Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/25/12
AREA FORECAST DISCUSSION
NWS DENVER CO
340 PM MDT THU AUG 23 2012
.SHORT TERM...A RATHER DISORGANIZED UPPER LEVEL TROUGH OVER
SOUTHERN UT AND NORTHERN AZ THIS AFTERNOON WILL SLOWLY MOVE EAST
ACROSS SOUTHERN COLORADO TONIGHT AND FRIDAY. THE AIRMASS WILL
REMAIN VERY MOIST BUT SO FAR THE SHOWERS AND TSTMS HAVE BEEN SLOW
TO DEVELOP THIS AFTERNOON. THE LATEST HRRR HOWEVER CONTINUES TO
DEVELOP PRECIPITATION OVER THE CWFA TONIGHT...WITH THE BEST
POTENTIAL TO THE WEST AND SOUTH OF DENVER. PRECIPITABLE WATER
VALUES WILL BE OVER ONE INCH WITH SLOW STORM MOTIONS SO A FEW
STORMS COULD PRODUCE BRIEF HEAVY RAINFALL...BUT EXTENSIVE CLOUD
COVER TODAY HAS LIMITED THEIR DEVELOPMENT SO FAR. WL KEEP THE POPS I
INHERITED FOR THE MOST PART...ONLY CHANGE WAS TO INCREASE THE POPS
TO CHC NEAR THE SRN FRONT RANGE FOOTHILLS AND PALMER DIVIDE. IN A
NUTSHELL...ALTHOUGH THE POTENTIAL FOR HEAVY RAIN EXISTS FOR THE
BURN AREAS...THE THREAT STILL TO BE MODERATE UNTIL MAYBE O2Z THEN LOW.
ON FRIDAY...VERY SIMILAR TO TODAY WITH A BIT MORE WARMING.
FORECAST SOUNDINGS FRIDAY AFTERNOON RANGE 200-300 J/KG AT KDEN TO
700-1100 J/KG AND KLIC AND KAKO RESPECTIVELY. THERE WILL BE SOME
WEAK QG ASCENT ASSOCIATED WITH THE TROUGH WHICH MAY HELP ENHANCE
THE PCPN BUT EXTENSIVE CLOUD COVER MAY AGAIN LIMIT THE STRENGTH/COVERAGE
OF THE TSTMS. BEST POPS WILL BE OVER THE SRN HALF OF THE CWFA
WITH DRYING DEVELOPING OVER THE NRN HALF OF THE CWFA ONCE THE
SYSTEM MAKES ITS WAY INTO SERN CO LATE IN THE DAY.
.LONG TERM...TROUGH TO BE CENTERED ACROSS EASTERN COLORADO FRIDAY
EVENING. SHOULD CONTINUE TO SEE DRIER AND MORE SUBSIDENT AIR
MOVING IN FROM THE NORTH. STILL SOME CHANCE FOR THUNDERSTORMS...MAINLY
ACROSS THE SOUTHERN SECTIONS OF THE CFWA IN THE AREA OF BEST MID
LEVEL QG ASCENT. PRECIPITABLE WATER VALUES ON THE DECREASE...BUT
STILL CLOSE TO AN INCH ALONG PALMER DIVIDE. MAY STILL SEE BRIEF
MODERATE TO HEAVY RAIN WITH THE STORMS THERE...WITH LIGHTER
AMOUNTS ELSEWHERE. COULD ALSO SEE SOME GUSTY OUTFLOW WINDS. TROUGH
TO SLOWLY MOVE INTO WESTERN KANSAS OVERNIGHT WITH MOST IF NOT ALL
OF THE ASCENT EAST OF THE AREA. FOR THIS REASON...WILL DROP MOST
OF THE POPS AND WEATHER AFTER MIDNIGHT KEEPING A SLIGHT CHANCE
OVER THE HIGHER MOUNTAINS. ON SATURDAY...TROUGH TO BE CENTERED
OVER CENTRAL AND WESTERN KANSAS AS UPPER RIDGE BUILDS ACROSS GREAT
BASIN. MODELS CONTINUE TO SHOW COLD FRONT MOVING THROUGH THE
PLAINS DURING THE EARLY MORNING HOURS. WINDS COULD GUST TO AROUND
20 KTS FOR A COUPLE HOURS FOLLOWING FRONT. COOLER AIR EXPECTED
FOLLOWING FRONT WITH HIGHS ONLY IN THE LOWER 80S ACROSS PLAINS.
THE COOLER AIR WILL ALSO HELP TO STABILIZE THE ATMOSPHERE.
MOUNTAINS NOT EXPECTED TO BE AFFECTED BY THE FRONT SOME
TEMPERATURES THERE TO BE SIMILAR TO FRIDAY`S READINGS. AIRMASS TO
BE SLIGHTLY UNSTABLE OVER THE HIGH COUNTRY BY THE AFTERNOON AND
WITH LINGERING MOISTURE...COULD SEE SOME HIGH BASED STORMS DEVELOP
ACROSS THE HIGHER TERRAIN DURING THE AFTERNOON CONTINUING INTO THE
EVENING. FOR SUNDAY...HIGH PRESSURE TO CONTINUE TO BUILD ACROSS
GREAT BASIN AS WELL AS WESTERN COLORADO. AS A RESULT...AIRMASS TO BE
MAINLY DRY AND WARMER WITH HIGHS INTO THE MID AND UPPER 80S ACROSS
PLAINS. STILL SOME MOISTURE NOTED ON CROSS SECTIONS ACROSS
MOUNTAINS FOR A SLIGHT CHANCE OF AFTERNOON AND EVENING HIGH BASED
STORMS. BOTH NAM AND GFS HINT AT A WEAK DISTURBANCE MOVING ACROSS
CENTRAL PLAINS DURING THE AFTERNOON. THERE IS SOME WEAK QG ASCENT
AS WELL. BOTH MODELS ALSO PAINT SOME LIGHT QPF ACROSS AREA
INCLUDING PLAINS. BUT AIRMASS ALSO FAIRLY DRY AS NOTED BY LOWER
PRECIPITABLE WATER VALUES. FOR NOW WILL NOT INTRODUCE POPS FOR
PLAINS BUT WILL ADD A BIT MORE CLOUD.
FOR THE MONDAY THROUGH THURSDAY PERIOD...MODELS SHOW UPPER RIDGE
ACROSS COLORADO THROUGH THE PERIOD...THOUGH ECMWF SHOW RIDGE OVER
CENTRAL PLAINS BY LATE WEDNESDAY WITH UPPER TROUGH ACROSS GREAT
BASIN. ECMWF LOOKS TO THE THE OUTLIER AT THIS POINT AND WILL
DISCOUNT. SO SHOULD SEE A MAINLY DRY AND WARM AIRMASS OVER THE
AREA THROUGH THE PERIOD. SOME MOISTURE WILL BE PRESENT FOR A
SLIGHT CHANCE OF THUNDERSTORMS OVER THE HIGH COUNTRY EACH
AFTERNOON AND EVENING. GUIDANCE INDICATING HIGHS COULD BE 90
DEGREES OR BETTER DURING THIS PERIOD...WHICH WILL LIKELY BREAK THE
STRING OF DAYS OF 90 DEGREES OR GREATER FOR DENVER...THE RECORD
BEING 61 DAYS. CURRENTLY DENVER ONLY 2 DAYS FROM TYING THE
RECORD...AND STRING COULD BE BROKEN WEDNESDAY IF GUIDANCE IS
CORRECT.
&&
.AVIATION...VFR CONDITIONS EXPECTED THROUGH THE PERIOD. SHOWERS
AND TSTMS DEVELOPING WEST AND SOUTH OF DENVER SHOULD DRIFT INTO
THE DENVER AREA THROUGH O0-02Z. IF TSTMS DEVELOP AT KDEN THEN CIGS
COULD DEVELOP IN THE 5-6 KFT AGL RANGE. WITH SFC LOW TO THE SOUTH
WINDS MAY CONTINUE TO FLUCTUATE FM NWLY TO NELY THROUGH THIS
EVENING. DEVELOPING SHOWERS AND TSTMS WILL ONLY CONFUSE THE ISSUE
FURTHER. SHOULD SEE WINDS TRANSITION TO SWLY LATE THIS EVENING
BUT DRAINAGE WINDS WILL BE SLOW TO DEVELOP WITH SHOWERS AND CLOUD
COVER LINGERING OVERNIGHT.
&&
.HYDROLOGY...THREAT OF THUNDERSTORMS WILL BE GREATEST PRIOR TO 02Z
WITH LINGERING LIGHT RAIN SHOWERS OVERNIGHT. A THUNDERSTORM THIS
AFTN OR EARLY THIS EVENING COULD PRODUCE A MODERATE TO HEAVY RAIN
SHOWER WITH A QUARTER OF ONE HALF INCH OF RAIN IN 30 MINUTES. IN
SPITE OF THE HIGH MOISTURE CONTENT EXTENSIVE CLOUD COVER HAS
LIMITED THE TSTMS DEVELOPMENT SO FAR THIS AFTN. THE THREAT OF HEAVY
RAIN WILL BE MODERATE IN THE BURN AREAS UNTIL 02Z THEN LOW
THEREAFTER.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...COOPER
LONG TERM....D-L
AVIATION...COOPER
AREA FORECAST DISCUSSION
NWS ALBANY NY
130 PM EDT THU AUG 23 2012
.SYNOPSIS...
HIGH PRESSURE WILL BE SITUATED JUST TO THE SOUTHWEST OF
THE REGION THIS AFTERNOON. THIS WILL ALLOW FOR A GOOD DEAL OF
SUNSHINE AND DRY WEATHER...ALONG WITH WARM TEMPERATURES. THIS HIGH
PRESSURE AREA WILL REMAIN OVER THE NORTHEAST INTO THE
WEEKEND...ALLOWING FOR MAINLY DRY WEATHER WITH CONTINUED WARM
TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 130 PM...HIGH CLOUDS HAVE MOVED OUT OF THE REGION. WE DO HAVE
SOME PRETTY GOOD CU BUILDUPS...MAINLY OVER THE HIGHER TERRAIN. MODEL
SOUNDINGS INDICATED ONLY MODEST INSTABILITY (MAYBE UP TO 500 J/KG)
ALONG WITH A WEAK MID LEVEL CAP DEVELOPING DURING THE AFTERNOON. THE
LATEST EXPERIMENTAL HRRR AND HIRESWRF INDICATE NOTHING MORE THAN
SOME POSSIBLE SPRINKLES OVER THE HIGHER TERRAIN (DZ VALUES LESS THAN
25). MOISTURE REMAINS SOMEWHAT LIMITED THROUGH THE COLUMN.
FOR THE AFTERNOON...THE ONLY CHANGE WAS TO ADD SOME CLOUDS ACROSS
THE HIGHER TERRAIN (AND CALL IT PARTLY SUNNY THERE).
OTHERWISE...LEFT THE HIGH TEMPERATURES ALONE AND ONLY MINOR
RE-TOOLING OF THE HOURLY GRIDS REQUIRED.
LOOK FOR HIGHS IN THE MID 80S ACROSS MOST VALLEY AREA...MID 70S TO
LOWER 80S ACROSS THE HIGHER TERRAIN. THE WIND WILL REMAIN VARIABLE
TO WEST GENERALLY UNDER 10 MPH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
THE HIGH PRESSURE AREA WILL REMAIN ANCHORED OVER THE REGION
THROUGH MUCH OF THE SHORT TERM PERIOD. SKIES WILL REMAIN FAIRLY
CLEAR TONIGHT...EXCEPT FOR SOME PATCHY FOG THAT MAY DEVELOP LATE
AT NIGHT IN SOME AREAS...ESP NEAR BODIES OF WATER. WITH THE
CONTINUED GOOD RADIATIONAL COOLING...IT WILL BE ANOTHER
COMFORTABLE NIGHT WITH LOWS RANGING FROM THE UPPER 40S TO THE
UPPER 50S.
CONTINUED SUNNY SKIES AND WARM TEMPERATURES ARE EXPECTED AGAIN FOR
FRIDAY. 850 HPA TEMPS MAY EVEN NUDGE A DEGREE OR TWO WARMER...SO
SOME UPPER 80S ARE POSSIBLE IN THE HUDSON VALLEY. DEWPOINTS WILL
START TO CREEP UP AS WELL...WITH SOME READINGS IN THE UPPER 50S TO
NEAR 60 F...SO IT WILL START TO FEEL A LITTLE MORE MUGGY THAN
RECENT DAYS...ALTHOUGH CERTAINLY NOT AS BAD AS IT COULD BE FOR
THIS TIME OF YEAR.
THE MOSTLY CLEAR SKIES WILL CONTINUE INTO FRIDAY NIGHT AS
WELL...WITH THE HIGH PRESSURE STILL OVER THE AREA. MIN TEMPS MAY
BE A LITTLE WARMER THAN RECENT NIGHTS...WITH MINS NEAR 60 FOR THE
CAPITAL REGION.
BY SATURDAY...THE HIGH WILL START TO SHIFT OFF THE COAST...AND A
MOIST SOUTHERLY FLOW WILL START TO KICK IN. SOME OF THE MODELS
HINT AT A VERY WEAK UPPER LEVEL DISTURBANCE OVER THE MID ATLANTIC
STATES. THIS NEARBY UPPER LOW...COMBINED WITH THE INCREASING
HUMIDITY...AND DAYTIME HEATING...MIGHT ALLOW FOR AN ISOLD TO
SCATTERED SHOWER OR THUNDERSTORM TO DEVELOP IN THE
AFTERNOON...MAINLY FOR THE HIGHER TERRAIN AREAS TO THE SOUTHWEST
OF THE CAPITAL REGION. DUE TO THE POSSIBLE PRECIP...AND PERHAPS A
FEW MORE CLOUDS AND THE MORE HUMID SOUTHERLY FLOW...MAX TEMPS ON
SATURDAY MAY BE A FEW DEGREES LESS THAN FRIDAY...WITH READINGS IN
THE MID 80S.
ANY SHOWER OR THUNDERSTORM THREAT SHOULD END WITH THE LOSS OF
HEATING FOR SATURDAY NIGHT...WITH A MOSTLY CLEAR TO PARTLY CLOUDY
SKY OVERNIGHT. MIN TEMPS WILL RANGE FROM THE MID 50S TO THE MID
60S...AND IT WILL REMAIN A LITTLE ON MUGGY SIDE.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
DRY WEATHER IS EXPECTED TO HOLD THROUGH SUNDAY. THE RIDGE OF HIGH
PRESSURE WILL FINALLY SLIDE EAST OF THE FA AND WEAKEN ON MONDAY AS A
COLD FRONT MOVES INTO THE CENTRAL AND EASTERN GREAT LAKES. THIS
FEATURE WILL RESULT IN A CHANCE OF SHOWERS AND A SLIGHT CHANCE OF
THUNDERSTORMS FROM MONDAY AFTERNOON INTO TUESDAY. A WAVE OF LOW
PRESSURE MAY DEVELOP AND MOVE NORTHEAST ALONG THE FRONT KEEPING
UNSETTLED WEATHER ACROSS THE FA INTO TUESDAY AFTERNOON. HIGH
PRESSURE IS THEN EXPECTED TO RETURN ON WEDNESDAY WITH DRIER
CONDITIONS.
ON SUNDAY...HIGH PRESSURE WILL REMAIN ANCHORED ACROSS THE NORTHEAST
STATES FOR ONE MORE DAY WITH SLIGHTLY ABOVE NORMAL TEMPS AS HIGHS
ARE EXPECTED TO BE IN THE UPPER 70S TO LOWER 80S WITH LOWS SUNDAY
NIGHT IN THE 50S TO LOWER 60S.
MONDAY AND TUESDAY...IT NOW APPEARS THAT UNSETTLED WEATHER WILL
RETURN BY MONDAY AFTERNOON AND LINGER INTO TUESDAY WITH COLD FRONT
MOVING FROM CENTRAL GREAT LAKES MONDAY MORNING INTO FA TUESDAY
MORNING AS A WAVE OF LOW PRESSURE TRACKS NORTHEAST ALONG THE FRONT
FROM THE OHIO VALLEY. SHOWALTER INDICES DROP TO AROUND ZERO FROM
MONDAY AFTERNOON INTO TUESDAY...SO SOME EMBEDDED THUNDERSTORMS
POSSIBLE AND WILL INCLUDE SLIGHT CHANCE OF THUNDERSTORMS ALONG WITH
CHANCE POPS AT THIS TIME. QPF AMOUNTS ARE HIGHLY UNCERTAIN AT THIS
TIME. HIGHS ARE EXPECTED TO BE IN THE UPPER 70S TO MID 80S ON MONDAY
AND 70S TO LOWER 80S ON TUESDAY WITH SOME UPPER 60S POSSIBLE ACROSS
THE WESTERN ADIRONDACKS. LOWS MONDAY NIGHT ARE EXPECTED TO BE IN THE
UPPER 50S TO MID 60S.
TUESDAY NIGHT AND WEDNESDAY...EXPECT A RETURN TO DRIER WEATHER AS
HIGH PRESSURE BUILDS EAST ACROSS THE GREAT LAKES INTO THE NORTHEAST
ON WEDNESDAY. EXPECT LOWS TUESDAY NIGHT IN THE UPPER 40S TO UPPER
50S WITH HIGHS ON WEDNESDAY IN THE UPPER 60S TO NEAR 80.
&&
.AVIATION /17Z THURSDAY THROUGH MONDAY/...
VFR CONDITIONS ARE EXPECTED AT THE TAF SITES FOR MUCH OF THE TAF
PERIOD ENDING AT 18Z FRIDAY AS HIGH PRESSURE WILL REMAIN ACROSS OUR
REGION. THERE COULD BE SOME FOG EARLY TOMORROW MORNING AT KGFL...
KPSF AND KPOU TONIGHT LIKE IN THE PAST FEW EARLY MORNINGS. ONCE FOG
BURNS OFF EARLY IN THE MORNING...EXPECT SKC TO SCT CLOUD CONDITIONS
DURING THE REMAINDER OF TOMORROW MORNING.
THE WINDS WILL BE FROM THE WEST OR SOUTHWEST AT LESS THAN 8 KTS FROM
THROUGH THIS AFTERNOON. WINDS WILL BE CALM OR LIGHT AND VARIABLE
TONIGHT AND TOMORROW MORNING.
OUTLOOK...
FRI-SUN...MAINLY VFR CONDITIONS. CHC FOR LATE NT/EARLY AM
BR/FOG ESPECIALLY AT KGFL AND KPSF.
MON...VFR...SLIGHT CHC/CHC SHRA/TSRA.
TUE...VFR/MVFR CHC SHRA/TSRA.
&&
.FIRE WEATHER...
HIGH PRESSURE WILL REMAIN CLOSE TO THE REGION THROUGH THE WEEKEND. IT
WILL REMAIN MAINLY DRY THROUGH THE WEEKEND...ALTHOUGH A STRAY
SHOWER OR THUNDERSTORM CANNOT BE RULED OUT ON SATURDAY.
RH VALUES WILL DROP TO 30-45 PERCENT THIS AFTERNOON...BUT WILL
RECOVER TO NEAR 100 PERCENT TONIGHT WITH DEW FORMATION. RH VALUES
WILL AGAIN DROP TO 35-50 PERCENT FOR SATURDAY AFTERNOON.
CALM WINDS THIS MORNING WILL PICK UP TO 5-10 MPH FROM THE W-SW FOR
THIS AFTERNOON. NEARLY CALM WINDS ARE EXPECTED AGAIN TONIGHT.
WINDS WILL REMAIN LIGHT AND VARIABLE FOR FRIDAY.
&&
.HYDROLOGY...
NO HYDRO PROBLEMS ARE EXPECTED FOR THE NEXT FIVE DAYS.
NO PRECIPITATION IS EXPECTED TODAY AND TOMORROW...WITH JUST AN
ISOLATED TO SCATTERED LIGHT RAIN SHOWER OR THUNDERSTORM ON
SATURDAY...MAINLY OVER THE HIGH TERRAIN OF THE CATSKILLS. IT
SHOULD STAY DRY FOR SUNDAY AND MONDAY. ANY SHOWER OR THUNDERSTORM
ON SATURDAY WOULD BE RATHER LIGHT...AND SHOULD HAVE LITTLE TO NO
EFFECT ON STREAM FLOW ACROSS THE REGION. RIVERS AND STREAMS WILL
REMAIN CLOSE TO CURRENT LEVELS OR SLOWLY RECEDE INTO EARLY NEXT
WEEK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...FRUGIS/NAS
NEAR TERM...HWJIV/NAS
SHORT TERM...FRUGIS
LONG TERM...11
AVIATION...NAS
FIRE WEATHER...FRUGIS
HYDROLOGY...FRUGIS
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
140 AM EDT THU AUG 23 2012
.SYNOPSIS...
WEAK LOW PRESSURE WILL MOVE UP THE COAST TONIGHT AND THURSDAY. HIGH
PRESSURE WILL THEN BUILD IN FROM THE NORTHEAST FRIDAY THROUGH THE
WEEKEND AND LINGER OVER THE EASTERN SEABOARD INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
WATER VAPOR IMAGERY AND RAP VORTICITY ANALYSIS SHOW A SECONDARY
SHORTWAVE MOVING INTO THE CSRA. THIS FEATURE IS FORECAST
TO CROSS THE AREA OVERNIGHT AS A WEAK WAVE OF LOW PRESSURE RIDES
NORTHEAST ALONG AN ILL-DEFINED STATIONARY FRONT THAT IS IN PLACE
ACROSS EASTERN SOUTH CAROLINA/GEORGIA. UVV ASSOCIATED WITH THE
SHORTWAVE IS ALREADY BEGINNING TO IMPINGE ACROSS THE MIDLANDS AND
CSRA WHERE A RECENT UPTICK IN SHOWER/TSTM ACTIVITY IS NOTED. BEST
CHANCES FOR MEASURABLE RAINFALL WILL BE FOUND AT THE COAST WHERE
THE COMBINATION OF ENHANCED UVV ALOFT AND LOW-LVL COASTAL
CONVERGENCE WILL SUPPORT SCATTERED SHOWERS/TSTMS. WILL MAINTAIN
20-30 PERCENT POPS AREA WIDE TONIGHT WITH THE HIGHEST GRIDDED POPS
REMAINING ACROSS THE COASTAL COUNTIES. WE HAVE INITIATED WITH A
BIT WARMER TEMPS EARLY THIS MORNING AND HAVE INCREASED LOW TEMPS A
BIT IN A FEW SPOTS GIVEN RECENT TRENDS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY/...
THURSDAY...THE UPPER TROUGH WILL BE STEADILY DAMPENING...WHILE
SUBTLE SURFACE WAVES TRACK ALONG THE WEAKENING STATIONARY FRONT
ALONG THE COASTLINE. BOTH THE 12Z GFS AND 12Z NAM ARE IN GOOD
AGREEMENT THAT SHOWERS/THUNDERSTORMS WILL INCREASE IN COVERAGE
THROUGH THE LATE MORNING AND EARLY AFTERNOON HOURS. CONVECTION
WILL BE ENHANCED BY ELONGATED SHORTWAVE ENERGY MOVING INTO THE
REGION DOWNSTREAM OF THE UPPER TROUGH AXIS TO THE WEST...AS WELL
AS LINGERING MOISTURE AND CONVERGENCE ALONG THE DISSIPATING
FRONT/DEVELOPING COASTAL TROUGH. HAVE THUS BUMPED UP RAIN CHANCES
A BIT FOR THURSDAY TO INDICATE SCATTERED THUNDERSTORMS DURING THE
PEAK HEATING/INSTABILITY PERIOD OF THE LATE AFTERNOON/EARLY
EVENING HOURS. PERSISTENT CLOUD COVER...NORTH/NORTHEAST LOW LEVEL
FLOW...AND LOWER HEIGHTS WITHIN THE WEAK UPPER TROUGH...WILL
SUPPRESS HIGH TEMPERATURES IN THE LOW TO MID 80S...SEVERAL DEGREES
BELOW SEASONAL NORMALS. EXPECT PRECIPITATION POTENTIAL TO DECREASE
OVERNIGHT AS THE SHORTWAVE AND ASSOCIATED DEEPEST MOISTURE PULLS
OFFSHORE.
FRIDAY AND SATURDAY...SURFACE HIGH PRESSURE WILL STEADILY BUILD
FROM THE NORTH/NORTHWEST...AS THE UPPER LEVEL PATTERN BECOMES
INCREASINGLY DIFFUSE. THERE IS SOME EVIDENCE THAT A SUBTLE AND
BROAD AREA OF LOW PRESSURE ALOFT WILL SET UP OVER THE MID ATLANTIC
STATES...AS WELL AS WEAK SHORTWAVE ENERGY EMBEDDED WITHIN.
HOWEVER...UPPER LEVEL SUPPORT WILL BE QUITE LACKING FOR THE
REMAINDER OF THE SHORT TERM PERIOD. CONVECTION FRIDAY AND
SATURDAY WILL THUS MAINLY BE DRIVEN BY TYPICAL DAYTIME
HEATING/INSTABILITY...SEABREEZE CONVERGENCE...AND ANY INFLUENCES
FROM A WEAK COASTAL TROUGH. HAVE THEREFORE INDICATED A MORE
TYPICAL SUMMERTIME CONVECTIVE SCHEME...WITH 20 TO 30 PERCENT POPS
ALONG AND INLAND OF THE SEABREEZE EACH AFTERNOON/EARLY EVENING.
PARTLY CLOUDY SKIES WILL GENERALLY PREVAIL...AND EXPECT HIGH
TEMPERATURES TO BE ON A WARMING TREND THROUGH SATURDAY...WHILE
STILL REMAINING A FEW DEGREES BELOW SEASONAL NORMALS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
FORECAST CONFIDENCE IN THE LONG TERM PERIOD IS QUITE LOW AND ALMOST
SOLELY DEPENDS ON THE EVENTUAL TRACK AND INTENSITY OF TROPICAL
STORM ISAAC. PREFER TO REMAIN RATHER GENERIC AT THIS TIME...FAVORING
A SOLUTION SIMILAR TO EARLIER GFS MODEL RUNS...WITH CHANCE POPS
BEGINNING MONDAY AND CONTINUING THROUGH MID WEEK. POTENTIAL
IMPACTS AND FORECAST DETAILS WILL COME MORE INTO FOCUS AS FORECAST
CONFIDENCE INCREASES. CONTINUE TO STAY TUNED TO NATIONAL HURRICANE
CENTER ADVISORIES ON TROPICAL STORM ISAAC FOR THE LATEST FORECAST
TRACK AND INTENSITY INFORMATION.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
OVERNIGHT THERE IS A RISK FOR PERIODS OF MVFR CIGS WHICH WILL BE
ON THE DIFFICULT SIDE TO PIN DOWN. TOWARD DAYBREAK...MODEL FORECAST
SOUNDINGS SUGGEST IFR CIGS AT KSAV ONCE AGAIN AND WE HAVE OPTED FOR
SOME LOWER CIGS AROUND DAYBREAK THERE.
MVFR CIGS SEEM FAIRLY LIKELY INTO LATE MORNING TODAY THEN VFR THIS
AFTERNOON AND EVENING. ISOLATED TO SCATTERED SHOWERS AND A FEW
TSTMS EXPECTED TO DEVELOP MID TO LATE AFTERNOON WITH THE SEA
BREEZE SLUGGISH TO MOVE INLAND.
EXTENDED AVIATION OUTLOOK...SCATTERED SHOWERS/TSTMS COULD IMPACT
THE TERMINALS AT ANYTIME DURING THE NEXT SEVERAL DAYS BRINGING A
RISK FOR SUB-VFR CONDITIONS.
&&
.MARINE...
A DIMINISHING STATIONARY FRONT WILL LINGER IN THE VICINITY OF THE
LOCAL WATERS ON THURSDAY BEFORE DISSIPATING BY FRIDAY. HIGH
PRESSURE WILL THEN BUILD IN FROM THE NORTH AND PERSIST THROUGH THE
WEEKEND. A RELATIVELY LIGHT AND ERRATIC FLOW CAN BE EXPECTED OVER
THE WATERS EARLY IN THE PERIOD...BEFORE A MORE SOLID NORTHEAST TO
ENE FLOW SETS UP ALONG THE PERIPHERY OF THE BUILDING HIGH PRESSURE
DURING THE WEEKEND. OVERALL...CONDITIONS ARE EXPECTED TO BE
RELATIVELY BENIGN AND REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA
THROUGH THE WEEKEND.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...79
LONG TERM...BSH
AVIATION...JRL
MARINE...
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
636 PM CDT FRI AUG 24 2012
.DISCUSSION...
324 PM CDT
TODAY THROUGH SATURDAY NIGHT...
AN UPPER LEVEL DISTURBANCE IS SLOWLY PASSING THROUGH NORTHERN
WISCONSIN AND WILL CONTINUE EASTWARD THROUGH THE NORTHERN GREAT
LAKES THIS EVENING. SOME OF THE SHORT TERM MODELS INDICATE
SCATTERED SHOWERS WILL DEVELOP ACROSS NORTHERN ILLINOIS...BUT WILL
CONTINUE WITH A DRY FORECAST THIS AFTERNOON. LATEST RAP ANALYSIS
INDICATES AMPLE CAPE AND LOW LEVEL LAPSE RATES NEAR DRY
ADIABATIC...HOWEVER SUSPECTING THE RAP ANALYSIS MAY BE OVER
ESTIMATING CAPE VALUES. ALSO TOOK INTO CONSIDERATION THAT THE UPPER
LEVEL WAVE IS WELL NORTH OF THE CWA...AND CONVECTION/SHOWERS OVER
LAKE MICHIGAN ARE ASSOCIATED WITH AN AREA OF 850 HPA WARM AIR
ADVECTION. SCT CU IS BEGINNING TO DEVELOP ROUGHLY ALONG THE I-55
CORRIDOR.
SKIES CLEAR TONIGHT AND EXPECTING A COMFORTABLE NIGHT DESPITE LOW
90S BEING REPORTED ACROSS THE CWA THIS AFTERNOON. OVERNIGHT LOWS
WILL BE IN THE MID 60S...EXCEPT FOR LOW 70S DOWNTOWN. SATURDAY WILL
BE MUCH LIKE TODAY...WITH A DRY AND HOT FORECAST. RAISED INHERITED
TEMPS SUCH THAT TOMORROWS HIGHS ARE A DEGREE OR TWO WARMER THAN
TODAY. COULD EVEN SEE AREAS IN THE SOUTHERN PORTIONS OF THE CWA
BEING A BIT WARMER THAN CURRENTLY FORECAST. MODEL SOUNDINGS
INDICATES THERE WILL BE PLENTY OF MIXING TOMORROW...THEREFORE WENT
WITH DEW POINTS SLIGHTLY LOWER THAN PREVIOUSLY FORECAST. MIN RH
VALUES WILL BE IN THE MID TO UPPER 20 PERCENT RANGE...BUT WITH LIGHT
WINDS FORECAST NOT ANTICIPATING ANY FIRE WEATHER HEADLINES. THAT
BEING SAID A FEW LOCATIONS MAY REACH RED FLAG CRITERIA...AS RFD DID
TODAY. KEPT PREVIOUS MIN TEMPS FOR SATURDAY NIGHT WITH MID TO UPPER
60S IN THE OUTLYING AREAS...AND IN THE LOW 70S DOWNTOWN.
SUNDAY THROUGH MONDAY NIGHT...
LOW PRESSURE CURRENTLY OVER SOUTHERN SASKATCHEWAN AND THE NORTHERN
GREAT PLAINS WILL MOVE EASTWARD ACROSS SOUTHERN CANADA THROUGH THE
WEEKEND. THE LOWS COLD FRONT PASSES THROUGH THE CWA LATE SUNDAY
NIGHT INTO MONDAY MORNING. PRECIP AHEAD OF THE COLD FRONT WAS THE
MAIN FORECAST CHALLENGE TODAY. THE NAM AND GFS LOOKED A BIT FAST
WHILE THE ECMWF HAS BEEN SLOWING THE PROGRESSION OF THE SHOWERS
AND THUNDERSTORMS THE PAST FEW RUNS. WENT WITH A NAM/ECMWF MIX
THAT WAS VERY SIMILAR TO THE PREVIOUS FORECASTS TIMING...WITH
PRECIP REACHING THE WESTERN EDGE OF THE CWA LATE SATURDAY NIGHT.
THAT BEING SAID...THE MODELS ARE INDICATING THE INITIAL UPPER
LEVEL VORTICITY STREAMER ASSOCIATED WITH FIRST WAVE OF PRECIP WILL
BE STRETCHED NORTH TO SOUTH AND FRACTURE SOMEWHERE OVER WISCONSIN.
THE SOUTHERN PART OF THE VORT STREAMER WILL THEN PROGRESS EASTWARD
BRINGING MUCH NEEDED RAIN TO NORTHERN ILLINOIS. CONFIDENCE IS
MEDIUM WITH THE TIMING AND PROGRESSION OF THE PRECIP...BUT HIGH
REGARDING THE POSSIBILITY OF IT BEING A SIGNIFICANT RAINFALL.
PW VALUES WILL BE AROUND TO SLIGHTLY ABOVE 2 INCHES AHEAD OF THE
FRONT...WHICH IS AROUND 2 STANDARD DEVIATIONS ABOVE NORMAL FOR
AUGUST. THEREFORE SUBSTANTIAL RAINFALL IS POSSIBLE AND AS MENTIONED
IN THE PREVIOUS DISCUSSION...TRAINING CELLS COULD CAUSE ISOLATED
WATER PROBLEMS.
TEMPS ON SUNDAY WILL BE MUCH COOLER WITH AREAS WEST OF I-55 IN THE
UPPER 70S...AND LOW TO MID 80S EXPECTED EAST OF I-55. TEMPS REBOUND
SLIGHTLY ON MONDAY WITH HIGHS IN THE LOW TO MID 80S.
EXTENDED...TUESDAY THROUGH FRIDAY...
HIGH PRESSURE MOVES IN BEHIND THE COLD FRONT LEADING TO ANOTHER
EXTENDED PERIOD OF DRY WEATHER. TEMPS INCREASE THROUGHOUT THE
EXTENDED...AND COULD BE EVEN WARMER THAN FORECAST. EXPECTING UPPER
80S TO QUITE POSSIBLY 90S BY LATE NEXT WEEK.
JEE
&&
.FIRE WEATHER...
428 PM CDT
RH VALUES DROPPED INTO THE 20 PERCENT RANGE ACROSS PARTS OF THE
AREA TODAY...AND SIMILAR CONDITIONS ARE EXPECTED TOMORROW.
TEMPERATURES TOMORROW WILL ONCE AGAIN BE IN THE LOW TO MID
90S...WITH LOWER DEW POINTS THAN TODAY. AMPLE MIXING WILL LIKELY
LEAD TO DEW POINTS DROPPING INTO THE LOW 50S SATURDAY AFTERNOON.
MIN RH VALUES WILL BE IN THE LOW TO MID 20 PERCENT RANGE...HOWEVER
WIND SPEEDS WILL BE AROUND 10 MPH. WIND GUSTS WILL DEVELOP IN THE
AFTERNOON WITH GUSTS UP TO 20 MPH EXPECTED WEST OF I-39...AND
GUSTS AROUND 15 MPH EXPECTED EAST OF I-39. FUEL MOISTURE LEVELS
ARE ABOVE 10 PERCENT FOR MUCH OF NORTHERN ILLINOIS...WHILE AREAS
EAST OF I-55 HAVE 10-HOUR FUELS LESS THAN 10 PERCENT. THEREFORE
TWO OF THE THREE RED FLAG CONDITIONS MAY BE MET IN ISOLATED
LOCATIONS...SIMILAR TO TODAY...BUT NOT EXPECTING ALL THREE RED
FLAG CONDITIONS TO BE MET. THEREFORE NO FIRE WEATHER HEADLINES ARE
ANTICIPATED.
A COLD FRONT MOVES THROUGH THE REGION LATE SATURDAY NIGHT INTO
SUNDAY BRINGING A WIDESPREAD SOAKING RAIN AND COOLER TEMPERATURES
WITH IT.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* SS-SSE WINDS AROUND 10 KT OCCASIONALLY GUSTING TO AROUND 15 KT
THROUGH DUSK.
* VERY SLIGHT POTENTIAL LAKE BREEZE REACHING MDW AND/OR ORD
BEFORE SUNDOWN.
* VERY LOW PROB ISOLATED SHRA/TSRA OVER NE IL AND EXTREME SE WI
INTO THIS EVENING.
TRS
//DISCUSSION...UPDATED 00Z...
LAKE BREEZE ONLY MAKING VERY SLOW PROGRESS INLAND. 09-14 KT
SE-ESE WINDS RIGHT ALONG THE SHORE BUT FURTHER INLAND BEHIND
THE BOUNDARY THERE ARE SSE-SE 05-07KT. EXTRAPOLATION USING
RECENT MOVEMENT HAS ARRIVAL AT ORD NOT TIL 02Z. WINDS LATE
AFTERNOON INTO TONIGHT EXPECTED TO REMAIN OUT OF THE S-SSE.
FAIRLY WEAK CONVERGENCE ALONG LAKE BREEZE AND OTHER BOUNDARIES
BUT HAS BEEN ENOUGH TO GENERATE ISOLATED SHRA WITH ADDITIONAL
LIFT PROVIDED BY THE SHORT WAVE TROUGH CURRENTLY MOVING E ALONG
THE WESTERN IL-WI BORDER. EXPECT A FEW MORE ISOLATED SHOWERS
INTO EARLY EVENING THEN DISSIPATION OF THE HIGH BASED CU WITH
LOSS OF SURFACE HEATING WITH SUNSET.
WITH SUNSET THE SURFACE WILL START TO DECOUPLE FROM THE 13-18KT
S-SSW LOW LEVEL FLOW AND WILL FALL OF TO A VERY LIGHT BREEZE AT
MOST FOR THE NIGHT. SAT TO BE SIMILAR TO TODAY. WINDS PICK BACK
UP AFTER A COUPLE HOURS OF HEATING AND SCT HIGH BASED CU POP WHEN
CONVECTIVE TEMPERATURE OF ABOUT 87F REACHED AROUND 16Z. VERY LOW
PROB OF ANY SHRA/TSRA DURING THE DAY AS A SHORT WAVE WILL BE
MOVING NORTHEASTWARD FROM EASTERN NE AND KS REACHING IA BY 00Z
SUN KEEPING ANY SIGNIFICANT CHANCES OF PRECIP W OF THE MS RIVER
THROUGH THE DAY. ONLY LOCAL AFFECT WILL BE AN INCREASING LAYER OF
CI OVERSPREADING THE AREA DURING THE LATER AFTERNOON. AS THE
SHORT WAVE AND ITS ASSOCIATED SURFACE TROUGH MOVE TO NE IA AND SW
WI BY SUNRISE ON SUN THERE WILL BE BETTER CHANCES OF SHRA/TSRA IN
NW AND FAR N CENTRAL IL OVERNIGHT SAT.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* HIGH CONFIDENCE ALL ELEMENTS...INCLUDING NO MORE THAN ISOLATED
SHRA EARLY THIS EVE AND NEAR ZERO CHANCE OF OCCURRENCE AT OR
WITHIN IMMEDIATE VICINITY OF TERMINALS.
TRS
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...CHANCE TSRA DURING A.M. THEN LIKELY DURING P.M.
PREVAILING VFR BUT LOCAL MVFR OR IFR WITH ANY TS.
MONDAY...SLIGHT CHANCE TSRA DURING A.M. OTHERWISE VFR THROUGH
THE DAY.
TUESDAY TROUGH THURSDAY...VFR. WX NIL.
TRS
&&
.MARINE...
219 PM CDT
PATTERN REMAINS LARGELY UNCHANGED TODAY AND WILL CONTINUE TO PERSIST
THROUGH MUCH OF THE WEEKEND AS HIGH PRESSURE REMAINS ANCHORED OVER
THE EASTERN STATES AND LOW PRESSURE PERSISTS OVER THE CANADIAN
PRAIRIES. SOUTHERLY FLOW WILL CONTINUE ACROSS LAKE MICHIGAN UNTIL
LATE SUNDAY. THROUGH SUNDAY NIGHT...THE LOW PRESSURE IS FORECAST TO
DEEPEN AS IT LIFTS NORTHEAST TOWARDS HUDSON BAY...AND A TRAILING
COLD FRONT IS EXPECTED TO MOVE ACROSS LAKE MICHIGAN LATE SUNDAY
NIGHT INTO MONDAY TURNING WINDS TO THE WEST OR NORTHWEST. HIGH
PRESSURE WILL THEN BUILD ACROSS THE PLAINS STATES AND MOVE
EAST...BECOMING CENTERED JUST SOUTH OF THE GREAT LAKES REGION. THE
WINDS WILL BE LIGHT OVER THE SOUTHERN HALF OF THE LAKE CLOSE TO THE
HIGH CENTER...BUT THE NORTH HALF OF THE LAKE WILL SEE SLIGHTLY
WINDIER CONDITIONS AS ANOTHER AREA OF LOW PRESSURE DEVELOPS ACROSS
THE CANADIAN PRAIRIES AND A MODEST PRESSURE GRADIENT DEVELOPS OVER
NORTHERN LAKE MICHIGAN. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
253 PM CDT THU AUG 23 2012
.DISCUSSION...
917 AM CDT
MADE SOME MINOR EDITS TO THE SKY COVER/WEATHER GRIDS THROUGH THE
AFTERNOON...TO ACCOUNT FOR PERSISTENT PARTLY CLOUDY/PARTLY SUNNY
SKIES AND POSSIBLE SCATTERED SPRINKLES.
LATEST SATELLITE IMAGERY SHOWING AREA OF MID LEVEL CLOUD COVER
ACROSS NORTHERN ILLINOIS SLOWLY SHIFTING EAST...BUT WITH CLOUD
COVER CONTINUING TO DEVELOP ACROSS THE WESTERN FRINGE OF THIS
CLOUD SHIELD. LATEST RUC ANALYSIS INDICATING WAA CONTINUING ACROSS
NORTHERN ILLINOIS...WITH THE SHOWERS OBSERVED THIS MORNING PARTLY
DUE TO THIS WEAK ASCENT. AS A MID LEVEL WAVE SHIFTS TO THE EAST
ACROSS THE MIDWEST...WAA SHOULD CONTINUE INTO THE AFTERNOON WITH
EVEN SOME OF THE SHORT RANGE GUIDANCE INDICATING THIS POSSIBILITY.
THE LATEST HRRR IS SHOWING SOME SCATTERED SHOWER DEVELOPMENT FOR
THE REMAINDER OF THE DAY MAINLY FOR AREAS ALONG AND NORTH OF LINE
FROM PONTIAC TO CHICAGO. WITH THIS WEAK ASCENT EXPECTED IN THIS
GENERAL AREA AS WELL AS LATEST VISIBLE IMAGERY ALREADY SHOWING A
CUMILIFORM NATURE TO THE CLOUD DEVELOPMENT ACROSS EASTERN IOWA AND
WESTERN ILLINOIS...FELT IT WAS AT LEAST POSSIBLE FOR SCATTERED
SPRINKLES AND HAVE INCLUDED THIS POSSIBILITY IN THE FORECAST
THROUGH THIS AFTERNOON. DESPITE WEAK INSTABILITY IN
PLACE...FORCING SHALL BE WEAK ENOUGH FOR THUNDER TO BE
NONEXISTENT TODAY.
RODRIGUEZ
//PREV DISCUSSION...
303 AM CDT
THE WARMING TREND WILL CONTINUE INTO THE WEEKEND AND OVERALL
CONDITIONS LOOK TO BE DRY FOR THE NEXT SEVERAL DAYS...BUT THERE ARE
SEVERAL SUBTLETIES THAT COULD POINT TO SOME SPOTTY PRECIP
DEVELOPMENT BEFORE A WELL ORGANIZED SYSTEM ARRIVES SOMETIME SUNDAY.
MORNING MOISTURE CHANNEL IMAGERY SHOWS A LONGWAVE UPPER TROUGH AXIS
NOW PUSHING OFF THE EASTERN SEABOARD. MORE OF A ZONAL WEST TO EAST
FLOW IS SITUATED ACROSS THE NORTHERN CORRIDOR OF THE U.S. BUT THERE
ARE SEVERAL WEAK TROUGHS AND RIDGES EMBEDDED WITHIN THIS FLOW. THE
MORE NOTABLE FEATURES INCLUDE AN UPPER LOW LIFTING NORTHEASTWARD
ACROSS SASKATCHEWAN WITH AN ASSOCIATED TROUGH AXIS EXTENDING INTO
THE CENTRAL DAKOTAS...WHICH HAS FORCED WEAK RIDGING OUT AHEAD OF IT
WHICH DAMPENS OUT JUST TO THE WEST OF THE LOCAL AREA. A LARGE CLOSED
UPPER LOW IS NOW SPINNING OVER THE BRITISH COLUMBIA COAST WHILE A
CUTOFF LOW IS SLOWLY WORKING TOWARD THE FOUR CORNERS REGION. THESE
TWO SYSTEMS WILL BE THE PRIMARY FOCUS FOR PRECIP CHANCES LATER IN
THE WEEKEND. AT THE SURFACE...THE HIGH PRESSURE WHICH HAS DOMINATED
OUR LOCAL WEATHER THE PAST FEW DAYS HAS SHIFTED EASTWARD ACROSS THE
MID ATLANTIC REGION. ELONGATED LOW PRESSURE STRETCHES FROM CENTRAL
SASKATCHEWAN INTO WESTERN MINNESOTA AND INTO THE CENTRAL PLAINS IN
RESPONSE TO THE LOW AMPLITUDE TROUGH AXIS MENTIONED ABOVE.
TODAY THROUGH SATURDAY...THE DAMPENED UPPER RIDGING WILL CROSS THE
AREA THIS MORNING WITH MID LEVEL WARM ADVECTION ALREADY UNDERWAY. A
WEAK TROUGH FOLLOWS THE RIDGE INTO EARLY AFTERNOON BUT IS SLIGHTLY
MORE AMPLIFIED TO THE NORTH. IN ADDITION TO SOME INCREASED MID AND
HIGH CLOUD COVER SOME SCATTERED SPRINKLES ARE MOVING ACROSS THE AREA
AT THE CURRENT TIME BUT THESE WILL PROBABLY END BY MID MORNING.
CLOUD COVER APPEARS TO THIN THIS AFTERNOON...ESPECIALLY
WEST...ALLOWING FOR A DECENT AMOUNT OF SUNSHINE. WITH THE HIGH
MOVING OFF TO THE EAST THE PRESSURE GRADIENT WILL BE STRONGER THAN
PREVIOUS DAYS SUPPORTING A SOUTHERLY BREEZE. BETWEEN THE INCREASING
SUNSHINE...WARMER MID LEVELS...AND A SOUTH WIND...HIGHS WILL BE
WARMER THAN WEDNESDAY WITH READINGS IN THE UPPER 80S TO AROUND
90...WITH THE WARMEST READINGS WEST. FRIDAY...THE TROUGH WORKING
ACROSS SASKATCHEWAN/CENTRAL DAKOTAS THIS MORNING WILL MOVE ACROSS
THE AREA MIDDAY FRIDAY. THIS TROUGH WILL BE PRETTY STRETCHED OUT AND
LIFTING NORTHEASTWARD SO FORCING WILL BE PRETTY WEAK THIS FAR SOUTH.
AT THIS POINT SEE LITTLE SUPPORT FOR ORGANIZED SHOWER ACTIVITY SO
WILL GO WITH A DRY FORECAST. FRIDAY HIGHS SHOULD BE SLIGHTLY
WARMER THAN TODAY WITH MOST IF NOT ALL AREAS REACHING 90. SATURDAY
SHOULD BE A DRY DAY WITH HIGHS RIGHT AROUND THOSE OBSERVED FRIDAY.
SUNDAY THROUGH WEDNESDAY...THE CLOSED UPPER LOW CURRENTLY OVER THE
BRITISH COLUMBIA COAST WILL BE MOVING ACROSS CENTRAL/SOUTHERN
MANITOBA SATURDAY NIGHT. THE MAIN QUESTION IS HOW MUCH THE UPPER LOW
CURRENTLY APPROACHING THE FOUR CORNERS PHASES WITH THIS NORTHERN
STREAM SYSTEM. THE GFS AND ECMWF CONTINUE TO HAVE DIFFERENCES IN
THE MAGNITUDE OF PHASING AND ARE THEREFORE DIFFERENT WITH RESPECT
TO WHEN THIS SYSTEM CROSSES THE AREA. THE ECMWF IS LESS PHASED AND
THEREFORE KEEPS THE SOUTHERN STREAM TROUGH STRONGER WITH A BETTER
ORGANIZED SURFACE LOW ACCOMPANYING IT AS IT MOVES ACROSS THE MID
MISSISSIPPI RIVER VALLEY SUNDAY. THE GFS IS FASTER AND HAS THE
UPPER TROUGH PHASED TO A GREATER DEGREE. STILL PREFER THE ECMWF
OVERALL THOUGH IT IS JUST A BIT FASTER THAN EARLIER RUNS. THE 00Z
RUN WHICH HAS JUST ARRIVED IS SLIGHTLY MORE PHASED THAN THE 12Z
RUN BUT THE TIMING OF THE SYSTEM IS ABOUT THE SAME. THIS RESULTS
IN RAIN/THUNDER CHANCES SPREADING FROM WEST TO EAST SUNDAY AND
EXITING SOMETIME MONDAY. THE UPPER FLOW PATTERN WILL AMPLIFY AS
THIS SYSTEM MOVES EASTWARD WITH A LARGE RIDGE BUILDING TO THE
WEST. THIS WILL LEAVE THE AREA UNDER A NORTHWESTERLY UPPER FLOW
WHICH WILL ALLOW COOLER AIR TO SPREAD IN FROM THE NORTH MONDAY
NIGHT. FROM THAT POINT ON OUR WEATHER WILL BE DRIVEN BY HOW
PROGRESSIVE THE UPPER FLOW PATTERN BECOMES THROUGH THE REST OF
NEXT WEEK ALONG WITH INTERACTION BETWEEN IT AND TROPICAL SYSTEM
ISAAC WHICH WILL LIKELY BE ENTERING THE GULF OF MEXICO BY EARLY
NEXT WEEK.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* WINDS GUSTING INTO MID TEENS THIS AFTERNOON AND AGAIN FRIDAY
AFTERNOON.
* PRECIP CHANCES OVERNIGHT. BMD
//DISCUSSION...UPDATED 18Z...
OVERALL PATTERN REMAINS LARGELY UNCHANGED AND IS EXPECTED TO PERSIST
OVER THE NEXT 24 HRS OR SO. CONTINUE TO EXPECT SSW TO SSE WINDS
AROUND 10 KT. WINDS MAY GUST INTO THE MID TEENS THIS
AFTERNOON...WITH BETTER CHANCES TOMORROW AFTERNOON AS THE GRADIENT
TIGHTENS SLIGHTLY. ONLY OTHER CONCERN IN THE FORECAST IS PRECIP
CHANCES OVERNIGHT. NAM/GFS GUIDANCE IN PARTICULAR INDICATE A WEAK
UPPER LEVEL DISTURBANCE TRAVELING JUST NORTH OF THE AREA WITH WEAK
ISENTROPIC ASCENT HELPING TO DEVELOP A FEW SHOWERS. SOUNDINGS
CONTINUE TO LOOK DRY AND MAY BE AN INHIBITING FACTOR...BUT GIVEN THE
SHOWER ACTIVITY THAT HAPPENED THIS MORNING...ATMOSPHERE SEEMS
CAPABLE OF SUPPORTING AT LEAST SOME SHOWERS REACHING THE SURFACE
WITH MVFR CIGS IN THE HEAVIER SHOWERS. FOR NOW...DO NOT HAVE ENOUGH
CONFIDENCE IN SHOWERS IMPACTING TERMINALS SO WILL NOT MENTION IN
TAF. BMD
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN WIND GUST SPEEDS THIS AFTERNOON...MEDIUM TO
HIGH CONFIDENCE FOR FRIDAY AFTERNOON.
* MEDIUM CONFIDENCE WIDELY SCATTERED SHOWERS DEVELOPING LATE
TONIGHT/EARLY FRIDAY. LOW CONFIDENCE IN SHOWERS IMPACTING
TERMINALS.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. BMD
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...VFR. WX NIL.
SATURDAY...VFR. WX NIL.
SUNDAY...CHANCE TSRA. OTHERWISE...VFR.
MONDAY...CHANCE TSRA EARLY. OTHERWISE...VFR.
TUESDAY...VFR. WX NIL.
WEDNESDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
229 PM CDT
A TROUGH OF LOW PRESSURE STRETCHING FROM SASKATCHEWAN TO THE
SOUTHERN HIGH PLAINS WILL REMAIN NEARLY STATIONARY THROUGH FRIDAY
NIGHT...WHILE A DEEP AREA OF LOW PRESSURE DEVELOPS WITHIN THE
NORTHERN PERIPHERY OF THIS TROUGH OVER SASKATCHEWAN. THIS LOW WILL
MOVE NORTHEAST ACROSS MANITOBA SATURDAY AND SATURDAY NIGHT...AND
OVER HUDSON BAY SUNDAY AND SUNDAY NIGHT. THIS WILL SET UP A
PROLONGED PERIOD OF SOUTH WINDS ACROSS LAKE MICHIGAN THROUGH THE
WEEKEND. WARM AIR SPREADING ACROSS THE LAKE ON THESE SOUTH WINDS
WILL TEND TO LIMIT THE DEPTH OF THE MIXED LAYER OVER THE WATER...
WITH MODEL FORECAST SOUNDINGS DEPICTING 15-20 KTS AND SOME GUSTS
INTO THE 20-25 KT RANGE PARTICULARLY OVER THE NORTHERN AND NORTH
CENTRAL PARTS OF THE LAKE. SOME GUIDANCE DEPICTS A WEAKER SURFACE
WAVE DEVELOPING ACROSS THE MIDWEST BY EARLY SUNDAY...ALONG THE COLD
FRONT TRAILING THE DEEPER CANADIAN LOW. SOUTH-SOUTHEAST WINDS MAY
BRIEFLY PICK UP NEAR 20 KTS ON THE SOUTHERN PORTION OF THE LAKE
AHEAD OF THIS WAVE EARLY SUNDAY. THE COLD FRONT WILL THEN TRANSLATE
EAST ACROSS LAKE MICHIGAN SUNDAY NIGHT...WITH THE GRADIENT WEAKENING
IN THE VICINITY OF THE FRONTAL TROUGH WITH WINDS SHIFTING TO THE
NORTH-NORTHWEST. WEAK HIGH PRESSURE WILL THEN SPREAD ACROSS THE
UPPER MIDWEST BEHIND THE FRONT SUNDAY NIGHT AND MONDAY...MOVING
ACROSS THE WESTERN AND NORTHERN LAKES MONDAY NIGHT AND TUESDAY.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
230 PM CDT THU AUG 23 2012
.DISCUSSION...
917 AM CDT
MADE SOME MINOR EDITS TO THE SKY COVER/WEATHER GRIDS THROUGH THE
AFTERNOON...TO ACCOUNT FOR PERSISTENT PARTLY CLOUDY/PARTLY SUNNY
SKIES AND POSSIBLE SCATTERED SPRINKLES.
LATEST SATELLITE IMAGERY SHOWING AREA OF MID LEVEL CLOUD COVER
ACROSS NORTHERN ILLINOIS SLOWLY SHIFTING EAST...BUT WITH CLOUD
COVER CONTINUING TO DEVELOP ACROSS THE WESTERN FRINGE OF THIS
CLOUD SHIELD. LATEST RUC ANALYSIS INDICATING WAA CONTINUING ACROSS
NORTHERN ILLINOIS...WITH THE SHOWERS OBSERVED THIS MORNING PARTLY
DUE TO THIS WEAK ASCENT. AS A MID LEVEL WAVE SHIFTS TO THE EAST
ACROSS THE MIDWEST...WAA SHOULD CONTINUE INTO THE AFTERNOON WITH
EVEN SOME OF THE SHORT RANGE GUIDANCE INDICATING THIS POSSIBILITY.
THE LATEST HRRR IS SHOWING SOME SCATTERED SHOWER DEVELOPMENT FOR
THE REMAINDER OF THE DAY MAINLY FOR AREAS ALONG AND NORTH OF LINE
FROM PONTIAC TO CHICAGO. WITH THIS WEAK ASCENT EXPECTED IN THIS
GENERAL AREA AS WELL AS LATEST VISIBLE IMAGERY ALREADY SHOWING A
CUMILIFORM NATURE TO THE CLOUD DEVELOPMENT ACROSS EASTERN IOWA AND
WESTERN ILLINOIS...FELT IT WAS AT LEAST POSSIBLE FOR SCATTERED
SPRINKLES AND HAVE INCLUDED THIS POSSIBILITY IN THE FORECAST
THROUGH THIS AFTERNOON. DESPITE WEAK INSTABILITY IN
PLACE...FORCING SHALL BE WEAK ENOUGH FOR THUNDER TO BE
NONEXISTENT TODAY.
RODRIGUEZ
//PREV DISCUSSION...
303 AM CDT
THE WARMING TREND WILL CONTINUE INTO THE WEEKEND AND OVERALL
CONDITIONS LOOK TO BE DRY FOR THE NEXT SEVERAL DAYS...BUT THERE ARE
SEVERAL SUBTLETIES THAT COULD POINT TO SOME SPOTTY PRECIP
DEVELOPMENT BEFORE A WELL ORGANIZED SYSTEM ARRIVES SOMETIME SUNDAY.
MORNING MOISTURE CHANNEL IMAGERY SHOWS A LONGWAVE UPPER TROUGH AXIS
NOW PUSHING OFF THE EASTERN SEABOARD. MORE OF A ZONAL WEST TO EAST
FLOW IS SITUATED ACROSS THE NORTHERN CORRIDOR OF THE U.S. BUT THERE
ARE SEVERAL WEAK TROUGHS AND RIDGES EMBEDDED WITHIN THIS FLOW. THE
MORE NOTABLE FEATURES INCLUDE AN UPPER LOW LIFTING NORTHEASTWARD
ACROSS SASKATCHEWAN WITH AN ASSOCIATED TROUGH AXIS EXTENDING INTO
THE CENTRAL DAKOTAS...WHICH HAS FORCED WEAK RIDGING OUT AHEAD OF IT
WHICH DAMPENS OUT JUST TO THE WEST OF THE LOCAL AREA. A LARGE CLOSED
UPPER LOW IS NOW SPINNING OVER THE BRITISH COLUMBIA COAST WHILE A
CUTOFF LOW IS SLOWLY WORKING TOWARD THE FOUR CORNERS REGION. THESE
TWO SYSTEMS WILL BE THE PRIMARY FOCUS FOR PRECIP CHANCES LATER IN
THE WEEKEND. AT THE SURFACE...THE HIGH PRESSURE WHICH HAS DOMINATED
OUR LOCAL WEATHER THE PAST FEW DAYS HAS SHIFTED EASTWARD ACROSS THE
MID ATLANTIC REGION. ELONGATED LOW PRESSURE STRETCHES FROM CENTRAL
SASKATCHEWAN INTO WESTERN MINNESOTA AND INTO THE CENTRAL PLAINS IN
RESPONSE TO THE LOW AMPLITUDE TROUGH AXIS MENTIONED ABOVE.
TODAY THROUGH SATURDAY...THE DAMPENED UPPER RIDGING WILL CROSS THE
AREA THIS MORNING WITH MID LEVEL WARM ADVECTION ALREADY UNDERWAY. A
WEAK TROUGH FOLLOWS THE RIDGE INTO EARLY AFTERNOON BUT IS SLIGHTLY
MORE AMPLIFIED TO THE NORTH. IN ADDITION TO SOME INCREASED MID AND
HIGH CLOUD COVER SOME SCATTERED SPRINKLES ARE MOVING ACROSS THE AREA
AT THE CURRENT TIME BUT THESE WILL PROBABLY END BY MID MORNING.
CLOUD COVER APPEARS TO THIN THIS AFTERNOON...ESPECIALLY
WEST...ALLOWING FOR A DECENT AMOUNT OF SUNSHINE. WITH THE HIGH
MOVING OFF TO THE EAST THE PRESSURE GRADIENT WILL BE STRONGER THAN
PREVIOUS DAYS SUPPORTING A SOUTHERLY BREEZE. BETWEEN THE INCREASING
SUNSHINE...WARMER MID LEVELS...AND A SOUTH WIND...HIGHS WILL BE
WARMER THAN WEDNESDAY WITH READINGS IN THE UPPER 80S TO AROUND
90...WITH THE WARMEST READINGS WEST. FRIDAY...THE TROUGH WORKING
ACROSS SASKATCHEWAN/CENTRAL DAKOTAS THIS MORNING WILL MOVE ACROSS
THE AREA MIDDAY FRIDAY. THIS TROUGH WILL BE PRETTY STRETCHED OUT AND
LIFTING NORTHEASTWARD SO FORCING WILL BE PRETTY WEAK THIS FAR SOUTH.
AT THIS POINT SEE LITTLE SUPPORT FOR ORGANIZED SHOWER ACTIVITY SO
WILL GO WITH A DRY FORECAST. FRIDAY HIGHS SHOULD BE SLIGHTLY
WARMER THAN TODAY WITH MOST IF NOT ALL AREAS REACHING 90. SATURDAY
SHOULD BE A DRY DAY WITH HIGHS RIGHT AROUND THOSE OBSERVED FRIDAY.
SUNDAY THROUGH WEDNESDAY...THE CLOSED UPPER LOW CURRENTLY OVER THE
BRITISH COLUMBIA COAST WILL BE MOVING ACROSS CENTRAL/SOUTHERN
MANITOBA SATURDAY NIGHT. THE MAIN QUESTION IS HOW MUCH THE UPPER LOW
CURRENTLY APPROACHING THE FOUR CORNERS PHASES WITH THIS NORTHERN
STREAM SYSTEM. THE GFS AND ECMWF CONTINUE TO HAVE DIFFERENCES IN
THE MAGNITUDE OF PHASING AND ARE THEREFORE DIFFERENT WITH RESPECT
TO WHEN THIS SYSTEM CROSSES THE AREA. THE ECMWF IS LESS PHASED AND
THEREFORE KEEPS THE SOUTHERN STREAM TROUGH STRONGER WITH A BETTER
ORGANIZED SURFACE LOW ACCOMPANYING IT AS IT MOVES ACROSS THE MID
MISSISSIPPI RIVER VALLEY SUNDAY. THE GFS IS FASTER AND HAS THE
UPPER TROUGH PHASED TO A GREATER DEGREE. STILL PREFER THE ECMWF
OVERALL THOUGH IT IS JUST A BIT FASTER THAN EARLIER RUNS. THE 00Z
RUN WHICH HAS JUST ARRIVED IS SLIGHTLY MORE PHASED THAN THE 12Z
RUN BUT THE TIMING OF THE SYSTEM IS ABOUT THE SAME. THIS RESULTS
IN RAIN/THUNDER CHANCES SPREADING FROM WEST TO EAST SUNDAY AND
EXITING SOMETIME MONDAY. THE UPPER FLOW PATTERN WILL AMPLIFY AS
THIS SYSTEM MOVES EASTWARD WITH A LARGE RIDGE BUILDING TO THE
WEST. THIS WILL LEAVE THE AREA UNDER A NORTHWESTERLY UPPER FLOW
WHICH WILL ALLOW COOLER AIR TO SPREAD IN FROM THE NORTH MONDAY
NIGHT. FROM THAT POINT ON OUR WEATHER WILL BE DRIVEN BY HOW
PROGRESSIVE THE UPPER FLOW PATTERN BECOMES THROUGH THE REST OF
NEXT WEEK ALONG WITH INTERACTION BETWEEN IT AND TROPICAL SYSTEM
ISAAC WHICH WILL LIKELY BE ENTERING THE GULF OF MEXICO BY EARLY
NEXT WEEK.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* WINDS GUSTING INTO MID TEENS THIS AFTERNOON AND AGAIN FRIDAY
AFTERNOON.
* PRECIP CHANCES OVERNIGHT. BMD
//DISCUSSION...UPDATED 18Z...
OVERALL PATTERN REMAINS LARGELY UNCHANGED AND IS EXPECTED TO PERSIST
OVER THE NEXT 24 HRS OR SO. CONTINUE TO EXPECT SSW TO SSE WINDS
AROUND 10 KT. WINDS MAY GUST INTO THE MID TEENS THIS
AFTERNOON...WITH BETTER CHANCES TOMORROW AFTERNOON AS THE GRADIENT
TIGHTENS SLIGHTLY. ONLY OTHER CONCERN IN THE FORECAST IS PRECIP
CHANCES OVERNIGHT. NAM/GFS GUIDANCE IN PARTICULAR INDICATE A WEAK
UPPER LEVEL DISTURBANCE TRAVELING JUST NORTH OF THE AREA WITH WEAK
ISENTROPIC ASCENT HELPING TO DEVELOP A FEW SHOWERS. SOUNDINGS
CONTINUE TO LOOK DRY AND MAY BE AN INHIBITING FACTOR...BUT GIVEN THE
SHOWER ACTIVITY THAT HAPPENED THIS MORNING...ATMOSPHERE SEEMS
CAPABLE OF SUPPORTING AT LEAST SOME SHOWERS REACHING THE SURFACE
WITH MVFR CIGS IN THE HEAVIER SHOWERS. FOR NOW...DO NOT HAVE ENOUGH
CONFIDENCE IN SHOWERS IMPACTING TERMINALS SO WILL NOT MENTION IN
TAF. BMD
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE IN WIND GUST SPEEDS THIS AFTERNOON...MEDIUM TO
HIGH CONFIDENCE FOR FRIDAY AFTERNOON.
* MEDIUM CONFIDENCE WIDELY SCATTERED SHOWERS DEVELOPING LATE
TONIGHT/EARLY FRIDAY. LOW CONFIDENCE IN SHOWERS IMPACTING
TERMINALS.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. BMD
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...VFR. WX NIL.
SATURDAY...VFR. WX NIL.
SUNDAY...CHANCE TSRA. OTHERWISE...VFR.
MONDAY...CHANCE TSRA EARLY. OTHERWISE...VFR.
TUESDAY...VFR. WX NIL.
WEDNESDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
229 PM CDT
A TROUGH OF LOW PRESSURE STRETCHING FROM SASKATCHEWAN TO THE
SOUTHERN HIGH PLAINS WILL REMAIN NEARLY STATIONARY THROUGH FRIDAY
NIGHT...WHILE A DEEP AREA OF LOW PRESSURE DEVELOPS WITHIN THE
NORTHERN PERIPHERY OF THIS TROUGH OVER SASKATCHEWAN. THIS LOW WILL
MOVE NORTHEAST ACROSS MANITOBA SATURDAY AND SATURDAY NIGHT...AND
OVER HUDSON BAY SUNDAY AND SUNDAY NIGHT. THIS WILL SET UP A
PROLONGED PERIOD OF SOUTH WINDS ACROSS LAKE MICHIGAN THROUGH THE
WEEKEND. WARM AIR SPREADING ACROSS THE LAKE ON THESE SOUTH WINDS
WILL TEND TO LIMIT THE DEPTH OF THE MIXED LAYER OVER THE WATER...
WITH MODEL FORECAST SOUNDINGS DEPICTING 15-20 KTS AND SOME GUSTS
INTO THE 20-25 KT RANGE PARTICULARLY OVER THE NORTHERN AND NORTH
CENTRAL PARTS OF THE LAKE. SOME GUIDANCE DEPICTS A WEAKER SURFACE
WAVE DEVELOPING ACROSS THE MIDWEST BY EARLY SUNDAY...ALONG THE COLD
FRONT TRAILING THE DEEPER CANADIAN LOW. SOUTH-SOUTHEAST WINDS MAY
BRIEFLY PICK UP NEAR 20 KTS ON THE SOUTHERN PORTION OF THE LAKE
AHEAD OF THIS WAVE EARLY SUNDAY. THE COLD FRONT WILL THEN TRANSLATE
EAST ACROSS LAKE MICHIGAN SUNDAY NIGHT...WITH THE GRADIENT WEAKENING
IN THE VICINITY OF THE FRONTAL TROUGH WITH WINDS SHIFTING TO THE
NORTH-NORTHWEST. WEAK HIGH PRESSURE WILL THEN SPREAD ACROSS THE
UPPER MIDWEST BEHIND THE FRONT SUNDAY NIGHT AND MONDAY...MOVING
ACROSS THE WESTERN AND NORTHERN LAKES MONDAY NIGHT AND TUESDAY.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1225 PM CDT THU AUG 23 2012
.DISCUSSION...
ISSUED 1027 AM CDT THU AUG 23 2012
MOSTLY SUNNY SKIES PREVAIL ACROSS CENTRAL ILLINOIS THIS MORNING.
WARM FRONTAL BOUNDARY HAS LIFTED INTO NORTHERN ILLINOIS...WHERE
MID-LEVEL CLOUD COVER AND A FEW LIGHT SHOWERS ARE OCCURRING IN THE
CHICAGO AREA. FURTHER SOUTHWEST...SCT MID-LEVEL CLOUDS CONTINUE TO
DEVELOP IN A ZONE OF WARM ADVECTION ACROSS THE ILLINOIS RIVER
VALLEY. HIGH-RES MODELS SUCH AS THE HRRR AND 4KM WRF-NMM SUGGEST
SCT SHOWERS WILL DEVELOP IN THIS AREA DURING THE AFTERNOON. BASED
ON THE 12Z KILX UPPER AIR SOUNDING SHOWING VERY DRY AIR BELOW
10000FT...THINK CHANCES OF ANY PRECIP REACHING THE GROUND ARE SLIM
TO NONE. WILL THEREFORE CONTINUE WITH A DRY FORECAST TODAY.
INCREASED CLOUD COVER WEST OF I-55...BUT CONTINUED WITH SUNNY
SKIES FURTHER EAST AND SOUTH. TEMPS SEEM TO BE RIGHT ON
TARGET...WITH AFTERNOON HIGHS REACHING THE LOWER 90S ACROSS THE
BOARD. ONLY MINOR CHANGES MADE TO GRIDS...SO ZONE UPDATE IS NOT
NEEDED AT THIS TIME.
BARNES
&&
.AVIATION...
ISSUED 1223 PM CDT THU AUG 23 2012
VFR WILL PREVAIL AT ALL TERMINALS THROUGH THE VALID TAF PERIOD.
CURRENT VISIBLE SATELLITE SHOWING MOSTLY CLEAR SKIES...WITH ONLY A
FEW MID AND HIGH CLOUDS MAINLY IN THE NORTH. THIS SHOULD BE THE CASE
THROUGH MOST OF THE PERIOD. WINDS WILL BE GENERALLY SOUTHERLY AOB 10
KTS TODAY...AND THEN BACK A BIT MORE TO THE SOUTHEAST OVERNIGHT.
ECT/BARNES
&&
.PREV DISCUSSION...
ISSUED 306 AM CDT THU AUG 23 2012
FORECAST NOT MUCH OF A SHIFT FROM YESTERDAY. WEAK FLOW ALOFT OVER
THE MIDWEST WITH THE MAJORITY OF THE UPPER WAVE ACTIVITY NORTH OF
THE REGION. WITH THE LACK OF SIGNIFICANT FLOW...THE WARM AIR FROM
THE WESTERN HALF OF THE CONUS IS LEAKING INTO THE MIDWEST AT
MIDLEVELS OF THE ATMOSPHERE BRINGING ANOTHER BRIEF ROUND OF HOT
WEATHER FOR THE FORECAST THROUGH THE END OF THE WEEK. NEXT SYSTEM
ON APPROACH FOR THE LATTER HALF OF THE WEEKEND STILL A BIT OF A
CONUNDRUM FOR THE MODELS...WITH GFS A GENERAL MESS WITH AN OPEN
AND DIFFUSE WAVE STIRRING UP WAY TOO MUCH QPF... AND THE ECMWF
OVER DEVELOPING THE SURFACE SYSTEM WITH DYNAMICS UPSTAIRS A LITTLE
LACKING. FORECAST RESULTS VERY SIMILAR TO YESTERDAY.
SHORT TERM...TODAY AND TOMORROW...
HOT AND HOT...TEMPS AT 850 MB IN THE 19-20C RANGE BRINGING HIGH
TEMPS INTO THE 90S. MID AND HIGH LEVEL CLOUDS EXPECTED TO MOVE OUT...PLENTY
OF SUNSHINE IN PLACE FOR THE MAJORITY OF THE DAY AND A RATHER DRY
AIR COLUMN. SAME STORY FOR TOMORROW EXPECTED. DRY AND HOT. WILL
HAVE TO KEEP AN EYE ON RH VALUES FOR FIRE WEATHER CONCERNS. FOR
NOW...ABOVE RED FLAG CRITERIA AND RATHER WEAK WINDS...BUT THE
HEIGHTENED CONCERN FOR OUTDOOR BURNING CONTINUES IN THE WIDESPREAD
DROUGHT.
LONG TERM...SATURDAY THROUGH THURSDAY...
ALMOST THE SAME EXACT STORY AS YESTERDAY. SATURDAY IS ANOTHER HOT
DAY... POTENTIALLY TEMPERED A BIT BY APPROACHING CLOUD COVER LATE
IN THE DAY. GFS A BIT TOO WET WITH NEXT SYSTEM FOR THE SECOND HALF
OF THE WEEKEND...THE ECMWF A LITTLE TOO WOUND UP...AND TRACKING
THE OPEN WAVE ALOFT IS ALL OVER THE PLACE. GFS LOSING ITS SFC LOW
REPRESENTATION A BIT AND INSTEAD LOOKING FOR A MORE WIDESPREAD
ASCENT ALONG A SFC TROF...WHICH MAKES A BIT MORE SENSE IN THE
WEAK DYNAMICS. ECMWF IS A LITTLE SLOWER AND MORE SOUTHERLY WITH THE
BEGINNING OF THE DEVELOPMENT OF THE SYSTEM...NOT STRINGING OUT THE
ENERGY ALOFT...NOR ALONG A PRODUCTIVE SFC TROF...AND KEEPING THE SYSTEM
A BIT MORE COMPACT. ECMWF THEN OVERDOES IT A BIT INTO THE
MIDWEST...OVERDEEPENING THE SFC LOW SUN NIGHT WITH WEAK FLOW AND A
POS TILT TO THE WAVE IN THE FIRST PLACE. OPERATIONAL MODELS STILL
SHAKING OUT THE ACTUAL TRACK OF A WEAK SFC LOW WITH VERY LITTLE
FLOW ALOFT THIS FAR SOUTH. NAM/WRF FINALLY JOINING IN THE PARTY
FOR THE FORECAST AND COMING IN ON THE SIDE OF THE ECMWF FOR A
SLOWER START...AND IF ANYTHING...TRACKING THE SFC LOW A BIT TO THE
NORTH AND WEST ALONG THE MORE ACTIVE WAVE TRAIN. BEST CHANCES FOR
PRECIP WHERE THE SOLUTIONS CROSS...SUN NIGHT AND MONDAY.
HJS
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1125 AM CDT THU AUG 23 2012
.DISCUSSION...
917 AM CDT
MADE SOME MINOR EDITS TO THE SKY COVER/WEATHER GRIDS THROUGH THE
AFTERNOON...TO ACCOUNT FOR PERSISTENT PARTLY CLOUDY/PARTLY SUNNY
SKIES AND POSSIBLE SCATTERED SPRINKLES.
LATEST SATELLITE IMAGERY SHOWING AREA OF MID LEVEL CLOUD COVER
ACROSS NORTHERN ILLINOIS SLOWLY SHIFTING EAST...BUT WITH CLOUD
COVER CONTINUING TO DEVELOP ACROSS THE WESTERN FRINGE OF THIS
CLOUD SHIELD. LATEST RUC ANALYSIS INDICATING WAA CONTINUING ACROSS
NORTHERN ILLINOIS...WITH THE SHOWERS OBSERVED THIS MORNING PARTLY
DUE TO THIS WEAK ASCENT. AS A MID LEVEL WAVE SHIFTS TO THE EAST
ACROSS THE MIDWEST...WAA SHOULD CONTINUE INTO THE AFTERNOON WITH
EVEN SOME OF THE SHORT RANGE GUIDANCE INDICATING THIS POSSIBILITY.
THE LATEST HRRR IS SHOWING SOME SCATTERED SHOWER DEVELOPMENT FOR
THE REMAINDER OF THE DAY MAINLY FOR AREAS ALONG AND NORTH OF LINE
FROM PONTIAC TO CHICAGO. WITH THIS WEAK ASCENT EXPECTED IN THIS
GENERAL AREA AS WELL AS LATEST VISIBLE IMAGERY ALREADY SHOWING A
CUMILIFORM NATURE TO THE CLOUD DEVELOPMENT ACROSS EASTERN IOWA AND
WESTERN ILLINOIS...FELT IT WAS AT LEAST POSSIBLE FOR SCATTERED
SPRINKLES AND HAVE INCLUDED THIS POSSIBILITY IN THE FORECAST
THROUGH THIS AFTERNOON. DESPITE WEAK INSTABILITY IN
PLACE...FORCING SHALL BE WEAK ENOUGH FOR THUNDER TO BE
NONEXISTENT TODAY.
RODRIGUEZ
//PREV DISCUSSION...
