Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/30/14
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1126 AM MDT THU AUG 28 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 408 AM MDT THU AUG 28 2014
CURRENT WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS INDICATING A
BROAD UPPER TROUGH MOVING ACROSS THE ROCKIES...WITH A DISTINCT
CIRCULATION ACROSS NORTH CENTRAL COLORADO AT THIS TIME. WATER VAPOR
IMAGERY IS ALSO INDICATING THE MAIN MONSOONAL MOISTURE PLUME HAS
PUSHED EAST ACROSS THE SOUTHERN HIGH PLAINS AND INTO THE UPPER
MIDWEST...WITH CURRENT DRY SLOT ACROSS THE SE PLAINS DECREASING AS
EMBEDDED MOISTURE ASSOCIATED WITH THE TROUGH IS MOVING EAST.
TODAY...WILL SEE NORTHWEST FLOW ALOFT INCREASING THROUGH THE DAY AS
THE UPPER TROUGH AND MAIN VORT MAX CONTINUES TO LIFT NORTH AND EAST
INTO THE THE NORTHERN HIGH PLAINS. THE LATEST NAM AND GFS CONTINUE
TO INDICATE MORE WIDESPREAD PRECIPITATION ACROSS THE AREA AND HAVE
FOLLOWED THE HIGHER RESOLUTION NSSL WRF...HRRR AND RAP WHICH SEEM TO
HAVE PICKED UP ON FURTHER NORTH MOVEMENT OF THE SYSTEM AND ARE
KEEPING THE BEST CHANCES OF SHOWERS OVER AND NEAR THE NORTHERN AND
CENTRAL MTS WITH THE DEVELOPING NORTHWEST FLOW ALOFT. SHOULD ALSO
SEE ISOLATED TO SCATTERED SHOWERS AND STORMS DEVELOPING LATE THIS
MORNING OVER AND NEAR THE REST OF THE HIGHER TERRAIN SPREADING SOUTH
AND EAST ACROSS THE EASTERN PLAINS THROUGH THE AFTERNOON...WITH BEST
COVERAGE OVER NORTHERN PORTIONS OF THE SE PLAINS. THE NORTHERLY FLOW
WILL KEEP BEST LOW LEVEL MOISTURE WELL EAST OF THE AREA WITH THE
MAIN THREATS FROM STORMS TODAY BEING LIGHTNING AND GUSTY WINDS UP TO
40 MPH...THOUGH CANT RULE OUT LOCALIZED BRIEF HEAVY RAINFALL AND
SMALL HAIL WITH THE MORE INTENSE CELLS. WITH COOLING ALOFT...SHOULD
CONTINUE TO SEE BELOW SEASONAL TEMPERATURES IN THE 70S TO LOWER 80S
ACROSS THE PLAINS...50S AND 60S ACROSS THE HIGHER TERRAIN AND MAINLY
30S AT THE PEAKS...LEADING TO THE POTENTIAL FOR LIGHT SNOW
ACCUMULATIONS AOA 12K FT TODAY.
TONIGHT...SUBSIDENT NORTHWEST FLOW ALOFT CONTINUES TO MOVE ACROSS
THE STATE AND SHOULD SEE CLOUDS AND STORMS DIMINISHING FROM WEST TO
EAST THROUGH THE EVENING HOURS WITH MOSTLY CLEAR SKIES OVERNIGHT
WITH AT OR BELOW NORMAL LOWS EXPECTED TONIGHT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 408 AM MDT THU AUG 28 2014
FRIDAY THE UPR TROF WL BE EAST OF THE STATE AND AN UPR RIDGE WL BE
BUILDING OVR THE AREA. RESIDUAL MSTR AND AFTERNOON INSTABILITY WL
PROBABLY LEAD TO SOME ISOLD SHOWERS AND TSTMS...MAINLY OVR THE HYR
TRRN. HIGH TEMPS ON FRI SHOULD BE CLOSE TO OR JUST SLIGHTLY BELOW
AVERAGE. SAT AN UPR TROF OVR THE NRN ROCKIES WL BRING WESTERLY FLOW
ALOFT OVR THE STATE. MSTR OVR THE AREA INCREASES A LITTLE...ALTHOUGH
THE NAM SHOWS MORE MSTR AND BETTER PCPN CHANCES THAN THE GFS. FOR
NOW WL STICK WITH JUST SOME ISOLD TO SCT POPS OVR THE HYR TRRN...BUT
IF THE NAM SOLUTION IS CORRECT...THERE COULD BE BETTER PCPN COVERAGE
WHICH ALSO SPREADS OVR THE LOWER ELEVATIONS. HIGHS ON SAT SHOULD BE
AROUND TO SLIGHTLY ABOVE AVERAGE. SAT NIGHT AN UPR TROF MOVES ACRS
CO AND THE NAM HAS SOME PCPN ACRS MUCH OF THE AREA THRU THE
NIGHT...WHILE THE GFS AND ECMWF ARE DRIER. SUN...A COLD FRONT IS
EXPECTED TO DROP INTO SERN CO IN THE AFTERNOON HOURS. THE BEST UPR
FORCING SUN IS EXPECTED TO BE NORTH OF THE AREA...BUT SOME ISOLD
PCPN MAY DEVELOP OVR THE MTNS IN THE AFTERNOON HOURS...AND SOME MAY
ALSO DEVELOP OVER THE SERN PLAINS ALONG AND BEHIND THE FRONT. DRY
WESTERLY FLOW ALOFT IS EXPECTED FOR LABOR DAY...WITH SHALLOW UPSLOPE
FLOW DEVELOPING LATE MON OVR THE ERN MTNS AND PLAINS. THE AIR MASS
LOOKS FAIRLY DRY ON MON SO WL KEEP THE FORECAST DRY. LOW LEVEL
UPSLOPE CONTINUES ON TUE AND SOME ISOLD CONVECTION MAY DEVELOP OVR
THE HYR TRRN. ON WED THE UPR FLOW BECOMES MORE SWRLY AS AN UPR TROF
MOVES INTO THE PACNW AND THE UPR TROF EXTENDS SOUTHWARD JUST OFF THE
CA COAST. MSTR STILL LOOKS LIMITED OVR THE FORECAST AREA AND MAY
JUST SEE SOME ISOLD CONVECTION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1123 AM MDT THU AUG 28 2014
REGION IS ON THE BACKSIDE OF UPPER TROUGH. SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS WILL OCCUR THIS AFTERNOON WITH STORMS
MOVING SOUTHEAST AT 15 TO 20 MPH. OVERALL PRECIP...IF IT
OCCURS...WILL GENERALLY BE LIGHT AND BRIEF WITH ONLY BRIEF PDS OF
MVFR IN HEAVIER SHOWERS. WINDS WILL BE LIGHT BUT SHOULD PICK UP
FROM THE NORTHWEST AT 6 TO 12 KNTS BY LATER AFTERNOON.
VFR EXPECTED BY EARLY EVENING AT ALL 3 TAF SITES...KPUB...KALS AND
KCOS. VFR WILL LAST THROUGH TOMORROW.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MW
LONG TERM...28
AVIATION...HODANISH
AREA FORECAST DISCUSSION
NWS PUEBLO CO
409 AM MDT THU AUG 28 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 408 AM MDT THU AUG 28 2014
CURRENT WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS INDICATING A
BROAD UPPER TROUGH MOVING ACROSS THE ROCKIES...WITH A DISTINCT
CIRCULATION ACROSS NORTH CENTRAL COLORADO AT THIS TIME. WATER VAPOR
IMAGERY IS ALSO INDICATING THE MAIN MONSOONAL MOISTURE PLUME HAS
PUSHED EAST ACROSS THE SOUTHERN HIGH PLAINS AND INTO THE UPPER
MIDWEST...WITH CURRENT DRY SLOT ACROSS THE SE PLAINS DECREASING AS
EMBEDDED MOISTURE ASSOCIATED WITH THE TROUGH IS MOVING EAST.
TODAY...WILL SEE NORTHWEST FLOW ALOFT INCREASING THROUGH THE DAY AS
THE UPPER TROUGH AND MAIN VORT MAX CONTINUES TO LIFT NORTH AND EAST
INTO THE THE NORTHERN HIGH PLAINS. THE LATEST NAM AND GFS CONTINUE
TO INDICATE MORE WIDESPREAD PRECIPITATION ACROSS THE AREA AND HAVE
FOLLOWED THE HIGHER RESOLUTION NSSL WRF...HRRR AND RAP WHICH SEEM TO
HAVE PICKED UP ON FURTHER NORTH MOVEMENT OF THE SYSTEM AND ARE
KEEPING THE BEST CHANCES OF SHOWERS OVER AND NEAR THE NORTHERN AND
CENTRAL MTS WITH THE DEVELOPING NORTHWEST FLOW ALOFT. SHOULD ALSO
SEE ISOLATED TO SCATTERED SHOWERS AND STORMS DEVELOPING LATE THIS
MORNING OVER AND NEAR THE REST OF THE HIGHER TERRAIN SPREADING SOUTH
AND EAST ACROSS THE EASTERN PLAINS THROUGH THE AFTERNOON...WITH BEST
COVERAGE OVER NORTHERN PORTIONS OF THE SE PLAINS. THE NORTHERLY FLOW
WILL KEEP BEST LOW LEVEL MOISTURE WELL EAST OF THE AREA WITH THE
MAIN THREATS FROM STORMS TODAY BEING LIGHTNING AND GUSTY WINDS UP TO
40 MPH...THOUGH CANT RULE OUT LOCALIZED BRIEF HEAVY RAINFALL AND
SMALL HAIL WITH THE MORE INTENSE CELLS. WITH COOLING ALOFT...SHOULD
CONTINUE TO SEE BELOW SEASONAL TEMPERATURES IN THE 70S TO LOWER 80S
ACROSS THE PLAINS...50S AND 60S ACROSS THE HIGHER TERRAIN AND MAINLY
30S AT THE PEAKS...LEADING TO THE POTENTIAL FOR LIGHT SNOW
ACCUMULATIONS AOA 12K FT TODAY.
TONIGHT...SUBSIDENT NORTHWEST FLOW ALOFT CONTINUES TO MOVE ACROSS
THE STATE AND SHOULD SEE CLOUDS AND STORMS DIMINISHING FROM WEST TO
EAST THROUGH THE EVENING HOURS WITH MOSTLY CLEAR SKIES OVERNIGHT
WITH AT OR BELOW NORMAL LOWS EXPECTED TONIGHT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 408 AM MDT THU AUG 28 2014
FRIDAY THE UPR TROF WL BE EAST OF THE STATE AND AN UPR RIDGE WL BE
BUILDING OVR THE AREA. RESIDUAL MSTR AND AFTERNOON INSTABILITY WL
PROBABLY LEAD TO SOME ISOLD SHOWERS AND TSTMS...MAINLY OVR THE HYR
TRRN. HIGH TEMPS ON FRI SHOULD BE CLOSE TO OR JUST SLIGHTLY BELOW
AVERAGE. SAT AN UPR TROF OVR THE NRN ROCKIES WL BRING WESTERLY FLOW
ALOFT OVR THE STATE. MSTR OVR THE AREA INCREASES A LITTLE...ALTHOUGH
THE NAM SHOWS MORE MSTR AND BETTER PCPN CHANCES THAN THE GFS. FOR
NOW WL STICK WITH JUST SOME ISOLD TO SCT POPS OVR THE HYR TRRN...BUT
IF THE NAM SOLUTION IS CORRECT...THERE COULD BE BETTER PCPN COVERAGE
WHICH ALSO SPREADS OVR THE LOWER ELEVATIONS. HIGHS ON SAT SHOULD BE
AROUND TO SLIGHTLY ABOVE AVERAGE. SAT NIGHT AN UPR TROF MOVES ACRS
CO AND THE NAM HAS SOME PCPN ACRS MUCH OF THE AREA THRU THE
NIGHT...WHILE THE GFS AND ECMWF ARE DRIER. SUN...A COLD FRONT IS
EXPECTED TO DROP INTO SERN CO IN THE AFTERNOON HOURS. THE BEST UPR
FORCING SUN IS EXPECTED TO BE NORTH OF THE AREA...BUT SOME ISOLD
PCPN MAY DEVELOP OVR THE MTNS IN THE AFTERNOON HOURS...AND SOME MAY
ALSO DEVELOP OVER THE SERN PLAINS ALONG AND BEHIND THE FRONT. DRY
WESTERLY FLOW ALOFT IS EXPECTED FOR LABOR DAY...WITH SHALLOW UPSLOPE
FLOW DEVELOPING LATE MON OVR THE ERN MTNS AND PLAINS. THE AIR MASS
LOOKS FAIRLY DRY ON MON SO WL KEEP THE FORECAST DRY. LOW LEVEL
UPSLOPE CONTINUES ON TUE AND SOME ISOLD CONVECTION MAY DEVELOP OVR
THE HYR TRRN. ON WED THE UPR FLOW BECOMES MORE SWRLY AS AN UPR TROF
MOVES INTO THE PACNW AND THE UPR TROF EXTENDS SOUTHWARD JUST OFF THE
CA COAST. MSTR STILL LOOKS LIMITED OVR THE FORECAST AREA AND MAY
JUST SEE SOME ISOLD CONVECTION.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 408 AM MDT THU AUG 28 2014
ANOTHER ROUND OF ENERGY FROM THE UPPER TROUGH WILL MOVE ACROSS THE
AREA THURSDAY MORNING AND WILL RESULT IN AN EARLY START TO SHOWERS
AND STORMS ACROSS THE HIGHER TERRAIN THURSDAY MORNING WITH SHOWERS
POSSIBLE IN THE VCNTY OF ALS AND COS BY 16Z. STRONGER SHOWERS AND
STORMS WILL HOLD OFF UNTIL AFTER 18Z...THOUGH WITH MAIN PORTION OF
THE SYSTEM LIFTING NORTH...WITH KEEP VCTS AT TAF SITES AT THIS TIME
WITH BEST CHANCES OF A STORM AFFECTING THE TERMINAL AT COS. MAINLY
VFR CONDITIONS EXPECTED AT TAF SITES WITH BRIEF MVFR CONDITIONS
POSSIBLE WITH STORMS. STORMS TO DIMINISH FROM WEST TO EAST THROUGH
THE LATE AFTERNOON AND EARLY EVENING WITH CLEARING SKIES EXPECTED
OVERNIGHT.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MW
LONG TERM...28
AVIATION...MW
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1145 PM MDT WED AUG 27 2014
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 240 PM MDT WED AUG 27 2014
...FEW STRONG STORMS POSSIBLE LATER TODAY AND THIS EVENING...SOME
SNOW AT THE HIGHEST PEAKS...
CURRENTLY...
VERY WELL DEFINED UPPER LOW AS SEEN BY WATER VAPOR IMGY WAS SPINNING
OVER NE UTAH. A VORT LOBE FROM THIS SYSTEM WAS OVER WESTERN COLORADO
AS A LINE OF TSRA WAS ADVANCING EAST OVER THIS REGION. OVER THE NWS
PUB CWA...A DRY SLOT ASSOCIATED WITH THIS UPPER LVL LOW WAS OVER THE
WESTERN 1/2 OF THE PLAINS...AS SKIES WERE GENERALLY SUNNY. TEMPS
OVER THE PLAINS HAVE WARMED UP INTO THE 80S GENERALLY BELOW 5500
FEET...WITH 60S AND 70S MOST OTHER LOCATIONS. LOOKING AT THE
THERMODYNAMIC FIELDS...CAPE VALUES FROM THE SPC WERE IN THE 1000
RANGE WHILE FARTHER EAST VALUES WERE 2500 J/KG. EFFECTIVE DEEP SHEAR
WAS 30-35 KNTS.
AT THE SFC ACROSS THE REGION...A WEEK COOL FRONT WAS CLEARLY SEEN IN
THE VIS SAT PIX IMGY ALONG THE EL PASO/DOUGLAS/ELBERT COUNTY LINE
AND IT WAS PROGRESSING SLOWLY SWD.
REST OF THIS AFTERNOON AND EVENING...
VORT LOBE OVER W CO WILL LIKELY START AFFECTING THE GREATER PIKES
PEAK REGION LATE THIS AFTERNOON AND INTO THIS EVENING. HRRR REALLY
DOES NOT GET THINGS GOING UNTIL AFTER 9 PM...AND I BELIEVE THIS IS
TOO LATE AS THINGS WILL LIKELY GET GOING BY VERY LATE AFTERNOON OR
EARLY EVENING. AS MENTIONED ABOVE...SHEAR AND CAPE ARE INCREASING
AND I DO EXPECT WE WILL SEE A FEW SUPERCELLS OVER THE EASTERN PLAINS
OF COLORADO. SPC RECENTLY ISSUED AN MCD DISCUSSING THIS THREAT.
WALDO WILL ALSO NEED TO BE WATCHED. ALTHOUGH STORMS WILL MOVE AT A
GOOD CLIP TODAY...ATMOSPHERE HAS PLENTY OF MOISTURE AND ANY HEAVY
RAIN OVER A SHORT PERIOD OF TIME WILL CAUSE ISSUES OVER THE BURN
SCARS.
OVERALL...I BELIEVE BEST CHANCE OF SEVERE WILL GENERALLY BE ALONG
AND NORTH OF HIGHWAY 50...ASSOCIATED WITH SOUTHWARD MOVING
BOUNDARY...ALTHOUGH STRONG STORMS COULD OCCUR ANYWHERE ACROSS THE
REGION GIVEN THE MOISTURE AND DYNAMIC FORCING ASSOCIATED WITH THE
UPPER LOW HEADING OUR WAY.
TONIGHT...
UPPER LOW WILL BE OVER THE STATE. ISOLATED SHOWERS ARE LIKELY TO
CONTINUE THROUGHOUT THE NIGHT...BUT AS MENTIONED...BELIEVE THEY WILL
BE ISOLATED. BEST CHANCE WILL BE OVER THE CONTDVD REGION. SNOW
SHOWERS WILL OCCUR AT HIGHER ELEVATIONS WITH SOME LIGHT ACCUMS
LIKELY.
TOMORROW...
COOL NORTHEAST LLVL FLOW WILL PREVAIL OVER REGION. WITH UPPER LOW
OVERHEAD...ANTICIPATE SKIES WILL CLOUD UP RELATIVELY EARLY. ALTHOUGH
QUITE A FEW SHOWERS WILL LIKELY DEVELOP TOMORROW...OVERALL HEAVY
RAIN THREAT LOOKS LOW AT THIS TIME. IT WILL BE NOTICEABLY COOLER
TOMORROW ACROSS THE REGION AS HIGHS WILL ONLY BE IN THE 70S ALONG THE
I-25 CORRIDOR WITH TEMPS AOA 80F OVER THE FAR E PLAINS. 60S AND
70S ELSEWHERE ACROSS THE VALLEYS. IT WILL BE COOL ABOVE TREELINE
WITH HIGHS ONLY IN THE 30S AND 40S. SNOWSHOWERS WILL BE POSSIBLE.
OVERALL BEST CHANCE OF SHOWERS TOMORROW WILL BE ALONG THE EAST
FACING SLOPES OF THE EASTERN MTNS. /HODANISH
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 240 PM MDT WED AUG 27 2014
UPPER LOW FINALLY EXITS THE STATE EARLY FRI MORNING...WITH WEAK
CONVECTION ENDING FROM WEST TO EAST ACROSS THE REGION THU EVENING.
FLAT UPPER RIDGE THEN BUILDS ACROSS THE AREA FRI LEADING TO
MOSTLY DRY CONDITIONS AND SEASONABLY MILD TEMPS...ALTHOUGH SOME
ISOLATED WEAK TSRA MAY FORM OVER THE MTS IN THE AFTERNOON AS
RESIDUAL LOW LEVEL MOISTURE LINGERS. NEW WESTERN U.S. TROUGH
BEGINS TO MOVE ONSHORE DURING THE WEEKEND...WITH INCREASING W-SW
FLOW ACROSS COLORADO SAT INTO SUN. STILL A VERY SMALL CHANCE OF
SOME ISOLATED TSRA OVER THE HIGHER TERRAIN SAT AFTERNOON...THOUGH
AGAIN STORMS SHOULD BE HIGH BASED AND WEAK AS MOIST LAYER IS
FAIRLY SHALLOW. UPPER TROUGH THEN MOVES INTO THE NORTHERN HIGH
PLAINS SUN...PUSHING A COLD FRONT THROUGH COLORADO DURING THE
AFTERNOON. WITH NOSE OF THE UPPER JET MOVING ACROSS NORTHERN
COLORADO...STRONGEST UPWARD MOTION WILL LIKELY STAY NORTH OF THE
AREA...AND ONLY A SLIGHT CHANCE OF TSRA IS EXPECTED OVER THE
CENTRAL MTS AND FAR EASTERN PLAINS SUN AFTERNOON/EVENING. TEMPS
BOTH SAT AND SUN WILL CLIMB BACK ABOVE NORMAL...WITH WARMEST
READINGS JUST AHEAD OF THE COLD FRONT ON SUN.
WEAK LOW LEVEL MOISTURE RETURN DEVELOPS BEHIND THE FRONT ON
MON...THOUGH AIR MASS STAYS FAIRLY STABLE THROUGH THE DAY UNDER
SUBSIDENT UPPER FLOW BEHIND THE DEPARTING TROUGH. AS A
RESULT...SUSPECT ANY CONVECTION ON THE PLAINS WILL HAVE TO WAIT
FOR DEVELOPING WARM ADVECTIVE LIFT LATE MON NIGHT AS LOW LEVEL JET
DEVELOPS. ON TUE/WED...SHALLOW UPSLOPE FLOW WILL CONTINUE OVER THE
EASTERN MOUNTAINS AND PLAINS...THOUGH WITH FORCING STAYING RATHER
WEAK...SUSPECT CONVECTIVE COVERAGE WILL BE ONLY ISOLATED BOTH
DAYS. AFTER SOME MODEST COOLING ON MON...TEMPS BEGIN TO SLOWLY
CREEP BACK TO ABOVE SEASONAL LEVELS BY WED...ESPECIALLY OVER THE
PLAINS WERE A FEW 90S WILL REAPPEAR.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1112 PM MDT WED AUG 27 2014
THUNDERSTORMS HAVE PULLED OFF TO THE NORTHEAST OF THE KCOS AND
KPUB TERMINALS AND CURRENT TRENDS SUGGEST THAT IT WILL REMAIN DRY
WITH VFR CONDITIONS FOR THE REMAINDER OF THE NIGHT. WINDS WILL
REMAIN LIGHT AT KALS OVERNIGHT...WHILE KCOS AND KPUB CONTINUE TO
SEE SOME BREEZY NORTH WINDS GUSTING TO 25 KTS THROUGH 08-09Z.
ANOTHER ROUND OF ENERGY FROM THE UPPER LEVEL SYSTEM WILL MOVE
ACROSS THE AREA THURSDAY MORNING. THIS MAY RESULT IN AN EARLY
START TO -SHRA/-TSRA ON THURSDAY...WITH SHOWERS POSSIBLE IN THE
VCNTY OF KCOS BY 16Z. STRONGER THUNDERSTORMS WILL HOLD OFF UNTIL
AFTER 18Z. NORTH WINDS WILL INCREASE OFF THE PALMER DIVIDE
DURING THE LATE MORNING THROUGH EARLY AFTERNOON FOR KCOS AND KPUB
WITH ISOLATED INSTABILITY -TSRA MOVING SOUTHWARD ACROSS THE PLAINS
DURING THE AFTERNOON. BRIEF HEAVY RAIN WITH MAINLY VFR CIGS CAN BE
EXPECTED WITH THE STRONGER CELLS. KALS WILL ALSO SEE A CHANCE FOR
VCTS DURING THE AFTERNOON...THOUGH WINDS WILL REMAIN LIGHTER. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HODANISH
LONG TERM...PETERSEN
AVIATION...KT
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
534 PM CDT THU AUG 28 2014
.DISCUSSION...
230 PM CDT
VISIBLE IMAGERY THIS AFTERNOON SHOWS A MID/UPR LEVEL CLOUD DECK
LIFTING NORTHEAST ACROSS NORTHERN IL. REMNANTS FROM A MORNING
COMPLEX OF THUNDERSTORMS RESIDES OVER IOWA...WITH SOME CONVECTIVE
LOOK TO THE CLOUDS LINGERING INTO THIS AFTN. SFC TEMPS ACROSS THE
FORECAST AREA HAVE BEEN ABLE TO WARM INTO THE MID/UPR 70S. A FEW
POINTS SOUTH OF PONTIAC TO KANKAKEE HAVE PUSHED TO ARND 80 DEG...BUT
WITH THE LIGHT EASTERLY FLOW AT THE SFC SOME WEAK SUBSIDENCE HAS
BEEN NOTED WITH DEW POINTS BEING PUSHED INTO THE LOW 50S ALONG THE
LAKESHORE AND MID/UPR 50S INLAND.
THE MAIN CHALLENGE FOR THIS EVENING WILL FOCUS ON CONVECTIVE
CHANCES/COVERAGE...WHICH WILL CONTINUE THROUGH DAYBREAK FRI.
GUIDANCE HAS CONTINUED TO BACK OFF ON THE ARRIVAL OF PRECIP INTO THE
FORECAST AREA...WHICH SEEMS TO LINE UP RELATIVELY WELL WITH THE
CURRENT TRENDS. THE FRONTAL BOUNDARY WILL SLOWLY LIFT NORTH THIS
EVENING...BUT NOT EXPECTING MUCH IN THE WAY OF PRECIP UNTIL PERHAPS
AFT 04Z WITH A GRADUAL UPGLIDE OF PARCELS ALLOWS FOR MOISTENING.
SOME ELEVATED CONVECTION COULD BEGIN TO DEVELOP...ALTHOUGH NOT
EXPECTING MUCH COVERAGE OVERNIGHT. THE FOCUS FOR SLIGHTLY BETTER
PRECIP COVERAGE WILL REMAIN ALONG THE NORTHERN ROW OF COUNTIES IN
NORTHERN IL...HOWEVER CLOSER TO DAYBREAK FRI IT APPEARS SOME
PRECIP/CONVECTION COULD SAG SOUTHEAST AND CLIP NORTHEAST
IL/NORTHWEST IN BEFORE DISSIPATING.
WITH INCREASING CLOUD COVER TONIGHT...IT SHUD LIMIT HOW COOL TEMPS
BECOME. SO HAVE MADE ONLY MINOR ADJUSTMENTS TO THE TEMPS WITH
GENERALLY MID/UPR 60S FOR LOWS.
BEACHLER
FRIDAY AND FRIDAY NIGHT...
CLOSED UPPER LOW CURRENTLY NEAR THE COLORADO FRONT RANGE WILL SLOWLY
TRAVERSE EAST TOWARDS THE MID-MISSOURI VALLEY FRIDAY BECOMING AN
OPEN WAVE. AT THE SURFACE...BROAD AND WEAK SURFACE LOW WILL LIFT
INTO THE UPPER MIDWEST WHILE SOUTHWEST FLOW RAMPS UP THROUGH THE
COLUMN AS THE WARM FRONT LIFTS INTO THE CENTRAL GREAT LAKES. HEAT
AND HUMIDITY WILL MAKE A RETURN AS THIS OCCURS. H85 TEMPS WARMING TO
AROUND 18C WILL HELP SUPPORT MID/UPPER 80S DURING THE DAY
FRIDAY...AND SURFACE DEWPOINTS ARE PROGGED TO PUSH BACK INTO THE LOW
POSSIBLY MID 70S. THIS WILL RESULT IN MODERATE INSTABILITY
DEVELOPING DURING THE DAY...AND ONLY WEAKLY CAPPED DURING THE
AFTERNOON AS BROAD HEIGHT FALLS ASSOCIATED WITH THE UPPER WAVE START
TO OVERSPREAD THE AREA. THERE DOESNT SEEM TO BE MUCH FOCUS IN THE
LOWER LEVELS SO WOULD EXPECT ONLY SCATTERED THUNDERSTORM DEVELOPMENT
ACROSS THE REGION FRIDAY AFTERNOON/EVENING. UPPER WAVE BEGINS TO
MOVE INTO THE UPPER MIDWEST TOMORROW NIGHT AND BROAD WARM ADVECTION
OUT AHEAD DURING THE EVENING AND OVERNIGHT HOURS WILL HELP SUSTAIN
SOME CONVECTION LATE BUT WOULD EXPECT SOME NOCTURNAL DOWNTICK IN
ACTIVITY OVERNIGHT WITH THE LOW LEVEL JET FOCUSED WELL TO OUR NORTH.
GFS/NAM SEEM TO BE OVERDOING POPS MUCH OF THE DAY AND NIGHT
FRIDAY...AND OPTED TO LEAN CLOSER TO ECMWF THESE PERIODS.
THIS WEEKEND...
COLD FRONT WILL SWEEP ACROSS THE FORECAST AREA STARTING VERY EARLY
ON SATURDAY. WHILE NOT A FAVORABLE DIURNAL TIME...WE SHOULD STILL
HAVE SOME VERY MODEST INSTABILITY IN PLACE THAT WILL SUPPORT SOME
EARLY DAY THUNDERSTORMS ALONG THE FRONTAL BOUNDARY...WHICH WOULD BE
ABLE TO EXPAND IN COVERAGE AS THE DAY PROGRESSES AND THE BOUNDARY
LAYER WARMS. IN ADDITION...GUIDANCE SUGGESTS A SECOND SHORTWAVE
WILL WRAP INTO THE AREA THAT WILL PROVIDE ADDITIONAL BROAD SCALE
ASCENT. THE ECMWF IS ABOUT SIX HOURS SLOWER WITH THIS FEATURE
COMPARED TO THE NAM/GFS...WITH THE GEM A COMPROMISE...SO THERE
REMAINS SOME UNCERTAINTY IN TIMING. HIGH PRESSURE WILL BUILD IN
BEHIND THE FRONT SATURDAY NIGHT INTO SUNDAY AND WILL PROVIDE A
BRIEF RESPITE FROM THE ACTIVE WEATHER. THE ATMOSPHERE LOOKS TO
QUICKLY RELOAD HOWEVER WITH THERMAL RIDGE ONCE AGAIN STARTING TO
TILT BACK OVER THE AREA WITH H85 TEMPS AROUND 20C BY LATER IN THE
DAY SUNDAY.
NEXT WEEK...
AN ACTIVE PATTERN LOOKS TO PERSIST THROUGH AT LEAST THE MIDDLE OF
NEXT WEEK WITH A SERIES OF WAVES PUSHING ACROSS THE REGION BRINGING
CONTINUED PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS. ANOTHER
COLD FRONT WILL PUSH ACROSS THE AREA LATER ON MONDAY WITH THE
FRONTAL BOUNDARY STALLING JUST TO OUR SOUTH. THEREAFTER...THERE IS
CONSIDERABLE UNCERTAINTY ON HOW FAR NORTH THE BOUNDARY MAY LIFT
WITH THE BEST PRECIP CHANCES FOCUSED IN THE VICINITY OF THE
FRONT AS A SERIES OF UPPER LEVEL DISTURBANCES PUSH ACROSS THE
AREA. PWATS REMAIN JUICY ALONG THE FRONT...AROUND TWO INCHES...AND
GUIDANCE SUGGESTS THAT THERE COULD BE SEVERAL CONVECTIVE COMPLEXES
NEXT WEEK WITH A CONCERN FOR HEAVY RAIN AND FLOODING SHOULD THIS
PAN OUT.
DEUBELBEISS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* EAST WIND ARND 8-10KT THRU LATE AFTN...WINDS TURNING SE LATER
THIS EVENING.
* SHOWERS MOVING THROUGH BTW 00-03Z...WITH POTENTIAL TSRA AFT 09Z
THRU DAYBREAK FRI.
* MVFR IN -SHRA THIS EVENING
* WINDS CONTINUE TO TURN S FRI MORNING...WITH GUSTS DEVELOPING TO
20KT MIDDAY FRI.
BEACHLER/KMD
//DISCUSSION...UPDATED 18Z...
VISIBLE IMAGERY THIS AFTN SHOWS SOME THIN MID-DECK CLOUDS LIFTING
NORTHEAST ACROSS NORTHERN IL. MUCH THICKER CLOUDS AND SPOTTY
SHOWERS REMAINS OVER IOWA. SFC WINDS CONTINUE TO BE EASTERLY
ACROSS MUCH OF THE REGION...WITH A GRADUAL TURN TOWARDS SOUTHEAST
ACROSS CENTRAL IL/IN. A FRONTAL BOUNDARY WILL BEGIN TO LIFT NORTH
THIS EVENING...WITH INCREASING MOISTURE. THIS COULD AID IN SEEING
ISOLATED SHOWERS AND POSSIBLY A THUNDERSTORM LATER TONIGHT.
GUIDANCE CONTINUES TO LEAN TOWARDS THE 10-14Z FRI TIMEFRAME FOR
THE BEST COVERAGE OF SHOWERS AND ISO-TSRA DEVELOPING...BUT
CONFIDENCE REMAINS LOW WITH COVERAGE OF THUNDER. SO AT THIS TIME
HAVE HELD ONTO JUST A PROB30 GROUP. WINDS BEHIND THE FRONTAL
BOUNDARY WILL BEGIN TO TURN SOUTH AROUND DAYBREAK FRI...WITH
BETTER MIXING DEVELOPING BY LATE MORNING/EARLY AFTN. GUIDANCE
CONTINUES TO SUGGEST CONVETION COULD BEGIN TO DEVELOP YET AGAIN
LATE MORNING THROUGH THE AFTERNOON...HOWEVER FEEL THIS IS A BIT
OVERDONE.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN WIND DIR/SPEED AND TRENDS.
* MEDIUM HIGH CONFIDENCE IN -SHRA 0Z-3Z.
* MEDIUM-HIGH CONFIDENCE THAT CIGS/VSBY REMAIN VFR WITH SHOWERS.
* LOW-MEDIUM CONFIDENCE IN TIMING OF PRECIP AND COVERAGE AFTER FIRST
ROUND OF SHOWERS THIS EVENING.
* LOW CONFIDENCE IN THUNDER CHANCES/COVERAGE.
BEACHLER/KMD
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
* FRIDAY NIGHT...CHANCE OF TSRA.
* SATURDAY...TSRA LIKELY.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY AND TUESDAY...CHANCE OF TSRA.
* WEDNESDAY...DRY/VFR.
&&
.MARINE...
123 PM CDT
SURFACE HIGH PRESSURE OVER THE GREAT LAKES REGION THIS AFTERNOON
WILL DRIFT TO THE EAST TONIGHT IN THE WAKE OF A DEPARTING UPPER
TROUGH OVER NEW ENGLAND/QUEBEC...AND AHEAD OF ANOTHER SURFACE TROUGH
AND WEAK COLD FRONT STRETCHING FROM FAR NORTHWEST ONTARIO TO THE
CENTRAL PLAINS. WINDS ON LAKE MICHIGAN WILL SHIFT TO THE SOUTHEAST
AND EVENTUALLY SOUTH HEADING INTO FRIDAY...AS AN AREA OF SURFACE LOW
PRESSURE DEVELOPS ACROSS THE PLAINS AND LIFTS ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY. TIGHTENING OF THE PRESSURE GRADIENT
SOUTHEAST OF THE LOW TRACK WILL RESULT IN S-SE WINDS INCREASING INTO
THE 15-25 KT RANGE TONIGHT AND FRIDAY...GRADUALLY WEAKENING SATURDAY
AS THE LOW MOVES OFF TO THE NORTHEAST AND A WEAK COLD FRONT TRAILS
ACROSS THE LAKE FOLLOWED BY WEAK HIGH PRESSURE.
THIS COLD FRONT APPEARS TO DISSIPATE OR STALL ACROSS FAR SOUTHERN
LAKE MICHIGAN OR NORTHERN IL/IND LATE SATURDAY NIGHT OR EARLY SUNDAY
BEFORE DEVELOPING BACK TO THE NORTH AS A WARM FRONT SUNDAY NIGHT AS
ANOTHER AREA OF LOW PRESSURE DEVELOPS OVER THE PLAINS AND LIFTS
NORTHEAST INTO THE WESTERN/NORTHERN LAKES LATE SUNDAY NIGHT INTO
MONDAY. AGAIN...A TIGHTENING OF THE PRESSURE GRADIENT ALONG THE
SOUTHEAST PERIPHERY OF THE LOW TRACK IS EXPECTED WITH WINDS AGAIN
BECOMING SOUTHERLY INTO THE 15-25 KT RANGE ON MONDAY. ANOTHER
TRAILING COLD FRONT WILL PASS ACROSS THE LAKE MONDAY NIGHT...WITH
WEAK HIGH PRESSURE AND LIGHTER WINDS DEVELOPING TUESDAY.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
255 PM CDT Thu Aug 28 2014
.SHORT TERM...(This evening through Friday)
ISSUED AT 255 PM CDT THU AUG 28 2014
18z/1pm surface map shows warm front extending from northern
Missouri into western Kentucky. Aloft...vigorous upper-level low is
evident on water vapor imagery over eastern Colorado/western Kansas.
Large cluster of showers/storms associated with the low developed
along the front across Iowa last night and has since weakened as it
lifted northeastward into drier air over the Upper Midwest/Great
Lakes. Convection is still ongoing along outflow boundary from
eastern Iowa into northern Missouri: however, most of this will
remain W/NW of the KILX CWA late this afternoon into the early
evening. Meanwhile, scattered convection is firing further south
along the front across western Kentucky and this is expected to
develop further north into central Illinois over the next couple of
hours. HRRR has had a good handle on the convection and have
followed its solution closely for the immediate short-term. Have
therefore gone with scattered showers/thunder across all but the far
NE CWA around Champaign and Danville this afternoon into the
evening. Think convection will be diurnally driven and will
dissipate shortly after sunset.
As upper low slowly approaches from the west, corresponding
downstream ridging will help push the warm front northward tonight
into Friday. With strongest upper support remaining west of
Illinois through the day, think convection will once again only be
scattered in nature and primarily occur during peak heating. Have
therefore gone with a mostly dry forecast during the morning,
followed by chance PoPs during the afternoon. Best rain chances
will be focused closer to the frontal boundary across the northern
two-thirds of the CWA. High temperatures on Friday will be held
down a bit by clouds/precip, but will still rise well into the 80s,
with locations along/south of I-70 perhaps hitting the 90-degree
mark.
&&
.LONG TERM...(Friday night through Thursday)
ISSUED AT 255 PM CDT THU AUG 28 2014
Upper wave currently over the Rockies expected to slowly move out
and bring rain chances to the area, particularly Friday night and
Saturday as the upper trof moves through the Midwest. Keeping the
precip around on Saturday may result in slightly cooler temperatures
by the afternoon. Once again, the cold front associated with the
upper trof moves across the region, losing its distinct baroclinic
zone and becoming more diffuse as it slows considerably just to the
southeast near the Ohio River Valley. The remaining boundary will
keep pops around for the areas in the southeastern portions of the
state through the remains of the weekend until another larger trof
moves across the country bringing more widespread rain and thunder
for Sunday night into Monday. Signif differences between the ECMWF
and the GFS with the GFS being weaker with the boundary and leaving
a more stationary focus for prolonged showers...whereas the ECMWF is
more progressive and dries out the region on Tuesday. At this
point, the ECMWF builds a weak upper ridge into the Midwest and the
GFS stays more active.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1235 PM CDT THU AUG 28 2014
Warm front currently across southern Illinois will be the main
weather-maker over the next 24 hours. 17z radar imagery continues
to show dry conditions across the KILX CWA, although scattered
showers/thunder are beginning to develop further south across
western Kentucky/far southern Illinois. This is shown quite nicely
by the 3-hr HRRR forecast, which also shows widely scattered
thunder developing further north into west-central Illinois after
20/21z. Will continue to feature a period of VCTS this afternoon
into the early evening before any diurnal convection dissipates.
Even after the afternoon showers fade away, forecast soundings are
showing mid-level cloud deck remaining in place tonight. This
should mitigate any potential fog development, with the Rapid
Refresh showing visbys at or above 6sm through 10z. Winds will be
from the E/SE at less than 10kt this afternoon and tonight, then
will become S/SE by Friday morning as the warm front lifts
northward.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BARNES
LONG TERM...HJS
AVIATION...BARNES
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
105 PM CDT THU AUG 28 2014
.DISCUSSION...
310 AM CDT
MORE ACTIVE WEATHER WILL TRY TO RETURN TO THE AREA INTO THIS EVENING
FOR AT LEAST PART OF THE AREA FOLLOWING THE RATHER QUIET WEATHER
YESTERDAY. THE FORECAST WILL FOCUS ON TIMING AND COVERAGE OF
SHOWER/THUNDER CHANCES AS WELL AS TEMPERATURES...ESPECIALLY FRIDAY
WHEN THUNDERSTORMS COULD HINDER ANOTHER SUBSTANTIAL WARM UP. THE
MAIN FEATURE ON WATER VAPOR THIS MORNING IS AN UPPER LOW WHICH HAS
BEEN SLOWLY SPINNING EASTWARD ACROSS THE WESTERN U.S. THE LOW IS NOW
MAKING SLIGHTLY FASTER EASTWARD PROGRESS ACROSS COLORADO AND WYOMING
AND AMPLIFYING A RIDGE AHEAD OF IT INTO THE MID AND UPPER
MISSISSIPPI RIVER VALLEY. SEVERAL SMALLER SCALE SHORTWAVES ARE
MOVING NORTHEASTWARD AROUND THE BASE OF THE LOW AND LIFTING INTO
KANSAS AND NEBRASKA. LOOKING FURTHER NORTHWEST...A TROUGH AXIS
EXTENDS SOUTHWESTWARD FROM NORTHERN ALBERTA ACROSS CENTRAL BRITISH
COLUMBIA AND OVER THE PACIFIC WHILE A CLOSED UPPER IS DIGGING
SOUTHEASTWARD OFF THE SOUTHERN ALASKA COAST. AT THE SURFACE...HIGH
PRESSURE IS CENTERED OVER LAKE SUPERIOR WHILE A FRONTAL BOUNDARY
EXTENDS FROM THE MAINE COAST DOWN THE OHIO VALLEY AND BACK INTO THE
CENTRAL PLAINS. SURFACE LOW PRESSURE IS ORGANIZING ACROSS THE
CENTRAL AND SOUTHERN HIGH PLAINS IN CONJUNCTION WITH THE APPROACHING
UPPER LOW.
TODAY AND TONIGHT...THE UPPER RIDGE AXIS WILL BE CRESTING THE AREA
THIS MORNING AS THE ENTIRE RIDGE BROADENS INTO FRIDAY. THE SURFACE
HIGH WILL ACCELERATE EASTWARD AND BE CENTERED OVER THE LOWER ST.
LAWRENCE RIVER VALLEY BY FRIDAY. THE UPPER LOW WILL PUSH INTO THE
CENTRAL PLAINS WHILE THE ATTENDANT SURFACE LOW MOVES NORTHEASTWARD
INTO MINNESOTA TONIGHT. WARM ADVECTION AHEAD OF THE ADVANCING UPPER
TROUGH IS GENERATING SHOWERS AND THUNDERSTORMS ACROSS MUCH OF
NEBRASKA INTO SOUTHERN IOWA AND NORTHERN MISSOURI IN CONJUNCTION
WITH SEVERAL SHORTWAVES. THE WARM ADVECTION WILL SPREAD
NORTHEASTWARD WITH A SURFACE WARM FRONT ALSO MOVING NORTHEASTWARD
AND CROSSING THE LOCAL AREA TODAY. THE FOCUS OF THE ASCENT WILL BE
TO THE WEST AND NORTHWEST OF THE AREA THROUGH THE MORNING KEEPING
THE BULK OF IF NOT ALL OF THE SHOWER ACTIVITY OUT OF THE CWA.
HOWEVER...HAVE BEEN SEEING A FEW LIGHT SPRINKLES/SHOWERS ALONG AND
SOUTH OF THE SOUTHERN CWA BORDER THIS MORNING AS WELL LIKELY IN
CONJUNCTION WITH A SUBTLE MID LEVEL WAVE. EXPECT THESE TO SHIFT EAST
OF THE AREA THROUGH DAYBREAK. PRECIP CHANCES WILL INCREASE THIS
AFTERNOON HOWEVER...MAINLY ACROSS THE WESTERN HALF OF THE AREA AND
IT IS POSSIBLE THIS COULD BE A LITTLE FAST. A BETTER PUSH OF THETA-E
AND INSTABILITY MOVE ACROSS THIS EVENING...ESPECIALLY ACROSS
NORTHERN AREAS SO MAY SEE THE PEAK OF THE ACTIVITY DURING THIS TIME.
SOUTHERN AND EASTERN AREAS MAY END UP STAYING DRY FOR MUCH OF THIS
PERIOD. HIGHS TODAY WILL RANGE FROM THE UPPER 70S NORTH TO LOWER 80S
SOUTH WITH A FAIR AMOUNT OF CLOUD COVER EXPECTED.
FRIDAY...FRIDAY WILL BE A TRICKY FORECAST WITH THE POTENTIAL
FOR A NOTICEABLE WARM UP BUT ALSO A POTENTIAL TO HAVE THAT SPOILED
BY THUNDERSTORMS. THE WESTERN PERIPHERY OF THE MID LEVEL WARM AXIS
WILL BE OVER THE AREA WITH A SOUTH TO SOUTHWEST SURFACE WIND IN
PLACE. H85/H92 HIGH TEMP CLIMATOLOGY SHOWS STRONG SUPPORT FOR HIGHS
NEAR 90 WITH VALUES OF 18/23C. LATEST GUIDANCE SHOWS CONVECTION
DEVELOPING TO THE SOUTH OF THE AREA FRIDAY MORNING AND LIFTING
NORTHWARD ON THE WESTERN FLANK OF THE RIDGE AND CROSSING THE AREA
INTO THE AFTERNOON. TOUGH TO SAY IF THIS WILL BE THE CASE BUT THE
PATTERN IS CERTAINLY SUCH THAT THIS COULD OCCUR SO WILL CONTINUE
WITH POPS PRIMARILY FRIDAY AFTERNOON AND STICK WITH HIGHS IN THE MID
TO UPPER 80S FOR NOW.
FRIDAY NIGHT THROUGH MID NEXT WEEK...LARGER SCALE TROUGHING WILL BE
BUILDING INTO WESTERN NORTH AMERICA INTO SATURDAY WHICH WILL HELP
KICK THE CENTRAL PLAINS UPPER LOW NORTHEASTWARD. ANOTHER SURFACE LOW
WILL DEVELOP AND TRACK NORTHEASTWARD INTO WISCONSIN BY SATURDAY
MORNING. LATE FRIDAY NIGHT THROUGH SATURDAY MORNING WILL PROBABLY
END UP BEING THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS AS THIS
OCCURS. MORNING FRONTAL PASSAGE IS NOT ALL THAT FAVORABLE FOR SEVERE
WEATHER BUT DO EXPECT THAT SOME SORT OF LINE OR COMPLEX OF STORMS
WOULD AFFECT THE AREA...BRINGING HEAVY RAINFALL IF NOTHING ELSE.
HIGH PRESSURE RIDGING BUILDS IN NORTH OF THE AREA BEHIND THE
DEPARTING LOW. THE BIGGEST ISSUE WITH THIS HAS BEEN TIMING WITH THE
LATEST GUIDANCE FASTER THAN EARLIER RUNS KEEPING THE PRECIP CONFINED
TO SATURDAY MORNING. WILL ADJUST POPS TO BETTER FIT THIS BUT WILL
KEEP CHANCE POPS FOR SATURDAY AFTERNOON FOR NOW. H85 TEMPS COOL
BEHIND THE SYSTEM KEEPING HIGHS IN THE UPPER 70S AND LOWER 80S WITH
SLIGHTLY WARMER TEMPS SUNDAY. THE WESTERN TROUGH WILL AMPLIFY AS IT
MOVES INTO THE NORTHERN PLAINS TAKING A SURFACE LOW NORTHEAST FROM
THE NORTHERN PLAINS TO NORTHWESTERN ONTARIO LATER SUNDAY. TIMING
WILL ONCE AGAIN NEED TO BE BETTER ASSESSED BUT THIS SYSTEM WILL
BRING ANOTHER COOL FRONT ACROSS THE AREA SOME TIME MONDAY. A LOWER
AMPLITUDE UPPER FLOW BECOMES ESTABLISHED AS THE TROUGH DEPARTS WITH
HIGH PRESSURE BUILDING IN AT THE SURFACE. WIDESPREAD POP CHANCES
LOOK LOW INTO MIDWEEK BUT THE FAIRLY ZONAL FLOW WILL BE SUPPORTIVE
OF WEAK PASSING SHORTWAVES WHICH COULD TRIGGER SOME SPOTTY PRECIP AT
TIMES. HIGHS GENERALLY LOOK TO BE AROUND 80 BUT THE FLOW WILL LIKELY
BE WEAK ENOUGH TO SUPPORT LAKE COOLING AS LONG AS THE SURFACE HIGH
IS NEARBY.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* LIGHT EAST FLOW ARND 5-7KT THRU LATE AFTN...WINDS TURNING SE
WITH SPEEDS INCREASING TO ARND 10KT.
* POSSIBLE SHOWERS DEVELOPING AFT 03Z...WITH BETTER COVERAGE AND
POTENTIAL TSRA AFT 09Z THRU DAYBREAK FRI.
* WINDS CONTINUE TO TURN S FRI MORNING...WITH GUSTS DEVELOPING TO
20KT MIDDAY FRI.
BEACHLER
//DISCUSSION...UPDATED 18Z...
VISIBLE IMAGERY THIS AFTN SHOWS SOME THIN MID-DECK CLOUDS LIFTING
NORTHEAST ACROSS NORTHERN IL. MUCH THICKER CLOUDS AND SPOTTY
SHOWERS REMAINS OVER IOWA. SFC WINDS CONTINUE TO BE EASTERLY
ACROSS MUCH OF THE REGION...WITH A GRADUAL TURN TOWARDS SOUTHEAST
ACROSS CENTRAL IL/IN. A FRONTAL BOUNDARY WILL BEGIN TO LIFT NORTH
THIS EVENING...WITH INCREASING MOISTURE. THIS COULD AID IN SEEING
ISOLATED SHOWERS AND POSSIBLY A THUNDERSTORM LATER TONIGHT.
GUIDANCE CONTINUES TO LEAN TOWARDS THE 10-14Z FRI TIMEFRAME FOR
THE BEST COVERAGE OF SHOWERS AND ISO-TSRA DEVELOPING...BUT
CONFIDENCE REMAINS LOW WITH COVERAGE OF THUNDER. SO AT THIS TIME
HAVE HELD ONTO JUST A PROB30 GROUP. WINDS BEHIND THE FRONTAL
BOUNDARY WILL BEGIN TO TURN SOUTH AROUND DAYBREAK FRI...WITH
BETTER MIXING DEVELOPING BY LATE MORNING/EARLY AFTN. GUIDANCE
CONTINUES TO SUGGEST CONVETION COULD BEGIN TO DEVELOP YET AGAIN
LATE MORNING THROUGH THE AFTERNOON...HOWEVER FEEL THIS IS A BIT
OVERDONE.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN WIND DIR/SPEED AND TRENDS.
* HIGH CONFIDENCE IN ALL OTHER ELEMENTS THROUGH 04Z.
* MEDIUM CONFIDENCE IN TIMING OF PRECIP AND COVERAGE.
* LOW CONFIDENCE IN THUNDER CHANCES/COVERAGE.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
* FRIDAY NIGHT...CHANCE OF TSRA.
* SATURDAY...TSRA LIKELY.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY AND TUESDAY...CHANCE OF TSRA.
* WEDNESDAY...DRY/VFR.
&&
.MARINE...
300 AM...HIGH PRESSURE OVER THE LAKES REGION WILL MOVE EAST TODAY
AND TONIGHT REACHING NEW ENGLAND FRIDAY MORNING. EAST WINDS 10 TO
15 KTS WILL GRADUALLY TURN SOUTHEASTERLY THIS EVENING THEN MORE
SOUTHERLY OVERNIGHT INTO FRIDAY MORNING AND INCREASE. LOW PRESSURE
OVER THE WESTERN PLAINS WILL MOVE NORTHEAST TO MINNESOTA AND IOWA
BY FRIDAY MORNING THEN TURN NORTHEAST ACROSS THE NORTHERN LAKES
SATURDAY INTO SATURDAY EVENING. THE GRADIENT WILL TIGHTEN AHEAD OF
THIS LOW WITH 15-25KTS EXPECTED FRIDAY. THE GRADIENT WILL SLOWLY
WEAKEN FROM NORTH TO SOUTH FRIDAY NIGHT. A TRAILING COLD FRONT
FROM THIS LOW WILL THEN MOVE SOUTH ACROSS LAKE MICHIGAN SATURDAY
NIGHT INTO SUNDAY MORNING. THIS FRONT WILL THEN LIFT BACK NORTH AS
A WARM FRONT SUNDAY NIGHT AS STRONGER HIGH PRESSURE IS EXPECTED TO
MOVE ACROSS THE NORTHERN LAKES AND ONTARIO SUNDAY NIGHT AND
MONDAY. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1235 PM CDT Thu Aug 28 2014
.UPDATE...
ISSUED AT 1045 AM CDT THU AUG 28 2014
Morning surface analysis shows a warm front extending from
northern Missouri into the Ohio River Valley. A vigorous
upper-level low evident on water vapor imagery over western
Kansas/Nebraska has triggered a large complex of showers/thunder
north of the front across Iowa. This precip area is lifting
northeastward and will remain W/NW of the KILX CWA. Further
southeast along the front, only isolated showers are currently
observed across central Illinois. Showers/thunder will become more
numerous as the day progresses, but due to lack of strong upper
support, areal coverage will remain scattered in nature. Due to
clouds and precip, temperatures will be a bit cooler than in
previous days. Afternoon highs will range from around 80 far
northwest to the upper 80s south of I-70. Current forecast is
right on track, so no update is needed at this time.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 303 AM CDT THU AUG 28 2014
The location of the cold front appears to be just south of our
forecast area. It is forecast to return north as a warm front,
moving from SW to NE tonight. The unstable air mass extends well
north of the front all across our counties, as evidenced by the
isolated showers popping up early this morning across the northern
half of central IL. Added sprinkles to the northern counties for the
pre-dawn hours, and may need to extend the sprinkles after 12z east
toward CMI/DNV if the channel of precip continues. Otherwise,
overall thoughts on showers/storms are for a progression of chance
PoPs from west to east as the warm front begins to approach W-SW IL
in response to low pressure lifting from Nebraska into Minnesota.
The high res HRRR, ARW, and NMM along with the Canadian GEM all are
very scarce with coverage of storms over the next 12-24 hours, and
mainly in our far W-SW counties this afternoon. The 00z NAM, GFS,
and ECMWF all are a bit more aggressive, bringing precip as far east
as I-57 and LWV/Robinson. We kept the previous trends in the grids
of diurnally driven coverage, with higher chance PoPs in the SW half
of our forecast area this afternoon into early evening, then
trimming them back west later this evening/overnight. Confidence is
still low on precip coverage and timing based on very weak triggers
expected in our area northeast of the frontal boundary.
Sunshine will be filtered by mid-high clouds today, with highs in
the lower 80s north and some upper 80s S of Jacksonville to LWV.
Lows tonight will remain mainly in the lower 70s as the approaching
warm front keeps some cloud cover and higher dew points in our
area.
&&
.LONG TERM...(Friday through Wednesday)
ISSUED AT 303 AM CDT THU AUG 28 2014
Upper wave across the Rockies to make slow progress eastward
while dampening out Friday night over the Mississippi Valley.
Showers and storms Friday afternoon should be more scattered, with
a larger area of rain and storms coming in Friday night ahead of
the cold front. Have increased PoP`s to around 60% from I-55 west
by late Friday night and area-wide on Saturday.
The frontal boundary starts to become more diffuse Saturday night as
the upper wave flattens, and is difficult to discern by Sunday
morning. Have lingered the likely PoP`s across the southeast CWA
Saturday night as moisture continues to surge into the Ohio Valley,
and will keep high chance PoP`s going there into Sunday as well.
Further northwest, mainly dry conditions are on tap on Sunday.
Digging wave across the Rockies on Saturday night will be tracking
through the Mississippi Valley by Monday. Latest ECMWF draws some
cooler weather further south than the GFS, although not quite this
far south, as the west-east ridge across the lower tier of states
starts to strengthen again. Reasonable model agreement exists with
the associated cold front passing through on Monday, then hanging up
just south of I-70 as it becomes parallel to the upper flow. Showers
and storms to start moving back in Sunday night with the highest
chances on Monday. With the front hanging up, have lingered the
PoP`s across the southern CWA into Tuesday night, but did dry out
areas north as a small surface high drifts into the Great Lakes.
Rather muggy conditions to continue into early next week, with drier
air settling southward beginning Monday night behind the second
front.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1235 PM CDT THU AUG 28 2014
Warm front currently across southern Illinois will be the main
weather-maker over the next 24 hours. 17z radar imagery continues
to show dry conditions across the KILX CWA, although scattered
showers/thunder are beginning to develop further south across
western Kentucky/far southern Illinois. This is shown quite nicely
by the 3-hr HRRR forecast, which also shows widely scattered
thunder developing further north into west-central Illinois after
20/21z. Will continue to feature a period of VCTS this afternoon
into the early evening before any diurnal convection dissipates.
Even after the afternoon showers fade away, forecast soundings are
showing mid-level cloud deck remaining in place tonight. This
should mitigate any potential fog development, with the Rapid
Refresh showing visbys at or above 6sm through 10z. Winds will be
from the E/SE at less than 10kt this afternoon and tonight, then
will become S/SE by Friday morning as the warm front lifts
northward.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BARNES
SHORT TERM...SHIMON
LONG TERM...GEELHART
AVIATION...BARNES
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
904 PM CDT FRI AUG 29 2014
.SYNOPSIS...
ISSUED AT 1244 PM CDT FRI AUG 29 2014
A DEEP RICH MOISTURE PLUME CONTINUES TO FEED INTO EASTERN IOWA AND
MUCH OF THE UPPER MIDWEST. OUR CWA FELL WEST OF A FEW HEAVY RAIN
PRODUCING STORMS IN ILLINOIS EARLIER TODAY...AND UNDER A WEAK AREA
OF SUBSIDENCE THROUGH EARLY AFTERNOON. THIS HAS ALLOWED LOW LEVELS
TO HEAT UP UNINHIBITED. AS OF 1 PM...WIDESPREAD LOWER TO MID 80S ARE
FOUND OVER EASTERN IOWA AND WESTERN ILLINOIS...WITH DEWPOINTS IN THE
70 TO 73 RANGE. HIGHS TODAY SHOULD REACH THE MID TO UPPER 80S. CAPE
VALUES ESTIMATED BY SPC RAP AS OF 1 PM ARE 2000 TO 3000 OVER ALL OF
THE CWA. A VORTICITY MAXIMA IS LOCATED IN EASTERN KS...WITH A PVA
WING OF LIFT FOUND INTO CENTRAL MISSOURI. THIS IS ALREADY DEVELOPING
A LINE OF DEEP CONVECTION FROM NORTH CENTRAL TO SOUTH
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 1244 PM CDT FRI AUG 29 2014
THE VORT MAX TO THE SOUTHWEST WILL LIFT THROUGH IOWA THIS
EVENING...HELPING ORGANIZE STORMS AS THEY MOVE THROUGH THE CWA. FROM
LATE AFTERNOON THROUGH MID EVENING...THESE SHOULD IMPACT MUCH OF THE
CWA. A LACK OF SHEAR SHOULD DECREASE ANY WIDESPREAD SEVERE WEATHER
THREAT...BUT SOME ISOLATED WIND DAMAGE IS POSSIBLE THROUGH WET
MICROBURST ACTIVITY IN THE STRONGEST CELLS. OTHERWISE....THIS SHOULD
BE HEAVY RAIN PRODUCING LINE OF STORMS...WITH SOME BRIEF TRAINING
POSSIBLE. A WIDESPREAD RAIN OF 0.25 TO 0.75 IS EXPECTED...WITH
SWATHS OF 1 TO 2 INCHES. WE ARE LIKELY TO HANDLE THIS MINOR
FLOOD/URBAN RUNOFF THREAT WITH SPS PRODUCTS.
TONIGHT...STORMS SHOULD BECOME LESS NUMEROUS...AND POSSIBLY END
FULLY. HOWEVER...WITH THE PARENT VORT MOVING BY WITH AMPLE
MOISTURE...WE WILL LEAVE POPS GOING THROUGH THE NIGHT.
SATURDAY...MODELS BRING ANOTHER QUICK SHOT OF ENERGY THROUGH WHILE
MOISTURE IS DEPARTING. THIS MAY BRING SOME SHOWERS AND STORMS TO
ROUGHLY THE EAST HALF...BUT SHOULD SUBSIDENCE BECOME MORE CONFIDENT
BEHIND TONIGHTS STORMS...WE MAY BE DRY ALL DAY SATURDAY.
TEMPERATURES LOOK MILD TONIGHT...IN THE UPPER 60S...WHILE SATURDAY
SHOULD SEE A DRY AFTERNOON REBOUND TO THE UPPER 70S TO LOWER 80S.
CLOUDS WHILE THICK IN THE MORNING SHOULD BECOME SCATTERED BY MID
DAY.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 1244 PM CDT FRI AUG 29 2014
THE MAIN FORECAST CONCERN IN THE LONG TERM PERIOD IS STORM
COVERAGE/RAINFALL AMOUNTS/SEVERE POTENTIAL WITH THE ARRIVAL OF THE
NEXT SYSTEM SUNDAY NIGHT INTO MONDAY.
EARLY IN THE PERIOD...HAVE MAINTAINED DRY FORECAST FOR SATURDAY
NIGHT THROUGH SUNDAY AFTERNOON. MEDIUM RANGE MODELS HAVE CONTINUED
A GENERAL TREND OF SLOWING THE ARRIVAL OF THE NEXT FRONTAL
BOUNDARY AND UPPER LEVEL TROUGH. HAVE REDUCED AND TRIMMED POPS
BACK TO THE NORTHWEST FOR SUNDAY EVENING...AND ADDITIONAL
ADJUSTMENTS MAY BE NEEDED OVER THE NEXT COUPLE OF DAYS. THE MAIN
WINDOW OF SHOWERS/STORMS IS NOW EXPECTED LATE SUNDAY NIGHT INTO
MONDAY MORNING. THE LATER TIMING MEANS FAVORABLE SEVERE WEATHER
PARAMETERS WILL LIKELY STAY WEST OF THE FORECAST AREA...WITH THE
MOST LIKELY SCENARIO BEING A DECAYING MCS AND POSSIBLY SOME
LOCALLY HEAVY RAIN. STORMS MAY CONTINUE INTO THE AFTERNOON...AND
POSSIBLY MONDAY NIGHT DEPENDING ON HOW FAR SOUTH THE FRONT PUSHES.
LOOKING AHEAD...CONFIDENCE IN FORECAST DETAILS IS LOWER AS THE
OPERATIONAL GFS AND EURO VACILLATE BETWEEN WEAK TROUGHING AND
ZONAL FLOW ACROSS THE REGION. TIMING AND LOCATION OF THE VARIOUS
WEAK IMPULSES IS CHALLENGING AND RIGHT NOW THERE IS NO REASON TO
VARY FROM THE CONSENSUS BLEND POPS...ESSENTIALLY SLIGHT TO LOW
CHANCE IN EVERY PERIOD THROUGH FRIDAY. TEMPERATURES ARE EXPECTED
TO BE NEAR TO SLIGHT ABOVE NORMAL THROUGH THE PERIOD...WITH
AFTERNOON HIGHS GENERALLY IN THE 8OS AND LOWS IN THE 60S TO LOWER 70S.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 900 PM CDT FRI AUG 29 2014
UPPER LOW TO PASS ACROSS THE REGION THE NEXT 12-18 HOURS WITH LOTS
OF CLOUDS AND AREAS OF SHOWERS AND STORMS. MOSTLY VFR CONDITIONS
ALL TERMINALS WITH BRIEF MVFR CONDITIONS NEXT 6+ HOURS POSSIBLE IN
ANY STORMS THAT ARE HANDLED AS A TEMPO GROUP UNTIL LATE EVENING
WITH VICINITY WORDING OVERNIGHT. SKIES TO BECOME FAIR BY MID TO
LATE MORNING WITH VFR CONDITIONS THROUGH AT LEAST 31/00Z. LIGHT
SOUTH WINDS TO BECOME WESTERLY AT 5 TO 10 KTS ON SATURDAY.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...ERVIN
AVIATION...NICHOLS
AREA FORECAST DISCUSSION
NWS DES MOINES IA
316 PM CDT THU AUG 28 2014
.SHORT TERM /TONIGHT/...
ISSUED AT 315 PM CDT THU AUG 28 2014
PRIMARY FORECAST QUESTION FOR TONIGHT IS COVERAGE AND TIMING OF
PRECIPITATION. RECENT RADAR TRENDS AND HIGH RESOLUTION MODELS SUCH
AS THE WRF AND HRRR HAVE INDICATED A SIGNIFICANT DECREASING TREND IN
PRECIP COVERAGE LATE THIS AFTERNOON AND EVENING...HOWEVER MOST SHORT
RANGE MODELS CONTINUE TO FORECAST AN INCREASE ONCE AGAIN AFTER DARK
TONIGHT. THIS IS CONSISTENT WITH THE SYNOPTIC SCENARIO CHARACTERIZED
BY BROAD UPPER LEVEL DIFFLUENCE OVER A SATURATED ATMOSPHERE. HAVE
CARRIED GENERALLY CHANCE POPS/SCATTERED WORDING THROUGH THE NIGHT
GIVEN THE SUPPORT FOR REDEVELOPMENT...BUT HAVE LITTLE CONFIDENCE IN
DETAILS OF TIMING AND LOCATION THUS THE POP FORECAST IS BROADBRUSHED
FOR NOW. OTHERWISE LITTLE CHANGE WAS MADE TO THE ONGOING FORECAST.
.LONG TERM /FRIDAY THROUGH THURSDAY/...
ISSUED AT 315 PM CDT THU AUG 28 2014
WITH UPPER LEVEL TROUGH STILL WEST OF THE AREA THROUGH EARLY
SATURDAY MORNING...LIKELY TO SEE SOME ADDITIONAL ROUNDS OF
THUNDERSTORMS ACROSS THE REGION THROUGH THAT TIME. OVER THE NEXT 24
TO 36 HOURS...THE HIGHEST PRECIPITABLE WATER VALUES WILL GRADUALLY
SHIFT EAST OF THE REGION AS H850 MOISTURE TRANSPORT BEGINS TO SHIFT
EAST AS WELL. BY 12Z FRIDAY...ONE ADDITIONAL WAVE...THE KICKER
WAVE...WILL BE LOCATED OVER SOUTHEAST KS/WESTERN MO. THIS SHOULD
LIFT NORTHEAST DURING THE NEXT 24 HOURS RESULTING IN INCREASING LIFT
OVER THE REGION FRIDAY AFTERNOON AND EVENING. IN COMBINATION WITH
THAT A COLD FRONT AND UPPER LEVEL LOW OVER SOUTHERN CANADA WILL
DRIFT SOUTHEAST AND ALSO AID IN DISPLACING THE TROUGH ACROSS THE
GREAT PLAINS. THROUGH THE PERIOD FRIDAY INTO EARLY SATURDAY...
ANOTHER HALF INCH TO INCH OF RAINFALL IS LIKELY TO FALL WITH THE
HEAVIER TOTALS OVER THE NORTH AND NORTHEAST PORTION OF THE FORECAST
AREA. WITH RAINFALL RATES SLOWING DOWN...FLASH FLOODING IS PROBABLY
NO LONGER A THREAT...BUT SATURATED GROUND MAY LEAD TO SOME MINOR
RUNOFF PROBLEMS AT TIMES INCLUDING SOME PONDING OF WATER AND MINOR
STREET FLOODING IN AREAS OF POOR DRAINAGE. TEMPERATURES TOMORROW
WILL LIKELY WARM A BIT IN THE SOUTHEAST IN THE LOWER 80S...AHEAD OF
THE WAVE WITH WARM AIR ADVECTION AND SOME POTENTIAL BREAKS IN THE
CLOUD COVER IN THE SOUTHEAST. AS THE COOL FRONT MOVES EAST PRECIP
CHANCES SHOULD END ACROSS THE REGION SATURDAY MORNING WITH SOME
SUNSHINE RETURNING TO THE AREA BY MORNING. HIGHS WILL BE SLIGHTLY
WARMER...BUT STILL WITHIN THE A FEW DEGREES OF HIGHS OF FRIDAY WITH
MORE SUNSHINE...BUT SOME SLIGHT COOL AIR ADVECTION. MODELS IN
GENERAL AGREEMENT WITH THE NEXT STRONG WAVE EXPECTED TO ARRIVE BY
SUNDAY AFTERNOON....WITH A RATHER WARM DAY AHEAD AS H850 RISE TO
NEAR 20C BY AFTERNOON. THE GFS SHOWS THAT PWATS WILL ONCE AGAIN RISE
TO NEAR OR SLIGHTLY ABOVE 2 INCHES ALONG THE BOUNDARY AS IT MOVES
INTO WESTERN IOWA BY 00Z. UPPER LEVEL WIND FIELDS AGAIN SHOW A
MODEST INCREASE AS A MODESTLY STRONG WAVE APPROACHES FROM THE
SOUTHWEST WITH 0-6KM BULK SHEAR OVER 40 KTS ACROSS THE AREA. THIS
SHOULD BE ENOUGH TO PROMOTE SEVERE STORMS DURING THE LATE AFTERNOON
AND EVENING HOURS. ANOTHER ROUND OF STORMS WITH OVER AN INCH OF RAIN
IN SOME OF THE HEAVIER STORMS IS EXPECTED. FINALLY...THE REMAINDER
OF THE FORECAST SUGGESTS THAT A BREAK FROM THE ACTIVE WEATHER WILL
RETURN FROM LATER ON MONDAY THROUGH WEDNESDAY...WITH SOME POTENTIAL
FOR A QUICK MOVING STORM AGAIN BY THURSDAY.
&&
.AVIATION...28/18Z
ISSUED AT 1220 PM CDT THU AUG 28 2014
MORNING SHOWERS AND THUNDERSTORMS ARE CLEARING THE AREA TO THE
NORTHEAST...BUT WILL LINGER ESPECIALLY AT MCW/OTM INTO THIS
AFTERNOON. BR AND IFR/LIFR CIGS ARE SIMILARLY TRYING TO CLEAR OUT
AND SHOULD EXIT FOD/DSM WITHIN THE NEXT HOUR OR TWO...BUT AGAIN AT
MCW/OTM MAY PERSIST LONGER AND IT IS DIFFICULT TO TELL WHETHER
THEY WILL LIFT AT ALL AT MCW TODAY. TONIGHT EXPECT MORE SHRA/TSRA
DEVELOPMENT ESPECIALLY AT FOD/MCW...ALONG WITH MORE LOWER CIGS AND
BR IN MOST AREAS AFTER MIDNIGHT. HAVE TAKEN A SHOT AT TRENDING
THIS WAY IN THE 18Z TAFS...BUT DETAILS WILL NEED TO BE REFINED
THIS EVENING/TONIGHT.
&&
.HYDROLOGY...
ISSUED AT 315 PM CDT THU AUG 28 2014
SEVERAL ADDITIONAL EPISODES OF RAIN ARE EXPECTED THROUGH SATURDAY
MORNING AND AGAIN ANOTHER SUNDAY AFTERNOON THROUGH MONDAY MORNING.
AT THIS TIME EXPECTED RAINFALL AMOUNTS THROUGH SATURDAY MORNING WITH
EACH EVENT SHOULD BE LIGHT TO MODERATE. THIS WILL LIMIT THE LIKELIHOOD
OF FLASH FLOODING BUT STILL HAVE SOME EFFECT ON RISES ON SMALL STREAM
AND AREA RIVERS. THERE IS A GREATER RISK OF MORE SUBSTANTIAL RAINFALL
OVER PORTIONS OF THE FORECAST AREA SUNDAY EVENING. THIS TIME PERIOD
WILL BE MONITORED FOR BOTH SHORT TERM FLOODING AND RIVER FLOODING
OVER THE UPCOMING HOLIDAY WEEKEND.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...LEE
LONG TERM...REV
AVIATION...LEE
HYDROLOGY...REV
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1207 AM CDT THU AUG 28 2014
.UPDATE...
ISSUED AT 939 PM CDT WED AUG 27 2014
NO CHANGES TO EXISTING FLASH FLOOD WATCH HEADLINE. CURRENT NE/KS
MCS UPSTREAM IS EMBEDDED WITHIN A BROAD AREA OF WEAK/MODERATE
KINEMATIC AND THERMODYNAMIC FORCING AHEAD OF ROCKIES LONG WAVE
TROUGH IN AIRMASS VERY FAVORABLE FOR HEAVY EFFICIENT RAINFALL.
STRONGEST CONVECTION COINCIDES NICELY WITH 01Z RAP PRECIP
POTENTIAL PLACEMENT MAX AND THIS CROSSES MO RIVER INTO WRN
FORECAST AREA 09-12Z WITH MEAN WIND...THUS SLOWED POP ADVANCEMENT
SOMEWHAT IN EVENING UPDATE. 1-2KM MOISTURE FLOW AND ASSOCIATED
TRANSPORT IS NOT OVERLY STRONG...BUT VEERS INTO WRN IA BY
DAYBREAK. WITH PWS STILL IN EXCESS OF 2 INCHES...K INDICES AROUND
40...AND WARM CLOUD DEPTHS 4.2KM...ANY STRONGER CONVECTION COULD
CERTAINLY STILL PRODUCE EXCESSIVE RAINS.
&&
.SHORT TERM /TONIGHT/...
ISSUED AT 345 PM CDT WED AUG 27 2014
TIMING AND LOCATION OF HEAVY RAIN WAS FORECAST CONCERN TONIGHT
WITH ANOTHER ROUND OF CONVECTION ANTICIPATED TO DEVELOP OVERNIGHT.
LEANED TOWARD A BLEND OF THE ECMWF/NAM12 AND THE LATEST HRRR/HOPWRF/4.0KM
SPCWRF FOR TIMING OF THE PRECIP. BIGGEST CHANGE WAS SLOWED DOWN
THE ONSET ROUGHLY 2 TO 4 HOURS FROM PREVIOUS FORECAST PACKAGE AND
STILL MAY BE TOO QUICK FOR REDEVELOP TONIGHT.
LLJ INCREASES OVER SOUTH-CENTRAL NEBRASKA/NORTHERN KANSAS WITH THE
NOSE NUDGING INTO SOUTHWEST TO WESTERN PORTIONS OF THE IOWA PAST 06Z
THURSDAY. THE BEST THETA-E ADVECTION SURGES ACROSS SOUTHWEST IOWA
NORTHEASTWARD INTO NORTH-CENTRAL IOWA BY THURSDAY MORNING AND THE
BEST MOISTURE CONVERGENCE LOOKS TO BE B/T HIGHWAY 20 TO NEAR I-80
CORRIDORS BUT CERTAINLY NOT LIMITED TO THOSE LOCATIONS. PRECIPITABLE
WATER VALUES IN THE 2 TO 2.25 INCH RANGE OVER WESTERN IOWA AND WARM
LAYER CLOUD DEPTHS AROUND 13KFT...SO ANTICIPATING SOME EFFICIENT
RAIN PRODUCERS OVERNIGHT. MOISTURE TRANSPORT ERUPTS WITH THE LLJ
INCREASING OVERNIGHT AND WITH WEAK CORFIDI VECTORS...SUGGESTING
TRAINING POTENTIAL AS WELL. LEANED TOWARD ISSUING A FLASH FLOOD
WATCH BASED ON THE LATEST HIRES MODEL TRENDS AND 27.12Z NAM/ECMWF
CONVECTIVE/QPF TRENDS. IT WILL NOT TAKE MUCH TO GET SOME FLASH FLOOD
ISSUES OVER THE WESTERN PORTIONS OF THE FORECAST BY EARLY THURSDAY
MORNING. MAY NEED TO EXTEND/EXPAND THE WATCH FURTHER NORTH...BUT FFG
IS A BIT HIGHER ALONG THE MINNESOTA AND HAD LESSER CONFIDENCE WITH
FLASH FLOOD POTENTIAL IN THIS AREA.
.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
ISSUED AT 345 PM CDT WED AUG 27 2014
MAIN CONCERNS WILL BE RAINFALL AND THREAT FOR ANY FLOODING THROUGH
THE EXTENDED PERIOD. ONGOING CONVECTION SHOULD BE DIMINISHING
THROUGH THE DAY...BUT MODERATE RAINFALL IS STILL EXPECTED AS THE
BOUNDARY LIFTS TO THE NORTHEAST AND MCS FOLLOWS AND LIFTS INTO
SOUTHERN MN. MODELS ARE NOW SPLIT ON LOCATION OF HEAVIER RAINFALL
THROUGH TOMORROW...BUT CONSENSUS IS FOR A SLIGHTLY SLOWER EVOLUTION
AND FARTHER SOUTH AND WEST MAX OVERALL...WHICH PUTS THE RAINFALL FOR
THURSDAY OVER NORTHERN IOWA A BIT LONGER INTO THE MORNING AND EARLY
AFTERNOON HOURS PRIOR TO CHANCES DIMINISHING DURING THE AFTERNOON.
EURO/GFS HAVE COME INTO LINE FARTHER SOUTH WITH TODAYS 12Z PACKAGE.
ISENTROPIC LIFT AND MOISTURE TRANSPORT FOCUSING BEST LIFT OVER
WEST CENTRAL/NORTHWEST IOWA TO START THE PERIOD AT 12Z THURSDAY
AND GRADUALLY SHIFTING THE BEST LIFT TOWARD THE IA/MN BORDER BY
18Z. SOMEWHAT COMPLICATED SCENARIO BOTH TONIGHT AND THURSDAY AS
UPPER LEVEL RIDGE AXIS HOLDING STRONG...AND EFFECTIVELY WILL
CREATE A STRONGER BOUNDARY ALOFT AS STRONG PUSH OF THETAE ADVECTION
ADVANCES NORTH...THEN HITTING A SLOWLY RETREATING RIDGE AXIS. THIS
IS PART OF THE REASON FOR THE MORE SOUTHERN FOCUS AS MASS CONVERGENCE
INCREASES OVERNIGHT/THURSDAY MORNING ACROSS THE NORTH. ONCE THE
MAIN FORCING LIFTS NORTHEAST WITH THE FIRST STRONG PUSH OF WARM
AIR...TWO MORE WEAK WAVES WILL LIFT NORTHEAST INTO THE AFTERNOON
AND OVERNIGHT HOURS WITH ADDITIONAL LIGHT TO MODERATE RAINFALL
EXPECTED THROUGH FRIDAY NIGHT. THE HIGHEST RAINFALL TOTALS WILL
OCCUR THROUGH THURSDAY...BUT ANY ADDITIONAL RAINFALL WILL ADD TO
THE POTENTIAL FOR A RISK OF SOME FLOODING...EITHER RIVER OR
ISOLATED FLASH FLOODING. WILL BE MONITORING CLOSELY OVER THE NEXT
COUPLE OF DAYS AFTER TONIGHTS EVENT UNFOLDS. WITH CLOUDS AND
RAINFALL EXPECTED...HIGHS WILL BE HELD BACK TO NEAR 70 NORTH TO
THE LOWER 80S ACROSS THE SOUTH. RAIN CHANCES REMAIN HIGH THROUGH
FRIDAY NIGHT WITH A MUCH NEEDED BREAK ARRIVING FOR MOST OF
SATURDAY AND A PART OF SUNDAY. MODELS DIFFER ON DETAILS AGAIN BY
SUNDAY...WITH EURO BEING SLIGHTLY SLOWER IN ARRIVAL OF RATHER
ROBUST LATE SUMMER SYSTEM. ANOTHER PERIOD OF MODERATE TO POSSIBLY
HEAVY RAIN COULD OCCUR SUNDAY EVENING WITH THE PASSAGE OF THE NEXT
SYSTEM. ADDITIONALLY...ALONG WITH A SHORT WAVE ARRIVING IN THE
EARLY EVENING...UPPER LEVEL WIND FIELDS AND INSTABILITY INCREASE
ENOUGH TO BE CONCERNED WITH MORE ORGANIZED SEVERE WEATHER LATE
SUNDAY AFTERNOON AND EVENING. THE MORE PROGRESSIVE NATURE OF THE
SYSTEM SHOULD RESULT IN A QUICKER EXIT...WITH A RETURN TO DRIER
WEATHER FOR TUESDAY AND WEDNESDAY. FOR NOW WILL TREND POPS DOWN ON
TUESDAY...WITH A CHANCE WE COULD BE TOTALLY DRY BY THAT TIME.
HIGHS THROUGH MOST OF THE PERIOD WILL BE IN THE 70S TO LOWER 80S.
&&
.AVIATION...28/06Z
ISSUED AT 1207 AM CDT THU AUG 28 2014
LITTLE CHANGE FROM PREVIOUS THINKING /00Z/ WITH PRIMARY CONCERN CATEGORY
CHANGES DRIVEN BY EXPANDING CONVECTION OVERNIGHT. ALTHOUGH MVFR
CIGS HAVE EXPANDED SOMEWHAT THEY HAVE YET TO REACH TAF SITES WHICH
REMAIN VFR AT 06Z. EXPECT CIGS AND VSBYS TO LOWER TO MVFR AND
POSSIBLY IFR WITH PRECIP ONSET BY EARLY THIS MORNING AS IT CROSSES
THE MO RIVER INTO IA...AND COULD LAST FOR A PROLONGED PERIOD.
CONDITIONS MAY RETURN TO VFR BY THU AFTERNOON...BUT POTENTIAL FOR
AT LEAST LIGHT PRECIP WILL LINGER THROUGH THE ENTIRE PERIOD. NRN
SITES /KMCW/ MAY ALSO EXPERIENCE A RETURN TO LOWER CIGS/VSBYS
DURING THE EVENING.
&&
.HYDROLOGY...
ISSUED AT 345 PM CDT WED AUG 27 2014
RAINFALL RATES OF 1 TO 2 INCHES PER HOUR WITH LOCALLY HIGHER
RATES ARE POSSIBLE OVER WEST-CENTRAL TO SOUTHWEST IOWA LATE
TONIGHT INTO THURSDAY. 1-HR FFG IS AROUND AN INCH AND 3-HR FFG IS
LESS THAN 2 INCHES IN MOST PLACES...SO GROUND IS PRIMED FOR FLASH
FLOODING OVERNIGHT. WITH THE WIDESPREAD QPF AMOUNTS OF 1 TO 2
INCHES FROM 09Z THURSDAY TO 00Z FRIDAY...THE RACCOON AND SMALLER
RIVER BASINS MAY SEE RISES BY THURSDAY INTO FRIDAY AND ATTM MAINLY
REACHING ACTION STAGE OR MINOR FLOOD STAGE.
HYDROLOGY CONCERNS REMAIN ACROSS THE AREA THROUGH MONDAY. WITH
ADDITIONAL RAIN EXPECTED THURSDAY NIGHT THROUGH EARLY SATURDAY
MORNING...AND ANOTHER ROUND OF POSSIBLE MODERATE TO HEAVY RAINFALL
OVER PORTIONS OF THE AREA SUNDAY AFTERNOON/EVENING...ADDITIONAL
SMALLER STREAM AND RIVER RESPONSES ARE LIKELY. ITS TOO EARLY TO
GAUGE THE OVERALL MAGNITUDE OF THE IMPACTS...WITH RIVER LEVELS
CURRENTLY RUNNING WELL BELOW FLOOD STAGE AT MOST LOCATIONS. AFTER
TOMORROW...THERE WILL BE BETTER CLARIFICATION ON THE IMPACTS
EXPECTED OVER THE WEEKEND.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM 3 AM CDT EARLY THIS MORNING THROUGH THIS
MORNING FOR ADAIR-ADAMS-AUDUBON-CALHOUN-CARROLL-CASS-CLARKE-
CRAWFORD-DALLAS-DECATUR-GREENE-GUTHRIE-MADISON-RINGGOLD-SAC-
TAYLOR-UNION.
&&
$$
UPDATE...SMALL
SHORT TERM...PODRAZIK
LONG TERM...REV
AVIATION...SMALL
HYDROLOGY...PODRAZIK/REV
AREA FORECAST DISCUSSION
NWS WICHITA KS
629 PM CDT FRI AUG 29 2014
...UPDATED FOR 00Z AVIATION DISCUSSION...
