN IS A PATTERN CONDUCIVE FOR WIDESPREAD
LOWER-MID 90S MON AND TUE WITH THE 90 THRESHOLD LIKELY REACHED IN
PLACES ON SUN. THE JET IS ADVERTISED TO BE ACTIVE ON THE NORTH SIDE
OF THIS WITH BROAD LOW PRESSURE ACROSS THE HIGH PLAINS LIKELY
RESULTING IN MULTIPLE MCS DEVELOPMENT IF THIS PATTERN IS CORRECT.
AT THIS TIME...THESE ARE EXPECTED TO REMAIN NORTH BUT DEPENDING ON
FREQUENCY OF THEM LIKELY WILL DICTATE HOW FAR AND QUICKLY SOUTH
THE SURFACE BOUNDARY ADVANCES. WITH NO REAL DEW POINT SCOURING TO
OUR SOUTH FROM OUR CURRENT BOUNDARY...THESE SHOULD REBOUND TO AT
LEAST THE UPPER 60S BY MON AND HOLD TO SLIGHTLY INCREASE AS LONG
AS THE HEAT PERSISTS. BY TUE THIS RESULTS IN FORECAST HEAT INDICES
AT 100 TO 105 IN SOME PLACES /NOT CHICAGO AT THIS TIME/. WHILE
THIS PERIOD IS STILL NUMEROUS DAYS OUT...THERE SEEM TO BE A
LIMITED SET OF FACTORS PRIOR TO WED THAT COULD REALLY BOTCH UP THE
HEAT GIVEN THE AMPLITUDE OF THE RIDGE. WILL CONTINUE TO HIGHLIGHT
IN THE HWO.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* TIMING OF ENDING OF LIGHT RAIN SHOWERS...AND TIMING WIND SHIFT
LATE THIS AFTERNOON AND EARLY EVENING.
07
//DISCUSSION...UPDATED 18Z...
MCS WITH WIDESPREAD SHOWERS OVER NORTHEAST IL TO CONTINUE TO WEAKEN
AS IT DRIFTS ESE AND DEPARTS NE IL DURING NEXT FEW HOURS THROUGH MID
AFTERNOON. THUNDERSTORMS SHOULD STAY SOUTH OF I-80 AND OVER SOUTHERN
LAKE MICHIGAN...BUT MODERATE RAIN SHOWERS STILL LIKELY UNTIL 20Z AT
ORD AND MDW WITH MVFR VSBYS AND CEILINGS POSSIBLE.
A COLD FRONT WHICH CURRENTLY STRETCHES FROM GRAND RAPIDS MI WSW TO
JUST NORTH OF CHICAGO TO WATERLOO IA WILL SAG SLOWLY SOUTHWARD
ACROSS THE CHICAGO METRO NEXT 1-3 HOURS THROUGH MID AFTERNOON.
TIMING THE WIND SHIFT WILL BE SOMEWHAT CHALLENGING WITH CURRENT
PROJECTIONS HAVING WEST WINDS 10-15 KTS AND GUSTS 13-18 KTS TO
SHIFT NNW BY 20Z AND NE AFTER 22Z AND DIMINISH TO 5-9 KTS LATE THIS
AFTERNOON AND EARLY EVENING. VFR CIGS OF 3-5K FT POSSIBLE BEHIND
THE FRONT DURING THIS AFTERNOON AND THEN SCATTERED OUT LATER THIS
AFTERNOON WITH BROKEN-OVC MID/HIGH CLOUDS LINGERING INTO THIS
EVENING. MVFR VSBYS WITH LIGHT FOG SHOULD STAY MORE INLAND TOWARD
RFD WHERE ENE WINDS BECOMING LIGHTER BETWEEN 08Z-14Z AND KEPT VFR
VSBYS AT ORD AND MDW. SCATTERED CLOUDS OVERNIGHT INTO FRIDAY WITH
ENE WINDS OF 7-10 KTS.
07
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONIDENCE IN TIMING. SCATTERED LIGHT SHOWERS TO GRADUALLY
DIMINISH FROM THE NW DURING MID AND LATE AFTERNOON AS MCS
WEAKENS AND TRACKS ESE OUT OF NE IL INTO NORTHERN INDIANA AND SOUTHERN
LOWER MI. VFR CEILINGS AND VISIBILITIES EXPECTED TO PREVAIL THROUGH
FRIDAY.
* MEDIUM CONFIDENCE IN WIND...WEST WINDS OF 4 TO 9 KTS HAVING RECENTLY
SHIFTED SSE ON BACK SIDE OF 1020 MB MESO-HIGH PRESSURE FROM WEAKENING
MCS JUST SE OF CHICAGO. WINDS TO SHIFT NE IN THE NEXT FEW HOURS AS
COLD FRONT NEAR THE WI/IL BORDER DROPS SOUTHWARD ACROSS THE CHICAGO
METRO LATE THIS AFTERNOON. NE WINDS TO VEER ENE DURING TONIGHT AND
CONTINUE FRIDAY IN THE 7-10 KT RANGE.
07
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 18Z...
FRIDAY NIGHT THROUGH WEDNESDAY...VFR.
07
&&
.MARINE...
250 AM CDT
LOW PRESSURE OF 29.1 INCHES LIES OVER FAR NORTHERN QUEBEC WITH A
COLD FRONT SAGGING TO THE SOUTHWEST ACROSS THE UPPER PENINSULA OF
MICHIGAN AND INTO CENTRAL WISCONSIN. THIS FRONT WILL CONTINUE TO
MOVE SOUTH ACROSS LAKE MICHIGAN THIS MORNING. THE FRONT SHOULD BE
SOUTH OF LAKE MICHIGAN THIS AFTERNOON AS HIGH PRESSURE OF 30.2
INCHES BUILDS ACROSS THE UPPER MIDWEST. THE HIGH WILL SHIFT EAST
OVER LAKE MICHIGAN ON FRIDAY...THEN OVER THE EASTERN LAKES
SATURDAY. A BROAD AREA OF LOW PRESSURE AVERAGING 29.7 INCHES WILL
DEVELOP OVER THE NORTHERN PLAINS AND CANADIAN PRAIRIES SUNDAY AND
MONDAY...AND SLOWLY SHIFT EAST ACROSS THE GREAT LAKES THROUGH
MIDWEEK.
BMD
&&
.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
1246 PM CDT THU AUG 22 2013
.DISCUSSION...
934 AM...MORNING UPDATE...INCREASED POPS FOR THE ENTIRE AREA
THROUGH EARLY/MID AFTERNOON. LARGE AREA OF SHOWERS WITH EMBEDDED
TSRA CONTINUES TO SLOWLY SAG SOUTH ACROSS THE SOUTHERN CWA.
CONVECTION OVER/ENTERING LASALLE COUNTY WILL HAVE THE HEAVIEST
RAINFALL RATES THAT MAY REACH 1 TO 2 INCHES PER HOUR IN SOME
LOCATIONS. OFF TO THE NORTHWEST...A LINE OF TSRA CONTINUES TO MOVE
EAST ACROSS SOUTHERN WI AND NORTHERN IL. WINDS GUSTED TO 43 KTS AT
KEFT JUST BEFORE THE TOP OF THE HOUR. WHILE STRONG WIND GUSTS WILL
REMAIN POSSIBLE ACROSS FAR NORTHERN IL...NOT ANTICIPATING ANY
WIDESPREAD SEVERE POTENTIAL. THIS COMPLEX IS ASSOCIATED WITH A
SHORTWAVE WHICH EVENTUALLY SLIDES SOUTHEAST ACROSS THE AREA LATE
THIS MORNING INTO EARLY THIS AFTERNOON...THUS EXPECT SHRA/TSRA TO
CONTINUE THROUGH EARLY/MID AFTERNOON AS IT SLIDES SOUTHEAST. HIGH
TEMPERATURES WILL LIKELY BE LOWER THAN CURRENTLY ADVERTISED AND
WILL NEED TO ADJUST THOSE SOON...THOUGH WITH SOME SUNSHINE BY LATE
AFTERNOON...ESPECIALLY ACROSS NORTHERN IL...COULD SEE SOME
RECOVERY BACK INTO THE LOWER 80S. CMS
//PREV DISCUSSION...
329 AM CDT
THE PRIMARY FORECAST CHALLENGES ARE CHANCES FOR STORMS TODAY AND
EARLY THIS EVE FOLLOWED BY THE HEAT...POTENTIALLY
PROLONGED...DURING NEXT WEEK.
THIS MORNING...A SOMEWHAT TRUBULENET...DISORGANIZED...AND EVEN
OVERTURNED ATMOSPHERE IS IN PLACE WITH ONE MCS HAVING GONE
THROUGH LATE LAST NIGHT ACROSS LAKE MI...WITH OUTFLOW STILL
PROGRESSING SOUTHEAST ACROSS THE CWA AS OF 315 AM. THIS IS
TRIGGERING A FEW STORMS THOUGH NOTHING ROBUST. FURTHER WEST AN MCS
EVOLVING EASTWARD ACROSS NORTHERN IA ALONG THE FRONTAL
BOUNDARY...WHICH IS VERY DIFFUSE EARLY TODAY...LOOKS TO WORK
EASTWARD WITHIN THE INSTABILITY MAXIMUM THROUGH THE MORNING. IN
ADVANCE OF THIS...NEAR THE BOUNDARY...THERE HAVE BEEN SOME
ISOLATED STORMS WITHIN THE HIGH PWAT AIR AND GENTLE WARM AIR
ADVECTION BUMPING UP AGAINST THE FRONT. SO ALL OF THIS LIKELY WILL
RESULT IN CONTINUED ISOLATED TO SCATTERED STORM GENERATION THIS
MORNING.
THIS AFTERNOON AND EVENING...WHILE THE IA MCS IS LIKELY TO BEGIN
DECAYING SOME LATER THIS MORNING GIVEN LIMITED DEEP LAYER
SHEAR...REMNANTS OF WHAT IS LEFT ALONG WITH A FORECAST
CONVECTIVELY ENHANCED WAVE BY THE RAP WILL MOVE INTO THE WESTERN
CWA LATE THIS MORNING/EARLY THIS AFTERNOON. THE POTENTIAL FOR THIS
TO RE-INSTIGATE STORMS IS CERTAINLY THERE WITH THE UNSTABLE AIR
MASS STILL IN PLACE AND NOT EXPECTED TO VACATE UNTIL THIS EVE DUE
TO THE SLOW COOL FRONTAL APPROACH FROM THE NORTH. MLCAPE VALUES
OF 1500-3000 J/KG ARE FORECAST BY THE NAM TO BUILD ACROSS THE
WESTERN AND SOUTHERN CWA...BASICALLY IN THOSE AREAS AWAY FROM THE
STABILIZING ONSHORE COMPONENT OFF THE LAKE. GIVEN LITTLE
INHIBITION THE TRIGGER OF THIS IMPULSE/MCV COULD BE ENOUGH TO
SPARK STORMS AND THE SUITE OF CONVECTIVE ALLOWING GUIDANCE HAS
MEMBERS THAT DO JUST THAT. SO HAVE INCREASED POPS SOME INCLUDING
HOLDING ONTO THEM LONGER. COULD CONCEIVABLY SEE SOME STORMS LINGER
INTO THE EVE...NAMELY SOUTH OF I-80. WITH LIMITED UPPER FORCING
AND DYNAMICS THE POTENTIAL FOR ORGANIZATION TOWARD ROBUST STORMS
REMAINS PRIMARILY LOW...THOUGH A FEW ISOLATED NEAR TO SEVERE
STORMS MAY DEVELOP. TEMPERATURES TODAY LOOK TO PEAK IN THE MID 80S
IN THOSE AREAS AWAY FROM THE LAKE WHERE AN ONSHORE COMPONENT WILL
INCREASE THIS AFTERNOON. HIGHS LAKESIDE LOOK TO BE IN THE UPPER
70S.
QUIET WEATHER IS EXPECTED FRI AND SAT WITH HIGHS AROUND NORMAL.
DEW POINTS IN THE 40S STILL LOOK PLAUSIBLE FRI AFTERNOON FOR
SEVERAL AREAS. FRI NIGHT LOOKS CLEAR AND CALM WITH HIGH
CONFIDENCE SO CONTINUE TO ADVERTISE LOWER TO MID 50S IN MOST
OUTLYING AREAS.
NEXT WEEK IS THE FINAL WEEK OF METEOROLOGICAL SUMMER AND IT IS
SHAPING UP TO BE EVERY BIT SUMMER...AT LEAST THE FIRST HALF OF
IT BUT POSSIBLY MUCH OF IT. WITH THE CURRENT TROUGH OVER CANADA
ONLY GIVING A GLANCING BLOW...THE RIDGE BUILDS BACK NORTHWARD
ACROSS THE CENTRAL TO EASTERN PARTS OF THE COUNTRY BY LATE IN THE
WEEKEND. DPROG/DTS FROM BOTH THE EC AND GFS HAVE INDICATED A
FURTHER NORTH 500MB RIDGE CENTER IN THE PAST 24 HOURS...AND THIS
HAS RESULTED IN A WARMING GUIDANCE TREND. THE 594DM RIDGE
PLACEMENT JUST TO THE WEST...MODEST AND WARM SW/WSW 850-925MB
FLOW...AND A DRY COLUMN IS A PATTERN CONDUCIVE FOR WIDESPREAD
LOWER-MID 90S MON AND TUE WITH THE 90 THRESHOLD LIKELY REACHED IN
PLACES ON SUN. THE JET IS ADVERTISED TO BE ACTIVE ON THE NORTH SIDE
OF THIS WITH BROAD LOW PRESSURE ACROSS THE HIGH PLAINS LIKELY
RESULTING IN MULTIPLE MCS DEVELOPMENT IF THIS PATTERN IS CORRECT.
AT THIS TIME...THESE ARE EXPECTED TO REMAIN NORTH BUT DEPENDING ON
FREQUENCY OF THEM LIKELY WILL DICTATE HOW FAR AND QUICKLY SOUTH
THE SURFACE BOUNDARY ADVANCES. WITH NO REAL DEW POINT SCOURING TO
OUR SOUTH FROM OUR CURRENT BOUNDARY...THESE SHOULD REBOUND TO AT
LEAST THE UPPER 60S BY MON AND HOLD TO SLIGHTLY INCREASE AS LONG
AS THE HEAT PERSISTS. BY TUE THIS RESULTS IN FORECAST HEAT INDICES
AT 100 TO 105 IN SOME PLACES /NOT CHICAGO AT THIS TIME/. WHILE
THIS PERIOD IS STILL NUMEROUS DAYS OUT...THERE SEEM TO BE A
LIMITED SET OF FACTORS PRIOR TO WED THAT COULD REALLY BOTCH UP THE
HEAT GIVEN THE AMPLITUDE OF THE RIDGE. WILL CONTINUE TO HIGHLIGHT
IN THE HWO.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* TIMING OF ENDING OF SHOWERS...WITH ASSOCIATED CIG AND VSBY
REDUCTIONS AND TIMING WIND SHIFT AND SPEED.