303 AM CDT
THE WARMING TREND WILL CONTINUE INTO THE WEEKEND AND OVERALL
CONDITIONS LOOK TO BE DRY FOR THE NEXT SEVERAL DAYS...BUT THERE ARE
SEVERAL SUBTLETIES THAT COULD POINT TO SOME SPOTTY PRECIP
DEVELOPMENT BEFORE A WELL ORGANIZED SYSTEM ARRIVES SOMETIME SUNDAY.
MORNING MOISTURE CHANNEL IMAGERY SHOWS A LONGWAVE UPPER TROUGH AXIS
NOW PUSHING OFF THE EASTERN SEABOARD. MORE OF A ZONAL WEST TO EAST
FLOW IS SITUATED ACROSS THE NORTHERN CORRIDOR OF THE U.S. BUT THERE
ARE SEVERAL WEAK TROUGHS AND RIDGES EMBEDDED WITHIN THIS FLOW. THE
MORE NOTABLE FEATURES INCLUDE AN UPPER LOW LIFTING NORTHEASTWARD
ACROSS SASKATCHEWAN WITH AN ASSOCIATED TROUGH AXIS EXTENDING INTO
THE CENTRAL DAKOTAS...WHICH HAS FORCED WEAK RIDGING OUT AHEAD OF IT
WHICH DAMPENS OUT JUST TO THE WEST OF THE LOCAL AREA. A LARGE CLOSED
UPPER LOW IS NOW SPINNING OVER THE BRITISH COLUMBIA COAST WHILE A
CUTOFF LOW IS SLOWLY WORKING TOWARD THE FOUR CORNERS REGION. THESE
TWO SYSTEMS WILL BE THE PRIMARY FOCUS FOR PRECIP CHANCES LATER IN
THE WEEKEND. AT THE SURFACE...THE HIGH PRESSURE WHICH HAS DOMINATED
OUR LOCAL WEATHER THE PAST FEW DAYS HAS SHIFTED EASTWARD ACROSS THE
MID ATLANTIC REGION. ELONGATED LOW PRESSURE STRETCHES FROM CENTRAL
SASKATCHEWAN INTO WESTERN MINNESOTA AND INTO THE CENTRAL PLAINS IN
RESPONSE TO THE LOW AMPLITUDE TROUGH AXIS MENTIONED ABOVE.
TODAY THROUGH SATURDAY...THE DAMPENED UPPER RIDGING WILL CROSS THE
AREA THIS MORNING WITH MID LEVEL WARM ADVECTION ALREADY UNDERWAY. A
WEAK TROUGH FOLLOWS THE RIDGE INTO EARLY AFTERNOON BUT IS SLIGHTLY
MORE AMPLIFIED TO THE NORTH. IN ADDITION TO SOME INCREASED MID AND
HIGH CLOUD COVER SOME SCATTERED SPRINKLES ARE MOVING ACROSS THE AREA
AT THE CURRENT TIME BUT THESE WILL PROBABLY END BY MID MORNING.
CLOUD COVER APPEARS TO THIN THIS AFTERNOON...ESPECIALLY
WEST...ALLOWING FOR A DECENT AMOUNT OF SUNSHINE. WITH THE HIGH
MOVING OFF TO THE EAST THE PRESSURE GRADIENT WILL BE STRONGER THAN
PREVIOUS DAYS SUPPORTING A SOUTHERLY BREEZE. BETWEEN THE INCREASING
SUNSHINE...WARMER MID LEVELS...AND A SOUTH WIND...HIGHS WILL BE
WARMER THAN WEDNESDAY WITH READINGS IN THE UPPER 80S TO AROUND
90...WITH THE WARMEST READINGS WEST. FRIDAY...THE TROUGH WORKING
ACROSS SASKATCHEWAN/CENTRAL DAKOTAS THIS MORNING WILL MOVE ACROSS
THE AREA MIDDAY FRIDAY. THIS TROUGH WILL BE PRETTY STRETCHED OUT AND
LIFTING NORTHEASTWARD SO FORCING WILL BE PRETTY WEAK THIS FAR SOUTH.
AT THIS POINT SEE LITTLE SUPPORT FOR ORGANIZED SHOWER ACTIVITY SO
WILL GO WITH A DRY FORECAST. FRIDAY HIGHS SHOULD BE SLIGHTLY
WARMER THAN TODAY WITH MOST IF NOT ALL AREAS REACHING 90. SATURDAY
SHOULD BE A DRY DAY WITH HIGHS RIGHT AROUND THOSE OBSERVED FRIDAY.
SUNDAY THROUGH WEDNESDAY...THE CLOSED UPPER LOW CURRENTLY OVER THE
BRITISH COLUMBIA COAST WILL BE MOVING ACROSS CENTRAL/SOUTHERN
MANITOBA SATURDAY NIGHT. THE MAIN QUESTION IS HOW MUCH THE UPPER LOW
CURRENTLY APPROACHING THE FOUR CORNERS PHASES WITH THIS NORTHERN
STREAM SYSTEM. THE GFS AND ECMWF CONTINUE TO HAVE DIFFERENCES IN
THE MAGNITUDE OF PHASING AND ARE THEREFORE DIFFERENT WITH RESPECT
TO WHEN THIS SYSTEM CROSSES THE AREA. THE ECMWF IS LESS PHASED AND
THEREFORE KEEPS THE SOUTHERN STREAM TROUGH STRONGER WITH A BETTER
ORGANIZED SURFACE LOW ACCOMPANYING IT AS IT MOVES ACROSS THE MID
MISSISSIPPI RIVER VALLEY SUNDAY. THE GFS IS FASTER AND HAS THE
UPPER TROUGH PHASED TO A GREATER DEGREE. STILL PREFER THE ECMWF
OVERALL THOUGH IT IS JUST A BIT FASTER THAN EARLIER RUNS. THE 00Z
RUN WHICH HAS JUST ARRIVED IS SLIGHTLY MORE PHASED THAN THE 12Z
RUN BUT THE TIMING OF THE SYSTEM IS ABOUT THE SAME. THIS RESULTS
IN RAIN/THUNDER CHANCES SPREADING FROM WEST TO EAST SUNDAY AND
EXITING SOMETIME MONDAY. THE UPPER FLOW PATTERN WILL AMPLIFY AS
THIS SYSTEM MOVES EASTWARD WITH A LARGE RIDGE BUILDING TO THE
WEST. THIS WILL LEAVE THE AREA UNDER A NORTHWESTERLY UPPER FLOW
WHICH WILL ALLOW COOLER AIR TO SPREAD IN FROM THE NORTH MONDAY
NIGHT. FROM THAT POINT ON OUR WEATHER WILL BE DRIVEN BY HOW
PROGRESSIVE THE UPPER FLOW PATTERN BECOMES THROUGH THE REST OF
NEXT WEEK ALONG WITH INTERACTION BETWEEN IT AND TROPICAL SYSTEM
ISAAC WHICH WILL LIKELY BE ENTERING THE GULF OF MEXICO BY EARLY
NEXT WEEK.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* INCREASING SOUTHERLY WINDS BECMG 10KT GUSTING TO 15KT THIS
AFTERNOON. BMD
//DISCUSSION...UPDATED 12Z...
MAIN ISSUE THIS MORNING IS SOME SCATTERED SHOWERS FALLING FROM A
MID LEVEL CLOUD DECK. CLOUD BASES ACROSS THE REGION ARE BETWEEN
10KFT AND 15KFT...SO ANY PCPN HITTING THE GROUND SHOULD BE LIGHT.
LATEST RADAR IMAGERY SHOWS SOME HEAVIER SHOWERS TO THE NORTH OF
ORD/DPA. THESE SHOWERS HAVE A SOUTHEASTERLY TRACK...AND THERE IS
THE CHANCE THAT ORD COULD BE IMPACTED...BUT ANY PCPN WOULD BE VERY
BRIEF. OTHERWISE...EXPECTING THAT THE MID CLOUD DECK SHOULD BEGIN
TO MOVE OUT THIS AFTERNOON...LEAVE NO SIG CLOUD COVER. THE ONLY
OTHER CONCERN TODAY WILL BE WINDS. WINDS HAVE BEEN LIGHT AND
SOUTHERLY THROUGH THE NIGHT...BUT SHOULD BE INCREASING THROUGH THE
MORNING...BUT MAINTAINING A SOUTHERLY DIRECTION. EXPECT SPEEDS OF
10KT WITH OCNL GUSTS TO 15KT THIS AFTERNOON.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS. BMD
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...VFR. WX NIL.
SATURDAY...VFR. WX NIL.
SUNDAY...CHANCE TSRA. OTHERWISE...VFR.
MONDAY...CHANCE TSRA EARLY. OTHERWISE...VFR.
TUESDAY...VFR. WX NIL.
WEDNESDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
250 AM CDT
HIGH PRESSURE EXTENDING FROM NEW ENGLAND SOUTHWESTWARD TO THE
TEXAS GULF COAST WILL REMAIN NEARLY STATIONARY THROUGH
SUNDAY...WHILE A WEAK TROUGH OF LOW PRESSURE EXTENDS FROM
MANITOBA THROUGH THE CENTRAL PLAINS. THIS WILL KEEP SOUTHERLY
WINDS OF AROUND 15-20KT...OCCASIONALLY TO AROUND 25 KT...OVER THE
LAKE. A STRENGTHENING LOW PRESSURE SYSTEM WILL DROP OUT OF THE
CANADIAN ROCKIES AND MOVE OUT OVER SOUTHERN MANITOBA SATURDAY.
THIS LOW WILL TRACK NORTHEAST TO HUDSON BAY BY SUNDAY NIGHT WHILE
DRAGGING A COLD FRONT ACROSS THE WESTERN GREAT LAKES
REGION...TURNING WINDS OVER LAKE MICHIGAN TO WESTERLY OR
NORTHWESTERLY BY SUNDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1027 AM CDT THU AUG 23 2012
.DISCUSSION...
ISSUED 1027 AM CDT THU AUG 23 2012
MOSTLY SUNNY SKIES PREVAIL ACROSS CENTRAL ILLINOIS THIS MORNING.
WARM FRONTAL BOUNDARY HAS LIFTED INTO NORTHERN ILLINOIS...WHERE
MID-LEVEL CLOUD COVER AND A FEW LIGHT SHOWERS ARE OCCURRING IN THE
CHICAGO AREA. FURTHER SOUTHWEST...SCT MID-LEVEL CLOUDS CONTINUE TO
DEVELOP IN A ZONE OF WARM ADVECTION ACROSS THE ILLINOIS RIVER
VALLEY. HIGH-RES MODELS SUCH AS THE HRRR AND 4KM WRF-NMM SUGGEST
SCT SHOWERS WILL DEVELOP IN THIS AREA DURING THE AFTERNOON. BASED
ON THE 12Z KILX UPPER AIR SOUNDING SHOWING VERY DRY AIR BELOW
10000FT...THINK CHANCES OF ANY PRECIP REACHING THE GROUND ARE SLIM
TO NONE. WILL THEREFORE CONTINUE WITH A DRY FORECAST TODAY.
INCREASED CLOUD COVER WEST OF I-55...BUT CONTINUED WITH SUNNY
SKIES FURTHER EAST AND SOUTH. TEMPS SEEM TO BE RIGHT ON
TARGET...WITH AFTERNOON HIGHS REACHING THE LOWER 90S ACROSS THE
BOARD. ONLY MINOR CHANGES MADE TO GRIDS...SO ZONE UPDATE IS NOT
NEEDED AT THIS TIME.
BARNES
&&
.AVIATION...
ISSUED 638 AM CDT THU AUG 23 2012
VFR CONDITIONS WILL CONTINUE AT ALL TAF SITES NEXT 24HRS. ANY
CLOUDS TODAY AND TONIGHT WILL BE SCATTERED MID CLOUDS AND
SCATTERED TO BROKEN HIGH CIRRUS. LIGHT AND VARIABLE WINDS THIS
MORNING WILL BECOME SOUTHERLY TODAY AND THEN SOUTHEAST THIS
EVENING AROUND SUNSET.
AUTEN
&&
.PREV DISCUSSION...
ISSUED 306 AM CDT THU AUG 23 2012
FORECAST NOT MUCH OF A SHIFT FROM YESTERDAY. WEAK FLOW ALOFT OVER
THE MIDWEST WITH THE MAJORITY OF THE UPPER WAVE ACTIVITY NORTH OF
THE REGION. WITH THE LACK OF SIGNIFICANT FLOW...THE WARM AIR FROM
THE WESTERN HALF OF THE CONUS IS LEAKING INTO THE MIDWEST AT
MIDLEVELS OF THE ATMOSPHERE BRINGING ANOTHER BRIEF ROUND OF HOT
WEATHER FOR THE FORECAST THROUGH THE END OF THE WEEK. NEXT SYSTEM
ON APPROACH FOR THE LATTER HALF OF THE WEEKEND STILL A BIT OF A
CONUNDRUM FOR THE MODELS...WITH GFS A GENERAL MESS WITH AN OPEN
AND DIFFUSE WAVE STIRRING UP WAY TOO MUCH QPF... AND THE ECMWF
OVER DEVELOPING THE SURFACE SYSTEM WITH DYNAMICS UPSTAIRS A LITTLE
LACKING. FORECAST RESULTS VERY SIMILAR TO YESTERDAY.
SHORT TERM...TODAY AND TOMORROW...
HOT AND HOT...TEMPS AT 850 MB IN THE 19-20C RANGE BRINGING HIGH
TEMPS INTO THE 90S. MID AND HIGH LEVEL CLOUDS EXPECTED TO MOVE OUT...PLENTY
OF SUNSHINE IN PLACE FOR THE MAJORITY OF THE DAY AND A RATHER DRY
AIR COLUMN. SAME STORY FOR TOMORROW EXPECTED. DRY AND HOT. WILL
HAVE TO KEEP AN EYE ON RH VALUES FOR FIRE WEATHER CONCERNS. FOR
NOW...ABOVE RED FLAG CRITERIA AND RATHER WEAK WINDS...BUT THE
HEIGHTENED CONCERN FOR OUTDOOR BURNING CONTINUES IN THE WIDESPREAD
DROUGHT.
LONG TERM...SATURDAY THROUGH THURSDAY...
ALMOST THE SAME EXACT STORY AS YESTERDAY. SATURDAY IS ANOTHER HOT
DAY... POTENTIALLY TEMPERED A BIT BY APPROACHING CLOUD COVER LATE
IN THE DAY. GFS A BIT TOO WET WITH NEXT SYSTEM FOR THE SECOND HALF
OF THE WEEKEND...THE ECMWF A LITTLE TOO WOUND UP...AND TRACKING
THE OPEN WAVE ALOFT IS ALL OVER THE PLACE. GFS LOSING ITS SFC LOW
REPRESENTATION A BIT AND INSTEAD LOOKING FOR A MORE WIDESPREAD
ASCENT ALONG A SFC TROF...WHICH MAKES A BIT MORE SENSE IN THE
WEAK DYNAMICS. ECMWF IS A LITTLE SLOWER AND MORE SOUTHERLY WITH THE
BEGINNING OF THE DEVELOPMENT OF THE SYSTEM...NOT STRINGING OUT THE
ENERGY ALOFT...NOR ALONG A PRODUCTIVE SFC TROF...AND KEEPING THE SYSTEM
A BIT MORE COMPACT. ECMWF THEN OVERDOES IT A BIT INTO THE
MIDWEST...OVERDEEPENING THE SFC LOW SUN NIGHT WITH WEAK FLOW AND A
POS TILT TO THE WAVE IN THE FIRST PLACE. OPERATIONAL MODELS STILL
SHAKING OUT THE ACTUAL TRACK OF A WEAK SFC LOW WITH VERY LITTLE
FLOW ALOFT THIS FAR SOUTH. NAM/WRF FINALLY JOINING IN THE PARTY
FOR THE FORECAST AND COMING IN ON THE SIDE OF THE ECMWF FOR A
SLOWER START...AND IF ANYTHING...TRACKING THE SFC LOW A BIT TO THE
NORTH AND WEST ALONG THE MORE ACTIVE WAVE TRAIN. BEST CHANCES FOR
PRECIP WHERE THE SOLUTIONS CROSS...SUN NIGHT AND MONDAY.
HJS
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
931 AM CDT THU AUG 23 2012
.DISCUSSION...
917 AM CDT
MADE SOME MINOR EDITS TO THE SKY COVER/WEATHER GRIDS THROUGH THE
AFTERNOON...TO ACCOUNT FOR PERSISTENT PARTLY CLOUDY/PARTLY SUNNY
SKIES AND POSSIBLE SCATTERED SPRINKLES.
LATEST SATELLITE IMAGERY SHOWING AREA OF MID LEVEL CLOUD COVER
ACROSS NORTHERN ILLINOIS SLOWLY SHIFTING EAST...BUT WITH CLOUD
COVER CONTINUING TO DEVELOP ACROSS THE WESTERN FRINGE OF THIS
CLOUD SHIELD. LATEST RUC ANALYSIS INDICATING WAA CONTINUING ACROSS
NORTHERN ILLINOIS...WITH THE SHOWERS OBSERVED THIS MORNING PARTLY
DUE TO THIS WEAK ASCENT. AS A MID LEVEL WAVE SHIFTS TO THE EAST
ACROSS THE MIDWEST...WAA SHOULD CONTINUE INTO THE AFTERNOON WITH
EVEN SOME OF THE SHORT RANGE GUIDANCE INDICATING THIS POSSIBILITY.
THE LATEST HRRR IS SHOWING SOME SCATTERED SHOWER DEVELOPMENT FOR
THE REMAINDER OF THE DAY MAINLY FOR AREAS ALONG AND NORTH OF LINE
FROM PONTIAC TO CHICAGO. WITH THIS WEAK ASCENT EXPECTED IN THIS
GENERAL AREA AS WELL AS LATEST VISIBLE IMAGERY ALREADY SHOWING A
CUMILIFORM NATURE TO THE CLOUD DEVELOPMENT ACROSS EASTERN IOWA AND
WESTERN ILLINOIS...FELT IT WAS AT LEAST POSSIBLE FOR SCATTERED
SPRINKLES AND HAVE INCLUDED THIS POSSIBILITY IN THE FORECAST
THROUGH THIS AFTERNOON. DESPITE WEAK INSTABILITY IN
PLACE...FORCING SHALL BE WEAK ENOUGH FOR THUNDER TO BE
NONEXISTENT TODAY.
RODRIGUEZ
&&
.PREV DISCUSSION...
303 AM CDT
THE WARMING TREND WILL CONTINUE INTO THE WEEKEND AND OVERALL
CONDITIONS LOOK TO BE DRY FOR THE NEXT SEVERAL DAYS...BUT THERE ARE
SEVERAL SUBTLETIES THAT COULD POINT TO SOME SPOTTY PRECIP
DEVELOPMENT BEFORE A WELL ORGANIZED SYSTEM ARRIVES SOMETIME SUNDAY.
MORNING MOISTURE CHANNEL IMAGERY SHOWS A LONGWAVE UPPER TROUGH AXIS
NOW PUSHING OFF THE EASTERN SEABOARD. MORE OF A ZONAL WEST TO EAST
FLOW IS SITUATED ACROSS THE NORTHERN CORRIDOR OF THE U.S. BUT THERE
ARE SEVERAL WEAK TROUGHS AND RIDGES EMBEDDED WITHIN THIS FLOW. THE
MORE NOTABLE FEATURES INCLUDE AN UPPER LOW LIFTING NORTHEASTWARD
ACROSS SASKATCHEWAN WITH AN ASSOCIATED TROUGH AXIS EXTENDING INTO
THE CENTRAL DAKOTAS...WHICH HAS FORCED WEAK RIDGING OUT AHEAD OF IT
WHICH DAMPENS OUT JUST TO THE WEST OF THE LOCAL AREA. A LARGE CLOSED
UPPER LOW IS NOW SPINNING OVER THE BRITISH COLUMBIA COAST WHILE A
CUTOFF LOW IS SLOWLY WORKING TOWARD THE FOUR CORNERS REGION. THESE
TWO SYSTEMS WILL BE THE PRIMARY FOCUS FOR PRECIP CHANCES LATER IN
THE WEEKEND. AT THE SURFACE...THE HIGH PRESSURE WHICH HAS DOMINATED
OUR LOCAL WEATHER THE PAST FEW DAYS HAS SHIFTED EASTWARD ACROSS THE
MID ATLANTIC REGION. ELONGATED LOW PRESSURE STRETCHES FROM CENTRAL
SASKATCHEWAN INTO WESTERN MINNESOTA AND INTO THE CENTRAL PLAINS IN
RESPONSE TO THE LOW AMPLITUDE TROUGH AXIS MENTIONED ABOVE.
TODAY THROUGH SATURDAY...THE DAMPENED UPPER RIDGING WILL CROSS THE
AREA THIS MORNING WITH MID LEVEL WARM ADVECTION ALREADY UNDERWAY. A
WEAK TROUGH FOLLOWS THE RIDGE INTO EARLY AFTERNOON BUT IS SLIGHTLY
MORE AMPLIFIED TO THE NORTH. IN ADDITION TO SOME INCREASED MID AND
HIGH CLOUD COVER SOME SCATTERED SPRINKLES ARE MOVING ACROSS THE AREA
AT THE CURRENT TIME BUT THESE WILL PROBABLY END BY MID MORNING.
CLOUD COVER APPEARS TO THIN THIS AFTERNOON...ESPECIALLY
WEST...ALLOWING FOR A DECENT AMOUNT OF SUNSHINE. WITH THE HIGH
MOVING OFF TO THE EAST THE PRESSURE GRADIENT WILL BE STRONGER THAN
PREVIOUS DAYS SUPPORTING A SOUTHERLY BREEZE. BETWEEN THE INCREASING
SUNSHINE...WARMER MID LEVELS...AND A SOUTH WIND...HIGHS WILL BE
WARMER THAN WEDNESDAY WITH READINGS IN THE UPPER 80S TO AROUND
90...WITH THE WARMEST READINGS WEST. FRIDAY...THE TROUGH WORKING
ACROSS SASKATCHEWAN/CENTRAL DAKOTAS THIS MORNING WILL MOVE ACROSS
THE AREA MIDDAY FRIDAY. THIS TROUGH WILL BE PRETTY STRETCHED OUT AND
LIFTING NORTHEASTWARD SO FORCING WILL BE PRETTY WEAK THIS FAR SOUTH.
AT THIS POINT SEE LITTLE SUPPORT FOR ORGANIZED SHOWER ACTIVITY SO
WILL GO WITH A DRY FORECAST. FRIDAY HIGHS SHOULD BE SLIGHTLY
WARMER THAN TODAY WITH MOST IF NOT ALL AREAS REACHING 90. SATURDAY
SHOULD BE A DRY DAY WITH HIGHS RIGHT AROUND THOSE OBSERVED FRIDAY.
SUNDAY THROUGH WEDNESDAY...THE CLOSED UPPER LOW CURRENTLY OVER THE
BRITISH COLUMBIA COAST WILL BE MOVING ACROSS CENTRAL/SOUTHERN
MANITOBA SATURDAY NIGHT. THE MAIN QUESTION IS HOW MUCH THE UPPER LOW
CURRENTLY APPROACHING THE FOUR CORNERS PHASES WITH THIS NORTHERN
STREAM SYSTEM. THE GFS AND ECMWF CONTINUE TO HAVE DIFFERENCES IN
THE MAGNITUDE OF PHASING AND ARE THEREFORE DIFFERENT WITH RESPECT
TO WHEN THIS SYSTEM CROSSES THE AREA. THE ECMWF IS LESS PHASED AND
THEREFORE KEEPS THE SOUTHERN STREAM TROUGH STRONGER WITH A BETTER
ORGANIZED SURFACE LOW ACCOMPANYING IT AS IT MOVES ACROSS THE MID
MISSISSIPPI RIVER VALLEY SUNDAY. THE GFS IS FASTER AND HAS THE
UPPER TROUGH PHASED TO A GREATER DEGREE. STILL PREFER THE ECMWF
OVERALL THOUGH IT IS JUST A BIT FASTER THAN EARLIER RUNS. THE 00Z
RUN WHICH HAS JUST ARRIVED IS SLIGHTLY MORE PHASED THAN THE 12Z
RUN BUT THE TIMING OF THE SYSTEM IS ABOUT THE SAME. THIS RESULTS
IN RAIN/THUNDER CHANCES SPREADING FROM WEST TO EAST SUNDAY AND
EXITING SOMETIME MONDAY. THE UPPER FLOW PATTERN WILL AMPLIFY AS
THIS SYSTEM MOVES EASTWARD WITH A LARGE RIDGE BUILDING TO THE
WEST. THIS WILL LEAVE THE AREA UNDER A NORTHWESTERLY UPPER FLOW
WHICH WILL ALLOW COOLER AIR TO SPREAD IN FROM THE NORTH MONDAY
NIGHT. FROM THAT POINT ON OUR WEATHER WILL BE DRIVEN BY HOW
PROGRESSIVE THE UPPER FLOW PATTERN BECOMES THROUGH THE REST OF
NEXT WEEK ALONG WITH INTERACTION BETWEEN IT AND TROPICAL SYSTEM
ISAAC WHICH WILL LIKELY BE ENTERING THE GULF OF MEXICO BY EARLY
NEXT WEEK.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* SCATTERED SHOWERS LIKELY. CHANCES OF IMPACTING TERMINALS SMALL.
* INCREASING SOUTHERLY WINDS BECMG 10KT GUSTING TO 15KT THIS AFTERNOON.
KREIN
//DISCUSSION...UPDATED 12Z...
MAIN ISSUE THIS MORNING IS SOME SCATTERED SHOWERS FALLING FROM A
MID LEVEL CLOUD DECK. CLOUD BASES ACROSS THE REGION ARE BETWEEN
10KFT AND 15KFT...SO ANY PCPN HITTING THE GROUND SHOULD BE LIGHT.
LATEST RADAR IMAGERY SHOWS SOME HEAVIER SHOWERS TO THE NORTH OF
ORD/DPA. THESE SHOWERS HAVE A SOUTHEASTERLY TRACK...AND THERE IS
THE CHANCE THAT ORD COULD BE IMPACTED...BUT ANY PCPN WOULD BE VERY
BRIEF. OTHERWISE...EXPECTING THAT THE MID CLOUD DECK SHOULD BEGIN
TO MOVE OUT THIS AFTERNOON...LEAVE NO SIG CLOUD COVER. THE ONLY
OTHER CONCERN TODAY WILL BE WINDS. WINDS HAVE BEEN LIGHT AND
SOUTHERLY THROUGH THE NIGHT...BUT SHOULD BE INCREASING THROUGH THE
MORNING...BUT MAINTAINING A SOUTHERLY DIRECTION. EXPECT SPEEDS OF
10KT WITH OCNL GUSTS TO 15KT THIS AFTERNOON.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM TO HIGH CONFIDENCE IN TRENDS AND TRACK OF SHRA.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...VFR. WX NIL.
SATURDAY...VFR. WX NIL.
SUNDAY...CHANCE TSRA. OTHERWISE...VFR.
MONDAY...CHANCE TSRA EARLY. OTHERWISE...VFR.
TUESDAY...VFR. WX NIL.
WEDNESDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
250 AM CDT
HIGH PRESSURE EXTENDING FROM NEW ENGLAND SOUTHWESTWARD TO THE
TEXAS GULF COAST WILL REMAIN NEARLY STATIONARY THROUGH
SUNDAY...WHILE A WEAK TROUGH OF LOW PRESSURE EXTENDS FROM
MANITOBA THROUGH THE CENTRAL PLAINS. THIS WILL KEEP SOUTHERLY
WINDS OF AROUND 15-20KT...OCCASIONALLY TO AROUND 25 KT...OVER THE
LAKE. A STRENGTHENING LOW PRESSURE SYSTEM WILL DROP OUT OF THE
CANADIAN ROCKIES AND MOVE OUT OVER SOUTHERN MANITOBA SATURDAY.
THIS LOW WILL TRACK NORTHEAST TO HUDSON BAY BY SUNDAY NIGHT WHILE
DRAGGING A COLD FRONT ACROSS THE WESTERN GREAT LAKES
REGION...TURNING WINDS OVER LAKE MICHIGAN TO WESTERLY OR
NORTHWESTERLY BY SUNDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1215 PM CDT THU AUG 23 2012
.AVIATION...
VFR WX WILL BE SEEN THROUGH 00Z/25. DENSITY ALTITUDES MAY
APPROACH 3KFT THROUGH 00Z/24. THE MODELS ARE SUGGESTING THE
POTENTIAL FOR LLWS AFT 06Z/24. HOWEVER...THE CORE OF THE STRONGER
WINDS GENERALLY REMAIN IN CENTRAL IOWA. THUS THE POTENTIAL FOR
LLWS APPEARS MARGINAL FOR KCID/KDBQ. LLWS IS NOT EXPECTED AT
KMLI/KBRL. ..08..
&&
.PREV DISCUSSION... /ISSUED 1043 AM CDT THU AUG 23 2012/
UPDATE...
A VERY MINOR UPDATE TO THE FCST HAS BEEN DONE TO HAVE IT REFLECT
CURRENT TRENDS.
SATELLITE SHOW CLOUDS OVER THE IMMEDIATE AREA ARE SLOWLY
DISSIPATING. THE CLOUDS OVER NORTHEAST ILLINOIS/EASTERN WISCONSIN
ARE BEING DRIVEN IN RESPONSE TO A VORT MAX MOVING THROUGH THE
AREA. RAP TRENDS SHOW LIFT INCREASING AGAIN LATE MORNING/AFTERNOON
AS A WEAKER VORT MAX MOVES INTO EASTERN IOWA. FCST SOUNDINGS
CONTINUE TO SHOW A DRY ATMOSPHERE BELOW 700MB SO ANY CLOUDS THAT
DEVELOP SHOULD BE IN THE 10-15 THOUSAND AGL RANGE BUT MID LEVEL
LAPSE RATES ARE MARGINAL. FCST SOUNDINGS DO SHOW MOISTURE ABOVE
THE LFC SO THERE IS THE POSSIBILITY OF THESE CLOUDS BEING ACCAS
WITH PERHAPS VIRGA.
MAX TEMPERATURES WERE RAISED SLIGHTLY IN THE SOUTHWEST CWFA BASED
ON WARMER READINGS THERE AT 15Z. IT WILL BE A VERY WARM DAY BUT
MIXING SHOULD ALLOW THE MID AND UPPER 50 DEW POINTS TO DROP INTO
THE UPPER 40S TO NEAR 55 DURING THE AFTERNOON. ..08..
PREV DISCUSSION... /ISSUED 333 AM CDT THU AUG 23 2012/
SYNOPSIS...
THE UA ANALYSIS SHOWED NEAR ZONAL H5 FLOW IN PLACE OVER THE
WESTERN HALF OF THE U.S. SURFACE FEATURES EARLY THIS MORNING
INCLUDE LOW PRESSURE OVER EASTERN SD WITH A WARM FRONT EXTENDING
SOUTHEAST THROUGH NRN IA AND NORTHERN IL. A S/W OVER SD IN THE
WESTERLY FLOW WAS SUPPORT AN AREA OF SHRA/TSRA OVER EASTERN
SD/WESTERN MN EARLY THIS MORNING. FURTHER DOWN STREAM ELEVATED WAA
WAS RESULTING IN SOME HIGH BASED AC WITH SOME SPOTTY RETURNS ON
RADAR OVER NORTHEAST IA AND NRN IL. SO FAR SURFACE OBS UNDER THE
PRECIP HAVE NOT SHOWN ANY RAIN REPORTS...SO THE PCPN IS PROBABLY
EVAPORATING BEFORE REACHING THE GROUND.
SHORT TERM...TODAY AND TONIGHT...
THE NORTHERN PLAINS SW WILL CONTINUE EAST TODAY WITH THE BETTER
FORCING WITH THE WAVE STAYING WELL NORTH OF THE CWFA. THIS SHOULD
KEEP THE CLUSTER OF SHRA/TSRA JUST AHEAD OF WAVE MAINLY OVER MN
AND WI TODAY AND TONIGHT. THE AREA OF MID CLOUD/VIRGA WILL BE SLOW
TO MOVE OFF TO THE EAST TODAY. THE DEEP LAYER OF DRY AIR BELOW THE
CLOUD BASE THOUGH SHOULD CONTINUE TO CAUSE ANY PRECIPITATION TO
EVAPORATE SO WILL KEEP THE FORECAST DRY FOR TODAY. MODEL SOUNDINGS
SHOW A NEARLY DRY ADIABATIC LAPSE THROUGH 700MB TODAY INDICATING
DEEP MIXING. THIS SHOULD DRIVE TEMPERATURES INTO THE LOW TO MID
90S.
TONIGHT MODELS SHOW SHRA/TSRA ASSOCIATED WITH THE MN S/W MOVING
THROUGH THE NW HALF OF IA BUT DISSIPATING BEFORE REACHING THE EAST
CENTRAL AND SOUTHEAST COUNTIES. WILL KEEP THE FORECAST DRY
OVERNIGHT BUT WE SHOULD SEE...BLOW OFF CLOUDS...FROM THE
CONVECTION TO THE WEST SPREADING OVER THE CWFA. THE HIGH CLOUDS
AND LIGHT SOUTH WINDS WILL KEEP OVERNIGHT LOW IN THE MID 60S.
DLF
LONG TERM...FRIDAY THROUGH WEDNESDAY...
WARM...BREEZY AND DRY WEATHER CONTINUES FRIDAY THROUGH MUCH OF
SATURDAY...THEN FOCUS TURNS TO SYSTEM WITH POTENTIAL FOR SIGNIFICANT
RAINFALL LATE SATURDAY THROUGH SUNDAY.
MODEL FORECAST SOUNDINGS...OUTSIDE THE GFS WITH ITS CONTINUED POOR
HANDLING OF LOW LEVEL THERMAL AND MOISTURE FIELDS...SUGGEST ANOTHER
DAY OF DEEP MIXING TO AT LEAST 700 MB IN THE DRY LOW LEVEL SOUTHERLY
FLOW ON FRIDAY. THIS WOULD PLACE HIGHS AGAIN INTO THE LOWER TO MID 90S
WITH DEWPOINTS MIXING OUT INTO THE 50S...IF NOT UPPER 40S...AS THE
MONSOONAL MOISTURE AND HIGHER PW VALUES DO NOT LOOK TO REACH THE
AREA UNTIL FRIDAY NIGHT AT THE EARLIEST. A LIGHT S-SE LOW LEVEL FLOW
OVERNIGHT SHOULD HOLD MINS TO NO LOWER THAN THE 60S.
SATURDAY...MOISTURE ADVECTION AND FORCING AHEAD OF A MID LEVEL
SHORTWAVE MAY TRIGGER THUNDERSTORMS OVER THE WEST AND HAVE CHANCE
POPS IN PLACE. THIS WILL LIMIT HIGHS TO THE MID AND UPPER
80S...WHILE EAST OF THE MS RIVER REMAINS DRY AND REACHES CLOSER TO
90.
SATURDAY NIGHT INTO SUNDAY...A COMPLEX SYSTEM WILL PUSH THROUGH THE
AREA WITH ABUNDANT AVAILABLE MOISTURE TO PRODUCE WIDESPREAD
RAINFALL. WHILE DETAILS STILL VARY AMONG MODELS...ESPECIALLY WITH
RESPECT TO THE PLACEMENT AND TIMING OF A WEAK LOW LEVEL CIRCULATION
PASSING TO THE SOUTH...THERE IS ENOUGH AGREEMENT AND CONSISTENCY TO
JUSTIFY LIKELY POPS FOR SUNDAY. GFS AND ECMWF MODEL QPF TOTALS
CONTINUE TO PAINT WIDESPREAD 1 TO 2 INCH EVENT TOTALS FOR THE
REGION. HIGHS HAVE BEEN TRIMMED BACK TO THE UPPER 70S TO LOWER
80S...WHICH MAY STILL BE TOO WARM IF CLOUDS AND RAIN PREVAIL.
MONDAY THROUGH WEDNESDAY GENERALLY LOOKS DRY WITH NEAR TO ABOVE
NORMAL TEMPERATURES AS AN UPPER LEVEL RIDGE BUILDS TO THE WEST WITH
SURFACE HIGH PRESSURE OVER THE REGION.
SHEETS
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1043 AM CDT THU AUG 23 2012
.UPDATE...
A VERY MINOR UPDATE TO THE FCST HAS BEEN DONE TO HAVE IT REFLECT
CURRENT TRENDS.
SATELLITE SHOW CLOUDS OVER THE IMMEDIATE AREA ARE SLOWLY
DISSIPATING. THE CLOUDS OVER NORTHEAST ILLINOIS/EASTERN WISCONSIN
ARE BEING DRIVEN IN RESPONSE TO A VORT MAX MOVING THROUGH THE
AREA. RAP TRENDS SHOW LIFT INCREASING AGAIN LATE MORNING/AFTERNOON
AS A WEAKER VORT MAX MOVES INTO EASTERN IOWA. FCST SOUNDINGS
CONTINUE TO SHOW A DRY ATMOSPHERE BELOW 700MB SO ANY CLOUDS THAT
DEVELOP SHOULD BE IN THE 10-15 THOUSAND AGL RANGE BUT MID LEVEL
LAPSE RATES ARE MARGINAL. FCST SOUNDINGS DO SHOW MOISTURE ABOVE
THE LFC SO THERE IS THE POSSIBILITY OF THESE CLOUDS BEING ACCAS
WITH PERHAPS VIRGA.
MAX TEMPERATURES WERE RAISED SLIGHTLY IN THE SOUTHWEST CWFA BASED
ON WARMER READINGS THERE AT 15Z. IT WILL BE A VERY WARM DAY BUT
MIXING SHOULD ALLOW THE MID AND UPPER 50 DEW POINTS TO DROP INTO
THE UPPER 40S TO NEAR 55 DURING THE AFTERNOON. ..08..
&&
.PREV DISCUSSION... /ISSUED 617 AM CDT THU AUG 23 2012/
AVIATION...
A SURFACE TROF OVER THE CENTRAL AND NORTHERN PLAINS WILL MOVE
SLOWLY EAST TODAY AND TONIGHT KEEPING SOUTHERLY WINDS OVER THE
FORECAST AREA THROUGH TONIGHT. VFR CONDITIONS WILL REMAIN OVER
THE AREA THROUGH THE PERIOD. SOME SPOTTY ELEVATED SHRA WILL BE
ASSOCIATED WITH SOME SCATTERED TO BROKEN MID CLOUDS ESPECIALLY
EAST OF THE MISSISSIPPI RIVER. SINCE THE AIR BELOW THE CLOUD
BASES WILL REMAIN DRY...ANY RAIN SHOULD EVAPORATE BEFORE REACHING
THE GROUND. THUNDERSTORMS WILL BE MOVING THROUGH THE NW HALF OF
IOWA TONIGHT. THESE STORMS SHOULD REMAIN WELL WEST OF THE ALL TAF
SITES THROUGH 12Z FRIDAY.
DLF
PREV DISCUSSION... /ISSUED 333 AM CDT THU AUG 23 2012/
SYNOPSIS...
THE UA ANALYSIS SHOWED NEAR ZONAL H5 FLOW IN PLACE OVER THE
WESTERN HALF OF THE U.S. SURFACE FEATURES EARLY THIS MORNING
INCLUDE LOW PRESSURE OVER EASTERN SD WITH A WARM FRONT EXTENDING
SOUTHEAST THROUGH NRN IA AND NORTHERN IL. A S/W OVER SD IN THE
WESTERLY FLOW WAS SUPPORT AN AREA OF SHRA/TSRA OVER EASTERN
SD/WESTERN MN EARLY THIS MORNING. FURTHER DOWN STREAM ELEVATED WAA
WAS RESULTING IN SOME HIGH BASED AC WITH SOME SPOTTY RETURNS ON
RADAR OVER NORTHEAST IA AND NRN IL. SO FAR SURFACE OBS UNDER THE
PRECIP HAVE NOT SHOWN ANY RAIN REPORTS...SO THE PCPN IS PROBABLY
EVAPORATING BEFORE REACHING THE GROUND.
SHORT TERM...TODAY AND TONIGHT...
THE NORTHERN PLAINS SW WILL CONTINUE EAST TODAY WITH THE BETTER
FORCING WITH THE WAVE STAYING WELL NORTH OF THE CWFA. THIS SHOULD
KEEP THE CLUSTER OF SHRA/TSRA JUST AHEAD OF WAVE MAINLY OVER MN
AND WI TODAY AND TONIGHT. THE AREA OF MID CLOUD/VIRGA WILL BE SLOW
TO MOVE OFF TO THE EAST TODAY. THE DEEP LAYER OF DRY AIR BELOW THE
CLOUD BASE THOUGH SHOULD CONTINUE TO CAUSE ANY PRECIPITATION TO
EVAPORATE SO WILL KEEP THE FORECAST DRY FOR TODAY. MODEL SOUNDINGS
SHOW A NEARLY DRY ADIABATIC LAPSE THROUGH 700MB TODAY INDICATING
DEEP MIXING. THIS SHOULD DRIVE TEMPERATURES INTO THE LOW TO MID
90S.
TONIGHT MODELS SHOW SHRA/TSRA ASSOCIATED WITH THE MN S/W MOVING
THROUGH THE NW HALF OF IA BUT DISSIPATING BEFORE REACHING THE EAST
CENTRAL AND SOUTHEAST COUNTIES. WILL KEEP THE FORECAST DRY
OVERNIGHT BUT WE SHOULD SEE...BLOW OFF CLOUDS...FROM THE
CONVECTION TO THE WEST SPREADING OVER THE CWFA. THE HIGH CLOUDS
AND LIGHT SOUTH WINDS WILL KEEP OVERNIGHT LOW IN THE MID 60S.
DLF
LONG TERM...FRIDAY THROUGH WEDNESDAY...
WARM...BREEZY AND DRY WEATHER CONTINUES FRIDAY THROUGH MUCH OF
SATURDAY...THEN FOCUS TURNS TO SYSTEM WITH POTENTIAL FOR SIGNIFICANT
RAINFALL LATE SATURDAY THROUGH SUNDAY.
MODEL FORECAST SOUNDINGS...OUTSIDE THE GFS WITH ITS CONTINUED POOR
HANDLING OF LOW LEVEL THERMAL AND MOISTURE FIELDS...SUGGEST ANOTHER
DAY OF DEEP MIXING TO AT LEAST 700 MB IN THE DRY LOW LEVEL SOUTHERLY
FLOW ON FRIDAY. THIS WOULD PLACE HIGHS AGAIN INTO THE LOWER TO MID 90S
WITH DEWPOINTS MIXING OUT INTO THE 50S...IF NOT UPPER 40S...AS THE
MONSOONAL MOISTURE AND HIGHER PW VALUES DO NOT LOOK TO REACH THE
AREA UNTIL FRIDAY NIGHT AT THE EARLIEST. A LIGHT S-SE LOW LEVEL FLOW
OVERNIGHT SHOULD HOLD MINS TO NO LOWER THAN THE 60S.
SATURDAY...MOISTURE ADVECTION AND FORCING AHEAD OF A MID LEVEL
SHORTWAVE MAY TRIGGER THUNDERSTORMS OVER THE WEST AND HAVE CHANCE
POPS IN PLACE. THIS WILL LIMIT HIGHS TO THE MID AND UPPER
80S...WHILE EAST OF THE MS RIVER REMAINS DRY AND REACHES CLOSER TO
90.
SATURDAY NIGHT INTO SUNDAY...A COMPLEX SYSTEM WILL PUSH THROUGH THE
AREA WITH ABUNDANT AVAILABLE MOISTURE TO PRODUCE WIDESPREAD
RAINFALL. WHILE DETAILS STILL VARY AMONG MODELS...ESPECIALLY WITH
RESPECT TO THE PLACEMENT AND TIMING OF A WEAK LOW LEVEL CIRCULATION
PASSING TO THE SOUTH...THERE IS ENOUGH AGREEMENT AND CONSISTENCY TO
JUSTIFY LIKELY POPS FOR SUNDAY. GFS AND ECMWF MODEL QPF TOTALS
CONTINUE TO PAINT WIDESPREAD 1 TO 2 INCH EVENT TOTALS FOR THE
REGION. HIGHS HAVE BEEN TRIMMED BACK TO THE UPPER 70S TO LOWER
80S...WHICH MAY STILL BE TOO WARM IF CLOUDS AND RAIN PREVAIL.
MONDAY THROUGH WEDNESDAY GENERALLY LOOKS DRY WITH NEAR TO ABOVE
NORMAL TEMPERATURES AS AN UPPER LEVEL RIDGE BUILDS TO THE WEST WITH
SURFACE HIGH PRESSURE OVER THE REGION.
SHEETS
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1212 PM CDT THU AUG 23 2012
...UPDATED THE FOR THE 18Z AVIATION DISCUSSION AND SHORT TERM UPDATE...
.UPDATE...
ISSUED AT 1210 PM CDT THU AUG 23 2012
AFTER REVIEWING THE CURRENT CONDITIONS AND SHORT TERM MODELS SUCH
AS THE HRRR AND RAPID REFRESH MODELS, LOWERED POPS UNTIL AFTER 23Z
TODAY AND MOVED THE PRECIP FROM WEST TO EAST, SLOWLY RISING POPS
TONIGHT. ALSO, I ADDED THE MENTION OF POSSIBLE SEVERE WITH
DOWNBURST WINDS AND HEAVY RAIN IN THE NORTHERN ZONES, AFTER 23Z
AND UNTIL 04Z. THIS LAST UPDATE WAS MAINLY INFLUENCED BY THE DAY
ONE SPC CONVECTIVE OUTLOOK.
&&
.SYNOPSIS...
ISSUED AT 108 AM CDT THU AUG 23 2012
WV IMAGERY AND 00Z UPPER AIR ANALYSIS INDICATE A WEAK NORTHWEST
FLOW ALOFT ACROSS THE WESTERN HIGH PLAINS. MEANWHILE, A CLOSED OFF
UPPER LEVEL LOW IS TRACKING EASTWARD ACROSS SOUTHERN NEVADA. NEAR
THE SURFACE, A LEE SIDE TROUGH OF LOW PRESSURE IS SET UP ACROSS
EASTERN COLORADO. SURFACE DEWPOINTS ARE IN THE UPPER 50S(F) TO
THE LOWER 60S(F) ACROSS CENTRAL AND SOUTHWEST KANSAS.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 300 AM CDT THU AUG 23 2012
SHORT RANGE MODELS INDICATE THE CLOSED OFF UPPER LEVEL LOW PUSHING
SLOWLY EAST INTO THE FOUR CORNERS REGION TODAY. MEANWHILE, A
DOWNSTREAM UPPER LEVEL SHORTWAVE IS PROJECTED TO EJECT EAST OUT OF
THE ROCKIES THIS MORNING AND INTO THE WESTERN HIGH PLAINS OF WESTERN
NEBRASKA AND NORTHEASTERN COLORADO THIS AFTERNOON. THIS WILL SET THE
STAGE FOR POSSIBLE SHOWER AND THUNDERSTORM DEVELOPMENT INTO
PORTIONS OF WESTERN KANSAS LATER TODAY AS LOW LEVEL MOISTURE
CONTINUES TO ADVECT NORTHWARD OUT OF THE TEXAS AND OKLAHOMA
PANHANDLES. NAM AND GFS MODEL SOUNDINGS SUGGEST INCREASED
INSTABILITY LEVELS INTO THIS AFTERNOON WITH CAPE VALUES IN THE
ORDER OF 1500 TO 2000 J/KG ACROSS CENTRAL AND EASTERN PORTIONS OF
SOUTHWEST KANSAS WHILE LOW/MID LEVEL LAPSE RATES STEEPEN WITH
DAYTIME HEATING. ADDITIONAL SUPPORT COULD COME LATE THIS AFTERNOON
AND EVENING AS A LOW LEVEL JET DEVELOPS ACROSS THE SAME GENERAL
AREA AHEAD OF A STRENGTHENING SURFACE LOW IN SOUTHEASTERN
COLORADO. HOWEVER, ALL MODELS INDICATE THE FLOW ALOFT REMAINING
FAIRLY WEAK ALONG WITH MODEST VERTICAL SHEAR AT BEST. THIS MAY
LIMIT THE COVERAGE AND STRENGTH OF ANY DEVELOPING SHOWERS AND
THUNDERSTORMS AS THE UPPER LEVEL SHORTWAVE KICKS OUT. STILL, THE
BEST CHANCE FOR PRECIP LOOKS TO BE ACROSS CENTRAL AND EASTERN
PORTIONS OF WESTERN KANSAS WHERE THE BEST LOW LEVEL LIFT WILL
LIKELY BE IN RESPECT TO THE SURFACE LOW...AND IN CONJUNCTION WITH
THE EXPECTED DEVELOPMENT OF A LOW LEVEL JET. ALTHOUGH WIDESPREAD
SEVERE WEATHER IS NOT EXPECTED, ENOUGH INSTABILITY EXISTS THAT A
FEW STORMS COULD BECOME FAIRLY STRONG CAPABLE OF PRODUCING GUSTY
WINDS IN EXCESS OF 40 TO 50 MPH AND POSSIBLE NICKEL TO QUARTER SIZE
HAIL. AREAS OF LOCALLY HEAVY RAIN MAY OCCUR AS WELL WITH NAM/GFS
MODEL SOUNDINGS SHOWING PW VALUES IN EXCESS OF 1.5 INCHES. WILL
INCREASE CHANCE CATEGORY POPS UP TO LOW END LIKELY CATEGORY POPS
GENERALLY ACROSS CENTRAL KANSAS FOR TONIGHT PER REASONS DISCUSSED
EARLIER.
TEMPERATURES ARE EXPECTED TO BE NEAR NORMAL TODAY AS LEE SIDE
TROUGHING CONTINUES TO HELP INFLUENCE A LOW LEVEL SOUTHERLY FLOW
ACROSS WESTERN KANSAS. THIS WILL ENHANCE WARM AIR ADVECTION INTO
THE AREA WITH H85 TEMPERATURES CLIMBING SLIGHTLY OVER YESTERDAY
WITH VALUES IN THE LOWER TO MID 20S(C) ACROSS CENTRAL KANSAS TO
THE UPPER 20S(C) IN FAR SOUTHWEST KANSAS. ALTHOUGH INCREASED
CLOUDS MAY HINDER CLIMBING TEMPERATURES A LITTLE, HIGHS ARE STILL
EXPECTED TO RANGE ANYWHERE FROM THE UPPER 80S(F) TO THE LOWER TO
MID 90S(F) THIS AFTERNOON. EXPECT LOWS DOWN INTO THE 60S(F) FOR
THE MOST PART ONCE AGAIN TONIGHT, PARTICULARLY WITH AREAS OF
PRECIP ABOUT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 205 AM CDT THU AUG 23 2012
A WET PERIOD...WHICH WILL COMMENCE LATER ON TODAY...WILL CONTINUE
THROUGH LATE SATURDAY NIGHT/EARLY SUNDAY AS A VERY SLOW MOVING UPPER
LEVEL DISTURBANCE MOVES FROM THE DESERT SOUTHWEST THROUGH THE
SOUTHERN/CENTRAL ROCKIES AND ACROSS THE CENTRAL PLAINS. WHILE IT IS
VERY DIFFICULT TO FORECAST THE FINER SCALE ATMOSPHERIC MOTIONS WHICH
WILL DICTATE DAILY THUNDERSTORM COMPLEXES...THE INGREDIENTS WILL BE
IN PLACE FOR SUSTAINED RAIN AND THUNDERSTORMS ACROSS A LARGE PORTION
OF THE FORECAST AREA THROUGH SATURDAY NIGHT. THESE INGREDIENTS
INCLUDE AN ABNORMALLY HIGH DEGREE OF ATMOSPHERIC MOISTURE (PWAT
VALUES AVERAGING 1.65 WAKEENEY-DODGE CITY LINE TO 1.85 INCHES AROUND
BARBER COUNTY, OR AROUND +2 STANDARD DEVIATION OF CLIMATOLOGICAL
NORMAL FOR DODGE CITY IN AUGUST) AND A SUSTAINED AXIS OF LOW LEVEL
CONVERGENCE AND DEFORMATION TIED TO THE UPPER LEVEL DISTURBANCE
ACROSS WESTERN KANSAS. OF COURSE...THESE LOW LEVEL BOUNDARIES WILL
BE AUGMENTED BY CONVECTIVE OUTFLOWS...BUT THERE IS NOT EXPECTED TO
BE A STRONG COLD FRONT THROUGH THIS ENTIRE PERIOD THAT WOULD REMOVE
THE MOISTURE FROM THE AREA...UNTIL LATE SATURDAY/SATURDAY
NIGHT...AND MORE LIKELY SUNDAY ACROSS SOUTH-CENTRAL KANSAS.
AS FAR AS THE GRIDS GO FOR 12-HR PERIOD POPS...THE PLAN IS TO KEEP
THE GOING FORECAST AS-IS FOR NOW...WHICH DOES INCLUDE LIKELY POPS
ACROSS MUCH OF SOUTHWEST-CENTRAL-SOUTH CENTRAL KS FRIDAY NIGHT INTO
SATURDAY...WITH 40-50 PERCENT CHANCE POPS SATURDAY NIGHT SOUTHEAST
OF A HAYS TO MEADE LINE. WHEN ALL IS SAID AND DONE BY THE END OF THE
WEEKEND...EVENT TOTAL PRECIPITATION IS EXPECTED TO BE ONE TO TWO
INCHES (PERHAPS LOCALLY HIGHER) OVER A PORTION OF CENTRAL, SOUTH
CENTRAL, AND SOUTHWEST KANSAS...ESPECIALLY SOUTHEAST OF AN ASHLAND
TO LARNED LINE. DAILY HIGH TEMPERATURES FRIDAY THROUGH SUNDAY ARE
EXPECTED TO BE IN THE MID TO UPPER 80S...BUT WILL ALSO BE SUBJECT TO
BUST POTENTIAL IN SOME AREAS FROM CONVECTIVE OUTFLOWS. UPPER LEVEL
RIDGING WILL BEGIN TO INFLUENCE WESTERN KANSAS SUNDAY WITH A DRYING
OUT PERIOD BEGINNING THEN. HIGHS SUNDAY THROUGH MID-NEXT WEEK WILL
GENERALLY BE IN THE UPPER 80S TO LOWER 90S UNDER THE INFLUENCE OF
UPPER LEVEL HIGH PRESSURE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1200 PM CDT THU AUG 23 2012
HIGH THIN CLOUDS AND BREEZY SOUTH WINDS WILL GIVE VFR CONDITION
THIS AFTERNOON AND INTO THE EVENING. A MESOCYLONE SYSTEM OF RAIN
WILL FORM IN NORTH CENTRAL KANSAS THIS EVENING AND COUPLE WITH A
SURFACE DRY LINE TO PRODUCE STORMS MOVING WEST TO EAST ACROSS THE
TAF SITE THIS EVENING. A FEW OF THE STORMS, ESPECIALLY IN THE KHYS
SITE, MAY PRODUCE HEAVY DOWNPOURS AND WIND GUSTS TO 50 KTS.
EXACTLY WHERE THE SEVERE STORMS WILL BE IS HARD TO PINPOINT, SO
ONLY PROB30 GROUPS WERE USED AT THIS TIME. AFTER ABOUT 09 TO 10Z,
THE CONVECTION SHOULD SLOW DOWN AND MOVE EAST.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 90 65 82 67 / 30 50 50 60
GCK 90 65 83 68 / 30 40 30 50
EHA 90 65 88 67 / 30 30 30 40
LBL 92 65 87 68 / 30 40 40 50
HYS 90 65 86 68 / 20 50 50 60
P28 90 67 83 68 / 20 50 50 60
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JJOHNSON
SHORT TERM...JJOHNSON
LONG TERM...UMSCHEID
AVIATION...BURKE
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
1002 AM EDT THU AUG 23 2012
.SYNOPSIS...
LOW PRESSURE WILL TRACK EASTWARD THROUGH CENTRAL QUEBEC THIS
MORNING...DRAGGING A COLD FRONT INTO THE MOUNTAINS TODAY. HIGH
PRESSURE WILL BUILD OVER NORTHERN NEW ENGLAND ON FRIDAY AND SHIFT
OFFSHORE THIS WEEKEND. GENERALLY DRY AND SEASONABLY WARM
CONDITIONS ARE EXPECTED THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATE...CIRRUS NOW MOVING ACROSS SOUTHERN NH AS MOISTURE SURGES
OUT AHEAD OF A MID LEVEL SHORT WAVE. OTHERWISE FOG HAS LIFTED AND
SKIES ARE CLEAR. TEMPERATURES ARE WARMING QUICKLY AND ARE A FEW
DEGREES WARMER THAN THEY WERE THIS TIME YESTERDAY. ADJUSTED
TEMPERATURES AND DEW POINTS SLIGHTLY BASED ON THESE TRENDS. ALSO
BASED ON THE LATEST RUN OF THE HRRR AND ONLY WEAK FRONTOGENESIS
PROGS REDUCED THE POPS FOR THIS AFTERNOON FROM CHANCE TO SLIGHT
CHANCE ACROSS OUR NORTHERN COUNTIES.
&&
PREVIOUS DISCUSSION...CLEAR SKIES AND LIGHT WINDS ARE MAKING FOR
ANOTHER COOL NIGHT AWAY FROM THE COAST. ALREADY SEEING PATCHY
GROUND FOG DEVELOPING IN THE USUAL COOL SPOTS AND RIVER VALLEYS.
EXPECT THE TREND TO CONTINUE FOR THE NEXT COUPLE OF HRS. WITH THE
DRIER AIR MASS IN PLACE...EARLY DAY SUNSHINE WILL QUICKLY PUSH
TEMPS UP AND THE FOG WILL LIFT OUT AS THEY DO.
ANOTHER PLEASANT DAY IN STORE TODAY...WITH TEMPS WARMER IN THE
80S. WAA AHEAD OF THE SRN CANADA S/WV TROF WILL INCREASE MID LVL
TEMPS IN SRN NH SUPPORTIVE OF A RUN AT THE UPR 80S. THIS S/WV WILL
BE SHEARING OUT WITH TIME AND LIFTING NEWD. THIS WILL JUST PROVIDE
A GLANCING BLOW OF WEAK FORCING TO NRN NEW ENGLAND. AS SUCH...HAVE
KEPT POP TIED TO THE HIGHER TERRAIN...WHERE THE ELEVATED HEAT
SOURCE WILL BE THE MOST LIKELY IMPETUS FOR CONVECTION.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
CONSIDERING THE SHRA/TSTMS THAT DO DEVELOP THIS AFTN WILL BE
MOSTLY DIURNALLY DRIVEN...EXPECT THAT THEY WILL WEAKEN QUICKLY
AFTER SUNSET. AS HIGH PRES BUILD BACK IN BEHIND SFC TROF...WILL
SEE MORE PATCHY FOG IN THE VALLEYS.
FRI WILL BE NICE AGAIN...WITH TEMPS SLIGHTLY COOLER THAN TODAY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
SURFACE HIGH PRESSURE PARKS ITSELF OVER NORTHERN NEW ENGLAND FOR
THE WEEKEND. THIS WILL BRING MILD SUNNY DAYS WITH AFTERNOON SEA
BREEZES ALONG THE COAST. DURING THE NIGHTTIME PERIODS...LOOK FOR
CHILLY CONDITIONS AND PATCHY FOG. STILL LOOKING FOR SOME MID TO
UPPER 40S IN THE MOUNTAINS.
A MORE SIGNIFICANT UPPER LEVEL TROUGH APPROACHES THE REGION BY
MONDAY NIGHT...ALLOWING A COLD FRONT TO SLIP THROUGH THE REGION
THROUGH TUESDAY MORNING. ALL MODELS AGREE THAT A FEW SCT SHOWERS
OR PSBLY A TSTM WILL CROSS THE REGION WITH THIS SYSTEM AS IT
RIDES THROUGH. OVERALL HOWEVER...DRY CONDS WILL CONTINUE FOR MUCH
OF THE EXTENDED FCST.
IT IS STILL WAY TOO EARLY TO PINPOINT THE TRACK OF ISAAC AT THIS
TIME. AFOREMENTIONED UPPER LEVEL TROUGH MAY STEER SYSTEM OUT TO
SEA LATER NEXT WEEK...OR MAY BYPASS THE SYSTEM ENTIRELY. REFER TO
UPDATES FROM THE NATIONAL HURRICANE CENTER AS THE SYSTEM BEGINS
TO INCREASE IN LATITUDE.
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
SHORT TERM...LOCAL IFR/LIFR CONDS EXPECTED AT KLEB/KHIE/KAUG THIS
AM IN VALLEY FOG. VFR CONDS TO PREVAIL THIS AFTN...WITH AN ISOLD
SHRA PSBL INVOF KHIE. PATCHY FOG WILL LIKELY DEVELOP AGAIN FOR
KLEB AND KHIE THU NGT.
LONG TERM...WILL LIKELY HAVE MORNING FOG IN LEBANON AND WHITEFIELD
EACH MORNING FROM AROUND 08Z-12Z BUT OTHERWISE EXPECT VFR
CONDITIONS. THERE IS ALSO SOME POTENTIAL FOR MARINE FOG DEVELOPING
OVER THE WATERS AND DRIFTING ONSHORE AT SOME POINT DURING THE
WEEKEND.
&&
.MARINE...
SHORT TERM...WINDS AND SEA WILL REMAIN BLO SCA THRESHOLDS.
LONG TERM...A HIGH PRESSURE AXIS EXTENDING OVER THE GULF OF MAINE
THROUGH THIS WEEKEND WILL KEEP CONDITIONS TRANQUIL.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
UPDATE...HANES
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
711 PM EDT FRI AUG 24 2012
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 348 PM EDT FRI AUG 24 2012
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A GENERAL ZONAL
FLOW OVER THE NRN TIER CONUS/SRN CANADA. A SHRTWV EMBEDDED IN THIS
FLOW IS PRESENT OVER WI/UPR MI EARLY THIS AFTN AND HAS BEEN
SUPPORTING SOME ISOLD -SHRA/A FEW TS OVER MAINLY THE E HALF OF THE
CWA DESPITE PRESENCE OF DRY LLVL AIR SHOWN ON THE 12Z GRB/APX RAOBS
THAT EXTENDS WELL TO THE S AS DEPICTED ON THE 12Z RAOB FM QUAD
CITIES IOWA. OVER THE W HALF...NVA IN THE WAKE OF THE SHRTWV AND
AGGRESSIVE DRYING FOCUSED AT H5-7 WITH ENEWD SPREAD OF AIRMASS SHOWN
ON THE 12Z MPX RAOB HAS SUPPRESSED SHRA AND RESULTED IN SOME CLRG IN
DESPITE PERSISTENCE OF AXIS OF HIER H85 DEWPTS/THETA-E IN THAT AREA
PER RUC ANALYSIS. SHRTWV RDG AXIS OVER MN IS BRINGING DRY WX THERE
ALONG WITH MOCLR SKIES...BUT MORE CLDS AND SOME SHRA/TS ARE OVER THE
NRN PLAINS IN ADVANCE OF POTENT SHRTWV MOVING EWD THRU SRN ALBERTA.
LATE THIS AFTN...DESPITE NVA/AGGRESSIVE UPR DRYING IN THE WAKE OF
SLOW MOVING SHRTWV...SUSPECT SOME SHRA/TS MAY DVLP ON THE LEADING
EDGE OF THE H5-7 DRYING WHERE MORE INSOLATION WL COINCIDE WITH AREA
OF HIER H85 DEWPTS. A NUMBER OF THE RECENT HIER RES MODELS SHOW AT
LEAST ISOLD-SCT SHRA/TS DVLPG OVER THE CENTRAL ZNS...SO PAINTED AN
AXIS OF SOMEWHAT HIER CHC POPS IN THIS AREA. THE FAR W SHOULD BE DRY
UNDER MUCH DRIER H7-5 AIR AND WITH SOME MODERATION NEAR LK SUP.
LINGERING LLVL DRY AIR OVER THE E SHOULD ALSO LIMIT POPS IN THAT
AREA DESPITE MORE MID LVL MSTR THAT MIGHT SUPPORT PERSISTENT -SHRA.
TNGT...AS DEEPER SHRTWV OVER SW CANADA THIS MRNG DRIFTS EWD AND
SHRTWV OVER THE AREA SHIFTS TO THE E...ARRIVAL OF SHRTWV RDG FM MN/
ASSOCIATED H5 RISES IN CONCERT WITH LOSS OF DAYTIME HEATING SHOULD
CAUSE ANY EVNG SHRA/TS OVER MAINLY THE E AND CENTRAL ZNS TO
DISSIPATE. PCPN CHCS WL LINGER LONGEST OVER THE E CLOSER TO
DEPARTING SHRTWV/WHERE MID LVL MSTR REMAINS MOST ABUNDANT LONGEST.
ALTHOUGH THERE WAS QUITE A BIT OF FOG LAST NGT OVER MN...THE 12Z
NAM/LOCAL WRF-ARW SHOW PERSISTENT SSW LLVL FLOW DRAWING DRIER AIR
SHOWN ON THE 12Z GRB/QUAD CITY RAOBS INTO THE FA. SO EXPECT NO FOG
TO IMPACT THE CWA. DESPITE THE DRYING COLUMN...STEADY S WIND SHOULD
LIMIT THE DIURNAL TEMP FALL AT MOST SPOTS...FURTHER LIMITING THE
POTENTIAL FOR FOG.
SAT...FOCUS TURNS TO HOW QUICKLY STRONG DISTURBANCE OVER SW CANADA
THIS MRNG MIGHT INFLUENCE THE WX ESPECIALLY OVER THE WRN CWA. THE
DAY SHOULD AT LEAST START MOSUNNY WITH SHRTWV RDG AXIS/DRY H85-5
AIRMASS OVHD. BY 00Z SUN...THE SHRTWV IS PROGGED TO DRIFT NEWD TO
NEAR LK WINNIPEG AND BECOME OCCLUDED WITH H5 CUTOFF NEARLY OVER
992MB SFC LO. SINCE LLVL SLY FLOW IS FCST TO ADVECT THE DRIER
SFC-H85 AIR NOTED TO THE S OVER THE CWA THRU THE DAY AND BULK OF
DEEP LYR QVECTOR CNVGC OVER WARM CONVEYOR BELT MSTR/ATTENDANT SFC
COLD FNT ARE PROGGED TO RACH ONLY THE FAR W BY 00Z SUN...OPTED TO
SLOW DOWN EWD PUSH OF ACCOMPANYING POPS. GIVEN THE STRENGTH OF THE
SHRTWV TO THE W...PREFER THE HIER H85 FCST TEMPS BY THE NAM...WHICH
SHOWS THIS TEMP REACHING 20C OVER THE CWA VERSUS ONLY 17C BY THE
GFS. DEEP MIXING ON THE NAM FCST SDNGS YIELDS HI TEMPS REACHING ARND
90. MAX TEMPS WL BE HIEST NEAR LK SUP WHERE SLY FLOW DOWNSLOPES AND
LIMITS AND MODERATION OFF LK SUP. IN FACT...SOME RECORD HI TEMPS MAY
FALL ON SAT. AREAS DOWNWIND OF LK MI WL BE COOLEST. WITH SFC DEWPTS
LIKELY TO MIX OUT TO ARND 50 AWAY FM LK MODERATION...MIN RH WL DIP
AS LO AS 25 PCT IN THE PRESENCE OF WIND GUSTS TO 20-25 MPH ENHANCED
BY THE MIXING. FORTUNATELY...RECENT RAINS HAVE MOISTENED THE GROUND
SUFFICIENTLY TO MINIMIZE ANY FIRE WX IMPACTS.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 348 PM EDT FRI AUG 24 2012
AN UPPER-LEVEL TROUGH AND SLOW-MOVING COLD FRONT WILL CONTINUE TO
BRING RAIN AND THUNDERSTORM CHANCES TO UPPER MI THROUGH MONDAY
BEFORE DRY AND WARMER WEATHER RETURNS UNDER HIGH PRESSURE FOR THE
MIDDLE OF THE WEEK.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...A SHARP TROUGH CURRENTLY
MOVING THROUGH ALBERTA AND NORTHERN MT WILL SHIFT EAST THROUGH
SATURDAY AND INDUCE A STRONG SFC LOW OVER SOUTHERN SASKATCHEWAN. BY
SATURDAY NIGHT...THE TROUGH WILL BE LIFTING TO THE NORTHEAST THROUGH
MANITOBA WHILE BECOMING NEARLY STACKED WITH THE ASSOCIATED SFC LOW.
A COLD FRONT EXTENDING FROM A NEW OCCLUSION OVER WESTERN ONTARIO
WILL BE SURGING EASTWARD THROUGH MN SATURDAY AFTERNOON. THERE IS
VERY GOOD MODEL AGREEMENT THAT THIS COLD FRONT WILL REACH THE
WESTERN TIP OF THE CWA BY 06Z SUNDAY...THEN WASH OUT ACROSS THE
CENTRAL CWA BY SUNDAY AFTERNOON AS IT LOSES SUPPORT FROM THE
WEAKENING STACKED LOW. A SECONDARY SFC TROUGH WILL THEN CATCH UP TO
THE FRONT AND HELP KICK IT OUT OF THE CWA BY SUNDAY EVENING.
NOT TOO CONFIDENT ON WIDESPREAD PRECIP CHANCES ATTM FOR SEVERAL
REASONS. FIRST...BEST Q-VECTOR CONVERGENCE WILL EXIST NORTH CLOSER
TO THE MID-LEVEL LOW...AND SOUTH WHERE A SHORTWAVE TROUGH WILL BE
MOVING INTO THE MID-MS VALLEY FROM THE SOUTHERN PLAINS. NEXT...THE
SFC LOW FORMING IN RESPONSE TO THE SOUTHERN PLAINS TROUGH WILL
LIKELY CUTOFF A SIGNIFICANT PORTION OF THE MOISTURE SUPPLY AHEAD OF
THE FRONT. THUS...APPRECIABLE MOISTURE WILL BE CONFINED TO THE NEAR
SFC LAYER OVER UPPER MI. ANY PRECIP THAT FORMS WILL BE FORCED BY A
BAND OF H8-H7 FRONTOGENESIS ALONG THE FRONT...THOUGH MOISTURE WILL
BE LACKING IN THIS LAYER. CUT BACK POPS TO LOW CHANCE FOR MUCH OF
THE LAND...WITH HIGHER POPS OVER THE WESTERN LAKE AS IT WILL BE
CLOSER TO BETTER FORCING FROM THE LOW. SOME SFC HEATING WILL AID
DEVELOPMENT OF NEW SHOWERS AND THUNDERSTORMS IN THE AFTERNOON ACROSS
THE EAST HALF...BUT ONCE AGAIN...A LACK OF MOISTURE WILL STILL BE A
CONCERN.
INCREASED/DECREASED HIGHS IN THE WEST/EAST FOR SUNDAY TO ACCOUNT FOR
CLOUD AND PRECIP TRENDS. EXPECTATION IS THAT CLOUDS WILL QUICKLY
CLEAR WEST IN THE MORNING. H8 TEMPS WILL COOL TO AROUND 14C WITH
THIS CLEARING...BUT SHOULD STILL BE WARM ENOUGH TO PRODUCE LOW 80S
FOR HIGHS. PATCHY FOG COULD BE POSSIBLE FOR THE INTERIOR WEST SUNDAY
NIGHT...BUT DRY AIR ADVECTING INTO THE AREA SHOULD BE ENOUGH TO
SUBDUE THE THREAT.
MONDAY AND MONDAY NIGHT...AS THE MID-LEVEL LOW DRIFTS NORTHEASTWARD
TO HUDSON BAY SUNDAY NIGHT...IT WILL TAP INTO SOME ENERGY FROM THE
RAGGED POLAR VORTEX OVER NORTHERN NUNAVUT. THE REINFORCED TROUGH AND
WEAK SFC TROUGH ARE THEN PROGGED TO AFFECT THE AREA MONDAY NIGHT.
MODELS BEGIN TO DIVERGE SIGNIFICANTLY BY THIS POINT...BUT VERY
LITTLE MOISTURE ABOVE THE SFC MIXED LAYER WILL LIKELY PREVENT ANY
PRECIP. EVEN MORE...DO NOT EXPECT MUCH CLOUD COVER EXCEPT FOR
POSSIBLE AFTERNOON CUMULUS. HIGHS WILL BE IN THE 70S...WITH THE
COOLEST TEMPS NORTH CLOSER TO A H8 TEMP MIN IN NORTHERN ONTARIO.
TUESDAY THROUGH THURSDAY...A VERY IMPRESSIVE RIDGE WILL SLOWLY EDGE
INTO THE UPPER GREAT LAKES BEGINNING TUESDAY...WITH THE SFC HIGH
PRESSURE CENTERING ITSELF OVER WI/UPPER MI BY WEDNESDAY MORNING. THE
HIGH WILL CONTINUE TO GRADUALLY DRIFT SOUTHEASTWARD WEDNESDAY
THROUGH THURSDAY...WITH UPPER MI REMAINING UNDER ITS INFLUENCE.
INCREASED HIGHS THROUGH FRIDAY AS THERE WILL BE PLENTY OF SUN AND
WARM H8 TEMPS. ISENTROPIC LIFT ON THE 305-310 THEATA SFCS IN
ADDITION TO H8 MOISTURE TRANSPORT MAY RESULT IN A FEW SHOWERS AND
THUNDERSTORMS WEDNESDAY NIGHT...MAINLY NORTH.
FRIDAY...THERE IS MODEL AGREEMENT THAT THE RIDGE WILL BEGIN TO BREAK
DOWN BY EARLY FRIDAY. THE GFS IS ONCE AGAIN MORE AGGRESSIVE THAN THE
ECMWF WITH A TROUGH FROM BRITISH COLUMBIA MOVING INTO THE RIDGE. IT
IS DIFFICULT TO SAY WHICH MODEL WILL PAN OUT...IF EITHER...SO WILL
GO WITH A MODEL CONSENSUS FOR THE FORECAST.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 711 PM EDT FRI AUG 24 2012
EXPECT VFR CONDITIONS AT ALL 3 SITES THRU THIS FCST PERIOD WITH
RELATIVELY DRY LLVL AIR IN PLACE.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 348 PM EDT FRI AUG 24 2012
EXCEPT FOR A STRONGER S WIND UP TO 25 KTS OVER THE E INTO THIS
EVENING AHEAD OF AN APPROACHING LO PRES TROF...WINDS THRU THE
FORECAST PERIOD WILL BE NO HIER THAN 20 KTS AS THE COMBINATION OF A
WEAK PRES GRADIENT AND HIER OVERWATER STABILITY LIMIT WIND SPEEDS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TK
AVIATION...07
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
144 PM EDT THU AUG 23 2012
.UPDATE...
ISSUED AT 744 AM EDT THU AUG 23 2012
ALTHOUGH NOT COMPLETELY SURPRISED...THE CONVECTIVE FORECAST FOR
TODAY IS NOT PANNING OUT TOO WELL. AS THE SAYING GOES...WARM AIR
ADVECTION WAITS FOR NO ONE. THIS IS INDEED THE CASE CURRENTLY AS SCT
SHRA/TSRA ARE RAPIDLY FORMING WELL TO THE EAST OF LOW-LEVEL JET AXIS
IN AREA OF H7 MOISTURE ADVECTION /NOW INTO IRON COUNTY MICHIGAN/.
SPED UP PACE OF HIGHER POPS BRINGING THEM AS FAR EAST AS MARQUETTE
AND MENOMINEE COUNTIES THIS MORNING. DOES APPEAR THAT SHORTWAVE
ANALYZED ON RUC AND SEEN SOMEWHAT IN WV LOOP OVR NORTHEAST MN WILL
PUSH THE MORE CONCENTRATED AREA OF SHRA/TSRA OVER NORTHWEST WI
ACROSS WESTERN TIER THIS MORNING. WILL RAMP POPS UP IN THESE AREAS
AS WELL. AND LAST BUT NOT LEAST...ADDED MENTION OF FOG OVER EASTERN
CWA FOR NEXT COUPLE HOURS AS DECENT RADIATIONAL FOG DEVELOPED WHERE
WINDS ARE LIGHTEST OVER UPR MICHIGAN.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 516 AM EDT THU AUG 23 2012
THE BIG PICTURE VIEW HAS A SHORTWAVE TROUGH ORIENTED FROM
SASKATCHEWAN TO THE DAKOTAS. SHARPEST PORTION OF THE TROUGH...WITH
NOTABLE WIND SHIFT H7-H5 WAS MORE OVR CANADA VERSUS THE CONUS. JET
STREAK WAS SLIDING BY ON SOUTHERN EDGE OF THE TROUGH ACROSS WYOMING
INTO SOUTH DAKOTA. IN GENERAL A SFC TROUGH WAS LOCATED FROM
SASKATCHEWAN INTO NORTHERN NEBRASKA...BUT THERE WERE A COUPLE OF
AREAS OF LOWER PRESSURE NOTED WITHIN THE BROAD TROUGHING REGIME.
REGIONAL RADARS AND IR SATELLITE/LIGHTNING DETECTION SYSTEM SHOWED
ONE AREA OF SHRA/TSRA WAS ONGOING OVR EASTERN SOUTH DAKOTA INTO
SOUTHERN MINNESOTA ON THE NOSE OF THE HIGH PLAINS JET STREAK AND
WITHIN AREA OF STRONGER H85 TEMPERATURE ADVECTION JUST AHEAD OF MORE
CLOSED OFF SFC-H85 LOW CIRCULATION. ADDITIONAL SHRA/TSRA HAVE TAKEN
OFF SINCE 06Z JUST TO SOUTHWEST OF DLH AND ALSO INTO NORTHERN WI.