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 256 PM CDT FRI AUG 29 2014
MODERATE INSTABILITY UNDER UPPER TROF ACROSS CENTRAL AND EASTERN
KANSAS WILL SUPPORT SCATTERED DIURNAL CONVECTION LATE THIS
AFTERNOON/EVENING. VISIBLE SATELLITE SHOWED AGITATED CU FIELD
JUST WEST OF WICHITA METRO WITH CONVECTIVE DEVELOPMENT IN RENO
COUNTY SINCE 1930Z. THE RUC AND HRRR WHERE SUGGESTIVE OF CONVECTIVE
DEVELOPMENT ALONG/JUST WEST OF THE TURNPIKE CORRIDOR BEFORE
SHIFTING CHANCES FURTHER EAST THRU THE EVENING. THIS IS HANDLED
FAIRLY WELL IN THE GOING FORECAST. OTHERWISE THE WEEKEND LOOKS TO
BEGIN ON A WARM BUT DRY NOTE FOR MOST OF THE AREA ON SATURDAY AS
THE UPPER TROF MOVES SLOWLY EAST AWAY FROM THE AREA. HOWEVER THE
LATTER PART OF THE HOLIDAY WEEKEND LOOKS A BIT MORE VOLATILE AS
INCREASING WESTERLY FLOW ALOFT OVER THE PACIFIC MOVES ACROSS THE
WESTERN CONUS WITH THE DEVELOPMENT OF A PROGRESSIVE UPPER TROF
MOVING FROM THE CENTRAL/NORTHERN ROCKIES ACROSS THE PLAINS BY LATE
SUNDAY. A MODERATE TO VERY UNSTABLE AIRMASS WILL DEVELOP AHEAD OF
THE ASSOCIATED SURFACE DRYLINE AND COLD FRONT LATE SUNDAY
AFTERNOON AND EVENING ACROSS CENTRAL KANSAS. DIURNAL SURFACE BASED
CONVECTION WILL LIKELY BE SUPPRESSED BY A STOUT CAPPING INVERSION
UNTIL VERY LATE IN THE AFTERNOON OR PERHAPS EARLY EVENING ON
SUNDAY. HOWEVER THE FORCING FOR ASCENT SHOULD BE MORE THAN
SUFFICIENT ALONG THE FRONT WITH DEEP LAYER SHEAR SUPPORTIVE OF A
SEVERE CONVECTIVE EPISODE SUNDAY EVENING INTO PART OF SUNDAY
NIGHT. WHILE THIS COMPLEX WILL LIKELY EXIT STAGE RIGHT BY MONDAY
MORNING...THE SURFACE FRONT IS EXPECTED TO LAY OUT ACROSS SOUTH
CENTRAL INTO EASTERN KANSAS DURING THE DAY. THE COMBINATION OF
DIURNAL HEATING AND A TRAILING SHORTWAVE ALOFT MIGRATING EAST
ACROSS THE AREA SHOULD RESULT IN RENEWED CONVECTION BY LATE
MONDAY. MODERATE TO STRONG INSTABILITY AND SHEAR COULD ALSO GIVE
RISE TO ANOTHER ROUND OF SEVERE STORMS.
DARMOFAL
.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 256 PM CDT FRI AUG 29 2014
PLAN TO MAKE LITTLE CHANGES TO THE OUTER PERIODS OF THE
FORECAST...WITH CHANCES FOR CONVECTION WANING AND TEMPERATURES
GRADUALLY WARMING WITH GEOPOTENTIAL HEIGHT RISES EXPECTED AS
THE UPPER RIDGE BUILDS IN ACROSS THE AREA AGAIN DURING THE WEEK.
KED
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 629 PM CDT FRI AUG 29 2014
AS OF THIS ISSUANCE SHOWERS WITH POSSIBLE THUNDER ARE IMPACTING
THE KICT TERMINAL. THESE ARE NOT EXPECTED TO BE LONG LASTING...BUT
COULD IMPACT THE TERMINAL AND VICINITY FOR THE NEXT COUPLE OF
HOURS. KCNU COULD ALSO SEE SCATTERED THUNDERSTORMS THROUGH THE
EVENING/EARLY OVERNIGHT HOURS AS THE UPPER WAVE MOVES ACROSS THE
AREA. WINDS WILL BECOME LIGHT ACROSS THE AREA WITH VARIABLE WINDS
AT KHUT/KICT AND WEST TO NORTHWEST WINDS AT KRSL/KSLN BEFORE
BECOMING SOUTHERLY DURING THE DAY SATURDAY AT THE LATER TWO SITES.
VFR EXPECTED THROUGH THE FORECAST EXCEPT FOR BRIEF PERIODS OF
THUNDERSTORMS AT KICT/KCNU EARLY THIS EVENING.
BILLINGS WRIGHT
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 66 92 69 95 / 20 0 10 10
HUTCHINSON 63 92 69 96 / 20 0 10 10
NEWTON 65 91 69 95 / 20 0 10 10
ELDORADO 65 91 68 94 / 30 10 10 10
WINFIELD-KWLD 67 92 69 95 / 30 10 10 10
RUSSELL 63 92 69 96 / 10 10 20 30
GREAT BEND 62 92 69 97 / 10 10 20 20
SALINA 64 93 69 97 / 20 0 20 20
MCPHERSON 64 92 69 96 / 20 0 10 20
COFFEYVILLE 69 91 69 94 / 40 20 20 10
CHANUTE 67 90 68 93 / 40 20 20 10
IOLA 67 89 68 93 / 40 20 10 10
PARSONS-KPPF 68 90 69 94 / 40 20 20 10
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
208 PM EDT THU AUG 28 2014
.UPDATE...
ISSUED AT 1229 PM EDT THU AUG 28 2014
THE STRATUS DECK HAS PROVEN TO BE AS FORMIDABLE AS ONE SEEN DURING
THE WINTER SEASON. THE LATEST VISIBLE SATELLITE TRENDS DO SHOW SOME
EROSION AND THINNING OVER THE PAST HOUR...BUT WILL HAVE TO HAVE
FURTHER REFINE THE SKY COVER INTO THE AFTERNOON AND CONSEQUENTLY
TEMPERATURE TRENDS. OUTSIDE THE THICKER CLOUD COVER...READINGS HAVE
SPIKED TO AS WARM AS THE 87 DEGREE MARK...CURRENTLY BEING REPORTED AT
KEKQ. UPDATES WILL BE FORTHCOMING.
UPDATE ISSUED AT 931 AM EDT THU AUG 28 2014
A CONTINUOUS STRATUS LAYER HAS ENSHROUDED NORTHEASTERN KENTUCKY
THROUGH THE MID-MORNING. VISIBILITIES HAVE IMPROVED IN THE
VALLEYS...WITH MOST LOCATIONS REPORTING A MILE OR ABOVE NOW. HAVE
BEEFED UP THE SKY COVER ACROSS THIS AREA AND ALSO ACCORDINGLY
TEMPERED THE DIURNAL TEMPERATURE RISE. THIS DECK WILL GRADUALLY BURN
OFF THROUGH AROUND 11 AM. HAVE ALSO RESERVED THE ISOLATED POPS UNTIL
THE AFTERNOON HOURS...ACCORDING TO THE LATEST HRRR MODEL GUIDANCE
TRENDS. THE HIGH TEMPERATURES LOOK ON TRACK. UPDATED PRODUCTS WILL
BE OUT SHORTLY.
UPDATE ISSUED AT 655 AM EDT THU AUG 28 2014
SO FAR FORECAST SEEMS TO BE WELL ON TRACK WITH ONGOING CONDITIONS.
RESIDUAL CLOUD COVER OVER THE FAR EASTERN PORTION OF THE CWA HAS
DEVELOPED AFTER SOME PASSING SHOWERS AND THUNDERSTORMS OCCURRED JUST
EAST OF OUR BORDER. OTHERWISE...FOG DEVELOPMENT /ESPECIALLY IN THE
VALLEYS/ HAS LED TO VV CIGS ACROSS PORTIONS OF EASTERN KY. FOG IS
SHOWING SIGNS OF LIFTING AT THE TAF SITES OVER THE LAST HOUR...AND AS
HAS BEEN THE CASE IN PREVIOUS MORNINGS...SHOULD CONTINUE TO LIFT AND
BURN OFF THROUGH 10AM. LOADED IN THE LATEST OBSERVATIONAL DATA TO THE
ONGOING NEAR TERM FORECAST TO MAKE SURE ONGOING TEMPERATURES...DEW
POINTS...AND WINDS WERE WELL REFLECTED.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 330 AM EDT THU AUG 28 2014
A WEAK SURFACE COLD FRONT CONTINUES TO PUSH SOUTHWARD ACROSS THE
REGION ATTM. HIGH PRESSURE IS RETREATING JUST TO THE SOUTH OF THE
REGION...AND A BROADER AREA OF HIGH PRESSURE IS MOVING IN BEHIND THE
FRONTAL BOUNDARY TO OUR NORTH. THIS BOUNDARY IS STILL EXPECTED TO
LOSE STRENGTH AND STALL OUT JUST S OF KY BY LATE IN THE DAY TODAY.
THE EXISTENCE OF THE BOUNDARY AND WARM/HUMID TEMPERATURES WILL BE
ENOUGH TO SPAWN SOME ISOLATED CHANCES OF SHOWERS AND THUNDERSTORMS
ACROSS THE SOUTHERN EXTENT OF THE CWA DURING THIS TIME...WHILE
INCOMING HIGH PRESSURE SHOULD KEEP CONDITIONS DRY ACROSS THE NORTHERN
CWA. LOSS OF DAYTIME HEATING WILL QUICKLY BRING AN END TO ANY
CONVECTION BY THIS EVENING.
OVERALL TONIGHT LOOKS TO BE QUIET WITH JUST A FEW CLOUDS LINGERING
AROUND. BY TOMORROW...THE STATIONARY FRONT WILL MAKE SHIFT BACK
NORTHWARDS AS A WARM FRONT...ATTACHED TO SURFACE LOW QUICKLY MOVING
FROM SW TO NE ACROSS THE GREAT PLAINS STATES. BEHIND THE WARM
FRONT...A SURGE OF WARMER...MOIST...GULF AIR WILL ADVECT INTO THE
REGION. TEMPERATURES WILL RISE INTO THE UPPER 80S TO AROUND 90
ACROSS MUCH OF EASTERN KY...WITH HUMIDITY LEVELS CAUSING HEAT
INDEXES TO PEAK A FEW DEGREES HIGHER. THE FRONT WILL STILL BE
WEAK...BUT THE INFLUX OF MOISTURE AND INSTABILITY WILL BE ENOUGH TO
SPAWN ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ACROSS MUCH OF
KY BY THE AFTERNOON AND CONTINUING INTO THE EVENING HOURS.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 420 AM EDT THU AUG 28 2014
THE MODEL CONSENSUS CONTINUES TO INDICATE THAT AN UPPER LEVEL RIDGE
OF HIGH PRESSURE WILL BE CENTERED TO OUR SOUTH OR SOUTHEAST THROUGH
MUCH OF THE PERIOD. A SHORTWAVE TROUGH WILL GRADUALLY PROGRESS FROM
THE ROCKIES INTO THE PLAINS IN THE NEAR TERM AND THEN TRACK GENERALLY
TO OUR NORTH INTO THE GREAT LAKES OVER THE WEEKEND. WEAKER
DISTURBANCES INITIALLY OVER TX OR THE WESTERN GULF OF MEXICO...OR AT
LEAST SOME OF THE DEEP MOISTURE ASSOCIATED WITH THEM ARE PROGGED TO
WORK AROUND THE BACKSIDE OF THE RIDGE AND INTO THE TN AND OH VALLEY
REGION FROM SAT INTO SUN NIGHT. THE PATTERN WILL GENERALLY THEN
EVOLVE TO A BROAD TROUGH STRETCHING FROM THE INTERMOUNTAIN WEST INTO
THE PLAINS BY THE END OF THE WEEKEND AND INTO EARLY NEXT WEEK.
HOWEVER...THE OVERALL TREND IS FOR THIS TROUGH TO FINALLY SWING EAST
TO OUR NORTH BY THE MIDDLE OF NEXT WEEK WITH OUR FLOW FLATTENING BACK
OUT. BEFORE THAT HAPPENS...A SOUTHWEST FLOW PATTERN WILL BE IN PLACE
OVER THE BLUEGRASS STATE.
AT THE SURFACE...A WARM FRONT WILL BE WORKING NORTH AND SHOULD EXIT
TO THE NORTH AND EAST EARLY IN THE PERIOD AS THE ABOVE MENTIONED
INITIAL SHORTWAVE WORKS TOWARD THE GREAT LAKES. AN ISOLATED SHOWER
OR STORM WILL REMAIN POSSIBLE EARLY IN THE PERIOD...ON FRIDAY NIGHT
AS THE REGION GETS INTO THE WARM SECTOR AND THE WARM FRONT DEPARTS.
ANOTHER COLD FRONT SHOULD SLOWLY MOVE FROM THE PLAINS OVER THE
WEEKEND...AND TOWARD THE AREA BY THE MIDDLE OF NEXT WEEK...GRADUALLY
STRETCHING OUT WEST TO EAST BY THE INCREASINGLY WEST TO EAST
ORIENTED RIDGE OVER THE SOUTHEASTERN CONUS. THE MODELS CONTINUE TO
INDICATE THAT SOUTHWEST FLOW IN ADVANCE OF THIS FRONT...IN ADDITION
TO THE PASSING OF DISTURBANCES ALOFT...WILL FUEL PERIODS OF SHOWERS
AND THUNDERSTORMS DURING THE HOLIDAY WEEKEND. THE EXACT TIMING OF
THESE DISTURBANCES REMAINS SOMEWHAT UNCERTAIN.
AT THIS TIME...IT STILL APPEARS THAT COVERAGE OF CONVECTION SHOULD
BE THE LEAST ON FRIDAY NIGHT INTO THE DAY ON SATURDAY. BY SAT EVENING
AND INTO SATURDAY NIGHT...RAIN CHANCES INCREASE AND PEAK SUNDAY AS
THE DISTURBANCES IN THE SOUTHWEST FLOW WORK OVERHEAD. MODELS
CONTINUE TO INDICATE THAT PWATS INCREASE TO AROUND TWO INCHES...IF
NOT ABOVE TWO INCHES SATURDAY NIGHT AND REMAIN AROUND TWO INCHES INTO
MONDAY. PWATS MAY LOWER SOME IN THE SOUTHERN PART OF THE AREA LATE
MONDAY INTO TUESDAY PER RECENT GUIDANCE...BUT THEY ARE EXPECTED TO
REMAIN NEARER TO TWO INCHES CLOSER TO THE OHIO RIVER IN ADVANCE OF
THE SLOWLY APPROACHING COLD FRONT. SO THE THREAT FOR HEAVY RAINFALL
REMAINS A CONCERN DURING MUCH OF THE EXTENDED PERIOD...ESPECIALLY
FROM SAT EVENING INTO LATE SUNDAY NIGHT AND POSSIBLY LATE IN THE
PERIOD ON TUE INTO TUE NIGHT AS THE NEXT FRONT SAGS INTO THE REGION.
DRIER AIR SHOULD BEGIN TO ADVECT INTO THE AREA TUESDAY NIGHT INTO
WEDNESDAY AS A COLD FRONT FINALLY SAGS INTO THE REGION. CONFIDENCE IN
THE TIMING OF THIS FEATURE REMAINS LOW...AND WE HAVE CONTINUED TO
MAINTAIN A MENTION OF SHOWERS/STORMS THROUGH THE END OF THE PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 208 PM EDT THU AUG 28 2014
MVFR STRATOCU WILL SCATTER OUT AND LIFT THROUGH 19Z. A FEW SHOWERS
AND A STRAY THUNDERSTORM WILL BE SEEN GENERALLY ALONG AND SOUTH OF
THE HAL ROGERS PARKWAY AND HIGHWAY 80 CORRIDORS THROUGH EARLY THIS
EVENING. GIVEN THE ISOLATED AREAL COVERAGE...DECIDED TO LEAVE OUT
ANY CONVECTIVE MENTION AT LOZ AND SME. ANY ACTIVITY WILL DIMINISH
QUICKLY BY AROUND 01Z...WITH FOG DEVELOPING ONCE AGAIN BETWEEN 05 AND
10Z. HAVE KEPT THINGS MVFR FOR THE TAF SITES...AS WINDS WILL BE
VEERING AROUND TO A LIGHT SOUTHEASTERLY COMPONENT. IFR OR WORSE FOG
IS EXPECTED ONCE AGAIN IN THE DEEPER RIVER VALLEYS. THE FOG WILL BE
BURNING OFF BY AROUND 13Z FRIDAY...WITH SOME ISOLATED CONVECTION
THREATENING ONCE AGAIN BY FRIDAY AFTERNOON.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...JMW
LONG TERM...ABE/JP
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
1229 PM EDT THU AUG 28 2014
.UPDATE...
ISSUED AT 1229 PM EDT THU AUG 28 2014
THE STRATUS DECK HAS PROVEN TO BE AS FORMIDABLE AS ONE SEEN DURING
THE WINTER SEASON. THE LATEST VISIBLE SATELLITE TRENDS DO SHOW SOME
EROSION AND THINNING OVER THE PAST HOUR...BUT WILL HAVE TO HAVE
FURTHER REFINE THE SKY COVER INTO THE AFTERNOON AND CONSEQUENTLY
TEMPERATURE TRENDS. OUTSIDE THE THICKER CLOUD COVER...READINGS HAVE
SPIKED TO AS WARM AS THE 87 DEGREE MARK...CURRENTLY BEING REPORTED AT
KEKQ. UPDATES WILL BE FORTHCOMING.
UPDATE ISSUED AT 931 AM EDT THU AUG 28 2014
A CONTINUOUS STRATUS LAYER HAS ENSHROUDED NORTHEASTERN KENTUCKY
THROUGH THE MID-MORNING. VISIBILITIES HAVE IMPROVED IN THE
VALLEYS...WITH MOST LOCATIONS REPORTING A MILE OR ABOVE NOW. HAVE
BEEFED UP THE SKY COVER ACROSS THIS AREA AND ALSO ACCORDINGLY
TEMPERED THE DIURNAL TEMPERATURE RISE. THIS DECK WILL GRADUALLY BURN
OFF THROUGH AROUND 11 AM. HAVE ALSO RESERVED THE ISOLATED POPS UNTIL
THE AFTERNOON HOURS...ACCORDING TO THE LATEST HRRR MODEL GUIDANCE
TRENDS. THE HIGH TEMPERATURES LOOK ON TRACK. UPDATED PRODUCTS WILL
BE OUT SHORTLY.
UPDATE ISSUED AT 655 AM EDT THU AUG 28 2014
SO FAR FORECAST SEEMS TO BE WELL ON TRACK WITH ONGOING CONDITIONS.
RESIDUAL CLOUD COVER OVER THE FAR EASTERN PORTION OF THE CWA HAS
DEVELOPED AFTER SOME PASSING SHOWERS AND THUNDERSTORMS OCCURRED JUST
EAST OF OUR BORDER. OTHERWISE...FOG DEVELOPMENT /ESPECIALLY IN THE
VALLEYS/ HAS LED TO VV CIGS ACROSS PORTIONS OF EASTERN KY. FOG IS
SHOWING SIGNS OF LIFTING AT THE TAF SITES OVER THE LAST HOUR...AND AS
HAS BEEN THE CASE IN PREVIOUS MORNINGS...SHOULD CONTINUE TO LIFT AND
BURN OFF THROUGH 10AM. LOADED IN THE LATEST OBSERVATIONAL DATA TO THE
ONGOING NEAR TERM FORECAST TO MAKE SURE ONGOING TEMPERATURES...DEW
POINTS...AND WINDS WERE WELL REFLECTED.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 330 AM EDT THU AUG 28 2014
A WEAK SURFACE COLD FRONT CONTINUES TO PUSH SOUTHWARD ACROSS THE
REGION ATTM. HIGH PRESSURE IS RETREATING JUST TO THE SOUTH OF THE
REGION...AND A BROADER AREA OF HIGH PRESSURE IS MOVING IN BEHIND THE
FRONTAL BOUNDARY TO OUR NORTH. THIS BOUNDARY IS STILL EXPECTED TO
LOSE STRENGTH AND STALL OUT JUST S OF KY BY LATE IN THE DAY TODAY.
THE EXISTENCE OF THE BOUNDARY AND WARM/HUMID TEMPERATURES WILL BE
ENOUGH TO SPAWN SOME ISOLATED CHANCES OF SHOWERS AND THUNDERSTORMS
ACROSS THE SOUTHERN EXTENT OF THE CWA DURING THIS TIME...WHILE
INCOMING HIGH PRESSURE SHOULD KEEP CONDITIONS DRY ACROSS THE NORTHERN
CWA. LOSS OF DAYTIME HEATING WILL QUICKLY BRING AN END TO ANY
CONVECTION BY THIS EVENING.
OVERALL TONIGHT LOOKS TO BE QUIET WITH JUST A FEW CLOUDS LINGERING
AROUND. BY TOMORROW...THE STATIONARY FRONT WILL MAKE SHIFT BACK
NORTHWARDS AS A WARM FRONT...ATTACHED TO SURFACE LOW QUICKLY MOVING
FROM SW TO NE ACROSS THE GREAT PLAINS STATES. BEHIND THE WARM
FRONT...A SURGE OF WARMER...MOIST...GULF AIR WILL ADVECT INTO THE
REGION. TEMPERATURES WILL RISE INTO THE UPPER 80S TO AROUND 90
ACROSS MUCH OF EASTERN KY...WITH HUMIDITY LEVELS CAUSING HEAT
INDEXES TO PEAK A FEW DEGREES HIGHER. THE FRONT WILL STILL BE
WEAK...BUT THE INFLUX OF MOISTURE AND INSTABILITY WILL BE ENOUGH TO
SPAWN ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ACROSS MUCH OF
KY BY THE AFTERNOON AND CONTINUING INTO THE EVENING HOURS.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 420 AM EDT THU AUG 28 2014
THE MODEL CONSENSUS CONTINUES TO INDICATE THAT AN UPPER LEVEL RIDGE
OF HIGH PRESSURE WILL BE CENTERED TO OUR SOUTH OR SOUTHEAST THROUGH
MUCH OF THE PERIOD. A SHORTWAVE TROUGH WILL GRADUALLY PROGRESS FROM
THE ROCKIES INTO THE PLAINS IN THE NEAR TERM AND THEN TRACK GENERALLY
TO OUR NORTH INTO THE GREAT LAKES OVER THE WEEKEND. WEAKER
DISTURBANCES INITIALLY OVER TX OR THE WESTERN GULF OF MEXICO...OR AT
LEAST SOME OF THE DEEP MOISTURE ASSOCIATED WITH THEM ARE PROGGED TO
WORK AROUND THE BACKSIDE OF THE RIDGE AND INTO THE TN AND OH VALLEY
REGION FROM SAT INTO SUN NIGHT. THE PATTERN WILL GENERALLY THEN
EVOLVE TO A BROAD TROUGH STRETCHING FROM THE INTERMOUNTAIN WEST INTO
THE PLAINS BY THE END OF THE WEEKEND AND INTO EARLY NEXT WEEK.
HOWEVER...THE OVERALL TREND IS FOR THIS TROUGH TO FINALLY SWING EAST
TO OUR NORTH BY THE MIDDLE OF NEXT WEEK WITH OUR FLOW FLATTENING BACK
OUT. BEFORE THAT HAPPENS...A SOUTHWEST FLOW PATTERN WILL BE IN PLACE
OVER THE BLUEGRASS STATE.
AT THE SURFACE...A WARM FRONT WILL BE WORKING NORTH AND SHOULD EXIT
TO THE NORTH AND EAST EARLY IN THE PERIOD AS THE ABOVE MENTIONED
INITIAL SHORTWAVE WORKS TOWARD THE GREAT LAKES. AN ISOLATED SHOWER
OR STORM WILL REMAIN POSSIBLE EARLY IN THE PERIOD...ON FRIDAY NIGHT
AS THE REGION GETS INTO THE WARM SECTOR AND THE WARM FRONT DEPARTS.
ANOTHER COLD FRONT SHOULD SLOWLY MOVE FROM THE PLAINS OVER THE
WEEKEND...AND TOWARD THE AREA BY THE MIDDLE OF NEXT WEEK...GRADUALLY
STRETCHING OUT WEST TO EAST BY THE INCREASINGLY WEST TO EAST
ORIENTED RIDGE OVER THE SOUTHEASTERN CONUS. THE MODELS CONTINUE TO
INDICATE THAT SOUTHWEST FLOW IN ADVANCE OF THIS FRONT...IN ADDITION
TO THE PASSING OF DISTURBANCES ALOFT...WILL FUEL PERIODS OF SHOWERS
AND THUNDERSTORMS DURING THE HOLIDAY WEEKEND. THE EXACT TIMING OF
THESE DISTURBANCES REMAINS SOMEWHAT UNCERTAIN.
AT THIS TIME...IT STILL APPEARS THAT COVERAGE OF CONVECTION SHOULD
BE THE LEAST ON FRIDAY NIGHT INTO THE DAY ON SATURDAY. BY SAT EVENING
AND INTO SATURDAY NIGHT...RAIN CHANCES INCREASE AND PEAK SUNDAY AS
THE DISTURBANCES IN THE SOUTHWEST FLOW WORK OVERHEAD. MODELS
CONTINUE TO INDICATE THAT PWATS INCREASE TO AROUND TWO INCHES...IF
NOT ABOVE TWO INCHES SATURDAY NIGHT AND REMAIN AROUND TWO INCHES INTO
MONDAY. PWATS MAY LOWER SOME IN THE SOUTHERN PART OF THE AREA LATE
MONDAY INTO TUESDAY PER RECENT GUIDANCE...BUT THEY ARE EXPECTED TO
REMAIN NEARER TO TWO INCHES CLOSER TO THE OHIO RIVER IN ADVANCE OF
THE SLOWLY APPROACHING COLD FRONT. SO THE THREAT FOR HEAVY RAINFALL
REMAINS A CONCERN DURING MUCH OF THE EXTENDED PERIOD...ESPECIALLY
FROM SAT EVENING INTO LATE SUNDAY NIGHT AND POSSIBLY LATE IN THE
PERIOD ON TUE INTO TUE NIGHT AS THE NEXT FRONT SAGS INTO THE REGION.
DRIER AIR SHOULD BEGIN TO ADVECT INTO THE AREA TUESDAY NIGHT INTO
WEDNESDAY AS A COLD FRONT FINALLY SAGS INTO THE REGION. CONFIDENCE IN
THE TIMING OF THIS FEATURE REMAINS LOW...AND WE HAVE CONTINUED TO
MAINTAIN A MENTION OF SHOWERS/STORMS THROUGH THE END OF THE PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 701 AM EDT THU AUG 28 2014
EXPECT FOG TO BURN OFF BETWEEN 12 AND 14Z AT TAF SITES ONCE MORE
THIS MORNING...WITH VFR CONDITIONS TAKING HOLD. A WEAK FRONTAL
BOUNDARY THAT PASSED THROUGH EASTERN KY LAST NIGHT...WILL BECOME
STATIONARY JUST SOUTH OF OUR AREA TODAY. THIS WILL BRING A THREAT OF
ISOLATED SHOWERS AND THUNDERSTORMS IN THE AFTERNOON NEAR THE TN AND
VA BORDERS. ALTHOUGH IT IS A SLIGHT CHANCE...WENT AHEAD AND KEPT
MENTION OF VCTS IN KLOZ AND KSME TAF FROM PREVIOUS FORECAST DURING
THE AFTERNOON. SKIES SHOULD QUICKLY CLEAR OVERNIGHT WITH LOSS OF
DAYTIME HEATING...WITH FOG EXPECTED TO MAKE A RETURN /ESPECIALLY IN
THE VALLEYS/ ONCE MORE. WINDS WILL REMAIN LIGHT AND VARIABLE THROUGH
THE PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...JMW
LONG TERM...ABE/JP
AVIATION...JMW
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
931 AM EDT THU AUG 28 2014
.UPDATE...
ISSUED AT 931 AM EDT THU AUG 28 2014
A CONTINUOUS STRATUS LAYER HAS ENSHROUDED NORTHEASTERN KENTUCKY
THROUGH THE MID-MORNING. VISIBILITIES HAVE IMPROVED IN THE
VALLEYS...WITH MOST LOCATIONS REPORTING A MILE OR ABOVE NOW. HAVE
BEEFED UP THE SKY COVER ACROSS THIS AREA AND ALSO ACCORDINGLY
TEMPERED THE DIURNAL TEMPERATURE RISE. THIS DECK WILL GRADUALLY BURN
OFF THROUGH AROUND 11 AM. HAVE ALSO RESERVED THE ISOLATED POPS UNTIL
THE AFTERNOON HOURS...ACCORDING TO THE LATEST HRRR MODEL GUIDANCE
TRENDS. THE HIGH TEMPERATURES LOOK ON TRACK. UPDATED PRODUCTS WILL
BE OUT SHORTLY.
UPDATE ISSUED AT 655 AM EDT THU AUG 28 2014
SO FAR FORECAST SEEMS TO BE WELL ON TRACK WITH ONGOING CONDITIONS.
RESIDUAL CLOUD COVER OVER THE FAR EASTERN PORTION OF THE CWA HAS
DEVELOPED AFTER SOME PASSING SHOWERS AND THUNDERSTORMS OCCURRED JUST
EAST OF OUR BORDER. OTHERWISE...FOG DEVELOPMENT /ESPECIALLY IN THE
VALLEYS/ HAS LED TO VV CIGS ACROSS PORTIONS OF EASTERN KY. FOG IS
SHOWING SIGNS OF LIFTING AT THE TAF SITES OVER THE LAST HOUR...AND AS
HAS BEEN THE CASE IN PREVIOUS MORNINGS...SHOULD CONTINUE TO LIFT AND
BURN OFF THROUGH 10AM. LOADED IN THE LATEST OBSERVATIONAL DATA TO THE
ONGOING NEAR TERM FORECAST TO MAKE SURE ONGOING TEMPERATURES...DEW
POINTS...AND WINDS WERE WELL REFLECTED.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 330 AM EDT THU AUG 28 2014
A WEAK SURFACE COLD FRONT CONTINUES TO PUSH SOUTHWARD ACROSS THE
REGION ATTM. HIGH PRESSURE IS RETREATING JUST TO THE SOUTH OF THE
REGION...AND A BROADER AREA OF HIGH PRESSURE IS MOVING IN BEHIND THE
FRONTAL BOUNDARY TO OUR NORTH. THIS BOUNDARY IS STILL EXPECTED TO
LOSE STRENGTH AND STALL OUT JUST S OF KY BY LATE IN THE DAY TODAY.
THE EXISTENCE OF THE BOUNDARY AND WARM/HUMID TEMPERATURES WILL BE
ENOUGH TO SPAWN SOME ISOLATED CHANCES OF SHOWERS AND THUNDERSTORMS
ACROSS THE SOUTHERN EXTENT OF THE CWA DURING THIS TIME...WHILE
INCOMING HIGH PRESSURE SHOULD KEEP CONDITIONS DRY ACROSS THE NORTHERN
CWA. LOSS OF DAYTIME HEATING WILL QUICKLY BRING AN END TO ANY
CONVECTION BY THIS EVENING.
OVERALL TONIGHT LOOKS TO BE QUIET WITH JUST A FEW CLOUDS LINGERING
AROUND. BY TOMORROW...THE STATIONARY FRONT WILL MAKE SHIFT BACK
NORTHWARDS AS A WARM FRONT...ATTACHED TO SURFACE LOW QUICKLY MOVING
FROM SW TO NE ACROSS THE GREAT PLAINS STATES. BEHIND THE WARM
FRONT...A SURGE OF WARMER...MOIST...GULF AIR WILL ADVECT INTO THE
REGION. TEMPERATURES WILL RISE INTO THE UPPER 80S TO AROUND 90
ACROSS MUCH OF EASTERN KY...WITH HUMIDITY LEVELS CAUSING HEAT
INDEXES TO PEAK A FEW DEGREES HIGHER. THE FRONT WILL STILL BE
WEAK...BUT THE INFLUX OF MOISTURE AND INSTABILITY WILL BE ENOUGH TO
SPAWN ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ACROSS MUCH OF
KY BY THE AFTERNOON AND CONTINUING INTO THE EVENING HOURS.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 420 AM EDT THU AUG 28 2014
THE MODEL CONSENSUS CONTINUES TO INDICATE THAT AN UPPER LEVEL RIDGE
OF HIGH PRESSURE WILL BE CENTERED TO OUR SOUTH OR SOUTHEAST THROUGH
MUCH OF THE PERIOD. A SHORTWAVE TROUGH WILL GRADUALLY PROGRESS FROM
THE ROCKIES INTO THE PLAINS IN THE NEAR TERM AND THEN TRACK GENERALLY
TO OUR NORTH INTO THE GREAT LAKES OVER THE WEEKEND. WEAKER
DISTURBANCES INITIALLY OVER TX OR THE WESTERN GULF OF MEXICO...OR AT
LEAST SOME OF THE DEEP MOISTURE ASSOCIATED WITH THEM ARE PROGGED TO
WORK AROUND THE BACKSIDE OF THE RIDGE AND INTO THE TN AND OH VALLEY
REGION FROM SAT INTO SUN NIGHT. THE PATTERN WILL GENERALLY THEN
EVOLVE TO A BROAD TROUGH STRETCHING FROM THE INTERMOUNTAIN WEST INTO
THE PLAINS BY THE END OF THE WEEKEND AND INTO EARLY NEXT WEEK.
HOWEVER...THE OVERALL TREND IS FOR THIS TROUGH TO FINALLY SWING EAST
TO OUR NORTH BY THE MIDDLE OF NEXT WEEK WITH OUR FLOW FLATTENING BACK
OUT. BEFORE THAT HAPPENS...A SOUTHWEST FLOW PATTERN WILL BE IN PLACE
OVER THE BLUEGRASS STATE.
AT THE SURFACE...A WARM FRONT WILL BE WORKING NORTH AND SHOULD EXIT
TO THE NORTH AND EAST EARLY IN THE PERIOD AS THE ABOVE MENTIONED
INITIAL SHORTWAVE WORKS TOWARD THE GREAT LAKES. AN ISOLATED SHOWER
OR STORM WILL REMAIN POSSIBLE EARLY IN THE PERIOD...ON FRIDAY NIGHT
AS THE REGION GETS INTO THE WARM SECTOR AND THE WARM FRONT DEPARTS.
ANOTHER COLD FRONT SHOULD SLOWLY MOVE FROM THE PLAINS OVER THE
WEEKEND...AND TOWARD THE AREA BY THE MIDDLE OF NEXT WEEK...GRADUALLY
STRETCHING OUT WEST TO EAST BY THE INCREASINGLY WEST TO EAST
ORIENTED RIDGE OVER THE SOUTHEASTERN CONUS. THE MODELS CONTINUE TO
INDICATE THAT SOUTHWEST FLOW IN ADVANCE OF THIS FRONT...IN ADDITION
TO THE PASSING OF DISTURBANCES ALOFT...WILL FUEL PERIODS OF SHOWERS
AND THUNDERSTORMS DURING THE HOLIDAY WEEKEND. THE EXACT TIMING OF
THESE DISTURBANCES REMAINS SOMEWHAT UNCERTAIN.
AT THIS TIME...IT STILL APPEARS THAT COVERAGE OF CONVECTION SHOULD
BE THE LEAST ON FRIDAY NIGHT INTO THE DAY ON SATURDAY. BY SAT EVENING
AND INTO SATURDAY NIGHT...RAIN CHANCES INCREASE AND PEAK SUNDAY AS
THE DISTURBANCES IN THE SOUTHWEST FLOW WORK OVERHEAD. MODELS
CONTINUE TO INDICATE THAT PWATS INCREASE TO AROUND TWO INCHES...IF
NOT ABOVE TWO INCHES SATURDAY NIGHT AND REMAIN AROUND TWO INCHES INTO
MONDAY. PWATS MAY LOWER SOME IN THE SOUTHERN PART OF THE AREA LATE
MONDAY INTO TUESDAY PER RECENT GUIDANCE...BUT THEY ARE EXPECTED TO
REMAIN NEARER TO TWO INCHES CLOSER TO THE OHIO RIVER IN ADVANCE OF
THE SLOWLY APPROACHING COLD FRONT. SO THE THREAT FOR HEAVY RAINFALL
REMAINS A CONCERN DURING MUCH OF THE EXTENDED PERIOD...ESPECIALLY
FROM SAT EVENING INTO LATE SUNDAY NIGHT AND POSSIBLY LATE IN THE
PERIOD ON TUE INTO TUE NIGHT AS THE NEXT FRONT SAGS INTO THE REGION.
DRIER AIR SHOULD BEGIN TO ADVECT INTO THE AREA TUESDAY NIGHT INTO
WEDNESDAY AS A COLD FRONT FINALLY SAGS INTO THE REGION. CONFIDENCE IN
THE TIMING OF THIS FEATURE REMAINS LOW...AND WE HAVE CONTINUED TO
MAINTAIN A MENTION OF SHOWERS/STORMS THROUGH THE END OF THE PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 701 AM EDT THU AUG 28 2014
EXPECT FOG TO BURN OFF BETWEEN 12 AND 14Z AT TAF SITES ONCE MORE
THIS MORNING...WITH VFR CONDITIONS TAKING HOLD. A WEAK FRONTAL
BOUNDARY THAT PASSED THROUGH EASTERN KY LAST NIGHT...WILL BECOME
STATIONARY JUST SOUTH OF OUR AREA TODAY. THIS WILL BRING A THREAT OF
ISOLATED SHOWERS AND THUNDERSTORMS IN THE AFTERNOON NEAR THE TN AND
VA BORDERS. ALTHOUGH IT IS A SLIGHT CHANCE...WENT AHEAD AND KEPT
MENTION OF VCTS IN KLOZ AND KSME TAF FROM PREVIOUS FORECAST DURING
THE AFTERNOON. SKIES SHOULD QUICKLY CLEAR OVERNIGHT WITH LOSS OF
DAYTIME HEATING...WITH FOG EXPECTED TO MAKE A RETURN /ESPECIALLY IN
THE VALLEYS/ ONCE MORE. WINDS WILL REMAIN LIGHT AND VARIABLE THROUGH
THE PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...JMW
LONG TERM...ABE/JP
AVIATION...JMW
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
926 PM CDT FRI AUG 29 2014
.DISCUSSION...
MAIN SHRA/ISO TSRA AREA OVER THE GULF THIS EVENING...WITH
LIGHT/MOD SHRA SPREADING INLAND ACROSS SE TX/S LA. NOTABLE MID
LEVEL SPIN JUST OFF THE SE TX COAST...ASSOCIATED WITH THE REMNANT
MID LEVEL VORT MAX FROM THE EARLIER TSRA CLUSTER OVER THE NW GULF.
THE NAM & HRRR CONTINUES TO SIGNAL ADDITIONAL DEVELOPMENT OF
SHRA/TSRA OVER EXTREME SE TX/S LA BETWEEN 06-12Z...WITH POSSIBLE
TRAINING OF ECHOS SETTING UP TOWARDS DAYBREAK INTO THE REMAINDER
OF THE MORNING ONCE THIS REMNANT VORT MAX MOVES INLAND AND
INCREASED LIFT SETS UP FROM THE APPROACHING UPPER LEVEL TROF. WITH
THE HIGH PRECIP H20 VALUES ALREADY IN PLACE (00Z LCH SOUNDING @
2.27") WILL NOT TAKE MUCH TO GET 2-3" OF RAINFALL...WITH LOCALLY
HIGHER AMOUNTS OF 3-5" POSSIBLE BEFORE ALL SAID AND DONE BY SAT
EVENING/EARLY SUN. THIS WARRANTED THE ISSUANCE OF A FLASH FLOOD
WATCH FOR SE TX/C AND S LA. BELIEVE THE MAIN THREAT AREA FOR THE
OVERNIGHT HOURS WILL BE ALONG AND SOUTH OF I-10...WITH THIS AREA
SHIFTING NORTHWARD AFTER DAYBREAK FOR THE REMAINDER OF THE WATCH AREA.
DML
&&
.PREV DISCUSSION... /ISSUED 633 PM CDT FRI AUG 29 2014/
UPDATE...WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS NOW PRIMARILY
OVER THE NEAR COASTAL WATERS ARE EXPECTED TO MOVE INLAND AS THE
NIGHT PROGRESSES. THIS ACTIVITY IS ASSOCIATED WITH LOW
PRESSURE OVER THE NORTHWEST GULF ADVANCING NORTHWARD. INITIAL VFR
CEILINGS ARE EXPECTED TO SLIP DOWN WITHIN MVFR.
MARCOTTE
PREV DISCUSSION... /ISSUED 411 PM CDT FRI AUG 29 2014/
DISCUSSION...
SHOWERS HAVE DROPPED RAINS ACROSS A LARGE PORTION OF SE TX AND
SRN LA TODAY...GENERALLY LESS THAN 1/2 INCH MOST LOCATIONS. THIS
HAS HELP TO KEEP TEMPERATURES IN THE 80S. RAINS ARE FROM A LOW
OFF OF BRO THAT HAS BEEN DRAGGING MOISTURE NORTHWARD. THIS
PATTERN WILL CONTINUE INTO THE OVERNIGHT HOURS WITH ADDITIONAL
SHOWERS AND THUNDERSTORMS ON TAP. TEMPS WILL FALL INTO THE MID 70S
MOST LOCATIONS BUT A FEW LOCATIONS MAY SEE LOWER 70S WITH RAIN
COOLED AIR.
TOMORROW WILL SEE ANOTHER SURGE OF MOISTURE INTO THE REGION FROM
THE GULF AND RAIN CHANCES WILL INCREASE AND TEMPS ARE EXPECTED
BACK INTO THE 80S ONCE AGAIN. RAINFALL TOTALS EXPECTED AROUND ONE
TO TWO INCHES WITH ISOLATED LOCATIONS GETTING THREE TO FOUR
INCHES. THE MOISTURE AXIS WILL CONTINUE INTO SUNDAY BUT RAIN
CHANCES WILL TAPER OFF A BIT... BUT BY MONDAY HIGH PRESSURE WILL
BUILD IN FROM THE EAST AND THIS WILL BEGIN TO SHUT OFF OUR PRECIP.
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 74 85 75 89 76 / 90 90 50 40 10
KBPT 74 87 76 90 76 / 80 80 50 40 10
KAEX 73 84 72 89 73 / 70 90 50 40 10
KLFT 75 84 75 90 76 / 90 90 50 40 10
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...FLASH FLOOD WATCH THROUGH SATURDAY EVENING FOR THE FOLLOWING
ZONES: ACADIA...ALLEN...AVOYELLES...BEAUREGARD...
CALCASIEU...EAST CAMERON...EVANGELINE...IBERIA...JEFFERSON
DAVIS...LAFAYETTE...LOWER ST. MARTIN...RAPIDES...ST.
LANDRY...ST. MARY...UPPER ST. MARTIN...VERMILION...VERNON...
WEST CAMERON.
TX...FLASH FLOOD WATCH THROUGH SATURDAY EVENING FOR THE FOLLOWING
ZONES: JEFFERSON...ORANGE.
GM...SMALL CRAFT EXERCISE CAUTION UNTIL 7 AM CDT SATURDAY FOR THE
FOLLOWING ZONES: COASTAL WATERS FROM CAMERON LA TO HIGH
ISLAND TX OUT 20 NM...COASTAL WATERS FROM INTRACOASTAL CITY
TO CAMERON LA OUT 20 NM...COASTAL WATERS FROM LOWER
ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA OUT 20 NM...
WATERS FROM INTRACOASTAL CITY TO CAMERON LA FROM 20 TO 60
NM...WATERS FROM CAMERON LA TO HIGH ISLAND TX FROM 20 TO 60
NM...WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL
CITY LA FROM 20 TO 60 NM.
&&
$$
AREA FORECAST DISCUSSION
NWS NEW ORLEANS LA
823 AM CDT THU AUG 28 2014
.SOUNDING DISCUSSION...
CONDITIONS HAVEN/T CHANGED SIGNIFICANTLY FROM LAST EVENING/S
FLIGHT. STILL A VERY MOIST AIR MASS WITH PRECIPITABLE WATER OF
2.14 INCHES...OR ABOUT 120 PERCENT OF NORMAL FOR THIS TIME OF
YEAR. WITH THIS MUCH MOISTURE IN PLACE...ANY STORMS THAT DEVELOP
WILL BE CAPABLE OF PRODUCING VERY HIGH RAINFALL RATES. ALSO
AIDING IN RAINFALL PRODUCTION...LIGHT WINDS THROUGH MOST OF THE
COLUMN SHOULD RESULT IN A SLOW STORM MOTION. EXCEPTION WILL BE
ACROSS SOUTHWEST PORTIONS OF THE AREA WHERE THERE WILL BE MORE
INFLUENCE FROM THE UPPER LOW OVER THE NORTHWEST GULF. STORM MOTION
WILL BE CLOSER TO 15 KTS IN THIS AREA. ALSO STILL LOOKING AT AN
UNSTABLE AIR MASS WITH A LIFTED INDEX OF -4.4 AND CAPE OF AROUND
2600 J/KG. WITH DIURNAL HEATING BEING THE MAIN LIFTING MECHANISM
EXPECT MAINLY SHOWERS AND THUNDERSTORMS MAINLY IN THE AFTERNOON.
12Z BALLOON INFO: ROUTINE FLIGHT THIS MORNING WITH NO PROBLEMS.
THE BALLOON POPPED AT 7.1 MB...OR ABOUT 20.8 MILES ABOVE THE
GROUND. AT THE TIME IT POPPED...IT WAS LOCATED OVER NORTHERN LAKE
PONTCHARTRAIN.
&&
.PREV DISCUSSION... /ISSUED 346 AM CDT THU AUG 28 2014/
SHORT TERM...
NOT MUCH ON RADAR TO START OFF THE MORNING OTHER THAN A FEW SHOWERS
OFFSHORE. RAIN CHANCES WILL BE SIMILAR TO YESTERDAY FOR MOST
PORTIONS OF THE CWA EXPECT FOR LA COASTAL PARISHES WHERE POPS SHOULD
ONLY BE AROUND 30 PCT RATHER THAN 50S. THIS IS THE RESULT OF SURFACE
LOW IN THE WESTERN GULF CONTINUING TO TRACK FURTHER AWAY FROM THE
ARE. THE FCST IS IN THE MIDDLE BETWEEN THE GENERAL HRRR AND MODEST
GFS/ECMWF. EXPECTING HIGHER POPS TO BE IN THE WESTERN HALF OF THE
FORECAST AREA. MS COUNTIES MAY NOT SEE ANY CONVECTION.
LONG TERM...
AN UPPER LEVEL TROUGH MOVING EAST ACROSS THE CENTER OF THE ROCKY
MOUNTAINS THIS MORNING IS SPLITTING AN UPPER RIDGE THATS STRUGGLING
TO MAINTAIN ITSELF OVER THE SOUTHERN HALF OF THE COUNTRY AT THIS
TIME. BY DOING SO...THE GULF OF MEXICO WILL BE OPENED UP TO THE AREA
THROUGH THE WEEKEND WHICH WILL SET THE STAGE FOR EVEN HIGHER RAIN
CHANCES FRIDAY THROUGH SUNDAY. IMPULSES RIDING AROUND THE HIGH
CENTERED TO THE EAST WILL PASS OVER THE CWA THROUGH THIS PERIOD
WHICH WILL ENHANCE SHOWER AND THUNDERSTORM DEVELOPMENT. MODEL
SOUNDINGS SHOW ABUNDANT MOISTURE WILL BE IN PLACE WITH PRECIPITABLE
WATER VALUES ON THE ORDER OF 2 TO 2.25 INCHES. THUS THINKING
COVERAGE WILL BE FAIRLY WIDESPREAD AND RAINFALL RATES QUITE HEAVY.
HAVE INCREASED POPS ON SATURDAY TO 70 PERCENT AND THAT MAY NOT BE
HIGH ENOUGH. LOCALIZED FLOODING WILL LIKELY BE AN ISSUE IN SOME
AREAS. INCREASED CLOUD COVER AND WIDESPREAD CONVECTION SHOULD LIMIT
DAILY WARMING...SO HAVE KEPT HIGHS SLIGHTLY BELOW NORMAL.
RAIN CHANCES SHOULD START TO COME BACK DOWN STARTING NEXT WEEK AS
THE TROUGH TO THE NORTH FINALLY LIFTS AND UPPER RIDGE BUILDS BACK IN
ACROSS THE SOUTH. GFS AND ECMWF ARE SHOWING A TROPICAL WAVE MOVING
ACROSS THE YUCATAN PENINSULA GOING INTO THE MIDDLE OF NEXT WEEK. IT
REMAINS TO BE SEEN IF THIS SOLUTION MATERIALIZES. STILL WAY TOO FAR
OUT TO HAVE ANY CONCERN AT THIS POINT.
AVIATION...
VFR CONDITIONS WILL PREVAIL AT ALL OF THE TERMINALS THROUGH THE
FORECAST PERIOD WITH A SCATTERED TO BROKEN CU FIELD RUNNING AROUND
4-5K FEET. THERE MAY BE SOME LIGHT FOG DEVELOPMENT AROUND 10-12Z
THIS MORNING AT KASD...KHDC...AND KMCB WHICH COULD REDUCE
VISIBILITIES TO AROUND 4-5 MILES. ANY FOG SHOULD QUICKLY CLEAR AFTER
13Z...AS DAYTIME HEATING MIXES OUT THE BOUNDARY LAYER. SOME
SCATTERED CONVECTION MAY ALSO IMPACT KHUM BETWEEN 17Z AND 23Z. HAVE
INCLUDED VCTS WORDING TO REFLECT THIS RISK.
MARINE...
EAST-SOUTHEAST FLOW OF 10 TO 15 KNOTS AND SEAS OF 2 TO 4 FEET CAN BE
EXPECTED TODAY AS AN INVERTED TROUGH EXTENDING ACROSS THE WESTERN
GULF OF MEXICO SLOWLY MOVES INTO TEXAS. THIS INITIAL TROUGH WILL
MOVE INTO TEXAS TONIGHT...BUT ANOTHER INVERTED TROUGH AXIS WILL MOVE
NORTH INTO THE COASTAL WATERS TOMORROW. THIS TROUGH WILL KEEP
SOUTHEAST FLOW OF 10 TO 15 KNOTS IN PLACE THROUGH SATURDAY. SEAS
WILL INCREASE INTO THE 3 TO 5 FEET RANGE IN THE OFFSHORE WATERS AS A
1 TO 2 FOOT SWELL TRAIN DEVELOPS IN THE GULF. RIDGING WILL BUILD
WESTWARD FROM THE EASTERN GULF FOR THE LATTER HALF OF THE
WEEKEND...KEEPING SOUTHEAST FLOW OF 10 TO 15 KNOTS IN PLACE. THESE
CONDITIONS WILL PERSIST INTO TUESDAY.
DECISION SUPPORT...
DSS CODE...GREEN.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT..
DECISION SUPPORT SERVICES (DSS) CODE LEGEND
GREEN = NO WEATHER IMPACTS THAT REQUIRE ACTION
BLUE = LONG FUSED WATCH/WARNING/ADVISORY IN EFFECT OR HIGH
VISIBILITY EVENT
YELLOW = HEIGHTENED IMPACTS WITH SHORT FUSED
WATCH/WARNING/ADVISORY ISSUANCES; RADAR SUPPORT
ORANGE = HIGH IMPACTS - SLIGHT TO MODERATE RISK SEVERE; NEARBY
TROPICAL EVENTS; HAZMAT OR OTHER LARGE EPISODES
RED = FULL ENGAGEMENT FOR MODERATE TO HIGH RISK SVR
AND/OR DIRECT TROPICAL THREATS; EVENTS OF NATIONAL
SIGNIFICANCE.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 91 71 92 74 / 20 10 30 30
BTR 93 74 92 76 / 30 20 40 40
ASD 92 74 91 78 / 30 20 50 40
MSY 90 78 90 78 / 30 20 50 40
GPT 91 75 90 79 / 20 10 50 40
PQL 91 73 90 78 / 20 10 40 30
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&
$$
SOUNDING...95/DM
AVIATION/MARINE...32
SHORT/LONG...MEFFER
AREA FORECAST DISCUSSION
NWS NEW ORLEANS LA
346 AM CDT THU AUG 28 2014
.SHORT TERM...
NOT MUCH ON RADAR TO START OFF THE MORNING OTHER THAN A FEW SHOWERS
OFFSHORE. RAIN CHANCES WILL BE SIMILAR TO YESTERDAY FOR MOST
PORTIONS OF THE CWA EXPECT FOR LA COASTAL PARISHES WHERE POPS SHOULD
ONLY BE AROUND 30 PCT RATHER THAN 50S. THIS IS THE RESULT OF SURFACE
LOW IN THE WESTERN GULF CONTINUING TO TRACK FURTHER AWAY FROM THE
ARE. THE FCST IS IN THE MIDDLE BETWEEN THE GENERAL HRRR AND MODEST
GFS/ECMWF. EXPECTING HIGHER POPS TO BE IN THE WESTERN HALF OF THE
FORECAST AREA. MS COUNTIES MAY NOT SEE ANY CONVECTION.
.LONG TERM...
AN UPPER LEVEL TROUGH MOVING EAST ACROSS THE CENTER OF THE ROCKY
MOUNTAINS THIS MORNING IS SPLITTING AN UPPER RIDGE THATS STRUGGLING
TO MAINTAIN ITSELF OVER THE SOUTHERN HALF OF THE COUNTRY AT THIS
TIME. BY DOING SO...THE GULF OF MEXICO WILL BE OPENED UP TO THE AREA
THROUGH THE WEEKEND WHICH WILL SET THE STAGE FOR EVEN HIGHER RAIN
CHANCES FRIDAY THROUGH SUNDAY. IMPULSES RIDING AROUND THE HIGH
CENTERED TO THE EAST WILL PASS OVER THE CWA THROUGH THIS PERIOD
WHICH WILL ENHANCE SHOWER AND THUNDERSTORM DEVELOPMENT. MODEL
SOUNDINGS SHOW ABUNDANT MOISTURE WILL BE IN PLACE WITH PRECIPITABLE
WATER VALUES ON THE ORDER OF 2 TO 2.25 INCHES. THUS THINKING
COVERAGE WILL BE FAIRLY WIDESPREAD AND RAINFALL RATES QUITE HEAVY.
HAVE INCREASED POPS ON SATURDAY TO 70 PERCENT AND THAT MAY NOT BE
HIGH ENOUGH. LOCALIZED FLOODING WILL LIKELY BE AN ISSUE IN SOME
AREAS. INCREASED CLOUD COVER AND WIDESPREAD CONVECTION SHOULD LIMIT
DAILY WARMING...SO HAVE KEPT HIGHS SLIGHTLY BELOW NORMAL.
RAIN CHANCES SHOULD START TO COME BACK DOWN STARTING NEXT WEEK AS
THE TROUGH TO THE NORTH FINALLY LIFTS AND UPPER RIDGE BUILDS BACK IN
ACROSS THE SOUTH. GFS AND ECMWF ARE SHOWING A TROPICAL WAVE MOVING
ACROSS THE YUCATAN PENINSULA GOING INTO THE MIDDLE OF NEXT WEEK. IT
REMAINS TO BE SEEN IF THIS SOLUTION MATERIALIZES. STILL WAY TOO FAR
OUT TO HAVE ANY CONCERN AT THIS POINT.
MEFFER
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL AT ALL OF THE TERMINALS THROUGH THE
FORECAST PERIOD WITH A SCATTERED TO BROKEN CU FIELD RUNNING AROUND
4-5K FEET. THERE MAY BE SOME LIGHT FOG DEVELOPMENT AROUND 10-12Z
THIS MORNING AT KASD...KHDC...AND KMCB WHICH COULD REDUCE
VISIBILITIES TO AROUND 4-5 MILES. ANY FOG SHOULD QUICKLY CLEAR AFTER
13Z...AS DAYTIME HEATING MIXES OUT THE BOUNDARY LAYER. SOME
SCATTERED CONVECTION MAY ALSO IMPACT KHUM BETWEEN 17Z AND 23Z. HAVE
INCLUDED VCTS WORDING TO REFLECT THIS RISK. 32
&&
.MARINE...
EAST-SOUTHEAST FLOW OF 10 TO 15 KNOTS AND SEAS OF 2 TO 4 FEET CAN BE
EXPECTED TODAY AS AN INVERTED TROUGH EXTENDING ACROSS THE WESTERN
GULF OF MEXICO SLOWLY MOVES INTO TEXAS. THIS INITIAL TROUGH WILL
MOVE INTO TEXAS TONIGHT...BUT ANOTHER INVERTED TROUGH AXIS WILL MOVE
NORTH INTO THE COASTAL WATERS TOMORROW. THIS TROUGH WILL KEEP
SOUTHEAST FLOW OF 10 TO 15 KNOTS IN PLACE THROUGH SATURDAY. SEAS
WILL INCREASE INTO THE 3 TO 5 FEET RANGE IN THE OFFSHORE WATERS AS A
1 TO 2 FOOT SWELL TRAIN DEVELOPS IN THE GULF. RIDGING WILL BUILD
WESTWARD FROM THE EASTERN GULF FOR THE LATTER HALF OF THE
WEEKEND...KEEPING SOUTHEAST FLOW OF 10 TO 15 KNOTS IN PLACE. THESE
CONDITIONS WILL PERSIST INTO TUESDAY. 32
&&
.DECISION SUPPORT...
DSS CODE...GREEN.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT..
DECISION SUPPORT SERVICES (DSS) CODE LEGEND
GREEN = NO WEATHER IMPACTS THAT REQUIRE ACTION
BLUE = LONG FUSED WATCH/WARNING/ADVISORY IN EFFECT OR HIGH
VISIBILITY EVENT
YELLOW = HEIGHTENED IMPACTS WITH SHORT FUSED
WATCH/WARNING/ADVISORY ISSUANCES; RADAR SUPPORT
ORANGE = HIGH IMPACTS - SLIGHT TO MODERATE RISK SEVERE; NEARBY
TROPICAL EVENTS; HAZMAT OR OTHER LARGE EPISODES
RED = FULL ENGAGEMENT FOR MODERATE TO HIGH RISK SVR
AND/OR DIRECT TROPICAL THREATS; EVENTS OF NATIONAL
SIGNIFICANCE.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 91 71 92 74 / 20 10 30 30
BTR 93 74 92 76 / 30 20 40 40
ASD 92 74 91 78 / 30 20 50 40
MSY 90 78 90 78 / 30 20 50 40
GPT 91 75 90 79 / 20 10 50 40
PQL 91 73 90 78 / 20 10 40 30
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
641 PM CDT Fri Aug 29 2014
.DISCUSSION...
Issued at 401 PM CDT FRI AUG 29 2014
Out of the gate this afternoon...first round of convection continuing
to track east-northeast as initial shot of vorticity and pressure
advection associated with inbound upper wave slides east across the
region. Upstream behind this afternoon/s activity...skies have
cleared and weak destabilization has occurred with latest SPC
mesoanalysis suggesting anywhere between 1000-1500 J/Kg of MLCAPE
exists across eastern KS and western MO. Heading into the late
afternoon...main concern is for redeveloping convection as next piece
of shortwave energy and associated vorticity slides over the area. As
this occurs...long-lived frontal boundary which has been in place
across the central Plains in recent days should slowly slide across
the region which should also help with possible redevelopment. Fcst
models have been playing this card quite well with latest HRRR high-
res data supporting renewed convection across eastern KS this afternoon.
For now...have advertised chc pops pretty much across the western
2/3rds of the fcst area...before gradually spreading them east during
the early overnight period. In terms of severe threats...latest
mesoanalysis shows fairly weak shear aloft. This along with a DCAPE
min/trough across our region should largely prevent widespread
severe. That said though...a few strong downbursts cannot be ruled
out if convection actually does develop.
Main front to slide through the forecast area tonight as discussed
above. This should result in a gradual decrease in storm coverage
from west to east during the early morning hrs if storms do in fact
develop. Overnight lows tonight will largely reside in the middle to
upper 60s.
By all accounts...upcoming holiday weekend shaping up to be
beautiful...at least early on that is as region will reside in a post
frontal airmass both Saturday and Sunday. Despite the fropa
tonight...limited to no cooling seeing in the 850-mb temp field thus
expect high temps in the mid to upper 80s on Saturday...and
potentially into the lower to middle 90s on Sunday as warm air
advection increases ahead of next incoming wave/front.
Much more interesting weather by Sunday night/early Monday as well
advertised longwave trough continues to dig along the Front Range. As
this occurs...cyclogenesis expected across the northern Plains with
strengthening future then expected to quickly exit into the upper
Miss Vly/western Great Lakes region by early Monday. The end result
for our area will be a slowly progressing cold front which will begin
sliding south during this period...with increasing chances for rain
from Sunday night through the Tuesday time frame. Main issue seen
from this vantage point is that this feature will likely stall
somewhere across central Missouri as it begins to interact with stout
sfc ridging in place across the lwr Miss Vly and southern Plains. A
severe wx concern initially Sunday night may quickly morph into a
hydro concern as continued moisture advection resulting from a
strengthening low-level jet of 2-3 standard deviations above normal
ascends the stalled feature and cloud layer winds remain parallel to
the front. Will have to maintain vigilance with this feature as many
locations across our northwestern zones have received heavy rainfall
in recent days. If severe wx were to develop Sunday night...bulk
shear vectors orientation parallel to the incoming front will likely
support multicell type storm morphologies...with high winds winds
posing the biggest threat before concerns change over to possible
heavy rain. That said...better frontal convergence for forced ascent
will likely remain north of our fcst area which could ultimately
limit the severe threat for our region. In any event...both flooding
and possible severe pose a risk as seen this afternoon and will
maintain mention in the HWO product for now.
Beyond this...returning southerly flow will finally lift the front
north across the region with dry weather returning in its wake by
midweek. With zonal flow expected to dominate across the lower
48...temps through the conclusion of the period should remain near or
slightly above normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday Evening)
Issued at 640 PM CDT FRI AUG 29 2014
Scattered thunderstorms continue to bubble up in the heat of the late
afternoon and will likely affect the terminals through the mid to
late evening hours of tonight. Ceilings in the vicinity of the storms
are not particularly low but and torrential rain with these storms
might greatly reduce visibilities for brief periods. Expect the focus
for these storms to either dissipate or shift east of the terminals
late tonight which could clear skies out enough for some early
morning haze or fog. Lastly, expect winds to veer around to the
west by Saturday morning.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
DISCUSSION...32
AVIATION...Cutter
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
921 PM MDT FRI AUG 29 2014
.UPDATE...
COLD FRONT THAT WILL MOVE THROUGH THE AREA EARLY SATURDAY HAS
MOVED THROUGH BURNS OREGON SO THAT LOOKS ON TRACK FOR A 12-14Z
ARRIVAL IN BILLINGS. RAP MODEL PREVENTS THE CONVECTION CURRENTLY
OVER SOUTHWEST MONTANA FROM ADVANCING TOO FAR INTO THE PLAINS
OVERNIGHT. CURRENT FORECAST COVERS THESE DETAILS WELL. NO UPDATES.
BORSUM
&&
.SHORT TERM...VALID FOR SAT AND SUN...
SHORTWAVE RIDGING IS BUILDING IN OVER THE FORECAST AREA LATE THIS
AFTERNOON...RESULTING IN MAINLY CLEAR SKIES WITH SOME FAIR WEATHER
CUMULUS CLOUDS ACROSS EASTERN MONTANA IN THE WAKE OF THIS MORNINGS
SHORTWAVE PASSAGE. A FAIR EVENING AND NIGHT IS IN STORE FOR SOUTH
CENTRAL AND SOUTHEAST MONTANA...WITH NEAR NORMAL OVERNIGHT LOW
TEMPERATURES.
ANOTHER SHORTWAVE IS APPROACHING THE FORECAST AREA FROM THE
WEST...AND CAN CURRENTLY BE SEEN IN WV IMAGERY COMING ON SHORE IN
THE PACIFIC NORTHWEST. THIS WAVE WILL TRAVERSE THE FORECAST AREA
DURING THE DAY SATURDAY. SHOWER AND THUNDERSTORM ACTIVITY WILL
APPROACH LIVINGSTON BY AROUND 12Z AND WILL SPREAD EASTWARD
BECOMING MORE WIDESPREAD AND CONVECTIVE BY THE AFTERNOON. THE
STRONGEST INSTABILITY WILL BE ACROSS FAR EASTERN MONTANA...NEAR
FALLON AND CARTER COUNTIES...ALONG WITH INCREASING SHEAR INTO THE
AFTERNOON. THUS THE THREAT FOR ISOLATED SEVERE THUNDERSTORMS IS
POSSIBLE IN THE EARLY AFTERNOON THERE...HOWEVER...EXPECT THE
THREAT WILL QUICKLY EVOLVE EASTWARD INTO THE DAKOTAS GIVEN THE
TIME OF THE WAVE. FORECAST MODELS CONTINUE TO INDICATE SOME WEAK
INSTABILITY LINGERING ACROSS CENTRAL AND WESTERN ZONES BEHIND THE
FRONT ON SATURDAY AFTERNOON. EXPECT TO SEE NUMEROUS SHOWERS AND
THUNDERSTORMS FROM BILLINGS WEST BY THE AFTERNOON...WITH EMBEDDED
HEAVIER ELEMENTS...ALTHOUGH STORMS ARE NOT EXPECTED TO BE STRONG
OR SEVERE.
SHOWER AND THUNDERSTORM ACTIVITY WILL DIMINISH SATURDAY NIGHT WITH
THE WAVE PASSAGE AND DIURNAL STABILIZATION. INCREASING
NORTHWESTERLY FLOW BEHIND THE WAVE ON SUNDAY WILL HELP TO LIMIT
SHOWER AND THUNDERSTORM ACTIVITY DESPITE THE CYCLONIC FLOW ALOFT.
THUS EXPECTING A MAINLY DRY DAY ON SUNDAY...BUT WONT RULE OUT AN
ISOLATE SHOWER OR THUNDERSTORM BY THE AFTERNOON...ESPECIALLY NEAR
THE MOUNTAINS. ANOTHER WEAK SHORTWAVE MAY BE ON TRACK FOR
MONDAY...BUT MODELS DISAGREE ON THE TRACK/INTENSITY OF THE WAVE.
THE GFS REMAINS THE DRY SOLUTION...WHILE THE EC REMAINS FAIRLY
WET. THIS WILL BE AN IMPORTANT FEATURE TO WATCH FOR HOW IT WILL
IMPACT WEATHER ON LABOR DAY.
CHURCH
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
MODELS WERE IN PRETTY GOOD AGREEMENT THROUGH THE END OF NEXT
WEEK. THE FLOW BACKS TO THE WEST TUESDAY AND SOUTHWEST WEDNESDAY.
THIS WILL BE A MAINLY DRY PATTERN WITH WARMER TEMPERATURES. AN
UPPER TROUGH SLIDES ACROSS NORTHERN MONTANA AND SPLITS WEDNESDAY
NIGHT AND THURSDAY. TAIL END OF THE WAVE MOVES ACROSS THE AREA FOR
A CHANCE OF SHOWERS AND THUNDERSTORMS. A COLD FRONT WILL MOVE
THROUGH WEDNESDAY NIGHT AND PROVIDE COOLER TEMPERATURES FOR
THURSDAY AND FRIDAY. SOUTHWEST FLOW TAKES OVER FOR FRIDAY INTO
NEXT WEEKEND BUT HEIGHTS WERE ON THE LOW SIDE...SO TEMPERATURES
WILL REMAIN SLIGHTLY BELOW SEASONAL AVERAGES. THE GFS WAS MORE
AGGRESSIVE IN BUILDING HEIGHTS ON FRIDAY AND THEREFORE WARMER SO
WILL NEED TO BE MONITORED. WILL KEEP LOW POPS FOR THURSDAY AND
FRIDAY WITH SOUTHWEST FLOW AND WEAK WAVES MOVING THROUGH. TWH
&&
.AVIATION...
ISOLATED SHOWERS/TSTMS WILL IMPACT THE WESTERN MOUNTAINS AND
FOOTHILLS THROUGH THE REMAINDER OF THE EVENING. SHOWER AND ISOLD
TSTM ACTIVITY WILL INCREASE WEST OF KBIL LATER TONIGHT AS A
DISTURBANCE APPROACHES FROM THE WEST...WITH LOCAL MVFR AND
OCCASIONAL MOUNTAIN OBSCURATIONS. ON SATURDAY...SHOWERS AND TSTMS
WILL IMPACT THE ENTIRE AREA...WITH AREAS OF MVFR CONDITIONS AND
FREQUENT MOUNTAIN OBSCURATIONS.
&&
.PRELIMINARY POINT TEMP/POPS...
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 057/073 054/070 051/070 050/078 052/077 051/072 047/068
16/T 62/W 12/T 11/U 01/U 22/T 33/T
LVM 052/071 044/068 044/068 044/078 045/077 046/072 046/067
27/T 62/W 22/T 21/U 02/T 22/T 33/T
HDN 055/076 053/072 052/071 051/080 052/080 053/075 051/072
04/T 52/T 12/T 11/U 01/U 22/T 33/T
MLS 057/079 055/073 052/072 052/080 054/080 053/075 050/071
03/T 42/T 12/T 11/U 01/U 22/T 33/T
4BQ 057/084 055/070 052/071 051/080 053/082 054/076 053/074
03/T 43/T 12/T 11/U 01/U 22/T 33/T
BHK 053/078 053/071 048/071 049/078 051/078 052/074 053/070
04/T 52/T 13/T 11/U 01/U 23/T 33/T
SHR 052/080 050/070 047/070 045/080 048/080 050/075 049/072
03/T 53/T 22/T 21/U 01/U 22/T 33/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
855 PM MDT Fri Aug 29 2014
.DISCUSSION...
Update forthcoming. Have made some minor adjustments to the PoP
grids for the remainder of tonight. Water vapor and IR satellite
imagery clearly show upper trof position as it approaches western
Montana. Showers and isolated thunderstorms have developed out ahead
of the trof and these continue to move across southwest Montana.
This precipitation should increase in areal coverage after midnight
and begin spreading north and east as noted by the latest RUC and
HRRR analysis. Wet and unsettled morning continues to look on track.
Temperatures look reasonable.
&&
.AVIATION...
UPDATED 2340Z.
A weather disturbance and cold front will move through the area
Saturday morning. Showers will develop ahead of the cold front over
southwest and central Montana late tonight then continue into
Saturday morning as the disturbance and cold front move through.
During the afternoon expect more showers and a few thunderstorms
near and south of a KLWT to KHLN line with scattered showers north
to near U.S. route 2. As mentioned in the previous discussion expect
generally VFR conditions with the showers/thunderstorms although can
not rule out local MVFR conditions. Blank
&&
.PREV DISCUSSION...Issued 250 PM MDT Fri Aug 29 2014
Tonight through Sunday...Isolated showers and thunderstorm will
develop in far Southwest Montana this evening then increase in
coverage overnight. Showers and storms spread into Central Montana
by Saturday morning then continue on into Eastern Montana as an
associated upper wave moves east. A reinforcing trough swings into
the state during the afternoon with additional showers and
thunderstorms developing in Southwest and Central Montana through
the afternoon; however, only isolated showers are expected over my
northwestern zones. Conditions will improve overnight as the
trough axis moves eastward leaving a cool and slightly unsettled
airmass in place over the forecast area for Sunday. mpj
Sunday Night through Friday...Relatively quiet weather conditions
expected for first half of next week. A weak, quick-moving
shortwave trof will sweep across the state on Mon. GFS and GEM
forecast models indicate little, if any, precipitation with the trof
while the ECMWF continues to indicate broad coverage of showers
mainly over the southwest counties on Mon aftn/eve. Since a
northwest flow pattern aloft (like we`ll have on Mon) usually will
generate isolated showers with even minimal moisture and
instability, have kept in a slight chance of rain showers over the
astern third of the forecast area on Mon. Weak, transient high
pressure ridging will make for dry conditions from Tues through Wed,
with slightly warmer high temperatures (low to mid 70s) as winds
aloft transition to westerly. Stronger shortwave trof is forecast
to arrive on Thurs, though model solutions still showing some marked
run-to-run differences on the shortwave`s timing and precipitation
coverage for Thurs and Fri. General model consensus is that most of
the precipitation will occur Thur eve through midday Fri, behind a
surface cold front that tracks across the region on Thurs morning.
Some locations, especially along/south of a Helena-Lewistown line
may see rainfall totals of 0.25-0.50 inch, with lighter amounts
further north. The front will also usher in a cooler Canadian
airmass and bring snow levels down to the 6500-7500 ft range over
the central mountains and the Rocky Mtn Front.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 56 73 48 69 / 20 50 10 10
CTB 53 71 46 67 / 0 20 10 10
HLN 56 73 47 70 / 40 60 20 10
BZN 49 70 44 66 / 40 70 40 10
WEY 43 61 35 57 / 40 80 50 10
DLN 51 69 45 65 / 50 70 40 10
HVR 55 76 49 73 / 0 50 10 0
LWT 53 72 48 67 / 20 60 20 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS HASTINGS NE
352 PM CDT THU AUG 28 2014
.SHORT TERM...(THIS EVENING THROUGH TONIGHT)
ISSUED AT 309 PM CDT THU AUG 28 2014
THE PRIMARY FORECAST CONCERN THROUGH TONIGHT WILL ONCE AGAIN
CENTER AROUND THE CHANCE OF THUNDERSTORMS...LOCALLY HEAVY
RAINFALL...AND POSSIBLE FLOODING. SHOWERS AND THUNDERSTORMS SHOULD
BE LESS WIDESPREAD AND OVERALL LESS HEAVY THAN WHAT WE SAW LAST
NIGHT. THE PRIMARY TRIGGERING MECHANISM CONTINUES TO BE AN UPPER
LEVEL TROUGH THAT HAS VERY SLOWLY BEEN SLIDING EAST ACROSS
NEBRASKA. THE 500 MB TROUGH AXIS WILL EVENTUALLY SLIDE EAST INTO
OUR CWA BY DAWN. AS LONG AS WE ARE OUT AHEAD OF THIS TROUGH AXIS
WE WILL SEE AT LEAST SOME CHANCE OF SHOWERS AND
THUNDERSTORMS...WHICH WILL BE THE CASE THROUGH THE NIGHT.
THE 18Z NAM AND A RUN OR TWO OF THE HRRR ARE NOW HINTING AT THE
POSSIBILITY OF SOME ELEVATED THUNDERSTORMS FORMING WITHIN A FEW
HOURS AFTER SUNSET AROUND HIGHWAY 281 OR A LITTLE EAST OF HIGHWAY
281. IF THESE STORMS FORM THEY WILL TRACK NORTHEAST AND COULD BE
HEAVY RAIN PRODUCERS WITH AN OUTSIDE CHANCE OF A LOW END SEVERE
HAIL OR WIND EVENT. INSTABILITY HAS BEEN RATHER LOW TODAY DUE TO
THE EXTENSIVE CLOUD COVER...WHICH IS THE PRIMARY LIMITING FACTOR
FOR SEVERE POTENTIAL. IN ADDITION...THE DEEP LAYER WIND SHEAR IS
ONLY AROUND 30 KTS...WHICH IS WEAK TO MODEST AND CERTAINLY NOT
OVERLY IMPRESSIVE FOR SEVERE POTENTIAL. THEREFORE...GIVEN A FAIRLY
SIMILAR MOIST ENVIRONMENT TO LAST NIGHT BEING LOCATED OUT AHEAD OF
THE UPPER TROUGH...WITH JUST A BIT LESS LIFT OUR PRIMARY CONCERN
WILL REALLY CONTINUE TO BE HEAVY RAIN...BUT JUST LIKELY NOT AS
WIDESPREAD AS THE OTHER NIGHT. THE GROUND IS VERY SATURATED ACROSS
PRETTY MUCH OUR ENTIRE FORECAST AREA SO ANY HEAVY RAIN WILL RESULT
IN RUNOFF AND POSSIBLE FLOODING. AM MOST CONCERNED FOR THE AREA
ALONG AND EAST OF HIGHWAY 281 BASED ON THE LATEST 18Z NAM.
OVERALL...THE PROBABILITY OF RAIN IS LOWER TONIGHT THAN LAST
NIGHT GIVEN THAT THE COVERAGE AREA WILL BE LESS AND IT IS HARD TO
PIN POINT EXACTLY WHERE THE THUNDERSTORMS WILL DEVELOP WITHIN THE
MORE BROAD FAVORABLE ZONE.
.LONG TERM...(FRIDAY THROUGH THURSDAY)
ISSUED AT 309 PM CDT THU AUG 28 2014
FORECAST FOCUS IS ON THE CHANCES OF STORMS FRIDAY AND THEN CHANCES
OF SEVERE STORMS ON SUNDAY.
MODELS ARE IN GOOD AGREEMENT WITH MOVING AND TIMING OF MAJOR
FEATURES AT LEAST THROUGH MONDAY. IN GENERAL THE ATMOSPHERE IS
FORECAST TO MORPH FROM A CUTOFF LOW PATTERN BACK TO A MORE ZONAL
FLOW...SO OUT OF A HEAVY RAIN PATTERN AND BACK INTO A SEVERE WEATHER
TYPE REGIME.
THE LOW PRESSURE AREA THAT HAD BEEN PARKED OVER THE CENTRAL ROCKIES
THE LAST SEVERAL DAYS WILL EJECT EASTWARD ON FRIDAY AND LEAVE DRY
WEATHER BEHIND. AS IT MOVES THROUGH THERE WILL BE A THREAT OF
STORMS...BUT MAINLY OVER THE EASTERN THIRD OF THE AREA ON FRIDAY
AFTERNOON AND EARLY EVENING.
A RIDGE BUILDS OVER THE AREA ON SATURDAY BRINGING THE FIRST DRY AND
WARM DAY IN QUITE A WHILE. LOW CHANCES OF STORMS ARE BACK IN THE
FORECAST FOR SATURDAY NIGHT AND SUNDAY MORNING WITH A WEAK WAVE
MOVING ACROSS THE AREA.
HOWEVER...THE CHANCE OF STORMS FROM MID DAY SUNDAY INTO THE EVENING
IS MORE IMPRESSIVE. A COLD FRONT AND FAIRLY STRONG MID LEVEL WAVE
MOVE THROUGH DURING THAT TIME FRAME. MOST MODELS ARE IN AGREEMENT
WITH THE THE TIMING AN STRENGTH OF THE SYSTEM. THE STRONG
INSTABILITY AND GOOD SHEAR ARE MORE COMMON FOR MAY THAN AUGUST. SO
THERE IS A THREAT OF DAMAGING WINDS AND LARGE HAIL WITH STORMS THAT
DEVELOP. AS WITH ANY FORECAST OF CONVECTION SO MANY DAYS OUT THE
MODELS WILL LIKELY CHANGE...SO WE WILL CONTINUE TO MONITOR IT.
AS FOR THE WORK WEEK (MONDAY THROUGH THURSDAY)...OVERALL...MUCH
DRIER THAN THIS LAST WEEK...BUT HARD TO RULE OUT A HIT AND MISS
AFTERNOON AND EVENING STORM ESPECIALLY MONDAY...BUT THE MODELS ARE
STILL WAFFLING WITH TIMING AND STRENGTH OF FEATURES SO WILL LEAVE
DRY OR LOW PROBABILITIES UNTIL OUR CONFIDENCE RISES MORE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 117 PM CDT THU AUG 28 2014
THIS IS A DIFFICULT FORECAST PERIOD WITH CEILINGS BOUNCING AROUND
BETWEEN VFR AND MVFR THIS AFTERNOON AND THEN A CHANCE OF SHOWERS
AND THUNDERSTORMS. HOWEVER...THE PRECIPITATION CHANCES HAVE COME
DOWN SOME WITH STORMS BEING LESS WIDESPREAD THAN IN RECENT DAYS.
WILL SEE A SFC TROUGH AXIS TRACK THROUGH THIS EVENING INTO
TONIGHT...WHICH WILL RESULT IN LIGHT WINDS THAT COULD BE RATHER
VARIABLE.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...WESELY
LONG TERM...EDDY
AVIATION...WESELY
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1035 PM EDT FRI AUG 29 2014
.SYNOPSIS...A FRONT WILL REMAIN QUASI-STATIONARY OVER SOUTHEASTERN
NC TONIGHT...THEN RETREAT NORTHEASTWARD ACROSS CENTRAL AND EASTERN
NC AND VA ON SATURDAY.
&&
.NEAR TERM /TONIGHT/...
AS OF 1030 PM FRIDAY...
TWO PRIMARY FORECAST CONCERNS FOR TONIGHT INVOLVE THE DEVELOPMENT OF
LOW STRATUS AND FOG...AND SHOWERS.
THE FORMER HAS A HIGHER PROBABILITY OF OCCURRENCE OWING TO A REGIME
OF ABUNDANT LOW LEVEL MOISTURE - CHARACTERIZED BY SFC DEWPOINTS IN
THE UPPER 60S TO MIDDLE 70S - THAT HAS POOLED INVOF THE FRONT
STALLED OVER SE NC...AND WHICH HAS SINCE BECOME TRAPPED IN THE
VERTICAL BY A SHALLOW INVERSION. LIGHT TO CALM SFC WIND AND
ASSOCIATED COOLING OF THE BOUNDARY LAYER...IN BETWEEN PERCOLATING
PATCHES OF 2-6 THOUSAND FT CLOUDINESS...SHOULD THEN SUPPORT THE
DEVELOPMENT AND EXPANSION OF LOW CLOUDS AND FOG. THE HRRR SUGGESTS
SOME FOG MAY BECOME DENSE IN PATCHES OVER THE SOUTHERN AND WESTERN
PIEDMONT...WHERE SFC WINDS HAVE BEEN...AND WILL CONTINUE TO
BE...RELATIVELY LIGHTER.
THE PROBABILITY OF SHOWERS IS LESS CERTAIN. THERE IS A QPF SIGNAL
FOR SHOWER DEVELOPMENT OVER THE NORTHERN PIEDMONT PER NEAR TERM
GUIDANCE FROM BOTH THE HRRR AND RUC...BUT FORCING FOR ASCENT AND
INSTABILITY TO DRIVE SUCH DEVELOPMENT...ARE EXPECTED TO BE VERY
WEAK. THE FORCING FOR ASCENT WILL COME COURTESY OF WEAK AND SHALLOW
ISENTROPIC UPGLIDE ATOP THE AFOREMENTIONED STALLED SFC FRONT
TONIGHT...AND RECENT REGIONAL VWP WINDS CORROBORATE THIS IDEA WITH
THEIR DEPICTION OF WEAK BUT VEERING WINDS IN THE LOWEST SEVERAL
THOUSAND FT. WILL INTRODUCE JUST A SLIGHT CHANCE OF A SHOWER
GENERALLY NORTH OF HIGHWAY 64 TO ACCOUNT FOR THIS POSSIBILITY.
LOWS GENERALLY 69 TO 75.
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 250 PM FRIDAY...
CENTRAL NC WILL REMAIN UNDER THE INFLUENCE OF AN UPPER LEVEL RIDGE
ON SATURDAY. THE LINGERING BACKDOOR FRONT IS EXPECTED TO WASH OUT
DURING THE DAY AS THE SURFACE HIGH SHIFTS OFFSHORE AND A LIGHT
SOUTHERLY RETURN FLOW DEVELOPS ACROSS THE REGION. ALL OF THIS WILL
RESULT IN A TYPICAL SUMMERTIME PATTERN...WITH HIGHS RISING INTO THE
LOWER 90S. WITH MARGINAL INSTABILITY EXPECTED TO DEVELOP (HIGHEST
ACROSS THE SOUTHEAST)...ISOLATED DIURNAL CONVECTION WILL BE
POSSIBLE...ALTHOUGH MANY AREA LIKELY REMAINING DRY. OVERNIGHT LOWS
ARE EXPECTED TO BE IN THE UPPER 60S TO LOWER 70S.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
AS OF 250 PM FRIDAY...
SHORTWAVE ENERGY ORIGINATING FROM THE WESTERN GULF OF MEXICO AND
ASSOCIATED TROPICAL MOISTURE PLUME WILL TRACK NORTHWARD INTO THE TN
AND OHIO VALLEY ON SUNDAY AND THEN NORTHEASTWARD INTO THE MID-
ATLANTIC STATES ON MONDAY. SUBTROPICAL RIDGE CENTERED OVER THE
SOUTHEAST COAST SHOULD INITIALLY DEFLECT THE BETTER RAIN CHANCES
WEST OF THE AREA THROUGH SUNDAY(VIA RING OF FIRE MOISTURE RETURN
CONVECTION PATTERN ACROSS THE NC MTNS AND FOOTHILLS). HOWEVER BY
MONDAY...UPPER RIDGE AXIS BEGINS TO DEAMPLIFY IN RESPONSE TO THE
AFOREMENTIONED SHORTWAVE MOVING THROUGH THE MID-ATLANTIC REGION WITH
MID/UPPER LEVEL SHEAR AXIS AND LEE SIDE THERMAL TROUGH PROVIDING
SUFFICIENT FORCING TO SUPPORT ISOLATED TO SCATTERED CONVECTION
MONDAY AFTERNOON AND EVENING.
EXPECT A TYPICAL SUMMERTIME PATTERN THROUGH MID TO LATE WEEK AS
SUBTROPICAL RIDGE AXIS SHIFTS WESTWARD INTO THE MID SOUTH-LOWER MS
VALLEY...ALLOWING FOR ISOLATED TO WIDELY SCATTERED STORMS TO FIRE
ALONG LEE SIDE THERMAL TROUGH EACH AFTERNOON. HIGHS IN THE UPPER 80S
TO LOWER 90S WITH LOWS IN THE UPPER 60S T0 LOWER 70S.
MODELS CONTINUE TO DELAY THE ARRIVAL OF A BACK-DOOR COLD FRONT INTO
THE AREA...WITH LATEST TIMING NOW SUGGESTING THURSDAY NIGHT AND INTO
FRIDAY.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 819 PM FRIDAY...
CONDITIONS HAVE IMPROVED TO VFR AT ALL TERMINALS THIS EVENING. IFR
CONDITIONS WILL RETURN TO THE AREA OVERNIGHT... AS A FRONTAL
BOUNDARY REMAINS ACROSS THE AREA... WITH HIGH LOW LEVEL MOISTURE AND
LIGHT WIND. CONDITIONS WILL IMPROVE AFTER SUNRISE... AND RETURN TO
VFR DURING THE DAY SATURDAY AS THE BOUNDARY DISSIPATES.
OUTLOOK...A SUMMERTIME PATTERN WILL PERSIST THROUGH EARLY/MID NEXT
WEEK...WITH ISOLATED TO SCATTERED AFTERNOON/EVENING CONVECTION AND A
POTENTIAL FOR EARLY MORNING FOG/STRATUS.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...KRD
LONG TERM...CBL
AVIATION...SEC/KRD
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1010 PM CDT FRI AUG 29 2014
.UPDATE...
ISSUED AT 1008 PM CDT FRI AUG 29 2014
NOT UNEXPECTED...BUT CLEARING HAS SLOWED A BIT JUST A TAD SLOWER
THAN EARLIER RAP MODEL INDICATED. THUS BACKED OFF A LITTLE IN THE
GRIDS WITH TIMING. AVIATION TAFS APPEAR OK. DID ADD PATCHY FOG TO
DVL REGION AS GOOD RADIATIONAL COOLING WILL OCCUR THERE.
