Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/08/13
AREA FORECAST DISCUSSION
NWS TUCSON AZ
250 AM MST FRI SEP 6 2013
.SYNOPSIS...A BIT MORE AREAL COVERAGE IN THUNDERSTORMS AS A WEAK
DISTURBANCE ALOFT MOVES ACROSS THE AREA. DEEPER TROPICAL MOISTURE
WILL RETURN TO THE AREA FROM THE SOUTH THIS WEEKEND FOR AN INCREASE
IN SHOWERS AND THUNDERSTORMS BY SUNDAY WITH SHOWERS CONTINUING
THROUGH THE EARLY PART OF NEXT WEEK.
&&
.DISCUSSION...INFRARED SATELLITE IMAGERY THIS MORNING SHOWED CLEAR
TO PARTLY CLOUDY SKIES ACROSS SRN AZ. PRECIPITABLE WATER VALUES ARE
UP VERSUS 24 HOURS AGO WITH VALUES GENERALLY BETWEEN 1.10"-1.30"
WITH DEEPER MOISTURE ACROSS SRN SONORA MEXICO AND IN THE GULF OF
CALIFORNIA. 2 AM WATER VAPOR IMAGERY SHOWED A WEAK DISTURBANCE SSW
OF EL PASO...MOVING WNW AROUND 20-25 MPH WHICH WOULD PLACE IT NEAR
DOUGLAS AROUND 7 AM AND TUCSON AROUND 11 AM. 06Z NAMDNG5 AND RECENT
RUNS OF HRRR ARE INDICATING A BIT MORE ACTIVE AFTERNOON. THUS HAVE
UPPED POPS THIS AFTERNOON MAINLY ACROSS ERN PIMA/PINAL/SANTA CRUZ
COUNTIES. STILL ON THE DRY SIDE AT THE LOWER ELEVATIONS THUS WILL
SEE LOCALIZED GUSTS UP TO 50 MPH AND CAN`T RULE OUT AREAS OF BLOWING
DUST...ESPECIALLY IN PINAL COUNTY. SHOULD ALSO SEE HIGHLY LOCALIZED
HEAVY RAINERS. STORMS WILL CONTINUE TO ROLL OUT INTO THE LOWER
DESERTS EARLY THIS EVENING. HIGHS TODAY A FEW DEGREES COOLER THAN
THURSDAY.
MAIN THEME FOR THE REMAINDER OF THE FORECAST CYCLE WILL BE WETTER
CONDITIONS AS TROPICAL MOISTURE FROM TS LORENA STREAMS NORTH THIS
WEEKEND WITH CONTINUED FLOW FROM THE SOUTH THROUGH MUCH OF NEXT
WEEK. COULD RUN INTO A PERIOD WHERE SOME PARTS OF THE AREA WILL NEED
TO BE UNDER FLASH FLOOD WATCH...BUT AS DAYSHIFT POINTED OUT
YESTERDAY IT WILL BE HARD TO PINPOINT WHEN THE BEST CHANCES FOR THIS
TO OCCUR. THERE IS THE POTENTIAL THAT RAINFALL OVER THE NEXT WEEK
COULD BE A 2013 MONSOON SAVER FOR SOME SPOTS...WHILE ALSO ADDING TO
THE NEAR RECORD MONSOON RAINFALL THAT SOME AREAS HAVE ALREADY SEEN
THIS MONSOON.
&&
.AVIATION...ISOLATED TO OCCASIONALLY SCT -SHRA/-TSRA DEVELOPING
TODAY AFTER 18Z AND MAINLY CONFINED TO AREAS ALONG THE INTERNATIONAL
BORDER...AS WELL AS MOUNTAINS. SURFACE WIND GENERALLY LIGHT AND FROM
THE EAST OVERNIGHT...BECOMING SOUTHEAST 8-12 KTS THIS AFTERNOON
AFTERNOON...BUT GUSTY AT TIMES...WITH LOCALIZED STRONGER GUSTS FROM
-TSRA POSSIBLE. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...DRIER AIR WILL GENERALLY LIMIT THUNDERSTORM
POTENTIAL TODAY WITH ONLY ISOLATED COVERAGE EXPECTED. A STRONG
MOISTURE INCREASE FROM THE SOUTH WILL BRING A MUCH BETTER CHANCE OF
SHOWERS AND THUNDERSTORMS BY SUNDAY INTO EARLY NEXT WEEK. IN THE
MEANTIME...GUSTY EASTERLY WINDS OF UP TO 20 MPH CAN BE EXPECTED
TODAY.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
950 PM MDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 930 PM MDT SAT SEP 7 2013
THE EVENING SOUNDING SHOWED DRIER AIR WITH PRECIPITABLE WATER AT
TWO THIRDS OF AN INCH. THAT DID NOT LAST LONG AS THE ENVIRONMENT
IS BEING MODIFIED BEFORE THE NEXT MOISTURE SURGE ARRIVES
(DISCUSSED IN BETTER DETAIL BELOW). OUTFLOW BOUNDARIES HAS BEEN
TRIGGERING ADDITIONS STORMS THIS EVENING. THESE STORMS HAVE BEEN
PULSE TYPES AND NOT STAYING FOR TOO LONG AT ONE SPOT AS STEERING
FLOW IS SOUTHERLY AT 15-20 KTS. THIS EVENING CONVECTIVE ACTIVITY
SHOULD WANE AFTER MIDNIGHT PER RAP MODEL...HOWEVER AN ARIZONA
SHORT WAVE MOVES INTO SE UTAH LATE TONIGHT.
&&
.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 343 PM MDT SAT SEP 7 2013
SHOWER AND THUNDERSTORM DEVELOPMENT EARLY THIS AFTERNOON HAS AGAIN
FAVORED THE NORTHERN MOUNTAINS. HOWEVER SATELLITE AND RADAR TRENDS
INDICATE THAT THE OTHER MOUNTAIN AREAS ARE NOT FAR BEHIND.
MOISTURE HAS INCREASED A LITTLE OVER THE AREA TODAY...WITH MORE TO
COME AS THE MAIN MONSOONAL PLUME SHIFTS EAST TONIGHT THROUGH
SUNDAY. THIS INCREASE IN MOISTURE IS THE RESULT OF A SIGNIFICANT
CHANGE IN THE LARGE SCALE PATTERN THROUGH THE NEXT COUPLE OF DAYS.
THE LOW PRESSURE SYSTEM THAT HAS BEEN PARKED OVER THE PACIFIC
NORTHWEST HAS BEGUN TO SHIFT EASTWARD...AND WILL OPEN UP AND REACH
THE NORTHERN ROCKIES ON SUNDAY. ALSO AN ASSOCIATED AND TRAILING
TROUGH ALONG THE WEST COAST WILL SHIFT INTO THE GREAT BASIN DURING
THE SAME TIME FRAME. THIS WILL PUSH THE CENTER OF MONSOONAL
MOISTURE PLUME TO THE EAST AND OVER EASTERN UT/WESTERN CO.
THEREFORE WE CAN EXPECT A MORE ACTIVE PERIOD THROUGH THE NEXT
COUPLE OF DAYS. ALSO ANY EMBEDDED DISTURBANCES OR INTERACTING
BOUNDARIES WILL ENHANCE CONVECTIVE ACTIVITY. ONE DISTURBANCE
MOVING UP FROM EASTERN AZ/WESTERN NM WILL REACH THE FORECAST AREA
LATER THIS EVENING. WHILE THE TIMING IS NOT THE BEST FOR DIURNAL
HELP. SATELLITE AND RADAR LOOPS INDICATE THAT WE COULD SEE AN AREA
OF SHOWERS AND THUNDERSTORMS REACH OUR SOUTHERN EDGE LATER THIS
EVENING...THEN MOVE NORTH OVERNIGHT. PRECIPITABLE WATER VALUES
WILL INCREASE TO OVER AN INCH ALONG THE UT/CO BORDER BY SUN
MORNING AND BY AN ADDITIONAL QUARTER INCH SUN NIGHT. THIS DEEPER
MOISTURE WILL EXTEND CLEAR TO THE WY BORDER. ALSO THE FLOW ALOFT
WILL INCREASE AS JET ENERGY WRAPS AROUND THE WESTERN TROUGH AND
BRUSHES THE NORTHWEST CORNER LATE SUN-SUN NIGHT. THIS WILL PROVIDE
SOME VENTILATION TO STORMS...BUT ALSO WILL RESULT IN A LITTLE
BETTER STORM MOTION. THEREFORE SOME STRONGER STORMS MAY DEVELOP
SUN AFTERNOON...ESPECIALLY NORTH. BUT THE SOUTH WILL SEE THE
DEEPEST MOISTURE. HEAVY RAIN WILL BE POSSIBLE WITH STORMS WITH THE
BEST ACCUMULATIONS OVER THE SOUTH WHERE THE FLOW IS WEAKEST.
A COOLING TREND IS EXPECTED DUE TO THE INCREASED CLOUDS...SHOWERS
AND THUNDERSTORMS. HOWEVER READINGS ACROSS THE AREA WILL STILL
REMAIN ABOVE NORMAL THROUGH THE SHORT TERM PERIOD.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 343 PM MDT SAT SEP 7 2013
THE FLOW PATTERN ACROSS THE CONUS WILL BE MAKING A SUBTLE AND
TEMPORARY SHIFT TOWARD THE MID WEEK PERIOD. THE CURRENT COASTAL
TROUGHING AND AMPLIFIED PLAINS RIDGE SET UP WILL BE INFLUENCED BY A
DIP IN THE POLAR JET AND PASSING WAVE MOVING ACROSS THE NORTHERN
STATES DURING THIS TIME PERIODS. IN THE WAKE OF THE NORTHERN
SYSTEM...LOW PRESSURE WILL BE EXPANDING ACROSS THE GREAT BASIN WHILE
THE SUB TROPICAL HIGH IS PUSHED TO THE SOUTHEAST STATES AND
PACIFIC HIGH PRESSURE BUILDS ALONG THE WEST COAST. AS WE MOVE
FARTHER ALONG INTO THE SEASONAL TRANSITION PERIOD...THE MODELS
BEGIN TO STRUGGLE TO FIND AGREEMENT AND THIS IS APPARENT BY THE DAY
6 AND 7 TIME PERIOD.
MONDAY INTO TUESDAY IS LOOKING MORE LIKE THE COOLER AND WETTER
PORTION OF THE FORECAST. FORECAST PRECIPITABLE WATER NEAR GJT IS
PEAKING OVER AN INCH ACCORDING TO MODEL TIME SERIES WHICH WILL BE
CLOSING TOWARD 175 PERCENT OF NORMAL FOR EARLY SEPTEMBER. LARGE
SCALE ASCENT WILL BE PROVIDED BY TRAILING ENERGY OF THE NORTHERN
STREAM WAVE LINKING TO AN ORGANIZING AREA OF LOW PRESSURE OVER
SOUTHEAST CALIFORNIA. A JET AXIS OVERHEAD AND A WEAKENING SURFACE
BOUNDARY WILL ALSO HELP FOCUS THE LIFT OVER PORTIONS OF OUR CWA
DURING THIS TIME PERIOD....SO POPS CONTINUE TO BE HEDGED UPWARD.
HEAVY RAIN WILL BE A THREAT IN THE WARM CORE ENVIRONMENT...BUT STORM
MOVEMENT SHOULD LEAVE ONLY A LOCALIZED FLOODING THREAT.
BIGGER CHALLENGE WILL BE TEMPERATURES AS CLOUD COVER AND
PRECIPITATION LOOK TO INHIBIT INSOLATION OVER MUCH OF OUR CWA.
GUIDANCE NUMBERS ARE MERGING TOWARD HIGHS SLIGHTLY BELOW NORMAL AND
CONTINUED IN THIS DIRECTION...HOWEVER IF CLOUD COVER IS AS THICK AS
EXPECTED THESE MAY BE A TAD TO WARM IN SPOTS.
WEDNESDAY INTO THURSDAY THE NORTHERN STREAM WAVE FULLY ABSORBS INTO
THE GREAT LAKES TROUGH AND HELPS DIG IT TOWARD THE MID ATLANTIC.
THIS ALLOWS THE SUB-TROP RIDGE TO BULGE BACK TO THE WEST AND MERGE
WITH A REX HIGH THAT HAS PUSHED INTO THE NORTHERN ROCKIES.
SQUEEZED BETWEEN THIS ELONGATED AREA OF HIGH PRESSURE AND ANOTHER
AREA OFF THE CALIFORNIA COAST...WILL BE LOW PRESSURE LIFTING ACROSS
THE GREAT BASIN. QG FIELDS SHOW THE STRONGEST LIFT REMAINING TO
OUR WEST ATTM...BUT PLENTY OF MOISTURE WILL CONTINUE TO BE POINTED
UP THROUGH THE 4 CORNERS REGION. THURSDAY MODELS ARE TRENDING
TOWARD A MORE ACTIVE DAY WITH A LOBE OF ENERGY ALONG WITH A PIECE
OF THE JET MOVING INTO THE 4 CORNERS. SHEAR AND INSTABILITY LOOK
STRONG ENOUGH FOR BETTER STORM ORGANIZATION. AN UPSTREAM WAVE
ARRIVING TO THE WEST COAST IS NOT WELL HANDLED ATTM AND WILL HAVE
A STRONG IMPACT TO THE FATE OF THE GREAT BASIN LOW AND THE ARRIVAL
OF DRIER AIR IN THE WESTERLIES BEHIND IT...SO CONFIDENCE AND POPS
ARE LOW TOWARD THE WEEKEND. TEMPERATURES FROM WEDNESDAY ONWARD
SHOULD BE SEASONAL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 950 PM MDT SAT SEP 7 2013
ISOLATED -SHRA/-TSRA FROM 06Z-12Z OVER SE UTAH/SW COLORADO WILL
SPREAD NORTH ON SUNDAY. AFTER 18Z SUNDAY...SCATTERED -SHRA/-TSRA
IS EXPECTED WITH LOCAL VRB20G35KT +SHRA/+TSRA LIMITING VIS AND
LOWER CIGS. MOUNTAIN TOP MAY BE OCCASIONALLY OBSCURED.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
UPDATE...PF
SHORT TERM...EH
LONG TERM...15
AVIATION...PF
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
930 PM MDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 930 PM MDT SAT SEP 7 2013
THE EVENING SOUNDING SHOWED DRIER AIR WITH PRECIPITABLE WATER AT
TWO THIRDS OF AN INCH. THAT DID NOT LAST LONG AS THE ENVIRONMENT
IS BEING MODIFIED BEFORE THE NEXT MOISTURE SURGE ARRIVES
(DISCUSSED IN BETTER DETAIL BELOW). OUTFLOW BOUNDARIES HAS BEEN
TRIGGERING ADDITIONS STORMS THIS EVENING. THESE STORMS HAVE BEEN
PULSE TYPES AND NOT STAYING FOR TOO LONG AT ONE SPOT AS STEERING
FLOW IS SOUTHERLY AT 15-20 KTS. THIS EVENING CONVECTIVE ACTIVITY
SHOULD WANE AFTER MIDNIGHT PER RAP MODEL...HOWEVER AN ARIZONA
SHORT WAVE MOVES INTO SE UTAH LATE TONIGHT.
&&
.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 343 PM MDT SAT SEP 7 2013
SHOWER AND THUNDERSTORM DEVELOPMENT EARLY THIS AFTERNOON HAS AGAIN
FAVORED THE NORTHERN MOUNTAINS. HOWEVER SATELLITE AND RADAR TRENDS
INDICATE THAT THE OTHER MOUNTAIN AREAS ARE NOT FAR BEHIND.
MOISTURE HAS INCREASED A LITTLE OVER THE AREA TODAY...WITH MORE TO
COME AS THE MAIN MONSOONAL PLUME SHIFTS EAST TONIGHT THROUGH
SUNDAY. THIS INCREASE IN MOISTURE IS THE RESULT OF A SIGNIFICANT
CHANGE IN THE LARGE SCALE PATTERN THROUGH THE NEXT COUPLE OF DAYS.
THE LOW PRESSURE SYSTEM THAT HAS BEEN PARKED OVER THE PACIFIC
NORTHWEST HAS BEGUN TO SHIFT EASTWARD...AND WILL OPEN UP AND REACH
THE NORTHERN ROCKIES ON SUNDAY. ALSO AN ASSOCIATED AND TRAILING
TROUGH ALONG THE WEST COAST WILL SHIFT INTO THE GREAT BASIN DURING
THE SAME TIME FRAME. THIS WILL PUSH THE CENTER OF MONSOONAL
MOISTURE PLUME TO THE EAST AND OVER EASTERN UT/WESTERN CO.
THEREFORE WE CAN EXPECT A MORE ACTIVE PERIOD THROUGH THE NEXT
COUPLE OF DAYS. ALSO ANY EMBEDDED DISTURBANCES OR INTERACTING
BOUNDARIES WILL ENHANCE CONVECTIVE ACTIVITY. ONE DISTURBANCE
MOVING UP FROM EASTERN AZ/WESTERN NM WILL REACH THE FORECAST AREA
LATER THIS EVENING. WHILE THE TIMING IS NOT THE BEST FOR DIURNAL
HELP. SATELLITE AND RADAR LOOPS INDICATE THAT WE COULD SEE AN AREA
OF SHOWERS AND THUNDERSTORMS REACH OUR SOUTHERN EDGE LATER THIS
EVENING...THEN MOVE NORTH OVERNIGHT. PRECIPITABLE WATER VALUES
WILL INCREASE TO OVER AN INCH ALONG THE UT/CO BORDER BY SUN
MORNING AND BY AN ADDITIONAL QUARTER INCH SUN NIGHT. THIS DEEPER
MOISTURE WILL EXTEND CLEAR TO THE WY BORDER. ALSO THE FLOW ALOFT
WILL INCREASE AS JET ENERGY WRAPS AROUND THE WESTERN TROUGH AND
BRUSHES THE NORTHWEST CORNER LATE SUN-SUN NIGHT. THIS WILL PROVIDE
SOME VENTILATION TO STORMS...BUT ALSO WILL RESULT IN A LITTLE
BETTER STORM MOTION. THEREFORE SOME STRONGER STORMS MAY DEVELOP
SUN AFTERNOON...ESPECIALLY NORTH. BUT THE SOUTH WILL SEE THE
DEEPEST MOISTURE. HEAVY RAIN WILL BE POSSIBLE WITH STORMS WITH THE
BEST ACCUMULATIONS OVER THE SOUTH WHERE THE FLOW IS WEAKEST.
A COOLING TREND IS EXPECTED DUE TO THE INCREASED CLOUDS...SHOWERS
AND THUNDERSTORMS. HOWEVER READINGS ACROSS THE AREA WILL STILL
REMAIN ABOVE NORMAL THROUGH THE SHORT TERM PERIOD.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 343 PM MDT SAT SEP 7 2013
THE FLOW PATTERN ACROSS THE CONUS WILL BE MAKING A SUBTLE AND
TEMPORARY SHIFT TOWARD THE MID WEEK PERIOD. THE CURRENT COASTAL
TROUGHING AND AMPLIFIED PLAINS RIDGE SET UP WILL BE INFLUENCED BY A
DIP IN THE POLAR JET AND PASSING WAVE MOVING ACROSS THE NORTHERN
STATES DURING THIS TIME PERIODS. IN THE WAKE OF THE NORTHERN
SYSTEM...LOW PRESSURE WILL BE EXPANDING ACROSS THE GREAT BASIN WHILE
THE SUB TROPICAL HIGH IS PUSHED TO THE SOUTHEAST STATES AND
PACIFIC HIGH PRESSURE BUILDS ALONG THE WEST COAST. AS WE MOVE
FARTHER ALONG INTO THE SEASONAL TRANSITION PERIOD...THE MODELS
BEGIN TO STRUGGLE TO FIND AGREEMENT AND THIS IS APPARENT BY THE DAY
6 AND 7 TIME PERIOD.
MONDAY INTO TUESDAY IS LOOKING MORE LIKE THE COOLER AND WETTER
PORTION OF THE FORECAST. FORECAST PRECIPITABLE WATER NEAR GJT IS
PEAKING OVER AN INCH ACCORDING TO MODEL TIME SERIES WHICH WILL BE
CLOSING TOWARD 175 PERCENT OF NORMAL FOR EARLY SEPTEMBER. LARGE
SCALE ASCENT WILL BE PROVIDED BY TRAILING ENERGY OF THE NORTHERN
STREAM WAVE LINKING TO AN ORGANIZING AREA OF LOW PRESSURE OVER
SOUTHEAST CALIFORNIA. A JET AXIS OVERHEAD AND A WEAKENING SURFACE
BOUNDARY WILL ALSO HELP FOCUS THE LIFT OVER PORTIONS OF OUR CWA
DURING THIS TIME PERIOD....SO POPS CONTINUE TO BE HEDGED UPWARD.
HEAVY RAIN WILL BE A THREAT IN THE WARM CORE ENVIRONMENT...BUT STORM
MOVEMENT SHOULD LEAVE ONLY A LOCALIZED FLOODING THREAT.
BIGGER CHALLENGE WILL BE TEMPERATURES AS CLOUD COVER AND
PRECIPITATION LOOK TO INHIBIT INSOLATION OVER MUCH OF OUR CWA.
GUIDANCE NUMBERS ARE MERGING TOWARD HIGHS SLIGHTLY BELOW NORMAL AND
CONTINUED IN THIS DIRECTION...HOWEVER IF CLOUD COVER IS AS THICK AS
EXPECTED THESE MAY BE A TAD TO WARM IN SPOTS.
WEDNESDAY INTO THURSDAY THE NORTHERN STREAM WAVE FULLY ABSORBS INTO
THE GREAT LAKES TROUGH AND HELPS DIG IT TOWARD THE MID ATLANTIC.
THIS ALLOWS THE SUB-TROP RIDGE TO BULGE BACK TO THE WEST AND MERGE
WITH A REX HIGH THAT HAS PUSHED INTO THE NORTHERN ROCKIES.
SQUEEZED BETWEEN THIS ELONGATED AREA OF HIGH PRESSURE AND ANOTHER
AREA OFF THE CALIFORNIA COAST...WILL BE LOW PRESSURE LIFTING ACROSS
THE GREAT BASIN. QG FIELDS SHOW THE STRONGEST LIFT REMAINING TO
OUR WEST ATTM...BUT PLENTY OF MOISTURE WILL CONTINUE TO BE POINTED
UP THROUGH THE 4 CORNERS REGION. THURSDAY MODELS ARE TRENDING
TOWARD A MORE ACTIVE DAY WITH A LOBE OF ENERGY ALONG WITH A PIECE
OF THE JET MOVING INTO THE 4 CORNERS. SHEAR AND INSTABILITY LOOK
STRONG ENOUGH FOR BETTER STORM ORGANIZATION. AN UPSTREAM WAVE
ARRIVING TO THE WEST COAST IS NOT WELL HANDLED ATTM AND WILL HAVE
A STRONG IMPACT TO THE FATE OF THE GREAT BASIN LOW AND THE ARRIVAL
OF DRIER AIR IN THE WESTERLIES BEHIND IT...SO CONFIDENCE AND POPS
ARE LOW TOWARD THE WEEKEND. TEMPERATURES FROM WEDNESDAY ONWARD
SHOULD BE SEASONAL.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 343 PM MDT SAT SEP 7 2013
ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
CONTINUES TO DEVELOP THIS AFTERNOON...FAVORING THE HIGHER TERRAIN.
GUSTY AND ERRATIC OUTFLOW WINDS...HEAVY RAIN AND SMALL HAIL WILL
BE ASSOCIATED WITH THE STRONGER THUNDERSTORMS...MAINLY BEFORE 03Z
THIS EVENING. MOISTURE WILL CONTINUE TO SURGE BACK INTO THE REGION
ESPECIALLY AFTER 06Z TONIGHT. IN ADDITION A DISTURBANCE MOVING UP
FROM THE SOUTH WILL REACH THE SOUTHERN PORTION OF THE AREA LATE
THIS EVENING BRINGING A BETTER CHANCE OF NOCTURNAL SHOWERS AND
THUNDERSTORMS. LOOK FOR AN UPTICK IN CONVECTIVE ACTIVITY ON
SUNDAY...WITH AN EARLIER ONSET TO SHOWERS AND THUNDERSTORMS AS
WELL.
EXPECT LOCAL MVFR CIGS AND VSBYS NEAR THE STRONGER THUNDERSTORMS
THIS AFTERNOON AND AGAIN ON SUNDAY...ESPECIALLY ACROSS THE
MOUNTAINS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
UPDATE...PF
SHORT TERM...EH
LONG TERM...15
AVIATION...EH
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
357 PM MDT FRI SEP 6 2013
.SHORT TERM...PRESENT FORECAST GRIDS NEED LITTLE WORK. ONGOING
CONVECTION SHOULD CONFINE ITSELF MOSTLY TO THE FOOTHILLS THIS
EVENING ALTHOUGH SEVERAL RECENT HRRR RUNS WANT TO BRING A BIT OF
IT SOUTHEAST ACROSS THE NORTHERN/CENTRAL PORTIONS OF THE URBAN
CORRIDOR TOWARDS 00Z.
SATURDAY SHOULD BE CLOSE TO A CARBON COPY OF TODAY AS THE UPPER
LEVEL ANTICYCLONE KEEPS ITS FURNACE-LIKE GRIP ON THE REGION.
WELL ABOVE NORMAL TEMPERATURES EXPECTED AGAIN TOMORROW AFTERNOON
WITH SOME CONVECTION AGAIN BREAKING OUT OVER THE HIGHER TERRAIN.
CONVECTIVE PROBABILITIES SATURDAY WILL DECREASE QUICKLY AS ONE
MOVES AWAY FROM THE MOUNTAINS...SIMILAR TO TODAY.
.LONG TERM...SOME CHANGES AS WE GET INTO NEXT WEEK. UPPER RIDGE
WILL SHIFT EAST ALLOWING FOR MOISTURE TO INCREASE AGAIN BY MONDAY.
MEANWHILE A SHORT WAVE TROUGH MOVING ACROSS THE NORTHERN U.S.
BORDER WILL PUSH SOME LESS HOT LOW LEVEL AIR SOUTHWARD ON MONDAY.
THE MAIN IMPACTS LOOK LIKE THE LOW LEVEL COOLING...AND HIGH LEVEL
MOISTENING. THIS COULD WIND UP BEING SIMILAR TO THE COOLER PERIODS
WE HAD 5 TO 10 DAYS AGO WHEN IT WAS WARM AND MOIST...BUT NOT WARM
ENOUGH TO SUPPORT LOTS OF CONVECTION DUE TO THE CLOUD COVER AND
NOT MUCH COOLING ALOFT. MODELS WANT TO PRODUCE INCREASED
PRECIPITATION IN THE MONDAY THROUGH THURSDAY TIME PERIOD...BUT I
AM HESITANT TO RAISE POPS TOO MUCH DUE TO THE STABILITY ISSUE.
THERE WILL PROBABLY BE MORE CONVECTIVE ACTIVITY...BUT OVERALL IT
WILL LIKELY BE WEAK. POSSIBLE EXCEPTION WILL BE MONDAY WHEN THERE
COULD BE BOTH LOW LEVEL CONVERGENCE AND A LITTLE UPPER LEVEL
DIVERGENCE THAT COULD SUSTAIN SOMETHING MORE ORGANIZED.
TEMPERATURES WILL BE AFFECTED AS MUCH BY THE CLOUD COVER AS THE
ACTUAL COOLING...MINIMUM TEMPERATURES MAY STILL BE PRETTY MILD.
SLIGHT WARMING AND DRYING DURING THE LATER PART OF THE WEEK BUT WE
WILL STILL BE UNDER SW FLOW ALOFT AND PROBABLY STILL A LOT OF HIGH
CLOUDINESS. RIDGE REBUILDS BY NEXT WEEKEND...HARD TO TELL HOW MUCH
CLOUD COVER THERE WILL BE...IF IT DRIES OUT A BIT WE WILL LIKELY
BE NEAR RECORD HIGHS AGAIN...THOUGH PROBABLY NOT AS HOT AS WE ARE
NOW.
&&
.AVIATION...THUNDERSTORM THREAT LOOKS PRETTY SMALL AT THE
TERMINALS THIS EVENING AND AGAIN ON SATURDAY. WINDS ARE BEHAVING
ABOUT AS EXPECTED AT THIS POINT. SOME OF THE SMALLER SCALE MODELS
ARE SUGGESTING A MODERATELY STRONG OUTFLOW BOUNDARY WILL MOVE
ACROSS THE TERMINALS TOWARDS 00Z. PRESENT TAFS HAVE THIS SUGGESTED
WITH THE WESTERLY WINDS AT 00Z. NORMAL DIURNAL PATTERNS LATER
TONIGHT.
&&
.HYDROLOGY...CONVECTIVE ACTIVITY IS MOVING NORTHWARD AT A DECENT
CLIP THIS AFTERNOON. STRONG STORMS MOVED ACROSS THE HIGH PARK BURN
AREA EARLY THIS AFTERNOON AND ADDITIONAL STORMS MAY CROSS THAT
AREA AS WELL AS FOUR MILE LATER TODAY. THESE STORMS WILL POSE SOME
FLOODING THREAT. A SIMILAR SITUATION WILL EXIST SATURDAY
AFTERNOON.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...ET
LONG TERM....GIMMESTAD
AVIATION...ET
AREA FORECAST DISCUSSION
NWS NEW YORK NY
749 AM EDT FRI SEP 6 2013
.SYNOPSIS...
CANADIAN HIGH PRESSURE WILL BUILD IN TODAY...AND THEN DRIFT TO THE
SOUTH TONIGHT THROUGH SATURDAY NIGHT. A COLD FRONT WILL PASS
THROUGH ON SUNDAY...FOLLOWED BY HIGH PRESSURE FROM SUNDAY NIGHT
THROUGH WEDNESDAY. ANOTHER COLD FRONT WILL APPROACH ON THURSDAY...
AND PASS THROUGH THURSDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE WEAKENS AND SETTLES DIRECTLY OVER THE REGION.
A BROAD WEAK UPPER LEVEL TROUGH MOVES ACROSS THE REGION WHICH
WILL BRING SOME CLOUDS BUT THINKING THAT THE SUBSIDENCE IS THE
GREATER FACTOR HERE WITH A MOSTLY SUNNY SKY PREVAILING. THE CENTER
OF HIGH PRESSURE WILL TREND SOUTH OF THE REGION BY THE LATE
AFTERNOON. A WEAK PRESSURE GRADIENT WILL ENABLE FOR LIGHT
WINDS...AND THE SYNOPTIC FLOW WILL ENABLE FOR A WEAK SEA BREEZE
LATE IN THE AFTERNOON BUT TEMPERATURES ARE FORECAST TO BE ONLY A
FEW DEGREES ABOVE SEA SURFACE TEMPERATURES.
THE AIR MASS WILL BE SLOW TO MODERATE WITH THE WEAK BOUNDARY LAYER
WINDS DESPITE FORECAST MIXING UP TO AROUND 850MB AND WIND DIRECTION
WILL BE VARIABLE. THIS IS CONVEYED THROUGH THE EVOLUTION OF THE
850MB TEMPERATURE FIELD. THE TEMPS WILL STAY MAINLY BETWEEN 5 AND 7
DEGREES C THROUGH THE DAY. MAX TEMPS LOOKED RELATIVELY SIMILAR
BETWEEN MAV AND MET WITH THE CORRESPONDING NUMERICAL MODEL BUFKIT
SOUNDINGS OF GFS AND NAM SHOWING MIXING JUST BELOW AND ABOVE 850MB
RESPECTIVELY. THERE ARE SIMILAR DIFFERENCES BETWEEN THE RUC AND SREF
SOUNDINGS AS WELL. MAX TEMP FORECAST GENERALLY IN THE UPPER 60S
AND LOWER 70S...WHICH WILL BE ABOUT 5-8 DEGREES BELOW AVG.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
FOR TONIGHT...HIGH PRESSURE CONTINUES TO SLOWLY WEAKEN AND MOVE
SOUTH OF THE AREA AS THE UPPER LEVEL TROUGH CONTINUES TO WEAKEN
AND SHIFT WELL EAST OF THE AREA. THIS WILL SET UP A SOUTHWEST WIND
FLOW...WHICH WILL ALLOW FOR SLIGHTLY WARMER LOW TEMPS AND
ESSENTIALLY A MODERATION OF THE AIR MASS. THE 850MB TEMPS ACTUALLY
INCREASE SEVERAL DEGREES DURING THE NIGHT. CLEAR SKIES AND LIGHT
WINDS ESPECIALLY ACROSS THE INTERIOR HOWEVER WILL PROVIDE ANOTHER
GOOD NIGHT OF RADIATIONAL COOLING WHICH WILL OFFSET THE LIGHT
SOUTHWEST FLOW ADVECTING IN WARMER AIR. LOWS WILL BE RELATIVELY
SIMILAR TO THE PREVIOUS NIGHT FOR THE COASTAL AREAS AND URBAN
SECTIONS OF NEW YORK AND NEW JERSEY BUT A FEW DEGREES WARMER
ACROSS THE INTERIOR.
LOWS WERE A BLEND OF MET AND GMOS WITH GREATER WEIGHT FOR MET
GUIDANCE WHICH SHOWS A WIDER RANGE OF TEMPERATURES...WHICH FITS
WELL WITH GOOD RADIATIONAL COOLING.
FOR SATURDAY...HIGH PRESSURE CONTINUES TO WEAKEN AND PUSH SOUTH
OF THE REGION...WITH SOUTHWEST FLOW INCREASING. IN THE UPPER
LEVELS...A NORTHWEST FLOW WILL PREVAIL. TEMPERATURES WILL MAKE A
REBOUND...WITH 850 MB TEMPS INCREASING TO BETWEEN 12 AND 15
DEGREES C AND BOUNDARY LAYER WINDS INCREASE WITH VERTICAL MIXING
UP TO AROUND 900MB. INCREASING CLOUDS WILL START INFILTRATE THE
REGION FROM THE NORTH DURING THE AFTERNOON WELL UPSTREAM OF A
DEEPER SHORTWAVE MOVING INTO ONTARIO. THE HIGHS WERE A BLEND OF
MET AND MAV WITH GREATER WEIGHT TOWARDS THE MET GUIDANCE WHICH
SHOWS GREATER WARMTH ACROSS THE INTERIOR AND COOLER VALUES ALONG
THE COAST. AGAIN...THIS IS SHOWING GREATER RANGE. THIS TIME IT IS
BECAUSE OF THE DOWNSLOPE ACROSS INTERIOR AND MARINE INFLUENCE
ALONG THE COASTAL AREAS. THESE HIGHS WILL BE PRETTY CLOSE TO
NORMAL VALUES.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
MODELS STILL CLOSELY AGREE ON IDEA OF AN UPPER RIDGE OVER THE PLAINS
STATES AND TROUGH FROM THE MID ATLANTIC INTO EASTERN CANADA TO
START. A VIGOROUS SHORTWAVE WILL DIVE INTO THE BASE OF THE TROUGH ON
SUNDAY...DRIVING A COLD FRONT THROUGH. THIS FRONT WILL BE FOLLOWED
BY A GUSTY NW-N FLOW AS HIGH PRESSURE BUILDS QUICKLY...AND AFTER A
DAY OF NEAR AVG TEMPS ON SUNDAY...A BRIEF COOLER SPELL WILL FOLLOW
FOR SUNDAY NIGHT INTO MON...WITH TEMPS A FEW DEG BELOW AVG.
LOW TEMPS BY MON MORNING COULD APPROACH 40 IN THE COLDEST INTERIOR
VALLEYS AS THE HIGH BUILDS QUICKLY OVERHEAD.
AS THE UPPER TROUGH LIFTS NE WELL INTO NE CANADA...FLOW ALOFT WILL
BECOME MORE ZONAL...ALLOWING THE UPPER HIGH TO BUILD E-WARD TO
THE MID ATLC AND SE COASTS AND A WARM FRONT TO PASS WELL TO OUR
NORTH ON TUE. TEMPS SHOULD SLOWLY WARM DURING MID WEEK...RISING TO
SLIGHTLY ABOVE AVG LEVELS WED AND THU. MULTIPLE SHORTWAVES
EMBEDDED IN THE FLOW SHOULD THEN CARVE OUT A NEW ERN TROUGH LATE
THIS WEEK...BRINGING ANOTHER COLD FRONT TOWARD THE AREA LATE IN
THE WEEK. TIMING OF THE FRONT STILL IN QUESTION...WHILE 00Z
GFS/ECMWF ARE IN AGREEMENT ON FROPA BY EARLY THU MORNING...THE
05/12Z ECMWF IDEA OF A DEEPER UPPER TROUGH AND SLOWER TIMING MAY
STILL BE PLAUSIBLE AND HAVE DELAYED FRONTAL APPROACH UNTIL DAYTIME
THU...AND FROPA UNTIL THU NIGHT...WITH SHOWERS AND POSSIBLE TSTMS.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE WILL REMAIN OVER THE TERMINALS TODAY.
VFR THRU THE TAF PERIOD.
LIGHT NORTH TO NORTH-NORTHEAST WINDS WILL VEER TO THE NORTHEAST THIS
MORNING. WINDS THEN WEAKEN AND SHIFT TO THE SOUTH THIS AFTERNOON.
WINDS SPEEDS WILL REMAIN 10KT OR LESS...WITH MOST TERMINALS BECOMING
LIGHT AND VARIABLE.
A WEAK SEA BREEZE IS POSSIBLE ALONG THE IMMEDIATE SOUTH COASTAL
AIRPORTS. AWAY FROM THE COAST...EXPECT LIGHT AND VARIABLE WINDS.
...NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP://WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: HIGH CONFIDENCE VFR FORECAST. WIND SHIFT
EXPECTED DURING THE AFTERNOON. TIMING MAY BE OFF BY AN HOUR OR TWO.
KLGA FCSTER COMMENTS: HIGH CONFIDENCE VFR FORECAST. WIND SHIFT
EXPECTED DURING THE AFTERNOON. TIMING MAY BE OFF BY AN HOUR OR TWO.
KEWR FCSTER COMMENTS: HIGH CONFIDENCE VFR FORECAST. WIND SHIFT
EXPECTED DURING THE AFTERNOON. TIMING MAY BE OFF BY AN HOUR OR TWO.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: HIGH CONFIDENCE VFR FORECAST. WINDS BECOME
LIGHT AND VARIABLE DURING THE AFTERNOON. TIMING MAY BE OFF BY AN
HOUR OR TWO.
KHPN FCSTER COMMENTS: HIGH CONFIDENCE VFR FORECAST. WINDS BECOME
LIGHT AND VARIABLE DURING THE AFTERNOON. TIMING MAY BE OFF BY AN
HOUR OR TWO.
KISP FCSTER COMMENTS: HIGH CONFIDENCE VFR FORECAST. WINDS BECOME
LIGHT AND VARIABLE DURING THE AFTERNOON. TIMING MAY BE OFF BY AN
HOUR OR TWO.
OUTLOOK FOR 12Z SAT THROUGH MON...
.SATURDAY-SATURDAY NIGHT...VFR.
.SUNDAY...ISOLATED SHOWERS WITH BRIEF MVFR CONDITIONS POSSIBLE.
.SUNDAY NIGHT-TUESDAY...VFR.
&&
.MARINE...
SUB SCA CONDITIONS EXPECTED THROUGH SATURDAY. COLD AIR ADVECTION
OVER THE WARMER WATERS WILL ALLOW FOR GUSTS UP TO 20 KT INTO THIS
MORNING. WIND GUSTS WILL THEN SUBSIDE LATE THIS MORNING AND
AFTERNOON AS A HIGH PRESSURE CENTER TO THE WEST MOVES CLOSER TO
THE AREA. THE NORTHERLY WIND FLOW WILL WEAKEN AND BECOME MORE
VARIABLE IN DIRECTION...BEFORE TURNING MORE SOUTHWESTERLY TONIGHT.
WINDS WILL PICK UP MORE ON SATURDAY TO AROUND 10-15 KT IN THE
AFTERNOON. SEAS WILL STAY MAINLY BETWEEN 2 TO 3 FT ON THE OCEAN
THROUGH SATURDAY.
SW FLOW AHEAD OF A COLD FRONT ON SUNDAY COULD BUILD THE OCEAN SEAS
OFF EASTERN LONG ISLAND TO 5 FT. POST-FRONTAL NW-N FLOW AS STRONG
HIGH PRESSURE BUILDS IN QUICKLY SHOULD GUST TO 25-30 ON THE OCEAN
AND THE ERN SOUND/BAYS SUNDAY NIGHT AND PERHAPS INTO PART OF MON
MORNING...WITH MAX OCEAN SEAS 6 FT DURING THAT TIME.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH THE MIDDLE OF
NEXT WEEK.
&&
.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.
&&
.CLIMATE..
THE LOW TEMPERATURE AT CENTRAL PARK SO FAR THIS MORNING WAS
57...THE COLDEST TEMPERATURE AT THE PARK SINCE JUNE 14TH WHEN THE
LOW WAS 53.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS/NEAR TERM/MARINE/HYDROLOGY...JM/GOODMAN
SHORT TERM...JM
LONG TERM/EQUIPMENT/CLIMATE...GOODMAN
AVIATION...BC
AREA FORECAST DISCUSSION
NWS NEW YORK NY
433 AM EDT FRI SEP 6 2013
.SYNOPSIS...
CANADIAN HIGH PRESSURE WEAKENS AND SETTLES DIRECTLY OVER THE
REGION TODAY BEFORE SHIFTING SOUTH OF THE AREA THIS AFTERNOON
THROUGH SATURDAY NIGHT. A COLD FRONT WILL PASS THROUGH ON
SUNDAY...FOLLOWED BY HIGH PRESSURE FROM SUNDAY NIGHT THROUGH
WEDNESDAY. A COLD FRONT WILL APPROACH ON THURSDAY...AND PASS
THROUGH THURSDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
RADIATIONAL COOLING GOING INTO THE EARLY MORNING HOURS WILL ALLOW THE
TEMPERATURES TO DROP WELL INTO THE 40S AND 50S FOR MOST LOCATIONS
WITH A CONTINUED DRYING AIRMASS. WINDS WILL ALSO LOWER AS THE
INFLUENCE OF HIGH PRESSURE IS MORE FELT AS IT DRAWS CLOSER TO THE
AREA.
HIGH PRESSURE WEAKENS AND SETTLES DIRECTLY OVER THE REGION. A
BROAD WEAK UPPER LEVEL TROUGH MOVES ACROSS THE REGION WHICH WILL
BRING SOME CLOUDS BUT THINKING THAT THE SUBSIDENCE IS THE GREATER
FACTOR HERE WITH A MOSTLY SUNNY SKY PREVAILING. THE CENTER OF
HIGH PRESSURE WILL TREND SOUTH OF THE REGION BY THE LATE
AFTERNOON. A WEAK PRESSURE GRADIENT WILL ENABLE FOR LIGHT WINDS
AND THE SYNOPTIC FLOW WILL ENABLE FOR A WEAK SEA BREEZE LATE IN
THE AFTERNOON BUT TEMPERATURES ARE FORECAST TO BE ONLY A FEW
DEGREES ABOVE SEA SURFACE TEMPERATURES.
THE AIRMASS WILL BE SLOW TO MODERATE WITH THE WEAK BOUNDARY LAYER
WINDS DESPITE FORECAST MIXING UP TO AROUND 850MB AND WIND DIRECTION
WILL BE VARIABLE. THIS IS CONVEYED THROUGH THE EVOLUTION OF THE
850MB TEMPERATURE FIELD. THE TEMPS WILL STAY MAINLY BETWEEN 5 AND 7
DEGREES C THROUGH THE DAY. MAX TEMPS LOOKED RELATIVELY SIMILAR
BETWEEN MAV AND MET WITH THE CORRESPONDING NUMERICAL MODEL BUFKIT
SOUNDINGS OF GFS AND NAM SHOWING MIXING JUST BELOW AND ABOVE 850MB
RESPECTIVELY. THERE ARE SIMILAR DIFFERENCES BETWEEN THE RUC AND SREF
SOUNDINGS AS WELL. MAX TEMP FORECAST GENERALLY IN THE UPPER 60S TO
LOWER 70S ACROSS MUCH OF THE FORECAST REGION WHICH WILL BE ABOUT 5
DEGREES BELOW NORMAL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
FOR TONIGHT...HIGH PRESSURE CONTINUES TO SLOWLY WEAKEN AND MOVE
SOUTH OF THE AREA AS THE UPPER LEVEL TROUGH CONTINUES TO WEAKEN
AND SHIFT WELL EAST OF THE AREA. THIS WILL SET UP A SOUTHWEST WIND
FLOW...WHICH WILL ALLOW FOR SLIGHTLY WARMER LOW TEMPS AND
ESSENTIALLY A MODERATION OF THE AIRMASS. THE 850MB TEMPS ACTUALLY
INCREASE SEVERAL DEGREES DURING THE NIGHT. CLEAR SKIES AND LIGHT
WINDS ESPECIALLY ACROSS THE INTERIOR HOWEVER WILL PROVIDE ANOTHER
GOOD NIGHT OF RADIATIONAL COOLING WHICH WILL OFFSET THE LIGHT
SOUTHWEST FLOW ADVECTING IN WARMER AIR. LOWS WILL BE RELATIVELY
SIMILAR TO THE PREVIOUS NIGHT FOR THE COASTAL AREAS AND URBAN
SECTIONS OF NEW YORK AND NEW JERSEY BUT A FEW DEGREES WARMER
ACROSS THE INTERIOR.
LOWS WERE A BLEND OF MET AND GMOS WITH GREATER WEIGHT FOR MET
GUIDANCE WHICH SHOWS A WIDER RANGE OF TEMPERATURES...WHICH FITS
WELL WITH GOOD RADIATIONAL COOLING.
FOR SATURDAY...HIGH PRESSURE CONTINUES TO WEAKEN AND PUSH SOUTH
OF THE REGION...WITH SOUTHWEST FLOW INCREASING. IN THE UPPER
LEVELS...A NORTHWEST FLOW WILL PREVAIL. TEMPERATURES WILL MAKE A
REBOUND...WITH 850 MB TEMPS INCREASING TO BETWEEN 12 AND 15
DEGREES C AND BOUNDARY LAYER WINDS INCREASE WITH VERTICAL MIXING
UP TO AROUND 900MB. INCREASING CLOUDS WILL START INFILTRATE THE
REGION FROM THE NORTH DURING THE AFTERNOON WELL UPSTREAM OF A
DEEPER SHORTWAVE MOVING INTO ONTARIO. THE HIGHS WERE A BLEND OF
MET AND MAV WITH GREATER WEIGHT TOWARDS THE MET GUIDANCE WHICH
SHOWS GREATER WARMTH ACROSS THE INTERIOR AND COOLER VALUES ALONG
THE COAST. AGAIN...THIS IS SHOWING GREATER RANGE. THIS TIME IT IS
BECAUSE OF THE DOWNSLOPE ACROSS INTERIOR AND MARINE INFLUENCE
ALONG THE COASTAL AREAS. THESE HIGHS WILL BE PRETTY CLOSE TO
NORMAL VALUES.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
MODELS STILL CLOSELY AGREE ON IDEA OF AN UPPER RIDGE OVER THE PLAINS
STATES AND TROUGH FROM THE MID ATLANTIC INTO EASTERN CANADA TO
START. A VIGOROUS SHORTWAVE WILL DIVE INTO THE BASE OF THE TROUGH ON
SUNDAY...DRIVING A COLD FRONT THROUGH. THIS FRONT WILL BE FOLLOWED
BY A GUSTY NW-N FLOW AS HIGH PRESSURE BUILDS QUICKLY...AND AFTER A
DAY OF NEAR AVG TEMPS ON SUNDAY...A BRIEF COOLER SPELL WILL FOLLOW
FOR SUNDAY NIGHT INTO MON...WITH TEMPS A FEW DEG BELOW AVG.
LOW TEMPS BY MON MORNING COULD APPROACH 40 IN THE COLDEST INTERIOR
VALLEYS AS THE HIGH BUILDS QUICKLY OVERHEAD.
AS THE UPPER TROUGH LIFTS NE WELL INTO NE CANADA...FLOW ALOFT WILL
BECOME MORE ZONAL...ALLOWING THE UPPER HIGH TO BUILD E-WD TO THE MID
ATLC AND SE COASTS AND A WARM FRONT TO PASS WELL TO OUR NORTH ON
TUE. TEMPS SHOULD SLOWLY WARM DURING MID WEEK...RISING TO SLIGHTLY
ABOVE AVG LEVELS WED AND THU. MULTIPLE SHORTWAVES EMBEDDED IN THE
FLOW SHOULD THEN CARVE OUT A NEW ERN TROUGH LATE THIS WEEK...
BRINGING ANOTHER COLD FRONT TOWARD THE AREA LATE IN THE WEEK.
TIMING OF THE FRONT STILL IN QUESTION...WHILE 00Z GFS/ECMWF ARE IN
AGREEMENT ON FROPA BY EARLY THU MORNING...THE 05/12Z ECMWF IDEA OF A
DEEPER UPPER TROUGH AND SLOWER TIMING MAY STILL BE PLAUSIBLE AND
HAVE DELAYED FRONTAL APPROACH UNTIL DAYTIME THU...AND FROPA UNTIL
THU NIGHT...WITH SHOWERS AND POSSIBLE TSTMS.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE WILL REMAIN OVER THE TERMINALS TODAY.
VFR THRU THE TAF PERIOD.
LIGHT NORTH TO NORTH-NORTHEAST WINDS ARE EXPECTED THROUGH 12Z.
WINDS THEN VEER TO THE NORTHEAST EARLY TODAY. WINDS THEN WEAKEN AND
SHIFT TO THE SOUTH LATE IN THE AFTERNOON AND TONIGHT.
A WEAK SEA BREEZE IS POSSIBLE ALONG THE IMMEDIATE SOUTH COASTAL
AIRPORTS. AWAY FROM THE COAST...EXPECT LIGHT AND VARIABLE WINDS.
...NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP://WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: HIGH CONFIDENCE VFR FORECAST. WIND SHIFT
EXPECTED DURING THE AFTERNOON. TIMING MAY BE OFF BY AN HOUR OR TWO.
KLGA FCSTER COMMENTS: HIGH CONFIDENCE VFR FORECAST. WIND SHIFT
EXPECTED DURING THE AFTERNOON. TIMING MAY BE OFF BY AN HOUR OR TWO.
KEWR FCSTER COMMENTS: HIGH CONFIDENCE VFR FORECAST. WIND SHIFT
EXPECTED DURING THE AFTERNOON. TIMING MAY BE OFF BY AN HOUR OR TWO.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: HIGH CONFIDENCE VFR FORECAST. WINDS BECOME
LIGHT AND VARIABLE DURING THE AFTERNOON. TIMING MAY BE OFF BY AN
HOUR OR TWO.
KHPN FCSTER COMMENTS: HIGH CONFIDENCE VFR FORECAST. WINDS BECOME
LIGHT AND VARIABLE DURING THE AFTERNOON. TIMING MAY BE OFF BY AN
HOUR OR TWO.
KISP FCSTER COMMENTS: HIGH CONFIDENCE VFR FORECAST. WINDS BECOME
LIGHT AND VARIABLE DURING THE AFTERNOON. TIMING MAY BE OFF BY AN
HOUR OR TWO.
OUTLOOK FOR 06Z SAT THROUGH MON...
.FRI NIGHT-SATURDAY NIGHT...VFR.
.SUNDAY...ISOLATED SHOWERS WITH BRIEF MVFR CONDITIONS POSSIBLE.
.SUNDAY NIGHT-TUESDAY...VFR.
&&
.MARINE...
SUB SCA CONDITIONS EXPECTED THROUGH SATURDAY. COLD AIR ADVECTION
OVER THE WARMER WATERS WILL KEEP GUSTS TO 20 KT INTO THIS MORNING
WITH A LOW CHANCE OF ANY 25 KT GUSTS ON THE OCEAN. HOWEVER...WIND
GUSTS WILL THEN SUBSIDE LATE THIS MORNING AND AFTERNOON AS A HIGH
PRESSURE CENTER TO THE WEST MOVES CLOSER TO THE AREA. THE
NORTHERLY WIND FLOW WILL WEAKEN AND BECOME MORE VARIABLE IN
DIRECTION...BEFORE TURNING MORE SOUTHWESTERLY TONIGHT. WINDS WILL
PICK UP MORE ON SATURDAY TO AROUND 10-15 KT IN THE AFTERNOON. SEAS
WILL STAY MAINLY BETWEEN 2 TO 3 FT ON THE OCEAN THROUGH SATURDAY.
SW FLOW AHEAD OF A COLD FRONT ON SUNDAY COULD BUILD THE OCEAN SEAS
OFF EASTERN LONG ISLAND TO 5 FT. POST-FRONTAL FLOW AS STRONG HIGH
PRESSURE BUILDS QUICKLY IN SHOULD GUST TO 25-30 ON THE OCEAN AND THE
ERN SOUND/BAYS SUNDAY NIGHT AND PERHAPS INTO PART OF MON
MORNING...WITH MAX OCEAN SEAS 6 FT DURING THAT TIME.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH THE MIDDLE OF
NEXT WEEK.
&&
.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/JM
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...GOODMAN
AVIATION...BC
MARINE...GOODMAN/JM
HYDROLOGY...GOODMAN/JM
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
402 AM EDT FRI SEP 6 2013
.SYNOPSIS...
CANADIAN HIGH PRESSURE WEAKENS AND SETTLES DIRECTLY OVER THE
REGION TODAY BEFORE SHIFTING SOUTH OF THE AREA THIS AFTERNOON
THROUGH SATURDAY NIGHT. A COLD FRONT WILL PASS THROUGH ON
SUNDAY...FOLLOWED BY HIGH PRESSURE FROM SUNDAY NIGHT THROUGH
WEDNESDAY. A COLD FRONT WILL APPROACH ON THURSDAY...AND PASS
THROUGH THURSDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
RADIATIONAL COOLING GOING INTO THE EARLY MORNING HOURS WILL ALLOW THE
TEMPERATURES TO DROP WELL INTO THE 40S AND 50S FOR MOST LOCATIONS
WITH A CONTINUED DRYING AIRMASS. WINDS WILL ALSO LOWER AS THE
INFLUENCE OF HIGH PRESSURE IS MORE FELT AS IT DRAWS CLOSER TO THE
AREA.
HIGH PRESSURE WEAKENS AND SETTLES DIRECTLY OVER THE REGION. A
BROAD WEAK UPPER LEVEL TROUGH MOVES ACROSS THE REGION WHICH WILL
BRING SOME CLOUDS BUT THINKING THAT THE SUBSIDENCE IS THE GREATER
FACTOR HERE WITH A MOSTLY SUNNY SKY PREVAILING. THE CENTER OF
HIGH PRESSURE WILL TREND SOUTH OF THE REGION BY THE LATE
AFTERNOON. A WEAK PRESSURE GRADIENT WILL ENABLE FOR LIGHT WINDS
AND THE SYNOPTIC FLOW WILL ENABLE FOR A WEAK SEA BREEZE LATE IN
THE AFTERNOON BUT TEMPERATURES ARE FORECAST TO BE ONLY A FEW
DEGREES ABOVE SEA SURFACE TEMPERATURES.
THE AIRMASS WILL BE SLOW TO MODERATE WITH THE WEAK BOUNDARY LAYER
WINDS DESPITE FORECAST MIXING UP TO AROUND 850MB AND WIND DIRECTION
WILL BE VARIABLE. THIS IS CONVEYED THROUGH THE EVOLUTION OF THE
850MB TEMPERATURE FIELD. THE TEMPS WILL STAY MAINLY BETWEEN 5 AND 7
DEGREES C THROUGH THE DAY. MAX TEMPS LOOKED RELATIVELY SIMILAR
BETWEEN MAV AND MET WITH THE CORRESPONDING NUMERICAL MODEL BUFKIT
SOUNDINGS OF GFS AND NAM SHOWING MIXING JUST BELOW AND ABOVE 850MB
RESPECTIVELY. THERE ARE SIMILAR DIFFERENCES BETWEEN THE RUC AND SREF
SOUNDINGS AS WELL. MAX TEMP FORECAST GENERALLY IN THE UPPER 60S TO
LOWER 70S ACROSS MUCH OF THE FORECAST REGION WHICH WILL BE ABOUT 5
DEGREES BELOW NORMAL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
FOR TONIGHT...HIGH PRESSURE CONTINUES TO SLOWLY WEAKEN AND MOVE
SOUTH OF THE AREA AS THE UPPER LEVEL TROUGH CONTINUES TO WEAKEN
AND SHIFT WELL EAST OF THE AREA. THIS WILL SET UP A SOUTHWEST WIND
FLOW...WHICH WILL ALLOW FOR SLIGHTLY WARMER LOW TEMPS AND
ESSENTIALLY A MODERATION OF THE AIRMASS. THE 850MB TEMPS ACTUALLY
INCREASE SEVERAL DEGREES DURING THE NIGHT. CLEAR SKIES AND LIGHT
WINDS ESPECIALLY ACROSS THE INTERIOR HOWEVER WILL PROVIDE ANOTHER
GOOD NIGHT OF RADIATIONAL COOLING WHICH WILL OFFSET THE LIGHT
SOUTHWEST FLOW ADVECTING IN WARMER AIR. LOWS WILL BE RELATIVELY
SIMILAR TO THE PREVIOUS NIGHT FOR THE COASTAL AREAS AND URBAN
SECTIONS OF NEW YORK AND NEW JERSEY BUT A FEW DEGREES WARMER
ACROSS THE INTERIOR.
LOWS WERE A BLEND OF MET AND GMOS WITH GREATER WEIGHT FOR MET
GUIDANCE WHICH SHOWS A WIDER RANGE OF TEMPERATURES...WHICH FITS
WELL WITH GOOD RADIATIONAL COOLING.
FOR SATURDAY...HIGH PRESSURE CONTINUES TO WEAKEN AND PUSH SOUTH
OF THE REGION...WITH SOUTHWEST FLOW INCREASING. IN THE UPPER
LEVELS...A NORTHWEST FLOW WILL PREVAIL. TEMPERATURES WILL MAKE A
REBOUND...WITH 850 MB TEMPS INCREASING TO BETWEEN 12 AND 15
DEGREES C AND BOUNDARY LAYER WINDS INCREASE WITH VERTICAL MIXING
UP TO AROUND 900MB. INCREASING CLOUDS WILL START INFILTRATE THE
REGION FROM THE NORTH DURING THE AFTERNOON WELL UPSTREAM OF A
DEEPER SHORTWAVE MOVING INTO ONTARIO. THE HIGHS WERE A BLEND OF
MET AND MAV WITH GREATER WEIGHT TOWARDS THE MET GUIDANCE WHICH
SHOWS GREATER WARMTH ACROSS THE INTERIOR AND COOLER VALUES ALONG
THE COAST. AGAIN...THIS IS SHOWING GREATER RANGE. THIS TIME IT IS
BECAUSE OF THE DOWNSLOPE ACROSS INTERIOR AND MARINE INFLUENCE
ALONG THE COASTAL AREAS. THESE HIGHS WILL BE PRETTY CLOSE TO
NORMAL VALUES.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
MODELS STILL CLOSELY AGREE ON IDEA OF AN UPPER RIDGE OVER THE PLAINS
STATES AND TROUGH FROM THE MID ATLANTIC INTO EASTERN CANADA TO
START. A VIGOROUS SHORTWAVE WILL DIVE INTO THE BASE OF THE TROUGH ON
SUNDAY...DRIVING A COLD FRONT THROUGH. THIS FRONT WILL BE FOLLOWED
BY A GUSTY NW-N FLOW AS HIGH PRESSURE BUILDS QUICKLY...AND AFTER A
DAY OF NEAR AVG TEMPS ON SUNDAY...A BRIEF COOLER SPELL WILL FOLLOW
FOR SUNDAY NIGHT INTO MON...WITH TEMPS A FEW DEG BELOW AVG.
LOW TEMPS BY MON MORNING COULD APPROACH 40 IN THE COLDEST INTERIOR
VALLEYS AS THE HIGH BUILDS QUICKLY OVERHEAD.
AS THE UPPER TROUGH LIFTS NE WELL INTO NE CANADA...FLOW ALOFT WILL
BECOME MORE ZONAL...ALLOWING THE UPPER HIGH TO BUILD E-WD TO THE MID
ATLC AND SE COASTS AND A WARM FRONT TO PASS WELL TO OUR NORTH ON
TUE. TEMPS SHOULD SLOWLY WARM DURING MID WEEK...RISING TO SLIGHTLY
ABOVE AVG LEVELS WED AND THU. MULTIPLE SHORTWAVES EMBEDDED IN THE
FLOW SHOULD THEN CARVE OUT A NEW ERN TROUGH LATE THIS WEEK...
BRINGING ANOTHER COLD FRONT TOWARD THE AREA LATE IN THE WEEK.
TIMING OF THE FRONT STILL IN QUESTION...WHILE 00Z GFS/ECMWF ARE IN
AGREEMENT ON FROPA BY EARLY THU MORNING...THE 05/12Z ECMWF IDEA OF A
DEEPER UPPER TROUGH AND SLOWER TIMING MAY STILL BE PLAUSIBLE AND
HAVE DELAYED FRONTAL APPROACH UNTIL DAYTIME THU...AND FROPA UNTIL
THU NIGHT...WITH SHOWERS AND POSSIBLE TSTMS.
&&
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE WILL REMAIN OVER THE TERMINALS TODAY.
VFR THRU THE TAF PERIOD.
LIGHT NORTH TO NORTH-NORTHEAST WINDS ARE EXPECTED THROUGH 12Z.
WINDS THEN VEER TO THE NORTHEAST EARLY FRIDAY. WINDS THEN WEAKEN AND
SHIFT TO THE SOUTH LATE FRIDAY INTO FRIDAY NIGHT.
A WEAK SEA BREEZE IS POSSIBLE ALONG THE IMMEDIATE SOUTH COASTAL
AIRPORTS. AWAY FROM THE COAST...EXPECT LIGHT AND VARIABLE WINDS.
OUTLOOK FOR 06Z SAT THROUGH MON...
.FRI NIGHT-SATURDAY NIGHT...VFR.
.SUNDAY...ISOLATED SHOWERS WITH BRIEF MVFR CONDITIONS POSSIBLE.
.SUNDAY NIGHT-TUESDAY...VFR.
&&
.MARINE...
SUB SCA CONDITIONS EXPECTED THROUGH SATURDAY. COLD AIR ADVECTION
OVER THE WARMER WATERS WILL KEEP GUSTS TO 20 KT INTO THIS MORNING
WITH A LOW CHANCE OF ANY 25 KT GUSTS ON THE OCEAN. HOWEVER...WIND
GUSTS WILL THEN SUBSIDE LATE THIS MORNING AND AFTERNOON AS A HIGH
PRESSURE CENTER TO THE WEST MOVES CLOSER TO THE AREA. THE
NORTHERLY WIND FLOW WILL WEAKEN AND BECOME MORE VARIABLE IN
DIRECTION...BEFORE TURNING MORE SOUTHWESTERLY TONIGHT. WINDS WILL
PICK UP MORE ON SATURDAY TO AROUND 10-15 KT IN THE AFTERNOON. SEAS
WILL STAY MAINLY BETWEEN 2 TO 3 FT ON THE OCEAN THROUGH SATURDAY.
SW FLOW AHEAD OF A COLD FRONT ON SUNDAY COULD BUILD THE OCEAN SEAS
OFF EASTERN LONG ISLAND TO 5 FT. POST-FRONTAL FLOW AS STRONG HIGH
PRESSURE BUILDS QUICKLY IN SHOULD GUST TO 25-30 ON THE OCEAN AND THE
ERN SOUND/BAYS SUNDAY NIGHT AND PERHAPS INTO PART OF MON
MORNING...WITH MAX OCEAN SEAS 6 FT DURING THAT TIME.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH THE MIDDLE OF
NEXT WEEK.
&&
.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/JM
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...GOODMAN
AVIATION...BC
MARINE...GOODMAN/JM
HYDROLOGY...GOODMAN/JM
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
201 AM EDT FRI SEP 6 2013
.SYNOPSIS...
CANADIAN HIGH PRESSURE WEAKENS AND SETTLES DIRECTLY OVER THE
REGION TODAY BEFORE SHIFTING SOUTH OF THE AREA THIS AFTERNOON
THROUGH SATURDAY NIGHT. A COLD FRONT MOVES ACROSS THE REGION ON
SUNDAY...FOLLOWED BY ANOTHER AREA OF HIGH PRESSURE FOR THE START
OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
SLIGHT ADJUSTMENTS FOR TEMPS AND DEWPOINTS WITH OTHERWISE NO
REMARKABLE CHANGES MADE TO THE FORECAST. THE WINDS HAVE STAYED UP
FOR SOME LOCATIONS...PARTICULARLY ACROSS THE COASTAL LOCATIONS
WHICH IS WHERE TEMPS WERE INCREASED SLIGHTLY. THE WIND HAS ACTED
TO MITIGATE RADIATIONAL COOLING.
MOSTLY CLEAR FOR THE REST OF THE NIGHT WITH A COOL CANADIAN
AIRMASS PROVIDING THE TRI-STATE AREA WITH BELOW NORMAL LOW
TEMPERATURES. MIN TEMPS GENERALLY IN THE UPPER 30S TO LOWER 40S
ACROSS THE INTERIOR WITH UPPER 40S TO UPPER 50S THE MIN TEMP RANGE
FOR COASTAL AREAS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
FOR FRIDAY...HIGH PRESSURE WEAKENS AND SETTLES DIRECTLY OVER THE
REGION. A BROAD WEAK UPPER LEVEL TROUGH MOVES ACROSS THE REGION.
THE CENTER OF HIGH PRESSURE WILL TREND SOUTH OF THE REGION BY THE
LATE AFTERNOON. A WEAK PRESSURE GRADIENT WILL ENABLE FOR LIGHT
WINDS AND THE SYNOPTIC FLOW WILL ENABLE FOR A WEAK SEA BREEZE LATE
IN THE AFTERNOON BUT TEMPERATURES ARE FORECAST TO BE ONLY A FEW
DEGREES ABOVE SEA SURFACE TEMPERATURES.
THE AIRMASS WILL BE SLOW TO MODERATE WITH THE WEAK BOUNDARY LAYER
WINDS DESPITE FORECAST MIXING UP TO AROUND 850MB AND WIND DIRECTION
WILL BE VARIABLE. THIS IS CONVEYED THROUGH THE EVOLUTION OF THE
850MB TEMPERATURE FIELD. THE TEMPS WILL STAY MAINLY BETWEEN 5 AND 7
DEGREES C THROUGH THE DAY. MAX TEMPS LOOKED RELATIVELY SIMILAR
BETWEEN MAV AND MET WITH THE CORRESPONDING NUMERICAL MODEL BUFKIT
SOUNDINGS OF GFS AND NAM SHOWING MIXING JUST BELOW AND ABOVE 850MB
RESPECTIVELY. THERE ARE SIMILAR DIFFERENCES BETWEEN THE RUC AND SREF
SOUNDINGS AS WELL. MAX TEMP FORECAST GENERALLY IN THE UPPER 60S TO
LOWER 70S ACROSS MUCH OF THE FORECAST REGION WHICH WILL BE ABOUT 5
DEGREES BELOW NORMAL.
FOR FRIDAY NIGHT...HIGH PRESSURE CONTINUES TO SLOWLY WEAKEN AND
MOVE SOUTH OF THE AREA AS THE UPPER LEVEL TROUGH CONTINUES TO
WEAKEN AND SHIFT WELL EAST OF THE AREA. THIS WILL SET UP A
SOUTHWEST WIND FLOW...WHICH WILL ALLOW FOR SLIGHTLY WARMER LOW
TEMPS AND ESSENTIALLY A MODERATION OF THE AIRMASS. THE 850MB TEMPS
ACTUALLY INCREASE SEVERAL DEGREES DURING THE NIGHT. CLEAR SKIES
AND LIGHT WINDS ESPECIALLY ACROSS THE INTERIOR HOWEVER WILL
PROVIDE ANOTHER GOOD NIGHT OF RADIATIONAL COOLING WHICH WILL
OFFSET THE LIGHT SOUTHWEST FLOW ADVECTING IN WARMER AIR.
FOR SATURDAY...HIGH PRESSURE CONTINUES TO WEAKEN AND PUSH SOUTH
OF THE REGION...WITH SOUTHWEST FLOW INCREASING. IN THE UPPER
LEVELS...A NORTHWEST FLOW WILL PREVAIL. TEMPERATURES WILL MAKE A
REBOUND...WITH 850 MB TEMPS INCREASING TO BETWEEN 12 AND 15
DEGREES C AND BOUNDARY LAYER WINDS INCREASE WITH VERTICAL MIXING
UP TO AROUND 930 TO 900MB.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
MODELS IN DECENT AGREEMENT WITH WEAK MEAN UPPER TROUGHING FOR THE
WEEKEND INTO EARLY NEXT WEEK GIVING WAY TO ZONAL TO SLIGHTLY RIDGED
FLOW FOR MID WEEK...BEFORE A STRONGER TROUGH APPROACHES FOR THE END
OF THE WEEK.
FAIR CONDITIONS WITH SEASONABLE TEMPS (UPPER 70S/LOWER 80S) THIS
WEEKEND AS HIGH PRESSURE WEAKENS AND SINKS SE OF THE REGION.
A SHORTWAVE DIGS INTO THE NORTHEAST ON SUNDAY AND THEN EAST SUNDAY
NIGHT...WITH AN ASSOCIATED COLD FRONTAL PASSAGE ON SUN. BEST FORCING
LOOKS TO BE NORTH OF THE REGION...AND WITH LACKING
INSTABILITY...ONLY EXPECTING ISOLATED TO SCATTERED SHOWER ACTIVITY
WITH FRONTAL PASSAGE ON SUNDAY (MAINLY NORTHERN ZONES). BEHIND THE
FRONT...A BRIEF SHOT OF COOL CANADIAN AIR EXPECTED FOR SUNDAY NIGHT
INTO MONDAY.
THEN A GRADUAL MODERATION TO SEASONABLE TO SLIGHTLY ABOVE SEASONABLE
CONDITIONS AND MORE HUMIDITY FOR MID WEEK AS CANADIAN HIGH PRESSURE
SINKS SOUTH OF THE REGION.
MODELS IN DECENT AGREEMENT WITH A STRONGER DIGGING TROUGH
APPROACHING WED INTO THU...WITH AN ASSOCIATED SLOW MOVING FRONTAL
SYSTEM APPROACHING THE REGION. THIS WILL BRING A GRADUALLY
INCREASING POTENTIAL FOR SHRA/TSRA ACTIVITY WED AFT/EVE...AND MORE SO
THU/THU NIGHT.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE WILL REMAIN OVER THE TERMINALS TODAY.
VFR THRU THE TAF PERIOD.
LIGHT NORTH TO NORTH-NORTHEAST WINDS ARE EXPECTED THROUGH 12Z.
WINDS THEN VEER TO THE NORTHEAST EARLY FRIDAY. WINDS THEN WEAKEN AND
SHIFT TO THE SOUTH LATE FRIDAY INTO FRIDAY NIGHT.
A WEAK SEA BREEZE IS POSSIBLE ALONG THE IMMEDIATE SOUTH COASTAL
AIRPORTS. AWAY FROM THE COAST...EXPECT LIGHT AND VARIABLE WINDS.
OUTLOOK FOR 06Z SAT THROUGH MON...
.FRI NIGHT-SATURDAY NIGHT...VFR.
.SUNDAY...ISOLATED SHOWERS WITH BRIEF MVFR CONDITIONS POSSIBLE.
.SUNDAY NIGHT-TUESDAY...VFR.
&&
.MARINE...
COLD AIR ADVECTION OVER THE WARMER WATERS WILL KEEP GUSTS TO 20 KT
FOR THE REST OF THE OVERNIGHT.
WIND GUSTS SUBSIDE INTO EARLY THIS MORNING AS A HIGH PRESSURE
CENTER TO THE WEST APPROACHES. THE NORTHERLY WIND FLOW WILL WEAKEN
AND MORE VARIABLE IN DIRECTION...BEFORE TURNING MORE SOUTHWESTERLY
TONIGHT.
GENERALLY SUB SCA CONDS THIS WEEKEND THROUGH NEXT WEEK. A COLD
FRONTAL PASSAGE SUNDAY NIGHT MAY HAVE SOME WIND GUSTS APPROACHING
25 KT.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH THE MIDDLE OF
NEXT WEEK.
&&
.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...JM/JC/NV
NEAR TERM...JM/JC
SHORT TERM...JM
LONG TERM...NV
AVIATION...BC
MARINE...JM/JC/NV
HYDROLOGY...JC/NV
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS MIAMI FL
1013 PM EDT SAT SEP 7 2013
.UPDATE...
LATEST SURFACE ANALYSIS SHOWS WEAK CONVERGENCE BOUNDARY ACROSS THE AREA
WHICH WAS THE MAIN FOCUS OF CONVECTION EARLIER MAINLY AROUND THE LAKE
OKEECHOBEE REGION. ACTIVITY HAS STEADILY DECREASED OVER THE PAST FEW
HOURS. 00Z SNDG AND AIRCRAFT DATA SHOW LIGHT LOW LEVEL EASTERLY FLOW
WITH CONSENSUS BETWEEN HRRR AND OTHER HIGH RES LOCAL MODELS BEING BEST
CHANCES OF OVERNIGHT SCATTERED ACTIVITY WILL LIKELY BE ATLANTIC WATERS
DUE TO INTERACTION BETWEEN AFOREMENTIONED BOUNDARY, THE LOW LEVEL FLOW,
AND A LIGHT OFFSHORE DRAINAGE FLOW ALONG THE EAST COAST. THERE IS ALSO
A CHANCE OF SUCH ACTIVITY ACROSS THE GULF WATERS BUT THE CHANCE IS LESS
DUE TO LACK OF OPPOSING LOW LEVEL AND DRAINAGE FLOWS. PRESENCE OF BOUNDARY,
VERY LIGHT LOW LEVEL WINDS, CALM AT THE SURFACE, HIGH ANTECEDENT MOISTURE,
AND DECREASING CLOUDS OVERNIGHT WILL LIKELY RESULT IN PATCHY GROUND
FOG ACROSS PORTIONS OF THE INTERIOR. FORECASTS HAVE ALL BEEN UPDATED
ACCORDINGLY.
&&
.PREV DISCUSSION... /ISSUED 746 PM EDT SAT SEP 7 2013/
AVIATION...
OUTSIDE OF SOME LINGERING LIGHT TO MODERATE RAIN WELL INLAND OF
THE TAF SITES THIS EVENING...CONDITIONS REMAIN QUIET WITH VFR
PREVAILING. THIS IS EXPECTED TO PERSIST THROUGH THE NIGHT AND INTO
SUNDAY. SIMILAR TO THIS MORNING...A FEW SHOWERS AND STORMS
SPREADING ASHORE ALONG THE EAST COAST WILL REMAIN POSSIBLE...WHICH
COULD IMPACT THE EAST COAST TERMINALS. THE LOW-LEVEL FLOW UNDER
10 KFT IS FORECAST TO REMAIN LIGHT THROUGH THE DAY SUNDAY...WHICH
WILL MOST LIKELY TRANSLATE TO SLOW MOVING STORMS. AS A
RESULT...WILL INCLUDE VCTS FROM 12Z ON FOR THE EAST COAST SITES
DUE TO THE POTENTIAL MORNING ACTIVITY AND VERY LITTLE STORM MOTION
EXPECTED. THE LATEST MODEL REFLECTIVITIES ARE MAINLY INDICATING
ISOLATED COVERAGE THROUGH SUNDAY.
PREV DISCUSSION... /ISSUED 244 PM EDT SAT SEP 7 2013/
SHORT TERM...
A TROUGH OF LOW PRESSURE OVER CENTRAL FLORIDA WILL CONTINUE TO
MOVE SLOWLY SOUTH TO LAKE OKEECHOBEE BY THIS EVENING...AND REMAIN
NEARLY STATIONARY TONIGHT INTO SUNDAY. THIS WILL KEEP A VERY LIGHT
NORTHEAST STEERING FLOW OVER SOUTH FLORIDA THIS AFTERNOON...BEFORE
GOING CLOSE TO NO STEERING FLOW TONIGHT INTO SUNDAY.
SO THE SHOWERS AND THUNDERSTORMS OVER THE NORTHERN AREAS OF SOUTH
FLORIDA EARLY THIS AFTERNOON WILL DRIFT TO THE SOUTHWEST THROUGH
THE AFTERNOON HOURS BEFORE DISSIPATING THIS EVENING. THESE SHOWERS
AND THUNDERSTORMS WILL ALSO LEAVE AN OUTFLOW BOUNDARY OVER THE
EAST COAST METRO AREAS TONIGHT WHICH COULD HELP TO GENERATE SOME
SHOWERS AND EVEN A FEW STORMS LATE TONIGHT INTO EARLY SUNDAY
MORNING. THEREFORE...THE POPS WILL REMAIN IN THE SCATTERED TO
LIKELY RANGE FOR THIS AFTERNOON OVER THE NORTHERN AREAS TAPERING
DOWN TO LOW END SCATTERED OVER THE SOUTHERN AREAS. THE POPS WILL
THEN DROP TO A SLIGHT 10 PERCENT FOR OVER MOST OF THE AREA FOR
LATE TONIGHT...EXCEPT 20 TO 30 PERCENT OVER THE EAST COAST METRO
AREAS.
WITH NO STEERING FLOW ON SUNDAY OVER SOUTH FLORIDA...THE SHOWERS
AND THUNDERSTORMS WILL MOVE VERY SLOWLY INLAND AS THE WEST AND
EAST COAST SEA BREEZES PUSHES INLAND SLOWLY. SO WILL UP THE POPS
OVER THE AREA FOR SUNDAY TO SCATTERED FOR THE METRO AREAS TO
LIKELY OVER THE INTERIOR AREAS.
THERE COULD ALSO BE SOME FOG OVER THE INTERIOR AND WEST COAST
METRO AREAS LATE TONIGHT AND AGAIN LATE SUNDAY NIGHT...AS THE
WINDS WILL BE CALM ALONG WITH THE LOW LEVEL MOISTURE IN PLACE. SO
WILL ADDED PATCHY FOG FOR THE INTERIOR AND WEST COAST METRO AREAS
FOR LATE TONIGHT AND AGAIN LATE SUNDAY NIGHT.
THE TROUGH OF LOW PRESSURE OVER LAKE OKEECHOBEE WILL THEN WASH OUT
ON MONDAY...AS HIGH PRESSURE STARTS TO BUILD BACK INTO CENTRAL
FLORIDA FROM THE WESTERN ATLANTIC WATERS. THIS WILL ALLOW FOR THE
STEERING FLOW TO BECOME A LITTLE BIT MORE EASTERLY ON MONDAY...AND
ALLOW EAST COAST SEA BREEZE TO PUSH INLAND A LITTLE BIT QUICKER.
SO THE BEST COVERAGE OF SHOWERS AND THUNDERSTORMS ON MONDAY WILL
BE MORE OVER THE INTERIOR AND WEST COAST METRO AREAS.
LONG TERM...
THE RIDGE OF HIGH PRESSURE WILL CONTINUE TO BUILD INTO CENTRAL
FLORIDA MIDDLE TO END OF NEXT WEEK DEEPENING THE EASTERLY WIND FLOW
OVER SOUTH FLORIDA. SO THE BEST AREAS THAT WILL SEE THE SCATTERED
SHOWERS AND THUNDERSTORMS SHOULD BE OVER THE INTERIOR AND WEST
COAST METRO AREAS EACH DAY.
AVIATION...
A WEAK TROUGH HAS ENHANCED THE INSTABILITY OVER SOUTH FLORIDA,
BRINGING NUMEROUS CONVECTIVE SHOWERS AND THUNDERSTORMS. THIS HAS
MADE FOR A TRICKY AVIATION FORECAST. FOR NOW, HAVE KEPT MOST OF
THE ACTIVITY IN THE NORTHERN AREAS, NEAR KPBI AND KFXE, THEN BRING
IT A LITTLE FURTHER SOUTH MID AFTERNOON. ALSO, THE GULF SHOULD
BEGIN TO DEVELOP CONVECTION NEAR KAPF IN THE NEXT COUPLE OF HOURS.
MODELS ARE INDICATING THAT THIS MORNINGS ACTIVITY MAY INHIBIT
CONVECTION FURTHER SOUTH, AT KMIA AND KTMB. SO FOR NOW, JUST HAVE
VCSH AT THOSE SITES. HOWEVER, CONDITIONS COULD CHANGE AND EVEN
THOSE SITES MAY NEED VCTS ADDED THIS AFTERNOON. CONVECTION ALONG
THE ATLANTIC COAST SHOULD MOVE OFF INTO THE INTERIOR PORTIONS,
AWAY FORM THE TAF SITES, AROUND 00Z. TOMORROW COULD SEE ANOTHER
ROUND OF AFTERNOON CONVECTION.
MARINE...
THE WINDS WILL BE NORTHEAST AT 10 KNOTS OR LESS OVER ALL OF THE
LOCAL WATERS OF SOUTH FLORIDA THROUGH MONDAY...BEFORE SWINGING TO
A EASTERLY DIRECTION AND INCREASING TO AROUND 15 KNOTS MIDDLE OF
NEXT WEEK. THIS WILL ALLOW FOR THE SEAS TO REMAIN AT OR BELOW 2
FEET IN BOTH THE ATLANTIC AND GULF WATERS OF SOUTH FLORIDA THROUGH
MONDAY...BEFORE SLOWLY INCREASING TO 2 TO 4 FEET IN THE ATLANTIC
WATERS OF SOUTH FLORIDA BY MIDDLE OF NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 73 88 75 88 / 20 50 30 30
FORT LAUDERDALE 76 88 77 88 / 20 40 20 30
MIAMI 75 89 76 89 / 20 50 30 40
NAPLES 72 90 73 92 / 30 40 20 40
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...52/PS
AVIATION/RADAR...85/AG
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
300 PM EDT FRI SEP 6 2013
...STRONG TO POTENTIALLY SEVERE STORMS POSSIBLE LATER THIS AFTERNOON
AND EVENING...
.SHORT TERM...
STRONG TSTMS HAVE BEEN ONGOING ALONG THE SPACE COAST THIS AFTERNOON
WITH A FEW MORE STORMS CURRENTLY OVER PORTIONS OF CITRUS AND
HERNANDO COUNTIES. GROWING INCREASINGLY CONCERNED OVER POTENTIAL OF
STRONG TO SEVERE TSTMS OVER PORTIONS OF THE FORECAST AREA. A
MODERATELY UNSTABLE AIRMASS EXISTS ACROSS THE FLORIDA PENINSULA THIS
AFTERNOON WITH MLCAPE VALUES OF 2000-3000 J/KG. THIS COMBINED WITH A
VERY MOIST BOUNDARY LAYER...AS EVIDENT ON THE MORNING KTBW RAOB
SHOULD ALLOW FOR THE POTENTIAL OF STRONG TO SEVERE TSTM DEVELOPMENT.
EXCESSIVE LIGHTNING...DAMAGING WINDS AND SOME HAIL WILL BE POSSIBLE
ALONG WITH VERY HEAVY RAINFALL. LATEST HRRR MODEL RUN SEEMS TO HAVE
A GRASP ON THE CURRENT CONVECTIVE ACTIVITY OVER THE PENINSULA. IT
SUGGESTS THAT THE BULK OF THE TSTMS CURRENTLY OVER ORANGE...LAKE AND
SEMINOLE COUNTIES WILL GRADUALLY MOVE INTO THE CWA OVER THE NEXT
HOUR OR SO. THE HRRR GUIDANCE SUGGEST THAT A SOMEWHAT LINEAR BAND OF
TSTMS WILL MOVE INTO INTERIOR SECTIONS OF THE AREA AROUND 21-22Z.
THE TAMPA BAY METRO AREA WILL LIKELY SEE ITS BEST CHANCE OF TSTM
ACTIVITY AROUND 23Z AND STORMS SHOULD BEGIN TO EXIT THE COAST AROUND
1-2Z THIS EVENING WITH LINGERING SHOWERS POSSIBLE OVER LAND AREAS
INTO THE EARLY OVERNIGHT HOURS.
SOMEWHAT DRIER AIR WILL MOVE INTO THE AREA TOMORROW WHICH COULD
SERVE AS LIMITING FACTOR FOR SHOWER AND TSTM COVERAGE UNTIL A TAD
LATER INTO THE AFTERNOON. NORTHERN ZONES WILL SEE THE DRIER AIR
FIRST AND BECAUSE OF THIS...LOWER RAIN CHANCES ARE FORECAST FOR THE
NATURE COAST NORTHWARD. STILL FEEL ENOUGH MOISTURE WILL BE IN PLACE
FROM TAMPA BAY SOUTH TO KEEP AROUND 40 POPS IN PLACE.
ON SUNDAY THE DRY AIR BECOMES WELL ESTABLISHED OVER MOST OF THE
REGION. MODELS STILL SHOW SOME POTENTIAL FOR SEA BREEZE INITIATED
STORMS...BUT THE OVERALL COVERAGE SHOULD BE QUITE A BIT LOWER THAN
TODAY AND SATURDAY WITH HIGHEST RAIN CHANCES DOWN SOUTH.
.LONG TERM (MONDAY THROUGH NEXT THURSDAY)...
LONG TERM PERIOD WILL BEGIN NEXT MONDAY WITH A PATTERN DOMINATED BY
LARGE SCALE UPPER RIDGING CENTERED OVER THE SE CONUS. RESIDUAL
ENERGY / WEAK TROUGHING LOOKS TO LINGER FROM OFF THE CAROLINA COAST
SOUTH AND SOUTHWEST TO THE SOUTHERN PORTION OF THE FLORIDA
PENINSULA. WEAK SUPPRESSION FROM THE UPPER RIDGE ALONG WITH THE
ADVECTION OF DRIER AIR DOWN FROM THE NORTH AND NORTHEAST AROUND THE
SYNOPTIC CIRCULATION LOOKS TO BRING SOME LESS FAVORABLE ATMOSPHERIC
CONDITIONS FOR DEEP CONVECTION TO PORTION OF THE AREA DURING THE
FIRST HALF OF THE WORK WEEK. BOTH THE GFS/ECMWF AGREE ON THE DRY AIR
BECOMING ENTRENCHED OVER THE NORTHERN HALF OF THE FORECAST
AREA...HOWEVER THE GFS IS MORE DRAMATIC WITH THIS DRYING...AND ALSO
MORE EXPANSIVE WITH THE DRIER MID-LEVEL AIR TO THE SOUTH.
EITHER WAY...A DECREASE IN THE OVERALL COVERAGE OF SHOWERS AND
STORMS FROM WHAT IS FORECAST OVER THE WEEKEND LOOKS LIKELY. BEST
CHANCES FOR SCATTERED AFTERNOON/EVENING STORMS MONDAY THROUGH
WEDNESDAY EXISTS SOUTH OF I-4...AND ESPECIALLY FROM PUNTA GORDA
SOUTHWARD...WHERE THE MORE "FAVORABLE" MOISTURE PROFILE WILL BE
COINCIDENT WITH EASTERLY LOW LEVEL FLOW TO FOCUS SEA-BREEZE
CONVERGENCE. EVEN STILL...ONLY GOING WITH 30-40% RAIN CHANCES FOR
THESE SOUTHERN ZONES...AND LESSER 20-30% RAIN CHANCES FOR THE
CENTRAL AND NATURE COAST ZONES. WITH THE UPPER RIDGE NEARBY...AND
THE POTENTIAL FOR LESS CONVECTIVE COVERAGE...DAYTIME TEMPS SHOULD
AVERAGE OUT A BIT ABOVE NORMAL.
DURING THE LAST COUPLE DAYS OF THE FORECAST PERIOD...THERE IS SOME
INDICATIONS IN THE GLOBAL GUIDANCE OF A SLOW RETURN OF DEEP MOISTURE
FROM THE EAST AND SOUTHEAST. ONCE AGAIN...THE GFS IS THE MOST
STUBBORN TO HOLD ON TO THE DRIER AIR (ESPECIALLY FROM TAMPA
NORTHWARD)...WHILE THE ECMWF RETURNS THE ENTIRE REGION TO A MORE
FAVORABLE COLUMN FOR DEEP CONVECTION BY FRIDAY. MID/UPPER LEVEL
MOISTURE FIELDS CAN BE SOMEWHAT QUESTIONABLE IN NWP GUIDANCE AT THE
LONGER RANGES...AND CERTAINLY WOULD NOT WANT TO "HANG MY HAT" ON ANY
ONE MODEL SOLUTION. WILL BLEND THE MORE RELIABLE SOLUTION...WHICH
SUGGESTS CHANCE 30-40% POPS FOR BOTH THURSDAY AND FRIDAY. MORE
MOISTURE SUCH AS THE ECMWF ADVERTISES WOULD LEAD TO HIGHER POPS BY
FRIDAY...AND LESS FAVORABLE CONDITIONS AS THE GFS ADVERTISES WOULD
LEAD TO LOWER POPS...ESPECIALLY FOR THE NATURE COAST ZONES.
&&
.AVIATION...
VFR CONDITIONS CURRENTLY PREVAIL ACROSS WEST-CENTRAL AND SOUTHWEST
FLORIDA WITH VCTS AT ALL TERMINALS THROUGH 01Z. I HAVE INCLUDED A
TEMPO GROUP FOR BRIEF MVFR/IFR CEILINGS AND VISIBILITIES AT ALL
TERMINAL SITES BETWEEN 06/21Z AND 06/24Z AS SCATTERED SHOWERS AND
STORMS DEVELOP OVER THE REGION. WINDS WILL BE VARIABLE IN VICINITY
OF THUNDERSTORMS WITH POSSIBLE STRONG GUSTS NEAR 40 KNOTS. STORMS
WILL DIMINISH BY 07/01Z...LEAVING PREVAILING VFR CONDITIONS ONCE
AGAIN UNDER A SCT-BKN HIGH LEVEL CIRRUS CANOPY.
&&
.MARINE...
HIGH PRESSURE CONTINUES TO PROVIDE EASTERLY FLOW THROUGH INTO NEXT
WEEK OVER THE WATERS. SHOWERS AND THUNDERSTORMS ARE EXPECTED MOST
DAYS...WITH LATE AFTERNOON AND EVENING THUNDERSTORMS COMING FROM THE
EAST POTENTIALLY CREATING HIGHER WINDS AND WAVES FOR MARINERS.
OTHERWISE...THERE MIGHT BE SOME WINDS AND WAVES NEARING CAUTIONARY
CRITERIA EARLY NEXT WEEK DUE TO OVERNIGHT EASTERLY WIND SURGES.
&&
.FIRE WEATHER...NO SIGNIFICANT FIRE WEATHER PROBLEMS BUT STAGNANT
HIGH PRESSURE OVER THE REGION WILL FAVOR LIGHT WINDS AND LIGHT
TRANSPORT WINDS RESULTING IN LOW DISPERSIONS FOR THE NEXT COUPLE
OF DAYS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 76 92 74 90 / 30 30 20 30
FMY 75 92 74 92 / 40 40 30 40
GIF 74 94 71 93 / 20 30 10 20
SRQ 75 92 73 91 / 30 30 20 30
BKV 70 92 69 92 / 30 30 20 20
SPG 79 90 77 89 / 30 30 20 30
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...11/MCKAUGHAN
LONG TERM...14/MROCZKA
AVIATION...74/WYNN
MARINE...02/GARCIA
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
948 AM EDT FRI SEP 6 2013
.DISCUSSION...
...SOME STRONG STORMS EXPECTED ACROSS THE INTERIOR THIS AFTERNOON...
.UPDATE...UPR LVL TROUGH EXTENDS INTO FL AND THE ERN GULF WITH
BACKDOOR SFC FRONT EXPECTED TO MOVE INTO NE FL LATER TODAY. TAMPA
SOUNDING DATA AND GPS PWAT DATA ACROSS CENTRAL FL INDICATE ELEVATED
MOISTURE LVLS WITH PWATS 1.8-2.0 INCHES AND H5 TEMPS AROUND -8 DEG
C. FULL SUN MANY AREAS THIS MORNING SHOULD LEAD TO PLENTY OF CAPE
LATER TODAY FOR SCATTERED SHOWER/TSTM DEVELOPMENT. 4.5KM WRF FOR
SPC/LOCAL WRF RUNS AND HRRR INDICATED HIGHER COVERAGE OF SHOWERS AND
STORMS ACROSS INTERIOR SECTIONS LATER THIS AFTERNOON AND WILL BUMP
UP POPS TO 50 PCT FOR LAKE COUNTY AND THE KISSIMMEE RIVER BASIN
ACROSS WESTERN OSCEOLA AND WESTERN OKEECHOBEE COUNTIES. WILL KEEP
40 PCT FOR THE REMAINDER OF THE INTERIOR AND 20 PCT ALONG THE
IMMEDIATE COAST WHERE E COAST BREEZE WILL MOVE INLAND. HIGHS NEAR 90
ALONG THE COAST AND THE LOWER TO MID 90S INTERIOR. THERE COULD BE
SOME STRONGER STORMS BY LATE AFTERNOON OVER THE INTERIOR WITH
FREQUENT CLOUD TO GROUND LIGHTNINGS...DOWNBURST WINDS TO 50 MPH AND
LOCALLY HEAVY RAINFALL AMOUNTS OF 2-3 INCHES.
&&
.AVIATION...EXPECT INTERIOR TERMINALS TO HAVE HIGHEST TSRA CHCS FROM
KSFB-KMCO VCNTY WESTWARD LATER THIS AFTERNOON. WILL CONSIDER TEMPO
TSRA FOR SOME INTERIOR SITES BTWN 19Z-23Z.
&&
.MARINE...WIND CALM AT BUOY 41009 SINCE 6 AM WITH 1-2 FT SEAS AND AN
8 SECOND PERIOD. LITTLE CHANGE FOR AFTERNOON FCST.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
VOLKMER/SEDLOCK
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
158 PM EDT FRI SEP 6 2013
.PREV DISCUSSION...
UPDATE...
/ISSUED 1136 AM EDT FRI SEP 6 2013/
NO CHANGES PLANNED TO THE FORECAST AS ITS ON TRACK. SOMEWHAT
QUESTIONABLE ABOUT THE SLIGHT CHANCE POPS IN THE MOUNTAINS THIS
AFTERNOON AND HRRR ISNT SHOWING ANYTHING DEVELOPING THERE. WITH
POTENTIAL FOR OROGRAPHIC LIFT...WILL LEAVE THE SLIGHT CHANCE IN
THERE FOR NOW AND WATCH TRENDS AS WE MOVE INTO THE AFTERNOON.
11
SHORT TERM /TODAY THROUGH SATURDAY NIGHT/...
/ISSUED 401 AM EDT FRI SEP 6 2013/
RELATIVELY DRY WX PATTERN TO CONTINUE TODAY AND SATURDAY AS LARGE
UPPER RIDGE CENTERED OVER THE CENTRAL HIGH PLAINS BUILDS EAST...
VERY WEAK NW FLOW PERSISTS OVER THE REGION AND GENERAL LACK OF ANY
SHORT WAVES/FRONTS UPSTREAM IN WESTERLIES OVER GREAT LAKES STATES.
WEAK STATIONARY FRONT OVER SOUTH GA STILL HAVING TROUBLE DECIDING
WHAT TO DO. LOW LEVEL MOISTURE IS HIGHER THAN FCST THIS MORNING
BUT ABSOLUTELY NO SIGN OF PRECIP IN NEARLY ALL MODEL GUIDANCE FOR
TODAY. ONLY THE HIRES WINDOW NMM SHOWS ISOLATED TSRA. HAVE
LOWERED/ DROPPED POPS BUT KEPT THEM AROUND 20PCT IN FAR SOUTHERN
ZONES AND NE GA MOUNTAINS. AS WITH LAST FEW DAYS...ANY TSRA WILL
NOT BE TOO STRONG AND WELL BELOW SEVERE LEVELS. SBCAPE PROGGED
500-1000 J/KG OVER FAR SRN ZONES. NAM AGAIN HAS A BAD CASE OF THE
CRAZIES WITH LACK OF VERTICAL MIXING AND TOO MUCH LOW LEVEL
MOISTURE AND CAPE IN THE AFTERNOON.
IF ONE THINKS TODAYS FCST IS DRY...WAIT TIL SATURDAY WITH NO POPS
FCST. AIRMASS CONTINUES TO DRY. FORTUNATELY TEMPS TO REMAIN JUST
ABOVE NORMAL...WHICH IS NO TOO SHABBY THIS TIME OF YEAR.
SNELSON
LONG TERM /SUNDAY THROUGH THURSDAY/...
/ISSUED 401 AM EDT FRI SEP 6 2013/
UPPER TROUGH MOVING OFF THE NORTHEAST COAST AT THE START OF THE
PERIOD WITH NORTHWEST FLOW CONTINUING ALOFT FOR THE CWA. THIS
SHOULD PUSH ANOTHER WEAK BACK DOOR FRONT INTO THE AREA LATE SUNDAY
EARLY MONDAY. HAVE KEPT LOW POPS IN FOR THIS TIME FRAME BUT
FAVORED THE NORTHERN ZONES. UPPER RIDGE BUILDS EASTWARD INTO THE
FORECAST AREA THROUGH MID WEEK. AFTERNOON HEATING SHOULD BE ABLE
TO TRIGGER A FEW THUNDERSTORMS EACH DAY. BY THE END OF THE WEEK
ANOTHER UPPER TROUGH MOVING ACROSS NEW ENGLAND SHOULD PUSH ANOTHER
BACK DOOR FRONT INTO THE SOUTHERN APPALACHIANS. AN INCREASE IN
DEEPER MOISTURE SHOULD GIVE CHANCE POPS TO THE CWA...FAVORING THE
NORTHERN ZONES. WITH INCREASED THICKNESS ALOFT AFTERNOON MAX
TEMPERATURES SHOULD GENERALLY RANGE MID 80S TO LOW 90S.
41
&&
.AVIATION...
18Z UPDATE...
VFR CONDITIONS EXPECTED THROUGH THIS EVENING. CU FIELD HAS
DEVELOPED ACROSS CSG AND MCN AND WILL CONTINUE TO DEVELOP ACROSS
THE ATL AREA...BUT THESE LOWER CLOUDS WILL DIMINISH AROUND SUNSET.
MAY SEE MVFR CONDITIONS AT AHN AND MCN IN THE MORNING DUE TO FOG.
//ATL CONFIDENCE...18Z UPDATE...
HIGH CONFIDENCE ON ALL ELEMENTS.
11
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 89 66 88 69 / 10 0 5 5
ATLANTA 88 69 88 72 / 10 0 5 5
BLAIRSVILLE 83 61 83 65 / 20 5 10 5
CARTERSVILLE 89 65 88 68 / 10 5 5 5
COLUMBUS 92 70 90 72 / 10 5 5 5
GAINESVILLE 85 66 86 70 / 10 5 5 5
MACON 91 67 90 69 / 10 0 5 5
ROME 90 65 89 68 / 5 5 5 5
PEACHTREE CITY 89 65 88 67 / 10 0 5 5
VIDALIA 90 70 89 72 / 20 10 10 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...11
LONG TERM....01
AVIATION...11
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
1136 AM EDT FRI SEP 6 2013
.UPDATE...
NO CHANGES PLANNED TO THE FORECAST AS ITS ON TRACK. SOMEWHAT
QUESTIONABLE ABOUT THE SLIGHT CHANCE POPS IN THE MOUNTAINS THIS
AFTERNOON AND HRRR ISNT SHOWING ANYTHING DEVELOPING THERE. WITH
POTENTIAL FOR OROGRAPHIC LIFT...WILL LEAVE THE SLIGHT CHANCE IN
THERE FOR NOW AND WATCH TRENDS AS WE MOVE INTO THE AFTERNOON.
11
&&
.PREV DISCUSSION...
SHORT TERM /TODAY THROUGH SATURDAY NIGHT/...
/ISSUED 401 AM EDT FRI SEP 6 2013/
RELATIVELY DRY WX PATTERN TO CONTINUE TODAY AND SATURDAY AS LARGE
UPPER RIDGE CENTERED OVER THE CENTRAL HIGH PLAINS BUILDS EAST...
VERY WEAK NW FLOW PERSISTS OVER THE REGION AND GENERAL LACK OF ANY
SHORT WAVES/FRONTS UPSTREAM IN WESTERLIES OVER GREAT LAKES STATES.
WEAK STATIONARY FRONT OVER SOUTH GA STILL HAVING TROUBLE DECIDING
WHAT TO DO. LOW LEVEL MOISTURE IS HIGHER THAN FCST THIS MORNING
.BUT ABSOLUTELY NO SIGN OF PRECIP IN NEARLY ALL MODEL GUIDANCE
FOR TODAY. ONLY THE HIRES WINDOW NMM SHOWS ISOLATED TSRA. HAVE
LOWERED/ DROPPED POPS BUT KEPT THEM AROUND 20PCT IN FAR SOUTHERN
ZONES AND NE GA MOUNTAINS. AS WITH LAST FEW DAYS...ANY TSRA WILL
NOT BE TOO STRONG AND WELL BELOW SEVERE LEVELS. SBCAPE PROGGED
500-1000 J/KG OVER FAR SRN ZONES. NAM AGAIN HAS A BAD CASE OF THE
CRAZIES WITH LACK OF VERTICAL MIXING AND TOO MUCH LOW LEVEL
MOISTURE AND CAPE IN THE AFTERNOON.
IF ONE THINKS TODAYS FCST IS DRY...WAIT TIL SATURDAY WITH NO POPS
FCST. AIRMASS CONTINUES TO DRY. FORTUNATELY TEMPS TO REMAIN JUST
ABOVE NORMAL...WHICH IS NO TOO SHABBY THIS TIME OF YEAR.
SNELSON
LONG TERM /SUNDAY THROUGH THURSDAY/...
/ISSUED 401 AM EDT FRI SEP 6 2013/
UPPER TROUGH MOVING OFF THE NORTHEAST COAST AT THE START OF THE
PERIOD WITH NORTHWEST FLOW CONTINUING ALOFT FOR THE CWA. THIS
SHOULD PUSH ANOTHER WEAK BACK DOOR FRONT INTO THE AREA LATE SUNDAY
EARLY MONDAY. HAVE KEPT LOW POPS IN FOR THIS TIME FRAME BUT
FAVORED THE NORTHERN ZONES. UPPER RIDGE BUILDS EASTWARD INTO THE
FORECAST AREA THROUGH MID WEEK. AFTERNOON HEATING SHOULD BE ABLE
TO TRIGGER A FEW THUNDERSTORMS EACH DAY. BY THE END OF THE WEEK
ANOTHER UPPER TROUGH MOVING ACROSS NEW ENGLAND SHOULD PUSH ANOTHER
BACK DOOR FRONT INTO THE SOUTHERN APPALACHIANS. AN INCREASE IN
DEEPER MOISTURE SHOULD GIVE CHANCE POPS TO THE CWA...FAVORING THE
NORTHERN ZONES. WITH INCREASED THICKNESS ALOFT AFTERNOON MAX
TEMPERATURES SHOULD GENERALLY RANGE MID 80S TO LOW 90S.
41
AVIATION...
12Z UPDATE...
/ISSUED 733 AM EDT FRI SEP 6 2013/
STILL NOT EXPECTING ANY PRECIP OR IMPACTS TODAY. SFC WINDS HAVE
SWITCHED TO NORTHEAST AS EXPECTED. PATCHY MVFR FOG WILL BE LIFTING
BEFORE 14Z BUT WILL LIKELY REDEVELOP AFTER 06Z TONIGHT.
//ATL CONFIDENCE...12Z UPDATE...
HIGH CONFIDENCE ON ALL ELEMENTS.
SNELSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 89 66 88 69 / 10 5 10 5
ATLANTA 88 69 88 72 / 10 5 10 10
BLAIRSVILLE 83 61 83 65 / 20 10 10 5
CARTERSVILLE 89 65 88 68 / 10 5 10 5
COLUMBUS 92 70 90 72 / 10 5 10 5
GAINESVILLE 85 66 86 70 / 10 5 10 5
MACON 91 67 90 69 / 10 5 10 5
ROME 90 65 89 68 / 5 5 10 5
PEACHTREE CITY 89 65 88 67 / 10 5 10 5
VIDALIA 90 70 89 72 / 20 10 10 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...11
LONG TERM....01
AVIATION...11
AREA FORECAST DISCUSSION
NWS POCATELLO ID
154 PM MDT FRI SEP 6 2013
.DISCUSSION...THE SLOW MOVING UPPER LOW OVER THE PAC NW WAS OVER
CENTRAL WA THIS AFTN...AND WILL CONTINUE TO SLOWLY DRIFT E TO THE
ID PANHANDLE BY SUNDAY MORNING. THE SUBTROPICAL MOISTURE PLUME IS
BACKING A LITTLE TO THE WEST TODAY...WHICH WILL PULL THE THREAT OF
TSTMS BACK INTO THE SNAKE RIVER PLAIN ADJACENT TO THE SE HIGHLANDS
THRU THIS EVE. BOTH THE NAM AND HRRR MODELS ARE BOTH PICKING UP ON
THIS. THUNDERSTORMS WILL DECREASE IN COVERAGE LATE THIS EVENING. THE
CYCLE REPEATS ON SATURDAY...AS THE UPPER LOW ONLY MOVES SLIGHTLY
EASTWARD. BY SUNDAY...MOST OF THE SUBTROPICAL MOISTURE MOVES OFF
TO THE EAST...SO ONLY EXPECTING ISOLD TSTMS OVER THE MTNS.
FOR MON THRU WED...THE REGION WILL REMAIN DRY AND WARM AS UPPER
RIDGING BECOMES THE DOMINANT FEATURE. AS THE RIDGE MOVES OFF TO
THE EAST ON THU...SUBTROPICAL MOISTURE ONCE AGAIN HAS A PATH INTO
ID. AS A RESULT...HAVE INCREASED THE TSTM CHANCES FOR THU AND FRI.
HEDGES
&&
.AVIATION...MOISTURE AXIS SEEN ON WV ACROSS SOUTHEAST IDAHO. EXPECT
TO SEE CONVECTION FOCUS ALONG THIS AXIS. MODELS ARE SUGGESTING A
ROUND OF LATE AFTERNOON/EVENING THUNDERSTORMS. HRRR DEVELOPS
CONVECTION ALONG UTAH BORDER AND MOVES IT NORTHEASTWARD ACROSS
KBYI...KPIH AND KIDA. NAM IS HINTING AT SOME CONVECTIVE ACTIVITY IN
THE CENTRAL MOUNTAINS...BUT THERE REMAINS ENOUGH UNCERTAINTY WHEN
COMPARED TO HRRR/LOCAL WRF MODEL TO REMOVE VCTS MENTION AT KSUN
TERMINAL AND REPLACE WITH VCSH. MOISTURE AXIS STAYS OVER SOUTHEAST
IDAHO THROUGH TOMORROW. HAVE KEPT BKN CLOUD COVER THROUGH PERIOD
WITH VCSH STARTING AROUND MID-MORNING AT KPIH AND KIDA. HINSBERGER
&&
.FIRE WEATHER...THUNDERSTORMS WILL DEVELOP ACROSS A MOISTURE BAND
LOCATED ACROSS THE SOUTHEAST HIGHLANDS AND THE SNAKE RIVER PLAIN.
MODELS HINTING THAT THE STRONGEST CHANCES WILL BE DURING THE EVENING
HOURS. MOISTURE WILL REMAIN OVER THE SOUTHEAST HIGHLANDS THROUGH
TOMORROW AS AN UPPER LOW SLOWLY MAKES ITS WAY ACROSS THE PAC NW AND
FINALLY PUSHES OUT OF THE AREA SUNDAY EVENING. SIGNIFICANTLY DRIER
AIR WILL MOVE BACK INTO THE REGION DURING THE FIRST HALF OF NEXT
WEEK AS UPPER RIDGING BUILDS BACK INTO THE PAC NW. AFTER
WEDNESDAY...UPPER RIDGING SHIFTS EASTWARD OPENING UP THE MONSOONAL
FLOW ACROSS THE AREA. THUS WE SHOULD SEE AN INCREASE IN THUNDERSTORM
ACTIVITY TOWARDS THE LATTER HALF OF NEXT WEEK. HINSBERGER
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS POCATELLO ID
920 AM MDT FRI SEP 6 2013
.UPDATED DISCUSSION...MORNING WV SAT LOOP SHOWING A LITTLE BACKING
OF THE MONSOON PLUME. NAM AND HRRR MODELS ALSO SUGGESTING TSTMS
LATER THIS AFTN AND EARLY EVE MORE TO THE WEST THAN PREVIOUSLY
INDICATED. HAVE PUSHED THE HIGHER POPS FROM THE EASTERN HIGHLANDS
BACK WESTWARD TO THE ADJACENT SNAKE RIVER PLAIN AS A RESULT. STRONG
UPPER LEVEL FLOW SHOULD RESULT IN FASTER CELL MOVEMENT...THUS A
LOWER CHANCE FOR HEAVY RAINFALL. HEDGES
.SHORT TERM...TODAY THROUGH SUNDAY
UPPER LOW CONTINUES TO PUSH NORTHEAST TODAY INTO WASHINGTON STATE
WITH SOUTHERLY FLOW ALOFT CONTINUING TO PUSH MOISTURE INTO THE
REGION. A COLD FRONT WILL MOVE THROUGH EASTERN IDAHO ALSO AND
EXPECT SLIGHTLY COOLER TEMPERATURES TODAY. DO EXPECT ISOLATED TO
SCATTERED THUNDERSTORMS ONCE AGAIN WITH THE BEST CHANCE IN THE
EASTERN HIGHLANDS TODAY. UPPER LOW MAKES SLOW PROGRESSION EAST
THROUGH THE WEEKEND AND EXPECT AT LEAST SOME ISOLATED THUNDERSTORM
ACTIVITY TO CONTINUE THROUGH THE WEEKEND. EXPECT SOME CONTINUED
COOLING THROUGH SUNDAY BUT TEMPERATURES STILL REMAINING SLIGHTLY
ABOVE NORMAL.
GK
.LONG TERM...MONDAY THROUGH FRIDAY.
UPPER FLOW TURNS NORTHWESTERLY MONDAY AFTER UPPER TROF FINALLY
PUSHES EAST. EXPECT DRY CONDITIONS MONDAY AND TUESDAY. MODELS
RETURN TO SOUTHERLY FLOW LATE NEXT WEEK AND EUROPEAN HAS SOME
PRECIPITATION AS EARLY AS WEDNESDAY BUT HELD OFF ON GRIDS UNTIL
THURSDAY RETURNING TO CONVECTIVE ACTIVITY. MONDAY WILL BE THE
COOLEST DAY OF THE LONG TERM WITH NEAR NORMAL TEMPERATURES. EXPECT
ABOVE NORMAL CONDITIONS RETURNING TUESDAY.