THESE SHRA/TSRA SEEM TO BE DRIVEN BY H85-H7 MOISTURE ADVECTION ON
NOSE OF 30-40 KT H85 JET NOSING INTO NORTHWEST WISCONSIN. BASED ON
RADAR TRENDS AND EXPECTED POSITION OF LOW-LEVEL JET THIS MORNING...
EXPECT PARTS OF CWA TO BE AFFECTED BY AT LEAST ISOLD SHRA/TSRA.
TREND CONTINUES THROUGH AFTERNOON WITH STRONGEST H85 CONVERGENCE AND
H85-H7 MOISTURE ADVECTION IMPACTING MAINLY WEST HALF OF CWA. KEPT
HIGHEST POPS OVER FAR WEST AND KEWEENAW...BUT SINCE THE LOW-LEVEL
JET ONLY SLIGHTLY WEAKENS AND H7 MOISTURE ADVECTION PERSISTS ATOP
STALLED OUT FRONTAL BOUNDARY OVER LAKE SUPERIOR ALONG WITH STEEP
MID-LEVEL LAPSE RATES...CANNOT COUNT OUT A SHRA/TSRA AT ANY LOCATION
OVR CWA TODAY. RISK OF SEVERE STORMS WOULD APPEAR LOW...BUT IF
CLEARING COULD OCCUR FOR A WHILE LATER THIS AFTERNOON IN THE
WEST...MLCAPES COULD PUSH TOWARD 1000 J/KG WHILE DEEP LAYER SHEAR
IMPROVES LATE TODAY /20-25 KTS/ AS SHORTWAVE TROUGH DRAWS CLOSER.
MAX TEMPERATURES KIND OF A CHALLENGE TODAY. DOES SEEM THAT IDEA OF
CONVECTIVE BLOWOFF/THICK H7-H5 MOISTURE ARE ON TRACK BASED ON LATEST
11-3.9 MICRON LOOP AND WITH CIGS UPSTREAM OF BKN100-120. BASED ON
CURRENT TEMPS IN THE 50S MOST SPOTS...AND A QUICK INCREASE OF CLOUDS
THIS MORNING...NAM OUTPUT WITH LOWER 70S MAY BE ON TO SOMETHING IN
THE WEST HALF. DID NOT GO THAT LOW OVER THE WEST JUST YET...BUT WENT
WELL BLO WHAT EVEN MIXING TO 925-900MB WOULD YIELD. BEST CHANCE FOR
WARMER TEMPS WILL BE OVER FAR NORTHERN TIER AND INTO THE EASTERN
INTERIOR AS THERE WILL BE MORE SUNSHINE THOSE AREAS INTO THE MORNING.
HIGHS BACK INTO THE 80S SEEM REASONABLE ESPECIALLY EASTERN INTERIOR.
KEYED ON LOCATION OF LOW-LEVEL JET FOR CONVECTION TONIGHT. AXIS OF
LOW-LEVEL JET IS MAINLY OVER WESTERN CWA TO START BUT THEN LIFTS
TOWARD LK SUPERIOR OVERNIGHT AS H85 LOW TRACKS NORTHEAST ACROSS
MINNESOTA INTO NORTHERN ONTARIO OVERNIGHT. MAXIMUM MOISTURE
ADVECTION H85-H7 GRADUALLY LIFTS NORTH ACROSS LK SUPERIOR AS WELL
OVERNIGHT. IN GENERAL SENSE...LARGER SCALE FORCING FOR ASCENT BETTER
TONIGHT AS SHORTWAVE AXIS WILL BE DRIFTING ACROSS WESTERN CWA. BEST
HEIGHT FALLS STAY WELL TO THE NORTH THOUGH. CONSENSUS FOR POPS
SUGGESTS GREATEST COVERAGE OVER KEWEENAW WHICH MAKES SENSE GIVEN
LOW-LEVEL JET POSITION. SIMILAR TO TODAY THOUGH...GIVEN BROAD WARM
AIR ADVECTION AND STEEP MID-LEVEL LAPSE RATES...CANNOT GO DRY
ANYWHERE TONIGHT AS THERE IS AT LEAST A SMALL CHANCE THAT SHRA/TSRA
COULD DEVELOP AT TIMES. EXPECT VERY MILD NIGHT WITH READINGS HAVING
TOUGH TIME FALLING BLO MID-UPR 60S ALONG LK SUPERIOR AND LK MICHIGAN
AND ONLY DROPPING INTO THE LOWER 60S INLAND. COULD ALSO BE BREEZY
ALONG MUCH OF LK SUPERIOR SHORE DUE TO DOWNSLOPE WARMING/MIXING WITH
THE STRONGER 950-850MB WINDS.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 516 AM EDT THU AUG 23 2012
MEDIUM RANGE MODELS DEPICT A PROGRESSIVE FLOW REGIME THRU THE LONG
TERM EVEN THOUGH PATTERN WILL AMPLIFY SOME EARLY NEXT WEEK. IT STILL
APPEARS THERE WILL BE 2 SHORTWAVES AFFECTING THE UPPER LAKES DURING
THE LONG TERM...ONE FRI AND THE SECOND DURING THE LATTER PORTION OF
THE WEEKEND. PCPN CHANCES WILL BE FOCUSED MAINLY AROUND THESE 2
SYSTEMS. PROGRESSIVE FLOW REGIME WILL LIMIT COOLING BEHIND EACH
SYSTEM...AND OVERALL...MAIN BAND OF WESTERLIES WILL BE SETTING UP N
OF THE AREA. THUS...TEMPS WILL BE ABOVE NORMAL THRU THIS FCST CYCLE.
THERE COULD BE ONE OR TWO VERY WARM/HOT DAYS AS WELL.
BEGINNING FRI...FIRST SHORTWAVE TROF WILL BE SHIFTING ACROSS THE
UPPER LAKES. WAVE WILL BE WEAKENING AS STRONGER SHORTWAVE MOVING
ACROSS SW CANADA BEGINS TO FORCE DOWNSTREAM HEIGHT RISES. SOME
CONVECTION MAY BE ONGOING FRI MORNING IN ASSOCIATION WITH 35-40KT
LOW-LEVEL JET TRANSLATING ACROSS THE AREA. WITH NOSE OF THE JET TO
THE N OF HERE...BEST PCPN POTENTIAL FRI MORNING WILL PROBABLY BE N
OF UPPER MI. MOVING INTO THE AFTN HRS...THE GFS LOOKS MUCH OVERDONE
WITH PCPN...LIKELY A RESULT OF ITS OVERLY MOIST LOW-LEVELS. FOR
EXAMPLE...IT HAS SFC DWPTS OF 65-70F INTO UPPER MI FRI...AND BY THE
WAY...YESTERDAYS 18Z GFS RUN VALID FOR 00Z LAST EVENING HAD SFC
DWPTS 10-20F TOO HIGH ACROSS PORTIONS OF THE PLAINS. THE DRIER
LOW-LEVELS ON THE NAM LOOK MUCH MORE REALISTIC GIVEN THE LARGE AREA
OF SEVERE TO EXCEPTIONAL DROUGHT UPSTREAM OVER THE CNTRL PLAINS TO
MID MISSISSIPPI VALLEY. EVEN WITH THE DRY LOW-LEVELS...NAM MLCAPE
INCREASES TO 1000-1500J/KG OVER THE W AND N FRI AFTN...PROVIDED MID
CLOUD COVER IS NOT TOO SIGNIFICANT TO LIMIT HEATING. IF CLOUDS ARE
NOT TOO WIDESPREAD...THE DRY LOW-LEVELS WILL CERTAINLY ALLOW FOR
STRONG WARMING DURING THE DAY. WITH MINIMAL CIN...THERE SHOULD BE AN
OPPORTUNITY FOR SCT CONVECTION TO DEVELOP WITH DAYTIME HEATING AS
THE WEAKENING SHORTWAVE TROF PASSES. WILL CONTINUE WITH CHC POPS. IF
LAKE BREEZE CAN MAKE A MOVE INLAND FROM LAKE SUPERIOR...AFTN
CONVECTION COVERAGE WILL BE HIGHEST ACROSS THE N. IN LEANING TOWARD
THE NAM...ALSO FAVORED ITS HIGHER MAX TEMP GUIDANCE WHICH IS MOSTLY
IN THE MID/UPPER 80S.
-SHRA/TSRA MAY LINGER INTO FRI EVENING. OTHERWISE...STRONGER
SHORTWAVE/MIDLEVEL LOW WILL BE ROLLING ACROSS SRN SASKATCHEWAN FRI
NIGHT. IN RESPONSE...LOW-LEVEL JET WILL INCREASE DOWNSTREAM INTO THE
UPPER MISSISSIPPI VALLEY. JET MAY BE FAR ENOUGH E LATE IN THE NIGHT
TO SUPPORT SOME CONVECTION OVER WRN LAKE SUPERIOR/WRN UPPER MI
OVERNIGHT.
IF ANY CONVECTION REACHES THE W LATE FRI NIGHT...IT SHOULD LIFT NE
OUT OF THE AREA SAT MORNING. SAT SHOULD THEN END UP A MOSTLY SUNNY
AND HOT DAY...ESPECIALLY FOR LATE AUG AS SHORTWAVE TRACKING THRU
SCNTRL CANADA IS STILL WELL TO THE WNW DURING THE DAY. STRONG
HEATING SHOULD OCCUR SAT AS LOW-LEVELS REMAIN DRY PER NAM FCST
SOUNDINGS. WITH THE DRY LOW LEVELS...FCST SOUNDINGS SUGGEST MIXING
HEIGHTS WILL REACH 700-750MB...WHICH YIELDS MAX TEMPS INTO THE
MID/UPPER 90S. FOR NOW...UPPER 80S/LWR 90S LOOK REASONABLE SINCE
WINDS ARE MORE SOUTHERLY RATHER THAN THE MORE IDEAL SW DIRECTION. IF
WINDS REMAIN STRONG ENOUGH TO PREVENT LAKE BREEZE OFF LAKE
SUPERIOR...DOWNSLOPE LOCATIONS NEAR THE LAKE MAY REACH THE MID 90S.
RECORD HIGH HERE AT THE OFFICE FOR SAT IS 88F. SHOULD BE ABLE TO
BREAK THAT. OBVIOUSLY...IT WILL BE COOLER TOWARD LAKE MICHIGAN WITH
SOUTHERLY WINDS.
SHORTWAVE NEAR LAKE WINNIPEG LATE SAT AFTN REACHES HUDSON BAY SUN. AS
WAS THE CASE YESTERDAY...THERE IS UNCERTAINTY IN WHETHER THAT SYSTEM
WILL PICK UP A SHORTWAVE OVER THE PLAINS. IF SO...PCPN CHANCES WILL
BE GREATLY INCREASED FOR THE UPPER LAKES SUN. RECENT MEDIUM RANGE
MODEL RUNS ARE TRENDING TOWARD THE ECMWF WHICH KEEPS THE 2 MORE
SEPARATED. AS A RESULT...NOTHING MORE THAN CHC POPS ARE WARRANTED
FOR SAT NIGHT/SUN AS MAJORTITY OF HEIGHT FALLS WITH MAIN SYSTEM PASS
WELL N OF THE FCST AREA...AND SHORTWAVE OVER THE PLAINS PASSES TOO
FAR S OF HERE TO BE MUCH OF A FACTOR.
AS ALLUDED TO ABOVE...PROGRESSIVE PATTERN WILL BEGIN TO AMPLIFY SOME
EARLY NEXT WEEK AS A MID/UPPER LEVEL RIDGE BUILDS ACROSS THE PLAINS
INTO SCNTRL CANADA. THE RIDGE WILL SHIFT E TO THE GREAT LAKES FOR
THE MIDDLE OF THE WEEK. THIS PATTERN WILL FAVOR DRY WEATHER FOR
UPPER MI DUE TO THE APPROACHING RIDGE. HOWEVER...DEVELOPING NW FLOW
MON COULD POSE SOME RISK OF ISOLD CONVECTION SINCE SUMMERTIME NW
FLOW OFTEN LENDS ITSELF TO ISOLD/SCT CONVECTION WITH ANY SUBTLE
SHORTWAVE. ALSO...SINCE FLOW REMAINS PROGRESSIVE...GFS/ECMWF SUGGEST
NEXT SHORTWAVE COULD BE APPROACHING LATE WED...PROVIDING NEXT CHC OF
PCPN. COOLEST DAYS WILL BE MON/TUE IN THE WAKE OF THE SHORTWAVE
TRACKING TO HUDSON BAY...BUT WITH SYSTEM LIFTING WELL TO THE
NE...THERE WON`T BE SIGNIFICANT CAA INTO THE UPPER LAKES...AND TEMPS
WILL LIKELY STILL REMAIN ABOVE NORMAL. SOME WARMING EXPECTED FOR
WED.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 143 PM EDT THU AUG 23 2012
VFR CONDITIONS ARE EXPECTED AT ALL SITES THROUGHOUT THE PERIOD.
POCKETS OF SHOWERS ARE ONGOING NEAR ALL SITES...WITH SOME RECENT
LIGHTNING STRIKES WITH THE CLUSTER NEAR SAW. MOST OF THIS ACTIVITY
SHOULD PASS ALL SITES DURING THE AFTERNOON. A RESURGENCE OF -SHRA
AND SOME THUNDER MAY DEVELOP LATE THIS EVENING...WITH A NORTHWARD
MOVING BAND AFFECTING CMX AND SAW...AND THEN AN EASTWARD MOVING BAND
AFFECTING IWD AND CMX. A LOW-LEVEL JET WILL CREATE WEAK LLWS AT ALL
SITES. THOUGH...WOULD NOT BE SURPRISED IF THE LLWS IS A TOUCH HIGHER
THAN WHAT IS FORECAST.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 516 AM EDT THU AUG 23 2012
EXPECT SOUTHEASTERLY WINDS UNDER 20KT TODAY. AS A LOW-LEVEL JET
DEVELOPS OVER THE AREA TONIGHT...S WINDS WILL INCREASE OVER ERN LAKE
SUPERIOR. GUSTS MAY REACH 25-30KT FROM AROUND GRAND MARAIS
NORTHWARD. AS IS TYPICALY THE CASE...THE S WINDS WILL BE LIGHTER
OVER WRN LAKE SUPERIOR. SOUTHERLY WINDS WILL DIMINISH SOME FRI...
THEN PICK UP AGAIN FRI NIGHT/SAT WITH GUSTS UP AROUND 20KT AS A LOW
PRES TROF APPROACHES FROM THE W. THE TROF WILL CROSS LAKE SUPERIOR
SUN. WINDS MON SHOULD BE UNDER 15KT AS SFC HIGH PRES BUILDS INTO THE
UPPER LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SHORT TERM...JLA
LONG TERM...ROLFSON
AVIATION...TK
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
748 AM EDT THU AUG 23 2012
.UPDATE...
ISSUED AT 744 AM EDT THU AUG 23 2012
ALTHOUGH NOT COMPLETELY SURPRISED...THE CONVECTIVE FORECAST FOR
TODAY IS NOT PANNING OUT TOO WELL. AS THE SAYING GOES...WARM AIR
ADVECTION WAITS FOR NO ONE. THIS IS INDEED THE CASE CURRENTLY AS SCT
SHRA/TSRA ARE RAPIDLY FORMING WELL TO THE EAST OF LOW-LEVEL JET AXIS
IN AREA OF H7 MOISTURE ADVECTION /NOW INTO IRON COUNTY MICHIGAN/.
SPED UP PACE OF HIGHER POPS BRINGING THEM AS FAR EAST AS MARQUETTE
AND MENOMINEE COUNTIES THIS MORNING. DOES APPEAR THAT SHORTWAVE
ANALYZED ON RUC AND SEEN SOMEWHAT IN WV LOOP OVR NORTHEAST MN WILL
PUSH THE MORE CONCENTRATED AREA OF SHRA/TSRA OVER NORTHWEST WI
ACROSS WESTERN TIER THIS MORNING. WILL RAMP POPS UP IN THESE AREAS
AS WELL. AND LAST BUT NOT LEAST...ADDED MENTION OF FOG OVER EASTERN
CWA FOR NEXT COUPLE HOURS AS DECENT RADIATIONAL FOG DEVELOPED WHERE
WINDS ARE LIGHTEST OVER UPR MICHIGAN.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 516 AM EDT THU AUG 23 2012
THE BIG PICTURE VIEW HAS A SHORTWAVE TROUGH ORIENTED FROM
SASKATCHEWAN TO THE DAKOTAS. SHARPEST PORTION OF THE TROUGH...WITH
NOTABLE WIND SHIFT H7-H5 WAS MORE OVR CANADA VERSUS THE CONUS. JET
STREAK WAS SLIDING BY ON SOUTHERN EDGE OF THE TROUGH ACROSS WYOMING
INTO SOUTH DAKOTA. IN GENERAL A SFC TROUGH WAS LOCATED FROM
SASKATCHEWAN INTO NORTHERN NEBRASKA...BUT THERE WERE A COUPLE OF
AREAS OF LOWER PRESSURE NOTED WITHIN THE BROAD TROUGHING REGIME.
REGIONAL RADARS AND IR SATELLITE/LIGHTNING DETECTION SYSTEM SHOWED
ONE AREA OF SHRA/TSRA WAS ONGOING OVR EASTERN SOUTH DAKOTA INTO
SOUTHERN MINNESOTA ON THE NOSE OF THE HIGH PLAINS JET STREAK AND
WITHIN AREA OF STRONGER H85 TEMPERATURE ADVECTION JUST AHEAD OF MORE
CLOSED OFF SFC-H85 LOW CIRCULATION. ADDITIONAL SHRA/TSRA HAVE TAKEN
OFF SINCE 06Z JUST TO SOUTHWEST OF DLH AND ALSO INTO NORTHERN WI.
THESE SHRA/TSRA SEEM TO BE DRIVEN BY H85-H7 MOISTURE ADVECTION ON
NOSE OF 30-40 KT H85 JET NOSING INTO NORTHWEST WISCONSIN. BASED ON
RADAR TRENDS AND EXPECTED POSITION OF LOW-LEVEL JET THIS MORNING...
EXPECT PARTS OF CWA TO BE AFFECTED BY AT LEAST ISOLD SHRA/TSRA.
TREND CONTINUES THROUGH AFTERNOON WITH STRONGEST H85 CONVERGENCE AND
H85-H7 MOISTURE ADVECTION IMPACTING MAINLY WEST HALF OF CWA. KEPT
HIGHEST POPS OVER FAR WEST AND KEWEENAW...BUT SINCE THE LOW-LEVEL
JET ONLY SLIGHTLY WEAKENS AND H7 MOISTURE ADVECTION PERSISTS ATOP
STALLED OUT FRONTAL BOUNDARY OVER LAKE SUPERIOR ALONG WITH STEEP
MID-LEVEL LAPSE RATES...CANNOT COUNT OUT A SHRA/TSRA AT ANY LOCATION
OVR CWA TODAY. RISK OF SEVERE STORMS WOULD APPEAR LOW...BUT IF
CLEARING COULD OCCUR FOR A WHILE LATER THIS AFTERNOON IN THE
WEST...MLCAPES COULD PUSH TOWARD 1000 J/KG WHILE DEEP LAYER SHEAR
IMPROVES LATE TODAY /20-25 KTS/ AS SHORTWAVE TROUGH DRAWS CLOSER.
MAX TEMPERATURES KIND OF A CHALLENGE TODAY. DOES SEEM THAT IDEA OF
CONVECTIVE BLOWOFF/THICK H7-H5 MOISTURE ARE ON TRACK BASED ON LATEST
11-3.9 MICRON LOOP AND WITH CIGS UPSTREAM OF BKN100-120. BASED ON
CURRENT TEMPS IN THE 50S MOST SPOTS...AND A QUICK INCREASE OF CLOUDS
THIS MORNING...NAM OUTPUT WITH LOWER 70S MAY BE ON TO SOMETHING IN
THE WEST HALF. DID NOT GO THAT LOW OVER THE WEST JUST YET...BUT WENT
WELL BLO WHAT EVEN MIXING TO 925-900MB WOULD YIELD. BEST CHANCE FOR
WARMER TEMPS WILL BE OVER FAR NORTHERN TIER AND INTO THE EASTERN
INTERIOR AS THERE WILL BE MORE SUNSHINE THOSE AREAS INTO THE MORNING.
HIGHS BACK INTO THE 80S SEEM REASONABLE ESPECIALLY EASTERN INTERIOR.
KEYED ON LOCATION OF LOW-LEVEL JET FOR CONVECTION TONIGHT. AXIS OF
LOW-LEVEL JET IS MAINLY OVER WESTERN CWA TO START BUT THEN LIFTS
TOWARD LK SUPERIOR OVERNIGHT AS H85 LOW TRACKS NORTHEAST ACROSS
MINNESOTA INTO NORTHERN ONTARIO OVERNIGHT. MAXIMUM MOISTURE
ADVECTION H85-H7 GRADUALLY LIFTS NORTH ACROSS LK SUPERIOR AS WELL
OVERNIGHT. IN GENERAL SENSE...LARGER SCALE FORCING FOR ASCENT BETTER
TONIGHT AS SHORTWAVE AXIS WILL BE DRIFTING ACROSS WESTERN CWA. BEST
HEIGHT FALLS STAY WELL TO THE NORTH THOUGH. CONSENSUS FOR POPS
SUGGESTS GREATEST COVERAGE OVER KEWEENAW WHICH MAKES SENSE GIVEN
LOW-LEVEL JET POSITION. SIMILAR TO TODAY THOUGH...GIVEN BROAD WARM
AIR ADVECTION AND STEEP MID-LEVEL LAPSE RATES...CANNOT GO DRY
ANYWHERE TONIGHT AS THERE IS AT LEAST A SMALL CHANCE THAT SHRA/TSRA
COULD DEVELOP AT TIMES. EXPECT VERY MILD NIGHT WITH READINGS HAVING
TOUGH TIME FALLING BLO MID-UPR 60S ALONG LK SUPERIOR AND LK MICHIGAN
AND ONLY DROPPING INTO THE LOWER 60S INLAND. COULD ALSO BE BREEZY
ALONG MUCH OF LK SUPERIOR SHORE DUE TO DOWNSLOPE WARMING/MIXING WITH
THE STRONGER 950-850MB WINDS.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 516 AM EDT THU AUG 23 2012
MEDIUM RANGE MODELS DEPICT A PROGRESSIVE FLOW REGIME THRU THE LONG
TERM EVEN THOUGH PATTERN WILL AMPLIFY SOME EARLY NEXT WEEK. IT STILL
APPEARS THERE WILL BE 2 SHORTWAVES AFFECTING THE UPPER LAKES DURING
THE LONG TERM...ONE FRI AND THE SECOND DURING THE LATTER PORTION OF
THE WEEKEND. PCPN CHANCES WILL BE FOCUSED MAINLY AROUND THESE 2
SYSTEMS. PROGRESSIVE FLOW REGIME WILL LIMIT COOLING BEHIND EACH
SYSTEM...AND OVERALL...MAIN BAND OF WESTERLIES WILL BE SETTING UP N
OF THE AREA. THUS...TEMPS WILL BE ABOVE NORMAL THRU THIS FCST CYCLE.
THERE COULD BE ONE OR TWO VERY WARM/HOT DAYS AS WELL.
BEGINNING FRI...FIRST SHORTWAVE TROF WILL BE SHIFTING ACROSS THE
UPPER LAKES. WAVE WILL BE WEAKENING AS STRONGER SHORTWAVE MOVING
ACROSS SW CANADA BEGINS TO FORCE DOWNSTREAM HEIGHT RISES. SOME
CONVECTION MAY BE ONGOING FRI MORNING IN ASSOCIATION WITH 35-40KT
LOW-LEVEL JET TRANSLATING ACROSS THE AREA. WITH NOSE OF THE JET TO
THE N OF HERE...BEST PCPN POTENTIAL FRI MORNING WILL PROBABLY BE N
OF UPPER MI. MOVING INTO THE AFTN HRS...THE GFS LOOKS MUCH OVERDONE
WITH PCPN...LIKELY A RESULT OF ITS OVERLY MOIST LOW-LEVELS. FOR
EXAMPLE...IT HAS SFC DWPTS OF 65-70F INTO UPPER MI FRI...AND BY THE
WAY...YESTERDAYS 18Z GFS RUN VALID FOR 00Z LAST EVENING HAD SFC
DWPTS 10-20F TOO HIGH ACROSS PORTIONS OF THE PLAINS. THE DRIER
LOW-LEVELS ON THE NAM LOOK MUCH MORE REALISTIC GIVEN THE LARGE AREA
OF SEVERE TO EXCEPTIONAL DROUGHT UPSTREAM OVER THE CNTRL PLAINS TO
MID MISSISSIPPI VALLEY. EVEN WITH THE DRY LOW-LEVELS...NAM MLCAPE
INCREASES TO 1000-1500J/KG OVER THE W AND N FRI AFTN...PROVIDED MID
CLOUD COVER IS NOT TOO SIGNIFICANT TO LIMIT HEATING. IF CLOUDS ARE
NOT TOO WIDESPREAD...THE DRY LOW-LEVELS WILL CERTAINLY ALLOW FOR
STRONG WARMING DURING THE DAY. WITH MINIMAL CIN...THERE SHOULD BE AN
OPPORTUNITY FOR SCT CONVECTION TO DEVELOP WITH DAYTIME HEATING AS
THE WEAKENING SHORTWAVE TROF PASSES. WILL CONTINUE WITH CHC POPS. IF
LAKE BREEZE CAN MAKE A MOVE INLAND FROM LAKE SUPERIOR...AFTN
CONVECTION COVERAGE WILL BE HIGHEST ACROSS THE N. IN LEANING TOWARD
THE NAM...ALSO FAVORED ITS HIGHER MAX TEMP GUIDANCE WHICH IS MOSTLY
IN THE MID/UPPER 80S.
-SHRA/TSRA MAY LINGER INTO FRI EVENING. OTHERWISE...STRONGER
SHORTWAVE/MIDLEVEL LOW WILL BE ROLLING ACROSS SRN SASKATCHEWAN FRI
NIGHT. IN RESPONSE...LOW-LEVEL JET WILL INCREASE DOWNSTREAM INTO THE
UPPER MISSISSIPPI VALLEY. JET MAY BE FAR ENOUGH E LATE IN THE NIGHT
TO SUPPORT SOME CONVECTION OVER WRN LAKE SUPERIOR/WRN UPPER MI
OVERNIGHT.
IF ANY CONVECTION REACHES THE W LATE FRI NIGHT...IT SHOULD LIFT NE
OUT OF THE AREA SAT MORNING. SAT SHOULD THEN END UP A MOSTLY SUNNY
AND HOT DAY...ESPECIALLY FOR LATE AUG AS SHORTWAVE TRACKING THRU
SCNTRL CANADA IS STILL WELL TO THE WNW DURING THE DAY. STRONG
HEATING SHOULD OCCUR SAT AS LOW-LEVELS REMAIN DRY PER NAM FCST
SOUNDINGS. WITH THE DRY LOW LEVELS...FCST SOUNDINGS SUGGEST MIXING
HEIGHTS WILL REACH 700-750MB...WHICH YIELDS MAX TEMPS INTO THE
MID/UPPER 90S. FOR NOW...UPPER 80S/LWR 90S LOOK REASONABLE SINCE
WINDS ARE MORE SOUTHERLY RATHER THAN THE MORE IDEAL SW DIRECTION. IF
WINDS REMAIN STRONG ENOUGH TO PREVENT LAKE BREEZE OFF LAKE
SUPERIOR...DOWNSLOPE LOCATIONS NEAR THE LAKE MAY REACH THE MID 90S.
RECORD HIGH HERE AT THE OFFICE FOR SAT IS 88F. SHOULD BE ABLE TO
BREAK THAT. OBVIOUSLY...IT WILL BE COOLER TOWARD LAKE MICHIGAN WITH
SOUTHERLY WINDS.
SHORTWAVE NEAR LAKE WINNIPEG LATE SAT AFTN REACHES HUDSON BAY SUN. AS
WAS THE CASE YESTERDAY...THERE IS UNCERTAINTY IN WHETHER THAT SYSTEM
WILL PICK UP A SHORTWAVE OVER THE PLAINS. IF SO...PCPN CHANCES WILL
BE GREATLY INCREASED FOR THE UPPER LAKES SUN. RECENT MEDIUM RANGE
MODEL RUNS ARE TRENDING TOWARD THE ECMWF WHICH KEEPS THE 2 MORE
SEPARATED. AS A RESULT...NOTHING MORE THAN CHC POPS ARE WARRANTED
FOR SAT NIGHT/SUN AS MAJORTITY OF HEIGHT FALLS WITH MAIN SYSTEM PASS
WELL N OF THE FCST AREA...AND SHORTWAVE OVER THE PLAINS PASSES TOO
FAR S OF HERE TO BE MUCH OF A FACTOR.
AS ALLUDED TO ABOVE...PROGRESSIVE PATTERN WILL BEGIN TO AMPLIFY SOME
EARLY NEXT WEEK AS A MID/UPPER LEVEL RIDGE BUILDS ACROSS THE PLAINS
INTO SCNTRL CANADA. THE RIDGE WILL SHIFT E TO THE GREAT LAKES FOR
THE MIDDLE OF THE WEEK. THIS PATTERN WILL FAVOR DRY WEATHER FOR
UPPER MI DUE TO THE APPROACHING RIDGE. HOWEVER...DEVELOPING NW FLOW
MON COULD POSE SOME RISK OF ISOLD CONVECTION SINCE SUMMERTIME NW
FLOW OFTEN LENDS ITSELF TO ISOLD/SCT CONVECTION WITH ANY SUBTLE
SHORTWAVE. ALSO...SINCE FLOW REMAINS PROGRESSIVE...GFS/ECMWF SUGGEST
NEXT SHORTWAVE COULD BE APPROACHING LATE WED...PROVIDING NEXT CHC OF
PCPN. COOLEST DAYS WILL BE MON/TUE IN THE WAKE OF THE SHORTWAVE
TRACKING TO HUDSON BAY...BUT WITH SYSTEM LIFTING WELL TO THE
NE...THERE WON`T BE SIGNIFICANT CAA INTO THE UPPER LAKES...AND TEMPS
WILL LIKELY STILL REMAIN ABOVE NORMAL. SOME WARMING EXPECTED FOR
WED.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 745 AM EDT THU AUG 23 2012
SHRA/TSRA HAVE EXPANDED THIS MORNING JUST WEST OF UPR MICHIGAN AND
THESE WILL AFFECT ALL TAF SITES THROUGH AT LEAST EARLY AFTN. FOR MOST
PART EXPECT VFR CONDITIONS THOUGH THERE COULD BE BRIEF SUB VFR VSBY
IN THE HEAVIER SHRA/TSRA OVER WESTERN UPR MICHIGAN THIS MORNING. LULL
MAY FORM LATER TODAY BEFORE MORE SHRA/TSRA DEVELOP AGAIN TONIGHT.
BEST CHANCE FOR TSRA TONIGHT WILL BE AT IWD AND CMX. HAVE INCLUDED A
MENTION OF VICINITY THUNDER /VCTS/ IN THOSE TAFS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 516 AM EDT THU AUG 23 2012
EXPECT SOUTHEASTERLY WINDS UNDER 20KT TODAY. AS A LOW-LEVEL JET
DEVELOPS OVER THE AREA TONIGHT...S WINDS WILL INCREASE OVER ERN LAKE
SUPERIOR. GUSTS MAY REACH 25-30KT FROM AROUND GRAND MARAIS
NORTHWARD. AS IS TYPICALY THE CASE...THE S WINDS WILL BE LIGHTER
OVER WRN LAKE SUPERIOR. SOUTHERLY WINDS WILL DIMINISH SOME FRI...
THEN PICK UP AGAIN FRI NIGHT/SAT WITH GUSTS UP AROUND 20KT AS A LOW
PRES TROF APPROACHES FROM THE W. THE TROF WILL CROSS LAKE SUPERIOR
SUN. WINDS MON SHOULD BE UNDER 15KT AS SFC HIGH PRES BUILDS INTO THE
UPPER LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SHORT TERM...JLA
LONG TERM...ROLFSON
AVIATION...JLA
MARINE...ROLFSON
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1235 PM CDT THU AUG 23 2012
.AVIATION...08/23/18Z ISSUANCE...
VFR...WITH PATCHES OF IFR IN FOG LATE TONIGHT. A MID DECK WITH
SCATTERED HIGH BASE THUNDERSTORMS WILL CONTINUE FROM THE IRON
RANGE EAST AND ACROSS NORTHWEST WISCONSIN. IN THE MOIST AND
UNSTABLE AIR MASS...IT IS POSSIBLE FOR ISOLATED THUNDERSTORMS TO
DEVELOP TONIGHT. A POST-FRONTAL OFFSHORE FLOW WILL RESULTE IN VFR
WITH SCATTERED CLOUDS FRIDAY.
&&
.PREV DISCUSSION... /ISSUED 1023 AM CDT THU AUG 23 2012/
UPDATE...GIVEN UNCERTAINTY IN FORCING MECHANISMS AND INCREASINGLY
UNSTABLE NATURE OF ATMOSPHERE...TOUGH TO CHANGE MUCH IN EXISTING
FCST. INITIAL SHORTWAVE TROF HAS MOVED INTO ERN CWA. THIS HAS
DRAGGED MAIN PWS PLUME FROM PINE COUNTY TO WRN BAYFIELD COUNTY.
INCREASED POPS OVER NWRN WISC THIS MORNING AS LATEST 88D SHOWS NEW
DEVELOPMENT OVER SRN PINE/BURNETT COUNTIES. RUC13 ANALYSIS SHOWS
FAIRLY WELL DEFINED WIND SHEAR AXIS FROM ARROWHEAD WEST TOWARDS NE
NODAK. NEW CELLS HAVE DEVELOPED OVER RANGE AND ARROWHEAD AND HAVE
RAISED POPS FOR THIS AREA TODAY. GENERAL IDEA IS THAT FIRST
SHORTWAVE WILL ADVECT EAST OF CWA BY AFTN. A DECREASE IN POPS OVER
SERN WISC ZONES WITH BETTER INSTABILITY TAXIS REALIGNING FROM BRD
LAKES VICINITY NORTHEAST INTO ARROWHEAD/RANGE. LOWERED MAX TEMPS A
FEW DEGREES OVER NWRN WISC DUE TO CLOUD COVER/PRECIP.
PREV DISCUSSION... /ISSUED 337 AM CDT THU AUG 23 2012/
SHORT TERM...LATEST NOAM WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL
SHORTWAVE CURRENTLY OVER MN AND WRN WI. SCTD SHOWERS AND STORMS
HAVE DEVELOPED IN A BAND ACROSS OUR SRN ZONES EARLY THIS
MORNING...GENERALLY AFFECTING AREAS SOUTH OF THE TWIN PORTS
INCLUDING THE SAINT CROIX RIVER VALLEY. THIS ACTIVITY WILL
CONTINUE TO SPREAD NWD ACROSS THE REST OF OUR CWA TODAY...WITH
SOME REDEVELOPMENT ALSO EXPECTED FARTHER SOUTH AND WEST. HOWEVER
DUE TO DISAGREEMENTS BETWEEN THE NWP MODELS...HAVE KEPT POPS IN
THE HIGH CHANCE RANGE WITH MENTION OF SCTD SHOWERS AND STORMS.
PRECIP CHANCES WILL INCREASE TO LIKELY TONIGHT AS TROUGH AXIS
MOVES OVER THE NORTHLAND AND THE CONVECTION BECOMES MORE
ORGANIZED...MAINLY ALONG AND EAST OF A LINE FROM ELY TO CLOQUET TO
PINE CITY MN. THE SHOWERS AND STORMS WILL GRADUALLY MOVE OFF TO
THE EAST OVERNIGHT TONIGHT AND DIMINISH ACROSS OUR ERN ZONES
DURING THE DAY ON FRIDAY.
THE NAM12 CONTINUES TO SHOW MODERATE INSTABILITY DEVELOPING THIS
AFTERNOON AND EVENING IN ASSOC WITH THIS DISTURBANCE...ALTHOUGH
DAYTIME HEATING WILL BE A KEY FACTOR IF CLOUD COVER BECOMES MORE
WIDESPREAD. WITH MUCAPES RANGING FROM 1500-3000 J/KG AND WITH WEAK
TO MODERATE SHEAR POSSIBLE...ISOLD STRONG/SEVERE STORMS ARE
POSSIBLE AS OUTLINED IN SWODY1 ISSUED BY THE SPC. CONDITIONS WILL
BE WARM AND HUMID ON FRIDAY WITH HIGHS IN THE MID 80S AS SKIES
CLEAR OUT ALLOWING FOR APPRECIABLE DAYTIME HEATING.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY.
AN UPPER LEVEL LOW WILL MOVE TOWARD SOUTHEAST SASKATCHEWAN BY 12Z
SAT...THEN CONTINUE EAST THEN NORTHEAST AND MOVE INTO NORTHERN
ONTARIO BY 12Z SUNDAY. ALTHOUGH THE STRONGEST FORCING REMAINS WELL
NORTH...A FRONTAL BOUNDARY WILL SLOWLY MOVE THROUGH THE CWA
SATURDAY THROUGH SUNDAY. WE HAVE A SMALL CHANCE FOR SHOWERS/STORMS
FRIDAY NIGHT WITH PERSISTENT WEAK WARM AIR/MOISTURE ADVECTION
ACROSS THE CWA. THE FRONT WILL MOVE SLOWLY THROUGH THE CWA
SATURDAY INTO SUNDAY AND WE HAVE HIGHER POPS DUE TO STRONGER
FORCING WITH THE FRONT.
MODELS IN DECENT AGREEMENT BUILDING HIGH PRESSURE INTO THE REGION
MONDAY WITH A DRY DAY EXPECTED.
THE ECMWF IS A BIT OF AN OUTLIER TUESDAY MOVING IT`S UPPER RIDGE
FURTHER EAST OVER MINNESOTA WITH LOW PRESSURE ON IT`S HEELS...WHILE
THE GEM AND GFS KEEP HIGH PRESSURE ALOFT CENTERED OVER CO...WITH
RIDGING EXTENDING NORTH. THE ECMWF HAS BEEN CONSISTENT OVER IT`S
PAST FEW RUNS...AND THE GFS 12Z 22ND RUN WAS CLOSER TO THE CURRENT
ECMWF...BOTH THE 18Z AND 00Z GFS RUNS ARE IN LINE WITH THE LATEST
GEM. THE RESULT OF THE DIFFERENCES WOULD BE BRINGING IN PRECIP
FASTER IF WE FOLLOWED THE ECMWF. HOWEVER...WE WILL GO WITH
PERSISTENCE AND THE GEM/GFS AND CONTINUE A DRY FORECAST INTO TUESDAY
NIGHT...BEFORE ADDING POPS WEDNESDAY.
HIGHS THROUGH THE PERIOD WILL GENERALLY RANGE FROM THE MID SEVENTIES
TO LOWER EIGHTIES.
&&
.POINT TEMPS/POPS...
DLH 78 62 83 65 / 50 60 10 20
INL 81 59 83 62 / 50 40 10 50
BRD 82 63 86 68 / 50 50 10 30
HYR 81 64 86 64 / 60 60 30 20
ASX 80 64 84 64 / 50 60 30 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...CANNON
LONG TERM....EOM
AVIATION...EOM
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1023 AM CDT THU AUG 23 2012
.UPDATE...GIVEN UNCERTAINTY IN FORCING MECHANISMS AND INCREASINGLY
UNSTABLE NATURE OF ATMOSPHERE...TOUGH TO CHANGE MUCH IN EXISTING
FCST. INITIAL SHORTWAVE TROF HAS MOVED INTO ERN CWA. THIS HAS
DRAGGED MAIN PWS PLUME FROM PINE COUNTY TO WRN BAYFIELD COUNTY.
INCREASED POPS OVER NWRN WISC THIS MORNING AS LATEST 88D SHOWS NEW
DEVELOPMENT OVER SRN PINE/BURNETT COUNTIES. RUC13 ANALYSIS SHOWS
FAIRLY WELL DEFINED WIND SHEAR AXIS FROM ARROWHEAD WEST TOWARDS NE
NODAK. NEW CELLS HAVE DEVELOPED OVER RANGE AND ARROWHEAD AND HAVE
RAISED POPS FOR THIS AREA TODAY. GENERAL IDEA IS THAT FIRST
SHORTWAVE WILL ADVECT EAST OF CWA BY AFTN. A DECREASE IN POPS OVER
SERN WISC ZONES WITH BETTER INSTABILITY TAXIS REALIGNING FROM BRD
LAKES VICINITY NORTHEAST INTO ARROWHEAD/RANGE. LOWERED MAX TEMPS A
FEW DEGREES OVER NWRN WISC DUE TO CLOUD COVER/PRECIP.
&&
.PREV DISCUSSION... /ISSUED 635 AM CDT THU AUG 23 2012/
AVIATION...12Z TAFS
WAA AIDING IN SHOWER AND THUNDERSTORM DEVELOPMENT THIS MORNING. WE
INCLUDED THEM IN THE KDLH/KHYR/KHIB TAFS THROUGH 15Z OR 16Z...AND
KBRD THROUGH 14Z. WE PUT A BREAK IN THE TAFS...THEN PUT
THUNDERSTORMS BACK IN A FRONT/TROUGH MOVES INTO THE NORTHLAND
LATER THIS AFTERNOON AND EVENING. MVFR CONDITIONS WILL BE POSSIBLE
TODAY AND THIS EVENING IN THE STRONGER STORMS. FOG WILL BE
POSSIBLE TONIGHT AS THE STORMS SHIFT EAST...AND SKIES CLEAR AND
WINDS ARE EXPECTED TO BE LIGHT.
PREV DISCUSSION... /ISSUED 337 AM CDT THU AUG 23 2012/
SHORT TERM...LATEST NOAM WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL
SHORTWAVE CURRENTLY OVER MN AND WRN WI. SCTD SHOWERS AND STORMS
HAVE DEVELOPED IN A BAND ACROSS OUR SRN ZONES EARLY THIS
MORNING...GENERALLY AFFECTING AREAS SOUTH OF THE TWIN PORTS
INCLUDING THE SAINT CROIX RIVER VALLEY. THIS ACTIVITY WILL
CONTINUE TO SPREAD NWD ACROSS THE REST OF OUR CWA TODAY...WITH
SOME REDEVELOPMENT ALSO EXPECTED FARTHER SOUTH AND WEST. HOWEVER
DUE TO DISAGREEMENTS BETWEEN THE NWP MODELS...HAVE KEPT POPS IN
THE HIGH CHANCE RANGE WITH MENTION OF SCTD SHOWERS AND STORMS.
PRECIP CHANCES WILL INCREASE TO LIKELY TONIGHT AS TROUGH AXIS
MOVES OVER THE NORTHLAND AND THE CONVECTION BECOMES MORE
ORGANIZED...MAINLY ALONG AND EAST OF A LINE FROM ELY TO CLOQUET TO
PINE CITY MN. THE SHOWERS AND STORMS WILL GRADUALLY MOVE OFF TO
THE EAST OVERNIGHT TONIGHT AND DIMINISH ACROSS OUR ERN ZONES
DURING THE DAY ON FRIDAY.
THE NAM12 CONTINUES TO SHOW MODERATE INSTABILITY DEVELOPING THIS
AFTERNOON AND EVENING IN ASSOC WITH THIS DISTURBANCE...ALTHOUGH
DAYTIME HEATING WILL BE A KEY FACTOR IF CLOUD COVER BECOMES MORE
WIDESPREAD. WITH MUCAPES RANGING FROM 1500-3000 J/KG AND WITH WEAK
TO MODERATE SHEAR POSSIBLE...ISOLD STRONG/SEVERE STORMS ARE
POSSIBLE AS OUTLINED IN SWODY1 ISSUED BY THE SPC. CONDITIONS WILL
BE WARM AND HUMID ON FRIDAY WITH HIGHS IN THE MID 80S AS SKIES
CLEAR OUT ALLOWING FOR APPRECIABLE DAYTIME HEATING.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY.
AN UPPER LEVEL LOW WILL MOVE TOWARD SOUTHEAST SASKATCHEWAN BY 12Z
SAT...THEN CONTINUE EAST THEN NORTHEAST AND MOVE INTO NORTHERN
ONTARIO BY 12Z SUNDAY. ALTHOUGH THE STRONGEST FORCING REMAINS WELL
NORTH...A FRONTAL BOUNDARY WILL SLOWLY MOVE THROUGH THE CWA
SATURDAY THROUGH SUNDAY. WE HAVE A SMALL CHANCE FOR SHOWERS/STORMS
FRIDAY NIGHT WITH PERSISTENT WEAK WARM AIR/MOISTURE ADVECTION
ACROSS THE CWA. THE FRONT WILL MOVE SLOWLY THROUGH THE CWA
SATURDAY INTO SUNDAY AND WE HAVE HIGHER POPS DUE TO STRONGER
FORCING WITH THE FRONT.
MODELS IN DECENT AGREEMENT BUILDING HIGH PRESSURE INTO THE REGION
MONDAY WITH A DRY DAY EXPECTED.
THE ECMWF IS A BIT OF AN OUTLIER TUESDAY MOVING IT`S UPPER RIDGE
FURTHER EAST OVER MINNESOTA WITH LOW PRESSURE ON IT`S HEELS...WHILE
THE GEM AND GFS KEEP HIGH PRESSURE ALOFT CENTERED OVER CO...WITH
RIDGING EXTENDING NORTH. THE ECMWF HAS BEEN CONSISTENT OVER IT`S
PAST FEW RUNS...AND THE GFS 12Z 22ND RUN WAS CLOSER TO THE CURRENT
ECMWF...BOTH THE 18Z AND 00Z GFS RUNS ARE IN LINE WITH THE LATEST
GEM. THE RESULT OF THE DIFFERENCES WOULD BE BRINGING IN PRECIP
FASTER IF WE FOLLOWED THE ECMWF. HOWEVER...WE WILL GO WITH
PERSISTENCE AND THE GEM/GFS AND CONTINUE A DRY FORECAST INTO TUESDAY
NIGHT...BEFORE ADDING POPS WEDNESDAY.
HIGHS THROUGH THE PERIOD WILL GENERALLY RANGE FROM THE MID SEVENTIES
TO LOWER EIGHTIES.
&&
.POINT TEMPS/POPS...
DLH 78 62 83 65 / 50 60 10 20
INL 81 59 83 62 / 50 40 10 50
BRD 82 63 86 68 / 50 50 10 30
HYR 81 64 86 64 / 60 60 30 20
ASX 80 64 84 64 / 50 60 30 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...CANNON
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1233 AM CDT THU AUG 23 2012
.AVIATION...
THE LOW LEVEL JET WILL CONTINUE THROUGH 09Z...WITH SOUNDINGS
INDICATING WINDS JUST ABOVE THE SURFACE OF 30KTS. LOW LEVEL WIND
SHEAR IS NOT EXPECTED AT THIS TIME. SCATTERED TO BROKEN CLOUD COVER
IS EXPECTED THROUGH THE PERIOD...HOWEVER CEILINGS WILL REMAIN VFR.
MODELS INDICATE A PERIOD OF -SHRA FOR KLBF BETWEEN 12Z-18Z WITH A
WEAK MID LEVEL DISTURBANCE. ALTHOUGH NOT IN KLBF TAF...A FEW BRIEF
LIGHT SHOWERS POSSIBLE BETWEEN 06Z AND 12Z. NO MENTION FOR KVTN
HOWEVER AS TIME SECTIONS SHOWED DRIER WITH INSUFFICIENT LIFT. WINDS
FOR THURSDAY TO GENERALLY BE LIGHT EAST TO NORTHEAST AOB 10KT.
&&
.PREV DISCUSSION... /ISSUED 629 PM CDT WED AUG 22 2012/
DISCUSSION...
NO OBVIOUS FOR ISOLATED STORM DEVELOPMENT SHOWING ON RADAR OR VSBY
SATELLITE. WATER VAPOR AND THE RAP MODEL INDICATE A MID LEVEL DISTURBANCE
NEAR KSLC. THIS DISTURBANCE IS PROGGED BY ALL MODELS TO BEGIN
AFFECTING THE FCST AREA THURSDAY AFTERNOON SO RAIN CHANCES THIS
EVENING...ALBEIT ISOLATED...LOOK UNCERTAIN AT THIS TIME. NOTE THAT
THE RAP IS POOLING CONSIDERABLE MOISTURE ACROSS SWRN LATE TONIGHT.
THE COULD RAISE THE PROSPECT OF STRATUS BUT NON IS INDICATED BY 12Z
AT KMCK.
THUS THE FCST TURNS TO THURSDAY AFTERNOON. THE NAM AND GEM BRING
A WEAK COLD FRONT THROUGH THE FCST AREA OVERNIGHT. NEITHER THE GFS
NOR THE ECM SHOW THIS FEATURE. THEY INSTEAD WASH THE FRONT OUT
NEAR THE SOUTH DAKOTA BORDER AND MAINTAIN A BELT OF STRONG
SOUTHWEST WINDS FARTHER WEST DURING THE DAY THURSDAY. BY THIS TIME
THE DISTURBANCE CURRENTLY ACROSS NRN UT SHOULD BE OPERATING ACROSS
KS AND SRN NEB. ALL MODELS SUGGEST A HEAVY RAIN CENTER WILL
DEVELOP THURSDAY NIGHT THROUGH FRIDAY...SOMEWHERE ACROSS KS. THE
NAM WAS THE FARTHEST NORTH PRODUCING 1.8 INCHES NEAR NORTON KS.
THE 12Z GFS INDICATED 11 INCHES OVER KHLC. THE ECM AROUND 2.5 NEAR
KP28 AND THE SREF HAD 1.35 NEAR KGLD. ALL OF THESE SOLNS WERE
BLENDED TOGETHER TO PRODUCE CHC POPS ACROSS SWRN AND SCNTL NEB. BY
FRIDAY MORNING MOST SOLNS SHOW A CLOSE 500 MB LOW FORMING OVER KS
AND IT APPEARS THE MODELS ARE TAKING PIECES OF THE DEEP SWRN U.S.
UPPER LEVEL LOW ACROSS THE ROCKIES AND RECONSOLIDATING IT OVER
KS.
SO THE FCST FOLLOWS THESE SOLNS AND PARTS OF THE FCST AREA WILL BE
ON THE PERIPHERY OF WHAT COULD BECOME A LARGE COMPLEX OF SHOWERS
AND THUNDERSTORMS LATE THURSDAY THROUGH FRIDAY. A POWERFUL NRN
STREAM DISTURBANCE WILL TRACK ALONG THE CANADIAN BORDER FRIDAY
NIGHT AND SATURDAY AND THIS SHOULD OPEN UP THE CLOSED KS LOW AND
SHEAR IT OUT TO THE EAST SOMETIME DURING THE DAY SATURDAY.. A
SIGNIFICANT COLD FRONT WILL SWEEP SOUTH THROUGH THE FCST AREA
SATURDAY PRODUCING HIGHS IN THE 80S WITH DRY CONDITIONS.
SUNDAY THROUGH WEDNESDAY...DRY WEATHER IS EXPECTED. THE DROUGHT
RIDGE WILL GRADUALLY BUILD NORTH TOWARD THE CNTL PLAINS AND
ANOTHER STRONG NORTHERN STREAM LOW WILL BEGIN TRACKING ALONG THE
CANADIAN BORDER. THIS SHOULD SPAWN A HIGH PLAINS LOW PRESSURE
SYSTEM AND DRAW WARM AIR BACK NORTH. TEMPS SHOULD RISE BACK INTO
THE LOW TO MID 90S NEXT WEEK. A COLD FRONT SHOULD MOVE THROUGH
LATE TUESDAY OR WEDNESDAY FOR COOLER HIGHS WEDNESDAY .
TEMPERATURES THURSDAY AND FRIDAY ARE A COMPLEX BLEND OF BIAS
CORRECTED MODEL DATA AND GUIDANCE. THE MODELS ARE FCSTING DEEP
MOISTURE AND STRATUS FRIDAY AND SATURDAY MORNINGS WHICH COULD HAVE
A BIG IMPACT ON HIGH TEMPERATURES.
FIRE WEATHER...
AS FUELS REMAIN VERY DRY...CONDITIONS THROUGH THE REMAINDER OF THIS
AFTERNOON WILL BE CRITICAL OR NEAR CRITICAL ACROSS MUCH OF WESTERN
AND NORTH CENTRAL NEBRASKA WITH RELATIVE HUMIDITY NEAR 20 PERCENT
AND GUSTY WINDS. FOR FIRE ZONE 209...A RED FLAG WARNING WILL
CONTINUE THROUGH 8 PM CDT.
WINDS WILL STAY BREEZY AND CONTINUE TO GUST TO 25 MPH OR HIGHER THIS
EVENING DUE TO A TIGHT PRESSURE GRADIENT AND STRONG WINDS ALOFT
MIXING DOWN TO THE SURFACE. THESE WINDS WILL DIMINISH SLIGHTLY INTO
THURSDAY MORNING...WITH GUSTS ON THURSDAY EXPECTED TO BE LESSER
ACROSS THE DISTRICTS. IN TERMS OF HUMIDITY...COOLING TEMPERATURES
THIS EVENING WILL CAUSE THE AIR TO BECOME MORE HUMID...WHICH WILL
ALLEVIATE THE DISTRICTS FROM THE CRITICAL FIRE WEATHER CONDITIONS.
IN ADDITION...THERE IS POTENTIAL FOR THUNDERSTORMS ALONG AND WEST OF
A LINE FROM OGALLALA TO THEDFORD TO AINSWORTH THIS EVENING. ANY
THUNDERSTORMS WILL HAVE THREATS ERRATIC AND GUSTY WINDS AND DRY
LIGHTNING...AS THE BOUNDARY LAYER IS VERY DRY. BELIEVE ANY STORMS
WILL BE ISOLATED IN NATURE.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...NWS
AVIATION...CLB
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1043 PM EDT FRI AUG 24 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE SLOWLY UP THE CAROLINA COAST OVERNIGHT.
HIGH PRESSURE WILL BUILD SOUTH THIS WEEKEND...BRINGING SLIGHTLY
DRIER AIR INTO THE REGION. TROPICAL STORM ISAAC IS EXPECTED TO
MOVE INTO THE EASTERN GULF OF MEXICO EARLY NEXT WEEK. REMNANTS
OF ISAAC COULD BRING UNSETTLED WEATHER TO THE CAROLINAS BY THE
MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 10:30 PM FRIDAY...ISOLATED SHOWERS CONTINUE WELL INLAND AND
JUST OFFSHORE...WHICH APPEAR TO BE SPINNING AROUND THE PERIPHERY
OF AN UPPER LOW. THESE SHOULD GRADUALLY FADE AS DRYER AIR WORKS IN
OVERNIGHT. PREVIOUS DISCUSSIONS FOLLOW:
LOOKS LIKE WE HAVE FINALLY BROKEN OUR STREAK OF CONSECUTIVE DAYS
AT 70F OR ABOVE...DATING BACK TO JUNE 28TH. THIS WAS A RECORD
STRING OF 56 DAYS. THE PREVIOUS RECORD WAS SET IN 1941 WITH 52
CONSECUTIVE DAYS.
MID TO UPPER LOW WILL TRACK UP THE SOUTHEAST COAST THROUGH
TONIGHT. THE H5 CIRCULATION REMAINS BROAD WITH CENTER TIGHTENING A
BIT OVERNIGHT WITH CENTER FORECAST OVER NC/VA BORDER BY SAT
MORNING. THE ASSOCIATED SURFACE LOW JUST E-SE OF CAPE FEAR THIS
AFTERNOON WILL MOVE NORTH AND BECOME MORE ELONGATED AS IT WEAKENS
THROUGH TONIGHT. NAM STILL SHOWING BEST ENERGY ASSOCIATED WITH
THIS LOW TO MOVE FROM COASTAL WATERS JUST SOUTH OF CAPE FEAR DUE
NORTH INTO NC THIS AFTERNOON. HRRR MODEL SHOWING BEST CHC FOR
HEAVIER PCP FROM THE TIP OF CAPE FEAR NORTH ALONG THE NORTH
CAROLINA COAST MAINLY FROM NEW HANOVER COUNTY THROUGH PENDER
COUNTY. THE BEST CHC OF HEAVIER PCP WILL OCCUR DURING THIS TIME
BUT BULLSEYE FOR HEAVIEST RAIN IN TSTMS WILL REMAIN OVER THE
WATERS TO THE EAST. THE GREATEST THREAT THROUGH WILL BE POTENTIAL
FOR FLOODING AS STEERING FLOW OVER MOST LAND AREAS WILL REMAIN
VERY WEAK. PCP WATER VALUES WILL REMAIN AROUND 2 INCHES UP THE
CAPE FEAR COAST DROPPING OFF AS YOU MOVE INLAND DOWN LESS THAN AN
INCH IN DRIER AIR AND SUBSIDENCE ON BACK END OF LOW WEST OF LOCAL
CWA...OVER CENTRAL TO WESTERN CAROLINAS. WILL KEEP LOW END POPS
INLAND AS SOME ENERGY ROTATES AROUND THE LOW...BUT OVERALL CLOUDS
AND COOLER NORTHERLY FLOW KEEPING TEMPS JUST AROUND 80 AND OVERALL
MORE STABLE ATMOSPHERE.
MODEL SOUNDINGS AND MOISTURE PROFILES SHOWING DRIER AIR WORKING
ITS WAY IN ON THE BACK EDGE OF LOW THROUGH THE MID TO UPPER
LEVELS TONIGHT AS IT LIFTS OFF TO THE NORTH. THIS WILL HELP PCP
SHUT OFF OVER LOCAL AREA. NAM SHOWS PCP WATER VALUES DROPPING
DOWN LESS THAN 1.5 INCHES BY SAT MORNING. CLOUDS...PCP AND FOG
WILL HELP KEEP TEMPS IN THE MID 60S AND CLOSER TO 70 WHERE GREATER
DEWPOINT AIR WILL HANG ON THE LATEST. MAY SEE STRATUS DEVELOP AS
MOISTURE BECOMES TRAPPED UNDER LOW LEVEL INVERSION...MORE PROBABLE
CLOSER TO THE COAST.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 340 PM FRIDAY...A DRIER PATTERN ANTICIPATED THIS WEEKEND...AS
DRY MID-LEVEL AIR OVERSPREADS THE REGION...AND A SURFACE LOW PULLS
SLUGGISHLY NORTH AND AWAY FROM OUR AREA. WEAK UPPER LOW POSITIONED
JUST NORTH OF OUR AREA SATURDAY AND SUNDAY WILL CONTINUE TO FEED
DRY AIR ALOFT...BUT CONCURRENTLY SHOULD PROMPT PLENTY OF DIURNAL
BUT MOSTLY CAPPED CUMULUS. CONVERGENCE OFFSHORE LATE IN THE PERIOD
MAY BRING COASTAL SHOWERS SUNDAY NIGHT. WHILE A SHOWER CANNOT BE
RULED OUT ON THE SEA BREEZE FRONT THIS WEEKEND...ACTIVITY SHOULD
IN OR BELOW THE ISOLATED CATEGORY.
MAXIMUM TEMPS WITH PARTIAL CLOUDS AND HIGH PRESSURE WEDGED IN FROM
THE NORTH...SHOULD RESULT IN MAINLY MIDDLE AND UPPER 80S BOTH DAYS.
MINIMUM TEMPS WILL DIP BELOW 70 MOST LOCATIONS BY DAYBREAK SAT/SUN
BUT QUITE A BIT MORE MILD AT THE COAST IN ONSHORE WIND DIRECTION.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 340 PM FRIDAY...SENSIBLE WEATHER THROUGH THE EXTENDED WILL
DEPEND ALMOST ENTIRELY ON ISAAC AND HIS POTENTIAL IMPACTS TO THE
REGION. STILL CONSIDERABLE UNCERTAINTY DUE TO TRACK
FORECASTS...WHICH...UNFORTUNATELY...WILL CREATE SIGNIFICANT
DIFFERENCES IN THE WEATHER ACROSS THE ILM CWA.
GFS/CMC ARE IN DECENT AGREEMENT WITH THEIR OVERALL EVOLUTION OF
ISAAC WHEN COMPARED TO THE ECMWF WHICH IS THE OUTLIER OF THE THREE
MODELS. WHILE THE ECMWF SLOWLY BRINGS ISAAC UP THROUGH THE GULF
COAST AND MEANDERS IT NW INTO THE TN VLY THROUGH MIDWEEK BEFORE
DISSIPATING...THE GFS/CMC BRING IT SLIGHTLY FURTHER EAST INTO THE
PANHANDLE OF FLORIDA ON TUESDAY AND THEN MAKE A SHARP
RECURVE...MOVING ISAAC`S REMNANTS BASICALLY OVER THE ILM CWA ON
WEDNESDAY. WILL LEAN TOWARDS THE GFS/CMC CONSENSUS...THE THINKING
THAT THE LARGE RIDGE WHICH FORCES THE ECMWF SOLUTION TO REMAIN WEST
IS OVERDONE. THIS MEANS DEEP S/SE FLOW MON/TUE WHICH SHOULD SUPPORT
ADVECTION SHOWERS...ESPECIALLY NEAR THE COAST...AND THEN A MUCH
WETTER DAY WEDNESDAY AS MID LEVEL THETA-E RIDGE ASSOCIATED WITH
ISAAC AND ITS REMNANTS...MOVES OVERHEAD. BY THURSDAY WE SHOULD BE ON
THE DRY WEST SUBSIDENT SIDE OF THE STORM AND WILL DRY OUT FOR LATE
WEEK. STILL MUCH UNCERTAINTY...BUT WILL RAMP POP UPWARDS THROUGH
WEDNESDAY BEFORE RAPIDLY TAILING OFF ON THURSDAY/FRIDAY.
NOTE THAT CURRENT FORECAST IS AT LEAST SLIGHTLY DIFFERENT THAN
HPC/NHC WHICH IS FAVORING A MUCH MORE WESTERN AND SLOWER
TRACK...ECMWF...FOR ISAAC. IF THE ECMWF TRACK WERE TO
VERIFY...WEDNESDAY WOULD STILL BE THE WETTEST DAY...SO POP TRENDS
WOULD STILL BE CORRECT...BUT OVERALL LESS RAINFALL ALONG WITH SLOWER
DECREASE IN POP WOULD BE NEEDED IN THAT SOLUTION (I.E. BETTER RAIN
CHANCES CONTINUING THROUGH THE END OF THE WEEK). WILL HAVE TO
MONITOR GUIDANCE TRENDS AND MODIFY FURTHER FORECAST UPDATES AS
NEEDED.
TEMPS WILL BE AROUND CLIMO MOST DAYS...WARMING TO ABOVE BY THE END
OF THE WEEK.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
AS OF 00Z...WET PATTERN FINALLY IS BREAKING AS A FAIRLY STRONG VORT
PULLS NORTHEAST...TAKING THE FRONT WITH IT. THE MODERATE TO HEAVY
PRECIP ALONG THE COAST TODAY WILL LIKELY CONTRIBUTE TO IFR
CONDITIONS AT THE COASTAL TERMINALS SOMETIME AFTER MIDNIGHT. THE
INLAND TERMINALS ARE A BIT MORE UNCERTAIN. THERE IS NOT AS MUCH LOW
LEVEL MOISTURE...BUT RADIATIONAL COOLING CONDITIONS ARE REASONABLY
GOOD...AND THE TMP/DPT SPREAD IS NOT MUCH TO BEGIN WITH. LIKEWISE A
LIGHT NORTHEAST WIND IS FAVORABLE. WILL STICK WITH MVFR AT THIS TIME
BUT WILL MONITOR CLOSELY. SATURDAY...A GREAT DAY TO BE OUTSIDE WITH
MODERATE TEMPERATURES AND A NOTICEABLY DRIER ATMOSPHERE. CONTINUED LIGHT
NORTHEAST FLOW...WITH VFR CONDITIONS EXPECTED BY 15Z...CONTINUING
THROUGH THE END OF THE FORECAST PERIOD.
EXTENDED OUTLOOK...ISOLATED SHRA/TSRA MON. BETTER CHANCE OF SHOWERS
AND STORMS TUESDAY AND WEDNESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 10:30 PM FRIDAY...LATEST OBS SHOW WINDS ARE SETTLING INTO A
NORTHWESTERLY FLOW...WITH WINDS NOW IN THE 10 TO 15 KT
RANGE...HIGHEST NORTH. SEAS RANGE FROM 2 TO 4 FT. NO CHANGES TO
THE GOING FORECAST...PREVIOUS DISCUSSION FOLLOWS:
SFC WINDS OF AROUND 15 KTS WILL DIMINISH A BIT OVERNIGHT AS THEY
BACK TOWARD THE NW. THIS OFF-SHORE FLOW WILL ACT TO LOWER SEAS BUT
A LONGER PERIOD E-SE SWELL UP TO 16 SECONDS WILL COUNTERACT THIS
OFF SHORE FLOW AND WILL PRODUCE A SLIGHT INCREASE IN OVERALL SEAS
OVERNIGHT. SEAS WILL BUILD TO 3 TO 4 FT MAINLY ACROSS THE OUTER
WATERS. EXPECT ROUGHER SEAS WITH HIGHER WINDS AND SEAS IN TSTMS
THROUGH THIS EVENING AND ALSO REDUCED VSBYS DUE TO HEAVY RAIN.
RADAR CONTINUED TO SHOW THE POSSIBILITY OF WATERSPOUTS IN STORMS
OVER THE OUTER COASTAL WATERS THIS AFTERNOON.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 340 PM
FRIDAY...OUTSIDE OF TSTMS WINDS WILL REMAIN MANAGEABLE SATURDAY
AND SUNDAY...AS A SURFACE LOW OVER THE WATERS MOVES SLOWLY NORTH
OF THE AREA. WINDS WILL VEER EAST SUNDAY AS HIGH PRESSURE
CONSOLIDATES OVER NEW ENGLAND. THE COMBINATION OF WIND- WAVES AND
SWELL WAVES WILL KEEP SEAS MAINLY 3-4 FEET THIS WEEKEND AND UP TO
5 FEET AT TIMES WELL OFFSHORE. NUMEROUS SHOWERS AND TSTMS WILL
BECOME SCATTERED TO ISOLATED THIS WEEKEND...AS THE SFC LOW PULLS
NORTH OF SURF CITY BY DAYBREAK SATURDAY...AND DRY AIR ALOFT HELPS
TO SQUELCH STORM DEVELOPMENT.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 340 PM FRIDAY...QUITE A BIT OF UNCERTAINTY THROUGH THE
EXTENDED AS WIND/WAVE CONDITIONS COULD VARY CONSIDERABLY DEPENDING
ON WHAT HAPPENS WITH TS ISAAC. ANTICIPATE E/SE WINDS MON THROUGH TUE
AS ISAAC MOVES ALONG THE WEST COAST OF FLORIDA AND INTO THE GULF
COAST REGION. THE CONTINUED E/SE WINDS AROUND 10 KTS...UP TO 15 KTS
ACROSS THE SOUTHERN WATERS...WILL GENERATE 2-4 FT SOUTHERLY WIND
WAVES. THESE WIND WAVES WILL COMBINE WITH WHAT SHOULD BE INCREASING
S/SE SWELL OF 4-5FT/9SEC DUE TO TROPICAL SYSTEMS ISAAC AND JOYCE.
GUIDANCE IS NOT VERY ROBUST IN DEVELOPING ANY SIGNIFICANT VERY LONG
PERIOD SWELL...BUT NEVERTHELESS...3-5 FT SEAS ARE EXPECTED THROUGH
TUESDAY...WITH 6 FOOTERS POSSIBLE ACROSS THE SOUTHERN WATERS. SEAS
COULD BUILD MUCH HIGHER WEDNESDAY...ESPECIALLY IF GFS/CMC ARE
CORRECT...DUE TO INCREASING SOUTHERLY WINDS...AND SMALL CRAFT
ADVISORY CONDITIONS WILL BE POSSIBLE AT THE END OF THE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...REK/RGZ
SHORT TERM...MJC
LONG TERM...JDW
AVIATION...DL
MARINE...MJC/REK/JDW/RGZ
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
802 PM EDT FRI AUG 24 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE SLOWLY UP THE CAROLINA COAST OVERNIGHT.
HIGH PRESSURE WILL BUILD SOUTH THIS WEEKEND...BRINGING SLIGHTLY
DRIER AIR INTO THE REGION. TROPICAL STORM ISAAC IS EXPECTED TO
MOVE INTO THE EASTERN GULF OF MEXICO EARLY NEXT WEEK. REMNANTS
OF ISAAC COULD BRING UNSETTLED WEATHER TO THE CAROLINAS BY THE
MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 7:30 PM FRIDAY...SUBSTANTIAL WIDE-SPREAD PRECIPITATION HAS
ENDED FOR THE EVENING...WITH MAIN RAIN SHIELD HAVING NOW PUSHED
NORTHEAST OF THE FORECAST AREA. A BROKEN BAND OF LIGHT RAINSHOWERS
IS NOW PUSHING WEST ACROSS THE CWA...HOWEVER THIS ACTIVITY IS VERY
LIGHT AND WILL NOT AMOUNT TO MORE THAN A FEW HUNDREDTHS OF AN INCH IN
ANY ONE LOCATION. HAVE UPDATED POPS ACCORDINGLY.
LOOKS LIKE WE HAVE FINALLY BROKEN OUR STREAK OF CONSECUTIVE DAYS
AT 70F OR ABOVE...DATING BACK TO JUNE 28TH. THIS WAS A RECORD
STRING OF 56 DAYS. THE PREVIOUS RECORD WAS SET IN 1941 WITH 52
CONSECUTIVE DAYS.
PREVIOUS DISCUSSION FOLLOWS:
MID TO UPPER LOW WILL TRACK UP THE SOUTHEAST COAST THROUGH
TONIGHT. THE H5 CIRCULATION REMAINS BROAD WITH CENTER TIGHTENING A
BIT OVERNIGHT WITH CENTER FORECAST OVER NC/VA BORDER BY SAT
MORNING. THE ASSOCIATED SURFACE LOW JUST E-SE OF CAPE FEAR THIS
AFTERNOON WILL MOVE NORTH AND BECOME MORE ELONGATED AS IT WEAKENS
THROUGH TONIGHT. NAM STILL SHOWING BEST ENERGY ASSOCIATED WITH
THIS LOW TO MOVE FROM COASTAL WATERS JUST SOUTH OF CAPE FEAR DUE
NORTH INTO NC THIS AFTERNOON. HRRR MODEL SHOWING BEST CHC FOR
HEAVIER PCP FROM THE TIP OF CAPE FEAR NORTH ALONG THE NORTH
CAROLINA COAST MAINLY FROM NEW HANOVER COUNTY THROUGH PENDER
COUNTY. THE BEST CHC OF HEAVIER PCP WILL OCCUR DURING THIS TIME
BUT BULLSEYE FOR HEAVIEST RAIN IN TSTMS WILL REMAIN OVER THE
WATERS TO THE EAST. THE GREATEST THREAT THROUGH WILL BE POTENTIAL
FOR FLOODING AS STEERING FLOW OVER MOST LAND AREAS WILL REMAIN
VERY WEAK. PCP WATER VALUES WILL REMAIN AROUND 2 INCHES UP THE
CAPE FEAR COAST DROPPING OFF AS YOU MOVE INLAND DOWN LESS THAN AN
INCH IN DRIER AIR AND SUBSIDENCE ON BACK END OF LOW WEST OF LOCAL
CWA...OVER CENTRAL TO WESTERN CAROLINAS. WILL KEEP LOW END POPS
INLAND AS SOME ENERGY ROTATES AROUND THE LOW...BUT OVERALL CLOUDS
AND COOLER NORTHERLY FLOW KEEPING TEMPS JUST AROUND 80 AND OVERALL
MORE STABLE ATMOSPHERE.
MODEL SOUNDINGS AND MOISTURE PROFILES SHOWING DRIER AIR WORKING
ITS WAY IN ON THE BACK EDGE OF LOW THROUGH THE MID TO UPPER
LEVELS TONIGHT AS IT LIFTS OFF TO THE NORTH. THIS WILL HELP PCP
SHUT OFF OVER LOCAL AREA. NAM SHOWS PCP WATER VALUES DROPPING
DOWN LESS THAN 1.5 INCHES BY SAT MORNING. CLOUDS...PCP AND FOG
WILL HELP KEEP TEMPS IN THE MID 60S AND CLOSER TO 70 WHERE GREATER
DEWPOINT AIR WILL HANG ON THE LATEST. MAY SEE STRATUS DEVELOP AS
MOISTURE BECOMES TRAPPED UNDER LOW LEVEL INVERSION...MORE PROBABLE
CLOSER TO THE COAST.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 340 PM FRIDAY...A DRIER PATTERN ANTICIPATED THIS WEEKEND...AS
DRY MID-LEVEL AIR OVERSPREADS THE REGION...AND A SURFACE LOW PULLS
SLUGGISHLY NORTH AND AWAY FROM OUR AREA. WEAK UPPER LOW POSITIONED
JUST NORTH OF OUR AREA SATURDAY AND SUNDAY WILL CONTINUE TO FEED
DRY AIR ALOFT...BUT CONCURRENTLY SHOULD PROMPT PLENTY OF DIURNAL
BUT MOSTLY CAPPED CUMULUS. CONVERGENCE OFFSHORE LATE IN THE PERIOD
MAY BRING COASTAL SHOWERS SUNDAY NIGHT. WHILE A SHOWER CANNOT BE
RULED OUT ON THE SEA BREEZE FRONT THIS WEEKEND...ACTIVITY SHOULD
IN OR BELOW THE ISOLATED CATEGORY.
MAXIMUM TEMPS WITH PARTIAL CLOUDS AND HIGH PRESSURE WEDGED IN FROM
THE NORTH...SHOULD RESULT IN MAINLY MIDDLE AND UPPER 80S BOTH DAYS.
MINIMUM TEMPS WILL DIP BELOW 70 MOST LOCATIONS BY DAYBREAK SAT/SUN
BUT QUITE A BIT MORE MILD AT THE COAST IN ONSHORE WIND DIRECTION.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 340 PM FRIDAY...SENSIBLE WEATHER THROUGH THE EXTENDED WILL
DEPEND ALMOST ENTIRELY ON ISAAC AND HIS POTENTIAL IMPACTS TO THE
REGION. STILL CONSIDERABLE UNCERTAINTY DUE TO TRACK
FORECASTS...WHICH...UNFORTUNATELY...WILL CREATE SIGNIFICANT
DIFFERENCES IN THE WEATHER ACROSS THE ILM CWA.
GFS/CMC ARE IN DECENT AGREEMENT WITH THEIR OVERALL EVOLUTION OF
ISAAC WHEN COMPARED TO THE ECMWF WHICH IS THE OUTLIER OF THE THREE
MODELS. WHILE THE ECMWF SLOWLY BRINGS ISAAC UP THROUGH THE GULF
COAST AND MEANDERS IT NW INTO THE TN VLY THROUGH MIDWEEK BEFORE
DISSIPATING...THE GFS/CMC BRING IT SLIGHTLY FURTHER EAST INTO THE
PANHANDLE OF FLORIDA ON TUESDAY AND THEN MAKE A SHARP
RECURVE...MOVING ISAAC`S REMNANTS BASICALLY OVER THE ILM CWA ON
WEDNESDAY. WILL LEAN TOWARDS THE GFS/CMC CONSENSUS...THE THINKING
THAT THE LARGE RIDGE WHICH FORCES THE ECMWF SOLUTION TO REMAIN WEST
IS OVERDONE. THIS MEANS DEEP S/SE FLOW MON/TUE WHICH SHOULD SUPPORT
ADVECTION SHOWERS...ESPECIALLY NEAR THE COAST...AND THEN A MUCH
WETTER DAY WEDNESDAY AS MID LEVEL THETA-E RIDGE ASSOCIATED WITH
ISAAC AND ITS REMNANTS...MOVES OVERHEAD. BY THURSDAY WE SHOULD BE ON
THE DRY WEST SUBSIDENT SIDE OF THE STORM AND WILL DRY OUT FOR LATE
WEEK. STILL MUCH UNCERTAINTY...BUT WILL RAMP POP UPWARDS THROUGH
WEDNESDAY BEFORE RAPIDLY TAILING OFF ON THURSDAY/FRIDAY.
NOTE THAT CURRENT FORECAST IS AT LEAST SLIGHTLY DIFFERENT THAN
HPC/NHC WHICH IS FAVORING A MUCH MORE WESTERN AND SLOWER
TRACK...ECMWF...FOR ISAAC. IF THE ECMWF TRACK WERE TO
VERIFY...WEDNESDAY WOULD STILL BE THE WETTEST DAY...SO POP TRENDS
WOULD STILL BE CORRECT...BUT OVERALL LESS RAINFALL ALONG WITH SLOWER
DECREASE IN POP WOULD BE NEEDED IN THAT SOLUTION (I.E. BETTER RAIN
CHANCES CONTINUING THROUGH THE END OF THE WEEK). WILL HAVE TO
MONITOR GUIDANCE TRENDS AND MODIFY FURTHER FORECAST UPDATES AS
NEEDED.