SURROUNDING OFFICES HAVE FOG MENTIONED AND DONT SEE ENOUGH OF AN
IN ISSUE AS CLEARING WILL ONLY SLOWLY PROGRESS SOUTH OVERNIGHT.
TEMPS OK. RADAR SHOWS A FEW SPRINKLES LEFTOVER AROUND BEMIDJI-
FOSSTON SO KEPT ISOLD -RW TIL 05Z IN THAT AREA.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 255 PM CDT FRI AUG 29 2014
CURRENT METARS SHOW THE SFC BNDRY MOVING ACROSS ND TODAY IS
LOCATED ROUGHLY OVER THE RED RIVER VALLY FROM HCO (MN) TO FAR.
SAT CONTINUING TO SHOW SKIES OVER THE UPPER SHEYENNE BASIN AND
JAMES VALLEY REGION BREAK UP. CURRENT RADAR SHOWS A SMALL CLUSTER
OF RAIN SHOWERS/VIRGA OVER CENTRAL ND. IMMEDIATE SHORT TERM MODELS
APPEAR TO BE OVERDOING PRECIP...SO WILL GO MOSTLY WITH
CONTINUITY/WX TRENDS VS ANY MODEL CHOICE. LATER IN THE PERIOD A
FRONT MOVES INTO WRN ND...WITH GFS FASTER THAN THE ECMWF ON
TIMING. WILL USE A FCST BLEND FOR THIS PD.
THIS AFTN AND TONIGHT....SFC BNDRY NOW EAST OF AREA OF CLEARING
AND MOVING INTO MN...WHERE SKIES HAVE BEEN CLOUDY ALL DAY AND
REGION HAS NOT HEATED OUT. OVERALL NOT AN IMPRESSIVE SITUATION AND
WILL KEEP IN THE LOW CHANCE POPS WITH RAIN SHOWERS AND ISOLD TSTMS
THE MAIN THREAT. COOLEST AREAS TONIGHT WILL BE ACROSS EASTERN ND
AND INTO FAR NWRN MN WHERE SKIES WILL LIKELY CLEAR AND TEMPS COULD
DROP INTO UPPER 40S ACROSS THIS REGION.
TOMORROW AND TOMORROW NIGHT...SHORT WAVE RIDGE ALOFT WILL BRING DRY
WEATHER TO THE REGION...HOWEVER A STRONG UPPER WAVE OVER PAC NW
WILL MOVE INTO MT WHILE LOW PRESSURE DEVELOPS OVER THE PLAINS. AN
OPEN GULF WILL ALLOW STRONG H850 MOISTURE FLUX INTO THE REGION BY
SATURDAY NIGHT. EXPECT SOME ELEVATED CONVECTION TO PICK UP BY LATE
SAT EVENING AND INCREASE AFT MIDNIGHT. HAVE LIKELY POPS INTO THE
WRN ZONES AFT 06Z...HOWEVER MAIN SHOW WILL BE DRG THE DAY SUNDAY
(SEE LONG RANGE DISCUSSION) AS SFC FRONT MOVES ACROSS DAKOTAS AND
INTO MN.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 255 PM CDT FRI AUG 29 2014
SUN AND SUN NIGHT...MODELS INDICATING EXTENDED AREA OF SFC
TROUGHING/FRONT FROM EASTERN DAKOTAS DOWN THROUGH SD/NE AND INTO
NW KS. SHORT WAVE PROGGED TO BE ENTERING WRN DAKOTAS FROM EASTERN
MT AT 12Z SUNDAY. GFS IS FASTER WITH THE UPPER WAVE ENTERING THE
DAKOTAS THAN IS THE ECMWF...AND ITS TIMING WILL BE CRITICAL ON SVR
POTENTIAL FOR SUN AFTN. GULF MOISTURE SHOULD BE READILY AVAILABLE
WITH BOTH MODELS SHOWING STRONG H850 MOISTURE FLUX INTO THE
CENTRAL AND EASTERN DAKOTAS SAT NIGHT COUPLED WITH 35 TO 45 KTS OF
0-6 KM BULK SHEAR. ASSOCIATED SFC FRONT PROGGED TO ENTER THE
EASTERN DAKOTAS (WESTERN CWA) LATE SUN MORNING AND MOVE ACROSS THE
VALLEY IN THE EARLY AFTN HOURS...EXTENDING ACROSS NW AND W CNTRL
MN BY MID AFTN. BULK SHEAR BY SUN AFTN EXPECTED TO INCREASE TO 40
KTS TO 50 KTS. WITH THESE INGREDIENTS IN PLACE...THERE IS
CERTAINLY A POTENTIAL FOR SVR ACROSS MINNESOTA ON SUN AFTN. SPC
HAS ISSUED A SLIGHT RISK FOR DAY 3. CONVECTION SHOULD BEGIN
TAPERING OFF BY MIDNIGHT SUN NIGHT AND MONDAY WILL BE DRY ACROSS
MAJORITY OF THE AREA.
FOR MON NIGHT THROUGH FRIDAY...THE PERIOD SHOULD START OUT MAINLY
DRY. THE CHANCES FOR SHOWERS AND SOME STORMS COULD INCREASE BY THE
MIDDLE TO END OF NEXT WEEK...WITH MORE CYCLONIC FLOW ALOFT
TRANSITIONING TO POTENTIAL SW FLOW ALOFT. THE EXACT TIMING OF
SHORTWAVES IS TOUGH...BUT WILL LEAVE IN MENTION OF MAINLY CHANCE
TYPE POPS FOR THE END OF NEXT WEEK...WITH THE DEEPER MOISTURE AND
SOME INSTABILITY CONFINED MAINLY TO THE SOUTHERN 2/3 OF THE FORECAST
AREA.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 642 PM CDT FRI AUG 29 2014
MONITORING WIND SHIFT WITH NORTH-NORTHWEST WINDS INTO FARGO AND
WILL BE INTO BEMIDJI SOON. NORTH WINDS 15 TO 25 KTS AT GFK WITH
LIGHTER WINDS NOW AT DVL AND TVF. ALL WINDS WILL DIMINISH ONCE
FRONT PUSHES THROUGH AND HIGH PRESSURE SETTLES INTO NORTH CENTRAL
ND OVERNIGHT. MVFR CIGS PRESENT NEAR AND JUST BEHIND FRONT FOR A
FEW HOURS WITH LOW END VFR CIGS IN THE 3-5K FT RANGE AHD OF FRONT
AND ON TRAILING EDGE OF CLOUD DECK BEFORE CLEARING MOVES IN.
TIMING OF CLEARING KEPT ABOUT THE SAME AS PREV FCST...02Z
DVL/06-7Z GFK/10Z TVF/12-15Z FAR-BJI. GIVE OR TAKE A LITTLE BIT.
SATURDAY WILL SEE VFR CONDITIONS WITH JUST A FEW CLOUDS OVER MUCH
OF THE REGION...THOUGH CLOUDS WILL HOLD A BIT LONGER IN WCNTRL MN
INTO SATURDAY.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...RIDDLE
SHORT TERM...SPEICHER
LONG TERM...DK/SPEICHER
AVIATION...RIDDLE
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1259 PM CDT THU AUG 28 2014
.UPDATE...
ISSUED AT 1259 PM CDT THU AUG 28 2014
ONLY SIGNIFICANT UPDATE WAS TO CLEAN UP SKY COVER...TRYING TO GET
A BETTER PICTURE OF WHERE SKIES WERE CLOUDY VS. CLEAR. CURRENT
FORECAST HIGH TEMPERATURES LOOK GOOD WITH LOWER 70S SOUTHEAST TO
AROUND 90 NORTHWEST.
UPDATE ISSUED AT 1017 AM CDT THU AUG 28 2014
MADE SOME MINOR UPDATES TO POPS IN THE SOUTHEAST CWA AND ADJUSTED
SKY COVER BASED ON RADAR.
LATEST RAP FORECAST SOUNDINGS ARE SHOWING LIMITED INSTABILITY OVER
THE SOUTHEAST...THUS HAVE DROPPED THE MENTION OF THUNDER. WILL
TAKE A CLOSER LOOK AT TEMPERATURES LATE MORNING/EARLY AFTERNOON.
CLOUD SHIELD MIGHT HOLD TEMPERATURES BACK SOUTHEAST...BUT
ESPECIALLY THE WESTERN EDGE OF THE CLOUD SHIELD WOULD STILL HAVE A
GOOD SHOT OF REACHING FORECAST HIGHS AS WE GOT A WARM START.
UPDATE ISSUED AT 634 AM CDT THU AUG 28 2014
UPPER LOW BRUSHING BY SOUTHERN NORTH DAKOTA TODAY. RADAR AND
SURFACE REPORTS SHOW PRECIPITATION ACROSS NORTH CENTRAL SOUTH
DAKOTA. THIS AREA WILL BE ENTERING SOUTH CENTRAL/SOUTHEAST NORTH
DAKOTA THIS MORNING. AREAS OF FOG CONTINUE MAINLY FAR SOUTHWEST AND
NORTH CENTRAL. CURRENT FORECAST TRENDING WELL.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT THU AUG 28 2014
NEAR TERM CONCERNS/EARLY THIS MORNING...IS LOCALIZED DENSE FOG AT
HETTINGER. HAVE NOT SEEN MUCH EXPANSION IN THIS AREA PER SURFACE
OBS AND FOG/STRATUS LOOP...THUS WILL LIKELY UTILIZE A SHORT TERM
FORECAST TO COVER THIS. MID LEVEL CLOUDS EJECTING ACROSS WESTERN
SOUTH DAKOTA MAY BE ENOUGH TO HALT RADIATIONAL COOLING AND IMPROVE
VISIBILITIES AT HETTINGER. ANOTHER EARLY MORNING CONCERN IS THE
DEVELOPMENT OF SHOWERS IN FAR SOUTH CENTRAL AND INTO THE JAMES
RIVER VALLEY. LOCAL/REGIONAL RADAR SHOWS A LARGE SWATH OF SHOWERS
AND ISOLATED THUNDERSTORMS SLOWLY EDGING NORTH WITH TIME FROM
SOUTH DAKOTA.
FOR TODAY...MAIN CHANGE IN THE FORECAST WAS TO INCREASE POPS INTO
THE LIKELY AND CATEGORICAL RANGE ACROSS THE SOUTHERN JAMES RIVER
VALLEY. ALL MODEL SOLUTIONS PEG THE SOUTHEAST WITH AT LEAST A
THIRD OF AN INCH OF RAIN...POSSIBLY EVEN HIGHER AMOUNTS...DURING
THE MORNING AND INTO MID AFTERNOON. CURRENT RAINFALL AMOUNTS IN
PIERRE SOUTH DAKOTA WOULD SUPPORT THIS WITH 0.26 INCHES REPORTED
IN A 3HR PERIOD. ENOUGH INSTABILITY PER NAM/GFS PARAMETERS AND SPC
TO WARRANT A MENTION OF ISOLATED THUNDERSTORMS. LATEST WATER VAPOR
IMAGERY SHOWS A POTENT SHORTWAVE OVER CENTRAL SOUTH DAKOTA. THIS
IS FORECAST TO SHIFT INTO THE SOUTHERN JAMES RIVER VALLEY BY 18Z
WITH STRONG VERTICAL MOTION PER H85-H3 OMEGA FIELD. GIVEN THE
EXTENSIVE COVERAGE OF SHOWERS IN SOUTH DAKOTA CURRENTLY...AND
EXCELLENT MODEL AGREEMENT ON AREAL COVERAGE AND DURATION...HAVE HIGH
CONFIDENCE WITH LIKELY/CATEGORICAL POPS IN THE SOUTHEAST. POPS
QUICKLY TAPER OFF TO THE WEST AND NORTH WITH A TRANSITION TOWARD A
A MOSTLY SUNNY SKY ELSEWHERE. WENT WITH THE COOLER NAM/GFS MOS
TEMPERATURES IN THE SOUTHEAST WITH CLOUDS AND SHOWERS PERSISTING
THROUGH THE DAY...THUS HIGHS WILL ONLY REACH THE LOWER 70S. CONTRAST
THIS TO THE FAR WEST WHERE HIGHS WILL REACH 90 DEGREES AT WILLISTON.
THIS WARMING IN THE FAR WEST IS ALSO AHEAD OF AN ADVANCING COLD
FRONT WHICH WILL MOVE ACROSS THE NORTHWEST THURSDAY EVENING...AND
INTO CENTRAL NORTH DAKOTA AFTER MIDNIGHT. MODEL CONSENSUS IS FOR A
DRY FROPA OVERNIGHT WITH INCREASING POPS AFTER THE SHORT TERM PERIOD.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 315 AM CDT THU AUG 28 2014
INITIALLY...A COLD FRONT ASSOCIATED WITH A WEAK SHORTWAVE TROUGH
WILL BE MOVING THROUGH THE STATE FRIDAY MORNING. THE GFS/ECMWF
APPEAR TO BE THE MOST ROBUST WITH PF ALONG AND BEHIND THE FRONT
ACROSS SOUTHWEST NORTH DAKOTA. WILL FOCUS ON THE SOUTHWEST AND
EVENTUALLY SOUTH CENTRAL NORTH DAKOTA FOR SCATTERED TO WIDELY
SCATTERED THUNDERSTORMS. THIS WILL BE FOLLOWED BY A FAIRLY DRY
PERIOD FRIDAY NIGHT AND SATURDAY IN WEAK SUBSIDENCE BEHIND THE
SHORTWAVE TROUGH AND THE NEXT MORE SIGNIFICANT UPPER LOW DUE IN
SATURDAY AFTERNOON AND NIGHT. MODELS SEEM TO PRETTY MUCH PEG A
LINE OF THUNDERSTORMS ALONG AND AHEAD OF THE SHORTWAVE TROUGH AND
ASSOCIATED FRONTAL BOUNDARY SATURDAY NIGHT. WITH MODEL AGREEMENT
SATURDAY NIGHT INTO SUNDAY MORNING FEEL CONFIDENT IN RAISING POPS
TO AT LEAST LIKELY WITH AN AREA OF CATEGORICAL ACROSS MUCH OF
CENTRAL NORTH DAKOTA. ON SUNDAY SUBSIDENCE BEHIND THE
COLD/OCCLUDED FRONT SHOULD BRING IN COOLER/DRIER AIR BUT CANNOT
RULE OUT WIDELY SCATTERED POST FRONTAL SHOWERS WITH COOL CYCLONIC
FLOW ALOFT. MONDAY THROUGH WEDNESDAY SEE MAINLY NORTHWEST FLOW
ALOFT WITH ISOLATED SHOWERS/THUNDERSTORMS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1259 PM CDT THU AUG 28 2014
MVFR CEILING AT KBIS AND IFR CEILING AT KJMS. KBIS SHOULD LIFT TO
VFR BY 20 UTC. JMS LIFTING TO MVFR EARLY AFTERNOON BUT COULD
REMAIN MVFR THOUGH LATE AFTERNOON. ONCE KJMS DOES CLEAR OUT
TONIGHT AS THE SYSTEM OVER THE PLAINS MOVES EAST...COULD SEE A
PERIOD OF POSSIBLE LOW CEILINGS AND FOG BEFORE A FRONTAL PASSAGE
FRIDAY MORNING. KBIS COULD ALSO SEE A RETURN OF LOW CLOUDS TONIGHT
UNTIL FRONT PASSES...BUT LESS CERTAIN HERE SO LEFT IT VFR FOR NOW.
KDIK...KISN AND KMOT EXPECTED TO REMAIN VFR WITH SOUTH TO
SOUTHWEST FLOW TURNING NORTH WITH CDFNT PASSAGE FRIDAY MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...KS
LONG TERM...WAA
AVIATION...TWH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1017 AM CDT THU AUG 28 2014
.UPDATE...
ISSUED AT 1017 AM CDT THU AUG 28 2014
MADE SOME MINOR UPDATES TO POPS IN THE SOUTHEAST CWA AND ADJUSTED
SKY COVER BASED ON RADAR.
LATEST RAP FORECAST SOUNDINGS ARE SHOWING LIMITED INSTABILITY OVER
THE SOUTHEAST...THUS HAVE DROPPED THE MENTION OF THUNDER. WILL
TAKE A CLOSER LOOK AT TEMPERATURES LATE MORNING/EARLY AFTERNOON.
CLOUD SHIELD MIGHT HOLD TEMPERATURES BACK SOUTHEAST...BUT
ESPECIALLY THE WESTERN EDGE OF THE CLOUD SHIELD WOULD STILL HAVE A
GOOD SHOT OF REACHING FORECAST HIGHS AS WE GOT A WARM START.
UPDATE ISSUED AT 634 AM CDT THU AUG 28 2014
UPPER LOW BRUSHING BY SOUTHERN NORTH DAKOTA TODAY. RADAR AND
SURFACE REPORTS SHOW PRECIPITATION ACROSS NORTH CENTRAL SOUTH
DAKOTA. THIS AREA WILL BE ENTERING SOUTH CENTRAL/SOUTHEAST NORTH
DAKOTA THIS MORNING. AREAS OF FOG CONTINUE MAINLY FAR SOUTHWEST AND
NORTH CENTRAL. CURRENT FORECAST TRENDING WELL.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT THU AUG 28 2014
NEAR TERM CONCERNS/EARLY THIS MORNING...IS LOCALIZED DENSE FOG AT
HETTINGER. HAVE NOT SEEN MUCH EXPANSION IN THIS AREA PER SURFACE
OBS AND FOG/STRATUS LOOP...THUS WILL LIKELY UTILIZE A SHORT TERM
FORECAST TO COVER THIS. MID LEVEL CLOUDS EJECTING ACROSS WESTERN
SOUTH DAKOTA MAY BE ENOUGH TO HALT RADIATIONAL COOLING AND IMPROVE
VISIBILITIES AT HETTINGER. ANOTHER EARLY MORNING CONCERN IS THE
DEVELOPMENT OF SHOWERS IN FAR SOUTH CENTRAL AND INTO THE JAMES
RIVER VALLEY. LOCAL/REGIONAL RADAR SHOWS A LARGE SWATH OF SHOWERS
AND ISOLATED THUNDERSTORMS SLOWLY EDGING NORTH WITH TIME FROM
SOUTH DAKOTA.
FOR TODAY...MAIN CHANGE IN THE FORECAST WAS TO INCREASE POPS INTO
THE LIKELY AND CATEGORICAL RANGE ACROSS THE SOUTHERN JAMES RIVER
VALLEY. ALL MODEL SOLUTIONS PEG THE SOUTHEAST WITH AT LEAST A
THIRD OF AN INCH OF RAIN...POSSIBLY EVEN HIGHER AMOUNTS...DURING
THE MORNING AND INTO MID AFTERNOON. CURRENT RAINFALL AMOUNTS IN
PIERRE SOUTH DAKOTA WOULD SUPPORT THIS WITH 0.26 INCHES REPORTED
IN A 3HR PERIOD. ENOUGH INSTABILITY PER NAM/GFS PARAMETERS AND SPC
TO WARRANT A MENTION OF ISOLATED THUNDERSTORMS. LATEST WATER VAPOR
IMAGERY SHOWS A POTENT SHORTWAVE OVER CENTRAL SOUTH DAKOTA. THIS
IS FORECAST TO SHIFT INTO THE SOUTHERN JAMES RIVER VALLEY BY 18Z
WITH STRONG VERTICAL MOTION PER H85-H3 OMEGA FIELD. GIVEN THE
EXTENSIVE COVERAGE OF SHOWERS IN SOUTH DAKOTA CURRENTLY...AND
EXCELLENT MODEL AGREEMENT ON AREAL COVERAGE AND DURATION...HAVE HIGH
CONFIDENCE WITH LIKELY/CATEGORICAL POPS IN THE SOUTHEAST. POPS
QUICKLY TAPER OFF TO THE WEST AND NORTH WITH A TRANSITION TOWARD A
A MOSTLY SUNNY SKY ELSEWHERE. WENT WITH THE COOLER NAM/GFS MOS
TEMPERATURES IN THE SOUTHEAST WITH CLOUDS AND SHOWERS PERSISTING
THROUGH THE DAY...THUS HIGHS WILL ONLY REACH THE LOWER 70S. CONTRAST
THIS TO THE FAR WEST WHERE HIGHS WILL REACH 90 DEGREES AT WILLISTON.
THIS WARMING IN THE FAR WEST IS ALSO AHEAD OF AN ADVANCING COLD
FRONT WHICH WILL MOVE ACROSS THE NORTHWEST THURSDAY EVENING...AND
INTO CENTRAL NORTH DAKOTA AFTER MIDNIGHT. MODEL CONSENSUS IS FOR A
DRY FROPA OVERNIGHT WITH INCREASING POPS AFTER THE SHORT TERM PERIOD.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 315 AM CDT THU AUG 28 2014
INITIALLY...A COLD FRONT ASSOCIATED WITH A WEAK SHORTWAVE TROUGH
WILL BE MOVING THROUGH THE STATE FRIDAY MORNING. THE GFS/ECMWF
APPEAR TO BE THE MOST ROBUST WITH PF ALONG AND BEHIND THE FRONT
ACROSS SOUTHWEST NORTH DAKOTA. WILL FOCUS ON THE SOUTHWEST AND
EVENTUALLY SOUTH CENTRAL NORTH DAKOTA FOR SCATTERED TO WIDELY
SCATTERED THUNDERSTORMS. THIS WILL BE FOLLOWED BY A FAIRLY DRY
PERIOD FRIDAY NIGHT AND SATURDAY IN WEAK SUBSIDENCE BEHIND THE
SHORTWAVE TROUGH AND THE NEXT MORE SIGNIFICANT UPPER LOW DUE IN
SATURDAY AFTERNOON AND NIGHT. MODELS SEEM TO PRETTY MUCH PEG A
LINE OF THUNDERSTORMS ALONG AND AHEAD OF THE SHORTWAVE TROUGH AND
ASSOCIATED FRONTAL BOUNDARY SATURDAY NIGHT. WITH MODEL AGREEMENT
SATURDAY NIGHT INTO SUNDAY MORNING FEEL CONFIDENT IN RAISING POPS
TO AT LEAST LIKELY WITH AN AREA OF CATEGORICAL ACROSS MUCH OF
CENTRAL NORTH DAKOTA. ON SUNDAY SUBSIDENCE BEHIND THE
COLD/OCCLUDED FRONT SHOULD BRING IN COOLER/DRIER AIR BUT CANNOT
RULE OUT WIDELY SCATTERED POST FRONTAL SHOWERS WITH COOL CYCLONIC
FLOW ALOFT. MONDAY THROUGH WEDNESDAY SEE MAINLY NORTHWEST FLOW
ALOFT WITH ISOLATED SHOWERS/THUNDERSTORMS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1017 AM CDT THU AUG 28 2014
IFR CEILINGS CONTINUE AT KBIS AND KJMS AND SHOULD LIFT TO MVFR
LATE MORNING TO EARLY AFTERNOON. COULD SEE MVFR HOLD ON THROUGH
MID AFTERNOON...ESPECIALLY AT KJMS. VFR CONDITIONS EXPECTED AT
KDIK-KISN-KJMS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...KS
LONG TERM...WAA
AVIATION...TWH
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
700 AM CDT THU AUG 28 2014
.UPDATE...
ISSUED AT 655 AM CDT THU AUG 28 2014
NO SIG UPDATES PLANNED THIS EARLY MORNING. RADAR SHOWS ISOLATED
WEAK RETURNS /POSSIBLE VIRGA/ IN THE AREA WITH ORGANIZED
CONVECTION JUST BEGINNING TO MOVE INTO SOUTHCENTRAL ND ATTM.
LATEST RUC AND HRRR UPDATES TRENDING TO SOMEWHAT LESS ROBUST
CONVECTION INTO OUR AREA. REGIONAL RADAR LOOP SHOWS TWO MAIN AREAS
OF ORGANIZED DEEP CONVECTION... ONE ASSOCIATED WITH THE MAIN
SURFACE LOW IN SOUTHEAST SD AND THE OTHER ASSOCIATED WITH THE
DISTURBANCE MOVING NORTHEASTWARD THROUGH CENTRAL SD.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 340 AM CDT THU AUG 28 2014
TODAY AND TONIGHT...CONVECTION CONTINUES TO FIRE ACROSS WESTERN AND
CENTRAL SD IN ADVANCE OF A MID-LEVEL DISTURBANCE...NOW LIFTING
OUT OF THE SOUTHERN STREAM H5 TROF OVER SOUTHEAST COLORADO. BOTH
00Z AND 06Z NAM40 HAVE BEEN PRETTY AGGRESSIVE ON BRINGING THAT
INCREASED MOISTURE AND ENERGY INTO SOUTHEAST ND BY SUNRISE AND
OVER MOST OF THE AREA /ALG AND SOUTH OF HWY 2/ THROUGHOUT THE DAY.
MEANWHILE...MODELS ARE IN FAIR AGREEMENT ON BRINGING THE MAIN
SURFACE LOW CENTER INTO SOUTHEASTERN SD BY EARLY EVENING AND
ACROSS SOUTHERN MN LATER TONIGHT. WITH THAT... THE MAIN DEEP
MOISTURE PUSH SHOULD REMAIN FOCUSED WELL SOUTH OF THE RED RIVER
BASIN... THUS AM CURRENTLY DISCOUNTING THE HEAVIER PRECIP BULLS EYE
WHICH THE ROGUE 00Z GFS HAS TARGETED INTO THE SOUTHERN RED RIVER
BASIN AREA.
FRIDAY...AS CLOUDS DEPART THE WEST CENTRAL MN REGION DURING THE
EARLY MORNING WE CAN EXPECT INCREASING CLOUDS TO BEGIN DESCENDING
INTO THE AREA THROUGH NORTHEAST ND... AHEAD OF AN APPROACHING
NORTHERN STREAM COLD FRONT. SCATTERED SHOWERS AND THUNDERSTORMS
SHOULD ACCOMPANY THAT FEATURE DURING THE EARLY PART OF FRIDAY...
WITH SKIES RAPIDLY CLEARING BEHIND THE FRONT FROM NORTHWEST TO
SOUTHEAST BY LATE FRIDAY AFTERNOON AND EARLY EVENING.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 340 AM CDT THU AUG 28 2014
FAST AND FURIOUS IS THE WEEKEND.
FRIDAY NIGHT THROUGH SATURDAY...A COOL AND DRY FRIDAY NIGHT SHOULD
GIVE WAY TO A SUNNY AND DRY SATURDAY. EXPECT A SEASONABLY COOL
SURFACE HIGH PRESSURE CELL TO SLIP ACROSS THE AREA THROUGH
MIDDAY... WITH INCREASING SOUTHERLY WINDS BRINGING TEMPS BACK UP
TO NEAR SEASONAL NORMALS THROUGH LATE AFTERNOON. A FLATTENED AND
FAST H5 FLOW SHOULD HAVE THE NEXT STORM SYSTEM APPROACHING FROM
THE WEST LATE SATURDAY EVENING INTO THE OVERNIGHT.
SUNDAY THROUGH WEDNESDAY...LONG WAVE TROUGH SETTLES IN OVER WESTERN
NORTH AMERICA. ALSO A LONG WAVE TROUGH MOVE ACROSS SOUTHERN
CANADA BY THE END OF THE PERIOD. LNG WAVE RIDGE OVER THE SOUTHEAST
US BUILDS NORTH BY THE END OF THE PERIOD. THE GFS IS A LITTLE
FASTER AT THE BEGINNING OF THE PERIOD AND THE ECMWF BECOMES
SLIGHTLY FASTER BY THE END OF THE PERIOD. UPPER LEVEL JET IS SOUTH
OF THE AREA SUN AND MON. THEN SHIFTS NORTH OF THE AREA BY WED.
BOTH GFS AND ECMWF PRECIP ARE TRENDING MORE TO THE SOUTHEAST OVER
THE LAST COUPLE MODEL RUNS. WILL BLEND THE TWO MODELS.
LITTLE CHANGE TO TEMPS...A DEGREE OR SO LOWER ON SUN AND A DEGREE OR
TWO HIGH FOR TUE AND WED.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY NIGHT)
ISSUED AT 655 AM CDT THU AUG 28 2014
EXPECT INCREASING VFR CIGS INTO THE SOUTHERN AND CENTRAL RRV
THROUGH 16Z...WITH FAIR SKIES OVER FAR NORTHWEST MN. MID TO LOW
LEVEL CIGS WILL OVERSPREAD THE SOUTHERN TWO THIRDS OF THE FA
THROUGH THE DAYTIME WITH AREAS SHOWERS AND ISOLATED THUNDERSTORMS
MUCH OF THE DAY. LATE AFTERNOON AND EVENING HOURS WILL HAVE SCT
SKIES MOVG FROM EASTERN ND INTO NORTHWEST MN... WITH LINGERING
CLOUDS ACROSS THE FAR SOUTHEAST FA INTO THE OVERNIGHT. INCREASING
SOUTHERLY WINDS EXPECTED THROUGH THE DAY.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...GUST
SHORT TERM...GUST
LONG TERM...GUST/HOPPES
AVIATION...GUST
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1145 PM CDT WED AUG 27 2014
.UPDATE...
ISSUED AT 1140 PM CDT WED AUG 27 2014
NO CHANGE FROM THE PREVIOUS UPDATE.
UPDATE ISSUED AT 954 PM CDT WED AUG 27 2014
SOME POP CHANGES FROM NEIGHBORING OFFICES THIS EVENING...MAINLY TO
SLOW DOWN ADVANCE OF PRECIP CHANCES NORTHWARD INTO SE ND/WCNTRL
MN. WENT ALONG WITH CHANGES. AGREES WITH RADAR AND LATEST HRRR AS
WELL. MID LEVEL MOISTURE SPREADING EAST-NORTHEAST THRU SE ND AS
EXPECTED.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 305 PM CDT WED AUG 27 2014
NEXT CHANCE OF LIGHT RAIN WHICH ARRIVES LATER TONIGHT REMAINS THE
MAIN FORECAST CHALLENGE. MODELS HAVE BEEN BACK AND FORTH WITH THIS
FEATURE THE LAST COUPLE OF DAYS...ONE RUN PUSHING IT SOUTH OF THE
FA WHILE THE NEXT KEEPS IT THERE. TODAYS RUNS DO NOT ADD MUCH
CONFIDENCE TO THE RAIN FORECAST ACROSS THE SOUTH...SO WILL
GENERALLY STICK TO FORECAST CONTINUITY FOR NOW (WHICH KEEPS IT
IN). AS FOR LATE THIS AFTERNOON THE CUMULUS HAS BEEN THICKEST
ACROSS THE SOUTH WHILE IT HAS BEEN FADING OUT IN THE NORTH. LOOKS
LIKE THIS TREND WILL CONTINUE TONIGHT WHICH WILL RESULT IN WARMER
MIN TEMPS ACROSS THE SOUTH. THERE HAS BEEN FOG THE LAST COUPLE OF
NIGHTS...BUT ARE EXPECTING INCREASING CLOUDS ACROSS THE SOUTH. IF
ANY FOG FORMS TONIGHT IT MAY BE ACROSS THE NORTH. NOT SURE EXACTLY
WHEN ANY LIGHT SHOWERS WILL BREAK OUT ACROSS THE SOUTH AS EVEN THE
HIGH RESOLUTION MODELS DIFFER...SO WILL STICK WITH ITS ARRIVAL
COMING AFTER MIDNIGHT AND MAINLY ALONG AND SOUTH OF INTERSTATE 94.
12Z GFS IS THE MOST ROBUST AND FURTHEST NORTH WITH THE PCPN WHILE
OTHER MODELS ARE MUCH WEAKER...SO WILL GIVE THE LEAST WEIGHT TO
ITS SOLUTION. HOWEVER WILL EXPAND PCPN CHANCES A LITTLE FURTHER
NORTH FOR THURSDAY. WITH MORE CLOUDS/PCPN ACROSS THE SOUTH...HIGH
TEMPS WILL BE A LITTLE COOLER THERE. NEXT FRONTAL BOUNDARY WILL
ARRIVE LATE THU NIGHT IN THE NORTH BRINGING THE NEXT CHANCE FOR
PCPN.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 305 PM CDT WED AUG 27 2014
THE ABOVE MENTIONED FRONT WILL CONTINUE TO SLIDE SOUTH AND EAST ON
FRIDAY WITH PCPN CHANCES ALONG IT. HIGH PRESSURE SLIDES INTO THE
REGION LATER FRIDAY INTO SATURDAY ENDING ANY LINGERING PCPN
CHANCES.
FOR SAT NIGHT THROUGH WED...THE PERIOD SHOULD START OUT QUIET
ACTIVE...WITH MODELS IN GOOD AGREEMENT. A STRONG UPPER WAVE AND
FRONTAL BOUNDARY WILL MOVE THROUGH LATER SAT NIGHT THROUGH SUNDAY.
PWATS WILL RISE OVER 1.5 INCHES...WITH MLCAPES RISING OVER 1500 J/KG
IN THE EAST SUNDAY. WE EXPECT A ROUND OF SHOWERS AND STORMS WITH
ELEVATED CONVECTION SAT NIGHT INTO EARLY SUNDAY. MORE VIGOROUS SFC
BASED STORMS AND POSSIBLE STRONG/SEVERE STORMS ARE POSSIBLE
SUNDAY...DEPENDING ON TIMING OF WAVE AND FRONT. IT SHOULD BE MAINLY
DRY BY MONDAY THROUGH WED...WITH TEMPS NEAR NORMAL FOR EARLY
SEPTEMBER.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1140 PM CDT WED AUG 27 2014
LITTLE CHANGE WITH THE 06Z TAFS. OF CONCERN IS AN AREA OF MVFR
CIGS IN THE BISMARCK AREA THAT THE HRRR WANTS TO BRING A BIT NORTH
TOWARD DEVILS LAKE BY 11Z. DID ADD A TEMPO GROUP FOR MVFR CIGS AT
DVL FOR THIS DURING THE MORNING. OTHERWISE EXPECT THE 5-6K FT CIGS
TO SPREAD NORTHEAST GRADUALLY OVERNIGHT AND HANG AROUND MOST AREAS
THRU THURSDAY. DID NOT INCLUDE SHOWERS AT FARGO AS COVERAGE AND
TIMING VERY QUESTIONABLE AS BEST CHANCE REMAINS SOUTH OF FARGO.
WINDS MAINLY SOUTHERLY 8 TO 15 KTS.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...RIDDLE
SHORT TERM...GODON
LONG TERM...GODON/DK
AVIATION...RIDDLE
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
951 PM EDT FRI AUG 29 2014
.SYNOPSIS...
A WEAK NEARLY STATIONARY FRONT WILL LINGER OVER NORTH CAROLINA
TONIGHT AND THEN DISSIPATE BY SATURDAY NIGHT. A BERMUDA HIGH WILL
SET UP FOR THE WEEKEND AND EARLY NEXT WEEK...BRINGING TYPICAL
SUMMERTIME HEAT AND HUMIDITY...WITH SCATTERED AFTERNOON SHOWERS AND
THUNDERSTORMS EACH DAY.
&&
.NEAR TERM /THROUGH SATURDAY/...
EVENING UPDATE...MADE SOME MINOR TWEAKS TO THE MIN TEMP GRID AND ADJ
HR/LY TD/S TO FIT CURRENT TRENDS. A SFC BNDRY REMAINS ACROSS THE SRN
ZONES AND THE OP MODELS SHOW WEAK ATL MOIST ADV OVERNIGHT AS BL
WINDS VEER S/LY. THIS WILL KEEP THE SFC LAYER MOIST AND ALLOW FOR
FG/BR DEVELOPMENT ALONG WITH LOW STCU ACROSS THE ERN ZONES BEFORE
DAYBREAK. THE FG WILL LIKELY BECOME MOST DENSE ACROSS THE MTN
VALLEYS...BUT A WIDESPREAD EVENT IS NOT PROBABLE.
730 PM EDT UPDATE...CURRENT LAPS ANALYSIS SHOWS A MOIST SFC BNDRY
ACROSS THE SRN ZONES PROVIDING ENUF LIFT AND TD POOLING FOR ISOL
-SHRA TO DEVELOP. THESE CELLS WILL BE SHORT LIVED AND WILL LIKELY
NOT BECOME DEEP ENUF FOR A LIGHTNING CONCERN. TEMPS AND TD/S ARE IN
GOOD SHAPE AND ONLY MINOR ADJS WERE MADE TO SKY COVER ACROSS THE NRN
ZONES.
430 PM EDT UPDATE...THE FCST IS ON TRACK AND NEEDS ONLY MINOR
TWEAKS. MID LEVEL WARMING IS KEEPING CU FIELD IN CHECK WITH SOME
ENHANCEMENT SEEN ACROSS THE MTNS IN MECH LIFT. ISOLATED SHOWERS
WILL LIKELY FORM ACROSS THE RIDGETOPS OVER THE NEXT FEW HRS...BUT
MOST LOCALES WILL REMAIN DRY THROUGH THE AFTERNOON.
AS OF 130 PM EDT...LOW STRATUS ARE FINALLY DISSOLVING OVER OUR
PORTION OF THE NW NC PIEDMONT THOUGH OVC SKIES REMAIN JUST NE OF
CHARLOTTE. THESE CLOUDS ARE EXPECTED TO CONTINUE TO BREAK UP THROUGH
MID AFTERNOON. THE NEARLY STATIONARY BOUNDARY ON THE SRN FRINGE OF A
WEDGELIKE SFC RIDGE WHICH CAUSED THESE CLOUDS TO FORM EARLY THIS
MRNG REMAINS NEAR THE NC/SC BORDER. DEWPOINTS ARE CURRENTLY HIGHEST
IN AN ARC FROM ASHEVILLE TO SPARTANBURG TO CHARLOTTE...A RESULT OF
MOISTURE POOLING ALONG THE BOUNDARY. THIS HAS IMPLICATIONS FOR THE
FORECAST TONIGHT. HOWEVER...THOUGH ANALYZED CAPE VALUES ARE NOTABLY
HIGHER WITHIN THE AREA OF HIGHER DEWPOINTS...LOW TO MID LEVEL LAPSE
RATES ARE NOT GOOD ENOUGH EAST OF THE MTNS TO EXPECT DEEP
CONVECTION. HAVE MAINTAINED ISOLD TSRA MENTION OVER THE MTNS AND SRN
ESCARPMENT AREAS...BUT THAT/S IT.
TONIGHT THE UPPER RIDGE CONTINUES TO SHIFT EWD INTO CLASSIC BERMUDA
HIGH POSITION AS TROUGH MOVES INTO THE MISSISSIPPI VALLEY. ANY
REMNANT OF THE STATIONARY BOUNDARY APPEARS TO WASH OUT...AT LEAST
ENOUGH SO THAT ANY UPGLIDE WILL DIMINISH...SO LOW CLOUDS NOT
EXPECTED OVER THE BOUNDARY TONIGHT. VERY WEAK SOUTHERLY LLVL FLOW
WILL PREVAIL AGAIN OVER THE AREA WHICH DOES PROMPT THOUGHTS OF LOW
STRATUS OR FOG CREEPING UP FROM THE COAST...BUT MOISTURE DOES NOT
LOOK ESPECIALLY GOOD THIS FAR INLAND. A BETTER CASE CAN BE MADE FOR
FOG TO FORM WHERE SFC MOISTURE IS POOLING ALONG THE FRONT THIS
AFTN...GIVEN GOOD GUIDANCE SUPPORT FOR TEMPS COOLING BELOW THE
EXPECTED CROSSOVER TEMPS AS WELL AS WITH THE WEAK SOUTHERLY FLOW.
WILL ADVISE EVENING SHIFT TO CONSIDER THREAT OF PATCHY DENSE FOG
OVERNIGHT.
THAT UPPER TROUGH DOES BRING SOME WEAK DISTURBANCES NWD INTO THE
TENN VALLEY TOMORROW AFTN BUT THESE WILL HAVE MINIMAL IMPACT ON
FORCING OVER OUR AREA. LAPSE RATES AND MODEL CAPE VALUES ARE BEST
OVER THE SRN MTNS AND ADJACENT BLUE RIDGE...WHERE THE UPPER HEIGHTS
ARE A LITTLE LOWER. SOUTHERLY FLOW INTO THESE AREAS MAY ALSO ENHANCE
THE COVERAGE...SO I WILL MAINTAIN THE HIGHEST POPS THERE. FURTHER
EAST SUBSIDENCE CAPPING WILL KEEP THE FCST DRY. MAINLY DIURNAL
CUMULUS WILL BE SEEN FOR SKY COVER WITH MAX TEMPS NEAR NORMAL.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 200 PM FRIDAY...A WEAKENING SHORT WAVE TROUGH EJECTING FROM
THE GREAT PLAINS WILL ACT TO NUDGE THE SOUTHEAST CONUS UPPER HIGH
OFF THE SOUTHEAST COAST EARLY IN THE SHORT TERM...WHILE GENERALLY
RESULTING IN AN OVERALL LOWER AMPLITUDE UPPER PATTERN. A BERMUDA
HIGH WILL BECOME ESTABLISHED WITHIN THIS REGIME...WHICH WILL ACT TO
INCREASE MOISTURE AND INSTABILITY ACROSS THE WESTERN CAROLINAS AND
NORTH GEORGIA. ADDITIONALLY...A PLUME OF DEEP MOISTURE ACCOMPANYING
THE SHORT WAVE TROUGH/WEAKENING FRONTAL ZONE WILL APPROACH THE
FORECAST AREA BY SUNDAY MORNING. THIS SHOULD RESULT IN INCREASING
CHANCES FOR DEEP CONVECTION BEGINNING ACROSS THE WEST SUNDAY
NIGHT...WITH CHANCES INCREASING AND OVERSPREADING THE REMAINDER OF
THE AREA BY SUNDAY AFTERNOON. TERRAIN EFFECTS AND LEE TROUGH
INTERACTING WITH LINGERING MOISTURE PLUME...ALONG WITH RESPECTABLE
SBCAPE VALUES (GENERALLY 1500 TO 2500 J/KG PER FORECAST SOUNDINGS)
SHOULD SUPPORT SCATTERED TO PERHAPS NUMEROUS CONVECTION...WITH THE
HIGHEST POPS OCCURRING NEAR THE NC BLUE RIDGE. SHEAR WILL REMAIN
QUITE WEAK THROUGHOUT THE PERIOD...SO SEVERE STORM CHANCES WILL BE
LIMITED TO THE ISOLATED PULSE VARIETY.
WITH FRONTAL ZONE EXPECTED TO WEAKEN ACROSS THE EASTERN CONUS...
EXPECT A MORE TYPICAL DIURNAL WIDELY SCATTERED CONVECTIVE TREND TO
RETURN BY THE END OF THE PERIOD. THE BREAKDOWN OF THE RIDGE AND
INCREASING CLOUD COVER/CONVECTION SHOULD SPELL A PERIOD OF SLIGHTLY
BELOW NORMAL MAX TEMPS/NEAR NORMAL MINS THROUGH THE PERIOD.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 150 PM FRIDAY...THE MEDIUM RANGE PERIOD BEGINS 00Z TUESDAY
WITH A NEARLY ZONAL PATTERN ACROSS THE NATION AS AN UPPER RIDGE
DEPARTS EAST FROM THE ATLANTIC COAST. A SUBTROPICAL RIDGE BEING
SUPPRESSED SOUTH OVER FLORIDA AT 00Z TUES WILL RETROGRADE OVER THE
DEEP SOUTH BEING CENTERED OVER THE GULF STATES IN MID WEEK. THIS
RIDGE WILL EXPAND INTO LATE WEEK CREATING A GREATER AMPLITUDE
PATTERN THURS AND FRI WITH THE JET STREAM FROM CALIFORNIA TO THE
DAKOTAS TO NEW ENGLAND. THERE APPEARS TO BE A TREND IN THE
MODELS...ESPECIALLY IN THE GFS...OF MOVING THE CENTER OF THE RIDGE
EVEN FARTHER WEST AT THE END OF NEXT WEEK. IF THE CENTER OF THE
RIDGE SETS UP AROUND OKLAHOMA NEXT WEEKEND...OUR PATTERN MAY SHIFT
FROM BEING IN A RIDGE TO BEING IN NW FLOW WHICH WOULD BRING MCS
SYSTEMS FROM OVER THE TOP OF THE RIDGE TO THE CAROLINAS.
A WEAK COLD FRONT WILL DROP DOWN FROM THE NORTH IN MID WEEK BUT IT
IS QUESTIONABLE WHETHER THE FRONT WILL REACH OUR AREA BEFORE
DISSIPATING. THIS BOUNDARY WILL PROVIDE A FOCUS FOR CONVECTION IN
MID WEEK ESPECIALLY IN THE PM HOURS. LOW LEVEL WIND WILL BE LIGHT
AND VARY FROM DAY TO DAY DEPENDING ON THE INFLUENCES OF PASSING
SHORTWAVES TO THE NORTH...A PERSISTENT LEE TROUGH AND
WHETHER THE FRONT MAKES IT THROUGH OR NOT.
TEMPERATURES ARE FORECAST TO BE ABOVE NORMAL THROUGH THE PERIOD
UNDER THE UPPER RIDGE. MAXES ABOVE BY 5 TO 7 DEGREES IN MID WEEK AND
3 TO 5 ABOVE ON FRIDAY.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
AT CLT...VFR CONDS THROUGH MOST OF THE OVERNIGHT WITH LIKELY MVFR
VSBY SETTING UP AFT 10Z THROUGH 13Z. BNDRY LAYER WINDS WILL MAINTAIN
A MOIST ATL FLOW AS WINDS VEER OVERNIGHT AND THIS COULD ALSO SUPPORT
LOW STCU. THE RAP SOUNDINGS INDICATE MORE OF CIG THREAT THAN
FG/BR...HOWEVER THE STAT GUIDANCE GIVES MORE WEIGHT TO MVFR VSBY AND
NONE TO CIGS. THE CURRENT P/GRAD RIDGE BECOMES MERIDIONALLY ALIGNED
SAT...WHICH WILL SUPPORT SSE/LY FLOW THRU THE AFTERNOON.
ELSEWHERE...THE SC SITES WILL REMAIN VFR OVERNIGHT AS SOUNDINGS
INDICATE DRY LLVLS AND TDDS ABOVE 2 C...HOWEVER A BNDRY SOUTH MAY
SUPPORT MFVR VSBY AFT 10Z AT KAND. THERE COULD BE SOME MVFR LEVEL
STCU DEVELOPING AFT 09Z OR SO...BUT THE OVERALL AVAIL MOISTURE
SHOULD BE TOO LOW FOR CIGS. AT KAVL...VSBYS SHOULD START DROPPING
AFT 05Z AND BECOME IFR BTW 09Z/12Z AS DRYING ALOFT DEVELOPS OVER A
SHALLOW MOIST LAYER. VISIBILITIES AT KHKY WILL ALSO DROP
OVERNIGHT...BUT PROBABLY REMAIN IN THE MVFR RANGE WITH A RELATIVELY
DRYER SFC LAYER THAN THE MTN VALLEYS.
OUTLOOK...MOISTURE RETURN BEGINNING SAT NIGHT WILL LEAD TO
INCREASING CHANCES FOR ISOLATED/SCATTERED DIURNAL SHRA AND TSRA WITH
THE GREATEST PROBABILITIES RESIDING ALONG THE HIGH TERRAIN. IN
ADDITION...MORNING FOG/STRATUS WILL BE POSSIBLE WITH THE MOUNTAINS
ONCE AGAIN HAVING THE GREATEST CHANCES AT RESTRICTIONS.
CONFIDENCE TABLE...
02-08Z 08-14Z 14-20Z 20-02Z
KCLT HIGH 100% HIGH 97% HIGH 100% HIGH 100%
KGSP HIGH 100% HIGH 97% HIGH 100% HIGH 100%
KAVL HIGH 100% HIGH 95% HIGH 100% HIGH 100%
KHKY HIGH 97% HIGH 96% HIGH 100% HIGH 100%
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...SBK/WIMBERLEY
SHORT TERM...JDL
LONG TERM...DEO
AVIATION...SBK
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
742 PM EDT FRI AUG 29 2014
.SYNOPSIS...
A WEAK NEARLY STATIONARY FRONT WILL LINGER OVER NORTH CAROLINA
TONIGHT AND THEN DISSIPATE BY SATURDAY NIGHT. A BERMUDA HIGH WILL
SET UP FOR THE WEEKEND AND EARLY NEXT WEEK...BRINGING TYPICAL
SUMMERTIME HEAT AND HUMIDITY...WITH SCATTERED AFTERNOON SHOWERS AND
THUNDERSTORMS EACH DAY.
&&
.NEAR TERM /THROUGH SATURDAY/...
730 PM EDT UPDATE...CURRENT LAPS ANALYSIS SHOWS A MOIST SFC BNDRY
ACROSS THE SRN ZONES PROVIDING ENUF LIFT AND TD POOLING FOR ISOL
-SHRA TO DEVELOP. THESE CELLS WILL BE SHORT LIVED AND WILL LIKELY
NOT BECOME DEEP ENUF FOR A LIGHTNING CONCERN. TEMPS AND TD/S ARE IN
GOOD SHAPE AND ONLY MINOR ADJS WERE MADE TO SKY COVER ACROSS THE NRN
ZONES.
430 PM EDT UPDATE...THE FCST IS ON TRACK AND NEEDS ONLY MINOR
TWEAKS. MID LEVEL WARMING IS KEEPING CU FIELD IN CHECK WITH SOME
ENHANCEMENT SEEN ACROSS THE MTNS IN MECH LIFT. ISOLATED SHOWERS
WILL LIKELY FORM ACROSS THE RIDGETOPS OVER THE NEXT FEW HRS...BUT
MOST LOCALES WILL REMAIN DRY THROUGH THE AFTERNOON.
AS OF 130 PM EDT...LOW STRATUS ARE FINALLY DISSOLVING OVER OUR
PORTION OF THE NW NC PIEDMONT THOUGH OVC SKIES REMAIN JUST NE OF
CHARLOTTE. THESE CLOUDS ARE EXPECTED TO CONTINUE TO BREAK UP THROUGH
MID AFTERNOON. THE NEARLY STATIONARY BOUNDARY ON THE SRN FRINGE OF A
WEDGELIKE SFC RIDGE WHICH CAUSED THESE CLOUDS TO FORM EARLY THIS
MRNG REMAINS NEAR THE NC/SC BORDER. DEWPOINTS ARE CURRENTLY HIGHEST
IN AN ARC FROM ASHEVILLE TO SPARTANBURG TO CHARLOTTE...A RESULT OF
MOISTURE POOLING ALONG THE BOUNDARY. THIS HAS IMPLICATIONS FOR THE
FORECAST TONIGHT. HOWEVER...THOUGH ANALYZED CAPE VALUES ARE NOTABLY
HIGHER WITHIN THE AREA OF HIGHER DEWPOINTS...LOW TO MID LEVEL LAPSE
RATES ARE NOT GOOD ENOUGH EAST OF THE MTNS TO EXPECT DEEP
CONVECTION. HAVE MAINTAINED ISOLD TSRA MENTION OVER THE MTNS AND SRN
ESCARPMENT AREAS...BUT THAT/S IT.
TONIGHT THE UPPER RIDGE CONTINUES TO SHIFT EWD INTO CLASSIC BERMUDA
HIGH POSITION AS TROUGH MOVES INTO THE MISSISSIPPI VALLEY. ANY
REMNANT OF THE STATIONARY BOUNDARY APPEARS TO WASH OUT...AT LEAST
ENOUGH SO THAT ANY UPGLIDE WILL DIMINISH...SO LOW CLOUDS NOT
EXPECTED OVER THE BOUNDARY TONIGHT. VERY WEAK SOUTHERLY LLVL FLOW
WILL PREVAIL AGAIN OVER THE AREA WHICH DOES PROMPT THOUGHTS OF LOW
STRATUS OR FOG CREEPING UP FROM THE COAST...BUT MOISTURE DOES NOT
LOOK ESPECIALLY GOOD THIS FAR INLAND. A BETTER CASE CAN BE MADE FOR
FOG TO FORM WHERE SFC MOISTURE IS POOLING ALONG THE FRONT THIS
AFTN...GIVEN GOOD GUIDANCE SUPPORT FOR TEMPS COOLING BELOW THE
EXPECTED CROSSOVER TEMPS AS WELL AS WITH THE WEAK SOUTHERLY FLOW.
WILL ADVISE EVENING SHIFT TO CONSIDER THREAT OF PATCHY DENSE FOG
OVERNIGHT.
THAT UPPER TROUGH DOES BRING SOME WEAK DISTURBANCES NWD INTO THE
TENN VALLEY TOMORROW AFTN BUT THESE WILL HAVE MINIMAL IMPACT ON
FORCING OVER OUR AREA. LAPSE RATES AND MODEL CAPE VALUES ARE BEST
OVER THE SRN MTNS AND ADJACENT BLUE RIDGE...WHERE THE UPPER HEIGHTS
ARE A LITTLE LOWER. SOUTHERLY FLOW INTO THESE AREAS MAY ALSO ENHANCE
THE COVERAGE...SO I WILL MAINTAIN THE HIGHEST POPS THERE. FURTHER
EAST SUBSIDENCE CAPPING WILL KEEP THE FCST DRY. MAINLY DIURNAL
CUMULUS WILL BE SEEN FOR SKY COVER WITH MAX TEMPS NEAR NORMAL.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 200 PM FRIDAY...A WEAKENING SHORT WAVE TROUGH EJECTING FROM
THE GREAT PLAINS WILL ACT TO NUDGE THE SOUTHEAST CONUS UPPER HIGH
OFF THE SOUTHEAST COAST EARLY IN THE SHORT TERM...WHILE GENERALLY
RESULTING IN AN OVERALL LOWER AMPLITUDE UPPER PATTERN. A BERMUDA
HIGH WILL BECOME ESTABLISHED WITHIN THIS REGIME...WHICH WILL ACT TO
INCREASE MOISTURE AND INSTABILITY ACROSS THE WESTERN CAROLINAS AND
NORTH GEORGIA. ADDITIONALLY...A PLUME OF DEEP MOISTURE ACCOMPANYING
THE SHORT WAVE TROUGH/WEAKENING FRONTAL ZONE WILL APPROACH THE
FORECAST AREA BY SUNDAY MORNING. THIS SHOULD RESULT IN INCREASING
CHANCES FOR DEEP CONVECTION BEGINNING ACROSS THE WEST SUNDAY
NIGHT...WITH CHANCES INCREASING AND OVERSPREADING THE REMAINDER OF
THE AREA BY SUNDAY AFTERNOON. TERRAIN EFFECTS AND LEE TROUGH
INTERACTING WITH LINGERING MOISTURE PLUME...ALONG WITH RESPECTABLE
SBCAPE VALUES (GENERALLY 1500 TO 2500 J/KG PER FORECAST SOUNDINGS)
SHOULD SUPPORT SCATTERED TO PERHAPS NUMEROUS CONVECTION...WITH THE
HIGHEST POPS OCCURRING NEAR THE NC BLUE RIDGE. SHEAR WILL REMAIN
QUITE WEAK THROUGHOUT THE PERIOD...SO SEVERE STORM CHANCES WILL BE
LIMITED TO THE ISOLATED PULSE VARIETY.
WITH FRONTAL ZONE EXPECTED TO WEAKEN ACROSS THE EASTERN CONUS...
EXPECT A MORE TYPICAL DIURNAL WIDELY SCATTERED CONVECTIVE TREND TO
RETURN BY THE END OF THE PERIOD. THE BREAKDOWN OF THE RIDGE AND
INCREASING CLOUD COVER/CONVECTION SHOULD SPELL A PERIOD OF SLIGHTLY
BELOW NORMAL MAX TEMPS/NEAR NORMAL MINS THROUGH THE PERIOD.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 150 PM FRIDAY...THE MEDIUM RANGE PERIOD BEGINS 00Z TUESDAY
WITH A NEARLY ZONAL PATTERN ACROSS THE NATION AS AN UPPER RIDGE
DEPARTS EAST FROM THE ATLANTIC COAST. A SUBTROPICAL RIDGE BEING
SUPPRESSED SOUTH OVER FLORIDA AT 00Z TUES WILL RETROGRADE OVER THE
DEEP SOUTH BEING CENTERED OVER THE GULF STATES IN MID WEEK. THIS
RIDGE WILL EXPAND INTO LATE WEEK CREATING A GREATER AMPLITUDE
PATTERN THURS AND FRI WITH THE JET STREAM FROM CALIFORNIA TO THE
DAKOTAS TO NEW ENGLAND. THERE APPEARS TO BE A TREND IN THE
MODELS...ESPECIALLY IN THE GFS...OF MOVING THE CENTER OF THE RIDGE
EVEN FARTHER WEST AT THE END OF NEXT WEEK. IF THE CENTER OF THE
RIDGE SETS UP AROUND OKLAHOMA NEXT WEEKEND...OUR PATTERN MAY SHIFT
FROM BEING IN A RIDGE TO BEING IN NW FLOW WHICH WOULD BRING MCS
SYSTEMS FROM OVER THE TOP OF THE RIDGE TO THE CAROLINAS.
A WEAK COLD FRONT WILL DROP DOWN FROM THE NORTH IN MID WEEK BUT IT
IS QUESTIONABLE WHETHER THE FRONT WILL REACH OUR AREA BEFORE
DISSIPATING. THIS BOUNDARY WILL PROVIDE A FOCUS FOR CONVECTION IN
MID WEEK ESPECIALLY IN THE PM HOURS. LOW LEVEL WIND WILL BE LIGHT
AND VARY FROM DAY TO DAY DEPENDING ON THE INFLUENCES OF PASSING
SHORTWAVES TO THE NORTH...A PERSISTENT LEE TROUGH AND
WHETHER THE FRONT MAKES IT THROUGH OR NOT.
TEMPERATURES ARE FORECAST TO BE ABOVE NORMAL THROUGH THE PERIOD
UNDER THE UPPER RIDGE. MAXES ABOVE BY 5 TO 7 DEGREES IN MID WEEK AND
3 TO 5 ABOVE ON FRIDAY.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AT CLT...VFR CONDS THROUGH MOST OF THE OVERNIGHT WITH LIKELY MVFR
VSBY SETTING UP AFT 10Z THROUGH 13Z. BNDRY LAYER WINDS WILL MAINTAIN
A MOIST ATL FLOW AS WINDS VEER OVERNIGHT AND THIS COULD ALSO SUPPORT
LOW STCU. THE RAP SOUNDINGS INDICATE MORE OF CIG THREAT THAN
FG/BR...HOWEVER THE STAT GUIDANCE GIVES MORE WEIGHT TO MVFR VSBY AND
NONE TO CIGS. THE CURRENT P/GRAD RIDGE BECOMES MERIDIONALLY ALIGNED
SAT...WHICH WILL SUPPORT SSE/LY FLOW THRU THE AFTERNOON.
ELSEWHERE...THE SC SITES WILL REMAIN VFR OVERNIGHT AS SOUNDINGS
INDICATE DRY LLVLS AND TDDS ABOVE 2 C...HOWEVER A BNDRY SOUTH MAY
SUPPORT MFVR VSBY AFT 10Z AT KAND. THERE COULD BE SOME MVFR LEVEL
STCU DEVELOPING AFT 09Z OR SO...BUT THE OVERALL AVAIL MOISTURE
SHOULD BE TOO LOW FOR CIGS. AT KAVL...VSBYS SHOULD START DROPPING
AFT 05Z AND BECOME IFR BTW 09Z/12Z AS DRYING ALOFT DEVELOPS OVER A
SHALLOW MOIST LAYER. VISIBILITIES AT KHKY WILL ALSO DROP
OVERNIGHT...BUT PROBABLY REMAIN IN THE MVFR RANGE WITH A RELATIVELY
DRYER SFC LAYER THAN THE MTN VALLEYS.
OUTLOOK...MOISTURE RETURN BEGINNING SAT NIGHT WILL LEAD TO
INCREASING CHANCES FOR ISOLATED/SCATTERED DIURNAL SHRA AND TSRA WITH
THE GREATEST PROBABILITIES RESIDING ALONG THE HIGH TERRAIN. IN
ADDITION...MORNING FOG/STRATUS WILL BE POSSIBLE WITH THE MOUNTAINS
ONCE AGAIN HAVING THE GREATEST CHANCES AT RESTRICTIONS.
CONFIDENCE TABLE...
23-05Z 05-11Z 11-17Z 17-23Z
KCLT HIGH 100% HIGH 100% HIGH 94% HIGH 100%
KGSP HIGH 100% HIGH 100% HIGH 97% HIGH 100%
KAVL HIGH 100% HIGH 100% HIGH 94% HIGH 100%
KHKY HIGH 100% HIGH 80% HIGH 97% HIGH 100%
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 100% HIGH 100% HIGH 88% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...SBK/WIMBERLEY
SHORT TERM...JDL
LONG TERM...DEO
AVIATION...SBK
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
739 PM EDT FRI AUG 29 2014
.SYNOPSIS...
A WEAK NEARLY STATIONARY FRONT WILL LINGER OVER NORTH CAROLINA
TONIGHT AND THEN DISSIPATE BY SATURDAY NIGHT. A BERMUDA HIGH WILL
SET UP FOR THE WEEKEND AND EARLY NEXT WEEK...BRINGING TYPICAL
SUMMERTIME HEAT AND HUMIDITY...WITH SCATTERED AFTERNOON SHOWERS AND
THUNDERSTORMS EACH DAY.
&&
.NEAR TERM /THROUGH SATURDAY/...
730 PM EDT UPDATE...CURRENT LAPS ANALYSIS SHOWS A MOIST SFC BNDRY
ACROSS THE SRN ZONES PROVIDING ENUF LIFT AND TD POOLING FOR ISOL
-SHRA TO DEVELOP. THESE CELLS WILL BE SHORT LIVED AND WILL LIKELY
NOT BECOME DEEP ENUF FOR A LIGHTNING CONCERN. TEMPS AND TD/S ARE IN
GOOD SHAPE AND ONLY MINOR ADJS WERE MADE TO SKY COVER ACROSS THE NRN
ZONES.
430 PM EDT UPDATE...THE FCST IS ON TRACK AND NEEDS ONLY MINOR
TWEAKS. MID LEVEL WARMING IS KEEPING CU FIELD IN CHECK WITH SOME
ENHANCEMENT SEEN ACROSS THE MTNS IN MECH LIFT. ISOLATED SHOWERS
WILL LIKELY FORM ACROSS THE RIDGETOPS OVER THE NEXT FEW HRS...BUT
MOST LOCALES WILL REMAIN DRY THROUGH THE AFTERNOON.
AS OF 130 PM EDT...LOW STRATUS ARE FINALLY DISSOLVING OVER OUR
PORTION OF THE NW NC PIEDMONT THOUGH OVC SKIES REMAIN JUST NE OF
CHARLOTTE. THESE CLOUDS ARE EXPECTED TO CONTINUE TO BREAK UP THROUGH
MID AFTERNOON. THE NEARLY STATIONARY BOUNDARY ON THE SRN FRINGE OF A
WEDGELIKE SFC RIDGE WHICH CAUSED THESE CLOUDS TO FORM EARLY THIS
MRNG REMAINS NEAR THE NC/SC BORDER. DEWPOINTS ARE CURRENTLY HIGHEST
IN AN ARC FROM ASHEVILLE TO SPARTANBURG TO CHARLOTTE...A RESULT OF
MOISTURE POOLING ALONG THE BOUNDARY. THIS HAS IMPLICATIONS FOR THE
FORECAST TONIGHT. HOWEVER...THOUGH ANALYZED CAPE VALUES ARE NOTABLY
HIGHER WITHIN THE AREA OF HIGHER DEWPOINTS...LOW TO MID LEVEL LAPSE
RATES ARE NOT GOOD ENOUGH EAST OF THE MTNS TO EXPECT DEEP
CONVECTION. HAVE MAINTAINED ISOLD TSRA MENTION OVER THE MTNS AND SRN
ESCARPMENT AREAS...BUT THAT/S IT.
TONIGHT THE UPPER RIDGE CONTINUES TO SHIFT EWD INTO CLASSIC BERMUDA
HIGH POSITION AS TROUGH MOVES INTO THE MISSISSIPPI VALLEY. ANY
REMNANT OF THE STATIONARY BOUNDARY APPEARS TO WASH OUT...AT LEAST
ENOUGH SO THAT ANY UPGLIDE WILL DIMINISH...SO LOW CLOUDS NOT
EXPECTED OVER THE BOUNDARY TONIGHT. VERY WEAK SOUTHERLY LLVL FLOW
WILL PREVAIL AGAIN OVER THE AREA WHICH DOES PROMPT THOUGHTS OF LOW
STRATUS OR FOG CREEPING UP FROM THE COAST...BUT MOISTURE DOES NOT
LOOK ESPECIALLY GOOD THIS FAR INLAND. A BETTER CASE CAN BE MADE FOR
FOG TO FORM WHERE SFC MOISTURE IS POOLING ALONG THE FRONT THIS
AFTN...GIVEN GOOD GUIDANCE SUPPORT FOR TEMPS COOLING BELOW THE
EXPECTED CROSSOVER TEMPS AS WELL AS WITH THE WEAK SOUTHERLY FLOW.
WILL ADVISE EVENING SHIFT TO CONSIDER THREAT OF PATCHY DENSE FOG
OVERNIGHT.
THAT UPPER TROUGH DOES BRING SOME WEAK DISTURBANCES NWD INTO THE
TENN VALLEY TOMORROW AFTN BUT THESE WILL HAVE MINIMAL IMPACT ON
FORCING OVER OUR AREA. LAPSE RATES AND MODEL CAPE VALUES ARE BEST
OVER THE SRN MTNS AND ADJACENT BLUE RIDGE...WHERE THE UPPER HEIGHTS
ARE A LITTLE LOWER. SOUTHERLY FLOW INTO THESE AREAS MAY ALSO ENHANCE
THE COVERAGE...SO I WILL MAINTAIN THE HIGHEST POPS THERE. FURTHER
EAST SUBSIDENCE CAPPING WILL KEEP THE FCST DRY. MAINLY DIURNAL
CUMULUS WILL BE SEEN FOR SKY COVER WITH MAX TEMPS NEAR NORMAL.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 200 PM FRIDAY...A WEAKENING SHORT WAVE TROUGH EJECTING FROM
THE GREAT PLAINS WILL ACT TO NUDGE THE SOUTHEAST CONUS UPPER HIGH
OFF THE SOUTHEAST COAST EARLY IN THE SHORT TERM...WHILE GENERALLY
RESULTING IN AN OVERALL LOWER AMPLITUDE UPPER PATTERN. A BERMUDA
HIGH WILL BECOME ESTABLISHED WITHIN THIS REGIME...WHICH WILL ACT TO
INCREASE MOISTURE AND INSTABILITY ACROSS THE WESTERN CAROLINAS AND
NORTH GEORGIA. ADDITIONALLY...A PLUME OF DEEP MOISTURE ACCOMPANYING
THE SHORT WAVE TROUGH/WEAKENING FRONTAL ZONE WILL APPROACH THE
FORECAST AREA BY SUNDAY MORNING. THIS SHOULD RESULT IN INCREASING
CHANCES FOR DEEP CONVECTION BEGINNING ACROSS THE WEST SUNDAY
NIGHT...WITH CHANCES INCREASING AND OVERSPREADING THE REMAINDER OF
THE AREA BY SUNDAY AFTERNOON. TERRAIN EFFECTS AND LEE TROUGH
INTERACTING WITH LINGERING MOISTURE PLUME...ALONG WITH RESPECTABLE
SBCAPE VALUES (GENERALLY 1500 TO 2500 J/KG PER FORECAST SOUNDINGS)
SHOULD SUPPORT SCATTERED TO PERHAPS NUMEROUS CONVECTION...WITH THE
HIGHEST POPS OCCURRING NEAR THE NC BLUE RIDGE. SHEAR WILL REMAIN
QUITE WEAK THROUGHOUT THE PERIOD...SO SEVERE STORM CHANCES WILL BE
LIMITED TO THE ISOLATED PULSE VARIETY.
WITH FRONTAL ZONE EXPECTED TO WEAKEN ACROSS THE EASTERN CONUS...
EXPECT A MORE TYPICAL DIURNAL WIDELY SCATTERED CONVECTIVE TREND TO
RETURN BY THE END OF THE PERIOD. THE BREAKDOWN OF THE RIDGE AND
INCREASING CLOUD COVER/CONVECTION SHOULD SPELL A PERIOD OF SLIGHTLY
BELOW NORMAL MAX TEMPS/NEAR NORMAL MINS THROUGH THE PERIOD.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 150 PM FRIDAY...THE MEDIUM RANGE PERIOD BEGINS 00Z TUESDAY
WITH A NEARLY ZONAL PATTERN ACROSS THE NATION AS AN UPPER RIDGE
DEPARTS EAST FROM THE ATLANTIC COAST. A SUBTROPICAL RIDGE BEING
SUPPRESSED SOUTH OVER FLORIDA AT 00Z TUES WILL RETROGRADE OVER THE
DEEP SOUTH BEING CENTERED OVER THE GULF STATES IN MID WEEK. THIS
RIDGE WILL EXPAND INTO LATE WEEK CREATING A GREATER AMPLITUDE
PATTERN THURS AND FRI WITH THE JET STREAM FROM CALIFORNIA TO THE
DAKOTAS TO NEW ENGLAND. THERE APPEARS TO BE A TREND IN THE
MODELS...ESPECIALLY IN THE GFS...OF MOVING THE CENTER OF THE RIDGE
EVEN FARTHER WEST AT THE END OF NEXT WEEK. IF THE CENTER OF THE
RIDGE SETS UP AROUND OKLAHOMA NEXT WEEKEND...OUR PATTERN MAY SHIFT
FROM BEING IN A RIDGE TO BEING IN NW FLOW WHICH WOULD BRING MCS
SYSTEMS FROM OVER THE TOP OF THE RIDGE TO THE CAROLINAS.
A WEAK COLD FRONT WILL DROP DOWN FROM THE NORTH IN MID WEEK BUT IT
IS QUESTIONABLE WHETHER THE FRONT WILL REACH OUR AREA BEFORE
DISSIPATING. THIS BOUNDARY WILL PROVIDE A FOCUS FOR CONVECTION IN
MID WEEK ESPECIALLY IN THE PM HOURS. LOW LEVEL WIND WILL BE LIGHT
AND VARY FROM DAY TO DAY DEPENDING ON THE INFLUENCES OF PASSING
SHORTWAVES TO THE NORTH...A PERSISTENT LEE TROUGH AND
WHETHER THE FRONT MAKES IT THROUGH OR NOT.
TEMPERATURES ARE FORECAST TO BE ABOVE NORMAL THROUGH THE PERIOD
UNDER THE UPPER RIDGE. MAXES ABOVE BY 5 TO 7 DEGREES IN MID WEEK AND
3 TO 5 ABOVE ON FRIDAY.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AT CLT...VFR CONDS THROUGH MOST OF THE OVERNIGHT WITH LIKELY MVFR
VSBY SETTING UP AFT 10Z THROUGH 13Z. BNDRY LAYER WINDS WILL MAINTAIN
A MOIST ATL FLOW AS WINDS VEER OVERNIGHT AND THIS COULD ALSO SUPPORT
LOW STCU. THE RAP SOUNDINGS INDICATE MORE OF A FG/BR THREAT THAN
CIGS AS DOES THE STAT GUIDANCE...SO WILL GIVE MORE WEIGHT TO THE
MVFR VSBY. THE CURRENT P/GRAD RIDGE BECOMES MERIDIONALLY ALIGNED
SAT...WHICH WILL SUPPORT SSE/LY FLOW THRU THE AFTERNOON.
ELSEWHERE...THE SC SITES WILL REMAIN VFR OVERNIGHT AS SOUNDINGS
INDICATE DRY LLVLS AND TDDS ABOVE 2 C...HOWEVER A BNDRY SOUTH MAY
SUPPORT MFVR VSBY AFT 10Z AT KAND. THERE COULD BE SOME MVFR LEVEL
STCU DEVELOPING AFT 09Z OR SO...BUT THE OVERALL AVAIL MOISTURE
SHOULD BE TOO LOW FOR CIGS. AT KAVL...VSBYS SHOULD START DROPPING
AFT 05Z AND BECOME IFR BTW 09Z/12Z AS DRYING ALOFT DEVELOPS OVER A
SHALLOW MOIST LAYER. VISIBILITIES AT KHKY WILL ALSO DROP
OVERNIGHT...BUT PROBABLY REMAIN IN THE MVFR RANGE WITH A RELATIVELY
DRYER SFC LAYER THAN THE MTN VALLEYS.
OUTLOOK...MOISTURE RETURN BEGINNING SAT NIGHT WILL LEAD TO
INCREASING CHANCES FOR ISOLATED/SCATTERED DIURNAL SHRA AND TSRA WITH
THE GREATEST PROBABILITIES RESIDING ALONG THE HIGH TERRAIN. IN
ADDITION...MORNING FOG/STRATUS WILL BE POSSIBLE WITH THE MOUNTAINS
ONCE AGAIN HAVING THE GREATEST CHANCES AT RESTRICTIONS.
CONFIDENCE TABLE...
23-05Z 05-11Z 11-17Z 17-23Z
KCLT HIGH 100% HIGH 100% HIGH 94% HIGH 100%
KGSP HIGH 100% HIGH 100% HIGH 97% HIGH 100%
KAVL HIGH 100% HIGH 100% HIGH 94% HIGH 100%
KHKY HIGH 100% HIGH 80% HIGH 97% HIGH 100%
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 100% HIGH 100% HIGH 88% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...SBK/WIMBERLEY
SHORT TERM...JDL
LONG TERM...DEO
AVIATION...SBK
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
511 PM CDT THU AUG 28 2014
.UPDATE...ADDED AVIATION SECTION FOR 00Z TAF`S.
&&
.AVIATION...BNA/CKV/CSV...ISOLATED CELLS CONTINUE ACROSS MAINLY
NORTHERN MIDDLE TENNESSEE LATE THIS AFTERNOON. HRRR SHOWS
EXISTING ACTIVITY DISSIPATING DURING THE EVENING AS WE LOSE
DAYTIME HEATING. SURFACE RIDGE HAS SLIPPED TO OUR EAST WITH WEAK
RETURN FLOW NOW UNDERWAY. EXPECT FULL RADIATIONAL COOLING
OVERNIGHT, WITH LIGHT FOG POSSIBLE AT CKV AND CSV. VERY LITTLE
CHANCE OF CONVECTION ON FRIDAY, SO WE SHOULD BE VFR THE NEXT 24
HRS OUTSIDE OF EARLY MORNING FOG.
&&
.PREV DISCUSSION... /ISSUED 315 PM CDT THU AUG 28 2014/
DISCUSSION...
LATEST RADAR IMAGERY SHOWS ISOLATED SMALL SHOWERS AND A FEW
THUNDERSTORMS HAVE DEVELOPED ALONG AND NORTH OF THE I-40 CORRIDOR.
ACTIVITY HAS BEEN GENERALLY STATIONARY OR OOZING SOUTHWARD...AND
COULD SEE SOME LOCALLY HEAVY RAINFALL AND BRIEF GUSTY WINDS AT
TIMES ALTHOUGH NOTHING STRONG OR SEVERE IS ANTICIPATED. CONVECTION
SHOULD DISSIPATE QUICKLY THIS EVENING WITH LOSS OF DAYTIME HEATING
BUT LEFT IN A SLIGHT CHANCE POP FOR NORTHERN ZONES.
DRIER AIRMASS NOTED TO OUR SOUTHEAST WITH DEWPOINTS IN THE 50S
AND PWATS WELL BELOW 1 INCH WILL ADVECT NORTHWEST INTO THE MID
STATE ON FRIDAY...KEEPING PRECIP CHANCES NIL BUT ALLOWING
AFTERNOON TEMPS TO WARM INTO THE LOW TO MID 90S. THIS DRY PERIOD
WILL BE VERY SHORT LIVED AS A SLUG OF DEEP TROPICAL MOISTURE WITH
PWATS ABOVE 2 INCHES MOVES OUT OF THE GULF AND INTO THE FORECAST
AREA ON SATURDAY AND REMAINS OVER THE AREA THROUGH SUNDAY.
SCATTERED TO NUMEROUS SHOWERS AND STORMS ARE ANTICIPATED BOTH DAYS
WITH LIKELY POPS WARRANTED...WITH MORE COVERAGE OF PRECIP LIKELY
SATURDAY NIGHT INTO SUNDAY WHEN PWATS PEAK AROUND 2.1 INCHES PER
12Z GFS. CLOUDS AND PRECIP WILL KEEP TEMPS DOWN ACCORDINGLY...BUT
DIFFICULT TO KNOW JUST HOW MUCH THIS FAR OUT IN TIME SO HAVE KEPT
HIGHS GENERALLY IN THE 80S TO AROUND 90 OVER THE WEEKEND.
PRECIP CHANCES RETURN TO MORE TYPICAL LOW LEVELS FROM MONDAY
THROUGH THE REST OF THE WEEK AS AN UPPER LEVEL RIDGE REBUILDS
ALONG THE GULF COAST AND EDGES NORTHWARD INTO OUR REGION. H5 RIDGE
DOES NOT LOOK OVERLY POTENT AT AROUND 590 DM...SO HIGHS IN THE LOW
90S WITH LOWS AROUND 70 LOOK REASONABLE FOR NEXT WEEK ALONG WITH
SOME ISOLATED TO WIDELY SCATTERED SHOWERS AND STORMS EACH DAY.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
ROSE
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
340 PM CDT THU AUG 28 2014
.SHORT TERM...
(Tonight and Friday)
Rain chances for the next 24 hours continue to look more promising.
The latest WSR-88D data indicate showers and thunderstorms are
developing across the Big Country. The RUC indicates this activity
will continue to develop and spread into mainly our northwestern
counties during the next 6 hours. Overnight tonight, the NAM
fragments the QPF into small areas across mainly our northwestern
counties. Given the uncertainty across our southeastern counties,
slight chance PoPs still look good there. Elsewhere, and especially
north of our Interstate 20 corridor, chance PoPs look best. As the
upper trough axis pushes farther east tomorrow, the better rain
chances will expand south and include more of our southern counties.
The main thunderstorm threats for the next 24 hours are deadly
lightning and flash flooding from locally heavy rainfall.
Huber
.LONG TERM...
(Friday night to Thursday)
While the upper trough will be east of the region Friday night and
Saturday, a weakly capped atmosphere will remain. Therefore,
isolated, mainly afternoon and evening showers and thunderstorms
will continue to be possible. The upper ridge strengthens Sunday,
however, with hot and dry conditions expected through next week.
Highs are expected mainly in the mid 90s.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 72 93 72 96 73 / 40 30 20 20 10
San Angelo 73 94 72 96 74 / 30 30 20 20 10
Junction 73 93 73 95 74 / 20 20 20 20 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
04
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
850 PM EDT FRI AUG 29 2014
.SYNOPSIS...
A STALLED FRONTAL BOUNDARY NEAR THE SOUTH CAROLINA...NORTH
CAROLINA BORDER WILL MOVE GRADUALLY NORTH TONIGHT THROUGH
SATURDAY...AND BE POSITIONED OVER NORTHERN VIRGINIA BY SATURDAY
AFTERNOON. A MORE SUBSTANTIAL COLD FRONT WILL APPROACH THE AREA
SATURDAY NIGHT AND MOVE THROUGH THE AREA SUNDAY AND SUNDAY NIGHT.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 820 PM EDT FRIDAY...
EVENING SOUNDINGS SHOW MOISTURE TRAPPED BENEATH THE INVERSION AT
85H AIDED BY SHALLOW SE FLOW NORTH OF THE RESIDUAL FRONT TO THE
SOUTH. MOST INSTABILITY THIS EVENING REMAINS OVER THE FAR SW WHERE
STILL HAVE A FEW SHOWERS ONGOING NEAR THE FRONT. THUS LEAVING IN
SOME CHANCE POPS THERE A WHILE LONGER AS THE HRRR SHOWS SOME OF
THIS COVERAGE SLIDING NORTH THROUGH MIDNIGHT. OTRW SATELLITE
DEPICTING LOW CLOUDS SPREADING BACK NORTH FROM SOUTHERN VIRGINIA
ATTM AHEAD OF THE BOUNDARY THAT WILL LIFT SLOWLY BACK NORTH
OVERNIGHT. MOST LATEST MODEL SOLUTIONS SHOW LOW CLOUDS REMAINING
ALONG/EAST OF THE BLUE RIDGE THROUGH MORNING WITH ONLY THE FAR
SOUTH AND WEST STAYING MORE PC ALONG THE PERIMETER OF THE WEAK
WEDGE. SHOWER CHANCES ELSW REMAIN IFFY GIVEN LOSS OF HEATING WITH
THE BOUNDARY ACROSS THE REGION LATE. LATEST NAM AND TO SOME DEGREE
THE HRRR WANT TO DEVELOP A FEW SHRA CLUSTERS ALONG AND JUST EAST
OF THE BLUE RIDGE AFTER MIDNIGHT...WHILE MOST OTHERS DRY OR
FARTHER SOUTH WITH ISOLATED COVERAGE. SINCE ALREADY HAVE SOME
ISOLATED POPS GOING AND SEEING SOME INSTABILITY ABOVE THE
INVERSION...WILL LEAVE IN AND EXTEND INTO SOUTHSIDE VIRGINIA
OVERNIGHT. OTRW FOG/LOW CLOUDS LOOK ON TRACK WITH JUST SOME UPWARD
ADJUSTS TO LOW TEMPS GIVEN THE CLOUD CANOPY AND MOIST DEWPOINTS
OVERNIGHT.
WE EXPECT A BREAK IN THE PRECIPITATION SATURDAY MORNING WITH THE
FORCING ASSOCIATED WITH THE FRONT NORTH OF THE REGION.
HOWEVER...BY THE AFTERNOON...ENOUGH DAYTIME HEATING IS EXPECTED TO
REFIRE SHOWERS AND PERHAPS A FEW THUNDERSTORMS IN THE NORTHERN
PARTS OF THE REGION CLOSEST TO THE NEW LOCATION OF THE STALLED
FRONT. ALSO...INCREASING SOUTHERLY WINDS WILL FOCUS UPSLOPE
ISOLATED SHOWER AND THUNDERSTORM POTENTIAL ALONG THE CREST OF THE
BLUE RIDGE.
LOW TEMPERATURES TONIGHT WILL BE A MIX OF LOW TO MID 60S ACROSS THE
MOUNTAINS WITH MID TO UPPER 60S ACROSS THE PIEDMONT. ON
SATURDAY...HIGH TEMPERATURES IN THE LOW TO MID 80S WILL BE COMMON IN
THE MOUNTAINS WITH UPPER 80S TO NEAR 90 ACROSS THE PIEDMONT.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 330 PM EDT FRIDAY...
UPPER LEVEL RIDGE FORECAST OVER THE SOUTHEASTERN CONUS TO REMAIN IN
PLACE IN THE SHORT-TERM WITH THE MAIN WEATHER FEATURE A SERIES OF
SOUTHERN STREAM SHORT-WAVES EXPECTED TO TRACK FROM THE GULF COAST
NORTHEAST INTO THE OHIO VALLEY. 12Z MODEL RUNS OF GFS/NAM/EURO
SHOWING THIS FEATURE OR SERIES OF FEATURES TRACKING SOMEWHAT
FURTHER WEST THAN PREVIOUS RUNS DUE PARTLY TO THE STRONG RIDGE.
AXIS OF HEAVIEST RAINFALL SHOULD STAY WEST OF OUR CWA BUT STILL
HAVE LIKELY POPS IN THE FAR WEST ON SUNDAY TAPERING TO CHANCE
ACROSS THE PIEDMONT ON SUNDAY. RIDGE FLATTENS SOMEWHAT ON MONDAY
AS UPPER TROUGH ENERGY REMAINS WILL NORTH BUT WILL STILL BE
CHANCES FOR MAINLY AFTERNOON SHOWERS AND SCATTERED THUNDERSTORMS
MONDAY AFTERNOON. TEMPS WILL REMAIN WARM THROUGH THE PERIOD WITH
MAINLY 80S FOR HIGHS AND 60S FOR LOWS EVEN WITH CONSIDERABLE
CLOUDS ON SUNDAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 330 PM FRIDAY...
FLAT UPPER RIDGE IS EXPECTED TO DOMINATE OUR MID-WEEK WEATHER
PATTERN ACROSS THE CENTRAL APPALACHIAN AND MID-ATLANTIC REGION. THIS
SHOULD MAINTAIN SUMMER-LIKE TEMPERATURES THROUGH THE ENTIRE PERIOD
WITH HIGHS NEAR 90F IN THE PIEDMONT AND MID-80S IN THE MOUNTAINS
ALONG WITH NIGHT-TIME LOWS IN THE 60S TO LOW 70S. COULD END UP BEING
ONE OF THE WARMEST WEEKS OF THE SUMMER EVEN AS THE SO-CALLED
METEOROLOGICAL SUMMER ENDS ON AUGUST 31. PRECIPITATION WILL ALSO
GENERALLY BE OF SUMMER-LIKE CHARACTER WITH DIURNALLY DRIVEN
CONVECTION PROVIDING THE BEST CHANCES FOR RAINFALL. WEDNESDAY
AFTERNOON LOOKS LIKE THE MOST PROMISING DAY FOR STORMS AS WEAK
FRONTAL BOUNDARY PUSHES ACROSS THE CWA. THURSDAY AND FRIDAY LIKELY
TO BE DRIER ALTHOUGH WIDELY SCATTERED SHOWERS STILL POSSIBLE.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 645 PM EDT FRIDAY...
VISIBILITY SENSOR AT KDAN REMAINS INOPERABLE. PARTS ARE ON
ORDER. UNTIL REPAIRS COMPLETE...NO AMENDMENTS WILL BE SCHEDULED.