GK
&&
.AVIATION...ALTHOUGH WE SHOULD SEE A BREAK IN THE NOCTURNAL
THUNDERSTORM ACTIVITY AT KSUN THIS MORNING...THE TERMINAL WILL
LIKELY SEE RENEWED ACTIVITY THIS AFTERNOON AS A LOW PRESSURE SYSTEM
LIFTS SLOWLY NORTH INTO WASHINGTON. KPIH AND KIDA MAY ALSO SEE VCTS
THIS AFTERNOON AS CONVECTION BUILDS ACROSS THE SE HIGHLANDS
ASSOCIATED WITH A BAND OF SUB-TROPICAL MOISTURE STILL ARCING NORTH
INTO THE REGION. ALL IN ALL...VFR CONDITIONS SHOULD PREVAIL. HUSTON
&&
.FIRE WEATHER...EARLY MORNING SATELLITE IMAGERY CONTINUED TO SHOW A
RIDGE OF HIGH PRESSURE ANCHORED OVER COLORADO AS A LOW PRESSURE
SYSTEM WAS LIFTING GRADUALLY NE ACROSS OREGON. THUNDERSTORM ACTIVITY
CONTINUED TO FIRE ACROSS THE CNTRL MOUNTAINS IN CLOSER PROXIMITY TO
THE CENTER OF THE LOW AND UPPER JET DYNAMICS. AS THE LOW DRIFTS
SLOWLY NORTH INTO WASHINGTON TODAY...THUNDERSTORMS WILL CONTINUE TO
DEVELOP ACROSS MAINLY THE CNTRL MOUNTAINS AND SE HIGHLANDS WHERE THE
BEST INSTABILITY...MOISTURE...AND DYNAMICAL FORCING RESIDE. THE LOW
EVENTUALLY LIFTS INTO SRN BRITISH COLUMBIA SATURDAY AS A
DRIER...MORE STABLE SW FLOW OVERSPREADS THE CNTRL MOUNTAINS AND
SUB-TROPICAL MOISTURE CONTINUES TO ARC NORTH ACROSS THE GREAT BASIN
INTO THE ERN HIGHLANDS SUPPORTING ONGOING THUNDERSTORM ACTIVITY
ALONG THE UTAH/WYOMING BORDER REGIONS. BY SUNDAY THE LOW DRIFTS
FURTHER EAST INTO ALBERTA AS THE FLOW ALOFT BECOMES MORE WESTERLY.
THE BEST CHANCE FOR SHOWERS IS EXPECTED ALONG THE MONTANA BORDER
CLOSER TO THE CORE OF THE LOW AND NEAR THE WYOMING BORDER WHERE
RESIDUAL SUB-TROPICAL MOISTURE LINGERS. BY MONDAY A DRY AND STABLE
NW FLOW TAKES HOLD WHILE AFTERNOON HIGHS BOTTOM OUT NEAR THEIR
NORMAL CLIMATOLOGICAL HIGHS FOR THIS TIME OF YEAR. A HIGH PRESSURE
RIDGE BUILDS INTO THE AREA BY MID-WEEK BRINGING WARMER TEMPERATURES
WHILE THE MODELS THROW A WILD-CARD INTO THE MIX AS A SUB-TROPICAL
STORM IS EVIDENT LIFTING NORTH ALONG THE SRN CALIFORNIA COAST. THIS
APPROACHING STORM MAY BRING A CHANCE OF AFTERNOON THUNDERSTORMS BACK
TO THE REGION AS EARLY AS THURSDAY. HUSTON
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1003 PM CDT SAT SEP 7 2013
.DISCUSSION...
748 PM CDT
FOR EVENING UPDATE...
HAVE MADE SOME SIGNIFICANT CHANGES TO LOWER POPS/DECREASE COVERAGE
OF SHOWER/THUNDERSTORM CHANCES THIS EVENING AND OVERNIGHT.
CONVECTION HAS STRUGGLED ACROSS THE CWA SINCE LATE THIS
AFTERNOON...LIKELY DUE TO WEAK CONVERGENCE AND RELATIVELY DRY LOW
LEVEL AIR MASS AND PERSISTENT CAP NOTED BETWEEN 800-850MB IN BOTH
ILX/DVN 00Z SOUNDINGS. COLD FRONT REMAINS NORTH/WEST OF THE AREA
AT 01Z...AND WILL SINK ACROSS THE AREA OVERNIGHT...THOUGH
DECREASING DIURNAL INSTABILITY WILL MOST LIKELY LIMIT POTENTIAL
FOR ADDITIONAL SIGNIFICANT SHOWER/THUNDERSTORM DEVELOPMENT
DESPITE HIGH-RES CONVECTIVE ALLOWING GUIDANCE CONTINUING TO
DEPICT POTENTIAL FOR MORE STORMS TO FORM. SPC/RAP MESOANALYSIS
INDICATES STRONGER INSTABILITY/WEAKER CAPPING REMAINS ACROSS
NORTHEAST IA...THUS HAVE MAINTAINED CHANCE POPS MAINLY ACROSS
WEST/SOUTH PARTS OF CWA SIMILAR TO EARLIER THINKING...WHILE
LOWERING TO ISOLATED OR NONE FARTHER EAST/NORTHEAST.
FRONT WILL SLIP IN LATE TONIGHT...WITH INCREASING NORTHEAST WINDS
BY MORNING AS SURFACE HIGH PRESSURE BUILDS SOUTHEAST ACROSS THE
LAKES.
RATZER
//PREV DISCUSSION...
SHORT TERM...TONIGHT THROUGH TUESDAY...
FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO
TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY.
THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER
CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH
FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS
DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST
ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS
ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST
GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING
THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING
COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS
VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN
AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL
MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD
INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING
INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE
POPS MAY BE TOO HIGH.
ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE
TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW
CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW
LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG
ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE
FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST
FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S
NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS
MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT
STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA
DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN
DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT
MAINTAINED A DRY FORECAST FOR NOW.
VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT
AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW
PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW
PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS
A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST
HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL
PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925
MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A
FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR
SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT
OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A
SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY.
GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S
AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR
MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL
BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA
BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL
PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER
CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING
GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD
ONLY IN THE LOW-MID 60S.
LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...
MAINTAINED BLENDED GUIDANCE FOR MID-HIGH CHANCE POPS TUESDAY
EVENING/NIGHT WITH COLD FRONT BUT IF FRONT SLOWS
FURTHER...INSTABILITY MAY WANE ENOUGH TO GREATLY LIMIT COVERAGE OF
SHRA/TSRA. THEN ON WEDNESDAY...THE FRONT WILL STILL BE DROPPING
SOUTHWARD...KEEPING A CHANCE FOR THUNDER GOING. AIR MASS WILL ONLY
BE MODESTLY COOLER INITIALLY. THEN A MUCH COOLER AIRMASS WILL
FINALLY ARRIVE THURSDAY INTO FRIDAY AS EASTERN NOAM TROUGH DEEPENS
AND BRUSHES OUR AREA WHILE STRONG CANADIAN HIGH PRESSURE SPREADS
SOUTHWARD. 850 MB THERMAL TROUGH LOOKS TO ARRIVE THURSDAY NIGHT INTO
FRIDAY...WITH MID TO HIGH SINGLE DIGITS AT 850 MB. SO AFTER A COOLER
BUT BASICALLY SEASONABLE THURSDAY...FRIDAY WILL BE A TASTE OF AUTUMN
WITH HIGHS ONLY IN THE LOW-MID 70S AWAY FROM LAKE MICHIGAN AND
MID-UPPER 60S ON THE LAKEFRONT. HEIGHT RISES WILL QUICKLY RETURN
SATURDAY SO TEMPERATURES WILL WARM SLIGHTLY.
RC
&&
.CLIMATE...
653 PM CDT
RECORD WARMTH FOR SEPTEMBER 10TH IS POSSIBLE ON TUESDAY:
CHICAGO:
RECORD HIGH: 95 (1983)
RECORD WARM LOW: 75 (1912)
ROCKFORD:
RECORD HIGH: 96 (1931)
RECORD WARM LOW: 70 (2000)
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* LGT/VRBL WINDS BECOMING NORTHEAST BY MIDNIGHT...AND INCREASING
OVERNIGHT WITH COLD FRONT PASSAGE.
* LOW END MVFR CIGS LIKELY DEVELOPING LATE TONIGHT/EARLY SUNDAY
MORNING.
* BREEZY EAST-NORTHEAST WINDS SUNDAY...GUSTS NEAR 20 KT PSBL.
RATZER
//DISCUSSION...UPDATED 00Z...
FAIRLY COMPLEX TERMINAL WEATHER LATE THIS AFTERNOON AND EARLY THIS
EVENING. CLUSTER OF THUNDERSTORMS WHICH PASSED SOUTHEAST ACROSS
LAKE MICHIGAN EARLIER HAD PUSHED AN OUTFLOW BOUNDARY TO ABOUT AN
ORD-MDW LINE...THOUGH BOUNDARY WAS DRIFTING BACK TO THE EAST-
NORTHEAST WITH WINDS BECOMING SOUTHERLY AGAIN AT 2330Z. SUBSIDENCE
IN THE WAKE OF THE AFOREMENTIONED THUNDERSTORM CLUSTER APPEARS TO
HAVE STIFLED ADDITIONAL CONVECTIVE DEVELOPMENT NEAR THE TERMINALS.
THE ACTUAL SURFACE COLD FRONTAL BOUNDARY REMAINS WELL NORTH OF THE
AREA EARLY THIS EVENING...STRETCHING ROUGHLY FROM MANITOWOC WI
SOUTHWEST TO A WEAK SURFACE LOW PRESSURE WAVE OVER SOUTHEAST IOWA.
WHILE WINDS HAVE RETURNED TO THE SOUTH ACROSS THE TERMINALS AT
THIS TIME...THE COMBINATION OF THE WEAKENING PRESSURE GRADIENT IN
THE VICINITY OF THE APPROACHING FRONTAL TROUGH AND A TREND TO
BECOME MORE SOUTH-SOUTHEAST AHEAD OF THE IOWA SFC LOW MAY RESULT
IN SOME VARIABILITY IN WIND DIRECTION UNTIL THE FRONT ACTUALLY
PASSES LATE THIS EVENING. FROPA SHOULD BE IN THE 04-06Z RANGE...
AFTER WHICH CONFIDENCE INCREASES IN NORTHEAST WINDS WHICH WILL
EVENTUALLY BECOME BREEZY/GUSTY OVERNIGHT AS CANADIAN HIGH PRESSURE
BUILDS SOUTHEAST ACROSS THE GREAT LAKES.
CURRENT EXPECTATION IS THAT WEAK CONVECTION SOUTH OF CHICAGO WILL
CONTINUE TO TRACK OFF TO THE SOUTHEAST THIS EVENING...WHILE SMALL
AREAS OF THUNDERSTORMS CLOSER TO THE FRONT IN IOWA/WISCONSIN WILL
DECAY BEFORE IMPACTING LOCAL TERMINALS OVERNIGHT. THE SHIFT TO
NORTHEAST WINDS AND COOLER AIR OFF THE LAKE BEHIND THE COLD FRONT
TONIGHT IS EXPECTED TO RESULT IN SOME LOWER CLOUD DEVELOPMENT...
WITH LOW MVFR CIGS INDICATED IN MODEL FORECASTS. THIS LOOKS TO BE
QUITE REASONABLE...THOUGH CONFIDENCE IN TIMING OF BOTH DEVELOPMENT
AND EVENTUAL LIFTING SUNDAY IS FAIRLY LOW.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE IN WIND TRENDS.
* HIGH CONFIDENCE IN MVFR CIGS DEVELOPING LATE TONIGHT...BUT
MEDIUM CONFIDENCE IN TIMING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY THROUGH TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE.
THURSDAY THROUGH FRIDAY...VFR.
RATZER
&&
.MARINE...
129 PM CDT
A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF
LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE
LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE
NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO
25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A
DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING
SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS
CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR
THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL
CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL
BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES
ARE EXPECTED.
THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST
SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER
GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A
CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS
SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE
EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF
ON EXTENDING THE ADVISORY INTO THIS PERIOD.
THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL
LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW
PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA.
LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP
ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM SUNDAY TO 11 PM
SUNDAY.
IN...BEACH HAZARDS STATEMENT...INZ001...4 AM SUNDAY TO 11 PM SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM
SUNDAY.
SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11
PM SUNDAY.
&&
$$
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
802 PM CDT SAT SEP 7 2013
.DISCUSSION...
748 PM CDT
FOR EVENING UPDATE...
HAVE MADE SOME SIGNIFICANT CHANGES TO LOWER POPS/DECREASE COVERAGE
OF SHOWER/THUNDERSTORM CHANCES THIS EVENING AND OVERNIGHT.
CONVECTION HAS STRUGGLED ACROSS THE CWA SINCE LATE THIS
AFTERNOON...LIKELY DUE TO WEAK CONVERGENCE AND RELATIVELY DRY LOW
LEVEL AIR MASS AND PERSISTENT CAP NOTED BETWEEN 800-850MB IN BOTH
ILX/DVN 00Z SOUNDINGS. COLD FRONT REMAINS NORTH/WEST OF THE AREA
AT 01Z...AND WILL SINK ACROSS THE AREA OVERNIGHT...THOUGH
DECREASING DIURNAL INSTABILITY WILL MOST LIKELY LIMIT POTENTIAL
FOR ADDITIONAL SIGNIFICANT SHOWER/THUNDERSTORM DEVELOPMENT
DESPITE HIGH-RES CONVECTIVE ALLOWING GUIDANCE CONTINUING TO
DEPICT POTENTIAL FOR MORE STORMS TO FORM. SPC/RAP MESOANALYSIS
INDICATES STRONGER INSTABILITY/WEAKER CAPPING REMAINS ACROSS
NORTHEAST IA...THUS HAVE MAINTAINED CHANCE POPS MAINLY ACROSS
WEST/SOUTH PARTS OF CWA SIMILAR TO EARLIER THINKING...WHILE
LOWERING TO ISOLATED OR NONE FARTHER EAST/NORTHEAST.
FRONT WILL SLIP IN LATE TONIGHT...WITH INCREASING NORTHEAST WINDS
BY MORNING AS SURFACE HIGH PRESSURE BUILDS SOUTHEAST ACROSS THE
LAKES.
RATZER
&&
.PREV DISCUSSION...
SHORT TERM...TONIGHT THROUGH TUESDAY...
FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO
TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY.
THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER
CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH
FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS
DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST
ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS
ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST
GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING
THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING
COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS
VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN
AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL
MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD
INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING
INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE
POPS MAY BE TOO HIGH.
ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE
TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW
CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW
LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG
ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE
FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST
FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S
NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS
MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT
STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA
DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN
DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT
MAINTAINED A DRY FORECAST FOR NOW.
VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT
AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW
PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW
PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS
A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST
HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL
PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925
MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A
FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR
SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT
OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A
SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY.
GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S
AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR
MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL
BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA
BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL
PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER
CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING
GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD
ONLY IN THE LOW-MID 60S.
LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...
MAINTAINED BLENDED GUIDANCE FOR MID-HIGH CHANCE POPS TUESDAY
EVENING/NIGHT WITH COLD FRONT BUT IF FRONT SLOWS
FURTHER...INSTABILITY MAY WANE ENOUGH TO GREATLY LIMIT COVERAGE OF
SHRA/TSRA. THEN ON WEDNESDAY...THE FRONT WILL STILL BE DROPPING
SOUTHWARD...KEEPING A CHANCE FOR THUNDER GOING. AIR MASS WILL ONLY
BE MODESTLY COOLER INITIALLY. THEN A MUCH COOLER AIRMASS WILL
FINALLY ARRIVE THURSDAY INTO FRIDAY AS EASTERN NOAM TROUGH DEEPENS
AND BRUSHES OUR AREA WHILE STRONG CANADIAN HIGH PRESSURE SPREADS
SOUTHWARD. 850 MB THERMAL TROUGH LOOKS TO ARRIVE THURSDAY NIGHT INTO
FRIDAY...WITH MID TO HIGH SINGLE DIGITS AT 850 MB. SO AFTER A COOLER
BUT BASICALLY SEASONABLE THURSDAY...FRIDAY WILL BE A TASTE OF AUTUMN
WITH HIGHS ONLY IN THE LOW-MID 70S AWAY FROM LAKE MICHIGAN AND
MID-UPPER 60S ON THE LAKEFRONT. HEIGHT RISES WILL QUICKLY RETURN
SATURDAY SO TEMPERATURES WILL WARM SLIGHTLY.
RC
&&
.CLIMATE...
653 PM CDT
RECORD WARMTH FOR SEPTEMBER 10TH IS POSSIBLE ON TUESDAY:
CHICAGO:
RECORD HIGH: 95 (1983)
RECORD WARM LOW: 75 (1912)
ROCKFORD:
RECORD HIGH: 96 (1931)
RECORD WARM LOW: 70 (2000)
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* LIGHT SOUTH WINDS MAY BE VARIABLE IN DIRECTION AT TIMES THIS
EVENING BEFORE BECOMING NORTHEAST LATE...AND INCREASING IN SPEED
FROM THE NORTHEAST OVERNIGHT.
* LOW MVFR CIGS LIKELY DEVELOPING LATE TONIGHT/EARLY SUNDAY
MORNING.
* BREEZY EAST-NORTHEAST WINDS SUNDAY.
RATZER
//DISCUSSION...UPDATED 00Z...
FAIRLY COMPLEX TERMINAL WEATHER LATE THIS AFTERNOON AND EARLY THIS
EVENING. CLUSTER OF THUNDERSTORMS WHICH PASSED SOUTHEAST ACROSS
LAKE MICHIGAN EARLIER HAD PUSHED AN OUTFLOW BOUNDARY TO ABOUT AN
ORD-MDW LINE...THOUGH BOUNDARY WAS DRIFTING BACK TO THE EAST-
NORTHEAST WITH WINDS BECOMING SOUTHERLY AGAIN AT 2330Z. SUBSIDENCE
IN THE WAKE OF THE AFOREMENTIONED THUNDERSTORM CLUSTER APPEARS TO
HAVE STIFLED ADDITIONAL CONVECTIVE DEVELOPMENT NEAR THE TERMINALS.
THE ACTUAL SURFACE COLD FRONTAL BOUNDARY REMAINS WELL NORTH OF THE
AREA EARLY THIS EVENING...STRETCHING ROUGHLY FROM MANITOWOC WI
SOUTHWEST TO A WEAK SURFACE LOW PRESSURE WAVE OVER SOUTHEAST IOWA.
WHILE WINDS HAVE RETURNED TO THE SOUTH ACROSS THE TERMINALS AT
THIS TIME...THE COMBINATION OF THE WEAKENING PRESSURE GRADIENT IN
THE VICINITY OF THE APPROACHING FRONTAL TROUGH AND A TREND TO
BECOME MORE SOUTH-SOUTHEAST AHEAD OF THE IOWA SFC LOW MAY RESULT
IN SOME VARIABILITY IN WIND DIRECTION UNTIL THE FRONT ACTUALLY
PASSES LATE THIS EVENING. FROPA SHOULD BE IN THE 04-06Z RANGE...
AFTER WHICH CONFIDENCE INCREASES IN NORTHEAST WINDS WHICH WILL
EVENTUALLY BECOME BREEZY/GUSTY OVERNIGHT AS CANADIAN HIGH PRESSURE
BUILDS SOUTHEAST ACROSS THE GREAT LAKES.
CURRENT EXPECTATION IS THAT WEAK CONVECTION SOUTH OF CHICAGO WILL
CONTINUE TO TRACK OFF TO THE SOUTHEAST THIS EVENING...WHILE SMALL
AREAS OF THUNDERSTORMS CLOSER TO THE FRONT IN IOWA/WISCONSIN WILL
DECAY BEFORE IMPACTING LOCAL TERMINALS OVERNIGHT. THE SHIFT TO
NORTHEAST WINDS AND COOLER AIR OFF THE LAKE BEHIND THE COLD FRONT
TONIGHT IS EXPECTED TO RESULT IN SOME LOWER CLOUD DEVELOPMENT...
WITH LOW MVFR CIGS INDICATED IN MODEL FORECASTS. THIS LOOKS TO BE
QUITE REASONABLE...THOUGH CONFIDENCE IN TIMING OF BOTH DEVELOPMENT
AND EVENTUAL LIFTING SUNDAY IS FAIRLY LOW.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* MEDIUM CONFIDENCE WITH WIND TRENDS THIS EVENING.
* MEDIUM-HIGH CONFIDENCE THAT ADDITIONAL TSRA WILL REMAIN WELL
WEST/SOUTH...OR WELL NORTH OF ORD/MDW THROUGH THIS EVENING.
* HIGH CONFIDENCE IN WIND FORECAST BEHIND COLD FRONT LATE TONIGHT
AND SUNDAY.
* MEDIUM TO HIGH CONFIDENCE IN MVFR CIGS DEVELOPING LATE TONIGHT
BUT LOW TO MEDIUM CONFIDENCE IN TIMING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY THROUGH TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE.
THURSDAY THROUGH FRIDAY...VFR.
RATZER
&&
.MARINE...
129 PM CDT
A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF
LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE
LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE
NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO
25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A
DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING
SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS
CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR
THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL
CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL
BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES
ARE EXPECTED.
THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST
SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER
GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A
CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS
SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE
EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF
ON EXTENDING THE ADVISORY INTO THIS PERIOD.
THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL
LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW
PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA.
LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP
ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM SUNDAY TO 11 PM
SUNDAY.
IN...BEACH HAZARDS STATEMENT...INZ001...4 AM SUNDAY TO 11 PM SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM
SUNDAY.
SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11
PM SUNDAY.
&&
$$
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
654 PM CDT SAT SEP 7 2013
.MESOSCALE DISCUSSION...
540 PM CDT
CONTINUING TO MONITOR SEVERE POTENTIAL INTO THIS EVENING.
INITIAL LEAD SHORT WAVE THAT SPARKED CONVECTION OVER LAKE MICHIGAN
AND AIDED DEVELOPMENT OF THUNDERSTORMS IMMEDIATELY BEHIND OUTFLOW
BOUNDARY/HYBRID LAKE BREEZE JUST INLAND FROM THE LAKE HAS
PROGRESSED OFF TO THE EAST WITH SUBSIDENCE IMMEDIATELY BEHIND IT.
ON ITS TAILS IS ANOTHER SHORT WAVE NOTED ON W/V CROSSING THE
MISSISSIPPI RIVER VALLEY. AT THE SAME TIME...SURFACE ANALYSIS
INDICATES FAIRLY ILL DEFINED COLD FRONT STRETCHING FROM NORTHERN
IOWA TO WEST CENTRAL WISCONSIN TO NEAR GREEN BAY.
THE PRESENCE OF MIDLEVEL SHORT WAVE HAS ALLOWED FOR AGITATED CU AND
SCATTERED TSRA OVER WESTERN PORTION OF CWA. MODERATE
INSTABILITY...EFFECTIVE SHEAR OF 35-40 KT AND MODERATELY STEEP LOW
LEVEL LAPSE RATES EXIST IN THIS AREA. STORMS SHOULD CONTINUE TO
FESTER IN CENTRAL/NORTH CENTRAL IL...WITH DEVELOPMENT POSSIBLY
FURTHER AIDED BY APPROACH OF COLD FRONT FROM NORTH. FARTHER
EAST...AFOREMENTIONED SUBSIDENCE BEHIND LEAD WAVE AND PRONOUNCED
CAPPING NOTED ON RECENT AIRCRAFT SOUNDINGS WILL HINDER TSTORM
DEVELOPMENT IN THE NEAR TERM. IN THE MORE FAVORED AREA IN
WEST/SOUTHWEST CWA...ROUGHLY COINCIDING WITH THE SPC SLIGHT RISK
OUTLINE...STEEP LOW LEVEL LAPSE RATES COULD SUPPORT A DAMAGING
WIND THREAT IN MORE INTENSE CORES AND ANY CELLS THAT ATTAIN
MIDLEVEL ROTATION IN PRESENCE OF MARGINALLY FAVORABLE DEEP SHEAR
COULD ALSO PRODUCE LOW END SEVERE HAIL. IN ADDITION...PRECIPITABLE
WATER VALUES AROUND 1.8 INCHES COULD ALSO RESULT IN LOCALLY VERY
HEAVY DOWNPOURS.
A CLUSTER OF THUNDERSTORMS HAS DEVELOPED IMMEDIATELY AHEAD OF COLD
FRONT NEAR GREEN BAY...BUT BY THE TIME IT APPROACHES OUR AREA FROM
THE NORTH...INSTABILITY WILL LIKELY HAVE WANED LENDING DOUBT TO
PERSISTENCE OF STRONG CONVECTION. OVERALL...PLENTY OF UNCERTAINTY
EXISTS REGARDING STORM COVERAGE EVEN IN MORE FAVORED AREA...SO
THE THREAT FOR SEVERE WEATHER APPEARS TO BE FAIRLY LIMITED.
RC
&&
.DISCUSSION...
SHORT TERM...TONIGHT THROUGH TUESDAY...
FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO
TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY.
THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER
CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH
FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS
DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST
ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS
ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST
GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING
THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING
COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS
VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN
AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL
MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD
INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING
INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE
POPS MAY BE TOO HIGH.
ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE
TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW
CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW
LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG
ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE
FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST
FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S
NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS
MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT
STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA
DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN
DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT
MAINTAINED A DRY FORECAST FOR NOW.
VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT
AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW
PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW
PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS
A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST
HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL
PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925
MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A
FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR
SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT
OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A
SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY.
GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S
AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR
MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL
BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA
BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL
PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER
CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING
GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD
ONLY IN THE LOW-MID 60S.
LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...
MAINTAINED BLENDED GUIDANCE FOR MID-HIGH CHANCE POPS TUESDAY
EVENING/NIGHT WITH COLD FRONT BUT IF FRONT SLOWS
FURTHER...INSTABILITY MAY WANE ENOUGH TO GREATLY LIMIT COVERAGE OF
SHRA/TSRA. THEN ON WEDNESDAY...THE FRONT WILL STILL BE DROPPING
SOUTHWARD...KEEPING A CHANCE FOR THUNDER GOING. AIR MASS WILL ONLY
BE MODESTLY COOLER INITIALLY. THEN A MUCH COOLER AIRMASS WILL
FINALLY ARRIVE THURSDAY INTO FRIDAY AS EASTERN NOAM TROUGH DEEPENS
AND BRUSHES OUR AREA WHILE STRONG CANADIAN HIGH PRESSURE SPREADS
SOUTHWARD. 850 MB THERMAL TROUGH LOOKS TO ARRIVE THURSDAY NIGHT INTO
FRIDAY...WITH MID TO HIGH SINGLE DIGITS AT 850 MB. SO AFTER A COOLER
BUT BASICALLY SEASONABLE THURSDAY...FRIDAY WILL BE A TASTE OF AUTUMN
WITH HIGHS ONLY IN THE LOW-MID 70S AWAY FROM LAKE MICHIGAN AND
MID-UPPER 60S ON THE LAKEFRONT. HEIGHT RISES WILL QUICKLY RETURN
SATURDAY SO TEMPERATURES WILL WARM SLIGHTLY.
RC
&&
.CLIMATE...
653 PM CDT
RECORD WARMTH FOR SEPTEMBER 10TH IS POSSIBLE ON TUESDAY:
CHICAGO:
RECORD HIGH: 95 (1983)
RECORD WARM LOW: 75 (1912)
ROCKFORD:
RECORD HIGH: 96 (1931)
RECORD WARM LOW: 70 (2000)
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* LIGHT SOUTH WINDS MAY BE VARIABLE IN DIRECTION AT TIMES THIS
EVENING BEFORE BECOMING NORTHEAST LATE...AND INCREASING IN SPEED
FROM THE NORTHEAST OVERNIGHT.
* LOW MVFR CIGS LIKELY DEVELOPING LATE TONIGHT/EARLY SUNDAY
MORNING.
* BREEZY EAST-NORTHEAST WINDS SUNDAY.
RATZER
//DISCUSSION...UPDATED 00Z...
FAIRLY COMPLEX TERMINAL WEATHER LATE THIS AFTERNOON AND EARLY THIS
EVENING. CLUSTER OF THUNDERSTORMS WHICH PASSED SOUTHEAST ACROSS
LAKE MICHIGAN EARLIER HAD PUSHED AN OUTFLOW BOUNDARY TO ABOUT AN
ORD-MDW LINE...THOUGH BOUNDARY WAS DRIFTING BACK TO THE EAST-
NORTHEAST WITH WINDS BECOMING SOUTHERLY AGAIN AT 2330Z. SUBSIDENCE
IN THE WAKE OF THE AFOREMENTIONED THUNDERSTORM CLUSTER APPEARS TO
HAVE STIFLED ADDITIONAL CONVECTIVE DEVELOPMENT NEAR THE TERMINALS.
THE ACTUAL SURFACE COLD FRONTAL BOUNDARY REMAINS WELL NORTH OF THE
AREA EARLY THIS EVENING...STRETCHING ROUGHLY FROM MANITOWOC WI
SOUTHWEST TO A WEAK SURFACE LOW PRESSURE WAVE OVER SOUTHEAST IOWA.
WHILE WINDS HAVE RETURNED TO THE SOUTH ACROSS THE TERMINALS AT
THIS TIME...THE COMBINATION OF THE WEAKENING PRESSURE GRADIENT IN
THE VICINITY OF THE APPROACHING FRONTAL TROUGH AND A TREND TO
BECOME MORE SOUTH-SOUTHEAST AHEAD OF THE IOWA SFC LOW MAY RESULT
IN SOME VARIABILITY IN WIND DIRECTION UNTIL THE FRONT ACTUALLY
PASSES LATE THIS EVENING. FROPA SHOULD BE IN THE 04-06Z RANGE...
AFTER WHICH CONFIDENCE INCREASES IN NORTHEAST WINDS WHICH WILL
EVENTUALLY BECOME BREEZY/GUSTY OVERNIGHT AS CANADIAN HIGH PRESSURE
BUILDS SOUTHEAST ACROSS THE GREAT LAKES.
CURRENT EXPECTATION IS THAT WEAK CONVECTION SOUTH OF CHICAGO WILL
CONTINUE TO TRACK OFF TO THE SOUTHEAST THIS EVENING...WHILE SMALL
AREAS OF THUNDERSTORMS CLOSER TO THE FRONT IN IOWA/WISCONSIN WILL
DECAY BEFORE IMPACTING LOCAL TERMINALS OVERNIGHT. THE SHIFT TO
NORTHEAST WINDS AND COOLER AIR OFF THE LAKE BEHIND THE COLD FRONT
TONIGHT IS EXPECTED TO RESULT IN SOME LOWER CLOUD DEVELOPMENT...
WITH LOW MVFR CIGS INDICATED IN MODEL FORECASTS. THIS LOOKS TO BE
QUITE REASONABLE...THOUGH CONFIDENCE IN TIMING OF BOTH DEVELOPMENT
AND EVENTUAL LIFTING SUNDAY IS FAIRLY LOW.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* MEDIUM CONFIDENCE WITH WIND TRENDS THIS EVENING.
* MEDIUM-HIGH CONFIDENCE THAT ADDITIONAL TSRA WILL REMAIN WELL
WEST/SOUTH...OR WELL NORTH OF ORD/MDW THROUGH THIS EVENING.
* HIGH CONFIDENCE IN WIND FORECAST BEHIND COLD FRONT LATE TONIGHT
AND SUNDAY.
* MEDIUM TO HIGH CONFIDENCE IN MVFR CIGS DEVELOPING LATE TONIGHT
BUT LOW TO MEDIUM CONFIDENCE IN TIMING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY THROUGH TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE.
THURSDAY THROUGH FRIDAY...VFR.
RATZER
&&
.MARINE...
129 PM CDT
A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF
LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE
LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE
NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO
25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A
DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING
SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS
CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR
THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL
CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL
BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES
ARE EXPECTED.
THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST
SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER
GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A
CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS
SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE
EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF
ON EXTENDING THE ADVISORY INTO THIS PERIOD.
THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL
LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW
PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA.
LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP
ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM SUNDAY TO 11 PM
SUNDAY.
IN...BEACH HAZARDS STATEMENT...INZ001...4 AM SUNDAY TO 11 PM SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM
SUNDAY.
SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11
PM SUNDAY.
&&
$$
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
544 PM CDT SAT SEP 7 2013
.MESOSCALE DISCUSSION...
540 PM CDT
CONTINUING TO MONITOR SEVERE POTENTIAL INTO THIS EVENING.
INITIAL LEAD SHORT WAVE THAT SPARKED CONVECTION OVER LAKE MICHIGAN
AND AIDED DEVELOPMENT OF THUNDERSTORMS IMMEDIATELY BEHIND OUTFLOW
BOUNDARY/HYBRID LAKE BREEZE JUST INLAND FROM THE LAKE HAS
PROGRESSED OFF TO THE EAST WITH SUBSIDENCE IMMEDIATELY BEHIND IT.
ON ITS TAILS IS ANOTHER SHORT WAVE NOTED ON W/V CROSSING THE
MISSISSIPPI RIVER VALLEY. AT THE SAME TIME...SURFACE ANALYSIS
INDICATES FAIRLY ILL DEFINED COLD FRONT STRETCHING FROM NORTHERN
IOWA TO WEST CENTRAL WISCONSIN TO NEAR GREEN BAY.
THE PRESENCE OF MIDLEVEL SHORT WAVE HAS ALLOWED FOR AGITATED CU AND
SCATTERED TSRA OVER WESTERN PORTION OF CWA. MODERATE
INSTABILITY...EFFECTIVE SHEAR OF 35-40 KT AND MODERATELY STEEP LOW
LEVEL LAPSE RATES EXIST IN THIS AREA. STORMS SHOULD CONTINUE TO
FESTER IN CENTRAL/NORTH CENTRAL IL...WITH DEVELOPMENT POSSIBLY
FURTHER AIDED BY APPROACH OF COLD FRONT FROM NORTH. FARTHER
EAST...AFOREMENTIONED SUBSIDENCE BEHIND LEAD WAVE AND PRONOUNCED
CAPPING NOTED ON RECENT AIRCRAFT SOUNDINGS WILL HINDER TSTORM
DEVELOPMENT IN THE NEAR TERM. IN THE MORE FAVORED AREA IN
WEST/SOUTHWEST CWA...ROUGHLY COINCIDING WITH THE SPC SLIGHT RISK
OUTLINE...STEEP LOW LEVEL LAPSE RATES COULD SUPPORT A DAMAGING
WIND THREAT IN MORE INTENSE CORES AND ANY CELLS THAT ATTAIN
MIDLEVEL ROTATION IN PRESENCE OF MARGINALLY FAVORABLE DEEP SHEAR
COULD ALSO PRODUCE LOW END SEVERE HAIL. IN ADDITION...PRECIPITABLE
WATER VALUES AROUND 1.8 INCHES COULD ALSO RESULT IN LOCALLY VERY
HEAVY DOWNPOURS.
A CLUSTER OF THUNDERSTORMS HAS DEVELOPED IMMEDIATELY AHEAD OF COLD
FRONT NEAR GREEN BAY...BUT BY THE TIME IT APPROACHES OUR AREA FROM
THE NORTH...INSTABILITY WILL LIKELY HAVE WANED LENDING DOUBT TO
PERSISTENCE OF STRONG CONVECTION. OVERALL...PLENTY OF UNCERTAINTY
EXISTS REGARDING STORM COVERAGE EVEN IN MORE FAVORED AREA...SO
THE THREAT FOR SEVERE WEATHER APPEARS TO BE FAIRLY LIMITED.
RC
&&
.DISCUSSION...
SHORT TERM...TONIGHT THROUGH TUESDAY...
FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO
TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY.
THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER
CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH
FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS
DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST
ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS
ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST
GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING
THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING
COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS
VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN
AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL
MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD
INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING
INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE
POPS MAY BE TOO HIGH.
ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE
TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW
CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW
LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG
ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE
FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST
FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S
NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS
MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT
STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA
DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN
DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT
MAINTAINED A DRY FORECAST FOR NOW.
VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT
AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW
PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW
PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS
A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST
HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL
PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925
MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A
FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR
SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT
OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A
SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY.
GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S
AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR
MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL
BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA
BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL
PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER
CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING
GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD
ONLY IN THE LOW-MID 60S.
LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...
MAINTAINED BLENDED GUIDANCE FOR MID-HIGH CHANCE POPS TUESDAY
EVENING/NIGHT WITH COLD FRONT BUT IF FRONT SLOWS
FURTHER...INSTABILITY MAY WANE ENOUGH TO GREATLY LIMIT COVERAGE OF
SHRA/TSRA. THEN ON WEDNESDAY...THE FRONT WILL STILL BE DROPPING
SOUTHWARD...KEEPING A CHANCE FOR THUNDER GOING. AIR MASS WILL ONLY
BE MODESTLY COOLER INITIALLY. THEN A MUCH COOLER AIRMASS WILL
FINALLY ARRIVE THURSDAY INTO FRIDAY AS EASTERN NOAM TROUGH DEEPENS
AND BRUSHES OUR AREA WHILE STRONG CANADIAN HIGH PRESSURE SPREADS
SOUTHWARD. 850 MB THERMAL TROUGH LOOKS TO ARRIVE THURSDAY NIGHT INTO
FRIDAY...WITH MID TO HIGH SINGLE DIGITS AT 850 MB. SO AFTER A COOLER
BUT BASICALLY SEASONABLE THURSDAY...FRIDAY WILL BE A TASTE OF AUTUMN
WITH HIGHS ONLY IN THE LOW-MID 70S AWAY FROM LAKE MICHIGAN AND
MID-UPPER 60S ON THE LAKEFRONT. HEIGHT RISES WILL QUICKLY RETURN
SATURDAY SO TEMPERATURES WILL WARM SLIGHTLY.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* OUTFLOW BOUNDARY HAS STALLED OVER ORD...PUSHED JUST WEST OF MDW.
WIND LIKELY TO STAY LIGHT SOUTH NOW AT ORD...EAST BECOMING SOUTH
AGAIN AT MDW.
* WEAKENING SHRA/TSRA IN VCNTY NEXT 1-2 HOURS.
* EVENTUAL WIND SHIFT TO NORTHEAST LATE THIS EVENING WITH COLD
FRONT.
* LOW MVFR CIGS LIKELY DEVELOPING LATE TONIGHT/EARLY SUNDAY
MORNING.
RATZER
//DISCUSSION...UPDATED 18Z...
SYNOPSIS...WARM MOIST SOUTHWEST FLOW AHEAD OF A WEAK COLD FRONT...
WHICH EXTENDED FROM NORTHERN LAKE MICHIGAN ACROSS CENTRAL WI TO NW
IA THIS AFTERNOON. THE FRONT WILL MOVE THROUGH NORTHERN ILLINOIS
THIS EVENING. HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT
LAKES SUNDAY WITH STRONG NORTHEAST WINDS DEVELOPING.
THUNDERSTORM CLUSTER OVER SOUTHEAST WI MOVING SOUTHEAST BUT NEW
DEVELOPMENT AHEAD AND WEST OF MAIN CLUSTER OF STORMS MAY CLIP FAR
NORTHEAST ILLINOIS MID TO LATE AFTERNOON. WEAK INSTABILITY AND
SOMEWHAT OF A CAP WILL LIMIT DEVELOPMENT AND EXPECT MOST OF THIS
ACTIVITY TO DRIFT ACROSS LAKE MICHIGAN. HAVE ADDED A VCTS FOR LOW
CHANCE OF THUNDER NEAR ORD THIS AFTERNOON.
INSTABILITY WILL CONTINUE TO BUILD THROUGH THE AFTERNOON. CONVERGENCE
ALONG THE FRONT WILL BE FAIRLY WEAK BUT SHOULD BE SUFFICIENT FOR
SCATTERED THUNDERSTORMS AHEAD OF AND ALONG THE COLD FRONT EARLY
THIS EVENING. THUNDERSTORMS SHOULD DIMINISH AND SHIFT SOUTH LATE
THIS EVENING. BEHIND THE FRONT WINDS WILL BECOME NORTHEAST. WINDS
WILL INCREASE TOWARDS MORNING. MODEL GUIDANCE SUGGESTING LOW MVFR
AND POSSIBLY EVEN IFR CIGS WILL DEVELOP BEHIND THE COLD FRONT. LOW
CIGS SHOULD LIFT BY AFTERNOON. EXPECT NORTHEAST WINDS 12 TO 20 KTS
THROUGH THE DAY SUNDAY.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* MEDIUM CONFIDENCE WITH WIND TRENDS THIS EVENING.
* MEDIUM CONFIDENCE THAT ADDITIONAL TSRA WILL REMAIN WELL
WEST/SOUTH OF ORD/MDW.
* HIGH CONFIDENCE IN WIND FORECAST BEHIND COLD FRONT LATE TONIGHT
AND SUNDAY.
* MEDIUM TO HIGH CONFIDENCE IN MVFR CIGS DEVELOPING LATE TONIGHT
BUT LOW TO MEDIUM CONFIDENCE IN TIMING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT THROUGH TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE.
WEDNESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
129 PM CDT
A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF
LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE
LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE
NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO
25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A
DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING
SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS
CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR
THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL
CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL
BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES
ARE EXPECTED.
THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST
SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER
GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A
CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS
SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE
EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF
ON EXTENDING THE ADVISORY INTO THIS PERIOD.
THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL
LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW
PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA.
LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP
ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM SUNDAY TO 11 PM
SUNDAY.
IN...BEACH HAZARDS STATEMENT...INZ001...4 AM SUNDAY TO 11 PM SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM
SUNDAY.
SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11
PM SUNDAY.
&&
$$
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
518 PM CDT SAT SEP 7 2013
.DISCUSSION...
SHORT TERM...TONIGHT THROUGH TUESDAY...
FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO
TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY.
THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER
CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH
FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS
DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST
ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS
ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST
GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING
THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING
COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS
VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN
AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL
MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD
INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING
INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE
POPS MAY BE TOO HIGH.
ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE
TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW
CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW
LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG
ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE
FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST
FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S
NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS
MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT
STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA
DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN
DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT
MAINTAINED A DRY FORECAST FOR NOW.
VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT
AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW
PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW
PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS
A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST
HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL
PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925
MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A
FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR
SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT
OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A
SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY.
GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S
AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR
MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL
BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA
BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL
PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER
CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING
GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD
ONLY IN THE LOW-MID 60S.
LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...
MAINTAINED BLENDED GUIDANCE FOR MID-HIGH CHANCE POPS TUESDAY
EVENING/NIGHT WITH COLD FRONT BUT IF FRONT SLOWS
FURTHER...INSTABILITY MAY WANE ENOUGH TO GREATLY LIMIT COVERAGE OF
SHRA/TSRA. THEN ON WEDNESDAY...THE FRONT WILL STILL BE DROPPING
SOUTHWARD...KEEPING A CHANCE FOR THUNDER GOING. AIR MASS WILL ONLY
BE MODESTLY COOLER INITIALLY. THEN A MUCH COOLER AIRMASS WILL
FINALLY ARRIVE THURSDAY INTO FRIDAY AS EASTERN NOAM TROUGH DEEPENS
AND BRUSHES OUR AREA WHILE STRONG CANADIAN HIGH PRESSURE SPREADS
SOUTHWARD. 850 MB THERMAL TROUGH LOOKS TO ARRIVE THURSDAY NIGHT INTO
FRIDAY...WITH MID TO HIGH SINGLE DIGITS AT 850 MB. SO AFTER A COOLER
BUT BASICALLY SEASONABLE THURSDAY...FRIDAY WILL BE A TASTE OF AUTUMN
WITH HIGHS ONLY IN THE LOW-MID 70S AWAY FROM LAKE MICHIGAN AND
MID-UPPER 60S ON THE LAKEFRONT. HEIGHT RISES WILL QUICKLY RETURN
SATURDAY SO TEMPERATURES WILL WARM SLIGHTLY.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* OUTFLOW BOUNDARY HAS STALLED OVER ORD...PUSHED JUST WEST OF MDW.
WIND LIKELY TO STAY LIGHT SOUTH NOW AT ORD...EAST BECOMING SOUTH
AGAIN AT MDW.
* WEAKENING SHRA/TSRA IN VCNTY NEXT 1-2 HOURS.
* EVENTUAL WIND SHIFT TO NORTHEAST LATE THIS EVENING WITH COLD
FRONT.
* LOW MVFR CIGS LIKELY DEVELOPING LATE TONIGHT/EARLY SUNDAY
MORNING.
RATZER
//DISCUSSION...UPDATED 18Z...
SYNOPSIS...WARM MOIST SOUTHWEST FLOW AHEAD OF A WEAK COLD FRONT...
WHICH EXTENDED FROM NORTHERN LAKE MICHIGAN ACROSS CENTRAL WI TO NW
IA THIS AFTERNOON. THE FRONT WILL MOVE THROUGH NORTHERN ILLINOIS
THIS EVENING. HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT
LAKES SUNDAY WITH STRONG NORTHEAST WINDS DEVELOPING.
THUNDERSTORM CLUSTER OVER SOUTHEAST WI MOVING SOUTHEAST BUT NEW
DEVELOPMENT AHEAD AND WEST OF MAIN CLUSTER OF STORMS MAY CLIP FAR
NORTHEAST ILLINOIS MID TO LATE AFTERNOON. WEAK INSTABILITY AND
SOMEWHAT OF A CAP WILL LIMIT DEVELOPMENT AND EXPECT MOST OF THIS
ACTIVITY TO DRIFT ACROSS LAKE MICHIGAN. HAVE ADDED A VCTS FOR LOW
CHANCE OF THUNDER NEAR ORD THIS AFTERNOON.
INSTABILITY WILL CONTINUE TO BUILD THROUGH THE AFTERNOON. CONVERGENCE
ALONG THE FRONT WILL BE FAIRLY WEAK BUT SHOULD BE SUFFICIENT FOR
SCATTERED THUNDERSTORMS AHEAD OF AND ALONG THE COLD FRONT EARLY
THIS EVENING. THUNDERSTORMS SHOULD DIMINISH AND SHIFT SOUTH LATE
THIS EVENING. BEHIND THE FRONT WINDS WILL BECOME NORTHEAST. WINDS
WILL INCREASE TOWARDS MORNING. MODEL GUIDANCE SUGGESTING LOW MVFR
AND POSSIBLY EVEN IFR CIGS WILL DEVELOP BEHIND THE COLD FRONT. LOW
CIGS SHOULD LIFT BY AFTERNOON. EXPECT NORTHEAST WINDS 12 TO 20 KTS
THROUGH THE DAY SUNDAY.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* MEDIUM CONFIDENCE WITH WIND TRENDS THIS EVENING.
* MEDIUM CONFIDENCE THAT ADDITIONAL TSRA WILL REMAIN WELL
WEST/SOUTH OF ORD/MDW.
* HIGH CONFIDENCE IN WIND FORECAST BEHIND COLD FRONT LATE TONIGHT
AND SUNDAY.
* MEDIUM TO HIGH CONFIDENCE IN MVFR CIGS DEVELOPING LATE TONIGHT
BUT LOW TO MEDIUM CONFIDENCE IN TIMING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT THROUGH TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE.
WEDNESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
129 PM CDT
A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF
LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE
LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE
NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO
25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A
DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING
SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS
CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR
THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL
CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL
BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES
ARE EXPECTED.
THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST
SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER
GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A
CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS
SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE
EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF
ON EXTENDING THE ADVISORY INTO THIS PERIOD.
THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL
LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW
PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA.
LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP
ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM SUNDAY TO 11 PM
SUNDAY.
IN...BEACH HAZARDS STATEMENT...INZ001...4 AM SUNDAY TO 11 PM SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM
SUNDAY.
SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11
PM SUNDAY.
&&
$$
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 TOPEKA KS
1151 PM CDT Thu Sep 5 2013
.SHORT TERM...(This Evening through Friday)
Issued at 243 PM CDT THU SEP 5 2013
Upper level high remains centered over Colorado through tomorrow
while a surface high continues to retreat eastward. An area of
isolated showers has continued to move closer to our northern
areas...although most of the precip is not reaching the ground. The
12z NAM supports moisture convergence in this area along with an
axis of slight elevated instability which extends into northeast
Kansas. The HRRR has also been consistent with bringing these
showers into our area. If showers are able to persist within the dry
air and weak advection only northern row of counties look to be
affected the next few hours with an overall diminishing trend
towards the evening.
High temperatures look to reach the low to mid 90s today which is
above normal for this time of year. The skies will remain partly
cloudy especially across northern areas closer to the ongoing shower
activity. Tonight WAA will again set up across eastern Nebraska well
north of the northeast Kansas to keep the entire area dry. Low
temperatures tonight appear to be on track for the mid to upper 60s.
Low level winds will gradually veer allowing warming 850 temps to
spread into eastern KS therefore high temperatures will make it into
the low to mid 90s again tomorrow. With more mixing likely tomorrow
during the day winds will likely increase to around 10 mph with
gusts up to 20 mph possible.
.LONG TERM...(Friday Night through Thursday)
Issued at 243 PM CDT THU SEP 5 2013
The forecast for Friday night through Tuesday is essentially one
of persistence. Other than subtle day to day differences, the
weather pattern will be fairly stagnant through the period with a
large area of upper level high pressure slowly drifting from west
to east across the plains and into the Ohio valley. High
temperatures will be consistently in the 90s. The hottest day
currently appears to be Saturday with southwest surface winds, the
upper ridge almost directly overhead, and the warmest 850 temps of
the week in place all pointing to highs in the middle to upper
90s. There will be a couple of very weak upper disturbances that
may provide enough lift for a shower or thunderstorm, mainly
northeast of the local forecast area along a weak convergence
zone, late on Saturday. Will watch these features in future
forecasts but expect dry conditions for the most part through the
weekend.
There are a couple of stronger northern stream short wave troughs
that come over the top of the ridge next week. The trough crossing
the Dakotas on Monday will push a cold front to the south, but
expect this front to lose its forward progression and stall over
northern Nebraska. The second of the stronger troughs will cross
the Dakotas late Tuesday and should successfully push the cold
front through the forecast area by late Wednesday. Much of the
upper forcing will remain well to the north, and surface
convergence is not expected to be particularly strong, but may be
sufficient for scattered storms along the incoming front. Cooler
and drier air with almost meridional flow aloft will follow the
frontal passage and expect the end of next week to be both cooler
and dry.
&&
.AVIATION...(For the 06Z TAFs through 06Z Friday Night)
Issued at 1151 PM CDT THU SEP 5 2013
With a lack of large scale forcing and the 00Z RAOB still showing
a decent dry slot around 800MB, VFR conditions are expected to
prevail through the day. Lows are expected to remain warm enough
with just enough mixing to preclude any ground fog formation.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...Sanders
LONG TERM...Barjenbruch
AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS JACKSON KY
740 PM EDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 740 PM EDT SAT SEP 7 2013
BASED ON THE LATEST HRRR AND 18Z NAM...HAVE BACKED OFF ON POPS LATE
TONIGHT WITH VERY LITTLE CHANCE OF SEEING MUCH ACTIVITY UNTIL AFTER
12Z. IN FACT...CEILINGS TO THE NORTH ARE STILL 12KFT OR HIGHER WITH
VERY LITTLE EVIDENCE OF CEILINGS COMING DOWN. MOISTURE APPEARS VERY
LIMITED IN THE LOWER LEVELS AND GIVEN THE LACK OF INSTABILITY...HARD
TO SEE MUCH SHOWER ACTIVITY DEVELOPING OVERNIGHT. ALSO SPED UP THE
TEMPERATURE DROP OFF THIS EVENING AS CLEAR SKIES SHOULD ALLOW FOR A
QUICK DROP IN TEMPERATURES THIS EVENING...WITH SOME OF THE VALLEYS
POSSIBLY SINKING INTO THE 50S BY LATE EVENING PRIOR TO THE ARRIVAL OF
THE MID/HIGH CLOUDS FROM THE NORTH. CLOUDS SHOULD EVENTUALLY SLOW
DOWN THE TEMPERATURE FALL FOR THE SECOND HALF OF THE
NIGHT...ESPECIALLY IN THE NORTH. CLOUDS WILL EVENTUALLY REACH THE
TENNESSEE BORDER BY 09Z. ZFP UPDATE WILL BE OUT SOON...BUT NDFD GRIDS
HAVE ALREADY BEEN SENT.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 245 PM EDT SAT SEP 7 2013
18Z SFC ANALYSIS SHOWS RETREATING HIGH PRESSURE THROUGH EAST KENTUCKY
MAKING FOR A VERY PLEASANT...WARM...AND MOSTLY SUNNY DAY.
TEMPERATURES HAVE GENERALLY CLIMBED INTO THE LOWER 80S ON THEIR WAY
TO THE MID 80S. MEANWHILE...DEWPOINTS ACROSS THE AREA ARE HOLDING IN
THE LOWER 60S FOR MOST OF THE AREA...MID 60S NEAR THE TENNESSEE
BORDER...UPPER 50S NORTH OF INTERSTATE 64.
THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM PART OF
THE FORECAST WITH A LARGE RIDGE TO THE IMMEDIATE WEST OF THE AREA AND
TROUGHING TO THE NORTHEAST. BETWEEN THESE...A COUPLE OF SHORTWAVES
WILL PASS OVER THE OHIO VALLEY THROUGH SUNDAY NIGHT. ONE OF THESE...
PASSES BY JUST TO THE EAST ON SUNDAY AND WILL BRIEFLY BUCKLE THE
WESTERN RIDGE THROUGH MIDDAY SUNDAY. GIVEN THE MODEL AGREEMENT...HAVE
FOLLOWED THE HIGHER RESOLUTION NAM12 FOR WX SPECIFICS.
SENSIBLE WEATHER WILL FEATURE A MILD NIGHT WITH HIGHER DEWPOINTS AND
MORE CLOUDS KEEPING THE VALLEYS FROM DROPPING OFF AS MUCH AS LAST
NIGHT. LIKEWISE...EXPECT THE FOG TO BE LESS PREVALENT IN THE ALL BUT
THE DEEPER VALLEYS BY MORNING. THE APPROACHING COLD FRONT WILL BRING
A THREAT OF SHOWERS OR THUNDERSTORMS TO NORTHERN PARTS OF EAST
KENTUCKY BY DAWN. THE FRONT DROPS THROUGH THE CWA DURING THE DAY
SUNDAY AND COMBINED WITH PEAK HEATING WILL BRING A BETTER CHANCE OF
SHOWERS AND THUNDERSTORMS TO THE ENTIRE AREA. RIDGING BUILDS BACK IN
ALOFT BY EVENING...THOUGH...AS THE MID LEVEL SHORTWAVE PASSES AND
THIS SHOULD PUT AN END TO THE CONVECTION THREAT SHORTLY AFTER 00Z.
ANOTHER MILD NIGHT FOLLOWS WITH PATCHY VALLEY FOG ANTICIPATED BY
DAWN.
USED THE CONSSHORT AND ITS BC BROTHER TO JUMP START THE TD AND WIND
GRIDS THROUGH 12Z SUNDAY...CONSALL THEREAFTER. FOR TEMPERATURES...
USED THE OBS DATABASE AS A BASIS FOR THE DIURNAL CURVE AND MODIFIED
CONSALL MAX AND MIN TEMPS...NOT TOO MUCH TERRAIN ADJUSTMENT AT NIGHT
GIVEN THE BUILDING CLOUDS TONIGHT AND FRONTAL CLOUDS SUNDAY NIGHT. AS
FOR POPS...ENDED UP MOST SIMILAR TO THE MET NUMBERS THROUGH THE SHORT
TERM PERIOD.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 245 PM EDT SAT SEP 7 2013
STILL DECENT AGREEMENT AMONGST THE EXTENDED MODELS FOR DAYS 3 THRU 7
OF THE FORECAST. HIGH PRESSURE WILL BE THE DOMINANT FEATURE ON
MONDAY...WITH PARTLY CLOUDY SKIES AND DRY CONDITIONS EXPECTED. A
SERIES OF WEAK WEATHER SYSTEM WILL BRING ISOLATED TO SCATTERED
SHOWERS AND STORMS TO THE AREA AS THEY MOVE ACROSS THE EASTERN THIRD
OF THE CONUS TUESDAY THROUGH THURSDAY. THE BEST CHANCE OF RAIN WILL
LIKELY OCCUR ON THURSDAY AS A SLUGGISH FRONTAL BOUNDARY INTERACTS
WITH THE TERRAIN OF EASTERN KENTUCKY. TEMPERATURES WILL TOP OUT
MOSTLY IN THE MID TO UPPER 80S THROUGH THURSDAY. HIGHS ON FRIDAY AND
SATURDAY WILL BE MUCH COOLER BEHIND THE DEPARTING FRONT...WITH HIGHS
TOPPING OUT MOSTLY IN THE MID TO UPPER 70S EACH DAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 740 PM EDT SAT SEP 7 2013
VFR CONDITIONS WILL CONTINUE TO DOMINATE THROUGH MOST OF THE TAF
FORECAST PERIOD. SOME PATCHY FOG WILL BE POSSIBLE IN THE VALLEYS LATE
TONIGHT...BUT SHOULD NOT IMPACT TAFS...AS CLOUDS PUT THE CLAMPS ON
FOG PRODUCTION LATE TONIGHT. THESE CLOUDS SHOULD MAINLY BE MID TO
HIGH LEVEL CLOUDS WITH VERY LITTLE IMPACT TO AVIATION. A THREAT FOR A
STRAY SHOWER OR THUNDERSTORM WILL BE SEEN TOMORROW...BUT CONFIDENCE
IS LOW ON ANY SHOWERS OR STORMS AFFECTING THE TAF SITES...SO NO NEED
TO INCLUDE AT THIS TIME.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...GREIF
LONG TERM...AR
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1147 PM EDT SAT SEP 7 2013
.AVIATION...
//DISCUSSION...
A WEAK COLD FRONTAL BOUNDARY WILL SETTLE ACROSS SOUTHEAST MICHIGAN
EARLY THIS MORNING. THIS WILL LEAD TO SOME EXPANSION OF LOW STRATUS
ACROSS THE REGION FOR THE DURATION OF THE MORNING PERIOD. RECENT
SATELLITE AND OBSERVATIONAL TRENDS SUPPORT PREDOMINATE MVFR
CONDITIONS...ALTHOUGH A BRIEF PERIOD OF IFR RIGHT AROUND DAYBREAK
REMAINS PLAUSIBLE. WINDS BECOME FIRMLY OUT OF THE NORTHEAST WITH
THE FRONTAL PASSAGE. DRIER AIR WORKS IN ON SUNDAY LIFTING AND
EVENTUALLY CLEARING ANY RESIDUAL STRATUS BY MIDDAY.
FOR DTW...A VEERING WIND ACCOMPANIES THE FRONTAL PASSAGE EARLY THIS
MORNING...SETTLING TO NORTHEAST 08-09Z.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILINGS BELOW 5000 FT 09Z-16Z THIS MORNING.
&&
.PREV DISCUSSION...ISSUED 834 PM EDT SAT SEP 7 2013
UPDATE...
STEADY DETERIORATION OF AVAILABLE INSTABILITY WITHIN THE PRE-FRONTAL
ENVIRONMENT THANKS TO THE EARLIER RAINFALL...PERSISTENT MID CLOUD
DECK AND NOW THE LOSS OF HEATING WILL LEAVE AN INCREASINGLY
UNSUPPORTIVE ENVIRONMENT FOR BETTER PRECIPITATION COVERAGE AND
OVERALL CONVECTIVE ORGANIZATION THROUGH THE REST OF THE EVENING.
ONGOING ACTIVITY CURRENTLY ANCHORED WITHIN THE GREATEST SLIVER OF
INSTABILITY (SBCAPE ~1200 J/KG) STRETCHING ACROSS THE SAGINAW
VALLEY/NORTHERN THUMB. THIS CORRIDOR WILL REMAIN THE MOST FAVORED
CORRIDOR FOR ADDITIONAL DEVELOPMENT OVER THE NEXT 2-3 HOURS.
ELSEWHERE...WILL RETAIN A LOW POP INTO THE EARLY PORTION OF THE
NIGHT TO RECOGNIZE THE POSSIBILITY FOR SOME WEAK PRE-FRONTAL
CONVERGENCE TO WORK INTO THE RESIDUAL STEEPER LAPSE RATES AND
GENERATE A FEW GARDEN VARIETY CELLS. STEADY INFLUX OF LOW LEVEL
MOISTURE WITH THE ONSET OF SHALLOW POST-FRONTAL COOLING WILL ALLOW
FOR SOME DEVELOPMENT/EXPANSION LATE TONIGHT.
GOING FORECAST IN PRETTY GOOD SHAPE...JUST SOME MINOR ADJUSTMENTS TO
ACCOUNT FOR ONGOING RADAR TRENDS AND EXPECTED OVERNIGHT CLOUD COVER
EVOLUTION.
PREV DISCUSSION...ISSUED 403 PM EDT SAT SEP 7 2013
SHORT TERM...THIS EVENING TONIGHT
DIRECT CYCLONIC VORTICITY ADVECTION WAS EFFICIENT ENOUGH TO ALLOW
WIDESPREAD PRECIPITATION TO FALL OUT OF A MIDCLOUD DECK 8-10KFT
AGL...THROUGHOUT MUCH IF NOT ALL OF SOUTHEASTERN MICHIGAN EARLIER
THIS AFTERNOON. A DRY ATMOSPHERE BELOW 8000FT AGL...COMPOUNDED TO
THE FORECAST DIFFICULTY.
THE QUESTION REMAINS WHAT SORT OF RECOVERY CAN HAPPEN HERE ON AN
EARLY SEPTEMBER AFTERNOON WITH OPAQUE CLOUDS ABOVE...AND A
EVAPORATIVE/RAIN COOLED NEAR SURFACE LAYER BELOW. SURFACE
OBSERVATIONS ARE SHOWING SOME LOW 80S CREEPING INTO WESTERN LOWER
MICHIGAN AND SOME BREAKS IN THE CLOUDS EAST OF THE ANVIL OVER FAR
SOUTHEASTERN WISCONSIN. THE LEGITIMATE COLD FRONT IS CURRENTLY UP
OVER PORTIONS OF NORTHERN LAKE HURON...NORTH OF ROGERS CITY AND
PRESQUE ISLE. GIVEN THE BREAKS WITH UNIFORM SOUTHWESTERLY FLOW STILL
EXPECT TEMPERATURES TO CLIMB ABOVE 80 DEGREES. RAP BASED SPC
MESOANALYSIS DOES SHOW SOME OF THIS RECOVERY WITH MLCAPES AT/AROUND
1000 J/KG INVOF MIDLAND COUNTY THUNDERSTORM. THEREFORE...MUCH OF THE
INFORMATION PROVIDED IN THE MORNING UPDATE DISCUSSION REMAINS VALID.
NEW INFORMATION IS THE MIDLAND THUNDERSTORM/CELL THAT IS SHOWING
ORGANIZATION WITH SOME FORWARD LEAN AND DECENT MIDLEVEL CONVERGENCE.
THEREFORE...THUNDERSTORMS ARE STILL EXPECTED TO POSE AN ISOLATED
RISK OF STRONG WINDS. BETTER POTENTIAL REMAINS OVER THE NORTHERN CWA
20-01Z...A BRIEF WINDOW ACROSS THE SOUTHERN CWA 00-03Z.
THE COLD FRONT SHOULD PUSH STEADILY THROUGH THE CWA FROM NORTH TO
SOUTH BETWEEN 03-12Z. LOW STRATUS ALREADY EXISTS NORTH OF LAKE
HURON/GEORGIAN BAY AND MAY BE SHOWING A PRECURSOR TO TOMORROW
MORNING...WHERE AT LEAST A FRACTION OF THE NWP IS SHOWING A LOW
STRATUS BLANKET 12Z.
LONG TERM...SUNDAY THROUGH NEXT SATURDAY
COLD FRONT WILL HAVE CLEARED THE STATE LINE BY SUNDAY MORNING
LEAVING HIGH PRESSURE TO BUILD IN DURING THE DAY. CONSIDERATION OF
MOISTURE FLUX OFF LAKE HURON IN COMBINATION WITH FORECAST SOUNDINGS
CONTINUE TO SUPPORT THE IDEA OF MOSTLY CLOUDY SKIES TO START THE DAY
ACROSS SOUTHEAST MICHIGAN...AS MOISTURE LOCKS IN UNDER AND
INVERSION. MUCH DRIER AIR SHOULD START TO ARRIVE FROM CANADA DURING
THE AFTERNOON...AND SHOULD ERODE THE CLOUD DECK AS IT MIXES DOWN TO
THE SURFACE. DRIZZLE COULD BE A POSSIBILITY IF THE LOW LEVELS BECOME
SATURATED ENOUGH UNDER THE DRIER AIR ARRIVING ABOVE THE
INVERSION...ALTHOUGH IT IS NOT MENTIONED IN THE FORECAST AT THIS
TIME. CURRENT FORECAST SOUNDINGS DO NOT LOOK SATURATED ENOUGH TO
JUSTIFY A MENTION...HOWEVER CAN SEE POTENTIAL FOR MODELS TO
UNDERPLAY MOISTURE OFF LAKE HURON IN THE LOWER LEVELS. THIS WILL BE
A SHORTER-TERM FORECAST CONCERN. THE COMBINATION OF COLD AIR
ADVECTION AND NORTHEAST FLOW OFF THE LAKES WILL KEEP TEMPERATURES
COOL TOMORROW...ONLY REACHING INTO THE 60S ACROSS THE THUMB AND NEAR
THE LAKESHORES...AND IN THE LOW/MID 70S FURTHER INLAND.
UPPER LOW OVER BRITISH COLUMBIA AND WASHINGTON STATE WILL TRACK
EAST...OPENING AND MOVING INTO UPPER MIDWEST/SOUTHERN CANADA BY
MONDAY NIGHT. SURFACE LOW PRESSURE WILL BECOME ORGANIZED OVER THE
NORTHERN PLAINS AND MIDWEST ON MONDAY...WHICH WILL ALLOW A WARM
FRONT TO LIFT ACROSS MICHIGAN. MODELS ARE NOW SHOWING A GOOD PUSH OF
THETA-E ADVECTION AND A BAND OF GOOD SYSTEM RELATIVE ISENTROPIC
ASCENT AS A WARM FRONT AND LOW-LEVEL JET LIFT THROUGH DURING THE
LATE MORNING AND AFTERNOON. THIS MAY BE ENOUGH FORCING TO ALLOW A
BAND OF SHOWERS/TSTORMS TO MOVE THROUGH BEFORE WE BECOME ENTRENCHED
IN A MORE STABLE WARM SECTOR.
IMPRESSIVE WARM AIR ADVECTION LOOKS TO OCCUR LATE MONDAY THROUGH
TUESDAY AS THE LOW MOVES INTO THE NORTHERN GREAT LAKES AND STRONG
SOUTH TO SOUTHWEST FLOW CONTINUES TO PUMP WARMER AIR INTO THE AREA.
FORECAST SOUNDINGS LOOK EXTREMELY CAPPED PRIOR TO 18Z...UNTIL DEEPER
MIXING STARTS TO CHIP AWAY AT THE INVERSION. LOOKS LIKE ENOUGH OF AN
INVERSION WILL HOLD TO KEEP A DRY FORECAST...IN ADDITION TO THE COLD
FRONT REMAINING UPSTREAM DURING THE DAY. TUESDAY LOOKS BREEZY AND
HOT AS H850 TEMPERATURES RISE TO 20-22C AND ENOUGH MIXING LOOKS
PRESENT TO REALIZE ALL THE WARMING ALOFT. SOME SUNSHINE SHOULD HELP
BOOST TEMPERATURES INTO THE LOW OR EVEN MID 90S. BREEZY
CONDITIONS...POSSIBLY EVEN WINDY...ALSO LOOK LIKELY WITH GFS/NAM
SOUNDINGS SHOWING A SOLID CORE OF 20 KNOTS EVEN AT THE VERY BOTTOM
OF THE MIXED LAYER...WITH HIGHER SPEEDS EVEN FURTHER UP. BIGGEST
CONCERN FOR THIS DAY WILL ACTUALLY BE FOR FIRE WEATHER INTERESTS
WITH HOT AND BREEZY CONDITIONS. DEWPOINTS LOOK TO SETTLE INTO THE
MID 60S (PER GFS SOUNDINGS) BUT COULD GO LOWER IF DRIER NAM
VERIFIES. THIS SHOULD KEEP MIN RELATIVE HUMIDITIES ABOVE 30 PERCENT.
WILL WATCH TRENDS HOWEVER.
COLD FRONT WILL DROP THROUGH TUESDAY EVENING THROUGH WEDNESDAY
MORNING...WITH LOW-LEVEL FORCING AIDED BY RIGHT ENTRANCE REGION
FORCING ALOFT. THIS SHOULD PROVIDE AT LEAST A SCATTERED COVERAGE OF
SHOWERS/TSTORMS ACROSS THE AREA AS THE FRONT DROPS THROUGH.
UPPER TROUGHING WILL SET UP OVER THE GREAT LAKES WEDNESDAY THROUGH
THURSDAY...WITH UPPER SHORTWAVES ROTATING THROUGH THE MAIN TROUGH
SENDING REINFORCING SHOTS OF COLD AIR DOWN INTO THE GREAT LAKES.
THIS SHOULD DROP TEMPERATURES BACK DOWN TO BELOW NORMAL FOR THE END
OF THE WEEK...EVEN AS HIGH PRESSURE BUILDS BACK IN ON FRIDAY.
MARINE...
THE PASSAGE OF A COLD FRONT TONIGHT WILL USHER IN A SOLID 12 HOUR
PERIOD OF STRONG NORTH NORTHEAST WINDS THAT WILL GUST TO NEAR GALES
ACROSS THE OPEN WATERS OF CENTRAL LAKE HURON AND POSSIBLY OUTER
SAGINAW BAY AND THE EXPOSED NEARSHORE WATERS OF THE THUMB.
LIKEWISE...THESE SAME LOCATIONS WILL SEE SIGNIFICANT WAVE HEIGHTS
BUILD INTO THE 6 TO 8 FOOT RANGE DURING THIS TIME PERIOD WITH THE
REMAINING NEARSHORE ZONES GENERALLY EXPERIENCING SIG WAVES OF 6 FEET
OR LESS. WINDS WILL EASE BY SUNDAY EVENING FOLLOWED BY SUBSIDING
WAVES BY LATE SUNDAY NIGHT. SMALL CRAFT ADVISORIES HAVE BEEN ISSUED
ACCORDINGLY FOR ALL NEARSHORE ZONES OF LAKE HURON. A REDUCED FETCH
FOR THE SOUTHERN WATERS OF LAKE SAINT CLAIR AND MICHIGAN WATERS OF
LAKE ERIE WILL LIMIT THEIR SIG WAVES TO AROUND 3 FEET.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS
FROM PORT AUSTIN TO PORT SANILAC...UNTIL 10 PM SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT SANILAC TO PORT
HURON...FROM 5 AM SUNDAY TO 4 AM MONDAY.
SMALL CRAFT ADVISORY...INNER SAGINAW BAY...FROM 5 AM SUNDAY TO 4 PM
SUNDAY.
LAKE ST CLAIR...
SMALL CRAFT ADVISORY...FROM 8 AM SUNDAY TO 8 PM SUNDAY.
MI WATERS OF LAKE ERIE...
SMALL CRAFT ADVISORY...FROM 8 AM SUNDAY TO 8 PM SUNDAY.
&&
$$
AVIATION.....MR
UPDATE.......MR
SHORT TERM...CB
LONG TERM....HLO
MARINE.......CB
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS
ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
834 PM EDT SAT SEP 7 2013
.UPDATE...
STEADY DETERIORATION OF AVAILABLE INSTABILITY WITHIN THE PRE-FRONTAL
ENVIRONMENT THANKS TO THE EARLIER RAINFALL...PERSISTENT MID CLOUD
DECK AND NOW THE LOSS OF HEATING WILL LEAVE AN INCREASINGLY
UNSUPPORTIVE ENVIRONMENT FOR BETTER PRECIPITATION COVERAGE AND
OVERALL CONVECTIVE ORGANIZATION THROUGH THE REST OF THE EVENING.
ONGOING ACTIVITY CURRENTLY ANCHORED WITHIN THE GREATEST SLIVER OF
INSTABILITY (SBCAPE ~1200 J/KG) STRETCHING ACROSS THE SAGINAW
VALLEY/NORTHERN THUMB. THIS CORRIDOR WILL REMAIN THE MOST FAVORED
CORRIDOR FOR ADDITIONAL DEVELOPMENT OVER THE NEXT 2-3 HOURS.
ELSEWHERE...WILL RETAIN A LOW POP INTO THE EARLY PORTION OF THE
NIGHT TO RECOGNIZE THE POSSIBILITY FOR SOME WEAK PRE-FRONTAL
CONVERGENCE TO WORK INTO THE RESIDUAL STEEPER LAPSE RATES AND
GENERATE A FEW GARDEN VARIETY CELLS. STEADY INFLUX OF LOW LEVEL
MOISTURE WITH THE ONSET OF SHALLOW POST-FRONTAL COOLING WILL ALLOW
FOR SOME DEVELOPMENT/EXPANSION LATE TONIGHT.
GOING FORECAST IN PRETTY GOOD SHAPE...JUST SOME MINOR ADJUSTMENTS TO
ACCOUNT FOR ONGOING RADAR TRENDS AND EXPECTED OVERNIGHT CLOUD COVER
EVOLUTION.
&&
.AVIATION...ISSUED 717 PM EDT SAT SEP 7 2013
//DISCUSSION...
DIMINISHING INSTABILITY LEFT IN THE WAKE OF THE EARLIER RAINFALL
WILL MAINTAIN AT LEAST A LOWER PROBABILITY FOR THUNDERSTORMS TO
DEVELOP WITHIN THE 00-03Z PERIOD IN ADVANCE OF A COLD FRONT.
HOWEVER THIS POTENTIAL NOW APPEARS TOO LIMITED TO INCLUDE GIVEN A
LACK OF CURRENT RADAR SUPPORT AND THE SHRINKING WINDOW OF
OPPORTUNITY. PREVAILING SOUTHWESTERLIES THIS EVENING WILL VEER WITH
THE FRONTAL PASSAGE...SETTLING INTO A NORTHEAST DIRECTION FROM NORTH
TO SOUTH /05-09Z/. LOW LEVEL MOISTURE FILLING IN BEHIND THIS FRONT
WILL RESULT IN LOWERING CEILINGS THROUGH THE PRE-DAWN HOURS. A
PERIOD MVFR/IFR RESTRICTIONS WILL EXIST INTO THE MID MORNING
PERIOD.
FOR DTW...THUNDERSTORM POTENTIAL NOW APPEARS TOO LOW TO INCLUDE A
MENTION. PREVAILING SOUTHWEST FLOW WILL EXIST THROUGH THE REMAINDER
OF THE EVENING. A VEERING WIND ACCOMPANIES A FRONTAL PASSAGE DURING
THE EARLY MORNING PERIOD SETTLING TO NORTHEAST 08-09Z.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE IN THUNDERSTORM POTENTIAL THIS EVENING.
* HIGH CONFIDENCE IN CEILINGS BELOW 5000 FT 09Z-16Z SUNDAY MORNING.
&&
.PREV DISCUSSION...ISSUED 403 PM EDT SAT SEP 7 2013
SHORT TERM...THIS EVENING TONIGHT
DIRECT CYCLONIC VORTICITY ADVECTION WAS EFFICIENT ENOUGH TO ALLOW
WIDESPREAD PRECIPITATION TO FALL OUT OF A MIDCLOUD DECK 8-10KFT
AGL...THROUGHOUT MUCH IF NOT ALL OF SOUTHEASTERN MICHIGAN EARLIER
THIS AFTERNOON. A DRY ATMOSPHERE BELOW 8000FT AGL...COMPOUNDED TO
THE FORECAST DIFFICULTY.
THE QUESTION REMAINS WHAT SORT OF RECOVERY CAN HAPPEN HERE ON AN
EARLY SEPTEMBER AFTERNOON WITH OPAQUE CLOUDS ABOVE...AND A
EVAPORATIVE/RAIN COOLED NEAR SURFACE LAYER BELOW. SURFACE
OBSERVATIONS ARE SHOWING SOME LOW 80S CREEPING INTO WESTERN LOWER
MICHIGAN AND SOME BREAKS IN THE CLOUDS EAST OF THE ANVIL OVER FAR
SOUTHEASTERN WISCONSIN. THE LEGITIMATE COLD FRONT IS CURRENTLY UP
OVER PORTIONS OF NORTHERN LAKE HURON...NORTH OF ROGERS CITY AND
PRESQUE ISLE. GIVEN THE BREAKS WITH UNIFORM SOUTHWESTERLY FLOW STILL
EXPECT TEMPERATURES TO CLIMB ABOVE 80 DEGREES. RAP BASED SPC
MESOANALYSIS DOES SHOW SOME OF THIS RECOVERY WITH MLCAPES AT/AROUND
1000 J/KG INVOF MIDLAND COUNTY THUNDERSTORM. THEREFORE...MUCH OF THE
INFORMATION PROVIDED IN THE MORNING UPDATE DISCUSSION REMAINS VALID.
NEW INFORMATION IS THE MIDLAND THUNDERSTORM/CELL THAT IS SHOWING
ORGANIZATION WITH SOME FORWARD LEAN AND DECENT MIDLEVEL CONVERGENCE.
THEREFORE...THUNDERSTORMS ARE STILL EXPECTED TO POSE AN ISOLATED
RISK OF STRONG WINDS. BETTER POTENTIAL REMAINS OVER THE NORTHERN CWA
20-01Z...A BRIEF WINDOW ACROSS THE SOUTHERN CWA 00-03Z.
THE COLD FRONT SHOULD PUSH STEADILY THROUGH THE CWA FROM NORTH TO
SOUTH BETWEEN 03-12Z. LOW STRATUS ALREADY EXISTS NORTH OF LAKE
HURON/GEORGIAN BAY AND MAY BE SHOWING A PRECURSOR TO TOMORROW
MORNING...WHERE AT LEAST A FRACTION OF THE NWP IS SHOWING A LOW
STRATUS BLANKET 12Z.
LONG TERM...SUNDAY THROUGH NEXT SATURDAY
COLD FRONT WILL HAVE CLEARED THE STATE LINE BY SUNDAY MORNING
LEAVING HIGH PRESSURE TO BUILD IN DURING THE DAY. CONSIDERATION OF
MOISTURE FLUX OFF LAKE HURON IN COMBINATION WITH FORECAST SOUNDINGS
CONTINUE TO SUPPORT THE IDEA OF MOSTLY CLOUDY SKIES TO START THE DAY
ACROSS SOUTHEAST MICHIGAN...AS MOISTURE LOCKS IN UNDER AND
INVERSION. MUCH DRIER AIR SHOULD START TO ARRIVE FROM CANADA DURING
THE AFTERNOON...AND SHOULD ERODE THE CLOUD DECK AS IT MIXES DOWN TO
THE SURFACE. DRIZZLE COULD BE A POSSIBILITY IF THE LOW LEVELS BECOME
SATURATED ENOUGH UNDER THE DRIER AIR ARRIVING ABOVE THE
INVERSION...ALTHOUGH IT IS NOT MENTIONED IN THE FORECAST AT THIS
TIME. CURRENT FORECAST SOUNDINGS DO NOT LOOK SATURATED ENOUGH TO
JUSTIFY A MENTION...HOWEVER CAN SEE POTENTIAL FOR MODELS TO
UNDERPLAY MOISTURE OFF LAKE HURON IN THE LOWER LEVELS. THIS WILL BE
A SHORTER-TERM FORECAST CONCERN. THE COMBINATION OF COLD AIR
ADVECTION AND NORTHEAST FLOW OFF THE LAKES WILL KEEP TEMPERATURES
COOL TOMORROW...ONLY REACHING INTO THE 60S ACROSS THE THUMB AND NEAR
THE LAKESHORES...AND IN THE LOW/MID 70S FURTHER INLAND.
UPPER LOW OVER BRITISH COLUMBIA AND WASHINGTON STATE WILL TRACK
EAST...OPENING AND MOVING INTO UPPER MIDWEST/SOUTHERN CANADA BY
MONDAY NIGHT. SURFACE LOW PRESSURE WILL BECOME ORGANIZED OVER THE
NORTHERN PLAINS AND MIDWEST ON MONDAY...WHICH WILL ALLOW A WARM
FRONT TO LIFT ACROSS MICHIGAN. MODELS ARE NOW SHOWING A GOOD PUSH OF
THETA-E ADVECTION AND A BAND OF GOOD SYSTEM RELATIVE ISENTROPIC
ASCENT AS A WARM FRONT AND LOW-LEVEL JET LIFT THROUGH DURING THE
LATE MORNING AND AFTERNOON. THIS MAY BE ENOUGH FORCING TO ALLOW A
BAND OF SHOWERS/TSTORMS TO MOVE THROUGH BEFORE WE BECOME ENTRENCHED
IN A MORE STABLE WARM SECTOR.
IMPRESSIVE WARM AIR ADVECTION LOOKS TO OCCUR LATE MONDAY THROUGH
TUESDAY AS THE LOW MOVES INTO THE NORTHERN GREAT LAKES AND STRONG
SOUTH TO SOUTHWEST FLOW CONTINUES TO PUMP WARMER AIR INTO THE AREA.
FORECAST SOUNDINGS LOOK EXTREMELY CAPPED PRIOR TO 18Z...UNTIL DEEPER
MIXING STARTS TO CHIP AWAY AT THE INVERSION. LOOKS LIKE ENOUGH OF AN
INVERSION WILL HOLD TO KEEP A DRY FORECAST...IN ADDITION TO THE COLD
FRONT REMAINING UPSTREAM DURING THE DAY. TUESDAY LOOKS BREEZY AND
HOT AS H850 TEMPERATURES RISE TO 20-22C AND ENOUGH MIXING LOOKS
PRESENT TO REALIZE ALL THE WARMING ALOFT. SOME SUNSHINE SHOULD HELP
BOOST TEMPERATURES INTO THE LOW OR EVEN MID 90S. BREEZY
CONDITIONS...POSSIBLY EVEN WINDY...ALSO LOOK LIKELY WITH GFS/NAM
SOUNDINGS SHOWING A SOLID CORE OF 20 KNOTS EVEN AT THE VERY BOTTOM
OF THE MIXED LAYER...WITH HIGHER SPEEDS EVEN FURTHER UP. BIGGEST
CONCERN FOR THIS DAY WILL ACTUALLY BE FOR FIRE WEATHER INTERESTS
WITH HOT AND BREEZY CONDITIONS. DEWPOINTS LOOK TO SETTLE INTO THE
MID 60S (PER GFS SOUNDINGS) BUT COULD GO LOWER IF DRIER NAM
VERIFIES. THIS SHOULD KEEP MIN RELATIVE HUMIDITIES ABOVE 30 PERCENT.
WILL WATCH TRENDS HOWEVER.
COLD FRONT WILL DROP THROUGH TUESDAY EVENING THROUGH WEDNESDAY
MORNING...WITH LOW-LEVEL FORCING AIDED BY RIGHT ENTRANCE REGION
FORCING ALOFT. THIS SHOULD PROVIDE AT LEAST A SCATTERED COVERAGE OF
SHOWERS/TSTORMS ACROSS THE AREA AS THE FRONT DROPS THROUGH.
UPPER TROUGHING WILL SET UP OVER THE GREAT LAKES WEDNESDAY THROUGH
THURSDAY...WITH UPPER SHORTWAVES ROTATING THROUGH THE MAIN TROUGH
SENDING REINFORCING SHOTS OF COLD AIR DOWN INTO THE GREAT LAKES.
THIS SHOULD DROP TEMPERATURES BACK DOWN TO BELOW NORMAL FOR THE END
OF THE WEEK...EVEN AS HIGH PRESSURE BUILDS BACK IN ON FRIDAY.
MARINE...
THE PASSAGE OF A COLD FRONT TONIGHT WILL USHER IN A SOLID 12 HOUR
PERIOD OF STRONG NORTH NORTHEAST WINDS THAT WILL GUST TO NEAR GALES
ACROSS THE OPEN WATERS OF CENTRAL LAKE HURON AND POSSIBLY OUTER
SAGINAW BAY AND THE EXPOSED NEARSHORE WATERS OF THE THUMB.
LIKEWISE...THESE SAME LOCATIONS WILL SEE SIGNIFICANT WAVE HEIGHTS
BUILD INTO THE 6 TO 8 FOOT RANGE DURING THIS TIME PERIOD WITH THE
REMAINING NEARSHORE ZONES GENERALLY EXPERIENCING SIG WAVES OF 6 FEET
OR LESS. WINDS WILL EASE BY SUNDAY EVENING FOLLOWED BY SUBSIDING
WAVES BY LATE SUNDAY NIGHT. SMALL CRAFT ADVISORIES HAVE BEEN ISSUED
ACCORDINGLY FOR ALL NEARSHORE ZONES OF LAKE HURON. A REDUCED FETCH
FOR THE SOUTHERN WATERS OF LAKE SAINT CLAIR AND MICHIGAN WATERS OF
LAKE ERIE WILL LIMIT THEIR SIG WAVES TO AROUND 3 FEET.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS
FROM PORT AUSTIN TO PORT SANILAC...FROM 2 AM SUNDAY TO 10 PM
SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT SANILAC TO PORT
HURON...FROM 5 AM SUNDAY TO 4 AM MONDAY.
SMALL CRAFT ADVISORY...INNER SAGINAW BAY...FROM 5 AM SUNDAY TO 4 PM
SUNDAY.
LAKE ST CLAIR...
SMALL CRAFT ADVISORY...FROM 8 AM SUNDAY TO 8 PM SUNDAY.
MI WATERS OF LAKE ERIE...
SMALL CRAFT ADVISORY...FROM 8 AM SUNDAY TO 8 PM SUNDAY.
&&
$$
UPDATE.......MR
AVIATION.....MR
SHORT TERM...CB
LONG TERM....HLO
MARINE.......CB
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
717 PM EDT SAT SEP 7 2013
.AVIATION...
//DISCUSSION...
DIMINISHING INSTABILITY LEFT IN THE WAKE OF THE EARLIER RAINFALL
WILL MAINTAIN AT LEAST A LOWER PROBABILITY FOR THUNDERSTORMS TO
DEVELOP WITHIN THE 00-03Z PERIOD IN ADVANCE OF A COLD FRONT.
HOWEVER THIS POTENTIAL NOW APPEARS TOO LIMITED TO INCLUDE GIVEN A
LACK OF CURRENT RADAR SUPPORT AND THE SHRINKING WINDOW OF
OPPORTUNITY. PREVAILING SOUTHWESTERLIES THIS EVENING WILL VEER WITH
THE FRONTAL PASSAGE...SETTLING INTO A NORTHEAST DIRECTION FROM NORTH
TO SOUTH /05-09Z/. LOW LEVEL MOISTURE FILLING IN BEHIND THIS FRONT
WILL RESULT IN LOWERING CEILINGS THROUGH THE PRE-DAWN HOURS. A
PERIOD MVFR/IFR RESTRICTIONS WILL EXIST INTO THE MID MORNING
PERIOD.
FOR DTW...THUNDERSTORM POTENTIAL NOW APPEARS TOO LOW TO INCLUDE A
MENTION. PREVAILING SOUTHWEST FLOW WILL EXIST THROUGH THE REMAINDER
OF THE EVENING. A VEERING WIND ACCOMPANIES A FRONTAL PASSAGE DURING
THE EARLY MORNING PERIOD SETTLING TO NORTHEAST 08-09Z.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE IN THUNDERSTORM POTENTIAL THIS EVENING.
* HIGH CONFIDENCE IN CEILINGS BELOW 5000 FT 09Z-16Z SUNDAY MORNING.
&&
.PREV DISCUSSION...ISSUED 403 PM EDT SAT SEP 7 2013
SHORT TERM...THIS EVENING TONIGHT
DIRECT CYCLONIC VORTICITY ADVECTION WAS EFFICIENT ENOUGH TO ALLOW
WIDESPREAD PRECIPITATION TO FALL OUT OF A MIDCLOUD DECK 8-10KFT
AGL...THROUGHOUT MUCH IF NOT ALL OF SOUTHEASTERN MICHIGAN EARLIER
THIS AFTERNOON. A DRY ATMOSPHERE BELOW 8000FT AGL...COMPOUNDED TO
THE FORECAST DIFFICULTY.
THE QUESTION REMAINS WHAT SORT OF RECOVERY CAN HAPPEN HERE ON AN
EARLY SEPTEMBER AFTERNOON WITH OPAQUE CLOUDS ABOVE...AND A
EVAPORATIVE/RAIN COOLED NEAR SURFACE LAYER BELOW. SURFACE
OBSERVATIONS ARE SHOWING SOME LOW 80S CREEPING INTO WESTERN LOWER
MICHIGAN AND SOME BREAKS IN THE CLOUDS EAST OF THE ANVIL OVER FAR
SOUTHEASTERN WISCONSIN. THE LEGITIMATE COLD FRONT IS CURRENTLY UP
OVER PORTIONS OF NORTHERN LAKE HURON...NORTH OF ROGERS CITY AND
PRESQUE ISLE. GIVEN THE BREAKS WITH UNIFORM SOUTHWESTERLY FLOW STILL
EXPECT TEMPERATURES TO CLIMB ABOVE 80 DEGREES. RAP BASED SPC
MESOANALYSIS DOES SHOW SOME OF THIS RECOVERY WITH MLCAPES AT/AROUND
1000 J/KG INVOF MIDLAND COUNTY THUNDERSTORM. THEREFORE...MUCH OF THE
INFORMATION PROVIDED IN THE MORNING UPDATE DISCUSSION REMAINS VALID.
NEW INFORMATION IS THE MIDLAND THUNDERSTORM/CELL THAT IS SHOWING
ORGANIZATION WITH SOME FORWARD LEAN AND DECENT MIDLEVEL CONVERGENCE.
THEREFORE...THUNDERSTORMS ARE STILL EXPECTED TO POSE AN ISOLATED
RISK OF STRONG WINDS. BETTER POTENTIAL REMAINS OVER THE NORTHERN CWA
20-01Z...A BRIEF WINDOW ACROSS THE SOUTHERN CWA 00-03Z.
THE COLD FRONT SHOULD PUSH STEADILY THROUGH THE CWA FROM NORTH TO
SOUTH BETWEEN 03-12Z. LOW STRATUS ALREADY EXISTS NORTH OF LAKE
HURON/GEORGIAN BAY AND MAY BE SHOWING A PRECURSOR TO TOMORROW
MORNING...WHERE AT LEAST A FRACTION OF THE NWP IS SHOWING A LOW
STRATUS BLANKET 12Z.
LONG TERM...SUNDAY THROUGH NEXT SATURDAY
COLD FRONT WILL HAVE CLEARED THE STATE LINE BY SUNDAY MORNING
LEAVING HIGH PRESSURE TO BUILD IN DURING THE DAY. CONSIDERATION OF
MOISTURE FLUX OFF LAKE HURON IN COMBINATION WITH FORECAST SOUNDINGS
CONTINUE TO SUPPORT THE IDEA OF MOSTLY CLOUDY SKIES TO START THE DAY
ACROSS SOUTHEAST MICHIGAN...AS MOISTURE LOCKS IN UNDER AND
INVERSION. MUCH DRIER AIR SHOULD START TO ARRIVE FROM CANADA DURING
THE AFTERNOON...AND SHOULD ERODE THE CLOUD DECK AS IT MIXES DOWN TO
THE SURFACE. DRIZZLE COULD BE A POSSIBILITY IF THE LOW LEVELS BECOME
SATURATED ENOUGH UNDER THE DRIER AIR ARRIVING ABOVE THE
INVERSION...ALTHOUGH IT IS NOT MENTIONED IN THE FORECAST AT THIS
TIME. CURRENT FORECAST SOUNDINGS DO NOT LOOK SATURATED ENOUGH TO
JUSTIFY A MENTION...HOWEVER CAN SEE POTENTIAL FOR MODELS TO
UNDERPLAY MOISTURE OFF LAKE HURON IN THE LOWER LEVELS. THIS WILL BE
A SHORTER-TERM FORECAST CONCERN. THE COMBINATION OF COLD AIR
ADVECTION AND NORTHEAST FLOW OFF THE LAKES WILL KEEP TEMPERATURES
COOL TOMORROW...ONLY REACHING INTO THE 60S ACROSS THE THUMB AND NEAR
THE LAKESHORES...AND IN THE LOW/MID 70S FURTHER INLAND.
UPPER LOW OVER BRITISH COLUMBIA AND WASHINGTON STATE WILL TRACK
EAST...OPENING AND MOVING INTO UPPER MIDWEST/SOUTHERN CANADA BY
MONDAY NIGHT. SURFACE LOW PRESSURE WILL BECOME ORGANIZED OVER THE
NORTHERN PLAINS AND MIDWEST ON MONDAY...WHICH WILL ALLOW A WARM
FRONT TO LIFT ACROSS MICHIGAN. MODELS ARE NOW SHOWING A GOOD PUSH OF
THETA-E ADVECTION AND A BAND OF GOOD SYSTEM RELATIVE ISENTROPIC
ASCENT AS A WARM FRONT AND LOW-LEVEL JET LIFT THROUGH DURING THE
LATE MORNING AND AFTERNOON. THIS MAY BE ENOUGH FORCING TO ALLOW A
BAND OF SHOWERS/TSTORMS TO MOVE THROUGH BEFORE WE BECOME ENTRENCHED
IN A MORE STABLE WARM SECTOR.
IMPRESSIVE WARM AIR ADVECTION LOOKS TO OCCUR LATE MONDAY THROUGH
TUESDAY AS THE LOW MOVES INTO THE NORTHERN GREAT LAKES AND STRONG
SOUTH TO SOUTHWEST FLOW CONTINUES TO PUMP WARMER AIR INTO THE AREA.
FORECAST SOUNDINGS LOOK EXTREMELY CAPPED PRIOR TO 18Z...UNTIL DEEPER
MIXING STARTS TO CHIP AWAY AT THE INVERSION. LOOKS LIKE ENOUGH OF AN
INVERSION WILL HOLD TO KEEP A DRY FORECAST...IN ADDITION TO THE COLD
FRONT REMAINING UPSTREAM DURING THE DAY. TUESDAY LOOKS BREEZY AND
HOT AS H850 TEMPERATURES RISE TO 20-22C AND ENOUGH MIXING LOOKS
PRESENT TO REALIZE ALL THE WARMING ALOFT. SOME SUNSHINE SHOULD HELP
BOOST TEMPERATURES INTO THE LOW OR EVEN MID 90S. BREEZY
CONDITIONS...POSSIBLY EVEN WINDY...ALSO LOOK LIKELY WITH GFS/NAM
SOUNDINGS SHOWING A SOLID CORE OF 20 KNOTS EVEN AT THE VERY BOTTOM
OF THE MIXED LAYER...WITH HIGHER SPEEDS EVEN FURTHER UP. BIGGEST
CONCERN FOR THIS DAY WILL ACTUALLY BE FOR FIRE WEATHER INTERESTS
WITH HOT AND BREEZY CONDITIONS. DEWPOINTS LOOK TO SETTLE INTO THE
MID 60S (PER GFS SOUNDINGS) BUT COULD GO LOWER IF DRIER NAM
VERIFIES. THIS SHOULD KEEP MIN RELATIVE HUMIDITIES ABOVE 30 PERCENT.
WILL WATCH TRENDS HOWEVER.
COLD FRONT WILL DROP THROUGH TUESDAY EVENING THROUGH WEDNESDAY
MORNING...WITH LOW-LEVEL FORCING AIDED BY RIGHT ENTRANCE REGION
FORCING ALOFT. THIS SHOULD PROVIDE AT LEAST A SCATTERED COVERAGE OF
SHOWERS/TSTORMS ACROSS THE AREA AS THE FRONT DROPS THROUGH.
UPPER TROUGHING WILL SET UP OVER THE GREAT LAKES WEDNESDAY THROUGH
THURSDAY...WITH UPPER SHORTWAVES ROTATING THROUGH THE MAIN TROUGH
SENDING REINFORCING SHOTS OF COLD AIR DOWN INTO THE GREAT LAKES.
THIS SHOULD DROP TEMPERATURES BACK DOWN TO BELOW NORMAL FOR THE END
OF THE WEEK...EVEN AS HIGH PRESSURE BUILDS BACK IN ON FRIDAY.
MARINE...
THE PASSAGE OF A COLD FRONT TONIGHT WILL USHER IN A SOLID 12 HOUR
PERIOD OF STRONG NORTH NORTHEAST WINDS THAT WILL GUST TO NEAR GALES
ACROSS THE OPEN WATERS OF CENTRAL LAKE HURON AND POSSIBLY OUTER
SAGINAW BAY AND THE EXPOSED NEARSHORE WATERS OF THE THUMB.
LIKEWISE...THESE SAME LOCATIONS WILL SEE SIGNIFICANT WAVE HEIGHTS
BUILD INTO THE 6 TO 8 FOOT RANGE DURING THIS TIME PERIOD WITH THE
REMAINING NEARSHORE ZONES GENERALLY EXPERIENCING SIG WAVES OF 6 FEET
OR LESS. WINDS WILL EASE BY SUNDAY EVENING FOLLOWED BY SUBSIDING
WAVES BY LATE SUNDAY NIGHT. SMALL CRAFT ADVISORIES HAVE BEEN ISSUED
ACCORDINGLY FOR ALL NEARSHORE ZONES OF LAKE HURON. A REDUCED FETCH
FOR THE SOUTHERN WATERS OF LAKE SAINT CLAIR AND MICHIGAN WATERS OF
LAKE ERIE WILL LIMIT THEIR SIG WAVES TO AROUND 3 FEET.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS
FROM PORT AUSTIN TO PORT SANILAC...FROM 2 AM SUNDAY TO 10 PM
SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT SANILAC TO PORT
HURON...FROM 5 AM SUNDAY TO 4 AM MONDAY.
SMALL CRAFT ADVISORY...INNER SAGINAW BAY...FROM 5 AM SUNDAY TO 4 PM
SUNDAY.
LAKE ST CLAIR...
SMALL CRAFT ADVISORY...FROM 8 AM SUNDAY TO 8 PM SUNDAY.
MI WATERS OF LAKE ERIE...
SMALL CRAFT ADVISORY...FROM 8 AM SUNDAY TO 8 PM SUNDAY.
&&
$$
AVIATION.....MR
SHORT TERM...CB
LONG TERM....HLO
MARINE.......CB
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
144 AM EDT FRI SEP 6 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 410 PM EDT THU SEP 5 2013
WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL FLOW
THROUGH THE GREAT LAKES BETWEEN A TROUGH OVER NE CANADA AND A RIDGE
FROM COLORADO INTO THE WRN PLAINS. THE MAIN UPSTREAM SHORTWAVE
TROUGH OF INTEREST WAS MOVING INTO WEST CENTRAL SASK. AT THE
SFC...HIGH PRES WAS CENTERED OVER MI AND THE WRN GREAT LAKES
BRINGING CLEAR SKIES AND LIGHT WINDS TO THE REGION.
TONIGHT...MAINLY CLEAR SKIES THIS EVENING ARE EXPECTED TO GIVE WAY
TO INCREASING MID/HIGH CLOUDS LATE. TEMPS MAY DROP OFF QUICKLY AFTER
SUNSET BUT WITH INCREASING SW FLOW OVERNIGHT...TEMPS ARE EXPECTED TO
ONLY DROP TO AROUND CENTRAL 50 AND BECOME STEADY OR SLOWLY RISING IN
THE MID TO UPPER 50S WEST.
FRIDAY...THE SASK SHRTWV IS EXPECTED TO SLIDE JUST NORTH OF LAKE
SUPERIOR. HOWEVER...925-700 MB THETA-E ADVECTION AHEAD OF THIS
FEATURE AND ASSOCIATED 310K ISENTROPIC LIFT WILL SUPPORT SCT ELEVATED
SHRA/TSRA INTO N AND W LAKE SUPERIOR BY LATE MORNING THAT MAY SPREAD
INTO THE CNTRL AND EAST DURING THE AFTERNOON. THERE IS STILL ENOUGH
UNCERTAINTY WITH MDLS DIFFERING ON TIMING/POSITION OF THE PCPN TO
KEEP JUST CHANCE POPS. ALTHOUGH MUCAPE VALUES TO AROUND 1K J/KG
RANGE MAY SUPPORT SOME STRONGER STORMS...THE GREATER INSTABILITY
WITH MLCAPES OF 1000-1500 J/KG IS EXPECTED TO REMAIN UPSTREAM OVER
MN. EVEN WITH INCREASING CLOUDS AND PCPN POSSIBLE DURING THE
AFTERNOON...HIGH TEMPS SHOULD CLIMB INTO THE LOWER 80S.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 410 PM EDT THU SEP 5 2013
MAIN FCST CONCERNS IN THE LONGER TERM REVOLVE ARND POPS ON FRI
NGT/SAT ASSOCIATED WITH PASSAGE OF SHRTWVS IN NW FLOW ALF BTWN THE
MEAN TROF OVER QUEBEC AND RIDGE IN THE PLAINS. FOCUS FOR LATER IN
THE WEEKEND TURNS TOWARD HI PRES BLDG INTO THE UPR LKS.
FRI NGT/SAT...A SHRTWV EMBEDDED IN THE NW FLOW ALF IS PROGGED TO
PASS NEAR THE UPR LKS IN THE EVNG...SO EXPECT THE BEST CHC OF
SHRA/TS TO BE IN THE EVNG WHEN ACCOMPANYING PVA INTERACTS WITH AXIS
OF HIER H85 THETA E. MID LVL DRYING/NEGATIVE H85 THETA E AVCTN IN
THE WAKE OF THIS INITIAL SHRTWV PASSAGE WL THEN RESULT IN
DIMINISHING POPS NW-SE THRU SAT MRNG...BUT APRCH OF ANOTHER SHRTWV
IN THE NW FLOW ALF WARRANTS AT LEAST A SCHC OF LINGERING SHRA. THE
12Z GFS AND ESPECIALLY THE 00Z CNDN MODELS ARE SLOWER/STRONGER THAN
THE BULK OF THE OTHER GUIDANCE WITH THIS TRAILING
DISTURBANCE...LINGERING DEEP LYR QVECTOR CNVGC AND QPF THRU MOST OF
THE DAY ON SAT...SO RETAINED SOME LO CHC POPS ESPECIALLY OVER THE
SCENTRAL THRU THE ENTIRE DAY.
SAT NGT THRU SUN...CNDN HI PRES UNDER CONFLUENT NW FLOW ALF BTWN THE
TROF IN QUEBEC/RDG IN THE PLAINS IS PROGGED TO SHIFT FM MANITOBA AT
00Z SUN TO OVER LK SUP SUN AFTN. UNDER LARGER SCALE SUBSIDENCE AND
PWAT FCST AOB 0.50 INCH...DRY WX WL PREVAIL. THE ONLY CONCERN IS
WHETHER THERE WL BE ANY LO CLDS AT LEAST FOR A TIME NEAR LK SUP WITH
UPSLOPE NNE FLOW UNDER SHARP SUBSIDENCE INVRN H85-9 IN ADVANCE OF
THE INCOMING SFC HI AS SUGGESTED BY THE 06Z AND 12Z GFS RUNS. GIVEN
LARGE SCALE ACYC LLVL FLOW...DRY NATURE OF INCOMING AIRMASS AND
MARGINAL CHILL OF THIS AIRMASS FOR LK CLDS /H925 TEMPS NO LOWER THAN
6-7C OVER THE E HALF COMPARED TO OPEN WATER TEMPS 14-15C/...
RESTRICTED FCST OF SCT-BKN LO CLDS TO THE HIER TERRAIN OF THE
NCENTRAL EARLY SUN MRNG PER THE MORE PESSIMISTIC GFS FCST SDNGS AND
BEFORE DAYTIME HEATING WOULD MIX THESE CLDS OUT ON SUN AFTN. TEMPS
ON SUN MRNG/AFTN WL BE COOLER THAN THE DAY BEFORE WITH H85 TEMPS
FCST BTWN 5-10C DURING THIS PERIOD. EXPECT THE LOWEST MIN TEMPS ON
SUN MRNG OVER THE INTERIOR W...WITH NNE FLOW OFF LK SUP KEEPING
AREAS NEAR THE SHORE WARMER.
SUN NGT...AS SFC HI PRES DRIFTS OVER NY STATE BY 12Z SUN...A RETURN
SLY FLOW OF WARMER/MOISTER AIR BTWN THIS FEATURE AND A SHRTWV/
ACCOMPANYING SFC LO MOVING INTO THE NRN PLAINS WL DVLP OVER THE UPR
LKS. SO EXPECT AT LEAST SOME INCRS IN CLDS AND A WARMER OVERNGT.
RESTRICTED POPS TO THE FAR WRN CWA GIVEN MODEL QPF/LINGERING LLVL
DRY AIR OVER MOST OF THE CWA.
MON INTO TUE...AS SHRTWV IN THE NRN PLAINS AND ATTENDANT SFC LO PRES/
WARM FNT MOVE TOWARD THE UPR LKS...EXPECT SHRA/TS CHCS TO INCRS OVER
THE CWA. NOT SURPRISINGLY...THE EXTENDED MODELS DISAGREE ON THE
EXACT TRACK OF THE SFC LO/WARM FNT AND AXIS OF HIER QPF. THE 12Z AND
ESPECIALLY THE 00Z CNDN MODELS ARE FARTHER N WITH THE SFC LO TRACK/
WARM FNT AND FCSTS THE BULK OF ANY ACCOMPANYING SHRA/TS TO REMAIN N
OF UPR MI WHILE THE 06Z GFS FCSTS HEAVY PCPN WITH THE SFC LO
TRACKING E THRU THE CWA OVER THE WARM FNT ON MON INTO EARLY TUE. THE
RESULT OF THIS SCENARIO WOULD BE A WARM SUMMER-LIKE DAY WITH A GOOD
DEAL OF SUNSHINE AND H85/SFC TEMPS NEAR 20C/WELL INTO THE 80S AWAY
FM LK MODERATION IN LLVL SW FLOW. SHRA/TS WITH HEAVY RA/PSBL SEVERE
TS WOULD BE THE RESULT IF THE GFS MODEL VERIFIES. THE 12Z GFS/00Z
ECWMF RUNS ARE A COMPROMISE BTWN THOSE TWO CAMPS AND ALSO INDICATE
THE POTENTIAL FOR SEVERE TS WITH FCST H85 TEMPS UP TO 20C AND SSI AS
LO AS -3 TO -4C UNDER STRONGER H5 FLOW. GIVEN THESE UNCERTAINTIES...
MAINTAINED CONSENSUS FCST FOR NOW.
EXTENDED...AS AN UPR TROF DEEPENS INTO THE GREAT LKS ON WED BEHIND
DEPARTING SHRTWV RESPONSIBLE FOR THE MON/TUE POPS...EXPECT SHRA/TS
CHCS TO PERSIST. EXPECT COOLER/DRIER WX TO SPREAD TO THE E NEXT
THU/FRI AS HI PRES BLDS TOWARD THE PLAINS/WRN GRT LKS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 143 AM EDT FRI SEP 6 2013
EXPECT VFR CONDITIONS AND LIGHT WINDS EARLY THIS MORNING WITH MID
CLOUDS THICKENING AT CMX. ANY SHOWERS AND THUNDERSTORMS ARE EXPECTED
TO HOLD OFF UNTIL THIS AFTERNOON. THE BETTER CHC FOR SHRA/TSRA WILL
BE AT KCMX AND KSAW MID TO LATE AFTERNOON INTO THE EVENING HOURS JUST
AHEAD OF COLD FRONT WORKING THROUGH REGION. MENTIONED ONLY VICINITY
SHRA AT KIWD AS THEY WILL BE FARTHER REMOVED FROM BEST FORCING FOR
SHRA/TSRA ACTIVITY.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 410 PM EDT THU SEP 5 2013
EXPECT SW WINDS UP TO 20-25 KTS ON FRI UNDER SHARPENING PRES
GRADIENT AHEAD OF INCOMING LO PRES TROUGH. FOLLOWING THE PASSAGE OF
A COLD FRONT ON SAT...WINDS WILL VEER TO THE N-NE AND REMAIN UP TO
20 KTS INTO SUN IN ADVANCE OF HI PRES BUILDING TOWARD THE GREAT
LAKES. A RELATIVELY WEAK PRES GRADIENT AND/OR HI OVERWATER STABILITY
WILL THEN DOMINATE ON SUN INTO TUE...RESULTING IN WINDS UNDER 20 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KC
AVIATION...JLA/VOSS
MARINE...KC
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
413 PM CDT FRI SEP 6 2013
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 145 PM CDT FRI SEP 6 2013
CONFIDENCE LEVEL REMAINS LOW FOR ANY CHGS IN THE SHORT
TERM...ESPECIALLY TONIGHT AS A WEAK COOL FRONT MOVES SOUTHEAST
ACROSS THE REGION...AND STALLS SOUTH OF THE MINNESOTA BORDER
SATURDAY. THE MAIN DILEMMA TONIGHT IS WHETHER SHRA/TSRA DEVELOP
THIS EVENING ALONG A FAIRLY GOOD MOISTURE PLUME THAT IS EVIDENT
ACROSS THE SE FAR FA...WHERE EARLIER SHRA DISSIPATED. IN
ADDITION...AN AREA OF SHRA AND ISOLD TSRA HAVE BEEN MOVING
EASTWARD ACROSS THE DAKOTAS WHICH MAY ALLOW FOR SOME -SHRA ACROSS
WESTERN MN THIS EVENING. HOWEVER...WESTERN MN HAS A GOOD AREA OF
DRYING AT MID LEVELS WHICH SHOULD LIMIT THE CONVECTION POTENTIAL.