07
//DISCUSSION...UPDATED 18Z...
MCS WITH WIDESPREAD SHOWERS OVER NORTHEAST IL TO CONTINUE TO
WEAKEN AS IT DRIFTS ESE AND DEPARTS NE IL DURING NEXT FEW HOURS
THROUGH MID AFTERNOON. THUNDERSTORMS SHOULD STAY SOUTH OF I-80 AND
OVER SOUTHERN LAKE MICHIGAN...BUT MODERATE RAIN SHOWERS STILL LIKELY
UNTIL 20Z AT ORD AND MDW WITH MVFR VSBYS AND CEILINGS POSSIBLE.
A COLD FRONT WHICH CURRENTLY STRETCHES FROM GRAND RAPIDS MI WSW TO
JUST NORTH OF CHICAGO TO WATERLOO IA WILL SAG SLOWLY SOUTHWARD
ACROSS THE CHICAGO METRO NEXT 1-3 HOURS THROUGH MID AFTERNOON.
TIMING THE WIND SHIFT WILL BE SOMEWHAT CHALLENGING WITH CURRENT
PROJECTIONS HAVING WEST WINDS 10-15 KTS AND GUSTS 13-18 KTS TO
SHIFT NNW BY 20Z AND NE AFTER 22Z AND DIMINISH TO 5-9 KTS LATE THIS
AFTERNOON AND EARLY EVENING. VFR CIGS OF 3-5K FT POSSIBLE BEHIND
THE FRONT DURING THIS AFTERNOON AND THEN SCATTERED OUT LATER THIS
AFTERNOON WITH BROKEN-OVC MID/HIGH CLOUDS LINGERING INTO THIS
EVENING. MVFR VSBYS WITH LIGHT FOG SHOULD STAY MORE INLAND TOWARD
RFD WHERE ENE WINDS BECOMING LIGHTER BETWEEN 08Z-14Z AND KEPT VFR
VSBYS AT ORD AND MDW. SCATTERED CLOUDS OVERNIGHT INTO FRIDAY WITH
ENE WINDS OF 7-10 KTS.
07
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONIDENCE IN TIMING. WIDESPREAD SHOWERS TO GRADUALLY
DIMINISH FROM THE WEST DURING MID AFTERNOON AROUND 20Z AS MCS
WEAKENS AND TRACKS ESE ACROSS NE IL. POCKETS OF MODERATE RAINS
POSSIBLE TIL 19Z-20Z WITH MVFR CEILINGS/VSBYS THOUGH
THUNDERSTORMS SHOULD STAY SOUTH OF I-80 AND OVER SE LAKE
MICHIGAN.
* MEDIUM CONFIDENCE IN WIND...WEST WINDS AROUND 10 KTS WITH GUSTS
13-18 KTS TO SHIFT NNW BY 20Z AND NE AROUND 22Z AND GRADUALLY
DIMINISH TO 5-9 KTS LATE THIS AFTERNOON AND EARLY EVENING AND
DIMINISH FURTHER AFTER SUNSET AND VEER ENE LATE TONIGHT INTO FRI.
07
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 18Z...
FRIDAY NIGHT THROUGH WEDNESDAY...VFR.
07
&&
.MARINE...
250 AM CDT
LOW PRESSURE OF 29.1 INCHES LIES OVER FAR NORTHERN QUEBEC WITH A
COLD FRONT SAGGING TO THE SOUTHWEST ACROSS THE UPPER PENINSULA OF
MICHIGAN AND INTO CENTRAL WISCONSIN. THIS FRONT WILL CONTINUE TO
MOVE SOUTH ACROSS LAKE MICHIGAN THIS MORNING. THE FRONT SHOULD BE
SOUTH OF LAKE MICHIGAN THIS AFTERNOON AS HIGH PRESSURE OF 30.2
INCHES BUILDS ACROSS THE UPPER MIDWEST. THE HIGH WILL SHIFT EAST
OVER LAKE MICHIGAN ON FRIDAY...THEN OVER THE EASTERN LAKES
SATURDAY. A BROAD AREA OF LOW PRESSURE AVERAGING 29.7 INCHES WILL
DEVELOP OVER THE NORTHERN PLAINS AND CANADIAN PRAIRIES SUNDAY AND
MONDAY...AND SLOWLY SHIFT EAST ACROSS THE GREAT LAKES THROUGH
MIDWEEK.
BMD
&&
.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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WWW.TWITTER.COM/NWSCHICAGO
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AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
111 PM CDT THU AUG 22 2013
.UPDATE...
ISSUED AT 104 PM CDT THU AUG 22 2013
DENSE CI/CS FROM THE MCS IS HOLDING TEMPERATURES DOWN ACROSS MUCH
OF THE AREA. AS A RESULT...MAX TEMPERATURES HAVE BEEN LOWERED
AGAIN. ISOLATED TO SCATTERED SHOWERS WILL PERSIST THROUGH THE
AFTERNOON HOURS. THE MCS TOOL SUGGESTS THE POSSIBILITY OF DIURNAL
CONVECTION DEVELOPING IN RETURN WAA ALOFT ACROSS THE NORTHERN
PARTS OF THE CWFA THAT SLOWLY SINKS SOUTH DURING THE EVENING HOURS.
ANY RAINFALL FROM THIS POINT ONWARD WILL BE VERY SPOTTY. MOST
AREAS WILL REMAIN DRY DURING THE AFTERNOON/EVENING. ..08..
UPDATE ISSUED AT 951 AM CDT THU AUG 22 2013
THE MCS ALONG THE WI/IL BORDER IS STARTING TO DECAY. THE OUTFLOW
BOUNDARY FROM THIS MCS IS DOWN TO I-80 AND WILL DICTATE FUTURE
CONVECTIVE TRENDS.
THE FCST WAS UPDATED TO SHOW MAINLY DRY CONDITIONS ALONG/SOUTH OF
HWY 30. HOWEVER...SINCE THOSE GRIDS WERE DONE NEW CONVECTION HAS
DEVELOPED BETWEEN KALO AND KCID WITH SOME SHRA IN THE
KCID/KDBQ/KMLI TRIANGLE.
NO MODEL IS CURRENTLY HANDLING THE SITUATION VERY WELL. THUS
NOWCASTING TOOLS WILL BE USED HEAVILY. THE MCS TOOL WHEN APPLIED
TO THE CURRENT RAP TRENDS IS SUGGESTING A BULK OF THE AREA WILL
REMAIN DRY TODAY WITH PERHAPS ISOLATED TO SCATTERED CONVECTION
ONCE THE MCS DISSIPATES. ..08..
UPDATE ISSUED AT 646 AM CDT THU AUG 22 2013
I HAVE UPDATED POPS ONCE AGAIN...NOW TO SHARPEN THE CUT FROM
CATEGORICAL NORTH...THE SLIGHT CHANCE ALONG I-80. THIS EVENT
BECOME MORE CHAOTIC THIS AFTERNOON...AND LOW CHANCE POPS ARE
RETAINED FOR MOST OF THE CWA.
ERVIN
&&
.SYNOPSIS...
ISSUED AT 308 AM CDT THU AUG 22 2013
A SLOW MOVING COLD FRONT IS CURRENTLY POSITIONED FROM NORTHERN
NEBRASKA...THROUGH SOUTHERN MINNESOTA AS OF 2 AM. EARLIER...SURFACE
BASED STORMS HAD BEEN PRESENT ALONG THE FRONT FROM NORTH CENTRAL
IOWA THROUGH WISCONSIN...BUT THESE HAVE LONG SINCE DISSIPATED.
ELEVATED CONVECTION IS FOUND IN TWO ZONES...ONE JUST TO THE EAST
OVER NORTHERN ILLINOIS AND INDIANA...AND ANOTHER TO THE WEST. THE
CONVECTION TO THE WEST IS SUPPORTED BY A WEAK SHORT WAVE TROF...AND
IS MUCH MORE ORGANIZED. THIS WESTERN CLUSTER...OR AT LEAST THE SHORT
WAVE ASSOCIATED WITH IT...WILL BE ENTERING OUR CWA TOWARD 12Z TODAY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 308 AM CDT THU AUG 22 2013
WITH THE BOUNDARY OVER THE CWA THROUGH THIS EVENING...IT IS CERTAIN
THAT WHAT EVER CONVECTION MOVES FROM WEST TO EAST ALONG THE FRONT
WILL HIT SOME PORTION OF THE CWA. AS OF NOW...MODELS TAKE A MATURE
MCS EAST THROUGH THE NORTHERN HALF OF THE CWA. THIS SEEMS QUITE
POSSIBLE...BUT GIVEN OUR RECENT STRETCH OF DRY WEATHER...I WILL WAIT
UNTIL IT HOLDS TOGETHER THROUGH CENTRAL IOWA BEFORE GREATLY RAISING
POPS. THE ATMOSPHERE MODESTLY SUPPORTS MAINTENANCE OF THIS
CONVECTIVE CLUSTER TODAY...AND AN UPGRADE FROM LIKELY/CHANCE POPS TO
CATEGORICAL IS QUITE POSSIBLE PRIOR TO 5 AM...BUT AFTER OUR EARLY
MORNING FORECAST ISSUANCE AT 3 AM. AT THIS TIME...IT APPEARS
LOCATIONS GENERALLY ALONG AND NORTH OF HIGHWAY 30...POSSIBLY THROUGH
INTERSTATE 80 STAND TO SEE THE BEST CHANCE OF WIDESPREAD CONVECTION
THIS MORNING. OTHERWISE...WE WILL KEEP CHANCE POPS GOING ALL
AFTERNOON...AND THIS EVENING AS THE FRONTAL BOUNDARY IS OVERHEAD.
SOME ELEVATED CELLS ARE AGAIN POSSIBLE OVERNIGHT TONIGHT...BUT THESE
SHOULD GENERALLY BE UNORGANIZED...AND TIED TO THE SOUTHWESTERN CWA.
TEMPERATURES TODAY WILL HAVE TO DEAL WITH PLENTY OF CLOUDS AND
POSSIBLY WIDESPREAD RAINFALL...THUS LOWER 80S NORTH TO UPPER 80S
SOUTH SEEM THE SAFEST BET FOR HIGHS. TONIGHTS LOWS UNDER SOME CLOUD
COVER...ARE LIKELY TO BE A BIT WARMER THAN EARLIER FORECAST. FOR NOW
AM THINKING UPPER 50S NORTHEAST TO UPPER 60S SOUTHWEST.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 335 AM CDT THU AUG 22 2013
THE EXTENDED FORECAST IN A NUTSHELL...HOT...HUMID...AND DRY. THE
PERIOD WILL BE DOMINATED BY A BUILDING UPPER LEVEL RIDGE OVER THE
NATIONS MIDSECTION WHICH WILL STRENGTHEN INTO NEXT WEEK...RESULTING
IN DRY CONDITIONS...AND A POSSIBLY A PROLONGED HEAT WAVE. OTHER THAN
A VERY SLIGHT CHANCE OF POPS IN THE SW FOR FRI AS AN 850MB MOISTURE
LINGERS OVER THE AREA...THE EXTENDED LOOKS DRY. HIGHS FRI WILL BE
IN THE LOWER 80S NORTH...TO UPPER 80S SOUTH. SLIGHTLY WARMER TEMPS
ARE ON TAP FOR SAT...WITH READINGS IN THE MID 80S NE TO NEAR 90 SW.
WE THEN TURN UP THE BURNER FOR SUNDAY THROUGH WEDNESDAY...AS 850
TEMPS WARM INTO THE LOW-MID 20S...TRANSLATING TO HIGHS EACH DAY IN
THE LOWER TO MIDDLE 90S...WHICH MAY APPROACH RECORD LEVELS.
HUMIDITY LEVELS WILL ALSO INCREASE DURING THIS TIME...WITH DEW
POINTS IN THE UPPER 60S TO LOW 70S. OVERNIGHT LOWS SUN THROUGH WED
WILL BE IN THE LOW-MID 70...ALSO POSSIBLE RECORD WARM LOWS. DAYTIME
HEAT INDICES WILL BE IN THE MID 90S TO AROUND 100. THE REAL HEAT
DOME IS STILL WEST OUT OVER THE PLAINS...INDICATING NO REAL SIGNS OF
THE HEAT WAVE BREAKING ANY TIME SOON. STILL TOO SOON TO ISSUE HEAT
HEADLINE PRODUCTS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 104 PM CDT THU AUG 22 2013
GENERALLY VFR WX WITH ISOLATED TO SCATTERED SHRA AND POSSIBLY A
TSRA WILL BE SEEN ACROSS EASTERN IOWA AND NORTHERN ILLINOIS
THROUGH 00Z/23. A BRIEF PERIOD OF MVFR CONDITIONS MAY BE SEEN IF A
SHRA OR TSRA AFFECTS A TAF SITE. AFT 00Z/23 MAINLY VFR WX WILL BE
SEEN AS HIGH PRESSURE BUILDS INTO THE GREAT LAKES BUT POCKETS OF
MVFR CONDITIONS ARE POSSIBLE. KDBQ HAS A STRONG PROBABILITY OF
DVLPG IFR CONDITIONS PRIOR TO SUNRISE DUE TO WET GROUND AND LIGHT
WINDS. THE POTENTIAL DOES EXIST FOR LIFR/VLIFR CONDITIONS AT KDBQ.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...14
AVIATION...08
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1030 AM MDT THU AUG 22 2013
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 248 AM MDT THU AUG 22 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW BROAD RIDGE STILL IN
PLACE ACROSS THE SOUTHERN PLAINS...WITH ACTIVE ZONAL FLOW ACROSS
THE NORTHERN PLAINS. SEVERAL SHORTWAVE TROUGHS ARE IN PLACE WITHIN
THE MEAN FLOW OVER CENTRAL NEBRASKA AND WESTERN WYOMING. AT THE
SURFACE A COLD FRONT HAS PUSHED SOUTH OVER OUR CWA AND IS
CURRENTLY EXTENDING FRONT NORTON TO CHEYENNE WELLS BEFORE TURNING
BACK TO THE NORTH ALONG THE THE FRONT RANGE IN COLORADO.