ISOLATED SHOWERS AND STORMS...MAINLY SW OF KBLF HAVE ALL BUT FADED
THIS EVENING WITH OUTFLOW DRIVEN ADDITIONAL SHRA HOW FARTHER WEST.
HOWEVER STILL SOME POTENTIAL TO SEE A FEW ADDED SHRA DEVELOP
MAINLY SW SO MAY LEAVE IN A VCSH MENTION AT KBLF OVER THE NEXT
HOUR OR TWO.
OTRW MAIN CONCERN OVERNIGHT WITH THE DEVELOPMENT OF LOW CIGS AND
FOG AS THE WEAK FRONT TO THE SOUTH SLIDES NORTH INTO THE AREA BY
MORNING. MODELS SHOW A FEW SHRA DEVELOPING ACROSS THE CENTRAL AND
NORTH LATE TONIGHT BUT IFFY GIVEN LACK OF INSTABILITY AND AFTER
LOSS OF HEATING. LOW LEVEL MOISTURE WILL INCREASE AND BECOME
TRAPPED UNDER THE INVERSION ALOFT. ANTICIPATE MOST OF THE REGION
TO DEVELOP MVFR CIGS WITH SOME REGIONS OF IFR PER LATEST NAM.
VSBYS WILL ALSO DECREASE WITH MOST AREAS HAVING MVFR WITH POCKETS
OF IFR NEAR THE BLUE RIDGE. HOWEVER GIVEN CURRENT TRENDS OFF
SATELLITE IN ALREADY SEEING CLOUDS PUSH NORTH ACROSS EASTERN
SECTIONS...WILL INTRODUCE MVFR CIGS A BIT SOONER THERE BUT DELAY
SOME FROM KBCB WESTWARD WHERE THINGS ARE MORE MIXED.
ANY SUB-VFR CONDITIONS WILL BE FAIRLY SLOW TO IMPROVE TO VFR AFTER
SUNRISE SATURDAY. 15Z/11AM IS THE MOST LIKELY TIME MOST OF THE
REGION WILL BE BACK TO VFR BUT MAY TAKE UNTIL MID AFTERNOON FOR
KROA/KLYH TO IMPROVE. THINK MOST SHOULD FINALLY GO TO A SCATTERED
CU FIELD ONCE LOW CIGS IMPROVE WITH ANY CONVECTION VERY ISOLATED
GIVEN THE FRONT TO THE NE.
EXTENDED DISCUSSION...
ANY ISOLATED OR SCATTERED SHOWERS AND STORMS WILL BE MAINLY
CONFINED TO AN AREA ALONG AND NORTH OF A KHSP-KFVX LINE SATURDAY
EVENING...JUST SOUTH OF THE AGAIN STALLED FRONTAL BOUNDARY.
LATE SATURDAY NIGHT THROUGH SUNDAY EVENING AN AREA OF LOW PRESSURE
WILL HEAD EASTWARD THROUGH THE GREAT LAKES REGION TOWARD NEW
ENGLAND. ITS ASSOCIATED COLD FRONT WILL SWEEP THROUGH THE REGION
BRINGING A GENEROUS COVERAGE OF SHOWERS AND SOME STORMS. SUB-VFR
CONDITIONS ARE EXPECTED TO ACCOMPANY THE SYSTEM AND PRECIPITATION.
ANOTHER COLD FRONT IS EXPECTED TO PRODUCE SIMILAR CIRCUMSTANCES
TUESDAY INTO WEDNESDAY. HOWEVER...MODEL GUIDANCE FOR THIS ONE
OFFERS PRECIPITATION IN A MORE SCATTERED DISTRIBUTION. AS
SUCH...THE MAGNITUDE OF SUB-VFR CONDITIONS MAY BE LESS.
&&
.EQUIPMENT...
AS OF 730 AM EDT FRIDAY ...
THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WILL
BE OUT OF SERVICE UNTIL FURTHER NOTICE. A PART HAS BEEN BACK-ORDERED.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...DS
NEAR TERM...DS/JH
SHORT TERM...PC
LONG TERM...PC
AVIATION...DS/JH
EQUIPMENT...AMS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
143 AM EDT THU AUG 28 2014
.SYNOPSIS...
A WEAK COLD FRONT WILL MOVE SOUTH INTO THE REGION TONIGHT AND
STALL ACROSS OUR AREA THROUGH THURSDAY AND FRIDAY...PROVIDING THE
FOCUS FOR SCATTERED SHOWERS AND THUNDERSTORMS. THE FRONT WILL
LIFT NORTH AGAIN FRIDAY NIGHT.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 945 PM EDT WEDNESDAY...
WATCHING A BROKEN LINE OF THUNDERSTORMS APPROACHING FROM THE
NORTHWEST. HRRR 23Z RUN SHOWS SOME OF THIS ACTIVITY REACHING
WESTERN GREENBRIER COUNTY. ADDED SLIGHT CHANCE TO CHANCE POPS FOR
THE NEXT FEW HOURS ALONG WITH ADDING THUNDER TO THE GRIDS. BUMPED
UP CLOUD COVER ACROSS THIS AREA AS WELL.
AS OF 225 PM EDT WEDNESDAY...
NOT SEEING MUCH IN THE WAY OF SHRA DEVELOPMENT THIS AFTERNOON.
BEST CU FIELD LIES FROM THE MTNS OF GREENBRIER COUNTY NEWD ALONG
THE ALLEGHANY FRONT. INSTABILITY IS MARGINAL WITH BEST SITUATED
ACROSS KY INTO OHIO AND PA. WILL KEEP ISOLATED THREAT OF SHRA/TSRA
THIS EVENING ACROSS THE WRN FRINGES OF SE WV/FAR SW VA AND BATH
VA. MAINLY LOOKING AT CLEAR SKIES ELSEWHERE BUT MOISTURE IS
STARTING TO INCREASE AS NOTED BY DEWPOINTS ASCENDING INTO THE 60S.
LOW TEMPS AS SUCH ARE GOING TO BE MILDER THAN PREVIOUS SEVERAL
NIGHTS WITH LOWS IN THE MID TO UPPER 50S MOUNTAIN VALLEYS TO MID 60S
PIEDMONT.
BACKDOOR FRONT WILL SHIFT ACROSS THE VA/NC BORDER LATE TONIGHT/THU
MORNING. MODELS SHOW AXIS OF CONVERGENCE TO ALIGN ACROSS THE NC MTNS
INTO THE PIEDMONT OF VA TOMORROW AFTERNOON AND THIS WILL BE WHERE
TSRA WILL FORM...BUT COVERAGE WILL BE SCATTERED AT BEST...SO KEPT
POPS IN THE 20/30 RANGE. MAINLY DRY NORTH OF A BLF-ROA LINE.
CLOUDS WILL BE SCATTERED/BKN AFTER ANY MORNING FOG LIFTS...WITH
HIGHS SURGING INTO THE 80S MOST AREAS WITH LOWER 90S SOUTHEAST.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
AS OF 330 PM EDT WEDNESDAY...
MODELS ARE IN GOOD AGREEMENT THAT A WEAK FRONT WILL BE STALLED
ACROSS NORTHERN NORTH CAROLINA THURSDAY NIGHT AND FRIDAY...PROVIDING
THE FOCUS FOR SHOWER ACTIVITY...POSSIBLY WITH A FEW THUNDERSTORMS
DEVELOPING FRIDAY AFTERNOON/EVENING WITH DAYTIME HEATING. CANNOT
IDENTIFY WITHIN THE MODEL DATA ANY STRONG DISTURBANCES RIDING ALONG
THE FRONT...SO BELIEVE THE RAINFALL WILL BE OF THE LIGHT AND
OCCASIONAL VARIETY.
LOW PRESSURE PASSING ACROSS THE GREAT LAKES WILL DRAW THE FRONTAL
BOUNDARY BACK TO THE NORTH AS A WARM FRONT FRIDAY NIGHT...WITH WEAK
HIGH PRESSURE BUILDING BACK ACROSS OUR AREA ON SATURDAY FROM THE
CAROLINAS. CANNOT RULE OUT A FEW SHOWERS OR STORMS DEVELOPING ACROSS
THE MOUNTAINS DURING SATURDAY AFTERNOON AND EVENING...BUT THE DIP IN
ATMOSPHERIC MOISTURE ASSOCIATED WITH THE HIGH WILL KEEP THIS
ACTIVITY RATHER ISOLATED.
SATURDAY NIGHT...SOUTHWESTERLY FLOW WILL BECOME FIRMLY REESTABLISHED
AS UPPER LEVEL RIDGING RESIDES ACROSS THE SOUTHEAST STATES...WHILE
AN UPPER LEVEL TROUGH MOVES TOWARDS THE GREAT LAKES. AS SUCH...
EXPECT ATMOSPHERIC MOISTURE TO RAMP UP OVERNIGHT THANKS TO A DIRECT
WINDS OFF THE GULF OF MEXICO. CLOUD COVER WILL INCREASE AFTER
SUNSET...WITH A FEW SHOWERS ENTERING THE MOUNTAINS TOWARD SUNRISE
SUNDAY.
TEMPERATURES THROUGH THE PERIOD WILL BE CLOSER TO NORMAL FOR LATE
AUGUST THANKS TO INCREASED CLOUD COVER/MOISTURE POOLING ALONG THE
FRONT. LOOK FOR HIGHS TO REACH INTO THE 80S MOST LOCATIONS FRIDAY
AND SATURDAY...WHILE OVERNIGHT LOWS WILL BE MILDER THAN PREVIOUS
NIGHTS...GENERALLY HOLDING IN THE 60S.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 345 PM EDT WEDNESDAY...
DEEP GULF MOISTURE FLOWING NORTH ALONG THE APPALACHIAN CHAIN WILL
MAINTAIN A CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY FOR THE
EARLY HALF OF NEXT WEEK.
FOR SUNDAY...RAINFALL IS LOOKING INCREASINGLY LIKELY AS AN
UPPER LEVEL TROUGH MOVES UP THE OHIO RIVER VALLEY. WITH
PERCEPTIBLE WATER VALUES IN THE BALLPARK OF 2 INCHES ACROSS OUR
AREA...BELIEVE THAT LOCALLY EXCESSIVE RAINFALL WILL BE POSSIBLE IN
SOME AREAS... ESPECIALLY IF STORMS BEGIN TO PASS REPEATEDLY OVER
THE SAME LOCATIONS.
ON MONDAY...UPPER LEVEL FLOW BEGINS TO TRANSITION TO A MORE WEST TO
EAST ORIENTATION...WITH NO STRONG DISTURBANCES EXPECTED. BELIEVE
SHOWER AND THUNDERSTORM ACTIVITY WILL BE MORE DRIVEN BY DAYTIME
HEATING THAN ANYTHING ELSE...MEANING RAINFALL WILL BE MORE OF THE
HIT AND MISS VARIETY.
LOOKING TO TUESDAY...EXPECT A SLIGHTLY BETTER CHANCE OF SHOWERS AND
THUNDERSTORMS AS A COLD FRONT APPROACHES OUR REGION FROM THE
NORTHWEST. BEST CHANCES FOR SHOWER AND THUNDERSTORM ACTIVITY WILL BE
DURING THE EVENING AS THE FRONT APPROACHES THE OHIO RIVER...HOWEVER
WITH NO REAL PUSH OF COLD AIR BEHIND THE FRONT...IT IS ENTIRELY
POSSIBLE THAT THE OHIO RIVER IS AS FAR SOUTH AS THE FRONT SINKS.
ABUNDANT GULF MOISTURE WILL MAKE FOR MUGGY AND WARM CONDITIONS FOR
THE EARLY HALF OF NEXT WEEK. LOOK FOR HIGHS TO RANGE FROM THE UPPER
70S/LOW 80S ACROSS THE MOUNTAINS...TO THE UPPER 80S ACROSS THE
PIEDMONT. OVERNIGHT LOWS WILL RANGE FROM THE MID 60S TO LOW 70S.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 135 AM EDT THURSDAY...
CLUSTER OF SHOWERS AND THUNDERSTORMS WAS MOVING SOUTH THROUGH
WEST VIRGINIA...JUST TO THE WEST OF THE KLWB AND KBLF AIRPORT.
EXPECT PRECIPITATION TO WEAKEN AS IT CONTINUES TO MOVE SOUTH.
AMOUNT OF FOG EARLY THIS MORNING WILL DEPEND ON THE CLOUD COVER
MOVING THROUGH THE AREA. HAVE DELAYED THE TIMING ON LIFR FOG AT
KLWB. LOWER CONFIDENCE OF FORMATION OF IFR OR LIFR FOG AT KBCB
WITH THE MID LEVEL CLOUDS APPROACHING.
WEAK SURFACE COLD FRONT WILL CROSS THE FORECAST AREA EARLY
TODAY...THEN BECOME STATIONARY ACROSS NORTH CAROLINA TONIGHT.
CONVERGENCE ALONG THE FRONT WILL PERMIT SCATTERED SHRA/TSRA AGAIN
THIS AFTERNOON. POSITION OF FRONT BY THAT TIME SUGGESTS SHRA/TSRA
ACTIVITY WILL DEVELOP VCNTY OF THE VA/NC BORDER...THEN DRIFT
SOUTHEAST INTO NORTH CAROLINA WITH THE MEAN WIND WHICH WILL BE OUT
OF THE NORTHWEST. FOR NOW HAVE LEFT ANY SHOWERS AND THUNDERSTORMS
OUT OF THE KDAN TAF.
EXTENDED DISCUSSION...
THE WEAK FRONT IS FORECAST TO RETURN NORTH AS A WARM FRONT
SATURDAY. WIDELY SCATTERED SHRA/TSRA ARE EXPECTED ALONG THIS
BOUNDARY FRIDAY AND SATURDAY...WITH THE GREATEST COVERAGE DURING
THE PEAK HEATING OF THE DAY. WHERE SHRA/TSRA OCCUR BRIEF PERIOD OF
SUB VFR CONDITIONS CAN BE EXPECTED.
AN AREA OF LOW PRESSURE IS FORECAST TO MOVE THROUGH THE GREAT
LAKES SATURDAY NIGHT AND SUNDAY...THE ASSOCIATED COLD FRONT
TRAILING SOUTH AND MOVING ACROSS THE OHIO/TN VALLEYS. SHOWERS AND
THUNDERSTORMS WILL LIKELY BE ASSOCIATED WITH THIS FRONT...THIS
ACTIVITY SPREADING EAST INTO THE CENTRAL APPALACHIANS SUNDAY AND
MONDAY. SHOWER COVERAGE SUNDAY/MONDAY IS EXPECTED TO BE MUCH MORE
WIDESPREAD AS COMPARED TO FRIDAY AND SATURDAY.
&&
.EQUIPMENT...
AS OF 1130 AM EDT WEDNESDAY ...
THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL
AIRPORT...REMAINS OUT OF SERVICE. A PART HAS BEEN ORDERED BUT
APPEARS REPAIRS WILL NOT BE DONE UNTIL THIS FRIDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WP
NEAR TERM...CF/WP
SHORT TERM...NF
LONG TERM...NF
AVIATION...AMS/PM
EQUIPMENT...AMS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
329 PM CDT THU AUG 28 2014
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 329 PM CDT THU AUG 28 2014
MAIN FOCUS FOR THE NEXT 24 TO 48 HOURS IS ON THE HEAVY RAINFALL
POTENTIAL AS A FEW ROUNDS OF STORMS LIFT THROUGH THE UPPER
MISSISSIPPI RIVER VALLEY.
AS OF MID AFTERNOON...WATER VAPOR IMAGERY OVERLAID WITH RAP 500MB
RAP HEIGHTS SHOWED THE SHORTWAVE TROUGH PUSHING OFF THE COLORADO
ROCKIES WITH WEAK IMPULSES LIFTING THROUGH THE CENTRAL PLAINS
TOWARD THE UPPER MIDWEST. ONE SUCH WAVE IS BRINGING THE SHIELD OF
MAINLY RAIN SHOWERS THIS AFTERNOON...WHILE ANOTHER ONE IS NOTED
NEAR THE TX PANHANDLE INTO SOUTHERN KANSAS. THIS ONE...ALONG WITH
THE MAIN TROUGH...WILL BE OUR PLAYER FOR FRIDAY AFTERNOON AND
EVENING.
THE SURFACE HIGH PRESSURE ANCHORED OVER THE GREAT LAKES KEPT FLOW
OF DRIER AIR...LIMITING THE FORWARD PROGRESS OF RAIN SHIELD. A LOT
OF THE MOISTURE WENT INTO SATURATION...AND COMBINED WITH THE
WEAKENING LLJ MOISTURE TRANSPORT FROM THIS MORNING...THE HEAVIER
RAINFALL DID NOT MATERIALIZE. WITH THAT SAID...THE ENVIRONMENT
WILL BEGIN TO BECOME MORE FAVORABLE TONIGHT AND RECENT 1-HR
RAINFALL TOTALS HAVE BEEN GENERALLY 0.1 TO 0.2 INCH...WITH SOME
ISOLATED 0.3-0.5 AMOUNTS.
VERY LITTLE INSTABILITY FOUND ACROSS THE AREA WHICH IS KEEPING
ACTIVITY AS SHOWERS/RAIN. WENT AHEAD AND LIMITED THUNDER CHANCES
TO ISOLATED/SCATTERED THROUGH THE OVERNIGHT HOURS...ESPECIALLY
MN/WI AREAS. IT WILL BE MORE STEADY RAINFALL. AS THE CURRENT
SHIELD OF RAIN LIFTS NORTHEAST...EXPECTING THE BACK EDGES TO FILL
IN SOME KEEPING THE HIGHER POPS IN PLACE THROUGH THE OVERNIGHT.
THE TIMING OF ANY SPECIFIC UPPER LEVEL WAVES...WITH CONFLICTING
STRENGTH IN MOISTURE TRANSPORT AND SURFACE FOCUS...LENDS A BIT
LOWER CONFIDENCE IN WHERE HEAVIEST RAINFALL WILL FALL. WHAT HAS
HIGHER CONFIDENCE IS THAT THE ATMOSPHERE SHOULD BETTER PRIMED FOR
EFFICIENT RAIN PRODUCERS. NO CHANGES TO THE IDEA THAT PWATS ARE
HIGH...WARM CLOUD DEPTHS ARE ABOVE 4 KM...AND THERE IS A
CONTINUOUS FLOW OF MOISTURE STREAMING IN FROM THE SOUTHWEST IN
ADVANCE OF THE SHORTWAVE.
PERUSAL OF 28.12Z MODELS SHOW SIGNALS FOR ANOTHER IMPULSE TO
SPARK CONVECTION OVERNIGHT ACROSS WESTERN INTO SOUTHWEST IOWA.
THIS WOULD LIFT THROUGH NORTHEAST IOWA AND SOUTHEAST MINNESOTA
EARLY MORNING. AFTER THE MORNING LLJ WEAKENS...THERE SEEMS TO NOT
BE ANOTHER KICKER UNTIL LATE FRIDAY AFTERNOON AND EVENING. AS
SUCH...THE LATE MORNING AND EARLY AFTERNOON HOURS COULD END UP
DRIER...AND HAVE TRIED TO REFLECT THIS THINKING IN THE HOURLY
POPS.
THE MORE SIGNIFICANT WAVE ARRIVES FRIDAY AFTERNOON THROUGH THE
EARLY MORNING HOURS SATURDAY. FINALLY THE MAIN SHORTWAVE TROUGH
ENERGY WILL BE FELT...AND WITH A GOOD FEED OF MOISTURE TRANSPORT
AND WARM AIR ADVECTION...THERE SHOULD BE WIDESPREAD SHOWERS AND
ISOLATED/EMBEDDED THUNDERSTORMS THROUGHOUT FROM LATE AFTERNOON
ONWARD.
ALTHOUGH THE FAVORABLE ATMOSPHERIC CONDITIONS WILL BE IN PLACE
FOR HEAVY RAINFALL TOMORROW...THE LACK OF HIGHER RAINFALL TOTALS
TODAY DAMPENS THE OVERALL FLASH FLOODING THREAT. RAINFALL TOTALS
THROUGH SATURDAY HAVE BEEN TEMPERED A BIT...AND ARE MORE IN THE
1-2 INCH RANGE. A LOT OF THE AREA CAN TAKE THIS TYPE OF RAINFALL.
OF COURSE LOCALLY HIGHER AMOUNTS WILL BE POSSIBLE...BUT FEEL THE
OVERALL THREAT IS REDUCED COMPARED TO THE THINKING IN THE PAST 24
HOURS.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 329 PM CDT THU AUG 28 2014
THE MAIN FOCUS IN THE LONG TERM IS CENTERED ON THE THREAT FOR
SEVERE WEATHER SUNDAY NIGHT INTO MONDAY. WITH THE HOLIDAY WEEKEND
APPROACHING...AND WITH MANY FOLKS PLANNING OUTDOOR ACTIVITIES...IT
IS THIS PERIOD THAT WARRANTS CLOSE WATCHING.
IN THE UPPER LEVELS...THE 28.12Z GUIDANCE FOLLOWED THE PAST
SEVERAL MODEL CYCLES IN SHOWING A DIGGING WESTERN CONUS LONGWAVE
TROUGH APPROACHING THE NORTHERN PLAINS BY SUNDAY EVENING. 250MB
JET DYNAMICS PUTS THE AREA IN A FAVORABLE RIGHT ENTRANCE
REGION...AND THIS JET STRENGTHENS BETWEEN 00-06Z MONDAY.
AT THE SURFACE...A COLD FRONT LOOKS LIKELY TO MOVE ACROSS
MINNESOTA LATE SUNDAY NIGHT...REACHING THE MISSISSIPPI RIVER EARLY
MONDAY MORNING. MUCAPE RANGES FROM 1500 TO 2000 J/KG ACROSS THE
REGION LATE SUNDAY...WITH HEALTHY PROFILES AS NCAPE VALUES
APPROACH 0.15. THIS IS AIDED BY 700-500MB LAPSE RATES AROUND
7.5C/KM. THE SHEAR ENVIRONMENT IS A BIT MUDDLED BETWEEN THE
VARIOUS GUIDANCE...BUT OVERALL 0-3KM SHEAR VALUES RANGE FROM 20 TO
30 KTS. HODOGRAPHS SHOW SOME CURVATURE BUT A LOT OF THE SHEAR IS
SPEED RELATED. OVERALL...THE CURRENT TIMING WOULD SUGGEST
CONVECTION TO DEVELOP IN THE AFTERNOON ACROSS THE EASTERN DAKOTAS
/ WESTERN INTO CENTRAL MINNESOTA...POSSIBLY AS SUPERCELLS...THEN
MERGE IN LINE SEGMENTS TOWARD THE WESTERN CWA IF MAINTAINED.
THERE ARE STRONG MOISTURE TRANSPORT SIGNALS WITH HIGHER PWATS
RETURNING...SO THERE COULD BE SOME HEALTHY RAIN PRODUCERS. THE
MAIN LIMITING FACTOR WOULD BE STORM SPEED...WHICH SHOULD BE RATHER
PROGRESSIVE. REGARDLESS...MAIN THREATS LOOK TO BE HEAVY
RAIN...DAMAGING WINDS...AND LARGE HAIL. AT THIS TIME...GIVEN
TIMING...WEST OF THE MS RIVER WOULD BE MORE FAVORABLE AND THIS
LINES UP WELL WITH THE CURRENT DAY 4 OUTLOOK FROM THE SPC.
OVERALL...WILL NEED TO WATCH THIS PERIOD.
THE FRONT SLIDES INTO WESTERN WISCONSIN MONDAY MORNING...WHICH
MAY ALLOW FOR ANOTHER ROUND OF DESTABILIZATION AND STRONG STORMS
FOR OUR EASTERN AREAS MONDAY AFTERNOON. THAT IS A BIT MORE
UNCERTAIN BUT IF THE SYSTEM SLOWS DOWN...WHICH SEEMS TO BE A
TREND...THIS PERIOD MAY NEED TO BE WATCHED CLOSER.
THE TUESDAY-THURSDAY PERIOD LOOKS TO FEATURE ZONAL UPPER LEVEL
FLOW WITH THE POSSIBILITY OF A FEW RIPPLES SLIDING THROUGH. NOT
MUCH CONSISTENCY IN THE MODEL RUNS TO ADD ANY DETAILS AT THIS
POINT. LOTS OF WEATHER TO GET THROUGH UNTIL THEN. SLIGHT CHANCES
WITH SEASONABLE TEMPERATURES LOOKS GOOD AT THIS POINT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1225 PM CDT THU AUG 28 2014
TREND OF CONDITIONS IS DOWNWARD THIS PERIOD AS A VERY MOIST AIRMASS
AND A COUPLE ROUNDS OF FORCING/LIFT SPREAD ACROSS MN/IA/WI WITH IT.
FIRST ROUND OF -RA WAS SPREADING NORTHEAST ACROSS THE AREA LATE THIS
MORNING/EARLY THIS AFTERNOON...AND MARKED THE LEADING EDGE OF LOWER
VFR OR MVFR CIGS ALONG WITH SOME MVFR VSBYS IN -RA/-SHRA.
INSTABILITY HAS BEEN LIMITED SO FAR...THUS NOT MUCH FOR TSRA/CB
EXPECTED AT THE TAF SITES THRU THIS AFTERNOON/TONIGHT. IFR CIGS WERE
DEVELOPING ALONG/WEST OF I-35 ACROSS SOUTHERN MN/NORTHERN IA...
BEHIND THE LEADING BAND OF -RA. THESE LOW CLOUDS/CIGS EXPECTED TO
SPREAD EAST/NORTHEAST ACROSS THE TAF SITES TONIGHT AND PERSIST
THROUGH AT LEAST FRI MORNING...ALONG WITH SOME PERSISTENT -SHRA. MAY
YET NEED A PERIOD OR 2 OF TSRA AT EITHER KRST OR KLSE BETWEEN 00Z
AND 18Z...BUT CONFIDENCE IN TIMING IS LOW AT THIS POINT AND DID NOT
WANT TO PUT IN A LONGER PERIOD OF VCTS/CB IN THE TAFS FOR NOW.
&&
.HYDROLOGY...THROUGH SATURDAY MORNING
ISSUED AT 329 PM CDT THU AUG 28 2014
WITH LESS THAN EXPECTED RAINFALL TODAY...OVERALL TOTALS THROUGH
SATURDAY HAVE BEEN REDUCED TO THE 1.5 TO 2.5 INCH RANGE. THE SURGE
IN EFFICIENT RAIN PRODUCING ATMOSPHERIC CONDITIONS...CHARACTERIZED
BY WARM CLOUD DEPTHS 3.5 TO 4.0 KM...PWATS 1.5 TO 2.0 INCHES...AND
LOWER 70F DEWPOINTS...WILL REMAIN IN PLACE THROUGH EARLY SATURDAY.
OVERALL...THE THREAT FOR EXCESSIVE RAINFALL HAS BEEN DIMINISHED A
BIT AS THE ROUNDS OF STORMS LOOK PROGRESSIVE ENOUGH AND MUCH OF
THE AREA CAN HANDLE THE EXPECTED AMOUNTS. AS SUCH...WILL CONTINUE
THE HYDROLOGIC OUTLOOK /ESFARX/
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM....ZT
AVIATION.....RRS
HYDROLOGY....ZT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1136 PM CDT WED AUG 27 2014
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 328 PM CDT WED AUG 27 2014
FORECAST FOCUS IS ON PRECIPITATION TIMING AND AMOUNTS...THREAT
FOR HEAVY RAIN WITH LOCALIZED FLOODING.
AS OF MID AFTERNOON...WATER VAPOR IMAGERY OVERLAID WITH RAP 500
MB HEIGHTS SHOWED DECAYING DISTURBANCE ACROSS IOWA...WITH MAIN
CLOSED LOW ROTATING INTO NORTHWESTERN COLORADO. WEAK IMPULSES WERE
RIDING THE PERIPHERY OF THE TROUGH...AND IT IS THESE IMPULSES THAT
WILL BE THE PLAYERS FOR THE NEXT 24 TO 48 HOURS ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY.
AT THE SURFACE...LINGERING SHOWERS AND THUNDERSTORMS HAVE BEEN
CONFINED TO SOUTHERN AND SOUTHWESTERN IOWA...KEEPING FRONTAL
BOUNDARY ACROSS SOUTHERN IOWA / NORTHERN MISSOURI. THE 65F
DEWPOINT LINE IS GENERALLY SOUTH OF I-80.
THE LARGEST CHANGES TO ONGOING FORECAST HAVE BEEN RELATED TO
PRECIPITATION TIMING...AS 27.12Z MODEL CYCLES TREND TOWARD A LATER
ARRIVAL OF THE GREATEST 850MB MOISTURE TRANSPORT OVERNIGHT THROUGH
THE DAY ON THURSDAY. MOST OF THE DETERMINISTIC AND HI-RES MODELS
SHOW A SHIELD OF RAIN SHOWERS WITH EMBEDDED THUNDERSTORMS REACHING
NORTHEAST IOWA / SOUTHEAST NOT UNTIL THE EARLY MORNING HOURS /4 TO
6 AM/ THEN MOVING INTO WESTERN WISCONSIN MID TO LATE MORNING.
PRECIPITATION CHANCES HAVE BEEN ADJUSTED...BUT OVERALL CONFIDENCE
REMAINS VERY HIGH SO KEPT 90 TO 100 CHANCES.
THE NOSE OF THE 850MB MOISTURE TRANSPORT LIFTS THROUGH THE AREA
DURING THE DAY...SO ANY COMPLEX OF SHOWERS/STORMS WILL LIKELY BE
PROGRESSIVE. HOWEVER...THE ATMOSPHERE WILL INCREASINGLY BECOME
MORE FAVORABLE FOR HEAVY RAINFALL RATES...AS PWATS APPROACH 2
INCHES. WARM CLOUD DEPTHS EXCEED 4 KM ACROSS MUCH OF THE AREA. THE
STORM TOP WINDS ARE PROGGED TO BE 25 TO 30 KTS...WHICH SHOULD HELP
KEEP CONVECTION PROGRESSIVE ENOUGH. THOUGH WITH BROAD WARM AIR
ADVECTION AND ISENTROPIC LIFT DURING THE DAY...HAVE KEPT HIGH
PRECIPITATION CHANCES THROUGH THE EVENING HOURS. THE GREATER FOCUS
SEEMS TO BE ON WESTERN INTO NORTH CENTRAL WISCONSIN...THOUGH MOST
AREAS WILL SEE SHOWERS/STORMS THROUGHOUT THE DAY.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 328 PM CDT WED AUG 27 2014
THE MAIN 500MB SHORTWAVE BEGINS TO SWING THROUGH THE UPPER
MIDWEST FRIDAY EVENING INTO SATURDAY MORNING...WITH THE GREATEST
500-300MB PV ADVECTION ALIGNED FROM CENTRAL AND EASTERN IOWA INTO
SOUTHERN WISCONSIN. THE MOIST AIRMASS WILL LINGER THROUGH THIS
PERIOD AS WELL...AS THE OVERALL ENVIRONMENT SUPPORTS EFFICIENT
RAIN PRODUCES. THE SURFACE FRONT WILL LIKELY STALL FROM IOWA INTO
SOUTHERN WISCONSIN AND COULD BE THE FOCUS FOR SEVERAL EPISODES FOR
SHOWERS/STORMS. DEPENDING ON THE HEAVY RAINFALL OUTCOME IN ROUND
ONE...THIS PERIOD WILL NEED TO BE WATCHED FOR REPEATED ROUNDS.
THOUGH AT THIS POINT...IT LOOKS LIKE DIFFERENT AREAS WILL SEE THE
ROUNDS OF HEAVIER RAINFALL.
IT DOES LOOK LIKE BY SATURDAY MOST OF THE UPPER LEVEL ENERGY
MOVES EAST...AND THE PRECIPITATION CHANCES ARE CONFINED TO
SOUTHERN AND CENTRAL WISCONSIN. FOR THOSE PLANNING ACTIVITIES THIS
UPCOMING HOLIDAY WEEKEND...THE SATURDAY NIGHT TO SUNDAY MORNING
TIMEFRAME HAS THE GREATEST LIKELIHOOD TO SEE DRIER PERIODS.
SUNDAY THROUGH MONDAY WILL FEATURE AN APPROACHING UPPER LEVEL
SHORTWAVE FROM THE NORTHERN PLAINS. 27.12Z MODELS ALREADY SHOW
THIS FEATURE TO BE A BIT VIGOROUS AS IT SWINGS THROUGH. AT THE
SURFACE...THIS WILL DRIVE A COLD FRONT THROUGH THE UPPER MIDWEST.
THERE REMAINS SOME TIMING DIFFERENCES BETWEEN THE GFS/ECMWF/GEM
BUT THE TREND HAS BEEN FOR THE FRONTAL PASSAGE TO BE LATE SUNDAY
NIGHT OR EARLY MONDAY MORNING. SEVERE CHANCES LOOK LIMITED RIGHT
NOW GIVEN TIMING BUT 500 TO 1000 MUCAPE TRANSLATES AHEAD OF THE
FRONT WITH MARGINAL 0-6KM SHEAR VALUES /20 KTS/. SOMETHING TO KEEP
AN EYE WITH THE HOLIDAY WEEKEND...ESPECIALLY IF THE TIMING BECOMES
MORE FAVORABLE DURING PEAK HEATING.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1136 PM CDT WED AUG 27 2014
28.00Z FORECAST GUIDANCE CONTINUED ON THE TREND OF SLOWING
NORTHEASTWARD PROGRESS OF SHOWERS AND THUNDERSTORMS...SO DELAYED
-SHRA ANOTHER HOUR OR TWO...IMPACTING KRST BY 28.15Z AND KLSE BY
28.17Z. SHOWERS (HEAVY AT TIMES) WILL DOMINATE...BUT STILL EXPECT
SOME EMBEDDED THUNDER...SO WILL KEEP AFTERNOON TEMPO GROUPS TO
HIGHLIGHT POTENTIAL THREAT. VFR CONDITIONS TO PERSIST OVERNIGHT
INTO THURSDAY MORNING...BUT MVFR CEILINGS/VISIBILITY EXPECTED
WITH HEAVIER SHOWERS AND THUNDERSTORMS LATER IN THE DAY. WINDS
THROUGH THE PERIOD WILL REMAIN LIGHT...GENERALLY VARIABLE OR FROM
THE SOUTHEAST.
&&
.HYDROLOGY...THURSDAY THROUGH FRIDAY NIGHT
ISSUED AT 328 PM CDT WED AUG 27 2014
VERY FAVORABLE SETUP FOR EFFICIENT...HEAVY RAIN PRODUCERS OVER
THE NEXT FEW DAYS. WARM CLOUD DEPTHS CONTINUE TO HOVER NEAR 4000 M
/IF NOT HIGHER/ WHILE PWATS PEAK AROUND 2 INCHES THURSDAY-
THURSDAY NIGHT. HEAVIER RAIN SIGNALS ARE PROGRESSIVE...THROUGH
NORTHERN IOWA INTO SOUTHEAST MINNESOTA AND THEN NORTH CENTRAL
WISCONSIN. FOR ROUND TWO...THE HIGHER THREAT LOOKS TO BE ACROSS
EASTERN IOWA INTO SOUTHERN WISCONSIN.
RUN TOTAL QPF FROM THE EC/GFS/GEM THROUGH SATURDAY RANGE FROM 2
TO 4 INCHES. LOCALLY HIGHER AMOUNTS ARE LIKELY. AT THIS
MOMENT...THINK THERE COULD BE QUICK RISES ON SOME RIVERS...BUT
SHOULD STAY WITHIN BANK. AS ALONG AS STORMS MOVE...AND AREAS DON/T
GET REPEATED HITS...THE FLASH FLOOD THREAT IS REDUCED. ALL
SAID...WITH THE HIGH LIKELIHOOD OF HEAVY RAIN...AND THE POTENTIAL
FOR SIGNIFICANT AMOUNTS...WILL MAINTAIN HYDROLOGIC OUTLOOK TO
HIGHLIGHT THE THREATS. A FLASH FLOOD WATCH MAY BE NECESSARY IF
SIGNALS ARE FOR THE ROUNDS OF HEAVY RAINFALL LOOK TO REPEAT OVER
THE SAME AREA.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM....ZT
AVIATION...ROGERS
HYDROLOGY....ZT/RIECK
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
905 PM MDT FRI AUG 29 2014
.UPDATE...
ISSUED AT 904 PM MDT FRI AUG 29 2014
UPDATED THE GRIDS TO REMOVE ALL MENTION OF SHOWERS AND THUNDERSTORMS
OVERNIGHT BASED ON RADAR TRENDS AND LATEST MODEL GUIDANCE. ALSO
ADJUSTED TEMPERATURES...DEWPOINTS...WINDS AND CLOUD COVER BASED
ON TRENDS.
UPDATE ISSUED AT 600 PM MDT FRI AUG 29 2014
GRIDDED FORECASTS UPDATED TO MODIFY THE EVENING POPS WITH ISOLATED
THUNDERSTORMS FROM SARATOGA TO CHEYENNE...THEN DRY AFTER 9 PM.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 150 PM MDT FRI AUG 29 2014
A WELL-DEFINED SHORTWAVE CONTINUES TO SLIDE EASTWARD ACROSS THE CWA
THIS AFTN ALONG THE NORTHERN FRINGE OF BROAD UPPER-LEVEL RIDGING IN
PLACE OVER THE CENTRAL ROCKIES. WATER VAPOR SATELLITE SHOWED THIS
FEATURE OVER NORTHEAST WY AS OF 19Z MOVING QUICKLY TOWARD SOUTHWEST
SD AND THE NORTHERN PANHANDLE. CONVECTIVE CHANCES ARE THE MAIN ISSUE
IN THE NEAR TERM. ASIDE FROM MOUNTAIN CONVECTION...SHOWER AND TSTM
CHANCES WILL BE ASSOCIATED WITH LARGER SCALE FORCING IN ADVANCE OF
THE AFOREMENTIONED WAVE. THE NAM IS STILL THE MOST BULLISH WITH QPF
OVER OUR NORTHEAST ZONES WHILE THE HRRR COMPOSITE REFLECTIVITY SHOWS
FAIRLY MODEST CONVECTIVE COVERAGE. CONFIDENCE IS FAIRLY LOW IN JUST
HOW WIDESPREAD THINGS WILL BE TODAY GIVEN WEAK SUBSIDENCE BENEATH
THE RIDGE...AND RECENT RADAR ECHOS HAVE NOT BEEN ANYTHING TO WRITE
HOME ABOUT. BELIEVE WE WILL SEE SOME MID AFTN TSTM ACTIVITY THOUGH
OVER THE HIGH PLAINS. CURRENT SPEED OF THE TROUGH AXIS SUGGESTS THE
BEST FORCING FOR ASCENT AND MOISTURE WILL SHIFT EAST OF THE CWA BY
ABOUT 22Z...AFTER WHICH TIME TSTMS SHOULD DIMINISH. DESPITE GOOD SFC
HEATING TODAY...LATEST SPC MESOSCALE ANALYSIS INDICATES LESS THAN
1000 J/KG OF SBCAPE. LLVL FLOW OUT OF THE NORTH OR NORTHWEST IS NOT
CONTRIBUTING TO ANY REASONABLE SHEAR PROFILES EITHER SO ANY STRONGER
STORMS SHOULD NOT BE WIDESPREAD THOUGH THEY ARE POSSIBLE. IT SHOULD
BE A QUIET OVERNIGHT WITH AS SUBSIDENCE INCREASES OVER THE CWA. DO
NOT EXPECT FOG DEVELOPMENT TONIGHT WITH UNFAVORABLE LLVL WINDS...BUT
CANNOT RULE IT OUT IN THE PLATTE RIVER VALLEY IF WINDS ARE MORE
SOUTHEAST THAN CURRENTLY PROGGED.
SAT STILL LOOKS TO BE THE WARMEST DAY OF THE PERIOD WITH A VIGOROUS
UPPER-LEVEL TROUGH LURKING OVER THE PACIFIC NW. THERMAL RIDGE AXIS
BUILDS INTO THE CWA WITH NAM H7 TEMPS INCREASING TO 13-14 C FROM THE
LARAMIE RANGE EASTWARD. MOST MOS GUIDANCE SUGGESTS HIGHS IN THE 83
TO 93 DEGREE RANGE OVER THE PLAINS...AND THIS LOOKS REASONABLE GIVEN
THE SYNOPTIC SETUP. THE PROGRESSION OF THE TROUGH AND ASSOCIATED SFC
COLD FRONT APPEARS A BIT SLOWER THAN EARLIER MODELS SUGGESTED...SO
THIS SHOULD DELAY PCPN CHANCES UNTIL MID TO LATE AFTN ON SAT. MIDLVL
QG FIELDS SHOW GOOD ASCENT SPREADING FROM WEST TO EAST AFTER 21Z ON
SAT. THIS OCCURS ALONG WITH LLVL CONVERGENCE ASSOCIATED WITH A
STRONG SFC COLD FRONT MOVING ACROSS THE CWA...SO AM CONFIDENT IN AT
LEAST SCATTERED COVERAGE OF SHOWERS AND TSTMS. INSTABILITY COULD BE
WANING BY THE TIME CONVECTION MOVES FAR ENOUGH EAST...BUT CAN NOT
RULE OUT A STRONG OR LOCALLY SEVERE STORM WITH NAM CAPES AROUND 1500
J/KG BENEATH STEEP MIDLVL LAPSE RATES AND ABOUT 30 KTS OF H5 FLOW.
IT WILL BE BREEZY ON SAT AFTN AND EARLY EVE...ESPECIALLY ALONG AND
WEST OF THE LARAMIE RANGE AS HEIGHT GRADIENTS INCREASE ALOFT AND A
STRONG SFC LOW MOVES ACROSS NORTHERN WY. WSW H7 WINDS AROUND 35 TO
40 KTS SUGGEST STRONGER WINDS OVER THE WIND PRONE AREAS...SO BUMPED
UP GUSTS TO AROUND 45 MPH AT ARL AND BRX.
SHOWERS WILL INCREASE OVERNIGHT THROUGH SUN AM...AND COULD CONTINUE
THROUGH MUCH OF THE AFTN WITH COLDER AIR ALOFT AS THE TROUGH MOVES
OVERHEAD. THE MODELS SHOW H7 TEMPS PLUNGING INTO THE MID SINGLE
DIGITS C ON SUN IN THE POST-FROPA AIR MASS. LOOKING FOR HIGHS TO BE
SOME 10 TO 15 DEGREES COOLER THAN SAT. FLOW ALOFT BRIEFLY BECOMES
MORE ZONAL BY LATE SUN NIGHT...WITH THE ECMWF FINALLY STARTING TO
BACK OFF ON QPF BY ABOUT 06Z MON.
.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 150 PM MDT FRI AUG 29 2014
SHORTWAVE TROUGH DRIVEN BY A 100+KT JET STREAK WILL SWEEP ACROSS
THE CWFA ON MONDAY. A QUICK SHOT OF MOISTURE ALONG WITH A WEAK
COLD FRONT WILL PRODUCE PERHAPS SOME AM SHOWER ACTIVITY ACROSS
CARBON AND CONVERSE COUNTIES. BETTER CONVECTIVE CHANCES WILL AWAIT
MONDAY AFTERNOON AS WEAK INSTABILITY IS REALIZED. PROGD SBCAPES
OF AROUND 500 J/KG SUGGEST THAT MOST OF THE CONVECTION WILL BE OF
THE WEAK VARIETY. HOWEVER WITH A STRONG JET OVERHEAD RESULTING IN
AROUND 50 KNOTS OF DEEP LAYER SHEAR...CANT ENTIRELY RULE OUT A FEW
STORMS BECOMING STRONG...ESPECIALLY OVR THE WRN NEBRASKA PANHANDLE
LATE IN THE AFTERNOON. CONVECTIVE CHANCES WILL COME TO AN END
QUICKLY MONDAY EVENING. A DRY ZONAL PATTERN WILL ENSUE ACROSS THE
INTERMOUNTAIN WEST BEHIND MONDAYS DEPARTING SHORTWAVE TROF. THIS
WILL BRING A DRY AND UNSEASONABLY WARM PERIOD INTO THE REGION. H7
TEMPERATURE PROGS INCREASE TO 14-16C...WHICH WILL YIELD DAILY HIGH
TEMPERATURES THAT WILL REACH THE 80S AND LOW 90S EAST OF THE
LARAMIE RANGE...WITH 70S OVR CARBON/ALBANY COUNTIES. THESE ABOVE
AVERAGE TEMPERATURES WILL COMBINE WITH BREEZY CONDITIONS AND AN
ALREADY DRY AIR MASS TO HEIGHTEN FIRE WEATHER CONCERNS WEDNESDAY
AND THURSDAY. LATEST MODEL GUIDANCE CONTINUES TO POINT TO EITHER
DEVELOPING ACROSS ACROSS THE PACNW OR PERHAPS A CUT-OFF JUST OFF
THE CALIFORNIA COAST LATE IN THE WEEK. IN EITHER CASE...SOUTHWEST
FLOW INTO THE ROCKYS WILL PROVIDE A FAVORABLE TRAJECTORY FOR
MOISTURE TO RETURN TO THE CWFA AS EARLY AS THURSDAY NIGHT...BUT
MORE SO FOR FRIDAY. TEMPERATURES WILL ALSO BE A TAD COOLER FRIDAY
AS A THICKER CLOUD CANOPY PREVENTS FULL INSOLATION.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY AFTERNOON)
ISSUED AT 435 PM MDT FRI AUG 29 2014
CONVECTION REALLY DECREASING LATE THIS AFTERNOON AS THE UPPER
SHORTWAVE MOVES OFF TO THE SOUTHEAST. ONLY AIRPORT THAT MAY SEE
SOMETHING LATE TODAY WOULD BE KLAR. CONVECTION RETURNS SATURDAY
AFTERNOON WITH MOST AIRPORTS SEEING SOME THUNDER BY MID TO LATE
AFTERNOON.
&&
.FIRE WEATHER...
ISSUED AT 150 PM MDT FRI AUG 29 2014
NO CONCERNS FOR CRITICAL FIRE WEATHER IN THE NEAR FUTURE. A STRONG
WEATHER DISTURBANCE AND ASSOCIATED COLD FRONT WILL SWEEP ACROSS THE
AREA ON SAT AFTN THROUGH SUN MORNING. SHOWERS AND TSTMS WILL DEVELOP
FROM WEST TO EAST ACROSS SOUTHEAST WY AND THE WESTERN NE PANHANDLE
DURING THAT TIME. GUSTY WEST-TO-SOUTHWEST WINDS WILL OCCUR ALONG AND
WEST OF THE LARAMIE RANGE ON SAT WITH GUSTS OF 35 TO 45 MPH...BUT
MINIMUM RH VALUES SHOULD REMAIN ABOVE 20 PERCENT. COOLER ON SUN WITH
CONTINUED BREEZY CONDITIONS AND ISOLATED TO SCATTERED SHOWERS AND
WEAK TSTMS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...RUBIN
SHORT TERM...HAMMER
LONG TERM...HAHN
AVIATION...CLAYCOMB
FIRE WEATHER...HAMMER
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
601 PM MDT FRI AUG 29 2014
.UPDATE...
ISSUED AT 600 PM MDT FRI AUG 29 2014
GRIDDED FORECASTS UPDATED TO MODIFY THE EVENING POPS WITH ISOLATED
THUNDERSTORMS FROM SARATOGA TO CHEYENNE...THEN DRY AFTER 9 PM.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 150 PM MDT FRI AUG 29 2014
A WELL-DEFINED SHORTWAVE CONTINUES TO SLIDE EASTWARD ACROSS THE CWA
THIS AFTN ALONG THE NORTHERN FRINGE OF BROAD UPPER-LEVEL RIDGING IN
PLACE OVER THE CENTRAL ROCKIES. WATER VAPOR SATELLITE SHOWED THIS
FEATURE OVER NORTHEAST WY AS OF 19Z MOVING QUICKLY TOWARD SOUTHWEST
SD AND THE NORTHERN PANHANDLE. CONVECTIVE CHANCES ARE THE MAIN ISSUE
IN THE NEAR TERM. ASIDE FROM MOUNTAIN CONVECTION...SHOWER AND TSTM
CHANCES WILL BE ASSOCIATED WITH LARGER SCALE FORCING IN ADVANCE OF
THE AFOREMENTIONED WAVE. THE NAM IS STILL THE MOST BULLISH WITH QPF
OVER OUR NORTHEAST ZONES WHILE THE HRRR COMPOSITE REFLECTIVITY SHOWS
FAIRLY MODEST CONVECTIVE COVERAGE. CONFIDENCE IS FAIRLY LOW IN JUST
HOW WIDESPREAD THINGS WILL BE TODAY GIVEN WEAK SUBSIDENCE BENEATH
THE RIDGE...AND RECENT RADAR ECHOS HAVE NOT BEEN ANYTHING TO WRITE
HOME ABOUT. BELIEVE WE WILL SEE SOME MID AFTN TSTM ACTIVITY THOUGH
OVER THE HIGH PLAINS. CURRENT SPEED OF THE TROUGH AXIS SUGGESTS THE
BEST FORCING FOR ASCENT AND MOISTURE WILL SHIFT EAST OF THE CWA BY
ABOUT 22Z...AFTER WHICH TIME TSTMS SHOULD DIMINISH. DESPITE GOOD SFC
HEATING TODAY...LATEST SPC MESOSCALE ANALYSIS INDICATES LESS THAN
1000 J/KG OF SBCAPE. LLVL FLOW OUT OF THE NORTH OR NORTHWEST IS NOT
CONTRIBUTING TO ANY REASONABLE SHEAR PROFILES EITHER SO ANY STRONGER
STORMS SHOULD NOT BE WIDESPREAD THOUGH THEY ARE POSSIBLE. IT SHOULD
BE A QUIET OVERNIGHT WITH AS SUBSIDENCE INCREASES OVER THE CWA. DO
NOT EXPECT FOG DEVELOPMENT TONIGHT WITH UNFAVORABLE LLVL WINDS...BUT
CANNOT RULE IT OUT IN THE PLATTE RIVER VALLEY IF WINDS ARE MORE
SOUTHEAST THAN CURRENTLY PROGGED.
SAT STILL LOOKS TO BE THE WARMEST DAY OF THE PERIOD WITH A VIGOROUS
UPPER-LEVEL TROUGH LURKING OVER THE PACIFIC NW. THERMAL RIDGE AXIS
BUILDS INTO THE CWA WITH NAM H7 TEMPS INCREASING TO 13-14 C FROM THE
LARAMIE RANGE EASTWARD. MOST MOS GUIDANCE SUGGESTS HIGHS IN THE 83
TO 93 DEGREE RANGE OVER THE PLAINS...AND THIS LOOKS REASONABLE GIVEN
THE SYNOPTIC SETUP. THE PROGRESSION OF THE TROUGH AND ASSOCIATED SFC
COLD FRONT APPEARS A BIT SLOWER THAN EARLIER MODELS SUGGESTED...SO
THIS SHOULD DELAY PCPN CHANCES UNTIL MID TO LATE AFTN ON SAT. MIDLVL
QG FIELDS SHOW GOOD ASCENT SPREADING FROM WEST TO EAST AFTER 21Z ON
SAT. THIS OCCURS ALONG WITH LLVL CONVERGENCE ASSOCIATED WITH A
STRONG SFC COLD FRONT MOVING ACROSS THE CWA...SO AM CONFIDENT IN AT
LEAST SCATTERED COVERAGE OF SHOWERS AND TSTMS. INSTABILITY COULD BE
WANING BY THE TIME CONVECTION MOVES FAR ENOUGH EAST...BUT CAN NOT
RULE OUT A STRONG OR LOCALLY SEVERE STORM WITH NAM CAPES AROUND 1500
J/KG BENEATH STEEP MIDLVL LAPSE RATES AND ABOUT 30 KTS OF H5 FLOW.
IT WILL BE BREEZY ON SAT AFTN AND EARLY EVE...ESPECIALLY ALONG AND
WEST OF THE LARAMIE RANGE AS HEIGHT GRADIENTS INCREASE ALOFT AND A
STRONG SFC LOW MOVES ACROSS NORTHERN WY. WSW H7 WINDS AROUND 35 TO
40 KTS SUGGEST STRONGER WINDS OVER THE WIND PRONE AREAS...SO BUMPED
UP GUSTS TO AROUND 45 MPH AT ARL AND BRX.
SHOWERS WILL INCREASE OVERNIGHT THROUGH SUN AM...AND COULD CONTINUE
THROUGH MUCH OF THE AFTN WITH COLDER AIR ALOFT AS THE TROUGH MOVES
OVERHEAD. THE MODELS SHOW H7 TEMPS PLUNGING INTO THE MID SINGLE
DIGITS C ON SUN IN THE POST-FROPA AIR MASS. LOOKING FOR HIGHS TO BE
SOME 10 TO 15 DEGREES COOLER THAN SAT. FLOW ALOFT BRIEFLY BECOMES
MORE ZONAL BY LATE SUN NIGHT...WITH THE ECMWF FINALLY STARTING TO
BACK OFF ON QPF BY ABOUT 06Z MON.
.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 150 PM MDT FRI AUG 29 2014
SHORTWAVE TROUGH DRIVEN BY A 100+KT JET STREAK WILL SWEEP ACROSS
THE CWFA ON MONDAY. A QUICK SHOT OF MOISTURE ALONG WITH A WEAK
COLD FRONT WILL PRODUCE PERHAPS SOME AM SHOWER ACTIVITY ACROSS
CARBON AND CONVERSE COUNTIES. BETTER CONVECTIVE CHANCES WILL AWAIT
MONDAY AFTERNOON AS WEAK INSTABILITY IS REALIZED. PROGD SBCAPES
OF AROUND 500 J/KG SUGGEST THAT MOST OF THE CONVECTION WILL BE OF
THE WEAK VARIETY. HOWEVER WITH A STRONG JET OVERHEAD RESULTING IN
AROUND 50 KNOTS OF DEEP LAYER SHEAR...CANT ENTIRELY RULE OUT A FEW
STORMS BECOMING STRONG...ESPECIALLY OVR THE WRN NEBRASKA PANHANDLE
LATE IN THE AFTERNOON. CONVECTIVE CHANCES WILL COME TO AN END
QUICKLY MONDAY EVENING. A DRY ZONAL PATTERN WILL ENSUE ACROSS THE
INTERMOUNTAIN WEST BEHIND MONDAYS DEPARTING SHORTWAVE TROF. THIS
WILL BRING A DRY AND UNSEASONABLY WARM PERIOD INTO THE REGION. H7
TEMPERATURE PROGS INCREASE TO 14-16C...WHICH WILL YIELD DAILY HIGH
TEMPERATURES THAT WILL REACH THE 80S AND LOW 90S EAST OF THE
LARAMIE RANGE...WITH 70S OVR CARBON/ALBANY COUNTIES. THESE ABOVE
AVERAGE TEMPERATURES WILL COMBINE WITH BREEZY CONDITIONS AND AN
ALREADY DRY AIR MASS TO HEIGHTEN FIRE WEATHER CONCERNS WEDNESDAY
AND THURSDAY. LATEST MODEL GUIDANCE CONTINUES TO POINT TO EITHER
DEVELOPING ACROSS ACROSS THE PACNW OR PERHAPS A CUT-OFF JUST OFF
THE CALIFORNIA COAST LATE IN THE WEEK. IN EITHER CASE...SOUTHWEST
FLOW INTO THE ROCKYS WILL PROVIDE A FAVORABLE TRAJECTORY FOR
MOISTURE TO RETURN TO THE CWFA AS EARLY AS THURSDAY NIGHT...BUT
MORE SO FOR FRIDAY. TEMPERATURES WILL ALSO BE A TAD COOLER FRIDAY
AS A THICKER CLOUD CANOPY PREVENTS FULL INSOLATION.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY AFTERNOON)
ISSUED AT 435 PM MDT FRI AUG 29 2014
CONVECTION REALLY DECREASING LATE THIS AFTERNOON AS THE UPPER
SHORTWAVE MOVES OFF TO THE SOUTHEAST. ONLY AIRPORT THAT MAY SEE
SOMETHING LATE TODAY WOULD BE KLAR. CONVECTION RETURNS SATURDAY
AFTERNOON WITH MOST AIRPORTS SEEING SOME THUNDER BY MID TO LATE
AFTERNOON.
&&
.FIRE WEATHER...
ISSUED AT 150 PM MDT FRI AUG 29 2014
NO CONCERNS FOR CRITICAL FIRE WEATHER IN THE NEAR FUTURE. A STRONG
WEATHER DISTURBANCE AND ASSOCIATED COLD FRONT WILL SWEEP ACROSS THE
AREA ON SAT AFTN THROUGH SUN MORNING. SHOWERS AND TSTMS WILL DEVELOP
FROM WEST TO EAST ACROSS SOUTHEAST WY AND THE WESTERN NE PANHANDLE
DURING THAT TIME. GUSTY WEST-TO-SOUTHWEST WINDS WILL OCCUR ALONG AND
WEST OF THE LARAMIE RANGE ON SAT WITH GUSTS OF 35 TO 45 MPH...BUT
MINIMUM RH VALUES SHOULD REMAIN ABOVE 20 PERCENT. COOLER ON SUN WITH
CONTINUED BREEZY CONDITIONS AND ISOLATED TO SCATTERED SHOWERS AND
WEAK TSTMS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...RUBIN
SHORT TERM...HAMMER
LONG TERM...HAHN
AVIATION...CLAYCOMB
FIRE WEATHER...HAMMER
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1146 PM CDT FRI AUG 29 2014
.SYNOPSIS...
ISSUED AT 1244 PM CDT FRI AUG 29 2014
A DEEP RICH MOISTURE PLUME CONTINUES TO FEED INTO EASTERN IOWA AND
MUCH OF THE UPPER MIDWEST. OUR CWA FELL WEST OF A FEW HEAVY RAIN
PRODUCING STORMS IN ILLINOIS EARLIER TODAY...AND UNDER A WEAK AREA
OF SUBSIDENCE THROUGH EARLY AFTERNOON. THIS HAS ALLOWED LOW LEVELS
TO HEAT UP UNINHIBITED. AS OF 1 PM...WIDESPREAD LOWER TO MID 80S ARE
FOUND OVER EASTERN IOWA AND WESTERN ILLINOIS...WITH DEWPOINTS IN THE
70 TO 73 RANGE. HIGHS TODAY SHOULD REACH THE MID TO UPPER 80S. CAPE
VALUES ESTIMATED BY SPC RAP AS OF 1 PM ARE 2000 TO 3000 OVER ALL OF
THE CWA. A VORTICITY MAXIMA IS LOCATED IN EASTERN KS...WITH A PVA
WING OF LIFT FOUND INTO CENTRAL MISSOURI. THIS IS ALREADY DEVELOPING
A LINE OF DEEP CONVECTION FROM NORTH CENTRAL TO SOUTH
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 1244 PM CDT FRI AUG 29 2014
THE VORT MAX TO THE SOUTHWEST WILL LIFT THROUGH IOWA THIS
EVENING...HELPING ORGANIZE STORMS AS THEY MOVE THROUGH THE CWA. FROM
LATE AFTERNOON THROUGH MID EVENING...THESE SHOULD IMPACT MUCH OF THE
CWA. A LACK OF SHEAR SHOULD DECREASE ANY WIDESPREAD SEVERE WEATHER
THREAT...BUT SOME ISOLATED WIND DAMAGE IS POSSIBLE THROUGH WET
MICROBURST ACTIVITY IN THE STRONGEST CELLS. OTHERWISE....THIS SHOULD
BE HEAVY RAIN PRODUCING LINE OF STORMS...WITH SOME BRIEF TRAINING
POSSIBLE. A WIDESPREAD RAIN OF 0.25 TO 0.75 IS EXPECTED...WITH
SWATHS OF 1 TO 2 INCHES. WE ARE LIKELY TO HANDLE THIS MINOR
FLOOD/URBAN RUNOFF THREAT WITH SPS PRODUCTS.
TONIGHT...STORMS SHOULD BECOME LESS NUMEROUS...AND POSSIBLY END
FULLY. HOWEVER...WITH THE PARENT VORT MOVING BY WITH AMPLE
MOISTURE...WE WILL LEAVE POPS GOING THROUGH THE NIGHT.
SATURDAY...MODELS BRING ANOTHER QUICK SHOT OF ENERGY THROUGH WHILE
MOISTURE IS DEPARTING. THIS MAY BRING SOME SHOWERS AND STORMS TO
ROUGHLY THE EAST HALF...BUT SHOULD SUBSIDENCE BECOME MORE CONFIDENT
BEHIND TONIGHTS STORMS...WE MAY BE DRY ALL DAY SATURDAY.
TEMPERATURES LOOK MILD TONIGHT...IN THE UPPER 60S...WHILE SATURDAY
SHOULD SEE A DRY AFTERNOON REBOUND TO THE UPPER 70S TO LOWER 80S.
CLOUDS WHILE THICK IN THE MORNING SHOULD BECOME SCATTERED BY MID
DAY.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 1244 PM CDT FRI AUG 29 2014
THE MAIN FORECAST CONCERN IN THE LONG TERM PERIOD IS STORM
COVERAGE/RAINFALL AMOUNTS/SEVERE POTENTIAL WITH THE ARRIVAL OF THE
NEXT SYSTEM SUNDAY NIGHT INTO MONDAY.
EARLY IN THE PERIOD...HAVE MAINTAINED DRY FORECAST FOR SATURDAY
NIGHT THROUGH SUNDAY AFTERNOON. MEDIUM RANGE MODELS HAVE CONTINUED
A GENERAL TREND OF SLOWING THE ARRIVAL OF THE NEXT FRONTAL
BOUNDARY AND UPPER LEVEL TROUGH. HAVE REDUCED AND TRIMMED POPS
BACK TO THE NORTHWEST FOR SUNDAY EVENING...AND ADDITIONAL
ADJUSTMENTS MAY BE NEEDED OVER THE NEXT COUPLE OF DAYS. THE MAIN
WINDOW OF SHOWERS/STORMS IS NOW EXPECTED LATE SUNDAY NIGHT INTO
MONDAY MORNING. THE LATER TIMING MEANS FAVORABLE SEVERE WEATHER
PARAMETERS WILL LIKELY STAY WEST OF THE FORECAST AREA...WITH THE
MOST LIKELY SCENARIO BEING A DECAYING MCS AND POSSIBLY SOME
LOCALLY HEAVY RAIN. STORMS MAY CONTINUE INTO THE AFTERNOON...AND
POSSIBLY MONDAY NIGHT DEPENDING ON HOW FAR SOUTH THE FRONT PUSHES.
LOOKING AHEAD...CONFIDENCE IN FORECAST DETAILS IS LOWER AS THE
OPERATIONAL GFS AND EURO VACILLATE BETWEEN WEAK TROUGHING AND
ZONAL FLOW ACROSS THE REGION. TIMING AND LOCATION OF THE VARIOUS
WEAK IMPULSES IS CHALLENGING AND RIGHT NOW THERE IS NO REASON TO
VARY FROM THE CONSENSUS BLEND POPS...ESSENTIALLY SLIGHT TO LOW
CHANCE IN EVERY PERIOD THROUGH FRIDAY. TEMPERATURES ARE EXPECTED
TO BE NEAR TO SLIGHT ABOVE NORMAL THROUGH THE PERIOD...WITH
AFTERNOON HIGHS GENERALLY IN THE 8OS AND LOWS IN THE 60S TO LOWER 70S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1141 PM CDT FRI AUG 29 2014
UPPER LOW TO PASS ACROSS THE REGION THE NEXT 8-12 HOURS WITH LOTS OF
CLOUDS AND AREAS OF SHOWERS AND STORMS. MOSTLY VFR CONDITIONS ALL
TERMINALS WITH BRIEF MVFR CONDITIONS NEXT 4-6 HOURS POSSIBLE IN
ANY STORMS THAT ARE HANDLED AS A TEMPO GROUP AND VICINITY WORDING
UNTIL LATE OVERNIGHT HOURS. SKIES TO BECOME FAIR BY MID TO LATE
MORNING WITH CUMULUS CLOUD BASES ABOVE 3K AGL WITH VFR CONDITIONS
THROUGH AT LEAST 31/06Z AND CLEAR SKIES BY SUNSET. LIGHT SOUTH WINDS TO
BECOME WESTERLY AT 5 TO 10 KTS SATURDAY.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...ERVIN
AVIATION...NICHOLS
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
1127 PM CDT FRI AUG 29 2014
.AVIATION UPDATE...REGARDING 06Z TAF ISSUANCE. RADAR DEPICTING A
A BAND OF LIGHT STRATOFORM RAINS FROM THE COASTAL WATERS...THROUGH
ACADIANA AND INTO CENTRAL LOUISIANA. A FEW SHOWERS AND
THUNDERSTORMS ARE NOTED OVER THE NORTHWEST GULF SOUTH OF SABINE
PASS WHERE A LOW/MID LEVEL CIRCULATION IS IN PLACE...WITH FEATURE
PROGGED TO ADVANCE SLOWLY NORTHWARD ABOUT THE PERIPHERY OF
SUBTROPICAL RIDGE.
EXPECTED INCREASING AREA COVERAGE OF CONVECTION INLAND OVER THE
NEXT FEW HOURS AS LOW LEVEL CONVERGENCE RAPIDLY BECOMES
ESTABLISHED IN CONCERT WITH A DEVELOPING LOW LEVEL JET ASSOCIATED
WITH AFOREMENTIONED FEATURE. HAVE OPTED FOR INITIAL TEMPO GROUPS
FOR CONVECTION TRANSITIONING INTO PREVAILING LATER TONIGHT.
&&
MARCOTTE
&&
.PREV DISCUSSION... /ISSUED 926 PM CDT FRI AUG 29 2014/
DISCUSSION...
MAIN SHRA/ISO TSRA AREA OVER THE GULF THIS EVENING...WITH
LIGHT/MOD SHRA SPREADING INLAND ACROSS SE TX/S LA. NOTABLE MID
LEVEL SPIN JUST OFF THE SE TX COAST...ASSOCIATED WITH THE REMNANT
MID LEVEL VORT MAX FROM THE EARLIER TSRA CLUSTER OVER THE NW GULF.
THE NAM & HRRR CONTINUES TO SIGNAL ADDITIONAL DEVELOPMENT OF
SHRA/TSRA OVER EXTREME SE TX/S LA BETWEEN 06-12Z...WITH POSSIBLE
TRAINING OF ECHOS SETTING UP TOWARDS DAYBREAK INTO THE REMAINDER
OF THE MORNING ONCE THIS REMNANT VORT MAX MOVES INLAND AND
INCREASED LIFT SETS UP FROM THE APPROACHING UPPER LEVEL TROF. WITH
THE HIGH PRECIP H20 VALUES ALREADY IN PLACE (00Z LCH SOUNDING @
2.27") WILL NOT TAKE MUCH TO GET 2-3" OF RAINFALL...WITH LOCALLY
HIGHER AMOUNTS OF 3-5" POSSIBLE BEFORE ALL SAID AND DONE BY SAT
EVENING/EARLY SUN. THIS WARRANTED THE ISSUANCE OF A FLASH FLOOD
WATCH FOR SE TX/C AND S LA. BELIEVE THE MAIN THREAT AREA FOR THE
OVERNIGHT HOURS WILL BE ALONG AND SOUTH OF I-10...WITH THIS AREA
SHIFTING NORTHWARD AFTER DAYBREAK FOR THE REMAINDER OF THE WATCH AREA.
DML
PREV DISCUSSION... /ISSUED 633 PM CDT FRI AUG 29 2014/
UPDATE...WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS NOW PRIMARILY
OVER THE NEAR COASTAL WATERS ARE EXPECTED TO MOVE INLAND AS THE
NIGHT PROGRESSES. THIS ACTIVITY IS ASSOCIATED WITH LOW
PRESSURE OVER THE NORTHWEST GULF ADVANCING NORTHWARD. INITIAL VFR
CEILINGS ARE EXPECTED TO SLIP DOWN WITHIN MVFR.
MARCOTTE
PREV DISCUSSION... /ISSUED 411 PM CDT FRI AUG 29 2014/
DISCUSSION...
SHOWERS HAVE DROPPED RAINS ACROSS A LARGE PORTION OF SE TX AND
SRN LA TODAY...GENERALLY LESS THAN 1/2 INCH MOST LOCATIONS. THIS
HAS HELP TO KEEP TEMPERATURES IN THE 80S. RAINS ARE FROM A LOW
OFF OF BRO THAT HAS BEEN DRAGGING MOISTURE NORTHWARD. THIS
PATTERN WILL CONTINUE INTO THE OVERNIGHT HOURS WITH ADDITIONAL
SHOWERS AND THUNDERSTORMS ON TAP. TEMPS WILL FALL INTO THE MID 70S
MOST LOCATIONS BUT A FEW LOCATIONS MAY SEE LOWER 70S WITH RAIN
COOLED AIR.
TOMORROW WILL SEE ANOTHER SURGE OF MOISTURE INTO THE REGION FROM
THE GULF AND RAIN CHANCES WILL INCREASE AND TEMPS ARE EXPECTED
BACK INTO THE 80S ONCE AGAIN. RAINFALL TOTALS EXPECTED AROUND ONE
TO TWO INCHES WITH ISOLATED LOCATIONS GETTING THREE TO FOUR
INCHES. THE MOISTURE AXIS WILL CONTINUE INTO SUNDAY BUT RAIN
CHANCES WILL TAPER OFF A BIT... BUT BY MONDAY HIGH PRESSURE WILL
BUILD IN FROM THE EAST AND THIS WILL BEGIN TO SHUT OFF OUR PRECIP.
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 74 85 75 89 76 / 90 90 50 40 10
KBPT 74 87 76 90 76 / 80 80 50 40 10
KAEX 73 84 72 89 73 / 70 90 50 40 10
KLFT 75 84 75 90 76 / 90 90 50 40 10
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...FLASH FLOOD WATCH THROUGH SATURDAY EVENING FOR THE FOLLOWING
ZONES: ACADIA...ALLEN...AVOYELLES...BEAUREGARD...
CALCASIEU...EAST CAMERON...EVANGELINE...IBERIA...JEFFERSON
DAVIS...LAFAYETTE...LOWER ST. MARTIN...RAPIDES...ST.
LANDRY...ST. MARY...UPPER ST. MARTIN...VERMILION...VERNON...
WEST CAMERON.
TX...FLASH FLOOD WATCH THROUGH SATURDAY EVENING FOR THE FOLLOWING
ZONES: JEFFERSON...ORANGE.
GM...SMALL CRAFT EXERCISE CAUTION UNTIL 7 AM CDT SATURDAY FOR THE
FOLLOWING ZONES: COASTAL WATERS FROM CAMERON LA TO HIGH
ISLAND TX OUT 20 NM...COASTAL WATERS FROM INTRACOASTAL CITY
TO CAMERON LA OUT 20 NM...COASTAL WATERS FROM LOWER
ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA OUT 20 NM...
WATERS FROM INTRACOASTAL CITY TO CAMERON LA FROM 20 TO 60
NM...WATERS FROM CAMERON LA TO HIGH ISLAND TX FROM 20 TO 60
NM...WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL
CITY LA FROM 20 TO 60 NM.
&&
$$
UPDATED FOR NEW AVIATION FORECAST DISCUSSION BELOW.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 322 PM CDT FRI AUG 29 2014
AT 315PM...THERE WAS AN UPPER LEVEL TROUGH AND POTENT SHORTWAVE
OVER THE CENTRAL PLAINS. THERE WAS AN ASSOCIATED SURFACE TROUGH
OVER NORTHERN MINNESOTA AND NW MANITOBA. A WARM FRONT STRETCHED
ACROSS WEST CENTRAL AND CENTRAL WISCONSIN. MUCH OF THE NORTHLAND
HAD CLOUDY SKIES...BUT THERE WAS SOME CLEARING MOVING INTO THE FAR
SE FORECAST AREA DUE TO CLEARER SKIES FARTHER SOUTH IN THE WARM
SECTOR. SHOWERS AND STORMS WERE MOVING THROUGH THE
NORTHLAND...MAINLY THE EASTERN AND SOUTHERN FORECAST AREA.
THROUGH THIS EVENING...THE UPPER LEVEL TROUGH IN THE CENTRAL
PLAINS WILL LIFT TOWARDS WISCONSIN. THE SURFACE TROUGH WILL
CONTINUE MOVING EAST THROUGH THE FORECAST AREA...AND THE WARM
FRONT IN WISCONSIN WILL CONTINUE MOVING NORTH. THE WARM SOUTHERLY
FLOW AND MOISTURE TRANSPORT AHEAD OF THE SURFACE TROUGH WILL
CONTINUE TO BRING SHOWERS AND STORMS INTO NW WISCONSIN. THE
PRECIPITABLE WATER VALUES ARE AROUND 1.8 INCHES...SO HEAVY RAIN IS
POSSIBLE WITH ANY THUNDERSTORMS...ESPECIALLY IF THE STORMS TRAIN.
THERE IS A VERY LOW RISK OF GUSTY WINDS WITH THUNDERSTORMS IN OUR
FAR SE FORECAST AREA THROUGH THIS EVENING. THE APPROACHING WARM
FRONT AND CLEARING COULD CAUSE ENOUGH HEATING TO CAUSE ENOUGH
INSTABILITY TO RESULT IN SOME STRONG STORMS.
TONIGHT...THE PCPN CHANCES WILL GENERALLY DECREASE OVERNIGHT AS
THE MOISTURE TRANSPORT SHIFTS FARTHER EAST. A SHORTWAVE IN WESTERN
NORTH DAKOTA THIS AFTERNOON COULD BRING ISOLATED SHOWERS TO THE SW
FORECAST AREA LATE TONIGHT. THE COMBINATION OF LIGHT WIND AND HIGH
MOISTURE COULD RESULT IN PATCHY FOG FOR PARTS OF THE FORECAST
AREA.
SATURDAY...HIGH PRESSURE WILL GENERALLY KEEP THE FORECAST AREA
DRY...BUT THERE COULD BE LINGERING SHOWERS IN THE FAR SE FORECAST
AREA...AS WELL AS ISOLATED SHOWERS AND STORMS DURING THE AFTERNOON
SOUTH OF HIGHWAY 2 DUE TO WEAK CONVERGENCE NEAR A TRAILING TROUGH.
THE MORNING LOOKS CLOUDY...BUT THERE WILL LIKELY BE SCATTERING
DURING THE AFTERNOON. HIGH TEMPERATURES SHOULD BE IN THE UPPER 60S
AND LOW 70S.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 322 PM CDT FRI AUG 29 2014
OVERALL PATTERN REMAINS SIMILAR IN FEATURING A PROGRESSIVE FLOW
ALOFT ACROSS THE NRN CONUS THIS PERIOD. AFTER SOME INITIAL
COLLAPSE OF MID LVL HEIGHTS EARLY IN THE PERIOD A TREND TOWARDS A
LARGE BUILDING RIDGE OCCURS FROM THE SRN ROCKIES INTO THE MID
ATLANTIC. WHILE TOO EARLY TO TELL THIS MAY PLACE PARTS OF THE
REGION WITHIN A FAVORABLE CORRIDOR OF HIGH PWS AND POTENTIAL
MCS/MCC DEVELOPMENT. THE FIRST ROUND OF PRECIPITATION WILL MOVE
ACROSS THE NORTHLAND SUNDAY INTO MONDAY. A FEW DAYS OF GENERALLY
BENIGN WX SHOULD DEVELOP FROM LATE MONDAY INTO THURSDAY. THE AREA
WILL BE INFLUENCED BY A PASSING SFC HIGH THAT MOVES FROM THE CNTRL
PLAINS INTO THE OHIO VALLEY. ALTHOUGH SOME POPS ARE CURRENTLY IN
THE FCST TUESDAY THE MOISTURE/LIFT IS LIMITED AND LATER SHIFTS MAY
BE ABLE TO REDUCE/ELIMINATE WHAT IS CURRENTLY FCST. THE NEXT
CREDIBLE CHANCE FOR ORGANIZED LIFT AND MSTR TRANSPORT WILL BE LATE
IN THE WEEK AS A FRONTAL BDRY ARRIVES FROM THE NRN PLAINS. BY THAT
TIME THE AREA OF FORCING SHOULD HAVE SIGNIFICANT PWATS TO ACT
UPON.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1230 AM CDT SAT AUG 30 2014
A SLOW MOVING LOW PRESSURE SYSTEM WILL CONTINUE TO IMPACT THE
NORTHLAND THROUGH THE NIGHT AND EVEN INTO SATURDAY. THE LOW WILL
GRADUALLY MOVE OFF AND THE EFFECTS WILL LESSEN ON SATURDAY. RAIN WILL
CONTINUE ACROSS NORTHERN WISCONSIN ALONG WITH A FEW THUNDERSTORMS.
IFR/LIFR AND MVFR WILL GIVE WAY TO VFR ON SATURDAY. FOG WILL
CONTINUE TO DEVELOP OVERNIGHT BUT WILL GRADUALLY LIFT SATURDAY
MORNING.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 54 74 61 72 / 10 40 80 40
INL 52 73 57 71 / 10 70 70 30
BRD 58 78 60 74 / 10 70 80 20
HYR 55 79 64 75 / 10 20 80 50
ASX 53 78 63 73 / 10 10 80 50
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
UPDATE...DAP
SHORT TERM...GROCHOCINSKI
LONG TERM...CANNON
AVIATION...CLC
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1206 AM CDT Sat Aug 30 2014
.DISCUSSION...
Issued at 401 PM CDT FRI AUG 29 2014
Out of the gate this afternoon...first round of convection continuing
to track east-northeast as initial shot of vorticity and pressure
advection associated with inbound upper wave slides east across the
region. Upstream behind this afternoon/s activity...skies have
cleared and weak destabilization has occurred with latest SPC
mesoanalysis suggesting anywhere between 1000-1500 J/Kg of MLCAPE
exists across eastern KS and western MO. Heading into the late
afternoon...main concern is for redeveloping convection as next piece
of shortwave energy and associated vorticity slides over the area. As
this occurs...long-lived frontal boundary which has been in place
across the central Plains in recent days should slowly slide across
the region which should also help with possible redevelopment. Fcst
models have been playing this card quite well with latest HRRR high-
res data supporting renewed convection across eastern KS this afternoon.
For now...have advertised chc pops pretty much across the western
2/3rds of the fcst area...before gradually spreading them east during
the early overnight period. In terms of severe threats...latest
mesoanalysis shows fairly weak shear aloft. This along with a DCAPE
min/trough across our region should largely prevent widespread
severe. That said though...a few strong downbursts cannot be ruled
out if convection actually does develop.
Main front to slide through the forecast area tonight as discussed
above. This should result in a gradual decrease in storm coverage
from west to east during the early morning hrs if storms do in fact
develop. Overnight lows tonight will largely reside in the middle to
upper 60s.
By all accounts...upcoming holiday weekend shaping up to be
beautiful...at least early on that is as region will reside in a post
frontal airmass both Saturday and Sunday. Despite the fropa
tonight...limited to no cooling seeing in the 850-mb temp field thus
expect high temps in the mid to upper 80s on Saturday...and
potentially into the lower to middle 90s on Sunday as warm air
advection increases ahead of next incoming wave/front.
Much more interesting weather by Sunday night/early Monday as well
advertised longwave trough continues to dig along the Front Range. As
this occurs...cyclogenesis expected across the northern Plains with
strengthening future then expected to quickly exit into the upper
Miss Vly/western Great Lakes region by early Monday. The end result
for our area will be a slowly progressing cold front which will begin
sliding south during this period...with increasing chances for rain
from Sunday night through the Tuesday time frame. Main issue seen
from this vantage point is that this feature will likely stall
somewhere across central Missouri as it begins to interact with stout
sfc ridging in place across the lwr Miss Vly and southern Plains. A
severe wx concern initially Sunday night may quickly morph into a
hydro concern as continued moisture advection resulting from a
strengthening low-level jet of 2-3 standard deviations above normal
ascends the stalled feature and cloud layer winds remain parallel to
the front. Will have to maintain vigilance with this feature as many
locations across our northwestern zones have received heavy rainfall
in recent days. If severe wx were to develop Sunday night...bulk
shear vectors orientation parallel to the incoming front will likely
support multicell type storm morphologies...with high winds winds
posing the biggest threat before concerns change over to possible
heavy rain. That said...better frontal convergence for forced ascent
will likely remain north of our fcst area which could ultimately
limit the severe threat for our region. In any event...both flooding
and possible severe pose a risk as seen this afternoon and will
maintain mention in the HWO product for now.
Beyond this...returning southerly flow will finally lift the front
north across the region with dry weather returning in its wake by
midweek. With zonal flow expected to dominate across the lower
48...temps through the conclusion of the period should remain near or
slightly above normal.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday Night)
Issued at 1206 AM CDT SAT AUG 30 2014
Thunderstorms continue to percolate around the Kansas City terminals
late tonight, but this activity is not expected to last much longer.
By the time the TAF is valid expectations are that the thunderstorms
activity will have moved to the east or dissipated. Therefore, only
issue in the TAF is the potential for MVFR to IFR fog as skies clear
in the wake of the storms. Winds this morning will be light and
variable which will likely result in at least some haze. Have kept IFR
conditions in for the KSTJ terminal. Otherwise, Light winds will
remain rather variable through the day Saturday, with speeds under `10
knots expected through the day.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
DISCUSSION...32
AVIATION...Cutter
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1020 PM MDT Fri Aug 29 2014
.DISCUSSION...
Update forthcoming. Have made some minor adjustments to the PoP
grids for the remainder of tonight. Water vapor and IR satellite
imagery clearly show upper trof position as it approaches western
Montana. Showers and isolated thunderstorms have developed out ahead
of the trof and these continue to move across southwest Montana.
This precipitation should increase in areal coverage after midnight
and begin spreading north and east as noted by the latest RUC and
HRRR analysis. Wet and unsettled morning continues to look on track.
Temperatures look reasonable.
&&
.AVIATION...
UPDATED 0420Z.
A weather disturbance and cold front will move through the area
Saturday morning. Showers will develop ahead of the cold front over
southwest and central Montana late tonight then continue into
Saturday morning as the disturbance and cold front move through.
During the afternoon expect more showers and a few thunderstorms
near and south of a KLWT to KHLN line with scattered showers north
to near U.S. route 2. As mentioned in the previous discussion expect
generally VFR conditions with the showers/thunderstorms although can
not rule out local MVFR conditions. Showers and thunderstorms are
expected to diminish Saturday evening. Blank
&&
.PREV DISCUSSION...Issued 250 PM MDT Fri Aug 29 2014
Tonight through Sunday...Isolated showers and thunderstorm will
develop in far Southwest Montana this evening then increase in
coverage overnight. Showers and storms spread into Central Montana
by Saturday morning then continue on into Eastern Montana as an
associated upper wave moves east. A reinforcing trough swings into
the state during the afternoon with additional showers and
thunderstorms developing in Southwest and Central Montana through
the afternoon; however, only isolated showers are expected over my
northwestern zones. Conditions will improve overnight as the
trough axis moves eastward leaving a cool and slightly unsettled
airmass in place over the forecast area for Sunday. mpj
Sunday Night through Friday...Relatively quiet weather conditions
expected for first half of next week. A weak, quick-moving
shortwave trof will sweep across the state on Mon. GFS and GEM
forecast models indicate little, if any, precipitation with the trof
while the ECMWF continues to indicate broad coverage of showers
mainly over the southwest counties on Mon aftn/eve. Since a
northwest flow pattern aloft (like we`ll have on Mon) usually will
generate isolated showers with even minimal moisture and
instability, have kept in a slight chance of rain showers over the
astern third of the forecast area on Mon. Weak, transient high
pressure ridging will make for dry conditions from Tues through Wed,
with slightly warmer high temperatures (low to mid 70s) as winds
aloft transition to westerly. Stronger shortwave trof is forecast
to arrive on Thurs, though model solutions still showing some marked
run-to-run differences on the shortwave`s timing and precipitation
coverage for Thurs and Fri. General model consensus is that most of
the precipitation will occur Thur eve through midday Fri, behind a
surface cold front that tracks across the region on Thurs morning.
Some locations, especially along/south of a Helena-Lewistown line
may see rainfall totals of 0.25-0.50 inch, with lighter amounts
further north. The front will also usher in a cooler Canadian
airmass and bring snow levels down to the 6500-7500 ft range over
the central mountains and the Rocky Mtn Front.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 56 73 48 69 / 20 50 10 10
CTB 53 71 46 67 / 0 20 10 10
HLN 56 73 47 70 / 40 60 20 10
BZN 49 70 44 66 / 40 70 40 10
WEY 43 61 35 57 / 40 80 50 10
DLN 51 69 45 65 / 50 70 40 10
HVR 55 76 49 73 / 0 50 10 0
LWT 53 72 48 67 / 20 60 20 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
335 AM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 335 AM CDT SAT AUG 30 2014
LOW CLOUDS TODAY AND TSTM CHANCES FOR SUNDAY/SUNDAY NIGHT (WITH
SOME SEVERE WEATHER POTENTIAL) ARE THE PRIMARY FORECAST CONCERNS.
TROUGH AXIS HAD FINALLY SHIFTED EAST OF THE AREA WITH MAIN AREA OF
PCPN EARLY THIS MORNING FROM SERN MN ACROSS ERN IA AND DOWN INTO MO.