THE BEST POTENTIAL REMAINS ACROSS WC WI WHERE CURRENT MLCIN/S ARE
WEAKEST ACROSS THIS REGION ALONG WITH MODEST CAPES. ONLY LIMITING
FACTOR IS THE ORIENTATION OF THE LLJ AND MOISTURE ADVECTION WHICH
IS ACROSS NE WI. FORECASTERS WILL NEED TO CLOSELY WATCH
AFTERNOON/EARLY EVENING CUMULUS FIELD AND HOW IT MAY BUILD TO THE
SW ACROSS WC WI/EC MN. OTHERWISE...THE WEAK COOL FRONT WILL MOVE
SOUTHEAST ACROSS MN BY SATURDAY MORNING. ALTHOUGH DEW PTS WILL
LOWER THROUGHOUT THE DAY ON SATURDAY...THE MAIN CAA WON/T DEVELOP
UNTIL LATE IN THE AFTN/EVENING WHICH MAY ALLOW FOR ANOTHER DAY OF
90S IN THE SOUTH/SW FA. WILL LEAVE CURRENT HIGHS ON SATURDAY THE
SAME BASED ON THIS SCENARIO.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 410 PM CDT FRI SEP 6 2013
THE PREVAILING PATTERN OF RIDGING IN THE WRN CONUS AND TROFFING IN
THE ERN CONUS WILL BREAK DOWN SUN THROUGH MON AS THE RIDGE
FLATTENS AND SHIFTS E...ALLOWING A FRONTAL SYSTEM TO IMPACT THE
AREA SUN NIGHT THRU MON NIGHT. AT THE SFC...HIGH PRES FROM
W-CENTRAL CANADA WILL DIVE SE THROUGH THE GREAT LAKES WHILE AN
AREA OF LOW PRES GATHERS STRENGTH OVER WY/MT SAT NIGHT INTO SUN.
THIS SYSTEM WILL THEN TRAVERSE ENE THRU SD INTO NRN MN SUN NIGHT
THRU MON WHILE THE UPPER LEVEL PATTERN BECOMES LESS MERIDIONAL AND
MORE ZONAL. A WEAK CDFNT DROPPING THRU THE CWFA SAT WILL RETURN N
AS A WMFNT ON SUN...HELPING AID NOT ONLY AN INCREASE IN THE
MOISTURE COLUMN BUT ALSO AN INCREASE IN TEMPS/INSTABILITY. THOUGH
THE MAIN FOCUS FOR PRECIP SUN NIGHT INTO MON WILL BE N OF THE WFO
MPX CWFA...REMNANTS OF POTENTIAL TSTM CLUSTERS AND/OR MCS
DEVELOPMENT LOOK TO DROP INTO NRN PORTIONS OF THE WFO MPX CWFA BUT
BECAUSE OF GREATER UNCERTAINTY...HAVE DROPPED POPS OUT OF THE
LIKELY CATEGORY AND CAPPED POPS IN THE HIGH CHC RANGE. THE
SECONDARY CDFNT OF THIS SYSTEM WILL DROP THROUGH MON NIGHT INTO
EARLY TUE...BUT THE SFC LOW WILL BECOME LARGELY STRETCHED OUT
WHILE UPPER LEVEL SUPPORT IS RATHER WEAK. THIS WOULD MAKE MON
NIGHT INTO EARLY TUE THE END OF POTENTIAL PRECIP FROM THIS SYSTEM.
THE RIDGE WEST/TROF EAST PATTERN THEN REGAINS CONTROL STARTING TUE
NIGHT AND LINGERS THROUGH FRIDAY. HOWEVER...THOUGH THE UPPER LEVEL
PATTERN WOULD NORMALLY BE CONDUCIVE TO WARMING...THE PRONOUNCED NW
FLOW ALOFT THAT WILL NOT WAVER MUCH WILL BRING IN PIECES OF
MODIFIED CANADIAN AIR TO THE REGION. H85 TEMPS THAT WILL STAY IN
THE 16-20 DEG C RANGE SAT AND SUN...THEN JUMP TO THE MID 20S ON
MON...WILL STEADILY DROP AS THE WEEK PROGRESSES...EVEN POTENTIALLY
HITTING THE SINGLE DIGITS BY THE END OF NEXT WEEK. THIS WILL
TRANSLATE TO THE SFC AS HIGHS ON SUN IN THE MID 70S TO LWR 80S
THAT WILL JUMP TO THE MID 80S TO MID 90S ON MON. ONCE THE
SECONDARY CDFNT DROPS THRU...HIGHS WILL DROP BACK TO THE 70S AND
80S TUE...THEN CONTINUE TO FALL THRU THE WEEK...EVENTUALLY LANDING
IN THE 60S AND 70S BY THE END OF THE WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1231 PM CDT FRI SEP 6 2013
MAIN SHORT TERM AVIATION CONCERN IS WHETHER TSRA/SHRA DEVELOP
ALONG AND JUST AHEAD OF A COOL FRONT EXPECTED TO MOVE ACROSS THE
STATE BY MORNING. THERE REMAINS A SMALL REGION OF THETA-E
ADVECTION AND ASSOCIATED MOISTURE POOLING FROM EARLY MORNING SHRA
ACROSS EC MN INTO WC WI. ALTHOUGH WE HAVE MIXED OUT EARLY THIS
AFTN AND NO CUMULUS HAS FORMED...THIS MAY BE TEMPORARY ONCE
MOISTURE LIFTS THE THE LCL/S BY MID/LATE AFTN. LATEST RAP DOES
SUGGEST A SMALL AREA OF MODEST CAPE WITH WEAKENING CIN FROM EC MN
TO WC WI...WITH AN AREA OF PRECIPITATION DEVELOPING ALONG IT.
ALTHOUGH WE HAVE BEEN DRY AND MODELS HAVE BEEN TOO WET
LATELY...THERE REMAINS SOME CONCERN DO TO THE INCREASING MOISTURE
ADVECTION ALREADY NOTED IN SATELLITE IMAGERY. THEREFORE...WILL
UPDATE 18Z TAFS WITH SCT050 AT MSP/RNH/EAU WITH VCSH OR TEMPO AT
EAU WITH -SHRA DURING THE OVERNIGHT PERIOD. ELSEWHERE...TOO DRY AT
LOW LEVELS TO HAVE ANYTHING OTHER THAN MID LEVEL CLOUD COVER. SFC
WINDS WILL DIE OFF BY SUNSET...THEN BECOME NEARLY CALM
OVERNIGHT...THEN BY SUNRISE SHIFT TO THE NE/ENE AS THE FRONT AND
MIXING BEHIND IT DEVELOPS. SOME BR WILL LIKELY FORM NEAR
RNH/EAU/STC...WITH A CHC OF IFR VSBYS AT RNH/EAU IF PRECIPITATION
DEVELOPS THIS EVENING.
KMSP...MAIN CONCERN IS WHETHER ENOUGH MOISTURE AT LOW LEVELS CAN
OVERCOME THE CIN THIS AFTN AND DEVELOP SHRA/TSRA BY EARLY EVENING.
CONFIDENCE REMAINS TOO LOW FOR ANY MAJOR CHGS. HOWEVER...ENOUGH
CONFIDENCE TO BEGIN TO ADD SCT050...WITH POSSIBLY VCSH BY 00-02Z
IF THE ATMOSPHERE CAN OVERCOME THE CIN. OTHERWISE...NO OTHER
AVIATION CONCERNS WITH WINDS DECREASING BY SUNSET...AND BECOMING
MORE NNE/NE AFT 12Z...AND BEGIN TO GUST SATURDAY AFTN.
/OUTLOOK FOR KMSP/
SAT NIGHT...VFR. ENE WINDS 10 KTS.
SUN...VFR. CHC MVFR TRW LATE. ESE WINDS 10-14 KTS.
MON...VFR. CHC MVFR TRW. S WINDS 8-12 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...JLT
LONG TERM...JPC
AVIATION...JLT
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
203 PM CDT FRI SEP 6 2013
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 145 PM CDT FRI SEP 6 2013
CONFIDENCE LEVEL REMAINS LOW FOR ANY CHGS IN THE SHORT
TERM...ESPECIALLY TONIGHT AS A WEAK COOL FRONT MOVES SOUTHEAST
ACROSS THE REGION...AND STALLS SOUTH OF THE MINNESOTA BORDER
SATURDAY. THE MAIN DILEMMA TONIGHT IS WHETHER SHRA/TSRA DEVELOP
THIS EVENIGN ALONG A FAIRLY GOOD MOISTURE PLUME THAT IS EVIDENT
ACROSS THE SE FAR FA...WHERE EARLIER SHRA DISSIPATED. IN
ADDITION...AN AREA OF SHRA AND ISOLD TSRA HAVE BEEN MOVING
EASTWARD ACROSS THE DAKOTAS WHICH MAY ALLOW FOR SOME -SHRA ACROSS
WESTERN MN THIS EVENING. HOWEVER...WESTERN MN HAS A GOOD AREA OF
DRYING AT MID LEVELS WHICH SHOULD LIMIT THE CONVECTION POTENTIAL.
THE BEST POTENTIAL REMAINS ACROSS WC WI WHERE CURRENT MLCIN/S ARE
WEAKEST ACROSS THIS REGION ALONG WITH MODEST CAPES. ONLY LIMITING
FACTOR IS THE ORIENTATION OF THE LLJ AND MOISTURE ADVECTION
WHICH IS ACROSS NE WI. FORECASTERS WILL NEED TO CLOSELY WATCH
AFTERNOON/EARLY EVENING CUMULUS FIELD AND HOW IT MAY BUILD TO THE
SW ACROSS WC WI/EC MN. OTHERWISE...THE WEAK COOL FRONT WILL MOVE
SOUTHEAST ACROSS MN BY SATURDAY MORNING. ALTHOUGH DEW PTS WILL
LOWER THROUGHOUT THE DAY ON SATURDAY...THE MAIN CAA WON/T DEVELOP
UNTIL LATE IN THE AFTN/EVENING WHICH MAY ALLOW FOR ANOTHER DAY OF
90S IN THE SOUTH/SW FA. WILL LEAVE CURRENT HIGHS ON SATURDAY THE
SAME BASED ON THIS SCENARIO.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 315 AM CDT FRI SEP 6 2013
RIDGING ALOFT WILL DOMINATE THE REGION THROUGH MONDAY WITH AN
UPPER TROUGH MOVING THROUGH TUESDAY AND WEDNESDAY. THE TROUGH IS
THE REMNANTS OF THE CUT-OFF LOW CURRENTLY OVER THE PACIFIC
NORTHWEST. THE GEM/GFS AND ECMWF ARE IN REALLY GOOD AGREEMENT WITH
THE HEIGHT PATTERN ALOFT THROUGH THE EXTENDED PERIOD.
THE MAIN CONCERNS FOR THE LONGER TERM ARE PRECIPITATION CHANCES
SUNDAY NIGHT AND HIGH TEMPERATURES ON MONDAY. A COOL FRONT THAT
MOVES EAST AND SOUTH OF THE FA ON SATURDAY WILL RETURN SUNDAY
NIGHT AS A WARM FRONT. THE FOCUS OF MOISTURE TRANSPORT...
DIFFERENTIAL TEMPERATURE ADVECTION AND DIFFERENTIAL DIVERGENCE
POINT TO AN MCS FORMING OVER THE DAKOTAS AND MOVING ACROSS
NORTHERN MN DURING THE NIGHT. HIGH CHANCE TO LIKELY POPS LOOK
APPROPRIATE ACROSS CENTRAL MN AND PORTIONS OF WEST CENTRAL WI BUT
REALLY WONDER IF ANYTHING AT ALL WILL OCCUR ACROSS SOUTHERN MN.
TRIED TO MINIMIZE POPS IN THE SOUTH AS MUCH AS POSSIBLE AND REMAIN
IN COLLABORATION. THIS LEADS INTO MONDAY WHEN A SOUTHWEST SURFACE WIND
WILL DEVELOP IN THE WAKE OF THE WARM FRONT. 850 MB TEMPERATURES ON
THE GFS AND ECMWF REMAIN CONSISTENT WITH 22-26 DEG C BLASTING
ACROSS THE FA BY MIDDAY. MIX DOWN YIELDS HIGHS IN THE MIDDLE TO
UPPER 90S... WHICH IS CLOSE THE ECMWF MAX TEMP FORECAST. THE EC
WAS THE HIGHEST OF ALL OF THE GUIDANCE. BLENDED THE MIX-DOWN WITH
THE CR EXTEND... WHICH PLACED HIGHS IN THE TWIN CITIES INTO THE LOWER
90S. THIS STILL MAY NOT BE ENOUGH. THE NORTHERN AND EASTERN
PERIPHERIES OF THE CWA ARE MORE PRONE TO SOME CLOUDINESS AND
THEREFORE CUT HIGHS BACK SOME TO STAY IN COLLABORATION WITH OUR
NEIGHBORS. FORTUNATELY... DEW POINTS ARE EXPECTED TO ONLY BE IN
THE MIDDLE 60S ON MONDAY. THIS RESULTS IN HEAT INDICES TO AROUND
95 DEGREES.
THE THREAT FOR SHOWERS AND THUNDERSTORMS INCREASE MONDAY NIGHT AS
THE AFOREMENTIONED TROUGH ALOFT APPROACHES FROM THE WEST ALONG
WITH A COLD FRONT. CAPPING ALOFT WILL GIVE WAY TO HEIGHT FALLS AND
COOLER TEMPERATURES WITH PRETTY GOOD CHANCES FOR RAIN DURING THE NIGHT.
COOLER AND DRIER WEATHER PREVAILS IN THE WAKE OF THE FRONT FROM
TUESDAY THROUGH THURSDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1231 PM CDT FRI SEP 6 2013
MAIN SHORT TERM AVIATION CONCERN IS WHETHER TSRA/SHRA DEVELOP
ALONG AND JUST AHEAD OF A COOL FRONT EXPECTED TO MOVE ACROSS THE
STATE BY MORNING. THERE REMAINS A SMALL REGION OF THETA-E
ADVECTION AND ASSOCIATED MOISTURE POOLING FROM EARLY MORNING SHRA
ACROSS EC MN INTO WC WI. ALTHOUGH WE HAVE MIXED OUT EARLY THIS
AFTN AND NO CUMULUS HAS FORMED...THIS MAY BE TEMPORARY ONCE
MOISTURE LIFTS THE THE LCL/S BY MID/LATE AFTN. LATEST RAP DOES
SUGGEST A SMALL AREA OF MODEST CAPE WITH WEAKENING CIN FROM EC MN
TO WC WI...WITH AN AREA OF PRECIPITATION DEVELOPING ALONG IT.
ALTHOUGH WE HAVE BEEN DRY AND MODELS HAVE BEEN TOO WET
LATELY...THERE REMAINS SOME CONCERN DO TO THE INCREASING MOISTURE
ADVECTION ALREADY NOTED IN SATELLITE IMAGERY. THEREFORE...WILL
UPDATE 18Z TAFS WITH SCT050 AT MSP/RNH/EAU WITH VCSH OR TEMPO AT
EAU WITH -SHRA DURING THE OVERNIGHT PERIOD. ELSEWHERE...TOO DRY AT
LOW LEVELS TO HAVE ANYTHING OTHER THAN MID LEVEL CLOUD COVER. SFC
WINDS WILL DIE OFF BY SUNSET...THEN BECOME NEARLY CALM
OVERNIGHT...THEN BY SUNRISE SHIFT TO THE NE/ENE AS THE FRONT AND
MIXING BEHIND IT DEVELOPS. SOME BR WILL LIKELY FORM NEAR
RNH/EAU/STC...WITH A CHC OF IFR VSBYS AT RNH/EAU IF PRECIPITATION
DEVELOPS THIS EVENING.
KMSP...
MAIN CONCERN IS WHETHER ENOUGH MOISTURE AT LOW LEVELS CAN OVERCOME
THE CIN THIS AFTN AND DEVELOP SHRA/TSRA BY EARLY EVENING.
CONFIDENCE REMAINS TOO LOW FOR ANY MAJOR CHGS. HOWEVER...ENOUGH
CONFIDENCE TO BEGIN TO ADD SCT050...WITH POSSIBLY VCSH BY 00-02Z
IF THE ATMOSPHERE CAN OVERCOME THE CIN. OTHERWISE...NO OTHER
AVIATION CONCERNS WITH WINDS DECREASING BY SUNSET...AND BECOMING
MORE NNE/NE AFT 12Z...AND BEGIN TO GUST SATURDAY AFTN.
/OUTLOOK FOR KMSP/
SAT NIGHT...VFR. ENE WINDS 10 KTS.
SUN...VFR. CHC MVFR TRW LATE. ESE WINDS 10-14 KTS.
MON...VFR. CHC MVFR TRW. S WINDS 8-12 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...JLT
LONG TERM...RAH
AVIATION...JLT
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1248 PM CDT FRI SEP 6 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT FRI SEP 6 2013
COMBINATION OF WEAK WAA AND MOISTURE TRANSPORT IN THE H85-H7 LAYER
OVERNIGHT HAS RESULTED IN AREA OF ACCUS WITH A FEW ISO SHOWERS
MOVING ACROSS SRN MN THROUGH THE NIGHT. HIGH-RES CAMS ALL FAIRLY
SIMILAR WITH AN AREA OF ISO-SCT SHOWERS BLOSSOMING NEAR THE I-35
CORRIDOR FROM THE TWIN CITIES SOUTH NEAR SUNRISE. AFTER
SUNRISE...WHAT LITTLE ACTIVITY THERE IS SHOULD DIMINISH QUICKLY AS
LLJ DRIVING THIS WEAKENS SOME...SO HAVE ANY SMALL POPS MENTIONED
UNTIL 15Z.
IN THE WAKE OF THIS SYSTEM...SW WINDS WILL RESULT IN 925-850 MB
TEMPS INCREASING TO AROUND 22C IN THE EAST AND 26C IN THE WEST.
SIMILAR TEMPERATURES IN THIS LAYER YESTERDAY RESULTED IN HIGHS IN
THE UPPER 80S TO LOWER 90S OUT IN THE DAKOTAS...SO HAVE HIGHS
LOOKING PRETTY MUCH THE SAME FROM EAST TO WEST ACROSS THE MPX AREA
TODAY. THOUGH THESE HIGHS ARE NEARLY 15 DEGREES ABOVE NORMAL...
RECORD HIGHS TODAY SHOULD BE SAFE WITH THE NUMBERS TO BEAT SITTING
AT 95 IN STC...98 AT MSP...AND 100 IN EAU. WITH DEWPS INCREASING
BACK INTO THE MID/UPPER 60S...WILL SEE HEAT INDICES THIS AFTERNOON
PEAKING BACK UP IN THE MID 90S...WITH LOWS OVERNIGHT ONLY FALLING
BACK INTO THE MID 60S AT BEST.
THE TROUGH MENTIONED IN THE SYNOPSIS OUT TO THE WEST WILL EVOLVE
INTO A WEAK COLD FRONT THIS AFTERNOON THAT WILL BEGIN TO WORK ACROSS
THE AREA OVERNIGHT. THE WARM TEMPERATURES MOVING IN TODAY ALOFT WILL
ALSO BRING IN A STRONG CAPPING INVERSION THAT LOOKS TO KEEP THE MN
PORTION OF THE MPX CWA DRY WITH ANY ACTIVITY CONFINED TO THE
PERIPHERY OF THE CAP...WHICH WOULD MEAN ANOTHER NIGHT OF WATCHING
ACTIVITY WORKING FROM NE MN INTO CENTRAL WI. LIKE TONIGHT...WEAK
WARM ADVECTION AND MOISTURE TRANSPORT IN THE H85-H7 LAYER WILL FIND
ITS WAY OVER TO WI OUT AHEAD OF THE FRONT. AS A RESULT...A FEW OF
THE HI-RES CAMS SHOW SOME THUNDERSTORMS WORKING ACROSS WRN WI FRIDAY
NIGHT. HOWEVER...WITH WARM TEMPS ALOFT AND WEAK SHORTWAVE DRIVING
THIS CONVECTION GOING ACROSS LAKE SUPERIOR...CONFIDENCE IS NOT ALL
THAT HIGH THAT SOME MUCH NEEDED RAINS WILL BE SEEN IN THE ERN MPX
CWA SO HAVE ONLY SLIGHT CHANCES MENTIONED AT THIS POINT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 315 AM CDT FRI SEP 6 2013
RIDGING ALOFT WILL DOMINATE THE REGION THROUGH MONDAY WITH AN
UPPER TROUGH MOVING THROUGH TUESDAY AND WEDNESDAY. THE TROUGH IS
THE REMNANTS OF THE CUT-OFF LOW CURRENTLY OVER THE PACIFIC
NORTHWEST. THE GEM/GFS AND ECMWF ARE IN REALLY GOOD AGREEMENT WITH
THE HEIGHT PATTERN ALOFT THROUGH THE EXTENDED PERIOD.
THE MAIN CONCERNS FOR THE LONGER TERM ARE PRECIPITATION CHANCES
SUNDAY NIGHT AND HIGH TEMPERATURES ON MONDAY. A COOL FRONT THAT
MOVES EAST AND SOUTH OF THE FA ON SATURDAY WILL RETURN SUNDAY
NIGHT AS A WARM FRONT. THE FOCUS OF MOISTURE TRANSPORT...
DIFFERENTIAL TEMPERATURE ADVECTION AND DIFFERENTIAL DIVERGENCE
POINT TO AN MCS FORMING OVER THE DAKOTAS AND MOVING ACROSS
NORTHERN MN DURING THE NIGHT. HIGH CHANCE TO LIKELY POPS LOOK
APPROPRIATE ACROSS CENTRAL MN AND PORTIONS OF WEST CENTRAL WI BUT
REALLY WONDER IF ANYTHING AT ALL WILL OCCUR ACROSS SOUTHERN MN.
TRIED TO MINIMIZE POPS IN THE SOUTH AS MUCH AS POSSIBLE AND REMAIN
IN COLLABORATION. THIS LEADS INTO MONDAY WHEN A SOUTHWEST SURFACE WIND
WILL DEVELOP IN THE WAKE OF THE WARM FRONT. 850 MB TEMPERATURES ON
THE GFS AND ECMWF REMAIN CONSISTENT WITH 22-26 DEG C BLASTING
ACROSS THE FA BY MIDDAY. MIX DOWN YIELDS HIGHS IN THE MIDDLE TO
UPPER 90S... WHICH IS CLOSE THE ECMWF MAX TEMP FORECAST. THE EC
WAS THE HIGHEST OF ALL OF THE GUIDANCE. BLENDED THE MIX-DOWN WITH
THE CR EXTEND... WHICH PLACED HIGHS IN THE TWIN CITIES INTO THE LOWER
90S. THIS STILL MAY NOT BE ENOUGH. THE NORTHERN AND EASTERN
PERIPHERIES OF THE CWA ARE MORE PRONE TO SOME CLOUDINESS AND
THEREFORE CUT HIGHS BACK SOME TO STAY IN COLLABORATION WITH OUR
NEIGHBORS. FORTUNATELY... DEW POINTS ARE EXPECTED TO ONLY BE IN
THE MIDDLE 60S ON MONDAY. THIS RESULTS IN HEAT INDICES TO AROUND
95 DEGREES.
THE THREAT FOR SHOWERS AND THUNDERSTORMS INCREASE MONDAY NIGHT AS
THE AFOREMENTIONED TROUGH ALOFT APPROACHES FROM THE WEST ALONG
WITH A COLD FRONT. CAPPING ALOFT WILL GIVE WAY TO HEIGHT FALLS AND
COOLER TEMPERATURES WITH PRETTY GOOD CHANCES FOR RAIN DURING THE NIGHT.
COOLER AND DRIER WEATHER PREVAILS IN THE WAKE OF THE FRONT FROM
TUESDAY THROUGH THURSDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1231 PM CDT FRI SEP 6 2013
MAIN SHORT TERM AVIATION CONCERN IS WHETHER TSRA/SHRA DEVELOP
ALONG AND JUST AHEAD OF A COOL FRONT EXPECTED TO MOVE ACROSS THE
STATE BY MORNING. THERE REMAINS A SMALL REGION OF THETA-E
ADVECTION AND ASSOCIATED MOISTURE POOLING FROM EARLY MORNING SHRA
ACROSS EC MN INTO WC WI. ALTHOUGH WE HAVE MIXED OUT EARLY THIS
AFTN AND NO CUMULUS HAS FORMED...THIS MAY BE TEMPORARY ONCE
MOISTURE LIFTS THE THE LCL/S BY MID/LATE AFTN. LATEST RAP DOES
SUGGEST A SMALL AREA OF MODEST CAPE WITH WEAKENING CIN FROM EC MN
TO WC WI...WITH AN AREA OF PRECIPITATION DEVELOPING ALONG IT.
ALTHOUGH WE HAVE BEEN DRY AND MODELS HAVE BEEN TOO WET
LATELY...THERE REMAINS SOME CONCERN DO TO THE INCREASING MOISTURE
ADVECTION ALREADY NOTED IN SATELLITE IMAGERY. THEREFORE...WILL
UPDATE 18Z TAFS WITH SCT050 AT MSP/RNH/EAU WITH VCSH OR TEMPO AT
EAU WITH -SHRA DURING THE OVERNIGHT PERIOD. ELSEWHERE...TOO DRY AT
LOW LEVELS TO HAVE ANYTHING OTHER THAN MID LEVEL CLOUD COVER. SFC
WINDS WILL DIE OFF BY SUNSET...THEN BECOME NEARLY CALM
OVERNIGHT...THEN BY SUNRISE SHIFT TO THE NE/ENE AS THE FRONT AND
MIXING BEHIND IT DEVELOPS. SOME BR WILL LIKELY FORM NEAR
RNH/EAU/STC...WITH A CHC OF IFR VSBYS AT RNH/EAU IF PRECIPITATION
DEVELOPS THIS EVENING.
KMSP...
MAIN CONCERN IS WHETHER ENOUGH MOISTURE AT LOW LEVELS CAN OVERCOME
THE CIN THIS AFTN AND DEVELOP SHRA/TSRA BY EARLY EVENING.
CONFIDENCE REMAINS TOO LOW FOR ANY MAJOR CHGS. HOWEVER...ENOUGH
CONFIDENCE TO BEGIN TO ADD SCT050...WITH POSSIBLY VCSH BY 00-02Z
IF THE ATMOSPHERE CAN OVERCOME THE CIN. OTHERWISE...NO OTHER
AVIATION CONCERNS WITH WINDS DECREASING BY SUNSET...AND BECOMING
MORE NNE/NE AFT 12Z...AND BEGIN TO GUST SATURDAY AFTN.
/OUTLOOK FOR KMSP/
SAT NIGHT...VFR. ENE WINDS 10 KTS.
SUN...VFR. CHC MVFR TRW LATE. ESE WINDS 10-14 KTS.
MON...VFR. CHC MVFR TRW. S WINDS 8-12 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SYNOPSIS...MPG
SHORT TERM...MPG
LONG TERM...RAH
AVIATION...JLT
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1005 PM CDT SAT SEP 7 2013
.SYNOPSIS...
ISSUED AT 319 PM CDT SAT SEP 7 2013
H5 ANALYSIS THIS MORNING HAS LOW PRESSURE CENTERED OVER
EASTERN WASHINGTON STATE WITH HIGH PRESSURE OVER NWRN KS. RIDGING
EXTENDED NORTH OF THIS HIGH INTO THE DAKOTAS. TROUGHING CONTINUED
ACROSS EASTERN CANADA INTO NEW ENGLAND. AT THE SURFACE...A WEAK COOL
FRONT HAS PUSHED INTO WESTERN AND NORTH CENTRAL NEBRASKA AND WAS
POSITIONED ROUGHLY ALONG INTERSTATE 80 FROM LINCOLN TO NORTH PLATTE.
THIS FRONTAL BOUNDARY HAS BEEN ENHANCED BY DECAYING CONVECTION AND
HAS ACTUALLY BEEN PUSHED FARTHER SOUTH THAN THE MODELS INDICATED
YESTERDAY. TEMPERATURES AS OF 3 PM CDT RANGED FROM THE UPPER 80S IN
THE NORTHEASTERN CWA...TO AROUND 100 IN THE SOUTHWEST.
&&
.UPDATE...
ISSUED AT 1005 PM CDT SAT SEP 7 2013
POPS HAVE BEEN REMOVED FOR THE OVERNIGHT FORECAST. THERE IS WAY
TOO MUCH DRY AIR IN THE MID LEVELS TO SUPPORT STORM DEVELOPMENT
AND EVEN THE HRRR HAS GONE SILENT DEVELOPING ANY CONVECTION. THE MCS ACROSS
SD PROBABLY WILL NOT AFFECT THE FCST AREA OVERNIGHT SO IT LOOKS
LIKE A DRY FORECAST OVERNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 319 PM CDT SAT SEP 7 2013
MODELS INDICATE A WEAK DISTURBANCE TOPPING THE CENTRAL
PLAINS RIDGE LATER THIS EVENING ALLOWING FOR A ISOLATED MENTION OF
STORM DEVELOPMENT. THE MOST LIKELY SCENARIO INVOLVES STORMS FIRING
OFF THE HIGHER TERRAIN OF EASTERN WYOMING/WESTERN SOUTH DAKOTA LATE
THIS AFTERNOON...THEN DRIFTING SOUTHEAST OVERNIGHT ACROSS NORTH
CENTRAL NEBRASKA AND PORTIONS OF THE NORTHERN SANDHILLS. THUS WILL
MAINTAIN A SLIGHT CHANCE MENTION IN THIS AREA FOR NOW. ANOTHER
ABNORMALLY HOT DAY IS IN STORE FOR SUNDAY ACROSS MUCH OF WESTERN
NEBRASKA. HIGH TEMPERATURES WILL TOP IN THE MID 90S TO NEAR THE
CENTURY MARK FOR MOST LOCATIONS SAVE NORTH CENTRAL NEBRASKA WHERE A
GREATER SOUTHEASTERLY COMPONENT TO THE LOWER TROPOSPHERIC FLOW WILL
USHER IN SLIGHTLY COOLER TEMPERATURES. OTHERWISE PRECIPITATION
CHANCES WILL BE LIMITED TO FAR NORTHWESTERN PORTIONS OF THE CWA LATE
SUNDAY AS THE UPPER RIDGE AXIS SHIFTS SLIGHTLY TO THE EAST AND A
TROUGH DEEPENS OVER THE NORTHERN ROCKIES. A COLD FRONT WILL DROP
SOUTH THROUGH THE DAKOTAS AND APPROACH NW NEBRASKA BY LATE
AFTERNOON. THIS FRONT SHOULD PROVIDE A FOCUS FOR STORM DEVELOPMENT
WEST AND NORTH OF THE CWA BUT REMAIN REMOVED FROM THE FORECAST AREA.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 319 PM CDT SAT SEP 7 2013
SUNDAY NIGHT THROUGH TUESDAY...THE MAIN FORECASTING
CHALLENGE IS COLD FRONTAL TIMING MONDAY AFTERNOON/EVENING AND
ASSOCIATED PRECIPITATION CHANCES. ON SUNDAY NIGHT...A SEMISTATIONARY
FRONT WILL SLOWLY TRACK FROM THE WESTERN NEBRASKA PANHANDLE...INTO
THE EASTERN NEBRASKA PANHANDLE. TSRAS WILL CONTINUE INVOF OF THE
FRONT SUNDAY EVENING AND ARE NOT EXPECTED TO PERSIST INTO THE
OVERNIGHT HRS...AS THE BEST UPPER LEVEL SUPPORT CONTINUES OVER THE
WESTERN DAKOTAS AND NERN WYOMING. ON MONDAY...AN UPPER LEVEL TROUGH
OF LOW PRESSURE WILL MIGRATE ACROSS SRN SASKATCHEWAN...FORCING THE
COLD FRONT THROUGH THE FORECAST AREA BY LATE MONDAY AFTERNOON. THE
NAM AND GFS HAVE COME IN SLIGHTLY FASTER WITH THE FRONTAL TIMING TDY
COMPARED TO YESTERDAY...AND TRENDED MAX TEMPS DOWNWARD FROM THE
INHERITED FCST. LOW PRECIPITATION CHANCES WILL ACCOMPANY THE FRONTAL
PASSAGE...HOWEVER...HIGHER POPS ARE EXPECTED INTO MONDAY
EVENING...AS MID LEVEL FRONTOGENESIS INCREASES ACROSS THE SANDHILLS
INTO NORTHEASTERN PORTIONS OF THE FORECAST AREA. THIS MID LEVEL
FRONTOGENESIS WILL SHIFT SLOWLY SOUTH INTO SOUTHWESTERN NEBRASKA
OVERNIGHT INTO TUESDAY MORNING WITH THE CORRIDOR OF HIGHEST POPS
SHIFTING ACCORDINGLY.
TUESDAY NIGHT THROUGH SATURDAY...THE FRONTAL BOUNDARY WILL DROP
SOUTH INTO KANSAS STALLING ACROSS CENTRAL OR NORTHERN KANSAS TUESDAY
NIGHT INTO WEDNESDAY. AS WAS THE CASE YESTERDAY...LOCATION OF THE
FRONT...STILL IN SOME DOUBT WITH THE GFS FURTHER SOUTH WITH THIS
FEATURE COMPARED TO THE LATEST 12Z ECMWF. REGARDLESS OF MODEL
CHOICE...DECIDED TO CONFINE POPS TO THE SRN THIRD OF THE FORECAST
AREA WEDNESDAY AND WEDNESDAY NIGHT. BY THURSDAY...THE FRONT...WILL
SHIFT NORTH AS A WARM FRONT AS HIGH AMPLITUDE RIDGING BUILDS INTO
THE CENTRAL CONUS. PRECIPITATION CHANCES WILL SHIFT NORTH ALONG THE
FRONT THURSDAY INTO FRIDAY WITH DRY CONDS EXPECTED FRIDAY NIGHT INTO
SATURDAY. TEMPERATURES ON WEDNESDAY AND THURSDAY...WILL BE IN THE
UPPER 70S TO AROUND 80...WITH HIGHS REBOUNDING BACK INTO THE 80S FOR
FRIDAY AND SATURDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 613 PM CDT SAT SEP 7 2013
THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS EVENING ALONG THE WARM
FRONT DRAPED FROM KCDR TO KTIF/KLBF TO KLXN. ACTIVITY SHOULD BE
SCATTERED ACROSS SHERIDAN COUNTY AND ISOLATED FARTHER SOUTH AND EAST.
A CLUSTER OF STORMS COULD ORGANIZE ACROSS SHERIDAN COUNTY AND MOVE
EAST TOWARD KVTN LATER THIS EVENING. IT IS UNCERTAIN WHETHER THESE
STORMS WILL AFFECT KVTN DIRECTLY. OTHERWISE THE STORM ACTIVITY
SHOULD DISSIPATE BY 09Z AROUND KONL/KANW.
MORE ISOLATED STORM DEVELOPMENT IS POSSIBLE LATE SUNDAY AFTERNOON
AROUND KVTN-KBBW ASSOCIATED WITH A WARM FRONT LIFTING NORTH.
&&
.FIRE WEATHER...
ISSUED AT 321 PM CDT SAT SEP 7 2013
MODEL GUIDANCE CONTINUE TO INDICATE MINIMUM RELATIVE HUMIDITY OF 20
PERCENT OR LESS SUNDAY AFTERNOON FOR FIRE ZONES
210...219...SOUTHERN/CENTRAL HALF OF ZONE 204...AND WESTERN PORTIONS
OF ZONE 206. TEMPERATURES THERE WILL RISE ONCE AGAIN TO NEAR 100
DEGREES WITH DEW POINTS FALLING INTO THE UPPER 40 TO LOW 50 DEGREE
RANGE. WINDS WILL BE STRONG AND FROM THE SOUTH WITH GUST POTENTIAL
OF 25 MPH OR GREATER ACROSS MUCH OF WESTERN NEBRASKA TOMORROW
AFTERNOON. FUELS MAY BE A LIMITING FACTOR HOWEVER AS THEY CONTINUE
TO CURE. SOME FIRE SPREAD IS POSSIBLE BUT WIDESPREAD LARGE/EXTREME
GROWTH IS NOT ANTICIPATED YET.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CDC
SYNOPSIS...CLB
SHORT TERM...JACOBS
LONG TERM...CLB
AVIATION...CDC
FIRE WEATHER...JACOBS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
620 PM EDT FRI SEP 6 2013
.SYNOPSIS...
CANADIAN HIGH PRESSURE WILL DROP ACROSS THE AREA THIS WEEKEND
THEN OFFSHORE BY LATE SUNDAY. A WEAK COLD FRONT WILL DISSIPATE
OVER THE REGION LATE MONDAY...FOLLOWED BY HIGH PRESSURE THROUGH
MID-WEEK. A COLD FRONT IS EXPECTED TO CROSS THE AREA NEXT FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 615 PM FRIDAY...THE FORECASTS HAS BEEN UPDATED A LITTLE EARLY
TO ACCOUNT FOR A CLUSTER OF THUNDERSTORMS MOVING SOUTHWESTWARD DOWN
THE COAST OF NORTH CAROLINA...NOW APPROACHING SURF CITY. THIS
ACTIVITY IS ROOTED WITHIN A NARROW ZONE OF FAIRLY SUBSTANTIAL
SURFACE-BASED INSTABILITY (CAPE NEARLY 2000 J/KG) RIGHT ALONG THE
COAST WHERE DEWPOINTS HAVE RECOVERED TO 70-72 DEGREES DUE TO THE
AFTERNOON SEABREEZE. ON THE WEST (INLAND) SIDE OF THE SEABREEZE
WHERE DEWPOINTS ARE 7-10 DEGREES LOWER THERE IS NEGLIGIBLE
SURFACE-BASED CAPE AND VIRTUALLY NO CHANCE OF PRECIPITATION THIS
EVENING.
THE LATEST THREE HRRR RUNS SHOW THERE IS POTENTIAL FOR THIS
CONVECTION TO CONTINUE ALL THE WAY DOWN TO SOUTHPORT. 0-6 KM BULK
SHEAR IS NEAR 30 KNOTS WHICH IS SUPPORTING THE MULTICELLULAR
CHARACTERISTICS WE ARE OBSERVING. PRECIPITABLE WATER ONLY AROUND 1.3
INCHES...KEPT LOW BY ALL THE DRY AIR IN THE MID LEVELS...IS
OFFSETTING WHAT COULD BE A SERIOUS FLOODING THREAT GIVEN THE SLOW
OBSERVED STORM MOTION. I HAVE INCREASED FORECAST POPS ALONG THE CAPE
FEAR COASTLINE THROUGH ABOUT 02Z...WITH CHANCES FOR PRECIPITATION
DROPPING BELOW MENTIONABLE THRESHOLDS BY MIDNIGHT EVERYWHERE ON
LAND.
NO SIGNIFICANT CHANGES HAVE BEEN MADE TO OTHER FORECAST VARIABLES AT
THIS TIME. PREVIOUS DISCUSSION FROM 300 PM FOLLOWS...
ONE ONLY NEEDS TO LOOK AT THE VISIBLE
SATELLITE IMAGERY COMBINED WITH SURFACE OBS THIS AFTN TO UNDERSTAND
THE SYNOPTIC ENVIRONMENT. TEMPS IN THE UPPER 80S BUT WITH ONLY
SCATTERED SHALLOW CU DEVELOPMENT IS A CLEAR INDICATOR OF DRY HIGH
PRESSURE BUILDING INTO THE AREA. THIS IS BEHIND A COLD FRONT WHICH
HAS SUNK WELL SOUTH OF THE CWA...AND THIS HIGH PRESSURE WILL
CONTINUE TO RIDGE DOWN THE COAST THROUGH TONIGHT. WHILE SURFACE HIGH
PRESSURE WILL ACT TO INHIBIT MUCH CONVECTION TODAY...MID-LEVEL
SHORTWAVE ROTATING AROUND LONGWAVE TROUGH HAS THE POTENTIAL TO
CREATE SOME ISOLATED SHOWERS THIS EVENING AND TONIGHT.
HIGH RES GUIDANCE (WRF/HRRR) CONTINUES TO SUGGEST THAT SCATTERED
SHOWERS WILL DEVELOP NORTH OF THE LOCAL AREA THIS EVENING AND ADVECT
SOUTH INTO THE NORTHERN ZONES TONIGHT. HAVE NOTICED THAT THESE
MODELS ARE INITIALIZING "HOT" HOWEVER...AND THE CONVECTION PROGGED
TO BE ONGOING AT THE PRESENT TIME HAS NOT MATERIALIZED.
STILL...FORECAST SOUNDINGS SUGGEST AMPLE MOISTENING OF THE
1000-800MB LAYER TONIGHT WHICH COMBINED WITH SOME MID-LEVEL FORCING
BENEATH THE SHORTWAVE COULD GENERATE A SHOWER OR TWO...CONFINED TO
THE NORTHEAST PORTIONS OF THE CWA. HAVE CAPPED POP AT
SCHC/ISOLATED...AND SIGNIFICANT DRY AIR ABOVE 700MB WILL INHIBIT
CONVECTION FROM BECOMING STRONG...THUS DO NOT EVEN ANTICIPATE
LIGHTNING. AT THE VERY LEAST...SOME ENHANCED MID LEVEL CLOUD COVER
IS EXPECTED TO DROP SOUTH TO NORTH TONIGHT.
MINS TONIGHT WILL BE A LITTLE TRICKY WITH CONTINUED NE WINDS AND THE
POTENTIALLY ENHANCED CLOUD COVER...ESPECIALLY IN THE N/NE ZONES.
HAVE KEPT MINS SLIGHTLY ABOVE GUIDANCE...SIDING MORE WITH THE WARMER
MET NUMBERS...WHICH HAS GENERALLY PERFORMED BETTER THAN THE MAV THIS
MONTH.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...MAIN FEATURE OF NOTE SATURDAY AND SUNDAY IS
CANADIAN HIGH PRESSURE DROPPING SE ACROSS THE EASTERN CAROLINAS
SATURDAY THEN OFFSHORE BY LATE SUNDAY. NE-E WIND FLOW IN THE
LOWEST SEVERAL THOUSAND FEET OF THE ATMOSPHERE SATURDAY COULD
BRING A MODERATE AMOUNT OF STRATO-CUMULUS SO CERTAINLY DO NOT
WANT TO ADVERTISE ALL OUT "SUNNY". SPOTTY LIGHT SHOWERS CANNOT
BE RULED OUT ALONG THE NORTH COAST AROUND DAYBREAK SATURDAY BUT
WEAK SUBSIDENCE IN WAKE OF AN IMPULSE MOVING SE AND OFFSHORE
SHOULD CONFINE SHOWERS SATURDAY OVER THE 0-20 NM COASTAL WATERS
AND NORTH TO CAPE LOOKOUT. AS THE HIGH MOVES OFFSHORE LATE ON
SUNDAY...A WEAK SHORT-WAVE AND BRIEF SURFACE TROUGH INLAND MAY
TRIP OFF A FEW SHOWERS SUNDAY AFTERNOON AND EVENING. AS THIS
FEATURE DROPS SOUTH OF THE AREA...THE LEADING EDGE OF CANADIAN
HIGH PRESSURE PUSHES A WEAK BACK DOOR FRONT SOUTH INTO OUR NC
ZONES. SUBSIDENCE ALOFT APPEARS TO ACCOMPANY THIS FEATURE WITH
DRY NORTH FLOW ALOFT AND NO MENTIONABLE POPS PLANNED EARLY MON.
SUNDAY MORNING SHOULD BE A FEW DEGREES COOLER THAN SAT MORNING
MAINLY BY VIRTUE OF LESS CLOUDS...WITH WIDESPREAD 60S EXPECTED
DAYBREAK SUNDAY. MAXIMUMS TEMPS SHOULD BE WARMER ON SUNDAY FOR
SIMILAR REASONS OF LESS CLOUD COVER. RETURN FLOW BEGINS LATE
SUNDAY EVENING WITH A WEAK WIND SHIFT TO NORTH OVER OUR NC
ZONES INTO DAYBREAK MONDAY AS THE CANADIAN HIGH DIPS INTO THE
MID-ATLANTIC REGION.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 3 PM FRIDAY...MID LEVEL RIDGING WILL BE THE PREVAILING
FEATURE FOR THE FIRST HALF OF THE FORECAST PERIOD. THERE WILL BE
SUFFICIENT MOISTURE IN THE COLUMN...PRECIPITABLE WATER VALUES OF
1.80 INCHES... TO MAINTAIN SLIGHT CHANCE POPS MONDAY BEFORE A
SURGE OF DRIER AIR MOVES IN FROM THE NORTHEAST. THIS WILL KEEP
POPS OUT OF THE PICTURE FOR TUESDAY AND WEDNESDAY. A SIGNIFICANT
MID LEVEL TROUGH WILL BRING ANOTHER RELATIVELY STRONG COLD FRONT
ACROSS THE AREA FRIDAY. THE SOUTHERLY FLOW AHEAD OF THIS SYSTEM
WILL ALLOW SLIGHT CHANCE POPS TO CREEP BACK INTO THE FORECAST
THURSDAY WITH THE BETTER FORCING WARRANTING CHANCE VALUES FRIDAY.
TEMPERATURE FORECAST LOOKS STABLE WITH VALUES JUST A DEGREE OR TWO
ABOVE CLIMATOLOGY THROUGH THE PERIOD.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 18Z...TERMINALS ARE VFR THIS AFTERNOON AND VFR IS EXPECTED
THIS TAF VALID PERIOD...EXCEPT FROM MIDNIGHT UNTIL JUST AFTER
SUNRISE. AN UPPER IMPULSE WILL PASS LATE THIS AFTERNOON. HIGH
RESOLUTION MODELS CONTINUE TO INDICATE SHOWERS AND POSSIBLY AN
ISOLATED THUNDERSTORM MOVING SOUTHWEST TOWARDS MAINLY KILM. WILL
INDICATE VCSH LATER THIS AFTERNOON ONLY AT KILM WHERE A RESULTANT
BOUNDARY WILL INTERACT WITH THE IMPULSE AT MAX HEATING. SINCE ANY
THUNDERSTORM IS EXPECTED TO BE ISOLATED THERE IS LOW CONFIDENCE OF
VCTS. VCSH WILL END 01-02Z.
MODELS SOUNDINGS ARE INDICATING SUFFICIENT LOW-LEVEL MOISTURE TO
PRODUCE MVFR/IFR CONDITIONS AFTER 06Z. MVFR WILL POSSIBLY OCCUR AT
KILM/KCRE/KMYR ALTHOUGH BEST CONFIDENCE OF OCCURRENCE WILL BE AT
KMYR. THE BEST CHANCE OF IFR WILL BE AT KFLO...AND TO A LESSER
EXTENT KLBT. VFR EXPECTED AFTER 14Z AT ALL TERMINALS WITH NE-ENE
WINDS.
EXTENDED OUTLOOK...MORNING FOG/STRATUS IS POSSIBLE THROUGH THE
EXTENDED PERIOD. SLIGHT CHANCE OF SHOWERS SUNDAY NIGHT THROUGH
TUESDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 615 PM FRIDAY...I HAVE UPDATED THE MARINE FORECAST TO INCREASE
THE POTENTIAL OF THUNDERSTORMS THIS EVENING...MAINLY FROM AROUND
CAPE FEAR NORTH TO SURF CITY. LATEST NEAR-TERM HIGH RESOLUTION
MODELS SHOW THE THUNDERSTORM ACTIVITY APPROACHING SURF CITY MAY MAKE
IT DOWN TO SOUTHPORT OVER THE NEXT 2-3 HOURS. AFTER REVIEWING THE
LATEST SYNOPTIC MODELS FOR THE OVERNIGHT PERIOD I HAVE INCREASED
WIND SPEED FORECASTS BY A FEW KNOTS AFTER MIDNIGHT AND HAVE BACKED
WIND DIRECTIONS BY ABOUT 30 DEGREES...MORE NORTHEAST THAN EAST.
PREVIOUS DISCUSSION FROM 300 PM FOLLOWS...
HIGH PRESSURE BUILDING SOUTH FROM THE MID-ATLANTIC WILL CONTINUE TO
RIDGE ACROSS THE WATERS TONIGHT...PERSISTING THE NE WINDS PRESENTLY
OBSERVED AT THE LOCAL BUOYS. WHILE WINDS HAVE BEEN AROUND 10 KTS
MUCH OF THE DAY...A MDT NE SURGE IS STILL PROGGED TONIGHT...DRIVING
WINDS UP TO AROUND 15 KTS LATE IN THE PERIOD. THESE WINDS WILL FORCE
RISING WAVE HEIGHTS...FROM 1-3 FT...UP TO 3-4 FT LATE TONIGHT WITH A
5 SEC NE WIND CHOP REMAINING DOMINANT WITHIN THE WAVE SPECTRUM.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...MODERATE NE WINDS CAN BE EXPECTED ON THE
WATERS SATURDAY AS CANADIAN HIGH PRESSURE DROPS SE TOWARD THE
COASTAL WATERS. THIS MAY BRING SEAS TO 4 FEET OVER THE OUTER
WATERS AND ALSO NORTH OF CAPE FEAR...BUT NO ADVISORIES OR TSTMS
ARE EXPECTED. LIGHT SHOWERS HOWEVER MAY DOT THE WATERS SATURDAY
AND MAINLY NORTH OF CAPE FEAR. WINDS WILL EASE AND BECOME LIGHT
SATURDAY NIGHT AND SUNDAY AS THE HIGH MOVES NEARLY OVERHEAD OF
THE WATERS. AS THE HIGH MOVES OFFSHORE SUNDAY EVENING...EXPECT
WINDS TO BECOME S AND SW. HIGHEST WINDS AND SEAS ARE ANTICIPATED
SATURDAY WITH OVERALL IMPROVING CONDITIONS LATE SATURDAY AND
SUNDAY. LATE SUNDAY NIGHT INTO EARLY MONDAY HIGH PRESSURE DROPPING
FROM THE NORTH WILL BRING A WEAK COLD FRONT TO THE NC WATERS. THIS
SHOULD BRING A WIND-SHIFT NORTH OF CAPE FEAR BY DAYBREAK MONDAY.
LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 3 PM FRIDAY...EASTERLY WINDS INITIALLY WILL BACK TO
NORTHEASTERLY LATE MONDAY AND VACILLATE BETWEEN EAST TO NORTHEAST
THROUGH WEDNESDAY. THERE MAY BE A LATE SHIFT VERY LATE IN THE PERIOD
WEDNESDAY TO SOUTHEAST AS THE PATTERN SHIFTS A BIT BUT THIS WILL
NEED TO BE FINE TUNED IN SUBSEQUENT FORECASTS. WIND SPEEDS WILL
REMAIN EITHER SIDE OF TEN KNOTS THROUGHOUT THE PERIOD. WAVEWATCH
SEAS CONTINUE THE SEEMINGLY SUMMER LONG TREND OF BENIGN SEAS WITH
2-3 FEET PRIMARILY COMPRISED OF SHORTER PERIOD WIND WAVES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...8
NEAR TERM...JDW/TRA
SHORT TERM...MJC
LONG TERM...SHK
AVIATION...MRR/JDW
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
735 AM EDT FRI SEP 6 2013
.SYNOPSIS...
HIGH PRESSURE IS EXPECTED ACROSS THE AREA INTO THE WEEKEND. ANOTHER
COLD FRONT WILL DROP ACROSS THE REGION AND DISSIPATE EARLY NEXT
WEEK...FOLLOWED BY HIGH PRESSURE INTO MID-WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...VIA LATEST OBS...AND NAM AND HRRR SFC WIND
FIELDS...N TO NE WINDS HAVE ENGULFED THE ILM CWA AND ADJACENT
COASTAL WATERS. NOTICEABLY LOWER DEWPOINTS...WIDESPREAD 60S...
WILL CONTINUE TO ADVECT ACROSS THE FA AS THE POST FRONTAL 1025+
MB SFC HIGH RIDGES ACROSS THE FA FROM THE NORTH. THE TIGHTENED SFC
PG SHOULD KEEP N-NE WINDS AT 5 TO 15 MPH...THE HIER SIDE OF THIS
RANGE TO OCCUR ALONG THE IMMEDIATE COAST. MAX TEMPS WILL ALSO BE
NOTICEABLY DIFFERENT COMPARED TO PREVIOUS WEEKDAYS...WITH
WIDESPREAD 80S AND ONLY A FEW 90 DEGREE READINGS ACROSS THE FAR SW
PORTION OF THE FA. THERE IS HOWEVER...A WEAK S/W TROF IN THE MID-
LEVELS ROTATING THRU THE LONGWAVE UPPER TROF...WITH ITS CURRENT
AXIS LYING JUST OFF THE EAST COAST OF THE U.S. THIS S/W TROF WILL
HAVE AVAILABLE MOISTURE TO WORK WITH AS IT PUSHES SOUTHWARD TO AND
ACROSS THE FA LATE THIS AFTERNOON AND TONIGHT. AT THIS
POINT...MODEL TIME HEIGHTS INDICATE POSSIBLE SHALLOW CU/STRATOCU
DECK TO AFFECT THE FA WITH LITTLE VERTICAL EXTENT. IN FACT THE
MID AND UPPER LEVELS REMAIN QUITE DRY. NEVERTHELESS...COULD STILL
SQUEEZE OUT AN ISOLATED SHOWER BUT FOR NOW WILL JUST HIGHLIGHT THE
POSSIBLE CLOUDINESS. MIN TEMP FORECAST COULD BECOME TRICKY DUE TO
THE STRATOCU DECK. FOR NOW...WILL STAY ON THE SLIGHTLY MILDER SIDE
OF MODEL MOS GUIDANCE WITH WIDESPREAD MID 60S...UPPER 60S AT THE
COAST...COVERING IT.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...SATURDAY BRINGS NW FLOW ALOFT AS TROUGH AXIS
MOVES OFF THE COAST. MEANWHILE SURFACE GRADIENT WILL BE VERY LIGHT
AS HIGH PRESSURE WEAKENS ACROSS THE SOUTHEAST WHILE MAINTAINING A
PRESENCE OFF THE NEW ENGLAND COAST AS WELL AS GULF COAST. EXPECT
PARTLY SUNNY SKY AND SEASONABLE TEMPERATURES. FLOW ALOFT TURNS TO
NORTHERLY ON SUNDAY WHILE SURFACE FLOW REMAINS SIMILARLY WEAK. GOOD
INSOLATION WILL ADD A FEW DEGREES TO HIGHS AND THERE MAY EVEN BE A
BIT LESS SKY COVER DUE TO THE WEAK HEIGHT RISES ASSOC WITH THE
EXITING TROUGHINESS. A COLD FRONT ENTERS THE AREA LATE SUNDAY NIGHT
BUT WILL BE TOO DEPRIVED OF MOISTURE TO BRING ANY MENTIONABLE RAIN
CHANCES.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM FRIDAY...BACKDOOR COLD FRONT SLIPS THROUGH FIRST THING
MONDAY WITH INSUFFICIENT MOISTURE TO BRING ANY REAL CHANCE FOR RAIN.
IN THE UPPER LEVELS THE RIDGING THAT HAD BEEN CONFINED TO THE
NATIONS MIDSECTION DURING THE SHORT TERM WILL NOW BE VERY BROAD AND
WEAK AND COVER REAL ESTATE FROM NM/CO TO THE WEST ATLANTIC. AS SUCH
THERE WILL BE LITTLE COOL ADVECTION IN THE LOW LEVELS AND SEASONABLE
TEMPS ARE EXPECTED FOR MOST OF THE PERIOD. THE HIGH INITIALLY BEHIND
THE FRONT WILL BE CENTERED OVER NEW ENGLAND ON MONDAY. IT WILL
WEAKEN AND PROGRESS EASTWARD THROUGH THE PERIOD BUT EXTEND AN AXIS
INTO THE SOUTHEAST THE ENTIRE TIME PRECLUDING MUCH MOISTURE FLUX
INTO THE CAROLINAS.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 12Z...TERMINALS ARE VFR THIS MORNING AND VFR IS EXPECTED
THROUGH MIDNIGHT. SCATTERED 200 FOOT STRATUS AT KCRE IS EXPECTED
TO MIX OUT QUICKLY OVER THE NEXT HOUR OR TWO. AN UPPER IMPULSE
WILL PASS LATER TODAY WITH SHOWERS AND POSSIBLY A THUNDERSTORM
MOVING SOUTH TOWARDS KILM. WILL INDICATE VCSH LATER THIS AFTERNOON
ONLY AT KILM WHERE A RESULTANT BOUNDARY WILL INTERACT WITH THE
IMPULSE AT MAX HEATING. SINCE ANY THUNDERSTORM IS EXPECTED TO BE
ISOLATED THERE IS LOW CONFIDENCE OF VCTS AT KILM. ACTIVITY WILL
MOVE OFFSHORE 01-02Z.
MODELS SOUNDINGS ARE INDICATING SUFFICIENT LOW-LEVEL MOISTURE TO
PRODUCE MVFR/IFR CONDITIONS AFTER 06Z. THE BEST CHANCE OF MVFR WILL
BE AT THE KILM/KCRE/KMYR WITH THE BEST CHANCE OF IFR AT KFLO AND TO
A LESSER EXTENT KLBT.
EXTENDED OUTLOOK...MORNING FOG/STRATUS IS POSSIBLE THROUGH THE
EXTENDED PERIOD. SLIGHT CHANCE OF SHOWERS SUNDAY NIGHT AND MONDAY.
OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...THE SFC COLD FRONT HAS EXITED SOUTH OF THE
ILM WATERS BY DAYBREAK FRI. THE POST FRONTAL SFC PRESSURE PATTERN
AND TIGHTENED SFC PG WILL YIELD A NE TO ENE WIND AT 10 TO 15 KT
WITH FEW GUSTS OVER 20 KT TODAY INTO TONIGHT. COULD APPROACH SCEC
CONDITIONS TONIGHT AS A NE SURGE ACCOMPANYING THE MID-LEVEL S/W
TROF...COULD AFFECT THE ILM WATERS OVERNIGHT. WILL NEED TO CLOSELY
MONITOR THIS. SIGNIFICANT SEAS DOMINATED BY AN EASTERLY GROUND
SWELL AT 9 SECOND PERIODS FOR THE PAST FEW DAYS...WILL BECOME
DOMINATED BY WIND DRIVEN WAVES AT 3 TO 6 SECOND PERIODS. COULD SEE
2 TO 4 FT SIG SEAS DEVELOP BY OR DURING THE OVERNIGHT PERIOD.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...WEAKENING HIGH PRESSURE ACROSS THE SOUTHEASTERN
U.S. WHILE MAIN RIDGE MOVES OFF THE NEW ENGLAND COAST. THIS MEANS
AN EASTERLY WIND ACROSS THE FORECAST ZONES AND A GENERAL 2 TO 4 FT
SEAS FCST NORTH AND 2 TO 3 SOUTH. A PREFRONTAL TROUGH DEVELOPS
OVER LAND ON SUNDAY TURING WINDS TO SWRLY WHILE ALSO WEAKENING THE
GRADIENT ENOUGH FOR ABOUT A 5 KT DECREASE IN WIND AND PERHAPS 1 FT
DECREASE IN SEAS. THE COLD FRONT MAY BE ENCROACHING UPON
NORTHERNMOST ZONE BY THE END OF THE PERIOD.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM FRIDAY...BACKDOOR COLD FRONT PUSHES THROUGH EARLY MONDAY.
HIGH PRESSURE DOES NOT PUSH THE BOUNDARY VERY FAR TO THE SOUTH SO NO
REAL NORTHERLY COMPONENT POST FROPA JUST A VEER TO THE NE AND THEN
EAST. ON TUESDAY HIGH PRESSURE WEAKENS BUT MAINTAINS IT PRESENCE
INTO THE SOUTHEASTERN U.S. FROM ITS MAIN CENTER MOVING OFF THE NEW
ENGLAND COAST. WIND REMAINS ONSHORE/EASTERLY AND VERY LIGHT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MBB/MRR
NEAR TERM...DCH
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...MRR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
704 AM EDT FRI SEP 6 2013
.SYNOPSIS...
AN APPROACHING COLD FRONT WILL CROSS THE AREA EARLY FRIDAY FOLLOWED
BY CANADIAN HIGH PRESSURE FRIDAY INTO THE WEEKEND. ANOTHER COLD FRONT
WILL DROP ACROSS THE REGION AND DISSIPATE EARLY NEXT WEEK FOLLOWED BY
HIGH PRESSURE INTO MID-WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...VIA LATEST OBS...AND NAM AND HRRR SFC WIND
FIELDS...N TO NE WINDS HAVE ENGULFED THE ILM CWA AND ADJACENT
COASTAL WATERS. NOTICEABLY LOWER DEWPOINTS...WIDESPREAD 60S...
WILL CONTINUE TO ADVECT ACROSS THE FA AS THE POST FRONTAL 1025+
MB SFC HIGH RIDGES ACROSS THE FA FROM THE NORTH. THE TIGHTENED SFC
PG SHOULD KEEP N-NE WINDS AT 5 TO 15 MPH...THE HIER SIDE OF THIS
RANGE TO OCCUR ALONG THE IMMEDIATE COAST. MAX TEMPS WILL ALSO BE
NOTICEABLY DIFFERENT COMPARED TO PREVIOUS WEEKDAYS...WITH
WIDESPREAD 80S AND ONLY A FEW 90 DEGREE READINGS ACROSS THE FAR SW
PORTION OF THE FA. THERE IS HOWEVER...A WEAK S/W TROF IN THE MID-
LEVELS ROTATING THRU THE LONGWAVE UPPER TROF...WITH ITS CURRENT
AXIS LYING JUST OFF THE EAST COAST OF THE U.S. THIS S/W TROF WILL
HAVE AVAILABLE MOISTURE TO WORK WITH AS IT PUSHES SOUTHWARD TO AND
ACROSS THE FA LATE THIS AFTERNOON AND TONIGHT. AT THIS
POINT...MODEL TIME HEIGHTS INDICATE POSSIBLE SHALLOW CU/STRATOCU
DECK TO AFFECT THE FA WITH LITTLE VERTICAL EXTENT. IN FACT THE
MID AND UPPER LEVELS REMAIN QUITE DRY. NEVERTHELESS...COULD STILL
SQUEEZE OUT AN ISOLATED SHOWER BUT FOR NOW WILL JUST HIGHLIGHT THE
POSSIBLE CLOUDINESS. MIN TEMP FORECAST COULD BECOME TRICKY DUE TO
THE STRATOCU DECK. FOR NOW...WILL STAY ON THE SLIGHTLY MILDER SIDE
OF MODEL MOS GUIDANCE WITH WIDESPREAD MID 60S...UPPER 60S AT THE
COAST...COVERING IT.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...SATURDAY BRINGS NW FLOW ALOFT AS TROUGH AXIS
MOVES OFF THE COAST. MEANWHILE SURFACE GRADIENT WILL BE VERY LIGHT
AS HIGH PRESSURE WEAKENS ACROSS THE SOUTHEAST WHILE MAINTAINING A
PRESENCE OFF THE NEW ENGLAND COAST AS WELL AS GULF COAST. EXPECT
PARTLY SUNNY SKY AND SEASONABLE TEMPERATURES. FLOW ALOFT TURNS TO
NORTHERLY ON SUNDAY WHILE SURFACE FLOW REMAINS SIMILARLY WEAK. GOOD
INSOLATION WILL ADD A FEW DEGREES TO HIGHS AND THERE MAY EVEN BE A
BIT LESS SKY COVER DUE TO THE WEAK HEIGHT RISES ASSOC WITH THE
EXITING TROUGHINESS. A COLD FRONT ENTERS THE AREA LATE SUNDAY NIGHT
BUT WILL BE TOO DEPRIVED OF MOISTURE TO BRING ANY MENTIONABLE RAIN
CHANCES.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM FRIDAY...BACKDOOR COLD FRONT SLIPS THROUGH FIRST THING
MONDAY WITH INSUFFICIENT MOISTURE TO BRING ANY REAL CHANCE FOR RAIN.
IN THE UPPER LEVELS THE RIDGING THAT HAD BEEN CONFINED TO THE
NATIONS MIDSECTION DURING THE SHORT TERM WILL NOW BE VERY BROAD AND
WEAK AND COVER REAL ESTATE FROM NM/CO TO THE WEST ATLANTIC. AS SUCH
THERE WILL BE LITTLE COOL ADVECTION IN THE LOW LEVELS AND SEASONABLE
TEMPS ARE EXPECTED FOR MOST OF THE PERIOD. THE HIGH INITIALLY BEHIND
THE FRONT WILL BE CENTERED OVER NEW ENGLAND ON MONDAY. IT WILL
WEAKEN AND PROGRESS EASTWARD THROUGH THE PERIOD BUT EXTEND AN AXIS
INTO THE SOUTHEAST THE ENTIRE TIME PRECLUDING MUCH MOISTURE FLUX
INTO THE CAROLINAS.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 06Z...IT IS A TRICKY FOG FORECAST OVERNIGHT AS A COLD FRONT IS
EXPECTED TO MOVE THROUGH THE FORECAST AREA BEFORE 12Z...USHERING IN
SLIGHTLY COOLER AND DRIER AIR. MVFR FOG REMAINS POSSIBLE ACROSS
KLBT/KFLO TERMINALS GIVEN THE DELAY OF THE NNW-NE WINDS AND THE
LOWER SFC DEWPOINTS ACCOMPANYING THEM FROM UPSTREAM. THE BEST FOG
POTENTIAL WILL BE ALONG THE COAST...ESPECIALLY AT KCRE. EXPECT
MVFR/IFR VSBYS AT KCRE AND MVFR VSBYS AT KILM/KMYR UNTIL THE WEAK
NNW-NE SURGE ARRIVES TOWARD DAYBREAK FRI. THE DRIER AIR AND
LOW-LEVEL MIXING WILL HELP VSBYS RAPIDLY IMPROVE...WITH VFR
PREVAILING FOR THE REST OF THE PERIOD. MODEL MOS GUIDANCE HAS
INDICATED THAT KCRE/KMYR MAY HAVE A PROLONGED REDUCED VSBY FROM HAZE
DURING THE DAYTIME MORNING HRS...UNTIL THE POST FRONTAL LOW LEVEL
MIXING FINALLY ARRIVES. THERE IS A SLIGHT CHANCE FOR ISOLATED
CONVECTION...BUT COVERAGE REMAINS VERY LIMITED AND THUS DID NOT
WARRANT MENTIONING IN THE TAFS.
EXTENDED OUTLOOK...MORNING FOG/STRATUS IS POSSIBLE THROUGH THE
EXTENDED PERIOD. SLIGHT CHANCE OF SHOWERS SUNDAY NIGHT AND MONDAY.
OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...THE SFC COLD FRONT HAS EXITED SOUTH OF THE
ILM WATERS BY DAYBREAK FRI. THE POST FRONTAL SFC PRESSURE PATTERN
AND TIGHTENED SFC PG WILL YIELD A NE TO ENE WIND AT 10 TO 15 KT
WITH FEW GUSTS OVER 20 KT TODAY INTO TONIGHT. COULD APPROACH SCEC
CONDITIONS TONIGHT AS A NE SURGE ACCOMPANYING THE MID-LEVEL S/W
TROF...COULD AFFECT THE ILM WATERS OVERNIGHT. WILL NEED TO CLOSELY
MONITOR THIS. SIGNIFICANT SEAS DOMINATED BY AN EASTERLY GROUND
SWELL AT 9 SECOND PERIODS FOR THE PAST FEW DAYS...WILL BECOME
DOMINATED BY WIND DRIVEN WAVES AT 3 TO 6 SECOND PERIODS. COULD SEE
2 TO 4 FT SIG SEAS DEVELOP BY OR DURING THE OVERNIGHT PERIOD.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...WEAKENING HIGH PRESSURE ACROSS THE SOUTHEASTERN
U.S. WHILE MAIN RIDGE MOVES OFF THE NEW ENGLAND COAST. THIS MEANS
AN EASTERLY WIND ACROSS THE FORECAST ZONES AND A GENERAL 2 TO 4 FT
SEAS FCST NORTH AND 2 TO 3 SOUTH. A PREFRONTAL TROUGH DEVELOPS
OVER LAND ON SUNDAY TURING WINDS TO SWRLY WHILE ALSO WEAKENING THE
GRADIENT ENOUGH FOR ABOUT A 5 KT DECREASE IN WIND AND PERHAPS 1 FT
DECREASE IN SEAS. THE COLD FRONT MAY BE ENCROACHING UPON
NORTHERNMOST ZONE BY THE END OF THE PERIOD.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM FRIDAY...BACKDOOR COLD FRONT PUSHES THROUGH EARLY MONDAY.
HIGH PRESSURE DOES NOT PUSH THE BOUNDARY VERY FAR TO THE SOUTH SO NO
REAL NORTHERLY COMPONENT POST FROPA JUST A VEER TO THE NE AND THEN
EAST. ON TUESDAY HIGH PRESSURE WEAKENS BUT MAINTAINS IT PRESENCE
INTO THE SOUTHEASTERN U.S. FROM ITS MAIN CENTER MOVING OFF THE NEW
ENGLAND COAST. WIND REMAINS ONSHORE/EASTERLY AND VERY LIGHT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MBB
NEAR TERM...DCH
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...DCH/BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
404 AM EDT FRI SEP 6 2013
.SYNOPSIS...
AN APPROACHING COLD FRONT WILL CROSS THE AREA EARLY FRIDAY FOLLOWED
BY CANADIAN HIGH PRESSURE FRIDAY INTO THE WEEKEND. ANOTHER COLD FRONT
WILL DROP ACROSS THE REGION AND DISSIPATE EARLY NEXT WEEK FOLLOWED BY
HIGH PRESSURE INTO MID-WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 330 AM FRIDAY...SFC COLD FRONT IS CURRENTLY PUSHING
SOUTHWARD ACROSS THE ILM CWA AT THE MOMENT...AND SHOULD CLEAR THE
ILM CWA AROUND DAYBREAK FRI. THIS VIA LATEST NAM AND HRRR SFC WIND
FIELDS. NOTICEABLY LOWER DEWPOINTS WILL ALSO BE ADVECTING ACROSS
THE FA AS THE POST FRONTAL 1025+ MB SFC HIGH RIDGES ACROSS THE FA
FROM THE NORTH. THE TIGHTENED SFC PG SHOULD KEEP N-NE WINDS AT 5 TO
15 MPH...THE HIER SIDE OF THIS RANGE TO OCCUR ALONG THE COAST. MAX
TEMPS WILL ALSO BE NOTICEABLY DIFFERENT COMPARED TO PREVIOUS
WEEKDAYS...WITH WIDESPREAD 80S AND ONLY A FEW 90 DEGREE READINGS
ACROSS THE FAR SW PORTION OF THE FA. THERE IS HOWEVER...A WEAK S/W
TROF IN THE MID-LEVELS ROTATING THRU THE LONGWAVE UPPER TROF WITH
ITS CURRENT AXIS LYING JUST OFF THE EAST COAST OF THE U.S. THIS
S/W TROF WILL HAVE AVAILABLE MOISTURE TO WORK WITH AS IT PUSHES
SOUTHWARD TO AND ACROSS THE FA LATE THIS AFTERNOON AND TONIGHT. AT
THIS POINT...MODEL TIME HEIGHTS INDICATE POSSIBLE SHALLOW STRATOCU
DECK TO AFFECT THE FA WITH LITTLE VERTICAL EXTENT. IN FACT THE MID
AND UPPER LEVELS REMAIN QUITE DRY. NEVERTHELESS...COULD STILL
SQUEEZE OUT AN ISOLATED SHOWER BUT FOR NOW WILL JUST HIGHLIGHT THE
POSSIBLE CLOUDINESS. WIDESPREAD 80S FOR MAX TEMPS...WITH A FEW 90
DEGREE READING ACROSS THE FAR SW PORTIONS OF THE FA. MIN TEMP
FORECAST COULD BECOME TRICKY DUE TO THE STRATOCU DECK. FOR
NOW...WILL STAY ON THE SLIGHTLY MILDER SIDE OF MODEL MOS GUIDANCE
WITH WIDESPREAD 60S COVERING IT.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...SATURDAY BRINGS NW FLOW ALOFT AS TROUGH AXIS
MOVES OFF THE COAST. MEANWHILE SURFACE GRADIENT WILL BE VERY LIGHT
AS HIGH PRESSURE WEAKENS ACROSS THE SOUTHEAST WHILE MAINTAINING A
PRESENCE OFF THE NEW ENGLAND COAST AS WELL AS GULF COAST. EXPECT
PARTLY SUNNY SKY AND SEASONABLE TEMPERATURES. FLOW ALOFT TURNS TO
NORTHERLY ON SUNDAY WHILE SURFACE FLOW REMAINS SIMILARLY WEAK. GOOD
INSOLATION WILL ADD A FEW DEGREES TO HIGHS AND THERE MAY EVEN BE A
BIT LESS SKY COVER DUE TO THE WEAK HEIGHT RISES ASSOC WITH THE
EXITING TROUGHINESS. A COLD FRONT ENTERS THE AREA LATE SUNDAY NIGHT
BUT WILL BE TOO DEPRIVED OF MOISTURE TO BRING ANY MENTIONABLE RAIN
CHANCES.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM FRIDAY...BACKDOOR COLD FRONT SLIPS THROUGH FIRST THING
MONDAY WITH INSUFFICIENT MOISTURE TO BRING ANY REAL CHANCE FOR RAIN.
IN THE UPPER LEVELS THE RIDGING THAT HAD BEEN CONFINED TO THE
NATIONS MIDSECTION DURING THE SHORT TERM WILL NOW BE VERY BROAD AND
WEAK AND COVER REAL ESTATE FROM NM/CO TO THE WEST ATLANTIC. AS SUCH
THERE WILL BE LITTLE COOL ADVECTION IN THE LOW LEVELS AND SEASONABLE
TEMPS ARE EXPECTED FOR MOST OF THE PERIOD. THE HIGH INITIALLY BEHIND
THE FRONT WILL BE CENTERED OVER NEW ENGLAND ON MONDAY. IT WILL
WEAKEN AND PROGRESS EASTWARD THROUGH THE PERIOD BUT EXTEND AN AXIS
INTO THE SOUTHEAST THE ENTIRE TIME PRECLUDING MUCH MOISTURE FLUX
INTO THE CAROLINAS.
&&
.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
AS OF 06Z...IT IS A TRICKY FOG FORECAST OVERNIGHT AS A COLD FRONT IS
EXPECTED TO MOVE THROUGH THE FORECAST AREA BEFORE 12Z...USHERING IN
SLIGHTLY COOLER AND DRIER AIR. MVFR FOG REMAINS POSSIBLE ACROSS
KLBT/KFLO TERMINALS GIVEN THE DELAY OF THE NNW-NE WINDS AND THE
LOWER SFC DEWPOINTS ACCOMPANYING THEM FROM UPSTREAM. THE BEST FOG
POTENTIAL WILL BE ALONG THE COAST...ESPECIALLY AT KCRE. EXPECT
MVFR/IFR VSBYS AT KCRE AND MVFR VSBYS AT KILM/KMYR UNTIL THE WEAK
NNW-NE SURGE ARRIVES TOWARD DAYBREAK FRI. THE DRIER AIR AND
LOW-LEVEL MIXING WILL HELP VSBYS RAPIDLY IMPROVE...WITH VFR
PREVAILING FOR THE REST OF THE PERIOD. MODEL MOS GUIDANCE HAS
INDICATED THAT KCRE/KMYR MAY HAVE A PROLONGED REDUCED VSBY FROM HAZE
DURING THE DAYTIME MORNING HRS...UNTIL THE POST FRONTAL LOW LEVEL
MIXING FINALLY ARRIVES. THERE IS A SLIGHT CHANCE FOR ISOLATED
CONVECTION...BUT COVERAGE REMAINS VERY LIMITED AND THUS DID NOT
WARRANT MENTIONING IN THE TAFS.
EXTENDED OUTLOOK...MORNING FOG/STRATUS IS POSSIBLE THROUGH THE
EXTENDED PERIOD. SLIGHT CHANCE OF SHOWERS SUNDAY NIGHT AND MONDAY.
OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 345 AM FRIDAY...THE SFC COLD FRONT WILL BE EXITTING SOUTH OF
THE ILM WATERS BY DAYBREAK FRI. THE POST FRONTAL SFC PRESSURE
PATTERN AND TIGHTENED SFC PG WILL YIELD A NE TO ENE WIND AT 10 TO
15 KT WITH GUSTS OVER 20 KT TODAY INTO TONIGHT. COULD APPROACH
SCEC CONDITIONS TONIGHT AS A NE SURGE ACCOMPANYING THE MID-LEVEL
S/W TROF...COULD AFFECT THE ILM WATERS OVERNIGHT. WILL NEED TO
CLOSELY MONITOR THIS. SIGNIFICANT SEAS DOMINATED BY AN EASTERLY
GROUND SWELL AT 9 SECOND PERIODS FOR THE PAST FEW DAYS...WILL
BECOME DOMINATED BY WIND DRIVEN WAVES AT 3 TO 6 SECOND PERIODS.
COULD SEE 2 TO 4 FT SIG SEAS DEVELOP DURING THE OVERNIGHT PERIOD.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...WEAKENING HIGH PRESSURE ACROSS THE SOUTHEASTERN
U.S. WHILE MAIN RIDGE MOVES OFF THE NEW ENGLAND COAST. THIS MEANS
AN EASTERLY WIND ACROSS THE FORECAST ZONES AND A GENERAL 2 TO 4 FT
SEAS FCST NORTH AND 2 TO 3 SOUTH. A PREFRONTAL TROUGH DEVELOPS
OVER LAND ON SUNDAY TURING WINDS TO SWRLY WHILE ALSO WEAKENING THE
GRADIENT ENOUGH FOR ABOUT A 5 KT DECREASE IN WIND AND PERHAPS 1 FT
DECREASE IN SEAS. THE COLD FRONT MAY BE ENCROACHING UPON
NORTHERNMOST ZONE BY THE END OF THE PERIOD.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM FRIDAY...BACKDOOR COLD FRONT PUSHES THROUGH EARLY MONDAY.
HIGH PRESSURE DOES NOT PUSH THE BOUNDARY VERY FAR TO THE SOUTH SO NO
REAL NORTHERLY COMPONENT POST FROPA JUST A VEER TO THE NE AND THEN
EAST. ON TUESDAY HIGH PRESSURE WEAKENS BUT MAINTAINS IT PRESENCE
INTO THE SOUTHEASTERN U.S. FROM ITS MAIN CENTER MOVING OFF THE NEW
ENGLAND COAST. WIND REMAINS ONSHORE/EASTERLY AND VERY LIGHT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MBB
NEAR TERM...DCH
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...DCH/BJR
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1234 PM CDT FRI SEP 6 2013
.UPDATE...
ISSUED AT 1234 PM CDT FRI SEP 6 2013
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE TO TRACK
ACROSS CENTRAL NORTH DAKOTA. 15 UTC HRRR SHOWS THE AREA OF SHOWERS
AROUND BISMARCK HOLDING TOGETHER THROUGH THE JAMESTOWN AREA.
ALTHOUGH LITTLE MORE THAN A FEW SPRINKLES CAN BE EXPECTED MOST
AREAS...THE INCREASED CLOUD COVER WILL LIKELY KEEP TEMPERATURES
FROM REACHING FORECAST HIGHS...THEREFORE WE LOWERED MAXIMUM
TEMPERATURES 2-5 DEGREES MOST AREAS. SURFACE DEW POINTS REMAIN IN
THE MID TO UPPER 60S WHICH IS A LITTLE HIGHER THAN FORECAST. THUS
EVEN THOUGH WE MAY NOT QUITE REACH OUR FORECAST HIGHS...WITH THE
ADDED MOISTURE...IT WILL REMAIN QUITE UNCOMFORTABLE THIS
AFTERNOON. SO WILL CONTINUE THE HEAT ADVISORY FOR NOW.
UPDATE ISSUED AT 1013 AM CDT FRI SEP 6 2013
IMPULSE MOVING THROUGH UPPER LEVEL RIDGE IS PRODUCING SCATTERED
THUNDERSTORMS OVER WESTERN AND CENTRAL NORTH DAKOTA THIS MORNING.
ONCE CELL OVER BOWMAN COUNTY PRODUCED QUARTER TO GOLF BALL SIZED
HAIL. EXPECT SCATTERED CONVECTION TO HAVE A HARD TIME MAINTAINING
ITSELF AS IT MOVES INTO CENTRAL NORTH DAKOTA...SOUTH OF THE
INTERSTATE. FARTHER NORTH WHERE CAP IS NOT AS STRONG...WILL
MAINTAIN A CHANCE OF THUNDERSTORMS THROUGH THE AFTERNOON. UPDATE
THIS MORNING WAS MAINLY FOR CLOUDS AND POPS BASED ON CURRENT RADAR
AND SATELLITE DATA. CURRENT CLOUD COVER MAY INHIBIT HEATING OVER
CENTRAL NORTH DAKOTA. WILL TAKE A CLOSER LOOK AT TEMPERATURES LATE
MORNING. NO CHANGES AT THIS TIME TO CURRENT HEAT ADVISORY.
UPDATE ISSUED AT 643 AM CDT FRI SEP 6 2013
SCATTERED THUNDERSTORMS CONTINUE TO ROTATE INTO WESTERN NORTH
DAKOTA AHEAD OF A SHORTWAVE. THE CURRENT FORECAST HAS THIS
SCENARIO HANDLED QUITE WELL...IN SPITE OF POOR MODEL GUIDANCE.
OTHERWISE...ONLY NEEDED TO ADJUST THE HOURLY SENSIBLE WEATHER
GRIDS BASED ON CURRENT OBS/TRENDS. THE UPDATED GRIDDED AND TEXT
PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 535 AM CDT FRI SEP 6 2013
MID LEVEL ENERGY ROTATING AROUND THE RIDGE AXIS GENERATING AN
EXTENSIVE AREA OF SHOWERS/SCATTERED THUNDERSTORMS OVER EASTERN
MONTANA...MOVING EAST INTO WESTERN NORTH DAKOTA. MODELS EARLIER
FAILED TO CAPTURE THE TRUE EXTENT OF THE WAVE...WHICH IS NOW
BECOMING MORE EVIDENT AS PRECIPITATION MOVES INTO WESTERN NORTH
DAKOTA. UPDATED FORECAST TO INCREASE POPS THIS MORNING.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 409 AM CDT FRI SEP 6 2013
FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE HEAT AND
HUMIDITY THIS AFTERNOON...ALONG WITH CHANCES FOR THUNDERSTORMS
THROUGH THE PERIOD.
CURRENTLY...UPPER LEVEL HIGH PRESSURE CENTERED OVER EASTERN
COLORADO WITH THE RIDGE AXIS EXTENDING NORTH THROUGH THE NORTHERN
HIGH PLAINS INTO SOUTHERN ALBERTA. DEEP UPPER LEVEL LOW CENTERED
OVER OREGON EARLY THIS MORNING. WATER VAPOR AND NEAR TERM MODEL
GUIDANCE DEPICT AN EMBEDDED S/WV ROTATING NORTHEAST AROUND/THROUGH
THE RIDGE AXIS OVER CENTRAL/NORTHEASTERN MONTANA. THIS FEATURE IS
FORECAST TO TURN MORE EASTERLY ACROSS SOUTHERN SASKATCHEWAN THIS
MORNING...THEN MOVE ALONG THE INTERNATIONAL BORDER THIS AFTERNOON.
ASSOCIATED SHOWERS AND THUNDERSTORMS NOW OVER NORTHEASTERN MONTANA
ARE PROJECTED TO MOVE INTO NORTHWEST NORTH DAKOTA BETWEEN 09-11Z.
WILL ALSO NEED TO KEEP AN EYE ON ANOTHER AREA OF MORE ROBUST
THUNDERSTORMS SOUTH OF GLASGOW NEAR THE CENTER OF A SFC LOW. THEIR
CURRENT TRACK WOULD MISS ND...BUT WILL NEED TO MONITOR FOR
ADDITIONAL DEVELOPMENT OR CHANGE IN DIRECTION.
SURFACE LOW PRESSURE LINGERS OVER EASTERN MONTANA
TODAY...RESULTING IN STRONG WAA ACROSS THE DAKOTAS ALONG WITH
INCREASING LOW LEVEL MOISTURE. 12Z MODELS PROJECT 925MB
TEMPERATURES OVER 34C ACROSS MY SOUTHWEST CORNER...AND THE 32C
ISOTHERM EXTENDING TO JUST SOUTH OF HIGHWAY 2 AND AS FAR EAST AS
THE JAMES RIVER VALLEY. BASED ON YESTERDAYS TEMPERATURES...THE
925MB TEMPS DEPICTED WILL SUPPORT MID/UPPER 90S ACROSS ALL OF
SOUTHWEST AND SOUTH CENTRAL NORTH DAKOTA. COOLER NORTH ALONG TO
NORTH OF HIGHWAY 2 WHERE THE WA WILL NOT BE AS STRONG AND SKIES
ARE EXPECTED TO BE CLOUDIER. MID/UPPER 90S COUPLED WITH SFC
DEWPOINTS IN THE LOW TO MID 60S (POTENTIALLY UPPER 60S) WILL
RESULT IN WIDESPREAD HEAT INDEX VALUES BETWEEN 95-100F. WHILE ONLY
A FEW AREAS ACTUALLY REACH OR EXCEED 100F...OPTED TO ISSUE A HEAT
ADVISORY FOR TODAY ACROSS THE SOUTHERN TWO-THIRDS OF THE CWA DUE
TO THE LATENESS OF THE HEAT...YOUTH ACTIVITIES IN FULL SWING...AND
SEVERAL MAJOR OUTDOOR EVENTS TAKING PLACE TODAY.
PRECIPITATION/THUNDERSTORM CHANCES WILL BE CONFINED TO MY
NORTHWEST AND NORTH CENTRAL THIS MORNING THROUGH 20Z THIS
AFTERNOON NEAR THE BETTER FORCING ASSOCIATED WITH THE EMBEDDED
WAVE.
STILL UNSURE WHAT WILL MATERIALIZE IN THE MID TO LATE AFTERNOON
HOURS. THE ABOVE MENTIONED S/WV WILL HAVE MOVED INTO NORTHEASTERN
NORTH DAKOTA BY THE LATE AFTERNOON...WITH NO OTHER DISTINGUISHABLE
TRIGGER INDICATED BY THE MOST RECENT GUIDANCE. HIGH RESOLUTION 4KM
WRF AND THE NCEP NESTED NAM SEEM TO BE PICKING UP ON THIS AND ARE
MAINLY DRY THROUGH EARLY EVENING. THUS KEPT POPS AT SLIGHT CHANCE
UNTIL LATER THIS EVENING WHEN PERHAPS WE WILL SEE A BIT BETTER
LOW LEVEL FORCING WITH INCREASING OVERRUNNING FLOW AHEAD OF THE
SFC LOW.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 409 AM CDT FRI SEP 6 2013
AN ACTIVE WEATHER PATTERN IS STILL FORECAST FOR THE WEEKEND. A
DRYING TREND IS EXPECTED MONDAY THROUGH THE REMAINDER OF THE PERIOD.
AN UPPER LEVEL LOW CURRENTLY OVER THE PACIFIC NORTHWEST IS PROGGED
TO GRADUALLY TRAVERSE THE NORTHERN ROCKIES SATURDAY THROUGH SUNDAY.
INCREASING MOISTURE COMBINED WITH SHORTWAVES EMANATING FROM THE LOW
WILL LEAD TO INCREASING PRECIP CHANCES FROM WEST TO EAST OVER
WESTERN AND CENTRAL NORTH DAKOTA. FOR NOW IT STILL LOOKS LIKE THE
GREATEST SEVERE WEATHER POTENTIAL WILL BE FAVORED ACROSS
SOUTHWESTERN AND SOUTH CENTRAL NORTH DAKOTA LATE SUNDAY
AFTERNOON/EVENING. GIVEN THE POSITION OF THE UPPER LOW...DEEP LAYER
SHEAR IS PROGGED TO RANGE FROM 30-40 KNOTS ACROSS THE ENTIRE STATE.
HOWEVER...INSTABILITY PARAMETERS ARE MAXIMIZED (MUCAPE VALUES
GREATER THAN 1000 J/KG) SOUTHWEST OF THE MISSOURI RIVER. WILL
CONTINUE TO HIGHLIGHT THIS POSSIBILITY IN THE HWO.
PRECIP CHANCES ARE FORECAST TO DECREASE THROUGH THE DAY MONDAY AS
THE UPPER LEVEL TROUGH AXIS PIVOTS ACROSS THE STATE. THE DRYING
TREND SHOULD CONTINUE THROUGH THE END OF THE PERIOD AS UPPER LEVEL
RIDGING BUILDS OVER THE NORTHERN ROCKIES. TEMPERATURES ARE FORECAST
TO REMAIN ABOVE NORMAL THROUGH THE PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1234 PM CDT FRI SEP 6 2013
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. ISOLATED SHOWERS
WILL MOVE ACROSS CENTRAL NORTH DAKOTA THIS AFTERNOON.
PRECIPITATION CHANCE INCREASE ON SATURDAY WITH SURFACE FLOW
TURNING NORTHEAST TO EAST ACROSS THE AREA. FOR NOW KEPT MID AND
HIGH LEVEL VFR CLOUDINESS WITH VCSH...AS PRECIPITATION CHANCES
WILL BE BETTER BEYOND THE TAF PERIOD.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY UNTIL 9 PM CDT /8 PM MDT/ THIS EVENING FOR
NDZ017>023-025-031>037-040>048-050-051.
&&
$$
UPDATE...TWH
SHORT TERM...NH
LONG TERM...TM
AVIATION...TWH
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
817 PM CDT SAT SEP 7 2013
.UPDATE...
OVERALL FORECAST IS IN FAIR SHAPE AND DONT EXPECT TO MAKE ANY
MAJOR CHANGES. SMALL COMPLEX OF STORMS OVER NORTHWEST SOUTH DAKOTA
MAY BE ABLE TO HOLD TOGETHER AS NOCTURNAL LLJ DEVELOPS THUS AND
MAKE IT INTO MY WESTERN CWA. EAST OF THE MO RVR IS A TOUGHER CALL
AND REALLY AM NOT SURE IF THE AGGRESSIVE HRRR MODEL IS CORRECT.
FOR NOW WILL STICK WITH SLIGHT CHC POPS EAST OF THE MO RVR AS LLJ
IS NOT EXPECTED TO MIGRATE MUCH IF ANY EAST TNT.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...THROUGH TUESDAY AM
A FEW WEAK...ELEVATED SHOWERS PASSING THROUGH THE CWA THIS
PM...MAINLY ACROSS THE NORTHERN TIER ALL THANKS TO A SHORTWAVE
MOVING THROUGH NORTH DAKOTA. ATMOSPHERE OVER THE CWA IS MARGINALLY
UNSTABLE...SO WILL LEAVE IN LOW POPS...AGAIN FOR THE NORTHERN
TIER. FOCUS SHIFTS WEST...WITH ANOTHER WEAK WAVE LIFTING OUT OF
WYOMING. A 20-25KT LOW LEVEL JET WILL DEVELOP IN RESPONSE TO THIS
FEATURE...WITH THE FOCUS IN FAR NORTHWEST SOUTH DAKOTA/WESTERN
NORTH DAKOTA. WILL CONTINUE LOW POPS FOR FAR NORTHWEST COUNTIES IN
CASE ANYTHING ELEVATED MANAGES TO TRICKLE INTO THE CWA. A LEE
LOW/INVERTED TROF FORMS OVER CENTRAL SOUTH DAKOTA ON SUNDAY. VERY
WARM MID LEVEL AIR...WITH H7 TEMPERATURES UPWARDS OF +15C MOVES
INTO CENTRAL SOUTH DAKOTA...THOUGH TEMPERATURES ACROSS THE
NORTHERN AND WESTERN PERIPHERY OF THE CWA ARE COOLER. STEEP LAPSE
RATES AND WIND SHEAR ABOVE THE MIXED LAYER SUGGEST THE POTENTIAL
FOR SEVERE STORMS...THE MAIN QUESTION BEING HOW FAR NORTH AND WEST
DOES THE ELEVATED MIXED LAYER EFFECTIVELY CAP CONVECTION...AND
JUST HOW FAR UNDER THAT CAP WILL THE SURFACE BOUNDARY SET UP. AT
THIS POINT...THINKING IS THE CAP WILL HOLD...AND ANY CONVECTION
THAT FIRES WILL EITHER BE ELEVATED OR VERY SHORT LIVED. BETTER
CHANCES ARE EXPECTED AS THE SHORTWAVE GETS CLOSER TO THE CWA AND A
NEARLY 50KT LOW LEVEL JET SET UP OVER THE CWA. STORMS WOULD LIKELY
FORM ALONG THE NORTHERN PERIPHERY OF THE CWA WHERE JET CONVERGENCE
IS GREATEST...WITH AN EAST/NORTHEAST MOTION. THE SURFACE FRONT
WILL TAKE THROUGH MOST OF MONDAY TO EXIT THE CWA...WITH WEAK COLD
ADVECTION AND GOOD MIXING IN ITS WAKE...EXPECT TEMPERATURES TO
JUMP ABOVE NORMAL AGAIN FOR HIGHS MONDAY. ADVECTION IS NEUTRAL SO
TEMPERATURES TUESDAY ABOUT THE SAME AS MONDAY.
.LONG TERM...TUESDAY THROUGH SATURDAY
MOST OF THE EXTENDED PERIOD LOOKS TO BE QUIET UNTIL THE FRIDAY AND
SATURDAY TIME FRAME. TUESDAY STARTS OFF WITH NORTHWEST FLOW ALOFT
AND DRY CONDITIONS AS THERE IS A LACK OF EMBEDDED WAVES IN THE
UPPER LEVELS. SFC HIGH PRESSURE THEN BEGINS BUILDING SOUTH INTO
THE AREA BY THURSDAY...BRINGING COOLER TEMPERATURES. AFTER HIGHS
IN THE 80S TUESDAY AND WEDNESDAY...HIGHS SHOULD SLIP BACK INTO THE
70S FOR THURSDAY. MODELS THEN SHOW SHORTWAVE ENERGY MOVING INTO
THE WESTERN DAKOTAS ON FRIDAY...WITH THE WAVE TRACKING ACROSS THE
REST OF THE DAKOTAS FRIDAY NIGHT INTO SATURDAY MORNING. A SFC COLD
FRONT SHOULD THEN MOVE EAST ACROSS THE AREA AT SOME POINT SATURDAY
INTO SATURDAY EVENING. ALL THIS LEADS TO CHANCES FOR SHOWERS AND
STORMS...INITIALLY ACROSS WESTERN AND CENTRAL SOUTH DAKOTA
FRIDAY...THEN FOR THE REMAINDER OF THE AREA FRIDAY NIGHT AND
SATURDAY.
&&
.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
EXCEPT FOR A CHANCE OF MVFR FOG LATE TNT...IT SHOULD BE MOSTLY
VFR AT ALL TERMINALS THROUGH SUNDAY. A FEW SHOWERS/STORMS MAY MAKE
THEIR WAY INTO KMBG AROUND MIDNIGHT. MORE STORMS WILL BE POSSIBLE
TOWARD SUNDAY EVENING AT KMBG.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...TDK
SHORT TERM...CONNELLY
LONG TERM...TMT
AVIATION...TDK
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1241 PM CDT FRI SEP 6 2013
.DISCUSSION...
18Z TAF DISCUSSION IN AVIATION SECTION.
&&
.AVIATION...
KCLL/KUTS/KCXO...MAINLY KEEP CONVECTION OUT OF TAFS EXCEPT FOR
CXO. THINK THERE IS A SMALL CHANCE A FEW SHRA/TSRA COULD DEVELOP
BUT NOT ENOUGH CONFIDENCE TO PUT IN TAFS. CXO JUST FAR ENOUGH
SOUTH IN BETTER MOISTURE TO NEED VCTS THIS AFTERNOON. OTHERWISE
EXPECT VFR CIGS. KCXO MAY HAVE 3-4SM VSBY IN THE MORNING FOR MVFR
CIGS. TOMORROW LOOKS LIKE A REPEAT OF TODAY BUT COULD HAVE MORE
HIGH CLOUDS WITH SHORT WAVE TROUGH COMING INTO NE TX.
KIAH/KHOU/KSGR...CONVECTION WORKING UP FROM THE SE SHOULD AFFECT
THESE TERMINALS THIS AFTERNOON WITH RE-DEVELOPMENT ALONG SEA
BREEZE/OUTFLOW BOUNDARIES. WILL KEEP VCTS UNTIL EARLY EVENING AS
ACTIVITY SHOULD BE COMING TO AN END PER LATEST HRRR MODEL RUNS.
SHOULD HAVE VFR CIGS OVERNIGHT AND LOOKS LIKE TOMORROW WILL BE
SIMILAR TO TODAY.
KLBX/KGLS...CONVECTION HAS MOVED BY SO NOT EXPECT MUCH IN THE WAY
OF SHRA/TSRA AFTER 19/20Z TODAY. MAY GET SOME 3-4SM VSBY AT KLBX
IN THE MORNING HOURS WITH WET GROUNDS DUE TO RAIN AND GOOD
RADIATIONAL COOLING OVERNIGHT. PLENTY OF MOISTURE STILL LINGERING
AROUND SO WILL GO WITH VCSH IN THE MORNING HOURS WITH CONVECTION
MOVING OFF THE GULF AGAIN.
39
&&
.PREV DISCUSSION... /ISSUED 1109 AM CDT FRI SEP 6 2013/
DISCUSSION...
SO FAR...THINGS LOOKING A LOT LIKE YESTERDAY. RADAR INDICATING A
DECENT AMOUNT OF COVERAGE OVER THE COASTAL WATERS AND HINTS THAT
ACTIVITY WILL BE INCREASING OVER INLAND AREAS SHORTLY. SOUNDINGS
SUPPORTIVE OF SCT TSRA TODAY AND PERHAPS SLIGHTLY STRONGER STEER-
ING CURRENTS THAN FROM DAYS PAST. THIS SHOULD LESSEN THE CHANCES
OF LOCALLY HEAVY RAINS THROUGH THIS EVENING. THE CURRENT FCST OF
HIGHEST POPS CLOSER TO THE COAST LOOKS GOOD. NO MAJOR CHANGES IN
THE OFFING ATTM. 41
PREV DISCUSSION... /ISSUED 420 AM CDT FRI SEP 6 2013/
00Z SOUNDINGS SHOW PW VALUES NEAR 2.3 INCHES AT KLCH AND 2.0
INCHES NEAR KCRP. IT IS CONSIDERABLY DRIER TO THE NORTH WITH KSHV
REPORTING A PW OF 1.14 INCHES. 850 MB MOISTURE STILL LOOKS RATHER
PLENTIFUL WITH 850 MB DEW PTS AROUND 14 C OVER SE TX. 700 MB
MOISTURE ALSO LOOKS RATHER STOUT WITH WITH DEW PT VALUES AROUND 8
C. THERE ALSO LOOKS TO BE A WEAK 700 MB TROUGH AXIS THAT LIES
NORTH TO SOUTH ACROSS EAST TEXAS. BOTH THE GFS AND ECMWF SHOW A
VORT LOBE ROTATING ACROSS SE TX THIS AFTERNOON FROM THE NORTH.
FEEL THE COMBINATION OF THE VORT...DAYTIME HEATING...WEAK 700 MB
BOUNDARY AND DEEP MOISTURE SHOULD ALLOW FOR A DECENT CHANCE OF
SHRA/TSRA THIS AFTERNOON.
PW VALUES LOOK A BIT LOWER ON SATURDAY BUT A STRONG VORT LOBE
WILL ROTATE AROUND THE UPPER RIDGE AND WILL ONCE AGAIN SERVE AS A
CATALYST FOR SHRA/TSRA ON SATURDAY. WILL MAINTAIN CHANCE POPS ON
SATURDAY. PW VALUES FALL FURTHER SUNDAY AND MONDAY BUT THE
POSITION OF THE UPPER RIDGE LOOKS FAR ENOUGH NORTH TO LIMIT
SUBSIDENCE. DAYTIME HEATING SHOULD AGAIN SERVE AS THE CATALYST FOR
A SLIGHT CHANCE OF SHRA/TSRA BOTH DAYS.
TUES-WEDS LOOK RATHER INTERESTING. A STRONG EASTERLY WAVE WILL
APPROACH THE TEXAS COAST EARLY TUESDAY. THE UPPER RIDGE
STRENGTHENS A BIT AND THE POSITION OF THE RIDGE WILL DETERMINE WHO
GETS HEAVY RAIN AND WHO STAYS DRY. THE GFS IS WEAKER AND FURTHER
NORTHEAST WITH THE RIDGE WHILE THE ECMWF IS STRONGER AND FURTHER
SOUTHWEST. PW VALUES CLIMB TO 2.2 INCHES AND FCST SOUNDINGS LOOK
SATURATED. MOISTURE SHOULD CONTINUE TO STREAM INTO SE TX ON THE
BACK SIDE OF THE UPPER RIDGE AND GIVE SE SE TX A GOOD CHANCE OF
RAIN TUES INTO WED. IF THE GFS IS CORRECT WITH THE POSITION OF THE
UPPER RIDGE...SE TX WILL HAVE HIGH RAIN CHANCES BOTH TUES/WED
BEFORE DRIER AIR WORKS INTO THE REGION ON THURSDAY. WITH THE HIGH
MOISTURE CONTENT AND POTENTIAL FOR TRAINING CELLS...THE POTENTIAL
FOR HEAVY RAIN ALSO EXISTS. STILL A GREAT DEAL OF UNCERTAINTY
REGARDING THE POSITION OF THE UPPER RIDGE SO COMPROMISED BETWEEN
THE WETTER GFS AND DRIER ECMWF FOR NOW AND WILL AWAIT BETTER MODEL
CONSENSUS. 43
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 98 75 98 75 98 / 20 20 20 10 20
HOUSTON (IAH) 96 75 95 75 96 / 30 30 30 10 20
GALVESTON (GLS) 89 80 89 80 89 / 30 30 30 20 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...41
AVIATION/MARINE...39
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1011 PM PDT Thu Sep 5 2013
.SYNOPSIS...
The next few days will be stormy with the potential for heavy
rain and thunderstorms. Flash flooding will be a concern tonight,
and Friday. The slow moving low pressure system responsible for
the stormy weather will begin to move out of the region on Sunday.
Monday through Thursday should be warm and will allow the Inland
Northwest to dry out.
&&
.DISCUSSION...
The Severe Thunderstorm Watch has been discontinued Spokane,
Pullman, Moscow, Kellogg, Coeur D`Alene, Moses Lake, Waterville
and Ritzville. RUC analysis shows that the axis of best surface
based (and most unstable) CAPE has shifted north of Interstate 90.
A small threat of severe thunderstorms remains over the far north
Idaho Panhandle and over the northern tier of counties on
Washington. It does appear that the main concern for the remainder
of the night will be excessive rain. Several Flash Flood Warnings
and Flood Advisories are in effect for central Washington
including the burn scar areas around Wenatchee. Storms this
evening have not been able to maintain updrafts long enough to
produce much of a threat for hail or winds. It is possible that
the remaining counties in the severe thunderstorm watch may be
cleared prior to 1 AM, however the jet max advancing toward the
region from Oregon may help storm organization tonight through the
early morning hours. /GKoch
&&
.AVIATION...
00Z TAFS: Very moist and unstable air mass and disturbances rotating
through it have brought significant thunderstorm activity to Eastern
Oregon this afternoon and this will all track to the north and into
Eastern Washington and Northern Idaho this evening and through the
night. In addition to a significant amount of lightning from
thunderstorms they will also bring the potential for very strong and
damaging wind and large hail. The majority if not all of the severe
storm activity should decrease after 8Z Friday. Otherwise VFR
conditions should prevail with exception of localized MVFR ceilings
and visibilities near thunderstorms any any morning stratus/fog that
may form due to the leftover rainfall keeping an abundant source of
moisture at low levels. /Pelatti
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 60 68 55 70 54 74 / 80 70 50 40 30 10
Coeur d`Alene 59 68 54 70 54 74 / 90 70 50 50 30 20
Pullman 58 70 50 71 48 75 / 70 70 30 20 20 10
Lewiston 65 78 58 78 59 80 / 60 60 20 10 20 10
Colville 60 72 53 72 50 78 / 90 100 60 70 30 20
Sandpoint 59 66 52 70 50 72 / 90 90 70 70 50 30
Kellogg 56 67 52 70 53 72 / 90 80 60 50 40 30
Moses Lake 62 74 55 74 54 81 / 90 70 30 30 10 10
Wenatchee 62 72 57 73 57 80 / 100 80 50 30 10 10
Omak 63 72 56 73 56 82 / 100 100 70 50 20 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Flash Flood Watch through Friday afternoon for Northern
Panhandle.
WA...Flash Flood Watch through Friday afternoon for East Slopes
Northern Cascades-Northeast Mountains-Okanogan Highlands-
Okanogan Valley-Waterville Plateau-Wenatchee Area.
&&
$$
FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE
.SYNOPSIS...
ISSUED AT 309 AM CDT FRI SEP 6 2013
WARMER AND MORE HUMID TODAY AND SATURDAY...THEN COOLER AND DRIER
FOR THE LATTER PART OF THE WEEKEND.
THE MAIN WESTERLIES ACRS NOAM WL REMAIN PRIMARILY IN CANADA DURING
THE PERIOD...WITH A RIDGE IN THE W AND A TROF IN THE E. A WEAKER
SRN STREAM WL BE ACRS THE NRN CONUS. THE PRIMARY FEATURE WITHIN
THIS STREAM WL BE REMNANTS OF PAC NW CUTOFF THAT WL BE SLOWLY
MIGRATING EWD ACRS THE NRN STATES DURING THE PERIOD. FARTHER S...
THE SUBTROPICAL RIDGE WL DOMINATE THE SRN 1/2 OF THE U.S. DURING
THE PERIOD.
OVERALL...THIS IS A PRETTY WARM PATTERN FOR EARLY SEPTEMBER. TEMPS
AND HUMIDITIES WL RESPOND TO THE PASSAGE OF FRONTAL SYSTEMS ACRS
THE AREA...WITH RATHER HUMID CONDITIONS AND WELL ABV NORMAL TEMPS
EXPECTED AHEAD OF EACH COLD FRONT...AND DRIER AIR WITH NR NORMAL
TEMPS AFTER FROPA. PCPN AMNTS ARE TOUGH TO GAUGE. THERE WL BE
SEVERAL OPPORTUNITIES FOR PCPN...THOUGH AT THIS POINT NONE OF THEM
SEEM EXCEPTIONALLY FAVORABLE FOR WIDESPREAD SIG PCPN. AND GIVEN
THE VERY WARM TEMPS ALOFT...CAPPING MAY LIMIT THE PCPN POTENTIAL
WITH THE FROPAS. HUNCH IS THAT MOST AREAS WL END UP SOMEWHAT BLO
NORMAL FOR THE PERIOD...BUT A FEW LOCATIONS WL REPEATEDLY BE HIT
BY CLUSTERS OF TSTMS AND GET ABV NORMAL AMNTS.
&&
.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 309 AM CDT FRI SEP 6 2013
MAIN FCST ISSUE IS PCPN CHCS. THE AIR ACRS THE FCST AREA WAS
STILL QUITE DRY EARLY THIS MORNING...THOUGH MUCH MORE HUMID AIR
WAS JUST TO THE W. SLY FLOW OUT OF THE RECEDING HIGH WON/T BE
FAVORABLE FOR THE HUMID AIR TO THE W TO JUST WASH EWD INTO THE
AREA...THOUGH HUMIDITIES WL CREEP UPWARD DURING THE AFTN. STILL
GETTING MIXED SIGNALS ABOUT THE POSSIBILITY OF PCPN THIS AFTN.
OVERALL...MODELS WERE LUKE WARM AT BEST IN GENERATING PCPN. EVEN
ECMWF HAS BACKED OFF...BUT NOT COMPLETELY GIVEN UP ON...THE PCPN
ACRS THE N THIS AFTN. STLT IMAGERY DID INDICATE A SHRTWV HEADING
SE FM THE LAKE WINNIPEG RGN. THAT FEATURE WAS GENERATING SML
CLUSTERS OF TSRA AT TIMES OVERNIGHT...AND SHOULD ARRIVE IN OUR
AREA DURING PEAK HEATING. SO KEPT CHC POPS ACRS THE N DURING THE
AFTN. EVEN IF TSTMS DEVELOP...COVERAGE WL PROBABLY BE QUITE
LIMITED. STAYED CLOSE TO PREV FCST FOR MAX TEMPS.
LLJ WL STRENGTHEN AND VEER INTO THE AREA TNGT. SO EXPANDED POPS TO
COVER THE ENTIRE AREA DURING THE EVENING. CHC FOR GETTING TSTMS
TNGT IS PROBABLY BETTER THAN THIS AFTN...THOUGH COVERAGE AGAIN
SEEMS LIKE IT WL BE LIMITED.
CANADIAN COLD FRONT SHOULD REACH THE NW PART OF THE FCST AREA SAT
MORNING...THEN SLIDE SEWD ACRS THE AREA DURING THE DAY. FCST
SOUNDINGS OFF THE NAM SHOWED CONSIDERABLE INSTABILITY...THOUGH SFC
TEMPS NEVER GET WARM ENOUGH TO REMOVE ALL THE CIN. WITH A SIMILAR
SITN A WEEK OR TWO AGO...ENDED UP WITH THE BULK OF THE CONVECTION
FORMING BACK OVER THE FRONTAL SURFACE AND FALLING ON THE COOL SIDE
OF THE FRONT. FOR THAT REASON...LINGERED POPS BEHIND THE FRONT.
THE FRONT WON/T ARRIVE IN THE SRN PART OF THE FCST AREA UNTIL LATE
IN THE DAY...SO TEMPS COULD APPROACH 90F IN THE TYPICAL HOT SPOTS.
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 309 AM CDT FRI SEP 6 2013
THE COLD FRONT WILL MOVE AWAY FROM THE AREA SATURDAY EVENING.
MODELS TONIGHT ARE SHOWING GUSTY NORTHEAST WINDS BEHIND THE FRONT
THAT WILL USHER IN THE COOLER AIR. WITH BOUNDARY LURKING ACROSS
EAST CENTRAL WISCONSIN AT 00Z...CONSIDERED ADDING A SMALL CHANCE
OF SHOWERS AND STORMS FOR A FEW HOURS INTO THE EVENING UNTIL
BOUNDARY IS WELL SOUTH OF THE AREA. DID NOT WANT TO FLIP FLOP AT
THIS POINT SINCE DAY SHIFT REMOVED THE MENTION OF SHOWERS AND
STORMS.
SUNDAY WILL BE PLEASANT WITH HIGHS IN THE UPPER 60S TO LOWER 70S
WITH DEW POINTS IN THE MIDDLE 40S TO LOWER 50S UNDER MOSTLY SUNNY
SKIES. MAIN CONCERN FOR SUNDAY NIGHT WILL BE HOW QUICK RETURN FLOW
PRECIPITATION DEVELOPS ACROSS THE NORTHERN PLAINS/WESTERN LAKES.