TEMPS WILL BE AROUND CLIMO MOST DAYS...WARMING TO ABOVE BY THE END
OF THE WEEK.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 00Z...WET PATTERN FINALLY IS BREAKING AS A FAIRLY STRONG VORT
PULLS NORTHEAST...TAKING THE FRONT WITH IT. THE MODERATE TO HEAVY
PRECIP ALONG THE COAST TODAY WILL LIKELY CONTRIBUTE TO IFR
CONDITIONS AT THE COASTAL TERMINALS SOMETIME AFTER MIDNIGHT. THE
INLAND TERMINALS ARE A BIT MORE UNCERTAIN. THERE IS NOT AS MUCH LOW
LEVEL MOISTURE...BUT RADIATIONAL COOLING CONDITIONS ARE REASONABLY
GOOD...AND THE TMP/DPT SPREAD IS NOT MUCH TO BEGIN WITH. LIKEWISE A
LIGHT NORTHEAST WIND IS FAVORABLE. WILL STICK WITH MVFR AT THIS TIME
BUT WILL MONITOR CLOSELY. SATURDAY...A GREAT DAY TO BE OUTSIDE WITH
MODERATE TEMPERATURES AND A NOTICEABLY DRIER ATMOSPHERE. CONTINUED LIGHT
NORTHEAST FLOW...WITH VFR CONDITIONS EXPECTED BY 15Z...CONTINUING
THROUGH THE END OF THE FORECAST PERIOD.
EXTENDED OUTLOOK...ISOLATED SHRA/TSRA MON. BETTER CHANCE OF SHOWERS
AND STORMS TUESDAY AND WEDNESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 7:30 PM FRIDAY...LATEST OBS SHOW A GENERALLY NORTHERLY FLOW
WITH WINDS IN THE 10 TO 20 KT RANGE...HIGHEST NORTH. SEAS RANGE
FROM 1 TO 3 FT. NO CHANGES TO THE GOING FORECAST...PREVIOUS
DISCUSSION FOLLOWS:
SFC WINDS OF AROUND 15 KTS WILL DIMINISH A BIT OVERNIGHT AS THEY
BACK TOWARD THE NW. THIS OFF-SHORE FLOW WILL ACT TO LOWER SEAS BUT
A LONGER PERIOD E-SE SWELL UP TO 16 SECONDS WILL COUNTERACT THIS
OFF SHORE FLOW AND WILL PRODUCE A SLIGHT INCREASE IN OVERALL SEAS
OVERNIGHT. SEAS WILL BUILD TO 3 TO 4 FT MAINLY ACROSS THE OUTER
WATERS. EXPECT ROUGHER SEAS WITH HIGHER WINDS AND SEAS IN TSTMS
THROUGH THIS EVENING AND ALSO REDUCED VSBYS DUE TO HEAVY RAIN.
RADAR CONTINUED TO SHOW THE POSSIBILITY OF WATERSPOUTS IN STORMS
OVER THE OUTER COASTAL WATERS THIS AFTERNOON.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 340 PM
FRIDAY...OUTSIDE OF TSTMS WINDS WILL REMAIN MANAGEABLE SATURDAY
AND SUNDAY...AS A SURFACE LOW OVER THE WATERS MOVES SLOWLY NORTH
OF THE AREA. WINDS WILL VEER EAST SUNDAY AS HIGH PRESSURE
CONSOLIDATES OVER NEW ENGLAND. THE COMBINATION OF WIND- WAVES AND
SWELL WAVES WILL KEEP SEAS MAINLY 3-4 FEET THIS WEEKEND AND UP TO
5 FEET AT TIMES WELL OFFSHORE. NUMEROUS SHOWERS AND TSTMS WILL
BECOME SCATTERED TO ISOLATED THIS WEEKEND...AS THE SFC LOW PULLS
NORTH OF SURF CITY BY DAYBREAK SATURDAY...AND DRY AIR ALOFT HELPS
TO SQUELCH STORM DEVELOPMENT.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 340 PM FRIDAY...QUITE A BIT OF UNCERTAINTY THROUGH THE
EXTENDED AS WIND/WAVE CONDITIONS COULD VARY CONSIDERABLY DEPENDING
ON WHAT HAPPENS WITH TS ISAAC. ANTICIPATE E/SE WINDS MON THROUGH TUE
AS ISAAC MOVES ALONG THE WEST COAST OF FLORIDA AND INTO THE GULF
COAST REGION. THE CONTINUED E/SE WINDS AROUND 10 KTS...UP TO 15 KTS
ACROSS THE SOUTHERN WATERS...WILL GENERATE 2-4 FT SOUTHERLY WIND
WAVES. THESE WIND WAVES WILL COMBINE WITH WHAT SHOULD BE INCREASING
S/SE SWELL OF 4-5FT/9SEC DUE TO TROPICAL SYSTEMS ISAAC AND JOYCE.
GUIDANCE IS NOT VERY ROBUST IN DEVELOPING ANY SIGNIFICANT VERY LONG
PERIOD SWELL...BUT NEVERTHELESS...3-5 FT SEAS ARE EXPECTED THROUGH
TUESDAY...WITH 6 FOOTERS POSSIBLE ACROSS THE SOUTHERN WATERS. SEAS
COULD BUILD MUCH HIGHER WEDNESDAY...ESPECIALLY IF GFS/CMC ARE
CORRECT...DUE TO INCREASING SOUTHERLY WINDS...AND SMALL CRAFT
ADVISORY CONDITIONS WILL BE POSSIBLE AT THE END OF THE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...REK/RGZ
SHORT TERM...MJC
LONG TERM...JDW
AVIATION...DL
MARINE...MJC/REK/JDW/RGZ
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
119 PM EDT THU AUG 23 2012
.SYNOPSIS...
UPPER LEVEL DISTURBANCES AND A STALLED FRONT OFFSHORE WILL KEEP THE
WEATHER UNSETTLED THROUGH FRIDAY. SOME SLIGHTLY DRIER AIR WILL WORK
INTO THE AREA OVER THE WEEKEND. EARLY NEXT WEEK...ALL EYES WILL BE
FOCUSED ON TROPICAL CYCLONE ISAAC TO OUR SOUTH AND ITS EVENTUAL
TRACK. THE RISK FOR WET WEATHER WILL RETURN DURING TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 PM THURSDAY...I HAVE INCREASED POPS TO "LIKELY" FOR THE
REMAINDER OF THE AFTERNOON ALONG THE COAST FROM JUST SOUTH OF
WILMINGTON THROUGH THE GRAND STRAND...AND ALSO JUST NORTH OF
FLORENCE WHERE A CONCENTRATED BATCH OF SHOWERS RECENTLY HAS
DEVELOPED. OBVIOUSLY A FEW FOLKS UNDER THESE SLOW-MOVING SHOWERS ARE
GOING TO PICK UP SEVERAL INCHES OF RAIN...BUT BROADER SCALE AREAL
AVERAGES SHOULD BE AROUND HALF AN INCH. SYNOPTIC REASONING AS
EXPLAINED EARLIER IN UNCHANGED. PREVIOUS DISCUSSION FROM 10 AM
FOLLOWS...
THE FRONT IS EASILY DISCERNIBLE ON MORNING
VISIBLE SATELLITE IMAGERY AND EXTENDS FROM ABOUT 15 MILES EAST OF
GEORGETOWN TO 10 MILES NORTH OF THE FRYING PAN SHOALS TOWER TO ABOUT
70 MILES EAST OF WRIGHTSVILLE BEACH. THE LIGHT NE FLOW COVERING THE
EASTERN CAROLINAS IS NOT A SIGNIFICANTLY DIFFERENT AIRMASS THAN THAT
FOUND SOUTH OF THE FRONT...AND SHOULD DO NOTHING TO PREVENT SHOWERS
AND EMBEDDED THUNDERSTORMS FROM DEVELOPING LATER TODAY.
A STREAM OF HIGH PRECIPITABLE WATER VALUES EXTENDS FROM THE EASTERN
GULF OF MEXICO NORTHEAST ALONG THE CAROLINA COAST. BLENDED TOTAL
PRECIPITABLE WATER IMAGERY FROM SATELLITE AGREES WITH MODEL ANALYSES
SHOWING 1.80 TO 2.00 INCH PRECIPITABLE WATER OVERHEAD. MID-LEVEL
TEMPERATURES FROM THE 12Z CHS AND MHX SOUNDINGS WERE SURPRISINGLY
COOL...-9 C AT 500 MB...AND LAPSE RATES WERE SLIGHTLY STEEPER THAN
MOIST-ADIABATIC UP THROUGH 300 MB...ALL INDICATIVE OF AN AIRMASS
THAT IS SUITABLE FOR CONVECTION. IT WILL ONLY TAKE TEMPERATURES
REACHING THE LOWER 80S TO IGNITE ANOTHER ROUND OF SCATTERED SHOWERS
AND EMBEDDED THUNDERSTORMS.
THE LATEST THREE HRRR RUNS INDICATE THAT MUCH LIKE YESTERDAY WE CAN
EXPECT THE GREATEST CONCENTRATION OF CONVECTION WITHIN 30-40 MILES
OF THE COAST THIS AFTERNOON. COMPUTED CELL MOTION FROM THE 12Z
SOUNDINGS IS LESS THAN 5 KNOTS...AND BOUNDARY INTERACTIONS WILL MOST
LIKELY OVERWHELM THAT DRIFT AND CREATE VARIABLE AND ERRATIC
EFFECTIVE STORM MOTION. WITH SUCH HIGH PRECIPITABLE WATER VALUES WE
EXPECT LOCALLY HEAVY RAIN TO OCCUR WITH MINOR FLOODING POSSIBLE.
HIGHS SHOULD REACH THE LOWER 80S WITH PERHAPS A FEW MID 80S POSSIBLE
OUT WEST OF FLORENCE.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...MID LEVEL LOW OR REALLY A WEAKNESS WILL
SLOWLY LIFT OUT TO THE NORTHEAST AS A WEAK RIDGE BUILDS ACROSS THE
TENNESSEE VALLEY. HIGH PRESSURE WILL BUILD IN FROM THE NORTHEAST
WITH THE AXIS TO THE WEST ALONG THE APPALACHIANS. THE GFS HAS TRENDED
A LITTLE WETTER AND POPS ARE INCLUDED FOR BOTH FRIDAY AND TO A
LESSER EXTENT SATURDAY. CONTINUED THE RECENT TREND OF GOING ABOVE
THE WARMEST GUIDANCE FOR TEMPERATURES.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 3 AM THURSDAY...FORECAST AREA WILL BE IN A VERY NARROW
WEAKNESS OF MID LEVEL TROUGHING INITIALLY. THIS AREA WILL SLOWLY
DEEPEN AS A SHORTWAVE RIDES ACROSS THE GREAT LAKES AND EVENTUALLY THE
NORTHEAST. THIS WEAKNESS WILL BE THE KEY TO THE EVENTUAL FORECAST OF
ISAAC. AT THE SURFACE...HIGH PRESSURE WILL PREVAIL UNTIL LATE IN THE
PERIOD WHEN CLOUDS AND RAIN INCREASE FROM WHAT REMAINS OF ISAAC. THE
TREND HAS BEEN TO INCREASE CLOUDS AND POPS FOR LATE IN THE PERIOD
WITH THE USUAL DISCLAIMER THAT THE TRACK COULD CHANGE AND AT THIS
POINT THE EMPHASIS WITH THE CLOUDS AND RAIN ARE WITH THE REMNANTS OF
THE SYSTEM. OTHERWISE...SUNDAY SHOULD REMAIN DRY WITH ONLY SLIGHT
CHANCE POPS FOR MONDAY VIA THE SEA BREEZE. NO CHANGES TO THE
TEMPERATURE FORECAST WHICH HOVERS AROUND CLIMATOLOGY FOR HIGHS AND
SLIGHTLY BELOW AT LEAST INITIALLY FOR THE LOWS. THE AFOREMENTIONED
INCREASE IN MOISTURE NARROWS THE DIURNAL RANGE LATE IN THE PERIOD.
&&
.AVIATION /18Z THURSDAY THROUGH MONDAY/...
AS OF 18Z...AREAS OF MVFR THIS WILL GRADUALLY IMPROVE TO VFR.
MVFR/IFR ANTICIPATED LATE OVERNIGHT INTO THE EARLY MORNING HOURS
DUE TO SHOWERS...STRATUS...AND FOG. OTHERWISE EXPECT VFR.
THOUGH PATCHES OF VFR ARE WITHIN THE AREA...MVFR RESTRICTIONS WILL
CONTINUE ACROSS PORTIONS OF THE AREA AS LOW STRATUS LINGERS AND
ISOLATED SHOWERS DEVELOP. INTO THE AFTERNOON...CLOUD COVER WILL
TEETER ON THE FENCE OF MVFR AND VFR...AS SHOWER DEVELOPMENT
INCREASES...WITH THE POSSIBILITY OF AN ISOLATED THUNDERSTORM AS
WELL. NORTHEAST WINDS WILL CONTINUE...WITH SUSTAINED WINDS AOB 10
KTS. INTO THE EVENING HOURS...WINDS WILL GRADUALLY BECOME
LIGHT...BUT THE OPPORTUNITY FOR ISOLATED SHOWERS WILL
CONTINUE...WITH A PERIOD OF RAIN-FREE SKIES LATE OVERNIGHT. INTO THE
MORNING HOURS...CONFIDENCE IS LOWERED ATTM DUE TO OPACITY OF ANY
STRATUS...THOUGH MID TO HIGH LEVEL CLOUDS WILL BE SCT/BKN. CANNOT
RULE OUT BRIEF HEAVY DOWNPOURS...THUS HAVE KEPT IN TEMPOS TO ACCOUNT
FOR THIS. AFTER MID MORNING...SHOWERS WILL TAPER OFF WITH SKY
COVERAGE GRADUALLY SCATTERING OUT...GIVING WAY TO VFR.
EXTENDED OUTLOOK...ISOLATED SHRA/TS SATURDAY AND MONDAY. SCT
SHRA/TS SUNDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM THURSDAY...NO SIGNIFICANT CHANGES FROM THE PREVIOUS
FORECAST. NE WINDS ARE RUNNING JUST A FEW KNOTS STRONGER THAN
EARLIER THOUGHT NEAR AND NORTH OF CAPE FEAR. PREVIOUS DISCUSSION
FROM 10 AM FOLLOWS...
THE FRONT HAS SLID SOUTH THROUGH VIRTUALLY ALL OF OUR FORECAST AREA
THIS MORNING...EXTENDING FROM APPROXIMATELY 15 MILES EAST OF
GEORGETOWN TO 10 MILES NORTH OF THE FRYING PAN SHOALS TOWER TO ABOUT
70 MILES EAST OF WRIGHTSVILLE BEACH. NORTHEAST WINDS 10-15 KT ON THE
NORTH SIDE OF THE BOUNDARY CONTRAST WITH LIGHT AND VARIABLE WINDS TO
THE SOUTH. EARLIER SHOWERS HAVE LARGELY DISSIPATED WITHIN 20 MILES
OF SHORE EXCEPT IN THE VICINITY OF THE FRONT NEAR FRYING PAN SHOALS.
FOR THE REMAINDER OF TODAY THE LITTLE NE SURGE BEHIND THE SURFACE
FRONT SHOULD WEAKEN THROUGH THE AFTERNOON HOURS WITH WIND SPEEDS
FALLING TO 10 KNOTS OR LESS. WE ANTICIPATE AN INCREASE IN THE
COVERAGE OF SLOW-MOVING SHOWERS AND EMBEDDED THUNDERSTORMS THIS
AFTERNOON ALONG THE COAST...SOME OF WHICH WILL DRIFT OFFSHORE AND
AFFECT THE COASTAL WATERS. WITH VERY LIGHT WINDS AND UNSTABLE AIR
THE POTENTIAL FOR WATERSPOUT DEVELOPMENT REMAINS ELEVATED.
SEAS RANGE FROM 2 FT TO AROUND 3 FT OUT AT THE FRYING PAN SHOALS
BUOY. LITTLE CHANGE IS EXPECTED THROUGH TODAY AND TONIGHT.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...BENIGN CONDITIONS WILL CONTINUE ACROSS THE
WATERS THROUGH THE PERIOD AS A VERY WEAK SURFACE PRESSURE PATTERN
RESIDES ACROSS THE WATERS. A WEAK NORTHEASTERLY FLOW OF LESS THAN
TEN KNOTS BOTH FRIDAY AND SATURDAY. SWAN SEAS SHOW 2-4 FEET AND THE
POSSIBILITY OF SOME FIVE FOOTERS VERY LATE IN THE PERIOD.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM THURSDAY...EXPECT A NORTHEASTERLY FLOW THROUGH MOST OF
THE PERIOD AS SURFACE HIGH PRESSURE...ALIGNED ALONG THE SPINE OF THE
APPALACHIANS IS THE MAIN PLAYER. THE FLOW SHOULD VEER SLIGHTLY LATE
MONDAY AS THE HIGH BREAKS DOWN. SPEEDS GO FROM AROUND TEN KNOTS
INITIALLY TO 10-15 LATE. SEAS INCREASE FROM 2-4 FEET INITIALLY TO
3-5 FEET LATE AS SWELL FROM THE SOUTHEAST INCREASES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...RJD
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...SGL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1241 PM EDT THU AUG 23 2012
.SYNOPSIS...
UPPER LEVEL DISTURBANCES AND A STALLED FRONT OFFSHORE WILL KEEP THE
WEATHER UNSETTLED THROUGH FRIDAY. SOME SLIGHTLY DRIER AIR WILL WORK
INTO THE AREA OVER THE WEEKEND. EARLY NEXT WEEK...ALL EYES WILL BE
FOCUSED ON TROPICAL CYCLONE ISAAC TO OUR SOUTH AND ITS EVENTUAL
TRACK. THE RISK FOR WET WEATHER WILL RETURN DURING TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 PM THURSDAY...I HAVE INCREASED POPS TO "LIKELY" FOR THE
REMAINDER OF THE AFTERNOON ALONG THE COAST FROM JUST SOUTH OF
WILMINGTON THROUGH THE GRAND STRAND...AND ALSO JUST NORTH OF
FLORENCE WHERE A CONCENTRATED BATCH OF SHOWERS RECENTLY HAS
DEVELOPED. OBVIOUSLY A FEW FOLKS UNDER THESE SLOW-MOVING SHOWERS ARE
GOING TO PICK UP SEVERAL INCHES OF RAIN...BUT BROADER SCALE AREAL
AVERAGES SHOULD BE AROUND HALF AN INCH. SYNOPTIC REASONING AS
EXPLAINED EARLIER IN UNCHANGED. PREVIOUS DISCUSSION FROM 10 AM
FOLLOWS...
THE FRONT IS EASILY DISCERNIBLE ON MORNING
VISIBLE SATELLITE IMAGERY AND EXTENDS FROM ABOUT 15 MILES EAST OF
GEORGETOWN TO 10 MILES NORTH OF THE FRYING PAN SHOALS TOWER TO ABOUT
70 MILES EAST OF WRIGHTSVILLE BEACH. THE LIGHT NE FLOW COVERING THE
EASTERN CAROLINAS IS NOT A SIGNIFICANTLY DIFFERENT AIRMASS THAN THAT
FOUND SOUTH OF THE FRONT...AND SHOULD DO NOTHING TO PREVENT SHOWERS
AND EMBEDDED THUNDERSTORMS FROM DEVELOPING LATER TODAY.
A STREAM OF HIGH PRECIPITABLE WATER VALUES EXTENDS FROM THE EASTERN
GULF OF MEXICO NORTHEAST ALONG THE CAROLINA COAST. BLENDED TOTAL
PRECIPITABLE WATER IMAGERY FROM SATELLITE AGREES WITH MODEL ANALYSES
SHOWING 1.80 TO 2.00 INCH PRECIPITABLE WATER OVERHEAD. MID-LEVEL
TEMPERATURES FROM THE 12Z CHS AND MHX SOUNDINGS WERE SURPRISINGLY
COOL...-9 C AT 500 MB...AND LAPSE RATES WERE SLIGHTLY STEEPER THAN
MOIST-ADIABATIC UP THROUGH 300 MB...ALL INDICATIVE OF AN AIRMASS
THAT IS SUITABLE FOR CONVECTION. IT WILL ONLY TAKE TEMPERATURES
REACHING THE LOWER 80S TO IGNITE ANOTHER ROUND OF SCATTERED SHOWERS
AND EMBEDDED THUNDERSTORMS.
THE LATEST THREE HRRR RUNS INDICATE THAT MUCH LIKE YESTERDAY WE CAN
EXPECT THE GREATEST CONCENTRATION OF CONVECTION WITHIN 30-40 MILES
OF THE COAST THIS AFTERNOON. COMPUTED CELL MOTION FROM THE 12Z
SOUNDINGS IS LESS THAN 5 KNOTS...AND BOUNDARY INTERACTIONS WILL MOST
LIKELY OVERWHELM THAT DRIFT AND CREATE VARIABLE AND ERRATIC
EFFECTIVE STORM MOTION. WITH SUCH HIGH PRECIPITABLE WATER VALUES WE
EXPECT LOCALLY HEAVY RAIN TO OCCUR WITH MINOR FLOODING POSSIBLE.
HIGHS SHOULD REACH THE LOWER 80S WITH PERHAPS A FEW MID 80S POSSIBLE
OUT WEST OF FLORENCE.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...MID LEVEL LOW OR REALLY A WEAKNESS WILL
SLOWLY LIFT OUT TO THE NORTHEAST AS A WEAK RIDGE BUILDS ACROSS THE
TENNESSEE VALLEY. HIGH PRESSURE WILL BUILD IN FROM THE NORTHEAST
WITH THE AXIS TO THE WEST ALONG THE APPALACHIANS. THE GFS HAS TRENDED
A LITTLE WETTER AND POPS ARE INCLUDED FOR BOTH FRIDAY AND TO A
LESSER EXTENT SATURDAY. CONTINUED THE RECENT TREND OF GOING ABOVE
THE WARMEST GUIDANCE FOR TEMPERATURES.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 3 AM THURSDAY...FORECAST AREA WILL BE IN A VERY NARROW
WEAKNESS OF MID LEVEL TROUGHING INITIALLY. THIS AREA WILL SLOWLY
DEEPEN AS A SHORTWAVE RIDES ACROSS THE GREAT LAKES AND EVENTUALLY THE
NORTHEAST. THIS WEAKNESS WILL BE THE KEY TO THE EVENTUAL FORECAST OF
ISAAC. AT THE SURFACE...HIGH PRESSURE WILL PREVAIL UNTIL LATE IN THE
PERIOD WHEN CLOUDS AND RAIN INCREASE FROM WHAT REMAINS OF ISAAC. THE
TREND HAS BEEN TO INCREASE CLOUDS AND POPS FOR LATE IN THE PERIOD
WITH THE USUAL DISCLAIMER THAT THE TRACK COULD CHANGE AND AT THIS
POINT THE EMPHASIS WITH THE CLOUDS AND RAIN ARE WITH THE REMNANTS OF
THE SYSTEM. OTHERWISE...SUNDAY SHOULD REMAIN DRY WITH ONLY SLIGHT
CHANCE POPS FOR MONDAY VIA THE SEA BREEZE. NO CHANGES TO THE
TEMPERATURE FORECAST WHICH HOVERS AROUND CLIMATOLOGY FOR HIGHS AND
SLIGHTLY BELOW AT LEAST INITIALLY FOR THE LOWS. THE AFOREMENTIONED
INCREASE IN MOISTURE NARROWS THE DIURNAL RANGE LATE IN THE PERIOD.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 12Z...A STATIONARY FRONT IS LOCATED OFFSHORE WITH NE FLOW IN
THE LOW-LEVELS TO THE WEST OF THE FRONT. WEAK CAA HAS RESULTED IN
A LOW LVL INVERSION WHICH HAS TRAPPED MOISTURE FROM YESTERDAYS RAINS
IN THE 100-300 FOOT RANGE...MAINLY AT THE COAST TERMS AND JUST
INLAND. DUE TO THE LOW CIGS VSBYS HAVE ALSO DROPPED INTO THE
LIFR/IFR RANGE AT CRE/MYR AND MVFR RANGE AT ILM. AT FLO THIS MORNING
THE LOW LVL INVERSION IS LESS PRONOUNCED AND CIGS ARE GENERALLY
MVFR. LBT IS MORE ON THE EDGE OF ALL THE LOW CLOUDINESS. ISOLATED
SHOWERS ARE PERSISTING SE OF THE COAST TERMS.
THE LOW LVL INVERSION SHOULD REMAIN INTACT AT LEAST EARLY THIS
MORNING AS LONG AS NE FLOW CONTINUES. IT MAY BE AS LATE AS 15-16Z AT
CRE/MYR BEFORE IFR CIGS LIFT TO MVFR OR GREATER. TEMPO MVFR CIGS
WILL BE LIKELY AFTERWARD AS CIGS LIFT AND SHRA BEGINS TO DEVELOP.
THE COAST TERMS WILL BE MOST LIKELY TO EXPERIENCE SHRA/ISOLATED TS
TODAY BUT CONFIDENCE OF ANY TIMING IS LOW. WILL INDICATE TEMPO MVFR
CONDITIONS ATTM AND AMEND AS NECESSARY FOR IFR/TS.
THERE IS LESS CHANCE OF DENSE FOG AND STRATUS OVERNIGHT. A MORE
SIGNIFICANT SHORT WAVE WILL BE PASSING WHICH SHOULD PROVIDE COPIOUS
AMOUNTS OF CLOUD COVER...AS WELL AS LIGHT RAIN AT FLO/LBT AND
MODERATE TO HEAVY SHOWERS AT THE COAST TERMS.
EXTENDED OUTLOOK...ISOLATED SHRA/TS FRIDAY...SATURDAY AND MONDAY.
SCT SHRA/TS SUNDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM THURSDAY...NO SIGNIFICANT CHANGES FROM THE PREVIOUS
FORECAST. NE WINDS ARE RUNNING JUST A FEW KNOTS STRONGER THAN
EARLIER THOUGHT NEAR AND NORTH OF CAPE FEAR. PREVIOUS DISCUSSION
FROM 10 AM FOLLOWS...
THE FRONT HAS SLID SOUTH THROUGH VIRTUALLY ALL OF OUR FORECAST AREA
THIS MORNING...EXTENDING FROM APPROXIMATELY 15 MILES EAST OF
GEORGETOWN TO 10 MILES NORTH OF THE FRYING PAN SHOALS TOWER TO ABOUT
70 MILES EAST OF WRIGHTSVILLE BEACH. NORTHEAST WINDS 10-15 KT ON THE
NORTH SIDE OF THE BOUNDARY CONTRAST WITH LIGHT AND VARIABLE WINDS TO
THE SOUTH. EARLIER SHOWERS HAVE LARGELY DISSIPATED WITHIN 20 MILES
OF SHORE EXCEPT IN THE VICINITY OF THE FRONT NEAR FRYING PAN SHOALS.
FOR THE REMAINDER OF TODAY THE LITTLE NE SURGE BEHIND THE SURFACE
FRONT SHOULD WEAKEN THROUGH THE AFTERNOON HOURS WITH WIND SPEEDS
FALLING TO 10 KNOTS OR LESS. WE ANTICIPATE AN INCREASE IN THE
COVERAGE OF SLOW-MOVING SHOWERS AND EMBEDDED THUNDERSTORMS THIS
AFTERNOON ALONG THE COAST...SOME OF WHICH WILL DRIFT OFFSHORE AND
AFFECT THE COASTAL WATERS. WITH VERY LIGHT WINDS AND UNSTABLE AIR
THE POTENTIAL FOR WATERSPOUT DEVELOPMENT REMAINS ELEVATED.
SEAS RANGE FROM 2 FT TO AROUND 3 FT OUT AT THE FRYING PAN SHOALS
BUOY. LITTLE CHANGE IS EXPECTED THROUGH TODAY AND TONIGHT.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...BENIGN CONDITIONS WILL CONTINUE ACROSS THE
WATERS THROUGH THE PERIOD AS A VERY WEAK SURFACE PRESSURE PATTERN
RESIDES ACROSS THE WATERS. A WEAK NORTHEASTERLY FLOW OF LESS THAN
TEN KNOTS BOTH FRIDAY AND SATURDAY. SWAN SEAS SHOW 2-4 FEET AND THE
POSSIBILITY OF SOME FIVE FOOTERS VERY LATE IN THE PERIOD.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM THURSDAY...EXPECT A NORTHEASTERLY FLOW THROUGH MOST OF
THE PERIOD AS SURFACE HIGH PRESSURE...ALIGNED ALONG THE SPINE OF THE
APPALACHIANS IS THE MAIN PLAYER. THE FLOW SHOULD VEER SLIGHTLY LATE
MONDAY AS THE HIGH BREAKS DOWN. SPEEDS GO FROM AROUND TEN KNOTS
INITIALLY TO 10-15 LATE. SEAS INCREASE FROM 2-4 FEET INITIALLY TO
3-5 FEET LATE AS SWELL FROM THE SOUTHEAST INCREASES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...TRA
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...MRR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1029 AM EDT THU AUG 23 2012
.SYNOPSIS...
UPPER LEVEL DISTURBANCES AND A STALLED FRONT OFFSHORE WILL KEEP THE
WEATHER UNSETTLED THROUGH FRIDAY. SOME SLIGHTLY DRIER AIR WILL WORK
INTO THE AREA OVER THE WEEKEND. EARLY NEXT WEEK...ALL EYES WILL BE
FOCUSED ON TROPICAL CYCLONE ISAAC TO OUR SOUTH AND ITS EVENTUAL
TRACK. THE RISK FOR WET WEATHER WILL RETURN DURING TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM THURSDAY...THE FRONT IS EASILY DISCERNIBLE ON MORNING
VISIBLE SATELLITE IMAGERY AND EXTENDS FROM ABOUT 15 MILES EAST OF
GEORGETOWN TO 10 MILES NORTH OF THE FRYING PAN SHOALS TOWER TO ABOUT
70 MILES EAST OF WRIGHTSVILLE BEACH. THE LIGHT NE FLOW COVERING THE
EASTERN CAROLINAS IS NOT A SIGNIFICANTLY DIFFERENT AIRMASS THAN THAT
FOUND SOUTH OF THE FRONT...AND SHOULD DO NOTHING TO PREVENT SHOWERS
AND EMBEDDED THUNDERSTORMS FROM DEVELOPING LATER TODAY.
A STREAM OF HIGH PRECIPITABLE WATER VALUES EXTENDS FROM THE EASTERN
GULF OF MEXICO NORTHEAST ALONG THE CAROLINA COAST. BLENDED TOTAL
PRECIPITABLE WATER IMAGERY FROM SATELLITE AGREES WITH MODEL ANALYSES
SHOWING 1.80 TO 2.00 INCH PRECIPITABLE WATER OVERHEAD. MID-LEVEL
TEMPERATURES FROM THE 12Z CHS AND MHX SOUNDINGS WERE SURPRISINGLY
COOL...-9 C AT 500 MB...AND LAPSE RATES WERE SLIGHTLY STEEPER THAN
MOIST-ADIABATIC UP THROUGH 300 MB...ALL INDICATIVE OF AN AIRMASS
THAT IS SUITABLE FOR CONVECTION. IT WILL ONLY TAKE TEMPERATURES
REACHING THE LOWER 80S TO IGNITE ANOTHER ROUND OF SCATTERED SHOWERS
AND EMBEDDED THUNDERSTORMS.
THE LATEST THREE HRRR RUNS INDICATE THAT MUCH LIKE YESTERDAY WE CAN
EXPECT THE GREATEST CONCENTRATION OF CONVECTION WITHIN 30-40 MILES
OF THE COAST THIS AFTERNOON. COMPUTED CELL MOTION FROM THE 12Z
SOUNDINGS IS LESS THAN 5 KNOTS...AND BOUNDARY INTERACTIONS WILL MOST
LIKELY OVERWHELM THAT DRIFT AND CREATE VARIABLE AND ERRATIC
EFFECTIVE STORM MOTION. WITH SUCH HIGH PRECIPITABLE WATER VALUES WE
EXPECT LOCALLY HEAVY RAIN TO OCCUR WITH MINOR FLOODING POSSIBLE.
HIGHS SHOULD REACH THE LOWER 80S WITH PERHAPS A FEW MID 80S POSSIBLE
OUT WEST OF FLORENCE.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...MID LEVEL LOW OR REALLY A WEAKNESS WILL
SLOWLY LIFT OUT TO THE NORTHEAST AS A WEAK RIDGE BUILDS ACROSS THE
TENNESSEE VALLEY. HIGH PRESSURE WILL BUILD IN FROM THE NORTHEAST
WITH THE AXIS TO THE WEST ALONG THE APPALACHIANS. THE GFS HAS TRENDED
A LITTLE WETTER AND POPS ARE INCLUDED FOR BOTH FRIDAY AND TO A
LESSER EXTENT SATURDAY. CONTINUED THE RECENT TREND OF GOING ABOVE
THE WARMEST GUIDANCE FOR TEMPERATURES.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 3 AM THURSDAY...FORECAST AREA WILL BE IN A VERY NARROW
WEAKNESS OF MID LEVEL TROUGHING INITIALLY. THIS AREA WILL SLOWLY
DEEPEN AS A SHORTWAVE RIDES ACROSS THE GREAT LAKES AND EVENTUALLY THE
NORTHEAST. THIS WEAKNESS WILL BE THE KEY TO THE EVENTUAL FORECAST OF
ISAAC. AT THE SURFACE...HIGH PRESSURE WILL PREVAIL UNTIL LATE IN THE
PERIOD WHEN CLOUDS AND RAIN INCREASE FROM WHAT REMAINS OF ISAAC. THE
TREND HAS BEEN TO INCREASE CLOUDS AND POPS FOR LATE IN THE PERIOD
WITH THE USUAL DISCLAIMER THAT THE TRACK COULD CHANGE AND AT THIS
POINT THE EMPHASIS WITH THE CLOUDS AND RAIN ARE WITH THE REMNANTS OF
THE SYSTEM. OTHERWISE...SUNDAY SHOULD REMAIN DRY WITH ONLY SLIGHT
CHANCE POPS FOR MONDAY VIA THE SEA BREEZE. NO CHANGES TO THE
TEMPERATURE FORECAST WHICH HOVERS AROUND CLIMATOLOGY FOR HIGHS AND
SLIGHTLY BELOW AT LEAST INITIALLY FOR THE LOWS. THE AFOREMENTIONED
INCREASE IN MOISTURE NARROWS THE DIURNAL RANGE LATE IN THE PERIOD.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 12Z...A STATIONARY FRONT IS LOCATED OFFSHORE WITH NE FLOW IN
THE LOW-LEVELS TO THE WEST OF THE FRONT. WEAK CAA HAS RESULTED IN
A LOW LVL INVERSION WHICH HAS TRAPPED MOISTURE FROM YESTERDAYS RAINS
IN THE 100-300 FOOT RANGE...MAINLY AT THE COAST TERMS AND JUST
INLAND. DUE TO THE LOW CIGS VSBYS HAVE ALSO DROPPED INTO THE
LIFR/IFR RANGE AT CRE/MYR AND MVFR RANGE AT ILM. AT FLO THIS MORNING
THE LOW LVL INVERSION IS LESS PRONOUNCED AND CIGS ARE GENERALLY
MVFR. LBT IS MORE ON THE EDGE OF ALL THE LOW CLOUDINESS. ISOLATED
SHOWERS ARE PERSISTING SE OF THE COAST TERMS.
THE LOW LVL INVERSION SHOULD REMAIN INTACT AT LEAST EARLY THIS
MORNING AS LONG AS NE FLOW CONTINUES. IT MAY BE AS LATE AS 15-16Z AT
CRE/MYR BEFORE IFR CIGS LIFT TO MVFR OR GREATER. TEMPO MVFR CIGS
WILL BE LIKELY AFTERWARD AS CIGS LIFT AND SHRA BEGINS TO DEVELOP.
THE COAST TERMS WILL BE MOST LIKELY TO EXPERIENCE SHRA/ISOLATED TS
TODAY BUT CONFIDENCE OF ANY TIMING IS LOW. WILL INDICATE TEMPO MVFR
CONDITIONS ATTM AND AMEND AS NECESSARY FOR IFR/TS.
THERE IS LESS CHANCE OF DENSE FOG AND STRATUS OVERNIGHT. A MORE
SIGNIFICANT SHORT WAVE WILL BE PASSING WHICH SHOULD PROVIDE COPIOUS
AMOUNTS OF CLOUD COVER...AS WELL AS LIGHT RAIN AT FLO/LBT AND
MODERATE TO HEAVY SHOWERS AT THE COAST TERMS.
EXTENDED OUTLOOK...ISOLATED SHRA/TS FRIDAY...SATURDAY AND MONDAY.
SCT SHRA/TS SUNDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM THURSDAY...THE FRONT HAS SLID SOUTH THROUGH VIRTUALLY
ALL OF OUR FORECAST AREA THIS MORNING...EXTENDING FROM APPROXIMATELY
15 MILES EAST OF GEORGETOWN TO 10 MILES NORTH OF THE FRYING PAN
SHOALS TOWER TO ABOUT 70 MILES EAST OF WRIGHTSVILLE BEACH. NORTHEAST
WINDS 10-15 KT ON THE NORTH SIDE OF THE BOUNDARY CONTRAST WITH LIGHT
AND VARIABLE WINDS TO THE SOUTH. EARLIER SHOWERS HAVE LARGELY
DISSIPATED WITHIN 20 MILES OF SHORE EXCEPT IN THE VICINITY OF THE
FRONT NEAR FRYING PAN SHOALS.
FOR THE REMAINDER OF TODAY THE LITTLE NE SURGE BEHIND THE SURFACE
FRONT SHOULD WEAKEN THROUGH THE AFTERNOON HOURS WITH WIND SPEEDS
FALLING TO 10 KNOTS OR LESS. WE ANTICIPATE AN INCREASE IN THE
COVERAGE OF SLOW-MOVING SHOWERS AND EMBEDDED THUNDERSTORMS THIS
AFTERNOON ALONG THE COAST...SOME OF WHICH WILL DRIFT OFFSHORE AND
AFFECT THE COASTAL WATERS. WITH VERY LIGHT WINDS AND UNSTABLE AIR
THE POTENTIAL FOR WATERSPOUT DEVELOPMENT REMAINS ELEVATED.
SEAS RANGE FROM 2 FT TO AROUND 3 FT OUT AT THE FRYING PAN SHOALS
BUOY. LITTLE CHANGE IS EXPECTED THROUGH TODAY AND TONIGHT.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...BENIGN CONDITIONS WILL CONTINUE ACROSS THE
WATERS THROUGH THE PERIOD AS A VERY WEAK SURFACE PRESSURE PATTERN
RESIDES ACROSS THE WATERS. A WEAK NORTHEASTERLY FLOW OF LESS THAN
TEN KNOTS BOTH FRIDAY AND SATURDAY. SWAN SEAS SHOW 2-4 FEET AND THE
POSSIBILITY OF SOME FIVE FOOTERS VERY LATE IN THE PERIOD.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM THURSDAY...EXPECT A NORTHEASTERLY FLOW THROUGH MOST OF
THE PERIOD AS SURFACE HIGH PRESSURE...ALIGNED ALONG THE SPINE OF THE
APPALACHIANS IS THE MAIN PLAYER. THE FLOW SHOULD VEER SLIGHTLY LATE
MONDAY AS THE HIGH BREAKS DOWN. SPEEDS GO FROM AROUND TEN KNOTS
INITIALLY TO 10-15 LATE. SEAS INCREASE FROM 2-4 FEET INITIALLY TO
3-5 FEET LATE AS SWELL FROM THE SOUTHEAST INCREASES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...TRA
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...MRR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
735 AM EDT THU AUG 23 2012
.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL MOVE SLOWLY EAST OVER THE AREA TODAY.
SURFACE HIGH PRESSURE WILL STRENGTHEN OVER THE CAROLINAS AND THE
MID-ATLANTIC FRIDAY AND PERSIST INTO THE WEEKEND.
&&
.NEAR TERM /THROUGH FRIDAY/...
AS OF 310 AM THURSDAY...
AN UPPER LEVEL TROUGH AXIS CONTINUES TO SLOWLY MOVE ACROSS WESTERN
NC...WHILE WATER VAPOR AND RAP 500MB VORT FIELDS SHOW MULTIPLE WEAK
DISTURBANCES MOVING NORTHEAST FROM GA TO EASTERN NC. DESPITE SOME
DRIER AIR ALOFT IN THE VICINITY OF THE TROUGH AXIS.. 00Z/23 RAOBS
FROM AROUND THE REGION SHOWED PLENTY OF MOISTURE BELOW 700MB AND PW
VALUES CONTINUE TO HOVER AROUND 1.5 INCHES. THUS... A ISOLATED
SHOWERS ARE STILL POSSIBLE THROUGH THE EARLY MORNING HOURS.
MEANWHILE...SURFACE HIGH PRESSURE CENTERED OVER WV WILL BUILD EAST
OF THE MOUNTAINS TODAY AND BEGIN TO SETTLE TOWARD NEW ENGLAND
THIS WEEKEND. DEWPOINTS ARE IN THE MID 50S WEST OF THE
MOUNTAINS..AND SOME OF THE DRIER AIR SHOULD BEGIN TO FILTER ACROSS
VA TOWARD NC TODAY. HOWEVER...THERE IS NOT A GOOD CONSENSUS FROM
THE OPERATIONAL MODELS ON HOW QUICKLY THE DRY AIR WILL PENETRATE
INTO NC..AND SREF PLUMES SHOW A RELATIVELY LARGE SPREAD IN DEWPOINTS
RANGING FROM THE UPPER 50S TO MID 60S THIS AFTERNOON. THE LOW LEVEL
FLOW IS NORTHEASTERLY BETWEEN THE HIGH TO THE WEST AND THE INVERTED
TROUGH/FRONTAL ZONE JUST OFFSHORE AND MAY NOT TAP THE DRIER AIR
UNTIL FRIDAY. GIVEN THAT DEWPOINTS MAY HOLD IN THE MID TO UPPER 60S
AND THE FACT THAT THE UPPER LEVEL TROUGH WILL BE MOVING SLOWLY
OVERHEAD AND CUTTING OFF INTO A WEAK UPPER LOW BY TONIGHT...WILL GO
WITH ABOVE MOST GUIDANCE TODAY WITH 30-40 POPS OVER THE COASTAL
PLAIN AND SANDHILLS.
INSTABILITY WILL CONTINUE TO RATHER WEAK WITH ONLY MINIMAL COOLING
ALOFT IN THE UPPER TROUGH....AND THE MID LEVEL FLOW/DEEP SHEAR HAS
WEAKENED TO LESS THAN 25KT. THE MAIN CONCERN FROM CONVECTION TODAY
WILL BE FROM SLOW MOVEMENT/PROPAGATION AND LOCALIZED FLOODING WITH
WEAK NORTHEASTERLY FLOW BENEATH THE SOUTHWESTERLY MID TO UPPER LEVEL
FLOW.
PERSISTENCE SHOULD BE APPROPRIATE FOR HIGHS AGAIN TODAY...LEADING TO
LOW TO MID 80S DEPENDING ON WHERE CLOUDS MID/HIGH CLOUDS THIN THE
MOST.
TONIGHT...
THE STRONGER OF THE UPPER DISTURBANCES EVIDENT UPSTREAM
SHOULD BE MOVING NORTHEAST ACROSS FAR EASTERN NC TONIGHT...SO WHILE
SHOWERS MAY LINGER LATER INTO THE EVENING...THERE SHOULD BE LESS
UPPER SUPPORT AFTER MIDNIGHT AND MOST OF THE AREA DRY. LOWS IN THE
MID 60S.
FRIDAY...
DRIER AIR LOW LEVEL AIR IS FORECAST TO FINALLY MAKE ITS WAY ACROSS
MUCH OF CENTRAL NC FRIDAY...AS HIGH PRESSURE RIDGE SETS UP ALONG THE
EAST COAST. OPERATIONAL MODELS WOULD SUGGEST AT LEAST ISOLATED
SHOWERS/STORMS MAY BE POSSIBLE FROM THE COASTAL PLAIN TO THE
SANDHILLS. THE UPPER LEVEL TROUGH OR WEAK LOW WILL BE OVERHEAD ON
FRIDAY WITH SOME DISTURBANCES POSSIBLY ROTATING ACROSS SC AND NC.
IF DEWPOINTS DO NOT FALL INTO THE LOWER 60S...THEN BETTER....ALBEIT
WEAK...INSTABILITY MAY DEVELOP OVER THE PIEDMONT AND SLIGHT CHANCES
POPS COULD BE WARRANTED OVER THE ENTIRE AREA. QUITE A BIT MORE
SUNSHINE IS EXPECTED FRIDAY AFTERNOON AND HIGHS SHOULD BE 2-3
DEGREES WARMER REACHING THE MID TO UPPER 80S.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
AS OF 145 AM THURSDAY...
FOR FRIDAY NIGHT: THE NORTHERN STREAM SHORTWAVE TROUGH WILL BE
SHIFTING EASTWARD OFF THE CANADIAN MARITIMES... LEAVING THE FORMER
PERSISTENT EAST COAST TROUGH AS SIMPLY A WEAK ILL-DEFINED MID LEVEL
HEIGHT WEAKNESS SITTING OVER THE CAROLINAS. DRIER AIR (PRECIP WATER
SLIPPING BACK JUST UNDER SEASONAL NORMALS) SHOULD CONTINUE TO SLOWLY
FILTER SOUTHWARD INTO CENTRAL NC FROM THE NORTH... FED BY A HIGH
PRESSURE RIDGE EXTENDING FROM ITS CENTER OVER MAINE DOWN THROUGH THE
WRN/CENTRAL CAROLINAS. WEAK VORTICITY LOBES WILL SHEAR UP THE EAST
SIDE OF THE WEAK MID LEVEL LOW OVER COASTAL NC... BUT THE SURFACE
FRONT WILL HAVE SETTLED FAR ENOUGH SOUTHEAST OF THE FORECAST AREA
SUCH THAT IT WILL NOT PLAY A ROLE IN FRIDAY NIGHT`S WEATHER. WITH
THE LOSS OF HEATING AND CORRESPONDING REDUCTION IN INSTABILITY AND
WITH THE LACK OF A TRIGGER TO FORCE ASCENT... ISOLATED EVENING RAIN
CHANCES WILL DIMINISH OVERNIGHT. LIGHT SURFACE WINDS AND DECREASING
MID/HIGH CLOUDS FAVOR GOOD RADIATIONAL COOLING... AND POCKETS OF FOG
ARE POSSIBLE. LOWS 60-65 UNDER GENERALLY FAIR SKIES.
FOR SATURDAY/SATURDAY NIGHT: THE MID LEVEL VORTEX NOW OVER THE BC
COAST WILL PROGRESS EASTWARD THROUGH MANITOBA BY DAYBREAK SUNDAY...
WITH A SIGNIFICANT TROUGH SWEEPING ACROSS THE NORTHERN TIER OF THE
CONUS TO THE UPPER MIDWEST. THIS TROUGH`S APPROACH IS LIKELY TO HELP
NUDGE THE BAGGY LOW OVER THE CAROLINAS SLOWLY NORTHEASTWARD...
RESULTING IN SUBTLE HEIGHT RISES ALOFT OVER THE FORECAST AREA...
WHILE SURFACE RIDGING CONTINUES TO NOSE IN FROM THE NORTHEAST AS ITS
CENTER SHIFTS OFF THE NEW ENGLAND COAST. THE DRY AIR IN PLACE...
LIMITED INSTABILITY (MODEL MLCAPE ALL UNDER 400 J/KG)... AND NEUTRAL
TO SUBSIDING COLUMN SUPPORTS A DRY FORECAST. THE ONLY CAVEAT IS
POSSIBLE SEA BREEZE CONVECTION THAT COULD WORK INTO THE SOUTHEAST
CWA... AND WILL LEAVE A MENTION OF ISOLATED AFTERNOON STORMS HERE.
THE LOW LEVEL THERMAL STRUCTURE FROM FORECAST SOUNDINGS POINTS TO
HIGHS IN THE MID 80S... CLOSE TO THE EARLIER FORECAST AS WELL AS
STATISTICAL GUIDANCE. LOWS 61-66. -GIH
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 240 AM THURSDAY...
THE PATTERN OVER NORTH AMERICA DURING THIS TIME FRAME WILL FEATURE
THE VORTEX OVER THE MANITOBA/ONTARIO BORDER EARLY SUNDAY OPENING UP
WHILE ITS TROUGH SHIFTS EASTWARD ACROSS THE NRN GREAT LAKES/QUEBEC/
ST LAWRENCE VALLEY... CULMINATING IN A LONGWAVE TROUGH COVERING SE
CANADA AND THE NORTHEAST US BY WEDNESDAY. THIS TROUGH (PROPELLED BY
ADDITIONAL ENERGY DIVING INTO ITS BASE FROM THE NW) WILL STEADILY
WEAKEN THE SURFACE RIDGE OVER THE INTERIOR MID ATLANTIC... WHILE
BRINGING A COLD FRONT EASTWARD TOWARD THE APPALACHIANS. WITH SLOWLY
RECOVERING MOISTURE THROUGH THE COLUMN AND BOTH HEIGHT FALLS AND
INCREASING WINDS IN THE MID LEVELS... THE CHANCE FOR DIURNALLY-
DRIVEN SHOWERS AND THUNDERSTORMS WILL GRADUALLY INCREASE THROUGH
THIS PERIOD. OUTSIDE OF THIS PATTERN... OUR ATTENTION TURNS TO WHAT
IS EXPECTED BY THEN TO BE HURRICANE ISAAC. STARTING FROM AN
NHC-PREDICTED POSITION JUST OFF TAMPA FL ON MONDAY AND EXTRAPOLATING
THIS TRACK FOLLOWING THE LARGE SCALE PATTERN AND ENSEMBLE MODEL
GUIDANCE... NC COULD BE AFFECTED BY THE SYSTEM`S RAIN SHIELD BY
TUESDAY NIGHT OR WEDNESDAY. HOWEVER... IT IS FAR TOO EARLY TO
SPECULATE TOO MUCH ON THE TRACK AND PACE OF ISAAC THIS FAR OUT... SO
WILL MAINTAIN A CAUTIOUS APPROACH AT THIS TIME.
EXPECT DRY WEATHER SUNDAY THROUGH MONDAY WITH DRY/SINKING AIR AND
MID LEVEL RIDGING PERSISTING. LOW LEVEL THICKNESSES OVER 15 METERS
BELOW NORMAL SUPPORT HIGHS IN THE LOW-MID 80S SUNDAY. THICKNESSES
BEGIN TO REBOUND MONDAY BACK TOWARD NORMAL... EQUATING TO HIGHS IN
THE MID-UPPER 80S. WILL INDICATE A TREND TOWARD INCREASING MAINLY
AFTERNOON AND EVENING SHOWERS AND STORMS TUESDAY/WEDNESDAY. PEOPLE
IN NC AND THE SOUTHEAST STATES SHOULD CLOSELY MONITOR THE PROGRESS
AND NHC FORECASTS FOR ISAAC OVER THE NEXT SEVERAL DAYS. -GIH
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 735 AM THURSDAY...
MVFR VSBYS ARE MOSTLY FOCUSED OVER THE CENTRAL AND WESTERN
PIEDMONT...IMPACTING TERMINALS FROM KRWI TO KINT. HOWEVER...VSBYS
WILL IMPROVE QUICKLY AFTER 12Z...WITH VFR CONDITIONS AND CLOUD BASES
GENERALLY ABOVE 3500 FT THIS AFTERNOON. AN UPPER LEVEL TROUGH
SLOWLY CROSSING NC FROM THE WEST WILL HELP TO TRIGGER SCATTERED
SHOWERS THIS AFTERNOON AND EVENING...WITH THE HIGHEST PROBABILITIES
SEEMING TO BE AROUND KFAY.
SHOWERS/STORMS ARE DIMINISH BY LATE THIS EVENING....ALTHOUGH MODELS
INDICATE AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS EASTERN NC
AFTER MIDNIGHT...WHICH COULD CONTINUE THE THREAT OF SHOWERS INTO THE
EARLY MORNING HOURS. OTHERWISE...MVFR VSBYS SHOULD ONCE AGAIN
DEVELOP BY 09Z.
OUTLOOK...
HIGH PRESSURE WILL SETTLE OVER THE EASTERN US BY THIS WEEKEND.
OTHER THAN THE POTENTIAL FOR EARLY MORNING FOG OR STRATUS...MAINLY
SUNDAY MORNING...VFR CONDITIONS GENERALLY EXPECTED TO PREVAIL.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...SMITH
SHORT TERM...HARTFIELD
LONG TERM...HARTFIELD
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
310 AM EDT THU AUG 23 2012
.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL MOVE SLOWLY EAST ACROSS THE CAROLINAS
TODAY. SURFACE HIGH PRESSURE WILL STRENGTHEN OVER THE
CAROLINAS AND THE MID-ATLANTIC FRIDAY AND PERSIST INTO THE WEEKEND.
&&
.NEAR TERM /THROUGH FRIDAY/...
AS OF 310 AM THURSDAY...
AN UPPER LEVEL TROUGH AXIS CONTINUES TO SLOWLY MOVE ACROSS WESTERN
NC...WHILE WATER VAPOR AND RAP 500MB VORT FIELDS SHOW MULTIPLE WEAK
DISTURBANCES MOVING NORTHEAST FROM GA TO EASTERN NC. DESPITE SOME
DRIER AIR ALOFT IN THE VICINITY OF THE TROUGH AXIS.. 00Z/23 RAOBS
FROM AROUND THE REGION SHOWED PLENTY OF MOISTURE BELOW 700MB AND PW
VALUES CONTINUE TO HOVER AROUND 1.5 INCHES. THUS... A ISOLATED
SHOWERS ARE STILL POSSIBLE THROUGH THE EARLY MORNING HOURS.
MEANWHILE...SURFACE HIGH PRESSURE CENTERED OVER WV WILL BUILD EAST
OF THE MOUNTAINS TODAY AND BEGIN TO SETTLE TOWARD NEW ENGLAND
THIS WEEKEND. DEWPOINTS ARE IN THE MID 50S WEST OF THE
MOUNTAINS..AND SOME OF THE DRIER AIR SHOULD BEGIN TO FILTER ACROSS
VA TOWARD NC TODAY. HOWEVER...THERE IS NOT A GOOD CONSENSUS FROM
THE OPERATIONAL MODELS ON HOW QUICKLY THE DRY AIR WILL PENETRATE
INTO NC..AND SREF PLUMES SHOW A RELATIVELY LARGE SPREAD IN DEWPOINTS
RANGING FROM THE UPPER 50S TO MID 60S THIS AFTERNOON. THE LOW LEVEL
FLOW IS NORTHEASTERLY BETWEEN THE HIGH TO THE WEST AND THE INVERTED
TROUGH/FRONTAL ZONE JUST OFFSHORE AND MAY NOT TAP THE DRIER AIR
UNTIL FRIDAY. GIVEN THAT DEWPOINTS MAY HOLD IN THE MID TO UPPER 60S
AND THE FACT THAT THE UPPER LEVEL TROUGH WILL BE MOVING SLOWLY
OVERHEAD AND CUTTING OFF INTO A WEAK UPPER LOW BY TONIGHT...WILL GO
WITH ABOVE MOST GUIDANCE TODAY WITH 30-40 POPS OVER THE COASTAL
PLAIN AND SANDHILLS.
INSTABILITY WILL CONTINUE TO RATHER WEAK WITH ONLY MINIMAL COOLING
ALOFT IN THE UPPER TROUGH....AND THE MID LEVEL FLOW/DEEP SHEAR HAS
WEAKENED TO LESS THAN 25KT. THE MAIN CONCERN FROM CONVECTION TODAY
WILL BE FROM SLOW MOVEMENT/PROPAGATION AND LOCALIZED FLOODING WITH
WEAK NORTHEASTERLY FLOW BENEATH THE SOUTHWESTERLY MID TO UPPER LEVEL
FLOW.
PERSISTENCE SHOULD BE APPROPRIATE FOR HIGHS AGAIN TODAY...LEADING TO
LOW TO MID 80S DEPENDING ON WHERE CLOUDS MID/HIGH CLOUDS THIN THE
MOST.
TONIGHT...
THE STRONGER OF THE UPPER DISTURBANCES EVIDENT UPSTREAM
SHOULD BE MOVING NORTHEAST ACROSS FAR EASTERN NC TONIGHT...SO WHILE
SHOWERS MAY LINGER LATER INTO THE EVENING...THERE SHOULD BE LESS
UPPER SUPPORT AFTER MIDNIGHT AND MOST OF THE AREA DRY. LOWS IN THE
MID 60S.
FRIDAY...
DRIER AIR LOW LEVEL AIR IS FORECAST TO FINALLY MAKE ITS WAY ACROSS
MUCH OF CENTRAL NC FRIDAY...AS HIGH PRESSURE RIDGE SETS UP ALONG THE
EAST COAST. OPERATIONAL MODELS WOULD SUGGEST AT LEAST ISOLATED
SHOWERS/STORMS MAY BE POSSIBLE FROM THE COASTAL PLAIN TO THE
SANDHILLS. THE UPPER LEVEL TROUGH OR WEAK LOW WILL BE OVERHEAD ON
FRIDAY WITH SOME DISTURBANCES POSSIBLY ROTATING ACROSS SC AND NC.
IF DEWPOINTS DO NOT FALL INTO THE LOWER 60S...THEN BETTER....ALBEIT
WEAK...ISNTABILITY MAY DEVELOP OVER THE PIEDMONT AND SLIGHT CHANCES
POPS COULD BE WARRANTED OVER THE ENTIRE AREA. QUITE ABIT MORE
SUNSHINE IS EXPECTED FRIDAY AFTERNOON AND HIGHS SHOULD BE 2-3
DEGREES WARMER REACHING THE MID TO UPPER 80S.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
AS OF 145 AM THURSDAY...
FOR FRIDAY NIGHT: THE NORTHERN STREAM SHORTWAVE TROUGH WILL BE
SHIFTING EASTWARD OFF THE CANADIAN MARITIMES... LEAVING THE FORMER
PERSISTENT EAST COAST TROUGH AS SIMPLY A WEAK ILL-DEFINED MID LEVEL
HEIGHT WEAKNESS SITTING OVER THE CAROLINAS. DRIER AIR (PRECIP WATER
SLIPPING BACK JUST UNDER SEASONAL NORMALS) SHOULD CONTINUE TO SLOWLY
FILTER SOUTHWARD INTO CENTRAL NC FROM THE NORTH... FED BY A HIGH
PRESSURE RIDGE EXTENDING FROM ITS CENTER OVER MAINE DOWN THROUGH THE
WRN/CENTRAL CAROLINAS. WEAK VORTICITY LOBES WILL SHEAR UP THE EAST
SIDE OF THE WEAK MID LEVEL LOW OVER COASTAL NC... BUT THE SURFACE
FRONT WILL HAVE SETTLED FAR ENOUGH SOUTHEAST OF THE FORECAST AREA
SUCH THAT IT WILL NOT PLAY A ROLE IN FRIDAY NIGHT`S WEATHER. WITH
THE LOSS OF HEATING AND CORRESPONDING REDUCTION IN INSTABILITY AND
WITH THE LACK OF A TRIGGER TO FORCE ASCENT... ISOLATED EVENING RAIN
CHANCES WILL DIMINISH OVERNIGHT. LIGHT SURFACE WINDS AND DECREASING
MID/HIGH CLOUDS FAVOR GOOD RADIATIONAL COOLING... AND POCKETS OF FOG
ARE POSSIBLE. LOWS 60-65 UNDER GENERALLY FAIR SKIES.
FOR SATURDAY/SATURDAY NIGHT: THE MID LEVEL VORTEX NOW OVER THE BC
COAST WILL PROGRESS EASTWARD THROUGH MANITOBA BY DAYBREAK SUNDAY...
WITH A SIGNIFICANT TROUGH SWEEPING ACROSS THE NORTHERN TIER OF THE
CONUS TO THE UPPER MIDWEST. THIS TROUGH`S APPROACH IS LIKELY TO HELP
NUDGE THE BAGGY LOW OVER THE CAROLINAS SLOWLY NORTHEASTWARD...
RESULTING IN SUBTLE HEIGHT RISES ALOFT OVER THE FORECAST AREA...
WHILE SURFACE RIDGING CONTINUES TO NOSE IN FROM THE NORTHEAST AS ITS
CENTER SHIFTS OFF THE NEW ENGLAND COAST. THE DRY AIR IN PLACE...
LIMITED INSTABILITY (MODEL MLCAPE ALL UNDER 400 J/KG)... AND NEUTRAL
TO SUBSIDING COLUMN SUPPORTS A DRY FORECAST. THE ONLY CAVEAT IS
POSSIBLE SEA BREEZE CONVECTION THAT COULD WORK INTO THE SOUTHEAST
CWA... AND WILL LEAVE A MENTION OF ISOLATED AFTERNOON STORMS HERE.
THE LOW LEVEL THERMAL STRUCTURE FROM FORECAST SOUNDINGS POINTS TO
HIGHS IN THE MID 80S... CLOSE TO THE EARLIER FORECAST AS WELL AS
STATISTICAL GUIDANCE. LOWS 61-66. -GIH
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 240 AM THURSDAY...
THE PATTERN OVER NORTH AMERICA DURING THIS TIME FRAME WILL FEATURE
THE VORTEX OVER THE MANITOBA/ONTARIO BORDER EARLY SUNDAY OPENING UP
WHILE ITS TROUGH SHIFTS EASTWARD ACROSS THE NRN GREAT LAKES/QUEBEC/
ST LAWRENCE VALLEY... CULMINATING IN A LONGWAVE TROUGH COVERING SE
CANADA AND THE NORTHEAST US BY WEDNESDAY. THIS TROUGH (PROPELLED BY
ADDITIONAL ENERGY DIVING INTO ITS BASE FROM THE NW) WILL STEADILY
WEAKEN THE SURFACE RIDGE OVER THE INTERIOR MID ATLANTIC... WHILE
BRINGING A COLD FRONT EASTWARD TOWARD THE APPALACHIANS. WITH SLOWLY
RECOVERING MOISTURE THROUGH THE COLUMN AND BOTH HEIGHT FALLS AND
INCREASING WINDS IN THE MID LEVELS... THE CHANCE FOR DIURNALLY-
DRIVEN SHOWERS AND THUNDERSTORMS WILL GRADUALLY INCREASE THROUGH
THIS PERIOD. OUTSIDE OF THIS PATTERN... OUR ATTENTION TURNS TO WHAT
IS EXPECTED BY THEN TO BE HURRICANE ISAAC. STARTING FROM AN
NHC-PREDICTED POSITION JUST OFF TAMPA FL ON MONDAY AND EXTRAPOLATING
THIS TRACK FOLLOWING THE LARGE SCALE PATTERN AND ENSEMBLE MODEL
GUIDANCE... NC COULD BE AFFECTED BY THE SYSTEM`S RAIN SHIELD BY
TUESDAY NIGHT OR WEDNESDAY. HOWEVER... IT IS FAR TOO EARLY TO
SPECULATE TOO MUCH ON THE TRACK AND PACE OF ISAAC THIS FAR OUT... SO
WILL MAINTAIN A CAUTIOUS APPROACH AT THIS TIME.
EXPECT DRY WEATHER SUNDAY THROUGH MONDAY WITH DRY/SINKING AIR AND
MID LEVEL RIDGING PERSISTING. LOW LEVEL THICKNESSES OVER 15 METERS
BELOW NORMAL SUPPORT HIGHS IN THE LOW-MID 80S SUNDAY. THICKNESSES
BEGIN TO REBOUND MONDAY BACK TOWARD NORMAL... EQUATING TO HIGHS IN
THE MID-UPPER 80S. WILL INDICATE A TREND TOWARD INCREASING MAINLY
AFTERNOON AND EVENING SHOWERS AND STORMS TUESDAY/WEDNESDAY. PEOPLE
IN NC AND THE SOUTHEAST STATES SHOULD CLOSELY MONITOR THE PROGRESS
AND NHC FORECASTS FOR ISAAC OVER THE NEXT SEVERAL DAYS. -GIH
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 140 AM THURSDAY...
MOSTLY VFR CONDITIONS OBSERVED AS OF 05Z...WITH A FEW SITES
REPORTING MVFR VSBYS. SKIES ARE CLEARING OVER THE WESTERN PIEDMONT
AS THE WESTERN EDGE OF THE MAIN MID/HIGH CLOUD SHIELD IS SHIFTING
SLIGHTLY EASTWARD. WITH LOCALLY HEAVY RAIN HAVING FALLEN LAST
EVENING AROUND FORSYTH AND GUILFORD COUNTIES...VSBYS AT KINT AND
KGSO COULD FALL TO IFR AND LIFR IF THE CLEARING PERSISTS.
ELSEWHERE...MOST SITES WILL SEE MVFR VSBYS DEVELOPING BY 09Z...WITH
PATCHY IFR VSBYS AND STRATUS POSSIBLE.
AFTER 12Z...CONDITIONS WILL IMPROVE BY 14Z WITH SCATTERED CUMULI
DEVELOPING. CLOUD BASES WILL BE ABOVE 4K FT AT KINT/KGSO BUT MAY
REMAIN AROUND 3K FT FROM KRDU TO KRWI AND KFAY UNTIL MID AFTERNOON.
THE BEST CHANCE OF SCATTERED SHOWERS AND ISOLATED STORMS WILL BE
OVER THE COASTAL PLAIN AND SOUTHERN PIEDMONT....FROM KRWI TO KFAY TO
KMEB/KAFP THIS AFTERNOON.
OUTLOOK...
THE UPPER LEVEL TROUGH THAT HAS BEEN RESPONSIBLE FOR THE
UNSETTLED WEATHER PATTERN RECENTLY IS EXPECTED TO GRADUALLY WEAKEN
AND LIFT NORTHWARD THROUGH THE END OF THE WEEK. THIS SUGGESTS A
GRADUAL IMPROVEMENT (I.E. FEWER SHOWERS AND T-STORMS) THROUGH THE
WEEKEND...WITH MOSTLY VFR CONDITIONS EXPECTED FOR THE PERIOD.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...SMITH
SHORT TERM...HARTFIELD
LONG TERM...HARTFIELD
AVIATION...KRR/SMITH
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
145 PM EDT THU AUG 23 2012
.SYNOPSIS...
HIGH PRESSURE AND WEAK FLOW DOMINATE THROUGH THE WEEKEND. WEAKENING
FRONT AND ASSOCIATED DISTURBANCE ALOFT PASSES LATE MONDAY INTO
TUESDAY. TO THE SOUTH...TRACKING COURSE/PROGRESS/STRENGTH OF ISAAC.
&&
.NEAR TERM /THROUGH TONIGHT/...
DIURNAL CU HAS DEVELOPED OVER THE HIGHER ELEVATIONS AND OVER PARTS
OF THE LOWLANDS. EXPECT FEW SHOWERS OR STORMS TO FORM ALONG THE
RIDGE TOPS OF CENTRAL AND NORTHERN MOUNTAINS WITH LITTLE MOTION IF
ANY. ANY CONVECTION SHOULD START TO DIE OFF AROUND SUNSET.
PREVIOUS DISCUSSION BELOW...
LATEST RAP SHOWS UPPER TROUGH AXIS HAS FINALLY PASSED TO THE
EAST...WITH ONLY A FEW SPRINKLES STILL REMAINING OVER SOUTHERN
POCAHONTAS COUNTY. HIGH PRESSURE WILL CONTINUE AT THE
SURFACE...WITH A MAINLY WARM AND SUNNY DAY AHEAD. MODELS SHOWING
JUST ENOUGH MOISTURE THIS AFTERNOON...AND SOME WEAK BOUNDARY LAYER
CONVERGENCE/UPSLOPE FLOW IN THE WV MOUNTAINS...SO ADDED SOME
SCATTERED POPS...AND EXPANDED THE ISOLATED POPS A LITTLE IN OUR
EXTREME EASTERN ZONES. AS THE SLOW WARMING TREND
CONTINUES...EXPECT TODAY TO BE A DEGREE OR TWO WARMER THAN
YESTERDAY. PREVIOUS FORECAST FOR TODAYS HIGHS LOOKED GOOD AND MADE
NO SIGNIFICANT CHANGES THERE. ONLY SMALL ADJUSTMENTS MADE TO
TONIGHT LOWS AS WELL BY BLENDING IN THE MET WHICH HAS BEEN
OUTPERFORMING THE MAV FOR LOWS RECENTLY. THIS RESULTED IN A BIT
WARMER FORECAST IN THE NORTHERN MOUNTAIN ZONES.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
NO BIG CHANGES. DID DECIDE TO INCLUDE A SMALL 30 POP EMBEDDED IN
THE SLIGHT CHANCE 20 POP AREA...THAT WE HAVE BEEN CONSISTENCY RIDING
WITH FOR FRIDAY AND SATURDAY AFTERNOON AND EVENING. FORECAST
SOUNDINGS STILL INDICATE THE HEATING AND WEAK FLOW COULD CAUSE SOME
MOUNTAIN THERMALS TO BREAK THROUGH THE MID LEVEL CAP. WITH A WEAK
DRIFT POSSIBLE OFF THE MOUNTAINS TO THE WEST...DID INCLUDE A SLIGHT
CHANCE POP REACHING BACK TOWARD INTERSTATE 79 AND CORRIDOR G IN WV
BY LATE AFTERNOON OR EARLY EVENING.
BUT THE MAIN THEME CONTINUES TO THE THE WARM AFTERNOONS. DID
INCREASE MAXIMUM TEMPERATURES A FEW DEGREES IN SOME OF THE WESTERN
RIVER VALLEYS FOR FRIDAY AND SATURDAY...WITH THE DRY GROUND.
ANY WEAK UPSLOPE FLOW AT 925/850 MB SEEMS TO BE GONE BY SUNDAY. SO
MOST POPS AOB 14 PERCENT FOR SUNDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
LOW LEVEL FLOW BECOMES MORE SOUTHERLY SATURDAY NIGHT...AS A LOW
PRESSURE SYSTEM APPROACHES THE GREAT LAKES REGION. THIS FLOW WILL
BRING WARMER AIR INTO THE AREA SAT NIGHT...PER GFS SOLUTION. THE
ECMWF IS SLOWER AND FURTHER SOUTH WITH THE SFC LOW PRESSURE SYSTEM
MOVING IT INTO THE OH VALLEY BY 12Z MONDAY.
MEANTIME...SFC HIGH PRESSURE WILL KEEP WARM AND DRY WEATHER
THROUGH AT LEAST MONDAY. HOWEVER...INTRODUCE SLIGHT CHANCE POPS ON
MONDAY PER GFS SOLN...AND BRING CHANCE POPS FOR TUESDAY WITH A
COLD FRONT PASSING THROUGH. UNCERTAINTY WITH THIS SYSTEM
EXIST...SO EXPECT CHANGES IN THE NEXT COUPLE OF DAYS.
ROLLED WITH HPC TEMPERATURES THROUGH THE PERIOD.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
DIURNAL HEATING WILL CONTINUE TO PRODUCE SCATTERED LOW LEVEL CU
ABOUT 4K FEET ACROSS MOST AREAS EAST OF THE OH RIVER. ISOLATED TO
WIDELY SCATTERED SHOWERS WILL DEVELOP ALONG THE HIGHER MOUNTAINS
THIS AFTERNOON TO PRODUCE MVFR UNDER MODERATE RAIN. THESE STORMS
WILL BE SLOW MOVERS...BUT ARE NOT EXPECTED TO BE LONG LIVED OR AS
STRONG TO PRODUCE WIDESPREAD OR SIGNIFICANT PERIODS OF IFR
CONDITIONS. THEREFORE...INCLUDED VCTS AT BKW FOR NOW.
SKIES WILL CLEAR TONIGHT WITH DRIER AIR FILTERING IN FROM THE
WEST. RADIATIONAL COOLING COULD PRODUCE...ONCE AGAIN DENSE VALLEY
FOG MAINLY AT EKN...CRW AND CKB AFTER 08Z THROUGH 12Z. MVFR FOG IS
EXPECTED TO IMPACT THE REST OF SITES PER DRIER AIR AND LACK OF
ANTECEDENT PCPN.
ALL SITES IMPROVE TO VFR AFTER 13Z FRIDAY MORNING.
AN UPPER LEVEL VORT MAX APPROACHES FROM THE EAST INTO THE
APPALACHIAN LATE FRIDAY. THIS FEATURE COULD ENHANCE HIGHER TERRAIN
CONVECTION FRIDAY AFTERNOON. THEREFORE...KEPT THE POSSIBILITY OF
HAVING ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS TO DRIFT
WEST...PERHAPS REACHING CRW AND CKB INTO THE EVENING HOURS.
ATTM...CHANCES ARE LOW...SO DID NOT MENTION THESE CONDITIONS IN
TAF.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY...
FORECAST CONFIDENCE: HIGH.
ALTERNATE SCENARIOS: TIMING AND EXTENT OF FOG COULD VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 18Z FRIDAY...
NO WIDESPREAD IFR CONDITIONS EXPECTED.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...KTB/MZ
NEAR TERM...ARJ/MZ
SHORT TERM...KTB
LONG TERM...ARJ
AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
616 AM EDT THU AUG 23 2012
.SYNOPSIS...
HIGH PRESSURE AND WEAK FLOW DOMINATE THROUGH THE WEEKEND. WEAKENING
FRONT AND ASSOCIATED DISTURBANCE ALOFT PASSES LATE MONDAY INTO
TUESDAY. TO THE SOUTH...TRACKING COURSE/PROGRESS/STRENGTH OF ISAAC.
&&
.NEAR TERM /THROUGH TONIGHT/...LATEST RAP SHOWS UPPER TROUGH AXIS
HAS FINALLY PASSED TO THE EAST...WITH ONLY A FEW SPRINKLES STILL
REMAINING OVER SOUTHERN POCAHONTAS COUNTY. HIGH PRESSURE WILL
CONTINUE AT THE SURFACE...WITH A MAINLY WARM AND SUNNY DAY AHEAD.
MODELS SHOWING JUST ENOUGH MOISTURE THIS AFTERNOON...AND SOME WEAK
BOUNDARY LAYER CONVERGENCE/UPSLOPE FLOW IN THE WV MOUNTAINS...SO
ADDED SOME SCATTERED POPS...AND EXPANDED THE ISOLATED POPS A
LITTLE IN OUR EXTREME EASTERN ZONES. AS THE SLOW WARMING TREND
CONTINUES...EXPECT TODAY TO BE A DEGREE OR TWO WARMER THAN
YESTERDAY. PREVIOUS FORECAST FOR TODAYS HIGHS LOOKED GOOD AND MADE
NO SIGNIFICANT CHANGES THERE. ONLY SMALL ADJUSTMENTS MADE TO
TONIGHT LOWS AS WELL BY BLENDING IN THE MET WHICH HAS BEEN
OUTPERFORMING THE MAV FOR LOWS RECENTLY. THIS RESULTED IN A BIT
WARMER FORECAST IN THE NORTHERN MOUNTAIN ZONES.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
NO BIG CHANGES. DID DECIDE TO INCLUDE A SMALL 30 POP EMBEDDED IN
THE SLIGHT CHANCE 20 POP AREA...THAT WE HAVE BEEN CONSISTENCY RIDING
WITH FOR FRIDAY AND SATURDAY AFTERNOON AND EVENING. FORECAST
SOUNDINGS STILL INDICATE THE HEATING AND WEAK FLOW COULD CAUSE SOME
MOUNTAIN THERMALS TO BREAK THROUGH THE MID LEVEL CAP. WITH A WEAK
DRIFT POSSIBLE OFF THE MOUNTAINS TO THE WEST...DID INCLUDE A SLIGHT
CHANCE POP REACHING BACK TOWARD INTERSTATE 79 AND CORRIDOR G IN WV
BY LATE AFTERNOON OR EARLY EVENING.
BUT THE MAIN THEME CONTINUES TO THE THE WARM AFTERNOONS. DID
INCREASE MAXIMUM TEMPERATURES A FEW DEGREES IN SOME OF THE WESTERN
RIVER VALLEYS FOR FRIDAY AND SATURDAY...WITH THE DRY GROUND.
ANY WEAK UPSLOPE FLOW AT 925/850 MB SEEMS TO BE GONE BY SUNDAY. SO
MOST POPS AOB 14 PERCENT FOR SUNDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
LOW LEVEL FLOW BECOMES MORE SOUTHERLY SATURDAY NIGHT...AS A LOW
PRESSURE SYSTEM APPROACHES THE GREAT LAKES REGION. THIS FLOW WILL
BRING WARMER AIR INTO THE AREA SAT NIGHT...PER GFS SOLUTION. THE
ECMWF IS SLOWER AND FURTHER SOUTH WITH THE SFC LOW PRESSURE SYSTEM
MOVING IT INTO THE OH VALLEY BY 12Z MONDAY.
MEANTIME...SFC HIGH PRESSURE WILL KEEP WARM AND DRY WEATHER
THROUGH AT LEAST MONDAY. HOWEVER...INTRODUCE SLIGHT CHANCE POPS ON
MONDAY PER GFS SOLN...AND BRING CHANCE POPS FOR TUESDAY WITH A
COLD FRONT PASSING THROUGH. UNCERTAINTY WITH THIS SYSTEM
EXIST...SO EXPECT CHANGES IN THE NEXT COUPLE OF DAYS.
ROLLED WITH HPC TEMPERATURES THROUGH THE PERIOD.
&&
.AVIATION /10Z THURSDAY THROUGH MONDAY/...