THUNDERSTORMS DEVELOPED OVERNIGHT AHEAD OF THIS FRONT IN THE FAR
EASTERN PART OF THE CWA...WITH SUPPORT FROM H85 50KT JET AND
STRONG THETA-E CONVERGENCE IN THE H85-H7 LAYER. SHORT RANGE
GUIDANCE SUPPORTS THIS ACTIVITY PULLING OFF THE EAST THROUGH
SUNRISE...HOWEVER LITTLE WILL CHANGE REGARDING INSTABILITY/FORCING
SO WILL NEED TO MONITOR/REEVALUATE IF I NEED TO KEEP POPS MENTION
BEYOND 15Z FOR THESE LOCATIONS. ADDITIONAL THUNDERSTORM IS
EXPECTED TO DEVELOP THIS AFTERNOON GENERALLY ALONG THE THE STALLED
FRONT...WITH ADDITIONAL FORCING IN THE LATE AFTERNOON THROUGH
EVENING ASSOCIATED WITH SHORTWAVE TROUGH PASSAGE IN NEBRASKA. WITH
FRONT OVER OUR CWA WE SHOULD SEE BETTER COVERAGE ALONG
FRONT. BETTER INSTABILITY GENERALLY TO THE NORTH OF THE FRONT
WHERE TD VALUES IN THE 60S WILL BE...SO I KEPT CHANCE POPS
GENERALLY OVER THE NW CWA. NAM/RAP BOTH SHOW SB/ML CAPE IN EXCESS
OF 2000 J/KG NORTH OF THIS FRONT WHICH COULD CERTAINLY SUPPORT
STRONG UPDRAFTS. SHEER ON THE OTHER HAND IS NOT QUITE AS
STRONG (0-6KM 20-25KT). THERE DOES APPEAR TO BE ENOUGH SUPPORT FOR
AN ELEVATED LARGE HAIL/STRONG WIND THREAT WITH THUNDERSTORMS THAT
DEVELOP.
AFTER TOMORROW NIGHT PRECIP CHANCES DECREASE SIGNIFICANTLY WITH
INCREASING CAP AND STRONGER SUBSIDENCE ASSOCIATED WITH BUILDING
RIDGE. THERE IS SOME INDICATION OF THUNDERSTORMS MOVING INTO THE
FAR NW PART OF THE CWA FRIDAY AFTERNOON/EVENING...SO I ADDED
SLIGHT CHANCE POPS. BY SATURDAY THE MEAN STORM TRACK WILL HAVE
SHIFTED FAR ENOUGH NORTH WITH STRONG CINH AND LARGE SCALE
SUBSIDENCE INHIBITING AFTERNOON/EVENING CHANCES.
TEMPS WILL DROP CLOSER TO SEASONAL NORMS TODAY BEHIND FRONT IN
THE UPPER 80S/LOW 90S. TH TREND WILL BE MUCH ABOVE NORMAL FRIDAY
AND SATURDAY WITH STRONG RIDGE (595DM) AND STRONG WAA ASSOCIATED
WITH SOUTHERLY FLOW EAST OF STRENGTHENING LEE TROUGH. HAVE TRENDED
TEMPS TOWARDS UPPER 90S BASED ON MIXING WED...AND MIGHT BE A FEW
DEGREES TOO COOL WITH TEMPS NEAR 100F NOT OUT OF THE QUESTION.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 248 AM MDT THU AUG 22 2013
FORECAST PATTERN FOR THE WEEKEND AND EARLY NEXT WEEK HAS CHANGED
LITTLE OVER THE PAST FEW DAYS. A STRONG UPPER-LEVEL RIDGE WILL BE
CENTERED OVER THE CENTRAL PLAINS FOR MUCH OF THE PERIOD...WITH THE
GEM AND ECMWF PLACING THE UPPER HIGH JUST EAST OF THE CENTRAL
PLAINS. WHILE THE RIDGE IS IN PLACE PRECIP CHANCES WILL BE NEAR-NIL
AS DISTURBANCES ROTATE AROUND THE RIDGE. TEMPS WILL BE WELL ABOVE
NORMAL WITH 850MB TEMPS IN THE LOW 30S C...TRANSLATING TO HIGHS IN
THE MID TO UPPER 90S. WOULD NOT BE SURPRISED TO SEE SOME SPOTS HIT
THE TRIPLE DIGITS MON OR TUES...THE HEAT PEAKING AROUND TUESDAY
BEFORE THE RIDGE SHIFTS A BIT FURTHER EAST INTO THE MIDDLE OF THE
WEEK. WINDS DURING THE PERIOD WILL BE PRETTY BREEZY OUT OF THE
SOUTH AT 15 TO 20 MPH DURING THE AFTERNOONS AS A NORTH-SOUTH
ORIENTED SURFACE TROUGH DEVELOPS IN EASTERN COLORADO.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1030 AM MDT THU AUG 22 2013
FOR KGLD AND KMCK VFR EXPECTED THROUGH THE PERIOD. GUSTY POST
FRONTAL NORTHEAST WINDS OF 15-20KTS AT TAF ISSUANCE WILL GRADUALLY
VEER TO THE NORTHEAST AND EAST THROUGH THE REST OF THE DAY WITH
SPEEDS SLOWLY DECREASING. FOR TONIGHT WINDS WILL BE LIGHT. FOR
FRIDAY LIGHT WINDS BECOME SOUTHEAST AT 12-13KTS WITH GUSTS AROUND
20KTS (KGLD) TOWARD THE END OF THE TAF PERIOD. ONLY MID AND HIGH
CLOUDS EXPECTED. MAY SEE A FEW SHOWERS AND THUNDERSTORMS THIS
AFTERNOON INTO EARLY EVENING BUT COVERAGE SHOULD BE RATHER LIMITED
AND CONFIDENCE TOO LOW TO INCLUDE IN TAFS AT PRESENT TIME.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...JJM
AVIATION...99
AREA FORECAST DISCUSSION
NWS JACKSON KY
338 PM EDT THU AUG 22 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 337 PM EDT THU AUG 22 2013
ISOLATED TO SCATTERED CONVECTION ACROSS THE AREA HAS REMAINED
UNORGANIZED AND TAME SO FAR TODAY...WITH LITTLE UPPER LEVEL SUPPORT
AVAILABLE. A SHORT WAVE ON WATER VAPOR IMAGERY OVER THE UPPER MS
VALLEY IS MOVING ESE...WHILE AN OLD OUTFLOW BOUNDARY AT THE SURFACE
IS FOCUSING CONVECTIVE DEVELOPMENT ACROSS CENTRAL OH AND INDIANA.
AS THE SHORT WAVE MOVES INTO THE OH VALLEY TONIGHT...THERE WILL BE
BETTER UPPER LEVEL SUPPORT FOR PRECIPITATION ACROSS THE FORECAST
AREA. THE EXACT EVOLUTION OF CONVECTION DEVELOPING ACROSS OH AND
INDIANA IS UNCERTAIN...AND THE 17Z HRRR HAS MOST PRECIPITATION DYING
OUT BY 02Z. HOWEVER IT DOES SHOW REDEVELOPMENT AROUND 05Z MOST
LIKELY IN ASSOCIATION WITH AN UPPER LEVEL SPEED MAX ASSOCIATED WITH
THE UPPER TROF. THE NAM IS MOST SUPPORTIVE OF PRECIPITATION
OVERNIGHT...BUT THE GFS...ECMWF AND GEM ALL POINT TOWARDS A CHANCE
OF SHOWERS AND THUNDERSTORMS. IT DOES APPEAR THE BEST SUPPORT WILL BE
OVER THE NORTHERN AND EASTERN PORTION OF THE FORECAST AREA AND HAVE
ELECTED TO GO WITH LIKELY PROBABILITY OF RAIN CHANCES IN THESE AREAS
WITH A CHANCE IN THE SOUTHWEST. WEAK COLD FRONT WILL NOT CLEAR THE
AREA UNTIL FRIDAY EVENING...SO WILL CONTINUE WITH A CHANCE OF SHOWERS
AND THUNDERSTORMS FRIDAY...BUT DECREASE CHANCES FROM THE NORTH DURING
THE DAY.
WITH PRECIPITABLE WATER AROUND 1.9 INCHES OR NEAR THE 90TH
PERCENTILE...WILL CONTINUE TO MENTION HEAVY RAIN AND FLASH FLOOD
POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK FOR TONIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 337 PM EDT THU AUG 22 2013
OT A LOT OF CHANGE FROM PREVIOUS FORECAST. MODELS ARE STILL IN
RELATIVELY GOOD AGREEMENT THAT THE UPPER AIR PATTERN WILL CONSIST OF
A LARGE 500MB RIDGE ACROSS THE SOUTH CENTRAL CONUS...EXPECTED TO
REMAIN IN PLACE THROUGH THE DURATION OF THE FORECAST PERIOD. WITH
UPPER LEVEL TROUGHING OFF BOTH THE NW AND NE COAST...EASTERN KY WILL
FIND ITSELF WITHIN THE RIDGING PATTERN...BUT ON THE WINDWARD SIDE OF
THE NE TROUGHING PATTERN. ANY SHORTWAVE THAT TRAVELS ALONG THE
TROUGH AXIS WILL MAKE ITS WAY NEAR EASTERN KY DESPITE THE STRONG
RIDGING IN PLACE. HOWEVER...WITH SOMEWHAT LESS AGREEMENT ON THE
SMALLER SCALE...ANY SHORTWAVES AND RESULTING RAIN CHANCES WILL BE
BEST LEFT TO A MODEL CONSENSUS.
WITH A GOOD VEERING WIND PROFILE...AND TEMPERATURES EXPECTED TO BE
WARMER AND MORE HUMID THAN HAVE BEEN OVER THE PAST FEW WEEKS...ALL
MODELS ARE POINTING AT THE POTENTIAL FOR AFTERNOON INSTABILITY AND
CONVECTION ACROSS THE EASTERN PORTION OF THE STATE THROUGH THE
ENTIRE FORECAST PERIOD. THE ONLY CAVEAT TO THIS IS THE FACT THAT
GFS40 SOUNDINGS /BOTH CURRENT AND PREVIOUS/ ARE SHOWING AN ABUNDANT
AMOUNT OF DRY AIR AT ALL LEVELS...WITH ONLY THE POTENTIAL FOR A SCT
THIN LAYER OF DIURNAL CLOUDS. AND THOUGH THERE IS A GOOD VEERING
PATTERN MENTIONED ABOVE...MOST OF THIS TAKES PLACE IN THE MID LEVELS
RATHER THAN THE LOWER LEVELS...WITH A LOW AMOUNT OF CAPE AND A VERY
LIMITED AMOUNT OF TIME IN THE AFTERNOON WHERE THERE IS NOT A CAPPING
INVERSION. ALL THINGS CONSIDERED...DID PUT IN SOME SLIGHT CHANCE
POPS IN THE AFTERNOON TO GO ALONG WITH MODEL CONSENSUS...BUT EXPECT
THUNDERSTORM DEVELOPMENT TO BE EVEN MORE ISOLATED IN COMPARISON TO
SHOWER POTENTIAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 140 PM EDT THU AUG 22 2013
ISOLATED TO SCATTERED THUNDERSTORMS WILL OCCUR ACROSS THE FORECAST
AREA THIS AFTERNOON...WITH THE MOST WIDESPREAD RAINFALL COVERAGE
EXPECTED TONIGHT AS A COLD FRONT SAGS SOUTH ACROSS OH AND INDIANA
AND INTO KY. OUTSIDE OF SHOWERS AND THUNDERSTORMS VFR CONDITIONS WILL
PREVAIL THIS AFTERNOON...BUT THROUGH MID AFTERNOON THERE WILL BE
SOME AREAS OF MVFR CEILINGS. AFTER MORE WIDESPREAD RAINFALL TONIGHT...
CEILINGS AND VISIBILITIES ARE EXPECTED TO LOWER TO IFR. CEILINGS AND
VISIBILITIES WILL GRADUALLY IMPROVE THROUGH THE MORNING ON FRIDAY.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SBH
LONG TERM...JMW
AVIATION...SBH
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
551 PM EDT THU AUG 22 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION TONIGHT AND WILL BE FOLLOWED BY
HIGH PRESSURE BUILDING IN FROM THE WEST ON FRIDAY. HIGH PRESSURE
WILL CREST OVER THE REGION ON SATURDAY AND WILL SETTLE SOUTH OF THE
REGION ON SUNDAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST ON
MONDAY AND WILL CROSS THE REGION LATE MONDAY NIGHT AND EARLY
TUESDAY. A WEAK RIDGE OF HIGH PRESSURE WILL BUILD IN BEHIND THE
FRONT TUESDAY AFTERNOON. LOW PRESSURE WILL PASS SOUTHWEST OF THE
FORECAST AREA WEDNESDAY. A WEAK COLD FRONT WILL DROP SOUTH INTO THE
REGION WEDNESDAY NIGHT AND WILL STALL OVER THE AREA ON THURSDAY.
&&
.NEAR TERM /THROUGH FRIDAY/...
UPDATE...HAVE USED THE 19Z HRRR RUN TO TREND POP FOR THE NEXT
SEVERAL HOURS. IT HAS A GOOD HANDLE ON CURRENT CONVECTION...AS
WELL AS EVOLUTION. IT SHOWS A GENERAL WEAKENING TREND OVER THE
NEXT COUPLE OF HOURS...AND BASED ON LIGHTNING OBS AND CLOUD TOP
WARMING THIS APPEARS TO BE THE CASE. THE ALREADY LOW PROB OF
SEVERE WX WILL CONTINUE TO DECLINE AS WE/VE PASSED THE PEAK IN
DIURNAL HEATING.
PREVIOUS DISCUSSION...STRONG SHORT WAVE TROUGH CONTINUES TO PUSH
ACROSS THE NORTHERN GREAT LAKES. ATTENDANT SFC COLD FRONT
CONTINUES TO MOVE EASTWARD IN ADVANCE OF THE SHORT WAVE TROUGH
ACROSS EASTERNMOST ONTARIO AND SOUTHERN QUEBEC. SHOWERS AND
THUNDERSTORMS HAVE DEVELOPED IN ADVANCE OF THE COLD FRONT IN
NORTHERNMOST NY AND NORTHWESTERN VT. A FEW STORMS HAVE ALSO
DEVELOPED NEAR THE SOMERSET/PISCATAQUIS COUNTY BORDER IN MAINE AND
ARE MOVING EAST.
AS THE COLD FRONT CONTINUES TO MARCH EASTWARD OVER THE NEXT
SEVERAL HOURS...THE SHOWERS AND STORMS OVER NORTHERN NY AND VT
WILL MOVE EASTWARD INTO NORTHERN NH AND THE WESTERN ME MOUNTAINS.
WHILE DEEP LAYER SHEAR IS QUITE WEAK...ENOUGH INSTABILITY EXISTS
IN TANDEM WITH 20-30 DEGREE SFC DEWPOINT DEPRESSIONS TO ALLOW FOR
A LOW PROB OF ISOLATED STRONG TO DAMAGING WIND GUSTS WITH THIS
ACTIVITY LATE THIS AFTERNOON INTO THE EARLY EVENING HOURS. HIGHEST
POPS HAVE BEEN PLACED IN THIS AREA...MAINLY NORTH OF A LEBANON NH-
SKOWHEGAN ME LINE.