THE ECMWF WAS THE MOST AGGRESSIVE IN BRINGING PRECIPITATION INTO
OUR AREA WHILE GFS/WRF WERE CONSIDERABLY SLOWER. SINCE ECMWF HAS
BEEN JUMPING ACROSS WITH ITS SOLUTION...DECIDED TO CONTINUE THE
SLOWER TREND IN THE ARRIVAL OF THE PRECIPITATION. ON
MONDAY...ONGOING OR ARRIVING PRECIPITATION FROM THE WEST WILL
BRING A CHANCE OF SHOWERS AND STORMS DURING THE DAY UNTIL WARM
FRONT PUSHES NORTHWARD ACROSS THE AREA. HAVE TEMPERED MAX
TEMPERATURES ON MONDAY DUE TO ON GOING PRECIPITATION AND CLOUD
COVER...BUT COULD BE CONSIDERABLY WARMER IF CLOUDS AND RAIN END
QUICKLY MONDAY MORNING.
MANY QUESTIONS LINGER FOR SHOWERS AND STORMS MONDAY NIGHT INTO
TUESDAY. SOME OF THE MODELS DEVELOP SHOWERS AND STORMS WELL WEST
OF THE AREA MONDAY AFTERNOON AND THE APPROACH THE AREA MONDAY
EVENING. THE BIG QUESTION IS WHAT WILL HAPPEN AFTER MIDNIGHT AS
SOME OF THE MODELS WEAKEN/DISSIPATE THE ACTIVITY BEFORE IT GETS
HERE WHILE THE ECMWF BRINGS A LINE ACROSS TUESDAY MORNING. ON
TUESDAY...SOME OF THE MODELS BRING THE FRONT THROUGH THE
MORNING...WHICH CLIMATOLOGICALLY IS NOT A FAVORED TIME OF THE DAY
FOR SEVERE WEATHER. THE ECMWF WOULD SUGGEST REDEVELOPMENT ACROSS
CENTRAL AND EAST CENTRAL WISCONSIN TUESDAY AFTERNOON. TOO EARLY TO
DETERMINE WHICH SCENARIO WILL PAN OUT...THUS WILL KEEP VAGUE
WORDING IN THE HAZARDOUS WEATHER OUTLOOK AT THIS TIME.
BEYOND TUESDAY...LITTLE RIPPLES IN THE NORTHWEST FLOW PATTERN
COULD BRING A SMALL CHANCE OF SHOWERS OR STORMS WEDNESDAY INTO
THURSDAY. SUNDAY WILL BE SEASONABLE WITH LOWER HUMIDITY. WARM AND
HUMID CONDITIONS WILL RETURN TO THE AREA FOR MONDAY/TUESDAY.
COOLER TEMPERATURES RETURN TO THE AREA ON WEDNESDAY.
&&
.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 309 AM CDT FRI SEP 6 2013
GENERALLY VFR CONDITIONS EXPECTED THROUGHOUT THE PERIOD. SOME
LINGERING LOW-LEVEL MOISTURE ACRS THE WRN PART OF THE AREA COULD
RESULT IN A BRIEF PERIOD OF MVFR CIGS ACRS THAT AREA AS TEMPS
START TO WARM THIS MORNING. NOT SURE YET WHETHER OR NOT THAT
POSSIBILITY WARRANTS INCLUSION WITH A TEMPO GROUP IN THE 12Z TAFS.
WL MAKE ISSUANCE TIME DECISION BASED ON STLT AND RAP FCST
SOUNDINGS.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS.......SKOWRONSKI
SHORT TERM.....SKOWRONSKI
LONG TERM......ECKBERG
AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS TAUNTON MA
417 AM EDT SUN SEP 8 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS SOUTHERN NEW ENGLAND TODAY AND MAY BE
PRECEDED BY A BRIEF SHOWER. HIGH PRESSURE WILL BRING COOLER
WEATHER TONIGHT AND MONDAY. WARMER AND MORE HUMID WEATHER WILL
RETURN BY MIDWEEK AS THIS HIGH BECOMES CENTERED OFFSHORE. ANOTHER
COLD FRONT MAY BRING SHOWERS AND THUNDERSTORMS LATER THIS WEEK
BEFORE ANOTHER HIGH PRESSURE RETURNS FOR NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
3 AM UPDATE...
SMALL BAND OF SPRINKLES WAS PUSHING SOUTHWARD THROUGH REGION EARLY
THIS MORNING...ASSOCIATED WITH WEAK SURFACE TROUGH. EXPECT THIS
BAND TO DIMINISH AS IT REACHES S COAST PER HRRR. MEANWHILE NOT
MUCH HAPPENING UPSTREAM WITH COLD FRONT WHICH EXTENDED FROM
WESTERN AND NORTHERN NY INTO NORTHERN NEW ENGLAND. HRRR SEEMS TO
HAVE CORRECTLY BACKED OFF ON AREAL EXTENT OF SHOWERS AS FRONT
REACHES SOUTHERN NEW ENGLAND THIS MORNING...SO AM ONLY MENTIONING
ISOLATED SHOWERS AS ANY ACTIVITY WILL BE WIDELY SCATTERED.
FRONT SHOULD PUSH OFF S COAST EARLY THIS AFTERNOON. FAIRLY STRONG
COLD ADVECTION ASSOCIATED WITH HIGH PRESSURE BUILDING IN FROM
GREAT LAKES WILL RESULT IN A FEW HOURS OF BREEZY CONDITIONS LATER
THIS AFTERNOON...ESPECIALLY NEAR COAST. CLEARING WILL ALSO SET IN
FROM NW TO SE AS DRIER AIR ARRIVES.
GFS/NAM MOS ARE AT ODDS WITH EACH OTHER TODAY WITH NAM RUNNING
SEVERAL DEGREES WARMER AND GFS SEEMING TO BE TOO LOW CONSIDERING
AFTERNOON CLEARING. STAYED WITH CURRENT FORECAST OF HIGHS IN 60S
AND 70S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
WINDS DIMINISH QUICKLY THIS EVENING AS GRADIENT WEAKENS IN
RESPONSE TO HIGH PRESSURE BECOMING CENTERED OVER PA OVERNIGHT. DRY
AIRMASS IN PLACE WILL ALLOW FOR IDEAL RADIATIONAL COOLING.
CERTAINLY CAN SEE USUAL COLD SPOTS DROPPING INTO UPPER 30S BUT
WIDESPREAD MID 30S MAY BE A STRETCH...SO AM NOT ISSUING ANY FROST
ADVISORIES AT THIS TIME IN COLLABORATION WITH ALY/GYX. OTHERWISE A
CHILLY NIGHT AHEAD WITH LOWS IN 40S TO AROUND 50.
PLENTY OF SUNSHINE EXPECTED MON AS AIRMASS REMAINS DRY THROUGH
COLUMN PER MODEL CROSS SECTIONS. HIGH PRESSURE GRADUALLY HEADS
OFFSHORE RESULTING IN LIGHT S/SW FLOW...BUT NOT SOON ENOUGH TO
PREVENT SEA BREEZE DEVELOPMENT NEAR E MA COAST. LEANED CLOSER TO
GFS MOS FOR HIGHS /UPPER 60S COAST AND LOWER 70S INLAND/ WHICH
SEEMED MORE REASONABLE.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
* A RETURN TO HEAT AND HUMIDITY MID WEEK
* CHANCE OF THUNDERSTORMS AS A COLD FRONT MOVES THROUGH THU-FRI
08/00Z MODELS REMAIN IN ABOVE AVERAGE AGREEMENT THROUGH THIS
PORTION OF THE FORECAST. THERE ARE SOME DIFFERENCES WITH THE
TIMING OF A COLD FRONT LATER THIS WEEK...AS WELL AS HOW ACTIVE A
PREFRONTAL TROUGH WILL BE AROUND WEDNESDAY. WILL GENERALLY FOLLOW
THE CONSENSUS TIMING...WITH SOME TWEAKS DETAILED BELOW.
MONDAY NIGHT-TUESDAY...A WARM FRONT APPROACHES OUR REGION WITH A
HIGH PRESSURE CENTERED SOUTH OF NOVA SCOTIA. MID AND HIGH LEVEL
CLOUDS SHOULD MOVE IN. TEMPERATURES EXPECTED TO BE RIGHT AROUND
NORMAL FOR SEPTEMBER.
TUESDAY...A WARM FRONT MOVES NORTHWARD THROUGH SOUTHERN NEW
ENGLAND...WITH A RETURN TO WARMER SOUTHWEST FLOW AT THE SURFACE.
TEMPERATURES WILL START WARMING TO ABOVE NORMAL. WITH THE ADDED
MOISTURE IN THE ATMOSPHERE AND THE HEATING AT THE SURFACE...
EXPECTING SOME DIURNAL CLOUDS TO DEVELOP. 08/00Z ECMWF CONTINUES
THE TREND FROM ITS PREVIOUS RUN AND IS MUCH MORE AGGRESSIVE THAN
THE OTHER GUIDANCE DEVELOPING SHOWERS. WITH THE BEST DYNAMICS
LIKELY REMAINING TO OUR NORTH AND WEST...THINK THIS MODEL IS
OVERDONE. THINKING MORE ALONG THE LINES OF ISOLATED TO SCATTERED
SPRINKLES AT THIS POINT.
WEDNESDAY...THERE START TO BE SOME TIMING DIFFERENCES HERE IN THE
MODELS REGARDING THE ONSET OF SHOWERS AND THUNDERSTORMS ACROSS THE
REGION. THE GFS STARTS EXHIBITING SOME QPF WEDNESDAY AFTERNOON
ACROSS THE NORTHWESTERN ZONES AND THEN BUILDING EASTWARD THROUGH THE
AREA THROUGH WEDNESDAY NIGHT. THE ECMWF KEEPS THIS DAY DRY AND
STARTS MOVING SHOWERS INTO THE NORTHWESTERN ZONES LATE WEDNESDAY
NIGHT...KEEPING THE BULK OF THE RAINFALL TO THURSDAY.
WHILE THERE SHOULD BE A PREFRONTAL TROUGH NEARBY...THERE IS STILL
NOT A LOT OF SYNOPTIC SUPPORT OR INSTABILITY. MID LEVEL LAPSE
RATES IN THE GFS ARE A LITTLE MORE UNSTABLE THAN MOIST ADIABATIC.
WILL WE CANNOT RULE SOME ISOLATED SHOWERS OR THUNDERSTORMS...
LEANING AWAY FROM THE WIDESPREAD DOWNPOURS DEPICTED BY THE GFS.
THIS WILL BE THE WARMEST...AND LIKELY THE MOST HUMID...DAY OF THIS
WEEK.
THURSDAY...ANOTHER WARM DAY WITH UNCOMFORTABLE DEWPOINTS. A COLD
FRONT IS EXPECTED THURSDAY NIGHT INTO FRIDAY MORNING. DEPENDING
ON ITS TIMING...STRONG THUNDERSTORMS ARE A RISK AGAIN THURSDAY WITH
A SURFACE TROUGH AHEAD OF THE FRONT INDUCING SURFACE CONVERGENCE
AND DESTABILIZATION. ALSO...AMPLE CAPE...BORDERLINE SHEAR AND
DECENT SEVERE PARAMETERS SHOULD EXIST. THE BIG QUESTION...ALONG
WITH FRONTAL TIMING...IS CLOUD COVER. IT MAY BE TOO CLOUDY TO
GENERATE MUCH SURFACE DESTABILIZATION.
FRIDAY-SATURDAY...ANY LEFTOVER SHOWERS EXIT OFF THE COAST FRIDAY
MORNING WITH THE FRONT AND A HIGH PRESSURE TAKES ITS PLACE.
SATURDAY MORNING SHOULD START ANOTHER PERIOD OF BELOW NORMAL
TEMPERATURES. THE MOIST AIR SHOULD LEAVE WITH THE COLD FRONT AS
THIS HIGH PRESSURE BRINGS IN DRIER CONDITIONS.
&&
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH MONDAY/...HIGH CONFIDENCE.
PATCHY MVFR/IFR THROUGH 12Z IN FOG...MAINLY IN CT RIVER VALLEY OF
MA/NH. OTHERWISE VFR CIGS AOA 060 THROUGH THIS MORNING WITH
SCATTERED SPRINKLES...PROBABLY NOT ENOUGH TO WET RUNWAYS.
CLEARING THIS AFTERNOON FROM NW TO SE WITH INCREASING N/NW WINDS
GUSTING TO 20-25KT. STRONGEST GUSTS ALONG COAST 21Z-03Z BEFORE
WINDS SUBSIDE. ONCE AGAIN PATCHY FOG WILL BRING LOCAL MVFR/IFR TO
INTERIOR VALLEYS.
VFR MON. SEA BREEZES EXPECTED NEAR E MA COAST 15Z-23Z BEFORE WINDS
BECOME S/SW. SHOULD SEE S/SW WINDS ALL DAY NEAR S COAST.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK...TUESDAY THROUGH THURSDAY...
TUESDAY...HIGH CONFIDENCE. MAINLY VFR. LOW PROBABILITY OF
MVFR/IFR CONDITIONS IN FOG DURING THE OVERNIGHT.
WEDNESDAY AND THURSDAY...MODERATE CONFIDENCE. MAINLY VFR. MODERATE
PROBABILITY OF MVFR/IFR CONDITIONS IN SHRA/TSRA/FG FROM WEDNESDAY
NIGHT INTO THURSDAY.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT TERM /THROUGH MONDAY/...HIGH CONFIDENCE.
EXPANDED SCA TO INCLUDE ALL WATERS EXCEPT NARRAGANSETT BAY FROM
THIS AFTERNOON INTO TONIGHT. WINDS DIMINISH THIS EVENING BUT SEAS
ON OUTER WATERS WILL TAKE MORE TIME TO SUBSIDE BELOW 5 FT.
COLD FRONT CROSSES WATERS LATER THIS MORNING AND EARLY THIS
AFTERNOON WITH NOTHING MORE THAN BRIEF SHOWER. LIGHT W/SW WINDS
AHEAD OF FRONT SHIFT TO N/NW WITH PERIOD OF 25KT GUSTS EXPECTED
FROM MID AFTERNOON THROUGH EARLY TONIGHT...ESPECIALLY ON E MA
WATERS AND AROUND CAPE COD.
TIMING OF HIGHER GUSTS ON BUZZARDS BAY AND VINEYARD SOUND WILL
COINCIDE WITH INCOMING TIDE AGAINST N WIND /LOW TIDE AROUND 4 PM
AND HIGH TIDE AROUND 1030 PM/. THIS WILL RESULT IN STEEP WAVES
LATER THIS AFTERNOON AND ESPECIALLY THIS EVENING. SIMILAR
SITUATION ON CAPE COD BAY WITH DEPARTING TIDE AGAINST N WIND LATER
THIS AFTERNOON /HIGH TIDE AROUND 2 PM AND LOW TIDE AROUND 8 PM/.
HIGH PRESSURE SLOWLY HEADS OFFSHORE MON WITH LIGHT S/SW FLOW...
BUT SEA BREEZE EXPECTED ALONG E MA COAST BEFORE WINDS TURN S
TOWARD EVENING.
OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...
QUIET BOATING WEATHER EXPECTED TUESDAY. SEAS INCREASE TO AROUND
5-6 FEET ACROSS THE OUTER WATERS WEDNESDAY INTO THURSDAY IN
ADVANCE OF A COLD FRONT MOVING TOWARDS THE WATERS. WINDS HAVE THE
POTENTIAL TO GUST TO NEAR 25 KTS EACH AFTERNOON TUESDAY THROUGH
THURSDAY...PARTICULARLY ACROSS THE NEAR SHORE WATERS SURROUNDING
CAPE COD AND THE ISLANDS. THERE IS A LOW PROBABILITY OF SHOWERS
AND THUNDERSTORMS OVER THE WATERS THURSDAY.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT EDT
TONIGHT FOR ANZ231>235-237.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 8 PM EDT THIS
EVENING FOR ANZ230.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM EDT
MONDAY FOR ANZ250.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO MIDNIGHT EDT
TONIGHT FOR ANZ251.
SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EDT MONDAY
FOR ANZ254>256.
&&
$$
SYNOPSIS...JWD/BELK
NEAR TERM...JWD
SHORT TERM...JWD
LONG TERM...BELK
AVIATION...JWD/BELK
MARINE...JWD/BELK
AREA FORECAST DISCUSSION
NWS TAUNTON MA
258 AM EDT SUN SEP 8 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS SOUTHERN NEW ENGLAND TODAY AND MAY BE
PRECEDED BY A BRIEF SHOWER. HIGH PRESSURE WILL BRING COOLER
WEATHER TONIGHT AND MONDAY. WARMER AND MORE HUMID WEATHER WILL
RETURN BY MIDWEEK AS THE HIGH BECOMES CENTERED OFFSHORE. ANOTHER
COLD FRONT MAY BRING SHOWERS AND THUNDERSTORMS LATER THIS WEEK
BEFORE HIGH PRESSURE RETURNS FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
3 AM UPDATE...
SMALL BAND OF SPRINKLES WAS PUSHING SOUTHWARD THROUGH REGION EARLY
THIS MORNING...ASSOCIATED WITH WEAK SURFACE TROUGH. EXPECT THIS
BAND TO DIMINISH AS IT REACHES S COAST PER HRRR. MEANWHILE NOT
MUCH HAPPENING UPSTREAM WITH COLD FRONT WHICH EXTENDED FROM
WESTERN AND NORTHERN NY INTO NORTHERN NEW ENGLAND. HRRR SEEMS TO
HAVE CORRECTLY BACKED OFF ON AREAL EXTENT OF SHOWERS AS FRONT
REACHES SOUTHERN NEW ENGLAND THIS MORNING...SO AM ONLY MENTIONING
ISOLATED SHOWERS AS ANY ACTIVITY WILL BE WIDELY SCATTERED.
FRONT SHOULD PUSH OFF S COAST EARLY THIS AFTERNOON. FAIRLY STRONG
COLD ADVECTION ASSOCIATED WITH HIGH PRESSURE BUILDING IN FROM
GREAT LAKES WILL RESULT IN A FEW HOURS OF BREEZY CONDITIONS LATER
THIS AFTERNOON...ESPECIALLY NEAR COAST. CLEARING WILL ALSO SET IN
FROM NW TO SE AS DRIER AIR ARRIVES.
GFS/NAM MOS ARE AT ODDS WITH EACH OTHER TODAY WITH NAM RUNNING
SEVERAL DEGREES WARMER AND GFS SEEMING TO BE TOO LOW CONSIDERING
AFTERNOON CLEARING. STAYED WITH CURRENT FORECAST OF HIGHS IN 60S
AND 70S.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/...
WINDS DIMINISH QUICKLY THIS EVENING AS GRADIENT WEAKENS IN
RESPONSE TO HIGH PRESSURE BECOMING CENTERED OVER PA OVERNIGHT. DRY
AIRMASS IN PLACE WILL ALLOW FOR IDEAL RADIATIONAL COOLING.
CERTAINLY CAN SEE USUAL COLD SPOTS DROPPING INTO UPPER 30S BUT
WIDESPREAD MID 30S MAY BE A STRETCH...SO AM NOT ISSUING ANY FROST
ADVISORIES AT THIS TIME IN COLLABORATION WITH ALY/GYX. OTHERWISE A
CHILLY NIGHT AHEAD WITH LOWS IN 40S TO AROUND 50.
PLENTY OF SUNSHINE EXPECTED MON AS AIRMASS REMAINS DRY THROUGH
COLUMN PER MODEL CROSS SECTIONS. HIGH PRESSURE GRADUALLY HEADS
OFFSHORE RESULTING IN LIGHT S/SW FLOW...BUT NOT SOON ENOUGH TO
PREVENT SEA BREEZE DEVELOPMENT NEAR E MA COAST. LEANED CLOSER TO
GFS MOS FOR HIGHS /UPPER 60S COAST AND LOWER 70S INLAND/ WHICH
SEEMED MORE REASONABLE.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
* HIGH PRESSURE EARLY IN THE WEEK
* A RETURN TO SUMMER LIKE TEMPERATURES MID WEEK
* CHANCE OF STORMS AS COLD FRONT MOVES THROUGH WED-THU
MODELS ARE IN GOOD AGREEMENT THROUGH MUCH OF THE LONG TERM. AS
USUAL...THERE ARE SOME TIMING DIFFERENCES IN THE LATER PART OF THE
LONG TERM BUT OTHERWISE...EXCELLENT AGREEMENT ON THE GENERAL
SYNOPTIC PATTERN. HIGH PRESSURE EARLY IN THE WEEK WILL MOVE OFFSHORE
ALLOWING A WARM FRONT TO MOVE NORTH THROUGH SOUTHERN NEW ENGLAND.
THIS WILL BRING A RETURN OF SUMMER LIKE HEAT AND HUMIDITY WEDNESDAY
BEFORE A COLD FRONT MOVES THROUGH THURSDAY. THIS SUMMER LIKE
ATMOSPHERE ALSO WILL ALLOW FOR ANOTHER DAY OF SHOWERS AND
THUNDERSTORMS THURSDAY. THEN HIGH PRESSURE MOVES BACK INTO THE
REGION TOWARDS THE END OF THE WEEK...RETURNING TEMPERATURES TO
NORMAL FOR SEPTEMBER.
MONDAY...HIGH PRESSURE MOVES OFFSHORE AS LOW PRESSURE MOVES INTO THE
GREAT LAKES. MUCH OF THE PERIOD WILL BE FAIR...WITH CLOUDS STARTING
TO MOVE IN DURING THE OVERNIGHT WITH A WARM FRONT STARTING TO SURGE
NORTHWARD. TEMPERATURES WILL BE RIGHT AROUND NORMAL FOR SEPTEMBER.
TUESDAY...THE WARM FRONT MOVES NORTHWARD THROUGH SOUTHERN NEW
ENGLAND...WITH A RETURN TO WARMER SOUTHWESTERLY FLOW AT THE SURFACE.
TEMPERATURES WILL START WARMING TO ABOVE NORMAL. WITH THE ADDED
MOISTURE IN THE ATMOSPHERE AND THE HEATING AT THE SURFACE...EXPECT
SOME DIURNAL CLOUDS TO DEVELOP BUT THE AREA SHOULD OTHERWISE REMAIN
DRY.
WEDNESDAY...THERE START TO BE SOME TIMING DIFFERENCES HERE IN THE
MODELS REGARDING THE ONSET OF SHOWERS AND THUNDERSTORMS ACROSS THE
REGION. THE GFS STARTS EXHIBITING SOME QPF WEDNESDAY AFTERNOON
ACROSS THE NORTHWESTERN ZONES AND THEN BUILDING EASTWARD THROUGH THE
AREA THROUGH WEDNESDAY NIGHT. THE ECMWF KEEPS THE DAY DRY AND
STARTS MOVING SHOWERS INTO THE NORTHWESTERN ZONES LATE WEDNESDAY
NIGHT...KEEPING THE BULK OF THE PRECIP TO THURSDAY. THIS WILL BE
THE WARMEST DAY OF THE WEEK...WITH TEMPS INTO THE 80S AND POSSIBLY
NEAR 90.
THURSDAY...A SECOND WARM DAY WITH UNCOMFORTABLE DEWPOINTS. COLD
FROPA IS EXPECTED OVERNIGHT INTO FRIDAY MORNING. DEPENDING ON
TIMING...STRONG THUNDERSTORMS ARE A RISK AGAIN TODAY WITH A
SURFACE TROUGH AHEAD OF THE FRONT INDICATING SURFACE
DESTABILIZATION. ALSO...AMPLE CAPE...BORDERLINE SHEAR AND DECENT
SEVERE PARAMETERS SHOULD EXIST. BIG QUESTION...ALONG WITH FROPA
TIMING...IS CLOUD COVER AS TOO MUCH MAY BE AROUND TO ALLOW FOR
NEEDED SURFACE DESTABILIZATION.
FRIDAY-SATURDAY...ANY LEFTOVER SHOWERS EXIT OFF THE COAST IN THE AM
WITH THE FRONT AND HIGH PRESSURE TAKES ITS PLACE. SATURDAY SHOULD
HAVE COLD MORNING TEMPERATURES FROM THE CANADIAN HIGH PRESSURE
SYSTEM. THE MOIST AIR SHOULD LEAVE WITH THE COLD FRONT AND THE HIGH
SHOULD BRING IN DRIER CONDITIONS.
&&
.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH MONDAY/...HIGH CONFIDENCE.
PATCHY MVFR/IFR THROUGH 12Z IN FOG...MAINLY IN CT RIVER VALLEY OF
MA/NH. OTHERWISE VFR CIGS AOA 060 THROUGH THIS MORNING WITH
SCATTERED SPRINKLES...PROBABLY NOT ENOUGH TO WET RUNWAYS.
CLEARING THIS AFTERNOON FROM NW TO SE WITH INCREASING N/NW WINDS
GUSTING TO 20-25KT. STRONGEST GUSTS ALONG COAST 21Z-03Z BEFORE
WINDS SUBSIDE. ONCE AGAIN PATCHY FOG WILL BRING LOCAL MVFR/IFR TO
INTERIOR VALLEYS.
VFR MON. SEA BREEZES EXPECTED NEAR E MA COAST 15Z-23Z BEFORE WINDS
BECOME S/SW. SHOULD SEE S/SW WINDS ALL DAY NEAR S COAST.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK...TUESDAY THROUGH THURSDAY...
TUESDAY...HIGH CONFIDENCE. MAINLY VFR. LOW PROBABILITY OF
MVFR/IFR CONDITIONS IN FOG DURING THE OVERNIGHT PERIODS.
WEDNESDAY AND THURSDAY...MODERATE CONFIDENCE. MAINLY VFR. MODERATE
PROBABILITY OF MVFR/IFR CONDITIONS IN SHRA/TSRA/FG FROM WEDNESDAY
NIGHT INTO THURSDAY.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT TERM /THROUGH SUNDAY NIGHT/...HIGH CONFIDENCE.
EXPANDED SCA TO INCLUDE ALL WATERS EXCEPT NARRAGANSETT BAY FROM
THIS AFTERNOON INTO TONIGHT. WINDS DIMINISH THIS EVENING BUT SEAS
ON OUTER WATERS WILL TAKE MORE TIME TO SUBSIDE BELOW 5 FT.
COLD FRONT CROSSES WATERS LATER THIS MORNING AND EARLY THIS
AFTERNOON WITH NOTHING MORE THAN BRIEF SHOWER. LIGHT W/SW WINDS
AHEAD OF FRONT SHIFT TO N/NW WITH PERIOD OF 25KT GUSTS EXPECTED
FROM MID AFTERNOON THROUGH EARLY TONIGHT...ESPECIALLY ON E MA
WATERS AND AROUND CAPE COD.
TIMING OF HIGHER GUSTS ON BUZZARDS BAY AND VINEYARD SOUND WILL
COINCIDE WITH INCOMING TIDE AGAINST N WIND /LOW TIDE AROUND 4 PM
AND HIGH TIDE AROUND 1030 PM/. THIS WILL RESULT IN STEEP WAVES
LATER THIS AFTERNOON AND ESPECIALLY THIS EVENING. SIMILAR
SITUATION ON CAPE COD BAY WITH DEPARTING TIDE AGAINST N WIND LATER
THIS AFTERNOON /HIGH TIDE AROUND 2 PM AND LOW TIDE AROUND 8 PM/.
HIGH PRESSURE SLOWLY HEADS OFFSHORE MON WITH LIGHT S/SW FLOW...
BUT SEA BREEZE EXPECTED ALONG E MA COAST BEFORE WINDS TURN S
TOWARD EVENING.
OUTLOOK...TUESDAY THROUGH THURSDAY...
QUIET BOATING WEATHER EXPECTED TUESDAY. SEAS INCREASE TO AROUND
5-6 FEET ON THE OUTER WATERS WEDNESDAY AND THURSDAY IN ADVANCE OF
A COLD FRONT MOVING OVER THE WATERS. WINDS HAVE THE POTENTIAL TO
GUST TO NEAR 25 KTS EACH AFTERNOON TUESDAY THROUGH
THURSDAY...PARTICULARLY ON THE NEAR SHORE WATERS SURROUNDING CAPE
COD AND THE ISLANDS. THERE IS A LOW PROBABILITY OF SHOWERS AND
THUNDERSTORMS OVER THE WATERS ON THURSDAY.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT EDT
TONIGHT FOR ANZ231>235-237.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 8 PM EDT THIS
EVENING FOR ANZ230.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM EDT
MONDAY FOR ANZ250.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO MIDNIGHT EDT
TONIGHT FOR ANZ251.
SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EDT MONDAY
FOR ANZ254>256.
&&
$$
SYNOPSIS...BELK/JWD
NEAR TERM...JWD
SHORT TERM...JWD
LONG TERM...RLG/99
AVIATION...BELK/JWD
MARINE...BELK/JWD
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
520 AM EDT SUN SEP 8 2013
.SYNOPSIS..
09Z WATER VAPOR AND H4 RAP ANALYSIS SHOWING A LARGE AREA OF UPPER
RIDGING OVER THE CENTRAL CONUS BEGINNING TO SPREAD EASTWARD WHILE
THE VERY TAIL END OF WEAK TROUGHING OVER THE WESTERN ATLANTIC
REACHES ALL THE WAY SOUTH AND SOUTHWEST TO THE FLORIDA EAST COAST.
WV IMAGERY INDICATES DEFINED DRYING/SUBSIDENCE IN THE MID/UPPER
LEVELS ADVECTING SOUTHWARD WITHIN THE SYNOPTIC FLOW BETWEEN THESE
TWO FEATURES. THE DRY AIR ALOFT HAS MADE PROGRESS SOUTHWARD INTO THE
NORTHERN FL PENINSULA DURING THE PAST 12-18 HOURS AND NWP GUIDANCE
ALL SUGGEST FURTHER SOUTHWARD PENETRATION THROUGH THE DAYLIGHT HOURS
TODAY.
AT THE SURFACE...GRADIENT IS RATHER RELAXED FOR THE FINAL DAY OF THE
WEEKEND WITH WEAK HIGH PRESSURE TO OUR NORTH. THE FLOW AROUND THIS
RIDGE IS LIGHT EAST TO NORTHEAST UNDER MOSTLY CLEAR SKIES. JUST A
FEW ISOLATED STORMS WELL OFFSHORE THIS MORNING ALONG THE LAND BREEZE
CONVERGENCE ZONE FROM THE PENINSULA AND PANHANDLE. TEMPERATURES ARE
COMFORTABLE FOR EARLY SEPTEMBER WITH SOME INLAND STATIONS TO THE
NORTH OF I-4 DROPPING INTO THE UPPER 60S. THE COOLER TEMPERATURES
ARE ALLOWING FOR SOME PATCHY SHALLOW GROUND FOG WHICH SHOULD BURN
OFF WITHIN AN HOUR OR 2 OF SUNRISE.
&&
.SHORT TERM (TODAY THROUGH TUESDAY)...
TODAY/TONIGHT...
A GENERALLY PLEASANT EARLY SEPTEMBER DAY APPEARS ON TAP FOR MUCH OF
WEST-CENTRAL AND SOUTHWEST FLORIDA. GUIDANCE ENSEMBLES
CROSS-SECTIONS AGREE ON A SOUTHWARD EXPANSION OF DEEP LAYER DRY AIR
ABOVE 700MB THAT HAS ALREADY MADE ITS WAY INTO THE NORTHERN HALF OF
THE FLORIDA PENINSULA...ALONG WITH COINCIDENT SUPPRESSION/ Q-VECTOR
DIVERGENCE. THERE IS A SHALLOW LAYER OF MOISTURE TRAPPED UNDER THIS
LAYER...SO SHOULD SEE THE MOSTLY SUNNY SKIES THIS MORNING GIVE WAY
TO A SHALLOW SCT CU FIELD BY EARLY AFTERNOON. THE DEPTH OF THE DRY
AIR AND SUBSTANTIAL ENTRAINMENT OF LOW THETA-E AIR INTO ANY UPDRAFT
COLUMN SHOULD KEEP ANY DIURNAL CONVECTION ISOLATED IN NATURE FROM
THE TAMPA BAY / I-4 CORRIDOR NORTHWARD THROUGH THE NATURE COAST
ZONES. THE COLUMN OF DRY AIR BECOME SLIGHTLY LESS DEEP THE FURTHER
SOUTH ONE TRAVELS AND RETURN RAIN CHANCES TO THE CHANCE 30-50% RANGE
SOUTH OF TAMPA BAY AND ESPECIALLY DOWN TOWARD FORT MYERS.
HOWEVER...EVEN FOR THESE SOUTHERN ZONES...OVERALL COVERAGE OF STORMS
SHOULD BE LESS THAN PREVIOUS DAYS...AND STORMS THAT DO DEVELOP
SHOULD BE LATE DAY AND BRIEF IN DURATION. ANY CELLS THAT REACH A
SUFFICIENT DEPTH WILL BEGIN TO FIGHT THIS HOSTILE AIRMASS ALOFT AND
HASTEN THEIR DEMISE. TEMPERATURES LOOK SEASONABLE WITH LOWER 90S
COMMON BY MID AFTERNOON.
ANY EVENING STORMS NEAR THE COAST SOUTH OF TAMPA BAY SHOULD EXIT OFF
THE OFFSHORE BY 10-11PM...AND GIVE A GENERALLY DRY OVERNIGHT PERIOD
TO ALL ZONES. THE DRIER COLUMN...MOSTLY CLEAR SKIES AND LIGHT
WINDS...SIMILAR TO AREAS NORTH THIS MORNING...ALLOW TEMPERATURES TO
REACH COMFORTABLE LEVELS FOR EARLY SEPTEMBER. NORMALLY COOLER SPOTS
ACROSS THE NATURE COAST IN CLOSEST PROXIMITY TO THE SURFACE RIDGE
ARE LIKELY TO AGAIN DROP INTO THE UPPER 60S TOWARD DAWN.
MONDAY THROUGH TUESDAY...
UPPER LEVEL RIDGING WILL ESTABLISH ITSELF OVER THE SOUTHEASTERN
CONUS WHILE WEAK TROUGHING / RESIDUAL ENERGY TRIES TO CONSOLIDATE
EAST OF THE FL PENINSULA. OUR REGION WILL REMAIN BETWEEN THESE
FEATURES WITHIN THE SAME ZONE OF WEAK SUBSIDENCE / DRIER AIR ALOFT.
THE LESS THAN FAVORABLE COLUMN FOR DEEP CONVECTION SUGGESTS A
FORECAST FOR LOWER RAIN CHANCES THAN HAS BEEN THE NORM THIS SUMMER
SEASON. THE SURFACE RIDGE TO OUR NORTH WILL BE STRENGTHENING AND
ALLOWING A WELL-DEFINED EASTERLY FLOW TO DEVELOP. THIS EASTERLY FLOW
WOULD NORMALLY BE ASSOCIATED WITH HIGH RAIN CHANCES AS IT FAVORS
CONVECTIVE FOCUS ALONG THE FLORIDA WEST COAST. THE EASTERLY FLOW
SHOULD HELP TO OVERCOME SOME OF THE NEGATIVE FACTORS FOR
CONVECTION...HOWEVER THE DRY AIR WILL BE SIGNIFICANT ENOUGH TO KEEP
POPS WELL BELOW CLIMO NORMS FOR THIS FLOW PATTERN. MONDAY AFTERNOON
RAIN CHANCES WILL SHOW 20% FOR I-4 NORTHWARD AND 30% FURTHER SOUTH.
BY TUESDAY...A SLIGHT MOISTENING BRINGS THE 30% POPS NORTHWARD TO
TAMPA BAY AND MUCH OF THE NATURE COAST. THE STORMS MONDAY AND
TUESDAY SHOULD BE WIDELY SCT IN NATURE AND ALSO BRIEF IN LIFECYLE AS
THEY CONTINUE TO FIGHT THE HOSTILE ENTRAINMENT OF LOW THETA-E AIR.
&&
.LONG TERM (WEDNESDAY THROUGH NEXT SATURDAY)...
WE WILL REMAIN IN DEEP EASTERLY FLOW THROUGH THE EXTENDED PERIOD AS
HIGH PRESSURE HOLDS FIRM TO OUR NORTH. BOTH THE GFS AND THE ECMWF
CARVE OUT A SOMEWHAT DEEPER TROUGH OVER THE NORTHEAST ON
FRIDAY...BUT A NARROW RIDGE OF HIGH PRESSURE SEPARATES FLORIDA FROM
THIS TROUGH.
MOISTURE WILL BEGIN TO RETURN ON WEDNESDAY FOLLOWING A FEW DRIER
THAN NORMAL DAYS. RAIN CHANCES WILL BE CLOSE TO CLIMATIC NORMALS
WITH 30 PERCENT NORTH TO NEAR 50 PERCENT SOUTH.
MODELS AGREE ON A MID-LEVEL DISTURBANCE AND ASSOCIATED SURFACE
TROUGH/TROPICAL WAVE MOVING ACROSS THE STATE WEDNESDAY NIGHT OR
THURSDAY. THE GFS BRINGS PRECIPITABLE WATERS BACK INTO THE 1.9 TO
2.1 INCH RANGE BEHIND THE WAVE THURSDAY AFTERNOON. THIS SHOULD BE
ENOUGH TO BRING RAIN CHANCES BACK UP INTO THE GOOD CHANCE TO LIKELY
CATEGORY...BUT SINCE THE ECMWF IS NOT QUITE AS WET I WILL HOLD RAIN
CHANCES TO ABOUT 50 PERCENT.
FRIDAY AND SATURDAY SHOULD SEE TYPICAL WET-SEASON CONDITIONS WITH
NEAR OR ABOVE-NORMAL RAIN CHANCES EACH AFTERNOON AS EASTERLY FLOW
CLASHES WITH THE SEA BREEZE NEAR THE COAST.
&&
.AVIATION...
VFR CONDITIONS NEXT 24 HOURS. DRIER AIR WILL LIMIT/DELAY
THUNDERSTORM DEVELOPMENT THIS AFTERNOON BUT STILL MAY SEE BRIEF
IMPACTS AROUND PGD...FMY AND RSW.
&&
.MARINE...
A WEAK RIDGE OF HIGH PRESSURE TO THE NORTH OF THE REGION WILL
STRENGTHEN THROUGH THE EARLY PORTION OF THE WEEK...HELPING TO KEEP
AN EASTERLY FLOW PATTERN IN PLACE OVER THE EASTERN GULF OF MEXICO.
THE RIDGE POSITION AND STRENGTH WILL BE SUPPORTIVE OF NOCTURNAL
EASTERLY WIND SURGES MONDAY NIGHT AND TUESDAY NIGHT THAT MAY
APPROACH OR REACH CAUTIONARY LEVELS...ESPECIALLY AWAY FROM THE
COAST.
&&
.FIRE WEATHER...
A WEAK RIDGE OF HIGH PRESSURE TO THE NORTH OF THE FORECAST AREA
TODAY WILL STRENGTHEN THROUGH THE EARLY PORTION OF THE WEEK...
HELPING TO KEEP AN EASTERLY FLOW PATTERN IN PLACE. A DRIER AIRMASS
THAN HAS BEEN EXPERIENCED LATELY IS EXPECTED THE NEXT SEVERAL DAYS
KEEPING RAIN CHANCES DOWN. THE BEST CHANCES TODAY AND MONDAY TO SEE
THE SCATTERED STORMS WILL BE SOUTH OF THE TAMPA BAY AREA. ALTHOUGH
CONDITIONS WILL BE DRIER...NO CRITICALLY LOW RELATIVE HUMIDITY IS
EXPECTED...AND NO SIGNIFICANT FIRE WEATHER CONCERNS ARE IN THE
FORECAST.
FOG POTENTIAL...PATCHY SHALLOW GROUND FOG WILL BE POSSIBLE EACH
MORNING AROUND SUNRISE IN THE NORMALLY FOG PRONE LOCATIONS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 91 74 92 75 / 20 10 20 10
FMY 91 72 92 75 / 50 20 30 20
GIF 92 71 93 73 / 20 10 20 10
SRQ 90 73 93 74 / 30 20 30 20
BKV 92 68 93 70 / 20 10 20 10
SPG 91 78 91 78 / 20 10 20 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS MIAMI FL
157 AM EDT SUN SEP 8 2013
.AVIATION...
MAINLY VFR CONDITIONS ARE EXPECTED FOR ALL SOUTH FLORIDA TERMINALS
DURING THE EARLY MORNING HOURS. HOWEVER...THERE ARE SOME LINGERING
BOUNDARIES ACROSS THE NEAR SHORE ATLANTIC WATERS. THAT IN
COMBINATION WITH PERSISTENT SHOWERS IN THE NEAR SHORE WATERS EAST
OF TERMINALS KFXE AND KFLL COULD ALLOW FOR ADDITIONAL SHOWER AND
ISOLATED THUNDERSTORM DEVELOPMENT THAT COULD AFFECT THE EAST COAST
TERMINALS LATER THIS MORNING...BUT ONLY BRIEF PERIODS OF SUB-VFR
CONDITIONS ARE EXPECTED.
60
&&
.PREV DISCUSSION... /ISSUED 1013 PM EDT SAT SEP 7 2013/
UPDATE...
LATEST SURFACE ANALYSIS SHOWS WEAK CONVERGENCE BOUNDARY ACROSS THE AREA
WHICH WAS THE MAIN FOCUS OF CONVECTION EARLIER MAINLY AROUND THE LAKE
OKEECHOBEE REGION. ACTIVITY HAS STEADILY DECREASED OVER THE PAST FEW
HOURS. 00Z SNDG AND AIRCRAFT DATA SHOW LIGHT LOW LEVEL EASTERLY FLOW
WITH CONSENSUS BETWEEN HRRR AND OTHER HIGH RES LOCAL MODELS BEING BEST
CHANCES OF OVERNIGHT SCATTERED ACTIVITY WILL LIKELY BE ATLANTIC WATERS
DUE TO INTERACTION BETWEEN AFOREMENTIONED BOUNDARY, THE LOW LEVEL FLOW,
AND A LIGHT OFFSHORE DRAINAGE FLOW ALONG THE EAST COAST. THERE IS ALSO
A CHANCE OF SUCH ACTIVITY ACROSS THE GULF WATERS BUT THE CHANCE IS LESS
DUE TO LACK OF OPPOSING LOW LEVEL AND DRAINAGE FLOWS. PRESENCE OF BOUNDARY,
VERY LIGHT LOW LEVEL WINDS, CALM AT THE SURFACE, HIGH ANTECEDENT MOISTURE,
AND DECREASING CLOUDS OVERNIGHT WILL LIKELY RESULT IN PATCHY GROUND
FOG ACROSS PORTIONS OF THE INTERIOR. FORECASTS HAVE ALL BEEN UPDATED
ACCORDINGLY.
PREV DISCUSSION... /ISSUED 746 PM EDT SAT SEP 7 2013/
AVIATION...
OUTSIDE OF SOME LINGERING LIGHT TO MODERATE RAIN WELL INLAND OF
THE TAF SITES THIS EVENING...CONDITIONS REMAIN QUIET WITH VFR
PREVAILING. THIS IS EXPECTED TO PERSIST THROUGH THE NIGHT AND INTO
SUNDAY. SIMILAR TO THIS MORNING...A FEW SHOWERS AND STORMS
SPREADING ASHORE ALONG THE EAST COAST WILL REMAIN POSSIBLE...WHICH
COULD IMPACT THE EAST COAST TERMINALS. THE LOW-LEVEL FLOW UNDER
10 KFT IS FORECAST TO REMAIN LIGHT THROUGH THE DAY SUNDAY...WHICH
WILL MOST LIKELY TRANSLATE TO SLOW MOVING STORMS. AS A
RESULT...WILL INCLUDE VCTS FROM 12Z ON FOR THE EAST COAST SITES
DUE TO THE POTENTIAL MORNING ACTIVITY AND VERY LITTLE STORM MOTION
EXPECTED. THE LATEST MODEL REFLECTIVITIES ARE MAINLY INDICATING
ISOLATED COVERAGE THROUGH SUNDAY.
PREV DISCUSSION... /ISSUED 244 PM EDT SAT SEP 7 2013/
SHORT TERM...
A TROUGH OF LOW PRESSURE OVER CENTRAL FLORIDA WILL CONTINUE TO
MOVE SLOWLY SOUTH TO LAKE OKEECHOBEE BY THIS EVENING...AND REMAIN
NEARLY STATIONARY TONIGHT INTO SUNDAY. THIS WILL KEEP A VERY LIGHT
NORTHEAST STEERING FLOW OVER SOUTH FLORIDA THIS AFTERNOON...BEFORE
GOING CLOSE TO NO STEERING FLOW TONIGHT INTO SUNDAY.
SO THE SHOWERS AND THUNDERSTORMS OVER THE NORTHERN AREAS OF SOUTH
FLORIDA EARLY THIS AFTERNOON WILL DRIFT TO THE SOUTHWEST THROUGH
THE AFTERNOON HOURS BEFORE DISSIPATING THIS EVENING. THESE SHOWERS
AND THUNDERSTORMS WILL ALSO LEAVE AN OUTFLOW BOUNDARY OVER THE
EAST COAST METRO AREAS TONIGHT WHICH COULD HELP TO GENERATE SOME
SHOWERS AND EVEN A FEW STORMS LATE TONIGHT INTO EARLY SUNDAY
MORNING. THEREFORE...THE POPS WILL REMAIN IN THE SCATTERED TO
LIKELY RANGE FOR THIS AFTERNOON OVER THE NORTHERN AREAS TAPERING
DOWN TO LOW END SCATTERED OVER THE SOUTHERN AREAS. THE POPS WILL
THEN DROP TO A SLIGHT 10 PERCENT FOR OVER MOST OF THE AREA FOR
LATE TONIGHT...EXCEPT 20 TO 30 PERCENT OVER THE EAST COAST METRO
AREAS.
WITH NO STEERING FLOW ON SUNDAY OVER SOUTH FLORIDA...THE SHOWERS
AND THUNDERSTORMS WILL MOVE VERY SLOWLY INLAND AS THE WEST AND
EAST COAST SEA BREEZES PUSHES INLAND SLOWLY. SO WILL UP THE POPS
OVER THE AREA FOR SUNDAY TO SCATTERED FOR THE METRO AREAS TO
LIKELY OVER THE INTERIOR AREAS.
THERE COULD ALSO BE SOME FOG OVER THE INTERIOR AND WEST COAST
METRO AREAS LATE TONIGHT AND AGAIN LATE SUNDAY NIGHT...AS THE
WINDS WILL BE CALM ALONG WITH THE LOW LEVEL MOISTURE IN PLACE. SO
WILL ADDED PATCHY FOG FOR THE INTERIOR AND WEST COAST METRO AREAS
FOR LATE TONIGHT AND AGAIN LATE SUNDAY NIGHT.
THE TROUGH OF LOW PRESSURE OVER LAKE OKEECHOBEE WILL THEN WASH OUT
ON MONDAY...AS HIGH PRESSURE STARTS TO BUILD BACK INTO CENTRAL
FLORIDA FROM THE WESTERN ATLANTIC WATERS. THIS WILL ALLOW FOR THE
STEERING FLOW TO BECOME A LITTLE BIT MORE EASTERLY ON MONDAY...AND
ALLOW EAST COAST SEA BREEZE TO PUSH INLAND A LITTLE BIT QUICKER.
SO THE BEST COVERAGE OF SHOWERS AND THUNDERSTORMS ON MONDAY WILL
BE MORE OVER THE INTERIOR AND WEST COAST METRO AREAS.
LONG TERM...
THE RIDGE OF HIGH PRESSURE WILL CONTINUE TO BUILD INTO CENTRAL
FLORIDA MIDDLE TO END OF NEXT WEEK DEEPENING THE EASTERLY WIND FLOW
OVER SOUTH FLORIDA. SO THE BEST AREAS THAT WILL SEE THE SCATTERED
SHOWERS AND THUNDERSTORMS SHOULD BE OVER THE INTERIOR AND WEST
COAST METRO AREAS EACH DAY.
AVIATION...
A WEAK TROUGH HAS ENHANCED THE INSTABILITY OVER SOUTH FLORIDA,
BRINGING NUMEROUS CONVECTIVE SHOWERS AND THUNDERSTORMS. THIS HAS
MADE FOR A TRICKY AVIATION FORECAST. FOR NOW, HAVE KEPT MOST OF
THE ACTIVITY IN THE NORTHERN AREAS, NEAR KPBI AND KFXE, THEN BRING
IT A LITTLE FURTHER SOUTH MID AFTERNOON. ALSO, THE GULF SHOULD
BEGIN TO DEVELOP CONVECTION NEAR KAPF IN THE NEXT COUPLE OF HOURS.
MODELS ARE INDICATING THAT THIS MORNINGS ACTIVITY MAY INHIBIT
CONVECTION FURTHER SOUTH, AT KMIA AND KTMB. SO FOR NOW, JUST HAVE
VCSH AT THOSE SITES. HOWEVER, CONDITIONS COULD CHANGE AND EVEN
THOSE SITES MAY NEED VCTS ADDED THIS AFTERNOON. CONVECTION ALONG
THE ATLANTIC COAST SHOULD MOVE OFF INTO THE INTERIOR PORTIONS,
AWAY FORM THE TAF SITES, AROUND 00Z. TOMORROW COULD SEE ANOTHER
ROUND OF AFTERNOON CONVECTION.
MARINE...
THE WINDS WILL BE NORTHEAST AT 10 KNOTS OR LESS OVER ALL OF THE
LOCAL WATERS OF SOUTH FLORIDA THROUGH MONDAY...BEFORE SWINGING TO
A EASTERLY DIRECTION AND INCREASING TO AROUND 15 KNOTS MIDDLE OF
NEXT WEEK. THIS WILL ALLOW FOR THE SEAS TO REMAIN AT OR BELOW 2
FEET IN BOTH THE ATLANTIC AND GULF WATERS OF SOUTH FLORIDA THROUGH
MONDAY...BEFORE SLOWLY INCREASING TO 2 TO 4 FEET IN THE ATLANTIC
WATERS OF SOUTH FLORIDA BY MIDDLE OF NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 88 75 88 77 / 40 30 30 20
FORT LAUDERDALE 88 77 88 79 / 40 20 30 20
MIAMI 89 76 89 78 / 50 30 40 20
NAPLES 90 73 92 74 / 50 20 40 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...23/SK
AVIATION/RADAR...60/BD
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1253 AM CDT SUN SEP 8 2013
.DISCUSSION...
748 PM CDT
FOR EVENING UPDATE...
HAVE MADE SOME SIGNIFICANT CHANGES TO LOWER POPS/DECREASE COVERAGE
OF SHOWER/THUNDERSTORM CHANCES THIS EVENING AND OVERNIGHT.
CONVECTION HAS STRUGGLED ACROSS THE CWA SINCE LATE THIS
AFTERNOON...LIKELY DUE TO WEAK CONVERGENCE AND RELATIVELY DRY LOW
LEVEL AIR MASS AND PERSISTENT CAP NOTED BETWEEN 800-850MB IN BOTH
ILX/DVN 00Z SOUNDINGS. COLD FRONT REMAINS NORTH/WEST OF THE AREA
AT 01Z...AND WILL SINK ACROSS THE AREA OVERNIGHT...THOUGH
DECREASING DIURNAL INSTABILITY WILL MOST LIKELY LIMIT POTENTIAL
FOR ADDITIONAL SIGNIFICANT SHOWER/THUNDERSTORM DEVELOPMENT
DESPITE HIGH-RES CONVECTIVE ALLOWING GUIDANCE CONTINUING TO
DEPICT POTENTIAL FOR MORE STORMS TO FORM. SPC/RAP MESOANALYSIS
INDICATES STRONGER INSTABILITY/WEAKER CAPPING REMAINS ACROSS
NORTHEAST IA...THUS HAVE MAINTAINED CHANCE POPS MAINLY ACROSS
WEST/SOUTH PARTS OF CWA SIMILAR TO EARLIER THINKING...WHILE
LOWERING TO ISOLATED OR NONE FARTHER EAST/NORTHEAST.
FRONT WILL SLIP IN LATE TONIGHT...WITH INCREASING NORTHEAST WINDS
BY MORNING AS SURFACE HIGH PRESSURE BUILDS SOUTHEAST ACROSS THE
LAKES.
RATZER
//PREV DISCUSSION...
SHORT TERM...TONIGHT THROUGH TUESDAY...
FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO
TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY.
THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER
CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH
FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS
DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST
ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS
ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST
GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING
THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING
COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS
VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN
AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL
MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD
INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING
INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE
POPS MAY BE TOO HIGH.
ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE
TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW
CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW
LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG
ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE
FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST
FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S
NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS
MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT
STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA
DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN
DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT
MAINTAINED A DRY FORECAST FOR NOW.
VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT
AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW
PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW
PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS
A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST
HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL
PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925
MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A
FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR
SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT
OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A
SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY.
GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S
AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR
MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL
BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA
BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL
PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER
CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING
GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD
ONLY IN THE LOW-MID 60S.
LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...
MAINTAINED BLENDED GUIDANCE FOR MID-HIGH CHANCE POPS TUESDAY
EVENING/NIGHT WITH COLD FRONT BUT IF FRONT SLOWS
FURTHER...INSTABILITY MAY WANE ENOUGH TO GREATLY LIMIT COVERAGE OF
SHRA/TSRA. THEN ON WEDNESDAY...THE FRONT WILL STILL BE DROPPING
SOUTHWARD...KEEPING A CHANCE FOR THUNDER GOING. AIR MASS WILL ONLY
BE MODESTLY COOLER INITIALLY. THEN A MUCH COOLER AIRMASS WILL
FINALLY ARRIVE THURSDAY INTO FRIDAY AS EASTERN NOAM TROUGH DEEPENS
AND BRUSHES OUR AREA WHILE STRONG CANADIAN HIGH PRESSURE SPREADS
SOUTHWARD. 850 MB THERMAL TROUGH LOOKS TO ARRIVE THURSDAY NIGHT INTO
FRIDAY...WITH MID TO HIGH SINGLE DIGITS AT 850 MB. SO AFTER A COOLER
BUT BASICALLY SEASONABLE THURSDAY...FRIDAY WILL BE A TASTE OF AUTUMN
WITH HIGHS ONLY IN THE LOW-MID 70S AWAY FROM LAKE MICHIGAN AND
MID-UPPER 60S ON THE LAKEFRONT. HEIGHT RISES WILL QUICKLY RETURN
SATURDAY SO TEMPERATURES WILL WARM SLIGHTLY.
RC
&&
.CLIMATE...
653 PM CDT
RECORD WARMTH FOR SEPTEMBER 10TH IS POSSIBLE ON TUESDAY:
CHICAGO:
RECORD HIGH: 95 (1983)
RECORD WARM LOW: 75 (1912)
ROCKFORD:
RECORD HIGH: 96 (1931)
RECORD WARM LOW: 70 (2000)
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* NNE WINDS TURNING NE THROUGH THE MORNING. GUSTS INTO THE TEENS
OVERNIGHT AND TO NEAR 20 KT AT TIMES DURING THE DAY.
* LOW END MVFR CIGS ARRIVING NEXT 1-2 HOURS AND MAY PERSIST
THROUGH THE MORNING. BRIEF IFR POSSIBLE.
MDB
//DISCUSSION...UPDATED 06Z...
COLD FRONT NOW MAKING IT THROUGH RFD AND GYY WITH WINDS TURNING
NORTH TO NORTHEAST BEHIND IT. AN INCREASE IN SPEEDS LAGS BEHIND
THE FRONT BUT UPSTREAM SITES IN WISCONSIN HAVE BEEN SEEING SOME
GUSTS INTO THE 15 TO 20 KT RANGE AND EXPECT THAT SOME GUSTINESS
WILL ARRIVE LOCALLY IN THE NEXT 1-2 HRS. GUSTS TO 20 KT LOOK MORE
LIKELY DURING THE DAY. SATELLITE SHOWS LOW END MVFR STRATUS...WITH
SOME EMBEDDED IFR...MOVING SOUTHWARD TOWARD THE TERMINALS AND HAVE
ADJUSTED TIMING OF ARRIVAL OF BKN MVFR CIGS AT THE TERMINALS. THE
MAIN CHALLENGE WILL BE TIMING THE SCATTERING/EXITING OF MVFR CIGS
TODAY. COVERAGE IS PRETTY EXTENSIVE FROM SOUTHEAST WI
NORTHEASTWARD INTO NORTHERN LOWER MICHIGAN. HAVE RETAINED THE 18Z
TIME FOR SCATTERING AS THIS LOOKS REASONABLE AND STRATUS MAY BEGIN
TO EXPAND WITH TIME OVERNIGHT FURTHER SUPPORTING A SLOW
IMPROVEMENT. IT DOES APPEAR THAT VFR WILL RETURN THIS AFTERNOON.
HIGH PRESSURE WILL PASS TO THE EAST OF THE AREA TONIGHT WHICH WILL
ALLOW WINDS TO SHIFT SOUTHEASTERLY THIS EVENING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN WIND TRENDS.
* HIGH CONFIDENCE IN LOW END MVFR ARRIVING NEXT FEW HOURS...MEDIUM
CONFIDENCE IN HOW QUICKLY IT WILL SCATTER/DEPART.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY THROUGH TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE.
THURSDAY THROUGH FRIDAY...VFR.
RATZER
&&
.MARINE...
129 PM CDT
A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF
LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE
LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE
NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO
25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A
DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING
SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS
CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR
THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL
CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL
BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES
ARE EXPECTED.
THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST
SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER
GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A
CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS
SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE
EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF
ON EXTENDING THE ADVISORY INTO THIS PERIOD.
THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL
LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW
PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA.
LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP
ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM SUNDAY TO 11 PM
SUNDAY.
IN...BEACH HAZARDS STATEMENT...INZ001...4 AM SUNDAY TO 11 PM SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM
SUNDAY.
SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11
PM SUNDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS DES MOINES IA
335 AM CDT SUN SEP 8 2013
.SHORT TERM.../TODAY /...
ISSUED AT 334 AM CDT SUN SEP 8 2013
THE COLD FRONT HAS PUSHED THROUGH ALL BUT THE FAR SOUTHEAST CORNER
OF IOWA WITH LIGHT NLY WIND OVER THE CWA. WINDS WILL VEER TO NELY
AND EVENTUALLY ELY. LOWERED TEMPS A BIT WITH THE STRONGER PUSH OF
COOLER AIR AND THE PROSPECT FOR MORE CLOUDINESS. AREAS OF CONCERN
ARE THREE FOLD TODAY. FIRST IS THE STRATUS DECK ENTERING NERN IA
THIS MORNING AND HOW FAR IT WILL PUSH TO THE SOUTHWEST. THINKING IS
THAT IT WILL PUSH ABOUT A THIRD OF THE WAY ACROSS THE STATE BEFORE
IT STARTS TO BREAK UP. TEMPS MAY WELL STRUGGLE TO MAKE 80 IN THE
FAR NERN PART OF THE CWA. SECOND CONCERN IS WITH THE MCS OVER THE
DAKOTAS. SPILL OFF CLOUDINESS MAY WELL HAVE A SIGNIFICANT IMPACT ON
TEMPS. THOUGH WE ARE STARTING OUT QUITE WARM...IT WOULD SEEM THAT
FEW PLACES WILL BREAK OUT OF THE 80S...AND THAT WILL BE IN THE FAR
SOUTHWEST. THIRD CONCERN IS THE HRRR DEVELOPMENT OF SHOWER ACTIVITY
OVER WESTERN IA THIS MORNING. DON`T SEE A LOT OF SUPPORT FOR THAT
EVEN GIVEN SOME AC AND VIRGA DEVELOPMENT OVER EASTERN NEBRASKA AT
PRESENT. THERE IS MORE SUPPORT THERE AND IT IS STRUGGLING WITH THE
EML IN PLACE. WITH THAT SAID...WILL GO A TOUGH ABOVE MOS GUIDANCE
FOR HIGHS TODAY. LEFT POPS OUT EXCEPT FOR THE POTENTIAL OF SOME
EARLY MORNING TSRA OVER THE EXTREME SOUTHEAST AS THESE HAVE HAD A
TENDENCY TO BACK DEVELOP THROUGH THE EARLY MORNING HOURS.
.LONG TERM.../TONIGHT THROUGH FRIDAY/...
ISSUED AT 334 AM CDT SUN SEP 8 2013
STRONG WARM ADVECTION WILL PASS THROUGH CENTRAL IOWA LATE TONIGHT
AND THROUGH THE DAY ON MONDAY AS LOW PRESSURE MOVES THROUGH THE
DAKOTAS AND INTO MINNESOTA. A WELL MIXED PROFILE WILL BE IN PLACE
BY THE AFTERNOON FUELED BY BREEZY SOUTHWEST WINDS. DEWPOINTS WILL
DROP INTO THE 50S TO LOWER 60S AS THE PROFILES MIX IN THE
AFTERNOON. HIGH TEMPERATURES WILL JUMP INTO THE MID 90S TO
POSSIBLY LOW 100S BY MID AFTERNOON. THESE READINGS ARE NEAR TO
ABOVE RECORD VALUES. THE CURRENT LATEST 100 DEGREE DAY AT DES
MOINES OCCURRED ON SEPTEMBER 7TH 1939 THEREFORE IF THE FORECAST OF
100 VERIFIES...IT WILL ECLIPSE THAT MARK. BOTH WATERLOO (SEPTEMBER
15TH 1927) AND OTTUMWA (SEPTEMBER 11TH 1936) HAVE HAD 100 DEGREE
DAYS BEYOND THIS POINT.
A FRONTAL BOUNDARY WILL GRADUALLY SAG THROUGH IOWA MONDAY NIGHT
THROUGH TUESDAY NIGHT AS THE AREA OF LOW PRESSURE SHIFTS TO THE
EAST. THE BOUNDARY WILL BE QUITE SLOW TO MOVE SOUTH AS THE UPPER
LEVEL RIDGE STUBBORNLY GIVES WAY TO A SHORT WAVE MOVING EAST ALONG
THE US/CANADIAN BORDER. THE PRIMARY ENERGY WITH THIS SYSTEM WILL
BE PASSING TO THE NORTH OF THE STATE NEAR THE UPPER WAVE AND IN
THE VICINITY OF THE RIGHT REAR QUAD OF THE UPPER JET. THE MAIN
POTENTIAL FOR PRECIPITATION WILL BE POST SFC FRONTAL AND CLOSER TO
THE 850 MB BOUNDARY LATE TUESDAY INTO TUESDAY NIGHT. CONFIDENCE IS
NOT HIGH THAT ANY BENEFICIAL RAIN WILL OCCUR WITH THIS SYSTEM AND
ESPECIALLY IN THE EXPANDING D2 DROUGHT REGION OVER THE CENTRAL AND
WEST CENTRAL AREAS. A TRANSITION TO NORTHWEST FLOW TUESDAY NIGHT
AND WEDNESDAY WILL FINALLY PUSH THE BOUNDARY SOUTH OF THE STATE
AND THIS WILL ALLOW A LARGE CANADIAN HIGH PRESSURE SYSTEM TO DROP
INTO THE UPPER MIDWEST AND WESTERN GREAT LAKES REGION FOR THE END
OF THE WEEK. THE HIGH WILL BRING A REFRESHING BLAST OF COOLER AIR
WITH HIGHS IN THE 70S BY FRIDAY AND OVERNIGHT LOWS POSSIBLE
DROPPING INTO 40S OVER THE NORTH.
&&
.AVIATION...08/06Z
ISSUED AT 1152 PM CDT SAT SEP 7 2013
WINDS WILL SHIFT FROM THE NORTH TO THE EAST BEHIND BOUNDARY. WITH
LIGHTER WINDS ACROSS THE NORTH AND CLEAR SKIES THROUGH MUCH OF THE
OVERNIGHT ANTICIPATE AREAS OF BR TO AFFECT NORTHERN TAF SITES
KFOD/KMCW/KALO/KDSM NEAR 12Z...WITH IFR CONDITIONS POSSIBLE. BR
WILL QUICKLY LIFT AS WINDS INCREASE AFTER 12Z. MAY SEE GUSTS IN
THE AFTERNOON. WINDS WILL BECOME MORE SOUTHERLY LATE IN THE PERIOD.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MS SEP 2013
LONG TERM...DONAVON
AVIATION...AWB
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
323 AM CDT SUN SEP 8 2013
.SYNOPSIS...
ISSUED AT 315 AM CDT SUN SEP 8 2013
06Z SFC ANALYSIS HAS A WEAK LOW NORTHEAST OF KOTM WITH A FRONT
PASSING NORTH OF THE QUAD CITIES AND EAST INTO NORTHERN INDIANA. A
COLD FRONT RAN FROM THE LOW SOUTHWEST TO THE NE/KS LINE. AN
INVERTED TROF RAN FROM THE LOW INTO SOUTHEAST MINNESOTA WHILE
ANOTHER TROF RAN SOUTHEAST FROM THE LOW INTO CENTRAL ILLINOIS. DEW
POINTS WERE IN THE 60S ACROSS THE MIDWEST WITH POCKETS OF 70
AROUND THE LOW AND COLD FRONT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT SUN SEP 8 2013
THE CONCERNS ARE THE CONVECTION IN THE SOUTHERN CWFA AND THE
APPROACHING LOW CLOUDS FROM WISCONSIN.
THE CONVECTION AROUND KGBG AND NOW IMMEDIATELY WEST OF THERE IS
CONTINUOUSLY FORMING AND MOVING OVER THE SAME AREAS. THE CULPRIT
IS A COMBINATION OF CONVERGENCE AROUND THE TROF OVER THAT AREA.
PER THE RAP TRENDS THIS IS EXPECTED TO CONTINUE FOR THE NEXT
SEVERAL HOURS BEFORE WEAKENING. THUS SOME ISOLATED AREAS WILL SEE
LOCALLY HEAVY RAINFALL THROUGH SUNRISE.
THE RAP IS DOING A RESPECTABLE JOB OF DEPICTING THE LOW CLOUDS
APPROACHING FROM WISCONSIN AND WILL ENTER THE NORTHERN CWFA PRIOR
TO SUNRISE.
FOR TODAY...THE CONVECTION IN THE SOUTHERN CWFA SHOULD DISSIPATE
AFTER SUNRISE WHILE LOW CLOUDS CONTINUE TO OVERSPREAD ACROSS THE
NORTHEAST THIRD TO 40 PERCENT OF THE CWFA. THE FRONT WILL SLOWLY
SAG SOUTH AND IS EXPECTED TO CLEAR THE CWFA DURING THE AFTERNOON.
DIURNAL HEATING IS EXPECTED TO ALLOW VERY ISOLATED SHOWERS AND
THUNDERSTORMS TO DEVELOP DURING THE AFTERNOON IN THE SOUTHERN CWFA
WHERE CONVECTIVE TEMPERATURES SHOULD BE ACHIEVED IN SPITE OF THE
WARM AIR ALOFT.
TONIGHT...MAINLY QUIET AND DRY CONDITIONS ARE EXPECTED AS THE FRONT
BEGINS MOVING BACK NORTH AS A WARM FRONT. ..08..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 315 AM CDT SUN SEP 8 2013
TEMPERATURES WILL BE THE MAIN CONCERN MONDAY AND TUESDAY AS VERY
WARM AIR SURGES NORTHEAST BEHIND A WARM FRONT MOVING THROUGH THE
FORECAST AREA BY EARLY MONDAY AFTERNOON. H8 TEMPS ARE FORECAST TO
INCREASE INTO THE LOW TO MID 20/S IN THE WARM SECTOR BY MONDAY
AFTERNOON. MIXING THESE TEMPERATURES TO THE SURFACE YIELDS MAX
TEMPS IN THE MID TO UPPER 90S WHICH LOOKS REASONABLE FOR THE
SOUTHWEST 2/3RDS. WITH THE WARM FRONT MOVING OUT OF THE NORTHEAST
COUNTIES DURING THE AFTERNOON...HIGHS WERE KEPT IN THE LOW 90S.
DEWPOINTS SHOULD BE IN THE MID OR UPPER 60S MONDAY WHICH WILL BE
HIGH ENOUGH TO PRODUCE HEAT INDEX VALUES AROUND 100 DURING THE
AFTERNOON. BY TUESDAY A COLD FRONT WILL BE JUST NORTHWEST OF THE
AREA AT 12Z AND WILL MOVE SLOWLY SOUTH REACHING THE SOUTHEASTERN
COUNTIES BY LATE AFTERNOON. AREAS ALONG AND SOUTH OF HIGHWAY 30
WILL HAVE PLENTY OF TIME TO HEAT UP AND SHOULD SEE ANOTHER DAY OF
MID 90 TEMPERATURES. TO THE NORTH WITH THE FRONT MOVING THROUGH
EARLY IN THE DAY...HIGHS SHOULD BE AROUND 90. SOUTHWEST WINDS AHEAD
OF THE FRONT ARE PROGGED TO TAP DRIER AIR OVER THE
PLAINS...KEEPING DEWPOINTS LOWER THAN THOSE EXPECTED ON MONDAY.
THE DRIER AIR WILL KEEP HEAT INDEX VALUES UNDER 100. HIGHS IN THE
90S MONDAY AND TUESDAY WILL BE CLOSE TO RECORD HIGHS FOR THE 9TH
AND 10TH OF SEPTEMBER. MONDAYS RECORDS ARE AROUND 100 AND SHOULD
BE JUST OUT OF REACH BUT SLIGHTLY COOLER RECORDS FOR TUESDAY WILL
BE ATTAINABLE ESPECIALLY AT MOLINE AND BURLINGTON. SEE THE CLIMATE
SECTION BELOW FOR MONDAY/S AND TUESDAY/S RECORD HIGHS AND DATE OF
THE LAST OCCURRENCE.
THE RAIN THREAT WILL BE NIL THROUGH EARLY TUESDAY AFTERNOON. THEN
JUST A SLIGHT CHANCE NORTH PRIOR TO 00Z WEDNESDAY. THE WARM SECTOR
SHOULD BE CAPPED...AND AS STATED ABOVE DEWPOINTS WILL BE DRYING
OUT SOME AHEAD OF THE FRONT. THE BEST POTENTIAL FOR RAIN WILL BE
POST FRONTAL WHERE LOW LEVEL MOISTURE WILL BE POOLING AND THE MID
LEVEL CAP STARTS TO ERODE. MODELS WERE ALSO SHOWING SOME DEEP
LAYER FGEN IN THE ENTRANCE REGION OF A H3 80KT JET STREAK OVER MN
AND WI WHICH SHOULD CONTRIBUTE TO THE POST FRONTAL FORCING.
DESPITE THESE SIGNALS FAVORING RAIN...THERE IS STILL A WIDE RANGE
OF QPF FORECASTS AMONG THE MODELS WITH THE LATEST ECM RUN DRY FOR
NEARLY ALL OF THE CWFA. WITH THE MODELS STILL LENDING A LOT OF
UNCERTAINTY TO THE PRECIP FORECAST FOR TUESDAY NIGHT AND WEDNESDAY...
HAVE KEPT THE POPS IN THE CHANCE CATEGORY.
THE FRONT WILL BE SOUTH OF THE AREA BY TUESDAY EVENING ENDING ANY
RAIN THREAT FOR THE REST OF THE WEEK. HIGH PRESSURE SLIDING
SOUTHEAST THROUGH THE GREAT LAKES BY LATE WEEK WILL BRING COOL DRY
AIR TO THE REGION. BY FRIDAY AND SATURDAY WE SHOULD SEE HIGHS IN
THE 70S OVER THE ENTIRE AREA WITH LOWS IN THE 40S AND 50S BY
SATURDAY MORNING.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1124 PM CDT SUN SEP 8 2013
A DRY COLD FRONTAL PASSAGE IS OCCURRING OVER EASTERN IOWA AS OF 04Z
TONIGHT...AND ONLY A FEW ISOLATED SHOWERS ARE NOW EXPECTED IN FAR
SOUTHEAST IOWA AND WEST CENTRAL ILLINOIS THROUGH 09Z/08.
OTHERWISE...ATTENTION IS TURNING TOWARD A HIGH LIKELIHOOD OF
STRATUS AND POSSIBLE MVFR FOG TOWARD MORNING. SURFACE WINDS AND
WINDS ALOFT WILL BECOME EASTERLY...PULLING IN COOLER AIR OFF LAKE
MICHIGAN. THIS SHOULD CREATE A WIDESPREAD STRATUS FIELD OVER ALL
OF EASTERN IOWA AND NORTHERN ILLINOIS. THIS STRATUS SHOULD HAVE
CIGS OF 800 FT TO 2000 FT...AND MAY LINGER THROUGH AT LEAST 18Z/08
BEFORE LIFTING AND SCATTERING OUT. ERVIN
&&
.CLIMATE...
ISSUED AT 113 AM CDT SUN SEP 8 2013
RECORD HIGHS FOR SEPTEMBER 9...
MOLINE.........99 IN 1933
CEDAR RAPIDS...98 IN 1955
DUBUQUE........97 IN 1955
BURLINGTON.....100 IN 1912
RECORD HIGHS FOR SEPTEMBER 10...
MOLINE.........95 IN 1983
CEDAR RAPIDS...98 IN 1931
DUBUQUE........97 IN 1895
BURLINGTON.....97 IN 1933
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...08
SHORT TERM...08
LONG TERM...DLF
AVIATION...ERVIN
CLIMATE...DLF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
201 AM EDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 201 AM EDT SUN SEP 8 2013
SOME ISENTROPIC LIFT DEVELOPING OUT AHEAD THE OHIO VALLEY COLD FRONT
HAS ALLOWED FOR SOME ISOLATED SHOWERS TO MOVE IN FROM THE NORTHWEST.
HAVE UPDATED TO INCLUDE THIS MENTION...ALTHOUGH DO NOT FORESEE THESE
GETTING SOUTH OF AN IRVINE TO JACKSON TO PIKEVILLE LINE. FRESHENED UP
THE HOURLY TEMPERATURES...DEW POINTS...AND SKY COVER AS WELL.
UPDATE ISSUED AT 740 PM EDT SAT SEP 7 2013
BASED ON THE LATEST HRRR AND 18Z NAM...HAVE BACKED OFF ON POPS LATE
TONIGHT WITH VERY LITTLE CHANCE OF SEEING MUCH ACTIVITY UNTIL AFTER
12Z. IN FACT...CEILINGS TO THE NORTH ARE STILL 12KFT OR HIGHER WITH
VERY LITTLE EVIDENCE OF CEILINGS COMING DOWN. MOISTURE APPEARS VERY
LIMITED IN THE LOWER LEVELS AND GIVEN THE LACK OF INSTABILITY...HARD
TO SEE MUCH SHOWER ACTIVITY DEVELOPING OVERNIGHT. ALSO SPED UP THE
TEMPERATURE DROP OFF THIS EVENING AS CLEAR SKIES SHOULD ALLOW FOR A
QUICK DROP IN TEMPERATURES THIS EVENING...WITH SOME OF THE VALLEYS
POSSIBLY SINKING INTO THE 50S BY LATE EVENING PRIOR TO THE ARRIVAL OF
THE MID/HIGH CLOUDS FROM THE NORTH. CLOUDS SHOULD EVENTUALLY SLOW
DOWN THE TEMPERATURE FALL FOR THE SECOND HALF OF THE
NIGHT...ESPECIALLY IN THE NORTH. CLOUDS WILL EVENTUALLY REACH THE
TENNESSEE BORDER BY 09Z. ZFP UPDATE WILL BE OUT SOON...BUT NDFD GRIDS
HAVE ALREADY BEEN SENT.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 245 PM EDT SAT SEP 7 2013
18Z SFC ANALYSIS SHOWS RETREATING HIGH PRESSURE THROUGH EAST KENTUCKY
MAKING FOR A VERY PLEASANT...WARM...AND MOSTLY SUNNY DAY.
TEMPERATURES HAVE GENERALLY CLIMBED INTO THE LOWER 80S ON THEIR WAY
TO THE MID 80S. MEANWHILE...DEWPOINTS ACROSS THE AREA ARE HOLDING IN
THE LOWER 60S FOR MOST OF THE AREA...MID 60S NEAR THE TENNESSEE
BORDER...UPPER 50S NORTH OF INTERSTATE 64.
THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM PART OF
THE FORECAST WITH A LARGE RIDGE TO THE IMMEDIATE WEST OF THE AREA AND
TROUGHING TO THE NORTHEAST. BETWEEN THESE...A COUPLE OF SHORTWAVES
WILL PASS OVER THE OHIO VALLEY THROUGH SUNDAY NIGHT. ONE OF THESE...
PASSES BY JUST TO THE EAST ON SUNDAY AND WILL BRIEFLY BUCKLE THE
WESTERN RIDGE THROUGH MIDDAY SUNDAY. GIVEN THE MODEL AGREEMENT...HAVE
FOLLOWED THE HIGHER RESOLUTION NAM12 FOR WX SPECIFICS.
SENSIBLE WEATHER WILL FEATURE A MILD NIGHT WITH HIGHER DEWPOINTS AND
MORE CLOUDS KEEPING THE VALLEYS FROM DROPPING OFF AS MUCH AS LAST
NIGHT. LIKEWISE...EXPECT THE FOG TO BE LESS PREVALENT IN THE ALL BUT
THE DEEPER VALLEYS BY MORNING. THE APPROACHING COLD FRONT WILL BRING
A THREAT OF SHOWERS OR THUNDERSTORMS TO NORTHERN PARTS OF EAST
KENTUCKY BY DAWN. THE FRONT DROPS THROUGH THE CWA DURING THE DAY
SUNDAY AND COMBINED WITH PEAK HEATING WILL BRING A BETTER CHANCE OF
SHOWERS AND THUNDERSTORMS TO THE ENTIRE AREA. RIDGING BUILDS BACK IN
ALOFT BY EVENING...THOUGH...AS THE MID LEVEL SHORTWAVE PASSES AND
THIS SHOULD PUT AN END TO THE CONVECTION THREAT SHORTLY AFTER 00Z.
ANOTHER MILD NIGHT FOLLOWS WITH PATCHY VALLEY FOG ANTICIPATED BY
DAWN.
USED THE CONSSHORT AND ITS BC BROTHER TO JUMP START THE TD AND WIND
GRIDS THROUGH 12Z SUNDAY...CONSALL THEREAFTER. FOR TEMPERATURES...
USED THE OBS DATABASE AS A BASIS FOR THE DIURNAL CURVE AND MODIFIED
CONSALL MAX AND MIN TEMPS...NOT TOO MUCH TERRAIN ADJUSTMENT AT NIGHT
GIVEN THE BUILDING CLOUDS TONIGHT AND FRONTAL CLOUDS SUNDAY NIGHT. AS
FOR POPS...ENDED UP MOST SIMILAR TO THE MET NUMBERS THROUGH THE SHORT
TERM PERIOD.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 245 PM EDT SAT SEP 7 2013
STILL DECENT AGREEMENT AMONGST THE EXTENDED MODELS FOR DAYS 3 THRU 7
OF THE FORECAST. HIGH PRESSURE WILL BE THE DOMINANT FEATURE ON
MONDAY...WITH PARTLY CLOUDY SKIES AND DRY CONDITIONS EXPECTED. A
SERIES OF WEAK WEATHER SYSTEM WILL BRING ISOLATED TO SCATTERED
SHOWERS AND STORMS TO THE AREA AS THEY MOVE ACROSS THE EASTERN THIRD
OF THE CONUS TUESDAY THROUGH THURSDAY. THE BEST CHANCE OF RAIN WILL
LIKELY OCCUR ON THURSDAY AS A SLUGGISH FRONTAL BOUNDARY INTERACTS
WITH THE TERRAIN OF EASTERN KENTUCKY. TEMPERATURES WILL TOP OUT
MOSTLY IN THE MID TO UPPER 80S THROUGH THURSDAY. HIGHS ON FRIDAY AND
SATURDAY WILL BE MUCH COOLER BEHIND THE DEPARTING FRONT...WITH HIGHS
TOPPING OUT MOSTLY IN THE MID TO UPPER 70S EACH DAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 201 AM EDT SUN SEP 8 2013
AN APPROACHING COLD FRONT WILL BRING MOSTLY CLOUDY SKIES AS WELL AS A
FEW ISOLATED SHOWERS THROUGH THE DAWN. IFR OR WORSE FOG WILL ALSO BE
SEEN...MAINLY ALONG THE DEEPER RIVER VALLEYS...ALTHOUGH LOZ HAS
ALREADY DROPPED DOWN TO IFR BRIEFLY. EXPECT IFR CONDITIONS AT LOZ
THROUGH AROUND 09Z BEFORE THE THICKENING CLOUDS ALLOW FOR SOME
IMPROVEMENT BETWEEN 09 AND 12Z. WILL KEEP IT VFR AT JKL AND SME WITH
SME HAVING A LOWER CROSSOVER TEMPERATURE FROM YESTERDAY AFTERNOON AND
JKL BEING A RIDGETOP. ISOLATED CONVECTION WILL THREATEN DURING THE
AFTERNOON ACROSS EASTERN KENTUCKY AS THE COLD FRONT WEAKENS AND MOVES
THROUGH THE AREA...HOWEVER WILL CONTINUE TO HOLD OFF ON ANY MENTION
IN THE TAFS FOR NOW...GIVEN THE LIMITED AREAL COVERAGE EXPECTED.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...GREIF
LONG TERM...AR
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
535 AM EDT SUN SEP 8 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 520 AM EDT SUN SEP 8 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE OVER NW CANADA AND
A TROF OVER ERN NAMERICA. STRONG SHORTWAVE DIVING SE TOWARD NEW
ENGLAND HAS RESULTED IN AMPLIFICATION OF THE ERN TROF OVER THE LAST
24HRS. UPSTREAM...MID LEVEL LOW THAT HAS BEEN OVER THE PACIFIC NW
OVER THE LAST FEW DAYS HAS MOVED LITTLE. CENTER IS CURRENTLY OVER
FAR NE WA. DOWNSTREAM OF THIS FEATURE...TAP OF SUBTROPICAL MOISTURE
EXTENDING INTO THE NRN ROCKIES HAS BEEN AIDING CLUSTERS OF SHRA/TSRA
ACROSS WY/MT INTO THE DAKOTAS. CLOSER TO HOME...IN THE WAKE OF THE
SHORTWAVE MOVING TOWARD NEW ENGLAND...SFC HIGH PRES HAS SETTLED OVER
NRN ONTARIO. FEED OF DRIER AIR ASSOCIATED WITH THE HIGH RESULTED IN
LOW CLOUDS/FOG ACROSS PORTIONS OF UPPER MI CLEARING OUT LAST
EVENING. EARLY THIS MORNING...ONLY SOME THIN CI BLOWOFF FROM
CONVECTION WELL TO THE W IS SPILLING INTO THE UPPER LAKES.
FCST AREA TODAY WILL BE UNDER THE INFLUENCE OF HIGH PRES MOVING SE
FROM NORTHERN ONTARIO. CU RULE SUGGESTS SCT CU SHOULD DEVELOP FOR A
TIME THIS MORNING/EARLY AFTN...SIMILAR TO WHAT WAS OBSERVED N/NW OF
LAKE SUPERIOR YESTERDAY. OTHERWISE...WILL PROBABLY CONTINUE TO SEE
SOME MAINLY THIN CI ACROSS THE FCST AREA TODAY. TEMPS WILL BE ON THE
COOL SIDE OF NORMAL DESPITE SUNSHINE. MIXING TO THE INVERSION BASE
ON FCST SOUNDINGS YIELDS HIGH TEMPS NEAR 70 AWAY FROM THE MODERATING
INFLUENCE OF THE GREAT LAKES. THIS LINES UP WELL WITH OBSERVED HIGHS
UPSTREAM YESTERDAY.
TONIGHT...MIDLEVEL LOW CURRENTLY OVER NE WA WILL BEGIN TO OPEN UP
AND DRIFT E INTO MT. WHILE THIS FEATURE WILL STILL BE TOO FAR W TO
BE A FACTOR HERE...MODELS SHOW WEAKER SHORTWAVES LIFTING NE AHEAD OF
THE LOW AND AROUND WEAKENING CNTRL CONUS RIDGE. AS IN RECENT DAYS...
FCST DILEMMA IS WHETHER ANY OF THESE WEAKER SHORTWAVES WILL BE ABLE
TO SPREAD PCPN INTO THE FCST AREA TONIGHT. THE ECMWF CONTINUES TO BE
MOST AGGRESSIVE SPREADING PCPN INTO THE UPPER LAKES. IN FACT...THE
00Z RUN IS MOST AGGRESSIVE AS IT SPREADS PCPN ACROSS THE ENTIRE FCST
AREA TONIGHT. MEANWHILE...OTHER MODELS WHICH HAD SUPPORTED A FASTER
EWD PUSH OF PCPN (UKMET IN PARTICULAR) HAVE BACKED OFF. GIVEN THE
RATHER SHARP ERN TROF...BELIEVE THE ECMWF IS PROBABLY TOO FAST
DRIVING PCPN EWD. 03Z SREF PROBABILITY OF AT LEAST 0.01 INCH OF PCPN
TONIGHT ONLY REACHES AROUND 20PCT OVER THE FAR W. SINCE BULK OF
GUIDANCE PAINTS A SIMILAR PICTURE TO THE SREF...WILL BASICALLY
MAINTAIN FCST CONTINUITY WITH THE LAST SEVERAL FCSTS AND ONLY BRING
SCHC POPS INTO THE W OVERNIGHT. OTHERWISE...SOUTHERLY RETURN FLOW OF
WARMER/MOISTER AIR AND AN INCREASE IN CLOUDS WILL RESULT IN A WARMER
NIGHT MOST AREAS...ESPECIALLY OVER THE W WHERE GRADIENT WILL BE
TIGHTENING FIRST AND WHERE THICKER CLOUDS WILL ARRIVE EARLIEST.
LINGERING DRY AIR MASS IN THE EVENING COMBINED WITH INITIALLY MOSTLY
CLEAR SKIES AND LIGHT WIND OVER THE E MAY ALLOW TEMPS AT TRADITIONAL
INTERIOR COLD SPOTS TO FALL INTO THE LWR 40S. ONE SIDE ISSUE THAT
MAY ARISE TONIGHT IS THE POTENTIAL FOR LOW CLOUDS AND/OR FOG OVER
THE E. IF SOUTHERLY WINDS UP LAKE MICHIGAN INCREASE SUFFICIENTLY...
LOW CLOUDS AND/OR FOG WILL DEVELOP AS HIGHER DWPT AIR OFF THE LAKE
ADVECTS INTO THE CHILLY INTERIOR. WILL BE SOMETHING TO WATCH FOR.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 535 AM EDT SUN SEP 8 2013
AT 12Z MONDAY UPPER MI WILL BE UNDER THE INFLUENCE OF THE 500MB
RIDGE...STRETCHING ACROSS MUCH OF THE S CENTRAL AND SE U.S. OUR EYES
WILL BE ON THE 500MB TROUGH OVER MT/ID/WY...WHICH WILL SUPPRESS THE
RIDGE TO OUR S AS THE TROUGH PUSHES TOWARD THE UPPER GREAT LAKES.
WARM FRONT WILL SURGE TO OUR N MONDAY MORNING...BEING THE FOCUS OF
SHRA/TSRA DURING THE DAY. THERE REMAINS SOME SIGNIFICANT
DISCREPANCIES ON THE TIMING WHEN COMPARING AVAILABLE MODELS. WHILE
THE NAM/GFS/CANADIAN MODELS KEEP BASICALLY ALL OF THE LAND
/EXCLUDING THE KEWEENAW PENINSULA/ DRY ON MONDAY...THE GENERALLY
FAVORED ECMWF HAS A SOLID 0.25IN OR MORE OVER THE ENTIRE LAND. HAVE
CONTINUED TO UTILIZE A MODEL CONSENSUS APPROACH...WHICH LEADS TO
AROUND 0.5 TO 1IN OF QPF FROM LATE TONIGHT THROUGH TUESDAY OVER THE
KEWEENAW PENINSULA...AND E AREAS N OF A LINE FROM MUNISING THROUGH
NEWBERRY. EXPECT MUCH OF THE STRONGER STORMS TO FOLLOW THE COLD
FRONT FARTHER TO OUR S...WITH LIGHTNING AND HEAVY RAIN BEING THE
MAIN THREATS FOR OUR CWA. AS FOR NON-PRECIP TALK...THE WAA WILL
RESULT IN A WARM NIGHT MONDAY NIGHT...APPROX 15F ABOVE NORMAL FOR
THIS TIME OF YEAR. THIS WILL BE THANKS TO WARM S WINDS REAMING UP
THROUGH THE NIGHT.
IT LOOKS TO BE A VERY ACTIVE AT 500MB FROM TUESDAY MORNING THROUGH
THE END OF THE WORK WEEK. THE INITIAL KICKER OF A SHORTWAVE WILL
PUSH W TO E ACROSS THE CWA TUESDAY AS THE SFC LOW EXITS E LAKE
SUPERIOR INTO SE QUEBEC. THIS WILL TIME OUT WITH THE RIGHT REAR
QUADRANT OF THE 250MB JET.
ALTHOUGH NOT A THREAT OF THUNDERSTORMS WILL BE DONE AFTER TUESDAY
AFTERNOON...THE EXTENDED SECTION OF THE FCST IS NOT WITHOUT
SIGNIFICANCE. LOOK FOR THE NEXT 500MB TROUGH TO SWING THROUGH MID
WEEK. WHILE NOT A SIGNIFICANT RAIN MAKER...IT WILL MARK THE START OF
SIGNIFICANTLY COOLER WEATHER. NW TO N WINDS WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT...WITH LINGERING LOW LEVEL MOISTURE. KEPT SLIGHT
CHANCE-CHANCE POPS NEAR LAKE SUPERIOR AS 850MB TEMPS FALL TO AROUND
-2C BY DAYBREAK FRIDAY. HIGHS IN THE 60S...AND EVEN UPPER 50S LOOK
REASONABLE FOR BOTH THURSDAY AND FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 136 AM EDT SUN SEP 8 2013
WITH HIGH PRESSURE BUILDING INTO THE REGION...VFR CONDITIONS WILL
CONTINUE TO PREVAIL AT KIWD/KCMX/KSAW THROUGH THE FORECAST PERIOD
WITH LIGHT EASTERLY WINDS. HOWEVER...THERE MAY BE BRIEF VIS
FLUCTUATIONS OVERNIGHT AT KIWD DUE TO PATCHES OF SHALLOW RADIATIONAL
FOG. WITH SOME CI SPREADING ACROSS THE AREA...DO NOT THINK THE FOG
WILL DEEPEN AND BECOME A PREVAILING CONDITION.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 535 AM EDT SUN SEP 8 2013
HIGH PRES OVER NRN ONTARIO WILL DRIFT SE TODAY. JUST AHEAD OF THE
HIGH...EXPECT A BRIEF PUSH OF STRONGER WINDS (GUSTS TO 20-25KT) OVER
MUCH OF LAKE SUPERIOR EARLY THIS MORNING. COASTAL CONVERGENCE OVER
FAR WRN LAKE SUPERIOR AND PERHAPS BTWN THE HURON ISLANDS AND THE
KEWEENAW MAY STILL LEAD TO SOME GUSTS OVER 20KT LOCALLY THRU THE
AFTN. OTHERWISE...WINDS WILL SETTLE DOWN A BIT FOR THE AFTN...
ESPECIALLY OVER THE E...CLOSER TO SFC HIGH PRES CENTER. AS THE HIGH
MOVES AWAY FROM THE UPPER LAKES TONIGHT...GRADIENT SHOULD REMAIN
WEAK ENOUGH TO KEEP WINDS UNDER 20KT.
ANOTHER PERIOD OF STRONGER WINDS WILL BE POSSIBLE THURSDAY INTO
THURSDAY EVENING...WITH N-NW GUSTS OF 25-30KTS OVER MAINLY CENTRAL AND E
LAKE SUPERIOR...AS STRONG HIGH PRESSURE NEARS FROM S CENTRAL
CANADA AND LOW PRESSURE EXITS ACROSS QUEBEC.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...KF
AVIATION...JLB
MARINE...KF
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1113 PM CDT SAT SEP 7 2013
.SYNOPSIS...
ISSUED AT 319 PM CDT SAT SEP 7 2013
H5 ANALYSIS THIS MORNING HAS LOW PRESSURE CENTERED OVER
EASTERN WASHINGTON STATE WITH HIGH PRESSURE OVER NWRN KS. RIDGING
EXTENDED NORTH OF THIS HIGH INTO THE DAKOTAS. TROUGHING CONTINUED
ACROSS EASTERN CANADA INTO NEW ENGLAND. AT THE SURFACE...A WEAK COOL
FRONT HAS PUSHED INTO WESTERN AND NORTH CENTRAL NEBRASKA AND WAS
POSITIONED ROUGHLY ALONG INTERSTATE 80 FROM LINCOLN TO NORTH PLATTE.
THIS FRONTAL BOUNDARY HAS BEEN ENHANCED BY DECAYING CONVECTION AND
HAS ACTUALLY BEEN PUSHED FARTHER SOUTH THAN THE MODELS INDICATED
YESTERDAY. TEMPERATURES AS OF 3 PM CDT RANGED FROM THE UPPER 80S IN
THE NORTHEASTERN CWA...TO AROUND 100 IN THE SOUTHWEST.
&&
.UPDATE...
ISSUED AT 1005 PM CDT SAT SEP 7 2013
POPS HAVE BEEN REMOVED FOR THE OVERNIGHT FORECAST. THERE IS WAY
TOO MUCH DRY AIR IN THE MID LEVELS TO SUPPORT STORM DEVELOPMENT
AND EVEN THE HRRR HAS GONE SILENT DEVELOPING ANY CONVECTION. THE MCS ACROSS
SD PROBABLY WILL NOT AFFECT THE FCST AREA OVERNIGHT SO IT LOOKS
LIKE A DRY FORECAST OVERNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 319 PM CDT SAT SEP 7 2013
MODELS INDICATE A WEAK DISTURBANCE TOPPING THE CENTRAL
PLAINS RIDGE LATER THIS EVENING ALLOWING FOR A ISOLATED MENTION OF
STORM DEVELOPMENT. THE MOST LIKELY SCENARIO INVOLVES STORMS FIRING
OFF THE HIGHER TERRAIN OF EASTERN WYOMING/WESTERN SOUTH DAKOTA LATE
THIS AFTERNOON...THEN DRIFTING SOUTHEAST OVERNIGHT ACROSS NORTH
CENTRAL NEBRASKA AND PORTIONS OF THE NORTHERN SANDHILLS. THUS WILL
MAINTAIN A SLIGHT CHANCE MENTION IN THIS AREA FOR NOW. ANOTHER
ABNORMALLY HOT DAY IS IN STORE FOR SUNDAY ACROSS MUCH OF WESTERN
NEBRASKA. HIGH TEMPERATURES WILL TOP IN THE MID 90S TO NEAR THE
CENTURY MARK FOR MOST LOCATIONS SAVE NORTH CENTRAL NEBRASKA WHERE A
GREATER SOUTHEASTERLY COMPONENT TO THE LOWER TROPOSPHERIC FLOW WILL
USHER IN SLIGHTLY COOLER TEMPERATURES. OTHERWISE PRECIPITATION
CHANCES WILL BE LIMITED TO FAR NORTHWESTERN PORTIONS OF THE CWA LATE
SUNDAY AS THE UPPER RIDGE AXIS SHIFTS SLIGHTLY TO THE EAST AND A
TROUGH DEEPENS OVER THE NORTHERN ROCKIES. A COLD FRONT WILL DROP
SOUTH THROUGH THE DAKOTAS AND APPROACH NW NEBRASKA BY LATE
AFTERNOON. THIS FRONT SHOULD PROVIDE A FOCUS FOR STORM DEVELOPMENT
WEST AND NORTH OF THE CWA BUT REMAIN REMOVED FROM THE FORECAST AREA.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 319 PM CDT SAT SEP 7 2013
SUNDAY NIGHT THROUGH TUESDAY...THE MAIN FORECASTING
CHALLENGE IS COLD FRONTAL TIMING MONDAY AFTERNOON/EVENING AND
ASSOCIATED PRECIPITATION CHANCES. ON SUNDAY NIGHT...A SEMISTATIONARY
FRONT WILL SLOWLY TRACK FROM THE WESTERN NEBRASKA PANHANDLE...INTO
THE EASTERN NEBRASKA PANHANDLE. TSRAS WILL CONTINUE INVOF OF THE
FRONT SUNDAY EVENING AND ARE NOT EXPECTED TO PERSIST INTO THE
OVERNIGHT HRS...AS THE BEST UPPER LEVEL SUPPORT CONTINUES OVER THE
WESTERN DAKOTAS AND NERN WYOMING. ON MONDAY...AN UPPER LEVEL TROUGH
OF LOW PRESSURE WILL MIGRATE ACROSS SRN SASKATCHEWAN...FORCING THE
COLD FRONT THROUGH THE FORECAST AREA BY LATE MONDAY AFTERNOON. THE
NAM AND GFS HAVE COME IN SLIGHTLY FASTER WITH THE FRONTAL TIMING TDY
COMPARED TO YESTERDAY...AND TRENDED MAX TEMPS DOWNWARD FROM THE
INHERITED FCST. LOW PRECIPITATION CHANCES WILL ACCOMPANY THE FRONTAL
PASSAGE...HOWEVER...HIGHER POPS ARE EXPECTED INTO MONDAY
EVENING...AS MID LEVEL FRONTOGENESIS INCREASES ACROSS THE SANDHILLS
INTO NORTHEASTERN PORTIONS OF THE FORECAST AREA. THIS MID LEVEL
FRONTOGENESIS WILL SHIFT SLOWLY SOUTH INTO SOUTHWESTERN NEBRASKA
OVERNIGHT INTO TUESDAY MORNING WITH THE CORRIDOR OF HIGHEST POPS
SHIFTING ACCORDINGLY.
TUESDAY NIGHT THROUGH SATURDAY...THE FRONTAL BOUNDARY WILL DROP
SOUTH INTO KANSAS STALLING ACROSS CENTRAL OR NORTHERN KANSAS TUESDAY
NIGHT INTO WEDNESDAY. AS WAS THE CASE YESTERDAY...LOCATION OF THE
FRONT...STILL IN SOME DOUBT WITH THE GFS FURTHER SOUTH WITH THIS
FEATURE COMPARED TO THE LATEST 12Z ECMWF. REGARDLESS OF MODEL
CHOICE...DECIDED TO CONFINE POPS TO THE SRN THIRD OF THE FORECAST
AREA WEDNESDAY AND WEDNESDAY NIGHT. BY THURSDAY...THE FRONT...WILL
SHIFT NORTH AS A WARM FRONT AS HIGH AMPLITUDE RIDGING BUILDS INTO
THE CENTRAL CONUS. PRECIPITATION CHANCES WILL SHIFT NORTH ALONG THE
FRONT THURSDAY INTO FRIDAY WITH DRY CONDS EXPECTED FRIDAY NIGHT INTO
SATURDAY. TEMPERATURES ON WEDNESDAY AND THURSDAY...WILL BE IN THE
UPPER 70S TO AROUND 80...WITH HIGHS REBOUNDING BACK INTO THE 80S FOR
FRIDAY AND SATURDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1111 PM CDT SAT SEP 7 2013
VERY DRY AIR APPEARS TO BE IN PLACE ACROSS THE FCST AREA IN THE
MID LEVELS OF THE ATM. THUNDERSTORM ACTIVITY SHOULD REMAIN ACROSS
SD OVERNIGHT BUT THERE IS AN OUTSIDE CHANCE A STORM OR TWO COULD
BUILD INTO NRN NEB TONIGHT. OTHER ISOLATED STORMS COULD DEVELOP
AFTER 21Z SUNDAY ACROSS NWRN NEB. OTHERWISE VFR IS EXPECTED
THROUGHOUT THE FCST AREA.
&&
.FIRE WEATHER...
ISSUED AT 321 PM CDT SAT SEP 7 2013
MODEL GUIDANCE CONTINUE TO INDICATE MINIMUM RELATIVE HUMIDITY OF 20
PERCENT OR LESS SUNDAY AFTERNOON FOR FIRE ZONES
210...219...SOUTHERN/CENTRAL HALF OF ZONE 204...AND WESTERN PORTIONS
OF ZONE 206. TEMPERATURES THERE WILL RISE ONCE AGAIN TO NEAR 100
DEGREES WITH DEW POINTS FALLING INTO THE UPPER 40 TO LOW 50 DEGREE
RANGE. WINDS WILL BE STRONG AND FROM THE SOUTH WITH GUST POTENTIAL
OF 25 MPH OR GREATER ACROSS MUCH OF WESTERN NEBRASKA TOMORROW
AFTERNOON. FUELS MAY BE A LIMITING FACTOR HOWEVER AS THEY CONTINUE
TO CURE. SOME FIRE SPREAD IS POSSIBLE BUT WIDESPREAD LARGE/EXTREME
GROWTH IS NOT ANTICIPATED YET.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CDC
SYNOPSIS...CLB
SHORT TERM...JACOBS
LONG TERM...CLB
AVIATION...CDC
FIRE WEATHER...JACOBS
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
411 AM CDT SUN SEP 8 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 409 AM CDT SUN SEP 8 2013
COMPLEX OF STORMS ACROSS NORTH CENTRAL SOUTH DAKOTA IS EXPECTED TO
SHIFT EAST THIS MORNING AND MAY SCRAPE THE NORTHERN EDGE OF THE
FORECAST AREA THIS MORNING. APPEARS AS THOUGH STORMS ARE DEVELOPING
BEHIND THE LEADING EDGE OF WARM AIR/THETA-E ADVECTION IN A MORE
UNSTABLE ENVIRONMENT. HI RES MODELS HANDLING THE SHORT TERM
RELATIVELY POORLY...WITH MOTH THE RAP AND THE HRRR SUGGESTING THE
ACTIVITY WOULD REMAIN WELL TO THE NORTH NEAR THE NORTH DAKOTA
BORDER. IN GENERAL...WIND SHEAR APPEARS TO BE FAIRLY WEAK SO AM NOT
ANTICIPATING SEVERE WEATHER THROUGH THE MORNING WITH THIS ACTIVITY
AS IT WORKS EAST.
INCREASING SOUTHERLY FLOW ACROSS THE AREA TODAY WILL LEAD TO ANOTHER
WARM AND HUMID DAY ACROSS THE REGION. HAVE TRIMMED BACK FORECAST
HIGHS IN THE NORTH WITH EXPECTED CONVECTION AND CLOUD COVER LIMITING
HEATING POTENTIAL SOME. WITH 925 HPA WINDS INCREASING TO NEAR 20
KNOTS...SHOULD SEE GUSTY WINDS OF 15-20 KNOTS.
EXPECT WIND GUSTS TO DROP OFF THROUGH THE EVENING...BUT SHOULD BE A
FAIRLY WARM NIGHT ACROSS THE REGION WITH SUSTAINED WINDS REMAINING
IN THE 10-15 KNOT RANGE. MODELS SUGGEST A SECONDARY WARM FRONT WILL
LIFT THROUGH THE REGION AND MAY BECOME THE FOCUSING MECHANISM FOR
ELEVATED STORMS ACROSS SOUTHWEST MINNESOTA AND ADJACENT AREAS. WENT
AHEAD AND INCREASED POPS FOR THIS AREA...WITH THE POTENTIAL FOR A
FEW STORMS TO BE MARGINALLY SEVERE WITH STRONGLY VEERING WIND SHEAR
PROFILES.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 409 AM CDT SUN SEP 8 2013
THE COLD FRONT WILL WORK ITS WAY ACROSS THE CWA MONDAY AFTERNOON
INTO THE OVERNIGHT HOURS. LOOKS LIKE GOOD HEATING POTENTIAL AHEAD OF
THE FRONT...WITH A SOUTHWESTERLY BREEZE GUSTING TO AROUND 30 MPH AND
COMPRESSIONAL HEATING. GIVEN OUR LACK OF GOOD MIXING RECENTLY...WAS
HESITANT TO GO TOO WARM WITH HIGHS...SO WHILE I DID GO HIGHER THAN
THE COOL BIAS CORRECTED VALUES...DID NOT GO WITH FULL MIXING TO 850
MB. FRONTAL TIMING IS STILL A BIT UNCERTAIN...AND THIS WILL HAVE AN
IMPACT ON HIGHS AS WELL. HIGHEST READINGS SHOULD BE ACROSS NORTHWEST
IOWA AND PORTIONS OF SOUTHWEST MINNESOTA...WHERE MID AND A FEW UPPER
90S SEEM PROBABLE. THE MARSHALL TO SIOUX FALLS TO YANKTON CORRIDOR
HAS THE HIGHER UNCERTAINTY...HOWEVER MOST MODEL SOLUTIONS KEEP THE
FRONT SLOW ENOUGH TO ALLOW THESE AREAS TO WARM INTO THE LOW TO MID
90S. CURRENTLY LOOKS LIKE HEAT INDICES WILL BE IN THE MID TO UPPER
90S...BUT SHOULD REMAIN BELOW 100...WITH THE INCREASED MIXING ALSO
HELPING TO LOWER DEWPOINTS SOME AHEAD OF THE FRONT.
LOOKING AT TWO POTENTIAL CHANCES FOR PRECIPITATION WITH THE FRONTAL
PASSAGE. THE PRE FRONTAL ATMOSPHERE SHOULD GENERALLY REMAIN CAPPED
THROUGH THE DAY. HOWEVER...RIGHT ALONG AND JUST BEHIND THE
FRONT...INDICATIONS THAT MOISTURE POOLING WILL RESULT IN AN INCREASE
IN DEWPOINTS. IT IS POSSIBLE THAT THIS...COMBINED WITH
FRONTOGENETICAL FORCING WILL BE ENOUGH TO BREAK THE CAP. IF THIS
HAPPENS IT WOULD LIKELY BE IN THE 21Z TO 03Z TIMEFRAME....GENERALLY
ALONG AND NORTHWEST OF A YANKTON TO WORTHINGTON LINE. THIS IMMEDIATE
POST FRONTAL ATMOSPHERE SHOULD BE CHARACTERIZED BY CAPE AROUND 1500
J/KG AND EFFECTIVE DEEP LAYER SHEAR OF ABOUT 30 KTS. SO WHILE
NOTHING TOO IMPRESSIVE...THESE PARAMETERS ARE ENOUGH TO SUGGEST AN
ISOLATED SEVERE STORM WOULD BE POSSIBLE. THE SECOND THREAT WILL BE
AS THE MAIN UPPER WAVE PASSES TO OUR NORTH. WHILE THE BEST PV
ADVECTION WILL REMAIN NORTH...A 60 TO 80 KT UPPER JET PASSING TO OUR
NORTH WILL PUT US IN FAVORED THE RIGHT ENTRANCE REGION. WHILE THIS
UPPER LEVEL SUPPORT APPEARS TOO LATE TO HELP WITH THE NEAR SURFACED
BASED CONVECTION POTENTIAL DISCUSSED ABOVE...IT MAY INTERACT WITH
THE 700 MB FRONT AND ALLOW FOR THE DEVELOPMENT OF ADDITIONAL SHOWER
AND THUNDERSTORMS FROM ABOUT 06Z ON. BY THIS TIME...MID LEVEL LAPSE
RATES BECOME PRETTY WEAK...AND THUS ELEVATED INSTABILITY WILL BE
LOW. MAYBE ENOUGH TO GET THUNDER...BUT WOULD NOT EXPECT ANYTHING
SEVERE WITH THIS ACTIVITY. WITH PWATS RUNNING 2 TO 3 STANDARD
DEVIATIONS ABOVE NORMAL...AND STORM MOTIONS NEARLY PARALLEL TO THE
MID LEVEL FRONT...LOCALLY HEAVY RAIN WOULD BE POSSIBLE. WILL JUST
KEEP HIGH CHANCE POPS FOR NOW...AS THE OVERNIGHT ACTIVITY WILL
PROBABLY BE PRETTY NARROW AND FOCUSED CLOSE TO THE 700 MB
FRONT...AND UNCERTAINTY EXISTS ON WHERE EXACTLY THIS WILL SET UP.
ALSO SOME MODEL RUNS ARE PRETTY WEAK ON QPF...POSSIBLY DUE TO THE
WEAK INSTABILITY AND A BIT OF A DRY LAYER AROUND 850 MB...SO WHILE
IT LOOKS LIKE A GOOD CHANCE MONDAY NIGHT...WILL CONTINUE TO HOLD OFF
ON LIKELY POPS FOR THE TIME BEING.
MODELS TRENDING TOWARDS STALLING THE FRONT FURTHER SOUTH THAN
PREVIOUSLY THOUGHT. THIS WILL PROBABLY LIMIT THE PRECIP POTENTIAL
TUESDAY INTO TUESDAY NIGHT...BUT WILL KEEP A SMALL POP GOING ACROSS
NORTHWEST IOWA. WE WILL SEE COOLER TEMPERATURES FILTER IN BEHIND THE
FRONT TUESDAY INTO WEDNESDAY AS THE RIDGE FLATTENS. ALTHOUGH STILL
EXPECTING ABOVE NORMAL READINGS IN THE LOW TO MID 80S. DEWPOINTS MAY
LINGER IN THE LOW 60S TUESDAY...BUT SHOULD FINALLY DROP INTO THE 50S
BY WEDNESDAY...BRINGING AN END TO THE HUMID PERIOD. A STRONG WAVE
MOVING ACROSS SOUTHERN CANADA WILL HELP PUSH A A BACKDOOR COLD FRONT
AND EVEN COOLER AND LESS HUMID CONDITIONS INTO THE REGION THURSDAY
INTO FRIDAY. EXPECTING HIGHS IN THE 70S BOTH DAYS...WITH ONLY AREAS
NEAR THE MISSOURI RIVER POTENTIALLY HITTING 80. ALSO WOULD EXPECT
COOLER NIGHTTIME TEMPERATURES WITH HIGH PRESSURE CENTERED TO OUR
NORTHEAST. FRIDAY MORNING CURRENTLY LOOKS TO BE THE
COOLEST...POSSIBLY BEING THE FIRST NIGHT IN A WHILE WHERE LOWS
ACTUALLY END UP BELOW NORMAL...IN THE UPPER 40S TO MID 50S. AS THE
RIDGE BEGINS TO BUILD BACK IN LATER FRIDAY INTO SATURDAY...THE
THUNDERSTORM THREAT SHOULD AGAIN BEGIN TO INCREASE OVER THE REGION.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1040 PM CDT SAT SEP 7 2013
MVFR TO IFR FOG IS EXPECTED TO INCREASE SLOWLY THROUGH 12Z FROM
AREAS TO WIDESPREAD OVER NORTHWEST IOWA AND EXTREME SOUTHEAST SD.