A 70 KNOT JET MAX AT 300 MB WAS NEAR THE OR/CA BORDER AT 00Z...WHICH
WAS ASSOCIATED WITH THE NEXT UPSTREAM SHORTWAVE TROUGH. 12 HOUR
HEIGHT FALLS OF UP TO 50 METERS WERE NOTED OVER SRN BC CANADA AND
WEAKER HEIGHT FALLS EXTENDED DOWN INTO NRN CA/WRN NV. OUR AREA WILL
BE MUCH DRIER TODAY WITH SHORTWAVE RIDGING BETWEEN THE DEPARTING
SYSTEM TO OUR EAST AND THE APPROACHING SYSTEM TO OUR WEST. LOW
CLOUDS WERE OVER ERN SD AND WRN IA EARLY THIS MORNING. SOME OF THE
HIGH RESOLUTION MODELS...INCLUDING THE HRRR AND RAP SHOWED THESE
OVER THE NRN AND ERN PARTS OF THE FCST AREA THIS MORNING. WILL
GENERALLY FOLLOW THIS TREND...THEN LET THE CLOUDS BREAK UP A BIT
THIS AFTN. PREVIOUS FORECAST LOOKED GOOD AND WAS IN LINE WITH A
BLEND OF MOS...SO LOOK FOR HIGHS MAINLY AROUND 80 TO 85.
TONIGHT...CLEAR TO PARTLY CLOUDY SKIES SHOULD BE THE RULE MUCH OF
THE NIGHT WITH AN INCREASE EXPECTED OVER THE WRN PARTS OF NERN
NE LATE. MODELS ARE IN GENERAL AGREEMENT THAT THIS AREA COULD ALSO
SEE SOME TSTMS BY DAYBREAK WITH MID LEVEL MOISTURE AND LIFT. THESE
WOULD THEN LIKELY DEVELOP EWD WITH TIME THE REST OF THE DAY.
THE MAIN SHOW WILL PROBABLY WAIT UNTIL LATE AFTERNOON OR EARLY
EVENING AND BE MORE TIED TO LOW LEVEL CONVERGENCE ALONG THE
APPROACHING COLD FRONT. AGREE WITH SPC DAY 2 OTLK WHICH HAS ALL
OF OUR AREA IN A SLGT RISK. ML CAPE VALUES ARE EXPECTED TO REACH
3000 TO 4000 J/KG IN THE AFTN AND LINGER INTO THE EVENING. 0 TO
6 KM BULK SHEAR VECTORS IN COMBINATION WITH EXPECTED CAPE SHOULD
BE SUFFICIENT FOR STORM ORGANIZATION. INITIALLY DISCRETE STORMS
WILL LIKELY MERGE INTO ONE OR MORE CLUSTERS AND/OR A LINE. 21Z
SUNDAY TO 06Z MONDAY SEEMS TO BE THE MOST FAVORED TIME BASED ON
FORECAST SOUNDINGS AND OTHER CURRENT MODEL DATA. IN ADDITION TO
THE SEVERE THREAT...LOCALLY HEAVY RAIN IS PROBABLY GOING TO BE AN
ISSUE DUE TO THE RECENT ISSUES WITH SOME STREAMS/RIVERS.
STORMS COULD LINGER TOWARD 12Z MONDAY NEAR THE MO BORDER BUT THE
REST OF THE DAY SHOULD BE MAINLY DRY WITH HIGHS IN THE UPPER 70S
NORTH TO LOWER 80S SOUTH.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 335 AM CDT SAT AUG 30 2014
MODELS AGREE ON GENERAL PATTERN BUT HAVE SOME DIFFERENCES WITH
DETAILS. NORTHWEST FLOW AT 500 MB TUESDAY SHOULD BECOME MORE ZONAL
WEDNESDAY AND THEN BECOME SOUTHWEST AS A TROUGH DIGS ACROSS THE
PACIFIC NORTHWEST LATER IN THE WEEK. DID NOT FAVOR ANY ONE MODEL
IN THIS PERIOD. THE 00Z ECMWF WAS WETTER MONDAY NIGHT FOR MOST OF
THE AREA...WHILE THE GFS WAS WETTER TUESDAY NIGHT/WEDNESDAY IN
SERN NE/SWRN IA.
HIGHS SHOULD BE MOSTLY IN THE 80S WITH SOME LOWER 90S POSSIBLE
SRN ZONES THURSDAY. A SLIGHT COOL DOWN SEEMS POSSIBLE FRIDAY INTO
SATURDAY WITH A DECENT CHANCE FOR SHOWERS/THUNDERSTORMS AS ANOTHER
FRONTAL SYSTEM MOVES THROUGH THE REGION.
&&
.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1153 PM CDT FRI AUG 29 2014
WITH SHOWERS DISSIPATING OVER EASTERN NEBRASKA...ONLY SCATTERED
MID AND HIGH CLOUDS ARE EXPECTED OVERNIGHT. HOWEVER AREAS OF FOG
AND STRATUS ARE EXPECTED TO FORM AFTER 08Z AT ALL TAF SITES. CIGS
BETWEEN FL005 AND FL012 WITH VSBYS 1-2SM ARE LIKELY 08Z TO 15Z.
THEN SCATTERED CLOUDS AND LIGHT NORTHWEST WINDS ARE FORECAST FOR
THE MAJORITY OF THE PERIOD AFTER 15Z.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...MILLER
LONG TERM...MILLER
AVIATION...DERGAN
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
328 AM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT SAT AUG 30 2014
REMNANT CONVECTIVE DEBRIS WILL CONTINUE TO SLIDE SOUTHEASTWARD
ACROSS SW NEB THROUGH SUNRISE WHILE STRATUS CONTINUES TO DROP
SOUTHWARD ACROSS ERN SD. RAP LOW LEVEL RH PROGS WOULD SUGGEST THE
STRATUS WILL SAG TO NEAR THE NIOBRARA VALLEY BY 12-15Z OR SO AND THE
HRRR HAS LOW CLOUDS EVEN FURTHER SOUTH. HAVE ADJUSTED SKY COVER FOR
THAT. PREVIOUS FCST HAD MENTION OF FOG ALSO IN THE NERN ZONES AS A
RESULT OF PREVIOUS 24 HR RAINFALL AND BELIEVE THAT THIS WOULD ALSO
BE ALONG THE FRINGE OF LOWER CLOUDS WHICH IS A TYPICAL EVOLUTION
ANYWAY. SO HAVE LEFT THE MENTION OF FOG AS IT WAS...MORE PATCHY TWD
THE SWRN PORTION OF THE AREA...ALL OF WHICH SHOULD BURN OFF BY MID
MORNING. ON THE LARGER SCALE...A TRANSITORY UPPER RIDGE WILL
PROGRESS ACROSS THE AREA TODAY AS THE NRN STREAM REMAINS
ACTIVE...WITH LARGE SCALE SUBSIDENCE IN CONTROL THROUGH THE DAY.
NEXT LONG WAVE TROUGH IS DEVELOPING ACROSS THE PAC NW WITH A LEAD PV
ANOMALY MOVING QUICKLY ACROSS THE NRN ROCKIES TODAY. A LEE SIDE SFC
TROUGH WILL DEVELOP FROM WRN SD INTO THE TX PANHANDLE BY LATE
AFTERNOON AND THE RESPONSE WILL BE AN INCREASE OF SRLY WINDS AND
DEVELOPING THERMAL RIDGE ACROSS THE HIGH PLAINS. ON THE ERN EDGE OF
THE THERMAL RIDGE /WHICH WILL BE RETREATING NWD THROUGH THE DAY/
HIGHER DEW POINTS WILL EXIST. THERE IS WEAK CONVERGENCE ASSOCIATED
WITH THIS FEATURE AS IT RETREATS DURING THE DAY...BUT DEEP LAYER
LIFT DOES NOT LOOK EVIDENT. MAX TEMPS SHOULD CREEP A FEW DEGREES
HIGHER TODAY AS A RESULT OF THE DEVELOPING THERMAL RIDGE...MOST
NOTABLY IN THE SOUTHWEST AND EASTERN PANHANDLE.
ATTENTION THEN TURNS TO LOWERING HEIGHTS ACROSS THE NRN PLAINS SAT
NIGHT AND SUNDAY. LEAD PV ANOMALY /WHICH IS BEST DEFINED INITIALLY
BY 30.00Z GFS/ WILL APPROACH THE PANHANDLE BY LATE SAT
AFTERNOON...THOUGH WEAKENING AS IT MOVES INTO THE RIDGE POSITION.
CONVERGENCE ALONG THE LEE TROUGH IS WEAK INITIALLY BUT WILL LIKELY
PROVIDE ENOUGH LIFT ALONG WITH THE HIGHER TERRAIN FURTHER WEST TO
DEVELOP AT LEAST ISOLATED TSRA WHICH WILL MOVE EWD SAT EVE...THOUGH
LOW LEVELS WILL BE FAIRLY DRY AS SUGGESTED BY WRN FCST SOUNDINGS.
HIGH PLAINS NOCTURNAL LLJ DEVELOPS THROUGH SAT EVE WHICH WILL ADVECT
MID LEVEL INSTABILITY INTO THE CENTRAL PORTION OF THE STATE AND
SHOULD MAINTAIN ENOUGH DEEP LAYER LIFT TO SUPPORT ISOLATED TSRA INTO
THE WRN PORTION OF THE FCST AREA LATE EVE AND EARLY MORNING. NAM/GEM
AND GFS SUPPORT THIS THOUGH HIRES CAMS ARE NOT SO EAGER TO DEVELOP
PRECIP. GRIDS WILL INCLUDE ISOLATED TSRA MENTION...PROGRESSING
ACROSS THE AREA THROUGH SAT NIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 328 AM CDT SAT AUG 30 2014
12Z SUNDAY AND BEYOND. ZONAL UPPER LEVEL FLOW TO PREVAIL ACROSS
MUCH OF THE CONTIGUOUS 48 TO START OFF THE EXTENDED FORECAST
PERIOD...BUT THE PATTERN DOES SHIFT SLIGHTLY SOUTHWESTERLY ACROSS
THE HIGH PLAINS ON SUNDAY WITH THE APPROACH OF AN UPPER
TROPOSPHERIC NORTHERN ROCKIES SHORTWAVE. THE APPROACH OF THE
SHORTWAVE WILL ALLOW AN AREA OF SFC LOW PRESSURE AND ATTENDANT
BAROCLINIC ZONE TO MOVE EAST ACROSS THE REGION THROUGH THE DAY ON
SUNDAY...POTENTIALLY SETTING THE STAGE FOR AN ACTIVE SEVERE
WEATHER PATTERN ACROSS OUR EAST BY LATE AFTERNOON. GUIDANCE
CONTINUES TO FAVOR EAST OF A KLBF TO KANW LINE WHERE THERMAL
ADVECTION IS SHOWN AND CONVERGENCE ALONG THE BAROCLINIC ZONE WILL
BE MAXIMIZED. THE GFS...NAM...AND EC ALL SHOW CONVECTION FIRING IN
THIS AREA...SO GIVEN THE GOOD AGREEMENT OF NOT ONLY THE FINER
DETAILS BUT ALSO THE LARGER SCALE PATTERN...FELT THAT CONFIDENCE
WAS ENOUGH TO INTRODUCE LIKELY/S INTO THE FORECAST ACROSS OUR FAR
EAST /EAST OF A MAYWOOD TO NAPER LINE/...WITH SOLID CHANCE POPS
/40-50%/ FOR LOCATIONS EAST OF THE KANW TO KLBF LINE SUNDAY
AFTERNOON. THE UPPER TROPOSPHERIC FLOW REMAINS FAIRLY
PROGRESSIVE...SO STORMS SHOULD BE LARGELY REMOVED OF THE FORECAST
AREA BY 06Z MONDAY. SFC TD/S ARE PROJECTED TO REBOUND BACK INTO
THE LOWER TO MID 60S ACROSS OUR EAST AND WHEN COMBINED WITH STEEP
LOWER TO MID LEVEL LAPSE RATES WHICH PROMOTE SB POTENTIAL ENERGY
IN EXCESS OF 2500 J/KG...ROBUST UPDRAFTS ARE ANTICIPATED. DEEP
LAYER SHEAR IS SHOWN TO BE QUITE FAVORABLE FOR SEVERE
WEATHER...WITH THE MODELS PEGGING UPWARDS OF 40-50KTS 0-6KM BULK
SHEAR...LARGE HAIL WILL BE POSSIBLE. THE UPDRAFTS SHOULD QUICKLY
CONGEAL ALONG THE BAROCLINIC ZONE INTO A QUASI-LINEAR CONVECTIVE
BAND WHICH WOULD PROMOTE DAMAGING THUNDERSTORM WIND INTO THE
EVENING.
INTO EARLY NEXT WEEK...THERE REMAINS SOME DISCREPANCIES ON THE
TIMING OF THE EXITING TROUGH...MOST NOTABLY...THE EC RETAINS A PIECE
OF ENERGY WEST OF THE FORECAST AREA...BUT BRINGS IT THROUGH MONDAY
NIGHT. THE EC GENERATES LIGHT QPF ACROSS MUCH OF THE FORECAST AREA
DURING THIS TIME PERIOD. THE GFS IN COMPARISON IS DRY AND LACKS
MUCH OF THE EVIDENCE SUPPORTING THIS ADDITIONAL TROPOSPHERIC
PERTURBATION. GIVEN THE UNCERTAINTY...WENT AHEAD AND SCALED BACK
POPS MONDAY EVENING INTO EARLY TUESDAY...BUT WILL KEEP A SLIGHT
MENTION GOING.
BEYOND EARLY TUESDAY...THE CR ALLBLEND PROCEDURE PROJECTED A DRY
FORECAST THROUGH THURSDAY OF NEXT WEEK...AND THERE ARE NO ARGUMENTS
HERE AS AN OVERALL LACK OF OMEGA WOULD BE ANTICIPATED AS THE STORM
TRACK SHIFTS NORTH AND LOW AMPLITUDE RIDGING ENCOMPASSES MUCH OF THE
CONUS. LATE IN THE EXTENDED THERE MAY BE ANOTHER SHORTWAVE
IMPACTING THE CENTRAL PLAINS...HOWEVER THE MODELS SEEM TO BE BACKING
OFF THIS SOLUTION A BIT...FOCUSING THE BEST POTENTIAL WELL NORTH OF
THE CWA. WILL KEEP THE PROCEDURE UNCHANGED FOR NOW.
NOT ANTICIPATING ANY VIOLENT TEMPERATURE CHANGES THROUGH THE
EXTENDED PERIODS...BUT WITH EACH FRONTAL PASSAGE...TEMPERATURES WILL
MODERATE SOME. THE WARMEST DAY APPEARS TO COME MID-WEEK...AS HIGHS
ON WEDNESDAY ARE FORECAST TO APPROACH THE UPPER 80S TO LOWER 90S FOR
MOST LOCATIONS. OTHERWISE HIGHS IN THE 70S TO LOW TO MID 80S SHOULD
PREVAIL FOR MOST DAYS. LOWS IN THE 50S AND 60S SEEM TO BE THE NORM
OVER THE NEXT 7 DAYS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1225 AM CDT SAT AUG 30 2014
THE STORMS THAT OCCURRED FROM VTN-LBF AND EAST LEFT A MOIST COOL
NEAR SURFACE LAYER. THE COOL MOIST AIR...CLEAR SKY AND LIGHT WIND
WILL PROBABLY RESULT IN AT LEAST A FEW PATCHES OF FG/BR. THE AREA
MOST LIKELY TO HAVE MORE WIDESPREAD FOG WOULD BE ONL-BBW WHERE
SHOWERS AND THUNDERSTORMS LEFT SIGNIFICANT RAIN AMOUNTS THIS PAST
EVENING. THE RAPID REFRESH SHORT RANGE MODELS POINT TO VISIBILITY
LESS THAN 3SM ALONG AND EAST OF A VTN-ANW-BUB LINE WITH LESS THAN
1SM POSSIBLE. HOWEVER...THE SIGNIFICANT RAIN WAS ACTUALLY EAST OF
THAT LINE AND THE SHORT RANGE MODELS MAY HAVE A SLIGHT DISLOCATION
OF THAT AS INPUT AND THAT WOULD SKEW THE OUTPUT. THE TIMING OF THE
FG/BR WILL BE 10-14Z. SINCE VTN DID NOT HAVE ANY RAIN THIS PAST
EVENING...WE WILL NOT INCLUDE BR (OR FG) IN ITS TERMINAL FORECAST
AT THIS TIME. THE INFLUENCE OF WETLANDS IN THE VICINITY OF LBF
WILL ENHANCE THE PROBABILITY OF PATCHY FOG DEVELOPING AND WE WILL
INCLUDE 2SM WITH BCFG AT LBF.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JWS
LONG TERM...JACOBS
AVIATION...SPRINGER/JWS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
257 AM EDT SAT AUG 30 2014
.SYNOPSIS...A WARM FRONT WILL RETREAT NORTHEASTWARD ACROSS CENTRAL
AND EASTERN NC AND VA TODAY. HIGH PRESSURE WILL BUILD ALOFT OVER
OUR REGION INTO MID-WEEK.
&&
.NEAR TERM /TONIGHT/...
AS OF 1030 PM FRIDAY...
TWO PRIMARY FORECAST CONCERNS FOR TONIGHT INVOLVE THE DEVELOPMENT OF
LOW STRATUS AND FOG...AND SHOWERS.
THE FORMER HAS A HIGHER PROBABILITY OF OCCURRENCE OWING TO A REGIME
OF ABUNDANT LOW LEVEL MOISTURE - CHARACTERIZED BY SFC DEWPOINTS IN
THE UPPER 60S TO MIDDLE 70S - THAT HAS POOLED INVOF THE FRONT
STALLED OVER SE NC...AND WHICH HAS SINCE BECOME TRAPPED IN THE
VERTICAL BY A SHALLOW INVERSION. LIGHT TO CALM SFC WIND AND
ASSOCIATED COOLING OF THE BOUNDARY LAYER...IN BETWEEN PERCOLATING
PATCHES OF 2-6 THOUSAND FT CLOUDINESS...SHOULD THEN SUPPORT THE
DEVELOPMENT AND EXPANSION OF LOW CLOUDS AND FOG. THE HRRR SUGGESTS
SOME FOG MAY BECOME DENSE IN PATCHES OVER THE SOUTHERN AND WESTERN
PIEDMONT...WHERE SFC WINDS HAVE BEEN...AND WILL CONTINUE TO
BE...RELATIVELY LIGHTER.
THE PROBABILITY OF SHOWERS IS LESS CERTAIN. THERE IS A QPF SIGNAL
FOR SHOWER DEVELOPMENT OVER THE NORTHERN PIEDMONT PER NEAR TERM
GUIDANCE FROM BOTH THE HRRR AND RUC...BUT FORCING FOR ASCENT AND
INSTABILITY TO DRIVE SUCH DEVELOPMENT...ARE EXPECTED TO BE VERY
WEAK. THE FORCING FOR ASCENT WILL COME COURTESY OF WEAK AND SHALLOW
ISENTROPIC UPGLIDE ATOP THE AFOREMENTIONED STALLED SFC FRONT
TONIGHT...AND RECENT REGIONAL VWP WINDS CORROBORATE THIS IDEA WITH
THEIR DEPICTION OF WEAK BUT VEERING WINDS IN THE LOWEST SEVERAL
THOUSAND FT. WILL INTRODUCE JUST A SLIGHT CHANCE OF A SHOWER
GENERALLY NORTH OF HIGHWAY 64 TO ACCOUNT FOR THIS POSSIBILITY.
LOWS GENERALLY 69 TO 75.
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 250 PM FRIDAY...
CENTRAL NC WILL REMAIN UNDER THE INFLUENCE OF AN UPPER LEVEL RIDGE
ON SATURDAY. THE LINGERING BACKDOOR FRONT IS EXPECTED TO WASH OUT
DURING THE DAY AS THE SURFACE HIGH SHIFTS OFFSHORE AND A LIGHT
SOUTHERLY RETURN FLOW DEVELOPS ACROSS THE REGION. ALL OF THIS WILL
RESULT IN A TYPICAL SUMMERTIME PATTERN...WITH HIGHS RISING INTO THE
LOWER 90S. WITH MARGINAL INSTABILITY EXPECTED TO DEVELOP (HIGHEST
ACROSS THE SOUTHEAST)...ISOLATED DIURNAL CONVECTION WILL BE
POSSIBLE...ALTHOUGH MANY AREA LIKELY REMAINING DRY. OVERNIGHT LOWS
ARE EXPECTED TO BE IN THE UPPER 60S TO LOWER 70S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
AS OF 257 AM SATURDAY...
UPPER RIDGING WILL PREVAIL FOR WHAT APPEARS TO BE THE FIRST REAL
"EXTENDED" TIME THIS SUMMER OVER NC. THEREFORE... ANY SURFACE FRONTS
APPROACHING FROM THE NORTH WILL HAVE A DIFFICULT TIME PUSHING THIS
FAR SOUTH... LIKELY STALLING OVER VA OR NEAR THE VA/NC BORDER. WE
WILL MAINTAIN A FORECAST THAT DEPICTS SLIGHTLY ABOVE CLIMATOLOGY FOR
HIGHS/LOWS... AND VERY NEAR CLIMATOLOGY FOR PM THUNDERSTORM CHANCES
(THE ONLY CHANCE OF RAINFALL IN THIS PATTERN) DURING SUMMER. EXPECT
DAILY HIGHS GENERALLY 88-94 NW TO SANDHILLS WITH LOWS 68-73. THESE
NUMBERS WILL BE 2-4 DEGREES ABOVE NORMAL. A DAILY CHANCE OF
CONVECTION IN THE AFTERNOON AND EARLY EVENING SHOULD BE LOWEST TUE
(15-20 PERCENT)... THEN PICK UP SLIGHTLY WED-FRI (30-40) PERCENT.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 819 PM FRIDAY...
CONDITIONS HAVE IMPROVED TO VFR AT ALL TERMINALS THIS EVENING. IFR
CONDITIONS WILL RETURN TO THE AREA OVERNIGHT... AS A FRONTAL
BOUNDARY REMAINS ACROSS THE AREA... WITH HIGH LOW LEVEL MOISTURE AND
LIGHT WIND. CONDITIONS WILL IMPROVE AFTER SUNRISE... AND RETURN TO
VFR DURING THE DAY SATURDAY AS THE BOUNDARY DISSIPATES.
OUTLOOK...A SUMMERTIME PATTERN WILL PERSIST THROUGH EARLY/MID NEXT
WEEK...WITH ISOLATED TO SCATTERED AFTERNOON/EVENING CONVECTION AND A
POTENTIAL FOR EARLY MORNING FOG/STRATUS.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MWS/PWB
NEAR TERM...MWS
SHORT TERM...KRD
LONG TERM...PWB
AVIATION...SEC/KRD
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1144 PM CDT FRI AUG 29 2014
.UPDATE...
ISSUED AT 1140 PM CDT FRI AUG 29 2014
NO ADDITIONAL CHANGES NEEDED FROM PREVIOUS UPDATE.
UPDATE ISSUED AT 1008 PM CDT FRI AUG 29 2014
NOT UNEXPECTED...BUT CLEARING HAS SLOWED A BIT JUST A TAD SLOWER
THAN EARLIER RAP MODEL INDICATED. THUS BACKED OFF A LITTLE IN THE
GRIDS WITH TIMING. AVIATION TAFS APPEAR OK. DID ADD PATCHY FOG TO
DVL REGION AS GOOD RADIATIONAL COOLING WILL OCCUR THERE.
SURROUNDING OFFICES HAVE FOG MENTIONED AND DONT SEE ENOUGH OF AN
IN ISSUE AS CLEARING WILL ONLY SLOWLY PROGRESS SOUTH OVERNIGHT.
TEMPS OK. RADAR SHOWS A FEW SPRINKLES LEFTOVER AROUND BEMIDJI-
FOSSTON SO KEPT ISOLD -RW TIL 05Z IN THAT AREA.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 255 PM CDT FRI AUG 29 2014
CURRENT METARS SHOW THE SFC BNDRY MOVING ACROSS ND TODAY IS
LOCATED ROUGHLY OVER THE RED RIVER VALLY FROM HCO (MN) TO FAR.
SAT CONTINUING TO SHOW SKIES OVER THE UPPER SHEYENNE BASIN AND
JAMES VALLEY REGION BREAK UP. CURRENT RADAR SHOWS A SMALL CLUSTER
OF RAIN SHOWERS/VIRGA OVER CENTRAL ND. IMMEDIATE SHORT TERM MODELS
APPEAR TO BE OVERDOING PRECIP...SO WILL GO MOSTLY WITH
CONTINUITY/WX TRENDS VS ANY MODEL CHOICE. LATER IN THE PERIOD A
FRONT MOVES INTO WRN ND...WITH GFS FASTER THAN THE ECMWF ON
TIMING. WILL USE A FCST BLEND FOR THIS PD.
THIS AFTN AND TONIGHT....SFC BNDRY NOW EAST OF AREA OF CLEARING
AND MOVING INTO MN...WHERE SKIES HAVE BEEN CLOUDY ALL DAY AND
REGION HAS NOT HEATED OUT. OVERALL NOT AN IMPRESSIVE SITUATION AND
WILL KEEP IN THE LOW CHANCE POPS WITH RAIN SHOWERS AND ISOLD TSTMS
THE MAIN THREAT. COOLEST AREAS TONIGHT WILL BE ACROSS EASTERN ND
AND INTO FAR NWRN MN WHERE SKIES WILL LIKELY CLEAR AND TEMPS COULD
DROP INTO UPPER 40S ACROSS THIS REGION.
TOMORROW AND TOMORROW NIGHT...SHORT WAVE RIDGE ALOFT WILL BRING DRY
WEATHER TO THE REGION...HOWEVER A STRONG UPPER WAVE OVER PAC NW
WILL MOVE INTO MT WHILE LOW PRESSURE DEVELOPS OVER THE PLAINS. AN
OPEN GULF WILL ALLOW STRONG H850 MOISTURE FLUX INTO THE REGION BY
SATURDAY NIGHT. EXPECT SOME ELEVATED CONVECTION TO PICK UP BY LATE
SAT EVENING AND INCREASE AFT MIDNIGHT. HAVE LIKELY POPS INTO THE
WRN ZONES AFT 06Z...HOWEVER MAIN SHOW WILL BE DRG THE DAY SUNDAY
(SEE LONG RANGE DISCUSSION) AS SFC FRONT MOVES ACROSS DAKOTAS AND
INTO MN.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 255 PM CDT FRI AUG 29 2014
SUN AND SUN NIGHT...MODELS INDICATING EXTENDED AREA OF SFC
TROUGHING/FRONT FROM EASTERN DAKOTAS DOWN THROUGH SD/NE AND INTO
NW KS. SHORT WAVE PROGGED TO BE ENTERING WRN DAKOTAS FROM EASTERN
MT AT 12Z SUNDAY. GFS IS FASTER WITH THE UPPER WAVE ENTERING THE
DAKOTAS THAN IS THE ECMWF...AND ITS TIMING WILL BE CRITICAL ON SVR
POTENTIAL FOR SUN AFTN. GULF MOISTURE SHOULD BE READILY AVAILABLE
WITH BOTH MODELS SHOWING STRONG H850 MOISTURE FLUX INTO THE
CENTRAL AND EASTERN DAKOTAS SAT NIGHT COUPLED WITH 35 TO 45 KTS OF
0-6 KM BULK SHEAR. ASSOCIATED SFC FRONT PROGGED TO ENTER THE
EASTERN DAKOTAS (WESTERN CWA) LATE SUN MORNING AND MOVE ACROSS THE
VALLEY IN THE EARLY AFTN HOURS...EXTENDING ACROSS NW AND W CNTRL
MN BY MID AFTN. BULK SHEAR BY SUN AFTN EXPECTED TO INCREASE TO 40
KTS TO 50 KTS. WITH THESE INGREDIENTS IN PLACE...THERE IS
CERTAINLY A POTENTIAL FOR SVR ACROSS MINNESOTA ON SUN AFTN. SPC
HAS ISSUED A SLIGHT RISK FOR DAY 3. CONVECTION SHOULD BEGIN
TAPERING OFF BY MIDNIGHT SUN NIGHT AND MONDAY WILL BE DRY ACROSS
MAJORITY OF THE AREA.
FOR MON NIGHT THROUGH FRIDAY...THE PERIOD SHOULD START OUT MAINLY
DRY. THE CHANCES FOR SHOWERS AND SOME STORMS COULD INCREASE BY THE
MIDDLE TO END OF NEXT WEEK...WITH MORE CYCLONIC FLOW ALOFT
TRANSITIONING TO POTENTIAL SW FLOW ALOFT. THE EXACT TIMING OF
SHORTWAVES IS TOUGH...BUT WILL LEAVE IN MENTION OF MAINLY CHANCE
TYPE POPS FOR THE END OF NEXT WEEK...WITH THE DEEPER MOISTURE AND
SOME INSTABILITY CONFINED MAINLY TO THE SOUTHERN 2/3 OF THE FORECAST
AREA.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1140 PM CDT FRI AUG 29 2014
INITIAL ISSUE WILL BE TIMING OF CLEARING OF THE IFR/MVFR CLOUDS AT
FARGO AND BEMIDJI TAF SITES. CLEARING MAKING ITS WAY INTO TVF/GFK
SITES ATTM AND WILL BE SCT-BKN AT TIMES 06Z-10Z PERIOD. WENT A BIT
MORE PESSIMISTIC AT FARGO-BEMIDJI AND KEPT IN MVFR CIGS AT FARGO
TIL JUST PAST DAYBREAK AND KEPT IFR AT BEMIDJI TIL PAST DAYBREAK
AS WELL AS COOL NORTH WINDS MOVE INTO THE MOIST AIRMASS AND MAIN
DRYING STAYS FURTHER NORTH AND WEST OF THIS REGION. OTHERWISE
LIGHT NORTH WINDS BECOMING SOUTHEAST SATURDAY AFTN-EVE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...RIDDLE
SHORT TERM...SPEICHER
LONG TERM...DK/SPEICHER
AVIATION...RIDDLE
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
403 AM EDT SAT AUG 30 2014
.SYNOPSIS...
LOW PRESSURE WILL MOVE ACROSS THE NORTHERN GREAT LAKES THIS
WEEKEND AND A COLD FRONT WILL MOVE TOWARD LAKE ERIE BUT THEN
BECOME STATIONARY ON SUNDAY. ANOTHER LOW WILL MOVE ACROSS THE LAKES
REGION MONDAY NIGHT AND A COLD FRONT WILL MOVE ACROSS THE AREA ON
TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A SHOWER THAT MOVED ACROSS THE WESTERN PORTION OF THE FORECAST
AREA DURING THE EARLY MORNING WAS OVER THE LAKE AND CONTINUING TO
MOVE NORTHEAST. THE MORNING SHOULD BE DRY AS WE WAIT FOR A THREAT
OF SHOWERS AND THUNDERSTORMS TO DEVELOP AHEAD OF THE COLD FRONT
OVER NW OH AND POSSIBLY OVER NW PA AS SOME MOISTURE MOVES UP
THROUGH WESTERN PA. THE HIGH TEMPERATURE FORECAST IS TOUGH
DEPENDING ON THE CLOUD COVER AND HOW QUICKLY ANY SHOWERS OR
THUNDERSTORMS DEVELOP. USED A BLEND OF THE GUIDANCE FOR THE
TEMPERATURE FORECAST AND USING THE REASONING THAT NE OH WILL HAVE
MORE SUNSHINE THEN NW OH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
THE WEEKEND WILL NOT BE A WASHOUT AND THE BEST CHANCE FOR RAIN
WILL BE SATURDAY NIGHT INTO SUNDAY.
THE POPS FOR TONIGHT ARE TOUGH. THE MODELS BRING IN MORE MOISTURE
OVERNIGHT AHEAD OF THE COLD FRONT THAT WILL NOT MAKE IT IN. BASED
ON THAT WENT WITH LIKELY POPS FOR THE NORTHERN PORTION OF THE
FORECAST AREA TONIGHT OR LATE TONIGHT AND THEN LIKELY OVER THE
SOUTHERN PORTION OF THE FORECAST AREA ON SUNDAY. CONDITIONS WILL
BE DRYING OUT FROM THE NORTH.
ON MONDAY THE REGION WILL BE IN A SOUTHWEST FLOW AND A WEAK
IMPULSE ALOFT IS EXPECTED TO MOVE THROUGH...THUS CONTINUED A 30 POP.
A COLD FRONT WILL BE APPROACHING THE AREA FOR MONDAY NIGHT INTO
TUESDAY. INCREASED THE POPS SOME BECAUSE OF THIS FEATURE.
AT THIS TIME SOME OF THE THUNDERSTORMS COULD BE STRONG TONIGHT
ESPECIALLY OVER EXTREME NW OH. THE PRECIPITABLE WATER VALUES GET
A LITTLE HIGH TONIGHT...SOME LOCALLY HEAVY RAIN IS POSSIBLE. MANY
AREAS HAVE DRIED OUT. HOWEVER...SOME LOCAL FLOOD ISSUES ARE
POSSIBLE. AT THIS TIME NO MENTION IN THE HAZARDOUS WEATHER OUTLOOK
BUT THAT MAY CHANGE.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
UPPER LEVEL RIDGE WILL MOVE EAST ACROSS THE AREA THROUGH THE PERIOD.
A MEDIOCRE SHORTWAVE TROUGH IS EXPECTED TO MOVE EAST ACROSS NORTHERN
AND CENTRAL CANADA BY FRIDAY BUT SHOULD REMAIN NORTH OF THE AREA.
THIS SHOULD KEEP A ZONAL FLOW PATTERN GOING THROUGH THE DURATION.
SURFACE HIGH PRESSURE OVER THE FORECAST AREA WILL MOVE EAST OF THE
REGION AND BE OFF THE ATLANTIC COAST BY FRIDAY. THIS TRANSITION WILL
BRING A RETURN SOUTHERLY FLOW INTO THE FORECAST AREA ALONG WITH MORE
STRONG WARM AIR ADVECTION. MID LEVEL AND SURFACE AIR WILL TRACK
RIGHT UP OUT OF THE PANHANDLE OF OKLAHOMA TOWARD THE END OF THE
WEEK. A COLD FRONT IS PROGGED TO MOVE EAST INTO THE AREA BY FRIDAY
EVENING AND BECOME NEARLY STATIONARY. SOME LIMITED MOISTURE
ASSOCIATED WITH THE FRONT WILL BRING WITH IT THE BEST CHANCE FOR
SHOWERS AND THUNDERSTORMS FRIDAY. SCATTERED AFTERNOON CONVECTION IS
POSSIBLE THE REST OF THE DAYS ON THE WEST SIDE OF THE HIGH PRESSURE
CENTER.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
UPPER LEVEL RIDGE STILL IN PLACE OVER THE FORECAST AREA AT THIS
TIME. A LONE SHOWER MOVED NORTH BUT REMAINED JUST EAST OF THE
TOLEDO AND FINDLAY TAF SITES. EXPECTING A POSSIBILITY FOR SHOWERS
AND THUNDERSTORMS THIS AFTERNOON OVER THE WESTERN PORTIONS OF THE
REGION. LATEST HRRR MODEL IS SHOWING A THREAT FOR AN ISOLATED
SHOWER TO MOVE NORTHEAST ALONG THE LAKE SHORE FROM CLEVELAND TO
ERIE EARLY THIS AFTERNOON. BUT WILL LEAVE THINGS DRY AT ERIE AT
THIS POINT SINCE IT WILL BE SO WIDELY SCATTERED IF IT OCCURS.
OTHERWISE DRY FOR THE REST OF THE TAF SITES. WINDS WILL BE ON THE
INCREASE LATER TONIGHT FROM THE SOUTH AS WELL. EARLIER FORECAST
MENTIONED SOME WIND SHEAR. LATEST GUIDANCE NOW SUGGESTS WINDS WILL
GRADUALLY INCREASE FROM 10 KNOTS AT THE SURFACE TO 40 KNOTS AT
2000 FEET SO NOT EXPECTING WIND SHEAR AT THIS TIME.
OUTLOOK...NON VFR LIKELY IN SHOWERS AND THUNDERSTORMS SATURDAY
THROUGH TUESDAY AT TIMES.
&&
.MARINE...
FAIRLY DESCENT FLOW WILL DEVELOP LATER TONIGHT OUT OF THE SOUTHWEST
AND COULD POSSIBLY BE STRONG ENOUGH TO SUPPORT SMALL CRAFT ADVISORY
CRITERIA FOR A PERIOD OF TIME. EXPECTING WINDS TO DIMINISH ON SUNDAY
TO LIGHT SOUTH TO SOUTHWEST AND THEN INCREASE AGAIN BY MONDAY NIGHT
AHEAD OF THE NEXT COLD FRONT. OTHERWISE...WINDS LOOK FAIRLY LIGHT
GOING INTO WEDNESDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...LOMBARDY
AVIATION...LOMBARDY
MARINE...LOMBARDY
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
128 AM EDT SAT AUG 30 2014
.SYNOPSIS...
AS THE SURFACE HIGH OVER NEW YORK MOVES EAST IT WILL ALLOW AN AREA
OF LOW PRESSURE OVER THE NORTHERN PLAINS TO MOVE INTO THE GREAT
LAKES. AS IT APPROACHES THE LOCAL AREA WE WILL SEE AN INCREASE IN
CLOUDS AND STORM ACTIVITY STARTING FROM WEST TO EAST LATE
SATURDAY. ANOTHER LOW PRESSURE SYSTEM WILL MOVE OVER THE LAKES
REGION MONDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
ADDED A THREAT OF SHOWERS TO THE WESTERN PORTION OF THE FORECAST
AREA AS PER THE RADAR. IT SHOULD DECREASE. ELSEWHERE PARTLY CLOUDY
SHOULD BE OK. MADE MINOR ADJUSTMENTS TO SOME OF THE LOWS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/...
A DISTURBANCE FROM THE WEST WILL APPROACH THE REGION ON SATURDAY.
THE BEST CHANCE FOR CONVECTION WILL BE IN THE AFTERNOON...BUT
COULD SEE SOME STRAY STORMS IN THE FAR WEST BEFORE NOON. FOCUS
FOR THE GREATEST COVERAGE WILL BE OVER THE WESTERN HALF OF THE
FORECAST AREA WHERE MOISTURE AND INSTABILITY WILL BE GREATER. THE
MODELS ARE SUGGESTING SOME MOISTURE WILL BECOME AVAILABLE IN THE
FAR EASTERN COUNTIES AS IT WRAPS AROUND THE BACKSIDE OF THE SFC
HIGH..BUT NOT CONVINCED THIS WILL BE ENOUGH WHEN COMBINED WITH A
WEAK CAP TO GENERATE STORMS FOR THE FIRST HALF OF THE DAY. THERE
IS SOME SUGGESTION THAT THERE WILL BE A DRY SLOT BETWEEN THE TWO
SYSTEMS KEEPING PLENTY OF SUNSHINE AND DRY CONDITIONS OVER THE
EASTERN 2/3RDS OF THE CWA. TEMPERATURES WILL BE ABLE TO CLIMB INTO
THE MID/UPPER 80S ACROSS THE REGION...WELL ABOVE THE UPPER 70
NORMALS FOR THIS TIME OF YEAR. THIS COMBINED WITH HIGH DEW POINTS
WILL MAKE HEAT INDEX VALUES IN THE UPPER 80S TO NEAR 90. THE JET
DYNAMICS BECOME FAVORABLE LATER IN THE AFTERNOON AND GRADUALLY
IMPROVES EAST INTO THE EVENING HOURS WITH INCREASED FORCING AND
PLENTIFUL MOISTURE. WITH THE UPPER TROUGH PASSING OVER THE AREA
SUNDAY WE WILL SEE A LOWERING OF POPS FROM NW WITH REDUCED
FORCING. THE RAIN CHANCES WILL LINGER FOR THE BETTER PART OF THE
DAY OVER THE SOUTHEAST COUNTIES...WHERE THE MAIN THREAT WILL BE
THE HEAVY RAIN WITH PW VALUES AROUND 1.8". POPS SUNDAY NIGHT WILL
DROP AND THERE WILL BE A PERIOD WITHOUT STORMS THROUGH THE FIRST
HALF OF LABOR DAY. THE SECOND UPPER TROUGH WILL MOVE INTO THE AREA
FROM THE PLAINS MONDAY NIGHT. IN ADVANCE OF THIS SYSTEM WE COULD
SEE SOME SCATTERED STORMS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
JET STREAM CONTINUES TO TRACK ZONALLY ACROSS THE NORTHERN TIER
STATES TAKING A SYSTEM ACROSS THE GREAT LAKES TUESDAY. THIS FRONT
WILL MAKE LITTLE SOUTHERN PROGRESS LIKELY DISSIPATING OVER THE OHIO
VALLEY. SURFACE HIGH PRESSURE WEAKLY IN CONTROL WEDNESDAY AND
THURSDAY. ANOTHER SYSTEM WILL BE ON DECK FOR FRIDAY. OVERALL DECENT
MODEL AGREEMENT...BUT WITH THE ZONAL FLOW TIMING MAY BE OFF THIS FAR
OUT. CENTERED PRECIP CHANCES AROUND FRONTAL ZONES. TEMPERATURES WILL
RUN NEAR NORMAL.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
UPPER LEVEL RIDGE STILL IN PLACE OVER THE FORECAST AREA AT THIS
TIME. A LONE SHOWER MOVED NORTH BUT REMAINED JUST EAST OF THE
TOLEDO AND FINDLAY TAF SITES. EXPECTING A POSSIBILITY FOR SHOWERS
AND THUNDERSTORMS THIS AFTERNOON OVER THE WESTERN PORTIONS OF THE
REGION. LATEST HRRR MODEL IS SHOWING A THREAT FOR AN ISOLATED
SHOWER TO MOVE NORTHEAST ALONG THE LAKE SHORE FROM CLEVELAND TO
ERIE EARLY THIS AFTERNOON. BUT WILL LEAVE THINGS DRY AT ERIE AT
THIS POINT SINCE IT WILL BE SO WIDELY SCATTERED IF IT OCCURS.
OTHERWISE DRY FOR THE REST OF THE TAF SITES. WINDS WILL BE ON THE
INCREASE LATER TONIGHT FROM THE SOUTH AS WELL. EARLIER FORECAST
MENTIONED SOME WIND SHEAR. LATEST GUIDANCE NOW SUGGESTS WINDS WILL
GRADUALLY INCREASE FROM 10 KNOTS AT THE SURFACE TO 40 KNOTS AT
2000 FEET SO NOT EXPECTING WIND SHEAR AT THIS TIME.
OUTLOOK...NON VFR LIKELY IN SHOWERS AND THUNDERSTORMS SATURDAY
THROUGH TUESDAY AT TIMES.
&&
.MARINE...
THUNDERSTORMS AND A CHOPPY LAKE SATURDAY NIGHT/SUNDAY ARE THE MAIN
CONCERNS FOR THE MARINE FORECAST. AS HIGH PRESSURE SHIFTS EAST
TONIGHT WINDS ON THE LAKE WILL BECOME SOUTHERLY FOR SATURDAY...AND
THEN SOUTH-SOUTHWEST FOR SATURDAY NIGHT. THERE IS A LITTLE BIT OF
WIND FORECAST FOR SATURDAY NIGHT INTO SUNDAY...WITH SPEEDS OF 10 TO
20 KNOTS ON THE LAKE. THIS WILL RESULT IN A CHOPPY LAKE...WITH THE
POSSIBILITY OF NEEDING A SMALL CRAFT ADVISORY. THUNDERSTORM CHANCES
ARE FOCUSED PRIMARILY ON SATURDAY EVENING AND SATURDAY
NIGHT...CLEARING OUT ON SUNDAY. A COLD FRONT NEVER REALLY CROSSES
THE LAKE THIS WEEKEND...BUT INSTEAD WEAKENS OVERHEAD. LIGHTER
SOUTHWEST FLOW CONTINUES SUNDAY AND MONDAY. A COLD FRONT THAT SHOULD
CROSS THE LAKE ARRIVES FOR TUESDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JAMISON
NEAR TERM...KIELTYKA
SHORT TERM...JAMISON
LONG TERM...OUDEMAN
AVIATION...LOMBARDY
MARINE...OUDEMAN
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
435 AM CDT SAT AUG 30 2014
.DISCUSSION...
LATEST WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL TROUGH OVER THE
UPPER MIDWEST MOVING TOWARDS THE GREAT LAKES WITH ANOTHER TROUGH
PUSHING ACROSS THE PAC NW. TROUGH AXIS STRETCHES FROM THE MIDWEST
INTO TX WITH A WEAK SHORT WAVE TROUGH OVER S TX. WATER VAPOR
IMAGERY SHOWS DRIER AIR ON THE BACK SIDE OF THIS SHORTWAVE WITH
MOIST AIR AND ASCENT TO THE EAST OVER SE TX. SHOWERS AND
THUNDERSTORMS HAVE CONTINUED TO DEVELOP ALONG THE COAST AND IN THE
OFFSHORE WATERS OF THE NW GULF IN RESPONSE TO THE LIFT. THERE IS
STILL PLENTY OF TROPICAL MOISTURE LINGERING OVER THE AREA TO
SUPPORT HIGH RAIN RATES AND LOCALLY HEAVY RAINFALL. HIGHER RAIN
CHANCES REMAIN IN THE FORECAST ALONG THE COAST BUT NOT QUITE AS
MUCH AS BEFORE. POPS OF 60/70 PERCENT LOOK REASONABLE ESPECIALLY
SINCE THE MAIN MOISTURE AXIS HAS SHIFTED MOVER OVER SW LA AS
GFS/ECMWF HAVE BEEN SUGGESTING. EVEN HI RES WRF AND HRRR FORECASTS
SHOW MOST OF THE CONVECTION ALONG THE COAST AND ACROSS E TX INTO
SW LA. WILL KEEP 60 POPS IN THE FORECAST FOR MUCH OF THE AREA THIS
AFTERNOON AS WIDESPREAD CONVECTION COULD STILL DEVELOP WITHIN
MOIST UNSTABLE AIRMASS DUE TO DAY TIME HEATING. THERE WILL STILL
BE A DECENT GRADIENT BETWEEN HIGH RAIN CHANCES AND LOW RAIN
CHANCES. DEEP MOISTURE WILL STILL SUPPORT RAIN RATES OF EASILY 1
TO 2 INCHES OF RAIN AN HOUR. STORMS SHOULD BE MOVING AT A
REASONABLE SPEED SO ANY FLOOD THREAT WILL BE VERY LOCALIZED.
UPPER LEVEL TROUGH AXIS SHEARS OUT OVER THE AREA WITH UPPER LEVEL
RIDGING BEGINNING TO TAKE SHAPE OVER MUCH OF THE SOUTHERN U.S.
MODELS STILL KEEP DEEP MOISTURE IN PLACE WHICH COULD STILL SUPPORT
SCT THUNDERSTORM ACTIVITY DURING THE DAY SUNDAY WITH DAYTIME
HEATING. FORECAST WILL KEEP 40/50 POPS ALONG THE MAIN MOISTURE
AXIS. AGAIN LOCALLY HEAVY RAINFALL WILL BE POSSIBLE.
MON/TUE THE UPPER LEVEL RIDGE BECOMES MORE ESTABLISHED OVER TX AS
POTENT SHORTWAVE OVER PAC NW MOVES ACROSS THE N PLAINS. TROPICAL
DISTURBANCE IN W CARIBBEAN WILL MOVE TOWARDS THE YUCATAN OVER THE
WEEKEND AND INTO THE GULF MON/TUE. THE RIDGE SHOULD HELP STEER
THIS TROPICAL WAVE TOWARDS THE MEXICAN COAST TUE INTO WED. MAIN
IMPACT FOR THE TX COAST MAY BE ANOTHER INCREASE IN TROPICAL
MOISTURE. FORECAST WILL CONTINUE WITH MAINLY 20/30 POPS FOR THE
MIDDLE OF THE COMING WEEK THROUGH THE END OF THE WEEK. MAX TEMPS
WILL GRADUALLY INCREASE BACK INTO THE MID 90S FOR MOST AREAS AS
THE RIDGE INCREASES.
&&
.MARINE...
LIGHT TO MODERATE ONSHORE WINDS SHOULD WEAKEN SLIGHTLY TODAY
BEFORE PICKING UP AGAIN THIS EVENING. A SCEC MAY BE NEEDED
OVERNIGHT INTO SUNDAY MORNING AS THE PRESSURE GRADIENT TIGHTENS
ACROSS THE REGION. SCATTERED SHOWERS AND THUNDERSTORMS WILL
CONTINUE ACROSS THE COASTAL WATERS OVER THE WEEKEND AS AN UPPER
LEVEL DISTURBANCE MOVES ACROSS THE REGION. 38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 93 74 94 76 95 / 30 20 30 10 20
HOUSTON (IAH) 90 76 92 77 93 / 60 50 50 10 30
GALVESTON (GLS) 87 80 89 81 90 / 60 50 50 10 30
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...39
AVIATION/MARINE...38
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
417 AM EDT SAT AUG 30 2014
.SYNOPSIS...
A STALLED FRONT TRAILED FROM SOUTH CAROLINA TO ILLINOIS THIS
MORNING. THIS FRONT WILL MOVE NORTH AND DISSIPATE OVER THE MID
ATLANTIC REGION BY SUNDAY. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
THE GREAT LAKES TONIGHT AND SUNDAY WITH A COLD FRONT TRAILING FROM
THE UPPER MISSISSIPPI VALLEY TO THE CENTRAL PLAINS BY SUNDAY
NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 410 AM EDT SATURDAY...
RADAR SHOWED A NARROW BAND OF SHOWERS FROM ASHE COUNTY NC TO HALIFAX
COUNTY VA. HRRR MOVES THIS PRECIPITATION NORTH THEN HAS IT
DISSIPATING BY 12Z/8AM. IN CONTRAST THE 4KM NAM HAS THE
PRECIPITATION MOVING ALL THE WAY INTO CENTRAL VIRGINIA BY NOON. WILL
LEAN TOWARD THE NAM SOLUTION.
FRONT WAS STATIONARY FROM ILLINOIS TO SOUTH CAROLINA. MODELS TAKE
SURFACE HIGH PRESSURE OFF THE NEW ENGLAND COAST TODAY...ALLOWING THE
BOUNDARY TO MOVE NORTH...BUT EXPECT IT WILL TAKE MUCH OF THE DAY TO
MOVE OUT OF THE COUNTY WARNING AREA. WINDS COMING AROUND TO THE
SOUTH AND ANY CLEARING IN THE AFTERNOON WILL INFLUENCE HOW MUCH
TEMPERATURES WILL RISE TODAY. CLOUD COVER WILL ALSO LIMIT
INSTABILITY TODAY...SO EVEN WITH THE FRONT MOVING THROUGH THE
COVERAGE OF SHOWERS AND THUNDERSTORMS WILL REMAIN ISOLATED TO
SCATTERED. 00Z CANADIAN STARTS BREAKING OUT CLOUD COVER AROUND
14Z/10AM BUT DOES NOT HAVE ALL THE LOW CLOUDS ERODING UNTIL NEARLY
19Z/3PM. WILL STAY CLOSE TO THIS TIMING.
UPPER RIDGE AXIS IS JUST OFF THE SOUTHEAST COAST BY TONIGHT. BROAD
SOUTHWEST FLOW FROM THE LOWER MISSISSIPPI VALLEY TO THE EASTERN GREAT
LAKES TONIGHT. THE SHORT WAVE COMING OUT OF THE NORTHERN GULF AND
THE BEST Q-V FORCING ALONG THE APPROACHING COLD FRONT WILL STILL BE
WEST OF THE FORECAST AREA BY SUNDAY MORNING. MID AND HIGH CLOUDS
WILL COVER THE WESTERN COUNTY WARNING AREA OVERNIGHT...THEN
INCREASING PROBABILITY OF PRECIPITATION IN THE FAR WEST. WITH THE
INCREASING CLOUDS AND SINCE THE FORECAST AREA WILL BE WELL WITHIN
THE WARM SECTOR TONIGHT...NOT MUCH DROP IN TEMPERATURES IS EXPECTED.
USED THE WARMER GUIDANCE FOR OVERNIGHT LOWS.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 310 AM EDT SATURDAY...
A STUBBORN UPPER LEVEL RIDGE WILL HUG THE SOUTHEASTERN COAST LONGER
THAN PREVIOUSLY EXPECTED. FROM A MODEL STAND POINT...THIS UPPER
RIDGE IS ALSO FARTHER INLAND...WHICH WILL LOWER THE CHANCE OF
SHOWERS AND THUNDERSTORMS AS THE SHORT WAVE TRACK IS PUSHED
WESTWARD. THE LATEST 00Z MODELS TRACKS A TROPICAL SHORT WAVE ON THE
OUTER RINGS OF THE RIDGE ACROSS EASTERN TENNESSEE AND CENTRAL
KENTUCKY SUNDAY MORNING...THEN OVER THE OHIO VALLEY IN THE
AFTERNOON. AS THIS SHORT WAVE MOVES OVER THE OHIO VALLEY IN THE
AFTERNOON...MID LEVEL CAPPING WEAKENS ALLOWING STORMS TO GENERATE
ALONG OUT FLOW BOUNDARIES AND IN MODEST INSTABILITIES. WITH THE
STRONGEST LOW LEVEL JET REMAINING OVER THE TENNESSEE AND OHIO
VALLEYS...DISORGANIZED PULSE-LIKE STORMS ARE EXPECTED OVER THE
MOUNTAINS IN THE AFTERNOON AND MAY DRIFT EAST OF THE BLUE RIDGE IN
THE EVENING...IF THE RIDGE DOES JOG TO THE SOUTHEAST. THERE WILL
ALSO BE A LEE TROUGH OVER THE PIEDMONT THAT MAY HELP FIRE STORMS
EAST OF THE BLUE RIDGE DURING THE LATE AFTERNOON AND EVENING HOURS.
CAN NOT RULE OUT THE CHANCE FOR A FEW STORMS TO BECOME SEVERE WHERE
THE CAP IS THE WEAKEST...MOUNTAIN EMPIRE TO THE BLUEFIELD RICHLANDS
AREA. SINCE THE MODELS HAVE MOVED ORGANIZED CONVECTION TO THE
WEST...LOWERED POPS ESPECIALLY IN THE EAST. SINCE THE CHANCES OF
SHOWERS IS LOWER AND SCATTERED IN NATURE...INCREASE TEMPERATURES
ACROSS THE MOUNTAINS INTO THE MID 80S AND U80S-L90S EAST OF THE BLUE
RIDGE.
ON MONDAY...MODELS ONCE AGAIN DRIFT UPPER LEVEL RIDGE TO THE
SOUTH...PLACING THE OUTER RINGS ACROSS THE FORECAST AREA. A WEAK
SHORT WAVE IS EXPECTED TO TRACK ALONG THE SOUTHERN APPALACHIANS
BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS TO THE AREA MONDAY.
ONCE THIS SHORT WAVES TRACKS NORTH OF THE AREA...POSSIBLY BY EARLY
AFTERNOON...SURFACE HIGH PRESSURE WILL BUILD ACROSS THE REGION
MONDAY NIGHT. WITH THE AREA REMAINING IN A MUGGY AIR MASS...PATCHY
DENSE FOG IS LIKELY FOR MOUNTAIN VALLEYS. IF SHOWERS ARE PRIMARILY
DURING THE MORNING...MONDAY AFTERNOON TEMPERATURES WILL WARM INTO
THE MID 80S IN THE WEST TO U80S-L90S EAST OF THE BLUE RIDGE.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 330 PM FRIDAY...
FLAT UPPER RIDGE IS EXPECTED TO DOMINATE OUR MID-WEEK WEATHER
PATTERN ACROSS THE CENTRAL APPALACHIAN AND MID-ATLANTIC REGION. THIS
SHOULD MAINTAIN SUMMER-LIKE TEMPERATURES THROUGH THE ENTIRE PERIOD
WITH HIGHS NEAR 90F IN THE PIEDMONT AND MID-80S IN THE MOUNTAINS
ALONG WITH NIGHT-TIME LOWS IN THE 60S TO LOW 70S. COULD END UP BEING
ONE OF THE WARMEST WEEKS OF THE SUMMER EVEN AS THE SO-CALLED
METEOROLOGICAL SUMMER ENDS ON AUGUST 31. PRECIPITATION WILL ALSO
GENERALLY BE OF SUMMER-LIKE CHARACTER WITH DIURNALLY DRIVEN
CONVECTION PROVIDING THE BEST CHANCES FOR RAINFALL. WEDNESDAY
AFTERNOON LOOKS LIKE THE MOST PROMISING DAY FOR STORMS AS WEAK
FRONTAL BOUNDARY PUSHES ACROSS THE CWA. THURSDAY AND FRIDAY LIKELY
TO BE DRIER ALTHOUGH WIDELY SCATTERED SHOWERS STILL POSSIBLE.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AS OF 140 AM EDT FRIDAY...
BROAD AREA OF STRATUS HAD SPREAD WEST ACROSS THE REGION. THE
WESTERN EDGE WAS CLOSE TO KLWB AND KBLF. THESE AIRPORTS MAY GO
BACK AND FORTH BETWEEN SCATTERED VFR CLOUDS AND MVFR CEILINGS
THROUGH 14Z/10AM. FOR KBCB/KROA/KDAN AND KLYH HIGHER CONFIDENCE
THAT CEILINGS WILL LOWER TO MVFR OR IFR.
IMPROVEMENT IN CONDITIONS WILL BE SLOW THIS MORNING AS A FRONT
LIFTS NORTH THROUGH THE AREA. ONLY MEDIUM CONFIDENCE AS TO WHEN
CEILINGS WILL LIFT BACK TO VFR. THE THREAT OF SHOWERS AND
THUNDERSTORMS THROUGH THE TAF PERIOD REMAINS LOW ENOUGH TO KEEP
OUT OF THE FORECAST FOR NOW.
EXTENDED DISCUSSION...
ANY ISOLATED OR SCATTERED SHOWERS AND STORMS WILL BE MAINLY
ALONG AND NORTH OF A KHSP-KFVX LINE THIS EVENING...JUST SOUTH OF
THE AGAIN STALLED FRONTAL BOUNDARY.
LATE TONIGHT THROUGH SUNDAY EVENING AN AREA OF LOW PRESSURE WILL
HEAD EASTWARD THROUGH THE GREAT LAKES REGION TOWARD NEW ENGLAND.
ITS ASSOCIATED COLD FRONT WILL SWEEP THROUGH THE REGION BRINGING A
GENEROUS COVERAGE OF SHOWERS AND SOME STORMS. SUB-VFR CONDITIONS
ARE EXPECTED TO ACCOMPANY THE SYSTEM AND PRECIPITATION.
ANOTHER COLD FRONT IS EXPECTED TO PRODUCE SIMILAR CONDITIONS TUESDAY
INTO WEDNESDAY. HOWEVER...MODEL GUIDANCE FOR THIS ONE OFFERS
PRECIPITATION IN A MORE SCATTERED DISTRIBUTION. AS SUCH...THE
MAGNITUDE OF SUB-VFR CONDITIONS MAY BE LESS.
&&
.EQUIPMENT...
AS OF 730 AM EDT FRIDAY ...
THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WILL
BE OUT OF SERVICE UNTIL FURTHER NOTICE. A PART HAS BEEN BACK-ORDERED.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...RCS
LONG TERM...PC
AVIATION...AMS/JH
EQUIPMENT...AMS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
143 AM EDT SAT AUG 30 2014
.SYNOPSIS...
A STALLED FRONTAL BOUNDARY NEAR THE SOUTH CAROLINA...NORTH
CAROLINA BORDER WILL MOVE GRADUALLY NORTH TONIGHT THROUGH
SATURDAY...AND BE POSITIONED OVER NORTHERN VIRGINIA BY SATURDAY
AFTERNOON. A MORE SUBSTANTIAL COLD FRONT WILL APPROACH THE AREA
SATURDAY NIGHT AND MOVE THROUGH THE AREA SUNDAY AND SUNDAY NIGHT.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 820 PM EDT FRIDAY...
EVENING SOUNDINGS SHOW MOISTURE TRAPPED BENEATH THE INVERSION AT
85H AIDED BY SHALLOW SE FLOW NORTH OF THE RESIDUAL FRONT TO THE
SOUTH. MOST INSTABILITY THIS EVENING REMAINS OVER THE FAR SW WHERE
STILL HAVE A FEW SHOWERS ONGOING NEAR THE FRONT. THUS LEAVING IN
SOME CHANCE POPS THERE A WHILE LONGER AS THE HRRR SHOWS SOME OF
THIS COVERAGE SLIDING NORTH THROUGH MIDNIGHT. OTRW SATELLITE
DEPICTING LOW CLOUDS SPREADING BACK NORTH FROM SOUTHERN VIRGINIA
ATTM AHEAD OF THE BOUNDARY THAT WILL LIFT SLOWLY BACK NORTH
OVERNIGHT. MOST LATEST MODEL SOLUTIONS SHOW LOW CLOUDS REMAINING
ALONG/EAST OF THE BLUE RIDGE THROUGH MORNING WITH ONLY THE FAR
SOUTH AND WEST STAYING MORE PC ALONG THE PERIMETER OF THE WEAK
WEDGE. SHOWER CHANCES ELSW REMAIN IFFY GIVEN LOSS OF HEATING WITH
THE BOUNDARY ACROSS THE REGION LATE. LATEST NAM AND TO SOME DEGREE
THE HRRR WANT TO DEVELOP A FEW SHRA CLUSTERS ALONG AND JUST EAST
OF THE BLUE RIDGE AFTER MIDNIGHT...WHILE MOST OTHERS DRY OR
FARTHER SOUTH WITH ISOLATED COVERAGE. SINCE ALREADY HAVE SOME
ISOLATED POPS GOING AND SEEING SOME INSTABILITY ABOVE THE
INVERSION...WILL LEAVE IN AND EXTEND INTO SOUTHSIDE VIRGINIA
OVERNIGHT. OTRW FOG/LOW CLOUDS LOOK ON TRACK WITH JUST SOME UPWARD
ADJUSTS TO LOW TEMPS GIVEN THE CLOUD CANOPY AND MOIST DEWPOINTS
OVERNIGHT.
WE EXPECT A BREAK IN THE PRECIPITATION SATURDAY MORNING WITH THE
FORCING ASSOCIATED WITH THE FRONT NORTH OF THE REGION.
HOWEVER...BY THE AFTERNOON...ENOUGH DAYTIME HEATING IS EXPECTED TO
REFIRE SHOWERS AND PERHAPS A FEW THUNDERSTORMS IN THE NORTHERN
PARTS OF THE REGION CLOSEST TO THE NEW LOCATION OF THE STALLED
FRONT. ALSO...INCREASING SOUTHERLY WINDS WILL FOCUS UPSLOPE
ISOLATED SHOWER AND THUNDERSTORM POTENTIAL ALONG THE CREST OF THE
BLUE RIDGE.
LOW TEMPERATURES TONIGHT WILL BE A MIX OF LOW TO MID 60S ACROSS THE
MOUNTAINS WITH MID TO UPPER 60S ACROSS THE PIEDMONT. ON
SATURDAY...HIGH TEMPERATURES IN THE LOW TO MID 80S WILL BE COMMON IN
THE MOUNTAINS WITH UPPER 80S TO NEAR 90 ACROSS THE PIEDMONT.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY/...
AS OF 330 PM EDT FRIDAY...
UPPER LEVEL RIDGE FORECAST OVER THE SOUTHEASTERN CONUS TO REMAIN IN
PLACE IN THE SHORT-TERM WITH THE MAIN WEATHER FEATURE A SERIES OF
SOUTHERN STREAM SHORT-WAVES EXPECTED TO TRACK FROM THE GULF COAST
NORTHEAST INTO THE OHIO VALLEY. 12Z MODEL RUNS OF GFS/NAM/EURO
SHOWING THIS FEATURE OR SERIES OF FEATURES TRACKING SOMEWHAT
FURTHER WEST THAN PREVIOUS RUNS DUE PARTLY TO THE STRONG RIDGE.
AXIS OF HEAVIEST RAINFALL SHOULD STAY WEST OF OUR CWA BUT STILL
HAVE LIKELY POPS IN THE FAR WEST ON SUNDAY TAPERING TO CHANCE
ACROSS THE PIEDMONT ON SUNDAY. RIDGE FLATTENS SOMEWHAT ON MONDAY
AS UPPER TROUGH ENERGY REMAINS WILL NORTH BUT WILL STILL BE
CHANCES FOR MAINLY AFTERNOON SHOWERS AND SCATTERED THUNDERSTORMS
MONDAY AFTERNOON. TEMPS WILL REMAIN WARM THROUGH THE PERIOD WITH
MAINLY 80S FOR HIGHS AND 60S FOR LOWS EVEN WITH CONSIDERABLE
CLOUDS ON SUNDAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 330 PM FRIDAY...
FLAT UPPER RIDGE IS EXPECTED TO DOMINATE OUR MID-WEEK WEATHER
PATTERN ACROSS THE CENTRAL APPALACHIAN AND MID-ATLANTIC REGION. THIS
SHOULD MAINTAIN SUMMER-LIKE TEMPERATURES THROUGH THE ENTIRE PERIOD
WITH HIGHS NEAR 90F IN THE PIEDMONT AND MID-80S IN THE MOUNTAINS
ALONG WITH NIGHT-TIME LOWS IN THE 60S TO LOW 70S. COULD END UP BEING
ONE OF THE WARMEST WEEKS OF THE SUMMER EVEN AS THE SO-CALLED
METEOROLOGICAL SUMMER ENDS ON AUGUST 31. PRECIPITATION WILL ALSO
GENERALLY BE OF SUMMER-LIKE CHARACTER WITH DIURNALLY DRIVEN
CONVECTION PROVIDING THE BEST CHANCES FOR RAINFALL. WEDNESDAY
AFTERNOON LOOKS LIKE THE MOST PROMISING DAY FOR STORMS AS WEAK
FRONTAL BOUNDARY PUSHES ACROSS THE CWA. THURSDAY AND FRIDAY LIKELY
TO BE DRIER ALTHOUGH WIDELY SCATTERED SHOWERS STILL POSSIBLE.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 140 AM EDT FRIDAY...
BROAD AREA OF STRATUS HAD SPREAD WEST ACROSS THE REGION. THE
WESTERN EDGE WAS CLOSE TO KLWB AND KBLF. THESE AIRPORTS MAY GO
BACK AND FORTH BETWEEN SCATTERED VFR CLOUDS AND MVFR CEILINGS
THROUGH 14Z/10AM. FOR KBCB/KROA/KDAN AND KLYH HIGHER CONFIDENCE
THAT CEILINGS WILL LOWER TO MVFR OR IFR.
IMPROVEMENT IN CONDITIONS WILL BE SLOW THIS MORNING AS A FRONT
LIFTS NORTH THROUGH THE AREA. ONLY MEDIUM CONFIDENCE AS TO WHEN
CEILINGS WILL LIFT BACK TO VFR. THE THREAT OF SHOWERS AND
THUNDERSTORMS THROUGH THE TAF PERIOD REMAINS LOW ENOUGH TO KEEP
OUT OF THE FORECAST FOR NOW.
EXTENDED DISCUSSION...
ANY ISOLATED OR SCATTERED SHOWERS AND STORMS WILL BE MAINLY
ALONG AND NORTH OF A KHSP-KFVX LINE THIS EVENING...JUST SOUTH OF
THE AGAIN STALLED FRONTAL BOUNDARY.
LATE TONIGHT THROUGH SUNDAY EVENING AN AREA OF LOW PRESSURE WILL
HEAD EASTWARD THROUGH THE GREAT LAKES REGION TOWARD NEW ENGLAND.
ITS ASSOCIATED COLD FRONT WILL SWEEP THROUGH THE REGION BRINGING A
GENEROUS COVERAGE OF SHOWERS AND SOME STORMS. SUB-VFR CONDITIONS
ARE EXPECTED TO ACCOMPANY THE SYSTEM AND PRECIPITATION.
ANOTHER COLD FRONT IS EXPECTED TO PRODUCE SIMILAR CONDITIONS TUESDAY
INTO WEDNESDAY. HOWEVER...MODEL GUIDANCE FOR THIS ONE OFFERS
PRECIPITATION IN A MORE SCATTERED DISTRIBUTION. AS SUCH...THE
MAGNITUDE OF SUB-VFR CONDITIONS MAY BE LESS.
&&
.EQUIPMENT...
AS OF 730 AM EDT FRIDAY ...
THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WILL
BE OUT OF SERVICE UNTIL FURTHER NOTICE. A PART HAS BEEN BACK-ORDERED.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...DS
NEAR TERM...DS/JH
SHORT TERM...PC
LONG TERM...PC
AVIATION...AMS/JH
EQUIPMENT...AMS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
321 AM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 321 AM CDT SAT AUG 30 2014
MAIN FORECAST CONCERN IS WITH THE RAIN CHANCES TODAY AND FROM
SUNDAY NIGHT INTO MONDAY.
LOCAL AND REGIONAL RADARS SHOWING A LARGE AREA OF RAIN LIFTING
NORTHEAST ACROSS EASTERN MINNESOTA AND MUCH OF WISCONSIN. SOME
TRAILING RAIN STILL BACK ACROSS EASTERN IOWA.
EXPECT THE RAIN TO CONTINUE LIFTING NORTHEAST THIS MORNING AS THE
SURFACE LOW JUST ENTERING WESTERN WISCONSIN ALSO CONTINUES TO MOVE
NORTHEAST IN CONJUNCTION WITH THE UPPER LEVEL TROUGH. THE 30.04Z
HRRR SEEMS TO HAVE A DECENT HANDLE ON THE ONGOING RAIN AND SHOWS
THE BACK EDGE ALONG THE MISSISSIPPI RIVER BY 12Z WITH MOST OF THE
AREA DRY BY 18Z. THIS IS VERY SIMILAR TO WHAT THE 30.00Z HI-RES
ARW AND NMM SHOW AND WILL PLAN TO TREND THE RAIN CHANCES IN THIS
DIRECTION. THE QUESTION THEN BECOMES IF ADDITIONAL ACTIVITY WILL
DEVELOP THIS AFTERNOON. THE 30.00Z NAM AND GFS BOTH BRING A
TRAILING SHORT WAVE TROUGH ACROSS THE AREA THIS AFTERNOON. IT DOES
APPEAR IN THE WATER VAPOR IMAGERY THAT THIS WAVE DOES EXIST AND IS
OVER EASTERN SOUTH DAKOTA. HOWEVER...THE WATER VAPOR IMAGERY ALSO
SHOWS A LOT OF DRY AIR IN PLACE BEHIND THE DEPARTING SHORT WAVE
TROUGH AND THE CONCERN BECOMES WHETHER THIS SECONDARY SHORT WAVE
TROUGH WILL HAVE ENOUGH FORCING TO CAUSE SOME ADDITIONAL
DEVELOPMENT. THE HRRR IS SUGGESTING THAT SOME COULD START TO FORM
EARLY IN THE AFTERNOON WHICH IS SIMILAR TO THE NAM AND GFS WHILE
THE ARW AND NMM REMAIN DRY THROUGH THE AFTERNOON. WITH ALL THE DRY
AIR...TEND TO FEEL THE ARW AND NMM HAVE THE MORE CORRECT SOLUTION
BUT WILL HOLD ONTO A SMALL RAIN CHANCE JUST IN CASE SOMETHING DOES
POP UP.
AFTER SOME WEAK UPPER LEVEL RIDGING MOVES OVER THE UPPER MIDWEST
TONIGHT AND SUNDAY...THE NEXT SYSTEM WILL TAKE AIM AT THE REGION.
WATER VAPOR IMAGERY ALREADY SHOWS IT APPROACHING THE PACIFIC
NORTHWEST COAST AND IT IS EXPECTED TO MOVE QUICKLY ACROSS THE
NORTHERN ROCKIES AND ACROSS THE UPPER MIDWEST SUNDAY NIGHT AND
MONDAY. THE GFS AND 30.00Z ECMWF BOTH CONTINUE TO SHOW THIS SYSTEM
PRODUCING MODERATE TO STRONG PV ADVECTION IN THE 500-300 MB LAYER
LATE SUNDAY NIGHT INTO MONDAY MORNING. THE GFS SHOWS STRONG
ISENTROPIC UP GLIDE SHOULD SPREAD ACROSS THE AREA SUNDAY NIGHT
AHEAD OF THE SHORT WAVE TROUGH WITH UP TO 10 UBAR/S ON THE 305K
SURFACE. THE NOSE OF THE LOW LEVEL JET IS EXPECTED TO BECOME
ORIENTED INTO THE AREA SUNDAY EVENING WITH LITTLE MOVEMENT SUNDAY
NIGHT BEFORE VEERING OFF TO THE EAST MONDAY MORNING. WITH THE
AMPLE FORCING...WIDESPREAD SHOWERS AND STORMS ARE EXPECTED TO MOVE
IN SUNDAY EVENING AND WORK EAST ACROSS THE AREA BEFORE ENDING
MONDAY AFTERNOON. GOOD CAPE WILL BUILD SUNDAY AFTERNOON WEST OF
THE AREA AHEAD OF THE COLD FRONT ASSOCIATED WITH THIS SYSTEM. THE
GFS SUGGESTS THAT AN AXIS OF 1000-1500 J/KG OF ML CAPE WILL
PERSIST AHEAD OF THE FRONT THROUGH THE NIGHT AS THE SYSTEM WORKS
ACROSS THE AREA. GOOD SHEAR LOOKS TO OVERSPREAD THE REGION WITH 40
TO 50 KNOTS OF 0-6KM SHEAR...BUT MOST OF THIS LOOKS TO BE IN THE
0-3KM LAYER WITH 35 TO 40 KNOTS. EXPECT THAT THIS WILL BE
SUFFICIENT TO SUPPORT SOME STRONG TO SEVERE STORMS WITH HAIL AND
WIND THE MAIN THREATS.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 321 AM CDT SAT AUG 30 2014
SOME SMALL RAIN CHANCES WILL CONTINUE INTO TUESDAY AS A SECONDARY
SHORT WAVE TROUGH LOOKS TO SWEEP ACROSS THE UPPER MIDWEST.
AGAIN...THERE SHOULD BE GOOD DRYING SO THE QUESTION BECOMES IF THE
FORCING WILL BE ENOUGH TO GENERATE SOME ACTIVITY. AFTER
THAT...RIDGING LOOKS TO BUILD OVER THE REGION FOR A SHORT PERIOD
WEDNESDAY AND WEDNESDAY NIGHT. THE FLOW THEN SHOULD BECOME
SOUTHWEST ALLOWING A POSITIVE TILT LONG WAVE TROUGH TO APPROACH
FROM THE NORTHWEST. DIFFERENCES BETWEEN THE ECMWF AND GFS ON HOW
FAST THIS TROUGH MOVES THROUGH WITH THE ECMWF CONSIDERABLY FASTER.
WILL HAVE SOME RAIN CHANCES WITH THIS SYSTEM BUT WILL UNDERCUT THE
MODEL CONSENSUS GRIDS SOME THINKING THE RIDGE WILL BE THE DOMINANT
FEATURE THROUGH THE END OF THE PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1134 PM CDT FRI AUG 29 2014
HEAVIEST RAINFALL HAS MOVED NORTH AND EAST OF TAF AIRFIELDS...
ALTHOUGH SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE THROUGH
THE NIGHT. VISIBILITY IN THE STRONGEST OF STORMS COULD BE REDUCED
TO 1SM...BUT BIGGER CONCERN IS THE POTENTIAL FOR PATCHY FOG/MIST.
DESPITE ABUNDANT VFR/MVFR CEILINGS OVERNIGHT...RECENT RAIN HAS
RESULTED IN A NEARLY SATURATED NEAR SURFACE LAYER WITH CURRENT DEW
POINT DEPRESSIONS OF 2-3 DEGREES. WOULD EXPECT TO SEE SOME
REDUCTION IN VISIBILITY IN MIST AFTER 30.08Z IN THE 3 TO 5SM
RANGE AND POSSIBLY LOWER. WILL AMEND AS NECESSARY. CONDITIONS
WILL SLOWLY IMPROVE SATURDAY MORNING WITH A RETURN TO VFR
CONDITIONS BY THE AFTERNOON. WINDS THROUGH THE PERIOD WILL BE
LIGHT AND VARIABLE WITH A SLIGHT NORTHWEST DIRECTIONAL PREFERENCE.
&&
.HYDROLOGY...
ISSUED AT 321 AM CDT SAT AUG 30 2014
ADDITIONAL RAINFALL TODAY WILL BE A QUARTER INCH OR LESS AND THIS
WILL NOT BE ENOUGH TO CAUSE ANY FLOODING PROBLEMS. WITH THE SYSTEM
THAT WILL AFFECT THE AREA SUNDAY NIGHT AND MONDAY...CURRENT
EXPECTATIONS ARE THAT THE RAIN TOTALS WILL BE AN INCH OR LESS. THE
PRECIPITABLE WATER IS NOT EXPECTED TO BE QUITE AS HIGH WITH THE
GFS SHOWING AROUND 1.75 INCHES BUT WARM CLOUD DEPTHS WILL STILL BE
IN THE 3.5 TO 4 KM RANGE. THE SHOWERS AND STORMS WILL HAVE THE
POTENTIAL TO PRODUCE SOME HIGHER RAIN RATES...BUT WITH THE
CONVECTION EXPECTED TO BE PROGRESSIVE...IT SHOULD NOT POSE ANY
LARGE SCALE FLOODING PROBLEMS AND PLAN TO ISSUE THE LAST ESF THIS
MORNING STATING THIS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...ROGERS
HYDROLOGY...04
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
319 AM CDT SAT AUG 30 2014
.TODAY...FORECAST CONFIDENCE IS MEDIUM.
A WELL DEFINED MID LEVEL SHORT WAVE OVER CENTRAL IOWA EARLY THIS
MORNING WILL LIFT NORTHEAST AND TRACK TO NEAR GREEN BAY BY EARLY
THIS AFTERNOON. THE ASSOCIATED SURFACE LOW WILL TAKE A SIMILAR PATH.
THE FIRST ROUND OF SHOWERS AND STORMS IS EXITING TO THE NORTH OF THE
FORECAST AREA EARLY THIS MORNING. THIS STUFF WAS GENERALLY
ASSOCIATED WITH A FAVORABLE COMBINATION OF A LOW LEVEL JET AND SOME
UPPER LEVEL DIVERGENCE FROM THE RIGHT ENTRANCE REGION OF UPPER JET.
A SECOND ROUND SHOULD LIFT UP HERE BETWEEN 09-13Z THIS
MORNING...MORE DIRECTLY TIED TO THE CIRCULATION OF THE MID LEVEL
SHORT WAVE. THE HRRR DOESN/T DO MUCH WITH THIS SECOND ROUND...IN
FACT WEAKENING IT AS IT GETS UP HERE. WILL TRY TO REFINE THE TIMING
OF POPS AND COVERAGE TO MATCH THESE TRENDS. THE AFTERNOON COULD
FEATURE SCATTERED DIURNAL SHOWERS AND A POSSIBLE THUNDERSTORM AS THE
UPPER TROF AXIS MOVES THROUGH. THE SHOWERS/STORMS ARE MOVING
QUICKLY...SO DESPITE THE HIGH MOISTURE CONTENT OF THE
COLUMN...FLOODING CONCERNS ARE NIL. HIGHS WILL BE IN THE 70S WITH
DEWPOINTS REMAINING HIGH...SO IT WILL FEEL MUGGY OUT THERE.
.TONIGHT...FORECAST CONFIDENCE IS MEDIUM.
SOME OF THE MODELS ARE DEPICTING SOME SHOWERS INTO THE EVENING WITH
A SECONDARY SHORT WAVE EXITING...BUT THE COLUMN IS DRYING OUT AND
THE BEST FORCING MOVES EAST. SO AT THIS POINT...WILL CONTINUE THE
DRY FORECAST. STILL HUMID WITH ELEVATED DEWPOINTS OVERNIGHT. THE
PATTERN TURNS RATHER BAGGY WITH LIGHT TO CALM WINDS...SO WILL THROW
IN SOME PATCHY FOG AFTER MIDNIGHT.
.SUNDAY AND MONDAY...FORECAST CONFIDENCE...MEDIUM
SUNDAY LOOKS LIKE A PLEASANT DAY WITH A FAIR AMOUNT OF SUNSHINE.
MODELS ARE SHOWING A WEAK WAVE PASSING THROUGH...BUT MODELS ARE
SHOWING A GOOD AMOUNT OF DRY AIR IN THE MID AND UPPER LEVELS...SO
KEPT THE FORECAST DRY. HIGH TEMPS SHOULD BE A FEW DEGREES ABOVE
NORMAL.
SHOWERS AND STORMS ARE LIKELY IN THE WEST BY DAYBREAK MONDAY
MORNING AND THEN ACROSS THE FORECAST AREA DURING THE DAY AS A
COLD FRONT MOVES THROUGH. SOME STRONG TO SEVERE STORMS ARE
POSSIBLE...BUT THIS WILL BE DEPENDENT ON THE TIMING OF THE FRONT.
IT LOOKS LIKE A DECENT AMOUNT OF INSTABILITY TO GO ALONG WITH
AROUND 45 KNOTS OF 0-6 KM BULK SHEAR. SPC DAY 3 CONVECTIVE
OUTLOOK HAS THE SOUTHERN FORECAST AREA IN A SLIGHT RISK FOR
SEVERE STORMS.
.TUESDAY THROUGH FRIDAY...FORECAST CONFIDENCE...MEDIUM
IT LOOKS MAINLY DRY TUESDAY AND WEDNESDAY AS SURFACE HIGH PRESSURE
SLIDES THROUGH THE AREA. A COUPLE MODELS ARE SHOWING A WEAK WAVE
OR TWO BRINGING SOME SPLOTCHY QPF HERE AND THERE...BUT NOT SEEING
A CONSISTENT SIGNAL AT THIS POINT SO KEPT THE FORECAST DRY.
A RETURN OF MOISTURE UNDER SOUTHERLY LOW LEVEL FLOW IS EXPECTED TO
BRING A CHANCE FOR SHOWERS AND STORMS BACK TO THE AREA THURSDAY
AND FRIDAY.
TEMPERATURES FOR THE TUESDAY THROUGH FRIDAY TIME PERIOD SHOULD
REMAIN NEAR TO A COUPLE DEGREES ABOVE NORMAL.
&&
.AVIATION/12Z TAFS/...MVFR TO IFR CIGS SHOULD OVERSPREAD SOUTHERN
WISCONSIN EARLY THIS MORNING...THEN GRADUALLY IMPROVE TO VFR THIS
AFTERNOON AS LOW PRESSURE PASSES BY TO THE NORTH. MOSTLY PLACES
SHOULD BE VFR BY 19-20Z. DRIER AIR SHOULD EVENTUALLY WORK IN ON
INCREASING SOUTHWEST THEN WESTERLY WINDS. WINDS BECOME LIGHT
TONIGHT AND WITH LINGERING HIGH DEWPOINTS...WE MAY SEE SOME PATCHY
FOG AFTER MIDNIGHT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION...DAVIS
SUNDAY THROUGH FRIDAY...DDV
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1053 PM MDT FRI AUG 29 2014
.UPDATE...
ISSUED AT 904 PM MDT FRI AUG 29 2014
UPDATED THE GRIDS TO REMOVE ALL MENTION OF SHOWERS AND THUNDERSTORMS
OVERNIGHT BASED ON RADAR TRENDS AND LATEST MODEL GUIDANCE. ALSO
ADJUSTED TEMPERATURES...DEWPOINTS...WINDS AND CLOUD COVER BASED
ON TRENDS.
UPDATE ISSUED AT 600 PM MDT FRI AUG 29 2014
GRIDDED FORECASTS UPDATED TO MODIFY THE EVENING POPS WITH ISOLATED
THUNDERSTORMS FROM SARATOGA TO CHEYENNE...THEN DRY AFTER 9 PM.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 150 PM MDT FRI AUG 29 2014
A WELL-DEFINED SHORTWAVE CONTINUES TO SLIDE EASTWARD ACROSS THE CWA
THIS AFTN ALONG THE NORTHERN FRINGE OF BROAD UPPER-LEVEL RIDGING IN
PLACE OVER THE CENTRAL ROCKIES. WATER VAPOR SATELLITE SHOWED THIS
FEATURE OVER NORTHEAST WY AS OF 19Z MOVING QUICKLY TOWARD SOUTHWEST
SD AND THE NORTHERN PANHANDLE. CONVECTIVE CHANCES ARE THE MAIN ISSUE
IN THE NEAR TERM. ASIDE FROM MOUNTAIN CONVECTION...SHOWER AND TSTM
CHANCES WILL BE ASSOCIATED WITH LARGER SCALE FORCING IN ADVANCE OF
THE AFOREMENTIONED WAVE. THE NAM IS STILL THE MOST BULLISH WITH QPF
OVER OUR NORTHEAST ZONES WHILE THE HRRR COMPOSITE REFLECTIVITY SHOWS
FAIRLY MODEST CONVECTIVE COVERAGE. CONFIDENCE IS FAIRLY LOW IN JUST
HOW WIDESPREAD THINGS WILL BE TODAY GIVEN WEAK SUBSIDENCE BENEATH
THE RIDGE...AND RECENT RADAR ECHOS HAVE NOT BEEN ANYTHING TO WRITE
HOME ABOUT. BELIEVE WE WILL SEE SOME MID AFTN TSTM ACTIVITY THOUGH
OVER THE HIGH PLAINS. CURRENT SPEED OF THE TROUGH AXIS SUGGESTS THE
BEST FORCING FOR ASCENT AND MOISTURE WILL SHIFT EAST OF THE CWA BY
ABOUT 22Z...AFTER WHICH TIME TSTMS SHOULD DIMINISH. DESPITE GOOD SFC
HEATING TODAY...LATEST SPC MESOSCALE ANALYSIS INDICATES LESS THAN
1000 J/KG OF SBCAPE. LLVL FLOW OUT OF THE NORTH OR NORTHWEST IS NOT
CONTRIBUTING TO ANY REASONABLE SHEAR PROFILES EITHER SO ANY STRONGER
STORMS SHOULD NOT BE WIDESPREAD THOUGH THEY ARE POSSIBLE. IT SHOULD
BE A QUIET OVERNIGHT WITH AS SUBSIDENCE INCREASES OVER THE CWA. DO
NOT EXPECT FOG DEVELOPMENT TONIGHT WITH UNFAVORABLE LLVL WINDS...BUT
CANNOT RULE IT OUT IN THE PLATTE RIVER VALLEY IF WINDS ARE MORE
SOUTHEAST THAN CURRENTLY PROGGED.