FURTHER SOUTH...ACTIVITY LOOKS TO REMAIN A LOT MORE ISOLATED. THE
ONLY CAVEAT IS IF A LINE OF SHOWERS AND STORMS DEVELOPS ON THE
NOSE OF THE SHORT WAVE TROUGH AND SFC COLD FRONT AND MOVES ACROSS
THE AREA LATE THIS EVENING TO JUST AFTER MIDNIGHT. THE LATEST FEW
RUNS OF THE HRRR HAS SUGGESTED THIS. GIVEN THE STRENGTH OF THE
FORCING...HAVE INCREASED POPS TO ACCOUNT FOR THIS POSSIBILITY
AFTER DARK. JUST WINDS AND HEAVY DOWNPOURS WILL REMAIN POSSIBLE
WITH THIS ACTIVITY. ANY PRECIPITATION SHOULD SWEEP OFFSHORE BEFORE
DAWN.
&&
.SHORT TERM /FRIDAY NIGHT/...
DEEP UPPER TROUGH MOVES ACROSS THE AREA ON FRIDAY. SO EVEN THOUGH
SFC HIGH PRESSURE MOVES INTO THE AREA...THERE SHOULD BE PLENTY OF
STRATOCU AROUND...AS WELL AS THE SLIGHT CHANCE OF SHOWERS AND
PERHAPS A SPRINKLE.
HIGH PRESSURE CONTINUES TO MOVE IN FRIDAY NIGHT. SKIES SHOULD
CLEAR IN THE EVENING AND WINDS SHOULD GO CALM. THIS WILL LEAD TO
STRONG RADIATIONAL COOLING...WITH A FEW AREAS IN NORTHERN NH
POSSIBLY DROPPING INTO THE MID 30S. SCATTERED FROST?
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BUILD OVER NEW ENGLAND SATURDAY AND WILL
GRADUALLY SETTLE SOUTH OF THE REGION ON SUNDAY. BOTH DAYS LOOKING
VERY NICE WITH ABUNDANT SUNSHINE AND LIGHT WINDS. SHOULD SEE HIGHS
SATURDAY RANGING THROUGH THE 70S FROM NORTH TO SOUTH. WILL TACK ON A
DEGREE OR TWO ON SUNDAY. SATURDAY NIGHT LOOKING PRETTY CHILLY WITH
SOME MOUNTAIN VALLEYS DIPPING INTO THE UPPER 30S. SOUTHERN AREAS
WILL RANGE FROM THE MID 40S TO LOWER 50S ALONG THE COAST.
A COLD FRONT WILL APPROACH FROM THE NORTHWEST ON MONDAY BUT MOST OF
THE DAY WILL BE SUNNY WITH INCREASING HUMIDITY. TEMPERATURES WILL
ALSO BE ON THE INCREASE WITH MOST AREAS AWAY FROM THE COAST GETTING
INTO THE LOWER TO MID 80S. WILL SEE INCREASING CLOUDS IN NORTHWEST
ZONES DURING THE LATTER HALF OF THE AFTERNOON WITH A CHANCE OF A
SHOWER OR THUNDERSTORM BY EVENING.
COLD FRONT WILL SWING THROUGH MONDAY NIGHT AND EARLY TUESDAY
BRINGING A ROUND SHOWERS AND THUNDERSTORMS TO THE AREA. AFTER A
CLOUDY START TO THE DAY WILL SEE GRADUAL CLEARING FROM EAST TO WEST
IN THE AFTERNOON. NOT A BIG PUSH OF COLD AIR BEHIND THE FRONT SO
WILL SEE HIGHS FROM THE MID 70S TO LOWER 80S.
WEAK RIDGE OF HIGH PRESSURE BUILDS IN FROM THE WEST TUESDAY NIGHT AS
LOW PRESSURE APPROACHES FROM THE WEST. LOW PRESSURE FORECAST TO PASS
SOUTHWEST OF THE REGION ON WEDNESDAY. WILL SEE VARIABLE CLOUDINESS
DURING THE DAY BUT AT THIS POINT LOOKS LIKE ANY PRECIP REMAINS SOUTH
OF THE FORECAST AREA ACROSS SOUTHERN NEW ENGLAND.
LOW PRESSURE HEADS OUT TO SEA WEDNESDAY NIGHT AS A WEAK COLD FRONT
DROPS SOUTH INTO NORTHERN ZONES. WILL SEE A CHANCE OF A SHOWER OR
THUNDERSTORM BOTH WEDNESDAY NIGHT AND THURSDAY AS THIS BOUNDARY
STALLS OVER THE REGION.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
SHORT TERM...LOCAL MVFR OR LOWER CONDITIONS IN SHOWERS AND
THUNDERSTORMS POSSIBLY THROUGH MIDNIGHT TONIGHT...THEN VFR
CONDITIONS EXPECTED LATE TONIGHT THROUGH FRIDAY NIGHT. VALLEY FOG
LIKELY LATE FRIDAY NIGHT.
LONG TERM...VFR SATURDAY THROUGH MONDAY. AREAS MVFR/IFR CEILINGS
MONDAY NIGHT. VFR TUESDAY.
&&
.MARINE...
SHORT TERM...MARGINAL SCA POSSIBLE TONIGHT INTO FRIDAY WITH A FEW
5 FOOTERS POSSIBLE ON THE OCEAN. HOWEVER...HAVE HELD OFF ON ANY
SCA FOR NOW SINCE MODELS TEND TO BE OVERDOING THE SEAS A BIT AT
THE MOMENT.
LONG TERM...SCA`S LIKELY NEEDED ON MONDAY AND MONDAY NIGHT.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...LEGRO
AREA FORECAST DISCUSSION
NWS GRAY ME
244 PM EDT THU AUG 22 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION TONIGHT AND WILL BE FOLLOWED BY
HIGH PRESSURE BUILDING IN FROM THE WEST ON FRIDAY. HIGH PRESSURE
WILL CREST OVER THE REGION ON SATURDAY AND WILL SETTLE SOUTH OF THE
REGION ON SUNDAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST ON
MONDAY AND WILL CROSS THE REGION LATE MONDAY NIGHT AND EARLY
TUESDAY. A WEAK RIDGE OF HIGH PRESSURE WILL BUILD IN BEHIND THE
FRONT TUESDAY AFTERNOON. LOW PRESSURE WILL PASS SOUTHWEST OF THE
FORECAST AREA WEDNESDAY. A WEAK COLD FRONT WILL DROP SOUTH INTO THE
REGION WEDNESDAY NIGHT AND WILL STALL OVER THE AREA ON THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
STRONG SHORT WAVE TROUGH CONTINUES TO PUSH ACROSS THE NORTHERN
GREAT LAKES. ATTENDANT SFC COLD FRONT CONTINUES TO MOVE EASTWARD
IN ADVANCE OF THE SHORT WAVE TROUGH ACROSS EASTERNMOST ONTARIO AND
SOUTHERN QUEBEC. SHOWERS AND THUNDERSTORMS HAVE DEVELOPED IN
ADVANCE OF THE COLD FRONT IN NORTHERNMOST NY AND NORTHWESTERN VT.
A FEW STORMS HAVE ALSO DEVELOPED NEAR THE SOMERSET/PISCATAQUIS
COUNTY BORDER IN MAINE AND ARE MOVING EAST.
AS THE COLD FRONT CONTINUES TO MARCH EASTWARD OVER THE NEXT
SEVERAL HOURS...THE SHOWERS AND STORMS OVER NORTHERN NY AND VT
WILL MOVE EASTWARD INTO NORTHERN NH AND THE WESTERN ME MOUNTAINS.
WHILE DEEP LAYER SHEAR IS QUITE WEAK...ENOUGH INSTABILITY EXISTS
IN TANDEM WITH 20-30 DEGREE SFC DEWPOINT DEPRESSIONS TO ALLOW FOR
A LOW PROB OF ISOLATED STRONG TO DAMAGING WIND GUSTS WITH THIS
ACTIVITY LATE THIS AFTERNOON INTO THE EARLY EVENING HOURS. HIGHEST
POPS HAVE BEEN PLACED IN THIS AREA...MAINLY NORTH OF A LEBANON NH-
SKOWHEGAN ME LINE.
FURTHER SOUTH...ACTIVITY LOOKS TO REMAIN A LOT MORE ISOLATED. THE
ONLY CAVEAT IS IF A LINE OF SHOWERS AND STORMS DEVELOPS ON THE
NOSE OF THE SHORT WAVE TROUGH AND SFC COLD FRONT AND MOVES ACROSS
THE AREA LATE THIS EVENING TO JUST AFTER MIDNIGHT. THE LATEST FEW
RUNS OF THE HRRR HAS SUGGESTED THIS. GIVEN THE STRENGTH OF THE
FORCING...HAVE INCREASED POPS TO ACCOUNT FOR THIS POSSIBILITY
AFTER DARK. JUST WINDS AND HEAVY DOWNPOURS WILL REMAIN POSSIBLE
WITH THIS ACTIVITY. ANY PRECIPITATION SHOULD SWEEP OFFSHORE BEFORE
DAWN.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
DEEP UPPER TROUGH MOVES ACROSS THE AREA ON FRIDAY. SO EVEN THOUGH
SFC HIGH PRESSURE MOVES INTO THE AREA...THERE SHOULD BE PLENTY OF
STRATOCU AROUND...AS WELL AS THE SLIGHT CHANCE OF SHOWERS AND
PERHAPS A SPRINKLE.
HIGH PRESSURE CONTINUES TO MOVE IN FRIDAY NIGHT. SKIES SHOULD
CLEAR IN THE EVENING AND WINDS SHOULD GO CALM. THIS WILL LEAD TO
STRONG RADIATIONAL COOLING...WITH A FEW AREAS IN NORTHERN NH
POSSIBLY DROPPING INTO THE MID 30S. SCATTERED FROST?
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BUILD OVER NEW ENGLAND SATURDAY AND WILL
GRADUALLY SETTLE SOUTH OF THE REGION ON SUNDAY. BOTH DAYS LOOKING
VERY NICE WITH ABUNDANT SUNSHINE AND LIGHT WINDS. SHOULD SEE HIGHS
SATURDAY RANGING THROUGH THE 70S FROM NORTH TO SOUTH. WILL TACK ON A
DEGREE OR TWO ON SUNDAY. SATURDAY NIGHT LOOKING PRETTY CHILLY WITH
SOME MOUNTAIN VALLEYS DIPPING INTO THE UPPER 30S. SOUTHERN AREAS
WILL RANGE FROM THE MID 40S TO LOWER 50S ALONG THE COAST.
A COLD FRONT WILL APPROACH FROM THE NORTHWEST ON MONDAY BUT MOST OF
THE DAY WILL BE SUNNY WITH INCREASING HUMIDITY. TEMPERATURES WILL
ALSO BE ON THE INCREASE WITH MOST AREAS AWAY FROM THE COAST GETTING
INTO THE LOWER TO MID 80S. WILL SEE INCREASING CLOUDS IN NORTHWEST
ZONES DURING THE LATTER HALF OF THE AFTERNOON WITH A CHANCE OF A
SHOWER OR THUNDERSTORM BY EVENING.
COLD FRONT WILL SWING THROUGH MONDAY NIGHT AND EARLY TUESDAY
BRINGING A ROUND SHOWERS AND THUNDERSTORMS TO THE AREA. AFTER A
CLOUDY START TO THE DAY WILL SEE GRADUAL CLEARING FROM EAST TO WEST
IN THE AFTERNOON. NOT A BIG PUSH OF COLD AIR BEHIND THE FRONT SO
WILL SEE HIGHS FROM THE MID 70S TO LOWER 80S.
WEAK RIDGE OF HIGH PRESSURE BUILDS IN FROM THE WEST TUESDAY NIGHT AS
LOW PRESSURE APPROACHES FROM THE WEST. LOW PRESSURE FORECAST TO PASS
SOUTHWEST OF THE REGION ON WEDNESDAY. WILL SEE VARIABLE CLOUDINESS
DURING THE DAY BUT AT THIS POINT LOOKS LIKE ANY PRECIP REMAINS SOUTH
OF THE FORECAST AREA ACROSS SOUTHERN NEW ENGLAND.
LOW PRESSURE HEADS OUT TO SEA WEDNESDAY NIGHT AS A WEAK COLD FRONT
DROPS SOUTH INTO NORTHERN ZONES. WILL SEE A CHANCE OF A SHOWER OR
THUNDERSTORM BOTH WEDNESDAY NIGHT AND THURSDAY AS THIS BOUNDARY
STALLS OVER THE REGION.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
SHORT TERM...LOCAL MVFR OR LOWER CONDITIONS IN SHOWERS AND
THUNDERSTORMS POSSIBLY THROUGH MIDNIGHT TONIGHT...THEN VFR
CONDITIONS EXPECTED LATE TONIGHT THROUGH FRIDAY NIGHT. VALLEY FOG
LIKELY LATE FRIDAY NIGHT.
LONG TERM...VFR SATURDAY THROUGH MONDAY. AREAS MVFR/IFR CEILINGS
MONDAY NIGHT. VFR TUESDAY.
&&
.MARINE...
SHORT TERM...MARGINAL SCA POSSIBLE TONIGHT INTO FRIDAY WITH A FEW
5 FOOTERS POSSIBLE ON THE OCEAN. HOWEVER...HAVE HELD OFF ON ANY
SCA FOR NOW SINCE MODELS TEND TO BE OVERDOING THE SEAS A BIT AT
THE MOMENT.
LONG TERM...SCA`S LIKELY NEEDED ON MONDAY AND MONDAY NIGHT.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
NEAR/SHORT TERM...EKSTER
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
203 PM EDT THU AUG 22 2013
.SYNOPSIS...
SHOWERS WILL BE LIKELY AS A COLD FRONT CROSSES THE AREA THROUGH
FRIDAY MORNING.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SHOWERS HAVE REALLY TAKEN THEIR TIME GETTING THEIR ACT TOGETHER.