VISIBILITIES BELOW 3SM WILL LIKELY BECOME FREQUENT WITH AREAS OF
CEILINGS BELOW 1K FEET. MORE PATCHY 3-5SM IN LIGHT FOG WILL
DEVELOP FURTHER NORTHWEST. 14Z-17Z FOG AND LOW CEILINGS WILL
DECREASE WITH HEATING AND CONDITIONS WILL BECOME VFR OVER THE
AREA. VFR CONDITIONS WILL THEN CONTINUE THROUGH 09/06Z.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...CHENARD
AVIATION...
SEE BELOW FOR AN UPDATED AVIATION FORECAST DISCUSSION.
THE SEVERE THUNDERSTORM WATCH WAS EXPIRED AT 05Z. OVERALL FORECAST
IS IN FAIR SHAPE AND DONT EXPECT TO MAKE ANY MAJOR CHANGES. SMALL
COMPLEX OF STORMS OVER NORTHWEST SOUTH DAKOTA HAS HELD TOGETHER ON
THE DEVELOPING NOCTURNAL LLJ. EAST OF THE MO RVR REMAINS A
TOUGHER CALL AND REALLY AM NOT SURE IF THE AGGRESSIVE HRRR MODEL
IS CORRECT. FOR NOW WILL STICK WITH SLIGHT CHC POPS EAST OF THE MO
RVR AS LLJ IS NOT EXPECTED TO MIGRATE MUCH IF ANY EAST TNT.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...THROUGH TUESDAY AM
A FEW WEAK...ELEVATED SHOWERS PASSING THROUGH THE CWA THIS
PM...MAINLY ACROSS THE NORTHERN TIER ALL THANKS TO A SHORTWAVE
MOVING THROUGH NORTH DAKOTA. ATMOSPHERE OVER THE CWA IS MARGINALLY
UNSTABLE...SO WILL LEAVE IN LOW POPS...AGAIN FOR THE NORTHERN
TIER. FOCUS SHIFTS WEST...WITH ANOTHER WEAK WAVE LIFTING OUT OF
WYOMING. A 20-25KT LOW LEVEL JET WILL DEVELOP IN RESPONSE TO THIS
FEATURE...WITH THE FOCUS IN FAR NORTHWEST SOUTH DAKOTA/WESTERN
NORTH DAKOTA. WILL CONTINUE LOW POPS FOR FAR NORTHWEST COUNTIES IN
CASE ANYTHING ELEVATED MANAGES TO TRICKLE INTO THE CWA. A LEE
LOW/INVERTED TROF FORMS OVER CENTRAL SOUTH DAKOTA ON SUNDAY. VERY
WARM MID LEVEL AIR...WITH H7 TEMPERATURES UPWARDS OF +15C MOVES
INTO CENTRAL SOUTH DAKOTA...THOUGH TEMPERATURES ACROSS THE
NORTHERN AND WESTERN PERIPHERY OF THE CWA ARE COOLER. STEEP LAPSE
RATES AND WIND SHEAR ABOVE THE MIXED LAYER SUGGEST THE POTENTIAL
FOR SEVERE STORMS...THE MAIN QUESTION BEING HOW FAR NORTH AND WEST
DOES THE ELEVATED MIXED LAYER EFFECTIVELY CAP CONVECTION...AND
JUST HOW FAR UNDER THAT CAP WILL THE SURFACE BOUNDARY SET UP. AT
THIS POINT...THINKING IS THE CAP WILL HOLD...AND ANY CONVECTION
THAT FIRES WILL EITHER BE ELEVATED OR VERY SHORT LIVED. BETTER
CHANCES ARE EXPECTED AS THE SHORTWAVE GETS CLOSER TO THE CWA AND A
NEARLY 50KT LOW LEVEL JET SET UP OVER THE CWA. STORMS WOULD LIKELY
FORM ALONG THE NORTHERN PERIPHERY OF THE CWA WHERE JET CONVERGENCE
IS GREATEST...WITH AN EAST/NORTHEAST MOTION. THE SURFACE FRONT
WILL TAKE THROUGH MOST OF MONDAY TO EXIT THE CWA...WITH WEAK COLD
ADVECTION AND GOOD MIXING IN ITS WAKE...EXPECT TEMPERATURES TO
JUMP ABOVE NORMAL AGAIN FOR HIGHS MONDAY. ADVECTION IS NEUTRAL SO
TEMPERATURES TUESDAY ABOUT THE SAME AS MONDAY.
.LONG TERM...TUESDAY THROUGH SATURDAY
MOST OF THE EXTENDED PERIOD LOOKS TO BE QUIET UNTIL THE FRIDAY AND
SATURDAY TIME FRAME. TUESDAY STARTS OFF WITH NORTHWEST FLOW ALOFT
AND DRY CONDITIONS AS THERE IS A LACK OF EMBEDDED WAVES IN THE
UPPER LEVELS. SFC HIGH PRESSURE THEN BEGINS BUILDING SOUTH INTO
THE AREA BY THURSDAY...BRINGING COOLER TEMPERATURES. AFTER HIGHS
IN THE 80S TUESDAY AND WEDNESDAY...HIGHS SHOULD SLIP BACK INTO THE
70S FOR THURSDAY. MODELS THEN SHOW SHORTWAVE ENERGY MOVING INTO
THE WESTERN DAKOTAS ON FRIDAY...WITH THE WAVE TRACKING ACROSS THE
REST OF THE DAKOTAS FRIDAY NIGHT INTO SATURDAY MORNING. A SFC COLD
FRONT SHOULD THEN MOVE EAST ACROSS THE AREA AT SOME POINT SATURDAY
INTO SATURDAY EVENING. ALL THIS LEADS TO CHANCES FOR SHOWERS AND
STORMS...INITIALLY ACROSS WESTERN AND CENTRAL SOUTH DAKOTA
FRIDAY...THEN FOR THE REMAINDER OF THE AREA FRIDAY NIGHT AND
SATURDAY.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
A COMPLEX OF THUNDERSTORMS IS WORKING INTO THE KMBG TERMINAL.
EXPECT SUB-VFR VISBIES IN HEAVY RAIN AND STRONG WINDS.
ELSEWHERE...IF THIS CLUSTER OF STORMS CAN KEEP IT TOGETHER THROUGH
09Z...THE KABR TERMINAL WOULD BE NEXT TO POTENTIALLY RECEIVE SOME
SUB-VFR FLYING WEATHER CONDITIONS IN THUNDER.
AT THIS POINT...KPIR AND KATY MAY JUST GET BY WITHOUT A
THUNDERSTORM THIS MORNING...AT LEAST PRIOR TO 12Z. WIDESPREAD
MID/HIGH CLOUDS MAY PRECLUDE ANY MVFR GROUND FOG FROM GETTING
GOING ACROSS THE REGION. BUT...WILL LEAVE IT IN FOR NOW AND ADJUST
IN THE NEXT FEW HOURS.
ANOTHER ROUND OF THUNDERSTORMS IS POSSIBLE LATER SUNDAY EVENING
AND ON INTO THE OVERNIGHT HOURS. THE KMBG AND KABR TERMINALS STAND
THE LARGEST PROBABILITY OF RECEIVING SOME OF THIS POTENTIAL
CONVECTION.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...DORN
SHORT TERM...CONNELLY
LONG TERM...TMT
AVIATION...DORN
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1140 PM CDT SAT SEP 7 2013
.UPDATE...AREA RADARS SHOWED SOME ISOLATED TO SCATTERED SHOWERS
DROPPING SOUTHWARD ACROSS SOUTHERN ILLINOIS LATE TONIGHT, AND
LATEST HRRR SUGGESTS THAT AT LEAST ISOLATED SHOWERS OR
THUNDERSTORMS COULD MAKE IT DOWN INTO NORTHEASTERN MIDDLE
TENNESSEE TOWARD SUNRISE, AS WEAK COLD FRONT DROPS SOUTHWARD.
THESE ISOLATED SHOWERS AND STORMS MAY VERY WELL PERSIST DURING THE
LATER MORNING HOURS OVER EASTERN AREAS. THUS, HAVE ADDED THE
POSSIBILITY OF ISOLATED SHOWERS AND STORMS TO EASTERN AREAS AFTER 12Z.
HAVE ALSO RAISED DEW POINTS AND MIN TEMP EXPECTATIONS A BIT, BASED
ON LATEST TRENDS AND MOS GUIDANCE.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
19
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
406 AM MDT SUN SEP 8 2013
.SHORT TERM...THE STUBBORN UPPER LEVEL RIDGE WILL FINALLY BEGIN TO
SHIFT EASTWARD AS AN UPPER LEVEL TROUGH MOVES INTO THE NRN
ROCKIES BY TONIGHT. INFLUX OF SUBTROPICAL MOISTURE WILL REMAIN IN
THE MTNS AND ACROSS THE NRN FOOTHILLS THRU TONIGHT WITH SCT TSTMS
DEVELOPING BY AFTN. ELSEWHERE OUTFLOW BOUNDARIES FM CONVECTION
OVER THE HIGHER TERRAIN MAY SWEEP ACROSS THE FRONT RANGE BY LATE
AFTN INTO THE EARLY EVENING HOURS ALLOWING FOR SOME ISOLD TO WDLY
SCT HIGHER BASED STORMS TO DVLP. AS FOR HIGHS ONE MORE AFTN FOR 90
DEGREE PLUS READINGS OVER NERN CO. RECORD AT DENVER IS 94 DEGREES
WHICH COULD BE TIED OR BKN DEPENDING ON TIMING OF MID LVL CLOUD
COVER THIS AFTN.
FOR TONIGHT EXPECT SOME LINGERING SHOWERS AND A FEW STORMS IN THE
MTNS OVERNIGHT AS SUBTROPICAL MOISTURE FEED CONTINUES. OVER NERN CO
ISOLD-WDLY SCT TSTM ACTIVITY ALONG THE FRONT RANGE SHOULD END BEFORE
06Z. BY LATE TONIGHT A COOL FRONT WILL BEGIN TO MOVE SOUTH INTO
NERN CO WITH NLY WINDS DEVELOPING TOWARDS SUNRISE.
.LONG TERM...MODELS CONTINUE TO SHOW A SHIFT IN THE UPPER FLOW
PATTERN THAT WILL BRING A FEW DAYS OF RAINFALL TO PARTS OF NORTH-
CENTRAL AND NORTHEAST COLORADO. THE UPPER RIDGE THAT DOMINATED
COLORADO WEATHER THIS PAST WEEK WITH RECORD BREAKING TEMPERATURES
WILL CONTINUE MOVING EASTWARD AND WEAKENING FOR THE NEXT 48-60
HOURS AS AN UPPER TROUGH MOVES OVER THE NORTHERN ROCKIES AND TO
THE CANADIAN PRARIES. OVER COLORADO...THE FLOW OF MID-LEVEL
SUBTROPICAL MOISTURE IS EXPECTED TO STRENGTHEN. THIS WILL LEAD TO
AN INCREASE IN SHOWER ACTIVITY OVER THE MOUNTAINS WHICH WILL ALSO
EXTEND ONTO THE NORTHEAST COLORADO PLAINS. TUESDAY LOOKS LIKE IT
IS GOING TO BE THE COOLEST DAY OF THE WEEK DUE TO A SURGE OF COOL
AIR COMING INTO THE STATE FROM THE NORTH MONDAY NIGHT. THE AIRMASS
MAY ALSO BE COOLED SOME BY THE RAINFALL FROM MONDAY NIGHT. SHOWER
ACTIVITY MONDAY EVENING IS GOING TO BE ENHANCED BY A WEAK UPPER
LEVEL JET ASSOCIATED WITH THE NORTHERN ROCKIES TROUGH THAT WILL
BE IN PLACE OVER WYOMING. EACH OF THE MODELS INDICATE THAT SHOWERS
OVER THE FORECAST AREA COULD LAST THROUGH MOST OF MONDAY NIGHT.
ONCE THE UPPER LEVEL PATTERN SHIFTS TO MOIST AND SOUTH-
SOUTHWESTERLY ON MONDAY...IT WILL REMAIN IN PLACE MOST OF THE
WEEK. SHOWERS ARE EXPECTED TO KEEP GENERATING EACH DAY AS
SUBTROPICAL MOISTURE CONTINUES MOVING INTO THE STATE. AT THIS TIME
IT IS DIFFICULT TO TELL IF ANY OF THE DAYS WILL HAVE PARTICULARLY
HEAVY RAINFALL...SO WILL JUST KEEP AN EYE ON THE MODEL RUNS AS
THEY KEEP COMING IN. MODEL SOUNDINGS SHOW THAT PRECIPITABLE WATER
VALUES WILL INITIALLY RISE TO THE 1.00 TO 1.10 INCH RANGE WHICH IS
NOT THAT ABNORMAL FOR THE LATE SUMMER. THE FORECAST PACKAGE DID
NOT NEED THAT MUCH ADJUSTMENT THIS TIME AROUND.
&&
.AVIATION...DRAINAGE WINDS EARLY THIS MORNING MAY BECOME LIGHT AND
VARIABLE BY 14Z AND LINGER THRU 18Z. BY EARLY AFTN WINDS WILL
BECOME MORE SSE. LAST FEW RUNS OF THE RAP SHOWS A RATHER STG
OUTFLOW BNDRY COMING OUT OF THE FOOTHILLS AND ACROSS DIA IN THE
00Z-01Z TIME PERIOD ALONG WITH SOME ISOLD HIGHER BASED STORMS SO
WILL MENTION VCTS WITH A TEMPO GROUP FOR GUSTY OUTFLOW WINDS FOR A
FEW HOURS. AFTER CONVECTIVE BOUNDARIES MOVE ACROSS WINDS SHOULD
GRADUALLY SHIFT BACK TO MORE SSW BY 06Z. OVERNIGHT LOOKS LIKE A
A SHIFT TO NLY WINDS WILL OCCUR IN THE 12Z-15Z TIMEFRAME ON MON AS
A COOL FRONT MOVE ACROSS. AT THIS TIME NO LOW CLOUDS ARE EXPECTED
WITH THIS FEATURE.
&&
.HYDROLOGY...WILL SEE SCATTERED STORMS IN THE MTNS AND NRN
FOOTHILLS THIS AFTN ALTHOUGH THE FLOW ALOFT WILL BE A BIT STRONGER
SO THEY SHOULD MOVE ALONG. RAINFALL AMOUNTS WILL BE LESS THAN ONE
HALF INCH HOWEVER UP TO AN INCH COULD OCCUR WITH ANY STRONGER
STORM.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....DANKERS
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
355 AM MDT SUN SEP 8 2013
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 353 AM MDT SUN SEP 8 2013
PATTERN SHIFT UNDERWAY ACROSS THE WESTERN U.S. AS THE CLOSED LOW
OVER THE PACNW FINALLY KICKS EAST. THIS WILL ALLOW THE DEEP
MONSOONAL PLUME THAT HAS BEEN PARKED JUST TO OUR WEST...TO SHIFT
EAST AND SOUTH OVER OUR AREA FOR THE NEXT FEW DAYS. SEVERAL
EMBEDDED WAVES WITHIN THE FLOW WILL ENHANCE CONVECTION AND TEAM
WITH THE NUMEROUS OUTFLOW BOUNDARIES ROAMING THE FORECAST AREA TO
TRIGGER AN INCREASE IN CONVECTION THIS AFTERNOON. POTENTIAL FOR
HEAVY RAIN DEFINITELY ON THE INCREASE WITH MODEL PRECIPITABLE
WATER FORECAST JUMPING TO OVER AN INCH THIS AFTERNOON AND PEAK
AROUND 1.40 INCHES BY EARLY MONDAY MORNING. EXPECT ENOUGH BREAKS
IN CLOUD COVER TODAY TO ALLOW A FEW STRONGER STORMS TO FIRE WITH
THE HRRR DEVELOPING DEEPER CONVECTION AFTER 18Z ACROSS SOUTHEAST
UTAH. STORM MOTION WILL REMAIN FAIRLY SLOW AND POTENTIAL FOR SOME
TRAINING EXISTS. FOCUS OF ATTENTION THROUGH THIS AFTERNOON WILL BE
THE CANYON COUNTRY IN SOUTHEAST UTAH AND CLOSE TO LAKE POWELL IN
SAN JUAN COUNTY UTAH...ALTHOUGH ANY STORMS THAT FIRE WILL BE
CAPABLE OF PRODUCING HEAVY RAINFALL. CONFIDENCE INCREASING THAT
WE WILL BE HAVING SOME FLASH FLOOD PROBLEMS BEGINNING THIS
AFTERNOON AND CONTINUING THROUGH MONDAY EVENING. AS A
RESULT...WILL BE ISSUING A FLASH FLOOD WATCH FOR EAST CENTRAL AND
SOUTHEAST UTAH AND PORTIONS OF SOUTHWEST COLORADO...MAINLY FOR THE
BEDROCK AND SLICK ROCK AREAS NORTH OF CORTEZ AND SOUTH OF
GATEWAY. WITH CLOUD COVER AND GREATER SFC MOISTURE IN
PLACE...TEMPS DROP AT LEAST 5 DEGREES ACROSS THE BOARD...BRINGING
AN END TO THE RECENT STRETCH OF 90 PLUS DAYS IN GRAND JUNCTION.
A WET WEEK IS IN STORE FOR THE REGION WITH THE EASTERN UTAH AND
THE SOUTHERN SLOPES OF OF THE SOUTHERN AND CENTRAL MOUNTAINS
FAVORED FOR HEAVY RAINFALL. MODELS REMAIN IN GOOD AGREEMENT.
SUNDAY NIGHT INTO MONDAY THE PACIFIC UPPER LOW TRACKS THROUGH THE
NORTHERN ROCKIES AND ONTO THE NORTHERN PLAINS LEAVING A VERTICALLY
STACKED TROUGH IN THE GREAT BASIN CENTERED OVER LAS VEGAS. THIS
PRODUCES ENHANCES S-SW MOIST AND PERTURBED FLOW INTO EASTERN UTAH.
PRECIPITABLE WATER SURGES TO 1.4 INCHES IN SE UTAH TO OVER AN INCH
NORTH OF CRAIG. STORM MOTION IS TO THE NE AT 20KTS WHICH WILL
LIMIT RAINFALL FROM ANY ONE STORM BUT TRAINING WILL QUICKLY ADD
UP. DIVERGENCE ALOFT IN THE RIGHT ENTRANCE REGION OF A WEAK 40KT
JET OVER NE UTAH- FAR NW CO WILL ENHANCE SHOWERS THERE. CLOUDS
AND SHOWERS WILL DROP MONDAY TEMPERATURES BELOW NORMAL FOR THE
FIRST TIME THIS MONTH.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 353 AM MDT SUN SEP 8 2013
SOME CHANGES IN STORE IN THE PATTERN THROUGH TUESDAY NIGHT BUT
WIDESPREAD SHOWERS AND STORMS WILL CONTINUE. EAST LOW LEVEL FLOW
SETS UP MONDAY NIGHT THAT MAY LIMIT RAINFALL AMOUNTS. BUT WEAK
COLD ADVECTION ALOFT MAY PRODUCE ENOUGH FORCING TO OVERCOME THIS.
MODELS ARE NOW PRODUCING SOME LIGHT SNOWFALL ABOVE TIMBERLINE
ESPECIALLY MONDAY NIGHT. DIVERGENCE ALOFT REMAINS OVER NE UTAH.
TUESDAY THE REMNANTS OF WHAT WAS TS LORENA...CURRENTLY ALONG THE
SOUTHERN BAJA... WILL BE PULLED INTO FOUR CORNERS ENHANCING
ALREADY DEEP MOISTURE. STORM MOTION OF TO THE NORTH AT 15-20 MPH
WILL AGAIN MAKE FLOODING DIFFICULT FROM ANY ONE STORM...BUT MUD
FLOWS WILL THREATEN FROM TWO DAYS OF HEAVY RAIN ESPECIALLY ALONG
SOUTH FACING SLOPES. SCATTERED TO WIDESPREAD STORMS CONTINUE INTO
WEDNESDAY MORNING.
MOIST AND UNSETTLED CONDITIONS REMAIN IN PLACE THROUGH THURSDAY AS
REMNANTS OF TROPICAL STORM LORENA CONTINUE TO PUSH NORTHEAST THROUGH
THE FORECAST AREA. THIS WILL KEEP THE POTENTIAL FOR HEAVY RAIN IN
THE FORECAST. SUBTLE DRYING ADVERTISED IN THE MOST RECENT MEDIUM
RANGE MODELS AS WE CLOSE OUT THE WORK WEEK. HOWEVER...ANOTHER
PACIFIC TROUGH SWINGS INLAND OVER THE WEEKEND AND WILL DRAW UP AT
LEAST ONE MORE ROUND MONSOONAL MOISTURE. TEMPERATURES WILL BE
RUNNING NEAR SEASONAL NORMS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 353 AM MDT SUN SEP 8 2013
SCATTERED SHOWERS AND THUNDERSTORMS WILL BE FOUND ACROSS ALL OF
EASTERN UTAH AND WESTERN COLORADO THROUGH TONIGHT. HEAVY
RAIN...GUSTY AND ERRATIC WINDS TO 40 MPH AND SMALL HAIL WILL
ACCOMPANY THE STRONGEST STORMS. EXPECT AREAS OF MVFR CIGS AND
VSBYS WITH THE STRONGER STORMS...ALONG WITH LOCAL MOUNTAIN
OBSCURATION. THESE CONDITIONS WILL LIKELY CONTINUE THROUGH LATE
MONDAY EVENING.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...FLASH FLOOD WATCH FROM NOON MDT TODAY THROUGH MONDAY EVENING FOR
COZ020-021.
UT...FLASH FLOOD WATCH FROM NOON MDT TODAY THROUGH MONDAY EVENING FOR
UTZ022-025-027>029.
&&
$$
SHORT TERM...JDC/JOE
LONG TERM...JOE/JDC
AVIATION...JDC
AREA FORECAST DISCUSSION
NWS TAUNTON MA
734 AM EDT SUN SEP 8 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS SOUTHERN NEW ENGLAND TODAY AND MAY BE
PRECEDED BY A BRIEF SHOWER. HIGH PRESSURE WILL BRING COOLER
WEATHER TONIGHT AND MONDAY. WARMER AND MORE HUMID WEATHER WILL
RETURN BY MIDWEEK AS THIS HIGH BECOMES CENTERED OFFSHORE. ANOTHER
COLD FRONT MAY BRING SHOWERS AND THUNDERSTORMS LATER THIS WEEK
BEFORE ANOTHER HIGH PRESSURE RETURNS FOR NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
730 AM UPDATE...MINOR TWEAKS TO THE TIMING OF A COLD FRONT THIS
MORNING...AND THE RAINFALL CHANCES WHICH GO WITH IT. STILL LOOKS
LIKE ANY SHOWERS/SPRINKLES WE SEE TODAY WILL BE THIS MORNING...
WITH CLEARING AND GUSTY WINDS FOR THIS AFTERNOON FROM NORTHWEST TO
SOUTHEAST.
OTHERWISE...ADJUSTED NEAR-TERM CONDITIONS TO BRING THEM IN LINE
WITH OBSERVED TRENDS.
PREVIOUS DISCUSSION...
SMALL BAND OF SPRINKLES WAS PUSHING SOUTHWARD THROUGH REGION EARLY
THIS MORNING...ASSOCIATED WITH WEAK SURFACE TROUGH. EXPECT THIS
BAND TO DIMINISH AS IT REACHES S COAST PER HRRR. MEANWHILE NOT
MUCH HAPPENING UPSTREAM WITH COLD FRONT WHICH EXTENDED FROM
WESTERN AND NORTHERN NY INTO NORTHERN NEW ENGLAND. HRRR SEEMS TO
HAVE CORRECTLY BACKED OFF ON AREAL EXTENT OF SHOWERS AS FRONT
REACHES SOUTHERN NEW ENGLAND THIS MORNING...SO AM ONLY MENTIONING
ISOLATED SHOWERS AS ANY ACTIVITY WILL BE WIDELY SCATTERED.
FRONT SHOULD PUSH OFF S COAST EARLY THIS AFTERNOON. FAIRLY STRONG
COLD ADVECTION ASSOCIATED WITH HIGH PRESSURE BUILDING IN FROM
GREAT LAKES WILL RESULT IN A FEW HOURS OF BREEZY CONDITIONS LATER
THIS AFTERNOON...ESPECIALLY NEAR COAST. CLEARING WILL ALSO SET IN
FROM NW TO SE AS DRIER AIR ARRIVES.
GFS/NAM MOS ARE AT ODDS WITH EACH OTHER TODAY WITH NAM RUNNING
SEVERAL DEGREES WARMER AND GFS SEEMING TO BE TOO LOW CONSIDERING
AFTERNOON CLEARING. STAYED WITH CURRENT FORECAST OF HIGHS IN 60S
AND 70S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
WINDS DIMINISH QUICKLY THIS EVENING AS GRADIENT WEAKENS IN
RESPONSE TO HIGH PRESSURE BECOMING CENTERED OVER PA OVERNIGHT. DRY
AIRMASS IN PLACE WILL ALLOW FOR IDEAL RADIATIONAL COOLING.
CERTAINLY CAN SEE USUAL COLD SPOTS DROPPING INTO UPPER 30S BUT
WIDESPREAD MID 30S MAY BE A STRETCH...SO AM NOT ISSUING ANY FROST
ADVISORIES AT THIS TIME IN COLLABORATION WITH ALY/GYX. OTHERWISE A
CHILLY NIGHT AHEAD WITH LOWS IN 40S TO AROUND 50.
PLENTY OF SUNSHINE EXPECTED MON AS AIRMASS REMAINS DRY THROUGH
COLUMN PER MODEL CROSS SECTIONS. HIGH PRESSURE GRADUALLY HEADS
OFFSHORE RESULTING IN LIGHT S/SW FLOW...BUT NOT SOON ENOUGH TO
PREVENT SEA BREEZE DEVELOPMENT NEAR E MA COAST. LEANED CLOSER TO
GFS MOS FOR HIGHS /UPPER 60S COAST AND LOWER 70S INLAND/ WHICH
SEEMED MORE REASONABLE.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
* A RETURN TO HEAT AND HUMIDITY MID WEEK
* CHANCE OF THUNDERSTORMS AS A COLD FRONT MOVES THROUGH THU-FRI
08/00Z MODELS REMAIN IN ABOVE AVERAGE AGREEMENT THROUGH THIS
PORTION OF THE FORECAST. THERE ARE SOME DIFFERENCES WITH THE
TIMING OF A COLD FRONT LATER THIS WEEK...AS WELL AS HOW ACTIVE A
PREFRONTAL TROUGH WILL BE AROUND WEDNESDAY. WILL GENERALLY FOLLOW
THE CONSENSUS TIMING...WITH SOME TWEAKS DETAILED BELOW.
MONDAY NIGHT-TUESDAY...A WARM FRONT APPROACHES OUR REGION WITH A
HIGH PRESSURE CENTERED SOUTH OF NOVA SCOTIA. MID AND HIGH LEVEL
CLOUDS SHOULD MOVE IN. TEMPERATURES EXPECTED TO BE RIGHT AROUND
NORMAL FOR SEPTEMBER.
TUESDAY...A WARM FRONT MOVES NORTHWARD THROUGH SOUTHERN NEW
ENGLAND...WITH A RETURN TO WARMER SOUTHWEST FLOW AT THE SURFACE.
TEMPERATURES WILL START WARMING TO ABOVE NORMAL. WITH THE ADDED
MOISTURE IN THE ATMOSPHERE AND THE HEATING AT THE SURFACE...
EXPECTING SOME DIURNAL CLOUDS TO DEVELOP. 08/00Z ECMWF CONTINUES
THE TREND FROM ITS PREVIOUS RUN AND IS MUCH MORE AGGRESSIVE THAN
THE OTHER GUIDANCE DEVELOPING SHOWERS. WITH THE BEST DYNAMICS
LIKELY REMAINING TO OUR NORTH AND WEST...THINK THIS MODEL IS
OVERDONE. THINKING MORE ALONG THE LINES OF ISOLATED TO SCATTERED
SPRINKLES AT THIS POINT.
WEDNESDAY...THERE START TO BE SOME TIMING DIFFERENCES HERE IN THE
MODELS REGARDING THE ONSET OF SHOWERS AND THUNDERSTORMS ACROSS THE
REGION. THE GFS STARTS EXHIBITING SOME QPF WEDNESDAY AFTERNOON
ACROSS THE NORTHWESTERN ZONES AND THEN BUILDING EASTWARD THROUGH THE
AREA THROUGH WEDNESDAY NIGHT. THE ECMWF KEEPS THIS DAY DRY AND
STARTS MOVING SHOWERS INTO THE NORTHWESTERN ZONES LATE WEDNESDAY
NIGHT...KEEPING THE BULK OF THE RAINFALL TO THURSDAY.
WHILE THERE SHOULD BE A PREFRONTAL TROUGH NEARBY...THERE IS STILL
NOT A LOT OF SYNOPTIC SUPPORT OR INSTABILITY. MID LEVEL LAPSE
RATES IN THE GFS ARE A LITTLE MORE UNSTABLE THAN MOIST ADIABATIC.
WILL WE CANNOT RULE SOME ISOLATED SHOWERS OR THUNDERSTORMS...
LEANING AWAY FROM THE WIDESPREAD DOWNPOURS DEPICTED BY THE GFS.
THIS WILL BE THE WARMEST...AND LIKELY THE MOST HUMID...DAY OF THIS
WEEK.
THURSDAY...ANOTHER WARM DAY WITH UNCOMFORTABLE DEWPOINTS. A COLD
FRONT IS EXPECTED THURSDAY NIGHT INTO FRIDAY MORNING. DEPENDING
ON ITS TIMING...STRONG THUNDERSTORMS ARE A RISK AGAIN THURSDAY WITH
A SURFACE TROUGH AHEAD OF THE FRONT INDUCING SURFACE CONVERGENCE
AND DESTABILIZATION. ALSO...AMPLE CAPE...BORDERLINE SHEAR AND
DECENT SEVERE PARAMETERS SHOULD EXIST. THE BIG QUESTION...ALONG
WITH FRONTAL TIMING...IS CLOUD COVER. IT MAY BE TOO CLOUDY TO
GENERATE MUCH SURFACE DESTABILIZATION.
FRIDAY-SATURDAY...ANY LEFTOVER SHOWERS EXIT OFF THE COAST FRIDAY
MORNING WITH THE FRONT AND A HIGH PRESSURE TAKES ITS PLACE.
SATURDAY MORNING SHOULD START ANOTHER PERIOD OF BELOW NORMAL
TEMPERATURES. THE MOIST AIR SHOULD LEAVE WITH THE COLD FRONT AS
THIS HIGH PRESSURE BRINGS IN DRIER CONDITIONS.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH MONDAY/...HIGH CONFIDENCE.
OTHERWISE VFR CIGS AOA 060 THROUGH THIS MORNING WITH SCATTERED
SPRINKLES...PROBABLY NOT ENOUGH TO WET RUNWAYS.
CLEARING THIS AFTERNOON FROM NW TO SE WITH INCREASING N/NW WINDS
GUSTING TO 20-25KT. STRONGEST GUSTS ALONG COAST 21Z-03Z BEFORE
WINDS SUBSIDE. ONCE AGAIN PATCHY FOG WILL BRING LOCAL MVFR/IFR TO
INTERIOR VALLEYS TONIGHT.
VFR MON. SEA BREEZES EXPECTED NEAR E MA COAST 15Z-23Z BEFORE WINDS
BECOME S/SW. SHOULD SEE S/SW WINDS ALL DAY NEAR S COAST.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK...TUESDAY THROUGH THURSDAY...
TUESDAY...HIGH CONFIDENCE. MAINLY VFR. LOW PROBABILITY OF
MVFR/IFR CONDITIONS IN FOG DURING THE OVERNIGHT.
WEDNESDAY AND THURSDAY...MODERATE CONFIDENCE. MAINLY VFR. MODERATE
PROBABILITY OF MVFR/IFR CONDITIONS IN SHRA/TSRA/FG FROM WEDNESDAY
NIGHT INTO THURSDAY.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT TERM /THROUGH MONDAY/...HIGH CONFIDENCE.
EXPANDED SCA TO INCLUDE ALL WATERS EXCEPT NARRAGANSETT BAY FROM
THIS AFTERNOON INTO TONIGHT. WINDS DIMINISH THIS EVENING BUT SEAS
ON OUTER WATERS WILL TAKE MORE TIME TO SUBSIDE BELOW 5 FT.
COLD FRONT CROSSES WATERS LATER THIS MORNING AND EARLY THIS
AFTERNOON WITH NOTHING MORE THAN BRIEF SHOWER. LIGHT W/SW WINDS
AHEAD OF FRONT SHIFT TO N/NW WITH PERIOD OF 25KT GUSTS EXPECTED
FROM MID AFTERNOON THROUGH EARLY TONIGHT...ESPECIALLY ON E MA
WATERS AND AROUND CAPE COD.
TIMING OF HIGHER GUSTS ON BUZZARDS BAY AND VINEYARD SOUND WILL
COINCIDE WITH INCOMING TIDE AGAINST N WIND /LOW TIDE AROUND 4 PM
AND HIGH TIDE AROUND 1030 PM/. THIS WILL RESULT IN STEEP WAVES
LATER THIS AFTERNOON AND ESPECIALLY THIS EVENING. SIMILAR
SITUATION ON CAPE COD BAY WITH DEPARTING TIDE AGAINST N WIND LATER
THIS AFTERNOON /HIGH TIDE AROUND 2 PM AND LOW TIDE AROUND 8 PM/.
HIGH PRESSURE SLOWLY HEADS OFFSHORE MON WITH LIGHT S/SW FLOW...
BUT SEA BREEZE EXPECTED ALONG E MA COAST BEFORE WINDS TURN S
TOWARD EVENING.
OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...
QUIET BOATING WEATHER EXPECTED TUESDAY. SEAS INCREASE TO AROUND
5-6 FEET ACROSS THE OUTER WATERS WEDNESDAY INTO THURSDAY IN
ADVANCE OF A COLD FRONT MOVING TOWARDS THE WATERS. WINDS HAVE THE
POTENTIAL TO GUST TO NEAR 25 KTS EACH AFTERNOON TUESDAY THROUGH
THURSDAY...PARTICULARLY ACROSS THE NEAR SHORE WATERS SURROUNDING
CAPE COD AND THE ISLANDS. THERE IS A LOW PROBABILITY OF SHOWERS
AND THUNDERSTORMS OVER THE WATERS THURSDAY.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT EDT
TONIGHT FOR ANZ231>235-237.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 8 PM EDT THIS
EVENING FOR ANZ230.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM EDT
MONDAY FOR ANZ250.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO MIDNIGHT EDT
TONIGHT FOR ANZ251.
SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EDT MONDAY
FOR ANZ254>256.
&&
$$
SYNOPSIS...BELK/JWD
NEAR TERM...BELK/JWD
SHORT TERM...JWD
LONG TERM...BELK
AVIATION...BELK/JWD
MARINE...BELK/JWD
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
731 AM CDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 723 AM CDT SUN SEP 8 2013
THE CONVECTION HAS EXITED THE AREA AND A PERIOD OF QUIET WX IS
EXPECTED THROUGH THE EARLY AFTERNOON. PER THE RAP/WRF TRENDS THE
LOW CLOUDS COMING OFF LAKE MICHIGAN ARE MOVING JUST A BIT FASTER
THAN EXPECTED. HOWEVER...WITH THE SUN NOW UP THE SOUTHWARD
EXPANSION OF THE CLOUDS SHOULD BE HALTED. CLOUD COVER WILL MAKE
TEMPERATURES INTERESTING TODAY. THOSE AREAS THAT HAVE CLOUDS
SHOULD REMAIN IN THE UPPER 60S TO LOWER 70S FOR A GOOD PORTION OF
THE MORNING BEFORE RISING.
CONVECTION THIS AFTERNOON IS QUESTIONABLE. THERE IS A WARM LAYER
ALOFT THAT MAY PREVENT ANY CONVECTION FROM OCCURRING. IF
CONVECTION DOES OCCUR THE MOST LIKELY AREA WILL BE SOUTH OF I-80
WHERE THE STRONGER DIFFERENTIAL HEATING WILL OCCUR.
&&
.SYNOPSIS...
ISSUED AT 315 AM CDT SUN SEP 8 2013
06Z SFC ANALYSIS HAS A WEAK LOW NORTHEAST OF KOTM WITH A FRONT
PASSING NORTH OF THE QUAD CITIES AND EAST INTO NORTHERN INDIANA. A
COLD FRONT RAN FROM THE LOW SOUTHWEST TO THE NE/KS LINE. AN
INVERTED TROF RAN FROM THE LOW INTO SOUTHEAST MINNESOTA WHILE
ANOTHER TROF RAN SOUTHEAST FROM THE LOW INTO CENTRAL ILLINOIS. DEW
POINTS WERE IN THE 60S ACROSS THE MIDWEST WITH POCKETS OF 70
AROUND THE LOW AND COLD FRONT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT SUN SEP 8 2013
THE CONCERNS ARE THE CONVECTION IN THE SOUTHERN CWFA AND THE
APPROACHING LOW CLOUDS FROM WISCONSIN.
THE CONVECTION AROUND KGBG AND NOW IMMEDIATELY WEST OF THERE IS
CONTINUOUSLY FORMING AND MOVING OVER THE SAME AREAS. THE CULPRIT
IS A COMBINATION OF CONVERGENCE AROUND THE TROF OVER THAT AREA.
PER THE RAP TRENDS THIS IS EXPECTED TO CONTINUE FOR THE NEXT
SEVERAL HOURS BEFORE WEAKENING. THUS SOME ISOLATED AREAS WILL SEE
LOCALLY HEAVY RAINFALL THROUGH SUNRISE.
THE RAP IS DOING A RESPECTABLE JOB OF DEPICTING THE LOW CLOUDS
APPROACHING FROM WISCONSIN AND WILL ENTER THE NORTHERN CWFA PRIOR
TO SUNRISE.
FOR TODAY...THE CONVECTION IN THE SOUTHERN CWFA SHOULD DISSIPATE
AFTER SUNRISE WHILE LOW CLOUDS CONTINUE TO OVERSPREAD ACROSS THE
NORTHEAST THIRD TO 40 PERCENT OF THE CWFA. THE FRONT WILL SLOWLY
SAG SOUTH AND IS EXPECTED TO CLEAR THE CWFA DURING THE AFTERNOON.
DIURNAL HEATING IS EXPECTED TO ALLOW VERY ISOLATED SHOWERS AND
THUNDERSTORMS TO DEVELOP DURING THE AFTERNOON IN THE SOUTHERN CWFA
WHERE CONVECTIVE TEMPERATURES SHOULD BE ACHIEVED IN SPITE OF THE
WARM AIR ALOFT.
TONIGHT...MAINLY QUIET AND DRY CONDITIONS ARE EXPECTED AS THE FRONT
BEGINS MOVING BACK NORTH AS A WARM FRONT. ..08..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 315 AM CDT SUN SEP 8 2013
TEMPERATURES WILL BE THE MAIN CONCERN MONDAY AND TUESDAY AS VERY
WARM AIR SURGES NORTHEAST BEHIND A WARM FRONT MOVING THROUGH THE
FORECAST AREA BY EARLY MONDAY AFTERNOON. H8 TEMPS ARE FORECAST TO
INCREASE INTO THE LOW TO MID 20/S IN THE WARM SECTOR BY MONDAY
AFTERNOON. MIXING THESE TEMPERATURES TO THE SURFACE YIELDS MAX
TEMPS IN THE MID TO UPPER 90S WHICH LOOKS REASONABLE FOR THE
SOUTHWEST 2/3RDS. WITH THE WARM FRONT MOVING OUT OF THE NORTHEAST
COUNTIES DURING THE AFTERNOON...HIGHS WERE KEPT IN THE LOW 90S.
DEWPOINTS SHOULD BE IN THE MID OR UPPER 60S MONDAY WHICH WILL BE
HIGH ENOUGH TO PRODUCE HEAT INDEX VALUES AROUND 100 DURING THE
AFTERNOON. BY TUESDAY A COLD FRONT WILL BE JUST NORTHWEST OF THE
AREA AT 12Z AND WILL MOVE SLOWLY SOUTH REACHING THE SOUTHEASTERN
COUNTIES BY LATE AFTERNOON. AREAS ALONG AND SOUTH OF HIGHWAY 30
WILL HAVE PLENTY OF TIME TO HEAT UP AND SHOULD SEE ANOTHER DAY OF
MID 90 TEMPERATURES. TO THE NORTH WITH THE FRONT MOVING THROUGH
EARLY IN THE DAY...HIGHS SHOULD BE AROUND 90. SOUTHWEST WINDS AHEAD
OF THE FRONT ARE PROGGED TO TAP DRIER AIR OVER THE
PLAINS...KEEPING DEWPOINTS LOWER THAN THOSE EXPECTED ON MONDAY.
THE DRIER AIR WILL KEEP HEAT INDEX VALUES UNDER 100. HIGHS IN THE
90S MONDAY AND TUESDAY WILL BE CLOSE TO RECORD HIGHS FOR THE 9TH
AND 10TH OF SEPTEMBER. MONDAYS RECORDS ARE AROUND 100 AND SHOULD
BE JUST OUT OF REACH BUT SLIGHTLY COOLER RECORDS FOR TUESDAY WILL
BE ATTAINABLE ESPECIALLY AT MOLINE AND BURLINGTON. SEE THE CLIMATE
SECTION BELOW FOR MONDAY/S AND TUESDAY/S RECORD HIGHS AND DATE OF
THE LAST OCCURRENCE.
THE RAIN THREAT WILL BE NIL THROUGH EARLY TUESDAY AFTERNOON. THEN
JUST A SLIGHT CHANCE NORTH PRIOR TO 00Z WEDNESDAY. THE WARM SECTOR
SHOULD BE CAPPED...AND AS STATED ABOVE DEWPOINTS WILL BE DRYING
OUT SOME AHEAD OF THE FRONT. THE BEST POTENTIAL FOR RAIN WILL BE
POST FRONTAL WHERE LOW LEVEL MOISTURE WILL BE POOLING AND THE MID
LEVEL CAP STARTS TO ERODE. MODELS WERE ALSO SHOWING SOME DEEP
LAYER FGEN IN THE ENTRANCE REGION OF A H3 80KT JET STREAK OVER MN
AND WI WHICH SHOULD CONTRIBUTE TO THE POST FRONTAL FORCING.
DESPITE THESE SIGNALS FAVORING RAIN...THERE IS STILL A WIDE RANGE
OF QPF FORECASTS AMONG THE MODELS WITH THE LATEST ECM RUN DRY FOR
NEARLY ALL OF THE CWFA. WITH THE MODELS STILL LENDING A LOT OF
UNCERTAINTY TO THE PRECIP FORECAST FOR TUESDAY NIGHT AND WEDNESDAY...
HAVE KEPT THE POPS IN THE CHANCE CATEGORY.
THE FRONT WILL BE SOUTH OF THE AREA BY TUESDAY EVENING ENDING ANY
RAIN THREAT FOR THE REST OF THE WEEK. HIGH PRESSURE SLIDING
SOUTHEAST THROUGH THE GREAT LAKES BY LATE WEEK WILL BRING COOL DRY
AIR TO THE REGION. BY FRIDAY AND SATURDAY WE SHOULD SEE HIGHS IN
THE 70S OVER THE ENTIRE AREA WITH LOWS IN THE 40S AND 50S BY
SATURDAY MORNING.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 723 AM CDT SUN SEP 8 2013
LOW CLOUDS COMING OFF LAKE MICHIGAN WILL CREATE MVFR/IFR
CONDITIONS AT KCID/KMLI/KDBQ. KBRL IS EXPECTED TO REMAIN VFR. THE
MVFR/IFR CONDITIONS WILL SLOWLY IMPROVE TO VFR BY 00Z/09. ISOLATED
SHRA AND POSSIBLY A TSRA MAY DEVELOP AFT 18Z/08 BUT THE
PROBABILITY IS QUITE LOW THAT A TAF SITE WILL BE AFFECTED.
&&
.CLIMATE...
ISSUED AT 113 AM CDT SUN SEP 8 2013
RECORD HIGHS FOR SEPTEMBER 9...
MOLINE.........99 IN 1933
CEDAR RAPIDS...98 IN 1955
DUBUQUE........97 IN 1955
BURLINGTON.....100 IN 1912
RECORD HIGHS FOR SEPTEMBER 10...
MOLINE.........95 IN 1983
CEDAR RAPIDS...98 IN 1931
DUBUQUE........97 IN 1895
BURLINGTON.....97 IN 1933
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...DLF
AVIATION...08
CLIMATE...DLF
AREA FORECAST DISCUSSION
NWS DES MOINES IA
638 AM CDT SUN SEP 8 2013
.SHORT TERM.../TODAY /...
ISSUED AT 334 AM CDT SUN SEP 8 2013
THE COLD FRONT HAS PUSHED THROUGH ALL BUT THE FAR SOUTHEAST CORNER
OF IOWA WITH LIGHT NLY WIND OVER THE CWA. WINDS WILL VEER TO NELY
AND EVENTUALLY ELY. LOWERED TEMPS A BIT WITH THE STRONGER PUSH OF
COOLER AIR AND THE PROSPECT FOR MORE CLOUDINESS. AREAS OF CONCERN
ARE THREE FOLD TODAY. FIRST IS THE STRATUS DECK ENTERING NERN IA
THIS MORNING AND HOW FAR IT WILL PUSH TO THE SOUTHWEST. THINKING IS
THAT IT WILL PUSH ABOUT A THIRD OF THE WAY ACROSS THE STATE BEFORE
IT STARTS TO BREAK UP. TEMPS MAY WELL STRUGGLE TO MAKE 80 IN THE
FAR NERN PART OF THE CWA. SECOND CONCERN IS WITH THE MCS OVER THE
DAKOTAS. SPILL OFF CLOUDINESS MAY WELL HAVE A SIGNIFICANT IMPACT ON
TEMPS. THOUGH WE ARE STARTING OUT QUITE WARM...IT WOULD SEEM THAT
FEW PLACES WILL BREAK OUT OF THE 80S...AND THAT WILL BE IN THE FAR
SOUTHWEST. THIRD CONCERN IS THE HRRR DEVELOPMENT OF SHOWER ACTIVITY
OVER WESTERN IA THIS MORNING. DON`T SEE A LOT OF SUPPORT FOR THAT
EVEN GIVEN SOME AC AND VIRGA DEVELOPMENT OVER EASTERN NEBRASKA AT
PRESENT. THERE IS MORE SUPPORT THERE AND IT IS STRUGGLING WITH THE
EML IN PLACE. WITH THAT SAID...WILL GO A TOUGH ABOVE MOS GUIDANCE
FOR HIGHS TODAY. LEFT POPS OUT EXCEPT FOR THE POTENTIAL OF SOME
EARLY MORNING TSRA OVER THE EXTREME SOUTHEAST AS THESE HAVE HAD A
TENDENCY TO BACK DEVELOP THROUGH THE EARLY MORNING HOURS.
.LONG TERM.../TONIGHT THROUGH FRIDAY/...
ISSUED AT 334 AM CDT SUN SEP 8 2013
STRONG WARM ADVECTION WILL PASS THROUGH CENTRAL IOWA LATE TONIGHT
AND THROUGH THE DAY ON MONDAY AS LOW PRESSURE MOVES THROUGH THE
DAKOTAS AND INTO MINNESOTA. A WELL MIXED PROFILE WILL BE IN PLACE
BY THE AFTERNOON FUELED BY BREEZY SOUTHWEST WINDS. DEWPOINTS WILL
DROP INTO THE 50S TO LOWER 60S AS THE PROFILES MIX IN THE
AFTERNOON. HIGH TEMPERATURES WILL JUMP INTO THE MID 90S TO
POSSIBLY LOW 100S BY MID AFTERNOON. THESE READINGS ARE NEAR TO
ABOVE RECORD VALUES. THE CURRENT LATEST 100 DEGREE DAY AT DES
MOINES OCCURRED ON SEPTEMBER 7TH 1939 THEREFORE IF THE FORECAST OF
100 VERIFIES...IT WILL ECLIPSE THAT MARK. BOTH WATERLOO (SEPTEMBER
15TH 1927) AND OTTUMWA (SEPTEMBER 11TH 1936) HAVE HAD 100 DEGREE
DAYS BEYOND THIS POINT.
A FRONTAL BOUNDARY WILL GRADUALLY SAG THROUGH IOWA MONDAY NIGHT
THROUGH TUESDAY NIGHT AS THE AREA OF LOW PRESSURE SHIFTS TO THE
EAST. THE BOUNDARY WILL BE QUITE SLOW TO MOVE SOUTH AS THE UPPER
LEVEL RIDGE STUBBORNLY GIVES WAY TO A SHORT WAVE MOVING EAST ALONG
THE US/CANADIAN BORDER. THE PRIMARY ENERGY WITH THIS SYSTEM WILL
BE PASSING TO THE NORTH OF THE STATE NEAR THE UPPER WAVE AND IN
THE VICINITY OF THE RIGHT REAR QUAD OF THE UPPER JET. THE MAIN
POTENTIAL FOR PRECIPITATION WILL BE POST SFC FRONTAL AND CLOSER TO
THE 850 MB BOUNDARY LATE TUESDAY INTO TUESDAY NIGHT. CONFIDENCE IS
NOT HIGH THAT ANY BENEFICIAL RAIN WILL OCCUR WITH THIS SYSTEM AND
ESPECIALLY IN THE EXPANDING D2 DROUGHT REGION OVER THE CENTRAL AND
WEST CENTRAL AREAS. A TRANSITION TO NORTHWEST FLOW TUESDAY NIGHT
AND WEDNESDAY WILL FINALLY PUSH THE BOUNDARY SOUTH OF THE STATE
AND THIS WILL ALLOW A LARGE CANADIAN HIGH PRESSURE SYSTEM TO DROP
INTO THE UPPER MIDWEST AND WESTERN GREAT LAKES REGION FOR THE END
OF THE WEEK. THE HIGH WILL BRING A REFRESHING BLAST OF COOLER AIR
WITH HIGHS IN THE 70S BY FRIDAY AND OVERNIGHT LOWS POSSIBLE
DROPPING INTO 40S OVER THE NORTH.
&&
.AVIATION...08/12Z
ISSUED AT 635 AM CDT SUN SEP 8 2013
COLD FRONT ALONG THE IA/MO BORDER WILL MOVE LITTLE TODAY...THEN
BEGIN TO LIFT NORTH AS A WARM FRONT LATE TONIGHT INTO MON.
MULTIPLE CLOUDS LAYERS OVER THE STATE TODAY...BUT ONLY ONE OF AVN
SIGNIFICANCE IS TH STRATUS DECK ENTERING IA FROM THE NORTHEAST.
FEEL THE STRATUS WILL REMAIN NORTH OF KOTM, MAY JUST BRUSH
KDSM...AND BE A CIG EVENT THROUGH THE MORNING INTO THE EARLY
AFTERNOON AT THE OTHER THREE SITES. STRATUS MAY REFORM OVER THE
NERN TAF SITES LATE TONIGHT TO THE NORTH OF THE WARM FRONT. MVFR
FOG IS EXPECTED ACROSS THE STATE.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MS SEP 13
LONG TERM...DONAVON
AVIATION...MS SEP 13
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
1100 AM EDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 1100 AM EDT SUN SEP 8 2013
14Z SFC ANALYSIS SHOWS A WEAK COLD FRONT POISED TO DROP THROUGH EAST
KENTUCKY TODAY. A SMATTERING OF LIGHT SHOWERS MOVED ACROSS THE AREA
EARLY IN THE MORNING OUT AHEAD OF THIS...ALONG WITH PATCHY FOG...AND
SKIES HAVE TEMPORARILY CLEARED IN THEIR WAKE. TEMPERATURES AND
DEWPOINTS ARE FAIRLY UNIFORM THROUGH THE AREA GENERALLY IN THE LOWER
70S AND UPPER 60S...RESPECTIVELY. THE LATEST NAM12 AND HRRR INDICATE
THAT THE SOUTHERN PARTS OF THE CWA WILL HAVE THE BEST CHANCE OF
SEEING A REDEVELOPMENT OF SHOWERS AND ISOLATED STORMS BY MID
AFTERNOON AS THE FRONT SETTLES ON THROUGH. HAVE GEARED THE NEAR TERM
FORECAST GRIDS TO THIS IDEA...ALLOWING THE INSTABILITY TO BUILD
BEFORE INTRODUCING THUNDER INTO THE WX ONES. MOST PLACES WILL STAY
DRY...WARM..AND HUMID TODAY...THOUGH. A FORTHCOMING ZFP UPDATE WILL
REMOVE THE MORNING FOG WORDING. THE FRESHENED GRIDS HAVE BEEN SENT TO
THE NDFD AND WEB SERVERS.
UPDATE ISSUED AT 657 AM EDT SUN SEP 8 2013
ISOLATED SHOWERS ARE DIMINISHING ACROSS THE AREA AS THE ISENTROPIC
FORCING EASES UP. WILL LET THE FORECAST RIDE AS A FEW SHOWERS MAY BE
SEEN AFTER 12Z BEFORE DRYING UP COMPLETELY UNTIL WE HEAT UP THIS
AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 254 AM EDT SUN SEP 8 2013
THE LATEST SURFACE MAP FEATURES A SURFACE COLD FRONT ALIGNED FROM
NORTHERN NEW ENGLAND DOWN THROUGH THE NORTHERN OHIO VALLEY...WITH AN
AREA OF SURFACE HIGH PRESSURE CONGEALED ACROSS THE SOUTHEASTERN
CONUS. ISENTROPIC LIFT OUT AHEAD OF THE FRONT HAS ALLOWED FOR SOME
NOCTURNAL SHOWER ACTIVITY ALONG AND SOUTH OF THE OHIO
RIVER...INCLUDING PORTIONS OF EASTERN KENTUCKY. THE LATEST NAM12
SEEMS TO HAVE A REASONABLE HANDLE ON THE ISENTROPIC LIFT...ALTHOUGH
ITS QPF IS NOT BEEFY ENOUGH COMPARED TO REALITY.
THE MODELS REMAIN IN GOOD AGREEMENT THROUGH THE SHORT TERM...ALLOWING
THE COLD FRONT TO MAKE IT INTO THE COMMONWEALTH THIS AFTERNOON. POPS
HAVE COME IN LOWER...ESPECIALLY FROM THE NAM12. WILL STICK WITH AT
LEAST ISOLATED CHANCES...ALTHOUGH WILL RESTRICT THE SCATTERED
POTENTIAL TO THE SOUTHEAST TERRAIN COUNTIES GIVEN THE DOWNWARD TREND.
HIGHS WILL BE A BIT WARMER THAN YESTERDAY...WITH MID 80S FOR MOST
LOCATIONS...AND A FEW SPOTS REACHING THE UPPER 80S.
THE FRONT WILL DISSOLVE ACROSS THE AREA INTO THIS EVENING...AND
EXPECT A QUICK DIE OFF IN THE CONVECTION WITH THE LOSS OF HEATING.
LOWS TONIGHT WILL REFLECT THE INCREASING HUMIDITY ACROSS THE
AREA...WITH MID TO UPPER 60S EXPECTED. AN UPPER LEVEL RIDGE WILL MOVE
IN FROM THE WEST ON MONDAY...SO EXPECT THIS TO KEEP A LID ON THE
CONVECTION FOR THE MOST PART...ALTHOUGH COULD SEE A STRAY SHOWER OR
STORM GO UP ALONG THE SOUTHEAST TERRAIN. HIGHS WILL BE A BIT WARMER
STILL...WITH UPPER 80S EXPECTED AND A FEW SPOTS FLIRTING WITH THE 90
DEGREE MARK.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 346 AM EDT SUN SEP 8 2013
THE MODELS START OUT IN GOOD AGREEMENT WITH AND UPPER RIDGE OVER THE
SOUTHEAST WITH AN UPPER TROUGH MOVING EAST ACROSS THE ROCKIES. THERE
IS A BATTLE OF SORTS WITH THE UPPER RIDGE WHICH TRIES TO STAY IN
PLACE AS THE TROUGH TRIES TO DISPLACE IT. BY WEDNESDAY MORNING A COLD
FRONT EXTENDS FROM ACROSS LAKE HURON AND ENDS OVER COLORADO. THE UPPER
RIDGE IS DISPLACED A LITTLE EASTWARD. ALL THIS WHILE...SOME WARM
MOIST AIR IS WORKING ITS WAY INTO THE AREA. THIS WARM MOIST AIR WILL
BE RESPONSIBLE FOR SOME ISOLATED SHOWERS AND THUNDERSTORMS ON TUESDAY
AND THEN SOME SCATTERED STORMS ON WEDNESDAY AFTERNOON AND EVENING.
THE FRONT WILL BE MOVING ACROSS THE AREA ON THURSDAY. CHOSE TO GO
WITH THE SLOWER ECMWF MODEL FOR THE TIMING OF THE FRONT. THE FRONT
WILL BRING A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS TO THE AREA.
THE FRONT WILL BE THROUGH THE AREA BY FRIDAY MORNING AND A SURFACE
HIGH PRESSURE SYSTEM WILL MOVE IN AND DOMINATE UNTIL THE END OF THE
PERIOD. THE OUTLOOK FOR NEXT WEEKEND IS GOOD WITH DRY CONDITIONS AND
HIGH TEMPERATURES IN THE 70S. FOR TEMPS TENDED TO NUDGE TOWARD THE
COOLER MODELS FOR THE HIGH TEMPERATURES.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 657 AM EDT SUN SEP 8 2013
IFR OR WORSE FOG WILL BURN OFF BY AROUND 13Z. A FEW SHOWERS WILL BE
SEEN THROUGH 14Z...MAINLY ALONG AND SOUTH OF THE HAL ROGERS PARKWAY
AND HIGHWAY 80 CORRIDORS...BEFORE DIMINISHING. A COLD FRONT WILL
BRING A SMALL THREAT OF CONVECTION TO THE AREA THIS AFTERNOON. WILL
ALLOW FOR SOME VCSH IN THE TAFS. ONCE WE LOSE HEATING...SKIES WILL
CLEAR OUT WITH FOG LIKELY SEEN ONCE AGAIN BETWEEN 06 AND 12Z.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...GEOGERIAN
LONG TERM...JJ
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION...UPDATED
NWS GAYLORD MI
942 AM EDT SUN SEP 8 2013
.SYNOPSIS...
ISSUED AT 304 AM EDT SUN SEP 8 2013
HIGH PRESSURE PUSHING INTO THE STATE IS BRINGING WITH IT
SIGNIFICANTLY COOLER AND DRIER AIR TODAY. THE WARM AIR WILL
BEGIN TO RETURN MONDAY AS A WARM FRONT MOVES TOWARDS THE REGION.
THIS WILL BRING RENEWED CHANCES FOR SHOWERS AND THUNDERSTORMS.
WARM AND MUGGY CONDITIONS WILL PERSIST INTO TUESDAY BEFORE ANOTHER
COLD FRONT ARRIVES LATE TUESDAY. MUCH COOLER AIR WILL MOVE INTO
NORTHERN MICHIGAN TO END THE WEEK.
&&
.UPDATE...
ISSUED AT 939 AM EDT SUN SEP 8 2013
CHANGES THIS HOUR: PRIMARY CHANGES WILL BE TO CLOUD COVER THROUGH
THE DAY...WITH RECENT OBSERVATIONS AND NEAR TERM RAP BUFR PROGS
SUGGESTING THAT WE/LL BUBBLE UP A BIT OF STCU BEFORE A GRADUAL
CLEARING TREND TAKES PLACE THIS AFTERNOON. OVERALL...THIS RESULTS
IN PRETTY MINOR CHANGES TO THE GOING FORECAST...WITH A PARTLY
SUNNY DAY EXPECTED FOR MOST. TEMPS LOOK ON TRACK TO REACH WITHIN A
FEW DEGREES OF THE 70F MARK.
UPDATE ISSUED AT 645 AM EDT SUN SEP 8 2013
STRONG HIGH PRESSURE...SUBSIDENCE AND DRY AIR THRU THE COLUMN
CONTINUES TO BUILD SOUTHWARD OUT OF ONTARIO AND INTO MICHIGAN
EARLY THIS MORNING. A FEW LOW CLOUDS REMAIN ACROSS FAR SRN
SECTIONS OF OUR CWA...BUT THOSE CLOUDS WILL SLIDE FURTHER SOUTH AS
DRIER AIR CONTINUES TO BUILD SOUTHWARD. ALSO...THE START OF
DAYTIME HEATING WILL LEND TO THE DISSIPATION OF RESIDUAL LOW
CLOUDS THRU DIURNAL MIXING ONCE THE SUN RISES. THE REST OF THE DAY
WILL BE SUNNY BUT NOT AS WARM AND HUMID AS YESTERDAY. HIGH TEMPS
THIS AFTERNOON WILL ONLY WARM INTO THE MID 60S TO LOWER 70S.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 304 AM EDT SUN SEP 8 2013
CURRENTLY, THE 500 MB RIDGE TO THE WEST LOOKS TO BE IN THE
BEGINNING STAGES OF FLATTENING AT THE LEAST AS THE WESTERN CUTOFF
LOW PUSHES INTO THE PAC NORTHWEST. TO THE EAST THE 500 MB TROUGH
LOOKS TO BE HOLDING IN PLACE. THIS SETS UP THE UPPER GREAT LAKES
FOR NORTHWEST FLOW/WARM ADVECTION PATTERN OVER THE NEXT COUPLE OF
DAYS. HOWEVER, IT THE VERY NEAR TERM (TODAY/TONIGHT), HIGH
PRESSURE WILL BE THE DOMINATE FEATURE.
TODAY...THE DRIER AIR, AS NOTED IN PREVIOUS UPDATES, IS MAKING ITS
WAY INTO THE N LOWER NOW, AS EVIDENT ON THE IR IMAGE. THE CLEARING
LINE HAS MADE IT TO ROUGHLY TO A LINE FROM APN TO FKS. THERE WAS A
CONCERN AT THE OUTSET OF THE EVENING FOR FOG, FROM THE RATHER
SOUPY AIR MASS THAT WAS LEFT FROM THE INITIAL SFC TROUGH. HOWEVER,
A SECOND, WEAKER TROUGH, USHERED IN THE DRIER, AND "BREEZIER"
AIR MASS. WITH THE WINDS OVER LAND, FROM THE TIGHTER GRADIENT,
HOLDING AROUND 5 TO 10 KNOTS, THIS HAS KEPT THE FOG FROM FORMING,
AND LEFT LOW CLOUDS BEHIND THE BOUNDARY. NOW THE DRY AIR AT 850 MB
AND BELOW IS PUSHING INTO THE REGION AND CLEARING THE FORECAST
AREA. BY DAYBREAK, IT LOOKS LIKE WE WILL GET MOSTLY SUNNY SKIES,
WITH ONLY THE CIRRUS BLOW OFF FROM THE MCS IN DAKOTAS, WHICH
SHOULD MOVE SOUTHEAST IN THE COMING HOURS, MISSING MICHIGAN.
TONIGHT...THE HIGH WILL TRANSIT THE FORECAST AREA DURING THE DAY,
SO THAT IN THE EVENING, THE RETURN FLOW WILL START IN NW LOWER.
TEMPERATURES THERE SHOULD IN THE 50S, WHILE IN NE LOWER AND E
UPPER THE WINDS WILL DECOUPLE FOR A TIME WHILE THE CORE OF THE
HIGH EXITS AND ALLOW SOME RADIATIONAL COOLING. TEMPERATURES WILL
FALL INTO THE UPPER 40S BEFORE HOLDING FROM THE RETURN FLOW AND
THE INCREASING CLOUDS FROM THE WARM FRONT BEGINNING TO FORM. THE
NAM AND GFS KEEP THE REGION DRY THROUGH 12Z AS THE BETTER
ISENTROPIC FORCING REMAINS UPSTREAM IN THE MINNESOTA ARROWHEAD.
THE ECMWF SEEMS THE OUTLIER WITH THE MOISTURE SOMEWHAT MORE
AGGRESSIVELY MOVING INTO LOWER MICHIGAN BY 12Z. CONSIDERING THAT
ALL THE MODELS HAVE THE SAME BASIC SCENARIO OF THE HIGH MOVING
TOWARD THE SE, AND THAT THE RETURN FLOW FROM A HIGH RETREATING IN
THAT DIRECTION USUALLY TAKES A LITTLE LONGER FOR THE RETURN FLOW
TO PUSH MOISTURE INTO THE STATE, THINK THAT THE GFS/NAM IDEA IS
RIGHT, SO HAVE THE RAIN STAYING OFF TO THE WEST THROUGH 12Z.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 304 AM EDT SUN SEP 8 2013
MONDAY THRU TUESDAY...SURFACE HIGH CENTER WILL SHIFT EAST OF OUR
STATE LATE SUNDAY NIGHT...WITH RETURN MOIST SOUTHERLY FLOW QUICKLY
KICKING IN EARLY MONDAY. A WARM FRONT ASSOCIATED WITH LOW PRESSURE
DEVELOPING IN THE NRN PLAINS WILL LIFT NE INTO NRN MICHIGAN ON
MONDAY. CHANCES OF SHOWERS AND STORMS WILL INCREASE...ESPECIALLY
ACROSS UPR AND FAR NRN LWR MICHIGAN AS DEEP MOISTURE POOLS AROUND
AND NORTH OF THE WARM FRONT. GREATEST CHANCE OF PRECIP WILL DEVELOP
MONDAY NIGHT AS THE SURFACE LOW CENTER TRACKS ALONG THE WARM FRONT
THRU THE STRAITS. THE ASSOCIATED COLD FRONT WILL SLOWLY SLIDE THRU
OUR CWA TUESDAY AND TUESDAY NIGHT. FOCUS OF CONVECTIVE DEVELOPMENT
WILL GENERALLY FOLLOW THIS BOUNDARY... GRADUALLY SHIFTING HIGHEST
POPS FROM ERN UPR AND FAR NRN LWR MICHIGAN ON TUESDAY SOUTHWARD TO
ALL OF NRN LWR MICHIGAN FOR TUESDAY NIGHT. TEMPS WILL RESPOND TO
STRENGTHENING WAA SOUTH OF THE WARM FRONT AND AHEAD OF THE COLD FRONT
BOTH MONDAY AND TUESDAY. HIGH TEMPS MONDAY AFTERNOON WILL WARM WELL
INTO THE 70S ACROSS NRN LWR MICHIGAN SOUTH OF THE WARM FRONT...AND
AROUND 70 ACROSS ERN UPR MICHIGAN WITHIN THICKER CLOUDS AND BETTER
PRECIP CHANCES ALONG THE WARM FRONT. HIGH TEMPS TUESDAY AFTERNOON
WILL VARY GREATLY ACROSS OUR CWA AS THE COOL FRONT SLIDES
THRU...RANGING FROM THE MID TO UPPER 70S IN ERN UPR MICHIGAN TO
AROUND 90 NEAR SAGINAW BAY.
WEDNESDAY THRU SATURDAY...BROAD DEEP CYCLONIC FLOW WILL LINGER ACROSS
THE WRN GREAT LAKES REGION IN THE WAKE OF THE COLD FRONT WEDNESDAY
INTO THURSDAY...AS WILL SOME LIMITED MOISTURE. LOW LEVEL CONVERGENCE
VIA THE CYCLONIC FLOW AND POCKETS OF MOISTURE WILL KEEP SMALL
CHANCES OF SHOWERS IN THE FORECAST THRU THURSDAY. CAA BEHIND THE
FRONT WILL DROP HIGH TEMPS BACK INTO THE 70S ON WEDNESDAY. A
STRONGER COLD FRONT WILL MOVE THRU THE WRN GREAT LAKES ON
THURSDAY...DROPPING TEMPS TO BELOW NORMAL LEVELS FOR THE LAST PART
OF THE WEEK. HIGH TEMPS ON THURSDAY WILL RANGE FROM THE MID 60S IN
ERN UPR MICHIGAN TO THE LOWER 70S IN OUR SE CWA. HIGH TEMPS ON
FRIDAY WILL STRUGGLE TO WARM OUT OF THE 50S ACROSS ERN UPR
MICHIGAN...AND WILL BE MAINLY IN THE LOWER 60S ACROSS NRN LWR
MICHIGAN. LATEST ECMWF IS TRENDING COLDER FOR FRIDAY...DROPPING 850
MB TEMPS TO -2 C ACROSS OUR FAR NRN CWA. COLD CANADIAN SURFACE HIGH
CENTER WILL MOVE OVERHEAD FRIDAY NIGHT/EARLY SATURDAY. THIS COLD
AIRMASS COMBINED WITH CLEARING SKIES AND LIGHT/CALM WINDS WILL
LIKELY RESULT IN SOME PATCHY FROST DEVELOPING LATE FRIDAY NIGHT INTO
EARLY SATURDAY. SATURDAY WILL BE ANOTHER COOL DAY...WITH HIGHS ONLY
IN THE 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 645 AM EDT SUN SEP 8 2013
OVERALL VFR CONDITIONS ARE EXPECTED ACROSS ALL NRN LWR MICHIGAN
TAF SITES THRU EARLY MORNING MORNING AS STRONG COOL CANADIAN HIGH
PRESSURE AND DRY AIR CONTINUE TO BUILD SOUTH INTO MICHIGAN. N/NE
WINDS AOB 10 KTS TODAY WILL BECOME LIGHT AND VARIABLE TONIGHT AS
THE SURFACE HIGH CENTER MOVES OVERHEAD.
&&
.MARINE...
ISSUED AT 304 AM EDT SUN SEP 8 2013
SMALL CRAFT WINDS ARE EXPECTED THROUGH THE MORNING AS THE GRADIENT
WON`T SLACKEN OVER THE LAKES UNTIL THE AFTERNOON. WINDS WILL
CONTINUE TO FALL OFF AS THE HIGH TAKES CONTROL THROUGH TONIGHT.
WINDS AND WAVES WILL INCREASE ON MONDAY AND MONDAY NIGHT AS THE
SFC LOW APPROACHES THE REGION.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LHZ348-
349.
LM...SMALL CRAFT ADVISORY UNTIL 11 AM EDT THIS MORNING FOR LMZ344>346.
LS...NONE.
&&
$$
UPDATE...ARNOTT
SYNOPSIS...JL
SHORT TERM...JL
LONG TERM...MR
AVIATION...MR
MARINE...JL
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
741 AM EDT SUN SEP 8 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 520 AM EDT SUN SEP 8 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE OVER NW CANADA AND
A TROF OVER ERN NAMERICA. STRONG SHORTWAVE DIVING SE TOWARD NEW
ENGLAND HAS RESULTED IN AMPLIFICATION OF THE ERN TROF OVER THE LAST
24HRS. UPSTREAM...MID LEVEL LOW THAT HAS BEEN OVER THE PACIFIC NW
OVER THE LAST FEW DAYS HAS MOVED LITTLE. CENTER IS CURRENTLY OVER
FAR NE WA. DOWNSTREAM OF THIS FEATURE...TAP OF SUBTROPICAL MOISTURE
EXTENDING INTO THE NRN ROCKIES HAS BEEN AIDING CLUSTERS OF SHRA/TSRA
ACROSS WY/MT INTO THE DAKOTAS. CLOSER TO HOME...IN THE WAKE OF THE
SHORTWAVE MOVING TOWARD NEW ENGLAND...SFC HIGH PRES HAS SETTLED OVER
NRN ONTARIO. FEED OF DRIER AIR ASSOCIATED WITH THE HIGH RESULTED IN
LOW CLOUDS/FOG ACROSS PORTIONS OF UPPER MI CLEARING OUT LAST
EVENING. EARLY THIS MORNING...ONLY SOME THIN CI BLOWOFF FROM
CONVECTION WELL TO THE W IS SPILLING INTO THE UPPER LAKES.
FCST AREA TODAY WILL BE UNDER THE INFLUENCE OF HIGH PRES MOVING SE
FROM NORTHERN ONTARIO. CU RULE SUGGESTS SCT CU SHOULD DEVELOP FOR A
TIME THIS MORNING/EARLY AFTN...SIMILAR TO WHAT WAS OBSERVED N/NW OF
LAKE SUPERIOR YESTERDAY. OTHERWISE...WILL PROBABLY CONTINUE TO SEE
SOME MAINLY THIN CI ACROSS THE FCST AREA TODAY. TEMPS WILL BE ON THE
COOL SIDE OF NORMAL DESPITE SUNSHINE. MIXING TO THE INVERSION BASE
ON FCST SOUNDINGS YIELDS HIGH TEMPS NEAR 70 AWAY FROM THE MODERATING
INFLUENCE OF THE GREAT LAKES. THIS LINES UP WELL WITH OBSERVED HIGHS
UPSTREAM YESTERDAY.
TONIGHT...MIDLEVEL LOW CURRENTLY OVER NE WA WILL BEGIN TO OPEN UP
AND DRIFT E INTO MT. WHILE THIS FEATURE WILL STILL BE TOO FAR W TO
BE A FACTOR HERE...MODELS SHOW WEAKER SHORTWAVES LIFTING NE AHEAD OF
THE LOW AND AROUND WEAKENING CNTRL CONUS RIDGE. AS IN RECENT DAYS...
FCST DILEMMA IS WHETHER ANY OF THESE WEAKER SHORTWAVES WILL BE ABLE
TO SPREAD PCPN INTO THE FCST AREA TONIGHT. THE ECMWF CONTINUES TO BE
MOST AGGRESSIVE SPREADING PCPN INTO THE UPPER LAKES. IN FACT...THE
00Z RUN IS MOST AGGRESSIVE AS IT SPREADS PCPN ACROSS THE ENTIRE FCST
AREA TONIGHT. MEANWHILE...OTHER MODELS WHICH HAD SUPPORTED A FASTER
EWD PUSH OF PCPN (UKMET IN PARTICULAR) HAVE BACKED OFF. GIVEN THE
RATHER SHARP ERN TROF...BELIEVE THE ECMWF IS PROBABLY TOO FAST
DRIVING PCPN EWD. 03Z SREF PROBABILITY OF AT LEAST 0.01 INCH OF PCPN
TONIGHT ONLY REACHES AROUND 20PCT OVER THE FAR W. SINCE BULK OF
GUIDANCE PAINTS A SIMILAR PICTURE TO THE SREF...WILL BASICALLY
MAINTAIN FCST CONTINUITY WITH THE LAST SEVERAL FCSTS AND ONLY BRING
SCHC POPS INTO THE W OVERNIGHT. OTHERWISE...SOUTHERLY RETURN FLOW OF
WARMER/MOISTER AIR AND AN INCREASE IN CLOUDS WILL RESULT IN A WARMER
NIGHT MOST AREAS...ESPECIALLY OVER THE W WHERE GRADIENT WILL BE
TIGHTENING FIRST AND WHERE THICKER CLOUDS WILL ARRIVE EARLIEST.
LINGERING DRY AIR MASS IN THE EVENING COMBINED WITH INITIALLY MOSTLY
CLEAR SKIES AND LIGHT WIND OVER THE E MAY ALLOW TEMPS AT TRADITIONAL
INTERIOR COLD SPOTS TO FALL INTO THE LWR 40S. ONE SIDE ISSUE THAT
MAY ARISE TONIGHT IS THE POTENTIAL FOR LOW CLOUDS AND/OR FOG OVER
THE E. IF SOUTHERLY WINDS UP LAKE MICHIGAN INCREASE SUFFICIENTLY...
LOW CLOUDS AND/OR FOG WILL DEVELOP AS HIGHER DWPT AIR OFF THE LAKE
ADVECTS INTO THE CHILLY INTERIOR. WILL BE SOMETHING TO WATCH FOR.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 535 AM EDT SUN SEP 8 2013
AT 12Z MONDAY UPPER MI WILL BE UNDER THE INFLUENCE OF THE 500MB
RIDGE...STRETCHING ACROSS MUCH OF THE S CENTRAL AND SE U.S. OUR EYES
WILL BE ON THE 500MB TROUGH OVER MT/ID/WY...WHICH WILL SUPPRESS THE
RIDGE TO OUR S AS THE TROUGH PUSHES TOWARD THE UPPER GREAT LAKES.
WARM FRONT WILL SURGE TO OUR N MONDAY MORNING...BEING THE FOCUS OF
SHRA/TSRA DURING THE DAY. THERE REMAINS SOME SIGNIFICANT
DISCREPANCIES ON THE TIMING WHEN COMPARING AVAILABLE MODELS. WHILE
THE NAM/GFS/CANADIAN MODELS KEEP BASICALLY ALL OF THE LAND
/EXCLUDING THE KEWEENAW PENINSULA/ DRY ON MONDAY...THE GENERALLY
FAVORED ECMWF HAS A SOLID 0.25IN OR MORE OVER THE ENTIRE LAND. HAVE
CONTINUED TO UTILIZE A MODEL CONSENSUS APPROACH...WHICH LEADS TO
AROUND 0.5 TO 1IN OF QPF FROM LATE TONIGHT THROUGH TUESDAY OVER THE
KEWEENAW PENINSULA...AND E AREAS N OF A LINE FROM MUNISING THROUGH
NEWBERRY. EXPECT MUCH OF THE STRONGER STORMS TO FOLLOW THE COLD
FRONT FARTHER TO OUR S...WITH LIGHTNING AND HEAVY RAIN BEING THE
MAIN THREATS FOR OUR CWA. AS FOR NON-PRECIP TALK...THE WAA WILL
RESULT IN A WARM NIGHT MONDAY NIGHT...APPROX 15F ABOVE NORMAL FOR
THIS TIME OF YEAR. THIS WILL BE THANKS TO WARM S WINDS REAMING UP
THROUGH THE NIGHT.
IT LOOKS TO BE A VERY ACTIVE AT 500MB FROM TUESDAY MORNING THROUGH
THE END OF THE WORK WEEK. THE INITIAL KICKER OF A SHORTWAVE WILL
PUSH W TO E ACROSS THE CWA TUESDAY AS THE SFC LOW EXITS E LAKE
SUPERIOR INTO SE QUEBEC. THIS WILL TIME OUT WITH THE RIGHT REAR
QUADRANT OF THE 250MB JET.
ALTHOUGH NOT A THREAT OF THUNDERSTORMS WILL BE DONE AFTER TUESDAY
AFTERNOON...THE EXTENDED SECTION OF THE FCST IS NOT WITHOUT
SIGNIFICANCE. LOOK FOR THE NEXT 500MB TROUGH TO SWING THROUGH MID
WEEK. WHILE NOT A SIGNIFICANT RAIN MAKER...IT WILL MARK THE START OF
SIGNIFICANTLY COOLER WEATHER. NW TO N WINDS WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT...WITH LINGERING LOW LEVEL MOISTURE. KEPT SLIGHT
CHANCE-CHANCE POPS NEAR LAKE SUPERIOR AS 850MB TEMPS FALL TO AROUND
-2C BY DAYBREAK FRIDAY. HIGHS IN THE 60S...AND EVEN UPPER 50S LOOK
REASONABLE FOR BOTH THURSDAY AND FRIDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 740 AM EDT SUN SEP 8 2013
WITH ONE EXCEPTION...HIGH PRES MOVING SE THRU THE UPPER GREAT LAKES
WILL PROVIDE VFR CONDITIONS AT KIWD/KCMX/KSAW THRU THIS FCST PERIOD.
THAT ONE EXCEPTION IS THE POSSIBILITY OF A LOW MVFR OR IFR/LIFR
CLOUD DECK AT KCMX/KSAW FOR A COUPLE OF HRS THIS MORNING AS WINDS
ARE CURRENTLY VEERING AROUND MORE EASTERLY ACROSS LAKE SUPERIOR.
THIS IS RESULTING IN SLIGHTLY HIGHER DWPT MARINE LAYER AIR UPSLOPING
OFF THE LAKE INTO COOLER AIR INLAND. ONLY OTHER CONCERN FOR THIS
FCST PERIOD IS THE POSSIBILITY OF MARGINAL LLWS TONIGHT AT KIWD AND
POSSIBLY KCMX AS WINDS INCREASE ABOVE NOCTURNAL INVERSION IN
RESPONSE TO GRADIENT TIGHTENING BTWN DEPARTING SFC HIGH PRES AND LOW
PRES OVER THE WRN PLAINS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 535 AM EDT SUN SEP 8 2013
HIGH PRES OVER NRN ONTARIO WILL DRIFT SE TODAY. JUST AHEAD OF THE
HIGH...EXPECT A BRIEF PUSH OF STRONGER WINDS (GUSTS TO 20-25KT) OVER
MUCH OF LAKE SUPERIOR EARLY THIS MORNING. COASTAL CONVERGENCE OVER
FAR WRN LAKE SUPERIOR AND PERHAPS BTWN THE HURON ISLANDS AND THE
KEWEENAW MAY STILL LEAD TO SOME GUSTS OVER 20KT LOCALLY THRU THE
AFTN. OTHERWISE...WINDS WILL SETTLE DOWN A BIT FOR THE AFTN...
ESPECIALLY OVER THE E...CLOSER TO SFC HIGH PRES CENTER. AS THE HIGH
MOVES AWAY FROM THE UPPER LAKES TONIGHT...GRADIENT SHOULD REMAIN
WEAK ENOUGH TO KEEP WINDS UNDER 20KT.
ANOTHER PERIOD OF STRONGER WINDS WILL BE POSSIBLE THURSDAY INTO
THURSDAY EVENING...WITH N-NW GUSTS OF 25-30KTS OVER MAINLY CENTRAL AND E
LAKE SUPERIOR...AS STRONG HIGH PRESSURE NEARS FROM S CENTRAL
CANADA AND LOW PRESSURE EXITS ACROSS QUEBEC.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...KF
AVIATION...ROLFSON
MARINE...KF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
643 AM CDT SUN SEP 8 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 359 AM CDT SUN SEP 8 2013
THUNDERSTORMS IN PROGRESS EARLY THIS MORNING OVER THE DAKOTAS ARE
BEING AIDED BY LOW LEVEL MOISTURE TRANSPORT FROM THE SOUTHEAST...MID
LEVEL FRONTOGENESIS AND A COUPLED JET ALOFT OVER THE NORTHERN
PLAINS. THIS PATTERN WILL SHIFT SLOWLY EASTWARD TODAY. THIS WILL
LIKELY ALLOW SOME OF THE SHOWERS AND ISOLATED THUNDERSTORMS TO REACH
INTO CENTRAL MN. HOWEVER...A WEAKENING TREND SHOULD DEVELOP AS THE
ACTIVITY OUTRUNS THE LOW LEVEL MOISTURE TRANSPORT AND INSTABILITY
GRADIENT. THE 00Z CAMS FAILED ON DEVELOPING THIS CONVECTION AND
REALLY DON/T HAVE A CLUE ON WHAT IS OCCURRING ATTM. AN EXCEPTION IS
THE HRRR...WITH HOURLY UPDATES...WHICH SHOWS THE POTENTIAL FOR
SHOWERS TO PROGRESS ALL THE WAY TO KEAU BY THE MIDDLE OF THE
AFTERNOON. FOR NOW...ALLOWED SHOWER AND ISOLATED THUNDERSTORM
ACTIVITY TO REACH THE TWIN CITIES BY EARLY THIS AFTERNOON BEFORE
GOING INTO A HOLDING PATTERN. IN ADDITION...EXTENSIVE LOW
CLOUDINESS HAS FORMED ONCE AGAIN OVERNIGHT ACROSS SOUTHERN WI AT
THE BASE OF HIGH PRESSURE OVER LAKE SUPERIOR. THIS CLOUDINESS IS
STREAMING WESTWARD AND WILL OVERTAKE EAST CENTRAL AND SOUTH
CENTRAL MN BY DAYBREAK. THIS COUPLED WITH CLOUDINESS ASSOCIATED
WITH THE SHOWER ACTIVITY TO THE WEST WILL RESULT IN A PARTLY TO
MOSTLY CLOUDY DAY ACROSS THE FA. HIGHS REMAIN ON TRACK WITH UPPER
70S TO LOWER 80S.
A LOW LEVEL JET IS PROGGED TO INCREASE TO OVER 60 KNOTS TONIGHT
ACROSS THE EASTERN DAKOTAS IN ADVANCE OF A LOW PRESSURE SYSTEM
DEVELOPING OVER THE WESTERN HIGH PLAINS. EVERYTHING CONTINUES TO
POINT TO A CONVECTIVE COMPLEX DEVELOPING OVER THE EASTERN DAKOTAS
AND ADVANCING ENE INTO NORTHERN MN BY DAYBREAK MONDAY. THE MAIN
CONCERN FOR THE FA IS HOW FAR SOUTH THUNDERSTORM DEVELOPMENT WILL
OCCUR. THE ARW AND NMM WRF APPEAR TO DEVELOP CONVECTION TO FAR SOUTH
INTO SOUTHERN MN BASED ON RECENT PERFORMANCE. THE SPC WRF HAS
CONVECTION DEVELOPING ALONG AND NORTH THE I-94 CORRIDOR WHICH AGREES
MORE WITH OUR THINKING HERE THE PAST FEW NIGHTS BASED ON THE LOW
LEVEL WAA AND MID LEVEL FRONTOGENETIC PATTERN. THIS ALSO GOES ALONG
WITH THE UPGLIDE/ADIABATIC OMEGA PATTERN SEEN ON THE 310/315K THETA
SURFACES. THEREFORE...CONTINUED WITH CHANCE POPS ACROSS ABOUT THE
NORTHERN HALF OF THE CWA TONIGHT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 359 AM CDT SUN SEP 8 2013
MODELS IN GOOD AGREEMENT ON EVOLUTION OF THE UPPER AIR PATTERN
THROUGH THE WORK WEEK...WITH A POSITIVELY TILTED TROUGH WORKING
ACROSS THE UPPER MS VALLEY MONDAY THROUGH TUESDAY. FOR THE SECOND
HALF OF THE WEEK...ANOTHER HIGHLY AMPLIFIED WRN RIDGE ERN TROUGH
PATTERN WILL SET IN...WITH COOLER AND DRY NW FLOW RETURNING. BY THE
WEEKEND... THIS RIDGE LOOKS TO FLATTEN OUT AS IT PUSHES EAST INTO
THE PLAINS. IN ADDITION...ANOTHER WAVE LOOKS TO BE TOPPING THE RIDGE
THIS WEEKEND...WITH THE NEXT CHANCE FOR RAIN RETURNING THEN.
ALL SIGNS CONTINUE TO POINT TO NEAR RECORD HEAT TO START THIS PERIOD
ON MONDAY. BY 7PM MONDAY...MODELS SHOW A SFC LOW LOCATED BETWEEN THE
TWIN CITIES AND DULUTH...WITH A COLD FRONT TRAILING TO THE SW TO
NEAR THE SD/MN/IA BORDER. THIS PUTS SRN/ERN MN INTO WRN WI IN THE
HEART OF AN IMPRESSIVE WARM NOSE...WITH THE GFS AND ECMWF SHOWING
925 MB TEMPS BETWEEN 30 AND 32 C...WHICH SUPPORT HIGHS MAKING A RUN
FOR 100 WITHIN THE WARM SECTOR. BACK TRACKING THIS WARM PLUME FROM
MONDAY AFTERNOON TO WHERE MODELS INITIALIZED IT AT 00Z SHOWS THE AIR
FOR MONDAY ORIGINATING FROM THE CO/KS/NEB REGION...WHERE SATURDAY
AFTERNOON HIGHS WERE ALL A COUPLE OF DEGREES ON EITHER SIDE OF 100.
THEREFORE...MAINTAINED CURRENT FORECAST HIGHS...EVEN INCREASING THEM
A NUDGE. AS FOR RECORDS...THEY ARE TOUGH TO ATTAIN BETWEEN SEPTEMBER
8TH AND 11TH...AS THIS FOUR DAY STRETCH CORRESPONDS TO WHAT IS STILL
THE HEAT WAVE OF RECORD FOR SEPTEMBER FROM BACK IN 1931...BUT WE
WILL STILL BE VERY CLOSE COME MONDAY.
OF COURSE THERE IS A POTENTIAL TROUBLE MAKER LURKING IN THE SHADOWS
FOR MONDAY...AND THAT IS THE POTENTIAL FOR THUNDERSTORMS SUNDAY
NIGHT INTO MONDAY MORNING AND ANY CLOUD COVER THEY LEAVE BEHIND. THE
MOST EXTREME EXAMPLE OF THIS WOULD BE THE HIRES-ARW...WHICH HAS
HIGHS IN THE UPPER 90S IN SOUTH CENTRAL MINNESOTA...BUT ONLY HAS A
HIGH OF 83 /16 DEGREES COOLER THAN WHAT WE A CURRENTLY GOING WITH!/
THANKS TO THE MCS IT BRINGS DOWN I-94 MONDAY MORNING. HOWEVER...AS
STATED IN THE SHORT TERM...THE HIRES MODELS LOOK BE TOO FAR SOUTH
WITH ACTIVITY SUNDAY NIGHT. INSTEAD...WILL CONTINUE TO FOLLOW THE
IDEAS OF THE DETERMINISTIC MODELS WITH MAJORITY OF ACTIVITY
FOLLOWING THE FORCING ACROSS NRN MN...LEAVING THE MPX AREA MAINLY
DRY.
WITH THE CURRENT FORECAST...THERE CONTINUES TO BE FIRE WEATHER
CONCERNS...SEE FIRE WEATHER SECTION FOR MORE ON THAT.
UNFORTUNATELY...WE LOOK TO FURTHER BAKE THE LANDSCAPE MONDAY...BUT
NOT GIVE IT MUCH OF A DRINK AS THE COLD FRONT SWINGS THROUGH MONDAY
NIGHT INTO TUESDAY MORNING. DID CUT BACK ON POPS IN THIS
PERIOD...CAPPING THEM IN THE 30S AS ONLY SCATTERED CONVECTION IS
EXPECTED MAINLY BEHIND THE FRONT AS PROGRESSIVE HEIGHT FALLS FINALLY
HELP BREAK DOWN THE CAP ENOUGH TO GENERATE CONVECTION LATE MONDAY.
GIVEN DEEP...WELL MIXED INVERTED-V SOUNDINGS EXPECTED ON
MONDAY...ANY STRONGER CONVECTION WILL POSE A WIND THREAT.
TUESDAY AND WEDNESDAY WILL STILL SEE HIGHS IN THE UPPER 70S TO LOWER
80S /ABOUT 5 DEGREES ABOVE NORMAL/...BUT THE ARRIVAL A LARGE DOME OF
HIGH PRESSURE FROM CANADA ON THURSDAY WILL BRING WITH IT MORE FALL
LIKE WEATHER TO END THE WEEK. OF COURSE HIGHS FROM CANADA DO NOT
BRING WHAT WE COULD REALLY USE AT THE MOMENT...RAINFALL...WITH IT
LOOKING DRY FROM TUESDAY AFTERNOON TROUGH THE REST OF THE WORK WEEK.
NEXT WEEKEND...THE GFS/ECMWF CONTINUE TO SHOW A SHORTWAVE TOPPING
THE RIDGE AND WORKING ACROSS THE NORTH CENTRAL CONUS. WE BEGIN TO
SEE MOISTURE RETURN ON SATURDAY...WITH AT LEAST SOME HOPE FOR SOME
RAINFALL OVER THE WEEKEND. HAVE SEEN THE MODELS SLOW THIS MOISTURE
RETURN SOME...BUT THERE IS STILL HOPE FOR SOME RAIN SATURDAY INTO
SUNDAY...THOUGH STILL PLENTY OF TIME FOR THE MODELS TO FIGURE OUT A
WAY TO SEND THIS PRECIP ACROSS NRN MN.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 630 AM CDT SUN SEP 8 2013
TWO ISSUES TO DEAL WITH THIS MORNING. FIRST...AN AREA OF MVFR
CEILINGS BETWEEN 010-020... THAT DEVELOPED ACROSS SOUTHERN WI DURING
THE EVENING... HAS SPREAD WESTWARD INTO SOUTHERN MN AND WEST CENTRAL
WI. THE RAP 0.5KM CPD HAS HAD AN EXCELLENT HANDLE ON THIS. IT
SUGGESTS THESE CEILINGS WILL SPREAD ACROSS KRWF AND KSTC EARLY
THIS MORNING AND PERHAPS REACH KAXN BY 15Z. THE BAND OF LOW
CEILINGS THEN DISSIPATES DURING THE EARLY AFTERNOON. THE BACK EDGE
OF THIS CLOUDINESS HAS CLEARED KEAU AND WILL BE CLEARING KRNH IN
AN HOUR OR TWO. THE SECOND ISSUE TODAY IS THE THREAT FOR SHOWERS
AND ISOLATED THUNDERSTORMS DEVELOPING AHEAD OF AN MCV NORTH OF
KABR. THIS CIRCULATION WAS BORN OUT OF COMPLEX OF STORMS THAT
DEVELOPED TO THE WEST EARLIER IN THE NIGHT. ALTHOUGH THIS
CIRCULATION IS MOVING AWAY FROM THE BEST LOW LEVEL MOISTURE FEED
AND INSTABILITY GRADIENT... SHOWERS AND A FEW THUNDERSTORM HAVE
ALREADY REACHED KAXN. THE CAMS HAVE NOT HANDLED THIS WELL AT ALL
WITH ONLY THE HRRR SHOWING A CONTINUED DOWNWARD TREND TO THE
ACTIVITY AS IT MOVES ACROSS CENTRAL MN THIS MORNING AND INTO WEST
CENTRAL WI THIS AFTERNOON. THEREFORE... VCSH/VCTS IN AT THE MN TAF
SITES THIS THIS MORNING.
TONIGHT POSES ANOTHER PROBLEM AS A WARM FRONT LIFTS NORTHWARD
ACROSS THE TAF SITES. METEOROLOGICAL REASONING WOULD SUGGEST MOST
OF THE SHOWERS AND THUNDERSTORMS THAT DO DEVELOP WOULD OCCUR
ACROSS CENTRAL MN AND WEST CENTRAL WI. CERTAINLY NOT WHAT THE CAMS
INDICATE WITH ACTIVITY SPREAD CLEAR SOUTH TO THE IA BORDER. KEPT
THE MENTION TO VCSH AT THIS POINT DUE TO THE UNCERTAINTY OF NOT
ONLY THE LOCATION BUT AS TO WHETHER OR NOT ANYTHING OCCURS. IT MAY
END UP WELL TO THE NORTH OF US. THERE IS ALSO AN INDICATION THAT
MORE MVFR CEILINGS WILL DEVELOP THIS EVENING ACROSS SOUTHERN WI
AND SPREAD INTO EASTERN MN AND WESTERN WI DURING THE NIGHT.
CONFIDENCE IS NOT HIGH BUT INDICATE SOME SCT015-20 FOR NOW.
KMSP...
MVFR CEILINGS GRADUALLY LIFTING AND BREAKING UP THIS MORNING. THE
BACK EDGE IS CURRENTLY ABOUT 30 MILES SE OF THE AIRFIELD. SOME
VFR SHOWERS ARE EXPECTED AROUND NOON AND THROUGH A FEW HOURS OF
THE AFTERNOON. MAINLY DRY TONIGHT BUT AN ISOLATED SHRA/TSRA CAN
NOT BE RULE OUT BETWEEN 06Z-12Z. MORE NUMEROUS ACTIVITY SHOULD BE
WELL TO THE NORTH AND EAST OF THE AIRFIELD. A REPEAT OF THE MVFR
CEILINGS MAY OCCUR TONIGHT. CONFIDENCE IS NOT HIGH AT THIS
POINT... BUT NEWER DATA THIS MORNING SUGGESTS THE POSSIBILITY BY
04Z AND LASTING TO NEAR DAYBREAK. EASTERLY WINDS NEAR 10 KNOTS
TODAY AND THEN SE TONIGHT AND EARLY MONDAY.
/OUTLOOK FOR KMSP/
MON NGT...VFR. CHC MVFR/TRW. W WINDS 10 KTS.
TUE...VFR. CHC RW EARLY. W WINDS 5-10 KTS.
WED...VFR. NW WINDS 10 KTS.
&&
.FIRE WEATHER...
ISSUED AT 359 AM CDT SUN SEP 8 2013
CURRENT FORECAST CONTINUES TO POINT TOWARD A POTENTIALLY SEVERE
FIRE WEATHER DANGER DAY ON MONDAY...ESPECIALLY FROM SOUTHERN INTO
EAST CENTRAL MN. HIGH TEMPERATURES IN THE AREA OF CONCERN WILL
WARM INTO THE UPPER 90S...WHILE DEW POINTS LOWER INTO THE MID 50S.
THIS SCENARIO WOULD YIELD MINIMUM RELATIVE HUMIDITY VALUES NEARING
25 PERCENT ON MONDAY AFTERNOON...WHEN SOUTHERLY WINDS WILL ALSO BE
ON THE BREEZY SIDE AT SPEEDS OF 15 TO 20 MPH. WHILE VEGETATION IS
STILL RATHER GREEN...THE PRECIPITATION DEFICITS OVER THE LAST
MONTH AND THE MOUNTING DROUGHT CONDITIONS ARE OF NOTABLE CONCERN.
MAIN SOURCE OF UNCERTAINTY FOR THIS FORECAST IS THE POTENTIAL FOR
THUNDERSTORMS INTO MONDAY MORNING...WITH RESULTANT CLOUD COVER
RESTRICTING HIGHS A BIT MORE THAN FORECAST FOR EASTERN MN INTO
WI...THOUGH HIGHEST PROBABILITY FOR THUNDERSTORMS SUNDAY NIGHT
INTO MONDAY REMAIN NORTH OF THE MPX AREA.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...RAH
LONG TERM...MPG
AVIATION...RAH
FIRE WEATHER...MPG
AREA FORECAST DISCUSSION
NWS HASTINGS NE
937 AM CDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 936 AM CDT SUN SEP 8 2013
FCST HAS BEEN UPDATED TO LOWER HIGHS WHERE FOG IS INHIBITING
HEATING /ALONG AND N OF I-80/ AND WHERE THE APPROACHING OUTFLOW
MAY ALSO KEEP TEMPS DOWN. ALSO LOWERED DWPTS PER REASONING FROM
THE PRVS UPDATE. WIND DIRECTION HAS BEEN ADJUSTED THRU MIDDAY TO
ALLOW FOR WIND SHIFT TO NE BEHIND THE BOUNDARY.
UPDATE ISSUED AT 908 AM CDT SUN SEP 8 2013
THE DENSE FOG ADVY HAS BEEN EXTENDED ONE MORE HOUR PER WEBCAMS...
AIRPORT VSBYS AND VIS SATELLITE. USING CONDITIONAL CLIMATOLOGY
/LOOKING BACK AT PAST SIMILAR EVENTS DURING AUG-SEP/ THE
PROBABILITY OF IFR CIG/VSBY CONTS VERY HIGH /81 PERCENT/ THRU 14Z
AND THEN DROPS TO 62 PERCENT 15Z AND 38 PERCENT BY 16Z.
SATELLITE SHOWS A DRY OUTFLOW BOUNDARY FROM OVERNGT TSTMS
APPROACHING NEB HWY 92. THIS WILL SHIFT WINDS TO NE AS ALREADY
SEEN AT ODX/BVN. THIS WILL COMPLICATE THE FCST HIGHS TODAY AND
DEPENDING ON ITS DENSITY IT MAY PREVENT THE E-W TROF FROM LIFTING
BACK N.
MRNG DATA DIAGNOSIS IS STILL ON-GOING...BUT ENVISION DWPTS WILL
NEED TO BE LOWERED SUBSTANTIALLY S AND W OF THE TRI-CITIES. HIGH
TEMPS IN THE 100S VIRTUALLY GUARANTEES MIN RH DROPPING INTO THE
TEENS THIS AFTN.
MORE LATER...
UPDATE ISSUED AT 706 AM CDT SUN SEP 8 2013
WITHIN THE PAST HOUR...DENSE FOG HAS EXPANDED IN COVERAGE EASTWARD
ACROSS MOST COUNTIES MAINLY ALONG/NORTH OF THE INTERSTATE 80
CORRIDOR PER AUTOMATED AIRPORT OBS AND WEBCAMS...WHILE
MAINTAINING INTENSITY FARTHER SOUTHWEST INTO THE HOLDREGE AREA AS
WELL. AS A RESULT...HAVE ADDED SEVERAL MORE COUNTIES TO THE DENSE
FOG ADVISORY...WHICH NOW INCLUDES GENERALLY ALL AREAS NORTH OF AN
ELWOOD-HASTINGS-YORK LINE. THE LATEST HRRR VISIBILITY PRODUCT HAS
CAPTURED THE AREA OF DENSE FOG FAIRLY WELL...AND SUGGESTS MOST OF
IT SHOULD LIFT/IMPROVE CONSIDERABLY BY 9 AM OR SO...BUT COULD
MAYBE LINGER CLOSER TO 10 AM IN THE CORE OF THE FOG AREA. INCOMING
DAY SHIFT WILL MONITOR TRENDS AND ADJUST HEADLINE AS NECESSARY.
UPDATE ISSUED AT 546 AM CDT SUN SEP 8 2013
WENT AHEAD WITH A DENSE FOG ADVISORY FOR A FEW HOURS THIS MORNING
FOR AREAS GENERALLY WEST OF HIGHWAY 281 AND ALONG THE INTERSTATE
80 CORRIDOR WHERE VSBY AVERAGE ONE QUARTER MILE OR LESS. VSBYS
WILL IMPROVE AFTER SUNRISE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 453 AM CDT SUN SEP 8 2013
AN UPPER LEVEL RIDGE OF HIGH PRESSURE CONTINUES TO DOMINATE THE
WEATHER PATTERN ACROSS THE INTERIOR CONUS...RESULTING IN HOT
TEMPERATURES FOR EARLY SEPTEMBER...WELL ABOVE NORMAL. AT THE
SURFACE...LOW PRESSURE WAS CENTERED ALONG THE WY/NEB BORDER...WITH
A STALLED FRONTAL BOUNDARY EXTENDING EASTWARD ALONG THE NEB/KS
STATELINE. HIGH DPS IN THE UPPER 60S TO AROUND 70 HAVE POOLED NORTH
OF THE BOUNDARY AND IN PRESENCE OF THE LLVL MOISTURE...SOME PATCHY
FOG HAS DEVELOPED WITH THE LOWEST VSBYS SO FAR AROUND ONE OR TWO
MILES. WILL CONTINUE TO MONITOR VSBY TRENDS THRU THE PRE DAWN
HOURS AS MODELS ARE NOT IN AGREEMENT ON HOW SIGNIFICANT FOG WILL BE
...AND THE HRRR SUGGESTS POTENTIAL FOR DENSE FOG.
THE FRONTAL BOUNDARY ALONG THE NEB/KS STATELINE WILL LIFT NORTH AS A
WARM FRONT TODAY AND TEMPERATURES WILL BE TOASTY WITH READINGS
RISING WELL INTO THE 90S...AND OUR WESTERN/SOUTHERN ZONES WILL BE
EVEN WARMER WITH HIGHS IN THE 100 TO 105F RANGE. HEAT INDICES WILL
BE FAIRLY CLOSE OR JUST BELOW AMBIENT TEMPS AS DPS LOWER BEHIND
BOUNDARY...AND SHOULD REMAIN SHY OF HEAT ADVISORY CRITERIA.
CANNOT COMPLETELY RULE OUT THE POTENTIAL FOR AN ISOLATED
THUNDERSTORM THIS AFTERNOON/EVENING...GENERALLY NORTH OF INTERSTATE
80 AS THE WARM FRONTAL BOUNDARY LIFTS ACROSS. MODELS INDICATE
PRESENCE OF MID LEVEL WAA AND FRONTOGENESIS BETWEEN H85 AND H7 NORTH
OF I-80 AND DAYTIME HIGHS ARE RIGHT AROUND CONVECTIVE TEMPERATURES.
BOTH THE NAM/GFS INDICATE THE LIFT/FORCING...BUT ONLY THE 4KM SPC
WRF INDICATES DEVELOPMENT. THE CONVECTIVE POTENTIAL IS LIMITED WITH
CAPPING/WARM MID LEVEL TEMPS...BUT CANNOT RULE OUT AN ISOLATED CHC
AND HAVE ADDED SMALL POPS.
DRY AND MILD CONDITIONS ARE FORECAST LATE EVENING ON...WITH LOWS
AVERAGING IN THE UPPER 60S TO AROUND 70F.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 453 AM CDT SUN SEP 8 2013
THERE CONTINUES TO REMAIN A FAIRLY CONSISTENT FORECAST THEME
THROUGH THESE 6 DAYS...WITH MONDAY FEATURING THE FINALE OF A
MEMORABLE EARLY SEPTEMBER HOT SPELL...ALTHOUGH TUESDAY STILL LOOKS
PLENTY TOASTY AS WELL ACROSS ROUGHLY THE SOUTHEASTERN 1/3 OF THE
CWA WITH HIGHS BETWEEN 90-95. THEREAFTER...THE WED-SAT TIME FRAME
IS EXPECTED TO FEATURE HIGHS PREDOMINANTLY IN THE 80S...WHICH ON
SEVERAL DAYS WILL STILL BE A FEW DEGREES ABOVE NORMAL DESPITE
BEING MORE SEASONABLE. AS FOR SHOWER/THUNDERSTORM CHANCES...THERE
REMAINS AT LEAST A SLIGHT CHANCE MENTION IN THE FORECAST FOR AT
LEAST A PORTION OF THE OUTLOOK AREA DURING EVERY PERIOD FROM
MONDAY NIGHT THROUGH FRIDAY NIGHT...WITH SATURDAY VOID OF
MENTIONABLE POPS...AT LEAST FOR NOW. IF ANYTHING...UNCERTAINTY
CONTINUES TO GROW REGARDING WHICH OF THESE PERIODS MIGHT BE
FAVORED FOR MORE WIDESPREAD PRECIPITATION COVERAGE...SO FOR NOW
MOST OF THESE CHANCES CONTINUE TO BE HELD DOWN IN THE 20-30
PERCENT RANGE. AS DISCUSSED OVER THE PAST 24 HOURS...MONDAY COULD
POTENTIALLY FEATURE SOME OF THE HIGHEST FIRE DANGER THE LOCAL AREA
HAS SEEN THIS SUMMER...AND THESE CONCERNS ARE OUTLINED IN GREATER
DETAIL IN THE SEPARATE FIRE WEATHER SECTION BELOW.
STARTING WITH MONDAY/MONDAY NIGHT...THE LATEST 00Z/06Z MODELS ARE
IN GOOD AGREEMENT ON THE BIG PICTURE ALOFT...WITH THE LOCAL AREA
EXPERIENCING SOUTHWESTERLY FLOW ALOFT AS THE CENTER OF THE
EXPANSIVE RIDGE AXIS CURRENTLY PARKED OVERHEAD CONTINUES TO DRIFT
FARTHER AWAY INTO THE SOUTHEAST STATES...AS A PROGRESSIVE
SHORTWAVE TROUGH TRANSLATES ALONG THE U.S./CANADA BORDER FROM A
CENTRAL POSITION OVER NORTHERN MT AT SUNRISE MONDAY...TO NORTHERN
MN BY SUNRISE TUESDAY. IN RESPONSE...A MODEST COLD FRONT WILL
DRIFT SOUTHEASTWARD INTO THE CENTRAL PLAINS. DURING THE DAYTIME
MONDAY...THE CWA WILL REMAIN JUST AHEAD OF THIS COLD FRONT...WHICH
IS FORECAST TO ALIGN FROM NORTHEAST TO TO NORTH CENTRAL NEB BY
LATE AFTERNOON...BEFORE SLOWLY INFILTRATING MUCH OF THE
NORTHERN/CENTRAL CWA MONDAY NIGHT. THE DAYTIME HOURS SHOULD BE
ANOTHER HOT ONE AREA-WIDE...AS SUSTAINED SOUTH-SOUTHWEST WINDS
PICK UP TO AT LEAST 15-20 MPH WITH GUSTS 25+ MPH IN MOST
AREAS...EXCEPT FOR A BIT LIGHTER SPEEDS POSSIBLE IN FAR NORTHWEST
COUNTIES IN CLOSET PROXIMITY TO THE APPROACHING TROUGH AXIS. WITH
DEEP MIXING FORECAST TO AVERAGE UP TO AROUND 750 MILLIBARS OVER
MUCH OF THE CWA...ANTICIPATE DEWPOINTS TO FALL WELL DOWN INTO THE
50S DURING THE AFTERNOON...WITH 40S IN SEVERAL SOUTHWESTERN
COUNTIES. IN THEORY...THIS SETUP SHOULD SET THE STAGE FOR SOME OF
THE HOTTEST READINGS OF THIS ENTIRE HOT STRETCH...ESPECIALLY IN
CENTRAL/NORTHEAST COUNTIES...BUT SOMEWHAT ODDLY MET/MAV GUIDANCE
SUGGESTS HIGHS MONDAY WOULD BE A TOUCH COOLER THAN THOSE TODAY.
DESPITE THIS...HAVE KEPT FORECAST HIGHS AT LEAST A FEW DEGREES
ABOVE A GUIDANCE BLEND IN MOST AREAS...WITH ALL BUT THE FAR
NORTHERN CWA AIMED TO TOP OUT SOMEWHERE IN THE 98-103 RANGE...WITH
THE HIGHER END OF THIS RANGE IN FAR SOUTHERN/SOUTHWEST COUNTIES.
DUE TO THE LOWER DEWPOINTS...HEAT INDEX VALUES IN MOST AREAS ONLY
AVERAGE 95-100 DEGREES. AS FOR STORM CHANCES...MODELS VARY ON HOW
AGGRESSIVELY CONVECTION MAY TRY TO SLIP INTO OUR FAR NORTHWEST
ZONES MONDAY EVENING/NIGHT...WITH SOME BRINGING THEM JUST IN WHILE
OTHERS KEEP THEM JUST OUTSIDE. GIVEN THE SLOWING NATURE OF THE
SURFACE FRONT...HAVE BACKED OFF MON NIGHT POPS TO ONLY ABOUT THE
NORTHWESTERN 1/4 OF THE CWA...WHILE THE VAST MAJORITY OF THE CWA
STAYS DRY. ALTHOUGH ANY MARGINAL SEVERE THREAT DURING THE LATE
AFTERNOON/EVENING SHOULD LARGELY TARGET THE SANDHILLS REGION JUST
TO OUR NORTHWEST...SUPPOSE A STRONG TO MARGINALLY SEVERE STORM OR
TWO CANNOT BE RULED OUT SLIPPING INTO OUR AREA...WITH THE MAIN
THREAT BEING GUSTY WINDS DUE TO HIGH CLOUD BASES IN THE DEEPLY-
MIXED AIRMASS NEAR THE FRONT. SEVERE PARAMETERS ARE NOT ALL THAT
IMPRESSIVE...WITH THE GFS SUGGESTING EARLY EVENING CAPE AVERAGING
WELL UNDER 1000 J/KG...ALTHOUGH DEEP LAYER SHEAR ISN/T ALL THAT
POOR AROUND 30-40 KNOTS.