SAT STILL LOOKS TO BE THE WARMEST DAY OF THE PERIOD WITH A VIGOROUS
UPPER-LEVEL TROUGH LURKING OVER THE PACIFIC NW. THERMAL RIDGE AXIS
BUILDS INTO THE CWA WITH NAM H7 TEMPS INCREASING TO 13-14 C FROM THE
LARAMIE RANGE EASTWARD. MOST MOS GUIDANCE SUGGESTS HIGHS IN THE 83
TO 93 DEGREE RANGE OVER THE PLAINS...AND THIS LOOKS REASONABLE GIVEN
THE SYNOPTIC SETUP. THE PROGRESSION OF THE TROUGH AND ASSOCIATED SFC
COLD FRONT APPEARS A BIT SLOWER THAN EARLIER MODELS SUGGESTED...SO
THIS SHOULD DELAY PCPN CHANCES UNTIL MID TO LATE AFTN ON SAT. MIDLVL
QG FIELDS SHOW GOOD ASCENT SPREADING FROM WEST TO EAST AFTER 21Z ON
SAT. THIS OCCURS ALONG WITH LLVL CONVERGENCE ASSOCIATED WITH A
STRONG SFC COLD FRONT MOVING ACROSS THE CWA...SO AM CONFIDENT IN AT
LEAST SCATTERED COVERAGE OF SHOWERS AND TSTMS. INSTABILITY COULD BE
WANING BY THE TIME CONVECTION MOVES FAR ENOUGH EAST...BUT CAN NOT
RULE OUT A STRONG OR LOCALLY SEVERE STORM WITH NAM CAPES AROUND 1500
J/KG BENEATH STEEP MIDLVL LAPSE RATES AND ABOUT 30 KTS OF H5 FLOW.
IT WILL BE BREEZY ON SAT AFTN AND EARLY EVE...ESPECIALLY ALONG AND
WEST OF THE LARAMIE RANGE AS HEIGHT GRADIENTS INCREASE ALOFT AND A
STRONG SFC LOW MOVES ACROSS NORTHERN WY. WSW H7 WINDS AROUND 35 TO
40 KTS SUGGEST STRONGER WINDS OVER THE WIND PRONE AREAS...SO BUMPED
UP GUSTS TO AROUND 45 MPH AT ARL AND BRX.
SHOWERS WILL INCREASE OVERNIGHT THROUGH SUN AM...AND COULD CONTINUE
THROUGH MUCH OF THE AFTN WITH COLDER AIR ALOFT AS THE TROUGH MOVES
OVERHEAD. THE MODELS SHOW H7 TEMPS PLUNGING INTO THE MID SINGLE
DIGITS C ON SUN IN THE POST-FROPA AIR MASS. LOOKING FOR HIGHS TO BE
SOME 10 TO 15 DEGREES COOLER THAN SAT. FLOW ALOFT BRIEFLY BECOMES
MORE ZONAL BY LATE SUN NIGHT...WITH THE ECMWF FINALLY STARTING TO
BACK OFF ON QPF BY ABOUT 06Z MON.
.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 150 PM MDT FRI AUG 29 2014
SHORTWAVE TROUGH DRIVEN BY A 100+KT JET STREAK WILL SWEEP ACROSS
THE CWFA ON MONDAY. A QUICK SHOT OF MOISTURE ALONG WITH A WEAK
COLD FRONT WILL PRODUCE PERHAPS SOME AM SHOWER ACTIVITY ACROSS
CARBON AND CONVERSE COUNTIES. BETTER CONVECTIVE CHANCES WILL AWAIT
MONDAY AFTERNOON AS WEAK INSTABILITY IS REALIZED. PROGD SBCAPES
OF AROUND 500 J/KG SUGGEST THAT MOST OF THE CONVECTION WILL BE OF
THE WEAK VARIETY. HOWEVER WITH A STRONG JET OVERHEAD RESULTING IN
AROUND 50 KNOTS OF DEEP LAYER SHEAR...CANT ENTIRELY RULE OUT A FEW
STORMS BECOMING STRONG...ESPECIALLY OVR THE WRN NEBRASKA PANHANDLE
LATE IN THE AFTERNOON. CONVECTIVE CHANCES WILL COME TO AN END
QUICKLY MONDAY EVENING. A DRY ZONAL PATTERN WILL ENSUE ACROSS THE
INTERMOUNTAIN WEST BEHIND MONDAYS DEPARTING SHORTWAVE TROF. THIS
WILL BRING A DRY AND UNSEASONABLY WARM PERIOD INTO THE REGION. H7
TEMPERATURE PROGS INCREASE TO 14-16C...WHICH WILL YIELD DAILY HIGH
TEMPERATURES THAT WILL REACH THE 80S AND LOW 90S EAST OF THE
LARAMIE RANGE...WITH 70S OVR CARBON/ALBANY COUNTIES. THESE ABOVE
AVERAGE TEMPERATURES WILL COMBINE WITH BREEZY CONDITIONS AND AN
ALREADY DRY AIR MASS TO HEIGHTEN FIRE WEATHER CONCERNS WEDNESDAY
AND THURSDAY. LATEST MODEL GUIDANCE CONTINUES TO POINT TO EITHER
DEVELOPING ACROSS ACROSS THE PACNW OR PERHAPS A CUT-OFF JUST OFF
THE CALIFORNIA COAST LATE IN THE WEEK. IN EITHER CASE...SOUTHWEST
FLOW INTO THE ROCKYS WILL PROVIDE A FAVORABLE TRAJECTORY FOR
MOISTURE TO RETURN TO THE CWFA AS EARLY AS THURSDAY NIGHT...BUT
MORE SO FOR FRIDAY. TEMPERATURES WILL ALSO BE A TAD COOLER FRIDAY
AS A THICKER CLOUD CANOPY PREVENTS FULL INSOLATION.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY EVENING)
ISSUED AT 1050 PM MDT FRI AUG 29 2014
ISOLATED THUNDERSTORMS CONTINUE ALONG THE WYOMING/COLORADO STATE
LINE WITH MOVEMENT TOWARDS THE SOUTHEAST. SHOULD NOT IMPACT ANY OF
OUR AIRPORTS THROUGH THE OVERNIGHT HOURS. VFR CONDITIONS EXPECTED
THROUGH THE OVERNIGHT AND MORNING HOURS WITH CONVECTION INCREASING
SATURDAY AFTERNOON. STILL TOO EARLY TO NAIL DOWN SPECIFIC TIMING
OF THUNDERSTORMS...SO JUST WENT WITH VCTS WORDING IN TAFS. LATER
SHIFTS CAN MORE ACCURATELY TIME THUNDERSTORMS...BUT LOOKS LIKE
MAYBE 21Z THROUGH 01Z OR SO FOR BEST COVERAGE.
&&
.FIRE WEATHER...
ISSUED AT 150 PM MDT FRI AUG 29 2014
NO CONCERNS FOR CRITICAL FIRE WEATHER IN THE NEAR FUTURE. A STRONG
WEATHER DISTURBANCE AND ASSOCIATED COLD FRONT WILL SWEEP ACROSS THE
AREA ON SAT AFTN THROUGH SUN MORNING. SHOWERS AND TSTMS WILL DEVELOP
FROM WEST TO EAST ACROSS SOUTHEAST WY AND THE WESTERN NE PANHANDLE
DURING THAT TIME. GUSTY WEST-TO-SOUTHWEST WINDS WILL OCCUR ALONG AND
WEST OF THE LARAMIE RANGE ON SAT WITH GUSTS OF 35 TO 45 MPH...BUT
MINIMUM RH VALUES SHOULD REMAIN ABOVE 20 PERCENT. COOLER ON SUN WITH
CONTINUED BREEZY CONDITIONS AND ISOLATED TO SCATTERED SHOWERS AND
WEAK TSTMS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...RUBIN
SHORT TERM...HAMMER
LONG TERM...HAHN
AVIATION...CLAYCOMB
FIRE WEATHER...HAMMER
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
948 AM EDT SAT AUG 30 2014
.UPDATE...
12Z TBW SOUNDING DEPICTS A UNIFORMLY MOIST ATMOSPHERE WITH
PRECIPITABLE WATER CLOSE TO 2 INCHES. MORE IMPORTANTLY...THERE HAS
BEEN SOME COOLING IN THE 700 TO 500 MB LAYER SINCE THIS TIME
YESTERDAY WHICH WILL GIVE US STEEPER LAPSE RATES AND MORE ROBUST
UPDRAFTS IN THUNDERSTORMS. IT MAY TAKE A BIT LONGER THAN USUAL TO
GET THROUGH A WEAK WARM LAYER NEAR 800 MBS...BUT ONCE IT DOES
THERE IS NOTHING LEFT TO LIMIT RAIN POTENTIAL TODAY. MOST OF THE
CONVECTION ALLOWING MODELS...LOCAL AND NATIONALLY RUN...ARE
SHOWING A LATE AFTERNOON SEA BREEZE COLLISION ALONG THE COAST NEAR
THE I-75 CORRIDOR SOUTH OF THE NATURE COAST. A QUICK GLANCE AT THE
11Z HRRR IS IN EXCELLENT AGREEMENT WITH THE ABOVE SCENARIO...WHICH
LENDS CONFIDENCE TO MUCH HIGHER RAIN CHANCES ALONG THE COAST. THE
ONLY QUESTION IS IN TIMING. RIGHT NOW IT LOOKS LIKE MOST OF THE
RAIN WILL BE AFTER 5 PM...AND IT COULD EVEN BE CLOSER TO 7 OR 8
PM. THIS WILL DEPEND ON THE TIMING AND STRENGTH OF THE SEA BREEZES
ALONG BOTH THE EAST AND WEST COAST. WINDS THROUGH 15KFT ARE ALL
EASTERLY SO ANY EAST COAST SEA BREEZE ACTIVITY WILL DEFINITELY
MOVE TOWARD OUR SIDE OF THE STATE. THE QUESTION IS SPEED. OVERALL
STORM MOTION OUTSIDE OF SEA BREEZE AND OUTFLOW BOUNDARIES WILL BE
SLOW...LIKELY ONLY AROUND 5 MPH TOWARD THE NORTHWEST. MAIN THREAT
WILL BE LOCALLY HEAVY RAIN AND OF COURSE PLENTY OF LIGHTNING. IF
YOU HAVE OUTDOOR PLANS NEAR AND WEST OF THE I-75 CORRIDOR THIS
AFTERNOON AND EVENING...IT WOULD BE A GOOD IDEA TO KEEP AN EYE ON
THE WEATHER.
&&
.AVIATION...
BEST CHANCE FOR IFR/LIFR CONDITIONS WILL BE AT THE COASTAL
TERMINALS WHERE HIGHEST COVERAGE OF SEA BREEZE INDUCED STORMS IS
EXPECTED. TIMING MAY BE LATER THAN USUAL...POSSIBLY EVEN CLOSER TO
00Z. WILL CONTINUE TO HANDLE WITH VCTS UNTIL CONFIDENCE IN TIMING
INCREASES.
&&
.MARINE...
HIGH PRESSURE OVER THE ATLANTIC CONTINUES TO RIDGE WEST OVER THE
FLORIDA PENINSULA PRODUCING EAST SOUTHEAST WINDS LESS THAN 15 KNOTS
AND SEAS 2 TO 3 FEET FOR THE WEEKEND AND INTO NEXT WEEK. THE SEA
BREEZE WILL SET UP ALONG THE COASTLINE EACH DAY TURNING THE WINDS
TO AN ONSHORE FLOW OUT OF THE SOUTHWEST THROUGH NORTHWEST DIRECTION.
SCATTERED SHOWERS AND STORMS WILL BE POSSIBLE EACH DAY OVER THE
COASTAL WATERS...PRODUCING GUSTY WINDS AND HIGHER SEAS IN THE
VICINITY OF THESE STORMS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 93 77 93 78 / 80 40 40 30
FMY 93 75 94 76 / 60 20 40 30
GIF 93 75 94 75 / 60 20 40 20
SRQ 92 76 94 75 / 80 30 40 30
BKV 94 74 94 73 / 70 30 40 20
SPG 93 80 93 79 / 70 40 40 30
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE/AVIATION...JILLSON
MARINE...WYNN
DECISION SUPPORT...MROCZKA
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1052 AM CDT Sat Aug 30 2014
.UPDATE...
ISSUED AT 1052 AM CDT SAT AUG 30 2014
Much of central Illinois remains convection-free this morning,
except for the far SE KILX CWA south of I-70 where showers and
thunderstorms are ongoing. 15z/10am visible satellite imagery is
beginning to show an enhanced band of Cu along the Illinois River
that will eventually become a broken line of thunderstorms this
afternoon. HRRR shows storms developing along the I-55 corridor
after 20z, so have adjusted PoPs accordingly. Have focused likely
PoPs along/east of I-55 by mid-afternoon into the early evening
hours. Further west, will only carry low chances along/west of the
Illinois River this afternoon, then dry by evening.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 401 AM CDT SAT AUG 30 2014
Lift associated with an upper level shortwave trough over eastern
Iowa moving east-northeastward this morning is providing a focus for
a line of convection moving into western Illinois while a weaker
line of showers roughly along I-57 continues in eastern Illinois.
Cold front associated with the trough to our west is expected to
move to around to IA/IL border and stall out as the upper level
shortwave lifts northeastward bringing a continued focus for
precipitation for much of the next 24 hours. Rich moisture of close
to 2 inches will continue to stream into southeast Illinois to bring
the best chances for precipitation in that region. Tonight, as the
main trough shifts eastward, drier air continues to push eastward
allowing drier conditions to spread eastward into Illinois. As a
result, have pops trending downward overnight. Temperatures will be
down slightly today and tonight.
&&
.LONG TERM...(Sunday through Friday)
ISSUED AT 401 AM CDT SAT AUG 30 2014
Lingered a chance of showers and thunderstorms over southeast IL
Sunday where more clouds will be over eastern/se IL. Best chances of
convection will be southeast of Ohio river across KY where short
wave energy will be. Highs in the low to mid 80s Sunday (warmest
over western areas) and humid with dewpoints mostly in the lower
70s. Dry conditions across area Sunday evening then have chance of
showers and thunderstorms returning to areas nw of I-55 overnight
Sunday night. This due to approaching strong upper level trof over
Pacific Northwest that brings a cold front se through IL Monday
night. Quite warm and humid again on Monday with highs in the 80s
and dewpoints in the lower to middle 70s. Chances of showers and
thunderstorms increase from nw to se during the day Monday with
highest chances Monday afternoon/evening, gradually shifting chances
se overnight Monday night. SPC has much of central IL in a slight
chance of severe storms Monday afternoon/evening for damaging winds
and large hail. Surface to 6km bulk shear around 40 kts and CAPES
2-3K J/Kg supports this risk of severe storms from I-70 nw.
Upper level flow to become zonal by middle of next week and frontal
boundary likely not to get too far south of IL. Thus will continue
chances of showers and thunderstorms Tue with best chances (40-50%)
in southeast IL closer to frontal boundary while slight chances nw
of IL river. Just slight chances by Wed-Thu night and quite warm and
humid with highs in the mid to upper 80s and even approaching
lower 90s over southern areas Thu and Friday. This is due to
upper level ridge of 593 dm 500 mb high building over KY/TN. Next
frontal boundary to press se toward IL later Friday into Saturday
of next week increasing chances of showers and thunderstorms followed
by cooler weather next weekend.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
ISSUED AT 658 AM CDT SAT AUG 30 2014
Scattered showers continue this morning mainly east of KDEC and
could produce isolated MVFR cig/vsby. As daytime heating
begins...expecting intensification of thunderstorm activity.
Location/timing of thunderstorms still uncertain at this time so
have limited mention to VCTS after 16Z-18Z. After 00Z...drying
conditions expected to begin spreading eastward across Illinois.
Western TAF sites KPIA-KSPI likely to see fog formation overnight
while eastern TAF sites KDEC-KCMI could see continued showers
overnight until around 12Z and have left VCSH in forecast.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BARNES
SHORT TERM...ONTON
LONG TERM...07
AVIATION...ONTON
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1041 AM EDT SAT AUG 30 2014
LATEST UPDATE...
UPDATE/MARINE
.SYNOPSIS...
ISSUED AT 327 AM EDT SAT AUG 30 2014
A LOW PRESSURE SYSTEM TRACKING THROUGH THE NORTHERN GREAT LAKES
WILL DRAG A COLD FRONT THROUGH THE SOUTHWEST LOWER MICHIGAN
TONIGHT. PERIODS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY
INTO THIS EVENING AHEAD OF THE COLD FRONT. IT WILL BE WARM AND
HUMID TODAY TOO. SUNDAY WILL FOR THE MOST PART BE PARTLY CLOUDY
WITH A SLIGHT CHANCE OF AN AFTERNOON THUNDERSTORM. IT WILL
CONTINUE TO BE WARM AND HUMID. A COLD FRONT PUSHING INTO THE AREA
ON LABOR DAY WILL BRING THE RISK FOR SEVERE STORMS IN THE
AFTERNOON. WARM AND HUMID CONDITIONS WILL CONTINUE.
&&
.UPDATE...
ISSUED AT 1032 AM EDT SAT AUG 30 2014
SATELLITE IMAGERY SHOWS DIMINISHING CLOUDS ACROSS LAKE MI. BASED
ON THE MOVEMENT...WE SHOULD SEE A PERIOD OF SUN THIS AFTERNOON.
AS A RESULT THE UPDATE FEATURES MORE SUNSHINE IN THE GRIDS. THIS
HEATING SUPPORTS THUNDERSTORMS DEVELOPING. WITH A LOW LEVEL JET
MOVING IN...THE STORMS COULD BECOME NUMEROUS. WILL KEEP THE HIGHER
POPS GOING FOR THE AFTERNOON. WILL NEED TO MONITOR THE SEVERE
POTENTIAL AS DEEP LAYER SHEAR CLIMBS ABOVE 30 KNOTS. HRRR RUC
SHOWS VERY LITTLE CONVECTION AFTER 19Z DESPITE THE ARRIVAL OF A
MID LEVEL WAVE.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 327 AM EDT SAT AUG 30 2014
WE HAVE TWO PERIODS OF CONVECTION TO WATCH IN THE SHORT TERM
FORECAST. THE THUNDERSTORMS AHEAD OF THE WEAK COLD FRONT THAT
COMES THROUGH THE AREA TONIGHT... THEN THE POSSIBLY SEVERE STORMS
ON LABOR DAY AS A STRONG JET STREAM INTERACTS WITH THE COLD FRONT
DURING MAX HEATING.
A QUICK OVERVIEW OF WHAT IS HAPPENING ON THE LARGER SCALE IS THE
SHEARING OUT SOUTHERN STREAM WAVE WE HAVE BEEN WATCHING FOR OVER
A WEEK NOW COMES THROUGH THE AREA TODAY. THE MODELS ALL SHOW THE
327 MB WAVE DEVELOPING A CLOSED UPPER LOW BY MID AFTERNOON. THE
ASSOCIATED DYNAMICS OF THE UPPER JET STREAM AND CORRESPONDING LOW
LEVEL JET WILL BRING THUNDERSTORMS TO THE AREA TODAY. THAT SYSTEM
MOVES OUT OF THE AREA LEAVING A SHORTWAVE RIDGE IN THE AREA
SUNDAY. THIS WILL RESULT IN QUIET WEATHER INTO SUNDAY NIGHT.
FINALLY A STRONG PACIFIC STORM BRINGS A NORTHERN STREAM WAVE INTO
THE AREA ON LABOR DAY. THIS WILL BRING STRONG JET DYNAMICS WITH IT
AND WILL RESULT IN A STRONG LOW LEVEL RESPONSE TO THE ASSOCIATED
COUPLED JET CORE MOVING THROUGH ON LABOR DAY.
AS FOR TODAY...THERE WILL BE TWO PERIODS OF CONVECTION. THE FIRST
WAVE IS ASSOCIATED WITH A INCREASE IN DEEP MOISTURE AND IS
LARGELY THE SYSTEM WARM FRONT COMING THROUGH. THIS HAS A LOW LEVEL
JET ASSOCIATED WITH IT AND THE AXIS OF THAT JET WILL BE FROM BTL
TO MBS BY MID MORNING. THIS WILL HELP DEVELOP STORMS OVER WESTERN
LOWER MICHIGAN THAT WILL MOVE EAST ACROSS THE STATE DURING THE
DAY. THEN THERE IS A SECOND LOW LEVEL JET ASSOCIATE WITH THE MAIN
UPPER WAVE. IT COMES ONTO SOUTHWEST MICHIGAN THIS AFTERNOON AND
INCREASE TO 35 TO 40 KNOTS NEAR LANSING BY 2 PM. THAT WILL DEVELOP
A SECOND AREA OF CONVECTION OVER WESTERN LOWER MICHIGAN THAT WILL
ALSO MOVE EAST BY LATE AFTERNOON. BY THEN MIX LAYER CAPES COULD BE
1500 J/KG SO AND THERE COULD BE AS MUCH AS 30 KNOTS OF EFFECT DEEP
LAYER SHEAR SO SOME STORMS MAY BE STRONG.
ALL OF THAT MOVES OUT LATE THIS EVENING AND SHORTWAVE RIDING
FOLLOWS SUNDAY. HOWEVER THERE IS STILL SOME INSTABILITY EVEN THOUGH
THE MID LEVELS (ABOVE 850 MB) IS RATHER DRY. I ADDED A SMALL
CHANCE OF AFTERNOON THUNDERSTORMS MOSTLY SOUTH OF I-96 IN THE
AFTERNOON FOR THAT.
THE MAIN STORY IS MONDAY WHEN THE UPPER LEVEL WAVE MOVES INTO VERY
UNSTABLE AIR. THE LOW LEVEL JET ON THE GFS IS FOCUSED ON SOUTHWEST
LOWER MICHIGAN IN THE AFTERNOON AND SHOWS OVER 3270 J/KG OF CAPE.
SO THERE IS REAL POTENTIAL FOR SEVERE STORMS.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 327 AM EDT SAT AUG 30 2014
THE MAIN FOCUS OF THE LONG TERM REMAINS ON THE SYSTEM THAT WILL BE
AFFECTING THE AREA DURING THE FIRST PART OF NEXT WEEK. THE FRONT
LOOKS TO START OUT MON EVENING TO OUR WEST YET. THIS WILL KEEP THE
THREAT OF STORMS IN THE FCST...ALTHOUGH THE THREAT OF SEVERE WEATHER
WILL BE DIMINISHING AS DIURNAL INSTABILITY WILL BE ON THE WANE A
BIT.
A RESIDUAL CHC OF SHOWERS AND STORMS WILL BE LEFT IN FOR THE DAY ON
TUE. THE FRONT LOOKS TO SINK JUST SOUTH OF THE AREA AND STALL OUT.
HOW FAR SOUTH IT STALLS IS UNCERTAIN WITH THE GFS A BIT FURTHER
SOUTH...AND THE EURO KEEPING IT CLOSER TO THE AREA. THIS FRONTAL
POSITION WILL BE IMPORTANT AS ANOTHER WAVE LOOKS TO MOVE THROUGH THE
REGION AND COULD BRING ANOTHER ROUND OF RAIN TO THE AREA ON TUE.
THE AREA SHOULD DRY OUT FOR WED WITH A RIDGE OF HIGH PRESSURE
BUILDING INTO THE AREA. THIS RIDGE WILL BE FAIRLY FLAT IN NATURE AND
WILL BE SHORT LIVED. A TROUGH EXPECTED TO COME ONSHORE OVER THE
PACIFIC NW DURING THE TUE TIME FRAME WILL PUSH A FRONTAL SYSTEM SE
INTO THE AREA LATE IN THE WEEK. PCPN CHCS WILL START ON THU AS A
WARM FRONT MOVES THROUGH THE AREA. THE COLD FRONT THEN FOLLOWS FOR
THE DAY ON FRI.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 732 AM EDT SAT AUG 30 2014
WHILE IT SHOWERS AND ISOLATED THUNDERSTORMS WILL BE AROUND TODAY
IT WOULD SEEM THE LOW LEVELS ARE DRY ENOUGH THAT CIGS/VSBY WILL
LARGELY BE VFR. I PUT VCTS THIS AFTERNOON AS IT IS EXPECTED SOME
CONVECTION WILL BE AROUND AHEAD OF THE WEAK COLD FRONT BUT THE
ACTIVITY WILL NOT BE CONCENTRATED ENOUGH TO NAIL DOWN THE TIMING
AT THIS POINT. TONIGHT ONCE THE FRONT COMES THROUGH IT WILL STALL
AND WINDS WILL BECOME LIGHT. I WOULD EXPECT LOW CIGS AND SOME IFR
FOG TO DEVELOP TOWARD SUNRISE SUNDAY.
&&
.MARINE...
ISSUED AT 1032 AM EDT SAT AUG 30 2014
WAVES RUNNING 3 TO 5 FEET ALONG THE LAKESHORE. GIVEN THE VEERING
FLOW WITH GUSTS UP AROUND 25 KNOTS...HAZARDOUS CONDITIONS WILL
PERSIST INTO THE AFTERNOON. WINDS AND WAVES WILL GRADUALLY
DIMINISH LATER THIS AFTERNOON AND INTO THE EVENING.
&&
.HYDROLOGY...
ISSUED AT 307 PM EDT FRI AUG 29 2014
HEAVY RAIN IS A RISK THROUGH SATURDAY. VERY MOIST AIRMASS WILL ADVECT
INTO MI AS PWAT VALUES GENERALLY CLIMB ABOVE 1.5 INCHES. GIVEN THE
LACK OF DIRECTIONAL SHEAR...WE COULD SEE SOME TRAINING WHICH MAY
LEAD TO THE STORMS PERSISTING. IF THIS ENDS UP OCCURRING...SOME
LOCATIONS COULD EASILY SEE OVER 2 INCHES OF RAIN.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR MIZ037-043-050-
056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...MJS
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...NJJ
AVIATION...WDM
HYDROLOGY...MJS
MARINE...MJS
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON MS
1004 AM CDT SAT AUG 30 2014
.UPDATE...OTHER THAN MOVING UP THE ONSET OF WIDESPREAD RAIN...MADE NO
OTHER CHANGES TO CURRENT FORECAST. CURRENT SURFACE ANALYSIS SHOWING
WIDESPREAD WARM TROPICAL RAINS SPREADING NORTH ACROSS NE LA/SW MS.
VERY LITTLE LIGHTNING WITH THIS AREA...PW/S NEAR 2.4 INCHES AND WET
BULB ZERO HEIGHTS AROUND 15KFT SUGGEST THAT THESE PROCESSES WILL
CONTINUE WITH HIGH PRECIPITATION EFFICIENCY AND UNDERESTIMATED RADAR
AMOUNTS.
KJAN 12 UA DATA SHOWING LAYER OF 30-40KNOT WIND FLOW BETWEEN
5 AND 20KFT. LATEST HRRR DATA IS IN AGREEMENT WITH OVERNIGHT
FORECASTERS ASSESSMENT OF A WIND THREAT TODAY IN ITS ILLUSTRATION OF
SHORT BOWING SEGMENTS IN THE FORECAST REFLECTIVITY...AS WELL
AS...FORECAST WIND GUSTS OF 30-50 KNOTS WITH THE MORE ROBUST
CONVECTION THIS AFTERNOON./26/
&&
.AVIATION...RAIN WILL BE A MORE HIT OR MISS FOR THE EASTERN AREAS
THROUGH TONIGHT. CLOUDS WERE DISSIPATING FOR HBG...GTR AND MEI. AT
THIS TIME...EXPECTING SCT-BKN CLOUDS WITH CEILINGS ABOUT 3000FT.
THUNDERSTORMS MAY DEVELOP AFTER 18Z...SO INTERMITTENT LOW CLOUDS AND
HEAVY RAIN WILL BE POSSIBLE. MAY ADD SOME TEMPO GROUPS FOR RAIN
THROUGH 3Z. GLH WILL LIKELY HAVE RAIN THROUGH THE EVENING...WITH
SOME SHORT BREAKS. EXPECTING RAIN AND/OR FOG TO MAINTAIN MVFR
CONDITIONS THROUGH MUCH OF THE FORECAST PERIOD. THROUGH THE
AFTERNOON AND EVENING LOW CLOUDS AND HEAVY RAIN MAY BRIEFLY LEAD TO
LIFR...MAYBE IFR CONDITIONS. GWO...HKS...JAN WILL SEE MORE
WIDESPREAD RAIN AFTER 18Z. WILL CONTINUE WITH VCTS...ESPECIALLY FOR
JAN/HKS BY LATE AFTERNOON. MVFR/LIFR CONDITIONS WILL BE LIKELY WITH
PERIODS OF HEAVY RAIN AND LOW CLOUDS. WILL ADD PATCHY FOG AND
STRATUS TO ALL SITES FROM 9-12Z. /7/
&&
.PREV DISCUSSION... /ISSUED 336 AM CDT SAT AUG 30 2014/
SHORT TERM...ACTIVE WEATHER DAY ON TAP AS HIGHLY MOIST AIRMASS WILL
FUEL SHRA/TSRA TODAY AS A DISTURBANCE LIFTS NORTHWARD OUT OF THE
NORTHER GULF AND S-CENTRAL SECTIONS OF LA. RECENT DAYS WE HAVE BEEN
ADVERTISING THE POTENTIAL FOR LOCALLY HEAVY RAINFALL AND SOME
POTENTIAL FOR FLASH FLOODING. THIS RISK STILL EXISTS AS EFFICIENT
RAINS WILL BE POSSIBLE AS FORCING FOR ASCENT WILL MAKE THE MOST OF
THE 2.2-2.4 IN PW AIRMASS. HOWEVER...AN ADDITIONAL THREAT FOR GUSTY
AND POSSIBLY DAMAGING WINDS EXISTS AS WELL. THE REASON FOR THIS NEW
THREAT RESIDES IN THE INCREASED FLOW BETWEEN THE 2-12 KFT LAYER.
NEARLY ALL GUIDANCE INDICATES THIS LAYER WILL CONTAIN 30-40 KTS OF
FLOW. WHILE HEATING TODAY WILL BE LIMITED AND THE THERMODYNAMIC
PROFILE WILL BE QUITE TAME...MID/UPPER 80S DEGREE TEMPS WILL SUPPORT
SBCAPE NEAR 2000 J/KG AND THIS WILL BE MORE THAN ENOUGH ENERGY TO
SUPPORT DEEP CONVECTION (ESP WITH THE DISTURBANCE PROVIDING STRONG
FORCING). FURTHERMORE...ORGANIZING CONVECTION WILL BE ABLE TO
UTILIZE THE INCREASED FLOW TO ORGANIZE COLD POOLS. IF ANY COLD POOL
ORGANIZES IN A FASHION WHERE IT MOVES IN TANDEM WITH THE FLOW BELOW
12KFT (WHICH LOOKS TO BE IN A NNE DIRECTION) BOWING SEGMENTS WILL BE
POSSIBLE AND LIKELY EFFICIENTLY BRING DOWN THE STRONGER WINDS ALOFT. IN
TURN...THIS WILL INCREASE THE WIND DAMAGE POTENTIAL. IT IS ALSO WORTH
NOTING THAT THE INCREASED FLOW WILL ALSO INCREASE THE LOW LEVEL
HELICITY TO VALUES THAT COULD SUPPORT A BRIEF TORNADO. WHILE THIS IS
NOT A PRIMARY THREAT...IT CAN`T BE RULED OUT. DUE TO ADDED
RISKS...WILL INTRODUCE A LIMITED SVR RISK FOR DAMAGING WINDS. AS FOR
A LOCATION...MOST OF THE AREA WILL HAVE A RISK...THE EXCEPTIONS LOOK
TO THE BE THE FAR SW AND THE I-59 CORRIDOR. BEST TIMING WOULD BE FROM
11AM TO 5PM. THE HWO/GRAPHICS WILL HIGHLIGHT THE TIMING AND THREAT
AREA.
AS FOR OTHER FORECAST ELEMENTS (POPS AND WEATHER)...GUIDANCE POPS
WERE HIGHER FROM THE PREV RUNS AND I FOLLOWED THOSE HIGH VALUES AND
INCREASED SOME LOCATIONS TO STAY IN LINE WITH PREV FORECASTS. THE
MAIN TIMING FOR THIS ACTIVITY WAS ADJUSTED...THE SW LOOKS TO BE THE
AREA THAT GETS IT FIRST AND EARLIEST WITH THE REMAINDER OF THE AREA
SOMETIME BETWEEN LATE MORNING AND LATE AFTERNOON. FOR THIS
EVE/OVERNIGHT...MUCH MORE OF TRICKY FORECAST EXISTS FOR TONIGHT. IT
SEEMS LIKE THERE WILL BE A LULL PERIOD FROM LATE AFTERNOON INTO MOST
OF THE EVE...THEN ACTIVITY COULD PICK UP AFTER MIDNIGHT OVER THE NW/N
AREAS. THE S HALF LOOKS TO SEE LESS ACTIVITY THAN PREV EXPECTED AS
DRIER AIR MOVES NORTHWARD IN THE WAKE OF THE MAIN S/WV.
SUNDAY LOOKS TO BE LESS ACTIVE AS WELL THANKS TO THE DRIER AIR
MOVING UP FROM THE S/SE AROUND THE EVOLVING RIDGE. STILL...ENOUGH
MOISTURE WILL EXIST FOR SOME ISO/SCT ACTIVITY. THE GFS WAS REALLY LOW
WITH POPS AND I USED A BLEND OF THE GFS/EURO FOR THE POP FORECAST.
WITH LESS PRECIP AROUND...LOOK FOR WARMER TEMPS (90-95). /CME/
LONG TERM...MONDAY THROUGH NEXT SATURDAY
NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES IN THE LOW TO MID 90S AND
TYPICAL 20-30% AFTERNOON CHANCES OF SHOWERS/STORMS THROUGH MOST OF
THE WEEK AS A HIGH PRESSURE RIDGE BUILDS OVER THE SE/CENTRAL CONUS.
THE CURRENT SYSTEM RESPONSIBLE FOR ELEVATED RAIN CHANCES THIS
WEEKEND WILL PULL OFF TO THE NE BY LABOR DAY AND A SUBTROPICAL H7-H5
RIDGE LOOKS TO BUILD IN FROM THE ATLANTIC WHILE THE NRN STREAM FLOW
BECOMES MOSTLY ZONAL. DESPITE LOW-LVL HIGH PRESSURE AXIS AND SLOWLY
BUILDING HEIGHT INFLUENCE OVER REGION MOST OF THE WEEK, PWATS WILL
REMAIN ELEVATED /NEAR 2"/ AND COMBINED WITH DAILY AFTERNOON
INSTABILITY /2000 J/KG+/, ISOLATED/SCATTERED SHOWERS/STORMS WILL BE
LIKELY. OVERALL COVERAGE WONT BE GREAT BUT FEEL BEST COVERAGE WILL
BE IN S/SE/E WHERE SEA-BREEZE CONVERGENCE AND HIGHEST PWATS WILL
EXIST. HEAT INDICES MONDAY AND TUESDAY SHOULD REACH INTO THE LOW
100S FOR A FEW HOURS WITH LOWS ONLY FALLING INTO THE LOW TO MID 70S
THROUGH MUCH OF THE WEEK.
ON TUESDAY, A SLIGHTLY STRONGER S/WV TROUGH ACROSS THE CORN BELT
WILL ATTEMPT TO BRING A BOUNDARY SOUTH TOWARDS THE REGION BUT FEEL
IT STAY NORTH AND THUS KEPT POPS/SHOWERS OUT OF FORECAST FOR
NORTHERN AREAS. FOR WEDNESDAY THROUGH FRIDAY, RIDGING WILL REMAIN
OVER AREA AND STRENGTHEN SLIGHTLY BUT SEA-BREEZE INITIATED AND
DIURNAL ACTIVITY SHOULD CONTINUE TO BE A GOOD POSSIBILITY EACH DAY.
BY SATURDAY, THE RIDGING SLIPS FARTHER WEST AND PLACES REGION IN
SLIGHTLY GREATER N/NE FLOW THAT COULD ENHANCE SHOWER COVERAGE
POSSIBILITIES. /ALLEN/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 88 73 93 74 / 87 37 22 7
MERIDIAN 90 72 93 72 / 71 27 19 7
VICKSBURG 85 73 92 72 / 96 40 25 7
HATTIESBURG 91 75 96 74 / 74 19 12 13
NATCHEZ 85 73 92 74 / 92 30 18 12
GREENVILLE 84 73 91 73 / 98 60 39 6
GREENWOOD 86 74 92 73 / 96 58 39 6
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
637 AM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT SAT AUG 30 2014
REMNANT CONVECTIVE DEBRIS WILL CONTINUE TO SLIDE SOUTHEASTWARD
ACROSS SW NEB THROUGH SUNRISE WHILE STRATUS CONTINUES TO DROP
SOUTHWARD ACROSS ERN SD. RAP LOW LEVEL RH PROGS WOULD SUGGEST THE
STRATUS WILL SAG TO NEAR THE NIOBRARA VALLEY BY 12-15Z OR SO AND THE
HRRR HAS LOW CLOUDS EVEN FURTHER SOUTH. HAVE ADJUSTED SKY COVER FOR
THAT. PREVIOUS FCST HAD MENTION OF FOG ALSO IN THE NERN ZONES AS A
RESULT OF PREVIOUS 24 HR RAINFALL AND BELIEVE THAT THIS WOULD ALSO
BE ALONG THE FRINGE OF LOWER CLOUDS WHICH IS A TYPICAL EVOLUTION
ANYWAY. SO HAVE LEFT THE MENTION OF FOG AS IT WAS...MORE PATCHY TWD
THE SWRN PORTION OF THE AREA...ALL OF WHICH SHOULD BURN OFF BY MID
MORNING. ON THE LARGER SCALE...A TRANSITORY UPPER RIDGE WILL
PROGRESS ACROSS THE AREA TODAY AS THE NRN STREAM REMAINS
ACTIVE...WITH LARGE SCALE SUBSIDENCE IN CONTROL THROUGH THE DAY.
NEXT LONG WAVE TROUGH IS DEVELOPING ACROSS THE PAC NW WITH A LEAD PV
ANOMALY MOVING QUICKLY ACROSS THE NRN ROCKIES TODAY. A LEE SIDE SFC
TROUGH WILL DEVELOP FROM WRN SD INTO THE TX PANHANDLE BY LATE
AFTERNOON AND THE RESPONSE WILL BE AN INCREASE OF SRLY WINDS AND
DEVELOPING THERMAL RIDGE ACROSS THE HIGH PLAINS. ON THE ERN EDGE OF
THE THERMAL RIDGE /WHICH WILL BE RETREATING NWD THROUGH THE DAY/
HIGHER DEW POINTS WILL EXIST. THERE IS WEAK CONVERGENCE ASSOCIATED
WITH THIS FEATURE AS IT RETREATS DURING THE DAY...BUT DEEP LAYER
LIFT DOES NOT LOOK EVIDENT. MAX TEMPS SHOULD CREEP A FEW DEGREES
HIGHER TODAY AS A RESULT OF THE DEVELOPING THERMAL RIDGE...MOST
NOTABLY IN THE SOUTHWEST AND EASTERN PANHANDLE.
ATTENTION THEN TURNS TO LOWERING HEIGHTS ACROSS THE NRN PLAINS SAT
NIGHT AND SUNDAY. LEAD PV ANOMALY /WHICH IS BEST DEFINED INITIALLY
BY 30.00Z GFS/ WILL APPROACH THE PANHANDLE BY LATE SAT
AFTERNOON...THOUGH WEAKENING AS IT MOVES INTO THE RIDGE POSITION.
CONVERGENCE ALONG THE LEE TROUGH IS WEAK INITIALLY BUT WILL LIKELY
PROVIDE ENOUGH LIFT ALONG WITH THE HIGHER TERRAIN FURTHER WEST TO
DEVELOP AT LEAST ISOLATED TSRA WHICH WILL MOVE EWD SAT EVE...THOUGH
LOW LEVELS WILL BE FAIRLY DRY AS SUGGESTED BY WRN FCST SOUNDINGS.
HIGH PLAINS NOCTURNAL LLJ DEVELOPS THROUGH SAT EVE WHICH WILL ADVECT
MID LEVEL INSTABILITY INTO THE CENTRAL PORTION OF THE STATE AND
SHOULD MAINTAIN ENOUGH DEEP LAYER LIFT TO SUPPORT ISOLATED TSRA INTO
THE WRN PORTION OF THE FCST AREA LATE EVE AND EARLY MORNING. NAM/GEM
AND GFS SUPPORT THIS THOUGH HIRES CAMS ARE NOT SO EAGER TO DEVELOP
PRECIP. GRIDS WILL INCLUDE ISOLATED TSRA MENTION...PROGRESSING
ACROSS THE AREA THROUGH SAT NIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 328 AM CDT SAT AUG 30 2014
12Z SUNDAY AND BEYOND. ZONAL UPPER LEVEL FLOW TO PREVAIL ACROSS
MUCH OF THE CONTIGUOUS 48 TO START OFF THE EXTENDED FORECAST
PERIOD...BUT THE PATTERN DOES SHIFT SLIGHTLY SOUTHWESTERLY ACROSS
THE HIGH PLAINS ON SUNDAY WITH THE APPROACH OF AN UPPER
TROPOSPHERIC NORTHERN ROCKIES SHORTWAVE. THE APPROACH OF THE
SHORTWAVE WILL ALLOW AN AREA OF SFC LOW PRESSURE AND ATTENDANT
BAROCLINIC ZONE TO MOVE EAST ACROSS THE REGION THROUGH THE DAY ON
SUNDAY...POTENTIALLY SETTING THE STAGE FOR AN ACTIVE SEVERE
WEATHER PATTERN ACROSS OUR EAST BY LATE AFTERNOON. GUIDANCE
CONTINUES TO FAVOR EAST OF A KLBF TO KANW LINE WHERE THERMAL
ADVECTION IS SHOWN AND CONVERGENCE ALONG THE BAROCLINIC ZONE WILL
BE MAXIMIZED. THE GFS...NAM...AND EC ALL SHOW CONVECTION FIRING IN
THIS AREA...SO GIVEN THE GOOD AGREEMENT OF NOT ONLY THE FINER
DETAILS BUT ALSO THE LARGER SCALE PATTERN...FELT THAT CONFIDENCE
WAS ENOUGH TO INTRODUCE LIKELY/S INTO THE FORECAST ACROSS OUR FAR
EAST /EAST OF A MAYWOOD TO NAPER LINE/...WITH SOLID CHANCE POPS
/40-50%/ FOR LOCATIONS EAST OF THE KANW TO KLBF LINE SUNDAY
AFTERNOON. THE UPPER TROPOSPHERIC FLOW REMAINS FAIRLY
PROGRESSIVE...SO STORMS SHOULD BE LARGELY REMOVED OF THE FORECAST
AREA BY 06Z MONDAY. SFC TD/S ARE PROJECTED TO REBOUND BACK INTO
THE LOWER TO MID 60S ACROSS OUR EAST AND WHEN COMBINED WITH STEEP
LOWER TO MID LEVEL LAPSE RATES WHICH PROMOTE SB POTENTIAL ENERGY
IN EXCESS OF 2500 J/KG...ROBUST UPDRAFTS ARE ANTICIPATED. DEEP
LAYER SHEAR IS SHOWN TO BE QUITE FAVORABLE FOR SEVERE
WEATHER...WITH THE MODELS PEGGING UPWARDS OF 40-50KTS 0-6KM BULK
SHEAR...LARGE HAIL WILL BE POSSIBLE. THE UPDRAFTS SHOULD QUICKLY
CONGEAL ALONG THE BAROCLINIC ZONE INTO A QUASI-LINEAR CONVECTIVE
BAND WHICH WOULD PROMOTE DAMAGING THUNDERSTORM WIND INTO THE
EVENING.
INTO EARLY NEXT WEEK...THERE REMAINS SOME DISCREPANCIES ON THE
TIMING OF THE EXITING TROUGH...MOST NOTABLY...THE EC RETAINS A PIECE
OF ENERGY WEST OF THE FORECAST AREA...BUT BRINGS IT THROUGH MONDAY
NIGHT. THE EC GENERATES LIGHT QPF ACROSS MUCH OF THE FORECAST AREA
DURING THIS TIME PERIOD. THE GFS IN COMPARISON IS DRY AND LACKS
MUCH OF THE EVIDENCE SUPPORTING THIS ADDITIONAL TROPOSPHERIC
PERTURBATION. GIVEN THE UNCERTAINTY...WENT AHEAD AND SCALED BACK
POPS MONDAY EVENING INTO EARLY TUESDAY...BUT WILL KEEP A SLIGHT
MENTION GOING.
BEYOND EARLY TUESDAY...THE CR ALLBLEND PROCEDURE PROJECTED A DRY
FORECAST THROUGH THURSDAY OF NEXT WEEK...AND THERE ARE NO ARGUMENTS
HERE AS AN OVERALL LACK OF OMEGA WOULD BE ANTICIPATED AS THE STORM
TRACK SHIFTS NORTH AND LOW AMPLITUDE RIDGING ENCOMPASSES MUCH OF THE
CONUS. LATE IN THE EXTENDED THERE MAY BE ANOTHER SHORTWAVE
IMPACTING THE CENTRAL PLAINS...HOWEVER THE MODELS SEEM TO BE BACKING
OFF THIS SOLUTION A BIT...FOCUSING THE BEST POTENTIAL WELL NORTH OF
THE CWA. WILL KEEP THE PROCEDURE UNCHANGED FOR NOW.
NOT ANTICIPATING ANY VIOLENT TEMPERATURE CHANGES THROUGH THE
EXTENDED PERIODS...BUT WITH EACH FRONTAL PASSAGE...TEMPERATURES WILL
MODERATE SOME. THE WARMEST DAY APPEARS TO COME MID-WEEK...AS HIGHS
ON WEDNESDAY ARE FORECAST TO APPROACH THE UPPER 80S TO LOWER 90S FOR
MOST LOCATIONS. OTHERWISE HIGHS IN THE 70S TO LOW TO MID 80S SHOULD
PREVAIL FOR MOST DAYS. LOWS IN THE 50S AND 60S SEEM TO BE THE NORM
OVER THE NEXT 7 DAYS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 638 AM CDT SAT AUG 30 2014
BIGGEST CONCERN WITH THE TERMINAL FCST INVOLVES PATCHY SHALLOW FOG
IN THE KLBF AREA THIS MORNING. VSBY AROUND THE KLBF TAF SITE IS HIGHLY
VARIABLE WITH SHALLOW AND PATCHY FOG SEEN IN OUTLYING AREA CURRENTLY...BUT
AS OF YET NOT AT THE SENSOR LOCATION. THREAT OF FOG SHOULD
DECREASE SUBSTANTIALLY THOUGH AFTER 15Z AS FULL SUNSHINE TAKES
OVER. IN ADDITION...SCT CLOUDS NEAR THE KVTN SITE THIS MORNING ARE
BELOW LOCAL ALTERNATE MINIMUMS...AND PATCHY FOG IS ALSO AN ISSUE
FURTHER NORTH NEAR THE SD BORDER. SHORT RANGE MODELS EVENTUALLY
MOVE THE CLOUDS EWD DURING THE MORNING HOURS SO AGAIN BY NOON
THESE CONCERNS SHOULD BE OVER.
WEAK AND ISOLATED CONVECTION IS POSSIBLE TONIGHT...MAINLY NEAR THE
KLBF SITE. HOWEVER CONFIDENCE IS LOW ON ANY PARTICULAR SOLUTION
WITHIN 24 HRS...AS NAM/GEM DEVELOP WEAK CONVECTION BUT HIRES
MODELS ARE GENERALLY DRY TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JWS
LONG TERM...JACOBS
AVIATION...JWS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
616 AM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 335 AM CDT SAT AUG 30 2014
LOW CLOUDS TODAY AND TSTM CHANCES FOR SUNDAY/SUNDAY NIGHT (WITH
SOME SEVERE WEATHER POTENTIAL) ARE THE PRIMARY FORECAST CONCERNS.
TROUGH AXIS HAD FINALLY SHIFTED EAST OF THE AREA WITH MAIN AREA OF
PCPN EARLY THIS MORNING FROM SERN MN ACROSS ERN IA AND DOWN INTO MO.
A 70 KNOT JET MAX AT 300 MB WAS NEAR THE OR/CA BORDER AT 00Z...WHICH
WAS ASSOCIATED WITH THE NEXT UPSTREAM SHORTWAVE TROUGH. 12 HOUR
HEIGHT FALLS OF UP TO 50 METERS WERE NOTED OVER SRN BC CANADA AND
WEAKER HEIGHT FALLS EXTENDED DOWN INTO NRN CA/WRN NV. OUR AREA WILL
BE MUCH DRIER TODAY WITH SHORTWAVE RIDGING BETWEEN THE DEPARTING
SYSTEM TO OUR EAST AND THE APPROACHING SYSTEM TO OUR WEST. LOW
CLOUDS WERE OVER ERN SD AND WRN IA EARLY THIS MORNING. SOME OF THE
HIGH RESOLUTION MODELS...INCLUDING THE HRRR AND RAP SHOWED THESE
OVER THE NRN AND ERN PARTS OF THE FCST AREA THIS MORNING. WILL
GENERALLY FOLLOW THIS TREND...THEN LET THE CLOUDS BREAK UP A BIT
THIS AFTN. PREVIOUS FORECAST LOOKED GOOD AND WAS IN LINE WITH A
BLEND OF MOS...SO LOOK FOR HIGHS MAINLY AROUND 80 TO 85.
TONIGHT...CLEAR TO PARTLY CLOUDY SKIES SHOULD BE THE RULE MUCH OF
THE NIGHT WITH AN INCREASE EXPECTED OVER THE WRN PARTS OF NERN
NE LATE. MODELS ARE IN GENERAL AGREEMENT THAT THIS AREA COULD ALSO
SEE SOME TSTMS BY DAYBREAK WITH MID LEVEL MOISTURE AND LIFT. THESE
WOULD THEN LIKELY DEVELOP EWD WITH TIME THE REST OF THE DAY.
THE MAIN SHOW WILL PROBABLY WAIT UNTIL LATE AFTERNOON OR EARLY
EVENING AND BE MORE TIED TO LOW LEVEL CONVERGENCE ALONG THE
APPROACHING COLD FRONT. AGREE WITH SPC DAY 2 OTLK WHICH HAS ALL
OF OUR AREA IN A SLGT RISK. ML CAPE VALUES ARE EXPECTED TO REACH
3000 TO 4000 J/KG IN THE AFTN AND LINGER INTO THE EVENING. 0 TO
6 KM BULK SHEAR VECTORS IN COMBINATION WITH EXPECTED CAPE SHOULD
BE SUFFICIENT FOR STORM ORGANIZATION. INITIALLY DISCRETE STORMS
WILL LIKELY MERGE INTO ONE OR MORE CLUSTERS AND/OR A LINE. 21Z
SUNDAY TO 06Z MONDAY SEEMS TO BE THE MOST FAVORED TIME BASED ON
FORECAST SOUNDINGS AND OTHER CURRENT MODEL DATA. IN ADDITION TO
THE SEVERE THREAT...LOCALLY HEAVY RAIN IS PROBABLY GOING TO BE AN
ISSUE DUE TO THE RECENT ISSUES WITH SOME STREAMS/RIVERS.
STORMS COULD LINGER TOWARD 12Z MONDAY NEAR THE MO BORDER BUT THE
REST OF THE DAY SHOULD BE MAINLY DRY WITH HIGHS IN THE UPPER 70S
NORTH TO LOWER 80S SOUTH.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 335 AM CDT SAT AUG 30 2014
MODELS AGREE ON GENERAL PATTERN BUT HAVE SOME DIFFERENCES WITH
DETAILS. NORTHWEST FLOW AT 500 MB TUESDAY SHOULD BECOME MORE ZONAL
WEDNESDAY AND THEN BECOME SOUTHWEST AS A TROUGH DIGS ACROSS THE
PACIFIC NORTHWEST LATER IN THE WEEK. DID NOT FAVOR ANY ONE MODEL
IN THIS PERIOD. THE 00Z ECMWF WAS WETTER MONDAY NIGHT FOR MOST OF
THE AREA...WHILE THE GFS WAS WETTER TUESDAY NIGHT/WEDNESDAY IN
SERN NE/SWRN IA.
HIGHS SHOULD BE MOSTLY IN THE 80S WITH SOME LOWER 90S POSSIBLE
SRN ZONES THURSDAY. A SLIGHT COOL DOWN SEEMS POSSIBLE FRIDAY INTO
SATURDAY WITH A DECENT CHANCE FOR SHOWERS/THUNDERSTORMS AS ANOTHER
FRONTAL SYSTEM MOVES THROUGH THE REGION.
&&
.AVIATION...(12Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 607 AM CDT SAT AUG 30 2014
REGIONAL OBS/IR SATL INDICATING BATCH OF LLVL CIGS SITUATED OVER
ERN SD WAS GRADUALLY DRIFTING SWD INTO ERN NEB THIS MORNING. GIVEN
MOVEMENT TRENDS THE LAST SEVERAL HOURS...APPEARS THAT BRIEF PD OF
IFR CONDITIONS LIKELY THIS MORNING AT KOFK/KOMA WITH VFR
CONDITIONS THEREAFTER. FOR KLNK...EXPECT VFR CONDITIONS TO
PREVAIL THERE.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...MILLER
LONG TERM...MILLER
AVIATION...DEE
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
641 AM EDT SAT AUG 30 2014
.SYNOPSIS...
LOW PRESSURE WILL MOVE ACROSS THE NORTHERN GREAT LAKES THIS
WEEKEND AND A COLD FRONT WILL MOVE TOWARD LAKE ERIE BUT THEN
BECOME STATIONARY ON SUNDAY. ANOTHER LOW WILL MOVE ACROSS THE LAKES
REGION MONDAY NIGHT AND A COLD FRONT WILL MOVE ACROSS THE AREA ON
TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLOUDS WILL BE IN THE INCREASE ESPECIALLY THIS AFTERNOON AS
SHOWERS AND THUNDERSTORMS START TO DEVELOP. CHANGED THE WORDING
OVER NW OH TO SCATTERED SHOWERS AND THUNDERSTORMS BASED ON THE
HRRR AND CURRENT RADAR TRENDS. STILL WATCHING FOR SOME SHOWERS TO
DEVELOP THIS AFTERNOON OVER NW PA BEFORE THEY DEVELOP OVER NE OH
BECAUSE OF SOME EXTRA MOISTURE MOVING UP THROUGH WESTERN PA. USED
A BLEND OF THE GUIDANCE FOR THE TEMPERATURE FORECAST AND USING THE
REASONING THAT NE OH WILL HAVE MORE SUNSHINE THEN NW OH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
THE WEEKEND WILL NOT BE A WASHOUT AND THE BEST CHANCE FOR RAIN
WILL BE SATURDAY NIGHT INTO SUNDAY.
THE POPS FOR TONIGHT ARE TOUGH. THE MODELS BRING IN MORE MOISTURE
OVERNIGHT AHEAD OF THE COLD FRONT THAT WILL NOT MAKE IT IN. BASED
ON THAT WENT WITH LIKELY POPS FOR THE NORTHERN PORTION OF THE
FORECAST AREA TONIGHT OR LATE TONIGHT AND THEN LIKELY OVER THE
SOUTHERN PORTION OF THE FORECAST AREA ON SUNDAY. CONDITIONS WILL
BE DRYING OUT FROM THE NORTH.
ON MONDAY THE REGION WILL BE IN A SOUTHWEST FLOW AND A WEAK
IMPULSE ALOFT IS EXPECTED TO MOVE THROUGH...THUS CONTINUED A 30 POP.
A COLD FRONT WILL BE APPROACHING THE AREA FOR MONDAY NIGHT INTO
TUESDAY. INCREASED THE POPS SOME BECAUSE OF THIS FEATURE.
AT THIS TIME SOME OF THE THUNDERSTORMS COULD BE STRONG TONIGHT
ESPECIALLY OVER EXTREME NW OH. THE PRECIPITABLE WATER VALUES GET
A LITTLE HIGH TONIGHT...SOME LOCALLY HEAVY RAIN IS POSSIBLE. MANY
AREAS HAVE DRIED OUT. HOWEVER...SOME LOCAL FLOOD ISSUES ARE
POSSIBLE. AT THIS TIME NO MENTION IN THE HAZARDOUS WEATHER OUTLOOK
BUT THAT MAY CHANGE.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
UPPER LEVEL RIDGE WILL MOVE EAST ACROSS THE AREA THROUGH THE PERIOD.
A MEDIOCRE SHORTWAVE TROUGH IS EXPECTED TO MOVE EAST ACROSS NORTHERN
AND CENTRAL CANADA BY FRIDAY BUT SHOULD REMAIN NORTH OF THE AREA.
THIS SHOULD KEEP A ZONAL FLOW PATTERN GOING THROUGH THE DURATION.
SURFACE HIGH PRESSURE OVER THE FORECAST AREA WILL MOVE EAST OF THE
REGION AND BE OFF THE ATLANTIC COAST BY FRIDAY. THIS TRANSITION WILL
BRING A RETURN SOUTHERLY FLOW INTO THE FORECAST AREA ALONG WITH MORE
STRONG WARM AIR ADVECTION. MID LEVEL AND SURFACE AIR WILL TRACK
RIGHT UP OUT OF THE PANHANDLE OF OKLAHOMA TOWARD THE END OF THE
WEEK. A COLD FRONT IS PROGGED TO MOVE EAST INTO THE AREA BY FRIDAY
EVENING AND BECOME NEARLY STATIONARY. SOME LIMITED MOISTURE
ASSOCIATED WITH THE FRONT WILL BRING WITH IT THE BEST CHANCE FOR
SHOWERS AND THUNDERSTORMS FRIDAY. SCATTERED AFTERNOON CONVECTION IS
POSSIBLE THE REST OF THE DAYS ON THE WEST SIDE OF THE HIGH PRESSURE
CENTER.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
UPPER LEVEL RIDGE STILL IN PLACE OVER THE FORECAST AREA AT THIS
TIME. A LONE SHOWER MOVED NORTH BUT REMAINED JUST EAST OF THE
TOLEDO AND FINDLAY TAF SITES. EXPECTING A POSSIBILITY FOR SHOWERS
AND THUNDERSTORMS THIS AFTERNOON OVER THE WESTERN PORTIONS OF THE
REGION. LATEST HRRR MODEL IS SHOWING A THREAT FOR AN ISOLATED
SHOWER TO MOVE NORTHEAST ALONG THE LAKE SHORE FROM CLEVELAND TO
ERIE EARLY THIS AFTERNOON. BUT WILL LEAVE THINGS DRY AT ERIE AT
THIS POINT SINCE IT WILL BE SO WIDELY SCATTERED IF IT OCCURS.
OTHERWISE DRY FOR THE REST OF THE TAF SITES. WINDS WILL BE ON THE
INCREASE LATER TONIGHT FROM THE SOUTH AS WELL. EARLIER FORECAST
MENTIONED SOME WIND SHEAR. LATEST GUIDANCE NOW SUGGESTS WINDS WILL
GRADUALLY INCREASE FROM 10 KNOTS AT THE SURFACE TO 40 KNOTS AT
2000 FEET SO NOT EXPECTING WIND SHEAR AT THIS TIME.
OUTLOOK...NON VFR LIKELY IN SHOWERS AND THUNDERSTORMS SATURDAY
THROUGH TUESDAY AT TIMES.
&&
.MARINE...
FAIRLY DESCENT FLOW WILL DEVELOP LATER TONIGHT OUT OF THE SOUTHWEST
AND COULD POSSIBLY BE STRONG ENOUGH TO SUPPORT SMALL CRAFT ADVISORY
CRITERIA FOR A PERIOD OF TIME. EXPECTING WINDS TO DIMINISH ON SUNDAY
TO LIGHT SOUTH TO SOUTHWEST AND THEN INCREASE AGAIN BY MONDAY NIGHT
AHEAD OF THE NEXT COLD FRONT. OTHERWISE...WINDS LOOK FAIRLY LIGHT
GOING INTO WEDNESDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...LOMBARDY
AVIATION...LOMBARDY
MARINE...LOMBARDY
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
648 AM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 437 AM CDT SAT AUG 30 2014
ISOLATED SHOWERS AHEAD OF WEAK NORTHERN STREAM WAVE IN WEST CENTRAL
MN HAVE COME TO AN END ACROSS SW MN EARLY THIS MORNING...AND NOW
WATCHING MASS OF STRATUS SPILLING SOUTHWARD ACROSS THE NORTHERN
PLAINS. THROUGH AT LEAST MIDDAY...THIS STRATUS SHOULD BE QUITE
PERSISTENT OVER MUCH OF THE CWA...ERODING IN THE VICINITY OF THE LOW
LEVEL RIDGE AXIS NEAR THE JAMES VALLEY. CLOUDS MAY BE SOMEWHAT MORE
PERSISTENT EAST...STYMIED BY FAIRLY WEAK FLOW TOWARD I29 AND
SOUTHWEST MINNESOTA...BUT SHOULD SEE A BETTER DECREASING TREND BY
AFTERNOON. THIS WILL IMPACT POTENTIAL HIGHS TODAY...WHICH WILL
LIKELY RANGE FROM MID TO UPPER 70S EAST...TO MID 80S WEST.
HEADING THROUGH THE NIGHT...ENERGY ACROSS THE PACIFIC NORTHWEST WILL
BEGIN TO NUDGE OUT INTO THE NORTHERN PLAINS. FALLING PRESSURES TO
THE WEST WILL INCREASE SOUTHERLY WIND FLOW...ESPECIALLY OFF SURFACE
AS A 40 TO 50 KNOT LOW LEVEL JET DEVELOPS BY LATE EVENING...VEERING
TOWARD THE FSD CWA BY THE FINAL HALF OF THE NIGHT. AIR AT THIS LEVEL
REMAINS FAIRLY DRY...WITH MOISTURE SOURCE COMING MORE ALOFT NEAR OR
ABOVE 700 HPA. ALL PRECIP TONIGHT IS DEPENDENT ON HIGH BASED SHOWERS
AND THUNDERSTORMS DEVELOPING IN WARM AIR ADVECTION ON NOSE OF
STRONGER ELEVATED MIXED LAYER ACTUALLY BEING SIGNIFICANT ENOUGH TO
BREAK THROUGH THE DRIER LAYER BELOW. AS INITIAL PV LOBE LIFTS OUT
ACROSS THE AREA AFTER 06Z...COULD SEE AT LEAST A LOWER COVERAGE OF
PRECIPITATION...BUT CERTAINLY DOES NOT WARRANT MORE THAN A LOW
CHANCE AT THIS POINT WITH THE DEGREE OF DRY AIR AT LOWER
LEVELS...AND WITH BETTER CONVERGENCE OF THE LOW LEVEL JET TO THE
NORTH. SHADED THE HIGHEST CHANCE BY LATER TONIGHT ACROSS THE HIGHWAY
14 CORRIDOR.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 437 AM CDT SAT AUG 30 2014
FOCUS OF THIS FORECAST IS CERTAINLY ON THUNDERSTORM POTENTIAL AND
ASSOCIATED SEVERE WEATHER RISK SUNDAY...DURING THE MIDDLE OF THE
HOLIDAY WEEKEND. NAM SEEMED TO BE AN OUTLIER IN PATTERN TIMING
AND/OR LOCATION, SO HAVE LARGELY FAVORED A GFS/ECMWF BLEND. WITH
THIS...ANTICIPATE ANY EARLY MORNING ELEVATED CONVECTION TO LIFT
NORTH OF THE AREA/DIMINISH THROUGH MID MORNING...WITH PRIMARY
FOCUS THEN SHIFTING TO SOUTHEAST PORTIONS OF THE CWA AS ONE OF
MANY WAVES SLIDES THROUGH THE MID LEVEL TROUGH MOVING INTO THE
NORTHERN PLAINS. LOCATION OF LOW LEVEL BOUNDARIES MAY BE IMPACTED
BY ANY MORNING CONVECTION...BUT ON BROAD SCALE SHOULD SEE COLD
FRONT INTO WESTERN CWA BY MIDDAY...WITH WARM FRONT LOCATION A
LITTLE MORE UNCERTAIN. PREFERRED MODELS POINT TO STRONGEST LOW
LEVEL WARM ADVECTION ALONG 850MB WARM FRONT EXTENDING INTO EASTERN
NEBRASKA AT MIDDAY...THEN LIFTING NORTHWARD INTO NORTHWEST IOWA
WITH THE MID LEVEL WAVE BY LATE AFTERNOON/EVENING. THIS WAVE
ACCOMPANIED BY STRONG DEEP LAYER SHEAR OF 40+KT AND MUCAPE VALUES
IN EXCESS OF 2500J/KG. FORECAST SOUNDINGS SHOW A WEAKENING BUT
STILL EXISTENT CAPPING INVERSION ABOVE 850MB AT KSUX AND OTHER
POINTS IN OUR CWA AT 21Z...BUT THE APPROACHING WAVE SHOULD HELP
OVERCOME THIS...WITH THE CAP ALLOWING FOR MORE DISCRETE INITIAL
CELL DEVELOPMENT IN THE LATE AFTERNOON TO EARLY EVENING. THIS
SHOULD BE TIME OF GREATEST SEVERE POTENTIAL... WITH LARGE
HAIL...DAMAGING WINDS AND ISOLATED TORNADOS ALL POSSIBLE.
THEREAFTER SYSTEM SHOULD CONGEAL INTO PROGRESSIVE CLUSTER OF STORMS
THROUGH THE EVENING...WHICH THEN SHIFTS EAST OF OUR FORECAST AREA BY
EARLY MONDAY MORNING. DUE TO EXPECTED PROGRESSIVENESS OF SYSTEM...DO
NOT ANTICIPATE WIDESPREAD FLOODING THREAT FROM TRAINING STORMS...BUT
ISOLATED MAINLY URBAN FLASH FLOODING POSSIBLE WITH DEEP MOISTURE
PROVIDING POTENTIALLY HEAVY RAINFALL RATES.
LABOR DAY SHOULD BE QUIET AND COOLER WITH HIGHS BACK INTO THE 70S.
ECMWF/GEM BOTH SHOWING ANOTHER WEAK WAVE TRACKING THROUGH THE REGION
AND BRINGING A CHANCE OF STORMS TO THE AREA MONDAY NIGHT.
LONGER RANGE TUESDAY THROUGH FRIDAY LOOKS TO START OFF AS A FAIRLY
QUIET PERIOD...WITH COOLER HIGHS IN THE 70S TUESDAY WARMING BACK
INTO THE 80S WEDNESDAY/THURSDAY. FAIR CONSENSUS BETWEEN THE GFS AND
ECMWF SHOWING AN INCREASED PRECIP POTENTIAL BY THE END OF THE WEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 647 AM CDT SAT AUG 30 2014
IFR TO LIFR CEILINGS WITH STRATUS ENCOMPASSING TAF SITES EARLY
THIS MORNING...AS WELL AS AREAS OF IFR TO MVFR VISIBILITY MAINLY
ACROSS SOUTHWEST MINNESOTA AND NORTHWEST IOWA. WEAKENING LOW LEVEL
FLOW WILL MAKE DECREASE IN STRATUS SOMEWHAT A DIFFICULT PROSPECT...
AND HAVE GONE A BIT SLOWER DECREASE THAN SLOWEST MODEL FOR KFSD...AND
CLOSER TO SLOWER RAP FOR KHON AND KSUX NEARER THE EDGE OF THE FIELD.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...CHAPMAN
LONG TERM...JH
AVIATION...CHAPMAN
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
945 AM EDT SAT AUG 30 2014
.DISCUSSION...PLUME OF MOISTURE STREAMING NORTH FROM THE GULF COAST
REGION THIS MORNING. PRECIPITABLE WATER VALUES CONTINUE TO RISE ON
BOTH OHX AND RNK 12Z SOUNDINGS. EXPECT LIFT TO DEVELOP AHEAD OF THE
APPROACHING UPPER TROUGH THIS AFTERNOON. THE HRRR AND RAP MODELS
SPREAD SHOWERS AND TSRA INTO OUR PLATEAU AND SE TN COUNTIES LATE
THIS AFTERNOON...SO MAY NEED TO GO WITH LIKELY POPS FOR THOSE AREAS.
OTHERWISE...FORECAST GRIDS AND PRODUCTS LOOK ON TRACK.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 89 71 87 71 / 50 50 60 40
KNOXVILLE MCGHEE TYSON AIRPORT, TN 88 71 86 69 / 40 50 60 30
OAK RIDGE, TN 88 71 84 69 / 40 50 60 40
TRI CITIES AIRPORT, TN 89 67 85 65 / 30 50 60 40
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
TG
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
735 AM EDT SAT AUG 30 2014
.SYNOPSIS...
A STALLED FRONT TRAILED FROM SOUTH CAROLINA TO ILLINOIS THIS
MORNING. THIS FRONT WILL MOVE NORTH AND DISSIPATE OVER THE MID
ATLANTIC REGION BY SUNDAY. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
THE GREAT LAKES TONIGHT AND SUNDAY WITH A COLD FRONT TRAILING FROM
THE UPPER MISSISSIPPI VALLEY TO THE CENTRAL PLAINS BY SUNDAY
NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 410 AM EDT SATURDAY...
RADAR SHOWED A NARROW BAND OF SHOWERS FROM ASHE COUNTY NC TO HALIFAX
COUNTY VA. HRRR MOVES THIS PRECIPITATION NORTH THEN HAS IT
DISSIPATING BY 12Z/8AM. IN CONTRAST THE 4KM NAM HAS THE
PRECIPITATION MOVING ALL THE WAY INTO CENTRAL VIRGINIA BY NOON. WILL
LEAN TOWARD THE NAM SOLUTION.
FRONT WAS STATIONARY FROM ILLINOIS TO SOUTH CAROLINA. MODELS TAKE
SURFACE HIGH PRESSURE OFF THE NEW ENGLAND COAST TODAY...ALLOWING THE
BOUNDARY TO MOVE NORTH...BUT EXPECT IT WILL TAKE MUCH OF THE DAY TO
MOVE OUT OF THE COUNTY WARNING AREA. WINDS COMING AROUND TO THE
SOUTH AND ANY CLEARING IN THE AFTERNOON WILL INFLUENCE HOW MUCH
TEMPERATURES WILL RISE TODAY. CLOUD COVER WILL ALSO LIMIT
INSTABILITY TODAY...SO EVEN WITH THE FRONT MOVING THROUGH THE
COVERAGE OF SHOWERS AND THUNDERSTORMS WILL REMAIN ISOLATED TO
SCATTERED. 00Z CANADIAN STARTS BREAKING OUT CLOUD COVER AROUND
14Z/10AM BUT DOES NOT HAVE ALL THE LOW CLOUDS ERODING UNTIL NEARLY
19Z/3PM. WILL STAY CLOSE TO THIS TIMING.
UPPER RIDGE AXIS IS JUST OFF THE SOUTHEAST COAST BY TONIGHT. BROAD
SOUTHWEST FLOW FROM THE LOWER MISSISSIPPI VALLEY TO THE EASTERN GREAT
LAKES TONIGHT. THE SHORT WAVE COMING OUT OF THE NORTHERN GULF AND
THE BEST Q-V FORCING ALONG THE APPROACHING COLD FRONT WILL STILL BE
WEST OF THE FORECAST AREA BY SUNDAY MORNING. MID AND HIGH CLOUDS
WILL COVER THE WESTERN COUNTY WARNING AREA OVERNIGHT...THEN
INCREASING PROBABILITY OF PRECIPITATION IN THE FAR WEST. WITH THE
INCREASING CLOUDS AND SINCE THE FORECAST AREA WILL BE WELL WITHIN
THE WARM SECTOR TONIGHT...NOT MUCH DROP IN TEMPERATURES IS EXPECTED.
USED THE WARMER GUIDANCE FOR OVERNIGHT LOWS.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 310 AM EDT SATURDAY...
A STUBBORN UPPER LEVEL RIDGE WILL HUG THE SOUTHEASTERN COAST LONGER
THAN PREVIOUSLY EXPECTED. FROM A MODEL STAND POINT...THIS UPPER
RIDGE IS ALSO FARTHER INLAND...WHICH WILL LOWER THE CHANCE OF
SHOWERS AND THUNDERSTORMS AS THE SHORT WAVE TRACK IS PUSHED
WESTWARD. THE LATEST 00Z MODELS TRACKS A TROPICAL SHORT WAVE ON THE
OUTER RINGS OF THE RIDGE ACROSS EASTERN TENNESSEE AND CENTRAL
KENTUCKY SUNDAY MORNING...THEN OVER THE OHIO VALLEY IN THE
AFTERNOON. AS THIS SHORT WAVE MOVES OVER THE OHIO VALLEY IN THE
AFTERNOON...MID LEVEL CAPPING WEAKENS ALLOWING STORMS TO GENERATE
ALONG OUT FLOW BOUNDARIES AND IN MODEST INSTABILITIES. WITH THE
STRONGEST LOW LEVEL JET REMAINING OVER THE TENNESSEE AND OHIO
VALLEYS...DISORGANIZED PULSE-LIKE STORMS ARE EXPECTED OVER THE
MOUNTAINS IN THE AFTERNOON AND MAY DRIFT EAST OF THE BLUE RIDGE IN
THE EVENING...IF THE RIDGE DOES JOG TO THE SOUTHEAST. THERE WILL
ALSO BE A LEE TROUGH OVER THE PIEDMONT THAT MAY HELP FIRE STORMS
EAST OF THE BLUE RIDGE DURING THE LATE AFTERNOON AND EVENING HOURS.
CAN NOT RULE OUT THE CHANCE FOR A FEW STORMS TO BECOME SEVERE WHERE
THE CAP IS THE WEAKEST...MOUNTAIN EMPIRE TO THE BLUEFIELD RICHLANDS
AREA. SINCE THE MODELS HAVE MOVED ORGANIZED CONVECTION TO THE
WEST...LOWERED POPS ESPECIALLY IN THE EAST. SINCE THE CHANCES OF
SHOWERS IS LOWER AND SCATTERED IN NATURE...INCREASE TEMPERATURES
ACROSS THE MOUNTAINS INTO THE MID 80S AND U80S-L90S EAST OF THE BLUE
RIDGE.
ON MONDAY...MODELS ONCE AGAIN DRIFT UPPER LEVEL RIDGE TO THE
SOUTH...PLACING THE OUTER RINGS ACROSS THE FORECAST AREA. A WEAK
SHORT WAVE IS EXPECTED TO TRACK ALONG THE SOUTHERN APPALACHIANS
BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS TO THE AREA MONDAY.
ONCE THIS SHORT WAVES TRACKS NORTH OF THE AREA...POSSIBLY BY EARLY
AFTERNOON...SURFACE HIGH PRESSURE WILL BUILD ACROSS THE REGION
MONDAY NIGHT. WITH THE AREA REMAINING IN A MUGGY AIR MASS...PATCHY
DENSE FOG IS LIKELY FOR MOUNTAIN VALLEYS. IF SHOWERS ARE PRIMARILY
DURING THE MORNING...MONDAY AFTERNOON TEMPERATURES WILL WARM INTO
THE MID 80S IN THE WEST TO U80S-L90S EAST OF THE BLUE RIDGE.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 330 PM FRIDAY...
FLAT UPPER RIDGE IS EXPECTED TO DOMINATE OUR MID-WEEK WEATHER
PATTERN ACROSS THE CENTRAL APPALACHIAN AND MID-ATLANTIC REGION. THIS
SHOULD MAINTAIN SUMMER-LIKE TEMPERATURES THROUGH THE ENTIRE PERIOD
WITH HIGHS NEAR 90F IN THE PIEDMONT AND MID-80S IN THE MOUNTAINS
ALONG WITH NIGHT-TIME LOWS IN THE 60S TO LOW 70S. COULD END UP BEING
ONE OF THE WARMEST WEEKS OF THE SUMMER EVEN AS THE SO-CALLED
METEOROLOGICAL SUMMER ENDS ON AUGUST 31. PRECIPITATION WILL ALSO
GENERALLY BE OF SUMMER-LIKE CHARACTER WITH DIURNALLY DRIVEN
CONVECTION PROVIDING THE BEST CHANCES FOR RAINFALL. WEDNESDAY
AFTERNOON LOOKS LIKE THE MOST PROMISING DAY FOR STORMS AS WEAK
FRONTAL BOUNDARY PUSHES ACROSS THE CWA. THURSDAY AND FRIDAY LIKELY
TO BE DRIER ALTHOUGH WIDELY SCATTERED SHOWERS STILL POSSIBLE.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 730 AM EDT SATURDAY...
BROAD AREA OF STRATUS HAD SPREAD WEST ACROSS THE REGION. THE
WESTERN EDGE WAS CLOSE TO KLWB AND KBLF...WITH A SMALL WHOLE THAT
JUST CLOSED RIGHT OVER THE KROA AIRPORT. KBLF AND KLWB SHUD
WILL MAINTAIN VFR CLOUDS.
FOR KBCB/KROA/KDAN AND KLYH IMPROVEMENT IN CEILINGS WILL BE SLOW
THIS MORNING AS A WEAK FRONT LIFTS NORTH THROUGH THE AREA. ONLY
MEDIUM CONFIDENCE AS TO WHEN CEILINGS WILL FINALLY GET BACK TO
VFR. THE THREAT OF SHOWERS AND THUNDERSTORMS THROUGH THE TAF
PERIOD REMAINS LOW ENOUGH TO KEEP OUT OF THE FORECAST FOR NOW.
EXPECT CLOUD COVER TO BE TOO EXTENSIVE TONIGHT FOR FOG
FORMATION...ESPECIALLY IN THE MOUNTAINS. MODELS SUGGESTED THAT LOW
CLOUDS...WITH IFR CEILINGS...MAY REFORM IN THE PIEDMONT. THIS
WOULD MOST LIKELY IMPACT KLYH AND KDAN VERY LATE IN THE TAF
FORECAST PERIOD. CONFIDENCE TOO LOW AT THIS TIME TO INCLUDE IN
THE FORECAST.
EXTENDED DISCUSSION...
ANY ISOLATED OR SCATTERED SHOWERS AND STORMS WILL BE MAINLY
ALONG AND NORTH OF A KHSP-KFVX LINE THIS EVENING...JUST SOUTH OF
THE AGAIN STALLED FRONTAL BOUNDARY.
LATE TONIGHT THROUGH SUNDAY EVENING AN AREA OF LOW PRESSURE WILL
HEAD EASTWARD THROUGH THE GREAT LAKES REGION TOWARD NEW ENGLAND.
ITS ASSOCIATED COLD FRONT WILL SWEEP THROUGH THE REGION BRINGING A
GENEROUS COVERAGE OF SHOWERS AND SOME STORMS. SUB-VFR CONDITIONS
ARE EXPECTED TO ACCOMPANY THE SYSTEM AND PRECIPITATION.
ANOTHER COLD FRONT IS EXPECTED TO PRODUCE SIMILAR CONDITIONS TUESDAY
INTO WEDNESDAY. HOWEVER...MODEL GUIDANCE FOR THIS ONE OFFERS
PRECIPITATION IN A MORE SCATTERED DISTRIBUTION. AS SUCH...THE
MAGNITUDE OF SUB-VFR CONDITIONS MAY BE LESS.
&&
.EQUIPMENT...
AS OF 730 AM EDT FRIDAY ...
THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WILL
BE OUT OF SERVICE UNTIL FURTHER NOTICE. A PART HAS BEEN BACK-ORDERED.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...RCS
LONG TERM...PC
AVIATION...AMS/JH
EQUIPMENT...AMS
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1030 AM CDT SAT AUG 30 2014
.UPDATE...RAP/WATER VAPOR ANIMATION SHOW SHORT WAVE AND ASSOCIATED
SPEED MAX LIFTING NORTHEAST. NMRS SHRA ACRS SRN WI. MES MODELS
SHOW THIS ACTIVITY LINGERING INTO THE AFTN. SECONDARY SHORTWAVE
DROPPING SEWD FROM MN NOT LIKELY TO HAVE MUCH HEATING TO WORK WITH
AS LOW CLOUD COVER WIDESPREAD. NEVERTHELESS STILL EXPECT SOME SHRA
ACTIVITY TO DOMINATE THIS AFTERNOON WITH LOW LEVEL TROUGH AXIS IN
VCNTY AND UPPER CYCLONIC FLOW PERSISTING.
PC
&&
.AVIATION/18Z TAFS/...PLENTY OF MVFR CIGS TO CONTEND WITH INTO THE
AFTN AND LIKELY THE ERLY EVE AS WELL. BROAD CYCLONIC FLOW ALONG
WITH EMBEDDED SHORTWAVES. SURFACE/850 TROUGH AXIS ALSO IN THE
VICINITY WITH ABUNDANT LOW LEVEL MOISTURE. ANY HOLES IN THE OVC
ACRS ERN MN AND NE IA FILLING RIGHT BACK IN. LOW CLOUD COVER
GRADUALLY OVERSPREADING FAR ERN WI THOUGH SLOWER TO INCREASE
THERE. WITH SOME DIURNAL DISSIPATION TO THIS CLOUD COVER...FOG
DEVELOPMENT STILL SEEMS ON TRACK WITH THE LOW LEVEL MOISTURE AND
LIGHT WIND REGIME.
PC
&&
.PREV DISCUSSION... /ISSUED 319 AM CDT SAT AUG 30 2014/
TODAY...FORECAST CONFIDENCE IS MEDIUM.
A WELL DEFINED MID LEVEL SHORT WAVE OVER CENTRAL IOWA EARLY THIS
MORNING WILL LIFT NORTHEAST AND TRACK TO NEAR GREEN BAY BY EARLY
THIS AFTERNOON. THE ASSOCIATED SURFACE LOW WILL TAKE A SIMILAR PATH.
THE FIRST ROUND OF SHOWERS AND STORMS IS EXITING TO THE NORTH OF THE
FORECAST AREA EARLY THIS MORNING. THIS STUFF WAS GENERALLY
ASSOCIATED WITH A FAVORABLE COMBINATION OF A LOW LEVEL JET AND SOME
UPPER LEVEL DIVERGENCE FROM THE RIGHT ENTRANCE REGION OF UPPER JET.
A SECOND ROUND SHOULD LIFT UP HERE BETWEEN 09-13Z THIS
MORNING...MORE DIRECTLY TIED TO THE CIRCULATION OF THE MID LEVEL
SHORT WAVE. THE HRRR DOESN/T DO MUCH WITH THIS SECOND ROUND...IN
FACT WEAKENING IT AS IT GETS UP HERE. WILL TRY TO REFINE THE TIMING
OF POPS AND COVERAGE TO MATCH THESE TRENDS. THE AFTERNOON COULD
FEATURE SCATTERED DIURNAL SHOWERS AND A POSSIBLE THUNDERSTORM AS THE
UPPER TROF AXIS MOVES THROUGH. THE SHOWERS/STORMS ARE MOVING
QUICKLY...SO DESPITE THE HIGH MOISTURE CONTENT OF THE
COLUMN...FLOODING CONCERNS ARE NIL. HIGHS WILL BE IN THE 70S WITH
DEWPOINTS REMAINING HIGH...SO IT WILL FEEL MUGGY OUT THERE.
TONIGHT...FORECAST CONFIDENCE IS MEDIUM.
SOME OF THE MODELS ARE DEPICTING SOME SHOWERS INTO THE EVENING WITH
A SECONDARY SHORT WAVE EXITING...BUT THE COLUMN IS DRYING OUT AND
THE BEST FORCING MOVES EAST. SO AT THIS POINT...WILL CONTINUE THE
DRY FORECAST. STILL HUMID WITH ELEVATED DEWPOINTS OVERNIGHT. THE
PATTERN TURNS RATHER BAGGY WITH LIGHT TO CALM WINDS...SO WILL THROW
IN SOME PATCHY FOG AFTER MIDNIGHT.
SUNDAY AND MONDAY...FORECAST CONFIDENCE...MEDIUM
SUNDAY LOOKS LIKE A PLEASANT DAY WITH A FAIR AMOUNT OF SUNSHINE.
MODELS ARE SHOWING A WEAK WAVE PASSING THROUGH...BUT MODELS ARE
SHOWING A GOOD AMOUNT OF DRY AIR IN THE MID AND UPPER LEVELS...SO
KEPT THE FORECAST DRY. HIGH TEMPS SHOULD BE A FEW DEGREES ABOVE
NORMAL.
SHOWERS AND STORMS ARE LIKELY IN THE WEST BY DAYBREAK MONDAY
MORNING AND THEN ACROSS THE FORECAST AREA DURING THE DAY AS A
COLD FRONT MOVES THROUGH. SOME STRONG TO SEVERE STORMS ARE
POSSIBLE...BUT THIS WILL BE DEPENDENT ON THE TIMING OF THE FRONT.
IT LOOKS LIKE A DECENT AMOUNT OF INSTABILITY TO GO ALONG WITH
AROUND 45 KNOTS OF 0-6 KM BULK SHEAR. SPC DAY 3 CONVECTIVE
OUTLOOK HAS THE SOUTHERN FORECAST AREA IN A SLIGHT RISK FOR
SEVERE STORMS.
TUESDAY THROUGH FRIDAY...FORECAST CONFIDENCE...MEDIUM
IT LOOKS MAINLY DRY TUESDAY AND WEDNESDAY AS SURFACE HIGH PRESSURE
SLIDES THROUGH THE AREA. A COUPLE MODELS ARE SHOWING A WEAK WAVE
OR TWO BRINGING SOME SPLOTCHY QPF HERE AND THERE...BUT NOT SEEING
A CONSISTENT SIGNAL AT THIS POINT SO KEPT THE FORECAST DRY.
A RETURN OF MOISTURE UNDER SOUTHERLY LOW LEVEL FLOW IS EXPECTED TO
BRING A CHANCE FOR SHOWERS AND STORMS BACK TO THE AREA THURSDAY
AND FRIDAY.