IFR TO LIFR FOG CURRENTLY IMPACTING SEVERAL TAF SITES...WITH OTHERS
STILL MVFR. EXPECT LIKE YESTERDAY MORNING...WILL GET A QUICK DROP
AT THE MVFR SITES INTO AT LEAST IFR JUST BEFORE SUNRISE...BEFORE
ALL SITES IMPROVE TO VFR FOR THE REST OF THE DAY WITH LIGHT WINDS
AT THE SURFACE AND ALOFT.
THERE SHOULD AGAIN BE SOME ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS OVER MOUNTAINS THIS AFTERNOON. EXPECTING A REPEAT OF
FOG AGAIN TONIGHT INTO EARLY FRIDAY MORNING...WITH DENSE FOG
SHOWING UP AT KEKN BY 09Z AND AT OTHER FOG PRONE SITES BY 10Z-11Z.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING AND EXTENT OF FOG COULD VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE THU 08/23/12
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EDT 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15
CRW CONSISTENCY M M H H L H H H H H H H
HTS CONSISTENCY H H H L L H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY L L L L L M H H H H H H
PKB CONSISTENCY H H M L L H H H H H H H
CKB CONSISTENCY L L L L L H H H H H H H
AFTER 12Z FRIDAY...
NO SIGNIFICANT IFR EXPECTED.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...KTB/MZ
NEAR TERM...MZ
SHORT TERM...KTB
LONG TERM...ARJ
AVIATION...MZ
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
345 AM EDT THU AUG 23 2012
.SYNOPSIS...
HIGH PRESSURE AND WEAK FLOW DOMINATE THROUGH THE WEEKEND. WEAKENING
FRONT AND ASSOCIATED DISTURBANCE ALOFT PASSES LATE MONDAY INTO
TUESDAY. TO THE SOUTH...TRACKING COURSE/PROGRESS/STRENGTH OF ISAAC.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST RAP SHOWS UPPER TROUGH AXIS HAS FINALLY PASSED TO THE
EAST...WITH ONLY A FEW SPRINKLES STILL REMAINING OVER SOUTHERN
POCAHONTAS COUNTY. HIGH PRESSURE WILL CONTINUE AT THE
SURFACE...WITH A MAINLY WARM AND SUNNY DAY AHEAD. MODELS SHOWING
JUST ENOUGH MOISTURE THIS AFTERNOON...AND SOME WEAK BOUNDARY LAYER
CONVERGENCE/UPSLOPE FLOW IN THE WV MOUNTAINS...SO ADDED SOME
SCATTERED POPS...AND EXPANDED THE ISOLATED POPS A LITTLE IN OUR
EXTREME EASTERN ZONES. AS THE SLOW WARMING TREND CONTINUES...EXPECT
TODAY TO BE A DEGREE OR TWO WARMER THAN YESTERDAY. PREVIOUS FORECAST
FOR TODAYS HIGHS LOOKED GOOD AND MADE NO SIGNIFICANT CHANGES THERE.
ONLY SMALL ADJUSTMENTS MADE TO TONIGHT LOWS AS WELL BY BLENDING IN
THE MET WHICH HAS BEEN OUTPERFORMING THE MAV FOR LOWS RECENTLY. THIS
RESULTED IN A BIT WARMER FORECAST IN THE NORTHERN MOUNTAIN ZONES.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
NO BIG CHANGES. DID DECIDE TO INCLUDE A SMALL 30 POP EMBEDDED IN
THE SLIGHT CHANCE 20 POP AREA...THAT WE HAVE BEEN CONSISTENCY RIDING
WITH FOR FRIDAY AND SATURDAY AFTERNOON AND EVENING. FORECAST
SOUNDINGS STILL INDICATE THE HEATING AND WEAK FLOW COULD CAUSE SOME
MOUNTAIN THERMALS TO BREAK THROUGH THE MID LEVEL CAP. WITH A WEAK
DRIFT POSSIBLE OFF THE MOUNTAINS TO THE WEST...DID INCLUDE A SLIGHT
CHANCE POP REACHING BACK TOWARD INTERSTATE 79 AND CORRIDOR G IN WV
BY LATE AFTERNOON OR EARLY EVENING.
BUT THE MAIN THEME CONTINUES TO THE THE WARM AFTERNOONS. DID
INCREASE MAXIMUM TEMPERATURES A FEW DEGREES IN SOME OF THE WESTERN
RIVER VALLEYS FOR FRIDAY AND SATURDAY...WITH THE DRY GROUND.
ANY WEAK UPSLOPE FLOW AT 925/850 MB SEEMS TO BE GONE BY SUNDAY. SO
MOST POPS AOB 14 PERCENT FOR SUNDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
LOW LEVEL FLOW BECOMES MORE SOUTHERLY SATURDAY NIGHT...AS A LOW
PRESSURE SYSTEM APPROACHES THE GREAT LAKES REGION. THIS FLOW WILL
BRING WARMER AIR INTO THE AREA SAT NIGHT...PER GFS SOLUTION. THE
ECMWF IS SLOWER AND FURTHER SOUTH WITH THE SFC LOW PRESSURE SYSTEM
MOVING IT INTO THE OH VALLEY BY 12Z MONDAY.
MEANTIME...SFC HIGH PRESSURE WILL KEEP WARM AND DRY WEATHER
THROUGH AT LEAST MONDAY. HOWEVER...INTRODUCE SLIGHT CHANCE POPS ON
MONDAY PER GFS SOLN...AND BRING CHANCE POPS FOR TUESDAY WITH A
COLD FRONT PASSING THROUGH. UNCERTAINTY WITH THIS SYSTEM
EXIST...SO EXPECT CHANGES IN THE NEXT COUPLE OF DAYS.
ROLLED WITH HPC TEMPERATURES THROUGH THE PERIOD.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
BASED ON T/TD SPREAD SIMILAR TO LAST NIGHT...LARGELY BASED DENSE FOG
FORMATION ON WHAT HAPPENED LAST NIGHT. ONE MAJOR EXCEPTION IS KPKB
WHERE THE DEW POINT IS A COUPLE DEGREES LOWER THAN THIS TIME LAST
NIGHT...SO DELAYED ONSET OF FOG THERE JUST A BIT. AT ANY
RATE...EXPECTING DROPS INTO IFR/LIFR BETWEEN 08Z AND 10Z...WITH THE
EXCEPTION OF KBKW.
VFR SHOULD RETURN 12Z-13Z AS FOG DISSIPATES...WITH VFR AND LIGHT
FLOW EXPECTED FOR THE REST OF THE DAY. THERE SHOULD AGAIN BE SOME
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS OVER MOUNTAINS THIS
AFTERNOON.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING AND EXTENT OF FOG COULD VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE THU 08/23/12
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EDT 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15
CRW CONSISTENCY M M H H L H H H H H H H
HTS CONSISTENCY H H H L L H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY L L L L L M H H H H H H
PKB CONSISTENCY H H M L L H H H H H H H
CKB CONSISTENCY L L L L L H H H H H H H
AFTER 06Z FRIDAY...
NO SIGNIFICANT IFR EXPECTED.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...KTB/MZ
NEAR TERM...MZ
SHORT TERM...KTB
LONG TERM...ARJ
AVIATION...MZ
AREA FORECAST DISCUSSION
NWS NORMAN OK
1254 PM CDT THU AUG 23 2012
.AVIATION...
MAINLY VFR CONDITIONS WILL PREVAIL NEXT 24 HRS WITH
EXCEPTION OF MVFR CEILINGS/VISIBILITIES NEAR CLOSE
TO WIDELY SCATTERED/SCATTERED STORMS.
AREA OF SHOWERS AND EMBEDDED STORMS ACROSS NORTHWEST/
WEST CENTRAL OKLAHOMA EARLIER...HAS BEEN ON THE
DECREASE WITH RESPECT TO COVERAGE AND INTENSITY.
OTHER ISOLATED STORMS OVER CENTRAL OKLAOMA EARLY
THIS AFTERNOON SHOULD GRADUALLY WEAKEN AND MOVE
EAST.
UNTIL MAIN SYSTEM MOVES ACROSS THE SOUTHERN PLAINS
THIS WEEKEND...WILL LIKELY SEE AREAS OF SHOWERS/STORMS
FORM...ESPECIALLY NEAR STRONGER LOW LEVEL FLOW AND
MOIST MID-LEVEL WAA. THROUGH 18Z FRIDAY...THIS SHOULD
FAVOR TAF SITES CSM/WWR/GAG AND PERHAPS PNC.
&&
.PREV DISCUSSION... /ISSUED 905 AM CDT THU AUG 23 2012/
UPDATE...
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP AND MOVE ACROSS
WESTERN PORTIONS OF THE FA THIS MORNING. THE ACTIVITY IS EXPECTED
TO WEAKEN LATER THIS MORNING/EARLY AFTERNOON. HAVE ADJUSTED POPS
TO ACCOUNT FOR CURRENT ACTIVITY. SKIES WILL BE CLOUDY/MOSTLY
CLOUDY ACROSS MUCH OF THE AREA THIS MORNING. WILL SEND UPDATES
SHORTLY.
MAXWELL
PREV DISCUSSION... /ISSUED 645 AM CDT THU AUG 23 2012/
AVIATION...
SCATTERED SHRA/TSRA HAVE DEVELOPED EARLY THIS MORNING AS AN UPPER
DISTURBANCE MOVED INTO OKLAHOMA. THIS ACTIVITY WILL LIKELY LINGER
INTO THE EARLY AFTERNOON...WITH ISOLATED TSRA POSSIBLE INTO PARTS
OF NORTHERN AND CENTRAL OKLAHOMA BY LATE AFTERNOON. BRIEF MVFR
VSBYS WILL BE POSSIBLE WITH THESE STORMS...ESPECIALLY AT KCSM AND
KHBR...WITH LOWER PROBABILITIES AT KOKC...KOUN...AND KLAW. EXPECT
MORE WIDESPREAD SHRA WITH EMBEDDED TSRA ACROSS PORTIONS OF
NORTHERN AND WESTERN OKLAHOMA THIS EVENING AND
OVERNIGHT...SPREADING INTO CENTRAL OK BY 12Z FRIDAY. WILL INCLUDE
PROB30 GROUPS AT MOST SITES AS EXACT TIMING AND COVERAGE OF
SHRA/TSRA REMAINS IN QUESTION. OUTSIDE OF OCCASIONALSTORMS...GUSTY
SOUTH TO SOUTHWEST WINDS ARE EXPECTED THIS AFTERNOON THROUGH THIS
EVENING.
PREV DISCUSSION... /ISSUED 342 AM CDT THU AUG 23 2012/
DISCUSSION...
WIDESPREAD MID AND HIGH CLOUDS OVERSPREAD MUCH OF THE REGION AS A
WEAK UPPER DISTURBANCE MOVES SOUTHWARD THROUGH THE FLOW. AS THIS
CONTINUE TO MOVE SOUTHWARD ACROSS THE REGION...MODEST MID LEVEL
ASCENT MAY ALLOW FOR VERY ISOLATED SHOWERS AND PERHAPS A STORM OR
TWO. RECENT RUNS OF THE HRRR DEPICT A LARGE AREA OF SHOWER AND
THUNDERSTORM ACTIVITY DEVELOPING BY 10Z TO 11Z OVER WESTERN
OKLAHOMA AND NORTH TEXAS. CONFIDENCE IS LOW IN THIS SCENARIO AND
WILL MAINTAIN ONLY SLIGHT CHANCE POPS THROUGH 12Z THIS MORNING.
SHOWERS AND STORMS SHOULD DEVELOP THIS MORNING OVER WESTERN
OKLAHOMA AND PERSIST INTO TONIGHT...SPREADING EASTWARD WITH TIME.
EXPECT THE BEST CHANCES TO REMAIN OVER NORTHWEST OKLAHOMA. AS
SUCH...DAYTIME MAX TEMPS WILL BE A FEW DEGREES COOLER ACROSS
WESTERN OKLAHOMA AND WESTERN NORTH TEXAS.
THE FORECAST THROUGH THE WEEKEND REMAINS GENERALLY UNCHANGED AS
MODELS CONTINUE TO SUGGEST WIDESPREAD PRECIP WITH A SERIES OF
UPPER WAVES TRANSLATING EWD ACROSS THE SOUTHERN PLAINS. PERHAPS
THE MOST POTENT OF THESE WILL MOVE THROUGH TOMORROW AFTERNOON
THROUGH SUNDAY MORNING...GENERATING WIDESPREAD SHOWERS AND STORMS
ALONG WITH LOCALLY HEAVY RAINFALL. THE GREATEST RAINFALL TOTALS
WILL LIKELY REMAIN ACROSS NORTHERN OKLAHOMA NEAR THE KANSAS
OKLAHOMA BORDER. HERE...ISOLATED AREAS MAY SEE UP TO 2.5 TO 3
INCHES OF RAIN. ELSEWHERE...TOTAL RAINFALL ACCUMULATION WILL RANGE
FROM AROUND AN INCH TO 2 INCHES THROUGH THE WEEKEND. PERHAPS THE
ONLY MINOR CHANGE TO THE FORECAST IS IN THE TIMING OF A SFC FRONT
SET TO PUSH THROUGH THE REGION LATE THIS WEEKEND INTO EARLY NEXT
WEEK. RECENT GFS/EURO HAVE COME IN A BIT FASTER WITH FRONTAL
PASSAGE AND WILL NUDGE FRONTAL POSITION AND ASSOCIATED RAIN
CHANCES SOUTHEASTWARD THROUGH MONDAY. WITH MANY AREAS SEEING
PERSISTENT CLOUD COVER AND SHOWER ACTIVITY...HIGH TEMPS WILL
LIKELY BE SEVERAL DEGREES BELOW AVERAGE...WITH SOME LOCATIONS
REMAINING IN THE UPPER 70S FRIDAY INTO SATURDAY.
HEADING INTO NEXT WEEK...UPPER RIDGE WILL BUILD BACK INTO THE
SOUTHERN PLAINS...THOUGH NOT TO THE STRENGTH IT DID IN JULY WHEN
WE WERE PLAGUED WITH PERSISTENT TRIPLE DIGIT TEMPERATURES.
STILL...MODEST RIDGING ALOFT WILL DIMINISH RAIN CHANCES AND LEAD
TO MORE SEASONABLE HIGH TEMPERATURES.
THE HURRICANE CENTER CONTINUES TO FORECAST TROPICAL STORM ISAAC
WILL TAKE A MORE EASTWARD PATH...ULTIMATELY MAKING LANDFALL
SOMEWHERE ALONG THE NORTHEAST GULF COAST. AS ISAAC REMAINS
SOMEWHAT DISORGANIZED...THE EXACT TRACK WILL BE VERY DIFFICULT
PINPOINT. THUS...IT REMAINS UNKNOWN IF ISAAC WILL HAVE ANY IMPACT
ALONG THE CENTRAL GULF COASTAL REGION OR ULTIMATELY THE SOUTHERN
PLAINS.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 69 86 72 84 / 40 50 60 60
HOBART OK 68 89 70 89 / 40 50 50 30
WICHITA FALLS TX 70 91 74 93 / 30 30 30 30
GAGE OK 68 90 69 85 / 50 50 60 50
PONCA CITY OK 69 85 71 79 / 50 50 60 70
DURANT OK 68 89 73 90 / 10 20 40 60
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS NORMAN OK
905 AM CDT THU AUG 23 2012
.UPDATE...
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP AND MOVE ACROSS
WESTERN PORTIONS OF THE FA THIS MORNING. THE ACTIVITY IS EXPECTED
TO WEAKEN LATER THIS MORNING/EARLY AFTERNOON. HAVE ADJUSTED POPS
TO ACCOUNT FOR CURRENT ACTIVITY. SKIES WILL BE CLOUDY/MOSTLY
CLOUDY ACROSS MUCH OF THE AREA THIS MORNING. WILL SEND UPDATES
SHORTLY.
MAXWELL
&&
.PREV DISCUSSION... /ISSUED 645 AM CDT THU AUG 23 2012/
AVIATION...
SCATTERED SHRA/TSRA HAVE DEVELOPED EARLY THIS MORNING AS AN UPPER
DISTURBANCE MOVED INTO OKLAHOMA. THIS ACTIVITY WILL LIKELY LINGER
INTO THE EARLY AFTERNOON...WITH ISOLATED TSRA POSSIBLE INTO PARTS
OF NORTHERN AND CENTRAL OKLAHOMA BY LATE AFTERNOON. BRIEF MVFR
VSBYS WILL BE POSSIBLE WITH THESE STORMS...ESPECIALLY AT KCSM AND
KHBR...WITH LOWER PROBABILITIES AT KOKC...KOUN...AND KLAW. EXPECT
MORE WIDESPREAD SHRA WITH EMBEDDED TSRA ACROSS PORTIONS OF
NORTHERN AND WESTERN OKLAHOMA THIS EVENING AND
OVERNIGHT...SPREADING INTO CENTRAL OK BY 12Z FRIDAY. WILL INCLUDE
PROB30 GROUPS AT MOST SITES AS EXACT TIMING AND COVERAGE OF
SHRA/TSRA REMAINS IN QUESTION. OUTSIDE OF OCCASIONALSTORMS...GUSTY
SOUTH TO SOUTHWEST WINDS ARE EXPECTED THIS AFTERNOON THROUGH THIS
EVENING.
PREV DISCUSSION... /ISSUED 342 AM CDT THU AUG 23 2012/
DISCUSSION...
WIDESPREAD MID AND HIGH CLOUDS OVERSPREAD MUCH OF THE REGION AS A
WEAK UPPER DISTURBANCE MOVES SOUTHWARD THROUGH THE FLOW. AS THIS
CONTINUE TO MOVE SOUTHWARD ACROSS THE REGION...MODEST MID LEVEL
ASCENT MAY ALLOW FOR VERY ISOLATED SHOWERS AND PERHAPS A STORM OR
TWO. RECENT RUNS OF THE HRRR DEPICT A LARGE AREA OF SHOWER AND
THUNDERSTORM ACTIVITY DEVELOPING BY 10Z TO 11Z OVER WESTERN
OKLAHOMA AND NORTH TEXAS. CONFIDENCE IS LOW IN THIS SCENARIO AND
WILL MAINTAIN ONLY SLIGHT CHANCE POPS THROUGH 12Z THIS MORNING.
SHOWERS AND STORMS SHOULD DEVELOP THIS MORNING OVER WESTERN
OKLAHOMA AND PERSIST INTO TONIGHT...SPREADING EASTWARD WITH TIME.
EXPECT THE BEST CHANCES TO REMAIN OVER NORTHWEST OKLAHOMA. AS
SUCH...DAYTIME MAX TEMPS WILL BE A FEW DEGREES COOLER ACROSS
WESTERN OKLAHOMA AND WESTERN NORTH TEXAS.
THE FORECAST THROUGH THE WEEKEND REMAINS GENERALLY UNCHANGED AS
MODELS CONTINUE TO SUGGEST WIDESPREAD PRECIP WITH A SERIES OF
UPPER WAVES TRANSLATING EWD ACROSS THE SOUTHERN PLAINS. PERHAPS
THE MOST POTENT OF THESE WILL MOVE THROUGH TOMORROW AFTERNOON
THROUGH SUNDAY MORNING...GENERATING WIDESPREAD SHOWERS AND STORMS
ALONG WITH LOCALLY HEAVY RAINFALL. THE GREATEST RAINFALL TOTALS
WILL LIKELY REMAIN ACROSS NORTHERN OKLAHOMA NEAR THE KANSAS
OKLAHOMA BORDER. HERE...ISOLATED AREAS MAY SEE UP TO 2.5 TO 3
INCHES OF RAIN. ELSEWHERE...TOTAL RAINFALL ACCUMULATION WILL RANGE
FROM AROUND AN INCH TO 2 INCHES THROUGH THE WEEKEND. PERHAPS THE
ONLY MINOR CHANGE TO THE FORECAST IS IN THE TIMING OF A SFC FRONT
SET TO PUSH THROUGH THE REGION LATE THIS WEEKEND INTO EARLY NEXT
WEEK. RECENT GFS/EURO HAVE COME IN A BIT FASTER WITH FRONTAL
PASSAGE AND WILL NUDGE FRONTAL POSITION AND ASSOCIATED RAIN
CHANCES SOUTHEASTWARD THROUGH MONDAY. WITH MANY AREAS SEEING
PERSISTENT CLOUD COVER AND SHOWER ACTIVITY...HIGH TEMPS WILL
LIKELY BE SEVERAL DEGREES BELOW AVERAGE...WITH SOME LOCATIONS
REMAINING IN THE UPPER 70S FRIDAY INTO SATURDAY.
HEADING INTO NEXT WEEK...UPPER RIDGE WILL BUILD BACK INTO THE
SOUTHERN PLAINS...THOUGH NOT TO THE STRENGTH IT DID IN JULY WHEN
WE WERE PLAGUED WITH PERSISTENT TRIPLE DIGIT TEMPERATURES.
STILL...MODEST RIDGING ALOFT WILL DIMINISH RAIN CHANCES AND LEAD
TO MORE SEASONABLE HIGH TEMPERATURES.
THE HURRICANE CENTER CONTINUES TO FORECAST TROPICAL STORM ISAAC
WILL TAKE A MORE EASTWARD PATH...ULTIMATELY MAKING LANDFALL
SOMEWHERE ALONG THE NORTHEAST GULF COAST. AS ISAAC REMAINS
SOMEWHAT DISORGANIZED...THE EXACT TRACK WILL BE VERY DIFFICULT
PINPOINT. THUS...IT REMAINS UNKNOWN IF ISAAC WILL HAVE ANY IMPACT
ALONG THE CENTRAL GULF COASTAL REGION OR ULTIMATELY THE SOUTHERN
PLAINS.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 91 69 86 72 / 20 40 50 60
HOBART OK 89 68 89 70 / 30 40 50 50
WICHITA FALLS TX 94 70 91 74 / 20 30 30 30
GAGE OK 89 68 90 69 / 40 50 50 60
PONCA CITY OK 92 69 85 71 / 10 50 50 60
DURANT OK 90 68 89 73 / 10 10 20 40
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
25/06
AREA FORECAST DISCUSSION
NWS NORMAN OK
645 AM CDT THU AUG 23 2012
.AVIATION...
SCATTERED SHRA/TSRA HAVE DEVELOPED EARLY THIS MORNING AS AN UPPER
DISTURBANCE MOVED INTO OKLAHOMA. THIS ACTIVITY WILL LIKELY LINGER
INTO THE EARLY AFTERNOON...WITH ISOLATED TSRA POSSIBLE INTO PARTS
OF NORTHERN AND CENTRAL OKLAHOMA BY LATE AFTERNOON. BRIEF MVFR
VSBYS WILL BE POSSIBLE WITH THESE STORMS...ESPECIALLY AT KCSM AND
KHBR...WITH LOWER PROBABILITIES AT KOKC...KOUN...AND KLAW. EXPECT
MORE WIDESPREAD SHRA WITH EMBEDDED TSRA ACROSS PORTIONS OF
NORTHERN AND WESTERN OKLAHOMA THIS EVENING AND
OVERNIGHT...SPREADING INTO CENTRAL OK BY 12Z FRIDAY. WILL INCLUDE
PROB30 GROUPS AT MOST SITES AS EXACT TIMING AND COVERAGE OF
SHRA/TSRA REMAINS IN QUESTION. OUTSIDE OF OCCASIONALSTORMS...GUSTY
SOUTH TO SOUTHWEST WINDS ARE EXPECTED THIS AFTERNOON THROUGH THIS
EVENING.
&&
.PREV DISCUSSION... /ISSUED 342 AM CDT THU AUG 23 2012/
DISCUSSION...
WIDESPREAD MID AND HIGH CLOUDS OVERSPREAD MUCH OF THE REGION AS A
WEAK UPPER DISTURBANCE MOVES SOUTHWARD THROUGH THE FLOW. AS THIS
CONTINUE TO MOVE SOUTHWARD ACROSS THE REGION...MODEST MID LEVEL
ASCENT MAY ALLOW FOR VERY ISOLATED SHOWERS AND PERHAPS A STORM OR
TWO. RECENT RUNS OF THE HRRR DEPICT A LARGE AREA OF SHOWER AND
THUNDERSTORM ACTIVITY DEVELOPING BY 10Z TO 11Z OVER WESTERN
OKLAHOMA AND NORTH TEXAS. CONFIDENCE IS LOW IN THIS SCENARIO AND
WILL MAINTAIN ONLY SLIGHT CHANCE POPS THROUGH 12Z THIS MORNING.
SHOWERS AND STORMS SHOULD DEVELOP THIS MORNING OVER WESTERN
OKLAHOMA AND PERSIST INTO TONIGHT...SPREADING EASTWARD WITH TIME.
EXPECT THE BEST CHANCES TO REMAIN OVER NORTHWEST OKLAHOMA. AS
SUCH...DAYTIME MAX TEMPS WILL BE A FEW DEGREES COOLER ACROSS
WESTERN OKLAHOMA AND WESTERN NORTH TEXAS.
THE FORECAST THROUGH THE WEEKEND REMAINS GENERALLY UNCHANGED AS
MODELS CONTINUE TO SUGGEST WIDESPREAD PRECIP WITH A SERIES OF
UPPER WAVES TRANSLATING EWD ACROSS THE SOUTHERN PLAINS. PERHAPS
THE MOST POTENT OF THESE WILL MOVE THROUGH TOMORROW AFTERNOON
THROUGH SUNDAY MORNING...GENERATING WIDESPREAD SHOWERS AND STORMS
ALONG WITH LOCALLY HEAVY RAINFALL. THE GREATEST RAINFALL TOTALS
WILL LIKELY REMAIN ACROSS NORTHERN OKLAHOMA NEAR THE KANSAS
OKLAHOMA BORDER. HERE...ISOLATED AREAS MAY SEE UP TO 2.5 TO 3
INCHES OF RAIN. ELSEWHERE...TOTAL RAINFALL ACCUMULATION WILL RANGE
FROM AROUND AN INCH TO 2 INCHES THROUGH THE WEEKEND. PERHAPS THE
ONLY MINOR CHANGE TO THE FORECAST IS IN THE TIMING OF A SFC FRONT
SET TO PUSH THROUGH THE REGION LATE THIS WEEKEND INTO EARLY NEXT
WEEK. RECENT GFS/EURO HAVE COME IN A BIT FASTER WITH FRONTAL
PASSAGE AND WILL NUDGE FRONTAL POSITION AND ASSOCIATED RAIN
CHANCES SOUTHEASTWARD THROUGH MONDAY. WITH MANY AREAS SEEING
PERSISTENT CLOUD COVER AND SHOWER ACTIVITY...HIGH TEMPS WILL
LIKELY BE SEVERAL DEGREES BELOW AVERAGE...WITH SOME LOCATIONS
REMAINING IN THE UPPER 70S FRIDAY INTO SATURDAY.
HEADING INTO NEXT WEEK...UPPER RIDGE WILL BUILD BACK INTO THE
SOUTHERN PLAINS...THOUGH NOT TO THE STRENGTH IT DID IN JULY WHEN
WE WERE PLAGUED WITH PERSISTENT TRIPLE DIGIT TEMPERATURES.
STILL...MODEST RIDGING ALOFT WILL DIMINISH RAIN CHANCES AND LEAD
TO MORE SEASONABLE HIGH TEMPERATURES.
THE HURRICANE CENTER CONTINUES TO FORECAST TROPICAL STORM ISAAC
WILL TAKE A MORE EASTWARD PATH...ULTIMATELY MAKING LANDFALL
SOMEWHERE ALONG THE NORTHEAST GULF COAST. AS ISAAC REMAINS
SOMEWHAT DISORGANIZED...THE EXACT TRACK WILL BE VERY DIFFICULT
PINPOINT. THUS...IT REMAINS UNKNOWN IF ISAAC WILL HAVE ANY IMPACT
ALONG THE CENTRAL GULF COASTAL REGION OR ULTIMATELY THE SOUTHERN
PLAINS.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 91 69 86 72 / 20 40 50 60
HOBART OK 91 68 89 70 / 30 40 50 50
WICHITA FALLS TX 94 70 91 74 / 20 30 30 30
GAGE OK 89 68 90 69 / 40 50 50 60
PONCA CITY OK 92 69 85 71 / 20 50 50 60
DURANT OK 93 68 89 73 / 10 10 20 40
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
30/84/84
AREA FORECAST DISCUSSION
NWS NORMAN OK
342 AM CDT THU AUG 23 2012
.DISCUSSION...
WIDESPREAD MID AND HIGH CLOUDS OVERSPREAD MUCH OF THE REGION AS A
WEAK UPPER DISTURBANCE MOVES SOUTHWARD THROUGH THE FLOW. AS THIS
CONTINUE TO MOVE SOUTHWARD ACROSS THE REGION...MODEST MID LEVEL
ASCENT MAY ALLOW FOR VERY ISOLATED SHOWERS AND PERHAPS A STORM OR
TWO. RECENT RUNS OF THE HRRR DEPICT A LARGE AREA OF SHOWER AND
THUNDERSTORM ACTIVITY DEVELOPING BY 10Z TO 11Z OVER WESTERN
OKLAHOMA AND NORTH TEXAS. CONFIDENCE IS LOW IN THIS SCENARIO AND
WILL MAINTAIN ONLY SLIGHT CHANCE POPS THROUGH 12Z THIS MORNING.
SHOWERS AND STORMS SHOULD DEVELOP THIS MORNING OVER WESTERN
OKLAHOMA AND PERSIST INTO TONIGHT...SPREADING EASTWARD WITH TIME.
EXPECT THE BEST CHANCES TO REMAIN OVER NORTHWEST OKLAHOMA. AS
SUCH...DAYTIME MAX TEMPS WILL BE A FEW DEGREES COOLER ACROSS
WESTERN OKLAHOMA AND WESTERN NORTH TEXAS.
THE FORECAST THROUGH THE WEEKEND REMAINS GENERALLY UNCHANGED AS
MODELS CONTINUE TO SUGGEST WIDESPREAD PRECIP WITH A SERIES OF
UPPER WAVES TRANSLATING EWD ACROSS THE SOUTHERN PLAINS. PERHAPS
THE MOST POTENT OF THESE WILL MOVE THROUGH TOMORROW AFTERNOON
THROUGH SUNDAY MORNING...GENERATING WIDESPREAD SHOWERS AND STORMS
ALONG WITH LOCALLY HEAVY RAINFALL. THE GREATEST RAINFALL TOTALS
WILL LIKELY REMAIN ACROSS NORTHERN OKLAHOMA NEAR THE KANSAS
OKLAHOMA BORDER. HERE...ISOLATED AREAS MAY SEE UP TO 2.5 TO 3
INCHES OF RAIN. ELSEWHERE...TOTAL RAINFALL ACCUMULATION WILL RANGE
FROM AROUND AN INCH TO 2 INCHES THROUGH THE WEEKEND. PERHAPS THE
ONLY MINOR CHANGE TO THE FORECAST IS IN THE TIMING OF A SFC FRONT
SET TO PUSH THROUGH THE REGION LATE THIS WEEKEND INTO EARLY NEXT
WEEK. RECENT GFS/EURO HAVE COME IN A BIT FASTER WITH FRONTAL
PASSAGE AND WILL NUDGE FRONTAL POSITION AND ASSOCIATED RAIN
CHANCES SOUTHEASTWARD THROUGH MONDAY. WITH MANY AREAS SEEING
PERSISTENT CLOUD COVER AND SHOWER ACTIVITY...HIGH TEMPS WILL
LIKELY BE SEVERAL DEGREES BELOW AVERAGE...WITH SOME LOCATIONS
REMAINING IN THE UPPER 70S FRIDAY INTO SATURDAY.
HEADING INTO NEXT WEEK...UPPER RIDGE WILL BUILD BACK INTO THE
SOUTHERN PLAINS...THOUGH NOT TO THE STRENGTH IT DID IN JULY WHEN
WE WERE PLAGUED WITH PERSISTENT TRIPLE DIGIT TEMPERATURES.
STILL...MODEST RIDGING ALOFT WILL DIMINISH RAIN CHANCES AND LEAD
TO MORE SEASONABLE HIGH TEMPERATURES.
THE HURRICANE CENTER CONTINUES TO FORECAST TROPICAL STORM ISAAC
WILL TAKE A MORE EASTWARD PATH...ULTIMATELY MAKING LANDFALL
SOMEWHERE ALONG THE NORTHEAST GULF COAST. AS ISAAC REMAINS
SOMEWHAT DISORGANIZED...THE EXACT TRACK WILL BE VERY DIFFICULT
PINPOINT. THUS...IT REMAINS UNKNOWN IF ISAAC WILL HAVE ANY IMPACT
ALONG THE CENTRAL GULF COASTAL REGION OR ULTIMATELY THE SOUTHERN
PLAINS.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 91 69 86 72 / 20 40 50 60
HOBART OK 91 68 89 70 / 30 40 50 50
WICHITA FALLS TX 94 70 91 74 / 20 30 30 30
GAGE OK 89 68 90 69 / 40 50 50 60
PONCA CITY OK 92 69 85 71 / 20 50 50 60
DURANT OK 93 68 89 73 / 10 10 20 40
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
30/AUSTIN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1244 PM CDT THU AUG 23 2012
.UPDATE...
SEE UPDATED AVIATION DISCUSSION BELOW FOR THE 18Z TAF ISSUANCE.
PRECIPITATION HAS PUSHED OFF TO THE EAST OF THE REGION...SO HAVE
REMOVED ALL POPS FROM THE FORECAST FOR TODAY. NO CHANGES MADE TO
WINDS OR TEMPERATURES AT THIS TIME.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH SATURDAY
SHOWERS AND THUNDERSTORMS CONTINUE TO MOVE EASTWARD ACROSS THE
EASTERN PORTION OF THE CWA...SCATTERED IN VARIETY. THINGS ARE
SHIFTING EAST WITH THE MOVEMENT OF THE LOW LEVEL JET. EXPECTING
THIS TREND TO CONTINUE OVER THE NEXT SEVERAL HOURS WITH ACTIVITY
PUSHING EAST INTO MN LATER THIS MORNING. ANY REDEVELOPMENT LATER
THIS AFTERNOON IS LOOKING LESS LIKELY OVER OUR AREA WITH THE FRONT
PUSHING EASTWARD AT A GOOD CLIP. EXPECT MOST ACTIVITY LATER TODAY
TO BE ACROSS MN INTO SOUTHEAST SD AND PORTIONS OF IA AND NE. ONE
THING TO WATCH THIS MORNING THOUGH IS ANOTHER WEAK DISTURBANCE OFF
TO THE WEST OVER WY. WATER VAPOR SHOWS THIS AND THERE IS AN ACCAS
FIELD ACROSS NORTHEAST WY AND SOUTHWEST SD. HRRR IS ACTUALLY
SHOWING A FEW SPOTTY SPRINKLES/LIGHT SHOWERS ADVANCING ACROSS
WESTERN AND CENTRAL SD THROUGH THE MORNING. FOR NOW HAVE NOT
INCLUDED ANYTHING IN THE FORECAST AS OBS TO THE WEST INDICATE VERY
HIGH CEILINGS. THIS WILL NEED TO BE WATCHED THOUGH FOR POTENTIAL
OF ISO SHOWERS OR SPRINKLES ACROSS THE SOUTHWEST CWA LATER THIS
MORNING.
OTHERWISE...WILL BE WATCHING NEXT SYSTEM FOR FRIDAY AND FRIDAY
NIGHT. FAIRLY POTENT SHORTWAVE WILL BE ADVANCING EASTWARD ACROSS
THE INTERNATIONAL BORDER. SHARP SFC COLD FRONT WILL ALSO BE
TRACKING ACROSS THE DAKOTAS. WEAK TO MODERATE INSTABILITY DEVELOPS
OVER THE AREA FRIDAY AFTERNOON AND EVENING...BUT IT APPEARS BEST
SYNOPTIC SCALE LIFT WILL BE ACROSS ND. EXPECTING A FEW SHOWERS AND
STORMS TO DEVELOP SO LEFT POPS IN CHANCE CATEGORY WITH THE
THINKING THAT BETTER AREAL COVERAGE WILL BE ACROSS ND.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
AN UPPER RIDGE WILL BUILD OVER THE WESTERN CONUS DURING THE
PERIOD...WITH A VERY GRADUAL/SLOW EASTWARD PROGRESSION. THE
RESULTING STABLE CONDITIONS AND THE REDEVELOPMENT OF AN ELEVATED
MIXED LAYER WITH H7 TEMPERATURES WARMING FROM AROUND +5C TO
UPWARDS OF +14C TRANSLATES INTO AN EXTENDED DRY PERIOD WITH
TEMPERATURE GRADUAL WARMING TO ABOVE NORMAL FOR THE FIRST HALF OF
NEXT WEEK.
&&
.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
DRY CONDITIONS EXPECTED TO PREVAIL AT THE LOCAL TAF SITES THE NEXT
24 HRS AS A WEAK AREA OF HIGH PRESSURE NOSES INTO THE REGION FROM
THE NORTHWEST. LIGHT WINDS THRU THE REMAINDER OF TODAY WILL SWITCH
TO THE SOUTH AND SOUTHEAST BY THE END OF THE TAF PERIOD. CLEAR TO
PARTLY CLOUDY SKIES WITH GENERALLY MID OR HIGH CLOUDS ANTICIPATED.
EXPECT VFR CONDITIONS TO PERSIST THE NEXT 24 HRS.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...PARKIN
SHORT TERM...TMT
LONG TERM...CONNELLY
AVIATION...VIPOND
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1020 AM CDT THU AUG 23 2012
.UPDATE...
PRECIPITATION HAS PUSHED OFF TO THE EAST OF THE REGION...SO HAVE
REMOVED ALL POPS FROM THE FORECAST FOR TODAY. NO CHANGES MADE TO
WINDS OR TEMPERATURES AT THIS TIME.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH SATURDAY
SHOWERS AND THUNDERSTORMS CONTINUE TO MOVE EASTWARD ACROSS THE
EASTERN PORTION OF THE CWA...SCATTERED IN VARIETY. THINGS ARE
SHIFTING EAST WITH THE MOVEMENT OF THE LOW LEVEL JET. EXPECTING
THIS TREND TO CONTINUE OVER THE NEXT SEVERAL HOURS WITH ACTIVITY
PUSHING EAST INTO MN LATER THIS MORNING. ANY REDEVELOPMENT LATER
THIS AFTERNOON IS LOOKING LESS LIKELY OVER OUR AREA WITH THE FRONT
PUSHING EASTWARD AT A GOOD CLIP. EXPECT MOST ACTIVITY LATER TODAY
TO BE ACROSS MN INTO SOUTHEAST SD AND PORTIONS OF IA AND NE. ONE
THING TO WATCH THIS MORNING THOUGH IS ANOTHER WEAK DISTURBANCE OFF
TO THE WEST OVER WY. WATER VAPOR SHOWS THIS AND THERE IS AN ACCAS
FIELD ACROSS NORTHEAST WY AND SOUTHWEST SD. HRRR IS ACTUALLY
SHOWING A FEW SPOTTY SPRINKLES/LIGHT SHOWERS ADVANCING ACROSS
WESTERN AND CENTRAL SD THROUGH THE MORNING. FOR NOW HAVE NOT
INCLUDED ANYTHING IN THE FORECAST AS OBS TO THE WEST INDICATE VERY
HIGH CEILINGS. THIS WILL NEED TO BE WATCHED THOUGH FOR POTENTIAL
OF ISO SHOWERS OR SPRINKLES ACROSS THE SOUTHWEST CWA LATER THIS
MORNING.
OTHERWISE...WILL BE WATCHING NEXT SYSTEM FOR FRIDAY AND FRIDAY
NIGHT. FAIRLY POTENT SHORTWAVE WILL BE ADVANCING EASTWARD ACROSS
THE INTERNATIONAL BORDER. SHARP SFC COLD FRONT WILL ALSO BE
TRACKING ACROSS THE DAKOTAS. WEAK TO MODERATE INSTABILITY DEVELOPS
OVER THE AREA FRIDAY AFTERNOON AND EVENING...BUT IT APPEARS BEST
SYNOPTIC SCALE LIFT WILL BE ACROSS ND. EXPECTING A FEW SHOWERS AND
STORMS TO DEVELOP SO LEFT POPS IN CHANCE CATEGORY WITH THE
THINKING THAT BETTER AREAL COVERAGE WILL BE ACROSS ND.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
AN UPPER RIDGE WILL BUILD OVER THE WESTERN CONUS DURING THE
PERIOD...WITH A VERY GRADUAL/SLOW EASTWARD PROGRESSION. THE
RESULTING STABLE CONDITIONS AND THE REDEVELOPMENT OF AN ELEVATED
MIXED LAYER WITH H7 TEMPERATURES WARMING FROM AROUND +5C TO
UPWARDS OF +14C TRANSLATES INTO AN EXTENDED DRY PERIOD WITH
TEMPERATURE GRADUAL WARMING TO ABOVE NORMAL FOR THE FIRST HALF OF
NEXT WEEK.
&&
.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
A FEW LIGHT SHOWERS AND POSSIBLY A RUMBLE OF THUNDER REMAIN AROUND
THE KATY TERMINAL WITH THE TAF ISSUANCE...HOWEVER THESE WILL
CONTINUE TO PROCEED EAST WITH LIMITED COVERAGE/INTENSITY. WINDS
OUT OF THE NORTH WILL SHIFT AROUND TO SOUTHERLY TONIGHT. VFR
CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...PARKIN
SHORT TERM...TMT
LONG TERM...CONNELLY
AVIATION...CONNELLY
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
625 AM CDT THU AUG 23 2012
.UPDATE...
SEE UPDATED AVIATION DISCUSSION BELOW.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH SATURDAY
SHOWERS AND THUNDERSTORMS CONTINUE TO MOVE EASTWARD ACROSS THE
EASTERN PORTION OF THE CWA...SCATTERED IN VARIETY. THINGS ARE
SHIFTING EAST WITH THE MOVEMENT OF THE LOW LEVEL JET. EXPECTING
THIS TREND TO CONTINUE OVER THE NEXT SEVERAL HOURS WITH ACTIVITY
PUSHING EAST INTO MN LATER THIS MORNING. ANY REDEVELOPMENT LATER
THIS AFTERNOON IS LOOKING LESS LIKELY OVER OUR AREA WITH THE FRONT
PUSHING EASTWARD AT A GOOD CLIP. EXPECT MOST ACTIVITY LATER TODAY
TO BE ACROSS MN INTO SOUTHEAST SD AND PORTIONS OF IA AND NE. ONE
THING TO WATCH THIS MORNING THOUGH IS ANOTHER WEAK DISTURBANCE OFF
TO THE WEST OVER WY. WATER VAPOR SHOWS THIS AND THERE IS AN ACCAS
FIELD ACROSS NORTHEAST WY AND SOUTHWEST SD. HRRR IS ACTUALLY
SHOWING A FEW SPOTTY SPRINKLES/LIGHT SHOWERS ADVANCING ACROSS
WESTERN AND CENTRAL SD THROUGH THE MORNING. FOR NOW HAVE NOT
INCLUDED ANYTHING IN THE FORECAST AS OBS TO THE WEST INDICATE VERY
HIGH CEILINGS. THIS WILL NEED TO BE WATCHED THOUGH FOR POTENTIAL
OF ISO SHOWERS OR SPRINKLES ACROSS THE SOUTHWEST CWA LATER THIS
MORNING.
OTHERWISE...WILL BE WATCHING NEXT SYSTEM FOR FRIDAY AND FRIDAY
NIGHT. FAIRLY POTENT SHORTWAVE WILL BE ADVANCING EASTWARD ACROSS
THE INTERNATIONAL BORDER. SHARP SFC COLD FRONT WILL ALSO BE
TRACKING ACROSS THE DAKOTAS. WEAK TO MODERATE INSTABILITY DEVELOPS
OVER THE AREA FRIDAY AFTERNOON AND EVENING...BUT IT APPEARS BEST
SYNOPTIC SCALE LIFT WILL BE ACROSS ND. EXPECTING A FEW SHOWERS AND
STORMS TO DEVELOP SO LEFT POPS IN CHANCE CATEGORY WITH THE
THINKING THAT BETTER AREAL COVERAGE WILL BE ACROSS ND.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
AN UPPER RIDGE WILL BUILD OVER THE WESTERN CONUS DURING THE
PERIOD...WITH A VERY GRADUAL/SLOW EASTWARD PROGRESSION. THE
RESULTING STABLE CONDITIONS AND THE REDEVELOPMENT OF AN ELEVATED
MIXED LAYER WITH H7 TEMPERATURES WARMING FROM AROUND +5C TO
UPWARDS OF +14C TRANSLATES INTO AN EXTENDED DRY PERIOD WITH
TEMPERATURE GRADUAL WARMING TO ABOVE NORMAL FOR THE FIRST HALF OF
NEXT WEEK.
&&
.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
A FEW LIGHT SHOWERS AND POSSIBLY A RUMBLE OF THUNDER REMAIN AROUND
THE KATY TERMINAL WITH THE TAF ISSUANCE...HOWEVER THESE WILL
CONTINUE TO PROCEED EAST WITH LIMITED COVERAGE/INTENSITY. WINDS
OUT OF THE NORTH WILL SHIFT AROUND TO SOUTHERLY TONIGHT. VFR
CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...CONNELLY
SHORT TERM...TMT
LONG TERM...CONNELLY
AVIATION...CONNELLY
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
407 AM CDT THU AUG 23 2012
.SHORT TERM...TODAY THROUGH SATURDAY
SHOWERS AND THUNDERSTORMS CONTINUE TO MOVE EASTWARD ACROSS THE
EASTERN PORTION OF THE CWA...SCATTERED IN VARIETY. THINGS ARE
SHIFTING EAST WITH THE MOVEMENT OF THE LOW LEVEL JET. EXPECTING
THIS TREND TO CONTINUE OVER THE NEXT SEVERAL HOURS WITH ACTIVITY
PUSHING EAST INTO MN LATER THIS MORNING. ANY REDEVELOPMENT LATER
THIS AFTERNOON IS LOOKING LESS LIKELY OVER OUR AREA WITH THE FRONT
PUSHING EASTWARD AT A GOOD CLIP. EXPECT MOST ACTIVITY LATER TODAY
TO BE ACROSS MN INTO SOUTHEAST SD AND PORTIONS OF IA AND NE. ONE
THING TO WATCH THIS MORNING THOUGH IS ANOTHER WEAK DISTURBANCE OFF
TO THE WEST OVER WY. WATER VAPOR SHOWS THIS AND THERE IS AN ACCAS
FIELD ACROSS NORTHEAST WY AND SOUTHWEST SD. HRRR IS ACTUALLY
SHOWING A FEW SPOTTY SPRINKLES/LIGHT SHOWERS ADVANCING ACROSS
WESTERN AND CENTRAL SD THROUGH THE MORNING. FOR NOW HAVE NOT
INCLUDED ANYTHING IN THE FORECAST AS OBS TO THE WEST INDICATE VERY
HIGH CEILINGS. THIS WILL NEED TO BE WATCHED THOUGH FOR POTENTIAL
OF ISO SHOWERS OR SPRINKLES ACROSS THE SOUTHWEST CWA LATER THIS
MORNING.
OTHERWISE...WILL BE WATCHING NEXT SYSTEM FOR FRIDAY AND FRIDAY
NIGHT. FAIRLY POTENT SHORTWAVE WILL BE ADVANCING EASTWARD ACROSS
THE INTERNATIONAL BORDER. SHARP SFC COLD FRONT WILL ALSO BE
TRACKING ACROSS THE DAKOTAS. WEAK TO MODERATE INSTABILITY DEVELOPS
OVER THE AREA FRIDAY AFTERNOON AND EVENING...BUT IT APPEARS BEST
SYNOPTIC SCALE LIFT WILL BE ACROSS ND. EXPECTING A FEW SHOWERS AND
STORMS TO DEVELOP SO LEFT POPS IN CHANCE CATEGORY WITH THE
THINKING THAT BETTER AREAL COVERAGE WILL BE ACROSS ND.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
AN UPPER RIDGE WILL BUILD OVER THE WESTERN CONUS DURING THE
PERIOD...WITH A VERY GRADUAL/SLOW EASTWARD PROGRESSION. THE
RESULTING STABLE CONDITIONS AND THE REDEVELOPMENT OF AN ELEVATED
MIXED LAYER WITH H7 TEMPERATURES WARMING FROM AROUND +5C TO
UPWARDS OF +14C TRANSLATES INTO AN EXTENDED DRY PERIOD WITH
TEMPERATURE GRADUAL WARMING TO ABOVE NORMAL FOR THE FIRST HALF OF
NEXT WEEK.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
VFR CONDITIONS WILL PREVAIL ACROSS THE AREA THROUGH THURSDAY
EVENING. SHOWERS AND THUNDERSTORMS WILL CONTINUE TO MOVE EAST
DURING THE OVERNIGHT HOURS. AT THIS TIME...HAVE NOT INTRODUCED
CIGS OR VSBYS BELOW VFR LEVELS...THOUGH IT IS POSSIBLE WITH ANY
THUNDERSTORMS THAT DEVELOP. THE MOST LIKELY SITE TO SEE THE
REDUCTIONS IN CIGS AND VSBYS WILL BE KATY...MAINLY BETWEEN 06Z AND
10Z.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
SHORT TERM...TMT
LONG TERM...CONNELLY
AVIATION...CONNELLY
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
556 PM CDT THU AUG 23 2012
.AVIATION...
A MCV CAN BE SEEN ON VISIBLE IMAGERY THIS AFTERNOON OVER THE
SOUTHERN TEXAS PANHANDLE. A SMALL THUNDERSTORM CLUSTER HAS
DEVELOPED AHEAD OF THE FEATURE BETWEEN PADUCAH AND ASPERMONT
TX...AND IS MOVING SLOWLY EAST. ACTIVITY MAY AFFECT A FEW OF THE
WESTERN COUNTIES BEFORE DISSIPATING LATER THIS EVENING...BUT AT
THIS TIME IT IS EXPECTED TO REMAIN WELL WEST AND NORTHWEST OF TAF
SITES.
AT THE SURFACE...SOUTHEAST WINDS SHOULD REMAIN UP AROUND 8-10 KT
THIS EVENING AND OVERNIGHT IN RESPONSE TO A DEEPENING SURFACE LOW
IN LEE OF THE ROCKIES. WINDS WILL INCREASE INTO THE 10-15KT RANGE
AROUND MIDDAY FRIDAY. CONVECTION IS EXPECTED TO REMAIN NORTHWEST
OF THE NORTH TEXAS TERMINALS THROUGH THE MAJORITY OF THIS
FORECAST CYCLE. STORMS MAY BEGIN TO ENCROACH ON THE METROPLEX
FRIDAY EVENING AFTER 00Z BUT AT THIS TIME CONFIDENCE IS TOO LOW TO
INCLUDE IN THE EXTENDED DFW TAF.
30
&&
.PREV DISCUSSION... /ISSUED 302 PM CDT THU AUG 23 2012/
CONVECTION FROM CHILDRESS TO SNYDER REMAINS WELL ELEVATED...WITH
BASES AOA 10KFT AGL. AS THE ACTIVITY MOVES EAST...IT WILL ENTER
AN AREA OF DEEPER MID-LEVEL MOISTURE. AS THE STORMS INGEST THIS
AIR...THE DCAPE (IN A LAGRANGIAN SENSE) WILL DIMINISH
CONSIDERABLY...AND THE THREAT OF DOWNBURST WINDS WILL BE
NEGLIGIBLE...DESPITE THE HIGH BASES. WITH WEAK SHEAR AND MOIST
ADIABATIC LAPSE RATES ALOFT...THE CONVECTION IS UNLIKELY TO
INTENSIFY...BUT IT MAY HOLD TOGETHER LONG ENOUGH TO REACH FAR
WESTERN ZONES LATE THIS AFTERNOON OR EARLY EVENING BEFORE
DISSIPATING. THE CU FIELD JUST WEST OF THE CWA IS BASED AROUND
5KFT AND APPEARS TO BE CAPPED...BUT WITH ANY FORCING ABOVE
800MB...THE MINIMAL INHIBITION CURRENTLY IN PLACE SHOULD BE ERODED
SUFFICIENTLY TO ALLOW SOME CELLS TO BECOME SURFACE-BASED.
REGARDLESS...THE BOUNDARY-LAYER INSTABILITY IS UNIMPRESSIVE...AND
ENTRAINING THIS SURFACE AIR WOULD ONLY FURTHER DECREASE THE
DOWNBURST THREAT.
SEA BREEZE CONVECTION IS CURRENTLY CONFINED TO THE HOUSTON METRO
AREA. AS SUCH...CONFIDENCE IS DIMINISHING FURTHER IN THE POTENTIAL
FOR ANY PROPAGATING OUTFLOW BOUNDARIES REACHING THE CWA. AS WITH
PREVIOUS RUNS...THE 18Z RUC MAINTAINS SOME CONVECTIVE CELLS IN FAR
SOUTHEAST ZONES...WHERE THE PROFILE WILL BECOME INCREASINGLY
TROPICAL. WITH DEEPENING MOISTURE AND DIMINISHING SUBSIDENCE...
WILL CONTINUE TO CARRY SOME ISOLATED MENTION IN THE SOUTHEAST.
LAS VEGAS HAD TALLIED ONLY 1.53 INCHES OF PRECIP IN 11 MONTHS
BEFORE RECEIVING A DELUGE OF 1.65 INCHES ON WEDNESDAY. (THIS
EASILY BROKE THE DAILY RECORD OF 0.23 INCHES.) THE OFFENDING
SHORTWAVE CONTINUES TO DEEPEN OVER THE FOUR CORNERS...WITH
WIDESPREAD CONVECTION DOWNSTREAM ACROSS NEW MEXICO AND COLORADO.
AS THE SYSTEM REACHES THE TEXAS PANHANDLE...IT WILL BE IN PHASE
WITH THE CYCLONE NEAR THE CANADIAN BORDER. AS A RESULT...THE
FEATURE WILL LIKELY SHEAR AND BE DRAWN NORTHWARD. WITH THE ENERGY
FARTHER NORTH...THE PRECIPITATION CHANCES FOR NORTH TEXAS THIS
WEEKEND WOULD BE REDUCED. WILL MAINTAIN BEST CHANCES GENERALLY
ALONG THE RED RIVER VALLEY. DESPITE THE LIKELY EVOLUTION OF THE
CONVECTIVE EVENT...EXTENDED GUIDANCE IS STILL FAVORING A RESULTING
EROSION OF THE RIDGE ABOVE NORTH TEXAS.
THE SHORTWAVE (AND MUCH LARGER CYCLONE) WILL ALLOW MILDER AIR TO
INVADE THE CENTRAL PLAINS. BUT WITH NEAR NORMAL TEMPERATURES
EXPECTED WITH THE SURFACE ANTICYCLONE...IT WOULD SUGGEST A
TENDENCY FOR THE ASSOCIATED FRONTAL BOUNDARY TO FAIL TO PENETRATE
THE SOUTHERN PLAINS. BUT IF THE RIDGE DOES ERODE ENOUGH TO ALLOW
FOR NORTHERLY FLOW...THE BOUNDARY COULD CERTAINLY REACH NORTH
TEXAS. EVEN THE ECMWF...WHICH PROJECTS A MID-LEVEL RIDGE AXIS FROM
TEXAS INTO THE PRAIRIE PROVINCES EARLY NEXT WEEK...ALLOWS
NORTHERLY SURFACE FLOW TO SLIDE DOWN THE MISSISSIPPI VALLEY AND
BACKDOOR INTO NORTH TEXAS...INDUCED BY THE PROXIMITY OF ISAAC.
(THE LATEST ECMWF RUN TAKES ISAAC INTO DFW...BUT THE EURO WAS
ALREADY A FAR WESTERN OUTLIER...SO DO NOT HAVE MUCH CONFIDENCE IN
THIS LATEST SOLUTION.) EXPECT A WARMING TREND NEXT WEEK...DESPITE
ANY LIGHT NORTH WINDS. WHATEVER TRACK ISAAC TAKES...NORTH TEXAS
WOULD LIKELY BE IN A SUBSIDENT ZONE. A MORE EASTERLY TRACK WOULD
ALLOW THE PLAINS RIDGE TO INTENSIFY...WHILE A MORE WESTERLY TRACK
COULD PUT EAST TEXAS WITHIN THE RING OF STRONG DOWNWARD MOTION
AROUND THE PERIPHERY OF THE CIRRUS SHIELD. TEMPERATURES MAY REACH
THE UPPER 90S BY DAY 7 (THURSDAY AUGUST 30).
25
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 76 93 76 94 77 / 5 10 20 20 20
WACO, TX 74 94 75 94 76 / 5 10 10 10 10
PARIS, TX 70 91 71 91 73 / 5 20 30 50 20
DENTON, TX 73 93 75 94 76 / 5 10 20 20 20
MCKINNEY, TX 70 91 73 91 75 / 5 20 20 30 20
DALLAS, TX 75 91 76 94 77 / 5 10 20 20 20
TERRELL, TX 72 91 73 92 75 / 5 20 20 20 20
CORSICANA, TX 73 92 73 93 75 / 5 10 20 20 10
TEMPLE, TX 73 94 73 94 74 / 10 10 10 10 10
MINERAL WELLS, TX 72 94 72 94 73 / 10 10 20 20 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
30/
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
302 PM CDT THU AUG 23 2012
.DISCUSSION...
CONVECTION FROM CHILDRESS TO SNYDER REMAINS WELL ELEVATED...WITH
BASES AOA 10KFT AGL. AS THE ACTIVITY MOVES EAST...IT WILL ENTER
AN AREA OF DEEPER MID-LEVEL MOISTURE. AS THE STORMS INGEST THIS
AIR...THE DCAPE (IN A LAGRANGIAN SENSE) WILL DIMINISH
CONSIDERABLY...AND THE THREAT OF DOWNBURST WINDS WILL BE
NEGLIGIBLE...DESPITE THE HIGH BASES. WITH WEAK SHEAR AND MOIST
ADIABATIC LAPSE RATES ALOFT...THE CONVECTION IS UNLIKELY TO
INTENSIFY...BUT IT MAY HOLD TOGETHER LONG ENOUGH TO REACH FAR
WESTERN ZONES LATE THIS AFTERNOON OR EARLY EVENING BEFORE
DISSIPATING. THE CU FIELD JUST WEST OF THE CWA IS BASED AROUND
5KFT AND APPEARS TO BE CAPPED...BUT WITH ANY FORCING ABOVE
800MB...THE MINIMAL INHIBITION CURRENTLY IN PLACE SHOULD BE ERODED
SUFFICIENTLY TO ALLOW SOME CELLS TO BECOME SURFACE-BASED.
REGARDLESS...THE BOUNDARY-LAYER INSTABILITY IS UNIMPRESSIVE...AND
ENTRAINING THIS SURFACE AIR WOULD ONLY FURTHER DECREASE THE
DOWNBURST THREAT.
SEA BREEZE CONVECTION IS CURRENTLY CONFINED TO THE HOUSTON METRO
AREA. AS SUCH...CONFIDENCE IS DIMINISHING FURTHER IN THE POTENTIAL
FOR ANY PROPAGATING OUTFLOW BOUNDARIES REACHING THE CWA. AS WITH
PREVIOUS RUNS...THE 18Z RUC MAINTAINS SOME CONVECTIVE CELLS IN FAR
SOUTHEAST ZONES...WHERE THE PROFILE WILL BECOME INCREASINGLY
TROPICAL. WITH DEEPENING MOISTURE AND DIMINISHING SUBSIDENCE...
WILL CONTINUE TO CARRY SOME ISOLATED MENTION IN THE SOUTHEAST.
LAS VEGAS HAD TALLIED ONLY 1.53 INCHES OF PRECIP IN 11 MONTHS
BEFORE RECEIVING A DELUGE OF 1.65 INCHES ON WEDNESDAY. (THIS
EASILY BROKE THE DAILY RECORD OF 0.23 INCHES.) THE OFFENDING
SHORTWAVE CONTINUES TO DEEPEN OVER THE FOUR CORNERS...WITH
WIDESPREAD CONVECTION DOWNSTREAM ACROSS NEW MEXICO AND COLORADO.
AS THE SYSTEM REACHES THE TEXAS PANHANDLE...IT WILL BE IN PHASE
WITH THE CYCLONE NEAR THE CANADIAN BORDER. AS A RESULT...THE
FEATURE WILL LIKELY SHEAR AND BE DRAWN NORTHWARD. WITH THE ENERGY
FARTHER NORTH...THE PRECIPITATION CHANCES FOR NORTH TEXAS THIS
WEEKEND WOULD BE REDUCED. WILL MAINTAIN BEST CHANCES GENERALLY
ALONG THE RED RIVER VALLEY. DESPITE THE LIKELY EVOLUTION OF THE
CONVECTIVE EVENT...EXTENDED GUIDANCE IS STILL FAVORING A RESULTING
EROSION OF THE RIDGE ABOVE NORTH TEXAS.
THE SHORTWAVE (AND MUCH LARGER CYCLONE) WILL ALLOW MILDER AIR TO
INVADE THE CENTRAL PLAINS. BUT WITH NEAR NORMAL TEMPERATURES
EXPECTED WITH THE SURFACE ANTICYCLONE...IT WOULD SUGGEST A
TENDENCY FOR THE ASSOCIATED FRONTAL BOUNDARY TO FAIL TO PENETRATE
THE SOUTHERN PLAINS. BUT IF THE RIDGE DOES ERODE ENOUGH TO ALLOW
FOR NORTHERLY FLOW...THE BOUNDARY COULD CERTAINLY REACH NORTH
TEXAS. EVEN THE ECMWF...WHICH PROJECTS A MID-LEVEL RIDGE AXIS FROM
TEXAS INTO THE PRAIRIE PROVINCES EARLY NEXT WEEK...ALLOWS
NORTHERLY SURFACE FLOW TO SLIDE DOWN THE MISSISSIPPI VALLEY AND
BACKDOOR INTO NORTH TEXAS...INDUCED BY THE PROXIMITY OF ISAAC.
(THE LATEST ECMWF RUN TAKES ISAAC INTO DFW...BUT THE EURO WAS
ALREADY A FAR WESTERN OUTLIER...SO DO NOT HAVE MUCH CONFIDENCE IN
THIS LATEST SOLUTION.) EXPECT A WARMING TREND NEXT WEEK...DESPITE
ANY LIGHT NORTH WINDS. WHATEVER TRACK ISAAC TAKES...NORTH TEXAS
WOULD LIKELY BE IN A SUBSIDENT ZONE. A MORE EASTERLY TRACK WOULD
ALLOW THE PLAINS RIDGE TO INTENSIFY...WHILE A MORE WESTERLY TRACK
COULD PUT EAST TEXAS WITHIN THE RING OF STRONG DOWNWARD MOTION
AROUND THE PERIPHERY OF THE CIRRUS SHIELD. TEMPERATURES MAY REACH
THE UPPER 90S BY DAY 7 (THURSDAY AUGUST 30).
25
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 91 76 93 76 94 / 5 5 10 20 20
WACO, TX 91 74 94 75 94 / 5 5 10 10 10
PARIS, TX 92 70 91 71 91 / 5 5 20 30 50
DENTON, TX 91 73 93 75 94 / 10 5 10 20 20
MCKINNEY, TX 92 70 91 73 91 / 5 5 20 20 30
DALLAS, TX 91 75 91 76 94 / 5 5 10 20 20
TERRELL, TX 92 72 91 73 92 / 5 5 20 20 20
CORSICANA, TX 92 73 92 73 93 / 5 5 10 20 20
TEMPLE, TX 91 73 94 73 94 / 10 10 10 10 10
MINERAL WELLS, TX 91 72 94 72 94 / 10 10 10 20 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
05/25
AREA FORECAST DISCUSSION...UPDATED
NWS AMARILLO TX
1252 PM CDT THU AUG 23 2012
.AVIATION...
12Z SOUNDING FROM KAMA REVEALS THAT EARLY MORNING ATMOSPHERE HAD
BECOME MORE UNSTABLE DURING PAST 24 HOURS...WITH STEEPER MID-LEVEL
LAPSE RATE AND GREATER AMOUNT OF LOW-LEVEL MOISTURE IN PLACE. WITH
ADDITIONAL INSOLATION TO OCCUR THIS AFTERNOON...EXPECT SCATTERED
THUNDERSTORMS TO DEVELOP AROUND 21Z...AS MODEST MID-LEVEL SUPPORT
ARRIVES IN THE FORM OF VORTICITY MAXIMUM BEING EJECTED FROM 700 MB
TROF. EXPECT THAT DEVELOPMENT WILL OCCUR WEST OF TERMINALS NEAR
SURFACE TROF RUNNING THROUGH WESTERN PARTS OF FORECAST AREA.
SCATTERED THUNDERSTORMS EXPECTED TO CONTINUE THROUGH THE EVENING AS
HEALTHY LOW-LEVEL JET DEVELOPS. HAVE NOT INCLUDED MENTION OF THUNDER
AT KAMA AT THIS TIME...BUT WILL MONITOR CLOSELY AT AMEND IF
CONVECTION BECOMES A MORE REALISTIC THREAT AND WHEN TIMING OF SUCH
CAN BE BE ASCERTAINED. APART FROM BRIEF VISIBILITY REDUCTIONS IN
SCATTERED THUNDERSTORMS...VFR FORECAST CONTINUES NEXT 24 HOURS.
COCKRELL
&&
.PREV DISCUSSION... /ISSUED 637 AM CDT THU AUG 23 2012/
AVIATION...
FOR THE 12Z TAFS...VFR CONDITIONS ARE EXPECTED OUTSIDE OF TSRA.
PRIMARY CONCERN IS POTENTIAL FOR TSRA THIS AFTERNOON AND EVENING.
HIGHEST POTENTIAL APPEARS TO BE AT KDHT AND KGUY. DELAYED START OF
VCTS AT KDHT TO 01Z-05Z AND INSERTED VCTS REMARKS AT KGUY 23Z-04Z.
HAVE SOMEWHAT LOW CONFIDENCE ON TIMING. THERE IS A POSSIBILITY KAMA
COULD BE IMPACTED 23Z-03Z...BUT CONFIDENCE IS TOO LOW TO MENTION VCTS
AT THIS TIME. BRIEF IFR CONDITIONS WILL BE POSSIBLE IF TSRA DIRECTLY
IMPACTS A TERMINAL.
JACKSON
PREV DISCUSSION... /ISSUED 437 AM CDT THU AUG 23 2012/
DISCUSSION...
THE GOING THINKING FOR THE FCST PACKAGE REMAINS PRETTY SIMILAR TO
PREVIOUS SHIFTS WITH A GENERALLY UNSETTLED PATTERN TO PREVAIL
THROUGH THE WEEKEND. IT DOES HOWEVER REMAIN DIFFICULT TO PIN DOWN
THE MOST LIKELY PERIODS FOR SHOWERS AND STORMS AS OVERALL FORCING
REMAINS PRETTY WEAK...AND SHRTWV ENERGY IS NOT BEING HANDLED WELL IN
THE MODELS. WHILE PARTS IF NOT MOST OF THE PANHANDLES SHOULD GET AT
LEAST SOME RAIN OVER THE NEXT 3 DAYS...MODEL DISCREPANCIES MAKE THIS
A LOW CONFIDENCE FCST. IT LOOKS LIKE THE FAVORED AREA FOR PRECIP MORE
OFTEN THAN NOT IS GOING TO BE THE ERN HALF OF THE CWA. WHILE ISOLATED
PULSE OR MULTICELL SVR WX MAY BE NOTED THE NEXT 3 AFTERNOONS...
WIDESPREAD SVR WX IS NOT EXPECTED DUE TO GENERALLY LIMITED SHEAR.
TODAY...
AS HAS BEEN THE CASE RECENTLY...MODEL PROGGED INSTABILITY VARIES
GREATLY AGAIN THIS AFTERNOON WITH ANYWHERE FROM NAM DEPICTED 700
J/KG TO RUC DEPICTED 2500 J/KG MLCAPE FCST THIS AFTERNOON. SOME OF
THE AFTERNOON INSTABILITY WILL HINGE ON THE EXTENT OF MID AND HIGH
CLOUDS...WHICH LOOK TO BE OVERDONE IN THE NAM. THEREFORE...SIMILAR
TO THIS PAST MON...WILL SIDE WITH THE SREF...WHICH SHOWS A GOOD
COMPROMISE CLOSER TO THE RUC WITH ABOUT 2000 J/KG MLCAPE BY LATER
THIS AFTERNOON. WHAT THE MODELS DO AGREE ON IS THAT INHIBITION
SHOULD BE WEAK THIS AFTERNOON. SO...IN SPITE OF ONLY WEAK SYNOPTIC
FORCING DUE TO A VERY WEAK SHRTWV...HAVE DECIDED TO INCREASE PRECIP
CHCS THIS AFTERNOON GIVEN THE PREFERENCE TOWARD HIGHER INSTABILITY.
ISOLATED STRONG TO SVR STORMS WILL BE POSSIBLE WITH LARGE HAIL AND
DAMAGING WINDS THE MAIN THREATS. THE SVR THREAT SHOULD DIMINISH AS
WE HEAD INTO THE NIGHTTIME HRS.
TONIGHT...
TONIGHT/S PD HAS BECOME QUITE TRICKY AS OVERNIGHT PRECIP CHCS WILL
BE SOMEWHAT MODULATED BY AFTERNOON CONVECTION /OR LACK THEREOF/. HAVE
LEFT GOING 40 PERCENT POPS...BUT THE THINKING IS THAT THE BEST CHCS
MAY BE BEFORE MIDNIGHT. IN SPITE OF AN INCREASING LLJ...IT APPEARS
THE AREA WILL BE UNDER THE INFLUENCE OF WEAK UPR SUBSIDENCE IN THE
WAKE OF THE AFTERNOON SHRTWV.
FRIDAY AND FRIDAY NIGHT...
AGAIN...CONFIDENCE AND TIMING OF SHRTWV RIPPLES OF ENERGY MAKE THESE
PDS TOUGH TO PIN DOWN...BUT AMPLE MSTR SHOULD AGAIN PROMOTE AT LEAST
CHCS FOR PRECIP. IT APPEARS THE BEST CHC MAY LIE WITH AFTERNOON
CONVECTION FRI AFTERNOON AND EVENING...BUT A MODEST LLJ COULD ALSO
PROMOTE PRECIP FRI NIGHT. AGAIN...DEPENDING ON INSTABILITY...SOME
SVR WX COULD BE NOTED FRI AFTERNOON.
SATURDAY THROUGH SUNDAY...
IF CURRENT MODEL PROGS HOLD...SAT AFTERNOON SHOULD BE A FAVORED
PERIOD FOR SHOWERS AND STORMS AS A FINAL...AND LIKELY STRONGER
SHRTWV TROUGH KICKS THROUGH THE AREA. HAVE LEFT SLIGHT CHCS FOR POPS
GOING FOR SUN...BUT PRECIP POTENTIAL DOES NOT LOOK ALL THAT
IMPRESSIVE ON SUN.
MONDAY ONWARD...
DISCREPANCY EXISTS IN MED RANGE MODELS WITH PLACEMENT AND STRENGTH
OF A REBUILDING UPR RIDGE OVER THE ERN ROCKIES/HIGH PLAINS...WITH
MUCH OF THE UNCERTAINTY DUE TO QUESTIONS ABOUT THE TRACK OF ISAAC
AND IT/S AFFECT ON THE UPR PATTERN. MOST SIGNS DO POINT TO A DRY AND
WARM PD FROM MON THROUGH MUCH OF THE NEXT WORK WEEK.
HEAVY RAIN THREAT...
WITH PWATS ABOVE 1.5 INCHES FOR A GOOD PART OF THE NEXT 3 DAYS...
DEEP WARM CLOUD LAYERS AOA 10KFT...TALL CAPE PROFILES...AND FAIRLY
SLOW STORM MOTIONS...SHOWERS AND STORMS STAND TO BE EFFICIENT PRECIP
PRODUCERS. HOWEVER...A LACK OF LOW LVL FOCUSING BNDRYS MAY KEEP
TRAINING TSTORMS TO A RELATIVE MINIMUM...KEEPING ANY FLASH FLOODING
ISOLATED.
TEMPERATURE-WISE...
HIGHS WILL GENERALLY BE NEAR TO SLIGHTLY ABOVE NORMAL THROUGH THE
WEEKEND...PUSHING A LITTLE FURTHER ABOVE NORMAL BY NEXT WEEK. LOWS
WILL BE ABOVE NORMAL THROUGH THE PD.
SIMPSON
FIRE WEATHER...
NEITHER ELEVATED NOR CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED
THROUGH THE NEXT SEVERAL DAYS...THOUGH BREEZY SOUTHERLY WINDS WILL BE
NOTED THROUGH SATURDAY.
SIMPSON
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
03/16
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1219 PM CDT THU AUG 23 2012
.DISCUSSION...
SEE AVIATION DISCUSSION BELOW...
&&
.AVIATION...
ISOLATED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THIS
AFTERNOON ACROSS MUCH OF THE AREA...WITH THE BEST CHANCE AT KABI
AND KSJT. COVERAGE IS EXPECTED TO REMAIN ISOLATED...SO FOR NOW I
HAVE LEFT ANY MENTION OF THUNDER OUT OF THE TAFS. SOUTH WINDS OF
10 TO 15 KNOTS THIS AFTERNOON...WILL BECOME LIGHT AND VARIABLE
AROUND 00Z. PATCHY STRATUS DEVELOPMENT IS POSSIBLE...MAINLY OVER
THE NORTHWEST HILL COUNTRY...AFTER 10Z. BRIEF MVFR CONDITIONS WILL
BE POSSIBLE AT KJCT...BUT OVERALL EXPECT VFR CONDITIONS TO PREVAIL
AT ALL SITES THROUGH THE NEXT 24 HOURS. SOUTH WINDS WILL INCREASE TO
12 TO 16 KNOTS BY MID MORNING FRIDAY.
&&
.PREV DISCUSSION... /ISSUED 1141 AM CDT THU AUG 23 2012/
UPDATE...
TO EXTEND POPS FARTHER EAST...
DISCUSSION...
LIGHT SHOWERS ARE ONGOING ACROSS PARTS OF THE NORTHERN EDWARDS
PLATEAU AND WESTERN CONCHO VALLEY. I WENT AHEAD AND EXTENDED POPS
TO INCLUDE MUCH OF WEST CENTRAL TEXAS THIS AFTERNOON AS MODELS
CONTINUE TO INDICATE AT LEAST ISOLATED SHOWERS AND THUNDERSTORMS
DEVELOPING. LAST SEVERAL RUNS OF THE HRRR INDICATE DECENT SURFACE
CONVERGENCE DEVELOPING ACROSS THE NORTHERN CONCHO VALLEY AND BIG
COUNTRY THIS AFTERNOON...WITH SCATTERED CONVECTION DEVELOPING. IN
ADDITION...DAYTIME HEATING WILL RESULT IN A MORE UNSTABLE
ENVIRONMENT WITH A DECREASING CAP. I EXTENDED SLIGHT CHANCE POPS
TO INCLUDE ALL OF THE AREA EXCEPT FOR PARTS OF THE NORTHWEST HILL
COUNTRY. I ALSO TWEAKED MAX TEMPERATURES DOWN SLIGHTLY OVER THE
WESTERN COUNTIES WHERE MORE CLOUD COVER IS FORECAST.
OTHERWISE...NO OTHER CHANGES NEEDED AT THIS TIME.
PREV DISCUSSION... /ISSUED 739 AM CDT THU AUG 23 2012/
DISCUSSION...
SEE 12Z AVIATION DISCUSSION BELOW.
AVIATION...
SATELLITE SHOWING A FEW LOW CLOUDS TRYING TO DEVELOP THIS MORNING
OVER THE NORTHWEST HILL COUNTRY. BRADY AIRPORT BRIEFLY HAD MVFR
CEILINGS YESTERDAY MORNING...BUT COVERAGE RIGHT NOW ON SATELLITE
NOT LOOKING AS PROMISING FOR TODAY. ADDED SCATTERED LOW CLOUDS FOR
A FEW HOURS THIS MORNING FOR JCT AND BBD. ELSEWHERE...EXPECT VFR
CONDITIONS. COULD SEE A LITTLE MORE WIDESPREAD LOW CLOUD COVERAGE
FOR TOMORROW MORNING...BUT CONFIDENCE LOW ENOUGH AND IT IS AT THE
END OF THIS TAF PERIOD...SO LEFT IT OUT FOR NOW. EXPECT SOUTHEAST
WINDS GENERALLY LESS THAN 15 KT.
PREV DISCUSSION... /ISSUED 424 AM CDT THU AUG 23 2012/
SHORT TERM...
NORTHWEST FLOW ALOFT CONTINUES OVER WEST CENTRAL TEXAS WITH A SERIES
OF WEAK EMBEDDED SHORTWAVE TROUGHS CONTINUING TO MOVE SOUTHEASTWARD
ACROSS THE AREA. A FEW LIGHT SHOWERS/VIRGA CURRENTLY ONGOING THIS
MORNING OVER IRION AND CROCKETT COUNTIES...WITH A FEW MORE SHOWERS
FURTHER BACK OVER THE PERMIAN BASIN. HAVE INCLUDED SLIGHT CHANCE OF
PRECIPITATION FOR FAR SOUTHWESTERN PART OF THE CWA FOR THE
MORNING...BUT DO NOT EXPECT MUCH CHANCE OF MEASURABLE RAINFALL WITH
THESE SHOWERS. WILL CONTINUE WITH A SLIGHT CHANCE OF PRECIP FOR THE
EVENING AS WELL IN THE SAME AREAS AS EXPECT TO SEE A FEW DIURNALLY
DRIVEN SHOWERS FOR THE AFTERNOON/EVENING AS WELL. WILL CONTINUE TO
SEE INCREASED CLOUD COVER FROM MID LEVEL CLOUDS WHICH WILL KEEP
AFTERNOON HIGHS GENERALLY IN THE LOWER TO MID 90S.