TUESDAY/TUES NIGHT...THE NORTHERN MN SHORTWAVE TROUGH QUICKLY
SLIDES EAST INTO SOUTHEAST CANADA...AND ALTHOUGH THE CWA SEES A
PERIOD OF DECENT UPPER JET ENTRANCE REGION LIFT AND ASSOCIATED MID
LEVEL FRONTOGENESIS...THE MAIN FORCING STEADILY SLIDES AWAY TO THE
NORTHEAST...ALLOWING THE SURFACE FRONT TO LOSE STEAM AND GENERALLY
STALL OUT WITHIN OR NEAR THE SOUTHERN EDGE OF THE CWA BY TUESDAY
AFTERNOON/NIGHT. THERE COULD BE A DECENT TEMP GRADIENT IN HIGHS
TUESDAY AFTERNOON...AND HAVE MADE LITTLE CHANGE...STILL AIMING FOR
LOW-MID 80S NORTHWEST TO LOW-MID 90S SOUTHEAST. IF ENOUGH
INSTABILITY BUILDS ALONG THE SURFACE BOUNDARY...COULD MAYBE SEE
SOME STRONG TO SEVERE NEAR-SURFACE BASED STORMS FLARE UP IN
SOUTHERN COUNTIES TUESDAY AFTERNOON/EVENING...WITH MORE ELEVATED
ACTIVITY DEVELOPING FARTHER NORTH AS THE NIGHT WEARS ON IN RESPONSE
TO MID-LEVEL THETA-E ADVECTION. EVEN ONLY 3 DAYS
AWAY...UNCERTAINTY IS VERY HIGH HERE...AND HAVE KEPT DAYTIME POPS
IN SLIGHT CHANCE RANGE...WITH A GREATER COVERAGE OF 30 POPS
TUESDAY NIGHT.
WEDNESDAY THROUGH FRIDAY NIGHT...THERE CONTINUES MULTIPLE...MAINLY
20-30 PERCENT POPS ACROSS ALL/MOST OF THE CWA...AND OBVIOUSLY A
LOT OF FINE-TUNING WILL NEED DONE HERE IN THE COMING DAYS. ON THE
LARGE SCALE ALOFT...THE LOCAL AREA SETS UP UNDER FAIRLY WEAK WEST-
SOUTHWEST FLOW ALOFT...IN THE WAKE OF A DEEPENING TROUGH MIGRATING
ACROSS SOUTHEAST CANADA/THE NORTHEAST CONUS...AND ALONG THE
NORTHERN PERIPHERY OF AN EXPANSIVE SOUTHERN CONUS RIDGE
AXIS...WHICH INSTEAD OF BEING OVERHEAD AS THE CURRENT ONE
IS...THIS TIME SETS UP FARTHER SOUTH MORE OVER OK/TX. WITH THE
REMNANT...GENERALLY EAST-WEST SURFACE FRONT REMAINING IN PLACE
NEAR OR OVER THE CWA DURING THE TIME...AND WITH THE AREA BEING
PRONE TO MAINLY NOCTURNAL INCREASES IN THETA-E ADVECTION IN THE
850-700MB LAYER...THERE COULD BE SEVERAL ROUNDS OF
SHOWERS/STORMS...AND MAYBE EVEN AN OCCASIONAL SEVERE THREAT. TEMP-
WISE...LITTLE CHANGE FROM PREVIOUS WITH HIGHS GENERALLY LOW-MID
80S MOST AREAS...ALTHOUGH SOME 70S NOT OUT OF THE QUESTION.
SATURDAY...HAVE LEFT OUT POPS FOR NOW DUE TO INCREASING MODEL
VARIABILITY AND UNCERTAINTY AT THIS TIME RANGE..BUT DRY IS NO
GUARANTEE...WITH THE LOCAL AREA REMAINING NORTH OF THE SOUTHERN
PLAINS RIDGE AND POSSIBLY IN THE PATH OF SOME LOW AMPLITUDE
DISTURBANCES BRUSHING BY THROUGH THE NORTHERN PLAINS. WILL CALL
FOR MAINLY MID 80S IN NEB ZONES AND UPPER 80S IN KS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 536 AM CDT SUN SEP 8 2013
MAIN CONCERN FOR THE TAF PERIOD IS IFR/LIFR CIGS/VSBYS IN
FOG/STRATUS FOR A COUPLE OF HOURS THIS MORNING. CIGS AND VSBYS
WILL IMPROVE AFTER SUNRISE...WITH VFR CONDITIONS EXPECTED FOR THE
REMAINDER OF THE TAF PERIOD. THERE IS AN OUTSIDE CHC FOR AN
ISOLATED STORM LATE THIS AFTN/EVE BUT CHCS ARE NOT GREAT ENOUGH TO
INCLUDE ATTM. WINDS WILL TRANSITION SOUTHERLY AFTER A WARM FRONT
LIFTS NORTH OF KGRI.
&&
.FIRE WEATHER...
ISSUED AT 453 AM CDT SUN SEP 8 2013
AS PREVIOUSLY DISCUSSED OVER THE PAST 24 HOURS...MONDAY CONTINUES
TO APPEAR A DECENT CANDIDATE FOR NEAR-CRITICAL TO POTENTIALLY
CRITICAL FIRE DANGER ACROSS PARTS OF THE CWA. ON SATURDAY...AREA
FIRE WEATHER MANAGERS DEEMED VEGETATIVE FUELS ACROSS OUR KS ZONES
TO BE DRY ENOUGH TO SUPPORT POSSIBLE HEADLINES...ALTHOUGH FUELS
ACROSS OUR NEBRASKA COUNTIES ARE STILL ASSUMED TO BE GREEN ENOUGH
TO PRECLUDE MAJOR ISSUES BARRING FURTHER INFORMATION. AS LONG AS
FUELS ARE DEEMED FAVORABLE...CRITICAL FIRE WEATHER THRESHOLDS
ACROSS THE GID CWA INCLUDE A COMBINATION OF RELATIVE HUMIDITY
AT/BELOW 20 PERCENT AND SUSTAINED WINDS/GUSTS OF 20 MPH/25 MPH FOR
3+ HOURS. AS THE FORECAST CURRENTLY STANDS...A DECENT OVERLAP OF
THESE WIND/RH PARAMETERS IS ANTICIPATED ACROSS MUCH OF THE
SOUTHWESTERN HALF OF THE CWA MONDAY AFTERNOON...AS INCREASING
SOUTHWESTERLY WINDS ALLOW HOT...DRY AIR TO OVERSPREAD THE AREA.
EVEN IN NORTHEAST PORTIONS OF THE CWA...RH VALUES ARE FORECAST TO
DROP BETWEEN 21-30 PERCENT...SO THERE COULD BE AT LEAST SOME
DEGREE OF FIRE DANGER THERE AS WELL DESPITE THE OVERALL GREENER
FUELS. GIVEN THAT MONDAY AFTERNOON IS STILL 30+ HOURS AWAY AND
STILL SUBJECT TO SOME FINE-TUNING...AND AFTER COORDINATION WITH
SURROUNDING OFFICES...WILL HOLD OFF ON ANY FIRE WEATHER HEADLINES
FOR KS ZONES AT THIS TIME...BUT WILL CONTINUE TO ADVERTISE NEAR-
CRITICAL TO POTENTIALLY CRITICAL CONDITIONS IN THE HAZARDOUS
WEATHER OUTLOOK.
&&
.CLIMATE...
ISSUED AT 453 AM CDT SUN SEP 8 2013
ALTHOUGH CURRENT FORECAST HIGH TEMPERATURES TODAY/MONDAY AT OUR
PRIMARY CLIMATE RECORD SITES GRAND ISLAND/HASTINGS ARE CURRENTLY
FORECAST SLIGHTLY SHY OF RECORDS...IT COULD BE A PRETTY CLOSE
CALL. THOSE RECORDS ARE AS FOLLOWS...
SUNDAY SEP. 8...GRAND ISLAND 101 IN 1931 AND 1928
HASTINGS 101 IN 1931
MONDAY SEP. 9...GRAND ISLAND 104 IN 1931
HASTINGS 102 IN 1919
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR NEZ039>041-
046>048-060>063.
KS...NONE.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...FAY
LONG TERM...PFANNKUCH
AVIATION...FAY
FIRE WEATHER...PFANNKUCH
CLIMATE...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
908 AM CDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 908 AM CDT SUN SEP 8 2013
THE DENSE FOG ADVY HAS BEEN EXTENDED ONE MORE HOUR PER WEBCAMS...
AIRPORT VSBYS AND VIS SATELLITE. USING CONDITIONAL CLIMATOLOGY
/LOOKING BACK AT PAST SIMILAR EVENTS DURING AUG-SEP/ THE
PROBABILITY OF IFR CIG/VSBY CONTS VERY HIGH /81 PERCENT/ THRU 14Z
AND THEN DROPS TO 62 PERCENT 15Z AND 38 PERCENT BY 16Z.
SATELLITE SHOWS A DRY OUTFLOW BOUNDARY FROM OVERNGT TSTMS
APPROACHING NEB HWY 92. THIS WILL SHIFT WINDS TO NE AS ALREADY
SEEN AT ODX/BVN. THIS WILL COMPLICATE THE FCST HIGHS TODAY AND
DEPENDING ON ITS DENSITY IT MAY PREVENT THE E-W TROF FROM LIFTING
BACK N.
MRNG DATA DIAGNOSIS IS STILL ON-GOING...BUT ENVISION DWPTS WILL
NEED TO BE LOWERED SUBSTANTIALLY S AND W OF THE TRI-CITIES. HIGH
TEMPS IN THE 100S VIRTUALLY GUARANTEES MIN RH DROPPING INTO THE
TEENS THIS AFTN.
MORE LATER...
UPDATE ISSUED AT 706 AM CDT SUN SEP 8 2013
WITHIN THE PAST HOUR...DENSE FOG HAS EXPANDED IN COVERAGE EASTWARD
ACROSS MOST COUNTIES MAINLY ALONG/NORTH OF THE INTERSTATE 80
CORRIDOR PER AUTOMATED AIRPORT OBS AND WEBCAMS...WHILE
MAINTAINING INTENSITY FARTHER SOUTHWEST INTO THE HOLDREGE AREA AS
WELL. AS A RESULT...HAVE ADDED SEVERAL MORE COUNTIES TO THE DENSE
FOG ADVISORY...WHICH NOW INCLUDES GENERALLY ALL AREAS NORTH OF AN
ELWOOD-HASTINGS-YORK LINE. THE LATEST HRRR VISIBILITY PRODUCT HAS
CAPTURED THE AREA OF DENSE FOG FAIRLY WELL...AND SUGGESTS MOST OF
IT SHOULD LIFT/IMPROVE CONSIDERABLY BY 9 AM OR SO...BUT COULD
MAYBE LINGER CLOSER TO 10 AM IN THE CORE OF THE FOG AREA. INCOMING
DAY SHIFT WILL MONITOR TRENDS AND ADJUST HEADLINE AS NECESSARY.
UPDATE ISSUED AT 546 AM CDT SUN SEP 8 2013
WENT AHEAD WITH A DENSE FOG ADVISORY FOR A FEW HOURS THIS MORNING
FOR AREAS GENERALLY WEST OF HIGHWAY 281 AND ALONG THE INTERSTATE
80 CORRIDOR WHERE VSBY AVERAGE ONE QUARTER MILE OR LESS. VSBYS
WILL IMPROVE AFTER SUNRISE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 453 AM CDT SUN SEP 8 2013
AN UPPER LEVEL RIDGE OF HIGH PRESSURE CONTINUES TO DOMINATE THE
WEATHER PATTERN ACROSS THE INTERIOR CONUS...RESULTING IN HOT
TEMPERATURES FOR EARLY SEPTEMBER...WELL ABOVE NORMAL. AT THE
SURFACE...LOW PRESSURE WAS CENTERED ALONG THE WY/NEB BORDER...WITH
A STALLED FRONTAL BOUNDARY EXTENDING EASTWARD ALONG THE NEB/KS
STATELINE. HIGH DPS IN THE UPPER 60S TO AROUND 70 HAVE POOLED NORTH
OF THE BOUNDARY AND IN PRESENCE OF THE LLVL MOISTURE...SOME PATCHY
FOG HAS DEVELOPED WITH THE LOWEST VSBYS SO FAR AROUND ONE OR TWO
MILES. WILL CONTINUE TO MONITOR VSBY TRENDS THRU THE PRE DAWN
HOURS AS MODELS ARE NOT IN AGREEMENT ON HOW SIGNIFICANT FOG WILL BE
...AND THE HRRR SUGGESTS POTENTIAL FOR DENSE FOG.
THE FRONTAL BOUNDARY ALONG THE NEB/KS STATELINE WILL LIFT NORTH AS A
WARM FRONT TODAY AND TEMPERATURES WILL BE TOASTY WITH READINGS
RISING WELL INTO THE 90S...AND OUR WESTERN/SOUTHERN ZONES WILL BE
EVEN WARMER WITH HIGHS IN THE 100 TO 105F RANGE. HEAT INDICES WILL
BE FAIRLY CLOSE OR JUST BELOW AMBIENT TEMPS AS DPS LOWER BEHIND
BOUNDARY...AND SHOULD REMAIN SHY OF HEAT ADVISORY CRITERIA.
CANNOT COMPLETELY RULE OUT THE POTENTIAL FOR AN ISOLATED
THUNDERSTORM THIS AFTERNOON/EVENING...GENERALLY NORTH OF INTERSTATE
80 AS THE WARM FRONTAL BOUNDARY LIFTS ACROSS. MODELS INDICATE
PRESENCE OF MID LEVEL WAA AND FRONTOGENESIS BETWEEN H85 AND H7 NORTH
OF I-80 AND DAYTIME HIGHS ARE RIGHT AROUND CONVECTIVE TEMPERATURES.
BOTH THE NAM/GFS INDICATE THE LIFT/FORCING...BUT ONLY THE 4KM SPC
WRF INDICATES DEVELOPMENT. THE CONVECTIVE POTENTIAL IS LIMITED WITH
CAPPING/WARM MID LEVEL TEMPS...BUT CANNOT RULE OUT AN ISOLATED CHC
AND HAVE ADDED SMALL POPS.
DRY AND MILD CONDITIONS ARE FORECAST LATE EVENING ON...WITH LOWS
AVERAGING IN THE UPPER 60S TO AROUND 70F.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 453 AM CDT SUN SEP 8 2013
THERE CONTINUES TO REMAIN A FAIRLY CONSISTENT FORECAST THEME
THROUGH THESE 6 DAYS...WITH MONDAY FEATURING THE FINALE OF A
MEMORABLE EARLY SEPTEMBER HOT SPELL...ALTHOUGH TUESDAY STILL LOOKS
PLENTY TOASTY AS WELL ACROSS ROUGHLY THE SOUTHEASTERN 1/3 OF THE
CWA WITH HIGHS BETWEEN 90-95. THEREAFTER...THE WED-SAT TIME FRAME
IS EXPECTED TO FEATURE HIGHS PREDOMINANTLY IN THE 80S...WHICH ON
SEVERAL DAYS WILL STILL BE A FEW DEGREES ABOVE NORMAL DESPITE
BEING MORE SEASONABLE. AS FOR SHOWER/THUNDERSTORM CHANCES...THERE
REMAINS AT LEAST A SLIGHT CHANCE MENTION IN THE FORECAST FOR AT
LEAST A PORTION OF THE OUTLOOK AREA DURING EVERY PERIOD FROM
MONDAY NIGHT THROUGH FRIDAY NIGHT...WITH SATURDAY VOID OF
MENTIONABLE POPS...AT LEAST FOR NOW. IF ANYTHING...UNCERTAINTY
CONTINUES TO GROW REGARDING WHICH OF THESE PERIODS MIGHT BE
FAVORED FOR MORE WIDESPREAD PRECIPITATION COVERAGE...SO FOR NOW
MOST OF THESE CHANCES CONTINUE TO BE HELD DOWN IN THE 20-30
PERCENT RANGE. AS DISCUSSED OVER THE PAST 24 HOURS...MONDAY COULD
POTENTIALLY FEATURE SOME OF THE HIGHEST FIRE DANGER THE LOCAL AREA
HAS SEEN THIS SUMMER...AND THESE CONCERNS ARE OUTLINED IN GREATER
DETAIL IN THE SEPARATE FIRE WEATHER SECTION BELOW.
STARTING WITH MONDAY/MONDAY NIGHT...THE LATEST 00Z/06Z MODELS ARE
IN GOOD AGREEMENT ON THE BIG PICTURE ALOFT...WITH THE LOCAL AREA
EXPERIENCING SOUTHWESTERLY FLOW ALOFT AS THE CENTER OF THE
EXPANSIVE RIDGE AXIS CURRENTLY PARKED OVERHEAD CONTINUES TO DRIFT
FARTHER AWAY INTO THE SOUTHEAST STATES...AS A PROGRESSIVE
SHORTWAVE TROUGH TRANSLATES ALONG THE U.S./CANADA BORDER FROM A
CENTRAL POSITION OVER NORTHERN MT AT SUNRISE MONDAY...TO NORTHERN
MN BY SUNRISE TUESDAY. IN RESPONSE...A MODEST COLD FRONT WILL
DRIFT SOUTHEASTWARD INTO THE CENTRAL PLAINS. DURING THE DAYTIME
MONDAY...THE CWA WILL REMAIN JUST AHEAD OF THIS COLD FRONT...WHICH
IS FORECAST TO ALIGN FROM NORTHEAST TO TO NORTH CENTRAL NEB BY
LATE AFTERNOON...BEFORE SLOWLY INFILTRATING MUCH OF THE
NORTHERN/CENTRAL CWA MONDAY NIGHT. THE DAYTIME HOURS SHOULD BE
ANOTHER HOT ONE AREA-WIDE...AS SUSTAINED SOUTH-SOUTHWEST WINDS
PICK UP TO AT LEAST 15-20 MPH WITH GUSTS 25+ MPH IN MOST
AREAS...EXCEPT FOR A BIT LIGHTER SPEEDS POSSIBLE IN FAR NORTHWEST
COUNTIES IN CLOSET PROXIMITY TO THE APPROACHING TROUGH AXIS. WITH
DEEP MIXING FORECAST TO AVERAGE UP TO AROUND 750 MILLIBARS OVER
MUCH OF THE CWA...ANTICIPATE DEWPOINTS TO FALL WELL DOWN INTO THE
50S DURING THE AFTERNOON...WITH 40S IN SEVERAL SOUTHWESTERN
COUNTIES. IN THEORY...THIS SETUP SHOULD SET THE STAGE FOR SOME OF
THE HOTTEST READINGS OF THIS ENTIRE HOT STRETCH...ESPECIALLY IN
CENTRAL/NORTHEAST COUNTIES...BUT SOMEWHAT ODDLY MET/MAV GUIDANCE
SUGGESTS HIGHS MONDAY WOULD BE A TOUCH COOLER THAN THOSE TODAY.
DESPITE THIS...HAVE KEPT FORECAST HIGHS AT LEAST A FEW DEGREES
ABOVE A GUIDANCE BLEND IN MOST AREAS...WITH ALL BUT THE FAR
NORTHERN CWA AIMED TO TOP OUT SOMEWHERE IN THE 98-103 RANGE...WITH
THE HIGHER END OF THIS RANGE IN FAR SOUTHERN/SOUTHWEST COUNTIES.
DUE TO THE LOWER DEWPOINTS...HEAT INDEX VALUES IN MOST AREAS ONLY
AVERAGE 95-100 DEGREES. AS FOR STORM CHANCES...MODELS VARY ON HOW
AGGRESSIVELY CONVECTION MAY TRY TO SLIP INTO OUR FAR NORTHWEST
ZONES MONDAY EVENING/NIGHT...WITH SOME BRINGING THEM JUST IN WHILE
OTHERS KEEP THEM JUST OUTSIDE. GIVEN THE SLOWING NATURE OF THE
SURFACE FRONT...HAVE BACKED OFF MON NIGHT POPS TO ONLY ABOUT THE
NORTHWESTERN 1/4 OF THE CWA...WHILE THE VAST MAJORITY OF THE CWA
STAYS DRY. ALTHOUGH ANY MARGINAL SEVERE THREAT DURING THE LATE
AFTERNOON/EVENING SHOULD LARGELY TARGET THE SANDHILLS REGION JUST
TO OUR NORTHWEST...SUPPOSE A STRONG TO MARGINALLY SEVERE STORM OR
TWO CANNOT BE RULED OUT SLIPPING INTO OUR AREA...WITH THE MAIN
THREAT BEING GUSTY WINDS DUE TO HIGH CLOUD BASES IN THE DEEPLY-
MIXED AIRMASS NEAR THE FRONT. SEVERE PARAMETERS ARE NOT ALL THAT
IMPRESSIVE...WITH THE GFS SUGGESTING EARLY EVENING CAPE AVERAGING
WELL UNDER 1000 J/KG...ALTHOUGH DEEP LAYER SHEAR ISN/T ALL THAT
POOR AROUND 30-40 KNOTS.
TUESDAY/TUES NIGHT...THE NORTHERN MN SHORTWAVE TROUGH QUICKLY
SLIDES EAST INTO SOUTHEAST CANADA...AND ALTHOUGH THE CWA SEES A
PERIOD OF DECENT UPPER JET ENTRANCE REGION LIFT AND ASSOCIATED MID
LEVEL FRONTOGENESIS...THE MAIN FORCING STEADILY SLIDES AWAY TO THE
NORTHEAST...ALLOWING THE SURFACE FRONT TO LOSE STEAM AND GENERALLY
STALL OUT WITHIN OR NEAR THE SOUTHERN EDGE OF THE CWA BY TUESDAY
AFTERNOON/NIGHT. THERE COULD BE A DECENT TEMP GRADIENT IN HIGHS
TUESDAY AFTERNOON...AND HAVE MADE LITTLE CHANGE...STILL AIMING FOR
LOW-MID 80S NORTHWEST TO LOW-MID 90S SOUTHEAST. IF ENOUGH
INSTABILITY BUILDS ALONG THE SURFACE BOUNDARY...COULD MAYBE SEE
SOME STRONG TO SEVERE NEAR-SURFACE BASED STORMS FLARE UP IN
SOUTHERN COUNTIES TUESDAY AFTERNOON/EVENING...WITH MORE ELEVATED
ACTIVITY DEVELOPING FARTHER NORTH AS THE NIGHT WEARS ON IN RESPONSE
TO MID-LEVEL THETA-E ADVECTION. EVEN ONLY 3 DAYS
AWAY...UNCERTAINTY IS VERY HIGH HERE...AND HAVE KEPT DAYTIME POPS
IN SLIGHT CHANCE RANGE...WITH A GREATER COVERAGE OF 30 POPS
TUESDAY NIGHT.
WEDNESDAY THROUGH FRIDAY NIGHT...THERE CONTINUES MULTIPLE...MAINLY
20-30 PERCENT POPS ACROSS ALL/MOST OF THE CWA...AND OBVIOUSLY A
LOT OF FINE-TUNING WILL NEED DONE HERE IN THE COMING DAYS. ON THE
LARGE SCALE ALOFT...THE LOCAL AREA SETS UP UNDER FAIRLY WEAK WEST-
SOUTHWEST FLOW ALOFT...IN THE WAKE OF A DEEPENING TROUGH MIGRATING
ACROSS SOUTHEAST CANADA/THE NORTHEAST CONUS...AND ALONG THE
NORTHERN PERIPHERY OF AN EXPANSIVE SOUTHERN CONUS RIDGE
AXIS...WHICH INSTEAD OF BEING OVERHEAD AS THE CURRENT ONE
IS...THIS TIME SETS UP FARTHER SOUTH MORE OVER OK/TX. WITH THE
REMNANT...GENERALLY EAST-WEST SURFACE FRONT REMAINING IN PLACE
NEAR OR OVER THE CWA DURING THE TIME...AND WITH THE AREA BEING
PRONE TO MAINLY NOCTURNAL INCREASES IN THETA-E ADVECTION IN THE
850-700MB LAYER...THERE COULD BE SEVERAL ROUNDS OF
SHOWERS/STORMS...AND MAYBE EVEN AN OCCASIONAL SEVERE THREAT. TEMP-
WISE...LITTLE CHANGE FROM PREVIOUS WITH HIGHS GENERALLY LOW-MID
80S MOST AREAS...ALTHOUGH SOME 70S NOT OUT OF THE QUESTION.
SATURDAY...HAVE LEFT OUT POPS FOR NOW DUE TO INCREASING MODEL
VARIABILITY AND UNCERTAINTY AT THIS TIME RANGE..BUT DRY IS NO
GUARANTEE...WITH THE LOCAL AREA REMAINING NORTH OF THE SOUTHERN
PLAINS RIDGE AND POSSIBLY IN THE PATH OF SOME LOW AMPLITUDE
DISTURBANCES BRUSHING BY THROUGH THE NORTHERN PLAINS. WILL CALL
FOR MAINLY MID 80S IN NEB ZONES AND UPPER 80S IN KS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 536 AM CDT SUN SEP 8 2013
MAIN CONCERN FOR THE TAF PERIOD IS IFR/LIFR CIGS/VSBYS IN
FOG/STRATUS FOR A COUPLE OF HOURS THIS MORNING. CIGS AND VSBYS
WILL IMPROVE AFTER SUNRISE...WITH VFR CONDITIONS EXPECTED FOR THE
REMAINDER OF THE TAF PERIOD. THERE IS AN OUTSIDE CHC FOR AN
ISOLATED STORM LATE THIS AFTN/EVE BUT CHCS ARE NOT GREAT ENOUGH TO
INCLUDE ATTM. WINDS WILL TRANSITION SOUTHERLY AFTER A WARM FRONT
LIFTS NORTH OF KGRI.
&&
.FIRE WEATHER...
ISSUED AT 453 AM CDT SUN SEP 8 2013
AS PREVIOUSLY DISCUSSED OVER THE PAST 24 HOURS...MONDAY CONTINUES
TO APPEAR A DECENT CANDIDATE FOR NEAR-CRITICAL TO POTENTIALLY
CRITICAL FIRE DANGER ACROSS PARTS OF THE CWA. ON SATURDAY...AREA
FIRE WEATHER MANAGERS DEEMED VEGETATIVE FUELS ACROSS OUR KS ZONES
TO BE DRY ENOUGH TO SUPPORT POSSIBLE HEADLINES...ALTHOUGH FUELS
ACROSS OUR NEBRASKA COUNTIES ARE STILL ASSUMED TO BE GREEN ENOUGH
TO PRECLUDE MAJOR ISSUES BARRING FURTHER INFORMATION. AS LONG AS
FUELS ARE DEEMED FAVORABLE...CRITICAL FIRE WEATHER THRESHOLDS
ACROSS THE GID CWA INCLUDE A COMBINATION OF RELATIVE HUMIDITY
AT/BELOW 20 PERCENT AND SUSTAINED WINDS/GUSTS OF 20 MPH/25 MPH FOR
3+ HOURS. AS THE FORECAST CURRENTLY STANDS...A DECENT OVERLAP OF
THESE WIND/RH PARAMETERS IS ANTICIPATED ACROSS MUCH OF THE
SOUTHWESTERN HALF OF THE CWA MONDAY AFTERNOON...AS INCREASING
SOUTHWESTERLY WINDS ALLOW HOT...DRY AIR TO OVERSPREAD THE AREA.
EVEN IN NORTHEAST PORTIONS OF THE CWA...RH VALUES ARE FORECAST TO
DROP BETWEEN 21-30 PERCENT...SO THERE COULD BE AT LEAST SOME
DEGREE OF FIRE DANGER THERE AS WELL DESPITE THE OVERALL GREENER
FUELS. GIVEN THAT MONDAY AFTERNOON IS STILL 30+ HOURS AWAY AND
STILL SUBJECT TO SOME FINE-TUNING...AND AFTER COORDINATION WITH
SURROUNDING OFFICES...WILL HOLD OFF ON ANY FIRE WEATHER HEADLINES
FOR KS ZONES AT THIS TIME...BUT WILL CONTINUE TO ADVERTISE NEAR-
CRITICAL TO POTENTIALLY CRITICAL CONDITIONS IN THE HAZARDOUS
WEATHER OUTLOOK.
&&
.CLIMATE...
ISSUED AT 453 AM CDT SUN SEP 8 2013
ALTHOUGH CURRENT FORECAST HIGH TEMPERATURES TODAY/MONDAY AT OUR
PRIMARY CLIMATE RECORD SITES GRAND ISLAND/HASTINGS ARE CURRENTLY
FORECAST SLIGHTLY SHY OF RECORDS...IT COULD BE A PRETTY CLOSE
CALL. THOSE RECORDS ARE AS FOLLOWS...
SUNDAY SEP. 8...GRAND ISLAND 101 IN 1931 AND 1928
HASTINGS 101 IN 1931
MONDAY SEP. 9...GRAND ISLAND 104 IN 1931
HASTINGS 102 IN 1919
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR NEZ039>041-
046>048-060>063.
KS...NONE.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...FAY
LONG TERM...PFANNKUCH
AVIATION...FAY
FIRE WEATHER...PFANNKUCH
CLIMATE...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
707 AM CDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 706 AM CDT SUN SEP 8 2013
WITHIN THE PAST HOUR...DENSE FOG HAS EXPANDED IN COVERAGE EASTWARD
ACROSS MOST COUNTIES MAINLY ALONG/NORTH OF THE INTERSTATE 80
CORRIDOR PER AUTOMATED AIRPORT OBS AND WEBCAMS...WHILE
MAINTAINING INTENSITY FARTHER SOUTHWEST INTO THE HOLDREGE AREA AS
WELL. AS A RESULT...HAVE ADDED SEVERAL MORE COUNTIES TO THE DENSE
FOG ADVISORY...WHICH NOW INCLUDES GENERALLY ALL AREAS NORTH OF AN
ELWOOD-HASTINGS-YORK LINE. THE LATEST HRRR VISIBILITY PRODUCT HAS
CAPTURED THE AREA OF DENSE FOG FAIRLY WELL...AND SUGGESTS MOST OF
IT SHOULD LIFT/IMPROVE CONSIDERABLY BY 9 AM OR SO...BUT COULD
MAYBE LINGER CLOSER TO 10 AM IN THE CORE OF THE FOG AREA. INCOMING
DAY SHIFT WILL MONITOR TRENDS AND ADJUST HEADLINE AS NECESSARY.
UPDATE ISSUED AT 546 AM CDT SUN SEP 8 2013
WENT AHEAD WITH A DENSE FOG ADVISORY FOR A FEW HOURS THIS MORNING
FOR AREAS GENERALLY WEST OF HIGHWAY 281 AND ALONG THE INTERSTATE
80 CORRIDOR WHERE VSBY AVERAGE ONE QUARTER MILE OR LESS. VSBYS
WILL IMPROVE AFTER SUNRISE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 453 AM CDT SUN SEP 8 2013
AN UPPER LEVEL RIDGE OF HIGH PRESSURE CONTINUES TO DOMINATE THE
WEATHER PATTERN ACROSS THE INTERIOR CONUS...RESULTING IN HOT
TEMPERATURES FOR EARLY SEPTEMBER...WELL ABOVE NORMAL. AT THE
SURFACE...LOW PRESSURE WAS CENTERED ALONG THE WY/NEB BORDER...WITH
A STALLED FRONTAL BOUNDARY EXTENDING EASTWARD ALONG THE NEB/KS
STATELINE. HIGH DPS IN THE UPPER 60S TO AROUND 70 HAVE POOLED NORTH
OF THE BOUNDARY AND IN PRESENCE OF THE LLVL MOISTURE...SOME PATCHY
FOG HAS DEVELOPED WITH THE LOWEST VSBYS SO FAR AROUND ONE OR TWO
MILES. WILL CONTINUE TO MONITOR VSBY TRENDS THRU THE PRE DAWN
HOURS AS MODELS ARE NOT IN AGREEMENT ON HOW SIGNIFICANT FOG WILL BE
...AND THE HRRR SUGGESTS POTENTIAL FOR DENSE FOG.
THE FRONTAL BOUNDARY ALONG THE NEB/KS STATELINE WILL LIFT NORTH AS A
WARM FRONT TODAY AND TEMPERATURES WILL BE TOASTY WITH READINGS
RISING WELL INTO THE 90S...AND OUR WESTERN/SOUTHERN ZONES WILL BE
EVEN WARMER WITH HIGHS IN THE 100 TO 105F RANGE. HEAT INDICES WILL
BE FAIRLY CLOSE OR JUST BELOW AMBIENT TEMPS AS DPS LOWER BEHIND
BOUNDARY...AND SHOULD REMAIN SHY OF HEAT ADVISORY CRITERIA.
CANNOT COMPLETELY RULE OUT THE POTENTIAL FOR AN ISOLATED
THUNDERSTORM THIS AFTERNOON/EVENING...GENERALLY NORTH OF INTERSTATE
80 AS THE WARM FRONTAL BOUNDARY LIFTS ACROSS. MODELS INDICATE
PRESENCE OF MID LEVEL WAA AND FRONTOGENESIS BETWEEN H85 AND H7 NORTH
OF I-80 AND DAYTIME HIGHS ARE RIGHT AROUND CONVECTIVE TEMPERATURES.
BOTH THE NAM/GFS INDICATE THE LIFT/FORCING...BUT ONLY THE 4KM SPC
WRF INDICATES DEVELOPMENT. THE CONVECTIVE POTENTIAL IS LIMITED WITH
CAPPING/WARM MID LEVEL TEMPS...BUT CANNOT RULE OUT AN ISOLATED CHC
AND HAVE ADDED SMALL POPS.
DRY AND MILD CONDITIONS ARE FORECAST LATE EVENING ON...WITH LOWS
AVERAGING IN THE UPPER 60S TO AROUND 70F.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 453 AM CDT SUN SEP 8 2013
THERE CONTINUES TO REMAIN A FAIRLY CONSISTENT FORECAST THEME
THROUGH THESE 6 DAYS...WITH MONDAY FEATURING THE FINALE OF A
MEMORABLE EARLY SEPTEMBER HOT SPELL...ALTHOUGH TUESDAY STILL LOOKS
PLENTY TOASTY AS WELL ACROSS ROUGHLY THE SOUTHEASTERN 1/3 OF THE
CWA WITH HIGHS BETWEEN 90-95. THEREAFTER...THE WED-SAT TIME FRAME
IS EXPECTED TO FEATURE HIGHS PREDOMINANTLY IN THE 80S...WHICH ON
SEVERAL DAYS WILL STILL BE A FEW DEGREES ABOVE NORMAL DESPITE
BEING MORE SEASONABLE. AS FOR SHOWER/THUNDERSTORM CHANCES...THERE
REMAINS AT LEAST A SLIGHT CHANCE MENTION IN THE FORECAST FOR AT
LEAST A PORTION OF THE OUTLOOK AREA DURING EVERY PERIOD FROM
MONDAY NIGHT THROUGH FRIDAY NIGHT...WITH SATURDAY VOID OF
MENTIONABLE POPS...AT LEAST FOR NOW. IF ANYTHING...UNCERTAINTY
CONTINUES TO GROW REGARDING WHICH OF THESE PERIODS MIGHT BE
FAVORED FOR MORE WIDESPREAD PRECIPITATION COVERAGE...SO FOR NOW
MOST OF THESE CHANCES CONTINUE TO BE HELD DOWN IN THE 20-30
PERCENT RANGE. AS DISCUSSED OVER THE PAST 24 HOURS...MONDAY COULD
POTENTIALLY FEATURE SOME OF THE HIGHEST FIRE DANGER THE LOCAL AREA
HAS SEEN THIS SUMMER...AND THESE CONCERNS ARE OUTLINED IN GREATER
DETAIL IN THE SEPARATE FIRE WEATHER SECTION BELOW.
STARTING WITH MONDAY/MONDAY NIGHT...THE LATEST 00Z/06Z MODELS ARE
IN GOOD AGREEMENT ON THE BIG PICTURE ALOFT...WITH THE LOCAL AREA
EXPERIENCING SOUTHWESTERLY FLOW ALOFT AS THE CENTER OF THE
EXPANSIVE RIDGE AXIS CURRENTLY PARKED OVERHEAD CONTINUES TO DRIFT
FARTHER AWAY INTO THE SOUTHEAST STATES...AS A PROGRESSIVE
SHORTWAVE TROUGH TRANSLATES ALONG THE U.S./CANADA BORDER FROM A
CENTRAL POSITION OVER NORTHERN MT AT SUNRISE MONDAY...TO NORTHERN
MN BY SUNRISE TUESDAY. IN RESPONSE...A MODEST COLD FRONT WILL
DRIFT SOUTHEASTWARD INTO THE CENTRAL PLAINS. DURING THE DAYTIME
MONDAY...THE CWA WILL REMAIN JUST AHEAD OF THIS COLD FRONT...WHICH
IS FORECAST TO ALIGN FROM NORTHEAST TO TO NORTH CENTRAL NEB BY
LATE AFTERNOON...BEFORE SLOWLY INFILTRATING MUCH OF THE
NORTHERN/CENTRAL CWA MONDAY NIGHT. THE DAYTIME HOURS SHOULD BE
ANOTHER HOT ONE AREA-WIDE...AS SUSTAINED SOUTH-SOUTHWEST WINDS
PICK UP TO AT LEAST 15-20 MPH WITH GUSTS 25+ MPH IN MOST
AREAS...EXCEPT FOR A BIT LIGHTER SPEEDS POSSIBLE IN FAR NORTHWEST
COUNTIES IN CLOSET PROXIMITY TO THE APPROACHING TROUGH AXIS. WITH
DEEP MIXING FORECAST TO AVERAGE UP TO AROUND 750 MILLIBARS OVER
MUCH OF THE CWA...ANTICIPATE DEWPOINTS TO FALL WELL DOWN INTO THE
50S DURING THE AFTERNOON...WITH 40S IN SEVERAL SOUTHWESTERN
COUNTIES. IN THEORY...THIS SETUP SHOULD SET THE STAGE FOR SOME OF
THE HOTTEST READINGS OF THIS ENTIRE HOT STRETCH...ESPECIALLY IN
CENTRAL/NORTHEAST COUNTIES...BUT SOMEWHAT ODDLY MET/MAV GUIDANCE
SUGGESTS HIGHS MONDAY WOULD BE A TOUCH COOLER THAN THOSE TODAY.
DESPITE THIS...HAVE KEPT FORECAST HIGHS AT LEAST A FEW DEGREES
ABOVE A GUIDANCE BLEND IN MOST AREAS...WITH ALL BUT THE FAR
NORTHERN CWA AIMED TO TOP OUT SOMEWHERE IN THE 98-103 RANGE...WITH
THE HIGHER END OF THIS RANGE IN FAR SOUTHERN/SOUTHWEST COUNTIES.
DUE TO THE LOWER DEWPOINTS...HEAT INDEX VALUES IN MOST AREAS ONLY
AVERAGE 95-100 DEGREES. AS FOR STORM CHANCES...MODELS VARY ON HOW
AGGRESSIVELY CONVECTION MAY TRY TO SLIP INTO OUR FAR NORTHWEST
ZONES MONDAY EVENING/NIGHT...WITH SOME BRINGING THEM JUST IN WHILE
OTHERS KEEP THEM JUST OUTSIDE. GIVEN THE SLOWING NATURE OF THE
SURFACE FRONT...HAVE BACKED OFF MON NIGHT POPS TO ONLY ABOUT THE
NORTHWESTERN 1/4 OF THE CWA...WHILE THE VAST MAJORITY OF THE CWA
STAYS DRY. ALTHOUGH ANY MARGINAL SEVERE THREAT DURING THE LATE
AFTERNOON/EVENING SHOULD LARGELY TARGET THE SANDHILLS REGION JUST
TO OUR NORTHWEST...SUPPOSE A STRONG TO MARGINALLY SEVERE STORM OR
TWO CANNOT BE RULED OUT SLIPPING INTO OUR AREA...WITH THE MAIN
THREAT BEING GUSTY WINDS DUE TO HIGH CLOUD BASES IN THE DEEPLY-
MIXED AIRMASS NEAR THE FRONT. SEVERE PARAMETERS ARE NOT ALL THAT
IMPRESSIVE...WITH THE GFS SUGGESTING EARLY EVENING CAPE AVERAGING
WELL UNDER 1000 J/KG...ALTHOUGH DEEP LAYER SHEAR ISN/T ALL THAT
POOR AROUND 30-40 KNOTS.
TUESDAY/TUES NIGHT...THE NORTHERN MN SHORTWAVE TROUGH QUICKLY
SLIDES EAST INTO SOUTHEAST CANADA...AND ALTHOUGH THE CWA SEES A
PERIOD OF DECENT UPPER JET ENTRANCE REGION LIFT AND ASSOCIATED MID
LEVEL FRONTOGENESIS...THE MAIN FORCING STEADILY SLIDES AWAY TO THE
NORTHEAST...ALLOWING THE SURFACE FRONT TO LOSE STEAM AND GENERALLY
STALL OUT WITHIN OR NEAR THE SOUTHERN EDGE OF THE CWA BY TUESDAY
AFTERNOON/NIGHT. THERE COULD BE A DECENT TEMP GRADIENT IN HIGHS
TUESDAY AFTERNOON...AND HAVE MADE LITTLE CHANGE...STILL AIMING FOR
LOW-MID 80S NORTHWEST TO LOW-MID 90S SOUTHEAST. IF ENOUGH
INSTABILITY BUILDS ALONG THE SURFACE BOUNDARY...COULD MAYBE SEE
SOME STRONG TO SEVERE NEAR-SURFACE BASED STORMS FLARE UP IN
SOUTHERN COUNTIES TUESDAY AFTERNOON/EVENING...WITH MORE ELEVATED
ACTIVITY DEVELOPING FARTHER NORTH AS THE NIGHT WEARS ON IN RESPONSE
TO MID-LEVEL THETA-E ADVECTION. EVEN ONLY 3 DAYS
AWAY...UNCERTAINTY IS VERY HIGH HERE...AND HAVE KEPT DAYTIME POPS
IN SLIGHT CHANCE RANGE...WITH A GREATER COVERAGE OF 30 POPS
TUESDAY NIGHT.
WEDNESDAY THROUGH FRIDAY NIGHT...THERE CONTINUES MULTIPLE...MAINLY
20-30 PERCENT POPS ACROSS ALL/MOST OF THE CWA...AND OBVIOUSLY A
LOT OF FINE-TUNING WILL NEED DONE HERE IN THE COMING DAYS. ON THE
LARGE SCALE ALOFT...THE LOCAL AREA SETS UP UNDER FAIRLY WEAK WEST-
SOUTHWEST FLOW ALOFT...IN THE WAKE OF A DEEPENING TROUGH MIGRATING
ACROSS SOUTHEAST CANADA/THE NORTHEAST CONUS...AND ALONG THE
NORTHERN PERIPHERY OF AN EXPANSIVE SOUTHERN CONUS RIDGE
AXIS...WHICH INSTEAD OF BEING OVERHEAD AS THE CURRENT ONE
IS...THIS TIME SETS UP FARTHER SOUTH MORE OVER OK/TX. WITH THE
REMNANT...GENERALLY EAST-WEST SURFACE FRONT REMAINING IN PLACE
NEAR OR OVER THE CWA DURING THE TIME...AND WITH THE AREA BEING
PRONE TO MAINLY NOCTURNAL INCREASES IN THETA-E ADVECTION IN THE
850-700MB LAYER...THERE COULD BE SEVERAL ROUNDS OF
SHOWERS/STORMS...AND MAYBE EVEN AN OCCASIONAL SEVERE THREAT. TEMP-
WISE...LITTLE CHANGE FROM PREVIOUS WITH HIGHS GENERALLY LOW-MID
80S MOST AREAS...ALTHOUGH SOME 70S NOT OUT OF THE QUESTION.
SATURDAY...HAVE LEFT OUT POPS FOR NOW DUE TO INCREASING MODEL
VARIABILITY AND UNCERTAINTY AT THIS TIME RANGE..BUT DRY IS NO
GUARANTEE...WITH THE LOCAL AREA REMAINING NORTH OF THE SOUTHERN
PLAINS RIDGE AND POSSIBLY IN THE PATH OF SOME LOW AMPLITUDE
DISTURBANCES BRUSHING BY THROUGH THE NORTHERN PLAINS. WILL CALL
FOR MAINLY MID 80S IN NEB ZONES AND UPPER 80S IN KS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 536 AM CDT SUN SEP 8 2013
MAIN CONCERN FOR THE TAF PERIOD IS IFR/LIFR CIGS/VSBYS IN
FOG/STRATUS FOR A COUPLE OF HOURS THIS MORNING. CIGS AND VSBYS
WILL IMPROVE AFTER SUNRISE...WITH VFR CONDITIONS EXPECTED FOR THE
REMAINDER OF THE TAF PERIOD. THERE IS AN OUTSIDE CHC FOR AN
ISOLATED STORM LATE THIS AFTN/EVE BUT CHCS ARE NOT GREAT ENOUGH TO
INCLUDE ATTM. WINDS WILL TRANSITION SOUTHERLY AFTER A WARM FRONT
LIFTS NORTH OF KGRI.
&&
.FIRE WEATHER...
ISSUED AT 453 AM CDT SUN SEP 8 2013
AS PREVIOUSLY DISCUSSED OVER THE PAST 24 HOURS...MONDAY CONTINUES
TO APPEAR A DECENT CANDIDATE FOR NEAR-CRITICAL TO POTENTIALLY
CRITICAL FIRE DANGER ACROSS PARTS OF THE CWA. ON SATURDAY...AREA
FIRE WEATHER MANAGERS DEEMED VEGETATIVE FUELS ACROSS OUR KS ZONES
TO BE DRY ENOUGH TO SUPPORT POSSIBLE HEADLINES...ALTHOUGH FUELS
ACROSS OUR NEBRASKA COUNTIES ARE STILL ASSUMED TO BE GREEN ENOUGH
TO PRECLUDE MAJOR ISSUES BARRING FURTHER INFORMATION. AS LONG AS
FUELS ARE DEEMED FAVORABLE...CRITICAL FIRE WEATHER THRESHOLDS
ACROSS THE GID CWA INCLUDE A COMBINATION OF RELATIVE HUMIDITY
AT/BELOW 20 PERCENT AND SUSTAINED WINDS/GUSTS OF 20 MPH/25 MPH FOR
3+ HOURS. AS THE FORECAST CURRENTLY STANDS...A DECENT OVERLAP OF
THESE WIND/RH PARAMETERS IS ANTICIPATED ACROSS MUCH OF THE
SOUTHWESTERN HALF OF THE CWA MONDAY AFTERNOON...AS INCREASING
SOUTHWESTERLY WINDS ALLOW HOT...DRY AIR TO OVERSPREAD THE AREA.
EVEN IN NORTHEAST PORTIONS OF THE CWA...RH VALUES ARE FORECAST TO
DROP BETWEEN 21-30 PERCENT...SO THERE COULD BE AT LEAST SOME
DEGREE OF FIRE DANGER THERE AS WELL DESPITE THE OVERALL GREENER
FUELS. GIVEN THAT MONDAY AFTERNOON IS STILL 30+ HOURS AWAY AND
STILL SUBJECT TO SOME FINE-TUNING...AND AFTER COORDINATION WITH
SURROUNDING OFFICES...WILL HOLD OFF ON ANY FIRE WEATHER HEADLINES
FOR KS ZONES AT THIS TIME...BUT WILL CONTINUE TO ADVERTISE NEAR-
CRITICAL TO POTENTIALLY CRITICAL CONDITIONS IN THE HAZARDOUS
WEATHER OUTLOOK.
&&
.CLIMATE...
ISSUED AT 453 AM CDT SUN SEP 8 2013
ALTHOUGH CURRENT FORECAST HIGH TEMPERATURES TODAY/MONDAY AT OUR
PRIMARY CLIMATE RECORD SITES GRAND ISLAND/HASTINGS ARE CURRENTLY
FORECAST SLIGHTLY SHY OF RECORDS...IT COULD BE A PRETTY CLOSE
CALL. THOSE RECORDS ARE AS FOLLOWS...
SUNDAY SEP. 8...GRAND ISLAND 101 IN 1931 AND 1928
HASTINGS 101 IN 1931
MONDAY SEP. 9...GRAND ISLAND 104 IN 1931
HASTINGS 102 IN 1919
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR NEZ039>041-
046>049-060>064-072>075.
KS...NONE.
&&
$$
UPDATE...PFANNKUCH
SHORT TERM...FAY
LONG TERM...PFANNKUCH
AVIATION...FAY
FIRE WEATHER...PFANNKUCH
CLIMATE...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
548 AM CDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 546 AM CDT SUN SEP 8 2013
WENT AHEAD WITH A DENSE FOG ADVISORY FOR A FEW HOURS THIS MORNING
FOR AREAS GENERALLY WEST OF HIGHWAY 281 AND ALONG THE INTERSTATE
80 CORRIDOR WHERE VSBY AVERAGE ONE QUARTER MILE OR LESS. VSBYS
WILL IMPROVE AFTER SUNRISE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 453 AM CDT SUN SEP 8 2013
AN UPPER LEVEL RIDGE OF HIGH PRESSURE CONTINUES TO DOMINATE THE
WEATHER PATTERN ACROSS THE INTERIOR CONUS...RESULTING IN HOT
TEMPERATURES FOR EARLY SEPTEMBER...WELL ABOVE NORMAL. AT THE
SURFACE...LOW PRESSURE WAS CENTERED ALONG THE WY/NEB BORDER...WITH
A STALLED FRONTAL BOUNDARY EXTENDING EASTWARD ALONG THE NEB/KS
STATELINE. HIGH DPS IN THE UPPER 60S TO AROUND 70 HAVE POOLED NORTH
OF THE BOUNDARY AND IN PRESENCE OF THE LLVL MOISTURE...SOME PATCHY
FOG HAS DEVELOPED WITH THE LOWEST VSBYS SO FAR AROUND ONE OR TWO
MILES. WILL CONTINUE TO MONITOR VSBY TRENDS THRU THE PRE DAWN
HOURS AS MODELS ARE NOT IN AGREEMENT ON HOW SIGNIFICANT FOG WILL BE
...AND THE HRRR SUGGESTS POTENTIAL FOR DENSE FOG.
THE FRONTAL BOUNDARY ALONG THE NEB/KS STATELINE WILL LIFT NORTH AS A
WARM FRONT TODAY AND TEMPERATURES WILL BE TOASTY WITH READINGS
RISING WELL INTO THE 90S...AND OUR WESTERN/SOUTHERN ZONES WILL BE
EVEN WARMER WITH HIGHS IN THE 100 TO 105F RANGE. HEAT INDICES WILL
BE FAIRLY CLOSE OR JUST BELOW AMBIENT TEMPS AS DPS LOWER BEHIND
BOUNDARY...AND SHOULD REMAIN SHY OF HEAT ADVISORY CRITERIA.
CANNOT COMPLETELY RULE OUT THE POTENTIAL FOR AN ISOLATED
THUNDERSTORM THIS AFTERNOON/EVENING...GENERALLY NORTH OF INTERSTATE
80 AS THE WARM FRONTAL BOUNDARY LIFTS ACROSS. MODELS INDICATE
PRESENCE OF MID LEVEL WAA AND FRONTOGENESIS BETWEEN H85 AND H7 NORTH
OF I-80 AND DAYTIME HIGHS ARE RIGHT AROUND CONVECTIVE TEMPERATURES.
BOTH THE NAM/GFS INDICATE THE LIFT/FORCING...BUT ONLY THE 4KM SPC
WRF INDICATES DEVELOPMENT. THE CONVECTIVE POTENTIAL IS LIMITED WITH
CAPPING/WARM MID LEVEL TEMPS...BUT CANNOT RULE OUT AN ISOLATED CHC
AND HAVE ADDED SMALL POPS.
DRY AND MILD CONDITIONS ARE FORECAST LATE EVENING ON...WITH LOWS
AVERAGING IN THE UPPER 60S TO AROUND 70F.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 453 AM CDT SUN SEP 8 2013
THERE CONTINUES TO REMAIN A FAIRLY CONSISTENT FORECAST THEME
THROUGH THESE 6 DAYS...WITH MONDAY FEATURING THE FINALE OF A
MEMORABLE EARLY SEPTEMBER HOT SPELL...ALTHOUGH TUESDAY STILL LOOKS
PLENTY TOASTY AS WELL ACROSS ROUGHLY THE SOUTHEASTERN 1/3 OF THE
CWA WITH HIGHS BETWEEN 90-95. THEREAFTER...THE WED-SAT TIME FRAME
IS EXPECTED TO FEATURE HIGHS PREDOMINANTLY IN THE 80S...WHICH ON
SEVERAL DAYS WILL STILL BE A FEW DEGREES ABOVE NORMAL DESPITE
BEING MORE SEASONABLE. AS FOR SHOWER/THUNDERSTORM CHANCES...THERE
REMAINS AT LEAST A SLIGHT CHANCE MENTION IN THE FORECAST FOR AT
LEAST A PORTION OF THE OUTLOOK AREA DURING EVERY PERIOD FROM
MONDAY NIGHT THROUGH FRIDAY NIGHT...WITH SATURDAY VOID OF
MENTIONABLE POPS...AT LEAST FOR NOW. IF ANYTHING...UNCERTAINTY
CONTINUES TO GROW REGARDING WHICH OF THESE PERIODS MIGHT BE
FAVORED FOR MORE WIDESPREAD PRECIPITATION COVERAGE...SO FOR NOW
MOST OF THESE CHANCES CONTINUE TO BE HELD DOWN IN THE 20-30
PERCENT RANGE. AS DISCUSSED OVER THE PAST 24 HOURS...MONDAY COULD
POTENTIALLY FEATURE SOME OF THE HIGHEST FIRE DANGER THE LOCAL AREA
HAS SEEN THIS SUMMER...AND THESE CONCERNS ARE OUTLINED IN GREATER
DETAIL IN THE SEPARATE FIRE WEATHER SECTION BELOW.
STARTING WITH MONDAY/MONDAY NIGHT...THE LATEST 00Z/06Z MODELS ARE
IN GOOD AGREEMENT ON THE BIG PICTURE ALOFT...WITH THE LOCAL AREA
EXPERIENCING SOUTHWESTERLY FLOW ALOFT AS THE CENTER OF THE
EXPANSIVE RIDGE AXIS CURRENTLY PARKED OVERHEAD CONTINUES TO DRIFT
FARTHER AWAY INTO THE SOUTHEAST STATES...AS A PROGRESSIVE
SHORTWAVE TROUGH TRANSLATES ALONG THE U.S./CANADA BORDER FROM A
CENTRAL POSITION OVER NORTHERN MT AT SUNRISE MONDAY...TO NORTHERN
MN BY SUNRISE TUESDAY. IN RESPONSE...A MODEST COLD FRONT WILL
DRIFT SOUTHEASTWARD INTO THE CENTRAL PLAINS. DURING THE DAYTIME
MONDAY...THE CWA WILL REMAIN JUST AHEAD OF THIS COLD FRONT...WHICH
IS FORECAST TO ALIGN FROM NORTHEAST TO TO NORTH CENTRAL NEB BY
LATE AFTERNOON...BEFORE SLOWLY INFILTRATING MUCH OF THE
NORTHERN/CENTRAL CWA MONDAY NIGHT. THE DAYTIME HOURS SHOULD BE
ANOTHER HOT ONE AREA-WIDE...AS SUSTAINED SOUTH-SOUTHWEST WINDS
PICK UP TO AT LEAST 15-20 MPH WITH GUSTS 25+ MPH IN MOST
AREAS...EXCEPT FOR A BIT LIGHTER SPEEDS POSSIBLE IN FAR NORTHWEST
COUNTIES IN CLOSET PROXIMITY TO THE APPROACHING TROUGH AXIS. WITH
DEEP MIXING FORECAST TO AVERAGE UP TO AROUND 750 MILLIBARS OVER
MUCH OF THE CWA...ANTICIPATE DEWPOINTS TO FALL WELL DOWN INTO THE
50S DURING THE AFTERNOON...WITH 40S IN SEVERAL SOUTHWESTERN
COUNTIES. IN THEORY...THIS SETUP SHOULD SET THE STAGE FOR SOME OF
THE HOTTEST READINGS OF THIS ENTIRE HOT STRETCH...ESPECIALLY IN
CENTRAL/NORTHEAST COUNTIES...BUT SOMEWHAT ODDLY MET/MAV GUIDANCE
SUGGESTS HIGHS MONDAY WOULD BE A TOUCH COOLER THAN THOSE TODAY.
DESPITE THIS...HAVE KEPT FORECAST HIGHS AT LEAST A FEW DEGREES
ABOVE A GUIDANCE BLEND IN MOST AREAS...WITH ALL BUT THE FAR
NORTHERN CWA AIMED TO TOP OUT SOMEWHERE IN THE 98-103 RANGE...WITH
THE HIGHER END OF THIS RANGE IN FAR SOUTHERN/SOUTHWEST COUNTIES.
DUE TO THE LOWER DEWPOINTS...HEAT INDEX VALUES IN MOST AREAS ONLY
AVERAGE 95-100 DEGREES. AS FOR STORM CHANCES...MODELS VARY ON HOW
AGGRESSIVELY CONVECTION MAY TRY TO SLIP INTO OUR FAR NORTHWEST
ZONES MONDAY EVENING/NIGHT...WITH SOME BRINGING THEM JUST IN WHILE
OTHERS KEEP THEM JUST OUTSIDE. GIVEN THE SLOWING NATURE OF THE
SURFACE FRONT...HAVE BACKED OFF MON NIGHT POPS TO ONLY ABOUT THE
NORTHWESTERN 1/4 OF THE CWA...WHILE THE VAST MAJORITY OF THE CWA
STAYS DRY. ALTHOUGH ANY MARGINAL SEVERE THREAT DURING THE LATE
AFTERNOON/EVENING SHOULD LARGELY TARGET THE SANDHILLS REGION JUST
TO OUR NORTHWEST...SUPPOSE A STRONG TO MARGINALLY SEVERE STORM OR
TWO CANNOT BE RULED OUT SLIPPING INTO OUR AREA...WITH THE MAIN
THREAT BEING GUSTY WINDS DUE TO HIGH CLOUD BASES IN THE DEEPLY-
MIXED AIRMASS NEAR THE FRONT. SEVERE PARAMETERS ARE NOT ALL THAT
IMPRESSIVE...WITH THE GFS SUGGESTING EARLY EVENING CAPE AVERAGING
WELL UNDER 1000 J/KG...ALTHOUGH DEEP LAYER SHEAR ISN/T ALL THAT
POOR AROUND 30-40 KNOTS.
TUESDAY/TUES NIGHT...THE NORTHERN MN SHORTWAVE TROUGH QUICKLY
SLIDES EAST INTO SOUTHEAST CANADA...AND ALTHOUGH THE CWA SEES A
PERIOD OF DECENT UPPER JET ENTRANCE REGION LIFT AND ASSOCIATED MID
LEVEL FRONTOGENESIS...THE MAIN FORCING STEADILY SLIDES AWAY TO THE
NORTHEAST...ALLOWING THE SURFACE FRONT TO LOSE STEAM AND GENERALLY
STALL OUT WITHIN OR NEAR THE SOUTHERN EDGE OF THE CWA BY TUESDAY
AFTERNOON/NIGHT. THERE COULD BE A DECENT TEMP GRADIENT IN HIGHS
TUESDAY AFTERNOON...AND HAVE MADE LITTLE CHANGE...STILL AIMING FOR
LOW-MID 80S NORTHWEST TO LOW-MID 90S SOUTHEAST. IF ENOUGH
INSTABILITY BUILDS ALONG THE SURFACE BOUNDARY...COULD MAYBE SEE
SOME STRONG TO SEVERE NEAR-SURFACE BASED STORMS FLARE UP IN
SOUTHERN COUNTIES TUESDAY AFTERNOON/EVENING...WITH MORE ELEVATED
ACTIVITY DEVELOPING FARTHER NORTH AS THE NIGHT WEARS ON IN RESPONSE
TO MID-LEVEL THETA-E ADVECTION. EVEN ONLY 3 DAYS
AWAY...UNCERTAINTY IS VERY HIGH HERE...AND HAVE KEPT DAYTIME POPS
IN SLIGHT CHANCE RANGE...WITH A GREATER COVERAGE OF 30 POPS
TUESDAY NIGHT.
WEDNESDAY THROUGH FRIDAY NIGHT...THERE CONTINUES MULTIPLE...MAINLY
20-30 PERCENT POPS ACROSS ALL/MOST OF THE CWA...AND OBVIOUSLY A
LOT OF FINE-TUNING WILL NEED DONE HERE IN THE COMING DAYS. ON THE
LARGE SCALE ALOFT...THE LOCAL AREA SETS UP UNDER FAIRLY WEAK WEST-
SOUTHWEST FLOW ALOFT...IN THE WAKE OF A DEEPENING TROUGH MIGRATING
ACROSS SOUTHEAST CANADA/THE NORTHEAST CONUS...AND ALONG THE
NORTHERN PERIPHERY OF AN EXPANSIVE SOUTHERN CONUS RIDGE
AXIS...WHICH INSTEAD OF BEING OVERHEAD AS THE CURRENT ONE
IS...THIS TIME SETS UP FARTHER SOUTH MORE OVER OK/TX. WITH THE
REMNANT...GENERALLY EAST-WEST SURFACE FRONT REMAINING IN PLACE
NEAR OR OVER THE CWA DURING THE TIME...AND WITH THE AREA BEING
PRONE TO MAINLY NOCTURNAL INCREASES IN THETA-E ADVECTION IN THE
850-700MB LAYER...THERE COULD BE SEVERAL ROUNDS OF
SHOWERS/STORMS...AND MAYBE EVEN AN OCCASIONAL SEVERE THREAT. TEMP-
WISE...LITTLE CHANGE FROM PREVIOUS WITH HIGHS GENERALLY LOW-MID
80S MOST AREAS...ALTHOUGH SOME 70S NOT OUT OF THE QUESTION.
SATURDAY...HAVE LEFT OUT POPS FOR NOW DUE TO INCREASING MODEL
VARIABILITY AND UNCERTAINTY AT THIS TIME RANGE..BUT DRY IS NO
GUARANTEE...WITH THE LOCAL AREA REMAINING NORTH OF THE SOUTHERN
PLAINS RIDGE AND POSSIBLY IN THE PATH OF SOME LOW AMPLITUDE
DISTURBANCES BRUSHING BY THROUGH THE NORTHERN PLAINS. WILL CALL
FOR MAINLY MID 80S IN NEB ZONES AND UPPER 80S IN KS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 536 AM CDT SUN SEP 8 2013
MAIN CONCERN FOR THE TAF PERIOD IS IFR/LIFR CIGS/VSBYS IN
FOG/STRATUS FOR A COUPLE OF HOURS THIS MORNING. CIGS AND VSBYS
WILL IMPROVE AFTER SUNRISE...WITH VFR CONDITIONS EXPECTED FOR THE
REMAINDER OF THE TAF PERIOD. THERE IS AN OUTSIDE CHC FOR AN
ISOLATED STORM LATE THIS AFTN/EVE BUT CHCS ARE NOT GREAT ENOUGH TO
INCLUDE ATTM. WINDS WILL TRANSITION SOUTHERLY AFTER A WARM FRONT
LIFTS NORTH OF KGRI.
&&
.FIRE WEATHER...
ISSUED AT 453 AM CDT SUN SEP 8 2013
AS PREVIOUSLY DISCUSSED OVER THE PAST 24 HOURS...MONDAY CONTINUES
TO APPEAR A DECENT CANDIDATE FOR NEAR-CRITICAL TO POTENTIALLY
CRITICAL FIRE DANGER ACROSS PARTS OF THE CWA. ON SATURDAY...AREA
FIRE WEATHER MANAGERS DEEMED VEGETATIVE FUELS ACROSS OUR KS ZONES
TO BE DRY ENOUGH TO SUPPORT POSSIBLE HEADLINES...ALTHOUGH FUELS
ACROSS OUR NEBRASKA COUNTIES ARE STILL ASSUMED TO BE GREEN ENOUGH
TO PRECLUDE MAJOR ISSUES BARRING FURTHER INFORMATION. AS LONG AS
FUELS ARE DEEMED FAVORABLE...CRITICAL FIRE WEATHER THRESHOLDS
ACROSS THE GID CWA INCLUDE A COMBINATION OF RELATIVE HUMIDITY
AT/BELOW 20 PERCENT AND SUSTAINED WINDS/GUSTS OF 20 MPH/25 MPH FOR
3+ HOURS. AS THE FORECAST CURRENTLY STANDS...A DECENT OVERLAP OF
THESE WIND/RH PARAMETERS IS ANTICIPATED ACROSS MUCH OF THE
SOUTHWESTERN HALF OF THE CWA MONDAY AFTERNOON...AS INCREASING
SOUTHWESTERLY WINDS ALLOW HOT...DRY AIR TO OVERSPREAD THE AREA.
EVEN IN NORTHEAST PORTIONS OF THE CWA...RH VALUES ARE FORECAST TO
DROP BETWEEN 21-30 PERCENT...SO THERE COULD BE AT LEAST SOME
DEGREE OF FIRE DANGER THERE AS WELL DESPITE THE OVERALL GREENER
FUELS. GIVEN THAT MONDAY AFTERNOON IS STILL 30+ HOURS AWAY AND
STILL SUBJECT TO SOME FINE-TUNING...AND AFTER COORDINATION WITH
SURROUNDING OFFICES...WILL HOLD OFF ON ANY FIRE WEATHER HEADLINES
FOR KS ZONES AT THIS TIME...BUT WILL CONTINUE TO ADVERTISE NEAR-
CRITICAL TO POTENTIALLY CRITICAL CONDITIONS IN THE HAZARDOUS
WEATHER OUTLOOK.
&&
.CLIMATE...
ISSUED AT 453 AM CDT SUN SEP 8 2013
ALTHOUGH CURRENT FORECAST HIGH TEMPERATURES TODAY/MONDAY AT OUR
PRIMARY CLIMATE RECORD SITES GRAND ISLAND/HASTINGS ARE CURRENTLY
FORECAST SLIGHTLY SHY OF RECORDS...IT COULD BE A PRETTY CLOSE
CALL. THOSE RECORDS ARE AS FOLLOWS...
SUNDAY SEP. 8...GRAND ISLAND 101 IN 1931 AND 1928
HASTINGS 101 IN 1931
MONDAY SEP. 9...GRAND ISLAND 104 IN 1931
HASTINGS 102 IN 1919
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR NEZ046-060-
061-072>074.
KS...NONE.
&&
$$
UPDATE...FAY
SHORT TERM...FAY
LONG TERM...PFANNKUCH
AVIATION...FAY
FIRE WEATHER...PFANNKUCH
CLIMATE...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
540 AM CDT SUN SEP 8 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 453 AM CDT SUN SEP 8 2013
AN UPPER LEVEL RIDGE OF HIGH PRESSURE CONTINUES TO DOMINATE THE
WEATHER PATTERN ACROSS THE INTERIOR CONUS...RESULTING IN HOT
TEMPERATURES FOR EARLY SEPTEMBER...WELL ABOVE NORMAL. AT THE
SURFACE...LOW PRESSURE WAS CENTERED ALONG THE WY/NEB BORDER...WITH
A STALLED FRONTAL BOUNDARY EXTENDING EASTWARD ALONG THE NEB/KS
STATELINE. HIGH DPS IN THE UPPER 60S TO AROUND 70 HAVE POOLED NORTH
OF THE BOUNDARY AND IN PRESENCE OF THE LLVL MOISTURE...SOME PATCHY
FOG HAS DEVELOPED WITH THE LOWEST VSBYS SO FAR AROUND ONE OR TWO
MILES. WILL CONTINUE TO MONITOR VSBY TRENDS THRU THE PRE DAWN
HOURS AS MODELS ARE NOT IN AGREEMENT ON HOW SIGNIFICANT FOG WILL BE
...AND THE HRRR SUGGESTS POTENTIAL FOR DENSE FOG.
THE FRONTAL BOUNDARY ALONG THE NEB/KS STATELINE WILL LIFT NORTH AS A
WARM FRONT TODAY AND TEMPERATURES WILL BE TOASTY WITH READINGS
RISING WELL INTO THE 90S...AND OUR WESTERN/SOUTHERN ZONES WILL BE
EVEN WARMER WITH HIGHS IN THE 100 TO 105F RANGE. HEAT INDICES WILL
BE FAIRLY CLOSE OR JUST BELOW AMBIENT TEMPS AS DPS LOWER BEHIND
BOUNDARY...AND SHOULD REMAIN SHY OF HEAT ADVISORY CRITERIA.
CANNOT COMPLETELY RULE OUT THE POTENTIAL FOR AN ISOLATED
THUNDERSTORM THIS AFTERNOON/EVENING...GENERALLY NORTH OF INTERSTATE
80 AS THE WARM FRONTAL BOUNDARY LIFTS ACROSS. MODELS INDICATE
PRESENCE OF MID LEVEL WAA AND FRONTOGENESIS BETWEEN H85 AND H7 NORTH
OF I-80 AND DAYTIME HIGHS ARE RIGHT AROUND CONVECTIVE TEMPERATURES.
BOTH THE NAM/GFS INDICATE THE LIFT/FORCING...BUT ONLY THE 4KM SPC
WRF INDICATES DEVELOPMENT. THE CONVECTIVE POTENTIAL IS LIMITED WITH
CAPPING/WARM MID LEVEL TEMPS...BUT CANNOT RULE OUT AN ISOLATED CHC
AND HAVE ADDED SMALL POPS.
DRY AND MILD CONDITIONS ARE FORECAST LATE EVENING ON...WITH LOWS
AVERAGING IN THE UPPER 60S TO AROUND 70F.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 453 AM CDT SUN SEP 8 2013
THERE CONTINUES TO REMAIN A FAIRLY CONSISTENT FORECAST THEME
THROUGH THESE 6 DAYS...WITH MONDAY FEATURING THE FINALE OF A
MEMORABLE EARLY SEPTEMBER HOT SPELL...ALTHOUGH TUESDAY STILL LOOKS
PLENTY TOASTY AS WELL ACROSS ROUGHLY THE SOUTHEASTERN 1/3 OF THE
CWA WITH HIGHS BETWEEN 90-95. THEREAFTER...THE WED-SAT TIME FRAME
IS EXPECTED TO FEATURE HIGHS PREDOMINANTLY IN THE 80S...WHICH ON
SEVERAL DAYS WILL STILL BE A FEW DEGREES ABOVE NORMAL DESPITE
BEING MORE SEASONABLE. AS FOR SHOWER/THUNDERSTORM CHANCES...THERE
REMAINS AT LEAST A SLIGHT CHANCE MENTION IN THE FORECAST FOR AT
LEAST A PORTION OF THE OUTLOOK AREA DURING EVERY PERIOD FROM
MONDAY NIGHT THROUGH FRIDAY NIGHT...WITH SATURDAY VOID OF
MENTIONABLE POPS...AT LEAST FOR NOW. IF ANYTHING...UNCERTAINTY
CONTINUES TO GROW REGARDING WHICH OF THESE PERIODS MIGHT BE
FAVORED FOR MORE WIDESPREAD PRECIPITATION COVERAGE...SO FOR NOW
MOST OF THESE CHANCES CONTINUE TO BE HELD DOWN IN THE 20-30
PERCENT RANGE. AS DISCUSSED OVER THE PAST 24 HOURS...MONDAY COULD
POTENTIALLY FEATURE SOME OF THE HIGHEST FIRE DANGER THE LOCAL AREA
HAS SEEN THIS SUMMER...AND THESE CONCERNS ARE OUTLINED IN GREATER
DETAIL IN THE SEPARATE FIRE WEATHER SECTION BELOW.
STARTING WITH MONDAY/MONDAY NIGHT...THE LATEST 00Z/06Z MODELS ARE
IN GOOD AGREEMENT ON THE BIG PICTURE ALOFT...WITH THE LOCAL AREA
EXPERIENCING SOUTHWESTERLY FLOW ALOFT AS THE CENTER OF THE
EXPANSIVE RIDGE AXIS CURRENTLY PARKED OVERHEAD CONTINUES TO DRIFT
FARTHER AWAY INTO THE SOUTHEAST STATES...AS A PROGRESSIVE
SHORTWAVE TROUGH TRANSLATES ALONG THE U.S./CANADA BORDER FROM A
CENTRAL POSITION OVER NORTHERN MT AT SUNRISE MONDAY...TO NORTHERN
MN BY SUNRISE TUESDAY. IN RESPONSE...A MODEST COLD FRONT WILL
DRIFT SOUTHEASTWARD INTO THE CENTRAL PLAINS. DURING THE DAYTIME
MONDAY...THE CWA WILL REMAIN JUST AHEAD OF THIS COLD FRONT...WHICH
IS FORECAST TO ALIGN FROM NORTHEAST TO TO NORTH CENTRAL NEB BY
LATE AFTERNOON...BEFORE SLOWLY INFILTRATING MUCH OF THE
NORTHERN/CENTRAL CWA MONDAY NIGHT. THE DAYTIME HOURS SHOULD BE
ANOTHER HOT ONE AREA-WIDE...AS SUSTAINED SOUTH-SOUTHWEST WINDS
PICK UP TO AT LEAST 15-20 MPH WITH GUSTS 25+ MPH IN MOST
AREAS...EXCEPT FOR A BIT LIGHTER SPEEDS POSSIBLE IN FAR NORTHWEST
COUNTIES IN CLOSET PROXIMITY TO THE APPROACHING TROUGH AXIS. WITH
DEEP MIXING FORECAST TO AVERAGE UP TO AROUND 750 MILLIBARS OVER
MUCH OF THE CWA...ANTICIPATE DEWPOINTS TO FALL WELL DOWN INTO THE
50S DURING THE AFTERNOON...WITH 40S IN SEVERAL SOUTHWESTERN
COUNTIES. IN THEORY...THIS SETUP SHOULD SET THE STAGE FOR SOME OF
THE HOTTEST READINGS OF THIS ENTIRE HOT STRETCH...ESPECIALLY IN
CENTRAL/NORTHEAST COUNTIES...BUT SOMEWHAT ODDLY MET/MAV GUIDANCE
SUGGESTS HIGHS MONDAY WOULD BE A TOUCH COOLER THAN THOSE TODAY.
DESPITE THIS...HAVE KEPT FORECAST HIGHS AT LEAST A FEW DEGREES
ABOVE A GUIDANCE BLEND IN MOST AREAS...WITH ALL BUT THE FAR
NORTHERN CWA AIMED TO TOP OUT SOMEWHERE IN THE 98-103 RANGE...WITH
THE HIGHER END OF THIS RANGE IN FAR SOUTHERN/SOUTHWEST COUNTIES.
DUE TO THE LOWER DEWPOINTS...HEAT INDEX VALUES IN MOST AREAS ONLY
AVERAGE 95-100 DEGREES. AS FOR STORM CHANCES...MODELS VARY ON HOW
AGGRESSIVELY CONVECTION MAY TRY TO SLIP INTO OUR FAR NORTHWEST
ZONES MONDAY EVENING/NIGHT...WITH SOME BRINGING THEM JUST IN WHILE
OTHERS KEEP THEM JUST OUTSIDE. GIVEN THE SLOWING NATURE OF THE
SURFACE FRONT...HAVE BACKED OFF MON NIGHT POPS TO ONLY ABOUT THE
NORTHWESTERN 1/4 OF THE CWA...WHILE THE VAST MAJORITY OF THE CWA
STAYS DRY. ALTHOUGH ANY MARGINAL SEVERE THREAT DURING THE LATE
AFTERNOON/EVENING SHOULD LARGELY TARGET THE SANDHILLS REGION JUST
TO OUR NORTHWEST...SUPPOSE A STRONG TO MARGINALLY SEVERE STORM OR
TWO CANNOT BE RULED OUT SLIPPING INTO OUR AREA...WITH THE MAIN
THREAT BEING GUSTY WINDS DUE TO HIGH CLOUD BASES IN THE DEEPLY-
MIXED AIRMASS NEAR THE FRONT. SEVERE PARAMETERS ARE NOT ALL THAT
IMPRESSIVE...WITH THE GFS SUGGESTING EARLY EVENING CAPE AVERAGING
WELL UNDER 1000 J/KG...ALTHOUGH DEEP LAYER SHEAR ISN/T ALL THAT
POOR AROUND 30-40 KNOTS.
TUESDAY/TUES NIGHT...THE NORTHERN MN SHORTWAVE TROUGH QUICKLY
SLIDES EAST INTO SOUTHEAST CANADA...AND ALTHOUGH THE CWA SEES A
PERIOD OF DECENT UPPER JET ENTRANCE REGION LIFT AND ASSOCIATED MID
LEVEL FRONTOGENESIS...THE MAIN FORCING STEADILY SLIDES AWAY TO THE
NORTHEAST...ALLOWING THE SURFACE FRONT TO LOSE STEAM AND GENERALLY
STALL OUT WITHIN OR NEAR THE SOUTHERN EDGE OF THE CWA BY TUESDAY
AFTERNOON/NIGHT. THERE COULD BE A DECENT TEMP GRADIENT IN HIGHS
TUESDAY AFTERNOON...AND HAVE MADE LITTLE CHANGE...STILL AIMING FOR
LOW-MID 80S NORTHWEST TO LOW-MID 90S SOUTHEAST. IF ENOUGH
INSTABILITY BUILDS ALONG THE SURFACE BOUNDARY...COULD MAYBE SEE
SOME STRONG TO SEVERE NEAR-SURFACE BASED STORMS FLARE UP IN
SOUTHERN COUNTIES TUESDAY AFTERNOON/EVENING...WITH MORE ELEVATED
ACTIVITY DEVELOPING FARTHER NORTH AS THE NIGHT WEARS ON IN RESPONSE
TO MID-LEVEL THETA-E ADVECTION. EVEN ONLY 3 DAYS
AWAY...UNCERTAINTY IS VERY HIGH HERE...AND HAVE KEPT DAYTIME POPS
IN SLIGHT CHANCE RANGE...WITH A GREATER COVERAGE OF 30 POPS
TUESDAY NIGHT.
WEDNESDAY THROUGH FRIDAY NIGHT...THERE CONTINUES MULTIPLE...MAINLY
20-30 PERCENT POPS ACROSS ALL/MOST OF THE CWA...AND OBVIOUSLY A
LOT OF FINE-TUNING WILL NEED DONE HERE IN THE COMING DAYS. ON THE
LARGE SCALE ALOFT...THE LOCAL AREA SETS UP UNDER FAIRLY WEAK WEST-
SOUTHWEST FLOW ALOFT...IN THE WAKE OF A DEEPENING TROUGH MIGRATING
ACROSS SOUTHEAST CANADA/THE NORTHEAST CONUS...AND ALONG THE
NORTHERN PERIPHERY OF AN EXPANSIVE SOUTHERN CONUS RIDGE
AXIS...WHICH INSTEAD OF BEING OVERHEAD AS THE CURRENT ONE
IS...THIS TIME SETS UP FARTHER SOUTH MORE OVER OK/TX. WITH THE
REMNANT...GENERALLY EAST-WEST SURFACE FRONT REMAINING IN PLACE
NEAR OR OVER THE CWA DURING THE TIME...AND WITH THE AREA BEING
PRONE TO MAINLY NOCTURNAL INCREASES IN THETA-E ADVECTION IN THE
850-700MB LAYER...THERE COULD BE SEVERAL ROUNDS OF
SHOWERS/STORMS...AND MAYBE EVEN AN OCCASIONAL SEVERE THREAT. TEMP-
WISE...LITTLE CHANGE FROM PREVIOUS WITH HIGHS GENERALLY LOW-MID
80S MOST AREAS...ALTHOUGH SOME 70S NOT OUT OF THE QUESTION.
SATURDAY...HAVE LEFT OUT POPS FOR NOW DUE TO INCREASING MODEL
VARIABILITY AND UNCERTAINTY AT THIS TIME RANGE..BUT DRY IS NO
GUARANTEE...WITH THE LOCAL AREA REMAINING NORTH OF THE SOUTHERN
PLAINS RIDGE AND POSSIBLY IN THE PATH OF SOME LOW AMPLITUDE
DISTURBANCES BRUSHING BY THROUGH THE NORTHERN PLAINS. WILL CALL
FOR MAINLY MID 80S IN NEB ZONES AND UPPER 80S IN KS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 536 AM CDT SUN SEP 8 2013
MAIN CONCERN FOR THE TAF PERIOD IS IFR/LIFR CIGS/VSBYS IN
FOG/STRATUS FOR A COUPLE OF HOURS THIS MORNING. CIGS AND VSBYS
WILL IMPROVE AFTER SUNRISE...WITH VFR CONDITIONS EXPECTED FOR THE
REMAINDER OF THE TAF PERIOD. THERE IS AN OUTSIDE CHC FOR AN
ISOLATED STORM LATE THIS AFTN/EVE BUT CHCS ARE NOT GREAT ENOUGH TO
INCLUDE ATTM. WINDS WILL TRANSITION SOUTHERLY AFTER A WARM FRONT
LIFTS NORTH OF KGRI.
&&
.FIRE WEATHER...
ISSUED AT 453 AM CDT SUN SEP 8 2013
AS PREVIOUSLY DISCUSSED OVER THE PAST 24 HOURS...MONDAY CONTINUES
TO APPEAR A DECENT CANDIDATE FOR NEAR-CRITICAL TO POTENTIALLY
CRITICAL FIRE DANGER ACROSS PARTS OF THE CWA. ON SATURDAY...AREA
FIRE WEATHER MANAGERS DEEMED VEGETATIVE FUELS ACROSS OUR KS ZONES
TO BE DRY ENOUGH TO SUPPORT POSSIBLE HEADLINES...ALTHOUGH FUELS
ACROSS OUR NEBRASKA COUNTIES ARE STILL ASSUMED TO BE GREEN ENOUGH
TO PRECLUDE MAJOR ISSUES BARRING FURTHER INFORMATION. AS LONG AS
FUELS ARE DEEMED FAVORABLE...CRITICAL FIRE WEATHER THRESHOLDS
ACROSS THE GID CWA INCLUDE A COMBINATION OF RELATIVE HUMIDITY
AT/BELOW 20 PERCENT AND SUSTAINED WINDS/GUSTS OF 20 MPH/25 MPH FOR
3+ HOURS. AS THE FORECAST CURRENTLY STANDS...A DECENT OVERLAP OF
THESE WIND/RH PARAMETERS IS ANTICIPATED ACROSS MUCH OF THE
SOUTHWESTERN HALF OF THE CWA MONDAY AFTERNOON...AS INCREASING
SOUTHWESTERLY WINDS ALLOW HOT...DRY AIR TO OVERSPREAD THE AREA.
EVEN IN NORTHEAST PORTIONS OF THE CWA...RH VALUES ARE FORECAST TO
DROP BETWEEN 21-30 PERCENT...SO THERE COULD BE AT LEAST SOME
DEGREE OF FIRE DANGER THERE AS WELL DESPITE THE OVERALL GREENER
FUELS. GIVEN THAT MONDAY AFTERNOON IS STILL 30+ HOURS AWAY AND
STILL SUBJECT TO SOME FINE-TUNING...AND AFTER COORDINATION WITH
SURROUNDING OFFICES...WILL HOLD OFF ON ANY FIRE WEATHER HEADLINES
FOR KS ZONES AT THIS TIME...BUT WILL CONTINUE TO ADVERTISE NEAR-
CRITICAL TO POTENTIALLY CRITICAL CONDITIONS IN THE HAZARDOUS
WEATHER OUTLOOK.
&&
.CLIMATE...
ISSUED AT 453 AM CDT SUN SEP 8 2013
ALTHOUGH CURRENT FORECAST HIGH TEMPERATURES TODAY/MONDAY AT OUR
PRIMARY CLIMATE RECORD SITES GRAND ISLAND/HASTINGS ARE CURRENTLY
FORECAST SLIGHTLY SHY OF RECORDS...IT COULD BE A PRETTY CLOSE
CALL. THOSE RECORDS ARE AS FOLLOWS...
SUNDAY SEP. 8...GRAND ISLAND 101 IN 1931 AND 1928
HASTINGS 101 IN 1931
MONDAY SEP. 9...GRAND ISLAND 104 IN 1931
HASTINGS 102 IN 1919
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...FAY
LONG TERM...PFANNKUCH
AVIATION...FAY
FIRE WEATHER...PFANNKUCH
CLIMATE...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
453 AM CDT SUN SEP 8 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 453 AM CDT SUN SEP 8 2013
AN UPPER LEVEL RIDGE OF HIGH PRESSURE CONTINUES TO DOMINATE THE
WEATHER PATTERN ACROSS THE INTERIOR CONUS...RESULTING IN HOT
TEMPERATURES FOR EARLY SEPTEMBER...WELL ABOVE NORMAL. AT THE
SURFACE...LOW PRESSURE WAS CENTERED ALONG THE WY/NEB BORDER...WITH
A STALLED FRONTAL BOUNDARY EXTENDING EASTWARD ALONG THE NEB/KS
STATELINE. HIGH DPS IN THE UPPER 60S TO AROUND 70 HAVE POOLED NORTH
OF THE BOUNDARY AND IN PRESENCE OF THE LLVL MOISTURE...SOME PATCHY
FOG HAS DEVELOPED WITH THE LOWEST VSBYS SO FAR AROUND ONE OR TWO
MILES. WILL CONTINUE TO MONITOR VSBY TRENDS THRU THE PRE DAWN
HOURS AS MODELS ARE NOT IN AGREEMENT ON HOW SIGNIFICANT FOG WILL BE
...AND THE HRRR SUGGESTS POTENTIAL FOR DENSE FOG.
THE FRONTAL BOUNDARY ALONG THE NEB/KS STATELINE WILL LIFT NORTH AS A
WARM FRONT TODAY AND TEMPERATURES WILL BE TOASTY WITH READINGS
RISING WELL INTO THE 90S...AND OUR WESTERN/SOUTHERN ZONES WILL BE
EVEN WARMER WITH HIGHS IN THE 100 TO 105F RANGE. HEAT INDICES WILL
BE FAIRLY CLOSE OR JUST BELOW AMBIENT TEMPS AS DPS LOWER BEHIND
BOUNDARY...AND SHOULD REMAIN SHY OF HEAT ADVISORY CRITERIA.
CANNOT COMPLETELY RULE OUT THE POTENTIAL FOR AN ISOLATED
THUNDERSTORM THIS AFTERNOON/EVENING...GENERALLY NORTH OF INTERSTATE
80 AS THE WARM FRONTAL BOUNDARY LIFTS ACROSS. MODELS INDICATE
PRESENCE OF MID LEVEL WAA AND FRONTOGENESIS BETWEEN H85 AND H7 NORTH
OF I-80 AND DAYTIME HIGHS ARE RIGHT AROUND CONVECTIVE TEMPERATURES.
BOTH THE NAM/GFS INDICATE THE LIFT/FORCING...BUT ONLY THE 4KM SPC
WRF INDICATES DEVELOPMENT. THE CONVECTIVE POTENTIAL IS LIMITED WITH
CAPPING/WARM MID LEVEL TEMPS...BUT CANNOT RULE OUT AN ISOLATED CHC
AND HAVE ADDED SMALL POPS.
DRY AND MILD CONDITIONS ARE FORECAST LATE EVENING ON...WITH LOWS
AVERAGING IN THE UPPER 60S TO AROUND 70F.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 453 AM CDT SUN SEP 8 2013
THERE CONTINUES TO REMAIN A FAIRLY CONSISTENT FORECAST THEME
THROUGH THESE 6 DAYS...WITH MONDAY FEATURING THE FINALE OF A
MEMORABLE EARLY SEPTEMBER HOT SPELL...ALTHOUGH TUESDAY STILL LOOKS
PLENTY TOASTY AS WELL ACROSS ROUGHLY THE SOUTHEASTERN 1/3 OF THE
CWA WITH HIGHS BETWEEN 90-95. THEREAFTER...THE WED-SAT TIME FRAME
IS EXPECTED TO FEATURE HIGHS PREDOMINANTLY IN THE 80S...WHICH ON
SEVERAL DAYS WILL STILL BE A FEW DEGREES ABOVE NORMAL DESPITE
BEING MORE SEASONABLE. AS FOR SHOWER/THUNDERSTORM CHANCES...THERE
REMAINS AT LEAST A SLIGHT CHANCE MENTION IN THE FORECAST FOR AT
LEAST A PORTION OF THE OUTLOOK AREA DURING EVERY PERIOD FROM
MONDAY NIGHT THROUGH FRIDAY NIGHT...WITH SATURDAY VOID OF
MENTIONABLE POPS...AT LEAST FOR NOW. IF ANYTHING...UNCERTAINTY
CONTINUES TO GROW REGARDING WHICH OF THESE PERIODS MIGHT BE
FAVORED FOR MORE WIDESPREAD PRECIPITATION COVERAGE...SO FOR NOW
MOST OF THESE CHANCES CONTINUE TO BE HELD DOWN IN THE 20-30
PERCENT RANGE. AS DISCUSSED OVER THE PAST 24 HOURS...MONDAY COULD
POTENTIALLY FEATURE SOME OF THE HIGHEST FIRE DANGER THE LOCAL AREA
HAS SEEN THIS SUMMER...AND THESE CONCERNS ARE OUTLINED IN GREATER
DETAIL IN THE SEPARATE FIRE WEATHER SECTION BELOW.
STARTING WITH MONDAY/MONDAY NIGHT...THE LATEST 00Z/06Z MODELS ARE
IN GOOD AGREEMENT ON THE BIG PICTURE ALOFT...WITH THE LOCAL AREA
EXPERIENCING SOUTHWESTERLY FLOW ALOFT AS THE CENTER OF THE
EXPANSIVE RIDGE AXIS CURRENTLY PARKED OVERHEAD CONTINUES TO DRIFT
FARTHER AWAY INTO THE SOUTHEAST STATES...AS A PROGRESSIVE
SHORTWAVE TROUGH TRANSLATES ALONG THE U.S./CANADA BORDER FROM A
CENTRAL POSITION OVER NORTHERN MT AT SUNRISE MONDAY...TO NORTHERN
MN BY SUNRISE TUESDAY. IN RESPONSE...A MODEST COLD FRONT WILL
DRIFT SOUTHEASTWARD INTO THE CENTRAL PLAINS. DURING THE DAYTIME
MONDAY...THE CWA WILL REMAIN JUST AHEAD OF THIS COLD FRONT...WHICH
IS FORECAST TO ALIGN FROM NORTHEAST TO TO NORTH CENTRAL NEB BY
LATE AFTERNOON...BEFORE SLOWLY INFILTRATING MUCH OF THE
NORTHERN/CENTRAL CWA MONDAY NIGHT. THE DAYTIME HOURS SHOULD BE
ANOTHER HOT ONE AREA-WIDE...AS SUSTAINED SOUTH-SOUTHWEST WINDS
PICK UP TO AT LEAST 15-20 MPH WITH GUSTS 25+ MPH IN MOST
AREAS...EXCEPT FOR A BIT LIGHTER SPEEDS POSSIBLE IN FAR NORTHWEST
COUNTIES IN CLOSET PROXIMITY TO THE APPROACHING TROUGH AXIS. WITH
DEEP MIXING FORECAST TO AVERAGE UP TO AROUND 750 MILLIBARS OVER
MUCH OF THE CWA...ANTICIPATE DEWPOINTS TO FALL WELL DOWN INTO THE
50S DURING THE AFTERNOON...WITH 40S IN SEVERAL SOUTHWESTERN
COUNTIES. IN THEORY...THIS SETUP SHOULD SET THE STAGE FOR SOME OF
THE HOTTEST READINGS OF THIS ENTIRE HOT STRETCH...ESPECIALLY IN
CENTRAL/NORTHEAST COUNTIES...BUT SOMEWHAT ODDLY MET/MAV GUIDANCE
SUGGESTS HIGHS MONDAY WOULD BE A TOUCH COOLER THAN THOSE TODAY.
DESPITE THIS...HAVE KEPT FORECAST HIGHS AT LEAST A FEW DEGREES
ABOVE A GUIDANCE BLEND IN MOST AREAS...WITH ALL BUT THE FAR
NORTHERN CWA AIMED TO TOP OUT SOMEWHERE IN THE 98-103 RANGE...WITH
THE HIGHER END OF THIS RANGE IN FAR SOUTHERN/SOUTHWEST COUNTIES.
DUE TO THE LOWER DEWPOINTS...HEAT INDEX VALUES IN MOST AREAS ONLY
AVERAGE 95-100 DEGREES. AS FOR STORM CHANCES...MODELS VARY ON HOW
AGGRESSIVELY CONVECTION MAY TRY TO SLIP INTO OUR FAR NORTHWEST
ZONES MONDAY EVENING/NIGHT...WITH SOME BRINGING THEM JUST IN WHILE
OTHERS KEEP THEM JUST OUTSIDE. GIVEN THE SLOWING NATURE OF THE
SURFACE FRONT...HAVE BACKED OFF MON NIGHT POPS TO ONLY ABOUT THE
NORTHWESTERN 1/4 OF THE CWA...WHILE THE VAST MAJORITY OF THE CWA
STAYS DRY. ALTHOUGH ANY MARGINAL SEVERE THREAT DURING THE LATE
AFTERNOON/EVENING SHOULD LARGELY TARGET THE SANDHILLS REGION JUST
TO OUR NORTHWEST...SUPPOSE A STRONG TO MARGINALLY SEVERE STORM OR
TWO CANNOT BE RULED OUT SLIPPING INTO OUR AREA...WITH THE MAIN
THREAT BEING GUSTY WINDS DUE TO HIGH CLOUD BASES IN THE DEEPLY-
MIXED AIRMASS NEAR THE FRONT. SEVERE PARAMETERS ARE NOT ALL THAT
IMPRESSIVE...WITH THE GFS SUGGESTING EARLY EVENING CAPE AVERAGING
WELL UNDER 1000 J/KG...ALTHOUGH DEEP LAYER SHEAR ISN/T ALL THAT
POOR AROUND 30-40 KNOTS.
TUESDAY/TUES NIGHT...THE NORTHERN MN SHORTWAVE TROUGH QUICKLY
SLIDES EAST INTO SOUTHEAST CANADA...AND ALTHOUGH THE CWA SEES A
PERIOD OF DECENT UPPER JET ENTRANCE REGION LIFT AND ASSOCIATED MID
LEVEL FRONTOGENESIS...THE MAIN FORCING STEADILY SLIDES AWAY TO THE
NORTHEAST...ALLOWING THE SURFACE FRONT TO LOSE STEAM AND GENERALLY
STALL OUT WITHIN OR NEAR THE SOUTHERN EDGE OF THE CWA BY TUESDAY
AFTERNOON/NIGHT. THERE COULD BE A DECENT TEMP GRADIENT IN HIGHS
TUESDAY AFTERNOON...AND HAVE MADE LITTLE CHANGE...STILL AIMING FOR
LOW-MID 80S NORTHWEST TO LOW-MID 90S SOUTHEAST. IF ENOUGH
INSTABILITY BUILDS ALONG THE SURFACE BOUNDARY...COULD MAYBE SEE
SOME STRONG TO SEVERE NEAR-SURFACE BASED STORMS FLARE UP IN
SOUTHERN COUNTIES TUESDAY AFTERNOON/EVENING...WITH MORE ELEVATED
ACTIVITY DEVELOPING FARTHER NORTH AS THE NIGHT WEARS ON IN RESPONSE
TO MID-LEVEL THETA-E ADVECTION. EVEN ONLY 3 DAYS
AWAY...UNCERTAINTY IS VERY HIGH HERE...AND HAVE KEPT DAYTIME POPS
IN SLIGHT CHANCE RANGE...WITH A GREATER COVERAGE OF 30 POPS
TUESDAY NIGHT.
WEDNESDAY THROUGH FRIDAY NIGHT...THERE CONTINUES MULTIPLE...MAINLY
20-30 PERCENT POPS ACROSS ALL/MOST OF THE CWA...AND OBVIOUSLY A
LOT OF FINE-TUNING WILL NEED DONE HERE IN THE COMING DAYS. ON THE
LARGE SCALE ALOFT...THE LOCAL AREA SETS UP UNDER FAIRLY WEAK WEST-
SOUTHWEST FLOW ALOFT...IN THE WAKE OF A DEEPENING TROUGH MIGRATING
ACROSS SOUTHEAST CANADA/THE NORTHEAST CONUS...AND ALONG THE
NORTHERN PERIPHERY OF AN EXPANSIVE SOUTHERN CONUS RIDGE
AXIS...WHICH INSTEAD OF BEING OVERHEAD AS THE CURRENT ONE
IS...THIS TIME SETS UP FARTHER SOUTH MORE OVER OK/TX. WITH THE
REMNANT...GENERALLY EAST-WEST SURFACE FRONT REMAINING IN PLACE
NEAR OR OVER THE CWA DURING THE TIME...AND WITH THE AREA BEING
PRONE TO MAINLY NOCTURNAL INCREASES IN THETA-E ADVECTION IN THE
850-700MB LAYER...THERE COULD BE SEVERAL ROUNDS OF
SHOWERS/STORMS...AND MAYBE EVEN AN OCCASIONAL SEVERE THREAT. TEMP-
WISE...LITTLE CHANGE FROM PREVIOUS WITH HIGHS GENERALLY LOW-MID
80S MOST AREAS...ALTHOUGH SOME 70S NOT OUT OF THE QUESTION.
SATURDAY...HAVE LEFT OUT POPS FOR NOW DUE TO INCREASING MODEL
VARIABILITY AND UNCERTAINTY AT THIS TIME RANGE..BUT DRY IS NO
GUARANTEE...WITH THE LOCAL AREA REMAINING NORTH OF THE SOUTHERN
PLAINS RIDGE AND POSSIBLY IN THE PATH OF SOME LOW AMPLITUDE
DISTURBANCES BRUSHING BY THROUGH THE NORTHERN PLAINS. WILL CALL
FOR MAINLY MID 80S IN NEB ZONES AND UPPER 80S IN KS.
&&
.AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1231 AM CDT SUN SEP 8 2013
A FRONTAL BOUNDARY HAS STALLED SOUTH OF THE TERMINAL AND AS
MOISTURE POOLS IN THE VICINITY OF THE BOUNDARY...THERE IS AN
OUTSIDE CHANCE FOR AN MVFR VSBY IN BR DURING THE PRE DAWN HOURS.
HAVE KEPT VSBYS AT VFR FOR NOW...BUT WILL MONITOR. THE FRONT WILL
LIFT TO THE NORTH AS WARM FRONT DURING THE DAY ON SUNDAY...WITH
THE CURRENT LIGHT AND VARIABLE WINDS BECOMING SOUTHERLY DURING THE
AFTN. CLOUDS ARE EXPECTED TO REMAIN AT VFR LEVELS.
&&
.FIRE WEATHER...
ISSUED AT 453 AM CDT SUN SEP 8 2013
AS PREVIOUSLY DISCUSSED OVER THE PAST 24 HOURS...MONDAY CONTINUES
TO APPEAR A DECENT CANDIDATE FOR NEAR-CRITICAL TO POTENTIALLY
CRITICAL FIRE DANGER ACROSS PARTS OF THE CWA. ON SATURDAY...AREA
FIRE WEATHER MANAGERS DEEMED VEGETATIVE FUELS ACROSS OUR KS ZONES
TO BE DRY ENOUGH TO SUPPORT POSSIBLE HEADLINES...ALTHOUGH FUELS
ACROSS OUR NEBRASKA COUNTIES ARE STILL ASSUMED TO BE GREEN ENOUGH
TO PRECLUDE MAJOR ISSUES BARRING FURTHER INFORMATION. AS LONG AS
FUELS ARE DEEMED FAVORABLE...CRITICAL FIRE WEATHER THRESHOLDS
ACROSS THE GID CWA INCLUDE A COMBINATION OF RELATIVE HUMIDITY
AT/BELOW 20 PERCENT AND SUSTAINED WINDS/GUSTS OF 20 MPH/25 MPH FOR
3+ HOURS. AS THE FORECAST CURRENTLY STANDS...A DECENT OVERLAP OF
THESE WIND/RH PARAMETERS IS ANTICIPATED ACROSS MUCH OF THE
SOUTHWESTERN HALF OF THE CWA MONDAY AFTERNOON...AS INCREASING
SOUTHWESTERLY WINDS ALLOW HOT...DRY AIR TO OVERSPREAD THE AREA.
EVEN IN NORTHEAST PORTIONS OF THE CWA...RH VALUES ARE FORECAST TO
DROP BETWEEN 21-30 PERCENT...SO THERE COULD BE AT LEAST SOME
DEGREE OF FIRE DANGER THERE AS WELL DESPITE THE OVERALL GREENER
FUELS. GIVEN THAT MONDAY AFTERNOON IS STILL 30+ HOURS AWAY AND
STILL SUBJECT TO SOME FINE-TUNING...AND AFTER COORDINATION WITH
SURROUNDING OFFICES...WILL HOLD OFF ON ANY FIRE WEATHER HEADLINES
FOR KS ZONES AT THIS TIME...BUT WILL CONTINUE TO ADVERTISE NEAR-
CRITICAL TO POTENTIALLY CRITICAL CONDITIONS IN THE HAZARDOUS
WEATHER OUTLOOK.
&&
.CLIMATE...
ISSUED AT 453 AM CDT SUN SEP 8 2013
ALTHOUGH CURRENT FORECAST HIGH TEMPERATURES TODAY/MONDAY AT OUR
PRIMARY CLIMATE RECORD SITES GRAND ISLAND/HASTINGS ARE CURRENTLY
FORECAST SLIGHTLY SHY OF RECORDS...IT COULD BE A PRETTY CLOSE
CALL. THOSE RECORDS ARE AS FOLLOWS...
SUNDAY SEP. 8...GRAND ISLAND 101 IN 1931 AND 1928
HASTINGS 101 IN 1931
MONDAY SEP. 9...GRAND ISLAND 104 IN 1931
HASTINGS 102 IN 1919
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...FAY
LONG TERM...PFANNKUCH
AVIATION...FAY
FIRE WEATHER...PFANNKUCH
CLIMATE...PFANNKUCH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1045 AM EDT SUN SEP 8 2013
.SYNOPSIS...
HIGH PRESSURE OVER THE AREA WILL WEAKEN AND SHIFT TO OUR SOUTH
TODAY. A DRY COLD FRONT WILL APPROACH FROM THE NORTH LATE TODAY...
THEN MOVE SOUTHWARD THROUGH NC TONIGHT. ANOTHER HIGH PRESSURE AREA
WILL BUILD INTO THE REGION FROM THE NORTH FOR MONDAY AND TUESDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 1045 AM SUNDAY...
REST OF TODAY: THE MOST STRIKING CHANGE TO THE FORECAST WILL BE AN
INCREASE IN THE AMOUNT OF SUNSHINE... PARTICULARLY OUTSIDE OF THE
TRIAD REGION. LATEST SURFACE MAP SHOWS A WEAK PRESSURE/WIND PATTERN
OVER THE REGION... FEATURING A SURFACE TROUGH THROUGH THE PIEDMONT
AND YESTERDAY`S HIGH PRESSURE AREA SLIDING FURTHER TO OUR SW. THE
SURFACE COLD FRONT NOW STRETCHING FROM AROUND BOSTON TO JUST NORTH
OF THE OH RIVER... MAKING GOOD SOUTHWARD PROGRESS AS IT IS PUSHED BY
COOL DENSE HIGH PRESSURE TO THE NORTH. WIDESPREAD MID CLOUDS TO OUR
NORTH EARLIER THIS MORNING... ACROSS WV/VA/MD/DE/NJ/PA SHORTLY
BEFORE DAYBREAK... HAVE ALMOST COMPLETELY VANISHED AS THEY
ENCOUNTERED THE DRY/STABLE AIR AND DIFFLUENT FLOW OVER NC. RAP MODEL
SOUNDINGS SHOW A FEW MID CLOUDS DRIFTING OVER THE FORECAST AREA THIS
AFTERNOON... BUT THIS APPEARS TO BE SHORT-LIVED WITH MAINLY
SCATTERED CLOUDS... AND MOST OF THE AREA SHOULD SEE MOSTLY SUNNY
SKIES FOR THE MAJORITY OF THE DAY. THE EXCEPTION WILL BE IN THE NW
CWA WHERE MODELS... UPSTREAM SOUNDINGS... AND SATELLITE TRENDS
SUGGEST THAT THE COVERAGE OF MID CLOUDS WILL BE A LITTLE BETTER...
LEADING TO PARTLY CLOUDY SKIES. SEVERAL CONVECTION-ALLOWING MODELS
DEPICT A FEW SPRINKLES MAKING IT INTO THE FOOTHILLS LATE THIS
AFTERNOON... BUT BASED ON THE GENERALLY DOWNSLOPE FLOW AND LACK OF
LOW LEVEL MOISTURE... BELIEVE THESE WILL HOLD JUST NW OF THE CWA.
THICKNESSES AND STATISTICAL GUIDANCE SUPPORT FORECAST HIGHS OF
86-91. -GIH
TONIGHT AND MONDAY:
THE AFOREMENTIONED COLD FRONT WILL PROGRESS SOUTHWARD INTO CENTRAL
NC TONIGHT WILL LITTLE FANFARE... OTHER THAN AN INCREASE IN CLOUD
COVER. THE FRONT IS EXPECTED TO WEAKEN AS IT MOVES THROUGH THE AREA
TONIGHT... BEFORE IT STALLS/DISSIPATES NEAR THE NC/SC BORDER ON
MONDAY. SURFACE HIGH PRESSURE WILL BUILD INTO THE AREA BEHIND THE
FRONT. HOWEVER... AS THE SURFACE HIGH CENTERED OVER THE NORTHERN
MID-ATLANTIC/NORTHEASTERN U.S. MONDAY MORNING SHIFTS EASTWARD AND
OFFSHORE ON MONDAY AFTERNOON... A LIGHT EASTERLY LOW LEVEL FLOW WILL
DEVELOP ACROSS CENTRAL NC. THIS WILL ALLOW LOW LEVEL MOISTURE TO
INCREASE... ALONG WITH POSSIBLY A FEW SHOWERS ACROSS OUR COASTAL
PLAIN COUNTIES IN THE AFTERNOON. HOWEVER... GIVEN INSTABILITY WILL
REMAIN WEAK STILL... WHILE MID LEVEL TEMPS ACTUALLY INCREASE A BIT
AS THE AFOREMENTIONED MID LEVEL RIDGES BEGINS TO BUILD EASTWARD AND
EXTENDS INTO OUR AREA... WILL ONLY KEEP A SLIGHT CHANCE OF SHOWERS
IN THE FORECAST ALONG AND TO THE EAST OF THE I-95 CORRIDOR.
LOW TEMPS MONDAY MORNING ARE EXPECTED TO BE IN THE MID TO UPPER
60S... THANKS TO THE INCREASE IN CLOUD COVER. HIGH TEMPS ON MONDAY
WILL BE TEMPERED BACK A BIT WITH THE EASTERLY LOW LEVEL FLOW. THIS
YIELDS HIGH TEMPS IN THE MID TO UPPER 80S.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 300 AM SUNDAY...
STRONG UPPER ANTI-CYCLONE OVER THE CENTRAL U.S. MIGRATES EWD AND
SETTLES OVER THE SOUTHERN APPALACHIANS MONDAY NIGHT THROUGH
WEDNESDAY. THE RISING HEIGHTS AND ASSOCIATED WARMING ALOFT WILL ACT
TO SUPPRESS THE ABILITY FOR CONVECTION TO FORM TUESDAY...AND JUST A
SLIGHT CHANCE OF AFTERNOON CONVECTION OVER THE NW PIEDMONT/TRIAD
REGION WEDNESDAY AFTERNOON. THE PRESENCE OF THE RIDGE AXIS ALOFT AND
THE SFC HIGH ANCHORED OFFSHORE WILL CAUSE VERY WARM/HOT CONDITIONS
TUESDAY AND WEDNESDAY. AFTERNOON THICKNESS PROJECTED TO REACH INTO
THE 1420-1425M RANGE...10-15M ABOVE NORMAL. THIS SUGGEST MAX TEMPS
TUESDAY IN THE MID-UPR 80S TUESDAY AND UPR 80S-AROUND 90 WEDNESDAY.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 300 AM SUNDAY...
THURSDAY...A FAIRLY STOUT S/W IN THE NORTHERN STREAM WILL CROSS THE
GREAT LAKES THU. THIS FEATURE WILL ACT TO WEAKEN THE UPPER LEVEL
RIDGE OVER THE CAROLINAS AND CAUSE THE ANTI-CYCLONE TO RETROGRADE
BACK TOWARD THE MS RIVER VALLEY. THE FALLING HEIGHTS WILL AID TO
SHARPEN THE PIEDMONT SFC TROUGH BY THU AFTERNOON. THIS MAY SUPPORT
THE DEVELOPMENT OF ISOLATED-SCATTERED CONVECTION OVER THE NW
PIEDMONT THOUGH MOISTURE AVAILABILITY STILL IN QUESTION. IT WILL
REMAIN VERY WARM THANKS TO THE SW LOW LEVEL FLOW. THICKNESSES
THURSDAY AFTERNOON REMAIN IN THE 1420S. MAX TEMPS IN THE UPPER
80S-AROUND 90 WILL ONCE AGAIN BE THE NORM.
THURSDAY NIGHT THROUGH FRIDAY...THE NORTHERN STREAM S/W WILL
CONTINUE MOVING E-SE AND RESULT IN LOWERING UPR LEVEL HEIGHTS ACROSS
THE CAROLINAS THU NIGHT INTO FRIDAY. THE ATTENDANT SFC FRONT WILL BE
ENTERING OUR FORECAST AREA BY FRIDAY MORNING THEN SLIDE SEWD AS THE
S/W CROSSES NEW ENGLAND AND EXISTS OFFSHORE. SINCE BEST UPPER LEVEL
SUPPORT WELL TO OUR NORTH AND MOISTURE TRANSPORT MARGINAL DUE TO
WESTERLY FLOW AHEAD OF THE SYSTEM...CHANCES FOR SHOWERS AND ISOLATED
T-STORM APPEAR TO BE NO HIGHER THAN 30-40 PERCENT THU NIGHT INTO
FRIDAY WITH THE BETTER CHANCES FOR SHOWERS/T-STORMS LIKELY CONFINED
TO THE SOUTHERN AND EASTERN COUNTIES BY FRIDAY AFTERNOON. GFS STILL
APPEARS A LITTLE TOO FAST IN MOVING THE SYSTEM THROUGH CONSIDERING
THE BEST PUSH/EWD ACCELERATION WILL BE ACROSS NEW ENGLAND AND THE
NORTHERN MID ATLANTIC. EXPECTED SHOWER COVERAGE AND ASSOCIATED CLOUD
COVER WILL RESULT IN SLIGHTLY COOLER TEMPS THOUGH DEWPOINTS WELL
INTO THE 60S TO NEAR 70 WILL STILL MAKE IT FEEL VERY WARM. MAX TEMPS
IN THE LOW-MID 80S.