TEMPERATURES FOR THE TUESDAY THROUGH FRIDAY TIME PERIOD SHOULD
REMAIN NEAR TO A COUPLE DEGREES ABOVE NORMAL.
AVIATION/12Z TAFS/...MVFR TO IFR CIGS SHOULD OVERSPREAD SOUTHERN
WISCONSIN EARLY THIS MORNING...THEN GRADUALLY IMPROVE TO VFR THIS
AFTERNOON AS LOW PRESSURE PASSES BY TO THE NORTH. MOSTLY PLACES
SHOULD BE VFR BY 19-20Z. DRIER AIR SHOULD EVENTUALLY WORK IN ON
INCREASING SOUTHWEST THEN WESTERLY WINDS. WINDS BECOME LIGHT
TONIGHT AND WITH LINGERING HIGH DEWPOINTS...WE MAY SEE SOME PATCHY
FOG AFTER MIDNIGHT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...DAVIS
SUNDAY THROUGH FRIDAY...DDV
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
646 AM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 321 AM CDT SAT AUG 30 2014
MAIN FORECAST CONCERN IS WITH THE RAIN CHANCES TODAY AND FROM
SUNDAY NIGHT INTO MONDAY.
LOCAL AND REGIONAL RADARS SHOWING A LARGE AREA OF RAIN LIFTING
NORTHEAST ACROSS EASTERN MINNESOTA AND MUCH OF WISCONSIN. SOME
TRAILING RAIN STILL BACK ACROSS EASTERN IOWA.
EXPECT THE RAIN TO CONTINUE LIFTING NORTHEAST THIS MORNING AS THE
SURFACE LOW JUST ENTERING WESTERN WISCONSIN ALSO CONTINUES TO MOVE
NORTHEAST IN CONJUNCTION WITH THE UPPER LEVEL TROUGH. THE 30.04Z
HRRR SEEMS TO HAVE A DECENT HANDLE ON THE ONGOING RAIN AND SHOWS
THE BACK EDGE ALONG THE MISSISSIPPI RIVER BY 12Z WITH MOST OF THE
AREA DRY BY 18Z. THIS IS VERY SIMILAR TO WHAT THE 30.00Z HI-RES
ARW AND NMM SHOW AND WILL PLAN TO TREND THE RAIN CHANCES IN THIS
DIRECTION. THE QUESTION THEN BECOMES IF ADDITIONAL ACTIVITY WILL
DEVELOP THIS AFTERNOON. THE 30.00Z NAM AND GFS BOTH BRING A
TRAILING SHORT WAVE TROUGH ACROSS THE AREA THIS AFTERNOON. IT DOES
APPEAR IN THE WATER VAPOR IMAGERY THAT THIS WAVE DOES EXIST AND IS
OVER EASTERN SOUTH DAKOTA. HOWEVER...THE WATER VAPOR IMAGERY ALSO
SHOWS A LOT OF DRY AIR IN PLACE BEHIND THE DEPARTING SHORT WAVE
TROUGH AND THE CONCERN BECOMES WHETHER THIS SECONDARY SHORT WAVE
TROUGH WILL HAVE ENOUGH FORCING TO CAUSE SOME ADDITIONAL
DEVELOPMENT. THE HRRR IS SUGGESTING THAT SOME COULD START TO FORM
EARLY IN THE AFTERNOON WHICH IS SIMILAR TO THE NAM AND GFS WHILE
THE ARW AND NMM REMAIN DRY THROUGH THE AFTERNOON. WITH ALL THE DRY
AIR...TEND TO FEEL THE ARW AND NMM HAVE THE MORE CORRECT SOLUTION
BUT WILL HOLD ONTO A SMALL RAIN CHANCE JUST IN CASE SOMETHING DOES
POP UP.
AFTER SOME WEAK UPPER LEVEL RIDGING MOVES OVER THE UPPER MIDWEST
TONIGHT AND SUNDAY...THE NEXT SYSTEM WILL TAKE AIM AT THE REGION.
WATER VAPOR IMAGERY ALREADY SHOWS IT APPROACHING THE PACIFIC
NORTHWEST COAST AND IT IS EXPECTED TO MOVE QUICKLY ACROSS THE
NORTHERN ROCKIES AND ACROSS THE UPPER MIDWEST SUNDAY NIGHT AND
MONDAY. THE GFS AND 30.00Z ECMWF BOTH CONTINUE TO SHOW THIS SYSTEM
PRODUCING MODERATE TO STRONG PV ADVECTION IN THE 500-300 MB LAYER
LATE SUNDAY NIGHT INTO MONDAY MORNING. THE GFS SHOWS STRONG
ISENTROPIC UP GLIDE SHOULD SPREAD ACROSS THE AREA SUNDAY NIGHT
AHEAD OF THE SHORT WAVE TROUGH WITH UP TO 10 UBAR/S ON THE 305K
SURFACE. THE NOSE OF THE LOW LEVEL JET IS EXPECTED TO BECOME
ORIENTED INTO THE AREA SUNDAY EVENING WITH LITTLE MOVEMENT SUNDAY
NIGHT BEFORE VEERING OFF TO THE EAST MONDAY MORNING. WITH THE
AMPLE FORCING...WIDESPREAD SHOWERS AND STORMS ARE EXPECTED TO MOVE
IN SUNDAY EVENING AND WORK EAST ACROSS THE AREA BEFORE ENDING
MONDAY AFTERNOON. GOOD CAPE WILL BUILD SUNDAY AFTERNOON WEST OF
THE AREA AHEAD OF THE COLD FRONT ASSOCIATED WITH THIS SYSTEM. THE
GFS SUGGESTS THAT AN AXIS OF 1000-1500 J/KG OF ML CAPE WILL
PERSIST AHEAD OF THE FRONT THROUGH THE NIGHT AS THE SYSTEM WORKS
ACROSS THE AREA. GOOD SHEAR LOOKS TO OVERSPREAD THE REGION WITH 40
TO 50 KNOTS OF 0-6KM SHEAR...BUT MOST OF THIS LOOKS TO BE IN THE
0-3KM LAYER WITH 35 TO 40 KNOTS. EXPECT THAT THIS WILL BE
SUFFICIENT TO SUPPORT SOME STRONG TO SEVERE STORMS WITH HAIL AND
WIND THE MAIN THREATS.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 321 AM CDT SAT AUG 30 2014
SOME SMALL RAIN CHANCES WILL CONTINUE INTO TUESDAY AS A SECONDARY
SHORT WAVE TROUGH LOOKS TO SWEEP ACROSS THE UPPER MIDWEST.
AGAIN...THERE SHOULD BE GOOD DRYING SO THE QUESTION BECOMES IF THE
FORCING WILL BE ENOUGH TO GENERATE SOME ACTIVITY. AFTER
THAT...RIDGING LOOKS TO BUILD OVER THE REGION FOR A SHORT PERIOD
WEDNESDAY AND WEDNESDAY NIGHT. THE FLOW THEN SHOULD BECOME
SOUTHWEST ALLOWING A POSITIVE TILT LONG WAVE TROUGH TO APPROACH
FROM THE NORTHWEST. DIFFERENCES BETWEEN THE ECMWF AND GFS ON HOW
FAST THIS TROUGH MOVES THROUGH WITH THE ECMWF CONSIDERABLY FASTER.
WILL HAVE SOME RAIN CHANCES WITH THIS SYSTEM BUT WILL UNDERCUT THE
MODEL CONSENSUS GRIDS SOME THINKING THE RIDGE WILL BE THE DOMINANT
FEATURE THROUGH THE END OF THE PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 646 AM CDT SAT AUG 30 2014
LOW PRESSURE OVER CENTRAL WISCONSIN WILL CONTINUE MOVING NORTHEAST
OUT OF THE AREA TODAY. LOOK FOR SCATTERED -SHRA ACTIVITY TO
CONTINUE AT THE KRST/KLSE TAF SITES EARLY ON THIS MORNING...THEN
MOVING OUT BY 14-15Z. OTHERWISE...THERE WILL BE SOME IFR/MVFR CLOUD
COVER TO DEAL WITH IN THE WAKE OF THE LOW. LOOK FOR THE CEILINGS
TO RISE TO VFR BY LATER THIS AFTERNOON WITH DAYTIME HEATING. HIGH
PRESSURE WILL THEN SLIDE ACROSS THE AREA TONIGHT FOR SOME
CLEARING. DUE TO THE RECENT RAINFALL AND VERY MOIST LOWER BOUNDARY
LAYER...AREAS OF FOG ARE LIKELY. FOR NOW...WENT WITH 3-5SM BR AT
KRST/KLSE ALONG WITH SCATTERED STRATUS. THIS WILL HAVE TO BE
WATCHED CLOSELY FOR POSSIBLE FULL-ON IFR/LIFR CONDITIONS.
&&
.HYDROLOGY...
ISSUED AT 321 AM CDT SAT AUG 30 2014
ADDITIONAL RAINFALL TODAY WILL BE A QUARTER INCH OR LESS AND THIS
WILL NOT BE ENOUGH TO CAUSE ANY FLOODING PROBLEMS. WITH THE SYSTEM
THAT WILL AFFECT THE AREA SUNDAY NIGHT AND MONDAY...CURRENT
EXPECTATIONS ARE THAT THE RAIN TOTALS WILL BE AN INCH OR LESS. THE
PRECIPITABLE WATER IS NOT EXPECTED TO BE QUITE AS HIGH WITH THE
GFS SHOWING AROUND 1.75 INCHES BUT WARM CLOUD DEPTHS WILL STILL BE
IN THE 3.5 TO 4 KM RANGE. THE SHOWERS AND STORMS WILL HAVE THE
POTENTIAL TO PRODUCE SOME HIGHER RAIN RATES...BUT WITH THE
CONVECTION EXPECTED TO BE PROGRESSIVE...IT SHOULD NOT POSE ANY
LARGE SCALE FLOODING PROBLEMS AND PLAN TO ISSUE THE LAST ESF THIS
MORNING STATING THIS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...DAS
HYDROLOGY...04
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
513 PM CDT SAT AUG 30 2014
.DISCUSSION...
221 PM CDT
SYNOPSIS...SCATTERED THUNDERSTORMS ARE POSSIBLE NW OF I-55 WHILE A
LINE OF STORMS WILL IMPACT AREAS ALONG AND EAST OF I-55 THROUGH THIS
EVENING. TOMORROW WILL BE DRY BUT UNSETTLED WEATHER RETURNS MONDAY
WITH MULTIPLE CHANCES FOR THUNDERSTORMS. SEVERE STORMS ARE POSSIBLE
MONDAY. TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE PERIOD WITH A
COUPLE DAYS GETTING INTO THE MID 80S.
THROUGH TONIGHT...
AN UPPER LEVEL TROUGH IS OVER THE UPPER MISSISSIPPI RIVER VALLEY AND
IT WILL PASS OVER THE REGION THROUGH THIS EVENING. A SURFACE LOW IS
OVER THE NORTHERN END OF LAKE MI WITH ITS COLD FRONT EXTENDING
THROUGH WI AND EASTERN IA. THE LOW WILL CONTINUE NE THROUGH THE
NIGHT.
HAVE MUCH HIGHER CONFIDENCE IN THE CONVECTIVE FORECAST TODAY
COMPARED TO YESTERDAY DUE TO CLEAR FORCING MECHANISMS. EXPECTING TO
HAVE TWO AREAS TO MONITOR. THE FIRST IS NORTHWEST OF I-55 WHERE
ISOLATED TO SCATTERED STORMS WILL CONTINUE TO FESTER THROUGH THIS
AFTERNOON AHEAD OF UPPER LEVEL WAVE AND COLD FRONT.
THE BIGGER CONCERN WILL BE ALONG AND SE OF I-55 WHERE A LINE OF
SHOWERS AND STORMS HAS ALREADY DEVELOPED. THE LATEST RAP ANALYSIS
SHOWS A NICE CORRIDOR OF MOISTURE CONVERGENCE WHERE THE CONVECTION
HAS FIRED. THE LATEST AMDAR SOUNDINGS ARE CAPLESS WITH 1000-1500
J/KG OF CAPE. HOWEVER...LAPSE RATES ARE POOR AND WIND SHEAR IS
MINIMAL AT BEST. THE AMDAR SOUNDINGS DO HAVE LOW LEVEL INVERTED
V/S AND THE RAP ANALYSIS HAS AROUND 1000 J/KG OF DOWNDRAFT CAPE.
THEREFORE NOT EXPECTING WIDESPREAD SEVERE WEATHER...BUT A STORM OR
TWO MAY PULSE UP AND PRODUCE SEVERE WINDS.
HEAVY DOWNPOURS ARE ALSO EXPECTED WITH PWAT VALUES OF 1.6-1.8
INCHES. BASED ON SHORT TERM GUIDANCE...THE AREA MOST CONCERNING IS
SOUTH OF A VALPARAISO IN TO GIBSON CITY IL LINE. STORMS WILL
CONTINUE TO DEVELOP AND MOVE OVER THIS REGION WITH AMPLE FORCING.
THEREFORE IF STORMS TRAIN OVER THE SAME AREA FOR AN EXTENDED PERIOD
OF TIME...FLASH FLOODING MAY OCCUR.
STORMS DIMINISH AND PUSH EAST OVERNIGHT WHILE HIGH PRESSURE SPREADS
OVER THE REGION. WINDS WILL DIMINISH AND FOG IS POSSIBLE.
SUNDAY...
SUNDAY LOOKS DRY WITH HIGH PRESSURE OVER THE REGION. WE WILL BE IN
THE NEXT LOW/S WARM SECTOR WITH 850MB TEMPS AROUND 18C. THEREFORE
RAISED HIGH TEMPS INTO THE MID 80S AWAY FROM THE LAKE. THE WEAK
PRESSURE GRADIENT WILL ALLOW A LAKE BREEZE TO FORM AND KEEP THE IL
LAKEFRONT AROUND 80. GUIDANCE HAS SLOWED THE NEXT LOW SO PUSHED
BACK POPS SUNDAY NIGHT.
JEE
MONDAY...
UPPER WAVE DIGGING TOWARDS THE INTERMOUNTAIN WEST THIS AFTERNOON
WILL LIFT ACROSS THE PLAINS INTO THE UPPER MIDWEST ON MONDAY WITH
ATTENDANT SURFACE LOW DEEPENING AS IT LIFTS ACROSS ONTARIO TO NEAR
JAMES BAY BY LATE MONDAY. A SURFACE FRONT WILL SLOWLY PUSH ACROSS
THE REGION MONDAY AND GUIDANCE HAS TRENDED TOWARDS A SLOWER SOLUTION
OVER THE LAST 24 HOURS. MODERATE TO STRONG INSTABILITY IS PROGGED TO
DEVELOP ALONG AND AHEAD OF THE FRONT WHERE THE GFS ADVERTISES A
CORRIDOR OF JUST OVER 2000 J/KG MLCAPE JUST TO THE WEST OF THE CWA
MONDAY AFTERNOON. THE BETTER CONVERGENCE ASSOCIATED WITH THE COLD
FRONT MAY ARRIVE JUST PAST THE MOST FAVORABLE DIURNAL TIMING IF
TIMING TRENDS HOLD TRUE...BUT THE RIGHT ENTRANCE REGION TO THE UPPER
JET IS PROGGED TO MOVE OVER THE AREA BY MID TO LATE IN THE EVENING
WITH DEEP LAYER SHEAR VALUES INCREASING TO AROUND 40 KT OR SO WHICH
WOULD BE SUFFICIENT FOR AN ORGANIZED SEVERE WEATHER THREAT...THOUGH
THIS THREAT SHOULD DIMINISH WEST TO EAST AS WE GET LATER INTO THE
OVERNIGHT HOURS AND THE BOUNDARY LAYER STABILIZES.
TUESDAY THROUGH THURSDAY...
A SECONDARY SHORTWAVE TROUGH IS PROGGED TO PUSH ACROSS THE REGION ON
TUESDAY BRINGING ADDITIONAL CHANCES FOR SHOWER AND THUNDERSTORMS
MAINLY ACROSS SOUTH/SOUTHEASTERN PORTIONS OF THE CWA WHERE THE
FRONTAL BOUNDARY MAY STILL SLOWLY BE MAKING A PUSH. MODERATE TO
STRONG HEIGHTS RISES QUICKLY BUILD IN BEHIND THIS FEATURE THOUGH AND
SHOULD RESULT IN A DRY WEATHER FOR MOST OF THE FORECAST AREA
TUESDAY. THE GFS IS PARTICULAR IS HOLDING ONTO SOME POPS NORTH OF
THE BOUNDARY WEDNESDAY INTO THURSDAY WHERE PERSISTENT WARM ADVECTION
WILL RESULT IN MID LEVEL ASCENT...THOUGH THE ECMWF REMAINS DRY THIS
PERIOD. WILL MAINTAIN SLIGHT CHANCE POPS IN THE MEANTIME.
FRIDAY THROUGH SATURDAY...
THERMAL RIDGE IS EXPECTED TO MOVE BACK OVERHEAD LATE IN THE WEEK
WITH H85 TEMPS PUSHING INTO THE LOW 20C RANGE WHICH WILL LEAD TO
ANOTHER WARMUP WITH TEMPS INTO THE UPPER 80S. ANOTHER SLOW MOVING
COLD FRONT WILL THEN SAG SOUTH ACROSS THE REGION BRINGING RENEWED
CHANCES FOR SHOWERS AND THUNDERSTORMS.
DEUBELBEISS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* GUSTY WEST-SOUTHWEST WINDS DIMINISHING EARLY THIS EVENING.
* IFR CIGS AND VSBYS POSSIBLE OVERNIGHT INTO EARLY SUNDAY.
LENNING/IZZI
//DISCUSSION...UPDATED 18Z...
MODEL FORECAST DATA...SATELLITE IMAGERY...ACARS AIRCRAFT
SOUNDINGS...AND RECENT RADAR TRENDS ALL SUPPORT THE IDEA OF
INCREASED CONVECTIVE DEVELOPMENT THIS AFTERNOON...PRIMARILY
FOCUSED SOUTHEAST OF THE ORD/MDW TERMINALS. SO FAR THIS MORNING
INTO EARLY AFTERNOON THERE HAS BEEN LITTLE LIGHTNING WITH THE FEW
CELLS THAT HAVE DEVELOPED...BUT WOULD NOT BE SURPRISED TO SEE MORE
ACTIVE CONVECTION AS WE APPROACH PEAK DIURNAL HEATING. LESS
PRONOUNCED MOISTURE TRANSPORT NORTHWEST OF THIS CORRIDOR ALONG
WITH RELATIVELY WARM AIR ALOFT ARE THE FACTORS CONTRIBUTING TO
LESS CONFIDENCE OF WIDESPREAD AFTERNOON CONVECTION ACROSS THE
NORTHWEST HALF OF THE AREA...INCLUDING ORD/MDW AS WELL AS DPA AND
RFD. THE GYY TERMINAL WOULD BE ALONG THE NORTHWEST EDGE OF THE
AREA EXPECTED TO HAVE THE MORE EXTENSIVE COVERAGE.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* LOW-MEDIUM CONFIDENCE OF IFR CIGS AND VSBYS OVERNIGHT.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS.
IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...VFR.
MONDAY...PERIODS OF TSRA LIKELY.
TUESDAY...SLIGHT CHANCE TSRA EARLY.
WEDNESDAY...SLIGHT CHANCE TSRA OVERNIGHT.
THURSDAY AND FRIDAY...CHANCE TSRA.
KREIN
&&
.MARINE...
221 PM CDT
MODERATE SOUTHWEST FLOW IS CURRENTLY IN PLACE ACROSS LAKE MICHIGAN
WHERE SOUTHWEST WINDS ARE GUSTING 20 TO 25 KTS WITH OCCASIONAL 30 KT
WINDS. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE NEARSHORE
WATERS THROUGH LATE THIS EVENING. THIS IS AHEAD OF LOW PRESSURE
CURRENTLY CENTERED NEAR GREEN BAY. THE LOW WILL DRAG A COLD FRONT
SOUTH ACROSS LAKE MICHIGAN TONIGHT TURNING WINDS TO THE NORTHWEST.
WINDS WILL ABATE BRIEFLY AS TRANSIENT HIGH PRESSURE PUSHES ACROSS
THE NORTHERN LAKES REGION...BUT BY MIDDAY SUNDAY WINDS ARE EXPECTED
TO BEGIN TO TURN SOUTHEAST AND START TO RAMP UP AGAIN AHEAD OF
ANOTHER AREA OF LOW PRESSURE. THIS NEXT WILL LOW LIFT FROM THE
NORTHERN PLAINS...DEEPENING AS IT HEADS TO HUDSON BAY MONDAY NIGHT
INTO TUESDAY. SOUTH WINDS ARE EXPECTED TO PEAK MONDAY OVER THE LAKE
WITH GUSTS SOLIDLY INTO THE 20 KT RANGE...APPROACHING 30 KT OVER THE
NORTH END OF THE LAKE. ANOTHER COLD FRONT WILL SAG SOUTH ACROSS LAKE
MICHIGAN MONDAY NIGHT.
DEUBELBEISS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 11 PM SATURDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
252 PM CDT SAT AUG 30 2014
.DISCUSSION...
221 PM CDT
SYNOPSIS...SCATTERED THUNDERSTORMS ARE POSSIBLE NW OF I-55 WHILE A
LINE OF STORMS WILL IMPACT AREAS ALONG AND EAST OF I-55 THROUGH THIS
EVENING. TOMORROW WILL BE DRY BUT UNSETTLED WEATHER RETURNS MONDAY
WITH MULTIPLE CHANCES FOR THUNDERSTORMS. SEVERE STORMS ARE POSSIBLE
MONDAY. TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE PERIOD WITH A
COUPLE DAYS GETTING INTO THE MID 80S.
THROUGH TONIGHT...
AN UPPER LEVEL TROUGH IS OVER THE UPPER MISSISSIPPI RIVER VALLEY AND
IT WILL PASS OVER THE REGION THROUGH THIS EVENING. A SURFACE LOW IS
OVER THE NORTHERN END OF LAKE MI WITH ITS COLD FRONT EXTENDING
THROUGH WI AND EASTERN IA. THE LOW WILL CONTINUE NE THROUGH THE
NIGHT.
HAVE MUCH HIGHER CONFIDENCE IN THE CONVECTIVE FORECAST TODAY
COMPARED TO YESTERDAY DUE TO CLEAR FORCING MECHANISMS. EXPECTING TO
HAVE TWO AREAS TO MONITOR. THE FIRST IS NORTHWEST OF I-55 WHERE
ISOLATED TO SCATTERED STORMS WILL CONTINUE TO FESTER THROUGH THIS
AFTERNOON AHEAD OF UPPER LEVEL WAVE AND COLD FRONT.
THE BIGGER CONCERN WILL BE ALONG AND SE OF I-55 WHERE A LINE OF
SHOWERS AND STORMS HAS ALREADY DEVELOPED. THE LATEST RAP ANALYSIS
SHOWS A NICE CORRIDOR OF MOISTURE CONVERGENCE WHERE THE CONVECTION
HAS FIRED. THE LATEST AMDAR SOUNDINGS ARE CAPLESS WITH 1000-1500
J/KG OF CAPE. HOWEVER...LAPSE RATES ARE POOR AND WIND SHEAR IS
MINIMAL AT BEST. THE AMDAR SOUNDINGS DO HAVE LOW LEVEL INVERTED
V/S AND THE RAP ANALYSIS HAS AROUND 1000 J/KG OF DOWNDRAFT CAPE.
THEREFORE NOT EXPECTING WIDESPREAD SEVERE WEATHER...BUT A STORM OR
TWO MAY PULSE UP AND PRODUCE SEVERE WINDS.
HEAVY DOWNPOURS ARE ALSO EXPECTED WITH PWAT VALUES OF 1.6-1.8
INCHES. BASED ON SHORT TERM GUIDANCE...THE AREA MOST CONCERNING IS
SOUTH OF A VALPARAISO IN TO GIBSON CITY IL LINE. STORMS WILL
CONTINUE TO DEVELOP AND MOVE OVER THIS REGION WITH AMPLE FORCING.
THEREFORE IF STORMS TRAIN OVER THE SAME AREA FOR AN EXTENDED PERIOD
OF TIME...FLASH FLOODING MAY OCCUR.
STORMS DIMINISH AND PUSH EAST OVERNIGHT WHILE HIGH PRESSURE SPREADS
OVER THE REGION. WINDS WILL DIMINISH AND FOG IS POSSIBLE.
SUNDAY...
SUNDAY LOOKS DRY WITH HIGH PRESSURE OVER THE REGION. WE WILL BE IN
THE NEXT LOW/S WARM SECTOR WITH 850MB TEMPS AROUND 18C. THEREFORE
RAISED HIGH TEMPS INTO THE MID 80S AWAY FROM THE LAKE. THE WEAK
PRESSURE GRADIENT WILL ALLOW A LAKE BREEZE TO FORM AND KEEP THE IL
LAKEFRONT AROUND 80. GUIDANCE HAS SLOWED THE NEXT LOW SO PUSHED
BACK POPS SUNDAY NIGHT.
JEE
MONDAY...
UPPER WAVE DIGGING TOWARDS THE INTERMOUNTAIN WEST THIS AFTERNOON
WILL LIFT ACROSS THE PLAINS INTO THE UPPER MIDWEST ON MONDAY WITH
ATTENDANT SURFACE LOW DEEPENING AS IT LIFTS ACROSS ONTARIO TO NEAR
JAMES BAY BY LATE MONDAY. A SURFACE FRONT WILL SLOWLY PUSH ACROSS
THE REGION MONDAY AND GUIDANCE HAS TRENDED TOWARDS A SLOWER SOLUTION
OVER THE LAST 24 HOURS. MODERATE TO STRONG INSTABILITY IS PROGGED TO
DEVELOP ALONG AND AHEAD OF THE FRONT WHERE THE GFS ADVERTISES A
CORRIDOR OF JUST OVER 2000 J/KG MLCAPE JUST TO THE WEST OF THE CWA
MONDAY AFTERNOON. THE BETTER CONVERGENCE ASSOCIATED WITH THE COLD
FRONT MAY ARRIVE JUST PAST THE MOST FAVORABLE DIURNAL TIMING IF
TIMING TRENDS HOLD TRUE...BUT THE RIGHT ENTRANCE REGION TO THE UPPER
JET IS PROGGED TO MOVE OVER THE AREA BY MID TO LATE IN THE EVENING
WITH DEEP LAYER SHEAR VALUES INCREASING TO AROUND 40 KT OR SO WHICH
WOULD BE SUFFICIENT FOR AN ORGANIZED SEVERE WEATHER THREAT...THOUGH
THIS THREAT SHOULD DIMINISH WEST TO EAST AS WE GET LATER INTO THE
OVERNIGHT HOURS AND THE BOUNDARY LAYER STABILIZES.
TUESDAY THROUGH THURSDAY...
A SECONDARY SHORTWAVE TROUGH IS PROGGED TO PUSH ACROSS THE REGION ON
TUESDAY BRINGING ADDITIONAL CHANCES FOR SHOWER AND THUNDERSTORMS
MAINLY ACROSS SOUTH/SOUTHEASTERN PORTIONS OF THE CWA WHERE THE
FRONTAL BOUNDARY MAY STILL SLOWLY BE MAKING A PUSH. MODERATE TO
STRONG HEIGHTS RISES QUICKLY BUILD IN BEHIND THIS FEATURE THOUGH AND
SHOULD RESULT IN A DRY WEATHER FOR MOST OF THE FORECAST AREA
TUESDAY. THE GFS IS PARTICULAR IS HOLDING ONTO SOME POPS NORTH OF
THE BOUNDARY WEDNESDAY INTO THURSDAY WHERE PERSISTENT WARM ADVECTION
WILL RESULT IN MID LEVEL ASCENT...THOUGH THE ECMWF REMAINS DRY THIS
PERIOD. WILL MAINTAIN SLIGHT CHANCE POPS IN THE MEANTIME.
FRIDAY THROUGH SATURDAY...
THERMAL RIDGE IS EXPECTED TO MOVE BACK OVERHEAD LATE IN THE WEEK
WITH H85 TEMPS PUSHING INTO THE LOW 20C RANGE WHICH WILL LEAD TO
ANOTHER WARMUP WITH TEMPS INTO THE UPPER 80S. ANOTHER SLOW MOVING
COLD FRONT WILL THEN SAG SOUTH ACROSS THE REGION BRINGING RENEWED
CHANCES FOR SHOWERS AND THUNDERSTORMS.
DEUBELBEISS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* NORTHWEST EXTENT OF CONVECTION WORKING INTO MDW AREA...AND WITH
LESS LIKELIHOOD...POSSIBLY ORD AS WELL.
* GUSTY SOUTHWEST WINDS DIMINISHING THIS EVENING.
* MVFR CIGS/VSBYS AND STRONGER GUSTS NEAR STORMS.
* IFR CIGS AND VSBYS POSSIBLE OVERNIGHT INTO EARLY SUNDAY.
LENNING
//DISCUSSION...UPDATED 18Z...
MODEL FORECAST DATA...SATELLITE IMAGERY...ACARS AIRCRAFT
SOUNDINGS...AND RECENT RADAR TRENDS ALL SUPPORT THE IDEA OF
INCREASED CONVECTIVE DEVELOPMENT THIS AFTERNOON...PRIMARILY
FOCUSED SOUTHEAST OF THE ORD/MDW TERMINALS. SO FAR THIS MORNING
INTO EARLY AFTERNOON THERE HAS BEEN LITTLE LIGHTNING WITH THE FEW
CELLS THAT HAVE DEVELOPED...BUT WOULD NOT BE SURPRISED TO SEE MORE
ACTIVE CONVECTION AS WE APPROACH PEAK DIURNAL HEATING. LESS
PRONOUNCED MOISTURE TRANSPORT NORTHWEST OF THIS CORRIDOR ALONG
WITH RELATIVELY WARM AIR ALOFT ARE THE FACTORS CONTRIBUTING TO
LESS CONFIDENCE OF WIDESPREAD AFTERNOON CONVECTION ACROSS THE
NORTHWEST HALF OF THE AREA...INCLUDING ORD/MDW AS WELL AS DPA AND
RFD. THE GYY TERMINAL WOULD BE ALONG THE NORTHWEST EDGE OF THE
AREA EXPECTED TO HAVE THE MORE EXTENSIVE COVERAGE.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM TO LOW CONFIDENCE THAT ALL TSRA STAYS SOUTHEAST OF
ORD/MDW TERMINALS THIS AFTERNOON...BUT GREATER CONFIDENCE THAT
MORE WIDESPREAD ACTIVITY DOES STAY SOUTHEAST.
* MEDIUM CONFIDENCE OF IFR CIGS AND VSBYS OVERNIGHT.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...VFR.
MONDAY...PERIODS OF TSRA LIKELY.
TUESDAY...SLIGHT CHANCE TSRA EARLY.
WEDNESDAY...SLIGHT CHANCE TSRA OVERNIGHT.
THURSDAY AND FRIDAY...CHANCE TSRA.
KREIN
&&
.MARINE...
221 PM CDT
MODERATE SOUTHWEST FLOW IS CURRENTLY IN PLACE ACROSS LAKE MICHIGAN
WHERE SOUTHWEST WINDS ARE GUSTING 20 TO 25 KTS WITH OCCASIONAL 30 KT
WINDS. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE NEARSHORE
WATERS THROUGH LATE THIS EVENING. THIS IS AHEAD OF LOW PRESSURE
CURRENTLY CENTERED NEAR GREEN BAY. THE LOW WILL DRAG A COLD FRONT
SOUTH ACROSS LAKE MICHIGAN TONIGHT TURNING WINDS TO THE NORTHWEST.
WINDS WILL ABATE BRIEFLY AS TRANSIENT HIGH PRESSURE PUSHES ACROSS
THE NORTHERN LAKES REGION...BUT BY MIDDAY SUNDAY WINDS ARE EXPECTED
TO BEGIN TO TURN SOUTHEAST AND START TO RAMP UP AGAIN AHEAD OF
ANOTHER AREA OF LOW PRESSURE. THIS NEXT WILL LOW LIFT FROM THE
NORTHERN PLAINS...DEEPENING AS IT HEADS TO HUDSON BAY MONDAY NIGHT
INTO TUESDAY. SOUTH WINDS ARE EXPECTED TO PEAK MONDAY OVER THE LAKE
WITH GUSTS SOLIDLY INTO THE 20 KT RANGE...APPROACHING 30 KT OVER THE
NORTH END OF THE LAKE. ANOTHER COLD FRONT WILL SAG SOUTH ACROSS LAKE
MICHIGAN MONDAY NIGHT.
DEUBELBEISS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 11 PM SATURDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
223 PM CDT SAT AUG 30 2014
.DISCUSSION...
221 PM CDT
SYNOPSIS...SCATTERED THUNDERSTORMS ARE POSSIBLE NW OF I-55 WHILE A
LINE OF STORMS WILL IMPACT AREAS ALONG AND EAST OF I-55 THROUGH THIS
EVENING. TOMORROW WILL BE DRY BUT UNSETTLED WEATHER RETURNS MONDAY
WITH MULTIPLE CHANCES FOR THUNDERSTORMS. SEVERE STORMS ARE POSSIBLE
MONDAY. TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE PERIOD WITH A
COUPLE DAYS GETTING INTO THE MID 80S.
THROUGH TONIGHT...
AN UPPER LEVEL TROUGH IS OVER THE UPPER MISSISSIPPI RIVER VALLEY AND
IT WILL PASS OVER THE REGION THROUGH THIS EVENING. A SURFACE LOW IS
OVER THE NORTHERN END OF LAKE MI WITH ITS COLD FRONT EXTENDING
THROUGH WI AND EASTERN IA. THE LOW WILL CONTINUE NE THROUGH THE
NIGHT.
HAVE MUCH HIGHER CONFIDENCE IN THE CONVECTIVE FORECAST TODAY
COMPARED TO YESTERDAY DUE TO CLEAR FORCING MECHANISMS. EXPECTING TO
HAVE TWO AREAS TO MONITOR. THE FIRST IS NORTHWEST OF I-55 WHERE
ISOLATED TO SCATTERED STORMS WILL CONTINUE TO FESTER THROUGH THIS
AFTERNOON AHEAD OF UPPER LEVEL WAVE AND COLD FRONT.
THE BIGGER CONCERN WILL BE ALONG AND SE OF I-55 WHERE A LINE OF
SHOWERS AND STORMS HAS ALREADY DEVELOPED. THE LATEST RAP ANALYSIS
SHOWS A NICE CORRIDOR OF MOISTURE CONVERGENCE WHERE THE CONVECTION
HAS FIRED. THE LATEST AMDAR SOUNDINGS ARE CAPLESS WITH 1000-1500
J/KG OF CAPE. HOWEVER...LAPSE RATES ARE POOR AND WIND SHEAR IS
MINIMAL AT BEST. THE AMDAR SOUNDINGS DO HAVE LOW LEVEL INVERTED
V/S AND THE RAP ANALYSIS HAS AROUND 1000 J/KG OF DOWNDRAFT CAPE.
THEREFORE NOT EXPECTING WIDESPREAD SEVERE WEATHER...BUT A STORM OR
TWO MAY PULSE UP AND PRODUCE SEVERE WINDS.
HEAVY DOWNPOURS ARE ALSO EXPECTED WITH PWAT VALUES OF 1.6-1.8
INCHES. BASED ON SHORT TERM GUIDANCE...THE AREA MOST CONCERNING IS
SOUTH OF A VALPARAISO IN TO GIBSON CITY IL LINE. STORMS WILL
CONTINUE TO DEVELOP AND MOVE OVER THIS REGION WITH AMPLE FORCING.
THEREFORE IF STORMS TRAIN OVER THE SAME AREA FOR AN EXTENDED PERIOD
OF TIME...FLASH FLOODING MAY OCCUR.
STORMS DIMINISH AND PUSH EAST OVERNIGHT WHILE HIGH PRESSURE SPREADS
OVER THE REGION. WINDS WILL DIMINISH AND FOG IS POSSIBLE.
SUNDAY...
SUNDAY LOOKS DRY WITH HIGH PRESSURE OVER THE REGION. WE WILL BE IN
THE NEXT LOW/S WARM SECTOR WITH 850MB TEMPS AROUND 18C. THEREFORE
RAISED HIGH TEMPS INTO THE MID 80S AWAY FROM THE LAKE. THE WEAK
PRESSURE GRADIENT WILL ALLOW A LAKE BREEZE TO FORM AND KEEP THE IL
LAKEFRONT AROUND 80. GUIDANCE HAS SLOWED THE NEXT LOW SO PUSHED
BACK POPS SUNDAY NIGHT.
JEE
MONDAY...
UPPER WAVE DIGGING TOWARDS THE INTERMOUNTAIN WEST THIS AFTERNOON
WILL LIFT ACROSS THE PLAINS INTO THE UPPER MIDWEST ON MONDAY WITH
ATTENDANT SURFACE LOW DEEPENING AS IT LIFTS ACROSS ONTARIO TO NEAR
JAMES BAY BY LATE MONDAY. A SURFACE FRONT WILL SLOWLY PUSH ACROSS
THE REGION MONDAY AND GUIDANCE HAS TRENDED TOWARDS A SLOWER SOLUTION
OVER THE LAST 24 HOURS. MODERATE TO STRONG INSTABILITY IS PROGGED TO
DEVELOP ALONG AND AHEAD OF THE FRONT WHERE THE GFS ADVERTISES A
CORRIDOR OF JUST OVER 2000 J/KG MLCAPE JUST TO THE WEST OF THE CWA
MONDAY AFTERNOON. THE BETTER CONVERGENCE ASSOCIATED WITH THE COLD
FRONT MAY ARRIVE JUST PAST THE MOST FAVORABLE DIURNAL TIMING IF
TIMING TRENDS HOLD TRUE...BUT THE RIGHT ENTRANCE REGION TO THE UPPER
JET IS PROGGED TO MOVE OVER THE AREA BY MID TO LATE IN THE EVENING
WITH DEEP LAYER SHEAR VALUES INCREASING TO AROUND 40 KT OR SO WHICH
WOULD BE SUFFICIENT FOR AN ORGANIZED SEVERE WEATHER THREAT...THOUGH
THIS THREAT SHOULD DIMINISH WEST TO EAST AS WE GET LATER INTO THE
OVERNIGHT HOURS AND THE BOUNDARY LAYER STABILIZES.
TUESDAY THROUGH THURSDAY...
A SECONDARY SHORTWAVE TROUGH IS PROGGED TO PUSH ACROSS THE REGION ON
TUESDAY BRINGING ADDITIONAL CHANCES FOR SHOWER AND THUNDERSTORMS
MAINLY ACROSS SOUTH/SOUTHEASTERN PORTIONS OF THE CWA WHERE THE
FRONTAL BOUNDARY MAY STILL SLOWLY BE MAKING A PUSH. MODERATE TO
STRONG HEIGHTS RISES QUICKLY BUILD IN BEHIND THIS FEATURE THOUGH AND
SHOULD RESULT IN A DRY WEATHER FOR MOST OF THE FORECAST AREA
TUESDAY. THE GFS IS PARTICULAR IS HOLDING ONTO SOME POPS NORTH OF
THE BOUNDARY WEDNESDAY INTO THURSDAY WHERE PERSISTENT WARM ADVECTION
WILL RESULT IN MID LEVEL ASCENT...THOUGH THE ECMWF REMAINS DRY THIS
PERIOD. WILL MAINTAIN SLIGHT CHANCE POPS IN THE MEANTIME.
FRIDAY THROUGH SATURDAY...
THERMAL RIDGE IS EXPECTED TO MOVE BACK OVERHEAD LATE IN THE WEEK
WITH H85 TEMPS PUSHING INTO THE LOW 20C RANGE WHICH WILL LEAD TO
ANOTHER WARMUP WITH TEMPS INTO THE UPPER 80S. ANOTHER SLOW MOVING
COLD FRONT WILL THEN SAG SOUTH ACROSS THE REGION BRINGING RENEWED
CHANCES FOR SHOWERS AND THUNDERSTORMS.
DEUBELBEISS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* PRIMARY CONCERN IS TIMING...EXTENT...AND DURATION OF TSRA THIS
AFTERNOON.
LENNING
//DISCUSSION...UPDATED 18Z...
MODEL FORECAST DATA...SATELLITE IMAGERY...ACARS AIRCRAFT
SOUNDINGS...AND RECENT RADAR TRENDS ALL SUPPORT THE IDEA OF
INCREASED CONVECTIVE DEVELOPMENT THIS AFTERNOON...PRIMARILY
FOCUSED SOUTHEAST OF THE ORD/MDW TERMINALS. SO FAR THIS MORNING
INTO EARLY AFTERNOON THERE HAS BEEN LITTLE LIGHTNING WITH THE FEW
CELLS THAT HAVE DEVELOPED...BUT WOULD NOT BE SURPRISED TO SEE MORE
ACTIVE CONVECTION AS WE APPROACH PEAK DIURNAL HEATING. LESS
PRONOUNCED MOISTURE TRANSPORT NORTHWEST OF THIS CORRIDOR ALONG
WITH RELATIVELY WARM AIR ALOFT ARE THE FACTORS CONTRIBUTING TO
LESS CONFIDENCE OF WIDESPREAD AFTERNOON CONVECTION ACROSS THE
NORTHWEST HALF OF THE AREA...INCLUDING ORD/MDW AS WELL AS DPA AND
RFD. THE GYY TERMINAL WOULD BE ALONG THE NORTHWEST EDGE OF THE
AREA EXPECTED TO HAVE THE MORE EXTENSIVE COVERAGE.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE THAT WIDESPREAD TSRA REMAINS SOUTHEAST OF
TERMINALS...BUT LOW CONFIDENCE OF NO TSRA AT ALL.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS.
* MEDIUM CONFIDENCE ON CEILING TRENDS.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...VFR.
MONDAY...PERIODS OF TSRA LIKELY.
TUESDAY...SLIGHT CHANCE TSRA EARLY.
WEDNESDAY...SLIGHT CHANCE TSRA OVERNIGHT.
THURSDAY AND FRIDAY...CHANCE TSRA.
KREIN
&&
.MARINE...
221 PM CDT
MODERATE SOUTHWEST FLOW IS CURRENTLY IN PLACE ACROSS LAKE MICHIGAN
WHERE SOUTHWEST WINDS ARE GUSTING 20 TO 25 KTS WITH OCCASIONAL 30 KT
WINDS. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE NEARSHORE
WATERS THROUGH LATE THIS EVENING. THIS IS AHEAD OF LOW PRESSURE
CURRENTLY CENTERED NEAR GREEN BAY. THE LOW WILL DRAG A COLD FRONT
SOUTH ACROSS LAKE MICHIGAN TONIGHT TURNING WINDS TO THE NORTHWEST.
WINDS WILL ABATE BRIEFLY AS TRANSIENT HIGH PRESSURE PUSHES ACROSS
THE NORTHERN LAKES REGION...BUT BY MIDDAY SUNDAY WINDS ARE EXPECTED
TO BEGIN TO TURN SOUTHEAST AND START TO RAMP UP AGAIN AHEAD OF
ANOTHER AREA OF LOW PRESSURE. THIS NEXT WILL LOW LIFT FROM THE
NORTHERN PLAINS...DEEPENING AS IT HEADS TO HUDSON BAY MONDAY NIGHT
INTO TUESDAY. SOUTH WINDS ARE EXPECTED TO PEAK MONDAY OVER THE LAKE
WITH GUSTS SOLIDLY INTO THE 20 KT RANGE...APPROACHING 30 KT OVER THE
NORTH END OF THE LAKE. ANOTHER COLD FRONT WILL SAG SOUTH ACROSS LAKE
MICHIGAN MONDAY NIGHT.
DEUBELBEISS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 11 PM SATURDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1247 PM CDT SAT AUG 30 2014
.DISCUSSION...
1235 PM CDT
MODEL FORECAST DATA...SATELLITE IMAGERY...ACARS AIRCRAFT
SOUNDINGS...AND RECENT RADAR TRENDS ALL SUPPORT THE IDEA OF
INCREASED CONVECTIVE DEVELOPMENT THIS AFTERNOON...PRIMARILY
FOCUSED SOUTHEAST OF THE I-55 CORRIDOR. SO FAR THIS MORNING INTO
EARLY AFTERNOON THERE HAS BEEN LITTLE LIGHTNING WITH THE FEW CELLS
THAT HAVE DEVELOPED...BUT WOULD NOT BE SURPRISED TO SEE MORE
ACTIVE CONVECTION AS WE APPROACH PEAK DIURNAL HEATING. LESS
PRONOUNCED MOISTURE TRANSPORT NORTHWEST OF THIS CORRIDOR ALONG
WITH RELATIVELY WARM AIR ALOFT ARE THE FACTORS CONTRIBUTING TO
LESS CONFIDENCE OF WIDESPREAD AFTERNOON CONVECTION ACROSS THE
NORTHWEST HALF OF THE AREA.
LENNING
&&
.PREV DISCUSSION...
344 AM CDT
THE MAIN FORECAST CONCERNS WILL CENTER AROUND CONVECTIVE CHANCES AND
TIMING THROUGH THE PERIOD...ALONG WITH THE THREAT FOR STRONG TO
SEVERE CONVECTION...ESPECIALLY MONDAY.
WATER VAPOR IMAGERY EARLY THIS MORNING INDICATES TWO MID/UPPER LEVEL
DISTURBANCES OF INTEREST FOR TODAY AND TONIGHTS WEATHER. THE FIRST IS
LOCATED OVER IOWA AND INTO EXTREME NORTHERN MISSOURI...AND THIS IS
DRIVING AN AREA OF SHOWERS AND SOME EMBEDDED STORMS INTO WESTERN
ILLINOIS AT THIS HOUR. THIS WAVE IS EXPECTED TO LIFT NORTHEASTWARD
ACROSS WISCONSIN LATER THIS MORNING...AND AS IT DOES SO...A FEW
SCATTERED SHOWERS AND A THUNDERSTORM OR TWO CAN BE EXPECTED ACROSS
NORTHERN ILLINOIS. A SECOND DISTURBANCE IS CURRENTLY LOCATED ACROSS
THE EASTERN DAKOTAS SOUTHWARD INTO EASTERN NEBRASKA. THIS WAVE IS
EXPECTED TO SHIFT EASTWARD ACROSS WISCONSIN AND NORTHERN ILLINOIS
DURING THE AFTERNOON TODAY. THESE TWO DISTURBANCES WILL HELP INDUCE
A UPPER LEVEL 60+ KT SPEED MAX ACROSS THE LOWER GREAT LAKES
REGION...ESSENTIALLY SETTING UP PORTIONS OF MY AREA TO LINE UP WITHIN
THE FAVORABLE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET MAX THIS
AFTERNOON AND INTO TONIGHT. THIS SHOULD HELP TO DRIVE AN AREA OF
SHOWERS AND THUNDERSTORMS ACROSS PORTIONS OF THE AREA ALONG AND
AHEAD OF AN APPROACHING SURFACE COLD FRONT.
IT APPEARS THE BEST CHANCES FOR MORE ROBUST CONVECTIVE DEVELOPMENT
WILL BEGIN BY EARLY TO MID AFTERNOON OVER OR JUST TO THE SOUTH AND
EAST OF THE CHICAGO AREA. HIRES CONVECTIVE ALLOWING MODELS CONTINUE
TO INDICATE THE FAVORABLE LOCATIONS FOR AFTERNOON CONVECTIVE
ACTIVITY WILL PRIMARILY BE ALONG AND SOUTH OF A CHICAGO TO OTTAWA
LINE. ALTHOUGH MORNING SHOWERS AND CLOUD COVER COULD HAMPER
INSOLATION SOME ACROSS THE AREA...IT APPEARS THAT WITH DEW POINTS IN
THE LOWER 70S...MLCAPES SHOULD END UP AROUND 1500 J/KG...ESPECIALLY
ACROSS THE SOUTHEASTERN HALF OF MY AREA. THE INCREASING MID AND AN
UPPER LEVEL WIND FIELD ALSO LOOKS TO INCREASE THE DEEP LAYER SHEAR
UP TO 25 TO 30 KT...WHICH COULD SUPPORT A FEW STRONGER STORMS
CAPABLE OF STRONG WIND GUSTS. THESE STORMS WILL ALSO LIKELY PRODUCE
SOME TORRENTIAL DOWNPOURS GIVEN THE HIGH PWAT AIRMASS IN PLACE.
STORM MOTIONS OF 30 TO 40 KT SHOULD LIMIT THE RESIDENCE TIME OF
THESE STORMS OVER A GIVEN AREA...MAKING EXTREME RAINFALL AMOUNTS IN
A GIVEN AREA UNLIKELY. THESE STORMS LOOK TO LINGER INTO THE
EVENING HOURS TONIGHT...ESPECIALLY ACROSS MY FAR SOUTHEASTERN
COUNTIES IN NORTHWESTERN INDIANA AND EAST CENTRAL ILLINOIS.
SUNDAY STILL APPEARS TO BE THE PICK DAY OF THE WEEKEND...WITH A
TEMPORARY BREAK FROM THE SHOWER AND THUNDERSTORM ACTIVITY...WHICH
WILL RETURN BY LABOR DAY. THE WEATHER PATTERN WILL BECOME ACTIVE
AGAIN EARLY NEXT WEEK AS A SIGNIFICANT UPPER LEVEL DISTURBANCE AND
ASSOCIATED SPEED MAX...EMANATING FROM THE NORTHEASTERN
PACIFIC...DIGS ACROSS THE NORTHERN CONUS. THIS LOOKS TO SUPPORT A
SURFACE LOW...WHICH SHOULD SHIFT NORTHEASTWARD ACROSS THE UPPER
MIDWEST AND INTO ONTARIO BY MONDAY. CONVECTIVE ACTIVITY...POSSIBLY
STRONG TO SEVERE WILL BE FAVORED LATE SUNDAY FROM KANSAS
NORTHEASTWARD ACROSS ACROSS IOWA AND MINNESOTA AHEAD OF AN
APPROACHING COLD FRONT. THIS COLD FRONT IS EXPECTED TO MOVE INTO
NORTHERN ILLINOIS DURING THE DAY MONDAY...AND IT APPEARS THE DIURNAL
TIMING OF THIS FRONT...AND UPPER LEVEL SYSTEM...COULD BE FAVORABLE
FOR STRONG TO SEVERE CONVECTION ACROSS THE AREA MONDAY AFTERNOON AND
EVENING...ESPECIALLY CONSIDERING THE DEEP LAYER SHEAR IS EXPECTED TO
BE MORE THAN ADEQUATE FOR ORGANIZED STRONG CONVECTION.
UNCERTAINTY INCREASES A BIT LATER MONDAY NIGHT INTO TUESDAY...AS THE
VARIOUS MODEL GUIDANCE ARE IN DISAGREEMENT IN HOW FAST THE SURFACE
COLD FRONT WILL PUSH ACROSS MY ENTIRE AREA. THE ECMWF IS SUGGESTING
A SLOWER MOVEMENT OF THE FRONTAL BOUNDARY INTO TUESDAY AS IT
SUGGESTS THAT ANOTHER MID LEVEL IMPULSE WILL SHIFT OVER THE AREA
LEADING TO THE DEVELOPMENT OF A SECONDARY SURFACE LOW OVER THE AREA.
IF THIS SOLUTION WERE TO PAN OUT...IT COULD SET THE STAGE FOR SOME
VERY HEAVY RAINFALL AMOUNTS ACROSS PORTIONS OF THE AREA INTO TUESDAY
MORNING.
DURING THE MID TO LATER PORTION OF THE WEEK IT APPEARS THINGS WILL
BE ON A WARMING TREND...ESPECIALLY BY THURSDAY AS MID LEVEL HEIGHTS
BUILD SUBSTANTIALLY ACROSS THE AREA. THIS COULD LEAD TO A RUN AT
UPPER 80 TO LOWER 90 TEMPERATURES FOR THURSDAY. I CONTINUED WITH
SLIGHT CHANCE POPS DURING THE LATER PERIOD...MAINLY DUE TO
UNCERTAINTIES ON WHETHER OR NOT ANY SMALL SCALE DISTURBANCES WILL TRY
TO SPARK OFF CONVECTION OVER THE AREA. HOWEVER...WITH THE BUILDING
HEIGHTS AND WARMING TEMPERATURES ALOFT...THE AREA COULD END UP
CAPPED TO CONVECTIVE DEVELOPMENT ON WEDNESDAY AND THURSDAY.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* PRIMARY CONCERN IS TIMING...EXTENT...AND DURATION OF TSRA THIS
AFTERNOON.
LENNING
//DISCUSSION...UPDATED 18Z...
MODEL FORECAST DATA...SATELLITE IMAGERY...ACARS AIRCRAFT
SOUNDINGS...AND RECENT RADAR TRENDS ALL SUPPORT THE IDEA OF
INCREASED CONVECTIVE DEVELOPMENT THIS AFTERNOON...PRIMARILY
FOCUSED SOUTHEAST OF THE ORD/MDW TERMINALS. SO FAR THIS MORNING
INTO EARLY AFTERNOON THERE HAS BEEN LITTLE LIGHTNING WITH THE FEW
CELLS THAT HAVE DEVELOPED...BUT WOULD NOT BE SURPRISED TO SEE MORE
ACTIVE CONVECTION AS WE APPROACH PEAK DIURNAL HEATING. LESS
PRONOUNCED MOISTURE TRANSPORT NORTHWEST OF THIS CORRIDOR ALONG
WITH RELATIVELY WARM AIR ALOFT ARE THE FACTORS CONTRIBUTING TO
LESS CONFIDENCE OF WIDESPREAD AFTERNOON CONVECTION ACROSS THE
NORTHWEST HALF OF THE AREA...INCLUDING ORD/MDW AS WELL AS DPA AND
RFD. THE GYY TERMINAL WOULD BE ALONG THE NORTHWEST EDGE OF THE
AREA EXPECTED TO HAVE THE MORE EXTENSIVE COVERAGE.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE THAT WIDESPREAD TSRA REMAINS SOUTHEAST OF
TERMINALS...BUT LOW CONFIDENCE OF NO TSRA AT ALL.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS.
* MEDIUM CONFIDENCE ON CEILING TRENDS.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...VFR.
MONDAY...PERIODS OF TSRA LIKELY.
TUESDAY...SLIGHT CHANCE TSRA EARLY.
WEDNESDAY...SLIGHT CHANCE TSRA OVERNIGHT.
THURSDAY AND FRIDAY...CHANCE TSRA.
KREIN
&&
.MARINE...
300 AM CDT
A PERIOD OF ACTIVE WEATHER IS SETTING UP FOR LAKE MICHIGAN FOR
THE NEXT SEVERAL DAYS. A SERIES OF WEAK LOW PRESSURE SYSTEMS WILL
TRACK ACROSS THE UPPER GREAT LAKES REGION INTO CANADA DRAGGING
WEAK COLD FRONTS ACROSS THE LAKE. MODERATE SOUTH TO SOUTHWESTERLY
WINDS WILL PERSIST ACROSS THE LAKE THROUGH MUCH OF SATURDAY UNTIL
THE FIRST OF THE COLD FRONTS SWEEPS ACROSS THE LAKE LATE THIS
AFTERNOON AND THIS EVENING...TURNING WINDS TO NORTHWESTERLY
TONIGHT. A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD IN
BEHIND THE FRONT...ALLOWING WINDS TO DROP OFF AND BECOME MORE
VARIABLE IN DIRECTION EARLY SUNDAY. BY SUNDAY AFTERNOON...ANOTHER
DEVELOPING LOW OVER THE NORTHERN PLAINS WILL LEAD TO STRENGTHENING
SOUTHERLY WINDS FOR MONDAY AND MONDAY EVENING...UP TO 25 KT...BUT
THE NEXT FRONT WILL CROSS THE LAKE MONDAY NIGHT. THIS FRONTAL
PASSAGE WILL NOT BE AS ABRUPT AS THE FIRST WITH WINDS ONLY VEERING
SOUTHWESTERLY. WINDS SHOULD INCREASE AGAIN TO UP TO 25KT
IMMEDIATELY FOLLOWING THE FRONTAL PASSAGE MONDAY NIGHT...BUT SHOULD
THEN WEAKEN SLIGHTLY INTO MIDWEEK WHILE REMAINING GENERALLY
SOUTHWESTERLY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1236 PM CDT Sat Aug 30 2014
.UPDATE...
ISSUED AT 1052 AM CDT SAT AUG 30 2014
Much of central Illinois remains convection-free this morning,
except for the far SE KILX CWA south of I-70 where showers and
thunderstorms are ongoing. 15z/10am visible satellite imagery is
beginning to show an enhanced band of Cu along the Illinois River
that will eventually become a broken line of thunderstorms this
afternoon. HRRR shows storms developing along the I-55 corridor
after 20z, so have adjusted PoPs accordingly. Have focused likely
PoPs along/east of I-55 by mid-afternoon into the early evening
hours. Further west, will only carry low chances along/west of the
Illinois River this afternoon, then dry by evening.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 401 AM CDT SAT AUG 30 2014
Lift associated with an upper level shortwave trough over eastern
Iowa moving east-northeastward this morning is providing a focus for
a line of convection moving into western Illinois while a weaker
line of showers roughly along I-57 continues in eastern Illinois.
Cold front associated with the trough to our west is expected to
move to around to IA/IL border and stall out as the upper level
shortwave lifts northeastward bringing a continued focus for
precipitation for much of the next 24 hours. Rich moisture of close
to 2 inches will continue to stream into southeast Illinois to bring
the best chances for precipitation in that region. Tonight, as the
main trough shifts eastward, drier air continues to push eastward
allowing drier conditions to spread eastward into Illinois. As a
result, have pops trending downward overnight. Temperatures will be
down slightly today and tonight.
&&
.LONG TERM...(Sunday through Friday)
ISSUED AT 401 AM CDT SAT AUG 30 2014
Lingered a chance of showers and thunderstorms over southeast IL
Sunday where more clouds will be over eastern/se IL. Best chances of
convection will be southeast of Ohio river across KY where short
wave energy will be. Highs in the low to mid 80s Sunday (warmest
over western areas) and humid with dewpoints mostly in the lower
70s. Dry conditions across area Sunday evening then have chance of
showers and thunderstorms returning to areas nw of I-55 overnight
Sunday night. This due to approaching strong upper level trof over
Pacific Northwest that brings a cold front se through IL Monday
night. Quite warm and humid again on Monday with highs in the 80s
and dewpoints in the lower to middle 70s. Chances of showers and
thunderstorms increase from nw to se during the day Monday with
highest chances Monday afternoon/evening, gradually shifting chances
se overnight Monday night. SPC has much of central IL in a slight
chance of severe storms Monday afternoon/evening for damaging winds
and large hail. Surface to 6km bulk shear around 40 kts and CAPES
2-3K J/Kg supports this risk of severe storms from I-70 nw.
Upper level flow to become zonal by middle of next week and frontal
boundary likely not to get too far south of IL. Thus will continue
chances of showers and thunderstorms Tue with best chances (40-50%)
in southeast IL closer to frontal boundary while slight chances nw
of IL river. Just slight chances by Wed-Thu night and quite warm and
humid with highs in the mid to upper 80s and even approaching
lower 90s over southern areas Thu and Friday. This is due to
upper level ridge of 593 dm 500 mb high building over KY/TN. Next
frontal boundary to press se toward IL later Friday into Saturday
of next week increasing chances of showers and thunderstorms followed
by cooler weather next weekend.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1236 PM CDT SAT AUG 30 2014
Robust Cu-field continues to develop between the Illinois River
and I-55 early this afternoon: however, 1728z radar imagery
remains clear. As instability slowly increases, am expecting
scattered thunderstorms to develop along this corridor after
19/20z. Given timing and areal coverage uncertainties, have
included VCTS at all terminals beginning at 18z. As the afternoon
progresses, think main area of concern will shift east of the
Illinois River Valley, so have dropped VCTS at KPIA after 22z.
Further east, will maintain thunder mention through 05z, allowing
plenty of time for any diurnally driven storms to dissipate after
sunset. Once convection ends, skies will partially clear and winds
will become quite light overnight. Forecast soundings and numeric
guidance both suggest patchy fog, particularly across the western
KILX CWA where winds will be lightest. As a result, have included
reduced visbys down to 2-3sm between 09z and 13z.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BARNES
SHORT TERM...ONTON
LONG TERM...07
AVIATION...BARNES
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1118 AM CDT SAT AUG 30 2014
.DISCUSSION...
344 AM CDT
THE MAIN FORECAST CONCERNS WILL CENTER AROUND CONVECTIVE CHANCES AND
TIMING THROUGH THE PERIOD...ALONG WITH THE THREAT FOR STRONG TO
SEVERE CONVECTION...ESPECIALLY MONDAY.
WATER VAPOR IMAGERY EARLY THIS MORNING INDICATES TWO MID/UPPER LEVEL
DISTURBANCES OF INTEREST FOR TODAY AND TONIGHTS WEATHER. THE FIRST IS
LOCATED OVER IOWA AND INTO EXTREME NORTHERN MISSOURI...AND THIS IS
DRIVING AN AREA OF SHOWERS AND SOME EMBEDDED STORMS INTO WESTERN
ILLINOIS AT THIS HOUR. THIS WAVE IS EXPECTED TO LIFT NORTHEASTWARD
ACROSS WISCONSIN LATER THIS MORNING...AND AS IT DOES SO...A FEW
SCATTERED SHOWERS AND A THUNDERSTORM OR TWO CAN BE EXPECTED ACROSS
NORTHERN ILLINOIS. A SECOND DISTURBANCE IS CURRENTLY LOCATED ACROSS
THE EASTERN DAKOTAS SOUTHWARD INTO EASTERN NEBRASKA. THIS WAVE IS
EXPECTED TO SHIFT EASTWARD ACROSS WISCONSIN AND NORTHERN ILLINOIS
DURING THE AFTERNOON TODAY. THESE TWO DISTURBANCES WILL HELP INDUCE
A UPPER LEVEL 60+ KT SPEED MAX ACROSS THE LOWER GREAT LAKES
REGION...ESSENTIALLY SETTING UP PORTIONS OF MY AREA TO LINE UP WITHIN
THE FAVORABLE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET MAX THIS
AFTERNOON AND INTO TONIGHT. THIS SHOULD HELP TO DRIVE AN AREA OF
SHOWERS AND THUNDERSTORMS ACROSS PORTIONS OF THE AREA ALONG AND
AHEAD OF AN APPROACHING SURFACE COLD FRONT.
IT APPEARS THE BEST CHANCES FOR MORE ROBUST CONVECTIVE DEVELOPMENT
WILL BEGIN BY EARLY TO MID AFTERNOON OVER OR JUST TO THE SOUTH AND
EAST OF THE CHICAGO AREA. HIRES CONVECTIVE ALLOWING MODELS CONTINUE
TO INDICATE THE FAVORABLE LOCATIONS FOR AFTERNOON CONVECTIVE
ACTIVITY WILL PRIMARILY BE ALONG AND SOUTH OF A CHICAGO TO OTTAWA
LINE. ALTHOUGH MORNING SHOWERS AND CLOUD COVER COULD HAMPER
INSOLATION SOME ACROSS THE AREA...IT APPEARS THAT WITH DEW POINTS IN
THE LOWER 70S...MLCAPES SHOULD END UP AROUND 1500 J/KG...ESPECIALLY
ACROSS THE SOUTHEASTERN HALF OF MY AREA. THE INCREASING MID AND AN
UPPER LEVEL WIND FIELD ALSO LOOKS TO INCREASE THE DEEP LAYER SHEAR
UP TO 25 TO 30 KT...WHICH COULD SUPPORT A FEW STRONGER STORMS
CAPABLE OF STRONG WIND GUSTS. THESE STORMS WILL ALSO LIKELY PRODUCE
SOME TORRENTIAL DOWNPOURS GIVEN THE HIGH PWAT AIRMASS IN PLACE.
STORM MOTIONS OF 30 TO 40 KT SHOULD LIMIT THE RESIDENCE TIME OF
THESE STORMS OVER A GIVEN AREA...MAKING EXTREME RAINFALL AMOUNTS IN
A GIVEN AREA UNLIKELY. THESE STORMS LOOK TO LINGER INTO THE
EVENING HOURS TONIGHT...ESPECIALLY ACROSS MY FAR SOUTHEASTERN
COUNTIES IN NORTHWESTERN INDIANA AND EAST CENTRAL ILLINOIS.
SUNDAY STILL APPEARS TO BE THE PICK DAY OF THE WEEKEND...WITH A
TEMPORARY BREAK FROM THE SHOWER AND THUNDERSTORM ACTIVITY...WHICH
WILL RETURN BY LABOR DAY. THE WEATHER PATTERN WILL BECOME ACTIVE
AGAIN EARLY NEXT WEEK AS A SIGNIFICANT UPPER LEVEL DISTURBANCE AND
ASSOCIATED SPEED MAX...EMANATING FROM THE NORTHEASTERN
PACIFIC...DIGS ACROSS THE NORTHERN CONUS. THIS LOOKS TO SUPPORT A
SURFACE LOW...WHICH SHOULD SHIFT NORTHEASTWARD ACROSS THE UPPER
MIDWEST AND INTO ONTARIO BY MONDAY. CONVECTIVE ACTIVITY...POSSIBLY
STRONG TO SEVERE WILL BE FAVORED LATE SUNDAY FROM KANSAS
NORTHEASTWARD ACROSS ACROSS IOWA AND MINNESOTA AHEAD OF AN
APPROACHING COLD FRONT. THIS COLD FRONT IS EXPECTED TO MOVE INTO
NORTHERN ILLINOIS DURING THE DAY MONDAY...AND IT APPEARS THE DIURNAL
TIMING OF THIS FRONT...AND UPPER LEVEL SYSTEM...COULD BE FAVORABLE
FOR STRONG TO SEVERE CONVECTION ACROSS THE AREA MONDAY AFTERNOON AND
EVENING...ESPECIALLY CONSIDERING THE DEEP LAYER SHEAR IS EXPECTED TO
BE MORE THAN ADEQUATE FOR ORGANIZED STRONG CONVECTION.
UNCERTAINTY INCREASES A BIT LATER MONDAY NIGHT INTO TUESDAY...AS THE
VARIOUS MODEL GUIDANCE ARE IN DISAGREEMENT IN HOW FAST THE SURFACE
COLD FRONT WILL PUSH ACROSS MY ENTIRE AREA. THE ECMWF IS SUGGESTING
A SLOWER MOVEMENT OF THE FRONTAL BOUNDARY INTO TUESDAY AS IT
SUGGESTS THAT ANOTHER MID LEVEL IMPULSE WILL SHIFT OVER THE AREA
LEADING TO THE DEVELOPMENT OF A SECONDARY SURFACE LOW OVER THE AREA.
IF THIS SOLUTION WERE TO PAN OUT...IT COULD SET THE STAGE FOR SOME
VERY HEAVY RAINFALL AMOUNTS ACROSS PORTIONS OF THE AREA INTO TUESDAY
MORNING.
DURING THE MID TO LATER PORTION OF THE WEEK IT APPEARS THINGS WILL
BE ON A WARMING TREND...ESPECIALLY BY THURSDAY AS MID LEVEL HEIGHTS
BUILD SUBSTANTIALLY ACROSS THE AREA. THIS COULD LEAD TO A RUN AT
UPPER 80 TO LOWER 90 TEMPERATURES FOR THURSDAY. I CONTINUED WITH
SLIGHT CHANCE POPS DURING THE LATER PERIOD...MAINLY DUE TO
UNCERTAINTIES ON WHETHER OR NOT ANY SMALL SCALE DISTURBANCES WILL TRY
TO SPARK OFF CONVECTION OVER THE AREA. HOWEVER...WITH THE BUILDING
HEIGHTS AND WARMING TEMPERATURES ALOFT...THE AREA COULD END UP
CAPPED TO CONVECTIVE DEVELOPMENT ON WEDNESDAY AND THURSDAY.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* STILL CONCERNED ABOUT LOCAL TSRA TRENDS BUT ALSO NOT CONFIDENT
ENOUGH IN TIMING OR LOCATION OR DURATION TO INCLUDE IN TAF.
SHOWERS FORMING OVER WI ARE LIFTING NORTHEAST AND SO FAR ARE NOT
PRODUCING LIGHTNING.
LENNING
//DISCUSSION...UPDATED 12Z...
SCT SHRA AND ISOLD TSRA CONTINUE THROUGH THE DAY TODAY AS THE AREA
REMAINS ENTRENCHED IN A WARM/MOIST AIRMASS. A WEAK COLD FRONT IS
EXPECTED TO MOVE ACROSS THE AREA TODAY IN ASSOCIATION WITH A
STRONGER UPPER LEVEL TROUGH. THE UPPER TROUGH AND SFC FRONT SHOULD
PROVIDE SOME FOCUS FOR MORE THUNDERSTORM ACTIVITY. HOWEVER...THE
TIMING OF THE FRONT WILL PLAY A SIGNIFICANT ROLE IN THE TS
COVERAGE AS IT SHOULD MOVE NRN IL BY LATE MORNING...AT A TIME
BEFORE MAX DIURNAL WARMING. THE HIGH RESOLUTION MODEL GUIDANCE
SUGGESTS THAT TS COVERAGE SHOULD INCREASE AS THE FRONT MOVES
THROUGH ECNTRL IL AND NWRN IN DURG THE EARLY AFTERNOON HOURS.
HAVE OPTED TO GO WITH THE TEMPO GROUP FOR TS FOR THE MOST
FAVORABLE TIME FOR CONVECTIVE ACTIVITY OVER THE AREA...BUT THIS IS
STILL A LOW CONFIDENCE FORECAST.
WINDS SHOULD BECOME MORE SWLY WITH GUSTS TO 15-20KT FOR THE LATE
MORNING INTO EARLY EVENING AS SOME BREAKS IN THE OVERCAST ALLOWS
FOR SOME MIXING DOWN OF STRONGER WINDS ALOFT. WINDS SHOULD DROP
OFF AND BECOME LGT/VRBL OVERNIGHT AS HIGH PRESSURE SPREADS ACROSS
THE AREA. WITH CLEARING SKIES...LIGHT WINDS AND AMPLE RESIDUAL LOW
LEVEL MOISTURE IN PLACE...THERE IS AN INCREASING CHANCE FOR FOG
AND STATUS TO DEVELOP DURG THE LATE NIGHT HOURS TONIGHT.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* LOW TO MEDIUM CONFIDENCE OF TSRA STAYING OUT OF TERMINALS.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS EXCEPT NEAR STORMS.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...VFR.
MONDAY...PERIODS OF TSRA LIKELY.
TUESDAY...SLIGHT CHANCE TSRA EARLY.
WEDNESDAY...SLIGHT CHANCE TSRA OVERNIGHT.
THURSDAY AND FRIDAY...CHANCE TSRA.
KREIN
&&
.MARINE...
300 AM CDT
A PERIOD OF ACTIVE WEATHER IS SETTING UP FOR LAKE MICHIGAN FOR
THE NEXT SEVERAL DAYS. A SERIES OF WEAK LOW PRESSURE SYSTEMS WILL
TRACK ACROSS THE UPPER GREAT LAKES REGION INTO CANADA DRAGGING
WEAK COLD FRONTS ACROSS THE LAKE. MODERATE SOUTH TO SOUTHWESTERLY
WINDS WILL PERSIST ACROSS THE LAKE THROUGH MUCH OF SATURDAY UNTIL
THE FIRST OF THE COLD FRONTS SWEEPS ACROSS THE LAKE LATE THIS
AFTERNOON AND THIS EVENING...TURNING WINDS TO NORTHWESTERLY
TONIGHT. A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD IN
BEHIND THE FRONT...ALLOWING WINDS TO DROP OFF AND BECOME MORE
VARIABLE IN DIRECTION EARLY SUNDAY. BY SUNDAY AFTERNOON...ANOTHER
DEVELOPING LOW OVER THE NORTHERN PLAINS WILL LEAD TO STRENGTHENING
SOUTHERLY WINDS FOR MONDAY AND MONDAY EVENING...UP TO 25 KT...BUT
THE NEXT FRONT WILL CROSS THE LAKE MONDAY NIGHT. THIS FRONTAL
PASSAGE WILL NOT BE AS ABRUPT AS THE FIRST WITH WINDS ONLY VEERING
SOUTHWESTERLY. WINDS SHOULD INCREASE AGAIN TO UP TO 25KT
IMMEDIATELY FOLLOWING THE FRONTAL PASSAGE MONDAY NIGHT...BUT SHOULD
THEN WEAKEN SLIGHTLY INTO MIDWEEK WHILE REMAINING GENERALLY
SOUTHWESTERLY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1052 AM CDT Sat Aug 30 2014
.UPDATE...
ISSUED AT 1052 AM CDT SAT AUG 30 2014
Much of central Illinois remains convection-free this morning,
except for the far SE KILX CWA south of I-70 where showers and
thunderstorms are ongoing. 15z/10am visible satellite imagery is
beginning to show an enhanced band of Cu along the Illinois River
that will eventually become a broken line of thunderstorms this
afternoon. HRRR shows storms developing along the I-55 corridor
after 20z, so have adjusted PoPs accordingly. Have focused likely
PoPs along/east of I-55 by mid-afternoon into the early evening
hours. Further west, will only carry low chances along/west of the
Illinois River this afternoon, then dry by evening.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 401 AM CDT SAT AUG 30 2014
Lift associated with an upper level shortwave trough over eastern
Iowa moving east-northeastward this morning is providing a focus for
a line of convection moving into western Illinois while a weaker
line of showers roughly along I-57 continues in eastern Illinois.
Cold front associated with the trough to our west is expected to
move to around to IA/IL border and stall out as the upper level
shortwave lifts northeastward bringing a continued focus for
precipitation for much of the next 24 hours. Rich moisture of close
to 2 inches will continue to stream into southeast Illinois to bring
the best chances for precipitation in that region. Tonight, as the
main trough shifts eastward, drier air continues to push eastward
allowing drier conditions to spread eastward into Illinois. As a
result, have pops trending downward overnight. Temperatures will be
down slightly today and tonight.
&&
.LONG TERM...(Sunday through Friday)
ISSUED AT 401 AM CDT SAT AUG 30 2014
Lingered a chance of showers and thunderstorms over southeast IL
Sunday where more clouds will be over eastern/se IL. Best chances of
convection will be southeast of Ohio river across KY where short
wave energy will be. Highs in the low to mid 80s Sunday (warmest
over western areas) and humid with dewpoints mostly in the lower
70s. Dry conditions across area Sunday evening then have chance of
showers and thunderstorms returning to areas nw of I-55 overnight
Sunday night. This due to approaching strong upper level trof over
Pacific Northwest that brings a cold front se through IL Monday
night. Quite warm and humid again on Monday with highs in the 80s
and dewpoints in the lower to middle 70s. Chances of showers and
thunderstorms increase from nw to se during the day Monday with
highest chances Monday afternoon/evening, gradually shifting chances
se overnight Monday night. SPC has much of central IL in a slight
chance of severe storms Monday afternoon/evening for damaging winds
and large hail. Surface to 6km bulk shear around 40 kts and CAPES
2-3K J/Kg supports this risk of severe storms from I-70 nw.
Upper level flow to become zonal by middle of next week and frontal
boundary likely not to get too far south of IL. Thus will continue
chances of showers and thunderstorms Tue with best chances (40-50%)
in southeast IL closer to frontal boundary while slight chances nw
of IL river. Just slight chances by Wed-Thu night and quite warm and
humid with highs in the mid to upper 80s and even approaching
lower 90s over southern areas Thu and Friday. This is due to
upper level ridge of 593 dm 500 mb high building over KY/TN. Next
frontal boundary to press se toward IL later Friday into Saturday
of next week increasing chances of showers and thunderstorms followed
by cooler weather next weekend.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
ISSUED AT 658 AM CDT SAT AUG 30 2014
Scattered showers continue this morning mainly east of KDEC and
could produce isolated MVFR cig/vsby. As daytime heating
begins...expecting intensification of thunderstorm activity.
Location/timing of thunderstorms still uncertain at this time so
have limited mention to VCTS after 16Z-18Z. After 00Z...drying
conditions expected to begin spreading eastward across Illinois.
Western TAF sites KPIA-KSPI likely to see fog formation overnight
while eastern TAF sites KDEC-KCMI could see continued showers
overnight until around 12Z and have left VCSH in forecast.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BARNES
SHORT TERM...ONTON
LONG TERM...07
AVIATION...ONTON
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
340 PM EDT SAT AUG 30 2014
.SYNOPSIS...
ISSUED AT 335 PM EDT SAT AUG 30 2014
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO MOVE ACROSS
THE AREA THIS EVENING AS LOW PRESSURE TRACKS INTO THE NORTHERN GREAT
LAKES. SOME STORMS WILL PRODUCE BRIEF HEAVY RAIN AND STRONG GUSTY
WINDS. DRIER AIR WILL BRIEFLY WORK INTO THE AREA ON SUNDAY BEFORE
A COLD FRONT BRINGS RENEWED CHANCES FOR SHOWERS AND THUNDERSTORMS
ON MONDAY. LOWS WILL BE NEAR 70 WITH HIGHS ON SUNDAY AND MONDAY IN
THE LOW TO MID 80S.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 335 PM EDT SAT AUG 30 2014
CONVECTIVE DEVELOPMENT HAS TRIGGERED WHERE THE CLOUDS CLEARED
EARLIER TODAY...MAINLY OVER CENTRAL ILLINOIS TO LOWER LAKE
MICHIGAN AND INTO NORTHERN MICHIGAN. BEST SYNOPTIC SCALE FORCING
ASSOCIATED WITH THE LOW/TROF IN WISCONSIN. FLOW REGIME IS SUCH
THAT THE CONVECTION HAS DEVELOPED IN A STRETCHING DEFORMATION
AXIS. HRRR AND LOCAL WRF SHOW THE SFC BASED FRONTOGENESIS IN THIS
AXIS...
LAPSE RATES AND WIND PROFILES SUPPORT THE POTENTIAL FOR CONVECTIVE
LINES AND INDIVIDUAL LINE SEGMENTS. ISOLATED THREAT FOR SEVERE WIND
GUSTS. DO NOT EXPECT TO SEE SUSTAINED CONVECTIVE DEVELOPMENT AS THE
BOUNDARY LAYER FORCING DOES NOT PERSIST MUCH PAST 04Z.
LOW LEVEL JET KICKS IN OVERNIGHT AND THIS SHOULD BE ENOUGH TO
SUSTAIN MORE ORGANIZED SHRA/TSRA ACROSS THE SOUTHEASTERN HALF OF THE
FORECAST AREA. WHILE THERE IS DISCREPANCY IN TIMING AND INTENSITY
BETWEEN THE MODELS...THE BOUNDARY LAYER CAPE AND WIND PROFILES ARE
VERY SIMILAR AND DO SUPPORT PERSISTENT/LINGERING SHOWERS THROUGH
SUNDAY MORNING. WITH ABUNDANT MOISTURE TAP AND A LONG FETCH OF
ISENTROPIC ASSENT...SOME OF THE SHOWERS COULD PRODUCE MODERATE TO
LOCALLY HEAVY RAINFALL.
AS THE LOW LEVEL JET DECREASES AND THE TROF/DEFORMATION AXIS SHIFTS
EASTWARD...EXPECT IMPROVING CONDITIONS DURING THE DAY SUNDAY AHEAD
OF ANOTHER MORE ROBUST SYNOPTIC SYSTEM APPROACHING THE AREA FOR
MONDAY.
&&
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 335 PM EDT SAT AUG 30 2014
MAIN FOCUS OF LONG TERM IS ON PRECIP/SEVERE WEATHER CHANCES MONDAY
INTO MONDAY NIGHT. WELL DEFINED MID/UPPER LEVEL TROUGH CURRENTLY
DIGGING INTO THE PACIFIC NORTHWEST WILL SWING THROUGH THE GREAT
LAKES LATE MONDAY. TROUGH WILL BE LIFTING AS IT MOVES THROUGH THE
REGION BUT STRONG PUSH OF HEIGHT FALLS AND CVA WILL SUPPORT A DECENT
SURFACE CYCLONE AND ATTENDANT COLD FRONT. PRECIP CHANCES WILL BE
FURTHER AIDED BY GOOD RIGHT ENTRANCE JET DYNAMICS OVER THE SOUTHERN
GREAT LAKES. DEEP AND STRONG SOUTHWEST FLOW AHEAD OF THE TROUGH WILL
EASILY ADVECT HIGH THETA-E AIRMASS BACK INTO OUR AREA ON MONDAY.
AFTERNOON SBCAPE VALUES EXPECTED TO REACH THE 2-3 KJ/KG RANGE AS
HIGH TEMPS CLIMB INTO THE MID...OR PERHAPS UPPER...80S WITH SURFACE
DEWPOINTS IN THE LOW 70S. VERY DYNAMIC WAVE WILL LIKELY SUPPORT
NUMEROUS SHOWERS AND THUNDERSTORMS BUT TIMING WILL BE CRITICAL TO
SEVERE WEATHER CHANCES. LATEST 12Z NWP SUITE KEEPS SURFACE BOUNDARY
WEST OF OUR CWA UNTIL TUESDAY MORNING. ISO/SCT CONVECTION MAY
DEVELOP IN THE WARM SECTOR MONDAY AFTERNOON ALONG WEAK PREFRONTAL
TROUGH AS SUGGESTED BY THE LATEST NAM12 BUT EXPECT BULK OF THE
ACTIVITY WILL BE TIED TO THE ACTUAL COLD FRONT LATE MONDAY NIGHT.
BETTER WIND PROFILES...WITH 0-6KM SHEAR OF 30+ KNOTS...WILL ALSO BE
TIED CLOSER TO THE FRONT. DESPITE MORE THAN ADEQUATE
SHEAR...MIDLEVEL LAPSE RATES OF 6-7 C/KM ARE ONLY WEAKLY SUPPORTIVE
OF A NOCTURNAL SEVERE WEATHER THREAT. FORECAST SOUNDINGS INDICATE
ONLY AROUND 1000 J/KG OF ELEVATED INSTABILITY MONDAY NIGHT....PLENTY
FOR WIDESPREAD THUNDERSTORMS BUT SEVERE POTENTIAL IS LESS CLEAR.
THERE WILL BE A THREAT FOR SEVERE WINDS...AND POTENTIAL
ROTATION...WITH ANY SUBSTANTIVE UPDRAFTS THAT MANAGE TO DEVELOP BUT
LATE ARRIVAL OF FRONT MAY LIMIT CHANCES FOR A WIDESPREAD SEVERE
WEATHER EVENT. PUSHED BACK TIMING OF POPS BUT ALSO INCREASED THEM A
BIT BASED ON LATEST MODEL SOLUTIONS. COULD ALSO BE A THREAT FOR
STRONGER STORMS IN OUR FAR SOUTHEAST COUNTIES LATE TUESDAY MORNING
IF SURFACE BOUNDARY IS SLOW ENOUGH TO EXIT THE CWA.
QUIET WEATHER EXPECTED MIDWEEK BEFORE ANOTHER TROUGH APPROACHES NEXT
WEEKEND. SCT CONVECTION MAY BE POSSIBLE THURSDAY INTO FRIDAY AS WARM
FRONT LIFTS NORTH ONCE AGAIN BUT BEST CHANCES LOOK TO HOLD OFF UNTIL
THE WEEKEND. AFTER A BRIEF BREAK TUES AND WED...HEAT AND HUMIDITY
WILL RETURN FOR THE END OF THE WEEK AS ACTIVE WEATHER PATTERN
CONTINUES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 335 PM EDT SAT AUG 30 2014
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 142 PM EDT SAT AUG 30 2014
ABUMNDANT MOISTURE WILL CONTINUE TO SPREAD MVFR CONDITIONS
THROUGHOUT THE FORECAST PERIOD. WEAK COLD FRONT/SFC TROF HAS
CROSSED THE IL/IN BORDER AND CONVECTIVE DEVELOPMENT IS TRIGGERING
ALONG THE CLEARING / DIFFERENTIAL HEATING BOUNDARY IN ILLINOIS.
GIVEN SURFACE BASED CAPES AND CLEARING THIS WILL LIKELY BE THE
MOST FAVORED AREA FOR CONTINUED DEVELOPMENT LATE THIS AFTERNOON
THROUGH EARLY EVENING.
LAMINAR FLOW WILL KEEP CONVECTION MOVING QUICKLY NORTHEASTWARD
THROUGH THE LATE EVENING. LOW LEVEL JET KICKS UP AFTER SUNSET AND
COULD BE THE FOCUS FOR CONVECTIVE RE-DEVELOPMENT...ESPECIALLY KSBN
AND NORTH.
LATE TONIGHT/EARLY SUNDAY MORNING EXPECT TO SEE FOG FORM...
ESPECIALLY ACROSS THE WESTERN HALF OF THE FORECAST AREA.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR LMZ043-046.
&&
$$
SYNOPSIS...STEINWEDEL
SHORT TERM...LEWIS
LONG TERM...AGD
AVIATION...LEWIS
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AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
146 PM EDT SAT AUG 30 2014
LATEST UPDATE...
AVIATION
.SYNOPSIS...
ISSUED AT 327 AM EDT SAT AUG 30 2014
A LOW PRESSURE SYSTEM TRACKING THROUGH THE NORTHERN GREAT LAKES
WILL DRAG A COLD FRONT THROUGH THE SOUTHWEST LOWER MICHIGAN
TONIGHT. PERIODS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY
INTO THIS EVENING AHEAD OF THE COLD FRONT. IT WILL BE WARM AND
HUMID TODAY TOO. SUNDAY WILL FOR THE MOST PART BE PARTLY CLOUDY
WITH A SLIGHT CHANCE OF AN AFTERNOON THUNDERSTORM. IT WILL
CONTINUE TO BE WARM AND HUMID. A COLD FRONT PUSHING INTO THE AREA
ON LABOR DAY WILL BRING THE RISK FOR SEVERE STORMS IN THE
AFTERNOON. WARM AND HUMID CONDITIONS WILL CONTINUE.