07
LONG TERM...
UPPER LOW OVER 4 CORNERS REGION PASSES OVER COLORADO AND INTO THE
CENTRAL PLAINS FRIDAY AND SATURDAY. KEEPING A SLIGHT CHANCE OF
STORMS IN DURING THIS PERIOD...NOT ONLY FOR THE UPPER DISTURBANCE
BUT WITH LOW LEVEL CONVERGENCE AS A SURFACE TROUGH DEVELOPS TO THE
LEE OF THE ROCKY MTS. BEST LIFT AND RAIN CHANCES WILL BE IN
WESTERN SECTIONS OF THE CONCHO VALLEY AND IN THE BIG COUNTRY.
GFS STILL HINTS AT A WEAK COLD FRONT MONDAY INTO TUESDAY...THOUGH
THE EC MODEL HANGS IT FARTHER NORTH ALONG THE RED RIVER. WILL
LEAVE OUT POPS FOR EARLY NEXT WEEK HOWEVER...WITH WEAKLY
SUBSIDENT CONDITIONS ASSOCIATED WITH UPPER LEVEL RIDGING. MIDWEEK
NEXT WEEK...THERE IS SOME DEPENDENCE IN THE TRACK OF ISAAC IN THE
GULF. 00Z GFS HOWEVER BRINGS IN DRIER NE LOW LEVEL FLOW OVER
TEXAS AS ISSAC MOVES INTO THE NE GULF OF MEXICO. THIS WOULD REDUCE
ALREADY REMOTE RAIN CHANCES...AND WILL KEEP WEDNESDAY DRY ALSO.
04
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 72 93 72 93 74 / 10 20 20 20 10
SAN ANGELO 72 95 71 97 73 / 10 20 20 20 10
JUNCTION 69 94 72 97 74 / 10 10 20 10 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DANIELS
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1141 AM CDT THU AUG 23 2012
.UPDATE...
TO EXTEND POPS FARTHER EAST...
&&
.DISCUSSION...
LIGHT SHOWERS ARE ONGOING ACROSS PARTS OF THE NORTHERN EDWARDS
PLATEAU AND WESTERN CONCHO VALLEY. I WENT AHEAD AND EXTENDED POPS
TO INCLUDE MUCH OF WEST CENTRAL TEXAS THIS AFTERNOON AS MODELS
CONTINUE TO INDICATE AT LEAST ISOLATED SHOWERS AND THUNDERSTORMS
DEVELOPING. LAST SEVERAL RUNS OF THE HRRR INDICATE DECENT SURFACE
CONVERGENCE DEVELOPING ACROSS THE NORTHERN CONCHO VALLEY AND BIG
COUNTRY THIS AFTERNOON...WITH SCATTERED CONVECTION DEVELOPING. IN
ADDITION...DAYTIME HEATING WILL RESULT IN A MORE UNSTABLE
ENVIRONMENT WITH A DECREASING CAP. I EXTENDED SLIGHT CHANCE POPS
TO INCLUDE ALL OF THE AREA EXCEPT FOR PARTS OF THE NORTHWEST HILL
COUNTRY. I ALSO TWEAKED MAX TEMPERATURES DOWN SLIGHTLY OVER THE
WESTERN COUNTIES WHERE MORE CLOUD COVER IS FORECAST.
OTHERWISE...NO OTHER CHANGES NEEDED AT THIS TIME.
&&
.PREV DISCUSSION... /ISSUED 739 AM CDT THU AUG 23 2012/
DISCUSSION...
SEE 12Z AVIATION DISCUSSION BELOW.
AVIATION...
SATELLITE SHOWING A FEW LOW CLOUDS TRYING TO DEVELOP THIS MORNING
OVER THE NORTHWEST HILL COUNTRY. BRADY AIRPORT BRIEFLY HAD MVFR
CEILINGS YESTERDAY MORNING...BUT COVERAGE RIGHT NOW ON SATELLITE
NOT LOOKING AS PROMISING FOR TODAY. ADDED SCATTERED LOW CLOUDS FOR
A FEW HOURS THIS MORNING FOR JCT AND BBD. ELSEWHERE...EXPECT VFR
CONDITIONS. COULD SEE A LITTLE MORE WIDESPREAD LOW CLOUD COVERAGE
FOR TOMORROW MORNING...BUT CONFIDENCE LOW ENOUGH AND IT IS AT THE
END OF THIS TAF PERIOD...SO LEFT IT OUT FOR NOW. EXPECT SOUTHEAST
WINDS GENERALLY LESS THAN 15 KT.
PREV DISCUSSION... /ISSUED 424 AM CDT THU AUG 23 2012/
SHORT TERM...
NORTHWEST FLOW ALOFT CONTINUES OVER WEST CENTRAL TEXAS WITH A SERIES
OF WEAK EMBEDDED SHORTWAVE TROUGHS CONTINUING TO MOVE SOUTHEASTWARD
ACROSS THE AREA. A FEW LIGHT SHOWERS/VIRGA CURRENTLY ONGOING THIS
MORNING OVER IRION AND CROCKETT COUNTIES...WITH A FEW MORE SHOWERS
FURTHER BACK OVER THE PERMIAN BASIN. HAVE INCLUDED SLIGHT CHANCE OF
PRECIPITATION FOR FAR SOUTHWESTERN PART OF THE CWA FOR THE
MORNING...BUT DO NOT EXPECT MUCH CHANCE OF MEASURABLE RAINFALL WITH
THESE SHOWERS. WILL CONTINUE WITH A SLIGHT CHANCE OF PRECIP FOR THE
EVENING AS WELL IN THE SAME AREAS AS EXPECT TO SEE A FEW DIURNALLY
DRIVEN SHOWERS FOR THE AFTERNOON/EVENING AS WELL. WILL CONTINUE TO
SEE INCREASED CLOUD COVER FROM MID LEVEL CLOUDS WHICH WILL KEEP
AFTERNOON HIGHS GENERALLY IN THE LOWER TO MID 90S.
07
LONG TERM...
UPPER LOW OVER 4 CORNERS REGION PASSES OVER COLORADO AND INTO THE
CENTRAL PLAINS FRIDAY AND SATURDAY. KEEPING A SLIGHT CHANCE OF
STORMS IN DURING THIS PERIOD...NOT ONLY FOR THE UPPER DISTURBANCE
BUT WITH LOW LEVEL CONVERGENCE AS A SURFACE TROUGH DEVELOPS TO THE
LEE OF THE ROCKY MTS. BEST LIFT AND RAIN CHANCES WILL BE IN
WESTERN SECTIONS OF THE CONCHO VALLEY AND IN THE BIG COUNTRY.
GFS STILL HINTS AT A WEAK COLD FRONT MONDAY INTO TUESDAY...THOUGH
THE EC MODEL HANGS IT FARTHER NORTH ALONG THE RED RIVER. WILL
LEAVE OUT POPS FOR EARLY NEXT WEEK HOWEVER...WITH WEAKLY
SUBSIDENT CONDITIONS ASSOCIATED WITH UPPER LEVEL RIDGING. MIDWEEK
NEXT WEEK...THERE IS SOME DEPENDENCE IN THE TRACK OF ISAAC IN THE
GULF. 00Z GFS HOWEVER BRINGS IN DRIER NE LOW LEVEL FLOW OVER
TEXAS AS ISSAC MOVES INTO THE NE GULF OF MEXICO. THIS WOULD REDUCE
ALREADY REMOTE RAIN CHANCES...AND WILL KEEP WEDNESDAY DRY ALSO.
04
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 92 72 93 72 93 / 20 10 20 20 20
SAN ANGELO 95 72 95 71 97 / 20 10 20 20 20
JUNCTION 95 69 94 72 97 / 20 10 10 20 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DANIELS
AREA FORECAST DISCUSSION...UPDATED
NWS AMARILLO TX
637 AM CDT THU AUG 23 2012
.AVIATION...
FOR THE 12Z TAFS...VFR CONDITIONS ARE EXPECTED OUTSIDE OF TSRA.
PRIMARY CONCERN IS POTENTIAL FOR TSRA THIS AFTERNOON AND EVENING.
HIGHEST POTENTIAL APPEARS TO BE AT KDHT AND KGUY. DELAYED START OF
VCTS AT KDHT TO 01Z-05Z AND INSERTED VCTS REMARKS AT KGUY 23Z-04Z.
HAVE SOMEWHAT LOW CONFIDENCE ON TIMING. THERE IS A POSSIBILITY KAMA
COULD BE IMPACTED 23Z-03Z...BUT CONFIDENCE IS TOO LOW TO MENTION VCTS
AT THIS TIME. BRIEF IFR CONDITIONS WILL BE POSSIBLE IF TSRA DIRECTLY
IMPACTS A TERMINAL.
JACKSON
&&
.PREV DISCUSSION... /ISSUED 437 AM CDT THU AUG 23 2012/
DISCUSSION...
THE GOING THINKING FOR THE FCST PACKAGE REMAINS PRETTY SIMILAR TO
PREVIOUS SHIFTS WITH A GENERALLY UNSETTLED PATTERN TO PREVAIL
THROUGH THE WEEKEND. IT DOES HOWEVER REMAIN DIFFICULT TO PIN DOWN
THE MOST LIKELY PERIODS FOR SHOWERS AND STORMS AS OVERALL FORCING
REMAINS PRETTY WEAK...AND SHRTWV ENERGY IS NOT BEING HANDLED WELL IN
THE MODELS. WHILE PARTS IF NOT MOST OF THE PANHANDLES SHOULD GET AT
LEAST SOME RAIN OVER THE NEXT 3 DAYS...MODEL DISCREPANCIES MAKE THIS
A LOW CONFIDENCE FCST. IT LOOKS LIKE THE FAVORED AREA FOR PRECIP MORE
OFTEN THAN NOT IS GOING TO BE THE ERN HALF OF THE CWA. WHILE ISOLATED
PULSE OR MULTICELL SVR WX MAY BE NOTED THE NEXT 3 AFTERNOONS...
WIDESPREAD SVR WX IS NOT EXPECTED DUE TO GENERALLY LIMITED SHEAR.
TODAY...
AS HAS BEEN THE CASE RECENTLY...MODEL PROGGED INSTABILITY VARIES
GREATLY AGAIN THIS AFTERNOON WITH ANYWHERE FROM NAM DEPICTED 700
J/KG TO RUC DEPICTED 2500 J/KG MLCAPE FCST THIS AFTERNOON. SOME OF
THE AFTERNOON INSTABILITY WILL HINGE ON THE EXTENT OF MID AND HIGH
CLOUDS...WHICH LOOK TO BE OVERDONE IN THE NAM. THEREFORE...SIMILAR
TO THIS PAST MON...WILL SIDE WITH THE SREF...WHICH SHOWS A GOOD
COMPROMISE CLOSER TO THE RUC WITH ABOUT 2000 J/KG MLCAPE BY LATER
THIS AFTERNOON. WHAT THE MODELS DO AGREE ON IS THAT INHIBITION
SHOULD BE WEAK THIS AFTERNOON. SO...IN SPITE OF ONLY WEAK SYNOPTIC
FORCING DUE TO A VERY WEAK SHRTWV...HAVE DECIDED TO INCREASE PRECIP
CHCS THIS AFTERNOON GIVEN THE PREFERENCE TOWARD HIGHER INSTABILITY.
ISOLATED STRONG TO SVR STORMS WILL BE POSSIBLE WITH LARGE HAIL AND
DAMAGING WINDS THE MAIN THREATS. THE SVR THREAT SHOULD DIMINISH AS
WE HEAD INTO THE NIGHTTIME HRS.
TONIGHT...
TONIGHT/S PD HAS BECOME QUITE TRICKY AS OVERNIGHT PRECIP CHCS WILL
BE SOMEWHAT MODULATED BY AFTERNOON CONVECTION /OR LACK THEREOF/. HAVE
LEFT GOING 40 PERCENT POPS...BUT THE THINKING IS THAT THE BEST CHCS
MAY BE BEFORE MIDNIGHT. IN SPITE OF AN INCREASING LLJ...IT APPEARS
THE AREA WILL BE UNDER THE INFLUENCE OF WEAK UPR SUBSIDENCE IN THE
WAKE OF THE AFTERNOON SHRTWV.
FRIDAY AND FRIDAY NIGHT...
AGAIN...CONFIDENCE AND TIMING OF SHRTWV RIPPLES OF ENERGY MAKE THESE
PDS TOUGH TO PIN DOWN...BUT AMPLE MSTR SHOULD AGAIN PROMOTE AT LEAST
CHCS FOR PRECIP. IT APPEARS THE BEST CHC MAY LIE WITH AFTERNOON
CONVECTION FRI AFTERNOON AND EVENING...BUT A MODEST LLJ COULD ALSO
PROMOTE PRECIP FRI NIGHT. AGAIN...DEPENDING ON INSTABILITY...SOME
SVR WX COULD BE NOTED FRI AFTERNOON.
SATURDAY THROUGH SUNDAY...
IF CURRENT MODEL PROGS HOLD...SAT AFTERNOON SHOULD BE A FAVORED
PERIOD FOR SHOWERS AND STORMS AS A FINAL...AND LIKELY STRONGER
SHRTWV TROUGH KICKS THROUGH THE AREA. HAVE LEFT SLIGHT CHCS FOR POPS
GOING FOR SUN...BUT PRECIP POTENTIAL DOES NOT LOOK ALL THAT
IMPRESSIVE ON SUN.
MONDAY ONWARD...
DISCREPANCY EXISTS IN MED RANGE MODELS WITH PLACEMENT AND STRENGTH
OF A REBUILDING UPR RIDGE OVER THE ERN ROCKIES/HIGH PLAINS...WITH
MUCH OF THE UNCERTAINTY DUE TO QUESTIONS ABOUT THE TRACK OF ISAAC
AND IT/S AFFECT ON THE UPR PATTERN. MOST SIGNS DO POINT TO A DRY AND
WARM PD FROM MON THROUGH MUCH OF THE NEXT WORK WEEK.
HEAVY RAIN THREAT...
WITH PWATS ABOVE 1.5 INCHES FOR A GOOD PART OF THE NEXT 3 DAYS...
DEEP WARM CLOUD LAYERS AOA 10KFT...TALL CAPE PROFILES...AND FAIRLY
SLOW STORM MOTIONS...SHOWERS AND STORMS STAND TO BE EFFICIENT PRECIP
PRODUCERS. HOWEVER...A LACK OF LOW LVL FOCUSING BNDRYS MAY KEEP
TRAINING TSTORMS TO A RELATIVE MINIMUM...KEEPING ANY FLASH FLOODING
ISOLATED.
TEMPERATURE-WISE...
HIGHS WILL GENERALLY BE NEAR TO SLIGHTLY ABOVE NORMAL THROUGH THE
WEEKEND...PUSHING A LITTLE FURTHER ABOVE NORMAL BY NEXT WEEK. LOWS
WILL BE ABOVE NORMAL THROUGH THE PD.
SIMPSON
FIRE WEATHER...
NEITHER ELEVATED NOR CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED
THROUGH THE NEXT SEVERAL DAYS...THOUGH BREEZY SOUTHERLY WINDS WILL BE
NOTED THROUGH SATURDAY.
SIMPSON
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
JJ/BJS
AREA FORECAST DISCUSSION
NWS AMARILLO TX
437 AM CDT THU AUG 23 2012
.DISCUSSION...
THE GOING THINKING FOR THE FCST PACKAGE REMAINS PRETTY SIMILAR TO
PREVIOUS SHIFTS WITH A GENERALLY UNSETTLED PATTERN TO PREVAIL
THROUGH THE WEEKEND. IT DOES HOWEVER REMAIN DIFFICULT TO PIN DOWN
THE MOST LIKELY PERIODS FOR SHOWERS AND STORMS AS OVERALL FORCING
REMAINS PRETTY WEAK...AND SHRTWV ENERGY IS NOT BEING HANDLED WELL IN
THE MODELS. WHILE PARTS IF NOT MOST OF THE PANHANDLES SHOULD GET AT
LEAST SOME RAIN OVER THE NEXT 3 DAYS...MODEL DISCREPANCIES MAKE THIS
A LOW CONFIDENCE FCST. IT LOOKS LIKE THE FAVORED AREA FOR PRECIP MORE
OFTEN THAN NOT IS GOING TO BE THE ERN HALF OF THE CWA. WHILE ISOLATED
PULSE OR MULTICELL SVR WX MAY BE NOTED THE NEXT 3 AFTERNOONS...
WIDESPREAD SVR WX IS NOT EXPECTED DUE TO GENERALLY LIMITED SHEAR.
TODAY...
AS HAS BEEN THE CASE RECENTLY...MODEL PROGGED INSTABILITY VARIES
GREATLY AGAIN THIS AFTERNOON WITH ANYWHERE FROM NAM DEPICTED 700
J/KG TO RUC DEPICTED 2500 J/KG MLCAPE FCST THIS AFTERNOON. SOME OF
THE AFTERNOON INSTABILITY WILL HINGE ON THE EXTENT OF MID AND HIGH
CLOUDS...WHICH LOOK TO BE OVERDONE IN THE NAM. THEREFORE...SIMILAR
TO THIS PAST MON...WILL SIDE WITH THE SREF...WHICH SHOWS A GOOD
COMPROMISE CLOSER TO THE RUC WITH ABOUT 2000 J/KG MLCAPE BY LATER
THIS AFTERNOON. WHAT THE MODELS DO AGREE ON IS THAT INHIBITION
SHOULD BE WEAK THIS AFTERNOON. SO...IN SPITE OF ONLY WEAK SYNOPTIC
FORCING DUE TO A VERY WEAK SHRTWV...HAVE DECIDED TO INCREASE PRECIP
CHCS THIS AFTERNOON GIVEN THE PREFERENCE TOWARD HIGHER INSTABILITY.
ISOLATED STRONG TO SVR STORMS WILL BE POSSIBLE WITH LARGE HAIL AND
DAMAGING WINDS THE MAIN THREATS. THE SVR THREAT SHOULD DIMINISH AS
WE HEAD INTO THE NIGHTTIME HRS.
TONIGHT...
TONIGHT/S PD HAS BECOME QUITE TRICKY AS OVERNIGHT PRECIP CHCS WILL
BE SOMEWHAT MODULATED BY AFTERNOON CONVECTION /OR LACK THEREOF/. HAVE
LEFT GOING 40 PERCENT POPS...BUT THE THINKING IS THAT THE BEST CHCS
MAY BE BEFORE MIDNIGHT. IN SPITE OF AN INCREASING LLJ...IT APPEARS
THE AREA WILL BE UNDER THE INFLUENCE OF WEAK UPR SUBSIDENCE IN THE
WAKE OF THE AFTERNOON SHRTWV.
FRIDAY AND FRIDAY NIGHT...
AGAIN...CONFIDENCE AND TIMING OF SHRTWV RIPPLES OF ENERGY MAKE THESE
PDS TOUGH TO PIN DOWN...BUT AMPLE MSTR SHOULD AGAIN PROMOTE AT LEAST
CHCS FOR PRECIP. IT APPEARS THE BEST CHC MAY LIE WITH AFTERNOON
CONVECTION FRI AFTERNOON AND EVENING...BUT A MODEST LLJ COULD ALSO
PROMOTE PRECIP FRI NIGHT. AGAIN...DEPENDING ON INSTABILITY...SOME
SVR WX COULD BE NOTED FRI AFTERNOON.
SATURDAY THROUGH SUNDAY...
IF CURRENT MODEL PROGS HOLD...SAT AFTERNOON SHOULD BE A FAVORED
PERIOD FOR SHOWERS AND STORMS AS A FINAL...AND LIKELY STRONGER
SHRTWV TROUGH KICKS THROUGH THE AREA. HAVE LEFT SLIGHT CHCS FOR POPS
GOING FOR SUN...BUT PRECIP POTENTIAL DOES NOT LOOK ALL THAT
IMPRESSIVE ON SUN.
MONDAY ONWARD...
DISCREPANCY EXISTS IN MED RANGE MODELS WITH PLACEMENT AND STRENGTH
OF A REBUILDING UPR RIDGE OVER THE ERN ROCKIES/HIGH PLAINS...WITH
MUCH OF THE UNCERTAINTY DUE TO QUESTIONS ABOUT THE TRACK OF ISAAC
AND IT/S AFFECT ON THE UPR PATTERN. MOST SIGNS DO POINT TO A DRY AND
WARM PD FROM MON THROUGH MUCH OF THE NEXT WORK WEEK.
HEAVY RAIN THREAT...
WITH PWATS ABOVE 1.5 INCHES FOR A GOOD PART OF THE NEXT 3 DAYS...
DEEP WARM CLOUD LAYERS AOA 10KFT...TALL CAPE PROFILES...AND FAIRLY
SLOW STORM MOTIONS...SHOWERS AND STORMS STAND TO BE EFFICIENT PRECIP
PRODUCERS. HOWEVER...A LACK OF LOW LVL FOCUSING BNDRYS MAY KEEP
TRAINING TSTORMS TO A RELATIVE MINIMUM...KEEPING ANY FLASH FLOODING
ISOLATED.
TEMPERATURE-WISE...
HIGHS WILL GENERALLY BE NEAR TO SLIGHTLY ABOVE NORMAL THROUGH THE
WEEKEND...PUSHING A LITTLE FURTHER ABOVE NORMAL BY NEXT WEEK. LOWS
WILL BE ABOVE NORMAL THROUGH THE PD.
SIMPSON
&&
.FIRE WEATHER...
NEITHER ELEVATED NOR CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED
THROUGH THE NEXT SEVERAL DAYS...THOUGH BREEZY SOUTHERLY WINDS WILL BE
NOTED THROUGH SATURDAY.
SIMPSON
&&
.PRELIMINARY POINT TEMPS/POPS...
AMARILLO TX 89 67 89 66 88 / 40 40 30 30 30
BEAVER OK 96 69 92 70 91 / 40 40 40 40 30
BOISE CITY OK 94 66 89 63 91 / 40 40 40 30 30
BORGER TX 92 70 92 69 89 / 40 40 30 30 30
BOYS RANCH TX 94 69 95 66 92 / 40 40 30 30 30
CANYON TX 89 67 91 66 89 / 40 40 30 20 30
CLARENDON TX 89 70 91 68 90 / 40 40 30 30 30
DALHART TX 93 65 93 63 89 / 40 40 30 30 30
GUYMON OK 94 69 91 66 91 / 40 40 40 40 30
HEREFORD TX 88 66 90 63 89 / 40 40 30 20 30
LIPSCOMB TX 92 70 88 70 89 / 40 40 40 40 30
PAMPA TX 89 68 89 67 86 / 40 40 40 30 30
SHAMROCK TX 90 70 90 69 89 / 40 40 40 40 30
WELLINGTON TX 92 70 93 70 92 / 40 40 40 30 30
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
13/09
AREA FORECAST DISCUSSION...UPDATED
NWS SAN ANGELO TX
1150 PM CDT WED AUG 22 2012
.DISCUSSION...
SEE 06Z AVIATION DISCUSSION BELOW.
&&
.AVIATION...
NO SIGNIFICANT CHANGES TO THE PREVIOUS SET OF TAFS. VFR CONDITIONS
STILL EXPECTED ACROSS THE TAF SITES THROUGH THE NEXT 24 HOURS. WE
MAY SEE SCT MVFR CIGS EARLY IN THE MORNING FOR A BRIEF PERIOD...
BUT THE COVERAGE IS NOT EXPECTED TO BE WIDESPREAD ENOUGH TO
WARRANT ANY PREVAILING GROUPS AT ANY PARTICULAR SITE.
OTHERWISE...HAVE ONLY INSERTED A WIND DIRECTION CHANGE IN THE
MORNING FOR WINDS TURNING MORE SOUTHERLY AS MIXING WITH SOUTHERLY
WINDS OFF THE SURFACE TAKES PLACE DURING THE MORNING HOURS.
&&
.PREV DISCUSSION... /ISSUED 944 PM CDT WED AUG 22 2012/
DISCUSSION...
HAVE UPDATED THE FORECAST TO REMOVE POPS/WX FOR THE REST OF THE
EVENING AS THE ISOLATED SHOWERS TO OUR SOUTH HAVE DISSIPATED WITH
THE LOSS OF DAYTIME HEATING. THERE ARE FEW SHOWERS TO OUR WEST IN
THE PERMIAN BASIN ASSOCIATED WITH WEAK UPPER LEVEL SHORTWAVE
ENERGY. HOWEVER...THESE SHOWERS HAVE BEEN FORMING AND WEAKENING
RATHER QUICKLY AS THEY MOVE EAST...AND WE EXPECT THAT TREND TO
CONTINUE...PREVENTING THEM FROM MAKING IT INTO OUR CWA. NO OTHER
SIGNIFICANT CHANGES WERE NEEDED.
20
PREV DISCUSSION... /ISSUED 607 PM CDT WED AUG 22 2012/
DISCUSSION...
SEE 00Z AVIATION DISCUSSION BELOW.
AVIATION...
MAINLY VFR CONDITIONS ARE EXPECTED AT THE TERMINALS THE NEXT 24
HOURS. LCL MVFR CIGS MAY DEVELOP ACROSS THE NORTHWEST HILL COUNTRY
AND HEARTLAND LATE TONIGHT AND THURSDAY MORNING. HOWEVER...WILL
KEEP VFR CONDITIONS GOING AT THE KBBD AND KJCT TAF SITES FOR NOW.
WINDS WILL BE MAINLY SOUTHEAST AT 5 TO 15 KNOTS.
21
PREV DISCUSSION... /ISSUED 314 PM CDT WED AUG 22 2012/
SHORT TERM...
EARLIER SHOWERS AND STORMS ACROSS THE BIG COUNTRY HAVE NOW
DISSIPATED FOR THE MOMENT. HOWEVER...CU FIELD HAS STARTED TO DEVELOP
ONCE AGAIN...AND THE VARIOUS WRF MODELS AND THE HRRR ALL SHOW SOME
VARYING DEGREE OF CONVECTION POPPING UP ACROSS WEST CENTRAL TEXAS
FOR A FEW HOURS LATE THIS AFTERNOON AND INTO THE EVENING. WILL
INCLUDE A MENTION OF ISOLATED STORMS FOR THE FIRST PERIOD.
OTHERWISE...FAIRLY QUIET PATTERN FOR THE NEXT 36 HOURS. LEE TROUGH
BECOMES BETTER ESTABLISHED ACROSS THE EASTERN NEW MEXICO AND WEST
TEXAS...WITH SOUTHERLY WINDS INCREASING AHEAD OF IT. MORE HIGH
CLOUDS ON THURSDAY......BUT NOT ENOUGH TO HAVE A REALLY SIGNIFICANT
EFFECT ON TEMPERATURES.
07
LONG TERM...
A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS IS FORECAST FOR PARTS
OF THE AREA DURING THE FIRST PART OF THE EXTENDED FORECAST. AN UPPER
LEVEL HIGH WILL BEGIN TO SHIFT SOUTH INTO MEXICO THURSDAY...WHILE AN
UPPER LEVEL TROUGH APPROACHES FROM THE WEST. AT THE SAME TIME A LEE
TROUGH WILL DEVELOP OVER THE TEXAS PANHANDLE...RESULTING IN
INCREASING SOUTH TO SOUTHEAST WINDS. SHOWERS AND THUNDERSTORMS MAY
DEVELOP OVER PARTS OF WEST TEXAS BY LATE AFTERNOON/EARLY EVENING
THURSDAY...WHERE BETTER SURFACE CONVERGENCE IS EXPECTED. A FEW OF
THESE STORMS MAY DRIFT INTO PARTS OF OUR WESTERN COUNTIES...SO HAVE
INCLUDED SLIGHT CHANCE POPS AFTER 00Z FRIDAY.
MODELS ARE HINTING AT A COUPLE OF SHORTWAVE TROUGHS MOVING ACROSS
NORTH TEXAS. THE FIRST IS WEAKER AND IS FORECAST TO TREK ACROSS THE
PANHANDLE EARLY FRIDAY MORNING. AT THIS TIME...BELIEVE THE MAJORITY
OF PRECIPITATION WILL REMAIN NORTH OF OUR AREA...BUT KEPT SLIGHT
CHANCE POPS OVER THE NORTHERN BIG COUNTRY. THE NEXT...MORE
POTENT...UPPER LEVEL SHORTWAVE TROUGH WILL APPROACH FRIDAY THEN MOVE
ACROSS NORTH TEXAS AND OKLAHOMA SATURDAY. ONCE AGAIN...ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE...WITH THE
FAVORED AREAS BEING OUR NORTHERN AND WESTERN COUNTIES. I KEPT SLIGHT
CHANCE POPS IN FOR FRIDAY AND INTRODUCED SLIGHT CHANCE POPS ON
SATURDAY FOR THE WESTERN HALF OF THE REGION. BEYOND
SATURDAY...MODELS ARE HINTING AT A WEAK COLD FRONT MOVING INTO THE
TEXAS PANHANDLE SUNDAY...WITH SCATTERED SHOWERS AND THUNDERSTORMS
DEVELOPING JUST NORTH OF OUR AREA. FOR NOW...I HAVE LEFT THE
FORECAST DRY BEYOND SATURDAY...BUT FUTURE SHIFTS MAY NEED TO
INTRODUCE POPS. HIGH TEMPERATURES THROUGH THE EXTENDED WILL BE NEAR
TO SLIGHTLY ABOVE NORMAL THROUGH THE PERIOD...GENERALLY IN THE MID
90S.
DANIELS
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 71 94 73 93 74 / 10 10 10 20 20
SAN ANGELO 71 95 73 95 75 / 10 10 10 20 20
JUNCTION 71 93 72 94 74 / 10 10 10 10 20
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS AMARILLO TX
1141 PM CDT WED AUG 22 2012
.AVIATION...
06Z TAF CYCLE
AN UPPER RIDGE WILL PREVAIL ACROSS THE PANHANDLES THROUGH THURSDAY
MORNING BEFORE MOVING OFF TO THE EAST AS AN UPPER TROUGH APPROACHES
FROM THE WEST BY THURSDAY AFTERNOON. CONVECTION MAY IMPACT THE
NORTHWEST TEXAS PANHANDLE AFTER 20Z THURSDAY...THEREFORE WILL INCLUDE
A VCTS REMARK FOR THE DALHART TAF SITE BETWEEN ABOUT 20Z THURSDAY AND
02Z FRIDAY. OTHERWISE...CONFIDENCE TOO LOW FOR THE GUYMON AND
AMARILLO TAF SITES WHICH MAY BE IMPACTED BY CONVECTION AFTER 00Z
FRIDAY. VFR CONDITIONS WILL PREVAIL. SOUTHEASTERLY WINDS 10 TO 20
KNOTS WITH SOME HIGHER GUSTS TONIGHT WILL BECOME SOUTHERLY TO
SOUTHWESTERLY 15 TO 25 KNOTS WITH HIGHER GUSTS AFTER 15Z
THURSDAY...AND THEN BECOME SOUTHERLY TO SOUTHEASTERLY AGAIN AFTER 00Z
FRIDAY 10 TO 20 KNOTS.
SCHNEIDER
&&
.PREV DISCUSSION... /ISSUED 1042 PM CDT WED AUG 22 2012/
UPDATE...
HAVE TRIMMED POPS BACK ACROSS THE WESTERN ZONES TONIGHT AS AREA OF
THUNDERSTORMS CONTINUE TO WEAKEN AS THEY APPROACH THE TX BORDER.
HOWEVER WILL HOLD ONTO SLIGHT CHANCE POPS OVERNIGHT ACROSS THE
FORECAST AREA AS A LOW LEVEL JET SETS UP ACROSS THE SOUTHERN PLAINS.
REMAINDER OF THE FORECAST IS IN GOOD SHAPE WITH ONLY MINOR
ADJUSTMENTS TO SKY GRIDS NEEDED. UPDATED FORECASTS HAVE BEEN SENT.
CLK
PREV DISCUSSION... /ISSUED 630 PM CDT WED AUG 22 2012/
AVIATION...
AN UPPER RIDGE WILL PREVAIL ACROSS THE THREE TAF SITES TONIGHT AND
EARLY THURSDAY BEFORE AN UPPER TROUGH APPROACHES FROM THE WEST. VFR
CONDITIONS WILL PREVAIL THROUGH THE TAF FORECAST PERIOD. SOME SHOWERS
MAY AFFECT THE DALHART TAF SITE THIS EVENING...BETWEEN 00Z AND 04Z
THURSDAY...HOWEVER CONFIDENCE LOW. SOUTHEAST TO SOUTH WINDS 10 TO 20
KNOTS WILL DIMINISH TO AROUND 5 TO 15 KNOTS AFTER 02Z THURSDAY...AND
THEN INCREASE AFTER 14Z THURSDAY TO AROUND 15 TO 25 KNOTS WITH HIGHER
GUSTS.
SCHNEIDER
PREV DISCUSSION... /ISSUED 321 PM CDT WED AUG 22 2012/
DISCUSSION...
ALREADY SEEING A TRANSITION FROM NORTHWESTERLY FLOW ALOFT TO MORE
WESTERLY FLOW ALOFT IN RESPONSE TO THE APPROACHING CUTOFF LOW
CURRENTLY IN SOUTHERLY CA.
FOR TONIGHT...STORMS FROM THE HIGHER TERRAIN OF NM AND CO WILL
QUICKLY MOVE INTO THE NORTHWESTERN PANHANDLES. THE RAP IS SHOWING
THIS AREA WITH SLIGHTLY HIGHER CAPE VALUES...NEAR 2000 J/KG...AND
MODEST SHEAR VALUES NEAR 30 KT. HOWEVER...THE SEVERE THREAT SHOULD
NOT LAST LONG AS MODEL SOUNDINGS SHOW ONLY ELEVATED INSTABILITY BY
03Z.
TOMORROW AND TOMORROW NIGHT...WILL PROBABLY BE THE BEST CHANCE FOR A
WIDESPREAD RAIN EVENT...ESPECIALLY TOMORROW NIGHT...WITH VORTICITY
ADVECTION AHEAD OF THE MAIN UPPER LEVEL TROUGH. THE BIGGER CONCERN
HOWEVER WILL BE THE POTENTIAL FOR HEAVY RAIN LEADING TO LOCALIZED
FLASH FLOODING...AS PRECIPITABLE WATER VALUES COULD BE ABOVE 1.5
INCHES AND MEAN STORM MOTIONS COULD BE BELOW 20 KT.
FRIDAY THROUGH SUNDAY...SOME CHANCES FOR THUNDERSTORMS CONTINUE
THROUGH THIS PERIOD. HOWEVER...THERE IS UNCERTAINTY IN THE TRACK OF
THE CENTER OF THE UPPER LEVEL LOW. IF THE LOW GOES JUST SOUTH OF THE
TX PANHANDLE AS THE GFS SHOWS...THERE SHOULD BE A RELATIVELY GOOD
CHANCE FOR RAIN THROUGH THE WEEKEND. HOWEVER...ANY DEVIATION TO THE
NORTH...LIKE THE ECMWF SHOWING THE LOW LIFTING NE ACROSS THE TX
PANHANDLE ON SAT...COULD MEAN THE REGION WOULD BE IN THE PRIME
LOCATION FOR THE DRY SLOT...AND THUS HAVE FEW IF ANY CHANCES FOR
STORMS. LIKELY THIS UNCERTAINTY WILL REMAIN FOR THE NEXT FEW MODEL
RUNS AS THE PATH OF THIS LOW IS SOMEWHAT DEPENDENT ON THE EVOLUTION
OF A SECOND UPPER LEVEL TROUGH THAT SHOULD MOVE ACROSS THE NORTHERN
TIER OF THE U.S. AT THE SAME TIME...BUT HAS NOT YET BEEN WELL SAMPLED
BY THE UPPER AIR NETWORK.
MONDAY THROUGH WEDNESDAY...A RIDGE IS EXPECTED TO BUILD OVER THE HIGH
PLAINS...MINIMIZING THE CHANCE FOR RAIN AND BRINGING A WARMING TREND
AT LEAST TO START THE WEEK.
JOHNSON
FIRE WEATHER...
RELATIVELY HIGH ATMOSPHERIC MOISTURE...AND CONTINUED RAIN CHANCES
SHOULD PRECLUDE ANY ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS FOR
THE NEXT SEVERAL DAYS.
JOHNSON
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
11/05
AREA FORECAST DISCUSSION
NWS NEW YORK NY
424 AM EDT SAT AUG 25 2012
.SYNOPSIS...
HIGH PRESSURE CENTERED NEAR THE CANADIAN MARITIMES WILL TRACK
EASTWARD TODAY THEN BECOMES ELONGATED BACK TOWARDS THE NEW ENGLAND
COAST TONIGHT AND SUNDAY. MEANWHILE...AN UPPER LEVEL LOW OVER THE
MID ATLANTIC WILL MOVE SLOWLY NORTHEAST TOWARD THE AREA. A COLD
FRONT IS FORECAST TO MOVE SOUTHEAST CROSS THE AREA TUESDAY
FOLLOWED BY HIGH PRESSURE WEDNESDAY THROUGH FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A WEAK UPPER LEVEL LOW PRESSURE SYSTEM OVER THE MID ATLANTIC
STATES WILL CONTINUE TO SEND ABUNDANT MID AND HIGH LEVEL CLOUDS
INTO THE AREA TODAY. SOME AREAS MAY EXPERIENCE FILTERED SUNSHINE
THIS MORNING BUT IT WILL EVENTUALLY GIVE WAY TO THICKER CLOUDS
WITH MOSTLY CLOUDY SKIES DEVELOPING BY AFTERNOON.
VORT ENERGY FROM THIS LOW WILL ADVANCE TOWARDS THE AREA TODAY. 00Z
OKX SOUNDING INDICATES A DRY PROFILE HOWEVER...AN ONSHORE FLOW
WILL BE INCREASING LOW LEVEL MOISTURE AND THERE COULD BE A FEW
SHOWERS AROUND. LATEST HRRR DOES INDICATE SOME LIGHT ECHOES EARLY
THIS AFTERNOON ACROSS WESTERN PORTIONS OF THE CWA. HAVE MAINTAINED
SCHC POPS AS A RESULT. HAVE REMOVED MENTION OF THUNDER WITH LITTLE
INSTABILITY FORECAST AND EQL LEVEL FORECAST TO BE AROUND -10C.
SUBSIDENCE FROM DEPARTING HIGH PRES MAY BE ENOUGH TO KEEP EASTERN
AREAS DRY TODAY SO NO POPS.
MOS GUIDANCE WAS CLOSE ON HIGH TEMPS TODAY AND USED A BLEND.
THERE IS A MODERATE RISK OF RIP CURRENTS AT ATLANTIC OCEAN BEACHES
TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
UPPER LEVEL RIDGING OVER THE ATLANTIC BUILDS BACK TOWARDS THE
EAST COAST TONIGHT WITH THE UPPER LEVEL LOW WEAKENING. HAVE GONE
WITH A DRY FORECAST UNTIL LATE TONIGHT THROUGH SUNDAY WITH ONLY SCHC
POPS RETURNING ACROSS WESTERN AREAS AS MAJORITY OF MOISTURE AND
LIFT ASSOCIATED WITH THE MID ATLANTIC SYSTEM ARE FORECAST TO REMAIN TO
OUR SW.
ONSHORE FLOW CONTINUES THROUGH SUN WITH TEMPERATURES NEAR NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
UPPER LEVEL LOW IN MID-ATLANTIC FINALLY GETS ABSORBED INTO MEAN
FLOW SUN NIGHT AND MOVES ACROSS MON MORNING. THIS WILL BE THE BEST
CHC OF THE LOCAL AREA SEEING ANY PRECIP FROM THIS SYSTEM. ELEVATED
INSTABILITY ALSO DEVELOPS SO TSTMS WILL BE POSSIBLE. FCST MODELS
SHOW A STRONGER UPPER LVL TROUGH APPROACHING WITH A HIGHER
PROBABILITY OF SCT SHOWERS AND TSTMS...MAINLY FROM MONDAY AFTN
THROUGH NOON TUESDAY. AS ALWAYS...TIMING THIS FRONTAL PASSAGE WILL
BE A CHALLENGE. AS THIS FRONT MOVES INTO A WARM...MOIST UNSTABLE
MARITIME TROPICAL AIR MASS...A FEW STORMS COULD PRODUCE HVY RAIN
AND STRONG GUSTY WINDS.
TUE NIGHT THROUGH FRI...FCST MODELS SHOW HIGH PRES MVG SE TOWARD
THE AREA COURTESY OF A WELL DEFINED HIGH AMPLITUDE UPSTREAM RIDGE
ACROSS THE WESTERN U.S. THIS WILL REPLACE THE MARITIME TROPICAL AIR
MASS WITH A FRESH AND DRIER CONTINENTAL POLAR AIR MASS.
REGARDING THE FORECAST FOR ISAAC...PLEASE REFER TO THE LATEST
NATIONAL HURRICANE CENTER FORECASTS. AT THIS TIME...IT APPEARS THAT
THE REMNANTS FROM ISAAC MAY PASS SOUTH OF THE LOCAL AREA NEXT
THURSDAY.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
HIGH PRESSURE WILL REMAIN NEAR THE CANADIAN MARITIMES THROUGH THE
DAY TODAY.
EXPECT AREAS OF MVFR OR IFR CONDITIONS IN FOG EARLY THIS
MORNING...MAINLY OUTSIDE OF NYC METRO TERMINALS. OTHERWISE...VFR
WITH MID AND HIGH CLOUDS TODAY. WINDS REMAIN LIGHT EARLY THIS
MORNING...THEN INCREASE FROM THE EAST/SOUTHEAST CLOSE TO 10 KTS BY
AFTERNOON. CANNOT RULE OUT AN ISOLATED SHOWER THIS AFTERNOON...BUT
DO NOT EXPECT COVERAGE TO BE HIGH ENOUGH TO INCLUDE IN THE
FORECAST AT THIS TIME.
OUTLOOK FOR 06Z SUNDAY THROUGH WED...
.SUNDAY...MAINLY VFR. ISOLATED SHOWERS/TSTMS POSSIBLE WITH BRIEF
MVFR OR LOWER CONDS.
.MON-TUE...MVFR OR LOWER CONDS POSSIBLE...ESPECIALLY IN ANY
SHOWERS/TSTMS THAT DEVELOP AS A COLD FRONT APPROACHES.
BEST CHANCES FOR THESE LOWER CONDITIONS TUE INTO TUE NIGHT.
.WED...VFR.
&&
.MARINE...
AS HIGH PRESSURE MOVES AROUND THE CANADIAN MARITIMES AND OFF THE NEW
ENGLAND COAST THROUGH THE REMAINDER OF THE WEEKEND...EXPECT A
PERSISTENT EASTERLY WIND FLOW ACROSS THE LOCAL WATERS. THESE
EASTERLY WINDS WILL SHIFT AROUND THE SOUTH AND SOUTHWEST LATER MONDAY
AND MONDAY NIGHT. THIS WIND SHIFT WILL OCCUR AS THE CENTER OF THE
HIGH DRIFTS EAST AND A COLD FRONT APPROACHES FROM THE NORTHWEST.
THE COLD FRONT WILL PASS ACROSS THE WATERS TUESDAY...FOLLOWED BY
HIGH PRESSURE THROUGH MID WEEK.
SEAS SLOWLY BUILD THIS WEEKEND IN RESPONSE TO THE EASTERLY FLOW...BUT
DO EXPECT WINDS AND SEAS TO REMAIN JUST UNDER SCA CRITERIA.
SEAS SHOULD THEN SETTLE AND REMAIN AROUND 3 OR 4 FT THROUGH THE
EARLY PART OF THE WEEK ACROSS THE OCEAN WATERS.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH THE WEEKEND.
MON THROUGH TUE...SCT HEAVIER SHOWERS AND TSTMS COULD PRODUCE 1/2 TO
1 INCH OF RAIN IN ADVANCE OF AN APPROACHING COLD FRONT. ISOLATED
URBAN FLOODING IS POSSIBLE.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
207 AM CDT SAT AUG 25 2012
.DISCUSSION...
324 PM CDT
TODAY THROUGH SATURDAY NIGHT...
AN UPPER LEVEL DISTURBANCE IS SLOWLY PASSING THROUGH NORTHERN
WISCONSIN AND WILL CONTINUE EASTWARD THROUGH THE NORTHERN GREAT
LAKES THIS EVENING. SOME OF THE SHORT TERM MODELS INDICATE
SCATTERED SHOWERS WILL DEVELOP ACROSS NORTHERN ILLINOIS...BUT WILL
CONTINUE WITH A DRY FORECAST THIS AFTERNOON. LATEST RAP ANALYSIS
INDICATES AMPLE CAPE AND LOW LEVEL LAPSE RATES NEAR DRY
ADIABATIC...HOWEVER SUSPECTING THE RAP ANALYSIS MAY BE OVER
ESTIMATING CAPE VALUES. ALSO TOOK INTO CONSIDERATION THAT THE UPPER
LEVEL WAVE IS WELL NORTH OF THE CWA...AND CONVECTION/SHOWERS OVER
LAKE MICHIGAN ARE ASSOCIATED WITH AN AREA OF 850 HPA WARM AIR
ADVECTION. SCT CU IS BEGINNING TO DEVELOP ROUGHLY ALONG THE I-55
CORRIDOR.
SKIES CLEAR TONIGHT AND EXPECTING A COMFORTABLE NIGHT DESPITE LOW
90S BEING REPORTED ACROSS THE CWA THIS AFTERNOON. OVERNIGHT LOWS
WILL BE IN THE MID 60S...EXCEPT FOR LOW 70S DOWNTOWN. SATURDAY WILL
BE MUCH LIKE TODAY...WITH A DRY AND HOT FORECAST. RAISED INHERITED
TEMPS SUCH THAT TOMORROWS HIGHS ARE A DEGREE OR TWO WARMER THAN
TODAY. COULD EVEN SEE AREAS IN THE SOUTHERN PORTIONS OF THE CWA
BEING A BIT WARMER THAN CURRENTLY FORECAST. MODEL SOUNDINGS
INDICATES THERE WILL BE PLENTY OF MIXING TOMORROW...THEREFORE WENT
WITH DEW POINTS SLIGHTLY LOWER THAN PREVIOUSLY FORECAST. MIN RH
VALUES WILL BE IN THE MID TO UPPER 20 PERCENT RANGE...BUT WITH LIGHT
WINDS FORECAST NOT ANTICIPATING ANY FIRE WEATHER HEADLINES. THAT
BEING SAID A FEW LOCATIONS MAY REACH RED FLAG CRITERIA...AS RFD DID
TODAY. KEPT PREVIOUS MIN TEMPS FOR SATURDAY NIGHT WITH MID TO UPPER
60S IN THE OUTLYING AREAS...AND IN THE LOW 70S DOWNTOWN.
SUNDAY THROUGH MONDAY NIGHT...
LOW PRESSURE CURRENTLY OVER SOUTHERN SASKATCHEWAN AND THE NORTHERN
GREAT PLAINS WILL MOVE EASTWARD ACROSS SOUTHERN CANADA THROUGH THE
WEEKEND. THE LOWS COLD FRONT PASSES THROUGH THE CWA LATE SUNDAY
NIGHT INTO MONDAY MORNING. PRECIP AHEAD OF THE COLD FRONT WAS THE
MAIN FORECAST CHALLENGE TODAY. THE NAM AND GFS LOOKED A BIT FAST
WHILE THE ECMWF HAS BEEN SLOWING THE PROGRESSION OF THE SHOWERS
AND THUNDERSTORMS THE PAST FEW RUNS. WENT WITH A NAM/ECMWF MIX
THAT WAS VERY SIMILAR TO THE PREVIOUS FORECASTS TIMING...WITH
PRECIP REACHING THE WESTERN EDGE OF THE CWA LATE SATURDAY NIGHT.
THAT BEING SAID...THE MODELS ARE INDICATING THE INITIAL UPPER
LEVEL VORTICITY STREAMER ASSOCIATED WITH FIRST WAVE OF PRECIP WILL
BE STRETCHED NORTH TO SOUTH AND FRACTURE SOMEWHERE OVER WISCONSIN.
THE SOUTHERN PART OF THE VORT STREAMER WILL THEN PROGRESS EASTWARD
BRINGING MUCH NEEDED RAIN TO NORTHERN ILLINOIS. CONFIDENCE IS
MEDIUM WITH THE TIMING AND PROGRESSION OF THE PRECIP...BUT HIGH
REGARDING THE POSSIBILITY OF IT BEING A SIGNIFICANT RAINFALL.
PW VALUES WILL BE AROUND TO SLIGHTLY ABOVE 2 INCHES AHEAD OF THE
FRONT...WHICH IS AROUND 2 STANDARD DEVIATIONS ABOVE NORMAL FOR
AUGUST. THEREFORE SUBSTANTIAL RAINFALL IS POSSIBLE AND AS MENTIONED
IN THE PREVIOUS DISCUSSION...TRAINING CELLS COULD CAUSE ISOLATED
WATER PROBLEMS.
TEMPS ON SUNDAY WILL BE MUCH COOLER WITH AREAS WEST OF I-55 IN THE
UPPER 70S...AND LOW TO MID 80S EXPECTED EAST OF I-55. TEMPS REBOUND
SLIGHTLY ON MONDAY WITH HIGHS IN THE LOW TO MID 80S.
EXTENDED...TUESDAY THROUGH FRIDAY...
HIGH PRESSURE MOVES IN BEHIND THE COLD FRONT LEADING TO ANOTHER
EXTENDED PERIOD OF DRY WEATHER. TEMPS INCREASE THROUGHOUT THE
EXTENDED...AND COULD BE EVEN WARMER THAN FORECAST. EXPECTING UPPER
80S TO QUITE POSSIBLY 90S BY LATE NEXT WEEK.
JEE
&&
.FIRE WEATHER...
428 PM CDT
RH VALUES DROPPED INTO THE 20 PERCENT RANGE ACROSS PARTS OF THE
AREA TODAY...AND SIMILAR CONDITIONS ARE EXPECTED TOMORROW.
TEMPERATURES TOMORROW WILL ONCE AGAIN BE IN THE LOW TO MID
90S...WITH LOWER DEW POINTS THAN TODAY. AMPLE MIXING WILL LIKELY
LEAD TO DEW POINTS DROPPING INTO THE LOW 50S SATURDAY AFTERNOON.
MIN RH VALUES WILL BE IN THE LOW TO MID 20 PERCENT RANGE...HOWEVER
WIND SPEEDS WILL BE AROUND 10 MPH. WIND GUSTS WILL DEVELOP IN THE
AFTERNOON WITH GUSTS UP TO 20 MPH EXPECTED WEST OF I-39...AND
GUSTS AROUND 15 MPH EXPECTED EAST OF I-39. FUEL MOISTURE LEVELS
ARE ABOVE 10 PERCENT FOR MUCH OF NORTHERN ILLINOIS...WHILE AREAS
EAST OF I-55 HAVE 10-HOUR FUELS LESS THAN 10 PERCENT. THEREFORE
TWO OF THE THREE RED FLAG CONDITIONS MAY BE MET IN ISOLATED
LOCATIONS...SIMILAR TO TODAY...BUT NOT EXPECTING ALL THREE RED
FLAG CONDITIONS TO BE MET. THEREFORE NO FIRE WEATHER HEADLINES ARE
ANTICIPATED.
A COLD FRONT MOVES THROUGH THE REGION LATE SATURDAY NIGHT INTO
SUNDAY BRINGING A WIDESPREAD SOAKING RAIN AND COOLER TEMPERATURES
WITH IT.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* SPORADIC GUSTS TO 15 KT THIS AFTERNOON.
//DISCUSSION...UPDATED 06Z...
HIGH PRESSURE WILL REMAIN IN CONTROL TO THE EAST OF THE REGION
TODAY WITH LOW PRESSURE BECOMING BETTER ORGANIZED ACROSS THE
CENTRAL PLAINS. WITH SUCH A PATTERN...SOUTHERLY WINDS WILL PREVAIL
AND SHOULD BE AT A SIMILAR MAGNITUDE TO THOSE SEEN ON FRIDAY. A
FEW HIGH BASED CU ARE POSSIBLE...AND ANY LAKE BREEZE IS
ANTICIPATED TO REMAIN TO THE EAST OF ORD AND MDW. AS THE LOW
PRESSURE TROUGH INCHES EAST TONIGHT...UPPER LEVEL CLOUDS WILL BE
ON THE INCREASE. THESE CLOUDS WILL LOWER ON SUNDAY WITH RAIN
LIKELY BY AFTERNOON INTO THE EVENING...WITH POTENTIALLY MVFR BASES
DEVELOPING.
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE ON ALL FORECAST ELEMENTS.
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...CHANCE TSRA DURING A.M. THEN LIKELY DURING P.M.
PREVAILING VFR BUT LOCAL MVFR OR IFR WITH ANY TS.
MONDAY...SLIGHT CHANCE TSRA DURING A.M. OTHERWISE VFR THROUGH
THE DAY.
TUESDAY TROUGH THURSDAY...VFR. WX NIL.
MTF/TRS
&&
.MARINE...
205 AM CDT
HIGH PRESSURE PERSISTS OVER THE NORTHEAST U.S. WITH A LOW PRESSURE
TROUGH ACROSS THE PLAINS STATES EASING EASTWARD. SOUTHERLY FLOW WILL
CONTINUE BETWEEN THESE FEATURES ACROSS LAKE MICHIGAN THROUGH THE
DAY SUNDAY. WINDS SHOULD AGAIN TURN EASTERLY OFF THE ILLINOIS
NEARSHORE THIS AFTERNOON AS A LAKE BREEZE DEVELOPS...WHILE WINDS
ALONG THE INDIANA NEARSHORE MAY EVEN BACK TO NORTHEASTERLY FOR A
PERIOD THIS AFTERNOON. AS THE TROUGH SHIFTS EAST OVER THE LAKE BY
LATER SUNDAY...AND A LOW PRESSURE PROGRESSES NORTHEAST ALONG THE
BOUNDARY...WINDS WILL BEGIN TO VEER TOWARD THE WEST SUNDAY NIGHT.
RAIN WITH EMBEDDED THUNDER IS ALSO LIKELY ACROSS THE SOUTHERN HALF
OF THE LAKE BY LATER SUNDAY INTO SUNDAY EVENING. THE COOL AIR PUSH
BEHIND THIS TROUGH WILL NOT BE OVERLY STRONG...AND THUS EXPECT THE
WEST NORTHWEST FLOW TO BE ONLY AROUND 15 KT OR SO FOR MONDAY. HIGH
PRESSURE THEN LOOKS TO BE IN CONTROL FOR A TIME BEFORE WINDS
POTENTIALLY PICK UP LATER NEXT WEEK...ALTHOUGH UNCERTAINTY IS HIGH
AT THIS TIME.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1223 AM CDT SAT AUG 25 2012
.DISCUSSION...
324 PM CDT
TODAY THROUGH SATURDAY NIGHT...
AN UPPER LEVEL DISTURBANCE IS SLOWLY PASSING THROUGH NORTHERN
WISCONSIN AND WILL CONTINUE EASTWARD THROUGH THE NORTHERN GREAT
LAKES THIS EVENING. SOME OF THE SHORT TERM MODELS INDICATE
SCATTERED SHOWERS WILL DEVELOP ACROSS NORTHERN ILLINOIS...BUT WILL
CONTINUE WITH A DRY FORECAST THIS AFTERNOON. LATEST RAP ANALYSIS
INDICATES AMPLE CAPE AND LOW LEVEL LAPSE RATES NEAR DRY
ADIABATIC...HOWEVER SUSPECTING THE RAP ANALYSIS MAY BE OVER
ESTIMATING CAPE VALUES. ALSO TOOK INTO CONSIDERATION THAT THE UPPER
LEVEL WAVE IS WELL NORTH OF THE CWA...AND CONVECTION/SHOWERS OVER
LAKE MICHIGAN ARE ASSOCIATED WITH AN AREA OF 850 HPA WARM AIR
ADVECTION. SCT CU IS BEGINNING TO DEVELOP ROUGHLY ALONG THE I-55
CORRIDOR.
SKIES CLEAR TONIGHT AND EXPECTING A COMFORTABLE NIGHT DESPITE LOW
90S BEING REPORTED ACROSS THE CWA THIS AFTERNOON. OVERNIGHT LOWS
WILL BE IN THE MID 60S...EXCEPT FOR LOW 70S DOWNTOWN. SATURDAY WILL
BE MUCH LIKE TODAY...WITH A DRY AND HOT FORECAST. RAISED INHERITED
TEMPS SUCH THAT TOMORROWS HIGHS ARE A DEGREE OR TWO WARMER THAN
TODAY. COULD EVEN SEE AREAS IN THE SOUTHERN PORTIONS OF THE CWA
BEING A BIT WARMER THAN CURRENTLY FORECAST. MODEL SOUNDINGS
INDICATES THERE WILL BE PLENTY OF MIXING TOMORROW...THEREFORE WENT
WITH DEW POINTS SLIGHTLY LOWER THAN PREVIOUSLY FORECAST. MIN RH
VALUES WILL BE IN THE MID TO UPPER 20 PERCENT RANGE...BUT WITH LIGHT
WINDS FORECAST NOT ANTICIPATING ANY FIRE WEATHER HEADLINES. THAT
BEING SAID A FEW LOCATIONS MAY REACH RED FLAG CRITERIA...AS RFD DID
TODAY. KEPT PREVIOUS MIN TEMPS FOR SATURDAY NIGHT WITH MID TO UPPER
60S IN THE OUTLYING AREAS...AND IN THE LOW 70S DOWNTOWN.
SUNDAY THROUGH MONDAY NIGHT...
LOW PRESSURE CURRENTLY OVER SOUTHERN SASKATCHEWAN AND THE NORTHERN
GREAT PLAINS WILL MOVE EASTWARD ACROSS SOUTHERN CANADA THROUGH THE
WEEKEND. THE LOWS COLD FRONT PASSES THROUGH THE CWA LATE SUNDAY
NIGHT INTO MONDAY MORNING. PRECIP AHEAD OF THE COLD FRONT WAS THE
MAIN FORECAST CHALLENGE TODAY. THE NAM AND GFS LOOKED A BIT FAST
WHILE THE ECMWF HAS BEEN SLOWING THE PROGRESSION OF THE SHOWERS
AND THUNDERSTORMS THE PAST FEW RUNS. WENT WITH A NAM/ECMWF MIX
THAT WAS VERY SIMILAR TO THE PREVIOUS FORECASTS TIMING...WITH
PRECIP REACHING THE WESTERN EDGE OF THE CWA LATE SATURDAY NIGHT.
THAT BEING SAID...THE MODELS ARE INDICATING THE INITIAL UPPER
LEVEL VORTICITY STREAMER ASSOCIATED WITH FIRST WAVE OF PRECIP WILL
BE STRETCHED NORTH TO SOUTH AND FRACTURE SOMEWHERE OVER WISCONSIN.
THE SOUTHERN PART OF THE VORT STREAMER WILL THEN PROGRESS EASTWARD
BRINGING MUCH NEEDED RAIN TO NORTHERN ILLINOIS. CONFIDENCE IS
MEDIUM WITH THE TIMING AND PROGRESSION OF THE PRECIP...BUT HIGH
REGARDING THE POSSIBILITY OF IT BEING A SIGNIFICANT RAINFALL.
PW VALUES WILL BE AROUND TO SLIGHTLY ABOVE 2 INCHES AHEAD OF THE
FRONT...WHICH IS AROUND 2 STANDARD DEVIATIONS ABOVE NORMAL FOR
AUGUST. THEREFORE SUBSTANTIAL RAINFALL IS POSSIBLE AND AS MENTIONED
IN THE PREVIOUS DISCUSSION...TRAINING CELLS COULD CAUSE ISOLATED
WATER PROBLEMS.
TEMPS ON SUNDAY WILL BE MUCH COOLER WITH AREAS WEST OF I-55 IN THE
UPPER 70S...AND LOW TO MID 80S EXPECTED EAST OF I-55. TEMPS REBOUND
SLIGHTLY ON MONDAY WITH HIGHS IN THE LOW TO MID 80S.
EXTENDED...TUESDAY THROUGH FRIDAY...
HIGH PRESSURE MOVES IN BEHIND THE COLD FRONT LEADING TO ANOTHER
EXTENDED PERIOD OF DRY WEATHER. TEMPS INCREASE THROUGHOUT THE
EXTENDED...AND COULD BE EVEN WARMER THAN FORECAST. EXPECTING UPPER
80S TO QUITE POSSIBLY 90S BY LATE NEXT WEEK.
JEE
&&
.FIRE WEATHER...
428 PM CDT
RH VALUES DROPPED INTO THE 20 PERCENT RANGE ACROSS PARTS OF THE
AREA TODAY...AND SIMILAR CONDITIONS ARE EXPECTED TOMORROW.
TEMPERATURES TOMORROW WILL ONCE AGAIN BE IN THE LOW TO MID
90S...WITH LOWER DEW POINTS THAN TODAY. AMPLE MIXING WILL LIKELY
LEAD TO DEW POINTS DROPPING INTO THE LOW 50S SATURDAY AFTERNOON.
MIN RH VALUES WILL BE IN THE LOW TO MID 20 PERCENT RANGE...HOWEVER
WIND SPEEDS WILL BE AROUND 10 MPH. WIND GUSTS WILL DEVELOP IN THE
AFTERNOON WITH GUSTS UP TO 20 MPH EXPECTED WEST OF I-39...AND
GUSTS AROUND 15 MPH EXPECTED EAST OF I-39. FUEL MOISTURE LEVELS
ARE ABOVE 10 PERCENT FOR MUCH OF NORTHERN ILLINOIS...WHILE AREAS
EAST OF I-55 HAVE 10-HOUR FUELS LESS THAN 10 PERCENT. THEREFORE
TWO OF THE THREE RED FLAG CONDITIONS MAY BE MET IN ISOLATED
LOCATIONS...SIMILAR TO TODAY...BUT NOT EXPECTING ALL THREE RED
FLAG CONDITIONS TO BE MET. THEREFORE NO FIRE WEATHER HEADLINES ARE
ANTICIPATED.
A COLD FRONT MOVES THROUGH THE REGION LATE SATURDAY NIGHT INTO
SUNDAY BRINGING A WIDESPREAD SOAKING RAIN AND COOLER TEMPERATURES
WITH IT.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* SPORADIC GUSTS TO 15 KT THIS AFTERNOON.
//DISCUSSION...UPDATED 06Z...
HIGH PRESSURE WILL REMAIN IN CONTROL TO THE EAST OF THE REGION
TODAY WITH LOW PRESSURE BECOMING BETTER ORGANIZED ACROSS THE
CENTRAL PLAINS. WITH SUCH A PATTERN...SOUTHERLY WINDS WILL PREVAIL
AND SHOULD BE AT A SIMILAR MAGNITUDE TO THOSE SEEN ON FRIDAY. A
FEW HIGH BASED CU ARE POSSIBLE...AND ANY LAKE BREEZE IS
ANTICIPATED TO REMAIN TO THE EAST OF ORD AND MDW. AS THE LOW
PRESSURE TROUGH INCHES EAST TONIGHT...UPPER LEVEL CLOUDS WILL BE
ON THE INCREASE. THESE CLOUDS WILL LOWER ON SUNDAY WITH RAIN
LIKELY BY AFTERNOON INTO THE EVENING...WITH POTENTIALLY MVFR BASES
DEVELOPING.
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE ON ALL FORECAST ELEMENTS.
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...CHANCE TSRA DURING A.M. THEN LIKELY DURING P.M.
PREVAILING VFR BUT LOCAL MVFR OR IFR WITH ANY TS.
MONDAY...SLIGHT CHANCE TSRA DURING A.M. OTHERWISE VFR THROUGH
THE DAY.
TUESDAY TROUGH THURSDAY...VFR. WX NIL.
MTF/TRS
&&
.MARINE...
219 PM CDT
PATTERN REMAINS LARGELY UNCHANGED TODAY AND WILL CONTINUE TO PERSIST
THROUGH MUCH OF THE WEEKEND AS HIGH PRESSURE REMAINS ANCHORED OVER
THE EASTERN STATES AND LOW PRESSURE PERSISTS OVER THE CANADIAN
PRAIRIES. SOUTHERLY FLOW WILL CONTINUE ACROSS LAKE MICHIGAN UNTIL
LATE SUNDAY. THROUGH SUNDAY NIGHT...THE LOW PRESSURE IS FORECAST TO
DEEPEN AS IT LIFTS NORTHEAST TOWARDS HUDSON BAY...AND A TRAILING
COLD FRONT IS EXPECTED TO MOVE ACROSS LAKE MICHIGAN LATE SUNDAY
NIGHT INTO MONDAY TURNING WINDS TO THE WEST OR NORTHWEST. HIGH
PRESSURE WILL THEN BUILD ACROSS THE PLAINS STATES AND MOVE
EAST...BECOMING CENTERED JUST SOUTH OF THE GREAT LAKES REGION. THE
WINDS WILL BE LIGHT OVER THE SOUTHERN HALF OF THE LAKE CLOSE TO THE
HIGH CENTER...BUT THE NORTH HALF OF THE LAKE WILL SEE SLIGHTLY
WINDIER CONDITIONS AS ANOTHER AREA OF LOW PRESSURE DEVELOPS ACROSS
THE CANADIAN PRAIRIES AND A MODEST PRESSURE GRADIENT DEVELOPS OVER
NORTHERN LAKE MICHIGAN. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAY ME
231 AM EDT SAT AUG 25 2012
.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER NORTHERN NEW ENGLAND AND THEN SHIFT
OFFSHORE THIS WEEKEND. GENERALLY DRY AND SEASONABLY WARM
CONDITIONS ARE EXPECTED THROUGH EARLY NEXT WEEK BEFORE A COLD
FRONT MOVES THROUGH LATE TUESDAY OR EARLY WEDNESDAY.
&&
.NEAR TERM /THROUGH TODAY/...
A COUPLE CHALLENGES TO THE FCST ONCE AGAIN THIS MORNING. AFTER
MORNING FOG MIXES OUT...HIGH CLOUDS WITH A FEW EMBEDDED AC WILL
CONTINUE TO RIDE INTO THE RIDGE POSITIONED OVER NEW ENGLAND AND
OFF THE EASTERN SEABOARD. THIS MAY LIMIT TEMPS OVER SOUTHERN ME/NH
BY A FEW DEGS DURING THE AFTN HOURS. OTHERWISE...PARTLY TO MOSTLY
SUNNY CONDITIONS WILL PREVAIL NORTH OF THIS REGION THIS MORNING.
DURING THE AFTN...SUFFICIENT ENOUGH INSTABILITY WILL ALLOW FOR A
SMALL CHANCE FOR A BRIEF SHOWER OVER WRN NH AND THE WRN MTNS OF
MAINE IN THE PROXIMITY AROUND THE PERIPHERY OF THE SURFACE RIDGE.
WITH LI VALUES DROPPING IN THIS AREA AND AMPLE SFC HEATING...THERE
IS ALSO A RISK OF A TSTM IN THIS REGION. LATEST HRRR MODEL CONTS
TO PICK UP ON THIS WIDELY SCT AFTN PCPN.
USED A BLEND OF MAV/MET MOS FOR AFTN MAX TEMPS. AFTN SEA BREEZES
WILL KEEP THE COASTLINE COOLER ONCE AGAIN.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM SUNDAY/...
MORE PATCHY FOG WILL DEVELOP TONIGHT...DESPITE MORE HIGH THIN
CLOUDINESS CROSSING OVER SRN ME/NH. ONCE AGAIN...SOME MID AND
UPPER 40S PSBL FOR OVERNIGHT LOWS IN THE MTNS.
A REPEAT PERFORMANCE OCCURS ON SUNDAY. STILL THE POSSIBILITY
EXISTS FOR A BRIEF SHOWER OR TSTM OVER NH AND THE WRN MTNS OF ME.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
THE LARGE BROAD SURFACE AND UPPER RIDGE WILL MOVE OFF THE COAST
AND ALLOW A RETURN SSWLY FLOW EARLY NEXT WEEK. TEMPS WILL BE MILD
AND DEWPOINTS WILL BE ON THE RISE EARLY NEXT WEEK WITH CONDITIONS
POSSIBLY BECOMING RATHER MUGGY. BY LATE MON AND TUE THE UPPER
RIDGE BREAKS DOWN ALLOWING AN UPPER TROF TO APPROACH THE AREA FROM
THE WEST SETTING OFF SHWRS/TSTMS LATE MON AND MON NIGHT WITH SCT
SHWRS TUES. A SFC CDFNT ASSOC WITH THE UPPER TROF WILL MOVE THRU
BY LATE TUES OR EARLY WED BRINGING WITH IT A MUCH DRIER CANADIAN
AMS AND COOLER TEMPS FOR THE MID TO LATTER PART OF THE WEEK.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM...VFR CONDITIONS WILL PREVAIL ACROSS THE REGION
THROUGHOUT THE PERIOD. SOME VALLEY FOG MAY DEVELOP TONIGHT OVER
FAVORED LOCATIONS RESULTING IN A FEW HOURS OF IFR/LIFR CONDITIONS
BEFORE BURNING OFF EARLY TOMORROW MORNING.
LONG TERM...GENERALLY VFR EXCEPT SHOWERS AND THUNDERSTORMS
POSSIBLE MONDAY AFTERNOON AND MONDAY NIGHT ALLOWING MVFR CONDS TO
DEVELOP...THEN A CHC OF SHWRS TUESDAY.
&&
.MARINE...
SHORT TERM...NO FLAGS EXPECTED
LONG TERM...GENERALLY LIGHT FLOW OVER THE WATERS CONTINUES. COLD
FRONT MOVES THROUGH TUESDAY.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
130 AM EDT SAT AUG 25 2012
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 348 PM EDT FRI AUG 24 2012
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A GENERAL ZONAL
FLOW OVER THE NRN TIER CONUS/SRN CANADA. A SHRTWV EMBEDDED IN THIS
FLOW IS PRESENT OVER WI/UPR MI EARLY THIS AFTN AND HAS BEEN
SUPPORTING SOME ISOLD -SHRA/A FEW TS OVER MAINLY THE E HALF OF THE
CWA DESPITE PRESENCE OF DRY LLVL AIR SHOWN ON THE 12Z GRB/APX RAOBS
THAT EXTENDS WELL TO THE S AS DEPICTED ON THE 12Z RAOB FM QUAD
CITIES IOWA. OVER THE W HALF...NVA IN THE WAKE OF THE SHRTWV AND
AGGRESSIVE DRYING FOCUSED AT H5-7 WITH ENEWD SPREAD OF AIRMASS SHOWN
ON THE 12Z MPX RAOB HAS SUPPRESSED SHRA AND RESULTED IN SOME CLRG IN
DESPITE PERSISTENCE OF AXIS OF HIER H85 DEWPTS/THETA-E IN THAT AREA
PER RUC ANALYSIS. SHRTWV RDG AXIS OVER MN IS BRINGING DRY WX THERE
ALONG WITH MOCLR SKIES...BUT MORE CLDS AND SOME SHRA/TS ARE OVER THE
NRN PLAINS IN ADVANCE OF POTENT SHRTWV MOVING EWD THRU SRN ALBERTA.
LATE THIS AFTN...DESPITE NVA/AGGRESSIVE UPR DRYING IN THE WAKE OF
SLOW MOVING SHRTWV...SUSPECT SOME SHRA/TS MAY DVLP ON THE LEADING
EDGE OF THE H5-7 DRYING WHERE MORE INSOLATION WL COINCIDE WITH AREA
OF HIER H85 DEWPTS. A NUMBER OF THE RECENT HIER RES MODELS SHOW AT
LEAST ISOLD-SCT SHRA/TS DVLPG OVER THE CENTRAL ZNS...SO PAINTED AN
AXIS OF SOMEWHAT HIER CHC POPS IN THIS AREA. THE FAR W SHOULD BE DRY
UNDER MUCH DRIER H7-5 AIR AND WITH SOME MODERATION NEAR LK SUP.
LINGERING LLVL DRY AIR OVER THE E SHOULD ALSO LIMIT POPS IN THAT
AREA DESPITE MORE MID LVL MSTR THAT MIGHT SUPPORT PERSISTENT -SHRA.
TNGT...AS DEEPER SHRTWV OVER SW CANADA THIS MRNG DRIFTS EWD AND
SHRTWV OVER THE AREA SHIFTS TO THE E...ARRIVAL OF SHRTWV RDG FM MN/
ASSOCIATED H5 RISES IN CONCERT WITH LOSS OF DAYTIME HEATING SHOULD
CAUSE ANY EVNG SHRA/TS OVER MAINLY THE E AND CENTRAL ZNS TO
DISSIPATE. PCPN CHCS WL LINGER LONGEST OVER THE E CLOSER TO
DEPARTING SHRTWV/WHERE MID LVL MSTR REMAINS MOST ABUNDANT LONGEST.
ALTHOUGH THERE WAS QUITE A BIT OF FOG LAST NGT OVER MN...THE 12Z
NAM/LOCAL WRF-ARW SHOW PERSISTENT SSW LLVL FLOW DRAWING DRIER AIR
SHOWN ON THE 12Z GRB/QUAD CITY RAOBS INTO THE FA. SO EXPECT NO FOG
TO IMPACT THE CWA. DESPITE THE DRYING COLUMN...STEADY S WIND SHOULD
LIMIT THE DIURNAL TEMP FALL AT MOST SPOTS...FURTHER LIMITING THE
POTENTIAL FOR FOG.
SAT...FOCUS TURNS TO HOW QUICKLY STRONG DISTURBANCE OVER SW CANADA
THIS MRNG MIGHT INFLUENCE THE WX ESPECIALLY OVER THE WRN CWA. THE
DAY SHOULD AT LEAST START MOSUNNY WITH SHRTWV RDG AXIS/DRY H85-5
AIRMASS OVHD. BY 00Z SUN...THE SHRTWV IS PROGGED TO DRIFT NEWD TO
NEAR LK WINNIPEG AND BECOME OCCLUDED WITH H5 CUTOFF NEARLY OVER
992MB SFC LO. SINCE LLVL SLY FLOW IS FCST TO ADVECT THE DRIER
SFC-H85 AIR NOTED TO THE S OVER THE CWA THRU THE DAY AND BULK OF
DEEP LYR QVECTOR CNVGC OVER WARM CONVEYOR BELT MSTR/ATTENDANT SFC
COLD FNT ARE PROGGED TO RACH ONLY THE FAR W BY 00Z SUN...OPTED TO
SLOW DOWN EWD PUSH OF ACCOMPANYING POPS. GIVEN THE STRENGTH OF THE
SHRTWV TO THE W...PREFER THE HIER H85 FCST TEMPS BY THE NAM...WHICH
SHOWS THIS TEMP REACHING 20C OVER THE CWA VERSUS ONLY 17C BY THE
GFS. DEEP MIXING ON THE NAM FCST SDNGS YIELDS HI TEMPS REACHING ARND
90. MAX TEMPS WL BE HIEST NEAR LK SUP WHERE SLY FLOW DOWNSLOPES AND
LIMITS AND MODERATION OFF LK SUP. IN FACT...SOME RECORD HI TEMPS MAY
FALL ON SAT. AREAS DOWNWIND OF LK MI WL BE COOLEST. WITH SFC DEWPTS
LIKELY TO MIX OUT TO ARND 50 AWAY FM LK MODERATION...MIN RH WL DIP
AS LO AS 25 PCT IN THE PRESENCE OF WIND GUSTS TO 20-25 MPH ENHANCED
BY THE MIXING. FORTUNATELY...RECENT RAINS HAVE MOISTENED THE GROUND
SUFFICIENTLY TO MINIMIZE ANY FIRE WX IMPACTS.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 348 PM EDT FRI AUG 24 2012
AN UPPER-LEVEL TROUGH AND SLOW-MOVING COLD FRONT WILL CONTINUE TO
BRING RAIN AND THUNDERSTORM CHANCES TO UPPER MI THROUGH MONDAY
BEFORE DRY AND WARMER WEATHER RETURNS UNDER HIGH PRESSURE FOR THE
MIDDLE OF THE WEEK.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...A SHARP TROUGH CURRENTLY
MOVING THROUGH ALBERTA AND NORTHERN MT WILL SHIFT EAST THROUGH
SATURDAY AND INDUCE A STRONG SFC LOW OVER SOUTHERN SASKATCHEWAN. BY
SATURDAY NIGHT...THE TROUGH WILL BE LIFTING TO THE NORTHEAST THROUGH
MANITOBA WHILE BECOMING NEARLY STACKED WITH THE ASSOCIATED SFC LOW.
A COLD FRONT EXTENDING FROM A NEW OCCLUSION OVER WESTERN ONTARIO
WILL BE SURGING EASTWARD THROUGH MN SATURDAY AFTERNOON. THERE IS
VERY GOOD MODEL AGREEMENT THAT THIS COLD FRONT WILL REACH THE
WESTERN TIP OF THE CWA BY 06Z SUNDAY...THEN WASH OUT ACROSS THE
CENTRAL CWA BY SUNDAY AFTERNOON AS IT LOSES SUPPORT FROM THE
WEAKENING STACKED LOW. A SECONDARY SFC TROUGH WILL THEN CATCH UP TO
THE FRONT AND HELP KICK IT OUT OF THE CWA BY SUNDAY EVENING.