FRIDAY NIGHT INTO SATURDAY...LONG TERM MODEL GUIDANCE STILL
SUGGESTING THE ADVECTION OF COOLER AND DRIER AIR INTO CENTRAL NC
FOR THE START OF THE WEEKEND. MODEL THICKNESSES DROP INTO THE 1360S
BY SATURDAY MORNING WITH 1350S POSSIBLE BY NEXT SUNDAY MORNING.
CONSIDERING THE ORIGINS OF THE CANADIAN HIGH BUILDING INTO OUR
REGION...THIS SEEMS PLAUSIBLE. MAX TEMPS SATURDAY MAY REMAIN BELOW
80 DEGREES MOST SPOTS.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AS OF 640 AM SUNDAY...
24 HOUR TAF PERIOD:
VFR CONDITIONS ARE GENERALLY EXPECTED TO PREVAIL ACROSS THE AREA AS
DRY COLD FRONT APPROACHES THE REGION FROM THE NORTH TODAY. THE COLD
FRONT IS EXPECTED TO SLOWLY CROSS CENTRAL NC TONIGHT. IF ANY MVFR
FOG DEVELOPS THIS MORNING AT KRWI IT WILL MIX OUT QUICKLY WITH
DIURNAL MIXING AND SHOULD BE GONE BY 12Z AT THE LATEST. OTHERWISE...
WE WILL SEE MID AND HIGH LEVEL CLOUD COVER ON THE INCREASE THIS
MORNING AS A WEAK DISTURBANCE ALOFT MOVES ACROSS THE AREA. THE
AFOREMENTIONED SURFACE FRONT IS NOT EXPECTED TO MOVE INTO THE AREA
UNTIL LATE TONIGHT. HOWEVER... OUTSIDE OF AN INCREASE IN VFR
CLOUDS... THE FRONT WILL COME THROUGH WITH LITTLE FANFARE AND STALL
NEAR THE NC/SC BORDER AROUND 12Z MONDAY.
OUTLOOK:
PRE-DAWN/MORNING SUB-VFR CONDITIONS WILL BE POSSIBLE EACH MORNING...
ALTHOUGH CONFIDENCE IS VERY LOW FOR ANY WIDESPREAD SUB-VFR
CONDITIONS. OTHERWISE... VFR CONDITIONS ARE EXPECTED... WITH
GENERALLY DRY CONDITIONS (VERY SMALL CHANCE OF A AFTERNOON/EVENING
SHOWER OR STORM EACH DAY AS WELL... BEST CHANCE ON WEDNESDAY AND
THURSDAY AT KGSO/KINT).
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BSD/HARTFIELD
NEAR TERM...HARTFIELD/BSD
SHORT TERM...WSS
LONG TERM...WSS
AVIATION...BSD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1014 AM CDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 1013 AM CDT SUN SEP 8 2013
QUITE A FEW CHANGES TO THE MORNING UPDATE...MAINLY CENTERED AROUND
CURRENT SHOWER ACTIVITY AND ANTICIPATED DEVELOPMENT OVER THE NEXT
FEW HOURS. CURRENTLY...SHOWERS OVER SOUTH CENTRAL NORTH DAKOTA
CONTINUE TO TRANSLATE EAST. OF THE SHORT TERM MODELS...THE 12 UTC
HRRR SEEMED TO HAVE THE BEST HANDLE ON THE CURRENT SHOWERS. THUS
UTILIZED THE HRRR FOR POP/QPF FORECAST THROUGH THE EARLY
AFTERNOON. THIS RESULTED IN LOWERING OF POPS ACROSS THE NORTH
WHERE LITTLE IS GOING ON...AND INCREASING POPS OVER THE SOUTH
CENTRAL. ALSO LOWERED QPF AMOUNTS THROUGH MUCH OF THE DAY AS RAIN
AMOUNTS HAVE BEEN LIGHT IN THIS AREA OF HIGH BASED SHOWERS. DO NOT
EXPECT HIGHER QPF AMOUNTS UNTIL WE GET SOME CONVECTIVE ELEMENTS
INVOLVED. WITH THE EXTENSIVE CLOUD COVER...ALSO LOWERED
TEMPERATURES A FEW DEGREES MOST AREAS. THINK THE BETTER
PRECIPITATION CHANCES WILL ARRIVE TONIGHT BUT DID BEGIN TO
INCREASE POPS ACROSS THE WEST LATER THIS AFTERNOON.
UPDATE ISSUED AT 638 AM CDT SUN SEP 8 2013
COPIOUS AMOUNTS OF MOISTURE CONTINUE TO OVERSPREAD WESTERN AND
CENTRAL NORTH DAKOTA THIS MORNING AHEAD OF AN APPROACHING
SHORTWAVE. THE LATEST RAP PROGS PWATS GREATER THAN 1.5 INCHES OVER
AREAS SOUTH OF I-94 THIS MORNING. THIS IS ABOUT 200 PERCENT OF
NORMAL FOR SEPTEMBER. GIVEN THE SATURATED ENVIRONMENT...THINK
THE CURRENT FLASH FLOOD WATCH LOOKS GOOD FOR TODAY AND TONIGHT.
NO MAJOR UPDATES WERE REQUIRED FOR THIS UPDATE. ONLY MODIFIED THE
HOURLY TEMP/DEWPOINT/WIND GRIDS BASED ON CURRENT OBS/TRENDS. THE
UPDATED PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 415 AM CDT SUN SEP 8 2013
FORECAST CHALLENGES/HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE
THE COVERAGE AND AMOUNT OF PRECIPITATION NOW THROUGH TONIGHT
ALONG WITH ANOTHER ROUND OF SEVERE WEATHER.
CURRENTLY...UPPER LEVEL RIDGE AXIS CENTERED ACROSS THE DAKOTAS
THIS MORNING. CONVECTION CONTINUES TO BE VIGOROUS FROM ACROSS
SOUTHWEST AND SOUTH CENTRAL NORTH DAKOTA...INTO SOUTH DAKOTA AND
WEST ACROSS SOUTHEAST MONTANA ALONG AN INSTABILITY AXIS AND IN THE
VICINITY OF A LOW LEVEL JET. AT THIS TIME STORMS ARE NON-
SEVERE...DUE IN PART TO RELATIVELY WEAK MID LEVEL LAPSE RATES.
ADDITIONAL SHOWERS/T-STORMS DEVELOPING OVER NORTHEAST MONTANA AND
EAST OVER NORTH CENTRAL AND NORTHEASTERN NORTH DAKOTA.
EXPECT THE CONVECTION OVER MONTANA TO SHIFT NORTH AND EAST INTO
WESTERN AND PORTIONS OF CENTRAL NORTH DAKOTA THIS MORNING AS A
POTENT LEAD S/WV IMPULSE NOW LIFTING ACROSS WYOMING MOVES INTO
EASTERN MONTANA 12-18Z...AND AS THE LLJ BECOMES MORE FOCUSED OVER
WESTERN ND BY 12Z AND SHIFTS EAST INTO CENTRAL ND LATER THIS
MORNING.
SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS MUCH OF THE REGION
TODAY INTO TONIGHT AS ADDITIONAL MID LEVEL WAVES LIFT NORTHEAST
ACROSS THE NORTHERN PLAINS...IN ADVANCE OF THE UPPER LOW (NOW
OVER NORTHERN IDAHO) AS IT TRACKS EAST ACROSS NORTHERN MONTANA. AT
THIS TIME EXPECT THE HEAVIER PRECIPITATION FROM THE AFTERNOON INTO
THE EVENING HOURS ACROSS NORTH DAKOTA WHEN DIFFLUENT FLOW ALOFT
LINKS TO STRONG THERMAL LIFT NORTH OF AN AREA OF LOW PRESSURE
ADVANCING NORTH AND EAST ACROSS SOUTH DAKOTA. THE STRONG SYNOPTIC
FORCING WILL COINCIDE WITH PLENTY OF INSTABILITY AND SHEAR TO
TRIGGER AT LEAST A FEW SEVERE STORMS THROUGH THE PERIOD.
IN ADDITION TO THE FORCING AND SEVERE PARAMETERS...MOISTURE
CONTINUES TO BE PUMPED FROM THE GULF OF MEXICO AROUND THE
SUBTROPICAL RIDGE INTO THE NORTHERN PLAINS. SURFACE TO 300MB
PRECIPITABLE WATER VALUES ARE CURRENTLY OVER 200 PERCENT OF NORMAL
FOR THIS TIME OF YEAR...AND ARE EXPECTED TO INCREASE TO NEAR 2
INCHES TODAY EXCEEDING THE MAXIMUM OBSERVED. THUS ANY STORMS WILL
HAVE THE POTENTIAL TO BE HEAVY RAINERS...SO WE HAVE EXTENDED THE
FLASH FLOOD WATCH THROUGH THIS SUNDAY NIGHT...AND EXPANDED THE
AERIAL COVERAGE TO INCLUDE ALL OF WEST AND CENTRAL NORTH DAKOTA.
ESPECIALLY PRONE TO FLASH FLOODING WILL BE PORTIONS OF WESTERN AND
SOUTHERN NORTH DAKOTA WHICH ALREADY SAW RAINFALL AMOUNTS UP TO
THREE INCHES THE PAST 12-24 HOURS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 415 AM CDT SUN SEP 8 2013
THE MEDIUM RANGE MODELS ARE RELATIVELY SLOWER WITH THE PROGRESSION
OF AN UPPER LEVEL LOW ACROSS NORTH DAKOTA MONDAY. THE LATEST
GUIDANCE NOW PIVOTS THE UPPER TROUGH AXIS ACROSS NORTH DAKOTA
MONDAY NIGHT (INSTEAD OF MONDAY AS GUIDANCE 24 HOURS AGO PROGGED).
AS A RESULT...KEPT CHANCE POPS IN FOR MONDAY...THEN FORECAST A
DECREASING POP TREND FROM SOUTHWEST TO NORTHEAST AS SUBSIDENCE
FILTERS IN BEHIND THE TROUGH AXIS MONDAY NIGHT. LINGERING SLIGHT
CHANCE POPS ARE FORECAST FOR BOTTINEAU...ROLETTE...AND PIERCE
COUNTIES TUESDAY MORNING. HOWEVER...LITTLE IMPACT IS EXPECTED.
DRY CONDITIONS ARE THEN EXPECTED AREAWIDE TUESDAY AFTERNOON THROUGH
FRIDAY AS UPPER LEVEL RIDGING BUILDS OVER THE NORTHERN ROCKIES AND
INTO THE NORTHERN PLAINS. ABOVE NORMAL TEMPERATURES ARE EXPECTED TO
CONTINUE THROUGH THE REMAINDER OF THE WORK WEEK.
ANOTHER ROUND OF PRECIPITATION IS FORECAST FOR SATURDAY AS AN UPPER
LEVEL SHORTWAVE EMANATING FROM THE ROCKIES IS PROGGED TO LIFT INTO
WESTERN NORTH DAKOTA. NOT REAL CONFIDENT WITH THE TIMING OF THIS
FEATURE AS THE MEDIUM RANGE MODELS HAVE RECENTLY BEEN STRUGGLING
WITH SHORTWAVE TIMING ISSUES. WILL CONTINUE TO MONITOR AND MAKE
ADJUSTMENTS AS NEEDED.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1013 AM CDT SUN SEP 8 2013
AREA OF IFR CEILINGS AT KDIK HAS DISSIPATES. THUS VFR CONDITIONS
AT ALL BUT KISN...WHERE MVFR CEILINGS REMAIN. CEILINGS AT KISN
SHOULD LIFT TO VFR BY THE 18Z TAF ISSUANCE. EXPECT VFR CONDITIONS
THEN TO BEGIN THE TAF PERIOD WITH SCATTERED SHOWERS. SHOWER AND
THUNDERSTORM CHANCES WILL INCREASE PRECIPITATION CHANCES WILL
INCREASE FROM WEST TO EAST AGAIN LATER THIS AFTERNOON AND TONIGHT
WITH ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS...LASTING INTO
MONDAY MORNING ACROSS THE EAST.
&&
.HYDROLOGY...
ISSUED AT 415 AM CDT SUN SEP 8 2013
AS MENTIONED ABOVE IN THE SHORT TERM SECTION...HAVE EXPANDED AND
EXTENDED THE FLASH FLOOD WATCH TO INCLUDE ALL OF WESTERN AND
CENTRAL NORTH DAKOTA THROUGH TONIGHT. VERY HIGH ATMOSPHERIC
MOISTURE WILL LINE UP WITH FAVORABLE INSTABILITY AND SYNOPTIC
FORCING TO WARRANT THIS CHANGE. MODELS ARE PROJECTING PWAT VALUES
EXCEEDING THE MAXIMUM OBSERVED FOR THIS TIME OF THE SEASON...NEAR 2
INCHES ACROSS MUCH OF THE REGION.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH MONDAY MORNING FOR NDZ001>005-009>013-
017>023-025-031>037-040>048-050-051.
&&
$$
UPDATE...TWH
SHORT TERM...NH
LONG TERM...TM
AVIATION...TWH
HYDROLOGY...NH
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1004 AM CDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 1004 AM CDT SUN SEP 8 2013
FORECAST CONFIDENCE IS LOW AS MODELS HAVE PERFORMED POORLY WITH
ONGOING PRECIPITATION THIS MORNING. WILL FOLLOW THE HRRR FOR THE
MORNING UPDATE...WHICH BEST REFLECTS REALITY.
AREA OF MODERATE SHOWERS WITH ISOLATED EMBEDDED THUNDER STRETCHES
FROM NORTH OF ST. CLOUD TO JUST SOUTH OF GRAND FORKS AND IS IN AN
AREA OF ENHANCED 300 HPA DIVERGENCE AND 850 HPA FRONTOGENESIS.
HRRR SUGGESTS THIS CONVECTION WILL CONTINUE EASTWARD AND DISSIPATE
BY EARLY AFTERNOON. UPDATED POPS TO REFLECT THIS THINKING. ANOTHER
AREA OF SHOWERS STRETCHES FROM SOUTHWEST OF BISMARCK TO EAST OF
ABERDEEN. HRRR SHOWS THIS PRECIPITATION ALSO WEAKENING AS IT MOVES
EAST. HOWEVER...AM NOTICING SOME REDEVELOPMENT ACROSS THE SOUTHERN
VALLEY AS A REMNANT MCV EVIDENT IN RADAR REFLECTIVITY MOVES INTO
THE ND/SD/MN BORDER REGION. WILL NEED TO WATCH THIS FOR THE NEXT
UPDATE...BUT DO NOT ANTICIPATE ANY STRONGER STORMS WITH INSTABILITY
MAXIMIZED FARTHER SOUTH ACROSS WESTERN SD.
OVERALL...ONCE BAND OF SHOWERS/STORMS MOVES OUT OF WEST CENTRAL
MN...THINK THUNDERSTORM COVERAGE WILL BE SCATTERED FOR THE REST
OF THE MORNING AND AFTERNOON AS THE PRIMARY FORCING REMAINS WEST
OF THE FORECAST AREA. ATTENTION TONIGHT WILL TURN TO FLOODING AND
SEVERE POTENTIAL. UPDATED POPS AND WX THOUGH 00 UTC AND ALSO
DECREASED TEMPERATURES A FEW DEGREES WITH PERSISTENT CLOUD COVER.
AFTERNOON HIGHS WILL REACH THE UPPER 60S ALONG THE INTERNATIONAL
BORDER TO THE UPPER 70S ALONG THE SD STATE LINE.
UPDATE ISSUED AT 659 AM CDT SUN SEP 8 2013
VERY COMPLEX PRECIP PATTERN THIS MORNING. NO MODEL HANDLING IT
WELL SO GOING OFF CURRENT RADAR AND ADJUSTING FOR A FEW HOURS
AHEAD FOR IMMEDIATE UPDATES. MAIN MCS DWINDLED IN SE ND/NE SD AS
EXPECTED...BUT OUT AHEAD OF IT SOME CONVECTION FORMED IN THE FARGO
AREA PRODUCING UP TO 1 INCH OF RAIN QUICKLY. THIS CLUSTER MOVING
EAST INTO DTL-FFM AREAS. DID UP POPS REST OF THIS MORNING INTO
WCNTRL MN FOR THIS. OTHERWISE MORE SCATTERED LIGHT ACTIVITY
NORTHWARD INTO THE NRN VALLEY. WOULD APPEAR THIS AFTN TO SEE
SCATTERED ACTIVITY BUT MOST OF THE FOCUS WILL WAIT TIL OVERNIGHT.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 324 AM CDT SUN SEP 8 2013
THREAT FOR HEAVY RAIN TONIGHT IS THERE...BUT WHERE AND HOW MUCH IS
THE MAIN QUESTION. MODEL QPF HAS BEEN RATHER POOR LATELY SO
CONFIDENCE IN AMOUNTS AND EXACT PLACEMENT POOR.
CURRENTLY...HAVE REMAINS OF TSTM COMPLEX THAT WAS IN SW/SCNTRL
ND/NRN SD MOVING EAST SLOWLY AND WEAKENING AS IT ENTERS THE
ABERDEEN-OAKES AREA. BUT HRRR DOES TAKE SOME SHOWERS EAST ACROSS
THE SD/ND BORDER REGION INTO WCNTRL THIS MORNING SO INCLUDED POPS
FOR THIS. HOWEVER IT IS RUNNING INTO QUITE A BIT OF DRY AIR SOON
AND SHOULD START TO REALLY WEAKEN.
MODELS 12Z SAT AND 00Z SUN INDICATED TSTM COMPLEX IN WCNTRL OR NW
ND AT THIS TIME AND INSTEAD DEVELOPMENT HAS BEEN FARTHER SOUTH IN
A NARROW 850 MB LOW LEVEL JET ZONE IN THE DICKINSON-HETTINGER-
BOWMAN AREA OF ND INTO NW SD. THUS PREV FCST IDEA OF LIKELY POPS
SPREADING INTO DVL BASIN THIS MORNING SEEMS A BIT OFF AND REDUCED
POPS TO HIGH CHANCE. RADAR HAS BEEN SHOWING SOME VERY LIGHT
SHOWERS FROM THE MID LEVEL CLOUD COVER MOVING INTO DVL BASIN BUT
WIDESPREAD RAINFALL NOT ANTICIPATED AS FOCUS WILL CONTINUE TO BE
MORE IN SW ND AND THEN INTO CNTRL ND TODAY WITH LOW LEVEL 850 MB
JET AND MOISTURE.
TONIGHT IS THE MAIN ACTION AS SHORT WAVE LIFTS NORTHEAST FROM
MONTANA TROUGH INTO WRN ND AND SFC LOW IS STILL FCST TO TRACK FROM
WRN SD INTO FAR NE SD/SE ND BY 12Z MON. ALL INDICATIONS STILL
FAVOR A LARGE TSTM COMPLEX NORTHWEST OF SFC LOW FROM SW-CNTRL INTO
NE ND/FAR NW MN/SRN MANITOBA OVERNIGHT INTO MONDAY MORNING. KEPT
IDEA OF HVY RAIN MENTIONED IN GRIDDS AND CATEGORICAL POPS MAINLY
NORTH OF A VALLEY CITY-FARGO-BEMIDJI AREAS. GFS IS QUITE STRONG
WITH LOW LEVEL JET (40 KTS) AND HAS MAX 850 INSTABILITY GRADIENT IN
SE-ECNTRL ND-WCNTRL MN 09Z-12Z MON PERIOD AND THUS IDEA OF
ELEVATED SVR VERY POSSIBLE ALONG SRN EDGE OF ANY MCS. FOR RAINFALL
PWATS OF 2 INCHES AT 12Z MON WOULD ARGUE FOR WIDESPREAD 1-2 INCH
RAIN POTENTIAL IN MCS AREA WITH LOCALLY HEAVIER AMOUNTS.
CONSIDERING PAST 60-90 DAYS HAVE BEEN VERY DRY IN OUR REGION RAIN
WILL SOAK INTO THE GROUND WITH RUNOFF MORE LIMITED TO CITY-URBAN
AREAS. AND WITH STILL UNCERTAINTY DUE TO POOR MODEL QPF
PERFORMANCES OF LATE AND THE FACT THAT MAIN RAIN IS TONIGHT HELD
OFF ON ANY FLASH FLOOD WATCHES. BUT SOME MAY BE NEEDED ONCE HVY
RAIN AREA CAN BE PEGGED BETTER.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 324 AM CDT SUN SEP 8 2013
500 MB UPPER TROUGH TO MOVE OVER MANITOBA/NE ND/NW MN MON NIGHT-
TUES AND THUS WILL LEAVE IN LOW POPS FOR THIS.
WEDNESDAY-SATURDAY...BROAD CANADIAN SFC HIGH PRESSURE WILL DROP FROM
CENTRAL CANADA INTO THE GREAT LAKES MID TO LATE WEEK WITH NORTHWEST
FLOW ALOFT...KEEPING THE AREA DRY. MORE SEASONABLE HIGH TEMPS IN
THE 60S TO LOW 70S ARE EXPECTED BY THURSDAY/FRIDAY. THE COOLEST
NIGHT DURING THE PERIOD LOOKS TO BE THURSDAY NIGHT...AS THE SFC HIGH
APPROACHES. TEMPS SHOULD EASILY FALL INTO THE 40S...BUT IT IS
POSSIBLE THAT THESE TEMPS MAY BE TOO WARM...DEPENDING ON THE
EVENTUAL POSITION OF THE SFC HIGH.
BY EARLY NEXT WEEKEND MORE DISAGREEMENT EXISTS AMONG MODELS WITH THE
PATTERN EVOLUTION. HOWEVER...BOTH THE GFS/ECMWF DO BRING A SHORTWAVE
TROUGH INTO THE PLAINS ON SATURDAY...PERHAPS PROVIDING THE NEXT
OPPORTUNITY FOR SOME PRECIPITATION.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 1004 AM CDT SUN SEP 8 2013
ALL TAF SITES WILL BE IMPACTED BY PRECIP AT SOME POINT THE NEXT 24
HOURS. TIMING OF COURSE VERY DIFFICULT. SHOWER CLUSTER IN F-M AREA
MOVING EAST AND SPREADING NORTHEAST SOME SO WOULD EXPECT GFK-TVF TO
HAVE RAIN CHC INCREASE THRU 15Z. SOME SPOTTY MVFR CIGS IN THE WEST
THIS MORNING COULD EXPAND TO THE EAST...AND MAY HAVE TO ADD...AND
WILL MONITOR. BALANCE OF THE AFTN MORE DRY THAN WET....THEN HIT TSTM
CHANCES LATER TONIGHT ESP NRN VALLEY. ONCE STEADIER SHOWERS AND
STORMS DEVELOP OVERNIGHT...SHOULD BE MORE MVFR CONDITIONS AND EVEN
LOCALLY IFR NEAR STRONGER SHOWERS/STORMS...SO WILL CONTINUE TO
ADJUST AS WE HEAD THROUGH THIS EVENT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...ROGERS
SHORT TERM...RIDDLE
LONG TERM...MAKOWSKI/RIDDLE
AVIATION...DK
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
705 AM CDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 659 AM CDT SUN SEP 8 2013
VERY COMPLEX PRECIP PATTERN THIS MORNING. NO MODEL HANDLING IT
WELL SO GOING OFF CURRENT RADAR AND ADJUSTING FOR A FEW HOURS
AHEAD FOR IMMEDIATE UPDATES. MAIN MCS DWINDLED IN SE ND/NE SD AS
EXPECTED...BUT OUT AHEAD OF IT SOME CONVECTION FORMED IN THE FARGO
AREA PRODUCING UP TO 1 INCH OF RAIN QUICKLY. THIS CLUSGTER MOVING
EAST INTO DTL-FFM AREAS. DID UP POPS REST OF THIS MORNING INTO
WCNTRL MN FOR THIS. OTHERWISE MORE SCATTERED LIGHT ACTIVITY
NORTHWARD INTO THE NRN VALLEY. WOULD APPEAR THIS AFTN TO SEE
SCATTERED ACTIVITY BUT MOST OF THE FOCUS WILL WAIT TIL OVERNIGHT.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 324 AM CDT SUN SEP 8 2013
THREAT FOR HEAVY RAIN TONIGHT IS THERE...BUT WHERE AND HOW MUCH IS
THE MAIN QUESTION. MODEL QPF HAS BEEN RATHER POOR LATELY SO
CONFIDENCE IN AMOUNTS AND EXACT PLACEMENT POOR.
CURRENTLY...HAVE REMAINS OF TSTM COMPLEX THAT WAS IN SW/SCNTRL
ND/NRN SD MOVING EAST SLOWLY AND WEAKENING AS IT ENTERS THE
ABERDEEN-OAKES AREA. BUT HRRR DOES TAKE SOME SHOWERS EAST ACROSS
THE SD/ND BORDER REGION INTO WCNTRL THIS MORNING SO INCLUDED POPS
FOR THIS. HOWEVER IT IS RUNNING INTO QUITE A BIT OF DRY AIR SOON
AND SHOULD START TO REALLY WEAKEN.
MODELS 12Z SAT AND 00Z SUN INDICATED TSTM COMPLEX IN WCNTRL OR NW
ND AT THIS TIME AND INSTEAD DEVELOPMENT HAS BEEN FARTHER SOUTH IN
A NARROW 850 MB LOW LEVEL JET ZONE IN THE DICKINSON-HETTINGER-
BOWMAN AREA OF ND INTO NW SD. THUS PREV FCST IDEA OF LIKELY POPS
SPREADING INTO DVL BASIN THIS MORNING SEEMS A BIT OFF AND REDUCED
POPS TO HIGH CHANCE. RADAR HAS BEEN SHOWING SOME VERY LIGHT
SHOWERS FROM THE MID LEVEL CLOUD COVER MOVING INTO DVL BASIN BUT
WIDESPREAD RAINFALL NOT ANTICIPATED AS FOCUS WILL CONTINUE TO BE
MORE IN SW ND AND THEN INTO CNTRL ND TODAY WITH LOW LEVEL 850 MB
JET AND MOISTURE.
TONIGHT IS THE MAIN ACTION AS SHORT WAVE LIFTS NORTHEAST FROM
MONTANA TROUGH INTO WRN ND AND SFC LOW IS STILL FCST TO TRACK FROM
WRN SD INTO FAR NE SD/SE ND BY 12Z MON. ALL INDICATIONS STILL
FAVOR A LARGE TSTM COMPLEX NORTHWEST OF SFC LOW FROM SW-CNTRL INTO
NE ND/FAR NW MN/SRN MANITOBA OVERNIGHT INTO MONDAY MORNING. KEPT
IDEA OF HVY RAIN MENTIONED IN GRIDDS AND CATEGORICAL POPS MAINLY
NORTH OF A VALLEY CITY-FARGO-BEMIDJI AREAS. GFS IS QUITE STRONG
WITH LOW LEVEL JET (40 KTS) AND HAS MAX 850 INSTABLITY GRADIENT IN
SE-ECNTRL ND-WCNTRL MN 09Z-12Z MON PERIOD AND THUS IDEA OF
ELEVATED SVR VERY POSSIBLE ALONG SRN EDGE OF ANY MCS. FOR RAINFALL
PWATS OF 2 INCHES AT 12Z MON WOULD ARGUE FOR WIDESPREAD 1-2 INCH
RAIN POTENTIAL IN MCS AREA WITH LOCALLY HEAVIER AMOUNTS.
CONSIDERING PAST 60-90 DAYS HAVE BEEN VERY DRY IN OUR REGION RAIN
WILL SOAK INTO THE GROUND WITH RUNOFF MORE LIMITED TO CITY-URBAN
AREAS. AND WITH STILL UNCERTAINITY DUE TO POOR MODEL QPF
PERFORMANCES OF LATE AND THE FACT THAT MAIN RAIN IS TONIGHT HELD
OFF ON ANY FLASH FLOOD WATCHES. BUT SOME MAY BE NEEDED ONCE HVY
RAIN AREA CAN BE PEGGED BETTER.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 324 AM CDT SUN SEP 8 2013
500 MB UPPER TROUGH TO MOVE OVER MANITOBA/NE ND/NW MN MON NIGHT-
TUES AND THUS WILL LEAVE IN LOW POPS FOR THIS.
WEDNESDAY-SATURDAY...BROAD CANADIAN SFC HIGH PRESSURE WILL DROP FROM
CENTRAL CANADA INTO THE GREAT LAKES MID TO LATE WEEK WITH NORTHWEST
FLOW ALOFT...KEEPING THE AREA DRY. MORE SEASONABLE HIGH TEMPS IN
THE 60S TO LOW 70S ARE EXPECTED BY THURSDAY/FRIDAY. THE COOLEST
NIGHT DURING THE PERIOD LOOKS TO BE THURSDAY NIGHT...AS THE SFC HIGH
APPROACHES. TEMPS SHOULD EASILY FALL INTO THE 40S...BUT IT IS
POSSIBLE THAT THESE TEMPS MAY BE TOO WARM...DEPENDING ON THE
EVENTUAL POSITION OF THE SFC HIGH.
BY EARLY NEXT WEEKEND MORE DISAGREEMENT EXISTS AMONG MODELS WITH THE
PATTERN EVOLUTION. HOWEVER...BOTH THE GFS/ECMWF DO BRING A SHORTWAVE
TROUGH INTO THE PLAINS ON SATURDAY...PERHAPS PROVIDING THE NEXT
OPPORTUNITY FOR SOME PRECIPITATION.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 659 AM CDT SUN SEP 8 2013
ALL TAF SITES WILL BE IMPCATED BY PRECIP AT SOME POINT THE NEXT 24
HOURS. TIMING OF COURSE VERY DIFFICULT. SHOWER CLUSTER IN F-M AREA
MOVING EAST AND SPREADING NORTHEAST SOME SO WOULD EXPECT GFK-TVF
TO HAVE RAIN CHC INCREASE THRU 15Z. SOME SPOTTY MVFR CIGS ALSO
DEVELOPING IN SE ND AND THIS MAY IMPACT SOME SPOTS THIS MORNING.
BALANCE OF THE AFTN MORE DRY THAN WET....THEN HIT TSTM CHANCES
LATER TONIGHT ESP NRN VALLEY. MIX OF CIGS THIS AFTN-
TONIGHT...THINKING VFR CIGS MOST AREAS THIS AFTN WITH SOME MVFR
CIGS LIKELY IN RAIN AREAS OVERNIGHT. WINDS MAINLY EAST-SOUTHEAST 5
TO 15 KTS...OCNL GUST TO 20 KTS.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...RIDDLE
SHORT TERM...RIDDLE
LONG TERM...MAKOWSKI/RIDDLE
AVIATION...RIDDLE
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
635 AM CDT SUN SEP 8 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 409 AM CDT SUN SEP 8 2013
COMPLEX OF STORMS ACROSS NORTH CENTRAL SOUTH DAKOTA IS EXPECTED TO
SHIFT EAST THIS MORNING AND MAY SCRAPE THE NORTHERN EDGE OF THE
FORECAST AREA THIS MORNING. APPEARS AS THOUGH STORMS ARE DEVELOPING
BEHIND THE LEADING EDGE OF WARM AIR/THETA-E ADVECTION IN A MORE
UNSTABLE ENVIRONMENT. HI RES MODELS HANDLING THE SHORT TERM
RELATIVELY POORLY...WITH MOTH THE RAP AND THE HRRR SUGGESTING THE
ACTIVITY WOULD REMAIN WELL TO THE NORTH NEAR THE NORTH DAKOTA
BORDER. IN GENERAL...WIND SHEAR APPEARS TO BE FAIRLY WEAK SO AM NOT
ANTICIPATING SEVERE WEATHER THROUGH THE MORNING WITH THIS ACTIVITY
AS IT WORKS EAST.
INCREASING SOUTHERLY FLOW ACROSS THE AREA TODAY WILL LEAD TO ANOTHER
WARM AND HUMID DAY ACROSS THE REGION. HAVE TRIMMED BACK FORECAST
HIGHS IN THE NORTH WITH EXPECTED CONVECTION AND CLOUD COVER LIMITING
HEATING POTENTIAL SOME. WITH 925 HPA WINDS INCREASING TO NEAR 20
KNOTS...SHOULD SEE GUSTY WINDS OF 15-20 KNOTS.
EXPECT WIND GUSTS TO DROP OFF THROUGH THE EVENING...BUT SHOULD BE A
FAIRLY WARM NIGHT ACROSS THE REGION WITH SUSTAINED WINDS REMAINING
IN THE 10-15 KNOT RANGE. MODELS SUGGEST A SECONDARY WARM FRONT WILL
LIFT THROUGH THE REGION AND MAY BECOME THE FOCUSING MECHANISM FOR
ELEVATED STORMS ACROSS SOUTHWEST MINNESOTA AND ADJACENT AREAS. WENT
AHEAD AND INCREASED POPS FOR THIS AREA...WITH THE POTENTIAL FOR A
FEW STORMS TO BE MARGINALLY SEVERE WITH STRONGLY VEERING WIND SHEAR
PROFILES.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 409 AM CDT SUN SEP 8 2013
THE COLD FRONT WILL WORK ITS WAY ACROSS THE CWA MONDAY AFTERNOON
INTO THE OVERNIGHT HOURS. LOOKS LIKE GOOD HEATING POTENTIAL AHEAD OF
THE FRONT...WITH A SOUTHWESTERLY BREEZE GUSTING TO AROUND 30 MPH AND
COMPRESSIONAL HEATING. GIVEN OUR LACK OF GOOD MIXING RECENTLY...WAS
HESITANT TO GO TOO WARM WITH HIGHS...SO WHILE I DID GO HIGHER THAN
THE COOL BIAS CORRECTED VALUES...DID NOT GO WITH FULL MIXING TO 850
MB. FRONTAL TIMING IS STILL A BIT UNCERTAIN...AND THIS WILL HAVE AN
IMPACT ON HIGHS AS WELL. HIGHEST READINGS SHOULD BE ACROSS NORTHWEST
IOWA AND PORTIONS OF SOUTHWEST MINNESOTA...WHERE MID AND A FEW UPPER
90S SEEM PROBABLE. THE MARSHALL TO SIOUX FALLS TO YANKTON CORRIDOR
HAS THE HIGHER UNCERTAINTY...HOWEVER MOST MODEL SOLUTIONS KEEP THE
FRONT SLOW ENOUGH TO ALLOW THESE AREAS TO WARM INTO THE LOW TO MID
90S. CURRENTLY LOOKS LIKE HEAT INDICES WILL BE IN THE MID TO UPPER
90S...BUT SHOULD REMAIN BELOW 100...WITH THE INCREASED MIXING ALSO
HELPING TO LOWER DEWPOINTS SOME AHEAD OF THE FRONT.
LOOKING AT TWO POTENTIAL CHANCES FOR PRECIPITATION WITH THE FRONTAL
PASSAGE. THE PRE FRONTAL ATMOSPHERE SHOULD GENERALLY REMAIN CAPPED
THROUGH THE DAY. HOWEVER...RIGHT ALONG AND JUST BEHIND THE
FRONT...INDICATIONS THAT MOISTURE POOLING WILL RESULT IN AN INCREASE
IN DEWPOINTS. IT IS POSSIBLE THAT THIS...COMBINED WITH
FRONTOGENETICAL FORCING WILL BE ENOUGH TO BREAK THE CAP. IF THIS
HAPPENS IT WOULD LIKELY BE IN THE 21Z TO 03Z TIMEFRAME....GENERALLY
ALONG AND NORTHWEST OF A YANKTON TO WORTHINGTON LINE. THIS IMMEDIATE
POST FRONTAL ATMOSPHERE SHOULD BE CHARACTERIZED BY CAPE AROUND 1500
J/KG AND EFFECTIVE DEEP LAYER SHEAR OF ABOUT 30 KTS. SO WHILE
NOTHING TOO IMPRESSIVE...THESE PARAMETERS ARE ENOUGH TO SUGGEST AN
ISOLATED SEVERE STORM WOULD BE POSSIBLE. THE SECOND THREAT WILL BE
AS THE MAIN UPPER WAVE PASSES TO OUR NORTH. WHILE THE BEST PV
ADVECTION WILL REMAIN NORTH...A 60 TO 80 KT UPPER JET PASSING TO OUR
NORTH WILL PUT US IN FAVORED THE RIGHT ENTRANCE REGION. WHILE THIS
UPPER LEVEL SUPPORT APPEARS TOO LATE TO HELP WITH THE NEAR SURFACED
BASED CONVECTION POTENTIAL DISCUSSED ABOVE...IT MAY INTERACT WITH
THE 700 MB FRONT AND ALLOW FOR THE DEVELOPMENT OF ADDITIONAL SHOWER
AND THUNDERSTORMS FROM ABOUT 06Z ON. BY THIS TIME...MID LEVEL LAPSE
RATES BECOME PRETTY WEAK...AND THUS ELEVATED INSTABILITY WILL BE
LOW. MAYBE ENOUGH TO GET THUNDER...BUT WOULD NOT EXPECT ANYTHING
SEVERE WITH THIS ACTIVITY. WITH PWATS RUNNING 2 TO 3 STANDARD
DEVIATIONS ABOVE NORMAL...AND STORM MOTIONS NEARLY PARALLEL TO THE
MID LEVEL FRONT...LOCALLY HEAVY RAIN WOULD BE POSSIBLE. WILL JUST
KEEP HIGH CHANCE POPS FOR NOW...AS THE OVERNIGHT ACTIVITY WILL
PROBABLY BE PRETTY NARROW AND FOCUSED CLOSE TO THE 700 MB
FRONT...AND UNCERTAINTY EXISTS ON WHERE EXACTLY THIS WILL SET UP.
ALSO SOME MODEL RUNS ARE PRETTY WEAK ON QPF...POSSIBLY DUE TO THE
WEAK INSTABILITY AND A BIT OF A DRY LAYER AROUND 850 MB...SO WHILE
IT LOOKS LIKE A GOOD CHANCE MONDAY NIGHT...WILL CONTINUE TO HOLD OFF
ON LIKELY POPS FOR THE TIME BEING.
MODELS TRENDING TOWARDS STALLING THE FRONT FURTHER SOUTH THAN
PREVIOUSLY THOUGHT. THIS WILL PROBABLY LIMIT THE PRECIP POTENTIAL
TUESDAY INTO TUESDAY NIGHT...BUT WILL KEEP A SMALL POP GOING ACROSS
NORTHWEST IOWA. WE WILL SEE COOLER TEMPERATURES FILTER IN BEHIND THE
FRONT TUESDAY INTO WEDNESDAY AS THE RIDGE FLATTENS. ALTHOUGH STILL
EXPECTING ABOVE NORMAL READINGS IN THE LOW TO MID 80S. DEWPOINTS MAY
LINGER IN THE LOW 60S TUESDAY...BUT SHOULD FINALLY DROP INTO THE 50S
BY WEDNESDAY...BRINGING AN END TO THE HUMID PERIOD. A STRONG WAVE
MOVING ACROSS SOUTHERN CANADA WILL HELP PUSH A A BACKDOOR COLD FRONT
AND EVEN COOLER AND LESS HUMID CONDITIONS INTO THE REGION THURSDAY
INTO FRIDAY. EXPECTING HIGHS IN THE 70S BOTH DAYS...WITH ONLY AREAS
NEAR THE MISSOURI RIVER POTENTIALLY HITTING 80. ALSO WOULD EXPECT
COOLER NIGHTTIME TEMPERATURES WITH HIGH PRESSURE CENTERED TO OUR
NORTHEAST. FRIDAY MORNING CURRENTLY LOOKS TO BE THE
COOLEST...POSSIBLY BEING THE FIRST NIGHT IN A WHILE WHERE LOWS
ACTUALLY END UP BELOW NORMAL...IN THE UPPER 40S TO MID 50S. AS THE
RIDGE BEGINS TO BUILD BACK IN LATER FRIDAY INTO SATURDAY...THE
THUNDERSTORM THREAT SHOULD AGAIN BEGIN TO INCREASE OVER THE REGION.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 628 AM CDT SUN SEP 8 2013
SEVERAL AVIATION ISSUES THIS MORNING. ELEVATED SHOWERS MOVING INTO
THE HURON AREA SHOULD NOT RESULT IN A REDUCTION IN CONDITIONS
BELOW VFR. SHOWERS SHOULD REMAIN NORTH OF THE KFSD TERMINAL.
FURTHER TO THE SOUTH...LOW LYING FOG NEAR THE KSUX TERMINAL IS
EXPECTED TO BURN OFF A FEW HOURS AFTER SUNRISE. SOUTHERLY WINDS
WILL INCREASE THROUGHOUT THE DAY AND BECOME SOMEWHAT GUSTY. THE
LOW LEVEL JET IS EXPECTED TO INCREASE TO 40-50 KNOTS ACROSS THE
FORECAST AREA TONIGHT...AND HAVE ADDED LOW LEVEL WIND SHEAR TO
BOTH KHON AND KFSD TERMINALS. CONSIDERED ALSO ADDING IT TO
KSUX...THOUGH WINDS APPEARED TO BE SOMEWHAT MARGINAL THERE SO
OPTED TO LEAVE OUT FOR NOW.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...CHENARD
AVIATION...
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
942 AM CDT SUN SEP 8 2013
.DISCUSSION...
NO CHANGES TO THE MORNING FORECAST ARE ANTICIPATED.
HAVE BEEN MONITORING MCS NEAR ST. LOUIS...WHICH IS SLOWLY
WEAKENING. THE LATEST HRRR AND 12Z NAM MODEL IS ALSO INDICATING
THIS TREND THROUGH THE EARLY AFTERNOON HOURS...WITH SOME ISOLATED
REDEVELOPMENT ON IT`S SOUTHERN FLANK LATER TODAY ACROSS OUR NORTH.
THUS LATE AFTERNOON AND OVERNIGHT RAIN CHANCES LOOK TO BE ON
TRACK FOR NOW. QUESTION THAT ARISES FOR THE AFTERNOON FORECAST
PACKAGE WILL BE COVERAGE AFTER SUNSET AS THE NAM KEEPS ACTIVITY
GOING THROUGH LATE MONDAY MORNING. IF THIS SCENARIO
UNFOLDS...SEVERAL LOCATIONS ALONG AND NORTH OF INTERSTATE FORTY
COULD RECEIVE A WELCOMED SIGNIFICANT RAINFALL.
HIGH LEVEL MOISTURE FROM COMPLEX WILL CONTINUE TO BUILD SOUTH
INTO OUR AREA OVER THE NEXT 3 TO 6 HOURS...KEEPING HIGHS A FEW
DEGREES BELOW GUIDANCE.
JAB
&&
.PREV DISCUSSION... /ISSUED 630 AM CDT SUN SEP 8 2013/
DISCUSSION... /ISSUED 507 AM CDT SUN SEP 8 2013/
FEW CHANGES TO RECENT FORECASTS. A LARGE AN UNSEASONABLY STRONG
UPPER LEVEL HIGH PRESSURE RIDGE REMAINS THE PRIMARY WEATHER
FEATURE...WHICH WILL RESULT IN DAYTIME TEMPS AVERAGING SEVERAL
CATEGORIES ABOVE EARLY/MID SEPTEMBER CLIMATOLOGICAL NORMALS.
THE UPPER RIDGE WAS CENTERED OVER THE CENTRAL PLAINS EARLY THIS
MORNING...WITH WEAK NORTH/NORTHWEST UPPER LEVEL FLOW OVER THE
MIDSOUTH. GOES WATER VAPOR IMAGERY SHOWED A WEAK SHORTWAVE
EMBEDDED IN THIS NORTHWEST FLOW OVER CENTRAL IL. THIS FEATURE WILL
DROP INTO THE MIDSOUTH BY THIS EVENING... SLOWING ITS PROGRESS
WITH THE APPROACH OF THE UPPER RIDGE CENTER. A FEW THUNDERSTORMS
MAY OCCUR TO THE NORTH AND NORTHEAST OF MEMPHIS THIS AFTERNOON AND
EARLY EVENING...WHERE COOLER MIDLEVEL TEMPS AID IN WEAKENING THE
OTHERWISE ROBUST CINH /CONVECTIVE INHIBITION/.
THE GFS AND NAM DIFFER GREATLY WITH DAYTIME RAIN CHANCES MONDAY
AND TUESDAY. THE NAM CONTINUES TO DEVELOP RATHER ROBUST QPF FIELDS
UNDER THE UPPER RIDGE CENTER...WHILE THE GFS SHOWS MUCH MORE LIMITED
QPF. SOUNDINGS ARE SIMILAR ENOUGH BETWEEN THE TWO MODELS AND
SUSPECT THE DIFFERENCES ARE PRIMARILY DUE TO CONVECTIVE PARAMETRIZATION
IN THE WEAK KINEMATIC ENVIRONMENT UNDER THE ROBUST UPPER RIDGE.
THE DRIER GFS APPEARS TO BE WELL CORROBORATED BY THE ECMWF AND AS
SUCH HAS BEEN USED AS THE BASIS FOR FORECAST POPS.
MIDWEEK PERIODS LOOK TO BE HOT UNDER THE UPPER RIDGE. A DEEP BUT
PROGRESSIVE UPPER TROF WILL DROP INTO THE NORTHEASTERN THIRD OF THE
U.S. ON THURSDAY...BRINGING UPPER LEVEL NORTHWEST FLOW AND ASSOCIATED
SURFACE COLD FRONTAL PASSAGE TO THE MIDSOUTH. THIS FRONT WILL PROVIDE
FOCUS FOR ISOLATED THUNDERSTORM DEVELOPMENT...FOLLOWED BY NOTICEABLY
LOWER DEWPOINTS A SOME RELIEF FROM THE HEAT HEADED INTO THE EARLY
WEEKEND.
THE UPPER LEVEL RIDGE WILL QUICKLY BUILD BACK BY SUNDAY...CENTERED
OVER THE OZARK PLATEAU. THIS RIDGE WILL THEN EXPAND EASTWARD
THROUGH THE MIDDLE OF NEXT WEEK... DOMINATING THE SOUTHEASTERN
THIRD OF THE LOWER 48 BEYOND THE MID SEPTEMBER MARK.
PWB
&&
.AVIATION...
12Z TAF SET
VFR CONDITIONS EXPECTED OVER NEXT 24 HOURS. CLUSTER OF SHRAS/TSRAS
CURRENTLY NORTH OF ST LOUIS WILL PUSH SOUTH TODAY. EXPECT A DYING
BROKEN LINE OF SHRAS TO MOVE ACROSS MO/AR AND KY/TN BORDER AROUND
20Z. WILL MENTION OF VCSH AT KJBR AND KMKL. SHRAS SHOULD DISSIPATE
BY 00Z. REDEVELOPMENT OF SHRAS/TSRAS COULD OCCUR DURING EVENING
INTO OVERNIGHT HOURS AS A SHORTWAVE MOVES TO THE AREA. NOT
CONFIDENT ENOUGH TO MENTION IN TAFS AT THIS POINT. LIGHT SW WINDS
EXPECTED THROUGH THE PERIOD.
KRM
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 94 75 95 74 / 10 10 20 10
MKL 92 67 93 68 / 20 20 10 10
JBR 96 70 96 69 / 20 20 20 10
TUP 94 70 94 69 / 0 10 20 10
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
230 PM PDT SUN SEP 8 2013
.SYNOPSIS...
A SLIGHT COOLING TREND WILL OCCUR THROUGH MONDAY...BUT TEMPERATURES
WILL STILL BE ABOVE NORMAL. MORE SIGNIFICANT COOLING IS LIKELY
TUESDAY AND WEDNESDAY WITH TEMPERATURES DOWN TO NEAR OR SLIGHTLY
BELOW NORMAL LEVELS...THEN ANOTHER WARMING TREND IS EXPECTED FOR
LATE IN THE WEEK. THERE WILL BE A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE EASTERN MOUNTAINS AND THE ANTELOPE VALLEY
DURING THE AFTERNOON AND EVENING HOURS THROUGH WEDNESDAY.
&&
.SHORT TERM (TODAY-WED)...LONG WAVE RIDGE OVER THE WEST COAST AND
CENTERED OVER THE CENTRAL PORTION OF SOUTHERN OREGON AND ONE UPPER
LEVEL CYCLONIC CIRCULATION CENTERED OVER SOUTHERN CALIFORNIA AND A
SECOND AND THIRD OVER THE PACIFIC NORTHWEST WAS INITIALIZED
REASONABLY WELL THIS MORNING. THE LONG WAVE RIDGE WILL PERSIST
THROUGH THE PERIOD WHILE THE CYCLONIC CIRCULATIONS SHIFT EAST AND
SOUTH OVER THE AREA. HAVE INCLUDED A SLIGHT CHANCE OF THUNDERSTORMS
IN THE VICINITY OF VENTURA/KERN COUNTY LINE THIS EVENING. AND WILL
CONTINUE WITH A SLIGHT CHANCE OF THUNDERSTORMS OVER THE DESERT AND
MOUNTAINS IN LA COUNTY. PICTURES FROM SPACE VERIFIED GUIDANCE WHERE
MID LEVEL MOISTURE WAS CONSOLIDATING OVER THE NORTHERN PORTION OF
VENTURA COUNTY AT THIS TIME. RUC SOUNDING IN THE VICINITY OF THE
COUNTY LINE INDICATED A WEAKENING MID LEVEL CAP THROUGH THE
AFTERNOON AND SOUNDING WILL BECOME MODERATELY UNSTABLE. MOISTURE WAS
LIMITED EAST OF THE AREA TODAY AND EXPECT LITTLE PRECIPITATION.
THUNDERSTORMS AND
SHOWERS ARE EXPECTED TO MOVE WEST SOUTHWEST AROUND 10 KT IN VENTURA
COUNTY. RUC CONTINUES TO INDICATE A RELATIVELY STABLE SOUNDING OVER
SAN GABRIEL MOUNTAINS AND IF THUNDERSTORMS DEVELOP THEY WILL MOVE
WEST AS WELL. OTHERWISE CURRENT TEMPERATURES WERE 5 TO 10 DEGREES
COOLER THAN SATURDAY AT THIS TIME. A SLIGHTLY DEEPER MARINE LAYER IS
EXPECTED AND INFLUENCE TEMPERATURES PRODUCING A MIXED TREND MONDAY.
TEMPERATURES WILL DIFFER SLIGHTLY FROM TODAY AND WARM ALONG THE
CENTRAL COAST AND COOL SOUTH OF POINT CONCEPTION. INLAND
TEMPERATURES WILL LIKELY CONTINUE 3 TO 10 DEGREES ABOVE NORMAL. A
COOLING TREND BY 3 TO 6 DEGREES OVER THE ENTIRE AREA IS EXPECTED
TUESDAY...AN ONSHORE PRESSURE GRADIENT WILL STRENGTHEN AS A SURFACE
RIDGE BUILDS OVER THE BIGHT AND MARINE AIR WILL SHIFT INLAND. A
MIXED TEMPERATURE TREND IS EXPECTED WEDNESDAY AND TEMPERATURES WILL
WARM A COUPLE OF DEGREES OVER THE SOUTH HALF AND CONTINUE TO COOL A
COUPLE DEGREES OVER THE NORTH HALF. WILL CONTINUE WITH LOW POPS WITH
THUNDERSTORMS OVER THE MOUNTAINS EACH AFTERNOON THROUGH WEDNESDAY
WITHIN A RELATIVELY DRY AIR MASS.
.LONG TERM (THU-SUN)...THE LONG WAVE RIDGE IS EXPECTED TO WEAKEN AND
SHIFT EAST THROUGH THE PERIOD AND A BROAD LONG WAVE TROUGH WILL
DEVELOP UPSTREAM. WILL CONTINUE DRY THROUGH THE PERIOD. AS THE LONG
WAVE TROUGH OVER THE WESTERN PACIFIC TODAY SHIFTS EAST THROUGH THE
PERIOD A SURFACE FRONT IS EXPECTED TO MOVE OVER THE EASTERN PACIFIC
FRIDAY AND MOVE OVER NORTHERN CALIFORNIA SATURDAY. THE SOUTHERN
PORTION OF THE FRONT WILL LIKELY DISSIPATE NORTHWEST OF THE AREA
SATURDAY. LITTLE CHANGE IS EXPECTED WITH TEMPERATURES ON THURSDAY
THEN AS THE THE SURFACE FRONT OVER THE EASTERN PACIFIC APPROACHES
TEMPERATURES ARE EXPECTED TO WARM A FEW DEGREES OVER THE ENTIRE AREA
FRIDAY AND INLAND AREAS WILL LIKELY BE 5 TO 10 DEGREES ABOVE NORMAL.
A SLIGHT COOLING TREND IS THEN EXPECTED SATURDAY THROUGH SUNDAY
THOUGH TEMPERATURES WILL LIKELY CONTINUE 4 TO 8 DEGREES ABOVE
SEASONAL NORMAL.
&&
.AVIATION...08/1735Z...
OVERALL...MODERATE CONFIDENCE IN THE 18Z TAF PACKAGE. LATEST
SATELLITE SHOWS STRATUS DISSIPATING ACROSS COASTAL TAF SITES...WITH
CLEAR SKIES ACROSS INLAND TAF SITES. THROUGH THE EARLY
EVENING...WILL EXPECT VFR CONDS TO PREVAIL. OVERNIGHT...EXPECT
IFR/LIFR CONDS TO DEVELOP ACROSS COASTAL TAF SITES...WITH
LOW/MODERATE CONFIDENCE IN TIMING OF STRATUS RETURN.
KLAX...MODERATE CONFIDENCE IN 18Z TAF. THERE IS A 30% CHANCE OF IFR
CONDS BETWEEN 19Z AND 01Z. OVERNIGHT...CONFIDENCE HIGH IN RETURN OF
STRATUS...ALTHOUGH LOW CONFIDENCE IN TIMING OF RETURN.
KBUR...HIGH CONFIDENCE IN 18Z TAF.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).
&&
$$
PUBLIC...30
AVIATION...KITTELL
SYNOPSIS...SWEET
WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
332 PM CDT SUN SEP 8 2013
.SYNOPSIS...
ISSUED AT 330 PM CDT SUN SEP 8 2013
A STATIONARY FRONT WAS DRAPED ACROSS THE FAR SOUTHERN CWA EARLY THIS
AFTERNOON. WIDESPREAD STRATUS NORTH OF THE FRONT HAS BEEN SLOWLY
ERODING AND LIFTING NORTH... WITH THE MOST EXTENSIVE STRATUS NEAR
AND NORTH OF HWY 20 WHILE ELSEWHERE THE STRATUS HAS EVOLVED INTO
SCT-BKN STRATOCU DECK. WHERE THE STRATUS HAS BEEN SOLID AND LINGERED
ALL DAY NORTH OF HWY 30 TEMPS HAVE BEEN HELD DOWN INTO THE 70S IN
MANY AREAS... WHILE TO THE SOUTH WITH SOME SOLAR INSOLATION TEMPS
HAVE WARMED INTO THE 80S WITH A FEW SITES IN THE UPPER 80S OVER THE
FAR SOUTHERN CWA. MOISTURE WAS POOLING NEAR THE BOUNDARY WITH DEWPTS
IN THE UPPER 60S AND LOWER 70S MAKING FOR RATHER HUMID CONDITIONS
THOUGH BEING OFFSET AT TIMES BY GUSTY EASTERLY WINDS. THE PATTERN
ALOFT FEATURES LARGE HEAT DOME CENTERED OVER KANSAS... WITH NORTHWEST
FLOW OVER OUR AREA. AN UPPER LEVEL DISTURBANCE WHICH BROUGHT
AREAS OF SIGNIFICANT RAINFALL OF 2-4+ INCHES TO PORTIONS OF WEST
CENTRAL ILLINOIS LATE LAST NIGHT WAS PASSING SOUTH NEAR THE ST LOUIS
METRO ATTM. ANOTHER DISTURBANCE WAS SEEN TOPPING THE UPPER LEVEL RIDGE
AND SLIDING E/SE FROM DAKOTAS THROUGH MINNESOTA.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 330 PM CDT SUN SEP 8 2013
HEAT AND HUMIDITY AND NEED FOR HEADLINES MONDAY IS THE MAIN CONCERN.
STATIONARY FRONT TO LIFT BACK NORTH AS WARM FRONT OVERNIGHT THROUGH
MONDAY MORNING. RAIN CHANCES ARE NOT ZERO TONIGHT BUT LACK OF
COHERENT TRIGGER WITH ONLY WEAK WARM ADVECTION/ISENTROPIC LIFT WOULD
SUGGEST ANY ACTIVITY FAR TOO SPARSE IN COVERAGE TO WARRANT ANY MENTION.
EXPECT TO SEE CONTINUED DECREASE IN STRATUS THROUGH SUNSET THEN WITH
MOISTURE POOLING WOULD ANTICIPATE ADDITIONAL LOW CLOUD AND SOME FOG
DEVELOPMENT OVERNIGHT INTO EARLY MONDAY MORNING AHEAD OF THE WARM
FRONT. THINKING ANY FOG MOSTLY AVIATION CONCERN BUT CANT RULE OUT SOME
DENSE FOG GIVEN THE ABUNDANT LOW LEVEL MOISTURE AND WILL NEED TO BE
MONITORED. STAYED WITH BLEND OR WARM SIDE FOR LOWS WITH RANGE FROM THE
MID 60S TO SOME LOWER 70S. WARM FRONT TO LIFT NORTH OF THE CWA BY MONDAY
AFTERNOON. THIS WILL SET THE STAGE FOR VERY WARM TO HOT AFTERNOON WITH
MODELS SHOWING 850 MB TEMPS CLIMBING TO AROUND 22-24C. MIXING TO THE
SURFACE YIELDS MAX TEMPS OF ROUGHLY 92-98F WITH WARMEST READINGS ACROSS
THE SOUTHWEST 1/3-2/3 OF CWA. DEWPTS WILL START OUT IN THE UPPER 60S
TO LOWER 70S BUT WITH MIXING AND DRYING FROM ALOFT ANTICIPATE LOWERING
INTO THE LOWER TO MIDDLE 60S DURING PEAK HEATING. THIS WOULD PUT HEAT
INDICES IN THE RANGE OF AROUND 94-99F OR MAINLY JUST BELOW ADVISORY
CRITERIA. HAVE HELD OFF THEN ON HEAT ADVISORY AND WILL CONTINUE TO
HIGHLIGHT IN HWO AND WX STORY. SOME FIRE WX CONCERNS BUT FUELS NOT THERE
YET FOR HEADLINES. BUT... GIVEN HOW DRY IT HAS BEEN AND POTENTIAL
OF SOME GUSTY WINDS IN THE AFTERNOON IT COULD BE DIFFICULT CONTROLLING
ANY FIRES IN THE RIGHT FUELS WITH DITCHES BEING OF MOST CONCERN AND
PLAN TO MENTION IN HAZARDOUS WEATHER OUTLOOK.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 PM CDT SUN SEP 8 2013
BREAKDOWN OF THE UPPER LEVEL HIGH AND CHANGE TO A NW FLOW ALOFT WILL
RESULT IN COOLER...AND POSSIBLY EVEN BELOW NORMAL TEMPERATURES FOR
LATE WEEK INTO NEXT WEEKEND. CONDITIONS TO REMAIN DRY OUTSIDE OF
THUNDERSTORMS CHANCES WITH THE COLD FRONTAL PASSAGE THAT MARKS THIS
TRANSITION TUESDAY NIGHT INTO WED...AND ANOTHER COLD FRONT ON
SUNDAY.
MONDAY NIGHT AND TUESDAY...VERY WARM AIRMASS WILL BE IN PLACE AHEAD
OF THE LEAD COLD FRONT THAT BEGINS TO DROP SOUTH THROUGH THE AREA
TUESDAY AFTERNOON. LIGHT SOUTHWEST WINDS...PREFRONTAL COMPRESSIONAL
WARMING...AND LOW LEVEL MOISTURE CONVERGENCE SHOULD HOLD MINS IN THE
UPPER 60S AND LOWER 70S. TUESDAY...MODEL CONSENSUS HAS THE FRONT
DROPPING TO ROUGHLY THE HIGHWAY 30 CORRIDOR BY LATE AFTERNOON.
ANOTHER DAY OF DEEP MIXING INTO VERY WARM AIR ALOFT AHEAD OF THE
FRONT SHOULD PUSH HIGHS BACK INTO THE LOWER TO MID 90S SOUTH. IN THE
NORTH...WILL HAVE A SLIGHT CHANCE OF POST FRONTAL AFTERNOON
THUNDERSTORMS. BEFORE THE WEAK FRONTAL PASSAGE...TEMPERATURES SHOULD
REACH THE UPPER 80S TO LOWER 90S. LOW LEVEL MOISTURE POOLING WILL
HOLD DEWPOINTS IN THE LOWER TO MID 60S. THIS COMBINATION WILL RESULT
IN HEAT INDEX READINGS AS HIGH AS THE MID TO UPPER 90S IN THE
SOUTH...JUST BELOW ADVISORY CRITERIA.
WILL CONTINUE CHANCE POPS FOR SHOWERS AND THUNDERSTORMS AS THE
INITIAL COOL FRONT SLOWLY SAGS SOUTH THROUGH THE AREA. ADDITIONAL
WEAK FORCING WILL BE PROVIDED BY THE RIGHT ENTRANCE REGION TO AN
UPPER LEVEL JET MOVING THROUGH THE UPPER GREAT LAKES AND ONTARIO TUE
NIGHT...THEN AN UPPER LEVEL TROUGH DIGGING INTO SOUTHERN ONTARIO
WEDNESDAY. CLOUD COVER AND LINGERING RH WILL LIMIT LOWS TO THE MID
60S NORTH TO LOWER 70S SOUTH TUE NIGHT...WITH HIGHS THEN IN THE 80S
AT BEST WEDNESDAY.
NW FLOW THAT FOLLOWS AS THE UPPER LEVEL TROUGH DEVELOPS OVER EASTERN
CANADA WILL ALLOW COOLER AIR AT 850 MB AND SURFACE HIGH PRESSURE TO
DROP SOUTH INTO THE UPPER MS VALLEY AND GREAT LAKES THU AND FRI.
MODEL CONSENSUS HAS HIGHS LIMITED TO THE LOWER TO MID 80S THU...THEN
MAINLY 70S FRI INTO THE WEEKEND WHILE LOWS WILL BE MAINLY IN THE
50S. MINS IN THE 40S WILL BE POSSIBLE OVER ESPECIALLY THE NORTHEAST
FRIDAY NIGHT WHEN THE HIGH PRESSURE CENTER MAKES ITS CLOSEST PASS
OVER LOWER MI. THU THROUGH SATURDAY WILL BE ANOTHER DRY PERIOD...
FOLLOWED BY RAIN CHANCES ON SUNDAY...WHERE THE LATEST GFS AND ECMWF
HAVE COLD FRONTAL PASSAGE THAT WILL HAVE AN AXIS OF GULF MOISTURE
RETURN FLOW TO WORK WITH.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1240 PM CDT SUN SEP 8 2013
NEARLY STATIONARY FRONTAL ZONE IS DRAPED OVER FAR SOUTHEAST IOWA AND
WEST CENTRAL ILLINOIS. FAIRLY WIDESPREAD STRATUS WITH MVFR CIGS WAS
NOTED NORTH OF THE FRONT IMPACTING ALL TERMINALS. ANTICIPATE THE
STRATUS AND MVFR CIGS TO LIFT TO VFR AND SCATTERING AT THE TERMINALS
FROM SOUTH TO NORTH THROUGH 00Z. STATIONARY FRONT IS EXPECTED TO
LIFT BACK NORTH AS A WARM FRONT THROUGH THE TERMINALS LATE TONIGHT
AND MONDAY MORNING. ANTICIPATE MORE LOW CLOUDS AND FOG WITH IFR TO
MVFR CONDITIONS DEVELOPING NORTH OF THE WARM FRONT AS SUGGESTED BY
MOST GUIDANCE INCLUDING HRRR...SREF AND RAP MODEL VSBY/CIG PLOTS.
CONDITIONS TO RETURN TO VFR AT ALL SITES BY 18Z MONDAY AS WARM FRONT
LIFTS NORTH OF THE TERMINALS. WINDS WILL BE EASTERLY AT 5-10 KTS
THIS AFTERNOON AND EVENING... WITH OCCASIONAL GUSTS NEAR 20 KTS POSSIBLE
THIS AFTERNOON. LATE TONIGHT AND MONDAY MORNING AS THE WARM FRONT PASSES
WINDS WILL BECOME SOUTHERLY AROUND 10 KTS WITH SOME GUSTS POSSIBLE LATE
MORNING. RAIN CHANCES ARE NOT ZERO DURING THE PERIOD... BUT APPEAR TOO
SMALL FOR INCLUSION IN TERMINALS.
&&
.CLIMATE...
ISSUED AT 235 PM CDT SUN SEP 8 2013
RECORD HIGHS FOR SEPTEMBER 9...
MOLINE.........99 IN 1933
CEDAR RAPIDS...98 IN 1955
DUBUQUE........97 IN 1955
BURLINGTON.....100 IN 1912
RECORD HIGHS FOR SEPTEMBER 10...
MOLINE.........95 IN 1983
CEDAR RAPIDS...98 IN 1931
DUBUQUE........97 IN 1895
BURLINGTON.....97 IN 1933
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...05
SHORT TERM...05
LONG TERM...SHEETS
AVIATION...05
CLIMATE...05
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1259 PM CDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 723 AM CDT SUN SEP 8 2013
THE CONVECTION HAS EXITED THE AREA AND A PERIOD OF QUIET WX IS
EXPECTED THROUGH THE EARLY AFTERNOON. PER THE RAP/WRF TRENDS THE
LOW CLOUDS COMING OFF LAKE MICHIGAN ARE MOVING JUST A BIT FASTER
THAN EXPECTED. HOWEVER...WITH THE SUN NOW UP THE SOUTHWARD
EXPANSION OF THE CLOUDS SHOULD BE HALTED. CLOUD COVER WILL MAKE
TEMPERATURES INTERESTING TODAY. THOSE AREAS THAT HAVE CLOUDS
SHOULD REMAIN IN THE UPPER 60S TO LOWER 70S FOR A GOOD PORTION OF
THE MORNING BEFORE RISING.
CONVECTION THIS AFTERNOON IS QUESTIONABLE. THERE IS A WARM LAYER
ALOFT THAT MAY PREVENT ANY CONVECTION FROM OCCURRING. IF
CONVECTION DOES OCCUR THE MOST LIKELY AREA WILL BE SOUTH OF I-80
WHERE THE STRONGER DIFFERENTIAL HEATING WILL OCCUR.
&&
.SYNOPSIS...
ISSUED AT 315 AM CDT SUN SEP 8 2013
06Z SFC ANALYSIS HAS A WEAK LOW NORTHEAST OF KOTM WITH A FRONT
PASSING NORTH OF THE QUAD CITIES AND EAST INTO NORTHERN INDIANA. A
COLD FRONT RAN FROM THE LOW SOUTHWEST TO THE NE/KS LINE. AN
INVERTED TROF RAN FROM THE LOW INTO SOUTHEAST MINNESOTA WHILE
ANOTHER TROF RAN SOUTHEAST FROM THE LOW INTO CENTRAL ILLINOIS. DEW
POINTS WERE IN THE 60S ACROSS THE MIDWEST WITH POCKETS OF 70
AROUND THE LOW AND COLD FRONT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT SUN SEP 8 2013
THE CONCERNS ARE THE CONVECTION IN THE SOUTHERN CWFA AND THE
APPROACHING LOW CLOUDS FROM WISCONSIN.
THE CONVECTION AROUND KGBG AND NOW IMMEDIATELY WEST OF THERE IS
CONTINUOUSLY FORMING AND MOVING OVER THE SAME AREAS. THE CULPRIT
IS A COMBINATION OF CONVERGENCE AROUND THE TROF OVER THAT AREA.
PER THE RAP TRENDS THIS IS EXPECTED TO CONTINUE FOR THE NEXT
SEVERAL HOURS BEFORE WEAKENING. THUS SOME ISOLATED AREAS WILL SEE
LOCALLY HEAVY RAINFALL THROUGH SUNRISE.
THE RAP IS DOING A RESPECTABLE JOB OF DEPICTING THE LOW CLOUDS
APPROACHING FROM WISCONSIN AND WILL ENTER THE NORTHERN CWFA PRIOR
TO SUNRISE.
FOR TODAY...THE CONVECTION IN THE SOUTHERN CWFA SHOULD DISSIPATE
AFTER SUNRISE WHILE LOW CLOUDS CONTINUE TO OVERSPREAD ACROSS THE
NORTHEAST THIRD TO 40 PERCENT OF THE CWFA. THE FRONT WILL SLOWLY
SAG SOUTH AND IS EXPECTED TO CLEAR THE CWFA DURING THE AFTERNOON.
DIURNAL HEATING IS EXPECTED TO ALLOW VERY ISOLATED SHOWERS AND
THUNDERSTORMS TO DEVELOP DURING THE AFTERNOON IN THE SOUTHERN CWFA
WHERE CONVECTIVE TEMPERATURES SHOULD BE ACHIEVED IN SPITE OF THE
WARM AIR ALOFT.
TONIGHT...MAINLY QUIET AND DRY CONDITIONS ARE EXPECTED AS THE FRONT
BEGINS MOVING BACK NORTH AS A WARM FRONT. ..08..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 315 AM CDT SUN SEP 8 2013
TEMPERATURES WILL BE THE MAIN CONCERN MONDAY AND TUESDAY AS VERY
WARM AIR SURGES NORTHEAST BEHIND A WARM FRONT MOVING THROUGH THE
FORECAST AREA BY EARLY MONDAY AFTERNOON. H8 TEMPS ARE FORECAST TO
INCREASE INTO THE LOW TO MID 20/S IN THE WARM SECTOR BY MONDAY
AFTERNOON. MIXING THESE TEMPERATURES TO THE SURFACE YIELDS MAX
TEMPS IN THE MID TO UPPER 90S WHICH LOOKS REASONABLE FOR THE
SOUTHWEST 2/3RDS. WITH THE WARM FRONT MOVING OUT OF THE NORTHEAST
COUNTIES DURING THE AFTERNOON...HIGHS WERE KEPT IN THE LOW 90S.
DEWPOINTS SHOULD BE IN THE MID OR UPPER 60S MONDAY WHICH WILL BE
HIGH ENOUGH TO PRODUCE HEAT INDEX VALUES AROUND 100 DURING THE
AFTERNOON. BY TUESDAY A COLD FRONT WILL BE JUST NORTHWEST OF THE
AREA AT 12Z AND WILL MOVE SLOWLY SOUTH REACHING THE SOUTHEASTERN
COUNTIES BY LATE AFTERNOON. AREAS ALONG AND SOUTH OF HIGHWAY 30
WILL HAVE PLENTY OF TIME TO HEAT UP AND SHOULD SEE ANOTHER DAY OF
MID 90 TEMPERATURES. TO THE NORTH WITH THE FRONT MOVING THROUGH
EARLY IN THE DAY...HIGHS SHOULD BE AROUND 90. SOUTHWEST WINDS AHEAD
OF THE FRONT ARE PROGGED TO TAP DRIER AIR OVER THE
PLAINS...KEEPING DEWPOINTS LOWER THAN THOSE EXPECTED ON MONDAY.
THE DRIER AIR WILL KEEP HEAT INDEX VALUES UNDER 100. HIGHS IN THE
90S MONDAY AND TUESDAY WILL BE CLOSE TO RECORD HIGHS FOR THE 9TH
AND 10TH OF SEPTEMBER. MONDAYS RECORDS ARE AROUND 100 AND SHOULD
BE JUST OUT OF REACH BUT SLIGHTLY COOLER RECORDS FOR TUESDAY WILL
BE ATTAINABLE ESPECIALLY AT MOLINE AND BURLINGTON. SEE THE CLIMATE
SECTION BELOW FOR MONDAY/S AND TUESDAY/S RECORD HIGHS AND DATE OF
THE LAST OCCURRENCE.
THE RAIN THREAT WILL BE NIL THROUGH EARLY TUESDAY AFTERNOON. THEN
JUST A SLIGHT CHANCE NORTH PRIOR TO 00Z WEDNESDAY. THE WARM SECTOR
SHOULD BE CAPPED...AND AS STATED ABOVE DEWPOINTS WILL BE DRYING
OUT SOME AHEAD OF THE FRONT. THE BEST POTENTIAL FOR RAIN WILL BE
POST FRONTAL WHERE LOW LEVEL MOISTURE WILL BE POOLING AND THE MID
LEVEL CAP STARTS TO ERODE. MODELS WERE ALSO SHOWING SOME DEEP
LAYER FGEN IN THE ENTRANCE REGION OF A H3 80KT JET STREAK OVER MN
AND WI WHICH SHOULD CONTRIBUTE TO THE POST FRONTAL FORCING.
DESPITE THESE SIGNALS FAVORING RAIN...THERE IS STILL A WIDE RANGE
OF QPF FORECASTS AMONG THE MODELS WITH THE LATEST ECM RUN DRY FOR
NEARLY ALL OF THE CWFA. WITH THE MODELS STILL LENDING A LOT OF
UNCERTAINTY TO THE PRECIP FORECAST FOR TUESDAY NIGHT AND WEDNESDAY...
HAVE KEPT THE POPS IN THE CHANCE CATEGORY.
THE FRONT WILL BE SOUTH OF THE AREA BY TUESDAY EVENING ENDING ANY
RAIN THREAT FOR THE REST OF THE WEEK. HIGH PRESSURE SLIDING
SOUTHEAST THROUGH THE GREAT LAKES BY LATE WEEK WILL BRING COOL DRY
AIR TO THE REGION. BY FRIDAY AND SATURDAY WE SHOULD SEE HIGHS IN
THE 70S OVER THE ENTIRE AREA WITH LOWS IN THE 40S AND 50S BY
SATURDAY MORNING.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1240 PM CDT SUN SEP 8 2013
NEARLY STATIONARY FRONTAL ZONE IS DRAPED OVER FAR SOUTHEAST IOWA AND
WEST CENTRAL ILLINOIS. FAIRLY WIDESPREAD STRATUS WITH MVFR CIGS WAS
NOTED NORTH OF THE FRONT IMPACTING ALL TERMINALS. ANTICIPATE THE
STRATUS AND MVFR CIGS TO LIFT TO VFR AND SCATTERING AT THE TERMINALS
FROM SOUTH TO NORTH THROUGH 00Z. STATIONARY FRONT IS EXPECTED TO
LIFT BACK NORTH AS A WARM FRONT THROUGH THE TERMINALS LATE TONIGHT
AND MONDAY MORNING. ANTICIPATE MORE LOW CLOUDS AND FOG WITH IFR TO
MVFR CONDITIONS DEVELOPING NORTH OF THE WARM FRONT AS SUGGESTED BY
MOST GUIDANCE INCLUDING HRRR...SREF AND RAP MODEL VSBY/CIG PLOTS.
CONDITIONS TO RETURN TO VFR AT ALL SITES BY 18Z MONDAY AS WARM FRONT
LIFTS NORTH OF THE TERMINALS. WINDS WILL BE EASTERLY AT 5-10 KTS
THIS AFTERNOON AND EVENING... WITH OCCASIONAL GUSTS NEAR 20 KTS POSSIBLE
THIS AFTERNOON. LATE TONIGHT AND MONDAY MORNING AS THE WARM FRONT PASSES
WINDS WILL BECOME SOUTHERLY AROUND 10 KTS WITH SOME GUSTS POSSIBLE LATE
MORNING. RAIN CHANCES ARE NOT ZERO DURING THE PERIOD... BUT APPEAR TOO
SMALL FOR INCLUSION IN TERMINALS.
&&
.CLIMATE...
ISSUED AT 113 AM CDT SUN SEP 8 2013
RECORD HIGHS FOR SEPTEMBER 9...
MOLINE.........99 IN 1933
CEDAR RAPIDS...98 IN 1955
DUBUQUE........97 IN 1955
BURLINGTON.....100 IN 1912
RECORD HIGHS FOR SEPTEMBER 10...
MOLINE.........95 IN 1983
CEDAR RAPIDS...98 IN 1931
DUBUQUE........97 IN 1895
BURLINGTON.....97 IN 1933
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...DLF
AVIATION...05
CLIMATE...DLF
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1158 AM CDT SUN SEP 8 2013
.SHORT TERM.../TODAY /...
ISSUED AT 334 AM CDT SUN SEP 8 2013
THE COLD FRONT HAS PUSHED THROUGH ALL BUT THE FAR SOUTHEAST CORNER
OF IOWA WITH LIGHT NLY WIND OVER THE CWA. WINDS WILL VEER TO NELY
AND EVENTUALLY ELY. LOWERED TEMPS A BIT WITH THE STRONGER PUSH OF
COOLER AIR AND THE PROSPECT FOR MORE CLOUDINESS. AREAS OF CONCERN
ARE THREE FOLD TODAY. FIRST IS THE STRATUS DECK ENTERING NERN IA
THIS MORNING AND HOW FAR IT WILL PUSH TO THE SOUTHWEST. THINKING IS
THAT IT WILL PUSH ABOUT A THIRD OF THE WAY ACROSS THE STATE BEFORE
IT STARTS TO BREAK UP. TEMPS MAY WELL STRUGGLE TO MAKE 80 IN THE
FAR NERN PART OF THE CWA. SECOND CONCERN IS WITH THE MCS OVER THE
DAKOTAS. SPILL OFF CLOUDINESS MAY WELL HAVE A SIGNIFICANT IMPACT ON
TEMPS. THOUGH WE ARE STARTING OUT QUITE WARM...IT WOULD SEEM THAT
FEW PLACES WILL BREAK OUT OF THE 80S...AND THAT WILL BE IN THE FAR
SOUTHWEST. THIRD CONCERN IS THE HRRR DEVELOPMENT OF SHOWER ACTIVITY
OVER WESTERN IA THIS MORNING. DON`T SEE A LOT OF SUPPORT FOR THAT
EVEN GIVEN SOME AC AND VIRGA DEVELOPMENT OVER EASTERN NEBRASKA AT
PRESENT. THERE IS MORE SUPPORT THERE AND IT IS STRUGGLING WITH THE
EML IN PLACE. WITH THAT SAID...WILL GO A TOUGH ABOVE MOS GUIDANCE
FOR HIGHS TODAY. LEFT POPS OUT EXCEPT FOR THE POTENTIAL OF SOME
EARLY MORNING TSRA OVER THE EXTREME SOUTHEAST AS THESE HAVE HAD A
TENDENCY TO BACK DEVELOP THROUGH THE EARLY MORNING HOURS.
.LONG TERM.../TONIGHT THROUGH FRIDAY/...
ISSUED AT 334 AM CDT SUN SEP 8 2013
STRONG WARM ADVECTION WILL PASS THROUGH CENTRAL IOWA LATE TONIGHT
AND THROUGH THE DAY ON MONDAY AS LOW PRESSURE MOVES THROUGH THE
DAKOTAS AND INTO MINNESOTA. A WELL MIXED PROFILE WILL BE IN PLACE
BY THE AFTERNOON FUELED BY BREEZY SOUTHWEST WINDS. DEWPOINTS WILL
DROP INTO THE 50S TO LOWER 60S AS THE PROFILES MIX IN THE
AFTERNOON. HIGH TEMPERATURES WILL JUMP INTO THE MID 90S TO
POSSIBLY LOW 100S BY MID AFTERNOON. THESE READINGS ARE NEAR TO
ABOVE RECORD VALUES. THE CURRENT LATEST 100 DEGREE DAY AT DES
MOINES OCCURRED ON SEPTEMBER 7TH 1939 THEREFORE IF THE FORECAST OF
100 VERIFIES...IT WILL ECLIPSE THAT MARK. BOTH WATERLOO (SEPTEMBER
15TH 1927) AND OTTUMWA (SEPTEMBER 11TH 1936) HAVE HAD 100 DEGREE
DAYS BEYOND THIS POINT.
A FRONTAL BOUNDARY WILL GRADUALLY SAG THROUGH IOWA MONDAY NIGHT
THROUGH TUESDAY NIGHT AS THE AREA OF LOW PRESSURE SHIFTS TO THE
EAST. THE BOUNDARY WILL BE QUITE SLOW TO MOVE SOUTH AS THE UPPER
LEVEL RIDGE STUBBORNLY GIVES WAY TO A SHORT WAVE MOVING EAST ALONG
THE US/CANADIAN BORDER. THE PRIMARY ENERGY WITH THIS SYSTEM WILL
BE PASSING TO THE NORTH OF THE STATE NEAR THE UPPER WAVE AND IN
THE VICINITY OF THE RIGHT REAR QUAD OF THE UPPER JET. THE MAIN
POTENTIAL FOR PRECIPITATION WILL BE POST SFC FRONTAL AND CLOSER TO
THE 850 MB BOUNDARY LATE TUESDAY INTO TUESDAY NIGHT. CONFIDENCE IS
NOT HIGH THAT ANY BENEFICIAL RAIN WILL OCCUR WITH THIS SYSTEM AND
ESPECIALLY IN THE EXPANDING D2 DROUGHT REGION OVER THE CENTRAL AND
WEST CENTRAL AREAS. A TRANSITION TO NORTHWEST FLOW TUESDAY NIGHT
AND WEDNESDAY WILL FINALLY PUSH THE BOUNDARY SOUTH OF THE STATE
AND THIS WILL ALLOW A LARGE CANADIAN HIGH PRESSURE SYSTEM TO DROP
INTO THE UPPER MIDWEST AND WESTERN GREAT LAKES REGION FOR THE END
OF THE WEEK. THE HIGH WILL BRING A REFRESHING BLAST OF COOLER AIR
WITH HIGHS IN THE 70S BY FRIDAY AND OVERNIGHT LOWS POSSIBLE
DROPPING INTO 40S OVER THE NORTH.
&&
.AVIATION...08/18Z
ISSUED AT 1158 AM CDT SUN SEP 8 2013
MVFR CIGS DUE TO STRATUS/STRATOCU WILL TRANSITION TO SCATTERED
CLOUDS THIS AFTN FROM SOUTH TO NORTH...WITH THE KALO AND KMCW
TERMINALS TRANSITIONING THE LATEST. OVERNIGHT...MVFR CIGS ARE
EXPECTED TO RETURN WITH THE BEST CHANCES AT THE NORTHERN TERMINALS.
WARM FROPA OVERNIGHT AND EARLY MON MORNING WILL SHIFT WINDS TO THE
SOUTH AND CLEAR OUT THE CLOUDS FOR MONDAY.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MS SEP 13
LONG TERM...DONAVON
AVIATION...ZOGG
AREA FORECAST DISCUSSION
NWS TOPEKA KS
309 PM CDT Sun Sep 8 2013
.SHORT TERM...(This Evening through Monday)
Issued at 305 PM CDT SUN SEP 8 2013
At 2 PM, a weak surface trough was oriented from east to west across
northern Kansas on Sunday afternoon, co-located with the axis of
warmest 850 temperatures. A very weak front/outflow boundary with
minimal convergence in the low levels was stationary within 30 miles
of the Nebraska border as well, with a cluster of showers and
thunderstorms in extreme northeast Kansas and northwest Missouri.
Temperatures just to the south of the weak surface boundary have
become extremely warm, ranging from 99 to 104 degrees early this
afternoon, and while some drier air has mixed to the surface,
dewpoints remain in the lower to middle 60s. These conditions along
with the expectation for further heating through 4 PM have prompted
issuance of a heat advisory for heat index values in the 104 to 107
range.
Aside from the heat, potential for more vigorous thunderstorm
development is the other forecast focus today. The most recent runs
of the HRRR and NMM models continue to suggest thunderstorm
development on the warm side of the weak surface front by middle to
late afternoon, potentially linked to any outflow moving southwest
out of ongoing convection in NW Missouri. These storms are not
expected to be particularly organized or strong owing to only weak
to moderate CAPE and very weak vertical shear. However, it would
seem to be a rather favorable setup for microbursts given the dry
adiabatic to superadiabatic lapse rates from the surface to 700 hpa
and favorable downdraft CAPE. The primary uncertainty lies in
whether storms will actually develop over the deeply mixed airmass
as parcels would need to be lifted through a very deep mixed layer
before freely convecting. The best chance for storms would seem to
be northeast of a line from Belleville to Junction City to Ottawa.
Any storms should come to an end by 10 PM. Temperatures will fall
off nicely but a south breeze is expected to persist through the
night and will probably keep low temps in the low to mid 70s. Monday
will be quite hot once again, but with the upper ridge progressing
east of the area, 850 temps are forecast to drop by 2 to 3 degrees
from Sunday and highs may hold in the middle to upper 90s. Southwest
winds will be quite a bit stronger than Sunday with an increasing
pressure gradient. The southwest flow should also support greater
dry air advection into the forecast area which will probably support
very high fire danger with any dry vegetation.
Barjenbruch
.LONG TERM...(Monday Night through Sunday)
Issued at 305 PM CDT SUN SEP 8 2013
Monday night upper level trough progresses eastward through the
northern plains. As this system pushes into the Great Lakes region a
cold front will move southward into the region. Temperatures at 850
will cool significantly over the central plains as the shortwave
continues eastward and the upper high shifts into the OH river
valley. High temperatures reach the mid 90s area wide on Tuesday.
The front will approach the cwa on Tuesday evening and there is a
slight chance for showers and thunderstorms along the front mainly
across southern NE with an outside chance of reaching the northern
counties. Overnight Tuesday the front sags south into the cwa
increasing the chances for storms north of interstate 70s as the
progress of the front slows down. Due to cloud cover associated with
the possible precip high temperatures on Wednesday could remain in
the upper 80s to low 90s.
The front continues to slowly push south across the cwa therefore
have maintains pops through Friday. Convergence along the front and
upper level forcing appears to be rather weak, but cooler mid level
temps will allow for a weaker cap in place. Front exits the area
sometime on Thursday night or Friday as a shortwave digs southeast
through the eastern longwave trough. A surface high pressure will
build northeast of the region and likely control how far the front
is pushed southward. Once the front passes return flow isentropic
lift may generate precip mainly across central and western KS
possible spreading into our western counties. Next weekend another
front will possibly move into the central plains. Temperatures look
to gradually cool behind the front with high temperatures in the
upper 70s to low 80s by Friday, and low temperatures generally in
the upper 50s to low 60s.
&&
.AVIATION...(For the 18Z TAFs through 18Z Monday Afternoon)
Issued at 1202 PM CDT SUN SEP 8 2013
Expect VFR conditions with scattered clouds based around 12000
feet, and a light southwest breeze less than 10 kts. There is a
small chance for TS to develop near TOP/FOE...and perhaps as far
west as MHK...between 19Z and 22Z. If TS are able to develop, very
localized areas of strong and variable downburst winds would be
possible in close proximity to storms.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY until 7 PM CDT this evening FOR KSZ021>024-026-036-
038>040-054>056-058-059.
&&
$$
SHORT TERM...Barjenbruch
LONG TERM...Sanders
AVIATION...Barjenbruch
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
335 PM EDT SUN SEP 8 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 335 PM EDT SUN SEP 8 2013
18Z SFC ANALYSIS SHOWS A COLD FRONT DISSIPATING OVER EAST KENTUCKY.
THIS BOUNDARY HAS NOT BROUGHT AN AIR MASS CHANGE AND HAS NOT BEEN
ABLE TO GENERATE MUCH IN THE WAY OF CONVECTION FOR EAST KENTUCKY...SO
FAR. HOWEVER...THERE ARE A FEW SHOWERS GOING UP NOT TOO FAR FROM
US. STILL THINK THAT A SOME SHOWERS AND POSSIBLY A THUNDERSTORM WILL
OCCUR OVER PARTS OF EAST KENTUCKY...MAINLY SOUTH OF JKL...THROUGH
SUNSET. SKIES HAVE BEEN PARTLY TO MOSTLY CLOUDY THROUGH THE AREA THIS
AFTERNOON WITH THE SUNSHINE HELPING TEMPERATURES CLIMB INTO THE LOWER
AND MID 80S IN MOST LOCATIONS. MEANWHILE...DEWPOINTS HAVE SLIPPED A
BIT...MIXING DOWN TO THE LOW TO MID 60S THOUGH THE WINDS HAVE BEEN
GENERALLY LIGHT.
THE MODELS ARE IN GOOD AGREEMENT ALOFT WITH A SMALL SHORTWAVE PASSING
BY TO THE NORTHEAST TONIGHT...WHILE AN MCV WILL SLIP SOUTH WELL TO
THE WEST OF THE AREA. RIDGING THEN BUILDS BACK OVER THE AREA EARLY
MONDAY...RUNNING EAST OVER KENTUCKY DURING THE DAY AND INTO THE
NIGHT. WITH THE GOOD MODEL AGREEMENT...HAVE AGAIN FOLLOWED THE HIGHER
RESOLUTION NAM12 FOR DETAILS...ALONG WITH SOME HRRR INFLUENCE IN THE
NEAR TERM.
SENSIBLE WEATHER WILL FEATURE WIDELY SCATTERED SHOWERS AND THE ODD
THUNDERSTORM...FADING OUT BY SUNSET ALONG WITH MUCH OF THE CLOUDS.
THIS WILL SET THE STAGE FOR ANOTHER MILD NIGHT WITH PATCHY FOG
DEVELOPING TOWARD DAWN...MAINLY IN THE VALLEYS. THE RIDGE BUILDING
ALOFT ON MONDAY WILL WIPE OUT THE REMAINS OF THE FRONT AND LIMIT ANY
CONVECTION TO JUST A VERY SMALL THREAT ALONG THE VIRGINIA BORDER AT
PEAK HEATING. IT WILL ALSO BE A VERY WARM DAY WITH TEMPERATURES
APPROACHING 90 DEGREES IN SOME LOCATIONS BY LATE AFTERNOON. ANOTHER
MILD NIGHT WITH PATCHY VALLEY FOG FOLLOWS INTO TUESDAY MORNING.
AGAIN USED THE CONSSHORT AND ITS BIAS CORRECTED KIN TO JUMP START
THE TD AND WIND GRIDS THROUGH 12Z MONDAY AND THE CONSALL THEREAFTER.
FOR TEMPERATURES...PREFERRED THE OBS DATABASE AS A BASIS FOR THE
DIURNAL CURVE AND MODIFIED CONSALL FOR MAX AND MIN TEMPS. AGAIN DID
NOT DO TOO MUCH TERRAIN ADJUSTMENT AT NIGHT GIVEN THE HIGHER DEWS AND
SOME CLOUD COVER EXPECTED TO BE AROUND. AS FOR POPS...ENDED UP PRETTY
CLOSE TO AN AVERAGE OF THE GUIDANCE THROUGH THE SHORT TERM PERIOD.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 320 PM EDT SUN SEP 8 2013
THE MODELS WERE NOT IN THE BEST AGREEMENT THIS TIME AROUND WITH THE
SURFACE DETAILS. THE UPPER AIR PATTERN...HOWEVER...WAS GENERALLY THE
SAME BETWEEN THE HPC...GFS...ECWMF MODEL OUTPUTS. THE PERIOD IS
PROGGED TO START OUT WITH A LARGE RIDGE OF HIGH PRESSURE PARKED
ACROSS THE SOUTHEASTERN CONUS. WEAK MARGINALLY MOIST FLOW AROUND THE
WESTERN EDGE OF THE HIGH COULD LEAD TO ISOLATED SHOWER AND STORM
ACTIVITY TUESDAY AFTERNOON AND EVENING. THE GFS AND SREF WERE ALSO
ON BOARD WITH THIS PATTERN. BASED ON THE LATEST MEXMOS AND ECEMOS
GUIDANCE...THERE WOULD BE A CHANCE OF RAIN IN THE FORECAST EACH DAY
FROM TUESDAY THROUGH THURSDAY NIGHT. THAT BEING SAID...AND WITH THE
LATEST RUNS OF THE GFS AND ECWMF BOTH IN GOOD AGREEMENT...DECIDE TO
INCLUDE A CHANCE OF RAIN IN THE FORECAST THROUGH LATE THURSDAY
NIGHT. THE BEST CHANCE FOR RAIN LOOKS TO BE THURSDAY AND THURSDAY
EVENING...AS A FAIRLY STRONG COLD FRONT MOVES ACROSS THE AREA.
TEMPERATURES AHEAD OF THE FRONT WILL BE QUITE WARM...WITH HIGHS
TOPPING OUT IN THE MID TO UPPER 80S ACROSS THE AREA TUESDAY THROUGH
THURSDAY. EASTERN KENTUCKY WILL BE ENTRENCHED IN A PERSISTENT
SOUTHERLY FLOW REGIME AS AN AREA OF HIGH PRESSURE REMAINS IN PLACE
ACROSS THE AREA. THE PRESENCE OF CLOUDS AND ISOLATED SHOWERS AND
STORMS SHOULD BE ENOUGH TO KEEP TEMPERATURES AROUND EASTERN KENTUCKY
FROM REACHING THE EXTREMELY WARM MOS VALUES(THE LATEST MEXMOS HAS A
FEW LOCATIONS AROUND THE AREA REACHING THE LOWER 90S ON TUESDAY). A
DRAMATIC COOL DOWN IS IN STORE FOR THE END OF THE WEEK...AS A COOL
AND DRY CANADIAN AIR MASS SETTLES OVER THE AREA BEHIND THE DEPARTING
COLD FRONT. DAYTIME HIGHS ON FRIDAY AND SATURDAY WILL NOT GET OUT
OF THE 70S...WITH HIGHS ON SATURDAY POSSIBLE ONLY MAKING IT INTO THE
LOW TO MID 70S. OVERNIGHT LOWS WILL BE QUITE WARM AT FIRST...WITH
VALUES AROUND 70 COMMON TO START THE PERIOD. THINGS WILL COOL OFF
QUITE A BIT AFTER THAT...WITH LOWS AROUND 60 POSSIBLE THURSDAY
NIGHT...AND DROPPING INTO THE LOWER 50S FRIDAY NIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 200 PM EDT SUN SEP 8 2013
A DISSIPATING COLD FRONT WILL BRING A SMALL THREAT OF CONVECTION TO
THE AREA THIS AFTERNOON. FOR THIS...HAVE INCLUDED SOME VCSH IN THE
TAFS. ONCE WE LOSE THE DAYTIME HEATING...SKIES WILL CLEAR OUT WITH
SOME MVFR FOG LIKELY SEEN ONCE AGAIN BETWEEN 06 AND 12Z AT THE TAF
SITES...LOCALLY DENSE THOUGH IN THE EASTERN VALLEYS. CANNOT RULE OUT
A STRAY SHOWER OR THUNDERSTORM ON MONDAY...THOUGH THEY WILL LIKELY BE
FEW AND FAR BETWEEN. WINDS WILL BE LIGHT AND VARIABLE THROUGHOUT THE
PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GREIF
LONG TERM...AR
AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
200 PM EDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 155 PM EDT SUN SEP 8 2013
SHOWERS ARE STARTING TO DEVELOP OVER THE CUMBERLAND VALLEY BUT ARE
STILL RATHER ISOLATED. HAVE UPDATED THE GRIDS MAINLY FOR NEAR TERM
POPS...SKY COVER...AND TO MATCH UP THE T/TD ONES TO THE OBS AND
TRENDS. UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS.
UPDATE ISSUED AT 1100 AM EDT SUN SEP 8 2013
14Z SFC ANALYSIS SHOWS A WEAK COLD FRONT POISED TO DROP THROUGH EAST
KENTUCKY TODAY. A SMATTERING OF LIGHT SHOWERS MOVED ACROSS THE AREA
EARLY IN THE MORNING OUT AHEAD OF THIS...ALONG WITH PATCHY FOG...AND
SKIES HAVE TEMPORARILY CLEARED IN THEIR WAKE. TEMPERATURES AND
DEWPOINTS ARE FAIRLY UNIFORM THROUGH THE AREA GENERALLY IN THE LOWER
70S AND UPPER 60S...RESPECTIVELY. THE LATEST NAM12 AND HRRR INDICATE
THAT THE SOUTHERN PARTS OF THE CWA WILL HAVE THE BEST CHANCE OF
SEEING A REDEVELOPMENT OF SHOWERS AND ISOLATED STORMS BY MID
AFTERNOON AS THE FRONT SETTLES ON THROUGH. HAVE GEARED THE NEAR TERM
FORECAST GRIDS TO THIS IDEA...ALLOWING THE INSTABILITY TO BUILD
BEFORE INTRODUCING THUNDER INTO THE WX ONES. MOST PLACES WILL STAY
DRY...WARM..AND HUMID TODAY...THOUGH. A FORTHCOMING ZFP UPDATE WILL
REMOVE THE MORNING FOG WORDING. THE FRESHENED GRIDS HAVE BEEN SENT TO
THE NDFD AND WEB SERVERS.
UPDATE ISSUED AT 657 AM EDT SUN SEP 8 2013
ISOLATED SHOWERS ARE DIMINISHING ACROSS THE AREA AS THE ISENTROPIC
FORCING EASES UP. WILL LET THE FORECAST RIDE AS A FEW SHOWERS MAY BE
SEEN AFTER 12Z BEFORE DRYING UP COMPLETELY UNTIL WE HEAT UP THIS
AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 254 AM EDT SUN SEP 8 2013
THE LATEST SURFACE MAP FEATURES A SURFACE COLD FRONT ALIGNED FROM
NORTHERN NEW ENGLAND DOWN THROUGH THE NORTHERN OHIO VALLEY...WITH AN
AREA OF SURFACE HIGH PRESSURE CONGEALED ACROSS THE SOUTHEASTERN
CONUS. ISENTROPIC LIFT OUT AHEAD OF THE FRONT HAS ALLOWED FOR SOME
NOCTURNAL SHOWER ACTIVITY ALONG AND SOUTH OF THE OHIO
RIVER...INCLUDING PORTIONS OF EASTERN KENTUCKY. THE LATEST NAM12
SEEMS TO HAVE A REASONABLE HANDLE ON THE ISENTROPIC LIFT...ALTHOUGH
ITS QPF IS NOT BEEFY ENOUGH COMPARED TO REALITY.
THE MODELS REMAIN IN GOOD AGREEMENT THROUGH THE SHORT TERM...ALLOWING
THE COLD FRONT TO MAKE IT INTO THE COMMONWEALTH THIS AFTERNOON. POPS
HAVE COME IN LOWER...ESPECIALLY FROM THE NAM12. WILL STICK WITH AT
LEAST ISOLATED CHANCES...ALTHOUGH WILL RESTRICT THE SCATTERED
POTENTIAL TO THE SOUTHEAST TERRAIN COUNTIES GIVEN THE DOWNWARD TREND.
HIGHS WILL BE A BIT WARMER THAN YESTERDAY...WITH MID 80S FOR MOST
LOCATIONS...AND A FEW SPOTS REACHING THE UPPER 80S.
THE FRONT WILL DISSOLVE ACROSS THE AREA INTO THIS EVENING...AND
EXPECT A QUICK DIE OFF IN THE CONVECTION WITH THE LOSS OF HEATING.
LOWS TONIGHT WILL REFLECT THE INCREASING HUMIDITY ACROSS THE
AREA...WITH MID TO UPPER 60S EXPECTED. AN UPPER LEVEL RIDGE WILL MOVE
IN FROM THE WEST ON MONDAY...SO EXPECT THIS TO KEEP A LID ON THE
CONVECTION FOR THE MOST PART...ALTHOUGH COULD SEE A STRAY SHOWER OR
STORM GO UP ALONG THE SOUTHEAST TERRAIN. HIGHS WILL BE A BIT WARMER
STILL...WITH UPPER 80S EXPECTED AND A FEW SPOTS FLIRTING WITH THE 90
DEGREE MARK.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 346 AM EDT SUN SEP 8 2013
THE MODELS START OUT IN GOOD AGREEMENT WITH AND UPPER RIDGE OVER THE
SOUTHEAST WITH AN UPPER TROUGH MOVING EAST ACROSS THE ROCKIES. THERE
IS A BATTLE OF SORTS WITH THE UPPER RIDGE WHICH TRIES TO STAY IN
PLACE AS THE TROUGH TRIES TO DISPLACE IT. BY WEDNESDAY MORNING A COLD
FRONT EXTENDS FROM ACROSS LAKE HURON AND ENDS OVER COLORADO. THE UPPER
RIDGE IS DISPLACED A LITTLE EASTWARD. ALL THIS WHILE...SOME WARM
MOIST AIR IS WORKING ITS WAY INTO THE AREA. THIS WARM MOIST AIR WILL
BE RESPONSIBLE FOR SOME ISOLATED SHOWERS AND THUNDERSTORMS ON TUESDAY
AND THEN SOME SCATTERED STORMS ON WEDNESDAY AFTERNOON AND EVENING.
THE FRONT WILL BE MOVING ACROSS THE AREA ON THURSDAY. CHOSE TO GO
WITH THE SLOWER ECMWF MODEL FOR THE TIMING OF THE FRONT. THE FRONT
WILL BRING A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS TO THE AREA.
THE FRONT WILL BE THROUGH THE AREA BY FRIDAY MORNING AND A SURFACE
HIGH PRESSURE SYSTEM WILL MOVE IN AND DOMINATE UNTIL THE END OF THE
PERIOD. THE OUTLOOK FOR NEXT WEEKEND IS GOOD WITH DRY CONDITIONS AND
HIGH TEMPERATURES IN THE 70S. FOR TEMPS TENDED TO NUDGE TOWARD THE
COOLER MODELS FOR THE HIGH TEMPERATURES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 200 PM EDT SUN SEP 8 2013
A DISSIPATING COLD FRONT WILL BRING A SMALL THREAT OF CONVECTION TO
THE AREA THIS AFTERNOON. FOR THIS...HAVE INCLUDED SOME VCSH IN THE
TAFS. ONCE WE LOSE THE DAYTIME HEATING...SKIES WILL CLEAR OUT WITH
SOME MVFR FOG LIKELY SEEN ONCE AGAIN BETWEEN 06 AND 12Z AT THE TAF
SITES...LOCALLY DENSE THOUGH IN THE EASTERN VALLEYS. CANNOT RULE OUT
A STRAY SHOWER OR THUNDERSTORM ON MONDAY...THOUGH THEY WILL LIKELY BE
FEW AND FAR BETWEEN. WINDS WILL BE LIGHT AND VARIABLE THROUGHOUT THE
PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...GEOGERIAN
LONG TERM...JJ
AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS GAYLORD MI
159 PM EDT SUN SEP 8 2013
.SYNOPSIS...
ISSUED AT 304 AM EDT SUN SEP 8 2013
HIGH PRESSURE PUSHING INTO THE STATE IS BRINGING WITH IT
SIGNIFICANTLY COOLER AND DRIER AIR TODAY. THE WARM AIR WILL
BEGIN TO RETURN MONDAY AS A WARM FRONT MOVES TOWARDS THE REGION.
THIS WILL BRING RENEWED CHANCES FOR SHOWERS AND THUNDERSTORMS.
WARM AND MUGGY CONDITIONS WILL PERSIST INTO TUESDAY BEFORE ANOTHER
COLD FRONT ARRIVES LATE TUESDAY. MUCH COOLER AIR WILL MOVE INTO
NORTHERN MICHIGAN TO END THE WEEK.
&&
.UPDATE...
ISSUED AT 105 PM EDT SUN SEP 8 2013
NO CHANGES TO THE FORECAST...STRATOCUMULUS THAT HAS FORMED THIS
MORNING HAS MIXED OUT AS EXPECTED...WITH JUST SOME HIGH CLOUDS
POURING INTO THE REGION FOR THIS AFTERNOON. TEMPERATURES LOOK TO
REMAIN ON TRACK...WITH LIGHTER EASTERLY FLOW COMPARED TO THIS
MORNING AS THE PRESSURE GRADIENT HAS SLACKENED AND HAS PUSHED TO
THE SOUTH.
UPDATE ISSUED AT 939 AM EDT SUN SEP 8 2013
CHANGES THIS HOUR: PRIMARY CHANGES WILL BE TO CLOUD COVER THROUGH
THE DAY...WITH RECENT OBSERVATIONS AND NEAR TERM RAP BUFR PROGS
SUGGESTING THAT WE/LL BUBBLE UP A BIT OF STCU BEFORE A GRADUAL
CLEARING TREND TAKES PLACE THIS AFTERNOON. OVERALL...THIS RESULTS
IN PRETTY MINOR CHANGES TO THE GOING FORECAST...WITH A PARTLY
SUNNY DAY EXPECTED FOR MOST. TEMPS LOOK ON TRACK TO REACH WITHIN A
FEW DEGREES OF THE 70F MARK.
UPDATE ISSUED AT 645 AM EDT SUN SEP 8 2013
STRONG HIGH PRESSURE...SUBSIDENCE AND DRY AIR THRU THE COLUMN
CONTINUES TO BUILD SOUTHWARD OUT OF ONTARIO AND INTO MICHIGAN
EARLY THIS MORNING. A FEW LOW CLOUDS REMAIN ACROSS FAR SRN
SECTIONS OF OUR CWA...BUT THOSE CLOUDS WILL SLIDE FURTHER SOUTH AS
DRIER AIR CONTINUES TO BUILD SOUTHWARD. ALSO...THE START OF
DAYTIME HEATING WILL LEND TO THE DISSIPATION OF RESIDUAL LOW
CLOUDS THRU DIURNAL MIXING ONCE THE SUN RISES. THE REST OF THE DAY
WILL BE SUNNY BUT NOT AS WARM AND HUMID AS YESTERDAY. HIGH TEMPS
THIS AFTERNOON WILL ONLY WARM INTO THE MID 60S TO LOWER 70S.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 304 AM EDT SUN SEP 8 2013
CURRENTLY, THE 500 MB RIDGE TO THE WEST LOOKS TO BE IN THE
BEGINNING STAGES OF FLATTENING AT THE LEAST AS THE WESTERN CUTOFF
LOW PUSHES INTO THE PAC NORTHWEST. TO THE EAST THE 500 MB TROUGH
LOOKS TO BE HOLDING IN PLACE. THIS SETS UP THE UPPER GREAT LAKES
FOR NORTHWEST FLOW/WARM ADVECTION PATTERN OVER THE NEXT COUPLE OF
DAYS. HOWEVER, IT THE VERY NEAR TERM (TODAY/TONIGHT), HIGH
PRESSURE WILL BE THE DOMINATE FEATURE.
TODAY...THE DRIER AIR, AS NOTED IN PREVIOUS UPDATES, IS MAKING ITS
WAY INTO THE N LOWER NOW, AS EVIDENT ON THE IR IMAGE. THE CLEARING
LINE HAS MADE IT TO ROUGHLY TO A LINE FROM APN TO FKS. THERE WAS A
CONCERN AT THE OUTSET OF THE EVENING FOR FOG, FROM THE RATHER
SOUPY AIR MASS THAT WAS LEFT FROM THE INITIAL SFC TROUGH. HOWEVER,
A SECOND, WEAKER TROUGH, USHERED IN THE DRIER, AND "BREEZIER"
AIR MASS. WITH THE WINDS OVER LAND, FROM THE TIGHTER GRADIENT,
HOLDING AROUND 5 TO 10 KNOTS, THIS HAS KEPT THE FOG FROM FORMING,
AND LEFT LOW CLOUDS BEHIND THE BOUNDARY. NOW THE DRY AIR AT 850 MB
AND BELOW IS PUSHING INTO THE REGION AND CLEARING THE FORECAST
AREA. BY DAYBREAK, IT LOOKS LIKE WE WILL GET MOSTLY SUNNY SKIES,
WITH ONLY THE CIRRUS BLOW OFF FROM THE MCS IN DAKOTAS, WHICH
SHOULD MOVE SOUTHEAST IN THE COMING HOURS, MISSING MICHIGAN.
TONIGHT...THE HIGH WILL TRANSIT THE FORECAST AREA DURING THE DAY,
SO THAT IN THE EVENING, THE RETURN FLOW WILL START IN NW LOWER.
TEMPERATURES THERE SHOULD IN THE 50S, WHILE IN NE LOWER AND E
UPPER THE WINDS WILL DECOUPLE FOR A TIME WHILE THE CORE OF THE
HIGH EXITS AND ALLOW SOME RADIATIONAL COOLING. TEMPERATURES WILL
FALL INTO THE UPPER 40S BEFORE HOLDING FROM THE RETURN FLOW AND
THE INCREASING CLOUDS FROM THE WARM FRONT BEGINNING TO FORM. THE
NAM AND GFS KEEP THE REGION DRY THROUGH 12Z AS THE BETTER
ISENTROPIC FORCING REMAINS UPSTREAM IN THE MINNESOTA ARROWHEAD.
THE ECMWF SEEMS THE OUTLIER WITH THE MOISTURE SOMEWHAT MORE
AGGRESSIVELY MOVING INTO LOWER MICHIGAN BY 12Z. CONSIDERING THAT
ALL THE MODELS HAVE THE SAME BASIC SCENARIO OF THE HIGH MOVING
TOWARD THE SE, AND THAT THE RETURN FLOW FROM A HIGH RETREATING IN
THAT DIRECTION USUALLY TAKES A LITTLE LONGER FOR THE RETURN FLOW
TO PUSH MOISTURE INTO THE STATE, THINK THAT THE GFS/NAM IDEA IS
RIGHT, SO HAVE THE RAIN STAYING OFF TO THE WEST THROUGH 12Z.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 304 AM EDT SUN SEP 8 2013
MONDAY THRU TUESDAY...SURFACE HIGH CENTER WILL SHIFT EAST OF OUR
STATE LATE SUNDAY NIGHT...WITH RETURN MOIST SOUTHERLY FLOW QUICKLY
KICKING IN EARLY MONDAY. A WARM FRONT ASSOCIATED WITH LOW PRESSURE
DEVELOPING IN THE NRN PLAINS WILL LIFT NE INTO NRN MICHIGAN ON
MONDAY. CHANCES OF SHOWERS AND STORMS WILL INCREASE...ESPECIALLY
ACROSS UPR AND FAR NRN LWR MICHIGAN AS DEEP MOISTURE POOLS AROUND
AND NORTH OF THE WARM FRONT. GREATEST CHANCE OF PRECIP WILL DEVELOP
MONDAY NIGHT AS THE SURFACE LOW CENTER TRACKS ALONG THE WARM FRONT
THRU THE STRAITS. THE ASSOCIATED COLD FRONT WILL SLOWLY SLIDE THRU
OUR CWA TUESDAY AND TUESDAY NIGHT. FOCUS OF CONVECTIVE DEVELOPMENT
WILL GENERALLY FOLLOW THIS BOUNDARY... GRADUALLY SHIFTING HIGHEST
POPS FROM ERN UPR AND FAR NRN LWR MICHIGAN ON TUESDAY SOUTHWARD TO
ALL OF NRN LWR MICHIGAN FOR TUESDAY NIGHT. TEMPS WILL RESPOND TO
STRENGTHENING WAA SOUTH OF THE WARM FRONT AND AHEAD OF THE COLD FRONT
BOTH MONDAY AND TUESDAY. HIGH TEMPS MONDAY AFTERNOON WILL WARM WELL
INTO THE 70S ACROSS NRN LWR MICHIGAN SOUTH OF THE WARM FRONT...AND
AROUND 70 ACROSS ERN UPR MICHIGAN WITHIN THICKER CLOUDS AND BETTER
PRECIP CHANCES ALONG THE WARM FRONT. HIGH TEMPS TUESDAY AFTERNOON
WILL VARY GREATLY ACROSS OUR CWA AS THE COOL FRONT SLIDES
THRU...RANGING FROM THE MID TO UPPER 70S IN ERN UPR MICHIGAN TO
AROUND 90 NEAR SAGINAW BAY.