&&
.UPDATE...
ISSUED AT 136 PM EDT SAT AUG 30 2014
INSTABILITY WAS BUILDING SLOWLY AS THE CLOUD COVER WAS ERODING
THIS AFTERNOON. MLCAPE VALUES NEAR 500 J/KG WITH MUCAPE VALUES UP
OVER 1500 J/KG AND EFFECTIVE SHEAR VALUES ARE AROUND 35 KNOTS.
STORMS BEGINNING TO DEVELOP AND A FEW COULD CONTAIN DAMAGING WIND
GUSTS AS INSTABILITY TRIES TO INCREASE. MID LEVEL WAVE MOVING IN
FROM WI WILL HELP TO TRIGGER ADDITIONAL STORMS. CONVECTION WILL
DECREASE THIS EVENING AS THE INSTABILITY WEAKENS.
UPDATE ISSUED AT 1032 AM EDT SAT AUG 30 2014
SATELLITE IMAGERY SHOWS DIMINISHING CLOUDS ACROSS LAKE MI. BASED
ON THE MOVEMENT...WE SHOULD SEE A PERIOD OF SUN THIS AFTERNOON.
AS A RESULT THE UPDATE FEATURES MORE SUNSHINE IN THE GRIDS. THIS
HEATING SUPPORTS THUNDERSTORMS DEVELOPING. WITH A LOW LEVEL JET
MOVING IN...THE STORMS COULD BECOME NUMEROUS. WILL KEEP THE HIGHER
POPS GOING FOR THE AFTERNOON. WILL NEED TO MONITOR THE SEVERE
POTENTIAL AS DEEP LAYER SHEAR CLIMBS ABOVE 30 KNOTS. HRRR RUC
SHOWS VERY LITTLE CONVECTION AFTER 19Z DESPITE THE ARRIVAL OF A
MID LEVEL WAVE.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 327 AM EDT SAT AUG 30 2014
WE HAVE TWO PERIODS OF CONVECTION TO WATCH IN THE SHORT TERM
FORECAST. THE THUNDERSTORMS AHEAD OF THE WEAK COLD FRONT THAT
COMES THROUGH THE AREA TONIGHT... THEN THE POSSIBLY SEVERE STORMS
ON LABOR DAY AS A STRONG JET STREAM INTERACTS WITH THE COLD FRONT
DURING MAX HEATING.
A QUICK OVERVIEW OF WHAT IS HAPPENING ON THE LARGER SCALE IS THE
SHEARING OUT SOUTHERN STREAM WAVE WE HAVE BEEN WATCHING FOR OVER
A WEEK NOW COMES THROUGH THE AREA TODAY. THE MODELS ALL SHOW THE
327 MB WAVE DEVELOPING A CLOSED UPPER LOW BY MID AFTERNOON. THE
ASSOCIATED DYNAMICS OF THE UPPER JET STREAM AND CORRESPONDING LOW
LEVEL JET WILL BRING THUNDERSTORMS TO THE AREA TODAY. THAT SYSTEM
MOVES OUT OF THE AREA LEAVING A SHORTWAVE RIDGE IN THE AREA
SUNDAY. THIS WILL RESULT IN QUIET WEATHER INTO SUNDAY NIGHT.
FINALLY A STRONG PACIFIC STORM BRINGS A NORTHERN STREAM WAVE INTO
THE AREA ON LABOR DAY. THIS WILL BRING STRONG JET DYNAMICS WITH IT
AND WILL RESULT IN A STRONG LOW LEVEL RESPONSE TO THE ASSOCIATED
COUPLED JET CORE MOVING THROUGH ON LABOR DAY.
AS FOR TODAY...THERE WILL BE TWO PERIODS OF CONVECTION. THE FIRST
WAVE IS ASSOCIATED WITH A INCREASE IN DEEP MOISTURE AND IS
LARGELY THE SYSTEM WARM FRONT COMING THROUGH. THIS HAS A LOW LEVEL
JET ASSOCIATED WITH IT AND THE AXIS OF THAT JET WILL BE FROM BTL
TO MBS BY MID MORNING. THIS WILL HELP DEVELOP STORMS OVER WESTERN
LOWER MICHIGAN THAT WILL MOVE EAST ACROSS THE STATE DURING THE
DAY. THEN THERE IS A SECOND LOW LEVEL JET ASSOCIATE WITH THE MAIN
UPPER WAVE. IT COMES ONTO SOUTHWEST MICHIGAN THIS AFTERNOON AND
INCREASE TO 35 TO 40 KNOTS NEAR LANSING BY 2 PM. THAT WILL DEVELOP
A SECOND AREA OF CONVECTION OVER WESTERN LOWER MICHIGAN THAT WILL
ALSO MOVE EAST BY LATE AFTERNOON. BY THEN MIX LAYER CAPES COULD BE
1500 J/KG SO AND THERE COULD BE AS MUCH AS 30 KNOTS OF EFFECT DEEP
LAYER SHEAR SO SOME STORMS MAY BE STRONG.
ALL OF THAT MOVES OUT LATE THIS EVENING AND SHORTWAVE RIDING
FOLLOWS SUNDAY. HOWEVER THERE IS STILL SOME INSTABILITY EVEN THOUGH
THE MID LEVELS (ABOVE 850 MB) IS RATHER DRY. I ADDED A SMALL
CHANCE OF AFTERNOON THUNDERSTORMS MOSTLY SOUTH OF I-96 IN THE
AFTERNOON FOR THAT.
THE MAIN STORY IS MONDAY WHEN THE UPPER LEVEL WAVE MOVES INTO VERY
UNSTABLE AIR. THE LOW LEVEL JET ON THE GFS IS FOCUSED ON SOUTHWEST
LOWER MICHIGAN IN THE AFTERNOON AND SHOWS OVER 3270 J/KG OF CAPE.
SO THERE IS REAL POTENTIAL FOR SEVERE STORMS.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 327 AM EDT SAT AUG 30 2014
THE MAIN FOCUS OF THE LONG TERM REMAINS ON THE SYSTEM THAT WILL BE
AFFECTING THE AREA DURING THE FIRST PART OF NEXT WEEK. THE FRONT
LOOKS TO START OUT MON EVENING TO OUR WEST YET. THIS WILL KEEP THE
THREAT OF STORMS IN THE FCST...ALTHOUGH THE THREAT OF SEVERE WEATHER
WILL BE DIMINISHING AS DIURNAL INSTABILITY WILL BE ON THE WANE A
BIT.
A RESIDUAL CHC OF SHOWERS AND STORMS WILL BE LEFT IN FOR THE DAY ON
TUE. THE FRONT LOOKS TO SINK JUST SOUTH OF THE AREA AND STALL OUT.
HOW FAR SOUTH IT STALLS IS UNCERTAIN WITH THE GFS A BIT FURTHER
SOUTH...AND THE EURO KEEPING IT CLOSER TO THE AREA. THIS FRONTAL
POSITION WILL BE IMPORTANT AS ANOTHER WAVE LOOKS TO MOVE THROUGH THE
REGION AND COULD BRING ANOTHER ROUND OF RAIN TO THE AREA ON TUE.
THE AREA SHOULD DRY OUT FOR WED WITH A RIDGE OF HIGH PRESSURE
BUILDING INTO THE AREA. THIS RIDGE WILL BE FAIRLY FLAT IN NATURE AND
WILL BE SHORT LIVED. A TROUGH EXPECTED TO COME ONSHORE OVER THE
PACIFIC NW DURING THE TUE TIME FRAME WILL PUSH A FRONTAL SYSTEM SE
INTO THE AREA LATE IN THE WEEK. PCPN CHCS WILL START ON THU AS A
WARM FRONT MOVES THROUGH THE AREA. THE COLD FRONT THEN FOLLOWS FOR
THE DAY ON FRI.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 145 PM EDT SAT AUG 30 2014
SCATTERED THUNDERSTORMS ARE EXPECTED...ESPECIALLY LATE THIS
AFTERNOON AND EARLY EVENING. THEN THE THREAT OF STORMS WILL BE
EXITING AROUND MIDNIGHT LOCAL TIME.
CONFIDENCE IN WIDESPREAD IFR LATE TONIGHT IN FOG WAS DIMINISHING
DUE TO THE ABUNDANT LOW CLOUDS THAT ARE EXPECTED TO REMAIN OVER
THE AREA. KEPT SOME IFR AROUND...BUT DID NOT HIT IT AS HARD. ANY
IFR SHOULD BE LIFTING OUT OF THE AREA BY LATE SUNDAY MORNING.
&&
.MARINE...
ISSUED AT 1032 AM EDT SAT AUG 30 2014
WAVES RUNNING 3 TO 5 FEET ALONG THE LAKESHORE. GIVEN THE VEERING
FLOW WITH GUSTS UP AROUND 25 KNOTS...HAZARDOUS CONDITIONS WILL
PERSIST INTO THE AFTERNOON. WINDS AND WAVES WILL GRADUALLY
DIMINISH LATER THIS AFTERNOON AND INTO THE EVENING.
&&
.HYDROLOGY...
ISSUED AT 307 PM EDT FRI AUG 29 2014
HEAVY RAIN IS A RISK THROUGH SATURDAY. VERY MOIST AIRMASS WILL ADVECT
INTO MI AS PWAT VALUES GENERALLY CLIMB ABOVE 1.5 INCHES. GIVEN THE
LACK OF DIRECTIONAL SHEAR...WE COULD SEE SOME TRAINING WHICH MAY
LEAD TO THE STORMS PERSISTING. IF THIS ENDS UP OCCURRING...SOME
LOCATIONS COULD EASILY SEE OVER 2 INCHES OF RAIN.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 11 PM EDT THIS EVENING FOR MIZ037-
043-050-056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...MJS
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...NJJ
AVIATION...JK
HYDROLOGY...MJS
MARINE...MJS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
136 PM EDT SAT AUG 30 2014
LATEST UPDATE...
UPDATE
.SYNOPSIS...
ISSUED AT 327 AM EDT SAT AUG 30 2014
A LOW PRESSURE SYSTEM TRACKING THROUGH THE NORTHERN GREAT LAKES
WILL DRAG A COLD FRONT THROUGH THE SOUTHWEST LOWER MICHIGAN
TONIGHT. PERIODS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY
INTO THIS EVENING AHEAD OF THE COLD FRONT. IT WILL BE WARM AND
HUMID TODAY TOO. SUNDAY WILL FOR THE MOST PART BE PARTLY CLOUDY
WITH A SLIGHT CHANCE OF AN AFTERNOON THUNDERSTORM. IT WILL
CONTINUE TO BE WARM AND HUMID. A COLD FRONT PUSHING INTO THE AREA
ON LABOR DAY WILL BRING THE RISK FOR SEVERE STORMS IN THE
AFTERNOON. WARM AND HUMID CONDITIONS WILL CONTINUE.
&&
.UPDATE...
ISSUED AT 136 PM EDT SAT AUG 30 2014
INSTABILITY WAS BUILDING SLOWLY AS THE CLOUD COVER WAS ERODING
THIS AFTERNOON. MLCAPE VALUES NEAR 500 JKG WITH MUCAPE VALUES UP
OVER 1500 J/KG AND EFFECTIVE SHEAR VALUES ARE AROUND 35 KNOTS.
STORMS BEGINNING TO DEVELOP AND A FEW COULD CONTAIN DAMAGING WIND
GUSTS AS INSTABILITY TRIES TO INCREASE. MID LEVEL WAVE MOVING IN
FROM WI WILL HELP TO TRIGGER ADDITIONAL STORMS. CONVECTION WILL
DECREASE THIS EVENING AS THE INSTABILITY WEAKENS.
UPDATE ISSUED AT 1032 AM EDT SAT AUG 30 2014
SATELLITE IMAGERY SHOWS DIMINISHING CLOUDS ACROSS LAKE MI. BASED
ON THE MOVEMENT...WE SHOULD SEE A PERIOD OF SUN THIS AFTERNOON.
AS A RESULT THE UPDATE FEATURES MORE SUNSHINE IN THE GRIDS. THIS
HEATING SUPPORTS THUNDERSTORMS DEVELOPING. WITH A LOW LEVEL JET
MOVING IN...THE STORMS COULD BECOME NUMEROUS. WILL KEEP THE HIGHER
POPS GOING FOR THE AFTERNOON. WILL NEED TO MONITOR THE SEVERE
POTENTIAL AS DEEP LAYER SHEAR CLIMBS ABOVE 30 KNOTS. HRRR RUC
SHOWS VERY LITTLE CONVECTION AFTER 19Z DESPITE THE ARRIVAL OF A
MID LEVEL WAVE.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 327 AM EDT SAT AUG 30 2014
WE HAVE TWO PERIODS OF CONVECTION TO WATCH IN THE SHORT TERM
FORECAST. THE THUNDERSTORMS AHEAD OF THE WEAK COLD FRONT THAT
COMES THROUGH THE AREA TONIGHT... THEN THE POSSIBLY SEVERE STORMS
ON LABOR DAY AS A STRONG JET STREAM INTERACTS WITH THE COLD FRONT
DURING MAX HEATING.
A QUICK OVERVIEW OF WHAT IS HAPPENING ON THE LARGER SCALE IS THE
SHEARING OUT SOUTHERN STREAM WAVE WE HAVE BEEN WATCHING FOR OVER
A WEEK NOW COMES THROUGH THE AREA TODAY. THE MODELS ALL SHOW THE
327 MB WAVE DEVELOPING A CLOSED UPPER LOW BY MID AFTERNOON. THE
ASSOCIATED DYNAMICS OF THE UPPER JET STREAM AND CORRESPONDING LOW
LEVEL JET WILL BRING THUNDERSTORMS TO THE AREA TODAY. THAT SYSTEM
MOVES OUT OF THE AREA LEAVING A SHORTWAVE RIDGE IN THE AREA
SUNDAY. THIS WILL RESULT IN QUIET WEATHER INTO SUNDAY NIGHT.
FINALLY A STRONG PACIFIC STORM BRINGS A NORTHERN STREAM WAVE INTO
THE AREA ON LABOR DAY. THIS WILL BRING STRONG JET DYNAMICS WITH IT
AND WILL RESULT IN A STRONG LOW LEVEL RESPONSE TO THE ASSOCIATED
COUPLED JET CORE MOVING THROUGH ON LABOR DAY.
AS FOR TODAY...THERE WILL BE TWO PERIODS OF CONVECTION. THE FIRST
WAVE IS ASSOCIATED WITH A INCREASE IN DEEP MOISTURE AND IS
LARGELY THE SYSTEM WARM FRONT COMING THROUGH. THIS HAS A LOW LEVEL
JET ASSOCIATED WITH IT AND THE AXIS OF THAT JET WILL BE FROM BTL
TO MBS BY MID MORNING. THIS WILL HELP DEVELOP STORMS OVER WESTERN
LOWER MICHIGAN THAT WILL MOVE EAST ACROSS THE STATE DURING THE
DAY. THEN THERE IS A SECOND LOW LEVEL JET ASSOCIATE WITH THE MAIN
UPPER WAVE. IT COMES ONTO SOUTHWEST MICHIGAN THIS AFTERNOON AND
INCREASE TO 35 TO 40 KNOTS NEAR LANSING BY 2 PM. THAT WILL DEVELOP
A SECOND AREA OF CONVECTION OVER WESTERN LOWER MICHIGAN THAT WILL
ALSO MOVE EAST BY LATE AFTERNOON. BY THEN MIX LAYER CAPES COULD BE
1500 J/KG SO AND THERE COULD BE AS MUCH AS 30 KNOTS OF EFFECT DEEP
LAYER SHEAR SO SOME STORMS MAY BE STRONG.
ALL OF THAT MOVES OUT LATE THIS EVENING AND SHORTWAVE RIDING
FOLLOWS SUNDAY. HOWEVER THERE IS STILL SOME INSTABILITY EVEN THOUGH
THE MID LEVELS (ABOVE 850 MB) IS RATHER DRY. I ADDED A SMALL
CHANCE OF AFTERNOON THUNDERSTORMS MOSTLY SOUTH OF I-96 IN THE
AFTERNOON FOR THAT.
THE MAIN STORY IS MONDAY WHEN THE UPPER LEVEL WAVE MOVES INTO VERY
UNSTABLE AIR. THE LOW LEVEL JET ON THE GFS IS FOCUSED ON SOUTHWEST
LOWER MICHIGAN IN THE AFTERNOON AND SHOWS OVER 3270 J/KG OF CAPE.
SO THERE IS REAL POTENTIAL FOR SEVERE STORMS.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 327 AM EDT SAT AUG 30 2014
THE MAIN FOCUS OF THE LONG TERM REMAINS ON THE SYSTEM THAT WILL BE
AFFECTING THE AREA DURING THE FIRST PART OF NEXT WEEK. THE FRONT
LOOKS TO START OUT MON EVENING TO OUR WEST YET. THIS WILL KEEP THE
THREAT OF STORMS IN THE FCST...ALTHOUGH THE THREAT OF SEVERE WEATHER
WILL BE DIMINISHING AS DIURNAL INSTABILITY WILL BE ON THE WANE A
BIT.
A RESIDUAL CHC OF SHOWERS AND STORMS WILL BE LEFT IN FOR THE DAY ON
TUE. THE FRONT LOOKS TO SINK JUST SOUTH OF THE AREA AND STALL OUT.
HOW FAR SOUTH IT STALLS IS UNCERTAIN WITH THE GFS A BIT FURTHER
SOUTH...AND THE EURO KEEPING IT CLOSER TO THE AREA. THIS FRONTAL
POSITION WILL BE IMPORTANT AS ANOTHER WAVE LOOKS TO MOVE THROUGH THE
REGION AND COULD BRING ANOTHER ROUND OF RAIN TO THE AREA ON TUE.
THE AREA SHOULD DRY OUT FOR WED WITH A RIDGE OF HIGH PRESSURE
BUILDING INTO THE AREA. THIS RIDGE WILL BE FAIRLY FLAT IN NATURE AND
WILL BE SHORT LIVED. A TROUGH EXPECTED TO COME ONSHORE OVER THE
PACIFIC NW DURING THE TUE TIME FRAME WILL PUSH A FRONTAL SYSTEM SE
INTO THE AREA LATE IN THE WEEK. PCPN CHCS WILL START ON THU AS A
WARM FRONT MOVES THROUGH THE AREA. THE COLD FRONT THEN FOLLOWS FOR
THE DAY ON FRI.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 732 AM EDT SAT AUG 30 2014
WHILE IT SHOWERS AND ISOLATED THUNDERSTORMS WILL BE AROUND TODAY
IT WOULD SEEM THE LOW LEVELS ARE DRY ENOUGH THAT CIGS/VSBY WILL
LARGELY BE VFR. I PUT VCTS THIS AFTERNOON AS IT IS EXPECTED SOME
CONVECTION WILL BE AROUND AHEAD OF THE WEAK COLD FRONT BUT THE
ACTIVITY WILL NOT BE CONCENTRATED ENOUGH TO NAIL DOWN THE TIMING
AT THIS POINT. TONIGHT ONCE THE FRONT COMES THROUGH IT WILL STALL
AND WINDS WILL BECOME LIGHT. I WOULD EXPECT LOW CIGS AND SOME IFR
FOG TO DEVELOP TOWARD SUNRISE SUNDAY.
&&
.MARINE...
ISSUED AT 1032 AM EDT SAT AUG 30 2014
WAVES RUNNING 3 TO 5 FEET ALONG THE LAKESHORE. GIVEN THE VEERING
FLOW WITH GUSTS UP AROUND 25 KNOTS...HAZARDOUS CONDITIONS WILL
PERSIST INTO THE AFTERNOON. WINDS AND WAVES WILL GRADUALLY
DIMINISH LATER THIS AFTERNOON AND INTO THE EVENING.
&&
.HYDROLOGY...
ISSUED AT 307 PM EDT FRI AUG 29 2014
HEAVY RAIN IS A RISK THROUGH SATURDAY. VERY MOIST AIRMASS WILL ADVECT
INTO MI AS PWAT VALUES GENERALLY CLIMB ABOVE 1.5 INCHES. GIVEN THE
LACK OF DIRECTIONAL SHEAR...WE COULD SEE SOME TRAINING WHICH MAY
LEAD TO THE STORMS PERSISTING. IF THIS ENDS UP OCCURRING...SOME
LOCATIONS COULD EASILY SEE OVER 2 INCHES OF RAIN.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 11 PM EDT THIS EVENING FOR MIZ037-
043-050-056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...MJS
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...NJJ
AVIATION...WDM
HYDROLOGY...MJS
MARINE...MJS
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON MS
559 PM CDT SAT AUG 30 2014
.UPDATE...SENDING OUT A QUICK UPDATE TO CLEAN UP ZFP WORDING AND TO
ACCOUNT FOR CURRENT PRECIP TRENDS. WITH MUCH OF THE AREA CURRENTLY
IN A BREAK...INDICATIONS ARE THERE WILL BE NEW DEVELOPMENT LATER IN
THE EVENING. MOST RECENT HRRR RUNS HAVE SUGGESTED ACTIVITY WILL BE
FARTHER EAST THAN EARLIER ANTICIPATED...CLOSER TO THE I-55 CORRIDOR.
POPS WERE ADJUSTED ACCORDINGLY. UPDATES ARE BEING SENT AT THIS TIME.
/DL/
&&
.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT...LARGE CONVECTIVE BLOB
MOVING ACROSS THE CWA AT THE MOMENT LOOKS TO RAPIDLY PULL AWAY TO
THE NE DURING THE EVENING. AT PRESENT...THIS SYSTEM HAS A FEW
TROPICAL CHARACTERISTICS THAT HAVE PROVIDED SOME INTERESTING WEATHER
ACROSS THE AREA TODAY. WET BULB ZERO HEIGHTS AROUND 15KFT ALONG WITH
PW/S NEAR 2.5 INCHES SUGGESTS THAT WARM RAIN PROCESSES HAVE BEEN
DOMINANT FOR MUCH OF LA/W MS THROUGH MOST OF THE DAY. THIS STRONG
RELEASE IN LATENT HEATING HAS RESULTED IN TROFFINESS AT THE SURFACE
AND 35-45 KNOTS OF H7 FLOW TO DEVELOP WITH SOME OF THESE WIND SPEEDS
TRANSLATING TO THE GROUND IN SOME OF THE HEAVIER CONVECTION. WHERE
THE SUN WAS ABLE TO GET ON THE GROUND...IN THE EAST...BETTER
INSTABILITY AND DEEPER CONVECTION HAS DEVELOPED WITH MORE ROBUST
UPDRAFTS AND LIGHTNING.
ALTHOUGH CONVECTION LOOKS TO REMAIN OVER THE AREA FOR A PORTION OF
TONIGHT...DECIDED NOT TO INCLUDE A LIMITED THREAT OF FLOODING OR
SEVERE AS THAT THREAT WILL QUICKLY WANE AS THE SYSTEM PULLS AWAY.
WHILE MID LEVEL RIDGING WILL TAKE HOLD ACROSS THE LOWER CONUS
THROUGH THE FIRST PART OF THE WEEK...WEAK CYCLONIC SHEAR AXIS LOOKS
TO REMAIN OVER THE ARKLAMISS AT LEAST THROUGH MONDAY. THIS COMBINED
WITH PW/S NEAR 2 INCHES WILL CONTINUE TO ALLOW ISOLATED SHOWERS AND
THUNDERSTORMS TO DEVELOP ALONG WITH THE BUILDING HEAT. LOWER 90S
PREVALENT SUNDAY WILL BE REPLACED BY MID 90S MONDAY./26/
.LONG TERM...TUESDAY THROUGH NEXT SATURDAY...NEAR TO SLIGHTLY ABOVE
NORMAL TEMPERATURES IN THE LOW TO MID 90S AND TYPICAL 20-30%
AFTERNOON CHANCES OF SHOWERS/STORMS THROUGH MOST OF THE WEEK AS A
HIGH PRESSURE RIDGE BUILDS OVER THE SE/CENTRAL CONUS.
DESPITE LOW-LVL HIGH PRESSURE AXIS AND SLOWLY BUILDING HEIGHT
INFLUENCE OVER REGION MOST OF THE WEEK, PWATS WILL REMAIN ELEVATED
/NEAR 2"/ AND COMBINED WITH DAILY AFTERNOON INSTABILITY /2000 J/KG+/,
ISOLATED/SCATTERED SHOWERS/STORMS WILL BE LIKELY. OVERALL COVERAGE
WONT BE GREAT BUT FEEL BEST COVERAGE WILL BE IN S/SE/E WHERE SEA-
BREEZE CONVERGENCE AND HIGHEST PWATS WILL EXIST. HEAT INDICES MONDAY
AND TUESDAY SHOULD REACH INTO THE LOW 100S FOR A FEW HOURS WITH LOWS
ONLY FALLING INTO THE LOW TO MID 70S THROUGH MUCH OF THE WEEK.
ON TUESDAY...A SLIGHTLY STRONGER S/WV TROUGH ACROSS THE CORN BELT
WILL ATTEMPT TO BRING A BOUNDARY SOUTH TOWARDS THE REGION BUT FEEL
IT STAY NORTH AND THUS KEPT POPS/SHOWERS OUT OF FORECAST FOR
NORTHERN AREAS. FOR WEDNESDAY THROUGH FRIDAY...RIDGING WILL REMAIN
OVER AREA AND STRENGTHEN SLIGHTLY BUT SEA-BREEZE INITIATED AND
DIURNAL ACTIVITY SHOULD CONTINUE TO BE A GOOD POSSIBILITY EACH DAY.
BY SATURDAY, THE RIDGING SLIPS FARTHER WEST AND PLACES REGION IN
SLIGHTLY GREATER N/NE FLOW THAT COULD ENHANCE SHOWER COVERAGE
POSSIBILITIES. /ALLEN/
&&
.AVIATION...RAIN COVERS MOST OF THE AREA WITH SOME EMBEDDED
THUNDERSTORMS. RAIN WAS TAPERING OFF FROM THE SOUTHWEST AND SHOULD
BE ENDING FOR GLH SHORTLY. WILL HAVE TO ADJUST THE OTHER SITES TO
END RAIN A LITTLE SOONER. WILL ALSO KEEP FOG BEFORE MIDNIGHT
EVERYWHERE. GUIDANCE SHOWS WINDS CONTINUING AROUND 10 KTS...BUT MUCH
OF THE AREA WAS LIGHT AND VARIABLE. WILL GO WITH THE LIGHTER WINDS
FOR THE EVENING./7/
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
DL/26/7/ALLEN
AREA FORECAST DISCUSSION
NWS BILLINGS MT
234 PM MDT SAT AUG 30 2014
.SHORT TERM...VALID FOR SUN AND MON...
SERIES OF SHORTWAVES IN THE CYCLONIC FLOW ALOFT ARE PROGRESSING
ACROSS THE FORECAST AREA THIS AFTERNOON. INITIAL SHORTWAVE IS
PUSHING ACROSS FAR EASTERN MONTANA AND WILL EXIT INTO THE DAKOTAS
LATER THIS AFTERNOON. A SECONDARY WAVE IS PUSHING INTO SOUTH
CENTRAL MONTANA OUT OF YELLOWSTONE PARK. LIGHTNING ACTIVITY HAS
BEEN MORE VIGOROUS WITH THIS WAVE ALL MORNING...EVEN BACK OVER
IDAHO EARLIER...INDICATING ENHANCED MID-LEVEL INSTABILITY. WOULD
STILL NOT RULE OUT A LINE OF THUNDERSTORMS DEVELOPING ACROSS
FALLON AND CARTER COUNTIES WITH THE INITIAL WAVE. IN
FACT...A THUNDERSTORM HAS STARTED TO DEVELOP NORTHEAST OF
GILLETTE WITH THIS LINE...AND IT REMAINS TO BE SEEN WHETHER A LINE
CAN UNZIP NORTHWARD DESPITE THE CIN THAT REMAINS IN PLACE. IF A
LINE CAN DEVELOP THERE...IT WILL PROVIDE THE BEST CHANCE AT AN
ISOLATED SEVERE REPORT BEFORE THE LINE EXITS INTO THE DAKOTAS.
THE SECONDARY WAVE IS STARTING TO DEVELOP A LINE FROM JUST SOUTH
OF RED LODGE DOWN TOWARD JACKSON WYOMING. TREND IN THE HRRR HAS
BEEN TO EVOLVE THIS LINE ACROSS BIG HORN COUNTY AND SOUTHEAST
MONTANA THROUGH THIS EVENING...WITH SOME STRONGER CELLS EMBEDDED.
MAIN THREATS WITH THIS LINE OF STORMS WILL LIKELY BE HEAVY
RAIN...FREQUENT LIGHTNING AND SMALL HAIL. WHILE WOULDNT RULE OUT
A SEVERE REPORT...ELEVATED NATURE OF THE CONVECTION BEHIND THE
SURFACE FRONT SHOULD HELP TO PRECLUDE ANY SEVERE ACTIVITY.
CYCLONIC FLOW WITH WEAK EMBEDDED SHORTWAVES WILL REMAIN IN PLACE
OVER THE FORECAST AREA THROUGH SUNDAY MORNING...THUS KEEPING AN
OVERALL WET FORECAST GOING THROUGH MID DAY SUNDAY. COULD SEE A
BREAK IN THE ACTIVITY BY SUNDAY AFTERNOON AND EVENING...BEFORE
MORE ISOLATED/SCATTERED SHOWERS DEVELOP ACROSS THE AREA MONDAY
AFTERNOON AS THE CYCLONIC FLOW REMAINS IN PLACE ALOFT.
TEMPERATURES THROUGH THIS PERIOD WILL REMAIN COOLER...WITH DAY
TIME HIGHS ONLY EXPECTED IN THE LOW 70S ON SUNDAY AND MONDAY.
CHURCH
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
EXTENDED FORECAST STARTS OFF QUIET FOR TUESDAY INTO WEDNESDAY AS MODELS
CONSISTENT WITH ZONAL DOWNSLOPE FLOW ACROSS THE AREA. CONDITIONS
BEGIN TO CHANGE LATE WEDNESDAY AS SYSTEM OVER WESTERN CANADA DROPS
SOUTH AND DEFLECTS THE FLOW OVER MONTANA TO THE SOUTHWEST
INCREASING THE CHANCES FOR AFTERNOON AND EVENING THUNDERSTORMS.
THE LATEST ECMWF AND CANADIAN SOLUTIONS DRAG THE BULK OF THE
PACIFIC SYSTEM THROUGH THE AREA ON THURSDAY WHILE THE GFS IS
SLOWER AND A BIT FURTHER NORTH WITH THIS FORCING AND THE BETTER
PRECIPITATION CHANCES. WEAK ENERGY AND GENERAL TROFINESS RESIDES
OVER THE AREA BEHIND THE SYSTEM INTO NEXT WEEKEND. SPLIT THE
DIFFERENCE BETWEEN THE MODELS ON THE TIMING OF STRONGEST FORCING
OVER THE AREA RESULTING IN THE HIGHEST PRECIPITATION CHANCES LATE
THURSDAY INTO FRIDAY...BUT IF ECMWF IS CORRECT THIS COULD BE A BIT
LATE. CONTINUED 20 TO 30 PERCENT PRECIPITATION CHANCES INTO THE
WEEKEND. TRENDED TEMPERATURES DOWN FROM WEDNESDAY INTO THE WEEKEND
WITH MID 70S WEDNESDAY DROPPING INTO THE UPPER 60S FOR THURSDAY
AND FRIDAY. CHAMBERS
&&
.AVIATION...
WIDESPREAD SHOWERS AND THUNDESTORMS WILL CONTINUE ACROSS THE
FORECAST AREA INTO THIS EVENING. THUNDERSTORM COVERAGE WILL
DECREASE OVERNIGHT TONIGHT BUT SCATTERED SHOWER ACTIVITY WILL
CONTINUE INTO TOMORROW MORNING. LOCAL MVFR CONDITIONS IN MODERATE
TO HEAVY RAIN CAN BE EXPECTED WITH THIS ACTIVITY. MOUNTAIN
OBSCURATION WILL BECOME MORE PERSISTENT THROUGH THE EVENING.
CHAMBERS
&&
.PRELIMINARY POINT TEMP/POPS...
SUN MON TUE WED THU FRI SAT
-----------------------------------------------------------
BIL 054/068 051/069 050/078 054/077 050/069 049/069 050/070
64/T 22/T 10/U 11/U 22/T 33/T 33/T
LVM 046/066 043/068 043/079 046/077 043/068 044/069 045/072
63/T 22/T 10/U 12/T 23/T 33/T 33/T
HDN 054/069 051/071 051/080 053/081 051/072 051/073 050/073
55/T 22/T 10/U 11/U 12/T 33/T 33/T
MLS 056/072 052/073 052/079 054/080 053/071 053/072 052/071
44/T 12/T 10/U 01/U 12/T 22/T 22/T
4BQ 055/066 051/070 051/080 053/083 052/072 051/073 051/072
65/T 23/T 10/U 01/U 22/T 33/T 22/T
BHK 054/071 049/070 049/077 051/080 050/073 049/070 049/069
63/T 13/T 10/U 12/T 22/T 22/T 22/T
SHR 052/065 047/070 046/080 050/083 049/073 048/075 048/074
55/T 22/T 10/U 11/U 12/T 33/T 33/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
116 PM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 335 AM CDT SAT AUG 30 2014
LOW CLOUDS TODAY AND TSTM CHANCES FOR SUNDAY/SUNDAY NIGHT (WITH
SOME SEVERE WEATHER POTENTIAL) ARE THE PRIMARY FORECAST CONCERNS.
TROUGH AXIS HAD FINALLY SHIFTED EAST OF THE AREA WITH MAIN AREA OF
PCPN EARLY THIS MORNING FROM SERN MN ACROSS ERN IA AND DOWN INTO MO.
A 70 KNOT JET MAX AT 300 MB WAS NEAR THE OR/CA BORDER AT 00Z...WHICH
WAS ASSOCIATED WITH THE NEXT UPSTREAM SHORTWAVE TROUGH. 12 HOUR
HEIGHT FALLS OF UP TO 50 METERS WERE NOTED OVER SRN BC CANADA AND
WEAKER HEIGHT FALLS EXTENDED DOWN INTO NRN CA/WRN NV. OUR AREA WILL
BE MUCH DRIER TODAY WITH SHORTWAVE RIDGING BETWEEN THE DEPARTING
SYSTEM TO OUR EAST AND THE APPROACHING SYSTEM TO OUR WEST. LOW
CLOUDS WERE OVER ERN SD AND WRN IA EARLY THIS MORNING. SOME OF THE
HIGH RESOLUTION MODELS...INCLUDING THE HRRR AND RAP SHOWED THESE
OVER THE NRN AND ERN PARTS OF THE FCST AREA THIS MORNING. WILL
GENERALLY FOLLOW THIS TREND...THEN LET THE CLOUDS BREAK UP A BIT
THIS AFTN. PREVIOUS FORECAST LOOKED GOOD AND WAS IN LINE WITH A
BLEND OF MOS...SO LOOK FOR HIGHS MAINLY AROUND 80 TO 85.
TONIGHT...CLEAR TO PARTLY CLOUDY SKIES SHOULD BE THE RULE MUCH OF
THE NIGHT WITH AN INCREASE EXPECTED OVER THE WRN PARTS OF NERN
NE LATE. MODELS ARE IN GENERAL AGREEMENT THAT THIS AREA COULD ALSO
SEE SOME TSTMS BY DAYBREAK WITH MID LEVEL MOISTURE AND LIFT. THESE
WOULD THEN LIKELY DEVELOP EWD WITH TIME THE REST OF THE DAY.
THE MAIN SHOW WILL PROBABLY WAIT UNTIL LATE AFTERNOON OR EARLY
EVENING AND BE MORE TIED TO LOW LEVEL CONVERGENCE ALONG THE
APPROACHING COLD FRONT. AGREE WITH SPC DAY 2 OTLK WHICH HAS ALL
OF OUR AREA IN A SLGT RISK. ML CAPE VALUES ARE EXPECTED TO REACH
3000 TO 4000 J/KG IN THE AFTN AND LINGER INTO THE EVENING. 0 TO
6 KM BULK SHEAR VECTORS IN COMBINATION WITH EXPECTED CAPE SHOULD
BE SUFFICIENT FOR STORM ORGANIZATION. INITIALLY DISCRETE STORMS
WILL LIKELY MERGE INTO ONE OR MORE CLUSTERS AND/OR A LINE. 21Z
SUNDAY TO 06Z MONDAY SEEMS TO BE THE MOST FAVORED TIME BASED ON
FORECAST SOUNDINGS AND OTHER CURRENT MODEL DATA. IN ADDITION TO
THE SEVERE THREAT...LOCALLY HEAVY RAIN IS PROBABLY GOING TO BE AN
ISSUE DUE TO THE RECENT ISSUES WITH SOME STREAMS/RIVERS.
STORMS COULD LINGER TOWARD 12Z MONDAY NEAR THE MO BORDER BUT THE
REST OF THE DAY SHOULD BE MAINLY DRY WITH HIGHS IN THE UPPER 70S
NORTH TO LOWER 80S SOUTH.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 335 AM CDT SAT AUG 30 2014
MODELS AGREE ON GENERAL PATTERN BUT HAVE SOME DIFFERENCES WITH
DETAILS. NORTHWEST FLOW AT 500 MB TUESDAY SHOULD BECOME MORE ZONAL
WEDNESDAY AND THEN BECOME SOUTHWEST AS A TROUGH DIGS ACROSS THE
PACIFIC NORTHWEST LATER IN THE WEEK. DID NOT FAVOR ANY ONE MODEL
IN THIS PERIOD. THE 00Z ECMWF WAS WETTER MONDAY NIGHT FOR MOST OF
THE AREA...WHILE THE GFS WAS WETTER TUESDAY NIGHT/WEDNESDAY IN
SERN NE/SWRN IA.
HIGHS SHOULD BE MOSTLY IN THE 80S WITH SOME LOWER 90S POSSIBLE
SRN ZONES THURSDAY. A SLIGHT COOL DOWN SEEMS POSSIBLE FRIDAY INTO
SATURDAY WITH A DECENT CHANCE FOR SHOWERS/THUNDERSTORMS AS ANOTHER
FRONTAL SYSTEM MOVES THROUGH THE REGION.
&&
.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 113 PM CDT SAT AUG 30 2014
STRATUS LAYER FINALLY BREAKING UP AT KOMA AT START OF FORECAST
PERIOD. VFR CONDITIONS EXPECTED AT ALL THREE SITES THROUGH THE
REMAINDER OF THE FORECAST IN ADVANCE OF APPROACHING COLD FRONT.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...MILLER
LONG TERM...MILLER
AVIATION...FOBERT
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1236 PM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT SAT AUG 30 2014
REMNANT CONVECTIVE DEBRIS WILL CONTINUE TO SLIDE SOUTHEASTWARD
ACROSS SW NEB THROUGH SUNRISE WHILE STRATUS CONTINUES TO DROP
SOUTHWARD ACROSS ERN SD. RAP LOW LEVEL RH PROGS WOULD SUGGEST THE
STRATUS WILL SAG TO NEAR THE NIOBRARA VALLEY BY 12-15Z OR SO AND THE
HRRR HAS LOW CLOUDS EVEN FURTHER SOUTH. HAVE ADJUSTED SKY COVER FOR
THAT. PREVIOUS FCST HAD MENTION OF FOG ALSO IN THE NERN ZONES AS A
RESULT OF PREVIOUS 24 HR RAINFALL AND BELIEVE THAT THIS WOULD ALSO
BE ALONG THE FRINGE OF LOWER CLOUDS WHICH IS A TYPICAL EVOLUTION
ANYWAY. SO HAVE LEFT THE MENTION OF FOG AS IT WAS...MORE PATCHY TWD
THE SWRN PORTION OF THE AREA...ALL OF WHICH SHOULD BURN OFF BY MID
MORNING. ON THE LARGER SCALE...A TRANSITORY UPPER RIDGE WILL
PROGRESS ACROSS THE AREA TODAY AS THE NRN STREAM REMAINS
ACTIVE...WITH LARGE SCALE SUBSIDENCE IN CONTROL THROUGH THE DAY.
NEXT LONG WAVE TROUGH IS DEVELOPING ACROSS THE PAC NW WITH A LEAD PV
ANOMALY MOVING QUICKLY ACROSS THE NRN ROCKIES TODAY. A LEE SIDE SFC
TROUGH WILL DEVELOP FROM WRN SD INTO THE TX PANHANDLE BY LATE
AFTERNOON AND THE RESPONSE WILL BE AN INCREASE OF SRLY WINDS AND
DEVELOPING THERMAL RIDGE ACROSS THE HIGH PLAINS. ON THE ERN EDGE OF
THE THERMAL RIDGE /WHICH WILL BE RETREATING NWD THROUGH THE DAY/
HIGHER DEW POINTS WILL EXIST. THERE IS WEAK CONVERGENCE ASSOCIATED
WITH THIS FEATURE AS IT RETREATS DURING THE DAY...BUT DEEP LAYER
LIFT DOES NOT LOOK EVIDENT. MAX TEMPS SHOULD CREEP A FEW DEGREES
HIGHER TODAY AS A RESULT OF THE DEVELOPING THERMAL RIDGE...MOST
NOTABLY IN THE SOUTHWEST AND EASTERN PANHANDLE.
ATTENTION THEN TURNS TO LOWERING HEIGHTS ACROSS THE NRN PLAINS SAT
NIGHT AND SUNDAY. LEAD PV ANOMALY /WHICH IS BEST DEFINED INITIALLY
BY 30.00Z GFS/ WILL APPROACH THE PANHANDLE BY LATE SAT
AFTERNOON...THOUGH WEAKENING AS IT MOVES INTO THE RIDGE POSITION.
CONVERGENCE ALONG THE LEE TROUGH IS WEAK INITIALLY BUT WILL LIKELY
PROVIDE ENOUGH LIFT ALONG WITH THE HIGHER TERRAIN FURTHER WEST TO
DEVELOP AT LEAST ISOLATED TSRA WHICH WILL MOVE EWD SAT EVE...THOUGH
LOW LEVELS WILL BE FAIRLY DRY AS SUGGESTED BY WRN FCST SOUNDINGS.
HIGH PLAINS NOCTURNAL LLJ DEVELOPS THROUGH SAT EVE WHICH WILL ADVECT
MID LEVEL INSTABILITY INTO THE CENTRAL PORTION OF THE STATE AND
SHOULD MAINTAIN ENOUGH DEEP LAYER LIFT TO SUPPORT ISOLATED TSRA INTO
THE WRN PORTION OF THE FCST AREA LATE EVE AND EARLY MORNING. NAM/GEM
AND GFS SUPPORT THIS THOUGH HIRES CAMS ARE NOT SO EAGER TO DEVELOP
PRECIP. GRIDS WILL INCLUDE ISOLATED TSRA MENTION...PROGRESSING
ACROSS THE AREA THROUGH SAT NIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 328 AM CDT SAT AUG 30 2014
12Z SUNDAY AND BEYOND. ZONAL UPPER LEVEL FLOW TO PREVAIL ACROSS
MUCH OF THE CONTIGUOUS 48 TO START OFF THE EXTENDED FORECAST
PERIOD...BUT THE PATTERN DOES SHIFT SLIGHTLY SOUTHWESTERLY ACROSS
THE HIGH PLAINS ON SUNDAY WITH THE APPROACH OF AN UPPER
TROPOSPHERIC NORTHERN ROCKIES SHORTWAVE. THE APPROACH OF THE
SHORTWAVE WILL ALLOW AN AREA OF SFC LOW PRESSURE AND ATTENDANT
BAROCLINIC ZONE TO MOVE EAST ACROSS THE REGION THROUGH THE DAY ON
SUNDAY...POTENTIALLY SETTING THE STAGE FOR AN ACTIVE SEVERE
WEATHER PATTERN ACROSS OUR EAST BY LATE AFTERNOON. GUIDANCE
CONTINUES TO FAVOR EAST OF A KLBF TO KANW LINE WHERE THERMAL
ADVECTION IS SHOWN AND CONVERGENCE ALONG THE BAROCLINIC ZONE WILL
BE MAXIMIZED. THE GFS...NAM...AND EC ALL SHOW CONVECTION FIRING IN
THIS AREA...SO GIVEN THE GOOD AGREEMENT OF NOT ONLY THE FINER
DETAILS BUT ALSO THE LARGER SCALE PATTERN...FELT THAT CONFIDENCE
WAS ENOUGH TO INTRODUCE LIKELY/S INTO THE FORECAST ACROSS OUR FAR
EAST /EAST OF A MAYWOOD TO NAPER LINE/...WITH SOLID CHANCE POPS
/40-50%/ FOR LOCATIONS EAST OF THE KANW TO KLBF LINE SUNDAY
AFTERNOON. THE UPPER TROPOSPHERIC FLOW REMAINS FAIRLY
PROGRESSIVE...SO STORMS SHOULD BE LARGELY REMOVED OF THE FORECAST
AREA BY 06Z MONDAY. SFC TD/S ARE PROJECTED TO REBOUND BACK INTO
THE LOWER TO MID 60S ACROSS OUR EAST AND WHEN COMBINED WITH STEEP
LOWER TO MID LEVEL LAPSE RATES WHICH PROMOTE SB POTENTIAL ENERGY
IN EXCESS OF 2500 J/KG...ROBUST UPDRAFTS ARE ANTICIPATED. DEEP
LAYER SHEAR IS SHOWN TO BE QUITE FAVORABLE FOR SEVERE
WEATHER...WITH THE MODELS PEGGING UPWARDS OF 40-50KTS 0-6KM BULK
SHEAR...LARGE HAIL WILL BE POSSIBLE. THE UPDRAFTS SHOULD QUICKLY
CONGEAL ALONG THE BAROCLINIC ZONE INTO A QUASI-LINEAR CONVECTIVE
BAND WHICH WOULD PROMOTE DAMAGING THUNDERSTORM WIND INTO THE
EVENING.
INTO EARLY NEXT WEEK...THERE REMAINS SOME DISCREPANCIES ON THE
TIMING OF THE EXITING TROUGH...MOST NOTABLY...THE EC RETAINS A PIECE
OF ENERGY WEST OF THE FORECAST AREA...BUT BRINGS IT THROUGH MONDAY
NIGHT. THE EC GENERATES LIGHT QPF ACROSS MUCH OF THE FORECAST AREA
DURING THIS TIME PERIOD. THE GFS IN COMPARISON IS DRY AND LACKS
MUCH OF THE EVIDENCE SUPPORTING THIS ADDITIONAL TROPOSPHERIC
PERTURBATION. GIVEN THE UNCERTAINTY...WENT AHEAD AND SCALED BACK
POPS MONDAY EVENING INTO EARLY TUESDAY...BUT WILL KEEP A SLIGHT
MENTION GOING.
BEYOND EARLY TUESDAY...THE CR ALLBLEND PROCEDURE PROJECTED A DRY
FORECAST THROUGH THURSDAY OF NEXT WEEK...AND THERE ARE NO ARGUMENTS
HERE AS AN OVERALL LACK OF OMEGA WOULD BE ANTICIPATED AS THE STORM
TRACK SHIFTS NORTH AND LOW AMPLITUDE RIDGING ENCOMPASSES MUCH OF THE
CONUS. LATE IN THE EXTENDED THERE MAY BE ANOTHER SHORTWAVE
IMPACTING THE CENTRAL PLAINS...HOWEVER THE MODELS SEEM TO BE BACKING
OFF THIS SOLUTION A BIT...FOCUSING THE BEST POTENTIAL WELL NORTH OF
THE CWA. WILL KEEP THE PROCEDURE UNCHANGED FOR NOW.
NOT ANTICIPATING ANY VIOLENT TEMPERATURE CHANGES THROUGH THE
EXTENDED PERIODS...BUT WITH EACH FRONTAL PASSAGE...TEMPERATURES WILL
MODERATE SOME. THE WARMEST DAY APPEARS TO COME MID-WEEK...AS HIGHS
ON WEDNESDAY ARE FORECAST TO APPROACH THE UPPER 80S TO LOWER 90S FOR
MOST LOCATIONS. OTHERWISE HIGHS IN THE 70S TO LOW TO MID 80S SHOULD
PREVAIL FOR MOST DAYS. LOWS IN THE 50S AND 60S SEEM TO BE THE NORM
OVER THE NEXT 7 DAYS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1234 PM CDT SAT AUG 30 2014
VFR CONDITIONS WILL PREVAIL ACROSS WESTERN AND NORTH CENTRAL
NEBRASKA THROUGH THE NEXT 24 HOURS. ISOLATED SHOWERS AND STORMS
MAY MOVE EAST OUT OF THE PANHANDLE AFTER 3Z TONIGHT...HOWEVER
LIMITED SPATIAL COVERAGE AND LOW FORECASTER CONFIDENCE DO NOT
WARRANT ANY MENTION OF -TSRA IN THE TAFS AT THIS TIME. A COLD
FRONT WILL MOVE THROUGH THE AREA TOMORROW MORNING...SWITCHING THE
WIND DIRECTION TO THE NORTHWEST.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JWS
LONG TERM...JACOBS
AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
652 PM EDT SAT AUG 30 2014
.SYNOPSIS...
EXPECT AN INCREASING CHANCE OF SHOWERS AND A FEW THUNDERSTORMS
TONIGHT AND ESPECIALLY ON SUNDAY AS WEAK LOW PRESSURE CROSSES THE
REGION. AFTER A MAINLY DRY DAY ON MONDAY...SHOWERS AND
THUNDERSTORMS RETURN IN EARNEST BY TUESDAY AS A MORE DEFINITIVE
SURFACE FRONT MAKES ITS WAY INTO THE REGION. TEMPERATURES WILL
REMAIN WARM THROUGH TUESDAY...THEN COOL BACK TO LATE SUMMER
SEASONAL NORMALS BEHIND THE FRONT BY MID TO LATE WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
AS OF 643 PM EDT SATURDAY...EARLY UPDATE TO FCST THIS EVENING TO
INCREASE POPS ACRS THE SLV. CRNT RADAR SHOWS A CLUSTER OF SHOWERS
WITH EMBEDDED THUNDERSTORMS DEVELOPING OVER CENTRAL LAKE ONTARIO.
USING THE TIME OF ARRIVAL TOOL...PLACES THIS ACTIVITY ACRS EXTREME
SOUTHWEST ST LAWRENCE COUNTY AROUND 00Z AND INTO THE CENTRAL
PORTION OF THE COUNTY BY 01Z. LATEST 21Z HRRR MODELS SEEMS TO BE
HANDLING PRECIP THE BEST AND SHOWS THIS AREA QUICKLY TRACKING
NORTHEAST INTO THE SLV...BUT WEAKENING AS BEST INSTABILITY IS
LOCATED ACRS WESTERN NY. WL MENTION CHC POPS WITH THIS SECONDARY
WARM FRNT AND ASSOCIATED LLVL JET. THESE SHOWERS WL RESULT IN A
JUMP IN SFC DWPTS...ESPECIALLY ACRS THE SLV/NORTHERN NY
TONIGHT...WITH THIS BOUNDARY LIFTING INTO THE CPV AFT 06Z.
THINKING ADDITIONAL SHOWERS COULD DEVELOP AFT MIDNIGHT ACRS
NORTHERN NY AND MOVE INTO THE CPV TWD 09Z. THIS IS ALL COVERED IN
CRNT FCST WITH CHC POPS...INCREASING TO LIKELY TOWARD DAY BREAK.
INSTABILITY IS MARGINAL AND ELEVATED ASSOCIATED WITH LLVL JET...SO
ONLY SCHC FOR THUNDER OVERNIGHT INTO EARLY SUNDAY MORNING. TEMPS
WL HOLD IN THE U50S NEK TO U60S SLV/CPV...ASSOCIATED WITH
INCREASED DWPTS AND GUSTY SOUTHERLY WINDS. THE HUMIDITY WL CONT TO
INCREASE OVERNIGHT INTO SUNDAY...ESPECIALLY IN THE CPV. EXPECT IT
TO FEEL PRETTY HUMID BY MIDDAY SUNDAY...ACRS MOST OF THE REGION.
PREVIOUS DISCUSSION FOLLOWS...
SOUTHERLY FLOW WILL CONTINUE THIS EVENING/TONIGHT AS HIGH PRESSURE
DEPARTS OFFSHORE AND A DAMPENING SFC TO MID LEVEL TROUGH PUSHES
EAST FROM THE GREAT LAKES/OHIO VALLEY. SCATTERED SHOWERS AND/OR
ISOLATED STORMS WILL BE POSSIBLE LATER THIS EVENING AND
TONIGHT...ESPECIALLY ACROSS OUR NRN NY COUNTIES WHERE SLIGHT H5
HEIGHT FALLS...INCREASING MOISTURE RETURN AND SOME MID LEVEL
INSTABILITY WILL BE PRESENT. TEMPERATURES TO HOLD ON THE MILD SIDE
(60S) AS CLOUDS SLOWLY INCREASE THROUGH TIME...ESPECIALLY IN THE
ST LAWRENCE AND CHAMPLAIN VALLEYS WHERE NOCTURNAL SOUTHERLY LLJ
DEVELOPMENT IS EXPECTED NEAR THE 925 MB LEVEL.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
AS OF 330 PM EDT SATURDAY...MOST INCLEMENT WEATHER IN THE SHORT
TERM THEN OCCURS ON SUNDAY INTO SUNDAY EVENING AS AFOREMENTIONED
TROUGH SWINGS THROUGH THE AREA ALONG WITH NUMEROUS SHOWERS/STORMS.
NEGLIGIBLE BAROCLINICITY ACROSS THE BOUNDARY COMBINED WITH PLENTY
OF CLOUDS AND LIMITED INSTABILITY SHOULD KEEP ANY ENHANCED SVR
THREAT AT A MINIMUM...BUT WE COULD SEE A FEW STRONGER CELLS ACROSS
OUR FAR SRN VT COUNTIES WHERE SOME MORNING SUN WILL BE POSSIBLE.
GUSTY WINDS WOULD BE THE PRIMARY THREAT IF ANYTHING WOULD DEVELOP.
OTHERWISE EXPECT A GENERALLY CLOUDY AND OCCASIONALLY WET DAY AS
SHOWERS/SCT GARDEN-VARIETY STORMS TRAVERSE THE REGION. NARROW PWAT
AXIS OF 1.7-1.9 INCHES WILL EXIST ALONG AND JUST AHEAD OF THE
BOUNDARY SO SOME BRIEF HEAVIER DOWNPOURS ARE CERTAINLY POSSIBLE.
HOWEVER MEAN STORM MOVEMENT OF 15 TO 20 MPH SHOULD LIMIT ANY
HYDROLOGICAL CONCERNS. HIGHS MAINLY IN THE 70S GIVEN THE AMPLE
CLOUDS.
EVENING SHOWERS/STORMS THEN EXIT EAST THROUGH THE EVENING HOURS ON
SUNDAY AS TROUGH CLEARS THE AREA LEAVING VARIABLY CLOUDY SKIES
OVERNIGHT. COULD SEE SOME PATCHY FOG HERE AND THERE BUT LOW LEVEL
WIND FIELDS HIGH ENOUGH THAT IT SHOULD BE MORE CONFINED TO MOST
FAVORED CLIMATOLOGICAL AREAS. AS MENTIONED ABOVE...LITTLE AIRMASS
CHANGE BEHIND THE BOUNDARY...SO LOWS GENERALLY IN THE 60S
EXPECTED...PERHAPS A FEW UPPER 50S IN COOLER NRN MTN LOCALES.
BY MONDAY WEAK SHORTWAVE RIDGING DEVELOPS BETWEEN DEPARTING TROUGH
AND A MORE SUBSTANTIAL UPPER TROUGH DIGGING ACROSS THE GREAT LAKES
STATES TO OUR WEST. CAN`T COMPLETELY RULE OUT AN ISOLATED
SHOWER/STORM JUST ABOUT ANYWHERE WITH SOME LINGERING MOISTURE AND
PBL INSTABILITY OF 200-600 J/KG...BUT MOST LOCALES SHOULD REMAIN
LARGELY DRY WITH LACK OF LARGE-SCALE FORCING. BLENDED 18Z 925MB
THERMAL PROFILES SUGGEST HIGHS FROM 77 TO 83 OR SO UNDER PARTIAL
SUNSHINE...WARMEST IN THE BROADER VALLEYS.
THEN PARTLY CLOUDY AND CONTINUED MAINLY DRY MONDAY NIGHT AS
SOUTHERLY FLOW SLOWLY INCREASES ONCE AGAIN AHEAD OF APPROACHING
UPPER TROUGH AND ATTENDANT SFC BOUNDARY TO OUR WEST. WILL CONTINUE
PRIOR IDEA OF LOWER CHANCES FOR SHOWERS/STORMS ACROSS OUR
WESTERNMOST NY COUNTIES OVERNIGHT IN CLOSER PROXIMITY TO THE
BOUNDARY AND BETTER DYNAMICAL FORCING. MAINLY DRY FURTHER EAST INTO
VERMONT HOWEVER. TEMPERATURES REMAIN ON THE MILD SIDE...GENERALLY IN
THE 60S.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 341 PM EDT SATURDAY...THIS LONG TERM PERIOD LOOKS VERY CONSISTENT
TO PREVIOUS FCST.
THE MAIN WEATHER CONCERN DURING THIS LONG TERM PERIOD WILL BE TUESDAY
AND TUESDAY NIGHT. UPPER LEVEL TROUGH AND ITS ASSOCIATED COLD
FRONT WILL BE MOVING INTO THE AREA DURING THE AFTERNOON AND
EVENING HOURS. AHEAD OF THE FRONT...ABOVE NORMAL TEMPERATURES ARE
EXPECTED WITH HIGHS IN THE 80S AND COMBINED WITH INCREASING DEW
POINTS...SUFFICIENT INSTABILITY WILL DEVELOP OVER THE AREA AHEAD
OF THE FRONT. DEEP LAYER SHEAR WILL ALSO BE INCREASING OVER THIS
AREA OF DEVELOPING INSTABILITY. ALL OF THIS SUGGESTS THE POTENTIAL
FOR THUNDERSTORMS...SOME OF WHICH COULD BE STRONG OR SEVERE. THUS
WILL HAVE TO KEEP AN EYE ON THIS SYSTEM.
THEREAFTER...FRONT EXITS THE AREA BY EARLY WED MRNG AND UPPER LEVEL
FLOW FOR THE REMAINDER OF THE WEEK QUICKLY RETURNS TO ZONAL FLOW ON
NORTHERN PERIPERHY OF SOUTHEAST CONUS RIDGE. THEREFORE...PRETTY MUCH
DRIER AIR BUT AOA SEASONABLE TEMPS CONTINUE BEFORE ANOTHER NRN
STREAM SHORTWAVE...THIS ONE FURTHER NORTH...MOVES ACROSS QUEBEC
WITH A SURFACE FRONT IN THE FRI NGT-SAT TIMEFRAME. HIGH TEMPS IN THE
M-U70S TO L80S.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
THROUGH 18Z SUNDAY...OVERALL LOOKING AT VFR CONDITIONS THROUGH
MOST OFTHE PERIOD. MAINLY MID AND HIGH LEVEL CLOUDS THROUGH THE
EVENING...THEN CEILINGS BEGIN TO LOWER TONIGHT WITH BROKEN TO
OVERCAST CEILINGS AROUND 5000 FEET ARD/AFT 06Z SUNDAY SPREADING EAST.
THERE WILL ALSO BE SOME LIGHT SHOWERS MOVING FROM WEST TO EAST
BETWEEN 06Z AND 12Z...BUT VISIBILITIES WILL REMAIN UNRESTRICTED.
SHOWERS BECOME MORE NUMEROUS AND LOCALLY HEAVY DUE TO HIGH
PRECIPITABLE WATERS THUS ANY SHOWERS MAY HAVE BRIEF MVFR-IFR IN
VSBY DUE TO RAINFALL INTENSITY WITH MVFR CIGS LIKELY FOR MOST ON SUNDAY.
WINDS WILL BE LIGHTER THAN TODAY...SSW 10 KTS OR SO.
OUTLOOK 18Z SUNDAY THROUGH WEDNESDAY...
18Z SUNDAY ONWARD...MAINLY VFR, THOUGH MVFR/BRIEF IFR IN
SCATTERED SHOWERS AND THUNDERSTORMS THAT WILL BE MOST NUMEROUS
SUNDAY AND PERHAPS AGAIN LATE TUESDAY.
&&
.MARINE...
AS OF 300 PM EDT SATURDAY...SOUTH WINDS OF 15 TO 25 KNOTS WILL
CONTINUE THROUGH THE REMAINDER OF TODAY...TONIGHT...AND INTO
SUNDAY MORNING. GUSTS WILL REACH 30 KNOTS AT TIMES. THUS A LAKE
WIND ADVISORY REMAINS IN EFFECT. THESE WINDS WILL CREATE WAVES OF
2 TO 4 FEET...WITH THE HIGHEST WAVES IN THE OPEN WATERS OF THE
CENTRAL AND NORTHERN PORTIONS OF THE LAKE. BY SUNDAY
AFTERNOON...SOUTH WINDS WILL TAPER OFF TO 10 TO 20 KNOTS AND WAVES
WILL SUBSIDE TO 1 TO 3 FEET. WIDESPREAD SHOWERS AND THUNDERSTORMS
WILL ALSO DEVELOP ON SUNDAY.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...JMG
NEAR TERM...JMG/TABER
SHORT TERM...JMG
LONG TERM...EVENSON/SLW
AVIATION...EVENSON/SLW
MARINE...WFO BTV
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
249 PM EDT SAT AUG 30 2014
.SHORT TERM...(TONIGHT THROUGH MONDAY)...GULF MOISTURE CONTINUES TO
STREAM NORTHWARD FROM THE WESTERN GULF OF MEXICO THIS AFTERNOON.
AIR MASS IS BECOMING SLIGHTLY TO MODERATELY UNSTABLE WITH SPOTTY
CONVECTION POPPING OVER SE TN...AND MORE SO TO OUR SW OVER NE AL.
I ADJUSTED THE SHORT TERM GRIDS FOR LATE AFTERNOON AND THIS EVENING
IN LINE WITH THE SIMILAR HRRR AND RAP MODELS...WHICH SUPPORTS
LIKELY POPS OVER WRN AREAS. THE SHORTWAVE TROUGH MOVES EAST ACROSS
THE WRN GREAT LAKES AND OHIO VALLEY REGION OVERNIGHT...WHICH SHOULD
KEEP HIGHER POPS IN ORDER AFTER MIDNIGHT ACROSS OUR NRN PLATEAU AND
EXTREME WRN SW VA COUNTIES.
FOR SUNDAY...STAYED WITH OUR LOW END OF LIKELY POPS...WHICH ARE
HIGHER THAN 12Z MOS GUIDANCE...SINCE THE SRN END OF THE UPPER
TROUGH WILL BE PASSING EAST ACROSS THE TN VALLEY AND SRN
APPALACHIANS DURING PEAK HEATING. LOWERED POPS FROM THE WEST
SUNDAY NIGHT WITH PASSAGE OF THE TROUGH AXIS. MONDAY ALSO SHAPING
UP DRIER THAN PREVIOUS GRIDS...SO CUT POPS BACK TO 20 TO 30
PERCENT...AND PUSHED MAX TEMPS BACK UP TO THE SIMILAR UPR 80S TO
LWR 90S FROM 12Z MOS. OTHERWISE...12Z NAM AND GFS MOS TEMPS WERE IN
GENERAL AGREEMENT AND CLOSELY FOLLOWED.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)...NOT MUCH FOCUS FOR
CONVECTION THROUGHOUT THE LONG TERM PERIOD OTHER THAN INTENSE SOLAR
HEATING AND OROGRAPHIC LIFT ON THE MAJOR TERRAIN FEATURES.
HOWEVER...THERE WILL BE SOME WEAK SHORT WAVE ENERGY MAKING ITS WAY
ACROSS THE NORTHEASTERN QUARTER OF THE NATION LATER TUESDAY INTO
WEDNESDAY AND THIS CONFIGURATION MAY COAX A WEAK COOL FRONT INTO THE
SOUTHERN APPALACHIAN REGION WEDNESDAY THROUGH FRIDAY. THIS BOUNDARY
MAY ALLOW FOR A SLIGHT INCREASE IN PROBABILITY OF PRECIPITATION
MAINLY ON WEDNESDAY IF IT CAN MAKE IT FAR ENOUGH SOUTH. OTHERWISE
GENERALLY KEPT POPS AROUND 20-25 PERCENT AS UPPER RIDGING HANGS
AROUND THE SOUTHEASTERN U.S. TRENDED MAX TEMPS A LITTLE CLOSER TO
SUGGESTED HIGHS FOR THE UPCOMING WEEK AS THE ANNUAL LATE SUMMER LAG
IN HEATING DUE TO LONG WAVE RE-RADIATION FINALLY CATCHES UP TO US.
STAYED PRETTY CLOSE TO MINS THROUGH THE PERIOD.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 71 87 71 93 / 60 60 40 20
KNOXVILLE MCGHEE TYSON AIRPORT, TN 69 86 70 91 / 50 60 30 20
OAK RIDGE, TN 70 84 69 91 / 60 60 40 20
TRI CITIES AIRPORT, TN 66 87 65 87 / 50 60 40 20
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
TG
AREA FORECAST DISCUSSION
NWS PORTLAND OR
300 PM PDT SAT AUG 30 2014
.SYNOPSIS...COOLER WESTERLY FLOW ALOFT PREVAILS THROUGH THIS
WEEKEND..WITH A SERIES OF WEAK SURFACE FRONTS. THIS WILL BRING
PLENTY OF CLOUDS AND COOLER AIR TO THE REGION...ALONG WITH PERIODIC
RAIN SHOWERS. THE BEST CHANCES OF SHOWERS WILL BE THIS AFTERNOON AND
EVENING. WEAK RIDGING TRIES TO BUILD BACK INTO THE PACIFIC
MONDAY...BEFORE A DEEPER TROUGH MOVES OVER THE AREA TUESDAY THROUGH
THE END OF THE WEEK.
&&
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT...
A DISCONNECTED LINE OF MODERATE SHOWERS HAS DEVELOPED ALONG A WEAK
FRONT CURRENTLY MOVING ACROSS THE VALLEY. CURRENT ORIENTATION OF THE
JET STREAM PUTS US IN THE AREA OF FAVORABLE FORCING IN THE LEFT EXIT
REGION WHICH HAS HELPED TO PRODUCE STRONGER SHOWERS THIS AFTERNOON
AND EVEN A LONE LIGHTNING STRIKE IN NORTHERN MARION COUNTY AROUND 145
PM. AS EXPECTED...RAIN HAS MOSTLY CLEARED OUT ON THE COAST BEHIND THE
FRONT WITH THE EXCEPTION OF A BAND OF LIGHT SHOWERS NEAR NEWPORT
WHICH MAY BE A SIDE EFFECT OF COLOCATION WITH THE JET STREAK. CLOUDS
WILL LINGER BEHIND THE FRONT BUT THERE SHOULD BE ENOUGH BREAKS
OVERNIGHT TO COOL DOWN A COUPLE OF DEGREES MORE THAN LAST NIGHT.
ANOTHER WEAK FRONT WILL MOVE ACROSS THE AREA SUNDAY. THE CHANCE FOR
RAIN IS WEAKER WITH THIS SYSTEM AS THE UPPER JET SHIFTS
NORTHWARD...REDUCING ATMOSPHERIC LIFT. THE PRECIPITATION ON
SUNDAY WILL BE VERY LIGHT AND BE RESTRICTED TO THE NORTHERNMOST PART
OF THE FORECAST AREA WITH MODELS CONTINUING TO TREND DOWNWARD WITH
POPS. AN UPPER RIDGE WILL BUILD MONDAY...BUT THE MODELS HAVE BEEN
BACKING OFF ON THE STRENGTH OF THE RIDGE AND EXPECT ANOTHER WEAK
FRONT TO CLIP THE NORTHERN AREAS MONDAY AFTERNOON AND EVENING.
RIDGING TRIES TO ESTABLISH ITSELF ON TUESDAY BUT AN UPPER LEVEL
TROUGH STARTS TO DIG INTO SE BRITISH COLUMBIA. ALTHOUGH WEAK...AN
ARGUMENT COULD BE MADE FOR SOME ENHANCED FORCING DUE TO A WEAK JET
STREAK MOVING INTO NW WASHINGTON SO OVERALL DECREASED POPS TUESDAY
BUT KEPT THEM MENTIONABLE ACROSS THE SW WASHINGTON PART OF THE
FORECAST AREA. BOWEN/TJ
.LONG TERM...THE MODELS CONTINUE TO HINT AT A TROUGH MOVING INTO THE
PACIFIC NORTHWEST ON TUESDAY. THIS TROUGH LOOKS TO STICK AROUND
THROUGH THE END OF NEXT WEEK. STILL KEEPING A SLIGHT CHANCE OF
SHOWERS IN THE FORECAST THROUGH THURSDAY FOR THE NORTHERN PORTIONS
OF THE CWA. TEMPERATURES WILL TREND TOWARDS SEASONAL NORMALS. LATE
NEXT WEEK THE MODELS CONTINUE TO TRY TO DEVELOP A CUTOFF
LOW...HOWEVER...DIFFERENCES BETWEEN THE VARIOUS MODELS AND MODEL
RUNS HAVE CREATED A LOT OF UNCERTAINTY. STILL LEANING TOWARDS IT
BEING DRIER AND SLIGHTLY WARMER FOR NEXT WEEKEND.
&&
.AVIATION...LIGHT SHOWERS WILL CONTINUE THROUGH THIS
EVENING...THEN GRADUALLY DECREASE FROM SOUTH TO NORTH. MOSTLY A
MIX OF MVFR AND VFR CONDITIONS INLAND...WITH IFR CONDITIONS
LIKELY IN SHOWERS. MOIST ONSHORE FLOW PERSISTS OVERNIGHT...LIKELY
BRINGING SOME 2000-2500 FT CIGS NEAR SUNRISE EARLY SUNDAY AM ALONG
THE LOWER COLUMBIA RIVER. OTHERWISE...MOST INLAND SITES WILL
REMAIN VFR WITH CIGS AROUND 5000 FT. COASTAL SITES WILL REMAIN
MVFR AND IFR THROUGH SUNDAY AM.
KPDX AND APPROACHES...MIX OF MVFR AND VFR CONDITIONS WITH CIGS
BETWEEN 2500-3500 FT. EXPECT LOWER CONDITIONS IN SHOWERS THROUGH
04-06Z SUNDAY. A FEW 2000 FT CIGS ARE EXPECTED AGAIN FROM 14-17Z
SUNDAY. /27
&&
.MARINE...AFTER A WEAK FRONTAL PASSAGE EARLIER TODAY...THE NEXT
STRONGER FRONT MOVES ACROSS THE COASTAL WATERS LATE SUNDAY. MODELS
SHOW LIGHT SW WINDS THROUGH SUNDAY...BEFORE BACKING TO THE NW BY
MONDAY. THE SEAS WILL COMPRISE OF A SMALL SW SWELL OF 1 TO 2
FEET AT AROUND 15 SECONDS AND A NORTHWEST FRESH SWELL FROM THE
GULF OF ALASKA AROUND 9 TO 10 SECONDS. LIGHT WIND WAVES THE NEXT
COUPLE OF DAYS. A NW SWELL WILL BUILD TONIGHT AND PEAK AROUND 6
FEET ON SUNDAY. HIGH PRESSURE WILL REBUILD MONDAY NIGHT AND
TUESDAY AND PERSISTENT NORTHERLY WINDS WILL RETURN TO THE WATERS.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...NONE.
&&
$$
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.
[top]
Area Forecast Discussion
National Weather Service Spokane WA
245 PM PDT SAT AUG 30 2014
.SYNOPSIS...
The Labor Day weekend will be cooler than normal, with locally
breezy conditions. Aside from isolated showers, the majority of
the Inland Northwest will remain dry. A continued cool pattern is
expected through the middle of next week, with the best chance for
showers and thunderstorms Wednesday. Relatively warmer, drier
weather is forecast late next week.
&&
.DISCUSSION...
Tonight and Sunday: A weak shortwave disturbance is bringing
isolated to scattered showers across the region. This shower
activity will continue to track east across the southern half of
the forecast area, generally along and south of Highway 2. This
will continue this evening and eventually move into the Idaho
panhandle. Oddly enough, the location of persistent showers is in
the area that models forecast to be in between the split flow of
energy. GFS/EC/NAM/SREF all show split flow with the bulk of the
shortwave energy either along our northern border or across
northern Oregon. The 15Z HRRR had a very good handle on the precip
but later runs showed the same split flow of other models. The
evening forecast is based on the 15Z HRRR which remains on track.
Thunder chances remain rather low but we might see a strike or two
across the extreme southeast corner of the forecast area this
evening. Overnight and into Sunday the Idaho panhandle will see
continued shower activity as westerly flow enhances ascent. Breezy
winds will continue tonight which will keep overnight lows from
bottoming out. If the sheltered northern valleys clear out at all
tonight there could be a few spots approaching the freezing mark.
Expect mainly dry conditions for the low lands Sunday with high
temperatures in the 70s. Isolated mountain showers will linger
over the Idaho panhandle but instability will be marginal for
thunder. /Kelch
Sunday Night through Tuesday: There are no notable changes to the
previous fcst, centering our focus on gusty winds near the
Cascades as well as pcpn chances. Rising hts aloft Sunday night
and Monday in NW steering flow will lead to stabilization aloft as
the jet axis translates slowly NE ahead of the significant upper
trough and mainly dry cold front across Srn BC Tuesday. Given the
lack of sfc-based and nocturnal elevated instability, we don`t
have much of a chance of pcpn in the fcst for any zone...and have
limited these chances to the Cascades and NE Wa and N Idaho
Panhandle mtns Sunday night and late Tuesday. However, pressure
gradients will increase ahead of the aforementioned trough and
help to keep gusty winds in the fcst. bz
Tuesday night through Saturday: A few showers and cool conditions
mark the beginning of this period, followed by a warming and
drying trend. A trough of low pressure migrates east-southeast
across the region Tuesday night to Wednesday night. A weak
deformation axis sagging in from the north, coupled with the lift
and instability associated with the trough, will bring shower
chances to the Cascades and northern counties. Some showers may
develop as far south as the Highway 2/I-90 corridor, from the
Waterville Plateau eastward, Wednesday afternoon/evening. As for
thunder prospects, I wouldn`t rule out some mixed with the
showers overnight into Wednesday morning, particularly toward the
northeast WA and north ID mountains where an area of moderately
unstable high level total totals values are depicted. However the
better thunderstorm threat comes Wednesday afternoon and evening
with increased SBCAPE. Overnight Wednesday the main trough shifts
east, taking the better instability and shower threat with it.
From Thursday to Saturday model agreement falters some. However,
loose agreement suggests a baggy trough over the western U.S. and
the Inland NW in a north to northwesterly flow. Weak mid-level
impulses in that flow and at least a suggestion of afternoon
instability toward the northern Rockies will keep shower chances
alive over the ID Panhandle. Otherwise the latter part of next
week looks dry, with just a few clouds. /J. Cote`
&&
.AVIATION...
18Z TAFS: VFR conditions expected through 18Z Sunday. A couple of
weak weather disturbances today will produce mainly mountain
showers. Breezy conditions will develop by early afternoon in the
post frontal air mass. Models are hinting at some low level
moisture advection across southeastern WA tonight. This is
expected to produce some mid level cloud cover across eastern WA
and showers ongoing over the ID Panhandle. This should not impact TAF
sites although KCOE and KPUW may see some vicinity showers 06Z-12Z
Sunday. /EK
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 52 71 51 75 49 76 / 20 10 10 0 0 0
Coeur d`Alene 50 69 47 74 46 75 / 20 10 10 0 0 0
Pullman 48 70 45 74 43 77 / 20 10 10 0 0 0
Lewiston 56 77 55 81 54 84 / 20 10 10 0 0 0
Colville 46 75 43 78 44 78 / 10 10 10 10 10 10
Sandpoint 46 68 43 72 45 73 / 20 20 20 10 10 10
Kellogg 49 65 47 69 47 71 / 30 30 10 10 10 0
Moses Lake 52 78 50 81 51 81 / 20 0 0 0 0 0
Wenatchee 57 77 56 80 56 80 / 20 0 0 0 0 0
Omak 52 78 51 81 52 80 / 10 0 10 0 0 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1248 PM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 321 AM CDT SAT AUG 30 2014
MAIN FORECAST CONCERN IS WITH THE RAIN CHANCES TODAY AND FROM
SUNDAY NIGHT INTO MONDAY.
LOCAL AND REGIONAL RADARS SHOWING A LARGE AREA OF RAIN LIFTING
NORTHEAST ACROSS EASTERN MINNESOTA AND MUCH OF WISCONSIN. SOME
TRAILING RAIN STILL BACK ACROSS EASTERN IOWA.
EXPECT THE RAIN TO CONTINUE LIFTING NORTHEAST THIS MORNING AS THE
SURFACE LOW JUST ENTERING WESTERN WISCONSIN ALSO CONTINUES TO MOVE
NORTHEAST IN CONJUNCTION WITH THE UPPER LEVEL TROUGH. THE 30.04Z
HRRR SEEMS TO HAVE A DECENT HANDLE ON THE ONGOING RAIN AND SHOWS
THE BACK EDGE ALONG THE MISSISSIPPI RIVER BY 12Z WITH MOST OF THE
AREA DRY BY 18Z. THIS IS VERY SIMILAR TO WHAT THE 30.00Z HI-RES
ARW AND NMM SHOW AND WILL PLAN TO TREND THE RAIN CHANCES IN THIS
DIRECTION. THE QUESTION THEN BECOMES IF ADDITIONAL ACTIVITY WILL
DEVELOP THIS AFTERNOON. THE 30.00Z NAM AND GFS BOTH BRING A
TRAILING SHORT WAVE TROUGH ACROSS THE AREA THIS AFTERNOON. IT DOES
APPEAR IN THE WATER VAPOR IMAGERY THAT THIS WAVE DOES EXIST AND IS
OVER EASTERN SOUTH DAKOTA. HOWEVER...THE WATER VAPOR IMAGERY ALSO
SHOWS A LOT OF DRY AIR IN PLACE BEHIND THE DEPARTING SHORT WAVE
TROUGH AND THE CONCERN BECOMES WHETHER THIS SECONDARY SHORT WAVE
TROUGH WILL HAVE ENOUGH FORCING TO CAUSE SOME ADDITIONAL
DEVELOPMENT. THE HRRR IS SUGGESTING THAT SOME COULD START TO FORM
EARLY IN THE AFTERNOON WHICH IS SIMILAR TO THE NAM AND GFS WHILE
THE ARW AND NMM REMAIN DRY THROUGH THE AFTERNOON. WITH ALL THE DRY
AIR...TEND TO FEEL THE ARW AND NMM HAVE THE MORE CORRECT SOLUTION
BUT WILL HOLD ONTO A SMALL RAIN CHANCE JUST IN CASE SOMETHING DOES
POP UP.
AFTER SOME WEAK UPPER LEVEL RIDGING MOVES OVER THE UPPER MIDWEST
TONIGHT AND SUNDAY...THE NEXT SYSTEM WILL TAKE AIM AT THE REGION.
WATER VAPOR IMAGERY ALREADY SHOWS IT APPROACHING THE PACIFIC
NORTHWEST COAST AND IT IS EXPECTED TO MOVE QUICKLY ACROSS THE
NORTHERN ROCKIES AND ACROSS THE UPPER MIDWEST SUNDAY NIGHT AND
MONDAY. THE GFS AND 30.00Z ECMWF BOTH CONTINUE TO SHOW THIS SYSTEM
PRODUCING MODERATE TO STRONG PV ADVECTION IN THE 500-300 MB LAYER
LATE SUNDAY NIGHT INTO MONDAY MORNING. THE GFS SHOWS STRONG
ISENTROPIC UP GLIDE SHOULD SPREAD ACROSS THE AREA SUNDAY NIGHT
AHEAD OF THE SHORT WAVE TROUGH WITH UP TO 10 UBAR/S ON THE 305K
SURFACE. THE NOSE OF THE LOW LEVEL JET IS EXPECTED TO BECOME
ORIENTED INTO THE AREA SUNDAY EVENING WITH LITTLE MOVEMENT SUNDAY
NIGHT BEFORE VEERING OFF TO THE EAST MONDAY MORNING. WITH THE
AMPLE FORCING...WIDESPREAD SHOWERS AND STORMS ARE EXPECTED TO MOVE
IN SUNDAY EVENING AND WORK EAST ACROSS THE AREA BEFORE ENDING
MONDAY AFTERNOON. GOOD CAPE WILL BUILD SUNDAY AFTERNOON WEST OF
THE AREA AHEAD OF THE COLD FRONT ASSOCIATED WITH THIS SYSTEM. THE
GFS SUGGESTS THAT AN AXIS OF 1000-1500 J/KG OF ML CAPE WILL
PERSIST AHEAD OF THE FRONT THROUGH THE NIGHT AS THE SYSTEM WORKS
ACROSS THE AREA. GOOD SHEAR LOOKS TO OVERSPREAD THE REGION WITH 40
TO 50 KNOTS OF 0-6KM SHEAR...BUT MOST OF THIS LOOKS TO BE IN THE
0-3KM LAYER WITH 35 TO 40 KNOTS. EXPECT THAT THIS WILL BE
SUFFICIENT TO SUPPORT SOME STRONG TO SEVERE STORMS WITH HAIL AND
WIND THE MAIN THREATS.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 321 AM CDT SAT AUG 30 2014
SOME SMALL RAIN CHANCES WILL CONTINUE INTO TUESDAY AS A SECONDARY
SHORT WAVE TROUGH LOOKS TO SWEEP ACROSS THE UPPER MIDWEST.
AGAIN...THERE SHOULD BE GOOD DRYING SO THE QUESTION BECOMES IF THE
FORCING WILL BE ENOUGH TO GENERATE SOME ACTIVITY. AFTER
THAT...RIDGING LOOKS TO BUILD OVER THE REGION FOR A SHORT PERIOD
WEDNESDAY AND WEDNESDAY NIGHT. THE FLOW THEN SHOULD BECOME
SOUTHWEST ALLOWING A POSITIVE TILT LONG WAVE TROUGH TO APPROACH
FROM THE NORTHWEST. DIFFERENCES BETWEEN THE ECMWF AND GFS ON HOW
FAST THIS TROUGH MOVES THROUGH WITH THE ECMWF CONSIDERABLY FASTER.
WILL HAVE SOME RAIN CHANCES WITH THIS SYSTEM BUT WILL UNDERCUT THE
MODEL CONSENSUS GRIDS SOME THINKING THE RIDGE WILL BE THE DOMINANT
FEATURE THROUGH THE END OF THE PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1240 PM CDT SAT AUG 30 2014
MAIN STORM CIRCULATION NOW WELL EAST OF THE AREA...BUT LOW CLOUDS
AND SHOWERS STILL WRAPPING AROUND THE CYCLONIC CIRCULATION.
VISIBLE SATELLITE IMAGERY SHOWS SOME BREAKS IN THE CLOUD AND
INDEED MODEL SOUNDINGS SHOW THE MOISTURE LAYER IS SOMEWHAT THIN.
STILL...WHERE CLEARING TAKES PLACE THE SKY QUICKLY SELF-DESTRUCTS
WITH NEW CUMULUS DEVELOPMENT. RADAR IMAGERY WAS SHOWING SOME LIGHT
SHOWERS DEVELOPING IN THESE AREAS AS WELL. SO ANTICIPATE AN
AFTERNOON AND EARLY EVENING OF MVFR TO VFR CEILINGS BETWEEN 25-35
KFT WITH OCCASIONAL LIGHT SHOWERS. TONIGHT...MODELS SUGGEST LOW
CLOUDS WILL DIMINISH AS SUBSIDENCE SETS IN. FEEL IT WILL PROBABLY
HAPPEN...BUT NOT AS QUICKLY AS MODELS INDICATE. STILL...OPTED TO
CLEAR OUT THE MVFR CEILING FOR A TIME TONIGHT. THE PROBLEM WITH
THAT...THERE IS STILL A LOT OF BOUNDARY LAYER MOISTURE
AROUND...AND AS WINDS GO LIGHT...EXPECT FOG TO FORM. PREVIOUS
FORECAST INCLUDED LIGHT FOG BUT OPTED IN ENHANCE THAT
FURTHER...ESPECIALLY AT KLSE. MIXING PICKS UP SUNDAY MORNING AHEAD
OF THE NEXT SYSTEM...SO THE FOG SHOULD QUICKLY ERODE BY 14-15Z.
&&
.HYDROLOGY...
ISSUED AT 321 AM CDT SAT AUG 30 2014
ADDITIONAL RAINFALL TODAY WILL BE A QUARTER INCH OR LESS AND THIS
WILL NOT BE ENOUGH TO CAUSE ANY FLOODING PROBLEMS. WITH THE SYSTEM
THAT WILL AFFECT THE AREA SUNDAY NIGHT AND MONDAY...CURRENT
EXPECTATIONS ARE THAT THE RAIN TOTALS WILL BE AN INCH OR LESS. THE
PRECIPITABLE WATER IS NOT EXPECTED TO BE QUITE AS HIGH WITH THE
GFS SHOWING AROUND 1.75 INCHES BUT WARM CLOUD DEPTHS WILL STILL BE
IN THE 3.5 TO 4 KM RANGE. THE SHOWERS AND STORMS WILL HAVE THE
POTENTIAL TO PRODUCE SOME HIGHER RAIN RATES...BUT WITH THE
CONVECTION EXPECTED TO BE PROGRESSIVE...IT SHOULD NOT POSE ANY
LARGE SCALE FLOODING PROBLEMS AND PLAN TO ISSUE THE LAST ESF THIS
MORNING STATING THIS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...MW
HYDROLOGY...04