NOT TOO CONFIDENT ON WIDESPREAD PRECIP CHANCES ATTM FOR SEVERAL
REASONS. FIRST...BEST Q-VECTOR CONVERGENCE WILL EXIST NORTH CLOSER
TO THE MID-LEVEL LOW...AND SOUTH WHERE A SHORTWAVE TROUGH WILL BE
MOVING INTO THE MID-MS VALLEY FROM THE SOUTHERN PLAINS. NEXT...THE
SFC LOW FORMING IN RESPONSE TO THE SOUTHERN PLAINS TROUGH WILL
LIKELY CUTOFF A SIGNIFICANT PORTION OF THE MOISTURE SUPPLY AHEAD OF
THE FRONT. THUS...APPRECIABLE MOISTURE WILL BE CONFINED TO THE NEAR
SFC LAYER OVER UPPER MI. ANY PRECIP THAT FORMS WILL BE FORCED BY A
BAND OF H8-H7 FRONTOGENESIS ALONG THE FRONT...THOUGH MOISTURE WILL
BE LACKING IN THIS LAYER. CUT BACK POPS TO LOW CHANCE FOR MUCH OF
THE LAND...WITH HIGHER POPS OVER THE WESTERN LAKE AS IT WILL BE
CLOSER TO BETTER FORCING FROM THE LOW. SOME SFC HEATING WILL AID
DEVELOPMENT OF NEW SHOWERS AND THUNDERSTORMS IN THE AFTERNOON ACROSS
THE EAST HALF...BUT ONCE AGAIN...A LACK OF MOISTURE WILL STILL BE A
CONCERN.
INCREASED/DECREASED HIGHS IN THE WEST/EAST FOR SUNDAY TO ACCOUNT FOR
CLOUD AND PRECIP TRENDS. EXPECTATION IS THAT CLOUDS WILL QUICKLY
CLEAR WEST IN THE MORNING. H8 TEMPS WILL COOL TO AROUND 14C WITH
THIS CLEARING...BUT SHOULD STILL BE WARM ENOUGH TO PRODUCE LOW 80S
FOR HIGHS. PATCHY FOG COULD BE POSSIBLE FOR THE INTERIOR WEST SUNDAY
NIGHT...BUT DRY AIR ADVECTING INTO THE AREA SHOULD BE ENOUGH TO
SUBDUE THE THREAT.
MONDAY AND MONDAY NIGHT...AS THE MID-LEVEL LOW DRIFTS NORTHEASTWARD
TO HUDSON BAY SUNDAY NIGHT...IT WILL TAP INTO SOME ENERGY FROM THE
RAGGED POLAR VORTEX OVER NORTHERN NUNAVUT. THE REINFORCED TROUGH AND
WEAK SFC TROUGH ARE THEN PROGGED TO AFFECT THE AREA MONDAY NIGHT.
MODELS BEGIN TO DIVERGE SIGNIFICANTLY BY THIS POINT...BUT VERY
LITTLE MOISTURE ABOVE THE SFC MIXED LAYER WILL LIKELY PREVENT ANY
PRECIP. EVEN MORE...DO NOT EXPECT MUCH CLOUD COVER EXCEPT FOR
POSSIBLE AFTERNOON CUMULUS. HIGHS WILL BE IN THE 70S...WITH THE
COOLEST TEMPS NORTH CLOSER TO A H8 TEMP MIN IN NORTHERN ONTARIO.
TUESDAY THROUGH THURSDAY...A VERY IMPRESSIVE RIDGE WILL SLOWLY EDGE
INTO THE UPPER GREAT LAKES BEGINNING TUESDAY...WITH THE SFC HIGH
PRESSURE CENTERING ITSELF OVER WI/UPPER MI BY WEDNESDAY MORNING. THE
HIGH WILL CONTINUE TO GRADUALLY DRIFT SOUTHEASTWARD WEDNESDAY
THROUGH THURSDAY...WITH UPPER MI REMAINING UNDER ITS INFLUENCE.
INCREASED HIGHS THROUGH FRIDAY AS THERE WILL BE PLENTY OF SUN AND
WARM H8 TEMPS. ISENTROPIC LIFT ON THE 305-310 THEATA SFCS IN
ADDITION TO H8 MOISTURE TRANSPORT MAY RESULT IN A FEW SHOWERS AND
THUNDERSTORMS WEDNESDAY NIGHT...MAINLY NORTH.
FRIDAY...THERE IS MODEL AGREEMENT THAT THE RIDGE WILL BEGIN TO BREAK
DOWN BY EARLY FRIDAY. THE GFS IS ONCE AGAIN MORE AGGRESSIVE THAN THE
ECMWF WITH A TROUGH FROM BRITISH COLUMBIA MOVING INTO THE RIDGE. IT
IS DIFFICULT TO SAY WHICH MODEL WILL PAN OUT...IF EITHER...SO WILL
GO WITH A MODEL CONSENSUS FOR THE FORECAST.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 129 AM EDT SAT AUG 25 2012
EXPECT VFR CONDITIONS AT ALL 3 SITES THRU THIS FCST PERIOD WITH
RELATIVELY DRY LLVL AIR IN PLACE. DID PUT IN SOME LLWS IN IWD
OVERNIGHT. NEXT SYSTEM BEGINS TO AFFECT IWD IN THE EVENING WITH PCPN
HOLDING OFF UNTIL REALLY LATE IN THE PERIOD. CONFIDENCE LOW RIGHT
NOW TO PUT IN TIMING OF PCPN AT KIWD AS MOISTURE STILL REMAINS TO
THE WEST OF THE AREA.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 348 PM EDT FRI AUG 24 2012
EXCEPT FOR A STRONGER S WIND UP TO 25 KTS OVER THE E INTO THIS
EVENING AHEAD OF AN APPROACHING LO PRES TROF...WINDS THRU THE
FORECAST PERIOD WILL BE NO HIER THAN 20 KTS AS THE COMBINATION OF A
WEAK PRES GRADIENT AND HIER OVERWATER STABILITY LIMIT WIND SPEEDS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TK
AVIATION...GM/RJT
MARINE...KC
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
341 AM EDT SAT AUG 25 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE SLOWLY UP THE CAROLINA COAST OVERNIGHT.
HIGH PRESSURE WILL BUILD SOUTH THROUGH SUNDAY...BRINGING SLIGHTLY
DRIER AIR INTO THE REGION. TROPICAL STORM ISAAC IS EXPECTED TO
MOVE INTO THE EASTERN GULF OF MEXICO EARLY NEXT WEEK. REMNANTS OF
ISAAC COULD BRING UNSETTLED WEATHER TO THE CAROLINAS BY THE MIDDLE
OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 10:30 PM FRIDAY...ISOLATED SHOWERS CONTINUE WELL INLAND AND
JUST OFFSHORE...WHICH APPEAR TO BE SPINNING AROUND THE PERIPHERY
OF AN UPPER LOW. THESE SHOULD GRADUALLY FADE AS DRYER AIR WORKS IN
OVERNIGHT. PREVIOUS DISCUSSIONS FOLLOW:
LOOKS LIKE WE HAVE FINALLY BROKEN OUR STREAK OF CONSECUTIVE DAYS
AT 70F OR ABOVE...DATING BACK TO JUNE 28TH. THIS WAS A RECORD
STRING OF 56 DAYS. THE PREVIOUS RECORD WAS SET IN 1941 WITH 52
CONSECUTIVE DAYS.
MID TO UPPER LOW WILL TRACK UP THE SOUTHEAST COAST THROUGH
TONIGHT. THE H5 CIRCULATION REMAINS BROAD WITH CENTER TIGHTENING A
BIT OVERNIGHT WITH CENTER FORECAST OVER NC/VA BORDER BY SAT
MORNING. THE ASSOCIATED SURFACE LOW JUST E-SE OF CAPE FEAR THIS
AFTERNOON WILL MOVE NORTH AND BECOME MORE ELONGATED AS IT WEAKENS
THROUGH TONIGHT. NAM STILL SHOWING BEST ENERGY ASSOCIATED WITH
THIS LOW TO MOVE FROM COASTAL WATERS JUST SOUTH OF CAPE FEAR DUE
NORTH INTO NC THIS AFTERNOON. HRRR MODEL SHOWING BEST CHC FOR
HEAVIER PCP FROM THE TIP OF CAPE FEAR NORTH ALONG THE NORTH
CAROLINA COAST MAINLY FROM NEW HANOVER COUNTY THROUGH PENDER
COUNTY. THE BEST CHC OF HEAVIER PCP WILL OCCUR DURING THIS TIME
BUT BULLSEYE FOR HEAVIEST RAIN IN TSTMS WILL REMAIN OVER THE
WATERS TO THE EAST. THE GREATEST THREAT THROUGH WILL BE POTENTIAL
FOR FLOODING AS STEERING FLOW OVER MOST LAND AREAS WILL REMAIN
VERY WEAK. PCP WATER VALUES WILL REMAIN AROUND 2 INCHES UP THE
CAPE FEAR COAST DROPPING OFF AS YOU MOVE INLAND DOWN LESS THAN AN
INCH IN DRIER AIR AND SUBSIDENCE ON BACK END OF LOW WEST OF LOCAL
CWA...OVER CENTRAL TO WESTERN CAROLINAS. WILL KEEP LOW END POPS
INLAND AS SOME ENERGY ROTATES AROUND THE LOW...BUT OVERALL CLOUDS
AND COOLER NORTHERLY FLOW KEEPING TEMPS JUST AROUND 80 AND OVERALL
MORE STABLE ATMOSPHERE.
MODEL SOUNDINGS AND MOISTURE PROFILES SHOWING DRIER AIR WORKING
ITS WAY IN ON THE BACK EDGE OF LOW THROUGH THE MID TO UPPER
LEVELS TONIGHT AS IT LIFTS OFF TO THE NORTH. THIS WILL HELP PCP
SHUT OFF OVER LOCAL AREA. NAM SHOWS PCP WATER VALUES DROPPING
DOWN LESS THAN 1.5 INCHES BY SAT MORNING. CLOUDS...PCP AND FOG
WILL HELP KEEP TEMPS IN THE MID 60S AND CLOSER TO 70 WHERE GREATER
DEWPOINT AIR WILL HANG ON THE LATEST. MAY SEE STRATUS DEVELOP AS
MOISTURE BECOMES TRAPPED UNDER LOW LEVEL INVERSION...MORE PROBABLE
CLOSER TO THE COAST.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...EXITING MID LEVEL TROUGH/LOW SUN LEAVES WEAK
5H RIDGING BEHIND WHILE AT THE SURFACE HIGH PRESSURE CONTINUES TO
EXTEND SOUTH ACROSS THE PIEDMONT. DEEP DRY AIR IN PLACE SUN WILL
LIMIT DEPTH OF CONVECTION...THOUGH HEATING WILL YIELD A FAIRLY
SIGNIFICANT FLAT CU FIELD. SUN NIGHT INTO MON BECOMES PROBLEMATIC AS
THE TRACK OF ISAAC WILL PLAY SIGNIFICANT ROLE IN HOW MUCH AND HOW
QUICKLY THE LARGE PLUME OF TROPICAL MOISTURE ASSOCIATED WITH THE
STORM REACHES THE AREA.
A LOOK AT FORECAST SOUNDINGS SEVERAL DIFFERENT MODELS SHOWS DEEP
MOISTURE IN PLACE ON MON...PRECIPITABLE WATER VALUES REACH 2 INCHES
ACROSS MUCH OF THE AREA...AND LOW LEVEL CONVERGENCE ALONG THE COAST
COMBINED WITH THE DEEP MOISTURE SHOULD PRODUCE CONVECTION EARLY MON.
DIURNAL INSTABILITY COMBINED WITH WEAK LOW LEVEL CONVERGENCE WILL
HELP CONVECTION SPREAD INLAND...BUT LIMITED DYNAMICAL SUPPORT WILL
KEEP ACTIVITY AWAY FROM THE IMMEDIATE COAST LIMITED TO THE
AFTERNOON/EVENING HOURS MON. THINK CONVECTION OVER THE WATERS WILL
CONTINUE MON NIGHT WITH FLOW PUSHING ANY ACTIVITY ONSHORE...WHERE IT
WILL DISSIPATE.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 3 AM SATURDAY...LONG TERM FORECAST REMAINS QUITE CHALLENGING
WITH ISAAC PLAYING A SIGNIFICANT ROLE. THE LACK OF A CLEAR TRACK ONCE
THE STORM MAKES LANDFALL LEADS TO LOW CONFIDENCE IN THE WED THROUGH
FRI FORECAST. DEEP TROPICAL MOISTURE AND WEAK DIVERGENCE ALOFT
ENHANCING INCREASING LOW LEVEL DIVERGENCE WILL LEAD TO AN INCREASE
IN PRECIP COVERAGE TUE INTO TUE NIGHT. IT IS AT THIS POINT WHERE
FORECAST BECOMES LESS CLEAR. THE 00Z RUN OF THE GFS HAS DONE NOTHING
TO INCREASE CONFIDENCE. THE CAUSE OF THIS IS 2 5H RIDGES...ON TO THE
NORTHWEST AND ONE TO THE EAST/SOUTHEAST...WHICH FORM A BLOCKING
PATTERN. THE ECMWF SOLUTION HAS BEEN TO SHOW THE 5H RIDGE OVER THE
CENTRAL US BREAKING DOWN WHILE A MAJORITY OF THE GFS SOLUTIONS HAVE
HELD THIS PORTION OF THE BLOCK STRONG. BLOCK PATTERN ARE NOTORIOUS
FOR GIVING GUIDANCE FITS AND HAVE A FEELING THE ULTIMATE SOLUTION
WILL REMAIN CLOUDED FOR THE NEXT FEW DAYS. AS THE INHERITED FORECAST
IS A GOOD COMPROMISE BETWEEN THE SOLUTIONS...WITH A SLIGHT LEAN IN
FAVOR OF THE GFS...CANNOT SEE ANY REASON TO DEVIATE UNTIL THE TRACK
OF ISAAC AND ITS REMNANTS BECOMES CLEARER. THUS ONLY SIGNIFICANT
CHANGES WILL BE SLIGHT UPWARD ADJUSTMENT TO POP LATE IN THE PERIOD.
HIGHS WILL BE WITHIN A COUPLE DEGREES OF CLIMO THROUGH THE
PERIOD...WITH LOWS HELD A BIT ABOVE CLIMO BY CLOUD COVER AND LOW
LEVEL WINDS.
&&
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
AS OF 06Z...A CLOSED MID-LEVEL LOW HAS MANIFESTED ITSELF ACROSS THE
ILM CWA THIS EARLY AM. DYNAMICS ASSOCIATED WITH THE LOW ALONG WITH
THE COLD POOL ALOFT...WILL BOTH COMBINE TO PRODUCE VCSH OR POSSIBLY
A SHORT PERIOD OF PREDOMINATE R- OR R DURING THE PRE-DAWN HRS ACROSS
MAINLY INLAND PORTIONS OF THE ILM CWA...EXTENDING FROM LBT TO
POSSIBLY FLO. WILL GO WITH THE MORE OPTIMISTIC FORECAST AND SAY THE
COLD POOL/CLOSED LOW LIFTS FAR ENOUGH NORTH OF THE AREA TODAY. THIS
WILL ALLOW DRIER AIR TO INFILTRATE THE ILM CWA...AS SEEN WITH THE
LATEST WATER VAPOR IMAGERY TRENDS. LOOK FOR VFR CONDITIONS BY
14Z-16Z...WHICH WILL CONTINUE FOR THE REMAINDER OF THE FORECAST
PERIOD. FOR THE COASTAL TERMINALS...A WEAK N TO NE SFC WIND AROUND 5
KT EARLY THIS AFTERNOON WILL VEER TO THE E-SE THIS AFTERNOON DUE TO
A WEAK RESULTANT WIND OR WEAK SEA BREEZE. ANY CLOUDINESS LEFT THIS
AFTERNOON WILL LIKELY DISSIPATE OR FADE AWAY LEAVING A MOSTLY CLEAR
SKY TO START THE OVERNITE PERIOD.
EXTENDED OUTLOOK...ISOLATED SHRA/TSRA MON. BETTER CHANCE OF SHOWERS
AND STORMS TUESDAY AND WEDNESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 10:30 PM FRIDAY...LATEST OBS SHOW WINDS ARE SETTLING INTO A
NORTHWESTERLY FLOW...WITH WINDS NOW IN THE 10 TO 15 KT
RANGE...HIGHEST NORTH. SEAS RANGE FROM 2 TO 4 FT. NO CHANGES TO
THE GOING FORECAST...PREVIOUS DISCUSSION FOLLOWS:
SFC WINDS OF AROUND 15 KTS WILL DIMINISH A BIT OVERNIGHT AS THEY
BACK TOWARD THE NW. THIS OFF-SHORE FLOW WILL ACT TO LOWER SEAS BUT
A LONGER PERIOD E-SE SWELL UP TO 16 SECONDS WILL COUNTERACT THIS
OFF SHORE FLOW AND WILL PRODUCE A SLIGHT INCREASE IN OVERALL SEAS
OVERNIGHT. SEAS WILL BUILD TO 3 TO 4 FT MAINLY ACROSS THE OUTER
WATERS. EXPECT ROUGHER SEAS WITH HIGHER WINDS AND SEAS IN TSTMS
THROUGH THIS EVENING AND ALSO REDUCED VSBYS DUE TO HEAVY RAIN.
RADAR CONTINUED TO SHOW THE POSSIBILITY OF WATERSPOUTS IN STORMS
OVER THE OUTER COASTAL WATERS THIS AFTERNOON.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...NORTHERLY FLOW AROUND EAST SIDE OF INLAND HIGH
PRESSURE SUN WILL VEER TO EASTERLY SUN NIGHT INTO MON. REMAINS OF
STALLED FRONT/COASTAL TROUGH MOVE ONSHORE MON WITH SOUTHEAST FLOW
DEVELOPING OVER THE WATERS. AT THIS POINT IT APPEARS ANY IMPACT FROM
ISAAC THROUGH THE END OF THE PERIOD WOULD BE LIMITED. GRADIENT
REMAINS MORE OR LESS STATIC THROUGH THE PERIOD WITH WINDS GENERALLY
ON THE LOW SIDE OF THE 10 TO 15 KT RANGE. SEAS 3 TO 5 FT THROUGH THE
PERIOD...A MIX OF NORTHEAST TO EAST WIND WAVE AND SOUTHEAST SWELL.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 AM SATURDAY...POST LANDFALL TRACK OF ISAAC WILL PLAY A
SIGNIFICANT ROLL IN DETERMINING THE WIND FIELD LATE IN THE PERIOD.
SOUTHERLY FLOW IS ANTICIPATED TUE WITH ISAAC TRACKING WEST OF
FL...EVENTUALLY MAKING LANDFALL LATER TUE ON THE FL PANHANDLE.
GRADIENT BETWEEN ISAAC AND BERMUDA HIGH WILL PRODUCE SOUTHEAST FLOW
IN THE 10 TO 15 KT RANGE. WHILE SOUTHERLY FLOW SHOULD CONTINUE ON
WED...THE TRACK OF ISAAC WILL BE A SIGNIFICANT FACTOR IN DETERMINING
HOW STRONG THE SOUTHERLY FLOW OVER THE WATERS WILL BE. CURRENT
FORECAST IS 15 TO 20 KT WED BUT HAVE LOW CONFIDENCE IN THE TRACK OF
ISAAC AFTER IT MOVES INTO SOUTHERN AL/GA. IT IS QUITE POSSIBLE WINDS
COULD END UP HIGHER BY 10 OR 15 KT...ESPECIALLY ACROSS SC WATERS
LATE WED. THIS UNCERTAINTY ALSO TRANSLATES INTO THE SEAS FORECAST
FOR WED...WHERE HEIGHTS COULD CREEP CLOSE TO DOUBLE DIGITS LATE IN
THE PERIOD IF THE MORE PESSIMISTIC FORECAST VERIFIES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...REK/RGZ
SHORT TERM...III
LONG TERM...III
AVIATION...DCH/43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
140 AM EDT SAT AUG 25 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE SLOWLY UP THE CAROLINA COAST OVERNIGHT.
HIGH PRESSURE WILL BUILD SOUTH THIS WEEKEND...BRINGING SLIGHTLY
DRIER AIR INTO THE REGION. TROPICAL STORM ISAAC IS EXPECTED TO
MOVE INTO THE EASTERN GULF OF MEXICO EARLY NEXT WEEK. REMNANTS
OF ISAAC COULD BRING UNSETTLED WEATHER TO THE CAROLINAS BY THE
MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 10:30 PM FRIDAY...ISOLATED SHOWERS CONTINUE WELL INLAND AND
JUST OFFSHORE...WHICH APPEAR TO BE SPINNING AROUND THE PERIPHERY
OF AN UPPER LOW. THESE SHOULD GRADUALLY FADE AS DRYER AIR WORKS IN
OVERNIGHT. PREVIOUS DISCUSSIONS FOLLOW:
LOOKS LIKE WE HAVE FINALLY BROKEN OUR STREAK OF CONSECUTIVE DAYS
AT 70F OR ABOVE...DATING BACK TO JUNE 28TH. THIS WAS A RECORD
STRING OF 56 DAYS. THE PREVIOUS RECORD WAS SET IN 1941 WITH 52
CONSECUTIVE DAYS.
MID TO UPPER LOW WILL TRACK UP THE SOUTHEAST COAST THROUGH
TONIGHT. THE H5 CIRCULATION REMAINS BROAD WITH CENTER TIGHTENING A
BIT OVERNIGHT WITH CENTER FORECAST OVER NC/VA BORDER BY SAT
MORNING. THE ASSOCIATED SURFACE LOW JUST E-SE OF CAPE FEAR THIS
AFTERNOON WILL MOVE NORTH AND BECOME MORE ELONGATED AS IT WEAKENS
THROUGH TONIGHT. NAM STILL SHOWING BEST ENERGY ASSOCIATED WITH
THIS LOW TO MOVE FROM COASTAL WATERS JUST SOUTH OF CAPE FEAR DUE
NORTH INTO NC THIS AFTERNOON. HRRR MODEL SHOWING BEST CHC FOR
HEAVIER PCP FROM THE TIP OF CAPE FEAR NORTH ALONG THE NORTH
CAROLINA COAST MAINLY FROM NEW HANOVER COUNTY THROUGH PENDER
COUNTY. THE BEST CHC OF HEAVIER PCP WILL OCCUR DURING THIS TIME
BUT BULLSEYE FOR HEAVIEST RAIN IN TSTMS WILL REMAIN OVER THE
WATERS TO THE EAST. THE GREATEST THREAT THROUGH WILL BE POTENTIAL
FOR FLOODING AS STEERING FLOW OVER MOST LAND AREAS WILL REMAIN
VERY WEAK. PCP WATER VALUES WILL REMAIN AROUND 2 INCHES UP THE
CAPE FEAR COAST DROPPING OFF AS YOU MOVE INLAND DOWN LESS THAN AN
INCH IN DRIER AIR AND SUBSIDENCE ON BACK END OF LOW WEST OF LOCAL
CWA...OVER CENTRAL TO WESTERN CAROLINAS. WILL KEEP LOW END POPS
INLAND AS SOME ENERGY ROTATES AROUND THE LOW...BUT OVERALL CLOUDS
AND COOLER NORTHERLY FLOW KEEPING TEMPS JUST AROUND 80 AND OVERALL
MORE STABLE ATMOSPHERE.
MODEL SOUNDINGS AND MOISTURE PROFILES SHOWING DRIER AIR WORKING
ITS WAY IN ON THE BACK EDGE OF LOW THROUGH THE MID TO UPPER
LEVELS TONIGHT AS IT LIFTS OFF TO THE NORTH. THIS WILL HELP PCP
SHUT OFF OVER LOCAL AREA. NAM SHOWS PCP WATER VALUES DROPPING
DOWN LESS THAN 1.5 INCHES BY SAT MORNING. CLOUDS...PCP AND FOG
WILL HELP KEEP TEMPS IN THE MID 60S AND CLOSER TO 70 WHERE GREATER
DEWPOINT AIR WILL HANG ON THE LATEST. MAY SEE STRATUS DEVELOP AS
MOISTURE BECOMES TRAPPED UNDER LOW LEVEL INVERSION...MORE PROBABLE
CLOSER TO THE COAST.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 340 PM FRIDAY...A DRIER PATTERN ANTICIPATED THIS WEEKEND...AS
DRY MID-LEVEL AIR OVERSPREADS THE REGION...AND A SURFACE LOW PULLS
SLUGGISHLY NORTH AND AWAY FROM OUR AREA. WEAK UPPER LOW POSITIONED
JUST NORTH OF OUR AREA SATURDAY AND SUNDAY WILL CONTINUE TO FEED
DRY AIR ALOFT...BUT CONCURRENTLY SHOULD PROMPT PLENTY OF DIURNAL
BUT MOSTLY CAPPED CUMULUS. CONVERGENCE OFFSHORE LATE IN THE PERIOD
MAY BRING COASTAL SHOWERS SUNDAY NIGHT. WHILE A SHOWER CANNOT BE
RULED OUT ON THE SEA BREEZE FRONT THIS WEEKEND...ACTIVITY SHOULD
IN OR BELOW THE ISOLATED CATEGORY.
MAXIMUM TEMPS WITH PARTIAL CLOUDS AND HIGH PRESSURE WEDGED IN FROM
THE NORTH...SHOULD RESULT IN MAINLY MIDDLE AND UPPER 80S BOTH DAYS.
MINIMUM TEMPS WILL DIP BELOW 70 MOST LOCATIONS BY DAYBREAK SAT/SUN
BUT QUITE A BIT MORE MILD AT THE COAST IN ONSHORE WIND DIRECTION.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 340 PM FRIDAY...SENSIBLE WEATHER THROUGH THE EXTENDED WILL
DEPEND ALMOST ENTIRELY ON ISAAC AND HIS POTENTIAL IMPACTS TO THE
REGION. STILL CONSIDERABLE UNCERTAINTY DUE TO TRACK
FORECASTS...WHICH...UNFORTUNATELY...WILL CREATE SIGNIFICANT
DIFFERENCES IN THE WEATHER ACROSS THE ILM CWA.
GFS/CMC ARE IN DECENT AGREEMENT WITH THEIR OVERALL EVOLUTION OF
ISAAC WHEN COMPARED TO THE ECMWF WHICH IS THE OUTLIER OF THE THREE
MODELS. WHILE THE ECMWF SLOWLY BRINGS ISAAC UP THROUGH THE GULF
COAST AND MEANDERS IT NW INTO THE TN VLY THROUGH MIDWEEK BEFORE
DISSIPATING...THE GFS/CMC BRING IT SLIGHTLY FURTHER EAST INTO THE
PANHANDLE OF FLORIDA ON TUESDAY AND THEN MAKE A SHARP
RECURVE...MOVING ISAAC`S REMNANTS BASICALLY OVER THE ILM CWA ON
WEDNESDAY. WILL LEAN TOWARDS THE GFS/CMC CONSENSUS...THE THINKING
THAT THE LARGE RIDGE WHICH FORCES THE ECMWF SOLUTION TO REMAIN WEST
IS OVERDONE. THIS MEANS DEEP S/SE FLOW MON/TUE WHICH SHOULD SUPPORT
ADVECTION SHOWERS...ESPECIALLY NEAR THE COAST...AND THEN A MUCH
WETTER DAY WEDNESDAY AS MID LEVEL THETA-E RIDGE ASSOCIATED WITH
ISAAC AND ITS REMNANTS...MOVES OVERHEAD. BY THURSDAY WE SHOULD BE ON
THE DRY WEST SUBSIDENT SIDE OF THE STORM AND WILL DRY OUT FOR LATE
WEEK. STILL MUCH UNCERTAINTY...BUT WILL RAMP POP UPWARDS THROUGH
WEDNESDAY BEFORE RAPIDLY TAILING OFF ON THURSDAY/FRIDAY.
NOTE THAT CURRENT FORECAST IS AT LEAST SLIGHTLY DIFFERENT THAN
HPC/NHC WHICH IS FAVORING A MUCH MORE WESTERN AND SLOWER
TRACK...ECMWF...FOR ISAAC. IF THE ECMWF TRACK WERE TO
VERIFY...WEDNESDAY WOULD STILL BE THE WETTEST DAY...SO POP TRENDS
WOULD STILL BE CORRECT...BUT OVERALL LESS RAINFALL ALONG WITH SLOWER
DECREASE IN POP WOULD BE NEEDED IN THAT SOLUTION (I.E. BETTER RAIN
CHANCES CONTINUING THROUGH THE END OF THE WEEK). WILL HAVE TO
MONITOR GUIDANCE TRENDS AND MODIFY FURTHER FORECAST UPDATES AS
NEEDED.
TEMPS WILL BE AROUND CLIMO MOST DAYS...WARMING TO ABOVE BY THE END
OF THE WEEK.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 06Z...A CLOSED MID-LEVEL LOW HAS MANIFESTED ITSELF ACROSS THE
ILM CWA THIS EARLY AM. DYNAMICS ASSOCIATED WITH THE LOW ALONG WITH
THE COLD POOL ALOFT...WILL BOTH COMBINE TO PRODUCE VCSH OR POSSIBLY
A SHORT PERIOD OF PREDOMINATE R- OR R DURING THE PRE-DAWN HRS ACROSS
MAINLY INLAND PORTIONS OF THE ILM CWA...EXTENDING FROM LBT TO
POSSIBLY FLO. WILL GO WITH THE MORE OPTIMISTIC FORECAST AND SAY THE
COLD POOL/CLOSED LOW LIFTS FAR ENOUGH NORTH OF THE AREA TODAY. THIS
WILL ALLOW DRIER AIR TO INFILTRATE THE ILM CWA...AS SEEN WITH THE
LATEST WATER VAPOR IMAGERY TRENDS. LOOK FOR VFR CONDITIONS BY
14Z-16Z...WHICH WILL CONTINUE FOR THE REMAINDER OF THE FORECAST
PERIOD. FOR THE COASTAL TERMINALS...A WEAK N TO NE SFC WIND AROUND 5
KT EARLY THIS AFTERNOON WILL VEER TO THE E-SE THIS AFTERNOON DUE TO
A WEAK RESULTANT WIND OR WEAK SEA BREEZE. ANY CLOUDINESS LEFT THIS
AFTERNOON WILL LIKELY DISSIPATE OR FADE AWAY LEAVING A MOSTLY CLEAR
SKY TO START THE OVERNITE PERIOD.
EXTENDED OUTLOOK...ISOLATED SHRA/TSRA MON. BETTER CHANCE OF SHOWERS
AND STORMS TUESDAY AND WEDNESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 10:30 PM FRIDAY...LATEST OBS SHOW WINDS ARE SETTLING INTO A
NORTHWESTERLY FLOW...WITH WINDS NOW IN THE 10 TO 15 KT
RANGE...HIGHEST NORTH. SEAS RANGE FROM 2 TO 4 FT. NO CHANGES TO
THE GOING FORECAST...PREVIOUS DISCUSSION FOLLOWS:
SFC WINDS OF AROUND 15 KTS WILL DIMINISH A BIT OVERNIGHT AS THEY
BACK TOWARD THE NW. THIS OFF-SHORE FLOW WILL ACT TO LOWER SEAS BUT
A LONGER PERIOD E-SE SWELL UP TO 16 SECONDS WILL COUNTERACT THIS
OFF SHORE FLOW AND WILL PRODUCE A SLIGHT INCREASE IN OVERALL SEAS
OVERNIGHT. SEAS WILL BUILD TO 3 TO 4 FT MAINLY ACROSS THE OUTER
WATERS. EXPECT ROUGHER SEAS WITH HIGHER WINDS AND SEAS IN TSTMS
THROUGH THIS EVENING AND ALSO REDUCED VSBYS DUE TO HEAVY RAIN.
RADAR CONTINUED TO SHOW THE POSSIBILITY OF WATERSPOUTS IN STORMS
OVER THE OUTER COASTAL WATERS THIS AFTERNOON.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 340 PM
FRIDAY...OUTSIDE OF TSTMS WINDS WILL REMAIN MANAGEABLE SATURDAY
AND SUNDAY...AS A SURFACE LOW OVER THE WATERS MOVES SLOWLY NORTH
OF THE AREA. WINDS WILL VEER EAST SUNDAY AS HIGH PRESSURE
CONSOLIDATES OVER NEW ENGLAND. THE COMBINATION OF WIND- WAVES AND
SWELL WAVES WILL KEEP SEAS MAINLY 3-4 FEET THIS WEEKEND AND UP TO
5 FEET AT TIMES WELL OFFSHORE. NUMEROUS SHOWERS AND TSTMS WILL
BECOME SCATTERED TO ISOLATED THIS WEEKEND...AS THE SFC LOW PULLS
NORTH OF SURF CITY BY DAYBREAK SATURDAY...AND DRY AIR ALOFT HELPS
TO SQUELCH STORM DEVELOPMENT.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 340 PM FRIDAY...QUITE A BIT OF UNCERTAINTY THROUGH THE
EXTENDED AS WIND/WAVE CONDITIONS COULD VARY CONSIDERABLY DEPENDING
ON WHAT HAPPENS WITH TS ISAAC. ANTICIPATE E/SE WINDS MON THROUGH TUE
AS ISAAC MOVES ALONG THE WEST COAST OF FLORIDA AND INTO THE GULF
COAST REGION. THE CONTINUED E/SE WINDS AROUND 10 KTS...UP TO 15 KTS
ACROSS THE SOUTHERN WATERS...WILL GENERATE 2-4 FT SOUTHERLY WIND
WAVES. THESE WIND WAVES WILL COMBINE WITH WHAT SHOULD BE INCREASING
S/SE SWELL OF 4-5FT/9SEC DUE TO TROPICAL SYSTEMS ISAAC AND JOYCE.
GUIDANCE IS NOT VERY ROBUST IN DEVELOPING ANY SIGNIFICANT VERY LONG
PERIOD SWELL...BUT NEVERTHELESS...3-5 FT SEAS ARE EXPECTED THROUGH
TUESDAY...WITH 6 FOOTERS POSSIBLE ACROSS THE SOUTHERN WATERS. SEAS
COULD BUILD MUCH HIGHER WEDNESDAY...ESPECIALLY IF GFS/CMC ARE
CORRECT...DUE TO INCREASING SOUTHERLY WINDS...AND SMALL CRAFT
ADVISORY CONDITIONS WILL BE POSSIBLE AT THE END OF THE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...REK/RGZ
SHORT TERM...MJC
LONG TERM...JDW
AVIATION...DCH/DL
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1155 PM CDT FRI AUG 24 2012
.UPDATE...REST OF TONIGHT
COLD FRONT CONTINUES TO MOVE EAST ACROSS THE REGION AND IS MOVING
THROUGH NORTH CENTRAL SD AT THIS TIME. MOST THUNDERSTORM ACTIVITY
HAS DIMINISHED AND 00Z NAM AND LATEST HRRR RUN INDICATE AREAL
COVERAGE THROUGH 12Z MAY BE LESS THAN ORIGINALLY FORECAST. HAVE
THEREFORE LOWERED POPS TO SLIGHT OR LOW CHANCE FOR THE REMAINDER
OF THE NIGHT.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
MAIN FORECAST CHALLENGE IS PRECIPITATION CHANCES TONIGHT THROUGH
SATURDAY MORNING. AS OF 19Z...A COLD FRONT WAS LOCATED OVER THE
FAR WESTERN DAKOTAS...AND WAS SLOWLY MAKING ITS WAY EASTWARD.
MODELS ARE IN GOOD AGREEMENT SHOWING THE FRONT HAVING JUST PUSHED
THROUGH THE FAR NORTHWESTERN CWA BY 06Z...THEN EXTENDING FROM
ABOUT KABR TO KPIR BY 12Z SATURDAY BEFORE PUSHING OFF TO THE EAST
OF THE CWA BY MIDDAY SATURDAY. THIS FRONT LOOKS TO BE THE FOCUS
FOR SHOWER AND THUNDERSTORM DEVELOPMENT THIS EVENING THROUGH
SATURDAY MORNING. HOWEVER...BEST UPPER LEVEL DYNAMICS WILL BE OVER
NORTH DAKOTA AS A SHORTWAVE TRACKS FROM NORTHERN MONTANA ACROSS
SOUTH CENTRAL CANADA. INSTABILITY WILL BE AT ITS BEST DURING THE
EVENING HOURS WITH CAPE VALUES OF 500-1000 J/KG AND LIS BETWEEN 0
AND -4. 0-6KM WIND SHEAR IS PRETTY WEAK OVER THE CWA THIS
EVENING...BUT DOES GET A BIT BETTER OVERNIGHT...HOWEVER THIS LOOKS
TO OCCUR POST FRONTAL. SHEAR VALUES WILL BE MUCH BETTER TO THE
NORTH. SO...THINKING THERE WILL BE SHOWERS AND THUNDERSTORMS
DURING THE EVENING AND OVERNIGHT HOURS...BUT AT THIS TIME IT LOOKS
LIKE BEST CHANCES OF SEVERE WILL BE NORTH OF THE CWA.
HOWEVER...CANNOT TOTALLY RULE OUT A STORM OR TWO BECOMING STRONG
ACROSS THE FAR NORTHERN CWA...BUT IT SHOULD BE LIMITED TO THAT
AREA. WILL LIKELY SEE SOME SHOWER ACTIVITY LINGER ACROSS THE EAST
INTO SATURDAY MORNING.
SURFACE HIGH PRESSURE SETTLES IN OVER THE REGION SATURDAY
AFTERNOON THROUGH THE DAY SUNDAY. A WARM FRONT ASSOCIATED WITH LOW
PRESSURE OVER THE NORTHERN AND CENTRAL ROCKIES WILL APPROACH THE
AREA SUNDAY NIGHT...AND MAY BRING A FEW SHOWERS OR THUNDERSTORMS
TO THE SOUTHERN CWA. WILL KEEP POPS IN THE SCHC CATEGORY FOR NOW.
COOLER AIR AND THE POTENTIAL OF MORE CLOUD COVER WITH THE POSSIBLE
PRECIPITATION WILL KEEP DAYTIME HIGHS ON SATURDAY NEAR TO SLIGHTLY
BELOW NORMAL. WILL SEE TEMPERATURES REBOUND ON SUNDAY AS WAA
REDEVELOPS WITH THE APPROACH OF THE WARM FRONT...BRINGING
AFTERNOON HIGHS BACK INTO THE MID 80S TO LOWER 90S.
.LONG TERM...MONDAY THROUGH FRIDAY
MEDIUM TO LONG RANGE MODELS CONTINUE TO ADVERTISE SIMILAR LONG
WAVE PATTERN NEXT WEEK. MID LVL RIDGE OF HIGH PRESSURE WILL BE
POISED OVER THE CENTRAL ROCKIES AND CENTRAL PLAINS WITH THE RIDGE
AXIS EXTENDING INTO THE NORTHERN HIGH PLAINS. GUIDANCE PROGS THIS
TO GRADUALLY BUILD AND SLIDE EWD ACROSS THE MID SECTION OF THE
COUNTRY TOWARD THE MIDDLE OF NEXT WEEK. AS THIS FEATURE BECOMES THE
MORE DOMINANT WEATHER MAKER EARLY IN THE PERIOD...CONDITIONS ARE
LIKELY TO REMAIN DRY. CAN`T RULE OUT SOME POP UP CONVECTION EARLY
IN THE PERIOD...IF A WEAK WAVE MOVES THRU...BUT CONFIDENCE IS TOO
LOW IN PCPN CHANCES AND PLACEMENT TO INCLUDE IN THE FORECAST.
LOCALLY...HEIGHT RISES DURING THE FIRST HALF OF THE WEEK WILL
TRANSLATE INTO RATHER HOT TEMPERATURES FOR LATE AUGUST. AN UPPER
TROUGH WILL CRASH INTO THE PACIFIC NORTHWEST TOWARD THE MIDDLE OF
THE WEEK AND THEN POTENTIALLY INTO OUR REGION BY THE END OF THE
PERIOD. HOWEVER...INCONSISTENCIES STILL EXIST WITH THIS FEATURE
AMONG THE LONG RANGE GUIDANCE SO HAVE KEPT THE FORECAST DRY AND
COOLED TEMPS JUST A BIT LATE IN THE PERIOD.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
A COLD FRONT WILL SWEEP ACROSS THE CWA OVERNIGHT. WINDS WILL SHIFT
TO THE NORTHWEST BEHIND THE FRONT. VFR CONDITIONS ARE EXPECTED
THROUGH SATURDAY.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...TMT
SHORT TERM...PARKIN
LONG TERM...VIPOND
AVIATION...WISE
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1055 AM EDT SAT AUG 25 2012
.SYNOPSIS...
HIGH PRESSURE CENTERED NEAR THE CANADIAN MARITIMES WILL TRACK
EASTWARD TODAY THEN BECOMES ELONGATED BACK TOWARDS THE NEW ENGLAND
COAST TONIGHT AND SUNDAY. MEANWHILE...AN UPPER LEVEL LOW OVER THE
MID ATLANTIC WILL MOVE SLOWLY NORTHEAST TOWARD THE AREA. A COLD
FRONT IS FORECAST TO MOVE SOUTHEAST CROSS THE AREA TUESDAY
FOLLOWED BY HIGH PRESSURE WEDNESDAY THROUGH FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MINOR UPDATES TO DEW POINT THIS MORNING. OTHERWISE...REMAINDER OF
FORECAST IS ON TRACK.
A WEAK UPPER LEVEL LOW PRESSURE SYSTEM OVER THE MID ATLANTIC
STATES WILL CONTINUE TO SEND ABUNDANT MID AND HIGH LEVEL CLOUDS
INTO THE AREA TODAY. SOME AREAS MAY EXPERIENCE FILTERED SUNSHINE
THIS MORNING BUT IT WILL EVENTUALLY GIVE WAY TO THICKER CLOUDS
WITH MOSTLY CLOUDY SKIES DEVELOPING BY AFTERNOON.
VORT ENERGY FROM THIS LOW WILL ADVANCE TOWARDS THE AREA TODAY. 12Z
SOUNDING SHOWING THAT AN ONSHORE FLOW HAS RESULTED IN A INCREASE
OF LOW LEVEL MOISTURE AND THERE COULD BE A FEW SHOWERS AROUND
LATER THIS AFTERNOON. LATEST HRRR DOES INDICATE SOME LIGHT ECHOES
EARLY THIS AFTERNOON ACROSS WESTERN PORTIONS OF THE CWA. HAVE
MAINTAINED SCHC POPS AS A RESULT. SUBSIDENCE FROM DEPARTING HIGH
PRES MAY BE ENOUGH TO KEEP EXTREME EASTERN AREAS DRY TODAY SO NO
POPS.
MOS GUIDANCE WAS CLOSE ON HIGH TEMPS TODAY AND USED A BLEND.
THERE IS A MODERATE RISK OF RIP CURRENTS AT ATLANTIC OCEAN BEACHES
TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
UPPER LEVEL RIDGING OVER THE ATLANTIC BUILDS BACK TOWARDS THE
EAST COAST TONIGHT WITH THE UPPER LEVEL LOW WEAKENING. HAVE GONE
WITH A DRY FORECAST UNTIL LATE TONIGHT THROUGH SUNDAY WITH ONLY SCHC
POPS RETURNING ACROSS WESTERN AREAS AS MAJORITY OF MOISTURE AND
LIFT ASSOCIATED WITH THE MID ATLANTIC SYSTEM ARE FORECAST TO REMAIN TO
OUR SW.
ONSHORE FLOW CONTINUES THROUGH SUN WITH TEMPERATURES NEAR NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
UPPER LEVEL LOW IN MID-ATLANTIC FINALLY GETS ABSORBED INTO MEAN
FLOW SUN NIGHT AND MOVES ACROSS MON MORNING. THIS WILL BE THE BEST
CHC OF THE LOCAL AREA SEEING ANY PRECIP FROM THIS SYSTEM. ELEVATED
INSTABILITY ALSO DEVELOPS SO TSTMS WILL BE POSSIBLE. FCST MODELS
SHOW A STRONGER UPPER LVL TROUGH APPROACHING WITH A HIGHER
PROBABILITY OF SCT SHOWERS AND TSTMS...MAINLY FROM MONDAY AFTN
THROUGH NOON TUESDAY. AS ALWAYS...TIMING THIS FRONTAL PASSAGE WILL
BE A CHALLENGE. AS THIS FRONT MOVES INTO A WARM...MOIST UNSTABLE
MARITIME TROPICAL AIR MASS...A FEW STORMS COULD PRODUCE HVY RAIN
AND STRONG GUSTY WINDS.
TUE NIGHT THROUGH FRI...FCST MODELS SHOW HIGH PRES MVG SE TOWARD
THE AREA COURTESY OF A WELL DEFINED HIGH AMPLITUDE UPSTREAM RIDGE
ACROSS THE WESTERN U.S. THIS WILL REPLACE THE MARITIME TROPICAL AIR
MASS WITH A FRESH AND DRIER CONTINENTAL POLAR AIR MASS.
REGARDING THE FORECAST FOR ISAAC...PLEASE REFER TO THE LATEST
NATIONAL HURRICANE CENTER FORECASTS. AT THIS TIME...IT APPEARS THAT
THE REMNANTS FROM ISAAC MAY PASS SOUTH OF THE LOCAL AREA NEXT
THURSDAY.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
HIGH PRESSURE WILL REMAIN NEAR THE CANADIAN MARITIMES THROUGH THE
DAY TODAY.
AN EAST TO SOUTHEAST FLOW ACROSS THE AREA WILL KEEP SOME STRATUS
AT THE COASTAL TERMINALS THROUGH MUCH OF THE DAY...HOWEVER...DO
NOT EXPECT MVFR CEILINGS.
VFR. WEAK LOW PRESSURE ALONG THE MID ATLANTIC COAST MAY BRING SOME
MID CLOUDS TO THE TERMINALS THIS AFTERNOON.
AN ISOLATED SHOWER THIS AFTERNOON WILL BE POSSIBLE...BUT DO NOT
EXPECT COVERAGE TO BE HIGH ENOUGH TO INCLUDE IN THE FORECAST AT
THIS TIME.
FOR TONIGHT...WINDS LIGHTEN AS THEY TURN BACK TOWARD THE
EAST/NORTHEAST. NOT TOO CONFIDENT IN FOG DEVELOPMENT TONIGHT...BUT
THIS WILL NEED TO BE WATCHED AS WELL.
OUTLOOK FOR 12Z SUNDAY THROUGH WED...
.SUNDAY...MAINLY VFR. ISOLATED SHOWERS/TSTMS POSSIBLE WITH BRIEF
MVFR OR LOWER CONDS.
.MON-TUE...MVFR OR LOWER CONDS POSSIBLE...ESPECIALLY IN ANY
SHOWERS/TSTMS THAT DEVELOP AS A COLD FRONT APPROACHES.
BEST CHANCES FOR THESE LOWER CONDITIONS TUE.
.WED...VFR.
&&
.MARINE...
AS HIGH PRESSURE MOVES AROUND THE CANADIAN MARITIMES AND OFF THE NEW
ENGLAND COAST THROUGH THE REMAINDER OF THE WEEKEND...EXPECT A
PERSISTENT EASTERLY WIND FLOW ACROSS THE LOCAL WATERS. THESE
EASTERLY WINDS WILL SHIFT AROUND THE SOUTH AND SOUTHWEST LATER MONDAY
AND MONDAY NIGHT. THIS WIND SHIFT WILL OCCUR AS THE CENTER OF THE
HIGH DRIFTS EAST AND A COLD FRONT APPROACHES FROM THE NORTHWEST.
THE COLD FRONT WILL PASS ACROSS THE WATERS TUESDAY...FOLLOWED BY
HIGH PRESSURE THROUGH MID WEEK.
SEAS SLOWLY BUILD THIS WEEKEND IN RESPONSE TO THE EASTERLY FLOW...BUT
DO EXPECT WINDS AND SEAS TO REMAIN JUST UNDER SCA CRITERIA.
SEAS SHOULD THEN SETTLE AND REMAIN AROUND 3 OR 4 FT THROUGH THE
EARLY PART OF THE WEEK ACROSS THE OCEAN WATERS.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH THE WEEKEND.
MON THROUGH TUE...SCT HEAVIER SHOWERS AND TSTMS COULD PRODUCE 1/2 TO
1 INCH OF RAIN IN ADVANCE OF AN APPROACHING COLD FRONT. ISOLATED
URBAN FLOODING IS POSSIBLE.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...BC
SHORT TERM...
LONG TERM...
AVIATION...MET
MARINE...
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1008 AM EDT SAT AUG 25 2012
.SYNOPSIS...
HIGH PRESSURE CENTERED NEAR THE CANADIAN MARITIMES WILL TRACK
EASTWARD TODAY THEN BECOMES ELONGATED BACK TOWARDS THE NEW ENGLAND
COAST TONIGHT AND SUNDAY. MEANWHILE...AN UPPER LEVEL LOW OVER THE
MID ATLANTIC WILL MOVE SLOWLY NORTHEAST TOWARD THE AREA. A COLD
FRONT IS FORECAST TO MOVE SOUTHEAST CROSS THE AREA TUESDAY
FOLLOWED BY HIGH PRESSURE WEDNESDAY THROUGH FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MINOR UPDATES TO DEW POINT THIS MORNING. OTHERWISE...REMAINDER OF
FORECAST IS ON TRACK.
A WEAK UPPER LEVEL LOW PRESSURE SYSTEM OVER THE MID ATLANTIC
STATES WILL CONTINUE TO SEND ABUNDANT MID AND HIGH LEVEL CLOUDS
INTO THE AREA TODAY. SOME AREAS MAY EXPERIENCE FILTERED SUNSHINE
THIS MORNING BUT IT WILL EVENTUALLY GIVE WAY TO THICKER CLOUDS
WITH MOSTLY CLOUDY SKIES DEVELOPING BY AFTERNOON.
VORT ENERGY FROM THIS LOW WILL ADVANCE TOWARDS THE AREA TODAY. 12Z
SOUNDING SHOWING THAT AN ONSHORE FLOW HAS RESULTED IN A INCREASE
OF LOW LEVEL MOISTURE AND THERE COULD BE A FEW SHOWERS AROUND
LATER THIS AFTERNOON. LATEST HRRR DOES INDICATE SOME LIGHT ECHOES
EARLY THIS AFTERNOON ACROSS WESTERN PORTIONS OF THE CWA. HAVE
MAINTAINED SCHC POPS AS A RESULT. SUBSIDENCE FROM DEPARTING HIGH
PRES MAY BE ENOUGH TO KEEP EXTREME EASTERN AREAS DRY TODAY SO NO
POPS.
MOS GUIDANCE WAS CLOSE ON HIGH TEMPS TODAY AND USED A BLEND.
THERE IS A MODERATE RISK OF RIP CURRENTS AT ATLANTIC OCEAN BEACHES
TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
UPPER LEVEL RIDGING OVER THE ATLANTIC BUILDS BACK TOWARDS THE
EAST COAST TONIGHT WITH THE UPPER LEVEL LOW WEAKENING. HAVE GONE
WITH A DRY FORECAST UNTIL LATE TONIGHT THROUGH SUNDAY WITH ONLY SCHC
POPS RETURNING ACROSS WESTERN AREAS AS MAJORITY OF MOISTURE AND
LIFT ASSOCIATED WITH THE MID ATLANTIC SYSTEM ARE FORECAST TO REMAIN TO
OUR SW.
ONSHORE FLOW CONTINUES THROUGH SUN WITH TEMPERATURES NEAR NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
UPPER LEVEL LOW IN MID-ATLANTIC FINALLY GETS ABSORBED INTO MEAN
FLOW SUN NIGHT AND MOVES ACROSS MON MORNING. THIS WILL BE THE BEST
CHC OF THE LOCAL AREA SEEING ANY PRECIP FROM THIS SYSTEM. ELEVATED
INSTABILITY ALSO DEVELOPS SO TSTMS WILL BE POSSIBLE. FCST MODELS
SHOW A STRONGER UPPER LVL TROUGH APPROACHING WITH A HIGHER
PROBABILITY OF SCT SHOWERS AND TSTMS...MAINLY FROM MONDAY AFTN
THROUGH NOON TUESDAY. AS ALWAYS...TIMING THIS FRONTAL PASSAGE WILL
BE A CHALLENGE. AS THIS FRONT MOVES INTO A WARM...MOIST UNSTABLE
MARITIME TROPICAL AIR MASS...A FEW STORMS COULD PRODUCE HVY RAIN
AND STRONG GUSTY WINDS.
TUE NIGHT THROUGH FRI...FCST MODELS SHOW HIGH PRES MVG SE TOWARD
THE AREA COURTESY OF A WELL DEFINED HIGH AMPLITUDE UPSTREAM RIDGE
ACROSS THE WESTERN U.S. THIS WILL REPLACE THE MARITIME TROPICAL AIR
MASS WITH A FRESH AND DRIER CONTINENTAL POLAR AIR MASS.
REGARDING THE FORECAST FOR ISAAC...PLEASE REFER TO THE LATEST
NATIONAL HURRICANE CENTER FORECASTS. AT THIS TIME...IT APPEARS THAT
THE REMNANTS FROM ISAAC MAY PASS SOUTH OF THE LOCAL AREA NEXT
THURSDAY.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
HIGH PRESSURE WILL REMAIN NEAR THE CANADIAN MARITIMES THROUGH THE
DAY TODAY.
AREAS OF MVFR OR IFR CONDITIONS IN FOG AND STRATUS EARLY THIS
MORNING WILL IMPROVE QUICKLY AS THE MORNING PROGRESSES.
THEREAFTER...VFR WITH MID AND HIGH CLOUDS EXPECTED TODAY. WINDS
REMAIN LIGHT E/NE EARLY THIS MORNING...THEN INCREASE FROM THE
EAST/SOUTHEAST CLOSE TO 10 KTS BY AFTERNOON. CANNOT RULE OUT AN
ISOLATED SHOWER THIS AFTERNOON...BUT DO NOT EXPECT COVERAGE TO BE
HIGH ENOUGH TO INCLUDE IN THE FORECAST AT THIS TIME. WILL NEED TO
MONITOR SHOWERS TO THE SOUTH.
FOR TONIGHT...WINDS LIGHTEN AS THEY TURN BACK TOWARD THE
EAST/NORTHEAST. NOT TOO CONFIDENT IN FOG DEVELOPMENT TONIGHT...BUT
THIS WILL NEED TO BE WATCHED AS WELL.
OUTLOOK FOR 12Z SUNDAY THROUGH WED...
.SUNDAY...MAINLY VFR. ISOLATED SHOWERS/TSTMS POSSIBLE WITH BRIEF
MVFR OR LOWER CONDS.
.MON-TUE...MVFR OR LOWER CONDS POSSIBLE...ESPECIALLY IN ANY
SHOWERS/TSTMS THAT DEVELOP AS A COLD FRONT APPROACHES.
BEST CHANCES FOR THESE LOWER CONDITIONS TUE.
.WED...VFR.
&&
.MARINE...
AS HIGH PRESSURE MOVES AROUND THE CANADIAN MARITIMES AND OFF THE NEW
ENGLAND COAST THROUGH THE REMAINDER OF THE WEEKEND...EXPECT A
PERSISTENT EASTERLY WIND FLOW ACROSS THE LOCAL WATERS. THESE
EASTERLY WINDS WILL SHIFT AROUND THE SOUTH AND SOUTHWEST LATER MONDAY
AND MONDAY NIGHT. THIS WIND SHIFT WILL OCCUR AS THE CENTER OF THE
HIGH DRIFTS EAST AND A COLD FRONT APPROACHES FROM THE NORTHWEST.
THE COLD FRONT WILL PASS ACROSS THE WATERS TUESDAY...FOLLOWED BY
HIGH PRESSURE THROUGH MID WEEK.
SEAS SLOWLY BUILD THIS WEEKEND IN RESPONSE TO THE EASTERLY FLOW...BUT
DO EXPECT WINDS AND SEAS TO REMAIN JUST UNDER SCA CRITERIA.
SEAS SHOULD THEN SETTLE AND REMAIN AROUND 3 OR 4 FT THROUGH THE
EARLY PART OF THE WEEK ACROSS THE OCEAN WATERS.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH THE WEEKEND.
MON THROUGH TUE...SCT HEAVIER SHOWERS AND TSTMS COULD PRODUCE 1/2 TO
1 INCH OF RAIN IN ADVANCE OF AN APPROACHING COLD FRONT. ISOLATED
URBAN FLOODING IS POSSIBLE.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...BC
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
730 AM EDT SAT AUG 25 2012
.SYNOPSIS...
HIGH PRESSURE CENTERED NEAR THE CANADIAN MARITIMES WILL TRACK
EASTWARD TODAY THEN BECOMES ELONGATED BACK TOWARDS THE NEW ENGLAND
COAST TONIGHT AND SUNDAY. MEANWHILE...AN UPPER LEVEL LOW OVER THE
MID ATLANTIC WILL MOVE SLOWLY NORTHEAST TOWARD THE AREA. A COLD
FRONT IS FORECAST TO MOVE SOUTHEAST CROSS THE AREA TUESDAY
FOLLOWED BY HIGH PRESSURE WEDNESDAY THROUGH FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MINOR UPDATES TO T/TD/SKY AND WINDS THIS MORNING. REMAINDER OF
FORECAST IS ON TRACK.
A WEAK UPPER LEVEL LOW PRESSURE SYSTEM OVER THE MID ATLANTIC
STATES WILL CONTINUE TO SEND ABUNDANT MID AND HIGH LEVEL CLOUDS
INTO THE AREA TODAY. SOME AREAS MAY EXPERIENCE FILTERED SUNSHINE
THIS MORNING BUT IT WILL EVENTUALLY GIVE WAY TO THICKER CLOUDS
WITH MOSTLY CLOUDY SKIES DEVELOPING BY AFTERNOON.
VORT ENERGY FROM THIS LOW WILL ADVANCE TOWARDS THE AREA TODAY. 00Z
OKX SOUNDING INDICATES A DRY PROFILE HOWEVER...AN ONSHORE FLOW
WILL BE INCREASING LOW LEVEL MOISTURE AND THERE COULD BE A FEW
SHOWERS AROUND. LATEST HRRR DOES INDICATE SOME LIGHT ECHOES EARLY
THIS AFTERNOON ACROSS WESTERN PORTIONS OF THE CWA. HAVE MAINTAINED
SCHC POPS AS A RESULT. HAVE REMOVED MENTION OF THUNDER WITH LITTLE
INSTABILITY FORECAST AND EQL LEVEL FORECAST TO BE AROUND -10C.
SUBSIDENCE FROM DEPARTING HIGH PRES MAY BE ENOUGH TO KEEP EXTREME
EASTERN AREAS DRY TODAY SO NO POPS.
MOS GUIDANCE WAS CLOSE ON HIGH TEMPS TODAY AND USED A BLEND.
THERE IS A MODERATE RISK OF RIP CURRENTS AT ATLANTIC OCEAN BEACHES
TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
UPPER LEVEL RIDGING OVER THE ATLANTIC BUILDS BACK TOWARDS THE
EAST COAST TONIGHT WITH THE UPPER LEVEL LOW WEAKENING. HAVE GONE
WITH A DRY FORECAST UNTIL LATE TONIGHT THROUGH SUNDAY WITH ONLY SCHC
POPS RETURNING ACROSS WESTERN AREAS AS MAJORITY OF MOISTURE AND
LIFT ASSOCIATED WITH THE MID ATLANTIC SYSTEM ARE FORECAST TO REMAIN TO
OUR SW.
ONSHORE FLOW CONTINUES THROUGH SUN WITH TEMPERATURES NEAR NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
UPPER LEVEL LOW IN MID-ATLANTIC FINALLY GETS ABSORBED INTO MEAN
FLOW SUN NIGHT AND MOVES ACROSS MON MORNING. THIS WILL BE THE BEST
CHC OF THE LOCAL AREA SEEING ANY PRECIP FROM THIS SYSTEM. ELEVATED
INSTABILITY ALSO DEVELOPS SO TSTMS WILL BE POSSIBLE. FCST MODELS
SHOW A STRONGER UPPER LVL TROUGH APPROACHING WITH A HIGHER
PROBABILITY OF SCT SHOWERS AND TSTMS...MAINLY FROM MONDAY AFTN
THROUGH NOON TUESDAY. AS ALWAYS...TIMING THIS FRONTAL PASSAGE WILL
BE A CHALLENGE. AS THIS FRONT MOVES INTO A WARM...MOIST UNSTABLE
MARITIME TROPICAL AIR MASS...A FEW STORMS COULD PRODUCE HVY RAIN
AND STRONG GUSTY WINDS.
TUE NIGHT THROUGH FRI...FCST MODELS SHOW HIGH PRES MVG SE TOWARD
THE AREA COURTESY OF A WELL DEFINED HIGH AMPLITUDE UPSTREAM RIDGE
ACROSS THE WESTERN U.S. THIS WILL REPLACE THE MARITIME TROPICAL AIR
MASS WITH A FRESH AND DRIER CONTINENTAL POLAR AIR MASS.
REGARDING THE FORECAST FOR ISAAC...PLEASE REFER TO THE LATEST
NATIONAL HURRICANE CENTER FORECASTS. AT THIS TIME...IT APPEARS THAT
THE REMNANTS FROM ISAAC MAY PASS SOUTH OF THE LOCAL AREA NEXT
THURSDAY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
HIGH PRESSURE WILL REMAIN NEAR THE CANADIAN MARITIMES THROUGH THE
DAY TODAY.
AREAS OF MVFR OR IFR CONDITIONS IN FOG AND STRATUS EARLY THIS
MORNING WILL IMPROVE QUICKLY AS THE MORNING PROGRESSES.
THEREAFTER...VFR WITH MID AND HIGH CLOUDS EXPECTED TODAY. WINDS
REMAIN LIGHT E/NE EARLY THIS MORNING...THEN INCREASE FROM THE
EAST/SOUTHEAST CLOSE TO 10 KTS BY AFTERNOON. CANNOT RULE OUT AN
ISOLATED SHOWER THIS AFTERNOON...BUT DO NOT EXPECT COVERAGE TO BE
HIGH ENOUGH TO INCLUDE IN THE FORECAST AT THIS TIME. WILL NEED TO
MONITOR SHOWERS TO THE SOUTH.
FOR TONIGHT...WINDS LIGHTEN AS THEY TURN BACK TOWARD THE
EAST/NORTHEAST. NOT TOO CONFIDENT IN FOG DEVELOPMENT TONIGHT...BUT
THIS WILL NEED TO BE WATCHED AS WELL.
OUTLOOK FOR 12Z SUNDAY THROUGH WED...
.SUNDAY...MAINLY VFR. ISOLATED SHOWERS/TSTMS POSSIBLE WITH BRIEF
MVFR OR LOWER CONDS.
.MON-TUE...MVFR OR LOWER CONDS POSSIBLE...ESPECIALLY IN ANY
SHOWERS/TSTMS THAT DEVELOP AS A COLD FRONT APPROACHES.
BEST CHANCES FOR THESE LOWER CONDITIONS TUE.
.WED...VFR.
&&
.MARINE...
AS HIGH PRESSURE MOVES AROUND THE CANADIAN MARITIMES AND OFF THE NEW
ENGLAND COAST THROUGH THE REMAINDER OF THE WEEKEND...EXPECT A
PERSISTENT EASTERLY WIND FLOW ACROSS THE LOCAL WATERS. THESE
EASTERLY WINDS WILL SHIFT AROUND THE SOUTH AND SOUTHWEST LATER MONDAY
AND MONDAY NIGHT. THIS WIND SHIFT WILL OCCUR AS THE CENTER OF THE
HIGH DRIFTS EAST AND A COLD FRONT APPROACHES FROM THE NORTHWEST.
THE COLD FRONT WILL PASS ACROSS THE WATERS TUESDAY...FOLLOWED BY
HIGH PRESSURE THROUGH MID WEEK.
SEAS SLOWLY BUILD THIS WEEKEND IN RESPONSE TO THE EASTERLY FLOW...BUT
DO EXPECT WINDS AND SEAS TO REMAIN JUST UNDER SCA CRITERIA.
SEAS SHOULD THEN SETTLE AND REMAIN AROUND 3 OR 4 FT THROUGH THE
EARLY PART OF THE WEEK ACROSS THE OCEAN WATERS.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH THE WEEKEND.
MON THROUGH TUE...SCT HEAVIER SHOWERS AND TSTMS COULD PRODUCE 1/2 TO
1 INCH OF RAIN IN ADVANCE OF AN APPROACHING COLD FRONT. ISOLATED
URBAN FLOODING IS POSSIBLE.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
643 AM EDT SAT AUG 25 2012
.SYNOPSIS...
HIGH PRESSURE CENTERED NEAR THE CANADIAN MARITIMES WILL TRACK
EASTWARD TODAY THEN BECOMES ELONGATED BACK TOWARDS THE NEW ENGLAND
COAST TONIGHT AND SUNDAY. MEANWHILE...AN UPPER LEVEL LOW OVER THE
MID ATLANTIC WILL MOVE SLOWLY NORTHEAST TOWARD THE AREA. A COLD
FRONT IS FORECAST TO MOVE SOUTHEAST CROSS THE AREA TUESDAY
FOLLOWED BY HIGH PRESSURE WEDNESDAY THROUGH FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MINOR UPDATES TO T/TD/SKY AND WINDS THIS MORNING. REMAINDER OF
FORECAST IS ON TRACK.
A WEAK UPPER LEVEL LOW PRESSURE SYSTEM OVER THE MID ATLANTIC
STATES WILL CONTINUE TO SEND ABUNDANT MID AND HIGH LEVEL CLOUDS
INTO THE AREA TODAY. SOME AREAS MAY EXPERIENCE FILTERED SUNSHINE
THIS MORNING BUT IT WILL EVENTUALLY GIVE WAY TO THICKER CLOUDS
WITH MOSTLY CLOUDY SKIES DEVELOPING BY AFTERNOON.
VORT ENERGY FROM THIS LOW WILL ADVANCE TOWARDS THE AREA TODAY. 00Z
OKX SOUNDING INDICATES A DRY PROFILE HOWEVER...AN ONSHORE FLOW
WILL BE INCREASING LOW LEVEL MOISTURE AND THERE COULD BE A FEW
SHOWERS AROUND. LATEST HRRR DOES INDICATE SOME LIGHT ECHOES EARLY
THIS AFTERNOON ACROSS WESTERN PORTIONS OF THE CWA. HAVE MAINTAINED
SCHC POPS AS A RESULT. HAVE REMOVED MENTION OF THUNDER WITH LITTLE
INSTABILITY FORECAST AND EQL LEVEL FORECAST TO BE AROUND -10C.
SUBSIDENCE FROM DEPARTING HIGH PRES MAY BE ENOUGH TO KEEP EXTREME
EASTERN AREAS DRY TODAY SO NO POPS.
MOS GUIDANCE WAS CLOSE ON HIGH TEMPS TODAY AND USED A BLEND.
THERE IS A MODERATE RISK OF RIP CURRENTS AT ATLANTIC OCEAN BEACHES
TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
UPPER LEVEL RIDGING OVER THE ATLANTIC BUILDS BACK TOWARDS THE
EAST COAST TONIGHT WITH THE UPPER LEVEL LOW WEAKENING. HAVE GONE
WITH A DRY FORECAST UNTIL LATE TONIGHT THROUGH SUNDAY WITH ONLY SCHC
POPS RETURNING ACROSS WESTERN AREAS AS MAJORITY OF MOISTURE AND
LIFT ASSOCIATED WITH THE MID ATLANTIC SYSTEM ARE FORECAST TO REMAIN TO
OUR SW.
ONSHORE FLOW CONTINUES THROUGH SUN WITH TEMPERATURES NEAR NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
UPPER LEVEL LOW IN MID-ATLANTIC FINALLY GETS ABSORBED INTO MEAN
FLOW SUN NIGHT AND MOVES ACROSS MON MORNING. THIS WILL BE THE BEST
CHC OF THE LOCAL AREA SEEING ANY PRECIP FROM THIS SYSTEM. ELEVATED
INSTABILITY ALSO DEVELOPS SO TSTMS WILL BE POSSIBLE. FCST MODELS
SHOW A STRONGER UPPER LVL TROUGH APPROACHING WITH A HIGHER
PROBABILITY OF SCT SHOWERS AND TSTMS...MAINLY FROM MONDAY AFTN
THROUGH NOON TUESDAY. AS ALWAYS...TIMING THIS FRONTAL PASSAGE WILL
BE A CHALLENGE. AS THIS FRONT MOVES INTO A WARM...MOIST UNSTABLE
MARITIME TROPICAL AIR MASS...A FEW STORMS COULD PRODUCE HVY RAIN
AND STRONG GUSTY WINDS.
TUE NIGHT THROUGH FRI...FCST MODELS SHOW HIGH PRES MVG SE TOWARD
THE AREA COURTESY OF A WELL DEFINED HIGH AMPLITUDE UPSTREAM RIDGE
ACROSS THE WESTERN U.S. THIS WILL REPLACE THE MARITIME TROPICAL AIR
MASS WITH A FRESH AND DRIER CONTINENTAL POLAR AIR MASS.
REGARDING THE FORECAST FOR ISAAC...PLEASE REFER TO THE LATEST
NATIONAL HURRICANE CENTER FORECASTS. AT THIS TIME...IT APPEARS THAT
THE REMNANTS FROM ISAAC MAY PASS SOUTH OF THE LOCAL AREA NEXT
THURSDAY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
HIGH PRESSURE WILL REMAIN NEAR THE CANADIAN MARITIMES THROUGH THE
DAY TODAY.
EXPECT AREAS OF MVFR OR IFR CONDITIONS IN FOG EARLY THIS
MORNING...MAINLY OUTSIDE OF NYC METRO TERMINALS. OTHERWISE...VFR
WITH MID AND HIGH CLOUDS TODAY. WINDS REMAIN LIGHT EARLY THIS
MORNING...THEN INCREASE FROM THE EAST/SOUTHEAST CLOSE TO 10 KTS BY
AFTERNOON. CANNOT RULE OUT AN ISOLATED SHOWER THIS AFTERNOON...BUT
DO NOT EXPECT COVERAGE TO BE HIGH ENOUGH TO INCLUDE IN THE
FORECAST AT THIS TIME.
OUTLOOK FOR 06Z SUNDAY THROUGH WED...
.SUNDAY...MAINLY VFR. ISOLATED SHOWERS/TSTMS POSSIBLE WITH BRIEF
MVFR OR LOWER CONDS.
.MON-TUE...MVFR OR LOWER CONDS POSSIBLE...ESPECIALLY IN ANY
SHOWERS/TSTMS THAT DEVELOP AS A COLD FRONT APPROACHES.
BEST CHANCES FOR THESE LOWER CONDITIONS TUE INTO TUE NIGHT.
.WED...VFR.
&&
.MARINE...
AS HIGH PRESSURE MOVES AROUND THE CANADIAN MARITIMES AND OFF THE NEW
ENGLAND COAST THROUGH THE REMAINDER OF THE WEEKEND...EXPECT A
PERSISTENT EASTERLY WIND FLOW ACROSS THE LOCAL WATERS. THESE
EASTERLY WINDS WILL SHIFT AROUND THE SOUTH AND SOUTHWEST LATER MONDAY
AND MONDAY NIGHT. THIS WIND SHIFT WILL OCCUR AS THE CENTER OF THE
HIGH DRIFTS EAST AND A COLD FRONT APPROACHES FROM THE NORTHWEST.
THE COLD FRONT WILL PASS ACROSS THE WATERS TUESDAY...FOLLOWED BY
HIGH PRESSURE THROUGH MID WEEK.
SEAS SLOWLY BUILD THIS WEEKEND IN RESPONSE TO THE EASTERLY FLOW...BUT
DO EXPECT WINDS AND SEAS TO REMAIN JUST UNDER SCA CRITERIA.
SEAS SHOULD THEN SETTLE AND REMAIN AROUND 3 OR 4 FT THROUGH THE
EARLY PART OF THE WEEK ACROSS THE OCEAN WATERS.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH THE WEEKEND.
MON THROUGH TUE...SCT HEAVIER SHOWERS AND TSTMS COULD PRODUCE 1/2 TO
1 INCH OF RAIN IN ADVANCE OF AN APPROACHING COLD FRONT. ISOLATED
URBAN FLOODING IS POSSIBLE.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
935 AM EDT SAT AUG 25 2012
.UPDATE (REST OF TODAY)...
13Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS OUR REGION LOCATED UNDER A
MID/UPPER LEVEL WEAKNESS IN THE HEIGHT FIELD BETWEEN RIDGING OVER
THE CENTRAL/WESTERN GULF OF MEXICO...AND ANOTHER RIDGE OFF THE SE
CONUS. SEEING A WEAK DISTURBANCE NEAR THE FLORIDA STRAITS THAT IS
SUPPORTING A BROAD AREA OF RAIN/THUNDER OVER THE SE/S FL PENINSULA
THIS MORNING. GUIDANCE IS HAVING A DIFFICULT TIME WITH THIS
FEATURE...AND WILL CONTINUE TO MAKE FORECAST ADJUSTMENTS TO THE RAIN
CHANCES DOWN TOWARD CHARLOTTE AND LEE COUNTIES INTO THE AFTERNOON
HOURS. MOST OF THE RAINFALL SHOULD REMAIN EAST AND SOUTH OF OF
LEE/CHARLOTTE COUNTIES AS SPEED CONVERGENCE FOCUS WEAKENS INLAND
FROM THE EAST COAST. ANY SHOWERS/STORMS THAT DO OCCUR ARE NOT
ASSOCIATED WITH ANY OUTER-BANDS OF ISAAC. THIS IS A SEPARATE
MID-LEVEL FEATURE WHICH WILL BE PASSING OUT IN THE SE GULF LATER
TODAY/TONIGHT.
AT THE SURFACE...FORECAST AREA RESIDES BETWEEN A 1022MB RIDGE CENTER
OVER THE CAROLINAS...AND THE LOW PRESSURE ASSOCIATED WITH TS ISAAC
DOWN TOWARD THE EASTERN TIP OF CUBA. THE LOCAL GRADIENT IS
TIGHTENING BETWEEN THESE 2 FEATURES WHICH WILL ALLOW FOR SOME GUSTY
WINDS OUT OF THE EAST THIS AFTERNOON. ANALYSIS SHOWS A MORE
MESOSCALE...BUT SHARP INVERTED TROUGH ALONG THE FLORIDA EAST COAST
WHICH IS ALSO HELPING TO FOCUS THE LIFT FOR SHOWERS/STORMS TO OUR
EAST AND SOUTH.
CURRENT THINKING IS THAT RAIN CHANCES WILL FALL (EVEN FOR THE FAR
SOUTH) LATER TODAY INTO THE OVERNIGHT HOURS AS THE DISTURBANCE
MENTIONED ABOVE EXITS THE REGION. WE WILL THEN BEGIN TO AWAIT THE
ARRIVAL OF RAINBANDS FROM THE SOUTHEAST ASSOCIATED WITH ISAAC. GOOD
MODEL AGREEMENT THAT THESE FIRST OUTER-BANDS WILL ARRIVE DOWN TOWARD
LEE/CHARLOTTE COUNTIES DURING THE DAYLIGHT HOURS OF SUNDAY.
&&
.SHORT TERM (TODAY-MONDAY)...
LEANING TOWARD SLIGHTLY HIGHER POPS OVERNIGHT OVER THE SOUTHERN HALF
OF THE FORECAST AREA WITH BEST CHANCE OF A SHOWER IN THE FORT MYERS
AREA. BIG QUESTIONS ARISE SUNDAY INTO MONDAY ON EVENTUAL TRACK AND
STRENGTH OF ISAAC AS IT MOVES THROUGH THE FLORIDA STRAITS AND OVER
THE EASTERN GULF OF MEXICO. GIVEN LATEST NHC TRACK AND INTENSITY
FORECAST...EXPECT NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS TO
SPREAD OVER SOUTHWEST FLORIDA AND SOUTHERN INTERIOR SUNDAY
MORNING...AND AS FAR NORTH AS THE I-4 CORRIDOR SUNDAY AFTERNOON WITH
WIDESPREAD HEAVY SHOWERS DEVELOPING OVER SOUTHWEST FLORIDA. PERIODS
OF HEAVY RAIN AND STRONG GUSTY WINDS SUNDAY NIGHT INTO MONDAY AS
ISAAC MOVES OVER THE EASTERN GULF. STILL TOO EARLY FOR SPECIFICS AS
EVENTUAL TRACK AND INTENSITY REMAIN UNCERTAIN...BUT GOOD CHANCE AS
ISAAC MOVES INTO THE EASTERN GULF THAT BAND OF HEAVY RAIN WILL
DEVELOP OVER WEST CENTRAL AND SOUTHWEST FLORIDA WITH HIGHEST
RAINFALL TOTALS NEAR THE COAST. A FLOOD WATCH MAY BE NEEDED ON
SUNDAY AND MONDAY. POTENTIAL FOR 5 TO 10 INCHES OF RAIN WITH LOCALLY
HIGHER AMOUNTS IF TRAINING DEVELOPS WITH SPIRAL BANDS EAST OF THE
CENTER. WILL RUN BELOW MOS GUIDANCE WITH TEMPERATURES SUNDAY AND
MONDAY FOR MOST AREAS AS INCREASING CLOUD COVER AND AREAS OF RAIN
SHOULD KEEP TEMPS COOLER.