WEDNESDAY THRU SATURDAY...BROAD DEEP CYCLONIC FLOW WILL LINGER ACROSS
THE WRN GREAT LAKES REGION IN THE WAKE OF THE COLD FRONT WEDNESDAY
INTO THURSDAY...AS WILL SOME LIMITED MOISTURE. LOW LEVEL CONVERGENCE
VIA THE CYCLONIC FLOW AND POCKETS OF MOISTURE WILL KEEP SMALL
CHANCES OF SHOWERS IN THE FORECAST THRU THURSDAY. CAA BEHIND THE
FRONT WILL DROP HIGH TEMPS BACK INTO THE 70S ON WEDNESDAY. A
STRONGER COLD FRONT WILL MOVE THRU THE WRN GREAT LAKES ON
THURSDAY...DROPPING TEMPS TO BELOW NORMAL LEVELS FOR THE LAST PART
OF THE WEEK. HIGH TEMPS ON THURSDAY WILL RANGE FROM THE MID 60S IN
ERN UPR MICHIGAN TO THE LOWER 70S IN OUR SE CWA. HIGH TEMPS ON
FRIDAY WILL STRUGGLE TO WARM OUT OF THE 50S ACROSS ERN UPR
MICHIGAN...AND WILL BE MAINLY IN THE LOWER 60S ACROSS NRN LWR
MICHIGAN. LATEST ECMWF IS TRENDING COLDER FOR FRIDAY...DROPPING 850
MB TEMPS TO -2 C ACROSS OUR FAR NRN CWA. COLD CANADIAN SURFACE HIGH
CENTER WILL MOVE OVERHEAD FRIDAY NIGHT/EARLY SATURDAY. THIS COLD
AIRMASS COMBINED WITH CLEARING SKIES AND LIGHT/CALM WINDS WILL
LIKELY RESULT IN SOME PATCHY FROST DEVELOPING LATE FRIDAY NIGHT INTO
EARLY SATURDAY. SATURDAY WILL BE ANOTHER COOL DAY...WITH HIGHS ONLY
IN THE 60S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 154 PM EDT SUN SEP 8 2013
VFR CONDITIONS WILL CONTINUE FOR ALL TAF SITES THROUGH THIS
AFTERNOON INTO TONIGHT...WITH HIGH PRESSURE IN CONTROL. WINDS WILL
REMAIN LIGHT OUT OF THE EAST TO NORTHEAST. FOG POTENTIAL TONIGHT
AT THIS POINT APPEARS LOW...AS WINDS WILL STRUGGLE TO DECOUPLE
DESPITE INCREASING MOISTURE OVER NORTHWEST LOWER. WILL LEAVE ANY
FOG MENTION OUT OF THE TAFS FOR NOW AND CONTINUE TO MONITOR TRENDS
THROUGH THE AFTERNOON.
&&
.MARINE...
ISSUED AT 304 AM EDT SUN SEP 8 2013
SMALL CRAFT WINDS ARE EXPECTED THROUGH THE MORNING AS THE GRADIENT
WON`T SLACKEN OVER THE LAKES UNTIL THE AFTERNOON. WINDS WILL
CONTINUE TO FALL OFF AS THE HIGH TAKES CONTROL THROUGH TONIGHT.
WINDS AND WAVES WILL INCREASE ON MONDAY AND MONDAY NIGHT AS THE
SFC LOW APPROACHES THE REGION.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LHZ348-
349.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...NS
SYNOPSIS...JL
SHORT TERM...JL
LONG TERM...MR
AVIATION...NS
MARINE...JL
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
135 PM EDT SUN SEP 8 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 520 AM EDT SUN SEP 8 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE OVER NW CANADA AND
A TROF OVER ERN NAMERICA. STRONG SHORTWAVE DIVING SE TOWARD NEW
ENGLAND HAS RESULTED IN AMPLIFICATION OF THE ERN TROF OVER THE LAST
24HRS. UPSTREAM...MID LEVEL LOW THAT HAS BEEN OVER THE PACIFIC NW
OVER THE LAST FEW DAYS HAS MOVED LITTLE. CENTER IS CURRENTLY OVER
FAR NE WA. DOWNSTREAM OF THIS FEATURE...TAP OF SUBTROPICAL MOISTURE
EXTENDING INTO THE NRN ROCKIES HAS BEEN AIDING CLUSTERS OF SHRA/TSRA
ACROSS WY/MT INTO THE DAKOTAS. CLOSER TO HOME...IN THE WAKE OF THE
SHORTWAVE MOVING TOWARD NEW ENGLAND...SFC HIGH PRES HAS SETTLED OVER
NRN ONTARIO. FEED OF DRIER AIR ASSOCIATED WITH THE HIGH RESULTED IN
LOW CLOUDS/FOG ACROSS PORTIONS OF UPPER MI CLEARING OUT LAST
EVENING. EARLY THIS MORNING...ONLY SOME THIN CI BLOWOFF FROM
CONVECTION WELL TO THE W IS SPILLING INTO THE UPPER LAKES.
FCST AREA TODAY WILL BE UNDER THE INFLUENCE OF HIGH PRES MOVING SE
FROM NORTHERN ONTARIO. CU RULE SUGGESTS SCT CU SHOULD DEVELOP FOR A
TIME THIS MORNING/EARLY AFTN...SIMILAR TO WHAT WAS OBSERVED N/NW OF
LAKE SUPERIOR YESTERDAY. OTHERWISE...WILL PROBABLY CONTINUE TO SEE
SOME MAINLY THIN CI ACROSS THE FCST AREA TODAY. TEMPS WILL BE ON THE
COOL SIDE OF NORMAL DESPITE SUNSHINE. MIXING TO THE INVERSION BASE
ON FCST SOUNDINGS YIELDS HIGH TEMPS NEAR 70 AWAY FROM THE MODERATING
INFLUENCE OF THE GREAT LAKES. THIS LINES UP WELL WITH OBSERVED HIGHS
UPSTREAM YESTERDAY.
TONIGHT...MIDLEVEL LOW CURRENTLY OVER NE WA WILL BEGIN TO OPEN UP
AND DRIFT E INTO MT. WHILE THIS FEATURE WILL STILL BE TOO FAR W TO
BE A FACTOR HERE...MODELS SHOW WEAKER SHORTWAVES LIFTING NE AHEAD OF
THE LOW AND AROUND WEAKENING CNTRL CONUS RIDGE. AS IN RECENT DAYS...
FCST DILEMMA IS WHETHER ANY OF THESE WEAKER SHORTWAVES WILL BE ABLE
TO SPREAD PCPN INTO THE FCST AREA TONIGHT. THE ECMWF CONTINUES TO BE
MOST AGGRESSIVE SPREADING PCPN INTO THE UPPER LAKES. IN FACT...THE
00Z RUN IS MOST AGGRESSIVE AS IT SPREADS PCPN ACROSS THE ENTIRE FCST
AREA TONIGHT. MEANWHILE...OTHER MODELS WHICH HAD SUPPORTED A FASTER
EWD PUSH OF PCPN (UKMET IN PARTICULAR) HAVE BACKED OFF. GIVEN THE
RATHER SHARP ERN TROF...BELIEVE THE ECMWF IS PROBABLY TOO FAST
DRIVING PCPN EWD. 03Z SREF PROBABILITY OF AT LEAST 0.01 INCH OF PCPN
TONIGHT ONLY REACHES AROUND 20PCT OVER THE FAR W. SINCE BULK OF
GUIDANCE PAINTS A SIMILAR PICTURE TO THE SREF...WILL BASICALLY
MAINTAIN FCST CONTINUITY WITH THE LAST SEVERAL FCSTS AND ONLY BRING
SCHC POPS INTO THE W OVERNIGHT. OTHERWISE...SOUTHERLY RETURN FLOW OF
WARMER/MOISTER AIR AND AN INCREASE IN CLOUDS WILL RESULT IN A WARMER
NIGHT MOST AREAS...ESPECIALLY OVER THE W WHERE GRADIENT WILL BE
TIGHTENING FIRST AND WHERE THICKER CLOUDS WILL ARRIVE EARLIEST.
LINGERING DRY AIR MASS IN THE EVENING COMBINED WITH INITIALLY MOSTLY
CLEAR SKIES AND LIGHT WIND OVER THE E MAY ALLOW TEMPS AT TRADITIONAL
INTERIOR COLD SPOTS TO FALL INTO THE LWR 40S. ONE SIDE ISSUE THAT
MAY ARISE TONIGHT IS THE POTENTIAL FOR LOW CLOUDS AND/OR FOG OVER
THE E. IF SOUTHERLY WINDS UP LAKE MICHIGAN INCREASE SUFFICIENTLY...
LOW CLOUDS AND/OR FOG WILL DEVELOP AS HIGHER DWPT AIR OFF THE LAKE
ADVECTS INTO THE CHILLY INTERIOR. WILL BE SOMETHING TO WATCH FOR.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 535 AM EDT SUN SEP 8 2013
AT 12Z MONDAY UPPER MI WILL BE UNDER THE INFLUENCE OF THE 500MB
RIDGE...STRETCHING ACROSS MUCH OF THE S CENTRAL AND SE U.S. OUR EYES
WILL BE ON THE 500MB TROUGH OVER MT/ID/WY...WHICH WILL SUPPRESS THE
RIDGE TO OUR S AS THE TROUGH PUSHES TOWARD THE UPPER GREAT LAKES.
WARM FRONT WILL SURGE TO OUR N MONDAY MORNING...BEING THE FOCUS OF
SHRA/TSRA DURING THE DAY. THERE REMAINS SOME SIGNIFICANT
DISCREPANCIES ON THE TIMING WHEN COMPARING AVAILABLE MODELS. WHILE
THE NAM/GFS/CANADIAN MODELS KEEP BASICALLY ALL OF THE LAND
/EXCLUDING THE KEWEENAW PENINSULA/ DRY ON MONDAY...THE GENERALLY
FAVORED ECMWF HAS A SOLID 0.25IN OR MORE OVER THE ENTIRE LAND. HAVE
CONTINUED TO UTILIZE A MODEL CONSENSUS APPROACH...WHICH LEADS TO
AROUND 0.5 TO 1IN OF QPF FROM LATE TONIGHT THROUGH TUESDAY OVER THE
KEWEENAW PENINSULA...AND E AREAS N OF A LINE FROM MUNISING THROUGH
NEWBERRY. EXPECT MUCH OF THE STRONGER STORMS TO FOLLOW THE COLD
FRONT FARTHER TO OUR S...WITH LIGHTNING AND HEAVY RAIN BEING THE
MAIN THREATS FOR OUR CWA. AS FOR NON-PRECIP TALK...THE WAA WILL
RESULT IN A WARM NIGHT MONDAY NIGHT...APPROX 15F ABOVE NORMAL FOR
THIS TIME OF YEAR. THIS WILL BE THANKS TO WARM S WINDS REAMING UP
THROUGH THE NIGHT.
IT LOOKS TO BE A VERY ACTIVE AT 500MB FROM TUESDAY MORNING THROUGH
THE END OF THE WORK WEEK. THE INITIAL KICKER OF A SHORTWAVE WILL
PUSH W TO E ACROSS THE CWA TUESDAY AS THE SFC LOW EXITS E LAKE
SUPERIOR INTO SE QUEBEC. THIS WILL TIME OUT WITH THE RIGHT REAR
QUADRANT OF THE 250MB JET.
ALTHOUGH NOT A THREAT OF THUNDERSTORMS WILL BE DONE AFTER TUESDAY
AFTERNOON...THE EXTENDED SECTION OF THE FCST IS NOT WITHOUT
SIGNIFICANCE. LOOK FOR THE NEXT 500MB TROUGH TO SWING THROUGH MID
WEEK. WHILE NOT A SIGNIFICANT RAIN MAKER...IT WILL MARK THE START OF
SIGNIFICANTLY COOLER WEATHER. NW TO N WINDS WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT...WITH LINGERING LOW LEVEL MOISTURE. KEPT SLIGHT
CHANCE-CHANCE POPS NEAR LAKE SUPERIOR AS 850MB TEMPS FALL TO AROUND
-2C BY DAYBREAK FRIDAY. HIGHS IN THE 60S...AND EVEN UPPER 50S LOOK
REASONABLE FOR BOTH THURSDAY AND FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 134 PM EDT SUN SEP 8 2013
THE POCKET OF LOW CLOUDS SHOULD FINALLY BE EXITING KCMX AT TAF
ISSUANCE TIME. THE REST OF THE AFTERNOON SHOULD SEE VFR CONDITIONS
WITH HIGH PRESSURE OVERHEAD. HIGH CLOUDS WILL CONTINUE TO STREAM
OVER THE AREA AHEAD OF A LOW PRESSURE SYSTEM IN THE WESTERN PLAINS
STATES. THESE CLOUDS WILL THICKEN AND LOWER TONIGHT AS THE LOW MOVES
INTO THE EASTERN DAKOTAS.
WILL NEED TO WATCH FOR LOWER CLOUDS POSSIBLY MOVING NORTH INTO THE
CWA LATE TONIGHT INTO TOMORROW MORNING. THESE CLOUDS WOULD BE
ASSOCIATED WITH THE STRATUS NOW IN SOUTHWEST WISCONSIN. IF THE
PRECIPITATION NORTHWEST OF MINNEAPOLIS HOLDS TOGETHER AND DROPS
SOUTHEAST INTO NORTHERN/CENTRAL WISCONSIN...THIS WOULD EXPAND THE
ONGOING STRATUS. THEN...WITH 925MB FLOW INCREASING OUT OF THE
SOUTHERLY DIRECTION OVERNIGHT...IT WOULD SHIFT NORTH INTO THE AREA.
THIS IS ALSO AROUND THE TIME DECAYING SHOWERS WOULD BE NEARING FAR
WESTERN UPPER MICHIGAN. WILL ADD SCT WORDING FOR THE CLOUDS AT IWD
DUE TO LOWER CONFIDENCE LATE TONIGHT INTO TOMORROW MORNING AND
UNFAVORABLE SOUTH-SOUTHEAST FLOW. DID OPT FOR A MVFR CLOUD DECK AT
KSAW LATE IN THE MORNING WITH THE WINDS BEING FAVORABLE OUT OF THE
SOUTH-SOUTHEAST.
THE BEST OPPORTUNITY FOR SHOWERS WILL BE AT KCMX/KIWD...WHICH ARE
CLOSEST TO THE BETTER FORCING AS THE WARM FRONT LIFTS THROUGH THE
AREA TOMORROW. CONFIDENCE ON TIMING/LOCATION IS TOO LOW TO HAVE IT
BE THE PREDOMINANT CONDITIONS...SO HAVE JUST MENTIONED VCSH.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 535 AM EDT SUN SEP 8 2013
HIGH PRES OVER NRN ONTARIO WILL DRIFT SE TODAY. JUST AHEAD OF THE
HIGH...EXPECT A BRIEF PUSH OF STRONGER WINDS (GUSTS TO 20-25KT) OVER
MUCH OF LAKE SUPERIOR EARLY THIS MORNING. COASTAL CONVERGENCE OVER
FAR WRN LAKE SUPERIOR AND PERHAPS BTWN THE HURON ISLANDS AND THE
KEWEENAW MAY STILL LEAD TO SOME GUSTS OVER 20KT LOCALLY THRU THE
AFTN. OTHERWISE...WINDS WILL SETTLE DOWN A BIT FOR THE AFTN...
ESPECIALLY OVER THE E...CLOSER TO SFC HIGH PRES CENTER. AS THE HIGH
MOVES AWAY FROM THE UPPER LAKES TONIGHT...GRADIENT SHOULD REMAIN
WEAK ENOUGH TO KEEP WINDS UNDER 20KT.
ANOTHER PERIOD OF STRONGER WINDS WILL BE POSSIBLE THURSDAY INTO
THURSDAY EVENING...WITH N-NW GUSTS OF 25-30KTS OVER MAINLY CENTRAL AND E
LAKE SUPERIOR...AS STRONG HIGH PRESSURE NEARS FROM S CENTRAL
CANADA AND LOW PRESSURE EXITS ACROSS QUEBEC.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...KF
AVIATION...SRF
MARINE...KF
AREA FORECAST DISCUSSION
NWS GAYLORD MI
110 PM EDT SUN SEP 8 2013
.SYNOPSIS...
ISSUED AT 304 AM EDT SUN SEP 8 2013
HIGH PRESSURE PUSHING INTO THE STATE IS BRINGING WITH IT
SIGNIFICANTLY COOLER AND DRIER AIR TODAY. THE WARM AIR WILL
BEGIN TO RETURN MONDAY AS A WARM FRONT MOVES TOWARDS THE REGION.
THIS WILL BRING RENEWED CHANCES FOR SHOWERS AND THUNDERSTORMS.
WARM AND MUGGY CONDITIONS WILL PERSIST INTO TUESDAY BEFORE ANOTHER
COLD FRONT ARRIVES LATE TUESDAY. MUCH COOLER AIR WILL MOVE INTO
NORTHERN MICHIGAN TO END THE WEEK.
&&
.UPDATE...
ISSUED AT 105 PM EDT SUN SEP 8 2013
NO CHANGES TO THE FORECAST...STRATOCUMULUS THAT HAS FORMED THIS
MORNING HAS MIXED OUT AS EXPECTED...WITH JUST SOME HIGH CLOUDS
POURING INTO THE REGION FOR THIS AFTERNOON. TEMPERATURES LOOK TO
REMAIN ON TRACK...WITH LIGHTER EASTERLY FLOW COMPARED TO THIS
MORNING AS THE PRESSURE GRADIENT HAS SLACKENED AND HAS PUSHED TO
THE SOUTH.
UPDATE ISSUED AT 939 AM EDT SUN SEP 8 2013
CHANGES THIS HOUR: PRIMARY CHANGES WILL BE TO CLOUD COVER THROUGH
THE DAY...WITH RECENT OBSERVATIONS AND NEAR TERM RAP BUFR PROGS
SUGGESTING THAT WE/LL BUBBLE UP A BIT OF STCU BEFORE A GRADUAL
CLEARING TREND TAKES PLACE THIS AFTERNOON. OVERALL...THIS RESULTS
IN PRETTY MINOR CHANGES TO THE GOING FORECAST...WITH A PARTLY
SUNNY DAY EXPECTED FOR MOST. TEMPS LOOK ON TRACK TO REACH WITHIN A
FEW DEGREES OF THE 70F MARK.
UPDATE ISSUED AT 645 AM EDT SUN SEP 8 2013
STRONG HIGH PRESSURE...SUBSIDENCE AND DRY AIR THRU THE COLUMN
CONTINUES TO BUILD SOUTHWARD OUT OF ONTARIO AND INTO MICHIGAN
EARLY THIS MORNING. A FEW LOW CLOUDS REMAIN ACROSS FAR SRN
SECTIONS OF OUR CWA...BUT THOSE CLOUDS WILL SLIDE FURTHER SOUTH AS
DRIER AIR CONTINUES TO BUILD SOUTHWARD. ALSO...THE START OF
DAYTIME HEATING WILL LEND TO THE DISSIPATION OF RESIDUAL LOW
CLOUDS THRU DIURNAL MIXING ONCE THE SUN RISES. THE REST OF THE DAY
WILL BE SUNNY BUT NOT AS WARM AND HUMID AS YESTERDAY. HIGH TEMPS
THIS AFTERNOON WILL ONLY WARM INTO THE MID 60S TO LOWER 70S.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 304 AM EDT SUN SEP 8 2013
CURRENTLY, THE 500 MB RIDGE TO THE WEST LOOKS TO BE IN THE
BEGINNING STAGES OF FLATTENING AT THE LEAST AS THE WESTERN CUTOFF
LOW PUSHES INTO THE PAC NORTHWEST. TO THE EAST THE 500 MB TROUGH
LOOKS TO BE HOLDING IN PLACE. THIS SETS UP THE UPPER GREAT LAKES
FOR NORTHWEST FLOW/WARM ADVECTION PATTERN OVER THE NEXT COUPLE OF
DAYS. HOWEVER, IT THE VERY NEAR TERM (TODAY/TONIGHT), HIGH
PRESSURE WILL BE THE DOMINATE FEATURE.
TODAY...THE DRIER AIR, AS NOTED IN PREVIOUS UPDATES, IS MAKING ITS
WAY INTO THE N LOWER NOW, AS EVIDENT ON THE IR IMAGE. THE CLEARING
LINE HAS MADE IT TO ROUGHLY TO A LINE FROM APN TO FKS. THERE WAS A
CONCERN AT THE OUTSET OF THE EVENING FOR FOG, FROM THE RATHER
SOUPY AIR MASS THAT WAS LEFT FROM THE INITIAL SFC TROUGH. HOWEVER,
A SECOND, WEAKER TROUGH, USHERED IN THE DRIER, AND "BREEZIER"
AIR MASS. WITH THE WINDS OVER LAND, FROM THE TIGHTER GRADIENT,
HOLDING AROUND 5 TO 10 KNOTS, THIS HAS KEPT THE FOG FROM FORMING,
AND LEFT LOW CLOUDS BEHIND THE BOUNDARY. NOW THE DRY AIR AT 850 MB
AND BELOW IS PUSHING INTO THE REGION AND CLEARING THE FORECAST
AREA. BY DAYBREAK, IT LOOKS LIKE WE WILL GET MOSTLY SUNNY SKIES,
WITH ONLY THE CIRRUS BLOW OFF FROM THE MCS IN DAKOTAS, WHICH
SHOULD MOVE SOUTHEAST IN THE COMING HOURS, MISSING MICHIGAN.
TONIGHT...THE HIGH WILL TRANSIT THE FORECAST AREA DURING THE DAY,
SO THAT IN THE EVENING, THE RETURN FLOW WILL START IN NW LOWER.
TEMPERATURES THERE SHOULD IN THE 50S, WHILE IN NE LOWER AND E
UPPER THE WINDS WILL DECOUPLE FOR A TIME WHILE THE CORE OF THE
HIGH EXITS AND ALLOW SOME RADIATIONAL COOLING. TEMPERATURES WILL
FALL INTO THE UPPER 40S BEFORE HOLDING FROM THE RETURN FLOW AND
THE INCREASING CLOUDS FROM THE WARM FRONT BEGINNING TO FORM. THE
NAM AND GFS KEEP THE REGION DRY THROUGH 12Z AS THE BETTER
ISENTROPIC FORCING REMAINS UPSTREAM IN THE MINNESOTA ARROWHEAD.
THE ECMWF SEEMS THE OUTLIER WITH THE MOISTURE SOMEWHAT MORE
AGGRESSIVELY MOVING INTO LOWER MICHIGAN BY 12Z. CONSIDERING THAT
ALL THE MODELS HAVE THE SAME BASIC SCENARIO OF THE HIGH MOVING
TOWARD THE SE, AND THAT THE RETURN FLOW FROM A HIGH RETREATING IN
THAT DIRECTION USUALLY TAKES A LITTLE LONGER FOR THE RETURN FLOW
TO PUSH MOISTURE INTO THE STATE, THINK THAT THE GFS/NAM IDEA IS
RIGHT, SO HAVE THE RAIN STAYING OFF TO THE WEST THROUGH 12Z.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 304 AM EDT SUN SEP 8 2013
MONDAY THRU TUESDAY...SURFACE HIGH CENTER WILL SHIFT EAST OF OUR
STATE LATE SUNDAY NIGHT...WITH RETURN MOIST SOUTHERLY FLOW QUICKLY
KICKING IN EARLY MONDAY. A WARM FRONT ASSOCIATED WITH LOW PRESSURE
DEVELOPING IN THE NRN PLAINS WILL LIFT NE INTO NRN MICHIGAN ON
MONDAY. CHANCES OF SHOWERS AND STORMS WILL INCREASE...ESPECIALLY
ACROSS UPR AND FAR NRN LWR MICHIGAN AS DEEP MOISTURE POOLS AROUND
AND NORTH OF THE WARM FRONT. GREATEST CHANCE OF PRECIP WILL DEVELOP
MONDAY NIGHT AS THE SURFACE LOW CENTER TRACKS ALONG THE WARM FRONT
THRU THE STRAITS. THE ASSOCIATED COLD FRONT WILL SLOWLY SLIDE THRU
OUR CWA TUESDAY AND TUESDAY NIGHT. FOCUS OF CONVECTIVE DEVELOPMENT
WILL GENERALLY FOLLOW THIS BOUNDARY... GRADUALLY SHIFTING HIGHEST
POPS FROM ERN UPR AND FAR NRN LWR MICHIGAN ON TUESDAY SOUTHWARD TO
ALL OF NRN LWR MICHIGAN FOR TUESDAY NIGHT. TEMPS WILL RESPOND TO
STRENGTHENING WAA SOUTH OF THE WARM FRONT AND AHEAD OF THE COLD FRONT
BOTH MONDAY AND TUESDAY. HIGH TEMPS MONDAY AFTERNOON WILL WARM WELL
INTO THE 70S ACROSS NRN LWR MICHIGAN SOUTH OF THE WARM FRONT...AND
AROUND 70 ACROSS ERN UPR MICHIGAN WITHIN THICKER CLOUDS AND BETTER
PRECIP CHANCES ALONG THE WARM FRONT. HIGH TEMPS TUESDAY AFTERNOON
WILL VARY GREATLY ACROSS OUR CWA AS THE COOL FRONT SLIDES
THRU...RANGING FROM THE MID TO UPPER 70S IN ERN UPR MICHIGAN TO
AROUND 90 NEAR SAGINAW BAY.
WEDNESDAY THRU SATURDAY...BROAD DEEP CYCLONIC FLOW WILL LINGER ACROSS
THE WRN GREAT LAKES REGION IN THE WAKE OF THE COLD FRONT WEDNESDAY
INTO THURSDAY...AS WILL SOME LIMITED MOISTURE. LOW LEVEL CONVERGENCE
VIA THE CYCLONIC FLOW AND POCKETS OF MOISTURE WILL KEEP SMALL
CHANCES OF SHOWERS IN THE FORECAST THRU THURSDAY. CAA BEHIND THE
FRONT WILL DROP HIGH TEMPS BACK INTO THE 70S ON WEDNESDAY. A
STRONGER COLD FRONT WILL MOVE THRU THE WRN GREAT LAKES ON
THURSDAY...DROPPING TEMPS TO BELOW NORMAL LEVELS FOR THE LAST PART
OF THE WEEK. HIGH TEMPS ON THURSDAY WILL RANGE FROM THE MID 60S IN
ERN UPR MICHIGAN TO THE LOWER 70S IN OUR SE CWA. HIGH TEMPS ON
FRIDAY WILL STRUGGLE TO WARM OUT OF THE 50S ACROSS ERN UPR
MICHIGAN...AND WILL BE MAINLY IN THE LOWER 60S ACROSS NRN LWR
MICHIGAN. LATEST ECMWF IS TRENDING COLDER FOR FRIDAY...DROPPING 850
MB TEMPS TO -2 C ACROSS OUR FAR NRN CWA. COLD CANADIAN SURFACE HIGH
CENTER WILL MOVE OVERHEAD FRIDAY NIGHT/EARLY SATURDAY. THIS COLD
AIRMASS COMBINED WITH CLEARING SKIES AND LIGHT/CALM WINDS WILL
LIKELY RESULT IN SOME PATCHY FROST DEVELOPING LATE FRIDAY NIGHT INTO
EARLY SATURDAY. SATURDAY WILL BE ANOTHER COOL DAY...WITH HIGHS ONLY
IN THE 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 645 AM EDT SUN SEP 8 2013
OVERALL VFR CONDITIONS ARE EXPECTED ACROSS ALL NRN LWR MICHIGAN
TAF SITES THRU EARLY MORNING MORNING AS STRONG COOL CANADIAN HIGH
PRESSURE AND DRY AIR CONTINUE TO BUILD SOUTH INTO MICHIGAN. N/NE
WINDS AOB 10 KTS TODAY WILL BECOME LIGHT AND VARIABLE TONIGHT AS
THE SURFACE HIGH CENTER MOVES OVERHEAD.
&&
.MARINE...
ISSUED AT 304 AM EDT SUN SEP 8 2013
SMALL CRAFT WINDS ARE EXPECTED THROUGH THE MORNING AS THE GRADIENT
WON`T SLACKEN OVER THE LAKES UNTIL THE AFTERNOON. WINDS WILL
CONTINUE TO FALL OFF AS THE HIGH TAKES CONTROL THROUGH TONIGHT.
WINDS AND WAVES WILL INCREASE ON MONDAY AND MONDAY NIGHT AS THE
SFC LOW APPROACHES THE REGION.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LHZ348-
349.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...NS
SYNOPSIS...JL
SHORT TERM...JL
LONG TERM...MR
AVIATION...MR
MARINE...JL
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1236 PM CDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 1236 PM CDT SUN SEP 8 2013
FCST IS EVOLVING FAIRLY CLOSE TO EXPECTATIONS. THIS IS A COMPLEX
SITUATION WITH TSTM OUTFLOW SHIFTING WINDS TO THE NE OVER S-CNTRL
NEB AND MAINTAINING HIGHER DWPTS...AND EVEN ADVECTING THEM BACK
SWD. THIS IS NOT WHAT WAS ANTICIPATED VIA THE MODELS. THE SFC
TROF WAS FCST TO LIFT BACK N AND IT STILL WILL...BUT LATER THAN
PLANNED. THE DECISION TO LOWER HIGHS LOOKS VERY VERY GOOD /SEE
PRVS UPDATE/. MODEST CONVERGENCE WILL BE OVER THE FCST AREA AND
HI-RES MODELS WITH EXPLICIT CONVECTION ARE FCSTG A TSTM OR TWO TO
DEVELOP AFTER 4 PM. SO A LOW 20 PERCENT POP HAS BEEN EXPANDED TO
THE ENTIRE FCST AREA DUE TO INHERENT UNCERTAINTY.
WE ARE CONTEMPLATING A RED FLAG WRNG FOR OUR N-CNTRL KS COUNTIES
TOMORROW AFTN...PENDING REVIEW OF ADDITIONAL 12Z GUIDANCE.
PROBABILITY OF ISSUANCE 80 PERCENT.
UPDATE ISSUED AT 936 AM CDT SUN SEP 8 2013
FCST HAS BEEN UPDATED TO LOWER HIGHS WHERE FOG IS INHIBITING
HEATING /ALONG AND N OF I-80/ AND WHERE THE APPROACHING OUTFLOW
MAY ALSO KEEP TEMPS DOWN. ALSO LOWERED DWPTS PER REASONING FROM
THE PRVS UPDATE. WIND DIRECTION HAS BEEN ADJUSTED THRU MIDDAY TO
ALLOW FOR WIND SHIFT TO NE BEHIND THE BOUNDARY.
UPDATE ISSUED AT 908 AM CDT SUN SEP 8 2013
THE DENSE FOG ADVY HAS BEEN EXTENDED ONE MORE HOUR PER WEBCAMS...
AIRPORT VSBYS AND VIS SATELLITE. USING CONDITIONAL CLIMATOLOGY
/LOOKING BACK AT PAST SIMILAR EVENTS DURING AUG-SEP/ THE
PROBABILITY OF IFR CIG/VSBY CONTS VERY HIGH /81 PERCENT/ THRU 14Z
AND THEN DROPS TO 62 PERCENT 15Z AND 38 PERCENT BY 16Z.
SATELLITE SHOWS A DRY OUTFLOW BOUNDARY FROM OVERNGT TSTMS
APPROACHING NEB HWY 92. THIS WILL SHIFT WINDS TO NE AS ALREADY
SEEN AT ODX/BVN. THIS WILL COMPLICATE THE FCST HIGHS TODAY AND
DEPENDING ON ITS DENSITY IT MAY PREVENT THE E-W TROF FROM LIFTING
BACK N.
MRNG DATA DIAGNOSIS IS STILL ON-GOING...BUT ENVISION DWPTS WILL
NEED TO BE LOWERED SUBSTANTIALLY S AND W OF THE TRI-CITIES. HIGH
TEMPS IN THE 100S VIRTUALLY GUARANTEES MIN RH DROPPING INTO THE
TEENS THIS AFTN.
MORE LATER...
UPDATE ISSUED AT 706 AM CDT SUN SEP 8 2013
WITHIN THE PAST HOUR...DENSE FOG HAS EXPANDED IN COVERAGE EASTWARD
ACROSS MOST COUNTIES MAINLY ALONG/NORTH OF THE INTERSTATE 80
CORRIDOR PER AUTOMATED AIRPORT OBS AND WEBCAMS...WHILE
MAINTAINING INTENSITY FARTHER SOUTHWEST INTO THE HOLDREGE AREA AS
WELL. AS A RESULT...HAVE ADDED SEVERAL MORE COUNTIES TO THE DENSE
FOG ADVISORY...WHICH NOW INCLUDES GENERALLY ALL AREAS NORTH OF AN
ELWOOD-HASTINGS-YORK LINE. THE LATEST HRRR VISIBILITY PRODUCT HAS
CAPTURED THE AREA OF DENSE FOG FAIRLY WELL...AND SUGGESTS MOST OF
IT SHOULD LIFT/IMPROVE CONSIDERABLY BY 9 AM OR SO...BUT COULD
MAYBE LINGER CLOSER TO 10 AM IN THE CORE OF THE FOG AREA. INCOMING
DAY SHIFT WILL MONITOR TRENDS AND ADJUST HEADLINE AS NECESSARY.
UPDATE ISSUED AT 546 AM CDT SUN SEP 8 2013
WENT AHEAD WITH A DENSE FOG ADVISORY FOR A FEW HOURS THIS MORNING
FOR AREAS GENERALLY WEST OF HIGHWAY 281 AND ALONG THE INTERSTATE
80 CORRIDOR WHERE VSBY AVERAGE ONE QUARTER MILE OR LESS. VSBYS
WILL IMPROVE AFTER SUNRISE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 453 AM CDT SUN SEP 8 2013
AN UPPER LEVEL RIDGE OF HIGH PRESSURE CONTINUES TO DOMINATE THE
WEATHER PATTERN ACROSS THE INTERIOR CONUS...RESULTING IN HOT
TEMPERATURES FOR EARLY SEPTEMBER...WELL ABOVE NORMAL. AT THE
SURFACE...LOW PRESSURE WAS CENTERED ALONG THE WY/NEB BORDER...WITH
A STALLED FRONTAL BOUNDARY EXTENDING EASTWARD ALONG THE NEB/KS
STATELINE. HIGH DPS IN THE UPPER 60S TO AROUND 70 HAVE POOLED NORTH
OF THE BOUNDARY AND IN PRESENCE OF THE LLVL MOISTURE...SOME PATCHY
FOG HAS DEVELOPED WITH THE LOWEST VSBYS SO FAR AROUND ONE OR TWO
MILES. WILL CONTINUE TO MONITOR VSBY TRENDS THRU THE PRE DAWN
HOURS AS MODELS ARE NOT IN AGREEMENT ON HOW SIGNIFICANT FOG WILL BE
...AND THE HRRR SUGGESTS POTENTIAL FOR DENSE FOG.
THE FRONTAL BOUNDARY ALONG THE NEB/KS STATELINE WILL LIFT NORTH AS A
WARM FRONT TODAY AND TEMPERATURES WILL BE TOASTY WITH READINGS
RISING WELL INTO THE 90S...AND OUR WESTERN/SOUTHERN ZONES WILL BE
EVEN WARMER WITH HIGHS IN THE 100 TO 105F RANGE. HEAT INDICES WILL
BE FAIRLY CLOSE OR JUST BELOW AMBIENT TEMPS AS DPS LOWER BEHIND
BOUNDARY...AND SHOULD REMAIN SHY OF HEAT ADVISORY CRITERIA.
CANNOT COMPLETELY RULE OUT THE POTENTIAL FOR AN ISOLATED
THUNDERSTORM THIS AFTERNOON/EVENING...GENERALLY NORTH OF INTERSTATE
80 AS THE WARM FRONTAL BOUNDARY LIFTS ACROSS. MODELS INDICATE
PRESENCE OF MID LEVEL WAA AND FRONTOGENESIS BETWEEN H85 AND H7 NORTH
OF I-80 AND DAYTIME HIGHS ARE RIGHT AROUND CONVECTIVE TEMPERATURES.
BOTH THE NAM/GFS INDICATE THE LIFT/FORCING...BUT ONLY THE 4KM SPC
WRF INDICATES DEVELOPMENT. THE CONVECTIVE POTENTIAL IS LIMITED WITH
CAPPING/WARM MID LEVEL TEMPS...BUT CANNOT RULE OUT AN ISOLATED CHC
AND HAVE ADDED SMALL POPS.
DRY AND MILD CONDITIONS ARE FORECAST LATE EVENING ON...WITH LOWS
AVERAGING IN THE UPPER 60S TO AROUND 70F.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 453 AM CDT SUN SEP 8 2013
THERE CONTINUES TO REMAIN A FAIRLY CONSISTENT FORECAST THEME
THROUGH THESE 6 DAYS...WITH MONDAY FEATURING THE FINALE OF A
MEMORABLE EARLY SEPTEMBER HOT SPELL...ALTHOUGH TUESDAY STILL LOOKS
PLENTY TOASTY AS WELL ACROSS ROUGHLY THE SOUTHEASTERN 1/3 OF THE
CWA WITH HIGHS BETWEEN 90-95. THEREAFTER...THE WED-SAT TIME FRAME
IS EXPECTED TO FEATURE HIGHS PREDOMINANTLY IN THE 80S...WHICH ON
SEVERAL DAYS WILL STILL BE A FEW DEGREES ABOVE NORMAL DESPITE
BEING MORE SEASONABLE. AS FOR SHOWER/THUNDERSTORM CHANCES...THERE
REMAINS AT LEAST A SLIGHT CHANCE MENTION IN THE FORECAST FOR AT
LEAST A PORTION OF THE OUTLOOK AREA DURING EVERY PERIOD FROM
MONDAY NIGHT THROUGH FRIDAY NIGHT...WITH SATURDAY VOID OF
MENTIONABLE POPS...AT LEAST FOR NOW. IF ANYTHING...UNCERTAINTY
CONTINUES TO GROW REGARDING WHICH OF THESE PERIODS MIGHT BE
FAVORED FOR MORE WIDESPREAD PRECIPITATION COVERAGE...SO FOR NOW
MOST OF THESE CHANCES CONTINUE TO BE HELD DOWN IN THE 20-30
PERCENT RANGE. AS DISCUSSED OVER THE PAST 24 HOURS...MONDAY COULD
POTENTIALLY FEATURE SOME OF THE HIGHEST FIRE DANGER THE LOCAL AREA
HAS SEEN THIS SUMMER...AND THESE CONCERNS ARE OUTLINED IN GREATER
DETAIL IN THE SEPARATE FIRE WEATHER SECTION BELOW.
STARTING WITH MONDAY/MONDAY NIGHT...THE LATEST 00Z/06Z MODELS ARE
IN GOOD AGREEMENT ON THE BIG PICTURE ALOFT...WITH THE LOCAL AREA
EXPERIENCING SOUTHWESTERLY FLOW ALOFT AS THE CENTER OF THE
EXPANSIVE RIDGE AXIS CURRENTLY PARKED OVERHEAD CONTINUES TO DRIFT
FARTHER AWAY INTO THE SOUTHEAST STATES...AS A PROGRESSIVE
SHORTWAVE TROUGH TRANSLATES ALONG THE U.S./CANADA BORDER FROM A
CENTRAL POSITION OVER NORTHERN MT AT SUNRISE MONDAY...TO NORTHERN
MN BY SUNRISE TUESDAY. IN RESPONSE...A MODEST COLD FRONT WILL
DRIFT SOUTHEASTWARD INTO THE CENTRAL PLAINS. DURING THE DAYTIME
MONDAY...THE CWA WILL REMAIN JUST AHEAD OF THIS COLD FRONT...WHICH
IS FORECAST TO ALIGN FROM NORTHEAST TO TO NORTH CENTRAL NEB BY
LATE AFTERNOON...BEFORE SLOWLY INFILTRATING MUCH OF THE
NORTHERN/CENTRAL CWA MONDAY NIGHT. THE DAYTIME HOURS SHOULD BE
ANOTHER HOT ONE AREA-WIDE...AS SUSTAINED SOUTH-SOUTHWEST WINDS
PICK UP TO AT LEAST 15-20 MPH WITH GUSTS 25+ MPH IN MOST
AREAS...EXCEPT FOR A BIT LIGHTER SPEEDS POSSIBLE IN FAR NORTHWEST
COUNTIES IN CLOSET PROXIMITY TO THE APPROACHING TROUGH AXIS. WITH
DEEP MIXING FORECAST TO AVERAGE UP TO AROUND 750 MILLIBARS OVER
MUCH OF THE CWA...ANTICIPATE DEWPOINTS TO FALL WELL DOWN INTO THE
50S DURING THE AFTERNOON...WITH 40S IN SEVERAL SOUTHWESTERN
COUNTIES. IN THEORY...THIS SETUP SHOULD SET THE STAGE FOR SOME OF
THE HOTTEST READINGS OF THIS ENTIRE HOT STRETCH...ESPECIALLY IN
CENTRAL/NORTHEAST COUNTIES...BUT SOMEWHAT ODDLY MET/MAV GUIDANCE
SUGGESTS HIGHS MONDAY WOULD BE A TOUCH COOLER THAN THOSE TODAY.
DESPITE THIS...HAVE KEPT FORECAST HIGHS AT LEAST A FEW DEGREES
ABOVE A GUIDANCE BLEND IN MOST AREAS...WITH ALL BUT THE FAR
NORTHERN CWA AIMED TO TOP OUT SOMEWHERE IN THE 98-103 RANGE...WITH
THE HIGHER END OF THIS RANGE IN FAR SOUTHERN/SOUTHWEST COUNTIES.
DUE TO THE LOWER DEWPOINTS...HEAT INDEX VALUES IN MOST AREAS ONLY
AVERAGE 95-100 DEGREES. AS FOR STORM CHANCES...MODELS VARY ON HOW
AGGRESSIVELY CONVECTION MAY TRY TO SLIP INTO OUR FAR NORTHWEST
ZONES MONDAY EVENING/NIGHT...WITH SOME BRINGING THEM JUST IN WHILE
OTHERS KEEP THEM JUST OUTSIDE. GIVEN THE SLOWING NATURE OF THE
SURFACE FRONT...HAVE BACKED OFF MON NIGHT POPS TO ONLY ABOUT THE
NORTHWESTERN 1/4 OF THE CWA...WHILE THE VAST MAJORITY OF THE CWA
STAYS DRY. ALTHOUGH ANY MARGINAL SEVERE THREAT DURING THE LATE
AFTERNOON/EVENING SHOULD LARGELY TARGET THE SANDHILLS REGION JUST
TO OUR NORTHWEST...SUPPOSE A STRONG TO MARGINALLY SEVERE STORM OR
TWO CANNOT BE RULED OUT SLIPPING INTO OUR AREA...WITH THE MAIN
THREAT BEING GUSTY WINDS DUE TO HIGH CLOUD BASES IN THE DEEPLY-
MIXED AIRMASS NEAR THE FRONT. SEVERE PARAMETERS ARE NOT ALL THAT
IMPRESSIVE...WITH THE GFS SUGGESTING EARLY EVENING CAPE AVERAGING
WELL UNDER 1000 J/KG...ALTHOUGH DEEP LAYER SHEAR ISN/T ALL THAT
POOR AROUND 30-40 KNOTS.
TUESDAY/TUES NIGHT...THE NORTHERN MN SHORTWAVE TROUGH QUICKLY
SLIDES EAST INTO SOUTHEAST CANADA...AND ALTHOUGH THE CWA SEES A
PERIOD OF DECENT UPPER JET ENTRANCE REGION LIFT AND ASSOCIATED MID
LEVEL FRONTOGENESIS...THE MAIN FORCING STEADILY SLIDES AWAY TO THE
NORTHEAST...ALLOWING THE SURFACE FRONT TO LOSE STEAM AND GENERALLY
STALL OUT WITHIN OR NEAR THE SOUTHERN EDGE OF THE CWA BY TUESDAY
AFTERNOON/NIGHT. THERE COULD BE A DECENT TEMP GRADIENT IN HIGHS
TUESDAY AFTERNOON...AND HAVE MADE LITTLE CHANGE...STILL AIMING FOR
LOW-MID 80S NORTHWEST TO LOW-MID 90S SOUTHEAST. IF ENOUGH
INSTABILITY BUILDS ALONG THE SURFACE BOUNDARY...COULD MAYBE SEE
SOME STRONG TO SEVERE NEAR-SURFACE BASED STORMS FLARE UP IN
SOUTHERN COUNTIES TUESDAY AFTERNOON/EVENING...WITH MORE ELEVATED
ACTIVITY DEVELOPING FARTHER NORTH AS THE NIGHT WEARS ON IN RESPONSE
TO MID-LEVEL THETA-E ADVECTION. EVEN ONLY 3 DAYS
AWAY...UNCERTAINTY IS VERY HIGH HERE...AND HAVE KEPT DAYTIME POPS
IN SLIGHT CHANCE RANGE...WITH A GREATER COVERAGE OF 30 POPS
TUESDAY NIGHT.
WEDNESDAY THROUGH FRIDAY NIGHT...THERE CONTINUES MULTIPLE...MAINLY
20-30 PERCENT POPS ACROSS ALL/MOST OF THE CWA...AND OBVIOUSLY A
LOT OF FINE-TUNING WILL NEED DONE HERE IN THE COMING DAYS. ON THE
LARGE SCALE ALOFT...THE LOCAL AREA SETS UP UNDER FAIRLY WEAK WEST-
SOUTHWEST FLOW ALOFT...IN THE WAKE OF A DEEPENING TROUGH MIGRATING
ACROSS SOUTHEAST CANADA/THE NORTHEAST CONUS...AND ALONG THE
NORTHERN PERIPHERY OF AN EXPANSIVE SOUTHERN CONUS RIDGE
AXIS...WHICH INSTEAD OF BEING OVERHEAD AS THE CURRENT ONE
IS...THIS TIME SETS UP FARTHER SOUTH MORE OVER OK/TX. WITH THE
REMNANT...GENERALLY EAST-WEST SURFACE FRONT REMAINING IN PLACE
NEAR OR OVER THE CWA DURING THE TIME...AND WITH THE AREA BEING
PRONE TO MAINLY NOCTURNAL INCREASES IN THETA-E ADVECTION IN THE
850-700MB LAYER...THERE COULD BE SEVERAL ROUNDS OF
SHOWERS/STORMS...AND MAYBE EVEN AN OCCASIONAL SEVERE THREAT. TEMP-
WISE...LITTLE CHANGE FROM PREVIOUS WITH HIGHS GENERALLY LOW-MID
80S MOST AREAS...ALTHOUGH SOME 70S NOT OUT OF THE QUESTION.
SATURDAY...HAVE LEFT OUT POPS FOR NOW DUE TO INCREASING MODEL
VARIABILITY AND UNCERTAINTY AT THIS TIME RANGE..BUT DRY IS NO
GUARANTEE...WITH THE LOCAL AREA REMAINING NORTH OF THE SOUTHERN
PLAINS RIDGE AND POSSIBLY IN THE PATH OF SOME LOW AMPLITUDE
DISTURBANCES BRUSHING BY THROUGH THE NORTHERN PLAINS. WILL CALL
FOR MAINLY MID 80S IN NEB ZONES AND UPPER 80S IN KS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1236 PM CDT SUN SEP 8 2013
THIS AFTN: VFR SKC...BUT A FEW CU MAY DEVELOP AROUND 9K FT. ONE OR
TWO COULD DEVELOP INTO A CB/TSTM. WILL MONITOR THRU THE AFTN.
WHILE WINDS ARE CURRENTLY LGT FROM THE N...EXPECT A SHIFT TO SE
SOMETIME THIS AFTN.
TNGT: A VERY LOW PROBABILITY FOR A VCTS THRU 02Z. THEN VFR SKC. S
WINDS WILL AVERAGE 10 KTS. CURRENTLY WE DO NOT EXPECT FOG TO
REDEVELOP. AS WINDS FRESHEN FROM THE S...THIS SHOULD ADVECT DRIER
AIR IN FROM THE S.
MON THRU 18Z: VFR SKC. SSW WINDS BECOME GUSTY 15Z-16Z WITH GUSTS
UP TO 26 KTS.
CIG CONFIDENCE: HIGH
VSBY CONFIDENCE: MEDIUM
WIND CONFIDENCE: MEDIUM
WX CONFIDENCE: MEDIUM
&&
.FIRE WEATHER...
ISSUED AT 453 AM CDT SUN SEP 8 2013
AS PREVIOUSLY DISCUSSED OVER THE PAST 24 HOURS...MONDAY CONTINUES
TO APPEAR A DECENT CANDIDATE FOR NEAR-CRITICAL TO POTENTIALLY
CRITICAL FIRE DANGER ACROSS PARTS OF THE CWA. ON SATURDAY...AREA
FIRE WEATHER MANAGERS DEEMED VEGETATIVE FUELS ACROSS OUR KS ZONES
TO BE DRY ENOUGH TO SUPPORT POSSIBLE HEADLINES...ALTHOUGH FUELS
ACROSS OUR NEBRASKA COUNTIES ARE STILL ASSUMED TO BE GREEN ENOUGH
TO PRECLUDE MAJOR ISSUES BARRING FURTHER INFORMATION. AS LONG AS
FUELS ARE DEEMED FAVORABLE...CRITICAL FIRE WEATHER THRESHOLDS
ACROSS THE GID CWA INCLUDE A COMBINATION OF RELATIVE HUMIDITY
AT/BELOW 20 PERCENT AND SUSTAINED WINDS/GUSTS OF 20 MPH/25 MPH FOR
3+ HOURS. AS THE FORECAST CURRENTLY STANDS...A DECENT OVERLAP OF
THESE WIND/RH PARAMETERS IS ANTICIPATED ACROSS MUCH OF THE
SOUTHWESTERN HALF OF THE CWA MONDAY AFTERNOON...AS INCREASING
SOUTHWESTERLY WINDS ALLOW HOT...DRY AIR TO OVERSPREAD THE AREA.
EVEN IN NORTHEAST PORTIONS OF THE CWA...RH VALUES ARE FORECAST TO
DROP BETWEEN 21-30 PERCENT...SO THERE COULD BE AT LEAST SOME
DEGREE OF FIRE DANGER THERE AS WELL DESPITE THE OVERALL GREENER
FUELS. GIVEN THAT MONDAY AFTERNOON IS STILL 30+ HOURS AWAY AND
STILL SUBJECT TO SOME FINE-TUNING...AND AFTER COORDINATION WITH
SURROUNDING OFFICES...WILL HOLD OFF ON ANY FIRE WEATHER HEADLINES
FOR KS ZONES AT THIS TIME...BUT WILL CONTINUE TO ADVERTISE NEAR-
CRITICAL TO POTENTIALLY CRITICAL CONDITIONS IN THE HAZARDOUS
WEATHER OUTLOOK.
&&
.CLIMATE...
ISSUED AT 453 AM CDT SUN SEP 8 2013
ALTHOUGH CURRENT FORECAST HIGH TEMPERATURES TODAY/MONDAY AT OUR
PRIMARY CLIMATE RECORD SITES GRAND ISLAND/HASTINGS ARE CURRENTLY
FORECAST SLIGHTLY SHY OF RECORDS...IT COULD BE A PRETTY CLOSE
CALL. THOSE RECORDS ARE AS FOLLOWS...
SUNDAY SEP. 8...GRAND ISLAND 101 IN 1931 AND 1928
HASTINGS 101 IN 1931
MONDAY SEP. 9...GRAND ISLAND 104 IN 1931
HASTINGS 102 IN 1919
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...FAY
LONG TERM...PFANNKUCH
AVIATION...HALBLAUB
FIRE WEATHER...PFANNKUCH
CLIMATE...PFANNKUCH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
205 PM EDT SUN SEP 8 2013
.SYNOPSIS...
A MOSTLY DRY COLD FRONT...APPROACHING FROM THE NORTH...WEAKENS AS IT
SLOWLY MOVES THROUGH THE REGION TONIGHT AND MONDAY. WEAK HIGH
PRESSURE BUILDS IN BEHIND THE FRONT. ANOTHER COLD FRONT MOVES
THROUGH THE AREA LATE IN THE WORK WEEK.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
AS OF 1045 AM SUNDAY...
REST OF TODAY: THE MOST STRIKING CHANGE TO THE FORECAST WILL BE AN
INCREASE IN THE AMOUNT OF SUNSHINE... PARTICULARLY OUTSIDE OF THE
TRIAD REGION. LATEST SURFACE MAP SHOWS A WEAK PRESSURE/WIND PATTERN
OVER THE REGION... FEATURING A SURFACE TROUGH THROUGH THE PIEDMONT
AND YESTERDAY`S HIGH PRESSURE AREA SLIDING FURTHER TO OUR SW. THE
SURFACE COLD FRONT NOW STRETCHING FROM AROUND BOSTON TO JUST NORTH
OF THE OH RIVER... MAKING GOOD SOUTHWARD PROGRESS AS IT IS PUSHED BY
COOL DENSE HIGH PRESSURE TO THE NORTH. WIDESPREAD MID CLOUDS TO OUR
NORTH EARLIER THIS MORNING... ACROSS WV/VA/MD/DE/NJ/PA SHORTLY
BEFORE DAYBREAK... HAVE ALMOST COMPLETELY VANISHED AS THEY
ENCOUNTERED THE DRY/STABLE AIR AND DIFFLUENT FLOW OVER NC. RAP MODEL
SOUNDINGS SHOW A FEW MID CLOUDS DRIFTING OVER THE FORECAST AREA THIS
AFTERNOON... BUT THIS APPEARS TO BE SHORT-LIVED WITH MAINLY
SCATTERED CLOUDS... AND MOST OF THE AREA SHOULD SEE MOSTLY SUNNY
SKIES FOR THE MAJORITY OF THE DAY. THE EXCEPTION WILL BE IN THE NW
CWA WHERE MODELS... UPSTREAM SOUNDINGS... AND SATELLITE TRENDS
SUGGEST THAT THE COVERAGE OF MID CLOUDS WILL BE A LITTLE BETTER...
LEADING TO PARTLY CLOUDY SKIES. SEVERAL CONVECTION-ALLOWING MODELS
DEPICT A FEW SPRINKLES MAKING IT INTO THE FOOTHILLS LATE THIS
AFTERNOON... BUT BASED ON THE GENERALLY DOWNSLOPE FLOW AND LACK OF
LOW LEVEL MOISTURE... BELIEVE THESE WILL HOLD JUST NW OF THE CWA.
THICKNESSES AND STATISTICAL GUIDANCE SUPPORT FORECAST HIGHS OF
86-91. -GIH
TONIGHT AND MONDAY:
THE AFOREMENTIONED COLD FRONT WILL PROGRESS SOUTHWARD INTO CENTRAL
NC TONIGHT WILL LITTLE FANFARE... OTHER THAN AN INCREASE IN CLOUD
COVER. THE FRONT IS EXPECTED TO WEAKEN AS IT MOVES THROUGH THE AREA
TONIGHT... BEFORE IT STALLS/DISSIPATES NEAR THE NC/SC BORDER ON
MONDAY. SURFACE HIGH PRESSURE WILL BUILD INTO THE AREA BEHIND THE
FRONT. HOWEVER... AS THE SURFACE HIGH CENTERED OVER THE NORTHERN
MID-ATLANTIC/NORTHEASTERN U.S. MONDAY MORNING SHIFTS EASTWARD AND
OFFSHORE ON MONDAY AFTERNOON... A LIGHT EASTERLY LOW LEVEL FLOW WILL
DEVELOP ACROSS CENTRAL NC. THIS WILL ALLOW LOW LEVEL MOISTURE TO
INCREASE... ALONG WITH POSSIBLY A FEW SHOWERS ACROSS OUR COASTAL
PLAIN COUNTIES IN THE AFTERNOON. HOWEVER... GIVEN INSTABILITY WILL
REMAIN WEAK STILL... WHILE MID LEVEL TEMPS ACTUALLY INCREASE A BIT
AS THE AFOREMENTIONED MID LEVEL RIDGES BEGINS TO BUILD EASTWARD AND
EXTENDS INTO OUR AREA... WILL ONLY KEEP A SLIGHT CHANCE OF SHOWERS
IN THE FORECAST ALONG AND TO THE EAST OF THE I-95 CORRIDOR.
LOW TEMPS MONDAY MORNING ARE EXPECTED TO BE IN THE MID TO UPPER
60S... THANKS TO THE INCREASE IN CLOUD COVER. HIGH TEMPS ON MONDAY
WILL BE TEMPERED BACK A BIT WITH THE EASTERLY LOW LEVEL FLOW. THIS
YIELDS HIGH TEMPS IN THE MID TO UPPER 80S.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 205 PM SUNDAY...
UPPER LEVEL RIDGING WILL EXPAND OVER THE SOUTHEAST US
TUESDAY...WHILE A WEAK SURFACE RIDGE EXTENDS ACROSS THE AREA FROM
THE NORTHEAST. WARMING MID-LEVELS AND LARGE SCALE SUBSIDENCE..ALONG
WITH WEAK INSTABILITY...WILL LIMIT CONVECTIVE POTENTIAL AND TUESDAY
SHOULD BE ANOTHER DRY DAY. THE UPPER RIDGE WILL BEGIN TO WEAKEN
WEDNESDAY AS HEIGHTS BEGIN TO FALL OVER THE GREAT LAKES REGION AND A
LINGERING SHEAR AXIS OFF THE SOUTHEAST US COAST DRIFTS NORTHWARD.
AS SUCH...CONVECTION SHOULD BE LESS INHIBITED OVER THE
MOUNTAINS...LEAVING A SLIGHT CHANCE OF A SHOWER DRIFTING INTO THE
NORTHWEST PIEDMONT. LOW LEVEL THICKNESSES AROUND 1405M
TUESDAY/WEDNESDAY MORNING AND 850MB TEMPS APPROACHING 17-18C SUPPORT
HIGHS IN THE 87-90 RANGE EACH DAY.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 205 PM SUNDAY...
THURSDAY...
HEIGHTS ALOFT WILL LOWER FURTHER ON THURSDAY AS A COLD FRONT MOVES
THROUGH THE MIDWEST STATES. MEANWHILE...MODELS CONTINUE TO SHOW THE
SHEAR AXIS OFF THE SOUTHEAST US COAST DRIFTING BACK TOWARD THE SC
COAST BEFORE BECOMING ABSORBED BY THE LARGER SCALE TROUGH. AT THIS
TIME...NEITHER THE GFS OR ECWMF SHOW MUCH IMPACT OVER EASTERN
NC...KEEPING AN AXIS OF 2 INCH PLUS PW OFFSHORE.
INSTEAD...CONVECTION SHOULD BE FOCUSED OVER WESTERN NC WHERE
SCATTERED SHOWERS AND STORMS SHOULD BE ABLE TO PROGRESS EAST WITH A
STRONGER LEE TROUGH AND WESTERLY STEERING FLOW. WILL INDICATE A
CHANCE INT HE FAR NORTHWEST PIEDMONT AND SLIGHT CHANCE EAST TOWARD
THE TRIANGLE. HIGHS IN THE UPPER 80S TO AROUND 90 ONCE AGAIN.
THURSDAY NIGHT THROUGH SUNDAY...
MEDIUM RANGE MODELS SHOW BETTER LARGE SCALE CONSISTENCY AND
AGREEMENT ON THE COLD FRONT OVER THE MIDWEST MOVING THROUGH CENTRAL
NC THURSDAY NIGHT AND FRIDAY. THE FRONT WILL BRING A LITTLE
MOISTURE WITH IT...WITH UPSTREAM PW OVER 1.75 INCHES...BUT WESTERLY
FLOW AHEAD OF THE FRONT WILL LIMIT ADDITIONAL MOISTURE TRANSPORT. WE
EXPECT JUST SCATTERED SHOWERS THURSDAY NIGHT AND EARLY FRIDAY...WITH
A FEW ISOLATED STORMS POSSIBLE ACROSS THE SOUTH ON FRIDAY BASED ON
THE SLIGHTLY SLOWER ECMWF FRONTAL PASSAGE.
BY SATURDAY...A MODERATELY STRONG CANADIAN HIGH IS FORECAST TO BUILD
ACROSS THE GREAT LAKES TOWARD THE MID-ATLANTIC STATES. LOW-LEVEL
THICKNESSES ARE FORECAST TO DROP RATHER DRAMATICALLY BEHIND THE
FRONT...WITH 1365-1375M POSSIBLE BY SATURDAY/SUNDAY MORNING. THESE
VALUES WOULD SUPPORT BELOW NORMAL TEMPS...WITH HIGHS IN THE MID TO
UPPER 70S AND LOWS IN THE LOW TO MID 50S.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 110 PM SUNDAY...
VFR CONDITIONS WILL DOMINATE INTO MONDAY AFTERNOON. HIGH PRESSURE
OVER THE REGION WILL PUSH FARTHER TO OUR SOUTHWEST WHILE A SURFACE
TROUGH SITS OVER CENTRAL NC. A MOSTLY DRY COLD FRONT LOCATED ACROSS
SRN IN/SRN OH ACROSS MD WILL PUSH STEADILY SOUTHWARD THROUGH
TONIGHT... DROPPING THROUGH NC LATE TONIGHT. ONLY SCATTERED TO
BROKEN VFR CLOUDS BASED ABOVE 5 KFT AGL ARE EXPECTED AHEAD OF AND
JUST BEHIND THIS FRONT LATE TONIGHT INTO EARLY MONDAY MORNING. LIGHT
AND VARIABLE WINDS WILL SWING AROUND TO NORTHEASTERLY BETWEEN 07Z
THROUGH 12Z NORTH-TO-SOUTH AND SPEEDS WILL PICK UP TO 7-10 KTS JUST
BEHIND THE FRONT... WITH A FEW GUSTS FROM THE NE TO 12-14 KTS
POSSIBLE. THERE IS A SMALL CHANCE OF MVFR FOG LASTING FOR JUST AN
HOUR OR SO JUST AHEAD OF THE FRONT LATE TONIGHT... 06Z-12Z.
LOOKING BEYOND 18Z MONDAY... HIGH CONFIDENCE IN VFR CONDITIONS
THROUGH THURSDAY NIGHT... AS WEAK HIGH PRESSURE WILL STRETCH ACROSS
THE AREA THROUGH MID WEEK. PATCHY BRIEF MVFR FOG IS POSSIBLE WITHIN
AN HOUR OF DAYBREAK EACH MORNING TUESDAY THROUGH THURSDAY. ANOTHER
COLD FRONT WILL APPROACH FROM THE NW LATE FRIDAY... AND MAY BRING A
FEW SHOWERS AND STORMS FRIDAY AFTERNOON. -GIH
24 HOUR TAF PERIOD:
VFR CONDITIONS ARE GENERALLY EXPECTED TO PREVAIL ACROSS THE AREA AS
DRY COLD FRONT APPROACHES THE REGION FROM THE NORTH TODAY. THE COLD
FRONT IS EXPECTED TO SLOWLY CROSS CENTRAL NC TONIGHT. IF ANY MVFR
FOG DEVELOPS THIS MORNING AT KRWI IT WILL MIX OUT QUICKLY WITH
DIURNAL MIXING AND SHOULD BE GONE BY 12Z AT THE LATEST. OTHERWISE...
WE WILL SEE MID AND HIGH LEVEL CLOUD COVER ON THE INCREASE THIS
MORNING AS A WEAK DISTURBANCE ALOFT MOVES ACROSS THE AREA. THE
AFOREMENTIONED SURFACE FRONT IS NOT EXPECTED TO MOVE INTO THE AREA
UNTIL LATE TONIGHT. HOWEVER... OUTSIDE OF AN INCREASE IN VFR
CLOUDS... THE FRONT WILL COME THROUGH WITH LITTLE FANFARE AND STALL
NEAR THE NC/SC BORDER AROUND 12Z MONDAY.
OUTLOOK:
PRE-DAWN/MORNING SUB-VFR CONDITIONS WILL BE POSSIBLE EACH MORNING...
ALTHOUGH CONFIDENCE IS VERY LOW FOR ANY WIDESPREAD SUB-VFR
CONDITIONS. OTHERWISE... VFR CONDITIONS ARE EXPECTED... WITH
GENERALLY DRY CONDITIONS (VERY SMALL CHANCE OF A AFTERNOON/EVENING
SHOWER OR STORM EACH DAY AS WELL... BEST CHANCE ON WEDNESDAY AND
THURSDAY AT KGSO/KINT).
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DJF
NEAR TERM...HARTFIELD/BSD
SHORT TERM...SMITH
LONG TERM...SMITH
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
116 PM CDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 116 PM CDT SUN SEP 8 2013
MAIN FORECAST UPDATE WAS TO ADJUST POPS THIS AFTERNOON. AN UPPER
IMPULSE MOVING FROM NORTHEAST MONTANA INTO SASKATCHEWAN IS
PRODUCING SCATTERED SHOWERS AND THUNDERSTORMS OVER NORTHWEST TO
NORTH CENTRAL NORTH DAKOTA INTO EAST CENTRAL MONTANA. THE AREA OF
SHOWERS OVER THE SOUTH CENTRAL HAS MOVED INTO THE JAMES RIVER
BASIN AND DISSIPATED. THUS LOWERED POPS TO CHANCE CATEGORY EXCEPT
FOR THE NORTHWEST-NORTH CENTRAL. THE 12Z WRF...15Z HRRR MESOSCALE
MODELS AS WELL AS THE NAM/GFS INDICATE BEST CHANCES OF CONVECTION
WILL HOLD OFF UNTIL TONIGHT...BUT DID BRING SOME INCREASING
CHANCES INTO THE SOUTHWEST LATER THIS AFTERNOON. ALSO LOWERED
CLOUD COVER ACROSS THE SOUTHWEST AND SOUTH CENTRAL EARLY THIS
AFTERNOON.
UPDATE ISSUED AT 1013 AM CDT SUN SEP 8 2013
QUITE A FEW CHANGES TO THE MORNING UPDATE...MAINLY CENTERED AROUND
CURRENT SHOWER ACTIVITY AND ANTICIPATED DEVELOPMENT OVER THE NEXT
FEW HOURS. CURRENTLY...SHOWERS OVER SOUTH CENTRAL NORTH DAKOTA
CONTINUE TO TRANSLATE EAST. OF THE SHORT TERM MODELS...THE 12 UTC
HRRR SEEMED TO HAVE THE BEST HANDLE ON THE CURRENT SHOWERS. THUS
UTILIZED THE HRRR FOR POP/QPF FORECAST THROUGH THE EARLY
AFTERNOON. THIS RESULTED IN LOWERING OF POPS ACROSS THE NORTH
WHERE LITTLE IS GOING ON...AND INCREASING POPS OVER THE SOUTH
CENTRAL. ALSO LOWERED QPF AMOUNTS THROUGH MUCH OF THE DAY AS RAIN
AMOUNTS HAVE BEEN LIGHT IN THIS AREA OF HIGH BASED SHOWERS. DO NOT
EXPECT HIGHER QPF AMOUNTS UNTIL WE GET SOME CONVECTIVE ELEMENTS
INVOLVED. WITH THE EXTENSIVE CLOUD COVER...ALSO LOWERED
TEMPERATURES A FEW DEGREES MOST AREAS. THINK THE BETTER
PRECIPITATION CHANCES WILL ARRIVE TONIGHT BUT DID BEGIN TO
INCREASE POPS ACROSS THE WEST LATER THIS AFTERNOON.
UPDATE ISSUED AT 638 AM CDT SUN SEP 8 2013
COPIOUS AMOUNTS OF MOISTURE CONTINUE TO OVERSPREAD WESTERN AND
CENTRAL NORTH DAKOTA THIS MORNING AHEAD OF AN APPROACHING
SHORTWAVE. THE LATEST RAP PROGS PWATS GREATER THAN 1.5 INCHES OVER
AREAS SOUTH OF I-94 THIS MORNING. THIS IS ABOUT 200 PERCENT OF
NORMAL FOR SEPTEMBER. GIVEN THE SATURATED ENVIRONMENT...THINK
THE CURRENT FLASH FLOOD WATCH LOOKS GOOD FOR TODAY AND TONIGHT.
NO MAJOR UPDATES WERE REQUIRED FOR THIS UPDATE. ONLY MODIFIED THE
HOURLY TEMP/DEWPOINT/WIND GRIDS BASED ON CURRENT OBS/TRENDS. THE
UPDATED PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 415 AM CDT SUN SEP 8 2013
FORECAST CHALLENGES/HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE
THE COVERAGE AND AMOUNT OF PRECIPITATION NOW THROUGH TONIGHT
ALONG WITH ANOTHER ROUND OF SEVERE WEATHER.
CURRENTLY...UPPER LEVEL RIDGE AXIS CENTERED ACROSS THE DAKOTAS
THIS MORNING. CONVECTION CONTINUES TO BE VIGOROUS FROM ACROSS
SOUTHWEST AND SOUTH CENTRAL NORTH DAKOTA...INTO SOUTH DAKOTA AND
WEST ACROSS SOUTHEAST MONTANA ALONG AN INSTABILITY AXIS AND IN THE
VICINITY OF A LOW LEVEL JET. AT THIS TIME STORMS ARE NON-
SEVERE...DUE IN PART TO RELATIVELY WEAK MID LEVEL LAPSE RATES.
ADDITIONAL SHOWERS/T-STORMS DEVELOPING OVER NORTHEAST MONTANA AND
EAST OVER NORTH CENTRAL AND NORTHEASTERN NORTH DAKOTA.
EXPECT THE CONVECTION OVER MONTANA TO SHIFT NORTH AND EAST INTO
WESTERN AND PORTIONS OF CENTRAL NORTH DAKOTA THIS MORNING AS A
POTENT LEAD S/WV IMPULSE NOW LIFTING ACROSS WYOMING MOVES INTO
EASTERN MONTANA 12-18Z...AND AS THE LLJ BECOMES MORE FOCUSED OVER
WESTERN ND BY 12Z AND SHIFTS EAST INTO CENTRAL ND LATER THIS
MORNING.
SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS MUCH OF THE REGION
TODAY INTO TONIGHT AS ADDITIONAL MID LEVEL WAVES LIFT NORTHEAST
ACROSS THE NORTHERN PLAINS...IN ADVANCE OF THE UPPER LOW (NOW
OVER NORTHERN IDAHO) AS IT TRACKS EAST ACROSS NORTHERN MONTANA. AT
THIS TIME EXPECT THE HEAVIER PRECIPITATION FROM THE AFTERNOON INTO
THE EVENING HOURS ACROSS NORTH DAKOTA WHEN DIFFLUENT FLOW ALOFT
LINKS TO STRONG THERMAL LIFT NORTH OF AN AREA OF LOW PRESSURE
ADVANCING NORTH AND EAST ACROSS SOUTH DAKOTA. THE STRONG SYNOPTIC
FORCING WILL COINCIDE WITH PLENTY OF INSTABILITY AND SHEAR TO
TRIGGER AT LEAST A FEW SEVERE STORMS THROUGH THE PERIOD.
IN ADDITION TO THE FORCING AND SEVERE PARAMETERS...MOISTURE
CONTINUES TO BE PUMPED FROM THE GULF OF MEXICO AROUND THE
SUBTROPICAL RIDGE INTO THE NORTHERN PLAINS. SURFACE TO 300MB
PRECIPITABLE WATER VALUES ARE CURRENTLY OVER 200 PERCENT OF NORMAL
FOR THIS TIME OF YEAR...AND ARE EXPECTED TO INCREASE TO NEAR 2
INCHES TODAY EXCEEDING THE MAXIMUM OBSERVED. THUS ANY STORMS WILL
HAVE THE POTENTIAL TO BE HEAVY RAINERS...SO WE HAVE EXTENDED THE
FLASH FLOOD WATCH THROUGH THIS SUNDAY NIGHT...AND EXPANDED THE
AERIAL COVERAGE TO INCLUDE ALL OF WEST AND CENTRAL NORTH DAKOTA.
ESPECIALLY PRONE TO FLASH FLOODING WILL BE PORTIONS OF WESTERN AND
SOUTHERN NORTH DAKOTA WHICH ALREADY SAW RAINFALL AMOUNTS UP TO
THREE INCHES THE PAST 12-24 HOURS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 415 AM CDT SUN SEP 8 2013
THE MEDIUM RANGE MODELS ARE RELATIVELY SLOWER WITH THE PROGRESSION
OF AN UPPER LEVEL LOW ACROSS NORTH DAKOTA MONDAY. THE LATEST
GUIDANCE NOW PIVOTS THE UPPER TROUGH AXIS ACROSS NORTH DAKOTA
MONDAY NIGHT (INSTEAD OF MONDAY AS GUIDANCE 24 HOURS AGO PROGGED).
AS A RESULT...KEPT CHANCE POPS IN FOR MONDAY...THEN FORECAST A
DECREASING POP TREND FROM SOUTHWEST TO NORTHEAST AS SUBSIDENCE
FILTERS IN BEHIND THE TROUGH AXIS MONDAY NIGHT. LINGERING SLIGHT
CHANCE POPS ARE FORECAST FOR BOTTINEAU...ROLETTE...AND PIERCE
COUNTIES TUESDAY MORNING. HOWEVER...LITTLE IMPACT IS EXPECTED.
DRY CONDITIONS ARE THEN EXPECTED AREAWIDE TUESDAY AFTERNOON THROUGH
FRIDAY AS UPPER LEVEL RIDGING BUILDS OVER THE NORTHERN ROCKIES AND
INTO THE NORTHERN PLAINS. ABOVE NORMAL TEMPERATURES ARE EXPECTED TO
CONTINUE THROUGH THE REMAINDER OF THE WORK WEEK.
ANOTHER ROUND OF PRECIPITATION IS FORECAST FOR SATURDAY AS AN UPPER
LEVEL SHORTWAVE EMANATING FROM THE ROCKIES IS PROGGED TO LIFT INTO
WESTERN NORTH DAKOTA. NOT REAL CONFIDENT WITH THE TIMING OF THIS
FEATURE AS THE MEDIUM RANGE MODELS HAVE RECENTLY BEEN STRUGGLING
WITH SHORTWAVE TIMING ISSUES. WILL CONTINUE TO MONITOR AND MAKE
ADJUSTMENTS AS NEEDED.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 116 PM CDT SUN SEP 8 2013
MVFR CEILING REMAINS AT KISN TO START THE PERIOD. OTHERWISE VFR
CONDITIONS ELSEWHERE. CEILINGS AT KISN SHOULD LIFT TO VFR BY THE
AROUND 21 UTC. EXPECT SHOWER AND THUNDERSTORM CHANCES WILL
INCREASE FROM WEST TO EAST LATE THIS AFTERNOON AND TONIGHT. THEN
KEPT A PERIOD OF MVFR-IFR CEILINGS LATE TONIGHT THROUGH MID
MORNING MONDAY...BEFORE IMPROVING TOWARD THE END OF THE FORECAST
PERIOD.
&&
.HYDROLOGY...
ISSUED AT 415 AM CDT SUN SEP 8 2013
AS MENTIONED ABOVE IN THE SHORT TERM SECTION...HAVE EXPANDED AND
EXTENDED THE FLASH FLOOD WATCH TO INCLUDE ALL OF WESTERN AND
CENTRAL NORTH DAKOTA THROUGH TONIGHT. VERY HIGH ATMOSPHERIC
MOISTURE WILL LINE UP WITH FAVORABLE INSTABILITY AND SYNOPTIC
FORCING TO WARRANT THIS CHANGE. MODELS ARE PROJECTING PWAT VALUES
EXCEEDING THE MAXIMUM OBSERVED FOR THIS TIME OF THE SEASON...NEAR 2
INCHES ACROSS MUCH OF THE REGION.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH MONDAY MORNING FOR NDZ001>005-009>013-
017>023-025-031>037-040>048-050-051.
&&
$$
UPDATE...TWH
SHORT TERM...NH
LONG TERM...TM
AVIATION...TWH
HYDROLOGY...NH
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
104 PM CDT SUN SEP 8 2013
.UPDATE...
ISSUED AT 104 PM CDT SUN SEP 8 2013
AREA OF SHOWERS ACROSS SOUTHERN ND/NORTHERN SD HAS DISSIPATED...
BUT CONVECTION HAS BEEN PERSISTENT ACROSS PORTIONS OF WEST CENTRAL
MN WITH DISSIPATING MCV. UPDATED POPS TO INCLUDE 60S IN THE FAR
SOUTHEASTERN FORECAST AREA AT 18 UTC...BUT THESE SHOWERS AND EMBEDDED
THUNDERSTORMS WILL MOVE QUICKLY INTO EAST-CENTRAL MN FOR THE REST
OF THE AFTERNOON. CLOUD COVER AND RAIN ACROSS THE SOUTHEAST HAS
RESULTED IN VERY COOL TEMPERATURES WITH LITTLE REBOUND. CURRENT
TEMPERATURES ARE STILL IN THE MID TO UPPER 50S...SO DROPPED
AFTERNOON HIGHS SEVERAL DEGREES IN THESE AREAS. REST OF THE
FORECAST THROUGH 00 UTC IN GOOD SHAPE WITH ONLY SCATTERED SHOWERS
POSSIBLE.
UPDATE ISSUED AT 1004 AM CDT SUN SEP 8 2013
FORECAST CONFIDENCE IS LOW AS MODELS HAVE PERFORMED POORLY WITH
ONGOING PRECIPITATION THIS MORNING. WILL FOLLOW THE HRRR FOR THE
MORNING UPDATE...WHICH BEST REFLECTS REALITY.
AREA OF MODERATE SHOWERS WITH ISOLATED EMBEDDED THUNDER STRETCHES
FROM NORTH OF ST. CLOUD TO JUST SOUTH OF GRAND FORKS AND IS IN AN
AREA OF ENHANCED 300 HPA DIVERGENCE AND 850 HPA FRONTOGENESIS.
HRRR SUGGESTS THIS CONVECTION WILL CONTINUE EASTWARD AND DISSIPATE
BY EARLY AFTERNOON. UPDATED POPS TO REFLECT THIS THINKING. ANOTHER
AREA OF SHOWERS STRETCHES FROM SOUTHWEST OF BISMARCK TO EAST OF
ABERDEEN. HRRR SHOWS THIS PRECIPITATION ALSO WEAKENING AS IT MOVES
EAST. HOWEVER...AM NOTICING SOME REDEVELOPMENT ACROSS THE SOUTHERN
VALLEY AS A REMNANT MCV EVIDENT IN RADAR REFLECTIVITY MOVES INTO
THE ND/SD/MN BORDER REGION. WILL NEED TO WATCH THIS FOR THE NEXT
UPDATE...BUT DO NOT ANTICIPATE ANY STRONGER STORMS WITH INSTABILITY
MAXIMIZED FARTHER SOUTH ACROSS WESTERN SD.
OVERALL...ONCE BAND OF SHOWERS/STORMS MOVES OUT OF WEST CENTRAL
MN...THINK THUNDERSTORM COVERAGE WILL BE SCATTERED FOR THE REST
OF THE MORNING AND AFTERNOON AS THE PRIMARY FORCING REMAINS WEST
OF THE FORECAST AREA. ATTENTION TONIGHT WILL TURN TO FLOODING AND
SEVERE POTENTIAL. UPDATED POPS AND WX THOUGH 00 UTC AND ALSO
DECREASED TEMPERATURES A FEW DEGREES WITH PERSISTENT CLOUD COVER.
AFTERNOON HIGHS WILL REACH THE UPPER 60S ALONG THE INTERNATIONAL
BORDER TO THE UPPER 70S ALONG THE SD STATE LINE.
UPDATE ISSUED AT 659 AM CDT SUN SEP 8 2013
VERY COMPLEX PRECIP PATTERN THIS MORNING. NO MODEL HANDLING IT
WELL SO GOING OFF CURRENT RADAR AND ADJUSTING FOR A FEW HOURS
AHEAD FOR IMMEDIATE UPDATES. MAIN MCS DWINDLED IN SE ND/NE SD AS
EXPECTED...BUT OUT AHEAD OF IT SOME CONVECTION FORMED IN THE FARGO
AREA PRODUCING UP TO 1 INCH OF RAIN QUICKLY. THIS CLUSTER MOVING
EAST INTO DTL-FFM AREAS. DID UP POPS REST OF THIS MORNING INTO
WCNTRL MN FOR THIS. OTHERWISE MORE SCATTERED LIGHT ACTIVITY
NORTHWARD INTO THE NRN VALLEY. WOULD APPEAR THIS AFTN TO SEE
SCATTERED ACTIVITY BUT MOST OF THE FOCUS WILL WAIT TIL OVERNIGHT.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 324 AM CDT SUN SEP 8 2013
THREAT FOR HEAVY RAIN TONIGHT IS THERE...BUT WHERE AND HOW MUCH IS
THE MAIN QUESTION. MODEL QPF HAS BEEN RATHER POOR LATELY SO
CONFIDENCE IN AMOUNTS AND EXACT PLACEMENT POOR.
CURRENTLY...HAVE REMAINS OF TSTM COMPLEX THAT WAS IN SW/SCNTRL
ND/NRN SD MOVING EAST SLOWLY AND WEAKENING AS IT ENTERS THE
ABERDEEN-OAKES AREA. BUT HRRR DOES TAKE SOME SHOWERS EAST ACROSS
THE SD/ND BORDER REGION INTO WCNTRL THIS MORNING SO INCLUDED POPS
FOR THIS. HOWEVER IT IS RUNNING INTO QUITE A BIT OF DRY AIR SOON
AND SHOULD START TO REALLY WEAKEN.
MODELS 12Z SAT AND 00Z SUN INDICATED TSTM COMPLEX IN WCNTRL OR NW
ND AT THIS TIME AND INSTEAD DEVELOPMENT HAS BEEN FARTHER SOUTH IN
A NARROW 850 MB LOW LEVEL JET ZONE IN THE DICKINSON-HETTINGER-
BOWMAN AREA OF ND INTO NW SD. THUS PREV FCST IDEA OF LIKELY POPS
SPREADING INTO DVL BASIN THIS MORNING SEEMS A BIT OFF AND REDUCED
POPS TO HIGH CHANCE. RADAR HAS BEEN SHOWING SOME VERY LIGHT
SHOWERS FROM THE MID LEVEL CLOUD COVER MOVING INTO DVL BASIN BUT
WIDESPREAD RAINFALL NOT ANTICIPATED AS FOCUS WILL CONTINUE TO BE
MORE IN SW ND AND THEN INTO CNTRL ND TODAY WITH LOW LEVEL 850 MB
JET AND MOISTURE.
TONIGHT IS THE MAIN ACTION AS SHORT WAVE LIFTS NORTHEAST FROM
MONTANA TROUGH INTO WRN ND AND SFC LOW IS STILL FCST TO TRACK FROM
WRN SD INTO FAR NE SD/SE ND BY 12Z MON. ALL INDICATIONS STILL
FAVOR A LARGE TSTM COMPLEX NORTHWEST OF SFC LOW FROM SW-CNTRL INTO
NE ND/FAR NW MN/SRN MANITOBA OVERNIGHT INTO MONDAY MORNING. KEPT
IDEA OF HVY RAIN MENTIONED IN GRIDDS AND CATEGORICAL POPS MAINLY
NORTH OF A VALLEY CITY-FARGO-BEMIDJI AREAS. GFS IS QUITE STRONG
WITH LOW LEVEL JET (40 KTS) AND HAS MAX 850 INSTABILITY GRADIENT IN
SE-ECNTRL ND-WCNTRL MN 09Z-12Z MON PERIOD AND THUS IDEA OF
ELEVATED SVR VERY POSSIBLE ALONG SRN EDGE OF ANY MCS. FOR RAINFALL
PWATS OF 2 INCHES AT 12Z MON WOULD ARGUE FOR WIDESPREAD 1-2 INCH
RAIN POTENTIAL IN MCS AREA WITH LOCALLY HEAVIER AMOUNTS.
CONSIDERING PAST 60-90 DAYS HAVE BEEN VERY DRY IN OUR REGION RAIN
WILL SOAK INTO THE GROUND WITH RUNOFF MORE LIMITED TO CITY-URBAN
AREAS. AND WITH STILL UNCERTAINTY DUE TO POOR MODEL QPF
PERFORMANCES OF LATE AND THE FACT THAT MAIN RAIN IS TONIGHT HELD
OFF ON ANY FLASH FLOOD WATCHES. BUT SOME MAY BE NEEDED ONCE HVY
RAIN AREA CAN BE PEGGED BETTER.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 324 AM CDT SUN SEP 8 2013
500 MB UPPER TROUGH TO MOVE OVER MANITOBA/NE ND/NW MN MON NIGHT-
TUES AND THUS WILL LEAVE IN LOW POPS FOR THIS.
WEDNESDAY-SATURDAY...BROAD CANADIAN SFC HIGH PRESSURE WILL DROP FROM
CENTRAL CANADA INTO THE GREAT LAKES MID TO LATE WEEK WITH NORTHWEST
FLOW ALOFT...KEEPING THE AREA DRY. MORE SEASONABLE HIGH TEMPS IN
THE 60S TO LOW 70S ARE EXPECTED BY THURSDAY/FRIDAY. THE COOLEST
NIGHT DURING THE PERIOD LOOKS TO BE THURSDAY NIGHT...AS THE SFC HIGH
APPROACHES. TEMPS SHOULD EASILY FALL INTO THE 40S...BUT IT IS
POSSIBLE THAT THESE TEMPS MAY BE TOO WARM...DEPENDING ON THE
EVENTUAL POSITION OF THE SFC HIGH.
BY EARLY NEXT WEEKEND MORE DISAGREEMENT EXISTS AMONG MODELS WITH THE
PATTERN EVOLUTION. HOWEVER...BOTH THE GFS/ECMWF DO BRING A SHORTWAVE
TROUGH INTO THE PLAINS ON SATURDAY...PERHAPS PROVIDING THE NEXT
OPPORTUNITY FOR SOME PRECIPITATION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 104 PM CDT SUN SEP 8 2013
THE MAIN CHALLENGE THROUGH THIS FORECAST WILL BE CIGS AND
CONVECTION. THERE WILL BE A BAND OF IFR/MFVR CIGS IN THE NORTH THAT
MAY PERSIST INTO AT LEAST THIS EVENING. FURTHER SOUTH...EXPECT MORE
VFR CONDITIONS UNTIL STEADY SHOWERS AND STORMS ARRIVE LATER TONIGHT
INTO MONDAY MORNING. RAIN COULD GET HEAVY IN THE NORTH MONDAY
MORNING ALONG WITH WIDESPREAD MVFR TO PERHAPS IFR CONDITIONS NEAR
VERY HEAVY RAIN. FOR NOW HAVE KEPT IT MODERATE SHOWERS FOR
GFK/TVF...BUT THIS AREA COULD BE TARGETED FOR +SHRA/+TSRA FOR THE
12Z MON-18Z MON TIMEFRAME AND WILL MONITOR. IN ADDITION...THERE
COULD BE STRONGER WINDS NEAR THUNDERSTORMS LATE TONIGHT AND MONDAY
MORNING AFFECTING MAINLY SOUTHERN AREAS...BUT WON/T MENTION FOR NOW
BUT CONTINUE TO MONITOR.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...ROGERS
SHORT TERM...RIDDLE
LONG TERM...MAKOWSKI/RIDDLE
AVIATION...DK
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
434 PM EDT SUN SEP 8 2013
.SYNOPSIS...
A COLD FRONT DROPPING SOUTH THROUGH THE STATE WILL USHER IN A
COOLER AND DRIER NORTHERLY FLOW FOR TONIGHT AND MONDAY.
TEMPERATURES WILL QUICKLY RECOVER ON TUESDAY AS A WARM FRONT LIFTS
NORTH ACROSS THE AREA. UNSEASONABLY WARM AND HUMID SUMMER-LIKE
WEATHER IS EXPECTED THROUGH MIDWEEK BEFORE A COLD FRONT MOVES
THROUGH ON THURSDAY. FAIR WEATHER AND SEASONABLY COOL TEMPERATURES
SHOULD RETURN BY THE END OF THE WEEK AS ANOTHER REFRESHING FALL-
LIKE CANADIAN AIR MASS MOVES INTO THE REGION.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
CLEARING SKIES TAKING PLACE EARLY THIS EVENING...AS COLD FRONT
PUSHES SOUTH OF THE AREA AND MUCH DRIER AIR NOW FLOWING INTO THE
STATE ON A NORTHERLY FLOW. LATEST RAP RH FIELDS SUGGEST LINGERING
CU ACROSS SOUTHERN PA WILL DRY UP BY 00Z...LEAVING CLEAR SKIES
FOR THE REST OF THE NIGHT.
THE MODIFIED CANADIAN AIR MASS ACCOMPANYING THIS HIGH PRES SYSTEM IS
NOT QUITE AS COOL AND CHILLY AS THE ONE OF A FEW DAYS PAST.
HOWEVER...STILL CANT RULE OUT SOME PATCHY FROST ACROSS THE COLDER
POCKETS OF THE NRN MTNS WHERE MINS SHOULD DIP INTO THE UPPER 30S
TO AROUND 40F. MID 40S TO LOW 50S WILL BE COMMON ELSEWHERE. ALSO
LOOK FOR FOG TO FORM IN THE NRN RIVER/STREAM VALLEYS TOWARDS DAWN.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
THE HIGH IS EXPECTED TO QUICKLY SLIDE OFF THE EAST COAST MONDAY
SETTING UP A RETURN FLOW OF AIR OUT OF THE SOUTH. SREF/GEFS BOTH
SHOW PWATS OF 1-2 SD ABOVE NORMAL SLIDING BACK INTO WESTERN PA BY
THE END OF THE DAY. SHORT RANGE OPERATIONAL MODELS SHOW THE CHANCE
FOR SHOWERS OVER MY FAR WESTERN ZONES BEFORE NIGHTFALL. SREF AND
GEFS BOTH SHOW SMALL CHANCES FOR RAIN...THE SREF BEING SLIGHTLY
MORE AGGRESSIVE THAN THE GEFS. IT ALL POINTS TO SCATTERED SHOWERS
OR EVEN A THUNDERSTORM BY LATE DAY.
I LEANED TWD A MULTI-MODEL MOS BLEND FOR TOMORROW`S MAX TEMPS
WHICH YIELDS READINGS FROM THE UPPER 60S TO MID 70S FROM NE TO SW.
THIS WILL RANGE FROM NEAR NORMAL OVER THE NORTH TO SEVERAL DEG
COOLER THAN NORMAL OVER THE SOUTHEAST.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
NOT A LOT OF CHANGE FROM YESTERDAY. LOOKING AT A LARGE AREA OF
HIGH PRESSURE BUILDING ACROSS THE REGION...WITH A SLAB OF HOT
AIR FROM THE HIGH SOUTHERN PLAINS MOVING EASTWAFD. WITH AN EML
AIRMASS IN PLACE...AND A TENDENCY TO CAP ANY CONVECTION...THINK
VERY LITTLE CHC OF RAIN WITH WARM FRONT LATE MONDAY NIGHT...AND
NOT MUCH IN THE WARM SECTOR ON WED...MAYBE A FEW STORMS LATE.
DID UP TEMPS SOME AND LOWER POPS A LITTLE.
HIGHEST CHC OF STORMS WILL BE ON THU...AS COLD FRONT NEARS.
COMPLEX FRONT...MORE LIKE 2 COLD FRONTS.
COLDER AIR FOR LATE IN THE WEEK...BUT THIS IS COMPLEX TOO.
EC RUNS HINT AT LESS HIGH PRESSURE MAY BUILD IN...AND UPPER LVL
TROUGH COULD TRY TO CLOSE OFF JUST EAST OF THIS AREA.
AS FAR AS LAKE EFFECT GOES...HARD TO SEE MUCH...PERHAPS SOME
LATER ON FRIDAY...AS COLD AIR DEEPENS...AND WINDS ALOFT BECOME
MORE NW.
THE MAIN STORY WILL BE THE HEAT. MANY SPOTS WILL LIKELY SEE
90 DEGREES...BETWEEN TUE AND LATE THU...AS PLUS 18 DEGREE AIR
OR HIGHER MOVES IN AT 850 MB ON WESTERLY FLOW. NAM STILL THE
WARMEST MODEL.
NOT SURE I BUY INTO THE HIGH DEWPOINTS ON TUE...ETC...WITH THIS
AIRMASS...GIVEN WHERE THE AIRMASS COMES FROM. WHILE THERE WILL BE
POTENTIAL FOR STRONG STORMS AT SOME POINT...THIS WILL LARGELY
DEPEND ON HOW MUCH LOW LVL MOISTURE WORKS INTO THE AREA. ANYWAY...
ENJOY THE LATE SUMMER WEATHER...AS WE MAKE UP FOR WHAT WAS A WET
EARLY SUMMER.
&&
.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
THE SFC COLD FRONT IS CLEARING MY SERN ZONES AS OF EARLY
AFTERNOON. STILL A BAND OF CLOUDS BEHIND THE FRONT WITH MVFR CIGS
HANGING IN OVER THE AREA FROM JST-AOO NORTHWARD. STILL EXPECTING
DRY AIR TO MIX IN AND ALLOW FOR IMPROVEMENT TO VFR AT ALL SITES BY
MID AFTERNOON.
HIGH PRES WILL MOVE INTO THE AIRSPACE TONIGHT WITH SFC WINDS
SHIFTING FROM NORTH TO ENE-SSE AND BECOMING LIGHT. FOG IS POSSIBLE
OVER THE NRN RIVER VALLEYS LATE TONIGHT UNTIL SHORTLY AFTER
SUNRISE MONDAY UNDER THE CLEAR SKIES AND LIGHT WINDS.
THE FOG WILL LIFT MONDAY MORNING AND ALL SITES WILL BECOME VFR BY
MID MORNING...AND REMAIN SO THROUGHOUT THE DAY. COULD BE A LATE
DAY SHOWER OR THUNDERSTORM OVER WESTERN SXNS.
OUTLOOK...
TUE...AM FOG PSBL. ISOLD PM TSTM IMPACTS PSBL.
WED...SCT PM TSTM IMPACTS PSBL.
THU...SCT-NMRS TSTM IMPACTS PSBL WITH COLD FROPA.
FRI...NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...FITZGERALD/LA CORTE
SHORT TERM...LA CORTE
LONG TERM...MARTIN
AVIATION...LA CORTE
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
110 PM CDT SUN SEP 8 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 409 AM CDT SUN SEP 8 2013
COMPLEX OF STORMS ACROSS NORTH CENTRAL SOUTH DAKOTA IS EXPECTED TO
SHIFT EAST THIS MORNING AND MAY SCRAPE THE NORTHERN EDGE OF THE
FORECAST AREA THIS MORNING. APPEARS AS THOUGH STORMS ARE DEVELOPING
BEHIND THE LEADING EDGE OF WARM AIR/THETA-E ADVECTION IN A MORE
UNSTABLE ENVIRONMENT. HI RES MODELS HANDLING THE SHORT TERM
RELATIVELY POORLY...WITH MOTH THE RAP AND THE HRRR SUGGESTING THE
ACTIVITY WOULD REMAIN WELL TO THE NORTH NEAR THE NORTH DAKOTA
BORDER. IN GENERAL...WIND SHEAR APPEARS TO BE FAIRLY WEAK SO AM NOT
ANTICIPATING SEVERE WEATHER THROUGH THE MORNING WITH THIS ACTIVITY
AS IT WORKS EAST.
INCREASING SOUTHERLY FLOW ACROSS THE AREA TODAY WILL LEAD TO ANOTHER
WARM AND HUMID DAY ACROSS THE REGION. HAVE TRIMMED BACK FORECAST
HIGHS IN THE NORTH WITH EXPECTED CONVECTION AND CLOUD COVER LIMITING
HEATING POTENTIAL SOME. WITH 925 HPA WINDS INCREASING TO NEAR 20
KNOTS...SHOULD SEE GUSTY WINDS OF 15-20 KNOTS.
EXPECT WIND GUSTS TO DROP OFF THROUGH THE EVENING...BUT SHOULD BE A
FAIRLY WARM NIGHT ACROSS THE REGION WITH SUSTAINED WINDS REMAINING
IN THE 10-15 KNOT RANGE. MODELS SUGGEST A SECONDARY WARM FRONT WILL
LIFT THROUGH THE REGION AND MAY BECOME THE FOCUSING MECHANISM FOR
ELEVATED STORMS ACROSS SOUTHWEST MINNESOTA AND ADJACENT AREAS. WENT
AHEAD AND INCREASED POPS FOR THIS AREA...WITH THE POTENTIAL FOR A
FEW STORMS TO BE MARGINALLY SEVERE WITH STRONGLY VEERING WIND SHEAR
PROFILES.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 409 AM CDT SUN SEP 8 2013
THE COLD FRONT WILL WORK ITS WAY ACROSS THE CWA MONDAY AFTERNOON
INTO THE OVERNIGHT HOURS. LOOKS LIKE GOOD HEATING POTENTIAL AHEAD OF
THE FRONT...WITH A SOUTHWESTERLY BREEZE GUSTING TO AROUND 30 MPH AND
COMPRESSIONAL HEATING. GIVEN OUR LACK OF GOOD MIXING RECENTLY...WAS
HESITANT TO GO TOO WARM WITH HIGHS...SO WHILE I DID GO HIGHER THAN
THE COOL BIAS CORRECTED VALUES...DID NOT GO WITH FULL MIXING TO 850
MB. FRONTAL TIMING IS STILL A BIT UNCERTAIN...AND THIS WILL HAVE AN
IMPACT ON HIGHS AS WELL. HIGHEST READINGS SHOULD BE ACROSS NORTHWEST
IOWA AND PORTIONS OF SOUTHWEST MINNESOTA...WHERE MID AND A FEW UPPER
90S SEEM PROBABLE. THE MARSHALL TO SIOUX FALLS TO YANKTON CORRIDOR
HAS THE HIGHER UNCERTAINTY...HOWEVER MOST MODEL SOLUTIONS KEEP THE
FRONT SLOW ENOUGH TO ALLOW THESE AREAS TO WARM INTO THE LOW TO MID
90S. CURRENTLY LOOKS LIKE HEAT INDICES WILL BE IN THE MID TO UPPER
90S...BUT SHOULD REMAIN BELOW 100...WITH THE INCREASED MIXING ALSO
HELPING TO LOWER DEWPOINTS SOME AHEAD OF THE FRONT.
LOOKING AT TWO POTENTIAL CHANCES FOR PRECIPITATION WITH THE FRONTAL
PASSAGE. THE PRE FRONTAL ATMOSPHERE SHOULD GENERALLY REMAIN CAPPED
THROUGH THE DAY. HOWEVER...RIGHT ALONG AND JUST BEHIND THE
FRONT...INDICATIONS THAT MOISTURE POOLING WILL RESULT IN AN INCREASE
IN DEWPOINTS. IT IS POSSIBLE THAT THIS...COMBINED WITH
FRONTOGENETICAL FORCING WILL BE ENOUGH TO BREAK THE CAP. IF THIS
HAPPENS IT WOULD LIKELY BE IN THE 21Z TO 03Z TIMEFRAME....GENERALLY
ALONG AND NORTHWEST OF A YANKTON TO WORTHINGTON LINE. THIS IMMEDIATE
POST FRONTAL ATMOSPHERE SHOULD BE CHARACTERIZED BY CAPE AROUND 1500
J/KG AND EFFECTIVE DEEP LAYER SHEAR OF ABOUT 30 KTS. SO WHILE
NOTHING TOO IMPRESSIVE...THESE PARAMETERS ARE ENOUGH TO SUGGEST AN
ISOLATED SEVERE STORM WOULD BE POSSIBLE. THE SECOND THREAT WILL BE
AS THE MAIN UPPER WAVE PASSES TO OUR NORTH. WHILE THE BEST PV
ADVECTION WILL REMAIN NORTH...A 60 TO 80 KT UPPER JET PASSING TO OUR
NORTH WILL PUT US IN FAVORED THE RIGHT ENTRANCE REGION. WHILE THIS
UPPER LEVEL SUPPORT APPEARS TOO LATE TO HELP WITH THE NEAR SURFACED
BASED CONVECTION POTENTIAL DISCUSSED ABOVE...IT MAY INTERACT WITH
THE 700 MB FRONT AND ALLOW FOR THE DEVELOPMENT OF ADDITIONAL SHOWER
AND THUNDERSTORMS FROM ABOUT 06Z ON. BY THIS TIME...MID LEVEL LAPSE
RATES BECOME PRETTY WEAK...AND THUS ELEVATED INSTABILITY WILL BE
LOW. MAYBE ENOUGH TO GET THUNDER...BUT WOULD NOT EXPECT ANYTHING
SEVERE WITH THIS ACTIVITY. WITH PWATS RUNNING 2 TO 3 STANDARD
DEVIATIONS ABOVE NORMAL...AND STORM MOTIONS NEARLY PARALLEL TO THE
MID LEVEL FRONT...LOCALLY HEAVY RAIN WOULD BE POSSIBLE. WILL JUST
KEEP HIGH CHANCE POPS FOR NOW...AS THE OVERNIGHT ACTIVITY WILL
PROBABLY BE PRETTY NARROW AND FOCUSED CLOSE TO THE 700 MB
FRONT...AND UNCERTAINTY EXISTS ON WHERE EXACTLY THIS WILL SET UP.
ALSO SOME MODEL RUNS ARE PRETTY WEAK ON QPF...POSSIBLY DUE TO THE
WEAK INSTABILITY AND A BIT OF A DRY LAYER AROUND 850 MB...SO WHILE
IT LOOKS LIKE A GOOD CHANCE MONDAY NIGHT...WILL CONTINUE TO HOLD OFF
ON LIKELY POPS FOR THE TIME BEING.
MODELS TRENDING TOWARDS STALLING THE FRONT FURTHER SOUTH THAN
PREVIOUSLY THOUGHT. THIS WILL PROBABLY LIMIT THE PRECIP POTENTIAL
TUESDAY INTO TUESDAY NIGHT...BUT WILL KEEP A SMALL POP GOING ACROSS
NORTHWEST IOWA. WE WILL SEE COOLER TEMPERATURES FILTER IN BEHIND THE
FRONT TUESDAY INTO WEDNESDAY AS THE RIDGE FLATTENS. ALTHOUGH STILL
EXPECTING ABOVE NORMAL READINGS IN THE LOW TO MID 80S. DEWPOINTS MAY
LINGER IN THE LOW 60S TUESDAY...BUT SHOULD FINALLY DROP INTO THE 50S
BY WEDNESDAY...BRINGING AN END TO THE HUMID PERIOD. A STRONG WAVE
MOVING ACROSS SOUTHERN CANADA WILL HELP PUSH A A BACKDOOR COLD FRONT
AND EVEN COOLER AND LESS HUMID CONDITIONS INTO THE REGION THURSDAY
INTO FRIDAY. EXPECTING HIGHS IN THE 70S BOTH DAYS...WITH ONLY AREAS
NEAR THE MISSOURI RIVER POTENTIALLY HITTING 80. ALSO WOULD EXPECT
COOLER NIGHTTIME TEMPERATURES WITH HIGH PRESSURE CENTERED TO OUR
NORTHEAST. FRIDAY MORNING CURRENTLY LOOKS TO BE THE
COOLEST...POSSIBLY BEING THE FIRST NIGHT IN A WHILE WHERE LOWS
ACTUALLY END UP BELOW NORMAL...IN THE UPPER 40S TO MID 50S. AS THE
RIDGE BEGINS TO BUILD BACK IN LATER FRIDAY INTO SATURDAY...THE
THUNDERSTORM THREAT SHOULD AGAIN BEGIN TO INCREASE OVER THE REGION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1259 PM CDT SUN SEP 8 2013
NEAR TERM CONCERNS ARE STRATUS AND THEN WIND SHAR. A LARGE AREA OF
STRATUS CONTINUES TO TRY TO SPREAD EAST FROM SW MN AND NW IA AND
INTO SE SE. DO HAVE A BREIF PERIOD OF BKN STRATUS EARLY THIS
AFTERNOON AROUD KFSD. HOWEVER...COULD SEE BKN-OVC STRATUS AT KHON
AND KFSD THROUGH MUCH OF THE AFTERNOON AND EVENING AS AMPLE LOW
LEVEL MOISTURE REMAINS TRAPPED BELOW A VERY STRONG INVERSION.
IF STRATUS IS MAINTAINED IT COULD LAST THROUGH 06Z AT BOTH
LOCATIONS.
OVERNIGHT...A STRONG SOUTHWESTERLY LOW LEVEL JET OF 40 TO 50 KTS WILL
DEVELOP AND WITH WINDS AT THE SURFACE SOUTHEAST AROUND 10
KTS...THERE WILL BE SOME LOW LEVEL WIND SHEAR LATER TONIGHT ACROSS
THE AREA. IN ADDITION...ISOALTED THUNDERSTORMS MAY FORM NORTHEAST
OF SIOUX FALLS BUT ANY STORMS ARE NOT EXPECTED TO AFFECT TAF
LOCATIONS. OTHERWISE...A COLD FRONT WILL MOVE INTO SOUTHEAST SOUTH
DAKOTA DURING THE MORNING WITH THE FRONT EXPECTED TO MOVE THROUGH
KHON AROUND 15Z...AND KFSD BETWEEN 18Z AND 20Z. ANY PRECIPITATION
IS EXPECTED TO HOLD OFF UNTIL AFTER 21Z MONDAY WITH THE BEST
CHANCE AFTER 00Z TUESDAY.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...CHENARD
AVIATION...SCHUMACHER
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
155 PM CDT SUN SEP 8 2013
.UPDATE...
Adjusted POPS and temperatures for the remainder of the afternoon
hours.
&&
.DISCUSSION...
Isolated to widely scattered showers are developing across southern
sections early this afternoon. Based on latest observational trends
and recent HRRR data, should see a bit better coverage across
southern sections. POPS were increased slightly across the Northern
Edwards Plateau and Northwest Hill Country counties where scattered
convection is expected. Also increased cloud cover across southern
sections and decreased max temps a couple of degrees based on
current trends. Highs should top out in the upper 80s along the
I-10 corridor to the mid and upper 90s across the Big
Country.
&&
.PREV DISCUSSION... /ISSUED 1230 PM CDT SUN SEP 8 2013/
DISCUSSION...
See 18Z aviation discussion below.
AVIATION...
Isolated to widely scattered convection will be possible across
the southern terminals this afternoon. Thunder should be limited
but did include VCSH at both the KJCT and KSOA terminals after 20Z.
Brief MVFR conditions possible with any of the showers and will
amend as necessary based on convective trends. Stratus returns to
the southern terminals after 09Z Monday with MVFR conditions
expected at KJCT, KSOA and KBBD through mid/late morning hours.
PREV DISCUSSION... /ISSUED 621 AM CDT SUN SEP 8 2013/
DISCUSSION...
See 12Z aviation discussion below.
AVIATION...
Scattered areas of low level stratus are moving north across mainly
the Northern Edwards Plateau and Northwest Hill Country. Will keep
the southern terminals VFR and keep an eye low cloud trends the next
few hours for possible amendments. Otherwise, expect VFR conditions
the next 24 hours. Isolated showers and thunderstorms will be
possible this afternoon across the southern 1/3, mainly south of a
San Angelo to Brownwood line. Will not include in the TAFS due to
very limited coverage.
21
PREV DISCUSSION... /ISSUED 338 AM CDT SUN SEP 8 2013/
SHORT TERM...
/Today and Tonight/
An upper level high was over the Central Plains this morning,
with upper level easterly flow over West Central Texas. At the
surface, low level moisture was increasing across the area with
dewpoints in the 60s. Mild temperatures prevailed with readings
in the 70s.
The upper level high will still have an influence across West
Central Texas today. However, the combination of the upper level
easterly flow and some instability will lead to the possibility of
isolated afternoon and early evening showers and thunderstorms
across southern areas, mainly south of a San Angelo to Brownwood
line. The thunderstorms will have the potential to produce
dangerous lightning and gusty winds. Highs will be in the 90s. The
warmest readings/upper 90s/ will be across the Northern Big
Country a little closer to the 850 MB thermal ridge.
Isolated convection will dissipate by 02Z Monday. Otherwise for
tonight, expect mostly clear skies with lows mainly in the lower
70s.
21
LONG TERM...
/Monday through Saturday/
Continued warm, with possible isolated afternoon showers and
thunderstorms through Tuesday.
By Monday...the upper level ridge currently centered in the
Central Plains will be in the process of re-centering over the
southeastern U. S. The result in our area will be deep, moist,
southeasterly flow from Monday into the mid week. Thus, we could
see continue to see isolated showers and thunderstorms,
especially across our southern counties that will have better low
level moisture to work with. So, will go ahead with isolated
thunderstorm wording for areas mainly south of a Barnhart to San
Saba line for Monday afternoon, and a slight chance on Tuesday
afternoon for roughly the same area. With the high sliding off to
the east, and better moisture moving into the area, we could see
some slight relief from the hot temperatures, and have cooler our
highs through the next several days a few degrees. However, we
will still remain a few degrees above normal through the end of
the forecast period.
Beyond Tuesday, kept the forecast dry for now. The GFS shows a
distinct upper low moving across our southern counties Thursday.
However the EC is much weaker with the same feature, and the GFS
has been inconsistent as far as path and timing for the same
feature, so it`s hard to trust it wholly at this point.
20
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 95 70 93 69 91 / 10 5 5 5 5
San Angelo 93 70 91 69 91 / 20 10 10 5 20
Junction 89 71 89 67 89 / 30 20 10 10 20
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
99/99