SHOWERS HAVE FINALLY REDEVELOPED TO THE NORTH AND EAST OF
PITTSBURGH...WHILE LINE HAS GENERALLY HELD TOGETHER FROM THE
WESTERN LAKE ERIE SHORELINE AS IT MOVED INTO EASTERN OHIO AND THE
NORTHERN WEST VIRGINIA PANHANDLE. HAVE CHANGED POPS FOR TIMING OF
PRECIPITATION BASED ON RADAR TRENDS. THAT BEING SAID...AREAS SUCH
AS MERCER AND VENANGO COUNTY MAY REMAIN COMPLETELY DRY. THE LAST
FEW RUNS OF THE HRRR ATTEMPT TO HAVE ANOTHER LINE OF SHOWERS
DEVELOP ACROSS THE INTERSTATE 80 CORRIDOR WITH THE ACTUAL FRONTAL
PASSAGE LATE THIS AFTERNOON...BUT THE HRRR ALSO INDICATED THAT THE
CURRENT LINE OF SHOWERS WAS GOING TO HANG TOGETHER ALONG THE I-80
CORRIDOR WHICH DID NOT HAPPEN. HAVE STILL KEPT POPS GOING THROUGH
THE AFTERNOON HOURS IN ALL LOCATIONS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
SOUTHWARD IMPETUS FOR THE TRANSLATION OF THE FRONT SEEMS LIKE IT
SLOWLY FADES GOING INTO TONIGHT AND ESPECIALLY FRIDAY MORNING AS
THE MID-LEVEL FORCING ASSOCIATED WITH THE SYSTEM WILL HAVE ALREADY
SCREAMED EASTWARD INTO SOUTHERN QUEBEC AND MARITIME CANADA BY
FRIDAY MORNING. THIS LEAVES THE FRONT`S FORWARD PROGRESS TO SLOW
FAIRLY RAPIDLY AS IT STARTS TO LOSE DEFINITION THROUGH FRIDAY
MORNING. WITH THE FRONT HUNG UP...BOTH THE GFS AND NAM LIKE THE
IDEA OF RUNNING A SECONDARY VORT DOWN THE BOUNDARY LATE TONIGHT
INTO FRIDAY MORNING THAT MANAGES TO CLIP THE SOUTHERN AND
ESPECIALLY SOUTHEASTERN PORTIONS OF THE FORECAST AREA. DEEP LAYER
WESTERLY FLOW COMBINED WITH INSTABILITY AS WELL AS THE INTERACTION
WITH THE RIGHT ENTRANCE REGION OF THE UPPER JET THAT WILL BE
SITUATED OVER NORTHERN PENNSYLVANIA BY THAT TIME SHOULD ALLOW FOR
FAIRLY WIDESPREAD SHOWER DEVELOPMENT OVERNIGHT INTO FRIDAY MORNING
ACROSS THE SOUTHEASTERN ZONES. POPS WERE INCREASED SUBSTANTIALLY
IN THIS AREA TO ACCOUNT FOR BOTH LARGE SCALE AS WELL AS OROGRAPHIC
PRECIPITATION ENHANCEMENT.
BY FRIDAY AFTERNOON...EVEN THE LAGGARD MODEL SOLUTIONS PEEL LIFT
OFF TO THE EAST AND FINALLY ALLOW THE FRONT TO SAG SOUTH OF THE
AREA. DRIER AIR QUICKLY MOVES INTO THE REGION...AS SKIES SEEM TO
RAPIDLY CLEAR. MUCH COOLER CONDITIONS/CALMER CONDITIONS WILL
INFILTRATE THE AREA BY FRIDAY NIGHT WITH ABUNDANT SUNSHINE THROUGH
MOST OF THE WEEKEND.
THE ONLY POSSIBLE CAVEAT TO THE FORECAST LIES IN THE FACE THAT THE
MID AND UPPER RIDGE NEVER MANAGES TO MAKE ITS WAY ALL THE WAY
TOWARD OUR REGION. WITH A RIDGE AXIS GENERALLY WEST OF THE
MISSISSIPPI RIVER...AND OFF SHORE TROUGHING BECOMING SEMI-
RESIDENT...THAT LEAVES OUR REGION IN PERSISTENT NORTHWESTERLY
FLOW. THIS WILL KEEP TEMPERATURES LARGELY IN CHECK THROUGH THE
WEEKEND...BUT ALSO LEAVES THE DOOR OPEN TO CONVECTIVE DEVELOPMENT
THAT MAY MANAGE TO SQUEAK OVER THE RIDGE AXIS. PREVIOUS VERSIONS
OF THE DGEX/ECMWF DID TRY TO EDGE A BIT OF THIS ACTIVITY TOWARD
THE AREA INTO LATE SUNDAY. THE CURRENT RUNS DO NOT FAVOR THIS
SOLUTION...SO THE FORECAST WAS KEPT DRY THROUGHOUT THE
WEEKEND...HOWEVER POPS WERE ALLOWED TO BE NON-ZERO BY SUNDAY TO
ACCOUNT FOR THE EXCEEDINGLY SMALL SHOT AT A SHOWER BY LATE IN THE
DAY. HOWEVER...ALL IN ALL...A DRY AND FAIRLY SUNNY WEEKEND LOOKS
TO BE IN STORE ON ALL CURRENT GUIDANCE WITH TEMPERATURES TRENDING
TOWARD NORMAL. FRIES
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THE MODELS AGREE THAT AN UPPER LEVEL RIDGE WILL BUILD OVER THE
CENTRAL PLAINS THROUGH THE LONG TERM. DESPITE THE CONSENSUS IN THE
OVERALL UPPER LEVEL PATTERN...THERE REMAINS INHERENT DIFFERENCES IN
SHORTWAVE TIMING AND PLACEMENT AS THE MODELS SUGGEST SEVERAL WAVES
WILL DROP THROUGH THE NORTHWEST FLOW OVER THE GREAT LAKES/OHIO
VALLEY. WITH THIS IN MIND...CONTINUED TO CARRY AT LEAST CHANCE
POPS THROUGH MUCH OF THE FORECAST PERIOD. DESPITE NORTHWEST
FLOW...BOTH TEMPERATURES AND DEWPOINTS SHOULD INCREASE THROUGH
MIDWEEK BRINGING A RETURN TO HOT AND HUMID CONDITIONS. FOR
NOW...MAINTAINED HIGHS JUST AT OR ABOVE SEASONAL AVERAGES.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
VCTS IN THE TAFS AS THIN LINE OF SHOWERS AND SCATTERED
THUNDERSTORMS ASSOCIATED WITH A COLD FRONT CROSS THE REGION. THE
COLD FRONT COMPLETES PASSAGE ACRS THE UPR OH VLY EARLY TONIGHT BUT
DEWPOINTS WILL BE SLOW TO FALL SO EXPECT SOME MVFR RESTRICTIONS
DUE TO FOG/HAZE IN EARLY MORNING HOURS.
.OUTLOOK.../FRIDAY THROUGH MONDAY/...
GENERAL VFR CONDITIONS THROUGH THE WEEKEND.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
122 PM EDT THU AUG 22 2013
.SYNOPSIS...
SHOWERS WILL BE LIKELY AS A COLD FRONT CROSSES THE AREA THROUGH
FRIDAY MORNING.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SHOWERS HAVE REALLY TAKEN THEIR TIME GETTING THEIR ACT TOGETHER.
SHOWERS HAVE FINALLY REDEVELOPED TO THE NORTH AND EAST OF
PITTSBURGH...WHILE LINE HAS GENERALLY HELD TOGETHER FROM THE
WESTERN LAKE ERIE SHORELINE AS IT MOVED INTO EASTERN OHIO AND THE
NORTHERN WEST VIRGINIA PANHANDLE. HAVE CHANGED POPS FOR TIMING OF
PRECIPITATION BASED ON RADAR TRENDS. THAT BEING SAID...AREAS SUCH
AS MERCER AND VENANGO COUNTY MAY REMAIN COMPLETELY DRY. THE LAST
FEW RUNS OF THE HRRR ATTEMPT TO HAVE ANOTHER LINE OF SHOWERS
DEVELOP ACROSS THE INTERSTATE 80 CORRIDOR WITH THE ACTUAL FRONTAL
PASSAGE LATE THIS AFTERNOON...BUT THE HRRR ALSO INDICATED THAT THE
CURRENT LINE OF SHOWERS WAS GOING TO HANG TOGETHER ALONG THE I-80
CORRIDOR WHICH DID NOT HAPPEN. HAVE STILL KEPT POPS GOING THROUGH
THE AFTERNOON HOURS IN ALL LOCATIONS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
SOUTHWARD IMPETUS FOR THE TRANSLATION OF THE FRONT SEEMS LIKE IT
SLOWLY FADES GOING INTO TONIGHT AND ESPECIALLY FRIDAY MORNING AS
THE MID-LEVEL FORCING ASSOCIATED WITH THE SYSTEM WILL HAVE ALREADY
SCREAMED EASTWARD INTO SOUTHERN QUEBEC AND MARITIME CANADA BY
FRIDAY MORNING. THIS LEAVES THE FRONT`S FORWARD PROGRESS TO SLOW
FAIRLY RAPIDLY AS IT STARTS TO LOSE DEFINITION THROUGH FRIDAY
MORNING. WITH THE FRONT HUNG UP...BOTH THE GFS AND NAM LIKE THE
IDEA OF RUNNING A SECONDARY VORT DOWN THE BOUNDARY LATE TONIGHT
INTO FRIDAY MORNING THAT MANAGES TO CLIP THE SOUTHERN AND
ESPECIALLY SOUTHEASTERN PORTIONS OF THE FORECAST AREA. DEEP LAYER
WESTERLY FLOW COMBINED WITH INSTABILITY AS WELL AS THE INTERACTION
WITH THE RIGHT ENTRANCE REGION OF THE UPPER JET THAT WILL BE
SITUATED OVER NORTHERN PENNSYLVANIA BY THAT TIME SHOULD ALLOW FOR
FAIRLY WIDESPREAD SHOWER DEVELOPMENT OVERNIGHT INTO FRIDAY MORNING
ACROSS THE SOUTHEASTERN ZONES. POPS WERE INCREASED SUBSTANTIALLY
IN THIS AREA TO ACCOUNT FOR BOTH LARGE SCALE AS WELL AS OROGRAPHIC
PRECIPITATION ENHANCEMENT.
BY FRIDAY AFTERNOON...EVEN THE LAGGARD MODEL SOLUTIONS PEEL LIFT
OFF TO THE EAST AND FINALLY ALLOW THE FRONT TO SAG SOUTH OF THE
AREA. DRIER AIR QUICKLY MOVES INTO THE REGION...AS SKIES SEEM TO
RAPIDLY CLEAR. MUCH COOLER CONDITIONS/CALMER CONDITIONS WILL
INFILTRATE THE AREA BY FRIDAY NIGHT WITH ABUNDANT SUNSHINE THROUGH
MOST OF THE WEEKEND.
THE ONLY POSSIBLE CAVEAT TO THE FORECAST LIES IN THE FACE THAT THE
MID AND UPPER RIDGE NEVER MANAGES TO MAKE ITS WAY ALL THE WAY
TOWARD OUR REGION. WITH A RIDGE AXIS GENERALLY WEST OF THE
MISSISSIPPI RIVER...AND OFF SHORE TROUGHING BECOMING SEMI-
RESIDENT...THAT LEAVES OUR REGION IN PERSISTENT NORTHWESTERLY
FLOW. THIS WILL KEEP TEMPERATURES LARGELY IN CHECK THROUGH THE
WEEKEND...BUT ALSO LEAVES THE DOOR OPEN TO CONVECTIVE DEVELOPMENT
THAT MAY MANAGE TO SQUEAK OVER THE RIDGE AXIS. PREVIOUS VERSIONS
OF THE DGEX/ECMWF DID TRY TO EDGE A BIT OF THIS ACTIVITY TOWARD
THE AREA INTO LATE SUNDAY. THE CURRENT RUNS DO NOT FAVOR THIS
SOLUTION...SO THE FORECAST WAS KEPT DRY THROUGHOUT THE
WEEKEND...HOWEVER POPS WERE ALLOWED TO BE NON-ZERO BY SUNDAY TO
ACCOUNT FOR THE EXCEEDINGLY SMALL SHOT AT A SHOWER BY LATE IN THE
DAY. HOWEVER...ALL IN ALL...A DRY AND FAIRLY SUNNY WEEKEND LOOKS
TO BE IN STORE ON ALL CURRENT GUIDANCE WITH TEMPERATURES TRENDING
TOWARD NORMAL. FRIES
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
THE MODELS AGREE THAT AN UPPER LEVEL RIDGE WILL BUILD OVER THE
CENTRAL PLAINS THROUGH THE LONG TERM. DESPITE THE CONSENSUS IN THE
OVERALL UPPER LEVEL PATTERN...THERE REMAINS INHERENT DIFFERENCES IN
SHORTWAVE TIMING AND PLACEMENT AS THE MODELS SUGGEST SEVERAL WAVES
WILL DROP THROUGH THE NORTHWEST FLOW OVER THE GREAT LAKES/OHIO
VALLEY. WITH THIS IN MIND...CONTINUED TO CARRY AT LEAST CHANCE
POPS THROUGH MUCH OF THE FORECAST PERIOD. DESPITE NORTHWEST
FLOW...BOTH TEMPERATURES AND DEWPOINTS SHOULD INCREASE THROUGH
MIDWEEK BRINGING A RETURN TO HOT AND HUMID CONDITIONS. FOR
NOW...MAINTAINED HIGHS JUST AT OR ABOVE SEASONAL AVERAGES.
&&
.AVIATION /17Z THURSDAY THROUGH MONDAY/...
WILL CONTINUE TO CARRY VCTS IN THE TAFS FOR THIS AFTERNOON AS
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A COLD FRONT CROSS THE
OHIO VALLEY. TRIED TO TIME THE THUNDER MENTION BASED OFF OF THE
MOST RECENT HI RES MODEL DATA...STARTING AT ZZV AND FKL AND MOVING
SOUTHEASTWARD. WESTERLY WIND FROM 5 TO 10KTS WITH HIGHER GUSTS
POSSIBLE IN THUNDERSTORMS. RESTRICTION POTENTIAL WL CONTINUE INTO
TONIGHT AS THE CDFNT COMPLETES PASSAGE ACRS THE UPR OH VLY.
.OUTLOOK.../FRIDAY THROUGH MONDAY/...
GENL IMPROVEMENT MAY BE ANTICIPATED FRIDAY AS HIGH PRES BLDS
THROUGH THE WEEKEND.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1222 PM CDT THU AUG 22 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 410 AM CDT THU AUG 22 2013
SHORT TERM TRENDS POINT TO SOME ISOLATED THUNDER LIFTING AS FAR
NORTH AS DECAYING FRONTAL BOUNDARY...WITHIN INSTABILITY AXIS AND
NORTHERN PERIPHERY OF COMPLEX OVER IOWA. WILL HAVE TO INCLUDE THIS
FOR MUCH OF THE MORNING HOURS ANYWAY.
THIS CONVECTION IS BEING FORCED BY SOME WEAK LAYERED FRONTOGENESIS.
THIS IS PROGGED BE THE HRRR AND MEMBER 1 AND 2 OF THE HOPWRF TO
GRADUALLY WEAKEN AND DROP FARTHER SOUTH AS DRIER AIR TRIES TO DROP
SOUTHWEST ERODING THE BOUNDARY. SHOULD SEE GRADUAL DRYING THEN INTO
THE AFTERNOON...AS SURFACE HIGH DROPS SOUTHEAST INTO TONIGHT.