&&
.AVIATION...
WINDS WILL BECOME GUSTY FROM THE NORTHEAST OR EAST. AREA OF SHOWERS
MOVING ACROSS SOUTH FLORIDA COULD IMPACT FMY...RSW AND PGD TODAY.
MOST TERMINALS STAY VFR WITH JUST A FEW VCTS IN THE AFTERNOON.
&&
.MARINE...
INCREASING WINDS AND SEAS TODAY AND SUNDAY AS THE GRADIENT
TIGHTENS OVER THE WATERS AHEAD OF ISAAC. SIGNIFICANT INCREASE IN
WAVES AND SEAS SUNDAY NIGHT AND MONDAY AS ISAAC MOVES OVER THE
EASTERN GULF WATERS. SEAS MAY NEED TO BE ADJUSTED HIGHER IF ISAAC
STRENGTHENS MORE THAN CURRENTLY FORECAST. WINDS AND SEAS WILL
GRADUALLY SUBSIDE TUESDAY AND WEDNESDAY FROM SOUTH TO NORTH AS ISAAC
PULLS AWAY FROM THE AREA.
&&
.HYDROLOGY...
FLOOD WARNINGS CONTINUE ON THE LITTLE MANATEE RIVER AND CYPRESS
CREEK. THE GROUND REMAINS SATURATED FROM RECENT HEAVY RAINS...AND
ADDITIONAL HEAVY RAIN EXPECTED FROM T.S. ISAAC MAY CAUSE
SIGNIFICANT FLOODING OF RIVERS OVER WEST CENTRAL FLORIDA MONDAY
INTO THE MIDDLE OF NEXT WEEK. FLOODING OF LOW LYING AND FLOOD
PRONE AREAS...WITH SIGNIFICANT FLOODING OF STREETS IN URBAN AREAS
IS POSSIBLE. THE GREATEST THREAT WILL BE SUNDAY NIGHT THROUGH
MONDAY NIGHT...BUT COULD EXTEND INTO TUESDAY OVER THE NORTHERN
HALF OF THE AREA DEPENDING ON THE EVENTUAL TRACK OF ISAAC.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 93 78 89 78 / 30 20 60 60
FMY 92 77 86 77 / 60 40 80 80
GIF 92 76 88 76 / 30 20 60 60
SRQ 93 78 89 78 / 50 20 60 80
BKV 93 73 91 74 / 30 20 40 60
SPG 90 80 89 80 / 30 20 60 80
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE...MROCZKA
PREVIOUS DISCUSSION/HYDROLOGY...OGLESBY
AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS GRAY ME
1137 AM EDT SAT AUG 25 2012
.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER NORTHERN NEW ENGLAND AND THEN SHIFT
OFFSHORE THIS WEEKEND. GENERALLY DRY AND SEASONABLY WARM
CONDITIONS ARE EXPECTED THROUGH EARLY NEXT WEEK BEFORE A COLD
FRONT MOVES THROUGH LATE TUESDAY OR EARLY WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1535Z...FOG AND LOW CLOUDS LOOK TO HAVE BROKEN UP IN MOST PLACES
ATTM...AND HAVE LEFT A BKN...BUT TRANSPARENT CI DECK IN THE SRN
HALF OF THE CWA. THIS SHOULD BE THE MAIN FEATURE FOR THE AFTERNOON
IN THE SOUTH. IN THE NORTH...STARTING TO SEE CU DEVELOP ON THE
TERRAIN...AS SOME INSTABILITY IS GENERATED. THIS TREND WILL
CONTINUE THRU THIS AFTERNOON...AND COMBINED WITH REMNANTS OF SFC
FRONTAL THATS BEEN SITTING OVER THE AREA ALL WEEK...EXPECT TO SEE
A FEW ISOLATED SHRA/TSRA DEVELOP THIS AFTERNOON.
MADE SOME MCHANGES...BASED ON CURRENT CONDS...TO
T/TD/SKY/POP...AND HAVE SENT OUT A FRESH SUITE OF TEXT PRODUCTS
FOR THIS AFTERNOON.
PREV DISC...
A COUPLE CHALLENGES TO THE FCST ONCE AGAIN THIS MORNING.
AFTER MORNING FOG MIXES OUT...HIGH CLOUDS WITH A FEW EMBEDDED AC
WILL CONTINUE TO RIDE INTO THE RIDGE POSITIONED OVER NEW ENGLAND
AND OFF THE EASTERN SEABOARD. THIS MAY LIMIT TEMPS OVER SOUTHERN
ME/NH BY A FEW DEGS DURING THE AFTN HOURS. OTHERWISE...PARTLY TO
MOSTLY SUNNY CONDITIONS WILL PREVAIL NORTH OF THIS REGION THIS
MORNING.
DURING THE AFTN...SUFFICIENT ENOUGH INSTABILITY WILL ALLOW FOR A
SMALL CHANCE FOR A BRIEF SHOWER OVER WRN NH AND THE WRN MTNS OF
MAINE IN THE PROXIMITY AROUND THE PERIPHERY OF THE SURFACE RIDGE.
WITH LI VALUES DROPPING IN THIS AREA AND AMPLE SFC HEATING...THERE
IS ALSO A RISK OF A TSTM IN THIS REGION. LATEST HRRR MODEL CONTS
TO PICK UP ON THIS WIDELY SCT AFTN PCPN.
USED A BLEND OF MAV/MET MOS FOR AFTN MAX TEMPS. AFTN SEA BREEZES
WILL KEEP THE COASTLINE COOLER ONCE AGAIN.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
MORE PATCHY FOG WILL DEVELOP TONIGHT...DESPITE MORE HIGH THIN
CLOUDINESS CROSSING OVER SRN ME/NH. ONCE AGAIN...SOME MID AND
UPPER 40S PSBL FOR OVERNIGHT LOWS IN THE MTNS.
A REPEAT PERFORMANCE OCCURS ON SUNDAY. STILL THE POSSIBILITY
EXISTS FOR A BRIEF SHOWER OR TSTM OVER NH AND THE WRN MTNS OF ME.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
THE LARGE BROAD SURFACE AND UPPER RIDGE WILL MOVE OFF THE COAST
AND ALLOW A RETURN SSWLY FLOW EARLY NEXT WEEK. TEMPS WILL BE MILD
AND DEWPOINTS WILL BE ON THE RISE EARLY NEXT WEEK WITH CONDITIONS
POSSIBLY BECOMING RATHER MUGGY. BY LATE MON AND TUE THE UPPER
RIDGE BREAKS DOWN ALLOWING AN UPPER TROF TO APPROACH THE AREA FROM
THE WEST SETTING OFF SHWRS/TSTMS LATE MON AND MON NIGHT WITH SCT
SHWRS TUES. A SFC CDFNT ASSOC WITH THE UPPER TROF WILL MOVE THRU
BY LATE TUES OR EARLY WED BRINGING WITH IT A MUCH DRIER CANADIAN
AMS AND COOLER TEMPS FOR THE MID TO LATTER PART OF THE WEEK.
&&
.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM...VFR CONDITIONS WILL PREVAIL ACROSS THE REGION
THROUGHOUT THE PERIOD. SOME VALLEY FOG MAY DEVELOP TONIGHT OVER
FAVORED LOCATIONS RESULTING IN A FEW HOURS OF IFR/LIFR CONDITIONS
BEFORE BURNING OFF EARLY TOMORROW MORNING.
LONG TERM...GENERALLY VFR EXCEPT SHOWERS AND THUNDERSTORMS
POSSIBLE MONDAY AFTERNOON AND MONDAY NIGHT ALLOWING MVFR CONDS TO
DEVELOP...THEN A CHC OF SHWRS TUESDAY.
&&
.MARINE...
SHORT TERM...NO FLAGS EXPECTED
LONG TERM...GENERALLY LIGHT FLOW OVER THE WATERS CONTINUES. COLD
FRONT MOVES THROUGH TUESDAY.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...CEMPA
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
AREA FORECAST DISCUSSION
NWS GRAY ME
915 AM EDT SAT AUG 25 2012
.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER NORTHERN NEW ENGLAND AND THEN SHIFT
OFFSHORE THIS WEEKEND. GENERALLY DRY AND SEASONABLY WARM
CONDITIONS ARE EXPECTED THROUGH EARLY NEXT WEEK BEFORE A COLD
FRONT MOVES THROUGH LATE TUESDAY OR EARLY WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1310Z...DENSE FOG ADV HAS EXPIRED...AND WHILE PATCHY FOG WILL
LINGER THRU MID-MORNING IN SOME SPOTS...VISBYS HAVE COME UP IN
MANY SPOTS. STILL...GIVEN A LACK OF FLOW IN THE LOWEST FEW
THOUSAND FEET...FOG COULD LINGER INTO LATE MORNING THE SHELTERED
SPOTS.
HAVE ALSO REWORKED POPS A BIT FOR THIS AFTERNOON...MAINLY TO SCALE
THEM BACK A BIT...AS THEY LOOK TO BE FORCED...MOSTLY...BY
TERRAIN. THEREFORE WENT WITH COVERAGE TERMINIOLOGY...AND SCALED
BACK TO MORE ISOLATED CONVECTIVE SHRA IN MANY SPOTS.
PREV DISC...
A COUPLE CHALLENGES TO THE FCST ONCE AGAIN THIS MORNING.
AFTER MORNING FOG MIXES OUT...HIGH CLOUDS WITH A FEW EMBEDDED AC
WILL CONTINUE TO RIDE INTO THE RIDGE POSITIONED OVER NEW ENGLAND
AND OFF THE EASTERN SEABOARD. THIS MAY LIMIT TEMPS OVER SOUTHERN
ME/NH BY A FEW DEGS DURING THE AFTN HOURS. OTHERWISE...PARTLY TO
MOSTLY SUNNY CONDITIONS WILL PREVAIL NORTH OF THIS REGION THIS
MORNING.
DURING THE AFTN...SUFFICIENT ENOUGH INSTABILITY WILL ALLOW FOR A
SMALL CHANCE FOR A BRIEF SHOWER OVER WRN NH AND THE WRN MTNS OF
MAINE IN THE PROXIMITY AROUND THE PERIPHERY OF THE SURFACE RIDGE.
WITH LI VALUES DROPPING IN THIS AREA AND AMPLE SFC HEATING...THERE
IS ALSO A RISK OF A TSTM IN THIS REGION. LATEST HRRR MODEL CONTS
TO PICK UP ON THIS WIDELY SCT AFTN PCPN.
USED A BLEND OF MAV/MET MOS FOR AFTN MAX TEMPS. AFTN SEA BREEZES
WILL KEEP THE COASTLINE COOLER ONCE AGAIN.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
MORE PATCHY FOG WILL DEVELOP TONIGHT...DESPITE MORE HIGH THIN
CLOUDINESS CROSSING OVER SRN ME/NH. ONCE AGAIN...SOME MID AND
UPPER 40S PSBL FOR OVERNIGHT LOWS IN THE MTNS.
A REPEAT PERFORMANCE OCCURS ON SUNDAY. STILL THE POSSIBILITY
EXISTS FOR A BRIEF SHOWER OR TSTM OVER NH AND THE WRN MTNS OF ME.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
THE LARGE BROAD SURFACE AND UPPER RIDGE WILL MOVE OFF THE COAST
AND ALLOW A RETURN SSWLY FLOW EARLY NEXT WEEK. TEMPS WILL BE MILD
AND DEWPOINTS WILL BE ON THE RISE EARLY NEXT WEEK WITH CONDITIONS
POSSIBLY BECOMING RATHER MUGGY. BY LATE MON AND TUE THE UPPER
RIDGE BREAKS DOWN ALLOWING AN UPPER TROF TO APPROACH THE AREA FROM
THE WEST SETTING OFF SHWRS/TSTMS LATE MON AND MON NIGHT WITH SCT
SHWRS TUES. A SFC CDFNT ASSOC WITH THE UPPER TROF WILL MOVE THRU
BY LATE TUES OR EARLY WED BRINGING WITH IT A MUCH DRIER CANADIAN
AMS AND COOLER TEMPS FOR THE MID TO LATTER PART OF THE WEEK.
&&
.AVIATION /13Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM...VFR CONDITIONS WILL PREVAIL ACROSS THE REGION
THROUGHOUT THE PERIOD. SOME VALLEY FOG MAY DEVELOP TONIGHT OVER
FAVORED LOCATIONS RESULTING IN A FEW HOURS OF IFR/LIFR CONDITIONS
BEFORE BURNING OFF EARLY TOMORROW MORNING.
LONG TERM...GENERALLY VFR EXCEPT SHOWERS AND THUNDERSTORMS
POSSIBLE MONDAY AFTERNOON AND MONDAY NIGHT ALLOWING MVFR CONDS TO
DEVELOP...THEN A CHC OF SHWRS TUESDAY.
&&
.MARINE...
SHORT TERM...NO FLAGS EXPECTED
LONG TERM...GENERALLY LIGHT FLOW OVER THE WATERS CONTINUES. COLD
FRONT MOVES THROUGH TUESDAY.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...CEMPA
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
AREA FORECAST DISCUSSION
NWS GRAY ME
735 AM EDT SAT AUG 25 2012
.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER NORTHERN NEW ENGLAND AND THEN SHIFT
OFFSHORE THIS WEEKEND. GENERALLY DRY AND SEASONABLY WARM
CONDITIONS ARE EXPECTED THROUGH EARLY NEXT WEEK BEFORE A COLD
FRONT MOVES THROUGH LATE TUESDAY OR EARLY WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...
LATEST UPDATE IS FOR A DENSE FOG ADVISORY...GOOD THROUGH 9 AM.
THIS IS FOR SOUTHWEST MAINE AND EASTERN NEW HAMPSHIRE.
UPDATING THE GRIDS THIS MORNING TO EXPAND AREAS OF FOG ACROSS THE
REGION. SEVERAL AREAS HAVE FLIRTED WITH THE 1/4 MILE DENSE FOG
ADVISORY CRITERIA...BUT THIS HAS BEEN RELATIVELY BRIEF IN MOST
REGIONS. MAY ISSUE AN SPS TO ACCOUNT FOR ISOLD REGIONS OF DENSE
FOG FOR EARLY MORNING TRAVEL.
WILL STILL HAVE QUITE A FEW CLOUDS OVER SOUTHERN AREAS AFTER THE
MORNING FOG MIXES OUT. THIS IS REFLECTED CURRENTLY IN THE CLOUD
GRIDS. TEMPS MAY RUN A TAD COOLER THAN MOS OVER SOUTHERN LOCATIONS
DUE TO THE BKN...ALBIET HIGH CLOUD COVER.
PREV DISC...
A COUPLE CHALLENGES TO THE FCST ONCE AGAIN THIS MORNING.
AFTER MORNING FOG MIXES OUT...HIGH CLOUDS WITH A FEW EMBEDDED AC
WILL CONTINUE TO RIDE INTO THE RIDGE POSITIONED OVER NEW ENGLAND
AND OFF THE EASTERN SEABOARD. THIS MAY LIMIT TEMPS OVER SOUTHERN
ME/NH BY A FEW DEGS DURING THE AFTN HOURS. OTHERWISE...PARTLY TO
MOSTLY SUNNY CONDITIONS WILL PREVAIL NORTH OF THIS REGION THIS
MORNING.
DURING THE AFTN...SUFFICIENT ENOUGH INSTABILITY WILL ALLOW FOR A
SMALL CHANCE FOR A BRIEF SHOWER OVER WRN NH AND THE WRN MTNS OF
MAINE IN THE PROXIMITY AROUND THE PERIPHERY OF THE SURFACE RIDGE.
WITH LI VALUES DROPPING IN THIS AREA AND AMPLE SFC HEATING...THERE
IS ALSO A RISK OF A TSTM IN THIS REGION. LATEST HRRR MODEL CONTS
TO PICK UP ON THIS WIDELY SCT AFTN PCPN.
USED A BLEND OF MAV/MET MOS FOR AFTN MAX TEMPS. AFTN SEA BREEZES
WILL KEEP THE COASTLINE COOLER ONCE AGAIN.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
MORE PATCHY FOG WILL DEVELOP TONIGHT...DESPITE MORE HIGH THIN
CLOUDINESS CROSSING OVER SRN ME/NH. ONCE AGAIN...SOME MID AND
UPPER 40S PSBL FOR OVERNIGHT LOWS IN THE MTNS.
A REPEAT PERFORMANCE OCCURS ON SUNDAY. STILL THE POSSIBILITY
EXISTS FOR A BRIEF SHOWER OR TSTM OVER NH AND THE WRN MTNS OF ME.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
THE LARGE BROAD SURFACE AND UPPER RIDGE WILL MOVE OFF THE COAST
AND ALLOW A RETURN SSWLY FLOW EARLY NEXT WEEK. TEMPS WILL BE MILD
AND DEWPOINTS WILL BE ON THE RISE EARLY NEXT WEEK WITH CONDITIONS
POSSIBLY BECOMING RATHER MUGGY. BY LATE MON AND TUE THE UPPER
RIDGE BREAKS DOWN ALLOWING AN UPPER TROF TO APPROACH THE AREA FROM
THE WEST SETTING OFF SHWRS/TSTMS LATE MON AND MON NIGHT WITH SCT
SHWRS TUES. A SFC CDFNT ASSOC WITH THE UPPER TROF WILL MOVE THRU
BY LATE TUES OR EARLY WED BRINGING WITH IT A MUCH DRIER CANADIAN
AMS AND COOLER TEMPS FOR THE MID TO LATTER PART OF THE WEEK.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM...VFR CONDITIONS WILL PREVAIL ACROSS THE REGION
THROUGHOUT THE PERIOD. SOME VALLEY FOG MAY DEVELOP TONIGHT OVER
FAVORED LOCATIONS RESULTING IN A FEW HOURS OF IFR/LIFR CONDITIONS
BEFORE BURNING OFF EARLY TOMORROW MORNING.
LONG TERM...GENERALLY VFR EXCEPT SHOWERS AND THUNDERSTORMS
POSSIBLE MONDAY AFTERNOON AND MONDAY NIGHT ALLOWING MVFR CONDS TO
DEVELOP...THEN A CHC OF SHWRS TUESDAY.
&&
.MARINE...
SHORT TERM...NO FLAGS EXPECTED
LONG TERM...GENERALLY LIGHT FLOW OVER THE WATERS CONTINUES. COLD
FRONT MOVES THROUGH TUESDAY.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR MEZ012-
018>021-023>026.
NH...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR NHZ004-006-
010-013-014.
MARINE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAY ME
612 AM EDT SAT AUG 25 2012
.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER NORTHERN NEW ENGLAND AND THEN SHIFT
OFFSHORE THIS WEEKEND. GENERALLY DRY AND SEASONABLY WARM
CONDITIONS ARE EXPECTED THROUGH EARLY NEXT WEEK BEFORE A COLD
FRONT MOVES THROUGH LATE TUESDAY OR EARLY WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...
UPDATING THE GRIDS THIS MORNING TO EXPAND AREAS OF FOG ACROSS THE
REGION. SEVERAL AREAS HAVE FLIRTED WITH THE 1/4 MILE DENSE FOG
ADVISORY CRITERIA...BUT THIS HAS BEEN RELATIVELY BRIEF IN MOST
REGIONS. MAY ISSUE AN SPS TO ACCOUNT FOR ISOLD REGIONS OF DENSE
FOG FOR EARLY MORNING TRAVEL.
WILL STILL HAVE QUITE A FEW CLOUDS OVER SOUTHERN AREAS AFTER THE
MORNING FOG MIXES OUT. THIS IS REFLECTED CURRENTLY IN THE CLOUD
GRIDS. TEMPS MAY RUN A TAD COOLER THAN MOS OVER SOUTHERN LOCATIONS
DUE TO THE BKN...ALBIET HIGH CLOUD COVER.
PREV DISC...
A COUPLE CHALLENGES TO THE FCST ONCE AGAIN THIS MORNING.
AFTER MORNING FOG MIXES OUT...HIGH CLOUDS WITH A FEW EMBEDDED AC
WILL CONTINUE TO RIDE INTO THE RIDGE POSITIONED OVER NEW ENGLAND
AND OFF THE EASTERN SEABOARD. THIS MAY LIMIT TEMPS OVER SOUTHERN
ME/NH BY A FEW DEGS DURING THE AFTN HOURS. OTHERWISE...PARTLY TO
MOSTLY SUNNY CONDITIONS WILL PREVAIL NORTH OF THIS REGION THIS
MORNING.
DURING THE AFTN...SUFFICIENT ENOUGH INSTABILITY WILL ALLOW FOR A
SMALL CHANCE FOR A BRIEF SHOWER OVER WRN NH AND THE WRN MTNS OF
MAINE IN THE PROXIMITY AROUND THE PERIPHERY OF THE SURFACE RIDGE.
WITH LI VALUES DROPPING IN THIS AREA AND AMPLE SFC HEATING...THERE
IS ALSO A RISK OF A TSTM IN THIS REGION. LATEST HRRR MODEL CONTS
TO PICK UP ON THIS WIDELY SCT AFTN PCPN.
USED A BLEND OF MAV/MET MOS FOR AFTN MAX TEMPS. AFTN SEA BREEZES
WILL KEEP THE COASTLINE COOLER ONCE AGAIN.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
MORE PATCHY FOG WILL DEVELOP TONIGHT...DESPITE MORE HIGH THIN
CLOUDINESS CROSSING OVER SRN ME/NH. ONCE AGAIN...SOME MID AND
UPPER 40S PSBL FOR OVERNIGHT LOWS IN THE MTNS.
A REPEAT PERFORMANCE OCCURS ON SUNDAY. STILL THE POSSIBILITY
EXISTS FOR A BRIEF SHOWER OR TSTM OVER NH AND THE WRN MTNS OF ME.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
THE LARGE BROAD SURFACE AND UPPER RIDGE WILL MOVE OFF THE COAST
AND ALLOW A RETURN SSWLY FLOW EARLY NEXT WEEK. TEMPS WILL BE MILD
AND DEWPOINTS WILL BE ON THE RISE EARLY NEXT WEEK WITH CONDITIONS
POSSIBLY BECOMING RATHER MUGGY. BY LATE MON AND TUE THE UPPER
RIDGE BREAKS DOWN ALLOWING AN UPPER TROF TO APPROACH THE AREA FROM
THE WEST SETTING OFF SHWRS/TSTMS LATE MON AND MON NIGHT WITH SCT
SHWRS TUES. A SFC CDFNT ASSOC WITH THE UPPER TROF WILL MOVE THRU
BY LATE TUES OR EARLY WED BRINGING WITH IT A MUCH DRIER CANADIAN
AMS AND COOLER TEMPS FOR THE MID TO LATTER PART OF THE WEEK.
&&
.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM...VFR CONDITIONS WILL PREVAIL ACROSS THE REGION
THROUGHOUT THE PERIOD. SOME VALLEY FOG MAY DEVELOP TONIGHT OVER
FAVORED LOCATIONS RESULTING IN A FEW HOURS OF IFR/LIFR CONDITIONS
BEFORE BURNING OFF EARLY TOMORROW MORNING.
LONG TERM...GENERALLY VFR EXCEPT SHOWERS AND THUNDERSTORMS
POSSIBLE MONDAY AFTERNOON AND MONDAY NIGHT ALLOWING MVFR CONDS TO
DEVELOP...THEN A CHC OF SHWRS TUESDAY.
&&
.MARINE...
SHORT TERM...NO FLAGS EXPECTED
LONG TERM...GENERALLY LIGHT FLOW OVER THE WATERS CONTINUES. COLD
FRONT MOVES THROUGH TUESDAY.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1112 AM EDT SAT AUG 25 2012
.SYNOPSIS...
A LOW PRESSURE SYSTEM LIFTS NORTH ACROSS SOUTHERN VIRGINIA THIS
AFTERNOON..AS HIGH PRESSURE REMAINS ANCHORED OVER NEW ENGLAND.
THIS AREA OF LOW PRESSURE WILL DISSIPATE SUNDAY OVER THE CENTRAL
APPALACHIANS AS HIGH PRESSURE RETURNS TO THE REGION EARLY NEXT
WEEK. A COLD FRONT WILL APPROACH THE REGION BY MIDWEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A VERY WET MRNG FOR MANY AREAS OF FA. WK SFC LO PRES LIFING INTO
XTRM SCNTRL VA RIGHT NOW WILL BE SLO TO CONT TO TRACK NNW THIS
AFTN. SVRL BANDS OF MOD/HVY RA ASSOCIATED W/ TSTMS MOVG INTO ERN
VA AND TWD THE CAPITAL CITY. SVRL LOCATIONS IN SE/SCNTRL VA AND
FAR INTR NE NC HAVE RECEIVED 3-6 IN OF RA...INCLDG HERE AT THE
OFFICE. TRIMMED POPS FOR SE PORTION OF FA AS DRIER AIR MOVG N
INVOF CST...HIGHEST POPS (60-80%) INTO MID AFTN FOR THE FAR W AND
ACRS NRN 1/3RD OF FA. 14Z/25 RUC SUGGESTS HEAVIEST RA WILL BCM
CONCENTRATED IN AREAS FM RIC ON E AND NE THROUGH 18Z/25.
HI TEMPS L/M80S SE...TO M70S NNW.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
THE MID-LEVEL WAVE STEADILY DISSIPATES TONIGHT THROUGH SUNDAY OVER
THE CENTRAL APPALACHIANS...WITH SHORTWAVE RIDGING PREVAILING BY
MONDAY AHEAD OF A COLD FRONT OVER THE OHIO VALLEY AND ISAAC WELL TO
THE SOUTH NEAR THE GULF COAST. THE CHANCE OF SHOWERS DIMINISHES AS
WELL ALONG WITH AT LEAST A PARTIAL CLEARING TREND. HIGH TEMPERATURES
SHOULD REACH THE MID TO UPPER 80S SUNDAY FOLLOWED BY UPPER 80S TO
AROUND 90 MONDAY. LOW TEMPERATURES SHOULD BE IN THE MID TO UPPER 60S.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
PLEASE FOLLOW THE LATEST FCST FROM THE NHC FOR DETAILS ON TS ISAAC.
LATEST FCST FOR ISAAC CONTINUES TO FAVOR A TRACK INTO THE GULF OF
MEXICO AND GENLY WELL TO THE SW OF THE AKQ CWA. ANY REMNANTS OF
ISAAC WOULD NOT APPEAR TO AFFECT THE LOCAL AREA UNTIL TUE NGT/WED AT
THE EARLIEST...WITH THE MAIN POTENTIAL IMPACT BEING HEAVY RAIN.
MID-LVL S/W TROF AND ASSOCIATED FRONTAL BNDRY APPROACH FROM THE WEST
ON TUE LEADING TO A CHC FOR RAIN. MAIN ISSUE DURING THE WEEK IS HOW
STRONG THE TROF OVER THE EASTERN CONUS WILL BE...WILL IT BE
AMPLIFIED ENUF TO PICK UP ISAAC AND ADVANCE IT TOWARDS THE MID
ATLANTIC (12Z GFS SOLUTION)...OR WILL THE TROF BE WEAKER AND MORE
PROGRESSIVE...LEADING TO ISAAC MISSING THE TROF AND INSTEAD HEADING
IN A N/NW DIRECTION FOLLOWING LANDFALL (12Z ECMWF SOLUTION)...WHICH
MEANS SFC HI PRES AND MAINLY DRY CONDITIONS OVER THE MID ATLANTIC
THROUGH NEXT FRI. WILL CONTINUE A BLENDED FORECAST DUE TO THE LARGE
UNCERTAINTY WITH A BIT MORE WEIGHT PUT ON THE ECMWF...NO HIGHER THAN
30-40% POPS THRU THE PERIOD AND HIGH TEMPS RANGING THRU THE 80S OVER
THE COURSE OF THE WEEK.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
LO PRES JUST OFF THE NC CST WILL MOVE SLOWLY N AND INTO ERN
PORTIONS OF THE AREA TDY INTO SUN MORNG. THIS WILL RESULT IN MVFR
(ISLTD IFR) CONDITIONS WITH SHOWERS ACRS THE AREA. AREAS OF IFR
FOG AND STRATUS WILL BE POSSIBLE SUN AND MON MORNGS...OTHRWISE
EXPECTING MAINLY DRY CONDITIONS FOR SUN AFTN THRU MON.
&&
.MARINE...
HIGH RISK OF RIP CURRENTS IN EFFECT FOR TODAY WITH STRONG ONSHORE
FLOW AND HIGH SWELL PERIOD EXPECTED.
MAINTAINED SCA`S THRU THIS AFTN/EVENG FOR THE CHES BAY AND THE
LWR JAMES RIVER NEAR HAMPTON ROADS BRIDGE TUNNEL...AND THRU THIS
AFTN OR THRU LATE TNGT FOR THE CSTL WTRS...DUE TO STRNG NE OR E
WNDS CAUSED BY PRESSURE GRADIENT BETWEEN HI PRES JUST OFF THE NEW
ENGLAND CST AND LO PRES MOVNG NWRD FM JUST OFF THE NC CST. WAVES
OVR THE CHES BAY WILL BLD TO 3-5 FT WITH SEAS OVR THE COASTAL
WTRS BLDNG TO 5-6 FT. AFOREMENTIONED LO PRES WEAKENS AND
DISSIPATES OVR VA SUN MORNG. A LOT OF UNCERTAINTY STILL WITH THE
EVENTUAL TRACK OF TS ISAAC (SEE LATEST NHC FCST FOR DETAILS).
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ632-
634-638-656-658.
SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ630-
631.
SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR ANZ650-652-654.
&&
$$
SYNOPSIS...AJZ/ALB/SAM
NEAR TERM...AJZ/ALB
SHORT TERM...AJZ
LONG TERM...MAS
AVIATION...TMG
MARINE...TMG
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1017 AM CDT SAT AUG 25 2012
.DISCUSSION...
15 UTC SURFACE ANALYSIS SHOWS A COLD FRONT FROM BAUDETTE TO NEAR
WAHPETON. ALONG THIS LINE IS A BAND OF SHOWERS AND ISOLATED
THUNDERSTORMS...MOVING TO THE EAST-NORTHEAST AROUND 30 KTS. EXPECT
THE MAJORITY OF THIS PRECIPITATION TO MOVE OUT OF THE FORECAST AREA
BY 18 UTC. SOME RE-DEVELOPMENT IS POSSIBLE ACROSS THE FAR EAST THIS
AFTERNOON...BUT ALL OTHER AREAS WILL BE DRY AND SUNNY. NOT EVEN A
HINT OF THERMAL CUMULUS WITH CONVECTIVE TEMPERATURES IN THE 90S TO
NEAR 100 DEGREES. TRIMMED BACK EDGE OF POPS THE REST OF THE DAY
WITH ONLY A 20 TO 30 PERCENT CHANCE OF SHOWERS AND STORMS FROM
BEMIDJI TO PARK RAPIDS AND POINTS EAST THIS AFTERNOON. HIGHEST
INSTABILITY AXIS HAS MOVED INTO THE MN ARROWHEAD AND DO NOT EXPECT
ANY SEVERE WEATHER THE REST OF THE DAY.
STRONG COLD AIR ADVECTION BEHIND THE FRONT WILL RESULT IN
TEMPERATURES 10 TO 15 DEGREES COOLER THAN YESTERDAY WITH AFTERNOON
HIGHS IN THE MID 70S TO NEAR 80 DEGREES. BOUNDARY LAYER DEEPENS TO
BETWEEN 850 AND 750 HPA THIS AFTERNOON WITH 20 TO 30 KTS TO MIX TO
THE SURFACE. EXPECT BREEZY WESTERLY WINDS...ESPECIALLY ACROSS THE
DEVILS LAKE BASIN. DEVILS LAKE AND LANGDON ARE ALREADY GUSTING TO
25 PLUS KNOTS...BUT 14 UTC RAP SHOWS WINDS ALOFT DECREASING A BIT
THROUGH THE DAY...SO DO NOT EXPECT THE NEED FOR ANY KIND OF
ADVISORY.
&&
.AVIATION...
THE FRONTAL BOUNDARY THAT WAS OVER THE RIVER VALLEY EARLY THIS
MORNING HAS CLEARED ALL TAF SITES BY MID MORNING WITH THE
EXCEPTION OF KBJI. TSRA CONTINUE TO MOVE EASTWARD IMPACTING KBJI
BETWEEN 15Z AND 17Z. KBJI WILL CONT TO HAVE MVFR CIGS THROUGH THE
DAY WHILE THE REST OF THE SITES WILL BE VFR. NW WINDS THAT WERE
OCCURRING EARLIER WILL PRIMARILY BE WLY FOR ALL SITES THIS AFTN.
EXPECT WIND GUST AT KDVL TO REMAIN ABOVE 25 KTS UNTIL 00Z.
&&
.PREV DISCUSSION... /ISSUED 430 AM CDT SAT AUG 25 2012/
SHORT TERM.../TODAY THROUGH MONDAY NIGHT.
WATER VAPOR LOOP INDICATED UPPER LEVEL TROUGH OVER SASK. UPPER LOW
WILL MOVE OVER HUDSON BAY BY SUN. COLD FRONT HAS MOVED INTO EASTERN
ND AND WILL CONTINUE MOVING EAST TODAY.
THUNDERSTORMS WERE OCCURRING IN 700 HPA THETA-E RIDGE. SURFACE WIND
SHIFT REMAINS TO THE WEST AND IS FORECAST TO SWEEP ACROSS THE
FORECAST AREA THIS MORNING. HOWEVER FRONT SLOWS DOWN THIS AFTERNOON
OVER SOUTHEAST ZONES. WILL KEEP POPS FARTHER WEST THIS AFTERNOON.
ELEVATED SHOWERS OVER WESTERN ND WILL MOVE EAST TODAY.
LITTLE OR NO PRECIPITATION EXPECTED REST OF SHORT TERM. TEMPERATURES
WERE TWEAKED. COOLER FOR MON NIGHT WITH UPPER RIDGE BUILDING TO THE
WEST.
LONG TERM (TUE THROUGH FRI)...
THE EXTENDED PERIOD WILL START OUT WARM WITH TEMPS WELL ABOVE NORMAL
WITH AN UPPER RIDGE...AND 850MB TEMPS AROUND +25C IN THE VALLEY ON
WED. THERE WILL BE A COLD FRONT THAT MOVES THROUGH THE REGION WED
NIGHT AND THU...AND THERE WILL BE SOME LOW CHANCES FOR SHOWERS AND
STORMS. NOT TOO EXCITED ABOUT CONVECTION THOUGH WITH MOISTURE RETURN
IN QUESTION...BUT WILL LEAVE IN LOW CHANCES FOR PRECIP WED NIGHT INTO
THU NIGHT. TEMPS SHOULD COOL TO NEAR NORMAL BY THE END OF NEXT WEEK
WITH DRY WEATHER EXPECTED ONCE AGAIN.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
ROGERS/FRAZIER/HOPPES/DK
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1043 AM CDT SAT AUG 25 2012
.UPDATE...
SEE MORNING UPDATE.
&&
.DISCUSSION...
12Z SOUNDINGS SHOWED PW VALUES BETWEEN 1.9 INCHES SOUTHWEST TO
2.30 INCHES OVER THE EXTREME EAST. CONVECTIVE TEMPS ARE BETWEEN 83
DEGREES OVER THE EAST AND AROUND 88 DEGREES SOUTHWEST. 250 MB
WINDS REMAIN DIVERGENT SO FEEL PARAMETERS ARE IN PLACE FOR A
DECENT CHANCE OF SHRA/TSRA TODAY. TEMPS AT 10 AM ARE ALREADY IN
THE MID AND UPPER 80S SO FEL COVERAGE WILL BEGIN TO FILL IN. THE
LATEST RAP MODEL SHOWS PRECIP EXPANDING INTO THE NORTHWEST ZONES
LATE THIS AFTN AND AM TEMPTED TO BOOST POPS BUT WILL WATCH TRENDS
BEFORE MAKING THAT CALL. REST OF FCST LOOKS ON TRACK. 43
&&
.PREV DISCUSSION... /ISSUED 626 AM CDT SAT AUG 25 2012/
AVIATION...
SCATTERED SHOWERS OFFSHORE CONTINUE TO APPROACH THE COAST WHILE
ADDITIONAL SHOWERS ARE FINALLY BEGINNING TO DEVELOP INLAND NEAR
GALVESTON BAY. FURTHER NORTH...AM A BIT CONCERNED THAT VSBYS FOR
CXO WILL DROP SHARPLY OVER THE FIRST HOUR OF THE TAF PERIOD AS
SKIES CLEAR AND WINDS HAVE BECOME CALM. OTHERWISE VFR CONDITIONS
SHOULD PREVAIL THROUGH THE TAF PERIOD WITH ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS THROUGH THE AFTERNOON HOURS TODAY.
COVERAGE SHOULD BE A BIT LESS THAN YESTERDAY AND CONFINED MAINLY
TO THE EASTERN TWO THIRDS OF THE CWA...THUS WILL NOT CARRY A
MENTION OF VCTS FOR CLL THIS AFTERNOON. WINDS OVERNIGHT INTO
SUNDAY SHOULD BE LOWER THAN TONIGHT AS THE PRESSURE GRADIENT
BEGINS TO RELAX ACROSS THE REGION. 38
PREV DISCUSSION... /ISSUED 430 AM CDT SAT AUG 25 2012/
DISCUSSION...
IR SATELLITE LESS CLOUDY AND RADAR LOOPS LESS ACTIVE THIS MORNING
BUT A FEW SHRA ARE NOTED OVER THE WATER AND OVER JACKSON AND
SOUTHWESTERN MATAGORDA COUNTIES AT 09Z. 00Z 250MB MANUAL ANALYSIS
INDICATES HIGH PRESSURE OVER BAJA CA RIDGING TO THE NW OVER
TX...BELOW AT 500MB VERY WEAK TROUGH NOTED FROM KHGX TO KBRO. FROM
SFC-700MB RIDGE AXIS FROM ATLANTIC SUBTROPICAL HIGH IS IN PLACE
WITH SE TX ON THE FRINGE OF THE CIRCULATION. PWAT GRADIENT RUNS
FROM 1.6 IN WESTERN PART OF FA TO NEAR 2 INCHES EAST OF GLS BAY.
GFS FORECASTS ONSHORE FLOW TODAY WITH A GENERAL INCREASE IN PWATS.
HAVE FINE TUNED PCPN CHANCES TODAY FROM PREVIOUS FORECAST WITH
HIGHER CHANCES AGAIN TO THE SOUTHEAST IN GALVESTON AND CHAMBERS
COUNTIES AND OFFSHORE WATERS. NOT EXPECTING AVERAGE RAINFALL
AMOUNTS TO BE AS HIGH AS YESTERDAY WITH GREATEST AMOUNTS IN THE
SOUTHEAST...PERHAPS AVERAGING 0.25 TO 0.50 INCH LOCALLY. GIVEN
KCLL REACHING 95 YESTERDAY MAX TEMPS IN THE NORTHWEST WERE RAISED
SLIGHTLY TODAY.
TOMORROW MEAN SFC-700MB RIDGING MOVES NORTH TAPERING OFF THE
MOISTURE TAP. GFS SPLITS A PIECE OF THE UPPER TROUGH NOW OVER THE
TX PANHANDLE TO OUR WEST TOMORROW SO CANNOT RULE OUT PCPN CHANCES
BUT THEY ARE LOWER THAN TODAY. BY MONDAY ISAAC IS FORECAST BY NHC
TO BE IN THE FAR EASTERN GULF. THIS PUTS SE TX IN A GENERALLY DEEP
OFFSHORE FLOW REGIME. INTERESTING FLIES IN THE OINTMENT FOR
TUESDAY IS A WESTERLY MOVING 250MB LOW THAT BREAKS OFF THE TROUGH
NOW IN THE SOUTHEASTERN US AND SOME RELATIVELY HIGH PWAT AIR ALONG
AND AHEAD OF A FRONTAL ZONE TO OUR NORTH. ECM/GFS MOS POPS ARE
QUITE HIGH ON TUESDAY (40 TO NEAR 50 PERCENT) BUT GIVEN THE USUAL
PATTERN OFF TO THE NORTHWEST OF TROPICAL SYSTEMS IN THE GULF THIS
PCPN CHANCE SEEMS HIGH SO WILL COMPROMISE BY LEAVING OUR 20
PERCENT FORECAST IN PLACE. WILL NEED TO CONTINUE TO MONITOR THIS
AS TUESDAY COULD BE BRIEFLY WETTER. WED THOUGH THE NEXT WEEKEND
LOOK VERY DRY AND TEMPERATURES WILL BE WARMING. GFS ENSEMBLE MEAN
MOS IS HIGHER THAN GFS LONG RANGE MOS (MEX) AND THE EXPERIMENTAL
ECM MOS IS EVEN HIGHER. AS A RESULT MAX TEMPS ON THU-FRI WERE
INCREASED.
CORRECTED FOR GRAMMAR. 04
MARINE...
SURFACE PRESSURE GRADIENT REMAINS RATHER TIGHT ACROSS EASTERN TEXAS
AND LOUISIANA THIS MORNING KEEPING WINDS ACROSS THE COASTAL WATERS
AT AROUND 15KTS...THUS WILL KEEP THE CURRENT ADVISORY FLAGS IN PLACE
THROUGH MIDDAY. WINDS SHOULD BEGIN TO EASE ON SUNDAY BEFORE BECOMING
OFFSHORE BY TUESDAY IN RESPONSE TO ISAAC MOVING INTO THE EASTERN
GULF OF MEXICO. AT THIS TIME IT APPEARS THAT ISAAC WILL REMAIN WELL
TO THE EAST OF OUR AREA WITH MARITIME IMPACTS TO THE UPPER TEXAS
COAST LIMITED TO 3 TO 4 FOOT SEAS ACROSS THE OFFSHORE WATERS AND
SLIGHTLY BELOW NORMAL TIDE LEVELS DUE TO NORTHERLY WINDS OF AROUND
10 TO 15 KTS.
ALTHOUGH ISAAC IS NOT FORECAST TO DIRECTLY AFFECT THE UPPER TEXAS
COASTAL WATERS MARINERS ARE URGED TO CONTINUE MONITORING NHC
FORECASTS AND ADVISORIES REGARDING THE SYSTEM AS IT MOVES INTO THE
GULF OF MEXICO EARLY NEXT WEEK. 38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 93 75 94 75 95 / 20 20 20 10 20
HOUSTON (IAH) 91 76 93 75 94 / 40 20 30 10 30
GALVESTON (GLS) 88 79 90 80 91 / 50 20 30 10 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 7 PM CDT THIS EVENING
FOR THE FOLLOWING ZONES: MATAGORDA BAY...WATERS FROM
FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...
WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20
NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM...
WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.
&&
$$
DISCUSSION...43
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
440 PM EDT SAT AUG 25 2012
.SYNOPSIS...
20Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS OUR REGION LOCATED UNDER A
MID/UPPER LEVEL WEAKNESS IN THE HEIGHT FIELD TO THE WEST OF A RIDGE
OFF THE SE CONUS. STILL DEALING WITH A WEAK DISTURBANCE NEAR THE
FLORIDA STRAITS THAT IS SUPPORTING A BROAD AREA OF RAIN/THUNDER OVER
THE SE/S FL PENINSULA. MOST OF THE RAINFALL SHOULD CONTINUE TO
REMAIN EAST AND SOUTH OF OF LEE/CHARLOTTE COUNTIES AS SPEED
CONVERGENCE FOCUS WEAKENS INLAND FROM THE EAST COAST. A FEW
ADDITIONAL SCT SHOWERS ARE ADVANCING WESTWARD ACROSS THE PENINSULA
AND WILL EFFECT THE TAMPA BAY AREA UP THROUGH THE NATURE COAST ZONES
THE NEXT SEVERAL HOURS. SHOULD SEE THESE STORMS DISSIPATE AS WE HEAD
INTO THE EVENING HOURS. ANY SHOWERS/STORMS THAT DO OCCUR IN THE
FORECAST AREA ARE NOT ASSOCIATED WITH ANY OUTER-BANDS OF ISAAC. THIS
IS A SEPARATE MID-LEVEL FEATURE WHICH WILL BE PASSING OUT IN THE SE
GULF LATER TODAY/TONIGHT.
AT THE SURFACE...FORECAST AREA RESIDES BETWEEN A 1022MB RIDGE CENTER
OVER THE CAROLINAS...AND THE LOW PRESSURE ASSOCIATED WITH TS ISAAC
DOWN OVER THE EASTERN TIP OF CUBA. THE LOCAL GRADIENT IS TIGHTENING
BETWEEN THESE 2 FEATURES. A MORE MESO-SCALE ANALYSIS SHOWS A FAIRLY
SHARP INVERTED TROUGH ALONG THE FLORIDA EAST COAST WHICH IS ALSO
HELPING TO FOCUS THE LIFT FOR SHOWERS/STORMS TO OUR EAST AND SOUTH.
&&
.SHORT TERM (TONIGHT THROUGH MONDAY NIGHT)...
TONIGHT...
CURRENT THINKING IS THAT RAIN CHANCES WILL FALL (EVEN FOR
THE FAR SOUTH) INTO THE OVERNIGHT HOURS AS THE DISTURBANCE MENTIONED
ABOVE EXITS THE REGION. WITH SOME RESIDUAL LINGERING SYNOPTIC
SUPPORT FOR LIFT AND ADDED SPEED CONVERGENCE SHOWERS MOVING INLAND
FROM THE FL EAST COAST WILL KEEP A LOW END CHANCE FOR SHOWERS IN THE
GRIDS DOWN TOWARD FORT MYERS. ELSEWHERE AFTER ANY SCT EVENING
SHOWERS HAVE FADED...WILL ANTICIPATE A MAINLY DRY OVERNIGHT.
SUNDAY...
WILL BE WATCHING TROPICAL STORM ISAAC CONTINUE TO MOVE TOWARD THE
NORTHWEST ALONG OR NEAR THE NORTHERN COAST OF CUBA AND THEN THROUGH
THE FLORIDA STRAITS. MODEL GUIDANCE IS FAIRLY CLUSTERED THROUGH THIS
POINT BRINGING THE STORM CENTER TO NEAR THE FLORIDA KEYS SUNDAY
EVENING. OUTER RAINBANDS ASSOCIATED WITH ISAAC ARE EXPECTED TO BEGIN
IMPACTING ZONES TO THE SOUTH OF I-4 BEFORE THE END OF THE DAY WITH
THE HEAVIEST AND MOST WIDESPREAD RAINFALL POTENTIAL INCREASING THE
FURTHER SOUTH AND SOUTHEAST ONE TRAVELS. IN ADDITION TO THESE OUTER
RAINBANDS...THE LOCAL GRADIENT WILL CONTINUE TO TIGHTEN BETWEEN THE
STORM TO OUR SOUTH AND A RIDGE OF HIGH PRESSURE TO THE NORTH. JUST
HOW TIGHT THE GRADIENT EVENTUALLY BECOMES WILL DEPEND ON THE
STRENGTH/ORGANIZATION OF ISAAC...BUT IT IS LIKELY TO BE A RATHER
GUSTY DAY. THE CURRENT FORECAST WOULD SUPPORT SEEING TROPICAL STORM
FORCE GUSTS DOWN TOWARD LEE COUNTY BEFORE THE DAY IS OVER ASSOCIATED
WITH SOME OF THE RAINBANDS. AROUND THE TAMPA BAY AREA AND NORTHWARD
UP THE NATURE COAST...A FEW SHOWERS/ISOLATED STORMS ARE POSSIBLE
DURING THE AFTERNOON...HOWEVER IN GENERAL SUNDAY DOES NOT LOOK TO BE
A WET DAY THIS FAR NORTH AND WEST.
SUNDAY NIGHT...ISAAC IS FORECAST TO PROCEED INTO THE SOUTHEAST GULF
OF MEXICO. IT WILL BE DURING THIS PERIOD THAT BOTH THE HEAVIER
RAINBANDS AND POTENTIAL FOR TROPICAL STORM FORCE WINDS WILL BE
EXPANDING NORTHWARD INTO THE TAMPA BAY/I-4 CORRIDOR. FOR OUR
SOUTHERN COASTAL ZONES TO THE SOUTH OF SARASOTA...THIS IS WHEN WE
MIGHT BEGIN TO SEE SOME POTENTIAL SURGE PROBLEMS AS WELL AS THE
STORM CENTER PASSES AND PREVIOUS OFFSHORE WINDS COME AROUND MORE TO
THE SOUTH AND SOUTHWEST. PLEASE SEE THE LATEST HURRICANE LOCAL
STATEMENT (MIAHLSTBW) ISSUED BY THIS OFFICE FOR MORE SURGE
INFORMATION FOR LEE AND CHARLOTTE COUNTIES.
MONDAY/MONDAY NIGHT...ISAAC IS FORECAST TO BE MOVING TOWARD THE
NORTHWEST ACROSS THE EASTERN GULF OF MEXICO. THERE REMAINS SOME
DIFFERENCE IN THE GUIDANCE REGARDING THE TRACK OF ISAAC AND JUST HOW
FAR OFF THE FLORIDA WEST COAST THE STORM WILL PASS. AT THIS TIME THE
THREAT FOR PERIODS OF HEAVY RAIN AND TROPICAL STORM FORCE WINDS
REMAIN IN THE GRIDS. THE POTENTIAL FOR SOME COASTAL PROBLEMS RELATED
TO SURGE WILL ALSO BE DEVELOPING UP THE COAST TOWARD TAMPA BAY AND
THE NATURE COAST. BASED ON THE CURRENT UNCERTAINTY IN THE STORM
TRACK AND INTENSITY...THE FORECAST WILL CONTINUE TO BE REFINED WITH
FUTURE HURRICANE CENTER ADVISORIES.
ONE FINAL NOTE...DEPENDING ON THE TRACK OF ISAAC...FLOOD WATCHES MAY
BECOME NECESSARY FOR ALL OR PORTIONS OF THE AREA LATER TONIGHT OR
SUNDAY.
&&
.AVIATION...
A FEW STORMS ARE DEVELOPING OVER THE INTERIOR AND WILL MOVE WESTWARD
TOWARD THE TERMINALS THIS AFTERNOON. COVERAGE IS LOW SO NO TEMPO
GROUPS PLANNED AT THIS TIME. OTHERWISE STILL VFR NEXT 24 HOURS WITH
MAIN IMPACTS FROM ISAAC HOLDING OFF UNTIL AFTER 18Z SUNDAY.
&&
.MARINE...
TROPICAL STORM OR HURRICANE WATCHES HAVE BEEN ISSUED FOR THE COASTAL
WATERS FROM BONITA BEACH TO THE SUWANNEE RIVER. THE FORECAST WATERS
WILL REMAIN BETWEEN A RIDGE OF HIGH PRESSURE TO OUR NORTH AND
TROPICAL STORM ISAAC APPROACHING FROM THE SOUTHEAST. THE GRADIENT
BETWEEN THESE 2 SYSTEMS WILL CONTINUE TO TIGHTEN THROUGH SUNDAY WITH
ISAAC FORECAST TO MOVE INTO AND THROUGH THE EASTERN GULF OF MEXICO
DURING THE EARLY PORTION OF THE WEEK. FOR ADDITIONAL INFORMATION ON
TROPICAL STORM ISAAC...SEE THE LATEST ADVISORIES BEING ISSUED BY THE
NATIONAL HURRICANE CENTER.
&&
.HYDROLOGY...
FLOOD WARNINGS CONTINUE ON THE LITTLE MANATEE RIVER AND CYPRESS
CREEK. THE GROUND REMAINS SATURATED FROM RECENT HEAVY RAINS...AND
ADDITIONAL HEAVY RAIN EXPECTED FROM T.S. ISAAC MAY CAUSE
SIGNIFICANT FLOODING OF RIVERS OVER WEST CENTRAL FLORIDA MONDAY
INTO THE MIDDLE OF NEXT WEEK. FLOODING OF LOW LYING AND FLOOD
PRONE AREAS...WITH SIGNIFICANT FLOODING OF STREETS IN URBAN AREAS
IS POSSIBLE. THE GREATEST THREAT WILL BE SUNDAY NIGHT THROUGH
MONDAY NIGHT...BUT COULD EXTEND INTO TUESDAY OVER THE NORTHERN
HALF OF THE AREA DEPENDING ON THE EVENTUAL TRACK OF ISAAC.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 76 90 78 84 / 20 50 70 70
FMY 75 86 77 85 / 30 90 80 70
GIF 74 91 75 85 / 20 50 70 70
SRQ 75 91 78 87 / 20 50 70 70
BKV 70 90 79 86 / 20 50 70 70
SPG 78 89 79 85 / 20 40 70 70
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...TROPICAL STORM WATCH FOR CHARLOTTE-DESOTO-HARDEE-HIGHLANDS-
HILLSBOROUGH-LEE-MANATEE-PINELLAS-POLK-SARASOTA.
GULF WATERS...TROPICAL STORM WATCH FOR ENGLEWOOD TO TARPON SPRINGS
OUT 20 NM-TAMPA BAY WATERS-TARPON SPRINGS TO SUWANNEE
RIVER OUT 20 NM-TARPON SPRINGS TO SUWANNEE RIVER OUT 20 TO 60
NM.
HURRICANE WATCH FOR BONITA BEACH TO ENGLEWOOD OUT 20 NM-
BONITA BEACH TO ENGLEWOOD OUT 20 TO 60 NM-ENGLEWOOD
TO TARPON SPRINGS OUT 20 TO 60 NM.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WEATHER...MROCZKA
HYDROLOGY...OGLESBY
AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
254 PM EDT SAT AUG 25 2012
.SYNOPSIS...
A LOW PRESSURE SYSTEM LIFTS NORTH ACROSS SOUTHERN VIRGINIA THIS
AFTERNOON..AS HIGH PRESSURE REMAINS ANCHORED OVER NEW ENGLAND.
THIS AREA OF LOW PRESSURE WILL DISSIPATE SUNDAY OVER THE CENTRAL
APPALACHIANS AS HIGH PRESSURE RETURNS TO THE REGION EARLY NEXT
WEEK. A COLD FRONT WILL APPROACH THE REGION BY MIDWEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A VERY WET MRNG FOR MANY AREAS OF FA. WK SFC LO PRES LIFING INTO
XTRM SCNTRL VA RIGHT NOW WILL BE SLO TO CONT TO TRACK NNW THIS
AFTN. SVRL BANDS OF MOD/HVY RA ASSOCIATED W/ TSTMS MOVG INTO ERN
VA AND TWD THE CAPITAL CITY. SVRL LOCATIONS IN SE/SCNTRL VA AND
FAR INTR NE NC HAVE RECEIVED 3-6 IN OF RA...INCLDG HERE AT THE
OFFICE. TRIMMED POPS FOR SE PORTION OF FA AS DRIER AIR MOVG N
INVOF CST...HIGHEST POPS (60-80%) INTO MID AFTN FOR THE FAR W AND
ACRS NRN 1/3RD OF FA. 14Z/25 RUC SUGGESTS HEAVIEST RA WILL BCM
CONCENTRATED IN AREAS FM RIC ON E AND NE THROUGH 18Z/25.
HI TEMPS L/M80S SE...TO M70S NNW.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
THE MID-LEVEL WAVE STEADILY DISSIPATES TONIGHT THROUGH SUNDAY OVER
THE CENTRAL APPALACHIANS...WITH SHORTWAVE RIDGING PREVAILING BY
MONDAY AHEAD OF A COLD FRONT OVER THE OHIO VALLEY AND ISAAC WELL TO
THE SOUTH NEAR THE GULF COAST. THE CHANCE OF SHOWERS DIMINISHES AS
WELL ALONG WITH AT LEAST A PARTIAL CLEARING TREND. HIGH TEMPERATURES
SHOULD REACH THE MID TO UPPER 80S SUNDAY FOLLOWED BY UPPER 80S TO
AROUND 90 MONDAY. LOW TEMPERATURES SHOULD BE IN THE MID TO UPPER 60S.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
PLEASE FOLLOW THE LATEST FCST FROM THE NHC FOR DETAILS ON TS ISAAC.
LATEST FCST FOR ISAAC CONTINUES TO FAVOR A TRACK INTO THE GULF OF
MEXICO AND GENLY WELL TO THE SW OF THE AKQ CWA. ANY REMNANTS OF
ISAAC WOULD NOT APPEAR TO AFFECT THE LOCAL AREA UNTIL TUE NGT/WED AT
THE EARLIEST...WITH THE MAIN POTENTIAL IMPACT BEING HEAVY RAIN.
MID-LVL S/W TROF AND ASSOCIATED FRONTAL BNDRY APPROACH FROM THE WEST
ON TUE LEADING TO A CHC FOR RAIN. MAIN ISSUE DURING THE WEEK IS HOW
STRONG THE TROF OVER THE EASTERN CONUS WILL BE...WILL IT BE
AMPLIFIED ENUF TO PICK UP ISAAC AND ADVANCE IT TOWARDS THE MID
ATLANTIC (12Z GFS SOLUTION)...OR WILL THE TROF BE WEAKER AND MORE
PROGRESSIVE...LEADING TO ISAAC MISSING THE TROF AND INSTEAD HEADING
IN A N/NW DIRECTION FOLLOWING LANDFALL (12Z ECMWF SOLUTION)...WHICH
MEANS SFC HI PRES AND MAINLY DRY CONDITIONS OVER THE MID ATLANTIC
THROUGH NEXT FRI. WILL CONTINUE A BLENDED FORECAST DUE TO THE LARGE
UNCERTAINTY WITH A BIT MORE WEIGHT PUT ON THE ECMWF...NO HIGHER THAN
30-40% POPS THRU THE PERIOD AND HIGH TEMPS RANGING THRU THE 80S OVER
THE COURSE OF THE WEEK.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
PLENTY OF LOW LEVEL MOISTURE WILL RESULT IN MARGINAL VFR CEILINGS
THROUGH MOST OF THE TAF PERIOD. SOME IFR PSBL ESPECIALLY AT PHF
WHERE SEVERAL INCHES OF RAIN FELL EARLY SATURDAY. AREAS OF RAIN AND
TSTMS WILL SHIFT TO THE NORTH THROUGH SATURDAY EVENING. WINDS WILL
BE GENERALLY FROM THE SOUTHEAST AS SURFACE LOW STALLS OVER SOUTHERN
VIRGINIA. CONDITIONS SLOWLY IMPROVES BY MIDDAY SUNDAY.
OUTLOOK...MAINLY DRY WEATHER IS FORECAST SUNDAY AND MONDAY. THERE
WILL BE CHANCE FOR MAINLY AFTN TSTMS BEGINNING TUESDAY. SOME MORNING
MVFR/IFR WILL BE PSBL DURING THE OUTLOOK PERIOD.
&&
.MARINE...
HIGH RISK OF RIP CURRENTS IN EFFECT FOR TODAY WITH STRONG ONSHORE
FLOW AND HIGH SWELL PERIOD EXPECTED.
MAINTAINED SCA`S THRU THIS AFTN/EVENG FOR THE CHES BAY AND THE
LWR JAMES RIVER NEAR HAMPTON ROADS BRIDGE TUNNEL...AND THRU THIS
AFTN OR THRU LATE TNGT FOR THE CSTL WTRS...DUE TO STRNG NE OR E
WNDS CAUSED BY PRESSURE GRADIENT BETWEEN HI PRES JUST OFF THE NEW
ENGLAND CST AND LO PRES MOVNG NWRD FM JUST OFF THE NC CST. WAVES
OVR THE CHES BAY WILL BLD TO 3-5 FT WITH SEAS OVR THE COASTAL
WTRS BLDNG TO 5-6 FT. AFOREMENTIONED LO PRES WEAKENS AND
DISSIPATES OVR VA SUN MORNG. A LOT OF UNCERTAINTY STILL WITH THE
EVENTUAL TRACK OF TS ISAAC (SEE LATEST NHC FCST FOR DETAILS).
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR ANZ632-
634.
SMALL CRAFT ADVISORY UNTIL 1 AM EDT SUNDAY FOR ANZ630-631.
SMALL CRAFT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR ANZ638-
656-658.
SMALL CRAFT ADVISORY UNTIL 1 PM EDT SUNDAY FOR ANZ650-652-654.
&&
$$
SYNOPSIS...AJZ/ALB/SAM
NEAR TERM...AJZ/ALB
SHORT TERM...AJZ
LONG TERM...MAS
AVIATION...LSA
MARINE...TMG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
317 PM CDT SAT AUG 25 2012
.DISCUSSION...
A DUO OF WEAK SHORTWAVES IS DETECTABLE IN EARLY AFTERNOON RADAR
IMAGERY...ONE ROTATING FROM EAST CENTRAL MN INTO WEST CENTRAL
WISCONSIN...AND THE OTHER OVER NORTHEAST IA. MEANWHILE...THE
PRECIPITATION ASSOCIATED WITH THE NORTHERN STREAM TROUGH OVER
NORTHWEST ONTARIO IS SHIFTING TOWARD LAKE SUPERIOR. THE DYNAMICS
AND 850-700MB MOISTURE TRANSPORT ASSOCIATED WITH THESE FEATURES
WILL CONTINUE SHIFTING EAST OF THE FORECAST AREA DURING THE LATE
AFTERNOON AND EARLY EVENING...WITH ONLY WIDELY SCATTERED SHOWERS
LINGERING OVER WEST CENTRAL WI AFTER DARK. CONCERN THEN SHIFTS TO
CLOUD COVER AND THE POTENTIAL FOR FOG DEVELOPMENT OVERNIGHT.
SURFACE COLD FRONT HAS ENTERED WEST/NORTH CENTRAL MN
TODAY...ALTHOUGH IT WILL WASH OUT PRIOR TO REACHING CENTRAL MN.
WHILE POST-FRONTAL DEWPOINTS ARE IN THE MID TO UPPER 40S...PRE-
FRONTAL DEWPOINTS BETWEEN 65 AND 70 DEGREES ARE COMMON THIS
AFTERNOON ACROSS THE CWFA. THEREFORE...GIVEN THE LIGHT WIND
FIELD...AREAS THAT ARE ABLE TO CLEAR OUT TONIGHT WILL BE
SUSCEPTIBLE TO FOG DEVELOPMENT. THIS APPEARS MOST LIKELY ACROSS
WEST CENTRAL MN. FOR SOUTH CENTRAL MN...SHORT RANGE
MODELS...INCLUDING THE RAP AND THE NAM...INDICATE STRATUS CLOUDS
WILL LIFT OUT OF IOWA OVERNIGHT...SO LOW CEILINGS WILL BE MORE OF
A CONCERN THERE.
ON SUNDAY...A FEW SHOWERS MAY BE LINGERING FROM NEAR EAU CLAIRE TO
LADYSMITH IN THE MORNING. AN OTHERWISE DRY DAY IS EXPECTED...AS THE
AREA REMAINS SANDWICHED BETWEEN THE HUDSON BAY CYCLONE AND THE
AMPLIFYING WESTERN RIDGE. AFTER MORNING FOG AND LINGERING LOW CLOUDS
CLEAR...TEMPERATURES WILL REBOUND INTO THE LOW/MID 80S DURING THE
AFTERNOON UNDER MOSTLY SUNNY SKIES AND LIGHT WEST/SOUTHWEST WINDS.
THE MAIN WEATHER HEADLINE FOR THE UPCOMING WEEK WILL BE VERY WARM
TEMPERATURES...AS THE WESTERN RIDGE EXPANDS INTO THE CENTRAL UNITED
STATE. BY MID WEEK...TEMPERATURES WILL BE AROUND 15 DEGREES ABOVE
NORMAL...WITH HIGHS IN THE UPPER 80S TO LOWER 90S COMMON FROM
TUESDAY THROUGH THURSDAY. STILL CAN/T RULE OUT AN ARBITRARY SHOWER OR
THUNDERSTORM...BUT NO ORGANIZED PRECIPITATION IS ANTICIPATED THROUGH
NEXT WEEK.
THE RIDGE IS EXPECTED TO FLATTEN TOWARD THE END OF THE WORK WEEK
INTO LABOR DAY WEEKEND AS A SHORTWAVE TROUGH TRACKS ACROSS THE
PACIFIC NORTHWEST. THE EVOLUTION OF TC ISAAC WILL COME INTO PLAY
HOWEVER...AND FACTOR INTO HOW MUCH OF A COOL DOWN WE WILL SEE NEXT
WEEKEND. FORECAST CONFIDENCE AFTER FRIDAY IS THEREFORE RATHER LOW.
&&
.AVIATION.../18Z TAF ISSUANCE/
TRICKY FORECAST ALL AROUND AS MOIST SWRLY FLOW WILL...BUT LACK OF
FORCING WILL KEEP BOUTS OF SHOWERS GOING THROUGH MUCH OF THE
EVENING...WITH LOTS OF UNCERTAINTY SURROUNDING FOG/STRATUS
POTENTIAL TONIGHT. COLD FRONT RIGHT NOW NOT MUCH MORE THAN 10
MILES WEST OF AXN...BUT IS QUICKLY LOSING STEAM/DEFINITION THIS
FAR SOUTH. REMNANTS OF MORNING ACTIVITY FROM SW/SC MN NOW WORKING
THROUGH THE CITIES AND WILL BE MOVING INTO WRN WI THIS AFTERNOON.
FOR PRECIP CHANCES THE REST OF THE DAY...WEAK/MOIST SRLY 850 MB
FLOW WILL LIKELY KEEP SPORADIC SHOWERS GOING...BUT EXTENSIVE CLOUD
COVER WILL LIMIT HEATING AND THUNDER POTENTIAL. WILL BASICALLY
STICK WITH VCSH MENTION FOR MOST TAFS INTO THIS EVENING. WILL
LIKELY SEE A SECOND ROUND OF PRECIP COME UP OUT OF IA
TONIGHT...BUT GUIDANCE ALL PRETTY SIMILAR IN KEEPING MOST OF THIS
PRECIP EAST OF EAU. FOR TONIGHT...FOLLOWED THE RAP/NAM AND EXPECT
A BATCH OF LOW CIGS OVER WRN HALF OF IA TO COME UP INTO SRN MN
THEN WRN WI OVERNIGHT...SO HAVE LOW STRATUS MENTION FOR
MSP/RNH/EAU. FOR RWF/STC...IT WILL EITHER BE STRATUS OR FOG. RIGHT
NOW...SIDED WITH STRATUS REMAINING EAST OF THESE LOCATIONS. WITH
NAM BUFKIT SOUNDINGS SCREAMING FOG FOR RWF/STC...HIT THOSE
LOCATIONS HARD FOR FOG OVERNIGHT. AT AXN...DEWPS IN THE 40S ARE
LITERALLY IN THE NEXT COUNTY TO THE WEST. SOME OF THIS DRY AIR
SHOULD WORK IN THROUGH THE DAY...LIMITING THE FOG POTENTIAL THERE
OVERNIGHT...THOUGH IF AXN DOES NOT SEE THIS DRY AIR...THEN THEY
SHOULD FOLLOW STC/RWF INTO THE FOG. FOR WINDS...AXN MAY BRIEFLY GO
NW THIS AFTERNOON...BUT SFC RIDGE BUILDS IN TONIGHT...WHICH WILL
MAKE FOR MAINLY LGT AND VRB WINDS THROUGH THE NIGHT.
KMSP...LOOKING LIKE IT WILL BE DIFFICULT TO GET MUCH MORE PRECIP
AFTER CURRENT BATCH MOVES THROUGH...BUT WITH MOIST LOW LEVEL FLOW
REMAINING THROUGH THE AFTERNOON...WILL LIKELY SEE HIT AND MISS
SHOWERS CONTINUE INTO THE EVENING. GIVEN CLOUDY/COOL TEMPS
TODAY...SHOULD HAVE NO PROBLEM GETTING REDUCED FLIGHT CONDITIONS
OVERNIGHT. AT THE VERY LEAST...WILL LIKELY SEE CIGS BELOW
1700...BUT IFR IS QUITE POSSIBLE AS WELL. SW WINDS WILL DIE OFF
PRETTY QUICK THIS EVENING AND GO LGT AND VRB TONIGHT WITH SFC
RIDGE BUILDING IN. WINDS SUNDAY LOOK TO BE LIGHT AND OUT OF THE WNW.
/OUTLOOK FOR KMSP/
.MONDAY...VFR. WINDS LGT AND VRB.
.TUESDAY...VFR. WINDS S 5-10 KTS.
.WEDNESDAY...VFR. WINDS SW 10-15 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
LS/MPG
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
128 PM CDT SAT AUG 25 2012
.UPDATE...
18Z TAF UPDATE BELOW.
&&
.AVIATION...
PERIODS OF SCATTERED SHOWERS...WITH ISOLATED CELLS TRANSITIONING
TO THUNDERSTORMS...WITH A MORE MODERATE ONSHORE WIND OF BETWEEN
15-20 MPH THROUGH THE AFTERNOON. MOST OF THE TSRA ACTIVITY WILL
BE CONFINED TO THE CENTRAL FORECAST AREA (HOUSTON) SOUTHWARD...WITH
ANY PASSING CLUSTER NOT PERSISTING FOR MORE THAN 15 OR 20 MINUTES.
LOCALLY GUSTY WINDS TO 20 MPH AND REDUCED VISBIES TO AROUND 2 SM
WITHIN THE STRONGEST STORMS. CLEARING OUT SHORTLY AFTER SUNSET
WITH HIGH MOISTURE VALUES LEADING TO 06-12Z PERIODS OF MVFR DECKS
OVER NON-METRO HUBS. LESS OVERALL PRECIPITATION TOMORROW...MORE
WIDELY SCATTERED CELLS THAT WILL KEEP THE MENTION OF TSRA (OR
SHRA) OUT OF SUNDAY`S TAF. 31
&&
.PREV DISCUSSION... /ISSUED 1043 AM CDT SAT AUG 25 2012/
UPDATE...
SEE MORNING UPDATE.
DISCUSSION...
12Z SOUNDINGS SHOWED PW VALUES BETWEEN 1.9 INCHES SOUTHWEST TO
2.30 INCHES OVER THE EXTREME EAST. CONVECTIVE TEMPS ARE BETWEEN 83
DEGREES OVER THE EAST AND AROUND 88 DEGREES SOUTHWEST. 250 MB
WINDS REMAIN DIVERGENT SO FEEL PARAMETERS ARE IN PLACE FOR A
DECENT CHANCE OF SHRA/TSRA TODAY. TEMPS AT 10 AM ARE ALREADY IN
THE MID AND UPPER 80S SO FEEL COVERAGE WILL BEGIN TO FILL IN. THE
LATEST RAP MODEL SHOWS PRECIP EXPANDING INTO THE NORTHWEST ZONES
LATE THIS AFTN AND AM TEMPTED TO BOOST POPS BUT WILL WATCH TRENDS
BEFORE MAKING THAT CALL. REST OF FCST LOOKS ON TRACK. 43
&&
PREV DISCUSSION... /ISSUED 626 AM CDT SAT AUG 25 2012/
AVIATION...
SCATTERED SHOWERS OFFSHORE CONTINUE TO APPROACH THE COAST WHILE
ADDITIONAL SHOWERS ARE FINALLY BEGINNING TO DEVELOP INLAND NEAR
GALVESTON BAY. FURTHER NORTH...AM A BIT CONCERNED THAT VSBYS FOR
CXO WILL DROP SHARPLY OVER THE FIRST HOUR OF THE TAF PERIOD AS
SKIES CLEAR AND WINDS HAVE BECOME CALM. OTHERWISE VFR CONDITIONS
SHOULD PREVAIL THROUGH THE TAF PERIOD WITH ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS THROUGH THE AFTERNOON HOURS TODAY.
COVERAGE SHOULD BE A BIT LESS THAN YESTERDAY AND CONFINED MAINLY
TO THE EASTERN TWO THIRDS OF THE CWA...THUS WILL NOT CARRY A
MENTION OF VCTS FOR CLL THIS AFTERNOON. WINDS OVERNIGHT INTO
SUNDAY SHOULD BE LOWER THAN TONIGHT AS THE PRESSURE GRADIENT
BEGINS TO RELAX ACROSS THE REGION. 38
PREV DISCUSSION... /ISSUED 430 AM CDT SAT AUG 25 2012/
DISCUSSION...
IR SATELLITE LESS CLOUDY AND RADAR LOOPS LESS ACTIVE THIS MORNING
BUT A FEW SHRA ARE NOTED OVER THE WATER AND OVER JACKSON AND
SOUTHWESTERN MATAGORDA COUNTIES AT 09Z. 00Z 250MB MANUAL ANALYSIS
INDICATES HIGH PRESSURE OVER BAJA CA RIDGING TO THE NW OVER
TX...BELOW AT 500MB VERY WEAK TROUGH NOTED FROM KHGX TO KBRO. FROM
SFC-700MB RIDGE AXIS FROM ATLANTIC SUBTROPICAL HIGH IS IN PLACE
WITH SE TX ON THE FRINGE OF THE CIRCULATION. PWAT GRADIENT RUNS
FROM 1.6 IN WESTERN PART OF FA TO NEAR 2 INCHES EAST OF GLS BAY.
GFS FORECASTS ONSHORE FLOW TODAY WITH A GENERAL INCREASE IN PWATS.
HAVE FINE TUNED PCPN CHANCES TODAY FROM PREVIOUS FORECAST WITH
HIGHER CHANCES AGAIN TO THE SOUTHEAST IN GALVESTON AND CHAMBERS
COUNTIES AND OFFSHORE WATERS. NOT EXPECTING AVERAGE RAINFALL
AMOUNTS TO BE AS HIGH AS YESTERDAY WITH GREATEST AMOUNTS IN THE
SOUTHEAST...PERHAPS AVERAGING 0.25 TO 0.50 INCH LOCALLY. GIVEN
KCLL REACHING 95 YESTERDAY MAX TEMPS IN THE NORTHWEST WERE RAISED
SLIGHTLY TODAY.
TOMORROW MEAN SFC-700MB RIDGING MOVES NORTH TAPERING OFF THE
MOISTURE TAP. GFS SPLITS A PIECE OF THE UPPER TROUGH NOW OVER THE
TX PANHANDLE TO OUR WEST TOMORROW SO CANNOT RULE OUT PCPN CHANCES
BUT THEY ARE LOWER THAN TODAY. BY MONDAY ISAAC IS FORECAST BY NHC
TO BE IN THE FAR EASTERN GULF. THIS PUTS SE TX IN A GENERALLY DEEP
OFFSHORE FLOW REGIME. INTERESTING FLIES IN THE OINTMENT FOR
TUESDAY IS A WESTERLY MOVING 250MB LOW THAT BREAKS OFF THE TROUGH
NOW IN THE SOUTHEASTERN US AND SOME RELATIVELY HIGH PWAT AIR ALONG
AND AHEAD OF A FRONTAL ZONE TO OUR NORTH. ECM/GFS MOS POPS ARE
QUITE HIGH ON TUESDAY (40 TO NEAR 50 PERCENT) BUT GIVEN THE USUAL
PATTERN OFF TO THE NORTHWEST OF TROPICAL SYSTEMS IN THE GULF THIS
PCPN CHANCE SEEMS HIGH SO WILL COMPROMISE BY LEAVING OUR 20
PERCENT FORECAST IN PLACE. WILL NEED TO CONTINUE TO MONITOR THIS
AS TUESDAY COULD BE BRIEFLY WETTER. WED THOUGH THE NEXT WEEKEND
LOOK VERY DRY AND TEMPERATURES WILL BE WARMING. GFS ENSEMBLE MEAN
MOS IS HIGHER THAN GFS LONG RANGE MOS (MEX) AND THE EXPERIMENTAL
ECM MOS IS EVEN HIGHER. AS A RESULT MAX TEMPS ON THU-FRI WERE
INCREASED.
CORRECTED FOR GRAMMAR. 04
MARINE...
SURFACE PRESSURE GRADIENT REMAINS RATHER TIGHT ACROSS EASTERN TEXAS
AND LOUISIANA THIS MORNING KEEPING WINDS ACROSS THE COASTAL WATERS
AT AROUND 15KTS...THUS WILL KEEP THE CURRENT ADVISORY FLAGS IN PLACE
THROUGH MIDDAY. WINDS SHOULD BEGIN TO EASE ON SUNDAY BEFORE BECOMING
OFFSHORE BY TUESDAY IN RESPONSE TO ISAAC MOVING INTO THE EASTERN
GULF OF MEXICO. AT THIS TIME IT APPEARS THAT ISAAC WILL REMAIN WELL
TO THE EAST OF OUR AREA WITH MARITIME IMPACTS TO THE UPPER TEXAS
COAST LIMITED TO 3 TO 4 FOOT SEAS ACROSS THE OFFSHORE WATERS AND
SLIGHTLY BELOW NORMAL TIDE LEVELS DUE TO NORTHERLY WINDS OF AROUND
10 TO 15 KTS.
ALTHOUGH ISAAC IS NOT FORECAST TO DIRECTLY AFFECT THE UPPER TEXAS
COASTAL WATERS MARINERS ARE URGED TO CONTINUE MONITORING NHC
FORECASTS AND ADVISORIES REGARDING THE SYSTEM AS IT MOVES INTO THE
GULF OF MEXICO EARLY NEXT WEEK. 38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 75 94 75 95 76 / 20 20 10 20 20
HOUSTON (IAH) 76 93 75 94 75 / 20 30 10 30 20
GALVESTON (GLS) 79 90 80 91 81 / 20 30 10 20 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 7 PM CDT THIS EVENING
FOR THE FOLLOWING ZONES: MATAGORDA BAY...WATERS FROM
FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...
WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20
NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM...
WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.
&&
$$
DISCUSSION...42
AVIATION/MARINE...31