CLOUDS SHOULD GIVE WAY TO CLEARING DURING THE DAY...AND CONTINUE
THIS TREND THROUGH THE NIGHT. TEMPERATURES COOL A BIT TO THE LOWER
AND MIDDLE 80S OVER MOST OF THE AREA TODAY. LOWS SHOULD COOL TO
AROUND 50 EAST AND AROUND 60 TO THE SOUTHWEST TONIGHT...AS DRIER AIR
MOVES ACROSS.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 410 AM CDT THU AUG 22 2013
THE MAIN WEATHER HEADLINE IN THE LONG TERM PORTION OF THE FORECAST
WILL BE BUILDING HEAT...AS MID LEVEL HEIGHTS GRADUALLY RISE IN
CONJUNCTION WITH THE EXTENSIVE RIDGE OVER THE CENTRAL CONUS. THE RETURN
OF THE HOT WEATHER WILL BE MET WITH THE ARRIVAL OF A WARM FRONT.
HAVE RETAINED 20-40 POPS FOR FRIDAY NIGHT INTO SATURDAY MORNING AS
THE AFOREMENTIONED FRONT BEGINS TO LIFT ACROSS THE AREA. ALTHOUGH
THE ORIENTATION OF THE 35-40KT PROGGED LLJ IS NOT IDEAL FOR
WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY...INDICATIONS ARE THAT
IT SHOULD BE ADEQUATE FROM CENTRAL MN INTO WEST CENTRAL WI TO
WARRANT LOW CHANCE POPS CENTERED BETWEEN 06Z AND 18Z SATURDAY.
AFTER THAT...OTHER THAN A FEW STRAY SHOWERS/TS NORTH OF INTERSTATE
94 CLOSER TO THE BOUNDARY...MOSTLY DRY CONDITIONS ARE EXPECTED
THROUGH MONDAY AS THE WARM FRONT LIFTS INTO NORTHERN MN. AS THIS
OCCURS...TEMPERATURES WILL MODERATE INTO THE LOW/MID 90S FOR
SUNDAY THROUGH TUESDAY AS DEWPOINTS CREEP TO AROUND 70 DEGREES.
THIS COULD MEAN A PROLONGED PERIOD WITH A HEAT ADVISORY...WITH MAX
HEAT INDICES NEARING 100 DEGREES AND OVERNIGHT LOW TEMPS REMAINING
ELEVATED IN THE LOW/MID 70S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1209 PM CDT THU AUG 22 2013
FEW CONCERNS DURING THE PERIOD AS HIGH PRESSURE OVER ND WORKS
SLOWLY SOUTHEASTWARD ACROSS MN/WI. BIGGEST PROBLEM IS THE WIND
DIRECTION THIS AFTERNOON. THE WIND WILL BE MAINLY FROM THE NE
(040-070) AT NEAR 10 KNOTS... BUT SOME EXCURIONS TO NORTH AND EAST
ARE POSSIBLE. GUSTS UP TO 20 KNOTS AS WELL THIS AFTERNOON.
KMSP...VFR THROUGH THE PD. MAIN CONCERN IS THE WIND DIRECTION AND
SPEED AS DESCRIBED ABOVE. RECENT AIRCRAFT DATA AT MSP INDICATED
NEAR 20 KNOT WINDS ABOUT 1200 FEET AGL. MIXING IS ALLOWING SOME OF
THIS TO REACH THE GROUND IN THE FORM OF GUSTS. LIGHT NE WIND THIS
EVENING BECOMING SE BY DAYBREAK AND THEN INCREASING TO AROUND 10
KNOTS BY LATE FRIDAY MORNING.
/OUTLOOK FOR KMSP/
FRI NGT...VFR. CHC SHRA/TSRA. WINDS SE 10 KTS.
SAT...VFR CHC SHRA/TSRA EARLY. WINDS SOUTH 18 KTS G 24 KTS.
SUN...VFR. SW WIND 15 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...DWE
LONG TERM...LS
AVIATION...RAH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
311 PM EDT THU AUG 22 2013
.SYNOPSIS...
RIDGE OF HIGH PRESSURE OFFSHORE WILL SLOWLY GIVE WAY TO A COLD FRONT
APPROACHING FROM THE NORTHWEST ON FRIDAY. THIS FRONT WILL CROSS THE AREA
BY EARLY SATURDAY. THE COLD FRONT WILL USHER IN COOLER AND DRIER
CONDITIONS FOR THE WEEKEND INTO EARLY NEXT WEEK. A WARMING TREND WILL
TAKE PLACE MID WEEK NEXT WEEK AS HIGH PRESSURE SHIFTS OFFSHORE.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 3 PM THURSDAY...WATER VAPOR IMAGERY IS SHOWING THE SHORTWAVE
CONTINUING TO MOVE ACROSS THE MID-ATLANTIC AND EASTERN CAROLINAS.
LINES OF CONVECTION HAVE FORMED AND ARE MOVING TOWARD THE
EAST-SOUTHEAST. AT THIS TIME THE CONVECTION IS STAYING BELOW SEVERE
LIMITS AND IS MOVING AROUND 10 KNOTS. WITH THE LINEAR CONFIGURATION
THAT HAS DEVELOPED IT APPEARS THAT ANY THREAT FOR FLOODING IS SMALL.
THE
LATEST HRRR IS SHOWING THE CONVECTION CONTINUING TO THE COAST AND
DYING AS IT MOVES OUT OVER THE WATERS. EXPECT THE CONVECTION TO
CONTINUE THROUGH THE EARLY EVENING HOURS.
OVERNIGHT MINIMUM TEMPERATURES ARE EXPECTED TO FALL BACK INTO THE
LOWER 70S INLAND AND MID 70S AT THE BEACHES.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
AS OF 300 PM THURSDAY...CONCERN THROUGH THE SHORT TERM REVOLVES
AROUND A COLD FRONT WHICH WILL DROP THROUGH THE AREA LATE FRIDAY
NIGHT INTO SATURDAY...AND ITS RELATED CONVECTION POTENTIAL.
FRIDAY WILL BEGIN RATHER NICE...AND WILL BE A WARM DAY. SUBSIDENCE
BEHIND A DEPARTING SHORTWAVE WITH SUBTLE HEIGHT INCREASES ALOFT WILL
CREATE SUBSTANTIAL EARLY SUNSHINE. THIS WILL DRIVE TEMPS UP TO
AROUND 90 AWAY FROM THE BEACHES. THESE WARM TEMPS COMBINED LOW-LEVEL
SW FLOW AROUND RETREATING HIGH PRESSURE OFFSHORE WILL CREATE
SIGNIFICANT INSTABILITY...WITH SBCAPE AND MLCAPE APPROACHING 2000
J/KG FRIDAY AFTN. IN ADDITION...LOW-LEVEL LAPSE RATES FROM SURFACE
TO 850MB WILL BE QUITE STEEP...AND DCAPE REACHES 600-1000 J/KG
FRIDAY EVE. THESE ALL SUGGEST TSTM POTENTIAL. HOWEVER...BULK SHEAR
IS QUITE LOW...AND PWATS ARE ONLY ABOUT 1.8 INCHES...LIMITING SEVERE
POTENTIAL. SPC HAS PLACED THE AREA IN A "SEE TEXT" FOR THE SWODY2 AS
THE FRONT APPROACHES INTO THIS UNSTABLE ENVIRONMENT. HOWEVER...FEEL
SEVERE POTENTIAL IS QUITE LOW HERE SINCE THE FRONT WILL NOT CROSS
UNTIL VERY LATE FRIDAY NIGHT...AND SOUNDINGS ARE NOT SO SATURATED
THAT WET-MICROBURSTS ARE FAVORABLE. STILL...WITH THE STEEP LOW-LEVEL
LAPSE RATES AND HIGH INSTABILITY...AN ISOLATED STRONG WIND GUST
CANNOT BE RULED OUT IN ANY AFTN PULSE STORM OR NIGHTTIME CONVECTION
BEFORE THE SURFACE LAYER STABILIZES. THIS MEANS THE MOST LIKELY
PLACE FOR A STRONGER WIND GUST WOULD BE ALONG THE SEA BREEZE
CONVECTION...IF ANY...FRIDAY AFTN...OR ALONG THE FAR NORTHERN TIER
AS THE FRONT APPROACHES FRIDAY NIGHT. WILL NOT MENTION SEVERE IN
GRIDS OR ZONE FORECAST PRODUCT.
FROPA WILL OCCUR OVERNIGHT FRIDAY...AND BY SATURDAY MORNING WILL
HAVE CLEARED THE CWA. COOL HIGH PRESSURE BUILDS IN BEHIND THIS
FRONT...BUT AS NE WINDS DEVELOP...MOISTURE ADVECTION WILL COMMENCE
OFF THE OCEAN...AND IT WILL TAKE MUCH OF SATURDAY BEFORE DRYING OF
THE COLUMN BELOW 700MB OCCURS. THIS CREATES SHOWERS AND CLOUDS MOST
OF THE DAY...WITH CLEARING OCCURRING ONLY BY SATURDAY NIGHT FROM
NORTH TO SOUTH.
TEMPS FRIDAY NIGHT WILL BE TRICKY DUE TO TIMING OF THE FRONT...BUT
IT APPEARS NEGATIVE 850MB THERMAL ADVECTION HOLDS OFF UNTIL
SATURDAY...SO FRIDAY NIGHT TEMPS WILL BE ABOVE 70 CWA-WIDE. HIGHS
SATURDAY WILL REACH INTO THE LOW 80S...AND HAVE UNDERCUT MOS NUMBERS
A BIT. LOWS SATURDAY NIGHT WILL FALL WELL INTO THE 60S AS A MUCH
DRIER AIRMASS MOVES INTO THE REGION.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 300 PM THURSDAY...MID LEVEL PATTERN WILL BE DOMINATED BY
MASSIVE RIDGING CENTER ACROSS KANSAS WITH AN EASTWARD
EXTENSION/AXIS ACROSS THE CAROLINAS. AT THE SURFACE...HIGH
PRESSURE AXIS WILL INITIALLY BE OVER THE MID ATLANTIC AND IN TIME
WILL BECOME ELONGATED EAST/WEST ACROSS THE SOUTHEAST. THE EASTERN
EDGE OF THE RIDGE WILL WEAKEN AS SEVERAL SHORTWAVES RIDE THE
PERIPHERY AND DIP SOUTHWARD. THERE WILL ALMOST CERTAINLY BE
SEVERAL MESOSCALE CONVECTIVE SYSTEMS WITH THIS PATTERN AND ONE IF
NOT MORE MAY BE A FACTOR LATE IN THE PERIOD BUT ALL BUT IMPOSSIBLE
TO PINPOINT THIS FAR OUT IN TIME. THUS...THE FORECAST REMAINS DRY
THROUGHOUT.
THE ONLY INTERESTING NOTE REGARDING TEMPERATURES IS THE MEX GUIDANCE
HAS DECREASED SOMEWHAT WITH 61 IN WILMINGTON FOR MONDAY MORNING.
THIS SEEMS LIKE A REASONABLE TREND...COOLER AS CLIMATOLOGY BECOMES
LESS OF A FACTOR WITH TIME AND GEFS 850MB TEMPERATURES ARE 2-3
STANDARD DEVIATIONS BELOW NORMAL.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
AS OF 18Z...TERMINALS ARE CURRENTLY VFR AND VFR IS EXPECTED TO
CONTINUE THROUGH THE AFTERNOON AND EVENING OUTSIDE OF ANY
PRECIPITATION. AN UPPER IMPULSE IS PROGGED BY MODELS TO MOVE
ACROSS THE TERMINALS. SHOWERS AND ISOLATED THUNDERSTORMS ARE
EXPECTED WITH HIGHEST CONFIDENCE OF VCTS/TEMPO MVFR CONDITIONS
ALONG THE SEA BREEZE AT KMYR/KCRE/KILM AND LOWEST CONFIDENCE AT
KFLO/KLBT. SHOWERS AND THUNDERSTORMS SHOULD END THIS EVENING WITH
LOSS OF HEATING. IN THE PRE-DAWN HOURS PATCHY FOG WILL DEVELOP
WITH THE HIGHEST CONFIDENCE OF SUB- VFR CONDITIONS AT KFLO/KLBT.
VFR SHOULD DEVELOP AN HOUR OR SO AFTER SUNRISE WITH VFR EXPECTED
THROUGH THE MORNING HOURS AT ALL TERMINALS.
EXTENDED OUTLOOK...SCATTERED SHOWERS AND T-STORMS FRIDAY AFTERNOON
THROUGH SATURDAY MORNING ASSOCIATED WITH A COLD FRONT. VFR SUNDAY
THROUGH TUESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM THURSDAY...HIGH PRESSURE CONTINUES TO RIDGE BACK
ACROSS THE COASTAL WATERS. THE WINDS WILL CONTINUE TO BE AT OR
LESS THAN 10 KNOTS FROM THE SOUTHWEST AND THIS WILL CONTINUE THE
BENIGN CONDITIONS WITH SEAS OF 2 TO 3 FEET. WITH A WEST-NORTHWEST
FLOW...WE MAY SEE A FEW THUNDERSTORMS TRYING TO WORK THEIR WAY
BACK OVER THE WATERS BUT THEY SHOULD ONLY BE AT OR NEAR THE
COASTLINE.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 PM THURSDAY...PRE-FRONTAL AIRMASS FRIDAY WILL TRANSITION
TO POST-FRONTAL SATURDAY THANKS TO A COLD FRONT WHICH WILL DROP
SOUTHWARD ACROSS THE WATERS OVERNIGHT FRIDAY. SW WINDS WILL BE 10-15
KTS MOST OF FRIDAY...BEFORE RAPIDLY SHIFTING TO THE NORTH BY
SATURDAY MORNING AT LESS THAN 10 KTS...WITH A NE SURGE DEVELOPING AT
THE END OF THE PERIOD...INCREASING WINDS TO 15 KTS OR MORE. WAVES
WILL BE NEARLY ENTIRELY FORMED BY THE WIND-WAVE GROUP...WITH 2-3 FT
SEAS FRIDAY CREATED BY SW WIND CHOP...THEN BECOMING 2-4 FT LATE
SATURDAY THANKS TO THE DEVELOPING NE WIND WAVE.
LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 300 PM THURSDAY...A FAIRLY BRISK NORTHEASTERLY FLOW WILL
PREVAIL FOR MOST OF THE DAY SUNDAY WITH SPEEDS 10-15 KNOTS AND
PROBABLY HOVERING MORE TOWARD THE HIGHER END OF THE RANGE. AS HIGH
PRESSURE WEAKENS AND MOVES TO THE SOUTH...WINDS WILL DIMINISH TO
TEN KNOTS OR LESS BY MONDAY AFTERNOON. A FURTHER SHIFTING OF THE
HIGH TO BASICALLY OVERHEAD WILL LEAD TO WINDS BASICALLY LIGHT AND
VARIABLE TUESDAY. OVERALL SEAS ARE NEVER REALLY IMPRESSIVE WITH
3-4 FEET SUNDAY TRENDING DOWN TO AROUND TWO FEET TUESDAY.
&&
.TIDES/COASTAL FLOODING...
AS OF 125 PM THURSDAY...THE LATEST TIDE FORECAST FOR THE CAPE FEAR
RIVER IN WILMINGTON IS SHOWING THE RIVER REACHING LEVELS OF MINOR
COASTAL FLOODING. THE PEAK OF THE TIDE IS FORECASTED TO REACH 5.5
FEET BETWEEN 11 PM AND MIDNIGHT. THUS A COASTAL FLOOD ADVISORY FOR THE
CAPE FEAR RIVER AROUND DOWNTOWN WILMINGTON HAS BEEN ISSUED BETWEEN
10 PM AND 1 AM.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...COASTAL FLOOD ADVISORY FROM 10 PM THIS EVENING TO 1 AM EDT
FRIDAY FOR NCZ107.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...DRH
SHORT TERM...JDW
LONG TERM...SHK
AVIATION...MRR/DRH
MARINE...JDW/SHK/DRH
TIDES/COASTAL FLOODING...DRH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
147 PM EDT THU AUG 22 2013
.SYNOPSIS...
A RIDGE OF HIGH PRESSURE WILL PERSIST OVER THE WESTERN ATLANTIC
OCEAN TODAY. A COLD FRONT WILL APPROACH FRIDAY AND WILL THEN
CROSS THE AREA EARLY SATURDAY USHERING IN COOLER AND DRIER
CONDITIONS FOR THE WEEKEND INTO EARLY NEXT WEEK. A WARMING TREND
WILL TAKE PLACE MID WEEK NEXT WEEK AS HIGH PRESSURE SHIFTS OFF
SHORE.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 145 PM THURSDAY...WATER VAPOR IMAGERY IS SHOWING THE
SHORTWAVE MOVING INTO THE EASTERN CAROLINAS. THE RADAR HAS BEGUN
DETECTING THE CONVECTION DEVELOPING OVER THE PEE DEE AREA AND
INLAND PORTIONS OF SOUTHEAST NORTH CAROLINA. WITH DENSE CLOUDS
ALONG THE COAST MOVING OFF THE COAST THE AFTERNOON HEATING WILL
COMMENCE IN THE AREA AND SCATTERED CONVECTION IS EXPECTED TO
DEVELOP AS DEPICTED IN THE 16 UTC RUN OF THE HRRR MESOSCALE MODEL.
AS THE SHORTWAVE IS FORECASTED TO MOVE OF THE COAST BETWEEN 21 AND
00 UTC EXPECT THE COVERAGE OF CONVECTION TO TREND BACK A BIT BY
THIS EVENING THEN FINALLY CEASE AFTER SUNSET.
OVERNIGHT MINIMUM TEMPERATURES ARE EXPECTED TO FALL BACK INTO THE
LOWER 70S INLAND AND MID 70S AT THE BEACHES.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...EXITING SHORTWAVE WILL PRODUCE SOME
SUBSIDENCE AND DRYING THROUGH THE MID LEVELS ON FRI. THE LOW TO
MID LEVEL FLOW BEHIND SHORTWAVE WILL HAVE A STRONG WESTERLY
COMPONENT. THEREFORE BEST CONVERGENCE WILL REMAIN CLOSER TO THE
COAST AS ON SHORE FLOW DEVELOPS IN SEA BREEZE. THIS WILL PRODUCE
BEST CHC OF SHWRS/TSTMS CLOSER TO THE COAST...ESPECIALLY FURTHER
SOUTH. THE DOWNSLOPE WESTERLY FLOW WILL ALSO HELP TO LIMIT OVERALL
ACTIVITY ON FRI. LOOKS LIKE A BREAK IN THE SOMEWHAT LIMITED
ACTIVITY WILL TAKE PLACE THROUGH THE EVENING BEFORE A COLD FRONT
ACTUALLY PUSHES SOUTHEAST INTO THE AREA. THE DEEPEST LAYER
MOISTURE LOOKS LIKE IT WILL BE OVERNIGHT FRI BUT THE POTENTIAL FOR
TSTMS DOES NOT LOOK TOO IMPRESSIVE AS THE FRONT COMES THROUGH AT
A NON-DIURNALLY FAVORED TIME OF DAY. THE H5 TROUGH WILL PUSH
FRONT SOUTH SAT MORNING...BUT LATEST GFS SHOWS INCREASED POTENTIAL
FOR SHWRS ON SAT WITH BEST CONVERGENCE FROM THE TIP OF CAPE FEAR
SOUTH...WHERE BEST CONVERGENCE AND RESIDUAL MOISTURE WILL BE.
DEEP N-NW FLOW DEVELOPING BEHIND FRONT AS MID TO UPPER TROUGH
AXIS SHIFTS FARTHER OFF THE COAST AND HIGH PRESSURE BUILDS IN
THROUGH SATURDAY. PCP WATER VALUES WILL DROP FROM CLOSE TO 2
INCHES AHEAD OF FRONT TO LESS THAN AN INCH BY END OF PERIOD OR
EARLY SUNDAY. THEREFORE EXPECT CLEARING THROUGH SAT NIGHT.
RESIDUAL LOW LEVEL MOISTURE FROM PCP MAY PRODUCE FOG ACROSS THE
AREA SAT NIGHT.
TEMPS WILL RUN SLIGHTLY ABOVE NORMAL IN A WARMER AIR MASS ON FRI
AIDED BY WESTERLY FLOW. CLOUDS AND SHOWERS ASSOCIATED WITH FRONT
WILL KEEP TEMPS ON THE HIGH SIDE FRI NIGHT BUT TEMPS WILL RUN
CLOSER TO NORMAL BY SAT INTO SAT NIGHT AS DRIER AIR MAKES ITS WAY
IN.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...DRIER AIR WILL CONTINUE TO MAKE ITS WAY
IN DEEPER NORTHERLY FLOW AS HIGH PRESSURE NOSES IN FROM THE NORTH
AS IT GRADUALLY SHIFTS EAST THROUGH MID WEEK. OVERALL EXPECT
PLENTY OF SUNSHINE WITH TEMPS MODERATING FROM BELOW NORMAL SUNDAY
INTO MONDAY TO ABOVE NORMAL BY WED AS MID TO UPPER RIDGE BUILDS
EAST INTO THE CAROLINAS PRODUCING H5 HEIGHT RISES. GRADIENT WINDS
WILL WEAKEN AS HIGH SHIFTS SOUTH AND EAST WITH MAINLY DIURNAL
SHIFTS DUE TO SEA BREEZE/LAND BREEZE. 850 TEMPS WILL BOTTOM OUT
AROUND 13C IN COOLER AIR ADVECTING IN BEHIND FRONT THROUGH SUNDAY
AND WILL RISE UP TO 18C BY TUES INTO WED. THE DIURNAL SWINGS IN
TEMPS WILL BE FAIRLY LARGE WITH DRY AIR IN PLACE AND DEWPOINT
TEMPS IN THE LOWER END OF 60S AND POSSIBLY BELOW OVER NORTHERN
TIER ZONES LATE SUNDAY INTO EARLY TUES.
&&
.AVIATION /18Z THURSDAY THROUGH MONDAY/...
AS OF 18Z...TERMINALS ARE CURRENTLY VFR AND VFR IS EXPECTED TO
CONTINUE THROUGH THE AFTERNOON AND EVENING OUTSIDE OF ANY
PRECIPITATION. AN UPPER IMPULSE IS PROGGED BY MODELS TO MOVE
ACROSS THE TERMINALS. SHOWERS AND ISOLATED THUNDERSTORMS ARE
EXPECTED WITH HIGHEST CONFIDENCE OF VCTS/TEMPO MVFR CONDITIONS
ALONG THE SEA BREEZE AT KMYR/KCRE/KILM AND LOWEST CONFIDENCE AT
KFLO/KLBT. SHOWERS AND THUNDERSTORMS SHOULD END THIS EVENING WITH
LOSS OF HEATING. IN THE PRE-DAWN HOURS PATCHY FOG WILL DEVELOP
WITH THE HIGHEST CONFIDENCE OF SUB- VFR CONDITIONS AT KFLO/KLBT.
VFR SHOULD DEVELOP AN HOUR OR SO AFTER SUNRISE WITH VFR EXPECTED
THROUGH THE MORNING HOURS AT ALL TERMINALS.
EXTENDED OUTLOOK...SCATTERED SHOWERS AND T-STORMS FRIDAY AFTERNOON
THROUGH SATURDAY MORNING ASSOCIATED WITH A COLD FRONT. VFR SUNDAY
THROUGH TUESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 145 PM THURSDAY...HIGH PRESSURE CONTINUES TO RIDGE BACK
ACROSS THE COASTAL WATERS. THE WINDS WILL CONTINUE TO BE AT OR
LESS THAN 10 KNOTS FROM THE SOUTHWEST AND THIS WILL CONTINUE THE
BENIGN CONDITIONS WITH SEAS OF 2 TO 3 FEET. WITH A WEST-NORTHWEST
FLOW...WE MAY SEE A FEW THUNDERSTORMS TRYING TO WORK THEIR WAY
BACK OVER THE WATERS BUT THEY SHOULD ONLY BE AT OR NEAR THE
COASTLINE.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...WEST TO SOUTHWEST FLOW WILL VEER AROUND TO
THE NORTH TO NORTHEAST AND INCREASE SLIGHTLY AHEAD OF COLD FRONT
SLATED TO MOVE INTO AND THROUGH THE WATERS SATURDAY MORNING.
EXPECT WINDS 10-15 KTS THROUGH MUCH OF FRIDAY AHEAD OF FRONT. THE
WINDS WILL SHIFT AROUND TO THE NORTH TO NORTHEAST THROUGH SATURDAY
AND WILL CONTINUE TO VEER AROUND SLIGHTLY MORE AND WILL INCREASE
AS COOL AIR ADVECTS OVER WARMER WATERS PRODUCING A WELL MIXED
MARINE LAYER AND GUSTY NORTHEAST WINDS. WINDS MAY INCREASE UP TO A
SOLID 15 KTS OVERNIGHT SATURDAY AS CAA INCREASES. SEAS WILL INCREASE
SLIGHTLY UP AROUND 3 FT AHEAD OF COLD FRONT BUT BIGGER INCREASE UP
TO AROUND 4 FT WILL COME IN NORTHEAST SURGE BEHIND FRONT THROUGH
SATURDAY NIGHT INTO THE LATTER HALF OF THE WEEKEND.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 300 AM THURSDAY...NORTHEAST WINDS UP TO 15 KTS MAY INCREASE
CLOSER TO 20 KTS IN OUTER WATERS AS COLD AIR ADVECTS OVER WATERS
AS HIGH PRESSURE BUILDS IN BEHIND COLD FRONT. THIS SURGE WILL
PRODUCE A RISE IN SEAS UP TO 4 FT AND MAYBE A LITTLE HIGHER IN THE
OUTER WATERS SUNDAY THROUGH SUNDAY NIGHT. THE WINDS WILL LIGHTEN
AS HIGH PRESSURE SHIFTS SOUTH AND AIR MASS BEGINS TO MODIFY
THROUGH LATE MONDAY. OVERALL SEAS WILL BE 2 TO 4 FT MOST WATERS.
&&
.TIDES/COASTAL FLOODING...
AS OF 125 PM THURSDAY...THE LATEST TIDE FORECAST FOR THE CAPE FEAR
RIVER IN WILMINGTON IS SHOWING THE RIVER REACHING LEVELS OF MINOR
COASTAL FLOODING. THE PEAK OF THE TIDE IS FORECASTED TO REACH 5.5
FEET BETWEEN 11 PM AND MIDNIGHT. THUS A COASTAL FLOOD ADVISORY FOR THE
CAPE FEAR RIVER AROUND DOWNTOWN WILMINGTON HAS BEEN ISSUED BETWEEN
10 PM AND 1 AM.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...COASTAL FLOOD ADVISORY FROM 10 PM THIS EVENING TO 1 AM EDT
FRIDAY FOR NCZ107.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...DRH
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...MRR
MARINE...
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
152 PM EDT THU AUG 22 2013
.SYNOPSIS...
MID/UPPER LEVEL DISTURBANCE CROSSES TODAY. COLD FRONT
TONIGHT AND FRIDAY. HIGH PRESSURE FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
11 AM UPDATE. CONCERNS FOR MORE ORGANIZED CONVECTION THIS AFTERNOON
AND TONIGHT WITH PW.S AROUND 2 INCHES...HAS PROMPTED A FLASH FLOOD
WATCH FOR MUCH OF WEST VIRGINIA FROM 2 PM THIS AFTERNOON THRU 11 AM
FRIDAY. THE AREAS OF CONCERN ARE GENERALLY THOSE AREAS THAT RECEIVED
POCKETS OF HEAVY RAIN AND WATER ISSUES LAST EVENING. SEE BELOW FOR
AREA SPECIFICS.
PREVIOUS DISCUSSION BELOW...
UPR LOW SHOULD BE E OF AREA BY MORNING. WILL KEEP LOW POPS THRU
MORNING TO ACCOUNT FOR ANY POP UP SHRA WITH LIFT WITH UPR LVL SYS.
ATTENTION THEN TURNS UPSTREAM FOR POTENTIALLY ACTIVE AFTN ACROSS THE
AREA. MDLS HAVE BEEN FAIRLY CONSISTENT IN PAST 24 HRS ON BRINGING
DOWN A DISTURBANCE AND PREFRONTAL LINE OF CONVECTION LATER TDY. THIS
SHOWS UP NICELY IN THE H7-H5 LYR OMEGA FIELDS ALONG WITH MID LVL
PVA. THE QUESTION IS HOW MUCH INSTABILITY CAN BE REALIZED WITH
POTENTIAL FOR DEBRIS CLDS TO WORK IN HERE THIS MORNING. WILL HEDGE
THAT BULK OF DEBRIS CLDS WILL STAY W OF AREA...MORE INTO KY...AND
DISSIPATE AS RUC SUGGESTS. WILL LEAN ON FASTER NAM/WRF MDLS FOR
TIMING THIS AFTN...ALTHOUGH EVEN SLOWER GFS NOT TOO FAR BEHIND. WILL
BRING IN LKLY POPS INTO SE OH 17 TO 19Z AND LOWLANDS/NE KY 19 TO
21Z...INTO MTNS/SW VA 22 TO 00Z. THERE IS SOME CONCERN THIS TRIES TO
SLOW DOWN A BIT ACROSS S ZONES...IE SW VA...THIS EVE.
OVERALL...THOUGH...THIS SHOULD MOVE RIGHT ALONG WITH STORM MOTIONS
15 TO 20 KTS.
AS FOR WATER CONCERNS...THERE WERE SOME PLACES THAT
GOT A GOOD HIT YESTERDAY...MAINLY ALONG I64 CORRIDOR FROM HTS TO
CRW. PWATS SURGE RIGHT BACK UP NEAR 2 INCHES WITH THIS FEATURE
WHICH MEANS DOWNPOURS A GOOD BET. ELECTED TO CODE UP A HVY RA
MENTION IN WX GRIDS WITH CONVECTION. WITH DECENT STORM MOTIONS AND
MOVEMENT LESS CONDUCIVE TO TRAINING...WILL FORGO A WATCH ATTM BUT
PUT A MENTION IN HWO FOR POSSIBLE STREET FLOODING AND LOW LYING
AREA CONCERNS.
ASSUMING MDLS ARE CORRECT...SHOULD SEE A LULL THIS EVE BEFORE SFC
FRONT APPROACHES. MDLS SEEM TO PLACE FRONT ALONG OH RVR BY END OF
NEAR TERM. UNCLEAR ON HOW ACTIVE ACTUAL BOUNDARY WILL BE GIVEN
NIGHT TIME HRS. HOWEVER...WITH DECENT LIFT SHOWN...WILL CODE UP
SOME HIGH CHC POPS OVERNIGHT AND KEEP A SMALL THUNDER THREAT IN.
CANT RULE OUT A FEW SVR CELLS THIS AFTN...MAINLY WIND. BUT
AGAIN...DOWNPOURS BIGGEST ISSUE.
FOR TEMPS...HEDGED TOWARD LAMP GUIDANCE ONCE AGAIN GIVEN ITS
RECENT PERFORMANCE. THIS RESULTED IN MINOR TWEAKS HERE AND THERE
FROM PREV FCST. GENERALLY LOW TO MID 80S ONCE AGAIN. LEANED ON
WARM SIDE TONIGHT GIVEN ABUNDANCE OF MOISTURE ABOUT THE AREA AND
SHRA THREAT.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
MODELS STILL HAVE SOME TIMING DIFFERENCES ON FRIDAY WITH THE COLD
FRONT AND ASSOCIATED MOISTURE. NAM CONTINUES TO BE THE SLOWEST WHILE
THE CANADIAN IS THE FASTEST. GFS AND ECMWF LIE IN THE MIDDLE. WITH
NO OBVIOUS REASON WHY ONE MODEL WOULD BE BETTER THAN THE
OTHER...WILL CONTINUE TO RUN A MIDDLE OF THE ROAD SOLUTION.
HIGH PRESSURE THEN TAKES OVER FOR THE WEEKEND...PROVIDING DRY
WEATHER AND LOW HUMIDITY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
UPPER RIDGE BUILDING OVER THE SOUTHERN PLAINS THROUGH THE LONG TERM
FORECAST. THE CENTER OF THE 500MB HIGH GENERALLY DRIFTS AROUND OVER
KS/OK/MO...WHICH KEEPS OUR REGION IN NW FLOW ALOFT...WITH SEVERAL
RIPPLES DROPPING THROUGH. TIMING/LOCATION OF EACH INDIVIDUAL WAVE
VARY BETWEEN GFS/ECMWF. SOME LOW LEVEL MOISTURE SHOULD BE AVAILABLE
WITH SE SURFACE FLOW...BUT JUST HOW MUCH WILL DEPEND ON WHERE
SURFACE HIGH IS. IF IT STAYS OVER THE SE STATES...WE WOULD GET AT
LEAST SOME MOISTURE ADVECTION FROM THE GULF...WHILE IF IT THE
SURFACE HIGH DRIFTS FARTHER WEST AS THE ECMWF HINTS...THAT RICHER
MOISTURE FLOW COULD GET CUT OF. DUE TO THIS UNCERTAINTY...STAYED
PRETTY CLOSE TO WPC GUIDANCE. WITH 500 HEIGHTS OVER 590DAM...LOOKS
LIKE A WARM STRETCH...WITH LOWLAND HIGHS IN THE UPPER 80S AND EVEN
SOME 90S NEXT WEEK. COULD ACTUALLY BE WARMER IF WE DO NOT HAVE THE
GOOD MOISTURE FLOW...AS THE DRIER AIR WOULD BE EASIER TO WARM.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
18Z THURSDAY THRU 18Z FRIDAY...
CONVECTIVE COMPLEXES EXPECTED TO DROP SOUTHEAST ACROSS THE AREA THRU
06Z...WELL AHEAD OF THE COLD FRONT WHICH IS EXPECTED TO ENTER OUR
SOUTHEAST OHIO ZONES AROUND 09Z...THEN PROGRESS ACROSS THE AREA
DURING FRIDAY. MOST OF THE ACTION WILL BE AHEAD OF THE FRONT THIS
AFTERNOON AND EARLY TONIGHT...WITH ADDITIONAL LIGHTER CONVECTION
WITH THE FRONT ITSELF.
GENERALLY VFR SCT-BKN 3500-4000 FT AGL THRU 02Z OUTSIDE OF
CONVECTION. MVFR TO LOCALLY IFR IN STRONGER CONVECTION...ESPECIALLY
IN THE 22Z TO 03Z TIME PERIOD. THEREAFTER...EXPECT CONVECTION TO
DIMINISH IN COVERAGE AND INTENSITY...BUT REPLACED BY GENERAL MVFR
CEILINGS EXCEPT IFR IN THE HIGHER MOUNTAINS. DEPENDING ON CLOUD
COVER OVERNIGHT...FOG MAY BE AN ISSUE. EXPECT ENOUGH OF A BREAK FOR
IFR FOG CONDITIONS 06Z TO 12Z.
AFTER 12Z...LINGERING LIGHT SHOWERS ENDING AND CEILINGS IMPROVING TO
VFR FROM THE NORTHWEST BY END OF PERIOD.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY...
FORECAST CONFIDENCE: LOW TO MEDIUM.
ALTERNATE SCENARIOS: TIMING OF CONVECTION THRU THE PERIOD DEPENDS
HIGHLY ON MESOSCALE COMPLEXES COMPLEXES. FOG WILL VARY DEPENDING ON
CLOUD COVER.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
CRW CONSISTENCY H H H H H H H H H M M L
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H M H H H H H H H H H M
EKN CONSISTENCY M H H H H H H H H L H H
PKB CONSISTENCY H H H H H H H H H H M M
CKB CONSISTENCY H H H H H H H H H M M M
AFTER 18Z FRIDAY...
AREAS OF IFR IN DENSE FOG/LOW STRATUS MOST MORNINGS THIS
WEEK...ESPECIALLY ALONG THE RIVERS. IFR IN SHOWERS AND THUNDERSTORMS
FRIDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR WVZ006>011-
013>020-026>032-038>040-047.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/JMV/30
NEAR TERM...JMV/30
SHORT TERM...RPY
LONG TERM...MZ
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1033 AM PDT Thu Aug 22 2013
.SYNOPSIS...
Warm and dry weather will continue through Thursday. Chances for
showers and thunderstorms will increase Thursday night into Friday
as a moist upper level disturbance tracks across eastern
Washington and the Idaho Panhandle. Warm weather with the threat
for thunderstorms will persist through the weekend into early next
week as a moist southwest flow pattern remains over the region.
&&
.DISCUSSION...
Upgraded fire weather products to red flag warnings with an update
earlier this morning and added sprinkles near the Lewiston
vicinity and some points northeast based on Radar and HRRR model
runs this morning. No other significant changes made as as the
most impressive portion of the forecast remains overnight and into
Friday as an upper level low pushes thunderstorms from south to
north through the forecast area in varying intensity. /Pelatti
&&
.AVIATION...
18Z TAFS: The only possible MVFR condition will be from wildfire
smoke around KEAT, but the threat is not significant enough at
this time to include in the TAF forecast. Mid to high level clouds
will continue to stream through the next 12 hrs or so. After 6Z
thunderstorms will start to make progress in the far south and
continue to move north and impact the aviation area into Friday.
/Pelatti
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 90 63 81 58 83 60 / 0 30 50 10 20 20
Coeur d`Alene 89 57 79 54 83 57 / 0 30 50 10 20 20
Pullman 90 57 80 51 83 52 / 10 40 50 10 20 20
Lewiston 95 66 87 61 90 62 / 10 30 50 10 10 20
Colville 92 55 85 52 86 54 / 0 20 50 20 20 10
Sandpoint 87 53 77 48 83 51 / 0 20 50 30 20 20
Kellogg 88 56 77 54 84 56 / 10 30 50 20 20 20
Moses Lake 93 65 87 58 84 59 / 0 30 40 10 20 10
Wenatchee 91 65 86 62 83 63 / 0 20 30 0 20 10
Omak 92 61 87 58 85 60 / 0 20 40 10 20 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Red Flag Warning from 11 PM this evening to 2 PM PDT Friday for
Northern and Central Idaho Panhandle (Zone 101).
WA...Red Flag Warning from 11 PM this evening to 2 PM PDT Friday for
East Washington Northeast (Zone 686)-East Washington
Northern Columbia Basin (Zone 673)-East Washington Okanogan
Highlands (Zone 687)-East Washington Palouse and Spokane
Area (Zone 674).
&&
$$
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SHORT TERM...TONIGHT AND FRIDAY
ISSUED AT 243 PM CDT THU AUG 22 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A SLOWLY
WEAKENING MCS MOVING OVER SOUTHERN LAKE MICHIGAN EARLY THIS
AFTERNOON. BACK EDGE OF THE CLOUD SHIELD ASSOCIATED WITH THIS MCS
IS MOVING SE OVER CENTRAL AND NORTHEAST WISCONSIN. DEWPOINTS ACROSS
NORTHERN WISCONSIN HAVE MIXED OUT INTO THE MIDDLE 40S...WHILE THE
DRIER AIR IS SLOWLY MOVING INTO EAST-CENTRAL WISCONSIN WHERE
READINGS ARE STILL IN THE UPPER 50S. PLENTY OF CLEAR SKIES UPSTREAM
OVER THE NORTHERN PLAINS AND SOUTH-CENTRAL CANADA WHERE SURFACE HIGH
PRESSURE IS SHIFTING TO THE SOUTHEAST. AS HIGH PRESSURE MOVES
TOWARDS THE REGION...FOG POTENTIAL TONIGHT AND TEMPS ARE THE MAIN
FORECAST CONCERNS.
TONIGHT...SURFACE HIGH PRESSURE WILL MOVE SOUTHEAST ACROSS THE
NORTHERN GREAT LAKES. AS THIS OCCURS...SKIES WILL BECOME CLEAR AND
WINDS WILL TURN LIGHT AND VARIABLE...SETTING UP GOOD RADIATIONAL
COOLING CONDITIONS. DEWPOINTS HAVE FALLEN INTO THE MIDDLE 40S
ACROSS NORTHERN WISCONSIN THIS AFTERNOON...WHILE THEY REMAIN IN THE
MIDDLE 50S TO LOWER 60S OVER CENTRAL AND EAST-CENTRAL WISCONSIN.
SOME MIXING OUT IS STILL EXPECTED...LOW TEMPS ARE EXPECTED TO
FALL NEAR OR BELOW THESE READINGS ACROSS MOST LOCATIONS. WITH THE
RECENT RAINFALL...WILL ADD PATCHY FOG TO THE FORECAST. LOWS NEAR 40
DEGREES AT THE COLD SPOTS OF N-C WISCONSIN AND THE MID 50S SOUTH.
FRIDAY...HIGH PRESSURE WILL REMAIN ACROSS THE AREA. OUTSIDE OF SCT
DIURNAL CU...SHOULD SEE PLENTY OF SUN AND LOW RELATIVE HUMIDITY.
HIGHS MOSTLY IN THE UPPER 70S TO LOWER 80S...LOCALLY COOLER NEAR
LAKE MICHIGAN.
.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY
ISSUED AT 243 PM CDT THU AUG 22 2013
CONCERNS THIS PERIOD WILL BE HEAT...WITH TEMPS EXPECTED TO RUN
WELL ABOVE NORMAL AND HUMIDITY LEVELS INCREASING THROUGH THE
PERIOD. MEDIUM RANGE MODELS CONTINUE TO BE IN VERY GOOD AGREEMENT
THROUGH THE EXTENDED WITH THE LARGE SCALE. STRONG RIDGE ANCHORED
BY 596 CENTER EXPECTED TO BE FOUND OVER THE CENTRAL PORTION OF THE
U.S. DIFFERENCES OCCUR WITH SMALL SCALE FEATURES...S/W`S MOVING
THROUGH SW FLOW OVER RIDGE AND WITH EXPECTED LOCATION OF SURFACE
BOUNDARY. OVERALL 850 TEMPS TO RUN WELL ABOVE NORMAL BY AT LEAST
TWO STANDARD DEVIATIONS FOR THIS TIME OF YEAR. LOCAL TEMPERATURE
TOOLS WOULD SUGGEST TEMPS INTO THE 90`S MONDAY ONWARD.
FOR MUCH OF THIS FORECAST USED A BLEND OF GFS/ECMWF...THOUGH WENT
MORE WITH EC TUE ONWARD AS GFS APPEARS TO BE TOO STRONG WITH
SURFACE FEATURES. WARM MID LEVEL TEMPS WOULD ALSO SUGGEST
ATMOSPHERE WOULD BE CAPPED FOR CONVECTION THOUGH SFC FRONT
EXPECTED TO MOVE NORTH THROUGH REGION SAT NIGHT/SUN. BOTH GFS AND
ECMWF DROP FRONT BACK SOUTH INTO NORTHERN WI WED/THU BEFORE
LIFTING IT BACK NORTH BEYOND THIS FORECAST PERIOD. WILL ONLY GO
WITH SLIGHT CHANCE/CHANCE POPS THROUGH PERIOD. OVERALL BEST CHANCE
FOR STRONG TO SEVERE STORMS...IF ANY..WOULD BE WED/THU TIME FRAME
AS SHEER INCREASES AS JET DROPS SOUTH.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1218 PM CDT THU AUG 22 2013
SHOWERS AND THUNDERSTORMS EXPECTED TO REMAIN SOUTH OF
THE TAF SITES THIS AFTERNOON. AS STORMS OVER SOUTHERN WISCONSIN EXIT
ACROSS SOUTHERN LAKE MICHIGAN...WILL SEE DECREASING CLOUDS DURING
THE AFTERNOON. HIGH PRESSURE WILL SETTLE ACROSS THE REGION
TONIGHT. WITH CLEAR SKIES AND LIGHT WINDS...PATCHY GROUND FOG WILL
DEVELOP LATE TONIGHT AND EARLY FRIDAY MORNING. THE FOG WILL BE MORE
DENSE/WIDESPREAD OVER NORTH-CENTRAL WISCONSIN COMPARED TO ELSEWHERE.
ONCE THE FOG BURNS OFF...VFR CONDITIONS TO RETURN.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TE
AVIATION.......MPC